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  *
   6  * RAID-5 management functions.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2, or (at your option)
  11  * any later version.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * (for example /usr/src/linux/COPYING); if not, write to the Free
  15  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  16  */
  17
  18
  19 #include <linux/config.h>
  20 #include <linux/module.h>
  21 #include <linux/slab.h>
  22 #include <linux/raid/raid5.h>
  23 #include <linux/highmem.h>
  24 #include <linux/bitops.h>
  25 #include <asm/atomic.h>
  26
  27 #include <linux/raid/bitmap.h>
  28
  29 /*
  30  * Stripe cache
  31  */
  32
  33 #define NR_STRIPES              256
  34 #define STRIPE_SIZE             PAGE_SIZE
  35 #define STRIPE_SHIFT            (PAGE_SHIFT - 9)
  36 #define STRIPE_SECTORS          (STRIPE_SIZE>>9)
  37 #define IO_THRESHOLD            1
  38 #define HASH_PAGES              1
  39 #define HASH_PAGES_ORDER        0
  40 #define NR_HASH                 (HASH_PAGES * PAGE_SIZE / sizeof(struct stripe_head *))
  41 #define HASH_MASK               (NR_HASH - 1)
  42
  43 #define stripe_hash(conf, sect) ((conf)->stripe_hashtbl[((sect) >> STRIPE_SHIFT) & HASH_MASK])
  44
  45 /* bio's attached to a stripe+device for I/O are linked together in bi_sector
  46  * order without overlap.  There may be several bio's per stripe+device, and
  47  * a bio could span several devices.
  48  * When walking this list for a particular stripe+device, we must never proceed
  49  * beyond a bio that extends past this device, as the next bio might no longer
  50  * be valid.
  51  * This macro is used to determine the 'next' bio in the list, given the sector
  52  * of the current stripe+device
  53  */
  54 #define r5_next_bio(bio, sect) ( ( (bio)->bi_sector + ((bio)->bi_size>>9) < sect + STRIPE_SECTORS) ? (bio)->bi_next : NULL)
  55 /*
  56  * The following can be used to debug the driver
  57  */
  58 #define RAID5_DEBUG     0
  59 #define RAID5_PARANOIA  1
  60 #if RAID5_PARANOIA && defined(CONFIG_SMP)
  61 # define CHECK_DEVLOCK() assert_spin_locked(&conf->device_lock)
  62 #else
  63 # define CHECK_DEVLOCK()
  64 #endif
  65
  66 #define PRINTK(x...) ((void)(RAID5_DEBUG && printk(x)))
  67 #if RAID5_DEBUG
  68 #define inline
  69 #define __inline__
  70 #endif
  71
  72 static void print_raid5_conf (raid5_conf_t *conf);
  73
  74 static inline void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
  75 {
  76         if (atomic_dec_and_test(&sh->count)) {
  77                 if (!list_empty(&sh->lru))
  78                         BUG();
  79                 if (atomic_read(&conf->active_stripes)==0)
  80                         BUG();
  81                 if (test_bit(STRIPE_HANDLE, &sh->state)) {
  82                         if (test_bit(STRIPE_DELAYED, &sh->state))
  83                                 list_add_tail(&sh->lru, &conf->delayed_list);
  84                         else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
  85                                  conf->seq_write == sh->bm_seq)
  86                                 list_add_tail(&sh->lru, &conf->bitmap_list);
  87                         else {
  88                                 clear_bit(STRIPE_BIT_DELAY, &sh->state);
  89                                 list_add_tail(&sh->lru, &conf->handle_list);
  90                         }
  91                         md_wakeup_thread(conf->mddev->thread);
  92                 } else {
  93                         if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
  94                                 atomic_dec(&conf->preread_active_stripes);
  95                                 if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
  96                                         md_wakeup_thread(conf->mddev->thread);
  97                         }
  98                         list_add_tail(&sh->lru, &conf->inactive_list);
  99                         atomic_dec(&conf->active_stripes);
 100                         if (!conf->inactive_blocked ||
 101                             atomic_read(&conf->active_stripes) < (NR_STRIPES*3/4))
 102                                 wake_up(&conf->wait_for_stripe);
 103                 }
 104         }
 105 }
 106 static void release_stripe(struct stripe_head *sh)
 107 {
 108         raid5_conf_t *conf = sh->raid_conf;
 109         unsigned long flags;
 110
 111         spin_lock_irqsave(&conf->device_lock, flags);
 112         __release_stripe(conf, sh);
 113         spin_unlock_irqrestore(&conf->device_lock, flags);
 114 }
 115
 116 static void remove_hash(struct stripe_head *sh)
 117 {
 118         PRINTK("remove_hash(), stripe %llu\n", (unsigned long long)sh->sector);
 119
 120         if (sh->hash_pprev) {
 121                 if (sh->hash_next)
 122                         sh->hash_next->hash_pprev = sh->hash_pprev;
 123                 *sh->hash_pprev = sh->hash_next;
 124                 sh->hash_pprev = NULL;
 125         }
 126 }
 127
 128 static __inline__ void insert_hash(raid5_conf_t *conf, struct stripe_head *sh)
 129 {
 130         struct stripe_head **shp = &stripe_hash(conf, sh->sector);
 131
 132         PRINTK("insert_hash(), stripe %llu\n", (unsigned long long)sh->sector);
 133
 134         CHECK_DEVLOCK();
 135         if ((sh->hash_next = *shp) != NULL)
 136                 (*shp)->hash_pprev = &sh->hash_next;
 137         *shp = sh;
 138         sh->hash_pprev = shp;
 139 }
 140
 141
 142 /* find an idle stripe, make sure it is unhashed, and return it. */
 143 static struct stripe_head *get_free_stripe(raid5_conf_t *conf)
 144 {
 145         struct stripe_head *sh = NULL;
 146         struct list_head *first;
 147
 148         CHECK_DEVLOCK();
 149         if (list_empty(&conf->inactive_list))
 150                 goto out;
 151         first = conf->inactive_list.next;
 152         sh = list_entry(first, struct stripe_head, lru);
 153         list_del_init(first);
 154         remove_hash(sh);
 155         atomic_inc(&conf->active_stripes);
 156 out:
 157         return sh;
 158 }
 159
 160 static void shrink_buffers(struct stripe_head *sh, int num)
 161 {
 162         struct page *p;
 163         int i;
 164
 165         for (i=0; i<num ; i++) {
 166                 p = sh->dev[i].page;
 167                 if (!p)
 168                         continue;
 169                 sh->dev[i].page = NULL;
 170                 page_cache_release(p);
 171         }
 172 }
 173
 174 static int grow_buffers(struct stripe_head *sh, int num)
 175 {
 176         int i;
 177
 178         for (i=0; i<num; i++) {
 179                 struct page *page;
 180
 181                 if (!(page = alloc_page(GFP_KERNEL))) {
 182                         return 1;
 183                 }
 184                 sh->dev[i].page = page;
 185         }
 186         return 0;
 187 }
 188
 189 static void raid5_build_block (struct stripe_head *sh, int i);
 190
 191 static inline void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx)
 192 {
 193         raid5_conf_t *conf = sh->raid_conf;
 194         int disks = conf->raid_disks, i;
 195
 196         if (atomic_read(&sh->count) != 0)
 197                 BUG();
 198         if (test_bit(STRIPE_HANDLE, &sh->state))
 199                 BUG();
 200
 201         CHECK_DEVLOCK();
 202         PRINTK("init_stripe called, stripe %llu\n",
 203                 (unsigned long long)sh->sector);
 204
 205         remove_hash(sh);
 206
 207         sh->sector = sector;
 208         sh->pd_idx = pd_idx;
 209         sh->state = 0;
 210
 211         for (i=disks; i--; ) {
 212                 struct r5dev *dev = &sh->dev[i];
 213
 214                 if (dev->toread || dev->towrite || dev->written ||
 215                     test_bit(R5_LOCKED, &dev->flags)) {
 216                         printk("sector=%llx i=%d %p %p %p %d\n",
 217                                (unsigned long long)sh->sector, i, dev->toread,
 218                                dev->towrite, dev->written,
 219                                test_bit(R5_LOCKED, &dev->flags));
 220                         BUG();
 221                 }
 222                 dev->flags = 0;
 223                 raid5_build_block(sh, i);
 224         }
 225         insert_hash(conf, sh);
 226 }
 227
 228 static struct stripe_head *__find_stripe(raid5_conf_t *conf, sector_t sector)
 229 {
 230         struct stripe_head *sh;
 231
 232         CHECK_DEVLOCK();
 233         PRINTK("__find_stripe, sector %llu\n", (unsigned long long)sector);
 234         for (sh = stripe_hash(conf, sector); sh; sh = sh->hash_next)
 235                 if (sh->sector == sector)
 236                         return sh;
 237         PRINTK("__stripe %llu not in cache\n", (unsigned long long)sector);
 238         return NULL;
 239 }
 240
 241 static void unplug_slaves(mddev_t *mddev);
 242 static void raid5_unplug_device(request_queue_t *q);
 243
 244 static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector,
 245                                              int pd_idx, int noblock)
 246 {
 247         struct stripe_head *sh;
 248
 249         PRINTK("get_stripe, sector %llu\n", (unsigned long long)sector);
 250
 251         spin_lock_irq(&conf->device_lock);
 252
 253         do {
 254                 wait_event_lock_irq(conf->wait_for_stripe,
 255                                     conf->quiesce == 0,
 256                                     conf->device_lock, /* nothing */);
 257                 sh = __find_stripe(conf, sector);
 258                 if (!sh) {
 259                         if (!conf->inactive_blocked)
 260                                 sh = get_free_stripe(conf);
 261                         if (noblock && sh == NULL)
 262                                 break;
 263                         if (!sh) {
 264                                 conf->inactive_blocked = 1;
 265                                 wait_event_lock_irq(conf->wait_for_stripe,
 266                                                     !list_empty(&conf->inactive_list) &&
 267                                                     (atomic_read(&conf->active_stripes) < (NR_STRIPES *3/4)
 268                                                      || !conf->inactive_blocked),
 269                                                     conf->device_lock,
 270                                                     unplug_slaves(conf->mddev);
 271                                         );
 272                                 conf->inactive_blocked = 0;
 273                         } else
 274                                 init_stripe(sh, sector, pd_idx);
 275                 } else {
 276                         if (atomic_read(&sh->count)) {
 277                                 if (!list_empty(&sh->lru))
 278                                         BUG();
 279                         } else {
 280                                 if (!test_bit(STRIPE_HANDLE, &sh->state))
 281                                         atomic_inc(&conf->active_stripes);
