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 static bool devices_handle_discard_safely = false;
  64 module_param(devices_handle_discard_safely, bool, 0644);
  65 MODULE_PARM_DESC(devices_handle_discard_safely,
  66                  "Set to Y if all devices in each array reliably return zeroes on reads from discarded regions");
  67 /*
  68  * Stripe cache
  69  */
  70
  71 #define NR_STRIPES              256
  72 #define STRIPE_SIZE             PAGE_SIZE
  73 #define STRIPE_SHIFT            (PAGE_SHIFT - 9)
  74 #define STRIPE_SECTORS          (STRIPE_SIZE>>9)
  75 #define IO_THRESHOLD            1
  76 #define BYPASS_THRESHOLD        1
  77 #define NR_HASH                 (PAGE_SIZE / sizeof(struct hlist_head))
  78 #define HASH_MASK               (NR_HASH - 1)
  79
  80 static inline struct hlist_head *stripe_hash(struct r5conf *conf, sector_t sect)
  81 {
  82         int hash = (sect >> STRIPE_SHIFT) & HASH_MASK;
  83         return &conf->stripe_hashtbl[hash];
  84 }
  85
  86 /* bio's attached to a stripe+device for I/O are linked together in bi_sector
  87  * order without overlap.  There may be several bio's per stripe+device, and
  88  * a bio could span several devices.
  89  * When walking this list for a particular stripe+device, we must never proceed
  90  * beyond a bio that extends past this device, as the next bio might no longer
  91  * be valid.
  92  * This function is used to determine the 'next' bio in the list, given the sector
  93  * of the current stripe+device
  94  */
  95 static inline struct bio *r5_next_bio(struct bio *bio, sector_t sector)
  96 {
  97         int sectors = bio_sectors(bio);
  98         if (bio->bi_sector + sectors < sector + STRIPE_SECTORS)
  99                 return bio->bi_next;
 100         else
 101                 return NULL;
 102 }
 103
 104 /*
 105  * We maintain a biased count of active stripes in the bottom 16 bits of
 106  * bi_phys_segments, and a count of processed stripes in the upper 16 bits
 107  */
 108 static inline int raid5_bi_processed_stripes(struct bio *bio)
 109 {
 110         atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 111         return (atomic_read(segments) >> 16) & 0xffff;
 112 }
 113
 114 static inline int raid5_dec_bi_active_stripes(struct bio *bio)
 115 {
 116         atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 117         return atomic_sub_return(1, segments) & 0xffff;
 118 }
 119
 120 static inline void raid5_inc_bi_active_stripes(struct bio *bio)
 121 {
 122         atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 123         atomic_inc(segments);
 124 }
 125
 126 static inline void raid5_set_bi_processed_stripes(struct bio *bio,
 127         unsigned int cnt)
 128 {
 129         atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 130         int old, new;
 131
 132         do {
 133                 old = atomic_read(segments);
 134                 new = (old & 0xffff) | (cnt << 16);
 135         } while (atomic_cmpxchg(segments, old, new) != old);
 136 }
 137
 138 static inline void raid5_set_bi_stripes(struct bio *bio, unsigned int cnt)
 139 {
 140         atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 141         atomic_set(segments, cnt);
 142 }
 143
 144 /* Find first data disk in a raid6 stripe */
 145 static inline int raid6_d0(struct stripe_head *sh)
 146 {
 147         if (sh->ddf_layout)
 148                 /* ddf always start from first device */
 149                 return 0;
 150         /* md starts just after Q block */
 151         if (sh->qd_idx == sh->disks - 1)
 152                 return 0;
 153         else
 154                 return sh->qd_idx + 1;
 155 }
 156 static inline int raid6_next_disk(int disk, int raid_disks)
 157 {
 158         disk++;
 159         return (disk < raid_disks) ? disk : 0;
 160 }
 161
 162 /* When walking through the disks in a raid5, starting at raid6_d0,
 163  * We need to map each disk to a 'slot', where the data disks are slot
 164  * 0 .. raid_disks-3, the parity disk is raid_disks-2 and the Q disk
 165  * is raid_disks-1.  This help does that mapping.
 166  */
 167 static int raid6_idx_to_slot(int idx, struct stripe_head *sh,
 168                              int *count, int syndrome_disks)
 169 {
 170         int slot = *count;
 171
 172         if (sh->ddf_layout)
 173                 (*count)++;
 174         if (idx == sh->pd_idx)
 175                 return syndrome_disks;
 176         if (idx == sh->qd_idx)
 177                 return syndrome_disks + 1;
 178         if (!sh->ddf_layout)
 179                 (*count)++;
 180         return slot;
 181 }
 182
 183 static void return_io(struct bio *return_bi)
 184 {
 185         struct bio *bi = return_bi;
 186         while (bi) {
 187
 188                 return_bi = bi->bi_next;
 189                 bi->bi_next = NULL;
 190                 bi->bi_size = 0;
 191                 trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
 192                                          bi, 0);
 193                 bio_endio(bi, 0);
 194                 bi = return_bi;
 195         }
 196 }
 197
 198 static void print_raid5_conf (struct r5conf *conf);
 199
 200 static int stripe_operations_active(struct stripe_head *sh)
 201 {
 202         return sh->check_state || sh->reconstruct_state ||
 203                test_bit(STRIPE_BIOFILL_RUN, &sh->state) ||
 204                test_bit(STRIPE_COMPUTE_RUN, &sh->state);
 205 }
 206
 207 static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh)
 208 {
 209         BUG_ON(!list_empty(&sh->lru));
 210         BUG_ON(atomic_read(&conf->active_stripes)==0);
 211         if (test_bit(STRIPE_HANDLE, &sh->state)) {
 212                 if (test_bit(STRIPE_DELAYED, &sh->state) &&
 213                     !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 214                         list_add_tail(&sh->lru, &conf->delayed_list);
 215                 else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
 216                            sh->bm_seq - conf->seq_write > 0)
 217                         list_add_tail(&sh->lru, &conf->bitmap_list);
 218                 else {
 219                         clear_bit(STRIPE_DELAYED, &sh->state);
 220                         clear_bit(STRIPE_BIT_DELAY, &sh->state);
 221                         list_add_tail(&sh->lru, &conf->handle_list);
 222                 }
 223                 md_wakeup_thread(conf->mddev->thread);
 224         } else {
 225                 BUG_ON(stripe_operations_active(sh));
 226                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 227                         if (atomic_dec_return(&conf->preread_active_stripes)
 228                             < IO_THRESHOLD)
 229                                 md_wakeup_thread(conf->mddev->thread);
 230                 atomic_dec(&conf->active_stripes);
 231                 if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
 232                         list_add_tail(&sh->lru, &conf->inactive_list);
 233                         wake_up(&conf->wait_for_stripe);
 234                         if (conf->retry_read_aligned)
 235                                 md_wakeup_thread(conf->mddev->thread);
 236                 }
 237         }
 238 }
 239
 240 static void __release_stripe(struct r5conf *conf, struct stripe_head *sh)
 241 {
 242         if (atomic_dec_and_test(&sh->count))
 243                 do_release_stripe(conf, sh);
 244 }
 245
 246 static void release_stripe(struct stripe_head *sh)
 247 {
 248         struct r5conf *conf = sh->raid_conf;
 249         unsigned long flags;
 250
 251         local_irq_save(flags);
 252         if (atomic_dec_and_lock(&sh->count, &conf->device_lock)) {
 253                 do_release_stripe(conf, sh);
 254                 spin_unlock(&conf->device_lock);
 255         }
 256         local_irq_restore(flags);
 257 }
 258
 259 static inline void remove_hash(struct stripe_head *sh)
 260 {
 261         pr_debug("remove_hash(), stripe %llu\n",
 262                 (unsigned long long)sh->sector);
 263
 264         hlist_del_init(&sh->hash);
 265 }
 266
 267 static inline void insert_hash(struct r5conf *conf, struct stripe_head *sh)
 268 {
 269         struct hlist_head *hp = stripe_hash(conf, sh->sector);
 270
 271         pr_debug("insert_hash(), stripe %llu\n",
 272                 (unsigned long long)sh->sector);
 273
 274         hlist_add_head(&sh->hash, hp);
 275 }
 276
 277
 278 /* find an idle stripe, make sure it is unhashed, and return it. */
 279 static struct stripe_head *get_free_stripe(struct r5conf *conf)
 280 {
 281         struct stripe_head *sh = NULL;
 282         struct list_head *first;
 283
 284         if (list_empty(&conf->inactive_list))
 285                 goto out;
 286         first = conf->inactive_list.next;
 287         sh = list_entry(first, struct stripe_head, lru);
 288         list_del_init(first);
 289         remove_hash(sh);
 290         atomic_inc(&conf->active_stripes);
 291 out:
 292         return sh;
 293 }
 294
 295 static void shrink_buffers(struct stripe_head *sh)
 296 {
 297         struct page *p;
 298         int i;
 299         int num = sh->raid_conf->pool_size;
 300
 301         for (i = 0; i < num ; i++) {
 302                 p = sh->dev[i].page;
 303                 if (!p)
 304                         continue;
 305                 sh->dev[i].page = NULL;
 306                 put_page(p);
 307         }
 308 }
 309
 310 static int grow_buffers(struct stripe_head *sh)
 311 {
 312         int i;
 313         int num = sh->raid_conf->pool_size;
 314
 315         for (i = 0; i < num; i++) {
 316                 struct page *page;
 317
 318                 if (!(page = alloc_page(GFP_KERNEL))) {
 319                         return 1;
 320                 }
 321                 sh->dev[i].page = page;
 322         }
 323         return 0;
 324 }
 325
 326 static void raid5_build_block(struct stripe_head *sh, int i, int previous);
 327 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
 328                             struct stripe_head *sh);
 329
 330 static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
 331 {
 332         struct r5conf *conf = sh->raid_conf;
 333         int i;
 334
 335         BUG_ON(atomic_read(&sh->count) != 0);
 336         BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
 337         BUG_ON(stripe_operations_active(sh));
 338
 339         pr_debug("init_stripe called, stripe %llu\n",
 340                 (unsigned long long)sh->sector);
 341
 342         remove_hash(sh);
 343
 344         sh->generation = conf->generation - previous;
 345         sh->disks = previous ? conf->previous_raid_disks : conf->raid_disks;
 346         sh->sector = sector;
 347         stripe_set_idx(sector, conf, previous, sh);
 348         sh->state = 0;
 349
 350
 351         for (i = sh->disks; i--; ) {
 352                 struct r5dev *dev = &sh->dev[i];
 353
 354                 if (dev->toread || dev->read || dev->towrite || dev->written ||
 355                     test_bit(R5_LOCKED, &dev->flags)) {
 356                         printk(KERN_ERR "sector=%llx i=%d %p %p %p %p %d\n",
 357                                (unsigned long long)sh->sector, i, dev->toread,
 358                                dev->read, dev->towrite, dev->written,
 359                                test_bit(R5_LOCKED, &dev->flags));
 360                         WARN_ON(1);
 361                 }
 362                 dev->flags = 0;
 363                 raid5_build_block(sh, i, previous);
 364         }
 365         insert_hash(conf, sh);
 366 }
 367
 368 static struct stripe_head *__find_stripe(struct r5conf *conf, sector_t sector,
 369                                          short generation)
 370 {
 371         struct stripe_head *sh;
 372
 373         pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
 374         hlist_for_each_entry(sh, stripe_hash(conf, sector), hash)
 375                 if (sh->sector == sector && sh->generation == generation)
 376                         return sh;
 377         pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
 378         return NULL;
 379 }
 380
 381 /*
 382  * Need to check if array has failed when deciding whether to:
 383  *  - start an array
 384  *  - remove non-faulty devices
 385  *  - add a spare
 386  *  - allow a reshape
 387  * This determination is simple when no reshape is happening.
 388  * However if there is a reshape, we need to carefully check
 389  * both the before and after sections.
 390  * This is because some failed devices may only affect one
 391  * of the two sections, and some non-in_sync devices may
 392  * be insync in the section most affected by failed devices.
 393  */
 394 static int calc_degraded(struct r5conf *conf)
 395 {
 396         int degraded, degraded2;
 397         int i;
 398
 399         rcu_read_lock();
 400         degraded = 0;
 401         for (i = 0; i < conf->previous_raid_disks; i++) {
 402                 struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
 403                 if (rdev && test_bit(Faulty, &rdev->flags))
 404                         rdev = rcu_dereference(conf->disks[i].replacement);
 405                 if (!rdev || test_bit(Faulty, &rdev->flags))
 406                         degraded++;
 407                 else if (test_bit(In_sync, &rdev->flags))
 408                         ;
 409                 else
 410                         /* not in-sync or faulty.
 411                          * If the reshape increases the number of devices,
 412                          * this is being recovered by the reshape, so
 413                          * this 'previous' section is not in_sync.
 414                          * If the number of devices is being reduced however,
 415                          * the device can only be part of the array if
 416                          * we are reverting a reshape, so this section will
 417                          * be in-sync.
 418                          */
 419                         if (conf->raid_disks >= conf->previous_raid_disks)
 420                                 degraded++;
 421         }
 422         rcu_read_unlock();
 423         if (conf->raid_disks == conf->previous_raid_disks)
 424                 return degraded;
 425         rcu_read_lock();
 426         degraded2 = 0;
 427         for (i = 0; i < conf->raid_disks; i++) {
 428                 struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
 429                 if (rdev && test_bit(Faulty, &rdev->flags))
 430                         rdev = rcu_dereference(conf->disks[i].replacement);
 431                 if (!rdev || test_bit(Faulty, &rdev->flags))
 432                         degraded2++;
 433                 else if (test_bit(In_sync, &rdev->flags))
 434                         ;
 435                 else
 436                         /* not in-sync or faulty.
 437                          * If reshape increases the number of devices, this
 438                          * section has already been recovered, else it
 439                          * almost certainly hasn't.
 440                          */
 441                         if (conf->raid_disks <= conf->previous_raid_disks)
 442                                 degraded2++;
 443         }
 444         rcu_read_unlock();
 445         if (degraded2 > degraded)
 446                 return degraded2;
 447         return degraded;
 448 }
 449
 450 static int has_failed(struct r5conf *conf)
 451 {
 452         int degraded;
 453
 454         if (conf->mddev->reshape_position == MaxSector)
 455                 return conf->mddev->degraded > conf->max_degraded;
 456
 457         degraded = calc_degraded(conf);
 458         if (degraded > conf->max_degraded)
 459                 return 1;
 460         return 0;
 461 }
 462
 463 static struct stripe_head *
 464 get_active_stripe(struct r5conf *conf, sector_t sector,
 465                   int previous, int noblock, int noquiesce)
 466 {
 467         struct stripe_head *sh;
 468
 469         pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
 470
 471         spin_lock_irq(&conf->device_lock);
 472
 473         do {
 474                 wait_event_lock_irq(conf->wait_for_stripe,
 475                                     conf->quiesce == 0 || noquiesce,
 476                                     conf->device_lock);
 477                 sh = __find_stripe(conf, sector, conf->generation - previous);
 478                 if (!sh) {
 479                         if (!conf->inactive_blocked)
 480                                 sh = get_free_stripe(conf);
 481                         if (noblock && sh == NULL)
 482                                 break;
 483                         if (!sh) {
 484                                 conf->inactive_blocked = 1;
 485                                 wait_event_lock_irq(conf->wait_for_stripe,
 486                                                     !list_empty(&conf->inactive_list) &&
 487                                                     (atomic_read(&conf->active_stripes)
 488                                                      < (conf->max_nr_stripes *3/4)
 489                                                      || !conf->inactive_blocked),
 490                                                     conf->device_lock);
 491                                 conf->inactive_blocked = 0;
 492                         } else
 493                                 init_stripe(sh, sector, previous);
 494                 } else {
 495                         if (atomic_read(&sh->count)) {
 496                                 BUG_ON(!list_empty(&sh->lru)
 497                                     && !test_bit(STRIPE_EXPANDING, &sh->state)
 498                                     && !test_bit(STRIPE_ON_UNPLUG_LIST, &sh->state));
 499                         } else {
 500                                 if (!test_bit(STRIPE_HANDLE, &sh->state))
 501                                         atomic_inc(&conf->active_stripes);
 502                                 if (list_empty(&sh->lru) &&
 503                                     !test_bit(STRIPE_EXPANDING, &sh->state))
 504                                         BUG();
 505                                 list_del_init(&sh->lru);
 506                         }
 507                 }
 508         } while (sh == NULL);
 509
 510         if (sh)
 511                 atomic_inc(&sh->count);
 512
 513         spin_unlock_irq(&conf->device_lock);
 514         return sh;
 515 }
 516
 517 /* Determine if 'data_offset' or 'new_data_offset' should be used
 518  * in this stripe_head.
 519  */
 520 static int use_new_offset(struct r5conf *conf, struct stripe_head *sh)
 521 {
 522         sector_t progress = conf->reshape_progress;
 523         /* Need a memory barrier to make sure we see the value
 524          * of conf->generation, or ->data_offset that was set before
 525          * reshape_progress was updated.
 526          */
 527         smp_rmb();
 528         if (progress == MaxSector)
 529                 return 0;
 530         if (sh->generation == conf->generation - 1)
 531                 return 0;
 532         /* We are in a reshape, and this is a new-generation stripe,
 533          * so use new_data_offset.
 534          */
 535         return 1;
 536 }
 537
 538 static void
 539 raid5_end_read_request(struct bio *bi, int error);
 540 static void
 541 raid5_end_write_request(struct bio *bi, int error);
 542
 543 static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
 544 {
 545         struct r5conf *conf = sh->raid_conf;
 546         int i, disks = sh->disks;
 547
 548         might_sleep();
 549
 550         for (i = disks; i--; ) {
 551                 int rw;
 552                 int replace_only = 0;
 553                 struct bio *bi, *rbi;
 554                 struct md_rdev *rdev, *rrdev = NULL;
 555                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
 556                         if (test_and_clear_bit(R5_WantFUA, &sh->dev[i].flags))
 557                                 rw = WRITE_FUA;
 558                         else
 559                                 rw = WRITE;
 560                         if (test_bit(R5_Discard, &sh->dev[i].flags))
 561                                 rw |= REQ_DISCARD;
 562                 } else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
 563                         rw = READ;
 564                 else if (test_and_clear_bit(R5_WantReplace,
 565                                             &sh->dev[i].flags)) {
 566                         rw = WRITE;
 567                         replace_only = 1;
 568                 } else
 569                         continue;
 570                 if (test_and_clear_bit(R5_SyncIO, &sh->dev[i].flags))
 571                         rw |= REQ_SYNC;
 572
 573                 bi = &sh->dev[i].req;
 574                 rbi = &sh->dev[i].rreq; /* For writing to replacement */
 575
 576                 rcu_read_lock();
 577                 rrdev = rcu_dereference(conf->disks[i].replacement);
 578                 smp_mb(); /* Ensure that if rrdev is NULL, rdev won't be */
 579                 rdev = rcu_dereference(conf->disks[i].rdev);
 580                 if (!rdev) {
 581                         rdev = rrdev;
 582                         rrdev = NULL;
 583                 }
 584                 if (rw & WRITE) {
 585                         if (replace_only)
 586                                 rdev = NULL;
 587                         if (rdev == rrdev)
 588                                 /* We raced and saw duplicates */
 589                                 rrdev = NULL;
 590                 } else {
 591                         if (test_bit(R5_ReadRepl, &sh->dev[i].flags) && rrdev)
 592                                 rdev = rrdev;
 593                         rrdev = NULL;
 594                 }
 595
 596                 if (rdev && test_bit(Faulty, &rdev->flags))
 597                         rdev = NULL;
 598                 if (rdev)
 599                         atomic_inc(&rdev->nr_pending);
 600                 if (rrdev && test_bit(Faulty, &rrdev->flags))
 601                         rrdev = NULL;
 602                 if (rrdev)
 603                         atomic_inc(&rrdev->nr_pending);
 604                 rcu_read_unlock();
 605
 606                 /* We have already checked bad blocks for reads.  Now
 607                  * need to check for writes.  We never accept write errors
 608                  * on the replacement, so we don't to check rrdev.
 609                  */
 610                 while ((rw & WRITE) && rdev &&
 611                        test_bit(WriteErrorSeen, &rdev->flags)) {
 612                         sector_t first_bad;
 613                         int bad_sectors;
 614                         int bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
 615                                               &first_bad, &bad_sectors);
 616                         if (!bad)
 617                                 break;
 618
 619                         if (bad < 0) {
 620                                 set_bit(BlockedBadBlocks, &rdev->flags);
 621                                 if (!conf->mddev->external &&
 622                                     conf->mddev->flags) {
 623                                         /* It is very unlikely, but we might
 624                                          * still need to write out the
 625                                          * bad block log - better give it
 626                                          * a chance*/
 627                                         md_check_recovery(conf->mddev);
 628                                 }
 629                                 /*
 630                                  * Because md_wait_for_blocked_rdev
 631                                  * will dec nr_pending, we must
 632                                  * increment it first.
 633                                  */
 634                                 atomic_inc(&rdev->nr_pending);
 635                                 md_wait_for_blocked_rdev(rdev, conf->mddev);
 636                         } else {
 637                                 /* Acknowledged bad block - skip the write */
 638                                 rdev_dec_pending(rdev, conf->mddev);
 639                                 rdev = NULL;
 640                         }
 641                 }
 642
 643                 if (rdev) {
 644                         if (s->syncing || s->expanding || s->expanded
 645                             || s->replacing)
 646                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
 647
 648                         set_bit(STRIPE_IO_STARTED, &sh->state);
 649
 650                         bio_reset(bi);
 651                         bi->bi_bdev = rdev->bdev;
 652                         bi->bi_rw = rw;
 653                         bi->bi_end_io = (rw & WRITE)
 654                                 ? raid5_end_write_request
 655                                 : raid5_end_read_request;
 656                         bi->bi_private = sh;
 657
 658                         pr_debug("%s: for %llu schedule op %ld on disc %d\n",
 659                                 __func__, (unsigned long long)sh->sector,
 660                                 bi->bi_rw, i);
 661                         atomic_inc(&sh->count);
 662                         if (use_new_offset(conf, sh))
 663                                 bi->bi_sector = (sh->sector
 664                                                  + rdev->new_data_offset);
 665                         else
 666                                 bi->bi_sector = (sh->sector
 667                                                  + rdev->data_offset);
 668                         if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
 669                                 bi->bi_rw |= REQ_FLUSH;
 670
 671                         bi->bi_vcnt = 1;
 672                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
 673                         bi->bi_io_vec[0].bv_offset = 0;
 674                         bi->bi_size = STRIPE_SIZE;
 675                         /*
 676                          * If this is discard request, set bi_vcnt 0. We don't
 677                          * want to confuse SCSI because SCSI will replace payload
 678                          */
 679                         if (rw & REQ_DISCARD)
 680                                 bi->bi_vcnt = 0;
 681                         if (rrdev)
 682                                 set_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags);
 683
 684                         if (conf->mddev->gendisk)
 685                                 trace_block_bio_remap(bdev_get_queue(bi->bi_bdev),
 686                                                       bi, disk_devt(conf->mddev->gendisk),
 687                                                       sh->dev[i].sector);
 688                         generic_make_request(bi);
 689                 }
 690                 if (rrdev) {
 691                         if (s->syncing || s->expanding || s->expanded
 692                             || s->replacing)
 693                                 md_sync_acct(rrdev->bdev, STRIPE_SECTORS);
 694
 695                         set_bit(STRIPE_IO_STARTED, &sh->state);
 696
 697                         bio_reset(rbi);
 698                         rbi->bi_bdev = rrdev->bdev;
 699                         rbi->bi_rw = rw;
 700                         BUG_ON(!(rw & WRITE));
 701                         rbi->bi_end_io = raid5_end_write_request;
 702                         rbi->bi_private = sh;
 703
 704                         pr_debug("%s: for %llu schedule op %ld on "
 705                                  "replacement disc %d\n",
 706                                 __func__, (unsigned long long)sh->sector,
 707                                 rbi->bi_rw, i);
 708                         atomic_inc(&sh->count);
 709                         if (use_new_offset(conf, sh))
 710                                 rbi->bi_sector = (sh->sector
 711                                                   + rrdev->new_data_offset);
 712                         else
 713                                 rbi->bi_sector = (sh->sector
 714                                                   + rrdev->data_offset);
 715                         rbi->bi_vcnt = 1;
 716                         rbi->bi_io_vec[0].bv_len = STRIPE_SIZE;
 717                         rbi->bi_io_vec[0].bv_offset = 0;
 718                         rbi->bi_size = STRIPE_SIZE;
 719                         /*
 720                          * If this is discard request, set bi_vcnt 0. We don't
 721                          * want to confuse SCSI because SCSI will replace payload
 722                          */
 723                         if (rw & REQ_DISCARD)
 724                                 rbi->bi_vcnt = 0;
 725                         if (conf->mddev->gendisk)
 726                                 trace_block_bio_remap(bdev_get_queue(rbi->bi_bdev),
 727                                                       rbi, disk_devt(conf->mddev->gendisk),
 728                                                       sh->dev[i].sector);
 729                         generic_make_request(rbi);
 730                 }
 731                 if (!rdev && !rrdev) {
 732                         if (rw & WRITE)
 733                                 set_bit(STRIPE_DEGRADED, &sh->state);
 734                         pr_debug("skip op %ld on disc %d for sector %llu\n",
 735                                 bi->bi_rw, i, (unsigned long long)sh->sector);
 736                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
 737                         set_bit(STRIPE_HANDLE, &sh->state);
 738                 }
 739         }
 740 }
 741
 742 static struct dma_async_tx_descriptor *
 743 async_copy_data(int frombio, struct bio *bio, struct page *page,
 744         sector_t sector, struct dma_async_tx_descriptor *tx)
 745 {
 746         struct bio_vec *bvl;
 747         struct page *bio_page;
 748         int i;
 749         int page_offset;
 750         struct async_submit_ctl submit;
 751         enum async_tx_flags flags = 0;
 752
 753         if (bio->bi_sector >= sector)
 754                 page_offset = (signed)(bio->bi_sector - sector) * 512;
 755         else
 756                 page_offset = (signed)(sector - bio->bi_sector) * -512;
 757
 758         if (frombio)
 759                 flags |= ASYNC_TX_FENCE;
 760         init_async_submit(&submit, flags, tx, NULL, NULL, NULL);
 761
 762         bio_for_each_segment(bvl, bio, i) {
 763                 int len = bvl->bv_len;
 764                 int clen;
 765                 int b_offset = 0;
 766
 767                 if (page_offset < 0) {
 768                         b_offset = -page_offset;
 769                         page_offset += b_offset;
 770                         len -= b_offset;
 771                 }
 772
 773                 if (len > 0 && page_offset + len > STRIPE_SIZE)
 774                         clen = STRIPE_SIZE - page_offset;
 775                 else
 776                         clen = len;
 777
 778                 if (clen > 0) {
 779                         b_offset += bvl->bv_offset;
 780                         bio_page = bvl->bv_page;
 781                         if (frombio)
 782                                 tx = async_memcpy(page, bio_page, page_offset,
 783                                                   b_offset, clen, &submit);
 784                         else
 785                                 tx = async_memcpy(bio_page, page, b_offset,
 786                                                   page_offset, clen, &submit);
 787                 }
 788                 /* chain the operations */
 789                 submit.depend_tx = tx;
 790
 791                 if (clen < len) /* hit end of page */
 792                         break;
 793                 page_offset +=  len;
 794         }
 795
 796         return tx;
 797 }
 798
 799 static void ops_complete_biofill(void *stripe_head_ref)
 800 {
 801         struct stripe_head *sh = stripe_head_ref;
 802         struct bio *return_bi = NULL;
 803         int i;
 804
 805         pr_debug("%s: stripe %llu\n", __func__,
 806                 (unsigned long long)sh->sector);
 807
 808         /* clear completed biofills */
 809         for (i = sh->disks; i--; ) {
 810                 struct r5dev *dev = &sh->dev[i];
 811
 812                 /* acknowledge completion of a biofill operation */
 813                 /* and check if we need to reply to a read request,
 814                  * new R5_Wantfill requests are held off until
 815                  * !STRIPE_BIOFILL_RUN
 816                  */
 817                 if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
 818                         struct bio *rbi, *rbi2;
 819
 820                         BUG_ON(!dev->read);
 821                         rbi = dev->read;
 822                         dev->read = NULL;
 823                         while (rbi && rbi->bi_sector <
 824                                 dev->sector + STRIPE_SECTORS) {
 825                                 rbi2 = r5_next_bio(rbi, dev->sector);
 826                                 if (!raid5_dec_bi_active_stripes(rbi)) {
 827                                         rbi->bi_next = return_bi;
 828                                         return_bi = rbi;
 829                                 }
 830                                 rbi = rbi2;
 831                         }
 832                 }
 833         }
 834         clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
 835
 836         return_io(return_bi);
 837
 838         set_bit(STRIPE_HANDLE, &sh->state);
 839         release_stripe(sh);
 840 }
 841
 842 static void ops_run_biofill(struct stripe_head *sh)
 843 {
 844         struct dma_async_tx_descriptor *tx = NULL;
 845         struct async_submit_ctl submit;
 846         int i;
 847
 848         pr_debug("%s: stripe %llu\n", __func__,
 849                 (unsigned long long)sh->sector);
 850
 851         for (i = sh->disks; i--; ) {
 852                 struct r5dev *dev = &sh->dev[i];
 853                 if (test_bit(R5_Wantfill, &dev->flags)) {
 854                         struct bio *rbi;
 855                         spin_lock_irq(&sh->stripe_lock);
 856                         dev->read = rbi = dev->toread;
 857                         dev->toread = NULL;
 858                         spin_unlock_irq(&sh->stripe_lock);
 859                         while (rbi && rbi->bi_sector <
 860                                 dev->sector + STRIPE_SECTORS) {
 861                                 tx = async_copy_data(0, rbi, dev->page,
 862                                         dev->sector, tx);
 863                                 rbi = r5_next_bio(rbi, dev->sector);
 864                         }
 865                 }
 866         }
 867
 868         atomic_inc(&sh->count);
 869         init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_biofill, sh, NULL);
 870         async_trigger_callback(&submit);
 871 }
 872
 873 static void mark_target_uptodate(struct stripe_head *sh, int target)
 874 {
 875         struct r5dev *tgt;
 876
 877         if (target < 0)
 878                 return;
 879
 880         tgt = &sh->dev[target];
 881         set_bit(R5_UPTODATE, &tgt->flags);
 882         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
 883         clear_bit(R5_Wantcompute, &tgt->flags);
 884 }
 885
 886 static void ops_complete_compute(void *stripe_head_ref)
 887 {
 888         struct stripe_head *sh = stripe_head_ref;
 889
 890         pr_debug("%s: stripe %llu\n", __func__,
 891                 (unsigned long long)sh->sector);
 892
 893         /* mark the computed target(s) as uptodate */
 894         mark_target_uptodate(sh, sh->ops.target);
 895         mark_target_uptodate(sh, sh->ops.target2);
 896
 897         clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
 898         if (sh->check_state == check_state_compute_run)
 899                 sh->check_state = check_state_compute_result;
 900         set_bit(STRIPE_HANDLE, &sh->state);
 901         release_stripe(sh);
 902 }
 903
 904 /* return a pointer to the address conversion region of the scribble buffer */
 905 static addr_conv_t *to_addr_conv(struct stripe_head *sh,
 906                                  struct raid5_percpu *percpu)
 907 {
 908         return percpu->scribble + sizeof(struct page *) * (sh->disks + 2);
 909 }
 910
 911 static struct dma_async_tx_descriptor *
 912 ops_run_compute5(struct stripe_head *sh, struct raid5_percpu *percpu)
 913 {
 914         int disks = sh->disks;
 915         struct page **xor_srcs = percpu->scribble;
 916         int target = sh->ops.target;
 917         struct r5dev *tgt = &sh->dev[target];
 918         struct page *xor_dest = tgt->page;
 919         int count = 0;
 920         struct dma_async_tx_descriptor *tx;
 921         struct async_submit_ctl submit;
 922         int i;
 923
 924         pr_debug("%s: stripe %llu block: %d\n",
 925                 __func__, (unsigned long long)sh->sector, target);
 926         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
 927
 928         for (i = disks; i--; )
 929                 if (i != target)
 930                         xor_srcs[count++] = sh->dev[i].page;
 931
 932         atomic_inc(&sh->count);
 933
 934         init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, NULL,
 935                           ops_complete_compute, sh, to_addr_conv(sh, percpu));
 936         if (unlikely(count == 1))
 937                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
 938         else
 939                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
 940
 941         return tx;
 942 }
 943
 944 /* set_syndrome_sources - populate source buffers for gen_syndrome
 945  * @srcs - (struct page *) array of size sh->disks
 946  * @sh - stripe_head to parse
 947  *
 948  * Populates srcs in proper layout order for the stripe and returns the
 949  * 'count' of sources to be used in a call to async_gen_syndrome.  The P
 950  * destination buffer is recorded in srcs[count] and the Q destination
 951  * is recorded in srcs[count+1]].
