drivers/md/raid5.c

   1 /*
   2  * raid5.c : Multiple Devices driver for Linux
   3  *         Copyright (C) 1996, 1997 Ingo Molnar, Miguel de Icaza, Gadi Oxman
   4  *         Copyright (C) 1999, 2000 Ingo Molnar
   5  *         Copyright (C) 2002, 2003 H. Peter Anvin
   6  *
   7  * RAID-4/5/6 management functions.
   8  * Thanks to Penguin Computing for making the RAID-6 development possible
   9  * by donating a test server!
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2, or (at your option)
  14  * any later version.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * (for example /usr/src/linux/COPYING); if not, write to the Free
  18  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  */
  20
  21 /*
  22  * BITMAP UNPLUGGING:
  23  *
  24  * The sequencing for updating the bitmap reliably is a little
  25  * subtle (and I got it wrong the first time) so it deserves some
  26  * explanation.
  27  *
  28  * We group bitmap updates into batches.  Each batch has a number.
  29  * We may write out several batches at once, but that isn't very important.
  30  * conf->seq_write is the number of the last batch successfully written.
  31  * conf->seq_flush is the number of the last batch that was closed to
  32  *    new additions.
  33  * When we discover that we will need to write to any block in a stripe
  34  * (in add_stripe_bio) we update the in-memory bitmap and record in sh->bm_seq
  35  * the number of the batch it will be in. This is seq_flush+1.
  36  * When we are ready to do a write, if that batch hasn't been written yet,
  37  *   we plug the array and queue the stripe for later.
  38  * When an unplug happens, we increment bm_flush, thus closing the current
  39  *   batch.
  40  * When we notice that bm_flush > bm_write, we write out all pending updates
  41  * to the bitmap, and advance bm_write to where bm_flush was.
  42  * This may occasionally write a bit out twice, but is sure never to
  43  * miss any bits.
  44  */
  45
  46 #include <linux/blkdev.h>
  47 #include <linux/kthread.h>
  48 #include <linux/raid/pq.h>
  49 #include <linux/async_tx.h>
  50 #include <linux/module.h>
  51 #include <linux/async.h>
  52 #include <linux/seq_file.h>
  53 #include <linux/cpu.h>
  54 #include <linux/slab.h>
  55 #include <linux/ratelimit.h>
  56 #include <trace/events/block.h>
  57
  58 #include "md.h"
  59 #include "raid5.h"
  60 #include "raid0.h"
  61 #include "bitmap.h"
  62
  63 /*
  64  * Stripe cache
  65  */
  66
  67 #define NR_STRIPES              256
  68 #define STRIPE_SIZE             PAGE_SIZE
  69 #define STRIPE_SHIFT            (PAGE_SHIFT - 9)
  70 #define STRIPE_SECTORS          (STRIPE_SIZE>>9)
  71 #define IO_THRESHOLD            1
  72 #define BYPASS_THRESHOLD        1
  73 #define NR_HASH                 (PAGE_SIZE / sizeof(struct hlist_head))
  74 #define HASH_MASK               (NR_HASH - 1)
  75
  76 static inline struct hlist_head *stripe_hash(struct r5conf *conf, sector_t sect)
  77 {
  78         int hash = (sect >> STRIPE_SHIFT) & HASH_MASK;
  79         return &conf->stripe_hashtbl[hash];
  80 }
  81
  82 /* bio's attached to a stripe+device for I/O are linked together in bi_sector
  83  * order without overlap.  There may be several bio's per stripe+device, and
  84  * a bio could span several devices.
  85  * When walking this list for a particular stripe+device, we must never proceed
  86  * beyond a bio that extends past this device, as the next bio might no longer
  87  * be valid.
  88  * This function is used to determine the 'next' bio in the list, given the sector
  89  * of the current stripe+device
  90  */
  91 static inline struct bio *r5_next_bio(struct bio *bio, sector_t sector)
  92 {
  93         int sectors = bio_sectors(bio);
  94         if (bio->bi_sector + sectors < sector + STRIPE_SECTORS)
  95                 return bio->bi_next;
  96         else
  97                 return NULL;
  98 }
  99
 100 /*
 101  * We maintain a biased count of active stripes in the bottom 16 bits of
 102  * bi_phys_segments, and a count of processed stripes in the upper 16 bits
 103  */
 104 static inline int raid5_bi_processed_stripes(struct bio *bio)
 105 {
 106         atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 107         return (atomic_read(segments) >> 16) & 0xffff;
 108 }
 109
 110 static inline int raid5_dec_bi_active_stripes(struct bio *bio)
 111 {
 112         atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 113         return atomic_sub_return(1, segments) & 0xffff;
 114 }
 115
 116 static inline void raid5_inc_bi_active_stripes(struct bio *bio)
 117 {
 118         atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 119         atomic_inc(segments);
 120 }
 121
 122 static inline void raid5_set_bi_processed_stripes(struct bio *bio,
 123         unsigned int cnt)
 124 {
 125         atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 126         int old, new;
 127
 128         do {
 129                 old = atomic_read(segments);
 130                 new = (old & 0xffff) | (cnt << 16);
 131         } while (atomic_cmpxchg(segments, old, new) != old);
 132 }
 133
 134 static inline void raid5_set_bi_stripes(struct bio *bio, unsigned int cnt)
 135 {
 136         atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 137         atomic_set(segments, cnt);
 138 }
 139
 140 /* Find first data disk in a raid6 stripe */
 141 static inline int raid6_d0(struct stripe_head *sh)
 142 {
 143         if (sh->ddf_layout)
 144                 /* ddf always start from first device */
 145                 return 0;
 146         /* md starts just after Q block */
 147         if (sh->qd_idx == sh->disks - 1)
 148                 return 0;
 149         else
 150                 return sh->qd_idx + 1;
 151 }
 152 static inline int raid6_next_disk(int disk, int raid_disks)
 153 {
 154         disk++;
 155         return (disk < raid_disks) ? disk : 0;
 156 }
 157
 158 /* When walking through the disks in a raid5, starting at raid6_d0,
 159  * We need to map each disk to a 'slot', where the data disks are slot
 160  * 0 .. raid_disks-3, the parity disk is raid_disks-2 and the Q disk
 161  * is raid_disks-1.  This help does that mapping.
 162  */
 163 static int raid6_idx_to_slot(int idx, struct stripe_head *sh,
 164                              int *count, int syndrome_disks)
 165 {
 166         int slot = *count;
 167
 168         if (sh->ddf_layout)
 169                 (*count)++;
 170         if (idx == sh->pd_idx)
 171                 return syndrome_disks;
 172         if (idx == sh->qd_idx)
 173                 return syndrome_disks + 1;
 174         if (!sh->ddf_layout)
 175                 (*count)++;
 176         return slot;
 177 }
 178
 179 static void return_io(struct bio *return_bi)
 180 {
 181         struct bio *bi = return_bi;
 182         while (bi) {
 183
 184                 return_bi = bi->bi_next;
 185                 bi->bi_next = NULL;
 186                 bi->bi_size = 0;
 187                 trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
 188                                          bi, 0);
 189                 bio_endio(bi, 0);
 190                 bi = return_bi;
 191         }
 192 }
 193
 194 static void print_raid5_conf (struct r5conf *conf);
 195
 196 static int stripe_operations_active(struct stripe_head *sh)
 197 {
 198         return sh->check_state || sh->reconstruct_state ||
 199                test_bit(STRIPE_BIOFILL_RUN, &sh->state) ||
 200                test_bit(STRIPE_COMPUTE_RUN, &sh->state);
 201 }
 202
 203 static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh)
 204 {
 205         BUG_ON(!list_empty(&sh->lru));
 206         BUG_ON(atomic_read(&conf->active_stripes)==0);
 207         if (test_bit(STRIPE_HANDLE, &sh->state)) {
 208                 if (test_bit(STRIPE_DELAYED, &sh->state) &&
 209                     !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 210                         list_add_tail(&sh->lru, &conf->delayed_list);
 211                 else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
 212                            sh->bm_seq - conf->seq_write > 0)
 213                         list_add_tail(&sh->lru, &conf->bitmap_list);
 214                 else {
 215                         clear_bit(STRIPE_DELAYED, &sh->state);
 216                         clear_bit(STRIPE_BIT_DELAY, &sh->state);
 217                         list_add_tail(&sh->lru, &conf->handle_list);
 218                 }
 219                 md_wakeup_thread(conf->mddev->thread);
 220         } else {
 221                 BUG_ON(stripe_operations_active(sh));
 222                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 223                         if (atomic_dec_return(&conf->preread_active_stripes)
 224                             < IO_THRESHOLD)
 225                                 md_wakeup_thread(conf->mddev->thread);
 226                 atomic_dec(&conf->active_stripes);
 227                 if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
 228                         list_add_tail(&sh->lru, &conf->inactive_list);
 229                         wake_up(&conf->wait_for_stripe);
 230                         if (conf->retry_read_aligned)
 231                                 md_wakeup_thread(conf->mddev->thread);
 232                 }
 233         }
 234 }
 235
 236 static void __release_stripe(struct r5conf *conf, struct stripe_head *sh)
 237 {
 238         if (atomic_dec_and_test(&sh->count))
 239                 do_release_stripe(conf, sh);
 240 }
 241
 242 static void release_stripe(struct stripe_head *sh)
 243 {
 244         struct r5conf *conf = sh->raid_conf;
 245         unsigned long flags;
 246
 247         local_irq_save(flags);
 248         if (atomic_dec_and_lock(&sh->count, &conf->device_lock)) {
 249                 do_release_stripe(conf, sh);
 250                 spin_unlock(&conf->device_lock);
 251         }
 252         local_irq_restore(flags);
 253 }
 254
 255 static inline void remove_hash(struct stripe_head *sh)
 256 {
 257         pr_debug("remove_hash(), stripe %llu\n",
 258                 (unsigned long long)sh->sector);
 259
 260         hlist_del_init(&sh->hash);
 261 }
 262
 263 static inline void insert_hash(struct r5conf *conf, struct stripe_head *sh)
 264 {
 265         struct hlist_head *hp = stripe_hash(conf, sh->sector);
 266
 267         pr_debug("insert_hash(), stripe %llu\n",
 268                 (unsigned long long)sh->sector);
 269
 270         hlist_add_head(&sh->hash, hp);
 271 }
 272
 273
 274 /* find an idle stripe, make sure it is unhashed, and return it. */
 275 static struct stripe_head *get_free_stripe(struct r5conf *conf)
 276 {
 277         struct stripe_head *sh = NULL;
 278         struct list_head *first;
 279
 280         if (list_empty(&conf->inactive_list))
 281                 goto out;
 282         first = conf->inactive_list.next;
 283         sh = list_entry(first, struct stripe_head, lru);
 284         list_del_init(first);
 285         remove_hash(sh);
 286         atomic_inc(&conf->active_stripes);
 287 out:
 288         return sh;
 289 }
 290
 291 static void shrink_buffers(struct stripe_head *sh)
 292 {
 293         struct page *p;
 294         int i;
 295         int num = sh->raid_conf->pool_size;
 296
 297         for (i = 0; i < num ; i++) {
 298                 p = sh->dev[i].page;
 299                 if (!p)
 300                         continue;
 301                 sh->dev[i].page = NULL;
 302                 put_page(p);
 303         }
 304 }
 305
 306 static int grow_buffers(struct stripe_head *sh)
 307 {
 308         int i;
 309         int num = sh->raid_conf->pool_size;
 310
 311         for (i = 0; i < num; i++) {
 312                 struct page *page;
 313
 314                 if (!(page = alloc_page(GFP_KERNEL))) {
 315                         return 1;
 316                 }
 317                 sh->dev[i].page = page;
 318         }
 319         return 0;
 320 }
 321
 322 static void raid5_build_block(struct stripe_head *sh, int i, int previous);
 323 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
 324                             struct stripe_head *sh);
 325
 326 static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
 327 {
 328         struct r5conf *conf = sh->raid_conf;
 329         int i;
 330
 331         BUG_ON(atomic_read(&sh->count) != 0);
 332         BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
 333         BUG_ON(stripe_operations_active(sh));
 334
 335         pr_debug("init_stripe called, stripe %llu\n",
 336                 (unsigned long long)sh->sector);
 337
 338         remove_hash(sh);
 339
 340         sh->generation = conf->generation - previous;
 341         sh->disks = previous ? conf->previous_raid_disks : conf->raid_disks;
 342         sh->sector = sector;
 343         stripe_set_idx(sector, conf, previous, sh);
 344         sh->state = 0;
 345
 346
 347         for (i = sh->disks; i--; ) {
 348                 struct r5dev *dev = &sh->dev[i];
 349
 350                 if (dev->toread || dev->read || dev->towrite || dev->written ||
 351                     test_bit(R5_LOCKED, &dev->flags)) {
 352                         printk(KERN_ERR "sector=%llx i=%d %p %p %p %p %d\n",
 353                                (unsigned long long)sh->sector, i, dev->toread,
 354                                dev->read, dev->towrite, dev->written,
 355                                test_bit(R5_LOCKED, &dev->flags));
 356                         WARN_ON(1);
 357                 }
 358                 dev->flags = 0;
 359                 raid5_build_block(sh, i, previous);
 360         }
 361         insert_hash(conf, sh);
 362 }
 363
 364 static struct stripe_head *__find_stripe(struct r5conf *conf, sector_t sector,
 365                                          short generation)
 366 {
 367         struct stripe_head *sh;
 368
 369         pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
 370         hlist_for_each_entry(sh, stripe_hash(conf, sector), hash)
 371                 if (sh->sector == sector && sh->generation == generation)
 372                         return sh;
 373         pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
 374         return NULL;
 375 }
 376
 377 /*
 378  * Need to check if array has failed when deciding whether to:
 379  *  - start an array
 380  *  - remove non-faulty devices
 381  *  - add a spare
 382  *  - allow a reshape
 383  * This determination is simple when no reshape is happening.
 384  * However if there is a reshape, we need to carefully check
 385  * both the before and after sections.
 386  * This is because some failed devices may only affect one
 387  * of the two sections, and some non-in_sync devices may
 388  * be insync in the section most affected by failed devices.
 389  */
 390 static int calc_degraded(struct r5conf *conf)
 391 {
 392         int degraded, degraded2;
 393         int i;
 394
 395         rcu_read_lock();
 396         degraded = 0;
 397         for (i = 0; i < conf->previous_raid_disks; i++) {
 398                 struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
 399                 if (rdev && test_bit(Faulty, &rdev->flags))
 400                         rdev = rcu_dereference(conf->disks[i].replacement);
 401                 if (!rdev || test_bit(Faulty, &rdev->flags))
 402                         degraded++;
 403                 else if (test_bit(In_sync, &rdev->flags))
 404                         ;
 405                 else
 406                         /* not in-sync or faulty.
 407                          * If the reshape increases the number of devices,
 408                          * this is being recovered by the reshape, so
 409                          * this 'previous' section is not in_sync.
 410                          * If the number of devices is being reduced however,
 411                          * the device can only be part of the array if
 412                          * we are reverting a reshape, so this section will
 413                          * be in-sync.
 414                          */
 415                         if (conf->raid_disks >= conf->previous_raid_disks)
 416                                 degraded++;
 417         }
 418         rcu_read_unlock();
 419         if (conf->raid_disks == conf->previous_raid_disks)
 420                 return degraded;
 421         rcu_read_lock();
 422         degraded2 = 0;
 423         for (i = 0; i < conf->raid_disks; i++) {
 424                 struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
 425                 if (rdev && test_bit(Faulty, &rdev->flags))
 426                         rdev = rcu_dereference(conf->disks[i].replacement);
 427                 if (!rdev || test_bit(Faulty, &rdev->flags))
 428                         degraded2++;
 429                 else if (test_bit(In_sync, &rdev->flags))
 430                         ;
 431                 else
 432                         /* not in-sync or faulty.
 433                          * If reshape increases the number of devices, this
 434                          * section has already been recovered, else it
 435                          * almost certainly hasn't.
 436                          */
 437                         if (conf->raid_disks <= conf->previous_raid_disks)
 438                                 degraded2++;
 439         }
 440         rcu_read_unlock();
 441         if (degraded2 > degraded)
 442                 return degraded2;
 443         return degraded;
 444 }
 445
 446 static int has_failed(struct r5conf *conf)
 447 {
 448         int degraded;
 449
 450         if (conf->mddev->reshape_position == MaxSector)
 451                 return conf->mddev->degraded > conf->max_degraded;
 452
 453         degraded = calc_degraded(conf);
 454         if (degraded > conf->max_degraded)
 455                 return 1;
 456         return 0;
 457 }
 458
 459 static struct stripe_head *
 460 get_active_stripe(struct r5conf *conf, sector_t sector,
 461                   int previous, int noblock, int noquiesce)
 462 {
 463         struct stripe_head *sh;
 464
 465         pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
 466
 467         spin_lock_irq(&conf->device_lock);
 468
 469         do {
 470                 wait_event_lock_irq(conf->wait_for_stripe,
 471                                     conf->quiesce == 0 || noquiesce,
 472                                     conf->device_lock);
 473                 sh = __find_stripe(conf, sector, conf->generation - previous);
 474                 if (!sh) {
 475                         if (!conf->inactive_blocked)
 476                                 sh = get_free_stripe(conf);
 477                         if (noblock && sh == NULL)
 478                                 break;
 479                         if (!sh) {
 480                                 conf->inactive_blocked = 1;
 481                                 wait_event_lock_irq(conf->wait_for_stripe,
 482                                                     !list_empty(&conf->inactive_list) &&
 483                                                     (atomic_read(&conf->active_stripes)
 484                                                      < (conf->max_nr_stripes *3/4)
 485                                                      || !conf->inactive_blocked),
 486                                                     conf->device_lock);
 487                                 conf->inactive_blocked = 0;
 488                         } else
 489                                 init_stripe(sh, sector, previous);
 490                 } else {
 491                         if (atomic_read(&sh->count)) {
 492                                 BUG_ON(!list_empty(&sh->lru)
 493                                     && !test_bit(STRIPE_EXPANDING, &sh->state)
 494                                     && !test_bit(STRIPE_ON_UNPLUG_LIST, &sh->state));
 495                         } else {
 496                                 if (!test_bit(STRIPE_HANDLE, &sh->state))
 497                                         atomic_inc(&conf->active_stripes);
 498                                 if (list_empty(&sh->lru) &&
 499                                     !test_bit(STRIPE_EXPANDING, &sh->state))
 500                                         BUG();
 501                                 list_del_init(&sh->lru);
 502                         }
 503                 }
 504         } while (sh == NULL);
 505
 506         if (sh)
 507                 atomic_inc(&sh->count);
 508
 509         spin_unlock_irq(&conf->device_lock);
 510         return sh;
 511 }
 512
 513 /* Determine if 'data_offset' or 'new_data_offset' should be used
 514  * in this stripe_head.
 515  */
 516 static int use_new_offset(struct r5conf *conf, struct stripe_head *sh)
 517 {
 518         sector_t progress = conf->reshape_progress;
 519         /* Need a memory barrier to make sure we see the value
 520          * of conf->generation, or ->data_offset that was set before
 521          * reshape_progress was updated.
 522          */
 523         smp_rmb();
 524         if (progress == MaxSector)
 525                 return 0;
 526         if (sh->generation == conf->generation - 1)
 527                 return 0;
 528         /* We are in a reshape, and this is a new-generation stripe,
 529          * so use new_data_offset.
 530          */
 531         return 1;
 532 }
 533
 534 static void
 535 raid5_end_read_request(struct bio *bi, int error);
 536 static void
 537 raid5_end_write_request(struct bio *bi, int error);
 538
 539 static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
 540 {
 541         struct r5conf *conf = sh->raid_conf;
 542         int i, disks = sh->disks;
 543
 544         might_sleep();
 545
 546         for (i = disks; i--; ) {
 547                 int rw;
 548                 int replace_only = 0;
 549                 struct bio *bi, *rbi;
 550                 struct md_rdev *rdev, *rrdev = NULL;
 551                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
 552                         if (test_and_clear_bit(R5_WantFUA, &sh->dev[i].flags))
 553                                 rw = WRITE_FUA;
 554                         else
 555                                 rw = WRITE;
 556                         if (test_bit(R5_Discard, &sh->dev[i].flags))
 557                                 rw |= REQ_DISCARD;
 558                 } else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
 559                         rw = READ;
 560                 else if (test_and_clear_bit(R5_WantReplace,
 561                                             &sh->dev[i].flags)) {
 562                         rw = WRITE;
 563                         replace_only = 1;
 564                 } else
 565                         continue;
 566                 if (test_and_clear_bit(R5_SyncIO, &sh->dev[i].flags))
 567                         rw |= REQ_SYNC;
 568
 569                 bi = &sh->dev[i].req;
 570                 rbi = &sh->dev[i].rreq; /* For writing to replacement */
 571
 572                 rcu_read_lock();
 573                 rrdev = rcu_dereference(conf->disks[i].replacement);
 574                 smp_mb(); /* Ensure that if rrdev is NULL, rdev won't be */
 575                 rdev = rcu_dereference(conf->disks[i].rdev);
 576                 if (!rdev) {
 577                         rdev = rrdev;
 578                         rrdev = NULL;
 579                 }
 580                 if (rw & WRITE) {
 581                         if (replace_only)
 582                                 rdev = NULL;
 583                         if (rdev == rrdev)
 584                                 /* We raced and saw duplicates */
 585                                 rrdev = NULL;
 586                 } else {
 587                         if (test_bit(R5_ReadRepl, &sh->dev[i].flags) && rrdev)
 588                                 rdev = rrdev;
 589                         rrdev = NULL;
 590                 }
 591
 592                 if (rdev && test_bit(Faulty, &rdev->flags))
 593                         rdev = NULL;
 594                 if (rdev)
 595                         atomic_inc(&rdev->nr_pending);
 596                 if (rrdev && test_bit(Faulty, &rrdev->flags))
 597                         rrdev = NULL;
 598                 if (rrdev)
 599                         atomic_inc(&rrdev->nr_pending);
 600                 rcu_read_unlock();
 601
 602                 /* We have already checked bad blocks for reads.  Now
 603                  * need to check for writes.  We never accept write errors
 604                  * on the replacement, so we don't to check rrdev.
 605                  */
 606                 while ((rw & WRITE) && rdev &&
 607                        test_bit(WriteErrorSeen, &rdev->flags)) {
 608                         sector_t first_bad;
 609                         int bad_sectors;
 610                         int bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
 611                                               &first_bad, &bad_sectors);
 612                         if (!bad)
 613                                 break;
 614
 615                         if (bad < 0) {
 616                                 set_bit(BlockedBadBlocks, &rdev->flags);
 617                                 if (!conf->mddev->external &&
 618                                     conf->mddev->flags) {
 619                                         /* It is very unlikely, but we might
 620                                          * still need to write out the
 621                                          * bad block log - better give it
 622                                          * a chance*/
 623                                         md_check_recovery(conf->mddev);
 624                                 }
 625                                 /*
 626                                  * Because md_wait_for_blocked_rdev
 627                                  * will dec nr_pending, we must
 628                                  * increment it first.
 629                                  */
 630                                 atomic_inc(&rdev->nr_pending);
 631                                 md_wait_for_blocked_rdev(rdev, conf->mddev);
 632                         } else {
 633                                 /* Acknowledged bad block - skip the write */
 634                                 rdev_dec_pending(rdev, conf->mddev);
 635                                 rdev = NULL;
 636                         }
 637                 }
 638
 639                 if (rdev) {
 640                         if (s->syncing || s->expanding || s->expanded
 641                             || s->replacing)
 642                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
 643
 644                         set_bit(STRIPE_IO_STARTED, &sh->state);
 645
 646                         bio_reset(bi);
 647                         bi->bi_bdev = rdev->bdev;
 648                         bi->bi_rw = rw;
 649                         bi->bi_end_io = (rw & WRITE)
 650                                 ? raid5_end_write_request
 651                                 : raid5_end_read_request;
 652                         bi->bi_private = sh;
 653
 654                         pr_debug("%s: for %llu schedule op %ld on disc %d\n",
 655                                 __func__, (unsigned long long)sh->sector,
 656                                 bi->bi_rw, i);
 657                         atomic_inc(&sh->count);
 658                         if (use_new_offset(conf, sh))
 659                                 bi->bi_sector = (sh->sector
 660                                                  + rdev->new_data_offset);
 661                         else
 662                                 bi->bi_sector = (sh->sector
 663                                                  + rdev->data_offset);
 664                         if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
 665                                 bi->bi_rw |= REQ_FLUSH;
 666
 667                         bi->bi_vcnt = 1;
 668                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
 669                         bi->bi_io_vec[0].bv_offset = 0;
 670                         bi->bi_size = STRIPE_SIZE;
 671                         /*
 672                          * If this is discard request, set bi_vcnt 0. We don't
 673                          * want to confuse SCSI because SCSI will replace payload
 674                          */
 675                         if (rw & REQ_DISCARD)
 676                                 bi->bi_vcnt = 0;
 677                         if (rrdev)
 678                                 set_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags);
 679
 680                         if (conf->mddev->gendisk)
 681                                 trace_block_bio_remap(bdev_get_queue(bi->bi_bdev),
 682                                                       bi, disk_devt(conf->mddev->gendisk),
 683                                                       sh->dev[i].sector);
 684                         generic_make_request(bi);
 685                 }
 686                 if (rrdev) {
 687                         if (s->syncing || s->expanding || s->expanded
 688                             || s->replacing)
 689                                 md_sync_acct(rrdev->bdev, STRIPE_SECTORS);
 690
 691                         set_bit(STRIPE_IO_STARTED, &sh->state);
 692
 693                         bio_reset(rbi);
 694                         rbi->bi_bdev = rrdev->bdev;
 695                         rbi->bi_rw = rw;
 696                         BUG_ON(!(rw & WRITE));
 697                         rbi->bi_end_io = raid5_end_write_request;
 698                         rbi->bi_private = sh;
 699
 700                         pr_debug("%s: for %llu schedule op %ld on "
 701                                  "replacement disc %d\n",
 702                                 __func__, (unsigned long long)sh->sector,
 703                                 rbi->bi_rw, i);
 704                         atomic_inc(&sh->count);
 705                         if (use_new_offset(conf, sh))
 706                                 rbi->bi_sector = (sh->sector
 707                                                   + rrdev->new_data_offset);
 708                         else
 709                                 rbi->bi_sector = (sh->sector
 710                                                   + rrdev->data_offset);
 711                         rbi->bi_vcnt = 1;
 712                         rbi->bi_io_vec[0].bv_len = STRIPE_SIZE;
 713                         rbi->bi_io_vec[0].bv_offset = 0;
 714                         rbi->bi_size = STRIPE_SIZE;
 715                         /*
 716                          * If this is discard request, set bi_vcnt 0. We don't
 717                          * want to confuse SCSI because SCSI will replace payload
 718                          */
 719                         if (rw & REQ_DISCARD)
 720                                 rbi->bi_vcnt = 0;
 721                         if (conf->mddev->gendisk)
 722                                 trace_block_bio_remap(bdev_get_queue(rbi->bi_bdev),
 723                                                       rbi, disk_devt(conf->mddev->gendisk),
 724                                                       sh->dev[i].sector);
 725                         generic_make_request(rbi);
 726                 }
 727                 if (!rdev && !rrdev) {
 728                         if (rw & WRITE)
 729                                 set_bit(STRIPE_DEGRADED, &sh->state);
 730                         pr_debug("skip op %ld on disc %d for sector %llu\n",
 731                                 bi->bi_rw, i, (unsigned long long)sh->sector);
 732                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
 733                         set_bit(STRIPE_HANDLE, &sh->state);
 734                 }
 735         }
 736 }
 737
 738 static struct dma_async_tx_descriptor *
 739 async_copy_data(int frombio, struct bio *bio, struct page *page,
 740         sector_t sector, struct dma_async_tx_descriptor *tx)
 741 {
 742         struct bio_vec *bvl;
 743         struct page *bio_page;
 744         int i;
 745         int page_offset;
 746         struct async_submit_ctl submit;
 747         enum async_tx_flags flags = 0;
 748
 749         if (bio->bi_sector >= sector)
 750                 page_offset = (signed)(bio->bi_sector - sector) * 512;
 751         else
 752                 page_offset = (signed)(sector - bio->bi_sector) * -512;
 753
 754         if (frombio)
 755                 flags |= ASYNC_TX_FENCE;
 756         init_async_submit(&submit, flags, tx, NULL, NULL, NULL);
 757
 758         bio_for_each_segment(bvl, bio, i) {
 759                 int len = bvl->bv_len;
 760                 int clen;
 761                 int b_offset = 0;
 762
 763                 if (page_offset < 0) {
 764                         b_offset = -page_offset;
 765                         page_offset += b_offset;
 766                         len -= b_offset;
 767                 }
 768
 769                 if (len > 0 && page_offset + len > STRIPE_SIZE)
 770                         clen = STRIPE_SIZE - page_offset;
 771                 else
 772                         clen = len;
 773
 774                 if (clen > 0) {
 775                         b_offset += bvl->bv_offset;
 776                         bio_page = bvl->bv_page;
 777                         if (frombio)
 778                                 tx = async_memcpy(page, bio_page, page_offset,
 779                                                   b_offset, clen, &submit);
 780                         else
 781                                 tx = async_memcpy(bio_page, page, b_offset,
 782                                                   page_offset, clen, &submit);
 783                 }
 784                 /* chain the operations */
 785                 submit.depend_tx = tx;
 786
 787                 if (clen < len) /* hit end of page */
 788                         break;
 789                 page_offset +=  len;
 790         }
 791
 792         return tx;
 793 }
 794
 795 static void ops_complete_biofill(void *stripe_head_ref)
 796 {
 797         struct stripe_head *sh = stripe_head_ref;
 798         struct bio *return_bi = NULL;
 799         int i;
 800
 801         pr_debug("%s: stripe %llu\n", __func__,
 802                 (unsigned long long)sh->sector);
 803
 804         /* clear completed biofills */
 805         for (i = sh->disks; i--; ) {
 806                 struct r5dev *dev = &sh->dev[i];
 807
 808                 /* acknowledge completion of a biofill operation */
 809                 /* and check if we need to reply to a read request,
 810                  * new R5_Wantfill requests are held off until
 811                  * !STRIPE_BIOFILL_RUN
 812                  */
 813                 if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
 814                         struct bio *rbi, *rbi2;
 815
 816                         BUG_ON(!dev->read);
 817                         rbi = dev->read;
 818                         dev->read = NULL;
 819                         while (rbi && rbi->bi_sector <
 820                                 dev->sector + STRIPE_SECTORS) {
 821                                 rbi2 = r5_next_bio(rbi, dev->sector);
 822                                 if (!raid5_dec_bi_active_stripes(rbi)) {
 823                                         rbi->bi_next = return_bi;
 824                                         return_bi = rbi;
 825                                 }
 826                                 rbi = rbi2;
 827                         }
 828                 }
 829         }
 830         clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
 831
 832         return_io(return_bi);
 833
 834         set_bit(STRIPE_HANDLE, &sh->state);
 835         release_stripe(sh);
 836 }
 837
 838 static void ops_run_biofill(struct stripe_head *sh)
 839 {
 840         struct dma_async_tx_descriptor *tx = NULL;
 841         struct async_submit_ctl submit;
 842         int i;
 843
 844         pr_debug("%s: stripe %llu\n", __func__,
 845                 (unsigned long long)sh->sector);
 846
 847         for (i = sh->disks; i--; ) {
 848                 struct r5dev *dev = &sh->dev[i];
 849                 if (test_bit(R5_Wantfill, &dev->flags)) {
 850                         struct bio *rbi;
 851                         spin_lock_irq(&sh->stripe_lock);
 852                         dev->read = rbi = dev->toread;
 853                         dev->toread = NULL;
 854                         spin_unlock_irq(&sh->stripe_lock);
 855                         while (rbi && rbi->bi_sector <
 856                                 dev->sector + STRIPE_SECTORS) {
 857                                 tx = async_copy_data(0, rbi, dev->page,
 858                                         dev->sector, tx);
 859                                 rbi = r5_next_bio(rbi, dev->sector);
 860                         }
 861                 }
 862         }
 863
 864         atomic_inc(&sh->count);
 865         init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_biofill, sh, NULL);
 866         async_trigger_callback(&submit);
 867 }
 868
 869 static void mark_target_uptodate(struct stripe_head *sh, int target)
 870 {
 871         struct r5dev *tgt;
 872
 873         if (target < 0)
 874                 return;
 875
 876         tgt = &sh->dev[target];
 877         set_bit(R5_UPTODATE, &tgt->flags);
 878         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
 879         clear_bit(R5_Wantcompute, &tgt->flags);
 880 }
 881
 882 static void ops_complete_compute(void *stripe_head_ref)
 883 {
 884         struct stripe_head *sh = stripe_head_ref;
 885
 886         pr_debug("%s: stripe %llu\n", __func__,
 887                 (unsigned long long)sh->sector);
 888
 889         /* mark the computed target(s) as uptodate */
 890         mark_target_uptodate(sh, sh->ops.target);
 891         mark_target_uptodate(sh, sh->ops.target2);
 892
 893         clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
 894         if (sh->check_state == check_state_compute_run)
 895                 sh->check_state = check_state_compute_result;
 896         set_bit(STRIPE_HANDLE, &sh->state);
 897         release_stripe(sh);
 898 }
 899
 900 /* return a pointer to the address conversion region of the scribble buffer */
 901 static addr_conv_t *to_addr_conv(struct stripe_head *sh,
 902                                  struct raid5_percpu *percpu)
 903 {
 904         return percpu->scribble + sizeof(struct page *) * (sh->disks + 2);
 905 }
 906
 907 static struct dma_async_tx_descriptor *
 908 ops_run_compute5(struct stripe_head *sh, struct raid5_percpu *percpu)
 909 {
 910         int disks = sh->disks;
 911         struct page **xor_srcs = percpu->scribble;
 912         int target = sh->ops.target;
 913         struct r5dev *tgt = &sh->dev[target];
 914         struct page *xor_dest = tgt->page;
 915         int count = 0;
 916         struct dma_async_tx_descriptor *tx;
 917         struct async_submit_ctl submit;
 918         int i;
 919
 920         pr_debug("%s: stripe %llu block: %d\n",
 921                 __func__, (unsigned long long)sh->sector, target);
 922         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
 923
 924         for (i = disks; i--; )
 925                 if (i != target)
 926                         xor_srcs[count++] = sh->dev[i].page;
 927
 928         atomic_inc(&sh->count);
 929
 930         init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, NULL,
 931                           ops_complete_compute, sh, to_addr_conv(sh, percpu));
 932         if (unlikely(count == 1))
 933                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
 934         else
 935                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
 936
 937         return tx;
 938 }
 939
 940 /* set_syndrome_sources - populate source buffers for gen_syndrome
 941  * @srcs - (struct page *) array of size sh->disks
 942  * @sh - stripe_head to parse
 943  *
 944  * Populates srcs in proper layout order for the stripe and returns the
 945  * 'count' of sources to be used in a call to async_gen_syndrome.  The P
 946  * destination buffer is recorded in srcs[count] and the Q destination
 947  * is recorded in srcs[count+1]].
