drivers/md/dm-region-hash.c

   1 /*
   2  * Copyright (C) 2003 Sistina Software Limited.
   3  * Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
   4  *
   5  * This file is released under the GPL.
   6  */
   7
   8 #include <linux/dm-dirty-log.h>
   9 #include <linux/dm-region-hash.h>
  10
  11 #include <linux/ctype.h>
  12 #include <linux/init.h>
  13 #include <linux/module.h>
  14 #include <linux/slab.h>
  15 #include <linux/vmalloc.h>
  16
  17 #include "dm.h"
  18
  19 #define DM_MSG_PREFIX   "region hash"
  20
  21 /*-----------------------------------------------------------------
  22  * Region hash
  23  *
  24  * The mirror splits itself up into discrete regions.  Each
  25  * region can be in one of three states: clean, dirty,
  26  * nosync.  There is no need to put clean regions in the hash.
  27  *
  28  * In addition to being present in the hash table a region _may_
  29  * be present on one of three lists.
  30  *
  31  *   clean_regions: Regions on this list have no io pending to
  32  *   them, they are in sync, we are no longer interested in them,
  33  *   they are dull.  dm_rh_update_states() will remove them from the
  34  *   hash table.
  35  *
  36  *   quiesced_regions: These regions have been spun down, ready
  37  *   for recovery.  rh_recovery_start() will remove regions from
  38  *   this list and hand them to kmirrord, which will schedule the
  39  *   recovery io with kcopyd.
  40  *
  41  *   recovered_regions: Regions that kcopyd has successfully
  42  *   recovered.  dm_rh_update_states() will now schedule any delayed
  43  *   io, up the recovery_count, and remove the region from the
  44  *   hash.
  45  *
  46  * There are 2 locks:
  47  *   A rw spin lock 'hash_lock' protects just the hash table,
  48  *   this is never held in write mode from interrupt context,
  49  *   which I believe means that we only have to disable irqs when
  50  *   doing a write lock.
  51  *
  52  *   An ordinary spin lock 'region_lock' that protects the three
  53  *   lists in the region_hash, with the 'state', 'list' and
  54  *   'delayed_bios' fields of the regions.  This is used from irq
  55  *   context, so all other uses will have to suspend local irqs.
  56  *---------------------------------------------------------------*/
  57 struct dm_region_hash {
  58         uint32_t region_size;
  59         unsigned region_shift;
  60
  61         /* holds persistent region state */
  62         struct dm_dirty_log *log;
  63
  64         /* hash table */
  65         rwlock_t hash_lock;
  66         mempool_t *region_pool;
  67         unsigned mask;
  68         unsigned nr_buckets;
  69         unsigned prime;
  70         unsigned shift;
  71         struct list_head *buckets;
  72
  73         unsigned max_recovery; /* Max # of regions to recover in parallel */
  74
  75         spinlock_t region_lock;
  76         atomic_t recovery_in_flight;
  77         struct semaphore recovery_count;
  78         struct list_head clean_regions;
  79         struct list_head quiesced_regions;
  80         struct list_head recovered_regions;
  81         struct list_head failed_recovered_regions;
  82
  83         /*
  84          * If there was a flush failure no regions can be marked clean.
