drivers/md/dm-cache-metadata.c

   1 /*
   2  * Copyright (C) 2012 Red Hat, Inc.
   3  *
   4  * This file is released under the GPL.
   5  */
   6
   7 #include "dm-cache-metadata.h"
   8
   9 #include "persistent-data/dm-array.h"
  10 #include "persistent-data/dm-bitset.h"
  11 #include "persistent-data/dm-space-map.h"
  12 #include "persistent-data/dm-space-map-disk.h"
  13 #include "persistent-data/dm-transaction-manager.h"
  14
  15 #include <linux/device-mapper.h>
  16 #include <linux/refcount.h>
  17
  18 /*----------------------------------------------------------------*/
  19
  20 #define DM_MSG_PREFIX   "cache metadata"
  21
  22 #define CACHE_SUPERBLOCK_MAGIC 06142003
  23 #define CACHE_SUPERBLOCK_LOCATION 0
  24
  25 /*
  26  * defines a range of metadata versions that this module can handle.
  27  */
  28 #define MIN_CACHE_VERSION 1
  29 #define MAX_CACHE_VERSION 2
  30
  31 /*
  32  *  3 for btree insert +
  33  *  2 for btree lookup used within space map
  34  */
  35 #define CACHE_MAX_CONCURRENT_LOCKS 5
  36 #define SPACE_MAP_ROOT_SIZE 128
  37
  38 enum superblock_flag_bits {
  39         /* for spotting crashes that would invalidate the dirty bitset */
  40         CLEAN_SHUTDOWN,
  41         /* metadata must be checked using the tools */
  42         NEEDS_CHECK,
  43 };
  44
  45 /*
  46  * Each mapping from cache block -> origin block carries a set of flags.
  47  */
  48 enum mapping_bits {
  49         /*
  50          * A valid mapping.  Because we're using an array we clear this
  51          * flag for an non existant mapping.
  52          */
  53         M_VALID = 1,
  54
  55         /*
  56          * The data on the cache is different from that on the origin.
  57          * This flag is only used by metadata format 1.
  58          */
  59         M_DIRTY = 2
  60 };
  61
  62 struct cache_disk_superblock {
  63         __le32 csum;
  64         __le32 flags;
  65         __le64 blocknr;
  66
  67         __u8 uuid[16];
  68         __le64 magic;
  69         __le32 version;
  70
  71         __u8 policy_name[CACHE_POLICY_NAME_SIZE];
  72         __le32 policy_hint_size;
  73
  74         __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
  75         __le64 mapping_root;
  76         __le64 hint_root;
  77
  78         __le64 discard_root;
  79         __le64 discard_block_size;
  80         __le64 discard_nr_blocks;
  81
  82         __le32 data_block_size;
  83         __le32 metadata_block_size;
  84         __le32 cache_blocks;
  85
  86         __le32 compat_flags;
  87         __le32 compat_ro_flags;
  88         __le32 incompat_flags;
  89
  90         __le32 read_hits;
  91         __le32 read_misses;
  92         __le32 write_hits;
  93         __le32 write_misses;
  94
  95         __le32 policy_version[CACHE_POLICY_VERSION_SIZE];
  96
  97         /*
  98          * Metadata format 2 fields.
  99          */
 100         __le64 dirty_root;
 101 } __packed;
 102
 103 struct dm_cache_metadata {
 104         refcount_t ref_count;
 105         struct list_head list;
 106
 107         unsigned version;
 108         struct block_device *bdev;
 109         struct dm_block_manager *bm;
 110         struct dm_space_map *metadata_sm;
 111         struct dm_transaction_manager *tm;
 112
 113         struct dm_array_info info;
 114         struct dm_array_info hint_info;
 115         struct dm_disk_bitset discard_info;
 116
 117         struct rw_semaphore root_lock;
 118         unsigned long flags;
 119         dm_block_t root;
 120         dm_block_t hint_root;
 121         dm_block_t discard_root;
 122
 123         sector_t discard_block_size;
 124         dm_dblock_t discard_nr_blocks;
 125
 126         sector_t data_block_size;
 127         dm_cblock_t cache_blocks;
 128         bool changed:1;
 129         bool clean_when_opened:1;
 130
 131         char policy_name[CACHE_POLICY_NAME_SIZE];
 132         unsigned policy_version[CACHE_POLICY_VERSION_SIZE];
 133         size_t policy_hint_size;
 134         struct dm_cache_statistics stats;
 135
 136         /*
 137          * Reading the space map root can fail, so we read it into this
 138          * buffer before the superblock is locked and updated.
 139          */
 140         __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
 141
 142         /*
 143          * Set if a transaction has to be aborted but the attempt to roll
 144          * back to the previous (good) transaction failed.  The only
 145          * metadata operation permissible in this state is the closing of
 146          * the device.
 147          */
 148         bool fail_io:1;
 149
 150         /*
 151          * Metadata format 2 fields.
 152          */
 153         dm_block_t dirty_root;
 154         struct dm_disk_bitset dirty_info;
 155
 156         /*
 157          * These structures are used when loading metadata.  They're too
 158          * big to put on the stack.
 159          */
 160         struct dm_array_cursor mapping_cursor;
 161         struct dm_array_cursor hint_cursor;
 162         struct dm_bitset_cursor dirty_cursor;
 163 };
 164
 165 /*-------------------------------------------------------------------
 166  * superblock validator
 167  *-----------------------------------------------------------------*/
 168
 169 #define SUPERBLOCK_CSUM_XOR 9031977
 170
 171 static void sb_prepare_for_write(struct dm_block_validator *v,
 172                                  struct dm_block *b,
 173                                  size_t sb_block_size)
 174 {
 175         struct cache_disk_superblock *disk_super = dm_block_data(b);
 176
 177         disk_super->blocknr = cpu_to_le64(dm_block_location(b));
 178         disk_super->csum = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
 179                                                       sb_block_size - sizeof(__le32),
 180                                                       SUPERBLOCK_CSUM_XOR));
 181 }
 182
 183 static int check_metadata_version(struct cache_disk_superblock *disk_super)
 184 {
 185         uint32_t metadata_version = le32_to_cpu(disk_super->version);
 186
 187         if (metadata_version < MIN_CACHE_VERSION || metadata_version > MAX_CACHE_VERSION) {
 188                 DMERR("Cache metadata version %u found, but only versions between %u and %u supported.",
 189                       metadata_version, MIN_CACHE_VERSION, MAX_CACHE_VERSION);
 190                 return -EINVAL;
 191         }
 192
 193         return 0;
 194 }
 195
 196 static int sb_check(struct dm_block_validator *v,
 197                     struct dm_block *b,
 198                     size_t sb_block_size)
 199 {
 200         struct cache_disk_superblock *disk_super = dm_block_data(b);
 201         __le32 csum_le;
 202
 203         if (dm_block_location(b) != le64_to_cpu(disk_super->blocknr)) {
 204                 DMERR("sb_check failed: blocknr %llu: wanted %llu",
 205                       le64_to_cpu(disk_super->blocknr),
 206                       (unsigned long long)dm_block_location(b));
 207                 return -ENOTBLK;
 208         }
 209
 210         if (le64_to_cpu(disk_super->magic) != CACHE_SUPERBLOCK_MAGIC) {
 211                 DMERR("sb_check failed: magic %llu: wanted %llu",
 212                       le64_to_cpu(disk_super->magic),
 213                       (unsigned long long)CACHE_SUPERBLOCK_MAGIC);
 214                 return -EILSEQ;
 215         }
 216
 217         csum_le = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
 218                                              sb_block_size - sizeof(__le32),
 219                                              SUPERBLOCK_CSUM_XOR));
 220         if (csum_le != disk_super->csum) {
 221                 DMERR("sb_check failed: csum %u: wanted %u",
 222                       le32_to_cpu(csum_le), le32_to_cpu(disk_super->csum));
 223                 return -EILSEQ;
 224         }
 225
 226         return check_metadata_version(disk_super);
 227 }
 228
 229 static struct dm_block_validator sb_validator = {
 230         .name = "superblock",
 231         .prepare_for_write = sb_prepare_for_write,
 232         .check = sb_check
 233 };
 234
 235 /*----------------------------------------------------------------*/
 236
 237 static int superblock_read_lock(struct dm_cache_metadata *cmd,
 238                                 struct dm_block **sblock)
 239 {
 240         return dm_bm_read_lock(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 241                                &sb_validator, sblock);
 242 }
 243
 244 static int superblock_lock_zero(struct dm_cache_metadata *cmd,
 245                                 struct dm_block **sblock)
 246 {
 247         return dm_bm_write_lock_zero(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 248                                      &sb_validator, sblock);
 249 }
 250
 251 static int superblock_lock(struct dm_cache_metadata *cmd,
 252                            struct dm_block **sblock)
 253 {
 254         return dm_bm_write_lock(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 255                                 &sb_validator, sblock);
 256 }
 257
 258 /*----------------------------------------------------------------*/
 259
 260 static int __superblock_all_zeroes(struct dm_block_manager *bm, bool *result)
 261 {
 262         int r;
 263         unsigned i;
 264         struct dm_block *b;
 265         __le64 *data_le, zero = cpu_to_le64(0);
 266         unsigned sb_block_size = dm_bm_block_size(bm) / sizeof(__le64);
 267
 268         /*
 269          * We can't use a validator here - it may be all zeroes.
