drivers/md/raid5.c

   1 /*
   2  * raid5.c : Multiple Devices driver for Linux
   3  *         Copyright (C) 1996, 1997 Ingo Molnar, Miguel de Icaza, Gadi Oxman
   4  *         Copyright (C) 1999, 2000 Ingo Molnar
   5  *         Copyright (C) 2002, 2003 H. Peter Anvin
   6  *
   7  * RAID-4/5/6 management functions.
   8  * Thanks to Penguin Computing for making the RAID-6 development possible
   9  * by donating a test server!
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2, or (at your option)
  14  * any later version.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * (for example /usr/src/linux/COPYING); if not, write to the Free
  18  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  */
  20
  21 /*
  22  * BITMAP UNPLUGGING:
  23  *
  24  * The sequencing for updating the bitmap reliably is a little
  25  * subtle (and I got it wrong the first time) so it deserves some
  26  * explanation.
  27  *
  28  * We group bitmap updates into batches.  Each batch has a number.
  29  * We may write out several batches at once, but that isn't very important.
  30  * conf->seq_write is the number of the last batch successfully written.
  31  * conf->seq_flush is the number of the last batch that was closed to
  32  *    new additions.
  33  * When we discover that we will need to write to any block in a stripe
  34  * (in add_stripe_bio) we update the in-memory bitmap and record in sh->bm_seq
  35  * the number of the batch it will be in. This is seq_flush+1.
  36  * When we are ready to do a write, if that batch hasn't been written yet,
  37  *   we plug the array and queue the stripe for later.
  38  * When an unplug happens, we increment bm_flush, thus closing the current
  39  *   batch.
  40  * When we notice that bm_flush > bm_write, we write out all pending updates
  41  * to the bitmap, and advance bm_write to where bm_flush was.
  42  * This may occasionally write a bit out twice, but is sure never to
  43  * miss any bits.
  44  */
  45
  46 #include <linux/blkdev.h>
  47 #include <linux/kthread.h>
  48 #include <linux/raid/pq.h>
  49 #include <linux/async_tx.h>
  50 #include <linux/module.h>
  51 #include <linux/async.h>
  52 #include <linux/seq_file.h>
  53 #include <linux/cpu.h>
  54 #include <linux/slab.h>
  55 #include <linux/ratelimit.h>
  56 #include <linux/nodemask.h>
  57 #include <linux/flex_array.h>
  58 #include <linux/sched/signal.h>
  59
  60 #include <trace/events/block.h>
  61 #include <linux/list_sort.h>
  62
  63 #include "md.h"
  64 #include "raid5.h"
  65 #include "raid0.h"
  66 #include "bitmap.h"
  67 #include "raid5-log.h"
  68
  69 #define UNSUPPORTED_MDDEV_FLAGS (1L << MD_FAILFAST_SUPPORTED)
  70
  71 #define cpu_to_group(cpu) cpu_to_node(cpu)
  72 #define ANY_GROUP NUMA_NO_NODE
  73
  74 static bool devices_handle_discard_safely = false;
  75 module_param(devices_handle_discard_safely, bool, 0644);
  76 MODULE_PARM_DESC(devices_handle_discard_safely,
  77                  "Set to Y if all devices in each array reliably return zeroes on reads from discarded regions");
  78 static struct workqueue_struct *raid5_wq;
  79
  80 static inline struct hlist_head *stripe_hash(struct r5conf *conf, sector_t sect)
  81 {
  82         int hash = (sect >> STRIPE_SHIFT) & HASH_MASK;
  83         return &conf->stripe_hashtbl[hash];
  84 }
  85
  86 static inline int stripe_hash_locks_hash(sector_t sect)
  87 {
  88         return (sect >> STRIPE_SHIFT) & STRIPE_HASH_LOCKS_MASK;
  89 }
  90
  91 static inline void lock_device_hash_lock(struct r5conf *conf, int hash)
  92 {
  93         spin_lock_irq(conf->hash_locks + hash);
  94         spin_lock(&conf->device_lock);
  95 }
  96
  97 static inline void unlock_device_hash_lock(struct r5conf *conf, int hash)
  98 {
  99         spin_unlock(&conf->device_lock);
 100         spin_unlock_irq(conf->hash_locks + hash);
 101 }
 102
 103 static inline void lock_all_device_hash_locks_irq(struct r5conf *conf)
 104 {
 105         int i;
 106         local_irq_disable();
 107         spin_lock(conf->hash_locks);
 108         for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
 109                 spin_lock_nest_lock(conf->hash_locks + i, conf->hash_locks);
 110         spin_lock(&conf->device_lock);
 111 }
 112
 113 static inline void unlock_all_device_hash_locks_irq(struct r5conf *conf)
 114 {
 115         int i;
 116         spin_unlock(&conf->device_lock);
 117         for (i = NR_STRIPE_HASH_LOCKS; i; i--)
 118                 spin_unlock(conf->hash_locks + i - 1);
 119         local_irq_enable();
 120 }
 121
 122 /* Find first data disk in a raid6 stripe */
 123 static inline int raid6_d0(struct stripe_head *sh)
 124 {
 125         if (sh->ddf_layout)
 126                 /* ddf always start from first device */
 127                 return 0;
 128         /* md starts just after Q block */
 129         if (sh->qd_idx == sh->disks - 1)
 130                 return 0;
 131         else
 132                 return sh->qd_idx + 1;
 133 }
 134 static inline int raid6_next_disk(int disk, int raid_disks)
 135 {
 136         disk++;
 137         return (disk < raid_disks) ? disk : 0;
 138 }
 139
 140 /* When walking through the disks in a raid5, starting at raid6_d0,
 141  * We need to map each disk to a 'slot', where the data disks are slot
 142  * 0 .. raid_disks-3, the parity disk is raid_disks-2 and the Q disk
 143  * is raid_disks-1.  This help does that mapping.
 144  */
 145 static int raid6_idx_to_slot(int idx, struct stripe_head *sh,
 146                              int *count, int syndrome_disks)
 147 {
 148         int slot = *count;
 149
 150         if (sh->ddf_layout)
 151                 (*count)++;
 152         if (idx == sh->pd_idx)
 153                 return syndrome_disks;
 154         if (idx == sh->qd_idx)
 155                 return syndrome_disks + 1;
 156         if (!sh->ddf_layout)
 157                 (*count)++;
 158         return slot;
 159 }
 160
 161 static void print_raid5_conf (struct r5conf *conf);
 162
 163 static int stripe_operations_active(struct stripe_head *sh)
 164 {
 165         return sh->check_state || sh->reconstruct_state ||
 166                test_bit(STRIPE_BIOFILL_RUN, &sh->state) ||
 167                test_bit(STRIPE_COMPUTE_RUN, &sh->state);
 168 }
 169
 170 static bool stripe_is_lowprio(struct stripe_head *sh)
 171 {
 172         return (test_bit(STRIPE_R5C_FULL_STRIPE, &sh->state) ||
 173                 test_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state)) &&
 174                !test_bit(STRIPE_R5C_CACHING, &sh->state);
 175 }
 176
 177 static void raid5_wakeup_stripe_thread(struct stripe_head *sh)
 178 {
 179         struct r5conf *conf = sh->raid_conf;
 180         struct r5worker_group *group;
 181         int thread_cnt;
 182         int i, cpu = sh->cpu;
 183
 184         if (!cpu_online(cpu)) {
 185                 cpu = cpumask_any(cpu_online_mask);
 186                 sh->cpu = cpu;
 187         }
 188
 189         if (list_empty(&sh->lru)) {
 190                 struct r5worker_group *group;
 191                 group = conf->worker_groups + cpu_to_group(cpu);
 192                 if (stripe_is_lowprio(sh))
 193                         list_add_tail(&sh->lru, &group->loprio_list);
 194                 else
 195                         list_add_tail(&sh->lru, &group->handle_list);
 196                 group->stripes_cnt++;
 197                 sh->group = group;
 198         }
 199
 200         if (conf->worker_cnt_per_group == 0) {
 201                 md_wakeup_thread(conf->mddev->thread);
 202                 return;
 203         }
 204
 205         group = conf->worker_groups + cpu_to_group(sh->cpu);
 206
 207         group->workers[0].working = true;
 208         /* at least one worker should run to avoid race */
 209         queue_work_on(sh->cpu, raid5_wq, &group->workers[0].work);
 210
 211         thread_cnt = group->stripes_cnt / MAX_STRIPE_BATCH - 1;
 212         /* wakeup more workers */
 213         for (i = 1; i < conf->worker_cnt_per_group && thread_cnt > 0; i++) {
 214                 if (group->workers[i].working == false) {
 215                         group->workers[i].working = true;
 216                         queue_work_on(sh->cpu, raid5_wq,
 217                                       &group->workers[i].work);
 218                         thread_cnt--;
 219                 }
 220         }
 221 }
 222
 223 static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh,
 224                               struct list_head *temp_inactive_list)
 225 {
 226         int i;
 227         int injournal = 0;      /* number of date pages with R5_InJournal */
 228
 229         BUG_ON(!list_empty(&sh->lru));
 230         BUG_ON(atomic_read(&conf->active_stripes)==0);
 231
 232         if (r5c_is_writeback(conf->log))
 233                 for (i = sh->disks; i--; )
 234                         if (test_bit(R5_InJournal, &sh->dev[i].flags))
 235                                 injournal++;
 236         /*
 237          * When quiesce in r5c write back, set STRIPE_HANDLE for stripes with
 238          * data in journal, so they are not released to cached lists
 239          */
 240         if (conf->quiesce && r5c_is_writeback(conf->log) &&
 241             !test_bit(STRIPE_HANDLE, &sh->state) && injournal != 0) {
 242                 if (test_bit(STRIPE_R5C_CACHING, &sh->state))
 243                         r5c_make_stripe_write_out(sh);
 244                 set_bit(STRIPE_HANDLE, &sh->state);
 245         }
 246
 247         if (test_bit(STRIPE_HANDLE, &sh->state)) {
 248                 if (test_bit(STRIPE_DELAYED, &sh->state) &&
 249                     !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 250                         list_add_tail(&sh->lru, &conf->delayed_list);
 251                 else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
 252                            sh->bm_seq - conf->seq_write > 0)
 253                         list_add_tail(&sh->lru, &conf->bitmap_list);
 254                 else {
 255                         clear_bit(STRIPE_DELAYED, &sh->state);
 256                         clear_bit(STRIPE_BIT_DELAY, &sh->state);
 257                         if (conf->worker_cnt_per_group == 0) {
 258                                 if (stripe_is_lowprio(sh))
 259                                         list_add_tail(&sh->lru,
 260                                                         &conf->loprio_list);
 261                                 else
 262                                         list_add_tail(&sh->lru,
 263                                                         &conf->handle_list);
 264                         } else {
 265                                 raid5_wakeup_stripe_thread(sh);
 266                                 return;
 267                         }
 268                 }
 269                 md_wakeup_thread(conf->mddev->thread);
 270         } else {
 271                 BUG_ON(stripe_operations_active(sh));
 272                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 273                         if (atomic_dec_return(&conf->preread_active_stripes)
 274                             < IO_THRESHOLD)
 275                                 md_wakeup_thread(conf->mddev->thread);
 276                 atomic_dec(&conf->active_stripes);
 277                 if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
 278                         if (!r5c_is_writeback(conf->log))
 279                                 list_add_tail(&sh->lru, temp_inactive_list);
 280                         else {
 281                                 WARN_ON(test_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags));
 282                                 if (injournal == 0)
 283                                         list_add_tail(&sh->lru, temp_inactive_list);
 284                                 else if (injournal == conf->raid_disks - conf->max_degraded) {
 285                                         /* full stripe */
 286                                         if (!test_and_set_bit(STRIPE_R5C_FULL_STRIPE, &sh->state))
 287                                                 atomic_inc(&conf->r5c_cached_full_stripes);
 288                                         if (test_and_clear_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state))
 289                                                 atomic_dec(&conf->r5c_cached_partial_stripes);
 290                                         list_add_tail(&sh->lru, &conf->r5c_full_stripe_list);
 291                                         r5c_check_cached_full_stripe(conf);
 292                                 } else
 293                                         /*
 294                                          * STRIPE_R5C_PARTIAL_STRIPE is set in
 295                                          * r5c_try_caching_write(). No need to
 296                                          * set it again.
 297                                          */
 298                                         list_add_tail(&sh->lru, &conf->r5c_partial_stripe_list);
 299                         }
 300                 }
 301         }
 302 }
 303
 304 static void __release_stripe(struct r5conf *conf, struct stripe_head *sh,
 305                              struct list_head *temp_inactive_list)
 306 {
 307         if (atomic_dec_and_test(&sh->count))
 308                 do_release_stripe(conf, sh, temp_inactive_list);
 309 }
 310
 311 /*
 312  * @hash could be NR_STRIPE_HASH_LOCKS, then we have a list of inactive_list
 313  *
 314  * Be careful: Only one task can add/delete stripes from temp_inactive_list at
 315  * given time. Adding stripes only takes device lock, while deleting stripes
 316  * only takes hash lock.
 317  */
 318 static void release_inactive_stripe_list(struct r5conf *conf,
 319                                          struct list_head *temp_inactive_list,
 320                                          int hash)
 321 {
 322         int size;
 323         bool do_wakeup = false;
 324         unsigned long flags;
 325
 326         if (hash == NR_STRIPE_HASH_LOCKS) {
 327                 size = NR_STRIPE_HASH_LOCKS;
 328                 hash = NR_STRIPE_HASH_LOCKS - 1;
 329         } else
 330                 size = 1;
 331         while (size) {
 332                 struct list_head *list = &temp_inactive_list[size - 1];
 333
 334                 /*
 335                  * We don't hold any lock here yet, raid5_get_active_stripe() might
 336                  * remove stripes from the list
 337                  */
 338                 if (!list_empty_careful(list)) {
 339                         spin_lock_irqsave(conf->hash_locks + hash, flags);
 340                         if (list_empty(conf->inactive_list + hash) &&
 341                             !list_empty(list))
 342                                 atomic_dec(&conf->empty_inactive_list_nr);
 343                         list_splice_tail_init(list, conf->inactive_list + hash);
 344                         do_wakeup = true;
 345                         spin_unlock_irqrestore(conf->hash_locks + hash, flags);
 346                 }
 347                 size--;
 348                 hash--;
 349         }
 350
 351         if (do_wakeup) {
 352                 wake_up(&conf->wait_for_stripe);
 353                 if (atomic_read(&conf->active_stripes) == 0)
 354                         wake_up(&conf->wait_for_quiescent);
 355                 if (conf->retry_read_aligned)
 356                         md_wakeup_thread(conf->mddev->thread);
 357         }
 358 }
 359
 360 /* should hold conf->device_lock already */
 361 static int release_stripe_list(struct r5conf *conf,
 362                                struct list_head *temp_inactive_list)
 363 {
 364         struct stripe_head *sh, *t;
 365         int count = 0;
 366         struct llist_node *head;
 367
 368         head = llist_del_all(&conf->released_stripes);
 369         head = llist_reverse_order(head);
 370         llist_for_each_entry_safe(sh, t, head, release_list) {
 371                 int hash;
 372
 373                 /* sh could be readded after STRIPE_ON_RELEASE_LIST is cleard */
 374                 smp_mb();
 375                 clear_bit(STRIPE_ON_RELEASE_LIST, &sh->state);
 376                 /*
 377                  * Don't worry the bit is set here, because if the bit is set
 378                  * again, the count is always > 1. This is true for
 379                  * STRIPE_ON_UNPLUG_LIST bit too.
 380                  */
 381                 hash = sh->hash_lock_index;
 382                 __release_stripe(conf, sh, &temp_inactive_list[hash]);
 383                 count++;
 384         }
 385
 386         return count;
 387 }
 388
 389 void raid5_release_stripe(struct stripe_head *sh)
 390 {
 391         struct r5conf *conf = sh->raid_conf;
 392         unsigned long flags;
 393         struct list_head list;
 394         int hash;
 395         bool wakeup;
 396
 397         /* Avoid release_list until the last reference.
 398          */
 399         if (atomic_add_unless(&sh->count, -1, 1))
 400                 return;
 401
 402         if (unlikely(!conf->mddev->thread) ||
 403                 test_and_set_bit(STRIPE_ON_RELEASE_LIST, &sh->state))
 404                 goto slow_path;
 405         wakeup = llist_add(&sh->release_list, &conf->released_stripes);
 406         if (wakeup)
 407                 md_wakeup_thread(conf->mddev->thread);
 408         return;
 409 slow_path:
 410         local_irq_save(flags);
 411         /* we are ok here if STRIPE_ON_RELEASE_LIST is set or not */
 412         if (atomic_dec_and_lock(&sh->count, &conf->device_lock)) {
 413                 INIT_LIST_HEAD(&list);
 414                 hash = sh->hash_lock_index;
 415                 do_release_stripe(conf, sh, &list);
 416                 spin_unlock(&conf->device_lock);
 417                 release_inactive_stripe_list(conf, &list, hash);
 418         }
 419         local_irq_restore(flags);
 420 }
 421
 422 static inline void remove_hash(struct stripe_head *sh)
 423 {
 424         pr_debug("remove_hash(), stripe %llu\n",
 425                 (unsigned long long)sh->sector);
 426
 427         hlist_del_init(&sh->hash);
 428 }
 429
 430 static inline void insert_hash(struct r5conf *conf, struct stripe_head *sh)
 431 {
 432         struct hlist_head *hp = stripe_hash(conf, sh->sector);
 433
 434         pr_debug("insert_hash(), stripe %llu\n",
 435                 (unsigned long long)sh->sector);
 436
 437         hlist_add_head(&sh->hash, hp);
 438 }
 439
 440 /* find an idle stripe, make sure it is unhashed, and return it. */
 441 static struct stripe_head *get_free_stripe(struct r5conf *conf, int hash)
 442 {
 443         struct stripe_head *sh = NULL;
 444         struct list_head *first;
 445
 446         if (list_empty(conf->inactive_list + hash))
 447                 goto out;
 448         first = (conf->inactive_list + hash)->next;
 449         sh = list_entry(first, struct stripe_head, lru);
 450         list_del_init(first);
 451         remove_hash(sh);
 452         atomic_inc(&conf->active_stripes);
 453         BUG_ON(hash != sh->hash_lock_index);
 454         if (list_empty(conf->inactive_list + hash))
 455                 atomic_inc(&conf->empty_inactive_list_nr);
 456 out:
 457         return sh;
 458 }
 459
 460 static void shrink_buffers(struct stripe_head *sh)
 461 {
 462         struct page *p;
 463         int i;
 464         int num = sh->raid_conf->pool_size;
 465
 466         for (i = 0; i < num ; i++) {
 467                 WARN_ON(sh->dev[i].page != sh->dev[i].orig_page);
 468                 p = sh->dev[i].page;
 469                 if (!p)
 470                         continue;
 471                 sh->dev[i].page = NULL;
 472                 put_page(p);
 473         }
 474
 475         if (sh->ppl_page) {
 476                 put_page(sh->ppl_page);
 477                 sh->ppl_page = NULL;
 478         }
 479 }
 480
 481 static int grow_buffers(struct stripe_head *sh, gfp_t gfp)
 482 {
 483         int i;
 484         int num = sh->raid_conf->pool_size;
 485
 486         for (i = 0; i < num; i++) {
 487                 struct page *page;
 488
 489                 if (!(page = alloc_page(gfp))) {
 490                         return 1;
 491                 }
 492                 sh->dev[i].page = page;
 493                 sh->dev[i].orig_page = page;
 494         }
 495
 496         if (raid5_has_ppl(sh->raid_conf)) {
 497                 sh->ppl_page = alloc_page(gfp);
 498                 if (!sh->ppl_page)
 499                         return 1;
 500         }
 501
 502         return 0;
 503 }
 504
 505 static void raid5_build_block(struct stripe_head *sh, int i, int previous);
 506 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
 507                             struct stripe_head *sh);
 508
 509 static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
 510 {
 511         struct r5conf *conf = sh->raid_conf;
 512         int i, seq;
 513
 514         BUG_ON(atomic_read(&sh->count) != 0);
 515         BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
 516         BUG_ON(stripe_operations_active(sh));
 517         BUG_ON(sh->batch_head);
 518
 519         pr_debug("init_stripe called, stripe %llu\n",
 520                 (unsigned long long)sector);
 521 retry:
 522         seq = read_seqcount_begin(&conf->gen_lock);
 523         sh->generation = conf->generation - previous;
 524         sh->disks = previous ? conf->previous_raid_disks : conf->raid_disks;
 525         sh->sector = sector;
 526         stripe_set_idx(sector, conf, previous, sh);
 527         sh->state = 0;
 528
 529         for (i = sh->disks; i--; ) {
 530                 struct r5dev *dev = &sh->dev[i];
 531
 532                 if (dev->toread || dev->read || dev->towrite || dev->written ||
 533                     test_bit(R5_LOCKED, &dev->flags)) {
 534                         pr_err("sector=%llx i=%d %p %p %p %p %d\n",
 535                                (unsigned long long)sh->sector, i, dev->toread,
 536                                dev->read, dev->towrite, dev->written,
 537                                test_bit(R5_LOCKED, &dev->flags));
 538                         WARN_ON(1);
 539                 }
 540                 dev->flags = 0;
 541                 raid5_build_block(sh, i, previous);
 542         }
 543         if (read_seqcount_retry(&conf->gen_lock, seq))
 544                 goto retry;
 545         sh->overwrite_disks = 0;
 546         insert_hash(conf, sh);
 547         sh->cpu = smp_processor_id();
 548         set_bit(STRIPE_BATCH_READY, &sh->state);
 549 }
 550
 551 static struct stripe_head *__find_stripe(struct r5conf *conf, sector_t sector,
 552                                          short generation)
 553 {
 554         struct stripe_head *sh;
 555
 556         pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
 557         hlist_for_each_entry(sh, stripe_hash(conf, sector), hash)
 558                 if (sh->sector == sector && sh->generation == generation)
 559                         return sh;
 560         pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
 561         return NULL;
 562 }
 563
 564 /*
 565  * Need to check if array has failed when deciding whether to:
 566  *  - start an array
 567  *  - remove non-faulty devices
 568  *  - add a spare
 569  *  - allow a reshape
 570  * This determination is simple when no reshape is happening.
 571  * However if there is a reshape, we need to carefully check
 572  * both the before and after sections.
 573  * This is because some failed devices may only affect one
 574  * of the two sections, and some non-in_sync devices may
 575  * be insync in the section most affected by failed devices.
 576  */
 577 int raid5_calc_degraded(struct r5conf *conf)
 578 {
 579         int degraded, degraded2;
 580         int i;
 581
 582         rcu_read_lock();
 583         degraded = 0;
 584         for (i = 0; i < conf->previous_raid_disks; i++) {
 585                 struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
 586                 if (rdev && test_bit(Faulty, &rdev->flags))
 587                         rdev = rcu_dereference(conf->disks[i].replacement);
 588                 if (!rdev || test_bit(Faulty, &rdev->flags))
 589                         degraded++;
 590                 else if (test_bit(In_sync, &rdev->flags))
 591                         ;
 592                 else
 593                         /* not in-sync or faulty.
 594                          * If the reshape increases the number of devices,
 595                          * this is being recovered by the reshape, so
 596                          * this 'previous' section is not in_sync.
 597                          * If the number of devices is being reduced however,
 598                          * the device can only be part of the array if
 599                          * we are reverting a reshape, so this section will
 600                          * be in-sync.
 601                          */
 602                         if (conf->raid_disks >= conf->previous_raid_disks)
 603                                 degraded++;
 604         }
 605         rcu_read_unlock();
 606         if (conf->raid_disks == conf->previous_raid_disks)
 607                 return degraded;
 608         rcu_read_lock();
 609         degraded2 = 0;
 610         for (i = 0; i < conf->raid_disks; i++) {
 611                 struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
 612                 if (rdev && test_bit(Faulty, &rdev->flags))
 613                         rdev = rcu_dereference(conf->disks[i].replacement);
 614                 if (!rdev || test_bit(Faulty, &rdev->flags))
 615                         degraded2++;
 616                 else if (test_bit(In_sync, &rdev->flags))
 617                         ;
 618                 else
 619                         /* not in-sync or faulty.
 620                          * If reshape increases the number of devices, this
 621                          * section has already been recovered, else it
 622                          * almost certainly hasn't.
 623                          */
 624                         if (conf->raid_disks <= conf->previous_raid_disks)
 625                                 degraded2++;
 626         }
 627         rcu_read_unlock();
 628         if (degraded2 > degraded)
 629                 return degraded2;
 630         return degraded;
 631 }
 632
 633 static int has_failed(struct r5conf *conf)
 634 {
 635         int degraded;
 636
 637         if (conf->mddev->reshape_position == MaxSector)
 638                 return conf->mddev->degraded > conf->max_degraded;
 639
 640         degraded = raid5_calc_degraded(conf);
 641         if (degraded > conf->max_degraded)
 642                 return 1;
 643         return 0;
 644 }
 645
 646 struct stripe_head *
 647 raid5_get_active_stripe(struct r5conf *conf, sector_t sector,
 648                         int previous, int noblock, int noquiesce)
 649 {
 650         struct stripe_head *sh;
 651         int hash = stripe_hash_locks_hash(sector);
 652         int inc_empty_inactive_list_flag;
 653
 654         pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
 655
 656         spin_lock_irq(conf->hash_locks + hash);
 657
 658         do {
 659                 wait_event_lock_irq(conf->wait_for_quiescent,
 660                                     conf->quiesce == 0 || noquiesce,
 661                                     *(conf->hash_locks + hash));
 662                 sh = __find_stripe(conf, sector, conf->generation - previous);
 663                 if (!sh) {
 664                         if (!test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state)) {
 665                                 sh = get_free_stripe(conf, hash);
 666                                 if (!sh && !test_bit(R5_DID_ALLOC,
 667                                                      &conf->cache_state))
 668                                         set_bit(R5_ALLOC_MORE,
 669                                                 &conf->cache_state);
 670                         }
 671                         if (noblock && sh == NULL)
 672                                 break;
 673
 674                         r5c_check_stripe_cache_usage(conf);
 675                         if (!sh) {
 676                                 set_bit(R5_INACTIVE_BLOCKED,
 677                                         &conf->cache_state);
 678                                 r5l_wake_reclaim(conf->log, 0);
 679                                 wait_event_lock_irq(
 680                                         conf->wait_for_stripe,
 681                                         !list_empty(conf->inactive_list + hash) &&
 682                                         (atomic_read(&conf->active_stripes)
 683                                          < (conf->max_nr_stripes * 3 / 4)
 684                                          || !test_bit(R5_INACTIVE_BLOCKED,
 685                                                       &conf->cache_state)),
 686                                         *(conf->hash_locks + hash));
 687                                 clear_bit(R5_INACTIVE_BLOCKED,
 688                                           &conf->cache_state);
 689                         } else {
 690                                 init_stripe(sh, sector, previous);
 691                                 atomic_inc(&sh->count);
 692                         }
 693                 } else if (!atomic_inc_not_zero(&sh->count)) {
 694                         spin_lock(&conf->device_lock);
 695                         if (!atomic_read(&sh->count)) {
 696                                 if (!test_bit(STRIPE_HANDLE, &sh->state))
 697                                         atomic_inc(&conf->active_stripes);
 698                                 BUG_ON(list_empty(&sh->lru) &&
 699                                        !test_bit(STRIPE_EXPANDING, &sh->state));
 700                                 inc_empty_inactive_list_flag = 0;
 701                                 if (!list_empty(conf->inactive_list + hash))
 702                                         inc_empty_inactive_list_flag = 1;
 703                                 list_del_init(&sh->lru);
 704                                 if (list_empty(conf->inactive_list + hash) && inc_empty_inactive_list_flag)
 705                                         atomic_inc(&conf->empty_inactive_list_nr);
 706                                 if (sh->group) {
 707                                         sh->group->stripes_cnt--;
 708                                         sh->group = NULL;
 709                                 }
 710                         }
 711                         atomic_inc(&sh->count);
 712                         spin_unlock(&conf->device_lock);
 713                 }
 714         } while (sh == NULL);
 715
 716         spin_unlock_irq(conf->hash_locks + hash);
 717         return sh;
 718 }
 719
 720 static bool is_full_stripe_write(struct stripe_head *sh)
 721 {
 722         BUG_ON(sh->overwrite_disks > (sh->disks - sh->raid_conf->max_degraded));
 723         return sh->overwrite_disks == (sh->disks - sh->raid_conf->max_degraded);
 724 }
 725
 726 static void lock_two_stripes(struct stripe_head *sh1, struct stripe_head *sh2)
 727 {
 728         local_irq_disable();
 729         if (sh1 > sh2) {
 730                 spin_lock(&sh2->stripe_lock);
 731                 spin_lock_nested(&sh1->stripe_lock, 1);
 732         } else {
 733                 spin_lock(&sh1->stripe_lock);
 734                 spin_lock_nested(&sh2->stripe_lock, 1);
 735         }
 736 }
 737
 738 static void unlock_two_stripes(struct stripe_head *sh1, struct stripe_head *sh2)
 739 {
 740         spin_unlock(&sh1->stripe_lock);
 741         spin_unlock(&sh2->stripe_lock);
 742         local_irq_enable();
 743 }
 744
 745 /* Only freshly new full stripe normal write stripe can be added to a batch list */
 746 static bool stripe_can_batch(struct stripe_head *sh)
 747 {
 748         struct r5conf *conf = sh->raid_conf;
 749
 750         if (conf->log || raid5_has_ppl(conf))
 751                 return false;
 752         return test_bit(STRIPE_BATCH_READY, &sh->state) &&
 753                 !test_bit(STRIPE_BITMAP_PENDING, &sh->state) &&
 754                 is_full_stripe_write(sh);
 755 }
 756
 757 /* we only do back search */
 758 static void stripe_add_to_batch_list(struct r5conf *conf, struct stripe_head *sh)
 759 {
 760         struct stripe_head *head;
 761         sector_t head_sector, tmp_sec;
 762         int hash;
 763         int dd_idx;
 764         int inc_empty_inactive_list_flag;
 765
 766         /* Don't cross chunks, so stripe pd_idx/qd_idx is the same */
 767         tmp_sec = sh->sector;
 768         if (!sector_div(tmp_sec, conf->chunk_sectors))
 769                 return;
 770         head_sector = sh->sector - STRIPE_SECTORS;
 771
 772         hash = stripe_hash_locks_hash(head_sector);
 773         spin_lock_irq(conf->hash_locks + hash);
 774         head = __find_stripe(conf, head_sector, conf->generation);
 775         if (head && !atomic_inc_not_zero(&head->count)) {
 776                 spin_lock(&conf->device_lock);
 777                 if (!atomic_read(&head->count)) {
 778                         if (!test_bit(STRIPE_HANDLE, &head->state))
 779                                 atomic_inc(&conf->active_stripes);
 780                         BUG_ON(list_empty(&head->lru) &&
 781                                !test_bit(STRIPE_EXPANDING, &head->state));
 782                         inc_empty_inactive_list_flag = 0;
 783                         if (!list_empty(conf->inactive_list + hash))
 784                                 inc_empty_inactive_list_flag = 1;
 785                         list_del_init(&head->lru);
 786                         if (list_empty(conf->inactive_list + hash) && inc_empty_inactive_list_flag)
 787                                 atomic_inc(&conf->empty_inactive_list_nr);
 788                         if (head->group) {
 789                                 head->group->stripes_cnt--;
 790                                 head->group = NULL;
 791                         }
 792                 }
 793                 atomic_inc(&head->count);
 794                 spin_unlock(&conf->device_lock);
 795         }
 796         spin_unlock_irq(conf->hash_locks + hash);
 797
 798         if (!head)
 799                 return;
 800         if (!stripe_can_batch(head))
 801                 goto out;
 802
 803         lock_two_stripes(head, sh);
 804         /* clear_batch_ready clear the flag */
 805         if (!stripe_can_batch(head) || !stripe_can_batch(sh))
 806                 goto unlock_out;
 807
 808         if (sh->batch_head)
 809                 goto unlock_out;
 810
 811         dd_idx = 0;
 812         while (dd_idx == sh->pd_idx || dd_idx == sh->qd_idx)
 813                 dd_idx++;
 814         if (head->dev[dd_idx].towrite->bi_opf != sh->dev[dd_idx].towrite->bi_opf ||
 815             bio_op(head->dev[dd_idx].towrite) != bio_op(sh->dev[dd_idx].towrite))
 816                 goto unlock_out;
 817
 818         if (head->batch_head) {
 819                 spin_lock(&head->batch_head->batch_lock);
 820                 /* This batch list is already running */
 821                 if (!stripe_can_batch(head)) {
 822                         spin_unlock(&head->batch_head->batch_lock);
 823                         goto unlock_out;
 824                 }
 825
 826                 /*
 827                  * at this point, head's BATCH_READY could be cleared, but we
 828                  * can still add the stripe to batch list
 829                  */
 830                 list_add(&sh->batch_list, &head->batch_list);
 831                 spin_unlock(&head->batch_head->batch_lock);
 832
 833                 sh->batch_head = head->batch_head;
 834         } else {
 835                 head->batch_head = head;
 836                 sh->batch_head = head->batch_head;
 837                 spin_lock(&head->batch_lock);
 838                 list_add_tail(&sh->batch_list, &head->batch_list);
 839                 spin_unlock(&head->batch_lock);
 840         }
 841
 842         if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 843                 if (atomic_dec_return(&conf->preread_active_stripes)
 844                     < IO_THRESHOLD)
 845                         md_wakeup_thread(conf->mddev->thread);
 846
 847         if (test_and_clear_bit(STRIPE_BIT_DELAY, &sh->state)) {
 848                 int seq = sh->bm_seq;
 849                 if (test_bit(STRIPE_BIT_DELAY, &sh->batch_head->state) &&
 850                     sh->batch_head->bm_seq > seq)
 851                         seq = sh->batch_head->bm_seq;
 852                 set_bit(STRIPE_BIT_DELAY, &sh->batch_head->state);
 853                 sh->batch_head->bm_seq = seq;
 854         }
 855
 856         atomic_inc(&sh->count);
 857 unlock_out:
 858         unlock_two_stripes(head, sh);
 859 out:
 860         raid5_release_stripe(head);
 861 }
 862
 863 /* Determine if 'data_offset' or 'new_data_offset' should be used
 864  * in this stripe_head.
 865  */
 866 static int use_new_offset(struct r5conf *conf, struct stripe_head *sh)
 867 {
 868         sector_t progress = conf->reshape_progress;
 869         /* Need a memory barrier to make sure we see the value
 870          * of conf->generation, or ->data_offset that was set before
 871          * reshape_progress was updated.
 872          */
 873         smp_rmb();
 874         if (progress == MaxSector)
 875                 return 0;
 876         if (sh->generation == conf->generation - 1)
 877                 return 0;
 878         /* We are in a reshape, and this is a new-generation stripe,
 879          * so use new_data_offset.
 880          */
 881         return 1;
 882 }
 883
 884 static void dispatch_bio_list(struct bio_list *tmp)
 885 {
 886         struct bio *bio;
 887
 888         while ((bio = bio_list_pop(tmp)))
 889                 generic_make_request(bio);
 890 }
 891
 892 static int cmp_stripe(void *priv, struct list_head *a, struct list_head *b)
 893 {
 894         const struct r5pending_data *da = list_entry(a,
 895                                 struct r5pending_data, sibling);
 896         const struct r5pending_data *db = list_entry(b,
 897                                 struct r5pending_data, sibling);
 898         if (da->sector > db->sector)
 899                 return 1;
 900         if (da->sector < db->sector)
 901                 return -1;
 902         return 0;
 903 }
 904
 905 static void dispatch_defer_bios(struct r5conf *conf, int target,
 906                                 struct bio_list *list)
 907 {
 908         struct r5pending_data *data;
 909         struct list_head *first, *next = NULL;
 910         int cnt = 0;
 911
 912         if (conf->pending_data_cnt == 0)
 913                 return;
 914
 915         list_sort(NULL, &conf->pending_list, cmp_stripe);
 916
 917         first = conf->pending_list.next;
 918
 919         /* temporarily move the head */
 920         if (conf->next_pending_data)
 921                 list_move_tail(&conf->pending_list,
 922                                 &conf->next_pending_data->sibling);
 923
 924         while (!list_empty(&conf->pending_list)) {
 925                 data = list_first_entry(&conf->pending_list,
 926                         struct r5pending_data, sibling);
 927                 if (&data->sibling == first)
 928                         first = data->sibling.next;
 929                 next = data->sibling.next;
 930
 931                 bio_list_merge(list, &data->bios);
 932                 list_move(&data->sibling, &conf->free_list);
 933                 cnt++;
 934                 if (cnt >= target)
 935                         break;
 936         }
 937         conf->pending_data_cnt -= cnt;
 938         BUG_ON(conf->pending_data_cnt < 0 || cnt < target);
 939
 940         if (next != &conf->pending_list)
 941                 conf->next_pending_data = list_entry(next,
 942                                 struct r5pending_data, sibling);
 943         else
 944                 conf->next_pending_data = NULL;
 945         /* list isn't empty */
 946         if (first != &conf->pending_list)
 947                 list_move_tail(&conf->pending_list, first);
 948 }
 949
 950 static void flush_deferred_bios(struct r5conf *conf)
 951 {
 952         struct bio_list tmp = BIO_EMPTY_LIST;
 953
 954         if (conf->pending_data_cnt == 0)
 955                 return;
 956
 957         spin_lock(&conf->pending_bios_lock);
 958         dispatch_defer_bios(conf, conf->pending_data_cnt, &tmp);
 959         BUG_ON(conf->pending_data_cnt != 0);
 960         spin_unlock(&conf->pending_bios_lock);
 961
 962         dispatch_bio_list(&tmp);
 963 }
 964
 965 static void defer_issue_bios(struct r5conf *conf, sector_t sector,
 966                                 struct bio_list *bios)
 967 {
 968         struct bio_list tmp = BIO_EMPTY_LIST;
 969         struct r5pending_data *ent;
 970
 971         spin_lock(&conf->pending_bios_lock);
 972         ent = list_first_entry(&conf->free_list, struct r5pending_data,
 973                                                         sibling);
 974         list_move_tail(&ent->sibling, &conf->pending_list);
 975         ent->sector = sector;
 976         bio_list_init(&ent->bios);
 977         bio_list_merge(&ent->bios, bios);
 978         conf->pending_data_cnt++;
 979         if (conf->pending_data_cnt >= PENDING_IO_MAX)
 980                 dispatch_defer_bios(conf, PENDING_IO_ONE_FLUSH, &tmp);
 981
 982         spin_unlock(&conf->pending_bios_lock);
 983
 984         dispatch_bio_list(&tmp);
 985 }
 986
 987 static void
 988 raid5_end_read_request(struct bio *bi);
 989 static void
 990 raid5_end_write_request(struct bio *bi);
 991
 992 static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
 993 {
 994         struct r5conf *conf = sh->raid_conf;
 995         int i, disks = sh->disks;
 996         struct stripe_head *head_sh = sh;
 997         struct bio_list pending_bios = BIO_EMPTY_LIST;
 998         bool should_defer;
 999
1000         might_sleep();
1001
1002         if (log_stripe(sh, s) == 0)
1003                 return;
1004
1005         should_defer = conf->batch_bio_dispatch && conf->group_cnt;
1006
1007         for (i = disks; i--; ) {
1008                 int op, op_flags = 0;
1009                 int replace_only = 0;
1010                 struct bio *bi, *rbi;
1011                 struct md_rdev *rdev, *rrdev = NULL;
1012
1013                 sh = head_sh;
1014                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
1015                         op = REQ_OP_WRITE;
1016                         if (test_and_clear_bit(R5_WantFUA, &sh->dev[i].flags))
1017                                 op_flags = REQ_FUA;
1018                         if (test_bit(R5_Discard, &sh->dev[i].flags))
1019                                 op = REQ_OP_DISCARD;
1020                 } else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
1021                         op = REQ_OP_READ;
1022                 else if (test_and_clear_bit(R5_WantReplace,
1023                                             &sh->dev[i].flags)) {
1024                         op = REQ_OP_WRITE;
1025                         replace_only = 1;
1026                 } else
1027                         continue;
1028                 if (test_and_clear_bit(R5_SyncIO, &sh->dev[i].flags))
1029                         op_flags |= REQ_SYNC;
1030
1031 again:
1032                 bi = &sh->dev[i].req;
1033                 rbi = &sh->dev[i].rreq; /* For writing to replacement */
1034
1035                 rcu_read_lock();
1036                 rrdev = rcu_dereference(conf->disks[i].replacement);
1037                 smp_mb(); /* Ensure that if rrdev is NULL, rdev won't be */
1038                 rdev = rcu_dereference(conf->disks[i].rdev);
1039                 if (!rdev) {
1040                         rdev = rrdev;
1041                         rrdev = NULL;
1042                 }
1043                 if (op_is_write(op)) {
1044                         if (replace_only)
1045                                 rdev = NULL;
1046                         if (rdev == rrdev)
1047                                 /* We raced and saw duplicates */
1048                                 rrdev = NULL;
1049                 } else {
1050                         if (test_bit(R5_ReadRepl, &head_sh->dev[i].flags) && rrdev)
1051                                 rdev = rrdev;
1052                         rrdev = NULL;
1053                 }
1054
1055                 if (rdev && test_bit(Faulty, &rdev->flags))
1056                         rdev = NULL;
1057                 if (rdev)
1058                         atomic_inc(&rdev->nr_pending);
1059                 if (rrdev && test_bit(Faulty, &rrdev->flags))
1060                         rrdev = NULL;
1061                 if (rrdev)
1062                         atomic_inc(&rrdev->nr_pending);
1063                 rcu_read_unlock();
1064
1065                 /* We have already checked bad blocks for reads.  Now
1066                  * need to check for writes.  We never accept write errors
1067                  * on the replacement, so we don't to check rrdev.