 282                                 if (list_empty(&sh->lru))
 283                                         BUG();
 284                                 list_del_init(&sh->lru);
 285                         }
 286                 }
 287         } while (sh == NULL);
 288
 289         if (sh)
 290                 atomic_inc(&sh->count);
 291
 292         spin_unlock_irq(&conf->device_lock);
 293         return sh;
 294 }
 295
 296 static int grow_stripes(raid5_conf_t *conf, int num)
 297 {
 298         struct stripe_head *sh;
 299         kmem_cache_t *sc;
 300         int devs = conf->raid_disks;
 301
 302         sprintf(conf->cache_name, "raid5/%s", mdname(conf->mddev));
 303
 304         sc = kmem_cache_create(conf->cache_name,
 305                                sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
 306                                0, 0, NULL, NULL);
 307         if (!sc)
 308                 return 1;
 309         conf->slab_cache = sc;
 310         while (num--) {
 311                 sh = kmem_cache_alloc(sc, GFP_KERNEL);
 312                 if (!sh)
 313                         return 1;
 314                 memset(sh, 0, sizeof(*sh) + (devs-1)*sizeof(struct r5dev));
 315                 sh->raid_conf = conf;
 316                 spin_lock_init(&sh->lock);
 317
 318                 if (grow_buffers(sh, conf->raid_disks)) {
 319                         shrink_buffers(sh, conf->raid_disks);
 320                         kmem_cache_free(sc, sh);
 321                         return 1;
 322                 }
 323                 /* we just created an active stripe so... */
 324                 atomic_set(&sh->count, 1);
 325                 atomic_inc(&conf->active_stripes);
 326                 INIT_LIST_HEAD(&sh->lru);
 327                 release_stripe(sh);
 328         }
 329         return 0;
 330 }
 331
 332 static void shrink_stripes(raid5_conf_t *conf)
 333 {
 334         struct stripe_head *sh;
 335
 336         while (1) {
 337                 spin_lock_irq(&conf->device_lock);
 338                 sh = get_free_stripe(conf);
 339                 spin_unlock_irq(&conf->device_lock);
 340                 if (!sh)
 341                         break;
 342                 if (atomic_read(&sh->count))
 343                         BUG();
 344                 shrink_buffers(sh, conf->raid_disks);
 345                 kmem_cache_free(conf->slab_cache, sh);
 346                 atomic_dec(&conf->active_stripes);
 347         }
 348         kmem_cache_destroy(conf->slab_cache);
 349         conf->slab_cache = NULL;
 350 }
 351
 352 static int raid5_end_read_request(struct bio * bi, unsigned int bytes_done,
 353                                    int error)
 354 {
 355         struct stripe_head *sh = bi->bi_private;
 356         raid5_conf_t *conf = sh->raid_conf;
 357         int disks = conf->raid_disks, i;
 358         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
 359
 360         if (bi->bi_size)
 361                 return 1;
 362
 363         for (i=0 ; i<disks; i++)
 364                 if (bi == &sh->dev[i].req)
 365                         break;
 366
 367         PRINTK("end_read_request %llu/%d, count: %d, uptodate %d.\n",
 368                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
 369                 uptodate);
 370         if (i == disks) {
 371                 BUG();
 372                 return 0;
 373         }
 374
 375         if (uptodate) {
 376 #if 0
 377                 struct bio *bio;
 378                 unsigned long flags;
 379                 spin_lock_irqsave(&conf->device_lock, flags);
 380                 /* we can return a buffer if we bypassed the cache or
 381                  * if the top buffer is not in highmem.  If there are
 382                  * multiple buffers, leave the extra work to
 383                  * handle_stripe
 384                  */
 385                 buffer = sh->bh_read[i];
 386                 if (buffer &&
 387                     (!PageHighMem(buffer->b_page)
 388                      || buffer->b_page == bh->b_page )
 389                         ) {
 390                         sh->bh_read[i] = buffer->b_reqnext;
 391                         buffer->b_reqnext = NULL;
 392                 } else
 393                         buffer = NULL;
 394                 spin_unlock_irqrestore(&conf->device_lock, flags);
 395                 if (sh->bh_page[i]==bh->b_page)
 396                         set_buffer_uptodate(bh);
 397                 if (buffer) {
 398                         if (buffer->b_page != bh->b_page)
 399                                 memcpy(buffer->b_data, bh->b_data, bh->b_size);
 400                         buffer->b_end_io(buffer, 1);
 401                 }
 402 #else
 403                 set_bit(R5_UPTODATE, &sh->dev[i].flags);
 404 #endif
 405                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
 406                         printk("R5: read error corrected!!\n");
 407                         clear_bit(R5_ReadError, &sh->dev[i].flags);
 408                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
 409                 }
 410         } else {
 411                 clear_bit(R5_UPTODATE, &sh->dev[i].flags);
 412                 if (conf->mddev->degraded) {
 413                         printk("R5: read error not correctable.\n");
 414                         clear_bit(R5_ReadError, &sh->dev[i].flags);
 415                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
 416                         md_error(conf->mddev, conf->disks[i].rdev);
 417                 } else if (test_bit(R5_ReWrite, &sh->dev[i].flags)) {
 418                         /* Oh, no!!! */
 419                         printk("R5: read error NOT corrected!!\n");
 420                         clear_bit(R5_ReadError, &sh->dev[i].flags);
 421                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
 422                         md_error(conf->mddev, conf->disks[i].rdev);
 423                 } else
 424                         set_bit(R5_ReadError, &sh->dev[i].flags);
 425         }
 426         rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
 427 #if 0
 428         /* must restore b_page before unlocking buffer... */
 429         if (sh->bh_page[i] != bh->b_page) {
 430                 bh->b_page = sh->bh_page[i];
 431                 bh->b_data = page_address(bh->b_page);
 432                 clear_buffer_uptodate(bh);
 433         }
 434 #endif
 435         clear_bit(R5_LOCKED, &sh->dev[i].flags);
 436         set_bit(STRIPE_HANDLE, &sh->state);
 437         release_stripe(sh);
 438         return 0;
 439 }
 440
 441 static int raid5_end_write_request (struct bio *bi, unsigned int bytes_done,
 442                                     int error)
 443 {
 444         struct stripe_head *sh = bi->bi_private;
 445         raid5_conf_t *conf = sh->raid_conf;
 446         int disks = conf->raid_disks, i;
 447         unsigned long flags;
 448         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
 449
 450         if (bi->bi_size)
 451                 return 1;
 452
 453         for (i=0 ; i<disks; i++)
 454                 if (bi == &sh->dev[i].req)
 455                         break;
 456
 457         PRINTK("end_write_request %llu/%d, count %d, uptodate: %d.\n",
 458                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
 459                 uptodate);
 460         if (i == disks) {
 461                 BUG();
 462                 return 0;
 463         }
 464
 465         spin_lock_irqsave(&conf->device_lock, flags);
 466         if (!uptodate)
 467                 md_error(conf->mddev, conf->disks[i].rdev);
 468
 469         rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
 470
 471         clear_bit(R5_LOCKED, &sh->dev[i].flags);
 472         set_bit(STRIPE_HANDLE, &sh->state);
 473         __release_stripe(conf, sh);
 474         spin_unlock_irqrestore(&conf->device_lock, flags);
 475         return 0;
 476 }
 477
 478
 479 static sector_t compute_blocknr(struct stripe_head *sh, int i);
 480
 481 static void raid5_build_block (struct stripe_head *sh, int i)
 482 {
 483         struct r5dev *dev = &sh->dev[i];
 484
 485         bio_init(&dev->req);
 486         dev->req.bi_io_vec = &dev->vec;
 487         dev->req.bi_vcnt++;
 488         dev->req.bi_max_vecs++;
 489         dev->vec.bv_page = dev->page;
 490         dev->vec.bv_len = STRIPE_SIZE;
 491         dev->vec.bv_offset = 0;
 492
 493         dev->req.bi_sector = sh->sector;
 494         dev->req.bi_private = sh;
 495
 496         dev->flags = 0;
 497         if (i != sh->pd_idx)
 498                 dev->sector = compute_blocknr(sh, i);
 499 }
 500
 501 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
 502 {
 503         char b[BDEVNAME_SIZE];
 504         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
 505         PRINTK("raid5: error called\n");
 506
 507         if (!rdev->faulty) {
 508                 mddev->sb_dirty = 1;
 509                 if (rdev->in_sync) {
 510                         conf->working_disks--;
 511                         mddev->degraded++;
 512                         conf->failed_disks++;
 513                         rdev->in_sync = 0;
 514                         /*
 515                          * if recovery was running, make sure it aborts.
 516                          */
 517                         set_bit(MD_RECOVERY_ERR, &mddev->recovery);
 518                 }
 519                 rdev->faulty = 1;
 520                 printk (KERN_ALERT
 521                         "raid5: Disk failure on %s, disabling device."
 522                         " Operation continuing on %d devices\n",
 523                         bdevname(rdev->bdev,b), conf->working_disks);
 524         }
 525 }
 526
 527 /*
 528  * Input: a 'big' sector number,
 529  * Output: index of the data and parity disk, and the sector # in them.
 530  */
 531 static sector_t raid5_compute_sector(sector_t r_sector, unsigned int raid_disks,
 532                         unsigned int data_disks, unsigned int * dd_idx,
 533                         unsigned int * pd_idx, raid5_conf_t *conf)
 534 {
 535         long stripe;
 536         unsigned long chunk_number;
 537         unsigned int chunk_offset;
 538         sector_t new_sector;
 539         int sectors_per_chunk = conf->chunk_size >> 9;
 540
 541         /* First compute the information on this sector */
 542
 543         /*
 544          * Compute the chunk number and the sector offset inside the chunk
 545          */
 546         chunk_offset = sector_div(r_sector, sectors_per_chunk);
 547         chunk_number = r_sector;
 548         BUG_ON(r_sector != chunk_number);
 549
 550         /*
 551          * Compute the stripe number
 552          */
 553         stripe = chunk_number / data_disks;
 554
 555         /*
 556          * Compute the data disk and parity disk indexes inside the stripe
 557          */
 558         *dd_idx = chunk_number % data_disks;
 559
 560         /*
 561          * Select the parity disk based on the user selected algorithm.