 270          */
 271         r = dm_bm_read_lock(bm, CACHE_SUPERBLOCK_LOCATION, NULL, &b);
 272         if (r)
 273                 return r;
 274
 275         data_le = dm_block_data(b);
 276         *result = true;
 277         for (i = 0; i < sb_block_size; i++) {
 278                 if (data_le[i] != zero) {
 279                         *result = false;
 280                         break;
 281                 }
 282         }
 283
 284         dm_bm_unlock(b);
 285
 286         return 0;
 287 }
 288
 289 static void __setup_mapping_info(struct dm_cache_metadata *cmd)
 290 {
 291         struct dm_btree_value_type vt;
 292
 293         vt.context = NULL;
 294         vt.size = sizeof(__le64);
 295         vt.inc = NULL;
 296         vt.dec = NULL;
 297         vt.equal = NULL;
 298         dm_array_info_init(&cmd->info, cmd->tm, &vt);
 299
 300         if (cmd->policy_hint_size) {
 301                 vt.size = sizeof(__le32);
 302                 dm_array_info_init(&cmd->hint_info, cmd->tm, &vt);
 303         }
 304 }
 305
 306 static int __save_sm_root(struct dm_cache_metadata *cmd)
 307 {
 308         int r;
 309         size_t metadata_len;
 310
 311         r = dm_sm_root_size(cmd->metadata_sm, &metadata_len);
 312         if (r < 0)
 313                 return r;
 314
 315         return dm_sm_copy_root(cmd->metadata_sm, &cmd->metadata_space_map_root,
 316                                metadata_len);
 317 }
 318
 319 static void __copy_sm_root(struct dm_cache_metadata *cmd,
 320                            struct cache_disk_superblock *disk_super)
 321 {
 322         memcpy(&disk_super->metadata_space_map_root,
 323                &cmd->metadata_space_map_root,
 324                sizeof(cmd->metadata_space_map_root));
 325 }
 326
 327 static bool separate_dirty_bits(struct dm_cache_metadata *cmd)
 328 {
 329         return cmd->version >= 2;
 330 }
 331
 332 static int __write_initial_superblock(struct dm_cache_metadata *cmd)
 333 {
 334         int r;
 335         struct dm_block *sblock;
 336         struct cache_disk_superblock *disk_super;
 337         sector_t bdev_size = bdev_nr_sectors(cmd->bdev);
 338
 339         /* FIXME: see if we can lose the max sectors limit */
 340         if (bdev_size > DM_CACHE_METADATA_MAX_SECTORS)
 341                 bdev_size = DM_CACHE_METADATA_MAX_SECTORS;
 342
 343         r = dm_tm_pre_commit(cmd->tm);
 344         if (r < 0)
 345                 return r;
 346
 347         /*
 348          * dm_sm_copy_root() can fail.  So we need to do it before we start
 349          * updating the superblock.
 350          */
 351         r = __save_sm_root(cmd);
 352         if (r)
 353                 return r;
 354
 355         r = superblock_lock_zero(cmd, &sblock);
 356         if (r)
 357                 return r;
 358
 359         disk_super = dm_block_data(sblock);
 360         disk_super->flags = 0;
 361         memset(disk_super->uuid, 0, sizeof(disk_super->uuid));
 362         disk_super->magic = cpu_to_le64(CACHE_SUPERBLOCK_MAGIC);
 363         disk_super->version = cpu_to_le32(cmd->version);
 364         memset(disk_super->policy_name, 0, sizeof(disk_super->policy_name));
 365         memset(disk_super->policy_version, 0, sizeof(disk_super->policy_version));
 366         disk_super->policy_hint_size = cpu_to_le32(0);
 367
 368         __copy_sm_root(cmd, disk_super);
 369
 370         disk_super->mapping_root = cpu_to_le64(cmd->root);
 371         disk_super->hint_root = cpu_to_le64(cmd->hint_root);
 372         disk_super->discard_root = cpu_to_le64(cmd->discard_root);
 373         disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size);
 374         disk_super->discard_nr_blocks = cpu_to_le64(from_dblock(cmd->discard_nr_blocks));
 375         disk_super->metadata_block_size = cpu_to_le32(DM_CACHE_METADATA_BLOCK_SIZE);
 376         disk_super->data_block_size = cpu_to_le32(cmd->data_block_size);
 377         disk_super->cache_blocks = cpu_to_le32(0);
 378
 379         disk_super->read_hits = cpu_to_le32(0);
 380         disk_super->read_misses = cpu_to_le32(0);
 381         disk_super->write_hits = cpu_to_le32(0);
 382         disk_super->write_misses = cpu_to_le32(0);
 383
 384         if (separate_dirty_bits(cmd))
 385                 disk_super->dirty_root = cpu_to_le64(cmd->dirty_root);
 386
 387         return dm_tm_commit(cmd->tm, sblock);
 388 }
 389
 390 static int __format_metadata(struct dm_cache_metadata *cmd)
 391 {
 392         int r;
 393
 394         r = dm_tm_create_with_sm(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 395                                  &cmd->tm, &cmd->metadata_sm);
 396         if (r < 0) {
 397                 DMERR("tm_create_with_sm failed");
 398                 return r;
 399         }
 400
 401         __setup_mapping_info(cmd);
 402
 403         r = dm_array_empty(&cmd->info, &cmd->root);
 404         if (r < 0)
 405                 goto bad;
 406
 407         if (separate_dirty_bits(cmd)) {
 408                 dm_disk_bitset_init(cmd->tm, &cmd->dirty_info);
 409                 r = dm_bitset_empty(&cmd->dirty_info, &cmd->dirty_root);
 410                 if (r < 0)
 411                         goto bad;
 412         }
 413
 414         dm_disk_bitset_init(cmd->tm, &cmd->discard_info);
 415         r = dm_bitset_empty(&cmd->discard_info, &cmd->discard_root);
 416         if (r < 0)
 417                 goto bad;
 418
 419         cmd->discard_block_size = 0;
 420         cmd->discard_nr_blocks = 0;
 421
 422         r = __write_initial_superblock(cmd);
 423         if (r)
 424                 goto bad;
 425
 426         cmd->clean_when_opened = true;
 427         return 0;
 428
 429 bad:
 430         dm_tm_destroy(cmd->tm);
 431         dm_sm_destroy(cmd->metadata_sm);
 432
 433         return r;
 434 }
 435
 436 static int __check_incompat_features(struct cache_disk_superblock *disk_super,
 437                                      struct dm_cache_metadata *cmd)
 438 {
 439         uint32_t incompat_flags, features;
 440
 441         incompat_flags = le32_to_cpu(disk_super->incompat_flags);
 442         features = incompat_flags & ~DM_CACHE_FEATURE_INCOMPAT_SUPP;
 443         if (features) {
 444                 DMERR("could not access metadata due to unsupported optional features (%lx).",
 445                       (unsigned long)features);
 446                 return -EINVAL;
 447         }
 448
 449         /*
 450          * Check for read-only metadata to skip the following RDWR checks.
