drivers/md/raid10.c

   1 /*
   2  * raid10.c : Multiple Devices driver for Linux
   3  *
   4  * Copyright (C) 2000-2004 Neil Brown
   5  *
   6  * RAID-10 support for md.
   7  *
   8  * Base on code in raid1.c.  See raid1.c for further copyright information.
   9  *
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2, or (at your option)
  14  * any later version.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * (for example /usr/src/linux/COPYING); if not, write to the Free
  18  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  */
  20
  21 #include <linux/slab.h>
  22 #include <linux/delay.h>
  23 #include <linux/blkdev.h>
  24 #include <linux/module.h>
  25 #include <linux/seq_file.h>
  26 #include <linux/ratelimit.h>
  27 #include <linux/kthread.h>
  28 #include "md.h"
  29 #include "raid10.h"
  30 #include "raid0.h"
  31 #include "bitmap.h"
  32
  33 /*
  34  * RAID10 provides a combination of RAID0 and RAID1 functionality.
  35  * The layout of data is defined by
  36  *    chunk_size
  37  *    raid_disks
  38  *    near_copies (stored in low byte of layout)
  39  *    far_copies (stored in second byte of layout)
  40  *    far_offset (stored in bit 16 of layout )
  41  *    use_far_sets (stored in bit 17 of layout )
  42  *
  43  * The data to be stored is divided into chunks using chunksize.  Each device
  44  * is divided into far_copies sections.   In each section, chunks are laid out
  45  * in a style similar to raid0, but near_copies copies of each chunk is stored
  46  * (each on a different drive).  The starting device for each section is offset
  47  * near_copies from the starting device of the previous section.  Thus there
  48  * are (near_copies * far_copies) of each chunk, and each is on a different
  49  * drive.  near_copies and far_copies must be at least one, and their product
  50  * is at most raid_disks.
  51  *
  52  * If far_offset is true, then the far_copies are handled a bit differently.
  53  * The copies are still in different stripes, but instead of being very far
  54  * apart on disk, there are adjacent stripes.
  55  *
  56  * The far and offset algorithms are handled slightly differently if
  57  * 'use_far_sets' is true.  In this case, the array's devices are grouped into
  58  * sets that are (near_copies * far_copies) in size.  The far copied stripes
  59  * are still shifted by 'near_copies' devices, but this shifting stays confined
  60  * to the set rather than the entire array.  This is done to improve the number
  61  * of device combinations that can fail without causing the array to fail.
  62  * Example 'far' algorithm w/o 'use_far_sets' (each letter represents a chunk
  63  * on a device):
  64  *    A B C D    A B C D E
  65  *      ...         ...
  66  *    D A B C    E A B C D
  67  * Example 'far' algorithm w/ 'use_far_sets' enabled (sets illustrated w/ []'s):
  68  *    [A B] [C D]    [A B] [C D E]
  69  *    |...| |...|    |...| | ... |
  70  *    [B A] [D C]    [B A] [E C D]
  71  */
  72
  73 /*
  74  * Number of guaranteed r10bios in case of extreme VM load:
  75  */
  76 #define NR_RAID10_BIOS 256
  77
  78 /* when we get a read error on a read-only array, we redirect to another
  79  * device without failing the first device, or trying to over-write to
  80  * correct the read error.  To keep track of bad blocks on a per-bio
  81  * level, we store IO_BLOCKED in the appropriate 'bios' pointer
  82  */
  83 #define IO_BLOCKED ((struct bio *)1)
  84 /* When we successfully write to a known bad-block, we need to remove the
  85  * bad-block marking which must be done from process context.  So we record
  86  * the success by setting devs[n].bio to IO_MADE_GOOD
  87  */
  88 #define IO_MADE_GOOD ((struct bio *)2)
  89
  90 #define BIO_SPECIAL(bio) ((unsigned long)bio <= 2)
  91
  92 /* When there are this many requests queued to be written by
  93  * the raid10 thread, we become 'congested' to provide back-pressure
  94  * for writeback.
  95  */
  96 static int max_queued_requests = 1024;
  97
  98 static void allow_barrier(struct r10conf *conf);
  99 static void lower_barrier(struct r10conf *conf);
 100 static int _enough(struct r10conf *conf, int previous, int ignore);
 101 static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr,
 102                                 int *skipped);
 103 static void reshape_request_write(struct mddev *mddev, struct r10bio *r10_bio);
 104 static void end_reshape_write(struct bio *bio, int error);
 105 static void end_reshape(struct r10conf *conf);
 106
 107 static void * r10bio_pool_alloc(gfp_t gfp_flags, void *data)
 108 {
 109         struct r10conf *conf = data;
 110         int size = offsetof(struct r10bio, devs[conf->copies]);
 111
 112         /* allocate a r10bio with room for raid_disks entries in the
 113          * bios array */
 114         return kzalloc(size, gfp_flags);
 115 }
 116
 117 static void r10bio_pool_free(void *r10_bio, void *data)
 118 {
 119         kfree(r10_bio);
 120 }
 121
 122 /* Maximum size of each resync request */
 123 #define RESYNC_BLOCK_SIZE (64*1024)
 124 #define RESYNC_PAGES ((RESYNC_BLOCK_SIZE + PAGE_SIZE-1) / PAGE_SIZE)
 125 /* amount of memory to reserve for resync requests */
 126 #define RESYNC_WINDOW (1024*1024)
 127 /* maximum number of concurrent requests, memory permitting */
 128 #define RESYNC_DEPTH (32*1024*1024/RESYNC_BLOCK_SIZE)
 129
 130 /*
 131  * When performing a resync, we need to read and compare, so
 132  * we need as many pages are there are copies.
 133  * When performing a recovery, we need 2 bios, one for read,
 134  * one for write (we recover only one drive per r10buf)
 135  *
 136  */
 137 static void * r10buf_pool_alloc(gfp_t gfp_flags, void *data)
 138 {
 139         struct r10conf *conf = data;
 140         struct page *page;
 141         struct r10bio *r10_bio;
 142         struct bio *bio;
 143         int i, j;
 144         int nalloc;
 145
 146         r10_bio = r10bio_pool_alloc(gfp_flags, conf);
 147         if (!r10_bio)
 148                 return NULL;
 149
 150         if (test_bit(MD_RECOVERY_SYNC, &conf->mddev->recovery) ||
 151             test_bit(MD_RECOVERY_RESHAPE, &conf->mddev->recovery))
 152                 nalloc = conf->copies; /* resync */
 153         else
 154                 nalloc = 2; /* recovery */
 155
 156         /*
 157          * Allocate bios.
 158          */
 159         for (j = nalloc ; j-- ; ) {
 160                 bio = bio_kmalloc(gfp_flags, RESYNC_PAGES);
 161                 if (!bio)
 162                         goto out_free_bio;
 163                 r10_bio->devs[j].bio = bio;
 164                 if (!conf->have_replacement)
 165                         continue;
 166                 bio = bio_kmalloc(gfp_flags, RESYNC_PAGES);
 167                 if (!bio)
 168                         goto out_free_bio;
 169                 r10_bio->devs[j].repl_bio = bio;
 170         }
 171         /*
 172          * Allocate RESYNC_PAGES data pages and attach them
 173          * where needed.
 174          */
 175         for (j = 0 ; j < nalloc; j++) {
 176                 struct bio *rbio = r10_bio->devs[j].repl_bio;
 177                 bio = r10_bio->devs[j].bio;
 178                 for (i = 0; i < RESYNC_PAGES; i++) {
 179                         if (j > 0 && !test_bit(MD_RECOVERY_SYNC,
 180                                                &conf->mddev->recovery)) {
 181                                 /* we can share bv_page's during recovery
 182                                  * and reshape */
 183                                 struct bio *rbio = r10_bio->devs[0].bio;
 184                                 page = rbio->bi_io_vec[i].bv_page;
 185                                 get_page(page);
 186                         } else
 187                                 page = alloc_page(gfp_flags);
 188                         if (unlikely(!page))
 189                                 goto out_free_pages;
 190
 191                         bio->bi_io_vec[i].bv_page = page;
 192                         if (rbio)
 193                                 rbio->bi_io_vec[i].bv_page = page;
 194                 }
 195         }
 196
 197         return r10_bio;
 198
 199 out_free_pages:
 200         for ( ; i > 0 ; i--)
 201                 safe_put_page(bio->bi_io_vec[i-1].bv_page);
 202         while (j--)
 203                 for (i = 0; i < RESYNC_PAGES ; i++)
 204                         safe_put_page(r10_bio->devs[j].bio->bi_io_vec[i].bv_page);
 205         j = 0;
 206 out_free_bio:
 207         for ( ; j < nalloc; j++) {
 208                 if (r10_bio->devs[j].bio)
 209                         bio_put(r10_bio->devs[j].bio);
 210                 if (r10_bio->devs[j].repl_bio)
 211                         bio_put(r10_bio->devs[j].repl_bio);
 212         }
 213         r10bio_pool_free(r10_bio, conf);
 214         return NULL;
 215 }
 216
 217 static void r10buf_pool_free(void *__r10_bio, void *data)
 218 {
 219         int i;
 220         struct r10conf *conf = data;
 221         struct r10bio *r10bio = __r10_bio;
 222         int j;
 223
 224         for (j=0; j < conf->copies; j++) {
 225                 struct bio *bio = r10bio->devs[j].bio;
 226                 if (bio) {
 227                         for (i = 0; i < RESYNC_PAGES; i++) {
 228                                 safe_put_page(bio->bi_io_vec[i].bv_page);
 229                                 bio->bi_io_vec[i].bv_page = NULL;
 230                         }
 231                         bio_put(bio);
 232                 }
 233                 bio = r10bio->devs[j].repl_bio;
 234                 if (bio)
 235                         bio_put(bio);
 236         }
 237         r10bio_pool_free(r10bio, conf);
 238 }
 239
 240 static void put_all_bios(struct r10conf *conf, struct r10bio *r10_bio)
 241 {
 242         int i;
 243
 244         for (i = 0; i < conf->copies; i++) {
 245                 struct bio **bio = & r10_bio->devs[i].bio;
 246                 if (!BIO_SPECIAL(*bio))
 247                         bio_put(*bio);
 248                 *bio = NULL;
 249                 bio = &r10_bio->devs[i].repl_bio;
 250                 if (r10_bio->read_slot < 0 && !BIO_SPECIAL(*bio))
 251                         bio_put(*bio);
 252                 *bio = NULL;
 253         }
 254 }
 255
 256 static void free_r10bio(struct r10bio *r10_bio)
 257 {
 258         struct r10conf *conf = r10_bio->mddev->private;
 259
 260         put_all_bios(conf, r10_bio);
 261         mempool_free(r10_bio, conf->r10bio_pool);
 262 }
 263
 264 static void put_buf(struct r10bio *r10_bio)
 265 {
 266         struct r10conf *conf = r10_bio->mddev->private;
 267
 268         mempool_free(r10_bio, conf->r10buf_pool);
 269
 270         lower_barrier(conf);
 271 }
 272
 273 static void reschedule_retry(struct r10bio *r10_bio)
 274 {
 275         unsigned long flags;
 276         struct mddev *mddev = r10_bio->mddev;
 277         struct r10conf *conf = mddev->private;
 278
 279         spin_lock_irqsave(&conf->device_lock, flags);
 280         list_add(&r10_bio->retry_list, &conf->retry_list);
 281         conf->nr_queued ++;
 282         spin_unlock_irqrestore(&conf->device_lock, flags);
 283
 284         /* wake up frozen array... */
 285         wake_up(&conf->wait_barrier);
 286
 287         md_wakeup_thread(mddev->thread);
 288 }
 289
 290 /*
 291  * raid_end_bio_io() is called when we have finished servicing a mirrored
 292  * operation and are ready to return a success/failure code to the buffer
 293  * cache layer.
 294  */
 295 static void raid_end_bio_io(struct r10bio *r10_bio)
 296 {
 297         struct bio *bio = r10_bio->master_bio;
 298         int done;
 299         struct r10conf *conf = r10_bio->mddev->private;
 300
 301         if (bio->bi_phys_segments) {
 302                 unsigned long flags;
 303                 spin_lock_irqsave(&conf->device_lock, flags);
 304                 bio->bi_phys_segments--;
 305                 done = (bio->bi_phys_segments == 0);
 306                 spin_unlock_irqrestore(&conf->device_lock, flags);
 307         } else
 308                 done = 1;
 309         if (!test_bit(R10BIO_Uptodate, &r10_bio->state))
 310                 clear_bit(BIO_UPTODATE, &bio->bi_flags);
 311         if (done) {
 312                 bio_endio(bio, 0);
 313                 /*
 314                  * Wake up any possible resync thread that waits for the device
 315                  * to go idle.
 316                  */
 317                 allow_barrier(conf);
 318         }
 319         free_r10bio(r10_bio);
 320 }
 321
 322 /*
 323  * Update disk head position estimator based on IRQ completion info.
 324  */
 325 static inline void update_head_pos(int slot, struct r10bio *r10_bio)
 326 {
 327         struct r10conf *conf = r10_bio->mddev->private;
 328
 329         conf->mirrors[r10_bio->devs[slot].devnum].head_position =
 330                 r10_bio->devs[slot].addr + (r10_bio->sectors);
 331 }
 332
 333 /*
 334  * Find the disk number which triggered given bio
 335  */
 336 static int find_bio_disk(struct r10conf *conf, struct r10bio *r10_bio,
 337                          struct bio *bio, int *slotp, int *replp)
 338 {
 339         int slot;
 340         int repl = 0;
 341
 342         for (slot = 0; slot < conf->copies; slot++) {
 343                 if (r10_bio->devs[slot].bio == bio)
 344                         break;
 345                 if (r10_bio->devs[slot].repl_bio == bio) {
 346                         repl = 1;
 347                         break;
 348                 }
 349         }
 350
 351         BUG_ON(slot == conf->copies);
 352         update_head_pos(slot, r10_bio);
 353
 354         if (slotp)
 355                 *slotp = slot;
 356         if (replp)
 357                 *replp = repl;
 358         return r10_bio->devs[slot].devnum;
 359 }
 360
 361 static void raid10_end_read_request(struct bio *bio, int error)
 362 {
 363         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 364         struct r10bio *r10_bio = bio->bi_private;
 365         int slot, dev;
 366         struct md_rdev *rdev;
 367         struct r10conf *conf = r10_bio->mddev->private;
 368
 369
 370         slot = r10_bio->read_slot;
 371         dev = r10_bio->devs[slot].devnum;
 372         rdev = r10_bio->devs[slot].rdev;
 373         /*
 374          * this branch is our 'one mirror IO has finished' event handler:
 375          */
 376         update_head_pos(slot, r10_bio);
 377
 378         if (uptodate) {
 379                 /*
 380                  * Set R10BIO_Uptodate in our master bio, so that
 381                  * we will return a good error code to the higher
 382                  * levels even if IO on some other mirrored buffer fails.
 383                  *
 384                  * The 'master' represents the composite IO operation to
 385                  * user-side. So if something waits for IO, then it will
 386                  * wait for the 'master' bio.
 387                  */
 388                 set_bit(R10BIO_Uptodate, &r10_bio->state);
 389         } else {
 390                 /* If all other devices that store this block have
 391                  * failed, we want to return the error upwards rather
 392                  * than fail the last device.  Here we redefine
 393                  * "uptodate" to mean "Don't want to retry"
 394                  */
 395                 if (!_enough(conf, test_bit(R10BIO_Previous, &r10_bio->state),
 396                              rdev->raid_disk))
 397                         uptodate = 1;
 398         }
 399         if (uptodate) {
 400                 raid_end_bio_io(r10_bio);
 401                 rdev_dec_pending(rdev, conf->mddev);
 402         } else {
 403                 /*
 404                  * oops, read error - keep the refcount on the rdev
 405                  */
 406                 char b[BDEVNAME_SIZE];
 407                 printk_ratelimited(KERN_ERR
 408                                    "md/raid10:%s: %s: rescheduling sector %llu\n",
 409                                    mdname(conf->mddev),
 410                                    bdevname(rdev->bdev, b),
 411                                    (unsigned long long)r10_bio->sector);
 412                 set_bit(R10BIO_ReadError, &r10_bio->state);
 413                 reschedule_retry(r10_bio);
 414         }
 415 }
 416
 417 static void close_write(struct r10bio *r10_bio)
 418 {
 419         /* clear the bitmap if all writes complete successfully */
 420         bitmap_endwrite(r10_bio->mddev->bitmap, r10_bio->sector,
 421                         r10_bio->sectors,
 422                         !test_bit(R10BIO_Degraded, &r10_bio->state),
 423                         0);
 424         md_write_end(r10_bio->mddev);
 425 }
 426
 427 static void one_write_done(struct r10bio *r10_bio)
 428 {
 429         if (atomic_dec_and_test(&r10_bio->remaining)) {
 430                 if (test_bit(R10BIO_WriteError, &r10_bio->state))
 431                         reschedule_retry(r10_bio);
 432                 else {
 433                         close_write(r10_bio);
 434                         if (test_bit(R10BIO_MadeGood, &r10_bio->state))
 435                                 reschedule_retry(r10_bio);
 436                         else
 437                                 raid_end_bio_io(r10_bio);
 438                 }
 439         }
 440 }
 441
 442 static void raid10_end_write_request(struct bio *bio, int error)
 443 {
 444         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 445         struct r10bio *r10_bio = bio->bi_private;
 446         int dev;
 447         int dec_rdev = 1;
 448         struct r10conf *conf = r10_bio->mddev->private;
 449         int slot, repl;
 450         struct md_rdev *rdev = NULL;
 451
 452         dev = find_bio_disk(conf, r10_bio, bio, &slot, &repl);
 453
 454         if (repl)
 455                 rdev = conf->mirrors[dev].replacement;
 456         if (!rdev) {
 457                 smp_rmb();
 458                 repl = 0;
 459                 rdev = conf->mirrors[dev].rdev;
 460         }
 461         /*
 462          * this branch is our 'one mirror IO has finished' event handler:
 463          */
 464         if (!uptodate) {
 465                 if (repl)
 466                         /* Never record new bad blocks to replacement,
 467                          * just fail it.
 468                          */
 469                         md_error(rdev->mddev, rdev);
 470                 else {
 471                         set_bit(WriteErrorSeen, &rdev->flags);
 472                         if (!test_and_set_bit(WantReplacement, &rdev->flags))
 473                                 set_bit(MD_RECOVERY_NEEDED,
 474                                         &rdev->mddev->recovery);
 475                         set_bit(R10BIO_WriteError, &r10_bio->state);
 476                         dec_rdev = 0;
 477                 }
 478         } else {
 479                 /*
 480                  * Set R10BIO_Uptodate in our master bio, so that
 481                  * we will return a good error code for to the higher
 482                  * levels even if IO on some other mirrored buffer fails.
 483                  *
 484                  * The 'master' represents the composite IO operation to
 485                  * user-side. So if something waits for IO, then it will
 486                  * wait for the 'master' bio.
 487                  */
 488                 sector_t first_bad;
 489                 int bad_sectors;
 490
 491                 /*
 492                  * Do not set R10BIO_Uptodate if the current device is
 493                  * rebuilding or Faulty. This is because we cannot use
 494                  * such device for properly reading the data back (we could
 495                  * potentially use it, if the current write would have felt
 496                  * before rdev->recovery_offset, but for simplicity we don't
 497                  * check this here.
 498                  */
 499                 if (test_bit(In_sync, &rdev->flags) &&
 500                     !test_bit(Faulty, &rdev->flags))
 501                         set_bit(R10BIO_Uptodate, &r10_bio->state);
 502
 503                 /* Maybe we can clear some bad blocks. */
 504                 if (is_badblock(rdev,
 505                                 r10_bio->devs[slot].addr,
 506                                 r10_bio->sectors,
 507                                 &first_bad, &bad_sectors)) {
 508                         bio_put(bio);
 509                         if (repl)
 510                                 r10_bio->devs[slot].repl_bio = IO_MADE_GOOD;
 511                         else
 512                                 r10_bio->devs[slot].bio = IO_MADE_GOOD;
 513                         dec_rdev = 0;
 514                         set_bit(R10BIO_MadeGood, &r10_bio->state);
 515                 }
 516         }
 517
 518         /*
 519          *
 520          * Let's see if all mirrored write operations have finished
 521          * already.
 522          */
 523         one_write_done(r10_bio);
 524         if (dec_rdev)
 525                 rdev_dec_pending(rdev, conf->mddev);
 526 }
 527
 528 /*
 529  * RAID10 layout manager
 530  * As well as the chunksize and raid_disks count, there are two
 531  * parameters: near_copies and far_copies.
 532  * near_copies * far_copies must be <= raid_disks.
 533  * Normally one of these will be 1.
 534  * If both are 1, we get raid0.
 535  * If near_copies == raid_disks, we get raid1.
 536  *
 537  * Chunks are laid out in raid0 style with near_copies copies of the
 538  * first chunk, followed by near_copies copies of the next chunk and
 539  * so on.
 540  * If far_copies > 1, then after 1/far_copies of the array has been assigned
 541  * as described above, we start again with a device offset of near_copies.
 542  * So we effectively have another copy of the whole array further down all
 543  * the drives, but with blocks on different drives.
 544  * With this layout, and block is never stored twice on the one device.
 545  *
 546  * raid10_find_phys finds the sector offset of a given virtual sector
 547  * on each device that it is on.