 952  */
 953 static int set_syndrome_sources(struct page **srcs, struct stripe_head *sh)
 954 {
 955         int disks = sh->disks;
 956         int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
 957         int d0_idx = raid6_d0(sh);
 958         int count;
 959         int i;
 960
 961         for (i = 0; i < disks; i++)
 962                 srcs[i] = NULL;
 963
 964         count = 0;
 965         i = d0_idx;
 966         do {
 967                 int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
 968
 969                 srcs[slot] = sh->dev[i].page;
 970                 i = raid6_next_disk(i, disks);
 971         } while (i != d0_idx);
 972
 973         return syndrome_disks;
 974 }
 975
 976 static struct dma_async_tx_descriptor *
 977 ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
 978 {
 979         int disks = sh->disks;
 980         struct page **blocks = percpu->scribble;
 981         int target;
 982         int qd_idx = sh->qd_idx;
 983         struct dma_async_tx_descriptor *tx;
 984         struct async_submit_ctl submit;
 985         struct r5dev *tgt;
 986         struct page *dest;
 987         int i;
 988         int count;
 989
 990         if (sh->ops.target < 0)
 991                 target = sh->ops.target2;
 992         else if (sh->ops.target2 < 0)
 993                 target = sh->ops.target;
 994         else
 995                 /* we should only have one valid target */
 996                 BUG();
 997         BUG_ON(target < 0);
 998         pr_debug("%s: stripe %llu block: %d\n",
 999                 __func__, (unsigned long long)sh->sector, target);
1000
1001         tgt = &sh->dev[target];
1002         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1003         dest = tgt->page;
1004
1005         atomic_inc(&sh->count);
1006
1007         if (target == qd_idx) {
1008                 count = set_syndrome_sources(blocks, sh);
1009                 blocks[count] = NULL; /* regenerating p is not necessary */
1010                 BUG_ON(blocks[count+1] != dest); /* q should already be set */
1011                 init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1012                                   ops_complete_compute, sh,
1013                                   to_addr_conv(sh, percpu));
1014                 tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE, &submit);
1015         } else {
1016                 /* Compute any data- or p-drive using XOR */
1017                 count = 0;
1018                 for (i = disks; i-- ; ) {
1019                         if (i == target || i == qd_idx)
1020                                 continue;
1021                         blocks[count++] = sh->dev[i].page;
1022                 }
1023
1024                 init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1025                                   NULL, ops_complete_compute, sh,
1026                                   to_addr_conv(sh, percpu));
1027                 tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE, &submit);
1028         }
1029
1030         return tx;
1031 }
1032
1033 static struct dma_async_tx_descriptor *
1034 ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
1035 {
1036         int i, count, disks = sh->disks;
1037         int syndrome_disks = sh->ddf_layout ? disks : disks-2;
1038         int d0_idx = raid6_d0(sh);
1039         int faila = -1, failb = -1;
1040         int target = sh->ops.target;
1041         int target2 = sh->ops.target2;
1042         struct r5dev *tgt = &sh->dev[target];
1043         struct r5dev *tgt2 = &sh->dev[target2];
1044         struct dma_async_tx_descriptor *tx;
1045         struct page **blocks = percpu->scribble;
1046         struct async_submit_ctl submit;
1047
1048         pr_debug("%s: stripe %llu block1: %d block2: %d\n",
1049                  __func__, (unsigned long long)sh->sector, target, target2);
1050         BUG_ON(target < 0 || target2 < 0);
1051         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1052         BUG_ON(!test_bit(R5_Wantcompute, &tgt2->flags));
1053
1054         /* we need to open-code set_syndrome_sources to handle the
1055          * slot number conversion for 'faila' and 'failb'
1056          */
1057         for (i = 0; i < disks ; i++)
1058                 blocks[i] = NULL;
1059         count = 0;
1060         i = d0_idx;
1061         do {
1062                 int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1063
1064                 blocks[slot] = sh->dev[i].page;
1065
1066                 if (i == target)
1067                         faila = slot;
1068                 if (i == target2)
1069                         failb = slot;
1070                 i = raid6_next_disk(i, disks);
1071         } while (i != d0_idx);
1072
1073         BUG_ON(faila == failb);
1074         if (failb < faila)
1075                 swap(faila, failb);
1076         pr_debug("%s: stripe: %llu faila: %d failb: %d\n",
1077                  __func__, (unsigned long long)sh->sector, faila, failb);
1078
1079         atomic_inc(&sh->count);
1080
1081         if (failb == syndrome_disks+1) {
1082                 /* Q disk is one of the missing disks */
1083                 if (faila == syndrome_disks) {
1084                         /* Missing P+Q, just recompute */
1085                         init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1086                                           ops_complete_compute, sh,
1087                                           to_addr_conv(sh, percpu));
1088                         return async_gen_syndrome(blocks, 0, syndrome_disks+2,
1089                                                   STRIPE_SIZE, &submit);
1090                 } else {
1091                         struct page *dest;
1092                         int data_target;
1093                         int qd_idx = sh->qd_idx;
1094
1095                         /* Missing D+Q: recompute D from P, then recompute Q */
1096                         if (target == qd_idx)
1097                                 data_target = target2;
1098                         else
1099                                 data_target = target;
1100
1101                         count = 0;
1102                         for (i = disks; i-- ; ) {
1103                                 if (i == data_target || i == qd_idx)
1104                                         continue;
1105                                 blocks[count++] = sh->dev[i].page;
1106                         }
1107                         dest = sh->dev[data_target].page;
1108                         init_async_submit(&submit,
1109                                           ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1110                                           NULL, NULL, NULL,
1111                                           to_addr_conv(sh, percpu));
1112                         tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE,
1113                                        &submit);
1114
1115                         count = set_syndrome_sources(blocks, sh);
1116                         init_async_submit(&submit, ASYNC_TX_FENCE, tx,
1117                                           ops_complete_compute, sh,
1118                                           to_addr_conv(sh, percpu));
1119                         return async_gen_syndrome(blocks, 0, count+2,
1120                                                   STRIPE_SIZE, &submit);
1121                 }
1122         } else {
1123                 init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1124                                   ops_complete_compute, sh,
1125                                   to_addr_conv(sh, percpu));
1126                 if (failb == syndrome_disks) {
1127                         /* We're missing D+P. */
1128                         return async_raid6_datap_recov(syndrome_disks+2,
1129                                                        STRIPE_SIZE, faila,
1130                                                        blocks, &submit);
1131                 } else {
1132                         /* We're missing D+D. */
1133                         return async_raid6_2data_recov(syndrome_disks+2,
1134                                                        STRIPE_SIZE, faila, failb,
1135                                                        blocks, &submit);
1136                 }
1137         }
1138 }
1139
1140
1141 static void ops_complete_prexor(void *stripe_head_ref)
1142 {
1143         struct stripe_head *sh = stripe_head_ref;
1144
1145         pr_debug("%s: stripe %llu\n", __func__,
1146                 (unsigned long long)sh->sector);
1147 }
1148
1149 static struct dma_async_tx_descriptor *
1150 ops_run_prexor(struct stripe_head *sh, struct raid5_percpu *percpu,
1151                struct dma_async_tx_descriptor *tx)
1152 {
1153         int disks = sh->disks;
1154         struct page **xor_srcs = percpu->scribble;
1155         int count = 0, pd_idx = sh->pd_idx, i;
1156         struct async_submit_ctl submit;
1157
1158         /* existing parity data subtracted */
1159         struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1160
1161         pr_debug("%s: stripe %llu\n", __func__,
1162                 (unsigned long long)sh->sector);
1163
1164         for (i = disks; i--; ) {
1165                 struct r5dev *dev = &sh->dev[i];
1166                 /* Only process blocks that are known to be uptodate */
1167                 if (test_bit(R5_Wantdrain, &dev->flags))
1168                         xor_srcs[count++] = dev->page;
1169         }
1170
1171         init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
1172                           ops_complete_prexor, sh, to_addr_conv(sh, percpu));
1173         tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1174
1175         return tx;
1176 }
1177
1178 static struct dma_async_tx_descriptor *
1179 ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
1180 {
1181         int disks = sh->disks;
1182         int i;
1183
1184         pr_debug("%s: stripe %llu\n", __func__,
1185                 (unsigned long long)sh->sector);
1186
1187         for (i = disks; i--; ) {
1188                 struct r5dev *dev = &sh->dev[i];
1189                 struct bio *chosen;
1190
1191                 if (test_and_clear_bit(R5_Wantdrain, &dev->flags)) {
1192                         struct bio *wbi;
1193
1194                         spin_lock_irq(&sh->stripe_lock);
1195                         chosen = dev->towrite;
1196                         dev->towrite = NULL;
1197                         BUG_ON(dev->written);
1198                         wbi = dev->written = chosen;
1199                         spin_unlock_irq(&sh->stripe_lock);
1200
1201                         while (wbi && wbi->bi_sector <
1202                                 dev->sector + STRIPE_SECTORS) {
1203                                 if (wbi->bi_rw & REQ_FUA)
1204                                         set_bit(R5_WantFUA, &dev->flags);
1205                                 if (wbi->bi_rw & REQ_SYNC)
1206                                         set_bit(R5_SyncIO, &dev->flags);
1207                                 if (wbi->bi_rw & REQ_DISCARD)
1208                                         set_bit(R5_Discard, &dev->flags);
1209                                 else
1210                                         tx = async_copy_data(1, wbi, dev->page,
1211                                                 dev->sector, tx);
1212                                 wbi = r5_next_bio(wbi, dev->sector);
1213                         }
1214                 }
1215         }
1216
1217         return tx;
1218 }
1219
1220 static void ops_complete_reconstruct(void *stripe_head_ref)
1221 {
1222         struct stripe_head *sh = stripe_head_ref;
1223         int disks = sh->disks;
1224         int pd_idx = sh->pd_idx;
1225         int qd_idx = sh->qd_idx;
1226         int i;
1227         bool fua = false, sync = false, discard = false;
1228
1229         pr_debug("%s: stripe %llu\n", __func__,
1230                 (unsigned long long)sh->sector);
1231
1232         for (i = disks; i--; ) {
1233                 fua |= test_bit(R5_WantFUA, &sh->dev[i].flags);
1234                 sync |= test_bit(R5_SyncIO, &sh->dev[i].flags);
1235                 discard |= test_bit(R5_Discard, &sh->dev[i].flags);
1236         }
1237
1238         for (i = disks; i--; ) {
1239                 struct r5dev *dev = &sh->dev[i];
1240
1241                 if (dev->written || i == pd_idx || i == qd_idx) {
1242                         if (!discard)
1243                                 set_bit(R5_UPTODATE, &dev->flags);
1244                         if (fua)
1245                                 set_bit(R5_WantFUA, &dev->flags);
1246                         if (sync)
1247                                 set_bit(R5_SyncIO, &dev->flags);
1248                 }
1249         }
1250
1251         if (sh->reconstruct_state == reconstruct_state_drain_run)
1252                 sh->reconstruct_state = reconstruct_state_drain_result;
1253         else if (sh->reconstruct_state == reconstruct_state_prexor_drain_run)
1254                 sh->reconstruct_state = reconstruct_state_prexor_drain_result;
1255         else {
1256                 BUG_ON(sh->reconstruct_state != reconstruct_state_run);
1257                 sh->reconstruct_state = reconstruct_state_result;
1258         }
1259
1260         set_bit(STRIPE_HANDLE, &sh->state);
1261         release_stripe(sh);
1262 }
1263
1264 static void
1265 ops_run_reconstruct5(struct stripe_head *sh, struct raid5_percpu *percpu,
1266                      struct dma_async_tx_descriptor *tx)
1267 {
1268         int disks = sh->disks;
1269         struct page **xor_srcs = percpu->scribble;
1270         struct async_submit_ctl submit;
1271         int count = 0, pd_idx = sh->pd_idx, i;
1272         struct page *xor_dest;
1273         int prexor = 0;
1274         unsigned long flags;
1275
1276         pr_debug("%s: stripe %llu\n", __func__,
1277                 (unsigned long long)sh->sector);
1278
1279         for (i = 0; i < sh->disks; i++) {
1280                 if (pd_idx == i)
1281                         continue;
1282                 if (!test_bit(R5_Discard, &sh->dev[i].flags))
1283                         break;
1284         }
1285         if (i >= sh->disks) {
1286                 atomic_inc(&sh->count);
1287                 set_bit(R5_Discard, &sh->dev[pd_idx].flags);
1288                 ops_complete_reconstruct(sh);
1289                 return;
1290         }
1291         /* check if prexor is active which means only process blocks
1292          * that are part of a read-modify-write (written)
1293          */
1294         if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1295                 prexor = 1;
1296                 xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1297                 for (i = disks; i--; ) {
1298                         struct r5dev *dev = &sh->dev[i];
1299                         if (dev->written)
1300                                 xor_srcs[count++] = dev->page;
1301                 }
1302         } else {
1303                 xor_dest = sh->dev[pd_idx].page;
1304                 for (i = disks; i--; ) {
1305                         struct r5dev *dev = &sh->dev[i];
1306                         if (i != pd_idx)
1307                                 xor_srcs[count++] = dev->page;
1308                 }
1309         }
1310
1311         /* 1/ if we prexor'd then the dest is reused as a source
1312          * 2/ if we did not prexor then we are redoing the parity
1313          * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
1314          * for the synchronous xor case
1315          */
1316         flags = ASYNC_TX_ACK |
1317                 (prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
1318
1319         atomic_inc(&sh->count);
1320
1321         init_async_submit(&submit, flags, tx, ops_complete_reconstruct, sh,
1322                           to_addr_conv(sh, percpu));
1323         if (unlikely(count == 1))
1324                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1325         else
1326                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1327 }
1328
1329 static void
1330 ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
1331                      struct dma_async_tx_descriptor *tx)
1332 {
1333         struct async_submit_ctl submit;
1334         struct page **blocks = percpu->scribble;
1335         int count, i;
1336
1337         pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
1338
1339         for (i = 0; i < sh->disks; i++) {
1340                 if (sh->pd_idx == i || sh->qd_idx == i)
1341                         continue;
1342                 if (!test_bit(R5_Discard, &sh->dev[i].flags))
1343                         break;
1344         }
1345         if (i >= sh->disks) {
1346                 atomic_inc(&sh->count);
1347                 set_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
1348                 set_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
1349                 ops_complete_reconstruct(sh);
1350                 return;
1351         }
1352
1353         count = set_syndrome_sources(blocks, sh);
1354
1355         atomic_inc(&sh->count);
1356
1357         init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_reconstruct,
1358                           sh, to_addr_conv(sh, percpu));
1359         async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1360 }
1361
1362 static void ops_complete_check(void *stripe_head_ref)
1363 {
1364         struct stripe_head *sh = stripe_head_ref;
1365
1366         pr_debug("%s: stripe %llu\n", __func__,
1367                 (unsigned long long)sh->sector);
1368
1369         sh->check_state = check_state_check_result;
1370         set_bit(STRIPE_HANDLE, &sh->state);
1371         release_stripe(sh);
1372 }
1373
1374 static void ops_run_check_p(struct stripe_head *sh, struct raid5_percpu *percpu)
1375 {
1376         int disks = sh->disks;
1377         int pd_idx = sh->pd_idx;
1378         int qd_idx = sh->qd_idx;
1379         struct page *xor_dest;
1380         struct page **xor_srcs = percpu->scribble;
1381         struct dma_async_tx_descriptor *tx;
1382         struct async_submit_ctl submit;
1383         int count;
1384         int i;
1385
1386         pr_debug("%s: stripe %llu\n", __func__,
1387                 (unsigned long long)sh->sector);
1388
1389         count = 0;
1390         xor_dest = sh->dev[pd_idx].page;
1391         xor_srcs[count++] = xor_dest;
1392         for (i = disks; i--; ) {
1393                 if (i == pd_idx || i == qd_idx)
1394                         continue;
1395                 xor_srcs[count++] = sh->dev[i].page;
1396         }
1397
1398         init_async_submit(&submit, 0, NULL, NULL, NULL,
1399                           to_addr_conv(sh, percpu));
1400         tx = async_xor_val(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
1401                            &sh->ops.zero_sum_result, &submit);
1402
1403         atomic_inc(&sh->count);
1404         init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_check, sh, NULL);
1405         tx = async_trigger_callback(&submit);
1406 }
1407
1408 static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu, int checkp)
1409 {
1410         struct page **srcs = percpu->scribble;
1411         struct async_submit_ctl submit;
1412         int count;
1413
1414         pr_debug("%s: stripe %llu checkp: %d\n", __func__,
1415                 (unsigned long long)sh->sector, checkp);
1416
1417         count = set_syndrome_sources(srcs, sh);
1418         if (!checkp)
1419                 srcs[count] = NULL;
1420
1421         atomic_inc(&sh->count);
1422         init_async_submit(&submit, ASYNC_TX_ACK, NULL, ops_complete_check,
1423                           sh, to_addr_conv(sh, percpu));
1424         async_syndrome_val(srcs, 0, count+2, STRIPE_SIZE,
1425                            &sh->ops.zero_sum_result, percpu->spare_page, &submit);
1426 }
1427
1428 static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
1429 {
1430         int overlap_clear = 0, i, disks = sh->disks;
1431         struct dma_async_tx_descriptor *tx = NULL;
1432         struct r5conf *conf = sh->raid_conf;
1433         int level = conf->level;
1434         struct raid5_percpu *percpu;
1435         unsigned long cpu;
1436
1437         cpu = get_cpu();
1438         percpu = per_cpu_ptr(conf->percpu, cpu);
1439         if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
1440                 ops_run_biofill(sh);
1441                 overlap_clear++;
1442         }
1443
1444         if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
1445                 if (level < 6)
1446                         tx = ops_run_compute5(sh, percpu);
1447                 else {
1448                         if (sh->ops.target2 < 0 || sh->ops.target < 0)
1449                                 tx = ops_run_compute6_1(sh, percpu);
1450                         else
1451                                 tx = ops_run_compute6_2(sh, percpu);
1452                 }
1453                 /* terminate the chain if reconstruct is not set to be run */
1454                 if (tx && !test_bit(STRIPE_OP_RECONSTRUCT, &ops_request))
1455                         async_tx_ack(tx);
1456         }
1457
1458         if (test_bit(STRIPE_OP_PREXOR, &ops_request))
1459                 tx = ops_run_prexor(sh, percpu, tx);
1460
1461         if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
1462                 tx = ops_run_biodrain(sh, tx);
1463                 overlap_clear++;
1464         }
1465
1466         if (test_bit(STRIPE_OP_RECONSTRUCT, &ops_request)) {
1467                 if (level < 6)
1468                         ops_run_reconstruct5(sh, percpu, tx);
1469                 else
1470                         ops_run_reconstruct6(sh, percpu, tx);
1471         }
1472
1473         if (test_bit(STRIPE_OP_CHECK, &ops_request)) {
1474                 if (sh->check_state == check_state_run)
1475                         ops_run_check_p(sh, percpu);
1476                 else if (sh->check_state == check_state_run_q)
1477                         ops_run_check_pq(sh, percpu, 0);
1478                 else if (sh->check_state == check_state_run_pq)
1479                         ops_run_check_pq(sh, percpu, 1);
1480                 else
1481                         BUG();
1482         }
1483
1484         if (overlap_clear)
1485                 for (i = disks; i--; ) {
1486                         struct r5dev *dev = &sh->dev[i];
1487                         if (test_and_clear_bit(R5_Overlap, &dev->flags))
1488                                 wake_up(&sh->raid_conf->wait_for_overlap);
1489                 }
1490         put_cpu();
1491 }
1492
1493 static int grow_one_stripe(struct r5conf *conf)
1494 {
1495         struct stripe_head *sh;
1496         sh = kmem_cache_zalloc(conf->slab_cache, GFP_KERNEL);
1497         if (!sh)
1498                 return 0;
1499
1500         sh->raid_conf = conf;
1501
1502         spin_lock_init(&sh->stripe_lock);
1503
1504         if (grow_buffers(sh)) {
1505                 shrink_buffers(sh);
1506                 kmem_cache_free(conf->slab_cache, sh);
1507                 return 0;
1508         }
1509         /* we just created an active stripe so... */
1510         atomic_set(&sh->count, 1);
1511         atomic_inc(&conf->active_stripes);
1512         INIT_LIST_HEAD(&sh->lru);
1513         release_stripe(sh);
1514         return 1;
1515 }
1516
1517 static int grow_stripes(struct r5conf *conf, int num)
1518 {
1519         struct kmem_cache *sc;
1520         int devs = max(conf->raid_disks, conf->previous_raid_disks);
1521
1522         if (conf->mddev->gendisk)
1523                 sprintf(conf->cache_name[0],
1524                         "raid%d-%s", conf->level, mdname(conf->mddev));
1525         else
1526                 sprintf(conf->cache_name[0],
1527                         "raid%d-%p", conf->level, conf->mddev);
1528         sprintf(conf->cache_name[1], "%s-alt", conf->cache_name[0]);
1529
1530         conf->active_name = 0;
1531         sc = kmem_cache_create(conf->cache_name[conf->active_name],
1532                                sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
1533                                0, 0, NULL);
1534         if (!sc)
1535                 return 1;
1536         conf->slab_cache = sc;
1537         conf->pool_size = devs;
1538         while (num--)
1539                 if (!grow_one_stripe(conf))
1540                         return 1;
1541         return 0;
1542 }
1543
1544 /**
1545  * scribble_len - return the required size of the scribble region
1546  * @num - total number of disks in the array
1547  *
1548  * The size must be enough to contain:
1549  * 1/ a struct page pointer for each device in the array +2
1550  * 2/ room to convert each entry in (1) to its corresponding dma
1551  *    (dma_map_page()) or page (page_address()) address.
1552  *
1553  * Note: the +2 is for the destination buffers of the ddf/raid6 case where we
1554  * calculate over all devices (not just the data blocks), using zeros in place
1555  * of the P and Q blocks.
1556  */
1557 static size_t scribble_len(int num)
1558 {
1559         size_t len;
1560
1561         len = sizeof(struct page *) * (num+2) + sizeof(addr_conv_t) * (num+2);
1562
1563         return len;
1564 }
1565
1566 static int resize_stripes(struct r5conf *conf, int newsize)
1567 {
1568         /* Make all the stripes able to hold 'newsize' devices.
1569          * New slots in each stripe get 'page' set to a new page.
1570          *
1571          * This happens in stages:
1572          * 1/ create a new kmem_cache and allocate the required number of
1573          *    stripe_heads.
1574          * 2/ gather all the old stripe_heads and transfer the pages across
1575          *    to the new stripe_heads.  This will have the side effect of
1576          *    freezing the array as once all stripe_heads have been collected,
1577          *    no IO will be possible.  Old stripe heads are freed once their
1578          *    pages have been transferred over, and the old kmem_cache is
1579          *    freed when all stripes are done.
1580          * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
1581          *    we simple return a failre status - no need to clean anything up.
1582          * 4/ allocate new pages for the new slots in the new stripe_heads.
1583          *    If this fails, we don't bother trying the shrink the
1584          *    stripe_heads down again, we just leave them as they are.
1585          *    As each stripe_head is processed the new one is released into
1586          *    active service.
1587          *
1588          * Once step2 is started, we cannot afford to wait for a write,
1589          * so we use GFP_NOIO allocations.
1590          */
1591         struct stripe_head *osh, *nsh;
1592         LIST_HEAD(newstripes);
1593         struct disk_info *ndisks;
1594         unsigned long cpu;
1595         int err;
1596         struct kmem_cache *sc;
1597         int i;
1598
1599         if (newsize <= conf->pool_size)
1600                 return 0; /* never bother to shrink */
1601
1602         err = md_allow_write(conf->mddev);
1603         if (err)
1604                 return err;
1605
1606         /* Step 1 */
1607         sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
1608                                sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
1609                                0, 0, NULL);
1610         if (!sc)
1611                 return -ENOMEM;
1612
1613         for (i = conf->max_nr_stripes; i; i--) {
1614                 nsh = kmem_cache_zalloc(sc, GFP_KERNEL);
1615                 if (!nsh)
1616                         break;
1617
1618                 nsh->raid_conf = conf;
1619                 spin_lock_init(&nsh->stripe_lock);
1620
1621                 list_add(&nsh->lru, &newstripes);
1622         }
1623         if (i) {
1624                 /* didn't get enough, give up */
1625                 while (!list_empty(&newstripes)) {
1626                         nsh = list_entry(newstripes.next, struct stripe_head, lru);
1627                         list_del(&nsh->lru);
1628                         kmem_cache_free(sc, nsh);
1629                 }
1630                 kmem_cache_destroy(sc);
1631                 return -ENOMEM;
1632         }
1633         /* Step 2 - Must use GFP_NOIO now.
1634          * OK, we have enough stripes, start collecting inactive
1635          * stripes and copying them over
1636          */
1637         list_for_each_entry(nsh, &newstripes, lru) {
1638                 spin_lock_irq(&conf->device_lock);
1639                 wait_event_lock_irq(conf->wait_for_stripe,
1640                                     !list_empty(&conf->inactive_list),
1641                                     conf->device_lock);
1642                 osh = get_free_stripe(conf);
1643                 spin_unlock_irq(&conf->device_lock);
1644                 atomic_set(&nsh->count, 1);
1645                 for(i=0; i<conf->pool_size; i++)
1646                         nsh->dev[i].page = osh->dev[i].page;
1647                 for( ; i<newsize; i++)
1648                         nsh->dev[i].page = NULL;
1649                 kmem_cache_free(conf->slab_cache, osh);
1650         }
1651         kmem_cache_destroy(conf->slab_cache);
1652
1653         /* Step 3.
1654          * At this point, we are holding all the stripes so the array
1655          * is completely stalled, so now is a good time to resize
1656          * conf->disks and the scribble region
1657          */
1658         ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
1659         if (ndisks) {
1660                 for (i=0; i<conf->raid_disks; i++)
1661                         ndisks[i] = conf->disks[i];
1662                 kfree(conf->disks);
1663                 conf->disks = ndisks;
1664         } else
1665                 err = -ENOMEM;
1666
1667         get_online_cpus();
1668         conf->scribble_len = scribble_len(newsize);
1669         for_each_present_cpu(cpu) {
1670                 struct raid5_percpu *percpu;
1671                 void *scribble;
1672
1673                 percpu = per_cpu_ptr(conf->percpu, cpu);
1674                 scribble = kmalloc(conf->scribble_len, GFP_NOIO);
1675
1676                 if (scribble) {
1677                         kfree(percpu->scribble);
1678                         percpu->scribble = scribble;
1679                 } else {
1680                         err = -ENOMEM;
1681                         break;
1682                 }
1683         }
1684         put_online_cpus();
1685
1686         /* Step 4, return new stripes to service */
1687         while(!list_empty(&newstripes)) {
1688                 nsh = list_entry(newstripes.next, struct stripe_head, lru);
1689                 list_del_init(&nsh->lru);
1690
1691                 for (i=conf->raid_disks; i < newsize; i++)
1692                         if (nsh->dev[i].page == NULL) {
1693                                 struct page *p = alloc_page(GFP_NOIO);
1694                                 nsh->dev[i].page = p;
1695                                 if (!p)
1696                                         err = -ENOMEM;
1697                         }
1698                 release_stripe(nsh);
1699         }
1700         /* critical section pass, GFP_NOIO no longer needed */
1701
1702         conf->slab_cache = sc;
1703         conf->active_name = 1-conf->active_name;
1704         conf->pool_size = newsize;
1705         return err;
1706 }
1707
1708 static int drop_one_stripe(struct r5conf *conf)
1709 {
1710         struct stripe_head *sh;
1711
1712         spin_lock_irq(&conf->device_lock);
1713         sh = get_free_stripe(conf);
1714         spin_unlock_irq(&conf->device_lock);
1715         if (!sh)
1716                 return 0;
1717         BUG_ON(atomic_read(&sh->count));
1718         shrink_buffers(sh);
1719         kmem_cache_free(conf->slab_cache, sh);
1720         atomic_dec(&conf->active_stripes);
1721         return 1;
1722 }
1723
1724 static void shrink_stripes(struct r5conf *conf)
1725 {
1726         while (drop_one_stripe(conf))
1727                 ;
1728
1729         if (conf->slab_cache)
1730                 kmem_cache_destroy(conf->slab_cache);
1731         conf->slab_cache = NULL;
1732 }
1733
1734 static void raid5_end_read_request(struct bio * bi, int error)
1735 {
1736         struct stripe_head *sh = bi->bi_private;
1737         struct r5conf *conf = sh->raid_conf;
1738         int disks = sh->disks, i;
1739         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1740         char b[BDEVNAME_SIZE];
1741         struct md_rdev *rdev = NULL;
1742         sector_t s;
1743
1744         for (i=0 ; i<disks; i++)
1745                 if (bi == &sh->dev[i].req)
1746                         break;
1747
1748         pr_debug("end_read_request %llu/%d, count: %d, uptodate %d.\n",
1749                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
1750                 uptodate);
1751         if (i == disks) {
1752                 BUG();
1753                 return;
1754         }
1755         if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
1756                 /* If replacement finished while this request was outstanding,
1757                  * 'replacement' might be NULL already.
1758                  * In that case it moved down to 'rdev'.
