drivers/md/dm-cache-metadata.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2012 Red Hat, Inc.
   4  *
   5  * This file is released under the GPL.
   6  */
   7
   8 #include "dm-cache-metadata.h"
   9
  10 #include "persistent-data/dm-array.h"
  11 #include "persistent-data/dm-bitset.h"
  12 #include "persistent-data/dm-space-map.h"
  13 #include "persistent-data/dm-space-map-disk.h"
  14 #include "persistent-data/dm-transaction-manager.h"
  15
  16 #include <linux/device-mapper.h>
  17 #include <linux/refcount.h>
  18
  19 /*----------------------------------------------------------------*/
  20
  21 #define DM_MSG_PREFIX   "cache metadata"
  22
  23 #define CACHE_SUPERBLOCK_MAGIC 06142003
  24 #define CACHE_SUPERBLOCK_LOCATION 0
  25
  26 /*
  27  * defines a range of metadata versions that this module can handle.
  28  */
  29 #define MIN_CACHE_VERSION 1
  30 #define MAX_CACHE_VERSION 2
  31
  32 /*
  33  *  3 for btree insert +
  34  *  2 for btree lookup used within space map
  35  */
  36 #define CACHE_MAX_CONCURRENT_LOCKS 5
  37 #define SPACE_MAP_ROOT_SIZE 128
  38
  39 enum superblock_flag_bits {
  40         /* for spotting crashes that would invalidate the dirty bitset */
  41         CLEAN_SHUTDOWN,
  42         /* metadata must be checked using the tools */
  43         NEEDS_CHECK,
  44 };
  45
  46 /*
  47  * Each mapping from cache block -> origin block carries a set of flags.
  48  */
  49 enum mapping_bits {
  50         /*
  51          * A valid mapping.  Because we're using an array we clear this
  52          * flag for an non existant mapping.
  53          */
  54         M_VALID = 1,
  55
  56         /*
  57          * The data on the cache is different from that on the origin.
  58          * This flag is only used by metadata format 1.
  59          */
  60         M_DIRTY = 2
  61 };
  62
  63 struct cache_disk_superblock {
  64         __le32 csum;
  65         __le32 flags;
  66         __le64 blocknr;
  67
  68         __u8 uuid[16];
  69         __le64 magic;
  70         __le32 version;
  71
  72         __u8 policy_name[CACHE_POLICY_NAME_SIZE];
  73         __le32 policy_hint_size;
  74
  75         __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
  76         __le64 mapping_root;
  77         __le64 hint_root;
  78
  79         __le64 discard_root;
  80         __le64 discard_block_size;
  81         __le64 discard_nr_blocks;
  82
  83         __le32 data_block_size;
  84         __le32 metadata_block_size;
  85         __le32 cache_blocks;
  86
  87         __le32 compat_flags;
  88         __le32 compat_ro_flags;
  89         __le32 incompat_flags;
  90
  91         __le32 read_hits;
  92         __le32 read_misses;
  93         __le32 write_hits;
  94         __le32 write_misses;
  95
  96         __le32 policy_version[CACHE_POLICY_VERSION_SIZE];
  97
  98         /*
  99          * Metadata format 2 fields.
 100          */
 101         __le64 dirty_root;
 102 } __packed;
 103
 104 struct dm_cache_metadata {
 105         refcount_t ref_count;
 106         struct list_head list;
 107
 108         unsigned int version;
 109         struct block_device *bdev;
 110         struct dm_block_manager *bm;
 111         struct dm_space_map *metadata_sm;
 112         struct dm_transaction_manager *tm;
 113
 114         struct dm_array_info info;
 115         struct dm_array_info hint_info;
 116         struct dm_disk_bitset discard_info;
 117
 118         struct rw_semaphore root_lock;
 119         unsigned long flags;
 120         dm_block_t root;
 121         dm_block_t hint_root;
 122         dm_block_t discard_root;
 123
 124         sector_t discard_block_size;
 125         dm_dblock_t discard_nr_blocks;
 126
 127         sector_t data_block_size;
 128         dm_cblock_t cache_blocks;
 129         bool changed:1;
 130         bool clean_when_opened:1;
 131
 132         char policy_name[CACHE_POLICY_NAME_SIZE];
 133         unsigned int policy_version[CACHE_POLICY_VERSION_SIZE];
 134         size_t policy_hint_size;
 135         struct dm_cache_statistics stats;
 136
 137         /*
 138          * Reading the space map root can fail, so we read it into this
 139          * buffer before the superblock is locked and updated.
 140          */
 141         __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
 142
 143         /*
 144          * Set if a transaction has to be aborted but the attempt to roll
 145          * back to the previous (good) transaction failed.  The only
 146          * metadata operation permissible in this state is the closing of
 147          * the device.
 148          */
 149         bool fail_io:1;
 150
 151         /*
 152          * Metadata format 2 fields.
 153          */
 154         dm_block_t dirty_root;
 155         struct dm_disk_bitset dirty_info;
 156
 157         /*
 158          * These structures are used when loading metadata.  They're too
 159          * big to put on the stack.
 160          */
 161         struct dm_array_cursor mapping_cursor;
 162         struct dm_array_cursor hint_cursor;
 163         struct dm_bitset_cursor dirty_cursor;
 164 };
 165
 166 /*
 167  *-----------------------------------------------------------------
 168  * superblock validator
 169  *-----------------------------------------------------------------
 170  */
 171 #define SUPERBLOCK_CSUM_XOR 9031977
 172
 173 static void sb_prepare_for_write(const struct dm_block_validator *v,
 174                                  struct dm_block *b,
 175                                  size_t sb_block_size)
 176 {
 177         struct cache_disk_superblock *disk_super = dm_block_data(b);
 178
 179         disk_super->blocknr = cpu_to_le64(dm_block_location(b));
 180         disk_super->csum = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
 181                                                       sb_block_size - sizeof(__le32),
 182                                                       SUPERBLOCK_CSUM_XOR));
 183 }
 184
 185 static int check_metadata_version(struct cache_disk_superblock *disk_super)
 186 {
 187         uint32_t metadata_version = le32_to_cpu(disk_super->version);
 188
 189         if (metadata_version < MIN_CACHE_VERSION || metadata_version > MAX_CACHE_VERSION) {
 190                 DMERR("Cache metadata version %u found, but only versions between %u and %u supported.",
 191                       metadata_version, MIN_CACHE_VERSION, MAX_CACHE_VERSION);
 192                 return -EINVAL;
 193         }
 194
 195         return 0;
 196 }
 197
 198 static int sb_check(const struct dm_block_validator *v,
 199                     struct dm_block *b,
 200                     size_t sb_block_size)
 201 {
 202         struct cache_disk_superblock *disk_super = dm_block_data(b);
 203         __le32 csum_le;
 204
 205         if (dm_block_location(b) != le64_to_cpu(disk_super->blocknr)) {
 206                 DMERR("%s failed: blocknr %llu: wanted %llu",
 207                       __func__, le64_to_cpu(disk_super->blocknr),
 208                       (unsigned long long)dm_block_location(b));
 209                 return -ENOTBLK;
 210         }
 211
 212         if (le64_to_cpu(disk_super->magic) != CACHE_SUPERBLOCK_MAGIC) {
 213                 DMERR("%s failed: magic %llu: wanted %llu",
 214                       __func__, le64_to_cpu(disk_super->magic),
 215                       (unsigned long long)CACHE_SUPERBLOCK_MAGIC);
 216                 return -EILSEQ;
 217         }
 218
 219         csum_le = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
 220                                              sb_block_size - sizeof(__le32),
 221                                              SUPERBLOCK_CSUM_XOR));
 222         if (csum_le != disk_super->csum) {
 223                 DMERR("%s failed: csum %u: wanted %u",
 224                       __func__, le32_to_cpu(csum_le), le32_to_cpu(disk_super->csum));
 225                 return -EILSEQ;
 226         }
 227
 228         return check_metadata_version(disk_super);
 229 }
 230
 231 static const struct dm_block_validator sb_validator = {
 232         .name = "superblock",
 233         .prepare_for_write = sb_prepare_for_write,
 234         .check = sb_check
 235 };
 236
 237 /*----------------------------------------------------------------*/
 238
 239 static int superblock_read_lock(struct dm_cache_metadata *cmd,
 240                                 struct dm_block **sblock)
 241 {
 242         return dm_bm_read_lock(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 243                                &sb_validator, sblock);
 244 }
 245
 246 static int superblock_lock_zero(struct dm_cache_metadata *cmd,
 247                                 struct dm_block **sblock)
 248 {
 249         return dm_bm_write_lock_zero(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 250                                      &sb_validator, sblock);
 251 }
 252
 253 static int superblock_lock(struct dm_cache_metadata *cmd,
 254                            struct dm_block **sblock)
 255 {
 256         return dm_bm_write_lock(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 257                                 &sb_validator, sblock);
 258 }
 259
 260 /*----------------------------------------------------------------*/
 261
 262 static int __superblock_all_zeroes(struct dm_block_manager *bm, bool *result)
 263 {
 264         int r;
 265         unsigned int i;
 266         struct dm_block *b;
 267         __le64 *data_le, zero = cpu_to_le64(0);
 268         unsigned int sb_block_size = dm_bm_block_size(bm) / sizeof(__le64);
 269
 270         /*
 271          * We can't use a validator here - it may be all zeroes.
