drivers/md/dm-thin-metadata.c

   1 /*
   2  * Copyright (C) 2011-2012 Red Hat, Inc.
   3  *
   4  * This file is released under the GPL.
   5  */
   6
   7 #include "dm-thin-metadata.h"
   8 #include "persistent-data/dm-btree.h"
   9 #include "persistent-data/dm-space-map.h"
  10 #include "persistent-data/dm-space-map-disk.h"
  11 #include "persistent-data/dm-transaction-manager.h"
  12
  13 #include <linux/list.h>
  14 #include <linux/device-mapper.h>
  15 #include <linux/workqueue.h>
  16
  17 /*--------------------------------------------------------------------------
  18  * As far as the metadata goes, there is:
  19  *
  20  * - A superblock in block zero, taking up fewer than 512 bytes for
  21  *   atomic writes.
  22  *
  23  * - A space map managing the metadata blocks.
  24  *
  25  * - A space map managing the data blocks.
  26  *
  27  * - A btree mapping our internal thin dev ids onto struct disk_device_details.
  28  *
  29  * - A hierarchical btree, with 2 levels which effectively maps (thin
  30  *   dev id, virtual block) -> block_time.  Block time is a 64-bit
  31  *   field holding the time in the low 24 bits, and block in the top 40
  32  *   bits.
  33  *
  34  * BTrees consist solely of btree_nodes, that fill a block.  Some are
  35  * internal nodes, as such their values are a __le64 pointing to other
  36  * nodes.  Leaf nodes can store data of any reasonable size (ie. much
  37  * smaller than the block size).  The nodes consist of the header,
  38  * followed by an array of keys, followed by an array of values.  We have
  39  * to binary search on the keys so they're all held together to help the
  40  * cpu cache.
  41  *
  42  * Space maps have 2 btrees:
  43  *
  44  * - One maps a uint64_t onto a struct index_entry.  Which points to a
  45  *   bitmap block, and has some details about how many free entries there
  46  *   are etc.
  47  *
  48  * - The bitmap blocks have a header (for the checksum).  Then the rest
  49  *   of the block is pairs of bits.  With the meaning being:
  50  *
  51  *   0 - ref count is 0
  52  *   1 - ref count is 1
  53  *   2 - ref count is 2
  54  *   3 - ref count is higher than 2
  55  *
  56  * - If the count is higher than 2 then the ref count is entered in a
  57  *   second btree that directly maps the block_address to a uint32_t ref
  58  *   count.
  59  *
  60  * The space map metadata variant doesn't have a bitmaps btree.  Instead
  61  * it has one single blocks worth of index_entries.  This avoids
  62  * recursive issues with the bitmap btree needing to allocate space in
  63  * order to insert.  With a small data block size such as 64k the
  64  * metadata support data devices that are hundreds of terrabytes.
  65  *
  66  * The space maps allocate space linearly from front to back.  Space that
  67  * is freed in a transaction is never recycled within that transaction.
  68  * To try and avoid fragmenting _free_ space the allocator always goes
  69  * back and fills in gaps.
  70  *
  71  * All metadata io is in THIN_METADATA_BLOCK_SIZE sized/aligned chunks
  72  * from the block manager.
  73  *--------------------------------------------------------------------------*/
  74
  75 #define DM_MSG_PREFIX   "thin metadata"
  76
  77 #define THIN_SUPERBLOCK_MAGIC 27022010
  78 #define THIN_SUPERBLOCK_LOCATION 0
  79 #define THIN_VERSION 2
  80 #define SECTOR_TO_BLOCK_SHIFT 3
  81
  82 /*
  83  * For btree insert:
  84  *  3 for btree insert +
  85  *  2 for btree lookup used within space map
  86  * For btree remove:
  87  *  2 for shadow spine +
  88  *  4 for rebalance 3 child node
  89  */
  90 #define THIN_MAX_CONCURRENT_LOCKS 6
  91
  92 /* This should be plenty */
  93 #define SPACE_MAP_ROOT_SIZE 128
  94
  95 /*
  96  * Little endian on-disk superblock and device details.
  97  */
  98 struct thin_disk_superblock {
  99         __le32 csum;    /* Checksum of superblock except for this field. */
 100         __le32 flags;
 101         __le64 blocknr; /* This block number, dm_block_t. */
 102
 103         __u8 uuid[16];
 104         __le64 magic;
 105         __le32 version;
 106         __le32 time;
 107
 108         __le64 trans_id;
 109
 110         /*
 111          * Root held by userspace transactions.
 112          */
 113         __le64 held_root;
 114
 115         __u8 data_space_map_root[SPACE_MAP_ROOT_SIZE];
 116         __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
 117
 118         /*
 119          * 2-level btree mapping (dev_id, (dev block, time)) -> data block
 120          */
 121         __le64 data_mapping_root;
 122
 123         /*
 124          * Device detail root mapping dev_id -> device_details
 125          */
 126         __le64 device_details_root;
 127
 128         __le32 data_block_size;         /* In 512-byte sectors. */
 129
 130         __le32 metadata_block_size;     /* In 512-byte sectors. */
 131         __le64 metadata_nr_blocks;
 132
 133         __le32 compat_flags;
 134         __le32 compat_ro_flags;
 135         __le32 incompat_flags;
 136 } __packed;
 137
 138 struct disk_device_details {
 139         __le64 mapped_blocks;
 140         __le64 transaction_id;          /* When created. */
 141         __le32 creation_time;
 142         __le32 snapshotted_time;
 143 } __packed;
 144
 145 struct dm_pool_metadata {
 146         struct hlist_node hash;
 147
 148         struct block_device *bdev;
 149         struct dm_block_manager *bm;
 150         struct dm_space_map *metadata_sm;
 151         struct dm_space_map *data_sm;
 152         struct dm_transaction_manager *tm;
 153         struct dm_transaction_manager *nb_tm;
 154
 155         /*
 156          * Two-level btree.
 157          * First level holds thin_dev_t.
 158          * Second level holds mappings.
 159          */
 160         struct dm_btree_info info;
 161
 162         /*
 163          * Non-blocking version of the above.
 164          */
 165         struct dm_btree_info nb_info;
 166
 167         /*
 168          * Just the top level for deleting whole devices.
 169          */
 170         struct dm_btree_info tl_info;
 171
 172         /*
 173          * Just the bottom level for creating new devices.
 174          */
 175         struct dm_btree_info bl_info;
 176
 177         /*
 178          * Describes the device details btree.
 179          */
 180         struct dm_btree_info details_info;
 181
 182         struct rw_semaphore root_lock;
 183         uint32_t time;
 184         dm_block_t root;
 185         dm_block_t details_root;
 186         struct list_head thin_devices;
 187         uint64_t trans_id;
 188         unsigned long flags;
 189         sector_t data_block_size;
 190
 191         /*
 192          * Pre-commit callback.
 193          *
 194          * This allows the thin provisioning target to run a callback before
 195          * the metadata are committed.
 196          */
 197         dm_pool_pre_commit_fn pre_commit_fn;
 198         void *pre_commit_context;
 199
 200         /*
 201          * We reserve a section of the metadata for commit overhead.
 202          * All reported space does *not* include this.
 203          */
 204         dm_block_t metadata_reserve;
 205
 206         /*
 207          * Set if a transaction has to be aborted but the attempt to roll back
 208          * to the previous (good) transaction failed.  The only pool metadata
 209          * operation possible in this state is the closing of the device.
 210          */
 211         bool fail_io:1;
 212
 213         /*
 214          * Set once a thin-pool has been accessed through one of the interfaces
 215          * that imply the pool is in-service (e.g. thin devices created/deleted,
 216          * thin-pool message, metadata snapshots, etc).
 217          */
 218         bool in_service:1;
 219
 220         /*
 221          * Reading the space map roots can fail, so we read it into these
 222          * buffers before the superblock is locked and updated.