  85          */
  86         int flush_failure;
  87
  88         void *context;
  89         sector_t target_begin;
  90
  91         /* Callback function to schedule bios writes */
  92         void (*dispatch_bios)(void *context, struct bio_list *bios);
  93
  94         /* Callback function to wakeup callers worker thread. */
  95         void (*wakeup_workers)(void *context);
  96
  97         /* Callback function to wakeup callers recovery waiters. */
  98         void (*wakeup_all_recovery_waiters)(void *context);
  99 };
 100
 101 struct dm_region {
 102         struct dm_region_hash *rh;      /* FIXME: can we get rid of this ? */
 103         region_t key;
 104         int state;
 105
 106         struct list_head hash_list;
 107         struct list_head list;
 108
 109         atomic_t pending;
 110         struct bio_list delayed_bios;
 111 };
 112
 113 /*
 114  * Conversion fns
 115  */
 116 static region_t dm_rh_sector_to_region(struct dm_region_hash *rh, sector_t sector)
 117 {
 118         return sector >> rh->region_shift;
 119 }
 120
 121 sector_t dm_rh_region_to_sector(struct dm_region_hash *rh, region_t region)
 122 {
 123         return region << rh->region_shift;
 124 }
 125 EXPORT_SYMBOL_GPL(dm_rh_region_to_sector);
 126
 127 region_t dm_rh_bio_to_region(struct dm_region_hash *rh, struct bio *bio)
 128 {
 129         return dm_rh_sector_to_region(rh, bio->bi_iter.bi_sector -
 130                                       rh->target_begin);
 131 }
 132 EXPORT_SYMBOL_GPL(dm_rh_bio_to_region);
 133
 134 void *dm_rh_region_context(struct dm_region *reg)
 135 {
 136         return reg->rh->context;
 137 }
 138 EXPORT_SYMBOL_GPL(dm_rh_region_context);
 139
 140 region_t dm_rh_get_region_key(struct dm_region *reg)
 141 {
 142         return reg->key;
 143 }
 144 EXPORT_SYMBOL_GPL(dm_rh_get_region_key);
 145
 146 sector_t dm_rh_get_region_size(struct dm_region_hash *rh)
 147 {
 148         return rh->region_size;
 149 }
 150 EXPORT_SYMBOL_GPL(dm_rh_get_region_size);
 151
 152 /*
 153  * FIXME: shall we pass in a structure instead of all these args to
 154  * dm_region_hash_create()????
 155  */
 156 #define RH_HASH_MULT 2654435387U
 157 #define RH_HASH_SHIFT 12
 158
 159 #define MIN_REGIONS 64
 160 struct dm_region_hash *dm_region_hash_create(
 161                 void *context, void (*dispatch_bios)(void *context,
 162                                                      struct bio_list *bios),
 163                 void (*wakeup_workers)(void *context),
 164                 void (*wakeup_all_recovery_waiters)(void *context),
 165                 sector_t target_begin, unsigned max_recovery,
 166                 struct dm_dirty_log *log, uint32_t region_size,
 167                 region_t nr_regions)
 168 {
 169         struct dm_region_hash *rh;
 170         unsigned nr_buckets, max_buckets;
 171         size_t i;
 172
 173         /*
 174          * Calculate a suitable number of buckets for our hash
 175          * table.
 176          */
 177         max_buckets = nr_regions >> 6;
 178         for (nr_buckets = 128u; nr_buckets < max_buckets; nr_buckets <<= 1)
 179                 ;
 180         nr_buckets >>= 1;
 181
 182         rh = kmalloc(sizeof(*rh), GFP_KERNEL);
 183         if (!rh) {
 184                 DMERR("unable to allocate region hash memory");
 185                 return ERR_PTR(-ENOMEM);
 186         }
 187
 188         rh->context = context;
 189         rh->dispatch_bios = dispatch_bios;
 190         rh->wakeup_workers = wakeup_workers;
 191         rh->wakeup_all_recovery_waiters = wakeup_all_recovery_waiters;
 192         rh->target_begin = target_begin;
 193         rh->max_recovery = max_recovery;