 451          */
 452         if (bdev_read_only(cmd->bdev))
 453                 return 0;
 454
 455         features = le32_to_cpu(disk_super->compat_ro_flags) & ~DM_CACHE_FEATURE_COMPAT_RO_SUPP;
 456         if (features) {
 457                 DMERR("could not access metadata RDWR due to unsupported optional features (%lx).",
 458                       (unsigned long)features);
 459                 return -EINVAL;
 460         }
 461
 462         return 0;
 463 }
 464
 465 static int __open_metadata(struct dm_cache_metadata *cmd)
 466 {
 467         int r;
 468         struct dm_block *sblock;
 469         struct cache_disk_superblock *disk_super;
 470         unsigned long sb_flags;
 471
 472         r = superblock_read_lock(cmd, &sblock);
 473         if (r < 0) {
 474                 DMERR("couldn't read lock superblock");
 475                 return r;
 476         }
 477
 478         disk_super = dm_block_data(sblock);
 479
 480         /* Verify the data block size hasn't changed */
 481         if (le32_to_cpu(disk_super->data_block_size) != cmd->data_block_size) {
 482                 DMERR("changing the data block size (from %u to %llu) is not supported",
 483                       le32_to_cpu(disk_super->data_block_size),
 484                       (unsigned long long)cmd->data_block_size);
 485                 r = -EINVAL;
 486                 goto bad;
 487         }
 488
 489         r = __check_incompat_features(disk_super, cmd);
 490         if (r < 0)
 491                 goto bad;
 492
 493         r = dm_tm_open_with_sm(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 494                                disk_super->metadata_space_map_root,
 495                                sizeof(disk_super->metadata_space_map_root),
 496                                &cmd->tm, &cmd->metadata_sm);
 497         if (r < 0) {
 498                 DMERR("tm_open_with_sm failed");
 499                 goto bad;
 500         }
 501
 502         __setup_mapping_info(cmd);
 503         dm_disk_bitset_init(cmd->tm, &cmd->dirty_info);
 504         dm_disk_bitset_init(cmd->tm, &cmd->discard_info);
 505         sb_flags = le32_to_cpu(disk_super->flags);
 506         cmd->clean_when_opened = test_bit(CLEAN_SHUTDOWN, &sb_flags);
 507         dm_bm_unlock(sblock);
 508
 509         return 0;
 510
 511 bad:
 512         dm_bm_unlock(sblock);
 513         return r;
 514 }
 515
 516 static int __open_or_format_metadata(struct dm_cache_metadata *cmd,
 517                                      bool format_device)
 518 {
 519         int r;
 520         bool unformatted = false;
 521
 522         r = __superblock_all_zeroes(cmd->bm, &unformatted);
 523         if (r)
 524                 return r;
 525
 526         if (unformatted)
 527                 return format_device ? __format_metadata(cmd) : -EPERM;
 528
 529         return __open_metadata(cmd);
 530 }
 531
 532 static int __create_persistent_data_objects(struct dm_cache_metadata *cmd,
 533                                             bool may_format_device)
 534 {
 535         int r;
 536         cmd->bm = dm_block_manager_create(cmd->bdev, DM_CACHE_METADATA_BLOCK_SIZE << SECTOR_SHIFT,
 537                                           CACHE_MAX_CONCURRENT_LOCKS);
 538         if (IS_ERR(cmd->bm)) {
 539                 DMERR("could not create block manager");
 540                 r = PTR_ERR(cmd->bm);
 541                 cmd->bm = NULL;
 542                 return r;
 543         }
 544
 545         r = __open_or_format_metadata(cmd, may_format_device);
 546         if (r) {
 547                 dm_block_manager_destroy(cmd->bm);
 548                 cmd->bm = NULL;
 549         }
 550
 551         return r;
 552 }
 553
 554 static void __destroy_persistent_data_objects(struct dm_cache_metadata *cmd,
 555                                               bool destroy_bm)
 556 {
 557         dm_sm_destroy(cmd->metadata_sm);
 558         dm_tm_destroy(cmd->tm);
 559         if (destroy_bm)
 560                 dm_block_manager_destroy(cmd->bm);
 561 }
 562
 563 typedef unsigned long (*flags_mutator)(unsigned long);
 564
 565 static void update_flags(struct cache_disk_superblock *disk_super,
 566                          flags_mutator mutator)
 567 {
 568         uint32_t sb_flags = mutator(le32_to_cpu(disk_super->flags));
 569         disk_super->flags = cpu_to_le32(sb_flags);
 570 }
 571
 572 static unsigned long set_clean_shutdown(unsigned long flags)
 573 {
 574         set_bit(CLEAN_SHUTDOWN, &flags);
 575         return flags;
 576 }
 577
 578 static unsigned long clear_clean_shutdown(unsigned long flags)
 579 {
 580         clear_bit(CLEAN_SHUTDOWN, &flags);
 581         return flags;
 582 }
 583
 584 static void read_superblock_fields(struct dm_cache_metadata *cmd,
 585                                    struct cache_disk_superblock *disk_super)
 586 {
 587         cmd->version = le32_to_cpu(disk_super->version);
 588         cmd->flags = le32_to_cpu(disk_super->flags);
 589         cmd->root = le64_to_cpu(disk_super->mapping_root);
 590         cmd->hint_root = le64_to_cpu(disk_super->hint_root);
 591         cmd->discard_root = le64_to_cpu(disk_super->discard_root);
 592         cmd->discard_block_size = le64_to_cpu(disk_super->discard_block_size);
 593         cmd->discard_nr_blocks = to_dblock(le64_to_cpu(disk_super->discard_nr_blocks));
 594         cmd->data_block_size = le32_to_cpu(disk_super->data_block_size);
 595         cmd->cache_blocks = to_cblock(le32_to_cpu(disk_super->cache_blocks));
 596         strncpy(cmd->policy_name, disk_super->policy_name, sizeof(cmd->policy_name));
 597         cmd->policy_version[0] = le32_to_cpu(disk_super->policy_version[0]);
 598         cmd->policy_version[1] = le32_to_cpu(disk_super->policy_version[1]);
 599         cmd->policy_version[2] = le32_to_cpu(disk_super->policy_version[2]);
 600         cmd->policy_hint_size = le32_to_cpu(disk_super->policy_hint_size);
 601
 602         cmd->stats.read_hits = le32_to_cpu(disk_super->read_hits);
 603         cmd->stats.read_misses = le32_to_cpu(disk_super->read_misses);
 604         cmd->stats.write_hits = le32_to_cpu(disk_super->write_hits);
 605         cmd->stats.write_misses = le32_to_cpu(disk_super->write_misses);
 606
 607         if (separate_dirty_bits(cmd))
 608                 cmd->dirty_root = le64_to_cpu(disk_super->dirty_root);
 609
 610         cmd->changed = false;
 611 }
 612
 613 /*
 614  * The mutator updates the superblock flags.
 615  */
 616 static int __begin_transaction_flags(struct dm_cache_metadata *cmd,
 617                                      flags_mutator mutator)
 618 {
 619         int r;
 620         struct cache_disk_superblock *disk_super;
 621         struct dm_block *sblock;
 622
 623         r = superblock_lock(cmd, &sblock);
 624         if (r)
 625                 return r;
 626
 627         disk_super = dm_block_data(sblock);
 628         update_flags(disk_super, mutator);
 629         read_superblock_fields(cmd, disk_super);
 630         dm_bm_unlock(sblock);
 631
 632         return dm_bm_flush(cmd->bm);
 633 }
 634
 635 static int __begin_transaction(struct dm_cache_metadata *cmd)
 636 {
 637         int r;
 638         struct cache_disk_superblock *disk_super;
 639         struct dm_block *sblock;
 640
 641         /*
 642          * We re-read the superblock every time.  Shouldn't need to do this
 643          * really.
 644          */
 645         r = superblock_read_lock(cmd, &sblock);
 646         if (r)
 647                 return r;
 648
 649         disk_super = dm_block_data(sblock);
 650         read_superblock_fields(cmd, disk_super);
 651         dm_bm_unlock(sblock);
 652
 653         return 0;
 654 }
 655
 656 static int __commit_transaction(struct dm_cache_metadata *cmd,
 657                                 flags_mutator mutator)
 658 {
 659         int r;
 660         struct cache_disk_superblock *disk_super;
 661         struct dm_block *sblock;
 662
 663         /*
 664          * We need to know if the cache_disk_superblock exceeds a 512-byte sector.