 548  *
 549  * raid10_find_virt does the reverse mapping, from a device and a
 550  * sector offset to a virtual address
 551  */
 552
 553 static void __raid10_find_phys(struct geom *geo, struct r10bio *r10bio)
 554 {
 555         int n,f;
 556         sector_t sector;
 557         sector_t chunk;
 558         sector_t stripe;
 559         int dev;
 560         int slot = 0;
 561         int last_far_set_start, last_far_set_size;
 562
 563         last_far_set_start = (geo->raid_disks / geo->far_set_size) - 1;
 564         last_far_set_start *= geo->far_set_size;
 565
 566         last_far_set_size = geo->far_set_size;
 567         last_far_set_size += (geo->raid_disks % geo->far_set_size);
 568
 569         /* now calculate first sector/dev */
 570         chunk = r10bio->sector >> geo->chunk_shift;
 571         sector = r10bio->sector & geo->chunk_mask;
 572
 573         chunk *= geo->near_copies;
 574         stripe = chunk;
 575         dev = sector_div(stripe, geo->raid_disks);
 576         if (geo->far_offset)
 577                 stripe *= geo->far_copies;
 578
 579         sector += stripe << geo->chunk_shift;
 580
 581         /* and calculate all the others */
 582         for (n = 0; n < geo->near_copies; n++) {
 583                 int d = dev;
 584                 int set;
 585                 sector_t s = sector;
 586                 r10bio->devs[slot].devnum = d;
 587                 r10bio->devs[slot].addr = s;
 588                 slot++;
 589
 590                 for (f = 1; f < geo->far_copies; f++) {
 591                         set = d / geo->far_set_size;
 592                         d += geo->near_copies;
 593
 594                         if ((geo->raid_disks % geo->far_set_size) &&
 595                             (d > last_far_set_start)) {
 596                                 d -= last_far_set_start;
 597                                 d %= last_far_set_size;
 598                                 d += last_far_set_start;
 599                         } else {
 600                                 d %= geo->far_set_size;
 601                                 d += geo->far_set_size * set;
 602                         }
 603                         s += geo->stride;
 604                         r10bio->devs[slot].devnum = d;
 605                         r10bio->devs[slot].addr = s;
 606                         slot++;
 607                 }
 608                 dev++;
 609                 if (dev >= geo->raid_disks) {
 610                         dev = 0;
 611                         sector += (geo->chunk_mask + 1);
 612                 }
 613         }
 614 }
 615
 616 static void raid10_find_phys(struct r10conf *conf, struct r10bio *r10bio)
 617 {
 618         struct geom *geo = &conf->geo;
 619
 620         if (conf->reshape_progress != MaxSector &&
 621             ((r10bio->sector >= conf->reshape_progress) !=
 622              conf->mddev->reshape_backwards)) {
 623                 set_bit(R10BIO_Previous, &r10bio->state);
 624                 geo = &conf->prev;
 625         } else
 626                 clear_bit(R10BIO_Previous, &r10bio->state);
 627
 628         __raid10_find_phys(geo, r10bio);
 629 }
 630
 631 static sector_t raid10_find_virt(struct r10conf *conf, sector_t sector, int dev)
 632 {
 633         sector_t offset, chunk, vchunk;
 634         /* Never use conf->prev as this is only called during resync
 635          * or recovery, so reshape isn't happening
 636          */
 637         struct geom *geo = &conf->geo;
 638         int far_set_start = (dev / geo->far_set_size) * geo->far_set_size;
 639         int far_set_size = geo->far_set_size;
 640         int last_far_set_start;
 641
 642         if (geo->raid_disks % geo->far_set_size) {
 643                 last_far_set_start = (geo->raid_disks / geo->far_set_size) - 1;
 644                 last_far_set_start *= geo->far_set_size;
 645
 646                 if (dev >= last_far_set_start) {
 647                         far_set_size = geo->far_set_size;
 648                         far_set_size += (geo->raid_disks % geo->far_set_size);
 649                         far_set_start = last_far_set_start;
 650                 }
 651         }
 652
 653         offset = sector & geo->chunk_mask;
 654         if (geo->far_offset) {
 655                 int fc;
 656                 chunk = sector >> geo->chunk_shift;
 657                 fc = sector_div(chunk, geo->far_copies);
 658                 dev -= fc * geo->near_copies;
 659                 if (dev < far_set_start)
 660                         dev += far_set_size;
 661         } else {
 662                 while (sector >= geo->stride) {
 663                         sector -= geo->stride;
 664                         if (dev < (geo->near_copies + far_set_start))
 665                                 dev += far_set_size - geo->near_copies;
 666                         else
 667                                 dev -= geo->near_copies;
 668                 }
 669                 chunk = sector >> geo->chunk_shift;
 670         }
 671         vchunk = chunk * geo->raid_disks + dev;
 672         sector_div(vchunk, geo->near_copies);
 673         return (vchunk << geo->chunk_shift) + offset;
 674 }
 675
 676 /**
 677  *      raid10_mergeable_bvec -- tell bio layer if a two requests can be merged
 678  *      @q: request queue
 679  *      @bvm: properties of new bio
 680  *      @biovec: the request that could be merged to it.
 681  *
 682  *      Return amount of bytes we can accept at this offset
 683  *      This requires checking for end-of-chunk if near_copies != raid_disks,
 684  *      and for subordinate merge_bvec_fns if merge_check_needed.
 685  */
 686 static int raid10_mergeable_bvec(struct request_queue *q,
 687                                  struct bvec_merge_data *bvm,
 688                                  struct bio_vec *biovec)
 689 {
 690         struct mddev *mddev = q->queuedata;
 691         struct r10conf *conf = mddev->private;
 692         sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
 693         int max;
 694         unsigned int chunk_sectors;
 695         unsigned int bio_sectors = bvm->bi_size >> 9;
 696         struct geom *geo = &conf->geo;
 697
 698         chunk_sectors = (conf->geo.chunk_mask & conf->prev.chunk_mask) + 1;
 699         if (conf->reshape_progress != MaxSector &&
 700             ((sector >= conf->reshape_progress) !=
 701              conf->mddev->reshape_backwards))
 702                 geo = &conf->prev;
 703
 704         if (geo->near_copies < geo->raid_disks) {
 705                 max = (chunk_sectors - ((sector & (chunk_sectors - 1))
 706                                         + bio_sectors)) << 9;
 707                 if (max < 0)
 708                         /* bio_add cannot handle a negative return */
 709                         max = 0;
 710                 if (max <= biovec->bv_len && bio_sectors == 0)
 711                         return biovec->bv_len;
 712         } else
 713                 max = biovec->bv_len;
 714
 715         if (mddev->merge_check_needed) {
 716                 struct {
 717                         struct r10bio r10_bio;
 718                         struct r10dev devs[conf->copies];
 719                 } on_stack;
 720                 struct r10bio *r10_bio = &on_stack.r10_bio;
 721                 int s;
 722                 if (conf->reshape_progress != MaxSector) {
 723                         /* Cannot give any guidance during reshape */
 724                         if (max <= biovec->bv_len && bio_sectors == 0)
 725                                 return biovec->bv_len;
 726                         return 0;
 727                 }
 728                 r10_bio->sector = sector;
 729                 raid10_find_phys(conf, r10_bio);
 730                 rcu_read_lock();
 731                 for (s = 0; s < conf->copies; s++) {
 732                         int disk = r10_bio->devs[s].devnum;
 733                         struct md_rdev *rdev = rcu_dereference(
 734                                 conf->mirrors[disk].rdev);
 735                         if (rdev && !test_bit(Faulty, &rdev->flags)) {
 736                                 struct request_queue *q =
 737                                         bdev_get_queue(rdev->bdev);
 738                                 if (q->merge_bvec_fn) {
 739                                         bvm->bi_sector = r10_bio->devs[s].addr
 740                                                 + rdev->data_offset;
 741                                         bvm->bi_bdev = rdev->bdev;
 742                                         max = min(max, q->merge_bvec_fn(
 743                                                           q, bvm, biovec));
 744                                 }
 745                         }
 746                         rdev = rcu_dereference(conf->mirrors[disk].replacement);
 747                         if (rdev && !test_bit(Faulty, &rdev->flags)) {
 748                                 struct request_queue *q =
 749                                         bdev_get_queue(rdev->bdev);
 750                                 if (q->merge_bvec_fn) {
 751                                         bvm->bi_sector = r10_bio->devs[s].addr
 752                                                 + rdev->data_offset;
 753                                         bvm->bi_bdev = rdev->bdev;
 754                                         max = min(max, q->merge_bvec_fn(
 755                                                           q, bvm, biovec));
 756                                 }
 757                         }
 758                 }
 759                 rcu_read_unlock();
 760         }
 761         return max;
 762 }
 763
 764 /*
 765  * This routine returns the disk from which the requested read should
 766  * be done. There is a per-array 'next expected sequential IO' sector
 767  * number - if this matches on the next IO then we use the last disk.
 768  * There is also a per-disk 'last know head position' sector that is
 769  * maintained from IRQ contexts, both the normal and the resync IO
 770  * completion handlers update this position correctly. If there is no
 771  * perfect sequential match then we pick the disk whose head is closest.
 772  *
 773  * If there are 2 mirrors in the same 2 devices, performance degrades
 774  * because position is mirror, not device based.
 775  *
 776  * The rdev for the device selected will have nr_pending incremented.
 777  */
 778
 779 /*
 780  * FIXME: possibly should rethink readbalancing and do it differently
 781  * depending on near_copies / far_copies geometry.
 782  */
 783 static struct md_rdev *read_balance(struct r10conf *conf,
 784                                     struct r10bio *r10_bio,
 785                                     int *max_sectors)
 786 {
 787         const sector_t this_sector = r10_bio->sector;
 788         int disk, slot;
 789         int sectors = r10_bio->sectors;
 790         int best_good_sectors;
 791         sector_t new_distance, best_dist;
 792         struct md_rdev *best_rdev, *rdev = NULL;
 793         int do_balance;
 794         int best_slot;
 795         struct geom *geo = &conf->geo;
 796
 797         raid10_find_phys(conf, r10_bio);
 798         rcu_read_lock();
 799 retry:
 800         sectors = r10_bio->sectors;
 801         best_slot = -1;
 802         best_rdev = NULL;
 803         best_dist = MaxSector;
 804         best_good_sectors = 0;
 805         do_balance = 1;
 806         /*
 807          * Check if we can balance. We can balance on the whole
 808          * device if no resync is going on (recovery is ok), or below
 809          * the resync window. We take the first readable disk when
 810          * above the resync window.
 811          */
 812         if (conf->mddev->recovery_cp < MaxSector
 813             && (this_sector + sectors >= conf->next_resync))
 814                 do_balance = 0;
 815
 816         for (slot = 0; slot < conf->copies ; slot++) {
 817                 sector_t first_bad;
 818                 int bad_sectors;
 819                 sector_t dev_sector;
 820
 821                 if (r10_bio->devs[slot].bio == IO_BLOCKED)
 822                         continue;
 823                 disk = r10_bio->devs[slot].devnum;
 824                 rdev = rcu_dereference(conf->mirrors[disk].replacement);
 825                 if (rdev == NULL || test_bit(Faulty, &rdev->flags) ||
 826                     test_bit(Unmerged, &rdev->flags) ||
 827                     r10_bio->devs[slot].addr + sectors > rdev->recovery_offset)
 828                         rdev = rcu_dereference(conf->mirrors[disk].rdev);
 829                 if (rdev == NULL ||
 830                     test_bit(Faulty, &rdev->flags) ||
 831                     test_bit(Unmerged, &rdev->flags))
 832                         continue;
 833                 if (!test_bit(In_sync, &rdev->flags) &&
 834                     r10_bio->devs[slot].addr + sectors > rdev->recovery_offset)
 835                         continue;
 836
 837                 dev_sector = r10_bio->devs[slot].addr;
 838                 if (is_badblock(rdev, dev_sector, sectors,
 839                                 &first_bad, &bad_sectors)) {
 840                         if (best_dist < MaxSector)
 841                                 /* Already have a better slot */
 842                                 continue;
 843                         if (first_bad <= dev_sector) {
 844                                 /* Cannot read here.  If this is the
 845                                  * 'primary' device, then we must not read
 846                                  * beyond 'bad_sectors' from another device.
 847                                  */
 848                                 bad_sectors -= (dev_sector - first_bad);
 849                                 if (!do_balance && sectors > bad_sectors)
 850                                         sectors = bad_sectors;
 851                                 if (best_good_sectors > sectors)
 852                                         best_good_sectors = sectors;
 853                         } else {
 854                                 sector_t good_sectors =
 855                                         first_bad - dev_sector;
 856                                 if (good_sectors > best_good_sectors) {
 857                                         best_good_sectors = good_sectors;
 858                                         best_slot = slot;
 859                                         best_rdev = rdev;
 860                                 }
 861                                 if (!do_balance)
 862                                         /* Must read from here */
 863                                         break;
 864                         }
 865                         continue;
 866                 } else
 867                         best_good_sectors = sectors;
 868
 869                 if (!do_balance)
 870                         break;
 871
 872                 /* This optimisation is debatable, and completely destroys
 873                  * sequential read speed for 'far copies' arrays.  So only
 874                  * keep it for 'near' arrays, and review those later.
 875                  */
 876                 if (geo->near_copies > 1 && !atomic_read(&rdev->nr_pending))
 877                         break;
 878
 879                 /* for far > 1 always use the lowest address */
 880                 if (geo->far_copies > 1)
 881                         new_distance = r10_bio->devs[slot].addr;
 882                 else
 883                         new_distance = abs(r10_bio->devs[slot].addr -
 884                                            conf->mirrors[disk].head_position);
 885                 if (new_distance < best_dist) {
 886                         best_dist = new_distance;
 887                         best_slot = slot;
 888                         best_rdev = rdev;
 889                 }
 890         }
 891         if (slot >= conf->copies) {
 892                 slot = best_slot;
 893                 rdev = best_rdev;
 894         }
 895
 896         if (slot >= 0) {
 897                 atomic_inc(&rdev->nr_pending);
 898                 if (test_bit(Faulty, &rdev->flags)) {
 899                         /* Cannot risk returning a device that failed
 900                          * before we inc'ed nr_pending
 901                          */
 902                         rdev_dec_pending(rdev, conf->mddev);
 903                         goto retry;
 904                 }
 905                 r10_bio->read_slot = slot;
 906         } else
 907                 rdev = NULL;
 908         rcu_read_unlock();
 909         *max_sectors = best_good_sectors;
 910
 911         return rdev;
 912 }
 913
 914 int md_raid10_congested(struct mddev *mddev, int bits)
 915 {
 916         struct r10conf *conf = mddev->private;
 917         int i, ret = 0;
 918
 919         if ((bits & (1 << BDI_async_congested)) &&
 920             conf->pending_count >= max_queued_requests)
 921                 return 1;
 922
 923         rcu_read_lock();
 924         for (i = 0;
 925              (i < conf->geo.raid_disks || i < conf->prev.raid_disks)
 926                      && ret == 0;
 927              i++) {
 928                 struct md_rdev *rdev = rcu_dereference(conf->mirrors[i].rdev);
 929                 if (rdev && !test_bit(Faulty, &rdev->flags)) {
 930                         struct request_queue *q = bdev_get_queue(rdev->bdev);
 931
 932                         ret |= bdi_congested(&q->backing_dev_info, bits);
 933                 }
 934         }
 935         rcu_read_unlock();
 936         return ret;
 937 }
 938 EXPORT_SYMBOL_GPL(md_raid10_congested);
 939
 940 static int raid10_congested(void *data, int bits)
 941 {
 942         struct mddev *mddev = data;
 943
 944         return mddev_congested(mddev, bits) ||
 945                 md_raid10_congested(mddev, bits);
 946 }
 947
 948 static void flush_pending_writes(struct r10conf *conf)
 949 {
 950         /* Any writes that have been queued but are awaiting
 951          * bitmap updates get flushed here.
 952          */
 953         spin_lock_irq(&conf->device_lock);
 954
 955         if (conf->pending_bio_list.head) {
 956                 struct bio *bio;
 957                 bio = bio_list_get(&conf->pending_bio_list);
 958                 conf->pending_count = 0;
 959                 spin_unlock_irq(&conf->device_lock);
 960                 /* flush any pending bitmap writes to disk
 961                  * before proceeding w/ I/O */
 962                 bitmap_unplug(conf->mddev->bitmap);
 963                 wake_up(&conf->wait_barrier);
 964
 965                 while (bio) { /* submit pending writes */
 966                         struct bio *next = bio->bi_next;
 967                         bio->bi_next = NULL;
 968                         if (unlikely((bio->bi_rw & REQ_DISCARD) &&
 969                             !blk_queue_discard(bdev_get_queue(bio->bi_bdev))))
 970                                 /* Just ignore it */
 971                                 bio_endio(bio, 0);
 972                         else
 973                                 generic_make_request(bio);
 974                         bio = next;
 975                 }
 976         } else
 977                 spin_unlock_irq(&conf->device_lock);
 978 }
 979
 980 /* Barriers....
 981  * Sometimes we need to suspend IO while we do something else,
 982  * either some resync/recovery, or reconfigure the array.
 983  * To do this we raise a 'barrier'.
 984  * The 'barrier' is a counter that can be raised multiple times
 985  * to count how many activities are happening which preclude
 986  * normal IO.
 987  * We can only raise the barrier if there is no pending IO.
 988  * i.e. if nr_pending == 0.
 989  * We choose only to raise the barrier if no-one is waiting for the
 990  * barrier to go down.  This means that as soon as an IO request
 991  * is ready, no other operations which require a barrier will start
 992  * until the IO request has had a chance.
 993  *
 994  * So: regular IO calls 'wait_barrier'.  When that returns there
 995  *    is no backgroup IO happening,  It must arrange to call
 996  *    allow_barrier when it has finished its IO.
 997  * backgroup IO calls must call raise_barrier.  Once that returns
 998  *    there is no normal IO happeing.  It must arrange to call
 999  *    lower_barrier when the particular background IO completes.
1000  */
1001
1002 static void raise_barrier(struct r10conf *conf, int force)
1003 {
1004         BUG_ON(force && !conf->barrier);
1005         spin_lock_irq(&conf->resync_lock);
1006
1007         /* Wait until no block IO is waiting (unless 'force') */
1008         wait_event_lock_irq(conf->wait_barrier, force || !conf->nr_waiting,
1009                             conf->resync_lock);
1010
1011         /* block any new IO from starting */
1012         conf->barrier++;
1013
1014         /* Now wait for all pending IO to complete */
1015         wait_event_lock_irq(conf->wait_barrier,
1016                             !conf->nr_pending && conf->barrier < RESYNC_DEPTH,
1017                             conf->resync_lock);
1018
1019         spin_unlock_irq(&conf->resync_lock);
1020 }
1021
1022 static void lower_barrier(struct r10conf *conf)
1023 {
1024         unsigned long flags;
1025         spin_lock_irqsave(&conf->resync_lock, flags);
1026         conf->barrier--;
1027         spin_unlock_irqrestore(&conf->resync_lock, flags);
1028         wake_up(&conf->wait_barrier);
1029 }
1030
1031 static void wait_barrier(struct r10conf *conf)
1032 {
1033         spin_lock_irq(&conf->resync_lock);
1034         if (conf->barrier) {
1035                 conf->nr_waiting++;
1036                 /* Wait for the barrier to drop.
1037                  * However if there are already pending
1038                  * requests (preventing the barrier from
1039                  * rising completely), and the
1040                  * pre-process bio queue isn't empty,
1041                  * then don't wait, as we need to empty
1042                  * that queue to get the nr_pending
1043                  * count down.
1044                  */
1045                 wait_event_lock_irq(conf->wait_barrier,
1046                                     !conf->barrier ||
1047                                     (conf->nr_pending &&
1048                                      current->bio_list &&
1049                                      !bio_list_empty(current->bio_list)),
1050                                     conf->resync_lock);
1051                 conf->nr_waiting--;
1052         }
1053         conf->nr_pending++;
1054         spin_unlock_irq(&conf->resync_lock);
1055 }
1056
1057 static void allow_barrier(struct r10conf *conf)
1058 {
1059         unsigned long flags;
1060         spin_lock_irqsave(&conf->resync_lock, flags);
1061         conf->nr_pending--;
1062         spin_unlock_irqrestore(&conf->resync_lock, flags);
1063         wake_up(&conf->wait_barrier);
1064 }
1065
1066 static void freeze_array(struct r10conf *conf, int extra)
1067 {
1068         /* stop syncio and normal IO and wait for everything to
1069          * go quiet.
1070          * We increment barrier and nr_waiting, and then
1071          * wait until nr_pending match nr_queued+extra
1072          * This is called in the context of one normal IO request
1073          * that has failed. Thus any sync request that might be pending
1074          * will be blocked by nr_pending, and we need to wait for
1075          * pending IO requests to complete or be queued for re-try.
1076          * Thus the number queued (nr_queued) plus this request (extra)
1077          * must match the number of pending IOs (nr_pending) before
1078          * we continue.
1079          */
1080         spin_lock_irq(&conf->resync_lock);
1081         conf->barrier++;
1082         conf->nr_waiting++;
1083         wait_event_lock_irq_cmd(conf->wait_barrier,
1084                                 conf->nr_pending == conf->nr_queued+extra,
1085                                 conf->resync_lock,
1086                                 flush_pending_writes(conf));
1087
1088         spin_unlock_irq(&conf->resync_lock);
1089 }
1090
1091 static void unfreeze_array(struct r10conf *conf)
1092 {
1093         /* reverse the effect of the freeze */
1094         spin_lock_irq(&conf->resync_lock);
1095         conf->barrier--;
1096         conf->nr_waiting--;
1097         wake_up(&conf->wait_barrier);
1098         spin_unlock_irq(&conf->resync_lock);
1099 }
1100
1101 static sector_t choose_data_offset(struct r10bio *r10_bio,
1102                                    struct md_rdev *rdev)
1103 {
1104         if (!test_bit(MD_RECOVERY_RESHAPE, &rdev->mddev->recovery) ||
1105             test_bit(R10BIO_Previous, &r10_bio->state))
1106                 return rdev->data_offset;
1107         else
1108                 return rdev->new_data_offset;
1109 }
1110
1111 struct raid10_plug_cb {
1112         struct blk_plug_cb      cb;
1113         struct bio_list         pending;
1114         int                     pending_cnt;
1115 };
1116
1117 static void raid10_unplug(struct blk_plug_cb *cb, bool from_schedule)
1118 {
1119         struct raid10_plug_cb *plug = container_of(cb, struct raid10_plug_cb,
1120                                                    cb);
1121         struct mddev *mddev = plug->cb.data;
1122         struct r10conf *conf = mddev->private;
1123         struct bio *bio;
1124
1125         if (from_schedule || current->bio_list) {
1126                 spin_lock_irq(&conf->device_lock);
1127                 bio_list_merge(&conf->pending_bio_list, &plug->pending);
1128                 conf->pending_count += plug->pending_cnt;
1129                 spin_unlock_irq(&conf->device_lock);
1130                 wake_up(&conf->wait_barrier);
1131                 md_wakeup_thread(mddev->thread);
1132                 kfree(plug);
1133                 return;
1134         }
1135
1136         /* we aren't scheduling, so we can do the write-out directly. */
1137         bio = bio_list_get(&plug->pending);
1138         bitmap_unplug(mddev->bitmap);
1139         wake_up(&conf->wait_barrier);
1140
1141         while (bio) { /* submit pending writes */
1142                 struct bio *next = bio->bi_next;
1143                 bio->bi_next = NULL;
1144                 if (unlikely((bio->bi_rw & REQ_DISCARD) &&
1145                     !blk_queue_discard(bdev_get_queue(bio->bi_bdev))))
1146                         /* Just ignore it */
1147                         bio_endio(bio, 0);
1148                 else
1149                         generic_make_request(bio);
1150                 bio = next;
1151         }
1152         kfree(plug);
1153 }
1154
1155 static void make_request(struct mddev *mddev, struct bio * bio)
1156 {
1157         struct r10conf *conf = mddev->private;
1158         struct r10bio *r10_bio;
1159         struct bio *read_bio;
1160         int i;
1161         sector_t chunk_mask = (conf->geo.chunk_mask & conf->prev.chunk_mask);
1162         int chunk_sects = chunk_mask + 1;
1163         const int rw = bio_data_dir(bio);
1164         const unsigned long do_sync = (bio->bi_rw & REQ_SYNC);
1165         const unsigned long do_fua = (bio->bi_rw & REQ_FUA);
1166         const unsigned long do_discard = (bio->bi_rw
1167                                           & (REQ_DISCARD | REQ_SECURE));
1168         const unsigned long do_same = (bio->bi_rw & REQ_WRITE_SAME);
1169         unsigned long flags;
1170         struct md_rdev *blocked_rdev;
1171         struct blk_plug_cb *cb;
1172         struct raid10_plug_cb *plug = NULL;
1173         int sectors_handled;
1174         int max_sectors;
1175         int sectors;
1176
1177         if (unlikely(bio->bi_rw & REQ_FLUSH)) {
1178                 md_flush_request(mddev, bio);
1179                 return;
1180         }
1181
1182         /* If this request crosses a chunk boundary, we need to
1183          * split it.  This will only happen for 1 PAGE (or less) requests.