 272          */
 273         r = dm_bm_read_lock(bm, CACHE_SUPERBLOCK_LOCATION, NULL, &b);
 274         if (r)
 275                 return r;
 276
 277         data_le = dm_block_data(b);
 278         *result = true;
 279         for (i = 0; i < sb_block_size; i++) {
 280                 if (data_le[i] != zero) {
 281                         *result = false;
 282                         break;
 283                 }
 284         }
 285
 286         dm_bm_unlock(b);
 287
 288         return 0;
 289 }
 290
 291 static void __setup_mapping_info(struct dm_cache_metadata *cmd)
 292 {
 293         struct dm_btree_value_type vt;
 294
 295         vt.context = NULL;
 296         vt.size = sizeof(__le64);
 297         vt.inc = NULL;
 298         vt.dec = NULL;
 299         vt.equal = NULL;
 300         dm_array_info_init(&cmd->info, cmd->tm, &vt);
 301
 302         if (cmd->policy_hint_size) {
 303                 vt.size = sizeof(__le32);
 304                 dm_array_info_init(&cmd->hint_info, cmd->tm, &vt);
 305         }
 306 }
 307
 308 static int __save_sm_root(struct dm_cache_metadata *cmd)
 309 {
 310         int r;
 311         size_t metadata_len;
 312
 313         r = dm_sm_root_size(cmd->metadata_sm, &metadata_len);
 314         if (r < 0)
 315                 return r;
 316
 317         return dm_sm_copy_root(cmd->metadata_sm, &cmd->metadata_space_map_root,
 318                                metadata_len);
 319 }
 320
 321 static void __copy_sm_root(struct dm_cache_metadata *cmd,
 322                            struct cache_disk_superblock *disk_super)
 323 {
 324         memcpy(&disk_super->metadata_space_map_root,
 325                &cmd->metadata_space_map_root,
 326                sizeof(cmd->metadata_space_map_root));
 327 }
 328
 329 static bool separate_dirty_bits(struct dm_cache_metadata *cmd)
 330 {
 331         return cmd->version >= 2;
 332 }
 333
 334 static int __write_initial_superblock(struct dm_cache_metadata *cmd)
 335 {
 336         int r;
 337         struct dm_block *sblock;
 338         struct cache_disk_superblock *disk_super;
 339         sector_t bdev_size = bdev_nr_sectors(cmd->bdev);
 340
 341         /* FIXME: see if we can lose the max sectors limit */
 342         if (bdev_size > DM_CACHE_METADATA_MAX_SECTORS)
 343                 bdev_size = DM_CACHE_METADATA_MAX_SECTORS;
 344
 345         r = dm_tm_pre_commit(cmd->tm);
 346         if (r < 0)
 347                 return r;
 348
 349         /*
 350          * dm_sm_copy_root() can fail.  So we need to do it before we start
 351          * updating the superblock.
 352          */
 353         r = __save_sm_root(cmd);
 354         if (r)
 355                 return r;
 356
 357         r = superblock_lock_zero(cmd, &sblock);
 358         if (r)
 359                 return r;
 360
 361         disk_super = dm_block_data(sblock);
 362         disk_super->flags = 0;
 363         memset(disk_super->uuid, 0, sizeof(disk_super->uuid));
 364         disk_super->magic = cpu_to_le64(CACHE_SUPERBLOCK_MAGIC);
 365         disk_super->version = cpu_to_le32(cmd->version);
 366         memset(disk_super->policy_name, 0, sizeof(disk_super->policy_name));
 367         memset(disk_super->policy_version, 0, sizeof(disk_super->policy_version));
 368         disk_super->policy_hint_size = cpu_to_le32(0);
 369
 370         __copy_sm_root(cmd, disk_super);
 371
 372         disk_super->mapping_root = cpu_to_le64(cmd->root);
 373         disk_super->hint_root = cpu_to_le64(cmd->hint_root);
 374         disk_super->discard_root = cpu_to_le64(cmd->discard_root);
 375         disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size);
 376         disk_super->discard_nr_blocks = cpu_to_le64(from_dblock(cmd->discard_nr_blocks));
 377         disk_super->metadata_block_size = cpu_to_le32(DM_CACHE_METADATA_BLOCK_SIZE);
 378         disk_super->data_block_size = cpu_to_le32(cmd->data_block_size);
 379         disk_super->cache_blocks = cpu_to_le32(0);
 380
 381         disk_super->read_hits = cpu_to_le32(0);
 382         disk_super->read_misses = cpu_to_le32(0);
 383         disk_super->write_hits = cpu_to_le32(0);
 384         disk_super->write_misses = cpu_to_le32(0);
 385
 386         if (separate_dirty_bits(cmd))
 387                 disk_super->dirty_root = cpu_to_le64(cmd->dirty_root);
 388
 389         return dm_tm_commit(cmd->tm, sblock);
 390 }
 391
 392 static int __format_metadata(struct dm_cache_metadata *cmd)
 393 {
 394         int r;
 395
 396         r = dm_tm_create_with_sm(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 397                                  &cmd->tm, &cmd->metadata_sm);
 398         if (r < 0) {
 399                 DMERR("tm_create_with_sm failed");
 400                 return r;
 401         }
 402
 403         __setup_mapping_info(cmd);
 404
 405         r = dm_array_empty(&cmd->info, &cmd->root);
 406         if (r < 0)
 407                 goto bad;
 408
 409         if (separate_dirty_bits(cmd)) {
 410                 dm_disk_bitset_init(cmd->tm, &cmd->dirty_info);
 411                 r = dm_bitset_empty(&cmd->dirty_info, &cmd->dirty_root);
 412                 if (r < 0)
 413                         goto bad;
 414         }
 415
 416         dm_disk_bitset_init(cmd->tm, &cmd->discard_info);
 417         r = dm_bitset_empty(&cmd->discard_info, &cmd->discard_root);
 418         if (r < 0)
 419                 goto bad;
 420
 421         cmd->discard_block_size = 0;
 422         cmd->discard_nr_blocks = 0;
 423
 424         r = __write_initial_superblock(cmd);
 425         if (r)
 426                 goto bad;
 427
 428         cmd->clean_when_opened = true;
 429         return 0;
 430
 431 bad:
 432         dm_tm_destroy(cmd->tm);
 433         dm_sm_destroy(cmd->metadata_sm);
 434
 435         return r;
 436 }
 437
 438 static int __check_incompat_features(struct cache_disk_superblock *disk_super,
 439                                      struct dm_cache_metadata *cmd)
 440 {
 441         uint32_t incompat_flags, features;
 442
 443         incompat_flags = le32_to_cpu(disk_super->incompat_flags);
 444         features = incompat_flags & ~DM_CACHE_FEATURE_INCOMPAT_SUPP;
 445         if (features) {
 446                 DMERR("could not access metadata due to unsupported optional features (%lx).",
 447                       (unsigned long)features);
 448                 return -EINVAL;
 449         }
 450
 451         /*
 452          * Check for read-only metadata to skip the following RDWR checks.