 194         rh->log = log;
 195         rh->region_size = region_size;
 196         rh->region_shift = ffs(region_size) - 1;
 197         rwlock_init(&rh->hash_lock);
 198         rh->mask = nr_buckets - 1;
 199         rh->nr_buckets = nr_buckets;
 200
 201         rh->shift = RH_HASH_SHIFT;
 202         rh->prime = RH_HASH_MULT;
 203
 204         rh->buckets = vmalloc(nr_buckets * sizeof(*rh->buckets));
 205         if (!rh->buckets) {
 206                 DMERR("unable to allocate region hash bucket memory");
 207                 kfree(rh);
 208                 return ERR_PTR(-ENOMEM);
 209         }
 210
 211         for (i = 0; i < nr_buckets; i++)
 212                 INIT_LIST_HEAD(rh->buckets + i);
 213
 214         spin_lock_init(&rh->region_lock);
 215         sema_init(&rh->recovery_count, 0);
 216         atomic_set(&rh->recovery_in_flight, 0);
 217         INIT_LIST_HEAD(&rh->clean_regions);
 218         INIT_LIST_HEAD(&rh->quiesced_regions);
 219         INIT_LIST_HEAD(&rh->recovered_regions);
 220         INIT_LIST_HEAD(&rh->failed_recovered_regions);
 221         rh->flush_failure = 0;
 222
 223         rh->region_pool = mempool_create_kmalloc_pool(MIN_REGIONS,
 224                                                       sizeof(struct dm_region));
 225         if (!rh->region_pool) {
 226                 vfree(rh->buckets);
 227                 kfree(rh);
 228                 rh = ERR_PTR(-ENOMEM);
 229         }
 230
 231         return rh;
 232 }
 233 EXPORT_SYMBOL_GPL(dm_region_hash_create);
 234
 235 void dm_region_hash_destroy(struct dm_region_hash *rh)
 236 {
 237         unsigned h;
 238         struct dm_region *reg, *nreg;
 239
 240         BUG_ON(!list_empty(&rh->quiesced_regions));
 241         for (h = 0; h < rh->nr_buckets; h++) {
 242                 list_for_each_entry_safe(reg, nreg, rh->buckets + h,
 243                                          hash_list) {
 244                         BUG_ON(atomic_read(&reg->pending));
 245                         mempool_free(reg, rh->region_pool);
 246                 }
 247         }
 248
 249         if (rh->log)
 250                 dm_dirty_log_destroy(rh->log);
 251
 252         if (rh->region_pool)
 253                 mempool_destroy(rh->region_pool);
 254
 255         vfree(rh->buckets);
 256         kfree(rh);
 257 }
 258 EXPORT_SYMBOL_GPL(dm_region_hash_destroy);
 259
 260 struct dm_dirty_log *dm_rh_dirty_log(struct dm_region_hash *rh)
 261 {
 262         return rh->log;
 263 }
 264 EXPORT_SYMBOL_GPL(dm_rh_dirty_log);
 265
 266 static unsigned rh_hash(struct dm_region_hash *rh, region_t region)
 267 {
 268         return (unsigned) ((region * rh->prime) >> rh->shift) & rh->mask;
 269 }
 270
 271 static struct dm_region *__rh_lookup(struct dm_region_hash *rh, region_t region)
 272 {
 273         struct dm_region *reg;
 274         struct list_head *bucket = rh->buckets + rh_hash(rh, region);
 275
 276         list_for_each_entry(reg, bucket, hash_list)
 277                 if (reg->key == region)
 278                         return reg;
 279
 280         return NULL;
 281 }
 282
 283 static void __rh_insert(struct dm_region_hash *rh, struct dm_region *reg)
 284 {
 285         list_add(&reg->hash_list, rh->buckets + rh_hash(rh, reg->key));
 286 }
 287
 288 static struct dm_region *__rh_alloc(struct dm_region_hash *rh, region_t region)
 289 {
 290         struct dm_region *reg, *nreg;
 291
 292         nreg = mempool_alloc(rh->region_pool, GFP_ATOMIC);
 293         if (unlikely(!nreg))
 294                 nreg = kmalloc(sizeof(*nreg), GFP_NOIO | __GFP_NOFAIL);
 295
 296         nreg->state = rh->log->type->in_sync(rh->log, region, 1) ?