1759                  * rdev is not removed until all requests are finished.
1760                  */
1761                 rdev = conf->disks[i].replacement;
1762         if (!rdev)
1763                 rdev = conf->disks[i].rdev;
1764
1765         if (use_new_offset(conf, sh))
1766                 s = sh->sector + rdev->new_data_offset;
1767         else
1768                 s = sh->sector + rdev->data_offset;
1769         if (uptodate) {
1770                 set_bit(R5_UPTODATE, &sh->dev[i].flags);
1771                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
1772                         /* Note that this cannot happen on a
1773                          * replacement device.  We just fail those on
1774                          * any error
1775                          */
1776                         printk_ratelimited(
1777                                 KERN_INFO
1778                                 "md/raid:%s: read error corrected"
1779                                 " (%lu sectors at %llu on %s)\n",
1780                                 mdname(conf->mddev), STRIPE_SECTORS,
1781                                 (unsigned long long)s,
1782                                 bdevname(rdev->bdev, b));
1783                         atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
1784                         clear_bit(R5_ReadError, &sh->dev[i].flags);
1785                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
1786                 } else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
1787                         clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
1788
1789                 if (atomic_read(&rdev->read_errors))
1790                         atomic_set(&rdev->read_errors, 0);
1791         } else {
1792                 const char *bdn = bdevname(rdev->bdev, b);
1793                 int retry = 0;
1794                 int set_bad = 0;
1795
1796                 clear_bit(R5_UPTODATE, &sh->dev[i].flags);
1797                 atomic_inc(&rdev->read_errors);
1798                 if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
1799                         printk_ratelimited(
1800                                 KERN_WARNING
1801                                 "md/raid:%s: read error on replacement device "
1802                                 "(sector %llu on %s).\n",
1803                                 mdname(conf->mddev),
1804                                 (unsigned long long)s,
1805                                 bdn);
1806                 else if (conf->mddev->degraded >= conf->max_degraded) {
1807                         set_bad = 1;
1808                         printk_ratelimited(
1809                                 KERN_WARNING
1810                                 "md/raid:%s: read error not correctable "
1811                                 "(sector %llu on %s).\n",
1812                                 mdname(conf->mddev),
1813                                 (unsigned long long)s,
1814                                 bdn);
1815                 } else if (test_bit(R5_ReWrite, &sh->dev[i].flags)) {
1816                         /* Oh, no!!! */
1817                         set_bad = 1;
1818                         printk_ratelimited(
1819                                 KERN_WARNING
1820                                 "md/raid:%s: read error NOT corrected!! "
1821                                 "(sector %llu on %s).\n",
1822                                 mdname(conf->mddev),
1823                                 (unsigned long long)s,
1824                                 bdn);
1825                 } else if (atomic_read(&rdev->read_errors)
1826                          > conf->max_nr_stripes)
1827                         printk(KERN_WARNING
1828                                "md/raid:%s: Too many read errors, failing device %s.\n",
1829                                mdname(conf->mddev), bdn);
1830                 else
1831                         retry = 1;
1832                 if (retry)
1833                         if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags)) {
1834                                 set_bit(R5_ReadError, &sh->dev[i].flags);
1835                                 clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
1836                         } else
1837                                 set_bit(R5_ReadNoMerge, &sh->dev[i].flags);
1838                 else {
1839                         clear_bit(R5_ReadError, &sh->dev[i].flags);
1840                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
1841                         if (!(set_bad
1842                               && test_bit(In_sync, &rdev->flags)
1843                               && rdev_set_badblocks(
1844                                       rdev, sh->sector, STRIPE_SECTORS, 0)))
1845                                 md_error(conf->mddev, rdev);
1846                 }
1847         }
1848         rdev_dec_pending(rdev, conf->mddev);
1849         clear_bit(R5_LOCKED, &sh->dev[i].flags);
1850         set_bit(STRIPE_HANDLE, &sh->state);
1851         release_stripe(sh);
1852 }
1853
1854 static void raid5_end_write_request(struct bio *bi, int error)
1855 {
1856         struct stripe_head *sh = bi->bi_private;
1857         struct r5conf *conf = sh->raid_conf;
1858         int disks = sh->disks, i;
1859         struct md_rdev *uninitialized_var(rdev);
1860         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1861         sector_t first_bad;
1862         int bad_sectors;
1863         int replacement = 0;
1864
1865         for (i = 0 ; i < disks; i++) {
1866                 if (bi == &sh->dev[i].req) {
1867                         rdev = conf->disks[i].rdev;
1868                         break;
1869                 }
1870                 if (bi == &sh->dev[i].rreq) {
1871                         rdev = conf->disks[i].replacement;
1872                         if (rdev)
1873                                 replacement = 1;
1874                         else
1875                                 /* rdev was removed and 'replacement'
1876                                  * replaced it.  rdev is not removed
1877                                  * until all requests are finished.
1878                                  */
1879                                 rdev = conf->disks[i].rdev;
1880                         break;
1881                 }
1882         }
1883         pr_debug("end_write_request %llu/%d, count %d, uptodate: %d.\n",
1884                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
1885                 uptodate);
1886         if (i == disks) {
1887                 BUG();
1888                 return;
1889         }
1890
1891         if (replacement) {
1892                 if (!uptodate)
1893                         md_error(conf->mddev, rdev);
1894                 else if (is_badblock(rdev, sh->sector,
1895                                      STRIPE_SECTORS,
1896                                      &first_bad, &bad_sectors))
1897                         set_bit(R5_MadeGoodRepl, &sh->dev[i].flags);
1898         } else {
1899                 if (!uptodate) {
1900                         set_bit(STRIPE_DEGRADED, &sh->state);
1901                         set_bit(WriteErrorSeen, &rdev->flags);
1902                         set_bit(R5_WriteError, &sh->dev[i].flags);
1903                         if (!test_and_set_bit(WantReplacement, &rdev->flags))
1904                                 set_bit(MD_RECOVERY_NEEDED,
1905                                         &rdev->mddev->recovery);
1906                 } else if (is_badblock(rdev, sh->sector,
1907                                        STRIPE_SECTORS,
1908                                        &first_bad, &bad_sectors)) {
1909                         set_bit(R5_MadeGood, &sh->dev[i].flags);
1910                         if (test_bit(R5_ReadError, &sh->dev[i].flags))
1911                                 /* That was a successful write so make
1912                                  * sure it looks like we already did
1913                                  * a re-write.
1914                                  */
1915                                 set_bit(R5_ReWrite, &sh->dev[i].flags);
1916                 }
1917         }
1918         rdev_dec_pending(rdev, conf->mddev);
1919
1920         if (!test_and_clear_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags))
1921                 clear_bit(R5_LOCKED, &sh->dev[i].flags);
1922         set_bit(STRIPE_HANDLE, &sh->state);
1923         release_stripe(sh);
1924 }
1925
1926 static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous);
1927
1928 static void raid5_build_block(struct stripe_head *sh, int i, int previous)
1929 {
1930         struct r5dev *dev = &sh->dev[i];
1931
1932         bio_init(&dev->req);
1933         dev->req.bi_io_vec = &dev->vec;
1934         dev->req.bi_vcnt++;
1935         dev->req.bi_max_vecs++;
1936         dev->req.bi_private = sh;
1937         dev->vec.bv_page = dev->page;
1938
1939         bio_init(&dev->rreq);
1940         dev->rreq.bi_io_vec = &dev->rvec;
1941         dev->rreq.bi_vcnt++;
1942         dev->rreq.bi_max_vecs++;
1943         dev->rreq.bi_private = sh;
1944         dev->rvec.bv_page = dev->page;
1945
1946         dev->flags = 0;
1947         dev->sector = compute_blocknr(sh, i, previous);
1948 }
1949
1950 static void error(struct mddev *mddev, struct md_rdev *rdev)
1951 {
1952         char b[BDEVNAME_SIZE];
1953         struct r5conf *conf = mddev->private;
1954         unsigned long flags;
1955         pr_debug("raid456: error called\n");
1956
1957         spin_lock_irqsave(&conf->device_lock, flags);
1958         clear_bit(In_sync, &rdev->flags);
1959         mddev->degraded = calc_degraded(conf);
1960         spin_unlock_irqrestore(&conf->device_lock, flags);
1961         set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1962
1963         set_bit(Blocked, &rdev->flags);
1964         set_bit(Faulty, &rdev->flags);
1965         set_bit(MD_CHANGE_DEVS, &mddev->flags);
1966         printk(KERN_ALERT
1967                "md/raid:%s: Disk failure on %s, disabling device.\n"
1968                "md/raid:%s: Operation continuing on %d devices.\n",
1969                mdname(mddev),
1970                bdevname(rdev->bdev, b),
1971                mdname(mddev),
1972                conf->raid_disks - mddev->degraded);
1973 }
1974
1975 /*
1976  * Input: a 'big' sector number,
1977  * Output: index of the data and parity disk, and the sector # in them.
1978  */
1979 static sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
1980                                      int previous, int *dd_idx,
1981                                      struct stripe_head *sh)
1982 {
1983         sector_t stripe, stripe2;
1984         sector_t chunk_number;
1985         unsigned int chunk_offset;
1986         int pd_idx, qd_idx;
1987         int ddf_layout = 0;
1988         sector_t new_sector;
1989         int algorithm = previous ? conf->prev_algo
1990                                  : conf->algorithm;
1991         int sectors_per_chunk = previous ? conf->prev_chunk_sectors
1992                                          : conf->chunk_sectors;
1993         int raid_disks = previous ? conf->previous_raid_disks
1994                                   : conf->raid_disks;
1995         int data_disks = raid_disks - conf->max_degraded;
1996
1997         /* First compute the information on this sector */
1998
1999         /*
2000          * Compute the chunk number and the sector offset inside the chunk
2001          */
2002         chunk_offset = sector_div(r_sector, sectors_per_chunk);
2003         chunk_number = r_sector;
2004
2005         /*
2006          * Compute the stripe number
2007          */
2008         stripe = chunk_number;
2009         *dd_idx = sector_div(stripe, data_disks);
2010         stripe2 = stripe;
2011         /*
2012          * Select the parity disk based on the user selected algorithm.
2013          */
2014         pd_idx = qd_idx = -1;
2015         switch(conf->level) {
2016         case 4:
2017                 pd_idx = data_disks;
2018                 break;
2019         case 5:
2020                 switch (algorithm) {
2021                 case ALGORITHM_LEFT_ASYMMETRIC:
2022                         pd_idx = data_disks - sector_div(stripe2, raid_disks);
2023                         if (*dd_idx >= pd_idx)
2024                                 (*dd_idx)++;
2025                         break;
2026                 case ALGORITHM_RIGHT_ASYMMETRIC:
2027                         pd_idx = sector_div(stripe2, raid_disks);
2028                         if (*dd_idx >= pd_idx)
2029                                 (*dd_idx)++;
2030                         break;
2031                 case ALGORITHM_LEFT_SYMMETRIC:
2032                         pd_idx = data_disks - sector_div(stripe2, raid_disks);
2033                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2034                         break;
2035                 case ALGORITHM_RIGHT_SYMMETRIC:
2036                         pd_idx = sector_div(stripe2, raid_disks);
2037                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2038                         break;
2039                 case ALGORITHM_PARITY_0:
2040                         pd_idx = 0;
2041                         (*dd_idx)++;
2042                         break;
2043                 case ALGORITHM_PARITY_N:
2044                         pd_idx = data_disks;
2045                         break;
2046                 default:
2047                         BUG();
2048                 }
2049                 break;
2050         case 6:
2051
2052                 switch (algorithm) {
2053                 case ALGORITHM_LEFT_ASYMMETRIC:
2054                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2055                         qd_idx = pd_idx + 1;
2056                         if (pd_idx == raid_disks-1) {
2057                                 (*dd_idx)++;    /* Q D D D P */
2058                                 qd_idx = 0;
2059                         } else if (*dd_idx >= pd_idx)
2060                                 (*dd_idx) += 2; /* D D P Q D */
2061                         break;
2062                 case ALGORITHM_RIGHT_ASYMMETRIC:
2063                         pd_idx = sector_div(stripe2, raid_disks);
2064                         qd_idx = pd_idx + 1;
2065                         if (pd_idx == raid_disks-1) {
2066                                 (*dd_idx)++;    /* Q D D D P */
2067                                 qd_idx = 0;
2068                         } else if (*dd_idx >= pd_idx)
2069                                 (*dd_idx) += 2; /* D D P Q D */
2070                         break;
2071                 case ALGORITHM_LEFT_SYMMETRIC:
2072                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2073                         qd_idx = (pd_idx + 1) % raid_disks;
2074                         *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2075                         break;
2076                 case ALGORITHM_RIGHT_SYMMETRIC:
2077                         pd_idx = sector_div(stripe2, raid_disks);
2078                         qd_idx = (pd_idx + 1) % raid_disks;
2079                         *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2080                         break;
2081
2082                 case ALGORITHM_PARITY_0:
2083                         pd_idx = 0;
2084                         qd_idx = 1;
2085                         (*dd_idx) += 2;
2086                         break;
2087                 case ALGORITHM_PARITY_N:
2088                         pd_idx = data_disks;
2089                         qd_idx = data_disks + 1;
2090                         break;
2091
2092                 case ALGORITHM_ROTATING_ZERO_RESTART:
2093                         /* Exactly the same as RIGHT_ASYMMETRIC, but or
2094                          * of blocks for computing Q is different.
2095                          */
2096                         pd_idx = sector_div(stripe2, raid_disks);
2097                         qd_idx = pd_idx + 1;
2098                         if (pd_idx == raid_disks-1) {
2099                                 (*dd_idx)++;    /* Q D D D P */
2100                                 qd_idx = 0;
2101                         } else if (*dd_idx >= pd_idx)
2102                                 (*dd_idx) += 2; /* D D P Q D */
2103                         ddf_layout = 1;
2104                         break;
2105
2106                 case ALGORITHM_ROTATING_N_RESTART:
2107                         /* Same a left_asymmetric, by first stripe is
2108                          * D D D P Q  rather than
2109                          * Q D D D P
2110                          */
2111                         stripe2 += 1;
2112                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2113                         qd_idx = pd_idx + 1;
2114                         if (pd_idx == raid_disks-1) {
2115                                 (*dd_idx)++;    /* Q D D D P */
2116                                 qd_idx = 0;
2117                         } else if (*dd_idx >= pd_idx)
2118                                 (*dd_idx) += 2; /* D D P Q D */
2119                         ddf_layout = 1;
2120                         break;
2121
2122                 case ALGORITHM_ROTATING_N_CONTINUE:
2123                         /* Same as left_symmetric but Q is before P */
2124                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2125                         qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
2126                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2127                         ddf_layout = 1;
2128                         break;
2129
2130                 case ALGORITHM_LEFT_ASYMMETRIC_6:
2131                         /* RAID5 left_asymmetric, with Q on last device */
2132                         pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2133                         if (*dd_idx >= pd_idx)
2134                                 (*dd_idx)++;
2135                         qd_idx = raid_disks - 1;
2136                         break;
2137
2138                 case ALGORITHM_RIGHT_ASYMMETRIC_6:
2139                         pd_idx = sector_div(stripe2, raid_disks-1);
2140                         if (*dd_idx >= pd_idx)
2141                                 (*dd_idx)++;
2142                         qd_idx = raid_disks - 1;
2143                         break;
2144
2145                 case ALGORITHM_LEFT_SYMMETRIC_6:
2146                         pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2147                         *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2148                         qd_idx = raid_disks - 1;
2149                         break;
2150
2151                 case ALGORITHM_RIGHT_SYMMETRIC_6:
2152                         pd_idx = sector_div(stripe2, raid_disks-1);
2153                         *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2154                         qd_idx = raid_disks - 1;
2155                         break;
2156
2157                 case ALGORITHM_PARITY_0_6:
2158                         pd_idx = 0;
2159                         (*dd_idx)++;
2160                         qd_idx = raid_disks - 1;
2161                         break;
2162
2163                 default:
2164                         BUG();
2165                 }
2166                 break;
2167         }
2168
2169         if (sh) {
2170                 sh->pd_idx = pd_idx;
2171                 sh->qd_idx = qd_idx;
2172                 sh->ddf_layout = ddf_layout;
2173         }
2174         /*
2175          * Finally, compute the new sector number
2176          */
2177         new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
2178         return new_sector;
2179 }
2180
2181
2182 static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous)
2183 {
2184         struct r5conf *conf = sh->raid_conf;
2185         int raid_disks = sh->disks;
2186         int data_disks = raid_disks - conf->max_degraded;
2187         sector_t new_sector = sh->sector, check;
2188         int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2189                                          : conf->chunk_sectors;
2190         int algorithm = previous ? conf->prev_algo
2191                                  : conf->algorithm;
2192         sector_t stripe;
2193         int chunk_offset;
2194         sector_t chunk_number;
2195         int dummy1, dd_idx = i;
2196         sector_t r_sector;
2197         struct stripe_head sh2;
2198
2199
2200         chunk_offset = sector_div(new_sector, sectors_per_chunk);
2201         stripe = new_sector;
2202
2203         if (i == sh->pd_idx)
2204                 return 0;
2205         switch(conf->level) {
2206         case 4: break;
2207         case 5:
2208                 switch (algorithm) {
2209                 case ALGORITHM_LEFT_ASYMMETRIC:
2210                 case ALGORITHM_RIGHT_ASYMMETRIC:
2211                         if (i > sh->pd_idx)
2212                                 i--;
2213                         break;
2214                 case ALGORITHM_LEFT_SYMMETRIC:
2215                 case ALGORITHM_RIGHT_SYMMETRIC:
2216                         if (i < sh->pd_idx)
2217                                 i += raid_disks;
2218                         i -= (sh->pd_idx + 1);
2219                         break;
2220                 case ALGORITHM_PARITY_0:
2221                         i -= 1;
2222                         break;
2223                 case ALGORITHM_PARITY_N:
2224                         break;
2225                 default:
2226                         BUG();
2227                 }
2228                 break;
2229         case 6:
2230                 if (i == sh->qd_idx)
2231                         return 0; /* It is the Q disk */
2232                 switch (algorithm) {
2233                 case ALGORITHM_LEFT_ASYMMETRIC:
2234                 case ALGORITHM_RIGHT_ASYMMETRIC:
2235                 case ALGORITHM_ROTATING_ZERO_RESTART:
2236                 case ALGORITHM_ROTATING_N_RESTART:
2237                         if (sh->pd_idx == raid_disks-1)
2238                                 i--;    /* Q D D D P */
2239                         else if (i > sh->pd_idx)
2240                                 i -= 2; /* D D P Q D */
2241                         break;
2242                 case ALGORITHM_LEFT_SYMMETRIC:
2243                 case ALGORITHM_RIGHT_SYMMETRIC:
2244                         if (sh->pd_idx == raid_disks-1)
2245                                 i--; /* Q D D D P */
2246                         else {
2247                                 /* D D P Q D */
2248                                 if (i < sh->pd_idx)
2249                                         i += raid_disks;
2250                                 i -= (sh->pd_idx + 2);
2251                         }
2252                         break;
2253                 case ALGORITHM_PARITY_0:
2254                         i -= 2;
2255                         break;
2256                 case ALGORITHM_PARITY_N:
2257                         break;
2258                 case ALGORITHM_ROTATING_N_CONTINUE:
2259                         /* Like left_symmetric, but P is before Q */
2260                         if (sh->pd_idx == 0)
2261                                 i--;    /* P D D D Q */
2262                         else {
2263                                 /* D D Q P D */
2264                                 if (i < sh->pd_idx)
2265                                         i += raid_disks;
2266                                 i -= (sh->pd_idx + 1);
2267                         }
2268                         break;
2269                 case ALGORITHM_LEFT_ASYMMETRIC_6:
2270                 case ALGORITHM_RIGHT_ASYMMETRIC_6:
2271                         if (i > sh->pd_idx)
2272                                 i--;
2273                         break;
2274                 case ALGORITHM_LEFT_SYMMETRIC_6:
2275                 case ALGORITHM_RIGHT_SYMMETRIC_6:
2276                         if (i < sh->pd_idx)
2277                                 i += data_disks + 1;
2278                         i -= (sh->pd_idx + 1);
2279                         break;
2280                 case ALGORITHM_PARITY_0_6:
2281                         i -= 1;
2282                         break;
2283                 default:
2284                         BUG();
2285                 }
2286                 break;
2287         }
2288
2289         chunk_number = stripe * data_disks + i;
2290         r_sector = chunk_number * sectors_per_chunk + chunk_offset;
2291
2292         check = raid5_compute_sector(conf, r_sector,
2293                                      previous, &dummy1, &sh2);
2294         if (check != sh->sector || dummy1 != dd_idx || sh2.pd_idx != sh->pd_idx
2295                 || sh2.qd_idx != sh->qd_idx) {
2296                 printk(KERN_ERR "md/raid:%s: compute_blocknr: map not correct\n",
2297                        mdname(conf->mddev));
2298                 return 0;
2299         }
2300         return r_sector;
2301 }
2302
2303
2304 static void
2305 schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
2306                          int rcw, int expand)
2307 {
2308         int i, pd_idx = sh->pd_idx, disks = sh->disks;
2309         struct r5conf *conf = sh->raid_conf;
2310         int level = conf->level;
2311
2312         if (rcw) {
2313
2314                 for (i = disks; i--; ) {
2315                         struct r5dev *dev = &sh->dev[i];
2316
2317                         if (dev->towrite) {
2318                                 set_bit(R5_LOCKED, &dev->flags);
2319                                 set_bit(R5_Wantdrain, &dev->flags);
2320                                 if (!expand)
2321                                         clear_bit(R5_UPTODATE, &dev->flags);
2322                                 s->locked++;
2323                         }
2324                 }
2325                 /* if we are not expanding this is a proper write request, and
2326                  * there will be bios with new data to be drained into the
2327                  * stripe cache
2328                  */
2329                 if (!expand) {
2330                         if (!s->locked)
2331                                 /* False alarm, nothing to do */
2332                                 return;
2333                         sh->reconstruct_state = reconstruct_state_drain_run;
2334                         set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2335                 } else
2336                         sh->reconstruct_state = reconstruct_state_run;
2337
2338                 set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2339
2340                 if (s->locked + conf->max_degraded == disks)
2341                         if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
2342                                 atomic_inc(&conf->pending_full_writes);
2343         } else {
2344                 BUG_ON(level == 6);
2345                 BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
2346                         test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
2347
2348                 for (i = disks; i--; ) {
2349                         struct r5dev *dev = &sh->dev[i];
2350                         if (i == pd_idx)
2351                                 continue;
2352
2353                         if (dev->towrite &&
2354                             (test_bit(R5_UPTODATE, &dev->flags) ||
2355                              test_bit(R5_Wantcompute, &dev->flags))) {
2356                                 set_bit(R5_Wantdrain, &dev->flags);
2357                                 set_bit(R5_LOCKED, &dev->flags);
2358                                 clear_bit(R5_UPTODATE, &dev->flags);
2359                                 s->locked++;
2360                         }
2361                 }
2362                 if (!s->locked)
2363                         /* False alarm - nothing to do */
2364                         return;
2365                 sh->reconstruct_state = reconstruct_state_prexor_drain_run;
2366                 set_bit(STRIPE_OP_PREXOR, &s->ops_request);
2367                 set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2368                 set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2369         }
2370
2371         /* keep the parity disk(s) locked while asynchronous operations
2372          * are in flight
2373          */
2374         set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
2375         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
2376         s->locked++;
2377
2378         if (level == 6) {
2379                 int qd_idx = sh->qd_idx;
2380                 struct r5dev *dev = &sh->dev[qd_idx];
2381
2382                 set_bit(R5_LOCKED, &dev->flags);
2383                 clear_bit(R5_UPTODATE, &dev->flags);
2384                 s->locked++;
2385         }
2386
2387         pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
2388                 __func__, (unsigned long long)sh->sector,
2389                 s->locked, s->ops_request);
2390 }
2391
2392 /*
2393  * Each stripe/dev can have one or more bion attached.
2394  * toread/towrite point to the first in a chain.
2395  * The bi_next chain must be in order.
2396  */
2397 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
2398 {
2399         struct bio **bip;
2400         struct r5conf *conf = sh->raid_conf;
2401         int firstwrite=0;
2402
2403         pr_debug("adding bi b#%llu to stripe s#%llu\n",
2404                 (unsigned long long)bi->bi_sector,
2405                 (unsigned long long)sh->sector);
2406
2407         /*
2408          * If several bio share a stripe. The bio bi_phys_segments acts as a
2409          * reference count to avoid race. The reference count should already be
2410          * increased before this function is called (for example, in
2411          * make_request()), so other bio sharing this stripe will not free the
2412          * stripe. If a stripe is owned by one stripe, the stripe lock will
2413          * protect it.
2414          */
2415         spin_lock_irq(&sh->stripe_lock);
2416         if (forwrite) {
2417                 bip = &sh->dev[dd_idx].towrite;
2418                 if (*bip == NULL)
2419                         firstwrite = 1;
2420         } else
2421                 bip = &sh->dev[dd_idx].toread;
2422         while (*bip && (*bip)->bi_sector < bi->bi_sector) {
2423                 if (bio_end_sector(*bip) > bi->bi_sector)
2424                         goto overlap;
2425                 bip = & (*bip)->bi_next;
2426         }
2427         if (*bip && (*bip)->bi_sector < bio_end_sector(bi))
2428                 goto overlap;
2429
2430         BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
2431         if (*bip)
2432                 bi->bi_next = *bip;
2433         *bip = bi;
2434         raid5_inc_bi_active_stripes(bi);
2435
2436         if (forwrite) {
2437                 /* check if page is covered */
2438                 sector_t sector = sh->dev[dd_idx].sector;
2439                 for (bi=sh->dev[dd_idx].towrite;
2440                      sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
2441                              bi && bi->bi_sector <= sector;
2442                      bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
2443                         if (bio_end_sector(bi) >= sector)
2444                                 sector = bio_end_sector(bi);
2445                 }
2446                 if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
2447                         set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
2448         }
2449
2450         pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
2451                 (unsigned long long)(*bip)->bi_sector,
2452                 (unsigned long long)sh->sector, dd_idx);
2453         spin_unlock_irq(&sh->stripe_lock);
2454
2455         if (conf->mddev->bitmap && firstwrite) {
2456                 bitmap_startwrite(conf->mddev->bitmap, sh->sector,
2457                                   STRIPE_SECTORS, 0);
2458                 sh->bm_seq = conf->seq_flush+1;
2459                 set_bit(STRIPE_BIT_DELAY, &sh->state);
2460         }
2461         return 1;
2462
2463  overlap:
2464         set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
2465         spin_unlock_irq(&sh->stripe_lock);
2466         return 0;
2467 }
2468
2469 static void end_reshape(struct r5conf *conf);
2470
2471 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
2472                             struct stripe_head *sh)
2473 {
2474         int sectors_per_chunk =
2475                 previous ? conf->prev_chunk_sectors : conf->chunk_sectors;
2476         int dd_idx;
2477         int chunk_offset = sector_div(stripe, sectors_per_chunk);
2478         int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
2479
2480         raid5_compute_sector(conf,
2481                              stripe * (disks - conf->max_degraded)
2482                              *sectors_per_chunk + chunk_offset,
2483                              previous,
2484                              &dd_idx, sh);
2485 }
2486
2487 static void
2488 handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
2489                                 struct stripe_head_state *s, int disks,
2490                                 struct bio **return_bi)
2491 {
2492         int i;
2493         for (i = disks; i--; ) {
2494                 struct bio *bi;
2495                 int bitmap_end = 0;
2496
2497                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2498                         struct md_rdev *rdev;
2499                         rcu_read_lock();
2500                         rdev = rcu_dereference(conf->disks[i].rdev);
2501                         if (rdev && test_bit(In_sync, &rdev->flags))
2502                                 atomic_inc(&rdev->nr_pending);
2503                         else
2504                                 rdev = NULL;
2505                         rcu_read_unlock();
2506                         if (rdev) {
2507                                 if (!rdev_set_badblocks(
2508                                             rdev,
2509                                             sh->sector,
2510                                             STRIPE_SECTORS, 0))
2511                                         md_error(conf->mddev, rdev);
2512                                 rdev_dec_pending(rdev, conf->mddev);
2513                         }
2514                 }
2515                 spin_lock_irq(&sh->stripe_lock);
2516                 /* fail all writes first */
2517                 bi = sh->dev[i].towrite;
2518                 sh->dev[i].towrite = NULL;
2519                 spin_unlock_irq(&sh->stripe_lock);
2520                 if (bi)
2521                         bitmap_end = 1;
2522
2523                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2524                         wake_up(&conf->wait_for_overlap);
2525
2526                 while (bi && bi->bi_sector <
2527                         sh->dev[i].sector + STRIPE_SECTORS) {
2528                         struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
2529                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
2530                         if (!raid5_dec_bi_active_stripes(bi)) {
2531                                 md_write_end(conf->mddev);
2532                                 bi->bi_next = *return_bi;
2533                                 *return_bi = bi;
2534                         }
2535                         bi = nextbi;
2536                 }
2537                 if (bitmap_end)
2538                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2539                                 STRIPE_SECTORS, 0, 0);
2540                 bitmap_end = 0;
2541                 /* and fail all 'written' */
2542                 bi = sh->dev[i].written;
2543                 sh->dev[i].written = NULL;
2544                 if (bi) bitmap_end = 1;
2545                 while (bi && bi->bi_sector <
2546                        sh->dev[i].sector + STRIPE_SECTORS) {
2547                         struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
2548                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
2549                         if (!raid5_dec_bi_active_stripes(bi)) {
2550                                 md_write_end(conf->mddev);
2551                                 bi->bi_next = *return_bi;
2552                                 *return_bi = bi;
2553                         }
2554                         bi = bi2;
2555                 }
2556
2557                 /* fail any reads if this device is non-operational and
2558                  * the data has not reached the cache yet.
2559                  */
2560                 if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
2561                     (!test_bit(R5_Insync, &sh->dev[i].flags) ||
2562                       test_bit(R5_ReadError, &sh->dev[i].flags))) {
2563                         spin_lock_irq(&sh->stripe_lock);
2564                         bi = sh->dev[i].toread;
2565                         sh->dev[i].toread = NULL;
2566                         spin_unlock_irq(&sh->stripe_lock);
2567                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2568                                 wake_up(&conf->wait_for_overlap);
2569                         while (bi && bi->bi_sector <
2570                                sh->dev[i].sector + STRIPE_SECTORS) {
2571                                 struct bio *nextbi =
2572                                         r5_next_bio(bi, sh->dev[i].sector);
2573                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
2574                                 if (!raid5_dec_bi_active_stripes(bi)) {
2575                                         bi->bi_next = *return_bi;
2576                                         *return_bi = bi;
2577                                 }
2578                                 bi = nextbi;
2579                         }
2580                 }
2581                 if (bitmap_end)
2582                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2583                                         STRIPE_SECTORS, 0, 0);
2584                 /* If we were in the middle of a write the parity block might
2585                  * still be locked - so just clear all R5_LOCKED flags
2586                  */
2587                 clear_bit(R5_LOCKED, &sh->dev[i].flags);
2588         }
2589
2590         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2591                 if (atomic_dec_and_test(&conf->pending_full_writes))
2592                         md_wakeup_thread(conf->mddev->thread);
2593 }
2594
2595 static void
2596 handle_failed_sync(struct r5conf *conf, struct stripe_head *sh,
2597                    struct stripe_head_state *s)
2598 {
2599         int abort = 0;
2600         int i;
2601
2602         clear_bit(STRIPE_SYNCING, &sh->state);
2603         if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
2604                 wake_up(&conf->wait_for_overlap);
2605         s->syncing = 0;
2606         s->replacing = 0;
2607         /* There is nothing more to do for sync/check/repair.