 562          */
 563         if (conf->level == 4)
 564                 *pd_idx = data_disks;
 565         else switch (conf->algorithm) {
 566                 case ALGORITHM_LEFT_ASYMMETRIC:
 567                         *pd_idx = data_disks - stripe % raid_disks;
 568                         if (*dd_idx >= *pd_idx)
 569                                 (*dd_idx)++;
 570                         break;
 571                 case ALGORITHM_RIGHT_ASYMMETRIC:
 572                         *pd_idx = stripe % raid_disks;
 573                         if (*dd_idx >= *pd_idx)
 574                                 (*dd_idx)++;
 575                         break;
 576                 case ALGORITHM_LEFT_SYMMETRIC:
 577                         *pd_idx = data_disks - stripe % raid_disks;
 578                         *dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks;
 579                         break;
 580                 case ALGORITHM_RIGHT_SYMMETRIC:
 581                         *pd_idx = stripe % raid_disks;
 582                         *dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks;
 583                         break;
 584                 default:
 585                         printk("raid5: unsupported algorithm %d\n",
 586                                 conf->algorithm);
 587         }
 588
 589         /*
 590          * Finally, compute the new sector number
 591          */
 592         new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
 593         return new_sector;
 594 }
 595
 596
 597 static sector_t compute_blocknr(struct stripe_head *sh, int i)
 598 {
 599         raid5_conf_t *conf = sh->raid_conf;
 600         int raid_disks = conf->raid_disks, data_disks = raid_disks - 1;
 601         sector_t new_sector = sh->sector, check;
 602         int sectors_per_chunk = conf->chunk_size >> 9;
 603         sector_t stripe;
 604         int chunk_offset;
 605         int chunk_number, dummy1, dummy2, dd_idx = i;
 606         sector_t r_sector;
 607
 608         chunk_offset = sector_div(new_sector, sectors_per_chunk);
 609         stripe = new_sector;
 610         BUG_ON(new_sector != stripe);
 611
 612
 613         switch (conf->algorithm) {
 614                 case ALGORITHM_LEFT_ASYMMETRIC:
 615                 case ALGORITHM_RIGHT_ASYMMETRIC:
 616                         if (i > sh->pd_idx)
 617                                 i--;
 618                         break;
 619                 case ALGORITHM_LEFT_SYMMETRIC:
 620                 case ALGORITHM_RIGHT_SYMMETRIC:
 621                         if (i < sh->pd_idx)
 622                                 i += raid_disks;
 623                         i -= (sh->pd_idx + 1);
 624                         break;
 625                 default:
 626                         printk("raid5: unsupported algorithm %d\n",
 627                                 conf->algorithm);
 628         }
 629
 630         chunk_number = stripe * data_disks + i;
 631         r_sector = (sector_t)chunk_number * sectors_per_chunk + chunk_offset;
 632
 633         check = raid5_compute_sector (r_sector, raid_disks, data_disks, &dummy1, &dummy2, conf);
 634         if (check != sh->sector || dummy1 != dd_idx || dummy2 != sh->pd_idx) {
 635                 printk("compute_blocknr: map not correct\n");
 636                 return 0;
 637         }
 638         return r_sector;
 639 }
 640
 641
 642
 643 /*
 644  * Copy data between a page in the stripe cache, and a bio.
 645  * There are no alignment or size guarantees between the page or the
 646  * bio except that there is some overlap.
 647  * All iovecs in the bio must be considered.
 648  */
 649 static void copy_data(int frombio, struct bio *bio,
 650                      struct page *page,
 651                      sector_t sector)
 652 {
 653         char *pa = page_address(page);
 654         struct bio_vec *bvl;
 655         int i;
 656         int page_offset;
 657
 658         if (bio->bi_sector >= sector)
 659                 page_offset = (signed)(bio->bi_sector - sector) * 512;
 660         else
 661                 page_offset = (signed)(sector - bio->bi_sector) * -512;
 662         bio_for_each_segment(bvl, bio, i) {
 663                 int len = bio_iovec_idx(bio,i)->bv_len;
 664                 int clen;
 665                 int b_offset = 0;
 666
 667                 if (page_offset < 0) {
 668                         b_offset = -page_offset;
 669                         page_offset += b_offset;
 670                         len -= b_offset;
 671                 }
 672
 673                 if (len > 0 && page_offset + len > STRIPE_SIZE)
 674                         clen = STRIPE_SIZE - page_offset;
 675                 else clen = len;
 676
 677                 if (clen > 0) {
 678                         char *ba = __bio_kmap_atomic(bio, i, KM_USER0);
 679                         if (frombio)
 680                                 memcpy(pa+page_offset, ba+b_offset, clen);
 681                         else
 682                                 memcpy(ba+b_offset, pa+page_offset, clen);
 683                         __bio_kunmap_atomic(ba, KM_USER0);
 684                 }
 685                 if (clen < len) /* hit end of page */
 686                         break;
 687                 page_offset +=  len;
 688         }
 689 }
 690
 691 #define check_xor()     do {                                            \
 692                            if (count == MAX_XOR_BLOCKS) {               \
 693                                 xor_block(count, STRIPE_SIZE, ptr);     \
 694                                 count = 1;                              \
 695                            }                                            \
 696                         } while(0)
 697
 698
 699 static void compute_block(struct stripe_head *sh, int dd_idx)
 700 {
 701         raid5_conf_t *conf = sh->raid_conf;
 702         int i, count, disks = conf->raid_disks;
 703         void *ptr[MAX_XOR_BLOCKS], *p;
 704
 705         PRINTK("compute_block, stripe %llu, idx %d\n",
 706                 (unsigned long long)sh->sector, dd_idx);
 707
 708         ptr[0] = page_address(sh->dev[dd_idx].page);
 709         memset(ptr[0], 0, STRIPE_SIZE);
 710         count = 1;
 711         for (i = disks ; i--; ) {
 712                 if (i == dd_idx)
 713                         continue;
 714                 p = page_address(sh->dev[i].page);
 715                 if (test_bit(R5_UPTODATE, &sh->dev[i].flags))
 716                         ptr[count++] = p;
 717                 else
 718                         printk("compute_block() %d, stripe %llu, %d"
 719                                 " not present\n", dd_idx,
 720                                 (unsigned long long)sh->sector, i);
 721
 722                 check_xor();
 723         }
 724         if (count != 1)
 725                 xor_block(count, STRIPE_SIZE, ptr);
 726         set_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
 727 }
 728
 729 static void compute_parity(struct stripe_head *sh, int method)
 730 {
 731         raid5_conf_t *conf = sh->raid_conf;
 732         int i, pd_idx = sh->pd_idx, disks = conf->raid_disks, count;
 733         void *ptr[MAX_XOR_BLOCKS];
 734         struct bio *chosen;
 735
 736         PRINTK("compute_parity, stripe %llu, method %d\n",
 737                 (unsigned long long)sh->sector, method);
 738
 739         count = 1;
 740         ptr[0] = page_address(sh->dev[pd_idx].page);
 741         switch(method) {
 742         case READ_MODIFY_WRITE:
 743                 if (!test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags))
 744                         BUG();
 745                 for (i=disks ; i-- ;) {
 746                         if (i==pd_idx)
 747                                 continue;
 748                         if (sh->dev[i].towrite &&
 749                             test_bit(R5_UPTODATE, &sh->dev[i].flags)) {
 750                                 ptr[count++] = page_address(sh->dev[i].page);
 751                                 chosen = sh->dev[i].towrite;
 752                                 sh->dev[i].towrite = NULL;
 753
 754                                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
 755                                         wake_up(&conf->wait_for_overlap);
 756
 757                                 if (sh->dev[i].written) BUG();
 758                                 sh->dev[i].written = chosen;
 759                                 check_xor();
 760                         }
 761                 }
 762                 break;
 763         case RECONSTRUCT_WRITE:
 764                 memset(ptr[0], 0, STRIPE_SIZE);
 765                 for (i= disks; i-- ;)
 766                         if (i!=pd_idx && sh->dev[i].towrite) {
 767                                 chosen = sh->dev[i].towrite;
 768                                 sh->dev[i].towrite = NULL;
 769
 770                                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
 771                                         wake_up(&conf->wait_for_overlap);
 772
 773                                 if (sh->dev[i].written) BUG();
 774                                 sh->dev[i].written = chosen;
 775                         }
 776                 break;
 777         case CHECK_PARITY:
 778                 break;
 779         }
 780         if (count>1) {
 781                 xor_block(count, STRIPE_SIZE, ptr);
 782                 count = 1;
 783         }
 784
 785         for (i = disks; i--;)
 786                 if (sh->dev[i].written) {
 787                         sector_t sector = sh->dev[i].sector;
 788                         struct bio *wbi = sh->dev[i].written;
 789                         while (wbi && wbi->bi_sector < sector + STRIPE_SECTORS) {
 790                                 copy_data(1, wbi, sh->dev[i].page, sector);
 791                                 wbi = r5_next_bio(wbi, sector);
 792                         }
 793
 794                         set_bit(R5_LOCKED, &sh->dev[i].flags);
 795                         set_bit(R5_UPTODATE, &sh->dev[i].flags);
 796                 }
 797
 798         switch(method) {
 799         case RECONSTRUCT_WRITE:
 800         case CHECK_PARITY:
 801                 for (i=disks; i--;)
 802                         if (i != pd_idx) {
 803                                 ptr[count++] = page_address(sh->dev[i].page);
 804                                 check_xor();
 805                         }
 806                 break;
 807         case READ_MODIFY_WRITE:
 808                 for (i = disks; i--;)
 809                         if (sh->dev[i].written) {
 810                                 ptr[count++] = page_address(sh->dev[i].page);
 811                                 check_xor();
 812                         }
 813         }
 814         if (count != 1)
 815                 xor_block(count, STRIPE_SIZE, ptr);
 816
 817         if (method != CHECK_PARITY) {
 818                 set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
 819                 set_bit(R5_LOCKED,   &sh->dev[pd_idx].flags);
 820         } else
 821                 clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
 822 }
 823
 824 /*
 825  * Each stripe/dev can have one or more bion attached.
 826  * toread/towrite point to the first in a chain.
 827  * The bi_next chain must be in order.