 948  */
 949 static int set_syndrome_sources(struct page **srcs, struct stripe_head *sh)
 950 {
 951         int disks = sh->disks;
 952         int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
 953         int d0_idx = raid6_d0(sh);
 954         int count;
 955         int i;
 956
 957         for (i = 0; i < disks; i++)
 958                 srcs[i] = NULL;
 959
 960         count = 0;
 961         i = d0_idx;
 962         do {
 963                 int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
 964
 965                 srcs[slot] = sh->dev[i].page;
 966                 i = raid6_next_disk(i, disks);
 967         } while (i != d0_idx);
 968
 969         return syndrome_disks;
 970 }
 971
 972 static struct dma_async_tx_descriptor *
 973 ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
 974 {
 975         int disks = sh->disks;
 976         struct page **blocks = percpu->scribble;
 977         int target;
 978         int qd_idx = sh->qd_idx;
 979         struct dma_async_tx_descriptor *tx;
 980         struct async_submit_ctl submit;
 981         struct r5dev *tgt;
 982         struct page *dest;
 983         int i;
 984         int count;
 985
 986         if (sh->ops.target < 0)
 987                 target = sh->ops.target2;
 988         else if (sh->ops.target2 < 0)
 989                 target = sh->ops.target;
 990         else
 991                 /* we should only have one valid target */
 992                 BUG();
 993         BUG_ON(target < 0);
 994         pr_debug("%s: stripe %llu block: %d\n",
 995                 __func__, (unsigned long long)sh->sector, target);
 996
 997         tgt = &sh->dev[target];
 998         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
 999         dest = tgt->page;
1000
1001         atomic_inc(&sh->count);
1002
1003         if (target == qd_idx) {
1004                 count = set_syndrome_sources(blocks, sh);
1005                 blocks[count] = NULL; /* regenerating p is not necessary */
1006                 BUG_ON(blocks[count+1] != dest); /* q should already be set */
1007                 init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1008                                   ops_complete_compute, sh,
1009                                   to_addr_conv(sh, percpu));
1010                 tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE, &submit);
1011         } else {
1012                 /* Compute any data- or p-drive using XOR */
1013                 count = 0;
1014                 for (i = disks; i-- ; ) {
1015                         if (i == target || i == qd_idx)
1016                                 continue;
1017                         blocks[count++] = sh->dev[i].page;
1018                 }
1019
1020                 init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1021                                   NULL, ops_complete_compute, sh,
1022                                   to_addr_conv(sh, percpu));
1023                 tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE, &submit);
1024         }
1025
1026         return tx;
1027 }
1028
1029 static struct dma_async_tx_descriptor *
1030 ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
1031 {
1032         int i, count, disks = sh->disks;
1033         int syndrome_disks = sh->ddf_layout ? disks : disks-2;
1034         int d0_idx = raid6_d0(sh);
1035         int faila = -1, failb = -1;
1036         int target = sh->ops.target;
1037         int target2 = sh->ops.target2;
1038         struct r5dev *tgt = &sh->dev[target];
1039         struct r5dev *tgt2 = &sh->dev[target2];
1040         struct dma_async_tx_descriptor *tx;
1041         struct page **blocks = percpu->scribble;
1042         struct async_submit_ctl submit;
1043
1044         pr_debug("%s: stripe %llu block1: %d block2: %d\n",
1045                  __func__, (unsigned long long)sh->sector, target, target2);
1046         BUG_ON(target < 0 || target2 < 0);
1047         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1048         BUG_ON(!test_bit(R5_Wantcompute, &tgt2->flags));
1049
1050         /* we need to open-code set_syndrome_sources to handle the
1051          * slot number conversion for 'faila' and 'failb'
1052          */
1053         for (i = 0; i < disks ; i++)
1054                 blocks[i] = NULL;
1055         count = 0;
1056         i = d0_idx;
1057         do {
1058                 int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1059
1060                 blocks[slot] = sh->dev[i].page;
1061
1062                 if (i == target)
1063                         faila = slot;
1064                 if (i == target2)
1065                         failb = slot;
1066                 i = raid6_next_disk(i, disks);
1067         } while (i != d0_idx);
1068
1069         BUG_ON(faila == failb);
1070         if (failb < faila)
1071                 swap(faila, failb);
1072         pr_debug("%s: stripe: %llu faila: %d failb: %d\n",
1073                  __func__, (unsigned long long)sh->sector, faila, failb);
1074
1075         atomic_inc(&sh->count);
1076
1077         if (failb == syndrome_disks+1) {
1078                 /* Q disk is one of the missing disks */
1079                 if (faila == syndrome_disks) {
1080                         /* Missing P+Q, just recompute */
1081                         init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1082                                           ops_complete_compute, sh,
1083                                           to_addr_conv(sh, percpu));
1084                         return async_gen_syndrome(blocks, 0, syndrome_disks+2,
1085                                                   STRIPE_SIZE, &submit);
1086                 } else {
1087                         struct page *dest;
1088                         int data_target;
1089                         int qd_idx = sh->qd_idx;
1090
1091                         /* Missing D+Q: recompute D from P, then recompute Q */
1092                         if (target == qd_idx)
1093                                 data_target = target2;
1094                         else
1095                                 data_target = target;
1096
1097                         count = 0;
1098                         for (i = disks; i-- ; ) {
1099                                 if (i == data_target || i == qd_idx)
1100                                         continue;
1101                                 blocks[count++] = sh->dev[i].page;
1102                         }
1103                         dest = sh->dev[data_target].page;
1104                         init_async_submit(&submit,
1105                                           ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1106                                           NULL, NULL, NULL,
1107                                           to_addr_conv(sh, percpu));
1108                         tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE,
1109                                        &submit);
1110
1111                         count = set_syndrome_sources(blocks, sh);
1112                         init_async_submit(&submit, ASYNC_TX_FENCE, tx,
1113                                           ops_complete_compute, sh,
1114                                           to_addr_conv(sh, percpu));
1115                         return async_gen_syndrome(blocks, 0, count+2,
1116                                                   STRIPE_SIZE, &submit);
1117                 }
1118         } else {
1119                 init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1120                                   ops_complete_compute, sh,
1121                                   to_addr_conv(sh, percpu));
1122                 if (failb == syndrome_disks) {
1123                         /* We're missing D+P. */
1124                         return async_raid6_datap_recov(syndrome_disks+2,
1125                                                        STRIPE_SIZE, faila,
1126                                                        blocks, &submit);
1127                 } else {
1128                         /* We're missing D+D. */
1129                         return async_raid6_2data_recov(syndrome_disks+2,
1130                                                        STRIPE_SIZE, faila, failb,
1131                                                        blocks, &submit);
1132                 }
1133         }
1134 }
1135
1136
1137 static void ops_complete_prexor(void *stripe_head_ref)
1138 {
1139         struct stripe_head *sh = stripe_head_ref;
1140
1141         pr_debug("%s: stripe %llu\n", __func__,
1142                 (unsigned long long)sh->sector);
1143 }
1144
1145 static struct dma_async_tx_descriptor *
1146 ops_run_prexor(struct stripe_head *sh, struct raid5_percpu *percpu,
1147                struct dma_async_tx_descriptor *tx)
1148 {
1149         int disks = sh->disks;
1150         struct page **xor_srcs = percpu->scribble;
1151         int count = 0, pd_idx = sh->pd_idx, i;
1152         struct async_submit_ctl submit;
1153
1154         /* existing parity data subtracted */
1155         struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1156
1157         pr_debug("%s: stripe %llu\n", __func__,
1158                 (unsigned long long)sh->sector);
1159
1160         for (i = disks; i--; ) {
1161                 struct r5dev *dev = &sh->dev[i];
1162                 /* Only process blocks that are known to be uptodate */
1163                 if (test_bit(R5_Wantdrain, &dev->flags))
1164                         xor_srcs[count++] = dev->page;
1165         }
1166
1167         init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
1168                           ops_complete_prexor, sh, to_addr_conv(sh, percpu));
1169         tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1170
1171         return tx;
1172 }
1173
1174 static struct dma_async_tx_descriptor *
1175 ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
1176 {
1177         int disks = sh->disks;
1178         int i;
1179
1180         pr_debug("%s: stripe %llu\n", __func__,
1181                 (unsigned long long)sh->sector);
1182
1183         for (i = disks; i--; ) {
1184                 struct r5dev *dev = &sh->dev[i];
1185                 struct bio *chosen;
1186
1187                 if (test_and_clear_bit(R5_Wantdrain, &dev->flags)) {
1188                         struct bio *wbi;
1189
1190                         spin_lock_irq(&sh->stripe_lock);
1191                         chosen = dev->towrite;
1192                         dev->towrite = NULL;
1193                         BUG_ON(dev->written);
1194                         wbi = dev->written = chosen;
1195                         spin_unlock_irq(&sh->stripe_lock);
1196
1197                         while (wbi && wbi->bi_sector <
1198                                 dev->sector + STRIPE_SECTORS) {
1199                                 if (wbi->bi_rw & REQ_FUA)
1200                                         set_bit(R5_WantFUA, &dev->flags);
1201                                 if (wbi->bi_rw & REQ_SYNC)
1202                                         set_bit(R5_SyncIO, &dev->flags);
1203                                 if (wbi->bi_rw & REQ_DISCARD)
1204                                         set_bit(R5_Discard, &dev->flags);
1205                                 else
1206                                         tx = async_copy_data(1, wbi, dev->page,
1207                                                 dev->sector, tx);
1208                                 wbi = r5_next_bio(wbi, dev->sector);
1209                         }
1210                 }
1211         }
1212
1213         return tx;
1214 }
1215
1216 static void ops_complete_reconstruct(void *stripe_head_ref)
1217 {
1218         struct stripe_head *sh = stripe_head_ref;
1219         int disks = sh->disks;
1220         int pd_idx = sh->pd_idx;
1221         int qd_idx = sh->qd_idx;
1222         int i;
1223         bool fua = false, sync = false, discard = false;
1224
1225         pr_debug("%s: stripe %llu\n", __func__,
1226                 (unsigned long long)sh->sector);
1227
1228         for (i = disks; i--; ) {
1229                 fua |= test_bit(R5_WantFUA, &sh->dev[i].flags);
1230                 sync |= test_bit(R5_SyncIO, &sh->dev[i].flags);
1231                 discard |= test_bit(R5_Discard, &sh->dev[i].flags);
1232         }
1233
1234         for (i = disks; i--; ) {
1235                 struct r5dev *dev = &sh->dev[i];
1236
1237                 if (dev->written || i == pd_idx || i == qd_idx) {
1238                         if (!discard)
1239                                 set_bit(R5_UPTODATE, &dev->flags);
1240                         if (fua)
1241                                 set_bit(R5_WantFUA, &dev->flags);
1242                         if (sync)
1243                                 set_bit(R5_SyncIO, &dev->flags);
1244                 }
1245         }
1246
1247         if (sh->reconstruct_state == reconstruct_state_drain_run)
1248                 sh->reconstruct_state = reconstruct_state_drain_result;
1249         else if (sh->reconstruct_state == reconstruct_state_prexor_drain_run)
1250                 sh->reconstruct_state = reconstruct_state_prexor_drain_result;
1251         else {
1252                 BUG_ON(sh->reconstruct_state != reconstruct_state_run);
1253                 sh->reconstruct_state = reconstruct_state_result;
1254         }
1255
1256         set_bit(STRIPE_HANDLE, &sh->state);
1257         release_stripe(sh);
1258 }
1259
1260 static void
1261 ops_run_reconstruct5(struct stripe_head *sh, struct raid5_percpu *percpu,
1262                      struct dma_async_tx_descriptor *tx)
1263 {
1264         int disks = sh->disks;
1265         struct page **xor_srcs = percpu->scribble;
1266         struct async_submit_ctl submit;
1267         int count = 0, pd_idx = sh->pd_idx, i;
1268         struct page *xor_dest;
1269         int prexor = 0;
1270         unsigned long flags;
1271
1272         pr_debug("%s: stripe %llu\n", __func__,
1273                 (unsigned long long)sh->sector);
1274
1275         for (i = 0; i < sh->disks; i++) {
1276                 if (pd_idx == i)
1277                         continue;
1278                 if (!test_bit(R5_Discard, &sh->dev[i].flags))
1279                         break;
1280         }
1281         if (i >= sh->disks) {
1282                 atomic_inc(&sh->count);
1283                 set_bit(R5_Discard, &sh->dev[pd_idx].flags);
1284                 ops_complete_reconstruct(sh);
1285                 return;
1286         }
1287         /* check if prexor is active which means only process blocks
1288          * that are part of a read-modify-write (written)
1289          */
1290         if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1291                 prexor = 1;
1292                 xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1293                 for (i = disks; i--; ) {
1294                         struct r5dev *dev = &sh->dev[i];
1295                         if (dev->written)
1296                                 xor_srcs[count++] = dev->page;
1297                 }
1298         } else {
1299                 xor_dest = sh->dev[pd_idx].page;
1300                 for (i = disks; i--; ) {
1301                         struct r5dev *dev = &sh->dev[i];
1302                         if (i != pd_idx)
1303                                 xor_srcs[count++] = dev->page;
1304                 }
1305         }
1306
1307         /* 1/ if we prexor'd then the dest is reused as a source
1308          * 2/ if we did not prexor then we are redoing the parity
1309          * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
1310          * for the synchronous xor case
1311          */
1312         flags = ASYNC_TX_ACK |
1313                 (prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
1314
1315         atomic_inc(&sh->count);
1316
1317         init_async_submit(&submit, flags, tx, ops_complete_reconstruct, sh,
1318                           to_addr_conv(sh, percpu));
1319         if (unlikely(count == 1))
1320                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1321         else
1322                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1323 }
1324
1325 static void
1326 ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
1327                      struct dma_async_tx_descriptor *tx)
1328 {
1329         struct async_submit_ctl submit;
1330         struct page **blocks = percpu->scribble;
1331         int count, i;
1332
1333         pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
1334
1335         for (i = 0; i < sh->disks; i++) {
1336                 if (sh->pd_idx == i || sh->qd_idx == i)
1337                         continue;
1338                 if (!test_bit(R5_Discard, &sh->dev[i].flags))
1339                         break;
1340         }
1341         if (i >= sh->disks) {
1342                 atomic_inc(&sh->count);
1343                 set_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
1344                 set_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
1345                 ops_complete_reconstruct(sh);
1346                 return;
1347         }
1348
1349         count = set_syndrome_sources(blocks, sh);
1350
1351         atomic_inc(&sh->count);
1352
1353         init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_reconstruct,
1354                           sh, to_addr_conv(sh, percpu));
1355         async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1356 }
1357
1358 static void ops_complete_check(void *stripe_head_ref)
1359 {
1360         struct stripe_head *sh = stripe_head_ref;
1361
1362         pr_debug("%s: stripe %llu\n", __func__,
1363                 (unsigned long long)sh->sector);
1364
1365         sh->check_state = check_state_check_result;
1366         set_bit(STRIPE_HANDLE, &sh->state);
1367         release_stripe(sh);
1368 }
1369
1370 static void ops_run_check_p(struct stripe_head *sh, struct raid5_percpu *percpu)
1371 {
1372         int disks = sh->disks;
1373         int pd_idx = sh->pd_idx;
1374         int qd_idx = sh->qd_idx;
1375         struct page *xor_dest;
1376         struct page **xor_srcs = percpu->scribble;
1377         struct dma_async_tx_descriptor *tx;
1378         struct async_submit_ctl submit;
1379         int count;
1380         int i;
1381
1382         pr_debug("%s: stripe %llu\n", __func__,
1383                 (unsigned long long)sh->sector);
1384
1385         count = 0;
1386         xor_dest = sh->dev[pd_idx].page;
1387         xor_srcs[count++] = xor_dest;
1388         for (i = disks; i--; ) {
1389                 if (i == pd_idx || i == qd_idx)
1390                         continue;
1391                 xor_srcs[count++] = sh->dev[i].page;
1392         }
1393
1394         init_async_submit(&submit, 0, NULL, NULL, NULL,
1395                           to_addr_conv(sh, percpu));
1396         tx = async_xor_val(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
1397                            &sh->ops.zero_sum_result, &submit);
1398
1399         atomic_inc(&sh->count);
1400         init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_check, sh, NULL);
1401         tx = async_trigger_callback(&submit);
1402 }
1403
1404 static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu, int checkp)
1405 {
1406         struct page **srcs = percpu->scribble;
1407         struct async_submit_ctl submit;
1408         int count;
1409
1410         pr_debug("%s: stripe %llu checkp: %d\n", __func__,
1411                 (unsigned long long)sh->sector, checkp);
1412
1413         count = set_syndrome_sources(srcs, sh);
1414         if (!checkp)
1415                 srcs[count] = NULL;
1416
1417         atomic_inc(&sh->count);
1418         init_async_submit(&submit, ASYNC_TX_ACK, NULL, ops_complete_check,
1419                           sh, to_addr_conv(sh, percpu));
1420         async_syndrome_val(srcs, 0, count+2, STRIPE_SIZE,
1421                            &sh->ops.zero_sum_result, percpu->spare_page, &submit);
1422 }
1423
1424 static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
1425 {
1426         int overlap_clear = 0, i, disks = sh->disks;
1427         struct dma_async_tx_descriptor *tx = NULL;
1428         struct r5conf *conf = sh->raid_conf;
1429         int level = conf->level;
1430         struct raid5_percpu *percpu;
1431         unsigned long cpu;
1432
1433         cpu = get_cpu();
1434         percpu = per_cpu_ptr(conf->percpu, cpu);
1435         if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
1436                 ops_run_biofill(sh);
1437                 overlap_clear++;
1438         }
1439
1440         if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
1441                 if (level < 6)
1442                         tx = ops_run_compute5(sh, percpu);
1443                 else {
1444                         if (sh->ops.target2 < 0 || sh->ops.target < 0)
1445                                 tx = ops_run_compute6_1(sh, percpu);
1446                         else
1447                                 tx = ops_run_compute6_2(sh, percpu);
1448                 }
1449                 /* terminate the chain if reconstruct is not set to be run */
1450                 if (tx && !test_bit(STRIPE_OP_RECONSTRUCT, &ops_request))
1451                         async_tx_ack(tx);
1452         }
1453
1454         if (test_bit(STRIPE_OP_PREXOR, &ops_request))
1455                 tx = ops_run_prexor(sh, percpu, tx);
1456
1457         if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
1458                 tx = ops_run_biodrain(sh, tx);
1459                 overlap_clear++;
1460         }
1461
1462         if (test_bit(STRIPE_OP_RECONSTRUCT, &ops_request)) {
1463                 if (level < 6)
1464                         ops_run_reconstruct5(sh, percpu, tx);
1465                 else
1466                         ops_run_reconstruct6(sh, percpu, tx);
1467         }
1468
1469         if (test_bit(STRIPE_OP_CHECK, &ops_request)) {
1470                 if (sh->check_state == check_state_run)
1471                         ops_run_check_p(sh, percpu);
1472                 else if (sh->check_state == check_state_run_q)
1473                         ops_run_check_pq(sh, percpu, 0);
1474                 else if (sh->check_state == check_state_run_pq)
1475                         ops_run_check_pq(sh, percpu, 1);
1476                 else
1477                         BUG();
1478         }
1479
1480         if (overlap_clear)
1481                 for (i = disks; i--; ) {
1482                         struct r5dev *dev = &sh->dev[i];
1483                         if (test_and_clear_bit(R5_Overlap, &dev->flags))
1484                                 wake_up(&sh->raid_conf->wait_for_overlap);
1485                 }
1486         put_cpu();
1487 }
1488
1489 static int grow_one_stripe(struct r5conf *conf)
1490 {
1491         struct stripe_head *sh;
1492         sh = kmem_cache_zalloc(conf->slab_cache, GFP_KERNEL);
1493         if (!sh)
1494                 return 0;
1495
1496         sh->raid_conf = conf;
1497
1498         spin_lock_init(&sh->stripe_lock);
1499
1500         if (grow_buffers(sh)) {
1501                 shrink_buffers(sh);
1502                 kmem_cache_free(conf->slab_cache, sh);
1503                 return 0;
1504         }
1505         /* we just created an active stripe so... */
1506         atomic_set(&sh->count, 1);
1507         atomic_inc(&conf->active_stripes);
1508         INIT_LIST_HEAD(&sh->lru);
1509         release_stripe(sh);
1510         return 1;
1511 }
1512
1513 static int grow_stripes(struct r5conf *conf, int num)
1514 {
1515         struct kmem_cache *sc;
1516         int devs = max(conf->raid_disks, conf->previous_raid_disks);
1517
1518         if (conf->mddev->gendisk)
1519                 sprintf(conf->cache_name[0],
1520                         "raid%d-%s", conf->level, mdname(conf->mddev));
1521         else
1522                 sprintf(conf->cache_name[0],
1523                         "raid%d-%p", conf->level, conf->mddev);
1524         sprintf(conf->cache_name[1], "%s-alt", conf->cache_name[0]);
1525
1526         conf->active_name = 0;
1527         sc = kmem_cache_create(conf->cache_name[conf->active_name],
1528                                sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
1529                                0, 0, NULL);
1530         if (!sc)
1531                 return 1;
1532         conf->slab_cache = sc;
1533         conf->pool_size = devs;
1534         while (num--)
1535                 if (!grow_one_stripe(conf))
1536                         return 1;
1537         return 0;
1538 }
1539
1540 /**
1541  * scribble_len - return the required size of the scribble region
1542  * @num - total number of disks in the array
1543  *
1544  * The size must be enough to contain:
1545  * 1/ a struct page pointer for each device in the array +2
1546  * 2/ room to convert each entry in (1) to its corresponding dma
1547  *    (dma_map_page()) or page (page_address()) address.
1548  *
1549  * Note: the +2 is for the destination buffers of the ddf/raid6 case where we
1550  * calculate over all devices (not just the data blocks), using zeros in place
1551  * of the P and Q blocks.
1552  */
1553 static size_t scribble_len(int num)
1554 {
1555         size_t len;
1556
1557         len = sizeof(struct page *) * (num+2) + sizeof(addr_conv_t) * (num+2);
1558
1559         return len;
1560 }
1561
1562 static int resize_stripes(struct r5conf *conf, int newsize)
1563 {
1564         /* Make all the stripes able to hold 'newsize' devices.
1565          * New slots in each stripe get 'page' set to a new page.
1566          *
1567          * This happens in stages:
1568          * 1/ create a new kmem_cache and allocate the required number of
1569          *    stripe_heads.
1570          * 2/ gather all the old stripe_heads and transfer the pages across
1571          *    to the new stripe_heads.  This will have the side effect of
1572          *    freezing the array as once all stripe_heads have been collected,
1573          *    no IO will be possible.  Old stripe heads are freed once their
1574          *    pages have been transferred over, and the old kmem_cache is
1575          *    freed when all stripes are done.
1576          * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
1577          *    we simple return a failre status - no need to clean anything up.
1578          * 4/ allocate new pages for the new slots in the new stripe_heads.
1579          *    If this fails, we don't bother trying the shrink the
1580          *    stripe_heads down again, we just leave them as they are.
1581          *    As each stripe_head is processed the new one is released into
1582          *    active service.
1583          *
1584          * Once step2 is started, we cannot afford to wait for a write,
1585          * so we use GFP_NOIO allocations.
1586          */
1587         struct stripe_head *osh, *nsh;
1588         LIST_HEAD(newstripes);
1589         struct disk_info *ndisks;
1590         unsigned long cpu;
1591         int err;
1592         struct kmem_cache *sc;
1593         int i;
1594
1595         if (newsize <= conf->pool_size)
1596                 return 0; /* never bother to shrink */
1597
1598         err = md_allow_write(conf->mddev);
1599         if (err)
1600                 return err;
1601
1602         /* Step 1 */
1603         sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
1604                                sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
1605                                0, 0, NULL);
1606         if (!sc)
1607                 return -ENOMEM;
1608
1609         for (i = conf->max_nr_stripes; i; i--) {
1610                 nsh = kmem_cache_zalloc(sc, GFP_KERNEL);
1611                 if (!nsh)
1612                         break;
1613
1614                 nsh->raid_conf = conf;
1615                 spin_lock_init(&nsh->stripe_lock);
1616
1617                 list_add(&nsh->lru, &newstripes);
1618         }
1619         if (i) {
1620                 /* didn't get enough, give up */
1621                 while (!list_empty(&newstripes)) {
1622                         nsh = list_entry(newstripes.next, struct stripe_head, lru);
1623                         list_del(&nsh->lru);
1624                         kmem_cache_free(sc, nsh);
1625                 }
1626                 kmem_cache_destroy(sc);
1627                 return -ENOMEM;
1628         }
1629         /* Step 2 - Must use GFP_NOIO now.
1630          * OK, we have enough stripes, start collecting inactive
1631          * stripes and copying them over
1632          */
1633         list_for_each_entry(nsh, &newstripes, lru) {
1634                 spin_lock_irq(&conf->device_lock);
1635                 wait_event_lock_irq(conf->wait_for_stripe,
1636                                     !list_empty(&conf->inactive_list),
1637                                     conf->device_lock);
1638                 osh = get_free_stripe(conf);
1639                 spin_unlock_irq(&conf->device_lock);
1640                 atomic_set(&nsh->count, 1);
1641                 for(i=0; i<conf->pool_size; i++)
1642                         nsh->dev[i].page = osh->dev[i].page;
1643                 for( ; i<newsize; i++)
1644                         nsh->dev[i].page = NULL;
1645                 kmem_cache_free(conf->slab_cache, osh);
1646         }
1647         kmem_cache_destroy(conf->slab_cache);
1648
1649         /* Step 3.
1650          * At this point, we are holding all the stripes so the array
1651          * is completely stalled, so now is a good time to resize
1652          * conf->disks and the scribble region
1653          */
1654         ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
1655         if (ndisks) {
1656                 for (i=0; i<conf->raid_disks; i++)
1657                         ndisks[i] = conf->disks[i];
1658                 kfree(conf->disks);
1659                 conf->disks = ndisks;
1660         } else
1661                 err = -ENOMEM;
1662
1663         get_online_cpus();
1664         conf->scribble_len = scribble_len(newsize);
1665         for_each_present_cpu(cpu) {
1666                 struct raid5_percpu *percpu;
1667                 void *scribble;
1668
1669                 percpu = per_cpu_ptr(conf->percpu, cpu);
1670                 scribble = kmalloc(conf->scribble_len, GFP_NOIO);
1671
1672                 if (scribble) {
1673                         kfree(percpu->scribble);
1674                         percpu->scribble = scribble;
1675                 } else {
1676                         err = -ENOMEM;
1677                         break;
1678                 }
1679         }
1680         put_online_cpus();
1681
1682         /* Step 4, return new stripes to service */
1683         while(!list_empty(&newstripes)) {
1684                 nsh = list_entry(newstripes.next, struct stripe_head, lru);
1685                 list_del_init(&nsh->lru);
1686
1687                 for (i=conf->raid_disks; i < newsize; i++)
1688                         if (nsh->dev[i].page == NULL) {
1689                                 struct page *p = alloc_page(GFP_NOIO);
1690                                 nsh->dev[i].page = p;
1691                                 if (!p)
1692                                         err = -ENOMEM;
1693                         }
1694                 release_stripe(nsh);
1695         }
1696         /* critical section pass, GFP_NOIO no longer needed */
1697
1698         conf->slab_cache = sc;
1699         conf->active_name = 1-conf->active_name;
1700         conf->pool_size = newsize;
1701         return err;
1702 }
1703
1704 static int drop_one_stripe(struct r5conf *conf)
1705 {
1706         struct stripe_head *sh;
1707
1708         spin_lock_irq(&conf->device_lock);
1709         sh = get_free_stripe(conf);
1710         spin_unlock_irq(&conf->device_lock);
1711         if (!sh)
1712                 return 0;
1713         BUG_ON(atomic_read(&sh->count));
1714         shrink_buffers(sh);
1715         kmem_cache_free(conf->slab_cache, sh);
1716         atomic_dec(&conf->active_stripes);
1717         return 1;
1718 }
1719
1720 static void shrink_stripes(struct r5conf *conf)
1721 {
1722         while (drop_one_stripe(conf))
1723                 ;
1724
1725         if (conf->slab_cache)
1726                 kmem_cache_destroy(conf->slab_cache);
1727         conf->slab_cache = NULL;
1728 }
1729
1730 static void raid5_end_read_request(struct bio * bi, int error)
1731 {
1732         struct stripe_head *sh = bi->bi_private;
1733         struct r5conf *conf = sh->raid_conf;
1734         int disks = sh->disks, i;
1735         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1736         char b[BDEVNAME_SIZE];
1737         struct md_rdev *rdev = NULL;
1738         sector_t s;
1739
1740         for (i=0 ; i<disks; i++)
1741                 if (bi == &sh->dev[i].req)
1742                         break;
1743
1744         pr_debug("end_read_request %llu/%d, count: %d, uptodate %d.\n",
1745                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
1746                 uptodate);
1747         if (i == disks) {
1748                 BUG();
1749                 return;
1750         }
1751         if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
1752                 /* If replacement finished while this request was outstanding,
1753                  * 'replacement' might be NULL already.
