drivers/md/dm-clone-metadata.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2019 Arrikto, Inc. All Rights Reserved.
   4  */
   5
   6 #include <linux/mm.h>
   7 #include <linux/err.h>
   8 #include <linux/slab.h>
   9 #include <linux/rwsem.h>
  10 #include <linux/bitops.h>
  11 #include <linux/bitmap.h>
  12 #include <linux/device-mapper.h>
  13
  14 #include "persistent-data/dm-bitset.h"
  15 #include "persistent-data/dm-space-map.h"
  16 #include "persistent-data/dm-block-manager.h"
  17 #include "persistent-data/dm-transaction-manager.h"
  18
  19 #include "dm-clone-metadata.h"
  20
  21 #define DM_MSG_PREFIX "clone metadata"
  22
  23 #define SUPERBLOCK_LOCATION 0
  24 #define SUPERBLOCK_MAGIC 0x8af27f64
  25 #define SUPERBLOCK_CSUM_XOR 257649492
  26
  27 #define DM_CLONE_MAX_CONCURRENT_LOCKS 5
  28
  29 #define UUID_LEN 16
  30
  31 /* Min and max dm-clone metadata versions supported */
  32 #define DM_CLONE_MIN_METADATA_VERSION 1
  33 #define DM_CLONE_MAX_METADATA_VERSION 1
  34
  35 /*
  36  * On-disk metadata layout
  37  */
  38 struct superblock_disk {
  39         __le32 csum;
  40         __le32 flags;
  41         __le64 blocknr;
  42
  43         __u8 uuid[UUID_LEN];
  44         __le64 magic;
  45         __le32 version;
  46
  47         __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
  48
  49         __le64 region_size;
  50         __le64 target_size;
  51
  52         __le64 bitset_root;
  53 } __packed;
  54
  55 /*
  56  * Region and Dirty bitmaps.
  57  *
  58  * dm-clone logically splits the source and destination devices in regions of
  59  * fixed size. The destination device's regions are gradually hydrated, i.e.,
  60  * we copy (clone) the source's regions to the destination device. Eventually,
  61  * all regions will get hydrated and all I/O will be served from the
  62  * destination device.
  63  *
  64  * We maintain an on-disk bitmap which tracks the state of each of the
  65  * destination device's regions, i.e., whether they are hydrated or not.
  66  *
  67  * To save constantly doing look ups on disk we keep an in core copy of the
  68  * on-disk bitmap, the region_map.
  69  *
  70  * In order to track which regions are hydrated during a metadata transaction,
  71  * we use a second set of bitmaps, the dmap (dirty bitmap), which includes two
  72  * bitmaps, namely dirty_regions and dirty_words. The dirty_regions bitmap
  73  * tracks the regions that got hydrated during the current metadata
  74  * transaction. The dirty_words bitmap tracks the dirty words, i.e. longs, of
  75  * the dirty_regions bitmap.
  76  *
  77  * This allows us to precisely track the regions that were hydrated during the
  78  * current metadata transaction and update the metadata accordingly, when we
  79  * commit the current transaction. This is important because dm-clone should
  80  * only commit the metadata of regions that were properly flushed to the
  81  * destination device beforehand. Otherwise, in case of a crash, we could end
  82  * up with a corrupted dm-clone device.
  83  *
  84  * When a region finishes hydrating dm-clone calls
  85  * dm_clone_set_region_hydrated(), or for discard requests
  86  * dm_clone_cond_set_range(), which sets the corresponding bits in region_map
  87  * and dmap.
  88  *
  89  * During a metadata commit we scan dmap->dirty_words and dmap->dirty_regions
  90  * and update the on-disk metadata accordingly. Thus, we don't have to flush to
  91  * disk the whole region_map. We can just flush the dirty region_map bits.
  92  *
  93  * We use the helper dmap->dirty_words bitmap, which is smaller than the
  94  * original region_map, to reduce the amount of memory accesses during a
  95  * metadata commit. Moreover, as dm-bitset also accesses the on-disk bitmap in
  96  * 64-bit word granularity, the dirty_words bitmap helps us avoid useless disk
  97  * accesses.
  98  *
  99  * We could update directly the on-disk bitmap, when dm-clone calls either
 100  * dm_clone_set_region_hydrated() or dm_clone_cond_set_range(), buts this
 101  * inserts significant metadata I/O overhead in dm-clone's I/O path. Also, as
 102  * these two functions don't block, we can call them in interrupt context,
 103  * e.g., in a hooked overwrite bio's completion routine, and further reduce the
 104  * I/O completion latency.