 828  */
 829 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
 830 {
 831         struct bio **bip;
 832         raid5_conf_t *conf = sh->raid_conf;
 833         int firstwrite=0;
 834
 835         PRINTK("adding bh b#%llu to stripe s#%llu\n",
 836                 (unsigned long long)bi->bi_sector,
 837                 (unsigned long long)sh->sector);
 838
 839
 840         spin_lock(&sh->lock);
 841         spin_lock_irq(&conf->device_lock);
 842         if (forwrite) {
 843                 bip = &sh->dev[dd_idx].towrite;
 844                 if (*bip == NULL && sh->dev[dd_idx].written == NULL)
 845                         firstwrite = 1;
 846         } else
 847                 bip = &sh->dev[dd_idx].toread;
 848         while (*bip && (*bip)->bi_sector < bi->bi_sector) {
 849                 if ((*bip)->bi_sector + ((*bip)->bi_size >> 9) > bi->bi_sector)
 850                         goto overlap;
 851                 bip = & (*bip)->bi_next;
 852         }
 853         if (*bip && (*bip)->bi_sector < bi->bi_sector + ((bi->bi_size)>>9))
 854                 goto overlap;
 855
 856         if (*bip && bi->bi_next && (*bip) != bi->bi_next)
 857                 BUG();
 858         if (*bip)
 859                 bi->bi_next = *bip;
 860         *bip = bi;
 861         bi->bi_phys_segments ++;
 862         spin_unlock_irq(&conf->device_lock);
 863         spin_unlock(&sh->lock);
 864
 865         PRINTK("added bi b#%llu to stripe s#%llu, disk %d.\n",
 866                 (unsigned long long)bi->bi_sector,
 867                 (unsigned long long)sh->sector, dd_idx);
 868
 869         if (conf->mddev->bitmap && firstwrite) {
 870                 sh->bm_seq = conf->seq_write;
 871                 bitmap_startwrite(conf->mddev->bitmap, sh->sector,
 872                                   STRIPE_SECTORS, 0);
 873                 set_bit(STRIPE_BIT_DELAY, &sh->state);
 874         }
 875
 876         if (forwrite) {
 877                 /* check if page is covered */
 878                 sector_t sector = sh->dev[dd_idx].sector;
 879                 for (bi=sh->dev[dd_idx].towrite;
 880                      sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
 881                              bi && bi->bi_sector <= sector;
 882                      bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
 883                         if (bi->bi_sector + (bi->bi_size>>9) >= sector)
 884                                 sector = bi->bi_sector + (bi->bi_size>>9);
 885                 }
 886                 if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
 887                         set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
 888         }
 889         return 1;
 890
 891  overlap:
 892         set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
 893         spin_unlock_irq(&conf->device_lock);
 894         spin_unlock(&sh->lock);
 895         return 0;
 896 }
 897
 898
 899 /*
 900  * handle_stripe - do things to a stripe.
 901  *
 902  * We lock the stripe and then examine the state of various bits
 903  * to see what needs to be done.
 904  * Possible results:
 905  *    return some read request which now have data
 906  *    return some write requests which are safely on disc
 907  *    schedule a read on some buffers
 908  *    schedule a write of some buffers
 909  *    return confirmation of parity correctness
 910  *
 911  * Parity calculations are done inside the stripe lock
 912  * buffers are taken off read_list or write_list, and bh_cache buffers
 913  * get BH_Lock set before the stripe lock is released.
 914  *
 915  */
 916
 917 static void handle_stripe(struct stripe_head *sh)
 918 {
 919         raid5_conf_t *conf = sh->raid_conf;
 920         int disks = conf->raid_disks;
 921         struct bio *return_bi= NULL;
 922         struct bio *bi;
 923         int i;
 924         int syncing;
 925         int locked=0, uptodate=0, to_read=0, to_write=0, failed=0, written=0;
 926         int non_overwrite = 0;
 927         int failed_num=0;
 928         struct r5dev *dev;
 929
 930         PRINTK("handling stripe %llu, cnt=%d, pd_idx=%d\n",
 931                 (unsigned long long)sh->sector, atomic_read(&sh->count),
 932                 sh->pd_idx);
 933
 934         spin_lock(&sh->lock);
 935         clear_bit(STRIPE_HANDLE, &sh->state);
 936         clear_bit(STRIPE_DELAYED, &sh->state);
 937
 938         syncing = test_bit(STRIPE_SYNCING, &sh->state);
 939         /* Now to look around and see what can be done */
 940
 941         for (i=disks; i--; ) {
 942                 mdk_rdev_t *rdev;
 943                 dev = &sh->dev[i];
 944                 clear_bit(R5_Insync, &dev->flags);
 945                 clear_bit(R5_Syncio, &dev->flags);
 946
 947                 PRINTK("check %d: state 0x%lx read %p write %p written %p\n",
 948                         i, dev->flags, dev->toread, dev->towrite, dev->written);
 949                 /* maybe we can reply to a read */
 950                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread) {
 951                         struct bio *rbi, *rbi2;
 952                         PRINTK("Return read for disc %d\n", i);
 953                         spin_lock_irq(&conf->device_lock);
 954                         rbi = dev->toread;
 955                         dev->toread = NULL;
 956                         if (test_and_clear_bit(R5_Overlap, &dev->flags))
 957                                 wake_up(&conf->wait_for_overlap);
 958                         spin_unlock_irq(&conf->device_lock);
 959                         while (rbi && rbi->bi_sector < dev->sector + STRIPE_SECTORS) {
 960                                 copy_data(0, rbi, dev->page, dev->sector);
 961                                 rbi2 = r5_next_bio(rbi, dev->sector);
 962                                 spin_lock_irq(&conf->device_lock);
 963                                 if (--rbi->bi_phys_segments == 0) {
 964                                         rbi->bi_next = return_bi;
 965                                         return_bi = rbi;
 966                                 }
 967                                 spin_unlock_irq(&conf->device_lock);
 968                                 rbi = rbi2;
 969                         }
 970                 }
 971
 972                 /* now count some things */
 973                 if (test_bit(R5_LOCKED, &dev->flags)) locked++;
 974                 if (test_bit(R5_UPTODATE, &dev->flags)) uptodate++;
 975
 976
 977                 if (dev->toread) to_read++;
 978                 if (dev->towrite) {
 979                         to_write++;
 980                         if (!test_bit(R5_OVERWRITE, &dev->flags))
 981                                 non_overwrite++;
 982                 }
 983                 if (dev->written) written++;
 984                 rdev = conf->disks[i].rdev; /* FIXME, should I be looking rdev */
 985                 if (!rdev || !rdev->in_sync) {
 986                         /* The ReadError flag wil just be confusing now */
 987                         clear_bit(R5_ReadError, &dev->flags);
 988                         clear_bit(R5_ReWrite, &dev->flags);
 989                 }
 990                 if (!rdev || !rdev->in_sync
 991                     || test_bit(R5_ReadError, &dev->flags)) {
 992                         failed++;
 993                         failed_num = i;
 994                 } else
 995                         set_bit(R5_Insync, &dev->flags);
 996         }
 997         PRINTK("locked=%d uptodate=%d to_read=%d"
 998                 " to_write=%d failed=%d failed_num=%d\n",
 999                 locked, uptodate, to_read, to_write, failed, failed_num);
1000         /* check if the array has lost two devices and, if so, some requests might
1001          * need to be failed
1002          */
1003         if (failed > 1 && to_read+to_write+written) {
1004                 for (i=disks; i--; ) {
1005                         int bitmap_end = 0;
1006
1007                         if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
1008                                 mdk_rdev_t *rdev = conf->disks[i].rdev;
1009                                 if (rdev && rdev->in_sync)
1010                                         /* multiple read failures in one stripe */
1011                                         md_error(conf->mddev, rdev);
1012                         }
1013
1014                         spin_lock_irq(&conf->device_lock);
1015                         /* fail all writes first */
1016                         bi = sh->dev[i].towrite;
1017                         sh->dev[i].towrite = NULL;
1018                         if (bi) { to_write--; bitmap_end = 1; }
1019
1020                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1021                                 wake_up(&conf->wait_for_overlap);
1022
1023                         while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
1024                                 struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
1025                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
1026                                 if (--bi->bi_phys_segments == 0) {
1027                                         md_write_end(conf->mddev);
1028                                         bi->bi_next = return_bi;
1029                                         return_bi = bi;
1030                                 }
1031                                 bi = nextbi;
1032                         }
1033                         /* and fail all 'written' */
1034                         bi = sh->dev[i].written;
1035                         sh->dev[i].written = NULL;
1036                         if (bi) bitmap_end = 1;
1037                         while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS) {
1038                                 struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
1039                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
1040                                 if (--bi->bi_phys_segments == 0) {
1041                                         md_write_end(conf->mddev);
1042                                         bi->bi_next = return_bi;
1043                                         return_bi = bi;
1044                                 }
1045                                 bi = bi2;
1046                         }
1047
1048                         /* fail any reads if this device is non-operational */
1049                         if (!test_bit(R5_Insync, &sh->dev[i].flags) ||
1050                             test_bit(R5_ReadError, &sh->dev[i].flags)) {
1051                                 bi = sh->dev[i].toread;
1052                                 sh->dev[i].toread = NULL;
1053                                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1054                                         wake_up(&conf->wait_for_overlap);
1055                                 if (bi) to_read--;
1056                                 while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
1057                                         struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
1058                                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
1059                                         if (--bi->bi_phys_segments == 0) {
1060                                                 bi->bi_next = return_bi;
1061                                                 return_bi = bi;
1062                                         }
1063                                         bi = nextbi;
1064                                 }
1065                         }
1066                         spin_unlock_irq(&conf->device_lock);
1067                         if (bitmap_end)
1068                                 bitmap_endwrite(conf->mddev->bitmap, sh->sector,
1069                                                 STRIPE_SECTORS, 0, 0);
1070                 }
1071         }
1072         if (failed > 1 && syncing) {
1073                 md_done_sync(conf->mddev, STRIPE_SECTORS,0);
1074                 clear_bit(STRIPE_SYNCING, &sh->state);
1075                 syncing = 0;
1076         }
1077
1078         /* might be able to return some write requests if the parity block
1079          * is safe, or on a failed drive
1080          */
1081         dev = &sh->dev[sh->pd_idx];
1082         if ( written &&
1083              ( (test_bit(R5_Insync, &dev->flags) && !test_bit(R5_LOCKED, &dev->flags) &&
1084                 test_bit(R5_UPTODATE, &dev->flags))
1085                || (failed == 1 && failed_num == sh->pd_idx))
1086             ) {
1087             /* any written block on an uptodate or failed drive can be returned.