2608          * Don't even need to abort as that is handled elsewhere
2609          * if needed, and not always wanted e.g. if there is a known
2610          * bad block here.
2611          * For recover/replace we need to record a bad block on all
2612          * non-sync devices, or abort the recovery
2613          */
2614         if (test_bit(MD_RECOVERY_RECOVER, &conf->mddev->recovery)) {
2615                 /* During recovery devices cannot be removed, so
2616                  * locking and refcounting of rdevs is not needed
2617                  */
2618                 for (i = 0; i < conf->raid_disks; i++) {
2619                         struct md_rdev *rdev = conf->disks[i].rdev;
2620                         if (rdev
2621                             && !test_bit(Faulty, &rdev->flags)
2622                             && !test_bit(In_sync, &rdev->flags)
2623                             && !rdev_set_badblocks(rdev, sh->sector,
2624                                                    STRIPE_SECTORS, 0))
2625                                 abort = 1;
2626                         rdev = conf->disks[i].replacement;
2627                         if (rdev
2628                             && !test_bit(Faulty, &rdev->flags)
2629                             && !test_bit(In_sync, &rdev->flags)
2630                             && !rdev_set_badblocks(rdev, sh->sector,
2631                                                    STRIPE_SECTORS, 0))
2632                                 abort = 1;
2633                 }
2634                 if (abort)
2635                         conf->recovery_disabled =
2636                                 conf->mddev->recovery_disabled;
2637         }
2638         md_done_sync(conf->mddev, STRIPE_SECTORS, !abort);
2639 }
2640
2641 static int want_replace(struct stripe_head *sh, int disk_idx)
2642 {
2643         struct md_rdev *rdev;
2644         int rv = 0;
2645         /* Doing recovery so rcu locking not required */
2646         rdev = sh->raid_conf->disks[disk_idx].replacement;
2647         if (rdev
2648             && !test_bit(Faulty, &rdev->flags)
2649             && !test_bit(In_sync, &rdev->flags)
2650             && (rdev->recovery_offset <= sh->sector
2651                 || rdev->mddev->recovery_cp <= sh->sector))
2652                 rv = 1;
2653
2654         return rv;
2655 }
2656
2657 /* fetch_block - checks the given member device to see if its data needs
2658  * to be read or computed to satisfy a request.
2659  *
2660  * Returns 1 when no more member devices need to be checked, otherwise returns
2661  * 0 to tell the loop in handle_stripe_fill to continue
2662  */
2663 static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
2664                        int disk_idx, int disks)
2665 {
2666         struct r5dev *dev = &sh->dev[disk_idx];
2667         struct r5dev *fdev[2] = { &sh->dev[s->failed_num[0]],
2668                                   &sh->dev[s->failed_num[1]] };
2669
2670         /* is the data in this block needed, and can we get it? */
2671         if (!test_bit(R5_LOCKED, &dev->flags) &&
2672             !test_bit(R5_UPTODATE, &dev->flags) &&
2673             (dev->toread ||
2674              (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
2675              s->syncing || s->expanding ||
2676              (s->replacing && want_replace(sh, disk_idx)) ||
2677              (s->failed >= 1 && fdev[0]->toread) ||
2678              (s->failed >= 2 && fdev[1]->toread) ||
2679              (sh->raid_conf->level <= 5 && s->failed && fdev[0]->towrite &&
2680               !test_bit(R5_OVERWRITE, &fdev[0]->flags)) ||
2681              ((sh->raid_conf->level == 6 || sh->sector >= sh->raid_conf->mddev->recovery_cp)
2682               && s->failed && s->to_write))) {
2683                 /* we would like to get this block, possibly by computing it,
2684                  * otherwise read it if the backing disk is insync
2685                  */
2686                 BUG_ON(test_bit(R5_Wantcompute, &dev->flags));
2687                 BUG_ON(test_bit(R5_Wantread, &dev->flags));
2688                 if ((s->uptodate == disks - 1) &&
2689                     (s->failed && (disk_idx == s->failed_num[0] ||
2690                                    disk_idx == s->failed_num[1]))) {
2691                         /* have disk failed, and we're requested to fetch it;
2692                          * do compute it
2693                          */
2694                         pr_debug("Computing stripe %llu block %d\n",
2695                                (unsigned long long)sh->sector, disk_idx);
2696                         set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2697                         set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2698                         set_bit(R5_Wantcompute, &dev->flags);
2699                         sh->ops.target = disk_idx;
2700                         sh->ops.target2 = -1; /* no 2nd target */
2701                         s->req_compute = 1;
2702                         /* Careful: from this point on 'uptodate' is in the eye
2703                          * of raid_run_ops which services 'compute' operations
2704                          * before writes. R5_Wantcompute flags a block that will
2705                          * be R5_UPTODATE by the time it is needed for a
2706                          * subsequent operation.
2707                          */
2708                         s->uptodate++;
2709                         return 1;
2710                 } else if (s->uptodate == disks-2 && s->failed >= 2) {
2711                         /* Computing 2-failure is *very* expensive; only
2712                          * do it if failed >= 2
2713                          */
2714                         int other;
2715                         for (other = disks; other--; ) {
2716                                 if (other == disk_idx)
2717                                         continue;
2718                                 if (!test_bit(R5_UPTODATE,
2719                                       &sh->dev[other].flags))
2720                                         break;
2721                         }
2722                         BUG_ON(other < 0);
2723                         pr_debug("Computing stripe %llu blocks %d,%d\n",
2724                                (unsigned long long)sh->sector,
2725                                disk_idx, other);
2726                         set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2727                         set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2728                         set_bit(R5_Wantcompute, &sh->dev[disk_idx].flags);
2729                         set_bit(R5_Wantcompute, &sh->dev[other].flags);
2730                         sh->ops.target = disk_idx;
2731                         sh->ops.target2 = other;
2732                         s->uptodate += 2;
2733                         s->req_compute = 1;
2734                         return 1;
2735                 } else if (test_bit(R5_Insync, &dev->flags)) {
2736                         set_bit(R5_LOCKED, &dev->flags);
2737                         set_bit(R5_Wantread, &dev->flags);
2738                         s->locked++;
2739                         pr_debug("Reading block %d (sync=%d)\n",
2740                                 disk_idx, s->syncing);
2741                 }
2742         }
2743
2744         return 0;
2745 }
2746
2747 /**
2748  * handle_stripe_fill - read or compute data to satisfy pending requests.
2749  */
2750 static void handle_stripe_fill(struct stripe_head *sh,
2751                                struct stripe_head_state *s,
2752                                int disks)
2753 {
2754         int i;
2755
2756         /* look for blocks to read/compute, skip this if a compute
2757          * is already in flight, or if the stripe contents are in the
2758          * midst of changing due to a write
2759          */
2760         if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
2761             !sh->reconstruct_state)
2762                 for (i = disks; i--; )
2763                         if (fetch_block(sh, s, i, disks))
2764                                 break;
2765         set_bit(STRIPE_HANDLE, &sh->state);
2766 }
2767
2768
2769 /* handle_stripe_clean_event
2770  * any written block on an uptodate or failed drive can be returned.
2771  * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
2772  * never LOCKED, so we don't need to test 'failed' directly.
2773  */
2774 static void handle_stripe_clean_event(struct r5conf *conf,
2775         struct stripe_head *sh, int disks, struct bio **return_bi)
2776 {
2777         int i;
2778         struct r5dev *dev;
2779         int discard_pending = 0;
2780
2781         for (i = disks; i--; )
2782                 if (sh->dev[i].written) {
2783                         dev = &sh->dev[i];
2784                         if (!test_bit(R5_LOCKED, &dev->flags) &&
2785                             (test_bit(R5_UPTODATE, &dev->flags) ||
2786                              test_bit(R5_Discard, &dev->flags))) {
2787                                 /* We can return any write requests */
2788                                 struct bio *wbi, *wbi2;
2789                                 pr_debug("Return write for disc %d\n", i);
2790                                 if (test_and_clear_bit(R5_Discard, &dev->flags))
2791                                         clear_bit(R5_UPTODATE, &dev->flags);
2792                                 wbi = dev->written;
2793                                 dev->written = NULL;
2794                                 while (wbi && wbi->bi_sector <
2795                                         dev->sector + STRIPE_SECTORS) {
2796                                         wbi2 = r5_next_bio(wbi, dev->sector);
2797                                         if (!raid5_dec_bi_active_stripes(wbi)) {
2798                                                 md_write_end(conf->mddev);
2799                                                 wbi->bi_next = *return_bi;
2800                                                 *return_bi = wbi;
2801                                         }
2802                                         wbi = wbi2;
2803                                 }
2804                                 bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2805                                                 STRIPE_SECTORS,
2806                                          !test_bit(STRIPE_DEGRADED, &sh->state),
2807                                                 0);
2808                         } else if (test_bit(R5_Discard, &dev->flags))
2809                                 discard_pending = 1;
2810                 }
2811         if (!discard_pending &&
2812             test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
2813                 clear_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
2814                 clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
2815                 if (sh->qd_idx >= 0) {
2816                         clear_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
2817                         clear_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags);
2818                 }
2819                 /* now that discard is done we can proceed with any sync */
2820                 clear_bit(STRIPE_DISCARD, &sh->state);
2821                 /*
2822                  * SCSI discard will change some bio fields and the stripe has
2823                  * no updated data, so remove it from hash list and the stripe
2824                  * will be reinitialized
2825                  */
2826                 spin_lock_irq(&conf->device_lock);
2827                 remove_hash(sh);
2828                 spin_unlock_irq(&conf->device_lock);
2829                 if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state))
2830                         set_bit(STRIPE_HANDLE, &sh->state);
2831
2832         }
2833
2834         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2835                 if (atomic_dec_and_test(&conf->pending_full_writes))
2836                         md_wakeup_thread(conf->mddev->thread);
2837 }
2838
2839 static void handle_stripe_dirtying(struct r5conf *conf,
2840                                    struct stripe_head *sh,
2841                                    struct stripe_head_state *s,
2842                                    int disks)
2843 {
2844         int rmw = 0, rcw = 0, i;
2845         sector_t recovery_cp = conf->mddev->recovery_cp;
2846
2847         /* RAID6 requires 'rcw' in current implementation.
2848          * Otherwise, check whether resync is now happening or should start.
2849          * If yes, then the array is dirty (after unclean shutdown or
2850          * initial creation), so parity in some stripes might be inconsistent.
2851          * In this case, we need to always do reconstruct-write, to ensure
2852          * that in case of drive failure or read-error correction, we
2853          * generate correct data from the parity.
2854          */
2855         if (conf->max_degraded == 2 ||
2856             (recovery_cp < MaxSector && sh->sector >= recovery_cp &&
2857              s->failed == 0)) {
2858                 /* Calculate the real rcw later - for now make it
2859                  * look like rcw is cheaper
2860                  */
2861                 rcw = 1; rmw = 2;
2862                 pr_debug("force RCW max_degraded=%u, recovery_cp=%llu sh->sector=%llu\n",
2863                          conf->max_degraded, (unsigned long long)recovery_cp,
2864                          (unsigned long long)sh->sector);
2865         } else for (i = disks; i--; ) {
2866                 /* would I have to read this buffer for read_modify_write */
2867                 struct r5dev *dev = &sh->dev[i];
2868                 if ((dev->towrite || i == sh->pd_idx) &&
2869                     !test_bit(R5_LOCKED, &dev->flags) &&
2870                     !(test_bit(R5_UPTODATE, &dev->flags) ||
2871                       test_bit(R5_Wantcompute, &dev->flags))) {
2872                         if (test_bit(R5_Insync, &dev->flags))
2873                                 rmw++;
2874                         else
2875                                 rmw += 2*disks;  /* cannot read it */
2876                 }
2877                 /* Would I have to read this buffer for reconstruct_write */
2878                 if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
2879                     !test_bit(R5_LOCKED, &dev->flags) &&
2880                     !(test_bit(R5_UPTODATE, &dev->flags) ||
2881                     test_bit(R5_Wantcompute, &dev->flags))) {
2882                         if (test_bit(R5_Insync, &dev->flags)) rcw++;
2883                         else
2884                                 rcw += 2*disks;
2885                 }
2886         }
2887         pr_debug("for sector %llu, rmw=%d rcw=%d\n",
2888                 (unsigned long long)sh->sector, rmw, rcw);
2889         set_bit(STRIPE_HANDLE, &sh->state);
2890         if (rmw < rcw && rmw > 0) {
2891                 /* prefer read-modify-write, but need to get some data */
2892                 if (conf->mddev->queue)
2893                         blk_add_trace_msg(conf->mddev->queue,
2894                                           "raid5 rmw %llu %d",
2895                                           (unsigned long long)sh->sector, rmw);
2896                 for (i = disks; i--; ) {
2897                         struct r5dev *dev = &sh->dev[i];
2898                         if ((dev->towrite || i == sh->pd_idx) &&
2899                             !test_bit(R5_LOCKED, &dev->flags) &&
2900                             !(test_bit(R5_UPTODATE, &dev->flags) ||
2901                             test_bit(R5_Wantcompute, &dev->flags)) &&
2902                             test_bit(R5_Insync, &dev->flags)) {
2903                                 if (
2904                                   test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2905                                         pr_debug("Read_old block "
2906                                                  "%d for r-m-w\n", i);
2907                                         set_bit(R5_LOCKED, &dev->flags);
2908                                         set_bit(R5_Wantread, &dev->flags);
2909                                         s->locked++;
2910                                 } else {
2911                                         set_bit(STRIPE_DELAYED, &sh->state);
2912                                         set_bit(STRIPE_HANDLE, &sh->state);
2913                                 }
2914                         }
2915                 }
2916         }
2917         if (rcw <= rmw && rcw > 0) {
2918                 /* want reconstruct write, but need to get some data */
2919                 int qread =0;
2920                 rcw = 0;
2921                 for (i = disks; i--; ) {
2922                         struct r5dev *dev = &sh->dev[i];
2923                         if (!test_bit(R5_OVERWRITE, &dev->flags) &&
2924                             i != sh->pd_idx && i != sh->qd_idx &&
2925                             !test_bit(R5_LOCKED, &dev->flags) &&
2926                             !(test_bit(R5_UPTODATE, &dev->flags) ||
2927                               test_bit(R5_Wantcompute, &dev->flags))) {
2928                                 rcw++;
2929                                 if (!test_bit(R5_Insync, &dev->flags))
2930                                         continue; /* it's a failed drive */
2931                                 if (
2932                                   test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2933                                         pr_debug("Read_old block "
2934                                                 "%d for Reconstruct\n", i);
2935                                         set_bit(R5_LOCKED, &dev->flags);
2936                                         set_bit(R5_Wantread, &dev->flags);
2937                                         s->locked++;
2938                                         qread++;
2939                                 } else {
2940                                         set_bit(STRIPE_DELAYED, &sh->state);
2941                                         set_bit(STRIPE_HANDLE, &sh->state);
2942                                 }
2943                         }
2944                 }
2945                 if (rcw && conf->mddev->queue)
2946                         blk_add_trace_msg(conf->mddev->queue, "raid5 rcw %llu %d %d %d",
2947                                           (unsigned long long)sh->sector,
2948                                           rcw, qread, test_bit(STRIPE_DELAYED, &sh->state));
2949         }
2950         /* now if nothing is locked, and if we have enough data,
2951          * we can start a write request
2952          */
2953         /* since handle_stripe can be called at any time we need to handle the
2954          * case where a compute block operation has been submitted and then a
2955          * subsequent call wants to start a write request.  raid_run_ops only
2956          * handles the case where compute block and reconstruct are requested
2957          * simultaneously.  If this is not the case then new writes need to be
2958          * held off until the compute completes.
2959          */
2960         if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
2961             (s->locked == 0 && (rcw == 0 || rmw == 0) &&
2962             !test_bit(STRIPE_BIT_DELAY, &sh->state)))
2963                 schedule_reconstruction(sh, s, rcw == 0, 0);
2964 }
2965
2966 static void handle_parity_checks5(struct r5conf *conf, struct stripe_head *sh,
2967                                 struct stripe_head_state *s, int disks)
2968 {
2969         struct r5dev *dev = NULL;
2970
2971         set_bit(STRIPE_HANDLE, &sh->state);
2972
2973         switch (sh->check_state) {
2974         case check_state_idle:
2975                 /* start a new check operation if there are no failures */
2976                 if (s->failed == 0) {
2977                         BUG_ON(s->uptodate != disks);
2978                         sh->check_state = check_state_run;
2979                         set_bit(STRIPE_OP_CHECK, &s->ops_request);
2980                         clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
2981                         s->uptodate--;
2982                         break;
2983                 }
2984                 dev = &sh->dev[s->failed_num[0]];
2985                 /* fall through */
2986         case check_state_compute_result:
2987                 sh->check_state = check_state_idle;
2988                 if (!dev)
2989                         dev = &sh->dev[sh->pd_idx];
2990
2991                 /* check that a write has not made the stripe insync */
2992                 if (test_bit(STRIPE_INSYNC, &sh->state))
2993                         break;
2994
2995                 /* either failed parity check, or recovery is happening */
2996                 BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
2997                 BUG_ON(s->uptodate != disks);
2998
2999                 set_bit(R5_LOCKED, &dev->flags);
3000                 s->locked++;
3001                 set_bit(R5_Wantwrite, &dev->flags);
3002
3003                 clear_bit(STRIPE_DEGRADED, &sh->state);
3004                 set_bit(STRIPE_INSYNC, &sh->state);
3005                 break;
3006         case check_state_run:
3007                 break; /* we will be called again upon completion */
3008         case check_state_check_result:
3009                 sh->check_state = check_state_idle;
3010
3011                 /* if a failure occurred during the check operation, leave
3012                  * STRIPE_INSYNC not set and let the stripe be handled again
3013                  */
3014                 if (s->failed)
3015                         break;
3016
3017                 /* handle a successful check operation, if parity is correct
3018                  * we are done.  Otherwise update the mismatch count and repair
3019                  * parity if !MD_RECOVERY_CHECK
3020                  */
3021                 if ((sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) == 0)
3022                         /* parity is correct (on disc,
3023                          * not in buffer any more)
3024                          */
3025                         set_bit(STRIPE_INSYNC, &sh->state);
3026                 else {
3027                         atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3028                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3029                                 /* don't try to repair!! */
3030                                 set_bit(STRIPE_INSYNC, &sh->state);
3031                         else {
3032                                 sh->check_state = check_state_compute_run;
3033                                 set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3034                                 set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3035                                 set_bit(R5_Wantcompute,
3036                                         &sh->dev[sh->pd_idx].flags);
3037                                 sh->ops.target = sh->pd_idx;
3038                                 sh->ops.target2 = -1;
3039                                 s->uptodate++;
3040                         }
3041                 }
3042                 break;
3043         case check_state_compute_run:
3044                 break;
3045         default:
3046                 printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
3047                        __func__, sh->check_state,
3048                        (unsigned long long) sh->sector);
3049                 BUG();
3050         }
3051 }
3052
3053
3054 static void handle_parity_checks6(struct r5conf *conf, struct stripe_head *sh,
3055                                   struct stripe_head_state *s,
3056                                   int disks)
3057 {
3058         int pd_idx = sh->pd_idx;
3059         int qd_idx = sh->qd_idx;
3060         struct r5dev *dev;
3061
3062         set_bit(STRIPE_HANDLE, &sh->state);
3063
3064         BUG_ON(s->failed > 2);
3065
3066         /* Want to check and possibly repair P and Q.
3067          * However there could be one 'failed' device, in which
3068          * case we can only check one of them, possibly using the
3069          * other to generate missing data
3070          */
3071
3072         switch (sh->check_state) {
3073         case check_state_idle:
3074                 /* start a new check operation if there are < 2 failures */
3075                 if (s->failed == s->q_failed) {
3076                         /* The only possible failed device holds Q, so it
3077                          * makes sense to check P (If anything else were failed,
3078                          * we would have used P to recreate it).
3079                          */
3080                         sh->check_state = check_state_run;
3081                 }
3082                 if (!s->q_failed && s->failed < 2) {
3083                         /* Q is not failed, and we didn't use it to generate
3084                          * anything, so it makes sense to check it
3085                          */
3086                         if (sh->check_state == check_state_run)
3087                                 sh->check_state = check_state_run_pq;
3088                         else
3089                                 sh->check_state = check_state_run_q;
3090                 }
3091
3092                 /* discard potentially stale zero_sum_result */
3093                 sh->ops.zero_sum_result = 0;
3094
3095                 if (sh->check_state == check_state_run) {
3096                         /* async_xor_zero_sum destroys the contents of P */
3097                         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
3098                         s->uptodate--;
3099                 }
3100                 if (sh->check_state >= check_state_run &&
3101                     sh->check_state <= check_state_run_pq) {
3102                         /* async_syndrome_zero_sum preserves P and Q, so
3103                          * no need to mark them !uptodate here
3104                          */
3105                         set_bit(STRIPE_OP_CHECK, &s->ops_request);
3106                         break;
3107                 }
3108
3109                 /* we have 2-disk failure */
3110                 BUG_ON(s->failed != 2);
3111                 /* fall through */
3112         case check_state_compute_result:
3113                 sh->check_state = check_state_idle;
3114
3115                 /* check that a write has not made the stripe insync */
3116                 if (test_bit(STRIPE_INSYNC, &sh->state))
3117                         break;
3118
3119                 /* now write out any block on a failed drive,
3120                  * or P or Q if they were recomputed
3121                  */
3122                 BUG_ON(s->uptodate < disks - 1); /* We don't need Q to recover */
3123                 if (s->failed == 2) {
3124                         dev = &sh->dev[s->failed_num[1]];
3125                         s->locked++;
3126                         set_bit(R5_LOCKED, &dev->flags);
3127                         set_bit(R5_Wantwrite, &dev->flags);
3128                 }
3129                 if (s->failed >= 1) {
3130                         dev = &sh->dev[s->failed_num[0]];
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_P_RESULT) {
3136                         dev = &sh->dev[pd_idx];
3137                         s->locked++;
3138                         set_bit(R5_LOCKED, &dev->flags);
3139                         set_bit(R5_Wantwrite, &dev->flags);
3140                 }
3141                 if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3142                         dev = &sh->dev[qd_idx];
3143                         s->locked++;
3144                         set_bit(R5_LOCKED, &dev->flags);
3145                         set_bit(R5_Wantwrite, &dev->flags);
3146                 }
3147                 clear_bit(STRIPE_DEGRADED, &sh->state);
3148
3149                 set_bit(STRIPE_INSYNC, &sh->state);
3150                 break;
3151         case check_state_run:
3152         case check_state_run_q:
3153         case check_state_run_pq:
3154                 break; /* we will be called again upon completion */
3155         case check_state_check_result:
3156                 sh->check_state = check_state_idle;
3157
3158                 /* handle a successful check operation, if parity is correct
3159                  * we are done.  Otherwise update the mismatch count and repair
3160                  * parity if !MD_RECOVERY_CHECK
3161                  */
3162                 if (sh->ops.zero_sum_result == 0) {
3163                         /* both parities are correct */
3164                         if (!s->failed)
3165                                 set_bit(STRIPE_INSYNC, &sh->state);
3166                         else {
3167                                 /* in contrast to the raid5 case we can validate
3168                                  * parity, but still have a failure to write
3169                                  * back
3170                                  */
3171                                 sh->check_state = check_state_compute_result;
3172                                 /* Returning at this point means that we may go
3173                                  * off and bring p and/or q uptodate again so
3174                                  * we make sure to check zero_sum_result again
3175                                  * to verify if p or q need writeback
3176                                  */
3177                         }
3178                 } else {
3179                         atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3180                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3181                                 /* don't try to repair!! */
3182                                 set_bit(STRIPE_INSYNC, &sh->state);
3183                         else {
3184                                 int *target = &sh->ops.target;
3185
3186                                 sh->ops.target = -1;
3187                                 sh->ops.target2 = -1;
3188                                 sh->check_state = check_state_compute_run;
3189                                 set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3190                                 set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3191                                 if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3192                                         set_bit(R5_Wantcompute,
3193                                                 &sh->dev[pd_idx].flags);
3194                                         *target = pd_idx;
3195                                         target = &sh->ops.target2;
3196                                         s->uptodate++;
3197                                 }
3198                                 if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3199                                         set_bit(R5_Wantcompute,
3200                                                 &sh->dev[qd_idx].flags);
3201                                         *target = qd_idx;
3202                                         s->uptodate++;
3203                                 }
3204                         }
3205                 }
3206                 break;
3207         case check_state_compute_run:
3208                 break;
3209         default:
3210                 printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
3211                        __func__, sh->check_state,
3212                        (unsigned long long) sh->sector);
3213                 BUG();
3214         }
3215 }
3216
3217 static void handle_stripe_expansion(struct r5conf *conf, struct stripe_head *sh)
3218 {
3219         int i;
3220
3221         /* We have read all the blocks in this stripe and now we need to
3222          * copy some of them into a target stripe for expand.
3223          */
3224         struct dma_async_tx_descriptor *tx = NULL;
3225         clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3226         for (i = 0; i < sh->disks; i++)
3227                 if (i != sh->pd_idx && i != sh->qd_idx) {
3228                         int dd_idx, j;
3229                         struct stripe_head *sh2;
3230                         struct async_submit_ctl submit;
3231
3232                         sector_t bn = compute_blocknr(sh, i, 1);
3233                         sector_t s = raid5_compute_sector(conf, bn, 0,
3234                                                           &dd_idx, NULL);
3235                         sh2 = get_active_stripe(conf, s, 0, 1, 1);
3236                         if (sh2 == NULL)
3237                                 /* so far only the early blocks of this stripe
3238                                  * have been requested.  When later blocks
3239                                  * get requested, we will try again
3240                                  */
3241                                 continue;
3242                         if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
3243                            test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
3244                                 /* must have already done this block */
3245                                 release_stripe(sh2);
3246                                 continue;
3247                         }
3248
3249                         /* place all the copies on one channel */
3250                         init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
3251                         tx = async_memcpy(sh2->dev[dd_idx].page,
3252                                           sh->dev[i].page, 0, 0, STRIPE_SIZE,
3253                                           &submit);
3254
3255                         set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
3256                         set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
3257                         for (j = 0; j < conf->raid_disks; j++)
3258                                 if (j != sh2->pd_idx &&
3259                                     j != sh2->qd_idx &&
3260                                     !test_bit(R5_Expanded, &sh2->dev[j].flags))
3261                                         break;
3262                         if (j == conf->raid_disks) {
3263                                 set_bit(STRIPE_EXPAND_READY, &sh2->state);
3264                                 set_bit(STRIPE_HANDLE, &sh2->state);
3265                         }
3266                         release_stripe(sh2);
3267
3268                 }
3269         /* done submitting copies, wait for them to complete */
3270         async_tx_quiesce(&tx);
3271 }
3272
3273 /*
3274  * handle_stripe - do things to a stripe.
3275  *
3276  * We lock the stripe by setting STRIPE_ACTIVE and then examine the
3277  * state of various bits to see what needs to be done.
3278  * Possible results:
3279  *    return some read requests which now have data
3280  *    return some write requests which are safely on storage
3281  *    schedule a read on some buffers
3282  *    schedule a write of some buffers
3283  *    return confirmation of parity correctness
3284  *
3285  */
3286
3287 static void analyse_stripe(struct stripe_head *sh, struct stripe_head_state *s)
3288 {
3289         struct r5conf *conf = sh->raid_conf;
3290         int disks = sh->disks;
3291         struct r5dev *dev;
3292         int i;
3293         int do_recovery = 0;
3294
3295         memset(s, 0, sizeof(*s));
3296
3297         s->expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3298         s->expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
3299         s->failed_num[0] = -1;
3300         s->failed_num[1] = -1;
3301
3302         /* Now to look around and see what can be done */
3303         rcu_read_lock();
3304         for (i=disks; i--; ) {
3305                 struct md_rdev *rdev;
3306                 sector_t first_bad;
3307                 int bad_sectors;
3308                 int is_bad = 0;
3309
3310                 dev = &sh->dev[i];
3311
3312                 pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
3313                          i, dev->flags,
3314                          dev->toread, dev->towrite, dev->written);
3315                 /* maybe we can reply to a read
3316                  *
3317                  * new wantfill requests are only permitted while
3318                  * ops_complete_biofill is guaranteed to be inactive
3319                  */
3320                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
3321                     !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
3322                         set_bit(R5_Wantfill, &dev->flags);
3323
3324                 /* now count some things */
3325                 if (test_bit(R5_LOCKED, &dev->flags))
3326                         s->locked++;
3327                 if (test_bit(R5_UPTODATE, &dev->flags))
3328                         s->uptodate++;
3329                 if (test_bit(R5_Wantcompute, &dev->flags)) {
3330                         s->compute++;
3331                         BUG_ON(s->compute > 2);
3332                 }
3333
3334                 if (test_bit(R5_Wantfill, &dev->flags))
3335                         s->to_fill++;
3336                 else if (dev->toread)
3337                         s->to_read++;
3338                 if (dev->towrite) {
3339                         s->to_write++;
3340                         if (!test_bit(R5_OVERWRITE, &dev->flags))
3341                                 s->non_overwrite++;
3342                 }
3343                 if (dev->written)
3344                         s->written++;
3345                 /* Prefer to use the replacement for reads, but only
3346                  * if it is recovered enough and has no bad blocks.