 665          */
 666         BUILD_BUG_ON(sizeof(struct cache_disk_superblock) > 512);
 667
 668         if (separate_dirty_bits(cmd)) {
 669                 r = dm_bitset_flush(&cmd->dirty_info, cmd->dirty_root,
 670                                     &cmd->dirty_root);
 671                 if (r)
 672                         return r;
 673         }
 674
 675         r = dm_bitset_flush(&cmd->discard_info, cmd->discard_root,
 676                             &cmd->discard_root);
 677         if (r)
 678                 return r;
 679
 680         r = dm_tm_pre_commit(cmd->tm);
 681         if (r < 0)
 682                 return r;
 683
 684         r = __save_sm_root(cmd);
 685         if (r)
 686                 return r;
 687
 688         r = superblock_lock(cmd, &sblock);
 689         if (r)
 690                 return r;
 691
 692         disk_super = dm_block_data(sblock);
 693
 694         disk_super->flags = cpu_to_le32(cmd->flags);
 695         if (mutator)
 696                 update_flags(disk_super, mutator);
 697
 698         disk_super->mapping_root = cpu_to_le64(cmd->root);
 699         if (separate_dirty_bits(cmd))
 700                 disk_super->dirty_root = cpu_to_le64(cmd->dirty_root);
 701         disk_super->hint_root = cpu_to_le64(cmd->hint_root);
 702         disk_super->discard_root = cpu_to_le64(cmd->discard_root);
 703         disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size);
 704         disk_super->discard_nr_blocks = cpu_to_le64(from_dblock(cmd->discard_nr_blocks));
 705         disk_super->cache_blocks = cpu_to_le32(from_cblock(cmd->cache_blocks));
 706         strncpy(disk_super->policy_name, cmd->policy_name, sizeof(disk_super->policy_name));
 707         disk_super->policy_version[0] = cpu_to_le32(cmd->policy_version[0]);
 708         disk_super->policy_version[1] = cpu_to_le32(cmd->policy_version[1]);
 709         disk_super->policy_version[2] = cpu_to_le32(cmd->policy_version[2]);
 710         disk_super->policy_hint_size = cpu_to_le32(cmd->policy_hint_size);
 711
 712         disk_super->read_hits = cpu_to_le32(cmd->stats.read_hits);
 713         disk_super->read_misses = cpu_to_le32(cmd->stats.read_misses);
 714         disk_super->write_hits = cpu_to_le32(cmd->stats.write_hits);
 715         disk_super->write_misses = cpu_to_le32(cmd->stats.write_misses);
 716         __copy_sm_root(cmd, disk_super);
 717
 718         return dm_tm_commit(cmd->tm, sblock);
 719 }
 720
 721 /*----------------------------------------------------------------*/
 722
 723 /*
 724  * The mappings are held in a dm-array that has 64-bit values stored in
 725  * little-endian format.  The index is the cblock, the high 48bits of the
 726  * value are the oblock and the low 16 bit the flags.
 727  */
 728 #define FLAGS_MASK ((1 << 16) - 1)
 729
 730 static __le64 pack_value(dm_oblock_t block, unsigned flags)
 731 {
 732         uint64_t value = from_oblock(block);
 733         value <<= 16;
 734         value = value | (flags & FLAGS_MASK);
 735         return cpu_to_le64(value);
 736 }
 737
 738 static void unpack_value(__le64 value_le, dm_oblock_t *block, unsigned *flags)
 739 {
 740         uint64_t value = le64_to_cpu(value_le);
 741         uint64_t b = value >> 16;
 742         *block = to_oblock(b);
 743         *flags = value & FLAGS_MASK;
 744 }
 745
 746 /*----------------------------------------------------------------*/
 747
 748 static struct dm_cache_metadata *metadata_open(struct block_device *bdev,
 749                                                sector_t data_block_size,
 750                                                bool may_format_device,
 751                                                size_t policy_hint_size,
 752                                                unsigned metadata_version)
 753 {
 754         int r;
 755         struct dm_cache_metadata *cmd;
 756
 757         cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
 758         if (!cmd) {
 759                 DMERR("could not allocate metadata struct");
 760                 return ERR_PTR(-ENOMEM);
 761         }
 762
 763         cmd->version = metadata_version;
 764         refcount_set(&cmd->ref_count, 1);
 765         init_rwsem(&cmd->root_lock);
 766         cmd->bdev = bdev;
 767         cmd->data_block_size = data_block_size;
 768         cmd->cache_blocks = 0;
 769         cmd->policy_hint_size = policy_hint_size;
 770         cmd->changed = true;
 771         cmd->fail_io = false;
 772
 773         r = __create_persistent_data_objects(cmd, may_format_device);
 774         if (r) {
 775                 kfree(cmd);
 776                 return ERR_PTR(r);
 777         }
 778
 779         r = __begin_transaction_flags(cmd, clear_clean_shutdown);
 780         if (r < 0) {
 781                 dm_cache_metadata_close(cmd);
 782                 return ERR_PTR(r);
 783         }
 784
 785         return cmd;
 786 }
 787
 788 /*
 789  * We keep a little list of ref counted metadata objects to prevent two
 790  * different target instances creating separate bufio instances.  This is
 791  * an issue if a table is reloaded before the suspend.
 792  */
 793 static DEFINE_MUTEX(table_lock);
 794 static LIST_HEAD(table);
 795
 796 static struct dm_cache_metadata *lookup(struct block_device *bdev)
 797 {
 798         struct dm_cache_metadata *cmd;
 799
 800         list_for_each_entry(cmd, &table, list)
 801                 if (cmd->bdev == bdev) {
 802                         refcount_inc(&cmd->ref_count);
 803                         return cmd;
 804                 }
 805
 806         return NULL;
 807 }
 808
 809 static struct dm_cache_metadata *lookup_or_open(struct block_device *bdev,
 810                                                 sector_t data_block_size,
 811                                                 bool may_format_device,
 812                                                 size_t policy_hint_size,
 813                                                 unsigned metadata_version)
 814 {
 815         struct dm_cache_metadata *cmd, *cmd2;
 816
 817         mutex_lock(&table_lock);
 818         cmd = lookup(bdev);
 819         mutex_unlock(&table_lock);
 820
 821         if (cmd)
 822                 return cmd;
 823
 824         cmd = metadata_open(bdev, data_block_size, may_format_device,
 825                             policy_hint_size, metadata_version);
 826         if (!IS_ERR(cmd)) {
 827                 mutex_lock(&table_lock);
 828                 cmd2 = lookup(bdev);
 829                 if (cmd2) {
 830                         mutex_unlock(&table_lock);
 831                         __destroy_persistent_data_objects(cmd, true);
 832                         kfree(cmd);
 833                         return cmd2;
 834                 }
 835                 list_add(&cmd->list, &table);
 836                 mutex_unlock(&table_lock);
 837         }
 838
 839         return cmd;
 840 }
 841
 842 static bool same_params(struct dm_cache_metadata *cmd, sector_t data_block_size)
 843 {
 844         if (cmd->data_block_size != data_block_size) {
 845                 DMERR("data_block_size (%llu) different from that in metadata (%llu)",
 846                       (unsigned long long) data_block_size,
 847                       (unsigned long long) cmd->data_block_size);
 848                 return false;
 849         }
 850
 851         return true;
 852 }
 853
 854 struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev,
 855                                                  sector_t data_block_size,
 856                                                  bool may_format_device,
 857                                                  size_t policy_hint_size,
 858                                                  unsigned metadata_version)
 859 {
 860         struct dm_cache_metadata *cmd = lookup_or_open(bdev, data_block_size, may_format_device,
 861                                                        policy_hint_size, metadata_version);
 862
 863         if (!IS_ERR(cmd) && !same_params(cmd, data_block_size)) {
 864                 dm_cache_metadata_close(cmd);
 865                 return ERR_PTR(-EINVAL);
 866         }
 867
 868         return cmd;
 869 }
 870
 871 void dm_cache_metadata_close(struct dm_cache_metadata *cmd)
 872 {
 873         if (refcount_dec_and_test(&cmd->ref_count)) {
 874                 mutex_lock(&table_lock);
 875                 list_del(&cmd->list);
 876                 mutex_unlock(&table_lock);
 877
 878                 if (!cmd->fail_io)
 879                         __destroy_persistent_data_objects(cmd, true);
 880                 kfree(cmd);
 881         }
 882 }
 883
 884 /*
 885  * Checks that the given cache block is either unmapped or clean.
