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(STRIPE_DEGRADED, &sh->state);
1897                         set_bit(WriteErrorSeen, &rdev->flags);
1898                         set_bit(R5_WriteError, &sh->dev[i].flags);
1899                         if (!test_and_set_bit(WantReplacement, &rdev->flags))
1900                                 set_bit(MD_RECOVERY_NEEDED,
1901                                         &rdev->mddev->recovery);
1902                 } else if (is_badblock(rdev, sh->sector,
1903                                        STRIPE_SECTORS,
1904                                        &first_bad, &bad_sectors)) {
1905                         set_bit(R5_MadeGood, &sh->dev[i].flags);
1906                         if (test_bit(R5_ReadError, &sh->dev[i].flags))
1907                                 /* That was a successful write so make
1908                                  * sure it looks like we already did
1909                                  * a re-write.
1910                                  */
1911                                 set_bit(R5_ReWrite, &sh->dev[i].flags);
1912                 }
1913         }
1914         rdev_dec_pending(rdev, conf->mddev);
1915
1916         if (!test_and_clear_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags))
1917                 clear_bit(R5_LOCKED, &sh->dev[i].flags);
1918         set_bit(STRIPE_HANDLE, &sh->state);
1919         release_stripe(sh);
1920 }
1921
1922 static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous);
1923
1924 static void raid5_build_block(struct stripe_head *sh, int i, int previous)
1925 {
1926         struct r5dev *dev = &sh->dev[i];
1927
1928         bio_init(&dev->req);
1929         dev->req.bi_io_vec = &dev->vec;
1930         dev->req.bi_vcnt++;
1931         dev->req.bi_max_vecs++;
1932         dev->req.bi_private = sh;
1933         dev->vec.bv_page = dev->page;
1934
1935         bio_init(&dev->rreq);
1936         dev->rreq.bi_io_vec = &dev->rvec;
1937         dev->rreq.bi_vcnt++;
1938         dev->rreq.bi_max_vecs++;
1939         dev->rreq.bi_private = sh;
1940         dev->rvec.bv_page = dev->page;
1941
1942         dev->flags = 0;
1943         dev->sector = compute_blocknr(sh, i, previous);
1944 }
1945
1946 static void error(struct mddev *mddev, struct md_rdev *rdev)
1947 {
1948         char b[BDEVNAME_SIZE];
1949         struct r5conf *conf = mddev->private;
1950         unsigned long flags;
1951         pr_debug("raid456: error called\n");
1952
1953         spin_lock_irqsave(&conf->device_lock, flags);
1954         clear_bit(In_sync, &rdev->flags);
1955         mddev->degraded = calc_degraded(conf);
1956         spin_unlock_irqrestore(&conf->device_lock, flags);
1957         set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1958
1959         set_bit(Blocked, &rdev->flags);
1960         set_bit(Faulty, &rdev->flags);
1961         set_bit(MD_CHANGE_DEVS, &mddev->flags);
1962         printk(KERN_ALERT
1963                "md/raid:%s: Disk failure on %s, disabling device.\n"
1964                "md/raid:%s: Operation continuing on %d devices.\n",
1965                mdname(mddev),
1966                bdevname(rdev->bdev, b),
1967                mdname(mddev),
1968                conf->raid_disks - mddev->degraded);
1969 }
1970
1971 /*
1972  * Input: a 'big' sector number,
1973  * Output: index of the data and parity disk, and the sector # in them.
1974  */
1975 static sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
1976                                      int previous, int *dd_idx,
1977                                      struct stripe_head *sh)
1978 {
1979         sector_t stripe, stripe2;
1980         sector_t chunk_number;
1981         unsigned int chunk_offset;
1982         int pd_idx, qd_idx;
1983         int ddf_layout = 0;
1984         sector_t new_sector;
1985         int algorithm = previous ? conf->prev_algo
1986                                  : conf->algorithm;
1987         int sectors_per_chunk = previous ? conf->prev_chunk_sectors
1988                                          : conf->chunk_sectors;
1989         int raid_disks = previous ? conf->previous_raid_disks
1990                                   : conf->raid_disks;
1991         int data_disks = raid_disks - conf->max_degraded;
1992
1993         /* First compute the information on this sector */
1994
1995         /*
1996          * Compute the chunk number and the sector offset inside the chunk
1997          */
1998         chunk_offset = sector_div(r_sector, sectors_per_chunk);
1999         chunk_number = r_sector;
2000
2001         /*
2002          * Compute the stripe number
2003          */
2004         stripe = chunk_number;
2005         *dd_idx = sector_div(stripe, data_disks);
2006         stripe2 = stripe;
2007         /*
2008          * Select the parity disk based on the user selected algorithm.
2009          */
2010         pd_idx = qd_idx = -1;
2011         switch(conf->level) {
2012         case 4:
2013                 pd_idx = data_disks;
2014                 break;
2015         case 5:
2016                 switch (algorithm) {
2017                 case ALGORITHM_LEFT_ASYMMETRIC:
2018                         pd_idx = data_disks - sector_div(stripe2, raid_disks);
2019                         if (*dd_idx >= pd_idx)
2020                                 (*dd_idx)++;
2021                         break;
2022                 case ALGORITHM_RIGHT_ASYMMETRIC:
2023                         pd_idx = sector_div(stripe2, raid_disks);
2024                         if (*dd_idx >= pd_idx)
2025                                 (*dd_idx)++;
2026                         break;
2027                 case ALGORITHM_LEFT_SYMMETRIC:
2028                         pd_idx = data_disks - sector_div(stripe2, raid_disks);
2029                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2030                         break;
2031                 case ALGORITHM_RIGHT_SYMMETRIC:
2032                         pd_idx = sector_div(stripe2, raid_disks);
2033                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2034                         break;
2035                 case ALGORITHM_PARITY_0:
2036                         pd_idx = 0;
2037                         (*dd_idx)++;
2038                         break;
2039                 case ALGORITHM_PARITY_N:
2040                         pd_idx = data_disks;
2041                         break;
2042                 default:
2043                         BUG();
2044                 }
2045                 break;
2046         case 6:
2047
2048                 switch (algorithm) {
2049                 case ALGORITHM_LEFT_ASYMMETRIC:
2050                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2051                         qd_idx = pd_idx + 1;
2052                         if (pd_idx == raid_disks-1) {
2053                                 (*dd_idx)++;    /* Q D D D P */
2054                                 qd_idx = 0;
2055                         } else if (*dd_idx >= pd_idx)
2056                                 (*dd_idx) += 2; /* D D P Q D */
2057                         break;
2058                 case ALGORITHM_RIGHT_ASYMMETRIC:
2059                         pd_idx = sector_div(stripe2, raid_disks);
2060                         qd_idx = pd_idx + 1;
2061                         if (pd_idx == raid_disks-1) {
2062                                 (*dd_idx)++;    /* Q D D D P */
2063                                 qd_idx = 0;
2064                         } else if (*dd_idx >= pd_idx)
2065                                 (*dd_idx) += 2; /* D D P Q D */
2066                         break;
2067                 case ALGORITHM_LEFT_SYMMETRIC:
2068                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2069                         qd_idx = (pd_idx + 1) % raid_disks;
2070                         *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2071                         break;
2072                 case ALGORITHM_RIGHT_SYMMETRIC:
2073                         pd_idx = sector_div(stripe2, raid_disks);
2074                         qd_idx = (pd_idx + 1) % raid_disks;
2075                         *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2076                         break;
2077
2078                 case ALGORITHM_PARITY_0:
2079                         pd_idx = 0;
2080                         qd_idx = 1;
2081                         (*dd_idx) += 2;
2082                         break;
2083                 case ALGORITHM_PARITY_N:
2084                         pd_idx = data_disks;
2085                         qd_idx = data_disks + 1;
2086                         break;
2087
2088                 case ALGORITHM_ROTATING_ZERO_RESTART:
2089                         /* Exactly the same as RIGHT_ASYMMETRIC, but or
2090                          * of blocks for computing Q is different.
2091                          */
2092                         pd_idx = sector_div(stripe2, raid_disks);
2093                         qd_idx = pd_idx + 1;
2094                         if (pd_idx == raid_disks-1) {
2095                                 (*dd_idx)++;    /* Q D D D P */
2096                                 qd_idx = 0;
2097                         } else if (*dd_idx >= pd_idx)
2098                                 (*dd_idx) += 2; /* D D P Q D */
2099                         ddf_layout = 1;
2100                         break;
2101
2102                 case ALGORITHM_ROTATING_N_RESTART:
2103                         /* Same a left_asymmetric, by first stripe is
2104                          * D D D P Q  rather than
2105                          * Q D D D P
2106                          */
2107                         stripe2 += 1;
2108                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2109                         qd_idx = pd_idx + 1;
2110                         if (pd_idx == raid_disks-1) {
2111                                 (*dd_idx)++;    /* Q D D D P */
2112                                 qd_idx = 0;
2113                         } else if (*dd_idx >= pd_idx)
2114                                 (*dd_idx) += 2; /* D D P Q D */
2115                         ddf_layout = 1;
2116                         break;
2117
2118                 case ALGORITHM_ROTATING_N_CONTINUE:
2119                         /* Same as left_symmetric but Q is before P */
2120                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2121                         qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
2122                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2123                         ddf_layout = 1;
2124                         break;
2125
2126                 case ALGORITHM_LEFT_ASYMMETRIC_6:
2127                         /* RAID5 left_asymmetric, with Q on last device */
2128                         pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2129                         if (*dd_idx >= pd_idx)
2130                                 (*dd_idx)++;
2131                         qd_idx = raid_disks - 1;
2132                         break;
2133
2134                 case ALGORITHM_RIGHT_ASYMMETRIC_6:
2135                         pd_idx = sector_div(stripe2, raid_disks-1);
2136                         if (*dd_idx >= pd_idx)
2137                                 (*dd_idx)++;
2138                         qd_idx = raid_disks - 1;
2139                         break;
2140
2141                 case ALGORITHM_LEFT_SYMMETRIC_6:
2142                         pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2143                         *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2144                         qd_idx = raid_disks - 1;
2145                         break;
2146
2147                 case ALGORITHM_RIGHT_SYMMETRIC_6:
2148                         pd_idx = sector_div(stripe2, raid_disks-1);
2149                         *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2150                         qd_idx = raid_disks - 1;
2151                         break;
2152
2153                 case ALGORITHM_PARITY_0_6:
2154                         pd_idx = 0;
2155                         (*dd_idx)++;
2156                         qd_idx = raid_disks - 1;
2157                         break;
2158
2159                 default:
2160                         BUG();
2161                 }
2162                 break;
2163         }
2164
2165         if (sh) {
2166                 sh->pd_idx = pd_idx;
2167                 sh->qd_idx = qd_idx;
2168                 sh->ddf_layout = ddf_layout;
2169         }
2170         /*
2171          * Finally, compute the new sector number
2172          */
2173         new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
2174         return new_sector;
2175 }
2176
2177
2178 static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous)
2179 {
2180         struct r5conf *conf = sh->raid_conf;
2181         int raid_disks = sh->disks;
2182         int data_disks = raid_disks - conf->max_degraded;
2183         sector_t new_sector = sh->sector, check;
2184         int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2185                                          : conf->chunk_sectors;
2186         int algorithm = previous ? conf->prev_algo
2187                                  : conf->algorithm;
2188         sector_t stripe;
2189         int chunk_offset;
2190         sector_t chunk_number;
2191         int dummy1, dd_idx = i;
2192         sector_t r_sector;
2193         struct stripe_head sh2;
2194
2195
2196         chunk_offset = sector_div(new_sector, sectors_per_chunk);
2197         stripe = new_sector;
2198
2199         if (i == sh->pd_idx)
2200                 return 0;
2201         switch(conf->level) {
2202         case 4: break;
2203         case 5:
2204                 switch (algorithm) {
2205                 case ALGORITHM_LEFT_ASYMMETRIC:
2206                 case ALGORITHM_RIGHT_ASYMMETRIC:
2207                         if (i > sh->pd_idx)
2208                                 i--;
2209                         break;
2210                 case ALGORITHM_LEFT_SYMMETRIC:
2211                 case ALGORITHM_RIGHT_SYMMETRIC:
2212                         if (i < sh->pd_idx)
2213                                 i += raid_disks;
2214                         i -= (sh->pd_idx + 1);
2215                         break;
2216                 case ALGORITHM_PARITY_0:
2217                         i -= 1;
2218                         break;
2219                 case ALGORITHM_PARITY_N:
2220                         break;
2221                 default:
2222                         BUG();
2223                 }
2224                 break;
2225         case 6:
2226                 if (i == sh->qd_idx)
2227                         return 0; /* It is the Q disk */
2228                 switch (algorithm) {
2229                 case ALGORITHM_LEFT_ASYMMETRIC:
2230                 case ALGORITHM_RIGHT_ASYMMETRIC:
2231                 case ALGORITHM_ROTATING_ZERO_RESTART:
2232                 case ALGORITHM_ROTATING_N_RESTART:
2233                         if (sh->pd_idx == raid_disks-1)
2234                                 i--;    /* Q D D D P */
2235                         else if (i > sh->pd_idx)
2236                                 i -= 2; /* D D P Q D */
2237                         break;
2238                 case ALGORITHM_LEFT_SYMMETRIC:
2239                 case ALGORITHM_RIGHT_SYMMETRIC:
2240                         if (sh->pd_idx == raid_disks-1)
2241                                 i--; /* Q D D D P */
2242                         else {
2243                                 /* D D P Q D */
2244                                 if (i < sh->pd_idx)
2245                                         i += raid_disks;
2246                                 i -= (sh->pd_idx + 2);
2247                         }
2248                         break;
2249                 case ALGORITHM_PARITY_0:
2250                         i -= 2;
2251                         break;
2252                 case ALGORITHM_PARITY_N:
2253                         break;
2254                 case ALGORITHM_ROTATING_N_CONTINUE:
2255                         /* Like left_symmetric, but P is before Q */
2256                         if (sh->pd_idx == 0)
2257                                 i--;    /* P D D D Q */
2258                         else {
2259                                 /* D D Q P D */
2260                                 if (i < sh->pd_idx)
2261                                         i += raid_disks;
2262                                 i -= (sh->pd_idx + 1);
2263                         }
2264                         break;
2265                 case ALGORITHM_LEFT_ASYMMETRIC_6:
2266                 case ALGORITHM_RIGHT_ASYMMETRIC_6:
2267                         if (i > sh->pd_idx)
2268                                 i--;
2269                         break;
2270                 case ALGORITHM_LEFT_SYMMETRIC_6:
2271                 case ALGORITHM_RIGHT_SYMMETRIC_6:
2272                         if (i < sh->pd_idx)
2273                                 i += data_disks + 1;
2274                         i -= (sh->pd_idx + 1);
2275                         break;
2276                 case ALGORITHM_PARITY_0_6:
2277                         i -= 1;
2278                         break;
2279                 default:
2280                         BUG();
2281                 }
2282                 break;
2283         }
2284
2285         chunk_number = stripe * data_disks + i;
2286         r_sector = chunk_number * sectors_per_chunk + chunk_offset;
2287
2288         check = raid5_compute_sector(conf, r_sector,
2289                                      previous, &dummy1, &sh2);
2290         if (check != sh->sector || dummy1 != dd_idx || sh2.pd_idx != sh->pd_idx
2291                 || sh2.qd_idx != sh->qd_idx) {
2292                 printk(KERN_ERR "md/raid:%s: compute_blocknr: map not correct\n",
2293                        mdname(conf->mddev));
2294                 return 0;
2295         }
2296         return r_sector;
2297 }
2298
2299
2300 static void
2301 schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
2302                          int rcw, int expand)
2303 {
2304         int i, pd_idx = sh->pd_idx, disks = sh->disks;
2305         struct r5conf *conf = sh->raid_conf;
2306         int level = conf->level;
2307
2308         if (rcw) {
2309
2310                 for (i = disks; i--; ) {
2311                         struct r5dev *dev = &sh->dev[i];
2312
2313                         if (dev->towrite) {
2314                                 set_bit(R5_LOCKED, &dev->flags);
2315                                 set_bit(R5_Wantdrain, &dev->flags);
2316                                 if (!expand)
2317                                         clear_bit(R5_UPTODATE, &dev->flags);
2318                                 s->locked++;
2319                         }
2320                 }
2321                 /* if we are not expanding this is a proper write request, and
2322                  * there will be bios with new data to be drained into the
2323                  * stripe cache
2324                  */
2325                 if (!expand) {
2326                         if (!s->locked)
2327                                 /* False alarm, nothing to do */
2328                                 return;
2329                         sh->reconstruct_state = reconstruct_state_drain_run;
2330                         set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2331                 } else
2332                         sh->reconstruct_state = reconstruct_state_run;
2333
2334                 set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2335
2336                 if (s->locked + conf->max_degraded == disks)
2337                         if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
2338                                 atomic_inc(&conf->pending_full_writes);
2339         } else {
2340                 BUG_ON(level == 6);
2341                 BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
2342                         test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
2343
2344                 for (i = disks; i--; ) {
2345                         struct r5dev *dev = &sh->dev[i];
2346                         if (i == pd_idx)
2347                                 continue;
2348
2349                         if (dev->towrite &&
2350                             (test_bit(R5_UPTODATE, &dev->flags) ||
2351                              test_bit(R5_Wantcompute, &dev->flags))) {
2352                                 set_bit(R5_Wantdrain, &dev->flags);
2353                                 set_bit(R5_LOCKED, &dev->flags);
2354                                 clear_bit(R5_UPTODATE, &dev->flags);
2355                                 s->locked++;
2356                         }
2357                 }
2358                 if (!s->locked)
2359                         /* False alarm - nothing to do */
2360                         return;
2361                 sh->reconstruct_state = reconstruct_state_prexor_drain_run;
2362                 set_bit(STRIPE_OP_PREXOR, &s->ops_request);
2363                 set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2364                 set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2365         }
2366
2367         /* keep the parity disk(s) locked while asynchronous operations
2368          * are in flight
2369          */
2370         set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
2371         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
2372         s->locked++;
2373
2374         if (level == 6) {
2375                 int qd_idx = sh->qd_idx;
2376                 struct r5dev *dev = &sh->dev[qd_idx];
2377
2378                 set_bit(R5_LOCKED, &dev->flags);
2379                 clear_bit(R5_UPTODATE, &dev->flags);
2380                 s->locked++;
2381         }
2382
2383         pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
2384                 __func__, (unsigned long long)sh->sector,
2385                 s->locked, s->ops_request);
2386 }
2387
2388 /*
2389  * Each stripe/dev can have one or more bion attached.
2390  * toread/towrite point to the first in a chain.
2391  * The bi_next chain must be in order.
2392  */
2393 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
2394 {
2395         struct bio **bip;
2396         struct r5conf *conf = sh->raid_conf;
2397         int firstwrite=0;
2398
2399         pr_debug("adding bi b#%llu to stripe s#%llu\n",
2400                 (unsigned long long)bi->bi_sector,
2401                 (unsigned long long)sh->sector);
2402
2403         /*
2404          * If several bio share a stripe. The bio bi_phys_segments acts as a
2405          * reference count to avoid race. The reference count should already be
2406          * increased before this function is called (for example, in
2407          * make_request()), so other bio sharing this stripe will not free the
2408          * stripe. If a stripe is owned by one stripe, the stripe lock will
2409          * protect it.
2410          */
2411         spin_lock_irq(&sh->stripe_lock);
2412         if (forwrite) {
2413                 bip = &sh->dev[dd_idx].towrite;
2414                 if (*bip == NULL)
2415                         firstwrite = 1;
2416         } else
2417                 bip = &sh->dev[dd_idx].toread;
2418         while (*bip && (*bip)->bi_sector < bi->bi_sector) {
2419                 if (bio_end_sector(*bip) > bi->bi_sector)
2420                         goto overlap;
2421                 bip = & (*bip)->bi_next;
2422         }
2423         if (*bip && (*bip)->bi_sector < bio_end_sector(bi))
2424                 goto overlap;
2425
2426         BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
2427         if (*bip)
2428                 bi->bi_next = *bip;
2429         *bip = bi;
2430         raid5_inc_bi_active_stripes(bi);
2431
2432         if (forwrite) {
2433                 /* check if page is covered */
2434                 sector_t sector = sh->dev[dd_idx].sector;
2435                 for (bi=sh->dev[dd_idx].towrite;
2436                      sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
2437                              bi && bi->bi_sector <= sector;
2438                      bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
2439                         if (bio_end_sector(bi) >= sector)
2440                                 sector = bio_end_sector(bi);
2441                 }
2442                 if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
2443                         set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
2444         }
2445
2446         pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
2447                 (unsigned long long)(*bip)->bi_sector,
2448                 (unsigned long long)sh->sector, dd_idx);
2449         spin_unlock_irq(&sh->stripe_lock);
2450
2451         if (conf->mddev->bitmap && firstwrite) {
2452                 bitmap_startwrite(conf->mddev->bitmap, sh->sector,
2453                                   STRIPE_SECTORS, 0);
2454                 sh->bm_seq = conf->seq_flush+1;
2455                 set_bit(STRIPE_BIT_DELAY, &sh->state);
2456         }
2457         return 1;
2458
2459  overlap:
2460         set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
2461         spin_unlock_irq(&sh->stripe_lock);
2462         return 0;
2463 }
2464
2465 static void end_reshape(struct r5conf *conf);
2466
2467 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
2468                             struct stripe_head *sh)
2469 {
2470         int sectors_per_chunk =
2471                 previous ? conf->prev_chunk_sectors : conf->chunk_sectors;
2472         int dd_idx;
2473         int chunk_offset = sector_div(stripe, sectors_per_chunk);
2474         int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
2475
2476         raid5_compute_sector(conf,
2477                              stripe * (disks - conf->max_degraded)
2478                              *sectors_per_chunk + chunk_offset,
2479                              previous,
2480                              &dd_idx, sh);
2481 }
2482
2483 static void
2484 handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
2485                                 struct stripe_head_state *s, int disks,
2486                                 struct bio **return_bi)
2487 {
2488         int i;
2489         for (i = disks; i--; ) {
2490                 struct bio *bi;
2491                 int bitmap_end = 0;
2492
2493                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2494                         struct md_rdev *rdev;
2495                         rcu_read_lock();
2496                         rdev = rcu_dereference(conf->disks[i].rdev);
2497                         if (rdev && test_bit(In_sync, &rdev->flags))
2498                                 atomic_inc(&rdev->nr_pending);
2499                         else
2500                                 rdev = NULL;
2501                         rcu_read_unlock();
2502                         if (rdev) {
2503                                 if (!rdev_set_badblocks(
2504                                             rdev,
2505                                             sh->sector,
2506                                             STRIPE_SECTORS, 0))
2507                                         md_error(conf->mddev, rdev);
2508                                 rdev_dec_pending(rdev, conf->mddev);
2509                         }
2510                 }
2511                 spin_lock_irq(&sh->stripe_lock);
2512                 /* fail all writes first */
2513                 bi = sh->dev[i].towrite;
2514                 sh->dev[i].towrite = NULL;
2515                 spin_unlock_irq(&sh->stripe_lock);
2516                 if (bi)
2517                         bitmap_end = 1;
2518
2519                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2520                         wake_up(&conf->wait_for_overlap);
2521
2522                 while (bi && bi->bi_sector <
2523                         sh->dev[i].sector + STRIPE_SECTORS) {
2524                         struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
2525                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
2526                         if (!raid5_dec_bi_active_stripes(bi)) {
2527                                 md_write_end(conf->mddev);
2528                                 bi->bi_next = *return_bi;
2529                                 *return_bi = bi;
2530                         }
2531                         bi = nextbi;
2532                 }
2533                 if (bitmap_end)
2534                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2535                                 STRIPE_SECTORS, 0, 0);
2536                 bitmap_end = 0;
2537                 /* and fail all 'written' */
2538                 bi = sh->dev[i].written;
2539                 sh->dev[i].written = NULL;
2540                 if (bi) bitmap_end = 1;
2541                 while (bi && bi->bi_sector <
2542                        sh->dev[i].sector + STRIPE_SECTORS) {
2543                         struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
2544                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
2545                         if (!raid5_dec_bi_active_stripes(bi)) {
2546                                 md_write_end(conf->mddev);
2547                                 bi->bi_next = *return_bi;
2548                                 *return_bi = bi;
2549                         }
2550                         bi = bi2;
2551                 }
2552
2553                 /* fail any reads if this device is non-operational and
2554                  * the data has not reached the cache yet.