1068                  */
1069                 while (op_is_write(op) && rdev &&
1070                        test_bit(WriteErrorSeen, &rdev->flags)) {
1071                         sector_t first_bad;
1072                         int bad_sectors;
1073                         int bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
1074                                               &first_bad, &bad_sectors);
1075                         if (!bad)
1076                                 break;
1077
1078                         if (bad < 0) {
1079                                 set_bit(BlockedBadBlocks, &rdev->flags);
1080                                 if (!conf->mddev->external &&
1081                                     conf->mddev->sb_flags) {
1082                                         /* It is very unlikely, but we might
1083                                          * still need to write out the
1084                                          * bad block log - better give it
1085                                          * a chance*/
1086                                         md_check_recovery(conf->mddev);
1087                                 }
1088                                 /*
1089                                  * Because md_wait_for_blocked_rdev
1090                                  * will dec nr_pending, we must
1091                                  * increment it first.
1092                                  */
1093                                 atomic_inc(&rdev->nr_pending);
1094                                 md_wait_for_blocked_rdev(rdev, conf->mddev);
1095                         } else {
1096                                 /* Acknowledged bad block - skip the write */
1097                                 rdev_dec_pending(rdev, conf->mddev);
1098                                 rdev = NULL;
1099                         }
1100                 }
1101
1102                 if (rdev) {
1103                         if (s->syncing || s->expanding || s->expanded
1104                             || s->replacing)
1105                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
1106
1107                         set_bit(STRIPE_IO_STARTED, &sh->state);
1108
1109                         bi->bi_bdev = rdev->bdev;
1110                         bio_set_op_attrs(bi, op, op_flags);
1111                         bi->bi_end_io = op_is_write(op)
1112                                 ? raid5_end_write_request
1113                                 : raid5_end_read_request;
1114                         bi->bi_private = sh;
1115
1116                         pr_debug("%s: for %llu schedule op %d on disc %d\n",
1117                                 __func__, (unsigned long long)sh->sector,
1118                                 bi->bi_opf, i);
1119                         atomic_inc(&sh->count);
1120                         if (sh != head_sh)
1121                                 atomic_inc(&head_sh->count);
1122                         if (use_new_offset(conf, sh))
1123                                 bi->bi_iter.bi_sector = (sh->sector
1124                                                  + rdev->new_data_offset);
1125                         else
1126                                 bi->bi_iter.bi_sector = (sh->sector
1127                                                  + rdev->data_offset);
1128                         if (test_bit(R5_ReadNoMerge, &head_sh->dev[i].flags))
1129                                 bi->bi_opf |= REQ_NOMERGE;
1130
1131                         if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
1132                                 WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
1133
1134                         if (!op_is_write(op) &&
1135                             test_bit(R5_InJournal, &sh->dev[i].flags))
1136                                 /*
1137                                  * issuing read for a page in journal, this
1138                                  * must be preparing for prexor in rmw; read
1139                                  * the data into orig_page
1140                                  */
1141                                 sh->dev[i].vec.bv_page = sh->dev[i].orig_page;
1142                         else
1143                                 sh->dev[i].vec.bv_page = sh->dev[i].page;
1144                         bi->bi_vcnt = 1;
1145                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
1146                         bi->bi_io_vec[0].bv_offset = 0;
1147                         bi->bi_iter.bi_size = STRIPE_SIZE;
1148                         /*
1149                          * If this is discard request, set bi_vcnt 0. We don't
1150                          * want to confuse SCSI because SCSI will replace payload
1151                          */
1152                         if (op == REQ_OP_DISCARD)
1153                                 bi->bi_vcnt = 0;
1154                         if (rrdev)
1155                                 set_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags);
1156
1157                         if (conf->mddev->gendisk)
1158                                 trace_block_bio_remap(bdev_get_queue(bi->bi_bdev),
1159                                                       bi, disk_devt(conf->mddev->gendisk),
1160                                                       sh->dev[i].sector);
1161                         if (should_defer && op_is_write(op))
1162                                 bio_list_add(&pending_bios, bi);
1163                         else
1164                                 generic_make_request(bi);
1165                 }
1166                 if (rrdev) {
1167                         if (s->syncing || s->expanding || s->expanded
1168                             || s->replacing)
1169                                 md_sync_acct(rrdev->bdev, STRIPE_SECTORS);
1170
1171                         set_bit(STRIPE_IO_STARTED, &sh->state);
1172
1173                         rbi->bi_bdev = rrdev->bdev;
1174                         bio_set_op_attrs(rbi, op, op_flags);
1175                         BUG_ON(!op_is_write(op));
1176                         rbi->bi_end_io = raid5_end_write_request;
1177                         rbi->bi_private = sh;
1178
1179                         pr_debug("%s: for %llu schedule op %d on "
1180                                  "replacement disc %d\n",
1181                                 __func__, (unsigned long long)sh->sector,
1182                                 rbi->bi_opf, i);
1183                         atomic_inc(&sh->count);
1184                         if (sh != head_sh)
1185                                 atomic_inc(&head_sh->count);
1186                         if (use_new_offset(conf, sh))
1187                                 rbi->bi_iter.bi_sector = (sh->sector
1188                                                   + rrdev->new_data_offset);
1189                         else
1190                                 rbi->bi_iter.bi_sector = (sh->sector
1191                                                   + rrdev->data_offset);
1192                         if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
1193                                 WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
1194                         sh->dev[i].rvec.bv_page = sh->dev[i].page;
1195                         rbi->bi_vcnt = 1;
1196                         rbi->bi_io_vec[0].bv_len = STRIPE_SIZE;
1197                         rbi->bi_io_vec[0].bv_offset = 0;
1198                         rbi->bi_iter.bi_size = STRIPE_SIZE;
1199                         /*
1200                          * If this is discard request, set bi_vcnt 0. We don't
1201                          * want to confuse SCSI because SCSI will replace payload
1202                          */
1203                         if (op == REQ_OP_DISCARD)
1204                                 rbi->bi_vcnt = 0;
1205                         if (conf->mddev->gendisk)
1206                                 trace_block_bio_remap(bdev_get_queue(rbi->bi_bdev),
1207                                                       rbi, disk_devt(conf->mddev->gendisk),
1208                                                       sh->dev[i].sector);
1209                         if (should_defer && op_is_write(op))
1210                                 bio_list_add(&pending_bios, rbi);
1211                         else
1212                                 generic_make_request(rbi);
1213                 }
1214                 if (!rdev && !rrdev) {
1215                         if (op_is_write(op))
1216                                 set_bit(STRIPE_DEGRADED, &sh->state);
1217                         pr_debug("skip op %d on disc %d for sector %llu\n",
1218                                 bi->bi_opf, i, (unsigned long long)sh->sector);
1219                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
1220                         set_bit(STRIPE_HANDLE, &sh->state);
1221                 }
1222
1223                 if (!head_sh->batch_head)
1224                         continue;
1225                 sh = list_first_entry(&sh->batch_list, struct stripe_head,
1226                                       batch_list);
1227                 if (sh != head_sh)
1228                         goto again;
1229         }
1230
1231         if (should_defer && !bio_list_empty(&pending_bios))
1232                 defer_issue_bios(conf, head_sh->sector, &pending_bios);
1233 }
1234
1235 static struct dma_async_tx_descriptor *
1236 async_copy_data(int frombio, struct bio *bio, struct page **page,
1237         sector_t sector, struct dma_async_tx_descriptor *tx,
1238         struct stripe_head *sh, int no_skipcopy)
1239 {
1240         struct bio_vec bvl;
1241         struct bvec_iter iter;
1242         struct page *bio_page;
1243         int page_offset;
1244         struct async_submit_ctl submit;
1245         enum async_tx_flags flags = 0;
1246
1247         if (bio->bi_iter.bi_sector >= sector)
1248                 page_offset = (signed)(bio->bi_iter.bi_sector - sector) * 512;
1249         else
1250                 page_offset = (signed)(sector - bio->bi_iter.bi_sector) * -512;
1251
1252         if (frombio)
1253                 flags |= ASYNC_TX_FENCE;
1254         init_async_submit(&submit, flags, tx, NULL, NULL, NULL);
1255
1256         bio_for_each_segment(bvl, bio, iter) {
1257                 int len = bvl.bv_len;
1258                 int clen;
1259                 int b_offset = 0;
1260
1261                 if (page_offset < 0) {
1262                         b_offset = -page_offset;
1263                         page_offset += b_offset;
1264                         len -= b_offset;
1265                 }
1266
1267                 if (len > 0 && page_offset + len > STRIPE_SIZE)
1268                         clen = STRIPE_SIZE - page_offset;
1269                 else
1270                         clen = len;
1271
1272                 if (clen > 0) {
1273                         b_offset += bvl.bv_offset;
1274                         bio_page = bvl.bv_page;
1275                         if (frombio) {
1276                                 if (sh->raid_conf->skip_copy &&
1277                                     b_offset == 0 && page_offset == 0 &&
1278                                     clen == STRIPE_SIZE &&
1279                                     !no_skipcopy)
1280                                         *page = bio_page;
1281                                 else
1282                                         tx = async_memcpy(*page, bio_page, page_offset,
1283                                                   b_offset, clen, &submit);
1284                         } else
1285                                 tx = async_memcpy(bio_page, *page, b_offset,
1286                                                   page_offset, clen, &submit);
1287                 }
1288                 /* chain the operations */
1289                 submit.depend_tx = tx;
1290
1291                 if (clen < len) /* hit end of page */
1292                         break;
1293                 page_offset +=  len;
1294         }
1295
1296         return tx;
1297 }
1298
1299 static void ops_complete_biofill(void *stripe_head_ref)
1300 {
1301         struct stripe_head *sh = stripe_head_ref;
1302         int i;
1303
1304         pr_debug("%s: stripe %llu\n", __func__,
1305                 (unsigned long long)sh->sector);
1306
1307         /* clear completed biofills */
1308         for (i = sh->disks; i--; ) {
1309                 struct r5dev *dev = &sh->dev[i];
1310
1311                 /* acknowledge completion of a biofill operation */
1312                 /* and check if we need to reply to a read request,
1313                  * new R5_Wantfill requests are held off until
1314                  * !STRIPE_BIOFILL_RUN
1315                  */
1316                 if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
1317                         struct bio *rbi, *rbi2;
1318
1319                         BUG_ON(!dev->read);
1320                         rbi = dev->read;
1321                         dev->read = NULL;
1322                         while (rbi && rbi->bi_iter.bi_sector <
1323                                 dev->sector + STRIPE_SECTORS) {
1324                                 rbi2 = r5_next_bio(rbi, dev->sector);
1325                                 bio_endio(rbi);
1326                                 rbi = rbi2;
1327                         }
1328                 }
1329         }
1330         clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
1331
1332         set_bit(STRIPE_HANDLE, &sh->state);
1333         raid5_release_stripe(sh);
1334 }
1335
1336 static void ops_run_biofill(struct stripe_head *sh)
1337 {
1338         struct dma_async_tx_descriptor *tx = NULL;
1339         struct async_submit_ctl submit;
1340         int i;
1341
1342         BUG_ON(sh->batch_head);
1343         pr_debug("%s: stripe %llu\n", __func__,
1344                 (unsigned long long)sh->sector);
1345
1346         for (i = sh->disks; i--; ) {
1347                 struct r5dev *dev = &sh->dev[i];
1348                 if (test_bit(R5_Wantfill, &dev->flags)) {
1349                         struct bio *rbi;
1350                         spin_lock_irq(&sh->stripe_lock);
1351                         dev->read = rbi = dev->toread;
1352                         dev->toread = NULL;
1353                         spin_unlock_irq(&sh->stripe_lock);
1354                         while (rbi && rbi->bi_iter.bi_sector <
1355                                 dev->sector + STRIPE_SECTORS) {
1356                                 tx = async_copy_data(0, rbi, &dev->page,
1357                                                      dev->sector, tx, sh, 0);
1358                                 rbi = r5_next_bio(rbi, dev->sector);
1359                         }
1360                 }
1361         }
1362
1363         atomic_inc(&sh->count);
1364         init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_biofill, sh, NULL);
1365         async_trigger_callback(&submit);
1366 }
1367
1368 static void mark_target_uptodate(struct stripe_head *sh, int target)
1369 {
1370         struct r5dev *tgt;
1371
1372         if (target < 0)
1373                 return;
1374
1375         tgt = &sh->dev[target];
1376         set_bit(R5_UPTODATE, &tgt->flags);
1377         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1378         clear_bit(R5_Wantcompute, &tgt->flags);
1379 }
1380
1381 static void ops_complete_compute(void *stripe_head_ref)
1382 {
1383         struct stripe_head *sh = stripe_head_ref;
1384
1385         pr_debug("%s: stripe %llu\n", __func__,
1386                 (unsigned long long)sh->sector);
1387
1388         /* mark the computed target(s) as uptodate */
1389         mark_target_uptodate(sh, sh->ops.target);
1390         mark_target_uptodate(sh, sh->ops.target2);
1391
1392         clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
1393         if (sh->check_state == check_state_compute_run)
1394                 sh->check_state = check_state_compute_result;
1395         set_bit(STRIPE_HANDLE, &sh->state);
1396         raid5_release_stripe(sh);
1397 }
1398
1399 /* return a pointer to the address conversion region of the scribble buffer */
1400 static addr_conv_t *to_addr_conv(struct stripe_head *sh,
1401                                  struct raid5_percpu *percpu, int i)
1402 {
1403         void *addr;
1404
1405         addr = flex_array_get(percpu->scribble, i);
1406         return addr + sizeof(struct page *) * (sh->disks + 2);
1407 }
1408
1409 /* return a pointer to the address conversion region of the scribble buffer */
1410 static struct page **to_addr_page(struct raid5_percpu *percpu, int i)
1411 {
1412         void *addr;
1413
1414         addr = flex_array_get(percpu->scribble, i);
1415         return addr;
1416 }
1417
1418 static struct dma_async_tx_descriptor *
1419 ops_run_compute5(struct stripe_head *sh, struct raid5_percpu *percpu)
1420 {
1421         int disks = sh->disks;
1422         struct page **xor_srcs = to_addr_page(percpu, 0);
1423         int target = sh->ops.target;
1424         struct r5dev *tgt = &sh->dev[target];
1425         struct page *xor_dest = tgt->page;
1426         int count = 0;
1427         struct dma_async_tx_descriptor *tx;
1428         struct async_submit_ctl submit;
1429         int i;
1430
1431         BUG_ON(sh->batch_head);
1432
1433         pr_debug("%s: stripe %llu block: %d\n",
1434                 __func__, (unsigned long long)sh->sector, target);
1435         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1436
1437         for (i = disks; i--; )
1438                 if (i != target)
1439                         xor_srcs[count++] = sh->dev[i].page;
1440
1441         atomic_inc(&sh->count);
1442
1443         init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, NULL,
1444                           ops_complete_compute, sh, to_addr_conv(sh, percpu, 0));
1445         if (unlikely(count == 1))
1446                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1447         else
1448                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1449
1450         return tx;
1451 }
1452
1453 /* set_syndrome_sources - populate source buffers for gen_syndrome
1454  * @srcs - (struct page *) array of size sh->disks
1455  * @sh - stripe_head to parse
1456  *
1457  * Populates srcs in proper layout order for the stripe and returns the
1458  * 'count' of sources to be used in a call to async_gen_syndrome.  The P
1459  * destination buffer is recorded in srcs[count] and the Q destination
1460  * is recorded in srcs[count+1]].
1461  */
1462 static int set_syndrome_sources(struct page **srcs,
1463                                 struct stripe_head *sh,
1464                                 int srctype)
1465 {
1466         int disks = sh->disks;
1467         int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
1468         int d0_idx = raid6_d0(sh);
1469         int count;
1470         int i;
1471
1472         for (i = 0; i < disks; i++)
1473                 srcs[i] = NULL;
1474
1475         count = 0;
1476         i = d0_idx;
1477         do {
1478                 int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1479                 struct r5dev *dev = &sh->dev[i];
1480
1481                 if (i == sh->qd_idx || i == sh->pd_idx ||
1482                     (srctype == SYNDROME_SRC_ALL) ||
1483                     (srctype == SYNDROME_SRC_WANT_DRAIN &&
1484                      (test_bit(R5_Wantdrain, &dev->flags) ||
1485                       test_bit(R5_InJournal, &dev->flags))) ||
1486                     (srctype == SYNDROME_SRC_WRITTEN &&
1487                      (dev->written ||
1488                       test_bit(R5_InJournal, &dev->flags)))) {
1489                         if (test_bit(R5_InJournal, &dev->flags))
1490                                 srcs[slot] = sh->dev[i].orig_page;
1491                         else
1492                                 srcs[slot] = sh->dev[i].page;
1493                 }
1494                 i = raid6_next_disk(i, disks);
1495         } while (i != d0_idx);
1496
1497         return syndrome_disks;
1498 }
1499
1500 static struct dma_async_tx_descriptor *
1501 ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
1502 {
1503         int disks = sh->disks;
1504         struct page **blocks = to_addr_page(percpu, 0);
1505         int target;
1506         int qd_idx = sh->qd_idx;
1507         struct dma_async_tx_descriptor *tx;
1508         struct async_submit_ctl submit;
1509         struct r5dev *tgt;
1510         struct page *dest;
1511         int i;
1512         int count;
1513
1514         BUG_ON(sh->batch_head);
1515         if (sh->ops.target < 0)
1516                 target = sh->ops.target2;
1517         else if (sh->ops.target2 < 0)
1518                 target = sh->ops.target;
1519         else
1520                 /* we should only have one valid target */
1521                 BUG();
1522         BUG_ON(target < 0);
1523         pr_debug("%s: stripe %llu block: %d\n",
1524                 __func__, (unsigned long long)sh->sector, target);
1525
1526         tgt = &sh->dev[target];
1527         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1528         dest = tgt->page;
1529
1530         atomic_inc(&sh->count);
1531
1532         if (target == qd_idx) {
1533                 count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_ALL);
1534                 blocks[count] = NULL; /* regenerating p is not necessary */
1535                 BUG_ON(blocks[count+1] != dest); /* q should already be set */
1536                 init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1537                                   ops_complete_compute, sh,
1538                                   to_addr_conv(sh, percpu, 0));
1539                 tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE, &submit);
1540         } else {
1541                 /* Compute any data- or p-drive using XOR */
1542                 count = 0;
1543                 for (i = disks; i-- ; ) {
1544                         if (i == target || i == qd_idx)
1545                                 continue;
1546                         blocks[count++] = sh->dev[i].page;
1547                 }
1548
1549                 init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1550                                   NULL, ops_complete_compute, sh,
1551                                   to_addr_conv(sh, percpu, 0));
1552                 tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE, &submit);
1553         }
1554
1555         return tx;
1556 }
1557
1558 static struct dma_async_tx_descriptor *
1559 ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
1560 {
1561         int i, count, disks = sh->disks;
1562         int syndrome_disks = sh->ddf_layout ? disks : disks-2;
1563         int d0_idx = raid6_d0(sh);
1564         int faila = -1, failb = -1;
1565         int target = sh->ops.target;
1566         int target2 = sh->ops.target2;
1567         struct r5dev *tgt = &sh->dev[target];
1568         struct r5dev *tgt2 = &sh->dev[target2];
1569         struct dma_async_tx_descriptor *tx;
1570         struct page **blocks = to_addr_page(percpu, 0);
1571         struct async_submit_ctl submit;
1572
1573         BUG_ON(sh->batch_head);
1574         pr_debug("%s: stripe %llu block1: %d block2: %d\n",
1575                  __func__, (unsigned long long)sh->sector, target, target2);
1576         BUG_ON(target < 0 || target2 < 0);
1577         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1578         BUG_ON(!test_bit(R5_Wantcompute, &tgt2->flags));
1579
1580         /* we need to open-code set_syndrome_sources to handle the
1581          * slot number conversion for 'faila' and 'failb'
1582          */
1583         for (i = 0; i < disks ; i++)
1584                 blocks[i] = NULL;
1585         count = 0;
1586         i = d0_idx;
1587         do {
1588                 int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1589
1590                 blocks[slot] = sh->dev[i].page;
1591
1592                 if (i == target)
1593                         faila = slot;
1594                 if (i == target2)
1595                         failb = slot;
1596                 i = raid6_next_disk(i, disks);
1597         } while (i != d0_idx);
1598
1599         BUG_ON(faila == failb);
1600         if (failb < faila)
1601                 swap(faila, failb);
1602         pr_debug("%s: stripe: %llu faila: %d failb: %d\n",
1603                  __func__, (unsigned long long)sh->sector, faila, failb);
1604
1605         atomic_inc(&sh->count);
1606
1607         if (failb == syndrome_disks+1) {
1608                 /* Q disk is one of the missing disks */
1609                 if (faila == syndrome_disks) {
1610                         /* Missing P+Q, just recompute */
1611                         init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1612                                           ops_complete_compute, sh,
1613                                           to_addr_conv(sh, percpu, 0));
1614                         return async_gen_syndrome(blocks, 0, syndrome_disks+2,
1615                                                   STRIPE_SIZE, &submit);
1616                 } else {
1617                         struct page *dest;
1618                         int data_target;
1619                         int qd_idx = sh->qd_idx;
1620
1621                         /* Missing D+Q: recompute D from P, then recompute Q */
1622                         if (target == qd_idx)
1623                                 data_target = target2;
1624                         else
1625                                 data_target = target;
1626
1627                         count = 0;
1628                         for (i = disks; i-- ; ) {
1629                                 if (i == data_target || i == qd_idx)
1630                                         continue;
1631                                 blocks[count++] = sh->dev[i].page;
1632                         }
1633                         dest = sh->dev[data_target].page;
1634                         init_async_submit(&submit,
1635                                           ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1636                                           NULL, NULL, NULL,
1637                                           to_addr_conv(sh, percpu, 0));
1638                         tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE,
1639                                        &submit);
1640
1641                         count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_ALL);
1642                         init_async_submit(&submit, ASYNC_TX_FENCE, tx,
1643                                           ops_complete_compute, sh,
1644                                           to_addr_conv(sh, percpu, 0));
1645                         return async_gen_syndrome(blocks, 0, count+2,
1646                                                   STRIPE_SIZE, &submit);
1647                 }
1648         } else {
1649                 init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1650                                   ops_complete_compute, sh,
1651                                   to_addr_conv(sh, percpu, 0));
1652                 if (failb == syndrome_disks) {
1653                         /* We're missing D+P. */
1654                         return async_raid6_datap_recov(syndrome_disks+2,
1655                                                        STRIPE_SIZE, faila,
1656                                                        blocks, &submit);
1657                 } else {
1658                         /* We're missing D+D. */
1659                         return async_raid6_2data_recov(syndrome_disks+2,
1660                                                        STRIPE_SIZE, faila, failb,
1661                                                        blocks, &submit);
1662                 }
1663         }
1664 }
1665
1666 static void ops_complete_prexor(void *stripe_head_ref)
1667 {
1668         struct stripe_head *sh = stripe_head_ref;
1669
1670         pr_debug("%s: stripe %llu\n", __func__,
1671                 (unsigned long long)sh->sector);
1672
1673         if (r5c_is_writeback(sh->raid_conf->log))
1674                 /*
1675                  * raid5-cache write back uses orig_page during prexor.
1676                  * After prexor, it is time to free orig_page
1677                  */
1678                 r5c_release_extra_page(sh);
1679 }
1680
1681 static struct dma_async_tx_descriptor *
1682 ops_run_prexor5(struct stripe_head *sh, struct raid5_percpu *percpu,
1683                 struct dma_async_tx_descriptor *tx)
1684 {
1685         int disks = sh->disks;
1686         struct page **xor_srcs = to_addr_page(percpu, 0);
1687         int count = 0, pd_idx = sh->pd_idx, i;
1688         struct async_submit_ctl submit;
1689
1690         /* existing parity data subtracted */
1691         struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1692
1693         BUG_ON(sh->batch_head);
1694         pr_debug("%s: stripe %llu\n", __func__,
1695                 (unsigned long long)sh->sector);
1696
1697         for (i = disks; i--; ) {
1698                 struct r5dev *dev = &sh->dev[i];
1699                 /* Only process blocks that are known to be uptodate */
1700                 if (test_bit(R5_InJournal, &dev->flags))
1701                         xor_srcs[count++] = dev->orig_page;
1702                 else if (test_bit(R5_Wantdrain, &dev->flags))
1703                         xor_srcs[count++] = dev->page;
1704         }
1705
1706         init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
1707                           ops_complete_prexor, sh, to_addr_conv(sh, percpu, 0));
1708         tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1709
1710         return tx;
1711 }
1712
1713 static struct dma_async_tx_descriptor *
1714 ops_run_prexor6(struct stripe_head *sh, struct raid5_percpu *percpu,
1715                 struct dma_async_tx_descriptor *tx)
1716 {
1717         struct page **blocks = to_addr_page(percpu, 0);
1718         int count;
1719         struct async_submit_ctl submit;
1720
1721         pr_debug("%s: stripe %llu\n", __func__,
1722                 (unsigned long long)sh->sector);
1723
1724         count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_WANT_DRAIN);
1725
1726         init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_PQ_XOR_DST, tx,
1727                           ops_complete_prexor, sh, to_addr_conv(sh, percpu, 0));
1728         tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1729
1730         return tx;
1731 }
1732
1733 static struct dma_async_tx_descriptor *
1734 ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
1735 {
1736         struct r5conf *conf = sh->raid_conf;
1737         int disks = sh->disks;
1738         int i;
1739         struct stripe_head *head_sh = sh;
1740
1741         pr_debug("%s: stripe %llu\n", __func__,
1742                 (unsigned long long)sh->sector);
1743
1744         for (i = disks; i--; ) {
1745                 struct r5dev *dev;
1746                 struct bio *chosen;
1747
1748                 sh = head_sh;
1749                 if (test_and_clear_bit(R5_Wantdrain, &head_sh->dev[i].flags)) {
1750                         struct bio *wbi;
1751
1752 again:
1753                         dev = &sh->dev[i];
1754                         /*
1755                          * clear R5_InJournal, so when rewriting a page in
1756                          * journal, it is not skipped by r5l_log_stripe()
1757                          */
1758                         clear_bit(R5_InJournal, &dev->flags);
1759                         spin_lock_irq(&sh->stripe_lock);
1760                         chosen = dev->towrite;
1761                         dev->towrite = NULL;
1762                         sh->overwrite_disks = 0;
1763                         BUG_ON(dev->written);
1764                         wbi = dev->written = chosen;
1765                         spin_unlock_irq(&sh->stripe_lock);
1766                         WARN_ON(dev->page != dev->orig_page);
1767
1768                         while (wbi && wbi->bi_iter.bi_sector <
1769                                 dev->sector + STRIPE_SECTORS) {
1770                                 if (wbi->bi_opf & REQ_FUA)
1771                                         set_bit(R5_WantFUA, &dev->flags);
1772                                 if (wbi->bi_opf & REQ_SYNC)
1773                                         set_bit(R5_SyncIO, &dev->flags);
1774                                 if (bio_op(wbi) == REQ_OP_DISCARD)
1775                                         set_bit(R5_Discard, &dev->flags);
1776                                 else {
1777                                         tx = async_copy_data(1, wbi, &dev->page,
1778                                                              dev->sector, tx, sh,
1779                                                              r5c_is_writeback(conf->log));
1780                                         if (dev->page != dev->orig_page &&
1781                                             !r5c_is_writeback(conf->log)) {
1782                                                 set_bit(R5_SkipCopy, &dev->flags);
1783                                                 clear_bit(R5_UPTODATE, &dev->flags);
1784                                                 clear_bit(R5_OVERWRITE, &dev->flags);
1785                                         }
1786                                 }
1787                                 wbi = r5_next_bio(wbi, dev->sector);
1788                         }
1789
1790                         if (head_sh->batch_head) {
1791                                 sh = list_first_entry(&sh->batch_list,
1792                                                       struct stripe_head,
1793                                                       batch_list);
1794                                 if (sh == head_sh)
1795                                         continue;
1796                                 goto again;
1797                         }
1798                 }
1799         }
1800
1801         return tx;
1802 }
1803
1804 static void ops_complete_reconstruct(void *stripe_head_ref)
1805 {
1806         struct stripe_head *sh = stripe_head_ref;
1807         int disks = sh->disks;
1808         int pd_idx = sh->pd_idx;
1809         int qd_idx = sh->qd_idx;
1810         int i;
1811         bool fua = false, sync = false, discard = false;
1812
1813         pr_debug("%s: stripe %llu\n", __func__,
1814                 (unsigned long long)sh->sector);
1815
1816         for (i = disks; i--; ) {
1817                 fua |= test_bit(R5_WantFUA, &sh->dev[i].flags);
1818                 sync |= test_bit(R5_SyncIO, &sh->dev[i].flags);
1819                 discard |= test_bit(R5_Discard, &sh->dev[i].flags);
1820         }
1821
1822         for (i = disks; i--; ) {
1823                 struct r5dev *dev = &sh->dev[i];
1824
1825                 if (dev->written || i == pd_idx || i == qd_idx) {
1826                         if (!discard && !test_bit(R5_SkipCopy, &dev->flags))
1827                                 set_bit(R5_UPTODATE, &dev->flags);
1828                         if (fua)
1829                                 set_bit(R5_WantFUA, &dev->flags);
1830                         if (sync)
1831                                 set_bit(R5_SyncIO, &dev->flags);
1832                 }
1833         }
1834
1835         if (sh->reconstruct_state == reconstruct_state_drain_run)
1836                 sh->reconstruct_state = reconstruct_state_drain_result;
1837         else if (sh->reconstruct_state == reconstruct_state_prexor_drain_run)
1838                 sh->reconstruct_state = reconstruct_state_prexor_drain_result;
1839         else {
1840                 BUG_ON(sh->reconstruct_state != reconstruct_state_run);
1841                 sh->reconstruct_state = reconstruct_state_result;
1842         }
1843
1844         set_bit(STRIPE_HANDLE, &sh->state);
1845         raid5_release_stripe(sh);
1846 }
1847
1848 static void
1849 ops_run_reconstruct5(struct stripe_head *sh, struct raid5_percpu *percpu,
1850                      struct dma_async_tx_descriptor *tx)
1851 {
1852         int disks = sh->disks;
1853         struct page **xor_srcs;
1854         struct async_submit_ctl submit;
1855         int count, pd_idx = sh->pd_idx, i;
1856         struct page *xor_dest;
1857         int prexor = 0;
1858         unsigned long flags;
1859         int j = 0;
1860         struct stripe_head *head_sh = sh;
1861         int last_stripe;
1862
1863         pr_debug("%s: stripe %llu\n", __func__,
1864                 (unsigned long long)sh->sector);
1865
1866         for (i = 0; i < sh->disks; i++) {
1867                 if (pd_idx == i)
1868                         continue;
1869                 if (!test_bit(R5_Discard, &sh->dev[i].flags))
1870                         break;
1871         }
1872         if (i >= sh->disks) {
1873                 atomic_inc(&sh->count);
1874                 set_bit(R5_Discard, &sh->dev[pd_idx].flags);
1875                 ops_complete_reconstruct(sh);
1876                 return;
1877         }
1878 again:
1879         count = 0;
1880         xor_srcs = to_addr_page(percpu, j);
1881         /* check if prexor is active which means only process blocks
1882          * that are part of a read-modify-write (written)
1883          */
1884         if (head_sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1885                 prexor = 1;
1886                 xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1887                 for (i = disks; i--; ) {
1888                         struct r5dev *dev = &sh->dev[i];
1889                         if (head_sh->dev[i].written ||
1890                             test_bit(R5_InJournal, &head_sh->dev[i].flags))
1891                                 xor_srcs[count++] = dev->page;
1892                 }
1893         } else {
1894                 xor_dest = sh->dev[pd_idx].page;
1895                 for (i = disks; i--; ) {
1896                         struct r5dev *dev = &sh->dev[i];
1897                         if (i != pd_idx)
1898                                 xor_srcs[count++] = dev->page;
1899                 }
1900         }
1901
1902         /* 1/ if we prexor'd then the dest is reused as a source
1903          * 2/ if we did not prexor then we are redoing the parity
1904          * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
1905          * for the synchronous xor case
1906          */
1907         last_stripe = !head_sh->batch_head ||
1908                 list_first_entry(&sh->batch_list,
1909                                  struct stripe_head, batch_list) == head_sh;
1910         if (last_stripe) {
1911                 flags = ASYNC_TX_ACK |
1912                         (prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
1913
1914                 atomic_inc(&head_sh->count);
1915                 init_async_submit(&submit, flags, tx, ops_complete_reconstruct, head_sh,
1916                                   to_addr_conv(sh, percpu, j));
1917         } else {
1918                 flags = prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST;
1919                 init_async_submit(&submit, flags, tx, NULL, NULL,
1920                                   to_addr_conv(sh, percpu, j));
1921         }
1922
1923         if (unlikely(count == 1))
1924                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1925         else
1926                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1927         if (!last_stripe) {
1928                 j++;
1929                 sh = list_first_entry(&sh->batch_list, struct stripe_head,
1930                                       batch_list);
1931                 goto again;
1932         }
1933 }
1934
1935 static void
1936 ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
1937                      struct dma_async_tx_descriptor *tx)
1938 {
1939         struct async_submit_ctl submit;
1940         struct page **blocks;
1941         int count, i, j = 0;
1942         struct stripe_head *head_sh = sh;
1943         int last_stripe;
1944         int synflags;
1945         unsigned long txflags;
1946
1947         pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
1948
1949         for (i = 0; i < sh->disks; i++) {
1950                 if (sh->pd_idx == i || sh->qd_idx == i)
1951                         continue;
1952                 if (!test_bit(R5_Discard, &sh->dev[i].flags))
1953                         break;
1954         }
1955         if (i >= sh->disks) {
1956                 atomic_inc(&sh->count);
1957                 set_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
1958                 set_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
1959                 ops_complete_reconstruct(sh);
1960                 return;
1961         }
1962
1963 again:
1964         blocks = to_addr_page(percpu, j);
1965
1966         if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1967                 synflags = SYNDROME_SRC_WRITTEN;
1968                 txflags = ASYNC_TX_ACK | ASYNC_TX_PQ_XOR_DST;
1969         } else {
1970                 synflags = SYNDROME_SRC_ALL;
1971                 txflags = ASYNC_TX_ACK;
1972         }
1973
1974         count = set_syndrome_sources(blocks, sh, synflags);
1975         last_stripe = !head_sh->batch_head ||
1976                 list_first_entry(&sh->batch_list,
1977                                  struct stripe_head, batch_list) == head_sh;
1978
1979         if (last_stripe) {
1980                 atomic_inc(&head_sh->count);
1981                 init_async_submit(&submit, txflags, tx, ops_complete_reconstruct,
1982                                   head_sh, to_addr_conv(sh, percpu, j));
1983         } else
1984                 init_async_submit(&submit, 0, tx, NULL, NULL,
1985                                   to_addr_conv(sh, percpu, j));
1986         tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1987         if (!last_stripe) {
1988                 j++;
1989                 sh = list_first_entry(&sh->batch_list, struct stripe_head,
1990                                       batch_list);
1991                 goto again;
1992         }
1993 }
1994
1995 static void ops_complete_check(void *stripe_head_ref)
1996 {
1997         struct stripe_head *sh = stripe_head_ref;
1998
1999         pr_debug("%s: stripe %llu\n", __func__,
2000                 (unsigned long long)sh->sector);
2001
2002         sh->check_state = check_state_check_result;
2003         set_bit(STRIPE_HANDLE, &sh->state);
2004         raid5_release_stripe(sh);
2005 }
2006
2007 static void ops_run_check_p(struct stripe_head *sh, struct raid5_percpu *percpu)
2008 {
2009         int disks = sh->disks;
2010         int pd_idx = sh->pd_idx;
2011         int qd_idx = sh->qd_idx;
2012         struct page *xor_dest;
2013         struct page **xor_srcs = to_addr_page(percpu, 0);
2014         struct dma_async_tx_descriptor *tx;
2015         struct async_submit_ctl submit;
2016         int count;
2017         int i;
2018
2019         pr_debug("%s: stripe %llu\n", __func__,
2020                 (unsigned long long)sh->sector);
2021
2022         BUG_ON(sh->batch_head);
2023         count = 0;
2024         xor_dest = sh->dev[pd_idx].page;
2025         xor_srcs[count++] = xor_dest;
2026         for (i = disks; i--; ) {
2027                 if (i == pd_idx || i == qd_idx)
2028                         continue;
2029                 xor_srcs[count++] = sh->dev[i].page;
2030         }
2031
2032         init_async_submit(&submit, 0, NULL, NULL, NULL,
2033                           to_addr_conv(sh, percpu, 0));
2034         tx = async_xor_val(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
2035                            &sh->ops.zero_sum_result, &submit);
2036
2037         atomic_inc(&sh->count);
2038         init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_check, sh, NULL);
2039         tx = async_trigger_callback(&submit);
2040 }
2041
2042 static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu, int checkp)
2043 {
2044         struct page **srcs = to_addr_page(percpu, 0);
2045         struct async_submit_ctl submit;
2046         int count;
2047
2048         pr_debug("%s: stripe %llu checkp: %d\n", __func__,
2049                 (unsigned long long)sh->sector, checkp);
2050
2051         BUG_ON(sh->batch_head);
2052         count = set_syndrome_sources(srcs, sh, SYNDROME_SRC_ALL);
2053         if (!checkp)
2054                 srcs[count] = NULL;
2055
2056         atomic_inc(&sh->count);
2057         init_async_submit(&submit, ASYNC_TX_ACK, NULL, ops_complete_check,
2058                           sh, to_addr_conv(sh, percpu, 0));
2059         async_syndrome_val(srcs, 0, count+2, STRIPE_SIZE,
2060                            &sh->ops.zero_sum_result, percpu->spare_page, &submit);
2061 }
2062
2063 static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
2064 {
2065         int overlap_clear = 0, i, disks = sh->disks;
2066         struct dma_async_tx_descriptor *tx = NULL;
2067         struct r5conf *conf = sh->raid_conf;
2068         int level = conf->level;
2069         struct raid5_percpu *percpu;
2070         unsigned long cpu;
2071
2072         cpu = get_cpu();
2073         percpu = per_cpu_ptr(conf->percpu, cpu);
2074         if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
2075                 ops_run_biofill(sh);
2076                 overlap_clear++;
2077         }
2078
2079         if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
2080                 if (level < 6)
2081                         tx = ops_run_compute5(sh, percpu);
2082                 else {
2083                         if (sh->ops.target2 < 0 || sh->ops.target < 0)
2084                                 tx = ops_run_compute6_1(sh, percpu);
2085                         else
2086                                 tx = ops_run_compute6_2(sh, percpu);
2087                 }
2088                 /* terminate the chain if reconstruct is not set to be run */
2089                 if (tx && !test_bit(STRIPE_OP_RECONSTRUCT, &ops_request))
2090                         async_tx_ack(tx);
2091         }
2092
2093         if (test_bit(STRIPE_OP_PARTIAL_PARITY, &ops_request))
2094                 tx = ops_run_partial_parity(sh, percpu, tx);
2095
2096         if (test_bit(STRIPE_OP_PREXOR, &ops_request)) {
2097                 if (level < 6)
2098                         tx = ops_run_prexor5(sh, percpu, tx);
2099                 else
2100                         tx = ops_run_prexor6(sh, percpu, tx);
2101         }
2102
2103         if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
2104                 tx = ops_run_biodrain(sh, tx);
2105                 overlap_clear++;
2106         }
2107
2108         if (test_bit(STRIPE_OP_RECONSTRUCT, &ops_request)) {
2109                 if (level < 6)
2110                         ops_run_reconstruct5(sh, percpu, tx);
2111                 else
2112                         ops_run_reconstruct6(sh, percpu, tx);
2113         }
2114
2115         if (test_bit(STRIPE_OP_CHECK, &ops_request)) {
2116                 if (sh->check_state == check_state_run)
2117                         ops_run_check_p(sh, percpu);
2118                 else if (sh->check_state == check_state_run_q)
2119                         ops_run_check_pq(sh, percpu, 0);
2120                 else if (sh->check_state == check_state_run_pq)
2121                         ops_run_check_pq(sh, percpu, 1);
2122                 else
2123                         BUG();
2124         }
2125
2126         if (overlap_clear && !sh->batch_head)
2127                 for (i = disks; i--; ) {
2128                         struct r5dev *dev = &sh->dev[i];
2129                         if (test_and_clear_bit(R5_Overlap, &dev->flags))
2130                                 wake_up(&sh->raid_conf->wait_for_overlap);
2131                 }
2132         put_cpu();
2133 }
2134
2135 static struct stripe_head *alloc_stripe(struct kmem_cache *sc, gfp_t gfp,
2136         int disks)
2137 {
2138         struct stripe_head *sh;
2139         int i;
2140
2141         sh = kmem_cache_zalloc(sc, gfp);
2142         if (sh) {
2143                 spin_lock_init(&sh->stripe_lock);
2144                 spin_lock_init(&sh->batch_lock);
2145                 INIT_LIST_HEAD(&sh->batch_list);
2146                 INIT_LIST_HEAD(&sh->lru);
2147                 INIT_LIST_HEAD(&sh->r5c);
2148                 INIT_LIST_HEAD(&sh->log_list);
2149                 atomic_set(&sh->count, 1);
2150                 sh->log_start = MaxSector;
2151                 for (i = 0; i < disks; i++) {
2152                         struct r5dev *dev = &sh->dev[i];
2153
2154                         bio_init(&dev->req, &dev->vec, 1);
2155                         bio_init(&dev->rreq, &dev->rvec, 1);
2156                 }
2157         }
2158         return sh;
2159 }
2160 static int grow_one_stripe(struct r5conf *conf, gfp_t gfp)
2161 {
2162         struct stripe_head *sh;
2163
2164         sh = alloc_stripe(conf->slab_cache, gfp, conf->pool_size);
2165         if (!sh)
2166                 return 0;
2167
2168         sh->raid_conf = conf;
2169
2170         if (grow_buffers(sh, gfp)) {
2171                 shrink_buffers(sh);
2172                 kmem_cache_free(conf->slab_cache, sh);
2173                 return 0;
2174         }
2175         sh->hash_lock_index =
2176                 conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS;
2177         /* we just created an active stripe so... */
2178         atomic_inc(&conf->active_stripes);
2179
2180         raid5_release_stripe(sh);
2181         conf->max_nr_stripes++;
2182         return 1;
2183 }
2184
2185 static int grow_stripes(struct r5conf *conf, int num)
2186 {
2187         struct kmem_cache *sc;
2188         int devs = max(conf->raid_disks, conf->previous_raid_disks);
2189
2190         if (conf->mddev->gendisk)
2191                 sprintf(conf->cache_name[0],
2192                         "raid%d-%s", conf->level, mdname(conf->mddev));
2193         else
2194                 sprintf(conf->cache_name[0],
2195                         "raid%d-%p", conf->level, conf->mddev);
2196         sprintf(conf->cache_name[1], "%s-alt", conf->cache_name[0]);
2197
2198         conf->active_name = 0;
2199         sc = kmem_cache_create(conf->cache_name[conf->active_name],
2200                                sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
2201                                0, 0, NULL);
2202         if (!sc)
2203                 return 1;
2204         conf->slab_cache = sc;
2205         conf->pool_size = devs;
2206         while (num--)
2207                 if (!grow_one_stripe(conf, GFP_KERNEL))
2208                         return 1;
2209
2210         return 0;
2211 }
2212
2213 /**
2214  * scribble_len - return the required size of the scribble region
2215  * @num - total number of disks in the array
2216  *
2217  * The size must be enough to contain:
2218  * 1/ a struct page pointer for each device in the array +2
2219  * 2/ room to convert each entry in (1) to its corresponding dma
2220  *    (dma_map_page()) or page (page_address()) address.
