drivers/md/dm-era-target.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include "dm.h"
   3 #include "persistent-data/dm-transaction-manager.h"
   4 #include "persistent-data/dm-bitset.h"
   5 #include "persistent-data/dm-space-map.h"
   6
   7 #include <linux/dm-io.h>
   8 #include <linux/dm-kcopyd.h>
   9 #include <linux/init.h>
  10 #include <linux/mempool.h>
  11 #include <linux/module.h>
  12 #include <linux/slab.h>
  13 #include <linux/vmalloc.h>
  14
  15 #define DM_MSG_PREFIX "era"
  16
  17 #define SUPERBLOCK_LOCATION 0
  18 #define SUPERBLOCK_MAGIC 2126579579
  19 #define SUPERBLOCK_CSUM_XOR 146538381
  20 #define MIN_ERA_VERSION 1
  21 #define MAX_ERA_VERSION 1
  22 #define INVALID_WRITESET_ROOT SUPERBLOCK_LOCATION
  23 #define MIN_BLOCK_SIZE 8
  24
  25 /*----------------------------------------------------------------
  26  * Writeset
  27  *--------------------------------------------------------------*/
  28 struct writeset_metadata {
  29         uint32_t nr_bits;
  30         dm_block_t root;
  31 };
  32
  33 struct writeset {
  34         struct writeset_metadata md;
  35
  36         /*
  37          * An in core copy of the bits to save constantly doing look ups on
  38          * disk.
  39          */
  40         unsigned long *bits;
  41 };
  42
  43 /*
  44  * This does not free off the on disk bitset as this will normally be done
  45  * after digesting into the era array.
  46  */
  47 static void writeset_free(struct writeset *ws)
  48 {
  49         vfree(ws->bits);
  50 }
  51
  52 static int setup_on_disk_bitset(struct dm_disk_bitset *info,
  53                                 unsigned nr_bits, dm_block_t *root)
  54 {
  55         int r;
  56
  57         r = dm_bitset_empty(info, root);
  58         if (r)
  59                 return r;
  60
  61         return dm_bitset_resize(info, *root, 0, nr_bits, false, root);
  62 }
  63
  64 static size_t bitset_size(unsigned nr_bits)
  65 {
  66         return sizeof(unsigned long) * dm_div_up(nr_bits, BITS_PER_LONG);
  67 }
  68
  69 /*
  70  * Allocates memory for the in core bitset.
  71  */
  72 static int writeset_alloc(struct writeset *ws, dm_block_t nr_blocks)
  73 {
  74         ws->md.nr_bits = nr_blocks;
  75         ws->md.root = INVALID_WRITESET_ROOT;
  76         ws->bits = vzalloc(bitset_size(nr_blocks));
  77         if (!ws->bits) {
  78                 DMERR("%s: couldn't allocate in memory bitset", __func__);
  79                 return -ENOMEM;
  80         }
  81
  82         return 0;
  83 }
  84
  85 /*
  86  * Wipes the in-core bitset, and creates a new on disk bitset.
  87  */
  88 static int writeset_init(struct dm_disk_bitset *info, struct writeset *ws)
  89 {
  90         int r;
  91
  92         memset(ws->bits, 0, bitset_size(ws->md.nr_bits));
  93
  94         r = setup_on_disk_bitset(info, ws->md.nr_bits, &ws->md.root);
  95         if (r) {
  96                 DMERR("%s: setup_on_disk_bitset failed", __func__);
  97                 return r;
  98         }
  99
 100         return 0;
 101 }
 102
 103 static bool writeset_marked(struct writeset *ws, dm_block_t block)
 104 {
 105         return test_bit(block, ws->bits);
 106 }
 107
 108 static int writeset_marked_on_disk(struct dm_disk_bitset *info,
 109                                    struct writeset_metadata *m, dm_block_t block,
 110                                    bool *result)
 111 {
 112         dm_block_t old = m->root;
 113
 114         /*
 115          * The bitset was flushed when it was archived, so we know there'll
 116          * be no change to the root.
 117          */
 118         int r = dm_bitset_test_bit(info, m->root, block, &m->root, result);
 119         if (r) {
 120                 DMERR("%s: dm_bitset_test_bit failed", __func__);
 121                 return r;
 122         }
 123
 124         BUG_ON(m->root != old);
 125
 126         return r;
 127 }
 128
 129 /*
 130  * Returns < 0 on error, 0 if the bit wasn't previously set, 1 if it was.
 131  */
 132 static int writeset_test_and_set(struct dm_disk_bitset *info,
 133                                  struct writeset *ws, uint32_t block)
 134 {
 135         int r;
 136
 137         if (!test_and_set_bit(block, ws->bits)) {
 138                 r = dm_bitset_set_bit(info, ws->md.root, block, &ws->md.root);
 139                 if (r) {
 140                         /* FIXME: fail mode */
 141                         return r;
 142                 }
 143
 144                 return 0;
 145         }
 146
 147         return 1;
 148 }
 149
 150 /*----------------------------------------------------------------
 151  * On disk metadata layout
 152  *--------------------------------------------------------------*/
 153 #define SPACE_MAP_ROOT_SIZE 128
 154 #define UUID_LEN 16
 155
 156 struct writeset_disk {
 157         __le32 nr_bits;
 158         __le64 root;
 159 } __packed;
 160
 161 struct superblock_disk {
 162         __le32 csum;
 163         __le32 flags;
 164         __le64 blocknr;
 165
 166         __u8 uuid[UUID_LEN];
 167         __le64 magic;
 168         __le32 version;
 169
 170         __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
 171
 172         __le32 data_block_size;
 173         __le32 metadata_block_size;
 174         __le32 nr_blocks;
 175
 176         __le32 current_era;
 177         struct writeset_disk current_writeset;
 178
 179         /*
 180          * Only these two fields are valid within the metadata snapshot.
