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  *
 387  * The bio was written on some mirror(s) but failed on other mirror(s).
 388  * We can successfully endio the bio but should avoid the region being
 389  * marked clean by setting the state DM_RH_NOSYNC.
 390  *
 391  * This function is _not_ safe in interrupt context!
 392  */
 393 void dm_rh_mark_nosync(struct dm_region_hash *rh, struct bio *bio)
 394 {
 395         unsigned long flags;
 396         struct dm_dirty_log *log = rh->log;
 397         struct dm_region *reg;
 398         region_t region = dm_rh_bio_to_region(rh, bio);
 399         int recovering = 0;
 400
 401         if (bio_empty_barrier(bio)) {
 402                 rh->barrier_failure = 1;
 403                 return;
 404         }
 405
 406         /* We must inform the log that the sync count has changed. */
 407         log->type->set_region_sync(log, region, 0);
 408
 409         read_lock(&rh->hash_lock);
 410         reg = __rh_find(rh, region);
 411         read_unlock(&rh->hash_lock);
 412
 413         /* region hash entry should exist because write was in-flight */
 414         BUG_ON(!reg);
 415         BUG_ON(!list_empty(&reg->list));
 416
 417         spin_lock_irqsave(&rh->region_lock, flags);
 418         /*
 419          * Possible cases:
 420          *   1) DM_RH_DIRTY
 421          *   2) DM_RH_NOSYNC: was dirty, other preceeding writes failed
 422          *   3) DM_RH_RECOVERING: flushing pending writes
 423          * Either case, the region should have not been connected to list.
 424          */
 425         recovering = (reg->state == DM_RH_RECOVERING);
 426         reg->state = DM_RH_NOSYNC;
 427         BUG_ON(!list_empty(&reg->list));
 428         spin_unlock_irqrestore(&rh->region_lock, flags);
 429
 430         if (recovering)
 431                 complete_resync_work(reg, 0);
 432 }
 433 EXPORT_SYMBOL_GPL(dm_rh_mark_nosync);
 434
 435 void dm_rh_update_states(struct dm_region_hash *rh, int errors_handled)
 436 {
 437         struct dm_region *reg, *next;
 438
 439         LIST_HEAD(clean);
 440         LIST_HEAD(recovered);
 441         LIST_HEAD(failed_recovered);
 442
 443         /*
 444          * Quickly grab the lists.
 445          */
 446         write_lock_irq(&rh->hash_lock);
 447         spin_lock(&rh->region_lock);
 448         if (!list_empty(&rh->clean_regions)) {
 449                 list_splice_init(&rh->clean_regions, &clean);
 450
 451                 list_for_each_entry(reg, &clean, list)
 452                         list_del(&reg->hash_list);
 453         }
 454
 455         if (!list_empty(&rh->recovered_regions)) {
 456                 list_splice_init(&rh->recovered_regions, &recovered);
 457
 458                 list_for_each_entry(reg, &recovered, list)
 459                         list_del(&reg->hash_list);
 460         }
 461
 462         if (!list_empty(&rh->failed_recovered_regions)) {
 463                 list_splice_init(&rh->failed_recovered_regions,
 464                                  &failed_recovered);
 465
 466                 list_for_each_entry(reg, &failed_recovered, list)
 467                         list_del(&reg->hash_list);
 468         }
 469
 470         spin_unlock(&rh->region_lock);
 471         write_unlock_irq(&rh->hash_lock);
 472
 473         /*
 474          * All the regions on the recovered and clean lists have
 475          * now been pulled out of the system, so no need to do
 476          * any more locking.