1184          */
1185         if (unlikely((bio->bi_sector & chunk_mask) + bio_sectors(bio)
1186                      > chunk_sects
1187                      && (conf->geo.near_copies < conf->geo.raid_disks
1188                          || conf->prev.near_copies < conf->prev.raid_disks))) {
1189                 struct bio_pair *bp;
1190                 /* Sanity check -- queue functions should prevent this happening */
1191                 if (bio_segments(bio) > 1)
1192                         goto bad_map;
1193                 /* This is a one page bio that upper layers
1194                  * refuse to split for us, so we need to split it.
1195                  */
1196                 bp = bio_split(bio,
1197                                chunk_sects - (bio->bi_sector & (chunk_sects - 1)) );
1198
1199                 /* Each of these 'make_request' calls will call 'wait_barrier'.
1200                  * If the first succeeds but the second blocks due to the resync
1201                  * thread raising the barrier, we will deadlock because the
1202                  * IO to the underlying device will be queued in generic_make_request
1203                  * and will never complete, so will never reduce nr_pending.
1204                  * So increment nr_waiting here so no new raise_barriers will
1205                  * succeed, and so the second wait_barrier cannot block.
1206                  */
1207                 spin_lock_irq(&conf->resync_lock);
1208                 conf->nr_waiting++;
1209                 spin_unlock_irq(&conf->resync_lock);
1210
1211                 make_request(mddev, &bp->bio1);
1212                 make_request(mddev, &bp->bio2);
1213
1214                 spin_lock_irq(&conf->resync_lock);
1215                 conf->nr_waiting--;
1216                 wake_up(&conf->wait_barrier);
1217                 spin_unlock_irq(&conf->resync_lock);
1218
1219                 bio_pair_release(bp);
1220                 return;
1221         bad_map:
1222                 printk("md/raid10:%s: make_request bug: can't convert block across chunks"
1223                        " or bigger than %dk %llu %d\n", mdname(mddev), chunk_sects/2,
1224                        (unsigned long long)bio->bi_sector, bio_sectors(bio) / 2);
1225
1226                 bio_io_error(bio);
1227                 return;
1228         }
1229
1230         md_write_start(mddev, bio);
1231
1232         /*
1233          * Register the new request and wait if the reconstruction
1234          * thread has put up a bar for new requests.
1235          * Continue immediately if no resync is active currently.
1236          */
1237         wait_barrier(conf);
1238
1239         sectors = bio_sectors(bio);
1240         while (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
1241             bio->bi_sector < conf->reshape_progress &&
1242             bio->bi_sector + sectors > conf->reshape_progress) {
1243                 /* IO spans the reshape position.  Need to wait for
1244                  * reshape to pass
1245                  */
1246                 allow_barrier(conf);
1247                 wait_event(conf->wait_barrier,
1248                            conf->reshape_progress <= bio->bi_sector ||
1249                            conf->reshape_progress >= bio->bi_sector + sectors);
1250                 wait_barrier(conf);
1251         }
1252         if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
1253             bio_data_dir(bio) == WRITE &&
1254             (mddev->reshape_backwards
1255              ? (bio->bi_sector < conf->reshape_safe &&
1256                 bio->bi_sector + sectors > conf->reshape_progress)
1257              : (bio->bi_sector + sectors > conf->reshape_safe &&
1258                 bio->bi_sector < conf->reshape_progress))) {
1259                 /* Need to update reshape_position in metadata */
1260                 mddev->reshape_position = conf->reshape_progress;
1261                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
1262                 set_bit(MD_CHANGE_PENDING, &mddev->flags);
1263                 md_wakeup_thread(mddev->thread);
1264                 wait_event(mddev->sb_wait,
1265                            !test_bit(MD_CHANGE_PENDING, &mddev->flags));
1266
1267                 conf->reshape_safe = mddev->reshape_position;
1268         }
1269
1270         r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
1271
1272         r10_bio->master_bio = bio;
1273         r10_bio->sectors = sectors;
1274
1275         r10_bio->mddev = mddev;
1276         r10_bio->sector = bio->bi_sector;
1277         r10_bio->state = 0;
1278
1279         /* We might need to issue multiple reads to different
1280          * devices if there are bad blocks around, so we keep
1281          * track of the number of reads in bio->bi_phys_segments.
1282          * If this is 0, there is only one r10_bio and no locking
1283          * will be needed when the request completes.  If it is
1284          * non-zero, then it is the number of not-completed requests.
1285          */
1286         bio->bi_phys_segments = 0;
1287         clear_bit(BIO_SEG_VALID, &bio->bi_flags);
1288
1289         if (rw == READ) {
1290                 /*
1291                  * read balancing logic:
1292                  */
1293                 struct md_rdev *rdev;
1294                 int slot;
1295
1296 read_again:
1297                 rdev = read_balance(conf, r10_bio, &max_sectors);
1298                 if (!rdev) {
1299                         raid_end_bio_io(r10_bio);
1300                         return;
1301                 }
1302                 slot = r10_bio->read_slot;
1303
1304                 read_bio = bio_clone_mddev(bio, GFP_NOIO, mddev);
1305                 md_trim_bio(read_bio, r10_bio->sector - bio->bi_sector,
1306                             max_sectors);
1307
1308                 r10_bio->devs[slot].bio = read_bio;
1309                 r10_bio->devs[slot].rdev = rdev;
1310
1311                 read_bio->bi_sector = r10_bio->devs[slot].addr +
1312                         choose_data_offset(r10_bio, rdev);
1313                 read_bio->bi_bdev = rdev->bdev;
1314                 read_bio->bi_end_io = raid10_end_read_request;
1315                 read_bio->bi_rw = READ | do_sync;
1316                 read_bio->bi_private = r10_bio;
1317
1318                 if (max_sectors < r10_bio->sectors) {
1319                         /* Could not read all from this device, so we will
1320                          * need another r10_bio.
1321                          */
1322                         sectors_handled = (r10_bio->sectors + max_sectors
1323                                            - bio->bi_sector);
1324                         r10_bio->sectors = max_sectors;
1325                         spin_lock_irq(&conf->device_lock);
1326                         if (bio->bi_phys_segments == 0)
1327                                 bio->bi_phys_segments = 2;
1328                         else
1329                                 bio->bi_phys_segments++;
1330                         spin_unlock(&conf->device_lock);
1331                         /* Cannot call generic_make_request directly
1332                          * as that will be queued in __generic_make_request
1333                          * and subsequent mempool_alloc might block
1334                          * waiting for it.  so hand bio over to raid10d.
1335                          */
1336                         reschedule_retry(r10_bio);
1337
1338                         r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
1339
1340                         r10_bio->master_bio = bio;
1341                         r10_bio->sectors = bio_sectors(bio) - sectors_handled;
1342                         r10_bio->state = 0;
1343                         r10_bio->mddev = mddev;
1344                         r10_bio->sector = bio->bi_sector + sectors_handled;
1345                         goto read_again;
1346                 } else
1347                         generic_make_request(read_bio);
1348                 return;
1349         }
1350
1351         /*
1352          * WRITE:
1353          */
1354         if (conf->pending_count >= max_queued_requests) {
1355                 md_wakeup_thread(mddev->thread);
1356                 wait_event(conf->wait_barrier,
1357                            conf->pending_count < max_queued_requests);
1358         }
1359         /* first select target devices under rcu_lock and
1360          * inc refcount on their rdev.  Record them by setting
1361          * bios[x] to bio
1362          * If there are known/acknowledged bad blocks on any device
1363          * on which we have seen a write error, we want to avoid
1364          * writing to those blocks.  This potentially requires several
1365          * writes to write around the bad blocks.  Each set of writes
1366          * gets its own r10_bio with a set of bios attached.  The number
1367          * of r10_bios is recored in bio->bi_phys_segments just as with
1368          * the read case.
1369          */
1370
1371         r10_bio->read_slot = -1; /* make sure repl_bio gets freed */
1372         raid10_find_phys(conf, r10_bio);
1373 retry_write:
1374         blocked_rdev = NULL;
1375         rcu_read_lock();
1376         max_sectors = r10_bio->sectors;
1377
1378         for (i = 0;  i < conf->copies; i++) {
1379                 int d = r10_bio->devs[i].devnum;
1380                 struct md_rdev *rdev = rcu_dereference(conf->mirrors[d].rdev);
1381                 struct md_rdev *rrdev = rcu_dereference(
1382                         conf->mirrors[d].replacement);
1383                 if (rdev == rrdev)
1384                         rrdev = NULL;
1385                 if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
1386                         atomic_inc(&rdev->nr_pending);
1387                         blocked_rdev = rdev;
1388                         break;
1389                 }
1390                 if (rrdev && unlikely(test_bit(Blocked, &rrdev->flags))) {
1391                         atomic_inc(&rrdev->nr_pending);
1392                         blocked_rdev = rrdev;
1393                         break;
1394                 }
1395                 if (rdev && (test_bit(Faulty, &rdev->flags)
1396                              || test_bit(Unmerged, &rdev->flags)))
1397                         rdev = NULL;
1398                 if (rrdev && (test_bit(Faulty, &rrdev->flags)
1399                               || test_bit(Unmerged, &rrdev->flags)))
1400                         rrdev = NULL;
1401
1402                 r10_bio->devs[i].bio = NULL;
1403                 r10_bio->devs[i].repl_bio = NULL;
1404
1405                 if (!rdev && !rrdev) {
1406                         set_bit(R10BIO_Degraded, &r10_bio->state);
1407                         continue;
1408                 }
1409                 if (rdev && test_bit(WriteErrorSeen, &rdev->flags)) {
1410                         sector_t first_bad;
1411                         sector_t dev_sector = r10_bio->devs[i].addr;
1412                         int bad_sectors;
1413                         int is_bad;
1414
1415                         is_bad = is_badblock(rdev, dev_sector,
1416                                              max_sectors,
1417                                              &first_bad, &bad_sectors);
1418                         if (is_bad < 0) {
1419                                 /* Mustn't write here until the bad block
1420                                  * is acknowledged
1421                                  */
1422                                 atomic_inc(&rdev->nr_pending);
1423                                 set_bit(BlockedBadBlocks, &rdev->flags);
1424                                 blocked_rdev = rdev;
1425                                 break;
1426                         }
1427                         if (is_bad && first_bad <= dev_sector) {
1428                                 /* Cannot write here at all */
1429                                 bad_sectors -= (dev_sector - first_bad);
1430                                 if (bad_sectors < max_sectors)
1431                                         /* Mustn't write more than bad_sectors
1432                                          * to other devices yet
1433                                          */
1434                                         max_sectors = bad_sectors;
1435                                 /* We don't set R10BIO_Degraded as that
1436                                  * only applies if the disk is missing,
1437                                  * so it might be re-added, and we want to
1438                                  * know to recover this chunk.
1439                                  * In this case the device is here, and the
1440                                  * fact that this chunk is not in-sync is
1441                                  * recorded in the bad block log.
1442                                  */
1443                                 continue;
1444                         }
1445                         if (is_bad) {
1446                                 int good_sectors = first_bad - dev_sector;
1447                                 if (good_sectors < max_sectors)
1448                                         max_sectors = good_sectors;
1449                         }
1450                 }
1451                 if (rdev) {
1452                         r10_bio->devs[i].bio = bio;
1453                         atomic_inc(&rdev->nr_pending);
1454                 }
1455                 if (rrdev) {
1456                         r10_bio->devs[i].repl_bio = bio;
1457                         atomic_inc(&rrdev->nr_pending);
1458                 }
1459         }
1460         rcu_read_unlock();
1461
1462         if (unlikely(blocked_rdev)) {
1463                 /* Have to wait for this device to get unblocked, then retry */
1464                 int j;
1465                 int d;
1466
1467                 for (j = 0; j < i; j++) {
1468                         if (r10_bio->devs[j].bio) {
1469                                 d = r10_bio->devs[j].devnum;
1470                                 rdev_dec_pending(conf->mirrors[d].rdev, mddev);
1471                         }
1472                         if (r10_bio->devs[j].repl_bio) {
1473                                 struct md_rdev *rdev;
1474                                 d = r10_bio->devs[j].devnum;
1475                                 rdev = conf->mirrors[d].replacement;
1476                                 if (!rdev) {
1477                                         /* Race with remove_disk */
1478                                         smp_mb();
1479                                         rdev = conf->mirrors[d].rdev;
1480                                 }
1481                                 rdev_dec_pending(rdev, mddev);
1482                         }
1483                 }
1484                 allow_barrier(conf);
1485                 md_wait_for_blocked_rdev(blocked_rdev, mddev);
1486                 wait_barrier(conf);
1487                 goto retry_write;
1488         }
1489
1490         if (max_sectors < r10_bio->sectors) {
1491                 /* We are splitting this into multiple parts, so
1492                  * we need to prepare for allocating another r10_bio.
1493                  */
1494                 r10_bio->sectors = max_sectors;
1495                 spin_lock_irq(&conf->device_lock);
1496                 if (bio->bi_phys_segments == 0)
1497                         bio->bi_phys_segments = 2;
1498                 else
1499                         bio->bi_phys_segments++;
1500                 spin_unlock_irq(&conf->device_lock);
1501         }
1502         sectors_handled = r10_bio->sector + max_sectors - bio->bi_sector;
1503
1504         atomic_set(&r10_bio->remaining, 1);
1505         bitmap_startwrite(mddev->bitmap, r10_bio->sector, r10_bio->sectors, 0);
1506
1507         for (i = 0; i < conf->copies; i++) {
1508                 struct bio *mbio;
1509                 int d = r10_bio->devs[i].devnum;
1510                 if (r10_bio->devs[i].bio) {
1511                         struct md_rdev *rdev = conf->mirrors[d].rdev;
1512                         mbio = bio_clone_mddev(bio, GFP_NOIO, mddev);
1513                         md_trim_bio(mbio, r10_bio->sector - bio->bi_sector,
1514                                     max_sectors);
1515                         r10_bio->devs[i].bio = mbio;
1516
1517                         mbio->bi_sector = (r10_bio->devs[i].addr+
1518                                            choose_data_offset(r10_bio,
1519                                                               rdev));
1520                         mbio->bi_bdev = rdev->bdev;
1521                         mbio->bi_end_io = raid10_end_write_request;
1522                         mbio->bi_rw =
1523                                 WRITE | do_sync | do_fua | do_discard | do_same;
1524                         mbio->bi_private = r10_bio;
1525
1526                         atomic_inc(&r10_bio->remaining);
1527
1528                         cb = blk_check_plugged(raid10_unplug, mddev,
1529                                                sizeof(*plug));
1530                         if (cb)
1531                                 plug = container_of(cb, struct raid10_plug_cb,
1532                                                     cb);
1533                         else
1534                                 plug = NULL;
1535                         spin_lock_irqsave(&conf->device_lock, flags);
1536                         if (plug) {
1537                                 bio_list_add(&plug->pending, mbio);
1538                                 plug->pending_cnt++;
1539                         } else {
1540                                 bio_list_add(&conf->pending_bio_list, mbio);
1541                                 conf->pending_count++;
1542                         }
1543                         spin_unlock_irqrestore(&conf->device_lock, flags);
1544                         if (!plug)
1545                                 md_wakeup_thread(mddev->thread);
1546                 }
1547
1548                 if (r10_bio->devs[i].repl_bio) {
1549                         struct md_rdev *rdev = conf->mirrors[d].replacement;
1550                         if (rdev == NULL) {
1551                                 /* Replacement just got moved to main 'rdev' */
1552                                 smp_mb();
1553                                 rdev = conf->mirrors[d].rdev;
1554                         }
1555                         mbio = bio_clone_mddev(bio, GFP_NOIO, mddev);
1556                         md_trim_bio(mbio, r10_bio->sector - bio->bi_sector,
1557                                     max_sectors);
1558                         r10_bio->devs[i].repl_bio = mbio;
1559
1560                         mbio->bi_sector = (r10_bio->devs[i].addr +
1561                                            choose_data_offset(
1562                                                    r10_bio, rdev));
1563                         mbio->bi_bdev = rdev->bdev;
1564                         mbio->bi_end_io = raid10_end_write_request;
1565                         mbio->bi_rw =
1566                                 WRITE | do_sync | do_fua | do_discard | do_same;
1567                         mbio->bi_private = r10_bio;
1568
1569                         atomic_inc(&r10_bio->remaining);
1570                         spin_lock_irqsave(&conf->device_lock, flags);
1571                         bio_list_add(&conf->pending_bio_list, mbio);
1572                         conf->pending_count++;
1573                         spin_unlock_irqrestore(&conf->device_lock, flags);
1574                         if (!mddev_check_plugged(mddev))
1575                                 md_wakeup_thread(mddev->thread);
1576                 }
1577         }
1578
1579         /* Don't remove the bias on 'remaining' (one_write_done) until
1580          * after checking if we need to go around again.
1581          */
1582
1583         if (sectors_handled < bio_sectors(bio)) {
1584                 one_write_done(r10_bio);
1585                 /* We need another r10_bio.  It has already been counted
1586                  * in bio->bi_phys_segments.
1587                  */
1588                 r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
1589
1590                 r10_bio->master_bio = bio;
1591                 r10_bio->sectors = bio_sectors(bio) - sectors_handled;
1592
1593                 r10_bio->mddev = mddev;
1594                 r10_bio->sector = bio->bi_sector + sectors_handled;
1595                 r10_bio->state = 0;
1596                 goto retry_write;
1597         }
1598         one_write_done(r10_bio);
1599
1600         /* In case raid10d snuck in to freeze_array */
1601         wake_up(&conf->wait_barrier);
1602 }
1603
1604 static void status(struct seq_file *seq, struct mddev *mddev)
1605 {
1606         struct r10conf *conf = mddev->private;
1607         int i;
1608
1609         if (conf->geo.near_copies < conf->geo.raid_disks)
1610                 seq_printf(seq, " %dK chunks", mddev->chunk_sectors / 2);
1611         if (conf->geo.near_copies > 1)
1612                 seq_printf(seq, " %d near-copies", conf->geo.near_copies);
1613         if (conf->geo.far_copies > 1) {
1614                 if (conf->geo.far_offset)
1615                         seq_printf(seq, " %d offset-copies", conf->geo.far_copies);
1616                 else
1617                         seq_printf(seq, " %d far-copies", conf->geo.far_copies);
1618         }
1619         seq_printf(seq, " [%d/%d] [", conf->geo.raid_disks,
1620                                         conf->geo.raid_disks - mddev->degraded);
1621         for (i = 0; i < conf->geo.raid_disks; i++)
1622                 seq_printf(seq, "%s",
1623                               conf->mirrors[i].rdev &&
1624                               test_bit(In_sync, &conf->mirrors[i].rdev->flags) ? "U" : "_");
1625         seq_printf(seq, "]");
1626 }
1627
1628 /* check if there are enough drives for
1629  * every block to appear on atleast one.
1630  * Don't consider the device numbered 'ignore'
1631  * as we might be about to remove it.
1632  */
1633 static int _enough(struct r10conf *conf, int previous, int ignore)
1634 {
1635         int first = 0;
1636         int disks, ncopies;
1637         if (previous) {
1638                 disks = conf->prev.raid_disks;
1639                 ncopies = conf->prev.near_copies;
1640         } else {
1641                 disks = conf->geo.raid_disks;
1642                 ncopies = conf->geo.near_copies;
1643         }
1644
1645         do {
1646                 int n = conf->copies;
1647                 int cnt = 0;
1648                 int this = first;
1649                 while (n--) {
1650                         if (conf->mirrors[this].rdev &&
1651                             this != ignore)
1652                                 cnt++;
1653                         this = (this+1) % disks;
1654                 }
1655                 if (cnt == 0)
1656                         return 0;
1657                 first = (first + ncopies) % disks;
1658         } while (first != 0);
1659         return 1;
1660 }
1661
1662 static int enough(struct r10conf *conf, int ignore)
1663 {
1664         /* when calling 'enough', both 'prev' and 'geo' must
1665          * be stable.
1666          * This is ensured if ->reconfig_mutex or ->device_lock
1667          * is held.
1668          */
1669         return _enough(conf, 0, ignore) &&
1670                 _enough(conf, 1, ignore);
1671 }
1672
1673 static void error(struct mddev *mddev, struct md_rdev *rdev)
1674 {
1675         char b[BDEVNAME_SIZE];
1676         struct r10conf *conf = mddev->private;
1677         unsigned long flags;
1678
1679         /*
1680          * If it is not operational, then we have already marked it as dead
1681          * else if it is the last working disks, ignore the error, let the
1682          * next level up know.
1683          * else mark the drive as failed
1684          */
1685         spin_lock_irqsave(&conf->device_lock, flags);
1686         if (test_bit(In_sync, &rdev->flags)
1687             && !enough(conf, rdev->raid_disk)) {
1688                 /*
1689                  * Don't fail the drive, just return an IO error.
1690                  */
1691                 spin_unlock_irqrestore(&conf->device_lock, flags);
1692                 return;
1693         }
1694         if (test_and_clear_bit(In_sync, &rdev->flags)) {
1695                 mddev->degraded++;
1696                         /*
1697                  * if recovery is running, make sure it aborts.
1698                  */
1699                 set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1700         }
1701         set_bit(Blocked, &rdev->flags);
1702         set_bit(Faulty, &rdev->flags);
1703         set_bit(MD_CHANGE_DEVS, &mddev->flags);
1704         spin_unlock_irqrestore(&conf->device_lock, flags);
1705         printk(KERN_ALERT
1706                "md/raid10:%s: Disk failure on %s, disabling device.\n"
1707                "md/raid10:%s: Operation continuing on %d devices.\n",
1708                mdname(mddev), bdevname(rdev->bdev, b),
1709                mdname(mddev), conf->geo.raid_disks - mddev->degraded);
1710 }
1711
1712 static void print_conf(struct r10conf *conf)
1713 {
1714         int i;
1715         struct raid10_info *tmp;
1716
1717         printk(KERN_DEBUG "RAID10 conf printout:\n");
1718         if (!conf) {
1719                 printk(KERN_DEBUG "(!conf)\n");
1720                 return;
1721         }
1722         printk(KERN_DEBUG " --- wd:%d rd:%d\n", conf->geo.raid_disks - conf->mddev->degraded,
1723                 conf->geo.raid_disks);
1724
1725         for (i = 0; i < conf->geo.raid_disks; i++) {
1726                 char b[BDEVNAME_SIZE];
1727                 tmp = conf->mirrors + i;
1728                 if (tmp->rdev)
1729                         printk(KERN_DEBUG " disk %d, wo:%d, o:%d, dev:%s\n",
1730                                 i, !test_bit(In_sync, &tmp->rdev->flags),
1731                                 !test_bit(Faulty, &tmp->rdev->flags),
1732                                 bdevname(tmp->rdev->bdev,b));
1733         }
1734 }
1735
1736 static void close_sync(struct r10conf *conf)
1737 {
1738         wait_barrier(conf);
1739         allow_barrier(conf);
1740
1741         mempool_destroy(conf->r10buf_pool);
1742         conf->r10buf_pool = NULL;
1743 }
1744
1745 static int raid10_spare_active(struct mddev *mddev)
1746 {
1747         int i;
1748         struct r10conf *conf = mddev->private;
1749         struct raid10_info *tmp;
1750         int count = 0;
1751         unsigned long flags;
1752
1753         /*
1754          * Find all non-in_sync disks within the RAID10 configuration
1755          * and mark them in_sync
1756          */
1757         for (i = 0; i < conf->geo.raid_disks; i++) {
1758                 tmp = conf->mirrors + i;
1759                 if (tmp->replacement
1760                     && tmp->replacement->recovery_offset == MaxSector
1761                     && !test_bit(Faulty, &tmp->replacement->flags)
1762                     && !test_and_set_bit(In_sync, &tmp->replacement->flags)) {
1763                         /* Replacement has just become active */
1764                         if (!tmp->rdev
1765                             || !test_and_clear_bit(In_sync, &tmp->rdev->flags))
1766                                 count++;
1767                         if (tmp->rdev) {
1768                                 /* Replaced device not technically faulty,
1769                                  * but we need to be sure it gets removed
1770                                  * and never re-added.