2221  *
2222  * Note: the +2 is for the destination buffers of the ddf/raid6 case where we
2223  * calculate over all devices (not just the data blocks), using zeros in place
2224  * of the P and Q blocks.
2225  */
2226 static struct flex_array *scribble_alloc(int num, int cnt, gfp_t flags)
2227 {
2228         struct flex_array *ret;
2229         size_t len;
2230
2231         len = sizeof(struct page *) * (num+2) + sizeof(addr_conv_t) * (num+2);
2232         ret = flex_array_alloc(len, cnt, flags);
2233         if (!ret)
2234                 return NULL;
2235         /* always prealloc all elements, so no locking is required */
2236         if (flex_array_prealloc(ret, 0, cnt, flags)) {
2237                 flex_array_free(ret);
2238                 return NULL;
2239         }
2240         return ret;
2241 }
2242
2243 static int resize_chunks(struct r5conf *conf, int new_disks, int new_sectors)
2244 {
2245         unsigned long cpu;
2246         int err = 0;
2247
2248         /*
2249          * Never shrink. And mddev_suspend() could deadlock if this is called
2250          * from raid5d. In that case, scribble_disks and scribble_sectors
2251          * should equal to new_disks and new_sectors
2252          */
2253         if (conf->scribble_disks >= new_disks &&
2254             conf->scribble_sectors >= new_sectors)
2255                 return 0;
2256         mddev_suspend(conf->mddev);
2257         get_online_cpus();
2258         for_each_present_cpu(cpu) {
2259                 struct raid5_percpu *percpu;
2260                 struct flex_array *scribble;
2261
2262                 percpu = per_cpu_ptr(conf->percpu, cpu);
2263                 scribble = scribble_alloc(new_disks,
2264                                           new_sectors / STRIPE_SECTORS,
2265                                           GFP_NOIO);
2266
2267                 if (scribble) {
2268                         flex_array_free(percpu->scribble);
2269                         percpu->scribble = scribble;
2270                 } else {
2271                         err = -ENOMEM;
2272                         break;
2273                 }
2274         }
2275         put_online_cpus();
2276         mddev_resume(conf->mddev);
2277         if (!err) {
2278                 conf->scribble_disks = new_disks;
2279                 conf->scribble_sectors = new_sectors;
2280         }
2281         return err;
2282 }
2283
2284 static int resize_stripes(struct r5conf *conf, int newsize)
2285 {
2286         /* Make all the stripes able to hold 'newsize' devices.
2287          * New slots in each stripe get 'page' set to a new page.
2288          *
2289          * This happens in stages:
2290          * 1/ create a new kmem_cache and allocate the required number of
2291          *    stripe_heads.
2292          * 2/ gather all the old stripe_heads and transfer the pages across
2293          *    to the new stripe_heads.  This will have the side effect of
2294          *    freezing the array as once all stripe_heads have been collected,
2295          *    no IO will be possible.  Old stripe heads are freed once their
2296          *    pages have been transferred over, and the old kmem_cache is
2297          *    freed when all stripes are done.
2298          * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
2299          *    we simple return a failre status - no need to clean anything up.
2300          * 4/ allocate new pages for the new slots in the new stripe_heads.
2301          *    If this fails, we don't bother trying the shrink the
2302          *    stripe_heads down again, we just leave them as they are.
2303          *    As each stripe_head is processed the new one is released into
2304          *    active service.
2305          *
2306          * Once step2 is started, we cannot afford to wait for a write,
2307          * so we use GFP_NOIO allocations.
2308          */
2309         struct stripe_head *osh, *nsh;
2310         LIST_HEAD(newstripes);
2311         struct disk_info *ndisks;
2312         int err;
2313         struct kmem_cache *sc;
2314         int i;
2315         int hash, cnt;
2316
2317         if (newsize <= conf->pool_size)
2318                 return 0; /* never bother to shrink */
2319
2320         err = md_allow_write(conf->mddev);
2321         if (err)
2322                 return err;
2323
2324         /* Step 1 */
2325         sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
2326                                sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
2327                                0, 0, NULL);
2328         if (!sc)
2329                 return -ENOMEM;
2330
2331         /* Need to ensure auto-resizing doesn't interfere */
2332         mutex_lock(&conf->cache_size_mutex);
2333
2334         for (i = conf->max_nr_stripes; i; i--) {
2335                 nsh = alloc_stripe(sc, GFP_KERNEL, newsize);
2336                 if (!nsh)
2337                         break;
2338
2339                 nsh->raid_conf = conf;
2340                 list_add(&nsh->lru, &newstripes);
2341         }
2342         if (i) {
2343                 /* didn't get enough, give up */
2344                 while (!list_empty(&newstripes)) {
2345                         nsh = list_entry(newstripes.next, struct stripe_head, lru);
2346                         list_del(&nsh->lru);
2347                         kmem_cache_free(sc, nsh);
2348                 }
2349                 kmem_cache_destroy(sc);
2350                 mutex_unlock(&conf->cache_size_mutex);
2351                 return -ENOMEM;
2352         }
2353         /* Step 2 - Must use GFP_NOIO now.
2354          * OK, we have enough stripes, start collecting inactive
2355          * stripes and copying them over
2356          */
2357         hash = 0;
2358         cnt = 0;
2359         list_for_each_entry(nsh, &newstripes, lru) {
2360                 lock_device_hash_lock(conf, hash);
2361                 wait_event_cmd(conf->wait_for_stripe,
2362                                     !list_empty(conf->inactive_list + hash),
2363                                     unlock_device_hash_lock(conf, hash),
2364                                     lock_device_hash_lock(conf, hash));
2365                 osh = get_free_stripe(conf, hash);
2366                 unlock_device_hash_lock(conf, hash);
2367
2368                 for(i=0; i<conf->pool_size; i++) {
2369                         nsh->dev[i].page = osh->dev[i].page;
2370                         nsh->dev[i].orig_page = osh->dev[i].page;
2371                 }
2372                 nsh->hash_lock_index = hash;
2373                 kmem_cache_free(conf->slab_cache, osh);
2374                 cnt++;
2375                 if (cnt >= conf->max_nr_stripes / NR_STRIPE_HASH_LOCKS +
2376                     !!((conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS) > hash)) {
2377                         hash++;
2378                         cnt = 0;
2379                 }
2380         }
2381         kmem_cache_destroy(conf->slab_cache);
2382
2383         /* Step 3.
2384          * At this point, we are holding all the stripes so the array
2385          * is completely stalled, so now is a good time to resize
2386          * conf->disks and the scribble region
2387          */
2388         ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
2389         if (ndisks) {
2390                 for (i = 0; i < conf->pool_size; i++)
2391                         ndisks[i] = conf->disks[i];
2392
2393                 for (i = conf->pool_size; i < newsize; i++) {
2394                         ndisks[i].extra_page = alloc_page(GFP_NOIO);
2395                         if (!ndisks[i].extra_page)
2396                                 err = -ENOMEM;
2397                 }
2398
2399                 if (err) {
2400                         for (i = conf->pool_size; i < newsize; i++)
2401                                 if (ndisks[i].extra_page)
2402                                         put_page(ndisks[i].extra_page);
2403                         kfree(ndisks);
2404                 } else {
2405                         kfree(conf->disks);
2406                         conf->disks = ndisks;
2407                 }
2408         } else
2409                 err = -ENOMEM;
2410
2411         mutex_unlock(&conf->cache_size_mutex);
2412         /* Step 4, return new stripes to service */
2413         while(!list_empty(&newstripes)) {
2414                 nsh = list_entry(newstripes.next, struct stripe_head, lru);
2415                 list_del_init(&nsh->lru);
2416
2417                 for (i=conf->raid_disks; i < newsize; i++)
2418                         if (nsh->dev[i].page == NULL) {
2419                                 struct page *p = alloc_page(GFP_NOIO);
2420                                 nsh->dev[i].page = p;
2421                                 nsh->dev[i].orig_page = p;
2422                                 if (!p)
2423                                         err = -ENOMEM;
2424                         }
2425                 raid5_release_stripe(nsh);
2426         }
2427         /* critical section pass, GFP_NOIO no longer needed */
2428
2429         conf->slab_cache = sc;
2430         conf->active_name = 1-conf->active_name;
2431         if (!err)
2432                 conf->pool_size = newsize;
2433         return err;
2434 }
2435
2436 static int drop_one_stripe(struct r5conf *conf)
2437 {
2438         struct stripe_head *sh;
2439         int hash = (conf->max_nr_stripes - 1) & STRIPE_HASH_LOCKS_MASK;
2440
2441         spin_lock_irq(conf->hash_locks + hash);
2442         sh = get_free_stripe(conf, hash);
2443         spin_unlock_irq(conf->hash_locks + hash);
2444         if (!sh)
2445                 return 0;
2446         BUG_ON(atomic_read(&sh->count));
2447         shrink_buffers(sh);
2448         kmem_cache_free(conf->slab_cache, sh);
2449         atomic_dec(&conf->active_stripes);
2450         conf->max_nr_stripes--;
2451         return 1;
2452 }
2453
2454 static void shrink_stripes(struct r5conf *conf)
2455 {
2456         while (conf->max_nr_stripes &&
2457                drop_one_stripe(conf))
2458                 ;
2459
2460         kmem_cache_destroy(conf->slab_cache);
2461         conf->slab_cache = NULL;
2462 }
2463
2464 static void raid5_end_read_request(struct bio * bi)
2465 {
2466         struct stripe_head *sh = bi->bi_private;
2467         struct r5conf *conf = sh->raid_conf;
2468         int disks = sh->disks, i;
2469         char b[BDEVNAME_SIZE];
2470         struct md_rdev *rdev = NULL;
2471         sector_t s;
2472
2473         for (i=0 ; i<disks; i++)
2474                 if (bi == &sh->dev[i].req)
2475                         break;
2476
2477         pr_debug("end_read_request %llu/%d, count: %d, error %d.\n",
2478                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
2479                 bi->bi_error);
2480         if (i == disks) {
2481                 bio_reset(bi);
2482                 BUG();
2483                 return;
2484         }
2485         if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
2486                 /* If replacement finished while this request was outstanding,
2487                  * 'replacement' might be NULL already.
2488                  * In that case it moved down to 'rdev'.
2489                  * rdev is not removed until all requests are finished.
2490                  */
2491                 rdev = conf->disks[i].replacement;
2492         if (!rdev)
2493                 rdev = conf->disks[i].rdev;
2494
2495         if (use_new_offset(conf, sh))
2496                 s = sh->sector + rdev->new_data_offset;
2497         else
2498                 s = sh->sector + rdev->data_offset;
2499         if (!bi->bi_error) {
2500                 set_bit(R5_UPTODATE, &sh->dev[i].flags);
2501                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2502                         /* Note that this cannot happen on a
2503                          * replacement device.  We just fail those on
2504                          * any error
2505                          */
2506                         pr_info_ratelimited(
2507                                 "md/raid:%s: read error corrected (%lu sectors at %llu on %s)\n",
2508                                 mdname(conf->mddev), STRIPE_SECTORS,
2509                                 (unsigned long long)s,
2510                                 bdevname(rdev->bdev, b));
2511                         atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
2512                         clear_bit(R5_ReadError, &sh->dev[i].flags);
2513                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
2514                 } else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2515                         clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2516
2517                 if (test_bit(R5_InJournal, &sh->dev[i].flags))
2518                         /*
2519                          * end read for a page in journal, this
2520                          * must be preparing for prexor in rmw
2521                          */
2522                         set_bit(R5_OrigPageUPTDODATE, &sh->dev[i].flags);
2523
2524                 if (atomic_read(&rdev->read_errors))
2525                         atomic_set(&rdev->read_errors, 0);
2526         } else {
2527                 const char *bdn = bdevname(rdev->bdev, b);
2528                 int retry = 0;
2529                 int set_bad = 0;
2530
2531                 clear_bit(R5_UPTODATE, &sh->dev[i].flags);
2532                 atomic_inc(&rdev->read_errors);
2533                 if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
2534                         pr_warn_ratelimited(
2535                                 "md/raid:%s: read error on replacement device (sector %llu on %s).\n",
2536                                 mdname(conf->mddev),
2537                                 (unsigned long long)s,
2538                                 bdn);
2539                 else if (conf->mddev->degraded >= conf->max_degraded) {
2540                         set_bad = 1;
2541                         pr_warn_ratelimited(
2542                                 "md/raid:%s: read error not correctable (sector %llu on %s).\n",
2543                                 mdname(conf->mddev),
2544                                 (unsigned long long)s,
2545                                 bdn);
2546                 } else if (test_bit(R5_ReWrite, &sh->dev[i].flags)) {
2547                         /* Oh, no!!! */
2548                         set_bad = 1;
2549                         pr_warn_ratelimited(
2550                                 "md/raid:%s: read error NOT corrected!! (sector %llu on %s).\n",
2551                                 mdname(conf->mddev),
2552                                 (unsigned long long)s,
2553                                 bdn);
2554                 } else if (atomic_read(&rdev->read_errors)
2555                          > conf->max_nr_stripes)
2556                         pr_warn("md/raid:%s: Too many read errors, failing device %s.\n",
2557                                mdname(conf->mddev), bdn);
2558                 else
2559                         retry = 1;
2560                 if (set_bad && test_bit(In_sync, &rdev->flags)
2561                     && !test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2562                         retry = 1;
2563                 if (retry)
2564                         if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags)) {
2565                                 set_bit(R5_ReadError, &sh->dev[i].flags);
2566                                 clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2567                         } else
2568                                 set_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2569                 else {
2570                         clear_bit(R5_ReadError, &sh->dev[i].flags);
2571                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
2572                         if (!(set_bad
2573                               && test_bit(In_sync, &rdev->flags)
2574                               && rdev_set_badblocks(
2575                                       rdev, sh->sector, STRIPE_SECTORS, 0)))
2576                                 md_error(conf->mddev, rdev);
2577                 }
2578         }
2579         rdev_dec_pending(rdev, conf->mddev);
2580         bio_reset(bi);
2581         clear_bit(R5_LOCKED, &sh->dev[i].flags);
2582         set_bit(STRIPE_HANDLE, &sh->state);
2583         raid5_release_stripe(sh);
2584 }
2585
2586 static void raid5_end_write_request(struct bio *bi)
2587 {
2588         struct stripe_head *sh = bi->bi_private;
2589         struct r5conf *conf = sh->raid_conf;
2590         int disks = sh->disks, i;
2591         struct md_rdev *uninitialized_var(rdev);
2592         sector_t first_bad;
2593         int bad_sectors;
2594         int replacement = 0;
2595
2596         for (i = 0 ; i < disks; i++) {
2597                 if (bi == &sh->dev[i].req) {
2598                         rdev = conf->disks[i].rdev;
2599                         break;
2600                 }
2601                 if (bi == &sh->dev[i].rreq) {
2602                         rdev = conf->disks[i].replacement;
2603                         if (rdev)
2604                                 replacement = 1;
2605                         else
2606                                 /* rdev was removed and 'replacement'
2607                                  * replaced it.  rdev is not removed
2608                                  * until all requests are finished.
2609                                  */
2610                                 rdev = conf->disks[i].rdev;
2611                         break;
2612                 }
2613         }
2614         pr_debug("end_write_request %llu/%d, count %d, error: %d.\n",
2615                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
2616                 bi->bi_error);
2617         if (i == disks) {
2618                 bio_reset(bi);
2619                 BUG();
2620                 return;
2621         }
2622
2623         if (replacement) {
2624                 if (bi->bi_error)
2625                         md_error(conf->mddev, rdev);
2626                 else if (is_badblock(rdev, sh->sector,
2627                                      STRIPE_SECTORS,
2628                                      &first_bad, &bad_sectors))
2629                         set_bit(R5_MadeGoodRepl, &sh->dev[i].flags);
2630         } else {
2631                 if (bi->bi_error) {
2632                         set_bit(STRIPE_DEGRADED, &sh->state);
2633                         set_bit(WriteErrorSeen, &rdev->flags);
2634                         set_bit(R5_WriteError, &sh->dev[i].flags);
2635                         if (!test_and_set_bit(WantReplacement, &rdev->flags))
2636                                 set_bit(MD_RECOVERY_NEEDED,
2637                                         &rdev->mddev->recovery);
2638                 } else if (is_badblock(rdev, sh->sector,
2639                                        STRIPE_SECTORS,
2640                                        &first_bad, &bad_sectors)) {
2641                         set_bit(R5_MadeGood, &sh->dev[i].flags);
2642                         if (test_bit(R5_ReadError, &sh->dev[i].flags))
2643                                 /* That was a successful write so make
2644                                  * sure it looks like we already did
2645                                  * a re-write.
2646                                  */
2647                                 set_bit(R5_ReWrite, &sh->dev[i].flags);
2648                 }
2649         }
2650         rdev_dec_pending(rdev, conf->mddev);
2651
2652         if (sh->batch_head && bi->bi_error && !replacement)
2653                 set_bit(STRIPE_BATCH_ERR, &sh->batch_head->state);
2654
2655         bio_reset(bi);
2656         if (!test_and_clear_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags))
2657                 clear_bit(R5_LOCKED, &sh->dev[i].flags);
2658         set_bit(STRIPE_HANDLE, &sh->state);
2659         raid5_release_stripe(sh);
2660
2661         if (sh->batch_head && sh != sh->batch_head)
2662                 raid5_release_stripe(sh->batch_head);
2663 }
2664
2665 static void raid5_build_block(struct stripe_head *sh, int i, int previous)
2666 {
2667         struct r5dev *dev = &sh->dev[i];
2668
2669         dev->flags = 0;
2670         dev->sector = raid5_compute_blocknr(sh, i, previous);
2671 }
2672
2673 static void raid5_error(struct mddev *mddev, struct md_rdev *rdev)
2674 {
2675         char b[BDEVNAME_SIZE];
2676         struct r5conf *conf = mddev->private;
2677         unsigned long flags;
2678         pr_debug("raid456: error called\n");
2679
2680         spin_lock_irqsave(&conf->device_lock, flags);
2681         clear_bit(In_sync, &rdev->flags);
2682         mddev->degraded = raid5_calc_degraded(conf);
2683         spin_unlock_irqrestore(&conf->device_lock, flags);
2684         set_bit(MD_RECOVERY_INTR, &mddev->recovery);
2685
2686         set_bit(Blocked, &rdev->flags);
2687         set_bit(Faulty, &rdev->flags);
2688         set_mask_bits(&mddev->sb_flags, 0,
2689                       BIT(MD_SB_CHANGE_DEVS) | BIT(MD_SB_CHANGE_PENDING));
2690         pr_crit("md/raid:%s: Disk failure on %s, disabling device.\n"
2691                 "md/raid:%s: Operation continuing on %d devices.\n",
2692                 mdname(mddev),
2693                 bdevname(rdev->bdev, b),
2694                 mdname(mddev),
2695                 conf->raid_disks - mddev->degraded);
2696         r5c_update_on_rdev_error(mddev);
2697 }
2698
2699 /*
2700  * Input: a 'big' sector number,
2701  * Output: index of the data and parity disk, and the sector # in them.
2702  */
2703 sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
2704                               int previous, int *dd_idx,
2705                               struct stripe_head *sh)
2706 {
2707         sector_t stripe, stripe2;
2708         sector_t chunk_number;
2709         unsigned int chunk_offset;
2710         int pd_idx, qd_idx;
2711         int ddf_layout = 0;
2712         sector_t new_sector;
2713         int algorithm = previous ? conf->prev_algo
2714                                  : conf->algorithm;
2715         int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2716                                          : conf->chunk_sectors;
2717         int raid_disks = previous ? conf->previous_raid_disks
2718                                   : conf->raid_disks;
2719         int data_disks = raid_disks - conf->max_degraded;
2720
2721         /* First compute the information on this sector */
2722
2723         /*
2724          * Compute the chunk number and the sector offset inside the chunk
2725          */
2726         chunk_offset = sector_div(r_sector, sectors_per_chunk);
2727         chunk_number = r_sector;
2728
2729         /*
2730          * Compute the stripe number
2731          */
2732         stripe = chunk_number;
2733         *dd_idx = sector_div(stripe, data_disks);
2734         stripe2 = stripe;
2735         /*
2736          * Select the parity disk based on the user selected algorithm.
2737          */
2738         pd_idx = qd_idx = -1;
2739         switch(conf->level) {
2740         case 4:
2741                 pd_idx = data_disks;
2742                 break;
2743         case 5:
2744                 switch (algorithm) {
2745                 case ALGORITHM_LEFT_ASYMMETRIC:
2746                         pd_idx = data_disks - sector_div(stripe2, raid_disks);
2747                         if (*dd_idx >= pd_idx)
2748                                 (*dd_idx)++;
2749                         break;
2750                 case ALGORITHM_RIGHT_ASYMMETRIC:
2751                         pd_idx = sector_div(stripe2, raid_disks);
2752                         if (*dd_idx >= pd_idx)
2753                                 (*dd_idx)++;
2754                         break;
2755                 case ALGORITHM_LEFT_SYMMETRIC:
2756                         pd_idx = data_disks - sector_div(stripe2, raid_disks);
2757                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2758                         break;
2759                 case ALGORITHM_RIGHT_SYMMETRIC:
2760                         pd_idx = sector_div(stripe2, raid_disks);
2761                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2762                         break;
2763                 case ALGORITHM_PARITY_0:
2764                         pd_idx = 0;
2765                         (*dd_idx)++;
2766                         break;
2767                 case ALGORITHM_PARITY_N:
2768                         pd_idx = data_disks;
2769                         break;
2770                 default:
2771                         BUG();
2772                 }
2773                 break;
2774         case 6:
2775
2776                 switch (algorithm) {
2777                 case ALGORITHM_LEFT_ASYMMETRIC:
2778                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2779                         qd_idx = pd_idx + 1;
2780                         if (pd_idx == raid_disks-1) {
2781                                 (*dd_idx)++;    /* Q D D D P */
2782                                 qd_idx = 0;
2783                         } else if (*dd_idx >= pd_idx)
2784                                 (*dd_idx) += 2; /* D D P Q D */
2785                         break;
2786                 case ALGORITHM_RIGHT_ASYMMETRIC:
2787                         pd_idx = sector_div(stripe2, raid_disks);
2788                         qd_idx = pd_idx + 1;
2789                         if (pd_idx == raid_disks-1) {
2790                                 (*dd_idx)++;    /* Q D D D P */
2791                                 qd_idx = 0;
2792                         } else if (*dd_idx >= pd_idx)
2793                                 (*dd_idx) += 2; /* D D P Q D */
2794                         break;
2795                 case ALGORITHM_LEFT_SYMMETRIC:
2796                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2797                         qd_idx = (pd_idx + 1) % raid_disks;
2798                         *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2799                         break;
2800                 case ALGORITHM_RIGHT_SYMMETRIC:
2801                         pd_idx = sector_div(stripe2, raid_disks);
2802                         qd_idx = (pd_idx + 1) % raid_disks;
2803                         *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2804                         break;
2805
2806                 case ALGORITHM_PARITY_0:
2807                         pd_idx = 0;
2808                         qd_idx = 1;
2809                         (*dd_idx) += 2;
2810                         break;
2811                 case ALGORITHM_PARITY_N:
2812                         pd_idx = data_disks;
2813                         qd_idx = data_disks + 1;
2814                         break;
2815
2816                 case ALGORITHM_ROTATING_ZERO_RESTART:
2817                         /* Exactly the same as RIGHT_ASYMMETRIC, but or
2818                          * of blocks for computing Q is different.
2819                          */
2820                         pd_idx = sector_div(stripe2, raid_disks);
2821                         qd_idx = pd_idx + 1;
2822                         if (pd_idx == raid_disks-1) {
2823                                 (*dd_idx)++;    /* Q D D D P */
2824                                 qd_idx = 0;
2825                         } else if (*dd_idx >= pd_idx)
2826                                 (*dd_idx) += 2; /* D D P Q D */
2827                         ddf_layout = 1;
2828                         break;
2829
2830                 case ALGORITHM_ROTATING_N_RESTART:
2831                         /* Same a left_asymmetric, by first stripe is
2832                          * D D D P Q  rather than
2833                          * Q D D D P
2834                          */
2835                         stripe2 += 1;
2836                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2837                         qd_idx = pd_idx + 1;
2838                         if (pd_idx == raid_disks-1) {
2839                                 (*dd_idx)++;    /* Q D D D P */
2840                                 qd_idx = 0;
2841                         } else if (*dd_idx >= pd_idx)
2842                                 (*dd_idx) += 2; /* D D P Q D */
2843                         ddf_layout = 1;
2844                         break;
2845
2846                 case ALGORITHM_ROTATING_N_CONTINUE:
2847                         /* Same as left_symmetric but Q is before P */
2848                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2849                         qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
2850                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2851                         ddf_layout = 1;
2852                         break;
2853
2854                 case ALGORITHM_LEFT_ASYMMETRIC_6:
2855                         /* RAID5 left_asymmetric, with Q on last device */
2856                         pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2857                         if (*dd_idx >= pd_idx)
2858                                 (*dd_idx)++;
2859                         qd_idx = raid_disks - 1;
2860                         break;
2861
2862                 case ALGORITHM_RIGHT_ASYMMETRIC_6:
2863                         pd_idx = sector_div(stripe2, raid_disks-1);
2864                         if (*dd_idx >= pd_idx)
2865                                 (*dd_idx)++;
2866                         qd_idx = raid_disks - 1;
2867                         break;
2868
2869                 case ALGORITHM_LEFT_SYMMETRIC_6:
2870                         pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2871                         *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2872                         qd_idx = raid_disks - 1;
2873                         break;
2874
2875                 case ALGORITHM_RIGHT_SYMMETRIC_6:
2876                         pd_idx = sector_div(stripe2, raid_disks-1);
2877                         *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2878                         qd_idx = raid_disks - 1;
2879                         break;
2880
2881                 case ALGORITHM_PARITY_0_6:
2882                         pd_idx = 0;
2883                         (*dd_idx)++;
2884                         qd_idx = raid_disks - 1;
2885                         break;
2886
2887                 default:
2888                         BUG();
2889                 }
2890                 break;
2891         }
2892
2893         if (sh) {
2894                 sh->pd_idx = pd_idx;
2895                 sh->qd_idx = qd_idx;
2896                 sh->ddf_layout = ddf_layout;
2897         }
2898         /*
2899          * Finally, compute the new sector number
2900          */
2901         new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
2902         return new_sector;
2903 }
2904
2905 sector_t raid5_compute_blocknr(struct stripe_head *sh, int i, int previous)
2906 {
2907         struct r5conf *conf = sh->raid_conf;
2908         int raid_disks = sh->disks;
2909         int data_disks = raid_disks - conf->max_degraded;
2910         sector_t new_sector = sh->sector, check;
2911         int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2912                                          : conf->chunk_sectors;
2913         int algorithm = previous ? conf->prev_algo
2914                                  : conf->algorithm;
2915         sector_t stripe;
2916         int chunk_offset;
2917         sector_t chunk_number;
2918         int dummy1, dd_idx = i;
2919         sector_t r_sector;
2920         struct stripe_head sh2;
2921
2922         chunk_offset = sector_div(new_sector, sectors_per_chunk);
2923         stripe = new_sector;
2924
2925         if (i == sh->pd_idx)
2926                 return 0;
2927         switch(conf->level) {
2928         case 4: break;
2929         case 5:
2930                 switch (algorithm) {
2931                 case ALGORITHM_LEFT_ASYMMETRIC:
2932                 case ALGORITHM_RIGHT_ASYMMETRIC:
2933                         if (i > sh->pd_idx)
2934                                 i--;
2935                         break;
2936                 case ALGORITHM_LEFT_SYMMETRIC:
2937                 case ALGORITHM_RIGHT_SYMMETRIC:
2938                         if (i < sh->pd_idx)
2939                                 i += raid_disks;
2940                         i -= (sh->pd_idx + 1);
2941                         break;
2942                 case ALGORITHM_PARITY_0:
2943                         i -= 1;
2944                         break;
2945                 case ALGORITHM_PARITY_N:
2946                         break;
2947                 default:
2948                         BUG();
2949                 }
2950                 break;
2951         case 6:
2952                 if (i == sh->qd_idx)
2953                         return 0; /* It is the Q disk */
2954                 switch (algorithm) {
2955                 case ALGORITHM_LEFT_ASYMMETRIC:
2956                 case ALGORITHM_RIGHT_ASYMMETRIC:
2957                 case ALGORITHM_ROTATING_ZERO_RESTART:
2958                 case ALGORITHM_ROTATING_N_RESTART:
2959                         if (sh->pd_idx == raid_disks-1)
2960                                 i--;    /* Q D D D P */
2961                         else if (i > sh->pd_idx)
2962                                 i -= 2; /* D D P Q D */
2963                         break;
2964                 case ALGORITHM_LEFT_SYMMETRIC:
2965                 case ALGORITHM_RIGHT_SYMMETRIC:
2966                         if (sh->pd_idx == raid_disks-1)
2967                                 i--; /* Q D D D P */
2968                         else {
2969                                 /* D D P Q D */
2970                                 if (i < sh->pd_idx)
2971                                         i += raid_disks;
2972                                 i -= (sh->pd_idx + 2);
2973                         }
2974                         break;
2975                 case ALGORITHM_PARITY_0:
2976                         i -= 2;
2977                         break;
2978                 case ALGORITHM_PARITY_N:
2979                         break;
2980                 case ALGORITHM_ROTATING_N_CONTINUE:
2981                         /* Like left_symmetric, but P is before Q */
2982                         if (sh->pd_idx == 0)
2983                                 i--;    /* P D D D Q */
2984                         else {
2985                                 /* D D Q P D */
2986                                 if (i < sh->pd_idx)
2987                                         i += raid_disks;
2988                                 i -= (sh->pd_idx + 1);
2989                         }
2990                         break;
2991                 case ALGORITHM_LEFT_ASYMMETRIC_6:
2992                 case ALGORITHM_RIGHT_ASYMMETRIC_6:
2993                         if (i > sh->pd_idx)
2994                                 i--;
2995                         break;
2996                 case ALGORITHM_LEFT_SYMMETRIC_6:
2997                 case ALGORITHM_RIGHT_SYMMETRIC_6:
2998                         if (i < sh->pd_idx)
2999                                 i += data_disks + 1;
3000                         i -= (sh->pd_idx + 1);
3001                         break;
3002                 case ALGORITHM_PARITY_0_6:
3003                         i -= 1;
3004                         break;
3005                 default:
3006                         BUG();
3007                 }
3008                 break;
3009         }
3010
3011         chunk_number = stripe * data_disks + i;
3012         r_sector = chunk_number * sectors_per_chunk + chunk_offset;
3013
3014         check = raid5_compute_sector(conf, r_sector,
3015                                      previous, &dummy1, &sh2);
3016         if (check != sh->sector || dummy1 != dd_idx || sh2.pd_idx != sh->pd_idx
3017                 || sh2.qd_idx != sh->qd_idx) {
3018                 pr_warn("md/raid:%s: compute_blocknr: map not correct\n",
3019                         mdname(conf->mddev));
3020                 return 0;
3021         }
3022         return r_sector;
3023 }
3024
3025 /*
3026  * There are cases where we want handle_stripe_dirtying() and
3027  * schedule_reconstruction() to delay towrite to some dev of a stripe.
3028  *
3029  * This function checks whether we want to delay the towrite. Specifically,
3030  * we delay the towrite when:
3031  *
3032  *   1. degraded stripe has a non-overwrite to the missing dev, AND this
3033  *      stripe has data in journal (for other devices).
3034  *
3035  *      In this case, when reading data for the non-overwrite dev, it is
3036  *      necessary to handle complex rmw of write back cache (prexor with
3037  *      orig_page, and xor with page). To keep read path simple, we would
3038  *      like to flush data in journal to RAID disks first, so complex rmw
3039  *      is handled in the write patch (handle_stripe_dirtying).
3040  *
3041  *   2. when journal space is critical (R5C_LOG_CRITICAL=1)
3042  *
3043  *      It is important to be able to flush all stripes in raid5-cache.
3044  *      Therefore, we need reserve some space on the journal device for
3045  *      these flushes. If flush operation includes pending writes to the
3046  *      stripe, we need to reserve (conf->raid_disk + 1) pages per stripe
3047  *      for the flush out. If we exclude these pending writes from flush
3048  *      operation, we only need (conf->max_degraded + 1) pages per stripe.
3049  *      Therefore, excluding pending writes in these cases enables more
3050  *      efficient use of the journal device.
3051  *
3052  *      Note: To make sure the stripe makes progress, we only delay
3053  *      towrite for stripes with data already in journal (injournal > 0).
3054  *      When LOG_CRITICAL, stripes with injournal == 0 will be sent to
3055  *      no_space_stripes list.
3056  *
3057  */
3058 static inline bool delay_towrite(struct r5conf *conf,
3059                                  struct r5dev *dev,
3060                                  struct stripe_head_state *s)
3061 {
3062         /* case 1 above */
3063         if (!test_bit(R5_OVERWRITE, &dev->flags) &&
3064             !test_bit(R5_Insync, &dev->flags) && s->injournal)
3065                 return true;
3066         /* case 2 above */
3067         if (test_bit(R5C_LOG_CRITICAL, &conf->cache_state) &&
3068             s->injournal > 0)
3069                 return true;
3070         return false;
3071 }
3072
3073 static void
3074 schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
3075                          int rcw, int expand)
3076 {
3077         int i, pd_idx = sh->pd_idx, qd_idx = sh->qd_idx, disks = sh->disks;
3078         struct r5conf *conf = sh->raid_conf;
3079         int level = conf->level;
3080
3081         if (rcw) {
3082                 /*
3083                  * In some cases, handle_stripe_dirtying initially decided to
3084                  * run rmw and allocates extra page for prexor. However, rcw is
3085                  * cheaper later on. We need to free the extra page now,
3086                  * because we won't be able to do that in ops_complete_prexor().
3087                  */
3088                 r5c_release_extra_page(sh);
3089
3090                 for (i = disks; i--; ) {
3091                         struct r5dev *dev = &sh->dev[i];
3092
3093                         if (dev->towrite && !delay_towrite(conf, dev, s)) {
3094                                 set_bit(R5_LOCKED, &dev->flags);
3095                                 set_bit(R5_Wantdrain, &dev->flags);
3096                                 if (!expand)
3097                                         clear_bit(R5_UPTODATE, &dev->flags);
3098                                 s->locked++;
3099                         } else if (test_bit(R5_InJournal, &dev->flags)) {
3100                                 set_bit(R5_LOCKED, &dev->flags);
3101                                 s->locked++;
3102                         }
3103                 }
3104                 /* if we are not expanding this is a proper write request, and
3105                  * there will be bios with new data to be drained into the
3106                  * stripe cache
3107                  */
3108                 if (!expand) {
3109                         if (!s->locked)
3110                                 /* False alarm, nothing to do */
3111                                 return;
3112                         sh->reconstruct_state = reconstruct_state_drain_run;
3113                         set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
3114                 } else
3115                         sh->reconstruct_state = reconstruct_state_run;
3116
3117                 set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
3118
3119                 if (s->locked + conf->max_degraded == disks)
3120                         if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
3121                                 atomic_inc(&conf->pending_full_writes);
3122         } else {
3123                 BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
3124                         test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
3125                 BUG_ON(level == 6 &&
3126                         (!(test_bit(R5_UPTODATE, &sh->dev[qd_idx].flags) ||
3127                            test_bit(R5_Wantcompute, &sh->dev[qd_idx].flags))));
3128
3129                 for (i = disks; i--; ) {
3130                         struct r5dev *dev = &sh->dev[i];
3131                         if (i == pd_idx || i == qd_idx)
3132                                 continue;
3133
3134                         if (dev->towrite &&
3135                             (test_bit(R5_UPTODATE, &dev->flags) ||
3136                              test_bit(R5_Wantcompute, &dev->flags))) {
3137                                 set_bit(R5_Wantdrain, &dev->flags);
3138                                 set_bit(R5_LOCKED, &dev->flags);
3139                                 clear_bit(R5_UPTODATE, &dev->flags);
3140                                 s->locked++;
3141                         } else if (test_bit(R5_InJournal, &dev->flags)) {
3142                                 set_bit(R5_LOCKED, &dev->flags);
3143                                 s->locked++;
3144                         }
3145                 }
3146                 if (!s->locked)
3147                         /* False alarm - nothing to do */
3148                         return;
3149                 sh->reconstruct_state = reconstruct_state_prexor_drain_run;
3150                 set_bit(STRIPE_OP_PREXOR, &s->ops_request);
3151                 set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
3152                 set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
3153         }
3154
3155         /* keep the parity disk(s) locked while asynchronous operations
3156          * are in flight
3157          */
3158         set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
3159         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
3160         s->locked++;
3161
3162         if (level == 6) {
3163                 int qd_idx = sh->qd_idx;
3164                 struct r5dev *dev = &sh->dev[qd_idx];
3165
3166                 set_bit(R5_LOCKED, &dev->flags);
3167                 clear_bit(R5_UPTODATE, &dev->flags);
3168                 s->locked++;
3169         }
3170
3171         if (raid5_has_ppl(sh->raid_conf) &&
3172             test_bit(STRIPE_OP_BIODRAIN, &s->ops_request) &&
3173             !test_bit(STRIPE_FULL_WRITE, &sh->state) &&
3174             test_bit(R5_Insync, &sh->dev[pd_idx].flags))
3175                 set_bit(STRIPE_OP_PARTIAL_PARITY, &s->ops_request);
3176
3177         pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
3178                 __func__, (unsigned long long)sh->sector,
3179                 s->locked, s->ops_request);
3180 }
3181
3182 /*
3183  * Each stripe/dev can have one or more bion attached.
3184  * toread/towrite point to the first in a chain.
3185  * The bi_next chain must be in order.
3186  */
3187 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx,
3188                           int forwrite, int previous)
3189 {
3190         struct bio **bip;
3191         struct r5conf *conf = sh->raid_conf;
3192         int firstwrite=0;
3193
3194         pr_debug("adding bi b#%llu to stripe s#%llu\n",
3195                 (unsigned long long)bi->bi_iter.bi_sector,
3196                 (unsigned long long)sh->sector);
3197
3198         spin_lock_irq(&sh->stripe_lock);
3199         /* Don't allow new IO added to stripes in batch list */
3200         if (sh->batch_head)
3201                 goto overlap;
3202         if (forwrite) {
3203                 bip = &sh->dev[dd_idx].towrite;
3204                 if (*bip == NULL)
3205                         firstwrite = 1;
3206         } else
3207                 bip = &sh->dev[dd_idx].toread;
3208         while (*bip && (*bip)->bi_iter.bi_sector < bi->bi_iter.bi_sector) {
3209                 if (bio_end_sector(*bip) > bi->bi_iter.bi_sector)
3210                         goto overlap;
3211                 bip = & (*bip)->bi_next;
3212         }
3213         if (*bip && (*bip)->bi_iter.bi_sector < bio_end_sector(bi))
3214                 goto overlap;
3215
3216         if (forwrite && raid5_has_ppl(conf)) {
3217                 /*
3218                  * With PPL only writes to consecutive data chunks within a
3219                  * stripe are allowed because for a single stripe_head we can
3220                  * only have one PPL entry at a time, which describes one data
3221                  * range. Not really an overlap, but wait_for_overlap can be
3222                  * used to handle this.