 886  */
 887 static int block_clean_combined_dirty(struct dm_cache_metadata *cmd, dm_cblock_t b,
 888                                       bool *result)
 889 {
 890         int r;
 891         __le64 value;
 892         dm_oblock_t ob;
 893         unsigned flags;
 894
 895         r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(b), &value);
 896         if (r)
 897                 return r;
 898
 899         unpack_value(value, &ob, &flags);
 900         *result = !((flags & M_VALID) && (flags & M_DIRTY));
 901
 902         return 0;
 903 }
 904
 905 static int blocks_are_clean_combined_dirty(struct dm_cache_metadata *cmd,
 906                                            dm_cblock_t begin, dm_cblock_t end,
 907                                            bool *result)
 908 {
 909         int r;
 910         *result = true;
 911
 912         while (begin != end) {
 913                 r = block_clean_combined_dirty(cmd, begin, result);
 914                 if (r) {
 915                         DMERR("block_clean_combined_dirty failed");
 916                         return r;
 917                 }
 918
 919                 if (!*result) {
 920                         DMERR("cache block %llu is dirty",
 921                               (unsigned long long) from_cblock(begin));
 922                         return 0;
 923                 }
 924
 925                 begin = to_cblock(from_cblock(begin) + 1);
 926         }
 927
 928         return 0;
 929 }
 930
 931 static int blocks_are_clean_separate_dirty(struct dm_cache_metadata *cmd,
 932                                            dm_cblock_t begin, dm_cblock_t end,
 933                                            bool *result)
 934 {
 935         int r;
 936         bool dirty_flag;
 937         *result = true;
 938
 939         if (from_cblock(cmd->cache_blocks) == 0)
 940                 /* Nothing to do */
 941                 return 0;
 942
 943         r = dm_bitset_cursor_begin(&cmd->dirty_info, cmd->dirty_root,
 944                                    from_cblock(cmd->cache_blocks), &cmd->dirty_cursor);
 945         if (r) {
 946                 DMERR("%s: dm_bitset_cursor_begin for dirty failed", __func__);
 947                 return r;
 948         }
 949
 950         r = dm_bitset_cursor_skip(&cmd->dirty_cursor, from_cblock(begin));
 951         if (r) {
 952                 DMERR("%s: dm_bitset_cursor_skip for dirty failed", __func__);
 953                 dm_bitset_cursor_end(&cmd->dirty_cursor);
 954                 return r;
 955         }
 956
 957         while (begin != end) {
 958                 /*
 959                  * We assume that unmapped blocks have their dirty bit
 960                  * cleared.
 961                  */
 962                 dirty_flag = dm_bitset_cursor_get_value(&cmd->dirty_cursor);
 963                 if (dirty_flag) {
 964                         DMERR("%s: cache block %llu is dirty", __func__,
 965                               (unsigned long long) from_cblock(begin));
 966                         dm_bitset_cursor_end(&cmd->dirty_cursor);
 967                         *result = false;
 968                         return 0;
 969                 }
 970
 971                 begin = to_cblock(from_cblock(begin) + 1);
 972                 if (begin == end)
 973                         break;
 974
 975                 r = dm_bitset_cursor_next(&cmd->dirty_cursor);
 976                 if (r) {
 977                         DMERR("%s: dm_bitset_cursor_next for dirty failed", __func__);
 978                         dm_bitset_cursor_end(&cmd->dirty_cursor);
 979                         return r;
 980                 }
 981         }
 982
 983         dm_bitset_cursor_end(&cmd->dirty_cursor);
 984
 985         return 0;
 986 }
 987
 988 static int blocks_are_unmapped_or_clean(struct dm_cache_metadata *cmd,
 989                                         dm_cblock_t begin, dm_cblock_t end,
 990                                         bool *result)
 991 {
 992         if (separate_dirty_bits(cmd))
 993                 return blocks_are_clean_separate_dirty(cmd, begin, end, result);
 994         else
 995                 return blocks_are_clean_combined_dirty(cmd, begin, end, result);
 996 }
 997
 998 static bool cmd_write_lock(struct dm_cache_metadata *cmd)
 999 {
1000         down_write(&cmd->root_lock);
1001         if (cmd->fail_io || dm_bm_is_read_only(cmd->bm)) {
1002                 up_write(&cmd->root_lock);
1003                 return false;
1004         }
1005         return true;
1006 }
1007
1008 #define WRITE_LOCK(cmd)                         \
1009         do {                                    \
1010                 if (!cmd_write_lock((cmd)))     \
1011                         return -EINVAL;         \
1012         } while(0)
1013
1014 #define WRITE_LOCK_VOID(cmd)                    \
1015         do {                                    \
1016                 if (!cmd_write_lock((cmd)))     \
1017                         return;                 \
1018         } while(0)
1019
1020 #define WRITE_UNLOCK(cmd) \
1021         up_write(&(cmd)->root_lock)
1022
1023 static bool cmd_read_lock(struct dm_cache_metadata *cmd)
1024 {
1025         down_read(&cmd->root_lock);
1026         if (cmd->fail_io) {
1027                 up_read(&cmd->root_lock);
1028                 return false;
1029         }
1030         return true;
1031 }
1032
1033 #define READ_LOCK(cmd)                          \
1034         do {                                    \
1035                 if (!cmd_read_lock((cmd)))      \
1036                         return -EINVAL;         \
1037         } while(0)
1038
1039 #define READ_LOCK_VOID(cmd)                     \
1040         do {                                    \
1041                 if (!cmd_read_lock((cmd)))      \
1042                         return;                 \
1043         } while(0)
1044
1045 #define READ_UNLOCK(cmd) \
1046         up_read(&(cmd)->root_lock)
1047
1048 int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size)
1049 {
1050         int r;
1051         bool clean;
1052         __le64 null_mapping = pack_value(0, 0);
1053
1054         WRITE_LOCK(cmd);
1055         __dm_bless_for_disk(&null_mapping);
1056
1057         if (from_cblock(new_cache_size) < from_cblock(cmd->cache_blocks)) {
1058                 r = blocks_are_unmapped_or_clean(cmd, new_cache_size, cmd->cache_blocks, &clean);
1059                 if (r) {
1060                         __dm_unbless_for_disk(&null_mapping);
1061                         goto out;
1062                 }
1063
1064                 if (!clean) {
1065                         DMERR("unable to shrink cache due to dirty blocks");
1066                         r = -EINVAL;
1067                         __dm_unbless_for_disk(&null_mapping);
1068                         goto out;
1069                 }
1070         }
1071
1072         r = dm_array_resize(&cmd->info, cmd->root, from_cblock(cmd->cache_blocks),
1073                             from_cblock(new_cache_size),
1074                             &null_mapping, &cmd->root);
1075         if (r)
1076                 goto out;
1077
1078         if (separate_dirty_bits(cmd)) {
1079                 r = dm_bitset_resize(&cmd->dirty_info, cmd->dirty_root,
1080                                      from_cblock(cmd->cache_blocks), from_cblock(new_cache_size),
1081                                      false, &cmd->dirty_root);
1082                 if (r)
1083                         goto out;
1084         }
1085
1086         cmd->cache_blocks = new_cache_size;
1087         cmd->changed = true;
1088
1089 out:
1090         WRITE_UNLOCK(cmd);
1091
1092         return r;
1093 }
1094
1095 int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd,
1096                                    sector_t discard_block_size,
1097                                    dm_dblock_t new_nr_entries)
1098 {
1099         int r;
1100
1101         WRITE_LOCK(cmd);
1102         r = dm_bitset_resize(&cmd->discard_info,
1103                              cmd->discard_root,
1104                              from_dblock(cmd->discard_nr_blocks),
1105                              from_dblock(new_nr_entries),
1106                              false, &cmd->discard_root);
1107         if (!r) {
1108                 cmd->discard_block_size = discard_block_size;