 453          */
 454         if (bdev_read_only(cmd->bdev))
 455                 return 0;
 456
 457         features = le32_to_cpu(disk_super->compat_ro_flags) & ~DM_CACHE_FEATURE_COMPAT_RO_SUPP;
 458         if (features) {
 459                 DMERR("could not access metadata RDWR due to unsupported optional features (%lx).",
 460                       (unsigned long)features);
 461                 return -EINVAL;
 462         }
 463
 464         return 0;
 465 }
 466
 467 static int __open_metadata(struct dm_cache_metadata *cmd)
 468 {
 469         int r;
 470         struct dm_block *sblock;
 471         struct cache_disk_superblock *disk_super;
 472         unsigned long sb_flags;
 473
 474         r = superblock_read_lock(cmd, &sblock);
 475         if (r < 0) {
 476                 DMERR("couldn't read lock superblock");
 477                 return r;
 478         }
 479
 480         disk_super = dm_block_data(sblock);
 481
 482         /* Verify the data block size hasn't changed */
 483         if (le32_to_cpu(disk_super->data_block_size) != cmd->data_block_size) {
 484                 DMERR("changing the data block size (from %u to %llu) is not supported",
 485                       le32_to_cpu(disk_super->data_block_size),
 486                       (unsigned long long)cmd->data_block_size);
 487                 r = -EINVAL;
 488                 goto bad;
 489         }
 490
 491         r = __check_incompat_features(disk_super, cmd);
 492         if (r < 0)
 493                 goto bad;
 494
 495         r = dm_tm_open_with_sm(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
 496                                disk_super->metadata_space_map_root,
 497                                sizeof(disk_super->metadata_space_map_root),
 498                                &cmd->tm, &cmd->metadata_sm);
 499         if (r < 0) {
 500                 DMERR("tm_open_with_sm failed");
 501                 goto bad;
 502         }
 503
 504         __setup_mapping_info(cmd);
 505         dm_disk_bitset_init(cmd->tm, &cmd->dirty_info);
 506         dm_disk_bitset_init(cmd->tm, &cmd->discard_info);
 507         sb_flags = le32_to_cpu(disk_super->flags);
 508         cmd->clean_when_opened = test_bit(CLEAN_SHUTDOWN, &sb_flags);
 509         dm_bm_unlock(sblock);
 510
 511         return 0;
 512
 513 bad:
 514         dm_bm_unlock(sblock);
 515         return r;
 516 }
 517
 518 static int __open_or_format_metadata(struct dm_cache_metadata *cmd,
 519                                      bool format_device)
 520 {
 521         int r;
 522         bool unformatted = false;
 523
 524         r = __superblock_all_zeroes(cmd->bm, &unformatted);
 525         if (r)
 526                 return r;
 527
 528         if (unformatted)
 529                 return format_device ? __format_metadata(cmd) : -EPERM;
 530
 531         return __open_metadata(cmd);
 532 }
 533
 534 static int __create_persistent_data_objects(struct dm_cache_metadata *cmd,
 535                                             bool may_format_device)
 536 {
 537         int r;
 538
 539         cmd->bm = dm_block_manager_create(cmd->bdev, DM_CACHE_METADATA_BLOCK_SIZE << SECTOR_SHIFT,
 540                                           CACHE_MAX_CONCURRENT_LOCKS);
 541         if (IS_ERR(cmd->bm)) {
 542                 DMERR("could not create block manager");
 543                 r = PTR_ERR(cmd->bm);
 544                 cmd->bm = NULL;
 545                 return r;
 546         }
 547
 548         r = __open_or_format_metadata(cmd, may_format_device);
 549         if (r) {
 550                 dm_block_manager_destroy(cmd->bm);
 551                 cmd->bm = NULL;
 552         }
 553
 554         return r;
 555 }
 556
 557 static void __destroy_persistent_data_objects(struct dm_cache_metadata *cmd,
 558                                               bool destroy_bm)
 559 {
 560         dm_sm_destroy(cmd->metadata_sm);
 561         dm_tm_destroy(cmd->tm);
 562         if (destroy_bm)
 563                 dm_block_manager_destroy(cmd->bm);
 564 }
 565
 566 typedef unsigned long (*flags_mutator)(unsigned long);
 567
 568 static void update_flags(struct cache_disk_superblock *disk_super,
 569                          flags_mutator mutator)
 570 {
 571         uint32_t sb_flags = mutator(le32_to_cpu(disk_super->flags));
 572
 573         disk_super->flags = cpu_to_le32(sb_flags);
 574 }
 575
 576 static unsigned long set_clean_shutdown(unsigned long flags)
 577 {
 578         set_bit(CLEAN_SHUTDOWN, &flags);
 579         return flags;
 580 }
 581
 582 static unsigned long clear_clean_shutdown(unsigned long flags)
 583 {
 584         clear_bit(CLEAN_SHUTDOWN, &flags);
 585         return flags;
 586 }
 587
 588 static void read_superblock_fields(struct dm_cache_metadata *cmd,
 589                                    struct cache_disk_superblock *disk_super)
 590 {
 591         cmd->version = le32_to_cpu(disk_super->version);
 592         cmd->flags = le32_to_cpu(disk_super->flags);
 593         cmd->root = le64_to_cpu(disk_super->mapping_root);
 594         cmd->hint_root = le64_to_cpu(disk_super->hint_root);
 595         cmd->discard_root = le64_to_cpu(disk_super->discard_root);
 596         cmd->discard_block_size = le64_to_cpu(disk_super->discard_block_size);
 597         cmd->discard_nr_blocks = to_dblock(le64_to_cpu(disk_super->discard_nr_blocks));
 598         cmd->data_block_size = le32_to_cpu(disk_super->data_block_size);
 599         cmd->cache_blocks = to_cblock(le32_to_cpu(disk_super->cache_blocks));
 600         strscpy(cmd->policy_name, disk_super->policy_name, sizeof(cmd->policy_name));
 601         cmd->policy_version[0] = le32_to_cpu(disk_super->policy_version[0]);
 602         cmd->policy_version[1] = le32_to_cpu(disk_super->policy_version[1]);
 603         cmd->policy_version[2] = le32_to_cpu(disk_super->policy_version[2]);
 604         cmd->policy_hint_size = le32_to_cpu(disk_super->policy_hint_size);
 605
 606         cmd->stats.read_hits = le32_to_cpu(disk_super->read_hits);
 607         cmd->stats.read_misses = le32_to_cpu(disk_super->read_misses);
 608         cmd->stats.write_hits = le32_to_cpu(disk_super->write_hits);
 609         cmd->stats.write_misses = le32_to_cpu(disk_super->write_misses);
 610
 611         if (separate_dirty_bits(cmd))
 612                 cmd->dirty_root = le64_to_cpu(disk_super->dirty_root);
 613
 614         cmd->changed = false;
 615 }
 616
 617 /*
 618  * The mutator updates the superblock flags.
 619  */
 620 static int __begin_transaction_flags(struct dm_cache_metadata *cmd,
 621                                      flags_mutator mutator)
 622 {
 623         int r;
 624         struct cache_disk_superblock *disk_super;
 625         struct dm_block *sblock;
 626
 627         r = superblock_lock(cmd, &sblock);
 628         if (r)
 629                 return r;
 630
 631         disk_super = dm_block_data(sblock);
 632         update_flags(disk_super, mutator);
 633         read_superblock_fields(cmd, disk_super);
 634         dm_bm_unlock(sblock);
 635
 636         return dm_bm_flush(cmd->bm);
 637 }
 638
 639 static int __begin_transaction(struct dm_cache_metadata *cmd)
 640 {
 641         int r;
 642         struct cache_disk_superblock *disk_super;
 643         struct dm_block *sblock;
 644
 645         /*
 646          * We re-read the superblock every time.  Shouldn't need to do this
 647          * really.
 648          */
 649         r = superblock_read_lock(cmd, &sblock);
 650         if (r)
 651                 return r;
 652
 653         disk_super = dm_block_data(sblock);
 654         read_superblock_fields(cmd, disk_super);
 655         dm_bm_unlock(sblock);
 656
 657         return 0;
 658 }
 659
 660 static int __commit_transaction(struct dm_cache_metadata *cmd,
 661                                 flags_mutator mutator)
 662 {
 663         int r;
 664         struct cache_disk_superblock *disk_super;
 665         struct dm_block *sblock;
 666
 667         /*
 668          * We need to know if the cache_disk_superblock exceeds a 512-byte sector.