2555                  */
2556                 if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
2557                     (!test_bit(R5_Insync, &sh->dev[i].flags) ||
2558                       test_bit(R5_ReadError, &sh->dev[i].flags))) {
2559                         spin_lock_irq(&sh->stripe_lock);
2560                         bi = sh->dev[i].toread;
2561                         sh->dev[i].toread = NULL;
2562                         spin_unlock_irq(&sh->stripe_lock);
2563                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2564                                 wake_up(&conf->wait_for_overlap);
2565                         while (bi && bi->bi_sector <
2566                                sh->dev[i].sector + STRIPE_SECTORS) {
2567                                 struct bio *nextbi =
2568                                         r5_next_bio(bi, sh->dev[i].sector);
2569                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
2570                                 if (!raid5_dec_bi_active_stripes(bi)) {
2571                                         bi->bi_next = *return_bi;
2572                                         *return_bi = bi;
2573                                 }
2574                                 bi = nextbi;
2575                         }
2576                 }
2577                 if (bitmap_end)
2578                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2579                                         STRIPE_SECTORS, 0, 0);
2580                 /* If we were in the middle of a write the parity block might
2581                  * still be locked - so just clear all R5_LOCKED flags
2582                  */
2583                 clear_bit(R5_LOCKED, &sh->dev[i].flags);
2584         }
2585
2586         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2587                 if (atomic_dec_and_test(&conf->pending_full_writes))
2588                         md_wakeup_thread(conf->mddev->thread);
2589 }
2590
2591 static void
2592 handle_failed_sync(struct r5conf *conf, struct stripe_head *sh,
2593                    struct stripe_head_state *s)
2594 {
2595         int abort = 0;
2596         int i;
2597
2598         clear_bit(STRIPE_SYNCING, &sh->state);
2599         if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
2600                 wake_up(&conf->wait_for_overlap);
2601         s->syncing = 0;
2602         s->replacing = 0;
2603         /* There is nothing more to do for sync/check/repair.
2604          * Don't even need to abort as that is handled elsewhere
2605          * if needed, and not always wanted e.g. if there is a known
2606          * bad block here.
2607          * For recover/replace we need to record a bad block on all
2608          * non-sync devices, or abort the recovery
2609          */
2610         if (test_bit(MD_RECOVERY_RECOVER, &conf->mddev->recovery)) {
2611                 /* During recovery devices cannot be removed, so
2612                  * locking and refcounting of rdevs is not needed
2613                  */
2614                 for (i = 0; i < conf->raid_disks; i++) {
2615                         struct md_rdev *rdev = conf->disks[i].rdev;
2616                         if (rdev
2617                             && !test_bit(Faulty, &rdev->flags)
2618                             && !test_bit(In_sync, &rdev->flags)
2619                             && !rdev_set_badblocks(rdev, sh->sector,
2620                                                    STRIPE_SECTORS, 0))
2621                                 abort = 1;
2622                         rdev = conf->disks[i].replacement;
2623                         if (rdev
2624                             && !test_bit(Faulty, &rdev->flags)
2625                             && !test_bit(In_sync, &rdev->flags)
2626                             && !rdev_set_badblocks(rdev, sh->sector,
2627                                                    STRIPE_SECTORS, 0))
2628                                 abort = 1;
2629                 }
2630                 if (abort)
2631                         conf->recovery_disabled =
2632                                 conf->mddev->recovery_disabled;
2633         }
2634         md_done_sync(conf->mddev, STRIPE_SECTORS, !abort);
2635 }
2636
2637 static int want_replace(struct stripe_head *sh, int disk_idx)
2638 {
2639         struct md_rdev *rdev;
2640         int rv = 0;
2641         /* Doing recovery so rcu locking not required */
2642         rdev = sh->raid_conf->disks[disk_idx].replacement;
2643         if (rdev
2644             && !test_bit(Faulty, &rdev->flags)
2645             && !test_bit(In_sync, &rdev->flags)
2646             && (rdev->recovery_offset <= sh->sector
2647                 || rdev->mddev->recovery_cp <= sh->sector))
2648                 rv = 1;
2649
2650         return rv;
2651 }
2652
2653 /* fetch_block - checks the given member device to see if its data needs
2654  * to be read or computed to satisfy a request.
2655  *
2656  * Returns 1 when no more member devices need to be checked, otherwise returns
2657  * 0 to tell the loop in handle_stripe_fill to continue
2658  */
2659 static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
2660                        int disk_idx, int disks)
2661 {
2662         struct r5dev *dev = &sh->dev[disk_idx];
2663         struct r5dev *fdev[2] = { &sh->dev[s->failed_num[0]],
2664                                   &sh->dev[s->failed_num[1]] };
2665
2666         /* is the data in this block needed, and can we get it? */
2667         if (!test_bit(R5_LOCKED, &dev->flags) &&
2668             !test_bit(R5_UPTODATE, &dev->flags) &&
2669             (dev->toread ||
2670              (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
2671              s->syncing || s->expanding ||
2672              (s->replacing && want_replace(sh, disk_idx)) ||
2673              (s->failed >= 1 && fdev[0]->toread) ||
2674              (s->failed >= 2 && fdev[1]->toread) ||
2675              (sh->raid_conf->level <= 5 && s->failed && fdev[0]->towrite &&
2676               !test_bit(R5_OVERWRITE, &fdev[0]->flags)) ||
2677              (sh->raid_conf->level == 6 && s->failed && s->to_write))) {
2678                 /* we would like to get this block, possibly by computing it,
2679                  * otherwise read it if the backing disk is insync
2680                  */
2681                 BUG_ON(test_bit(R5_Wantcompute, &dev->flags));
2682                 BUG_ON(test_bit(R5_Wantread, &dev->flags));
2683                 if ((s->uptodate == disks - 1) &&
2684                     (s->failed && (disk_idx == s->failed_num[0] ||
2685                                    disk_idx == s->failed_num[1]))) {
2686                         /* have disk failed, and we're requested to fetch it;
2687                          * do compute it
2688                          */
2689                         pr_debug("Computing stripe %llu block %d\n",
2690                                (unsigned long long)sh->sector, disk_idx);
2691                         set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2692                         set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2693                         set_bit(R5_Wantcompute, &dev->flags);
2694                         sh->ops.target = disk_idx;
2695                         sh->ops.target2 = -1; /* no 2nd target */
2696                         s->req_compute = 1;
2697                         /* Careful: from this point on 'uptodate' is in the eye
2698                          * of raid_run_ops which services 'compute' operations
2699                          * before writes. R5_Wantcompute flags a block that will
2700                          * be R5_UPTODATE by the time it is needed for a
2701                          * subsequent operation.
2702                          */
2703                         s->uptodate++;
2704                         return 1;
2705                 } else if (s->uptodate == disks-2 && s->failed >= 2) {
2706                         /* Computing 2-failure is *very* expensive; only
2707                          * do it if failed >= 2
2708                          */
2709                         int other;
2710                         for (other = disks; other--; ) {
2711                                 if (other == disk_idx)
2712                                         continue;
2713                                 if (!test_bit(R5_UPTODATE,
2714                                       &sh->dev[other].flags))
2715                                         break;
2716                         }
2717                         BUG_ON(other < 0);
2718                         pr_debug("Computing stripe %llu blocks %d,%d\n",
2719                                (unsigned long long)sh->sector,
2720                                disk_idx, other);
2721                         set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2722                         set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2723                         set_bit(R5_Wantcompute, &sh->dev[disk_idx].flags);
2724                         set_bit(R5_Wantcompute, &sh->dev[other].flags);
2725                         sh->ops.target = disk_idx;
2726                         sh->ops.target2 = other;
2727                         s->uptodate += 2;
2728                         s->req_compute = 1;
2729                         return 1;
2730                 } else if (test_bit(R5_Insync, &dev->flags)) {
2731                         set_bit(R5_LOCKED, &dev->flags);
2732                         set_bit(R5_Wantread, &dev->flags);
2733                         s->locked++;
2734                         pr_debug("Reading block %d (sync=%d)\n",
2735                                 disk_idx, s->syncing);
2736                 }
2737         }
2738
2739         return 0;
2740 }
2741
2742 /**
2743  * handle_stripe_fill - read or compute data to satisfy pending requests.
2744  */
2745 static void handle_stripe_fill(struct stripe_head *sh,
2746                                struct stripe_head_state *s,
2747                                int disks)
2748 {
2749         int i;
2750
2751         /* look for blocks to read/compute, skip this if a compute
2752          * is already in flight, or if the stripe contents are in the
2753          * midst of changing due to a write
2754          */
2755         if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
2756             !sh->reconstruct_state)
2757                 for (i = disks; i--; )
2758                         if (fetch_block(sh, s, i, disks))
2759                                 break;
2760         set_bit(STRIPE_HANDLE, &sh->state);
2761 }
2762
2763
2764 /* handle_stripe_clean_event
2765  * any written block on an uptodate or failed drive can be returned.
2766  * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
2767  * never LOCKED, so we don't need to test 'failed' directly.
2768  */
2769 static void handle_stripe_clean_event(struct r5conf *conf,
2770         struct stripe_head *sh, int disks, struct bio **return_bi)
2771 {
2772         int i;
2773         struct r5dev *dev;
2774         int discard_pending = 0;
2775
2776         for (i = disks; i--; )
2777                 if (sh->dev[i].written) {
2778                         dev = &sh->dev[i];
2779                         if (!test_bit(R5_LOCKED, &dev->flags) &&
2780                             (test_bit(R5_UPTODATE, &dev->flags) ||
2781                              test_bit(R5_Discard, &dev->flags))) {
2782                                 /* We can return any write requests */
2783                                 struct bio *wbi, *wbi2;
2784                                 pr_debug("Return write for disc %d\n", i);
2785                                 if (test_and_clear_bit(R5_Discard, &dev->flags))
2786                                         clear_bit(R5_UPTODATE, &dev->flags);
2787                                 wbi = dev->written;
2788                                 dev->written = NULL;
2789                                 while (wbi && wbi->bi_sector <
2790                                         dev->sector + STRIPE_SECTORS) {
2791                                         wbi2 = r5_next_bio(wbi, dev->sector);
2792                                         if (!raid5_dec_bi_active_stripes(wbi)) {
2793                                                 md_write_end(conf->mddev);
2794                                                 wbi->bi_next = *return_bi;
2795                                                 *return_bi = wbi;
2796                                         }
2797                                         wbi = wbi2;
2798                                 }
2799                                 bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2800                                                 STRIPE_SECTORS,
2801                                          !test_bit(STRIPE_DEGRADED, &sh->state),
2802                                                 0);
2803                         } else if (test_bit(R5_Discard, &dev->flags))
2804                                 discard_pending = 1;
2805                 }
2806         if (!discard_pending &&
2807             test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
2808                 clear_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
2809                 clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
2810                 if (sh->qd_idx >= 0) {
2811                         clear_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
2812                         clear_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags);
2813                 }
2814                 /* now that discard is done we can proceed with any sync */
2815                 clear_bit(STRIPE_DISCARD, &sh->state);
2816                 /*
2817                  * SCSI discard will change some bio fields and the stripe has
2818                  * no updated data, so remove it from hash list and the stripe
2819                  * will be reinitialized
2820                  */
2821                 spin_lock_irq(&conf->device_lock);
2822                 remove_hash(sh);
2823                 spin_unlock_irq(&conf->device_lock);
2824                 if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state))
2825                         set_bit(STRIPE_HANDLE, &sh->state);
2826
2827         }
2828
2829         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2830                 if (atomic_dec_and_test(&conf->pending_full_writes))
2831                         md_wakeup_thread(conf->mddev->thread);
2832 }
2833
2834 static void handle_stripe_dirtying(struct r5conf *conf,
2835                                    struct stripe_head *sh,
2836                                    struct stripe_head_state *s,
2837                                    int disks)
2838 {
2839         int rmw = 0, rcw = 0, i;
2840         sector_t recovery_cp = conf->mddev->recovery_cp;
2841
2842         /* RAID6 requires 'rcw' in current implementation.
2843          * Otherwise, check whether resync is now happening or should start.
2844          * If yes, then the array is dirty (after unclean shutdown or
2845          * initial creation), so parity in some stripes might be inconsistent.
2846          * In this case, we need to always do reconstruct-write, to ensure
2847          * that in case of drive failure or read-error correction, we
2848          * generate correct data from the parity.
2849          */
2850         if (conf->max_degraded == 2 ||
2851             (recovery_cp < MaxSector && sh->sector >= recovery_cp)) {
2852                 /* Calculate the real rcw later - for now make it
2853                  * look like rcw is cheaper
2854                  */
2855                 rcw = 1; rmw = 2;
2856                 pr_debug("force RCW max_degraded=%u, recovery_cp=%llu sh->sector=%llu\n",
2857                          conf->max_degraded, (unsigned long long)recovery_cp,
2858                          (unsigned long long)sh->sector);
2859         } else for (i = disks; i--; ) {
2860                 /* would I have to read this buffer for read_modify_write */
2861                 struct r5dev *dev = &sh->dev[i];
2862                 if ((dev->towrite || i == sh->pd_idx) &&
2863                     !test_bit(R5_LOCKED, &dev->flags) &&
2864                     !(test_bit(R5_UPTODATE, &dev->flags) ||
2865                       test_bit(R5_Wantcompute, &dev->flags))) {
2866                         if (test_bit(R5_Insync, &dev->flags))
2867                                 rmw++;
2868                         else
2869                                 rmw += 2*disks;  /* cannot read it */
2870                 }
2871                 /* Would I have to read this buffer for reconstruct_write */
2872                 if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
2873                     !test_bit(R5_LOCKED, &dev->flags) &&
2874                     !(test_bit(R5_UPTODATE, &dev->flags) ||
2875                     test_bit(R5_Wantcompute, &dev->flags))) {
2876                         if (test_bit(R5_Insync, &dev->flags)) rcw++;
2877                         else
2878                                 rcw += 2*disks;
2879                 }
2880         }
2881         pr_debug("for sector %llu, rmw=%d rcw=%d\n",
2882                 (unsigned long long)sh->sector, rmw, rcw);
2883         set_bit(STRIPE_HANDLE, &sh->state);
2884         if (rmw < rcw && rmw > 0) {
2885                 /* prefer read-modify-write, but need to get some data */
2886                 if (conf->mddev->queue)
2887                         blk_add_trace_msg(conf->mddev->queue,
2888                                           "raid5 rmw %llu %d",
2889                                           (unsigned long long)sh->sector, rmw);
2890                 for (i = disks; i--; ) {
2891                         struct r5dev *dev = &sh->dev[i];
2892                         if ((dev->towrite || i == sh->pd_idx) &&
2893                             !test_bit(R5_LOCKED, &dev->flags) &&
2894                             !(test_bit(R5_UPTODATE, &dev->flags) ||
2895                             test_bit(R5_Wantcompute, &dev->flags)) &&
2896                             test_bit(R5_Insync, &dev->flags)) {
2897                                 if (
2898                                   test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2899                                         pr_debug("Read_old block "
2900                                                  "%d for r-m-w\n", i);
2901                                         set_bit(R5_LOCKED, &dev->flags);
2902                                         set_bit(R5_Wantread, &dev->flags);
2903                                         s->locked++;
2904                                 } else {
2905                                         set_bit(STRIPE_DELAYED, &sh->state);
2906                                         set_bit(STRIPE_HANDLE, &sh->state);
2907                                 }
2908                         }
2909                 }
2910         }
2911         if (rcw <= rmw && rcw > 0) {
2912                 /* want reconstruct write, but need to get some data */
2913                 int qread =0;
2914                 rcw = 0;
2915                 for (i = disks; i--; ) {
2916                         struct r5dev *dev = &sh->dev[i];
2917                         if (!test_bit(R5_OVERWRITE, &dev->flags) &&
2918                             i != sh->pd_idx && i != sh->qd_idx &&
2919                             !test_bit(R5_LOCKED, &dev->flags) &&
2920                             !(test_bit(R5_UPTODATE, &dev->flags) ||
2921                               test_bit(R5_Wantcompute, &dev->flags))) {
2922                                 rcw++;
2923                                 if (!test_bit(R5_Insync, &dev->flags))
2924                                         continue; /* it's a failed drive */
2925                                 if (
2926                                   test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2927                                         pr_debug("Read_old block "
2928                                                 "%d for Reconstruct\n", i);
2929                                         set_bit(R5_LOCKED, &dev->flags);
2930                                         set_bit(R5_Wantread, &dev->flags);
2931                                         s->locked++;
2932                                         qread++;
2933                                 } else {
2934                                         set_bit(STRIPE_DELAYED, &sh->state);
2935                                         set_bit(STRIPE_HANDLE, &sh->state);
2936                                 }
2937                         }
2938                 }
2939                 if (rcw && conf->mddev->queue)
2940                         blk_add_trace_msg(conf->mddev->queue, "raid5 rcw %llu %d %d %d",
2941                                           (unsigned long long)sh->sector,
2942                                           rcw, qread, test_bit(STRIPE_DELAYED, &sh->state));
2943         }
2944         /* now if nothing is locked, and if we have enough data,
2945          * we can start a write request
2946          */
2947         /* since handle_stripe can be called at any time we need to handle the
2948          * case where a compute block operation has been submitted and then a
2949          * subsequent call wants to start a write request.  raid_run_ops only
2950          * handles the case where compute block and reconstruct are requested
2951          * simultaneously.  If this is not the case then new writes need to be
2952          * held off until the compute completes.
2953          */
2954         if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
2955             (s->locked == 0 && (rcw == 0 || rmw == 0) &&
2956             !test_bit(STRIPE_BIT_DELAY, &sh->state)))
2957                 schedule_reconstruction(sh, s, rcw == 0, 0);
2958 }
2959
2960 static void handle_parity_checks5(struct r5conf *conf, struct stripe_head *sh,
2961                                 struct stripe_head_state *s, int disks)
2962 {
2963         struct r5dev *dev = NULL;
2964
2965         set_bit(STRIPE_HANDLE, &sh->state);
2966
2967         switch (sh->check_state) {
2968         case check_state_idle:
2969                 /* start a new check operation if there are no failures */
2970                 if (s->failed == 0) {
2971                         BUG_ON(s->uptodate != disks);
2972                         sh->check_state = check_state_run;
2973                         set_bit(STRIPE_OP_CHECK, &s->ops_request);
2974                         clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
2975                         s->uptodate--;
2976                         break;
2977                 }
2978                 dev = &sh->dev[s->failed_num[0]];
2979                 /* fall through */
2980         case check_state_compute_result:
2981                 sh->check_state = check_state_idle;
2982                 if (!dev)
2983                         dev = &sh->dev[sh->pd_idx];
2984
2985                 /* check that a write has not made the stripe insync */
2986                 if (test_bit(STRIPE_INSYNC, &sh->state))
2987                         break;
2988
2989                 /* either failed parity check, or recovery is happening */
2990                 BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
2991                 BUG_ON(s->uptodate != disks);
2992
2993                 set_bit(R5_LOCKED, &dev->flags);
2994                 s->locked++;
2995                 set_bit(R5_Wantwrite, &dev->flags);
2996
2997                 clear_bit(STRIPE_DEGRADED, &sh->state);
2998                 set_bit(STRIPE_INSYNC, &sh->state);
2999                 break;
3000         case check_state_run:
3001                 break; /* we will be called again upon completion */
3002         case check_state_check_result:
3003                 sh->check_state = check_state_idle;
3004
3005                 /* if a failure occurred during the check operation, leave
3006                  * STRIPE_INSYNC not set and let the stripe be handled again
3007                  */
3008                 if (s->failed)
3009                         break;
3010
3011                 /* handle a successful check operation, if parity is correct
3012                  * we are done.  Otherwise update the mismatch count and repair
3013                  * parity if !MD_RECOVERY_CHECK
3014                  */
3015                 if ((sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) == 0)
3016                         /* parity is correct (on disc,
3017                          * not in buffer any more)
3018                          */
3019                         set_bit(STRIPE_INSYNC, &sh->state);
3020                 else {
3021                         atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3022                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3023                                 /* don't try to repair!! */
3024                                 set_bit(STRIPE_INSYNC, &sh->state);
3025                         else {
3026                                 sh->check_state = check_state_compute_run;
3027                                 set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3028                                 set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3029                                 set_bit(R5_Wantcompute,
3030                                         &sh->dev[sh->pd_idx].flags);
3031                                 sh->ops.target = sh->pd_idx;
3032                                 sh->ops.target2 = -1;
3033                                 s->uptodate++;
3034                         }
3035                 }
3036                 break;
3037         case check_state_compute_run:
3038                 break;
3039         default:
3040                 printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
3041                        __func__, sh->check_state,
3042                        (unsigned long long) sh->sector);
3043                 BUG();
3044         }
3045 }
3046
3047
3048 static void handle_parity_checks6(struct r5conf *conf, struct stripe_head *sh,
3049                                   struct stripe_head_state *s,
3050                                   int disks)
3051 {
3052         int pd_idx = sh->pd_idx;
3053         int qd_idx = sh->qd_idx;
3054         struct r5dev *dev;
3055
3056         set_bit(STRIPE_HANDLE, &sh->state);
3057
3058         BUG_ON(s->failed > 2);
3059
3060         /* Want to check and possibly repair P and Q.
