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(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(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 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 size_t bitmap_size(unsigned long nr_bits)
 469 {
 470         return BITS_TO_LONGS(nr_bits) * sizeof(long);
 471 }
 472
 473 static int __dirty_map_init(struct dirty_map *dmap, unsigned long nr_words,
 474                             unsigned long nr_regions)
 475 {
 476         dmap->changed = 0;
 477
 478         dmap->dirty_words = kvzalloc(bitmap_size(nr_words), GFP_KERNEL);
 479         if (!dmap->dirty_words)
 480                 return -ENOMEM;
 481
 482         dmap->dirty_regions = kvzalloc(bitmap_size(nr_regions), GFP_KERNEL);
 483         if (!dmap->dirty_regions) {
 484                 kvfree(dmap->dirty_words);
 485                 return -ENOMEM;
 486         }
 487
 488         return 0;
 489 }
 490
 491 static void __dirty_map_exit(struct dirty_map *dmap)
 492 {
 493         kvfree(dmap->dirty_words);
 494         kvfree(dmap->dirty_regions);
 495 }
 496
 497 static int dirty_map_init(struct dm_clone_metadata *cmd)
 498 {
 499         if (__dirty_map_init(&cmd->dmap[0], cmd->nr_words, cmd->nr_regions)) {
 500                 DMERR("Failed to allocate dirty bitmap");
 501                 return -ENOMEM;
 502         }
 503
 504         if (__dirty_map_init(&cmd->dmap[1], cmd->nr_words, cmd->nr_regions)) {
 505                 DMERR("Failed to allocate dirty bitmap");
 506                 __dirty_map_exit(&cmd->dmap[0]);
 507                 return -ENOMEM;
 508         }
 509
 510         cmd->current_dmap = &cmd->dmap[0];
 511         cmd->committing_dmap = NULL;
 512
 513         return 0;
 514 }
 515
 516 static void dirty_map_exit(struct dm_clone_metadata *cmd)
 517 {
 518         __dirty_map_exit(&cmd->dmap[0]);
 519         __dirty_map_exit(&cmd->dmap[1]);
 520 }
 521
 522 static int __load_bitset_in_core(struct dm_clone_metadata *cmd)
 523 {
 524         int r;
 525         unsigned long i;
 526         struct dm_bitset_cursor c;
 527
 528         /* Flush bitset cache */
 529         r = dm_bitset_flush(&cmd->bitset_info, cmd->bitset_root, &cmd->bitset_root);
 530         if (r)
 531                 return r;
 532
 533         r = dm_bitset_cursor_begin(&cmd->bitset_info, cmd->bitset_root, cmd->nr_regions, &c);
 534         if (r)
 535                 return r;
 536
 537         for (i = 0; ; i++) {
 538                 if (dm_bitset_cursor_get_value(&c))
 539                         __set_bit(i, cmd->region_map);
 540                 else
 541                         __clear_bit(i, cmd->region_map);
 542
 543                 if (i >= (cmd->nr_regions - 1))
 544                         break;
 545
 546                 r = dm_bitset_cursor_next(&c);
 547
 548                 if (r)
 549                         break;
 550         }
 551
 552         dm_bitset_cursor_end(&c);
 553
 554         return r;
 555 }
 556
 557 struct dm_clone_metadata *dm_clone_metadata_open(struct block_device *bdev,
 558                                                  sector_t target_size,
 559                                                  sector_t region_size)
 560 {
 561         int r;
 562         struct dm_clone_metadata *cmd;
 563
 564         cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
 565         if (!cmd) {
 566                 DMERR("Failed to allocate memory for dm-clone metadata");
 567                 return ERR_PTR(-ENOMEM);
 568         }
 569
 570         cmd->bdev = bdev;
 571         cmd->target_size = target_size;
 572         cmd->region_size = region_size;