1754                  * In that case it moved down to 'rdev'.
1755                  * rdev is not removed until all requests are finished.
1756                  */
1757                 rdev = conf->disks[i].replacement;
1758         if (!rdev)
1759                 rdev = conf->disks[i].rdev;
1760
1761         if (use_new_offset(conf, sh))
1762                 s = sh->sector + rdev->new_data_offset;
1763         else
1764                 s = sh->sector + rdev->data_offset;
1765         if (uptodate) {
1766                 set_bit(R5_UPTODATE, &sh->dev[i].flags);
1767                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
1768                         /* Note that this cannot happen on a
1769                          * replacement device.  We just fail those on
1770                          * any error
1771                          */
1772                         printk_ratelimited(
1773                                 KERN_INFO
1774                                 "md/raid:%s: read error corrected"
1775                                 " (%lu sectors at %llu on %s)\n",
1776                                 mdname(conf->mddev), STRIPE_SECTORS,
1777                                 (unsigned long long)s,
1778                                 bdevname(rdev->bdev, b));
1779                         atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
1780                         clear_bit(R5_ReadError, &sh->dev[i].flags);
1781                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
1782                 } else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
1783                         clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
1784
1785                 if (atomic_read(&rdev->read_errors))
1786                         atomic_set(&rdev->read_errors, 0);
1787         } else {
1788                 const char *bdn = bdevname(rdev->bdev, b);
1789                 int retry = 0;
1790                 int set_bad = 0;
1791
1792                 clear_bit(R5_UPTODATE, &sh->dev[i].flags);
1793                 atomic_inc(&rdev->read_errors);
1794                 if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
1795                         printk_ratelimited(
1796                                 KERN_WARNING
1797                                 "md/raid:%s: read error on replacement device "
1798                                 "(sector %llu on %s).\n",
1799                                 mdname(conf->mddev),
1800                                 (unsigned long long)s,
1801                                 bdn);
1802                 else if (conf->mddev->degraded >= conf->max_degraded) {
1803                         set_bad = 1;
1804                         printk_ratelimited(
1805                                 KERN_WARNING
1806                                 "md/raid:%s: read error not correctable "
1807                                 "(sector %llu on %s).\n",
1808                                 mdname(conf->mddev),
1809                                 (unsigned long long)s,
1810                                 bdn);
1811                 } else if (test_bit(R5_ReWrite, &sh->dev[i].flags)) {
1812                         /* Oh, no!!! */
1813                         set_bad = 1;
1814                         printk_ratelimited(
1815                                 KERN_WARNING
1816                                 "md/raid:%s: read error NOT corrected!! "
1817                                 "(sector %llu on %s).\n",
1818                                 mdname(conf->mddev),
1819                                 (unsigned long long)s,
1820                                 bdn);
1821                 } else if (atomic_read(&rdev->read_errors)
1822                          > conf->max_nr_stripes)
1823                         printk(KERN_WARNING
1824                                "md/raid:%s: Too many read errors, failing device %s.\n",
1825                                mdname(conf->mddev), bdn);
1826                 else
1827                         retry = 1;
1828                 if (retry)
1829                         if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags)) {
1830                                 set_bit(R5_ReadError, &sh->dev[i].flags);
1831                                 clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
1832                         } else
1833                                 set_bit(R5_ReadNoMerge, &sh->dev[i].flags);
1834                 else {
1835                         clear_bit(R5_ReadError, &sh->dev[i].flags);
1836                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
1837                         if (!(set_bad
1838                               && test_bit(In_sync, &rdev->flags)
1839                               && rdev_set_badblocks(
1840                                       rdev, sh->sector, STRIPE_SECTORS, 0)))
1841                                 md_error(conf->mddev, rdev);
1842                 }
1843         }
1844         rdev_dec_pending(rdev, conf->mddev);
1845         clear_bit(R5_LOCKED, &sh->dev[i].flags);
1846         set_bit(STRIPE_HANDLE, &sh->state);
1847         release_stripe(sh);
1848 }
1849
1850 static void raid5_end_write_request(struct bio *bi, int error)
1851 {
1852         struct stripe_head *sh = bi->bi_private;
1853         struct r5conf *conf = sh->raid_conf;
1854         int disks = sh->disks, i;
1855         struct md_rdev *uninitialized_var(rdev);
1856         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1857         sector_t first_bad;
1858         int bad_sectors;
1859         int replacement = 0;
1860
1861         for (i = 0 ; i < disks; i++) {
1862                 if (bi == &sh->dev[i].req) {
1863                         rdev = conf->disks[i].rdev;
1864                         break;
1865                 }
1866                 if (bi == &sh->dev[i].rreq) {
1867                         rdev = conf->disks[i].replacement;
1868                         if (rdev)
1869                                 replacement = 1;
1870                         else
1871                                 /* rdev was removed and 'replacement'
1872                                  * replaced it.  rdev is not removed
1873                                  * until all requests are finished.
1874                                  */
1875                                 rdev = conf->disks[i].rdev;
1876                         break;
1877                 }
1878         }
1879         pr_debug("end_write_request %llu/%d, count %d, uptodate: %d.\n",
1880                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
1881                 uptodate);
1882         if (i == disks) {
1883                 BUG();
1884                 return;
1885         }
1886
1887         if (replacement) {
1888                 if (!uptodate)
1889                         md_error(conf->mddev, rdev);
1890                 else if (is_badblock(rdev, sh->sector,
1891                                      STRIPE_SECTORS,
1892                                      &first_bad, &bad_sectors))
1893                         set_bit(R5_MadeGoodRepl, &sh->dev[i].flags);
1894         } else {
1895                 if (!uptodate) {
1896                         set_bit(WriteErrorSeen, &rdev->flags);
1897                         set_bit(R5_WriteError, &sh->dev[i].flags);
1898                         if (!test_and_set_bit(WantReplacement, &rdev->flags))
1899                                 set_bit(MD_RECOVERY_NEEDED,
1900                                         &rdev->mddev->recovery);
1901                 } else if (is_badblock(rdev, sh->sector,
1902                                        STRIPE_SECTORS,
1903                                        &first_bad, &bad_sectors)) {
1904                         set_bit(R5_MadeGood, &sh->dev[i].flags);
1905                         if (test_bit(R5_ReadError, &sh->dev[i].flags))
1906                                 /* That was a successful write so make
1907                                  * sure it looks like we already did
1908                                  * a re-write.
1909                                  */
1910                                 set_bit(R5_ReWrite, &sh->dev[i].flags);
1911                 }
1912         }
1913         rdev_dec_pending(rdev, conf->mddev);
1914
1915         if (!test_and_clear_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags))
1916                 clear_bit(R5_LOCKED, &sh->dev[i].flags);
1917         set_bit(STRIPE_HANDLE, &sh->state);
1918         release_stripe(sh);
1919 }
1920
1921 static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous);
1922
1923 static void raid5_build_block(struct stripe_head *sh, int i, int previous)
1924 {
1925         struct r5dev *dev = &sh->dev[i];
1926
1927         bio_init(&dev->req);
1928         dev->req.bi_io_vec = &dev->vec;
1929         dev->req.bi_vcnt++;
1930         dev->req.bi_max_vecs++;
1931         dev->req.bi_private = sh;
1932         dev->vec.bv_page = dev->page;
1933
1934         bio_init(&dev->rreq);
1935         dev->rreq.bi_io_vec = &dev->rvec;
1936         dev->rreq.bi_vcnt++;
1937         dev->rreq.bi_max_vecs++;
1938         dev->rreq.bi_private = sh;
1939         dev->rvec.bv_page = dev->page;
1940
1941         dev->flags = 0;
1942         dev->sector = compute_blocknr(sh, i, previous);
1943 }
1944
1945 static void error(struct mddev *mddev, struct md_rdev *rdev)
1946 {
1947         char b[BDEVNAME_SIZE];
1948         struct r5conf *conf = mddev->private;
1949         unsigned long flags;
1950         pr_debug("raid456: error called\n");
1951
1952         spin_lock_irqsave(&conf->device_lock, flags);
1953         clear_bit(In_sync, &rdev->flags);
1954         mddev->degraded = calc_degraded(conf);
1955         spin_unlock_irqrestore(&conf->device_lock, flags);
1956         set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1957
1958         set_bit(Blocked, &rdev->flags);
1959         set_bit(Faulty, &rdev->flags);
1960         set_bit(MD_CHANGE_DEVS, &mddev->flags);
1961         printk(KERN_ALERT
1962                "md/raid:%s: Disk failure on %s, disabling device.\n"
1963                "md/raid:%s: Operation continuing on %d devices.\n",
1964                mdname(mddev),
1965                bdevname(rdev->bdev, b),
1966                mdname(mddev),
1967                conf->raid_disks - mddev->degraded);
1968 }
1969
1970 /*
1971  * Input: a 'big' sector number,
1972  * Output: index of the data and parity disk, and the sector # in them.
1973  */
1974 static sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
1975                                      int previous, int *dd_idx,
1976                                      struct stripe_head *sh)
1977 {
1978         sector_t stripe, stripe2;
1979         sector_t chunk_number;
1980         unsigned int chunk_offset;
1981         int pd_idx, qd_idx;
1982         int ddf_layout = 0;
1983         sector_t new_sector;
1984         int algorithm = previous ? conf->prev_algo
1985                                  : conf->algorithm;
1986         int sectors_per_chunk = previous ? conf->prev_chunk_sectors
1987                                          : conf->chunk_sectors;
1988         int raid_disks = previous ? conf->previous_raid_disks
1989                                   : conf->raid_disks;
1990         int data_disks = raid_disks - conf->max_degraded;
1991
1992         /* First compute the information on this sector */
1993
1994         /*
1995          * Compute the chunk number and the sector offset inside the chunk
1996          */
1997         chunk_offset = sector_div(r_sector, sectors_per_chunk);
1998         chunk_number = r_sector;
1999
2000         /*
2001          * Compute the stripe number
2002          */
2003         stripe = chunk_number;
2004         *dd_idx = sector_div(stripe, data_disks);
2005         stripe2 = stripe;
2006         /*
2007          * Select the parity disk based on the user selected algorithm.
2008          */
2009         pd_idx = qd_idx = -1;
2010         switch(conf->level) {
2011         case 4:
2012                 pd_idx = data_disks;
2013                 break;
2014         case 5:
2015                 switch (algorithm) {
2016                 case ALGORITHM_LEFT_ASYMMETRIC:
2017                         pd_idx = data_disks - sector_div(stripe2, raid_disks);
2018                         if (*dd_idx >= pd_idx)
2019                                 (*dd_idx)++;
2020                         break;
2021                 case ALGORITHM_RIGHT_ASYMMETRIC:
2022                         pd_idx = sector_div(stripe2, raid_disks);
2023                         if (*dd_idx >= pd_idx)
2024                                 (*dd_idx)++;
2025                         break;
2026                 case ALGORITHM_LEFT_SYMMETRIC:
2027                         pd_idx = data_disks - sector_div(stripe2, raid_disks);
2028                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2029                         break;
2030                 case ALGORITHM_RIGHT_SYMMETRIC:
2031                         pd_idx = sector_div(stripe2, raid_disks);
2032                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2033                         break;
2034                 case ALGORITHM_PARITY_0:
2035                         pd_idx = 0;
2036                         (*dd_idx)++;
2037                         break;
2038                 case ALGORITHM_PARITY_N:
2039                         pd_idx = data_disks;
2040                         break;
2041                 default:
2042                         BUG();
2043                 }
2044                 break;
2045         case 6:
2046
2047                 switch (algorithm) {
2048                 case ALGORITHM_LEFT_ASYMMETRIC:
2049                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2050                         qd_idx = pd_idx + 1;
2051                         if (pd_idx == raid_disks-1) {
2052                                 (*dd_idx)++;    /* Q D D D P */
2053                                 qd_idx = 0;
2054                         } else if (*dd_idx >= pd_idx)
2055                                 (*dd_idx) += 2; /* D D P Q D */
2056                         break;
2057                 case ALGORITHM_RIGHT_ASYMMETRIC:
2058                         pd_idx = sector_div(stripe2, raid_disks);
2059                         qd_idx = pd_idx + 1;
2060                         if (pd_idx == raid_disks-1) {
2061                                 (*dd_idx)++;    /* Q D D D P */
2062                                 qd_idx = 0;
2063                         } else if (*dd_idx >= pd_idx)
2064                                 (*dd_idx) += 2; /* D D P Q D */
2065                         break;
2066                 case ALGORITHM_LEFT_SYMMETRIC:
2067                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2068                         qd_idx = (pd_idx + 1) % raid_disks;
2069                         *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2070                         break;
2071                 case ALGORITHM_RIGHT_SYMMETRIC:
2072                         pd_idx = sector_div(stripe2, raid_disks);
2073                         qd_idx = (pd_idx + 1) % raid_disks;
2074                         *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2075                         break;
2076
2077                 case ALGORITHM_PARITY_0:
2078                         pd_idx = 0;
2079                         qd_idx = 1;
2080                         (*dd_idx) += 2;
2081                         break;
2082                 case ALGORITHM_PARITY_N:
2083                         pd_idx = data_disks;
2084                         qd_idx = data_disks + 1;
2085                         break;
2086
2087                 case ALGORITHM_ROTATING_ZERO_RESTART:
2088                         /* Exactly the same as RIGHT_ASYMMETRIC, but or
2089                          * of blocks for computing Q is different.
2090                          */
2091                         pd_idx = sector_div(stripe2, raid_disks);
2092                         qd_idx = pd_idx + 1;
2093                         if (pd_idx == raid_disks-1) {
2094                                 (*dd_idx)++;    /* Q D D D P */
2095                                 qd_idx = 0;
2096                         } else if (*dd_idx >= pd_idx)
2097                                 (*dd_idx) += 2; /* D D P Q D */
2098                         ddf_layout = 1;
2099                         break;
2100
2101                 case ALGORITHM_ROTATING_N_RESTART:
2102                         /* Same a left_asymmetric, by first stripe is
2103                          * D D D P Q  rather than
2104                          * Q D D D P
2105                          */
2106                         stripe2 += 1;
2107                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2108                         qd_idx = pd_idx + 1;
2109                         if (pd_idx == raid_disks-1) {
2110                                 (*dd_idx)++;    /* Q D D D P */
2111                                 qd_idx = 0;
2112                         } else if (*dd_idx >= pd_idx)
2113                                 (*dd_idx) += 2; /* D D P Q D */
2114                         ddf_layout = 1;
2115                         break;
2116
2117                 case ALGORITHM_ROTATING_N_CONTINUE:
2118                         /* Same as left_symmetric but Q is before P */
2119                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2120                         qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
2121                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2122                         ddf_layout = 1;
2123                         break;
2124
2125                 case ALGORITHM_LEFT_ASYMMETRIC_6:
2126                         /* RAID5 left_asymmetric, with Q on last device */
2127                         pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2128                         if (*dd_idx >= pd_idx)
2129                                 (*dd_idx)++;
2130                         qd_idx = raid_disks - 1;
2131                         break;
2132
2133                 case ALGORITHM_RIGHT_ASYMMETRIC_6:
2134                         pd_idx = sector_div(stripe2, raid_disks-1);
2135                         if (*dd_idx >= pd_idx)
2136                                 (*dd_idx)++;
2137                         qd_idx = raid_disks - 1;
2138                         break;
2139
2140                 case ALGORITHM_LEFT_SYMMETRIC_6:
2141                         pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2142                         *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2143                         qd_idx = raid_disks - 1;
2144                         break;
2145
2146                 case ALGORITHM_RIGHT_SYMMETRIC_6:
2147                         pd_idx = sector_div(stripe2, raid_disks-1);
2148                         *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2149                         qd_idx = raid_disks - 1;
2150                         break;
2151
2152                 case ALGORITHM_PARITY_0_6:
2153                         pd_idx = 0;
2154                         (*dd_idx)++;
2155                         qd_idx = raid_disks - 1;
2156                         break;
2157
2158                 default:
2159                         BUG();
2160                 }
2161                 break;
2162         }
2163
2164         if (sh) {
2165                 sh->pd_idx = pd_idx;
2166                 sh->qd_idx = qd_idx;
2167                 sh->ddf_layout = ddf_layout;
2168         }
2169         /*
2170          * Finally, compute the new sector number
2171          */
2172         new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
2173         return new_sector;
2174 }
2175
2176
2177 static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous)
2178 {
2179         struct r5conf *conf = sh->raid_conf;
2180         int raid_disks = sh->disks;
2181         int data_disks = raid_disks - conf->max_degraded;
2182         sector_t new_sector = sh->sector, check;
2183         int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2184                                          : conf->chunk_sectors;
2185         int algorithm = previous ? conf->prev_algo
2186                                  : conf->algorithm;
2187         sector_t stripe;
2188         int chunk_offset;
2189         sector_t chunk_number;
2190         int dummy1, dd_idx = i;
2191         sector_t r_sector;
2192         struct stripe_head sh2;
2193
2194
2195         chunk_offset = sector_div(new_sector, sectors_per_chunk);
2196         stripe = new_sector;
2197
2198         if (i == sh->pd_idx)
2199                 return 0;
2200         switch(conf->level) {
2201         case 4: break;
2202         case 5:
2203                 switch (algorithm) {
2204                 case ALGORITHM_LEFT_ASYMMETRIC:
2205                 case ALGORITHM_RIGHT_ASYMMETRIC:
2206                         if (i > sh->pd_idx)
2207                                 i--;
2208                         break;
2209                 case ALGORITHM_LEFT_SYMMETRIC:
2210                 case ALGORITHM_RIGHT_SYMMETRIC:
2211                         if (i < sh->pd_idx)
2212                                 i += raid_disks;
2213                         i -= (sh->pd_idx + 1);
2214                         break;
2215                 case ALGORITHM_PARITY_0:
2216                         i -= 1;
2217                         break;
2218                 case ALGORITHM_PARITY_N:
2219                         break;
2220                 default:
2221                         BUG();
2222                 }
2223                 break;
2224         case 6:
2225                 if (i == sh->qd_idx)
2226                         return 0; /* It is the Q disk */
2227                 switch (algorithm) {
2228                 case ALGORITHM_LEFT_ASYMMETRIC:
2229                 case ALGORITHM_RIGHT_ASYMMETRIC:
2230                 case ALGORITHM_ROTATING_ZERO_RESTART:
2231                 case ALGORITHM_ROTATING_N_RESTART:
2232                         if (sh->pd_idx == raid_disks-1)
2233                                 i--;    /* Q D D D P */
2234                         else if (i > sh->pd_idx)
2235                                 i -= 2; /* D D P Q D */
2236                         break;
2237                 case ALGORITHM_LEFT_SYMMETRIC:
2238                 case ALGORITHM_RIGHT_SYMMETRIC:
2239                         if (sh->pd_idx == raid_disks-1)
2240                                 i--; /* Q D D D P */
2241                         else {
2242                                 /* D D P Q D */
2243                                 if (i < sh->pd_idx)
2244                                         i += raid_disks;
2245                                 i -= (sh->pd_idx + 2);
2246                         }
2247                         break;
2248                 case ALGORITHM_PARITY_0:
2249                         i -= 2;
2250                         break;
2251                 case ALGORITHM_PARITY_N:
2252                         break;
2253                 case ALGORITHM_ROTATING_N_CONTINUE:
2254                         /* Like left_symmetric, but P is before Q */
2255                         if (sh->pd_idx == 0)
2256                                 i--;    /* P D D D Q */
2257                         else {
2258                                 /* D D Q P D */
2259                                 if (i < sh->pd_idx)
2260                                         i += raid_disks;
2261                                 i -= (sh->pd_idx + 1);
2262                         }
2263                         break;
2264                 case ALGORITHM_LEFT_ASYMMETRIC_6:
2265                 case ALGORITHM_RIGHT_ASYMMETRIC_6:
2266                         if (i > sh->pd_idx)
2267                                 i--;
2268                         break;
2269                 case ALGORITHM_LEFT_SYMMETRIC_6:
2270                 case ALGORITHM_RIGHT_SYMMETRIC_6:
2271                         if (i < sh->pd_idx)
2272                                 i += data_disks + 1;
2273                         i -= (sh->pd_idx + 1);
2274                         break;
2275                 case ALGORITHM_PARITY_0_6:
2276                         i -= 1;
2277                         break;
2278                 default:
2279                         BUG();
2280                 }
2281                 break;
2282         }
2283
2284         chunk_number = stripe * data_disks + i;
2285         r_sector = chunk_number * sectors_per_chunk + chunk_offset;
2286
2287         check = raid5_compute_sector(conf, r_sector,
2288                                      previous, &dummy1, &sh2);
2289         if (check != sh->sector || dummy1 != dd_idx || sh2.pd_idx != sh->pd_idx
2290                 || sh2.qd_idx != sh->qd_idx) {
2291                 printk(KERN_ERR "md/raid:%s: compute_blocknr: map not correct\n",
2292                        mdname(conf->mddev));
2293                 return 0;
2294         }
2295         return r_sector;
2296 }
2297
2298
2299 static void
2300 schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
2301                          int rcw, int expand)
2302 {
2303         int i, pd_idx = sh->pd_idx, disks = sh->disks;
2304         struct r5conf *conf = sh->raid_conf;
2305         int level = conf->level;
2306
2307         if (rcw) {
2308
2309                 for (i = disks; i--; ) {
2310                         struct r5dev *dev = &sh->dev[i];
2311
2312                         if (dev->towrite) {
2313                                 set_bit(R5_LOCKED, &dev->flags);
2314                                 set_bit(R5_Wantdrain, &dev->flags);
2315                                 if (!expand)
2316                                         clear_bit(R5_UPTODATE, &dev->flags);
2317                                 s->locked++;
2318                         }
2319                 }
2320                 /* if we are not expanding this is a proper write request, and
2321                  * there will be bios with new data to be drained into the
2322                  * stripe cache
2323                  */
2324                 if (!expand) {
2325                         if (!s->locked)
2326                                 /* False alarm, nothing to do */
2327                                 return;
2328                         sh->reconstruct_state = reconstruct_state_drain_run;
2329                         set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2330                 } else
2331                         sh->reconstruct_state = reconstruct_state_run;
2332
2333                 set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2334
2335                 if (s->locked + conf->max_degraded == disks)
2336                         if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
2337                                 atomic_inc(&conf->pending_full_writes);
2338         } else {
2339                 BUG_ON(level == 6);
2340                 BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
2341                         test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
2342
2343                 for (i = disks; i--; ) {
2344                         struct r5dev *dev = &sh->dev[i];
2345                         if (i == pd_idx)
2346                                 continue;
2347
2348                         if (dev->towrite &&
2349                             (test_bit(R5_UPTODATE, &dev->flags) ||
2350                              test_bit(R5_Wantcompute, &dev->flags))) {
2351                                 set_bit(R5_Wantdrain, &dev->flags);
2352                                 set_bit(R5_LOCKED, &dev->flags);
2353                                 clear_bit(R5_UPTODATE, &dev->flags);
2354                                 s->locked++;
2355                         }
2356                 }
2357                 if (!s->locked)
2358                         /* False alarm - nothing to do */
2359                         return;
2360                 sh->reconstruct_state = reconstruct_state_prexor_drain_run;
2361                 set_bit(STRIPE_OP_PREXOR, &s->ops_request);
2362                 set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2363                 set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2364         }
2365
2366         /* keep the parity disk(s) locked while asynchronous operations
2367          * are in flight
2368          */
2369         set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
2370         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
2371         s->locked++;
2372
2373         if (level == 6) {
2374                 int qd_idx = sh->qd_idx;
2375                 struct r5dev *dev = &sh->dev[qd_idx];
2376
2377                 set_bit(R5_LOCKED, &dev->flags);
2378                 clear_bit(R5_UPTODATE, &dev->flags);
2379                 s->locked++;
2380         }
2381
2382         pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
2383                 __func__, (unsigned long long)sh->sector,
2384                 s->locked, s->ops_request);
2385 }
2386
2387 /*
2388  * Each stripe/dev can have one or more bion attached.
2389  * toread/towrite point to the first in a chain.
2390  * The bi_next chain must be in order.
2391  */
2392 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
2393 {
2394         struct bio **bip;
2395         struct r5conf *conf = sh->raid_conf;
2396         int firstwrite=0;
2397
2398         pr_debug("adding bi b#%llu to stripe s#%llu\n",
2399                 (unsigned long long)bi->bi_sector,
2400                 (unsigned long long)sh->sector);
2401
2402         /*
2403          * If several bio share a stripe. The bio bi_phys_segments acts as a
2404          * reference count to avoid race. The reference count should already be
2405          * increased before this function is called (for example, in
2406          * make_request()), so other bio sharing this stripe will not free the
2407          * stripe. If a stripe is owned by one stripe, the stripe lock will
2408          * protect it.
2409          */
2410         spin_lock_irq(&sh->stripe_lock);
2411         if (forwrite) {
2412                 bip = &sh->dev[dd_idx].towrite;
2413                 if (*bip == NULL)
2414                         firstwrite = 1;
2415         } else
2416                 bip = &sh->dev[dd_idx].toread;
2417         while (*bip && (*bip)->bi_sector < bi->bi_sector) {
2418                 if (bio_end_sector(*bip) > bi->bi_sector)
2419                         goto overlap;
2420                 bip = & (*bip)->bi_next;
2421         }
2422         if (*bip && (*bip)->bi_sector < bio_end_sector(bi))
2423                 goto overlap;
2424
2425         BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
2426         if (*bip)
2427                 bi->bi_next = *bip;
2428         *bip = bi;
2429         raid5_inc_bi_active_stripes(bi);
2430
2431         if (forwrite) {
2432                 /* check if page is covered */
2433                 sector_t sector = sh->dev[dd_idx].sector;
2434                 for (bi=sh->dev[dd_idx].towrite;
2435                      sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
2436                              bi && bi->bi_sector <= sector;
2437                      bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
2438                         if (bio_end_sector(bi) >= sector)
2439                                 sector = bio_end_sector(bi);
2440                 }
2441                 if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
2442                         set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
2443         }
2444
2445         pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
2446                 (unsigned long long)(*bip)->bi_sector,
2447                 (unsigned long long)sh->sector, dd_idx);
2448         spin_unlock_irq(&sh->stripe_lock);
2449
2450         if (conf->mddev->bitmap && firstwrite) {
2451                 bitmap_startwrite(conf->mddev->bitmap, sh->sector,
2452                                   STRIPE_SECTORS, 0);
2453                 sh->bm_seq = conf->seq_flush+1;
2454                 set_bit(STRIPE_BIT_DELAY, &sh->state);
2455         }
2456         return 1;
2457
2458  overlap:
2459         set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
2460         spin_unlock_irq(&sh->stripe_lock);
2461         return 0;
2462 }
2463
2464 static void end_reshape(struct r5conf *conf);
2465
2466 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
2467                             struct stripe_head *sh)
2468 {
2469         int sectors_per_chunk =
2470                 previous ? conf->prev_chunk_sectors : conf->chunk_sectors;
2471         int dd_idx;
2472         int chunk_offset = sector_div(stripe, sectors_per_chunk);
2473         int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
2474
2475         raid5_compute_sector(conf,
2476                              stripe * (disks - conf->max_degraded)
2477                              *sectors_per_chunk + chunk_offset,
2478                              previous,
2479                              &dd_idx, sh);
2480 }
2481
2482 static void
2483 handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
2484                                 struct stripe_head_state *s, int disks,
2485                                 struct bio **return_bi)
2486 {
2487         int i;
2488         for (i = disks; i--; ) {
2489                 struct bio *bi;
2490                 int bitmap_end = 0;
2491
2492                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2493                         struct md_rdev *rdev;
2494                         rcu_read_lock();
2495                         rdev = rcu_dereference(conf->disks[i].rdev);
2496                         if (rdev && test_bit(In_sync, &rdev->flags))
2497                                 atomic_inc(&rdev->nr_pending);
2498                         else
2499                                 rdev = NULL;
2500                         rcu_read_unlock();
2501                         if (rdev) {
2502                                 if (!rdev_set_badblocks(
2503                                             rdev,
2504                                             sh->sector,
2505                                             STRIPE_SECTORS, 0))
2506                                         md_error(conf->mddev, rdev);
2507                                 rdev_dec_pending(rdev, conf->mddev);
2508                         }
2509                 }
2510                 spin_lock_irq(&sh->stripe_lock);
2511                 /* fail all writes first */
2512                 bi = sh->dev[i].towrite;
2513                 sh->dev[i].towrite = NULL;
2514                 spin_unlock_irq(&sh->stripe_lock);
2515                 if (bi)
2516                         bitmap_end = 1;
2517
2518                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2519                         wake_up(&conf->wait_for_overlap);
2520
2521                 while (bi && bi->bi_sector <
2522                         sh->dev[i].sector + STRIPE_SECTORS) {
2523                         struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
2524                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
2525                         if (!raid5_dec_bi_active_stripes(bi)) {
2526                                 md_write_end(conf->mddev);
2527                                 bi->bi_next = *return_bi;
2528                                 *return_bi = bi;
2529                         }
2530                         bi = nextbi;
2531                 }
2532                 if (bitmap_end)
2533                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2534                                 STRIPE_SECTORS, 0, 0);
2535                 bitmap_end = 0;
2536                 /* and fail all 'written' */
2537                 bi = sh->dev[i].written;
2538                 sh->dev[i].written = NULL;
2539                 if (bi) bitmap_end = 1;
2540                 while (bi && bi->bi_sector <
2541                        sh->dev[i].sector + STRIPE_SECTORS) {
2542                         struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
2543                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
2544                         if (!raid5_dec_bi_active_stripes(bi)) {
2545                                 md_write_end(conf->mddev);
2546                                 bi->bi_next = *return_bi;
2547                                 *return_bi = bi;
2548                         }
2549                         bi = bi2;
2550                 }
2551
2552                 /* fail any reads if this device is non-operational and
2553                  * the data has not reached the cache yet.