3347                  */
3348                 rdev = rcu_dereference(conf->disks[i].replacement);
3349                 if (rdev && !test_bit(Faulty, &rdev->flags) &&
3350                     rdev->recovery_offset >= sh->sector + STRIPE_SECTORS &&
3351                     !is_badblock(rdev, sh->sector, STRIPE_SECTORS,
3352                                  &first_bad, &bad_sectors))
3353                         set_bit(R5_ReadRepl, &dev->flags);
3354                 else {
3355                         if (rdev)
3356                                 set_bit(R5_NeedReplace, &dev->flags);
3357                         rdev = rcu_dereference(conf->disks[i].rdev);
3358                         clear_bit(R5_ReadRepl, &dev->flags);
3359                 }
3360                 if (rdev && test_bit(Faulty, &rdev->flags))
3361                         rdev = NULL;
3362                 if (rdev) {
3363                         is_bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
3364                                              &first_bad, &bad_sectors);
3365                         if (s->blocked_rdev == NULL
3366                             && (test_bit(Blocked, &rdev->flags)
3367                                 || is_bad < 0)) {
3368                                 if (is_bad < 0)
3369                                         set_bit(BlockedBadBlocks,
3370                                                 &rdev->flags);
3371                                 s->blocked_rdev = rdev;
3372                                 atomic_inc(&rdev->nr_pending);
3373                         }
3374                 }
3375                 clear_bit(R5_Insync, &dev->flags);
3376                 if (!rdev)
3377                         /* Not in-sync */;
3378                 else if (is_bad) {
3379                         /* also not in-sync */
3380                         if (!test_bit(WriteErrorSeen, &rdev->flags) &&
3381                             test_bit(R5_UPTODATE, &dev->flags)) {
3382                                 /* treat as in-sync, but with a read error
3383                                  * which we can now try to correct
3384                                  */
3385                                 set_bit(R5_Insync, &dev->flags);
3386                                 set_bit(R5_ReadError, &dev->flags);
3387                         }
3388                 } else if (test_bit(In_sync, &rdev->flags))
3389                         set_bit(R5_Insync, &dev->flags);
3390                 else if (sh->sector + STRIPE_SECTORS <= rdev->recovery_offset)
3391                         /* in sync if before recovery_offset */
3392                         set_bit(R5_Insync, &dev->flags);
3393                 else if (test_bit(R5_UPTODATE, &dev->flags) &&
3394                          test_bit(R5_Expanded, &dev->flags))
3395                         /* If we've reshaped into here, we assume it is Insync.
3396                          * We will shortly update recovery_offset to make
3397                          * it official.
3398                          */
3399                         set_bit(R5_Insync, &dev->flags);
3400
3401                 if (test_bit(R5_WriteError, &dev->flags)) {
3402                         /* This flag does not apply to '.replacement'
3403                          * only to .rdev, so make sure to check that*/
3404                         struct md_rdev *rdev2 = rcu_dereference(
3405                                 conf->disks[i].rdev);
3406                         if (rdev2 == rdev)
3407                                 clear_bit(R5_Insync, &dev->flags);
3408                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3409                                 s->handle_bad_blocks = 1;
3410                                 atomic_inc(&rdev2->nr_pending);
3411                         } else
3412                                 clear_bit(R5_WriteError, &dev->flags);
3413                 }
3414                 if (test_bit(R5_MadeGood, &dev->flags)) {
3415                         /* This flag does not apply to '.replacement'
3416                          * only to .rdev, so make sure to check that*/
3417                         struct md_rdev *rdev2 = rcu_dereference(
3418                                 conf->disks[i].rdev);
3419                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3420                                 s->handle_bad_blocks = 1;
3421                                 atomic_inc(&rdev2->nr_pending);
3422                         } else
3423                                 clear_bit(R5_MadeGood, &dev->flags);
3424                 }
3425                 if (test_bit(R5_MadeGoodRepl, &dev->flags)) {
3426                         struct md_rdev *rdev2 = rcu_dereference(
3427                                 conf->disks[i].replacement);
3428                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3429                                 s->handle_bad_blocks = 1;
3430                                 atomic_inc(&rdev2->nr_pending);
3431                         } else
3432                                 clear_bit(R5_MadeGoodRepl, &dev->flags);
3433                 }
3434                 if (!test_bit(R5_Insync, &dev->flags)) {
3435                         /* The ReadError flag will just be confusing now */
3436                         clear_bit(R5_ReadError, &dev->flags);
3437                         clear_bit(R5_ReWrite, &dev->flags);
3438                 }
3439                 if (test_bit(R5_ReadError, &dev->flags))
3440                         clear_bit(R5_Insync, &dev->flags);
3441                 if (!test_bit(R5_Insync, &dev->flags)) {
3442                         if (s->failed < 2)
3443                                 s->failed_num[s->failed] = i;
3444                         s->failed++;
3445                         if (rdev && !test_bit(Faulty, &rdev->flags))
3446                                 do_recovery = 1;
3447                 }
3448         }
3449         if (test_bit(STRIPE_SYNCING, &sh->state)) {
3450                 /* If there is a failed device being replaced,
3451                  *     we must be recovering.
3452                  * else if we are after recovery_cp, we must be syncing
3453                  * else if MD_RECOVERY_REQUESTED is set, we also are syncing.
3454                  * else we can only be replacing
3455                  * sync and recovery both need to read all devices, and so
3456                  * use the same flag.
3457                  */
3458                 if (do_recovery ||
3459                     sh->sector >= conf->mddev->recovery_cp ||
3460                     test_bit(MD_RECOVERY_REQUESTED, &(conf->mddev->recovery)))
3461                         s->syncing = 1;
3462                 else
3463                         s->replacing = 1;
3464         }
3465         rcu_read_unlock();
3466 }
3467
3468 static void handle_stripe(struct stripe_head *sh)
3469 {
3470         struct stripe_head_state s;
3471         struct r5conf *conf = sh->raid_conf;
3472         int i;
3473         int prexor;
3474         int disks = sh->disks;
3475         struct r5dev *pdev, *qdev;
3476
3477         clear_bit(STRIPE_HANDLE, &sh->state);
3478         if (test_and_set_bit_lock(STRIPE_ACTIVE, &sh->state)) {
3479                 /* already being handled, ensure it gets handled
3480                  * again when current action finishes */
3481                 set_bit(STRIPE_HANDLE, &sh->state);
3482                 return;
3483         }
3484
3485         if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
3486                 spin_lock(&sh->stripe_lock);
3487                 /* Cannot process 'sync' concurrently with 'discard' */
3488                 if (!test_bit(STRIPE_DISCARD, &sh->state) &&
3489                     test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
3490                         set_bit(STRIPE_SYNCING, &sh->state);
3491                         clear_bit(STRIPE_INSYNC, &sh->state);
3492                         clear_bit(STRIPE_REPLACED, &sh->state);
3493                 }
3494                 spin_unlock(&sh->stripe_lock);
3495         }
3496         clear_bit(STRIPE_DELAYED, &sh->state);
3497
3498         pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
3499                 "pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
3500                (unsigned long long)sh->sector, sh->state,
3501                atomic_read(&sh->count), sh->pd_idx, sh->qd_idx,
3502                sh->check_state, sh->reconstruct_state);
3503
3504         analyse_stripe(sh, &s);
3505
3506         if (s.handle_bad_blocks) {
3507                 set_bit(STRIPE_HANDLE, &sh->state);
3508                 goto finish;
3509         }
3510
3511         if (unlikely(s.blocked_rdev)) {
3512                 if (s.syncing || s.expanding || s.expanded ||
3513                     s.replacing || s.to_write || s.written) {
3514                         set_bit(STRIPE_HANDLE, &sh->state);
3515                         goto finish;
3516                 }
3517                 /* There is nothing for the blocked_rdev to block */
3518                 rdev_dec_pending(s.blocked_rdev, conf->mddev);
3519                 s.blocked_rdev = NULL;
3520         }
3521
3522         if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
3523                 set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
3524                 set_bit(STRIPE_BIOFILL_RUN, &sh->state);
3525         }
3526
3527         pr_debug("locked=%d uptodate=%d to_read=%d"
3528                " to_write=%d failed=%d failed_num=%d,%d\n",
3529                s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
3530                s.failed_num[0], s.failed_num[1]);
3531         /* check if the array has lost more than max_degraded devices and,
3532          * if so, some requests might need to be failed.
3533          */
3534         if (s.failed > conf->max_degraded) {
3535                 sh->check_state = 0;
3536                 sh->reconstruct_state = 0;
3537                 if (s.to_read+s.to_write+s.written)
3538                         handle_failed_stripe(conf, sh, &s, disks, &s.return_bi);
3539                 if (s.syncing + s.replacing)
3540                         handle_failed_sync(conf, sh, &s);
3541         }
3542
3543         /* Now we check to see if any write operations have recently
3544          * completed
3545          */
3546         prexor = 0;
3547         if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
3548                 prexor = 1;
3549         if (sh->reconstruct_state == reconstruct_state_drain_result ||
3550             sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
3551                 sh->reconstruct_state = reconstruct_state_idle;
3552
3553                 /* All the 'written' buffers and the parity block are ready to
3554                  * be written back to disk
3555                  */
3556                 BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags) &&
3557                        !test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags));
3558                 BUG_ON(sh->qd_idx >= 0 &&
3559                        !test_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags) &&
3560                        !test_bit(R5_Discard, &sh->dev[sh->qd_idx].flags));
3561                 for (i = disks; i--; ) {
3562                         struct r5dev *dev = &sh->dev[i];
3563                         if (test_bit(R5_LOCKED, &dev->flags) &&
3564                                 (i == sh->pd_idx || i == sh->qd_idx ||
3565                                  dev->written)) {
3566                                 pr_debug("Writing block %d\n", i);
3567                                 set_bit(R5_Wantwrite, &dev->flags);
3568                                 if (prexor)
3569                                         continue;
3570                                 if (s.failed > 1)
3571                                         continue;
3572                                 if (!test_bit(R5_Insync, &dev->flags) ||
3573                                     ((i == sh->pd_idx || i == sh->qd_idx)  &&
3574                                      s.failed == 0))
3575                                         set_bit(STRIPE_INSYNC, &sh->state);
3576                         }
3577                 }
3578                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3579                         s.dec_preread_active = 1;
3580         }
3581
3582         /*
3583          * might be able to return some write requests if the parity blocks
3584          * are safe, or on a failed drive
3585          */
3586         pdev = &sh->dev[sh->pd_idx];
3587         s.p_failed = (s.failed >= 1 && s.failed_num[0] == sh->pd_idx)
3588                 || (s.failed >= 2 && s.failed_num[1] == sh->pd_idx);
3589         qdev = &sh->dev[sh->qd_idx];
3590         s.q_failed = (s.failed >= 1 && s.failed_num[0] == sh->qd_idx)
3591                 || (s.failed >= 2 && s.failed_num[1] == sh->qd_idx)
3592                 || conf->level < 6;
3593
3594         if (s.written &&
3595             (s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
3596                              && !test_bit(R5_LOCKED, &pdev->flags)
3597                              && (test_bit(R5_UPTODATE, &pdev->flags) ||
3598                                  test_bit(R5_Discard, &pdev->flags))))) &&
3599             (s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
3600                              && !test_bit(R5_LOCKED, &qdev->flags)
3601                              && (test_bit(R5_UPTODATE, &qdev->flags) ||
3602                                  test_bit(R5_Discard, &qdev->flags))))))
3603                 handle_stripe_clean_event(conf, sh, disks, &s.return_bi);
3604
3605         /* Now we might consider reading some blocks, either to check/generate
3606          * parity, or to satisfy requests
3607          * or to load a block that is being partially written.
3608          */
3609         if (s.to_read || s.non_overwrite
3610             || (conf->level == 6 && s.to_write && s.failed)
3611             || (s.syncing && (s.uptodate + s.compute < disks))
3612             || s.replacing
3613             || s.expanding)
3614                 handle_stripe_fill(sh, &s, disks);
3615
3616         /* Now to consider new write requests and what else, if anything
3617          * should be read.  We do not handle new writes when:
3618          * 1/ A 'write' operation (copy+xor) is already in flight.
3619          * 2/ A 'check' operation is in flight, as it may clobber the parity
3620          *    block.
3621          */
3622         if (s.to_write && !sh->reconstruct_state && !sh->check_state)
3623                 handle_stripe_dirtying(conf, sh, &s, disks);
3624
3625         /* maybe we need to check and possibly fix the parity for this stripe
3626          * Any reads will already have been scheduled, so we just see if enough
3627          * data is available.  The parity check is held off while parity
3628          * dependent operations are in flight.
3629          */
3630         if (sh->check_state ||
3631             (s.syncing && s.locked == 0 &&
3632              !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
3633              !test_bit(STRIPE_INSYNC, &sh->state))) {
3634                 if (conf->level == 6)
3635                         handle_parity_checks6(conf, sh, &s, disks);
3636                 else
3637                         handle_parity_checks5(conf, sh, &s, disks);
3638         }
3639
3640         if ((s.replacing || s.syncing) && s.locked == 0
3641             && !test_bit(STRIPE_COMPUTE_RUN, &sh->state)
3642             && !test_bit(STRIPE_REPLACED, &sh->state)) {
3643                 /* Write out to replacement devices where possible */
3644                 for (i = 0; i < conf->raid_disks; i++)
3645                         if (test_bit(R5_NeedReplace, &sh->dev[i].flags)) {
3646                                 WARN_ON(!test_bit(R5_UPTODATE, &sh->dev[i].flags));
3647                                 set_bit(R5_WantReplace, &sh->dev[i].flags);
3648                                 set_bit(R5_LOCKED, &sh->dev[i].flags);
3649                                 s.locked++;
3650                         }
3651                 if (s.replacing)
3652                         set_bit(STRIPE_INSYNC, &sh->state);
3653                 set_bit(STRIPE_REPLACED, &sh->state);
3654         }
3655         if ((s.syncing || s.replacing) && s.locked == 0 &&
3656             !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
3657             test_bit(STRIPE_INSYNC, &sh->state)) {
3658                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3659                 clear_bit(STRIPE_SYNCING, &sh->state);
3660                 if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
3661                         wake_up(&conf->wait_for_overlap);
3662         }
3663
3664         /* If the failed drives are just a ReadError, then we might need
3665          * to progress the repair/check process
3666          */
3667         if (s.failed <= conf->max_degraded && !conf->mddev->ro)
3668                 for (i = 0; i < s.failed; i++) {
3669                         struct r5dev *dev = &sh->dev[s.failed_num[i]];
3670                         if (test_bit(R5_ReadError, &dev->flags)
3671                             && !test_bit(R5_LOCKED, &dev->flags)
3672                             && test_bit(R5_UPTODATE, &dev->flags)
3673                                 ) {
3674                                 if (!test_bit(R5_ReWrite, &dev->flags)) {
3675                                         set_bit(R5_Wantwrite, &dev->flags);
3676                                         set_bit(R5_ReWrite, &dev->flags);
3677                                         set_bit(R5_LOCKED, &dev->flags);
3678                                         s.locked++;
3679                                 } else {
3680                                         /* let's read it back */
3681                                         set_bit(R5_Wantread, &dev->flags);
3682                                         set_bit(R5_LOCKED, &dev->flags);
3683                                         s.locked++;
3684                                 }
3685                         }
3686                 }
3687
3688
3689         /* Finish reconstruct operations initiated by the expansion process */
3690         if (sh->reconstruct_state == reconstruct_state_result) {
3691                 struct stripe_head *sh_src
3692                         = get_active_stripe(conf, sh->sector, 1, 1, 1);
3693                 if (sh_src && test_bit(STRIPE_EXPAND_SOURCE, &sh_src->state)) {
3694                         /* sh cannot be written until sh_src has been read.
3695                          * so arrange for sh to be delayed a little
3696                          */
3697                         set_bit(STRIPE_DELAYED, &sh->state);
3698                         set_bit(STRIPE_HANDLE, &sh->state);
3699                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE,
3700                                               &sh_src->state))
3701                                 atomic_inc(&conf->preread_active_stripes);
3702                         release_stripe(sh_src);
3703                         goto finish;
3704                 }
3705                 if (sh_src)
3706                         release_stripe(sh_src);
3707
3708                 sh->reconstruct_state = reconstruct_state_idle;
3709                 clear_bit(STRIPE_EXPANDING, &sh->state);
3710                 for (i = conf->raid_disks; i--; ) {
3711                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
3712                         set_bit(R5_LOCKED, &sh->dev[i].flags);
3713                         s.locked++;
3714                 }
3715         }
3716
3717         if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
3718             !sh->reconstruct_state) {
3719                 /* Need to write out all blocks after computing parity */
3720                 sh->disks = conf->raid_disks;
3721                 stripe_set_idx(sh->sector, conf, 0, sh);
3722                 schedule_reconstruction(sh, &s, 1, 1);
3723         } else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
3724                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
3725                 atomic_dec(&conf->reshape_stripes);
3726                 wake_up(&conf->wait_for_overlap);
3727                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3728         }
3729
3730         if (s.expanding && s.locked == 0 &&
3731             !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
3732                 handle_stripe_expansion(conf, sh);
3733
3734 finish:
3735         /* wait for this device to become unblocked */
3736         if (unlikely(s.blocked_rdev)) {
3737                 if (conf->mddev->external)
3738                         md_wait_for_blocked_rdev(s.blocked_rdev,
3739                                                  conf->mddev);
3740                 else
3741                         /* Internal metadata will immediately
3742                          * be written by raid5d, so we don't
3743                          * need to wait here.
3744                          */
3745                         rdev_dec_pending(s.blocked_rdev,
3746                                          conf->mddev);
3747         }
3748
3749         if (s.handle_bad_blocks)
3750                 for (i = disks; i--; ) {
3751                         struct md_rdev *rdev;
3752                         struct r5dev *dev = &sh->dev[i];
3753                         if (test_and_clear_bit(R5_WriteError, &dev->flags)) {
3754                                 /* We own a safe reference to the rdev */
3755                                 rdev = conf->disks[i].rdev;
3756                                 if (!rdev_set_badblocks(rdev, sh->sector,
3757                                                         STRIPE_SECTORS, 0))
3758                                         md_error(conf->mddev, rdev);
3759                                 rdev_dec_pending(rdev, conf->mddev);
3760                         }
3761                         if (test_and_clear_bit(R5_MadeGood, &dev->flags)) {
3762                                 rdev = conf->disks[i].rdev;
3763                                 rdev_clear_badblocks(rdev, sh->sector,
3764                                                      STRIPE_SECTORS, 0);
3765                                 rdev_dec_pending(rdev, conf->mddev);
3766                         }
3767                         if (test_and_clear_bit(R5_MadeGoodRepl, &dev->flags)) {
3768                                 rdev = conf->disks[i].replacement;
3769                                 if (!rdev)
3770                                         /* rdev have been moved down */
3771                                         rdev = conf->disks[i].rdev;
3772                                 rdev_clear_badblocks(rdev, sh->sector,
3773                                                      STRIPE_SECTORS, 0);
3774                                 rdev_dec_pending(rdev, conf->mddev);
3775                         }
3776                 }
3777
3778         if (s.ops_request)
3779                 raid_run_ops(sh, s.ops_request);
3780
3781         ops_run_io(sh, &s);
3782
3783         if (s.dec_preread_active) {
3784                 /* We delay this until after ops_run_io so that if make_request
3785                  * is waiting on a flush, it won't continue until the writes
3786                  * have actually been submitted.
3787                  */
3788                 atomic_dec(&conf->preread_active_stripes);
3789                 if (atomic_read(&conf->preread_active_stripes) <
3790                     IO_THRESHOLD)
3791                         md_wakeup_thread(conf->mddev->thread);
3792         }
3793
3794         return_io(s.return_bi);
3795
3796         clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
3797 }
3798
3799 static void raid5_activate_delayed(struct r5conf *conf)
3800 {
3801         if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
3802                 while (!list_empty(&conf->delayed_list)) {
3803                         struct list_head *l = conf->delayed_list.next;
3804                         struct stripe_head *sh;
3805                         sh = list_entry(l, struct stripe_head, lru);
3806                         list_del_init(l);
3807                         clear_bit(STRIPE_DELAYED, &sh->state);
3808                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3809                                 atomic_inc(&conf->preread_active_stripes);
3810                         list_add_tail(&sh->lru, &conf->hold_list);
3811                 }
3812         }
3813 }
3814
3815 static void activate_bit_delay(struct r5conf *conf)
3816 {
3817         /* device_lock is held */
3818         struct list_head head;
3819         list_add(&head, &conf->bitmap_list);
3820         list_del_init(&conf->bitmap_list);
3821         while (!list_empty(&head)) {
3822                 struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
3823                 list_del_init(&sh->lru);
3824                 atomic_inc(&sh->count);
3825                 __release_stripe(conf, sh);
3826         }
3827 }
3828
3829 int md_raid5_congested(struct mddev *mddev, int bits)
3830 {
3831         struct r5conf *conf = mddev->private;
3832
3833         /* No difference between reads and writes.  Just check
3834          * how busy the stripe_cache is
3835          */
3836
3837         if (conf->inactive_blocked)
3838                 return 1;
3839         if (conf->quiesce)
3840                 return 1;
3841         if (list_empty_careful(&conf->inactive_list))
3842                 return 1;
3843
3844         return 0;
3845 }
3846 EXPORT_SYMBOL_GPL(md_raid5_congested);
3847
3848 static int raid5_congested(void *data, int bits)
3849 {
3850         struct mddev *mddev = data;
3851
3852         return mddev_congested(mddev, bits) ||
3853                 md_raid5_congested(mddev, bits);
3854 }
3855
3856 /* We want read requests to align with chunks where possible,
3857  * but write requests don't need to.
3858  */
3859 static int raid5_mergeable_bvec(struct request_queue *q,
3860                                 struct bvec_merge_data *bvm,
3861                                 struct bio_vec *biovec)
3862 {
3863         struct mddev *mddev = q->queuedata;
3864         sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
3865         int max;
3866         unsigned int chunk_sectors = mddev->chunk_sectors;
3867         unsigned int bio_sectors = bvm->bi_size >> 9;
3868
3869         if ((bvm->bi_rw & 1) == WRITE)
3870                 return biovec->bv_len; /* always allow writes to be mergeable */
3871
3872         if (mddev->new_chunk_sectors < mddev->chunk_sectors)
3873                 chunk_sectors = mddev->new_chunk_sectors;
3874         max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
3875         if (max < 0) max = 0;
3876         if (max <= biovec->bv_len && bio_sectors == 0)
3877                 return biovec->bv_len;
3878         else
3879                 return max;
3880 }
3881
3882
3883 static int in_chunk_boundary(struct mddev *mddev, struct bio *bio)
3884 {
3885         sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
3886         unsigned int chunk_sectors = mddev->chunk_sectors;
3887         unsigned int bio_sectors = bio_sectors(bio);
3888
3889         if (mddev->new_chunk_sectors < mddev->chunk_sectors)
3890                 chunk_sectors = mddev->new_chunk_sectors;
3891         return  chunk_sectors >=
3892                 ((sector & (chunk_sectors - 1)) + bio_sectors);
3893 }
3894
3895 /*
3896  *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
3897  *  later sampled by raid5d.
3898  */
3899 static void add_bio_to_retry(struct bio *bi,struct r5conf *conf)
3900 {
3901         unsigned long flags;
3902
3903         spin_lock_irqsave(&conf->device_lock, flags);
3904
3905         bi->bi_next = conf->retry_read_aligned_list;
3906         conf->retry_read_aligned_list = bi;
3907
3908         spin_unlock_irqrestore(&conf->device_lock, flags);
3909         md_wakeup_thread(conf->mddev->thread);
3910 }
3911
3912
3913 static struct bio *remove_bio_from_retry(struct r5conf *conf)
3914 {
3915         struct bio *bi;
3916
3917         bi = conf->retry_read_aligned;
3918         if (bi) {
3919                 conf->retry_read_aligned = NULL;
3920                 return bi;
3921         }
3922         bi = conf->retry_read_aligned_list;
3923         if(bi) {
3924                 conf->retry_read_aligned_list = bi->bi_next;
3925                 bi->bi_next = NULL;
3926                 /*
3927                  * this sets the active strip count to 1 and the processed
3928                  * strip count to zero (upper 8 bits)
3929                  */
3930                 raid5_set_bi_stripes(bi, 1); /* biased count of active stripes */
3931         }
3932
3933         return bi;
3934 }
3935
3936
3937 /*
3938  *  The "raid5_align_endio" should check if the read succeeded and if it
3939  *  did, call bio_endio on the original bio (having bio_put the new bio
3940  *  first).
3941  *  If the read failed..
3942  */
3943 static void raid5_align_endio(struct bio *bi, int error)
3944 {
3945         struct bio* raid_bi  = bi->bi_private;
3946         struct mddev *mddev;
3947         struct r5conf *conf;
3948         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
3949         struct md_rdev *rdev;
3950
3951         bio_put(bi);
3952
3953         rdev = (void*)raid_bi->bi_next;
3954         raid_bi->bi_next = NULL;
3955         mddev = rdev->mddev;
3956         conf = mddev->private;
3957
3958         rdev_dec_pending(rdev, conf->mddev);
3959
3960         if (!error && uptodate) {
3961                 trace_block_bio_complete(bdev_get_queue(raid_bi->bi_bdev),
3962                                          raid_bi, 0);
3963                 bio_endio(raid_bi, 0);
3964                 if (atomic_dec_and_test(&conf->active_aligned_reads))
3965                         wake_up(&conf->wait_for_stripe);
3966                 return;
3967         }
3968
3969
3970         pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
3971
3972         add_bio_to_retry(raid_bi, conf);
3973 }
3974
3975 static int bio_fits_rdev(struct bio *bi)
3976 {
3977         struct request_queue *q = bdev_get_queue(bi->bi_bdev);
3978
3979         if (bio_sectors(bi) > queue_max_sectors(q))
3980                 return 0;
3981         blk_recount_segments(q, bi);
3982         if (bi->bi_phys_segments > queue_max_segments(q))
3983                 return 0;
3984
3985         if (q->merge_bvec_fn)
3986                 /* it's too hard to apply the merge_bvec_fn at this stage,
3987                  * just just give up
3988                  */
3989                 return 0;
3990
3991         return 1;
3992 }
3993
3994
3995 static int chunk_aligned_read(struct mddev *mddev, struct bio * raid_bio)
3996 {
3997         struct r5conf *conf = mddev->private;
3998         int dd_idx;
3999         struct bio* align_bi;
4000         struct md_rdev *rdev;
4001         sector_t end_sector;
4002
4003         if (!in_chunk_boundary(mddev, raid_bio)) {
4004                 pr_debug("chunk_aligned_read : non aligned\n");
4005                 return 0;
4006         }
4007         /*
4008          * use bio_clone_mddev to make a copy of the bio
4009          */
4010         align_bi = bio_clone_mddev(raid_bio, GFP_NOIO, mddev);
4011         if (!align_bi)
4012                 return 0;
4013         /*
4014          *   set bi_end_io to a new function, and set bi_private to the
4015          *     original bio.
4016          */
4017         align_bi->bi_end_io  = raid5_align_endio;
4018         align_bi->bi_private = raid_bio;
4019         /*
4020          *      compute position
4021          */
4022         align_bi->bi_sector =  raid5_compute_sector(conf, raid_bio->bi_sector,
4023                                                     0,
4024                                                     &dd_idx, NULL);
4025
4026         end_sector = bio_end_sector(align_bi);
4027         rcu_read_lock();
4028         rdev = rcu_dereference(conf->disks[dd_idx].replacement);
4029         if (!rdev || test_bit(Faulty, &rdev->flags) ||
4030             rdev->recovery_offset < end_sector) {
4031                 rdev = rcu_dereference(conf->disks[dd_idx].rdev);
4032                 if (rdev &&
4033                     (test_bit(Faulty, &rdev->flags) ||
4034                     !(test_bit(In_sync, &rdev->flags) ||
4035                       rdev->recovery_offset >= end_sector)))
4036                         rdev = NULL;
4037         }
4038         if (rdev) {
4039                 sector_t first_bad;
4040                 int bad_sectors;
4041
4042                 atomic_inc(&rdev->nr_pending);
4043                 rcu_read_unlock();
4044                 raid_bio->bi_next = (void*)rdev;
4045                 align_bi->bi_bdev =  rdev->bdev;
4046                 align_bi->bi_flags &= ~(1 << BIO_SEG_VALID);
4047
4048                 if (!bio_fits_rdev(align_bi) ||
4049                     is_badblock(rdev, align_bi->bi_sector, bio_sectors(align_bi),
4050                                 &first_bad, &bad_sectors)) {
4051                         /* too big in some way, or has a known bad block */
4052                         bio_put(align_bi);
4053                         rdev_dec_pending(rdev, mddev);
4054                         return 0;
4055                 }
4056
4057                 /* No reshape active, so we can trust rdev->data_offset */
4058                 align_bi->bi_sector += rdev->data_offset;
4059
4060                 spin_lock_irq(&conf->device_lock);
4061                 wait_event_lock_irq(conf->wait_for_stripe,
4062                                     conf->quiesce == 0,
4063                                     conf->device_lock);
4064                 atomic_inc(&conf->active_aligned_reads);
4065                 spin_unlock_irq(&conf->device_lock);
4066
4067                 if (mddev->gendisk)
4068                         trace_block_bio_remap(bdev_get_queue(align_bi->bi_bdev),
4069                                               align_bi, disk_devt(mddev->gendisk),
4070                                               raid_bio->bi_sector);
4071                 generic_make_request(align_bi);
4072                 return 1;
4073         } else {
4074                 rcu_read_unlock();
4075                 bio_put(align_bi);
4076                 return 0;
4077         }
4078 }
4079
4080 /* __get_priority_stripe - get the next stripe to process
4081  *
4082  * Full stripe writes are allowed to pass preread active stripes up until
4083  * the bypass_threshold is exceeded.  In general the bypass_count
4084  * increments when the handle_list is handled before the hold_list; however, it
4085  * will not be incremented when STRIPE_IO_STARTED is sampled set signifying a
4086  * stripe with in flight i/o.  The bypass_count will be reset when the
4087  * head of the hold_list has changed, i.e. the head was promoted to the
4088  * handle_list.
