SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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/vmalloc.h>
  15
  16 #include "dm.h"
  17
  18 #define DM_MSG_PREFIX   "region hash"
  19
  20 /*-----------------------------------------------------------------
  21  * Region hash
  22  *
  23  * The mirror splits itself up into discrete regions.  Each
  24  * region can be in one of three states: clean, dirty,
  25  * nosync.  There is no need to put clean regions in the hash.
  26  *
  27  * In addition to being present in the hash table a region _may_
  28  * be present on one of three lists.
  29  *
  30  *   clean_regions: Regions on this list have no io pending to
  31  *   them, they are in sync, we are no longer interested in them,
  32  *   they are dull.  dm_rh_update_states() will remove them from the
  33  *   hash table.
  34  *
  35  *   quiesced_regions: These regions have been spun down, ready
  36  *   for recovery.  rh_recovery_start() will remove regions from
  37  *   this list and hand them to kmirrord, which will schedule the
  38  *   recovery io with kcopyd.
  39  *
  40  *   recovered_regions: Regions that kcopyd has successfully
  41  *   recovered.  dm_rh_update_states() will now schedule any delayed
  42  *   io, up the recovery_count, and remove the region from the
  43  *   hash.
  44  *
  45  * There are 2 locks:
  46  *   A rw spin lock 'hash_lock' protects just the hash table,
  47  *   this is never held in write mode from interrupt context,
  48  *   which I believe means that we only have to disable irqs when
  49  *   doing a write lock.
  50  *
  51  *   An ordinary spin lock 'region_lock' that protects the three
  52  *   lists in the region_hash, with the 'state', 'list' and
  53  *   'delayed_bios' fields of the regions.  This is used from irq
  54  *   context, so all other uses will have to suspend local irqs.
  55  *---------------------------------------------------------------*/
  56 struct dm_region_hash {
  57         uint32_t region_size;
  58         unsigned region_shift;
  59
  60         /* holds persistent region state */
  61         struct dm_dirty_log *log;
  62
  63         /* hash table */
  64         rwlock_t hash_lock;
  65         mempool_t *region_pool;
  66         unsigned mask;
  67         unsigned nr_buckets;
  68         unsigned prime;
  69         unsigned shift;
  70         struct list_head *buckets;
  71
  72         unsigned max_recovery; /* Max # of regions to recover in parallel */
  73
  74         spinlock_t region_lock;
  75         atomic_t recovery_in_flight;
  76         struct semaphore recovery_count;
  77         struct list_head clean_regions;
  78         struct list_head quiesced_regions;
  79         struct list_head recovered_regions;
  80         struct list_head failed_recovered_regions;
  81
  82         /*
  83          * If there was a barrier failure no regions can be marked clean.
  84          */
  85         int barrier_failure;
  86
  87         void *context;
  88         sector_t target_begin;
  89
  90         /* Callback function to schedule bios writes */
  91         void (*dispatch_bios)(void *context, struct bio_list *bios);
  92
  93         /* Callback function to wakeup callers worker thread. */
  94         void (*wakeup_workers)(void *context);
  95
  96         /* Callback function to wakeup callers recovery waiters. */
  97         void (*wakeup_all_recovery_waiters)(void *context);
  98 };
  99
 100 struct dm_region {
 101         struct dm_region_hash *rh;      /* FIXME: can we get rid of this ? */
 102         region_t key;
 103         int state;
 104
 105         struct list_head hash_list;
 106         struct list_head list;
 107
 108         atomic_t pending;
 109         struct bio_list delayed_bios;
 110 };
 111
 112 /*
 113  * Conversion fns
 114  */
 115 static region_t dm_rh_sector_to_region(struct dm_region_hash *rh, sector_t sector)
 116 {
 117         return sector >> rh->region_shift;
 118 }
 119
 120 sector_t dm_rh_region_to_sector(struct dm_region_hash *rh, region_t region)
 121 {
 122         return region << rh->region_shift;
 123 }
 124 EXPORT_SYMBOL_GPL(dm_rh_region_to_sector);
 125
 126 region_t dm_rh_bio_to_region(struct dm_region_hash *rh, struct bio *bio)
 127 {
 128         return dm_rh_sector_to_region(rh, bio->bi_sector - rh->target_begin);
 129 }
 130 EXPORT_SYMBOL_GPL(dm_rh_bio_to_region);
 131
 132 void *dm_rh_region_context(struct dm_region *reg)
 133 {
 134         return reg->rh->context;
 135 }
 136 EXPORT_SYMBOL_GPL(dm_rh_region_context);
 137
 138 region_t dm_rh_get_region_key(struct dm_region *reg)
 139 {
 140         return reg->key;
 141 }
 142 EXPORT_SYMBOL_GPL(dm_rh_get_region_key);
 143
 144 sector_t dm_rh_get_region_size(struct dm_region_hash *rh)
 145 {
 146         return rh->region_size;
 147 }
 148 EXPORT_SYMBOL_GPL(dm_rh_get_region_size);
 149
 150 /*
 151  * FIXME: shall we pass in a structure instead of all these args to
 152  * dm_region_hash_create()????