2554                  */
2555                 if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
2556                     (!test_bit(R5_Insync, &sh->dev[i].flags) ||
2557                       test_bit(R5_ReadError, &sh->dev[i].flags))) {
2558                         spin_lock_irq(&sh->stripe_lock);
2559                         bi = sh->dev[i].toread;
2560                         sh->dev[i].toread = NULL;
2561                         spin_unlock_irq(&sh->stripe_lock);
2562                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2563                                 wake_up(&conf->wait_for_overlap);
2564                         while (bi && bi->bi_sector <
2565                                sh->dev[i].sector + STRIPE_SECTORS) {
2566                                 struct bio *nextbi =
2567                                         r5_next_bio(bi, sh->dev[i].sector);
2568                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
2569                                 if (!raid5_dec_bi_active_stripes(bi)) {
2570                                         bi->bi_next = *return_bi;
2571                                         *return_bi = bi;
2572                                 }
2573                                 bi = nextbi;
2574                         }
2575                 }
2576                 if (bitmap_end)
2577                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2578                                         STRIPE_SECTORS, 0, 0);
2579                 /* If we were in the middle of a write the parity block might
2580                  * still be locked - so just clear all R5_LOCKED flags
2581                  */
2582                 clear_bit(R5_LOCKED, &sh->dev[i].flags);
2583         }
2584
2585         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2586                 if (atomic_dec_and_test(&conf->pending_full_writes))
2587                         md_wakeup_thread(conf->mddev->thread);
2588 }
2589
2590 static void
2591 handle_failed_sync(struct r5conf *conf, struct stripe_head *sh,
2592                    struct stripe_head_state *s)
2593 {
2594         int abort = 0;
2595         int i;
2596
2597         clear_bit(STRIPE_SYNCING, &sh->state);
2598         if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
2599                 wake_up(&conf->wait_for_overlap);
2600         s->syncing = 0;
2601         s->replacing = 0;
2602         /* There is nothing more to do for sync/check/repair.
2603          * Don't even need to abort as that is handled elsewhere
2604          * if needed, and not always wanted e.g. if there is a known
2605          * bad block here.
2606          * For recover/replace we need to record a bad block on all
2607          * non-sync devices, or abort the recovery
2608          */
2609         if (test_bit(MD_RECOVERY_RECOVER, &conf->mddev->recovery)) {
2610                 /* During recovery devices cannot be removed, so
2611                  * locking and refcounting of rdevs is not needed
2612                  */
2613                 for (i = 0; i < conf->raid_disks; i++) {
2614                         struct md_rdev *rdev = conf->disks[i].rdev;
2615                         if (rdev
2616                             && !test_bit(Faulty, &rdev->flags)
2617                             && !test_bit(In_sync, &rdev->flags)
2618                             && !rdev_set_badblocks(rdev, sh->sector,
2619                                                    STRIPE_SECTORS, 0))
2620                                 abort = 1;
2621                         rdev = conf->disks[i].replacement;
2622                         if (rdev
2623                             && !test_bit(Faulty, &rdev->flags)
2624                             && !test_bit(In_sync, &rdev->flags)
2625                             && !rdev_set_badblocks(rdev, sh->sector,
2626                                                    STRIPE_SECTORS, 0))
2627                                 abort = 1;
2628                 }
2629                 if (abort)
2630                         conf->recovery_disabled =
2631                                 conf->mddev->recovery_disabled;
2632         }
2633         md_done_sync(conf->mddev, STRIPE_SECTORS, !abort);
2634 }
2635
2636 static int want_replace(struct stripe_head *sh, int disk_idx)
2637 {
2638         struct md_rdev *rdev;
2639         int rv = 0;
2640         /* Doing recovery so rcu locking not required */
2641         rdev = sh->raid_conf->disks[disk_idx].replacement;
2642         if (rdev
2643             && !test_bit(Faulty, &rdev->flags)
2644             && !test_bit(In_sync, &rdev->flags)
2645             && (rdev->recovery_offset <= sh->sector
2646                 || rdev->mddev->recovery_cp <= sh->sector))
2647                 rv = 1;
2648
2649         return rv;
2650 }
2651
2652 /* fetch_block - checks the given member device to see if its data needs
2653  * to be read or computed to satisfy a request.
2654  *
2655  * Returns 1 when no more member devices need to be checked, otherwise returns
2656  * 0 to tell the loop in handle_stripe_fill to continue
2657  */
2658 static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
2659                        int disk_idx, int disks)
2660 {
2661         struct r5dev *dev = &sh->dev[disk_idx];
2662         struct r5dev *fdev[2] = { &sh->dev[s->failed_num[0]],
2663                                   &sh->dev[s->failed_num[1]] };
2664
2665         /* is the data in this block needed, and can we get it? */
2666         if (!test_bit(R5_LOCKED, &dev->flags) &&
2667             !test_bit(R5_UPTODATE, &dev->flags) &&
2668             (dev->toread ||
2669              (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
2670              s->syncing || s->expanding ||
2671              (s->replacing && want_replace(sh, disk_idx)) ||
2672              (s->failed >= 1 && fdev[0]->toread) ||
2673              (s->failed >= 2 && fdev[1]->toread) ||
2674              (sh->raid_conf->level <= 5 && s->failed && fdev[0]->towrite &&
2675               !test_bit(R5_OVERWRITE, &fdev[0]->flags)) ||
2676              (sh->raid_conf->level == 6 && s->failed && s->to_write))) {
2677                 /* we would like to get this block, possibly by computing it,
2678                  * otherwise read it if the backing disk is insync
2679                  */
2680                 BUG_ON(test_bit(R5_Wantcompute, &dev->flags));
2681                 BUG_ON(test_bit(R5_Wantread, &dev->flags));
2682                 if ((s->uptodate == disks - 1) &&
2683                     (s->failed && (disk_idx == s->failed_num[0] ||
2684                                    disk_idx == s->failed_num[1]))) {
2685                         /* have disk failed, and we're requested to fetch it;
2686                          * do compute it
2687                          */
2688                         pr_debug("Computing stripe %llu block %d\n",
2689                                (unsigned long long)sh->sector, disk_idx);
2690                         set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2691                         set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2692                         set_bit(R5_Wantcompute, &dev->flags);
2693                         sh->ops.target = disk_idx;
2694                         sh->ops.target2 = -1; /* no 2nd target */
2695                         s->req_compute = 1;
2696                         /* Careful: from this point on 'uptodate' is in the eye
2697                          * of raid_run_ops which services 'compute' operations
2698                          * before writes. R5_Wantcompute flags a block that will
2699                          * be R5_UPTODATE by the time it is needed for a
2700                          * subsequent operation.
2701                          */
2702                         s->uptodate++;
2703                         return 1;
2704                 } else if (s->uptodate == disks-2 && s->failed >= 2) {
2705                         /* Computing 2-failure is *very* expensive; only
2706                          * do it if failed >= 2
2707                          */
2708                         int other;
2709                         for (other = disks; other--; ) {
2710                                 if (other == disk_idx)
2711                                         continue;
2712                                 if (!test_bit(R5_UPTODATE,
2713                                       &sh->dev[other].flags))
2714                                         break;
2715                         }
2716                         BUG_ON(other < 0);
2717                         pr_debug("Computing stripe %llu blocks %d,%d\n",
2718                                (unsigned long long)sh->sector,
2719                                disk_idx, other);
2720                         set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2721                         set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2722                         set_bit(R5_Wantcompute, &sh->dev[disk_idx].flags);
2723                         set_bit(R5_Wantcompute, &sh->dev[other].flags);
2724                         sh->ops.target = disk_idx;
2725                         sh->ops.target2 = other;
2726                         s->uptodate += 2;
2727                         s->req_compute = 1;
2728                         return 1;
2729                 } else if (test_bit(R5_Insync, &dev->flags)) {
2730                         set_bit(R5_LOCKED, &dev->flags);
2731                         set_bit(R5_Wantread, &dev->flags);
2732                         s->locked++;
2733                         pr_debug("Reading block %d (sync=%d)\n",
2734                                 disk_idx, s->syncing);
2735                 }
2736         }
2737
2738         return 0;
2739 }
2740
2741 /**
2742  * handle_stripe_fill - read or compute data to satisfy pending requests.
2743  */
2744 static void handle_stripe_fill(struct stripe_head *sh,
2745                                struct stripe_head_state *s,
2746                                int disks)
2747 {
2748         int i;
2749
2750         /* look for blocks to read/compute, skip this if a compute
2751          * is already in flight, or if the stripe contents are in the
2752          * midst of changing due to a write
2753          */
2754         if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
2755             !sh->reconstruct_state)
2756                 for (i = disks; i--; )
2757                         if (fetch_block(sh, s, i, disks))
2758                                 break;
2759         set_bit(STRIPE_HANDLE, &sh->state);
2760 }
2761
2762
2763 /* handle_stripe_clean_event
2764  * any written block on an uptodate or failed drive can be returned.
2765  * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
2766  * never LOCKED, so we don't need to test 'failed' directly.
2767  */
2768 static void handle_stripe_clean_event(struct r5conf *conf,
2769         struct stripe_head *sh, int disks, struct bio **return_bi)
2770 {
2771         int i;
2772         struct r5dev *dev;
2773         int discard_pending = 0;
2774
2775         for (i = disks; i--; )
2776                 if (sh->dev[i].written) {
2777                         dev = &sh->dev[i];
2778                         if (!test_bit(R5_LOCKED, &dev->flags) &&
2779                             (test_bit(R5_UPTODATE, &dev->flags) ||
2780                              test_bit(R5_Discard, &dev->flags))) {
2781                                 /* We can return any write requests */
2782                                 struct bio *wbi, *wbi2;
2783                                 pr_debug("Return write for disc %d\n", i);
2784                                 if (test_and_clear_bit(R5_Discard, &dev->flags))
2785                                         clear_bit(R5_UPTODATE, &dev->flags);
2786                                 wbi = dev->written;
2787                                 dev->written = NULL;
2788                                 while (wbi && wbi->bi_sector <
2789                                         dev->sector + STRIPE_SECTORS) {
2790                                         wbi2 = r5_next_bio(wbi, dev->sector);
2791                                         if (!raid5_dec_bi_active_stripes(wbi)) {
2792                                                 md_write_end(conf->mddev);
2793                                                 wbi->bi_next = *return_bi;
2794                                                 *return_bi = wbi;
2795                                         }
2796                                         wbi = wbi2;
2797                                 }
2798                                 bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2799                                                 STRIPE_SECTORS,
2800                                          !test_bit(STRIPE_DEGRADED, &sh->state),
2801                                                 0);
2802                         } else if (test_bit(R5_Discard, &dev->flags))
2803                                 discard_pending = 1;
2804                 }
2805         if (!discard_pending &&
2806             test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
2807                 clear_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
2808                 clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
2809                 if (sh->qd_idx >= 0) {
2810                         clear_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
2811                         clear_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags);
2812                 }
2813                 /* now that discard is done we can proceed with any sync */
2814                 clear_bit(STRIPE_DISCARD, &sh->state);
2815                 /*
2816                  * SCSI discard will change some bio fields and the stripe has
2817                  * no updated data, so remove it from hash list and the stripe
2818                  * will be reinitialized
2819                  */
2820                 spin_lock_irq(&conf->device_lock);
2821                 remove_hash(sh);
2822                 spin_unlock_irq(&conf->device_lock);
2823                 if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state))
2824                         set_bit(STRIPE_HANDLE, &sh->state);
2825
2826         }
2827
2828         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2829                 if (atomic_dec_and_test(&conf->pending_full_writes))
2830                         md_wakeup_thread(conf->mddev->thread);
2831 }
2832
2833 static void handle_stripe_dirtying(struct r5conf *conf,
2834                                    struct stripe_head *sh,
2835                                    struct stripe_head_state *s,
2836                                    int disks)
2837 {
2838         int rmw = 0, rcw = 0, i;
2839         sector_t recovery_cp = conf->mddev->recovery_cp;
2840
2841         /* RAID6 requires 'rcw' in current implementation.
2842          * Otherwise, check whether resync is now happening or should start.
2843          * If yes, then the array is dirty (after unclean shutdown or
2844          * initial creation), so parity in some stripes might be inconsistent.
2845          * In this case, we need to always do reconstruct-write, to ensure
2846          * that in case of drive failure or read-error correction, we
2847          * generate correct data from the parity.
2848          */
2849         if (conf->max_degraded == 2 ||
2850             (recovery_cp < MaxSector && sh->sector >= recovery_cp)) {
2851                 /* Calculate the real rcw later - for now make it
2852                  * look like rcw is cheaper
2853                  */
2854                 rcw = 1; rmw = 2;
2855                 pr_debug("force RCW max_degraded=%u, recovery_cp=%llu sh->sector=%llu\n",
2856                          conf->max_degraded, (unsigned long long)recovery_cp,
2857                          (unsigned long long)sh->sector);
2858         } else for (i = disks; i--; ) {
2859                 /* would I have to read this buffer for read_modify_write */
2860                 struct r5dev *dev = &sh->dev[i];
2861                 if ((dev->towrite || i == sh->pd_idx) &&
2862                     !test_bit(R5_LOCKED, &dev->flags) &&
2863                     !(test_bit(R5_UPTODATE, &dev->flags) ||
2864                       test_bit(R5_Wantcompute, &dev->flags))) {
2865                         if (test_bit(R5_Insync, &dev->flags))
2866                                 rmw++;
2867                         else
2868                                 rmw += 2*disks;  /* cannot read it */
2869                 }
2870                 /* Would I have to read this buffer for reconstruct_write */
2871                 if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
2872                     !test_bit(R5_LOCKED, &dev->flags) &&
2873                     !(test_bit(R5_UPTODATE, &dev->flags) ||
2874                     test_bit(R5_Wantcompute, &dev->flags))) {
2875                         if (test_bit(R5_Insync, &dev->flags)) rcw++;
2876                         else
2877                                 rcw += 2*disks;
2878                 }
2879         }
2880         pr_debug("for sector %llu, rmw=%d rcw=%d\n",
2881                 (unsigned long long)sh->sector, rmw, rcw);
2882         set_bit(STRIPE_HANDLE, &sh->state);
2883         if (rmw < rcw && rmw > 0) {
2884                 /* prefer read-modify-write, but need to get some data */
2885                 if (conf->mddev->queue)
2886                         blk_add_trace_msg(conf->mddev->queue,
2887                                           "raid5 rmw %llu %d",
2888                                           (unsigned long long)sh->sector, rmw);
2889                 for (i = disks; i--; ) {
2890                         struct r5dev *dev = &sh->dev[i];
2891                         if ((dev->towrite || i == sh->pd_idx) &&
2892                             !test_bit(R5_LOCKED, &dev->flags) &&
2893                             !(test_bit(R5_UPTODATE, &dev->flags) ||
2894                             test_bit(R5_Wantcompute, &dev->flags)) &&
2895                             test_bit(R5_Insync, &dev->flags)) {
2896                                 if (
2897                                   test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2898                                         pr_debug("Read_old block "
2899                                                  "%d for r-m-w\n", i);
2900                                         set_bit(R5_LOCKED, &dev->flags);
2901                                         set_bit(R5_Wantread, &dev->flags);
2902                                         s->locked++;
2903                                 } else {
2904                                         set_bit(STRIPE_DELAYED, &sh->state);
2905                                         set_bit(STRIPE_HANDLE, &sh->state);
2906                                 }
2907                         }
2908                 }
2909         }
2910         if (rcw <= rmw && rcw > 0) {
2911                 /* want reconstruct write, but need to get some data */
2912                 int qread =0;
2913                 rcw = 0;
2914                 for (i = disks; i--; ) {
2915                         struct r5dev *dev = &sh->dev[i];
2916                         if (!test_bit(R5_OVERWRITE, &dev->flags) &&
2917                             i != sh->pd_idx && i != sh->qd_idx &&
2918                             !test_bit(R5_LOCKED, &dev->flags) &&
2919                             !(test_bit(R5_UPTODATE, &dev->flags) ||
2920                               test_bit(R5_Wantcompute, &dev->flags))) {
2921                                 rcw++;
2922                                 if (!test_bit(R5_Insync, &dev->flags))
2923                                         continue; /* it's a failed drive */
2924                                 if (
2925                                   test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2926                                         pr_debug("Read_old block "
2927                                                 "%d for Reconstruct\n", i);
2928                                         set_bit(R5_LOCKED, &dev->flags);
2929                                         set_bit(R5_Wantread, &dev->flags);
2930                                         s->locked++;
2931                                         qread++;
2932                                 } else {
2933                                         set_bit(STRIPE_DELAYED, &sh->state);
2934                                         set_bit(STRIPE_HANDLE, &sh->state);
2935                                 }
2936                         }
2937                 }
2938                 if (rcw && conf->mddev->queue)
2939                         blk_add_trace_msg(conf->mddev->queue, "raid5 rcw %llu %d %d %d",
2940                                           (unsigned long long)sh->sector,
2941                                           rcw, qread, test_bit(STRIPE_DELAYED, &sh->state));
2942         }
2943         /* now if nothing is locked, and if we have enough data,
2944          * we can start a write request
2945          */
2946         /* since handle_stripe can be called at any time we need to handle the
2947          * case where a compute block operation has been submitted and then a
2948          * subsequent call wants to start a write request.  raid_run_ops only
2949          * handles the case where compute block and reconstruct are requested
2950          * simultaneously.  If this is not the case then new writes need to be
2951          * held off until the compute completes.
2952          */
2953         if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
2954             (s->locked == 0 && (rcw == 0 || rmw == 0) &&
2955             !test_bit(STRIPE_BIT_DELAY, &sh->state)))
2956                 schedule_reconstruction(sh, s, rcw == 0, 0);
2957 }
2958
2959 static void handle_parity_checks5(struct r5conf *conf, struct stripe_head *sh,
2960                                 struct stripe_head_state *s, int disks)
2961 {
2962         struct r5dev *dev = NULL;
2963
2964         set_bit(STRIPE_HANDLE, &sh->state);
2965
2966         switch (sh->check_state) {
2967         case check_state_idle:
2968                 /* start a new check operation if there are no failures */
2969                 if (s->failed == 0) {
2970                         BUG_ON(s->uptodate != disks);
2971                         sh->check_state = check_state_run;
2972                         set_bit(STRIPE_OP_CHECK, &s->ops_request);
2973                         clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
2974                         s->uptodate--;
2975                         break;
2976                 }
2977                 dev = &sh->dev[s->failed_num[0]];
2978                 /* fall through */
2979         case check_state_compute_result:
2980                 sh->check_state = check_state_idle;
2981                 if (!dev)
2982                         dev = &sh->dev[sh->pd_idx];
2983
2984                 /* check that a write has not made the stripe insync */
2985                 if (test_bit(STRIPE_INSYNC, &sh->state))
2986                         break;
2987
2988                 /* either failed parity check, or recovery is happening */
2989                 BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
2990                 BUG_ON(s->uptodate != disks);
2991
2992                 set_bit(R5_LOCKED, &dev->flags);
2993                 s->locked++;
2994                 set_bit(R5_Wantwrite, &dev->flags);
2995
2996                 clear_bit(STRIPE_DEGRADED, &sh->state);
2997                 set_bit(STRIPE_INSYNC, &sh->state);
2998                 break;
2999         case check_state_run:
3000                 break; /* we will be called again upon completion */
3001         case check_state_check_result:
3002                 sh->check_state = check_state_idle;
3003
3004                 /* if a failure occurred during the check operation, leave
3005                  * STRIPE_INSYNC not set and let the stripe be handled again
3006                  */
3007                 if (s->failed)
3008                         break;
3009
3010                 /* handle a successful check operation, if parity is correct
3011                  * we are done.  Otherwise update the mismatch count and repair
3012                  * parity if !MD_RECOVERY_CHECK
3013                  */
3014                 if ((sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) == 0)
3015                         /* parity is correct (on disc,
3016                          * not in buffer any more)
3017                          */
3018                         set_bit(STRIPE_INSYNC, &sh->state);
3019                 else {
3020                         atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3021                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3022                                 /* don't try to repair!! */
3023                                 set_bit(STRIPE_INSYNC, &sh->state);
3024                         else {
3025                                 sh->check_state = check_state_compute_run;
3026                                 set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3027                                 set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3028                                 set_bit(R5_Wantcompute,
3029                                         &sh->dev[sh->pd_idx].flags);
3030                                 sh->ops.target = sh->pd_idx;
3031                                 sh->ops.target2 = -1;
3032                                 s->uptodate++;
3033                         }
3034                 }
3035                 break;
3036         case check_state_compute_run:
3037                 break;
3038         default:
3039                 printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
3040                        __func__, sh->check_state,
3041                        (unsigned long long) sh->sector);
3042                 BUG();
3043         }
3044 }
3045
3046
3047 static void handle_parity_checks6(struct r5conf *conf, struct stripe_head *sh,
3048                                   struct stripe_head_state *s,
3049                                   int disks)
3050 {
3051         int pd_idx = sh->pd_idx;
3052         int qd_idx = sh->qd_idx;
3053         struct r5dev *dev;
3054
3055         set_bit(STRIPE_HANDLE, &sh->state);
3056
3057         BUG_ON(s->failed > 2);
3058
3059         /* Want to check and possibly repair P and Q.
3060          * However there could be one 'failed' device, in which
3061          * case we can only check one of them, possibly using the
3062          * other to generate missing data
3063          */
3064
3065         switch (sh->check_state) {
3066         case check_state_idle:
3067                 /* start a new check operation if there are < 2 failures */
3068                 if (s->failed == s->q_failed) {
3069                         /* The only possible failed device holds Q, so it
3070                          * makes sense to check P (If anything else were failed,
3071                          * we would have used P to recreate it).
3072                          */
3073                         sh->check_state = check_state_run;
3074                 }
3075                 if (!s->q_failed && s->failed < 2) {
3076                         /* Q is not failed, and we didn't use it to generate
3077                          * anything, so it makes sense to check it
3078                          */
3079                         if (sh->check_state == check_state_run)
3080                                 sh->check_state = check_state_run_pq;
3081                         else
3082                                 sh->check_state = check_state_run_q;
3083                 }
3084
3085                 /* discard potentially stale zero_sum_result */
3086                 sh->ops.zero_sum_result = 0;
3087
3088                 if (sh->check_state == check_state_run) {
3089                         /* async_xor_zero_sum destroys the contents of P */
3090                         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
3091                         s->uptodate--;
3092                 }
3093                 if (sh->check_state >= check_state_run &&
3094                     sh->check_state <= check_state_run_pq) {
3095                         /* async_syndrome_zero_sum preserves P and Q, so
3096                          * no need to mark them !uptodate here
3097                          */
3098                         set_bit(STRIPE_OP_CHECK, &s->ops_request);
3099                         break;
3100                 }
3101
3102                 /* we have 2-disk failure */
3103                 BUG_ON(s->failed != 2);
3104                 /* fall through */
3105         case check_state_compute_result:
3106                 sh->check_state = check_state_idle;
3107
3108                 /* check that a write has not made the stripe insync */
3109                 if (test_bit(STRIPE_INSYNC, &sh->state))
3110                         break;
3111
3112                 /* now write out any block on a failed drive,
3113                  * or P or Q if they were recomputed
3114                  */
3115                 BUG_ON(s->uptodate < disks - 1); /* We don't need Q to recover */
3116                 if (s->failed == 2) {
3117                         dev = &sh->dev[s->failed_num[1]];
3118                         s->locked++;
3119                         set_bit(R5_LOCKED, &dev->flags);
3120                         set_bit(R5_Wantwrite, &dev->flags);
3121                 }
3122                 if (s->failed >= 1) {
3123                         dev = &sh->dev[s->failed_num[0]];
3124                         s->locked++;
3125                         set_bit(R5_LOCKED, &dev->flags);
3126                         set_bit(R5_Wantwrite, &dev->flags);
3127                 }
3128                 if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3129                         dev = &sh->dev[pd_idx];
3130                         s->locked++;
3131                         set_bit(R5_LOCKED, &dev->flags);
3132                         set_bit(R5_Wantwrite, &dev->flags);
3133                 }
3134                 if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3135                         dev = &sh->dev[qd_idx];
3136                         s->locked++;
3137                         set_bit(R5_LOCKED, &dev->flags);
3138                         set_bit(R5_Wantwrite, &dev->flags);
3139                 }
3140                 clear_bit(STRIPE_DEGRADED, &sh->state);
3141
3142                 set_bit(STRIPE_INSYNC, &sh->state);
3143                 break;
3144         case check_state_run:
3145         case check_state_run_q:
3146         case check_state_run_pq:
3147                 break; /* we will be called again upon completion */
3148         case check_state_check_result:
3149                 sh->check_state = check_state_idle;
3150
3151                 /* handle a successful check operation, if parity is correct
3152                  * we are done.  Otherwise update the mismatch count and repair
3153                  * parity if !MD_RECOVERY_CHECK
3154                  */
3155                 if (sh->ops.zero_sum_result == 0) {
3156                         /* both parities are correct */
3157                         if (!s->failed)
3158                                 set_bit(STRIPE_INSYNC, &sh->state);
3159                         else {
3160                                 /* in contrast to the raid5 case we can validate
3161                                  * parity, but still have a failure to write
3162                                  * back
3163                                  */
3164                                 sh->check_state = check_state_compute_result;
3165                                 /* Returning at this point means that we may go
3166                                  * off and bring p and/or q uptodate again so
3167                                  * we make sure to check zero_sum_result again
3168                                  * to verify if p or q need writeback
3169                                  */
3170                         }
3171                 } else {
3172                         atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3173                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3174                                 /* don't try to repair!! */
3175                                 set_bit(STRIPE_INSYNC, &sh->state);
3176                         else {
3177                                 int *target = &sh->ops.target;
3178
3179                                 sh->ops.target = -1;
3180                                 sh->ops.target2 = -1;
3181                                 sh->check_state = check_state_compute_run;
3182                                 set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3183                                 set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3184                                 if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3185                                         set_bit(R5_Wantcompute,
3186                                                 &sh->dev[pd_idx].flags);
3187                                         *target = pd_idx;
3188                                         target = &sh->ops.target2;
3189                                         s->uptodate++;
3190                                 }
3191                                 if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3192                                         set_bit(R5_Wantcompute,
3193                                                 &sh->dev[qd_idx].flags);
3194                                         *target = qd_idx;
3195                                         s->uptodate++;
3196                                 }
3197                         }
3198                 }
3199                 break;
3200         case check_state_compute_run:
3201                 break;
3202         default:
3203                 printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
3204                        __func__, sh->check_state,
3205                        (unsigned long long) sh->sector);
3206                 BUG();
3207         }
3208 }
3209
3210 static void handle_stripe_expansion(struct r5conf *conf, struct stripe_head *sh)
3211 {
3212         int i;
3213
3214         /* We have read all the blocks in this stripe and now we need to
3215          * copy some of them into a target stripe for expand.
3216          */
3217         struct dma_async_tx_descriptor *tx = NULL;
3218         clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3219         for (i = 0; i < sh->disks; i++)
3220                 if (i != sh->pd_idx && i != sh->qd_idx) {
3221                         int dd_idx, j;
3222                         struct stripe_head *sh2;
3223                         struct async_submit_ctl submit;
3224
3225                         sector_t bn = compute_blocknr(sh, i, 1);
3226                         sector_t s = raid5_compute_sector(conf, bn, 0,
3227                                                           &dd_idx, NULL);
3228                         sh2 = get_active_stripe(conf, s, 0, 1, 1);
3229                         if (sh2 == NULL)
3230                                 /* so far only the early blocks of this stripe
3231                                  * have been requested.  When later blocks
3232                                  * get requested, we will try again
3233                                  */
3234                                 continue;
3235                         if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
3236                            test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
3237                                 /* must have already done this block */
3238                                 release_stripe(sh2);
3239                                 continue;
3240                         }
3241
3242                         /* place all the copies on one channel */
3243                         init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
3244                         tx = async_memcpy(sh2->dev[dd_idx].page,
3245                                           sh->dev[i].page, 0, 0, STRIPE_SIZE,
3246                                           &submit);
3247
3248                         set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
3249                         set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
3250                         for (j = 0; j < conf->raid_disks; j++)
3251                                 if (j != sh2->pd_idx &&
3252                                     j != sh2->qd_idx &&
3253                                     !test_bit(R5_Expanded, &sh2->dev[j].flags))
3254                                         break;
3255                         if (j == conf->raid_disks) {
3256                                 set_bit(STRIPE_EXPAND_READY, &sh2->state);
3257                                 set_bit(STRIPE_HANDLE, &sh2->state);
3258                         }
3259                         release_stripe(sh2);
3260
3261                 }
3262         /* done submitting copies, wait for them to complete */
3263         async_tx_quiesce(&tx);
3264 }
3265
3266 /*
3267  * handle_stripe - do things to a stripe.
3268  *
3269  * We lock the stripe by setting STRIPE_ACTIVE and then examine the
3270  * state of various bits to see what needs to be done.
3271  * Possible results:
3272  *    return some read requests which now have data
3273  *    return some write requests which are safely on storage
3274  *    schedule a read on some buffers
3275  *    schedule a write of some buffers
3276  *    return confirmation of parity correctness
3277  *
3278  */
3279
3280 static void analyse_stripe(struct stripe_head *sh, struct stripe_head_state *s)
3281 {
3282         struct r5conf *conf = sh->raid_conf;
3283         int disks = sh->disks;
3284         struct r5dev *dev;
3285         int i;
3286         int do_recovery = 0;
3287
3288         memset(s, 0, sizeof(*s));
3289
3290         s->expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3291         s->expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
3292         s->failed_num[0] = -1;
3293         s->failed_num[1] = -1;
3294
3295         /* Now to look around and see what can be done */
3296         rcu_read_lock();
3297         for (i=disks; i--; ) {
3298                 struct md_rdev *rdev;
3299                 sector_t first_bad;
3300                 int bad_sectors;
3301                 int is_bad = 0;
3302
3303                 dev = &sh->dev[i];
3304
3305                 pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
3306                          i, dev->flags,
3307                          dev->toread, dev->towrite, dev->written);
3308                 /* maybe we can reply to a read
3309                  *
3310                  * new wantfill requests are only permitted while
3311                  * ops_complete_biofill is guaranteed to be inactive
3312                  */
3313                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
3314                     !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
3315                         set_bit(R5_Wantfill, &dev->flags);
3316
3317                 /* now count some things */
3318                 if (test_bit(R5_LOCKED, &dev->flags))
3319                         s->locked++;
3320                 if (test_bit(R5_UPTODATE, &dev->flags))
3321                         s->uptodate++;
3322                 if (test_bit(R5_Wantcompute, &dev->flags)) {
3323                         s->compute++;
3324                         BUG_ON(s->compute > 2);
3325                 }
3326
3327                 if (test_bit(R5_Wantfill, &dev->flags))
3328                         s->to_fill++;
3329                 else if (dev->toread)
3330                         s->to_read++;
3331                 if (dev->towrite) {
3332                         s->to_write++;
3333                         if (!test_bit(R5_OVERWRITE, &dev->flags))
3334                                 s->non_overwrite++;
3335                 }
3336                 if (dev->written)
3337                         s->written++;
3338                 /* Prefer to use the replacement for reads, but only
3339                  * if it is recovered enough and has no bad blocks.