 669          */
 670         BUILD_BUG_ON(sizeof(struct cache_disk_superblock) > 512);
 671
 672         if (separate_dirty_bits(cmd)) {
 673                 r = dm_bitset_flush(&cmd->dirty_info, cmd->dirty_root,
 674                                     &cmd->dirty_root);
 675                 if (r)
 676                         return r;
 677         }
 678
 679         r = dm_bitset_flush(&cmd->discard_info, cmd->discard_root,
 680                             &cmd->discard_root);
 681         if (r)
 682                 return r;
 683
 684         r = dm_tm_pre_commit(cmd->tm);
 685         if (r < 0)
 686                 return r;
 687
 688         r = __save_sm_root(cmd);
 689         if (r)
 690                 return r;
 691
 692         r = superblock_lock(cmd, &sblock);
 693         if (r)
 694                 return r;
 695
 696         disk_super = dm_block_data(sblock);
 697
 698         disk_super->flags = cpu_to_le32(cmd->flags);
 699         if (mutator)
 700                 update_flags(disk_super, mutator);
 701
 702         disk_super->mapping_root = cpu_to_le64(cmd->root);
 703         if (separate_dirty_bits(cmd))
 704                 disk_super->dirty_root = cpu_to_le64(cmd->dirty_root);
 705         disk_super->hint_root = cpu_to_le64(cmd->hint_root);
 706         disk_super->discard_root = cpu_to_le64(cmd->discard_root);
 707         disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size);
 708         disk_super->discard_nr_blocks = cpu_to_le64(from_dblock(cmd->discard_nr_blocks));
 709         disk_super->cache_blocks = cpu_to_le32(from_cblock(cmd->cache_blocks));
 710         strscpy(disk_super->policy_name, cmd->policy_name, sizeof(disk_super->policy_name));
 711         disk_super->policy_version[0] = cpu_to_le32(cmd->policy_version[0]);
 712         disk_super->policy_version[1] = cpu_to_le32(cmd->policy_version[1]);
 713         disk_super->policy_version[2] = cpu_to_le32(cmd->policy_version[2]);
 714         disk_super->policy_hint_size = cpu_to_le32(cmd->policy_hint_size);
 715
 716         disk_super->read_hits = cpu_to_le32(cmd->stats.read_hits);
 717         disk_super->read_misses = cpu_to_le32(cmd->stats.read_misses);
 718         disk_super->write_hits = cpu_to_le32(cmd->stats.write_hits);
 719         disk_super->write_misses = cpu_to_le32(cmd->stats.write_misses);
 720         __copy_sm_root(cmd, disk_super);
 721
 722         return dm_tm_commit(cmd->tm, sblock);
 723 }
 724
 725 /*----------------------------------------------------------------*/
 726
 727 /*
 728  * The mappings are held in a dm-array that has 64-bit values stored in
 729  * little-endian format.  The index is the cblock, the high 48bits of the
 730  * value are the oblock and the low 16 bit the flags.
 731  */
 732 #define FLAGS_MASK ((1 << 16) - 1)
 733
 734 static __le64 pack_value(dm_oblock_t block, unsigned int flags)
 735 {
 736         uint64_t value = from_oblock(block);
 737
 738         value <<= 16;
 739         value = value | (flags & FLAGS_MASK);
 740         return cpu_to_le64(value);
 741 }
 742
 743 static void unpack_value(__le64 value_le, dm_oblock_t *block, unsigned int *flags)
 744 {
 745         uint64_t value = le64_to_cpu(value_le);
 746         uint64_t b = value >> 16;
 747
 748         *block = to_oblock(b);
 749         *flags = value & FLAGS_MASK;
 750 }
 751
 752 /*----------------------------------------------------------------*/
 753
 754 static struct dm_cache_metadata *metadata_open(struct block_device *bdev,
 755                                                sector_t data_block_size,
 756                                                bool may_format_device,
 757                                                size_t policy_hint_size,
 758                                                unsigned int metadata_version)
 759 {
 760         int r;
 761         struct dm_cache_metadata *cmd;
 762
 763         cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
 764         if (!cmd) {
 765                 DMERR("could not allocate metadata struct");
 766                 return ERR_PTR(-ENOMEM);
 767         }
 768
 769         cmd->version = metadata_version;
 770         refcount_set(&cmd->ref_count, 1);
 771         init_rwsem(&cmd->root_lock);
 772         cmd->bdev = bdev;
 773         cmd->data_block_size = data_block_size;
 774         cmd->cache_blocks = 0;
 775         cmd->policy_hint_size = policy_hint_size;
 776         cmd->changed = true;
 777         cmd->fail_io = false;
 778
 779         r = __create_persistent_data_objects(cmd, may_format_device);
 780         if (r) {
 781                 kfree(cmd);
 782                 return ERR_PTR(r);
 783         }
 784
 785         r = __begin_transaction_flags(cmd, clear_clean_shutdown);
 786         if (r < 0) {
 787                 dm_cache_metadata_close(cmd);
 788                 return ERR_PTR(r);
 789         }
 790
 791         return cmd;
 792 }
 793
 794 /*
 795  * We keep a little list of ref counted metadata objects to prevent two
 796  * different target instances creating separate bufio instances.  This is
 797  * an issue if a table is reloaded before the suspend.
 798  */
 799 static DEFINE_MUTEX(table_lock);
 800 static LIST_HEAD(table);
 801
 802 static struct dm_cache_metadata *lookup(struct block_device *bdev)
 803 {
 804         struct dm_cache_metadata *cmd;
 805
 806         list_for_each_entry(cmd, &table, list)
 807                 if (cmd->bdev == bdev) {
 808                         refcount_inc(&cmd->ref_count);
 809                         return cmd;
 810                 }
 811
 812         return NULL;
 813 }
 814
 815 static struct dm_cache_metadata *lookup_or_open(struct block_device *bdev,
 816                                                 sector_t data_block_size,
 817                                                 bool may_format_device,
 818                                                 size_t policy_hint_size,
 819                                                 unsigned int metadata_version)
 820 {
 821         struct dm_cache_metadata *cmd, *cmd2;
 822
 823         mutex_lock(&table_lock);
 824         cmd = lookup(bdev);
 825         mutex_unlock(&table_lock);
 826
 827         if (cmd)
 828                 return cmd;
 829
 830         cmd = metadata_open(bdev, data_block_size, may_format_device,
 831                             policy_hint_size, metadata_version);
 832         if (!IS_ERR(cmd)) {
 833                 mutex_lock(&table_lock);
 834                 cmd2 = lookup(bdev);
 835                 if (cmd2) {
 836                         mutex_unlock(&table_lock);
 837                         __destroy_persistent_data_objects(cmd, true);
 838                         kfree(cmd);
 839                         return cmd2;
 840                 }
 841                 list_add(&cmd->list, &table);
 842                 mutex_unlock(&table_lock);
 843         }
 844
 845         return cmd;
 846 }
 847
 848 static bool same_params(struct dm_cache_metadata *cmd, sector_t data_block_size)
 849 {
 850         if (cmd->data_block_size != data_block_size) {
 851                 DMERR("data_block_size (%llu) different from that in metadata (%llu)",
 852                       (unsigned long long) data_block_size,
 853                       (unsigned long long) cmd->data_block_size);
 854                 return false;
 855         }
 856
 857         return true;
 858 }
 859
 860 struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev,
 861                                                  sector_t data_block_size,
 862                                                  bool may_format_device,
 863                                                  size_t policy_hint_size,
 864                                                  unsigned int metadata_version)
 865 {
 866         struct dm_cache_metadata *cmd = lookup_or_open(bdev, data_block_size, may_format_device,
 867                                                        policy_hint_size, metadata_version);
 868
 869         if (!IS_ERR(cmd) && !same_params(cmd, data_block_size)) {
 870                 dm_cache_metadata_close(cmd);
 871                 return ERR_PTR(-EINVAL);
 872         }
 873
 874         return cmd;
 875 }
 876
 877 void dm_cache_metadata_close(struct dm_cache_metadata *cmd)
 878 {
 879         if (refcount_dec_and_test(&cmd->ref_count)) {
 880                 mutex_lock(&table_lock);
 881                 list_del(&cmd->list);
 882                 mutex_unlock(&table_lock);
 883
 884                 if (!cmd->fail_io)
 885                         __destroy_persistent_data_objects(cmd, true);
 886                 kfree(cmd);
 887         }
 888 }
 889
 890 /*
 891  * Checks that the given cache block is either unmapped or clean.