 153  */
 154 #define RH_HASH_MULT 2654435387U
 155 #define RH_HASH_SHIFT 12
 156
 157 #define MIN_REGIONS 64
 158 struct dm_region_hash *dm_region_hash_create(
 159                 void *context, void (*dispatch_bios)(void *context,
 160                                                      struct bio_list *bios),
 161                 void (*wakeup_workers)(void *context),
 162                 void (*wakeup_all_recovery_waiters)(void *context),
 163                 sector_t target_begin, unsigned max_recovery,
 164                 struct dm_dirty_log *log, uint32_t region_size,
 165                 region_t nr_regions)
 166 {
 167         struct dm_region_hash *rh;
 168         unsigned nr_buckets, max_buckets;
 169         size_t i;
 170
 171         /*
 172          * Calculate a suitable number of buckets for our hash
 173          * table.
 174          */
 175         max_buckets = nr_regions >> 6;
 176         for (nr_buckets = 128u; nr_buckets < max_buckets; nr_buckets <<= 1)
 177                 ;
 178         nr_buckets >>= 1;
 179
 180         rh = kmalloc(sizeof(*rh), GFP_KERNEL);
 181         if (!rh) {
 182                 DMERR("unable to allocate region hash memory");
 183                 return ERR_PTR(-ENOMEM);
 184         }
 185
 186         rh->context = context;
 187         rh->dispatch_bios = dispatch_bios;
 188         rh->wakeup_workers = wakeup_workers;
 189         rh->wakeup_all_recovery_waiters = wakeup_all_recovery_waiters;
 190         rh->target_begin = target_begin;
 191         rh->max_recovery = max_recovery;
 192         rh->log = log;
 193         rh->region_size = region_size;
 194         rh->region_shift = ffs(region_size) - 1;
 195         rwlock_init(&rh->hash_lock);
 196         rh->mask = nr_buckets - 1;
 197         rh->nr_buckets = nr_buckets;
 198
 199         rh->shift = RH_HASH_SHIFT;
 200         rh->prime = RH_HASH_MULT;
 201
 202         rh->buckets = vmalloc(nr_buckets * sizeof(*rh->buckets));
 203         if (!rh->buckets) {
 204                 DMERR("unable to allocate region hash bucket memory");
 205                 kfree(rh);
 206                 return ERR_PTR(-ENOMEM);
 207         }
 208
 209         for (i = 0; i < nr_buckets; i++)
 210                 INIT_LIST_HEAD(rh->buckets + i);
 211
 212         spin_lock_init(&rh->region_lock);
 213         sema_init(&rh->recovery_count, 0);
 214         atomic_set(&rh->recovery_in_flight, 0);
 215         INIT_LIST_HEAD(&rh->clean_regions);
 216         INIT_LIST_HEAD(&rh->quiesced_regions);
 217         INIT_LIST_HEAD(&rh->recovered_regions);
 218         INIT_LIST_HEAD(&rh->failed_recovered_regions);
 219         rh->barrier_failure = 0;
 220
 221         rh->region_pool = mempool_create_kmalloc_pool(MIN_REGIONS,
 222                                                       sizeof(struct dm_region));
 223         if (!rh->region_pool) {
 224                 vfree(rh->buckets);
 225                 kfree(rh);
 226                 rh = ERR_PTR(-ENOMEM);
 227         }
 228
 229         return rh;
 230 }
 231 EXPORT_SYMBOL_GPL(dm_region_hash_create);
 232
 233 void dm_region_hash_destroy(struct dm_region_hash *rh)
 234 {
 235         unsigned h;
 236         struct dm_region *reg, *nreg;
 237
 238         BUG_ON(!list_empty(&rh->quiesced_regions));
 239         for (h = 0; h < rh->nr_buckets; h++) {
 240                 list_for_each_entry_safe(reg, nreg, rh->buckets + h,
 241                                          hash_list) {
 242                         BUG_ON(atomic_read(&reg->pending));