 573         cmd->nr_regions = dm_sector_div_up(cmd->target_size, cmd->region_size);
 574         cmd->nr_words = BITS_TO_LONGS(cmd->nr_regions);
 575
 576         init_rwsem(&cmd->lock);
 577         spin_lock_init(&cmd->bitmap_lock);
 578         cmd->read_only = 0;
 579         cmd->fail_io = false;
 580         cmd->hydration_done = false;
 581
 582         cmd->region_map = kvmalloc(bitmap_size(cmd->nr_regions), GFP_KERNEL);
 583         if (!cmd->region_map) {
 584                 DMERR("Failed to allocate memory for region bitmap");
 585                 r = -ENOMEM;
 586                 goto out_with_md;
 587         }
 588
 589         r = __create_persistent_data_structures(cmd, true);
 590         if (r)
 591                 goto out_with_region_map;
 592
 593         r = __load_bitset_in_core(cmd);
 594         if (r) {
 595                 DMERR("Failed to load on-disk region map");
 596                 goto out_with_pds;
 597         }
 598
 599         r = dirty_map_init(cmd);
 600         if (r)
 601                 goto out_with_pds;
 602
 603         if (bitmap_full(cmd->region_map, cmd->nr_regions))
 604                 cmd->hydration_done = true;
 605
 606         return cmd;
 607
 608 out_with_pds:
 609         __destroy_persistent_data_structures(cmd);
 610
 611 out_with_region_map:
 612         kvfree(cmd->region_map);
 613
 614 out_with_md:
 615         kfree(cmd);
 616
 617         return ERR_PTR(r);
 618 }
 619
 620 void dm_clone_metadata_close(struct dm_clone_metadata *cmd)
 621 {
 622         if (!cmd->fail_io)
 623                 __destroy_persistent_data_structures(cmd);
 624
 625         dirty_map_exit(cmd);
 626         kvfree(cmd->region_map);
 627         kfree(cmd);
 628 }
 629
 630 bool dm_clone_is_hydration_done(struct dm_clone_metadata *cmd)
 631 {
 632         return cmd->hydration_done;
 633 }
 634
 635 bool dm_clone_is_region_hydrated(struct dm_clone_metadata *cmd, unsigned long region_nr)
 636 {
 637         return dm_clone_is_hydration_done(cmd) || test_bit(region_nr, cmd->region_map);
 638 }
 639
 640 bool dm_clone_is_range_hydrated(struct dm_clone_metadata *cmd,
 641                                 unsigned long start, unsigned long nr_regions)
 642 {
 643         unsigned long bit;
 644
 645         if (dm_clone_is_hydration_done(cmd))
 646                 return true;
 647
 648         bit = find_next_zero_bit(cmd->region_map, cmd->nr_regions, start);
 649
 650         return (bit >= (start + nr_regions));
 651 }
 652
 653 unsigned int dm_clone_nr_of_hydrated_regions(struct dm_clone_metadata *cmd)
 654 {
 655         return bitmap_weight(cmd->region_map, cmd->nr_regions);
 656 }
 657
 658 unsigned long dm_clone_find_next_unhydrated_region(struct dm_clone_metadata *cmd,
 659                                                    unsigned long start)
 660 {
 661         return find_next_zero_bit(cmd->region_map, cmd->nr_regions, start);
 662 }
 663
 664 static int __update_metadata_word(struct dm_clone_metadata *cmd,
 665                                   unsigned long *dirty_regions,
 666                                   unsigned long word)
 667 {
 668         int r;
 669         unsigned long index = word * BITS_PER_LONG;
 670         unsigned long max_index = min(cmd->nr_regions, (word + 1) * BITS_PER_LONG);
 671
 672         while (index < max_index) {
 673                 if (test_bit(index, dirty_regions)) {
 674                         r = dm_bitset_set_bit(&cmd->bitset_info, cmd->bitset_root,
 675                                               index, &cmd->bitset_root);
 676                         if (r) {
 677                                 DMERR("dm_bitset_set_bit failed");