 181          */
 182         __le64 writeset_tree_root;
 183         __le64 era_array_root;
 184
 185         __le64 metadata_snap;
 186 } __packed;
 187
 188 /*----------------------------------------------------------------
 189  * Superblock validation
 190  *--------------------------------------------------------------*/
 191 static void sb_prepare_for_write(struct dm_block_validator *v,
 192                                  struct dm_block *b,
 193                                  size_t sb_block_size)
 194 {
 195         struct superblock_disk *disk = dm_block_data(b);
 196
 197         disk->blocknr = cpu_to_le64(dm_block_location(b));
 198         disk->csum = cpu_to_le32(dm_bm_checksum(&disk->flags,
 199                                                 sb_block_size - sizeof(__le32),
 200                                                 SUPERBLOCK_CSUM_XOR));
 201 }
 202
 203 static int check_metadata_version(struct superblock_disk *disk)
 204 {
 205         uint32_t metadata_version = le32_to_cpu(disk->version);
 206         if (metadata_version < MIN_ERA_VERSION || metadata_version > MAX_ERA_VERSION) {
 207                 DMERR("Era metadata version %u found, but only versions between %u and %u supported.",
 208                       metadata_version, MIN_ERA_VERSION, MAX_ERA_VERSION);
 209                 return -EINVAL;
 210         }
 211
 212         return 0;
 213 }
 214
 215 static int sb_check(struct dm_block_validator *v,
 216                     struct dm_block *b,
 217                     size_t sb_block_size)
 218 {
 219         struct superblock_disk *disk = dm_block_data(b);
 220         __le32 csum_le;
 221
 222         if (dm_block_location(b) != le64_to_cpu(disk->blocknr)) {
 223                 DMERR("sb_check failed: blocknr %llu: wanted %llu",
 224                       le64_to_cpu(disk->blocknr),
 225                       (unsigned long long)dm_block_location(b));
 226                 return -ENOTBLK;
 227         }
 228
 229         if (le64_to_cpu(disk->magic) != SUPERBLOCK_MAGIC) {
 230                 DMERR("sb_check failed: magic %llu: wanted %llu",
 231                       le64_to_cpu(disk->magic),
 232                       (unsigned long long) SUPERBLOCK_MAGIC);
 233                 return -EILSEQ;
 234         }
 235
 236         csum_le = cpu_to_le32(dm_bm_checksum(&disk->flags,
 237                                              sb_block_size - sizeof(__le32),
 238                                              SUPERBLOCK_CSUM_XOR));
 239         if (csum_le != disk->csum) {
 240                 DMERR("sb_check failed: csum %u: wanted %u",
 241                       le32_to_cpu(csum_le), le32_to_cpu(disk->csum));
 242                 return -EILSEQ;
 243         }
 244
 245         return check_metadata_version(disk);
 246 }
 247
 248 static struct dm_block_validator sb_validator = {
 249         .name = "superblock",
 250         .prepare_for_write = sb_prepare_for_write,
 251         .check = sb_check
 252 };
 253
 254 /*----------------------------------------------------------------
 255  * Low level metadata handling
 256  *--------------------------------------------------------------*/
 257 #define DM_ERA_METADATA_BLOCK_SIZE 4096
 258 #define ERA_MAX_CONCURRENT_LOCKS 5
 259
 260 struct era_metadata {
 261         struct block_device *bdev;
 262         struct dm_block_manager *bm;
 263         struct dm_space_map *sm;
 264         struct dm_transaction_manager *tm;
 265
 266         dm_block_t block_size;
 267         uint32_t nr_blocks;
 268
 269         uint32_t current_era;
 270
 271         /*
 272          * We preallocate 2 writesets.  When an era rolls over we
 273          * switch between them. This means the allocation is done at
 274          * preresume time, rather than on the io path.
 275          */
 276         struct writeset writesets[2];
 277         struct writeset *current_writeset;
 278
 279         dm_block_t writeset_tree_root;
 280         dm_block_t era_array_root;
 281
 282         struct dm_disk_bitset bitset_info;
 283         struct dm_btree_info writeset_tree_info;
 284         struct dm_array_info era_array_info;
 285
 286         dm_block_t metadata_snap;
 287
 288         /*
 289          * A flag that is set whenever a writeset has been archived.
 290          */
 291         bool archived_writesets;
 292
 293         /*
 294          * Reading the space map root can fail, so we read it into this
 295          * buffer before the superblock is locked and updated.
 296          */
 297         __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
 298 };
 299
 300 static int superblock_read_lock(struct era_metadata *md,
 301                                 struct dm_block **sblock)
 302 {
 303         return dm_bm_read_lock(md->bm, SUPERBLOCK_LOCATION,
 304                                &sb_validator, sblock);
 305 }
 306
 307 static int superblock_lock_zero(struct era_metadata *md,
 308                                 struct dm_block **sblock)
 309 {
 310         return dm_bm_write_lock_zero(md->bm, SUPERBLOCK_LOCATION,
 311                                      &sb_validator, sblock);
 312 }
 313
 314 static int superblock_lock(struct era_metadata *md,
 315                            struct dm_block **sblock)
 316 {
 317         return dm_bm_write_lock(md->bm, SUPERBLOCK_LOCATION,
 318                                 &sb_validator, sblock);
 319 }
 320
 321 /* FIXME: duplication with cache and thin */
 322 static int superblock_all_zeroes(struct dm_block_manager *bm, bool *result)
 323 {
 324         int r;
 325         unsigned i;
 326         struct dm_block *b;
 327         __le64 *data_le, zero = cpu_to_le64(0);
 328         unsigned sb_block_size = dm_bm_block_size(bm) / sizeof(__le64);
 329
 330         /*
 331          * We can't use a validator here - it may be all zeroes.
 332          */
 333         r = dm_bm_read_lock(bm, SUPERBLOCK_LOCATION, NULL, &b);
 334         if (r)
 335                 return r;
 336
 337         data_le = dm_block_data(b);
 338         *result = true;
 339         for (i = 0; i < sb_block_size; i++) {
 340                 if (data_le[i] != zero) {
 341                         *result = false;
 342                         break;
 343                 }
 344         }
 345
 346         dm_bm_unlock(b);
 347
 348         return 0;
 349 }
 350
 351 /*----------------------------------------------------------------*/
 352
 353 static void ws_pack(const struct writeset_metadata *core, struct writeset_disk *disk)
 354 {
 355         disk->nr_bits = cpu_to_le32(core->nr_bits);
 356         disk->root = cpu_to_le64(core->root);
 357 }
 358
 359 static void ws_unpack(const struct writeset_disk *disk, struct writeset_metadata *core)
 360 {
 361         core->nr_bits = le32_to_cpu(disk->nr_bits);
 362         core->root = le64_to_cpu(disk->root);
 363 }
 364
 365 static void ws_inc(void *context, const void *value)
 366 {
 367         struct era_metadata *md = context;
 368         struct writeset_disk ws_d;
 369         dm_block_t b;
 370
 371         memcpy(&ws_d, value, sizeof(ws_d));
 372         b = le64_to_cpu(ws_d.root);
 373
 374         dm_tm_inc(md->tm, b);
 375 }
 376
 377 static void ws_dec(void *context, const void *value)
 378 {
 379         struct era_metadata *md = context;
 380         struct writeset_disk ws_d;
 381         dm_block_t b;
 382
 383         memcpy(&ws_d, value, sizeof(ws_d));
 384         b = le64_to_cpu(ws_d.root);
 385
 386         dm_bitset_del(&md->bitset_info, b);
 387 }
 388
 389 static int ws_eq(void *context, const void *value1, const void *value2)
 390 {
 391         return !memcmp(value1, value2, sizeof(struct writeset_metadata));
 392 }
 393
 394 /*----------------------------------------------------------------*/
 395
 396 static void setup_writeset_tree_info(struct era_metadata *md)