 243                         mempool_free(reg, rh->region_pool);
 244                 }
 245         }
 246
 247         if (rh->log)
 248                 dm_dirty_log_destroy(rh->log);
 249
 250         if (rh->region_pool)
 251                 mempool_destroy(rh->region_pool);
 252
 253         vfree(rh->buckets);
 254         kfree(rh);
 255 }
 256 EXPORT_SYMBOL_GPL(dm_region_hash_destroy);
 257
 258 struct dm_dirty_log *dm_rh_dirty_log(struct dm_region_hash *rh)
 259 {
 260         return rh->log;
 261 }
 262 EXPORT_SYMBOL_GPL(dm_rh_dirty_log);
 263
 264 static unsigned rh_hash(struct dm_region_hash *rh, region_t region)
 265 {
 266         return (unsigned) ((region * rh->prime) >> rh->shift) & rh->mask;
 267 }
 268
 269 static struct dm_region *__rh_lookup(struct dm_region_hash *rh, region_t region)
 270 {
 271         struct dm_region *reg;
 272         struct list_head *bucket = rh->buckets + rh_hash(rh, region);
 273
 274         list_for_each_entry(reg, bucket, hash_list)
 275                 if (reg->key == region)
 276                         return reg;
 277
 278         return NULL;
 279 }
 280
 281 static void __rh_insert(struct dm_region_hash *rh, struct dm_region *reg)
 282 {
 283         list_add(&reg->hash_list, rh->buckets + rh_hash(rh, reg->key));
 284 }
 285
 286 static struct dm_region *__rh_alloc(struct dm_region_hash *rh, region_t region)
 287 {
 288         struct dm_region *reg, *nreg;
 289
 290         nreg = mempool_alloc(rh->region_pool, GFP_ATOMIC);
 291         if (unlikely(!nreg))
 292                 nreg = kmalloc(sizeof(*nreg), GFP_NOIO | __GFP_NOFAIL);
 293
 294         nreg->state = rh->log->type->in_sync(rh->log, region, 1) ?
 295                       DM_RH_CLEAN : DM_RH_NOSYNC;
 296         nreg->rh = rh;
 297         nreg->key = region;
 298         INIT_LIST_HEAD(&nreg->list);
 299         atomic_set(&nreg->pending, 0);
 300         bio_list_init(&nreg->delayed_bios);
 301
 302         write_lock_irq(&rh->hash_lock);
 303         reg = __rh_lookup(rh, region);
 304         if (reg)
 305                 /* We lost the race. */
 306                 mempool_free(nreg, rh->region_pool);
 307         else {
 308                 __rh_insert(rh, nreg);
 309                 if (nreg->state == DM_RH_CLEAN) {
 310                         spin_lock(&rh->region_lock);
 311                         list_add(&nreg->list, &rh->clean_regions);
 312                         spin_unlock(&rh->region_lock);
 313                 }
 314
 315                 reg = nreg;
 316         }
 317         write_unlock_irq(&rh->hash_lock);
 318
 319         return reg;
 320 }
 321
 322 static struct dm_region *__rh_find(struct dm_region_hash *rh, region_t region)
 323 {
 324         struct dm_region *reg;
 325
 326         reg = __rh_lookup(rh, region);
 327         if (!reg) {
 328                 read_unlock(&rh->hash_lock);
 329                 reg = __rh_alloc(rh, region);
 330                 read_lock(&rh->hash_lock);
 331         }
 332
 333         return reg;
 334 }
 335
 336 int dm_rh_get_state(struct dm_region_hash *rh, region_t region, int may_block)
 337 {
 338         int r;
 339         struct dm_region *reg;
 340
 341         read_lock(&rh->hash_lock);
 342         reg = __rh_lookup(rh, region);
 343         read_unlock(&rh->hash_lock);
 344
 345         if (reg)
 346                 return reg->state;
 347
 348         /*
 349          * The region wasn't in the hash, so we fall back to the
 350          * dirty log.