1109                 cmd->discard_nr_blocks = new_nr_entries;
1110         }
1111
1112         cmd->changed = true;
1113         WRITE_UNLOCK(cmd);
1114
1115         return r;
1116 }
1117
1118 static int __set_discard(struct dm_cache_metadata *cmd, dm_dblock_t b)
1119 {
1120         return dm_bitset_set_bit(&cmd->discard_info, cmd->discard_root,
1121                                  from_dblock(b), &cmd->discard_root);
1122 }
1123
1124 static int __clear_discard(struct dm_cache_metadata *cmd, dm_dblock_t b)
1125 {
1126         return dm_bitset_clear_bit(&cmd->discard_info, cmd->discard_root,
1127                                    from_dblock(b), &cmd->discard_root);
1128 }
1129
1130 static int __discard(struct dm_cache_metadata *cmd,
1131                      dm_dblock_t dblock, bool discard)
1132 {
1133         int r;
1134
1135         r = (discard ? __set_discard : __clear_discard)(cmd, dblock);
1136         if (r)
1137                 return r;
1138
1139         cmd->changed = true;
1140         return 0;
1141 }
1142
1143 int dm_cache_set_discard(struct dm_cache_metadata *cmd,
1144                          dm_dblock_t dblock, bool discard)
1145 {
1146         int r;
1147
1148         WRITE_LOCK(cmd);
1149         r = __discard(cmd, dblock, discard);
1150         WRITE_UNLOCK(cmd);
1151
1152         return r;
1153 }
1154
1155 static int __load_discards(struct dm_cache_metadata *cmd,
1156                            load_discard_fn fn, void *context)
1157 {
1158         int r = 0;
1159         uint32_t b;
1160         struct dm_bitset_cursor c;
1161
1162         if (from_dblock(cmd->discard_nr_blocks) == 0)
1163                 /* nothing to do */
1164                 return 0;
1165
1166         if (cmd->clean_when_opened) {
1167                 r = dm_bitset_flush(&cmd->discard_info, cmd->discard_root, &cmd->discard_root);
1168                 if (r)
1169                         return r;
1170
1171                 r = dm_bitset_cursor_begin(&cmd->discard_info, cmd->discard_root,
1172                                            from_dblock(cmd->discard_nr_blocks), &c);
1173                 if (r)
1174                         return r;
1175
1176                 for (b = 0; ; b++) {
1177                         r = fn(context, cmd->discard_block_size, to_dblock(b),
1178                                dm_bitset_cursor_get_value(&c));
1179                         if (r)
1180                                 break;
1181
1182                         if (b >= (from_dblock(cmd->discard_nr_blocks) - 1))
1183                                 break;
1184
1185                         r = dm_bitset_cursor_next(&c);
1186                         if (r)
1187                                 break;
1188                 }
1189
1190                 dm_bitset_cursor_end(&c);
1191
1192         } else {
1193                 for (b = 0; b < from_dblock(cmd->discard_nr_blocks); b++) {
1194                         r = fn(context, cmd->discard_block_size, to_dblock(b), false);
1195                         if (r)
1196                                 return r;
1197                 }
1198         }
1199
1200         return r;
1201 }
1202
1203 int dm_cache_load_discards(struct dm_cache_metadata *cmd,
1204                            load_discard_fn fn, void *context)
1205 {
1206         int r;
1207
1208         READ_LOCK(cmd);
1209         r = __load_discards(cmd, fn, context);
1210         READ_UNLOCK(cmd);
1211
1212         return r;
1213 }
1214
1215 int dm_cache_size(struct dm_cache_metadata *cmd, dm_cblock_t *result)
1216 {
1217         READ_LOCK(cmd);
1218         *result = cmd->cache_blocks;
1219         READ_UNLOCK(cmd);
1220
1221         return 0;
1222 }
1223
1224 static int __remove(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
1225 {
1226         int r;
1227         __le64 value = pack_value(0, 0);
1228
1229         __dm_bless_for_disk(&value);
1230         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1231                                &value, &cmd->root);
1232         if (r)
1233                 return r;
1234
1235         cmd->changed = true;
1236         return 0;
1237 }
1238
1239 int dm_cache_remove_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
1240 {
1241         int r;
1242
1243         WRITE_LOCK(cmd);
1244         r = __remove(cmd, cblock);
1245         WRITE_UNLOCK(cmd);
1246
1247         return r;
1248 }
1249
1250 static int __insert(struct dm_cache_metadata *cmd,
1251                     dm_cblock_t cblock, dm_oblock_t oblock)
1252 {
1253         int r;
1254         __le64 value = pack_value(oblock, M_VALID);
1255         __dm_bless_for_disk(&value);
1256
1257         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1258                                &value, &cmd->root);
1259         if (r)
1260                 return r;
1261
1262         cmd->changed = true;
1263         return 0;
1264 }
1265
1266 int dm_cache_insert_mapping(struct dm_cache_metadata *cmd,
1267                             dm_cblock_t cblock, dm_oblock_t oblock)
1268 {
1269         int r;
1270
1271         WRITE_LOCK(cmd);
1272         r = __insert(cmd, cblock, oblock);
1273         WRITE_UNLOCK(cmd);
1274
1275         return r;
1276 }
1277
1278 struct thunk {
1279         load_mapping_fn fn;
1280         void *context;
1281
1282         struct dm_cache_metadata *cmd;
1283         bool respect_dirty_flags;
1284         bool hints_valid;
1285 };
1286
1287 static bool policy_unchanged(struct dm_cache_metadata *cmd,
1288                              struct dm_cache_policy *policy)
1289 {
1290         const char *policy_name = dm_cache_policy_get_name(policy);
1291         const unsigned *policy_version = dm_cache_policy_get_version(policy);
1292         size_t policy_hint_size = dm_cache_policy_get_hint_size(policy);
1293
1294         /*
1295          * Ensure policy names match.
1296          */
1297         if (strncmp(cmd->policy_name, policy_name, sizeof(cmd->policy_name)))
1298                 return false;
1299
1300         /*
1301          * Ensure policy major versions match.
1302          */
1303         if (cmd->policy_version[0] != policy_version[0])
1304                 return false;
1305
1306         /*
1307          * Ensure policy hint sizes match.
1308          */
1309         if (cmd->policy_hint_size != policy_hint_size)
1310                 return false;
1311
1312         return true;
1313 }
1314
1315 static bool hints_array_initialized(struct dm_cache_metadata *cmd)
1316 {
1317         return cmd->hint_root && cmd->policy_hint_size;
1318 }
1319
1320 static bool hints_array_available(struct dm_cache_metadata *cmd,
1321                                   struct dm_cache_policy *policy)
1322 {
1323         return cmd->clean_when_opened && policy_unchanged(cmd, policy) &&
1324                 hints_array_initialized(cmd);
1325 }
1326
1327 static int __load_mapping_v1(struct dm_cache_metadata *cmd,
1328                              uint64_t cb, bool hints_valid,
1329                              struct dm_array_cursor *mapping_cursor,
1330                              struct dm_array_cursor *hint_cursor,
1331                              load_mapping_fn fn, void *context)
1332 {
1333         int r = 0;
1334
1335         __le64 mapping;
1336         __le32 hint = 0;
1337
1338         __le64 *mapping_value_le;
1339         __le32 *hint_value_le;
1340
1341         dm_oblock_t oblock;
1342         unsigned flags;
1343         bool dirty = true;
1344
1345         dm_array_cursor_get_value(mapping_cursor, (void **) &mapping_value_le);
1346         memcpy(&mapping, mapping_value_le, sizeof(mapping));
1347         unpack_value(mapping, &oblock, &flags);
1348
1349         if (flags & M_VALID) {
1350                 if (hints_valid) {
1351                         dm_array_cursor_get_value(hint_cursor, (void **) &hint_value_le);
1352                         memcpy(&hint, hint_value_le, sizeof(hint));
1353                 }
1354                 if (cmd->clean_when_opened)
1355                         dirty = flags & M_DIRTY;
1356
1357                 r = fn(context, oblock, to_cblock(cb), dirty,
1358                        le32_to_cpu(hint), hints_valid);
1359                 if (r) {
1360                         DMERR("policy couldn't load cache block %llu",
1361                               (unsigned long long) from_cblock(to_cblock(cb)));
1362                 }
1363         }
1364