3340                  */
3341                 rdev = rcu_dereference(conf->disks[i].replacement);
3342                 if (rdev && !test_bit(Faulty, &rdev->flags) &&
3343                     rdev->recovery_offset >= sh->sector + STRIPE_SECTORS &&
3344                     !is_badblock(rdev, sh->sector, STRIPE_SECTORS,
3345                                  &first_bad, &bad_sectors))
3346                         set_bit(R5_ReadRepl, &dev->flags);
3347                 else {
3348                         if (rdev)
3349                                 set_bit(R5_NeedReplace, &dev->flags);
3350                         rdev = rcu_dereference(conf->disks[i].rdev);
3351                         clear_bit(R5_ReadRepl, &dev->flags);
3352                 }
3353                 if (rdev && test_bit(Faulty, &rdev->flags))
3354                         rdev = NULL;
3355                 if (rdev) {
3356                         is_bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
3357                                              &first_bad, &bad_sectors);
3358                         if (s->blocked_rdev == NULL
3359                             && (test_bit(Blocked, &rdev->flags)
3360                                 || is_bad < 0)) {
3361                                 if (is_bad < 0)
3362                                         set_bit(BlockedBadBlocks,
3363                                                 &rdev->flags);
3364                                 s->blocked_rdev = rdev;
3365                                 atomic_inc(&rdev->nr_pending);
3366                         }
3367                 }
3368                 clear_bit(R5_Insync, &dev->flags);
3369                 if (!rdev)
3370                         /* Not in-sync */;
3371                 else if (is_bad) {
3372                         /* also not in-sync */
3373                         if (!test_bit(WriteErrorSeen, &rdev->flags) &&
3374                             test_bit(R5_UPTODATE, &dev->flags)) {
3375                                 /* treat as in-sync, but with a read error
3376                                  * which we can now try to correct
3377                                  */
3378                                 set_bit(R5_Insync, &dev->flags);
3379                                 set_bit(R5_ReadError, &dev->flags);
3380                         }
3381                 } else if (test_bit(In_sync, &rdev->flags))
3382                         set_bit(R5_Insync, &dev->flags);
3383                 else if (sh->sector + STRIPE_SECTORS <= rdev->recovery_offset)
3384                         /* in sync if before recovery_offset */
3385                         set_bit(R5_Insync, &dev->flags);
3386                 else if (test_bit(R5_UPTODATE, &dev->flags) &&
3387                          test_bit(R5_Expanded, &dev->flags))
3388                         /* If we've reshaped into here, we assume it is Insync.
3389                          * We will shortly update recovery_offset to make
3390                          * it official.
3391                          */
3392                         set_bit(R5_Insync, &dev->flags);
3393
3394                 if (rdev && test_bit(R5_WriteError, &dev->flags)) {
3395                         /* This flag does not apply to '.replacement'
3396                          * only to .rdev, so make sure to check that*/
3397                         struct md_rdev *rdev2 = rcu_dereference(
3398                                 conf->disks[i].rdev);
3399                         if (rdev2 == rdev)
3400                                 clear_bit(R5_Insync, &dev->flags);
3401                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3402                                 s->handle_bad_blocks = 1;
3403                                 atomic_inc(&rdev2->nr_pending);
3404                         } else
3405                                 clear_bit(R5_WriteError, &dev->flags);
3406                 }
3407                 if (rdev && test_bit(R5_MadeGood, &dev->flags)) {
3408                         /* This flag does not apply to '.replacement'
3409                          * only to .rdev, so make sure to check that*/
3410                         struct md_rdev *rdev2 = rcu_dereference(
3411                                 conf->disks[i].rdev);
3412                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3413                                 s->handle_bad_blocks = 1;
3414                                 atomic_inc(&rdev2->nr_pending);
3415                         } else
3416                                 clear_bit(R5_MadeGood, &dev->flags);
3417                 }
3418                 if (test_bit(R5_MadeGoodRepl, &dev->flags)) {
3419                         struct md_rdev *rdev2 = rcu_dereference(
3420                                 conf->disks[i].replacement);
3421                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3422                                 s->handle_bad_blocks = 1;
3423                                 atomic_inc(&rdev2->nr_pending);
3424                         } else
3425                                 clear_bit(R5_MadeGoodRepl, &dev->flags);
3426                 }
3427                 if (!test_bit(R5_Insync, &dev->flags)) {
3428                         /* The ReadError flag will just be confusing now */
3429                         clear_bit(R5_ReadError, &dev->flags);
3430                         clear_bit(R5_ReWrite, &dev->flags);
3431                 }
3432                 if (test_bit(R5_ReadError, &dev->flags))
3433                         clear_bit(R5_Insync, &dev->flags);
3434                 if (!test_bit(R5_Insync, &dev->flags)) {
3435                         if (s->failed < 2)
3436                                 s->failed_num[s->failed] = i;
3437                         s->failed++;
3438                         if (rdev && !test_bit(Faulty, &rdev->flags))
3439                                 do_recovery = 1;
3440                 }
3441         }
3442         if (test_bit(STRIPE_SYNCING, &sh->state)) {
3443                 /* If there is a failed device being replaced,
3444                  *     we must be recovering.
3445                  * else if we are after recovery_cp, we must be syncing
3446                  * else if MD_RECOVERY_REQUESTED is set, we also are syncing.
3447                  * else we can only be replacing
3448                  * sync and recovery both need to read all devices, and so
3449                  * use the same flag.
3450                  */
3451                 if (do_recovery ||
3452                     sh->sector >= conf->mddev->recovery_cp ||
3453                     test_bit(MD_RECOVERY_REQUESTED, &(conf->mddev->recovery)))
3454                         s->syncing = 1;
3455                 else
3456                         s->replacing = 1;
3457         }
3458         rcu_read_unlock();
3459 }
3460
3461 static void handle_stripe(struct stripe_head *sh)
3462 {
3463         struct stripe_head_state s;
3464         struct r5conf *conf = sh->raid_conf;
3465         int i;
3466         int prexor;
3467         int disks = sh->disks;
3468         struct r5dev *pdev, *qdev;
3469
3470         clear_bit(STRIPE_HANDLE, &sh->state);
3471         if (test_and_set_bit_lock(STRIPE_ACTIVE, &sh->state)) {
3472                 /* already being handled, ensure it gets handled
3473                  * again when current action finishes */
3474                 set_bit(STRIPE_HANDLE, &sh->state);
3475                 return;
3476         }
3477
3478         if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
3479                 spin_lock(&sh->stripe_lock);
3480                 /* Cannot process 'sync' concurrently with 'discard' */
3481                 if (!test_bit(STRIPE_DISCARD, &sh->state) &&
3482                     test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
3483                         set_bit(STRIPE_SYNCING, &sh->state);
3484                         clear_bit(STRIPE_INSYNC, &sh->state);
3485                         clear_bit(STRIPE_REPLACED, &sh->state);
3486                 }
3487                 spin_unlock(&sh->stripe_lock);
3488         }
3489         clear_bit(STRIPE_DELAYED, &sh->state);
3490
3491         pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
3492                 "pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
3493                (unsigned long long)sh->sector, sh->state,
3494                atomic_read(&sh->count), sh->pd_idx, sh->qd_idx,
3495                sh->check_state, sh->reconstruct_state);
3496
3497         analyse_stripe(sh, &s);
3498
3499         if (s.handle_bad_blocks) {
3500                 set_bit(STRIPE_HANDLE, &sh->state);
3501                 goto finish;
3502         }
3503
3504         if (unlikely(s.blocked_rdev)) {
3505                 if (s.syncing || s.expanding || s.expanded ||
3506                     s.replacing || s.to_write || s.written) {
3507                         set_bit(STRIPE_HANDLE, &sh->state);
3508                         goto finish;
3509                 }
3510                 /* There is nothing for the blocked_rdev to block */
3511                 rdev_dec_pending(s.blocked_rdev, conf->mddev);
3512                 s.blocked_rdev = NULL;
3513         }
3514
3515         if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
3516                 set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
3517                 set_bit(STRIPE_BIOFILL_RUN, &sh->state);
3518         }
3519
3520         pr_debug("locked=%d uptodate=%d to_read=%d"
3521                " to_write=%d failed=%d failed_num=%d,%d\n",
3522                s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
3523                s.failed_num[0], s.failed_num[1]);
3524         /* check if the array has lost more than max_degraded devices and,
3525          * if so, some requests might need to be failed.
3526          */
3527         if (s.failed > conf->max_degraded) {
3528                 sh->check_state = 0;
3529                 sh->reconstruct_state = 0;
3530                 if (s.to_read+s.to_write+s.written)
3531                         handle_failed_stripe(conf, sh, &s, disks, &s.return_bi);
3532                 if (s.syncing + s.replacing)
3533                         handle_failed_sync(conf, sh, &s);
3534         }
3535
3536         /* Now we check to see if any write operations have recently
3537          * completed
3538          */
3539         prexor = 0;
3540         if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
3541                 prexor = 1;
3542         if (sh->reconstruct_state == reconstruct_state_drain_result ||
3543             sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
3544                 sh->reconstruct_state = reconstruct_state_idle;
3545
3546                 /* All the 'written' buffers and the parity block are ready to
3547                  * be written back to disk
3548                  */
3549                 BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags) &&
3550                        !test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags));
3551                 BUG_ON(sh->qd_idx >= 0 &&
3552                        !test_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags) &&
3553                        !test_bit(R5_Discard, &sh->dev[sh->qd_idx].flags));
3554                 for (i = disks; i--; ) {
3555                         struct r5dev *dev = &sh->dev[i];
3556                         if (test_bit(R5_LOCKED, &dev->flags) &&
3557                                 (i == sh->pd_idx || i == sh->qd_idx ||
3558                                  dev->written)) {
3559                                 pr_debug("Writing block %d\n", i);
3560                                 set_bit(R5_Wantwrite, &dev->flags);
3561                                 if (prexor)
3562                                         continue;
3563                                 if (!test_bit(R5_Insync, &dev->flags) ||
3564                                     ((i == sh->pd_idx || i == sh->qd_idx)  &&
3565                                      s.failed == 0))
3566                                         set_bit(STRIPE_INSYNC, &sh->state);
3567                         }
3568                 }
3569                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3570                         s.dec_preread_active = 1;
3571         }
3572
3573         /*
3574          * might be able to return some write requests if the parity blocks
3575          * are safe, or on a failed drive
3576          */
3577         pdev = &sh->dev[sh->pd_idx];
3578         s.p_failed = (s.failed >= 1 && s.failed_num[0] == sh->pd_idx)
3579                 || (s.failed >= 2 && s.failed_num[1] == sh->pd_idx);
3580         qdev = &sh->dev[sh->qd_idx];
3581         s.q_failed = (s.failed >= 1 && s.failed_num[0] == sh->qd_idx)
3582                 || (s.failed >= 2 && s.failed_num[1] == sh->qd_idx)
3583                 || conf->level < 6;
3584
3585         if (s.written &&
3586             (s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
3587                              && !test_bit(R5_LOCKED, &pdev->flags)
3588                              && (test_bit(R5_UPTODATE, &pdev->flags) ||
3589                                  test_bit(R5_Discard, &pdev->flags))))) &&
3590             (s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
3591                              && !test_bit(R5_LOCKED, &qdev->flags)
3592                              && (test_bit(R5_UPTODATE, &qdev->flags) ||
3593                                  test_bit(R5_Discard, &qdev->flags))))))
3594                 handle_stripe_clean_event(conf, sh, disks, &s.return_bi);
3595
3596         /* Now we might consider reading some blocks, either to check/generate
3597          * parity, or to satisfy requests
3598          * or to load a block that is being partially written.
3599          */
3600         if (s.to_read || s.non_overwrite
3601             || (conf->level == 6 && s.to_write && s.failed)
3602             || (s.syncing && (s.uptodate + s.compute < disks))
3603             || s.replacing
3604             || s.expanding)
3605                 handle_stripe_fill(sh, &s, disks);
3606
3607         /* Now to consider new write requests and what else, if anything
3608          * should be read.  We do not handle new writes when:
3609          * 1/ A 'write' operation (copy+xor) is already in flight.
3610          * 2/ A 'check' operation is in flight, as it may clobber the parity
3611          *    block.
3612          */
3613         if (s.to_write && !sh->reconstruct_state && !sh->check_state)
3614                 handle_stripe_dirtying(conf, sh, &s, disks);
3615
3616         /* maybe we need to check and possibly fix the parity for this stripe
3617          * Any reads will already have been scheduled, so we just see if enough
3618          * data is available.  The parity check is held off while parity
3619          * dependent operations are in flight.
3620          */
3621         if (sh->check_state ||
3622             (s.syncing && s.locked == 0 &&
3623              !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
3624              !test_bit(STRIPE_INSYNC, &sh->state))) {
3625                 if (conf->level == 6)
3626                         handle_parity_checks6(conf, sh, &s, disks);
3627                 else
3628                         handle_parity_checks5(conf, sh, &s, disks);
3629         }
3630
3631         if ((s.replacing || s.syncing) && s.locked == 0
3632             && !test_bit(STRIPE_COMPUTE_RUN, &sh->state)
3633             && !test_bit(STRIPE_REPLACED, &sh->state)) {
3634                 /* Write out to replacement devices where possible */
3635                 for (i = 0; i < conf->raid_disks; i++)
3636                         if (test_bit(R5_NeedReplace, &sh->dev[i].flags)) {
3637                                 WARN_ON(!test_bit(R5_UPTODATE, &sh->dev[i].flags));
3638                                 set_bit(R5_WantReplace, &sh->dev[i].flags);
3639                                 set_bit(R5_LOCKED, &sh->dev[i].flags);
3640                                 s.locked++;
3641                         }
3642                 if (s.replacing)
3643                         set_bit(STRIPE_INSYNC, &sh->state);
3644                 set_bit(STRIPE_REPLACED, &sh->state);
3645         }
3646         if ((s.syncing || s.replacing) && s.locked == 0 &&
3647             !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
3648             test_bit(STRIPE_INSYNC, &sh->state)) {
3649                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3650                 clear_bit(STRIPE_SYNCING, &sh->state);
3651                 if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
3652                         wake_up(&conf->wait_for_overlap);
3653         }
3654
3655         /* If the failed drives are just a ReadError, then we might need
3656          * to progress the repair/check process
3657          */
3658         if (s.failed <= conf->max_degraded && !conf->mddev->ro)
3659                 for (i = 0; i < s.failed; i++) {
3660                         struct r5dev *dev = &sh->dev[s.failed_num[i]];
3661                         if (test_bit(R5_ReadError, &dev->flags)
3662                             && !test_bit(R5_LOCKED, &dev->flags)
3663                             && test_bit(R5_UPTODATE, &dev->flags)
3664                                 ) {
3665                                 if (!test_bit(R5_ReWrite, &dev->flags)) {
3666                                         set_bit(R5_Wantwrite, &dev->flags);
3667                                         set_bit(R5_ReWrite, &dev->flags);
3668                                         set_bit(R5_LOCKED, &dev->flags);
3669                                         s.locked++;
3670                                 } else {
3671                                         /* let's read it back */
3672                                         set_bit(R5_Wantread, &dev->flags);
3673                                         set_bit(R5_LOCKED, &dev->flags);
3674                                         s.locked++;
3675                                 }
3676                         }
3677                 }
3678
3679
3680         /* Finish reconstruct operations initiated by the expansion process */
3681         if (sh->reconstruct_state == reconstruct_state_result) {
3682                 struct stripe_head *sh_src
3683                         = get_active_stripe(conf, sh->sector, 1, 1, 1);
3684                 if (sh_src && test_bit(STRIPE_EXPAND_SOURCE, &sh_src->state)) {
3685                         /* sh cannot be written until sh_src has been read.
3686                          * so arrange for sh to be delayed a little
3687                          */
3688                         set_bit(STRIPE_DELAYED, &sh->state);
3689                         set_bit(STRIPE_HANDLE, &sh->state);
3690                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE,
3691                                               &sh_src->state))
3692                                 atomic_inc(&conf->preread_active_stripes);
3693                         release_stripe(sh_src);
3694                         goto finish;
3695                 }
3696                 if (sh_src)
3697                         release_stripe(sh_src);
3698
3699                 sh->reconstruct_state = reconstruct_state_idle;
3700                 clear_bit(STRIPE_EXPANDING, &sh->state);
3701                 for (i = conf->raid_disks; i--; ) {
3702                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
3703                         set_bit(R5_LOCKED, &sh->dev[i].flags);
3704                         s.locked++;
3705                 }
3706         }
3707
3708         if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
3709             !sh->reconstruct_state) {
3710                 /* Need to write out all blocks after computing parity */
3711                 sh->disks = conf->raid_disks;
3712                 stripe_set_idx(sh->sector, conf, 0, sh);
3713                 schedule_reconstruction(sh, &s, 1, 1);
3714         } else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
3715                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
3716                 atomic_dec(&conf->reshape_stripes);
3717                 wake_up(&conf->wait_for_overlap);
3718                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3719         }
3720
3721         if (s.expanding && s.locked == 0 &&
3722             !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
3723                 handle_stripe_expansion(conf, sh);
3724
3725 finish:
3726         /* wait for this device to become unblocked */
3727         if (unlikely(s.blocked_rdev)) {
3728                 if (conf->mddev->external)
3729                         md_wait_for_blocked_rdev(s.blocked_rdev,
3730                                                  conf->mddev);
3731                 else
3732                         /* Internal metadata will immediately
3733                          * be written by raid5d, so we don't
3734                          * need to wait here.
3735                          */
3736                         rdev_dec_pending(s.blocked_rdev,
3737                                          conf->mddev);
3738         }
3739
3740         if (s.handle_bad_blocks)
3741                 for (i = disks; i--; ) {
3742                         struct md_rdev *rdev;
3743                         struct r5dev *dev = &sh->dev[i];
3744                         if (test_and_clear_bit(R5_WriteError, &dev->flags)) {
3745                                 /* We own a safe reference to the rdev */
3746                                 rdev = conf->disks[i].rdev;
3747                                 if (!rdev_set_badblocks(rdev, sh->sector,
3748                                                         STRIPE_SECTORS, 0))
3749                                         md_error(conf->mddev, rdev);
3750                                 rdev_dec_pending(rdev, conf->mddev);
3751                         }
3752                         if (test_and_clear_bit(R5_MadeGood, &dev->flags)) {
3753                                 rdev = conf->disks[i].rdev;
3754                                 rdev_clear_badblocks(rdev, sh->sector,
3755                                                      STRIPE_SECTORS, 0);
3756                                 rdev_dec_pending(rdev, conf->mddev);
3757                         }
3758                         if (test_and_clear_bit(R5_MadeGoodRepl, &dev->flags)) {
3759                                 rdev = conf->disks[i].replacement;
3760                                 if (!rdev)
3761                                         /* rdev have been moved down */
3762                                         rdev = conf->disks[i].rdev;
3763                                 rdev_clear_badblocks(rdev, sh->sector,
3764                                                      STRIPE_SECTORS, 0);
3765                                 rdev_dec_pending(rdev, conf->mddev);
3766                         }
3767                 }
3768
3769         if (s.ops_request)
3770                 raid_run_ops(sh, s.ops_request);
3771
3772         ops_run_io(sh, &s);
3773
3774         if (s.dec_preread_active) {
3775                 /* We delay this until after ops_run_io so that if make_request
3776                  * is waiting on a flush, it won't continue until the writes
3777                  * have actually been submitted.
3778                  */
3779                 atomic_dec(&conf->preread_active_stripes);
3780                 if (atomic_read(&conf->preread_active_stripes) <
3781                     IO_THRESHOLD)
3782                         md_wakeup_thread(conf->mddev->thread);
3783         }
3784
3785         return_io(s.return_bi);
3786
3787         clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
3788 }
3789
3790 static void raid5_activate_delayed(struct r5conf *conf)
3791 {
3792         if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
3793                 while (!list_empty(&conf->delayed_list)) {
3794                         struct list_head *l = conf->delayed_list.next;
3795                         struct stripe_head *sh;
3796                         sh = list_entry(l, struct stripe_head, lru);
3797                         list_del_init(l);
3798                         clear_bit(STRIPE_DELAYED, &sh->state);
3799                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3800                                 atomic_inc(&conf->preread_active_stripes);
3801                         list_add_tail(&sh->lru, &conf->hold_list);
3802                 }
3803         }
3804 }
3805
3806 static void activate_bit_delay(struct r5conf *conf)
3807 {
3808         /* device_lock is held */
3809         struct list_head head;
3810         list_add(&head, &conf->bitmap_list);
3811         list_del_init(&conf->bitmap_list);
3812         while (!list_empty(&head)) {
3813                 struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
3814                 list_del_init(&sh->lru);
3815                 atomic_inc(&sh->count);
3816                 __release_stripe(conf, sh);
3817         }
3818 }
3819
3820 int md_raid5_congested(struct mddev *mddev, int bits)
3821 {
3822         struct r5conf *conf = mddev->private;
3823
3824         /* No difference between reads and writes.  Just check
3825          * how busy the stripe_cache is
3826          */
3827
3828         if (conf->inactive_blocked)
3829                 return 1;
3830         if (conf->quiesce)
3831                 return 1;
3832         if (list_empty_careful(&conf->inactive_list))
3833                 return 1;
3834
3835         return 0;
3836 }
3837 EXPORT_SYMBOL_GPL(md_raid5_congested);
3838
3839 static int raid5_congested(void *data, int bits)
3840 {
3841         struct mddev *mddev = data;
3842
3843         return mddev_congested(mddev, bits) ||
3844                 md_raid5_congested(mddev, bits);
3845 }
3846
3847 /* We want read requests to align with chunks where possible,
3848  * but write requests don't need to.
3849  */
3850 static int raid5_mergeable_bvec(struct request_queue *q,
3851                                 struct bvec_merge_data *bvm,
3852                                 struct bio_vec *biovec)
3853 {
3854         struct mddev *mddev = q->queuedata;
3855         sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
3856         int max;
3857         unsigned int chunk_sectors = mddev->chunk_sectors;
3858         unsigned int bio_sectors = bvm->bi_size >> 9;
3859
3860         if ((bvm->bi_rw & 1) == WRITE)
3861                 return biovec->bv_len; /* always allow writes to be mergeable */
3862
3863         if (mddev->new_chunk_sectors < mddev->chunk_sectors)
3864                 chunk_sectors = mddev->new_chunk_sectors;
3865         max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
3866         if (max < 0) max = 0;
3867         if (max <= biovec->bv_len && bio_sectors == 0)
3868                 return biovec->bv_len;
3869         else
3870                 return max;
3871 }
3872
3873
3874 static int in_chunk_boundary(struct mddev *mddev, struct bio *bio)
3875 {
3876         sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
3877         unsigned int chunk_sectors = mddev->chunk_sectors;
3878         unsigned int bio_sectors = bio_sectors(bio);
3879
3880         if (mddev->new_chunk_sectors < mddev->chunk_sectors)
3881                 chunk_sectors = mddev->new_chunk_sectors;
3882         return  chunk_sectors >=
3883                 ((sector & (chunk_sectors - 1)) + bio_sectors);
3884 }
3885
3886 /*
3887  *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
3888  *  later sampled by raid5d.
3889  */
3890 static void add_bio_to_retry(struct bio *bi,struct r5conf *conf)
3891 {
3892         unsigned long flags;
3893
3894         spin_lock_irqsave(&conf->device_lock, flags);
3895
3896         bi->bi_next = conf->retry_read_aligned_list;
3897         conf->retry_read_aligned_list = bi;
3898
3899         spin_unlock_irqrestore(&conf->device_lock, flags);
3900         md_wakeup_thread(conf->mddev->thread);
3901 }
3902
3903
3904 static struct bio *remove_bio_from_retry(struct r5conf *conf)
3905 {
3906         struct bio *bi;
3907
3908         bi = conf->retry_read_aligned;
3909         if (bi) {
3910                 conf->retry_read_aligned = NULL;
3911                 return bi;
3912         }
3913         bi = conf->retry_read_aligned_list;
3914         if(bi) {
3915                 conf->retry_read_aligned_list = bi->bi_next;
3916                 bi->bi_next = NULL;
3917                 /*
3918                  * this sets the active strip count to 1 and the processed
3919                  * strip count to zero (upper 8 bits)
3920                  */
3921                 raid5_set_bi_stripes(bi, 1); /* biased count of active stripes */
3922         }
3923
3924         return bi;
3925 }
3926
3927
3928 /*
3929  *  The "raid5_align_endio" should check if the read succeeded and if it
3930  *  did, call bio_endio on the original bio (having bio_put the new bio
3931  *  first).
3932  *  If the read failed..
3933  */
3934 static void raid5_align_endio(struct bio *bi, int error)
3935 {
3936         struct bio* raid_bi  = bi->bi_private;
3937         struct mddev *mddev;
3938         struct r5conf *conf;
3939         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
3940         struct md_rdev *rdev;
3941
3942         bio_put(bi);
3943
3944         rdev = (void*)raid_bi->bi_next;
3945         raid_bi->bi_next = NULL;
3946         mddev = rdev->mddev;
3947         conf = mddev->private;
3948
3949         rdev_dec_pending(rdev, conf->mddev);
3950
3951         if (!error && uptodate) {
3952                 trace_block_bio_complete(bdev_get_queue(raid_bi->bi_bdev),
3953                                          raid_bi, 0);
3954                 bio_endio(raid_bi, 0);
3955                 if (atomic_dec_and_test(&conf->active_aligned_reads))
3956                         wake_up(&conf->wait_for_stripe);
3957                 return;
3958         }
3959
3960
3961         pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
3962
3963         add_bio_to_retry(raid_bi, conf);
3964 }
3965
3966 static int bio_fits_rdev(struct bio *bi)
3967 {
3968         struct request_queue *q = bdev_get_queue(bi->bi_bdev);
3969
3970         if (bio_sectors(bi) > queue_max_sectors(q))
3971                 return 0;
3972         blk_recount_segments(q, bi);
3973         if (bi->bi_phys_segments > queue_max_segments(q))
3974                 return 0;
3975
3976         if (q->merge_bvec_fn)
3977                 /* it's too hard to apply the merge_bvec_fn at this stage,
3978                  * just just give up
3979                  */
3980                 return 0;
3981
3982         return 1;
3983 }
3984
3985
3986 static int chunk_aligned_read(struct mddev *mddev, struct bio * raid_bio)
3987 {
3988         struct r5conf *conf = mddev->private;
3989         int dd_idx;
3990         struct bio* align_bi;
3991         struct md_rdev *rdev;
3992         sector_t end_sector;
3993
3994         if (!in_chunk_boundary(mddev, raid_bio)) {
3995                 pr_debug("chunk_aligned_read : non aligned\n");
3996                 return 0;
3997         }
3998         /*
3999          * use bio_clone_mddev to make a copy of the bio
4000          */
4001         align_bi = bio_clone_mddev(raid_bio, GFP_NOIO, mddev);
4002         if (!align_bi)
4003                 return 0;
4004         /*
4005          *   set bi_end_io to a new function, and set bi_private to the
4006          *     original bio.
4007          */
4008         align_bi->bi_end_io  = raid5_align_endio;
4009         align_bi->bi_private = raid_bio;
4010         /*
4011          *      compute position
4012          */
4013         align_bi->bi_sector =  raid5_compute_sector(conf, raid_bio->bi_sector,
4014                                                     0,
4015                                                     &dd_idx, NULL);
4016
4017         end_sector = bio_end_sector(align_bi);
4018         rcu_read_lock();
4019         rdev = rcu_dereference(conf->disks[dd_idx].replacement);
4020         if (!rdev || test_bit(Faulty, &rdev->flags) ||
4021             rdev->recovery_offset < end_sector) {
4022                 rdev = rcu_dereference(conf->disks[dd_idx].rdev);
4023                 if (rdev &&
4024                     (test_bit(Faulty, &rdev->flags) ||
4025                     !(test_bit(In_sync, &rdev->flags) ||
4026                       rdev->recovery_offset >= end_sector)))
4027                         rdev = NULL;
4028         }
4029         if (rdev) {
4030                 sector_t first_bad;
4031                 int bad_sectors;
4032
4033                 atomic_inc(&rdev->nr_pending);
4034                 rcu_read_unlock();
4035                 raid_bio->bi_next = (void*)rdev;
4036                 align_bi->bi_bdev =  rdev->bdev;
4037                 align_bi->bi_flags &= ~(1 << BIO_SEG_VALID);
4038
4039                 if (!bio_fits_rdev(align_bi) ||
4040                     is_badblock(rdev, align_bi->bi_sector, bio_sectors(align_bi),
4041                                 &first_bad, &bad_sectors)) {
4042                         /* too big in some way, or has a known bad block */
4043                         bio_put(align_bi);
4044                         rdev_dec_pending(rdev, mddev);
4045                         return 0;
4046                 }
4047
4048                 /* No reshape active, so we can trust rdev->data_offset */
4049                 align_bi->bi_sector += rdev->data_offset;
4050
4051                 spin_lock_irq(&conf->device_lock);
4052                 wait_event_lock_irq(conf->wait_for_stripe,
4053                                     conf->quiesce == 0,
4054                                     conf->device_lock);
4055                 atomic_inc(&conf->active_aligned_reads);
4056                 spin_unlock_irq(&conf->device_lock);
4057
4058                 if (mddev->gendisk)
4059                         trace_block_bio_remap(bdev_get_queue(align_bi->bi_bdev),
4060                                               align_bi, disk_devt(mddev->gendisk),
4061                                               raid_bio->bi_sector);
4062                 generic_make_request(align_bi);
4063                 return 1;
4064         } else {
4065                 rcu_read_unlock();
4066                 bio_put(align_bi);
4067                 return 0;
4068         }
4069 }
4070
4071 /* __get_priority_stripe - get the next stripe to process
4072  *
4073  * Full stripe writes are allowed to pass preread active stripes up until
4074  * the bypass_threshold is exceeded.  In general the bypass_count
4075  * increments when the handle_list is handled before the hold_list; however, it
4076  * will not be incremented when STRIPE_IO_STARTED is sampled set signifying a
4077  * stripe with in flight i/o.  The bypass_count will be reset when the
4078  * head of the hold_list has changed, i.e. the head was promoted to the
4079  * handle_list.