1088              * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
1089              * never LOCKED, so we don't need to test 'failed' directly.
1090              */
1091             for (i=disks; i--; )
1092                 if (sh->dev[i].written) {
1093                     dev = &sh->dev[i];
1094                     if (!test_bit(R5_LOCKED, &dev->flags) &&
1095                          test_bit(R5_UPTODATE, &dev->flags) ) {
1096                         /* We can return any write requests */
1097                             struct bio *wbi, *wbi2;
1098                             int bitmap_end = 0;
1099                             PRINTK("Return write for disc %d\n", i);
1100                             spin_lock_irq(&conf->device_lock);
1101                             wbi = dev->written;
1102                             dev->written = NULL;
1103                             while (wbi && wbi->bi_sector < dev->sector + STRIPE_SECTORS) {
1104                                     wbi2 = r5_next_bio(wbi, dev->sector);
1105                                     if (--wbi->bi_phys_segments == 0) {
1106                                             md_write_end(conf->mddev);
1107                                             wbi->bi_next = return_bi;
1108                                             return_bi = wbi;
1109                                     }
1110                                     wbi = wbi2;
1111                             }
1112                             if (dev->towrite == NULL)
1113                                     bitmap_end = 1;
1114                             spin_unlock_irq(&conf->device_lock);
1115                             if (bitmap_end)
1116                                     bitmap_endwrite(conf->mddev->bitmap, sh->sector,
1117                                                     STRIPE_SECTORS,
1118                                                     !test_bit(STRIPE_DEGRADED, &sh->state), 0);
1119                     }
1120                 }
1121         }
1122
1123         /* Now we might consider reading some blocks, either to check/generate
1124          * parity, or to satisfy requests
1125          * or to load a block that is being partially written.
1126          */
1127         if (to_read || non_overwrite || (syncing && (uptodate < disks))) {
1128                 for (i=disks; i--;) {
1129                         dev = &sh->dev[i];
1130                         if (!test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
1131                             (dev->toread ||
1132                              (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
1133                              syncing ||
1134                              (failed && (sh->dev[failed_num].toread ||
1135                                          (sh->dev[failed_num].towrite && !test_bit(R5_OVERWRITE, &sh->dev[failed_num].flags))))
1136                                     )
1137                                 ) {
1138                                 /* we would like to get this block, possibly
1139                                  * by computing it, but we might not be able to
1140                                  */
1141                                 if (uptodate == disks-1) {
1142                                         PRINTK("Computing block %d\n", i);
1143                                         compute_block(sh, i);
1144                                         uptodate++;
1145                                 } else if (test_bit(R5_Insync, &dev->flags)) {
1146                                         set_bit(R5_LOCKED, &dev->flags);
1147                                         set_bit(R5_Wantread, &dev->flags);
1148 #if 0
1149                                         /* if I am just reading this block and we don't have
1150                                            a failed drive, or any pending writes then sidestep the cache */
1151                                         if (sh->bh_read[i] && !sh->bh_read[i]->b_reqnext &&
1152                                             ! syncing && !failed && !to_write) {
1153                                                 sh->bh_cache[i]->b_page =  sh->bh_read[i]->b_page;
1154                                                 sh->bh_cache[i]->b_data =  sh->bh_read[i]->b_data;
1155                                         }
1156 #endif
1157                                         locked++;
1158                                         PRINTK("Reading block %d (sync=%d)\n",
1159                                                 i, syncing);
1160                                         if (syncing)
1161                                                 md_sync_acct(conf->disks[i].rdev->bdev,
1162                                                              STRIPE_SECTORS);
1163                                 }
1164                         }
1165                 }
1166                 set_bit(STRIPE_HANDLE, &sh->state);
1167         }
1168
1169         /* now to consider writing and what else, if anything should be read */
1170         if (to_write) {
1171                 int rmw=0, rcw=0;
1172                 for (i=disks ; i--;) {
1173                         /* would I have to read this buffer for read_modify_write */
1174                         dev = &sh->dev[i];
1175                         if ((dev->towrite || i == sh->pd_idx) &&
1176                             (!test_bit(R5_LOCKED, &dev->flags)
1177 #if 0
1178 || sh->bh_page[i]!=bh->b_page
1179 #endif
1180                                     ) &&
1181                             !test_bit(R5_UPTODATE, &dev->flags)) {
1182                                 if (test_bit(R5_Insync, &dev->flags)
1183 /*                                  && !(!mddev->insync && i == sh->pd_idx) */
1184                                         )
1185                                         rmw++;
1186                                 else rmw += 2*disks;  /* cannot read it */
1187                         }
1188                         /* Would I have to read this buffer for reconstruct_write */
1189                         if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
1190                             (!test_bit(R5_LOCKED, &dev->flags)
1191 #if 0
1192 || sh->bh_page[i] != bh->b_page
1193 #endif
1194                                     ) &&
1195                             !test_bit(R5_UPTODATE, &dev->flags)) {
1196                                 if (test_bit(R5_Insync, &dev->flags)) rcw++;
1197                                 else rcw += 2*disks;
1198                         }
1199                 }
1200                 PRINTK("for sector %llu, rmw=%d rcw=%d\n",
1201                         (unsigned long long)sh->sector, rmw, rcw);
1202                 set_bit(STRIPE_HANDLE, &sh->state);
1203                 if (rmw < rcw && rmw > 0)
1204                         /* prefer read-modify-write, but need to get some data */
1205                         for (i=disks; i--;) {
1206                                 dev = &sh->dev[i];
1207                                 if ((dev->towrite || i == sh->pd_idx) &&
1208                                     !test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
1209                                     test_bit(R5_Insync, &dev->flags)) {
1210                                         if (test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
1211                                         {
1212                                                 PRINTK("Read_old block %d for r-m-w\n", i);
1213                                                 set_bit(R5_LOCKED, &dev->flags);
1214                                                 set_bit(R5_Wantread, &dev->flags);
1215                                                 locked++;
1216                                         } else {
1217                                                 set_bit(STRIPE_DELAYED, &sh->state);
1218                                                 set_bit(STRIPE_HANDLE, &sh->state);
1219                                         }
1220                                 }
1221                         }
1222                 if (rcw <= rmw && rcw > 0)
1223                         /* want reconstruct write, but need to get some data */
1224                         for (i=disks; i--;) {
1225                                 dev = &sh->dev[i];
1226                                 if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
1227                                     !test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
1228                                     test_bit(R5_Insync, &dev->flags)) {
1229                                         if (test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
1230                                         {
1231                                                 PRINTK("Read_old block %d for Reconstruct\n", i);
1232                                                 set_bit(R5_LOCKED, &dev->flags);
1233                                                 set_bit(R5_Wantread, &dev->flags);
1234                                                 locked++;
1235                                         } else {
1236                                                 set_bit(STRIPE_DELAYED, &sh->state);
1237                                                 set_bit(STRIPE_HANDLE, &sh->state);
1238                                         }
1239                                 }
1240                         }
1241                 /* now if nothing is locked, and if we have enough data, we can start a write request */
1242                 if (locked == 0 && (rcw == 0 ||rmw == 0) &&
1243                     !test_bit(STRIPE_BIT_DELAY, &sh->state)) {
1244                         PRINTK("Computing parity...\n");
1245                         compute_parity(sh, rcw==0 ? RECONSTRUCT_WRITE : READ_MODIFY_WRITE);
1246                         /* now every locked buffer is ready to be written */
1247                         for (i=disks; i--;)
1248                                 if (test_bit(R5_LOCKED, &sh->dev[i].flags)) {
1249                                         PRINTK("Writing block %d\n", i);
1250                                         locked++;
1251                                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
1252                                         if (!test_bit(R5_Insync, &sh->dev[i].flags)
1253                                             || (i==sh->pd_idx && failed == 0))
1254                                                 set_bit(STRIPE_INSYNC, &sh->state);
1255                                 }
1256                         if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
1257                                 atomic_dec(&conf->preread_active_stripes);
1258                                 if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
1259                                         md_wakeup_thread(conf->mddev->thread);
1260                         }
1261                 }
1262         }
1263
1264         /* maybe we need to check and possibly fix the parity for this stripe
1265          * Any reads will already have been scheduled, so we just see if enough data
1266          * is available
1267          */
1268         if (syncing && locked == 0 &&
1269             !test_bit(STRIPE_INSYNC, &sh->state) && failed <= 1) {
1270                 set_bit(STRIPE_HANDLE, &sh->state);
1271                 if (failed == 0) {
1272                         char *pagea;
1273                         if (uptodate != disks)
1274                                 BUG();
1275                         compute_parity(sh, CHECK_PARITY);
1276                         uptodate--;
1277                         pagea = page_address(sh->dev[sh->pd_idx].page);
1278                         if ((*(u32*)pagea) == 0 &&
1279                             !memcmp(pagea, pagea+4, STRIPE_SIZE-4)) {
1280                                 /* parity is correct (on disc, not in buffer any more) */
1281                                 set_bit(STRIPE_INSYNC, &sh->state);
1282                         }
1283                 }
1284                 if (!test_bit(STRIPE_INSYNC, &sh->state)) {
1285                         if (failed==0)
1286                                 failed_num = sh->pd_idx;
1287                         /* should be able to compute the missing block and write it to spare */
1288                         if (!test_bit(R5_UPTODATE, &sh->dev[failed_num].flags)) {
1289                                 if (uptodate+1 != disks)
1290                                         BUG();
1291                                 compute_block(sh, failed_num);
1292                                 uptodate++;
1293                         }
1294                         if (uptodate != disks)
1295                                 BUG();
1296                         dev = &sh->dev[failed_num];
1297                         set_bit(R5_LOCKED, &dev->flags);
1298                         set_bit(R5_Wantwrite, &dev->flags);
1299                         clear_bit(STRIPE_DEGRADED, &sh->state);
1300                         locked++;
1301                         set_bit(STRIPE_INSYNC, &sh->state);
1302                         set_bit(R5_Syncio, &dev->flags);