1771                                  */
1772                                 set_bit(Faulty, &tmp->rdev->flags);
1773                                 sysfs_notify_dirent_safe(
1774                                         tmp->rdev->sysfs_state);
1775                         }
1776                         sysfs_notify_dirent_safe(tmp->replacement->sysfs_state);
1777                 } else if (tmp->rdev
1778                            && !test_bit(Faulty, &tmp->rdev->flags)
1779                            && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
1780                         count++;
1781                         sysfs_notify_dirent_safe(tmp->rdev->sysfs_state);
1782                 }
1783         }
1784         spin_lock_irqsave(&conf->device_lock, flags);
1785         mddev->degraded -= count;
1786         spin_unlock_irqrestore(&conf->device_lock, flags);
1787
1788         print_conf(conf);
1789         return count;
1790 }
1791
1792
1793 static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev)
1794 {
1795         struct r10conf *conf = mddev->private;
1796         int err = -EEXIST;
1797         int mirror;
1798         int first = 0;
1799         int last = conf->geo.raid_disks - 1;
1800         struct request_queue *q = bdev_get_queue(rdev->bdev);
1801
1802         if (mddev->recovery_cp < MaxSector)
1803                 /* only hot-add to in-sync arrays, as recovery is
1804                  * very different from resync
1805                  */
1806                 return -EBUSY;
1807         if (rdev->saved_raid_disk < 0 && !_enough(conf, 1, -1))
1808                 return -EINVAL;
1809
1810         if (rdev->raid_disk >= 0)
1811                 first = last = rdev->raid_disk;
1812
1813         if (q->merge_bvec_fn) {
1814                 set_bit(Unmerged, &rdev->flags);
1815                 mddev->merge_check_needed = 1;
1816         }
1817
1818         if (rdev->saved_raid_disk >= first &&
1819             conf->mirrors[rdev->saved_raid_disk].rdev == NULL)
1820                 mirror = rdev->saved_raid_disk;
1821         else
1822                 mirror = first;
1823         for ( ; mirror <= last ; mirror++) {
1824                 struct raid10_info *p = &conf->mirrors[mirror];
1825                 if (p->recovery_disabled == mddev->recovery_disabled)
1826                         continue;
1827                 if (p->rdev) {
1828                         if (!test_bit(WantReplacement, &p->rdev->flags) ||
1829                             p->replacement != NULL)
1830                                 continue;
1831                         clear_bit(In_sync, &rdev->flags);
1832                         set_bit(Replacement, &rdev->flags);
1833                         rdev->raid_disk = mirror;
1834                         err = 0;
1835                         if (mddev->gendisk)
1836                                 disk_stack_limits(mddev->gendisk, rdev->bdev,
1837                                                   rdev->data_offset << 9);
1838                         conf->fullsync = 1;
1839                         rcu_assign_pointer(p->replacement, rdev);
1840                         break;
1841                 }
1842
1843                 if (mddev->gendisk)
1844                         disk_stack_limits(mddev->gendisk, rdev->bdev,
1845                                           rdev->data_offset << 9);
1846
1847                 p->head_position = 0;
1848                 p->recovery_disabled = mddev->recovery_disabled - 1;
1849                 rdev->raid_disk = mirror;
1850                 err = 0;
1851                 if (rdev->saved_raid_disk != mirror)
1852                         conf->fullsync = 1;
1853                 rcu_assign_pointer(p->rdev, rdev);
1854                 break;
1855         }
1856         if (err == 0 && test_bit(Unmerged, &rdev->flags)) {
1857                 /* Some requests might not have seen this new
1858                  * merge_bvec_fn.  We must wait for them to complete
1859                  * before merging the device fully.
1860                  * First we make sure any code which has tested
1861                  * our function has submitted the request, then
1862                  * we wait for all outstanding requests to complete.
1863                  */
1864                 synchronize_sched();
1865                 freeze_array(conf, 0);
1866                 unfreeze_array(conf);
1867                 clear_bit(Unmerged, &rdev->flags);
1868         }
1869         md_integrity_add_rdev(rdev, mddev);
1870         if (mddev->queue && blk_queue_discard(bdev_get_queue(rdev->bdev)))
1871                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
1872
1873         print_conf(conf);
1874         return err;
1875 }
1876
1877 static int raid10_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
1878 {
1879         struct r10conf *conf = mddev->private;
1880         int err = 0;
1881         int number = rdev->raid_disk;
1882         struct md_rdev **rdevp;
1883         struct raid10_info *p = conf->mirrors + number;
1884
1885         print_conf(conf);
1886         if (rdev == p->rdev)
1887                 rdevp = &p->rdev;
1888         else if (rdev == p->replacement)
1889                 rdevp = &p->replacement;
1890         else
1891                 return 0;
1892
1893         if (test_bit(In_sync, &rdev->flags) ||
1894             atomic_read(&rdev->nr_pending)) {
1895                 err = -EBUSY;
1896                 goto abort;
1897         }
1898         /* Only remove faulty devices if recovery
1899          * is not possible.
1900          */
1901         if (!test_bit(Faulty, &rdev->flags) &&
1902             mddev->recovery_disabled != p->recovery_disabled &&
1903             (!p->replacement || p->replacement == rdev) &&
1904             number < conf->geo.raid_disks &&
1905             enough(conf, -1)) {
1906                 err = -EBUSY;
1907                 goto abort;
1908         }
1909         *rdevp = NULL;
1910         synchronize_rcu();
1911         if (atomic_read(&rdev->nr_pending)) {
1912                 /* lost the race, try later */
1913                 err = -EBUSY;
1914                 *rdevp = rdev;
1915                 goto abort;
1916         } else if (p->replacement) {
1917                 /* We must have just cleared 'rdev' */
1918                 p->rdev = p->replacement;
1919                 clear_bit(Replacement, &p->replacement->flags);
1920                 smp_mb(); /* Make sure other CPUs may see both as identical
1921                            * but will never see neither -- if they are careful.
1922                            */
1923                 p->replacement = NULL;
1924                 clear_bit(WantReplacement, &rdev->flags);
1925         } else
1926                 /* We might have just remove the Replacement as faulty
1927                  * Clear the flag just in case
1928                  */
1929                 clear_bit(WantReplacement, &rdev->flags);
1930
1931         err = md_integrity_register(mddev);
1932
1933 abort:
1934
1935         print_conf(conf);
1936         return err;
1937 }
1938
1939
1940 static void end_sync_read(struct bio *bio, int error)
1941 {
1942         struct r10bio *r10_bio = bio->bi_private;
1943         struct r10conf *conf = r10_bio->mddev->private;
1944         int d;
1945
1946         if (bio == r10_bio->master_bio) {
1947                 /* this is a reshape read */
1948                 d = r10_bio->read_slot; /* really the read dev */
1949         } else
1950                 d = find_bio_disk(conf, r10_bio, bio, NULL, NULL);
1951
1952         if (test_bit(BIO_UPTODATE, &bio->bi_flags))
1953                 set_bit(R10BIO_Uptodate, &r10_bio->state);
1954         else
1955                 /* The write handler will notice the lack of
1956                  * R10BIO_Uptodate and record any errors etc
1957                  */
1958                 atomic_add(r10_bio->sectors,
1959                            &conf->mirrors[d].rdev->corrected_errors);
1960
1961         /* for reconstruct, we always reschedule after a read.
1962          * for resync, only after all reads
1963          */
1964         rdev_dec_pending(conf->mirrors[d].rdev, conf->mddev);
1965         if (test_bit(R10BIO_IsRecover, &r10_bio->state) ||
1966             atomic_dec_and_test(&r10_bio->remaining)) {
1967                 /* we have read all the blocks,
1968                  * do the comparison in process context in raid10d
1969                  */
1970                 reschedule_retry(r10_bio);
1971         }
1972 }
1973
1974 static void end_sync_request(struct r10bio *r10_bio)
1975 {
1976         struct mddev *mddev = r10_bio->mddev;
1977
1978         while (atomic_dec_and_test(&r10_bio->remaining)) {
1979                 if (r10_bio->master_bio == NULL) {
1980                         /* the primary of several recovery bios */
1981                         sector_t s = r10_bio->sectors;
1982                         if (test_bit(R10BIO_MadeGood, &r10_bio->state) ||
1983                             test_bit(R10BIO_WriteError, &r10_bio->state))
1984                                 reschedule_retry(r10_bio);
1985                         else
1986                                 put_buf(r10_bio);
1987                         md_done_sync(mddev, s, 1);
1988                         break;
1989                 } else {
1990                         struct r10bio *r10_bio2 = (struct r10bio *)r10_bio->master_bio;
1991                         if (test_bit(R10BIO_MadeGood, &r10_bio->state) ||
1992                             test_bit(R10BIO_WriteError, &r10_bio->state))
1993                                 reschedule_retry(r10_bio);
1994                         else
1995                                 put_buf(r10_bio);
1996                         r10_bio = r10_bio2;
1997                 }
1998         }
1999 }
2000
2001 static void end_sync_write(struct bio *bio, int error)
2002 {
2003         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
2004         struct r10bio *r10_bio = bio->bi_private;
2005         struct mddev *mddev = r10_bio->mddev;
2006         struct r10conf *conf = mddev->private;
2007         int d;
2008         sector_t first_bad;
2009         int bad_sectors;
2010         int slot;
2011         int repl;
2012         struct md_rdev *rdev = NULL;
2013
2014         d = find_bio_disk(conf, r10_bio, bio, &slot, &repl);
2015         if (repl)
2016                 rdev = conf->mirrors[d].replacement;
2017         else
2018                 rdev = conf->mirrors[d].rdev;
2019
2020         if (!uptodate) {
2021                 if (repl)
2022                         md_error(mddev, rdev);
2023                 else {
2024                         set_bit(WriteErrorSeen, &rdev->flags);
2025                         if (!test_and_set_bit(WantReplacement, &rdev->flags))
2026                                 set_bit(MD_RECOVERY_NEEDED,
2027                                         &rdev->mddev->recovery);
2028                         set_bit(R10BIO_WriteError, &r10_bio->state);
2029                 }
2030         } else if (is_badblock(rdev,
2031                              r10_bio->devs[slot].addr,
2032                              r10_bio->sectors,
2033                              &first_bad, &bad_sectors))
2034                 set_bit(R10BIO_MadeGood, &r10_bio->state);
2035
2036         rdev_dec_pending(rdev, mddev);
2037
2038         end_sync_request(r10_bio);
2039 }
2040
2041 /*
2042  * Note: sync and recover and handled very differently for raid10
2043  * This code is for resync.
2044  * For resync, we read through virtual addresses and read all blocks.
2045  * If there is any error, we schedule a write.  The lowest numbered
2046  * drive is authoritative.
2047  * However requests come for physical address, so we need to map.
2048  * For every physical address there are raid_disks/copies virtual addresses,
2049  * which is always are least one, but is not necessarly an integer.
2050  * This means that a physical address can span multiple chunks, so we may
2051  * have to submit multiple io requests for a single sync request.
2052  */
2053 /*
2054  * We check if all blocks are in-sync and only write to blocks that
2055  * aren't in sync
2056  */
2057 static void sync_request_write(struct mddev *mddev, struct r10bio *r10_bio)
2058 {
2059         struct r10conf *conf = mddev->private;
2060         int i, first;
2061         struct bio *tbio, *fbio;
2062         int vcnt;
2063
2064         atomic_set(&r10_bio->remaining, 1);
2065
2066         /* find the first device with a block */
2067         for (i=0; i<conf->copies; i++)
2068                 if (test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags))
2069                         break;
2070
2071         if (i == conf->copies)
2072                 goto done;
2073
2074         first = i;
2075         fbio = r10_bio->devs[i].bio;
2076
2077         vcnt = (r10_bio->sectors + (PAGE_SIZE >> 9) - 1) >> (PAGE_SHIFT - 9);
2078         /* now find blocks with errors */
2079         for (i=0 ; i < conf->copies ; i++) {
2080                 int  j, d;
2081
2082                 tbio = r10_bio->devs[i].bio;
2083
2084                 if (tbio->bi_end_io != end_sync_read)
2085                         continue;
2086                 if (i == first)
2087                         continue;
2088                 if (test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags)) {
2089                         /* We know that the bi_io_vec layout is the same for
2090                          * both 'first' and 'i', so we just compare them.
2091                          * All vec entries are PAGE_SIZE;
2092                          */
2093                         for (j = 0; j < vcnt; j++)
2094                                 if (memcmp(page_address(fbio->bi_io_vec[j].bv_page),
2095                                            page_address(tbio->bi_io_vec[j].bv_page),
2096                                            fbio->bi_io_vec[j].bv_len))
2097                                         break;
2098                         if (j == vcnt)
2099                                 continue;
2100                         atomic64_add(r10_bio->sectors, &mddev->resync_mismatches);
2101                         if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
2102                                 /* Don't fix anything. */
2103                                 continue;
2104                 }
2105                 /* Ok, we need to write this bio, either to correct an
2106                  * inconsistency or to correct an unreadable block.
2107                  * First we need to fixup bv_offset, bv_len and
2108                  * bi_vecs, as the read request might have corrupted these
2109                  */
2110                 bio_reset(tbio);
2111
2112                 tbio->bi_vcnt = vcnt;
2113                 tbio->bi_size = r10_bio->sectors << 9;
2114                 tbio->bi_rw = WRITE;
2115                 tbio->bi_private = r10_bio;
2116                 tbio->bi_sector = r10_bio->devs[i].addr;
2117
2118                 for (j=0; j < vcnt ; j++) {
2119                         tbio->bi_io_vec[j].bv_offset = 0;
2120                         tbio->bi_io_vec[j].bv_len = PAGE_SIZE;
2121
2122                         memcpy(page_address(tbio->bi_io_vec[j].bv_page),
2123                                page_address(fbio->bi_io_vec[j].bv_page),
2124                                PAGE_SIZE);
2125                 }
2126                 tbio->bi_end_io = end_sync_write;
2127
2128                 d = r10_bio->devs[i].devnum;
2129                 atomic_inc(&conf->mirrors[d].rdev->nr_pending);
2130                 atomic_inc(&r10_bio->remaining);
2131                 md_sync_acct(conf->mirrors[d].rdev->bdev, bio_sectors(tbio));
2132
2133                 tbio->bi_sector += conf->mirrors[d].rdev->data_offset;
2134                 tbio->bi_bdev = conf->mirrors[d].rdev->bdev;
2135                 generic_make_request(tbio);
2136         }
2137
2138         /* Now write out to any replacement devices
2139          * that are active
2140          */
2141         for (i = 0; i < conf->copies; i++) {
2142                 int j, d;
2143
2144                 tbio = r10_bio->devs[i].repl_bio;
2145                 if (!tbio || !tbio->bi_end_io)
2146                         continue;
2147                 if (r10_bio->devs[i].bio->bi_end_io != end_sync_write
2148                     && r10_bio->devs[i].bio != fbio)
2149                         for (j = 0; j < vcnt; j++)
2150                                 memcpy(page_address(tbio->bi_io_vec[j].bv_page),
2151                                        page_address(fbio->bi_io_vec[j].bv_page),
2152                                        PAGE_SIZE);
2153                 d = r10_bio->devs[i].devnum;
2154                 atomic_inc(&r10_bio->remaining);
2155                 md_sync_acct(conf->mirrors[d].replacement->bdev,
2156                              bio_sectors(tbio));
2157                 generic_make_request(tbio);
2158         }
2159
2160 done:
2161         if (atomic_dec_and_test(&r10_bio->remaining)) {
2162                 md_done_sync(mddev, r10_bio->sectors, 1);
2163                 put_buf(r10_bio);
2164         }
2165 }
2166
2167 /*
2168  * Now for the recovery code.
2169  * Recovery happens across physical sectors.
2170  * We recover all non-is_sync drives by finding the virtual address of
2171  * each, and then choose a working drive that also has that virt address.
2172  * There is a separate r10_bio for each non-in_sync drive.
2173  * Only the first two slots are in use. The first for reading,
2174  * The second for writing.
2175  *
2176  */
2177 static void fix_recovery_read_error(struct r10bio *r10_bio)
2178 {
2179         /* We got a read error during recovery.
2180          * We repeat the read in smaller page-sized sections.
2181          * If a read succeeds, write it to the new device or record
2182          * a bad block if we cannot.
2183          * If a read fails, record a bad block on both old and
2184          * new devices.
2185          */
2186         struct mddev *mddev = r10_bio->mddev;
2187         struct r10conf *conf = mddev->private;
2188         struct bio *bio = r10_bio->devs[0].bio;
2189         sector_t sect = 0;
2190         int sectors = r10_bio->sectors;
2191         int idx = 0;
2192         int dr = r10_bio->devs[0].devnum;
2193         int dw = r10_bio->devs[1].devnum;
2194
2195         while (sectors) {
2196                 int s = sectors;
2197                 struct md_rdev *rdev;
2198                 sector_t addr;
2199                 int ok;
2200
2201                 if (s > (PAGE_SIZE>>9))
2202                         s = PAGE_SIZE >> 9;
2203
2204                 rdev = conf->mirrors[dr].rdev;
2205                 addr = r10_bio->devs[0].addr + sect,
2206                 ok = sync_page_io(rdev,
2207                                   addr,
2208                                   s << 9,
2209                                   bio->bi_io_vec[idx].bv_page,
2210                                   READ, false);
2211                 if (ok) {
2212                         rdev = conf->mirrors[dw].rdev;
2213                         addr = r10_bio->devs[1].addr + sect;
2214                         ok = sync_page_io(rdev,
2215                                           addr,
2216                                           s << 9,
2217                                           bio->bi_io_vec[idx].bv_page,
2218                                           WRITE, false);
2219                         if (!ok) {
2220                                 set_bit(WriteErrorSeen, &rdev->flags);
2221                                 if (!test_and_set_bit(WantReplacement,
2222                                                       &rdev->flags))
2223                                         set_bit(MD_RECOVERY_NEEDED,
2224                                                 &rdev->mddev->recovery);
2225                         }
2226                 }
2227                 if (!ok) {
2228                         /* We don't worry if we cannot set a bad block -
2229                          * it really is bad so there is no loss in not
2230                          * recording it yet
2231                          */
2232                         rdev_set_badblocks(rdev, addr, s, 0);
2233
2234                         if (rdev != conf->mirrors[dw].rdev) {
2235                                 /* need bad block on destination too */
2236                                 struct md_rdev *rdev2 = conf->mirrors[dw].rdev;
2237                                 addr = r10_bio->devs[1].addr + sect;
2238                                 ok = rdev_set_badblocks(rdev2, addr, s, 0);
2239                                 if (!ok) {
2240                                         /* just abort the recovery */
2241                                         printk(KERN_NOTICE
2242                                                "md/raid10:%s: recovery aborted"
2243                                                " due to read error\n",
2244                                                mdname(mddev));
2245
2246                                         conf->mirrors[dw].recovery_disabled
2247                                                 = mddev->recovery_disabled;
2248                                         set_bit(MD_RECOVERY_INTR,
2249                                                 &mddev->recovery);
2250                                         break;
2251                                 }
2252                         }
2253                 }
2254
2255                 sectors -= s;
2256                 sect += s;
2257                 idx++;
2258         }
2259 }
2260
2261 static void recovery_request_write(struct mddev *mddev, struct r10bio *r10_bio)
2262 {
2263         struct r10conf *conf = mddev->private;
2264         int d;
2265         struct bio *wbio, *wbio2;
2266
2267         if (!test_bit(R10BIO_Uptodate, &r10_bio->state)) {
2268                 fix_recovery_read_error(r10_bio);
2269                 end_sync_request(r10_bio);
2270                 return;
2271         }
2272
2273         /*
2274          * share the pages with the first bio
2275          * and submit the write request
2276          */
2277         d = r10_bio->devs[1].devnum;
2278         wbio = r10_bio->devs[1].bio;
2279         wbio2 = r10_bio->devs[1].repl_bio;
2280         if (wbio->bi_end_io) {
2281                 atomic_inc(&conf->mirrors[d].rdev->nr_pending);
2282                 md_sync_acct(conf->mirrors[d].rdev->bdev, bio_sectors(wbio));
2283                 generic_make_request(wbio);
2284         }
2285         if (wbio2 && wbio2->bi_end_io) {
2286                 atomic_inc(&conf->mirrors[d].replacement->nr_pending);
2287                 md_sync_acct(conf->mirrors[d].replacement->bdev,
2288                              bio_sectors(wbio2));
2289                 generic_make_request(wbio2);
2290         }
2291 }
2292
2293
2294 /*
2295  * Used by fix_read_error() to decay the per rdev read_errors.
2296  * We halve the read error count for every hour that has elapsed
2297  * since the last recorded read error.
2298  *
2299  */
2300 static void check_decay_read_errors(struct mddev *mddev, struct md_rdev *rdev)
2301 {
2302         struct timespec cur_time_mon;
2303         unsigned long hours_since_last;
2304         unsigned int read_errors = atomic_read(&rdev->read_errors);
2305
2306         ktime_get_ts(&cur_time_mon);
2307
2308         if (rdev->last_read_error.tv_sec == 0 &&
2309             rdev->last_read_error.tv_nsec == 0) {
2310                 /* first time we've seen a read error */
2311                 rdev->last_read_error = cur_time_mon;
2312                 return;
2313         }
2314
2315         hours_since_last = (cur_time_mon.tv_sec -
2316                             rdev->last_read_error.tv_sec) / 3600;
2317
2318         rdev->last_read_error = cur_time_mon;
2319
2320         /*
2321          * if hours_since_last is > the number of bits in read_errors
2322          * just set read errors to 0. We do this to avoid
2323          * overflowing the shift of read_errors by hours_since_last.
2324          */
2325         if (hours_since_last >= 8 * sizeof(read_errors))
2326                 atomic_set(&rdev->read_errors, 0);
2327         else
2328                 atomic_set(&rdev->read_errors, read_errors >> hours_since_last);
2329 }
2330
2331 static int r10_sync_page_io(struct md_rdev *rdev, sector_t sector,
2332                             int sectors, struct page *page, int rw)
2333 {
2334         sector_t first_bad;
2335         int bad_sectors;
2336
2337         if (is_badblock(rdev, sector, sectors, &first_bad, &bad_sectors)
2338             && (rw == READ || test_bit(WriteErrorSeen, &rdev->flags)))
2339                 return -1;
2340         if (sync_page_io(rdev, sector, sectors << 9, page, rw, false))
2341                 /* success */
2342                 return 1;
2343         if (rw == WRITE) {
2344                 set_bit(WriteErrorSeen, &rdev->flags);
2345                 if (!test_and_set_bit(WantReplacement, &rdev->flags))
2346                         set_bit(MD_RECOVERY_NEEDED,
2347                                 &rdev->mddev->recovery);
2348         }
2349         /* need to record an error - either for the block or the device */
2350         if (!rdev_set_badblocks(rdev, sector, sectors, 0))
2351                 md_error(rdev->mddev, rdev);
2352         return 0;
2353 }
2354
2355 /*
2356  * This is a kernel thread which:
2357  *
2358  *      1.      Retries failed read operations on working mirrors.