 105  *
 106  * We maintain two dirty bitmap sets. During a metadata commit we atomically
 107  * swap the currently used dmap with the unused one. This allows the metadata
 108  * update functions to run concurrently with an ongoing commit.
 109  */
 110 struct dirty_map {
 111         unsigned long *dirty_words;
 112         unsigned long *dirty_regions;
 113         unsigned int changed;
 114 };
 115
 116 struct dm_clone_metadata {
 117         /* The metadata block device */
 118         struct block_device *bdev;
 119
 120         sector_t target_size;
 121         sector_t region_size;
 122         unsigned long nr_regions;
 123         unsigned long nr_words;
 124
 125         /* Spinlock protecting the region and dirty bitmaps. */
 126         spinlock_t bitmap_lock;
 127         struct dirty_map dmap[2];
 128         struct dirty_map *current_dmap;
 129
 130         /* Protected by lock */
 131         struct dirty_map *committing_dmap;
 132
 133         /*
 134          * In core copy of the on-disk bitmap to save constantly doing look ups
 135          * on disk.
 136          */
 137         unsigned long *region_map;
 138
 139         /* Protected by bitmap_lock */
 140         unsigned int read_only;
 141
 142         struct dm_block_manager *bm;
 143         struct dm_space_map *sm;
 144         struct dm_transaction_manager *tm;
 145
 146         struct rw_semaphore lock;
 147
 148         struct dm_disk_bitset bitset_info;
 149         dm_block_t bitset_root;
 150
 151         /*
 152          * Reading the space map root can fail, so we read it into this
 153          * buffer before the superblock is locked and updated.
 154          */
 155         __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
 156
 157         bool hydration_done:1;
 158         bool fail_io:1;
 159 };
 160
 161 /*---------------------------------------------------------------------------*/
 162
 163 /*
 164  * Superblock validation.
 165  */
 166 static void sb_prepare_for_write(const struct dm_block_validator *v,
 167                                  struct dm_block *b, size_t sb_block_size)
 168 {
 169         struct superblock_disk *sb;
 170         u32 csum;
 171
 172         sb = dm_block_data(b);
 173         sb->blocknr = cpu_to_le64(dm_block_location(b));
 174
 175         csum = dm_bm_checksum(&sb->flags, sb_block_size - sizeof(__le32),
 176                               SUPERBLOCK_CSUM_XOR);
 177         sb->csum = cpu_to_le32(csum);
 178 }
 179
 180 static int sb_check(const struct dm_block_validator *v, struct dm_block *b,
 181                     size_t sb_block_size)
 182 {
 183         struct superblock_disk *sb;
 184         u32 csum, metadata_version;
 185
 186         sb = dm_block_data(b);
 187
 188         if (dm_block_location(b) != le64_to_cpu(sb->blocknr)) {
 189                 DMERR("Superblock check failed: blocknr %llu, expected %llu",
 190                       le64_to_cpu(sb->blocknr),
 191                       (unsigned long long)dm_block_location(b));
 192                 return -ENOTBLK;
 193         }
 194
 195         if (le64_to_cpu(sb->magic) != SUPERBLOCK_MAGIC) {
 196                 DMERR("Superblock check failed: magic %llu, expected %llu",
 197                       le64_to_cpu(sb->magic),
 198                       (unsigned long long)SUPERBLOCK_MAGIC);
 199                 return -EILSEQ;
 200         }
 201
 202         csum = dm_bm_checksum(&sb->flags, sb_block_size - sizeof(__le32),
 203                               SUPERBLOCK_CSUM_XOR);
 204         if (sb->csum != cpu_to_le32(csum)) {
 205                 DMERR("Superblock check failed: checksum %u, expected %u",
 206                       csum, le32_to_cpu(sb->csum));
 207                 return -EILSEQ;
 208         }
 209
 210         /* Check metadata version */
 211         metadata_version = le32_to_cpu(sb->version);
 212         if (metadata_version < DM_CLONE_MIN_METADATA_VERSION ||
 213             metadata_version > DM_CLONE_MAX_METADATA_VERSION) {
 214                 DMERR("Clone metadata version %u found, but only versions between %u and %u supported.",
 215                       metadata_version, DM_CLONE_MIN_METADATA_VERSION,
 216                       DM_CLONE_MAX_METADATA_VERSION);
 217                 return -EINVAL;
 218         }
 219
 220         return 0;
 221 }
 222
 223 static const struct dm_block_validator sb_validator = {
 224         .name = "superblock",
 225         .prepare_for_write = sb_prepare_for_write,
 226         .check = sb_check
 227 };
 228
 229 /*
 230  * Check if the superblock is formatted or not. We consider the superblock to
 231  * be formatted in case we find non-zero bytes in it.