3061          * However there could be one 'failed' device, in which
3062          * case we can only check one of them, possibly using the
3063          * other to generate missing data
3064          */
3065
3066         switch (sh->check_state) {
3067         case check_state_idle:
3068                 /* start a new check operation if there are < 2 failures */
3069                 if (s->failed == s->q_failed) {
3070                         /* The only possible failed device holds Q, so it
3071                          * makes sense to check P (If anything else were failed,
3072                          * we would have used P to recreate it).
3073                          */
3074                         sh->check_state = check_state_run;
3075                 }
3076                 if (!s->q_failed && s->failed < 2) {
3077                         /* Q is not failed, and we didn't use it to generate
3078                          * anything, so it makes sense to check it
3079                          */
3080                         if (sh->check_state == check_state_run)
3081                                 sh->check_state = check_state_run_pq;
3082                         else
3083                                 sh->check_state = check_state_run_q;
3084                 }
3085
3086                 /* discard potentially stale zero_sum_result */
3087                 sh->ops.zero_sum_result = 0;
3088
3089                 if (sh->check_state == check_state_run) {
3090                         /* async_xor_zero_sum destroys the contents of P */
3091                         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
3092                         s->uptodate--;
3093                 }
3094                 if (sh->check_state >= check_state_run &&
3095                     sh->check_state <= check_state_run_pq) {
3096                         /* async_syndrome_zero_sum preserves P and Q, so
3097                          * no need to mark them !uptodate here
3098                          */
3099                         set_bit(STRIPE_OP_CHECK, &s->ops_request);
3100                         break;
3101                 }
3102
3103                 /* we have 2-disk failure */
3104                 BUG_ON(s->failed != 2);
3105                 /* fall through */
3106         case check_state_compute_result:
3107                 sh->check_state = check_state_idle;
3108
3109                 /* check that a write has not made the stripe insync */
3110                 if (test_bit(STRIPE_INSYNC, &sh->state))
3111                         break;
3112
3113                 /* now write out any block on a failed drive,
3114                  * or P or Q if they were recomputed
3115                  */
3116                 BUG_ON(s->uptodate < disks - 1); /* We don't need Q to recover */
3117                 if (s->failed == 2) {
3118                         dev = &sh->dev[s->failed_num[1]];
3119                         s->locked++;
3120                         set_bit(R5_LOCKED, &dev->flags);
3121                         set_bit(R5_Wantwrite, &dev->flags);
3122                 }
3123                 if (s->failed >= 1) {
3124                         dev = &sh->dev[s->failed_num[0]];
3125                         s->locked++;
3126                         set_bit(R5_LOCKED, &dev->flags);
3127                         set_bit(R5_Wantwrite, &dev->flags);
3128                 }
3129                 if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3130                         dev = &sh->dev[pd_idx];
3131                         s->locked++;
3132                         set_bit(R5_LOCKED, &dev->flags);
3133                         set_bit(R5_Wantwrite, &dev->flags);
3134                 }
3135                 if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3136                         dev = &sh->dev[qd_idx];
3137                         s->locked++;
3138                         set_bit(R5_LOCKED, &dev->flags);
3139                         set_bit(R5_Wantwrite, &dev->flags);
3140                 }
3141                 clear_bit(STRIPE_DEGRADED, &sh->state);
3142
3143                 set_bit(STRIPE_INSYNC, &sh->state);
3144                 break;
3145         case check_state_run:
3146         case check_state_run_q:
3147         case check_state_run_pq:
3148                 break; /* we will be called again upon completion */
3149         case check_state_check_result:
3150                 sh->check_state = check_state_idle;
3151
3152                 /* handle a successful check operation, if parity is correct
3153                  * we are done.  Otherwise update the mismatch count and repair
3154                  * parity if !MD_RECOVERY_CHECK
3155                  */
3156                 if (sh->ops.zero_sum_result == 0) {
3157                         /* both parities are correct */
3158                         if (!s->failed)
3159                                 set_bit(STRIPE_INSYNC, &sh->state);
3160                         else {
3161                                 /* in contrast to the raid5 case we can validate
3162                                  * parity, but still have a failure to write
3163                                  * back
3164                                  */
3165                                 sh->check_state = check_state_compute_result;
3166                                 /* Returning at this point means that we may go
3167                                  * off and bring p and/or q uptodate again so
3168                                  * we make sure to check zero_sum_result again
3169                                  * to verify if p or q need writeback
3170                                  */
3171                         }
3172                 } else {
3173                         atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3174                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3175                                 /* don't try to repair!! */
3176                                 set_bit(STRIPE_INSYNC, &sh->state);
3177                         else {
3178                                 int *target = &sh->ops.target;
3179
3180                                 sh->ops.target = -1;
3181                                 sh->ops.target2 = -1;
3182                                 sh->check_state = check_state_compute_run;
3183                                 set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3184                                 set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3185                                 if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3186                                         set_bit(R5_Wantcompute,
3187                                                 &sh->dev[pd_idx].flags);
3188                                         *target = pd_idx;
3189                                         target = &sh->ops.target2;
3190                                         s->uptodate++;
3191                                 }
3192                                 if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3193                                         set_bit(R5_Wantcompute,
3194                                                 &sh->dev[qd_idx].flags);
3195                                         *target = qd_idx;
3196                                         s->uptodate++;
3197                                 }
3198                         }
3199                 }
3200                 break;
3201         case check_state_compute_run:
3202                 break;
3203         default:
3204                 printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
3205                        __func__, sh->check_state,
3206                        (unsigned long long) sh->sector);
3207                 BUG();
3208         }
3209 }
3210
3211 static void handle_stripe_expansion(struct r5conf *conf, struct stripe_head *sh)
3212 {
3213         int i;
3214
3215         /* We have read all the blocks in this stripe and now we need to
3216          * copy some of them into a target stripe for expand.
3217          */
3218         struct dma_async_tx_descriptor *tx = NULL;
3219         clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3220         for (i = 0; i < sh->disks; i++)
3221                 if (i != sh->pd_idx && i != sh->qd_idx) {
3222                         int dd_idx, j;
3223                         struct stripe_head *sh2;
3224                         struct async_submit_ctl submit;
3225
3226                         sector_t bn = compute_blocknr(sh, i, 1);
3227                         sector_t s = raid5_compute_sector(conf, bn, 0,
3228                                                           &dd_idx, NULL);
3229                         sh2 = get_active_stripe(conf, s, 0, 1, 1);
3230                         if (sh2 == NULL)
3231                                 /* so far only the early blocks of this stripe
3232                                  * have been requested.  When later blocks
3233                                  * get requested, we will try again
3234                                  */
3235                                 continue;
3236                         if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
3237                            test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
3238                                 /* must have already done this block */
3239                                 release_stripe(sh2);
3240                                 continue;
3241                         }
3242
3243                         /* place all the copies on one channel */
3244                         init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
3245                         tx = async_memcpy(sh2->dev[dd_idx].page,
3246                                           sh->dev[i].page, 0, 0, STRIPE_SIZE,
3247                                           &submit);
3248
3249                         set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
3250                         set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
3251                         for (j = 0; j < conf->raid_disks; j++)
3252                                 if (j != sh2->pd_idx &&
3253                                     j != sh2->qd_idx &&
3254                                     !test_bit(R5_Expanded, &sh2->dev[j].flags))
3255                                         break;
3256                         if (j == conf->raid_disks) {
3257                                 set_bit(STRIPE_EXPAND_READY, &sh2->state);
3258                                 set_bit(STRIPE_HANDLE, &sh2->state);
3259                         }
3260                         release_stripe(sh2);
3261
3262                 }
3263         /* done submitting copies, wait for them to complete */
3264         async_tx_quiesce(&tx);
3265 }
3266
3267 /*
3268  * handle_stripe - do things to a stripe.
3269  *
3270  * We lock the stripe by setting STRIPE_ACTIVE and then examine the
3271  * state of various bits to see what needs to be done.
3272  * Possible results:
3273  *    return some read requests which now have data
3274  *    return some write requests which are safely on storage
3275  *    schedule a read on some buffers
3276  *    schedule a write of some buffers
3277  *    return confirmation of parity correctness
3278  *
3279  */
3280
3281 static void analyse_stripe(struct stripe_head *sh, struct stripe_head_state *s)
3282 {
3283         struct r5conf *conf = sh->raid_conf;
3284         int disks = sh->disks;
3285         struct r5dev *dev;
3286         int i;
3287         int do_recovery = 0;
3288
3289         memset(s, 0, sizeof(*s));
3290
3291         s->expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3292         s->expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
3293         s->failed_num[0] = -1;
3294         s->failed_num[1] = -1;
3295
3296         /* Now to look around and see what can be done */
3297         rcu_read_lock();
3298         for (i=disks; i--; ) {
3299                 struct md_rdev *rdev;
3300                 sector_t first_bad;
3301                 int bad_sectors;
3302                 int is_bad = 0;
3303
3304                 dev = &sh->dev[i];
3305
3306                 pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
3307                          i, dev->flags,
3308                          dev->toread, dev->towrite, dev->written);
3309                 /* maybe we can reply to a read
3310                  *
3311                  * new wantfill requests are only permitted while
3312                  * ops_complete_biofill is guaranteed to be inactive
3313                  */
3314                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
3315                     !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
3316                         set_bit(R5_Wantfill, &dev->flags);
3317
3318                 /* now count some things */
3319                 if (test_bit(R5_LOCKED, &dev->flags))
3320                         s->locked++;
3321                 if (test_bit(R5_UPTODATE, &dev->flags))
3322                         s->uptodate++;
3323                 if (test_bit(R5_Wantcompute, &dev->flags)) {
3324                         s->compute++;
3325                         BUG_ON(s->compute > 2);
3326                 }
3327
3328                 if (test_bit(R5_Wantfill, &dev->flags))
3329                         s->to_fill++;
3330                 else if (dev->toread)
3331                         s->to_read++;
3332                 if (dev->towrite) {
3333                         s->to_write++;
3334                         if (!test_bit(R5_OVERWRITE, &dev->flags))
3335                                 s->non_overwrite++;
3336                 }
3337                 if (dev->written)
3338                         s->written++;
3339                 /* Prefer to use the replacement for reads, but only
3340                  * if it is recovered enough and has no bad blocks.
3341                  */
3342                 rdev = rcu_dereference(conf->disks[i].replacement);
3343                 if (rdev && !test_bit(Faulty, &rdev->flags) &&
3344                     rdev->recovery_offset >= sh->sector + STRIPE_SECTORS &&
3345                     !is_badblock(rdev, sh->sector, STRIPE_SECTORS,
3346                                  &first_bad, &bad_sectors))
3347                         set_bit(R5_ReadRepl, &dev->flags);
3348                 else {
3349                         if (rdev)
3350                                 set_bit(R5_NeedReplace, &dev->flags);
3351                         rdev = rcu_dereference(conf->disks[i].rdev);
3352                         clear_bit(R5_ReadRepl, &dev->flags);
3353                 }
3354                 if (rdev && test_bit(Faulty, &rdev->flags))
3355                         rdev = NULL;
3356                 if (rdev) {
3357                         is_bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
3358                                              &first_bad, &bad_sectors);
3359                         if (s->blocked_rdev == NULL
3360                             && (test_bit(Blocked, &rdev->flags)
3361                                 || is_bad < 0)) {
3362                                 if (is_bad < 0)
3363                                         set_bit(BlockedBadBlocks,
3364                                                 &rdev->flags);
3365                                 s->blocked_rdev = rdev;
3366                                 atomic_inc(&rdev->nr_pending);
3367                         }
3368                 }
3369                 clear_bit(R5_Insync, &dev->flags);
3370                 if (!rdev)
3371                         /* Not in-sync */;
3372                 else if (is_bad) {
3373                         /* also not in-sync */
3374                         if (!test_bit(WriteErrorSeen, &rdev->flags) &&
3375                             test_bit(R5_UPTODATE, &dev->flags)) {
3376                                 /* treat as in-sync, but with a read error
3377                                  * which we can now try to correct
3378                                  */
3379                                 set_bit(R5_Insync, &dev->flags);
3380                                 set_bit(R5_ReadError, &dev->flags);
3381                         }
3382                 } else if (test_bit(In_sync, &rdev->flags))
3383                         set_bit(R5_Insync, &dev->flags);
3384                 else if (sh->sector + STRIPE_SECTORS <= rdev->recovery_offset)
3385                         /* in sync if before recovery_offset */
3386                         set_bit(R5_Insync, &dev->flags);
3387                 else if (test_bit(R5_UPTODATE, &dev->flags) &&
3388                          test_bit(R5_Expanded, &dev->flags))
3389                         /* If we've reshaped into here, we assume it is Insync.
3390                          * We will shortly update recovery_offset to make
3391                          * it official.
3392                          */
3393                         set_bit(R5_Insync, &dev->flags);
3394
3395                 if (test_bit(R5_WriteError, &dev->flags)) {
3396                         /* This flag does not apply to '.replacement'
3397                          * only to .rdev, so make sure to check that*/
3398                         struct md_rdev *rdev2 = rcu_dereference(
3399                                 conf->disks[i].rdev);
3400                         if (rdev2 == rdev)
3401                                 clear_bit(R5_Insync, &dev->flags);
3402                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3403                                 s->handle_bad_blocks = 1;
3404                                 atomic_inc(&rdev2->nr_pending);
3405                         } else
3406                                 clear_bit(R5_WriteError, &dev->flags);
3407                 }
3408                 if (test_bit(R5_MadeGood, &dev->flags)) {
3409                         /* This flag does not apply to '.replacement'
3410                          * only to .rdev, so make sure to check that*/
3411                         struct md_rdev *rdev2 = rcu_dereference(
3412                                 conf->disks[i].rdev);
3413                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3414                                 s->handle_bad_blocks = 1;
3415                                 atomic_inc(&rdev2->nr_pending);
3416                         } else
3417                                 clear_bit(R5_MadeGood, &dev->flags);
3418                 }
3419                 if (test_bit(R5_MadeGoodRepl, &dev->flags)) {
3420                         struct md_rdev *rdev2 = rcu_dereference(
3421                                 conf->disks[i].replacement);
3422                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3423                                 s->handle_bad_blocks = 1;
3424                                 atomic_inc(&rdev2->nr_pending);
3425                         } else
3426                                 clear_bit(R5_MadeGoodRepl, &dev->flags);
3427                 }
3428                 if (!test_bit(R5_Insync, &dev->flags)) {
3429                         /* The ReadError flag will just be confusing now */
3430                         clear_bit(R5_ReadError, &dev->flags);
3431                         clear_bit(R5_ReWrite, &dev->flags);
3432                 }
3433                 if (test_bit(R5_ReadError, &dev->flags))
3434                         clear_bit(R5_Insync, &dev->flags);
3435                 if (!test_bit(R5_Insync, &dev->flags)) {
3436                         if (s->failed < 2)
3437                                 s->failed_num[s->failed] = i;
3438                         s->failed++;
3439                         if (rdev && !test_bit(Faulty, &rdev->flags))
3440                                 do_recovery = 1;
3441                 }
3442         }
3443         if (test_bit(STRIPE_SYNCING, &sh->state)) {
3444                 /* If there is a failed device being replaced,
3445                  *     we must be recovering.
3446                  * else if we are after recovery_cp, we must be syncing
3447                  * else if MD_RECOVERY_REQUESTED is set, we also are syncing.
3448                  * else we can only be replacing
3449                  * sync and recovery both need to read all devices, and so
3450                  * use the same flag.
3451                  */
3452                 if (do_recovery ||
3453                     sh->sector >= conf->mddev->recovery_cp ||
3454                     test_bit(MD_RECOVERY_REQUESTED, &(conf->mddev->recovery)))
3455                         s->syncing = 1;
3456                 else
3457                         s->replacing = 1;
3458         }
3459         rcu_read_unlock();
3460 }
3461
3462 static void handle_stripe(struct stripe_head *sh)
3463 {
3464         struct stripe_head_state s;
3465         struct r5conf *conf = sh->raid_conf;
3466         int i;
3467         int prexor;
3468         int disks = sh->disks;
3469         struct r5dev *pdev, *qdev;
3470
3471         clear_bit(STRIPE_HANDLE, &sh->state);
3472         if (test_and_set_bit_lock(STRIPE_ACTIVE, &sh->state)) {
3473                 /* already being handled, ensure it gets handled
3474                  * again when current action finishes */
3475                 set_bit(STRIPE_HANDLE, &sh->state);
3476                 return;
3477         }
3478
3479         if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
3480                 spin_lock(&sh->stripe_lock);
3481                 /* Cannot process 'sync' concurrently with 'discard' */
3482                 if (!test_bit(STRIPE_DISCARD, &sh->state) &&
3483                     test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
3484                         set_bit(STRIPE_SYNCING, &sh->state);
3485                         clear_bit(STRIPE_INSYNC, &sh->state);
3486                         clear_bit(STRIPE_REPLACED, &sh->state);
3487                 }
3488                 spin_unlock(&sh->stripe_lock);
3489         }
3490         clear_bit(STRIPE_DELAYED, &sh->state);
3491
3492         pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
3493                 "pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
3494                (unsigned long long)sh->sector, sh->state,
3495                atomic_read(&sh->count), sh->pd_idx, sh->qd_idx,
3496                sh->check_state, sh->reconstruct_state);
3497
3498         analyse_stripe(sh, &s);
3499
3500         if (s.handle_bad_blocks) {
3501                 set_bit(STRIPE_HANDLE, &sh->state);
3502                 goto finish;
3503         }
3504
3505         if (unlikely(s.blocked_rdev)) {
3506                 if (s.syncing || s.expanding || s.expanded ||
3507                     s.replacing || s.to_write || s.written) {
3508                         set_bit(STRIPE_HANDLE, &sh->state);
3509                         goto finish;
3510                 }
3511                 /* There is nothing for the blocked_rdev to block */
3512                 rdev_dec_pending(s.blocked_rdev, conf->mddev);
3513                 s.blocked_rdev = NULL;
3514         }
3515
3516         if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
3517                 set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
3518                 set_bit(STRIPE_BIOFILL_RUN, &sh->state);
3519         }
3520
3521         pr_debug("locked=%d uptodate=%d to_read=%d"
3522                " to_write=%d failed=%d failed_num=%d,%d\n",
3523                s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
3524                s.failed_num[0], s.failed_num[1]);
3525         /* check if the array has lost more than max_degraded devices and,
3526          * if so, some requests might need to be failed.
3527          */
3528         if (s.failed > conf->max_degraded) {
3529                 sh->check_state = 0;
3530                 sh->reconstruct_state = 0;
3531                 if (s.to_read+s.to_write+s.written)
3532                         handle_failed_stripe(conf, sh, &s, disks, &s.return_bi);
3533                 if (s.syncing + s.replacing)
3534                         handle_failed_sync(conf, sh, &s);
3535         }
3536
3537         /* Now we check to see if any write operations have recently
3538          * completed
3539          */
3540         prexor = 0;
3541         if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
3542                 prexor = 1;
3543         if (sh->reconstruct_state == reconstruct_state_drain_result ||
3544             sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
3545                 sh->reconstruct_state = reconstruct_state_idle;
3546
3547                 /* All the 'written' buffers and the parity block are ready to
3548                  * be written back to disk
3549                  */
3550                 BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags) &&
3551                        !test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags));
3552                 BUG_ON(sh->qd_idx >= 0 &&
3553                        !test_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags) &&
3554                        !test_bit(R5_Discard, &sh->dev[sh->qd_idx].flags));
3555                 for (i = disks; i--; ) {
3556                         struct r5dev *dev = &sh->dev[i];
3557                         if (test_bit(R5_LOCKED, &dev->flags) &&
3558                                 (i == sh->pd_idx || i == sh->qd_idx ||
3559                                  dev->written)) {
3560                                 pr_debug("Writing block %d\n", i);
3561                                 set_bit(R5_Wantwrite, &dev->flags);
3562                                 if (prexor)
3563                                         continue;
3564                                 if (!test_bit(R5_Insync, &dev->flags) ||
3565                                     ((i == sh->pd_idx || i == sh->qd_idx)  &&
3566                                      s.failed == 0))
3567                                         set_bit(STRIPE_INSYNC, &sh->state);
3568                         }
3569                 }
3570                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3571                         s.dec_preread_active = 1;
3572         }
3573
3574         /*
3575          * might be able to return some write requests if the parity blocks
3576          * are safe, or on a failed drive
3577          */
3578         pdev = &sh->dev[sh->pd_idx];
3579         s.p_failed = (s.failed >= 1 && s.failed_num[0] == sh->pd_idx)
3580                 || (s.failed >= 2 && s.failed_num[1] == sh->pd_idx);
3581         qdev = &sh->dev[sh->qd_idx];
3582         s.q_failed = (s.failed >= 1 && s.failed_num[0] == sh->qd_idx)
3583                 || (s.failed >= 2 && s.failed_num[1] == sh->qd_idx)
3584                 || conf->level < 6;
3585
3586         if (s.written &&
3587             (s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
3588                              && !test_bit(R5_LOCKED, &pdev->flags)
3589                              && (test_bit(R5_UPTODATE, &pdev->flags) ||
3590                                  test_bit(R5_Discard, &pdev->flags))))) &&
3591             (s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
3592                              && !test_bit(R5_LOCKED, &qdev->flags)
3593                              && (test_bit(R5_UPTODATE, &qdev->flags) ||
3594                                  test_bit(R5_Discard, &qdev->flags))))))
3595                 handle_stripe_clean_event(conf, sh, disks, &s.return_bi);
3596
3597         /* Now we might consider reading some blocks, either to check/generate
3598          * parity, or to satisfy requests
3599          * or to load a block that is being partially written.
3600          */
3601         if (s.to_read || s.non_overwrite
3602             || (conf->level == 6 && s.to_write && s.failed)
3603             || (s.syncing && (s.uptodate + s.compute < disks))
3604             || s.replacing
3605             || s.expanding)
3606                 handle_stripe_fill(sh, &s, disks);
3607
3608         /* Now to consider new write requests and what else, if anything
3609          * should be read.  We do not handle new writes when:
3610          * 1/ A 'write' operation (copy+xor) is already in flight.
3611          * 2/ A 'check' operation is in flight, as it may clobber the parity
3612          *    block.