2359  *      2.      Updates the raid superblock when problems encounter.
2360  *      3.      Performs writes following reads for array synchronising.
2361  */
2362
2363 static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10bio *r10_bio)
2364 {
2365         int sect = 0; /* Offset from r10_bio->sector */
2366         int sectors = r10_bio->sectors;
2367         struct md_rdev*rdev;
2368         int max_read_errors = atomic_read(&mddev->max_corr_read_errors);
2369         int d = r10_bio->devs[r10_bio->read_slot].devnum;
2370
2371         /* still own a reference to this rdev, so it cannot
2372          * have been cleared recently.
2373          */
2374         rdev = conf->mirrors[d].rdev;
2375
2376         if (test_bit(Faulty, &rdev->flags))
2377                 /* drive has already been failed, just ignore any
2378                    more fix_read_error() attempts */
2379                 return;
2380
2381         check_decay_read_errors(mddev, rdev);
2382         atomic_inc(&rdev->read_errors);
2383         if (atomic_read(&rdev->read_errors) > max_read_errors) {
2384                 char b[BDEVNAME_SIZE];
2385                 bdevname(rdev->bdev, b);
2386
2387                 printk(KERN_NOTICE
2388                        "md/raid10:%s: %s: Raid device exceeded "
2389                        "read_error threshold [cur %d:max %d]\n",
2390                        mdname(mddev), b,
2391                        atomic_read(&rdev->read_errors), max_read_errors);
2392                 printk(KERN_NOTICE
2393                        "md/raid10:%s: %s: Failing raid device\n",
2394                        mdname(mddev), b);
2395                 md_error(mddev, conf->mirrors[d].rdev);
2396                 r10_bio->devs[r10_bio->read_slot].bio = IO_BLOCKED;
2397                 return;
2398         }
2399
2400         while(sectors) {
2401                 int s = sectors;
2402                 int sl = r10_bio->read_slot;
2403                 int success = 0;
2404                 int start;
2405
2406                 if (s > (PAGE_SIZE>>9))
2407                         s = PAGE_SIZE >> 9;
2408
2409                 rcu_read_lock();
2410                 do {
2411                         sector_t first_bad;
2412                         int bad_sectors;
2413
2414                         d = r10_bio->devs[sl].devnum;
2415                         rdev = rcu_dereference(conf->mirrors[d].rdev);
2416                         if (rdev &&
2417                             !test_bit(Unmerged, &rdev->flags) &&
2418                             test_bit(In_sync, &rdev->flags) &&
2419                             is_badblock(rdev, r10_bio->devs[sl].addr + sect, s,
2420                                         &first_bad, &bad_sectors) == 0) {
2421                                 atomic_inc(&rdev->nr_pending);
2422                                 rcu_read_unlock();
2423                                 success = sync_page_io(rdev,
2424                                                        r10_bio->devs[sl].addr +
2425                                                        sect,
2426                                                        s<<9,
2427                                                        conf->tmppage, READ, false);
2428                                 rdev_dec_pending(rdev, mddev);
2429                                 rcu_read_lock();
2430                                 if (success)
2431                                         break;
2432                         }
2433                         sl++;
2434                         if (sl == conf->copies)
2435                                 sl = 0;
2436                 } while (!success && sl != r10_bio->read_slot);
2437                 rcu_read_unlock();
2438
2439                 if (!success) {
2440                         /* Cannot read from anywhere, just mark the block
2441                          * as bad on the first device to discourage future
2442                          * reads.
2443                          */
2444                         int dn = r10_bio->devs[r10_bio->read_slot].devnum;
2445                         rdev = conf->mirrors[dn].rdev;
2446
2447                         if (!rdev_set_badblocks(
2448                                     rdev,
2449                                     r10_bio->devs[r10_bio->read_slot].addr
2450                                     + sect,
2451                                     s, 0)) {
2452                                 md_error(mddev, rdev);
2453                                 r10_bio->devs[r10_bio->read_slot].bio
2454                                         = IO_BLOCKED;
2455                         }
2456                         break;
2457                 }
2458
2459                 start = sl;
2460                 /* write it back and re-read */
2461                 rcu_read_lock();
2462                 while (sl != r10_bio->read_slot) {
2463                         char b[BDEVNAME_SIZE];
2464
2465                         if (sl==0)
2466                                 sl = conf->copies;
2467                         sl--;
2468                         d = r10_bio->devs[sl].devnum;
2469                         rdev = rcu_dereference(conf->mirrors[d].rdev);
2470                         if (!rdev ||
2471                             test_bit(Unmerged, &rdev->flags) ||
2472                             !test_bit(In_sync, &rdev->flags))
2473                                 continue;
2474
2475                         atomic_inc(&rdev->nr_pending);
2476                         rcu_read_unlock();
2477                         if (r10_sync_page_io(rdev,
2478                                              r10_bio->devs[sl].addr +
2479                                              sect,
2480                                              s, conf->tmppage, WRITE)
2481                             == 0) {
2482                                 /* Well, this device is dead */
2483                                 printk(KERN_NOTICE
2484                                        "md/raid10:%s: read correction "
2485                                        "write failed"
2486                                        " (%d sectors at %llu on %s)\n",
2487                                        mdname(mddev), s,
2488                                        (unsigned long long)(
2489                                                sect +
2490                                                choose_data_offset(r10_bio,
2491                                                                   rdev)),
2492                                        bdevname(rdev->bdev, b));
2493                                 printk(KERN_NOTICE "md/raid10:%s: %s: failing "
2494                                        "drive\n",
2495                                        mdname(mddev),
2496                                        bdevname(rdev->bdev, b));
2497                         }
2498                         rdev_dec_pending(rdev, mddev);
2499                         rcu_read_lock();
2500                 }
2501                 sl = start;
2502                 while (sl != r10_bio->read_slot) {
2503                         char b[BDEVNAME_SIZE];
2504
2505                         if (sl==0)
2506                                 sl = conf->copies;
2507                         sl--;
2508                         d = r10_bio->devs[sl].devnum;
2509                         rdev = rcu_dereference(conf->mirrors[d].rdev);
2510                         if (!rdev ||
2511                             !test_bit(In_sync, &rdev->flags))
2512                                 continue;
2513
2514                         atomic_inc(&rdev->nr_pending);
2515                         rcu_read_unlock();
2516                         switch (r10_sync_page_io(rdev,
2517                                              r10_bio->devs[sl].addr +
2518                                              sect,
2519                                              s, conf->tmppage,
2520                                                  READ)) {
2521                         case 0:
2522                                 /* Well, this device is dead */
2523                                 printk(KERN_NOTICE
2524                                        "md/raid10:%s: unable to read back "
2525                                        "corrected sectors"
2526                                        " (%d sectors at %llu on %s)\n",
2527                                        mdname(mddev), s,
2528                                        (unsigned long long)(
2529                                                sect +
2530                                                choose_data_offset(r10_bio, rdev)),
2531                                        bdevname(rdev->bdev, b));
2532                                 printk(KERN_NOTICE "md/raid10:%s: %s: failing "
2533                                        "drive\n",
2534                                        mdname(mddev),
2535                                        bdevname(rdev->bdev, b));
2536                                 break;
2537                         case 1:
2538                                 printk(KERN_INFO
2539                                        "md/raid10:%s: read error corrected"
2540                                        " (%d sectors at %llu on %s)\n",
2541                                        mdname(mddev), s,
2542                                        (unsigned long long)(
2543                                                sect +
2544                                                choose_data_offset(r10_bio, rdev)),
2545                                        bdevname(rdev->bdev, b));
2546                                 atomic_add(s, &rdev->corrected_errors);
2547                         }
2548
2549                         rdev_dec_pending(rdev, mddev);
2550                         rcu_read_lock();
2551                 }
2552                 rcu_read_unlock();
2553
2554                 sectors -= s;
2555                 sect += s;
2556         }
2557 }
2558
2559 static int narrow_write_error(struct r10bio *r10_bio, int i)
2560 {
2561         struct bio *bio = r10_bio->master_bio;
2562         struct mddev *mddev = r10_bio->mddev;
2563         struct r10conf *conf = mddev->private;
2564         struct md_rdev *rdev = conf->mirrors[r10_bio->devs[i].devnum].rdev;
2565         /* bio has the data to be written to slot 'i' where
2566          * we just recently had a write error.
2567          * We repeatedly clone the bio and trim down to one block,
2568          * then try the write.  Where the write fails we record
2569          * a bad block.
2570          * It is conceivable that the bio doesn't exactly align with
2571          * blocks.  We must handle this.
2572          *
2573          * We currently own a reference to the rdev.
2574          */
2575
2576         int block_sectors;
2577         sector_t sector;
2578         int sectors;
2579         int sect_to_write = r10_bio->sectors;
2580         int ok = 1;
2581
2582         if (rdev->badblocks.shift < 0)
2583                 return 0;
2584
2585         block_sectors = 1 << rdev->badblocks.shift;
2586         sector = r10_bio->sector;
2587         sectors = ((r10_bio->sector + block_sectors)
2588                    & ~(sector_t)(block_sectors - 1))
2589                 - sector;
2590
2591         while (sect_to_write) {
2592                 struct bio *wbio;
2593                 if (sectors > sect_to_write)
2594                         sectors = sect_to_write;
2595                 /* Write at 'sector' for 'sectors' */
2596                 wbio = bio_clone_mddev(bio, GFP_NOIO, mddev);
2597                 md_trim_bio(wbio, sector - bio->bi_sector, sectors);
2598                 wbio->bi_sector = (r10_bio->devs[i].addr+
2599                                    choose_data_offset(r10_bio, rdev) +
2600                                    (sector - r10_bio->sector));
2601                 wbio->bi_bdev = rdev->bdev;
2602                 if (submit_bio_wait(WRITE, wbio) == 0)
2603                         /* Failure! */
2604                         ok = rdev_set_badblocks(rdev, sector,
2605                                                 sectors, 0)
2606                                 && ok;
2607
2608                 bio_put(wbio);
2609                 sect_to_write -= sectors;
2610                 sector += sectors;
2611                 sectors = block_sectors;
2612         }
2613         return ok;
2614 }
2615
2616 static void handle_read_error(struct mddev *mddev, struct r10bio *r10_bio)
2617 {
2618         int slot = r10_bio->read_slot;
2619         struct bio *bio;
2620         struct r10conf *conf = mddev->private;
2621         struct md_rdev *rdev = r10_bio->devs[slot].rdev;
2622         char b[BDEVNAME_SIZE];
2623         unsigned long do_sync;
2624         int max_sectors;
2625
2626         /* we got a read error. Maybe the drive is bad.  Maybe just
2627          * the block and we can fix it.
2628          * We freeze all other IO, and try reading the block from
2629          * other devices.  When we find one, we re-write
2630          * and check it that fixes the read error.
2631          * This is all done synchronously while the array is
2632          * frozen.
2633          */
2634         bio = r10_bio->devs[slot].bio;
2635         bdevname(bio->bi_bdev, b);
2636         bio_put(bio);
2637         r10_bio->devs[slot].bio = NULL;
2638
2639         if (mddev->ro == 0) {
2640                 freeze_array(conf, 1);
2641                 fix_read_error(conf, mddev, r10_bio);
2642                 unfreeze_array(conf);
2643         } else
2644                 r10_bio->devs[slot].bio = IO_BLOCKED;
2645
2646         rdev_dec_pending(rdev, mddev);
2647
2648 read_more:
2649         rdev = read_balance(conf, r10_bio, &max_sectors);
2650         if (rdev == NULL) {
2651                 printk(KERN_ALERT "md/raid10:%s: %s: unrecoverable I/O"
2652                        " read error for block %llu\n",
2653                        mdname(mddev), b,
2654                        (unsigned long long)r10_bio->sector);
2655                 raid_end_bio_io(r10_bio);
2656                 return;
2657         }
2658
2659         do_sync = (r10_bio->master_bio->bi_rw & REQ_SYNC);
2660         slot = r10_bio->read_slot;
2661         printk_ratelimited(
2662                 KERN_ERR
2663                 "md/raid10:%s: %s: redirecting "
2664                 "sector %llu to another mirror\n",
2665                 mdname(mddev),
2666                 bdevname(rdev->bdev, b),
2667                 (unsigned long long)r10_bio->sector);
2668         bio = bio_clone_mddev(r10_bio->master_bio,
2669                               GFP_NOIO, mddev);
2670         md_trim_bio(bio,
2671                     r10_bio->sector - bio->bi_sector,
2672                     max_sectors);
2673         r10_bio->devs[slot].bio = bio;
2674         r10_bio->devs[slot].rdev = rdev;
2675         bio->bi_sector = r10_bio->devs[slot].addr
2676                 + choose_data_offset(r10_bio, rdev);
2677         bio->bi_bdev = rdev->bdev;
2678         bio->bi_rw = READ | do_sync;
2679         bio->bi_private = r10_bio;
2680         bio->bi_end_io = raid10_end_read_request;
2681         if (max_sectors < r10_bio->sectors) {
2682                 /* Drat - have to split this up more */
2683                 struct bio *mbio = r10_bio->master_bio;
2684                 int sectors_handled =
2685                         r10_bio->sector + max_sectors
2686                         - mbio->bi_sector;
2687                 r10_bio->sectors = max_sectors;
2688                 spin_lock_irq(&conf->device_lock);
2689                 if (mbio->bi_phys_segments == 0)
2690                         mbio->bi_phys_segments = 2;
2691                 else
2692                         mbio->bi_phys_segments++;
2693                 spin_unlock_irq(&conf->device_lock);
2694                 generic_make_request(bio);
2695
2696                 r10_bio = mempool_alloc(conf->r10bio_pool,
2697                                         GFP_NOIO);
2698                 r10_bio->master_bio = mbio;
2699                 r10_bio->sectors = bio_sectors(mbio) - sectors_handled;
2700                 r10_bio->state = 0;
2701                 set_bit(R10BIO_ReadError,
2702                         &r10_bio->state);
2703                 r10_bio->mddev = mddev;
2704                 r10_bio->sector = mbio->bi_sector
2705                         + sectors_handled;
2706
2707                 goto read_more;
2708         } else
2709                 generic_make_request(bio);
2710 }
2711
2712 static void handle_write_completed(struct r10conf *conf, struct r10bio *r10_bio)
2713 {
2714         /* Some sort of write request has finished and it
2715          * succeeded in writing where we thought there was a
2716          * bad block.  So forget the bad block.
2717          * Or possibly if failed and we need to record
2718          * a bad block.
2719          */
2720         int m;
2721         struct md_rdev *rdev;
2722
2723         if (test_bit(R10BIO_IsSync, &r10_bio->state) ||
2724             test_bit(R10BIO_IsRecover, &r10_bio->state)) {
2725                 for (m = 0; m < conf->copies; m++) {
2726                         int dev = r10_bio->devs[m].devnum;
2727                         rdev = conf->mirrors[dev].rdev;
2728                         if (r10_bio->devs[m].bio == NULL)
2729                                 continue;
2730                         if (test_bit(BIO_UPTODATE,
2731                                      &r10_bio->devs[m].bio->bi_flags)) {
2732                                 rdev_clear_badblocks(
2733                                         rdev,
2734                                         r10_bio->devs[m].addr,
2735                                         r10_bio->sectors, 0);
2736                         } else {
2737                                 if (!rdev_set_badblocks(
2738                                             rdev,
2739                                             r10_bio->devs[m].addr,
2740                                             r10_bio->sectors, 0))
2741                                         md_error(conf->mddev, rdev);
2742                         }
2743                         rdev = conf->mirrors[dev].replacement;
2744                         if (r10_bio->devs[m].repl_bio == NULL)
2745                                 continue;
2746                         if (test_bit(BIO_UPTODATE,
2747                                      &r10_bio->devs[m].repl_bio->bi_flags)) {
2748                                 rdev_clear_badblocks(
2749                                         rdev,
2750                                         r10_bio->devs[m].addr,
2751                                         r10_bio->sectors, 0);
2752                         } else {
2753                                 if (!rdev_set_badblocks(
2754                                             rdev,
2755                                             r10_bio->devs[m].addr,
2756                                             r10_bio->sectors, 0))
2757                                         md_error(conf->mddev, rdev);
2758                         }
2759                 }
2760                 put_buf(r10_bio);
2761         } else {
2762                 for (m = 0; m < conf->copies; m++) {
2763                         int dev = r10_bio->devs[m].devnum;
2764                         struct bio *bio = r10_bio->devs[m].bio;
2765                         rdev = conf->mirrors[dev].rdev;
2766                         if (bio == IO_MADE_GOOD) {
2767                                 rdev_clear_badblocks(
2768                                         rdev,
2769                                         r10_bio->devs[m].addr,
2770                                         r10_bio->sectors, 0);
2771                                 rdev_dec_pending(rdev, conf->mddev);
2772                         } else if (bio != NULL &&
2773                                    !test_bit(BIO_UPTODATE, &bio->bi_flags)) {
2774                                 if (!narrow_write_error(r10_bio, m)) {
2775                                         md_error(conf->mddev, rdev);
2776                                         set_bit(R10BIO_Degraded,
2777                                                 &r10_bio->state);
2778                                 }
2779                                 rdev_dec_pending(rdev, conf->mddev);
2780                         }
2781                         bio = r10_bio->devs[m].repl_bio;
2782                         rdev = conf->mirrors[dev].replacement;
2783                         if (rdev && bio == IO_MADE_GOOD) {
2784                                 rdev_clear_badblocks(
2785                                         rdev,
2786                                         r10_bio->devs[m].addr,
2787                                         r10_bio->sectors, 0);
2788                                 rdev_dec_pending(rdev, conf->mddev);
2789                         }
2790                 }
2791                 if (test_bit(R10BIO_WriteError,
2792                              &r10_bio->state))
2793                         close_write(r10_bio);
2794                 raid_end_bio_io(r10_bio);
2795         }
2796 }
2797
2798 static void raid10d(struct md_thread *thread)
2799 {
2800         struct mddev *mddev = thread->mddev;
2801         struct r10bio *r10_bio;
2802         unsigned long flags;
2803         struct r10conf *conf = mddev->private;
2804         struct list_head *head = &conf->retry_list;
2805         struct blk_plug plug;
2806
2807         md_check_recovery(mddev);
2808
2809         blk_start_plug(&plug);
2810         for (;;) {
2811
2812                 flush_pending_writes(conf);
2813
2814                 spin_lock_irqsave(&conf->device_lock, flags);
2815                 if (list_empty(head)) {
2816                         spin_unlock_irqrestore(&conf->device_lock, flags);
2817                         break;
2818                 }
2819                 r10_bio = list_entry(head->prev, struct r10bio, retry_list);
2820                 list_del(head->prev);
2821                 conf->nr_queued--;
2822                 spin_unlock_irqrestore(&conf->device_lock, flags);
2823
2824                 mddev = r10_bio->mddev;
2825                 conf = mddev->private;
2826                 if (test_bit(R10BIO_MadeGood, &r10_bio->state) ||
2827                     test_bit(R10BIO_WriteError, &r10_bio->state))
2828                         handle_write_completed(conf, r10_bio);
2829                 else if (test_bit(R10BIO_IsReshape, &r10_bio->state))
2830                         reshape_request_write(mddev, r10_bio);
2831                 else if (test_bit(R10BIO_IsSync, &r10_bio->state))
2832                         sync_request_write(mddev, r10_bio);
2833                 else if (test_bit(R10BIO_IsRecover, &r10_bio->state))
2834                         recovery_request_write(mddev, r10_bio);
2835                 else if (test_bit(R10BIO_ReadError, &r10_bio->state))
2836                         handle_read_error(mddev, r10_bio);
2837                 else {
2838                         /* just a partial read to be scheduled from a
2839                          * separate context
2840                          */
2841                         int slot = r10_bio->read_slot;
2842                         generic_make_request(r10_bio->devs[slot].bio);
2843                 }
2844
2845                 cond_resched();
2846                 if (mddev->flags & ~(1<<MD_CHANGE_PENDING))
2847                         md_check_recovery(mddev);
2848         }
2849         blk_finish_plug(&plug);
2850 }
2851
2852
2853 static int init_resync(struct r10conf *conf)
2854 {
2855         int buffs;
2856         int i;
2857
2858         buffs = RESYNC_WINDOW / RESYNC_BLOCK_SIZE;
2859         BUG_ON(conf->r10buf_pool);
2860         conf->have_replacement = 0;
2861         for (i = 0; i < conf->geo.raid_disks; i++)
2862                 if (conf->mirrors[i].replacement)
2863                         conf->have_replacement = 1;
2864         conf->r10buf_pool = mempool_create(buffs, r10buf_pool_alloc, r10buf_pool_free, conf);
2865         if (!conf->r10buf_pool)
2866                 return -ENOMEM;
2867         conf->next_resync = 0;
2868         return 0;
2869 }
2870
2871 /*
2872  * perform a "sync" on one "block"
2873  *
2874  * We need to make sure that no normal I/O request - particularly write
2875  * requests - conflict with active sync requests.
2876  *
2877  * This is achieved by tracking pending requests and a 'barrier' concept
2878  * that can be installed to exclude normal IO requests.
2879  *
2880  * Resync and recovery are handled very differently.
2881  * We differentiate by looking at MD_RECOVERY_SYNC in mddev->recovery.
2882  *
2883  * For resync, we iterate over virtual addresses, read all copies,
2884  * and update if there are differences.  If only one copy is live,
2885  * skip it.
2886  * For recovery, we iterate over physical addresses, read a good
2887  * value for each non-in_sync drive, and over-write.
2888  *
2889  * So, for recovery we may have several outstanding complex requests for a
2890  * given address, one for each out-of-sync device.  We model this by allocating
2891  * a number of r10_bio structures, one for each out-of-sync device.
2892  * As we setup these structures, we collect all bio's together into a list
2893  * which we then process collectively to add pages, and then process again
2894  * to pass to generic_make_request.
2895  *
2896  * The r10_bio structures are linked using a borrowed master_bio pointer.
2897  * This link is counted in ->remaining.  When the r10_bio that points to NULL
2898  * has its remaining count decremented to 0, the whole complex operation
2899  * is complete.
2900  *
2901  */
2902
2903 static sector_t sync_request(struct mddev *mddev, sector_t sector_nr,
2904                              int *skipped, int go_faster)
2905 {
2906         struct r10conf *conf = mddev->private;
2907         struct r10bio *r10_bio;
2908         struct bio *biolist = NULL, *bio;
2909         sector_t max_sector, nr_sectors;
2910         int i;
2911         int max_sync;
2912         sector_t sync_blocks;
2913         sector_t sectors_skipped = 0;
2914         int chunks_skipped = 0;
2915         sector_t chunk_mask = conf->geo.chunk_mask;
2916
2917         if (!conf->r10buf_pool)
2918                 if (init_resync(conf))
2919                         return 0;
2920
2921         /*
2922          * Allow skipping a full rebuild for incremental assembly
2923          * of a clean array, like RAID1 does.