 232  */
 233 static int __superblock_all_zeroes(struct dm_block_manager *bm, bool *formatted)
 234 {
 235         int r;
 236         unsigned int i, nr_words;
 237         struct dm_block *sblock;
 238         __le64 *data_le, zero = cpu_to_le64(0);
 239
 240         /*
 241          * We don't use a validator here because the superblock could be all
 242          * zeroes.
 243          */
 244         r = dm_bm_read_lock(bm, SUPERBLOCK_LOCATION, NULL, &sblock);
 245         if (r) {
 246                 DMERR("Failed to read_lock superblock");
 247                 return r;
 248         }
 249
 250         data_le = dm_block_data(sblock);
 251         *formatted = false;
 252
 253         /* This assumes that the block size is a multiple of 8 bytes */
 254         BUG_ON(dm_bm_block_size(bm) % sizeof(__le64));
 255         nr_words = dm_bm_block_size(bm) / sizeof(__le64);
 256         for (i = 0; i < nr_words; i++) {
 257                 if (data_le[i] != zero) {
 258                         *formatted = true;
 259                         break;
 260                 }
 261         }
 262
 263         dm_bm_unlock(sblock);
 264
 265         return 0;
 266 }
 267
 268 /*---------------------------------------------------------------------------*/
 269
 270 /*
 271  * Low-level metadata handling.
 272  */
 273 static inline int superblock_read_lock(struct dm_clone_metadata *cmd,
 274                                        struct dm_block **sblock)
 275 {
 276         return dm_bm_read_lock(cmd->bm, SUPERBLOCK_LOCATION, &sb_validator, sblock);
 277 }
 278
 279 static inline int superblock_write_lock_zero(struct dm_clone_metadata *cmd,
 280                                              struct dm_block **sblock)
 281 {
 282         return dm_bm_write_lock_zero(cmd->bm, SUPERBLOCK_LOCATION, &sb_validator, sblock);
 283 }
 284
 285 static int __copy_sm_root(struct dm_clone_metadata *cmd)
 286 {
 287         int r;
 288         size_t root_size;
 289
 290         r = dm_sm_root_size(cmd->sm, &root_size);
 291         if (r)
 292                 return r;
 293
 294         return dm_sm_copy_root(cmd->sm, &cmd->metadata_space_map_root, root_size);
 295 }
 296
 297 /* Save dm-clone metadata in superblock */
 298 static void __prepare_superblock(struct dm_clone_metadata *cmd,
 299                                  struct superblock_disk *sb)
 300 {
 301         sb->flags = cpu_to_le32(0UL);
 302
 303         /* FIXME: UUID is currently unused */
 304         memset(sb->uuid, 0, sizeof(sb->uuid));
 305
 306         sb->magic = cpu_to_le64(SUPERBLOCK_MAGIC);
 307         sb->version = cpu_to_le32(DM_CLONE_MAX_METADATA_VERSION);
 308
 309         /* Save the metadata space_map root */
 310         memcpy(&sb->metadata_space_map_root, &cmd->metadata_space_map_root,
 311                sizeof(cmd->metadata_space_map_root));
 312
 313         sb->region_size = cpu_to_le64(cmd->region_size);
 314         sb->target_size = cpu_to_le64(cmd->target_size);
 315         sb->bitset_root = cpu_to_le64(cmd->bitset_root);
 316 }
 317
 318 static int __open_metadata(struct dm_clone_metadata *cmd)
 319 {
 320         int r;
 321         struct dm_block *sblock;
 322         struct superblock_disk *sb;
 323
 324         r = superblock_read_lock(cmd, &sblock);
 325
 326         if (r) {
 327                 DMERR("Failed to read_lock superblock");
 328                 return r;
 329         }
 330
 331         sb = dm_block_data(sblock);
 332
 333         /* Verify that target_size and region_size haven't changed. */
 334         if (cmd->region_size != le64_to_cpu(sb->region_size) ||
 335             cmd->target_size != le64_to_cpu(sb->target_size)) {
 336                 DMERR("Region and/or target size don't match the ones in metadata");
 337                 r = -EINVAL;
 338                 goto out_with_lock;
 339         }
 340
 341         r = dm_tm_open_with_sm(cmd->bm, SUPERBLOCK_LOCATION,
 342                                sb->metadata_space_map_root,
 343                                sizeof(sb->metadata_space_map_root),
 344                                &cmd->tm, &cmd->sm);
 345
 346         if (r) {
 347                 DMERR("dm_tm_open_with_sm failed");