 477          */
 478         list_for_each_entry_safe(reg, next, &recovered, list) {
 479                 rh->log->type->clear_region(rh->log, reg->key);
 480                 complete_resync_work(reg, 1);
 481                 mempool_free(reg, rh->region_pool);
 482         }
 483
 484         list_for_each_entry_safe(reg, next, &failed_recovered, list) {
 485                 complete_resync_work(reg, errors_handled ? 0 : 1);
 486                 mempool_free(reg, rh->region_pool);
 487         }
 488
 489         list_for_each_entry_safe(reg, next, &clean, list) {
 490                 rh->log->type->clear_region(rh->log, reg->key);
 491                 mempool_free(reg, rh->region_pool);
 492         }
 493
 494         rh->log->type->flush(rh->log);
 495 }
 496 EXPORT_SYMBOL_GPL(dm_rh_update_states);
 497
 498 static void rh_inc(struct dm_region_hash *rh, region_t region)
 499 {
 500         struct dm_region *reg;
 501
 502         read_lock(&rh->hash_lock);
 503         reg = __rh_find(rh, region);
 504
 505         spin_lock_irq(&rh->region_lock);
 506         atomic_inc(&reg->pending);
 507
 508         if (reg->state == DM_RH_CLEAN) {
 509                 reg->state = DM_RH_DIRTY;
 510                 list_del_init(&reg->list);      /* take off the clean list */
 511                 spin_unlock_irq(&rh->region_lock);
 512
 513                 rh->log->type->mark_region(rh->log, reg->key);
 514         } else
 515                 spin_unlock_irq(&rh->region_lock);
 516
 517
 518         read_unlock(&rh->hash_lock);
 519 }
 520
 521 void dm_rh_inc_pending(struct dm_region_hash *rh, struct bio_list *bios)
 522 {
 523         struct bio *bio;
 524
 525         for (bio = bios->head; bio; bio = bio->bi_next) {
 526                 if (bio_empty_barrier(bio))
 527                         continue;
 528                 rh_inc(rh, dm_rh_bio_to_region(rh, bio));
 529         }
 530 }
 531 EXPORT_SYMBOL_GPL(dm_rh_inc_pending);
 532
 533 void dm_rh_dec(struct dm_region_hash *rh, region_t region)
 534 {
 535         unsigned long flags;
 536         struct dm_region *reg;
 537         int should_wake = 0;
 538
 539         read_lock(&rh->hash_lock);
 540         reg = __rh_lookup(rh, region);
 541         read_unlock(&rh->hash_lock);
 542
 543         spin_lock_irqsave(&rh->region_lock, flags);
 544         if (atomic_dec_and_test(&reg->pending)) {
 545                 /*
 546                  * There is no pending I/O for this region.
 547                  * We can move the region to corresponding list for next action.
 548                  * At this point, the region is not yet connected to any list.
 549                  *
 550                  * If the state is DM_RH_NOSYNC, the region should be kept off
 551                  * from clean list.
 552                  * The hash entry for DM_RH_NOSYNC will remain in memory
 553                  * until the region is recovered or the map is reloaded.
 554                  */
 555
 556                 /* do nothing for DM_RH_NOSYNC */
 557                 if (unlikely(rh->barrier_failure)) {
 558                         /*
 559                          * If a write barrier failed some time ago, we
 560                          * don't know whether or not this write made it
 561                          * to the disk, so we must resync the device.
 562                          */
 563                         reg->state = DM_RH_NOSYNC;
 564                 } else if (reg->state == DM_RH_RECOVERING) {
 565                         list_add_tail(&reg->list, &rh->quiesced_regions);
 566                 } else if (reg->state == DM_RH_DIRTY) {
 567                         reg->state = DM_RH_CLEAN;
 568                         list_add(&reg->list, &rh->clean_regions);
 569                 }
 570                 should_wake = 1;
 571         }
 572         spin_unlock_irqrestore(&rh->region_lock, flags);
 573
 574         if (should_wake)
 575                 rh->wakeup_workers(rh->context);
 576 }
 577 EXPORT_SYMBOL_GPL(dm_rh_dec);
 578
 579 /*
 580  * Starts quiescing a region in preparation for recovery.
 581  */
 582 static int __rh_recovery_prepare(struct dm_region_hash *rh)
 583 {
 584         int r;
 585         region_t region;
 586         struct dm_region *reg;
 587
 588         /*
 589          * Ask the dirty log what's next.
 590          */
 591         r = rh->log->type->get_resync_work(rh->log, &region);
 592         if (r <= 0)
 593                 return r;
 594
 595         /*
 596          * Get this region, and start it quiescing by setting the
 597          * recovering flag.