2924          */
2925         if (mddev->bitmap == NULL &&
2926             mddev->recovery_cp == MaxSector &&
2927             !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
2928             conf->fullsync == 0) {
2929                 *skipped = 1;
2930                 max_sector = mddev->dev_sectors;
2931                 if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ||
2932                     test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
2933                         max_sector = mddev->resync_max_sectors;
2934                 return max_sector - sector_nr;
2935         }
2936
2937  skipped:
2938         max_sector = mddev->dev_sectors;
2939         if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ||
2940             test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
2941                 max_sector = mddev->resync_max_sectors;
2942         if (sector_nr >= max_sector) {
2943                 /* If we aborted, we need to abort the
2944                  * sync on the 'current' bitmap chucks (there can
2945                  * be several when recovering multiple devices).
2946                  * as we may have started syncing it but not finished.
2947                  * We can find the current address in
2948                  * mddev->curr_resync, but for recovery,
2949                  * we need to convert that to several
2950                  * virtual addresses.
2951                  */
2952                 if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
2953                         end_reshape(conf);
2954                         return 0;
2955                 }
2956
2957                 if (mddev->curr_resync < max_sector) { /* aborted */
2958                         if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
2959                                 bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
2960                                                 &sync_blocks, 1);
2961                         else for (i = 0; i < conf->geo.raid_disks; i++) {
2962                                 sector_t sect =
2963                                         raid10_find_virt(conf, mddev->curr_resync, i);
2964                                 bitmap_end_sync(mddev->bitmap, sect,
2965                                                 &sync_blocks, 1);
2966                         }
2967                 } else {
2968                         /* completed sync */
2969                         if ((!mddev->bitmap || conf->fullsync)
2970                             && conf->have_replacement
2971                             && test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
2972                                 /* Completed a full sync so the replacements
2973                                  * are now fully recovered.
2974                                  */
2975                                 for (i = 0; i < conf->geo.raid_disks; i++)
2976                                         if (conf->mirrors[i].replacement)
2977                                                 conf->mirrors[i].replacement
2978                                                         ->recovery_offset
2979                                                         = MaxSector;
2980                         }
2981                         conf->fullsync = 0;
2982                 }
2983                 bitmap_close_sync(mddev->bitmap);
2984                 close_sync(conf);
2985                 *skipped = 1;
2986                 return sectors_skipped;
2987         }
2988
2989         if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
2990                 return reshape_request(mddev, sector_nr, skipped);
2991
2992         if (chunks_skipped >= conf->geo.raid_disks) {
2993                 /* if there has been nothing to do on any drive,
2994                  * then there is nothing to do at all..
2995                  */
2996                 *skipped = 1;
2997                 return (max_sector - sector_nr) + sectors_skipped;
2998         }
2999
3000         if (max_sector > mddev->resync_max)
3001                 max_sector = mddev->resync_max; /* Don't do IO beyond here */
3002
3003         /* make sure whole request will fit in a chunk - if chunks
3004          * are meaningful
3005          */
3006         if (conf->geo.near_copies < conf->geo.raid_disks &&
3007             max_sector > (sector_nr | chunk_mask))
3008                 max_sector = (sector_nr | chunk_mask) + 1;
3009         /*
3010          * If there is non-resync activity waiting for us then
3011          * put in a delay to throttle resync.
3012          */
3013         if (!go_faster && conf->nr_waiting)
3014                 msleep_interruptible(1000);
3015
3016         /* Again, very different code for resync and recovery.
3017          * Both must result in an r10bio with a list of bios that
3018          * have bi_end_io, bi_sector, bi_bdev set,
3019          * and bi_private set to the r10bio.
3020          * For recovery, we may actually create several r10bios
3021          * with 2 bios in each, that correspond to the bios in the main one.
3022          * In this case, the subordinate r10bios link back through a
3023          * borrowed master_bio pointer, and the counter in the master
3024          * includes a ref from each subordinate.
3025          */
3026         /* First, we decide what to do and set ->bi_end_io
3027          * To end_sync_read if we want to read, and
3028          * end_sync_write if we will want to write.
3029          */
3030
3031         max_sync = RESYNC_PAGES << (PAGE_SHIFT-9);
3032         if (!test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
3033                 /* recovery... the complicated one */
3034                 int j;
3035                 r10_bio = NULL;
3036
3037                 for (i = 0 ; i < conf->geo.raid_disks; i++) {
3038                         int still_degraded;
3039                         struct r10bio *rb2;
3040                         sector_t sect;
3041                         int must_sync;
3042                         int any_working;
3043                         struct raid10_info *mirror = &conf->mirrors[i];
3044
3045                         if ((mirror->rdev == NULL ||
3046                              test_bit(In_sync, &mirror->rdev->flags))
3047                             &&
3048                             (mirror->replacement == NULL ||
3049                              test_bit(Faulty,
3050                                       &mirror->replacement->flags)))
3051                                 continue;
3052
3053                         still_degraded = 0;
3054                         /* want to reconstruct this device */
3055                         rb2 = r10_bio;
3056                         sect = raid10_find_virt(conf, sector_nr, i);
3057                         if (sect >= mddev->resync_max_sectors) {
3058                                 /* last stripe is not complete - don't
3059                                  * try to recover this sector.
3060                                  */
3061                                 continue;
3062                         }
3063                         /* Unless we are doing a full sync, or a replacement
3064                          * we only need to recover the block if it is set in
3065                          * the bitmap
3066                          */
3067                         must_sync = bitmap_start_sync(mddev->bitmap, sect,
3068                                                       &sync_blocks, 1);
3069                         if (sync_blocks < max_sync)
3070                                 max_sync = sync_blocks;
3071                         if (!must_sync &&
3072                             mirror->replacement == NULL &&
3073                             !conf->fullsync) {
3074                                 /* yep, skip the sync_blocks here, but don't assume
3075                                  * that there will never be anything to do here
3076                                  */
3077                                 chunks_skipped = -1;
3078                                 continue;
3079                         }
3080
3081                         r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
3082                         raise_barrier(conf, rb2 != NULL);
3083                         atomic_set(&r10_bio->remaining, 0);
3084
3085                         r10_bio->master_bio = (struct bio*)rb2;
3086                         if (rb2)
3087                                 atomic_inc(&rb2->remaining);
3088                         r10_bio->mddev = mddev;
3089                         set_bit(R10BIO_IsRecover, &r10_bio->state);
3090                         r10_bio->sector = sect;
3091
3092                         raid10_find_phys(conf, r10_bio);
3093
3094                         /* Need to check if the array will still be
3095                          * degraded
3096                          */
3097                         for (j = 0; j < conf->geo.raid_disks; j++)
3098                                 if (conf->mirrors[j].rdev == NULL ||
3099                                     test_bit(Faulty, &conf->mirrors[j].rdev->flags)) {
3100                                         still_degraded = 1;
3101                                         break;
3102                                 }
3103
3104                         must_sync = bitmap_start_sync(mddev->bitmap, sect,
3105                                                       &sync_blocks, still_degraded);
3106
3107                         any_working = 0;
3108                         for (j=0; j<conf->copies;j++) {
3109                                 int k;
3110                                 int d = r10_bio->devs[j].devnum;
3111                                 sector_t from_addr, to_addr;
3112                                 struct md_rdev *rdev;
3113                                 sector_t sector, first_bad;
3114                                 int bad_sectors;
3115                                 if (!conf->mirrors[d].rdev ||
3116                                     !test_bit(In_sync, &conf->mirrors[d].rdev->flags))
3117                                         continue;
3118                                 /* This is where we read from */
3119                                 any_working = 1;
3120                                 rdev = conf->mirrors[d].rdev;
3121                                 sector = r10_bio->devs[j].addr;
3122
3123                                 if (is_badblock(rdev, sector, max_sync,
3124                                                 &first_bad, &bad_sectors)) {
3125                                         if (first_bad > sector)
3126                                                 max_sync = first_bad - sector;
3127                                         else {
3128                                                 bad_sectors -= (sector
3129                                                                 - first_bad);
3130                                                 if (max_sync > bad_sectors)
3131                                                         max_sync = bad_sectors;
3132                                                 continue;
3133                                         }
3134                                 }
3135                                 bio = r10_bio->devs[0].bio;
3136                                 bio_reset(bio);
3137                                 bio->bi_next = biolist;
3138                                 biolist = bio;
3139                                 bio->bi_private = r10_bio;
3140                                 bio->bi_end_io = end_sync_read;
3141                                 bio->bi_rw = READ;
3142                                 from_addr = r10_bio->devs[j].addr;
3143                                 bio->bi_sector = from_addr + rdev->data_offset;
3144                                 bio->bi_bdev = rdev->bdev;
3145                                 atomic_inc(&rdev->nr_pending);
3146                                 /* and we write to 'i' (if not in_sync) */
3147
3148                                 for (k=0; k<conf->copies; k++)
3149                                         if (r10_bio->devs[k].devnum == i)
3150                                                 break;
3151                                 BUG_ON(k == conf->copies);
3152                                 to_addr = r10_bio->devs[k].addr;
3153                                 r10_bio->devs[0].devnum = d;
3154                                 r10_bio->devs[0].addr = from_addr;
3155                                 r10_bio->devs[1].devnum = i;
3156                                 r10_bio->devs[1].addr = to_addr;
3157
3158                                 rdev = mirror->rdev;
3159                                 if (!test_bit(In_sync, &rdev->flags)) {
3160                                         bio = r10_bio->devs[1].bio;
3161                                         bio_reset(bio);
3162                                         bio->bi_next = biolist;
3163                                         biolist = bio;
3164                                         bio->bi_private = r10_bio;
3165                                         bio->bi_end_io = end_sync_write;
3166                                         bio->bi_rw = WRITE;
3167                                         bio->bi_sector = to_addr
3168                                                 + rdev->data_offset;
3169                                         bio->bi_bdev = rdev->bdev;
3170                                         atomic_inc(&r10_bio->remaining);
3171                                 } else
3172                                         r10_bio->devs[1].bio->bi_end_io = NULL;
3173
3174                                 /* and maybe write to replacement */
3175                                 bio = r10_bio->devs[1].repl_bio;
3176                                 if (bio)
3177                                         bio->bi_end_io = NULL;
3178                                 rdev = mirror->replacement;
3179                                 /* Note: if rdev != NULL, then bio
3180                                  * cannot be NULL as r10buf_pool_alloc will
3181                                  * have allocated it.
3182                                  * So the second test here is pointless.
3183                                  * But it keeps semantic-checkers happy, and
3184                                  * this comment keeps human reviewers
3185                                  * happy.
3186                                  */
3187                                 if (rdev == NULL || bio == NULL ||
3188                                     test_bit(Faulty, &rdev->flags))
3189                                         break;
3190                                 bio_reset(bio);
3191                                 bio->bi_next = biolist;
3192                                 biolist = bio;
3193                                 bio->bi_private = r10_bio;
3194                                 bio->bi_end_io = end_sync_write;
3195                                 bio->bi_rw = WRITE;
3196                                 bio->bi_sector = to_addr + rdev->data_offset;
3197                                 bio->bi_bdev = rdev->bdev;
3198                                 atomic_inc(&r10_bio->remaining);
3199                                 break;
3200                         }
3201                         if (j == conf->copies) {
3202                                 /* Cannot recover, so abort the recovery or
3203                                  * record a bad block */
3204                                 put_buf(r10_bio);
3205                                 if (rb2)
3206                                         atomic_dec(&rb2->remaining);
3207                                 r10_bio = rb2;
3208                                 if (any_working) {
3209                                         /* problem is that there are bad blocks
3210                                          * on other device(s)
3211                                          */
3212                                         int k;
3213                                         for (k = 0; k < conf->copies; k++)
3214                                                 if (r10_bio->devs[k].devnum == i)
3215                                                         break;
3216                                         if (!test_bit(In_sync,
3217                                                       &mirror->rdev->flags)
3218                                             && !rdev_set_badblocks(
3219                                                     mirror->rdev,
3220                                                     r10_bio->devs[k].addr,
3221                                                     max_sync, 0))
3222                                                 any_working = 0;
3223                                         if (mirror->replacement &&
3224                                             !rdev_set_badblocks(
3225                                                     mirror->replacement,
3226                                                     r10_bio->devs[k].addr,
3227                                                     max_sync, 0))
3228                                                 any_working = 0;
3229                                 }
3230                                 if (!any_working)  {
3231                                         if (!test_and_set_bit(MD_RECOVERY_INTR,
3232                                                               &mddev->recovery))
3233                                                 printk(KERN_INFO "md/raid10:%s: insufficient "
3234                                                        "working devices for recovery.\n",
3235                                                        mdname(mddev));
3236                                         mirror->recovery_disabled
3237                                                 = mddev->recovery_disabled;
3238                                 }
3239                                 break;
3240                         }
3241                 }
3242                 if (biolist == NULL) {
3243                         while (r10_bio) {
3244                                 struct r10bio *rb2 = r10_bio;
3245                                 r10_bio = (struct r10bio*) rb2->master_bio;
3246                                 rb2->master_bio = NULL;
3247                                 put_buf(rb2);
3248                         }
3249                         goto giveup;
3250                 }
3251         } else {
3252                 /* resync. Schedule a read for every block at this virt offset */
3253                 int count = 0;
3254
3255                 bitmap_cond_end_sync(mddev->bitmap, sector_nr);
3256
3257                 if (!bitmap_start_sync(mddev->bitmap, sector_nr,
3258                                        &sync_blocks, mddev->degraded) &&
3259                     !conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED,
3260                                                  &mddev->recovery)) {
3261                         /* We can skip this block */
3262                         *skipped = 1;
3263                         return sync_blocks + sectors_skipped;
3264                 }
3265                 if (sync_blocks < max_sync)
3266                         max_sync = sync_blocks;
3267                 r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
3268
3269                 r10_bio->mddev = mddev;
3270                 atomic_set(&r10_bio->remaining, 0);
3271                 raise_barrier(conf, 0);
3272                 conf->next_resync = sector_nr;
3273
3274                 r10_bio->master_bio = NULL;
3275                 r10_bio->sector = sector_nr;
3276                 set_bit(R10BIO_IsSync, &r10_bio->state);
3277                 raid10_find_phys(conf, r10_bio);
3278                 r10_bio->sectors = (sector_nr | chunk_mask) - sector_nr + 1;
3279
3280                 for (i = 0; i < conf->copies; i++) {
3281                         int d = r10_bio->devs[i].devnum;
3282                         sector_t first_bad, sector;
3283                         int bad_sectors;
3284
3285                         if (r10_bio->devs[i].repl_bio)
3286                                 r10_bio->devs[i].repl_bio->bi_end_io = NULL;
3287
3288                         bio = r10_bio->devs[i].bio;
3289                         bio_reset(bio);
3290                         clear_bit(BIO_UPTODATE, &bio->bi_flags);
3291                         if (conf->mirrors[d].rdev == NULL ||
3292                             test_bit(Faulty, &conf->mirrors[d].rdev->flags))
3293                                 continue;
3294                         sector = r10_bio->devs[i].addr;
3295                         if (is_badblock(conf->mirrors[d].rdev,
3296                                         sector, max_sync,
3297                                         &first_bad, &bad_sectors)) {
3298                                 if (first_bad > sector)
3299                                         max_sync = first_bad - sector;
3300                                 else {
3301                                         bad_sectors -= (sector - first_bad);
3302                                         if (max_sync > bad_sectors)
3303                                                 max_sync = bad_sectors;
3304                                         continue;
3305                                 }
3306                         }
3307                         atomic_inc(&conf->mirrors[d].rdev->nr_pending);
3308                         atomic_inc(&r10_bio->remaining);
3309                         bio->bi_next = biolist;
3310                         biolist = bio;
3311                         bio->bi_private = r10_bio;
3312                         bio->bi_end_io = end_sync_read;
3313                         bio->bi_rw = READ;
3314                         bio->bi_sector = sector +
3315                                 conf->mirrors[d].rdev->data_offset;
3316                         bio->bi_bdev = conf->mirrors[d].rdev->bdev;
3317                         count++;
3318
3319                         if (conf->mirrors[d].replacement == NULL ||
3320                             test_bit(Faulty,
3321                                      &conf->mirrors[d].replacement->flags))
3322                                 continue;
3323
3324                         /* Need to set up for writing to the replacement */
3325                         bio = r10_bio->devs[i].repl_bio;
3326                         bio_reset(bio);
3327                         clear_bit(BIO_UPTODATE, &bio->bi_flags);
3328
3329                         sector = r10_bio->devs[i].addr;
3330                         atomic_inc(&conf->mirrors[d].rdev->nr_pending);
3331                         bio->bi_next = biolist;
3332                         biolist = bio;
3333                         bio->bi_private = r10_bio;
3334                         bio->bi_end_io = end_sync_write;
3335                         bio->bi_rw = WRITE;
3336                         bio->bi_sector = sector +
3337                                 conf->mirrors[d].replacement->data_offset;
3338                         bio->bi_bdev = conf->mirrors[d].replacement->bdev;
3339                         count++;
3340                 }
3341
3342                 if (count < 2) {
3343                         for (i=0; i<conf->copies; i++) {
3344                                 int d = r10_bio->devs[i].devnum;
3345                                 if (r10_bio->devs[i].bio->bi_end_io)
3346                                         rdev_dec_pending(conf->mirrors[d].rdev,
3347                                                          mddev);
3348                                 if (r10_bio->devs[i].repl_bio &&
3349                                     r10_bio->devs[i].repl_bio->bi_end_io)
3350                                         rdev_dec_pending(
3351                                                 conf->mirrors[d].replacement,
3352                                                 mddev);
3353                         }
3354                         put_buf(r10_bio);
3355                         biolist = NULL;
3356                         goto giveup;
3357                 }
3358         }
3359
3360         nr_sectors = 0;
3361         if (sector_nr + max_sync < max_sector)
3362                 max_sector = sector_nr + max_sync;
3363         do {
3364                 struct page *page;
3365                 int len = PAGE_SIZE;
3366                 if (sector_nr + (len>>9) > max_sector)
3367                         len = (max_sector - sector_nr) << 9;
3368                 if (len == 0)
3369                         break;
3370                 for (bio= biolist ; bio ; bio=bio->bi_next) {
3371                         struct bio *bio2;
3372                         page = bio->bi_io_vec[bio->bi_vcnt].bv_page;
3373                         if (bio_add_page(bio, page, len, 0))
3374                                 continue;
3375
3376                         /* stop here */
3377                         bio->bi_io_vec[bio->bi_vcnt].bv_page = page;
3378                         for (bio2 = biolist;
3379                              bio2 && bio2 != bio;
3380                              bio2 = bio2->bi_next) {
3381                                 /* remove last page from this bio */
3382                                 bio2->bi_vcnt--;
3383                                 bio2->bi_size -= len;
3384                                 bio2->bi_flags &= ~(1<< BIO_SEG_VALID);
3385                         }
3386                         goto bio_full;
3387                 }
3388                 nr_sectors += len>>9;
3389                 sector_nr += len>>9;
3390         } while (biolist->bi_vcnt < RESYNC_PAGES);
3391  bio_full:
3392         r10_bio->sectors = nr_sectors;
3393
3394         while (biolist) {
3395                 bio = biolist;
3396                 biolist = biolist->bi_next;
3397
3398                 bio->bi_next = NULL;
3399                 r10_bio = bio->bi_private;
3400                 r10_bio->sectors = nr_sectors;
3401
3402                 if (bio->bi_end_io == end_sync_read) {
3403                         md_sync_acct(bio->bi_bdev, nr_sectors);
3404                         generic_make_request(bio);
3405                 }
3406         }
3407
3408         if (sectors_skipped)
3409                 /* pretend they weren't skipped, it makes
3410                  * no important difference in this case
3411                  */
3412                 md_done_sync(mddev, sectors_skipped, 1);
3413
3414         return sectors_skipped + nr_sectors;
3415  giveup:
3416         /* There is nowhere to write, so all non-sync
3417          * drives must be failed or in resync, all drives
3418          * have a bad block, so try the next chunk...
3419          */
3420         if (sector_nr + max_sync < max_sector)
3421                 max_sector = sector_nr + max_sync;
3422
3423         sectors_skipped += (max_sector - sector_nr);
3424         chunks_skipped ++;
3425         sector_nr = max_sector;
3426         goto skipped;
3427 }
3428
3429 static sector_t
3430 raid10_size(struct mddev *mddev, sector_t sectors, int raid_disks)
3431 {
3432         sector_t size;
3433         struct r10conf *conf = mddev->private;
3434
3435         if (!raid_disks)
3436                 raid_disks = min(conf->geo.raid_disks,
3437                                  conf->prev.raid_disks);
3438         if (!sectors)
3439                 sectors = conf->dev_sectors;
3440
3441         size = sectors >> conf->geo.chunk_shift;
3442         sector_div(size, conf->geo.far_copies);
3443         size = size * raid_disks;
3444         sector_div(size, conf->geo.near_copies);
3445
3446         return size << conf->geo.chunk_shift;
3447 }
3448
3449 static void calc_sectors(struct r10conf *conf, sector_t size)
3450 {
3451         /* Calculate the number of sectors-per-device that will
3452          * actually be used, and set conf->dev_sectors and
3453          * conf->stride
3454          */
3455
3456         size = size >> conf->geo.chunk_shift;
3457         sector_div(size, conf->geo.far_copies);
3458         size = size * conf->geo.raid_disks;
3459         sector_div(size, conf->geo.near_copies);
3460         /* 'size' is now the number of chunks in the array */
3461         /* calculate "used chunks per device" */
3462         size = size * conf->copies;
3463
3464         /* We need to round up when dividing by raid_disks to
3465          * get the stride size.