 348                 goto out_with_lock;
 349         }
 350
 351         dm_disk_bitset_init(cmd->tm, &cmd->bitset_info);
 352         cmd->bitset_root = le64_to_cpu(sb->bitset_root);
 353
 354 out_with_lock:
 355         dm_bm_unlock(sblock);
 356
 357         return r;
 358 }
 359
 360 static int __format_metadata(struct dm_clone_metadata *cmd)
 361 {
 362         int r;
 363         struct dm_block *sblock;
 364         struct superblock_disk *sb;
 365
 366         r = dm_tm_create_with_sm(cmd->bm, SUPERBLOCK_LOCATION, &cmd->tm, &cmd->sm);
 367         if (r) {
 368                 DMERR("Failed to create transaction manager");
 369                 return r;
 370         }
 371
 372         dm_disk_bitset_init(cmd->tm, &cmd->bitset_info);
 373
 374         r = dm_bitset_empty(&cmd->bitset_info, &cmd->bitset_root);
 375         if (r) {
 376                 DMERR("Failed to create empty on-disk bitset");
 377                 goto err_with_tm;
 378         }
 379
 380         r = dm_bitset_resize(&cmd->bitset_info, cmd->bitset_root, 0,
 381                              cmd->nr_regions, false, &cmd->bitset_root);
 382         if (r) {
 383                 DMERR("Failed to resize on-disk bitset to %lu entries", cmd->nr_regions);
 384                 goto err_with_tm;
 385         }
 386
 387         /* Flush to disk all blocks, except the superblock */
 388         r = dm_tm_pre_commit(cmd->tm);
 389         if (r) {
 390                 DMERR("dm_tm_pre_commit failed");
 391                 goto err_with_tm;
 392         }
 393
 394         r = __copy_sm_root(cmd);
 395         if (r) {
 396                 DMERR("__copy_sm_root failed");
 397                 goto err_with_tm;
 398         }
 399
 400         r = superblock_write_lock_zero(cmd, &sblock);
 401         if (r) {
 402                 DMERR("Failed to write_lock superblock");
 403                 goto err_with_tm;
 404         }
 405
 406         sb = dm_block_data(sblock);
 407         __prepare_superblock(cmd, sb);
 408         r = dm_tm_commit(cmd->tm, sblock);
 409         if (r) {
 410                 DMERR("Failed to commit superblock");
 411                 goto err_with_tm;
 412         }
 413
 414         return 0;
 415
 416 err_with_tm:
 417         dm_sm_destroy(cmd->sm);
 418         dm_tm_destroy(cmd->tm);
 419
 420         return r;
 421 }
 422
 423 static int __open_or_format_metadata(struct dm_clone_metadata *cmd, bool may_format_device)
 424 {
 425         int r;
 426         bool formatted = false;
 427
 428         r = __superblock_all_zeroes(cmd->bm, &formatted);
 429         if (r)
 430                 return r;
 431
 432         if (!formatted)
 433                 return may_format_device ? __format_metadata(cmd) : -EPERM;
 434
 435         return __open_metadata(cmd);
 436 }
 437
 438 static int __create_persistent_data_structures(struct dm_clone_metadata *cmd,
 439                                                bool may_format_device)
 440 {
 441         int r;
 442
 443         /* Create block manager */
 444         cmd->bm = dm_block_manager_create(cmd->bdev,
 445                                          DM_CLONE_METADATA_BLOCK_SIZE << SECTOR_SHIFT,
 446                                          DM_CLONE_MAX_CONCURRENT_LOCKS);
 447         if (IS_ERR(cmd->bm)) {
 448                 DMERR("Failed to create block manager");
 449                 return PTR_ERR(cmd->bm);
 450         }
 451
 452         r = __open_or_format_metadata(cmd, may_format_device);
 453         if (r)
 454                 dm_block_manager_destroy(cmd->bm);
 455
 456         return r;
 457 }
 458
 459 static void __destroy_persistent_data_structures(struct dm_clone_metadata *cmd)
 460 {
 461         dm_sm_destroy(cmd->sm);
 462         dm_tm_destroy(cmd->tm);
 463         dm_block_manager_destroy(cmd->bm);
 464 }
 465
 466 /*---------------------------------------------------------------------------*/
 467
 468 static int __dirty_map_init(struct dirty_map *dmap, unsigned long nr_words,
 469                             unsigned long nr_regions)
 470 {
 471         dmap->changed = 0;
 472
 473         dmap->dirty_words = kvzalloc(bitmap_size(nr_words), GFP_KERNEL);
 474         if (!dmap->dirty_words)