 297                       DM_RH_CLEAN : DM_RH_NOSYNC;
 298         nreg->rh = rh;
 299         nreg->key = region;
 300         INIT_LIST_HEAD(&nreg->list);
 301         atomic_set(&nreg->pending, 0);
 302         bio_list_init(&nreg->delayed_bios);
 303
 304         write_lock_irq(&rh->hash_lock);
 305         reg = __rh_lookup(rh, region);
 306         if (reg)
 307                 /* We lost the race. */
 308                 mempool_free(nreg, rh->region_pool);
 309         else {
 310                 __rh_insert(rh, nreg);
 311                 if (nreg->state == DM_RH_CLEAN) {
 312                         spin_lock(&rh->region_lock);
 313                         list_add(&nreg->list, &rh->clean_regions);
 314                         spin_unlock(&rh->region_lock);
 315                 }
 316
 317                 reg = nreg;
 318         }
 319         write_unlock_irq(&rh->hash_lock);
 320
 321         return reg;
 322 }
 323
 324 static struct dm_region *__rh_find(struct dm_region_hash *rh, region_t region)
 325 {
 326         struct dm_region *reg;
 327
 328         reg = __rh_lookup(rh, region);
 329         if (!reg) {
 330                 read_unlock(&rh->hash_lock);
 331                 reg = __rh_alloc(rh, region);
 332                 read_lock(&rh->hash_lock);
 333         }
 334
 335         return reg;
 336 }
 337
 338 int dm_rh_get_state(struct dm_region_hash *rh, region_t region, int may_block)
 339 {
 340         int r;
 341         struct dm_region *reg;
 342
 343         read_lock(&rh->hash_lock);
 344         reg = __rh_lookup(rh, region);
 345         read_unlock(&rh->hash_lock);
 346
 347         if (reg)
 348                 return reg->state;
 349
 350         /*
 351          * The region wasn't in the hash, so we fall back to the
 352          * dirty log.
 353          */
 354         r = rh->log->type->in_sync(rh->log, region, may_block);
 355
 356         /*
 357          * Any error from the dirty log (eg. -EWOULDBLOCK) gets
 358          * taken as a DM_RH_NOSYNC
 359          */
 360         return r == 1 ? DM_RH_CLEAN : DM_RH_NOSYNC;
 361 }
 362 EXPORT_SYMBOL_GPL(dm_rh_get_state);
 363
 364 static void complete_resync_work(struct dm_region *reg, int success)
 365 {
 366         struct dm_region_hash *rh = reg->rh;
 367
 368         rh->log->type->set_region_sync(rh->log, reg->key, success);
 369
 370         /*
 371          * Dispatch the bios before we call 'wake_up_all'.
 372          * This is important because if we are suspending,
 373          * we want to know that recovery is complete and
 374          * the work queue is flushed.  If we wake_up_all
 375          * before we dispatch_bios (queue bios and call wake()),
 376          * then we risk suspending before the work queue
 377          * has been properly flushed.
 378          */
 379         rh->dispatch_bios(rh->context, &reg->delayed_bios);
 380         if (atomic_dec_and_test(&rh->recovery_in_flight))
 381                 rh->wakeup_all_recovery_waiters(rh->context);
 382         up(&rh->recovery_count);
 383 }
 384
 385 /* dm_rh_mark_nosync
 386  * @ms
 387  * @bio
 388  *
 389  * The bio was written on some mirror(s) but failed on other mirror(s).
 390  * We can successfully endio the bio but should avoid the region being
 391  * marked clean by setting the state DM_RH_NOSYNC.
 392  *
 393  * This function is _not_ safe in interrupt context!
 394  */
 395 void dm_rh_mark_nosync(struct dm_region_hash *rh, struct bio *bio)
 396 {
 397         unsigned long flags;
 398         struct dm_dirty_log *log = rh->log;
 399         struct dm_region *reg;
 400         region_t region = dm_rh_bio_to_region(rh, bio);
 401         int recovering = 0;
 402
 403         if (bio->bi_rw & REQ_FLUSH) {
 404                 rh->flush_failure = 1;
 405                 return;
 406         }
 407
 408         if (bio->bi_rw & REQ_DISCARD)
 409                 return;
 410
 411         /* We must inform the log that the sync count has changed. */
 412         log->type->set_region_sync(log, region, 0);
 413
 414         read_lock(&rh->hash_lock);
 415         reg = __rh_find(rh, region);
 416         read_unlock(&rh->hash_lock);
 417
 418         /* region hash entry should exist because write was in-flight */
 419         BUG_ON(!reg);
 420         BUG_ON(!list_empty(&reg->list));
 421
 422         spin_lock_irqsave(&rh->region_lock, flags);
 423         /*
 424          * Possible cases:
 425          *   1) DM_RH_DIRTY
 426          *   2) DM_RH_NOSYNC: was dirty, other preceding writes failed
 427          *   3) DM_RH_RECOVERING: flushing pending writes
 428          * Either case, the region should have not been connected to list.