1365         return r;
1366 }
1367
1368 static int __load_mapping_v2(struct dm_cache_metadata *cmd,
1369                              uint64_t cb, bool hints_valid,
1370                              struct dm_array_cursor *mapping_cursor,
1371                              struct dm_array_cursor *hint_cursor,
1372                              struct dm_bitset_cursor *dirty_cursor,
1373                              load_mapping_fn fn, void *context)
1374 {
1375         int r = 0;
1376
1377         __le64 mapping;
1378         __le32 hint = 0;
1379
1380         __le64 *mapping_value_le;
1381         __le32 *hint_value_le;
1382
1383         dm_oblock_t oblock;
1384         unsigned flags;
1385         bool dirty = true;
1386
1387         dm_array_cursor_get_value(mapping_cursor, (void **) &mapping_value_le);
1388         memcpy(&mapping, mapping_value_le, sizeof(mapping));
1389         unpack_value(mapping, &oblock, &flags);
1390
1391         if (flags & M_VALID) {
1392                 if (hints_valid) {
1393                         dm_array_cursor_get_value(hint_cursor, (void **) &hint_value_le);
1394                         memcpy(&hint, hint_value_le, sizeof(hint));
1395                 }
1396                 if (cmd->clean_when_opened)
1397                         dirty = dm_bitset_cursor_get_value(dirty_cursor);
1398
1399                 r = fn(context, oblock, to_cblock(cb), dirty,
1400                        le32_to_cpu(hint), hints_valid);
1401                 if (r) {
1402                         DMERR("policy couldn't load cache block %llu",
1403                               (unsigned long long) from_cblock(to_cblock(cb)));
1404                 }
1405         }
1406
1407         return r;
1408 }
1409
1410 static int __load_mappings(struct dm_cache_metadata *cmd,
1411                            struct dm_cache_policy *policy,
1412                            load_mapping_fn fn, void *context)
1413 {
1414         int r;
1415         uint64_t cb;
1416
1417         bool hints_valid = hints_array_available(cmd, policy);
1418
1419         if (from_cblock(cmd->cache_blocks) == 0)
1420                 /* Nothing to do */
1421                 return 0;
1422
1423         r = dm_array_cursor_begin(&cmd->info, cmd->root, &cmd->mapping_cursor);
1424         if (r)
1425                 return r;
1426
1427         if (hints_valid) {
1428                 r = dm_array_cursor_begin(&cmd->hint_info, cmd->hint_root, &cmd->hint_cursor);
1429                 if (r) {
1430                         dm_array_cursor_end(&cmd->mapping_cursor);
1431                         return r;
1432                 }
1433         }
1434
1435         if (separate_dirty_bits(cmd)) {
1436                 r = dm_bitset_cursor_begin(&cmd->dirty_info, cmd->dirty_root,
1437                                            from_cblock(cmd->cache_blocks),
1438                                            &cmd->dirty_cursor);
1439                 if (r) {
1440                         dm_array_cursor_end(&cmd->hint_cursor);
1441                         dm_array_cursor_end(&cmd->mapping_cursor);
1442                         return r;
1443                 }
1444         }
1445
1446         for (cb = 0; ; cb++) {
1447                 if (separate_dirty_bits(cmd))
1448                         r = __load_mapping_v2(cmd, cb, hints_valid,
1449                                               &cmd->mapping_cursor,
1450                                               &cmd->hint_cursor,
1451                                               &cmd->dirty_cursor,
1452                                               fn, context);
1453                 else
1454                         r = __load_mapping_v1(cmd, cb, hints_valid,
1455                                               &cmd->mapping_cursor, &cmd->hint_cursor,
1456                                               fn, context);
1457                 if (r)
1458                         goto out;
1459
1460                 /*
1461                  * We need to break out before we move the cursors.
1462                  */
1463                 if (cb >= (from_cblock(cmd->cache_blocks) - 1))
1464                         break;
1465
1466                 r = dm_array_cursor_next(&cmd->mapping_cursor);
1467                 if (r) {
1468                         DMERR("dm_array_cursor_next for mapping failed");
1469                         goto out;
1470                 }
1471
1472                 if (hints_valid) {
1473                         r = dm_array_cursor_next(&cmd->hint_cursor);
1474                         if (r) {
1475                                 dm_array_cursor_end(&cmd->hint_cursor);
1476                                 hints_valid = false;
1477                         }
1478                 }
1479
1480                 if (separate_dirty_bits(cmd)) {
1481                         r = dm_bitset_cursor_next(&cmd->dirty_cursor);
1482                         if (r) {
1483                                 DMERR("dm_bitset_cursor_next for dirty failed");
1484                                 goto out;
1485                         }
1486                 }
1487         }
1488 out:
1489         dm_array_cursor_end(&cmd->mapping_cursor);
1490         if (hints_valid)
1491                 dm_array_cursor_end(&cmd->hint_cursor);
1492
1493         if (separate_dirty_bits(cmd))
1494                 dm_bitset_cursor_end(&cmd->dirty_cursor);
1495
1496         return r;
1497 }
1498
1499 int dm_cache_load_mappings(struct dm_cache_metadata *cmd,
1500                            struct dm_cache_policy *policy,
1501                            load_mapping_fn fn, void *context)
1502 {
1503         int r;
1504
1505         READ_LOCK(cmd);
1506         r = __load_mappings(cmd, policy, fn, context);
1507         READ_UNLOCK(cmd);
1508
1509         return r;
1510 }
1511
1512 static int __dump_mapping(void *context, uint64_t cblock, void *leaf)
1513 {
1514         __le64 value;
1515         dm_oblock_t oblock;
1516         unsigned flags;
1517
1518         memcpy(&value, leaf, sizeof(value));
1519         unpack_value(value, &oblock, &flags);
1520
1521         return 0;
1522 }
1523
1524 static int __dump_mappings(struct dm_cache_metadata *cmd)
1525 {
1526         return dm_array_walk(&cmd->info, cmd->root, __dump_mapping, NULL);
1527 }
1528
1529 void dm_cache_dump(struct dm_cache_metadata *cmd)
1530 {
1531         READ_LOCK_VOID(cmd);
1532         __dump_mappings(cmd);
1533         READ_UNLOCK(cmd);
1534 }
1535
1536 int dm_cache_changed_this_transaction(struct dm_cache_metadata *cmd)
1537 {
1538         int r;
1539
1540         READ_LOCK(cmd);
1541         r = cmd->changed;
1542         READ_UNLOCK(cmd);
1543
1544         return r;
1545 }
1546
1547 static int __dirty(struct dm_cache_metadata *cmd, dm_cblock_t cblock, bool dirty)
1548 {
1549         int r;
1550         unsigned flags;
1551         dm_oblock_t oblock;
1552         __le64 value;
1553
1554         r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(cblock), &value);
1555         if (r)
1556                 return r;
1557
1558         unpack_value(value, &oblock, &flags);
1559
1560         if (((flags & M_DIRTY) && dirty) || (!(flags & M_DIRTY) && !dirty))
1561                 /* nothing to be done */
1562                 return 0;
1563
1564         value = pack_value(oblock, (flags & ~M_DIRTY) | (dirty ? M_DIRTY : 0));
1565         __dm_bless_for_disk(&value);
1566
1567         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1568                                &value, &cmd->root);
1569         if (r)
1570                 return r;
1571
1572         cmd->changed = true;
1573         return 0;
1574
1575 }
1576
1577 static int __set_dirty_bits_v1(struct dm_cache_metadata *cmd, unsigned nr_bits, unsigned long *bits)
1578 {
1579         int r;
1580         unsigned i;
1581         for (i = 0; i < nr_bits; i++) {
1582                 r = __dirty(cmd, to_cblock(i), test_bit(i, bits));
1583                 if (r)
1584                         return r;
1585         }
1586
1587         return 0;
1588 }
1589
1590 static int is_dirty_callback(uint32_t index, bool *value, void *context)
1591 {
1592         unsigned long *bits = context;
1593         *value = test_bit(index, bits);
1594         return 0;
1595 }
1596
1597 static int __set_dirty_bits_v2(struct dm_cache_metadata *cmd, unsigned nr_bits, unsigned long *bits)
1598 {
1599         int r = 0;
1600