4080  */
4081 static struct stripe_head *__get_priority_stripe(struct r5conf *conf)
4082 {
4083         struct stripe_head *sh;
4084
4085         pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
4086                   __func__,
4087                   list_empty(&conf->handle_list) ? "empty" : "busy",
4088                   list_empty(&conf->hold_list) ? "empty" : "busy",
4089                   atomic_read(&conf->pending_full_writes), conf->bypass_count);
4090
4091         if (!list_empty(&conf->handle_list)) {
4092                 sh = list_entry(conf->handle_list.next, typeof(*sh), lru);
4093
4094                 if (list_empty(&conf->hold_list))
4095                         conf->bypass_count = 0;
4096                 else if (!test_bit(STRIPE_IO_STARTED, &sh->state)) {
4097                         if (conf->hold_list.next == conf->last_hold)
4098                                 conf->bypass_count++;
4099                         else {
4100                                 conf->last_hold = conf->hold_list.next;
4101                                 conf->bypass_count -= conf->bypass_threshold;
4102                                 if (conf->bypass_count < 0)
4103                                         conf->bypass_count = 0;
4104                         }
4105                 }
4106         } else if (!list_empty(&conf->hold_list) &&
4107                    ((conf->bypass_threshold &&
4108                      conf->bypass_count > conf->bypass_threshold) ||
4109                     atomic_read(&conf->pending_full_writes) == 0)) {
4110                 sh = list_entry(conf->hold_list.next,
4111                                 typeof(*sh), lru);
4112                 conf->bypass_count -= conf->bypass_threshold;
4113                 if (conf->bypass_count < 0)
4114                         conf->bypass_count = 0;
4115         } else
4116                 return NULL;
4117
4118         list_del_init(&sh->lru);
4119         atomic_inc(&sh->count);
4120         BUG_ON(atomic_read(&sh->count) != 1);
4121         return sh;
4122 }
4123
4124 struct raid5_plug_cb {
4125         struct blk_plug_cb      cb;
4126         struct list_head        list;
4127 };
4128
4129 static void raid5_unplug(struct blk_plug_cb *blk_cb, bool from_schedule)
4130 {
4131         struct raid5_plug_cb *cb = container_of(
4132                 blk_cb, struct raid5_plug_cb, cb);
4133         struct stripe_head *sh;
4134         struct mddev *mddev = cb->cb.data;
4135         struct r5conf *conf = mddev->private;
4136         int cnt = 0;
4137
4138         if (cb->list.next && !list_empty(&cb->list)) {
4139                 spin_lock_irq(&conf->device_lock);
4140                 while (!list_empty(&cb->list)) {
4141                         sh = list_first_entry(&cb->list, struct stripe_head, lru);
4142                         list_del_init(&sh->lru);
4143                         /*
4144                          * avoid race release_stripe_plug() sees
4145                          * STRIPE_ON_UNPLUG_LIST clear but the stripe
4146                          * is still in our list
4147                          */
4148                         smp_mb__before_clear_bit();
4149                         clear_bit(STRIPE_ON_UNPLUG_LIST, &sh->state);
4150                         __release_stripe(conf, sh);
4151                         cnt++;
4152                 }
4153                 spin_unlock_irq(&conf->device_lock);
4154         }
4155         if (mddev->queue)
4156                 trace_block_unplug(mddev->queue, cnt, !from_schedule);
4157         kfree(cb);
4158 }
4159
4160 static void release_stripe_plug(struct mddev *mddev,
4161                                 struct stripe_head *sh)
4162 {
4163         struct blk_plug_cb *blk_cb = blk_check_plugged(
4164                 raid5_unplug, mddev,
4165                 sizeof(struct raid5_plug_cb));
4166         struct raid5_plug_cb *cb;
4167
4168         if (!blk_cb) {
4169                 release_stripe(sh);
4170                 return;
4171         }
4172
4173         cb = container_of(blk_cb, struct raid5_plug_cb, cb);
4174
4175         if (cb->list.next == NULL)
4176                 INIT_LIST_HEAD(&cb->list);
4177
4178         if (!test_and_set_bit(STRIPE_ON_UNPLUG_LIST, &sh->state))
4179                 list_add_tail(&sh->lru, &cb->list);
4180         else
4181                 release_stripe(sh);
4182 }
4183
4184 static void make_discard_request(struct mddev *mddev, struct bio *bi)
4185 {
4186         struct r5conf *conf = mddev->private;
4187         sector_t logical_sector, last_sector;
4188         struct stripe_head *sh;
4189         int remaining;
4190         int stripe_sectors;
4191
4192         if (mddev->reshape_position != MaxSector)
4193                 /* Skip discard while reshape is happening */
4194                 return;
4195
4196         logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4197         last_sector = bi->bi_sector + (bi->bi_size>>9);
4198
4199         bi->bi_next = NULL;
4200         bi->bi_phys_segments = 1; /* over-loaded to count active stripes */
4201
4202         stripe_sectors = conf->chunk_sectors *
4203                 (conf->raid_disks - conf->max_degraded);
4204         logical_sector = DIV_ROUND_UP_SECTOR_T(logical_sector,
4205                                                stripe_sectors);
4206         sector_div(last_sector, stripe_sectors);
4207
4208         logical_sector *= conf->chunk_sectors;
4209         last_sector *= conf->chunk_sectors;
4210
4211         for (; logical_sector < last_sector;
4212              logical_sector += STRIPE_SECTORS) {
4213                 DEFINE_WAIT(w);
4214                 int d;
4215         again:
4216                 sh = get_active_stripe(conf, logical_sector, 0, 0, 0);
4217                 prepare_to_wait(&conf->wait_for_overlap, &w,
4218                                 TASK_UNINTERRUPTIBLE);
4219                 set_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
4220                 if (test_bit(STRIPE_SYNCING, &sh->state)) {
4221                         release_stripe(sh);
4222                         schedule();
4223                         goto again;
4224                 }
4225                 clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
4226                 spin_lock_irq(&sh->stripe_lock);
4227                 for (d = 0; d < conf->raid_disks; d++) {
4228                         if (d == sh->pd_idx || d == sh->qd_idx)
4229                                 continue;
4230                         if (sh->dev[d].towrite || sh->dev[d].toread) {
4231                                 set_bit(R5_Overlap, &sh->dev[d].flags);
4232                                 spin_unlock_irq(&sh->stripe_lock);
4233                                 release_stripe(sh);
4234                                 schedule();
4235                                 goto again;
4236                         }
4237                 }
4238                 set_bit(STRIPE_DISCARD, &sh->state);
4239                 finish_wait(&conf->wait_for_overlap, &w);
4240                 for (d = 0; d < conf->raid_disks; d++) {
4241                         if (d == sh->pd_idx || d == sh->qd_idx)
4242                                 continue;
4243                         sh->dev[d].towrite = bi;
4244                         set_bit(R5_OVERWRITE, &sh->dev[d].flags);
4245                         raid5_inc_bi_active_stripes(bi);
4246                 }
4247                 spin_unlock_irq(&sh->stripe_lock);
4248                 if (conf->mddev->bitmap) {
4249                         for (d = 0;
4250                              d < conf->raid_disks - conf->max_degraded;
4251                              d++)
4252                                 bitmap_startwrite(mddev->bitmap,
4253                                                   sh->sector,
4254                                                   STRIPE_SECTORS,
4255                                                   0);
4256                         sh->bm_seq = conf->seq_flush + 1;
4257                         set_bit(STRIPE_BIT_DELAY, &sh->state);
4258                 }
4259
4260                 set_bit(STRIPE_HANDLE, &sh->state);
4261                 clear_bit(STRIPE_DELAYED, &sh->state);
4262                 if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4263                         atomic_inc(&conf->preread_active_stripes);
4264                 release_stripe_plug(mddev, sh);
4265         }
4266
4267         remaining = raid5_dec_bi_active_stripes(bi);
4268         if (remaining == 0) {
4269                 md_write_end(mddev);
4270                 bio_endio(bi, 0);
4271         }
4272 }
4273
4274 static void make_request(struct mddev *mddev, struct bio * bi)
4275 {
4276         struct r5conf *conf = mddev->private;
4277         int dd_idx;
4278         sector_t new_sector;
4279         sector_t logical_sector, last_sector;
4280         struct stripe_head *sh;
4281         const int rw = bio_data_dir(bi);
4282         int remaining;
4283
4284         if (unlikely(bi->bi_rw & REQ_FLUSH)) {
4285                 md_flush_request(mddev, bi);
4286                 return;
4287         }
4288
4289         md_write_start(mddev, bi);
4290
4291         if (rw == READ &&
4292              mddev->reshape_position == MaxSector &&
4293              chunk_aligned_read(mddev,bi))
4294                 return;
4295
4296         if (unlikely(bi->bi_rw & REQ_DISCARD)) {
4297                 make_discard_request(mddev, bi);
4298                 return;
4299         }
4300
4301         logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4302         last_sector = bio_end_sector(bi);
4303         bi->bi_next = NULL;
4304         bi->bi_phys_segments = 1;       /* over-loaded to count active stripes */
4305
4306         for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
4307                 DEFINE_WAIT(w);
4308                 int previous;
4309
4310         retry:
4311                 previous = 0;
4312                 prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
4313                 if (unlikely(conf->reshape_progress != MaxSector)) {
4314                         /* spinlock is needed as reshape_progress may be
4315                          * 64bit on a 32bit platform, and so it might be
4316                          * possible to see a half-updated value
4317                          * Of course reshape_progress could change after
4318                          * the lock is dropped, so once we get a reference
4319                          * to the stripe that we think it is, we will have
4320                          * to check again.
4321                          */
4322                         spin_lock_irq(&conf->device_lock);
4323                         if (mddev->reshape_backwards
4324                             ? logical_sector < conf->reshape_progress
4325                             : logical_sector >= conf->reshape_progress) {
4326                                 previous = 1;
4327                         } else {
4328                                 if (mddev->reshape_backwards
4329                                     ? logical_sector < conf->reshape_safe
4330                                     : logical_sector >= conf->reshape_safe) {
4331                                         spin_unlock_irq(&conf->device_lock);
4332                                         schedule();
4333                                         goto retry;
4334                                 }
4335                         }
4336                         spin_unlock_irq(&conf->device_lock);
4337                 }
4338
4339                 new_sector = raid5_compute_sector(conf, logical_sector,
4340                                                   previous,
4341                                                   &dd_idx, NULL);
4342                 pr_debug("raid456: make_request, sector %llu logical %llu\n",
4343                         (unsigned long long)new_sector,
4344                         (unsigned long long)logical_sector);
4345
4346                 sh = get_active_stripe(conf, new_sector, previous,
4347                                        (bi->bi_rw&RWA_MASK), 0);
4348                 if (sh) {
4349                         if (unlikely(previous)) {
4350                                 /* expansion might have moved on while waiting for a
4351                                  * stripe, so we must do the range check again.
4352                                  * Expansion could still move past after this
4353                                  * test, but as we are holding a reference to
4354                                  * 'sh', we know that if that happens,
4355                                  *  STRIPE_EXPANDING will get set and the expansion
4356                                  * won't proceed until we finish with the stripe.
4357                                  */
4358                                 int must_retry = 0;
4359                                 spin_lock_irq(&conf->device_lock);
4360                                 if (mddev->reshape_backwards
4361                                     ? logical_sector >= conf->reshape_progress
4362                                     : logical_sector < conf->reshape_progress)
4363                                         /* mismatch, need to try again */
4364                                         must_retry = 1;
4365                                 spin_unlock_irq(&conf->device_lock);
4366                                 if (must_retry) {
4367                                         release_stripe(sh);
4368                                         schedule();
4369                                         goto retry;
4370                                 }
4371                         }
4372
4373                         if (rw == WRITE &&
4374                             logical_sector >= mddev->suspend_lo &&
4375                             logical_sector < mddev->suspend_hi) {
4376                                 release_stripe(sh);
4377                                 /* As the suspend_* range is controlled by
4378                                  * userspace, we want an interruptible
4379                                  * wait.
4380                                  */
4381                                 flush_signals(current);
4382                                 prepare_to_wait(&conf->wait_for_overlap,
4383                                                 &w, TASK_INTERRUPTIBLE);
4384                                 if (logical_sector >= mddev->suspend_lo &&
4385                                     logical_sector < mddev->suspend_hi)
4386                                         schedule();
4387                                 goto retry;
4388                         }
4389
4390                         if (test_bit(STRIPE_EXPANDING, &sh->state) ||
4391                             !add_stripe_bio(sh, bi, dd_idx, rw)) {
4392                                 /* Stripe is busy expanding or
4393                                  * add failed due to overlap.  Flush everything
4394                                  * and wait a while
4395                                  */
4396                                 md_wakeup_thread(mddev->thread);
4397                                 release_stripe(sh);
4398                                 schedule();
4399                                 goto retry;
4400                         }
4401                         finish_wait(&conf->wait_for_overlap, &w);
4402                         set_bit(STRIPE_HANDLE, &sh->state);
4403                         clear_bit(STRIPE_DELAYED, &sh->state);
4404                         if ((bi->bi_rw & REQ_SYNC) &&
4405                             !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4406                                 atomic_inc(&conf->preread_active_stripes);
4407                         release_stripe_plug(mddev, sh);
4408                 } else {
4409                         /* cannot get stripe for read-ahead, just give-up */
4410                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
4411                         finish_wait(&conf->wait_for_overlap, &w);
4412                         break;
4413                 }
4414         }
4415
4416         remaining = raid5_dec_bi_active_stripes(bi);
4417         if (remaining == 0) {
4418
4419                 if ( rw == WRITE )
4420                         md_write_end(mddev);
4421
4422                 trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
4423                                          bi, 0);
4424                 bio_endio(bi, 0);
4425         }
4426 }
4427
4428 static sector_t raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks);
4429
4430 static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *skipped)
4431 {
4432         /* reshaping is quite different to recovery/resync so it is
4433          * handled quite separately ... here.
4434          *
4435          * On each call to sync_request, we gather one chunk worth of
4436          * destination stripes and flag them as expanding.
4437          * Then we find all the source stripes and request reads.
4438          * As the reads complete, handle_stripe will copy the data
4439          * into the destination stripe and release that stripe.
4440          */
4441         struct r5conf *conf = mddev->private;
4442         struct stripe_head *sh;
4443         sector_t first_sector, last_sector;
4444         int raid_disks = conf->previous_raid_disks;
4445         int data_disks = raid_disks - conf->max_degraded;
4446         int new_data_disks = conf->raid_disks - conf->max_degraded;
4447         int i;
4448         int dd_idx;
4449         sector_t writepos, readpos, safepos;
4450         sector_t stripe_addr;
4451         int reshape_sectors;
4452         struct list_head stripes;
4453
4454         if (sector_nr == 0) {
4455                 /* If restarting in the middle, skip the initial sectors */
4456                 if (mddev->reshape_backwards &&
4457                     conf->reshape_progress < raid5_size(mddev, 0, 0)) {
4458                         sector_nr = raid5_size(mddev, 0, 0)
4459                                 - conf->reshape_progress;
4460                 } else if (!mddev->reshape_backwards &&
4461                            conf->reshape_progress > 0)
4462                         sector_nr = conf->reshape_progress;
4463                 sector_div(sector_nr, new_data_disks);
4464                 if (sector_nr) {
4465                         mddev->curr_resync_completed = sector_nr;
4466                         sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4467                         *skipped = 1;
4468                         return sector_nr;
4469                 }
4470         }
4471
4472         /* We need to process a full chunk at a time.
4473          * If old and new chunk sizes differ, we need to process the
4474          * largest of these
4475          */
4476         if (mddev->new_chunk_sectors > mddev->chunk_sectors)
4477                 reshape_sectors = mddev->new_chunk_sectors;
4478         else
4479                 reshape_sectors = mddev->chunk_sectors;
4480
4481         /* We update the metadata at least every 10 seconds, or when
4482          * the data about to be copied would over-write the source of
4483          * the data at the front of the range.  i.e. one new_stripe
4484          * along from reshape_progress new_maps to after where
4485          * reshape_safe old_maps to
4486          */
4487         writepos = conf->reshape_progress;
4488         sector_div(writepos, new_data_disks);
4489         readpos = conf->reshape_progress;
4490         sector_div(readpos, data_disks);
4491         safepos = conf->reshape_safe;
4492         sector_div(safepos, data_disks);
4493         if (mddev->reshape_backwards) {
4494                 writepos -= min_t(sector_t, reshape_sectors, writepos);
4495                 readpos += reshape_sectors;
4496                 safepos += reshape_sectors;
4497         } else {
4498                 writepos += reshape_sectors;
4499                 readpos -= min_t(sector_t, reshape_sectors, readpos);
4500                 safepos -= min_t(sector_t, reshape_sectors, safepos);
4501         }
4502
4503         /* Having calculated the 'writepos' possibly use it
4504          * to set 'stripe_addr' which is where we will write to.
4505          */
4506         if (mddev->reshape_backwards) {
4507                 BUG_ON(conf->reshape_progress == 0);
4508                 stripe_addr = writepos;
4509                 BUG_ON((mddev->dev_sectors &
4510                         ~((sector_t)reshape_sectors - 1))
4511                        - reshape_sectors - stripe_addr
4512                        != sector_nr);
4513         } else {
4514                 BUG_ON(writepos != sector_nr + reshape_sectors);
4515                 stripe_addr = sector_nr;
4516         }
4517
4518         /* 'writepos' is the most advanced device address we might write.
4519          * 'readpos' is the least advanced device address we might read.
4520          * 'safepos' is the least address recorded in the metadata as having
4521          *     been reshaped.
4522          * If there is a min_offset_diff, these are adjusted either by
4523          * increasing the safepos/readpos if diff is negative, or
4524          * increasing writepos if diff is positive.
4525          * If 'readpos' is then behind 'writepos', there is no way that we can
4526          * ensure safety in the face of a crash - that must be done by userspace
4527          * making a backup of the data.  So in that case there is no particular
4528          * rush to update metadata.
4529          * Otherwise if 'safepos' is behind 'writepos', then we really need to
4530          * update the metadata to advance 'safepos' to match 'readpos' so that
4531          * we can be safe in the event of a crash.
4532          * So we insist on updating metadata if safepos is behind writepos and
4533          * readpos is beyond writepos.
4534          * In any case, update the metadata every 10 seconds.
4535          * Maybe that number should be configurable, but I'm not sure it is
4536          * worth it.... maybe it could be a multiple of safemode_delay???
4537          */
4538         if (conf->min_offset_diff < 0) {
4539                 safepos += -conf->min_offset_diff;
4540                 readpos += -conf->min_offset_diff;
4541         } else
4542                 writepos += conf->min_offset_diff;
4543
4544         if ((mddev->reshape_backwards
4545              ? (safepos > writepos && readpos < writepos)
4546              : (safepos < writepos && readpos > writepos)) ||
4547             time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
4548                 /* Cannot proceed until we've updated the superblock... */
4549                 wait_event(conf->wait_for_overlap,
4550                            atomic_read(&conf->reshape_stripes)==0);
4551                 mddev->reshape_position = conf->reshape_progress;
4552                 mddev->curr_resync_completed = sector_nr;
4553                 conf->reshape_checkpoint = jiffies;
4554                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
4555                 md_wakeup_thread(mddev->thread);
4556                 wait_event(mddev->sb_wait, mddev->flags == 0 ||
4557                            kthread_should_stop());
4558                 spin_lock_irq(&conf->device_lock);
4559                 conf->reshape_safe = mddev->reshape_position;
4560                 spin_unlock_irq(&conf->device_lock);
4561                 wake_up(&conf->wait_for_overlap);
4562                 sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4563         }
4564
4565         INIT_LIST_HEAD(&stripes);
4566         for (i = 0; i < reshape_sectors; i += STRIPE_SECTORS) {
4567                 int j;
4568                 int skipped_disk = 0;
4569                 sh = get_active_stripe(conf, stripe_addr+i, 0, 0, 1);
4570                 set_bit(STRIPE_EXPANDING, &sh->state);
4571                 atomic_inc(&conf->reshape_stripes);
4572                 /* If any of this stripe is beyond the end of the old
4573                  * array, then we need to zero those blocks
4574                  */
4575                 for (j=sh->disks; j--;) {
4576                         sector_t s;
4577                         if (j == sh->pd_idx)
4578                                 continue;
4579                         if (conf->level == 6 &&
4580                             j == sh->qd_idx)
4581                                 continue;
4582                         s = compute_blocknr(sh, j, 0);
4583                         if (s < raid5_size(mddev, 0, 0)) {
4584                                 skipped_disk = 1;
4585                                 continue;
4586                         }
4587                         memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
4588                         set_bit(R5_Expanded, &sh->dev[j].flags);
4589                         set_bit(R5_UPTODATE, &sh->dev[j].flags);
4590                 }
4591                 if (!skipped_disk) {
4592                         set_bit(STRIPE_EXPAND_READY, &sh->state);
4593                         set_bit(STRIPE_HANDLE, &sh->state);
4594                 }
4595                 list_add(&sh->lru, &stripes);
4596         }
4597         spin_lock_irq(&conf->device_lock);
4598         if (mddev->reshape_backwards)
4599                 conf->reshape_progress -= reshape_sectors * new_data_disks;
4600         else
4601                 conf->reshape_progress += reshape_sectors * new_data_disks;
4602         spin_unlock_irq(&conf->device_lock);
4603         /* Ok, those stripe are ready. We can start scheduling
4604          * reads on the source stripes.
4605          * The source stripes are determined by mapping the first and last
4606          * block on the destination stripes.
4607          */
4608         first_sector =
4609                 raid5_compute_sector(conf, stripe_addr*(new_data_disks),
4610                                      1, &dd_idx, NULL);
4611         last_sector =
4612                 raid5_compute_sector(conf, ((stripe_addr+reshape_sectors)
4613                                             * new_data_disks - 1),
4614                                      1, &dd_idx, NULL);
4615         if (last_sector >= mddev->dev_sectors)
4616                 last_sector = mddev->dev_sectors - 1;
4617         while (first_sector <= last_sector) {
4618                 sh = get_active_stripe(conf, first_sector, 1, 0, 1);
4619                 set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
4620                 set_bit(STRIPE_HANDLE, &sh->state);
4621                 release_stripe(sh);
4622                 first_sector += STRIPE_SECTORS;
4623         }
4624         /* Now that the sources are clearly marked, we can release
4625          * the destination stripes
4626          */
4627         while (!list_empty(&stripes)) {
4628                 sh = list_entry(stripes.next, struct stripe_head, lru);
4629                 list_del_init(&sh->lru);
4630                 release_stripe(sh);
4631         }
4632         /* If this takes us to the resync_max point where we have to pause,
4633          * then we need to write out the superblock.
4634          */
4635         sector_nr += reshape_sectors;
4636         if ((sector_nr - mddev->curr_resync_completed) * 2
4637             >= mddev->resync_max - mddev->curr_resync_completed) {
4638                 /* Cannot proceed until we've updated the superblock... */
4639                 wait_event(conf->wait_for_overlap,
4640                            atomic_read(&conf->reshape_stripes) == 0);
4641                 mddev->reshape_position = conf->reshape_progress;
4642                 mddev->curr_resync_completed = sector_nr;
4643                 conf->reshape_checkpoint = jiffies;
4644                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
4645                 md_wakeup_thread(mddev->thread);
4646                 wait_event(mddev->sb_wait,
4647                            !test_bit(MD_CHANGE_DEVS, &mddev->flags)
4648                            || kthread_should_stop());
4649                 spin_lock_irq(&conf->device_lock);
4650                 conf->reshape_safe = mddev->reshape_position;
4651                 spin_unlock_irq(&conf->device_lock);
4652                 wake_up(&conf->wait_for_overlap);
4653                 sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4654         }
4655         return reshape_sectors;
4656 }
4657
4658 /* FIXME go_faster isn't used */
4659 static inline sector_t sync_request(struct mddev *mddev, sector_t sector_nr, int *skipped, int go_faster)
4660 {
4661         struct r5conf *conf = mddev->private;
4662         struct stripe_head *sh;
4663         sector_t max_sector = mddev->dev_sectors;
4664         sector_t sync_blocks;
4665         int still_degraded = 0;
4666         int i;
4667
4668         if (sector_nr >= max_sector) {
4669                 /* just being told to finish up .. nothing much to do */
4670
4671                 if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
4672                         end_reshape(conf);
4673                         return 0;
4674                 }
4675
4676                 if (mddev->curr_resync < max_sector) /* aborted */
4677                         bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
4678                                         &sync_blocks, 1);
4679                 else /* completed sync */
4680                         conf->fullsync = 0;
4681                 bitmap_close_sync(mddev->bitmap);
4682
4683                 return 0;
4684         }
4685
4686         /* Allow raid5_quiesce to complete */
4687         wait_event(conf->wait_for_overlap, conf->quiesce != 2);
4688
4689         if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
4690                 return reshape_request(mddev, sector_nr, skipped);
4691
4692         /* No need to check resync_max as we never do more than one
4693          * stripe, and as resync_max will always be on a chunk boundary,
4694          * if the check in md_do_sync didn't fire, there is no chance
4695          * of overstepping resync_max here
4696          */
4697
4698         /* if there is too many failed drives and we are trying
4699          * to resync, then assert that we are finished, because there is
4700          * nothing we can do.
4701          */
4702         if (mddev->degraded >= conf->max_degraded &&
4703             test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
4704                 sector_t rv = mddev->dev_sectors - sector_nr;
4705                 *skipped = 1;
4706                 return rv;
4707         }
4708         if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
4709             !conf->fullsync &&
4710             !bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
4711             sync_blocks >= STRIPE_SECTORS) {
4712                 /* we can skip this block, and probably more */
4713                 sync_blocks /= STRIPE_SECTORS;
4714                 *skipped = 1;
4715                 return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
4716         }
4717
4718         bitmap_cond_end_sync(mddev->bitmap, sector_nr);
4719
4720         sh = get_active_stripe(conf, sector_nr, 0, 1, 0);
4721         if (sh == NULL) {
4722                 sh = get_active_stripe(conf, sector_nr, 0, 0, 0);
4723                 /* make sure we don't swamp the stripe cache if someone else
4724                  * is trying to get access
4725                  */
4726                 schedule_timeout_uninterruptible(1);
4727         }
4728         /* Need to check if array will still be degraded after recovery/resync
4729          * We don't need to check the 'failed' flag as when that gets set,
4730          * recovery aborts.
4731          */
4732         for (i = 0; i < conf->raid_disks; i++)
4733                 if (conf->disks[i].rdev == NULL)
4734                         still_degraded = 1;
4735
4736         bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
4737
4738         set_bit(STRIPE_SYNC_REQUESTED, &sh->state);
4739
4740         handle_stripe(sh);
4741         release_stripe(sh);
4742
4743         return STRIPE_SECTORS;
4744 }
4745
4746 static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
4747 {
4748         /* We may not be able to submit a whole bio at once as there
4749          * may not be enough stripe_heads available.
4750          * We cannot pre-allocate enough stripe_heads as we may need
4751          * more than exist in the cache (if we allow ever large chunks).
4752          * So we do one stripe head at a time and record in
4753          * ->bi_hw_segments how many have been done.
4754          *
4755          * We *know* that this entire raid_bio is in one chunk, so
4756          * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
4757          */
4758         struct stripe_head *sh;
4759         int dd_idx;
4760         sector_t sector, logical_sector, last_sector;
4761         int scnt = 0;
4762         int remaining;
4763         int handled = 0;
4764
4765         logical_sector = raid_bio->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4766         sector = raid5_compute_sector(conf, logical_sector,
4767                                       0, &dd_idx, NULL);
4768         last_sector = bio_end_sector(raid_bio);
4769
4770         for (; logical_sector < last_sector;
4771              logical_sector += STRIPE_SECTORS,
4772                      sector += STRIPE_SECTORS,
4773                      scnt++) {
4774
4775                 if (scnt < raid5_bi_processed_stripes(raid_bio))
4776                         /* already done this stripe */
4777                         continue;
4778
4779                 sh = get_active_stripe(conf, sector, 0, 1, 0);
4780
4781                 if (!sh) {
4782                         /* failed to get a stripe - must wait */
4783                         raid5_set_bi_processed_stripes(raid_bio, scnt);
4784                         conf->retry_read_aligned = raid_bio;
4785                         return handled;
4786                 }
4787
4788                 if (!add_stripe_bio(sh, raid_bio, dd_idx, 0)) {
4789                         release_stripe(sh);
4790                         raid5_set_bi_processed_stripes(raid_bio, scnt);
4791                         conf->retry_read_aligned = raid_bio;
4792                         return handled;
4793                 }
4794
4795                 set_bit(R5_ReadNoMerge, &sh->dev[dd_idx].flags);
4796                 handle_stripe(sh);
4797                 release_stripe(sh);
4798                 handled++;
4799         }
4800         remaining = raid5_dec_bi_active_stripes(raid_bio);
4801         if (remaining == 0) {
4802                 trace_block_bio_complete(bdev_get_queue(raid_bio->bi_bdev),
4803                                          raid_bio, 0);
4804                 bio_endio(raid_bio, 0);
4805         }
4806         if (atomic_dec_and_test(&conf->active_aligned_reads))
4807                 wake_up(&conf->wait_for_stripe);
4808         return handled;
4809 }
4810
4811 #define MAX_STRIPE_BATCH 8
4812 static int handle_active_stripes(struct r5conf *conf)
4813 {
4814         struct stripe_head *batch[MAX_STRIPE_BATCH], *sh;
4815         int i, batch_size = 0;
4816
4817         while (batch_size < MAX_STRIPE_BATCH &&
4818                         (sh = __get_priority_stripe(conf)) != NULL)
4819                 batch[batch_size++] = sh;
4820
4821         if (batch_size == 0)
4822                 return batch_size;
4823         spin_unlock_irq(&conf->device_lock);
4824
4825         for (i = 0; i < batch_size; i++)
4826                 handle_stripe(batch[i]);
4827
4828         cond_resched();
4829
4830         spin_lock_irq(&conf->device_lock);
4831         for (i = 0; i < batch_size; i++)
4832                 __release_stripe(conf, batch[i]);
4833         return batch_size;
4834 }
4835
4836 /*
4837  * This is our raid5 kernel thread.
4838  *
4839  * We scan the hash table for stripes which can be handled now.
4840  * During the scan, completed stripes are saved for us by the interrupt
4841  * handler, so that they will not have to wait for our next wakeup.