 892  */
 893 static int block_clean_combined_dirty(struct dm_cache_metadata *cmd, dm_cblock_t b,
 894                                       bool *result)
 895 {
 896         int r;
 897         __le64 value;
 898         dm_oblock_t ob;
 899         unsigned int flags;
 900
 901         r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(b), &value);
 902         if (r)
 903                 return r;
 904
 905         unpack_value(value, &ob, &flags);
 906         *result = !((flags & M_VALID) && (flags & M_DIRTY));
 907
 908         return 0;
 909 }
 910
 911 static int blocks_are_clean_combined_dirty(struct dm_cache_metadata *cmd,
 912                                            dm_cblock_t begin, dm_cblock_t end,
 913                                            bool *result)
 914 {
 915         int r;
 916         *result = true;
 917
 918         while (begin != end) {
 919                 r = block_clean_combined_dirty(cmd, begin, result);
 920                 if (r) {
 921                         DMERR("block_clean_combined_dirty failed");
 922                         return r;
 923                 }
 924
 925                 if (!*result) {
 926                         DMERR("cache block %llu is dirty",
 927                               (unsigned long long) from_cblock(begin));
 928                         return 0;
 929                 }
 930
 931                 begin = to_cblock(from_cblock(begin) + 1);
 932         }
 933
 934         return 0;
 935 }
 936
 937 static int blocks_are_clean_separate_dirty(struct dm_cache_metadata *cmd,
 938                                            dm_cblock_t begin, dm_cblock_t end,
 939                                            bool *result)
 940 {
 941         int r;
 942         bool dirty_flag;
 943         *result = true;
 944
 945         if (from_cblock(cmd->cache_blocks) == 0)
 946                 /* Nothing to do */
 947                 return 0;
 948
 949         r = dm_bitset_cursor_begin(&cmd->dirty_info, cmd->dirty_root,
 950                                    from_cblock(cmd->cache_blocks), &cmd->dirty_cursor);
 951         if (r) {
 952                 DMERR("%s: dm_bitset_cursor_begin for dirty failed", __func__);
 953                 return r;
 954         }
 955
 956         r = dm_bitset_cursor_skip(&cmd->dirty_cursor, from_cblock(begin));
 957         if (r) {
 958                 DMERR("%s: dm_bitset_cursor_skip for dirty failed", __func__);
 959                 dm_bitset_cursor_end(&cmd->dirty_cursor);
 960                 return r;
 961         }
 962
 963         while (begin != end) {
 964                 /*
 965                  * We assume that unmapped blocks have their dirty bit
 966                  * cleared.
 967                  */
 968                 dirty_flag = dm_bitset_cursor_get_value(&cmd->dirty_cursor);
 969                 if (dirty_flag) {
 970                         DMERR("%s: cache block %llu is dirty", __func__,
 971                               (unsigned long long) from_cblock(begin));
 972                         dm_bitset_cursor_end(&cmd->dirty_cursor);
 973                         *result = false;
 974                         return 0;
 975                 }
 976
 977                 begin = to_cblock(from_cblock(begin) + 1);
 978                 if (begin == end)
 979                         break;
 980
 981                 r = dm_bitset_cursor_next(&cmd->dirty_cursor);
 982                 if (r) {
 983                         DMERR("%s: dm_bitset_cursor_next for dirty failed", __func__);
 984                         dm_bitset_cursor_end(&cmd->dirty_cursor);
 985                         return r;
 986                 }
 987         }
 988
 989         dm_bitset_cursor_end(&cmd->dirty_cursor);
 990
 991         return 0;
 992 }
 993
 994 static int blocks_are_unmapped_or_clean(struct dm_cache_metadata *cmd,
 995                                         dm_cblock_t begin, dm_cblock_t end,
 996                                         bool *result)
 997 {
 998         if (separate_dirty_bits(cmd))
 999                 return blocks_are_clean_separate_dirty(cmd, begin, end, result);
1000         else
1001                 return blocks_are_clean_combined_dirty(cmd, begin, end, result);
1002 }
1003
1004 static bool cmd_write_lock(struct dm_cache_metadata *cmd)
1005 {
1006         down_write(&cmd->root_lock);
1007         if (cmd->fail_io || dm_bm_is_read_only(cmd->bm)) {
1008                 up_write(&cmd->root_lock);
1009                 return false;
1010         }
1011         return true;
1012 }
1013
1014 #define WRITE_LOCK(cmd)                         \
1015         do {                                    \
1016                 if (!cmd_write_lock((cmd)))     \
1017                         return -EINVAL;         \
1018         } while (0)
1019
1020 #define WRITE_LOCK_VOID(cmd)                    \
1021         do {                                    \
1022                 if (!cmd_write_lock((cmd)))     \
1023                         return;                 \
1024         } while (0)
1025
1026 #define WRITE_UNLOCK(cmd) \
1027         up_write(&(cmd)->root_lock)
1028
1029 static bool cmd_read_lock(struct dm_cache_metadata *cmd)
1030 {
1031         down_read(&cmd->root_lock);
1032         if (cmd->fail_io) {
1033                 up_read(&cmd->root_lock);
1034                 return false;
1035         }
1036         return true;
1037 }
1038
1039 #define READ_LOCK(cmd)                          \
1040         do {                                    \
1041                 if (!cmd_read_lock((cmd)))      \
1042                         return -EINVAL;         \
1043         } while (0)
1044
1045 #define READ_LOCK_VOID(cmd)                     \
1046         do {                                    \
1047                 if (!cmd_read_lock((cmd)))      \
1048                         return;                 \
1049         } while (0)
1050
1051 #define READ_UNLOCK(cmd) \
1052         up_read(&(cmd)->root_lock)
1053
1054 int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size)
1055 {
1056         int r;
1057         bool clean;
1058         __le64 null_mapping = pack_value(0, 0);
1059
1060         WRITE_LOCK(cmd);
1061         __dm_bless_for_disk(&null_mapping);
1062
1063         if (from_cblock(new_cache_size) < from_cblock(cmd->cache_blocks)) {
1064                 r = blocks_are_unmapped_or_clean(cmd, new_cache_size, cmd->cache_blocks, &clean);
1065                 if (r) {
1066                         __dm_unbless_for_disk(&null_mapping);
1067                         goto out;
1068                 }
1069
1070                 if (!clean) {
1071                         DMERR("unable to shrink cache due to dirty blocks");
1072                         r = -EINVAL;
1073                         __dm_unbless_for_disk(&null_mapping);
1074                         goto out;
1075                 }
1076         }
1077
1078         r = dm_array_resize(&cmd->info, cmd->root, from_cblock(cmd->cache_blocks),
1079                             from_cblock(new_cache_size),
1080                             &null_mapping, &cmd->root);