1303                 }
1304         }
1305         if (syncing && locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
1306                 md_done_sync(conf->mddev, STRIPE_SECTORS,1);
1307                 clear_bit(STRIPE_SYNCING, &sh->state);
1308         }
1309
1310         /* If the failed drive is just a ReadError, then we might need to progress
1311          * the repair/check process
1312          */
1313         if (failed == 1 && test_bit(R5_ReadError, &sh->dev[failed_num].flags)
1314             && !test_bit(R5_LOCKED, &sh->dev[failed_num].flags)
1315             && test_bit(R5_UPTODATE, &sh->dev[failed_num].flags)
1316                 ) {
1317                 dev = &sh->dev[failed_num];
1318                 if (!test_bit(R5_ReWrite, &dev->flags)) {
1319                         set_bit(R5_Wantwrite, &dev->flags);
1320                         set_bit(R5_ReWrite, &dev->flags);
1321                         set_bit(R5_LOCKED, &dev->flags);
1322                 } else {
1323                         /* let's read it back */
1324                         set_bit(R5_Wantread, &dev->flags);
1325                         set_bit(R5_LOCKED, &dev->flags);
1326                 }
1327         }
1328
1329         spin_unlock(&sh->lock);
1330
1331         while ((bi=return_bi)) {
1332                 int bytes = bi->bi_size;
1333
1334                 return_bi = bi->bi_next;
1335                 bi->bi_next = NULL;
1336                 bi->bi_size = 0;
1337                 bi->bi_end_io(bi, bytes, 0);
1338         }
1339         for (i=disks; i-- ;) {
1340                 int rw;
1341                 struct bio *bi;
1342                 mdk_rdev_t *rdev;
1343                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags))
1344                         rw = 1;
1345                 else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
1346                         rw = 0;
1347                 else
1348                         continue;
1349
1350                 bi = &sh->dev[i].req;
1351
1352                 bi->bi_rw = rw;
1353                 if (rw)
1354                         bi->bi_end_io = raid5_end_write_request;
1355                 else
1356                         bi->bi_end_io = raid5_end_read_request;
1357
1358                 rcu_read_lock();
1359                 rdev = conf->disks[i].rdev;
1360                 if (rdev && rdev->faulty)
1361                         rdev = NULL;
1362                 if (rdev)
1363                         atomic_inc(&rdev->nr_pending);
1364                 rcu_read_unlock();
1365
1366                 if (rdev) {
1367                         if (test_bit(R5_Syncio, &sh->dev[i].flags))
1368                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
1369
1370                         bi->bi_bdev = rdev->bdev;
1371                         PRINTK("for %llu schedule op %ld on disc %d\n",
1372                                 (unsigned long long)sh->sector, bi->bi_rw, i);
1373                         atomic_inc(&sh->count);
1374                         bi->bi_sector = sh->sector + rdev->data_offset;
1375                         bi->bi_flags = 1 << BIO_UPTODATE;
1376                         bi->bi_vcnt = 1;
1377                         bi->bi_max_vecs = 1;
1378                         bi->bi_idx = 0;
1379                         bi->bi_io_vec = &sh->dev[i].vec;
1380                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
1381                         bi->bi_io_vec[0].bv_offset = 0;
1382                         bi->bi_size = STRIPE_SIZE;
1383                         bi->bi_next = NULL;
1384                         generic_make_request(bi);
1385                 } else {
1386                         if (rw == 1)
1387                                 set_bit(STRIPE_DEGRADED, &sh->state);
1388                         PRINTK("skip op %ld on disc %d for sector %llu\n",
1389                                 bi->bi_rw, i, (unsigned long long)sh->sector);
1390                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
1391                         set_bit(STRIPE_HANDLE, &sh->state);
1392                 }
1393         }
1394 }
1395
1396 static inline void raid5_activate_delayed(raid5_conf_t *conf)
1397 {
1398         if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
1399                 while (!list_empty(&conf->delayed_list)) {
1400                         struct list_head *l = conf->delayed_list.next;
1401                         struct stripe_head *sh;
1402                         sh = list_entry(l, struct stripe_head, lru);
1403                         list_del_init(l);
1404                         clear_bit(STRIPE_DELAYED, &sh->state);
1405                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
1406                                 atomic_inc(&conf->preread_active_stripes);
1407                         list_add_tail(&sh->lru, &conf->handle_list);
1408                 }
1409         }
1410 }
1411
1412 static inline void activate_bit_delay(raid5_conf_t *conf)
1413 {
1414         /* device_lock is held */
1415         struct list_head head;
1416         list_add(&head, &conf->bitmap_list);
1417         list_del_init(&conf->bitmap_list);
1418         while (!list_empty(&head)) {
1419                 struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
1420                 list_del_init(&sh->lru);
1421                 atomic_inc(&sh->count);
1422                 __release_stripe(conf, sh);
1423         }
1424 }
1425
1426 static void unplug_slaves(mddev_t *mddev)
1427 {
1428         raid5_conf_t *conf = mddev_to_conf(mddev);
1429         int i;
1430
1431         rcu_read_lock();
1432         for (i=0; i<mddev->raid_disks; i++) {
1433                 mdk_rdev_t *rdev = conf->disks[i].rdev;
1434                 if (rdev && !rdev->faulty && atomic_read(&rdev->nr_pending)) {
1435                         request_queue_t *r_queue = bdev_get_queue(rdev->bdev);
1436
1437                         atomic_inc(&rdev->nr_pending);
1438                         rcu_read_unlock();
1439
1440                         if (r_queue->unplug_fn)
1441                                 r_queue->unplug_fn(r_queue);
1442
1443                         rdev_dec_pending(rdev, mddev);
1444                         rcu_read_lock();
1445                 }
1446         }
1447         rcu_read_unlock();
1448 }
1449
1450 static void raid5_unplug_device(request_queue_t *q)
1451 {
1452         mddev_t *mddev = q->queuedata;
1453         raid5_conf_t *conf = mddev_to_conf(mddev);
1454         unsigned long flags;
1455
1456         spin_lock_irqsave(&conf->device_lock, flags);
1457
1458         if (blk_remove_plug(q)) {
1459                 conf->seq_flush++;
1460                 raid5_activate_delayed(conf);
1461         }
1462         md_wakeup_thread(mddev->thread);
1463
1464         spin_unlock_irqrestore(&conf->device_lock, flags);
1465
1466         unplug_slaves(mddev);
1467 }
1468
1469 static int raid5_issue_flush(request_queue_t *q, struct gendisk *disk,
1470                              sector_t *error_sector)
1471 {
1472         mddev_t *mddev = q->queuedata;
1473         raid5_conf_t *conf = mddev_to_conf(mddev);
1474         int i, ret = 0;
1475
1476         rcu_read_lock();
1477         for (i=0; i<mddev->raid_disks && ret == 0; i++) {
1478                 mdk_rdev_t *rdev = conf->disks[i].rdev;
1479                 if (rdev && !rdev->faulty) {
1480                         struct block_device *bdev = rdev->bdev;
1481                         request_queue_t *r_queue = bdev_get_queue(bdev);
1482
1483                         if (!r_queue->issue_flush_fn)
1484                                 ret = -EOPNOTSUPP;
1485                         else {
1486                                 atomic_inc(&rdev->nr_pending);
1487                                 rcu_read_unlock();
1488                                 ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk,
1489                                                               error_sector);
1490                                 rdev_dec_pending(rdev, mddev);
1491                                 rcu_read_lock();
1492                         }
1493                 }
1494         }
1495         rcu_read_unlock();
1496         return ret;
1497 }
1498
1499 static inline void raid5_plug_device(raid5_conf_t *conf)
1500 {
1501         spin_lock_irq(&conf->device_lock);
1502         blk_plug_device(conf->mddev->queue);
1503         spin_unlock_irq(&conf->device_lock);
1504 }
1505
1506 static int make_request (request_queue_t *q, struct bio * bi)
1507 {
1508         mddev_t *mddev = q->queuedata;
1509         raid5_conf_t *conf = mddev_to_conf(mddev);
1510         const unsigned int raid_disks = conf->raid_disks;
1511         const unsigned int data_disks = raid_disks - 1;
1512         unsigned int dd_idx, pd_idx;
1513         sector_t new_sector;
1514         sector_t logical_sector, last_sector;
1515         struct stripe_head *sh;
1516         const int rw = bio_data_dir(bi);
1517
1518         if (unlikely(bio_barrier(bi))) {
1519                 bio_endio(bi, bi->bi_size, -EOPNOTSUPP);
1520                 return 0;
1521         }
1522
1523         md_write_start(mddev, bi);
1524
1525         disk_stat_inc(mddev->gendisk, ios[rw]);
1526         disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bi));
1527
1528         logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
1529         last_sector = bi->bi_sector + (bi->bi_size>>9);
1530         bi->bi_next = NULL;
1531         bi->bi_phys_segments = 1;       /* over-loaded to count active stripes */
1532
1533         for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
1534                 DEFINE_WAIT(w);
1535
1536                 new_sector = raid5_compute_sector(logical_sector,
1537                                                   raid_disks, data_disks, &dd_idx, &pd_idx, conf);
1538
1539                 PRINTK("raid5: make_request, sector %llu logical %llu\n",
1540                         (unsigned long long)new_sector,
1541                         (unsigned long long)logical_sector);
1542
1543         retry:
1544                 prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
1545                 sh = get_active_stripe(conf, new_sector, pd_idx, (bi->bi_rw&RWA_MASK));
1546                 if (sh) {
1547                         if (!add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK))) {
1548                                 /* Add failed due to overlap.  Flush everything
1549                                  * and wait a while
1550                                  */
1551                                 raid5_unplug_device(mddev->queue);
1552                                 release_stripe(sh);
1553                                 schedule();
1554                                 goto retry;
1555                         }
1556                         finish_wait(&conf->wait_for_overlap, &w);
1557                         raid5_plug_device(conf);
1558                         handle_stripe(sh);
1559                         release_stripe(sh);
1560
1561                 } else {
1562                         /* cannot get stripe for read-ahead, just give-up */
1563                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
1564                         finish_wait(&conf->wait_for_overlap, &w);
1565                         break;
1566                 }
1567
1568         }
1569         spin_lock_irq(&conf->device_lock);
1570         if (--bi->bi_phys_segments == 0) {
1571                 int bytes = bi->bi_size;
1572
1573                 if ( bio_data_dir(bi) == WRITE )
1574                         md_write_end(mddev);
1575                 bi->bi_size = 0;
1576                 bi->bi_end_io(bi, bytes, 0);
1577         }
1578         spin_unlock_irq(&conf->device_lock);
1579         return 0;
1580 }
1581
1582 /* FIXME go_faster isn't used */
1583 static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
1584 {
1585         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
1586         struct stripe_head *sh;
1587         int sectors_per_chunk = conf->chunk_size >> 9;
1588         sector_t x;
1589         unsigned long stripe;
1590         int chunk_offset;
1591         int dd_idx, pd_idx;
1592         sector_t first_sector;
1593         int raid_disks = conf->raid_disks;
1594         int data_disks = raid_disks-1;
1595         sector_t max_sector = mddev->size << 1;
1596         int sync_blocks;
1597
1598         if (sector_nr >= max_sector) {
1599                 /* just being told to finish up .. nothing much to do */
1600                 unplug_slaves(mddev);
1601
1602                 if (mddev->curr_resync < max_sector) /* aborted */
1603                         bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
1604                                         &sync_blocks, 1);
1605                 else /* compelted sync */
1606                         conf->fullsync = 0;
1607                 bitmap_close_sync(mddev->bitmap);
1608
1609                 return 0;
1610         }
1611         /* if there is 1 or more failed drives and we are trying
1612          * to resync, then assert that we are finished, because there is
1613          * nothing we can do.
