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