 351          */
 352         r = rh->log->type->in_sync(rh->log, region, may_block);
 353
 354         /*
 355          * Any error from the dirty log (eg. -EWOULDBLOCK) gets
 356          * taken as a DM_RH_NOSYNC
 357          */
 358         return r == 1 ? DM_RH_CLEAN : DM_RH_NOSYNC;
 359 }
 360 EXPORT_SYMBOL_GPL(dm_rh_get_state);
 361
 362 static void complete_resync_work(struct dm_region *reg, int success)
 363 {
 364         struct dm_region_hash *rh = reg->rh;
 365
 366         rh->log->type->set_region_sync(rh->log, reg->key, success);
 367
 368         /*
 369          * Dispatch the bios before we call 'wake_up_all'.
 370          * This is important because if we are suspending,
 371          * we want to know that recovery is complete and
 372          * the work queue is flushed.  If we wake_up_all
 373          * before we dispatch_bios (queue bios and call wake()),
 374          * then we risk suspending before the work queue
 375          * has been properly flushed.
 376          */
 377         rh->dispatch_bios(rh->context, &reg->delayed_bios);
 378         if (atomic_dec_and_test(&rh->recovery_in_flight))
 379                 rh->wakeup_all_recovery_waiters(rh->context);
 380         up(&rh->recovery_count);
 381 }
 382
 383 /* dm_rh_mark_nosync
 384  * @ms
 385  * @bio
 386  * @done
 387  * @error
 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,
 396                        struct bio *bio, unsigned done, int error)
 397 {
 398         unsigned long flags;
 399         struct dm_dirty_log *log = rh->log;
 400         struct dm_region *reg;
 401         region_t region = dm_rh_bio_to_region(rh, bio);
 402         int recovering = 0;
 403
 404         if (bio_empty_barrier(bio)) {
 405                 rh->barrier_failure = 1;
 406                 return;
 407         }
 408
 409         /* We must inform the log that the sync count has changed. */
 410         log->type->set_region_sync(log, region, 0);
 411
 412         read_lock(&rh->hash_lock);
 413         reg = __rh_find(rh, region);
 414         read_unlock(&rh->hash_lock);
 415
 416         /* region hash entry should exist because write was in-flight */
 417         BUG_ON(!reg);
 418         BUG_ON(!list_empty(&reg->list));
 419
 420         spin_lock_irqsave(&rh->region_lock, flags);
 421         /*
 422          * Possible cases:
 423          *   1) DM_RH_DIRTY
 424          *   2) DM_RH_NOSYNC: was dirty, other preceeding writes failed
 425          *   3) DM_RH_RECOVERING: flushing pending writes
 426          * Either case, the region should have not been connected to list.
 427          */
 428         recovering = (reg->state == DM_RH_RECOVERING);
 429         reg->state = DM_RH_NOSYNC;
 430         BUG_ON(!list_empty(&reg->list));
 431         spin_unlock_irqrestore(&rh->region_lock, flags);
 432
 433         bio_endio(bio, error);
 434         if (recovering)
 435                 complete_resync_work(reg, 0);
 436 }
 437 EXPORT_SYMBOL_GPL(dm_rh_mark_nosync);
 438
 439 void dm_rh_update_states(struct dm_region_hash *rh, int errors_handled)
 440 {
 441         struct dm_region *reg, *next;
 442
 443         LIST_HEAD(clean);
 444         LIST_HEAD(recovered);
 445         LIST_HEAD(failed_recovered);
 446
 447         /*
 448          * Quickly grab the lists.