 678                                 return r;
 679                         }
 680                         __clear_bit(index, dirty_regions);
 681                 }
 682                 index++;
 683         }
 684
 685         return 0;
 686 }
 687
 688 static int __metadata_commit(struct dm_clone_metadata *cmd)
 689 {
 690         int r;
 691         struct dm_block *sblock;
 692         struct superblock_disk *sb;
 693
 694         /* Flush bitset cache */
 695         r = dm_bitset_flush(&cmd->bitset_info, cmd->bitset_root, &cmd->bitset_root);
 696         if (r) {
 697                 DMERR("dm_bitset_flush failed");
 698                 return r;
 699         }
 700
 701         /* Flush to disk all blocks, except the superblock */
 702         r = dm_tm_pre_commit(cmd->tm);
 703         if (r) {
 704                 DMERR("dm_tm_pre_commit failed");
 705                 return r;
 706         }
 707
 708         /* Save the space map root in cmd->metadata_space_map_root */
 709         r = __copy_sm_root(cmd);
 710         if (r) {
 711                 DMERR("__copy_sm_root failed");
 712                 return r;
 713         }
 714
 715         /* Lock the superblock */
 716         r = superblock_write_lock_zero(cmd, &sblock);
 717         if (r) {
 718                 DMERR("Failed to write_lock superblock");
 719                 return r;
 720         }
 721
 722         /* Save the metadata in superblock */
 723         sb = dm_block_data(sblock);
 724         __prepare_superblock(cmd, sb);
 725
 726         /* Unlock superblock and commit it to disk */
 727         r = dm_tm_commit(cmd->tm, sblock);
 728         if (r) {
 729                 DMERR("Failed to commit superblock");
 730                 return r;
 731         }
 732
 733         /*
 734          * FIXME: Find a more efficient way to check if the hydration is done.
 735          */
 736         if (bitmap_full(cmd->region_map, cmd->nr_regions))
 737                 cmd->hydration_done = true;
 738
 739         return 0;
 740 }
 741
 742 static int __flush_dmap(struct dm_clone_metadata *cmd, struct dirty_map *dmap)
 743 {
 744         int r;
 745         unsigned long word;
 746
 747         word = 0;
 748         do {
 749                 word = find_next_bit(dmap->dirty_words, cmd->nr_words, word);
 750
 751                 if (word == cmd->nr_words)
 752                         break;
 753
 754                 r = __update_metadata_word(cmd, dmap->dirty_regions, word);
 755
 756                 if (r)
 757                         return r;
 758
 759                 __clear_bit(word, dmap->dirty_words);
 760                 word++;
 761         } while (word < cmd->nr_words);
 762
 763         r = __metadata_commit(cmd);
 764
 765         if (r)
 766                 return r;
 767
 768         /* Update the changed flag */
 769         spin_lock_irq(&cmd->bitmap_lock);
 770         dmap->changed = 0;
 771         spin_unlock_irq(&cmd->bitmap_lock);
 772
 773         return 0;
 774 }
 775
 776 int dm_clone_metadata_pre_commit(struct dm_clone_metadata *cmd)
 777 {
 778         int r = 0;
 779         struct dirty_map *dmap, *next_dmap;
 780
 781         down_write(&cmd->lock);
 782
 783         if (cmd->fail_io || dm_bm_is_read_only(cmd->bm)) {
 784                 r = -EPERM;
 785                 goto out;
 786         }
 787
 788         /* Get current dirty bitmap */
 789         dmap = cmd->current_dmap;
 790
 791         /* Get next dirty bitmap */
 792         next_dmap = (dmap == &cmd->dmap[0]) ? &cmd->dmap[1] : &cmd->dmap[0];
 793
 794         /*
 795          * The last commit failed, so we don't have a clean dirty-bitmap to
 796          * use.