3613          */
3614         if (s.to_write && !sh->reconstruct_state && !sh->check_state)
3615                 handle_stripe_dirtying(conf, sh, &s, disks);
3616
3617         /* maybe we need to check and possibly fix the parity for this stripe
3618          * Any reads will already have been scheduled, so we just see if enough
3619          * data is available.  The parity check is held off while parity
3620          * dependent operations are in flight.
3621          */
3622         if (sh->check_state ||
3623             (s.syncing && s.locked == 0 &&
3624              !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
3625              !test_bit(STRIPE_INSYNC, &sh->state))) {
3626                 if (conf->level == 6)
3627                         handle_parity_checks6(conf, sh, &s, disks);
3628                 else
3629                         handle_parity_checks5(conf, sh, &s, disks);
3630         }
3631
3632         if ((s.replacing || s.syncing) && s.locked == 0
3633             && !test_bit(STRIPE_COMPUTE_RUN, &sh->state)
3634             && !test_bit(STRIPE_REPLACED, &sh->state)) {
3635                 /* Write out to replacement devices where possible */
3636                 for (i = 0; i < conf->raid_disks; i++)
3637                         if (test_bit(R5_NeedReplace, &sh->dev[i].flags)) {
3638                                 WARN_ON(!test_bit(R5_UPTODATE, &sh->dev[i].flags));
3639                                 set_bit(R5_WantReplace, &sh->dev[i].flags);
3640                                 set_bit(R5_LOCKED, &sh->dev[i].flags);
3641                                 s.locked++;
3642                         }
3643                 if (s.replacing)
3644                         set_bit(STRIPE_INSYNC, &sh->state);
3645                 set_bit(STRIPE_REPLACED, &sh->state);
3646         }
3647         if ((s.syncing || s.replacing) && s.locked == 0 &&
3648             !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
3649             test_bit(STRIPE_INSYNC, &sh->state)) {
3650                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3651                 clear_bit(STRIPE_SYNCING, &sh->state);
3652                 if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
3653                         wake_up(&conf->wait_for_overlap);
3654         }
3655
3656         /* If the failed drives are just a ReadError, then we might need
3657          * to progress the repair/check process
3658          */
3659         if (s.failed <= conf->max_degraded && !conf->mddev->ro)
3660                 for (i = 0; i < s.failed; i++) {
3661                         struct r5dev *dev = &sh->dev[s.failed_num[i]];
3662                         if (test_bit(R5_ReadError, &dev->flags)
3663                             && !test_bit(R5_LOCKED, &dev->flags)
3664                             && test_bit(R5_UPTODATE, &dev->flags)
3665                                 ) {
3666                                 if (!test_bit(R5_ReWrite, &dev->flags)) {
3667                                         set_bit(R5_Wantwrite, &dev->flags);
3668                                         set_bit(R5_ReWrite, &dev->flags);
3669                                         set_bit(R5_LOCKED, &dev->flags);
3670                                         s.locked++;
3671                                 } else {
3672                                         /* let's read it back */
3673                                         set_bit(R5_Wantread, &dev->flags);
3674                                         set_bit(R5_LOCKED, &dev->flags);
3675                                         s.locked++;
3676                                 }
3677                         }
3678                 }
3679
3680
3681         /* Finish reconstruct operations initiated by the expansion process */
3682         if (sh->reconstruct_state == reconstruct_state_result) {
3683                 struct stripe_head *sh_src
3684                         = get_active_stripe(conf, sh->sector, 1, 1, 1);
3685                 if (sh_src && test_bit(STRIPE_EXPAND_SOURCE, &sh_src->state)) {
3686                         /* sh cannot be written until sh_src has been read.
3687                          * so arrange for sh to be delayed a little
3688                          */
3689                         set_bit(STRIPE_DELAYED, &sh->state);
3690                         set_bit(STRIPE_HANDLE, &sh->state);
3691                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE,
3692                                               &sh_src->state))
3693                                 atomic_inc(&conf->preread_active_stripes);
3694                         release_stripe(sh_src);
3695                         goto finish;
3696                 }
3697                 if (sh_src)
3698                         release_stripe(sh_src);
3699
3700                 sh->reconstruct_state = reconstruct_state_idle;
3701                 clear_bit(STRIPE_EXPANDING, &sh->state);
3702                 for (i = conf->raid_disks; i--; ) {
3703                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
3704                         set_bit(R5_LOCKED, &sh->dev[i].flags);
3705                         s.locked++;
3706                 }
3707         }
3708
3709         if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
3710             !sh->reconstruct_state) {
3711                 /* Need to write out all blocks after computing parity */
3712                 sh->disks = conf->raid_disks;
3713                 stripe_set_idx(sh->sector, conf, 0, sh);
3714                 schedule_reconstruction(sh, &s, 1, 1);
3715         } else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
3716                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
3717                 atomic_dec(&conf->reshape_stripes);
3718                 wake_up(&conf->wait_for_overlap);
3719                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3720         }
3721
3722         if (s.expanding && s.locked == 0 &&
3723             !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
3724                 handle_stripe_expansion(conf, sh);
3725
3726 finish:
3727         /* wait for this device to become unblocked */
3728         if (unlikely(s.blocked_rdev)) {
3729                 if (conf->mddev->external)
3730                         md_wait_for_blocked_rdev(s.blocked_rdev,
3731                                                  conf->mddev);
3732                 else
3733                         /* Internal metadata will immediately
3734                          * be written by raid5d, so we don't
3735                          * need to wait here.
3736                          */
3737                         rdev_dec_pending(s.blocked_rdev,
3738                                          conf->mddev);
3739         }
3740
3741         if (s.handle_bad_blocks)
3742                 for (i = disks; i--; ) {
3743                         struct md_rdev *rdev;
3744                         struct r5dev *dev = &sh->dev[i];
3745                         if (test_and_clear_bit(R5_WriteError, &dev->flags)) {
3746                                 /* We own a safe reference to the rdev */
3747                                 rdev = conf->disks[i].rdev;
3748                                 if (!rdev_set_badblocks(rdev, sh->sector,
3749                                                         STRIPE_SECTORS, 0))
3750                                         md_error(conf->mddev, rdev);
3751                                 rdev_dec_pending(rdev, conf->mddev);
3752                         }
3753                         if (test_and_clear_bit(R5_MadeGood, &dev->flags)) {
3754                                 rdev = conf->disks[i].rdev;
3755                                 rdev_clear_badblocks(rdev, sh->sector,
3756                                                      STRIPE_SECTORS, 0);
3757                                 rdev_dec_pending(rdev, conf->mddev);
3758                         }
3759                         if (test_and_clear_bit(R5_MadeGoodRepl, &dev->flags)) {
3760                                 rdev = conf->disks[i].replacement;
3761                                 if (!rdev)
3762                                         /* rdev have been moved down */
3763                                         rdev = conf->disks[i].rdev;
3764                                 rdev_clear_badblocks(rdev, sh->sector,
3765                                                      STRIPE_SECTORS, 0);
3766                                 rdev_dec_pending(rdev, conf->mddev);
3767                         }
3768                 }
3769
3770         if (s.ops_request)
3771                 raid_run_ops(sh, s.ops_request);
3772
3773         ops_run_io(sh, &s);
3774
3775         if (s.dec_preread_active) {
3776                 /* We delay this until after ops_run_io so that if make_request
3777                  * is waiting on a flush, it won't continue until the writes
3778                  * have actually been submitted.
3779                  */
3780                 atomic_dec(&conf->preread_active_stripes);
3781                 if (atomic_read(&conf->preread_active_stripes) <
3782                     IO_THRESHOLD)
3783                         md_wakeup_thread(conf->mddev->thread);
3784         }
3785
3786         return_io(s.return_bi);
3787
3788         clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
3789 }
3790
3791 static void raid5_activate_delayed(struct r5conf *conf)
3792 {
3793         if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
3794                 while (!list_empty(&conf->delayed_list)) {
3795                         struct list_head *l = conf->delayed_list.next;
3796                         struct stripe_head *sh;
3797                         sh = list_entry(l, struct stripe_head, lru);
3798                         list_del_init(l);
3799                         clear_bit(STRIPE_DELAYED, &sh->state);
3800                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3801                                 atomic_inc(&conf->preread_active_stripes);
3802                         list_add_tail(&sh->lru, &conf->hold_list);
3803                 }
3804         }
3805 }
3806
3807 static void activate_bit_delay(struct r5conf *conf)
3808 {
3809         /* device_lock is held */
3810         struct list_head head;
3811         list_add(&head, &conf->bitmap_list);
3812         list_del_init(&conf->bitmap_list);
3813         while (!list_empty(&head)) {
3814                 struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
3815                 list_del_init(&sh->lru);
3816                 atomic_inc(&sh->count);
3817                 __release_stripe(conf, sh);
3818         }
3819 }
3820
3821 int md_raid5_congested(struct mddev *mddev, int bits)
3822 {
3823         struct r5conf *conf = mddev->private;
3824
3825         /* No difference between reads and writes.  Just check
3826          * how busy the stripe_cache is
3827          */
3828
3829         if (conf->inactive_blocked)
3830                 return 1;
3831         if (conf->quiesce)
3832                 return 1;
3833         if (list_empty_careful(&conf->inactive_list))
3834                 return 1;
3835
3836         return 0;
3837 }
3838 EXPORT_SYMBOL_GPL(md_raid5_congested);
3839
3840 static int raid5_congested(void *data, int bits)
3841 {
3842         struct mddev *mddev = data;
3843
3844         return mddev_congested(mddev, bits) ||
3845                 md_raid5_congested(mddev, bits);
3846 }
3847
3848 /* We want read requests to align with chunks where possible,
3849  * but write requests don't need to.
3850  */
3851 static int raid5_mergeable_bvec(struct request_queue *q,
3852                                 struct bvec_merge_data *bvm,
3853                                 struct bio_vec *biovec)
3854 {
3855         struct mddev *mddev = q->queuedata;
3856         sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
3857         int max;
3858         unsigned int chunk_sectors = mddev->chunk_sectors;
3859         unsigned int bio_sectors = bvm->bi_size >> 9;
3860
3861         if ((bvm->bi_rw & 1) == WRITE)
3862                 return biovec->bv_len; /* always allow writes to be mergeable */
3863
3864         if (mddev->new_chunk_sectors < mddev->chunk_sectors)
3865                 chunk_sectors = mddev->new_chunk_sectors;
3866         max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
3867         if (max < 0) max = 0;
3868         if (max <= biovec->bv_len && bio_sectors == 0)
3869                 return biovec->bv_len;
3870         else
3871                 return max;
3872 }
3873
3874
3875 static int in_chunk_boundary(struct mddev *mddev, struct bio *bio)
3876 {
3877         sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
3878         unsigned int chunk_sectors = mddev->chunk_sectors;
3879         unsigned int bio_sectors = bio_sectors(bio);
3880
3881         if (mddev->new_chunk_sectors < mddev->chunk_sectors)
3882                 chunk_sectors = mddev->new_chunk_sectors;
3883         return  chunk_sectors >=
3884                 ((sector & (chunk_sectors - 1)) + bio_sectors);
3885 }
3886
3887 /*
3888  *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
3889  *  later sampled by raid5d.
3890  */
3891 static void add_bio_to_retry(struct bio *bi,struct r5conf *conf)
3892 {
3893         unsigned long flags;
3894
3895         spin_lock_irqsave(&conf->device_lock, flags);
3896
3897         bi->bi_next = conf->retry_read_aligned_list;
3898         conf->retry_read_aligned_list = bi;
3899
3900         spin_unlock_irqrestore(&conf->device_lock, flags);
3901         md_wakeup_thread(conf->mddev->thread);
3902 }
3903
3904
3905 static struct bio *remove_bio_from_retry(struct r5conf *conf)
3906 {
3907         struct bio *bi;
3908
3909         bi = conf->retry_read_aligned;
3910         if (bi) {
3911                 conf->retry_read_aligned = NULL;
3912                 return bi;
3913         }
3914         bi = conf->retry_read_aligned_list;
3915         if(bi) {
3916                 conf->retry_read_aligned_list = bi->bi_next;
3917                 bi->bi_next = NULL;
3918                 /*
3919                  * this sets the active strip count to 1 and the processed
3920                  * strip count to zero (upper 8 bits)
3921                  */
3922                 raid5_set_bi_stripes(bi, 1); /* biased count of active stripes */
3923         }
3924
3925         return bi;
3926 }
3927
3928
3929 /*
3930  *  The "raid5_align_endio" should check if the read succeeded and if it
3931  *  did, call bio_endio on the original bio (having bio_put the new bio
3932  *  first).
3933  *  If the read failed..
3934  */
3935 static void raid5_align_endio(struct bio *bi, int error)
3936 {
3937         struct bio* raid_bi  = bi->bi_private;
3938         struct mddev *mddev;
3939         struct r5conf *conf;
3940         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
3941         struct md_rdev *rdev;
3942
3943         bio_put(bi);
3944
3945         rdev = (void*)raid_bi->bi_next;
3946         raid_bi->bi_next = NULL;
3947         mddev = rdev->mddev;
3948         conf = mddev->private;
3949
3950         rdev_dec_pending(rdev, conf->mddev);
3951
3952         if (!error && uptodate) {
3953                 trace_block_bio_complete(bdev_get_queue(raid_bi->bi_bdev),
3954                                          raid_bi, 0);
3955                 bio_endio(raid_bi, 0);
3956                 if (atomic_dec_and_test(&conf->active_aligned_reads))
3957                         wake_up(&conf->wait_for_stripe);
3958                 return;
3959         }
3960
3961
3962         pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
3963
3964         add_bio_to_retry(raid_bi, conf);
3965 }
3966
3967 static int bio_fits_rdev(struct bio *bi)
3968 {
3969         struct request_queue *q = bdev_get_queue(bi->bi_bdev);
3970
3971         if (bio_sectors(bi) > queue_max_sectors(q))
3972                 return 0;
3973         blk_recount_segments(q, bi);
3974         if (bi->bi_phys_segments > queue_max_segments(q))
3975                 return 0;
3976
3977         if (q->merge_bvec_fn)
3978                 /* it's too hard to apply the merge_bvec_fn at this stage,
3979                  * just just give up
3980                  */
3981                 return 0;
3982
3983         return 1;
3984 }
3985
3986
3987 static int chunk_aligned_read(struct mddev *mddev, struct bio * raid_bio)
3988 {
3989         struct r5conf *conf = mddev->private;
3990         int dd_idx;
3991         struct bio* align_bi;
3992         struct md_rdev *rdev;
3993         sector_t end_sector;
3994
3995         if (!in_chunk_boundary(mddev, raid_bio)) {
3996                 pr_debug("chunk_aligned_read : non aligned\n");
3997                 return 0;
3998         }
3999         /*
4000          * use bio_clone_mddev to make a copy of the bio
4001          */
4002         align_bi = bio_clone_mddev(raid_bio, GFP_NOIO, mddev);
4003         if (!align_bi)
4004                 return 0;
4005         /*
4006          *   set bi_end_io to a new function, and set bi_private to the
4007          *     original bio.
4008          */
4009         align_bi->bi_end_io  = raid5_align_endio;
4010         align_bi->bi_private = raid_bio;
4011         /*
4012          *      compute position
4013          */
4014         align_bi->bi_sector =  raid5_compute_sector(conf, raid_bio->bi_sector,
4015                                                     0,
4016                                                     &dd_idx, NULL);
4017
4018         end_sector = bio_end_sector(align_bi);
4019         rcu_read_lock();
4020         rdev = rcu_dereference(conf->disks[dd_idx].replacement);
4021         if (!rdev || test_bit(Faulty, &rdev->flags) ||
4022             rdev->recovery_offset < end_sector) {
4023                 rdev = rcu_dereference(conf->disks[dd_idx].rdev);
4024                 if (rdev &&
4025                     (test_bit(Faulty, &rdev->flags) ||
4026                     !(test_bit(In_sync, &rdev->flags) ||
4027                       rdev->recovery_offset >= end_sector)))
4028                         rdev = NULL;
4029         }
4030         if (rdev) {
4031                 sector_t first_bad;
4032                 int bad_sectors;
4033
4034                 atomic_inc(&rdev->nr_pending);
4035                 rcu_read_unlock();
4036                 raid_bio->bi_next = (void*)rdev;
4037                 align_bi->bi_bdev =  rdev->bdev;
4038                 align_bi->bi_flags &= ~(1 << BIO_SEG_VALID);
4039
4040                 if (!bio_fits_rdev(align_bi) ||
4041                     is_badblock(rdev, align_bi->bi_sector, bio_sectors(align_bi),
4042                                 &first_bad, &bad_sectors)) {
4043                         /* too big in some way, or has a known bad block */
4044                         bio_put(align_bi);
4045                         rdev_dec_pending(rdev, mddev);
4046                         return 0;
4047                 }
4048
4049                 /* No reshape active, so we can trust rdev->data_offset */
4050                 align_bi->bi_sector += rdev->data_offset;
4051
4052                 spin_lock_irq(&conf->device_lock);
4053                 wait_event_lock_irq(conf->wait_for_stripe,
4054                                     conf->quiesce == 0,
4055                                     conf->device_lock);
4056                 atomic_inc(&conf->active_aligned_reads);
4057                 spin_unlock_irq(&conf->device_lock);
4058
4059                 if (mddev->gendisk)
4060                         trace_block_bio_remap(bdev_get_queue(align_bi->bi_bdev),
4061                                               align_bi, disk_devt(mddev->gendisk),
4062                                               raid_bio->bi_sector);
4063                 generic_make_request(align_bi);
4064                 return 1;
4065         } else {
4066                 rcu_read_unlock();
4067                 bio_put(align_bi);
4068                 return 0;
4069         }
4070 }
4071
4072 /* __get_priority_stripe - get the next stripe to process
4073  *
4074  * Full stripe writes are allowed to pass preread active stripes up until
4075  * the bypass_threshold is exceeded.  In general the bypass_count
4076  * increments when the handle_list is handled before the hold_list; however, it
4077  * will not be incremented when STRIPE_IO_STARTED is sampled set signifying a
4078  * stripe with in flight i/o.  The bypass_count will be reset when the
4079  * head of the hold_list has changed, i.e. the head was promoted to the
4080  * handle_list.