4842  */
4843 static void raid5d(struct md_thread *thread)
4844 {
4845         struct mddev *mddev = thread->mddev;
4846         struct r5conf *conf = mddev->private;
4847         int handled;
4848         struct blk_plug plug;
4849
4850         pr_debug("+++ raid5d active\n");
4851
4852         md_check_recovery(mddev);
4853
4854         blk_start_plug(&plug);
4855         handled = 0;
4856         spin_lock_irq(&conf->device_lock);
4857         while (1) {
4858                 struct bio *bio;
4859                 int batch_size;
4860
4861                 if (
4862                     !list_empty(&conf->bitmap_list)) {
4863                         /* Now is a good time to flush some bitmap updates */
4864                         conf->seq_flush++;
4865                         spin_unlock_irq(&conf->device_lock);
4866                         bitmap_unplug(mddev->bitmap);
4867                         spin_lock_irq(&conf->device_lock);
4868                         conf->seq_write = conf->seq_flush;
4869                         activate_bit_delay(conf);
4870                 }
4871                 raid5_activate_delayed(conf);
4872
4873                 while ((bio = remove_bio_from_retry(conf))) {
4874                         int ok;
4875                         spin_unlock_irq(&conf->device_lock);
4876                         ok = retry_aligned_read(conf, bio);
4877                         spin_lock_irq(&conf->device_lock);
4878                         if (!ok)
4879                                 break;
4880                         handled++;
4881                 }
4882
4883                 batch_size = handle_active_stripes(conf);
4884                 if (!batch_size)
4885                         break;
4886                 handled += batch_size;
4887
4888                 if (mddev->flags & ~(1<<MD_CHANGE_PENDING)) {
4889                         spin_unlock_irq(&conf->device_lock);
4890                         md_check_recovery(mddev);
4891                         spin_lock_irq(&conf->device_lock);
4892                 }
4893         }
4894         pr_debug("%d stripes handled\n", handled);
4895
4896         spin_unlock_irq(&conf->device_lock);
4897
4898         async_tx_issue_pending_all();
4899         blk_finish_plug(&plug);
4900
4901         pr_debug("--- raid5d inactive\n");
4902 }
4903
4904 static ssize_t
4905 raid5_show_stripe_cache_size(struct mddev *mddev, char *page)
4906 {
4907         struct r5conf *conf = mddev->private;
4908         if (conf)
4909                 return sprintf(page, "%d\n", conf->max_nr_stripes);
4910         else
4911                 return 0;
4912 }
4913
4914 int
4915 raid5_set_cache_size(struct mddev *mddev, int size)
4916 {
4917         struct r5conf *conf = mddev->private;
4918         int err;
4919
4920         if (size <= 16 || size > 32768)
4921                 return -EINVAL;
4922         while (size < conf->max_nr_stripes) {
4923                 if (drop_one_stripe(conf))
4924                         conf->max_nr_stripes--;
4925                 else
4926                         break;
4927         }
4928         err = md_allow_write(mddev);
4929         if (err)
4930                 return err;
4931         while (size > conf->max_nr_stripes) {
4932                 if (grow_one_stripe(conf))
4933                         conf->max_nr_stripes++;
4934                 else break;
4935         }
4936         return 0;
4937 }
4938 EXPORT_SYMBOL(raid5_set_cache_size);
4939
4940 static ssize_t
4941 raid5_store_stripe_cache_size(struct mddev *mddev, const char *page, size_t len)
4942 {
4943         struct r5conf *conf = mddev->private;
4944         unsigned long new;
4945         int err;
4946
4947         if (len >= PAGE_SIZE)
4948                 return -EINVAL;
4949         if (!conf)
4950                 return -ENODEV;
4951
4952         if (strict_strtoul(page, 10, &new))
4953                 return -EINVAL;
4954         err = raid5_set_cache_size(mddev, new);
4955         if (err)
4956                 return err;
4957         return len;
4958 }
4959
4960 static struct md_sysfs_entry
4961 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
4962                                 raid5_show_stripe_cache_size,
4963                                 raid5_store_stripe_cache_size);
4964
4965 static ssize_t
4966 raid5_show_preread_threshold(struct mddev *mddev, char *page)
4967 {
4968         struct r5conf *conf = mddev->private;
4969         if (conf)
4970                 return sprintf(page, "%d\n", conf->bypass_threshold);
4971         else
4972                 return 0;
4973 }
4974
4975 static ssize_t
4976 raid5_store_preread_threshold(struct mddev *mddev, const char *page, size_t len)
4977 {
4978         struct r5conf *conf = mddev->private;
4979         unsigned long new;
4980         if (len >= PAGE_SIZE)
4981                 return -EINVAL;
4982         if (!conf)
4983                 return -ENODEV;
4984
4985         if (strict_strtoul(page, 10, &new))
4986                 return -EINVAL;
4987         if (new > conf->max_nr_stripes)
4988                 return -EINVAL;
4989         conf->bypass_threshold = new;
4990         return len;
4991 }
4992
4993 static struct md_sysfs_entry
4994 raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold,
4995                                         S_IRUGO | S_IWUSR,
4996                                         raid5_show_preread_threshold,
4997                                         raid5_store_preread_threshold);
4998
4999 static ssize_t
5000 stripe_cache_active_show(struct mddev *mddev, char *page)
5001 {
5002         struct r5conf *conf = mddev->private;
5003         if (conf)
5004                 return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
5005         else
5006                 return 0;
5007 }
5008
5009 static struct md_sysfs_entry
5010 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
5011
5012 static struct attribute *raid5_attrs[] =  {
5013         &raid5_stripecache_size.attr,
5014         &raid5_stripecache_active.attr,
5015         &raid5_preread_bypass_threshold.attr,
5016         NULL,
5017 };
5018 static struct attribute_group raid5_attrs_group = {
5019         .name = NULL,
5020         .attrs = raid5_attrs,
5021 };
5022
5023 static sector_t
5024 raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks)
5025 {
5026         struct r5conf *conf = mddev->private;
5027
5028         if (!sectors)
5029                 sectors = mddev->dev_sectors;
5030         if (!raid_disks)
5031                 /* size is defined by the smallest of previous and new size */
5032                 raid_disks = min(conf->raid_disks, conf->previous_raid_disks);
5033
5034         sectors &= ~((sector_t)mddev->chunk_sectors - 1);
5035         sectors &= ~((sector_t)mddev->new_chunk_sectors - 1);
5036         return sectors * (raid_disks - conf->max_degraded);
5037 }
5038
5039 static void raid5_free_percpu(struct r5conf *conf)
5040 {
5041         struct raid5_percpu *percpu;
5042         unsigned long cpu;
5043
5044         if (!conf->percpu)
5045                 return;
5046
5047         get_online_cpus();
5048         for_each_possible_cpu(cpu) {
5049                 percpu = per_cpu_ptr(conf->percpu, cpu);
5050                 safe_put_page(percpu->spare_page);
5051                 kfree(percpu->scribble);
5052         }
5053 #ifdef CONFIG_HOTPLUG_CPU
5054         unregister_cpu_notifier(&conf->cpu_notify);
5055 #endif
5056         put_online_cpus();
5057
5058         free_percpu(conf->percpu);
5059 }
5060
5061 static void free_conf(struct r5conf *conf)
5062 {
5063         shrink_stripes(conf);
5064         raid5_free_percpu(conf);
5065         kfree(conf->disks);
5066         kfree(conf->stripe_hashtbl);
5067         kfree(conf);
5068 }
5069
5070 #ifdef CONFIG_HOTPLUG_CPU
5071 static int raid456_cpu_notify(struct notifier_block *nfb, unsigned long action,
5072                               void *hcpu)
5073 {
5074         struct r5conf *conf = container_of(nfb, struct r5conf, cpu_notify);
5075         long cpu = (long)hcpu;
5076         struct raid5_percpu *percpu = per_cpu_ptr(conf->percpu, cpu);
5077
5078         switch (action) {
5079         case CPU_UP_PREPARE:
5080         case CPU_UP_PREPARE_FROZEN:
5081                 if (conf->level == 6 && !percpu->spare_page)
5082                         percpu->spare_page = alloc_page(GFP_KERNEL);
5083                 if (!percpu->scribble)
5084                         percpu->scribble = kmalloc(conf->scribble_len, GFP_KERNEL);
5085
5086                 if (!percpu->scribble ||
5087                     (conf->level == 6 && !percpu->spare_page)) {
5088                         safe_put_page(percpu->spare_page);
5089                         kfree(percpu->scribble);
5090                         pr_err("%s: failed memory allocation for cpu%ld\n",
5091                                __func__, cpu);
5092                         return notifier_from_errno(-ENOMEM);
5093                 }
5094                 break;
5095         case CPU_DEAD:
5096         case CPU_DEAD_FROZEN:
5097                 safe_put_page(percpu->spare_page);
5098                 kfree(percpu->scribble);
5099                 percpu->spare_page = NULL;
5100                 percpu->scribble = NULL;
5101                 break;
5102         default:
5103                 break;
5104         }
5105         return NOTIFY_OK;
5106 }
5107 #endif
5108
5109 static int raid5_alloc_percpu(struct r5conf *conf)
5110 {
5111         unsigned long cpu;
5112         struct page *spare_page;
5113         struct raid5_percpu __percpu *allcpus;
5114         void *scribble;
5115         int err;
5116
5117         allcpus = alloc_percpu(struct raid5_percpu);
5118         if (!allcpus)
5119                 return -ENOMEM;
5120         conf->percpu = allcpus;
5121
5122         get_online_cpus();
5123         err = 0;
5124         for_each_present_cpu(cpu) {
5125                 if (conf->level == 6) {
5126                         spare_page = alloc_page(GFP_KERNEL);
5127                         if (!spare_page) {
5128                                 err = -ENOMEM;
5129                                 break;
5130                         }
5131                         per_cpu_ptr(conf->percpu, cpu)->spare_page = spare_page;
5132                 }
5133                 scribble = kmalloc(conf->scribble_len, GFP_KERNEL);
5134                 if (!scribble) {
5135                         err = -ENOMEM;
5136                         break;
5137                 }
5138                 per_cpu_ptr(conf->percpu, cpu)->scribble = scribble;
5139         }
5140 #ifdef CONFIG_HOTPLUG_CPU
5141         conf->cpu_notify.notifier_call = raid456_cpu_notify;
5142         conf->cpu_notify.priority = 0;
5143         if (err == 0)
5144                 err = register_cpu_notifier(&conf->cpu_notify);
5145 #endif
5146         put_online_cpus();
5147
5148         return err;
5149 }
5150
5151 static struct r5conf *setup_conf(struct mddev *mddev)
5152 {
5153         struct r5conf *conf;
5154         int raid_disk, memory, max_disks;
5155         struct md_rdev *rdev;
5156         struct disk_info *disk;
5157         char pers_name[6];
5158
5159         if (mddev->new_level != 5
5160             && mddev->new_level != 4
5161             && mddev->new_level != 6) {
5162                 printk(KERN_ERR "md/raid:%s: raid level not set to 4/5/6 (%d)\n",
5163                        mdname(mddev), mddev->new_level);
5164                 return ERR_PTR(-EIO);
5165         }
5166         if ((mddev->new_level == 5
5167              && !algorithm_valid_raid5(mddev->new_layout)) ||
5168             (mddev->new_level == 6
5169              && !algorithm_valid_raid6(mddev->new_layout))) {
5170                 printk(KERN_ERR "md/raid:%s: layout %d not supported\n",
5171                        mdname(mddev), mddev->new_layout);
5172                 return ERR_PTR(-EIO);
5173         }
5174         if (mddev->new_level == 6 && mddev->raid_disks < 4) {
5175                 printk(KERN_ERR "md/raid:%s: not enough configured devices (%d, minimum 4)\n",
5176                        mdname(mddev), mddev->raid_disks);
5177                 return ERR_PTR(-EINVAL);
5178         }
5179
5180         if (!mddev->new_chunk_sectors ||
5181             (mddev->new_chunk_sectors << 9) % PAGE_SIZE ||
5182             !is_power_of_2(mddev->new_chunk_sectors)) {
5183                 printk(KERN_ERR "md/raid:%s: invalid chunk size %d\n",
5184                        mdname(mddev), mddev->new_chunk_sectors << 9);
5185                 return ERR_PTR(-EINVAL);
5186         }
5187
5188         conf = kzalloc(sizeof(struct r5conf), GFP_KERNEL);
5189         if (conf == NULL)
5190                 goto abort;
5191         spin_lock_init(&conf->device_lock);
5192         init_waitqueue_head(&conf->wait_for_stripe);
5193         init_waitqueue_head(&conf->wait_for_overlap);
5194         INIT_LIST_HEAD(&conf->handle_list);
5195         INIT_LIST_HEAD(&conf->hold_list);
5196         INIT_LIST_HEAD(&conf->delayed_list);
5197         INIT_LIST_HEAD(&conf->bitmap_list);
5198         INIT_LIST_HEAD(&conf->inactive_list);
5199         atomic_set(&conf->active_stripes, 0);
5200         atomic_set(&conf->preread_active_stripes, 0);
5201         atomic_set(&conf->active_aligned_reads, 0);
5202         conf->bypass_threshold = BYPASS_THRESHOLD;
5203         conf->recovery_disabled = mddev->recovery_disabled - 1;
5204
5205         conf->raid_disks = mddev->raid_disks;
5206         if (mddev->reshape_position == MaxSector)
5207                 conf->previous_raid_disks = mddev->raid_disks;
5208         else
5209                 conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
5210         max_disks = max(conf->raid_disks, conf->previous_raid_disks);
5211         conf->scribble_len = scribble_len(max_disks);
5212
5213         conf->disks = kzalloc(max_disks * sizeof(struct disk_info),
5214                               GFP_KERNEL);
5215         if (!conf->disks)
5216                 goto abort;
5217
5218         conf->mddev = mddev;
5219
5220         if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
5221                 goto abort;
5222
5223         conf->level = mddev->new_level;
5224         if (raid5_alloc_percpu(conf) != 0)
5225                 goto abort;
5226
5227         pr_debug("raid456: run(%s) called.\n", mdname(mddev));
5228
5229         rdev_for_each(rdev, mddev) {
5230                 raid_disk = rdev->raid_disk;
5231                 if (raid_disk >= max_disks
5232                     || raid_disk < 0)
5233                         continue;
5234                 disk = conf->disks + raid_disk;
5235
5236                 if (test_bit(Replacement, &rdev->flags)) {
5237                         if (disk->replacement)
5238                                 goto abort;
5239                         disk->replacement = rdev;
5240                 } else {
5241                         if (disk->rdev)
5242                                 goto abort;
5243                         disk->rdev = rdev;
5244                 }
5245
5246                 if (test_bit(In_sync, &rdev->flags)) {
5247                         char b[BDEVNAME_SIZE];
5248                         printk(KERN_INFO "md/raid:%s: device %s operational as raid"
5249                                " disk %d\n",
5250                                mdname(mddev), bdevname(rdev->bdev, b), raid_disk);
5251                 } else if (rdev->saved_raid_disk != raid_disk)
5252                         /* Cannot rely on bitmap to complete recovery */
5253                         conf->fullsync = 1;
5254         }
5255
5256         conf->chunk_sectors = mddev->new_chunk_sectors;
5257         conf->level = mddev->new_level;
5258         if (conf->level == 6)
5259                 conf->max_degraded = 2;
5260         else
5261                 conf->max_degraded = 1;
5262         conf->algorithm = mddev->new_layout;
5263         conf->max_nr_stripes = NR_STRIPES;
5264         conf->reshape_progress = mddev->reshape_position;
5265         if (conf->reshape_progress != MaxSector) {
5266                 conf->prev_chunk_sectors = mddev->chunk_sectors;
5267                 conf->prev_algo = mddev->layout;
5268         }
5269
5270         memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
5271                  max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
5272         if (grow_stripes(conf, conf->max_nr_stripes)) {
5273                 printk(KERN_ERR
5274                        "md/raid:%s: couldn't allocate %dkB for buffers\n",
5275                        mdname(mddev), memory);
5276                 goto abort;
5277         } else
5278                 printk(KERN_INFO "md/raid:%s: allocated %dkB\n",
5279                        mdname(mddev), memory);
5280
5281         sprintf(pers_name, "raid%d", mddev->new_level);
5282         conf->thread = md_register_thread(raid5d, mddev, pers_name);
5283         if (!conf->thread) {
5284                 printk(KERN_ERR
5285                        "md/raid:%s: couldn't allocate thread.\n",
5286                        mdname(mddev));
5287                 goto abort;
5288         }
5289
5290         return conf;
5291
5292  abort:
5293         if (conf) {
5294                 free_conf(conf);
5295                 return ERR_PTR(-EIO);
5296         } else
5297                 return ERR_PTR(-ENOMEM);
5298 }
5299
5300
5301 static int only_parity(int raid_disk, int algo, int raid_disks, int max_degraded)
5302 {
5303         switch (algo) {
5304         case ALGORITHM_PARITY_0:
5305                 if (raid_disk < max_degraded)
5306                         return 1;
5307                 break;
5308         case ALGORITHM_PARITY_N:
5309                 if (raid_disk >= raid_disks - max_degraded)
5310                         return 1;
5311                 break;
5312         case ALGORITHM_PARITY_0_6:
5313                 if (raid_disk == 0 ||
5314                     raid_disk == raid_disks - 1)
5315                         return 1;
5316                 break;
5317         case ALGORITHM_LEFT_ASYMMETRIC_6:
5318         case ALGORITHM_RIGHT_ASYMMETRIC_6:
5319         case ALGORITHM_LEFT_SYMMETRIC_6:
5320         case ALGORITHM_RIGHT_SYMMETRIC_6:
5321                 if (raid_disk == raid_disks - 1)
5322                         return 1;
5323         }
5324         return 0;
5325 }
5326
5327 static int run(struct mddev *mddev)
5328 {
5329         struct r5conf *conf;
5330         int working_disks = 0;
5331         int dirty_parity_disks = 0;
5332         struct md_rdev *rdev;
5333         sector_t reshape_offset = 0;
5334         int i;
5335         long long min_offset_diff = 0;
5336         int first = 1;
5337
5338         if (mddev->recovery_cp != MaxSector)
5339                 printk(KERN_NOTICE "md/raid:%s: not clean"
5340                        " -- starting background reconstruction\n",
5341                        mdname(mddev));
5342
5343         rdev_for_each(rdev, mddev) {
5344                 long long diff;
5345                 if (rdev->raid_disk < 0)
5346                         continue;
5347                 diff = (rdev->new_data_offset - rdev->data_offset);
5348                 if (first) {
5349                         min_offset_diff = diff;
5350                         first = 0;
5351                 } else if (mddev->reshape_backwards &&
5352                          diff < min_offset_diff)
5353                         min_offset_diff = diff;
5354                 else if (!mddev->reshape_backwards &&
5355                          diff > min_offset_diff)
5356                         min_offset_diff = diff;
5357         }
5358
5359         if (mddev->reshape_position != MaxSector) {
5360                 /* Check that we can continue the reshape.
5361                  * Difficulties arise if the stripe we would write to
5362                  * next is at or after the stripe we would read from next.
5363                  * For a reshape that changes the number of devices, this
5364                  * is only possible for a very short time, and mdadm makes
5365                  * sure that time appears to have past before assembling
5366                  * the array.  So we fail if that time hasn't passed.
5367                  * For a reshape that keeps the number of devices the same
5368                  * mdadm must be monitoring the reshape can keeping the
5369                  * critical areas read-only and backed up.  It will start
5370                  * the array in read-only mode, so we check for that.
5371                  */
5372                 sector_t here_new, here_old;
5373                 int old_disks;
5374                 int max_degraded = (mddev->level == 6 ? 2 : 1);
5375
5376                 if (mddev->new_level != mddev->level) {
5377                         printk(KERN_ERR "md/raid:%s: unsupported reshape "
5378                                "required - aborting.\n",
5379                                mdname(mddev));
5380                         return -EINVAL;
5381                 }
5382                 old_disks = mddev->raid_disks - mddev->delta_disks;
5383                 /* reshape_position must be on a new-stripe boundary, and one
5384                  * further up in new geometry must map after here in old
5385                  * geometry.
5386                  */
5387                 here_new = mddev->reshape_position;
5388                 if (sector_div(here_new, mddev->new_chunk_sectors *
5389                                (mddev->raid_disks - max_degraded))) {
5390                         printk(KERN_ERR "md/raid:%s: reshape_position not "
5391                                "on a stripe boundary\n", mdname(mddev));
5392                         return -EINVAL;
5393                 }
5394                 reshape_offset = here_new * mddev->new_chunk_sectors;
5395                 /* here_new is the stripe we will write to */
5396                 here_old = mddev->reshape_position;
5397                 sector_div(here_old, mddev->chunk_sectors *
5398                            (old_disks-max_degraded));
5399                 /* here_old is the first stripe that we might need to read
5400                  * from */
5401                 if (mddev->delta_disks == 0) {
5402                         if ((here_new * mddev->new_chunk_sectors !=
5403                              here_old * mddev->chunk_sectors)) {
5404                                 printk(KERN_ERR "md/raid:%s: reshape position is"
5405                                        " confused - aborting\n", mdname(mddev));
5406                                 return -EINVAL;
5407                         }
5408                         /* We cannot be sure it is safe to start an in-place
5409                          * reshape.  It is only safe if user-space is monitoring
5410                          * and taking constant backups.
5411                          * mdadm always starts a situation like this in
5412                          * readonly mode so it can take control before
5413                          * allowing any writes.  So just check for that.
5414                          */
5415                         if (abs(min_offset_diff) >= mddev->chunk_sectors &&
5416                             abs(min_offset_diff) >= mddev->new_chunk_sectors)
5417                                 /* not really in-place - so OK */;
5418                         else if (mddev->ro == 0) {
5419                                 printk(KERN_ERR "md/raid:%s: in-place reshape "
5420                                        "must be started in read-only mode "
5421                                        "- aborting\n",
5422                                        mdname(mddev));
5423                                 return -EINVAL;
5424                         }
5425                 } else if (mddev->reshape_backwards
5426                     ? (here_new * mddev->new_chunk_sectors + min_offset_diff <=
5427                        here_old * mddev->chunk_sectors)
5428                     : (here_new * mddev->new_chunk_sectors >=
5429                        here_old * mddev->chunk_sectors + (-min_offset_diff))) {
5430                         /* Reading from the same stripe as writing to - bad */
5431                         printk(KERN_ERR "md/raid:%s: reshape_position too early for "
5432                                "auto-recovery - aborting.\n",
5433                                mdname(mddev));
5434                         return -EINVAL;
5435                 }
5436                 printk(KERN_INFO "md/raid:%s: reshape will continue\n",
5437                        mdname(mddev));
5438                 /* OK, we should be able to continue; */
5439         } else {
5440                 BUG_ON(mddev->level != mddev->new_level);
5441                 BUG_ON(mddev->layout != mddev->new_layout);
5442                 BUG_ON(mddev->chunk_sectors != mddev->new_chunk_sectors);
5443                 BUG_ON(mddev->delta_disks != 0);
5444         }
5445
5446         if (mddev->private == NULL)
5447                 conf = setup_conf(mddev);
5448         else
5449                 conf = mddev->private;
5450
5451         if (IS_ERR(conf))
5452                 return PTR_ERR(conf);
5453
5454         conf->min_offset_diff = min_offset_diff;
5455         mddev->thread = conf->thread;
5456         conf->thread = NULL;
5457         mddev->private = conf;
5458
5459         for (i = 0; i < conf->raid_disks && conf->previous_raid_disks;
5460              i++) {
5461                 rdev = conf->disks[i].rdev;
5462                 if (!rdev && conf->disks[i].replacement) {
5463                         /* The replacement is all we have yet */
5464                         rdev = conf->disks[i].replacement;
5465                         conf->disks[i].replacement = NULL;
5466                         clear_bit(Replacement, &rdev->flags);
5467                         conf->disks[i].rdev = rdev;
5468                 }
5469                 if (!rdev)
5470                         continue;
5471                 if (conf->disks[i].replacement &&
5472                     conf->reshape_progress != MaxSector) {
5473                         /* replacements and reshape simply do not mix. */
5474                         printk(KERN_ERR "md: cannot handle concurrent "
5475                                "replacement and reshape.\n");
5476                         goto abort;
5477                 }
5478                 if (test_bit(In_sync, &rdev->flags)) {
5479                         working_disks++;
5480                         continue;
5481                 }
5482                 /* This disc is not fully in-sync.  However if it
5483                  * just stored parity (beyond the recovery_offset),
5484                  * when we don't need to be concerned about the
5485                  * array being dirty.
5486                  * When reshape goes 'backwards', we never have
5487                  * partially completed devices, so we only need
5488                  * to worry about reshape going forwards.
5489                  */
5490                 /* Hack because v0.91 doesn't store recovery_offset properly. */
5491                 if (mddev->major_version == 0 &&
5492                     mddev->minor_version > 90)
5493                         rdev->recovery_offset = reshape_offset;
5494
5495                 if (rdev->recovery_offset < reshape_offset) {
5496                         /* We need to check old and new layout */
5497                         if (!only_parity(rdev->raid_disk,
5498                                          conf->algorithm,
5499                                          conf->raid_disks,
5500                                          conf->max_degraded))
5501                                 continue;
5502                 }
5503                 if (!only_parity(rdev->raid_disk,
5504                                  conf->prev_algo,
5505                                  conf->previous_raid_disks,
5506                                  conf->max_degraded))
5507                         continue;
5508                 dirty_parity_disks++;
5509         }
5510
5511         /*
5512          * 0 for a fully functional array, 1 or 2 for a degraded array.
5513          */
5514         mddev->degraded = calc_degraded(conf);
5515
5516         if (has_failed(conf)) {
5517                 printk(KERN_ERR "md/raid:%s: not enough operational devices"
5518                         " (%d/%d failed)\n",
5519                         mdname(mddev), mddev->degraded, conf->raid_disks);
5520                 goto abort;
5521         }
5522
5523         /* device size must be a multiple of chunk size */
5524         mddev->dev_sectors &= ~(mddev->chunk_sectors - 1);
5525         mddev->resync_max_sectors = mddev->dev_sectors;
5526
5527         if (mddev->degraded > dirty_parity_disks &&
5528             mddev->recovery_cp != MaxSector) {
5529                 if (mddev->ok_start_degraded)
5530                         printk(KERN_WARNING
5531                                "md/raid:%s: starting dirty degraded array"
5532                                " - data corruption possible.\n",
5533                                mdname(mddev));
5534                 else {
5535                         printk(KERN_ERR
5536                                "md/raid:%s: cannot start dirty degraded array.\n",
5537                                mdname(mddev));
5538                         goto abort;
5539                 }
5540         }
5541
5542         if (mddev->degraded == 0)
5543                 printk(KERN_INFO "md/raid:%s: raid level %d active with %d out of %d"
5544                        " devices, algorithm %d\n", mdname(mddev), conf->level,
5545                        mddev->raid_disks-mddev->degraded, mddev->raid_disks,
5546                        mddev->new_layout);
5547         else
5548                 printk(KERN_ALERT "md/raid:%s: raid level %d active with %d"
5549                        " out of %d devices, algorithm %d\n",
5550                        mdname(mddev), conf->level,
5551                        mddev->raid_disks - mddev->degraded,
5552                        mddev->raid_disks, mddev->new_layout);
5553
5554         print_raid5_conf(conf);
5555
5556         if (conf->reshape_progress != MaxSector) {
5557                 conf->reshape_safe = conf->reshape_progress;
5558                 atomic_set(&conf->reshape_stripes, 0);
5559                 clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
5560                 clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
5561                 set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
5562                 set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
5563                 mddev->sync_thread = md_register_thread(md_do_sync, mddev,
5564                                                         "reshape");
5565         }
5566
5567
5568         /* Ok, everything is just fine now */
5569         if (mddev->to_remove == &raid5_attrs_group)
5570                 mddev->to_remove = NULL;
5571         else if (mddev->kobj.sd &&
5572             sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
5573                 printk(KERN_WARNING
5574                        "raid5: failed to create sysfs attributes for %s\n",
5575                        mdname(mddev));
5576         md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
5577
5578         if (mddev->queue) {
5579                 int chunk_size;
5580                 bool discard_supported = true;
5581                 /* read-ahead size must cover two whole stripes, which
5582                  * is 2 * (datadisks) * chunksize where 'n' is the
5583                  * number of raid devices
5584                  */
5585                 int data_disks = conf->previous_raid_disks - conf->max_degraded;
5586                 int stripe = data_disks *
5587                         ((mddev->chunk_sectors << 9) / PAGE_SIZE);
5588                 if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
5589                         mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
5590
5591                 blk_queue_merge_bvec(mddev->queue, raid5_mergeable_bvec);
5592
5593                 mddev->queue->backing_dev_info.congested_data = mddev;
5594                 mddev->queue->backing_dev_info.congested_fn = raid5_congested;
5595
5596                 chunk_size = mddev->chunk_sectors << 9;
5597                 blk_queue_io_min(mddev->queue, chunk_size);
5598                 blk_queue_io_opt(mddev->queue, chunk_size *
5599                                  (conf->raid_disks - conf->max_degraded));
5600                 /*
5601                  * We can only discard a whole stripe. It doesn't make sense to
5602                  * discard data disk but write parity disk
5603                  */
5604                 stripe = stripe * PAGE_SIZE;
5605                 /* Round up to power of 2, as discard handling
5606                  * currently assumes that */
5607                 while ((stripe-1) & stripe)
5608                         stripe = (stripe | (stripe-1)) + 1;
5609                 mddev->queue->limits.discard_alignment = stripe;
5610                 mddev->queue->limits.discard_granularity = stripe;
5611                 /*
5612                  * unaligned part of discard request will be ignored, so can't
5613                  * guarantee discard_zerors_data
5614                  */
5615                 mddev->queue->limits.discard_zeroes_data = 0;
5616
5617                 blk_queue_max_write_same_sectors(mddev->queue, 0);
5618
5619                 rdev_for_each(rdev, mddev) {
5620                         disk_stack_limits(mddev->gendisk, rdev->bdev,
5621                                           rdev->data_offset << 9);
5622                         disk_stack_limits(mddev->gendisk, rdev->bdev,
5623                                           rdev->new_data_offset << 9);
5624                         /*
5625                          * discard_zeroes_data is required, otherwise data
5626                          * could be lost. Consider a scenario: discard a stripe
5627                          * (the stripe could be inconsistent if
5628                          * discard_zeroes_data is 0); write one disk of the
5629                          * stripe (the stripe could be inconsistent again
5630                          * depending on which disks are used to calculate
5631                          * parity); the disk is broken; The stripe data of this
5632                          * disk is lost.
5633                          */
5634                         if (!blk_queue_discard(bdev_get_queue(rdev->bdev)) ||
5635                             !bdev_get_queue(rdev->bdev)->
5636                                                 limits.discard_zeroes_data)
5637                                 discard_supported = false;
5638                 }
5639
5640                 if (discard_supported &&
5641                    mddev->queue->limits.max_discard_sectors >= stripe &&
5642                    mddev->queue->limits.discard_granularity >= stripe)
5643                         queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
5644                                                 mddev->queue);
5645                 else
5646                         queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD,
5647                                                 mddev->queue);
5648         }
5649
5650         return 0;
5651 abort:
5652         md_unregister_thread(&mddev->thread);
5653         print_raid5_conf(conf);
5654         free_conf(conf);
5655         mddev->private = NULL;
5656         printk(KERN_ALERT "md/raid:%s: failed to run raid set.\n", mdname(mddev));
5657         return -EIO;
5658 }
5659
5660 static int stop(struct mddev *mddev)
5661 {
5662         struct r5conf *conf = mddev->private;
5663
5664         md_unregister_thread(&mddev->thread);
5665         if (mddev->queue)
5666                 mddev->queue->backing_dev_info.congested_fn = NULL;
5667         free_conf(conf);
5668         mddev->private = NULL;
5669         mddev->to_remove = &raid5_attrs_group;
5670         return 0;
5671 }
5672
5673 static void status(struct seq_file *seq, struct mddev *mddev)
5674 {
5675         struct r5conf *conf = mddev->private;
5676         int i;
5677
5678         seq_printf(seq, " level %d, %dk chunk, algorithm %d", mddev->level,
5679                 mddev->chunk_sectors / 2, mddev->layout);
5680         seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded);
5681         for (i = 0; i < conf->raid_disks; i++)
5682                 seq_printf (seq, "%s",
5683                                conf->disks[i].rdev &&
5684                                test_bit(In_sync, &conf->disks[i].rdev->flags) ? "U" : "_");
5685         seq_printf (seq, "]");
5686 }
5687
5688 static void print_raid5_conf (struct r5conf *conf)
5689 {
5690         int i;
5691         struct disk_info *tmp;
5692
5693         printk(KERN_DEBUG "RAID conf printout:\n");
5694         if (!conf) {
5695                 printk("(conf==NULL)\n");
5696                 return;
5697         }
5698         printk(KERN_DEBUG " --- level:%d rd:%d wd:%d\n", conf->level,
5699                conf->raid_disks,
5700                conf->raid_disks - conf->mddev->degraded);
5701
5702         for (i = 0; i < conf->raid_disks; i++) {
5703                 char b[BDEVNAME_SIZE];
5704                 tmp = conf->disks + i;
5705                 if (tmp->rdev)
5706                         printk(KERN_DEBUG " disk %d, o:%d, dev:%s\n",
5707                                i, !test_bit(Faulty, &tmp->rdev->flags),
5708                                bdevname(tmp->rdev->bdev, b));
5709         }
5710 }
5711
5712 static int raid5_spare_active(struct mddev *mddev)
5713 {
5714         int i;
5715         struct r5conf *conf = mddev->private;
5716         struct disk_info *tmp;
5717         int count = 0;
5718         unsigned long flags;
5719
5720         for (i = 0; i < conf->raid_disks; i++) {
5721                 tmp = conf->disks + i;
5722                 if (tmp->replacement
5723                     && tmp->replacement->recovery_offset == MaxSector
5724                     && !test_bit(Faulty, &tmp->replacement->flags)
5725                     && !test_and_set_bit(In_sync, &tmp->replacement->flags)) {
5726                         /* Replacement has just become active. */
5727                         if (!tmp->rdev
5728                             || !test_and_clear_bit(In_sync, &tmp->rdev->flags))
5729                                 count++;
5730                         if (tmp->rdev) {
5731                                 /* Replaced device not technically faulty,
5732                                  * but we need to be sure it gets removed
5733                                  * and never re-added.