 397 {
 398         struct dm_btree_value_type *vt = &md->writeset_tree_info.value_type;
 399         md->writeset_tree_info.tm = md->tm;
 400         md->writeset_tree_info.levels = 1;
 401         vt->context = md;
 402         vt->size = sizeof(struct writeset_disk);
 403         vt->inc = ws_inc;
 404         vt->dec = ws_dec;
 405         vt->equal = ws_eq;
 406 }
 407
 408 static void setup_era_array_info(struct era_metadata *md)
 409
 410 {
 411         struct dm_btree_value_type vt;
 412         vt.context = NULL;
 413         vt.size = sizeof(__le32);
 414         vt.inc = NULL;
 415         vt.dec = NULL;
 416         vt.equal = NULL;
 417
 418         dm_array_info_init(&md->era_array_info, md->tm, &vt);
 419 }
 420
 421 static void setup_infos(struct era_metadata *md)
 422 {
 423         dm_disk_bitset_init(md->tm, &md->bitset_info);
 424         setup_writeset_tree_info(md);
 425         setup_era_array_info(md);
 426 }
 427
 428 /*----------------------------------------------------------------*/
 429
 430 static int create_fresh_metadata(struct era_metadata *md)
 431 {
 432         int r;
 433
 434         r = dm_tm_create_with_sm(md->bm, SUPERBLOCK_LOCATION,
 435                                  &md->tm, &md->sm);
 436         if (r < 0) {
 437                 DMERR("dm_tm_create_with_sm failed");
 438                 return r;
 439         }
 440
 441         setup_infos(md);
 442
 443         r = dm_btree_empty(&md->writeset_tree_info, &md->writeset_tree_root);
 444         if (r) {
 445                 DMERR("couldn't create new writeset tree");
 446                 goto bad;
 447         }
 448
 449         r = dm_array_empty(&md->era_array_info, &md->era_array_root);
 450         if (r) {
 451                 DMERR("couldn't create era array");
 452                 goto bad;
 453         }
 454
 455         return 0;
 456
 457 bad:
 458         dm_sm_destroy(md->sm);
 459         dm_tm_destroy(md->tm);
 460
 461         return r;
 462 }
 463
 464 static int save_sm_root(struct era_metadata *md)
 465 {
 466         int r;
 467         size_t metadata_len;
 468
 469         r = dm_sm_root_size(md->sm, &metadata_len);
 470         if (r < 0)
 471                 return r;
 472
 473         return dm_sm_copy_root(md->sm, &md->metadata_space_map_root,
 474                                metadata_len);
 475 }
 476
 477 static void copy_sm_root(struct era_metadata *md, struct superblock_disk *disk)
 478 {
 479         memcpy(&disk->metadata_space_map_root,
 480                &md->metadata_space_map_root,
 481                sizeof(md->metadata_space_map_root));
 482 }
 483
 484 /*
 485  * Writes a superblock, including the static fields that don't get updated
 486  * with every commit (possible optimisation here).  'md' should be fully
 487  * constructed when this is called.
 488  */
 489 static void prepare_superblock(struct era_metadata *md, struct superblock_disk *disk)
 490 {
 491         disk->magic = cpu_to_le64(SUPERBLOCK_MAGIC);
 492         disk->flags = cpu_to_le32(0ul);
 493
 494         /* FIXME: can't keep blanking the uuid (uuid is currently unused though) */
 495         memset(disk->uuid, 0, sizeof(disk->uuid));
 496         disk->version = cpu_to_le32(MAX_ERA_VERSION);
 497
 498         copy_sm_root(md, disk);
 499
 500         disk->data_block_size = cpu_to_le32(md->block_size);
 501         disk->metadata_block_size = cpu_to_le32(DM_ERA_METADATA_BLOCK_SIZE >> SECTOR_SHIFT);
 502         disk->nr_blocks = cpu_to_le32(md->nr_blocks);
 503         disk->current_era = cpu_to_le32(md->current_era);
 504
 505         ws_pack(&md->current_writeset->md, &disk->current_writeset);
 506         disk->writeset_tree_root = cpu_to_le64(md->writeset_tree_root);
 507         disk->era_array_root = cpu_to_le64(md->era_array_root);
 508         disk->metadata_snap = cpu_to_le64(md->metadata_snap);
 509 }
 510
 511 static int write_superblock(struct era_metadata *md)
 512 {
 513         int r;
 514         struct dm_block *sblock;
 515         struct superblock_disk *disk;
 516
 517         r = save_sm_root(md);
 518         if (r) {
 519                 DMERR("%s: save_sm_root failed", __func__);
 520                 return r;
 521         }
 522
 523         r = superblock_lock_zero(md, &sblock);
 524         if (r)
 525                 return r;
 526
 527         disk = dm_block_data(sblock);
 528         prepare_superblock(md, disk);
 529
 530         return dm_tm_commit(md->tm, sblock);
 531 }
 532
 533 /*
 534  * Assumes block_size and the infos are set.
 535  */
 536 static int format_metadata(struct era_metadata *md)
 537 {
 538         int r;
 539
 540         r = create_fresh_metadata(md);
 541         if (r)
 542                 return r;
 543
 544         r = write_superblock(md);
 545         if (r) {
 546                 dm_sm_destroy(md->sm);
 547                 dm_tm_destroy(md->tm);
 548                 return r;
 549         }
 550
 551         return 0;
 552 }
 553
 554 static int open_metadata(struct era_metadata *md)
 555 {
 556         int r;
 557         struct dm_block *sblock;
 558         struct superblock_disk *disk;
 559
 560         r = superblock_read_lock(md, &sblock);
 561         if (r) {
 562                 DMERR("couldn't read_lock superblock");
 563                 return r;
 564         }
 565
 566         disk = dm_block_data(sblock);
 567         r = dm_tm_open_with_sm(md->bm, SUPERBLOCK_LOCATION,
 568                                disk->metadata_space_map_root,
 569                                sizeof(disk->metadata_space_map_root),
 570                                &md->tm, &md->sm);
 571         if (r) {
 572                 DMERR("dm_tm_open_with_sm failed");
 573                 goto bad;
 574         }
 575
 576         setup_infos(md);
 577
 578         md->block_size = le32_to_cpu(disk->data_block_size);
 579         md->nr_blocks = le32_to_cpu(disk->nr_blocks);
 580         md->current_era = le32_to_cpu(disk->current_era);
 581
 582         md->writeset_tree_root = le64_to_cpu(disk->writeset_tree_root);
 583         md->era_array_root = le64_to_cpu(disk->era_array_root);
 584         md->metadata_snap = le64_to_cpu(disk->metadata_snap);
 585         md->archived_writesets = true;
 586
 587         dm_bm_unlock(sblock);
 588
 589         return 0;
 590
 591 bad:
 592         dm_bm_unlock(sblock);
 593         return r;
 594 }
 595
 596 static int open_or_format_metadata(struct era_metadata *md,
 597                                    bool may_format)
 598 {
 599         int r;
 600         bool unformatted = false;
 601
 602         r = superblock_all_zeroes(md->bm, &unformatted);
 603         if (r)
 604                 return r;
 605
 606         if (unformatted)
 607                 return may_format ? format_metadata(md) : -EPERM;
 608
 609         return open_metadata(md);
 610 }
 611
 612 static int create_persistent_data_objects(struct era_metadata *md,
 613                                           bool may_format)
 614 {
 615         int r;
 616
 617         md->bm = dm_block_manager_create(md->bdev, DM_ERA_METADATA_BLOCK_SIZE,
 618                                          ERA_MAX_CONCURRENT_LOCKS);
 619         if (IS_ERR(md->bm)) {
 620                 DMERR("could not create block manager");
 621                 return PTR_ERR(md->bm);
 622         }
 623
 624         r = open_or_format_metadata(md, may_format);
 625         if (r)
 626                 dm_block_manager_destroy(md->bm);
 627
 628         return r;
 629 }
 630
 631 static void destroy_persistent_data_objects(struct era_metadata *md)
 632 {
 633         dm_sm_destroy(md->sm);
 634         dm_tm_destroy(md->tm);
 635         dm_block_manager_destroy(md->bm);
 636 }
 637
 638 /*
 639  * This waits until all era_map threads have picked up the new filter.