3466          */
3467         size = DIV_ROUND_UP_SECTOR_T(size, conf->geo.raid_disks);
3468
3469         conf->dev_sectors = size << conf->geo.chunk_shift;
3470
3471         if (conf->geo.far_offset)
3472                 conf->geo.stride = 1 << conf->geo.chunk_shift;
3473         else {
3474                 sector_div(size, conf->geo.far_copies);
3475                 conf->geo.stride = size << conf->geo.chunk_shift;
3476         }
3477 }
3478
3479 enum geo_type {geo_new, geo_old, geo_start};
3480 static int setup_geo(struct geom *geo, struct mddev *mddev, enum geo_type new)
3481 {
3482         int nc, fc, fo;
3483         int layout, chunk, disks;
3484         switch (new) {
3485         case geo_old:
3486                 layout = mddev->layout;
3487                 chunk = mddev->chunk_sectors;
3488                 disks = mddev->raid_disks - mddev->delta_disks;
3489                 break;
3490         case geo_new:
3491                 layout = mddev->new_layout;
3492                 chunk = mddev->new_chunk_sectors;
3493                 disks = mddev->raid_disks;
3494                 break;
3495         default: /* avoid 'may be unused' warnings */
3496         case geo_start: /* new when starting reshape - raid_disks not
3497                          * updated yet. */
3498                 layout = mddev->new_layout;
3499                 chunk = mddev->new_chunk_sectors;
3500                 disks = mddev->raid_disks + mddev->delta_disks;
3501                 break;
3502         }
3503         if (layout >> 18)
3504                 return -1;
3505         if (chunk < (PAGE_SIZE >> 9) ||
3506             !is_power_of_2(chunk))
3507                 return -2;
3508         nc = layout & 255;
3509         fc = (layout >> 8) & 255;
3510         fo = layout & (1<<16);
3511         geo->raid_disks = disks;
3512         geo->near_copies = nc;
3513         geo->far_copies = fc;
3514         geo->far_offset = fo;
3515         geo->far_set_size = (layout & (1<<17)) ? disks / fc : disks;
3516         geo->chunk_mask = chunk - 1;
3517         geo->chunk_shift = ffz(~chunk);
3518         return nc*fc;
3519 }
3520
3521 static struct r10conf *setup_conf(struct mddev *mddev)
3522 {
3523         struct r10conf *conf = NULL;
3524         int err = -EINVAL;
3525         struct geom geo;
3526         int copies;
3527
3528         copies = setup_geo(&geo, mddev, geo_new);
3529
3530         if (copies == -2) {
3531                 printk(KERN_ERR "md/raid10:%s: chunk size must be "
3532                        "at least PAGE_SIZE(%ld) and be a power of 2.\n",
3533                        mdname(mddev), PAGE_SIZE);
3534                 goto out;
3535         }
3536
3537         if (copies < 2 || copies > mddev->raid_disks) {
3538                 printk(KERN_ERR "md/raid10:%s: unsupported raid10 layout: 0x%8x\n",
3539                        mdname(mddev), mddev->new_layout);
3540                 goto out;
3541         }
3542
3543         err = -ENOMEM;
3544         conf = kzalloc(sizeof(struct r10conf), GFP_KERNEL);
3545         if (!conf)
3546                 goto out;
3547
3548         /* FIXME calc properly */
3549         conf->mirrors = kzalloc(sizeof(struct raid10_info)*(mddev->raid_disks +
3550                                                             max(0,mddev->delta_disks)),
3551                                 GFP_KERNEL);
3552         if (!conf->mirrors)
3553                 goto out;
3554
3555         conf->tmppage = alloc_page(GFP_KERNEL);
3556         if (!conf->tmppage)
3557                 goto out;
3558
3559         conf->geo = geo;
3560         conf->copies = copies;
3561         conf->r10bio_pool = mempool_create(NR_RAID10_BIOS, r10bio_pool_alloc,
3562                                            r10bio_pool_free, conf);
3563         if (!conf->r10bio_pool)
3564                 goto out;
3565
3566         calc_sectors(conf, mddev->dev_sectors);
3567         if (mddev->reshape_position == MaxSector) {
3568                 conf->prev = conf->geo;
3569                 conf->reshape_progress = MaxSector;
3570         } else {
3571                 if (setup_geo(&conf->prev, mddev, geo_old) != conf->copies) {
3572                         err = -EINVAL;
3573                         goto out;
3574                 }
3575                 conf->reshape_progress = mddev->reshape_position;
3576                 if (conf->prev.far_offset)
3577                         conf->prev.stride = 1 << conf->prev.chunk_shift;
3578                 else
3579                         /* far_copies must be 1 */
3580                         conf->prev.stride = conf->dev_sectors;
3581         }
3582         spin_lock_init(&conf->device_lock);
3583         INIT_LIST_HEAD(&conf->retry_list);
3584
3585         spin_lock_init(&conf->resync_lock);
3586         init_waitqueue_head(&conf->wait_barrier);
3587
3588         conf->thread = md_register_thread(raid10d, mddev, "raid10");
3589         if (!conf->thread)
3590                 goto out;
3591
3592         conf->mddev = mddev;
3593         return conf;
3594
3595  out:
3596         if (err == -ENOMEM)
3597                 printk(KERN_ERR "md/raid10:%s: couldn't allocate memory.\n",
3598                        mdname(mddev));
3599         if (conf) {
3600                 if (conf->r10bio_pool)
3601                         mempool_destroy(conf->r10bio_pool);
3602                 kfree(conf->mirrors);
3603                 safe_put_page(conf->tmppage);
3604                 kfree(conf);
3605         }
3606         return ERR_PTR(err);
3607 }
3608
3609 static int run(struct mddev *mddev)
3610 {
3611         struct r10conf *conf;
3612         int i, disk_idx, chunk_size;
3613         struct raid10_info *disk;
3614         struct md_rdev *rdev;
3615         sector_t size;
3616         sector_t min_offset_diff = 0;
3617         int first = 1;
3618         bool discard_supported = false;
3619
3620         if (mddev->private == NULL) {
3621                 conf = setup_conf(mddev);
3622                 if (IS_ERR(conf))
3623                         return PTR_ERR(conf);
3624                 mddev->private = conf;
3625         }
3626         conf = mddev->private;
3627         if (!conf)
3628                 goto out;
3629
3630         mddev->thread = conf->thread;
3631         conf->thread = NULL;
3632
3633         chunk_size = mddev->chunk_sectors << 9;
3634         if (mddev->queue) {
3635                 blk_queue_max_discard_sectors(mddev->queue,
3636                                               mddev->chunk_sectors);
3637                 blk_queue_max_write_same_sectors(mddev->queue, 0);
3638                 blk_queue_io_min(mddev->queue, chunk_size);
3639                 if (conf->geo.raid_disks % conf->geo.near_copies)
3640                         blk_queue_io_opt(mddev->queue, chunk_size * conf->geo.raid_disks);
3641                 else
3642                         blk_queue_io_opt(mddev->queue, chunk_size *
3643                                          (conf->geo.raid_disks / conf->geo.near_copies));
3644         }
3645
3646         rdev_for_each(rdev, mddev) {
3647                 long long diff;
3648                 struct request_queue *q;
3649
3650                 disk_idx = rdev->raid_disk;
3651                 if (disk_idx < 0)
3652                         continue;
3653                 if (disk_idx >= conf->geo.raid_disks &&
3654                     disk_idx >= conf->prev.raid_disks)
3655                         continue;
3656                 disk = conf->mirrors + disk_idx;
3657
3658                 if (test_bit(Replacement, &rdev->flags)) {
3659                         if (disk->replacement)
3660                                 goto out_free_conf;
3661                         disk->replacement = rdev;
3662                 } else {
3663                         if (disk->rdev)
3664                                 goto out_free_conf;
3665                         disk->rdev = rdev;
3666                 }
3667                 q = bdev_get_queue(rdev->bdev);
3668                 if (q->merge_bvec_fn)
3669                         mddev->merge_check_needed = 1;
3670                 diff = (rdev->new_data_offset - rdev->data_offset);
3671                 if (!mddev->reshape_backwards)
3672                         diff = -diff;
3673                 if (diff < 0)
3674                         diff = 0;
3675                 if (first || diff < min_offset_diff)
3676                         min_offset_diff = diff;
3677
3678                 if (mddev->gendisk)
3679                         disk_stack_limits(mddev->gendisk, rdev->bdev,
3680                                           rdev->data_offset << 9);
3681
3682                 disk->head_position = 0;
3683
3684                 if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
3685                         discard_supported = true;
3686         }
3687
3688         if (mddev->queue) {
3689                 if (discard_supported)
3690                         queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
3691                                                 mddev->queue);
3692                 else
3693                         queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD,
3694                                                   mddev->queue);
3695         }
3696         /* need to check that every block has at least one working mirror */
3697         if (!enough(conf, -1)) {
3698                 printk(KERN_ERR "md/raid10:%s: not enough operational mirrors.\n",
3699                        mdname(mddev));
3700                 goto out_free_conf;
3701         }
3702
3703         if (conf->reshape_progress != MaxSector) {
3704                 /* must ensure that shape change is supported */
3705                 if (conf->geo.far_copies != 1 &&
3706                     conf->geo.far_offset == 0)
3707                         goto out_free_conf;
3708                 if (conf->prev.far_copies != 1 &&
3709                     conf->geo.far_offset == 0)
3710                         goto out_free_conf;
3711         }
3712
3713         mddev->degraded = 0;
3714         for (i = 0;
3715              i < conf->geo.raid_disks
3716                      || i < conf->prev.raid_disks;
3717              i++) {
3718
3719                 disk = conf->mirrors + i;
3720
3721                 if (!disk->rdev && disk->replacement) {
3722                         /* The replacement is all we have - use it */
3723                         disk->rdev = disk->replacement;
3724                         disk->replacement = NULL;
3725                         clear_bit(Replacement, &disk->rdev->flags);
3726                 }
3727
3728                 if (!disk->rdev ||
3729                     !test_bit(In_sync, &disk->rdev->flags)) {
3730                         disk->head_position = 0;
3731                         mddev->degraded++;
3732                         if (disk->rdev)
3733                                 conf->fullsync = 1;
3734                 }
3735                 disk->recovery_disabled = mddev->recovery_disabled - 1;
3736         }
3737
3738         if (mddev->recovery_cp != MaxSector)
3739                 printk(KERN_NOTICE "md/raid10:%s: not clean"
3740                        " -- starting background reconstruction\n",
3741                        mdname(mddev));
3742         printk(KERN_INFO
3743                 "md/raid10:%s: active with %d out of %d devices\n",
3744                 mdname(mddev), conf->geo.raid_disks - mddev->degraded,
3745                 conf->geo.raid_disks);
3746         /*
3747          * Ok, everything is just fine now
3748          */
3749         mddev->dev_sectors = conf->dev_sectors;
3750         size = raid10_size(mddev, 0, 0);
3751         md_set_array_sectors(mddev, size);
3752         mddev->resync_max_sectors = size;
3753
3754         if (mddev->queue) {
3755                 int stripe = conf->geo.raid_disks *
3756                         ((mddev->chunk_sectors << 9) / PAGE_SIZE);
3757                 mddev->queue->backing_dev_info.congested_fn = raid10_congested;
3758                 mddev->queue->backing_dev_info.congested_data = mddev;
3759
3760                 /* Calculate max read-ahead size.
3761                  * We need to readahead at least twice a whole stripe....
3762                  * maybe...
3763                  */
3764                 stripe /= conf->geo.near_copies;
3765                 if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
3766                         mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
3767                 blk_queue_merge_bvec(mddev->queue, raid10_mergeable_bvec);
3768         }
3769
3770
3771         if (md_integrity_register(mddev))
3772                 goto out_free_conf;
3773
3774         if (conf->reshape_progress != MaxSector) {
3775                 unsigned long before_length, after_length;
3776
3777                 before_length = ((1 << conf->prev.chunk_shift) *
3778                                  conf->prev.far_copies);
3779                 after_length = ((1 << conf->geo.chunk_shift) *
3780                                 conf->geo.far_copies);
3781
3782                 if (max(before_length, after_length) > min_offset_diff) {
3783                         /* This cannot work */
3784                         printk("md/raid10: offset difference not enough to continue reshape\n");
3785                         goto out_free_conf;
3786                 }
3787                 conf->offset_diff = min_offset_diff;
3788
3789                 conf->reshape_safe = conf->reshape_progress;
3790                 clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
3791                 clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
3792                 set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
3793                 set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
3794                 mddev->sync_thread = md_register_thread(md_do_sync, mddev,
3795                                                         "reshape");
3796         }
3797
3798         return 0;
3799
3800 out_free_conf:
3801         md_unregister_thread(&mddev->thread);
3802         if (conf->r10bio_pool)
3803                 mempool_destroy(conf->r10bio_pool);
3804         safe_put_page(conf->tmppage);
3805         kfree(conf->mirrors);
3806         kfree(conf);
3807         mddev->private = NULL;
3808 out:
3809         return -EIO;
3810 }
3811
3812 static int stop(struct mddev *mddev)
3813 {
3814         struct r10conf *conf = mddev->private;
3815
3816         raise_barrier(conf, 0);
3817         lower_barrier(conf);
3818
3819         md_unregister_thread(&mddev->thread);
3820         if (mddev->queue)
3821                 /* the unplug fn references 'conf'*/
3822                 blk_sync_queue(mddev->queue);
3823
3824         if (conf->r10bio_pool)
3825                 mempool_destroy(conf->r10bio_pool);
3826         safe_put_page(conf->tmppage);
3827         kfree(conf->mirrors);
3828         kfree(conf);
3829         mddev->private = NULL;
3830         return 0;
3831 }
3832
3833 static void raid10_quiesce(struct mddev *mddev, int state)
3834 {
3835         struct r10conf *conf = mddev->private;
3836
3837         switch(state) {
3838         case 1:
3839                 raise_barrier(conf, 0);
3840                 break;
3841         case 0:
3842                 lower_barrier(conf);
3843                 break;
3844         }
3845 }
3846
3847 static int raid10_resize(struct mddev *mddev, sector_t sectors)
3848 {
3849         /* Resize of 'far' arrays is not supported.
3850          * For 'near' and 'offset' arrays we can set the
3851          * number of sectors used to be an appropriate multiple
3852          * of the chunk size.
3853          * For 'offset', this is far_copies*chunksize.
3854          * For 'near' the multiplier is the LCM of
3855          * near_copies and raid_disks.
3856          * So if far_copies > 1 && !far_offset, fail.
3857          * Else find LCM(raid_disks, near_copy)*far_copies and
3858          * multiply by chunk_size.  Then round to this number.
3859          * This is mostly done by raid10_size()
3860          */
3861         struct r10conf *conf = mddev->private;
3862         sector_t oldsize, size;
3863
3864         if (mddev->reshape_position != MaxSector)
3865                 return -EBUSY;
3866
3867         if (conf->geo.far_copies > 1 && !conf->geo.far_offset)
3868                 return -EINVAL;
3869
3870         oldsize = raid10_size(mddev, 0, 0);
3871         size = raid10_size(mddev, sectors, 0);
3872         if (mddev->external_size &&
3873             mddev->array_sectors > size)
3874                 return -EINVAL;
3875         if (mddev->bitmap) {
3876                 int ret = bitmap_resize(mddev->bitmap, size, 0, 0);
3877                 if (ret)
3878                         return ret;
3879         }
3880         md_set_array_sectors(mddev, size);
3881         set_capacity(mddev->gendisk, mddev->array_sectors);
3882         revalidate_disk(mddev->gendisk);
3883         if (sectors > mddev->dev_sectors &&
3884             mddev->recovery_cp > oldsize) {
3885                 mddev->recovery_cp = oldsize;
3886                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
3887         }
3888         calc_sectors(conf, sectors);
3889         mddev->dev_sectors = conf->dev_sectors;
3890         mddev->resync_max_sectors = size;
3891         return 0;
3892 }
3893
3894 static void *raid10_takeover_raid0(struct mddev *mddev)
3895 {
3896         struct md_rdev *rdev;
3897         struct r10conf *conf;
3898
3899         if (mddev->degraded > 0) {
3900                 printk(KERN_ERR "md/raid10:%s: Error: degraded raid0!\n",
3901                        mdname(mddev));
3902                 return ERR_PTR(-EINVAL);
3903         }
3904
3905         /* Set new parameters */
3906         mddev->new_level = 10;
3907         /* new layout: far_copies = 1, near_copies = 2 */
3908         mddev->new_layout = (1<<8) + 2;
3909         mddev->new_chunk_sectors = mddev->chunk_sectors;
3910         mddev->delta_disks = mddev->raid_disks;
3911         mddev->raid_disks *= 2;
3912         /* make sure it will be not marked as dirty */
3913         mddev->recovery_cp = MaxSector;
3914
3915         conf = setup_conf(mddev);
3916         if (!IS_ERR(conf)) {
3917                 rdev_for_each(rdev, mddev)
3918                         if (rdev->raid_disk >= 0)
3919                                 rdev->new_raid_disk = rdev->raid_disk * 2;
3920                 conf->barrier = 1;
3921         }
3922
3923         return conf;
3924 }
3925
3926 static void *raid10_takeover(struct mddev *mddev)
3927 {
3928         struct r0conf *raid0_conf;
3929
3930         /* raid10 can take over:
3931          *  raid0 - providing it has only two drives
3932          */
3933         if (mddev->level == 0) {
3934                 /* for raid0 takeover only one zone is supported */
3935                 raid0_conf = mddev->private;
3936                 if (raid0_conf->nr_strip_zones > 1) {
3937                         printk(KERN_ERR "md/raid10:%s: cannot takeover raid 0"
3938                                " with more than one zone.\n",
3939                                mdname(mddev));
3940                         return ERR_PTR(-EINVAL);
3941                 }
3942                 return raid10_takeover_raid0(mddev);
3943         }
3944         return ERR_PTR(-EINVAL);
3945 }
3946
3947 static int raid10_check_reshape(struct mddev *mddev)
3948 {
3949         /* Called when there is a request to change
3950          * - layout (to ->new_layout)
3951          * - chunk size (to ->new_chunk_sectors)
3952          * - raid_disks (by delta_disks)
3953          * or when trying to restart a reshape that was ongoing.
3954          *
3955          * We need to validate the request and possibly allocate
3956          * space if that might be an issue later.
3957          *
3958          * Currently we reject any reshape of a 'far' mode array,
3959          * allow chunk size to change if new is generally acceptable,
3960          * allow raid_disks to increase, and allow
3961          * a switch between 'near' mode and 'offset' mode.
3962          */
3963         struct r10conf *conf = mddev->private;
3964         struct geom geo;
3965
3966         if (conf->geo.far_copies != 1 && !conf->geo.far_offset)
3967                 return -EINVAL;
3968
3969         if (setup_geo(&geo, mddev, geo_start) != conf->copies)
3970                 /* mustn't change number of copies */
3971                 return -EINVAL;
3972         if (geo.far_copies > 1 && !geo.far_offset)
3973                 /* Cannot switch to 'far' mode */
3974                 return -EINVAL;
3975
3976         if (mddev->array_sectors & geo.chunk_mask)
3977                         /* not factor of array size */
3978                         return -EINVAL;
3979
3980         if (!enough(conf, -1))
3981                 return -EINVAL;
3982
3983         kfree(conf->mirrors_new);
3984         conf->mirrors_new = NULL;
3985         if (mddev->delta_disks > 0) {
3986                 /* allocate new 'mirrors' list */
3987                 conf->mirrors_new = kzalloc(
3988                         sizeof(struct raid10_info)
3989                         *(mddev->raid_disks +
3990                           mddev->delta_disks),
3991                         GFP_KERNEL);
3992                 if (!conf->mirrors_new)
3993                         return -ENOMEM;
3994         }
3995         return 0;
3996 }
3997
3998 /*
3999  * Need to check if array has failed when deciding whether to:
4000  *  - start an array
4001  *  - remove non-faulty devices
4002  *  - add a spare
4003  *  - allow a reshape
4004  * This determination is simple when no reshape is happening.
4005  * However if there is a reshape, we need to carefully check
4006  * both the before and after sections.
4007  * This is because some failed devices may only affect one
4008  * of the two sections, and some non-in_sync devices may
4009  * be insync in the section most affected by failed devices.
4010  */
4011 static int calc_degraded(struct r10conf *conf)
4012 {
4013         int degraded, degraded2;
4014         int i;
4015
4016         rcu_read_lock();
4017         degraded = 0;
4018         /* 'prev' section first */
4019         for (i = 0; i < conf->prev.raid_disks; i++) {
4020                 struct md_rdev *rdev = rcu_dereference(conf->mirrors[i].rdev);
4021                 if (!rdev || test_bit(Faulty, &rdev->flags))
4022                         degraded++;
4023                 else if (!test_bit(In_sync, &rdev->flags))
4024                         /* When we can reduce the number of devices in
4025                          * an array, this might not contribute to
4026                          * 'degraded'.  It does now.
4027                          */
4028                         degraded++;
4029         }
4030         rcu_read_unlock();
4031         if (conf->geo.raid_disks == conf->prev.raid_disks)
4032                 return degraded;
4033         rcu_read_lock();
4034         degraded2 = 0;
4035         for (i = 0; i < conf->geo.raid_disks; i++) {
4036                 struct md_rdev *rdev = rcu_dereference(conf->mirrors[i].rdev);
4037                 if (!rdev || test_bit(Faulty, &rdev->flags))
4038                         degraded2++;
4039                 else if (!test_bit(In_sync, &rdev->flags)) {
4040                         /* If reshape is increasing the number of devices,
4041                          * this section has already been recovered, so
4042                          * it doesn't contribute to degraded.
4043                          * else it does.
4044                          */
4045                         if (conf->geo.raid_disks <= conf->prev.raid_disks)
4046                                 degraded2++;
4047                 }
4048         }
4049         rcu_read_unlock();
4050         if (degraded2 > degraded)
4051                 return degraded2;
4052         return degraded;
4053 }
4054
4055 static int raid10_start_reshape(struct mddev *mddev)
4056 {
4057         /* A 'reshape' has been requested. This commits
4058          * the various 'new' fields and sets MD_RECOVER_RESHAPE
4059          * This also checks if there are enough spares and adds them
4060          * to the array.
4061          * We currently require enough spares to make the final
4062          * array non-degraded.  We also require that the difference
4063          * between old and new data_offset - on each device - is
4064          * enough that we never risk over-writing.
4065          */
4066
4067         unsigned long before_length, after_length;
4068         sector_t min_offset_diff = 0;
4069         int first = 1;
4070         struct geom new;
4071         struct r10conf *conf = mddev->private;
4072         struct md_rdev *rdev;
4073         int spares = 0;
4074         int ret;
4075
4076         if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
4077                 return -EBUSY;
4078
4079         if (setup_geo(&new, mddev, geo_start) != conf->copies)
4080                 return -EINVAL;
4081
4082         before_length = ((1 << conf->prev.chunk_shift) *
4083                          conf->prev.far_copies);
4084         after_length = ((1 << conf->geo.chunk_shift) *
4085                         conf->geo.far_copies);
4086
4087         rdev_for_each(rdev, mddev) {
4088                 if (!test_bit(In_sync, &rdev->flags)
4089                     && !test_bit(Faulty, &rdev->flags))
4090                         spares++;
4091                 if (rdev->raid_disk >= 0) {
4092                         long long diff = (rdev->new_data_offset
4093                                           - rdev->data_offset);
4094                         if (!mddev->reshape_backwards)
4095                                 diff = -diff;
4096                         if (diff < 0)
4097                                 diff = 0;
4098                         if (first || diff < min_offset_diff)
4099                                 min_offset_diff = diff;
4100                 }
4101         }
4102
4103         if (max(before_length, after_length) > min_offset_diff)
4104                 return -EINVAL;
4105
4106         if (spares < mddev->delta_disks)
4107                 return -EINVAL;
4108
4109         conf->offset_diff = min_offset_diff;
4110         spin_lock_irq(&conf->device_lock);
4111         if (conf->mirrors_new) {
4112                 memcpy(conf->mirrors_new, conf->mirrors,
4113                        sizeof(struct raid10_info)*conf->prev.raid_disks);
4114                 smp_mb();
4115                 kfree(conf->mirrors_old); /* FIXME and elsewhere */
4116                 conf->mirrors_old = conf->mirrors;
4117                 conf->mirrors = conf->mirrors_new;
4118                 conf->mirrors_new = NULL;
4119         }
4120         setup_geo(&conf->geo, mddev, geo_start);
4121         smp_mb();
4122         if (mddev->reshape_backwards) {
4123                 sector_t size = raid10_size(mddev, 0, 0);
4124                 if (size < mddev->array_sectors) {
4125                         spin_unlock_irq(&conf->device_lock);
4126                         printk(KERN_ERR "md/raid10:%s: array size must be reduce before number of disks\n",
4127                                mdname(mddev));
4128                         return -EINVAL;
4129                 }
4130                 mddev->resync_max_sectors = size;
4131                 conf->reshape_progress = size;
4132         } else
4133                 conf->reshape_progress = 0;
4134         spin_unlock_irq(&conf->device_lock);
4135
4136         if (mddev->delta_disks && mddev->bitmap) {
4137                 ret = bitmap_resize(mddev->bitmap,
4138                                     raid10_size(mddev, 0,
4139                                                 conf->geo.raid_disks),
4140                                     0, 0);
4141                 if (ret)
4142                         goto abort;
4143         }
4144         if (mddev->delta_disks > 0) {
4145                 rdev_for_each(rdev, mddev)
4146                         if (rdev->raid_disk < 0 &&
4147                             !test_bit(Faulty, &rdev->flags)) {
4148                                 if (raid10_add_disk(mddev, rdev) == 0) {
4149                                         if (rdev->raid_disk >=
4150                                             conf->prev.raid_disks)
4151                                                 set_bit(In_sync, &rdev->flags);
4152                                         else
4153                                                 rdev->recovery_offset = 0;
4154
4155                                         if (sysfs_link_rdev(mddev, rdev))
4156                                                 /* Failure here  is OK */;
4157                                 }
4158                         } else if (rdev->raid_disk >= conf->prev.raid_disks
4159                                    && !test_bit(Faulty, &rdev->flags)) {
4160                                 /* This is a spare that was manually added */
4161                                 set_bit(In_sync, &rdev->flags);
4162                         }
4163         }
4164         /* When a reshape changes the number of devices,
4165          * ->degraded is measured against the larger of the
4166          * pre and  post numbers.