4089  */
4090 static struct stripe_head *__get_priority_stripe(struct r5conf *conf)
4091 {
4092         struct stripe_head *sh;
4093
4094         pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
4095                   __func__,
4096                   list_empty(&conf->handle_list) ? "empty" : "busy",
4097                   list_empty(&conf->hold_list) ? "empty" : "busy",
4098                   atomic_read(&conf->pending_full_writes), conf->bypass_count);
4099
4100         if (!list_empty(&conf->handle_list)) {
4101                 sh = list_entry(conf->handle_list.next, typeof(*sh), lru);
4102
4103                 if (list_empty(&conf->hold_list))
4104                         conf->bypass_count = 0;
4105                 else if (!test_bit(STRIPE_IO_STARTED, &sh->state)) {
4106                         if (conf->hold_list.next == conf->last_hold)
4107                                 conf->bypass_count++;
4108                         else {
4109                                 conf->last_hold = conf->hold_list.next;
4110                                 conf->bypass_count -= conf->bypass_threshold;
4111                                 if (conf->bypass_count < 0)
4112                                         conf->bypass_count = 0;
4113                         }
4114                 }
4115         } else if (!list_empty(&conf->hold_list) &&
4116                    ((conf->bypass_threshold &&
4117                      conf->bypass_count > conf->bypass_threshold) ||
4118                     atomic_read(&conf->pending_full_writes) == 0)) {
4119                 sh = list_entry(conf->hold_list.next,
4120                                 typeof(*sh), lru);
4121                 conf->bypass_count -= conf->bypass_threshold;
4122                 if (conf->bypass_count < 0)
4123                         conf->bypass_count = 0;
4124         } else
4125                 return NULL;
4126
4127         list_del_init(&sh->lru);
4128         atomic_inc(&sh->count);
4129         BUG_ON(atomic_read(&sh->count) != 1);
4130         return sh;
4131 }
4132
4133 struct raid5_plug_cb {
4134         struct blk_plug_cb      cb;
4135         struct list_head        list;
4136 };
4137
4138 static void raid5_unplug(struct blk_plug_cb *blk_cb, bool from_schedule)
4139 {
4140         struct raid5_plug_cb *cb = container_of(
4141                 blk_cb, struct raid5_plug_cb, cb);
4142         struct stripe_head *sh;
4143         struct mddev *mddev = cb->cb.data;
4144         struct r5conf *conf = mddev->private;
4145         int cnt = 0;
4146
4147         if (cb->list.next && !list_empty(&cb->list)) {
4148                 spin_lock_irq(&conf->device_lock);
4149                 while (!list_empty(&cb->list)) {
4150                         sh = list_first_entry(&cb->list, struct stripe_head, lru);
4151                         list_del_init(&sh->lru);
4152                         /*
4153                          * avoid race release_stripe_plug() sees
4154                          * STRIPE_ON_UNPLUG_LIST clear but the stripe
4155                          * is still in our list
4156                          */
4157                         smp_mb__before_clear_bit();
4158                         clear_bit(STRIPE_ON_UNPLUG_LIST, &sh->state);
4159                         __release_stripe(conf, sh);
4160                         cnt++;
4161                 }
4162                 spin_unlock_irq(&conf->device_lock);
4163         }
4164         if (mddev->queue)
4165                 trace_block_unplug(mddev->queue, cnt, !from_schedule);
4166         kfree(cb);
4167 }
4168
4169 static void release_stripe_plug(struct mddev *mddev,
4170                                 struct stripe_head *sh)
4171 {
4172         struct blk_plug_cb *blk_cb = blk_check_plugged(
4173                 raid5_unplug, mddev,
4174                 sizeof(struct raid5_plug_cb));
4175         struct raid5_plug_cb *cb;
4176
4177         if (!blk_cb) {
4178                 release_stripe(sh);
4179                 return;
4180         }
4181
4182         cb = container_of(blk_cb, struct raid5_plug_cb, cb);
4183
4184         if (cb->list.next == NULL)
4185                 INIT_LIST_HEAD(&cb->list);
4186
4187         if (!test_and_set_bit(STRIPE_ON_UNPLUG_LIST, &sh->state))
4188                 list_add_tail(&sh->lru, &cb->list);
4189         else
4190                 release_stripe(sh);
4191 }
4192
4193 static void make_discard_request(struct mddev *mddev, struct bio *bi)
4194 {
4195         struct r5conf *conf = mddev->private;
4196         sector_t logical_sector, last_sector;
4197         struct stripe_head *sh;
4198         int remaining;
4199         int stripe_sectors;
4200
4201         if (mddev->reshape_position != MaxSector)
4202                 /* Skip discard while reshape is happening */
4203                 return;
4204
4205         logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4206         last_sector = bi->bi_sector + (bi->bi_size>>9);
4207
4208         bi->bi_next = NULL;
4209         bi->bi_phys_segments = 1; /* over-loaded to count active stripes */
4210
4211         stripe_sectors = conf->chunk_sectors *
4212                 (conf->raid_disks - conf->max_degraded);
4213         logical_sector = DIV_ROUND_UP_SECTOR_T(logical_sector,
4214                                                stripe_sectors);
4215         sector_div(last_sector, stripe_sectors);
4216
4217         logical_sector *= conf->chunk_sectors;
4218         last_sector *= conf->chunk_sectors;
4219
4220         for (; logical_sector < last_sector;
4221              logical_sector += STRIPE_SECTORS) {
4222                 DEFINE_WAIT(w);
4223                 int d;
4224         again:
4225                 sh = get_active_stripe(conf, logical_sector, 0, 0, 0);
4226                 prepare_to_wait(&conf->wait_for_overlap, &w,
4227                                 TASK_UNINTERRUPTIBLE);
4228                 set_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
4229                 if (test_bit(STRIPE_SYNCING, &sh->state)) {
4230                         release_stripe(sh);
4231                         schedule();
4232                         goto again;
4233                 }
4234                 clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
4235                 spin_lock_irq(&sh->stripe_lock);
4236                 for (d = 0; d < conf->raid_disks; d++) {
4237                         if (d == sh->pd_idx || d == sh->qd_idx)
4238                                 continue;
4239                         if (sh->dev[d].towrite || sh->dev[d].toread) {
4240                                 set_bit(R5_Overlap, &sh->dev[d].flags);
4241                                 spin_unlock_irq(&sh->stripe_lock);
4242                                 release_stripe(sh);
4243                                 schedule();
4244                                 goto again;
4245                         }
4246                 }
4247                 set_bit(STRIPE_DISCARD, &sh->state);
4248                 finish_wait(&conf->wait_for_overlap, &w);
4249                 for (d = 0; d < conf->raid_disks; d++) {
4250                         if (d == sh->pd_idx || d == sh->qd_idx)
4251                                 continue;
4252                         sh->dev[d].towrite = bi;
4253                         set_bit(R5_OVERWRITE, &sh->dev[d].flags);
4254                         raid5_inc_bi_active_stripes(bi);
4255                 }
4256                 spin_unlock_irq(&sh->stripe_lock);
4257                 if (conf->mddev->bitmap) {
4258                         for (d = 0;
4259                              d < conf->raid_disks - conf->max_degraded;
4260                              d++)
4261                                 bitmap_startwrite(mddev->bitmap,
4262                                                   sh->sector,
4263                                                   STRIPE_SECTORS,
4264                                                   0);
4265                         sh->bm_seq = conf->seq_flush + 1;
4266                         set_bit(STRIPE_BIT_DELAY, &sh->state);
4267                 }
4268
4269                 set_bit(STRIPE_HANDLE, &sh->state);
4270                 clear_bit(STRIPE_DELAYED, &sh->state);
4271                 if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4272                         atomic_inc(&conf->preread_active_stripes);
4273                 release_stripe_plug(mddev, sh);
4274         }
4275
4276         remaining = raid5_dec_bi_active_stripes(bi);
4277         if (remaining == 0) {
4278                 md_write_end(mddev);
4279                 bio_endio(bi, 0);
4280         }
4281 }
4282
4283 static void make_request(struct mddev *mddev, struct bio * bi)
4284 {
4285         struct r5conf *conf = mddev->private;
4286         int dd_idx;
4287         sector_t new_sector;
4288         sector_t logical_sector, last_sector;
4289         struct stripe_head *sh;
4290         const int rw = bio_data_dir(bi);
4291         int remaining;
4292
4293         if (unlikely(bi->bi_rw & REQ_FLUSH)) {
4294                 md_flush_request(mddev, bi);
4295                 return;
4296         }
4297
4298         md_write_start(mddev, bi);
4299
4300         if (rw == READ &&
4301              mddev->reshape_position == MaxSector &&
4302              chunk_aligned_read(mddev,bi))
4303                 return;
4304
4305         if (unlikely(bi->bi_rw & REQ_DISCARD)) {
4306                 make_discard_request(mddev, bi);
4307                 return;
4308         }
4309
4310         logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4311         last_sector = bio_end_sector(bi);
4312         bi->bi_next = NULL;
4313         bi->bi_phys_segments = 1;       /* over-loaded to count active stripes */
4314
4315         for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
4316                 DEFINE_WAIT(w);
4317                 int previous;
4318
4319         retry:
4320                 previous = 0;
4321                 prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
4322                 if (unlikely(conf->reshape_progress != MaxSector)) {
4323                         /* spinlock is needed as reshape_progress may be
4324                          * 64bit on a 32bit platform, and so it might be
4325                          * possible to see a half-updated value
4326                          * Of course reshape_progress could change after
4327                          * the lock is dropped, so once we get a reference
4328                          * to the stripe that we think it is, we will have
4329                          * to check again.
4330                          */
4331                         spin_lock_irq(&conf->device_lock);
4332                         if (mddev->reshape_backwards
4333                             ? logical_sector < conf->reshape_progress
4334                             : logical_sector >= conf->reshape_progress) {
4335                                 previous = 1;
4336                         } else {
4337                                 if (mddev->reshape_backwards
4338                                     ? logical_sector < conf->reshape_safe
4339                                     : logical_sector >= conf->reshape_safe) {
4340                                         spin_unlock_irq(&conf->device_lock);
4341                                         schedule();
4342                                         goto retry;
4343                                 }
4344                         }
4345                         spin_unlock_irq(&conf->device_lock);
4346                 }
4347
4348                 new_sector = raid5_compute_sector(conf, logical_sector,
4349                                                   previous,
4350                                                   &dd_idx, NULL);
4351                 pr_debug("raid456: make_request, sector %llu logical %llu\n",
4352                         (unsigned long long)new_sector,
4353                         (unsigned long long)logical_sector);
4354
4355                 sh = get_active_stripe(conf, new_sector, previous,
4356                                        (bi->bi_rw&RWA_MASK), 0);
4357                 if (sh) {
4358                         if (unlikely(previous)) {
4359                                 /* expansion might have moved on while waiting for a
4360                                  * stripe, so we must do the range check again.
4361                                  * Expansion could still move past after this
4362                                  * test, but as we are holding a reference to
4363                                  * 'sh', we know that if that happens,
4364                                  *  STRIPE_EXPANDING will get set and the expansion
4365                                  * won't proceed until we finish with the stripe.
4366                                  */
4367                                 int must_retry = 0;
4368                                 spin_lock_irq(&conf->device_lock);
4369                                 if (mddev->reshape_backwards
4370                                     ? logical_sector >= conf->reshape_progress
4371                                     : logical_sector < conf->reshape_progress)
4372                                         /* mismatch, need to try again */
4373                                         must_retry = 1;
4374                                 spin_unlock_irq(&conf->device_lock);
4375                                 if (must_retry) {
4376                                         release_stripe(sh);
4377                                         schedule();
4378                                         goto retry;
4379                                 }
4380                         }
4381
4382                         if (rw == WRITE &&
4383                             logical_sector >= mddev->suspend_lo &&
4384                             logical_sector < mddev->suspend_hi) {
4385                                 release_stripe(sh);
4386                                 /* As the suspend_* range is controlled by
4387                                  * userspace, we want an interruptible
4388                                  * wait.
4389                                  */
4390                                 flush_signals(current);
4391                                 prepare_to_wait(&conf->wait_for_overlap,
4392                                                 &w, TASK_INTERRUPTIBLE);
4393                                 if (logical_sector >= mddev->suspend_lo &&
4394                                     logical_sector < mddev->suspend_hi)
4395                                         schedule();
4396                                 goto retry;
4397                         }
4398
4399                         if (test_bit(STRIPE_EXPANDING, &sh->state) ||
4400                             !add_stripe_bio(sh, bi, dd_idx, rw)) {
4401                                 /* Stripe is busy expanding or
4402                                  * add failed due to overlap.  Flush everything
4403                                  * and wait a while
4404                                  */
4405                                 md_wakeup_thread(mddev->thread);
4406                                 release_stripe(sh);
4407                                 schedule();
4408                                 goto retry;
4409                         }
4410                         finish_wait(&conf->wait_for_overlap, &w);
4411                         set_bit(STRIPE_HANDLE, &sh->state);
4412                         clear_bit(STRIPE_DELAYED, &sh->state);
4413                         if ((bi->bi_rw & REQ_SYNC) &&
4414                             !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4415                                 atomic_inc(&conf->preread_active_stripes);
4416                         release_stripe_plug(mddev, sh);
4417                 } else {
4418                         /* cannot get stripe for read-ahead, just give-up */
4419                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
4420                         finish_wait(&conf->wait_for_overlap, &w);
4421                         break;
4422                 }
4423         }
4424
4425         remaining = raid5_dec_bi_active_stripes(bi);
4426         if (remaining == 0) {
4427
4428                 if ( rw == WRITE )
4429                         md_write_end(mddev);
4430
4431                 trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
4432                                          bi, 0);
4433                 bio_endio(bi, 0);
4434         }
4435 }
4436
4437 static sector_t raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks);
4438
4439 static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *skipped)
4440 {
4441         /* reshaping is quite different to recovery/resync so it is
4442          * handled quite separately ... here.
4443          *
4444          * On each call to sync_request, we gather one chunk worth of
4445          * destination stripes and flag them as expanding.
4446          * Then we find all the source stripes and request reads.
4447          * As the reads complete, handle_stripe will copy the data
4448          * into the destination stripe and release that stripe.
4449          */
4450         struct r5conf *conf = mddev->private;
4451         struct stripe_head *sh;
4452         sector_t first_sector, last_sector;
4453         int raid_disks = conf->previous_raid_disks;
4454         int data_disks = raid_disks - conf->max_degraded;
4455         int new_data_disks = conf->raid_disks - conf->max_degraded;
4456         int i;
4457         int dd_idx;
4458         sector_t writepos, readpos, safepos;
4459         sector_t stripe_addr;
4460         int reshape_sectors;
4461         struct list_head stripes;
4462
4463         if (sector_nr == 0) {
4464                 /* If restarting in the middle, skip the initial sectors */
4465                 if (mddev->reshape_backwards &&
4466                     conf->reshape_progress < raid5_size(mddev, 0, 0)) {
4467                         sector_nr = raid5_size(mddev, 0, 0)
4468                                 - conf->reshape_progress;
4469                 } else if (!mddev->reshape_backwards &&
4470                            conf->reshape_progress > 0)
4471                         sector_nr = conf->reshape_progress;
4472                 sector_div(sector_nr, new_data_disks);
4473                 if (sector_nr) {
4474                         mddev->curr_resync_completed = sector_nr;
4475                         sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4476                         *skipped = 1;
4477                         return sector_nr;
4478                 }
4479         }
4480
4481         /* We need to process a full chunk at a time.
4482          * If old and new chunk sizes differ, we need to process the
4483          * largest of these
4484          */
4485         if (mddev->new_chunk_sectors > mddev->chunk_sectors)
4486                 reshape_sectors = mddev->new_chunk_sectors;
4487         else
4488                 reshape_sectors = mddev->chunk_sectors;
4489
4490         /* We update the metadata at least every 10 seconds, or when
4491          * the data about to be copied would over-write the source of
4492          * the data at the front of the range.  i.e. one new_stripe
4493          * along from reshape_progress new_maps to after where
4494          * reshape_safe old_maps to
4495          */
4496         writepos = conf->reshape_progress;
4497         sector_div(writepos, new_data_disks);
4498         readpos = conf->reshape_progress;
4499         sector_div(readpos, data_disks);
4500         safepos = conf->reshape_safe;
4501         sector_div(safepos, data_disks);
4502         if (mddev->reshape_backwards) {
4503                 writepos -= min_t(sector_t, reshape_sectors, writepos);
4504                 readpos += reshape_sectors;
4505                 safepos += reshape_sectors;
4506         } else {
4507                 writepos += reshape_sectors;
4508                 readpos -= min_t(sector_t, reshape_sectors, readpos);
4509                 safepos -= min_t(sector_t, reshape_sectors, safepos);
4510         }
4511
4512         /* Having calculated the 'writepos' possibly use it
4513          * to set 'stripe_addr' which is where we will write to.
4514          */
4515         if (mddev->reshape_backwards) {
4516                 BUG_ON(conf->reshape_progress == 0);
4517                 stripe_addr = writepos;
4518                 BUG_ON((mddev->dev_sectors &
4519                         ~((sector_t)reshape_sectors - 1))
4520                        - reshape_sectors - stripe_addr
4521                        != sector_nr);
4522         } else {
4523                 BUG_ON(writepos != sector_nr + reshape_sectors);
4524                 stripe_addr = sector_nr;
4525         }
4526
4527         /* 'writepos' is the most advanced device address we might write.
4528          * 'readpos' is the least advanced device address we might read.
4529          * 'safepos' is the least address recorded in the metadata as having
4530          *     been reshaped.
4531          * If there is a min_offset_diff, these are adjusted either by
4532          * increasing the safepos/readpos if diff is negative, or
4533          * increasing writepos if diff is positive.
4534          * If 'readpos' is then behind 'writepos', there is no way that we can
4535          * ensure safety in the face of a crash - that must be done by userspace
4536          * making a backup of the data.  So in that case there is no particular
4537          * rush to update metadata.
4538          * Otherwise if 'safepos' is behind 'writepos', then we really need to
4539          * update the metadata to advance 'safepos' to match 'readpos' so that
4540          * we can be safe in the event of a crash.
4541          * So we insist on updating metadata if safepos is behind writepos and
4542          * readpos is beyond writepos.
4543          * In any case, update the metadata every 10 seconds.
4544          * Maybe that number should be configurable, but I'm not sure it is
4545          * worth it.... maybe it could be a multiple of safemode_delay???
4546          */
4547         if (conf->min_offset_diff < 0) {
4548                 safepos += -conf->min_offset_diff;
4549                 readpos += -conf->min_offset_diff;
4550         } else
4551                 writepos += conf->min_offset_diff;
4552
4553         if ((mddev->reshape_backwards
4554              ? (safepos > writepos && readpos < writepos)
4555              : (safepos < writepos && readpos > writepos)) ||
4556             time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
4557                 /* Cannot proceed until we've updated the superblock... */
4558                 wait_event(conf->wait_for_overlap,
4559                            atomic_read(&conf->reshape_stripes)==0);
4560                 mddev->reshape_position = conf->reshape_progress;
4561                 mddev->curr_resync_completed = sector_nr;
4562                 conf->reshape_checkpoint = jiffies;
4563                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
4564                 md_wakeup_thread(mddev->thread);
4565                 wait_event(mddev->sb_wait, mddev->flags == 0 ||
4566                            kthread_should_stop());
4567                 spin_lock_irq(&conf->device_lock);
4568                 conf->reshape_safe = mddev->reshape_position;
4569                 spin_unlock_irq(&conf->device_lock);
4570                 wake_up(&conf->wait_for_overlap);
4571                 sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4572         }
4573
4574         INIT_LIST_HEAD(&stripes);
4575         for (i = 0; i < reshape_sectors; i += STRIPE_SECTORS) {
4576                 int j;
4577                 int skipped_disk = 0;
4578                 sh = get_active_stripe(conf, stripe_addr+i, 0, 0, 1);
4579                 set_bit(STRIPE_EXPANDING, &sh->state);
4580                 atomic_inc(&conf->reshape_stripes);
4581                 /* If any of this stripe is beyond the end of the old
4582                  * array, then we need to zero those blocks
4583                  */
4584                 for (j=sh->disks; j--;) {
4585                         sector_t s;
4586                         if (j == sh->pd_idx)
4587                                 continue;
4588                         if (conf->level == 6 &&
4589                             j == sh->qd_idx)
4590                                 continue;
4591                         s = compute_blocknr(sh, j, 0);
4592                         if (s < raid5_size(mddev, 0, 0)) {
4593                                 skipped_disk = 1;
4594                                 continue;
4595                         }
4596                         memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
4597                         set_bit(R5_Expanded, &sh->dev[j].flags);
4598                         set_bit(R5_UPTODATE, &sh->dev[j].flags);
4599                 }
4600                 if (!skipped_disk) {
4601                         set_bit(STRIPE_EXPAND_READY, &sh->state);
4602                         set_bit(STRIPE_HANDLE, &sh->state);
4603                 }
4604                 list_add(&sh->lru, &stripes);
4605         }
4606         spin_lock_irq(&conf->device_lock);
4607         if (mddev->reshape_backwards)
4608                 conf->reshape_progress -= reshape_sectors * new_data_disks;
4609         else
4610                 conf->reshape_progress += reshape_sectors * new_data_disks;
4611         spin_unlock_irq(&conf->device_lock);
4612         /* Ok, those stripe are ready. We can start scheduling
4613          * reads on the source stripes.
4614          * The source stripes are determined by mapping the first and last
4615          * block on the destination stripes.
4616          */
4617         first_sector =
4618                 raid5_compute_sector(conf, stripe_addr*(new_data_disks),
4619                                      1, &dd_idx, NULL);
4620         last_sector =
4621                 raid5_compute_sector(conf, ((stripe_addr+reshape_sectors)
4622                                             * new_data_disks - 1),
4623                                      1, &dd_idx, NULL);
4624         if (last_sector >= mddev->dev_sectors)
4625                 last_sector = mddev->dev_sectors - 1;
4626         while (first_sector <= last_sector) {
4627                 sh = get_active_stripe(conf, first_sector, 1, 0, 1);
4628                 set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
4629                 set_bit(STRIPE_HANDLE, &sh->state);
4630                 release_stripe(sh);
4631                 first_sector += STRIPE_SECTORS;
4632         }
4633         /* Now that the sources are clearly marked, we can release
4634          * the destination stripes
4635          */
4636         while (!list_empty(&stripes)) {
4637                 sh = list_entry(stripes.next, struct stripe_head, lru);
4638                 list_del_init(&sh->lru);
4639                 release_stripe(sh);
4640         }
4641         /* If this takes us to the resync_max point where we have to pause,
4642          * then we need to write out the superblock.
4643          */
4644         sector_nr += reshape_sectors;
4645         if ((sector_nr - mddev->curr_resync_completed) * 2
4646             >= mddev->resync_max - mddev->curr_resync_completed) {
4647                 /* Cannot proceed until we've updated the superblock... */
4648                 wait_event(conf->wait_for_overlap,
4649                            atomic_read(&conf->reshape_stripes) == 0);
4650                 mddev->reshape_position = conf->reshape_progress;
4651                 mddev->curr_resync_completed = sector_nr;
4652                 conf->reshape_checkpoint = jiffies;
4653                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
4654                 md_wakeup_thread(mddev->thread);
4655                 wait_event(mddev->sb_wait,
4656                            !test_bit(MD_CHANGE_DEVS, &mddev->flags)
4657                            || kthread_should_stop());
4658                 spin_lock_irq(&conf->device_lock);
4659                 conf->reshape_safe = mddev->reshape_position;
4660                 spin_unlock_irq(&conf->device_lock);
4661                 wake_up(&conf->wait_for_overlap);
4662                 sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4663         }
4664         return reshape_sectors;
4665 }
4666
4667 /* FIXME go_faster isn't used */
4668 static inline sector_t sync_request(struct mddev *mddev, sector_t sector_nr, int *skipped, int go_faster)
4669 {
4670         struct r5conf *conf = mddev->private;
4671         struct stripe_head *sh;
4672         sector_t max_sector = mddev->dev_sectors;
4673         sector_t sync_blocks;
4674         int still_degraded = 0;
4675         int i;
4676
4677         if (sector_nr >= max_sector) {
4678                 /* just being told to finish up .. nothing much to do */
4679
4680                 if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
4681                         end_reshape(conf);
4682                         return 0;
4683                 }
4684
4685                 if (mddev->curr_resync < max_sector) /* aborted */
4686                         bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
4687                                         &sync_blocks, 1);
4688                 else /* completed sync */
4689                         conf->fullsync = 0;
4690                 bitmap_close_sync(mddev->bitmap);
4691
4692                 return 0;
4693         }
4694
4695         /* Allow raid5_quiesce to complete */
4696         wait_event(conf->wait_for_overlap, conf->quiesce != 2);
4697
4698         if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
4699                 return reshape_request(mddev, sector_nr, skipped);
4700
4701         /* No need to check resync_max as we never do more than one
4702          * stripe, and as resync_max will always be on a chunk boundary,
4703          * if the check in md_do_sync didn't fire, there is no chance
4704          * of overstepping resync_max here
4705          */
4706
4707         /* if there is too many failed drives and we are trying
4708          * to resync, then assert that we are finished, because there is
4709          * nothing we can do.
4710          */
4711         if (mddev->degraded >= conf->max_degraded &&
4712             test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
4713                 sector_t rv = mddev->dev_sectors - sector_nr;
4714                 *skipped = 1;
4715                 return rv;
4716         }
4717         if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
4718             !conf->fullsync &&
4719             !bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
4720             sync_blocks >= STRIPE_SECTORS) {
4721                 /* we can skip this block, and probably more */
4722                 sync_blocks /= STRIPE_SECTORS;
4723                 *skipped = 1;
4724                 return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
4725         }
4726
4727         bitmap_cond_end_sync(mddev->bitmap, sector_nr);
4728
4729         sh = get_active_stripe(conf, sector_nr, 0, 1, 0);
4730         if (sh == NULL) {
4731                 sh = get_active_stripe(conf, sector_nr, 0, 0, 0);
4732                 /* make sure we don't swamp the stripe cache if someone else
4733                  * is trying to get access
4734                  */
4735                 schedule_timeout_uninterruptible(1);
4736         }
4737         /* Need to check if array will still be degraded after recovery/resync
4738          * We don't need to check the 'failed' flag as when that gets set,
4739          * recovery aborts.
4740          */
4741         for (i = 0; i < conf->raid_disks; i++)
4742                 if (conf->disks[i].rdev == NULL)
4743                         still_degraded = 1;
4744
4745         bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
4746
4747         set_bit(STRIPE_SYNC_REQUESTED, &sh->state);
4748
4749         handle_stripe(sh);
4750         release_stripe(sh);
4751
4752         return STRIPE_SECTORS;
4753 }
4754
4755 static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
4756 {
4757         /* We may not be able to submit a whole bio at once as there
4758          * may not be enough stripe_heads available.
4759          * We cannot pre-allocate enough stripe_heads as we may need
4760          * more than exist in the cache (if we allow ever large chunks).
4761          * So we do one stripe head at a time and record in
4762          * ->bi_hw_segments how many have been done.
4763          *
4764          * We *know* that this entire raid_bio is in one chunk, so
4765          * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
4766          */
4767         struct stripe_head *sh;
4768         int dd_idx;
4769         sector_t sector, logical_sector, last_sector;
4770         int scnt = 0;
4771         int remaining;
4772         int handled = 0;
4773
4774         logical_sector = raid_bio->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4775         sector = raid5_compute_sector(conf, logical_sector,
4776                                       0, &dd_idx, NULL);
4777         last_sector = bio_end_sector(raid_bio);
4778
4779         for (; logical_sector < last_sector;
4780              logical_sector += STRIPE_SECTORS,
4781                      sector += STRIPE_SECTORS,
4782                      scnt++) {
4783
4784                 if (scnt < raid5_bi_processed_stripes(raid_bio))
4785                         /* already done this stripe */
4786                         continue;
4787
4788                 sh = get_active_stripe(conf, sector, 0, 1, 0);
4789
4790                 if (!sh) {
4791                         /* failed to get a stripe - must wait */
4792                         raid5_set_bi_processed_stripes(raid_bio, scnt);
4793                         conf->retry_read_aligned = raid_bio;
4794                         return handled;
4795                 }
4796
4797                 if (!add_stripe_bio(sh, raid_bio, dd_idx, 0)) {
4798                         release_stripe(sh);
4799                         raid5_set_bi_processed_stripes(raid_bio, scnt);
4800                         conf->retry_read_aligned = raid_bio;
4801                         return handled;
4802                 }
4803
4804                 set_bit(R5_ReadNoMerge, &sh->dev[dd_idx].flags);
4805                 handle_stripe(sh);
4806                 release_stripe(sh);
4807                 handled++;
4808         }
4809         remaining = raid5_dec_bi_active_stripes(raid_bio);
4810         if (remaining == 0) {
4811                 trace_block_bio_complete(bdev_get_queue(raid_bio->bi_bdev),
4812                                          raid_bio, 0);
4813                 bio_endio(raid_bio, 0);
4814         }
4815         if (atomic_dec_and_test(&conf->active_aligned_reads))
4816                 wake_up(&conf->wait_for_stripe);
4817         return handled;
4818 }
4819
4820 #define MAX_STRIPE_BATCH 8
4821 static int handle_active_stripes(struct r5conf *conf)
4822 {
4823         struct stripe_head *batch[MAX_STRIPE_BATCH], *sh;
4824         int i, batch_size = 0;
4825
4826         while (batch_size < MAX_STRIPE_BATCH &&
4827                         (sh = __get_priority_stripe(conf)) != NULL)
4828                 batch[batch_size++] = sh;
4829
4830         if (batch_size == 0)
4831                 return batch_size;
4832         spin_unlock_irq(&conf->device_lock);
4833
4834         for (i = 0; i < batch_size; i++)
4835                 handle_stripe(batch[i]);
4836
4837         cond_resched();
4838
4839         spin_lock_irq(&conf->device_lock);
4840         for (i = 0; i < batch_size; i++)
4841                 __release_stripe(conf, batch[i]);
4842         return batch_size;
4843 }
4844
4845 /*
4846  * This is our raid5 kernel thread.
4847  *
4848  * We scan the hash table for stripes which can be handled now.
4849  * During the scan, completed stripes are saved for us by the interrupt
4850  * handler, so that they will not have to wait for our next wakeup.