1081         if (r)
1082                 goto out;
1083
1084         if (separate_dirty_bits(cmd)) {
1085                 r = dm_bitset_resize(&cmd->dirty_info, cmd->dirty_root,
1086                                      from_cblock(cmd->cache_blocks), from_cblock(new_cache_size),
1087                                      false, &cmd->dirty_root);
1088                 if (r)
1089                         goto out;
1090         }
1091
1092         cmd->cache_blocks = new_cache_size;
1093         cmd->changed = true;
1094
1095 out:
1096         WRITE_UNLOCK(cmd);
1097
1098         return r;
1099 }
1100
1101 int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd,
1102                                    sector_t discard_block_size,
1103                                    dm_dblock_t new_nr_entries)
1104 {
1105         int r;
1106
1107         WRITE_LOCK(cmd);
1108         r = dm_bitset_resize(&cmd->discard_info,
1109                              cmd->discard_root,
1110                              from_dblock(cmd->discard_nr_blocks),
1111                              from_dblock(new_nr_entries),
1112                              false, &cmd->discard_root);
1113         if (!r) {
1114                 cmd->discard_block_size = discard_block_size;
1115                 cmd->discard_nr_blocks = new_nr_entries;
1116         }
1117
1118         cmd->changed = true;
1119         WRITE_UNLOCK(cmd);
1120
1121         return r;
1122 }
1123
1124 static int __set_discard(struct dm_cache_metadata *cmd, dm_dblock_t b)
1125 {
1126         return dm_bitset_set_bit(&cmd->discard_info, cmd->discard_root,
1127                                  from_dblock(b), &cmd->discard_root);
1128 }
1129
1130 static int __clear_discard(struct dm_cache_metadata *cmd, dm_dblock_t b)
1131 {
1132         return dm_bitset_clear_bit(&cmd->discard_info, cmd->discard_root,
1133                                    from_dblock(b), &cmd->discard_root);
1134 }
1135
1136 static int __discard(struct dm_cache_metadata *cmd,
1137                      dm_dblock_t dblock, bool discard)
1138 {
1139         int r;
1140
1141         r = (discard ? __set_discard : __clear_discard)(cmd, dblock);
1142         if (r)
1143                 return r;
1144
1145         cmd->changed = true;
1146         return 0;
1147 }
1148
1149 int dm_cache_set_discard(struct dm_cache_metadata *cmd,
1150                          dm_dblock_t dblock, bool discard)
1151 {
1152         int r;
1153
1154         WRITE_LOCK(cmd);
1155         r = __discard(cmd, dblock, discard);
1156         WRITE_UNLOCK(cmd);
1157
1158         return r;
1159 }
1160
1161 static int __load_discards(struct dm_cache_metadata *cmd,
1162                            load_discard_fn fn, void *context)
1163 {
1164         int r = 0;
1165         uint32_t b;
1166         struct dm_bitset_cursor c;
1167
1168         if (from_dblock(cmd->discard_nr_blocks) == 0)
1169                 /* nothing to do */
1170                 return 0;
1171
1172         if (cmd->clean_when_opened) {
1173                 r = dm_bitset_flush(&cmd->discard_info, cmd->discard_root, &cmd->discard_root);
1174                 if (r)
1175                         return r;
1176
1177                 r = dm_bitset_cursor_begin(&cmd->discard_info, cmd->discard_root,
1178                                            from_dblock(cmd->discard_nr_blocks), &c);
1179                 if (r)
1180                         return r;
1181
1182                 for (b = 0; ; b++) {
1183                         r = fn(context, cmd->discard_block_size, to_dblock(b),
1184                                dm_bitset_cursor_get_value(&c));
1185                         if (r)
1186                                 break;
1187
1188                         if (b >= (from_dblock(cmd->discard_nr_blocks) - 1))
1189                                 break;
1190
1191                         r = dm_bitset_cursor_next(&c);
1192                         if (r)
1193                                 break;
1194                 }
1195
1196                 dm_bitset_cursor_end(&c);
1197
1198         } else {
1199                 for (b = 0; b < from_dblock(cmd->discard_nr_blocks); b++) {
1200                         r = fn(context, cmd->discard_block_size, to_dblock(b), false);
1201                         if (r)
1202                                 return r;
1203                 }
1204         }
1205
1206         return r;
1207 }
1208
1209 int dm_cache_load_discards(struct dm_cache_metadata *cmd,
1210                            load_discard_fn fn, void *context)
1211 {
1212         int r;
1213
1214         READ_LOCK(cmd);
1215         r = __load_discards(cmd, fn, context);
1216         READ_UNLOCK(cmd);
1217
1218         return r;
1219 }
1220
1221 static int __remove(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
1222 {
1223         int r;
1224         __le64 value = pack_value(0, 0);
1225
1226         __dm_bless_for_disk(&value);
1227         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1228                                &value, &cmd->root);
1229         if (r)
1230                 return r;
1231
1232         cmd->changed = true;
1233         return 0;
1234 }
1235
1236 int dm_cache_remove_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
1237 {
1238         int r;
1239
1240         WRITE_LOCK(cmd);
1241         r = __remove(cmd, cblock);
1242         WRITE_UNLOCK(cmd);
1243
1244         return r;
1245 }
1246
1247 static int __insert(struct dm_cache_metadata *cmd,
1248                     dm_cblock_t cblock, dm_oblock_t oblock)
1249 {
1250         int r;
1251         __le64 value = pack_value(oblock, M_VALID);
1252
1253         __dm_bless_for_disk(&value);
1254
1255         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1256                                &value, &cmd->root);
1257         if (r)
1258                 return r;
1259
1260         cmd->changed = true;
1261         return 0;
1262 }
1263
1264 int dm_cache_insert_mapping(struct dm_cache_metadata *cmd,
1265                             dm_cblock_t cblock, dm_oblock_t oblock)
1266 {
1267         int r;
1268
1269         WRITE_LOCK(cmd);
1270         r = __insert(cmd, cblock, oblock);
1271         WRITE_UNLOCK(cmd);
1272
1273         return r;
1274 }
1275
1276 static bool policy_unchanged(struct dm_cache_metadata *cmd,
1277                              struct dm_cache_policy *policy)
1278 {
1279         const char *policy_name = dm_cache_policy_get_name(policy);
1280         const unsigned int *policy_version = dm_cache_policy_get_version(policy);
1281         size_t policy_hint_size = dm_cache_policy_get_hint_size(policy);
1282
1283         /*
1284          * Ensure policy names match.
1285          */
1286         if (strncmp(cmd->policy_name, policy_name, sizeof(cmd->policy_name)))
1287                 return false;
1288
1289         /*
1290          * Ensure policy major versions match.
1291          */
1292         if (cmd->policy_version[0] != policy_version[0])
1293                 return false;
1294
1295         /*
1296          * Ensure policy hint sizes match.