 429          */
 430         recovering = (reg->state == DM_RH_RECOVERING);
 431         reg->state = DM_RH_NOSYNC;
 432         BUG_ON(!list_empty(&reg->list));
 433         spin_unlock_irqrestore(&rh->region_lock, flags);
 434
 435         if (recovering)
 436                 complete_resync_work(reg, 0);
 437 }
 438 EXPORT_SYMBOL_GPL(dm_rh_mark_nosync);
 439
 440 void dm_rh_update_states(struct dm_region_hash *rh, int errors_handled)
 441 {
 442         struct dm_region *reg, *next;
 443
 444         LIST_HEAD(clean);
 445         LIST_HEAD(recovered);
 446         LIST_HEAD(failed_recovered);
 447
 448         /*
 449          * Quickly grab the lists.
 450          */
 451         write_lock_irq(&rh->hash_lock);
 452         spin_lock(&rh->region_lock);
 453         if (!list_empty(&rh->clean_regions)) {
 454                 list_splice_init(&rh->clean_regions, &clean);
 455
 456                 list_for_each_entry(reg, &clean, list)
 457                         list_del(&reg->hash_list);
 458         }
 459
 460         if (!list_empty(&rh->recovered_regions)) {
 461                 list_splice_init(&rh->recovered_regions, &recovered);
 462
 463                 list_for_each_entry(reg, &recovered, list)
 464                         list_del(&reg->hash_list);
 465         }
 466
 467         if (!list_empty(&rh->failed_recovered_regions)) {
 468                 list_splice_init(&rh->failed_recovered_regions,
 469                                  &failed_recovered);
 470
 471                 list_for_each_entry(reg, &failed_recovered, list)
 472                         list_del(&reg->hash_list);
 473         }
 474
 475         spin_unlock(&rh->region_lock);
 476         write_unlock_irq(&rh->hash_lock);
 477
 478         /*
 479          * All the regions on the recovered and clean lists have
 480          * now been pulled out of the system, so no need to do
 481          * any more locking.
 482          */
 483         list_for_each_entry_safe(reg, next, &recovered, list) {
 484                 rh->log->type->clear_region(rh->log, reg->key);
 485                 complete_resync_work(reg, 1);
 486                 mempool_free(reg, rh->region_pool);
 487         }
 488
 489         list_for_each_entry_safe(reg, next, &failed_recovered, list) {
 490                 complete_resync_work(reg, errors_handled ? 0 : 1);
 491                 mempool_free(reg, rh->region_pool);
 492         }
 493
 494         list_for_each_entry_safe(reg, next, &clean, list) {
 495                 rh->log->type->clear_region(rh->log, reg->key);
 496                 mempool_free(reg, rh->region_pool);
 497         }
 498
 499         rh->log->type->flush(rh->log);
 500 }
 501 EXPORT_SYMBOL_GPL(dm_rh_update_states);
 502
 503 static void rh_inc(struct dm_region_hash *rh, region_t region)
 504 {
 505         struct dm_region *reg;
 506
 507         read_lock(&rh->hash_lock);
 508         reg = __rh_find(rh, region);
 509
 510         spin_lock_irq(&rh->region_lock);
 511         atomic_inc(&reg->pending);
 512
 513         if (reg->state == DM_RH_CLEAN) {
 514                 reg->state = DM_RH_DIRTY;
 515                 list_del_init(&reg->list);      /* take off the clean list */
 516                 spin_unlock_irq(&rh->region_lock);
 517
 518                 rh->log->type->mark_region(rh->log, reg->key);
 519         } else
 520                 spin_unlock_irq(&rh->region_lock);
 521
 522
 523         read_unlock(&rh->hash_lock);
 524 }
 525
 526 void dm_rh_inc_pending(struct dm_region_hash *rh, struct bio_list *bios)
 527 {
 528         struct bio *bio;
 529
 530         for (bio = bios->head; bio; bio = bio->bi_next) {
 531                 if (bio->bi_rw & (REQ_FLUSH | REQ_DISCARD))
 532                         continue;
 533                 rh_inc(rh, dm_rh_bio_to_region(rh, bio));
 534         }
 535 }
 536 EXPORT_SYMBOL_GPL(dm_rh_inc_pending);
 537
 538 void dm_rh_dec(struct dm_region_hash *rh, region_t region)
 539 {