3223                  */
3224                 sector_t sector;
3225                 sector_t first = 0;
3226                 sector_t last = 0;
3227                 int count = 0;
3228                 int i;
3229
3230                 for (i = 0; i < sh->disks; i++) {
3231                         if (i != sh->pd_idx &&
3232                             (i == dd_idx || sh->dev[i].towrite)) {
3233                                 sector = sh->dev[i].sector;
3234                                 if (count == 0 || sector < first)
3235                                         first = sector;
3236                                 if (sector > last)
3237                                         last = sector;
3238                                 count++;
3239                         }
3240                 }
3241
3242                 if (first + conf->chunk_sectors * (count - 1) != last)
3243                         goto overlap;
3244         }
3245
3246         if (!forwrite || previous)
3247                 clear_bit(STRIPE_BATCH_READY, &sh->state);
3248
3249         BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
3250         if (*bip)
3251                 bi->bi_next = *bip;
3252         *bip = bi;
3253         bio_inc_remaining(bi);
3254         md_write_inc(conf->mddev, bi);
3255
3256         if (forwrite) {
3257                 /* check if page is covered */
3258                 sector_t sector = sh->dev[dd_idx].sector;
3259                 for (bi=sh->dev[dd_idx].towrite;
3260                      sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
3261                              bi && bi->bi_iter.bi_sector <= sector;
3262                      bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
3263                         if (bio_end_sector(bi) >= sector)
3264                                 sector = bio_end_sector(bi);
3265                 }
3266                 if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
3267                         if (!test_and_set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags))
3268                                 sh->overwrite_disks++;
3269         }
3270
3271         pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
3272                 (unsigned long long)(*bip)->bi_iter.bi_sector,
3273                 (unsigned long long)sh->sector, dd_idx);
3274
3275         if (conf->mddev->bitmap && firstwrite) {
3276                 /* Cannot hold spinlock over bitmap_startwrite,
3277                  * but must ensure this isn't added to a batch until
3278                  * we have added to the bitmap and set bm_seq.
3279                  * So set STRIPE_BITMAP_PENDING to prevent
3280                  * batching.
3281                  * If multiple add_stripe_bio() calls race here they
3282                  * much all set STRIPE_BITMAP_PENDING.  So only the first one
3283                  * to complete "bitmap_startwrite" gets to set
3284                  * STRIPE_BIT_DELAY.  This is important as once a stripe
3285                  * is added to a batch, STRIPE_BIT_DELAY cannot be changed
3286                  * any more.
3287                  */
3288                 set_bit(STRIPE_BITMAP_PENDING, &sh->state);
3289                 spin_unlock_irq(&sh->stripe_lock);
3290                 bitmap_startwrite(conf->mddev->bitmap, sh->sector,
3291                                   STRIPE_SECTORS, 0);
3292                 spin_lock_irq(&sh->stripe_lock);
3293                 clear_bit(STRIPE_BITMAP_PENDING, &sh->state);
3294                 if (!sh->batch_head) {
3295                         sh->bm_seq = conf->seq_flush+1;
3296                         set_bit(STRIPE_BIT_DELAY, &sh->state);
3297                 }
3298         }
3299         spin_unlock_irq(&sh->stripe_lock);
3300
3301         if (stripe_can_batch(sh))
3302                 stripe_add_to_batch_list(conf, sh);
3303         return 1;
3304
3305  overlap:
3306         set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
3307         spin_unlock_irq(&sh->stripe_lock);
3308         return 0;
3309 }
3310
3311 static void end_reshape(struct r5conf *conf);
3312
3313 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
3314                             struct stripe_head *sh)
3315 {
3316         int sectors_per_chunk =
3317                 previous ? conf->prev_chunk_sectors : conf->chunk_sectors;
3318         int dd_idx;
3319         int chunk_offset = sector_div(stripe, sectors_per_chunk);
3320         int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
3321
3322         raid5_compute_sector(conf,
3323                              stripe * (disks - conf->max_degraded)
3324                              *sectors_per_chunk + chunk_offset,
3325                              previous,
3326                              &dd_idx, sh);
3327 }
3328
3329 static void
3330 handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
3331                      struct stripe_head_state *s, int disks)
3332 {
3333         int i;
3334         BUG_ON(sh->batch_head);
3335         for (i = disks; i--; ) {
3336                 struct bio *bi;
3337                 int bitmap_end = 0;
3338
3339                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
3340                         struct md_rdev *rdev;
3341                         rcu_read_lock();
3342                         rdev = rcu_dereference(conf->disks[i].rdev);
3343                         if (rdev && test_bit(In_sync, &rdev->flags) &&
3344                             !test_bit(Faulty, &rdev->flags))
3345                                 atomic_inc(&rdev->nr_pending);
3346                         else
3347                                 rdev = NULL;
3348                         rcu_read_unlock();
3349                         if (rdev) {
3350                                 if (!rdev_set_badblocks(
3351                                             rdev,
3352                                             sh->sector,
3353                                             STRIPE_SECTORS, 0))
3354                                         md_error(conf->mddev, rdev);
3355                                 rdev_dec_pending(rdev, conf->mddev);
3356                         }
3357                 }
3358                 spin_lock_irq(&sh->stripe_lock);
3359                 /* fail all writes first */
3360                 bi = sh->dev[i].towrite;
3361                 sh->dev[i].towrite = NULL;
3362                 sh->overwrite_disks = 0;
3363                 spin_unlock_irq(&sh->stripe_lock);
3364                 if (bi)
3365                         bitmap_end = 1;
3366
3367                 log_stripe_write_finished(sh);
3368
3369                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
3370                         wake_up(&conf->wait_for_overlap);
3371
3372                 while (bi && bi->bi_iter.bi_sector <
3373                         sh->dev[i].sector + STRIPE_SECTORS) {
3374                         struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
3375
3376                         bi->bi_error = -EIO;
3377                         md_write_end(conf->mddev);
3378                         bio_endio(bi);
3379                         bi = nextbi;
3380                 }
3381                 if (bitmap_end)
3382                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3383                                 STRIPE_SECTORS, 0, 0);
3384                 bitmap_end = 0;
3385                 /* and fail all 'written' */
3386                 bi = sh->dev[i].written;
3387                 sh->dev[i].written = NULL;
3388                 if (test_and_clear_bit(R5_SkipCopy, &sh->dev[i].flags)) {
3389                         WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
3390                         sh->dev[i].page = sh->dev[i].orig_page;
3391                 }
3392
3393                 if (bi) bitmap_end = 1;
3394                 while (bi && bi->bi_iter.bi_sector <
3395                        sh->dev[i].sector + STRIPE_SECTORS) {
3396                         struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
3397
3398                         bi->bi_error = -EIO;
3399                         md_write_end(conf->mddev);
3400                         bio_endio(bi);
3401                         bi = bi2;
3402                 }
3403
3404                 /* fail any reads if this device is non-operational and
3405                  * the data has not reached the cache yet.
3406                  */
3407                 if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
3408                     s->failed > conf->max_degraded &&
3409                     (!test_bit(R5_Insync, &sh->dev[i].flags) ||
3410                       test_bit(R5_ReadError, &sh->dev[i].flags))) {
3411                         spin_lock_irq(&sh->stripe_lock);
3412                         bi = sh->dev[i].toread;
3413                         sh->dev[i].toread = NULL;
3414                         spin_unlock_irq(&sh->stripe_lock);
3415                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
3416                                 wake_up(&conf->wait_for_overlap);
3417                         if (bi)
3418                                 s->to_read--;
3419                         while (bi && bi->bi_iter.bi_sector <
3420                                sh->dev[i].sector + STRIPE_SECTORS) {
3421                                 struct bio *nextbi =
3422                                         r5_next_bio(bi, sh->dev[i].sector);
3423
3424                                 bi->bi_error = -EIO;
3425                                 bio_endio(bi);
3426                                 bi = nextbi;
3427                         }
3428                 }
3429                 if (bitmap_end)
3430                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3431                                         STRIPE_SECTORS, 0, 0);
3432                 /* If we were in the middle of a write the parity block might
3433                  * still be locked - so just clear all R5_LOCKED flags
3434                  */
3435                 clear_bit(R5_LOCKED, &sh->dev[i].flags);
3436         }
3437         s->to_write = 0;
3438         s->written = 0;
3439
3440         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
3441                 if (atomic_dec_and_test(&conf->pending_full_writes))
3442                         md_wakeup_thread(conf->mddev->thread);
3443 }
3444
3445 static void
3446 handle_failed_sync(struct r5conf *conf, struct stripe_head *sh,
3447                    struct stripe_head_state *s)
3448 {
3449         int abort = 0;
3450         int i;
3451
3452         BUG_ON(sh->batch_head);
3453         clear_bit(STRIPE_SYNCING, &sh->state);
3454         if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
3455                 wake_up(&conf->wait_for_overlap);
3456         s->syncing = 0;
3457         s->replacing = 0;
3458         /* There is nothing more to do for sync/check/repair.
3459          * Don't even need to abort as that is handled elsewhere
3460          * if needed, and not always wanted e.g. if there is a known
3461          * bad block here.
3462          * For recover/replace we need to record a bad block on all
3463          * non-sync devices, or abort the recovery
3464          */
3465         if (test_bit(MD_RECOVERY_RECOVER, &conf->mddev->recovery)) {
3466                 /* During recovery devices cannot be removed, so
3467                  * locking and refcounting of rdevs is not needed
3468                  */
3469                 rcu_read_lock();
3470                 for (i = 0; i < conf->raid_disks; i++) {
3471                         struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
3472                         if (rdev
3473                             && !test_bit(Faulty, &rdev->flags)
3474                             && !test_bit(In_sync, &rdev->flags)
3475                             && !rdev_set_badblocks(rdev, sh->sector,
3476                                                    STRIPE_SECTORS, 0))
3477                                 abort = 1;
3478                         rdev = rcu_dereference(conf->disks[i].replacement);
3479                         if (rdev
3480                             && !test_bit(Faulty, &rdev->flags)
3481                             && !test_bit(In_sync, &rdev->flags)
3482                             && !rdev_set_badblocks(rdev, sh->sector,
3483                                                    STRIPE_SECTORS, 0))
3484                                 abort = 1;
3485                 }
3486                 rcu_read_unlock();
3487                 if (abort)
3488                         conf->recovery_disabled =
3489                                 conf->mddev->recovery_disabled;
3490         }
3491         md_done_sync(conf->mddev, STRIPE_SECTORS, !abort);
3492 }
3493
3494 static int want_replace(struct stripe_head *sh, int disk_idx)
3495 {
3496         struct md_rdev *rdev;
3497         int rv = 0;
3498
3499         rcu_read_lock();
3500         rdev = rcu_dereference(sh->raid_conf->disks[disk_idx].replacement);
3501         if (rdev
3502             && !test_bit(Faulty, &rdev->flags)
3503             && !test_bit(In_sync, &rdev->flags)
3504             && (rdev->recovery_offset <= sh->sector
3505                 || rdev->mddev->recovery_cp <= sh->sector))
3506                 rv = 1;
3507         rcu_read_unlock();
3508         return rv;
3509 }
3510
3511 static int need_this_block(struct stripe_head *sh, struct stripe_head_state *s,
3512                            int disk_idx, int disks)
3513 {
3514         struct r5dev *dev = &sh->dev[disk_idx];
3515         struct r5dev *fdev[2] = { &sh->dev[s->failed_num[0]],
3516                                   &sh->dev[s->failed_num[1]] };
3517         int i;
3518
3519
3520         if (test_bit(R5_LOCKED, &dev->flags) ||
3521             test_bit(R5_UPTODATE, &dev->flags))
3522                 /* No point reading this as we already have it or have
3523                  * decided to get it.
3524                  */
3525                 return 0;
3526
3527         if (dev->toread ||
3528             (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)))
3529                 /* We need this block to directly satisfy a request */
3530                 return 1;
3531
3532         if (s->syncing || s->expanding ||
3533             (s->replacing && want_replace(sh, disk_idx)))
3534                 /* When syncing, or expanding we read everything.
3535                  * When replacing, we need the replaced block.
3536                  */
3537                 return 1;
3538
3539         if ((s->failed >= 1 && fdev[0]->toread) ||
3540             (s->failed >= 2 && fdev[1]->toread))
3541                 /* If we want to read from a failed device, then
3542                  * we need to actually read every other device.
3543                  */
3544                 return 1;
3545
3546         /* Sometimes neither read-modify-write nor reconstruct-write
3547          * cycles can work.  In those cases we read every block we
3548          * can.  Then the parity-update is certain to have enough to
3549          * work with.
3550          * This can only be a problem when we need to write something,
3551          * and some device has failed.  If either of those tests
3552          * fail we need look no further.
3553          */
3554         if (!s->failed || !s->to_write)
3555                 return 0;
3556
3557         if (test_bit(R5_Insync, &dev->flags) &&
3558             !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3559                 /* Pre-reads at not permitted until after short delay
3560                  * to gather multiple requests.  However if this
3561                  * device is no Insync, the block could only be be computed
3562                  * and there is no need to delay that.
3563                  */
3564                 return 0;
3565
3566         for (i = 0; i < s->failed && i < 2; i++) {
3567                 if (fdev[i]->towrite &&
3568                     !test_bit(R5_UPTODATE, &fdev[i]->flags) &&
3569                     !test_bit(R5_OVERWRITE, &fdev[i]->flags))
3570                         /* If we have a partial write to a failed
3571                          * device, then we will need to reconstruct
3572                          * the content of that device, so all other
3573                          * devices must be read.
3574                          */
3575                         return 1;
3576         }
3577
3578         /* If we are forced to do a reconstruct-write, either because
3579          * the current RAID6 implementation only supports that, or
3580          * or because parity cannot be trusted and we are currently
3581          * recovering it, there is extra need to be careful.
3582          * If one of the devices that we would need to read, because
3583          * it is not being overwritten (and maybe not written at all)
3584          * is missing/faulty, then we need to read everything we can.
3585          */
3586         if (sh->raid_conf->level != 6 &&
3587             sh->sector < sh->raid_conf->mddev->recovery_cp)
3588                 /* reconstruct-write isn't being forced */
3589                 return 0;
3590         for (i = 0; i < s->failed && i < 2; i++) {
3591                 if (s->failed_num[i] != sh->pd_idx &&
3592                     s->failed_num[i] != sh->qd_idx &&
3593                     !test_bit(R5_UPTODATE, &fdev[i]->flags) &&
3594                     !test_bit(R5_OVERWRITE, &fdev[i]->flags))
3595                         return 1;
3596         }
3597
3598         return 0;
3599 }
3600
3601 /* fetch_block - checks the given member device to see if its data needs
3602  * to be read or computed to satisfy a request.
3603  *
3604  * Returns 1 when no more member devices need to be checked, otherwise returns
3605  * 0 to tell the loop in handle_stripe_fill to continue
3606  */
3607 static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
3608                        int disk_idx, int disks)
3609 {
3610         struct r5dev *dev = &sh->dev[disk_idx];
3611
3612         /* is the data in this block needed, and can we get it? */
3613         if (need_this_block(sh, s, disk_idx, disks)) {
3614                 /* we would like to get this block, possibly by computing it,
3615                  * otherwise read it if the backing disk is insync
3616                  */
3617                 BUG_ON(test_bit(R5_Wantcompute, &dev->flags));
3618                 BUG_ON(test_bit(R5_Wantread, &dev->flags));
3619                 BUG_ON(sh->batch_head);
3620                 if ((s->uptodate == disks - 1) &&
3621                     (s->failed && (disk_idx == s->failed_num[0] ||
3622                                    disk_idx == s->failed_num[1]))) {
3623                         /* have disk failed, and we're requested to fetch it;
3624                          * do compute it
3625                          */
3626                         pr_debug("Computing stripe %llu block %d\n",
3627                                (unsigned long long)sh->sector, disk_idx);
3628                         set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3629                         set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3630                         set_bit(R5_Wantcompute, &dev->flags);
3631                         sh->ops.target = disk_idx;
3632                         sh->ops.target2 = -1; /* no 2nd target */
3633                         s->req_compute = 1;
3634                         /* Careful: from this point on 'uptodate' is in the eye
3635                          * of raid_run_ops which services 'compute' operations
3636                          * before writes. R5_Wantcompute flags a block that will
3637                          * be R5_UPTODATE by the time it is needed for a
3638                          * subsequent operation.
3639                          */
3640                         s->uptodate++;
3641                         return 1;
3642                 } else if (s->uptodate == disks-2 && s->failed >= 2) {
3643                         /* Computing 2-failure is *very* expensive; only
3644                          * do it if failed >= 2
3645                          */
3646                         int other;
3647                         for (other = disks; other--; ) {
3648                                 if (other == disk_idx)
3649                                         continue;
3650                                 if (!test_bit(R5_UPTODATE,
3651                                       &sh->dev[other].flags))
3652                                         break;
3653                         }
3654                         BUG_ON(other < 0);
3655                         pr_debug("Computing stripe %llu blocks %d,%d\n",
3656                                (unsigned long long)sh->sector,
3657                                disk_idx, other);
3658                         set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3659                         set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3660                         set_bit(R5_Wantcompute, &sh->dev[disk_idx].flags);
3661                         set_bit(R5_Wantcompute, &sh->dev[other].flags);
3662                         sh->ops.target = disk_idx;
3663                         sh->ops.target2 = other;
3664                         s->uptodate += 2;
3665                         s->req_compute = 1;
3666                         return 1;
3667                 } else if (test_bit(R5_Insync, &dev->flags)) {
3668                         set_bit(R5_LOCKED, &dev->flags);
3669                         set_bit(R5_Wantread, &dev->flags);
3670                         s->locked++;
3671                         pr_debug("Reading block %d (sync=%d)\n",
3672                                 disk_idx, s->syncing);
3673                 }
3674         }
3675
3676         return 0;
3677 }
3678
3679 /**
3680  * handle_stripe_fill - read or compute data to satisfy pending requests.
3681  */
3682 static void handle_stripe_fill(struct stripe_head *sh,
3683                                struct stripe_head_state *s,
3684                                int disks)
3685 {
3686         int i;
3687
3688         /* look for blocks to read/compute, skip this if a compute
3689          * is already in flight, or if the stripe contents are in the
3690          * midst of changing due to a write
3691          */
3692         if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
3693             !sh->reconstruct_state) {
3694
3695                 /*
3696                  * For degraded stripe with data in journal, do not handle
3697                  * read requests yet, instead, flush the stripe to raid
3698                  * disks first, this avoids handling complex rmw of write
3699                  * back cache (prexor with orig_page, and then xor with
3700                  * page) in the read path
3701                  */
3702                 if (s->injournal && s->failed) {
3703                         if (test_bit(STRIPE_R5C_CACHING, &sh->state))
3704                                 r5c_make_stripe_write_out(sh);
3705                         goto out;
3706                 }
3707
3708                 for (i = disks; i--; )
3709                         if (fetch_block(sh, s, i, disks))
3710                                 break;
3711         }
3712 out:
3713         set_bit(STRIPE_HANDLE, &sh->state);
3714 }
3715
3716 static void break_stripe_batch_list(struct stripe_head *head_sh,
3717                                     unsigned long handle_flags);
3718 /* handle_stripe_clean_event
3719  * any written block on an uptodate or failed drive can be returned.
3720  * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
3721  * never LOCKED, so we don't need to test 'failed' directly.
3722  */
3723 static void handle_stripe_clean_event(struct r5conf *conf,
3724         struct stripe_head *sh, int disks)
3725 {
3726         int i;
3727         struct r5dev *dev;
3728         int discard_pending = 0;
3729         struct stripe_head *head_sh = sh;
3730         bool do_endio = false;
3731
3732         for (i = disks; i--; )
3733                 if (sh->dev[i].written) {
3734                         dev = &sh->dev[i];
3735                         if (!test_bit(R5_LOCKED, &dev->flags) &&
3736                             (test_bit(R5_UPTODATE, &dev->flags) ||
3737                              test_bit(R5_Discard, &dev->flags) ||
3738                              test_bit(R5_SkipCopy, &dev->flags))) {
3739                                 /* We can return any write requests */
3740                                 struct bio *wbi, *wbi2;
3741                                 pr_debug("Return write for disc %d\n", i);
3742                                 if (test_and_clear_bit(R5_Discard, &dev->flags))
3743                                         clear_bit(R5_UPTODATE, &dev->flags);
3744                                 if (test_and_clear_bit(R5_SkipCopy, &dev->flags)) {
3745                                         WARN_ON(test_bit(R5_UPTODATE, &dev->flags));
3746                                 }
3747                                 do_endio = true;
3748
3749 returnbi:
3750                                 dev->page = dev->orig_page;
3751                                 wbi = dev->written;
3752                                 dev->written = NULL;
3753                                 while (wbi && wbi->bi_iter.bi_sector <
3754                                         dev->sector + STRIPE_SECTORS) {
3755                                         wbi2 = r5_next_bio(wbi, dev->sector);
3756                                         md_write_end(conf->mddev);
3757                                         bio_endio(wbi);
3758                                         wbi = wbi2;
3759                                 }
3760                                 bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3761                                                 STRIPE_SECTORS,
3762                                          !test_bit(STRIPE_DEGRADED, &sh->state),
3763                                                 0);
3764                                 if (head_sh->batch_head) {
3765                                         sh = list_first_entry(&sh->batch_list,
3766                                                               struct stripe_head,
3767                                                               batch_list);
3768                                         if (sh != head_sh) {
3769                                                 dev = &sh->dev[i];
3770                                                 goto returnbi;
3771                                         }
3772                                 }
3773                                 sh = head_sh;
3774                                 dev = &sh->dev[i];
3775                         } else if (test_bit(R5_Discard, &dev->flags))
3776                                 discard_pending = 1;
3777                 }
3778
3779         log_stripe_write_finished(sh);
3780
3781         if (!discard_pending &&
3782             test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
3783                 int hash;
3784                 clear_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
3785                 clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
3786                 if (sh->qd_idx >= 0) {
3787                         clear_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
3788                         clear_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags);
3789                 }
3790                 /* now that discard is done we can proceed with any sync */
3791                 clear_bit(STRIPE_DISCARD, &sh->state);
3792                 /*
3793                  * SCSI discard will change some bio fields and the stripe has
3794                  * no updated data, so remove it from hash list and the stripe
3795                  * will be reinitialized
3796                  */
3797 unhash:
3798                 hash = sh->hash_lock_index;
3799                 spin_lock_irq(conf->hash_locks + hash);
3800                 remove_hash(sh);
3801                 spin_unlock_irq(conf->hash_locks + hash);
3802                 if (head_sh->batch_head) {
3803                         sh = list_first_entry(&sh->batch_list,
3804                                               struct stripe_head, batch_list);
3805                         if (sh != head_sh)
3806                                         goto unhash;
3807                 }
3808                 sh = head_sh;
3809
3810                 if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state))
3811                         set_bit(STRIPE_HANDLE, &sh->state);
3812
3813         }
3814
3815         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
3816                 if (atomic_dec_and_test(&conf->pending_full_writes))
3817                         md_wakeup_thread(conf->mddev->thread);
3818
3819         if (head_sh->batch_head && do_endio)
3820                 break_stripe_batch_list(head_sh, STRIPE_EXPAND_SYNC_FLAGS);
3821 }
3822
3823 /*
3824  * For RMW in write back cache, we need extra page in prexor to store the
3825  * old data. This page is stored in dev->orig_page.
3826  *
3827  * This function checks whether we have data for prexor. The exact logic
3828  * is:
3829  *       R5_UPTODATE && (!R5_InJournal || R5_OrigPageUPTDODATE)
3830  */
3831 static inline bool uptodate_for_rmw(struct r5dev *dev)
3832 {
3833         return (test_bit(R5_UPTODATE, &dev->flags)) &&
3834                 (!test_bit(R5_InJournal, &dev->flags) ||
3835                  test_bit(R5_OrigPageUPTDODATE, &dev->flags));
3836 }
3837
3838 static int handle_stripe_dirtying(struct r5conf *conf,
3839                                   struct stripe_head *sh,
3840                                   struct stripe_head_state *s,
3841                                   int disks)
3842 {
3843         int rmw = 0, rcw = 0, i;
3844         sector_t recovery_cp = conf->mddev->recovery_cp;
3845
3846         /* Check whether resync is now happening or should start.
3847          * If yes, then the array is dirty (after unclean shutdown or
3848          * initial creation), so parity in some stripes might be inconsistent.
3849          * In this case, we need to always do reconstruct-write, to ensure
3850          * that in case of drive failure or read-error correction, we
3851          * generate correct data from the parity.
3852          */
3853         if (conf->rmw_level == PARITY_DISABLE_RMW ||
3854             (recovery_cp < MaxSector && sh->sector >= recovery_cp &&
3855              s->failed == 0)) {
3856                 /* Calculate the real rcw later - for now make it
3857                  * look like rcw is cheaper
3858                  */
3859                 rcw = 1; rmw = 2;
3860                 pr_debug("force RCW rmw_level=%u, recovery_cp=%llu sh->sector=%llu\n",
3861                          conf->rmw_level, (unsigned long long)recovery_cp,
3862                          (unsigned long long)sh->sector);
3863         } else for (i = disks; i--; ) {
3864                 /* would I have to read this buffer for read_modify_write */
3865                 struct r5dev *dev = &sh->dev[i];
3866                 if (((dev->towrite && !delay_towrite(conf, dev, s)) ||
3867                      i == sh->pd_idx || i == sh->qd_idx ||
3868                      test_bit(R5_InJournal, &dev->flags)) &&
3869                     !test_bit(R5_LOCKED, &dev->flags) &&
3870                     !(uptodate_for_rmw(dev) ||
3871                       test_bit(R5_Wantcompute, &dev->flags))) {
3872                         if (test_bit(R5_Insync, &dev->flags))
3873                                 rmw++;
3874                         else
3875                                 rmw += 2*disks;  /* cannot read it */
3876                 }
3877                 /* Would I have to read this buffer for reconstruct_write */
3878                 if (!test_bit(R5_OVERWRITE, &dev->flags) &&
3879                     i != sh->pd_idx && i != sh->qd_idx &&
3880                     !test_bit(R5_LOCKED, &dev->flags) &&
3881                     !(test_bit(R5_UPTODATE, &dev->flags) ||
3882                       test_bit(R5_Wantcompute, &dev->flags))) {
3883                         if (test_bit(R5_Insync, &dev->flags))
3884                                 rcw++;
3885                         else
3886                                 rcw += 2*disks;
3887                 }
3888         }
3889
3890         pr_debug("for sector %llu state 0x%lx, rmw=%d rcw=%d\n",
3891                  (unsigned long long)sh->sector, sh->state, rmw, rcw);
3892         set_bit(STRIPE_HANDLE, &sh->state);
3893         if ((rmw < rcw || (rmw == rcw && conf->rmw_level == PARITY_PREFER_RMW)) && rmw > 0) {
3894                 /* prefer read-modify-write, but need to get some data */
3895                 if (conf->mddev->queue)
3896                         blk_add_trace_msg(conf->mddev->queue,
3897                                           "raid5 rmw %llu %d",
3898                                           (unsigned long long)sh->sector, rmw);
3899                 for (i = disks; i--; ) {
3900                         struct r5dev *dev = &sh->dev[i];
3901                         if (test_bit(R5_InJournal, &dev->flags) &&
3902                             dev->page == dev->orig_page &&
3903                             !test_bit(R5_LOCKED, &sh->dev[sh->pd_idx].flags)) {
3904                                 /* alloc page for prexor */
3905                                 struct page *p = alloc_page(GFP_NOIO);
3906
3907                                 if (p) {
3908                                         dev->orig_page = p;
3909                                         continue;
3910                                 }
3911
3912                                 /*
3913                                  * alloc_page() failed, try use
3914                                  * disk_info->extra_page
3915                                  */
3916                                 if (!test_and_set_bit(R5C_EXTRA_PAGE_IN_USE,
3917                                                       &conf->cache_state)) {
3918                                         r5c_use_extra_page(sh);
3919                                         break;
3920                                 }
3921
3922                                 /* extra_page in use, add to delayed_list */
3923                                 set_bit(STRIPE_DELAYED, &sh->state);
3924                                 s->waiting_extra_page = 1;
3925                                 return -EAGAIN;
3926                         }
3927                 }
3928
3929                 for (i = disks; i--; ) {
3930                         struct r5dev *dev = &sh->dev[i];
3931                         if (((dev->towrite && !delay_towrite(conf, dev, s)) ||
3932                              i == sh->pd_idx || i == sh->qd_idx ||
3933                              test_bit(R5_InJournal, &dev->flags)) &&
3934                             !test_bit(R5_LOCKED, &dev->flags) &&
3935                             !(uptodate_for_rmw(dev) ||
3936                               test_bit(R5_Wantcompute, &dev->flags)) &&
3937                             test_bit(R5_Insync, &dev->flags)) {
3938                                 if (test_bit(STRIPE_PREREAD_ACTIVE,
3939                                              &sh->state)) {
3940                                         pr_debug("Read_old block %d for r-m-w\n",
3941                                                  i);
3942                                         set_bit(R5_LOCKED, &dev->flags);
3943                                         set_bit(R5_Wantread, &dev->flags);
3944                                         s->locked++;
3945                                 } else {
3946                                         set_bit(STRIPE_DELAYED, &sh->state);
3947                                         set_bit(STRIPE_HANDLE, &sh->state);
3948                                 }
3949                         }
3950                 }
3951         }
3952         if ((rcw < rmw || (rcw == rmw && conf->rmw_level != PARITY_PREFER_RMW)) && rcw > 0) {
3953                 /* want reconstruct write, but need to get some data */
3954                 int qread =0;
3955                 rcw = 0;
3956                 for (i = disks; i--; ) {
3957                         struct r5dev *dev = &sh->dev[i];
3958                         if (!test_bit(R5_OVERWRITE, &dev->flags) &&
3959                             i != sh->pd_idx && i != sh->qd_idx &&
3960                             !test_bit(R5_LOCKED, &dev->flags) &&
3961                             !(test_bit(R5_UPTODATE, &dev->flags) ||
3962                               test_bit(R5_Wantcompute, &dev->flags))) {
3963                                 rcw++;
3964                                 if (test_bit(R5_Insync, &dev->flags) &&
3965                                     test_bit(STRIPE_PREREAD_ACTIVE,
3966                                              &sh->state)) {
3967                                         pr_debug("Read_old block "
3968                                                 "%d for Reconstruct\n", i);
3969                                         set_bit(R5_LOCKED, &dev->flags);
3970                                         set_bit(R5_Wantread, &dev->flags);
3971                                         s->locked++;
3972                                         qread++;
3973                                 } else {
3974                                         set_bit(STRIPE_DELAYED, &sh->state);
3975                                         set_bit(STRIPE_HANDLE, &sh->state);
3976                                 }
3977                         }
3978                 }
3979                 if (rcw && conf->mddev->queue)
3980                         blk_add_trace_msg(conf->mddev->queue, "raid5 rcw %llu %d %d %d",
3981                                           (unsigned long long)sh->sector,
3982                                           rcw, qread, test_bit(STRIPE_DELAYED, &sh->state));
3983         }
3984
3985         if (rcw > disks && rmw > disks &&
3986             !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3987                 set_bit(STRIPE_DELAYED, &sh->state);
3988
3989         /* now if nothing is locked, and if we have enough data,
3990          * we can start a write request
3991          */
3992         /* since handle_stripe can be called at any time we need to handle the
3993          * case where a compute block operation has been submitted and then a
3994          * subsequent call wants to start a write request.  raid_run_ops only
3995          * handles the case where compute block and reconstruct are requested
3996          * simultaneously.  If this is not the case then new writes need to be
3997          * held off until the compute completes.
3998          */
3999         if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
4000             (s->locked == 0 && (rcw == 0 || rmw == 0) &&
4001              !test_bit(STRIPE_BIT_DELAY, &sh->state)))
4002                 schedule_reconstruction(sh, s, rcw == 0, 0);
4003         return 0;
4004 }
4005
4006 static void handle_parity_checks5(struct r5conf *conf, struct stripe_head *sh,
4007                                 struct stripe_head_state *s, int disks)
4008 {
4009         struct r5dev *dev = NULL;
4010
4011         BUG_ON(sh->batch_head);
4012         set_bit(STRIPE_HANDLE, &sh->state);
4013
4014         switch (sh->check_state) {
4015         case check_state_idle:
4016                 /* start a new check operation if there are no failures */
4017                 if (s->failed == 0) {
4018                         BUG_ON(s->uptodate != disks);
4019                         sh->check_state = check_state_run;
4020                         set_bit(STRIPE_OP_CHECK, &s->ops_request);
4021                         clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
4022                         s->uptodate--;
4023                         break;
4024                 }
4025                 dev = &sh->dev[s->failed_num[0]];
4026                 /* fall through */
4027         case check_state_compute_result:
4028                 sh->check_state = check_state_idle;
4029                 if (!dev)
4030                         dev = &sh->dev[sh->pd_idx];
4031
4032                 /* check that a write has not made the stripe insync */
4033                 if (test_bit(STRIPE_INSYNC, &sh->state))
4034                         break;
4035
4036                 /* either failed parity check, or recovery is happening */
4037                 BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
4038                 BUG_ON(s->uptodate != disks);
4039
4040                 set_bit(R5_LOCKED, &dev->flags);
4041                 s->locked++;
4042                 set_bit(R5_Wantwrite, &dev->flags);
4043
4044                 clear_bit(STRIPE_DEGRADED, &sh->state);
4045                 set_bit(STRIPE_INSYNC, &sh->state);
4046                 break;
4047         case check_state_run:
4048                 break; /* we will be called again upon completion */
4049         case check_state_check_result:
4050                 sh->check_state = check_state_idle;
4051
4052                 /* if a failure occurred during the check operation, leave
4053                  * STRIPE_INSYNC not set and let the stripe be handled again
4054                  */
4055                 if (s->failed)
4056                         break;
4057
4058                 /* handle a successful check operation, if parity is correct
4059                  * we are done.  Otherwise update the mismatch count and repair
4060                  * parity if !MD_RECOVERY_CHECK
4061                  */
4062                 if ((sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) == 0)
4063                         /* parity is correct (on disc,
4064                          * not in buffer any more)
4065                          */
4066                         set_bit(STRIPE_INSYNC, &sh->state);
4067                 else {
4068                         atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
4069                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
4070                                 /* don't try to repair!! */
4071                                 set_bit(STRIPE_INSYNC, &sh->state);
4072                         else {
4073                                 sh->check_state = check_state_compute_run;
4074                                 set_bit(STRIPE_COMPUTE_RUN, &sh->state);
4075                                 set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
4076                                 set_bit(R5_Wantcompute,
4077                                         &sh->dev[sh->pd_idx].flags);
4078                                 sh->ops.target = sh->pd_idx;
4079                                 sh->ops.target2 = -1;
4080                                 s->uptodate++;
4081                         }
4082                 }
4083                 break;
4084         case check_state_compute_run:
4085                 break;
4086         default:
4087                 pr_err("%s: unknown check_state: %d sector: %llu\n",
4088                        __func__, sh->check_state,
4089                        (unsigned long long) sh->sector);
4090                 BUG();
4091         }
4092 }
4093
4094 static void handle_parity_checks6(struct r5conf *conf, struct stripe_head *sh,
4095                                   struct stripe_head_state *s,
4096                                   int disks)
4097 {
4098         int pd_idx = sh->pd_idx;
4099         int qd_idx = sh->qd_idx;
4100         struct r5dev *dev;
4101
4102         BUG_ON(sh->batch_head);
4103         set_bit(STRIPE_HANDLE, &sh->state);
4104
4105         BUG_ON(s->failed > 2);
4106
4107         /* Want to check and possibly repair P and Q.
4108          * However there could be one 'failed' device, in which
4109          * case we can only check one of them, possibly using the
4110          * other to generate missing data
4111          */
4112
4113         switch (sh->check_state) {
4114         case check_state_idle:
4115                 /* start a new check operation if there are < 2 failures */
4116                 if (s->failed == s->q_failed) {
4117                         /* The only possible failed device holds Q, so it
4118                          * makes sense to check P (If anything else were failed,
4119                          * we would have used P to recreate it).
4120                          */
4121                         sh->check_state = check_state_run;
4122                 }
4123                 if (!s->q_failed && s->failed < 2) {
4124                         /* Q is not failed, and we didn't use it to generate
4125                          * anything, so it makes sense to check it
4126                          */
4127                         if (sh->check_state == check_state_run)
4128                                 sh->check_state = check_state_run_pq;
4129                         else
4130                                 sh->check_state = check_state_run_q;
4131                 }
4132
4133                 /* discard potentially stale zero_sum_result */
4134                 sh->ops.zero_sum_result = 0;
4135
4136                 if (sh->check_state == check_state_run) {
4137                         /* async_xor_zero_sum destroys the contents of P */
4138                         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
4139                         s->uptodate--;
4140                 }
4141                 if (sh->check_state >= check_state_run &&
4142                     sh->check_state <= check_state_run_pq) {
4143                         /* async_syndrome_zero_sum preserves P and Q, so
4144                          * no need to mark them !uptodate here
4145                          */
4146                         set_bit(STRIPE_OP_CHECK, &s->ops_request);
4147                         break;
4148                 }
4149
4150                 /* we have 2-disk failure */
4151                 BUG_ON(s->failed != 2);
4152                 /* fall through */
4153         case check_state_compute_result:
4154                 sh->check_state = check_state_idle;
4155
4156                 /* check that a write has not made the stripe insync */
4157                 if (test_bit(STRIPE_INSYNC, &sh->state))
4158                         break;
4159
4160                 /* now write out any block on a failed drive,
4161                  * or P or Q if they were recomputed
4162                  */
4163                 BUG_ON(s->uptodate < disks - 1); /* We don't need Q to recover */
4164                 if (s->failed == 2) {
4165                         dev = &sh->dev[s->failed_num[1]];
4166                         s->locked++;
4167                         set_bit(R5_LOCKED, &dev->flags);
4168                         set_bit(R5_Wantwrite, &dev->flags);
4169                 }
4170                 if (s->failed >= 1) {
4171                         dev = &sh->dev[s->failed_num[0]];
4172                         s->locked++;
4173                         set_bit(R5_LOCKED, &dev->flags);
4174                         set_bit(R5_Wantwrite, &dev->flags);
4175                 }
4176                 if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
4177                         dev = &sh->dev[pd_idx];
4178                         s->locked++;
4179                         set_bit(R5_LOCKED, &dev->flags);
4180                         set_bit(R5_Wantwrite, &dev->flags);
4181                 }
4182                 if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
4183                         dev = &sh->dev[qd_idx];
4184                         s->locked++;
4185                         set_bit(R5_LOCKED, &dev->flags);
4186                         set_bit(R5_Wantwrite, &dev->flags);
4187                 }
4188                 clear_bit(STRIPE_DEGRADED, &sh->state);
4189
4190                 set_bit(STRIPE_INSYNC, &sh->state);
4191                 break;
4192         case check_state_run:
4193         case check_state_run_q:
4194         case check_state_run_pq:
4195                 break; /* we will be called again upon completion */
4196         case check_state_check_result:
4197                 sh->check_state = check_state_idle;
4198
4199                 /* handle a successful check operation, if parity is correct
4200                  * we are done.  Otherwise update the mismatch count and repair
4201                  * parity if !MD_RECOVERY_CHECK
4202                  */
4203                 if (sh->ops.zero_sum_result == 0) {
4204                         /* both parities are correct */
4205                         if (!s->failed)
4206                                 set_bit(STRIPE_INSYNC, &sh->state);
4207                         else {
4208                                 /* in contrast to the raid5 case we can validate
4209                                  * parity, but still have a failure to write
4210                                  * back
4211                                  */
4212                                 sh->check_state = check_state_compute_result;
4213                                 /* Returning at this point means that we may go
4214                                  * off and bring p and/or q uptodate again so
4215                                  * we make sure to check zero_sum_result again
4216                                  * to verify if p or q need writeback
4217                                  */
4218                         }
4219                 } else {
4220                         atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
4221                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
4222                                 /* don't try to repair!! */
4223                                 set_bit(STRIPE_INSYNC, &sh->state);
4224                         else {
4225                                 int *target = &sh->ops.target;
4226
4227                                 sh->ops.target = -1;
4228                                 sh->ops.target2 = -1;
4229                                 sh->check_state = check_state_compute_run;
4230                                 set_bit(STRIPE_COMPUTE_RUN, &sh->state);
4231                                 set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
4232                                 if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
4233                                         set_bit(R5_Wantcompute,
4234                                                 &sh->dev[pd_idx].flags);
4235                                         *target = pd_idx;
4236                                         target = &sh->ops.target2;
4237                                         s->uptodate++;
4238                                 }
4239                                 if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
4240                                         set_bit(R5_Wantcompute,
4241                                                 &sh->dev[qd_idx].flags);
4242                                         *target = qd_idx;
4243                                         s->uptodate++;
4244                                 }
4245                         }
4246                 }
4247                 break;
4248         case check_state_compute_run:
4249                 break;
4250         default:
4251                 pr_warn("%s: unknown check_state: %d sector: %llu\n",
4252                         __func__, sh->check_state,
4253                         (unsigned long long) sh->sector);
4254                 BUG();
4255         }
4256 }
4257
4258 static void handle_stripe_expansion(struct r5conf *conf, struct stripe_head *sh)
4259 {
4260         int i;
4261
4262         /* We have read all the blocks in this stripe and now we need to
4263          * copy some of them into a target stripe for expand.