1297          */
1298         if (cmd->policy_hint_size != policy_hint_size)
1299                 return false;
1300
1301         return true;
1302 }
1303
1304 static bool hints_array_initialized(struct dm_cache_metadata *cmd)
1305 {
1306         return cmd->hint_root && cmd->policy_hint_size;
1307 }
1308
1309 static bool hints_array_available(struct dm_cache_metadata *cmd,
1310                                   struct dm_cache_policy *policy)
1311 {
1312         return cmd->clean_when_opened && policy_unchanged(cmd, policy) &&
1313                 hints_array_initialized(cmd);
1314 }
1315
1316 static int __load_mapping_v1(struct dm_cache_metadata *cmd,
1317                              uint64_t cb, bool hints_valid,
1318                              struct dm_array_cursor *mapping_cursor,
1319                              struct dm_array_cursor *hint_cursor,
1320                              load_mapping_fn fn, void *context)
1321 {
1322         int r = 0;
1323
1324         __le64 mapping;
1325         __le32 hint = 0;
1326
1327         __le64 *mapping_value_le;
1328         __le32 *hint_value_le;
1329
1330         dm_oblock_t oblock;
1331         unsigned int flags;
1332         bool dirty = true;
1333
1334         dm_array_cursor_get_value(mapping_cursor, (void **) &mapping_value_le);
1335         memcpy(&mapping, mapping_value_le, sizeof(mapping));
1336         unpack_value(mapping, &oblock, &flags);
1337
1338         if (flags & M_VALID) {
1339                 if (hints_valid) {
1340                         dm_array_cursor_get_value(hint_cursor, (void **) &hint_value_le);
1341                         memcpy(&hint, hint_value_le, sizeof(hint));
1342                 }
1343                 if (cmd->clean_when_opened)
1344                         dirty = flags & M_DIRTY;
1345
1346                 r = fn(context, oblock, to_cblock(cb), dirty,
1347                        le32_to_cpu(hint), hints_valid);
1348                 if (r) {
1349                         DMERR("policy couldn't load cache block %llu",
1350                               (unsigned long long) from_cblock(to_cblock(cb)));
1351                 }
1352         }
1353
1354         return r;
1355 }
1356
1357 static int __load_mapping_v2(struct dm_cache_metadata *cmd,
1358                              uint64_t cb, bool hints_valid,
1359                              struct dm_array_cursor *mapping_cursor,
1360                              struct dm_array_cursor *hint_cursor,
1361                              struct dm_bitset_cursor *dirty_cursor,
1362                              load_mapping_fn fn, void *context)
1363 {
1364         int r = 0;
1365
1366         __le64 mapping;
1367         __le32 hint = 0;
1368
1369         __le64 *mapping_value_le;
1370         __le32 *hint_value_le;
1371
1372         dm_oblock_t oblock;
1373         unsigned int flags;
1374         bool dirty = true;
1375
1376         dm_array_cursor_get_value(mapping_cursor, (void **) &mapping_value_le);
1377         memcpy(&mapping, mapping_value_le, sizeof(mapping));
1378         unpack_value(mapping, &oblock, &flags);
1379
1380         if (flags & M_VALID) {
1381                 if (hints_valid) {
1382                         dm_array_cursor_get_value(hint_cursor, (void **) &hint_value_le);
1383                         memcpy(&hint, hint_value_le, sizeof(hint));
1384                 }
1385                 if (cmd->clean_when_opened)
1386                         dirty = dm_bitset_cursor_get_value(dirty_cursor);
1387
1388                 r = fn(context, oblock, to_cblock(cb), dirty,
1389                        le32_to_cpu(hint), hints_valid);
1390                 if (r) {
1391                         DMERR("policy couldn't load cache block %llu",
1392                               (unsigned long long) from_cblock(to_cblock(cb)));
1393                 }
1394         }
1395
1396         return r;
1397 }
1398
1399 static int __load_mappings(struct dm_cache_metadata *cmd,
1400                            struct dm_cache_policy *policy,
1401                            load_mapping_fn fn, void *context)
1402 {
1403         int r;
1404         uint64_t cb;
1405
1406         bool hints_valid = hints_array_available(cmd, policy);
1407
1408         if (from_cblock(cmd->cache_blocks) == 0)
1409                 /* Nothing to do */
1410                 return 0;
1411
1412         r = dm_array_cursor_begin(&cmd->info, cmd->root, &cmd->mapping_cursor);
1413         if (r)
1414                 return r;
1415
1416         if (hints_valid) {
1417                 r = dm_array_cursor_begin(&cmd->hint_info, cmd->hint_root, &cmd->hint_cursor);
1418                 if (r) {
1419                         dm_array_cursor_end(&cmd->mapping_cursor);
1420                         return r;
1421                 }
1422         }
1423
1424         if (separate_dirty_bits(cmd)) {
1425                 r = dm_bitset_cursor_begin(&cmd->dirty_info, cmd->dirty_root,
1426                                            from_cblock(cmd->cache_blocks),
1427                                            &cmd->dirty_cursor);
1428                 if (r) {
1429                         dm_array_cursor_end(&cmd->hint_cursor);
1430                         dm_array_cursor_end(&cmd->mapping_cursor);
1431                         return r;
1432                 }
1433         }
1434
1435         for (cb = 0; ; cb++) {
1436                 if (separate_dirty_bits(cmd))
1437                         r = __load_mapping_v2(cmd, cb, hints_valid,
1438                                               &cmd->mapping_cursor,
1439                                               &cmd->hint_cursor,
1440                                               &cmd->dirty_cursor,
1441                                               fn, context);
1442                 else
1443                         r = __load_mapping_v1(cmd, cb, hints_valid,
1444                                               &cmd->mapping_cursor, &cmd->hint_cursor,
1445                                               fn, context);
1446                 if (r)
1447                         goto out;
1448
1449                 /*
1450                  * We need to break out before we move the cursors.
1451                  */
1452                 if (cb >= (from_cblock(cmd->cache_blocks) - 1))
1453                         break;
1454
1455                 r = dm_array_cursor_next(&cmd->mapping_cursor);
1456                 if (r) {
1457                         DMERR("dm_array_cursor_next for mapping failed");
1458                         goto out;
1459                 }
1460
1461                 if (hints_valid) {
1462                         r = dm_array_cursor_next(&cmd->hint_cursor);
1463                         if (r) {
1464                                 dm_array_cursor_end(&cmd->hint_cursor);
1465                                 hints_valid = false;
1466                         }
1467                 }
1468
1469                 if (separate_dirty_bits(cmd)) {
1470                         r = dm_bitset_cursor_next(&cmd->dirty_cursor);
1471                         if (r) {
1472                                 DMERR("dm_bitset_cursor_next for dirty failed");
1473                                 goto out;
1474                         }
1475                 }
1476         }
1477 out:
1478         dm_array_cursor_end(&cmd->mapping_cursor);
1479         if (hints_valid)
1480                 dm_array_cursor_end(&cmd->hint_cursor);
1481
1482         if (separate_dirty_bits(cmd))
1483                 dm_bitset_cursor_end(&cmd->dirty_cursor);
1484
1485         return r;
1486 }
1487
1488 int dm_cache_load_mappings(struct dm_cache_metadata *cmd,
1489                            struct dm_cache_policy *policy,
1490                            load_mapping_fn fn, void *context)
1491 {
1492         int r;
1493
1494         READ_LOCK(cmd);
1495         r = __load_mappings(cmd, policy, fn, context);
1496         READ_UNLOCK(cmd);
1497
1498         return r;
1499 }
1500
1501 int dm_cache_changed_this_transaction(struct dm_cache_metadata *cmd)
1502 {
1503         int r;
1504
1505         READ_LOCK(cmd);
1506         r = cmd->changed;
1507         READ_UNLOCK(cmd);
1508
1509         return r;
1510 }
1511
1512 static int __dirty(struct dm_cache_metadata *cmd, dm_cblock_t cblock, bool dirty)
1513 {
1514         int r;
1515         unsigned int flags;
1516         dm_oblock_t oblock;
1517         __le64 value;
1518
1519         r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(cblock), &value);
1520         if (r)
1521                 return r;
1522
1523         unpack_value(value, &oblock, &flags);
1524
1525         if (((flags & M_DIRTY) && dirty) || (!(flags & M_DIRTY) && !dirty))
1526                 /* nothing to be done */
1527                 return 0;
1528
1529         value = pack_value(oblock, (flags & ~M_DIRTY) | (dirty ? M_DIRTY : 0));
1530         __dm_bless_for_disk(&value);
1531
1532         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1533                                &value, &cmd->root);
1534         if (r)
1535                 return r;
1536
1537         cmd->changed = true;
1538         return 0;
1539
1540 }
1541