 223          */
 224         __u8 data_space_map_root[SPACE_MAP_ROOT_SIZE];
 225         __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
 226 };
 227
 228 struct dm_thin_device {
 229         struct list_head list;
 230         struct dm_pool_metadata *pmd;
 231         dm_thin_id id;
 232
 233         int open_count;
 234         bool changed:1;
 235         bool aborted_with_changes:1;
 236         uint64_t mapped_blocks;
 237         uint64_t transaction_id;
 238         uint32_t creation_time;
 239         uint32_t snapshotted_time;
 240 };
 241
 242 /*----------------------------------------------------------------
 243  * superblock validator
 244  *--------------------------------------------------------------*/
 245
 246 #define SUPERBLOCK_CSUM_XOR 160774
 247
 248 static void sb_prepare_for_write(struct dm_block_validator *v,
 249                                  struct dm_block *b,
 250                                  size_t block_size)
 251 {
 252         struct thin_disk_superblock *disk_super = dm_block_data(b);
 253
 254         disk_super->blocknr = cpu_to_le64(dm_block_location(b));
 255         disk_super->csum = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
 256                                                       block_size - sizeof(__le32),
 257                                                       SUPERBLOCK_CSUM_XOR));
 258 }
 259
 260 static int sb_check(struct dm_block_validator *v,
 261                     struct dm_block *b,
 262                     size_t block_size)
 263 {
 264         struct thin_disk_superblock *disk_super = dm_block_data(b);
 265         __le32 csum_le;
 266
 267         if (dm_block_location(b) != le64_to_cpu(disk_super->blocknr)) {
 268                 DMERR("sb_check failed: blocknr %llu: "
 269                       "wanted %llu", le64_to_cpu(disk_super->blocknr),
 270                       (unsigned long long)dm_block_location(b));
 271                 return -ENOTBLK;
 272         }
 273
 274         if (le64_to_cpu(disk_super->magic) != THIN_SUPERBLOCK_MAGIC) {
 275                 DMERR("sb_check failed: magic %llu: "
 276                       "wanted %llu", le64_to_cpu(disk_super->magic),
 277                       (unsigned long long)THIN_SUPERBLOCK_MAGIC);
 278                 return -EILSEQ;
 279         }
 280
 281         csum_le = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
 282                                              block_size - sizeof(__le32),
 283                                              SUPERBLOCK_CSUM_XOR));
 284         if (csum_le != disk_super->csum) {
 285                 DMERR("sb_check failed: csum %u: wanted %u",
 286                       le32_to_cpu(csum_le), le32_to_cpu(disk_super->csum));
 287                 return -EILSEQ;
 288         }
 289
 290         return 0;
 291 }
 292
 293 static struct dm_block_validator sb_validator = {
 294         .name = "superblock",
 295         .prepare_for_write = sb_prepare_for_write,
 296         .check = sb_check
 297 };
 298
 299 /*----------------------------------------------------------------
 300  * Methods for the btree value types
 301  *--------------------------------------------------------------*/
 302
 303 static uint64_t pack_block_time(dm_block_t b, uint32_t t)
 304 {
 305         return (b << 24) | t;
 306 }
 307
 308 static void unpack_block_time(uint64_t v, dm_block_t *b, uint32_t *t)
 309 {
 310         *b = v >> 24;
 311         *t = v & ((1 << 24) - 1);
 312 }
 313
 314 static void data_block_inc(void *context, const void *value_le)
 315 {
 316         struct dm_space_map *sm = context;
 317         __le64 v_le;
 318         uint64_t b;
 319         uint32_t t;
 320
 321         memcpy(&v_le, value_le, sizeof(v_le));
 322         unpack_block_time(le64_to_cpu(v_le), &b, &t);
 323         dm_sm_inc_block(sm, b);
 324 }
 325
 326 static void data_block_dec(void *context, const void *value_le)
 327 {
 328         struct dm_space_map *sm = context;
 329         __le64 v_le;
 330         uint64_t b;
 331         uint32_t t;
 332
 333         memcpy(&v_le, value_le, sizeof(v_le));
 334         unpack_block_time(le64_to_cpu(v_le), &b, &t);
 335         dm_sm_dec_block(sm, b);
 336 }
 337
 338 static int data_block_equal(void *context, const void *value1_le, const void *value2_le)
 339 {
 340         __le64 v1_le, v2_le;
 341         uint64_t b1, b2;
 342         uint32_t t;
 343
 344         memcpy(&v1_le, value1_le, sizeof(v1_le));
 345         memcpy(&v2_le, value2_le, sizeof(v2_le));
 346         unpack_block_time(le64_to_cpu(v1_le), &b1, &t);
 347         unpack_block_time(le64_to_cpu(v2_le), &b2, &t);
 348
 349         return b1 == b2;
 350 }
 351
 352 static void subtree_inc(void *context, const void *value)
 353 {
 354         struct dm_btree_info *info = context;
 355         __le64 root_le;
 356         uint64_t root;
 357
 358         memcpy(&root_le, value, sizeof(root_le));
 359         root = le64_to_cpu(root_le);
 360         dm_tm_inc(info->tm, root);
 361 }
 362
 363 static void subtree_dec(void *context, const void *value)
 364 {
 365         struct dm_btree_info *info = context;
 366         __le64 root_le;
 367         uint64_t root;
 368
 369         memcpy(&root_le, value, sizeof(root_le));
 370         root = le64_to_cpu(root_le);
 371         if (dm_btree_del(info, root))
 372                 DMERR("btree delete failed");
 373 }
 374
 375 static int subtree_equal(void *context, const void *value1_le, const void *value2_le)
 376 {
 377         __le64 v1_le, v2_le;
 378         memcpy(&v1_le, value1_le, sizeof(v1_le));
 379         memcpy(&v2_le, value2_le, sizeof(v2_le));
 380
 381         return v1_le == v2_le;
 382 }
 383
 384 /*----------------------------------------------------------------*/
 385
 386 /*
 387  * Variant that is used for in-core only changes or code that
 388  * shouldn't put the pool in service on its own (e.g. commit).
 389  */
 390 static inline void pmd_write_lock_in_core(struct dm_pool_metadata *pmd)
 391         __acquires(pmd->root_lock)
 392 {
 393         down_write(&pmd->root_lock);
 394 }
 395
 396 static inline void pmd_write_lock(struct dm_pool_metadata *pmd)
 397 {
 398         pmd_write_lock_in_core(pmd);
 399         if (unlikely(!pmd->in_service))
 400                 pmd->in_service = true;
 401 }
 402
 403 static inline void pmd_write_unlock(struct dm_pool_metadata *pmd)
 404         __releases(pmd->root_lock)
 405 {
 406         up_write(&pmd->root_lock);
 407 }
 408
 409 /*----------------------------------------------------------------*/
 410
 411 static int superblock_lock_zero(struct dm_pool_metadata *pmd,
 412                                 struct dm_block **sblock)
 413 {
 414         return dm_bm_write_lock_zero(pmd->bm, THIN_SUPERBLOCK_LOCATION,
 415                                      &sb_validator, sblock);
 416 }
 417
 418 static int superblock_lock(struct dm_pool_metadata *pmd,
 419                            struct dm_block **sblock)
 420 {
 421         return dm_bm_write_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION,
 422                                 &sb_validator, sblock);
 423 }
 424
 425 static int __superblock_all_zeroes(struct dm_block_manager *bm, int *result)
 426 {
 427         int r;
 428         unsigned i;
 429         struct dm_block *b;
 430         __le64 *data_le, zero = cpu_to_le64(0);
 431         unsigned block_size = dm_bm_block_size(bm) / sizeof(__le64);
 432
 433         /*
 434          * We can't use a validator here - it may be all zeroes.
 435          */
 436         r = dm_bm_read_lock(bm, THIN_SUPERBLOCK_LOCATION, NULL, &b);
 437         if (r)
 438                 return r;
 439
 440         data_le = dm_block_data(b);
 441         *result = 1;
 442         for (i = 0; i < block_size; i++) {
 443                 if (data_le[i] != zero) {
 444                         *result = 0;
 445                         break;
 446                 }
 447         }
 448
 449         dm_bm_unlock(b);
 450
 451         return 0;
 452 }
 453
 454 static void __setup_btree_details(struct dm_pool_metadata *pmd)
 455 {
 456         pmd->info.tm = pmd->tm;
 457         pmd->info.levels = 2;
 458         pmd->info.value_type.context = pmd->data_sm;
 459         pmd->info.value_type.size = sizeof(__le64);
 460         pmd->info.value_type.inc = data_block_inc;
 461         pmd->info.value_type.dec = data_block_dec;
 462         pmd->info.value_type.equal = data_block_equal;
 463
 464         memcpy(&pmd->nb_info, &pmd->info, sizeof(pmd->nb_info));
 465         pmd->nb_info.tm = pmd->nb_tm;
 466
 467         pmd->tl_info.tm = pmd->tm;
 468         pmd->tl_info.levels = 1;
 469         pmd->tl_info.value_type.context = &pmd->bl_info;
 470         pmd->tl_info.value_type.size = sizeof(__le64);
 471         pmd->tl_info.value_type.inc = subtree_inc;
 472         pmd->tl_info.value_type.dec = subtree_dec;
 473         pmd->tl_info.value_type.equal = subtree_equal;
 474
 475         pmd->bl_info.tm = pmd->tm;
 476         pmd->bl_info.levels = 1;
 477         pmd->bl_info.value_type.context = pmd->data_sm;
 478         pmd->bl_info.value_type.size = sizeof(__le64);
 479         pmd->bl_info.value_type.inc = data_block_inc;
 480         pmd->bl_info.value_type.dec = data_block_dec;
 481         pmd->bl_info.value_type.equal = data_block_equal;
 482
 483         pmd->details_info.tm = pmd->tm;
 484         pmd->details_info.levels = 1;
 485         pmd->details_info.value_type.context = NULL;
 486         pmd->details_info.value_type.size = sizeof(struct disk_device_details);
 487         pmd->details_info.value_type.inc = NULL;
 488         pmd->details_info.value_type.dec = NULL;
 489         pmd->details_info.value_type.equal = NULL;
 490 }
 491
 492 static int save_sm_roots(struct dm_pool_metadata *pmd)
 493 {
 494         int r;
 495         size_t len;
 496
 497         r = dm_sm_root_size(pmd->metadata_sm, &len);
 498         if (r < 0)
 499                 return r;
 500
 501         r = dm_sm_copy_root(pmd->metadata_sm, &pmd->metadata_space_map_root, len);
 502         if (r < 0)
 503                 return r;
 504
 505         r = dm_sm_root_size(pmd->data_sm, &len);