1601         /* nr_bits is really just a sanity check */
1602         if (nr_bits != from_cblock(cmd->cache_blocks)) {
1603                 DMERR("dirty bitset is wrong size");
1604                 return -EINVAL;
1605         }
1606
1607         r = dm_bitset_del(&cmd->dirty_info, cmd->dirty_root);
1608         if (r)
1609                 return r;
1610
1611         cmd->changed = true;
1612         return dm_bitset_new(&cmd->dirty_info, &cmd->dirty_root, nr_bits, is_dirty_callback, bits);
1613 }
1614
1615 int dm_cache_set_dirty_bits(struct dm_cache_metadata *cmd,
1616                             unsigned nr_bits,
1617                             unsigned long *bits)
1618 {
1619         int r;
1620
1621         WRITE_LOCK(cmd);
1622         if (separate_dirty_bits(cmd))
1623                 r = __set_dirty_bits_v2(cmd, nr_bits, bits);
1624         else
1625                 r = __set_dirty_bits_v1(cmd, nr_bits, bits);
1626         WRITE_UNLOCK(cmd);
1627
1628         return r;
1629 }
1630
1631 void dm_cache_metadata_get_stats(struct dm_cache_metadata *cmd,
1632                                  struct dm_cache_statistics *stats)
1633 {
1634         READ_LOCK_VOID(cmd);
1635         *stats = cmd->stats;
1636         READ_UNLOCK(cmd);
1637 }
1638
1639 void dm_cache_metadata_set_stats(struct dm_cache_metadata *cmd,
1640                                  struct dm_cache_statistics *stats)
1641 {
1642         WRITE_LOCK_VOID(cmd);
1643         cmd->stats = *stats;
1644         WRITE_UNLOCK(cmd);
1645 }
1646
1647 int dm_cache_commit(struct dm_cache_metadata *cmd, bool clean_shutdown)
1648 {
1649         int r = -EINVAL;
1650         flags_mutator mutator = (clean_shutdown ? set_clean_shutdown :
1651                                  clear_clean_shutdown);
1652
1653         WRITE_LOCK(cmd);
1654         if (cmd->fail_io)
1655                 goto out;
1656
1657         r = __commit_transaction(cmd, mutator);
1658         if (r)
1659                 goto out;
1660
1661         r = __begin_transaction(cmd);
1662 out:
1663         WRITE_UNLOCK(cmd);
1664         return r;
1665 }
1666
1667 int dm_cache_get_free_metadata_block_count(struct dm_cache_metadata *cmd,
1668                                            dm_block_t *result)
1669 {
1670         int r = -EINVAL;
1671
1672         READ_LOCK(cmd);
1673         if (!cmd->fail_io)
1674                 r = dm_sm_get_nr_free(cmd->metadata_sm, result);
1675         READ_UNLOCK(cmd);
1676
1677         return r;
1678 }
1679
1680 int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd,
1681                                    dm_block_t *result)
1682 {
1683         int r = -EINVAL;
1684
1685         READ_LOCK(cmd);
1686         if (!cmd->fail_io)
1687                 r = dm_sm_get_nr_blocks(cmd->metadata_sm, result);
1688         READ_UNLOCK(cmd);
1689
1690         return r;
1691 }
1692
1693 /*----------------------------------------------------------------*/
1694
1695 static int get_hint(uint32_t index, void *value_le, void *context)
1696 {
1697         uint32_t value;
1698         struct dm_cache_policy *policy = context;
1699
1700         value = policy_get_hint(policy, to_cblock(index));
1701         *((__le32 *) value_le) = cpu_to_le32(value);
1702
1703         return 0;
1704 }
1705
1706 /*
1707  * It's quicker to always delete the hint array, and recreate with
1708  * dm_array_new().
1709  */
1710 static int write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1711 {
1712         int r;
1713         size_t hint_size;
1714         const char *policy_name = dm_cache_policy_get_name(policy);
1715         const unsigned *policy_version = dm_cache_policy_get_version(policy);
1716
1717         if (!policy_name[0] ||
1718             (strlen(policy_name) > sizeof(cmd->policy_name) - 1))
1719                 return -EINVAL;
1720
1721         strncpy(cmd->policy_name, policy_name, sizeof(cmd->policy_name));
1722         memcpy(cmd->policy_version, policy_version, sizeof(cmd->policy_version));
1723
1724         hint_size = dm_cache_policy_get_hint_size(policy);
1725         if (!hint_size)
1726                 return 0; /* short-circuit hints initialization */
1727         cmd->policy_hint_size = hint_size;
1728
1729         if (cmd->hint_root) {
1730                 r = dm_array_del(&cmd->hint_info, cmd->hint_root);
1731                 if (r)
1732                         return r;
1733         }
1734
1735         return dm_array_new(&cmd->hint_info, &cmd->hint_root,
1736                             from_cblock(cmd->cache_blocks),
1737                             get_hint, policy);
1738 }
1739
1740 int dm_cache_write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1741 {
1742         int r;
1743
1744         WRITE_LOCK(cmd);
1745         r = write_hints(cmd, policy);
1746         WRITE_UNLOCK(cmd);
1747
1748         return r;
1749 }
1750
1751 int dm_cache_metadata_all_clean(struct dm_cache_metadata *cmd, bool *result)
1752 {
1753         int r;
1754
1755         READ_LOCK(cmd);
1756         r = blocks_are_unmapped_or_clean(cmd, 0, cmd->cache_blocks, result);
1757         READ_UNLOCK(cmd);
1758
1759         return r;
1760 }
1761
1762 void dm_cache_metadata_set_read_only(struct dm_cache_metadata *cmd)
1763 {
1764         WRITE_LOCK_VOID(cmd);
1765         dm_bm_set_read_only(cmd->bm);
1766         WRITE_UNLOCK(cmd);
1767 }
1768
1769 void dm_cache_metadata_set_read_write(struct dm_cache_metadata *cmd)
1770 {
1771         WRITE_LOCK_VOID(cmd);
1772         dm_bm_set_read_write(cmd->bm);
1773         WRITE_UNLOCK(cmd);
1774 }
1775
1776 int dm_cache_metadata_set_needs_check(struct dm_cache_metadata *cmd)
1777 {
1778         int r;
1779         struct dm_block *sblock;
1780         struct cache_disk_superblock *disk_super;
1781
1782         WRITE_LOCK(cmd);
1783         set_bit(NEEDS_CHECK, &cmd->flags);
1784
1785         r = superblock_lock(cmd, &sblock);
1786         if (r) {
1787                 DMERR("couldn't read superblock");
1788                 goto out;
1789         }
1790
1791         disk_super = dm_block_data(sblock);
1792         disk_super->flags = cpu_to_le32(cmd->flags);
1793
1794         dm_bm_unlock(sblock);
1795
1796 out:
1797         WRITE_UNLOCK(cmd);
1798         return r;
1799 }
1800
1801 int dm_cache_metadata_needs_check(struct dm_cache_metadata *cmd, bool *result)
1802 {
1803         READ_LOCK(cmd);
1804         *result = !!test_bit(NEEDS_CHECK, &cmd->flags);
1805         READ_UNLOCK(cmd);
1806
1807         return 0;
1808 }
1809
1810 int dm_cache_metadata_abort(struct dm_cache_metadata *cmd)
1811 {
1812         int r = -EINVAL;
1813         struct dm_block_manager *old_bm = NULL, *new_bm = NULL;
1814
1815         /* fail_io is double-checked with cmd->root_lock held below */
1816         if (unlikely(cmd->fail_io))
1817                 return r;
1818
1819         /*
1820          * Replacement block manager (new_bm) is created and old_bm destroyed outside of
1821          * cmd root_lock to avoid ABBA deadlock that would result (due to life-cycle of
1822          * shrinker associated with the block manager's bufio client vs cmd root_lock).
1823          * - must take shrinker_rwsem without holding cmd->root_lock
1824          */
1825         new_bm = dm_block_manager_create(cmd->bdev, DM_CACHE_METADATA_BLOCK_SIZE << SECTOR_SHIFT,
1826                                          CACHE_MAX_CONCURRENT_LOCKS);
1827
1828         WRITE_LOCK(cmd);
1829         if (cmd->fail_io) {
1830                 WRITE_UNLOCK(cmd);
1831                 goto out;
1832         }
1833
1834         __destroy_persistent_data_objects(cmd, false);
1835         old_bm = cmd->bm;
1836         if (IS_ERR(new_bm)) {
1837                 DMERR("could not create block manager during abort");
1838                 cmd->bm = NULL;
1839                 r = PTR_ERR(new_bm);
1840                 goto out_unlock;
1841         }
1842
1843         cmd->bm = new_bm;
1844         r = __open_or_format_metadata(cmd, false);
1845         if (r) {
1846                 cmd->bm = NULL;
1847                 goto out_unlock;
1848         }
1849         new_bm = NULL;
1850 out_unlock:
1851         if (r)
1852                 cmd->fail_io = true;
1853         WRITE_UNLOCK(cmd);
1854         dm_block_manager_destroy(old_bm);
1855 out:
1856         if (new_bm && !IS_ERR(new_bm))
1857                 dm_block_manager_destroy(new_bm);
1858
1859         return r;
1860 }