4081  */
4082 static struct stripe_head *__get_priority_stripe(struct r5conf *conf)
4083 {
4084         struct stripe_head *sh;
4085
4086         pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
4087                   __func__,
4088                   list_empty(&conf->handle_list) ? "empty" : "busy",
4089                   list_empty(&conf->hold_list) ? "empty" : "busy",
4090                   atomic_read(&conf->pending_full_writes), conf->bypass_count);
4091
4092         if (!list_empty(&conf->handle_list)) {
4093                 sh = list_entry(conf->handle_list.next, typeof(*sh), lru);
4094
4095                 if (list_empty(&conf->hold_list))
4096                         conf->bypass_count = 0;
4097                 else if (!test_bit(STRIPE_IO_STARTED, &sh->state)) {
4098                         if (conf->hold_list.next == conf->last_hold)
4099                                 conf->bypass_count++;
4100                         else {
4101                                 conf->last_hold = conf->hold_list.next;
4102                                 conf->bypass_count -= conf->bypass_threshold;
4103                                 if (conf->bypass_count < 0)
4104                                         conf->bypass_count = 0;
4105                         }
4106                 }
4107         } else if (!list_empty(&conf->hold_list) &&
4108                    ((conf->bypass_threshold &&
4109                      conf->bypass_count > conf->bypass_threshold) ||
4110                     atomic_read(&conf->pending_full_writes) == 0)) {
4111                 sh = list_entry(conf->hold_list.next,
4112                                 typeof(*sh), lru);
4113                 conf->bypass_count -= conf->bypass_threshold;
4114                 if (conf->bypass_count < 0)
4115                         conf->bypass_count = 0;
4116         } else
4117                 return NULL;
4118
4119         list_del_init(&sh->lru);
4120         atomic_inc(&sh->count);
4121         BUG_ON(atomic_read(&sh->count) != 1);
4122         return sh;
4123 }
4124
4125 struct raid5_plug_cb {
4126         struct blk_plug_cb      cb;
4127         struct list_head        list;
4128 };
4129
4130 static void raid5_unplug(struct blk_plug_cb *blk_cb, bool from_schedule)
4131 {
4132         struct raid5_plug_cb *cb = container_of(
4133                 blk_cb, struct raid5_plug_cb, cb);
4134         struct stripe_head *sh;
4135         struct mddev *mddev = cb->cb.data;
4136         struct r5conf *conf = mddev->private;
4137         int cnt = 0;
4138
4139         if (cb->list.next && !list_empty(&cb->list)) {
4140                 spin_lock_irq(&conf->device_lock);
4141                 while (!list_empty(&cb->list)) {
4142                         sh = list_first_entry(&cb->list, struct stripe_head, lru);
4143                         list_del_init(&sh->lru);
4144                         /*
4145                          * avoid race release_stripe_plug() sees
4146                          * STRIPE_ON_UNPLUG_LIST clear but the stripe
4147                          * is still in our list
4148                          */
4149                         smp_mb__before_clear_bit();
4150                         clear_bit(STRIPE_ON_UNPLUG_LIST, &sh->state);
4151                         __release_stripe(conf, sh);
4152                         cnt++;
4153                 }
4154                 spin_unlock_irq(&conf->device_lock);
4155         }
4156         if (mddev->queue)
4157                 trace_block_unplug(mddev->queue, cnt, !from_schedule);
4158         kfree(cb);
4159 }
4160
4161 static void release_stripe_plug(struct mddev *mddev,
4162                                 struct stripe_head *sh)
4163 {
4164         struct blk_plug_cb *blk_cb = blk_check_plugged(
4165                 raid5_unplug, mddev,
4166                 sizeof(struct raid5_plug_cb));
4167         struct raid5_plug_cb *cb;
4168
4169         if (!blk_cb) {
4170                 release_stripe(sh);
4171                 return;
4172         }
4173
4174         cb = container_of(blk_cb, struct raid5_plug_cb, cb);
4175
4176         if (cb->list.next == NULL)
4177                 INIT_LIST_HEAD(&cb->list);
4178
4179         if (!test_and_set_bit(STRIPE_ON_UNPLUG_LIST, &sh->state))
4180                 list_add_tail(&sh->lru, &cb->list);
4181         else
4182                 release_stripe(sh);
4183 }
4184
4185 static void make_discard_request(struct mddev *mddev, struct bio *bi)
4186 {
4187         struct r5conf *conf = mddev->private;
4188         sector_t logical_sector, last_sector;
4189         struct stripe_head *sh;
4190         int remaining;
4191         int stripe_sectors;
4192
4193         if (mddev->reshape_position != MaxSector)
4194                 /* Skip discard while reshape is happening */
4195                 return;
4196
4197         logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4198         last_sector = bi->bi_sector + (bi->bi_size>>9);
4199
4200         bi->bi_next = NULL;
4201         bi->bi_phys_segments = 1; /* over-loaded to count active stripes */
4202
4203         stripe_sectors = conf->chunk_sectors *
4204                 (conf->raid_disks - conf->max_degraded);
4205         logical_sector = DIV_ROUND_UP_SECTOR_T(logical_sector,
4206                                                stripe_sectors);
4207         sector_div(last_sector, stripe_sectors);
4208
4209         logical_sector *= conf->chunk_sectors;
4210         last_sector *= conf->chunk_sectors;
4211
4212         for (; logical_sector < last_sector;
4213              logical_sector += STRIPE_SECTORS) {
4214                 DEFINE_WAIT(w);
4215                 int d;
4216         again:
4217                 sh = get_active_stripe(conf, logical_sector, 0, 0, 0);
4218                 prepare_to_wait(&conf->wait_for_overlap, &w,
4219                                 TASK_UNINTERRUPTIBLE);
4220                 set_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
4221                 if (test_bit(STRIPE_SYNCING, &sh->state)) {
4222                         release_stripe(sh);
4223                         schedule();
4224                         goto again;
4225                 }
4226                 clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
4227                 spin_lock_irq(&sh->stripe_lock);
4228                 for (d = 0; d < conf->raid_disks; d++) {
4229                         if (d == sh->pd_idx || d == sh->qd_idx)
4230                                 continue;
4231                         if (sh->dev[d].towrite || sh->dev[d].toread) {
4232                                 set_bit(R5_Overlap, &sh->dev[d].flags);
4233                                 spin_unlock_irq(&sh->stripe_lock);
4234                                 release_stripe(sh);
4235                                 schedule();
4236                                 goto again;
4237                         }
4238                 }
4239                 set_bit(STRIPE_DISCARD, &sh->state);
4240                 finish_wait(&conf->wait_for_overlap, &w);
4241                 for (d = 0; d < conf->raid_disks; d++) {
4242                         if (d == sh->pd_idx || d == sh->qd_idx)
4243                                 continue;
4244                         sh->dev[d].towrite = bi;
4245                         set_bit(R5_OVERWRITE, &sh->dev[d].flags);
4246                         raid5_inc_bi_active_stripes(bi);
4247                 }
4248                 spin_unlock_irq(&sh->stripe_lock);
4249                 if (conf->mddev->bitmap) {
4250                         for (d = 0;
4251                              d < conf->raid_disks - conf->max_degraded;
4252                              d++)
4253                                 bitmap_startwrite(mddev->bitmap,
4254                                                   sh->sector,
4255                                                   STRIPE_SECTORS,
4256                                                   0);
4257                         sh->bm_seq = conf->seq_flush + 1;
4258                         set_bit(STRIPE_BIT_DELAY, &sh->state);
4259                 }
4260
4261                 set_bit(STRIPE_HANDLE, &sh->state);
4262                 clear_bit(STRIPE_DELAYED, &sh->state);
4263                 if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4264                         atomic_inc(&conf->preread_active_stripes);
4265                 release_stripe_plug(mddev, sh);
4266         }
4267
4268         remaining = raid5_dec_bi_active_stripes(bi);
4269         if (remaining == 0) {
4270                 md_write_end(mddev);
4271                 bio_endio(bi, 0);
4272         }
4273 }
4274
4275 static void make_request(struct mddev *mddev, struct bio * bi)
4276 {
4277         struct r5conf *conf = mddev->private;
4278         int dd_idx;
4279         sector_t new_sector;
4280         sector_t logical_sector, last_sector;
4281         struct stripe_head *sh;
4282         const int rw = bio_data_dir(bi);
4283         int remaining;
4284
4285         if (unlikely(bi->bi_rw & REQ_FLUSH)) {
4286                 md_flush_request(mddev, bi);
4287                 return;
4288         }
4289
4290         md_write_start(mddev, bi);
4291
4292         if (rw == READ &&
4293              mddev->reshape_position == MaxSector &&
4294              chunk_aligned_read(mddev,bi))
4295                 return;
4296
4297         if (unlikely(bi->bi_rw & REQ_DISCARD)) {
4298                 make_discard_request(mddev, bi);
4299                 return;
4300         }
4301
4302         logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4303         last_sector = bio_end_sector(bi);
4304         bi->bi_next = NULL;
4305         bi->bi_phys_segments = 1;       /* over-loaded to count active stripes */
4306
4307         for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
4308                 DEFINE_WAIT(w);
4309                 int previous;
4310
4311         retry:
4312                 previous = 0;
4313                 prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
4314                 if (unlikely(conf->reshape_progress != MaxSector)) {
4315                         /* spinlock is needed as reshape_progress may be
4316                          * 64bit on a 32bit platform, and so it might be
4317                          * possible to see a half-updated value
4318                          * Of course reshape_progress could change after
4319                          * the lock is dropped, so once we get a reference
4320                          * to the stripe that we think it is, we will have
4321                          * to check again.
4322                          */
4323                         spin_lock_irq(&conf->device_lock);
4324                         if (mddev->reshape_backwards
4325                             ? logical_sector < conf->reshape_progress
4326                             : logical_sector >= conf->reshape_progress) {
4327                                 previous = 1;
4328                         } else {
4329                                 if (mddev->reshape_backwards
4330                                     ? logical_sector < conf->reshape_safe
4331                                     : logical_sector >= conf->reshape_safe) {
4332                                         spin_unlock_irq(&conf->device_lock);
4333                                         schedule();
4334                                         goto retry;
4335                                 }
4336                         }
4337                         spin_unlock_irq(&conf->device_lock);
4338                 }
4339
4340                 new_sector = raid5_compute_sector(conf, logical_sector,
4341                                                   previous,
4342                                                   &dd_idx, NULL);
4343                 pr_debug("raid456: make_request, sector %llu logical %llu\n",
4344                         (unsigned long long)new_sector,
4345                         (unsigned long long)logical_sector);
4346
4347                 sh = get_active_stripe(conf, new_sector, previous,
4348                                        (bi->bi_rw&RWA_MASK), 0);
4349                 if (sh) {
4350                         if (unlikely(previous)) {
4351                                 /* expansion might have moved on while waiting for a
4352                                  * stripe, so we must do the range check again.
4353                                  * Expansion could still move past after this
4354                                  * test, but as we are holding a reference to
4355                                  * 'sh', we know that if that happens,
4356                                  *  STRIPE_EXPANDING will get set and the expansion
4357                                  * won't proceed until we finish with the stripe.
4358                                  */
4359                                 int must_retry = 0;
4360                                 spin_lock_irq(&conf->device_lock);
4361                                 if (mddev->reshape_backwards
4362                                     ? logical_sector >= conf->reshape_progress
4363                                     : logical_sector < conf->reshape_progress)
4364                                         /* mismatch, need to try again */
4365                                         must_retry = 1;
4366                                 spin_unlock_irq(&conf->device_lock);
4367                                 if (must_retry) {
4368                                         release_stripe(sh);
4369                                         schedule();
4370                                         goto retry;
4371                                 }
4372                         }
4373
4374                         if (rw == WRITE &&
4375                             logical_sector >= mddev->suspend_lo &&
4376                             logical_sector < mddev->suspend_hi) {
4377                                 release_stripe(sh);
4378                                 /* As the suspend_* range is controlled by
4379                                  * userspace, we want an interruptible
4380                                  * wait.
4381                                  */
4382                                 flush_signals(current);
4383                                 prepare_to_wait(&conf->wait_for_overlap,
4384                                                 &w, TASK_INTERRUPTIBLE);
4385                                 if (logical_sector >= mddev->suspend_lo &&
4386                                     logical_sector < mddev->suspend_hi)
4387                                         schedule();
4388                                 goto retry;
4389                         }
4390
4391                         if (test_bit(STRIPE_EXPANDING, &sh->state) ||
4392                             !add_stripe_bio(sh, bi, dd_idx, rw)) {
4393                                 /* Stripe is busy expanding or
4394                                  * add failed due to overlap.  Flush everything
4395                                  * and wait a while
4396                                  */
4397                                 md_wakeup_thread(mddev->thread);
4398                                 release_stripe(sh);
4399                                 schedule();
4400                                 goto retry;
4401                         }
4402                         finish_wait(&conf->wait_for_overlap, &w);
4403                         set_bit(STRIPE_HANDLE, &sh->state);
4404                         clear_bit(STRIPE_DELAYED, &sh->state);
4405                         if ((bi->bi_rw & REQ_SYNC) &&
4406                             !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4407                                 atomic_inc(&conf->preread_active_stripes);
4408                         release_stripe_plug(mddev, sh);
4409                 } else {
4410                         /* cannot get stripe for read-ahead, just give-up */
4411                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
4412                         finish_wait(&conf->wait_for_overlap, &w);
4413                         break;
4414                 }
4415         }
4416
4417         remaining = raid5_dec_bi_active_stripes(bi);
4418         if (remaining == 0) {
4419
4420                 if ( rw == WRITE )
4421                         md_write_end(mddev);
4422
4423                 trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
4424                                          bi, 0);
4425                 bio_endio(bi, 0);
4426         }
4427 }
4428
4429 static sector_t raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks);
4430
4431 static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *skipped)
4432 {
4433         /* reshaping is quite different to recovery/resync so it is
4434          * handled quite separately ... here.
4435          *
4436          * On each call to sync_request, we gather one chunk worth of
4437          * destination stripes and flag them as expanding.
4438          * Then we find all the source stripes and request reads.
4439          * As the reads complete, handle_stripe will copy the data
4440          * into the destination stripe and release that stripe.
4441          */
4442         struct r5conf *conf = mddev->private;
4443         struct stripe_head *sh;
4444         sector_t first_sector, last_sector;
4445         int raid_disks = conf->previous_raid_disks;
4446         int data_disks = raid_disks - conf->max_degraded;
4447         int new_data_disks = conf->raid_disks - conf->max_degraded;
4448         int i;
4449         int dd_idx;
4450         sector_t writepos, readpos, safepos;
4451         sector_t stripe_addr;
4452         int reshape_sectors;
4453         struct list_head stripes;
4454
4455         if (sector_nr == 0) {
4456                 /* If restarting in the middle, skip the initial sectors */
4457                 if (mddev->reshape_backwards &&
4458                     conf->reshape_progress < raid5_size(mddev, 0, 0)) {
4459                         sector_nr = raid5_size(mddev, 0, 0)
4460                                 - conf->reshape_progress;
4461                 } else if (!mddev->reshape_backwards &&
4462                            conf->reshape_progress > 0)
4463                         sector_nr = conf->reshape_progress;
4464                 sector_div(sector_nr, new_data_disks);
4465                 if (sector_nr) {
4466                         mddev->curr_resync_completed = sector_nr;
4467                         sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4468                         *skipped = 1;
4469                         return sector_nr;
4470                 }
4471         }
4472
4473         /* We need to process a full chunk at a time.
4474          * If old and new chunk sizes differ, we need to process the
4475          * largest of these
4476          */
4477         if (mddev->new_chunk_sectors > mddev->chunk_sectors)
4478                 reshape_sectors = mddev->new_chunk_sectors;
4479         else
4480                 reshape_sectors = mddev->chunk_sectors;
4481
4482         /* We update the metadata at least every 10 seconds, or when
4483          * the data about to be copied would over-write the source of
4484          * the data at the front of the range.  i.e. one new_stripe
4485          * along from reshape_progress new_maps to after where
4486          * reshape_safe old_maps to
4487          */
4488         writepos = conf->reshape_progress;
4489         sector_div(writepos, new_data_disks);
4490         readpos = conf->reshape_progress;
4491         sector_div(readpos, data_disks);
4492         safepos = conf->reshape_safe;
4493         sector_div(safepos, data_disks);
4494         if (mddev->reshape_backwards) {
4495                 writepos -= min_t(sector_t, reshape_sectors, writepos);
4496                 readpos += reshape_sectors;
4497                 safepos += reshape_sectors;
4498         } else {
4499                 writepos += reshape_sectors;
4500                 readpos -= min_t(sector_t, reshape_sectors, readpos);
4501                 safepos -= min_t(sector_t, reshape_sectors, safepos);
4502         }
4503
4504         /* Having calculated the 'writepos' possibly use it
4505          * to set 'stripe_addr' which is where we will write to.
4506          */
4507         if (mddev->reshape_backwards) {
4508                 BUG_ON(conf->reshape_progress == 0);
4509                 stripe_addr = writepos;
4510                 BUG_ON((mddev->dev_sectors &
4511                         ~((sector_t)reshape_sectors - 1))
4512                        - reshape_sectors - stripe_addr
4513                        != sector_nr);
4514         } else {
4515                 BUG_ON(writepos != sector_nr + reshape_sectors);
4516                 stripe_addr = sector_nr;
4517         }
4518
4519         /* 'writepos' is the most advanced device address we might write.
4520          * 'readpos' is the least advanced device address we might read.
4521          * 'safepos' is the least address recorded in the metadata as having
4522          *     been reshaped.
4523          * If there is a min_offset_diff, these are adjusted either by
4524          * increasing the safepos/readpos if diff is negative, or
4525          * increasing writepos if diff is positive.
4526          * If 'readpos' is then behind 'writepos', there is no way that we can
4527          * ensure safety in the face of a crash - that must be done by userspace
4528          * making a backup of the data.  So in that case there is no particular
4529          * rush to update metadata.
4530          * Otherwise if 'safepos' is behind 'writepos', then we really need to
4531          * update the metadata to advance 'safepos' to match 'readpos' so that
4532          * we can be safe in the event of a crash.
4533          * So we insist on updating metadata if safepos is behind writepos and
4534          * readpos is beyond writepos.
4535          * In any case, update the metadata every 10 seconds.
4536          * Maybe that number should be configurable, but I'm not sure it is
4537          * worth it.... maybe it could be a multiple of safemode_delay???
4538          */
4539         if (conf->min_offset_diff < 0) {
4540                 safepos += -conf->min_offset_diff;
4541                 readpos += -conf->min_offset_diff;
4542         } else
4543                 writepos += conf->min_offset_diff;
4544
4545         if ((mddev->reshape_backwards
4546              ? (safepos > writepos && readpos < writepos)
4547              : (safepos < writepos && readpos > writepos)) ||
4548             time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
4549                 /* Cannot proceed until we've updated the superblock... */
4550                 wait_event(conf->wait_for_overlap,
4551                            atomic_read(&conf->reshape_stripes)==0);
4552                 mddev->reshape_position = conf->reshape_progress;
4553                 mddev->curr_resync_completed = sector_nr;
4554                 conf->reshape_checkpoint = jiffies;
4555                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
4556                 md_wakeup_thread(mddev->thread);
4557                 wait_event(mddev->sb_wait, mddev->flags == 0 ||
4558                            kthread_should_stop());
4559                 spin_lock_irq(&conf->device_lock);
4560                 conf->reshape_safe = mddev->reshape_position;
4561                 spin_unlock_irq(&conf->device_lock);
4562                 wake_up(&conf->wait_for_overlap);
4563                 sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4564         }
4565
4566         INIT_LIST_HEAD(&stripes);
4567         for (i = 0; i < reshape_sectors; i += STRIPE_SECTORS) {
4568                 int j;
4569                 int skipped_disk = 0;
4570                 sh = get_active_stripe(conf, stripe_addr+i, 0, 0, 1);
4571                 set_bit(STRIPE_EXPANDING, &sh->state);
4572                 atomic_inc(&conf->reshape_stripes);
4573                 /* If any of this stripe is beyond the end of the old
4574                  * array, then we need to zero those blocks
4575                  */
4576                 for (j=sh->disks; j--;) {
4577                         sector_t s;
4578                         if (j == sh->pd_idx)
4579                                 continue;
4580                         if (conf->level == 6 &&
4581                             j == sh->qd_idx)
4582                                 continue;
4583                         s = compute_blocknr(sh, j, 0);
4584                         if (s < raid5_size(mddev, 0, 0)) {
4585                                 skipped_disk = 1;
4586                                 continue;
4587                         }
4588                         memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
4589                         set_bit(R5_Expanded, &sh->dev[j].flags);
4590                         set_bit(R5_UPTODATE, &sh->dev[j].flags);
4591                 }
4592                 if (!skipped_disk) {
4593                         set_bit(STRIPE_EXPAND_READY, &sh->state);
4594                         set_bit(STRIPE_HANDLE, &sh->state);
4595                 }
4596                 list_add(&sh->lru, &stripes);
4597         }
4598         spin_lock_irq(&conf->device_lock);
4599         if (mddev->reshape_backwards)
4600                 conf->reshape_progress -= reshape_sectors * new_data_disks;
4601         else
4602                 conf->reshape_progress += reshape_sectors * new_data_disks;
4603         spin_unlock_irq(&conf->device_lock);
4604         /* Ok, those stripe are ready. We can start scheduling
4605          * reads on the source stripes.
4606          * The source stripes are determined by mapping the first and last
4607          * block on the destination stripes.
4608          */
4609         first_sector =
4610                 raid5_compute_sector(conf, stripe_addr*(new_data_disks),
4611                                      1, &dd_idx, NULL);
4612         last_sector =
4613                 raid5_compute_sector(conf, ((stripe_addr+reshape_sectors)
4614                                             * new_data_disks - 1),
4615                                      1, &dd_idx, NULL);
4616         if (last_sector >= mddev->dev_sectors)
4617                 last_sector = mddev->dev_sectors - 1;
4618         while (first_sector <= last_sector) {
4619                 sh = get_active_stripe(conf, first_sector, 1, 0, 1);
4620                 set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
4621                 set_bit(STRIPE_HANDLE, &sh->state);
4622                 release_stripe(sh);
4623                 first_sector += STRIPE_SECTORS;
4624         }
4625         /* Now that the sources are clearly marked, we can release
4626          * the destination stripes
4627          */
4628         while (!list_empty(&stripes)) {
4629                 sh = list_entry(stripes.next, struct stripe_head, lru);
4630                 list_del_init(&sh->lru);
4631                 release_stripe(sh);
4632         }
4633         /* If this takes us to the resync_max point where we have to pause,
4634          * then we need to write out the superblock.
4635          */
4636         sector_nr += reshape_sectors;
4637         if ((sector_nr - mddev->curr_resync_completed) * 2
4638             >= mddev->resync_max - mddev->curr_resync_completed) {
4639                 /* Cannot proceed until we've updated the superblock... */
4640                 wait_event(conf->wait_for_overlap,
4641                            atomic_read(&conf->reshape_stripes) == 0);
4642                 mddev->reshape_position = conf->reshape_progress;
4643                 mddev->curr_resync_completed = sector_nr;
4644                 conf->reshape_checkpoint = jiffies;
4645                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
4646                 md_wakeup_thread(mddev->thread);
4647                 wait_event(mddev->sb_wait,
4648                            !test_bit(MD_CHANGE_DEVS, &mddev->flags)
4649                            || kthread_should_stop());
4650                 spin_lock_irq(&conf->device_lock);
4651                 conf->reshape_safe = mddev->reshape_position;
4652                 spin_unlock_irq(&conf->device_lock);
4653                 wake_up(&conf->wait_for_overlap);
4654                 sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4655         }
4656         return reshape_sectors;
4657 }
4658
4659 /* FIXME go_faster isn't used */
4660 static inline sector_t sync_request(struct mddev *mddev, sector_t sector_nr, int *skipped, int go_faster)
4661 {
4662         struct r5conf *conf = mddev->private;
4663         struct stripe_head *sh;
4664         sector_t max_sector = mddev->dev_sectors;
4665         sector_t sync_blocks;
4666         int still_degraded = 0;
4667         int i;
4668
4669         if (sector_nr >= max_sector) {
4670                 /* just being told to finish up .. nothing much to do */
4671
4672                 if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
4673                         end_reshape(conf);
4674                         return 0;
4675                 }
4676
4677                 if (mddev->curr_resync < max_sector) /* aborted */
4678                         bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
4679                                         &sync_blocks, 1);
4680                 else /* completed sync */
4681                         conf->fullsync = 0;
4682                 bitmap_close_sync(mddev->bitmap);
4683
4684                 return 0;
4685         }
4686
4687         /* Allow raid5_quiesce to complete */
4688         wait_event(conf->wait_for_overlap, conf->quiesce != 2);
4689
4690         if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
4691                 return reshape_request(mddev, sector_nr, skipped);
4692
4693         /* No need to check resync_max as we never do more than one
4694          * stripe, and as resync_max will always be on a chunk boundary,
4695          * if the check in md_do_sync didn't fire, there is no chance
4696          * of overstepping resync_max here
4697          */
4698
4699         /* if there is too many failed drives and we are trying
4700          * to resync, then assert that we are finished, because there is
4701          * nothing we can do.
4702          */
4703         if (mddev->degraded >= conf->max_degraded &&
4704             test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
4705                 sector_t rv = mddev->dev_sectors - sector_nr;
4706                 *skipped = 1;
4707                 return rv;
4708         }
4709         if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
4710             !conf->fullsync &&
4711             !bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
4712             sync_blocks >= STRIPE_SECTORS) {
4713                 /* we can skip this block, and probably more */
4714                 sync_blocks /= STRIPE_SECTORS;
4715                 *skipped = 1;
4716                 return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
4717         }
4718
4719         bitmap_cond_end_sync(mddev->bitmap, sector_nr);
4720
4721         sh = get_active_stripe(conf, sector_nr, 0, 1, 0);
4722         if (sh == NULL) {
4723                 sh = get_active_stripe(conf, sector_nr, 0, 0, 0);
4724                 /* make sure we don't swamp the stripe cache if someone else
4725                  * is trying to get access
4726                  */
4727                 schedule_timeout_uninterruptible(1);
4728         }
4729         /* Need to check if array will still be degraded after recovery/resync
4730          * We don't need to check the 'failed' flag as when that gets set,
4731          * recovery aborts.
4732          */
4733         for (i = 0; i < conf->raid_disks; i++)
4734                 if (conf->disks[i].rdev == NULL)
4735                         still_degraded = 1;
4736
4737         bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
4738
4739         set_bit(STRIPE_SYNC_REQUESTED, &sh->state);
4740
4741         handle_stripe(sh);
4742         release_stripe(sh);
4743
4744         return STRIPE_SECTORS;
4745 }
4746
4747 static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
4748 {
4749         /* We may not be able to submit a whole bio at once as there
4750          * may not be enough stripe_heads available.
4751          * We cannot pre-allocate enough stripe_heads as we may need
4752          * more than exist in the cache (if we allow ever large chunks).
4753          * So we do one stripe head at a time and record in
4754          * ->bi_hw_segments how many have been done.