 598          */
 599         read_lock(&rh->hash_lock);
 600         reg = __rh_find(rh, region);
 601         read_unlock(&rh->hash_lock);
 602
 603         spin_lock_irq(&rh->region_lock);
 604         reg->state = DM_RH_RECOVERING;
 605
 606         /* Already quiesced ? */
 607         if (atomic_read(&reg->pending))
 608                 list_del_init(&reg->list);
 609         else
 610                 list_move(&reg->list, &rh->quiesced_regions);
 611
 612         spin_unlock_irq(&rh->region_lock);
 613
 614         return 1;
 615 }
 616
 617 void dm_rh_recovery_prepare(struct dm_region_hash *rh)
 618 {
 619         /* Extra reference to avoid race with dm_rh_stop_recovery */
 620         atomic_inc(&rh->recovery_in_flight);
 621
 622         while (!down_trylock(&rh->recovery_count)) {
 623                 atomic_inc(&rh->recovery_in_flight);
 624                 if (__rh_recovery_prepare(rh) <= 0) {
 625                         atomic_dec(&rh->recovery_in_flight);
 626                         up(&rh->recovery_count);
 627                         break;
 628                 }
 629         }
 630
 631         /* Drop the extra reference */
 632         if (atomic_dec_and_test(&rh->recovery_in_flight))
 633                 rh->wakeup_all_recovery_waiters(rh->context);
 634 }
 635 EXPORT_SYMBOL_GPL(dm_rh_recovery_prepare);
 636
 637 /*
 638  * Returns any quiesced regions.
 639  */
 640 struct dm_region *dm_rh_recovery_start(struct dm_region_hash *rh)
 641 {
 642         struct dm_region *reg = NULL;
 643
 644         spin_lock_irq(&rh->region_lock);
 645         if (!list_empty(&rh->quiesced_regions)) {
 646                 reg = list_entry(rh->quiesced_regions.next,
 647                                  struct dm_region, list);
 648                 list_del_init(&reg->list);  /* remove from the quiesced list */
 649         }
 650         spin_unlock_irq(&rh->region_lock);
 651
 652         return reg;
 653 }
 654 EXPORT_SYMBOL_GPL(dm_rh_recovery_start);
 655
 656 void dm_rh_recovery_end(struct dm_region *reg, int success)
 657 {
 658         struct dm_region_hash *rh = reg->rh;
 659
 660         spin_lock_irq(&rh->region_lock);
 661         if (success)
 662                 list_add(&reg->list, &reg->rh->recovered_regions);
 663         else
 664                 list_add(&reg->list, &reg->rh->failed_recovered_regions);
 665
 666         spin_unlock_irq(&rh->region_lock);
 667
 668         rh->wakeup_workers(rh->context);
 669 }
 670 EXPORT_SYMBOL_GPL(dm_rh_recovery_end);
 671
 672 /* Return recovery in flight count. */
 673 int dm_rh_recovery_in_flight(struct dm_region_hash *rh)
 674 {
 675         return atomic_read(&rh->recovery_in_flight);
 676 }
 677 EXPORT_SYMBOL_GPL(dm_rh_recovery_in_flight);
 678
 679 int dm_rh_flush(struct dm_region_hash *rh)
 680 {
 681         return rh->log->type->flush(rh->log);
 682 }
 683 EXPORT_SYMBOL_GPL(dm_rh_flush);
 684
 685 void dm_rh_delay(struct dm_region_hash *rh, struct bio *bio)
 686 {
 687         struct dm_region *reg;
 688
 689         read_lock(&rh->hash_lock);
 690         reg = __rh_find(rh, dm_rh_bio_to_region(rh, bio));
 691         bio_list_add(&reg->delayed_bios, bio);
 692         read_unlock(&rh->hash_lock);
 693 }
 694 EXPORT_SYMBOL_GPL(dm_rh_delay);
 695
 696 void dm_rh_stop_recovery(struct dm_region_hash *rh)
 697 {
 698         int i;
 699
 700         /* wait for any recovering regions */
 701         for (i = 0; i < rh->max_recovery; i++)
 702                 down(&rh->recovery_count);
 703 }
 704 EXPORT_SYMBOL_GPL(dm_rh_stop_recovery);
 705
 706 void dm_rh_start_recovery(struct dm_region_hash *rh)
 707 {
 708         int i;
 709
 710         for (i = 0; i < rh->max_recovery; i++)
 711                 up(&rh->recovery_count);
 712
 713         rh->wakeup_workers(rh->context);
 714 }
 715 EXPORT_SYMBOL_GPL(dm_rh_start_recovery);
 716
 717 MODULE_DESCRIPTION(DM_NAME " region hash");
 718 MODULE_AUTHOR("Joe Thornber/Heinz Mauelshagen <dm-devel@redhat.com>");
 719 MODULE_LICENSE("GPL");