 640  */
 641 static void swap_writeset(struct era_metadata *md, struct writeset *new_writeset)
 642 {
 643         rcu_assign_pointer(md->current_writeset, new_writeset);
 644         synchronize_rcu();
 645 }
 646
 647 /*----------------------------------------------------------------
 648  * Writesets get 'digested' into the main era array.
 649  *
 650  * We're using a coroutine here so the worker thread can do the digestion,
 651  * thus avoiding synchronisation of the metadata.  Digesting a whole
 652  * writeset in one go would cause too much latency.
 653  *--------------------------------------------------------------*/
 654 struct digest {
 655         uint32_t era;
 656         unsigned nr_bits, current_bit;
 657         struct writeset_metadata writeset;
 658         __le32 value;
 659         struct dm_disk_bitset info;
 660
 661         int (*step)(struct era_metadata *, struct digest *);
 662 };
 663
 664 static int metadata_digest_lookup_writeset(struct era_metadata *md,
 665                                            struct digest *d);
 666
 667 static int metadata_digest_remove_writeset(struct era_metadata *md,
 668                                            struct digest *d)
 669 {
 670         int r;
 671         uint64_t key = d->era;
 672
 673         r = dm_btree_remove(&md->writeset_tree_info, md->writeset_tree_root,
 674                             &key, &md->writeset_tree_root);
 675         if (r) {
 676                 DMERR("%s: dm_btree_remove failed", __func__);
 677                 return r;
 678         }
 679
 680         d->step = metadata_digest_lookup_writeset;
 681         return 0;
 682 }
 683
 684 #define INSERTS_PER_STEP 100
 685
 686 static int metadata_digest_transcribe_writeset(struct era_metadata *md,
 687                                                struct digest *d)
 688 {
 689         int r;
 690         bool marked;
 691         unsigned b, e = min(d->current_bit + INSERTS_PER_STEP, d->nr_bits);
 692
 693         for (b = d->current_bit; b < e; b++) {
 694                 r = writeset_marked_on_disk(&d->info, &d->writeset, b, &marked);
 695                 if (r) {
 696                         DMERR("%s: writeset_marked_on_disk failed", __func__);
 697                         return r;
 698                 }
 699
 700                 if (!marked)
 701                         continue;
 702
 703                 __dm_bless_for_disk(&d->value);
 704                 r = dm_array_set_value(&md->era_array_info, md->era_array_root,
 705                                        b, &d->value, &md->era_array_root);
 706                 if (r) {
 707                         DMERR("%s: dm_array_set_value failed", __func__);
 708                         return r;
 709                 }
 710         }
 711
 712         if (b == d->nr_bits)
 713                 d->step = metadata_digest_remove_writeset;
 714         else
 715                 d->current_bit = b;
 716
 717         return 0;
 718 }
 719
 720 static int metadata_digest_lookup_writeset(struct era_metadata *md,
 721                                            struct digest *d)
 722 {
 723         int r;
 724         uint64_t key;
 725         struct writeset_disk disk;
 726
 727         r = dm_btree_find_lowest_key(&md->writeset_tree_info,
 728                                      md->writeset_tree_root, &key);
 729         if (r < 0)
 730                 return r;
 731
 732         d->era = key;
 733
 734         r = dm_btree_lookup(&md->writeset_tree_info,
 735                             md->writeset_tree_root, &key, &disk);
 736         if (r) {
 737                 if (r == -ENODATA) {
 738                         d->step = NULL;
 739                         return 0;
 740                 }
 741
 742                 DMERR("%s: dm_btree_lookup failed", __func__);
 743                 return r;
 744         }
 745
 746         ws_unpack(&disk, &d->writeset);
 747         d->value = cpu_to_le32(key);
 748
 749         d->nr_bits = min(d->writeset.nr_bits, md->nr_blocks);
 750         d->current_bit = 0;
 751         d->step = metadata_digest_transcribe_writeset;
 752
 753         return 0;
 754 }
 755
 756 static int metadata_digest_start(struct era_metadata *md, struct digest *d)
 757 {
 758         if (d->step)
 759                 return 0;
 760
 761         memset(d, 0, sizeof(*d));
 762
 763         /*
 764          * We initialise another bitset info to avoid any caching side
 765          * effects with the previous one.
 766          */
 767         dm_disk_bitset_init(md->tm, &d->info);
 768         d->step = metadata_digest_lookup_writeset;
 769
 770         return 0;
 771 }
 772
 773 /*----------------------------------------------------------------
 774  * High level metadata interface.  Target methods should use these, and not
 775  * the lower level ones.
 776  *--------------------------------------------------------------*/
 777 static struct era_metadata *metadata_open(struct block_device *bdev,
 778                                           sector_t block_size,
 779                                           bool may_format)
 780 {
 781         int r;
 782         struct era_metadata *md = kzalloc(sizeof(*md), GFP_KERNEL);
 783
 784         if (!md)
 785                 return NULL;
 786
 787         md->bdev = bdev;
 788         md->block_size = block_size;
 789
 790         md->writesets[0].md.root = INVALID_WRITESET_ROOT;
 791         md->writesets[1].md.root = INVALID_WRITESET_ROOT;
 792         md->current_writeset = &md->writesets[0];
 793
 794         r = create_persistent_data_objects(md, may_format);
 795         if (r) {
 796                 kfree(md);
 797                 return ERR_PTR(r);
 798         }
 799
 800         return md;
 801 }
 802
 803 static void metadata_close(struct era_metadata *md)
 804 {
 805         destroy_persistent_data_objects(md);
 806         kfree(md);
 807 }
 808
 809 static bool valid_nr_blocks(dm_block_t n)
 810 {
 811         /*
 812          * dm_bitset restricts us to 2^32.  test_bit & co. restrict us
 813          * further to 2^31 - 1
 814          */
 815         return n < (1ull << 31);
 816 }
 817
 818 static int metadata_resize(struct era_metadata *md, void *arg)
 819 {
 820         int r;
 821         dm_block_t *new_size = arg;
 822         __le32 value;
 823
 824         if (!valid_nr_blocks(*new_size)) {
 825                 DMERR("Invalid number of origin blocks %llu",
 826                       (unsigned long long) *new_size);
 827                 return -EINVAL;
 828         }
 829
 830         writeset_free(&md->writesets[0]);
 831         writeset_free(&md->writesets[1]);
 832
 833         r = writeset_alloc(&md->writesets[0], *new_size);
 834         if (r) {
 835                 DMERR("%s: writeset_alloc failed for writeset 0", __func__);
 836                 return r;
 837         }
 838
 839         r = writeset_alloc(&md->writesets[1], *new_size);
 840         if (r) {
 841                 DMERR("%s: writeset_alloc failed for writeset 1", __func__);
 842                 return r;
 843         }
 844
 845         value = cpu_to_le32(0u);
 846         __dm_bless_for_disk(&value);
 847         r = dm_array_resize(&md->era_array_info, md->era_array_root,
 848                             md->nr_blocks, *new_size,
 849                             &value, &md->era_array_root);
 850         if (r) {
 851                 DMERR("%s: dm_array_resize failed", __func__);
 852                 return r;
 853         }
 854
 855         md->nr_blocks = *new_size;
 856         return 0;
 857 }
 858
 859 static int metadata_era_archive(struct era_metadata *md)
 860 {
 861         int r;
 862         uint64_t keys[1];
 863         struct writeset_disk value;
 864
 865         r = dm_bitset_flush(&md->bitset_info, md->current_writeset->md.root,
 866                             &md->current_writeset->md.root);
 867         if (r) {
 868                 DMERR("%s: dm_bitset_flush failed", __func__);
 869                 return r;
 870         }
 871
 872         ws_pack(&md->current_writeset->md, &value);
 873         md->current_writeset->md.root = INVALID_WRITESET_ROOT;
 874
 875         keys[0] = md->current_era;
 876         __dm_bless_for_disk(&value);
 877         r = dm_btree_insert(&md->writeset_tree_info, md->writeset_tree_root,
 878                             keys, &value, &md->writeset_tree_root);
 879         if (r) {
 880                 DMERR("%s: couldn't insert writeset into btree", __func__);
 881                 /* FIXME: fail mode */
 882                 return r;
 883         }
 884
 885         md->archived_writesets = true;
 886
 887         return 0;
 888 }
 889
 890 static struct writeset *next_writeset(struct era_metadata *md)
 891 {
 892         return (md->current_writeset == &md->writesets[0]) ?