1614          */
1615         if (mddev->degraded >= 1 && test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
1616                 sector_t rv = (mddev->size << 1) - sector_nr;
1617                 *skipped = 1;
1618                 return rv;
1619         }
1620         if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
1621             !conf->fullsync && sync_blocks >= STRIPE_SECTORS) {
1622                 /* we can skip this block, and probably more */
1623                 sync_blocks /= STRIPE_SECTORS;
1624                 *skipped = 1;
1625                 return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
1626         }
1627
1628         x = sector_nr;
1629         chunk_offset = sector_div(x, sectors_per_chunk);
1630         stripe = x;
1631         BUG_ON(x != stripe);
1632
1633         first_sector = raid5_compute_sector((sector_t)stripe*data_disks*sectors_per_chunk
1634                 + chunk_offset, raid_disks, data_disks, &dd_idx, &pd_idx, conf);
1635         sh = get_active_stripe(conf, sector_nr, pd_idx, 1);
1636         if (sh == NULL) {
1637                 sh = get_active_stripe(conf, sector_nr, pd_idx, 0);
1638                 /* make sure we don't swamp the stripe cache if someone else
1639                  * is trying to get access
1640                  */
1641                 schedule_timeout_uninterruptible(1);
1642         }
1643         bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 0);
1644         spin_lock(&sh->lock);
1645         set_bit(STRIPE_SYNCING, &sh->state);
1646         clear_bit(STRIPE_INSYNC, &sh->state);
1647         spin_unlock(&sh->lock);
1648
1649         handle_stripe(sh);
1650         release_stripe(sh);
1651
1652         return STRIPE_SECTORS;
1653 }
1654
1655 /*
1656  * This is our raid5 kernel thread.
1657  *
1658  * We scan the hash table for stripes which can be handled now.
1659  * During the scan, completed stripes are saved for us by the interrupt
1660  * handler, so that they will not have to wait for our next wakeup.
1661  */
1662 static void raid5d (mddev_t *mddev)
1663 {
1664         struct stripe_head *sh;
1665         raid5_conf_t *conf = mddev_to_conf(mddev);
1666         int handled;
1667
1668         PRINTK("+++ raid5d active\n");
1669
1670         md_check_recovery(mddev);
1671
1672         handled = 0;
1673         spin_lock_irq(&conf->device_lock);
1674         while (1) {
1675                 struct list_head *first;
1676
1677                 if (conf->seq_flush - conf->seq_write > 0) {
1678                         int seq = conf->seq_flush;
1679                         bitmap_unplug(mddev->bitmap);
1680                         conf->seq_write = seq;
1681                         activate_bit_delay(conf);
1682                 }
1683
1684                 if (list_empty(&conf->handle_list) &&
1685                     atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD &&
1686                     !blk_queue_plugged(mddev->queue) &&
1687                     !list_empty(&conf->delayed_list))
1688                         raid5_activate_delayed(conf);
1689
1690                 if (list_empty(&conf->handle_list))
1691                         break;
1692
1693                 first = conf->handle_list.next;
1694                 sh = list_entry(first, struct stripe_head, lru);
1695
1696                 list_del_init(first);
1697                 atomic_inc(&sh->count);
1698                 if (atomic_read(&sh->count)!= 1)
1699                         BUG();
1700                 spin_unlock_irq(&conf->device_lock);
1701
1702                 handled++;
1703                 handle_stripe(sh);
1704                 release_stripe(sh);
1705
1706                 spin_lock_irq(&conf->device_lock);
1707         }
1708         PRINTK("%d stripes handled\n", handled);
1709
1710         spin_unlock_irq(&conf->device_lock);
1711
1712         unplug_slaves(mddev);
1713
1714         PRINTK("--- raid5d inactive\n");
1715 }
1716
1717 static int run(mddev_t *mddev)
1718 {
1719         raid5_conf_t *conf;
1720         int raid_disk, memory;
1721         mdk_rdev_t *rdev;
1722         struct disk_info *disk;
1723         struct list_head *tmp;
1724
1725         if (mddev->level != 5 && mddev->level != 4) {
1726                 printk("raid5: %s: raid level not set to 4/5 (%d)\n", mdname(mddev), mddev->level);
1727                 return -EIO;
1728         }
1729
1730         mddev->private = kmalloc (sizeof (raid5_conf_t)
1731                                   + mddev->raid_disks * sizeof(struct disk_info),
1732                                   GFP_KERNEL);
1733         if ((conf = mddev->private) == NULL)
1734                 goto abort;
1735         memset (conf, 0, sizeof (*conf) + mddev->raid_disks * sizeof(struct disk_info) );
1736         conf->mddev = mddev;
1737
1738         if ((conf->stripe_hashtbl = (struct stripe_head **) __get_free_pages(GFP_ATOMIC, HASH_PAGES_ORDER)) == NULL)
1739                 goto abort;
1740         memset(conf->stripe_hashtbl, 0, HASH_PAGES * PAGE_SIZE);
1741
1742         spin_lock_init(&conf->device_lock);
1743         init_waitqueue_head(&conf->wait_for_stripe);
1744         init_waitqueue_head(&conf->wait_for_overlap);
1745         INIT_LIST_HEAD(&conf->handle_list);
1746         INIT_LIST_HEAD(&conf->delayed_list);
1747         INIT_LIST_HEAD(&conf->bitmap_list);
1748         INIT_LIST_HEAD(&conf->inactive_list);
1749         atomic_set(&conf->active_stripes, 0);
1750         atomic_set(&conf->preread_active_stripes, 0);
1751
1752         PRINTK("raid5: run(%s) called.\n", mdname(mddev));
1753
1754         ITERATE_RDEV(mddev,rdev,tmp) {
1755                 raid_disk = rdev->raid_disk;
1756                 if (raid_disk >= mddev->raid_disks
1757                     || raid_disk < 0)
1758                         continue;
1759                 disk = conf->disks + raid_disk;
1760
1761                 disk->rdev = rdev;
1762
1763                 if (rdev->in_sync) {
1764                         char b[BDEVNAME_SIZE];
1765                         printk(KERN_INFO "raid5: device %s operational as raid"
1766                                 " disk %d\n", bdevname(rdev->bdev,b),
1767                                 raid_disk);
1768                         conf->working_disks++;
1769                 }
1770         }
1771
1772         conf->raid_disks = mddev->raid_disks;
1773         /*
1774          * 0 for a fully functional array, 1 for a degraded array.