5734                                  */
5735                                 set_bit(Faulty, &tmp->rdev->flags);
5736                                 sysfs_notify_dirent_safe(
5737                                         tmp->rdev->sysfs_state);
5738                         }
5739                         sysfs_notify_dirent_safe(tmp->replacement->sysfs_state);
5740                 } else if (tmp->rdev
5741                     && tmp->rdev->recovery_offset == MaxSector
5742                     && !test_bit(Faulty, &tmp->rdev->flags)
5743                     && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
5744                         count++;
5745                         sysfs_notify_dirent_safe(tmp->rdev->sysfs_state);
5746                 }
5747         }
5748         spin_lock_irqsave(&conf->device_lock, flags);
5749         mddev->degraded = calc_degraded(conf);
5750         spin_unlock_irqrestore(&conf->device_lock, flags);
5751         print_raid5_conf(conf);
5752         return count;
5753 }
5754
5755 static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
5756 {
5757         struct r5conf *conf = mddev->private;
5758         int err = 0;
5759         int number = rdev->raid_disk;
5760         struct md_rdev **rdevp;
5761         struct disk_info *p = conf->disks + number;
5762
5763         print_raid5_conf(conf);
5764         if (rdev == p->rdev)
5765                 rdevp = &p->rdev;
5766         else if (rdev == p->replacement)
5767                 rdevp = &p->replacement;
5768         else
5769                 return 0;
5770
5771         if (number >= conf->raid_disks &&
5772             conf->reshape_progress == MaxSector)
5773                 clear_bit(In_sync, &rdev->flags);
5774
5775         if (test_bit(In_sync, &rdev->flags) ||
5776             atomic_read(&rdev->nr_pending)) {
5777                 err = -EBUSY;
5778                 goto abort;
5779         }
5780         /* Only remove non-faulty devices if recovery
5781          * isn't possible.
5782          */
5783         if (!test_bit(Faulty, &rdev->flags) &&
5784             mddev->recovery_disabled != conf->recovery_disabled &&
5785             !has_failed(conf) &&
5786             (!p->replacement || p->replacement == rdev) &&
5787             number < conf->raid_disks) {
5788                 err = -EBUSY;
5789                 goto abort;
5790         }
5791         *rdevp = NULL;
5792         synchronize_rcu();
5793         if (atomic_read(&rdev->nr_pending)) {
5794                 /* lost the race, try later */
5795                 err = -EBUSY;
5796                 *rdevp = rdev;
5797         } else if (p->replacement) {
5798                 /* We must have just cleared 'rdev' */
5799                 p->rdev = p->replacement;
5800                 clear_bit(Replacement, &p->replacement->flags);
5801                 smp_mb(); /* Make sure other CPUs may see both as identical
5802                            * but will never see neither - if they are careful
5803                            */
5804                 p->replacement = NULL;
5805                 clear_bit(WantReplacement, &rdev->flags);
5806         } else
5807                 /* We might have just removed the Replacement as faulty-
5808                  * clear the bit just in case
5809                  */
5810                 clear_bit(WantReplacement, &rdev->flags);
5811 abort:
5812
5813         print_raid5_conf(conf);
5814         return err;
5815 }
5816
5817 static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
5818 {
5819         struct r5conf *conf = mddev->private;
5820         int err = -EEXIST;
5821         int disk;
5822         struct disk_info *p;
5823         int first = 0;
5824         int last = conf->raid_disks - 1;
5825
5826         if (mddev->recovery_disabled == conf->recovery_disabled)
5827                 return -EBUSY;
5828
5829         if (rdev->saved_raid_disk < 0 && has_failed(conf))
5830                 /* no point adding a device */
5831                 return -EINVAL;
5832
5833         if (rdev->raid_disk >= 0)
5834                 first = last = rdev->raid_disk;
5835
5836         /*
5837          * find the disk ... but prefer rdev->saved_raid_disk
5838          * if possible.
5839          */
5840         if (rdev->saved_raid_disk >= 0 &&
5841             rdev->saved_raid_disk >= first &&
5842             conf->disks[rdev->saved_raid_disk].rdev == NULL)
5843                 first = rdev->saved_raid_disk;
5844
5845         for (disk = first; disk <= last; disk++) {
5846                 p = conf->disks + disk;
5847                 if (p->rdev == NULL) {
5848                         clear_bit(In_sync, &rdev->flags);
5849                         rdev->raid_disk = disk;
5850                         err = 0;
5851                         if (rdev->saved_raid_disk != disk)
5852                                 conf->fullsync = 1;
5853                         rcu_assign_pointer(p->rdev, rdev);
5854                         goto out;
5855                 }
5856         }
5857         for (disk = first; disk <= last; disk++) {
5858                 p = conf->disks + disk;
5859                 if (test_bit(WantReplacement, &p->rdev->flags) &&
5860                     p->replacement == NULL) {
5861                         clear_bit(In_sync, &rdev->flags);
5862                         set_bit(Replacement, &rdev->flags);
5863                         rdev->raid_disk = disk;
5864                         err = 0;
5865                         conf->fullsync = 1;
5866                         rcu_assign_pointer(p->replacement, rdev);
5867                         break;
5868                 }
5869         }
5870 out:
5871         print_raid5_conf(conf);
5872         return err;
5873 }
5874
5875 static int raid5_resize(struct mddev *mddev, sector_t sectors)
5876 {
5877         /* no resync is happening, and there is enough space
5878          * on all devices, so we can resize.
5879          * We need to make sure resync covers any new space.
5880          * If the array is shrinking we should possibly wait until
5881          * any io in the removed space completes, but it hardly seems
5882          * worth it.
5883          */
5884         sector_t newsize;
5885         sectors &= ~((sector_t)mddev->chunk_sectors - 1);
5886         newsize = raid5_size(mddev, sectors, mddev->raid_disks);
5887         if (mddev->external_size &&
5888             mddev->array_sectors > newsize)
5889                 return -EINVAL;
5890         if (mddev->bitmap) {
5891                 int ret = bitmap_resize(mddev->bitmap, sectors, 0, 0);
5892                 if (ret)
5893                         return ret;
5894         }
5895         md_set_array_sectors(mddev, newsize);
5896         set_capacity(mddev->gendisk, mddev->array_sectors);
5897         revalidate_disk(mddev->gendisk);
5898         if (sectors > mddev->dev_sectors &&
5899             mddev->recovery_cp > mddev->dev_sectors) {
5900                 mddev->recovery_cp = mddev->dev_sectors;
5901                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
5902         }
5903         mddev->dev_sectors = sectors;
5904         mddev->resync_max_sectors = sectors;
5905         return 0;
5906 }
5907
5908 static int check_stripe_cache(struct mddev *mddev)
5909 {
5910         /* Can only proceed if there are plenty of stripe_heads.
5911          * We need a minimum of one full stripe,, and for sensible progress
5912          * it is best to have about 4 times that.
5913          * If we require 4 times, then the default 256 4K stripe_heads will
5914          * allow for chunk sizes up to 256K, which is probably OK.
5915          * If the chunk size is greater, user-space should request more
5916          * stripe_heads first.
5917          */
5918         struct r5conf *conf = mddev->private;
5919         if (((mddev->chunk_sectors << 9) / STRIPE_SIZE) * 4
5920             > conf->max_nr_stripes ||
5921             ((mddev->new_chunk_sectors << 9) / STRIPE_SIZE) * 4
5922             > conf->max_nr_stripes) {
5923                 printk(KERN_WARNING "md/raid:%s: reshape: not enough stripes.  Needed %lu\n",
5924                        mdname(mddev),
5925                        ((max(mddev->chunk_sectors, mddev->new_chunk_sectors) << 9)
5926                         / STRIPE_SIZE)*4);
5927                 return 0;
5928         }
5929         return 1;
5930 }
5931
5932 static int check_reshape(struct mddev *mddev)
5933 {
5934         struct r5conf *conf = mddev->private;
5935
5936         if (mddev->delta_disks == 0 &&
5937             mddev->new_layout == mddev->layout &&
5938             mddev->new_chunk_sectors == mddev->chunk_sectors)
5939                 return 0; /* nothing to do */
5940         if (has_failed(conf))
5941                 return -EINVAL;
5942         if (mddev->delta_disks < 0) {
5943                 /* We might be able to shrink, but the devices must
5944                  * be made bigger first.
5945                  * For raid6, 4 is the minimum size.
5946                  * Otherwise 2 is the minimum
5947                  */
5948                 int min = 2;
5949                 if (mddev->level == 6)
5950                         min = 4;
5951                 if (mddev->raid_disks + mddev->delta_disks < min)
5952                         return -EINVAL;
5953         }
5954
5955         if (!check_stripe_cache(mddev))
5956                 return -ENOSPC;
5957
5958         return resize_stripes(conf, (conf->previous_raid_disks
5959                                      + mddev->delta_disks));
5960 }
5961
5962 static int raid5_start_reshape(struct mddev *mddev)
5963 {
5964         struct r5conf *conf = mddev->private;
5965         struct md_rdev *rdev;
5966         int spares = 0;
5967         unsigned long flags;
5968
5969         if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
5970                 return -EBUSY;
5971
5972         if (!check_stripe_cache(mddev))
5973                 return -ENOSPC;
5974
5975         if (has_failed(conf))
5976                 return -EINVAL;
5977
5978         rdev_for_each(rdev, mddev) {
5979                 if (!test_bit(In_sync, &rdev->flags)
5980                     && !test_bit(Faulty, &rdev->flags))
5981                         spares++;
5982         }
5983
5984         if (spares - mddev->degraded < mddev->delta_disks - conf->max_degraded)
5985                 /* Not enough devices even to make a degraded array
5986                  * of that size
5987                  */
5988                 return -EINVAL;
5989
5990         /* Refuse to reduce size of the array.  Any reductions in
5991          * array size must be through explicit setting of array_size
5992          * attribute.
5993          */
5994         if (raid5_size(mddev, 0, conf->raid_disks + mddev->delta_disks)
5995             < mddev->array_sectors) {
5996                 printk(KERN_ERR "md/raid:%s: array size must be reduced "
5997                        "before number of disks\n", mdname(mddev));
5998                 return -EINVAL;
5999         }
6000
6001         atomic_set(&conf->reshape_stripes, 0);
6002         spin_lock_irq(&conf->device_lock);
6003         conf->previous_raid_disks = conf->raid_disks;
6004         conf->raid_disks += mddev->delta_disks;
6005         conf->prev_chunk_sectors = conf->chunk_sectors;
6006         conf->chunk_sectors = mddev->new_chunk_sectors;
6007         conf->prev_algo = conf->algorithm;
6008         conf->algorithm = mddev->new_layout;
6009         conf->generation++;
6010         /* Code that selects data_offset needs to see the generation update
6011          * if reshape_progress has been set - so a memory barrier needed.
6012          */
6013         smp_mb();
6014         if (mddev->reshape_backwards)
6015                 conf->reshape_progress = raid5_size(mddev, 0, 0);
6016         else
6017                 conf->reshape_progress = 0;
6018         conf->reshape_safe = conf->reshape_progress;
6019         spin_unlock_irq(&conf->device_lock);
6020
6021         /* Add some new drives, as many as will fit.
6022          * We know there are enough to make the newly sized array work.
6023          * Don't add devices if we are reducing the number of
6024          * devices in the array.  This is because it is not possible
6025          * to correctly record the "partially reconstructed" state of
6026          * such devices during the reshape and confusion could result.
6027          */
6028         if (mddev->delta_disks >= 0) {
6029                 rdev_for_each(rdev, mddev)
6030                         if (rdev->raid_disk < 0 &&
6031                             !test_bit(Faulty, &rdev->flags)) {
6032                                 if (raid5_add_disk(mddev, rdev) == 0) {
6033                                         if (rdev->raid_disk
6034                                             >= conf->previous_raid_disks)
6035                                                 set_bit(In_sync, &rdev->flags);
6036                                         else
6037                                                 rdev->recovery_offset = 0;
6038
6039                                         if (sysfs_link_rdev(mddev, rdev))
6040                                                 /* Failure here is OK */;
6041                                 }
6042                         } else if (rdev->raid_disk >= conf->previous_raid_disks
6043                                    && !test_bit(Faulty, &rdev->flags)) {
6044                                 /* This is a spare that was manually added */
6045                                 set_bit(In_sync, &rdev->flags);
6046                         }
6047
6048                 /* When a reshape changes the number of devices,
6049                  * ->degraded is measured against the larger of the
6050                  * pre and post number of devices.
6051                  */
6052                 spin_lock_irqsave(&conf->device_lock, flags);
6053                 mddev->degraded = calc_degraded(conf);
6054                 spin_unlock_irqrestore(&conf->device_lock, flags);
6055         }
6056         mddev->raid_disks = conf->raid_disks;
6057         mddev->reshape_position = conf->reshape_progress;
6058         set_bit(MD_CHANGE_DEVS, &mddev->flags);
6059
6060         clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
6061         clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
6062         set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
6063         set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
6064         mddev->sync_thread = md_register_thread(md_do_sync, mddev,
6065                                                 "reshape");
6066         if (!mddev->sync_thread) {
6067                 mddev->recovery = 0;
6068                 spin_lock_irq(&conf->device_lock);
6069                 mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
6070                 rdev_for_each(rdev, mddev)
6071                         rdev->new_data_offset = rdev->data_offset;
6072                 smp_wmb();
6073                 conf->reshape_progress = MaxSector;
6074                 mddev->reshape_position = MaxSector;
6075                 spin_unlock_irq(&conf->device_lock);
6076                 return -EAGAIN;
6077         }
6078         conf->reshape_checkpoint = jiffies;
6079         md_wakeup_thread(mddev->sync_thread);
6080         md_new_event(mddev);
6081         return 0;
6082 }
6083
6084 /* This is called from the reshape thread and should make any
6085  * changes needed in 'conf'
6086  */
6087 static void end_reshape(struct r5conf *conf)
6088 {
6089
6090         if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
6091                 struct md_rdev *rdev;
6092
6093                 spin_lock_irq(&conf->device_lock);
6094                 conf->previous_raid_disks = conf->raid_disks;
6095                 rdev_for_each(rdev, conf->mddev)
6096                         rdev->data_offset = rdev->new_data_offset;
6097                 smp_wmb();
6098                 conf->reshape_progress = MaxSector;
6099                 spin_unlock_irq(&conf->device_lock);
6100                 wake_up(&conf->wait_for_overlap);
6101
6102                 /* read-ahead size must cover two whole stripes, which is
6103                  * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
6104                  */
6105                 if (conf->mddev->queue) {
6106                         int data_disks = conf->raid_disks - conf->max_degraded;
6107                         int stripe = data_disks * ((conf->chunk_sectors << 9)
6108                                                    / PAGE_SIZE);
6109                         if (conf->mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
6110                                 conf->mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
6111                 }
6112         }
6113 }
6114
6115 /* This is called from the raid5d thread with mddev_lock held.
6116  * It makes config changes to the device.
6117  */
6118 static void raid5_finish_reshape(struct mddev *mddev)
6119 {
6120         struct r5conf *conf = mddev->private;
6121
6122         if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
6123
6124                 if (mddev->delta_disks > 0) {
6125                         md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
6126                         set_capacity(mddev->gendisk, mddev->array_sectors);
6127                         revalidate_disk(mddev->gendisk);
6128                 } else {
6129                         int d;
6130                         spin_lock_irq(&conf->device_lock);
6131                         mddev->degraded = calc_degraded(conf);
6132                         spin_unlock_irq(&conf->device_lock);
6133                         for (d = conf->raid_disks ;
6134                              d < conf->raid_disks - mddev->delta_disks;
6135                              d++) {
6136                                 struct md_rdev *rdev = conf->disks[d].rdev;
6137                                 if (rdev)
6138                                         clear_bit(In_sync, &rdev->flags);
6139                                 rdev = conf->disks[d].replacement;
6140                                 if (rdev)
6141                                         clear_bit(In_sync, &rdev->flags);
6142                         }
6143                 }
6144                 mddev->layout = conf->algorithm;
6145                 mddev->chunk_sectors = conf->chunk_sectors;
6146                 mddev->reshape_position = MaxSector;
6147                 mddev->delta_disks = 0;
6148                 mddev->reshape_backwards = 0;
6149         }
6150 }
6151
6152 static void raid5_quiesce(struct mddev *mddev, int state)
6153 {
6154         struct r5conf *conf = mddev->private;
6155
6156         switch(state) {
6157         case 2: /* resume for a suspend */
6158                 wake_up(&conf->wait_for_overlap);
6159                 break;
6160
6161         case 1: /* stop all writes */
6162                 spin_lock_irq(&conf->device_lock);
6163                 /* '2' tells resync/reshape to pause so that all
6164                  * active stripes can drain
6165                  */
6166                 conf->quiesce = 2;
6167                 wait_event_lock_irq(conf->wait_for_stripe,
6168                                     atomic_read(&conf->active_stripes) == 0 &&
6169                                     atomic_read(&conf->active_aligned_reads) == 0,
6170                                     conf->device_lock);
6171                 conf->quiesce = 1;
6172                 spin_unlock_irq(&conf->device_lock);
6173                 /* allow reshape to continue */
6174                 wake_up(&conf->wait_for_overlap);
6175                 break;
6176
6177         case 0: /* re-enable writes */
6178                 spin_lock_irq(&conf->device_lock);
6179                 conf->quiesce = 0;
6180                 wake_up(&conf->wait_for_stripe);
6181                 wake_up(&conf->wait_for_overlap);
6182                 spin_unlock_irq(&conf->device_lock);
6183                 break;
6184         }
6185 }
6186
6187
6188 static void *raid45_takeover_raid0(struct mddev *mddev, int level)
6189 {
6190         struct r0conf *raid0_conf = mddev->private;
6191         sector_t sectors;
6192
6193         /* for raid0 takeover only one zone is supported */
6194         if (raid0_conf->nr_strip_zones > 1) {
6195                 printk(KERN_ERR "md/raid:%s: cannot takeover raid0 with more than one zone.\n",
6196                        mdname(mddev));
6197                 return ERR_PTR(-EINVAL);
6198         }
6199
6200         sectors = raid0_conf->strip_zone[0].zone_end;
6201         sector_div(sectors, raid0_conf->strip_zone[0].nb_dev);
6202         mddev->dev_sectors = sectors;
6203         mddev->new_level = level;
6204         mddev->new_layout = ALGORITHM_PARITY_N;
6205         mddev->new_chunk_sectors = mddev->chunk_sectors;
6206         mddev->raid_disks += 1;
6207         mddev->delta_disks = 1;
6208         /* make sure it will be not marked as dirty */
6209         mddev->recovery_cp = MaxSector;
6210
6211         return setup_conf(mddev);
6212 }
6213
6214
6215 static void *raid5_takeover_raid1(struct mddev *mddev)
6216 {
6217         int chunksect;
6218
6219         if (mddev->raid_disks != 2 ||
6220             mddev->degraded > 1)
6221                 return ERR_PTR(-EINVAL);
6222
6223         /* Should check if there are write-behind devices? */
6224
6225         chunksect = 64*2; /* 64K by default */
6226
6227         /* The array must be an exact multiple of chunksize */
6228         while (chunksect && (mddev->array_sectors & (chunksect-1)))
6229                 chunksect >>= 1;
6230
6231         if ((chunksect<<9) < STRIPE_SIZE)
6232                 /* array size does not allow a suitable chunk size */
6233                 return ERR_PTR(-EINVAL);
6234
6235         mddev->new_level = 5;
6236         mddev->new_layout = ALGORITHM_LEFT_SYMMETRIC;
6237         mddev->new_chunk_sectors = chunksect;
6238
6239         return setup_conf(mddev);
6240 }
6241
6242 static void *raid5_takeover_raid6(struct mddev *mddev)
6243 {
6244         int new_layout;
6245
6246         switch (mddev->layout) {
6247         case ALGORITHM_LEFT_ASYMMETRIC_6:
6248                 new_layout = ALGORITHM_LEFT_ASYMMETRIC;
6249                 break;
6250         case ALGORITHM_RIGHT_ASYMMETRIC_6:
6251                 new_layout = ALGORITHM_RIGHT_ASYMMETRIC;
6252                 break;
6253         case ALGORITHM_LEFT_SYMMETRIC_6:
6254                 new_layout = ALGORITHM_LEFT_SYMMETRIC;
6255                 break;
6256         case ALGORITHM_RIGHT_SYMMETRIC_6:
6257                 new_layout = ALGORITHM_RIGHT_SYMMETRIC;
6258                 break;
6259         case ALGORITHM_PARITY_0_6:
6260                 new_layout = ALGORITHM_PARITY_0;
6261                 break;
6262         case ALGORITHM_PARITY_N:
6263                 new_layout = ALGORITHM_PARITY_N;
6264                 break;
6265         default:
6266                 return ERR_PTR(-EINVAL);
6267         }
6268         mddev->new_level = 5;
6269         mddev->new_layout = new_layout;
6270         mddev->delta_disks = -1;
6271         mddev->raid_disks -= 1;
6272         return setup_conf(mddev);
6273 }
6274
6275
6276 static int raid5_check_reshape(struct mddev *mddev)
6277 {
6278         /* For a 2-drive array, the layout and chunk size can be changed
6279          * immediately as not restriping is needed.
6280          * For larger arrays we record the new value - after validation
6281          * to be used by a reshape pass.
6282          */
6283         struct r5conf *conf = mddev->private;
6284         int new_chunk = mddev->new_chunk_sectors;
6285
6286         if (mddev->new_layout >= 0 && !algorithm_valid_raid5(mddev->new_layout))
6287                 return -EINVAL;
6288         if (new_chunk > 0) {
6289                 if (!is_power_of_2(new_chunk))
6290                         return -EINVAL;
6291                 if (new_chunk < (PAGE_SIZE>>9))
6292                         return -EINVAL;
6293                 if (mddev->array_sectors & (new_chunk-1))
6294                         /* not factor of array size */
6295                         return -EINVAL;
6296         }
6297
6298         /* They look valid */
6299
6300         if (mddev->raid_disks == 2) {
6301                 /* can make the change immediately */
6302                 if (mddev->new_layout >= 0) {
6303                         conf->algorithm = mddev->new_layout;
6304                         mddev->layout = mddev->new_layout;
6305                 }
6306                 if (new_chunk > 0) {
6307                         conf->chunk_sectors = new_chunk ;
6308                         mddev->chunk_sectors = new_chunk;
6309                 }
6310                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
6311                 md_wakeup_thread(mddev->thread);
6312         }
6313         return check_reshape(mddev);
6314 }
6315
6316 static int raid6_check_reshape(struct mddev *mddev)
6317 {
6318         int new_chunk = mddev->new_chunk_sectors;
6319
6320         if (mddev->new_layout >= 0 && !algorithm_valid_raid6(mddev->new_layout))
6321                 return -EINVAL;
6322         if (new_chunk > 0) {
6323                 if (!is_power_of_2(new_chunk))
6324                         return -EINVAL;
6325                 if (new_chunk < (PAGE_SIZE >> 9))
6326                         return -EINVAL;
6327                 if (mddev->array_sectors & (new_chunk-1))
6328                         /* not factor of array size */
6329                         return -EINVAL;
6330         }
6331
6332         /* They look valid */
6333         return check_reshape(mddev);
6334 }
6335
6336 static void *raid5_takeover(struct mddev *mddev)
6337 {
6338         /* raid5 can take over:
6339          *  raid0 - if there is only one strip zone - make it a raid4 layout
6340          *  raid1 - if there are two drives.  We need to know the chunk size
6341          *  raid4 - trivial - just use a raid4 layout.
6342          *  raid6 - Providing it is a *_6 layout
6343          */
6344         if (mddev->level == 0)
6345                 return raid45_takeover_raid0(mddev, 5);
6346         if (mddev->level == 1)
6347                 return raid5_takeover_raid1(mddev);
6348         if (mddev->level == 4) {
6349                 mddev->new_layout = ALGORITHM_PARITY_N;
6350                 mddev->new_level = 5;
6351                 return setup_conf(mddev);
6352         }
6353         if (mddev->level == 6)
6354                 return raid5_takeover_raid6(mddev);
6355
6356         return ERR_PTR(-EINVAL);
6357 }
6358
6359 static void *raid4_takeover(struct mddev *mddev)
6360 {
6361         /* raid4 can take over:
6362          *  raid0 - if there is only one strip zone
6363          *  raid5 - if layout is right
6364          */
6365         if (mddev->level == 0)
6366                 return raid45_takeover_raid0(mddev, 4);
6367         if (mddev->level == 5 &&
6368             mddev->layout == ALGORITHM_PARITY_N) {
6369                 mddev->new_layout = 0;
6370                 mddev->new_level = 4;
6371                 return setup_conf(mddev);
6372         }
6373         return ERR_PTR(-EINVAL);
6374 }
6375
6376 static struct md_personality raid5_personality;
6377
6378 static void *raid6_takeover(struct mddev *mddev)
6379 {
6380         /* Currently can only take over a raid5.  We map the
6381          * personality to an equivalent raid6 personality
6382          * with the Q block at the end.
6383          */
6384         int new_layout;
6385
6386         if (mddev->pers != &raid5_personality)
6387                 return ERR_PTR(-EINVAL);
6388         if (mddev->degraded > 1)
6389                 return ERR_PTR(-EINVAL);
6390         if (mddev->raid_disks > 253)
6391                 return ERR_PTR(-EINVAL);
6392         if (mddev->raid_disks < 3)
6393                 return ERR_PTR(-EINVAL);
6394
6395         switch (mddev->layout) {
6396         case ALGORITHM_LEFT_ASYMMETRIC:
6397                 new_layout = ALGORITHM_LEFT_ASYMMETRIC_6;
6398                 break;
6399         case ALGORITHM_RIGHT_ASYMMETRIC:
6400                 new_layout = ALGORITHM_RIGHT_ASYMMETRIC_6;
6401                 break;
6402         case ALGORITHM_LEFT_SYMMETRIC:
6403                 new_layout = ALGORITHM_LEFT_SYMMETRIC_6;
6404                 break;
6405         case ALGORITHM_RIGHT_SYMMETRIC:
6406                 new_layout = ALGORITHM_RIGHT_SYMMETRIC_6;
6407                 break;
6408         case ALGORITHM_PARITY_0:
6409                 new_layout = ALGORITHM_PARITY_0_6;
6410                 break;
6411         case ALGORITHM_PARITY_N:
6412                 new_layout = ALGORITHM_PARITY_N;
6413                 break;
6414         default:
6415                 return ERR_PTR(-EINVAL);
6416         }
6417         mddev->new_level = 6;
6418         mddev->new_layout = new_layout;
6419         mddev->delta_disks = 1;
6420         mddev->raid_disks += 1;
6421         return setup_conf(mddev);
6422 }
6423
6424
6425 static struct md_personality raid6_personality =
6426 {
6427         .name           = "raid6",
6428         .level          = 6,
6429         .owner          = THIS_MODULE,
6430         .make_request   = make_request,
6431         .run            = run,
6432         .stop           = stop,
6433         .status         = status,
6434         .error_handler  = error,
6435         .hot_add_disk   = raid5_add_disk,
6436         .hot_remove_disk= raid5_remove_disk,
6437         .spare_active   = raid5_spare_active,
6438         .sync_request   = sync_request,
6439         .resize         = raid5_resize,
6440         .size           = raid5_size,
6441         .check_reshape  = raid6_check_reshape,
6442         .start_reshape  = raid5_start_reshape,
6443         .finish_reshape = raid5_finish_reshape,
6444         .quiesce        = raid5_quiesce,
6445         .takeover       = raid6_takeover,
6446 };
6447 static struct md_personality raid5_personality =
6448 {
6449         .name           = "raid5",
6450         .level          = 5,
6451         .owner          = THIS_MODULE,
6452         .make_request   = make_request,
6453         .run            = run,
6454         .stop           = stop,
6455         .status         = status,
6456         .error_handler  = error,
6457         .hot_add_disk   = raid5_add_disk,
6458         .hot_remove_disk= raid5_remove_disk,
6459         .spare_active   = raid5_spare_active,
6460         .sync_request   = sync_request,
6461         .resize         = raid5_resize,
6462         .size           = raid5_size,
6463         .check_reshape  = raid5_check_reshape,
6464         .start_reshape  = raid5_start_reshape,
6465         .finish_reshape = raid5_finish_reshape,
6466         .quiesce        = raid5_quiesce,
6467         .takeover       = raid5_takeover,
6468 };
6469
6470 static struct md_personality raid4_personality =
6471 {
6472         .name           = "raid4",
6473         .level          = 4,
6474         .owner          = THIS_MODULE,
6475         .make_request   = make_request,
6476         .run            = run,
6477         .stop           = stop,
6478         .status         = status,
6479         .error_handler  = error,
6480         .hot_add_disk   = raid5_add_disk,
6481         .hot_remove_disk= raid5_remove_disk,
6482         .spare_active   = raid5_spare_active,
6483         .sync_request   = sync_request,
6484         .resize         = raid5_resize,
6485         .size           = raid5_size,
6486         .check_reshape  = raid5_check_reshape,
6487         .start_reshape  = raid5_start_reshape,
6488         .finish_reshape = raid5_finish_reshape,
6489         .quiesce        = raid5_quiesce,
6490         .takeover       = raid4_takeover,
6491 };
6492
6493 static int __init raid5_init(void)
6494 {
6495         register_md_personality(&raid6_personality);
6496         register_md_personality(&raid5_personality);
6497         register_md_personality(&raid4_personality);
6498         return 0;
6499 }
6500
6501 static void raid5_exit(void)
6502 {
6503         unregister_md_personality(&raid6_personality);
6504         unregister_md_personality(&raid5_personality);
6505         unregister_md_personality(&raid4_personality);
6506 }
6507
6508 module_init(raid5_init);
6509 module_exit(raid5_exit);
6510 MODULE_LICENSE("GPL");
6511 MODULE_DESCRIPTION("RAID4/5/6 (striping with parity) personality for MD");
6512 MODULE_ALIAS("md-personality-4"); /* RAID5 */
6513 MODULE_ALIAS("md-raid5");
6514 MODULE_ALIAS("md-raid4");
6515 MODULE_ALIAS("md-level-5");
6516 MODULE_ALIAS("md-level-4");
6517 MODULE_ALIAS("md-personality-8"); /* RAID6 */
6518 MODULE_ALIAS("md-raid6");
6519 MODULE_ALIAS("md-level-6");
6520
6521 /* This used to be two separate modules, they were: */
6522 MODULE_ALIAS("raid5");
6523 MODULE_ALIAS("raid6");