4264          */
4265         struct dma_async_tx_descriptor *tx = NULL;
4266         BUG_ON(sh->batch_head);
4267         clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
4268         for (i = 0; i < sh->disks; i++)
4269                 if (i != sh->pd_idx && i != sh->qd_idx) {
4270                         int dd_idx, j;
4271                         struct stripe_head *sh2;
4272                         struct async_submit_ctl submit;
4273
4274                         sector_t bn = raid5_compute_blocknr(sh, i, 1);
4275                         sector_t s = raid5_compute_sector(conf, bn, 0,
4276                                                           &dd_idx, NULL);
4277                         sh2 = raid5_get_active_stripe(conf, s, 0, 1, 1);
4278                         if (sh2 == NULL)
4279                                 /* so far only the early blocks of this stripe
4280                                  * have been requested.  When later blocks
4281                                  * get requested, we will try again
4282                                  */
4283                                 continue;
4284                         if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
4285                            test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
4286                                 /* must have already done this block */
4287                                 raid5_release_stripe(sh2);
4288                                 continue;
4289                         }
4290
4291                         /* place all the copies on one channel */
4292                         init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
4293                         tx = async_memcpy(sh2->dev[dd_idx].page,
4294                                           sh->dev[i].page, 0, 0, STRIPE_SIZE,
4295                                           &submit);
4296
4297                         set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
4298                         set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
4299                         for (j = 0; j < conf->raid_disks; j++)
4300                                 if (j != sh2->pd_idx &&
4301                                     j != sh2->qd_idx &&
4302                                     !test_bit(R5_Expanded, &sh2->dev[j].flags))
4303                                         break;
4304                         if (j == conf->raid_disks) {
4305                                 set_bit(STRIPE_EXPAND_READY, &sh2->state);
4306                                 set_bit(STRIPE_HANDLE, &sh2->state);
4307                         }
4308                         raid5_release_stripe(sh2);
4309
4310                 }
4311         /* done submitting copies, wait for them to complete */
4312         async_tx_quiesce(&tx);
4313 }
4314
4315 /*
4316  * handle_stripe - do things to a stripe.
4317  *
4318  * We lock the stripe by setting STRIPE_ACTIVE and then examine the
4319  * state of various bits to see what needs to be done.
4320  * Possible results:
4321  *    return some read requests which now have data
4322  *    return some write requests which are safely on storage
4323  *    schedule a read on some buffers
4324  *    schedule a write of some buffers
4325  *    return confirmation of parity correctness
4326  *
4327  */
4328
4329 static void analyse_stripe(struct stripe_head *sh, struct stripe_head_state *s)
4330 {
4331         struct r5conf *conf = sh->raid_conf;
4332         int disks = sh->disks;
4333         struct r5dev *dev;
4334         int i;
4335         int do_recovery = 0;
4336
4337         memset(s, 0, sizeof(*s));
4338
4339         s->expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state) && !sh->batch_head;
4340         s->expanded = test_bit(STRIPE_EXPAND_READY, &sh->state) && !sh->batch_head;
4341         s->failed_num[0] = -1;
4342         s->failed_num[1] = -1;
4343         s->log_failed = r5l_log_disk_error(conf);
4344
4345         /* Now to look around and see what can be done */
4346         rcu_read_lock();
4347         for (i=disks; i--; ) {
4348                 struct md_rdev *rdev;
4349                 sector_t first_bad;
4350                 int bad_sectors;
4351                 int is_bad = 0;
4352
4353                 dev = &sh->dev[i];
4354
4355                 pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
4356                          i, dev->flags,
4357                          dev->toread, dev->towrite, dev->written);
4358                 /* maybe we can reply to a read
4359                  *
4360                  * new wantfill requests are only permitted while
4361                  * ops_complete_biofill is guaranteed to be inactive
4362                  */
4363                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
4364                     !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
4365                         set_bit(R5_Wantfill, &dev->flags);
4366
4367                 /* now count some things */
4368                 if (test_bit(R5_LOCKED, &dev->flags))
4369                         s->locked++;
4370                 if (test_bit(R5_UPTODATE, &dev->flags))
4371                         s->uptodate++;
4372                 if (test_bit(R5_Wantcompute, &dev->flags)) {
4373                         s->compute++;
4374                         BUG_ON(s->compute > 2);
4375                 }
4376
4377                 if (test_bit(R5_Wantfill, &dev->flags))
4378                         s->to_fill++;
4379                 else if (dev->toread)
4380                         s->to_read++;
4381                 if (dev->towrite) {
4382                         s->to_write++;
4383                         if (!test_bit(R5_OVERWRITE, &dev->flags))
4384                                 s->non_overwrite++;
4385                 }
4386                 if (dev->written)
4387                         s->written++;
4388                 /* Prefer to use the replacement for reads, but only
4389                  * if it is recovered enough and has no bad blocks.
4390                  */
4391                 rdev = rcu_dereference(conf->disks[i].replacement);
4392                 if (rdev && !test_bit(Faulty, &rdev->flags) &&
4393                     rdev->recovery_offset >= sh->sector + STRIPE_SECTORS &&
4394                     !is_badblock(rdev, sh->sector, STRIPE_SECTORS,
4395                                  &first_bad, &bad_sectors))
4396                         set_bit(R5_ReadRepl, &dev->flags);
4397                 else {
4398                         if (rdev && !test_bit(Faulty, &rdev->flags))
4399                                 set_bit(R5_NeedReplace, &dev->flags);
4400                         else
4401                                 clear_bit(R5_NeedReplace, &dev->flags);
4402                         rdev = rcu_dereference(conf->disks[i].rdev);
4403                         clear_bit(R5_ReadRepl, &dev->flags);
4404                 }
4405                 if (rdev && test_bit(Faulty, &rdev->flags))
4406                         rdev = NULL;
4407                 if (rdev) {
4408                         is_bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
4409                                              &first_bad, &bad_sectors);
4410                         if (s->blocked_rdev == NULL
4411                             && (test_bit(Blocked, &rdev->flags)
4412                                 || is_bad < 0)) {
4413                                 if (is_bad < 0)
4414                                         set_bit(BlockedBadBlocks,
4415                                                 &rdev->flags);
4416                                 s->blocked_rdev = rdev;
4417                                 atomic_inc(&rdev->nr_pending);
4418                         }
4419                 }
4420                 clear_bit(R5_Insync, &dev->flags);
4421                 if (!rdev)
4422                         /* Not in-sync */;
4423                 else if (is_bad) {
4424                         /* also not in-sync */
4425                         if (!test_bit(WriteErrorSeen, &rdev->flags) &&
4426                             test_bit(R5_UPTODATE, &dev->flags)) {
4427                                 /* treat as in-sync, but with a read error
4428                                  * which we can now try to correct
4429                                  */
4430                                 set_bit(R5_Insync, &dev->flags);
4431                                 set_bit(R5_ReadError, &dev->flags);
4432                         }
4433                 } else if (test_bit(In_sync, &rdev->flags))
4434                         set_bit(R5_Insync, &dev->flags);
4435                 else if (sh->sector + STRIPE_SECTORS <= rdev->recovery_offset)
4436                         /* in sync if before recovery_offset */
4437                         set_bit(R5_Insync, &dev->flags);
4438                 else if (test_bit(R5_UPTODATE, &dev->flags) &&
4439                          test_bit(R5_Expanded, &dev->flags))
4440                         /* If we've reshaped into here, we assume it is Insync.
4441                          * We will shortly update recovery_offset to make
4442                          * it official.
4443                          */
4444                         set_bit(R5_Insync, &dev->flags);
4445
4446                 if (test_bit(R5_WriteError, &dev->flags)) {
4447                         /* This flag does not apply to '.replacement'
4448                          * only to .rdev, so make sure to check that*/
4449                         struct md_rdev *rdev2 = rcu_dereference(
4450                                 conf->disks[i].rdev);
4451                         if (rdev2 == rdev)
4452                                 clear_bit(R5_Insync, &dev->flags);
4453                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4454                                 s->handle_bad_blocks = 1;
4455                                 atomic_inc(&rdev2->nr_pending);
4456                         } else
4457                                 clear_bit(R5_WriteError, &dev->flags);
4458                 }
4459                 if (test_bit(R5_MadeGood, &dev->flags)) {
4460                         /* This flag does not apply to '.replacement'
4461                          * only to .rdev, so make sure to check that*/
4462                         struct md_rdev *rdev2 = rcu_dereference(
4463                                 conf->disks[i].rdev);
4464                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4465                                 s->handle_bad_blocks = 1;
4466                                 atomic_inc(&rdev2->nr_pending);
4467                         } else
4468                                 clear_bit(R5_MadeGood, &dev->flags);
4469                 }
4470                 if (test_bit(R5_MadeGoodRepl, &dev->flags)) {
4471                         struct md_rdev *rdev2 = rcu_dereference(
4472                                 conf->disks[i].replacement);
4473                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4474                                 s->handle_bad_blocks = 1;
4475                                 atomic_inc(&rdev2->nr_pending);
4476                         } else
4477                                 clear_bit(R5_MadeGoodRepl, &dev->flags);
4478                 }
4479                 if (!test_bit(R5_Insync, &dev->flags)) {
4480                         /* The ReadError flag will just be confusing now */
4481                         clear_bit(R5_ReadError, &dev->flags);
4482                         clear_bit(R5_ReWrite, &dev->flags);
4483                 }
4484                 if (test_bit(R5_ReadError, &dev->flags))
4485                         clear_bit(R5_Insync, &dev->flags);
4486                 if (!test_bit(R5_Insync, &dev->flags)) {
4487                         if (s->failed < 2)
4488                                 s->failed_num[s->failed] = i;
4489                         s->failed++;
4490                         if (rdev && !test_bit(Faulty, &rdev->flags))
4491                                 do_recovery = 1;
4492                 }
4493
4494                 if (test_bit(R5_InJournal, &dev->flags))
4495                         s->injournal++;
4496                 if (test_bit(R5_InJournal, &dev->flags) && dev->written)
4497                         s->just_cached++;
4498         }
4499         if (test_bit(STRIPE_SYNCING, &sh->state)) {
4500                 /* If there is a failed device being replaced,
4501                  *     we must be recovering.
4502                  * else if we are after recovery_cp, we must be syncing
4503                  * else if MD_RECOVERY_REQUESTED is set, we also are syncing.
4504                  * else we can only be replacing
4505                  * sync and recovery both need to read all devices, and so
4506                  * use the same flag.
4507                  */
4508                 if (do_recovery ||
4509                     sh->sector >= conf->mddev->recovery_cp ||
4510                     test_bit(MD_RECOVERY_REQUESTED, &(conf->mddev->recovery)))
4511                         s->syncing = 1;
4512                 else
4513                         s->replacing = 1;
4514         }
4515         rcu_read_unlock();
4516 }
4517
4518 static int clear_batch_ready(struct stripe_head *sh)
4519 {
4520         /* Return '1' if this is a member of batch, or
4521          * '0' if it is a lone stripe or a head which can now be
4522          * handled.
4523          */
4524         struct stripe_head *tmp;
4525         if (!test_and_clear_bit(STRIPE_BATCH_READY, &sh->state))
4526                 return (sh->batch_head && sh->batch_head != sh);
4527         spin_lock(&sh->stripe_lock);
4528         if (!sh->batch_head) {
4529                 spin_unlock(&sh->stripe_lock);
4530                 return 0;
4531         }
4532
4533         /*
4534          * this stripe could be added to a batch list before we check
4535          * BATCH_READY, skips it
4536          */
4537         if (sh->batch_head != sh) {
4538                 spin_unlock(&sh->stripe_lock);
4539                 return 1;
4540         }
4541         spin_lock(&sh->batch_lock);
4542         list_for_each_entry(tmp, &sh->batch_list, batch_list)
4543                 clear_bit(STRIPE_BATCH_READY, &tmp->state);
4544         spin_unlock(&sh->batch_lock);
4545         spin_unlock(&sh->stripe_lock);
4546
4547         /*
4548          * BATCH_READY is cleared, no new stripes can be added.
4549          * batch_list can be accessed without lock
4550          */
4551         return 0;
4552 }
4553
4554 static void break_stripe_batch_list(struct stripe_head *head_sh,
4555                                     unsigned long handle_flags)
4556 {
4557         struct stripe_head *sh, *next;
4558         int i;
4559         int do_wakeup = 0;
4560
4561         list_for_each_entry_safe(sh, next, &head_sh->batch_list, batch_list) {
4562
4563                 list_del_init(&sh->batch_list);
4564
4565                 WARN_ONCE(sh->state & ((1 << STRIPE_ACTIVE) |
4566                                           (1 << STRIPE_SYNCING) |
4567                                           (1 << STRIPE_REPLACED) |
4568                                           (1 << STRIPE_DELAYED) |
4569                                           (1 << STRIPE_BIT_DELAY) |
4570                                           (1 << STRIPE_FULL_WRITE) |
4571                                           (1 << STRIPE_BIOFILL_RUN) |
4572                                           (1 << STRIPE_COMPUTE_RUN)  |
4573                                           (1 << STRIPE_OPS_REQ_PENDING) |
4574                                           (1 << STRIPE_DISCARD) |
4575                                           (1 << STRIPE_BATCH_READY) |
4576                                           (1 << STRIPE_BATCH_ERR) |
4577                                           (1 << STRIPE_BITMAP_PENDING)),
4578                         "stripe state: %lx\n", sh->state);
4579                 WARN_ONCE(head_sh->state & ((1 << STRIPE_DISCARD) |
4580                                               (1 << STRIPE_REPLACED)),
4581                         "head stripe state: %lx\n", head_sh->state);
4582
4583                 set_mask_bits(&sh->state, ~(STRIPE_EXPAND_SYNC_FLAGS |
4584                                             (1 << STRIPE_PREREAD_ACTIVE) |
4585                                             (1 << STRIPE_DEGRADED)),
4586                               head_sh->state & (1 << STRIPE_INSYNC));
4587
4588                 sh->check_state = head_sh->check_state;
4589                 sh->reconstruct_state = head_sh->reconstruct_state;
4590                 for (i = 0; i < sh->disks; i++) {
4591                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
4592                                 do_wakeup = 1;
4593                         sh->dev[i].flags = head_sh->dev[i].flags &
4594                                 (~((1 << R5_WriteError) | (1 << R5_Overlap)));
4595                 }
4596                 spin_lock_irq(&sh->stripe_lock);
4597                 sh->batch_head = NULL;
4598                 spin_unlock_irq(&sh->stripe_lock);
4599                 if (handle_flags == 0 ||
4600                     sh->state & handle_flags)
4601                         set_bit(STRIPE_HANDLE, &sh->state);
4602                 raid5_release_stripe(sh);
4603         }
4604         spin_lock_irq(&head_sh->stripe_lock);
4605         head_sh->batch_head = NULL;
4606         spin_unlock_irq(&head_sh->stripe_lock);
4607         for (i = 0; i < head_sh->disks; i++)
4608                 if (test_and_clear_bit(R5_Overlap, &head_sh->dev[i].flags))
4609                         do_wakeup = 1;
4610         if (head_sh->state & handle_flags)
4611                 set_bit(STRIPE_HANDLE, &head_sh->state);
4612
4613         if (do_wakeup)
4614                 wake_up(&head_sh->raid_conf->wait_for_overlap);
4615 }
4616
4617 static void handle_stripe(struct stripe_head *sh)
4618 {
4619         struct stripe_head_state s;
4620         struct r5conf *conf = sh->raid_conf;
4621         int i;
4622         int prexor;
4623         int disks = sh->disks;
4624         struct r5dev *pdev, *qdev;
4625
4626         clear_bit(STRIPE_HANDLE, &sh->state);
4627         if (test_and_set_bit_lock(STRIPE_ACTIVE, &sh->state)) {
4628                 /* already being handled, ensure it gets handled
4629                  * again when current action finishes */
4630                 set_bit(STRIPE_HANDLE, &sh->state);
4631                 return;
4632         }
4633
4634         if (clear_batch_ready(sh) ) {
4635                 clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
4636                 return;
4637         }
4638
4639         if (test_and_clear_bit(STRIPE_BATCH_ERR, &sh->state))
4640                 break_stripe_batch_list(sh, 0);
4641
4642         if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state) && !sh->batch_head) {
4643                 spin_lock(&sh->stripe_lock);
4644                 /* Cannot process 'sync' concurrently with 'discard' */
4645                 if (!test_bit(STRIPE_DISCARD, &sh->state) &&
4646                     test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
4647                         set_bit(STRIPE_SYNCING, &sh->state);
4648                         clear_bit(STRIPE_INSYNC, &sh->state);
4649                         clear_bit(STRIPE_REPLACED, &sh->state);
4650                 }
4651                 spin_unlock(&sh->stripe_lock);
4652         }
4653         clear_bit(STRIPE_DELAYED, &sh->state);
4654
4655         pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
4656                 "pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
4657                (unsigned long long)sh->sector, sh->state,
4658                atomic_read(&sh->count), sh->pd_idx, sh->qd_idx,
4659                sh->check_state, sh->reconstruct_state);
4660
4661         analyse_stripe(sh, &s);
4662
4663         if (test_bit(STRIPE_LOG_TRAPPED, &sh->state))
4664                 goto finish;
4665
4666         if (s.handle_bad_blocks ||
4667             test_bit(MD_SB_CHANGE_PENDING, &conf->mddev->sb_flags)) {
4668                 set_bit(STRIPE_HANDLE, &sh->state);
4669                 goto finish;
4670         }
4671
4672         if (unlikely(s.blocked_rdev)) {
4673                 if (s.syncing || s.expanding || s.expanded ||
4674                     s.replacing || s.to_write || s.written) {
4675                         set_bit(STRIPE_HANDLE, &sh->state);
4676                         goto finish;
4677                 }
4678                 /* There is nothing for the blocked_rdev to block */
4679                 rdev_dec_pending(s.blocked_rdev, conf->mddev);
4680                 s.blocked_rdev = NULL;
4681         }
4682
4683         if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
4684                 set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
4685                 set_bit(STRIPE_BIOFILL_RUN, &sh->state);
4686         }
4687
4688         pr_debug("locked=%d uptodate=%d to_read=%d"
4689                " to_write=%d failed=%d failed_num=%d,%d\n",
4690                s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
4691                s.failed_num[0], s.failed_num[1]);
4692         /* check if the array has lost more than max_degraded devices and,
4693          * if so, some requests might need to be failed.
4694          */
4695         if (s.failed > conf->max_degraded || s.log_failed) {
4696                 sh->check_state = 0;
4697                 sh->reconstruct_state = 0;
4698                 break_stripe_batch_list(sh, 0);
4699                 if (s.to_read+s.to_write+s.written)
4700                         handle_failed_stripe(conf, sh, &s, disks);
4701                 if (s.syncing + s.replacing)
4702                         handle_failed_sync(conf, sh, &s);
4703         }
4704
4705         /* Now we check to see if any write operations have recently
4706          * completed
4707          */
4708         prexor = 0;
4709         if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
4710                 prexor = 1;
4711         if (sh->reconstruct_state == reconstruct_state_drain_result ||
4712             sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
4713                 sh->reconstruct_state = reconstruct_state_idle;
4714
4715                 /* All the 'written' buffers and the parity block are ready to
4716                  * be written back to disk
4717                  */
4718                 BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags) &&
4719                        !test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags));
4720                 BUG_ON(sh->qd_idx >= 0 &&
4721                        !test_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags) &&
4722                        !test_bit(R5_Discard, &sh->dev[sh->qd_idx].flags));
4723                 for (i = disks; i--; ) {
4724                         struct r5dev *dev = &sh->dev[i];
4725                         if (test_bit(R5_LOCKED, &dev->flags) &&
4726                                 (i == sh->pd_idx || i == sh->qd_idx ||
4727                                  dev->written || test_bit(R5_InJournal,
4728                                                           &dev->flags))) {
4729                                 pr_debug("Writing block %d\n", i);
4730                                 set_bit(R5_Wantwrite, &dev->flags);
4731                                 if (prexor)
4732                                         continue;
4733                                 if (s.failed > 1)
4734                                         continue;
4735                                 if (!test_bit(R5_Insync, &dev->flags) ||
4736                                     ((i == sh->pd_idx || i == sh->qd_idx)  &&
4737                                      s.failed == 0))
4738                                         set_bit(STRIPE_INSYNC, &sh->state);
4739                         }
4740                 }
4741                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4742                         s.dec_preread_active = 1;
4743         }
4744
4745         /*
4746          * might be able to return some write requests if the parity blocks
4747          * are safe, or on a failed drive
4748          */
4749         pdev = &sh->dev[sh->pd_idx];
4750         s.p_failed = (s.failed >= 1 && s.failed_num[0] == sh->pd_idx)
4751                 || (s.failed >= 2 && s.failed_num[1] == sh->pd_idx);
4752         qdev = &sh->dev[sh->qd_idx];
4753         s.q_failed = (s.failed >= 1 && s.failed_num[0] == sh->qd_idx)
4754                 || (s.failed >= 2 && s.failed_num[1] == sh->qd_idx)
4755                 || conf->level < 6;
4756
4757         if (s.written &&
4758             (s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
4759                              && !test_bit(R5_LOCKED, &pdev->flags)
4760                              && (test_bit(R5_UPTODATE, &pdev->flags) ||
4761                                  test_bit(R5_Discard, &pdev->flags))))) &&
4762             (s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
4763                              && !test_bit(R5_LOCKED, &qdev->flags)
4764                              && (test_bit(R5_UPTODATE, &qdev->flags) ||
4765                                  test_bit(R5_Discard, &qdev->flags))))))
4766                 handle_stripe_clean_event(conf, sh, disks);
4767
4768         if (s.just_cached)
4769                 r5c_handle_cached_data_endio(conf, sh, disks);
4770         log_stripe_write_finished(sh);
4771
4772         /* Now we might consider reading some blocks, either to check/generate
4773          * parity, or to satisfy requests
4774          * or to load a block that is being partially written.
4775          */
4776         if (s.to_read || s.non_overwrite
4777             || (conf->level == 6 && s.to_write && s.failed)
4778             || (s.syncing && (s.uptodate + s.compute < disks))
4779             || s.replacing
4780             || s.expanding)
4781                 handle_stripe_fill(sh, &s, disks);
4782
4783         /*
4784          * When the stripe finishes full journal write cycle (write to journal
4785          * and raid disk), this is the clean up procedure so it is ready for
4786          * next operation.
4787          */
4788         r5c_finish_stripe_write_out(conf, sh, &s);
4789
4790         /*
4791          * Now to consider new write requests, cache write back and what else,
4792          * if anything should be read.  We do not handle new writes when:
4793          * 1/ A 'write' operation (copy+xor) is already in flight.
4794          * 2/ A 'check' operation is in flight, as it may clobber the parity
4795          *    block.
4796          * 3/ A r5c cache log write is in flight.
4797          */
4798
4799         if (!sh->reconstruct_state && !sh->check_state && !sh->log_io) {
4800                 if (!r5c_is_writeback(conf->log)) {
4801                         if (s.to_write)
4802                                 handle_stripe_dirtying(conf, sh, &s, disks);
4803                 } else { /* write back cache */
4804                         int ret = 0;
4805
4806                         /* First, try handle writes in caching phase */
4807                         if (s.to_write)
4808                                 ret = r5c_try_caching_write(conf, sh, &s,
4809                                                             disks);
4810                         /*
4811                          * If caching phase failed: ret == -EAGAIN
4812                          *    OR
4813                          * stripe under reclaim: !caching && injournal
4814                          *
4815                          * fall back to handle_stripe_dirtying()
4816                          */
4817                         if (ret == -EAGAIN ||
4818                             /* stripe under reclaim: !caching && injournal */
4819                             (!test_bit(STRIPE_R5C_CACHING, &sh->state) &&
4820                              s.injournal > 0)) {
4821                                 ret = handle_stripe_dirtying(conf, sh, &s,
4822                                                              disks);
4823                                 if (ret == -EAGAIN)
4824                                         goto finish;
4825                         }
4826                 }
4827         }
4828
4829         /* maybe we need to check and possibly fix the parity for this stripe
4830          * Any reads will already have been scheduled, so we just see if enough
4831          * data is available.  The parity check is held off while parity
4832          * dependent operations are in flight.
4833          */
4834         if (sh->check_state ||
4835             (s.syncing && s.locked == 0 &&
4836              !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
4837              !test_bit(STRIPE_INSYNC, &sh->state))) {
4838                 if (conf->level == 6)
4839                         handle_parity_checks6(conf, sh, &s, disks);
4840                 else
4841                         handle_parity_checks5(conf, sh, &s, disks);
4842         }
4843
4844         if ((s.replacing || s.syncing) && s.locked == 0
4845             && !test_bit(STRIPE_COMPUTE_RUN, &sh->state)
4846             && !test_bit(STRIPE_REPLACED, &sh->state)) {
4847                 /* Write out to replacement devices where possible */
4848                 for (i = 0; i < conf->raid_disks; i++)
4849                         if (test_bit(R5_NeedReplace, &sh->dev[i].flags)) {
4850                                 WARN_ON(!test_bit(R5_UPTODATE, &sh->dev[i].flags));
4851                                 set_bit(R5_WantReplace, &sh->dev[i].flags);
4852                                 set_bit(R5_LOCKED, &sh->dev[i].flags);
4853                                 s.locked++;
4854                         }
4855                 if (s.replacing)
4856                         set_bit(STRIPE_INSYNC, &sh->state);
4857                 set_bit(STRIPE_REPLACED, &sh->state);
4858         }
4859         if ((s.syncing || s.replacing) && s.locked == 0 &&
4860             !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
4861             test_bit(STRIPE_INSYNC, &sh->state)) {
4862                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
4863                 clear_bit(STRIPE_SYNCING, &sh->state);
4864                 if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
4865                         wake_up(&conf->wait_for_overlap);
4866         }
4867
4868         /* If the failed drives are just a ReadError, then we might need
4869          * to progress the repair/check process
4870          */
4871         if (s.failed <= conf->max_degraded && !conf->mddev->ro)
4872                 for (i = 0; i < s.failed; i++) {
4873                         struct r5dev *dev = &sh->dev[s.failed_num[i]];
4874                         if (test_bit(R5_ReadError, &dev->flags)
4875                             && !test_bit(R5_LOCKED, &dev->flags)
4876                             && test_bit(R5_UPTODATE, &dev->flags)
4877                                 ) {
4878                                 if (!test_bit(R5_ReWrite, &dev->flags)) {
4879                                         set_bit(R5_Wantwrite, &dev->flags);
4880                                         set_bit(R5_ReWrite, &dev->flags);
4881                                         set_bit(R5_LOCKED, &dev->flags);
4882                                         s.locked++;
4883                                 } else {
4884                                         /* let's read it back */
4885                                         set_bit(R5_Wantread, &dev->flags);
4886                                         set_bit(R5_LOCKED, &dev->flags);
4887                                         s.locked++;
4888                                 }
4889                         }
4890                 }
4891
4892         /* Finish reconstruct operations initiated by the expansion process */
4893         if (sh->reconstruct_state == reconstruct_state_result) {
4894                 struct stripe_head *sh_src
4895                         = raid5_get_active_stripe(conf, sh->sector, 1, 1, 1);
4896                 if (sh_src && test_bit(STRIPE_EXPAND_SOURCE, &sh_src->state)) {
4897                         /* sh cannot be written until sh_src has been read.
4898                          * so arrange for sh to be delayed a little
4899                          */
4900                         set_bit(STRIPE_DELAYED, &sh->state);
4901                         set_bit(STRIPE_HANDLE, &sh->state);
4902                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE,
4903                                               &sh_src->state))
4904                                 atomic_inc(&conf->preread_active_stripes);
4905                         raid5_release_stripe(sh_src);
4906                         goto finish;
4907                 }
4908                 if (sh_src)
4909                         raid5_release_stripe(sh_src);
4910
4911                 sh->reconstruct_state = reconstruct_state_idle;
4912                 clear_bit(STRIPE_EXPANDING, &sh->state);
4913                 for (i = conf->raid_disks; i--; ) {
4914                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
4915                         set_bit(R5_LOCKED, &sh->dev[i].flags);
4916                         s.locked++;
4917                 }
4918         }
4919
4920         if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
4921             !sh->reconstruct_state) {
4922                 /* Need to write out all blocks after computing parity */
4923                 sh->disks = conf->raid_disks;
4924                 stripe_set_idx(sh->sector, conf, 0, sh);
4925                 schedule_reconstruction(sh, &s, 1, 1);
4926         } else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
4927                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
4928                 atomic_dec(&conf->reshape_stripes);
4929                 wake_up(&conf->wait_for_overlap);
4930                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
4931         }
4932
4933         if (s.expanding && s.locked == 0 &&
4934             !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
4935                 handle_stripe_expansion(conf, sh);
4936
4937 finish:
4938         /* wait for this device to become unblocked */
4939         if (unlikely(s.blocked_rdev)) {
4940                 if (conf->mddev->external)
4941                         md_wait_for_blocked_rdev(s.blocked_rdev,
4942                                                  conf->mddev);
4943                 else
4944                         /* Internal metadata will immediately
4945                          * be written by raid5d, so we don't
4946                          * need to wait here.
4947                          */
4948                         rdev_dec_pending(s.blocked_rdev,
4949                                          conf->mddev);
4950         }
4951
4952         if (s.handle_bad_blocks)
4953                 for (i = disks; i--; ) {
4954                         struct md_rdev *rdev;
4955                         struct r5dev *dev = &sh->dev[i];
4956                         if (test_and_clear_bit(R5_WriteError, &dev->flags)) {
4957                                 /* We own a safe reference to the rdev */
4958                                 rdev = conf->disks[i].rdev;
4959                                 if (!rdev_set_badblocks(rdev, sh->sector,
4960                                                         STRIPE_SECTORS, 0))
4961                                         md_error(conf->mddev, rdev);
4962                                 rdev_dec_pending(rdev, conf->mddev);
4963                         }
4964                         if (test_and_clear_bit(R5_MadeGood, &dev->flags)) {
4965                                 rdev = conf->disks[i].rdev;
4966                                 rdev_clear_badblocks(rdev, sh->sector,
4967                                                      STRIPE_SECTORS, 0);
4968                                 rdev_dec_pending(rdev, conf->mddev);
4969                         }
4970                         if (test_and_clear_bit(R5_MadeGoodRepl, &dev->flags)) {
4971                                 rdev = conf->disks[i].replacement;
4972                                 if (!rdev)
4973                                         /* rdev have been moved down */
4974                                         rdev = conf->disks[i].rdev;
4975                                 rdev_clear_badblocks(rdev, sh->sector,
4976                                                      STRIPE_SECTORS, 0);
4977                                 rdev_dec_pending(rdev, conf->mddev);
4978                         }
4979                 }
4980
4981         if (s.ops_request)
4982                 raid_run_ops(sh, s.ops_request);
4983
4984         ops_run_io(sh, &s);
4985
4986         if (s.dec_preread_active) {
4987                 /* We delay this until after ops_run_io so that if make_request
4988                  * is waiting on a flush, it won't continue until the writes
4989                  * have actually been submitted.
4990                  */
4991                 atomic_dec(&conf->preread_active_stripes);
4992                 if (atomic_read(&conf->preread_active_stripes) <
4993                     IO_THRESHOLD)
4994                         md_wakeup_thread(conf->mddev->thread);
4995         }
4996
4997         clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
4998 }
4999
5000 static void raid5_activate_delayed(struct r5conf *conf)
5001 {
5002         if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
5003                 while (!list_empty(&conf->delayed_list)) {
5004                         struct list_head *l = conf->delayed_list.next;
5005                         struct stripe_head *sh;
5006                         sh = list_entry(l, struct stripe_head, lru);
5007                         list_del_init(l);
5008                         clear_bit(STRIPE_DELAYED, &sh->state);
5009                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5010                                 atomic_inc(&conf->preread_active_stripes);
5011                         list_add_tail(&sh->lru, &conf->hold_list);
5012                         raid5_wakeup_stripe_thread(sh);
5013                 }
5014         }
5015 }
5016
5017 static void activate_bit_delay(struct r5conf *conf,
5018         struct list_head *temp_inactive_list)
5019 {
5020         /* device_lock is held */
5021         struct list_head head;
5022         list_add(&head, &conf->bitmap_list);
5023         list_del_init(&conf->bitmap_list);
5024         while (!list_empty(&head)) {
5025                 struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
5026                 int hash;
5027                 list_del_init(&sh->lru);
5028                 atomic_inc(&sh->count);
5029                 hash = sh->hash_lock_index;
5030                 __release_stripe(conf, sh, &temp_inactive_list[hash]);
5031         }
5032 }
5033
5034 static int raid5_congested(struct mddev *mddev, int bits)
5035 {
5036         struct r5conf *conf = mddev->private;
5037
5038         /* No difference between reads and writes.  Just check
5039          * how busy the stripe_cache is
5040          */
5041
5042         if (test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state))
5043                 return 1;
5044
5045         /* Also checks whether there is pressure on r5cache log space */
5046         if (test_bit(R5C_LOG_TIGHT, &conf->cache_state))
5047                 return 1;
5048         if (conf->quiesce)
5049                 return 1;
5050         if (atomic_read(&conf->empty_inactive_list_nr))
5051                 return 1;
5052
5053         return 0;
5054 }
5055
5056 static int in_chunk_boundary(struct mddev *mddev, struct bio *bio)
5057 {
5058         struct r5conf *conf = mddev->private;
5059         sector_t sector = bio->bi_iter.bi_sector + get_start_sect(bio->bi_bdev);
5060         unsigned int chunk_sectors;
5061         unsigned int bio_sectors = bio_sectors(bio);
5062
5063         chunk_sectors = min(conf->chunk_sectors, conf->prev_chunk_sectors);
5064         return  chunk_sectors >=
5065                 ((sector & (chunk_sectors - 1)) + bio_sectors);
5066 }
5067
5068 /*
5069  *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
5070  *  later sampled by raid5d.
5071  */
5072 static void add_bio_to_retry(struct bio *bi,struct r5conf *conf)
5073 {
5074         unsigned long flags;
5075
5076         spin_lock_irqsave(&conf->device_lock, flags);
5077
5078         bi->bi_next = conf->retry_read_aligned_list;
5079         conf->retry_read_aligned_list = bi;
5080
5081         spin_unlock_irqrestore(&conf->device_lock, flags);
5082         md_wakeup_thread(conf->mddev->thread);
5083 }
5084
5085 static struct bio *remove_bio_from_retry(struct r5conf *conf,
5086                                          unsigned int *offset)
5087 {
5088         struct bio *bi;
5089
5090         bi = conf->retry_read_aligned;
5091         if (bi) {
5092                 *offset = conf->retry_read_offset;
5093                 conf->retry_read_aligned = NULL;
5094                 return bi;
5095         }
5096         bi = conf->retry_read_aligned_list;
5097         if(bi) {
5098                 conf->retry_read_aligned_list = bi->bi_next;
5099                 bi->bi_next = NULL;
5100                 *offset = 0;
5101         }
5102
5103         return bi;
5104 }
5105
5106 /*
5107  *  The "raid5_align_endio" should check if the read succeeded and if it
5108  *  did, call bio_endio on the original bio (having bio_put the new bio
5109  *  first).
5110  *  If the read failed..
5111  */
5112 static void raid5_align_endio(struct bio *bi)
5113 {
5114         struct bio* raid_bi  = bi->bi_private;
5115         struct mddev *mddev;
5116         struct r5conf *conf;
5117         struct md_rdev *rdev;
5118         int error = bi->bi_error;
5119
5120         bio_put(bi);
5121
5122         rdev = (void*)raid_bi->bi_next;
5123         raid_bi->bi_next = NULL;
5124         mddev = rdev->mddev;
5125         conf = mddev->private;
5126
5127         rdev_dec_pending(rdev, conf->mddev);
5128
5129         if (!error) {
5130                 trace_block_bio_complete(bdev_get_queue(raid_bi->bi_bdev),
5131                                          raid_bi, 0);
5132                 bio_endio(raid_bi);
5133                 if (atomic_dec_and_test(&conf->active_aligned_reads))
5134                         wake_up(&conf->wait_for_quiescent);
5135                 return;
5136         }
5137
5138         pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
5139
5140         add_bio_to_retry(raid_bi, conf);
5141 }
5142
5143 static int raid5_read_one_chunk(struct mddev *mddev, struct bio *raid_bio)
5144 {
5145         struct r5conf *conf = mddev->private;
5146         int dd_idx;
5147         struct bio* align_bi;
5148         struct md_rdev *rdev;
5149         sector_t end_sector;
5150
5151         if (!in_chunk_boundary(mddev, raid_bio)) {
5152                 pr_debug("%s: non aligned\n", __func__);
5153                 return 0;
5154         }
5155         /*
5156          * use bio_clone_fast to make a copy of the bio
5157          */
5158         align_bi = bio_clone_fast(raid_bio, GFP_NOIO, mddev->bio_set);
5159         if (!align_bi)
5160                 return 0;
5161         /*
5162          *   set bi_end_io to a new function, and set bi_private to the
5163          *     original bio.
5164          */
5165         align_bi->bi_end_io  = raid5_align_endio;
5166         align_bi->bi_private = raid_bio;
5167         /*
5168          *      compute position
5169          */
5170         align_bi->bi_iter.bi_sector =
5171                 raid5_compute_sector(conf, raid_bio->bi_iter.bi_sector,
5172                                      0, &dd_idx, NULL);
5173
5174         end_sector = bio_end_sector(align_bi);
5175         rcu_read_lock();
5176         rdev = rcu_dereference(conf->disks[dd_idx].replacement);
5177         if (!rdev || test_bit(Faulty, &rdev->flags) ||
5178             rdev->recovery_offset < end_sector) {
5179                 rdev = rcu_dereference(conf->disks[dd_idx].rdev);
5180                 if (rdev &&
5181                     (test_bit(Faulty, &rdev->flags) ||
5182                     !(test_bit(In_sync, &rdev->flags) ||
5183                       rdev->recovery_offset >= end_sector)))
5184                         rdev = NULL;
5185         }
5186
5187         if (r5c_big_stripe_cached(conf, align_bi->bi_iter.bi_sector)) {
5188                 rcu_read_unlock();
5189                 bio_put(align_bi);
5190                 return 0;
5191         }
5192
5193         if (rdev) {
5194                 sector_t first_bad;
5195                 int bad_sectors;
5196
5197                 atomic_inc(&rdev->nr_pending);
5198                 rcu_read_unlock();
5199                 raid_bio->bi_next = (void*)rdev;
5200                 align_bi->bi_bdev =  rdev->bdev;
5201                 bio_clear_flag(align_bi, BIO_SEG_VALID);
5202
5203                 if (is_badblock(rdev, align_bi->bi_iter.bi_sector,
5204                                 bio_sectors(align_bi),
5205                                 &first_bad, &bad_sectors)) {
5206                         bio_put(align_bi);
5207                         rdev_dec_pending(rdev, mddev);
5208                         return 0;
5209                 }
5210
5211                 /* No reshape active, so we can trust rdev->data_offset */
5212                 align_bi->bi_iter.bi_sector += rdev->data_offset;
5213
5214                 spin_lock_irq(&conf->device_lock);
5215                 wait_event_lock_irq(conf->wait_for_quiescent,
5216                                     conf->quiesce == 0,
5217                                     conf->device_lock);
5218                 atomic_inc(&conf->active_aligned_reads);
5219                 spin_unlock_irq(&conf->device_lock);
5220
5221                 if (mddev->gendisk)
5222                         trace_block_bio_remap(bdev_get_queue(align_bi->bi_bdev),
5223                                               align_bi, disk_devt(mddev->gendisk),
5224                                               raid_bio->bi_iter.bi_sector);
5225                 generic_make_request(align_bi);
5226                 return 1;
5227         } else {
5228                 rcu_read_unlock();
5229                 bio_put(align_bi);
5230                 return 0;
5231         }
5232 }
5233
5234 static struct bio *chunk_aligned_read(struct mddev *mddev, struct bio *raid_bio)
5235 {
5236         struct bio *split;
5237
5238         do {
5239                 sector_t sector = raid_bio->bi_iter.bi_sector;
5240                 unsigned chunk_sects = mddev->chunk_sectors;
5241                 unsigned sectors = chunk_sects - (sector & (chunk_sects-1));
5242
5243                 if (sectors < bio_sectors(raid_bio)) {
5244                         split = bio_split(raid_bio, sectors, GFP_NOIO, fs_bio_set);
5245                         bio_chain(split, raid_bio);
5246                 } else
5247                         split = raid_bio;
5248
5249                 if (!raid5_read_one_chunk(mddev, split)) {
5250                         if (split != raid_bio)
5251                                 generic_make_request(raid_bio);
5252                         return split;
5253                 }
5254         } while (split != raid_bio);
5255
5256         return NULL;
5257 }
5258
5259 /* __get_priority_stripe - get the next stripe to process
5260  *
5261  * Full stripe writes are allowed to pass preread active stripes up until
5262  * the bypass_threshold is exceeded.  In general the bypass_count
5263  * increments when the handle_list is handled before the hold_list; however, it
5264  * will not be incremented when STRIPE_IO_STARTED is sampled set signifying a
5265  * stripe with in flight i/o.  The bypass_count will be reset when the
5266  * head of the hold_list has changed, i.e. the head was promoted to the
5267  * handle_list.