 475                 return -ENOMEM;
 476
 477         dmap->dirty_regions = kvzalloc(bitmap_size(nr_regions), GFP_KERNEL);
 478         if (!dmap->dirty_regions) {
 479                 kvfree(dmap->dirty_words);
 480                 return -ENOMEM;
 481         }
 482
 483         return 0;
 484 }
 485
 486 static void __dirty_map_exit(struct dirty_map *dmap)
 487 {
 488         kvfree(dmap->dirty_words);
 489         kvfree(dmap->dirty_regions);
 490 }
 491
 492 static int dirty_map_init(struct dm_clone_metadata *cmd)
 493 {
 494         if (__dirty_map_init(&cmd->dmap[0], cmd->nr_words, cmd->nr_regions)) {
 495                 DMERR("Failed to allocate dirty bitmap");
 496                 return -ENOMEM;
 497         }
 498
 499         if (__dirty_map_init(&cmd->dmap[1], cmd->nr_words, cmd->nr_regions)) {
 500                 DMERR("Failed to allocate dirty bitmap");
 501                 __dirty_map_exit(&cmd->dmap[0]);
 502                 return -ENOMEM;
 503         }
 504
 505         cmd->current_dmap = &cmd->dmap[0];
 506         cmd->committing_dmap = NULL;
 507
 508         return 0;
 509 }
 510
 511 static void dirty_map_exit(struct dm_clone_metadata *cmd)
 512 {
 513         __dirty_map_exit(&cmd->dmap[0]);
 514         __dirty_map_exit(&cmd->dmap[1]);
 515 }
 516
 517 static int __load_bitset_in_core(struct dm_clone_metadata *cmd)
 518 {
 519         int r;
 520         unsigned long i;
 521         struct dm_bitset_cursor c;
 522
 523         /* Flush bitset cache */
 524         r = dm_bitset_flush(&cmd->bitset_info, cmd->bitset_root, &cmd->bitset_root);
 525         if (r)
 526                 return r;
 527
 528         r = dm_bitset_cursor_begin(&cmd->bitset_info, cmd->bitset_root, cmd->nr_regions, &c);
 529         if (r)
 530                 return r;
 531
 532         for (i = 0; ; i++) {
 533                 __assign_bit(i, cmd->region_map, dm_bitset_cursor_get_value(&c));
 534
 535                 if (i >= (cmd->nr_regions - 1))
 536                         break;
 537
 538                 r = dm_bitset_cursor_next(&c);
 539
 540                 if (r)
 541                         break;
 542         }
 543
 544         dm_bitset_cursor_end(&c);
 545
 546         return r;
 547 }
 548
 549 struct dm_clone_metadata *dm_clone_metadata_open(struct block_device *bdev,
 550                                                  sector_t target_size,
 551                                                  sector_t region_size)
 552 {
 553         int r;
 554         struct dm_clone_metadata *cmd;
 555
 556         cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
 557         if (!cmd) {
 558                 DMERR("Failed to allocate memory for dm-clone metadata");
 559                 return ERR_PTR(-ENOMEM);
 560         }
 561
 562         cmd->bdev = bdev;
 563         cmd->target_size = target_size;
 564         cmd->region_size = region_size;
 565         cmd->nr_regions = dm_sector_div_up(cmd->target_size, cmd->region_size);
 566         cmd->nr_words = BITS_TO_LONGS(cmd->nr_regions);
 567
 568         init_rwsem(&cmd->lock);
 569         spin_lock_init(&cmd->bitmap_lock);
 570         cmd->read_only = 0;
 571         cmd->fail_io = false;
 572         cmd->hydration_done = false;
 573
 574         cmd->region_map = kvmalloc(bitmap_size(cmd->nr_regions), GFP_KERNEL);
 575         if (!cmd->region_map) {
 576                 DMERR("Failed to allocate memory for region bitmap");
 577                 r = -ENOMEM;
 578                 goto out_with_md;
 579         }
 580
 581         r = __create_persistent_data_structures(cmd, true);
 582         if (r)
 583                 goto out_with_region_map;
 584
 585         r = __load_bitset_in_core(cmd);
 586         if (r) {
 587                 DMERR("Failed to load on-disk region map");
 588                 goto out_with_pds;
 589         }
 590
 591         r = dirty_map_init(cmd);
 592         if (r)
 593                 goto out_with_pds;
 594
 595         if (bitmap_full(cmd->region_map, cmd->nr_regions))
 596                 cmd->hydration_done = true;
 597
 598         return cmd;
 599
 600 out_with_pds:
 601         __destroy_persistent_data_structures(cmd);
 602
 603 out_with_region_map:
 604         kvfree(cmd->region_map);
 605
 606 out_with_md:
 607         kfree(cmd);
 608
 609         return ERR_PTR(r);
 610 }
 611
 612 void dm_clone_metadata_close(struct dm_clone_metadata *cmd)
 613 {
 614         if (!cmd->fail_io)
 615                 __destroy_persistent_data_structures(cmd);
 616
 617         dirty_map_exit(cmd);
 618         kvfree(cmd->region_map);
 619         kfree(cmd);
 620 }
 621
 622 bool dm_clone_is_hydration_done(struct dm_clone_metadata *cmd)
 623 {
 624         return cmd->hydration_done;
 625 }
 626
 627 bool dm_clone_is_region_hydrated(struct dm_clone_metadata *cmd, unsigned long region_nr)
 628 {
 629         return dm_clone_is_hydration_done(cmd) || test_bit(region_nr, cmd->region_map);
 630 }
 631
 632 bool dm_clone_is_range_hydrated(struct dm_clone_metadata *cmd,
 633                                 unsigned long start, unsigned long nr_regions)
 634 {
 635         unsigned long bit;
 636
 637         if (dm_clone_is_hydration_done(cmd))
 638                 return true;
 639
 640         bit = find_next_zero_bit(cmd->region_map, cmd->nr_regions, start);
 641
 642         return (bit >= (start + nr_regions));
 643 }
 644
 645 unsigned int dm_clone_nr_of_hydrated_regions(struct dm_clone_metadata *cmd)
 646 {
 647         return bitmap_weight(cmd->region_map, cmd->nr_regions);
 648 }
 649
 650 unsigned long dm_clone_find_next_unhydrated_region(struct dm_clone_metadata *cmd,
 651                                                    unsigned long start)
 652 {
 653         return find_next_zero_bit(cmd->region_map, cmd->nr_regions, start);
 654 }
 655
 656 static int __update_metadata_word(struct dm_clone_metadata *cmd,
 657                                   unsigned long *dirty_regions,
 658                                   unsigned long word)
 659 {
 660         int r;
 661         unsigned long index = word * BITS_PER_LONG;
 662         unsigned long max_index = min(cmd->nr_regions, (word + 1) * BITS_PER_LONG);
 663
 664         while (index < max_index) {
 665                 if (test_bit(index, dirty_regions)) {
 666                         r = dm_bitset_set_bit(&cmd->bitset_info, cmd->bitset_root,
 667                                               index, &cmd->bitset_root);
 668                         if (r) {
 669                                 DMERR("dm_bitset_set_bit failed");
 670                                 return r;
 671                         }
 672                         __clear_bit(index, dirty_regions);
 673                 }
 674                 index++;
 675         }
 676
 677         return 0;
 678 }
 679
 680 static int __metadata_commit(struct dm_clone_metadata *cmd)
 681 {
 682         int r;
 683         struct dm_block *sblock;
 684         struct superblock_disk *sb;
 685
 686         /* Flush bitset cache */
 687         r = dm_bitset_flush(&cmd->bitset_info, cmd->bitset_root, &cmd->bitset_root);
 688         if (r) {
 689                 DMERR("dm_bitset_flush failed");
 690                 return r;
 691         }
 692
 693         /* Flush to disk all blocks, except the superblock */
 694         r = dm_tm_pre_commit(cmd->tm);
 695         if (r) {
 696                 DMERR("dm_tm_pre_commit failed");
 697                 return r;
 698         }
 699
 700         /* Save the space map root in cmd->metadata_space_map_root */
 701         r = __copy_sm_root(cmd);
 702         if (r) {
 703                 DMERR("__copy_sm_root failed");
 704                 return r;
 705         }
 706
 707         /* Lock the superblock */
 708         r = superblock_write_lock_zero(cmd, &sblock);
 709         if (r) {
 710                 DMERR("Failed to write_lock superblock");
 711                 return r;
 712         }
 713
 714         /* Save the metadata in superblock */
 715         sb = dm_block_data(sblock);
 716         __prepare_superblock(cmd, sb);
 717
 718         /* Unlock superblock and commit it to disk */
 719         r = dm_tm_commit(cmd->tm, sblock);
 720         if (r) {
 721                 DMERR("Failed to commit superblock");
 722                 return r;
 723         }
 724
 725         /*
 726          * FIXME: Find a more efficient way to check if the hydration is done.