4755          *
4756          * We *know* that this entire raid_bio is in one chunk, so
4757          * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
4758          */
4759         struct stripe_head *sh;
4760         int dd_idx;
4761         sector_t sector, logical_sector, last_sector;
4762         int scnt = 0;
4763         int remaining;
4764         int handled = 0;
4765
4766         logical_sector = raid_bio->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4767         sector = raid5_compute_sector(conf, logical_sector,
4768                                       0, &dd_idx, NULL);
4769         last_sector = bio_end_sector(raid_bio);
4770
4771         for (; logical_sector < last_sector;
4772              logical_sector += STRIPE_SECTORS,
4773                      sector += STRIPE_SECTORS,
4774                      scnt++) {
4775
4776                 if (scnt < raid5_bi_processed_stripes(raid_bio))
4777                         /* already done this stripe */
4778                         continue;
4779
4780                 sh = get_active_stripe(conf, sector, 0, 1, 0);
4781
4782                 if (!sh) {
4783                         /* failed to get a stripe - must wait */
4784                         raid5_set_bi_processed_stripes(raid_bio, scnt);
4785                         conf->retry_read_aligned = raid_bio;
4786                         return handled;
4787                 }
4788
4789                 if (!add_stripe_bio(sh, raid_bio, dd_idx, 0)) {
4790                         release_stripe(sh);
4791                         raid5_set_bi_processed_stripes(raid_bio, scnt);
4792                         conf->retry_read_aligned = raid_bio;
4793                         return handled;
4794                 }
4795
4796                 set_bit(R5_ReadNoMerge, &sh->dev[dd_idx].flags);
4797                 handle_stripe(sh);
4798                 release_stripe(sh);
4799                 handled++;
4800         }
4801         remaining = raid5_dec_bi_active_stripes(raid_bio);
4802         if (remaining == 0) {
4803                 trace_block_bio_complete(bdev_get_queue(raid_bio->bi_bdev),
4804                                          raid_bio, 0);
4805                 bio_endio(raid_bio, 0);
4806         }
4807         if (atomic_dec_and_test(&conf->active_aligned_reads))
4808                 wake_up(&conf->wait_for_stripe);
4809         return handled;
4810 }
4811
4812 #define MAX_STRIPE_BATCH 8
4813 static int handle_active_stripes(struct r5conf *conf)
4814 {
4815         struct stripe_head *batch[MAX_STRIPE_BATCH], *sh;
4816         int i, batch_size = 0;
4817
4818         while (batch_size < MAX_STRIPE_BATCH &&
4819                         (sh = __get_priority_stripe(conf)) != NULL)
4820                 batch[batch_size++] = sh;
4821
4822         if (batch_size == 0)
4823                 return batch_size;
4824         spin_unlock_irq(&conf->device_lock);
4825
4826         for (i = 0; i < batch_size; i++)
4827                 handle_stripe(batch[i]);
4828
4829         cond_resched();
4830
4831         spin_lock_irq(&conf->device_lock);
4832         for (i = 0; i < batch_size; i++)
4833                 __release_stripe(conf, batch[i]);
4834         return batch_size;
4835 }
4836
4837 /*
4838  * This is our raid5 kernel thread.
4839  *
4840  * We scan the hash table for stripes which can be handled now.
4841  * During the scan, completed stripes are saved for us by the interrupt
4842  * handler, so that they will not have to wait for our next wakeup.
4843  */
4844 static void raid5d(struct md_thread *thread)
4845 {
4846         struct mddev *mddev = thread->mddev;
4847         struct r5conf *conf = mddev->private;
4848         int handled;
4849         struct blk_plug plug;
4850
4851         pr_debug("+++ raid5d active\n");
4852
4853         md_check_recovery(mddev);
4854
4855         blk_start_plug(&plug);
4856         handled = 0;
4857         spin_lock_irq(&conf->device_lock);
4858         while (1) {
4859                 struct bio *bio;
4860                 int batch_size;
4861
4862                 if (
4863                     !list_empty(&conf->bitmap_list)) {
4864                         /* Now is a good time to flush some bitmap updates */
4865                         conf->seq_flush++;
4866                         spin_unlock_irq(&conf->device_lock);
4867                         bitmap_unplug(mddev->bitmap);
4868                         spin_lock_irq(&conf->device_lock);
4869                         conf->seq_write = conf->seq_flush;
4870                         activate_bit_delay(conf);
4871                 }
4872                 raid5_activate_delayed(conf);
4873
4874                 while ((bio = remove_bio_from_retry(conf))) {
4875                         int ok;
4876                         spin_unlock_irq(&conf->device_lock);
4877                         ok = retry_aligned_read(conf, bio);
4878                         spin_lock_irq(&conf->device_lock);
4879                         if (!ok)
4880                                 break;
4881                         handled++;
4882                 }
4883
4884                 batch_size = handle_active_stripes(conf);
4885                 if (!batch_size)
4886                         break;
4887                 handled += batch_size;
4888
4889                 if (mddev->flags & ~(1<<MD_CHANGE_PENDING)) {
4890                         spin_unlock_irq(&conf->device_lock);
4891                         md_check_recovery(mddev);
4892                         spin_lock_irq(&conf->device_lock);
4893                 }
4894         }
4895         pr_debug("%d stripes handled\n", handled);
4896
4897         spin_unlock_irq(&conf->device_lock);
4898
4899         async_tx_issue_pending_all();
4900         blk_finish_plug(&plug);
4901
4902         pr_debug("--- raid5d inactive\n");
4903 }
4904
4905 static ssize_t
4906 raid5_show_stripe_cache_size(struct mddev *mddev, char *page)
4907 {
4908         struct r5conf *conf = mddev->private;
4909         if (conf)
4910                 return sprintf(page, "%d\n", conf->max_nr_stripes);
4911         else
4912                 return 0;
4913 }
4914
4915 int
4916 raid5_set_cache_size(struct mddev *mddev, int size)
4917 {
4918         struct r5conf *conf = mddev->private;
4919         int err;
4920
4921         if (size <= 16 || size > 32768)
4922                 return -EINVAL;
4923         while (size < conf->max_nr_stripes) {
4924                 if (drop_one_stripe(conf))
4925                         conf->max_nr_stripes--;
4926                 else
4927                         break;
4928         }
4929         err = md_allow_write(mddev);
4930         if (err)
4931                 return err;
4932         while (size > conf->max_nr_stripes) {
4933                 if (grow_one_stripe(conf))
4934                         conf->max_nr_stripes++;
4935                 else break;
4936         }
4937         return 0;
4938 }
4939 EXPORT_SYMBOL(raid5_set_cache_size);
4940
4941 static ssize_t
4942 raid5_store_stripe_cache_size(struct mddev *mddev, const char *page, size_t len)
4943 {
4944         struct r5conf *conf = mddev->private;
4945         unsigned long new;
4946         int err;
4947
4948         if (len >= PAGE_SIZE)
4949                 return -EINVAL;
4950         if (!conf)
4951                 return -ENODEV;
4952
4953         if (strict_strtoul(page, 10, &new))
4954                 return -EINVAL;
4955         err = raid5_set_cache_size(mddev, new);
4956         if (err)
4957                 return err;
4958         return len;
4959 }
4960
4961 static struct md_sysfs_entry
4962 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
4963                                 raid5_show_stripe_cache_size,
4964                                 raid5_store_stripe_cache_size);
4965
4966 static ssize_t
4967 raid5_show_preread_threshold(struct mddev *mddev, char *page)
4968 {
4969         struct r5conf *conf = mddev->private;
4970         if (conf)
4971                 return sprintf(page, "%d\n", conf->bypass_threshold);
4972         else
4973                 return 0;
4974 }
4975
4976 static ssize_t
4977 raid5_store_preread_threshold(struct mddev *mddev, const char *page, size_t len)
4978 {
4979         struct r5conf *conf = mddev->private;
4980         unsigned long new;
4981         if (len >= PAGE_SIZE)
4982                 return -EINVAL;
4983         if (!conf)
4984                 return -ENODEV;
4985
4986         if (strict_strtoul(page, 10, &new))
4987                 return -EINVAL;
4988         if (new > conf->max_nr_stripes)
4989                 return -EINVAL;
4990         conf->bypass_threshold = new;
4991         return len;
4992 }
4993
4994 static struct md_sysfs_entry
4995 raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold,
4996                                         S_IRUGO | S_IWUSR,
4997                                         raid5_show_preread_threshold,
4998                                         raid5_store_preread_threshold);
4999
5000 static ssize_t
5001 stripe_cache_active_show(struct mddev *mddev, char *page)
5002 {
5003         struct r5conf *conf = mddev->private;
5004         if (conf)
5005                 return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
5006         else
5007                 return 0;
5008 }
5009
5010 static struct md_sysfs_entry
5011 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
5012
5013 static struct attribute *raid5_attrs[] =  {
5014         &raid5_stripecache_size.attr,
5015         &raid5_stripecache_active.attr,
5016         &raid5_preread_bypass_threshold.attr,
5017         NULL,
5018 };
5019 static struct attribute_group raid5_attrs_group = {
5020         .name = NULL,
5021         .attrs = raid5_attrs,
5022 };
5023
5024 static sector_t
5025 raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks)
5026 {
5027         struct r5conf *conf = mddev->private;
5028
5029         if (!sectors)
5030                 sectors = mddev->dev_sectors;
5031         if (!raid_disks)
5032                 /* size is defined by the smallest of previous and new size */
5033                 raid_disks = min(conf->raid_disks, conf->previous_raid_disks);
5034
5035         sectors &= ~((sector_t)mddev->chunk_sectors - 1);
5036         sectors &= ~((sector_t)mddev->new_chunk_sectors - 1);
5037         return sectors * (raid_disks - conf->max_degraded);
5038 }
5039
5040 static void free_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
5041 {
5042         safe_put_page(percpu->spare_page);
5043         kfree(percpu->scribble);
5044         percpu->spare_page = NULL;
5045         percpu->scribble = NULL;
5046 }
5047
5048 static int alloc_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
5049 {
5050         if (conf->level == 6 && !percpu->spare_page)
5051                 percpu->spare_page = alloc_page(GFP_KERNEL);
5052         if (!percpu->scribble)
5053                 percpu->scribble = kmalloc(conf->scribble_len, GFP_KERNEL);
5054
5055         if (!percpu->scribble || (conf->level == 6 && !percpu->spare_page)) {
5056                 free_scratch_buffer(conf, percpu);
5057                 return -ENOMEM;
5058         }
5059
5060         return 0;
5061 }
5062
5063 static void raid5_free_percpu(struct r5conf *conf)
5064 {
5065         unsigned long cpu;
5066
5067         if (!conf->percpu)
5068                 return;
5069
5070 #ifdef CONFIG_HOTPLUG_CPU
5071         unregister_cpu_notifier(&conf->cpu_notify);
5072 #endif
5073
5074         get_online_cpus();
5075         for_each_possible_cpu(cpu)
5076                 free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
5077         put_online_cpus();
5078
5079         free_percpu(conf->percpu);
5080 }
5081
5082 static void free_conf(struct r5conf *conf)
5083 {
5084         shrink_stripes(conf);
5085         raid5_free_percpu(conf);
5086         kfree(conf->disks);
5087         kfree(conf->stripe_hashtbl);
5088         kfree(conf);
5089 }
5090
5091 #ifdef CONFIG_HOTPLUG_CPU
5092 static int raid456_cpu_notify(struct notifier_block *nfb, unsigned long action,
5093                               void *hcpu)
5094 {
5095         struct r5conf *conf = container_of(nfb, struct r5conf, cpu_notify);
5096         long cpu = (long)hcpu;
5097         struct raid5_percpu *percpu = per_cpu_ptr(conf->percpu, cpu);
5098
5099         switch (action) {
5100         case CPU_UP_PREPARE:
5101         case CPU_UP_PREPARE_FROZEN:
5102                 if (alloc_scratch_buffer(conf, percpu)) {
5103                         pr_err("%s: failed memory allocation for cpu%ld\n",
5104                                __func__, cpu);
5105                         return notifier_from_errno(-ENOMEM);
5106                 }
5107                 break;
5108         case CPU_DEAD:
5109         case CPU_DEAD_FROZEN:
5110                 free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
5111                 break;
5112         default:
5113                 break;
5114         }
5115         return NOTIFY_OK;
5116 }
5117 #endif
5118
5119 static int raid5_alloc_percpu(struct r5conf *conf)
5120 {
5121         unsigned long cpu;
5122         int err = 0;
5123
5124         conf->percpu = alloc_percpu(struct raid5_percpu);
5125         if (!conf->percpu)
5126                 return -ENOMEM;
5127
5128 #ifdef CONFIG_HOTPLUG_CPU
5129         conf->cpu_notify.notifier_call = raid456_cpu_notify;
5130         conf->cpu_notify.priority = 0;
5131         err = register_cpu_notifier(&conf->cpu_notify);
5132         if (err)
5133                 return err;
5134 #endif
5135
5136         get_online_cpus();
5137         for_each_present_cpu(cpu) {
5138                 err = alloc_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
5139                 if (err) {
5140                         pr_err("%s: failed memory allocation for cpu%ld\n",
5141                                __func__, cpu);
5142                         break;
5143                 }
5144         }
5145         put_online_cpus();
5146
5147         return err;
5148 }
5149
5150 static struct r5conf *setup_conf(struct mddev *mddev)
5151 {
5152         struct r5conf *conf;
5153         int raid_disk, memory, max_disks;
5154         struct md_rdev *rdev;
5155         struct disk_info *disk;
5156         char pers_name[6];
5157
5158         if (mddev->new_level != 5
5159             && mddev->new_level != 4
5160             && mddev->new_level != 6) {
5161                 printk(KERN_ERR "md/raid:%s: raid level not set to 4/5/6 (%d)\n",
5162                        mdname(mddev), mddev->new_level);
5163                 return ERR_PTR(-EIO);
5164         }
5165         if ((mddev->new_level == 5
5166              && !algorithm_valid_raid5(mddev->new_layout)) ||
5167             (mddev->new_level == 6
5168              && !algorithm_valid_raid6(mddev->new_layout))) {
5169                 printk(KERN_ERR "md/raid:%s: layout %d not supported\n",
5170                        mdname(mddev), mddev->new_layout);
5171                 return ERR_PTR(-EIO);
5172         }
5173         if (mddev->new_level == 6 && mddev->raid_disks < 4) {
5174                 printk(KERN_ERR "md/raid:%s: not enough configured devices (%d, minimum 4)\n",
5175                        mdname(mddev), mddev->raid_disks);
5176                 return ERR_PTR(-EINVAL);
5177         }
5178
5179         if (!mddev->new_chunk_sectors ||
5180             (mddev->new_chunk_sectors << 9) % PAGE_SIZE ||
5181             !is_power_of_2(mddev->new_chunk_sectors)) {
5182                 printk(KERN_ERR "md/raid:%s: invalid chunk size %d\n",
5183                        mdname(mddev), mddev->new_chunk_sectors << 9);
5184                 return ERR_PTR(-EINVAL);
5185         }
5186
5187         conf = kzalloc(sizeof(struct r5conf), GFP_KERNEL);
5188         if (conf == NULL)
5189                 goto abort;
5190         spin_lock_init(&conf->device_lock);
5191         init_waitqueue_head(&conf->wait_for_stripe);
5192         init_waitqueue_head(&conf->wait_for_overlap);
5193         INIT_LIST_HEAD(&conf->handle_list);
5194         INIT_LIST_HEAD(&conf->hold_list);
5195         INIT_LIST_HEAD(&conf->delayed_list);
5196         INIT_LIST_HEAD(&conf->bitmap_list);
5197         INIT_LIST_HEAD(&conf->inactive_list);
5198         atomic_set(&conf->active_stripes, 0);
5199         atomic_set(&conf->preread_active_stripes, 0);
5200         atomic_set(&conf->active_aligned_reads, 0);
5201         conf->bypass_threshold = BYPASS_THRESHOLD;
5202         conf->recovery_disabled = mddev->recovery_disabled - 1;
5203
5204         conf->raid_disks = mddev->raid_disks;
5205         if (mddev->reshape_position == MaxSector)
5206                 conf->previous_raid_disks = mddev->raid_disks;
5207         else
5208                 conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
5209         max_disks = max(conf->raid_disks, conf->previous_raid_disks);
5210         conf->scribble_len = scribble_len(max_disks);
5211
5212         conf->disks = kzalloc(max_disks * sizeof(struct disk_info),
5213                               GFP_KERNEL);
5214         if (!conf->disks)
5215                 goto abort;
5216
5217         conf->mddev = mddev;
5218
5219         if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
5220                 goto abort;
5221
5222         conf->level = mddev->new_level;
5223         if (raid5_alloc_percpu(conf) != 0)
5224                 goto abort;
5225
5226         pr_debug("raid456: run(%s) called.\n", mdname(mddev));
5227
5228         rdev_for_each(rdev, mddev) {
5229                 raid_disk = rdev->raid_disk;
5230                 if (raid_disk >= max_disks
5231                     || raid_disk < 0)
5232                         continue;
5233                 disk = conf->disks + raid_disk;
5234
5235                 if (test_bit(Replacement, &rdev->flags)) {
5236                         if (disk->replacement)
5237                                 goto abort;
5238                         disk->replacement = rdev;
5239                 } else {
5240                         if (disk->rdev)
5241                                 goto abort;
5242                         disk->rdev = rdev;
5243                 }
5244
5245                 if (test_bit(In_sync, &rdev->flags)) {
5246                         char b[BDEVNAME_SIZE];
5247                         printk(KERN_INFO "md/raid:%s: device %s operational as raid"
5248                                " disk %d\n",
5249                                mdname(mddev), bdevname(rdev->bdev, b), raid_disk);
5250                 } else if (rdev->saved_raid_disk != raid_disk)
5251                         /* Cannot rely on bitmap to complete recovery */
5252                         conf->fullsync = 1;
5253         }
5254
5255         conf->chunk_sectors = mddev->new_chunk_sectors;
5256         conf->level = mddev->new_level;
5257         if (conf->level == 6)
5258                 conf->max_degraded = 2;
5259         else
5260                 conf->max_degraded = 1;
5261         conf->algorithm = mddev->new_layout;
5262         conf->max_nr_stripes = NR_STRIPES;
5263         conf->reshape_progress = mddev->reshape_position;
5264         if (conf->reshape_progress != MaxSector) {
5265                 conf->prev_chunk_sectors = mddev->chunk_sectors;
5266                 conf->prev_algo = mddev->layout;
5267         }
5268
5269         memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
5270                  max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
5271         if (grow_stripes(conf, conf->max_nr_stripes)) {
5272                 printk(KERN_ERR
5273                        "md/raid:%s: couldn't allocate %dkB for buffers\n",
5274                        mdname(mddev), memory);
5275                 goto abort;
5276         } else
5277                 printk(KERN_INFO "md/raid:%s: allocated %dkB\n",
5278                        mdname(mddev), memory);
5279
5280         sprintf(pers_name, "raid%d", mddev->new_level);
5281         conf->thread = md_register_thread(raid5d, mddev, pers_name);
5282         if (!conf->thread) {
5283                 printk(KERN_ERR
5284                        "md/raid:%s: couldn't allocate thread.\n",
5285                        mdname(mddev));
5286                 goto abort;
5287         }
5288
5289         return conf;
5290
5291  abort:
5292         if (conf) {
5293                 free_conf(conf);
5294                 return ERR_PTR(-EIO);
5295         } else
5296                 return ERR_PTR(-ENOMEM);
5297 }
5298
5299
5300 static int only_parity(int raid_disk, int algo, int raid_disks, int max_degraded)
5301 {
5302         switch (algo) {
5303         case ALGORITHM_PARITY_0:
5304                 if (raid_disk < max_degraded)
5305                         return 1;
5306                 break;
5307         case ALGORITHM_PARITY_N:
5308                 if (raid_disk >= raid_disks - max_degraded)
5309                         return 1;
5310                 break;
5311         case ALGORITHM_PARITY_0_6:
5312                 if (raid_disk == 0 ||
5313                     raid_disk == raid_disks - 1)
5314                         return 1;
5315                 break;
5316         case ALGORITHM_LEFT_ASYMMETRIC_6:
5317         case ALGORITHM_RIGHT_ASYMMETRIC_6:
5318         case ALGORITHM_LEFT_SYMMETRIC_6:
5319         case ALGORITHM_RIGHT_SYMMETRIC_6:
5320                 if (raid_disk == raid_disks - 1)
5321                         return 1;
5322         }
5323         return 0;
5324 }
5325
5326 static int run(struct mddev *mddev)
5327 {
5328         struct r5conf *conf;
5329         int working_disks = 0;
5330         int dirty_parity_disks = 0;
5331         struct md_rdev *rdev;
5332         sector_t reshape_offset = 0;
5333         int i;
5334         long long min_offset_diff = 0;
5335         int first = 1;
5336
5337         if (mddev->recovery_cp != MaxSector)
5338                 printk(KERN_NOTICE "md/raid:%s: not clean"
5339                        " -- starting background reconstruction\n",
5340                        mdname(mddev));
5341
5342         rdev_for_each(rdev, mddev) {
5343                 long long diff;
5344                 if (rdev->raid_disk < 0)
5345                         continue;
5346                 diff = (rdev->new_data_offset - rdev->data_offset);
5347                 if (first) {
5348                         min_offset_diff = diff;
5349                         first = 0;
5350                 } else if (mddev->reshape_backwards &&
5351                          diff < min_offset_diff)
5352                         min_offset_diff = diff;
5353                 else if (!mddev->reshape_backwards &&
5354                          diff > min_offset_diff)
5355                         min_offset_diff = diff;
5356         }
5357
5358         if (mddev->reshape_position != MaxSector) {
5359                 /* Check that we can continue the reshape.
5360                  * Difficulties arise if the stripe we would write to
5361                  * next is at or after the stripe we would read from next.
5362                  * For a reshape that changes the number of devices, this
5363                  * is only possible for a very short time, and mdadm makes
5364                  * sure that time appears to have past before assembling
5365                  * the array.  So we fail if that time hasn't passed.
5366                  * For a reshape that keeps the number of devices the same
5367                  * mdadm must be monitoring the reshape can keeping the
5368                  * critical areas read-only and backed up.  It will start
5369                  * the array in read-only mode, so we check for that.
5370                  */
5371                 sector_t here_new, here_old;
5372                 int old_disks;
5373                 int max_degraded = (mddev->level == 6 ? 2 : 1);
5374
5375                 if (mddev->new_level != mddev->level) {
5376                         printk(KERN_ERR "md/raid:%s: unsupported reshape "
5377                                "required - aborting.\n",
5378                                mdname(mddev));
5379                         return -EINVAL;
5380                 }
5381                 old_disks = mddev->raid_disks - mddev->delta_disks;
5382                 /* reshape_position must be on a new-stripe boundary, and one
5383                  * further up in new geometry must map after here in old
5384                  * geometry.