5268  */
5269 static struct stripe_head *__get_priority_stripe(struct r5conf *conf, int group)
5270 {
5271         struct stripe_head *sh, *tmp;
5272         struct list_head *handle_list = NULL;
5273         struct r5worker_group *wg;
5274         bool second_try = !r5c_is_writeback(conf->log);
5275         bool try_loprio = test_bit(R5C_LOG_TIGHT, &conf->cache_state);
5276
5277 again:
5278         wg = NULL;
5279         sh = NULL;
5280         if (conf->worker_cnt_per_group == 0) {
5281                 handle_list = try_loprio ? &conf->loprio_list :
5282                                         &conf->handle_list;
5283         } else if (group != ANY_GROUP) {
5284                 handle_list = try_loprio ? &conf->worker_groups[group].loprio_list :
5285                                 &conf->worker_groups[group].handle_list;
5286                 wg = &conf->worker_groups[group];
5287         } else {
5288                 int i;
5289                 for (i = 0; i < conf->group_cnt; i++) {
5290                         handle_list = try_loprio ? &conf->worker_groups[i].loprio_list :
5291                                 &conf->worker_groups[i].handle_list;
5292                         wg = &conf->worker_groups[i];
5293                         if (!list_empty(handle_list))
5294                                 break;
5295                 }
5296         }
5297
5298         pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
5299                   __func__,
5300                   list_empty(handle_list) ? "empty" : "busy",
5301                   list_empty(&conf->hold_list) ? "empty" : "busy",
5302                   atomic_read(&conf->pending_full_writes), conf->bypass_count);
5303
5304         if (!list_empty(handle_list)) {
5305                 sh = list_entry(handle_list->next, typeof(*sh), lru);
5306
5307                 if (list_empty(&conf->hold_list))
5308                         conf->bypass_count = 0;
5309                 else if (!test_bit(STRIPE_IO_STARTED, &sh->state)) {
5310                         if (conf->hold_list.next == conf->last_hold)
5311                                 conf->bypass_count++;
5312                         else {
5313                                 conf->last_hold = conf->hold_list.next;
5314                                 conf->bypass_count -= conf->bypass_threshold;
5315                                 if (conf->bypass_count < 0)
5316                                         conf->bypass_count = 0;
5317                         }
5318                 }
5319         } else if (!list_empty(&conf->hold_list) &&
5320                    ((conf->bypass_threshold &&
5321                      conf->bypass_count > conf->bypass_threshold) ||
5322                     atomic_read(&conf->pending_full_writes) == 0)) {
5323
5324                 list_for_each_entry(tmp, &conf->hold_list,  lru) {
5325                         if (conf->worker_cnt_per_group == 0 ||
5326                             group == ANY_GROUP ||
5327                             !cpu_online(tmp->cpu) ||
5328                             cpu_to_group(tmp->cpu) == group) {
5329                                 sh = tmp;
5330                                 break;
5331                         }
5332                 }
5333
5334                 if (sh) {
5335                         conf->bypass_count -= conf->bypass_threshold;
5336                         if (conf->bypass_count < 0)
5337                                 conf->bypass_count = 0;
5338                 }
5339                 wg = NULL;
5340         }
5341
5342         if (!sh) {
5343                 if (second_try)
5344                         return NULL;
5345                 second_try = true;
5346                 try_loprio = !try_loprio;
5347                 goto again;
5348         }
5349
5350         if (wg) {
5351                 wg->stripes_cnt--;
5352                 sh->group = NULL;
5353         }
5354         list_del_init(&sh->lru);
5355         BUG_ON(atomic_inc_return(&sh->count) != 1);
5356         return sh;
5357 }
5358
5359 struct raid5_plug_cb {
5360         struct blk_plug_cb      cb;
5361         struct list_head        list;
5362         struct list_head        temp_inactive_list[NR_STRIPE_HASH_LOCKS];
5363 };
5364
5365 static void raid5_unplug(struct blk_plug_cb *blk_cb, bool from_schedule)
5366 {
5367         struct raid5_plug_cb *cb = container_of(
5368                 blk_cb, struct raid5_plug_cb, cb);
5369         struct stripe_head *sh;
5370         struct mddev *mddev = cb->cb.data;
5371         struct r5conf *conf = mddev->private;
5372         int cnt = 0;
5373         int hash;
5374
5375         if (cb->list.next && !list_empty(&cb->list)) {
5376                 spin_lock_irq(&conf->device_lock);
5377                 while (!list_empty(&cb->list)) {
5378                         sh = list_first_entry(&cb->list, struct stripe_head, lru);
5379                         list_del_init(&sh->lru);
5380                         /*
5381                          * avoid race release_stripe_plug() sees
5382                          * STRIPE_ON_UNPLUG_LIST clear but the stripe
5383                          * is still in our list
5384                          */
5385                         smp_mb__before_atomic();
5386                         clear_bit(STRIPE_ON_UNPLUG_LIST, &sh->state);
5387                         /*
5388                          * STRIPE_ON_RELEASE_LIST could be set here. In that
5389                          * case, the count is always > 1 here
5390                          */
5391                         hash = sh->hash_lock_index;
5392                         __release_stripe(conf, sh, &cb->temp_inactive_list[hash]);
5393                         cnt++;
5394                 }
5395                 spin_unlock_irq(&conf->device_lock);
5396         }
5397         release_inactive_stripe_list(conf, cb->temp_inactive_list,
5398                                      NR_STRIPE_HASH_LOCKS);
5399         if (mddev->queue)
5400                 trace_block_unplug(mddev->queue, cnt, !from_schedule);
5401         kfree(cb);
5402 }
5403
5404 static void release_stripe_plug(struct mddev *mddev,
5405                                 struct stripe_head *sh)
5406 {
5407         struct blk_plug_cb *blk_cb = blk_check_plugged(
5408                 raid5_unplug, mddev,
5409                 sizeof(struct raid5_plug_cb));
5410         struct raid5_plug_cb *cb;
5411
5412         if (!blk_cb) {
5413                 raid5_release_stripe(sh);
5414                 return;
5415         }
5416
5417         cb = container_of(blk_cb, struct raid5_plug_cb, cb);
5418
5419         if (cb->list.next == NULL) {
5420                 int i;
5421                 INIT_LIST_HEAD(&cb->list);
5422                 for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
5423                         INIT_LIST_HEAD(cb->temp_inactive_list + i);
5424         }
5425
5426         if (!test_and_set_bit(STRIPE_ON_UNPLUG_LIST, &sh->state))
5427                 list_add_tail(&sh->lru, &cb->list);
5428         else
5429                 raid5_release_stripe(sh);
5430 }
5431
5432 static void make_discard_request(struct mddev *mddev, struct bio *bi)
5433 {
5434         struct r5conf *conf = mddev->private;
5435         sector_t logical_sector, last_sector;
5436         struct stripe_head *sh;
5437         int stripe_sectors;
5438
5439         if (mddev->reshape_position != MaxSector)
5440                 /* Skip discard while reshape is happening */
5441                 return;
5442
5443         logical_sector = bi->bi_iter.bi_sector & ~((sector_t)STRIPE_SECTORS-1);
5444         last_sector = bi->bi_iter.bi_sector + (bi->bi_iter.bi_size>>9);
5445
5446         bi->bi_next = NULL;
5447         md_write_start(mddev, bi);
5448
5449         stripe_sectors = conf->chunk_sectors *
5450                 (conf->raid_disks - conf->max_degraded);
5451         logical_sector = DIV_ROUND_UP_SECTOR_T(logical_sector,
5452                                                stripe_sectors);
5453         sector_div(last_sector, stripe_sectors);
5454
5455         logical_sector *= conf->chunk_sectors;
5456         last_sector *= conf->chunk_sectors;
5457
5458         for (; logical_sector < last_sector;
5459              logical_sector += STRIPE_SECTORS) {
5460                 DEFINE_WAIT(w);
5461                 int d;
5462         again:
5463                 sh = raid5_get_active_stripe(conf, logical_sector, 0, 0, 0);
5464                 prepare_to_wait(&conf->wait_for_overlap, &w,
5465                                 TASK_UNINTERRUPTIBLE);
5466                 set_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
5467                 if (test_bit(STRIPE_SYNCING, &sh->state)) {
5468                         raid5_release_stripe(sh);
5469                         schedule();
5470                         goto again;
5471                 }
5472                 clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
5473                 spin_lock_irq(&sh->stripe_lock);
5474                 for (d = 0; d < conf->raid_disks; d++) {
5475                         if (d == sh->pd_idx || d == sh->qd_idx)
5476                                 continue;
5477                         if (sh->dev[d].towrite || sh->dev[d].toread) {
5478                                 set_bit(R5_Overlap, &sh->dev[d].flags);
5479                                 spin_unlock_irq(&sh->stripe_lock);
5480                                 raid5_release_stripe(sh);
5481                                 schedule();
5482                                 goto again;
5483                         }
5484                 }
5485                 set_bit(STRIPE_DISCARD, &sh->state);
5486                 finish_wait(&conf->wait_for_overlap, &w);
5487                 sh->overwrite_disks = 0;
5488                 for (d = 0; d < conf->raid_disks; d++) {
5489                         if (d == sh->pd_idx || d == sh->qd_idx)
5490                                 continue;
5491                         sh->dev[d].towrite = bi;
5492                         set_bit(R5_OVERWRITE, &sh->dev[d].flags);
5493                         bio_inc_remaining(bi);
5494                         md_write_inc(mddev, bi);
5495                         sh->overwrite_disks++;
5496                 }
5497                 spin_unlock_irq(&sh->stripe_lock);
5498                 if (conf->mddev->bitmap) {
5499                         for (d = 0;
5500                              d < conf->raid_disks - conf->max_degraded;
5501                              d++)
5502                                 bitmap_startwrite(mddev->bitmap,
5503                                                   sh->sector,
5504                                                   STRIPE_SECTORS,
5505                                                   0);
5506                         sh->bm_seq = conf->seq_flush + 1;
5507                         set_bit(STRIPE_BIT_DELAY, &sh->state);
5508                 }
5509
5510                 set_bit(STRIPE_HANDLE, &sh->state);
5511                 clear_bit(STRIPE_DELAYED, &sh->state);
5512                 if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5513                         atomic_inc(&conf->preread_active_stripes);
5514                 release_stripe_plug(mddev, sh);
5515         }
5516
5517         md_write_end(mddev);
5518         bio_endio(bi);
5519 }
5520
5521 static void raid5_make_request(struct mddev *mddev, struct bio * bi)
5522 {
5523         struct r5conf *conf = mddev->private;
5524         int dd_idx;
5525         sector_t new_sector;
5526         sector_t logical_sector, last_sector;
5527         struct stripe_head *sh;
5528         const int rw = bio_data_dir(bi);
5529         DEFINE_WAIT(w);
5530         bool do_prepare;
5531         bool do_flush = false;
5532
5533         if (unlikely(bi->bi_opf & REQ_PREFLUSH)) {
5534                 int ret = r5l_handle_flush_request(conf->log, bi);
5535
5536                 if (ret == 0)
5537                         return;
5538                 if (ret == -ENODEV) {
5539                         md_flush_request(mddev, bi);
5540                         return;
5541                 }
5542                 /* ret == -EAGAIN, fallback */
5543                 /*
5544                  * if r5l_handle_flush_request() didn't clear REQ_PREFLUSH,
5545                  * we need to flush journal device
5546                  */
5547                 do_flush = bi->bi_opf & REQ_PREFLUSH;
5548         }
5549
5550         /*
5551          * If array is degraded, better not do chunk aligned read because
5552          * later we might have to read it again in order to reconstruct
5553          * data on failed drives.
5554          */
5555         if (rw == READ && mddev->degraded == 0 &&
5556             mddev->reshape_position == MaxSector) {
5557                 bi = chunk_aligned_read(mddev, bi);
5558                 if (!bi)
5559                         return;
5560         }
5561
5562         if (unlikely(bio_op(bi) == REQ_OP_DISCARD)) {
5563                 make_discard_request(mddev, bi);
5564                 return;
5565         }
5566
5567         logical_sector = bi->bi_iter.bi_sector & ~((sector_t)STRIPE_SECTORS-1);
5568         last_sector = bio_end_sector(bi);
5569         bi->bi_next = NULL;
5570         md_write_start(mddev, bi);
5571
5572         prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
5573         for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
5574                 int previous;
5575                 int seq;
5576
5577                 do_prepare = false;
5578         retry:
5579                 seq = read_seqcount_begin(&conf->gen_lock);
5580                 previous = 0;
5581                 if (do_prepare)
5582                         prepare_to_wait(&conf->wait_for_overlap, &w,
5583                                 TASK_UNINTERRUPTIBLE);
5584                 if (unlikely(conf->reshape_progress != MaxSector)) {
5585                         /* spinlock is needed as reshape_progress may be
5586                          * 64bit on a 32bit platform, and so it might be
5587                          * possible to see a half-updated value
5588                          * Of course reshape_progress could change after
5589                          * the lock is dropped, so once we get a reference
5590                          * to the stripe that we think it is, we will have
5591                          * to check again.
5592                          */
5593                         spin_lock_irq(&conf->device_lock);
5594                         if (mddev->reshape_backwards
5595                             ? logical_sector < conf->reshape_progress
5596                             : logical_sector >= conf->reshape_progress) {
5597                                 previous = 1;
5598                         } else {
5599                                 if (mddev->reshape_backwards
5600                                     ? logical_sector < conf->reshape_safe
5601                                     : logical_sector >= conf->reshape_safe) {
5602                                         spin_unlock_irq(&conf->device_lock);
5603                                         schedule();
5604                                         do_prepare = true;
5605                                         goto retry;
5606                                 }
5607                         }
5608                         spin_unlock_irq(&conf->device_lock);
5609                 }
5610
5611                 new_sector = raid5_compute_sector(conf, logical_sector,
5612                                                   previous,
5613                                                   &dd_idx, NULL);
5614                 pr_debug("raid456: raid5_make_request, sector %llu logical %llu\n",
5615                         (unsigned long long)new_sector,
5616                         (unsigned long long)logical_sector);
5617
5618                 sh = raid5_get_active_stripe(conf, new_sector, previous,
5619                                        (bi->bi_opf & REQ_RAHEAD), 0);
5620                 if (sh) {
5621                         if (unlikely(previous)) {
5622                                 /* expansion might have moved on while waiting for a
5623                                  * stripe, so we must do the range check again.
5624                                  * Expansion could still move past after this
5625                                  * test, but as we are holding a reference to
5626                                  * 'sh', we know that if that happens,
5627                                  *  STRIPE_EXPANDING will get set and the expansion
5628                                  * won't proceed until we finish with the stripe.
5629                                  */
5630                                 int must_retry = 0;
5631                                 spin_lock_irq(&conf->device_lock);
5632                                 if (mddev->reshape_backwards
5633                                     ? logical_sector >= conf->reshape_progress
5634                                     : logical_sector < conf->reshape_progress)
5635                                         /* mismatch, need to try again */
5636                                         must_retry = 1;
5637                                 spin_unlock_irq(&conf->device_lock);
5638                                 if (must_retry) {
5639                                         raid5_release_stripe(sh);
5640                                         schedule();
5641                                         do_prepare = true;
5642                                         goto retry;
5643                                 }
5644                         }
5645                         if (read_seqcount_retry(&conf->gen_lock, seq)) {
5646                                 /* Might have got the wrong stripe_head
5647                                  * by accident
5648                                  */
5649                                 raid5_release_stripe(sh);
5650                                 goto retry;
5651                         }
5652
5653                         if (rw == WRITE &&
5654                             logical_sector >= mddev->suspend_lo &&
5655                             logical_sector < mddev->suspend_hi) {
5656                                 raid5_release_stripe(sh);
5657                                 /* As the suspend_* range is controlled by
5658                                  * userspace, we want an interruptible
5659                                  * wait.
5660                                  */
5661                                 flush_signals(current);
5662                                 prepare_to_wait(&conf->wait_for_overlap,
5663                                                 &w, TASK_INTERRUPTIBLE);
5664                                 if (logical_sector >= mddev->suspend_lo &&
5665                                     logical_sector < mddev->suspend_hi) {
5666                                         schedule();
5667                                         do_prepare = true;
5668                                 }
5669                                 goto retry;
5670                         }
5671
5672                         if (test_bit(STRIPE_EXPANDING, &sh->state) ||
5673                             !add_stripe_bio(sh, bi, dd_idx, rw, previous)) {
5674                                 /* Stripe is busy expanding or
5675                                  * add failed due to overlap.  Flush everything
5676                                  * and wait a while
5677                                  */
5678                                 md_wakeup_thread(mddev->thread);
5679                                 raid5_release_stripe(sh);
5680                                 schedule();
5681                                 do_prepare = true;
5682                                 goto retry;
5683                         }
5684                         if (do_flush) {
5685                                 set_bit(STRIPE_R5C_PREFLUSH, &sh->state);
5686                                 /* we only need flush for one stripe */
5687                                 do_flush = false;
5688                         }
5689
5690                         set_bit(STRIPE_HANDLE, &sh->state);
5691                         clear_bit(STRIPE_DELAYED, &sh->state);
5692                         if ((!sh->batch_head || sh == sh->batch_head) &&
5693                             (bi->bi_opf & REQ_SYNC) &&
5694                             !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5695                                 atomic_inc(&conf->preread_active_stripes);
5696                         release_stripe_plug(mddev, sh);
5697                 } else {
5698                         /* cannot get stripe for read-ahead, just give-up */
5699                         bi->bi_error = -EIO;
5700                         break;
5701                 }
5702         }
5703         finish_wait(&conf->wait_for_overlap, &w);
5704
5705         if (rw == WRITE)
5706                 md_write_end(mddev);
5707         bio_endio(bi);
5708 }
5709
5710 static sector_t raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks);
5711
5712 static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *skipped)
5713 {
5714         /* reshaping is quite different to recovery/resync so it is
5715          * handled quite separately ... here.
5716          *
5717          * On each call to sync_request, we gather one chunk worth of
5718          * destination stripes and flag them as expanding.
5719          * Then we find all the source stripes and request reads.
5720          * As the reads complete, handle_stripe will copy the data
5721          * into the destination stripe and release that stripe.
5722          */
5723         struct r5conf *conf = mddev->private;
5724         struct stripe_head *sh;
5725         sector_t first_sector, last_sector;
5726         int raid_disks = conf->previous_raid_disks;
5727         int data_disks = raid_disks - conf->max_degraded;
5728         int new_data_disks = conf->raid_disks - conf->max_degraded;
5729         int i;
5730         int dd_idx;
5731         sector_t writepos, readpos, safepos;
5732         sector_t stripe_addr;
5733         int reshape_sectors;
5734         struct list_head stripes;
5735         sector_t retn;
5736
5737         if (sector_nr == 0) {
5738                 /* If restarting in the middle, skip the initial sectors */
5739                 if (mddev->reshape_backwards &&
5740                     conf->reshape_progress < raid5_size(mddev, 0, 0)) {
5741                         sector_nr = raid5_size(mddev, 0, 0)
5742                                 - conf->reshape_progress;
5743                 } else if (mddev->reshape_backwards &&
5744                            conf->reshape_progress == MaxSector) {
5745                         /* shouldn't happen, but just in case, finish up.*/
5746                         sector_nr = MaxSector;
5747                 } else if (!mddev->reshape_backwards &&
5748                            conf->reshape_progress > 0)
5749                         sector_nr = conf->reshape_progress;
5750                 sector_div(sector_nr, new_data_disks);
5751                 if (sector_nr) {
5752                         mddev->curr_resync_completed = sector_nr;
5753                         sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5754                         *skipped = 1;
5755                         retn = sector_nr;
5756                         goto finish;
5757                 }
5758         }
5759
5760         /* We need to process a full chunk at a time.
5761          * If old and new chunk sizes differ, we need to process the
5762          * largest of these
5763          */
5764
5765         reshape_sectors = max(conf->chunk_sectors, conf->prev_chunk_sectors);
5766
5767         /* We update the metadata at least every 10 seconds, or when
5768          * the data about to be copied would over-write the source of
5769          * the data at the front of the range.  i.e. one new_stripe
5770          * along from reshape_progress new_maps to after where
5771          * reshape_safe old_maps to
5772          */
5773         writepos = conf->reshape_progress;
5774         sector_div(writepos, new_data_disks);
5775         readpos = conf->reshape_progress;
5776         sector_div(readpos, data_disks);
5777         safepos = conf->reshape_safe;
5778         sector_div(safepos, data_disks);
5779         if (mddev->reshape_backwards) {
5780                 BUG_ON(writepos < reshape_sectors);
5781                 writepos -= reshape_sectors;
5782                 readpos += reshape_sectors;
5783                 safepos += reshape_sectors;
5784         } else {
5785                 writepos += reshape_sectors;
5786                 /* readpos and safepos are worst-case calculations.
5787                  * A negative number is overly pessimistic, and causes
5788                  * obvious problems for unsigned storage.  So clip to 0.
5789                  */
5790                 readpos -= min_t(sector_t, reshape_sectors, readpos);
5791                 safepos -= min_t(sector_t, reshape_sectors, safepos);
5792         }
5793
5794         /* Having calculated the 'writepos' possibly use it
5795          * to set 'stripe_addr' which is where we will write to.
5796          */
5797         if (mddev->reshape_backwards) {
5798                 BUG_ON(conf->reshape_progress == 0);
5799                 stripe_addr = writepos;
5800                 BUG_ON((mddev->dev_sectors &
5801                         ~((sector_t)reshape_sectors - 1))
5802                        - reshape_sectors - stripe_addr
5803                        != sector_nr);
5804         } else {
5805                 BUG_ON(writepos != sector_nr + reshape_sectors);
5806                 stripe_addr = sector_nr;
5807         }
5808
5809         /* 'writepos' is the most advanced device address we might write.
5810          * 'readpos' is the least advanced device address we might read.
5811          * 'safepos' is the least address recorded in the metadata as having
5812          *     been reshaped.
5813          * If there is a min_offset_diff, these are adjusted either by
5814          * increasing the safepos/readpos if diff is negative, or
5815          * increasing writepos if diff is positive.
5816          * If 'readpos' is then behind 'writepos', there is no way that we can
5817          * ensure safety in the face of a crash - that must be done by userspace
5818          * making a backup of the data.  So in that case there is no particular
5819          * rush to update metadata.
5820          * Otherwise if 'safepos' is behind 'writepos', then we really need to
5821          * update the metadata to advance 'safepos' to match 'readpos' so that
5822          * we can be safe in the event of a crash.
5823          * So we insist on updating metadata if safepos is behind writepos and
5824          * readpos is beyond writepos.
5825          * In any case, update the metadata every 10 seconds.
5826          * Maybe that number should be configurable, but I'm not sure it is
5827          * worth it.... maybe it could be a multiple of safemode_delay???
5828          */
5829         if (conf->min_offset_diff < 0) {
5830                 safepos += -conf->min_offset_diff;
5831                 readpos += -conf->min_offset_diff;
5832         } else
5833                 writepos += conf->min_offset_diff;
5834
5835         if ((mddev->reshape_backwards
5836              ? (safepos > writepos && readpos < writepos)
5837              : (safepos < writepos && readpos > writepos)) ||
5838             time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
5839                 /* Cannot proceed until we've updated the superblock... */
5840                 wait_event(conf->wait_for_overlap,
5841                            atomic_read(&conf->reshape_stripes)==0
5842                            || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5843                 if (atomic_read(&conf->reshape_stripes) != 0)
5844                         return 0;
5845                 mddev->reshape_position = conf->reshape_progress;
5846                 mddev->curr_resync_completed = sector_nr;
5847                 conf->reshape_checkpoint = jiffies;
5848                 set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
5849                 md_wakeup_thread(mddev->thread);
5850                 wait_event(mddev->sb_wait, mddev->sb_flags == 0 ||
5851                            test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5852                 if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
5853                         return 0;
5854                 spin_lock_irq(&conf->device_lock);
5855                 conf->reshape_safe = mddev->reshape_position;
5856                 spin_unlock_irq(&conf->device_lock);
5857                 wake_up(&conf->wait_for_overlap);
5858                 sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5859         }
5860
5861         INIT_LIST_HEAD(&stripes);
5862         for (i = 0; i < reshape_sectors; i += STRIPE_SECTORS) {
5863                 int j;
5864                 int skipped_disk = 0;
5865                 sh = raid5_get_active_stripe(conf, stripe_addr+i, 0, 0, 1);
5866                 set_bit(STRIPE_EXPANDING, &sh->state);
5867                 atomic_inc(&conf->reshape_stripes);
5868                 /* If any of this stripe is beyond the end of the old
5869                  * array, then we need to zero those blocks
5870                  */
5871                 for (j=sh->disks; j--;) {
5872                         sector_t s;
5873                         if (j == sh->pd_idx)
5874                                 continue;
5875                         if (conf->level == 6 &&
5876                             j == sh->qd_idx)
5877                                 continue;
5878                         s = raid5_compute_blocknr(sh, j, 0);
5879                         if (s < raid5_size(mddev, 0, 0)) {
5880                                 skipped_disk = 1;
5881                                 continue;
5882                         }
5883                         memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
5884                         set_bit(R5_Expanded, &sh->dev[j].flags);
5885                         set_bit(R5_UPTODATE, &sh->dev[j].flags);
5886                 }
5887                 if (!skipped_disk) {
5888                         set_bit(STRIPE_EXPAND_READY, &sh->state);
5889                         set_bit(STRIPE_HANDLE, &sh->state);
5890                 }
5891                 list_add(&sh->lru, &stripes);
5892         }
5893         spin_lock_irq(&conf->device_lock);
5894         if (mddev->reshape_backwards)
5895                 conf->reshape_progress -= reshape_sectors * new_data_disks;
5896         else
5897                 conf->reshape_progress += reshape_sectors * new_data_disks;
5898         spin_unlock_irq(&conf->device_lock);
5899         /* Ok, those stripe are ready. We can start scheduling
5900          * reads on the source stripes.
5901          * The source stripes are determined by mapping the first and last
5902          * block on the destination stripes.
5903          */
5904         first_sector =
5905                 raid5_compute_sector(conf, stripe_addr*(new_data_disks),
5906                                      1, &dd_idx, NULL);
5907         last_sector =
5908                 raid5_compute_sector(conf, ((stripe_addr+reshape_sectors)
5909                                             * new_data_disks - 1),
5910                                      1, &dd_idx, NULL);
5911         if (last_sector >= mddev->dev_sectors)
5912                 last_sector = mddev->dev_sectors - 1;
5913         while (first_sector <= last_sector) {
5914                 sh = raid5_get_active_stripe(conf, first_sector, 1, 0, 1);
5915                 set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
5916                 set_bit(STRIPE_HANDLE, &sh->state);
5917                 raid5_release_stripe(sh);
5918                 first_sector += STRIPE_SECTORS;
5919         }
5920         /* Now that the sources are clearly marked, we can release
5921          * the destination stripes
5922          */
5923         while (!list_empty(&stripes)) {
5924                 sh = list_entry(stripes.next, struct stripe_head, lru);
5925                 list_del_init(&sh->lru);
5926                 raid5_release_stripe(sh);
5927         }
5928         /* If this takes us to the resync_max point where we have to pause,
5929          * then we need to write out the superblock.
5930          */
5931         sector_nr += reshape_sectors;
5932         retn = reshape_sectors;
5933 finish:
5934         if (mddev->curr_resync_completed > mddev->resync_max ||
5935             (sector_nr - mddev->curr_resync_completed) * 2
5936             >= mddev->resync_max - mddev->curr_resync_completed) {
5937                 /* Cannot proceed until we've updated the superblock... */
5938                 wait_event(conf->wait_for_overlap,
5939                            atomic_read(&conf->reshape_stripes) == 0
5940                            || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5941                 if (atomic_read(&conf->reshape_stripes) != 0)
5942                         goto ret;
5943                 mddev->reshape_position = conf->reshape_progress;
5944                 mddev->curr_resync_completed = sector_nr;
5945                 conf->reshape_checkpoint = jiffies;
5946                 set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
5947                 md_wakeup_thread(mddev->thread);
5948                 wait_event(mddev->sb_wait,
5949                            !test_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags)
5950                            || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5951                 if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
5952                         goto ret;
5953                 spin_lock_irq(&conf->device_lock);
5954                 conf->reshape_safe = mddev->reshape_position;
5955                 spin_unlock_irq(&conf->device_lock);
5956                 wake_up(&conf->wait_for_overlap);
5957                 sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5958         }
5959 ret:
5960         return retn;
5961 }
5962
5963 static inline sector_t raid5_sync_request(struct mddev *mddev, sector_t sector_nr,
5964                                           int *skipped)
5965 {
5966         struct r5conf *conf = mddev->private;
5967         struct stripe_head *sh;
5968         sector_t max_sector = mddev->dev_sectors;
5969         sector_t sync_blocks;
5970         int still_degraded = 0;
5971         int i;
5972
5973         if (sector_nr >= max_sector) {
5974                 /* just being told to finish up .. nothing much to do */
5975
5976                 if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
5977                         end_reshape(conf);
5978                         return 0;
5979                 }
5980
5981                 if (mddev->curr_resync < max_sector) /* aborted */
5982                         bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
5983                                         &sync_blocks, 1);
5984                 else /* completed sync */
5985                         conf->fullsync = 0;
5986                 bitmap_close_sync(mddev->bitmap);
5987
5988                 return 0;
5989         }
5990
5991         /* Allow raid5_quiesce to complete */
5992         wait_event(conf->wait_for_overlap, conf->quiesce != 2);
5993
5994         if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
5995                 return reshape_request(mddev, sector_nr, skipped);
5996
5997         /* No need to check resync_max as we never do more than one
5998          * stripe, and as resync_max will always be on a chunk boundary,
5999          * if the check in md_do_sync didn't fire, there is no chance
6000          * of overstepping resync_max here
6001          */
6002
6003         /* if there is too many failed drives and we are trying
6004          * to resync, then assert that we are finished, because there is
6005          * nothing we can do.
6006          */
6007         if (mddev->degraded >= conf->max_degraded &&
6008             test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
6009                 sector_t rv = mddev->dev_sectors - sector_nr;
6010                 *skipped = 1;
6011                 return rv;
6012         }
6013         if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
6014             !conf->fullsync &&
6015             !bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
6016             sync_blocks >= STRIPE_SECTORS) {
6017                 /* we can skip this block, and probably more */
6018                 sync_blocks /= STRIPE_SECTORS;
6019                 *skipped = 1;
6020                 return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
6021         }
6022
6023         bitmap_cond_end_sync(mddev->bitmap, sector_nr, false);
6024
6025         sh = raid5_get_active_stripe(conf, sector_nr, 0, 1, 0);
6026         if (sh == NULL) {
6027                 sh = raid5_get_active_stripe(conf, sector_nr, 0, 0, 0);
6028                 /* make sure we don't swamp the stripe cache if someone else
6029                  * is trying to get access
6030                  */
6031                 schedule_timeout_uninterruptible(1);
6032         }
6033         /* Need to check if array will still be degraded after recovery/resync
6034          * Note in case of > 1 drive failures it's possible we're rebuilding
6035          * one drive while leaving another faulty drive in array.
6036          */
6037         rcu_read_lock();
6038         for (i = 0; i < conf->raid_disks; i++) {
6039                 struct md_rdev *rdev = ACCESS_ONCE(conf->disks[i].rdev);
6040
6041                 if (rdev == NULL || test_bit(Faulty, &rdev->flags))
6042                         still_degraded = 1;
6043         }
6044         rcu_read_unlock();
6045
6046         bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
6047
6048         set_bit(STRIPE_SYNC_REQUESTED, &sh->state);
6049         set_bit(STRIPE_HANDLE, &sh->state);
6050
6051         raid5_release_stripe(sh);
6052
6053         return STRIPE_SECTORS;
6054 }
6055
6056 static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio,
6057                                unsigned int offset)
6058 {
6059         /* We may not be able to submit a whole bio at once as there
6060          * may not be enough stripe_heads available.
6061          * We cannot pre-allocate enough stripe_heads as we may need
6062          * more than exist in the cache (if we allow ever large chunks).
6063          * So we do one stripe head at a time and record in
6064          * ->bi_hw_segments how many have been done.
6065          *
6066          * We *know* that this entire raid_bio is in one chunk, so
6067          * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
6068          */
6069         struct stripe_head *sh;
6070         int dd_idx;
6071         sector_t sector, logical_sector, last_sector;
6072         int scnt = 0;
6073         int handled = 0;
6074
6075         logical_sector = raid_bio->bi_iter.bi_sector &
6076                 ~((sector_t)STRIPE_SECTORS-1);
6077         sector = raid5_compute_sector(conf, logical_sector,
6078                                       0, &dd_idx, NULL);
6079         last_sector = bio_end_sector(raid_bio);
6080
6081         for (; logical_sector < last_sector;
6082              logical_sector += STRIPE_SECTORS,
6083                      sector += STRIPE_SECTORS,
6084                      scnt++) {
6085
6086                 if (scnt < offset)
6087                         /* already done this stripe */
6088                         continue;
6089
6090                 sh = raid5_get_active_stripe(conf, sector, 0, 1, 1);
6091
6092                 if (!sh) {
6093                         /* failed to get a stripe - must wait */
6094                         conf->retry_read_aligned = raid_bio;
6095                         conf->retry_read_offset = scnt;
6096                         return handled;
6097                 }
6098
6099                 if (!add_stripe_bio(sh, raid_bio, dd_idx, 0, 0)) {
6100                         raid5_release_stripe(sh);
6101                         conf->retry_read_aligned = raid_bio;
6102                         conf->retry_read_offset = scnt;
6103                         return handled;
6104                 }
6105
6106                 set_bit(R5_ReadNoMerge, &sh->dev[dd_idx].flags);
6107                 handle_stripe(sh);
6108                 raid5_release_stripe(sh);
6109                 handled++;
6110         }
6111
6112         bio_endio(raid_bio);
6113
6114         if (atomic_dec_and_test(&conf->active_aligned_reads))
6115                 wake_up(&conf->wait_for_quiescent);
6116         return handled;
6117 }
6118
6119 static int handle_active_stripes(struct r5conf *conf, int group,
6120                                  struct r5worker *worker,
6121                                  struct list_head *temp_inactive_list)
6122 {
6123         struct stripe_head *batch[MAX_STRIPE_BATCH], *sh;
6124         int i, batch_size = 0, hash;
6125         bool release_inactive = false;
6126
6127         while (batch_size < MAX_STRIPE_BATCH &&
6128                         (sh = __get_priority_stripe(conf, group)) != NULL)
6129                 batch[batch_size++] = sh;
6130
6131         if (batch_size == 0) {
6132                 for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
6133                         if (!list_empty(temp_inactive_list + i))
6134                                 break;
6135                 if (i == NR_STRIPE_HASH_LOCKS) {
6136                         spin_unlock_irq(&conf->device_lock);
6137                         r5l_flush_stripe_to_raid(conf->log);
6138                         spin_lock_irq(&conf->device_lock);
6139                         return batch_size;
6140                 }
6141                 release_inactive = true;
6142         }
6143         spin_unlock_irq(&conf->device_lock);
6144
6145         release_inactive_stripe_list(conf, temp_inactive_list,
6146                                      NR_STRIPE_HASH_LOCKS);
6147
6148         r5l_flush_stripe_to_raid(conf->log);
6149         if (release_inactive) {
6150                 spin_lock_irq(&conf->device_lock);
6151                 return 0;
6152         }
6153
6154         for (i = 0; i < batch_size; i++)
6155                 handle_stripe(batch[i]);
6156         log_write_stripe_run(conf);
6157
6158         cond_resched();
6159
6160         spin_lock_irq(&conf->device_lock);
6161         for (i = 0; i < batch_size; i++) {
6162                 hash = batch[i]->hash_lock_index;
6163                 __release_stripe(conf, batch[i], &temp_inactive_list[hash]);
6164         }
6165         return batch_size;
6166 }
6167
6168 static void raid5_do_work(struct work_struct *work)
6169 {
6170         struct r5worker *worker = container_of(work, struct r5worker, work);
6171         struct r5worker_group *group = worker->group;
6172         struct r5conf *conf = group->conf;
6173         struct mddev *mddev = conf->mddev;
6174         int group_id = group - conf->worker_groups;
6175         int handled;
6176         struct blk_plug plug;
6177
6178         pr_debug("+++ raid5worker active\n");
6179
6180         blk_start_plug(&plug);
6181         handled = 0;
6182         spin_lock_irq(&conf->device_lock);
6183         while (1) {
6184                 int batch_size, released;
6185
6186                 released = release_stripe_list(conf, worker->temp_inactive_list);
6187
6188                 batch_size = handle_active_stripes(conf, group_id, worker,
6189                                                    worker->temp_inactive_list);
6190                 worker->working = false;
6191                 if (!batch_size && !released)
6192                         break;
6193                 handled += batch_size;
6194                 wait_event_lock_irq(mddev->sb_wait,
6195                         !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags),
6196                         conf->device_lock);
6197         }
6198         pr_debug("%d stripes handled\n", handled);
6199
6200         spin_unlock_irq(&conf->device_lock);
6201         blk_finish_plug(&plug);
6202
6203         pr_debug("--- raid5worker inactive\n");
6204 }
6205
6206 /*
6207  * This is our raid5 kernel thread.
6208  *
6209  * We scan the hash table for stripes which can be handled now.
6210  * During the scan, completed stripes are saved for us by the interrupt
6211  * handler, so that they will not have to wait for our next wakeup.