 506         if (r < 0)
 507                 return r;
 508
 509         return dm_sm_copy_root(pmd->data_sm, &pmd->data_space_map_root, len);
 510 }
 511
 512 static void copy_sm_roots(struct dm_pool_metadata *pmd,
 513                           struct thin_disk_superblock *disk)
 514 {
 515         memcpy(&disk->metadata_space_map_root,
 516                &pmd->metadata_space_map_root,
 517                sizeof(pmd->metadata_space_map_root));
 518
 519         memcpy(&disk->data_space_map_root,
 520                &pmd->data_space_map_root,
 521                sizeof(pmd->data_space_map_root));
 522 }
 523
 524 static int __write_initial_superblock(struct dm_pool_metadata *pmd)
 525 {
 526         int r;
 527         struct dm_block *sblock;
 528         struct thin_disk_superblock *disk_super;
 529         sector_t bdev_size = i_size_read(pmd->bdev->bd_inode) >> SECTOR_SHIFT;
 530
 531         if (bdev_size > THIN_METADATA_MAX_SECTORS)
 532                 bdev_size = THIN_METADATA_MAX_SECTORS;
 533
 534         r = dm_sm_commit(pmd->data_sm);
 535         if (r < 0)
 536                 return r;
 537
 538         r = dm_tm_pre_commit(pmd->tm);
 539         if (r < 0)
 540                 return r;
 541
 542         r = save_sm_roots(pmd);
 543         if (r < 0)
 544                 return r;
 545
 546         r = superblock_lock_zero(pmd, &sblock);
 547         if (r)
 548                 return r;
 549
 550         disk_super = dm_block_data(sblock);
 551         disk_super->flags = 0;
 552         memset(disk_super->uuid, 0, sizeof(disk_super->uuid));
 553         disk_super->magic = cpu_to_le64(THIN_SUPERBLOCK_MAGIC);
 554         disk_super->version = cpu_to_le32(THIN_VERSION);
 555         disk_super->time = 0;
 556         disk_super->trans_id = 0;
 557         disk_super->held_root = 0;
 558
 559         copy_sm_roots(pmd, disk_super);
 560
 561         disk_super->data_mapping_root = cpu_to_le64(pmd->root);
 562         disk_super->device_details_root = cpu_to_le64(pmd->details_root);
 563         disk_super->metadata_block_size = cpu_to_le32(THIN_METADATA_BLOCK_SIZE);
 564         disk_super->metadata_nr_blocks = cpu_to_le64(bdev_size >> SECTOR_TO_BLOCK_SHIFT);
 565         disk_super->data_block_size = cpu_to_le32(pmd->data_block_size);
 566
 567         return dm_tm_commit(pmd->tm, sblock);
 568 }
 569
 570 static int __format_metadata(struct dm_pool_metadata *pmd)
 571 {
 572         int r;
 573
 574         r = dm_tm_create_with_sm(pmd->bm, THIN_SUPERBLOCK_LOCATION,
 575                                  &pmd->tm, &pmd->metadata_sm);
 576         if (r < 0) {
 577                 DMERR("tm_create_with_sm failed");
 578                 return r;
 579         }
 580
 581         pmd->data_sm = dm_sm_disk_create(pmd->tm, 0);
 582         if (IS_ERR(pmd->data_sm)) {
 583                 DMERR("sm_disk_create failed");
 584                 r = PTR_ERR(pmd->data_sm);
 585                 goto bad_cleanup_tm;
 586         }
 587
 588         pmd->nb_tm = dm_tm_create_non_blocking_clone(pmd->tm);
 589         if (!pmd->nb_tm) {
 590                 DMERR("could not create non-blocking clone tm");
 591                 r = -ENOMEM;
 592                 goto bad_cleanup_data_sm;
 593         }
 594
 595         __setup_btree_details(pmd);
 596
 597         r = dm_btree_empty(&pmd->info, &pmd->root);
 598         if (r < 0)
 599                 goto bad_cleanup_nb_tm;
 600
 601         r = dm_btree_empty(&pmd->details_info, &pmd->details_root);
 602         if (r < 0) {
 603                 DMERR("couldn't create devices root");
 604                 goto bad_cleanup_nb_tm;
 605         }
 606
 607         r = __write_initial_superblock(pmd);
 608         if (r)
 609                 goto bad_cleanup_nb_tm;
 610
 611         return 0;
 612
 613 bad_cleanup_nb_tm:
 614         dm_tm_destroy(pmd->nb_tm);
 615 bad_cleanup_data_sm:
 616         dm_sm_destroy(pmd->data_sm);
 617 bad_cleanup_tm:
 618         dm_tm_destroy(pmd->tm);
 619         dm_sm_destroy(pmd->metadata_sm);
 620
 621         return r;
 622 }
 623
 624 static int __check_incompat_features(struct thin_disk_superblock *disk_super,
 625                                      struct dm_pool_metadata *pmd)
 626 {
 627         uint32_t features;
 628
 629         features = le32_to_cpu(disk_super->incompat_flags) & ~THIN_FEATURE_INCOMPAT_SUPP;
 630         if (features) {
 631                 DMERR("could not access metadata due to unsupported optional features (%lx).",
 632                       (unsigned long)features);
 633                 return -EINVAL;
 634         }
 635
 636         /*
 637          * Check for read-only metadata to skip the following RDWR checks.
 638          */
 639         if (get_disk_ro(pmd->bdev->bd_disk))
 640                 return 0;
 641
 642         features = le32_to_cpu(disk_super->compat_ro_flags) & ~THIN_FEATURE_COMPAT_RO_SUPP;
 643         if (features) {
 644                 DMERR("could not access metadata RDWR due to unsupported optional features (%lx).",
 645                       (unsigned long)features);
 646                 return -EINVAL;
 647         }
 648
 649         return 0;
 650 }
 651
 652 static int __open_metadata(struct dm_pool_metadata *pmd)
 653 {
 654         int r;
 655         struct dm_block *sblock;
 656         struct thin_disk_superblock *disk_super;
 657
 658         r = dm_bm_read_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION,
 659                             &sb_validator, &sblock);
 660         if (r < 0) {
 661                 DMERR("couldn't read superblock");
 662                 return r;
 663         }
 664
 665         disk_super = dm_block_data(sblock);
 666
 667         /* Verify the data block size hasn't changed */
 668         if (le32_to_cpu(disk_super->data_block_size) != pmd->data_block_size) {
 669                 DMERR("changing the data block size (from %u to %llu) is not supported",
 670                       le32_to_cpu(disk_super->data_block_size),
 671                       (unsigned long long)pmd->data_block_size);
 672                 r = -EINVAL;
 673                 goto bad_unlock_sblock;
 674         }
 675
 676         r = __check_incompat_features(disk_super, pmd);
 677         if (r < 0)
 678                 goto bad_unlock_sblock;
 679
 680         r = dm_tm_open_with_sm(pmd->bm, THIN_SUPERBLOCK_LOCATION,
 681                                disk_super->metadata_space_map_root,
 682                                sizeof(disk_super->metadata_space_map_root),
 683                                &pmd->tm, &pmd->metadata_sm);
 684         if (r < 0) {
 685                 DMERR("tm_open_with_sm failed");
 686                 goto bad_unlock_sblock;
 687         }
 688
 689         pmd->data_sm = dm_sm_disk_open(pmd->tm, disk_super->data_space_map_root,
 690                                        sizeof(disk_super->data_space_map_root));
 691         if (IS_ERR(pmd->data_sm)) {
 692                 DMERR("sm_disk_open failed");
 693                 r = PTR_ERR(pmd->data_sm);
 694                 goto bad_cleanup_tm;
 695         }
 696
 697         pmd->nb_tm = dm_tm_create_non_blocking_clone(pmd->tm);
 698         if (!pmd->nb_tm) {
 699                 DMERR("could not create non-blocking clone tm");
 700                 r = -ENOMEM;
 701                 goto bad_cleanup_data_sm;
 702         }
 703
 704         /*
 705          * For pool metadata opening process, root setting is redundant
 706          * because it will be set again in __begin_transaction(). But dm
 707          * pool aborting process really needs to get last transaction's
 708          * root to avoid accessing broken btree.
 709          */
 710         pmd->root = le64_to_cpu(disk_super->data_mapping_root);
 711         pmd->details_root = le64_to_cpu(disk_super->device_details_root);
 712
 713         __setup_btree_details(pmd);
 714         dm_bm_unlock(sblock);
 715
 716         return 0;
 717
 718 bad_cleanup_data_sm:
 719         dm_sm_destroy(pmd->data_sm);
 720 bad_cleanup_tm:
 721         dm_tm_destroy(pmd->tm);
 722         dm_sm_destroy(pmd->metadata_sm);
 723 bad_unlock_sblock:
 724         dm_bm_unlock(sblock);
 725
 726         return r;
 727 }
 728
 729 static int __open_or_format_metadata(struct dm_pool_metadata *pmd, bool format_device)
 730 {
 731         int r, unformatted;
 732
 733         r = __superblock_all_zeroes(pmd->bm, &unformatted);
 734         if (r)
 735                 return r;
 736
 737         if (unformatted)
 738                 return format_device ? __format_metadata(pmd) : -EPERM;
 739
 740         return __open_metadata(pmd);
 741 }
 742
 743 static int __create_persistent_data_objects(struct dm_pool_metadata *pmd, bool format_device)
 744 {
 745         int r;
 746
 747         pmd->bm = dm_block_manager_create(pmd->bdev, THIN_METADATA_BLOCK_SIZE << SECTOR_SHIFT,
 748                                           THIN_MAX_CONCURRENT_LOCKS);
 749         if (IS_ERR(pmd->bm)) {
 750                 DMERR("could not create block manager");
 751                 r = PTR_ERR(pmd->bm);
 752                 pmd->bm = NULL;
 753                 return r;
 754         }
 755
 756         r = __open_or_format_metadata(pmd, format_device);
 757         if (r) {
 758                 dm_block_manager_destroy(pmd->bm);
 759                 pmd->bm = NULL;
 760         }
 761
 762         return r;
 763 }
 764
 765 static void __destroy_persistent_data_objects(struct dm_pool_metadata *pmd,
 766                                               bool destroy_bm)
 767 {
 768         dm_sm_destroy(pmd->data_sm);
 769         dm_sm_destroy(pmd->metadata_sm);
 770         dm_tm_destroy(pmd->nb_tm);
 771         dm_tm_destroy(pmd->tm);
 772         if (destroy_bm)
 773                 dm_block_manager_destroy(pmd->bm);
 774 }
 775
 776 static int __begin_transaction(struct dm_pool_metadata *pmd)
 777 {
 778         int r;
 779         struct thin_disk_superblock *disk_super;
 780         struct dm_block *sblock;
 781
 782         /*
 783          * We re-read the superblock every time.  Shouldn't need to do this
 784          * really.