 727          */
 728         if (bitmap_full(cmd->region_map, cmd->nr_regions))
 729                 cmd->hydration_done = true;
 730
 731         return 0;
 732 }
 733
 734 static int __flush_dmap(struct dm_clone_metadata *cmd, struct dirty_map *dmap)
 735 {
 736         int r;
 737         unsigned long word;
 738
 739         word = 0;
 740         do {
 741                 word = find_next_bit(dmap->dirty_words, cmd->nr_words, word);
 742
 743                 if (word == cmd->nr_words)
 744                         break;
 745
 746                 r = __update_metadata_word(cmd, dmap->dirty_regions, word);
 747
 748                 if (r)
 749                         return r;
 750
 751                 __clear_bit(word, dmap->dirty_words);
 752                 word++;
 753         } while (word < cmd->nr_words);
 754
 755         r = __metadata_commit(cmd);
 756
 757         if (r)
 758                 return r;
 759
 760         /* Update the changed flag */
 761         spin_lock_irq(&cmd->bitmap_lock);
 762         dmap->changed = 0;
 763         spin_unlock_irq(&cmd->bitmap_lock);
 764
 765         return 0;
 766 }
 767
 768 int dm_clone_metadata_pre_commit(struct dm_clone_metadata *cmd)
 769 {
 770         int r = 0;
 771         struct dirty_map *dmap, *next_dmap;
 772
 773         down_write(&cmd->lock);
 774
 775         if (cmd->fail_io || dm_bm_is_read_only(cmd->bm)) {
 776                 r = -EPERM;
 777                 goto out;
 778         }
 779
 780         /* Get current dirty bitmap */
 781         dmap = cmd->current_dmap;
 782
 783         /* Get next dirty bitmap */
 784         next_dmap = (dmap == &cmd->dmap[0]) ? &cmd->dmap[1] : &cmd->dmap[0];
 785
 786         /*
 787          * The last commit failed, so we don't have a clean dirty-bitmap to
 788          * use.
 789          */
 790         if (WARN_ON(next_dmap->changed || cmd->committing_dmap)) {
 791                 r = -EINVAL;
 792                 goto out;
 793         }
 794
 795         /* Swap dirty bitmaps */
 796         spin_lock_irq(&cmd->bitmap_lock);
 797         cmd->current_dmap = next_dmap;
 798         spin_unlock_irq(&cmd->bitmap_lock);
 799
 800         /* Set old dirty bitmap as currently committing */
 801         cmd->committing_dmap = dmap;
 802 out:
 803         up_write(&cmd->lock);
 804
 805         return r;
 806 }
 807
 808 int dm_clone_metadata_commit(struct dm_clone_metadata *cmd)
 809 {
 810         int r = -EPERM;
 811
 812         down_write(&cmd->lock);
 813
 814         if (cmd->fail_io || dm_bm_is_read_only(cmd->bm))
 815                 goto out;
 816
 817         if (WARN_ON(!cmd->committing_dmap)) {
 818                 r = -EINVAL;
 819                 goto out;
 820         }
 821
 822         r = __flush_dmap(cmd, cmd->committing_dmap);
 823         if (!r) {
 824                 /* Clear committing dmap */
 825                 cmd->committing_dmap = NULL;
 826         }
 827 out:
 828         up_write(&cmd->lock);
 829
 830         return r;
 831 }
 832
 833 int dm_clone_set_region_hydrated(struct dm_clone_metadata *cmd, unsigned long region_nr)
 834 {
 835         int r = 0;
 836         struct dirty_map *dmap;
 837         unsigned long word, flags;
 838
 839         if (unlikely(region_nr >= cmd->nr_regions)) {
 840                 DMERR("Region %lu out of range (total number of regions %lu)",
 841                       region_nr, cmd->nr_regions);
 842                 return -ERANGE;
 843         }
 844
 845         word = region_nr / BITS_PER_LONG;
 846
 847         spin_lock_irqsave(&cmd->bitmap_lock, flags);
 848
 849         if (cmd->read_only) {
 850                 r = -EPERM;
 851                 goto out;
 852         }
 853
 854         dmap = cmd->current_dmap;
 855
 856         __set_bit(word, dmap->dirty_words);
 857         __set_bit(region_nr, dmap->dirty_regions);
 858         __set_bit(region_nr, cmd->region_map);
 859         dmap->changed = 1;
 860
 861 out:
 862         spin_unlock_irqrestore(&cmd->bitmap_lock, flags);
 863
 864         return r;
 865 }
 866
 867 int dm_clone_cond_set_range(struct dm_clone_metadata *cmd, unsigned long start,
 868                             unsigned long nr_regions)
 869 {
 870         int r = 0;
 871         struct dirty_map *dmap;
 872         unsigned long word, region_nr;
 873
 874         if (unlikely(start >= cmd->nr_regions || (start + nr_regions) < start ||
 875                      (start + nr_regions) > cmd->nr_regions)) {
 876                 DMERR("Invalid region range: start %lu, nr_regions %lu (total number of regions %lu)",
 877                       start, nr_regions, cmd->nr_regions);
 878                 return -ERANGE;
 879         }
 880
 881         spin_lock_irq(&cmd->bitmap_lock);
 882
 883         if (cmd->read_only) {
 884                 r = -EPERM;
 885                 goto out;
 886         }
 887
 888         dmap = cmd->current_dmap;
 889         for (region_nr = start; region_nr < (start + nr_regions); region_nr++) {
 890                 if (!test_bit(region_nr, cmd->region_map)) {
 891                         word = region_nr / BITS_PER_LONG;
 892                         __set_bit(word, dmap->dirty_words);
 893                         __set_bit(region_nr, dmap->dirty_regions);
 894                         __set_bit(region_nr, cmd->region_map);
 895                         dmap->changed = 1;
 896                 }
 897         }
 898 out:
 899         spin_unlock_irq(&cmd->bitmap_lock);
 900
 901         return r;
 902 }
 903
 904 /*
 905  * WARNING: This must not be called concurrently with either
 906  * dm_clone_set_region_hydrated() or dm_clone_cond_set_range(), as it changes
 907  * cmd->region_map without taking the cmd->bitmap_lock spinlock. The only
 908  * exception is after setting the metadata to read-only mode, using
 909  * dm_clone_metadata_set_read_only().