5385                  */
5386                 here_new = mddev->reshape_position;
5387                 if (sector_div(here_new, mddev->new_chunk_sectors *
5388                                (mddev->raid_disks - max_degraded))) {
5389                         printk(KERN_ERR "md/raid:%s: reshape_position not "
5390                                "on a stripe boundary\n", mdname(mddev));
5391                         return -EINVAL;
5392                 }
5393                 reshape_offset = here_new * mddev->new_chunk_sectors;
5394                 /* here_new is the stripe we will write to */
5395                 here_old = mddev->reshape_position;
5396                 sector_div(here_old, mddev->chunk_sectors *
5397                            (old_disks-max_degraded));
5398                 /* here_old is the first stripe that we might need to read
5399                  * from */
5400                 if (mddev->delta_disks == 0) {
5401                         if ((here_new * mddev->new_chunk_sectors !=
5402                              here_old * mddev->chunk_sectors)) {
5403                                 printk(KERN_ERR "md/raid:%s: reshape position is"
5404                                        " confused - aborting\n", mdname(mddev));
5405                                 return -EINVAL;
5406                         }
5407                         /* We cannot be sure it is safe to start an in-place
5408                          * reshape.  It is only safe if user-space is monitoring
5409                          * and taking constant backups.
5410                          * mdadm always starts a situation like this in
5411                          * readonly mode so it can take control before
5412                          * allowing any writes.  So just check for that.
5413                          */
5414                         if (abs(min_offset_diff) >= mddev->chunk_sectors &&
5415                             abs(min_offset_diff) >= mddev->new_chunk_sectors)
5416                                 /* not really in-place - so OK */;
5417                         else if (mddev->ro == 0) {
5418                                 printk(KERN_ERR "md/raid:%s: in-place reshape "
5419                                        "must be started in read-only mode "
5420                                        "- aborting\n",
5421                                        mdname(mddev));
5422                                 return -EINVAL;
5423                         }
5424                 } else if (mddev->reshape_backwards
5425                     ? (here_new * mddev->new_chunk_sectors + min_offset_diff <=
5426                        here_old * mddev->chunk_sectors)
5427                     : (here_new * mddev->new_chunk_sectors >=
5428                        here_old * mddev->chunk_sectors + (-min_offset_diff))) {
5429                         /* Reading from the same stripe as writing to - bad */
5430                         printk(KERN_ERR "md/raid:%s: reshape_position too early for "
5431                                "auto-recovery - aborting.\n",
5432                                mdname(mddev));
5433                         return -EINVAL;
5434                 }
5435                 printk(KERN_INFO "md/raid:%s: reshape will continue\n",
5436                        mdname(mddev));
5437                 /* OK, we should be able to continue; */
5438         } else {
5439                 BUG_ON(mddev->level != mddev->new_level);
5440                 BUG_ON(mddev->layout != mddev->new_layout);
5441                 BUG_ON(mddev->chunk_sectors != mddev->new_chunk_sectors);
5442                 BUG_ON(mddev->delta_disks != 0);
5443         }
5444
5445         if (mddev->private == NULL)
5446                 conf = setup_conf(mddev);
5447         else
5448                 conf = mddev->private;
5449
5450         if (IS_ERR(conf))
5451                 return PTR_ERR(conf);
5452
5453         conf->min_offset_diff = min_offset_diff;
5454         mddev->thread = conf->thread;
5455         conf->thread = NULL;
5456         mddev->private = conf;
5457
5458         for (i = 0; i < conf->raid_disks && conf->previous_raid_disks;
5459              i++) {
5460                 rdev = conf->disks[i].rdev;
5461                 if (!rdev && conf->disks[i].replacement) {
5462                         /* The replacement is all we have yet */
5463                         rdev = conf->disks[i].replacement;
5464                         conf->disks[i].replacement = NULL;
5465                         clear_bit(Replacement, &rdev->flags);
5466                         conf->disks[i].rdev = rdev;
5467                 }
5468                 if (!rdev)
5469                         continue;
5470                 if (conf->disks[i].replacement &&
5471                     conf->reshape_progress != MaxSector) {
5472                         /* replacements and reshape simply do not mix. */
5473                         printk(KERN_ERR "md: cannot handle concurrent "
5474                                "replacement and reshape.\n");
5475                         goto abort;
5476                 }
5477                 if (test_bit(In_sync, &rdev->flags)) {
5478                         working_disks++;
5479                         continue;
5480                 }
5481                 /* This disc is not fully in-sync.  However if it
5482                  * just stored parity (beyond the recovery_offset),
5483                  * when we don't need to be concerned about the
5484                  * array being dirty.
5485                  * When reshape goes 'backwards', we never have
5486                  * partially completed devices, so we only need
5487                  * to worry about reshape going forwards.
5488                  */
5489                 /* Hack because v0.91 doesn't store recovery_offset properly. */
5490                 if (mddev->major_version == 0 &&
5491                     mddev->minor_version > 90)
5492                         rdev->recovery_offset = reshape_offset;
5493
5494                 if (rdev->recovery_offset < reshape_offset) {
5495                         /* We need to check old and new layout */
5496                         if (!only_parity(rdev->raid_disk,
5497                                          conf->algorithm,
5498                                          conf->raid_disks,
5499                                          conf->max_degraded))
5500                                 continue;
5501                 }
5502                 if (!only_parity(rdev->raid_disk,
5503                                  conf->prev_algo,
5504                                  conf->previous_raid_disks,
5505                                  conf->max_degraded))
5506                         continue;
5507                 dirty_parity_disks++;
5508         }
5509
5510         /*
5511          * 0 for a fully functional array, 1 or 2 for a degraded array.
5512          */
5513         mddev->degraded = calc_degraded(conf);
5514
5515         if (has_failed(conf)) {
5516                 printk(KERN_ERR "md/raid:%s: not enough operational devices"
5517                         " (%d/%d failed)\n",
5518                         mdname(mddev), mddev->degraded, conf->raid_disks);
5519                 goto abort;
5520         }
5521
5522         /* device size must be a multiple of chunk size */
5523         mddev->dev_sectors &= ~(mddev->chunk_sectors - 1);
5524         mddev->resync_max_sectors = mddev->dev_sectors;
5525
5526         if (mddev->degraded > dirty_parity_disks &&
5527             mddev->recovery_cp != MaxSector) {
5528                 if (mddev->ok_start_degraded)
5529                         printk(KERN_WARNING
5530                                "md/raid:%s: starting dirty degraded array"
5531                                " - data corruption possible.\n",
5532                                mdname(mddev));
5533                 else {
5534                         printk(KERN_ERR
5535                                "md/raid:%s: cannot start dirty degraded array.\n",
5536                                mdname(mddev));
5537                         goto abort;
5538                 }
5539         }
5540
5541         if (mddev->degraded == 0)
5542                 printk(KERN_INFO "md/raid:%s: raid level %d active with %d out of %d"
5543                        " devices, algorithm %d\n", mdname(mddev), conf->level,
5544                        mddev->raid_disks-mddev->degraded, mddev->raid_disks,
5545                        mddev->new_layout);
5546         else
5547                 printk(KERN_ALERT "md/raid:%s: raid level %d active with %d"
5548                        " out of %d devices, algorithm %d\n",
5549                        mdname(mddev), conf->level,
5550                        mddev->raid_disks - mddev->degraded,
5551                        mddev->raid_disks, mddev->new_layout);
5552
5553         print_raid5_conf(conf);
5554
5555         if (conf->reshape_progress != MaxSector) {
5556                 conf->reshape_safe = conf->reshape_progress;
5557                 atomic_set(&conf->reshape_stripes, 0);
5558                 clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
5559                 clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
5560                 set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
5561                 set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
5562                 mddev->sync_thread = md_register_thread(md_do_sync, mddev,
5563                                                         "reshape");
5564         }
5565
5566
5567         /* Ok, everything is just fine now */
5568         if (mddev->to_remove == &raid5_attrs_group)
5569                 mddev->to_remove = NULL;
5570         else if (mddev->kobj.sd &&
5571             sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
5572                 printk(KERN_WARNING
5573                        "raid5: failed to create sysfs attributes for %s\n",
5574                        mdname(mddev));
5575         md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
5576
5577         if (mddev->queue) {
5578                 int chunk_size;
5579                 bool discard_supported = true;
5580                 /* read-ahead size must cover two whole stripes, which
5581                  * is 2 * (datadisks) * chunksize where 'n' is the
5582                  * number of raid devices
5583                  */
5584                 int data_disks = conf->previous_raid_disks - conf->max_degraded;
5585                 int stripe = data_disks *
5586                         ((mddev->chunk_sectors << 9) / PAGE_SIZE);
5587                 if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
5588                         mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
5589
5590                 blk_queue_merge_bvec(mddev->queue, raid5_mergeable_bvec);
5591
5592                 mddev->queue->backing_dev_info.congested_data = mddev;
5593                 mddev->queue->backing_dev_info.congested_fn = raid5_congested;
5594
5595                 chunk_size = mddev->chunk_sectors << 9;
5596                 blk_queue_io_min(mddev->queue, chunk_size);
5597                 blk_queue_io_opt(mddev->queue, chunk_size *
5598                                  (conf->raid_disks - conf->max_degraded));
5599                 /*
5600                  * We can only discard a whole stripe. It doesn't make sense to
5601                  * discard data disk but write parity disk
5602                  */
5603                 stripe = stripe * PAGE_SIZE;
5604                 /* Round up to power of 2, as discard handling
5605                  * currently assumes that */
5606                 while ((stripe-1) & stripe)
5607                         stripe = (stripe | (stripe-1)) + 1;
5608                 mddev->queue->limits.discard_alignment = stripe;
5609                 mddev->queue->limits.discard_granularity = stripe;
5610                 /*
5611                  * unaligned part of discard request will be ignored, so can't
5612                  * guarantee discard_zerors_data
5613                  */
5614                 mddev->queue->limits.discard_zeroes_data = 0;
5615
5616                 blk_queue_max_write_same_sectors(mddev->queue, 0);
5617
5618                 rdev_for_each(rdev, mddev) {
5619                         disk_stack_limits(mddev->gendisk, rdev->bdev,
5620                                           rdev->data_offset << 9);
5621                         disk_stack_limits(mddev->gendisk, rdev->bdev,
5622                                           rdev->new_data_offset << 9);
5623                         /*
5624                          * discard_zeroes_data is required, otherwise data
5625                          * could be lost. Consider a scenario: discard a stripe
5626                          * (the stripe could be inconsistent if
5627                          * discard_zeroes_data is 0); write one disk of the
5628                          * stripe (the stripe could be inconsistent again
5629                          * depending on which disks are used to calculate
5630                          * parity); the disk is broken; The stripe data of this
5631                          * disk is lost.
5632                          */
5633                         if (!blk_queue_discard(bdev_get_queue(rdev->bdev)) ||
5634                             !bdev_get_queue(rdev->bdev)->
5635                                                 limits.discard_zeroes_data)
5636                                 discard_supported = false;
5637                 }
5638
5639                 if (discard_supported &&
5640                    mddev->queue->limits.max_discard_sectors >= stripe &&
5641                    mddev->queue->limits.discard_granularity >= stripe)
5642                         queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
5643                                                 mddev->queue);
5644                 else
5645                         queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD,
5646                                                 mddev->queue);
5647         }
5648
5649         return 0;
5650 abort:
5651         md_unregister_thread(&mddev->thread);
5652         print_raid5_conf(conf);
5653         free_conf(conf);
5654         mddev->private = NULL;
5655         printk(KERN_ALERT "md/raid:%s: failed to run raid set.\n", mdname(mddev));
5656         return -EIO;
5657 }
5658
5659 static int stop(struct mddev *mddev)
5660 {
5661         struct r5conf *conf = mddev->private;
5662
5663         md_unregister_thread(&mddev->thread);
5664         if (mddev->queue)
5665                 mddev->queue->backing_dev_info.congested_fn = NULL;
5666         free_conf(conf);
5667         mddev->private = NULL;
5668         mddev->to_remove = &raid5_attrs_group;
5669         return 0;
5670 }
5671
5672 static void status(struct seq_file *seq, struct mddev *mddev)
5673 {
5674         struct r5conf *conf = mddev->private;
5675         int i;
5676
5677         seq_printf(seq, " level %d, %dk chunk, algorithm %d", mddev->level,
5678                 mddev->chunk_sectors / 2, mddev->layout);
5679         seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded);
5680         for (i = 0; i < conf->raid_disks; i++)
5681                 seq_printf (seq, "%s",
5682                                conf->disks[i].rdev &&
5683                                test_bit(In_sync, &conf->disks[i].rdev->flags) ? "U" : "_");
5684         seq_printf (seq, "]");
5685 }
5686
5687 static void print_raid5_conf (struct r5conf *conf)
5688 {
5689         int i;
5690         struct disk_info *tmp;
5691
5692         printk(KERN_DEBUG "RAID conf printout:\n");
5693         if (!conf) {
5694                 printk("(conf==NULL)\n");
5695                 return;
5696         }
5697         printk(KERN_DEBUG " --- level:%d rd:%d wd:%d\n", conf->level,
5698                conf->raid_disks,
5699                conf->raid_disks - conf->mddev->degraded);
5700
5701         for (i = 0; i < conf->raid_disks; i++) {
5702                 char b[BDEVNAME_SIZE];
5703                 tmp = conf->disks + i;
5704                 if (tmp->rdev)
5705                         printk(KERN_DEBUG " disk %d, o:%d, dev:%s\n",
5706                                i, !test_bit(Faulty, &tmp->rdev->flags),
5707                                bdevname(tmp->rdev->bdev, b));
5708         }
5709 }
5710
5711 static int raid5_spare_active(struct mddev *mddev)
5712 {
5713         int i;
5714         struct r5conf *conf = mddev->private;
5715         struct disk_info *tmp;
5716         int count = 0;
5717         unsigned long flags;
5718
5719         for (i = 0; i < conf->raid_disks; i++) {
5720                 tmp = conf->disks + i;
5721                 if (tmp->replacement
5722                     && tmp->replacement->recovery_offset == MaxSector
5723                     && !test_bit(Faulty, &tmp->replacement->flags)
5724                     && !test_and_set_bit(In_sync, &tmp->replacement->flags)) {
5725                         /* Replacement has just become active. */
5726                         if (!tmp->rdev
5727                             || !test_and_clear_bit(In_sync, &tmp->rdev->flags))
5728                                 count++;
5729                         if (tmp->rdev) {
5730                                 /* Replaced device not technically faulty,
5731                                  * but we need to be sure it gets removed
5732                                  * and never re-added.
5733                                  */
5734                                 set_bit(Faulty, &tmp->rdev->flags);
5735                                 sysfs_notify_dirent_safe(
5736                                         tmp->rdev->sysfs_state);
5737                         }
5738                         sysfs_notify_dirent_safe(tmp->replacement->sysfs_state);
5739                 } else if (tmp->rdev
5740                     && tmp->rdev->recovery_offset == MaxSector
5741                     && !test_bit(Faulty, &tmp->rdev->flags)
5742                     && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
5743                         count++;
5744                         sysfs_notify_dirent_safe(tmp->rdev->sysfs_state);
5745                 }
5746         }
5747         spin_lock_irqsave(&conf->device_lock, flags);
5748         mddev->degraded = calc_degraded(conf);
5749         spin_unlock_irqrestore(&conf->device_lock, flags);
5750         print_raid5_conf(conf);
5751         return count;
5752 }
5753
5754 static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
5755 {
5756         struct r5conf *conf = mddev->private;
5757         int err = 0;
5758         int number = rdev->raid_disk;
5759         struct md_rdev **rdevp;
5760         struct disk_info *p = conf->disks + number;
5761
5762         print_raid5_conf(conf);
5763         if (rdev == p->rdev)
5764                 rdevp = &p->rdev;
5765         else if (rdev == p->replacement)
5766                 rdevp = &p->replacement;
5767         else
5768                 return 0;
5769
5770         if (number >= conf->raid_disks &&
5771             conf->reshape_progress == MaxSector)
5772                 clear_bit(In_sync, &rdev->flags);
5773
5774         if (test_bit(In_sync, &rdev->flags) ||
5775             atomic_read(&rdev->nr_pending)) {
5776                 err = -EBUSY;
5777                 goto abort;
5778         }
5779         /* Only remove non-faulty devices if recovery
5780          * isn't possible.
5781          */
5782         if (!test_bit(Faulty, &rdev->flags) &&
5783             mddev->recovery_disabled != conf->recovery_disabled &&
5784             !has_failed(conf) &&
5785             (!p->replacement || p->replacement == rdev) &&
5786             number < conf->raid_disks) {
5787                 err = -EBUSY;
5788                 goto abort;
5789         }
5790         *rdevp = NULL;
5791         synchronize_rcu();
5792         if (atomic_read(&rdev->nr_pending)) {
5793                 /* lost the race, try later */
5794                 err = -EBUSY;
5795                 *rdevp = rdev;
5796         } else if (p->replacement) {
5797                 /* We must have just cleared 'rdev' */
5798                 p->rdev = p->replacement;
5799                 clear_bit(Replacement, &p->replacement->flags);
5800                 smp_mb(); /* Make sure other CPUs may see both as identical
5801                            * but will never see neither - if they are careful
5802                            */
5803                 p->replacement = NULL;
5804                 clear_bit(WantReplacement, &rdev->flags);
5805         } else
5806                 /* We might have just removed the Replacement as faulty-
5807                  * clear the bit just in case
5808                  */
5809                 clear_bit(WantReplacement, &rdev->flags);
5810 abort:
5811
5812         print_raid5_conf(conf);
5813         return err;
5814 }
5815
5816 static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
5817 {
5818         struct r5conf *conf = mddev->private;
5819         int err = -EEXIST;
5820         int disk;
5821         struct disk_info *p;
5822         int first = 0;
5823         int last = conf->raid_disks - 1;
5824
5825         if (mddev->recovery_disabled == conf->recovery_disabled)
5826                 return -EBUSY;
5827
5828         if (rdev->saved_raid_disk < 0 && has_failed(conf))
5829                 /* no point adding a device */
5830                 return -EINVAL;
5831
5832         if (rdev->raid_disk >= 0)
5833                 first = last = rdev->raid_disk;
5834
5835         /*
5836          * find the disk ... but prefer rdev->saved_raid_disk
5837          * if possible.
5838          */
5839         if (rdev->saved_raid_disk >= 0 &&
5840             rdev->saved_raid_disk >= first &&
5841             conf->disks[rdev->saved_raid_disk].rdev == NULL)
5842                 first = rdev->saved_raid_disk;
5843
5844         for (disk = first; disk <= last; disk++) {
5845                 p = conf->disks + disk;
5846                 if (p->rdev == NULL) {
5847                         clear_bit(In_sync, &rdev->flags);
5848                         rdev->raid_disk = disk;
5849                         err = 0;
5850                         if (rdev->saved_raid_disk != disk)
5851                                 conf->fullsync = 1;
5852                         rcu_assign_pointer(p->rdev, rdev);
5853                         goto out;
5854                 }
5855         }
5856         for (disk = first; disk <= last; disk++) {
5857                 p = conf->disks + disk;
5858                 if (test_bit(WantReplacement, &p->rdev->flags) &&
5859                     p->replacement == NULL) {
5860                         clear_bit(In_sync, &rdev->flags);
5861                         set_bit(Replacement, &rdev->flags);
5862                         rdev->raid_disk = disk;
5863                         err = 0;
5864                         conf->fullsync = 1;
5865                         rcu_assign_pointer(p->replacement, rdev);
5866                         break;
5867                 }
5868         }
5869 out:
5870         print_raid5_conf(conf);
5871         return err;
5872 }
5873
5874 static int raid5_resize(struct mddev *mddev, sector_t sectors)
5875 {
5876         /* no resync is happening, and there is enough space
5877          * on all devices, so we can resize.
5878          * We need to make sure resync covers any new space.
5879          * If the array is shrinking we should possibly wait until
5880          * any io in the removed space completes, but it hardly seems
5881          * worth it.
5882          */
5883         sector_t newsize;
5884         sectors &= ~((sector_t)mddev->chunk_sectors - 1);
5885         newsize = raid5_size(mddev, sectors, mddev->raid_disks);
5886         if (mddev->external_size &&
5887             mddev->array_sectors > newsize)
5888                 return -EINVAL;
5889         if (mddev->bitmap) {
5890                 int ret = bitmap_resize(mddev->bitmap, sectors, 0, 0);
5891                 if (ret)
5892                         return ret;
5893         }
5894         md_set_array_sectors(mddev, newsize);
5895         set_capacity(mddev->gendisk, mddev->array_sectors);
5896         revalidate_disk(mddev->gendisk);
5897         if (sectors > mddev->dev_sectors &&
5898             mddev->recovery_cp > mddev->dev_sectors) {
5899                 mddev->recovery_cp = mddev->dev_sectors;
5900                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
5901         }
5902         mddev->dev_sectors = sectors;
5903         mddev->resync_max_sectors = sectors;
5904         return 0;
5905 }
5906
5907 static int check_stripe_cache(struct mddev *mddev)
5908 {
5909         /* Can only proceed if there are plenty of stripe_heads.
5910          * We need a minimum of one full stripe,, and for sensible progress
5911          * it is best to have about 4 times that.
5912          * If we require 4 times, then the default 256 4K stripe_heads will
5913          * allow for chunk sizes up to 256K, which is probably OK.
5914          * If the chunk size is greater, user-space should request more
5915          * stripe_heads first.
5916          */
5917         struct r5conf *conf = mddev->private;
5918         if (((mddev->chunk_sectors << 9) / STRIPE_SIZE) * 4
5919             > conf->max_nr_stripes ||
5920             ((mddev->new_chunk_sectors << 9) / STRIPE_SIZE) * 4
5921             > conf->max_nr_stripes) {
5922                 printk(KERN_WARNING "md/raid:%s: reshape: not enough stripes.  Needed %lu\n",
5923                        mdname(mddev),
5924                        ((max(mddev->chunk_sectors, mddev->new_chunk_sectors) << 9)
5925                         / STRIPE_SIZE)*4);
5926                 return 0;
5927         }
5928         return 1;
5929 }
5930
5931 static int check_reshape(struct mddev *mddev)
5932 {
5933         struct r5conf *conf = mddev->private;
5934
5935         if (mddev->delta_disks == 0 &&
5936             mddev->new_layout == mddev->layout &&
5937             mddev->new_chunk_sectors == mddev->chunk_sectors)
5938                 return 0; /* nothing to do */
5939         if (has_failed(conf))
5940                 return -EINVAL;
5941         if (mddev->delta_disks < 0) {
5942                 /* We might be able to shrink, but the devices must
5943                  * be made bigger first.