 797          */
 798         if (WARN_ON(next_dmap->changed || cmd->committing_dmap)) {
 799                 r = -EINVAL;
 800                 goto out;
 801         }
 802
 803         /* Swap dirty bitmaps */
 804         spin_lock_irq(&cmd->bitmap_lock);
 805         cmd->current_dmap = next_dmap;
 806         spin_unlock_irq(&cmd->bitmap_lock);
 807
 808         /* Set old dirty bitmap as currently committing */
 809         cmd->committing_dmap = dmap;
 810 out:
 811         up_write(&cmd->lock);
 812
 813         return r;
 814 }
 815
 816 int dm_clone_metadata_commit(struct dm_clone_metadata *cmd)
 817 {
 818         int r = -EPERM;
 819
 820         down_write(&cmd->lock);
 821
 822         if (cmd->fail_io || dm_bm_is_read_only(cmd->bm))
 823                 goto out;
 824
 825         if (WARN_ON(!cmd->committing_dmap)) {
 826                 r = -EINVAL;
 827                 goto out;
 828         }
 829
 830         r = __flush_dmap(cmd, cmd->committing_dmap);
 831         if (!r) {
 832                 /* Clear committing dmap */
 833                 cmd->committing_dmap = NULL;
 834         }
 835 out:
 836         up_write(&cmd->lock);
 837
 838         return r;
 839 }
 840
 841 int dm_clone_set_region_hydrated(struct dm_clone_metadata *cmd, unsigned long region_nr)
 842 {
 843         int r = 0;
 844         struct dirty_map *dmap;
 845         unsigned long word, flags;
 846
 847         if (unlikely(region_nr >= cmd->nr_regions)) {
 848                 DMERR("Region %lu out of range (total number of regions %lu)",
 849                       region_nr, cmd->nr_regions);
 850                 return -ERANGE;
 851         }
 852
 853         word = region_nr / BITS_PER_LONG;
 854
 855         spin_lock_irqsave(&cmd->bitmap_lock, flags);
 856
 857         if (cmd->read_only) {
 858                 r = -EPERM;
 859                 goto out;
 860         }
 861
 862         dmap = cmd->current_dmap;
 863
 864         __set_bit(word, dmap->dirty_words);
 865         __set_bit(region_nr, dmap->dirty_regions);
 866         __set_bit(region_nr, cmd->region_map);
 867         dmap->changed = 1;
 868
 869 out:
 870         spin_unlock_irqrestore(&cmd->bitmap_lock, flags);
 871
 872         return r;
 873 }
 874
 875 int dm_clone_cond_set_range(struct dm_clone_metadata *cmd, unsigned long start,
 876                             unsigned long nr_regions)
 877 {
 878         int r = 0;
 879         struct dirty_map *dmap;
 880         unsigned long word, region_nr;
 881
 882         if (unlikely(start >= cmd->nr_regions || (start + nr_regions) < start ||
 883                      (start + nr_regions) > cmd->nr_regions)) {
 884                 DMERR("Invalid region range: start %lu, nr_regions %lu (total number of regions %lu)",
 885                       start, nr_regions, cmd->nr_regions);
 886                 return -ERANGE;
 887         }
 888
 889         spin_lock_irq(&cmd->bitmap_lock);
 890
 891         if (cmd->read_only) {
 892                 r = -EPERM;
 893                 goto out;
 894         }
 895
 896         dmap = cmd->current_dmap;
 897         for (region_nr = start; region_nr < (start + nr_regions); region_nr++) {
 898                 if (!test_bit(region_nr, cmd->region_map)) {
 899                         word = region_nr / BITS_PER_LONG;
 900                         __set_bit(word, dmap->dirty_words);
 901                         __set_bit(region_nr, dmap->dirty_regions);
 902                         __set_bit(region_nr, cmd->region_map);
 903                         dmap->changed = 1;
 904                 }
 905         }
 906 out:
 907         spin_unlock_irq(&cmd->bitmap_lock);
 908
 909         return r;
 910 }
 911
 912 /*
 913  * WARNING: This must not be called concurrently with either
 914  * dm_clone_set_region_hydrated() or dm_clone_cond_set_range(), as it changes
 915  * cmd->region_map without taking the cmd->bitmap_lock spinlock. The only
 916  * exception is after setting the metadata to read-only mode, using
 917  * dm_clone_metadata_set_read_only().