6212  */
6213 static void raid5d(struct md_thread *thread)
6214 {
6215         struct mddev *mddev = thread->mddev;
6216         struct r5conf *conf = mddev->private;
6217         int handled;
6218         struct blk_plug plug;
6219
6220         pr_debug("+++ raid5d active\n");
6221
6222         md_check_recovery(mddev);
6223
6224         blk_start_plug(&plug);
6225         handled = 0;
6226         spin_lock_irq(&conf->device_lock);
6227         while (1) {
6228                 struct bio *bio;
6229                 int batch_size, released;
6230                 unsigned int offset;
6231
6232                 released = release_stripe_list(conf, conf->temp_inactive_list);
6233                 if (released)
6234                         clear_bit(R5_DID_ALLOC, &conf->cache_state);
6235
6236                 if (
6237                     !list_empty(&conf->bitmap_list)) {
6238                         /* Now is a good time to flush some bitmap updates */
6239                         conf->seq_flush++;
6240                         spin_unlock_irq(&conf->device_lock);
6241                         bitmap_unplug(mddev->bitmap);
6242                         spin_lock_irq(&conf->device_lock);
6243                         conf->seq_write = conf->seq_flush;
6244                         activate_bit_delay(conf, conf->temp_inactive_list);
6245                 }
6246                 raid5_activate_delayed(conf);
6247
6248                 while ((bio = remove_bio_from_retry(conf, &offset))) {
6249                         int ok;
6250                         spin_unlock_irq(&conf->device_lock);
6251                         ok = retry_aligned_read(conf, bio, offset);
6252                         spin_lock_irq(&conf->device_lock);
6253                         if (!ok)
6254                                 break;
6255                         handled++;
6256                 }
6257
6258                 batch_size = handle_active_stripes(conf, ANY_GROUP, NULL,
6259                                                    conf->temp_inactive_list);
6260                 if (!batch_size && !released)
6261                         break;
6262                 handled += batch_size;
6263
6264                 if (mddev->sb_flags & ~(1 << MD_SB_CHANGE_PENDING)) {
6265                         spin_unlock_irq(&conf->device_lock);
6266                         md_check_recovery(mddev);
6267                         spin_lock_irq(&conf->device_lock);
6268                 }
6269         }
6270         pr_debug("%d stripes handled\n", handled);
6271
6272         spin_unlock_irq(&conf->device_lock);
6273         if (test_and_clear_bit(R5_ALLOC_MORE, &conf->cache_state) &&
6274             mutex_trylock(&conf->cache_size_mutex)) {
6275                 grow_one_stripe(conf, __GFP_NOWARN);
6276                 /* Set flag even if allocation failed.  This helps
6277                  * slow down allocation requests when mem is short
6278                  */
6279                 set_bit(R5_DID_ALLOC, &conf->cache_state);
6280                 mutex_unlock(&conf->cache_size_mutex);
6281         }
6282
6283         flush_deferred_bios(conf);
6284
6285         r5l_flush_stripe_to_raid(conf->log);
6286
6287         async_tx_issue_pending_all();
6288         blk_finish_plug(&plug);
6289
6290         pr_debug("--- raid5d inactive\n");
6291 }
6292
6293 static ssize_t
6294 raid5_show_stripe_cache_size(struct mddev *mddev, char *page)
6295 {
6296         struct r5conf *conf;
6297         int ret = 0;
6298         spin_lock(&mddev->lock);
6299         conf = mddev->private;
6300         if (conf)
6301                 ret = sprintf(page, "%d\n", conf->min_nr_stripes);
6302         spin_unlock(&mddev->lock);
6303         return ret;
6304 }
6305
6306 int
6307 raid5_set_cache_size(struct mddev *mddev, int size)
6308 {
6309         struct r5conf *conf = mddev->private;
6310         int err;
6311
6312         if (size <= 16 || size > 32768)
6313                 return -EINVAL;
6314
6315         conf->min_nr_stripes = size;
6316         mutex_lock(&conf->cache_size_mutex);
6317         while (size < conf->max_nr_stripes &&
6318                drop_one_stripe(conf))
6319                 ;
6320         mutex_unlock(&conf->cache_size_mutex);
6321
6322
6323         err = md_allow_write(mddev);
6324         if (err)
6325                 return err;
6326
6327         mutex_lock(&conf->cache_size_mutex);
6328         while (size > conf->max_nr_stripes)
6329                 if (!grow_one_stripe(conf, GFP_KERNEL))
6330                         break;
6331         mutex_unlock(&conf->cache_size_mutex);
6332
6333         return 0;
6334 }
6335 EXPORT_SYMBOL(raid5_set_cache_size);
6336
6337 static ssize_t
6338 raid5_store_stripe_cache_size(struct mddev *mddev, const char *page, size_t len)
6339 {
6340         struct r5conf *conf;
6341         unsigned long new;
6342         int err;
6343
6344         if (len >= PAGE_SIZE)
6345                 return -EINVAL;
6346         if (kstrtoul(page, 10, &new))
6347                 return -EINVAL;
6348         err = mddev_lock(mddev);
6349         if (err)
6350                 return err;
6351         conf = mddev->private;
6352         if (!conf)
6353                 err = -ENODEV;
6354         else
6355                 err = raid5_set_cache_size(mddev, new);
6356         mddev_unlock(mddev);
6357
6358         return err ?: len;
6359 }
6360
6361 static struct md_sysfs_entry
6362 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
6363                                 raid5_show_stripe_cache_size,
6364                                 raid5_store_stripe_cache_size);
6365
6366 static ssize_t
6367 raid5_show_rmw_level(struct mddev  *mddev, char *page)
6368 {
6369         struct r5conf *conf = mddev->private;
6370         if (conf)
6371                 return sprintf(page, "%d\n", conf->rmw_level);
6372         else
6373                 return 0;
6374 }
6375
6376 static ssize_t
6377 raid5_store_rmw_level(struct mddev  *mddev, const char *page, size_t len)
6378 {
6379         struct r5conf *conf = mddev->private;
6380         unsigned long new;
6381
6382         if (!conf)
6383                 return -ENODEV;
6384
6385         if (len >= PAGE_SIZE)
6386                 return -EINVAL;
6387
6388         if (kstrtoul(page, 10, &new))
6389                 return -EINVAL;
6390
6391         if (new != PARITY_DISABLE_RMW && !raid6_call.xor_syndrome)
6392                 return -EINVAL;
6393
6394         if (new != PARITY_DISABLE_RMW &&
6395             new != PARITY_ENABLE_RMW &&
6396             new != PARITY_PREFER_RMW)
6397                 return -EINVAL;
6398
6399         conf->rmw_level = new;
6400         return len;
6401 }
6402
6403 static struct md_sysfs_entry
6404 raid5_rmw_level = __ATTR(rmw_level, S_IRUGO | S_IWUSR,
6405                          raid5_show_rmw_level,
6406                          raid5_store_rmw_level);
6407
6408
6409 static ssize_t
6410 raid5_show_preread_threshold(struct mddev *mddev, char *page)
6411 {
6412         struct r5conf *conf;
6413         int ret = 0;
6414         spin_lock(&mddev->lock);
6415         conf = mddev->private;
6416         if (conf)
6417                 ret = sprintf(page, "%d\n", conf->bypass_threshold);
6418         spin_unlock(&mddev->lock);
6419         return ret;
6420 }
6421
6422 static ssize_t
6423 raid5_store_preread_threshold(struct mddev *mddev, const char *page, size_t len)
6424 {
6425         struct r5conf *conf;
6426         unsigned long new;
6427         int err;
6428
6429         if (len >= PAGE_SIZE)
6430                 return -EINVAL;
6431         if (kstrtoul(page, 10, &new))
6432                 return -EINVAL;
6433
6434         err = mddev_lock(mddev);
6435         if (err)
6436                 return err;
6437         conf = mddev->private;
6438         if (!conf)
6439                 err = -ENODEV;
6440         else if (new > conf->min_nr_stripes)
6441                 err = -EINVAL;
6442         else
6443                 conf->bypass_threshold = new;
6444         mddev_unlock(mddev);
6445         return err ?: len;
6446 }
6447
6448 static struct md_sysfs_entry
6449 raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold,
6450                                         S_IRUGO | S_IWUSR,
6451                                         raid5_show_preread_threshold,
6452                                         raid5_store_preread_threshold);
6453
6454 static ssize_t
6455 raid5_show_skip_copy(struct mddev *mddev, char *page)
6456 {
6457         struct r5conf *conf;
6458         int ret = 0;
6459         spin_lock(&mddev->lock);
6460         conf = mddev->private;
6461         if (conf)
6462                 ret = sprintf(page, "%d\n", conf->skip_copy);
6463         spin_unlock(&mddev->lock);
6464         return ret;
6465 }
6466
6467 static ssize_t
6468 raid5_store_skip_copy(struct mddev *mddev, const char *page, size_t len)
6469 {
6470         struct r5conf *conf;
6471         unsigned long new;
6472         int err;
6473
6474         if (len >= PAGE_SIZE)
6475                 return -EINVAL;
6476         if (kstrtoul(page, 10, &new))
6477                 return -EINVAL;
6478         new = !!new;
6479
6480         err = mddev_lock(mddev);
6481         if (err)
6482                 return err;
6483         conf = mddev->private;
6484         if (!conf)
6485                 err = -ENODEV;
6486         else if (new != conf->skip_copy) {
6487                 mddev_suspend(mddev);
6488                 conf->skip_copy = new;
6489                 if (new)
6490                         mddev->queue->backing_dev_info->capabilities |=
6491                                 BDI_CAP_STABLE_WRITES;
6492                 else
6493                         mddev->queue->backing_dev_info->capabilities &=
6494                                 ~BDI_CAP_STABLE_WRITES;
6495                 mddev_resume(mddev);
6496         }
6497         mddev_unlock(mddev);
6498         return err ?: len;
6499 }
6500
6501 static struct md_sysfs_entry
6502 raid5_skip_copy = __ATTR(skip_copy, S_IRUGO | S_IWUSR,
6503                                         raid5_show_skip_copy,
6504                                         raid5_store_skip_copy);
6505
6506 static ssize_t
6507 stripe_cache_active_show(struct mddev *mddev, char *page)
6508 {
6509         struct r5conf *conf = mddev->private;
6510         if (conf)
6511                 return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
6512         else
6513                 return 0;
6514 }
6515
6516 static struct md_sysfs_entry
6517 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
6518
6519 static ssize_t
6520 raid5_show_group_thread_cnt(struct mddev *mddev, char *page)
6521 {
6522         struct r5conf *conf;
6523         int ret = 0;
6524         spin_lock(&mddev->lock);
6525         conf = mddev->private;
6526         if (conf)
6527                 ret = sprintf(page, "%d\n", conf->worker_cnt_per_group);
6528         spin_unlock(&mddev->lock);
6529         return ret;
6530 }
6531
6532 static int alloc_thread_groups(struct r5conf *conf, int cnt,
6533                                int *group_cnt,
6534                                int *worker_cnt_per_group,
6535                                struct r5worker_group **worker_groups);
6536 static ssize_t
6537 raid5_store_group_thread_cnt(struct mddev *mddev, const char *page, size_t len)
6538 {
6539         struct r5conf *conf;
6540         unsigned long new;
6541         int err;
6542         struct r5worker_group *new_groups, *old_groups;
6543         int group_cnt, worker_cnt_per_group;
6544
6545         if (len >= PAGE_SIZE)
6546                 return -EINVAL;
6547         if (kstrtoul(page, 10, &new))
6548                 return -EINVAL;
6549
6550         err = mddev_lock(mddev);
6551         if (err)
6552                 return err;
6553         conf = mddev->private;
6554         if (!conf)
6555                 err = -ENODEV;
6556         else if (new != conf->worker_cnt_per_group) {
6557                 mddev_suspend(mddev);
6558
6559                 old_groups = conf->worker_groups;
6560                 if (old_groups)
6561                         flush_workqueue(raid5_wq);
6562
6563                 err = alloc_thread_groups(conf, new,
6564                                           &group_cnt, &worker_cnt_per_group,
6565                                           &new_groups);
6566                 if (!err) {
6567                         spin_lock_irq(&conf->device_lock);
6568                         conf->group_cnt = group_cnt;
6569                         conf->worker_cnt_per_group = worker_cnt_per_group;
6570                         conf->worker_groups = new_groups;
6571                         spin_unlock_irq(&conf->device_lock);
6572
6573                         if (old_groups)
6574                                 kfree(old_groups[0].workers);
6575                         kfree(old_groups);
6576                 }
6577                 mddev_resume(mddev);
6578         }
6579         mddev_unlock(mddev);
6580
6581         return err ?: len;
6582 }
6583
6584 static struct md_sysfs_entry
6585 raid5_group_thread_cnt = __ATTR(group_thread_cnt, S_IRUGO | S_IWUSR,
6586                                 raid5_show_group_thread_cnt,
6587                                 raid5_store_group_thread_cnt);
6588
6589 static struct attribute *raid5_attrs[] =  {
6590         &raid5_stripecache_size.attr,
6591         &raid5_stripecache_active.attr,
6592         &raid5_preread_bypass_threshold.attr,
6593         &raid5_group_thread_cnt.attr,
6594         &raid5_skip_copy.attr,
6595         &raid5_rmw_level.attr,
6596         &r5c_journal_mode.attr,
6597         NULL,
6598 };
6599 static struct attribute_group raid5_attrs_group = {
6600         .name = NULL,
6601         .attrs = raid5_attrs,
6602 };
6603
6604 static int alloc_thread_groups(struct r5conf *conf, int cnt,
6605                                int *group_cnt,
6606                                int *worker_cnt_per_group,
6607                                struct r5worker_group **worker_groups)
6608 {
6609         int i, j, k;
6610         ssize_t size;
6611         struct r5worker *workers;
6612
6613         *worker_cnt_per_group = cnt;
6614         if (cnt == 0) {
6615                 *group_cnt = 0;
6616                 *worker_groups = NULL;
6617                 return 0;
6618         }
6619         *group_cnt = num_possible_nodes();
6620         size = sizeof(struct r5worker) * cnt;
6621         workers = kzalloc(size * *group_cnt, GFP_NOIO);
6622         *worker_groups = kzalloc(sizeof(struct r5worker_group) *
6623                                 *group_cnt, GFP_NOIO);
6624         if (!*worker_groups || !workers) {
6625                 kfree(workers);
6626                 kfree(*worker_groups);
6627                 return -ENOMEM;
6628         }
6629
6630         for (i = 0; i < *group_cnt; i++) {
6631                 struct r5worker_group *group;
6632
6633                 group = &(*worker_groups)[i];
6634                 INIT_LIST_HEAD(&group->handle_list);
6635                 INIT_LIST_HEAD(&group->loprio_list);
6636                 group->conf = conf;
6637                 group->workers = workers + i * cnt;
6638
6639                 for (j = 0; j < cnt; j++) {
6640                         struct r5worker *worker = group->workers + j;
6641                         worker->group = group;
6642                         INIT_WORK(&worker->work, raid5_do_work);
6643
6644                         for (k = 0; k < NR_STRIPE_HASH_LOCKS; k++)
6645                                 INIT_LIST_HEAD(worker->temp_inactive_list + k);
6646                 }
6647         }
6648
6649         return 0;
6650 }
6651
6652 static void free_thread_groups(struct r5conf *conf)
6653 {
6654         if (conf->worker_groups)
6655                 kfree(conf->worker_groups[0].workers);
6656         kfree(conf->worker_groups);
6657         conf->worker_groups = NULL;
6658 }
6659
6660 static sector_t
6661 raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks)
6662 {
6663         struct r5conf *conf = mddev->private;
6664
6665         if (!sectors)
6666                 sectors = mddev->dev_sectors;
6667         if (!raid_disks)
6668                 /* size is defined by the smallest of previous and new size */
6669                 raid_disks = min(conf->raid_disks, conf->previous_raid_disks);
6670
6671         sectors &= ~((sector_t)conf->chunk_sectors - 1);
6672         sectors &= ~((sector_t)conf->prev_chunk_sectors - 1);
6673         return sectors * (raid_disks - conf->max_degraded);
6674 }
6675
6676 static void free_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
6677 {
6678         safe_put_page(percpu->spare_page);
6679         if (percpu->scribble)
6680                 flex_array_free(percpu->scribble);
6681         percpu->spare_page = NULL;
6682         percpu->scribble = NULL;
6683 }
6684
6685 static int alloc_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
6686 {
6687         if (conf->level == 6 && !percpu->spare_page)
6688                 percpu->spare_page = alloc_page(GFP_KERNEL);
6689         if (!percpu->scribble)
6690                 percpu->scribble = scribble_alloc(max(conf->raid_disks,
6691                                                       conf->previous_raid_disks),
6692                                                   max(conf->chunk_sectors,
6693                                                       conf->prev_chunk_sectors)
6694                                                    / STRIPE_SECTORS,
6695                                                   GFP_KERNEL);
6696
6697         if (!percpu->scribble || (conf->level == 6 && !percpu->spare_page)) {
6698                 free_scratch_buffer(conf, percpu);
6699                 return -ENOMEM;
6700         }
6701
6702         return 0;
6703 }
6704
6705 static int raid456_cpu_dead(unsigned int cpu, struct hlist_node *node)
6706 {
6707         struct r5conf *conf = hlist_entry_safe(node, struct r5conf, node);
6708
6709         free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
6710         return 0;
6711 }
6712
6713 static void raid5_free_percpu(struct r5conf *conf)
6714 {
6715         if (!conf->percpu)
6716                 return;
6717
6718         cpuhp_state_remove_instance(CPUHP_MD_RAID5_PREPARE, &conf->node);
6719         free_percpu(conf->percpu);
6720 }
6721
6722 static void free_conf(struct r5conf *conf)
6723 {
6724         int i;
6725
6726         log_exit(conf);
6727
6728         if (conf->shrinker.nr_deferred)
6729                 unregister_shrinker(&conf->shrinker);
6730
6731         free_thread_groups(conf);
6732         shrink_stripes(conf);
6733         raid5_free_percpu(conf);
6734         for (i = 0; i < conf->pool_size; i++)
6735                 if (conf->disks[i].extra_page)
6736                         put_page(conf->disks[i].extra_page);
6737         kfree(conf->disks);
6738         kfree(conf->stripe_hashtbl);
6739         kfree(conf->pending_data);
6740         kfree(conf);
6741 }
6742
6743 static int raid456_cpu_up_prepare(unsigned int cpu, struct hlist_node *node)
6744 {
6745         struct r5conf *conf = hlist_entry_safe(node, struct r5conf, node);
6746         struct raid5_percpu *percpu = per_cpu_ptr(conf->percpu, cpu);
6747
6748         if (alloc_scratch_buffer(conf, percpu)) {
6749                 pr_warn("%s: failed memory allocation for cpu%u\n",
6750                         __func__, cpu);
6751                 return -ENOMEM;
6752         }
6753         return 0;
6754 }
6755
6756 static int raid5_alloc_percpu(struct r5conf *conf)
6757 {
6758         int err = 0;
6759
6760         conf->percpu = alloc_percpu(struct raid5_percpu);
6761         if (!conf->percpu)
6762                 return -ENOMEM;
6763
6764         err = cpuhp_state_add_instance(CPUHP_MD_RAID5_PREPARE, &conf->node);
6765         if (!err) {
6766                 conf->scribble_disks = max(conf->raid_disks,
6767                         conf->previous_raid_disks);
6768                 conf->scribble_sectors = max(conf->chunk_sectors,
6769                         conf->prev_chunk_sectors);
6770         }
6771         return err;
6772 }
6773
6774 static unsigned long raid5_cache_scan(struct shrinker *shrink,
6775                                       struct shrink_control *sc)
6776 {
6777         struct r5conf *conf = container_of(shrink, struct r5conf, shrinker);
6778         unsigned long ret = SHRINK_STOP;
6779
6780         if (mutex_trylock(&conf->cache_size_mutex)) {
6781                 ret= 0;
6782                 while (ret < sc->nr_to_scan &&
6783                        conf->max_nr_stripes > conf->min_nr_stripes) {
6784                         if (drop_one_stripe(conf) == 0) {
6785                                 ret = SHRINK_STOP;
6786                                 break;
6787                         }
6788                         ret++;
6789                 }
6790                 mutex_unlock(&conf->cache_size_mutex);
6791         }
6792         return ret;
6793 }
6794
6795 static unsigned long raid5_cache_count(struct shrinker *shrink,
6796                                        struct shrink_control *sc)
6797 {
6798         struct r5conf *conf = container_of(shrink, struct r5conf, shrinker);
6799
6800         if (conf->max_nr_stripes < conf->min_nr_stripes)
6801                 /* unlikely, but not impossible */
6802                 return 0;
6803         return conf->max_nr_stripes - conf->min_nr_stripes;
6804 }
6805
6806 static struct r5conf *setup_conf(struct mddev *mddev)
6807 {
6808         struct r5conf *conf;
6809         int raid_disk, memory, max_disks;
6810         struct md_rdev *rdev;
6811         struct disk_info *disk;
6812         char pers_name[6];
6813         int i;
6814         int group_cnt, worker_cnt_per_group;
6815         struct r5worker_group *new_group;
6816
6817         if (mddev->new_level != 5
6818             && mddev->new_level != 4
6819             && mddev->new_level != 6) {
6820                 pr_warn("md/raid:%s: raid level not set to 4/5/6 (%d)\n",
6821                         mdname(mddev), mddev->new_level);
6822                 return ERR_PTR(-EIO);
6823         }
6824         if ((mddev->new_level == 5
6825              && !algorithm_valid_raid5(mddev->new_layout)) ||
6826             (mddev->new_level == 6
6827              && !algorithm_valid_raid6(mddev->new_layout))) {
6828                 pr_warn("md/raid:%s: layout %d not supported\n",
6829                         mdname(mddev), mddev->new_layout);
6830                 return ERR_PTR(-EIO);
6831         }
6832         if (mddev->new_level == 6 && mddev->raid_disks < 4) {
6833                 pr_warn("md/raid:%s: not enough configured devices (%d, minimum 4)\n",
6834                         mdname(mddev), mddev->raid_disks);
6835                 return ERR_PTR(-EINVAL);
6836         }
6837
6838         if (!mddev->new_chunk_sectors ||
6839             (mddev->new_chunk_sectors << 9) % PAGE_SIZE ||
6840             !is_power_of_2(mddev->new_chunk_sectors)) {
6841                 pr_warn("md/raid:%s: invalid chunk size %d\n",
6842                         mdname(mddev), mddev->new_chunk_sectors << 9);
6843                 return ERR_PTR(-EINVAL);
6844         }
6845
6846         conf = kzalloc(sizeof(struct r5conf), GFP_KERNEL);
6847         if (conf == NULL)
6848                 goto abort;
6849         INIT_LIST_HEAD(&conf->free_list);
6850         INIT_LIST_HEAD(&conf->pending_list);
6851         conf->pending_data = kzalloc(sizeof(struct r5pending_data) *
6852                 PENDING_IO_MAX, GFP_KERNEL);
6853         if (!conf->pending_data)
6854                 goto abort;
6855         for (i = 0; i < PENDING_IO_MAX; i++)
6856                 list_add(&conf->pending_data[i].sibling, &conf->free_list);
6857         /* Don't enable multi-threading by default*/
6858         if (!alloc_thread_groups(conf, 0, &group_cnt, &worker_cnt_per_group,
6859                                  &new_group)) {
6860                 conf->group_cnt = group_cnt;
6861                 conf->worker_cnt_per_group = worker_cnt_per_group;
6862                 conf->worker_groups = new_group;
6863         } else
6864                 goto abort;
6865         spin_lock_init(&conf->device_lock);
6866         seqcount_init(&conf->gen_lock);
6867         mutex_init(&conf->cache_size_mutex);
6868         init_waitqueue_head(&conf->wait_for_quiescent);
6869         init_waitqueue_head(&conf->wait_for_stripe);
6870         init_waitqueue_head(&conf->wait_for_overlap);
6871         INIT_LIST_HEAD(&conf->handle_list);
6872         INIT_LIST_HEAD(&conf->loprio_list);
6873         INIT_LIST_HEAD(&conf->hold_list);
6874         INIT_LIST_HEAD(&conf->delayed_list);
6875         INIT_LIST_HEAD(&conf->bitmap_list);
6876         init_llist_head(&conf->released_stripes);
6877         atomic_set(&conf->active_stripes, 0);
6878         atomic_set(&conf->preread_active_stripes, 0);
6879         atomic_set(&conf->active_aligned_reads, 0);
6880         spin_lock_init(&conf->pending_bios_lock);
6881         conf->batch_bio_dispatch = true;
6882         rdev_for_each(rdev, mddev) {
6883                 if (test_bit(Journal, &rdev->flags))
6884                         continue;
6885                 if (blk_queue_nonrot(bdev_get_queue(rdev->bdev))) {
6886                         conf->batch_bio_dispatch = false;
6887                         break;
6888                 }
6889         }
6890
6891         conf->bypass_threshold = BYPASS_THRESHOLD;
6892         conf->recovery_disabled = mddev->recovery_disabled - 1;
6893
6894         conf->raid_disks = mddev->raid_disks;
6895         if (mddev->reshape_position == MaxSector)
6896                 conf->previous_raid_disks = mddev->raid_disks;
6897         else
6898                 conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
6899         max_disks = max(conf->raid_disks, conf->previous_raid_disks);
6900
6901         conf->disks = kzalloc(max_disks * sizeof(struct disk_info),
6902                               GFP_KERNEL);
6903
6904         if (!conf->disks)
6905                 goto abort;
6906
6907         for (i = 0; i < max_disks; i++) {
6908                 conf->disks[i].extra_page = alloc_page(GFP_KERNEL);
6909                 if (!conf->disks[i].extra_page)
6910                         goto abort;
6911         }
6912
6913         conf->mddev = mddev;
6914
6915         if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
6916                 goto abort;
6917
6918         /* We init hash_locks[0] separately to that it can be used
6919          * as the reference lock in the spin_lock_nest_lock() call
6920          * in lock_all_device_hash_locks_irq in order to convince
6921          * lockdep that we know what we are doing.
6922          */
6923         spin_lock_init(conf->hash_locks);
6924         for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
6925                 spin_lock_init(conf->hash_locks + i);
6926
6927         for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
6928                 INIT_LIST_HEAD(conf->inactive_list + i);
6929
6930         for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
6931                 INIT_LIST_HEAD(conf->temp_inactive_list + i);
6932
6933         atomic_set(&conf->r5c_cached_full_stripes, 0);
6934         INIT_LIST_HEAD(&conf->r5c_full_stripe_list);
6935         atomic_set(&conf->r5c_cached_partial_stripes, 0);
6936         INIT_LIST_HEAD(&conf->r5c_partial_stripe_list);
6937         atomic_set(&conf->r5c_flushing_full_stripes, 0);
6938         atomic_set(&conf->r5c_flushing_partial_stripes, 0);
6939
6940         conf->level = mddev->new_level;
6941         conf->chunk_sectors = mddev->new_chunk_sectors;
6942         if (raid5_alloc_percpu(conf) != 0)
6943                 goto abort;
6944
6945         pr_debug("raid456: run(%s) called.\n", mdname(mddev));
6946
6947         rdev_for_each(rdev, mddev) {
6948                 raid_disk = rdev->raid_disk;
6949                 if (raid_disk >= max_disks
6950                     || raid_disk < 0 || test_bit(Journal, &rdev->flags))
6951                         continue;
6952                 disk = conf->disks + raid_disk;
6953
6954                 if (test_bit(Replacement, &rdev->flags)) {
6955                         if (disk->replacement)
6956                                 goto abort;
6957                         disk->replacement = rdev;
6958                 } else {
6959                         if (disk->rdev)
6960                                 goto abort;
6961                         disk->rdev = rdev;
6962                 }
6963
6964                 if (test_bit(In_sync, &rdev->flags)) {
6965                         char b[BDEVNAME_SIZE];
6966                         pr_info("md/raid:%s: device %s operational as raid disk %d\n",
6967                                 mdname(mddev), bdevname(rdev->bdev, b), raid_disk);
6968                 } else if (rdev->saved_raid_disk != raid_disk)
6969                         /* Cannot rely on bitmap to complete recovery */
6970                         conf->fullsync = 1;
6971         }
6972
6973         conf->level = mddev->new_level;
6974         if (conf->level == 6) {
6975                 conf->max_degraded = 2;
6976                 if (raid6_call.xor_syndrome)
6977                         conf->rmw_level = PARITY_ENABLE_RMW;
6978                 else
6979                         conf->rmw_level = PARITY_DISABLE_RMW;
6980         } else {
6981                 conf->max_degraded = 1;
6982                 conf->rmw_level = PARITY_ENABLE_RMW;
6983         }
6984         conf->algorithm = mddev->new_layout;
6985         conf->reshape_progress = mddev->reshape_position;
6986         if (conf->reshape_progress != MaxSector) {
6987                 conf->prev_chunk_sectors = mddev->chunk_sectors;
6988                 conf->prev_algo = mddev->layout;
6989         } else {
6990                 conf->prev_chunk_sectors = conf->chunk_sectors;
6991                 conf->prev_algo = conf->algorithm;
6992         }
6993
6994         conf->min_nr_stripes = NR_STRIPES;
6995         if (mddev->reshape_position != MaxSector) {
6996                 int stripes = max_t(int,
6997                         ((mddev->chunk_sectors << 9) / STRIPE_SIZE) * 4,
6998                         ((mddev->new_chunk_sectors << 9) / STRIPE_SIZE) * 4);
6999                 conf->min_nr_stripes = max(NR_STRIPES, stripes);
7000                 if (conf->min_nr_stripes != NR_STRIPES)
7001                         pr_info("md/raid:%s: force stripe size %d for reshape\n",
7002                                 mdname(mddev), conf->min_nr_stripes);
7003         }
7004         memory = conf->min_nr_stripes * (sizeof(struct stripe_head) +
7005                  max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
7006         atomic_set(&conf->empty_inactive_list_nr, NR_STRIPE_HASH_LOCKS);
7007         if (grow_stripes(conf, conf->min_nr_stripes)) {
7008                 pr_warn("md/raid:%s: couldn't allocate %dkB for buffers\n",
7009                         mdname(mddev), memory);
7010                 goto abort;
7011         } else
7012                 pr_debug("md/raid:%s: allocated %dkB\n", mdname(mddev), memory);
7013         /*
7014          * Losing a stripe head costs more than the time to refill it,
7015          * it reduces the queue depth and so can hurt throughput.
7016          * So set it rather large, scaled by number of devices.
7017          */
7018         conf->shrinker.seeks = DEFAULT_SEEKS * conf->raid_disks * 4;
7019         conf->shrinker.scan_objects = raid5_cache_scan;
7020         conf->shrinker.count_objects = raid5_cache_count;
7021         conf->shrinker.batch = 128;
7022         conf->shrinker.flags = 0;
7023         if (register_shrinker(&conf->shrinker)) {
7024                 pr_warn("md/raid:%s: couldn't register shrinker.\n",
7025                         mdname(mddev));
7026                 goto abort;
7027         }
7028
7029         sprintf(pers_name, "raid%d", mddev->new_level);
7030         conf->thread = md_register_thread(raid5d, mddev, pers_name);
7031         if (!conf->thread) {
7032                 pr_warn("md/raid:%s: couldn't allocate thread.\n",
7033                         mdname(mddev));
7034                 goto abort;
7035         }
7036
7037         return conf;
7038
7039  abort:
7040         if (conf) {
7041                 free_conf(conf);
7042                 return ERR_PTR(-EIO);
7043         } else
7044                 return ERR_PTR(-ENOMEM);
7045 }
7046
7047 static int only_parity(int raid_disk, int algo, int raid_disks, int max_degraded)
7048 {
7049         switch (algo) {
7050         case ALGORITHM_PARITY_0:
7051                 if (raid_disk < max_degraded)
7052                         return 1;
7053                 break;
7054         case ALGORITHM_PARITY_N:
7055                 if (raid_disk >= raid_disks - max_degraded)
7056                         return 1;
7057                 break;
7058         case ALGORITHM_PARITY_0_6:
7059                 if (raid_disk == 0 ||
7060                     raid_disk == raid_disks - 1)
7061                         return 1;
7062                 break;
7063         case ALGORITHM_LEFT_ASYMMETRIC_6:
7064         case ALGORITHM_RIGHT_ASYMMETRIC_6:
7065         case ALGORITHM_LEFT_SYMMETRIC_6:
7066         case ALGORITHM_RIGHT_SYMMETRIC_6:
7067                 if (raid_disk == raid_disks - 1)
7068                         return 1;
7069         }
7070         return 0;
7071 }
7072
7073 static int raid5_run(struct mddev *mddev)
7074 {
7075         struct r5conf *conf;
7076         int working_disks = 0;
7077         int dirty_parity_disks = 0;
7078         struct md_rdev *rdev;
7079         struct md_rdev *journal_dev = NULL;
7080         sector_t reshape_offset = 0;
7081         int i;
7082         long long min_offset_diff = 0;
7083         int first = 1;
7084
7085         if (mddev->recovery_cp != MaxSector)
7086                 pr_notice("md/raid:%s: not clean -- starting background reconstruction\n",
7087                           mdname(mddev));
7088
7089         rdev_for_each(rdev, mddev) {
7090                 long long diff;
7091
7092                 if (test_bit(Journal, &rdev->flags)) {
7093                         journal_dev = rdev;
7094                         continue;
7095                 }
7096                 if (rdev->raid_disk < 0)
7097                         continue;
7098                 diff = (rdev->new_data_offset - rdev->data_offset);
7099                 if (first) {
7100                         min_offset_diff = diff;
7101                         first = 0;
7102                 } else if (mddev->reshape_backwards &&
7103                          diff < min_offset_diff)
7104                         min_offset_diff = diff;
7105                 else if (!mddev->reshape_backwards &&
7106                          diff > min_offset_diff)
7107                         min_offset_diff = diff;
7108         }
7109
7110         if (mddev->reshape_position != MaxSector) {
7111                 /* Check that we can continue the reshape.
7112                  * Difficulties arise if the stripe we would write to
7113                  * next is at or after the stripe we would read from next.
7114                  * For a reshape that changes the number of devices, this
7115                  * is only possible for a very short time, and mdadm makes
7116                  * sure that time appears to have past before assembling
7117                  * the array.  So we fail if that time hasn't passed.
7118                  * For a reshape that keeps the number of devices the same
7119                  * mdadm must be monitoring the reshape can keeping the
7120                  * critical areas read-only and backed up.  It will start
7121                  * the array in read-only mode, so we check for that.
7122                  */
7123                 sector_t here_new, here_old;
7124                 int old_disks;
7125                 int max_degraded = (mddev->level == 6 ? 2 : 1);
7126                 int chunk_sectors;
7127                 int new_data_disks;
7128
7129                 if (journal_dev) {
7130                         pr_warn("md/raid:%s: don't support reshape with journal - aborting.\n",
7131                                 mdname(mddev));
7132                         return -EINVAL;
7133                 }
7134
7135                 if (mddev->new_level != mddev->level) {
7136                         pr_warn("md/raid:%s: unsupported reshape required - aborting.\n",
7137                                 mdname(mddev));
7138                         return -EINVAL;
7139                 }
7140                 old_disks = mddev->raid_disks - mddev->delta_disks;
7141                 /* reshape_position must be on a new-stripe boundary, and one
7142                  * further up in new geometry must map after here in old
7143                  * geometry.
7144                  * If the chunk sizes are different, then as we perform reshape
7145                  * in units of the largest of the two, reshape_position needs
7146                  * be a multiple of the largest chunk size times new data disks.
7147                  */
7148                 here_new = mddev->reshape_position;
7149                 chunk_sectors = max(mddev->chunk_sectors, mddev->new_chunk_sectors);
7150                 new_data_disks = mddev->raid_disks - max_degraded;
7151                 if (sector_div(here_new, chunk_sectors * new_data_disks)) {
7152                         pr_warn("md/raid:%s: reshape_position not on a stripe boundary\n",
7153                                 mdname(mddev));
7154                         return -EINVAL;
7155                 }
7156                 reshape_offset = here_new * chunk_sectors;
7157                 /* here_new is the stripe we will write to */
7158                 here_old = mddev->reshape_position;
7159                 sector_div(here_old, chunk_sectors * (old_disks-max_degraded));
7160                 /* here_old is the first stripe that we might need to read
7161                  * from */
7162                 if (mddev->delta_disks == 0) {
7163                         /* We cannot be sure it is safe to start an in-place
7164                          * reshape.  It is only safe if user-space is monitoring
7165                          * and taking constant backups.
7166                          * mdadm always starts a situation like this in
7167                          * readonly mode so it can take control before
7168                          * allowing any writes.  So just check for that.
7169                          */
7170                         if (abs(min_offset_diff) >= mddev->chunk_sectors &&
7171                             abs(min_offset_diff) >= mddev->new_chunk_sectors)
7172                                 /* not really in-place - so OK */;
7173                         else if (mddev->ro == 0) {
7174                                 pr_warn("md/raid:%s: in-place reshape must be started in read-only mode - aborting\n",
7175                                         mdname(mddev));
7176                                 return -EINVAL;
7177                         }
7178                 } else if (mddev->reshape_backwards
7179                     ? (here_new * chunk_sectors + min_offset_diff <=
7180                        here_old * chunk_sectors)
7181                     : (here_new * chunk_sectors >=
7182                        here_old * chunk_sectors + (-min_offset_diff))) {
7183                         /* Reading from the same stripe as writing to - bad */
7184                         pr_warn("md/raid:%s: reshape_position too early for auto-recovery - aborting.\n",
7185                                 mdname(mddev));
7186                         return -EINVAL;
7187                 }
7188                 pr_debug("md/raid:%s: reshape will continue\n", mdname(mddev));
7189                 /* OK, we should be able to continue; */
7190         } else {
7191                 BUG_ON(mddev->level != mddev->new_level);
7192                 BUG_ON(mddev->layout != mddev->new_layout);
7193                 BUG_ON(mddev->chunk_sectors != mddev->new_chunk_sectors);
7194                 BUG_ON(mddev->delta_disks != 0);
7195         }
7196
7197         if (test_bit(MD_HAS_JOURNAL, &mddev->flags) &&
7198             test_bit(MD_HAS_PPL, &mddev->flags)) {
7199                 pr_warn("md/raid:%s: using journal device and PPL not allowed - disabling PPL\n",
7200                         mdname(mddev));
7201                 clear_bit(MD_HAS_PPL, &mddev->flags);
7202         }
7203
7204         if (mddev->private == NULL)
7205                 conf = setup_conf(mddev);
7206         else
7207                 conf = mddev->private;
7208
7209         if (IS_ERR(conf))
7210                 return PTR_ERR(conf);
7211
7212         if (test_bit(MD_HAS_JOURNAL, &mddev->flags)) {
7213                 if (!journal_dev) {
7214                         pr_warn("md/raid:%s: journal disk is missing, force array readonly\n",
7215                                 mdname(mddev));
7216                         mddev->ro = 1;
7217                         set_disk_ro(mddev->gendisk, 1);
7218                 } else if (mddev->recovery_cp == MaxSector)
7219                         set_bit(MD_JOURNAL_CLEAN, &mddev->flags);
7220         }
7221
7222         conf->min_offset_diff = min_offset_diff;
7223         mddev->thread = conf->thread;
7224         conf->thread = NULL;
7225         mddev->private = conf;
7226
7227         for (i = 0; i < conf->raid_disks && conf->previous_raid_disks;
7228              i++) {
7229                 rdev = conf->disks[i].rdev;
7230                 if (!rdev && conf->disks[i].replacement) {
7231                         /* The replacement is all we have yet */
7232                         rdev = conf->disks[i].replacement;
7233                         conf->disks[i].replacement = NULL;
7234                         clear_bit(Replacement, &rdev->flags);
7235                         conf->disks[i].rdev = rdev;
7236                 }
7237                 if (!rdev)
7238                         continue;
7239                 if (conf->disks[i].replacement &&
7240                     conf->reshape_progress != MaxSector) {
7241                         /* replacements and reshape simply do not mix. */
7242                         pr_warn("md: cannot handle concurrent replacement and reshape.\n");
7243                         goto abort;
7244                 }
7245                 if (test_bit(In_sync, &rdev->flags)) {
7246                         working_disks++;
7247                         continue;
7248                 }
7249                 /* This disc is not fully in-sync.  However if it
7250                  * just stored parity (beyond the recovery_offset),
7251                  * when we don't need to be concerned about the
7252                  * array being dirty.
7253                  * When reshape goes 'backwards', we never have
7254                  * partially completed devices, so we only need
7255                  * to worry about reshape going forwards.
7256                  */
7257                 /* Hack because v0.91 doesn't store recovery_offset properly. */
7258                 if (mddev->major_version == 0 &&
7259                     mddev->minor_version > 90)
7260                         rdev->recovery_offset = reshape_offset;
7261
7262                 if (rdev->recovery_offset < reshape_offset) {
7263                         /* We need to check old and new layout */
7264                         if (!only_parity(rdev->raid_disk,
7265                                          conf->algorithm,
7266                                          conf->raid_disks,
7267                                          conf->max_degraded))
7268                                 continue;
7269                 }
7270                 if (!only_parity(rdev->raid_disk,
7271                                  conf->prev_algo,
7272                                  conf->previous_raid_disks,
7273                                  conf->max_degraded))
7274                         continue;
7275                 dirty_parity_disks++;
7276         }
7277
7278         /*
7279          * 0 for a fully functional array, 1 or 2 for a degraded array.
7280          */
7281         mddev->degraded = raid5_calc_degraded(conf);
7282
7283         if (has_failed(conf)) {
7284                 pr_crit("md/raid:%s: not enough operational devices (%d/%d failed)\n",
7285                         mdname(mddev), mddev->degraded, conf->raid_disks);
7286                 goto abort;
7287         }
7288
7289         /* device size must be a multiple of chunk size */
7290         mddev->dev_sectors &= ~(mddev->chunk_sectors - 1);
7291         mddev->resync_max_sectors = mddev->dev_sectors;
7292
7293         if (mddev->degraded > dirty_parity_disks &&
7294             mddev->recovery_cp != MaxSector) {
7295                 if (test_bit(MD_HAS_PPL, &mddev->flags))
7296                         pr_crit("md/raid:%s: starting dirty degraded array with PPL.\n",
7297                                 mdname(mddev));
7298                 else if (mddev->ok_start_degraded)
7299                         pr_crit("md/raid:%s: starting dirty degraded array - data corruption possible.\n",
7300                                 mdname(mddev));
7301                 else {
7302                         pr_crit("md/raid:%s: cannot start dirty degraded array.\n",
7303                                 mdname(mddev));
7304                         goto abort;
7305                 }
7306         }
7307
7308         pr_info("md/raid:%s: raid level %d active with %d out of %d devices, algorithm %d\n",
7309                 mdname(mddev), conf->level,
7310                 mddev->raid_disks-mddev->degraded, mddev->raid_disks,
7311                 mddev->new_layout);
7312
7313         print_raid5_conf(conf);
7314
7315         if (conf->reshape_progress != MaxSector) {
7316                 conf->reshape_safe = conf->reshape_progress;
7317                 atomic_set(&conf->reshape_stripes, 0);
7318                 clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
7319                 clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
7320                 set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
7321                 set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
7322                 mddev->sync_thread = md_register_thread(md_do_sync, mddev,
7323                                                         "reshape");
7324         }
7325
7326         /* Ok, everything is just fine now */
7327         if (mddev->to_remove == &raid5_attrs_group)
7328                 mddev->to_remove = NULL;
7329         else if (mddev->kobj.sd &&
7330             sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
7331                 pr_warn("raid5: failed to create sysfs attributes for %s\n",
7332                         mdname(mddev));
7333         md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
7334
7335         if (mddev->queue) {
7336                 int chunk_size;
7337                 bool discard_supported = true;
7338                 /* read-ahead size must cover two whole stripes, which
7339                  * is 2 * (datadisks) * chunksize where 'n' is the
7340                  * number of raid devices
7341                  */
7342                 int data_disks = conf->previous_raid_disks - conf->max_degraded;
7343                 int stripe = data_disks *
7344                         ((mddev->chunk_sectors << 9) / PAGE_SIZE);
7345                 if (mddev->queue->backing_dev_info->ra_pages < 2 * stripe)
7346                         mddev->queue->backing_dev_info->ra_pages = 2 * stripe;
7347
7348                 chunk_size = mddev->chunk_sectors << 9;
7349                 blk_queue_io_min(mddev->queue, chunk_size);
7350                 blk_queue_io_opt(mddev->queue, chunk_size *
7351                                  (conf->raid_disks - conf->max_degraded));
7352                 mddev->queue->limits.raid_partial_stripes_expensive = 1;
7353                 /*
7354                  * We can only discard a whole stripe. It doesn't make sense to
7355                  * discard data disk but write parity disk
7356                  */
7357                 stripe = stripe * PAGE_SIZE;
7358                 /* Round up to power of 2, as discard handling
7359                  * currently assumes that */
7360                 while ((stripe-1) & stripe)
7361                         stripe = (stripe | (stripe-1)) + 1;
7362                 mddev->queue->limits.discard_alignment = stripe;
7363                 mddev->queue->limits.discard_granularity = stripe;
7364                 /*
7365                  * unaligned part of discard request will be ignored, so can't
7366                  * guarantee discard_zeroes_data
7367                  */
7368                 mddev->queue->limits.discard_zeroes_data = 0;
7369
7370                 blk_queue_max_write_same_sectors(mddev->queue, 0);
7371
7372                 rdev_for_each(rdev, mddev) {
7373                         disk_stack_limits(mddev->gendisk, rdev->bdev,
7374                                           rdev->data_offset << 9);
7375                         disk_stack_limits(mddev->gendisk, rdev->bdev,
7376                                           rdev->new_data_offset << 9);
7377                         /*
7378                          * discard_zeroes_data is required, otherwise data
7379                          * could be lost. Consider a scenario: discard a stripe
7380                          * (the stripe could be inconsistent if
7381                          * discard_zeroes_data is 0); write one disk of the
7382                          * stripe (the stripe could be inconsistent again
7383                          * depending on which disks are used to calculate
7384                          * parity); the disk is broken; The stripe data of this
7385                          * disk is lost.