 540         unsigned long flags;
 541         struct dm_region *reg;
 542         int should_wake = 0;
 543
 544         read_lock(&rh->hash_lock);
 545         reg = __rh_lookup(rh, region);
 546         read_unlock(&rh->hash_lock);
 547
 548         spin_lock_irqsave(&rh->region_lock, flags);
 549         if (atomic_dec_and_test(&reg->pending)) {
 550                 /*
 551                  * There is no pending I/O for this region.
 552                  * We can move the region to corresponding list for next action.
 553                  * At this point, the region is not yet connected to any list.
 554                  *
 555                  * If the state is DM_RH_NOSYNC, the region should be kept off
 556                  * from clean list.
 557                  * The hash entry for DM_RH_NOSYNC will remain in memory
 558                  * until the region is recovered or the map is reloaded.
 559                  */
 560
 561                 /* do nothing for DM_RH_NOSYNC */
 562                 if (unlikely(rh->flush_failure)) {
 563                         /*
 564                          * If a write flush failed some time ago, we
 565                          * don't know whether or not this write made it
 566                          * to the disk, so we must resync the device.
 567                          */
 568                         reg->state = DM_RH_NOSYNC;
 569                 } else if (reg->state == DM_RH_RECOVERING) {
 570                         list_add_tail(&reg->list, &rh->quiesced_regions);
 571                 } else if (reg->state == DM_RH_DIRTY) {
 572                         reg->state = DM_RH_CLEAN;
 573                         list_add(&reg->list, &rh->clean_regions);
 574                 }
 575                 should_wake = 1;
 576         }
 577         spin_unlock_irqrestore(&rh->region_lock, flags);
 578
 579         if (should_wake)
 580                 rh->wakeup_workers(rh->context);
 581 }
 582 EXPORT_SYMBOL_GPL(dm_rh_dec);
 583
 584 /*
 585  * Starts quiescing a region in preparation for recovery.
 586  */
 587 static int __rh_recovery_prepare(struct dm_region_hash *rh)
 588 {
 589         int r;
 590         region_t region;
 591         struct dm_region *reg;
 592
 593         /*
 594          * Ask the dirty log what's next.
 595          */
 596         r = rh->log->type->get_resync_work(rh->log, &region);
 597         if (r <= 0)
 598                 return r;
 599
 600         /*
 601          * Get this region, and start it quiescing by setting the
 602          * recovering flag.
 603          */
 604         read_lock(&rh->hash_lock);
 605         reg = __rh_find(rh, region);
 606         read_unlock(&rh->hash_lock);
 607
 608         spin_lock_irq(&rh->region_lock);
 609         reg->state = DM_RH_RECOVERING;
 610
 611         /* Already quiesced ? */
 612         if (atomic_read(&reg->pending))
 613                 list_del_init(&reg->list);
 614         else
 615                 list_move(&reg->list, &rh->quiesced_regions);
 616
 617         spin_unlock_irq(&rh->region_lock);
 618
 619         return 1;
 620 }
 621
 622 void dm_rh_recovery_prepare(struct dm_region_hash *rh)
 623 {
 624         /* Extra reference to avoid race with dm_rh_stop_recovery */
 625         atomic_inc(&rh->recovery_in_flight);
 626
 627         while (!down_trylock(&rh->recovery_count)) {
 628                 atomic_inc(&rh->recovery_in_flight);
 629                 if (__rh_recovery_prepare(rh) <= 0) {
 630                         atomic_dec(&rh->recovery_in_flight);
 631                         up(&rh->recovery_count);
 632                         break;
 633                 }
 634         }
 635
 636         /* Drop the extra reference */
 637         if (atomic_dec_and_test(&rh->recovery_in_flight))
 638                 rh->wakeup_all_recovery_waiters(rh->context);
 639 }
 640 EXPORT_SYMBOL_GPL(dm_rh_recovery_prepare);
 641
 642 /*
 643  * Returns any quiesced regions.