1775          */
1776         mddev->degraded = conf->failed_disks = conf->raid_disks - conf->working_disks;
1777         conf->mddev = mddev;
1778         conf->chunk_size = mddev->chunk_size;
1779         conf->level = mddev->level;
1780         conf->algorithm = mddev->layout;
1781         conf->max_nr_stripes = NR_STRIPES;
1782
1783         /* device size must be a multiple of chunk size */
1784         mddev->size &= ~(mddev->chunk_size/1024 -1);
1785         mddev->resync_max_sectors = mddev->size << 1;
1786
1787         if (!conf->chunk_size || conf->chunk_size % 4) {
1788                 printk(KERN_ERR "raid5: invalid chunk size %d for %s\n",
1789                         conf->chunk_size, mdname(mddev));
1790                 goto abort;
1791         }
1792         if (conf->algorithm > ALGORITHM_RIGHT_SYMMETRIC) {
1793                 printk(KERN_ERR
1794                         "raid5: unsupported parity algorithm %d for %s\n",
1795                         conf->algorithm, mdname(mddev));
1796                 goto abort;
1797         }
1798         if (mddev->degraded > 1) {
1799                 printk(KERN_ERR "raid5: not enough operational devices for %s"
1800                         " (%d/%d failed)\n",
1801                         mdname(mddev), conf->failed_disks, conf->raid_disks);
1802                 goto abort;
1803         }
1804
1805         if (mddev->degraded == 1 &&
1806             mddev->recovery_cp != MaxSector) {
1807                 printk(KERN_ERR
1808                         "raid5: cannot start dirty degraded array for %s\n",
1809                         mdname(mddev));
1810                 goto abort;
1811         }
1812
1813         {
1814                 mddev->thread = md_register_thread(raid5d, mddev, "%s_raid5");
1815                 if (!mddev->thread) {
1816                         printk(KERN_ERR
1817                                 "raid5: couldn't allocate thread for %s\n",
1818                                 mdname(mddev));
1819                         goto abort;
1820                 }
1821         }
1822 memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
1823                  conf->raid_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
1824         if (grow_stripes(conf, conf->max_nr_stripes)) {
1825                 printk(KERN_ERR
1826                         "raid5: couldn't allocate %dkB for buffers\n", memory);
1827                 shrink_stripes(conf);
1828                 md_unregister_thread(mddev->thread);
1829                 goto abort;
1830         } else
1831                 printk(KERN_INFO "raid5: allocated %dkB for %s\n",
1832                         memory, mdname(mddev));
1833
1834         if (mddev->degraded == 0)
1835                 printk("raid5: raid level %d set %s active with %d out of %d"
1836                         " devices, algorithm %d\n", conf->level, mdname(mddev),
1837                         mddev->raid_disks-mddev->degraded, mddev->raid_disks,
1838                         conf->algorithm);
1839         else
1840                 printk(KERN_ALERT "raid5: raid level %d set %s active with %d"
1841                         " out of %d devices, algorithm %d\n", conf->level,
1842                         mdname(mddev), mddev->raid_disks - mddev->degraded,
1843                         mddev->raid_disks, conf->algorithm);
1844
1845         print_raid5_conf(conf);
1846
1847         /* read-ahead size must cover two whole stripes, which is
1848          * 2 * (n-1) * chunksize where 'n' is the number of raid devices
1849          */
1850         {
1851                 int stripe = (mddev->raid_disks-1) * mddev->chunk_size
1852                         / PAGE_CACHE_SIZE;
1853                 if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
1854                         mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
1855         }
1856
1857         /* Ok, everything is just fine now */
1858
1859         if (mddev->bitmap)
1860                 mddev->thread->timeout = mddev->bitmap->daemon_sleep * HZ;
1861
1862         mddev->queue->unplug_fn = raid5_unplug_device;
1863         mddev->queue->issue_flush_fn = raid5_issue_flush;
1864
1865         mddev->array_size =  mddev->size * (mddev->raid_disks - 1);
1866         return 0;
1867 abort:
1868         if (conf) {
1869                 print_raid5_conf(conf);
1870                 if (conf->stripe_hashtbl)
1871                         free_pages((unsigned long) conf->stripe_hashtbl,
1872                                                         HASH_PAGES_ORDER);
1873                 kfree(conf);
1874         }
1875         mddev->private = NULL;
1876         printk(KERN_ALERT "raid5: failed to run raid set %s\n", mdname(mddev));
1877         return -EIO;
1878 }
1879
1880
1881
1882 static int stop (mddev_t *mddev)
1883 {
1884         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
1885
1886         md_unregister_thread(mddev->thread);
1887         mddev->thread = NULL;
1888         shrink_stripes(conf);
1889         free_pages((unsigned long) conf->stripe_hashtbl, HASH_PAGES_ORDER);
1890         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
1891         kfree(conf);
1892         mddev->private = NULL;
1893         return 0;
1894 }
1895
1896 #if RAID5_DEBUG
1897 static void print_sh (struct stripe_head *sh)
1898 {
1899         int i;
1900
1901         printk("sh %llu, pd_idx %d, state %ld.\n",
1902                 (unsigned long long)sh->sector, sh->pd_idx, sh->state);
1903         printk("sh %llu,  count %d.\n",
1904                 (unsigned long long)sh->sector, atomic_read(&sh->count));
1905         printk("sh %llu, ", (unsigned long long)sh->sector);
1906         for (i = 0; i < sh->raid_conf->raid_disks; i++) {
1907                 printk("(cache%d: %p %ld) ",
1908                         i, sh->dev[i].page, sh->dev[i].flags);
1909         }
1910         printk("\n");
1911 }
1912
1913 static void printall (raid5_conf_t *conf)
1914 {
1915         struct stripe_head *sh;
1916         int i;
1917
1918         spin_lock_irq(&conf->device_lock);
1919         for (i = 0; i < NR_HASH; i++) {
1920                 sh = conf->stripe_hashtbl[i];
1921                 for (; sh; sh = sh->hash_next) {
1922                         if (sh->raid_conf != conf)
1923                                 continue;
1924                         print_sh(sh);
1925                 }
1926         }
1927         spin_unlock_irq(&conf->device_lock);
1928 }
1929 #endif
1930
1931 static void status (struct seq_file *seq, mddev_t *mddev)
1932 {
1933         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
1934         int i;
1935
1936         seq_printf (seq, " level %d, %dk chunk, algorithm %d", mddev->level, mddev->chunk_size >> 10, mddev->layout);
1937         seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->working_disks);
1938         for (i = 0; i < conf->raid_disks; i++)
1939                 seq_printf (seq, "%s",
1940                                conf->disks[i].rdev &&
1941                                conf->disks[i].rdev->in_sync ? "U" : "_");
1942         seq_printf (seq, "]");
1943 #if RAID5_DEBUG
1944 #define D(x) \
1945         seq_printf (seq, "<"#x":%d>", atomic_read(&conf->x))
1946         printall(conf);
1947 #endif
1948 }
1949
1950 static void print_raid5_conf (raid5_conf_t *conf)
1951 {
1952         int i;
1953         struct disk_info *tmp;
1954
1955         printk("RAID5 conf printout:\n");
1956         if (!conf) {
1957                 printk("(conf==NULL)\n");
1958                 return;
1959         }
1960         printk(" --- rd:%d wd:%d fd:%d\n", conf->raid_disks,
1961                  conf->working_disks, conf->failed_disks);
1962
1963         for (i = 0; i < conf->raid_disks; i++) {
1964                 char b[BDEVNAME_SIZE];
1965                 tmp = conf->disks + i;
1966                 if (tmp->rdev)
1967                 printk(" disk %d, o:%d, dev:%s\n",
1968                         i, !tmp->rdev->faulty,
1969                         bdevname(tmp->rdev->bdev,b));
1970         }
1971 }
1972
1973 static int raid5_spare_active(mddev_t *mddev)
1974 {
1975         int i;
1976         raid5_conf_t *conf = mddev->private;
1977         struct disk_info *tmp;
1978
1979         for (i = 0; i < conf->raid_disks; i++) {
1980                 tmp = conf->disks + i;
1981                 if (tmp->rdev
1982                     && !tmp->rdev->faulty
1983                     && !tmp->rdev->in_sync) {
1984                         mddev->degraded--;
1985                         conf->failed_disks--;
1986                         conf->working_disks++;
1987                         tmp->rdev->in_sync = 1;
1988                 }
1989         }
1990         print_raid5_conf(conf);
1991         return 0;
1992 }
1993
1994 static int raid5_remove_disk(mddev_t *mddev, int number)
1995 {
1996         raid5_conf_t *conf = mddev->private;
1997         int err = 0;
1998         mdk_rdev_t *rdev;
1999         struct disk_info *p = conf->disks + number;
2000
2001         print_raid5_conf(conf);
2002         rdev = p->rdev;
2003         if (rdev) {
2004                 if (rdev->in_sync ||
2005                     atomic_read(&rdev->nr_pending)) {
2006                         err = -EBUSY;
2007                         goto abort;
2008                 }
2009                 p->rdev = NULL;
2010                 synchronize_rcu();
2011                 if (atomic_read(&rdev->nr_pending)) {
2012                         /* lost the race, try later */
2013                         err = -EBUSY;
2014                         p->rdev = rdev;
2015                 }
2016         }
2017 abort:
2018
2019         print_raid5_conf(conf);
2020         return err;
2021 }
2022
2023 static int raid5_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
2024 {
2025         raid5_conf_t *conf = mddev->private;
2026         int found = 0;
2027         int disk;
2028         struct disk_info *p;
2029
2030         if (mddev->degraded > 1)
2031                 /* no point adding a device */
2032                 return 0;
2033
2034         /*
2035          * find the disk ...
2036          */
2037         for (disk=0; disk < mddev->raid_disks; disk++)
2038                 if ((p=conf->disks + disk)->rdev == NULL) {
2039                         rdev->in_sync = 0;
2040                         rdev->raid_disk = disk;
2041                         found = 1;
2042                         if (rdev->saved_raid_disk != disk)
2043                                 conf->fullsync = 1;
2044                         p->rdev = rdev;
2045                         break;
2046                 }
2047         print_raid5_conf(conf);
2048         return found;
2049 }
2050
2051 static int raid5_resize(mddev_t *mddev, sector_t sectors)
2052 {
2053         /* no resync is happening, and there is enough space
2054          * on all devices, so we can resize.
2055          * We need to make sure resync covers any new space.
2056          * If the array is shrinking we should possibly wait until
2057          * any io in the removed space completes, but it hardly seems
2058          * worth it.
2059          */
2060         sectors &= ~((sector_t)mddev->chunk_size/512 - 1);
2061         mddev->array_size = (sectors * (mddev->raid_disks-1))>>1;
2062         set_capacity(mddev->gendisk, mddev->array_size << 1);
2063         mddev->changed = 1;
2064         if (sectors/2  > mddev->size && mddev->recovery_cp == MaxSector) {
2065                 mddev->recovery_cp = mddev->size << 1;
2066                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
2067         }
2068         mddev->size = sectors /2;
2069         mddev->resync_max_sectors = sectors;
2070         return 0;
2071 }
2072
2073 static void raid5_quiesce(mddev_t *mddev, int state)
2074 {
2075         raid5_conf_t *conf = mddev_to_conf(mddev);
2076
2077         switch(state) {
2078         case 1: /* stop all writes */
2079                 spin_lock_irq(&conf->device_lock);
2080                 conf->quiesce = 1;
2081                 wait_event_lock_irq(conf->wait_for_stripe,
2082                                     atomic_read(&conf->active_stripes) == 0,
2083                                     conf->device_lock, /* nothing */);
2084                 spin_unlock_irq(&conf->device_lock);
2085                 break;
2086
2087         case 0: /* re-enable writes */
2088                 spin_lock_irq(&conf->device_lock);
2089                 conf->quiesce = 0;
2090                 wake_up(&conf->wait_for_stripe);
2091                 spin_unlock_irq(&conf->device_lock);
2092                 break;
2093         }
2094         if (mddev->thread) {
2095                 if (mddev->bitmap)
2096                         mddev->thread->timeout = mddev->bitmap->daemon_sleep * HZ;
2097                 else
2098                         mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;
2099                 md_wakeup_thread(mddev->thread);
2100         }
2101 }
2102 static mdk_personality_t raid5_personality=
2103 {
2104         .name           = "raid5",
2105         .owner          = THIS_MODULE,
2106         .make_request   = make_request,
2107         .run            = run,
2108         .stop           = stop,
2109         .status         = status,
2110         .error_handler  = error,
2111         .hot_add_disk   = raid5_add_disk,
2112         .hot_remove_disk= raid5_remove_disk,
2113         .spare_active   = raid5_spare_active,
2114         .sync_request   = sync_request,
2115         .resize         = raid5_resize,
2116         .quiesce        = raid5_quiesce,
2117 };
2118
2119 static int __init raid5_init (void)
2120 {
2121         return register_md_personality (RAID5, &raid5_personality);
2122 }
2123
2124 static void raid5_exit (void)
2125 {
2126         unregister_md_personality (RAID5);
2127 }
2128
2129 module_init(raid5_init);
2130 module_exit(raid5_exit);
2131 MODULE_LICENSE("GPL");
2132 MODULE_ALIAS("md-personality-4"); /* RAID5 */