 893                 &md->writesets[1] : &md->writesets[0];
 894 }
 895
 896 static int metadata_new_era(struct era_metadata *md)
 897 {
 898         int r;
 899         struct writeset *new_writeset = next_writeset(md);
 900
 901         r = writeset_init(&md->bitset_info, new_writeset);
 902         if (r) {
 903                 DMERR("%s: writeset_init failed", __func__);
 904                 return r;
 905         }
 906
 907         swap_writeset(md, new_writeset);
 908         md->current_era++;
 909
 910         return 0;
 911 }
 912
 913 static int metadata_era_rollover(struct era_metadata *md)
 914 {
 915         int r;
 916
 917         if (md->current_writeset->md.root != INVALID_WRITESET_ROOT) {
 918                 r = metadata_era_archive(md);
 919                 if (r) {
 920                         DMERR("%s: metadata_archive_era failed", __func__);
 921                         /* FIXME: fail mode? */
 922                         return r;
 923                 }
 924         }
 925
 926         r = metadata_new_era(md);
 927         if (r) {
 928                 DMERR("%s: new era failed", __func__);
 929                 /* FIXME: fail mode */
 930                 return r;
 931         }
 932
 933         return 0;
 934 }
 935
 936 static bool metadata_current_marked(struct era_metadata *md, dm_block_t block)
 937 {
 938         bool r;
 939         struct writeset *ws;
 940
 941         rcu_read_lock();
 942         ws = rcu_dereference(md->current_writeset);
 943         r = writeset_marked(ws, block);
 944         rcu_read_unlock();
 945
 946         return r;
 947 }
 948
 949 static int metadata_commit(struct era_metadata *md)
 950 {
 951         int r;
 952         struct dm_block *sblock;
 953
 954         if (md->current_writeset->md.root != SUPERBLOCK_LOCATION) {
 955                 r = dm_bitset_flush(&md->bitset_info, md->current_writeset->md.root,
 956                                     &md->current_writeset->md.root);
 957                 if (r) {
 958                         DMERR("%s: bitset flush failed", __func__);
 959                         return r;
 960                 }
 961         }
 962
 963         r = dm_tm_pre_commit(md->tm);
 964         if (r) {
 965                 DMERR("%s: pre commit failed", __func__);
 966                 return r;
 967         }
 968
 969         r = save_sm_root(md);
 970         if (r) {
 971                 DMERR("%s: save_sm_root failed", __func__);
 972                 return r;
 973         }
 974
 975         r = superblock_lock(md, &sblock);
 976         if (r) {
 977                 DMERR("%s: superblock lock failed", __func__);
 978                 return r;
 979         }
 980
 981         prepare_superblock(md, dm_block_data(sblock));
 982
 983         return dm_tm_commit(md->tm, sblock);
 984 }
 985
 986 static int metadata_checkpoint(struct era_metadata *md)
 987 {
 988         /*
 989          * For now we just rollover, but later I want to put a check in to
 990          * avoid this if the filter is still pretty fresh.
 991          */
 992         return metadata_era_rollover(md);
 993 }
 994
 995 /*
 996  * Metadata snapshots allow userland to access era data.
 997  */
 998 static int metadata_take_snap(struct era_metadata *md)
 999 {
1000         int r, inc;
1001         struct dm_block *clone;
1002
1003         if (md->metadata_snap != SUPERBLOCK_LOCATION) {
1004                 DMERR("%s: metadata snapshot already exists", __func__);
1005                 return -EINVAL;
1006         }
1007
1008         r = metadata_era_rollover(md);
1009         if (r) {
1010                 DMERR("%s: era rollover failed", __func__);
1011                 return r;
1012         }
1013
1014         r = metadata_commit(md);
1015         if (r) {
1016                 DMERR("%s: pre commit failed", __func__);
1017                 return r;
1018         }
1019
1020         r = dm_sm_inc_block(md->sm, SUPERBLOCK_LOCATION);
1021         if (r) {
1022                 DMERR("%s: couldn't increment superblock", __func__);
1023                 return r;
1024         }
1025
1026         r = dm_tm_shadow_block(md->tm, SUPERBLOCK_LOCATION,
1027                                &sb_validator, &clone, &inc);
1028         if (r) {
1029                 DMERR("%s: couldn't shadow superblock", __func__);
1030                 dm_sm_dec_block(md->sm, SUPERBLOCK_LOCATION);
1031                 return r;
1032         }
1033         BUG_ON(!inc);
1034
1035         r = dm_sm_inc_block(md->sm, md->writeset_tree_root);
1036         if (r) {
1037                 DMERR("%s: couldn't inc writeset tree root", __func__);
1038                 dm_tm_unlock(md->tm, clone);
1039                 return r;
1040         }
1041
1042         r = dm_sm_inc_block(md->sm, md->era_array_root);
1043         if (r) {
1044                 DMERR("%s: couldn't inc era tree root", __func__);
1045                 dm_sm_dec_block(md->sm, md->writeset_tree_root);
1046                 dm_tm_unlock(md->tm, clone);
1047                 return r;
1048         }
1049
1050         md->metadata_snap = dm_block_location(clone);
1051
1052         dm_tm_unlock(md->tm, clone);
1053
1054         return 0;
1055 }
1056
1057 static int metadata_drop_snap(struct era_metadata *md)
1058 {
1059         int r;
1060         dm_block_t location;
1061         struct dm_block *clone;
1062         struct superblock_disk *disk;
1063
1064         if (md->metadata_snap == SUPERBLOCK_LOCATION) {
1065                 DMERR("%s: no snap to drop", __func__);
1066                 return -EINVAL;
1067         }
1068
1069         r = dm_tm_read_lock(md->tm, md->metadata_snap, &sb_validator, &clone);
1070         if (r) {
1071                 DMERR("%s: couldn't read lock superblock clone", __func__);
1072                 return r;
1073         }
1074
1075         /*
1076          * Whatever happens now we'll commit with no record of the metadata
1077          * snap.