4167          */
4168         spin_lock_irq(&conf->device_lock);
4169         mddev->degraded = calc_degraded(conf);
4170         spin_unlock_irq(&conf->device_lock);
4171         mddev->raid_disks = conf->geo.raid_disks;
4172         mddev->reshape_position = conf->reshape_progress;
4173         set_bit(MD_CHANGE_DEVS, &mddev->flags);
4174
4175         clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
4176         clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
4177         set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
4178         set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
4179
4180         mddev->sync_thread = md_register_thread(md_do_sync, mddev,
4181                                                 "reshape");
4182         if (!mddev->sync_thread) {
4183                 ret = -EAGAIN;
4184                 goto abort;
4185         }
4186         conf->reshape_checkpoint = jiffies;
4187         md_wakeup_thread(mddev->sync_thread);
4188         md_new_event(mddev);
4189         return 0;
4190
4191 abort:
4192         mddev->recovery = 0;
4193         spin_lock_irq(&conf->device_lock);
4194         conf->geo = conf->prev;
4195         mddev->raid_disks = conf->geo.raid_disks;
4196         rdev_for_each(rdev, mddev)
4197                 rdev->new_data_offset = rdev->data_offset;
4198         smp_wmb();
4199         conf->reshape_progress = MaxSector;
4200         mddev->reshape_position = MaxSector;
4201         spin_unlock_irq(&conf->device_lock);
4202         return ret;
4203 }
4204
4205 /* Calculate the last device-address that could contain
4206  * any block from the chunk that includes the array-address 's'
4207  * and report the next address.
4208  * i.e. the address returned will be chunk-aligned and after
4209  * any data that is in the chunk containing 's'.
4210  */
4211 static sector_t last_dev_address(sector_t s, struct geom *geo)
4212 {
4213         s = (s | geo->chunk_mask) + 1;
4214         s >>= geo->chunk_shift;
4215         s *= geo->near_copies;
4216         s = DIV_ROUND_UP_SECTOR_T(s, geo->raid_disks);
4217         s *= geo->far_copies;
4218         s <<= geo->chunk_shift;
4219         return s;
4220 }
4221
4222 /* Calculate the first device-address that could contain
4223  * any block from the chunk that includes the array-address 's'.
4224  * This too will be the start of a chunk
4225  */
4226 static sector_t first_dev_address(sector_t s, struct geom *geo)
4227 {
4228         s >>= geo->chunk_shift;
4229         s *= geo->near_copies;
4230         sector_div(s, geo->raid_disks);
4231         s *= geo->far_copies;
4232         s <<= geo->chunk_shift;
4233         return s;
4234 }
4235
4236 static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr,
4237                                 int *skipped)
4238 {
4239         /* We simply copy at most one chunk (smallest of old and new)
4240          * at a time, possibly less if that exceeds RESYNC_PAGES,
4241          * or we hit a bad block or something.
4242          * This might mean we pause for normal IO in the middle of
4243          * a chunk, but that is not a problem was mddev->reshape_position
4244          * can record any location.
4245          *
4246          * If we will want to write to a location that isn't
4247          * yet recorded as 'safe' (i.e. in metadata on disk) then
4248          * we need to flush all reshape requests and update the metadata.
4249          *
4250          * When reshaping forwards (e.g. to more devices), we interpret
4251          * 'safe' as the earliest block which might not have been copied
4252          * down yet.  We divide this by previous stripe size and multiply
4253          * by previous stripe length to get lowest device offset that we
4254          * cannot write to yet.
4255          * We interpret 'sector_nr' as an address that we want to write to.
4256          * From this we use last_device_address() to find where we might
4257          * write to, and first_device_address on the  'safe' position.
4258          * If this 'next' write position is after the 'safe' position,
4259          * we must update the metadata to increase the 'safe' position.
4260          *
4261          * When reshaping backwards, we round in the opposite direction
4262          * and perform the reverse test:  next write position must not be
4263          * less than current safe position.
4264          *
4265          * In all this the minimum difference in data offsets
4266          * (conf->offset_diff - always positive) allows a bit of slack,
4267          * so next can be after 'safe', but not by more than offset_disk
4268          *
4269          * We need to prepare all the bios here before we start any IO
4270          * to ensure the size we choose is acceptable to all devices.
4271          * The means one for each copy for write-out and an extra one for
4272          * read-in.
4273          * We store the read-in bio in ->master_bio and the others in
4274          * ->devs[x].bio and ->devs[x].repl_bio.
4275          */
4276         struct r10conf *conf = mddev->private;
4277         struct r10bio *r10_bio;
4278         sector_t next, safe, last;
4279         int max_sectors;
4280         int nr_sectors;
4281         int s;
4282         struct md_rdev *rdev;
4283         int need_flush = 0;
4284         struct bio *blist;
4285         struct bio *bio, *read_bio;
4286         int sectors_done = 0;
4287
4288         if (sector_nr == 0) {
4289                 /* If restarting in the middle, skip the initial sectors */
4290                 if (mddev->reshape_backwards &&
4291                     conf->reshape_progress < raid10_size(mddev, 0, 0)) {
4292                         sector_nr = (raid10_size(mddev, 0, 0)
4293                                      - conf->reshape_progress);
4294                 } else if (!mddev->reshape_backwards &&
4295                            conf->reshape_progress > 0)
4296                         sector_nr = conf->reshape_progress;
4297                 if (sector_nr) {
4298                         mddev->curr_resync_completed = sector_nr;
4299                         sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4300                         *skipped = 1;
4301                         return sector_nr;
4302                 }
4303         }
4304
4305         /* We don't use sector_nr to track where we are up to
4306          * as that doesn't work well for ->reshape_backwards.
4307          * So just use ->reshape_progress.
4308          */
4309         if (mddev->reshape_backwards) {
4310                 /* 'next' is the earliest device address that we might
4311                  * write to for this chunk in the new layout
4312                  */
4313                 next = first_dev_address(conf->reshape_progress - 1,
4314                                          &conf->geo);
4315
4316                 /* 'safe' is the last device address that we might read from
4317                  * in the old layout after a restart
4318                  */
4319                 safe = last_dev_address(conf->reshape_safe - 1,
4320                                         &conf->prev);
4321
4322                 if (next + conf->offset_diff < safe)
4323                         need_flush = 1;
4324
4325                 last = conf->reshape_progress - 1;
4326                 sector_nr = last & ~(sector_t)(conf->geo.chunk_mask
4327                                                & conf->prev.chunk_mask);
4328                 if (sector_nr + RESYNC_BLOCK_SIZE/512 < last)
4329                         sector_nr = last + 1 - RESYNC_BLOCK_SIZE/512;
4330         } else {
4331                 /* 'next' is after the last device address that we
4332                  * might write to for this chunk in the new layout
4333                  */
4334                 next = last_dev_address(conf->reshape_progress, &conf->geo);
4335
4336                 /* 'safe' is the earliest device address that we might
4337                  * read from in the old layout after a restart
4338                  */
4339                 safe = first_dev_address(conf->reshape_safe, &conf->prev);
4340
4341                 /* Need to update metadata if 'next' might be beyond 'safe'
4342                  * as that would possibly corrupt data
4343                  */
4344                 if (next > safe + conf->offset_diff)
4345                         need_flush = 1;
4346
4347                 sector_nr = conf->reshape_progress;
4348                 last  = sector_nr | (conf->geo.chunk_mask
4349                                      & conf->prev.chunk_mask);
4350
4351                 if (sector_nr + RESYNC_BLOCK_SIZE/512 <= last)
4352                         last = sector_nr + RESYNC_BLOCK_SIZE/512 - 1;
4353         }
4354
4355         if (need_flush ||
4356             time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
4357                 /* Need to update reshape_position in metadata */
4358                 wait_barrier(conf);
4359                 mddev->reshape_position = conf->reshape_progress;
4360                 if (mddev->reshape_backwards)
4361                         mddev->curr_resync_completed = raid10_size(mddev, 0, 0)
4362                                 - conf->reshape_progress;
4363                 else
4364                         mddev->curr_resync_completed = conf->reshape_progress;
4365                 conf->reshape_checkpoint = jiffies;
4366                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
4367                 md_wakeup_thread(mddev->thread);
4368                 wait_event(mddev->sb_wait, mddev->flags == 0 ||
4369                            kthread_should_stop());
4370                 conf->reshape_safe = mddev->reshape_position;
4371                 allow_barrier(conf);
4372         }
4373
4374 read_more:
4375         /* Now schedule reads for blocks from sector_nr to last */
4376         r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
4377         raise_barrier(conf, sectors_done != 0);
4378         atomic_set(&r10_bio->remaining, 0);
4379         r10_bio->mddev = mddev;
4380         r10_bio->sector = sector_nr;
4381         set_bit(R10BIO_IsReshape, &r10_bio->state);
4382         r10_bio->sectors = last - sector_nr + 1;
4383         rdev = read_balance(conf, r10_bio, &max_sectors);
4384         BUG_ON(!test_bit(R10BIO_Previous, &r10_bio->state));
4385
4386         if (!rdev) {
4387                 /* Cannot read from here, so need to record bad blocks
4388                  * on all the target devices.
4389                  */
4390                 // FIXME
4391                 set_bit(MD_RECOVERY_INTR, &mddev->recovery);
4392                 return sectors_done;
4393         }
4394
4395         read_bio = bio_alloc_mddev(GFP_KERNEL, RESYNC_PAGES, mddev);
4396
4397         read_bio->bi_bdev = rdev->bdev;
4398         read_bio->bi_sector = (r10_bio->devs[r10_bio->read_slot].addr
4399                                + rdev->data_offset);
4400         read_bio->bi_private = r10_bio;
4401         read_bio->bi_end_io = end_sync_read;
4402         read_bio->bi_rw = READ;
4403         read_bio->bi_flags &= ~(BIO_POOL_MASK - 1);
4404         read_bio->bi_flags |= 1 << BIO_UPTODATE;
4405         read_bio->bi_vcnt = 0;
4406         read_bio->bi_size = 0;
4407         r10_bio->master_bio = read_bio;
4408         r10_bio->read_slot = r10_bio->devs[r10_bio->read_slot].devnum;
4409
4410         /* Now find the locations in the new layout */
4411         __raid10_find_phys(&conf->geo, r10_bio);
4412
4413         blist = read_bio;
4414         read_bio->bi_next = NULL;
4415
4416         for (s = 0; s < conf->copies*2; s++) {
4417                 struct bio *b;
4418                 int d = r10_bio->devs[s/2].devnum;
4419                 struct md_rdev *rdev2;
4420                 if (s&1) {
4421                         rdev2 = conf->mirrors[d].replacement;
4422                         b = r10_bio->devs[s/2].repl_bio;
4423                 } else {
4424                         rdev2 = conf->mirrors[d].rdev;
4425                         b = r10_bio->devs[s/2].bio;
4426                 }
4427                 if (!rdev2 || test_bit(Faulty, &rdev2->flags))
4428                         continue;
4429
4430                 bio_reset(b);
4431                 b->bi_bdev = rdev2->bdev;
4432                 b->bi_sector = r10_bio->devs[s/2].addr + rdev2->new_data_offset;
4433                 b->bi_private = r10_bio;
4434                 b->bi_end_io = end_reshape_write;
4435                 b->bi_rw = WRITE;
4436                 b->bi_next = blist;
4437                 blist = b;
4438         }
4439
4440         /* Now add as many pages as possible to all of these bios. */
4441
4442         nr_sectors = 0;
4443         for (s = 0 ; s < max_sectors; s += PAGE_SIZE >> 9) {
4444                 struct page *page = r10_bio->devs[0].bio->bi_io_vec[s/(PAGE_SIZE>>9)].bv_page;
4445                 int len = (max_sectors - s) << 9;
4446                 if (len > PAGE_SIZE)
4447                         len = PAGE_SIZE;
4448                 for (bio = blist; bio ; bio = bio->bi_next) {
4449                         struct bio *bio2;
4450                         if (bio_add_page(bio, page, len, 0))
4451                                 continue;
4452
4453                         /* Didn't fit, must stop */
4454                         for (bio2 = blist;
4455                              bio2 && bio2 != bio;
4456                              bio2 = bio2->bi_next) {
4457                                 /* Remove last page from this bio */
4458                                 bio2->bi_vcnt--;
4459                                 bio2->bi_size -= len;
4460                                 bio2->bi_flags &= ~(1<<BIO_SEG_VALID);
4461                         }
4462                         goto bio_full;
4463                 }
4464                 sector_nr += len >> 9;
4465                 nr_sectors += len >> 9;
4466         }
4467 bio_full:
4468         r10_bio->sectors = nr_sectors;
4469
4470         /* Now submit the read */
4471         md_sync_acct(read_bio->bi_bdev, r10_bio->sectors);
4472         atomic_inc(&r10_bio->remaining);
4473         read_bio->bi_next = NULL;
4474         generic_make_request(read_bio);
4475         sector_nr += nr_sectors;
4476         sectors_done += nr_sectors;
4477         if (sector_nr <= last)
4478                 goto read_more;
4479
4480         /* Now that we have done the whole section we can
4481          * update reshape_progress
4482          */
4483         if (mddev->reshape_backwards)
4484                 conf->reshape_progress -= sectors_done;
4485         else
4486                 conf->reshape_progress += sectors_done;
4487
4488         return sectors_done;
4489 }
4490
4491 static void end_reshape_request(struct r10bio *r10_bio);
4492 static int handle_reshape_read_error(struct mddev *mddev,
4493                                      struct r10bio *r10_bio);
4494 static void reshape_request_write(struct mddev *mddev, struct r10bio *r10_bio)
4495 {
4496         /* Reshape read completed.  Hopefully we have a block
4497          * to write out.
4498          * If we got a read error then we do sync 1-page reads from
4499          * elsewhere until we find the data - or give up.
4500          */
4501         struct r10conf *conf = mddev->private;
4502         int s;
4503
4504         if (!test_bit(R10BIO_Uptodate, &r10_bio->state))
4505                 if (handle_reshape_read_error(mddev, r10_bio) < 0) {
4506                         /* Reshape has been aborted */
4507                         md_done_sync(mddev, r10_bio->sectors, 0);
4508                         return;
4509                 }
4510
4511         /* We definitely have the data in the pages, schedule the
4512          * writes.
4513          */
4514         atomic_set(&r10_bio->remaining, 1);
4515         for (s = 0; s < conf->copies*2; s++) {
4516                 struct bio *b;
4517                 int d = r10_bio->devs[s/2].devnum;
4518                 struct md_rdev *rdev;
4519                 if (s&1) {
4520                         rdev = conf->mirrors[d].replacement;
4521                         b = r10_bio->devs[s/2].repl_bio;
4522                 } else {
4523                         rdev = conf->mirrors[d].rdev;
4524                         b = r10_bio->devs[s/2].bio;
4525                 }
4526                 if (!rdev || test_bit(Faulty, &rdev->flags))
4527                         continue;
4528                 atomic_inc(&rdev->nr_pending);
4529                 md_sync_acct(b->bi_bdev, r10_bio->sectors);
4530                 atomic_inc(&r10_bio->remaining);
4531                 b->bi_next = NULL;
4532                 generic_make_request(b);
4533         }
4534         end_reshape_request(r10_bio);
4535 }
4536
4537 static void end_reshape(struct r10conf *conf)
4538 {
4539         if (test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery))
4540                 return;
4541
4542         spin_lock_irq(&conf->device_lock);
4543         conf->prev = conf->geo;
4544         md_finish_reshape(conf->mddev);
4545         smp_wmb();
4546         conf->reshape_progress = MaxSector;
4547         spin_unlock_irq(&conf->device_lock);
4548
4549         /* read-ahead size must cover two whole stripes, which is
4550          * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
4551          */
4552         if (conf->mddev->queue) {
4553                 int stripe = conf->geo.raid_disks *
4554                         ((conf->mddev->chunk_sectors << 9) / PAGE_SIZE);
4555                 stripe /= conf->geo.near_copies;
4556                 if (conf->mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
4557                         conf->mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
4558         }
4559         conf->fullsync = 0;
4560 }
4561
4562
4563 static int handle_reshape_read_error(struct mddev *mddev,
4564                                      struct r10bio *r10_bio)
4565 {
4566         /* Use sync reads to get the blocks from somewhere else */
4567         int sectors = r10_bio->sectors;
4568         struct r10conf *conf = mddev->private;
4569         struct {
4570                 struct r10bio r10_bio;
4571                 struct r10dev devs[conf->copies];
4572         } on_stack;
4573         struct r10bio *r10b = &on_stack.r10_bio;
4574         int slot = 0;
4575         int idx = 0;
4576         struct bio_vec *bvec = r10_bio->master_bio->bi_io_vec;
4577
4578         r10b->sector = r10_bio->sector;
4579         __raid10_find_phys(&conf->prev, r10b);
4580
4581         while (sectors) {
4582                 int s = sectors;
4583                 int success = 0;
4584                 int first_slot = slot;
4585
4586                 if (s > (PAGE_SIZE >> 9))
4587                         s = PAGE_SIZE >> 9;
4588
4589                 while (!success) {
4590                         int d = r10b->devs[slot].devnum;
4591                         struct md_rdev *rdev = conf->mirrors[d].rdev;
4592                         sector_t addr;
4593                         if (rdev == NULL ||
4594                             test_bit(Faulty, &rdev->flags) ||
4595                             !test_bit(In_sync, &rdev->flags))
4596                                 goto failed;
4597
4598                         addr = r10b->devs[slot].addr + idx * PAGE_SIZE;
4599                         success = sync_page_io(rdev,
4600                                                addr,
4601                                                s << 9,
4602                                                bvec[idx].bv_page,
4603                                                READ, false);
4604                         if (success)
4605                                 break;
4606                 failed:
4607                         slot++;
4608                         if (slot >= conf->copies)
4609                                 slot = 0;
4610                         if (slot == first_slot)
4611                                 break;
4612                 }
4613                 if (!success) {
4614                         /* couldn't read this block, must give up */
4615                         set_bit(MD_RECOVERY_INTR,
4616                                 &mddev->recovery);
4617                         return -EIO;
4618                 }
4619                 sectors -= s;
4620                 idx++;
4621         }
4622         return 0;
4623 }
4624
4625 static void end_reshape_write(struct bio *bio, int error)
4626 {
4627         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
4628         struct r10bio *r10_bio = bio->bi_private;
4629         struct mddev *mddev = r10_bio->mddev;
4630         struct r10conf *conf = mddev->private;
4631         int d;
4632         int slot;
4633         int repl;
4634         struct md_rdev *rdev = NULL;
4635
4636         d = find_bio_disk(conf, r10_bio, bio, &slot, &repl);
4637         if (repl)
4638                 rdev = conf->mirrors[d].replacement;
4639         if (!rdev) {
4640                 smp_mb();
4641                 rdev = conf->mirrors[d].rdev;
4642         }
4643
4644         if (!uptodate) {
4645                 /* FIXME should record badblock */
4646                 md_error(mddev, rdev);
4647         }
4648
4649         rdev_dec_pending(rdev, mddev);
4650         end_reshape_request(r10_bio);
4651 }
4652
4653 static void end_reshape_request(struct r10bio *r10_bio)
4654 {
4655         if (!atomic_dec_and_test(&r10_bio->remaining))
4656                 return;
4657         md_done_sync(r10_bio->mddev, r10_bio->sectors, 1);
4658         bio_put(r10_bio->master_bio);
4659         put_buf(r10_bio);
4660 }
4661
4662 static void raid10_finish_reshape(struct mddev *mddev)
4663 {
4664         struct r10conf *conf = mddev->private;
4665
4666         if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
4667                 return;
4668
4669         if (mddev->delta_disks > 0) {
4670                 sector_t size = raid10_size(mddev, 0, 0);
4671                 md_set_array_sectors(mddev, size);
4672                 if (mddev->recovery_cp > mddev->resync_max_sectors) {
4673                         mddev->recovery_cp = mddev->resync_max_sectors;
4674                         set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
4675                 }
4676                 mddev->resync_max_sectors = size;
4677                 set_capacity(mddev->gendisk, mddev->array_sectors);
4678                 revalidate_disk(mddev->gendisk);
4679         } else {
4680                 int d;
4681                 for (d = conf->geo.raid_disks ;
4682                      d < conf->geo.raid_disks - mddev->delta_disks;
4683                      d++) {
4684                         struct md_rdev *rdev = conf->mirrors[d].rdev;
4685                         if (rdev)
4686                                 clear_bit(In_sync, &rdev->flags);
4687                         rdev = conf->mirrors[d].replacement;
4688                         if (rdev)
4689                                 clear_bit(In_sync, &rdev->flags);
4690                 }
4691         }
4692         mddev->layout = mddev->new_layout;
4693         mddev->chunk_sectors = 1 << conf->geo.chunk_shift;
4694         mddev->reshape_position = MaxSector;
4695         mddev->delta_disks = 0;
4696         mddev->reshape_backwards = 0;
4697 }
4698
4699 static struct md_personality raid10_personality =
4700 {
4701         .name           = "raid10",
4702         .level          = 10,
4703         .owner          = THIS_MODULE,
4704         .make_request   = make_request,
4705         .run            = run,
4706         .stop           = stop,
4707         .status         = status,
4708         .error_handler  = error,
4709         .hot_add_disk   = raid10_add_disk,
4710         .hot_remove_disk= raid10_remove_disk,
4711         .spare_active   = raid10_spare_active,
4712         .sync_request   = sync_request,
4713         .quiesce        = raid10_quiesce,
4714         .size           = raid10_size,
4715         .resize         = raid10_resize,
4716         .takeover       = raid10_takeover,
4717         .check_reshape  = raid10_check_reshape,
4718         .start_reshape  = raid10_start_reshape,
4719         .finish_reshape = raid10_finish_reshape,
4720 };
4721
4722 static int __init raid_init(void)
4723 {
4724         return register_md_personality(&raid10_personality);
4725 }
4726
4727 static void raid_exit(void)
4728 {
4729         unregister_md_personality(&raid10_personality);
4730 }
4731
4732 module_init(raid_init);
4733 module_exit(raid_exit);
4734 MODULE_LICENSE("GPL");
4735 MODULE_DESCRIPTION("RAID10 (striped mirror) personality for MD");
4736 MODULE_ALIAS("md-personality-9"); /* RAID10 */
4737 MODULE_ALIAS("md-raid10");
4738 MODULE_ALIAS("md-level-10");
4739
4740 module_param(max_queued_requests, int, S_IRUGO|S_IWUSR);