 449          */
 450         write_lock_irq(&rh->hash_lock);
 451         spin_lock(&rh->region_lock);
 452         if (!list_empty(&rh->clean_regions)) {
 453                 list_splice_init(&rh->clean_regions, &clean);
 454
 455                 list_for_each_entry(reg, &clean, list)
 456                         list_del(&reg->hash_list);
 457         }
 458
 459         if (!list_empty(&rh->recovered_regions)) {
 460                 list_splice_init(&rh->recovered_regions, &recovered);
 461
 462                 list_for_each_entry(reg, &recovered, list)
 463                         list_del(&reg->hash_list);
 464         }
 465
 466         if (!list_empty(&rh->failed_recovered_regions)) {
 467                 list_splice_init(&rh->failed_recovered_regions,
 468                                  &failed_recovered);
 469
 470                 list_for_each_entry(reg, &failed_recovered, list)
 471                         list_del(&reg->hash_list);
 472         }
 473
 474         spin_unlock(&rh->region_lock);
 475         write_unlock_irq(&rh->hash_lock);
 476
 477         /*
 478          * All the regions on the recovered and clean lists have
 479          * now been pulled out of the system, so no need to do
 480          * any more locking.
 481          */
 482         list_for_each_entry_safe(reg, next, &recovered, list) {
 483                 rh->log->type->clear_region(rh->log, reg->key);
 484                 complete_resync_work(reg, 1);
 485                 mempool_free(reg, rh->region_pool);
 486         }
 487
 488         list_for_each_entry_safe(reg, next, &failed_recovered, list) {
 489                 complete_resync_work(reg, errors_handled ? 0 : 1);
 490                 mempool_free(reg, rh->region_pool);
 491         }
 492
 493         list_for_each_entry_safe(reg, next, &clean, list) {
 494                 rh->log->type->clear_region(rh->log, reg->key);
 495                 mempool_free(reg, rh->region_pool);
 496         }
 497
 498         rh->log->type->flush(rh->log);
 499 }
 500 EXPORT_SYMBOL_GPL(dm_rh_update_states);
 501
 502 static void rh_inc(struct dm_region_hash *rh, region_t region)
 503 {
 504         struct dm_region *reg;
 505
 506         read_lock(&rh->hash_lock);
 507         reg = __rh_find(rh, region);
 508
 509         spin_lock_irq(&rh->region_lock);
 510         atomic_inc(&reg->pending);
 511
 512         if (reg->state == DM_RH_CLEAN) {
 513                 reg->state = DM_RH_DIRTY;
 514                 list_del_init(&reg->list);      /* take off the clean list */
 515                 spin_unlock_irq(&rh->region_lock);
 516
 517                 rh->log->type->mark_region(rh->log, reg->key);
 518         } else
 519                 spin_unlock_irq(&rh->region_lock);
 520
 521
 522         read_unlock(&rh->hash_lock);
 523 }
 524
 525 void dm_rh_inc_pending(struct dm_region_hash *rh, struct bio_list *bios)
 526 {
 527         struct bio *bio;
 528
 529         for (bio = bios->head; bio; bio = bio->bi_next) {
 530                 if (bio_empty_barrier(bio))
 531                         continue;
 532                 rh_inc(rh, dm_rh_bio_to_region(rh, bio));
 533         }
 534 }
 535 EXPORT_SYMBOL_GPL(dm_rh_inc_pending);
 536
 537 void dm_rh_dec(struct dm_region_hash *rh, region_t region)
 538 {
 539         unsigned long flags;
 540         struct dm_region *reg;
 541         int should_wake = 0;
 542
 543         read_lock(&rh->hash_lock);
 544         reg = __rh_lookup(rh, region);
 545         read_unlock(&rh->hash_lock);
 546
 547         spin_lock_irqsave(&rh->region_lock, flags);
 548         if (atomic_dec_and_test(&reg->pending)) {
 549                 /*
 550                  * There is no pending I/O for this region.
 551                  * We can move the region to corresponding list for next action.
 552                  * At this point, the region is not yet connected to any list.
 553                  *
 554                  * If the state is DM_RH_NOSYNC, the region should be kept off
 555                  * from clean list.
 556                  * The hash entry for DM_RH_NOSYNC will remain in memory
 557                  * until the region is recovered or the map is reloaded.