 785          */
 786         r = dm_bm_read_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION,
 787                             &sb_validator, &sblock);
 788         if (r)
 789                 return r;
 790
 791         disk_super = dm_block_data(sblock);
 792         pmd->time = le32_to_cpu(disk_super->time);
 793         pmd->root = le64_to_cpu(disk_super->data_mapping_root);
 794         pmd->details_root = le64_to_cpu(disk_super->device_details_root);
 795         pmd->trans_id = le64_to_cpu(disk_super->trans_id);
 796         pmd->flags = le32_to_cpu(disk_super->flags);
 797         pmd->data_block_size = le32_to_cpu(disk_super->data_block_size);
 798
 799         dm_bm_unlock(sblock);
 800         return 0;
 801 }
 802
 803 static int __write_changed_details(struct dm_pool_metadata *pmd)
 804 {
 805         int r;
 806         struct dm_thin_device *td, *tmp;
 807         struct disk_device_details details;
 808         uint64_t key;
 809
 810         list_for_each_entry_safe(td, tmp, &pmd->thin_devices, list) {
 811                 if (!td->changed)
 812                         continue;
 813
 814                 key = td->id;
 815
 816                 details.mapped_blocks = cpu_to_le64(td->mapped_blocks);
 817                 details.transaction_id = cpu_to_le64(td->transaction_id);
 818                 details.creation_time = cpu_to_le32(td->creation_time);
 819                 details.snapshotted_time = cpu_to_le32(td->snapshotted_time);
 820                 __dm_bless_for_disk(&details);
 821
 822                 r = dm_btree_insert(&pmd->details_info, pmd->details_root,
 823                                     &key, &details, &pmd->details_root);
 824                 if (r)
 825                         return r;
 826
 827                 if (td->open_count)
 828                         td->changed = false;
 829                 else {
 830                         list_del(&td->list);
 831                         kfree(td);
 832                 }
 833         }
 834
 835         return 0;
 836 }
 837
 838 static int __commit_transaction(struct dm_pool_metadata *pmd)
 839 {
 840         int r;
 841         struct thin_disk_superblock *disk_super;
 842         struct dm_block *sblock;
 843
 844         /*
 845          * We need to know if the thin_disk_superblock exceeds a 512-byte sector.
 846          */
 847         BUILD_BUG_ON(sizeof(struct thin_disk_superblock) > 512);
 848         BUG_ON(!rwsem_is_locked(&pmd->root_lock));
 849
 850         if (unlikely(!pmd->in_service))
 851                 return 0;
 852
 853         if (pmd->pre_commit_fn) {
 854                 r = pmd->pre_commit_fn(pmd->pre_commit_context);
 855                 if (r < 0) {
 856                         DMERR("pre-commit callback failed");
 857                         return r;
 858                 }
 859         }
 860
 861         r = __write_changed_details(pmd);
 862         if (r < 0)
 863                 return r;
 864
 865         r = dm_sm_commit(pmd->data_sm);
 866         if (r < 0)
 867                 return r;
 868
 869         r = dm_tm_pre_commit(pmd->tm);
 870         if (r < 0)
 871                 return r;
 872
 873         r = save_sm_roots(pmd);
 874         if (r < 0)
 875                 return r;
 876
 877         r = superblock_lock(pmd, &sblock);
 878         if (r)
 879                 return r;
 880
 881         disk_super = dm_block_data(sblock);
 882         disk_super->time = cpu_to_le32(pmd->time);
 883         disk_super->data_mapping_root = cpu_to_le64(pmd->root);
 884         disk_super->device_details_root = cpu_to_le64(pmd->details_root);
 885         disk_super->trans_id = cpu_to_le64(pmd->trans_id);
 886         disk_super->flags = cpu_to_le32(pmd->flags);
 887
 888         copy_sm_roots(pmd, disk_super);
 889
 890         return dm_tm_commit(pmd->tm, sblock);
 891 }
 892
 893 static void __set_metadata_reserve(struct dm_pool_metadata *pmd)
 894 {
 895         int r;
 896         dm_block_t total;
 897         dm_block_t max_blocks = 4096; /* 16M */
 898
 899         r = dm_sm_get_nr_blocks(pmd->metadata_sm, &total);
 900         if (r) {
 901                 DMERR("could not get size of metadata device");
 902                 pmd->metadata_reserve = max_blocks;
 903         } else
 904                 pmd->metadata_reserve = min(max_blocks, div_u64(total, 10));
 905 }
 906
 907 struct dm_pool_metadata *dm_pool_metadata_open(struct block_device *bdev,
 908                                                sector_t data_block_size,
 909                                                bool format_device)
 910 {
 911         int r;
 912         struct dm_pool_metadata *pmd;
 913
 914         pmd = kmalloc(sizeof(*pmd), GFP_KERNEL);
 915         if (!pmd) {
 916                 DMERR("could not allocate metadata struct");
 917                 return ERR_PTR(-ENOMEM);
 918         }
 919
 920         init_rwsem(&pmd->root_lock);
 921         pmd->time = 0;
 922         INIT_LIST_HEAD(&pmd->thin_devices);
 923         pmd->fail_io = false;
 924         pmd->in_service = false;
 925         pmd->bdev = bdev;
 926         pmd->data_block_size = data_block_size;
 927         pmd->pre_commit_fn = NULL;
 928         pmd->pre_commit_context = NULL;
 929
 930         r = __create_persistent_data_objects(pmd, format_device);
 931         if (r) {
 932                 kfree(pmd);
 933                 return ERR_PTR(r);
 934         }
 935
 936         r = __begin_transaction(pmd);
 937         if (r < 0) {
 938                 if (dm_pool_metadata_close(pmd) < 0)
 939                         DMWARN("%s: dm_pool_metadata_close() failed.", __func__);
 940                 return ERR_PTR(r);
 941         }
 942
 943         __set_metadata_reserve(pmd);
 944
 945         return pmd;
 946 }
 947
 948 int dm_pool_metadata_close(struct dm_pool_metadata *pmd)
 949 {
 950         int r;
 951         unsigned open_devices = 0;
 952         struct dm_thin_device *td, *tmp;
 953
 954         down_read(&pmd->root_lock);
 955         list_for_each_entry_safe(td, tmp, &pmd->thin_devices, list) {
 956                 if (td->open_count)
 957                         open_devices++;
 958                 else {
 959                         list_del(&td->list);
 960                         kfree(td);
 961                 }
 962         }
 963         up_read(&pmd->root_lock);
 964
 965         if (open_devices) {
 966                 DMERR("attempt to close pmd when %u device(s) are still open",
 967                        open_devices);
 968                 return -EBUSY;
 969         }
 970
 971         pmd_write_lock_in_core(pmd);
 972         if (!pmd->fail_io && !dm_bm_is_read_only(pmd->bm)) {
 973                 r = __commit_transaction(pmd);
 974                 if (r < 0)
 975                         DMWARN("%s: __commit_transaction() failed, error = %d",
 976                                __func__, r);
 977         }
 978         pmd_write_unlock(pmd);
 979         if (!pmd->fail_io)
 980                 __destroy_persistent_data_objects(pmd, true);
 981
 982         kfree(pmd);
 983         return 0;
 984 }
 985
 986 /*
 987  * __open_device: Returns @td corresponding to device with id @dev,
 988  * creating it if @create is set and incrementing @td->open_count.
 989  * On failure, @td is undefined.
 990  */
 991 static int __open_device(struct dm_pool_metadata *pmd,
 992                          dm_thin_id dev, int create,
 993                          struct dm_thin_device **td)
 994 {
 995         int r, changed = 0;
 996         struct dm_thin_device *td2;
 997         uint64_t key = dev;
 998         struct disk_device_details details_le;
 999
1000         /*
1001          * If the device is already open, return it.
1002          */
1003         list_for_each_entry(td2, &pmd->thin_devices, list)
1004                 if (td2->id == dev) {
1005                         /*
1006                          * May not create an already-open device.
1007                          */
1008                         if (create)
1009                                 return -EEXIST;
1010
1011                         td2->open_count++;
1012                         *td = td2;
1013                         return 0;
1014                 }
1015
1016         /*
1017          * Check the device exists.
1018          */
1019         r = dm_btree_lookup(&pmd->details_info, pmd->details_root,
1020                             &key, &details_le);
1021         if (r) {
1022                 if (r != -ENODATA || !create)
1023                         return r;
1024
1025                 /*
1026                  * Create new device.