 644  */
 645 struct dm_region *dm_rh_recovery_start(struct dm_region_hash *rh)
 646 {
 647         struct dm_region *reg = NULL;
 648
 649         spin_lock_irq(&rh->region_lock);
 650         if (!list_empty(&rh->quiesced_regions)) {
 651                 reg = list_entry(rh->quiesced_regions.next,
 652                                  struct dm_region, list);
 653                 list_del_init(&reg->list);  /* remove from the quiesced list */
 654         }
 655         spin_unlock_irq(&rh->region_lock);
 656
 657         return reg;
 658 }
 659 EXPORT_SYMBOL_GPL(dm_rh_recovery_start);
 660
 661 void dm_rh_recovery_end(struct dm_region *reg, int success)
 662 {
 663         struct dm_region_hash *rh = reg->rh;
 664
 665         spin_lock_irq(&rh->region_lock);
 666         if (success)
 667                 list_add(&reg->list, &reg->rh->recovered_regions);
 668         else
 669                 list_add(&reg->list, &reg->rh->failed_recovered_regions);
 670
 671         spin_unlock_irq(&rh->region_lock);
 672
 673         rh->wakeup_workers(rh->context);
 674 }
 675 EXPORT_SYMBOL_GPL(dm_rh_recovery_end);
 676
 677 /* Return recovery in flight count. */
 678 int dm_rh_recovery_in_flight(struct dm_region_hash *rh)
 679 {
 680         return atomic_read(&rh->recovery_in_flight);
 681 }
 682 EXPORT_SYMBOL_GPL(dm_rh_recovery_in_flight);
 683
 684 int dm_rh_flush(struct dm_region_hash *rh)
 685 {
 686         return rh->log->type->flush(rh->log);
 687 }
 688 EXPORT_SYMBOL_GPL(dm_rh_flush);
 689
 690 void dm_rh_delay(struct dm_region_hash *rh, struct bio *bio)
 691 {
 692         struct dm_region *reg;
 693
 694         read_lock(&rh->hash_lock);
 695         reg = __rh_find(rh, dm_rh_bio_to_region(rh, bio));
 696         bio_list_add(&reg->delayed_bios, bio);
 697         read_unlock(&rh->hash_lock);
 698 }
 699 EXPORT_SYMBOL_GPL(dm_rh_delay);
 700
 701 void dm_rh_stop_recovery(struct dm_region_hash *rh)
 702 {
 703         int i;
 704
 705         /* wait for any recovering regions */
 706         for (i = 0; i < rh->max_recovery; i++)
 707                 down(&rh->recovery_count);
 708 }
 709 EXPORT_SYMBOL_GPL(dm_rh_stop_recovery);
 710
 711 void dm_rh_start_recovery(struct dm_region_hash *rh)
 712 {
 713         int i;
 714
 715         for (i = 0; i < rh->max_recovery; i++)
 716                 up(&rh->recovery_count);
 717
 718         rh->wakeup_workers(rh->context);
 719 }
 720 EXPORT_SYMBOL_GPL(dm_rh_start_recovery);
 721
 722 MODULE_DESCRIPTION(DM_NAME " region hash");
 723 MODULE_AUTHOR("Joe Thornber/Heinz Mauelshagen <dm-devel@redhat.com>");
 724 MODULE_LICENSE("GPL");