 558                  */
 559
 560                 /* do nothing for DM_RH_NOSYNC */
 561                 if (unlikely(rh->barrier_failure)) {
 562                         /*
 563                          * If a write barrier failed some time ago, we
 564                          * don't know whether or not this write made it
 565                          * to the disk, so we must resync the device.
 566                          */
 567                         reg->state = DM_RH_NOSYNC;
 568                 } else if (reg->state == DM_RH_RECOVERING) {
 569                         list_add_tail(&reg->list, &rh->quiesced_regions);
 570                 } else if (reg->state == DM_RH_DIRTY) {
 571                         reg->state = DM_RH_CLEAN;
 572                         list_add(&reg->list, &rh->clean_regions);
 573                 }
 574                 should_wake = 1;
 575         }
 576         spin_unlock_irqrestore(&rh->region_lock, flags);
 577
 578         if (should_wake)
 579                 rh->wakeup_workers(rh->context);
 580 }
 581 EXPORT_SYMBOL_GPL(dm_rh_dec);
 582
 583 /*
 584  * Starts quiescing a region in preparation for recovery.
 585  */
 586 static int __rh_recovery_prepare(struct dm_region_hash *rh)
 587 {
 588         int r;
 589         region_t region;
 590         struct dm_region *reg;
 591
 592         /*
 593          * Ask the dirty log what's next.
 594          */
 595         r = rh->log->type->get_resync_work(rh->log, &region);
 596         if (r <= 0)
 597                 return r;
 598
 599         /*
 600          * Get this region, and start it quiescing by setting the
 601          * recovering flag.
 602          */
 603         read_lock(&rh->hash_lock);
 604         reg = __rh_find(rh, region);
 605         read_unlock(&rh->hash_lock);
 606
 607         spin_lock_irq(&rh->region_lock);
 608         reg->state = DM_RH_RECOVERING;
 609
 610         /* Already quiesced ? */
 611         if (atomic_read(&reg->pending))
 612                 list_del_init(&reg->list);
 613         else
 614                 list_move(&reg->list, &rh->quiesced_regions);
 615
 616         spin_unlock_irq(&rh->region_lock);
 617
 618         return 1;
 619 }
 620
 621 void dm_rh_recovery_prepare(struct dm_region_hash *rh)
 622 {
 623         /* Extra reference to avoid race with dm_rh_stop_recovery */
 624         atomic_inc(&rh->recovery_in_flight);
 625
 626         while (!down_trylock(&rh->recovery_count)) {
 627                 atomic_inc(&rh->recovery_in_flight);
 628                 if (__rh_recovery_prepare(rh) <= 0) {
 629                         atomic_dec(&rh->recovery_in_flight);
 630                         up(&rh->recovery_count);
 631                         break;
 632                 }
 633         }
 634
 635         /* Drop the extra reference */
 636         if (atomic_dec_and_test(&rh->recovery_in_flight))
 637                 rh->wakeup_all_recovery_waiters(rh->context);
 638 }
 639 EXPORT_SYMBOL_GPL(dm_rh_recovery_prepare);
 640
 641 /*
 642  * Returns any quiesced regions.
 643  */
 644 struct dm_region *dm_rh_recovery_start(struct dm_region_hash *rh)
 645 {
 646         struct dm_region *reg = NULL;
 647
 648         spin_lock_irq(&rh->region_lock);
 649         if (!list_empty(&rh->quiesced_regions)) {
 650                 reg = list_entry(rh->quiesced_regions.next,
 651                                  struct dm_region, list);
 652                 list_del_init(&reg->list);  /* remove from the quiesced list */
 653         }
 654         spin_unlock_irq(&rh->region_lock);
 655
 656         return reg;
 657 }
 658 EXPORT_SYMBOL_GPL(dm_rh_recovery_start);
 659
 660 void dm_rh_recovery_end(struct dm_region *reg, int success)
 661 {
 662         struct dm_region_hash *rh = reg->rh;
 663
 664         spin_lock_irq(&rh->region_lock);
 665         if (success)
 666                 list_add(&reg->list, &reg->rh->recovered_regions);
 667         else {
 668                 reg->state = DM_RH_NOSYNC;
 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");