4851  */
4852 static void raid5d(struct md_thread *thread)
4853 {
4854         struct mddev *mddev = thread->mddev;
4855         struct r5conf *conf = mddev->private;
4856         int handled;
4857         struct blk_plug plug;
4858
4859         pr_debug("+++ raid5d active\n");
4860
4861         md_check_recovery(mddev);
4862
4863         blk_start_plug(&plug);
4864         handled = 0;
4865         spin_lock_irq(&conf->device_lock);
4866         while (1) {
4867                 struct bio *bio;
4868                 int batch_size;
4869
4870                 if (
4871                     !list_empty(&conf->bitmap_list)) {
4872                         /* Now is a good time to flush some bitmap updates */
4873                         conf->seq_flush++;
4874                         spin_unlock_irq(&conf->device_lock);
4875                         bitmap_unplug(mddev->bitmap);
4876                         spin_lock_irq(&conf->device_lock);
4877                         conf->seq_write = conf->seq_flush;
4878                         activate_bit_delay(conf);
4879                 }
4880                 raid5_activate_delayed(conf);
4881
4882                 while ((bio = remove_bio_from_retry(conf))) {
4883                         int ok;
4884                         spin_unlock_irq(&conf->device_lock);
4885                         ok = retry_aligned_read(conf, bio);
4886                         spin_lock_irq(&conf->device_lock);
4887                         if (!ok)
4888                                 break;
4889                         handled++;
4890                 }
4891
4892                 batch_size = handle_active_stripes(conf);
4893                 if (!batch_size)
4894                         break;
4895                 handled += batch_size;
4896
4897                 if (mddev->flags & ~(1<<MD_CHANGE_PENDING)) {
4898                         spin_unlock_irq(&conf->device_lock);
4899                         md_check_recovery(mddev);
4900                         spin_lock_irq(&conf->device_lock);
4901                 }
4902         }
4903         pr_debug("%d stripes handled\n", handled);
4904
4905         spin_unlock_irq(&conf->device_lock);
4906
4907         async_tx_issue_pending_all();
4908         blk_finish_plug(&plug);
4909
4910         pr_debug("--- raid5d inactive\n");
4911 }
4912
4913 static ssize_t
4914 raid5_show_stripe_cache_size(struct mddev *mddev, char *page)
4915 {
4916         struct r5conf *conf = mddev->private;
4917         if (conf)
4918                 return sprintf(page, "%d\n", conf->max_nr_stripes);
4919         else
4920                 return 0;
4921 }
4922
4923 int
4924 raid5_set_cache_size(struct mddev *mddev, int size)
4925 {
4926         struct r5conf *conf = mddev->private;
4927         int err;
4928
4929         if (size <= 16 || size > 32768)
4930                 return -EINVAL;
4931         while (size < conf->max_nr_stripes) {
4932                 if (drop_one_stripe(conf))
4933                         conf->max_nr_stripes--;
4934                 else
4935                         break;
4936         }
4937         err = md_allow_write(mddev);
4938         if (err)
4939                 return err;
4940         while (size > conf->max_nr_stripes) {
4941                 if (grow_one_stripe(conf))
4942                         conf->max_nr_stripes++;
4943                 else break;
4944         }
4945         return 0;
4946 }
4947 EXPORT_SYMBOL(raid5_set_cache_size);
4948
4949 static ssize_t
4950 raid5_store_stripe_cache_size(struct mddev *mddev, const char *page, size_t len)
4951 {
4952         struct r5conf *conf = mddev->private;
4953         unsigned long new;
4954         int err;
4955
4956         if (len >= PAGE_SIZE)
4957                 return -EINVAL;
4958         if (!conf)
4959                 return -ENODEV;
4960
4961         if (strict_strtoul(page, 10, &new))
4962                 return -EINVAL;
4963         err = raid5_set_cache_size(mddev, new);
4964         if (err)
4965                 return err;
4966         return len;
4967 }
4968
4969 static struct md_sysfs_entry
4970 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
4971                                 raid5_show_stripe_cache_size,
4972                                 raid5_store_stripe_cache_size);
4973
4974 static ssize_t
4975 raid5_show_preread_threshold(struct mddev *mddev, char *page)
4976 {
4977         struct r5conf *conf = mddev->private;
4978         if (conf)
4979                 return sprintf(page, "%d\n", conf->bypass_threshold);
4980         else
4981                 return 0;
4982 }
4983
4984 static ssize_t
4985 raid5_store_preread_threshold(struct mddev *mddev, const char *page, size_t len)
4986 {
4987         struct r5conf *conf = mddev->private;
4988         unsigned long new;
4989         if (len >= PAGE_SIZE)
4990                 return -EINVAL;
4991         if (!conf)
4992                 return -ENODEV;
4993
4994         if (strict_strtoul(page, 10, &new))
4995                 return -EINVAL;
4996         if (new > conf->max_nr_stripes)
4997                 return -EINVAL;
4998         conf->bypass_threshold = new;
4999         return len;
5000 }
5001
5002 static struct md_sysfs_entry
5003 raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold,
5004                                         S_IRUGO | S_IWUSR,
5005                                         raid5_show_preread_threshold,
5006                                         raid5_store_preread_threshold);
5007
5008 static ssize_t
5009 stripe_cache_active_show(struct mddev *mddev, char *page)
5010 {
5011         struct r5conf *conf = mddev->private;
5012         if (conf)
5013                 return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
5014         else
5015                 return 0;
5016 }
5017
5018 static struct md_sysfs_entry
5019 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
5020
5021 static struct attribute *raid5_attrs[] =  {
5022         &raid5_stripecache_size.attr,
5023         &raid5_stripecache_active.attr,
5024         &raid5_preread_bypass_threshold.attr,
5025         NULL,
5026 };
5027 static struct attribute_group raid5_attrs_group = {
5028         .name = NULL,
5029         .attrs = raid5_attrs,
5030 };
5031
5032 static sector_t
5033 raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks)
5034 {
5035         struct r5conf *conf = mddev->private;
5036
5037         if (!sectors)
5038                 sectors = mddev->dev_sectors;
5039         if (!raid_disks)
5040                 /* size is defined by the smallest of previous and new size */
5041                 raid_disks = min(conf->raid_disks, conf->previous_raid_disks);
5042
5043         sectors &= ~((sector_t)mddev->chunk_sectors - 1);
5044         sectors &= ~((sector_t)mddev->new_chunk_sectors - 1);
5045         return sectors * (raid_disks - conf->max_degraded);
5046 }
5047
5048 static void free_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
5049 {
5050         safe_put_page(percpu->spare_page);
5051         kfree(percpu->scribble);
5052         percpu->spare_page = NULL;
5053         percpu->scribble = NULL;
5054 }
5055
5056 static int alloc_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
5057 {
5058         if (conf->level == 6 && !percpu->spare_page)
5059                 percpu->spare_page = alloc_page(GFP_KERNEL);
5060         if (!percpu->scribble)
5061                 percpu->scribble = kmalloc(conf->scribble_len, GFP_KERNEL);
5062
5063         if (!percpu->scribble || (conf->level == 6 && !percpu->spare_page)) {
5064                 free_scratch_buffer(conf, percpu);
5065                 return -ENOMEM;
5066         }
5067
5068         return 0;
5069 }
5070
5071 static void raid5_free_percpu(struct r5conf *conf)
5072 {
5073         unsigned long cpu;
5074
5075         if (!conf->percpu)
5076                 return;
5077
5078 #ifdef CONFIG_HOTPLUG_CPU
5079         unregister_cpu_notifier(&conf->cpu_notify);
5080 #endif
5081
5082         get_online_cpus();
5083         for_each_possible_cpu(cpu)
5084                 free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
5085         put_online_cpus();
5086
5087         free_percpu(conf->percpu);
5088 }
5089
5090 static void free_conf(struct r5conf *conf)
5091 {
5092         shrink_stripes(conf);
5093         raid5_free_percpu(conf);
5094         kfree(conf->disks);
5095         kfree(conf->stripe_hashtbl);
5096         kfree(conf);
5097 }
5098
5099 #ifdef CONFIG_HOTPLUG_CPU
5100 static int raid456_cpu_notify(struct notifier_block *nfb, unsigned long action,
5101                               void *hcpu)
5102 {
5103         struct r5conf *conf = container_of(nfb, struct r5conf, cpu_notify);
5104         long cpu = (long)hcpu;
5105         struct raid5_percpu *percpu = per_cpu_ptr(conf->percpu, cpu);
5106
5107         switch (action) {
5108         case CPU_UP_PREPARE:
5109         case CPU_UP_PREPARE_FROZEN:
5110                 if (alloc_scratch_buffer(conf, percpu)) {
5111                         pr_err("%s: failed memory allocation for cpu%ld\n",
5112                                __func__, cpu);
5113                         return notifier_from_errno(-ENOMEM);
5114                 }
5115                 break;
5116         case CPU_DEAD:
5117         case CPU_DEAD_FROZEN:
5118                 free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
5119                 break;
5120         default:
5121                 break;
5122         }
5123         return NOTIFY_OK;
5124 }
5125 #endif
5126
5127 static int raid5_alloc_percpu(struct r5conf *conf)
5128 {
5129         unsigned long cpu;
5130         int err = 0;
5131
5132         conf->percpu = alloc_percpu(struct raid5_percpu);
5133         if (!conf->percpu)
5134                 return -ENOMEM;
5135
5136 #ifdef CONFIG_HOTPLUG_CPU
5137         conf->cpu_notify.notifier_call = raid456_cpu_notify;
5138         conf->cpu_notify.priority = 0;
5139         err = register_cpu_notifier(&conf->cpu_notify);
5140         if (err)
5141                 return err;
5142 #endif
5143
5144         get_online_cpus();
5145         for_each_present_cpu(cpu) {
5146                 err = alloc_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
5147                 if (err) {
5148                         pr_err("%s: failed memory allocation for cpu%ld\n",
5149                                __func__, cpu);
5150                         break;
5151                 }
5152         }
5153         put_online_cpus();
5154
5155         return err;
5156 }
5157
5158 static struct r5conf *setup_conf(struct mddev *mddev)
5159 {
5160         struct r5conf *conf;
5161         int raid_disk, memory, max_disks;
5162         struct md_rdev *rdev;
5163         struct disk_info *disk;
5164         char pers_name[6];
5165
5166         if (mddev->new_level != 5
5167             && mddev->new_level != 4
5168             && mddev->new_level != 6) {
5169                 printk(KERN_ERR "md/raid:%s: raid level not set to 4/5/6 (%d)\n",
5170                        mdname(mddev), mddev->new_level);
5171                 return ERR_PTR(-EIO);
5172         }
5173         if ((mddev->new_level == 5
5174              && !algorithm_valid_raid5(mddev->new_layout)) ||
5175             (mddev->new_level == 6
5176              && !algorithm_valid_raid6(mddev->new_layout))) {
5177                 printk(KERN_ERR "md/raid:%s: layout %d not supported\n",
5178                        mdname(mddev), mddev->new_layout);
5179                 return ERR_PTR(-EIO);
5180         }
5181         if (mddev->new_level == 6 && mddev->raid_disks < 4) {
5182                 printk(KERN_ERR "md/raid:%s: not enough configured devices (%d, minimum 4)\n",
5183                        mdname(mddev), mddev->raid_disks);
5184                 return ERR_PTR(-EINVAL);
5185         }
5186
5187         if (!mddev->new_chunk_sectors ||
5188             (mddev->new_chunk_sectors << 9) % PAGE_SIZE ||
5189             !is_power_of_2(mddev->new_chunk_sectors)) {
5190                 printk(KERN_ERR "md/raid:%s: invalid chunk size %d\n",
5191                        mdname(mddev), mddev->new_chunk_sectors << 9);
5192                 return ERR_PTR(-EINVAL);
5193         }
5194
5195         conf = kzalloc(sizeof(struct r5conf), GFP_KERNEL);
5196         if (conf == NULL)
5197                 goto abort;
5198         spin_lock_init(&conf->device_lock);
5199         init_waitqueue_head(&conf->wait_for_stripe);
5200         init_waitqueue_head(&conf->wait_for_overlap);
5201         INIT_LIST_HEAD(&conf->handle_list);
5202         INIT_LIST_HEAD(&conf->hold_list);
5203         INIT_LIST_HEAD(&conf->delayed_list);
5204         INIT_LIST_HEAD(&conf->bitmap_list);
5205         INIT_LIST_HEAD(&conf->inactive_list);
5206         atomic_set(&conf->active_stripes, 0);
5207         atomic_set(&conf->preread_active_stripes, 0);
5208         atomic_set(&conf->active_aligned_reads, 0);
5209         conf->bypass_threshold = BYPASS_THRESHOLD;
5210         conf->recovery_disabled = mddev->recovery_disabled - 1;
5211
5212         conf->raid_disks = mddev->raid_disks;
5213         if (mddev->reshape_position == MaxSector)
5214                 conf->previous_raid_disks = mddev->raid_disks;
5215         else
5216                 conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
5217         max_disks = max(conf->raid_disks, conf->previous_raid_disks);
5218         conf->scribble_len = scribble_len(max_disks);
5219
5220         conf->disks = kzalloc(max_disks * sizeof(struct disk_info),
5221                               GFP_KERNEL);
5222         if (!conf->disks)
5223                 goto abort;
5224
5225         conf->mddev = mddev;
5226
5227         if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
5228                 goto abort;
5229
5230         conf->level = mddev->new_level;
5231         if (raid5_alloc_percpu(conf) != 0)
5232                 goto abort;
5233
5234         pr_debug("raid456: run(%s) called.\n", mdname(mddev));
5235
5236         rdev_for_each(rdev, mddev) {
5237                 raid_disk = rdev->raid_disk;
5238                 if (raid_disk >= max_disks
5239                     || raid_disk < 0)
5240                         continue;
5241                 disk = conf->disks + raid_disk;
5242
5243                 if (test_bit(Replacement, &rdev->flags)) {
5244                         if (disk->replacement)
5245                                 goto abort;
5246                         disk->replacement = rdev;
5247                 } else {
5248                         if (disk->rdev)
5249                                 goto abort;
5250                         disk->rdev = rdev;
5251                 }
5252
5253                 if (test_bit(In_sync, &rdev->flags)) {
5254                         char b[BDEVNAME_SIZE];
5255                         printk(KERN_INFO "md/raid:%s: device %s operational as raid"
5256                                " disk %d\n",
5257                                mdname(mddev), bdevname(rdev->bdev, b), raid_disk);
5258                 } else if (rdev->saved_raid_disk != raid_disk)
5259                         /* Cannot rely on bitmap to complete recovery */
5260                         conf->fullsync = 1;
5261         }
5262
5263         conf->chunk_sectors = mddev->new_chunk_sectors;
5264         conf->level = mddev->new_level;
5265         if (conf->level == 6)
5266                 conf->max_degraded = 2;
5267         else
5268                 conf->max_degraded = 1;
5269         conf->algorithm = mddev->new_layout;
5270         conf->max_nr_stripes = NR_STRIPES;
5271         conf->reshape_progress = mddev->reshape_position;
5272         if (conf->reshape_progress != MaxSector) {
5273                 conf->prev_chunk_sectors = mddev->chunk_sectors;
5274                 conf->prev_algo = mddev->layout;
5275         }
5276
5277         memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
5278                  max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
5279         if (grow_stripes(conf, conf->max_nr_stripes)) {
5280                 printk(KERN_ERR
5281                        "md/raid:%s: couldn't allocate %dkB for buffers\n",
5282                        mdname(mddev), memory);
5283                 goto abort;
5284         } else
5285                 printk(KERN_INFO "md/raid:%s: allocated %dkB\n",
5286                        mdname(mddev), memory);
5287
5288         sprintf(pers_name, "raid%d", mddev->new_level);
5289         conf->thread = md_register_thread(raid5d, mddev, pers_name);
5290         if (!conf->thread) {
5291                 printk(KERN_ERR
5292                        "md/raid:%s: couldn't allocate thread.\n",
5293                        mdname(mddev));
5294                 goto abort;
5295         }
5296
5297         return conf;
5298
5299  abort:
5300         if (conf) {
5301                 free_conf(conf);
5302                 return ERR_PTR(-EIO);
5303         } else
5304                 return ERR_PTR(-ENOMEM);
5305 }
5306
5307
5308 static int only_parity(int raid_disk, int algo, int raid_disks, int max_degraded)
5309 {
5310         switch (algo) {
5311         case ALGORITHM_PARITY_0:
5312                 if (raid_disk < max_degraded)
5313                         return 1;
5314                 break;
5315         case ALGORITHM_PARITY_N:
5316                 if (raid_disk >= raid_disks - max_degraded)
5317                         return 1;
5318                 break;
5319         case ALGORITHM_PARITY_0_6:
5320                 if (raid_disk == 0 ||
5321                     raid_disk == raid_disks - 1)
5322                         return 1;
5323                 break;
5324         case ALGORITHM_LEFT_ASYMMETRIC_6:
5325         case ALGORITHM_RIGHT_ASYMMETRIC_6:
5326         case ALGORITHM_LEFT_SYMMETRIC_6:
5327         case ALGORITHM_RIGHT_SYMMETRIC_6:
5328                 if (raid_disk == raid_disks - 1)
5329                         return 1;
5330         }
5331         return 0;
5332 }
5333
5334 static int run(struct mddev *mddev)
5335 {
5336         struct r5conf *conf;
5337         int working_disks = 0;
5338         int dirty_parity_disks = 0;
5339         struct md_rdev *rdev;
5340         sector_t reshape_offset = 0;
5341         int i;
5342         long long min_offset_diff = 0;
5343         int first = 1;
5344
5345         if (mddev->recovery_cp != MaxSector)
5346                 printk(KERN_NOTICE "md/raid:%s: not clean"
5347                        " -- starting background reconstruction\n",
5348                        mdname(mddev));
5349
5350         rdev_for_each(rdev, mddev) {
5351                 long long diff;
5352                 if (rdev->raid_disk < 0)
5353                         continue;
5354                 diff = (rdev->new_data_offset - rdev->data_offset);
5355                 if (first) {
5356                         min_offset_diff = diff;
5357                         first = 0;
5358                 } else if (mddev->reshape_backwards &&
5359                          diff < min_offset_diff)
5360                         min_offset_diff = diff;
5361                 else if (!mddev->reshape_backwards &&
5362                          diff > min_offset_diff)
5363                         min_offset_diff = diff;
5364         }
5365
5366         if (mddev->reshape_position != MaxSector) {
5367                 /* Check that we can continue the reshape.
5368                  * Difficulties arise if the stripe we would write to
5369                  * next is at or after the stripe we would read from next.
5370                  * For a reshape that changes the number of devices, this
5371                  * is only possible for a very short time, and mdadm makes
5372                  * sure that time appears to have past before assembling
5373                  * the array.  So we fail if that time hasn't passed.
5374                  * For a reshape that keeps the number of devices the same
5375                  * mdadm must be monitoring the reshape can keeping the
5376                  * critical areas read-only and backed up.  It will start
5377                  * the array in read-only mode, so we check for that.
5378                  */
5379                 sector_t here_new, here_old;
5380                 int old_disks;
5381                 int max_degraded = (mddev->level == 6 ? 2 : 1);
5382
5383                 if (mddev->new_level != mddev->level) {
5384                         printk(KERN_ERR "md/raid:%s: unsupported reshape "
5385                                "required - aborting.\n",
5386                                mdname(mddev));
5387                         return -EINVAL;
5388                 }
5389                 old_disks = mddev->raid_disks - mddev->delta_disks;
5390                 /* reshape_position must be on a new-stripe boundary, and one
5391                  * further up in new geometry must map after here in old
5392                  * geometry.
5393                  */
5394                 here_new = mddev->reshape_position;
5395                 if (sector_div(here_new, mddev->new_chunk_sectors *
5396                                (mddev->raid_disks - max_degraded))) {
5397                         printk(KERN_ERR "md/raid:%s: reshape_position not "
5398                                "on a stripe boundary\n", mdname(mddev));
5399                         return -EINVAL;
5400                 }
5401                 reshape_offset = here_new * mddev->new_chunk_sectors;
5402                 /* here_new is the stripe we will write to */
5403                 here_old = mddev->reshape_position;
5404                 sector_div(here_old, mddev->chunk_sectors *
5405                            (old_disks-max_degraded));
5406                 /* here_old is the first stripe that we might need to read
5407                  * from */
5408                 if (mddev->delta_disks == 0) {
5409                         if ((here_new * mddev->new_chunk_sectors !=
5410                              here_old * mddev->chunk_sectors)) {
5411                                 printk(KERN_ERR "md/raid:%s: reshape position is"
5412                                        " confused - aborting\n", mdname(mddev));
5413                                 return -EINVAL;
5414                         }
5415                         /* We cannot be sure it is safe to start an in-place
5416                          * reshape.  It is only safe if user-space is monitoring
5417                          * and taking constant backups.
5418                          * mdadm always starts a situation like this in
5419                          * readonly mode so it can take control before
5420                          * allowing any writes.  So just check for that.
5421                          */
5422                         if (abs(min_offset_diff) >= mddev->chunk_sectors &&
5423                             abs(min_offset_diff) >= mddev->new_chunk_sectors)
5424                                 /* not really in-place - so OK */;
5425                         else if (mddev->ro == 0) {
5426                                 printk(KERN_ERR "md/raid:%s: in-place reshape "
5427                                        "must be started in read-only mode "
5428                                        "- aborting\n",
5429                                        mdname(mddev));
5430                                 return -EINVAL;
5431                         }
5432                 } else if (mddev->reshape_backwards
5433                     ? (here_new * mddev->new_chunk_sectors + min_offset_diff <=
5434                        here_old * mddev->chunk_sectors)
5435                     : (here_new * mddev->new_chunk_sectors >=
5436                        here_old * mddev->chunk_sectors + (-min_offset_diff))) {
5437                         /* Reading from the same stripe as writing to - bad */
5438                         printk(KERN_ERR "md/raid:%s: reshape_position too early for "
5439                                "auto-recovery - aborting.\n",
5440                                mdname(mddev));
5441                         return -EINVAL;
5442                 }
5443                 printk(KERN_INFO "md/raid:%s: reshape will continue\n",
5444                        mdname(mddev));
5445                 /* OK, we should be able to continue; */
5446         } else {
5447                 BUG_ON(mddev->level != mddev->new_level);
5448                 BUG_ON(mddev->layout != mddev->new_layout);
5449                 BUG_ON(mddev->chunk_sectors != mddev->new_chunk_sectors);
5450                 BUG_ON(mddev->delta_disks != 0);
5451         }
5452
5453         if (mddev->private == NULL)
5454                 conf = setup_conf(mddev);
5455         else
5456                 conf = mddev->private;
5457
5458         if (IS_ERR(conf))
5459                 return PTR_ERR(conf);
5460
5461         conf->min_offset_diff = min_offset_diff;
5462         mddev->thread = conf->thread;
5463         conf->thread = NULL;
5464         mddev->private = conf;
5465
5466         for (i = 0; i < conf->raid_disks && conf->previous_raid_disks;
5467              i++) {
5468                 rdev = conf->disks[i].rdev;
5469                 if (!rdev && conf->disks[i].replacement) {
5470                         /* The replacement is all we have yet */
5471                         rdev = conf->disks[i].replacement;
5472                         conf->disks[i].replacement = NULL;
5473                         clear_bit(Replacement, &rdev->flags);
5474                         conf->disks[i].rdev = rdev;
5475                 }
5476                 if (!rdev)
5477                         continue;
5478                 if (conf->disks[i].replacement &&
5479                     conf->reshape_progress != MaxSector) {
5480                         /* replacements and reshape simply do not mix. */
5481                         printk(KERN_ERR "md: cannot handle concurrent "
5482                                "replacement and reshape.\n");
5483                         goto abort;
5484                 }
5485                 if (test_bit(In_sync, &rdev->flags)) {
5486                         working_disks++;
5487                         continue;
5488                 }
5489                 /* This disc is not fully in-sync.  However if it
5490                  * just stored parity (beyond the recovery_offset),
5491                  * when we don't need to be concerned about the
5492                  * array being dirty.
5493                  * When reshape goes 'backwards', we never have
5494                  * partially completed devices, so we only need
5495                  * to worry about reshape going forwards.
5496                  */
5497                 /* Hack because v0.91 doesn't store recovery_offset properly. */
5498                 if (mddev->major_version == 0 &&
5499                     mddev->minor_version > 90)
5500                         rdev->recovery_offset = reshape_offset;
5501
5502                 if (rdev->recovery_offset < reshape_offset) {
5503                         /* We need to check old and new layout */
5504                         if (!only_parity(rdev->raid_disk,
5505                                          conf->algorithm,
5506                                          conf->raid_disks,
5507                                          conf->max_degraded))
5508                                 continue;
5509                 }
5510                 if (!only_parity(rdev->raid_disk,
5511                                  conf->prev_algo,
5512                                  conf->previous_raid_disks,
5513                                  conf->max_degraded))
5514                         continue;
5515                 dirty_parity_disks++;
5516         }
5517
5518         /*
5519          * 0 for a fully functional array, 1 or 2 for a degraded array.
5520          */
5521         mddev->degraded = calc_degraded(conf);
5522
5523         if (has_failed(conf)) {
5524                 printk(KERN_ERR "md/raid:%s: not enough operational devices"
5525                         " (%d/%d failed)\n",
5526                         mdname(mddev), mddev->degraded, conf->raid_disks);
5527                 goto abort;
5528         }
5529
5530         /* device size must be a multiple of chunk size */
5531         mddev->dev_sectors &= ~(mddev->chunk_sectors - 1);
5532         mddev->resync_max_sectors = mddev->dev_sectors;
5533
5534         if (mddev->degraded > dirty_parity_disks &&
5535             mddev->recovery_cp != MaxSector) {
5536                 if (mddev->ok_start_degraded)
5537                         printk(KERN_WARNING
5538                                "md/raid:%s: starting dirty degraded array"
5539                                " - data corruption possible.\n",
5540                                mdname(mddev));
5541                 else {
5542                         printk(KERN_ERR
5543                                "md/raid:%s: cannot start dirty degraded array.\n",
5544                                mdname(mddev));
5545                         goto abort;
5546                 }
5547         }
5548
5549         if (mddev->degraded == 0)
5550                 printk(KERN_INFO "md/raid:%s: raid level %d active with %d out of %d"
5551                        " devices, algorithm %d\n", mdname(mddev), conf->level,
5552                        mddev->raid_disks-mddev->degraded, mddev->raid_disks,
5553                        mddev->new_layout);
5554         else
5555                 printk(KERN_ALERT "md/raid:%s: raid level %d active with %d"
5556                        " out of %d devices, algorithm %d\n",
5557                        mdname(mddev), conf->level,
5558                        mddev->raid_disks - mddev->degraded,
5559                        mddev->raid_disks, mddev->new_layout);
5560
5561         print_raid5_conf(conf);
5562
5563         if (conf->reshape_progress != MaxSector) {
5564                 conf->reshape_safe = conf->reshape_progress;
5565                 atomic_set(&conf->reshape_stripes, 0);
5566                 clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
5567                 clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
5568                 set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
5569                 set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
5570                 mddev->sync_thread = md_register_thread(md_do_sync, mddev,
5571                                                         "reshape");
5572         }
5573
5574
5575         /* Ok, everything is just fine now */
5576         if (mddev->to_remove == &raid5_attrs_group)
5577                 mddev->to_remove = NULL;
5578         else if (mddev->kobj.sd &&
5579             sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
5580                 printk(KERN_WARNING
5581                        "raid5: failed to create sysfs attributes for %s\n",
5582                        mdname(mddev));
5583         md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
5584
5585         if (mddev->queue) {
5586                 int chunk_size;
5587                 bool discard_supported = true;
5588                 /* read-ahead size must cover two whole stripes, which
5589                  * is 2 * (datadisks) * chunksize where 'n' is the
5590                  * number of raid devices
5591                  */
5592                 int data_disks = conf->previous_raid_disks - conf->max_degraded;
5593                 int stripe = data_disks *
5594                         ((mddev->chunk_sectors << 9) / PAGE_SIZE);
5595                 if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
5596                         mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
5597
5598                 blk_queue_merge_bvec(mddev->queue, raid5_mergeable_bvec);
5599
5600                 mddev->queue->backing_dev_info.congested_data = mddev;
5601                 mddev->queue->backing_dev_info.congested_fn = raid5_congested;
5602
5603                 chunk_size = mddev->chunk_sectors << 9;
5604                 blk_queue_io_min(mddev->queue, chunk_size);
5605                 blk_queue_io_opt(mddev->queue, chunk_size *
5606                                  (conf->raid_disks - conf->max_degraded));
5607                 /*
5608                  * We can only discard a whole stripe. It doesn't make sense to
5609                  * discard data disk but write parity disk
5610                  */
5611                 stripe = stripe * PAGE_SIZE;
5612                 /* Round up to power of 2, as discard handling
5613                  * currently assumes that */
5614                 while ((stripe-1) & stripe)
5615                         stripe = (stripe | (stripe-1)) + 1;
5616                 mddev->queue->limits.discard_alignment = stripe;
5617                 mddev->queue->limits.discard_granularity = stripe;
5618                 /*
5619                  * unaligned part of discard request will be ignored, so can't
5620                  * guarantee discard_zeroes_data
5621                  */
5622                 mddev->queue->limits.discard_zeroes_data = 0;
5623
5624                 blk_queue_max_write_same_sectors(mddev->queue, 0);
5625
5626                 rdev_for_each(rdev, mddev) {
5627                         disk_stack_limits(mddev->gendisk, rdev->bdev,
5628                                           rdev->data_offset << 9);
5629                         disk_stack_limits(mddev->gendisk, rdev->bdev,
5630                                           rdev->new_data_offset << 9);
5631                         /*
5632                          * discard_zeroes_data is required, otherwise data
5633                          * could be lost. Consider a scenario: discard a stripe
5634                          * (the stripe could be inconsistent if
5635                          * discard_zeroes_data is 0); write one disk of the
5636                          * stripe (the stripe could be inconsistent again
5637                          * depending on which disks are used to calculate
5638                          * parity); the disk is broken; The stripe data of this
5639                          * disk is lost.
5640                          */
5641                         if (!blk_queue_discard(bdev_get_queue(rdev->bdev)) ||
5642                             !bdev_get_queue(rdev->bdev)->
5643                                                 limits.discard_zeroes_data)
5644                                 discard_supported = false;
5645                         /* Unfortunately, discard_zeroes_data is not currently
5646                          * a guarantee - just a hint.  So we only allow DISCARD
5647                          * if the sysadmin has confirmed that only safe devices
5648                          * are in use by setting a module parameter.
5649                          */
5650                         if (!devices_handle_discard_safely) {
5651                                 if (discard_supported) {
5652                                         pr_info("md/raid456: discard support disabled due to uncertainty.\n");
5653                                         pr_info("Set raid456.devices_handle_discard_safely=Y to override.\n");
5654                                 }
5655                                 discard_supported = false;
5656                         }
5657                 }
5658
5659                 if (discard_supported &&
5660                    mddev->queue->limits.max_discard_sectors >= stripe &&
5661                    mddev->queue->limits.discard_granularity >= stripe)
5662                         queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
5663                                                 mddev->queue);
5664                 else
5665                         queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD,
5666                                                 mddev->queue);
5667         }
5668
5669         return 0;
5670 abort:
5671         md_unregister_thread(&mddev->thread);
5672         print_raid5_conf(conf);
5673         free_conf(conf);
5674         mddev->private = NULL;
5675         printk(KERN_ALERT "md/raid:%s: failed to run raid set.\n", mdname(mddev));
5676         return -EIO;
5677 }
5678
5679 static int stop(struct mddev *mddev)
5680 {
5681         struct r5conf *conf = mddev->private;
5682
5683         md_unregister_thread(&mddev->thread);
5684         if (mddev->queue)
5685                 mddev->queue->backing_dev_info.congested_fn = NULL;
5686         free_conf(conf);
5687         mddev->private = NULL;
5688         mddev->to_remove = &raid5_attrs_group;
5689         return 0;
5690 }
5691
5692 static void status(struct seq_file *seq, struct mddev *mddev)
5693 {
5694         struct r5conf *conf = mddev->private;
5695         int i;
5696
5697         seq_printf(seq, " level %d, %dk chunk, algorithm %d", mddev->level,
5698                 mddev->chunk_sectors / 2, mddev->layout);
5699         seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded);
5700         for (i = 0; i < conf->raid_disks; i++)
5701                 seq_printf (seq, "%s",
5702                                conf->disks[i].rdev &&
5703                                test_bit(In_sync, &conf->disks[i].rdev->flags) ? "U" : "_");
5704         seq_printf (seq, "]");
5705 }
5706
5707 static void print_raid5_conf (struct r5conf *conf)
5708 {
5709         int i;
5710         struct disk_info *tmp;
5711
5712         printk(KERN_DEBUG "RAID conf printout:\n");
5713         if (!conf) {
5714                 printk("(conf==NULL)\n");
5715                 return;
5716         }
5717         printk(KERN_DEBUG " --- level:%d rd:%d wd:%d\n", conf->level,
5718                conf->raid_disks,
5719                conf->raid_disks - conf->mddev->degraded);
5720
5721         for (i = 0; i < conf->raid_disks; i++) {
5722                 char b[BDEVNAME_SIZE];
5723                 tmp = conf->disks + i;
5724                 if (tmp->rdev)
5725                         printk(KERN_DEBUG " disk %d, o:%d, dev:%s\n",
5726                                i, !test_bit(Faulty, &tmp->rdev->flags),
5727                                bdevname(tmp->rdev->bdev, b));
5728         }
5729 }
5730
5731 static int raid5_spare_active(struct mddev *mddev)
5732 {
5733         int i;
5734         struct r5conf *conf = mddev->private;
5735         struct disk_info *tmp;
5736         int count = 0;
5737         unsigned long flags;
5738
5739         for (i = 0; i < conf->raid_disks; i++) {
5740                 tmp = conf->disks + i;
5741                 if (tmp->replacement
5742                     && tmp->replacement->recovery_offset == MaxSector
5743                     && !test_bit(Faulty, &tmp->replacement->flags)
5744                     && !test_and_set_bit(In_sync, &tmp->replacement->flags)) {
5745                         /* Replacement has just become active. */
5746                         if (!tmp->rdev
5747                             || !test_and_clear_bit(In_sync, &tmp->rdev->flags))
5748                                 count++;
5749                         if (tmp->rdev) {
5750                                 /* Replaced device not technically faulty,
5751                                  * but we need to be sure it gets removed
5752                                  * and never re-added.