 910  *
 911  * We don't take the spinlock because __load_bitset_in_core() does I/O, so it
 912  * may block.
 913  */
 914 int dm_clone_reload_in_core_bitset(struct dm_clone_metadata *cmd)
 915 {
 916         int r = -EINVAL;
 917
 918         down_write(&cmd->lock);
 919
 920         if (cmd->fail_io)
 921                 goto out;
 922
 923         r = __load_bitset_in_core(cmd);
 924 out:
 925         up_write(&cmd->lock);
 926
 927         return r;
 928 }
 929
 930 bool dm_clone_changed_this_transaction(struct dm_clone_metadata *cmd)
 931 {
 932         bool r;
 933         unsigned long flags;
 934
 935         spin_lock_irqsave(&cmd->bitmap_lock, flags);
 936         r = cmd->dmap[0].changed || cmd->dmap[1].changed;
 937         spin_unlock_irqrestore(&cmd->bitmap_lock, flags);
 938
 939         return r;
 940 }
 941
 942 int dm_clone_metadata_abort(struct dm_clone_metadata *cmd)
 943 {
 944         int r = -EPERM;
 945
 946         down_write(&cmd->lock);
 947
 948         if (cmd->fail_io || dm_bm_is_read_only(cmd->bm))
 949                 goto out;
 950
 951         __destroy_persistent_data_structures(cmd);
 952
 953         r = __create_persistent_data_structures(cmd, false);
 954         if (r) {
 955                 /* If something went wrong we can neither write nor read the metadata */
 956                 cmd->fail_io = true;
 957         }
 958 out:
 959         up_write(&cmd->lock);
 960
 961         return r;
 962 }
 963
 964 void dm_clone_metadata_set_read_only(struct dm_clone_metadata *cmd)
 965 {
 966         down_write(&cmd->lock);
 967
 968         spin_lock_irq(&cmd->bitmap_lock);
 969         cmd->read_only = 1;
 970         spin_unlock_irq(&cmd->bitmap_lock);
 971
 972         if (!cmd->fail_io)
 973                 dm_bm_set_read_only(cmd->bm);
 974
 975         up_write(&cmd->lock);
 976 }
 977
 978 void dm_clone_metadata_set_read_write(struct dm_clone_metadata *cmd)
 979 {
 980         down_write(&cmd->lock);
 981
 982         spin_lock_irq(&cmd->bitmap_lock);
 983         cmd->read_only = 0;
 984         spin_unlock_irq(&cmd->bitmap_lock);
 985
 986         if (!cmd->fail_io)
 987                 dm_bm_set_read_write(cmd->bm);
 988
 989         up_write(&cmd->lock);
 990 }
 991
 992 int dm_clone_get_free_metadata_block_count(struct dm_clone_metadata *cmd,
 993                                            dm_block_t *result)
 994 {
 995         int r = -EINVAL;
 996
 997         down_read(&cmd->lock);
 998
 999         if (!cmd->fail_io)
1000                 r = dm_sm_get_nr_free(cmd->sm, result);
1001
1002         up_read(&cmd->lock);
1003
1004         return r;
1005 }
1006
1007 int dm_clone_get_metadata_dev_size(struct dm_clone_metadata *cmd,
1008                                    dm_block_t *result)
1009 {
1010         int r = -EINVAL;
1011
1012         down_read(&cmd->lock);
1013
1014         if (!cmd->fail_io)
1015                 r = dm_sm_get_nr_blocks(cmd->sm, result);
1016
1017         up_read(&cmd->lock);
1018
1019         return r;
1020 }