1078          */
1079         md->metadata_snap = SUPERBLOCK_LOCATION;
1080
1081         disk = dm_block_data(clone);
1082         r = dm_btree_del(&md->writeset_tree_info,
1083                          le64_to_cpu(disk->writeset_tree_root));
1084         if (r) {
1085                 DMERR("%s: error deleting writeset tree clone", __func__);
1086                 dm_tm_unlock(md->tm, clone);
1087                 return r;
1088         }
1089
1090         r = dm_array_del(&md->era_array_info, le64_to_cpu(disk->era_array_root));
1091         if (r) {
1092                 DMERR("%s: error deleting era array clone", __func__);
1093                 dm_tm_unlock(md->tm, clone);
1094                 return r;
1095         }
1096
1097         location = dm_block_location(clone);
1098         dm_tm_unlock(md->tm, clone);
1099
1100         return dm_sm_dec_block(md->sm, location);
1101 }
1102
1103 struct metadata_stats {
1104         dm_block_t used;
1105         dm_block_t total;
1106         dm_block_t snap;
1107         uint32_t era;
1108 };
1109
1110 static int metadata_get_stats(struct era_metadata *md, void *ptr)
1111 {
1112         int r;
1113         struct metadata_stats *s = ptr;
1114         dm_block_t nr_free, nr_total;
1115
1116         r = dm_sm_get_nr_free(md->sm, &nr_free);
1117         if (r) {
1118                 DMERR("dm_sm_get_nr_free returned %d", r);
1119                 return r;
1120         }
1121
1122         r = dm_sm_get_nr_blocks(md->sm, &nr_total);
1123         if (r) {
1124                 DMERR("dm_pool_get_metadata_dev_size returned %d", r);
1125                 return r;
1126         }
1127
1128         s->used = nr_total - nr_free;
1129         s->total = nr_total;
1130         s->snap = md->metadata_snap;
1131         s->era = md->current_era;
1132
1133         return 0;
1134 }
1135
1136 /*----------------------------------------------------------------*/
1137
1138 struct era {
1139         struct dm_target *ti;
1140
1141         struct dm_dev *metadata_dev;
1142         struct dm_dev *origin_dev;
1143
1144         dm_block_t nr_blocks;
1145         uint32_t sectors_per_block;
1146         int sectors_per_block_shift;
1147         struct era_metadata *md;
1148
1149         struct workqueue_struct *wq;
1150         struct work_struct worker;
1151
1152         spinlock_t deferred_lock;
1153         struct bio_list deferred_bios;
1154
1155         spinlock_t rpc_lock;
1156         struct list_head rpc_calls;
1157
1158         struct digest digest;
1159         atomic_t suspended;
1160 };
1161
1162 struct rpc {
1163         struct list_head list;
1164
1165         int (*fn0)(struct era_metadata *);
1166         int (*fn1)(struct era_metadata *, void *);
1167         void *arg;
1168         int result;
1169
1170         struct completion complete;
1171 };
1172
1173 /*----------------------------------------------------------------
1174  * Remapping.
1175  *---------------------------------------------------------------*/
1176 static bool block_size_is_power_of_two(struct era *era)
1177 {
1178         return era->sectors_per_block_shift >= 0;
1179 }
1180
1181 static dm_block_t get_block(struct era *era, struct bio *bio)
1182 {
1183         sector_t block_nr = bio->bi_iter.bi_sector;
1184
1185         if (!block_size_is_power_of_two(era))
1186                 (void) sector_div(block_nr, era->sectors_per_block);
1187         else
1188                 block_nr >>= era->sectors_per_block_shift;
1189
1190         return block_nr;
1191 }
1192
1193 static void remap_to_origin(struct era *era, struct bio *bio)
1194 {
1195         bio_set_dev(bio, era->origin_dev->bdev);
1196 }
1197
1198 /*----------------------------------------------------------------
1199  * Worker thread
1200  *--------------------------------------------------------------*/
1201 static void wake_worker(struct era *era)
1202 {
1203         if (!atomic_read(&era->suspended))
1204                 queue_work(era->wq, &era->worker);
1205 }
1206
1207 static void process_old_eras(struct era *era)
1208 {
1209         int r;
1210
1211         if (!era->digest.step)
1212                 return;
1213
1214         r = era->digest.step(era->md, &era->digest);
1215         if (r < 0) {
1216                 DMERR("%s: digest step failed, stopping digestion", __func__);
1217                 era->digest.step = NULL;
1218
1219         } else if (era->digest.step)
1220                 wake_worker(era);
1221 }
1222
1223 static void process_deferred_bios(struct era *era)
1224 {
1225         int r;
1226         struct bio_list deferred_bios, marked_bios;
1227         struct bio *bio;
1228         bool commit_needed = false;
1229         bool failed = false;
1230
1231         bio_list_init(&deferred_bios);
1232         bio_list_init(&marked_bios);
1233
1234         spin_lock(&era->deferred_lock);
1235         bio_list_merge(&deferred_bios, &era->deferred_bios);
1236         bio_list_init(&era->deferred_bios);
1237         spin_unlock(&era->deferred_lock);
1238
1239         while ((bio = bio_list_pop(&deferred_bios))) {
1240                 r = writeset_test_and_set(&era->md->bitset_info,
1241                                           era->md->current_writeset,
1242                                           get_block(era, bio));
1243                 if (r < 0) {
1244                         /*
1245                          * This is bad news, we need to rollback.
1246                          * FIXME: finish.