5753                                  */
5754                                 set_bit(Faulty, &tmp->rdev->flags);
5755                                 sysfs_notify_dirent_safe(
5756                                         tmp->rdev->sysfs_state);
5757                         }
5758                         sysfs_notify_dirent_safe(tmp->replacement->sysfs_state);
5759                 } else if (tmp->rdev
5760                     && tmp->rdev->recovery_offset == MaxSector
5761                     && !test_bit(Faulty, &tmp->rdev->flags)
5762                     && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
5763                         count++;
5764                         sysfs_notify_dirent_safe(tmp->rdev->sysfs_state);
5765                 }
5766         }
5767         spin_lock_irqsave(&conf->device_lock, flags);
5768         mddev->degraded = calc_degraded(conf);
5769         spin_unlock_irqrestore(&conf->device_lock, flags);
5770         print_raid5_conf(conf);
5771         return count;
5772 }
5773
5774 static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
5775 {
5776         struct r5conf *conf = mddev->private;
5777         int err = 0;
5778         int number = rdev->raid_disk;
5779         struct md_rdev **rdevp;
5780         struct disk_info *p = conf->disks + number;
5781
5782         print_raid5_conf(conf);
5783         if (rdev == p->rdev)
5784                 rdevp = &p->rdev;
5785         else if (rdev == p->replacement)
5786                 rdevp = &p->replacement;
5787         else
5788                 return 0;
5789
5790         if (number >= conf->raid_disks &&
5791             conf->reshape_progress == MaxSector)
5792                 clear_bit(In_sync, &rdev->flags);
5793
5794         if (test_bit(In_sync, &rdev->flags) ||
5795             atomic_read(&rdev->nr_pending)) {
5796                 err = -EBUSY;
5797                 goto abort;
5798         }
5799         /* Only remove non-faulty devices if recovery
5800          * isn't possible.
5801          */
5802         if (!test_bit(Faulty, &rdev->flags) &&
5803             mddev->recovery_disabled != conf->recovery_disabled &&
5804             !has_failed(conf) &&
5805             (!p->replacement || p->replacement == rdev) &&
5806             number < conf->raid_disks) {
5807                 err = -EBUSY;
5808                 goto abort;
5809         }
5810         *rdevp = NULL;
5811         synchronize_rcu();
5812         if (atomic_read(&rdev->nr_pending)) {
5813                 /* lost the race, try later */
5814                 err = -EBUSY;
5815                 *rdevp = rdev;
5816         } else if (p->replacement) {
5817                 /* We must have just cleared 'rdev' */
5818                 p->rdev = p->replacement;
5819                 clear_bit(Replacement, &p->replacement->flags);
5820                 smp_mb(); /* Make sure other CPUs may see both as identical
5821                            * but will never see neither - if they are careful
5822                            */
5823                 p->replacement = NULL;
5824                 clear_bit(WantReplacement, &rdev->flags);
5825         } else
5826                 /* We might have just removed the Replacement as faulty-
5827                  * clear the bit just in case
5828                  */
5829                 clear_bit(WantReplacement, &rdev->flags);
5830 abort:
5831
5832         print_raid5_conf(conf);
5833         return err;
5834 }
5835
5836 static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
5837 {
5838         struct r5conf *conf = mddev->private;
5839         int err = -EEXIST;
5840         int disk;
5841         struct disk_info *p;
5842         int first = 0;
5843         int last = conf->raid_disks - 1;
5844
5845         if (mddev->recovery_disabled == conf->recovery_disabled)
5846                 return -EBUSY;
5847
5848         if (rdev->saved_raid_disk < 0 && has_failed(conf))
5849                 /* no point adding a device */
5850                 return -EINVAL;
5851
5852         if (rdev->raid_disk >= 0)
5853                 first = last = rdev->raid_disk;
5854
5855         /*
5856          * find the disk ... but prefer rdev->saved_raid_disk
5857          * if possible.
5858          */
5859         if (rdev->saved_raid_disk >= 0 &&
5860             rdev->saved_raid_disk >= first &&
5861             conf->disks[rdev->saved_raid_disk].rdev == NULL)
5862                 first = rdev->saved_raid_disk;
5863
5864         for (disk = first; disk <= last; disk++) {
5865                 p = conf->disks + disk;
5866                 if (p->rdev == NULL) {
5867                         clear_bit(In_sync, &rdev->flags);
5868                         rdev->raid_disk = disk;
5869                         err = 0;
5870                         if (rdev->saved_raid_disk != disk)
5871                                 conf->fullsync = 1;
5872                         rcu_assign_pointer(p->rdev, rdev);
5873                         goto out;
5874                 }
5875         }
5876         for (disk = first; disk <= last; disk++) {
5877                 p = conf->disks + disk;
5878                 if (test_bit(WantReplacement, &p->rdev->flags) &&
5879                     p->replacement == NULL) {
5880                         clear_bit(In_sync, &rdev->flags);
5881                         set_bit(Replacement, &rdev->flags);
5882                         rdev->raid_disk = disk;
5883                         err = 0;
5884                         conf->fullsync = 1;
5885                         rcu_assign_pointer(p->replacement, rdev);
5886                         break;
5887                 }
5888         }
5889 out:
5890         print_raid5_conf(conf);
5891         return err;
5892 }
5893
5894 static int raid5_resize(struct mddev *mddev, sector_t sectors)
5895 {
5896         /* no resync is happening, and there is enough space
5897          * on all devices, so we can resize.
5898          * We need to make sure resync covers any new space.
5899          * If the array is shrinking we should possibly wait until
5900          * any io in the removed space completes, but it hardly seems
5901          * worth it.
5902          */
5903         sector_t newsize;
5904         sectors &= ~((sector_t)mddev->chunk_sectors - 1);
5905         newsize = raid5_size(mddev, sectors, mddev->raid_disks);
5906         if (mddev->external_size &&
5907             mddev->array_sectors > newsize)
5908                 return -EINVAL;
5909         if (mddev->bitmap) {
5910                 int ret = bitmap_resize(mddev->bitmap, sectors, 0, 0);
5911                 if (ret)
5912                         return ret;
5913         }
5914         md_set_array_sectors(mddev, newsize);
5915         set_capacity(mddev->gendisk, mddev->array_sectors);
5916         revalidate_disk(mddev->gendisk);
5917         if (sectors > mddev->dev_sectors &&
5918             mddev->recovery_cp > mddev->dev_sectors) {
5919                 mddev->recovery_cp = mddev->dev_sectors;
5920                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
5921         }
5922         mddev->dev_sectors = sectors;
5923         mddev->resync_max_sectors = sectors;
5924         return 0;
5925 }
5926
5927 static int check_stripe_cache(struct mddev *mddev)
5928 {
5929         /* Can only proceed if there are plenty of stripe_heads.
5930          * We need a minimum of one full stripe,, and for sensible progress
5931          * it is best to have about 4 times that.
5932          * If we require 4 times, then the default 256 4K stripe_heads will
5933          * allow for chunk sizes up to 256K, which is probably OK.
5934          * If the chunk size is greater, user-space should request more
5935          * stripe_heads first.
5936          */
5937         struct r5conf *conf = mddev->private;
5938         if (((mddev->chunk_sectors << 9) / STRIPE_SIZE) * 4
5939             > conf->max_nr_stripes ||
5940             ((mddev->new_chunk_sectors << 9) / STRIPE_SIZE) * 4
5941             > conf->max_nr_stripes) {
5942                 printk(KERN_WARNING "md/raid:%s: reshape: not enough stripes.  Needed %lu\n",
5943                        mdname(mddev),
5944                        ((max(mddev->chunk_sectors, mddev->new_chunk_sectors) << 9)
5945                         / STRIPE_SIZE)*4);
5946                 return 0;
5947         }
5948         return 1;
5949 }
5950
5951 static int check_reshape(struct mddev *mddev)
5952 {
5953         struct r5conf *conf = mddev->private;
5954
5955         if (mddev->delta_disks == 0 &&
5956             mddev->new_layout == mddev->layout &&
5957             mddev->new_chunk_sectors == mddev->chunk_sectors)
5958                 return 0; /* nothing to do */
5959         if (has_failed(conf))
5960                 return -EINVAL;
5961         if (mddev->delta_disks < 0) {
5962                 /* We might be able to shrink, but the devices must
5963                  * be made bigger first.
5964                  * For raid6, 4 is the minimum size.
5965                  * Otherwise 2 is the minimum
5966                  */
5967                 int min = 2;
5968                 if (mddev->level == 6)
5969                         min = 4;
5970                 if (mddev->raid_disks + mddev->delta_disks < min)
5971                         return -EINVAL;
5972         }
5973
5974         if (!check_stripe_cache(mddev))
5975                 return -ENOSPC;
5976
5977         return resize_stripes(conf, (conf->previous_raid_disks
5978                                      + mddev->delta_disks));
5979 }
5980
5981 static int raid5_start_reshape(struct mddev *mddev)
5982 {
5983         struct r5conf *conf = mddev->private;
5984         struct md_rdev *rdev;
5985         int spares = 0;
5986         unsigned long flags;
5987
5988         if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
5989                 return -EBUSY;
5990
5991         if (!check_stripe_cache(mddev))
5992                 return -ENOSPC;
5993
5994         if (has_failed(conf))
5995                 return -EINVAL;
5996
5997         rdev_for_each(rdev, mddev) {
5998                 if (!test_bit(In_sync, &rdev->flags)
5999                     && !test_bit(Faulty, &rdev->flags))
6000                         spares++;
6001         }
6002
6003         if (spares - mddev->degraded < mddev->delta_disks - conf->max_degraded)
6004                 /* Not enough devices even to make a degraded array
6005                  * of that size
6006                  */
6007                 return -EINVAL;
6008
6009         /* Refuse to reduce size of the array.  Any reductions in
6010          * array size must be through explicit setting of array_size
6011          * attribute.
6012          */
6013         if (raid5_size(mddev, 0, conf->raid_disks + mddev->delta_disks)
6014             < mddev->array_sectors) {
6015                 printk(KERN_ERR "md/raid:%s: array size must be reduced "
6016                        "before number of disks\n", mdname(mddev));
6017                 return -EINVAL;
6018         }
6019
6020         atomic_set(&conf->reshape_stripes, 0);
6021         spin_lock_irq(&conf->device_lock);
6022         conf->previous_raid_disks = conf->raid_disks;
6023         conf->raid_disks += mddev->delta_disks;
6024         conf->prev_chunk_sectors = conf->chunk_sectors;
6025         conf->chunk_sectors = mddev->new_chunk_sectors;
6026         conf->prev_algo = conf->algorithm;
6027         conf->algorithm = mddev->new_layout;
6028         conf->generation++;
6029         /* Code that selects data_offset needs to see the generation update
6030          * if reshape_progress has been set - so a memory barrier needed.
6031          */
6032         smp_mb();
6033         if (mddev->reshape_backwards)
6034                 conf->reshape_progress = raid5_size(mddev, 0, 0);
6035         else
6036                 conf->reshape_progress = 0;
6037         conf->reshape_safe = conf->reshape_progress;
6038         spin_unlock_irq(&conf->device_lock);
6039
6040         /* Add some new drives, as many as will fit.
6041          * We know there are enough to make the newly sized array work.
6042          * Don't add devices if we are reducing the number of
6043          * devices in the array.  This is because it is not possible
6044          * to correctly record the "partially reconstructed" state of
6045          * such devices during the reshape and confusion could result.
6046          */
6047         if (mddev->delta_disks >= 0) {
6048                 rdev_for_each(rdev, mddev)
6049                         if (rdev->raid_disk < 0 &&
6050                             !test_bit(Faulty, &rdev->flags)) {
6051                                 if (raid5_add_disk(mddev, rdev) == 0) {
6052                                         if (rdev->raid_disk
6053                                             >= conf->previous_raid_disks)
6054                                                 set_bit(In_sync, &rdev->flags);
6055                                         else
6056                                                 rdev->recovery_offset = 0;
6057
6058                                         if (sysfs_link_rdev(mddev, rdev))
6059                                                 /* Failure here is OK */;
6060                                 }
6061                         } else if (rdev->raid_disk >= conf->previous_raid_disks
6062                                    && !test_bit(Faulty, &rdev->flags)) {
6063                                 /* This is a spare that was manually added */
6064                                 set_bit(In_sync, &rdev->flags);
6065                         }
6066
6067                 /* When a reshape changes the number of devices,
6068                  * ->degraded is measured against the larger of the
6069                  * pre and post number of devices.
6070                  */
6071                 spin_lock_irqsave(&conf->device_lock, flags);
6072                 mddev->degraded = calc_degraded(conf);
6073                 spin_unlock_irqrestore(&conf->device_lock, flags);
6074         }
6075         mddev->raid_disks = conf->raid_disks;
6076         mddev->reshape_position = conf->reshape_progress;
6077         set_bit(MD_CHANGE_DEVS, &mddev->flags);
6078
6079         clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
6080         clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
6081         set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
6082         set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
6083         mddev->sync_thread = md_register_thread(md_do_sync, mddev,
6084                                                 "reshape");
6085         if (!mddev->sync_thread) {
6086                 mddev->recovery = 0;
6087                 spin_lock_irq(&conf->device_lock);
6088                 mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
6089                 rdev_for_each(rdev, mddev)
6090                         rdev->new_data_offset = rdev->data_offset;
6091                 smp_wmb();
6092                 conf->reshape_progress = MaxSector;
6093                 mddev->reshape_position = MaxSector;
6094                 spin_unlock_irq(&conf->device_lock);
6095                 return -EAGAIN;
6096         }
6097         conf->reshape_checkpoint = jiffies;
6098         md_wakeup_thread(mddev->sync_thread);
6099         md_new_event(mddev);
6100         return 0;
6101 }
6102
6103 /* This is called from the reshape thread and should make any
6104  * changes needed in 'conf'
6105  */
6106 static void end_reshape(struct r5conf *conf)
6107 {
6108
6109         if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
6110                 struct md_rdev *rdev;
6111
6112                 spin_lock_irq(&conf->device_lock);
6113                 conf->previous_raid_disks = conf->raid_disks;
6114                 rdev_for_each(rdev, conf->mddev)
6115                         rdev->data_offset = rdev->new_data_offset;
6116                 smp_wmb();
6117                 conf->reshape_progress = MaxSector;
6118                 spin_unlock_irq(&conf->device_lock);
6119                 wake_up(&conf->wait_for_overlap);
6120
6121                 /* read-ahead size must cover two whole stripes, which is
6122                  * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
6123                  */
6124                 if (conf->mddev->queue) {
6125                         int data_disks = conf->raid_disks - conf->max_degraded;
6126                         int stripe = data_disks * ((conf->chunk_sectors << 9)
6127                                                    / PAGE_SIZE);
6128                         if (conf->mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
6129                                 conf->mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
6130                 }
6131         }
6132 }
6133
6134 /* This is called from the raid5d thread with mddev_lock held.
6135  * It makes config changes to the device.
6136  */
6137 static void raid5_finish_reshape(struct mddev *mddev)
6138 {
6139         struct r5conf *conf = mddev->private;
6140
6141         if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
6142
6143                 if (mddev->delta_disks > 0) {
6144                         md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
6145                         set_capacity(mddev->gendisk, mddev->array_sectors);
6146                         revalidate_disk(mddev->gendisk);
6147                 } else {
6148                         int d;
6149                         spin_lock_irq(&conf->device_lock);
6150                         mddev->degraded = calc_degraded(conf);
6151                         spin_unlock_irq(&conf->device_lock);
6152                         for (d = conf->raid_disks ;
6153                              d < conf->raid_disks - mddev->delta_disks;
6154                              d++) {
6155                                 struct md_rdev *rdev = conf->disks[d].rdev;
6156                                 if (rdev)
6157                                         clear_bit(In_sync, &rdev->flags);
6158                                 rdev = conf->disks[d].replacement;
6159                                 if (rdev)
6160                                         clear_bit(In_sync, &rdev->flags);
6161                         }
6162                 }
6163                 mddev->layout = conf->algorithm;
6164                 mddev->chunk_sectors = conf->chunk_sectors;
6165                 mddev->reshape_position = MaxSector;
6166                 mddev->delta_disks = 0;
6167                 mddev->reshape_backwards = 0;
6168         }
6169 }
6170
6171 static void raid5_quiesce(struct mddev *mddev, int state)
6172 {
6173         struct r5conf *conf = mddev->private;
6174
6175         switch(state) {
6176         case 2: /* resume for a suspend */
6177                 wake_up(&conf->wait_for_overlap);
6178                 break;
6179
6180         case 1: /* stop all writes */
6181                 spin_lock_irq(&conf->device_lock);
6182                 /* '2' tells resync/reshape to pause so that all
6183                  * active stripes can drain
6184                  */
6185                 conf->quiesce = 2;
6186                 wait_event_lock_irq(conf->wait_for_stripe,
6187                                     atomic_read(&conf->active_stripes) == 0 &&
6188                                     atomic_read(&conf->active_aligned_reads) == 0,
6189                                     conf->device_lock);
6190                 conf->quiesce = 1;
6191                 spin_unlock_irq(&conf->device_lock);
6192                 /* allow reshape to continue */
6193                 wake_up(&conf->wait_for_overlap);
6194                 break;
6195
6196         case 0: /* re-enable writes */
6197                 spin_lock_irq(&conf->device_lock);
6198                 conf->quiesce = 0;
6199                 wake_up(&conf->wait_for_stripe);
6200                 wake_up(&conf->wait_for_overlap);
6201                 spin_unlock_irq(&conf->device_lock);
6202                 break;
6203         }
6204 }
6205
6206
6207 static void *raid45_takeover_raid0(struct mddev *mddev, int level)
6208 {
6209         struct r0conf *raid0_conf = mddev->private;
6210         sector_t sectors;
6211
6212         /* for raid0 takeover only one zone is supported */
6213         if (raid0_conf->nr_strip_zones > 1) {
6214                 printk(KERN_ERR "md/raid:%s: cannot takeover raid0 with more than one zone.\n",
6215                        mdname(mddev));
6216                 return ERR_PTR(-EINVAL);
6217         }
6218
6219         sectors = raid0_conf->strip_zone[0].zone_end;
6220         sector_div(sectors, raid0_conf->strip_zone[0].nb_dev);
6221         mddev->dev_sectors = sectors;
6222         mddev->new_level = level;
6223         mddev->new_layout = ALGORITHM_PARITY_N;
6224         mddev->new_chunk_sectors = mddev->chunk_sectors;
6225         mddev->raid_disks += 1;
6226         mddev->delta_disks = 1;
6227         /* make sure it will be not marked as dirty */
6228         mddev->recovery_cp = MaxSector;
6229
6230         return setup_conf(mddev);
6231 }
6232
6233
6234 static void *raid5_takeover_raid1(struct mddev *mddev)
6235 {
6236         int chunksect;
6237
6238         if (mddev->raid_disks != 2 ||
6239             mddev->degraded > 1)
6240                 return ERR_PTR(-EINVAL);
6241
6242         /* Should check if there are write-behind devices? */
6243
6244         chunksect = 64*2; /* 64K by default */
6245
6246         /* The array must be an exact multiple of chunksize */
6247         while (chunksect && (mddev->array_sectors & (chunksect-1)))
6248                 chunksect >>= 1;
6249
6250         if ((chunksect<<9) < STRIPE_SIZE)
6251                 /* array size does not allow a suitable chunk size */
6252                 return ERR_PTR(-EINVAL);
6253
6254         mddev->new_level = 5;
6255         mddev->new_layout = ALGORITHM_LEFT_SYMMETRIC;
6256         mddev->new_chunk_sectors = chunksect;
6257
6258         return setup_conf(mddev);
6259 }
6260
6261 static void *raid5_takeover_raid6(struct mddev *mddev)
6262 {
6263         int new_layout;
6264
6265         switch (mddev->layout) {
6266         case ALGORITHM_LEFT_ASYMMETRIC_6:
6267                 new_layout = ALGORITHM_LEFT_ASYMMETRIC;
6268                 break;
6269         case ALGORITHM_RIGHT_ASYMMETRIC_6:
6270                 new_layout = ALGORITHM_RIGHT_ASYMMETRIC;
6271                 break;
6272         case ALGORITHM_LEFT_SYMMETRIC_6:
6273                 new_layout = ALGORITHM_LEFT_SYMMETRIC;
6274                 break;
6275         case ALGORITHM_RIGHT_SYMMETRIC_6:
6276                 new_layout = ALGORITHM_RIGHT_SYMMETRIC;
6277                 break;
6278         case ALGORITHM_PARITY_0_6:
6279                 new_layout = ALGORITHM_PARITY_0;
6280                 break;
6281         case ALGORITHM_PARITY_N:
6282                 new_layout = ALGORITHM_PARITY_N;
6283                 break;
6284         default:
6285                 return ERR_PTR(-EINVAL);
6286         }
6287         mddev->new_level = 5;
6288         mddev->new_layout = new_layout;
6289         mddev->delta_disks = -1;
6290         mddev->raid_disks -= 1;
6291         return setup_conf(mddev);
6292 }
6293
6294
6295 static int raid5_check_reshape(struct mddev *mddev)
6296 {
6297         /* For a 2-drive array, the layout and chunk size can be changed
6298          * immediately as not restriping is needed.
6299          * For larger arrays we record the new value - after validation
6300          * to be used by a reshape pass.
6301          */
6302         struct r5conf *conf = mddev->private;
6303         int new_chunk = mddev->new_chunk_sectors;
6304
6305         if (mddev->new_layout >= 0 && !algorithm_valid_raid5(mddev->new_layout))
6306                 return -EINVAL;
6307         if (new_chunk > 0) {
6308                 if (!is_power_of_2(new_chunk))
6309                         return -EINVAL;
6310                 if (new_chunk < (PAGE_SIZE>>9))
6311                         return -EINVAL;
6312                 if (mddev->array_sectors & (new_chunk-1))
6313                         /* not factor of array size */
6314                         return -EINVAL;
6315         }
6316
6317         /* They look valid */
6318
6319         if (mddev->raid_disks == 2) {
6320                 /* can make the change immediately */
6321                 if (mddev->new_layout >= 0) {
6322                         conf->algorithm = mddev->new_layout;
6323                         mddev->layout = mddev->new_layout;
6324                 }
6325                 if (new_chunk > 0) {
6326                         conf->chunk_sectors = new_chunk ;
6327                         mddev->chunk_sectors = new_chunk;
6328                 }
6329                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
6330                 md_wakeup_thread(mddev->thread);
6331         }
6332         return check_reshape(mddev);
6333 }
6334
6335 static int raid6_check_reshape(struct mddev *mddev)
6336 {
6337         int new_chunk = mddev->new_chunk_sectors;
6338
6339         if (mddev->new_layout >= 0 && !algorithm_valid_raid6(mddev->new_layout))
6340                 return -EINVAL;
6341         if (new_chunk > 0) {
6342                 if (!is_power_of_2(new_chunk))
6343                         return -EINVAL;
6344                 if (new_chunk < (PAGE_SIZE >> 9))
6345                         return -EINVAL;
6346                 if (mddev->array_sectors & (new_chunk-1))
6347                         /* not factor of array size */
6348                         return -EINVAL;
6349         }
6350
6351         /* They look valid */
6352         return check_reshape(mddev);
6353 }
6354
6355 static void *raid5_takeover(struct mddev *mddev)
6356 {
6357         /* raid5 can take over:
6358          *  raid0 - if there is only one strip zone - make it a raid4 layout
6359          *  raid1 - if there are two drives.  We need to know the chunk size
6360          *  raid4 - trivial - just use a raid4 layout.
6361          *  raid6 - Providing it is a *_6 layout
6362          */
6363         if (mddev->level == 0)
6364                 return raid45_takeover_raid0(mddev, 5);
6365         if (mddev->level == 1)
6366                 return raid5_takeover_raid1(mddev);
6367         if (mddev->level == 4) {
6368                 mddev->new_layout = ALGORITHM_PARITY_N;
6369                 mddev->new_level = 5;
6370                 return setup_conf(mddev);
6371         }
6372         if (mddev->level == 6)
6373                 return raid5_takeover_raid6(mddev);
6374
6375         return ERR_PTR(-EINVAL);
6376 }
6377
6378 static void *raid4_takeover(struct mddev *mddev)
6379 {
6380         /* raid4 can take over:
6381          *  raid0 - if there is only one strip zone
6382          *  raid5 - if layout is right
6383          */
6384         if (mddev->level == 0)
6385                 return raid45_takeover_raid0(mddev, 4);
6386         if (mddev->level == 5 &&
6387             mddev->layout == ALGORITHM_PARITY_N) {
6388                 mddev->new_layout = 0;
6389                 mddev->new_level = 4;
6390                 return setup_conf(mddev);
6391         }
6392         return ERR_PTR(-EINVAL);
6393 }
6394
6395 static struct md_personality raid5_personality;
6396
6397 static void *raid6_takeover(struct mddev *mddev)
6398 {
6399         /* Currently can only take over a raid5.  We map the
6400          * personality to an equivalent raid6 personality
6401          * with the Q block at the end.
6402          */
6403         int new_layout;
6404
6405         if (mddev->pers != &raid5_personality)
6406                 return ERR_PTR(-EINVAL);
6407         if (mddev->degraded > 1)
6408                 return ERR_PTR(-EINVAL);
6409         if (mddev->raid_disks > 253)
6410                 return ERR_PTR(-EINVAL);
6411         if (mddev->raid_disks < 3)
6412                 return ERR_PTR(-EINVAL);
6413
6414         switch (mddev->layout) {
6415         case ALGORITHM_LEFT_ASYMMETRIC:
6416                 new_layout = ALGORITHM_LEFT_ASYMMETRIC_6;
6417                 break;
6418         case ALGORITHM_RIGHT_ASYMMETRIC:
6419                 new_layout = ALGORITHM_RIGHT_ASYMMETRIC_6;
6420                 break;
6421         case ALGORITHM_LEFT_SYMMETRIC:
6422                 new_layout = ALGORITHM_LEFT_SYMMETRIC_6;
6423                 break;
6424         case ALGORITHM_RIGHT_SYMMETRIC:
6425                 new_layout = ALGORITHM_RIGHT_SYMMETRIC_6;
6426                 break;
6427         case ALGORITHM_PARITY_0:
6428                 new_layout = ALGORITHM_PARITY_0_6;
6429                 break;
6430         case ALGORITHM_PARITY_N:
6431                 new_layout = ALGORITHM_PARITY_N;
6432                 break;
6433         default:
6434                 return ERR_PTR(-EINVAL);
6435         }
6436         mddev->new_level = 6;
6437         mddev->new_layout = new_layout;
6438         mddev->delta_disks = 1;
6439         mddev->raid_disks += 1;
6440         return setup_conf(mddev);
6441 }
6442
6443
6444 static struct md_personality raid6_personality =
6445 {
6446         .name           = "raid6",
6447         .level          = 6,
6448         .owner          = THIS_MODULE,
6449         .make_request   = make_request,
6450         .run            = run,
6451         .stop           = stop,
6452         .status         = status,
6453         .error_handler  = error,
6454         .hot_add_disk   = raid5_add_disk,
6455         .hot_remove_disk= raid5_remove_disk,
6456         .spare_active   = raid5_spare_active,
6457         .sync_request   = sync_request,
6458         .resize         = raid5_resize,
6459         .size           = raid5_size,
6460         .check_reshape  = raid6_check_reshape,
6461         .start_reshape  = raid5_start_reshape,
6462         .finish_reshape = raid5_finish_reshape,
6463         .quiesce        = raid5_quiesce,
6464         .takeover       = raid6_takeover,
6465 };
6466 static struct md_personality raid5_personality =
6467 {
6468         .name           = "raid5",
6469         .level          = 5,
6470         .owner          = THIS_MODULE,
6471         .make_request   = make_request,
6472         .run            = run,
6473         .stop           = stop,
6474         .status         = status,
6475         .error_handler  = error,
6476         .hot_add_disk   = raid5_add_disk,
6477         .hot_remove_disk= raid5_remove_disk,
6478         .spare_active   = raid5_spare_active,
6479         .sync_request   = sync_request,
6480         .resize         = raid5_resize,
6481         .size           = raid5_size,
6482         .check_reshape  = raid5_check_reshape,
6483         .start_reshape  = raid5_start_reshape,
6484         .finish_reshape = raid5_finish_reshape,
6485         .quiesce        = raid5_quiesce,
6486         .takeover       = raid5_takeover,
6487 };
6488
6489 static struct md_personality raid4_personality =
6490 {
6491         .name           = "raid4",
6492         .level          = 4,
6493         .owner          = THIS_MODULE,
6494         .make_request   = make_request,
6495         .run            = run,
6496         .stop           = stop,
6497         .status         = status,
6498         .error_handler  = error,
6499         .hot_add_disk   = raid5_add_disk,
6500         .hot_remove_disk= raid5_remove_disk,
6501         .spare_active   = raid5_spare_active,
6502         .sync_request   = sync_request,
6503         .resize         = raid5_resize,
6504         .size           = raid5_size,
6505         .check_reshape  = raid5_check_reshape,
6506         .start_reshape  = raid5_start_reshape,
6507         .finish_reshape = raid5_finish_reshape,
6508         .quiesce        = raid5_quiesce,
6509         .takeover       = raid4_takeover,
6510 };
6511
6512 static int __init raid5_init(void)
6513 {
6514         register_md_personality(&raid6_personality);
6515         register_md_personality(&raid5_personality);
6516         register_md_personality(&raid4_personality);
6517         return 0;
6518 }
6519
6520 static void raid5_exit(void)
6521 {
6522         unregister_md_personality(&raid6_personality);
6523         unregister_md_personality(&raid5_personality);
6524         unregister_md_personality(&raid4_personality);
6525 }
6526
6527 module_init(raid5_init);
6528 module_exit(raid5_exit);
6529 MODULE_LICENSE("GPL");
6530 MODULE_DESCRIPTION("RAID4/5/6 (striping with parity) personality for MD");
6531 MODULE_ALIAS("md-personality-4"); /* RAID5 */
6532 MODULE_ALIAS("md-raid5");
6533 MODULE_ALIAS("md-raid4");
6534 MODULE_ALIAS("md-level-5");
6535 MODULE_ALIAS("md-level-4");
6536 MODULE_ALIAS("md-personality-8"); /* RAID6 */
6537 MODULE_ALIAS("md-raid6");
6538 MODULE_ALIAS("md-level-6");
6539
6540 /* This used to be two separate modules, they were: */
6541 MODULE_ALIAS("raid5");
6542 MODULE_ALIAS("raid6");