1542 static int __set_dirty_bits_v1(struct dm_cache_metadata *cmd, unsigned int nr_bits, unsigned long *bits)
1543 {
1544         int r;
1545         unsigned int i;
1546
1547         for (i = 0; i < nr_bits; i++) {
1548                 r = __dirty(cmd, to_cblock(i), test_bit(i, bits));
1549                 if (r)
1550                         return r;
1551         }
1552
1553         return 0;
1554 }
1555
1556 static int is_dirty_callback(uint32_t index, bool *value, void *context)
1557 {
1558         unsigned long *bits = context;
1559         *value = test_bit(index, bits);
1560         return 0;
1561 }
1562
1563 static int __set_dirty_bits_v2(struct dm_cache_metadata *cmd, unsigned int nr_bits, unsigned long *bits)
1564 {
1565         int r = 0;
1566
1567         /* nr_bits is really just a sanity check */
1568         if (nr_bits != from_cblock(cmd->cache_blocks)) {
1569                 DMERR("dirty bitset is wrong size");
1570                 return -EINVAL;
1571         }
1572
1573         r = dm_bitset_del(&cmd->dirty_info, cmd->dirty_root);
1574         if (r)
1575                 return r;
1576
1577         cmd->changed = true;
1578         return dm_bitset_new(&cmd->dirty_info, &cmd->dirty_root, nr_bits, is_dirty_callback, bits);
1579 }
1580
1581 int dm_cache_set_dirty_bits(struct dm_cache_metadata *cmd,
1582                             unsigned int nr_bits,
1583                             unsigned long *bits)
1584 {
1585         int r;
1586
1587         WRITE_LOCK(cmd);
1588         if (separate_dirty_bits(cmd))
1589                 r = __set_dirty_bits_v2(cmd, nr_bits, bits);
1590         else
1591                 r = __set_dirty_bits_v1(cmd, nr_bits, bits);
1592         WRITE_UNLOCK(cmd);
1593
1594         return r;
1595 }
1596
1597 void dm_cache_metadata_get_stats(struct dm_cache_metadata *cmd,
1598                                  struct dm_cache_statistics *stats)
1599 {
1600         READ_LOCK_VOID(cmd);
1601         *stats = cmd->stats;
1602         READ_UNLOCK(cmd);
1603 }
1604
1605 void dm_cache_metadata_set_stats(struct dm_cache_metadata *cmd,
1606                                  struct dm_cache_statistics *stats)
1607 {
1608         WRITE_LOCK_VOID(cmd);
1609         cmd->stats = *stats;
1610         WRITE_UNLOCK(cmd);
1611 }
1612
1613 int dm_cache_commit(struct dm_cache_metadata *cmd, bool clean_shutdown)
1614 {
1615         int r = -EINVAL;
1616         flags_mutator mutator = (clean_shutdown ? set_clean_shutdown :
1617                                  clear_clean_shutdown);
1618
1619         WRITE_LOCK(cmd);
1620         if (cmd->fail_io)
1621                 goto out;
1622
1623         r = __commit_transaction(cmd, mutator);
1624         if (r)
1625                 goto out;
1626
1627         r = __begin_transaction(cmd);
1628 out:
1629         WRITE_UNLOCK(cmd);
1630         return r;
1631 }
1632
1633 int dm_cache_get_free_metadata_block_count(struct dm_cache_metadata *cmd,
1634                                            dm_block_t *result)
1635 {
1636         int r = -EINVAL;
1637
1638         READ_LOCK(cmd);
1639         if (!cmd->fail_io)
1640                 r = dm_sm_get_nr_free(cmd->metadata_sm, result);
1641         READ_UNLOCK(cmd);
1642
1643         return r;
1644 }
1645
1646 int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd,
1647                                    dm_block_t *result)
1648 {
1649         int r = -EINVAL;
1650
1651         READ_LOCK(cmd);
1652         if (!cmd->fail_io)
1653                 r = dm_sm_get_nr_blocks(cmd->metadata_sm, result);
1654         READ_UNLOCK(cmd);
1655
1656         return r;
1657 }
1658
1659 /*----------------------------------------------------------------*/
1660
1661 static int get_hint(uint32_t index, void *value_le, void *context)
1662 {
1663         uint32_t value;
1664         struct dm_cache_policy *policy = context;
1665
1666         value = policy_get_hint(policy, to_cblock(index));
1667         *((__le32 *) value_le) = cpu_to_le32(value);
1668
1669         return 0;
1670 }
1671
1672 /*
1673  * It's quicker to always delete the hint array, and recreate with
1674  * dm_array_new().
1675  */
1676 static int write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1677 {
1678         int r;
1679         size_t hint_size;
1680         const char *policy_name = dm_cache_policy_get_name(policy);
1681         const unsigned int *policy_version = dm_cache_policy_get_version(policy);
1682
1683         if (!policy_name[0] ||
1684             (strlen(policy_name) > sizeof(cmd->policy_name) - 1))
1685                 return -EINVAL;
1686
1687         strscpy(cmd->policy_name, policy_name, sizeof(cmd->policy_name));
1688         memcpy(cmd->policy_version, policy_version, sizeof(cmd->policy_version));
1689
1690         hint_size = dm_cache_policy_get_hint_size(policy);
1691         if (!hint_size)
1692                 return 0; /* short-circuit hints initialization */
1693         cmd->policy_hint_size = hint_size;
1694
1695         if (cmd->hint_root) {
1696                 r = dm_array_del(&cmd->hint_info, cmd->hint_root);
1697                 if (r)
1698                         return r;
1699         }
1700
1701         return dm_array_new(&cmd->hint_info, &cmd->hint_root,
1702                             from_cblock(cmd->cache_blocks),
1703                             get_hint, policy);
1704 }
1705
1706 int dm_cache_write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1707 {
1708         int r;
1709
1710         WRITE_LOCK(cmd);
1711         r = write_hints(cmd, policy);
1712         WRITE_UNLOCK(cmd);
1713
1714         return r;
1715 }
1716
1717 int dm_cache_metadata_all_clean(struct dm_cache_metadata *cmd, bool *result)
1718 {
1719         int r;
1720
1721         READ_LOCK(cmd);
1722         r = blocks_are_unmapped_or_clean(cmd, 0, cmd->cache_blocks, result);
1723         READ_UNLOCK(cmd);
1724
1725         return r;
1726 }
1727
1728 void dm_cache_metadata_set_read_only(struct dm_cache_metadata *cmd)
1729 {
1730         WRITE_LOCK_VOID(cmd);
1731         dm_bm_set_read_only(cmd->bm);
1732         WRITE_UNLOCK(cmd);
1733 }
1734
1735 void dm_cache_metadata_set_read_write(struct dm_cache_metadata *cmd)
1736 {
1737         WRITE_LOCK_VOID(cmd);
1738         dm_bm_set_read_write(cmd->bm);
1739         WRITE_UNLOCK(cmd);
1740 }
1741
1742 int dm_cache_metadata_set_needs_check(struct dm_cache_metadata *cmd)
1743 {
1744         int r;
1745         struct dm_block *sblock;
1746         struct cache_disk_superblock *disk_super;
1747
1748         WRITE_LOCK(cmd);
1749         set_bit(NEEDS_CHECK, &cmd->flags);
1750
1751         r = superblock_lock(cmd, &sblock);
1752         if (r) {
1753                 DMERR("couldn't read superblock");
1754                 goto out;
1755         }
1756
1757         disk_super = dm_block_data(sblock);
1758         disk_super->flags = cpu_to_le32(cmd->flags);
1759
1760         dm_bm_unlock(sblock);
1761
1762 out:
1763         WRITE_UNLOCK(cmd);
1764         return r;
1765 }
1766
1767 int dm_cache_metadata_needs_check(struct dm_cache_metadata *cmd, bool *result)
1768 {
1769         READ_LOCK(cmd);
1770         *result = !!test_bit(NEEDS_CHECK, &cmd->flags);
1771         READ_UNLOCK(cmd);
1772
1773         return 0;
1774 }
1775
1776 int dm_cache_metadata_abort(struct dm_cache_metadata *cmd)
1777 {
1778         int r = -EINVAL;
1779         struct dm_block_manager *old_bm = NULL, *new_bm = NULL;
1780
1781         /* fail_io is double-checked with cmd->root_lock held below */
1782         if (unlikely(cmd->fail_io))
1783                 return r;
1784
1785         /*
1786          * Replacement block manager (new_bm) is created and old_bm destroyed outside of
1787          * cmd root_lock to avoid ABBA deadlock that would result (due to life-cycle of
1788          * shrinker associated with the block manager's bufio client vs cmd root_lock).
1789          * - must take shrinker_mutex without holding cmd->root_lock
1790          */
1791         new_bm = dm_block_manager_create(cmd->bdev, DM_CACHE_METADATA_BLOCK_SIZE << SECTOR_SHIFT,
1792                                          CACHE_MAX_CONCURRENT_LOCKS);
1793
1794         WRITE_LOCK(cmd);
1795         if (cmd->fail_io) {
1796                 WRITE_UNLOCK(cmd);
1797                 goto out;
1798         }
1799
1800         __destroy_persistent_data_objects(cmd, false);
1801         old_bm = cmd->bm;
1802         if (IS_ERR(new_bm)) {
1803                 DMERR("could not create block manager during abort");
1804                 cmd->bm = NULL;
1805                 r = PTR_ERR(new_bm);
1806                 goto out_unlock;
1807         }
1808
1809         cmd->bm = new_bm;
1810         r = __open_or_format_metadata(cmd, false);
1811         if (r) {
1812                 cmd->bm = NULL;
1813                 goto out_unlock;
1814         }
1815         new_bm = NULL;
1816 out_unlock:
1817         if (r)
1818                 cmd->fail_io = true;
1819         WRITE_UNLOCK(cmd);
1820         dm_block_manager_destroy(old_bm);
1821 out:
1822         if (new_bm && !IS_ERR(new_bm))
1823                 dm_block_manager_destroy(new_bm);
1824
1825         return r;
1826 }