7386                          */
7387                         if (!blk_queue_discard(bdev_get_queue(rdev->bdev)) ||
7388                             !bdev_get_queue(rdev->bdev)->
7389                                                 limits.discard_zeroes_data)
7390                                 discard_supported = false;
7391                         /* Unfortunately, discard_zeroes_data is not currently
7392                          * a guarantee - just a hint.  So we only allow DISCARD
7393                          * if the sysadmin has confirmed that only safe devices
7394                          * are in use by setting a module parameter.
7395                          */
7396                         if (!devices_handle_discard_safely) {
7397                                 if (discard_supported) {
7398                                         pr_info("md/raid456: discard support disabled due to uncertainty.\n");
7399                                         pr_info("Set raid456.devices_handle_discard_safely=Y to override.\n");
7400                                 }
7401                                 discard_supported = false;
7402                         }
7403                 }
7404
7405                 if (discard_supported &&
7406                     mddev->queue->limits.max_discard_sectors >= (stripe >> 9) &&
7407                     mddev->queue->limits.discard_granularity >= stripe)
7408                         queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
7409                                                 mddev->queue);
7410                 else
7411                         queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD,
7412                                                 mddev->queue);
7413
7414                 blk_queue_max_hw_sectors(mddev->queue, UINT_MAX);
7415         }
7416
7417         if (log_init(conf, journal_dev))
7418                 goto abort;
7419
7420         return 0;
7421 abort:
7422         md_unregister_thread(&mddev->thread);
7423         print_raid5_conf(conf);
7424         free_conf(conf);
7425         mddev->private = NULL;
7426         pr_warn("md/raid:%s: failed to run raid set.\n", mdname(mddev));
7427         return -EIO;
7428 }
7429
7430 static void raid5_free(struct mddev *mddev, void *priv)
7431 {
7432         struct r5conf *conf = priv;
7433
7434         free_conf(conf);
7435         mddev->to_remove = &raid5_attrs_group;
7436 }
7437
7438 static void raid5_status(struct seq_file *seq, struct mddev *mddev)
7439 {
7440         struct r5conf *conf = mddev->private;
7441         int i;
7442
7443         seq_printf(seq, " level %d, %dk chunk, algorithm %d", mddev->level,
7444                 conf->chunk_sectors / 2, mddev->layout);
7445         seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded);
7446         rcu_read_lock();
7447         for (i = 0; i < conf->raid_disks; i++) {
7448                 struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
7449                 seq_printf (seq, "%s", rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_");
7450         }
7451         rcu_read_unlock();
7452         seq_printf (seq, "]");
7453 }
7454
7455 static void print_raid5_conf (struct r5conf *conf)
7456 {
7457         int i;
7458         struct disk_info *tmp;
7459
7460         pr_debug("RAID conf printout:\n");
7461         if (!conf) {
7462                 pr_debug("(conf==NULL)\n");
7463                 return;
7464         }
7465         pr_debug(" --- level:%d rd:%d wd:%d\n", conf->level,
7466                conf->raid_disks,
7467                conf->raid_disks - conf->mddev->degraded);
7468
7469         for (i = 0; i < conf->raid_disks; i++) {
7470                 char b[BDEVNAME_SIZE];
7471                 tmp = conf->disks + i;
7472                 if (tmp->rdev)
7473                         pr_debug(" disk %d, o:%d, dev:%s\n",
7474                                i, !test_bit(Faulty, &tmp->rdev->flags),
7475                                bdevname(tmp->rdev->bdev, b));
7476         }
7477 }
7478
7479 static int raid5_spare_active(struct mddev *mddev)
7480 {
7481         int i;
7482         struct r5conf *conf = mddev->private;
7483         struct disk_info *tmp;
7484         int count = 0;
7485         unsigned long flags;
7486
7487         for (i = 0; i < conf->raid_disks; i++) {
7488                 tmp = conf->disks + i;
7489                 if (tmp->replacement
7490                     && tmp->replacement->recovery_offset == MaxSector
7491                     && !test_bit(Faulty, &tmp->replacement->flags)
7492                     && !test_and_set_bit(In_sync, &tmp->replacement->flags)) {
7493                         /* Replacement has just become active. */
7494                         if (!tmp->rdev
7495                             || !test_and_clear_bit(In_sync, &tmp->rdev->flags))
7496                                 count++;
7497                         if (tmp->rdev) {
7498                                 /* Replaced device not technically faulty,
7499                                  * but we need to be sure it gets removed
7500                                  * and never re-added.
7501                                  */
7502                                 set_bit(Faulty, &tmp->rdev->flags);
7503                                 sysfs_notify_dirent_safe(
7504                                         tmp->rdev->sysfs_state);
7505                         }
7506                         sysfs_notify_dirent_safe(tmp->replacement->sysfs_state);
7507                 } else if (tmp->rdev
7508                     && tmp->rdev->recovery_offset == MaxSector
7509                     && !test_bit(Faulty, &tmp->rdev->flags)
7510                     && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
7511                         count++;
7512                         sysfs_notify_dirent_safe(tmp->rdev->sysfs_state);
7513                 }
7514         }
7515         spin_lock_irqsave(&conf->device_lock, flags);
7516         mddev->degraded = raid5_calc_degraded(conf);
7517         spin_unlock_irqrestore(&conf->device_lock, flags);
7518         print_raid5_conf(conf);
7519         return count;
7520 }
7521
7522 static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
7523 {
7524         struct r5conf *conf = mddev->private;
7525         int err = 0;
7526         int number = rdev->raid_disk;
7527         struct md_rdev **rdevp;
7528         struct disk_info *p = conf->disks + number;
7529
7530         print_raid5_conf(conf);
7531         if (test_bit(Journal, &rdev->flags) && conf->log) {
7532                 /*
7533                  * we can't wait pending write here, as this is called in
7534                  * raid5d, wait will deadlock.
7535                  */
7536                 if (atomic_read(&mddev->writes_pending))
7537                         return -EBUSY;
7538                 log_exit(conf);
7539                 return 0;
7540         }
7541         if (rdev == p->rdev)
7542                 rdevp = &p->rdev;
7543         else if (rdev == p->replacement)
7544                 rdevp = &p->replacement;
7545         else
7546                 return 0;
7547
7548         if (number >= conf->raid_disks &&
7549             conf->reshape_progress == MaxSector)
7550                 clear_bit(In_sync, &rdev->flags);
7551
7552         if (test_bit(In_sync, &rdev->flags) ||
7553             atomic_read(&rdev->nr_pending)) {
7554                 err = -EBUSY;
7555                 goto abort;
7556         }
7557         /* Only remove non-faulty devices if recovery
7558          * isn't possible.
7559          */
7560         if (!test_bit(Faulty, &rdev->flags) &&
7561             mddev->recovery_disabled != conf->recovery_disabled &&
7562             !has_failed(conf) &&
7563             (!p->replacement || p->replacement == rdev) &&
7564             number < conf->raid_disks) {
7565                 err = -EBUSY;
7566                 goto abort;
7567         }
7568         *rdevp = NULL;
7569         if (!test_bit(RemoveSynchronized, &rdev->flags)) {
7570                 synchronize_rcu();
7571                 if (atomic_read(&rdev->nr_pending)) {
7572                         /* lost the race, try later */
7573                         err = -EBUSY;
7574                         *rdevp = rdev;
7575                 }
7576         }
7577         if (!err) {
7578                 err = log_modify(conf, rdev, false);
7579                 if (err)
7580                         goto abort;
7581         }
7582         if (p->replacement) {
7583                 /* We must have just cleared 'rdev' */
7584                 p->rdev = p->replacement;
7585                 clear_bit(Replacement, &p->replacement->flags);
7586                 smp_mb(); /* Make sure other CPUs may see both as identical
7587                            * but will never see neither - if they are careful
7588                            */
7589                 p->replacement = NULL;
7590                 clear_bit(WantReplacement, &rdev->flags);
7591
7592                 if (!err)
7593                         err = log_modify(conf, p->rdev, true);
7594         } else
7595                 /* We might have just removed the Replacement as faulty-
7596                  * clear the bit just in case
7597                  */
7598                 clear_bit(WantReplacement, &rdev->flags);
7599 abort:
7600
7601         print_raid5_conf(conf);
7602         return err;
7603 }
7604
7605 static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
7606 {
7607         struct r5conf *conf = mddev->private;
7608         int err = -EEXIST;
7609         int disk;
7610         struct disk_info *p;
7611         int first = 0;
7612         int last = conf->raid_disks - 1;
7613
7614         if (test_bit(Journal, &rdev->flags)) {
7615                 if (conf->log)
7616                         return -EBUSY;
7617
7618                 rdev->raid_disk = 0;
7619                 /*
7620                  * The array is in readonly mode if journal is missing, so no
7621                  * write requests running. We should be safe
7622                  */
7623                 log_init(conf, rdev);
7624                 return 0;
7625         }
7626         if (mddev->recovery_disabled == conf->recovery_disabled)
7627                 return -EBUSY;
7628
7629         if (rdev->saved_raid_disk < 0 && has_failed(conf))
7630                 /* no point adding a device */
7631                 return -EINVAL;
7632
7633         if (rdev->raid_disk >= 0)
7634                 first = last = rdev->raid_disk;
7635
7636         /*
7637          * find the disk ... but prefer rdev->saved_raid_disk
7638          * if possible.
7639          */
7640         if (rdev->saved_raid_disk >= 0 &&
7641             rdev->saved_raid_disk >= first &&
7642             conf->disks[rdev->saved_raid_disk].rdev == NULL)
7643                 first = rdev->saved_raid_disk;
7644
7645         for (disk = first; disk <= last; disk++) {
7646                 p = conf->disks + disk;
7647                 if (p->rdev == NULL) {
7648                         clear_bit(In_sync, &rdev->flags);
7649                         rdev->raid_disk = disk;
7650                         if (rdev->saved_raid_disk != disk)
7651                                 conf->fullsync = 1;
7652                         rcu_assign_pointer(p->rdev, rdev);
7653
7654                         err = log_modify(conf, rdev, true);
7655
7656                         goto out;
7657                 }
7658         }
7659         for (disk = first; disk <= last; disk++) {
7660                 p = conf->disks + disk;
7661                 if (test_bit(WantReplacement, &p->rdev->flags) &&
7662                     p->replacement == NULL) {
7663                         clear_bit(In_sync, &rdev->flags);
7664                         set_bit(Replacement, &rdev->flags);
7665                         rdev->raid_disk = disk;
7666                         err = 0;
7667                         conf->fullsync = 1;
7668                         rcu_assign_pointer(p->replacement, rdev);
7669                         break;
7670                 }
7671         }
7672 out:
7673         print_raid5_conf(conf);
7674         return err;
7675 }
7676
7677 static int raid5_resize(struct mddev *mddev, sector_t sectors)
7678 {
7679         /* no resync is happening, and there is enough space
7680          * on all devices, so we can resize.
7681          * We need to make sure resync covers any new space.
7682          * If the array is shrinking we should possibly wait until
7683          * any io in the removed space completes, but it hardly seems
7684          * worth it.
7685          */
7686         sector_t newsize;
7687         struct r5conf *conf = mddev->private;
7688
7689         if (conf->log || raid5_has_ppl(conf))
7690                 return -EINVAL;
7691         sectors &= ~((sector_t)conf->chunk_sectors - 1);
7692         newsize = raid5_size(mddev, sectors, mddev->raid_disks);
7693         if (mddev->external_size &&
7694             mddev->array_sectors > newsize)
7695                 return -EINVAL;
7696         if (mddev->bitmap) {
7697                 int ret = bitmap_resize(mddev->bitmap, sectors, 0, 0);
7698                 if (ret)
7699                         return ret;
7700         }
7701         md_set_array_sectors(mddev, newsize);
7702         if (sectors > mddev->dev_sectors &&
7703             mddev->recovery_cp > mddev->dev_sectors) {
7704                 mddev->recovery_cp = mddev->dev_sectors;
7705                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
7706         }
7707         mddev->dev_sectors = sectors;
7708         mddev->resync_max_sectors = sectors;
7709         return 0;
7710 }
7711
7712 static int check_stripe_cache(struct mddev *mddev)
7713 {
7714         /* Can only proceed if there are plenty of stripe_heads.
7715          * We need a minimum of one full stripe,, and for sensible progress
7716          * it is best to have about 4 times that.
7717          * If we require 4 times, then the default 256 4K stripe_heads will
7718          * allow for chunk sizes up to 256K, which is probably OK.
7719          * If the chunk size is greater, user-space should request more
7720          * stripe_heads first.
7721          */
7722         struct r5conf *conf = mddev->private;
7723         if (((mddev->chunk_sectors << 9) / STRIPE_SIZE) * 4
7724             > conf->min_nr_stripes ||
7725             ((mddev->new_chunk_sectors << 9) / STRIPE_SIZE) * 4
7726             > conf->min_nr_stripes) {
7727                 pr_warn("md/raid:%s: reshape: not enough stripes.  Needed %lu\n",
7728                         mdname(mddev),
7729                         ((max(mddev->chunk_sectors, mddev->new_chunk_sectors) << 9)
7730                          / STRIPE_SIZE)*4);
7731                 return 0;
7732         }
7733         return 1;
7734 }
7735
7736 static int check_reshape(struct mddev *mddev)
7737 {
7738         struct r5conf *conf = mddev->private;
7739
7740         if (conf->log || raid5_has_ppl(conf))
7741                 return -EINVAL;
7742         if (mddev->delta_disks == 0 &&
7743             mddev->new_layout == mddev->layout &&
7744             mddev->new_chunk_sectors == mddev->chunk_sectors)
7745                 return 0; /* nothing to do */
7746         if (has_failed(conf))
7747                 return -EINVAL;
7748         if (mddev->delta_disks < 0 && mddev->reshape_position == MaxSector) {
7749                 /* We might be able to shrink, but the devices must
7750                  * be made bigger first.
7751                  * For raid6, 4 is the minimum size.
7752                  * Otherwise 2 is the minimum
7753                  */
7754                 int min = 2;
7755                 if (mddev->level == 6)
7756                         min = 4;
7757                 if (mddev->raid_disks + mddev->delta_disks < min)
7758                         return -EINVAL;
7759         }
7760
7761         if (!check_stripe_cache(mddev))
7762                 return -ENOSPC;
7763
7764         if (mddev->new_chunk_sectors > mddev->chunk_sectors ||
7765             mddev->delta_disks > 0)
7766                 if (resize_chunks(conf,
7767                                   conf->previous_raid_disks
7768                                   + max(0, mddev->delta_disks),
7769                                   max(mddev->new_chunk_sectors,
7770                                       mddev->chunk_sectors)
7771                             ) < 0)
7772                         return -ENOMEM;
7773         return resize_stripes(conf, (conf->previous_raid_disks
7774                                      + mddev->delta_disks));
7775 }
7776
7777 static int raid5_start_reshape(struct mddev *mddev)
7778 {
7779         struct r5conf *conf = mddev->private;
7780         struct md_rdev *rdev;
7781         int spares = 0;
7782         unsigned long flags;
7783
7784         if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
7785                 return -EBUSY;
7786
7787         if (!check_stripe_cache(mddev))
7788                 return -ENOSPC;
7789
7790         if (has_failed(conf))
7791                 return -EINVAL;
7792
7793         rdev_for_each(rdev, mddev) {
7794                 if (!test_bit(In_sync, &rdev->flags)
7795                     && !test_bit(Faulty, &rdev->flags))
7796                         spares++;
7797         }
7798
7799         if (spares - mddev->degraded < mddev->delta_disks - conf->max_degraded)
7800                 /* Not enough devices even to make a degraded array
7801                  * of that size
7802                  */
7803                 return -EINVAL;
7804
7805         /* Refuse to reduce size of the array.  Any reductions in
7806          * array size must be through explicit setting of array_size
7807          * attribute.
7808          */
7809         if (raid5_size(mddev, 0, conf->raid_disks + mddev->delta_disks)
7810             < mddev->array_sectors) {
7811                 pr_warn("md/raid:%s: array size must be reduced before number of disks\n",
7812                         mdname(mddev));
7813                 return -EINVAL;
7814         }
7815
7816         atomic_set(&conf->reshape_stripes, 0);
7817         spin_lock_irq(&conf->device_lock);
7818         write_seqcount_begin(&conf->gen_lock);
7819         conf->previous_raid_disks = conf->raid_disks;
7820         conf->raid_disks += mddev->delta_disks;
7821         conf->prev_chunk_sectors = conf->chunk_sectors;
7822         conf->chunk_sectors = mddev->new_chunk_sectors;
7823         conf->prev_algo = conf->algorithm;
7824         conf->algorithm = mddev->new_layout;
7825         conf->generation++;
7826         /* Code that selects data_offset needs to see the generation update
7827          * if reshape_progress has been set - so a memory barrier needed.
7828          */
7829         smp_mb();
7830         if (mddev->reshape_backwards)
7831                 conf->reshape_progress = raid5_size(mddev, 0, 0);
7832         else
7833                 conf->reshape_progress = 0;
7834         conf->reshape_safe = conf->reshape_progress;
7835         write_seqcount_end(&conf->gen_lock);
7836         spin_unlock_irq(&conf->device_lock);
7837
7838         /* Now make sure any requests that proceeded on the assumption
7839          * the reshape wasn't running - like Discard or Read - have
7840          * completed.
7841          */
7842         mddev_suspend(mddev);
7843         mddev_resume(mddev);
7844
7845         /* Add some new drives, as many as will fit.
7846          * We know there are enough to make the newly sized array work.
7847          * Don't add devices if we are reducing the number of
7848          * devices in the array.  This is because it is not possible
7849          * to correctly record the "partially reconstructed" state of
7850          * such devices during the reshape and confusion could result.
7851          */
7852         if (mddev->delta_disks >= 0) {
7853                 rdev_for_each(rdev, mddev)
7854                         if (rdev->raid_disk < 0 &&
7855                             !test_bit(Faulty, &rdev->flags)) {
7856                                 if (raid5_add_disk(mddev, rdev) == 0) {
7857                                         if (rdev->raid_disk
7858                                             >= conf->previous_raid_disks)
7859                                                 set_bit(In_sync, &rdev->flags);
7860                                         else
7861                                                 rdev->recovery_offset = 0;
7862
7863                                         if (sysfs_link_rdev(mddev, rdev))
7864                                                 /* Failure here is OK */;
7865                                 }
7866                         } else if (rdev->raid_disk >= conf->previous_raid_disks
7867                                    && !test_bit(Faulty, &rdev->flags)) {
7868                                 /* This is a spare that was manually added */
7869                                 set_bit(In_sync, &rdev->flags);
7870                         }
7871
7872                 /* When a reshape changes the number of devices,
7873                  * ->degraded is measured against the larger of the
7874                  * pre and post number of devices.
7875                  */
7876                 spin_lock_irqsave(&conf->device_lock, flags);
7877                 mddev->degraded = raid5_calc_degraded(conf);
7878                 spin_unlock_irqrestore(&conf->device_lock, flags);
7879         }
7880         mddev->raid_disks = conf->raid_disks;
7881         mddev->reshape_position = conf->reshape_progress;
7882         set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
7883
7884         clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
7885         clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
7886         clear_bit(MD_RECOVERY_DONE, &mddev->recovery);
7887         set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
7888         set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
7889         mddev->sync_thread = md_register_thread(md_do_sync, mddev,
7890                                                 "reshape");
7891         if (!mddev->sync_thread) {
7892                 mddev->recovery = 0;
7893                 spin_lock_irq(&conf->device_lock);
7894                 write_seqcount_begin(&conf->gen_lock);
7895                 mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
7896                 mddev->new_chunk_sectors =
7897                         conf->chunk_sectors = conf->prev_chunk_sectors;
7898                 mddev->new_layout = conf->algorithm = conf->prev_algo;
7899                 rdev_for_each(rdev, mddev)
7900                         rdev->new_data_offset = rdev->data_offset;
7901                 smp_wmb();
7902                 conf->generation --;
7903                 conf->reshape_progress = MaxSector;
7904                 mddev->reshape_position = MaxSector;
7905                 write_seqcount_end(&conf->gen_lock);
7906                 spin_unlock_irq(&conf->device_lock);
7907                 return -EAGAIN;
7908         }
7909         conf->reshape_checkpoint = jiffies;
7910         md_wakeup_thread(mddev->sync_thread);
7911         md_new_event(mddev);
7912         return 0;
7913 }
7914
7915 /* This is called from the reshape thread and should make any
7916  * changes needed in 'conf'
7917  */
7918 static void end_reshape(struct r5conf *conf)
7919 {
7920
7921         if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
7922                 struct md_rdev *rdev;
7923
7924                 spin_lock_irq(&conf->device_lock);
7925                 conf->previous_raid_disks = conf->raid_disks;
7926                 rdev_for_each(rdev, conf->mddev)
7927                         rdev->data_offset = rdev->new_data_offset;
7928                 smp_wmb();
7929                 conf->reshape_progress = MaxSector;
7930                 conf->mddev->reshape_position = MaxSector;
7931                 spin_unlock_irq(&conf->device_lock);
7932                 wake_up(&conf->wait_for_overlap);
7933
7934                 /* read-ahead size must cover two whole stripes, which is
7935                  * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
7936                  */
7937                 if (conf->mddev->queue) {
7938                         int data_disks = conf->raid_disks - conf->max_degraded;
7939                         int stripe = data_disks * ((conf->chunk_sectors << 9)
7940                                                    / PAGE_SIZE);
7941                         if (conf->mddev->queue->backing_dev_info->ra_pages < 2 * stripe)
7942                                 conf->mddev->queue->backing_dev_info->ra_pages = 2 * stripe;
7943                 }
7944         }
7945 }
7946
7947 /* This is called from the raid5d thread with mddev_lock held.
7948  * It makes config changes to the device.
7949  */
7950 static void raid5_finish_reshape(struct mddev *mddev)
7951 {
7952         struct r5conf *conf = mddev->private;
7953
7954         if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
7955
7956                 if (mddev->delta_disks > 0) {
7957                         md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
7958                         if (mddev->queue) {
7959                                 set_capacity(mddev->gendisk, mddev->array_sectors);
7960                                 revalidate_disk(mddev->gendisk);
7961                         }
7962                 } else {
7963                         int d;
7964                         spin_lock_irq(&conf->device_lock);
7965                         mddev->degraded = raid5_calc_degraded(conf);
7966                         spin_unlock_irq(&conf->device_lock);
7967                         for (d = conf->raid_disks ;
7968                              d < conf->raid_disks - mddev->delta_disks;
7969                              d++) {
7970                                 struct md_rdev *rdev = conf->disks[d].rdev;
7971                                 if (rdev)
7972                                         clear_bit(In_sync, &rdev->flags);
7973                                 rdev = conf->disks[d].replacement;
7974                                 if (rdev)
7975                                         clear_bit(In_sync, &rdev->flags);
7976                         }
7977                 }
7978                 mddev->layout = conf->algorithm;
7979                 mddev->chunk_sectors = conf->chunk_sectors;
7980                 mddev->reshape_position = MaxSector;
7981                 mddev->delta_disks = 0;
7982                 mddev->reshape_backwards = 0;
7983         }
7984 }
7985
7986 static void raid5_quiesce(struct mddev *mddev, int state)
7987 {
7988         struct r5conf *conf = mddev->private;
7989
7990         switch(state) {
7991         case 2: /* resume for a suspend */
7992                 wake_up(&conf->wait_for_overlap);
7993                 break;
7994
7995         case 1: /* stop all writes */
7996                 lock_all_device_hash_locks_irq(conf);
7997                 /* '2' tells resync/reshape to pause so that all
7998                  * active stripes can drain
7999                  */
8000                 r5c_flush_cache(conf, INT_MAX);
8001                 conf->quiesce = 2;
8002                 wait_event_cmd(conf->wait_for_quiescent,
8003                                     atomic_read(&conf->active_stripes) == 0 &&
8004                                     atomic_read(&conf->active_aligned_reads) == 0,
8005                                     unlock_all_device_hash_locks_irq(conf),
8006                                     lock_all_device_hash_locks_irq(conf));
8007                 conf->quiesce = 1;
8008                 unlock_all_device_hash_locks_irq(conf);
8009                 /* allow reshape to continue */
8010                 wake_up(&conf->wait_for_overlap);
8011                 break;
8012
8013         case 0: /* re-enable writes */
8014                 lock_all_device_hash_locks_irq(conf);
8015                 conf->quiesce = 0;
8016                 wake_up(&conf->wait_for_quiescent);
8017                 wake_up(&conf->wait_for_overlap);
8018                 unlock_all_device_hash_locks_irq(conf);
8019                 break;
8020         }
8021         r5l_quiesce(conf->log, state);
8022 }
8023
8024 static void *raid45_takeover_raid0(struct mddev *mddev, int level)
8025 {
8026         struct r0conf *raid0_conf = mddev->private;
8027         sector_t sectors;
8028
8029         /* for raid0 takeover only one zone is supported */
8030         if (raid0_conf->nr_strip_zones > 1) {
8031                 pr_warn("md/raid:%s: cannot takeover raid0 with more than one zone.\n",
8032                         mdname(mddev));
8033                 return ERR_PTR(-EINVAL);
8034         }
8035
8036         sectors = raid0_conf->strip_zone[0].zone_end;
8037         sector_div(sectors, raid0_conf->strip_zone[0].nb_dev);
8038         mddev->dev_sectors = sectors;
8039         mddev->new_level = level;
8040         mddev->new_layout = ALGORITHM_PARITY_N;
8041         mddev->new_chunk_sectors = mddev->chunk_sectors;
8042         mddev->raid_disks += 1;
8043         mddev->delta_disks = 1;
8044         /* make sure it will be not marked as dirty */
8045         mddev->recovery_cp = MaxSector;
8046
8047         return setup_conf(mddev);
8048 }
8049
8050 static void *raid5_takeover_raid1(struct mddev *mddev)
8051 {
8052         int chunksect;
8053         void *ret;
8054
8055         if (mddev->raid_disks != 2 ||
8056             mddev->degraded > 1)
8057                 return ERR_PTR(-EINVAL);
8058
8059         /* Should check if there are write-behind devices? */
8060
8061         chunksect = 64*2; /* 64K by default */
8062
8063         /* The array must be an exact multiple of chunksize */
8064         while (chunksect && (mddev->array_sectors & (chunksect-1)))
8065                 chunksect >>= 1;
8066
8067         if ((chunksect<<9) < STRIPE_SIZE)
8068                 /* array size does not allow a suitable chunk size */
8069                 return ERR_PTR(-EINVAL);
8070
8071         mddev->new_level = 5;
8072         mddev->new_layout = ALGORITHM_LEFT_SYMMETRIC;
8073         mddev->new_chunk_sectors = chunksect;
8074
8075         ret = setup_conf(mddev);
8076         if (!IS_ERR(ret))
8077                 mddev_clear_unsupported_flags(mddev,
8078                         UNSUPPORTED_MDDEV_FLAGS);
8079         return ret;
8080 }
8081
8082 static void *raid5_takeover_raid6(struct mddev *mddev)
8083 {
8084         int new_layout;
8085
8086         switch (mddev->layout) {
8087         case ALGORITHM_LEFT_ASYMMETRIC_6:
8088                 new_layout = ALGORITHM_LEFT_ASYMMETRIC;
8089                 break;
8090         case ALGORITHM_RIGHT_ASYMMETRIC_6:
8091                 new_layout = ALGORITHM_RIGHT_ASYMMETRIC;
8092                 break;
8093         case ALGORITHM_LEFT_SYMMETRIC_6:
8094                 new_layout = ALGORITHM_LEFT_SYMMETRIC;
8095                 break;
8096         case ALGORITHM_RIGHT_SYMMETRIC_6:
8097                 new_layout = ALGORITHM_RIGHT_SYMMETRIC;
8098                 break;
8099         case ALGORITHM_PARITY_0_6:
8100                 new_layout = ALGORITHM_PARITY_0;
8101                 break;
8102         case ALGORITHM_PARITY_N:
8103                 new_layout = ALGORITHM_PARITY_N;
8104                 break;
8105         default:
8106                 return ERR_PTR(-EINVAL);
8107         }
8108         mddev->new_level = 5;
8109         mddev->new_layout = new_layout;
8110         mddev->delta_disks = -1;
8111         mddev->raid_disks -= 1;
8112         return setup_conf(mddev);
8113 }
8114
8115 static int raid5_check_reshape(struct mddev *mddev)
8116 {
8117         /* For a 2-drive array, the layout and chunk size can be changed
8118          * immediately as not restriping is needed.
8119          * For larger arrays we record the new value - after validation
8120          * to be used by a reshape pass.
8121          */
8122         struct r5conf *conf = mddev->private;
8123         int new_chunk = mddev->new_chunk_sectors;
8124
8125         if (mddev->new_layout >= 0 && !algorithm_valid_raid5(mddev->new_layout))
8126                 return -EINVAL;
8127         if (new_chunk > 0) {
8128                 if (!is_power_of_2(new_chunk))
8129                         return -EINVAL;
8130                 if (new_chunk < (PAGE_SIZE>>9))
8131                         return -EINVAL;
8132                 if (mddev->array_sectors & (new_chunk-1))
8133                         /* not factor of array size */
8134                         return -EINVAL;
8135         }
8136
8137         /* They look valid */
8138
8139         if (mddev->raid_disks == 2) {
8140                 /* can make the change immediately */
8141                 if (mddev->new_layout >= 0) {
8142                         conf->algorithm = mddev->new_layout;
8143                         mddev->layout = mddev->new_layout;
8144                 }
8145                 if (new_chunk > 0) {
8146                         conf->chunk_sectors = new_chunk ;
8147                         mddev->chunk_sectors = new_chunk;
8148                 }
8149                 set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
8150                 md_wakeup_thread(mddev->thread);
8151         }
8152         return check_reshape(mddev);
8153 }
8154
8155 static int raid6_check_reshape(struct mddev *mddev)
8156 {
8157         int new_chunk = mddev->new_chunk_sectors;
8158
8159         if (mddev->new_layout >= 0 && !algorithm_valid_raid6(mddev->new_layout))
8160                 return -EINVAL;
8161         if (new_chunk > 0) {
8162                 if (!is_power_of_2(new_chunk))
8163                         return -EINVAL;
8164                 if (new_chunk < (PAGE_SIZE >> 9))
8165                         return -EINVAL;
8166                 if (mddev->array_sectors & (new_chunk-1))
8167                         /* not factor of array size */
8168                         return -EINVAL;
8169         }
8170
8171         /* They look valid */
8172         return check_reshape(mddev);
8173 }
8174
8175 static void *raid5_takeover(struct mddev *mddev)
8176 {
8177         /* raid5 can take over:
8178          *  raid0 - if there is only one strip zone - make it a raid4 layout
8179          *  raid1 - if there are two drives.  We need to know the chunk size
8180          *  raid4 - trivial - just use a raid4 layout.
8181          *  raid6 - Providing it is a *_6 layout
8182          */
8183         if (mddev->level == 0)
8184                 return raid45_takeover_raid0(mddev, 5);
8185         if (mddev->level == 1)
8186                 return raid5_takeover_raid1(mddev);
8187         if (mddev->level == 4) {
8188                 mddev->new_layout = ALGORITHM_PARITY_N;
8189                 mddev->new_level = 5;
8190                 return setup_conf(mddev);
8191         }
8192         if (mddev->level == 6)
8193                 return raid5_takeover_raid6(mddev);
8194
8195         return ERR_PTR(-EINVAL);
8196 }
8197
8198 static void *raid4_takeover(struct mddev *mddev)
8199 {
8200         /* raid4 can take over:
8201          *  raid0 - if there is only one strip zone
8202          *  raid5 - if layout is right
8203          */
8204         if (mddev->level == 0)
8205                 return raid45_takeover_raid0(mddev, 4);
8206         if (mddev->level == 5 &&
8207             mddev->layout == ALGORITHM_PARITY_N) {
8208                 mddev->new_layout = 0;
8209                 mddev->new_level = 4;
8210                 return setup_conf(mddev);
8211         }
8212         return ERR_PTR(-EINVAL);
8213 }
8214
8215 static struct md_personality raid5_personality;
8216
8217 static void *raid6_takeover(struct mddev *mddev)
8218 {
8219         /* Currently can only take over a raid5.  We map the
8220          * personality to an equivalent raid6 personality
8221          * with the Q block at the end.
8222          */
8223         int new_layout;
8224
8225         if (mddev->pers != &raid5_personality)
8226                 return ERR_PTR(-EINVAL);
8227         if (mddev->degraded > 1)
8228                 return ERR_PTR(-EINVAL);
8229         if (mddev->raid_disks > 253)
8230                 return ERR_PTR(-EINVAL);
8231         if (mddev->raid_disks < 3)
8232                 return ERR_PTR(-EINVAL);
8233
8234         switch (mddev->layout) {
8235         case ALGORITHM_LEFT_ASYMMETRIC:
8236                 new_layout = ALGORITHM_LEFT_ASYMMETRIC_6;
8237                 break;
8238         case ALGORITHM_RIGHT_ASYMMETRIC:
8239                 new_layout = ALGORITHM_RIGHT_ASYMMETRIC_6;
8240                 break;
8241         case ALGORITHM_LEFT_SYMMETRIC:
8242                 new_layout = ALGORITHM_LEFT_SYMMETRIC_6;
8243                 break;
8244         case ALGORITHM_RIGHT_SYMMETRIC:
8245                 new_layout = ALGORITHM_RIGHT_SYMMETRIC_6;
8246                 break;
8247         case ALGORITHM_PARITY_0:
8248                 new_layout = ALGORITHM_PARITY_0_6;
8249                 break;
8250         case ALGORITHM_PARITY_N:
8251                 new_layout = ALGORITHM_PARITY_N;
8252                 break;
8253         default:
8254                 return ERR_PTR(-EINVAL);
8255         }
8256         mddev->new_level = 6;
8257         mddev->new_layout = new_layout;
8258         mddev->delta_disks = 1;
8259         mddev->raid_disks += 1;
8260         return setup_conf(mddev);
8261 }
8262
8263 static void raid5_reset_stripe_cache(struct mddev *mddev)
8264 {
8265         struct r5conf *conf = mddev->private;
8266
8267         mutex_lock(&conf->cache_size_mutex);
8268         while (conf->max_nr_stripes &&
8269                drop_one_stripe(conf))
8270                 ;
8271         while (conf->min_nr_stripes > conf->max_nr_stripes &&
8272                grow_one_stripe(conf, GFP_KERNEL))
8273                 ;
8274         mutex_unlock(&conf->cache_size_mutex);
8275 }
8276
8277 static int raid5_change_consistency_policy(struct mddev *mddev, const char *buf)
8278 {
8279         struct r5conf *conf;
8280         int err;
8281
8282         err = mddev_lock(mddev);
8283         if (err)
8284                 return err;
8285         conf = mddev->private;
8286         if (!conf) {
8287                 mddev_unlock(mddev);
8288                 return -ENODEV;
8289         }
8290
8291         if (strncmp(buf, "ppl", 3) == 0 && !raid5_has_ppl(conf)) {
8292                 mddev_suspend(mddev);
8293                 set_bit(MD_HAS_PPL, &mddev->flags);
8294                 err = log_init(conf, NULL);
8295                 if (!err)
8296                         raid5_reset_stripe_cache(mddev);
8297                 mddev_resume(mddev);
8298         } else if (strncmp(buf, "resync", 6) == 0 && raid5_has_ppl(conf)) {
8299                 mddev_suspend(mddev);
8300                 log_exit(conf);
8301                 raid5_reset_stripe_cache(mddev);
8302                 mddev_resume(mddev);
8303         } else {
8304                 err = -EINVAL;
8305         }
8306
8307         if (!err)
8308                 md_update_sb(mddev, 1);
8309
8310         mddev_unlock(mddev);
8311
8312         return err;
8313 }
8314
8315 static struct md_personality raid6_personality =
8316 {
8317         .name           = "raid6",
8318         .level          = 6,
8319         .owner          = THIS_MODULE,
8320         .make_request   = raid5_make_request,
8321         .run            = raid5_run,
8322         .free           = raid5_free,
8323         .status         = raid5_status,
8324         .error_handler  = raid5_error,
8325         .hot_add_disk   = raid5_add_disk,
8326         .hot_remove_disk= raid5_remove_disk,
8327         .spare_active   = raid5_spare_active,
8328         .sync_request   = raid5_sync_request,
8329         .resize         = raid5_resize,
8330         .size           = raid5_size,
8331         .check_reshape  = raid6_check_reshape,
8332         .start_reshape  = raid5_start_reshape,
8333         .finish_reshape = raid5_finish_reshape,
8334         .quiesce        = raid5_quiesce,
8335         .takeover       = raid6_takeover,
8336         .congested      = raid5_congested,
8337 };
8338 static struct md_personality raid5_personality =
8339 {
8340         .name           = "raid5",
8341         .level          = 5,
8342         .owner          = THIS_MODULE,
8343         .make_request   = raid5_make_request,
8344         .run            = raid5_run,
8345         .free           = raid5_free,
8346         .status         = raid5_status,
8347         .error_handler  = raid5_error,
8348         .hot_add_disk   = raid5_add_disk,
8349         .hot_remove_disk= raid5_remove_disk,
8350         .spare_active   = raid5_spare_active,
8351         .sync_request   = raid5_sync_request,
8352         .resize         = raid5_resize,
8353         .size           = raid5_size,
8354         .check_reshape  = raid5_check_reshape,
8355         .start_reshape  = raid5_start_reshape,
8356         .finish_reshape = raid5_finish_reshape,
8357         .quiesce        = raid5_quiesce,
8358         .takeover       = raid5_takeover,
8359         .congested      = raid5_congested,
8360         .change_consistency_policy = raid5_change_consistency_policy,
8361 };
8362
8363 static struct md_personality raid4_personality =
8364 {
8365         .name           = "raid4",
8366         .level          = 4,
8367         .owner          = THIS_MODULE,
8368         .make_request   = raid5_make_request,
8369         .run            = raid5_run,
8370         .free           = raid5_free,
8371         .status         = raid5_status,
8372         .error_handler  = raid5_error,
8373         .hot_add_disk   = raid5_add_disk,
8374         .hot_remove_disk= raid5_remove_disk,
8375         .spare_active   = raid5_spare_active,
8376         .sync_request   = raid5_sync_request,
8377         .resize         = raid5_resize,
8378         .size           = raid5_size,
8379         .check_reshape  = raid5_check_reshape,
8380         .start_reshape  = raid5_start_reshape,
8381         .finish_reshape = raid5_finish_reshape,
8382         .quiesce        = raid5_quiesce,
8383         .takeover       = raid4_takeover,
8384         .congested      = raid5_congested,
8385 };
8386
8387 static int __init raid5_init(void)
8388 {
8389         int ret;
8390
8391         raid5_wq = alloc_workqueue("raid5wq",
8392                 WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE|WQ_SYSFS, 0);
8393         if (!raid5_wq)
8394                 return -ENOMEM;
8395
8396         ret = cpuhp_setup_state_multi(CPUHP_MD_RAID5_PREPARE,
8397                                       "md/raid5:prepare",
8398                                       raid456_cpu_up_prepare,
8399                                       raid456_cpu_dead);
8400         if (ret) {
8401                 destroy_workqueue(raid5_wq);
8402                 return ret;
8403         }
8404         register_md_personality(&raid6_personality);
8405         register_md_personality(&raid5_personality);
8406         register_md_personality(&raid4_personality);
8407         return 0;
8408 }
8409
8410 static void raid5_exit(void)
8411 {
8412         unregister_md_personality(&raid6_personality);
8413         unregister_md_personality(&raid5_personality);
8414         unregister_md_personality(&raid4_personality);
8415         cpuhp_remove_multi_state(CPUHP_MD_RAID5_PREPARE);
8416         destroy_workqueue(raid5_wq);
8417 }
8418
8419 module_init(raid5_init);
8420 module_exit(raid5_exit);
8421 MODULE_LICENSE("GPL");
8422 MODULE_DESCRIPTION("RAID4/5/6 (striping with parity) personality for MD");
8423 MODULE_ALIAS("md-personality-4"); /* RAID5 */
8424 MODULE_ALIAS("md-raid5");
8425 MODULE_ALIAS("md-raid4");
8426 MODULE_ALIAS("md-level-5");
8427 MODULE_ALIAS("md-level-4");
8428 MODULE_ALIAS("md-personality-8"); /* RAID6 */
8429 MODULE_ALIAS("md-raid6");
8430 MODULE_ALIAS("md-level-6");
8431
8432 /* This used to be two separate modules, they were: */
8433 MODULE_ALIAS("raid5");
8434 MODULE_ALIAS("raid6");