1247                          */
1248                         failed = true;
1249
1250                 } else if (r == 0)
1251                         commit_needed = true;
1252
1253                 bio_list_add(&marked_bios, bio);
1254         }
1255
1256         if (commit_needed) {
1257                 r = metadata_commit(era->md);
1258                 if (r)
1259                         failed = true;
1260         }
1261
1262         if (failed)
1263                 while ((bio = bio_list_pop(&marked_bios)))
1264                         bio_io_error(bio);
1265         else
1266                 while ((bio = bio_list_pop(&marked_bios)))
1267                         submit_bio_noacct(bio);
1268 }
1269
1270 static void process_rpc_calls(struct era *era)
1271 {
1272         int r;
1273         bool need_commit = false;
1274         struct list_head calls;
1275         struct rpc *rpc, *tmp;
1276
1277         INIT_LIST_HEAD(&calls);
1278         spin_lock(&era->rpc_lock);
1279         list_splice_init(&era->rpc_calls, &calls);
1280         spin_unlock(&era->rpc_lock);
1281
1282         list_for_each_entry_safe(rpc, tmp, &calls, list) {
1283                 rpc->result = rpc->fn0 ? rpc->fn0(era->md) : rpc->fn1(era->md, rpc->arg);
1284                 need_commit = true;
1285         }
1286
1287         if (need_commit) {
1288                 r = metadata_commit(era->md);
1289                 if (r)
1290                         list_for_each_entry_safe(rpc, tmp, &calls, list)
1291                                 rpc->result = r;
1292         }
1293
1294         list_for_each_entry_safe(rpc, tmp, &calls, list)
1295                 complete(&rpc->complete);
1296 }
1297
1298 static void kick_off_digest(struct era *era)
1299 {
1300         if (era->md->archived_writesets) {
1301                 era->md->archived_writesets = false;
1302                 metadata_digest_start(era->md, &era->digest);
1303         }
1304 }
1305
1306 static void do_work(struct work_struct *ws)
1307 {
1308         struct era *era = container_of(ws, struct era, worker);
1309
1310         kick_off_digest(era);
1311         process_old_eras(era);
1312         process_deferred_bios(era);
1313         process_rpc_calls(era);
1314 }
1315
1316 static void defer_bio(struct era *era, struct bio *bio)
1317 {
1318         spin_lock(&era->deferred_lock);
1319         bio_list_add(&era->deferred_bios, bio);
1320         spin_unlock(&era->deferred_lock);
1321
1322         wake_worker(era);
1323 }
1324
1325 /*
1326  * Make an rpc call to the worker to change the metadata.
1327  */
1328 static int perform_rpc(struct era *era, struct rpc *rpc)
1329 {
1330         rpc->result = 0;
1331         init_completion(&rpc->complete);
1332
1333         spin_lock(&era->rpc_lock);
1334         list_add(&rpc->list, &era->rpc_calls);
1335         spin_unlock(&era->rpc_lock);
1336
1337         wake_worker(era);
1338         wait_for_completion(&rpc->complete);
1339
1340         return rpc->result;
1341 }
1342
1343 static int in_worker0(struct era *era, int (*fn)(struct era_metadata *))
1344 {
1345         struct rpc rpc;
1346         rpc.fn0 = fn;
1347         rpc.fn1 = NULL;
1348
1349         return perform_rpc(era, &rpc);
1350 }
1351
1352 static int in_worker1(struct era *era,
1353                       int (*fn)(struct era_metadata *, void *), void *arg)
1354 {
1355         struct rpc rpc;
1356         rpc.fn0 = NULL;
1357         rpc.fn1 = fn;
1358         rpc.arg = arg;
1359
1360         return perform_rpc(era, &rpc);
1361 }
1362
1363 static void start_worker(struct era *era)
1364 {
1365         atomic_set(&era->suspended, 0);
1366 }
1367
1368 static void stop_worker(struct era *era)
1369 {
1370         atomic_set(&era->suspended, 1);
1371         flush_workqueue(era->wq);
1372 }
1373
1374 /*----------------------------------------------------------------
1375  * Target methods
1376  *--------------------------------------------------------------*/
1377 static void era_destroy(struct era *era)
1378 {
1379         if (era->md)
1380                 metadata_close(era->md);
1381
1382         if (era->wq)
1383                 destroy_workqueue(era->wq);
1384
1385         if (era->origin_dev)
1386                 dm_put_device(era->ti, era->origin_dev);
1387
1388         if (era->metadata_dev)
1389                 dm_put_device(era->ti, era->metadata_dev);
1390
1391         kfree(era);
1392 }
1393
1394 static dm_block_t calc_nr_blocks(struct era *era)
1395 {
1396         return dm_sector_div_up(era->ti->len, era->sectors_per_block);
1397 }
1398
1399 static bool valid_block_size(dm_block_t block_size)
1400 {
1401         bool greater_than_zero = block_size > 0;
1402         bool multiple_of_min_block_size = (block_size & (MIN_BLOCK_SIZE - 1)) == 0;
1403
1404         return greater_than_zero && multiple_of_min_block_size;
1405 }
1406
1407 /*
1408  * <metadata dev> <data dev> <data block size (sectors)>
1409  */
1410 static int era_ctr(struct dm_target *ti, unsigned argc, char **argv)
1411 {
1412         int r;
1413         char dummy;
1414         struct era *era;
1415         struct era_metadata *md;
1416
1417         if (argc != 3) {
1418                 ti->error = "Invalid argument count";
1419                 return -EINVAL;
1420         }
1421
1422         era = kzalloc(sizeof(*era), GFP_KERNEL);
1423         if (!era) {
1424                 ti->error = "Error allocating era structure";
1425                 return -ENOMEM;
1426         }
1427
1428         era->ti = ti;
1429
1430         r = dm_get_device(ti, argv[0], FMODE_READ | FMODE_WRITE, &era->metadata_dev);
1431         if (r) {
1432                 ti->error = "Error opening metadata device";
1433                 era_destroy(era);
1434                 return -EINVAL;
1435         }
1436
1437         r = dm_get_device(ti, argv[1], FMODE_READ | FMODE_WRITE, &era->origin_dev);
1438         if (r) {
1439                 ti->error = "Error opening data device";
1440                 era_destroy(era);
1441                 return -EINVAL;
1442         }
1443
1444         r = sscanf(argv[2], "%u%c", &era->sectors_per_block, &dummy);
1445         if (r != 1) {
1446                 ti->error = "Error parsing block size";
1447                 era_destroy(era);
1448                 return -EINVAL;
1449         }
1450
1451         r = dm_set_target_max_io_len(ti, era->sectors_per_block);
1452         if (r) {
1453                 ti->error = "could not set max io len";
1454                 era_destroy(era);
1455                 return -EINVAL;
1456         }
1457
1458         if (!valid_block_size(era->sectors_per_block)) {
1459                 ti->error = "Invalid block size";
1460                 era_destroy(era);
1461                 return -EINVAL;
1462         }
1463         if (era->sectors_per_block & (era->sectors_per_block - 1))
1464                 era->sectors_per_block_shift = -1;
1465         else
1466                 era->sectors_per_block_shift = __ffs(era->sectors_per_block);
1467
1468         md = metadata_open(era->metadata_dev->bdev, era->sectors_per_block, true);
1469         if (IS_ERR(md)) {
1470                 ti->error = "Error reading metadata";
1471                 era_destroy(era);
1472                 return PTR_ERR(md);
1473         }
1474         era->md = md;
1475
1476         era->nr_blocks = calc_nr_blocks(era);
1477
1478         r = metadata_resize(era->md, &era->nr_blocks);
1479         if (r) {
1480                 ti->error = "couldn't resize metadata";
1481                 era_destroy(era);
1482                 return -ENOMEM;
1483         }
1484
1485         era->wq = alloc_ordered_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM);
1486         if (!era->wq) {
1487                 ti->error = "could not create workqueue for metadata object";
1488                 era_destroy(era);
1489                 return -ENOMEM;
1490         }
1491         INIT_WORK(&era->worker, do_work);
1492
1493         spin_lock_init(&era->deferred_lock);
1494         bio_list_init(&era->deferred_bios);
1495
1496         spin_lock_init(&era->rpc_lock);
1497         INIT_LIST_HEAD(&era->rpc_calls);
1498
1499         ti->private = era;
1500         ti->num_flush_bios = 1;
1501         ti->flush_supported = true;
1502
1503         ti->num_discard_bios = 1;
1504
1505         return 0;
1506 }
1507
1508 static void era_dtr(struct dm_target *ti)
1509 {
1510         era_destroy(ti->private);
1511 }
1512
1513 static int era_map(struct dm_target *ti, struct bio *bio)
1514 {
1515         struct era *era = ti->private;
1516         dm_block_t block = get_block(era, bio);
1517
1518         /*
1519          * All bios get remapped to the origin device.  We do this now, but
1520          * it may not get issued until later.  Depending on whether the
1521          * block is marked in this era.