1027                  */
1028                 changed = 1;
1029                 details_le.mapped_blocks = 0;
1030                 details_le.transaction_id = cpu_to_le64(pmd->trans_id);
1031                 details_le.creation_time = cpu_to_le32(pmd->time);
1032                 details_le.snapshotted_time = cpu_to_le32(pmd->time);
1033         }
1034
1035         *td = kmalloc(sizeof(**td), GFP_NOIO);
1036         if (!*td)
1037                 return -ENOMEM;
1038
1039         (*td)->pmd = pmd;
1040         (*td)->id = dev;
1041         (*td)->open_count = 1;
1042         (*td)->changed = changed;
1043         (*td)->aborted_with_changes = false;
1044         (*td)->mapped_blocks = le64_to_cpu(details_le.mapped_blocks);
1045         (*td)->transaction_id = le64_to_cpu(details_le.transaction_id);
1046         (*td)->creation_time = le32_to_cpu(details_le.creation_time);
1047         (*td)->snapshotted_time = le32_to_cpu(details_le.snapshotted_time);
1048
1049         list_add(&(*td)->list, &pmd->thin_devices);
1050
1051         return 0;
1052 }
1053
1054 static void __close_device(struct dm_thin_device *td)
1055 {
1056         --td->open_count;
1057 }
1058
1059 static int __create_thin(struct dm_pool_metadata *pmd,
1060                          dm_thin_id dev)
1061 {
1062         int r;
1063         dm_block_t dev_root;
1064         uint64_t key = dev;
1065         struct dm_thin_device *td;
1066         __le64 value;
1067
1068         r = dm_btree_lookup(&pmd->details_info, pmd->details_root,
1069                             &key, NULL);
1070         if (!r)
1071                 return -EEXIST;
1072
1073         /*
1074          * Create an empty btree for the mappings.
1075          */
1076         r = dm_btree_empty(&pmd->bl_info, &dev_root);
1077         if (r)
1078                 return r;
1079
1080         /*
1081          * Insert it into the main mapping tree.
1082          */
1083         value = cpu_to_le64(dev_root);
1084         __dm_bless_for_disk(&value);
1085         r = dm_btree_insert(&pmd->tl_info, pmd->root, &key, &value, &pmd->root);
1086         if (r) {
1087                 dm_btree_del(&pmd->bl_info, dev_root);
1088                 return r;
1089         }
1090
1091         r = __open_device(pmd, dev, 1, &td);
1092         if (r) {
1093                 dm_btree_remove(&pmd->tl_info, pmd->root, &key, &pmd->root);
1094                 dm_btree_del(&pmd->bl_info, dev_root);
1095                 return r;
1096         }
1097         __close_device(td);
1098
1099         return r;
1100 }
1101
1102 int dm_pool_create_thin(struct dm_pool_metadata *pmd, dm_thin_id dev)
1103 {
1104         int r = -EINVAL;
1105
1106         pmd_write_lock(pmd);
1107         if (!pmd->fail_io)
1108                 r = __create_thin(pmd, dev);
1109         pmd_write_unlock(pmd);
1110
1111         return r;
1112 }
1113
1114 static int __set_snapshot_details(struct dm_pool_metadata *pmd,
1115                                   struct dm_thin_device *snap,
1116                                   dm_thin_id origin, uint32_t time)
1117 {
1118         int r;
1119         struct dm_thin_device *td;
1120
1121         r = __open_device(pmd, origin, 0, &td);
1122         if (r)
1123                 return r;
1124
1125         td->changed = true;
1126         td->snapshotted_time = time;
1127
1128         snap->mapped_blocks = td->mapped_blocks;
1129         snap->snapshotted_time = time;
1130         __close_device(td);
1131
1132         return 0;
1133 }
1134
1135 static int __create_snap(struct dm_pool_metadata *pmd,
1136                          dm_thin_id dev, dm_thin_id origin)
1137 {
1138         int r;
1139         dm_block_t origin_root;
1140         uint64_t key = origin, dev_key = dev;
1141         struct dm_thin_device *td;
1142         __le64 value;
1143
1144         /* check this device is unused */
1145         r = dm_btree_lookup(&pmd->details_info, pmd->details_root,
1146                             &dev_key, NULL);
1147         if (!r)
1148                 return -EEXIST;
1149
1150         /* find the mapping tree for the origin */
1151         r = dm_btree_lookup(&pmd->tl_info, pmd->root, &key, &value);
1152         if (r)
1153                 return r;
1154         origin_root = le64_to_cpu(value);
1155
1156         /* clone the origin, an inc will do */
1157         dm_tm_inc(pmd->tm, origin_root);
1158
1159         /* insert into the main mapping tree */
1160         value = cpu_to_le64(origin_root);
1161         __dm_bless_for_disk(&value);
1162         key = dev;
1163         r = dm_btree_insert(&pmd->tl_info, pmd->root, &key, &value, &pmd->root);
1164         if (r) {
1165                 dm_tm_dec(pmd->tm, origin_root);
1166                 return r;
1167         }
1168
1169         pmd->time++;
1170
1171         r = __open_device(pmd, dev, 1, &td);
1172         if (r)
1173                 goto bad;
1174
1175         r = __set_snapshot_details(pmd, td, origin, pmd->time);
1176         __close_device(td);
1177
1178         if (r)
1179                 goto bad;
1180
1181         return 0;
1182
1183 bad:
1184         dm_btree_remove(&pmd->tl_info, pmd->root, &key, &pmd->root);
1185         dm_btree_remove(&pmd->details_info, pmd->details_root,
1186                         &key, &pmd->details_root);
1187         return r;
1188 }
1189
1190 int dm_pool_create_snap(struct dm_pool_metadata *pmd,
1191                                  dm_thin_id dev,
1192                                  dm_thin_id origin)
1193 {
1194         int r = -EINVAL;
1195
1196         pmd_write_lock(pmd);
1197         if (!pmd->fail_io)
1198                 r = __create_snap(pmd, dev, origin);
1199         pmd_write_unlock(pmd);
1200
1201         return r;
1202 }
1203
1204 static int __delete_device(struct dm_pool_metadata *pmd, dm_thin_id dev)
1205 {
1206         int r;
1207         uint64_t key = dev;
1208         struct dm_thin_device *td;
1209
1210         /* TODO: failure should mark the transaction invalid */
1211         r = __open_device(pmd, dev, 0, &td);
1212         if (r)
1213                 return r;
1214
1215         if (td->open_count > 1) {
1216                 __close_device(td);
1217                 return -EBUSY;
1218         }
1219
1220         list_del(&td->list);
1221         kfree(td);
1222         r = dm_btree_remove(&pmd->details_info, pmd->details_root,
1223                             &key, &pmd->details_root);
1224         if (r)
1225                 return r;
1226
1227         r = dm_btree_remove(&pmd->tl_info, pmd->root, &key, &pmd->root);
1228         if (r)
1229                 return r;
1230
1231         return 0;
1232 }
1233
1234 int dm_pool_delete_thin_device(struct dm_pool_metadata *pmd,
1235                                dm_thin_id dev)
1236 {
1237         int r = -EINVAL;
1238
1239         pmd_write_lock(pmd);
1240         if (!pmd->fail_io)
1241                 r = __delete_device(pmd, dev);
1242         pmd_write_unlock(pmd);
1243
1244         return r;
1245 }
1246
1247 int dm_pool_set_metadata_transaction_id(struct dm_pool_metadata *pmd,
1248                                         uint64_t current_id,
1249                                         uint64_t new_id)
1250 {
1251         int r = -EINVAL;
1252
1253         pmd_write_lock(pmd);
1254
1255         if (pmd->fail_io)
1256                 goto out;
1257
1258         if (pmd->trans_id != current_id) {
1259                 DMERR("mismatched transaction id");
1260                 goto out;
1261         }
1262
1263         pmd->trans_id = new_id;
1264         r = 0;
1265
1266 out:
1267         pmd_write_unlock(pmd);
1268
1269         return r;
1270 }
1271
1272 int dm_pool_get_metadata_transaction_id(struct dm_pool_metadata *pmd,
1273                                         uint64_t *result)
1274 {
1275         int r = -EINVAL;
1276
1277         down_read(&pmd->root_lock);
1278         if (!pmd->fail_io) {
1279                 *result = pmd->trans_id;
1280                 r = 0;
1281         }
1282         up_read(&pmd->root_lock);
1283
1284         return r;
1285 }
1286
1287 static int __reserve_metadata_snap(struct dm_pool_metadata *pmd)
1288 {
1289         int r, inc;
1290         struct thin_disk_superblock *disk_super;
1291         struct dm_block *copy, *sblock;
1292         dm_block_t held_root;
1293
1294         /*
1295          * We commit to ensure the btree roots which we increment in a
1296          * moment are up to date.
1297          */
1298         r = __commit_transaction(pmd);
1299         if (r < 0) {
1300                 DMWARN("%s: __commit_transaction() failed, error = %d",
1301                        __func__, r);
1302                 return r;
1303         }
1304
1305         /*
1306          * Copy the superblock.
1307          */
1308         dm_sm_inc_block(pmd->metadata_sm, THIN_SUPERBLOCK_LOCATION);
1309         r = dm_tm_shadow_block(pmd->tm, THIN_SUPERBLOCK_LOCATION,
1310                                &sb_validator, &copy, &inc);
1311         if (r)
1312                 return r;
1313
1314         BUG_ON(!inc);
1315
1316         held_root = dm_block_location(copy);
1317         disk_super = dm_block_data(copy);
1318
1319         if (le64_to_cpu(disk_super->held_root)) {
1320                 DMWARN("Pool metadata snapshot already exists: release this before taking another.");
1321
1322                 dm_tm_dec(pmd->tm, held_root);
1323                 dm_tm_unlock(pmd->tm, copy);
1324                 return -EBUSY;
1325         }
1326
1327         /*
1328          * Wipe the spacemap since we're not publishing this.