 918  *
 919  * We don't take the spinlock because __load_bitset_in_core() does I/O, so it
 920  * may block.
 921  */
 922 int dm_clone_reload_in_core_bitset(struct dm_clone_metadata *cmd)
 923 {
 924         int r = -EINVAL;
 925
 926         down_write(&cmd->lock);
 927
 928         if (cmd->fail_io)
 929                 goto out;
 930
 931         r = __load_bitset_in_core(cmd);
 932 out:
 933         up_write(&cmd->lock);
 934
 935         return r;
 936 }
 937
 938 bool dm_clone_changed_this_transaction(struct dm_clone_metadata *cmd)
 939 {
 940         bool r;
 941         unsigned long flags;
 942
 943         spin_lock_irqsave(&cmd->bitmap_lock, flags);
 944         r = cmd->dmap[0].changed || cmd->dmap[1].changed;
 945         spin_unlock_irqrestore(&cmd->bitmap_lock, flags);
 946
 947         return r;
 948 }
 949
 950 int dm_clone_metadata_abort(struct dm_clone_metadata *cmd)
 951 {
 952         int r = -EPERM;
 953
 954         down_write(&cmd->lock);
 955
 956         if (cmd->fail_io || dm_bm_is_read_only(cmd->bm))
 957                 goto out;
 958
 959         __destroy_persistent_data_structures(cmd);
 960
 961         r = __create_persistent_data_structures(cmd, false);
 962         if (r) {
 963                 /* If something went wrong we can neither write nor read the metadata */
 964                 cmd->fail_io = true;
 965         }
 966 out:
 967         up_write(&cmd->lock);
 968
 969         return r;
 970 }
 971
 972 void dm_clone_metadata_set_read_only(struct dm_clone_metadata *cmd)
 973 {
 974         down_write(&cmd->lock);
 975
 976         spin_lock_irq(&cmd->bitmap_lock);
 977         cmd->read_only = 1;
 978         spin_unlock_irq(&cmd->bitmap_lock);
 979
 980         if (!cmd->fail_io)
 981                 dm_bm_set_read_only(cmd->bm);
 982
 983         up_write(&cmd->lock);
 984 }
 985
 986 void dm_clone_metadata_set_read_write(struct dm_clone_metadata *cmd)
 987 {
 988         down_write(&cmd->lock);
 989
 990         spin_lock_irq(&cmd->bitmap_lock);
 991         cmd->read_only = 0;
 992         spin_unlock_irq(&cmd->bitmap_lock);
 993
 994         if (!cmd->fail_io)
 995                 dm_bm_set_read_write(cmd->bm);
 996
 997         up_write(&cmd->lock);
 998 }
 999
1000 int dm_clone_get_free_metadata_block_count(struct dm_clone_metadata *cmd,
1001                                            dm_block_t *result)
1002 {
1003         int r = -EINVAL;
1004
1005         down_read(&cmd->lock);
1006
1007         if (!cmd->fail_io)
1008                 r = dm_sm_get_nr_free(cmd->sm, result);
1009
1010         up_read(&cmd->lock);
1011
1012         return r;
1013 }
1014
1015 int dm_clone_get_metadata_dev_size(struct dm_clone_metadata *cmd,
1016                                    dm_block_t *result)
1017 {
1018         int r = -EINVAL;
1019
1020         down_read(&cmd->lock);
1021
1022         if (!cmd->fail_io)
1023                 r = dm_sm_get_nr_blocks(cmd->sm, result);
1024
1025         up_read(&cmd->lock);
1026
1027         return r;
1028 }