5944                  * For raid6, 4 is the minimum size.
5945                  * Otherwise 2 is the minimum
5946                  */
5947                 int min = 2;
5948                 if (mddev->level == 6)
5949                         min = 4;
5950                 if (mddev->raid_disks + mddev->delta_disks < min)
5951                         return -EINVAL;
5952         }
5953
5954         if (!check_stripe_cache(mddev))
5955                 return -ENOSPC;
5956
5957         return resize_stripes(conf, (conf->previous_raid_disks
5958                                      + mddev->delta_disks));
5959 }
5960
5961 static int raid5_start_reshape(struct mddev *mddev)
5962 {
5963         struct r5conf *conf = mddev->private;
5964         struct md_rdev *rdev;
5965         int spares = 0;
5966         unsigned long flags;
5967
5968         if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
5969                 return -EBUSY;
5970
5971         if (!check_stripe_cache(mddev))
5972                 return -ENOSPC;
5973
5974         if (has_failed(conf))
5975                 return -EINVAL;
5976
5977         rdev_for_each(rdev, mddev) {
5978                 if (!test_bit(In_sync, &rdev->flags)
5979                     && !test_bit(Faulty, &rdev->flags))
5980                         spares++;
5981         }
5982
5983         if (spares - mddev->degraded < mddev->delta_disks - conf->max_degraded)
5984                 /* Not enough devices even to make a degraded array
5985                  * of that size
5986                  */
5987                 return -EINVAL;
5988
5989         /* Refuse to reduce size of the array.  Any reductions in
5990          * array size must be through explicit setting of array_size
5991          * attribute.
5992          */
5993         if (raid5_size(mddev, 0, conf->raid_disks + mddev->delta_disks)
5994             < mddev->array_sectors) {
5995                 printk(KERN_ERR "md/raid:%s: array size must be reduced "
5996                        "before number of disks\n", mdname(mddev));
5997                 return -EINVAL;
5998         }
5999
6000         atomic_set(&conf->reshape_stripes, 0);
6001         spin_lock_irq(&conf->device_lock);
6002         conf->previous_raid_disks = conf->raid_disks;
6003         conf->raid_disks += mddev->delta_disks;
6004         conf->prev_chunk_sectors = conf->chunk_sectors;
6005         conf->chunk_sectors = mddev->new_chunk_sectors;
6006         conf->prev_algo = conf->algorithm;
6007         conf->algorithm = mddev->new_layout;
6008         conf->generation++;
6009         /* Code that selects data_offset needs to see the generation update
6010          * if reshape_progress has been set - so a memory barrier needed.
6011          */
6012         smp_mb();
6013         if (mddev->reshape_backwards)
6014                 conf->reshape_progress = raid5_size(mddev, 0, 0);
6015         else
6016                 conf->reshape_progress = 0;
6017         conf->reshape_safe = conf->reshape_progress;
6018         spin_unlock_irq(&conf->device_lock);
6019
6020         /* Add some new drives, as many as will fit.
6021          * We know there are enough to make the newly sized array work.
6022          * Don't add devices if we are reducing the number of
6023          * devices in the array.  This is because it is not possible
6024          * to correctly record the "partially reconstructed" state of
6025          * such devices during the reshape and confusion could result.
6026          */
6027         if (mddev->delta_disks >= 0) {
6028                 rdev_for_each(rdev, mddev)
6029                         if (rdev->raid_disk < 0 &&
6030                             !test_bit(Faulty, &rdev->flags)) {
6031                                 if (raid5_add_disk(mddev, rdev) == 0) {
6032                                         if (rdev->raid_disk
6033                                             >= conf->previous_raid_disks)
6034                                                 set_bit(In_sync, &rdev->flags);
6035                                         else
6036                                                 rdev->recovery_offset = 0;
6037
6038                                         if (sysfs_link_rdev(mddev, rdev))
6039                                                 /* Failure here is OK */;
6040                                 }
6041                         } else if (rdev->raid_disk >= conf->previous_raid_disks
6042                                    && !test_bit(Faulty, &rdev->flags)) {
6043                                 /* This is a spare that was manually added */
6044                                 set_bit(In_sync, &rdev->flags);
6045                         }
6046
6047                 /* When a reshape changes the number of devices,
6048                  * ->degraded is measured against the larger of the
6049                  * pre and post number of devices.
6050                  */
6051                 spin_lock_irqsave(&conf->device_lock, flags);
6052                 mddev->degraded = calc_degraded(conf);
6053                 spin_unlock_irqrestore(&conf->device_lock, flags);
6054         }
6055         mddev->raid_disks = conf->raid_disks;
6056         mddev->reshape_position = conf->reshape_progress;
6057         set_bit(MD_CHANGE_DEVS, &mddev->flags);
6058
6059         clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
6060         clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
6061         set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
6062         set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
6063         mddev->sync_thread = md_register_thread(md_do_sync, mddev,
6064                                                 "reshape");
6065         if (!mddev->sync_thread) {
6066                 mddev->recovery = 0;
6067                 spin_lock_irq(&conf->device_lock);
6068                 mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
6069                 rdev_for_each(rdev, mddev)
6070                         rdev->new_data_offset = rdev->data_offset;
6071                 smp_wmb();
6072                 conf->reshape_progress = MaxSector;
6073                 mddev->reshape_position = MaxSector;
6074                 spin_unlock_irq(&conf->device_lock);
6075                 return -EAGAIN;
6076         }
6077         conf->reshape_checkpoint = jiffies;
6078         md_wakeup_thread(mddev->sync_thread);
6079         md_new_event(mddev);
6080         return 0;
6081 }
6082
6083 /* This is called from the reshape thread and should make any
6084  * changes needed in 'conf'
6085  */
6086 static void end_reshape(struct r5conf *conf)
6087 {
6088
6089         if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
6090                 struct md_rdev *rdev;
6091
6092                 spin_lock_irq(&conf->device_lock);
6093                 conf->previous_raid_disks = conf->raid_disks;
6094                 rdev_for_each(rdev, conf->mddev)
6095                         rdev->data_offset = rdev->new_data_offset;
6096                 smp_wmb();
6097                 conf->reshape_progress = MaxSector;
6098                 spin_unlock_irq(&conf->device_lock);
6099                 wake_up(&conf->wait_for_overlap);
6100
6101                 /* read-ahead size must cover two whole stripes, which is
6102                  * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
6103                  */
6104                 if (conf->mddev->queue) {
6105                         int data_disks = conf->raid_disks - conf->max_degraded;
6106                         int stripe = data_disks * ((conf->chunk_sectors << 9)
6107                                                    / PAGE_SIZE);
6108                         if (conf->mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
6109                                 conf->mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
6110                 }
6111         }
6112 }
6113
6114 /* This is called from the raid5d thread with mddev_lock held.
6115  * It makes config changes to the device.
6116  */
6117 static void raid5_finish_reshape(struct mddev *mddev)
6118 {
6119         struct r5conf *conf = mddev->private;
6120
6121         if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
6122
6123                 if (mddev->delta_disks > 0) {
6124                         md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
6125                         set_capacity(mddev->gendisk, mddev->array_sectors);
6126                         revalidate_disk(mddev->gendisk);
6127                 } else {
6128                         int d;
6129                         spin_lock_irq(&conf->device_lock);
6130                         mddev->degraded = calc_degraded(conf);
6131                         spin_unlock_irq(&conf->device_lock);
6132                         for (d = conf->raid_disks ;
6133                              d < conf->raid_disks - mddev->delta_disks;
6134                              d++) {
6135                                 struct md_rdev *rdev = conf->disks[d].rdev;
6136                                 if (rdev)
6137                                         clear_bit(In_sync, &rdev->flags);
6138                                 rdev = conf->disks[d].replacement;
6139                                 if (rdev)
6140                                         clear_bit(In_sync, &rdev->flags);
6141                         }
6142                 }
6143                 mddev->layout = conf->algorithm;
6144                 mddev->chunk_sectors = conf->chunk_sectors;
6145                 mddev->reshape_position = MaxSector;
6146                 mddev->delta_disks = 0;
6147                 mddev->reshape_backwards = 0;
6148         }
6149 }
6150
6151 static void raid5_quiesce(struct mddev *mddev, int state)
6152 {
6153         struct r5conf *conf = mddev->private;
6154
6155         switch(state) {
6156         case 2: /* resume for a suspend */
6157                 wake_up(&conf->wait_for_overlap);
6158                 break;
6159
6160         case 1: /* stop all writes */
6161                 spin_lock_irq(&conf->device_lock);
6162                 /* '2' tells resync/reshape to pause so that all
6163                  * active stripes can drain
6164                  */
6165                 conf->quiesce = 2;
6166                 wait_event_lock_irq(conf->wait_for_stripe,
6167                                     atomic_read(&conf->active_stripes) == 0 &&
6168                                     atomic_read(&conf->active_aligned_reads) == 0,
6169                                     conf->device_lock);
6170                 conf->quiesce = 1;
6171                 spin_unlock_irq(&conf->device_lock);
6172                 /* allow reshape to continue */
6173                 wake_up(&conf->wait_for_overlap);
6174                 break;
6175
6176         case 0: /* re-enable writes */
6177                 spin_lock_irq(&conf->device_lock);
6178                 conf->quiesce = 0;
6179                 wake_up(&conf->wait_for_stripe);
6180                 wake_up(&conf->wait_for_overlap);
6181                 spin_unlock_irq(&conf->device_lock);
6182                 break;
6183         }
6184 }
6185
6186
6187 static void *raid45_takeover_raid0(struct mddev *mddev, int level)
6188 {
6189         struct r0conf *raid0_conf = mddev->private;
6190         sector_t sectors;
6191
6192         /* for raid0 takeover only one zone is supported */
6193         if (raid0_conf->nr_strip_zones > 1) {
6194                 printk(KERN_ERR "md/raid:%s: cannot takeover raid0 with more than one zone.\n",
6195                        mdname(mddev));
6196                 return ERR_PTR(-EINVAL);
6197         }
6198
6199         sectors = raid0_conf->strip_zone[0].zone_end;
6200         sector_div(sectors, raid0_conf->strip_zone[0].nb_dev);
6201         mddev->dev_sectors = sectors;
6202         mddev->new_level = level;
6203         mddev->new_layout = ALGORITHM_PARITY_N;
6204         mddev->new_chunk_sectors = mddev->chunk_sectors;
6205         mddev->raid_disks += 1;
6206         mddev->delta_disks = 1;
6207         /* make sure it will be not marked as dirty */
6208         mddev->recovery_cp = MaxSector;
6209
6210         return setup_conf(mddev);
6211 }
6212
6213
6214 static void *raid5_takeover_raid1(struct mddev *mddev)
6215 {
6216         int chunksect;
6217
6218         if (mddev->raid_disks != 2 ||
6219             mddev->degraded > 1)
6220                 return ERR_PTR(-EINVAL);
6221
6222         /* Should check if there are write-behind devices? */
6223
6224         chunksect = 64*2; /* 64K by default */
6225
6226         /* The array must be an exact multiple of chunksize */
6227         while (chunksect && (mddev->array_sectors & (chunksect-1)))
6228                 chunksect >>= 1;
6229
6230         if ((chunksect<<9) < STRIPE_SIZE)
6231                 /* array size does not allow a suitable chunk size */
6232                 return ERR_PTR(-EINVAL);
6233
6234         mddev->new_level = 5;
6235         mddev->new_layout = ALGORITHM_LEFT_SYMMETRIC;
6236         mddev->new_chunk_sectors = chunksect;
6237
6238         return setup_conf(mddev);
6239 }
6240
6241 static void *raid5_takeover_raid6(struct mddev *mddev)
6242 {
6243         int new_layout;
6244
6245         switch (mddev->layout) {
6246         case ALGORITHM_LEFT_ASYMMETRIC_6:
6247                 new_layout = ALGORITHM_LEFT_ASYMMETRIC;
6248                 break;
6249         case ALGORITHM_RIGHT_ASYMMETRIC_6:
6250                 new_layout = ALGORITHM_RIGHT_ASYMMETRIC;
6251                 break;
6252         case ALGORITHM_LEFT_SYMMETRIC_6:
6253                 new_layout = ALGORITHM_LEFT_SYMMETRIC;
6254                 break;
6255         case ALGORITHM_RIGHT_SYMMETRIC_6:
6256                 new_layout = ALGORITHM_RIGHT_SYMMETRIC;
6257                 break;
6258         case ALGORITHM_PARITY_0_6:
6259                 new_layout = ALGORITHM_PARITY_0;
6260                 break;
6261         case ALGORITHM_PARITY_N:
6262                 new_layout = ALGORITHM_PARITY_N;
6263                 break;
6264         default:
6265                 return ERR_PTR(-EINVAL);
6266         }
6267         mddev->new_level = 5;
6268         mddev->new_layout = new_layout;
6269         mddev->delta_disks = -1;
6270         mddev->raid_disks -= 1;
6271         return setup_conf(mddev);
6272 }
6273
6274
6275 static int raid5_check_reshape(struct mddev *mddev)
6276 {
6277         /* For a 2-drive array, the layout and chunk size can be changed
6278          * immediately as not restriping is needed.
6279          * For larger arrays we record the new value - after validation
6280          * to be used by a reshape pass.
6281          */
6282         struct r5conf *conf = mddev->private;
6283         int new_chunk = mddev->new_chunk_sectors;
6284
6285         if (mddev->new_layout >= 0 && !algorithm_valid_raid5(mddev->new_layout))
6286                 return -EINVAL;
6287         if (new_chunk > 0) {
6288                 if (!is_power_of_2(new_chunk))
6289                         return -EINVAL;
6290                 if (new_chunk < (PAGE_SIZE>>9))
6291                         return -EINVAL;
6292                 if (mddev->array_sectors & (new_chunk-1))
6293                         /* not factor of array size */
6294                         return -EINVAL;
6295         }
6296
6297         /* They look valid */
6298
6299         if (mddev->raid_disks == 2) {
6300                 /* can make the change immediately */
6301                 if (mddev->new_layout >= 0) {
6302                         conf->algorithm = mddev->new_layout;
6303                         mddev->layout = mddev->new_layout;
6304                 }
6305                 if (new_chunk > 0) {
6306                         conf->chunk_sectors = new_chunk ;
6307                         mddev->chunk_sectors = new_chunk;
6308                 }
6309                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
6310                 md_wakeup_thread(mddev->thread);
6311         }
6312         return check_reshape(mddev);
6313 }
6314
6315 static int raid6_check_reshape(struct mddev *mddev)
6316 {
6317         int new_chunk = mddev->new_chunk_sectors;
6318
6319         if (mddev->new_layout >= 0 && !algorithm_valid_raid6(mddev->new_layout))
6320                 return -EINVAL;
6321         if (new_chunk > 0) {
6322                 if (!is_power_of_2(new_chunk))
6323                         return -EINVAL;
6324                 if (new_chunk < (PAGE_SIZE >> 9))
6325                         return -EINVAL;
6326                 if (mddev->array_sectors & (new_chunk-1))
6327                         /* not factor of array size */
6328                         return -EINVAL;
6329         }
6330
6331         /* They look valid */
6332         return check_reshape(mddev);
6333 }
6334
6335 static void *raid5_takeover(struct mddev *mddev)
6336 {
6337         /* raid5 can take over:
6338          *  raid0 - if there is only one strip zone - make it a raid4 layout
6339          *  raid1 - if there are two drives.  We need to know the chunk size
6340          *  raid4 - trivial - just use a raid4 layout.
6341          *  raid6 - Providing it is a *_6 layout
6342          */
6343         if (mddev->level == 0)
6344                 return raid45_takeover_raid0(mddev, 5);
6345         if (mddev->level == 1)
6346                 return raid5_takeover_raid1(mddev);
6347         if (mddev->level == 4) {
6348                 mddev->new_layout = ALGORITHM_PARITY_N;
6349                 mddev->new_level = 5;
6350                 return setup_conf(mddev);
6351         }
6352         if (mddev->level == 6)
6353                 return raid5_takeover_raid6(mddev);
6354
6355         return ERR_PTR(-EINVAL);
6356 }
6357
6358 static void *raid4_takeover(struct mddev *mddev)
6359 {
6360         /* raid4 can take over:
6361          *  raid0 - if there is only one strip zone
6362          *  raid5 - if layout is right
6363          */
6364         if (mddev->level == 0)
6365                 return raid45_takeover_raid0(mddev, 4);
6366         if (mddev->level == 5 &&
6367             mddev->layout == ALGORITHM_PARITY_N) {
6368                 mddev->new_layout = 0;
6369                 mddev->new_level = 4;
6370                 return setup_conf(mddev);
6371         }
6372         return ERR_PTR(-EINVAL);
6373 }
6374
6375 static struct md_personality raid5_personality;
6376
6377 static void *raid6_takeover(struct mddev *mddev)
6378 {
6379         /* Currently can only take over a raid5.  We map the
6380          * personality to an equivalent raid6 personality
6381          * with the Q block at the end.
6382          */
6383         int new_layout;
6384
6385         if (mddev->pers != &raid5_personality)
6386                 return ERR_PTR(-EINVAL);
6387         if (mddev->degraded > 1)
6388                 return ERR_PTR(-EINVAL);
6389         if (mddev->raid_disks > 253)
6390                 return ERR_PTR(-EINVAL);
6391         if (mddev->raid_disks < 3)
6392                 return ERR_PTR(-EINVAL);
6393
6394         switch (mddev->layout) {
6395         case ALGORITHM_LEFT_ASYMMETRIC:
6396                 new_layout = ALGORITHM_LEFT_ASYMMETRIC_6;
6397                 break;
6398         case ALGORITHM_RIGHT_ASYMMETRIC:
6399                 new_layout = ALGORITHM_RIGHT_ASYMMETRIC_6;
6400                 break;
6401         case ALGORITHM_LEFT_SYMMETRIC:
6402                 new_layout = ALGORITHM_LEFT_SYMMETRIC_6;
6403                 break;
6404         case ALGORITHM_RIGHT_SYMMETRIC:
6405                 new_layout = ALGORITHM_RIGHT_SYMMETRIC_6;
6406                 break;
6407         case ALGORITHM_PARITY_0:
6408                 new_layout = ALGORITHM_PARITY_0_6;
6409                 break;
6410         case ALGORITHM_PARITY_N:
6411                 new_layout = ALGORITHM_PARITY_N;
6412                 break;
6413         default:
6414                 return ERR_PTR(-EINVAL);
6415         }
6416         mddev->new_level = 6;
6417         mddev->new_layout = new_layout;
6418         mddev->delta_disks = 1;
6419         mddev->raid_disks += 1;
6420         return setup_conf(mddev);
6421 }
6422
6423
6424 static struct md_personality raid6_personality =
6425 {
6426         .name           = "raid6",
6427         .level          = 6,
6428         .owner          = THIS_MODULE,
6429         .make_request   = make_request,
6430         .run            = run,
6431         .stop           = stop,
6432         .status         = status,
6433         .error_handler  = error,
6434         .hot_add_disk   = raid5_add_disk,
6435         .hot_remove_disk= raid5_remove_disk,
6436         .spare_active   = raid5_spare_active,
6437         .sync_request   = sync_request,
6438         .resize         = raid5_resize,
6439         .size           = raid5_size,
6440         .check_reshape  = raid6_check_reshape,
6441         .start_reshape  = raid5_start_reshape,
6442         .finish_reshape = raid5_finish_reshape,
6443         .quiesce        = raid5_quiesce,
6444         .takeover       = raid6_takeover,
6445 };
6446 static struct md_personality raid5_personality =
6447 {
6448         .name           = "raid5",
6449         .level          = 5,
6450         .owner          = THIS_MODULE,
6451         .make_request   = make_request,
6452         .run            = run,
6453         .stop           = stop,
6454         .status         = status,
6455         .error_handler  = error,
6456         .hot_add_disk   = raid5_add_disk,
6457         .hot_remove_disk= raid5_remove_disk,
6458         .spare_active   = raid5_spare_active,
6459         .sync_request   = sync_request,
6460         .resize         = raid5_resize,
6461         .size           = raid5_size,
6462         .check_reshape  = raid5_check_reshape,
6463         .start_reshape  = raid5_start_reshape,
6464         .finish_reshape = raid5_finish_reshape,
6465         .quiesce        = raid5_quiesce,
6466         .takeover       = raid5_takeover,
6467 };
6468
6469 static struct md_personality raid4_personality =
6470 {
6471         .name           = "raid4",
6472         .level          = 4,
6473         .owner          = THIS_MODULE,
6474         .make_request   = make_request,
6475         .run            = run,
6476         .stop           = stop,
6477         .status         = status,
6478         .error_handler  = error,
6479         .hot_add_disk   = raid5_add_disk,
6480         .hot_remove_disk= raid5_remove_disk,
6481         .spare_active   = raid5_spare_active,
6482         .sync_request   = sync_request,
6483         .resize         = raid5_resize,
6484         .size           = raid5_size,
6485         .check_reshape  = raid5_check_reshape,
6486         .start_reshape  = raid5_start_reshape,
6487         .finish_reshape = raid5_finish_reshape,
6488         .quiesce        = raid5_quiesce,
6489         .takeover       = raid4_takeover,
6490 };
6491
6492 static int __init raid5_init(void)
6493 {
6494         register_md_personality(&raid6_personality);
6495         register_md_personality(&raid5_personality);
6496         register_md_personality(&raid4_personality);
6497         return 0;
6498 }
6499
6500 static void raid5_exit(void)
6501 {
6502         unregister_md_personality(&raid6_personality);
6503         unregister_md_personality(&raid5_personality);
6504         unregister_md_personality(&raid4_personality);
6505 }
6506
6507 module_init(raid5_init);
6508 module_exit(raid5_exit);
6509 MODULE_LICENSE("GPL");
6510 MODULE_DESCRIPTION("RAID4/5/6 (striping with parity) personality for MD");
6511 MODULE_ALIAS("md-personality-4"); /* RAID5 */
6512 MODULE_ALIAS("md-raid5");
6513 MODULE_ALIAS("md-raid4");
6514 MODULE_ALIAS("md-level-5");
6515 MODULE_ALIAS("md-level-4");
6516 MODULE_ALIAS("md-personality-8"); /* RAID6 */
6517 MODULE_ALIAS("md-raid6");
6518 MODULE_ALIAS("md-level-6");
6519
6520 /* This used to be two separate modules, they were: */
6521 MODULE_ALIAS("raid5");
6522 MODULE_ALIAS("raid6");