1329          */
1330         memset(&disk_super->data_space_map_root, 0,
1331                sizeof(disk_super->data_space_map_root));
1332         memset(&disk_super->metadata_space_map_root, 0,
1333                sizeof(disk_super->metadata_space_map_root));
1334
1335         /*
1336          * Increment the data structures that need to be preserved.
1337          */
1338         dm_tm_inc(pmd->tm, le64_to_cpu(disk_super->data_mapping_root));
1339         dm_tm_inc(pmd->tm, le64_to_cpu(disk_super->device_details_root));
1340         dm_tm_unlock(pmd->tm, copy);
1341
1342         /*
1343          * Write the held root into the superblock.
1344          */
1345         r = superblock_lock(pmd, &sblock);
1346         if (r) {
1347                 dm_tm_dec(pmd->tm, held_root);
1348                 return r;
1349         }
1350
1351         disk_super = dm_block_data(sblock);
1352         disk_super->held_root = cpu_to_le64(held_root);
1353         dm_bm_unlock(sblock);
1354         return 0;
1355 }
1356
1357 int dm_pool_reserve_metadata_snap(struct dm_pool_metadata *pmd)
1358 {
1359         int r = -EINVAL;
1360
1361         pmd_write_lock(pmd);
1362         if (!pmd->fail_io)
1363                 r = __reserve_metadata_snap(pmd);
1364         pmd_write_unlock(pmd);
1365
1366         return r;
1367 }
1368
1369 static int __release_metadata_snap(struct dm_pool_metadata *pmd)
1370 {
1371         int r;
1372         struct thin_disk_superblock *disk_super;
1373         struct dm_block *sblock, *copy;
1374         dm_block_t held_root;
1375
1376         r = superblock_lock(pmd, &sblock);
1377         if (r)
1378                 return r;
1379
1380         disk_super = dm_block_data(sblock);
1381         held_root = le64_to_cpu(disk_super->held_root);
1382         disk_super->held_root = cpu_to_le64(0);
1383
1384         dm_bm_unlock(sblock);
1385
1386         if (!held_root) {
1387                 DMWARN("No pool metadata snapshot found: nothing to release.");
1388                 return -EINVAL;
1389         }
1390
1391         r = dm_tm_read_lock(pmd->tm, held_root, &sb_validator, &copy);
1392         if (r)
1393                 return r;
1394
1395         disk_super = dm_block_data(copy);
1396         dm_btree_del(&pmd->info, le64_to_cpu(disk_super->data_mapping_root));
1397         dm_btree_del(&pmd->details_info, le64_to_cpu(disk_super->device_details_root));
1398         dm_sm_dec_block(pmd->metadata_sm, held_root);
1399
1400         dm_tm_unlock(pmd->tm, copy);
1401
1402         return 0;
1403 }
1404
1405 int dm_pool_release_metadata_snap(struct dm_pool_metadata *pmd)
1406 {
1407         int r = -EINVAL;
1408
1409         pmd_write_lock(pmd);
1410         if (!pmd->fail_io)
1411                 r = __release_metadata_snap(pmd);
1412         pmd_write_unlock(pmd);
1413
1414         return r;
1415 }
1416
1417 static int __get_metadata_snap(struct dm_pool_metadata *pmd,
1418                                dm_block_t *result)
1419 {
1420         int r;
1421         struct thin_disk_superblock *disk_super;
1422         struct dm_block *sblock;
1423
1424         r = dm_bm_read_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION,
1425                             &sb_validator, &sblock);
1426         if (r)
1427                 return r;
1428
1429         disk_super = dm_block_data(sblock);
1430         *result = le64_to_cpu(disk_super->held_root);
1431
1432         dm_bm_unlock(sblock);
1433
1434         return 0;
1435 }
1436
1437 int dm_pool_get_metadata_snap(struct dm_pool_metadata *pmd,
1438                               dm_block_t *result)
1439 {
1440         int r = -EINVAL;
1441
1442         down_read(&pmd->root_lock);
1443         if (!pmd->fail_io)
1444                 r = __get_metadata_snap(pmd, result);
1445         up_read(&pmd->root_lock);
1446
1447         return r;
1448 }
1449
1450 int dm_pool_open_thin_device(struct dm_pool_metadata *pmd, dm_thin_id dev,
1451                              struct dm_thin_device **td)
1452 {
1453         int r = -EINVAL;
1454
1455         pmd_write_lock_in_core(pmd);
1456         if (!pmd->fail_io)
1457                 r = __open_device(pmd, dev, 0, td);
1458         pmd_write_unlock(pmd);
1459
1460         return r;
1461 }
1462
1463 int dm_pool_close_thin_device(struct dm_thin_device *td)
1464 {
1465         pmd_write_lock_in_core(td->pmd);
1466         __close_device(td);
1467         pmd_write_unlock(td->pmd);
1468
1469         return 0;
1470 }
1471
1472 dm_thin_id dm_thin_dev_id(struct dm_thin_device *td)
1473 {
1474         return td->id;
1475 }
1476
1477 /*
1478  * Check whether @time (of block creation) is older than @td's last snapshot.
1479  * If so then the associated block is shared with the last snapshot device.
1480  * Any block on a device created *after* the device last got snapshotted is
1481  * necessarily not shared.
1482  */
1483 static bool __snapshotted_since(struct dm_thin_device *td, uint32_t time)
1484 {
1485         return td->snapshotted_time > time;
1486 }
1487
1488 static void unpack_lookup_result(struct dm_thin_device *td, __le64 value,
1489                                  struct dm_thin_lookup_result *result)
1490 {
1491         uint64_t block_time = 0;
1492         dm_block_t exception_block;
1493         uint32_t exception_time;
1494
1495         block_time = le64_to_cpu(value);
1496         unpack_block_time(block_time, &exception_block, &exception_time);
1497         result->block = exception_block;
1498         result->shared = __snapshotted_since(td, exception_time);
1499 }
1500
1501 static int __find_block(struct dm_thin_device *td, dm_block_t block,
1502                         int can_issue_io, struct dm_thin_lookup_result *result)
1503 {
1504         int r;
1505         __le64 value;
1506         struct dm_pool_metadata *pmd = td->pmd;
1507         dm_block_t keys[2] = { td->id, block };
1508         struct dm_btree_info *info;
1509
1510         if (can_issue_io) {
1511                 info = &pmd->info;
1512         } else
1513                 info = &pmd->nb_info;
1514
1515         r = dm_btree_lookup(info, pmd->root, keys, &value);
1516         if (!r)
1517                 unpack_lookup_result(td, value, result);
1518
1519         return r;
1520 }
1521
1522 int dm_thin_find_block(struct dm_thin_device *td, dm_block_t block,
1523                        int can_issue_io, struct dm_thin_lookup_result *result)
1524 {
1525         int r;
1526         struct dm_pool_metadata *pmd = td->pmd;
1527
1528         down_read(&pmd->root_lock);
1529         if (pmd->fail_io) {
1530                 up_read(&pmd->root_lock);
1531                 return -EINVAL;
1532         }
1533
1534         r = __find_block(td, block, can_issue_io, result);
1535
1536         up_read(&pmd->root_lock);
1537         return r;
1538 }
1539
1540 static int __find_next_mapped_block(struct dm_thin_device *td, dm_block_t block,
1541                                           dm_block_t *vblock,
1542                                           struct dm_thin_lookup_result *result)
1543 {
1544         int r;
1545         __le64 value;
1546         struct dm_pool_metadata *pmd = td->pmd;
1547         dm_block_t keys[2] = { td->id, block };
1548
1549         r = dm_btree_lookup_next(&pmd->info, pmd->root, keys, vblock, &value);
1550         if (!r)
1551                 unpack_lookup_result(td, value, result);
1552
1553         return r;
1554 }
1555
1556 static int __find_mapped_range(struct dm_thin_device *td,
1557                                dm_block_t begin, dm_block_t end,
1558                                dm_block_t *thin_begin, dm_block_t *thin_end,
1559                                dm_block_t *pool_begin, bool *maybe_shared)
1560 {
1561         int r;
1562         dm_block_t pool_end;
1563         struct dm_thin_lookup_result lookup;
1564
1565         if (end < begin)
1566                 return -ENODATA;
1567
1568         r = __find_next_mapped_block(td, begin, &begin, &lookup);
1569         if (r)
1570                 return r;
1571
1572         if (begin >= end)
1573                 return -ENODATA;
1574
1575         *thin_begin = begin;
1576         *pool_begin = lookup.block;
1577         *maybe_shared = lookup.shared;
1578
1579         begin++;
1580         pool_end = *pool_begin + 1;
1581         while (begin != end) {
1582                 r = __find_block(td, begin, true, &lookup);
1583                 if (r) {
1584                         if (r == -ENODATA)
1585                                 break;
1586                         else
1587                                 return r;
1588                 }
1589
1590                 if ((lookup.block != pool_end) ||
1591                     (lookup.shared != *maybe_shared))
1592                         break;
1593
1594                 pool_end++;
1595                 begin++;
1596         }
1597
1598         *thin_end = begin;
1599         return 0;
1600 }
1601
1602 int dm_thin_find_mapped_range(struct dm_thin_device *td,
1603                               dm_block_t begin, dm_block_t end,
1604                               dm_block_t *thin_begin, dm_block_t *thin_end,
1605                               dm_block_t *pool_begin, bool *maybe_shared)
1606 {
1607         int r = -EINVAL;
1608         struct dm_pool_metadata *pmd = td->pmd;
1609
1610         down_read(&pmd->root_lock);
1611         if (!pmd->fail_io) {
1612                 r = __find_mapped_range(td, begin, end, thin_begin, thin_end,
1613                                         pool_begin, maybe_shared);
1614         }
1615         up_read(&pmd->root_lock);
1616
1617         return r;
1618 }
1619
1620 static int __insert(struct dm_thin_device *td, dm_block_t block,
1621                     dm_block_t data_block)
1622 {
1623         int r, inserted;
1624         __le64 value;
1625         struct dm_pool_metadata *pmd = td->pmd;
1626         dm_block_t keys[2] = { td->id, block };
1627
1628         value = cpu_to_le64(pack_block_time(data_block, pmd->time));
1629         __dm_bless_for_disk(&value);
1630
1631         r = dm_btree_insert_notify(&pmd->info, pmd->root, keys, &value,
1632                                    &pmd->root, &inserted);
1633         if (r)
1634                 return r;
1635
1636         td->changed = true;
1637         if (inserted)
1638                 td->mapped_blocks++;
1639
1640         return 0;
1641 }
1642
1643 int dm_thin_insert_block(struct dm_thin_device *td, dm_block_t block,
1644                          dm_block_t data_block)
1645 {
1646         int r = -EINVAL;
1647
1648         pmd_write_lock(td->pmd);
1649         if (!td->pmd->fail_io)
1650                 r = __insert(td, block, data_block);
1651         pmd_write_unlock(td->pmd);
1652
1653         return r;
1654 }
1655
1656 static int __remove(struct dm_thin_device *td, dm_block_t block)
1657 {
1658         int r;
1659         struct dm_pool_metadata *pmd = td->pmd;
1660         dm_block_t keys[2] = { td->id, block };
1661
1662         r = dm_btree_remove(&pmd->info, pmd->root, keys, &pmd->root);
1663         if (r)
1664                 return r;
1665
1666         td->mapped_blocks--;
1667         td->changed = true;
1668
1669         return 0;
1670 }
1671
1672 static int __remove_range(struct dm_thin_device *td, dm_block_t begin, dm_block_t end)
1673 {
1674         int r;
1675         unsigned count, total_count = 0;
1676         struct dm_pool_metadata *pmd = td->pmd;
1677         dm_block_t keys[1] = { td->id };
1678         __le64 value;
1679         dm_block_t mapping_root;
1680
1681         /*
1682          * Find the mapping tree
1683          */
1684         r = dm_btree_lookup(&pmd->tl_info, pmd->root, keys, &value);
1685         if (r)
1686                 return r;
1687
1688         /*
1689          * Remove from the mapping tree, taking care to inc the
1690          * ref count so it doesn't get deleted.
1691          */
1692         mapping_root = le64_to_cpu(value);
1693         dm_tm_inc(pmd->tm, mapping_root);
1694         r = dm_btree_remove(&pmd->tl_info, pmd->root, keys, &pmd->root);
1695         if (r)
1696                 return r;
1697
1698         /*
1699          * Remove leaves stops at the first unmapped entry, so we have to
1700          * loop round finding mapped ranges.
1701          */
1702         while (begin < end) {
1703                 r = dm_btree_lookup_next(&pmd->bl_info, mapping_root, &begin, &begin, &value);
1704                 if (r == -ENODATA)
1705                         break;
1706
1707                 if (r)
1708                         return r;
1709
1710                 if (begin >= end)
1711                         break;
1712
1713                 r = dm_btree_remove_leaves(&pmd->bl_info, mapping_root, &begin, end, &mapping_root, &count);
1714                 if (r)
1715                         return r;
1716
1717                 total_count += count;
1718         }
1719
1720         td->mapped_blocks -= total_count;
1721         td->changed = true;
1722
1723         /*
1724          * Reinsert the mapping tree.
1725          */
1726         value = cpu_to_le64(mapping_root);
1727         __dm_bless_for_disk(&value);
1728         return dm_btree_insert(&pmd->tl_info, pmd->root, keys, &value, &pmd->root);
1729 }
1730
1731 int dm_thin_remove_block(struct dm_thin_device *td, dm_block_t block)
1732 {
1733         int r = -EINVAL;
1734
1735         pmd_write_lock(td->pmd);
1736         if (!td->pmd->fail_io)
1737                 r = __remove(td, block);
1738         pmd_write_unlock(td->pmd);
1739
1740         return r;
1741 }
1742
1743 int dm_thin_remove_range(struct dm_thin_device *td,
1744                          dm_block_t begin, dm_block_t end)
1745 {
1746         int r = -EINVAL;
1747
1748         pmd_write_lock(td->pmd);
1749         if (!td->pmd->fail_io)
1750                 r = __remove_range(td, begin, end);
1751         pmd_write_unlock(td->pmd);
1752
1753         return r;
1754 }
1755
1756 int dm_pool_block_is_shared(struct dm_pool_metadata *pmd, dm_block_t b, bool *result)
1757 {
1758         int r;
1759         uint32_t ref_count;
1760
1761         down_read(&pmd->root_lock);
1762         r = dm_sm_get_count(pmd->data_sm, b, &ref_count);
1763         if (!r)
1764                 *result = (ref_count > 1);
1765         up_read(&pmd->root_lock);
1766
1767         return r;
1768 }
1769
1770 int dm_pool_inc_data_range(struct dm_pool_metadata *pmd, dm_block_t b, dm_block_t e)
1771 {
1772         int r = 0;
1773
1774         pmd_write_lock(pmd);
1775         for (; b != e; b++) {
1776                 r = dm_sm_inc_block(pmd->data_sm, b);
1777                 if (r)
1778                         break;
1779         }
1780         pmd_write_unlock(pmd);
1781
1782         return r;
1783 }
1784
1785 int dm_pool_dec_data_range(struct dm_pool_metadata *pmd, dm_block_t b, dm_block_t e)
1786 {
1787         int r = 0;
1788
1789         pmd_write_lock(pmd);
1790         for (; b != e; b++) {
1791                 r = dm_sm_dec_block(pmd->data_sm, b);
1792                 if (r)
1793                         break;
1794         }
1795         pmd_write_unlock(pmd);
1796
1797         return r;
1798 }
1799
1800 bool dm_thin_changed_this_transaction(struct dm_thin_device *td)
1801 {
1802         int r;
1803
1804         down_read(&td->pmd->root_lock);
1805         r = td->changed;
1806         up_read(&td->pmd->root_lock);
1807
1808         return r;
1809 }
1810
1811 bool dm_pool_changed_this_transaction(struct dm_pool_metadata *pmd)
1812 {
1813         bool r = false;
1814         struct dm_thin_device *td, *tmp;
1815
1816         down_read(&pmd->root_lock);
1817         list_for_each_entry_safe(td, tmp, &pmd->thin_devices, list) {
1818                 if (td->changed) {
1819                         r = td->changed;
1820                         break;
1821                 }
1822         }
1823         up_read(&pmd->root_lock);
1824
1825         return r;
1826 }
1827
1828 bool dm_thin_aborted_changes(struct dm_thin_device *td)
1829 {
1830         bool r;
1831
1832         down_read(&td->pmd->root_lock);
1833         r = td->aborted_with_changes;
1834         up_read(&td->pmd->root_lock);
1835
1836         return r;
1837 }
1838
1839 int dm_pool_alloc_data_block(struct dm_pool_metadata *pmd, dm_block_t *result)
1840 {
1841         int r = -EINVAL;
1842
1843         pmd_write_lock(pmd);
1844         if (!pmd->fail_io)
1845                 r = dm_sm_new_block(pmd->data_sm, result);
1846         pmd_write_unlock(pmd);
1847
1848         return r;
1849 }
1850
1851 int dm_pool_commit_metadata(struct dm_pool_metadata *pmd)
1852 {
1853         int r = -EINVAL;
1854
1855         /*
1856          * Care is taken to not have commit be what
1857          * triggers putting the thin-pool in-service.
1858          */
1859         pmd_write_lock_in_core(pmd);
1860         if (pmd->fail_io)
1861                 goto out;
1862
1863         r = __commit_transaction(pmd);
1864         if (r < 0)
1865                 goto out;
1866
1867         /*
1868          * Open the next transaction.
1869          */
1870         r = __begin_transaction(pmd);
1871 out:
1872         pmd_write_unlock(pmd);
1873         return r;
1874 }
1875
1876 static void __set_abort_with_changes_flags(struct dm_pool_metadata *pmd)
1877 {
1878         struct dm_thin_device *td;
1879
1880         list_for_each_entry(td, &pmd->thin_devices, list)
1881                 td->aborted_with_changes = td->changed;
1882 }
1883
1884 int dm_pool_abort_metadata(struct dm_pool_metadata *pmd)
1885 {
1886         int r = -EINVAL;
1887         struct dm_block_manager *old_bm = NULL, *new_bm = NULL;
1888
1889         /* fail_io is double-checked with pmd->root_lock held below */
1890         if (unlikely(pmd->fail_io))
1891                 return r;
1892
1893         /*
1894          * Replacement block manager (new_bm) is created and old_bm destroyed outside of
1895          * pmd root_lock to avoid ABBA deadlock that would result (due to life-cycle of
1896          * shrinker associated with the block manager's bufio client vs pmd root_lock).
1897          * - must take shrinker_rwsem without holding pmd->root_lock
1898          */
1899         new_bm = dm_block_manager_create(pmd->bdev, THIN_METADATA_BLOCK_SIZE << SECTOR_SHIFT,
1900                                          THIN_MAX_CONCURRENT_LOCKS);
1901
1902         pmd_write_lock(pmd);
1903         if (pmd->fail_io) {
1904                 pmd_write_unlock(pmd);
1905                 goto out;
1906         }
1907
1908         __set_abort_with_changes_flags(pmd);
1909         __destroy_persistent_data_objects(pmd, false);
1910         old_bm = pmd->bm;
1911         if (IS_ERR(new_bm)) {
1912                 DMERR("could not create block manager during abort");
1913                 pmd->bm = NULL;
1914                 r = PTR_ERR(new_bm);
1915                 goto out_unlock;
1916         }
1917
1918         pmd->bm = new_bm;
1919         r = __open_or_format_metadata(pmd, false);
1920         if (r) {
1921                 pmd->bm = NULL;
1922                 goto out_unlock;
1923         }
1924         new_bm = NULL;
1925 out_unlock:
1926         if (r)
1927                 pmd->fail_io = true;
1928         pmd_write_unlock(pmd);
1929         dm_block_manager_destroy(old_bm);
1930 out:
1931         if (new_bm && !IS_ERR(new_bm))
1932                 dm_block_manager_destroy(new_bm);
1933
1934         return r;
1935 }
1936
1937 int dm_pool_get_free_block_count(struct dm_pool_metadata *pmd, dm_block_t *result)
1938 {
1939         int r = -EINVAL;
1940
1941         down_read(&pmd->root_lock);
1942         if (!pmd->fail_io)
1943                 r = dm_sm_get_nr_free(pmd->data_sm, result);
1944         up_read(&pmd->root_lock);
1945
1946         return r;
1947 }
1948
1949 int dm_pool_get_free_metadata_block_count(struct dm_pool_metadata *pmd,
1950                                           dm_block_t *result)
1951 {
1952         int r = -EINVAL;
1953
1954         down_read(&pmd->root_lock);
1955         if (!pmd->fail_io)
1956                 r = dm_sm_get_nr_free(pmd->metadata_sm, result);
1957
1958         if (!r) {
1959                 if (*result < pmd->metadata_reserve)
1960                         *result = 0;
1961                 else
1962                         *result -= pmd->metadata_reserve;
1963         }
1964         up_read(&pmd->root_lock);
1965
1966         return r;
1967 }
1968
1969 int dm_pool_get_metadata_dev_size(struct dm_pool_metadata *pmd,
1970                                   dm_block_t *result)
1971 {
1972         int r = -EINVAL;
1973
1974         down_read(&pmd->root_lock);
1975         if (!pmd->fail_io)
1976                 r = dm_sm_get_nr_blocks(pmd->metadata_sm, result);
1977         up_read(&pmd->root_lock);
1978
1979         return r;
1980 }
1981
1982 int dm_pool_get_data_dev_size(struct dm_pool_metadata *pmd, dm_block_t *result)
1983 {
1984         int r = -EINVAL;
1985
1986         down_read(&pmd->root_lock);
1987         if (!pmd->fail_io)
1988                 r = dm_sm_get_nr_blocks(pmd->data_sm, result);
1989         up_read(&pmd->root_lock);
1990
1991         return r;
1992 }
1993
1994 int dm_thin_get_mapped_count(struct dm_thin_device *td, dm_block_t *result)
1995 {
1996         int r = -EINVAL;
1997         struct dm_pool_metadata *pmd = td->pmd;
1998
1999         down_read(&pmd->root_lock);
2000         if (!pmd->fail_io) {
2001                 *result = td->mapped_blocks;
2002                 r = 0;
2003         }
2004         up_read(&pmd->root_lock);
2005
2006         return r;
2007 }
2008
2009 static int __highest_block(struct dm_thin_device *td, dm_block_t *result)
2010 {
2011         int r;
2012         __le64 value_le;
2013         dm_block_t thin_root;
2014         struct dm_pool_metadata *pmd = td->pmd;
2015
2016         r = dm_btree_lookup(&pmd->tl_info, pmd->root, &td->id, &value_le);
2017         if (r)
2018                 return r;
2019
2020         thin_root = le64_to_cpu(value_le);
2021
2022         return dm_btree_find_highest_key(&pmd->bl_info, thin_root, result);
2023 }
2024
2025 int dm_thin_get_highest_mapped_block(struct dm_thin_device *td,
2026                                      dm_block_t *result)
2027 {
2028         int r = -EINVAL;
2029         struct dm_pool_metadata *pmd = td->pmd;
2030
2031         down_read(&pmd->root_lock);
2032         if (!pmd->fail_io)
2033                 r = __highest_block(td, result);
2034         up_read(&pmd->root_lock);
2035
2036         return r;
2037 }
2038
2039 static int __resize_space_map(struct dm_space_map *sm, dm_block_t new_count)
2040 {
2041         int r;
2042         dm_block_t old_count;
2043
2044         r = dm_sm_get_nr_blocks(sm, &old_count);
2045         if (r)
2046                 return r;
2047
2048         if (new_count == old_count)
2049                 return 0;
2050
2051         if (new_count < old_count) {
2052                 DMERR("cannot reduce size of space map");
2053                 return -EINVAL;
2054         }
2055
2056         return dm_sm_extend(sm, new_count - old_count);
2057 }
2058
2059 int dm_pool_resize_data_dev(struct dm_pool_metadata *pmd, dm_block_t new_count)
2060 {
2061         int r = -EINVAL;
2062
2063         pmd_write_lock(pmd);
2064         if (!pmd->fail_io)
2065                 r = __resize_space_map(pmd->data_sm, new_count);
2066         pmd_write_unlock(pmd);
2067
2068         return r;
2069 }
2070
2071 int dm_pool_resize_metadata_dev(struct dm_pool_metadata *pmd, dm_block_t new_count)
2072 {
2073         int r = -EINVAL;
2074
2075         pmd_write_lock(pmd);
2076         if (!pmd->fail_io) {
2077                 r = __resize_space_map(pmd->metadata_sm, new_count);
2078                 if (!r)
2079                         __set_metadata_reserve(pmd);
2080         }
2081         pmd_write_unlock(pmd);
2082
2083         return r;
2084 }
2085
2086 void dm_pool_metadata_read_only(struct dm_pool_metadata *pmd)
2087 {
2088         pmd_write_lock_in_core(pmd);
2089         dm_bm_set_read_only(pmd->bm);
2090         pmd_write_unlock(pmd);
2091 }
2092
2093 void dm_pool_metadata_read_write(struct dm_pool_metadata *pmd)
2094 {
2095         pmd_write_lock_in_core(pmd);
2096         dm_bm_set_read_write(pmd->bm);
2097         pmd_write_unlock(pmd);
2098 }
2099
2100 int dm_pool_register_metadata_threshold(struct dm_pool_metadata *pmd,
2101                                         dm_block_t threshold,
2102                                         dm_sm_threshold_fn fn,
2103                                         void *context)
2104 {
2105         int r = -EINVAL;
2106
2107         pmd_write_lock_in_core(pmd);
2108         if (!pmd->fail_io) {
2109                 r = dm_sm_register_threshold_callback(pmd->metadata_sm,
2110                                                       threshold, fn, context);
2111         }
2112         pmd_write_unlock(pmd);
2113
2114         return r;
2115 }
2116
2117 void dm_pool_register_pre_commit_callback(struct dm_pool_metadata *pmd,
2118                                           dm_pool_pre_commit_fn fn,
2119                                           void *context)
2120 {
2121         pmd_write_lock_in_core(pmd);
2122         pmd->pre_commit_fn = fn;
2123         pmd->pre_commit_context = context;
2124         pmd_write_unlock(pmd);
2125 }
2126
2127 int dm_pool_metadata_set_needs_check(struct dm_pool_metadata *pmd)
2128 {
2129         int r = -EINVAL;
2130         struct dm_block *sblock;
2131         struct thin_disk_superblock *disk_super;
2132
2133         pmd_write_lock(pmd);
2134         if (pmd->fail_io)
2135                 goto out;
2136
2137         pmd->flags |= THIN_METADATA_NEEDS_CHECK_FLAG;
2138
2139         r = superblock_lock(pmd, &sblock);
2140         if (r) {
2141                 DMERR("couldn't lock superblock");
2142                 goto out;
2143         }
2144
2145         disk_super = dm_block_data(sblock);
2146         disk_super->flags = cpu_to_le32(pmd->flags);
2147
2148         dm_bm_unlock(sblock);
2149 out:
2150         pmd_write_unlock(pmd);
2151         return r;
2152 }
2153
2154 bool dm_pool_metadata_needs_check(struct dm_pool_metadata *pmd)
2155 {
2156         bool needs_check;
2157
2158         down_read(&pmd->root_lock);
2159         needs_check = pmd->flags & THIN_METADATA_NEEDS_CHECK_FLAG;
2160         up_read(&pmd->root_lock);
2161
2162         return needs_check;
2163 }
2164
2165 void dm_pool_issue_prefetches(struct dm_pool_metadata *pmd)
2166 {
2167         down_read(&pmd->root_lock);
2168         if (!pmd->fail_io)
2169                 dm_tm_issue_prefetches(pmd->tm);
2170         up_read(&pmd->root_lock);
2171 }