1522          */
1523         remap_to_origin(era, bio);
1524
1525         /*
1526          * REQ_PREFLUSH bios carry no data, so we're not interested in them.
1527          */
1528         if (!(bio->bi_opf & REQ_PREFLUSH) &&
1529             (bio_data_dir(bio) == WRITE) &&
1530             !metadata_current_marked(era->md, block)) {
1531                 defer_bio(era, bio);
1532                 return DM_MAPIO_SUBMITTED;
1533         }
1534
1535         return DM_MAPIO_REMAPPED;
1536 }
1537
1538 static void era_postsuspend(struct dm_target *ti)
1539 {
1540         int r;
1541         struct era *era = ti->private;
1542
1543         r = in_worker0(era, metadata_era_archive);
1544         if (r) {
1545                 DMERR("%s: couldn't archive current era", __func__);
1546                 /* FIXME: fail mode */
1547         }
1548
1549         stop_worker(era);
1550 }
1551
1552 static int era_preresume(struct dm_target *ti)
1553 {
1554         int r;
1555         struct era *era = ti->private;
1556         dm_block_t new_size = calc_nr_blocks(era);
1557
1558         if (era->nr_blocks != new_size) {
1559                 r = in_worker1(era, metadata_resize, &new_size);
1560                 if (r)
1561                         return r;
1562
1563                 era->nr_blocks = new_size;
1564         }
1565
1566         start_worker(era);
1567
1568         r = in_worker0(era, metadata_new_era);
1569         if (r) {
1570                 DMERR("%s: metadata_era_rollover failed", __func__);
1571                 return r;
1572         }
1573
1574         return 0;
1575 }
1576
1577 /*
1578  * Status format:
1579  *
1580  * <metadata block size> <#used metadata blocks>/<#total metadata blocks>
1581  * <current era> <held metadata root | '-'>
1582  */
1583 static void era_status(struct dm_target *ti, status_type_t type,
1584                        unsigned status_flags, char *result, unsigned maxlen)
1585 {
1586         int r;
1587         struct era *era = ti->private;
1588         ssize_t sz = 0;
1589         struct metadata_stats stats;
1590         char buf[BDEVNAME_SIZE];
1591
1592         switch (type) {
1593         case STATUSTYPE_INFO:
1594                 r = in_worker1(era, metadata_get_stats, &stats);
1595                 if (r)
1596                         goto err;
1597
1598                 DMEMIT("%u %llu/%llu %u",
1599                        (unsigned) (DM_ERA_METADATA_BLOCK_SIZE >> SECTOR_SHIFT),
1600                        (unsigned long long) stats.used,
1601                        (unsigned long long) stats.total,
1602                        (unsigned) stats.era);
1603
1604                 if (stats.snap != SUPERBLOCK_LOCATION)
1605                         DMEMIT(" %llu", stats.snap);
1606                 else
1607                         DMEMIT(" -");
1608                 break;
1609
1610         case STATUSTYPE_TABLE:
1611                 format_dev_t(buf, era->metadata_dev->bdev->bd_dev);
1612                 DMEMIT("%s ", buf);
1613                 format_dev_t(buf, era->origin_dev->bdev->bd_dev);
1614                 DMEMIT("%s %u", buf, era->sectors_per_block);
1615                 break;
1616         }
1617
1618         return;
1619
1620 err:
1621         DMEMIT("Error");
1622 }
1623
1624 static int era_message(struct dm_target *ti, unsigned argc, char **argv,
1625                        char *result, unsigned maxlen)
1626 {
1627         struct era *era = ti->private;
1628
1629         if (argc != 1) {
1630                 DMERR("incorrect number of message arguments");
1631                 return -EINVAL;
1632         }
1633
1634         if (!strcasecmp(argv[0], "checkpoint"))
1635                 return in_worker0(era, metadata_checkpoint);
1636
1637         if (!strcasecmp(argv[0], "take_metadata_snap"))
1638                 return in_worker0(era, metadata_take_snap);
1639
1640         if (!strcasecmp(argv[0], "drop_metadata_snap"))
1641                 return in_worker0(era, metadata_drop_snap);
1642
1643         DMERR("unsupported message '%s'", argv[0]);
1644         return -EINVAL;
1645 }
1646
1647 static sector_t get_dev_size(struct dm_dev *dev)
1648 {
1649         return i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT;
1650 }
1651
1652 static int era_iterate_devices(struct dm_target *ti,
1653                                iterate_devices_callout_fn fn, void *data)
1654 {
1655         struct era *era = ti->private;
1656         return fn(ti, era->origin_dev, 0, get_dev_size(era->origin_dev), data);
1657 }
1658
1659 static void era_io_hints(struct dm_target *ti, struct queue_limits *limits)
1660 {
1661         struct era *era = ti->private;
1662         uint64_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;
1663
1664         /*
1665          * If the system-determined stacked limits are compatible with the
1666          * era device's blocksize (io_opt is a factor) do not override them.
1667          */
1668         if (io_opt_sectors < era->sectors_per_block ||
1669             do_div(io_opt_sectors, era->sectors_per_block)) {
1670                 blk_limits_io_min(limits, 0);
1671                 blk_limits_io_opt(limits, era->sectors_per_block << SECTOR_SHIFT);
1672         }
1673 }
1674
1675 /*----------------------------------------------------------------*/
1676
1677 static struct target_type era_target = {
1678         .name = "era",
1679         .version = {1, 0, 0},
1680         .module = THIS_MODULE,
1681         .ctr = era_ctr,
1682         .dtr = era_dtr,
1683         .map = era_map,
1684         .postsuspend = era_postsuspend,
1685         .preresume = era_preresume,
1686         .status = era_status,
1687         .message = era_message,
1688         .iterate_devices = era_iterate_devices,
1689         .io_hints = era_io_hints
1690 };
1691
1692 static int __init dm_era_init(void)
1693 {
1694         int r;
1695
1696         r = dm_register_target(&era_target);
1697         if (r) {
1698                 DMERR("era target registration failed: %d", r);
1699                 return r;
1700         }
1701
1702         return 0;
1703 }
1704
1705 static void __exit dm_era_exit(void)
1706 {
1707         dm_unregister_target(&era_target);
1708 }
1709
1710 module_init(dm_era_init);
1711 module_exit(dm_era_exit);
1712
1713 MODULE_DESCRIPTION(DM_NAME " era target");
1714 MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
1715 MODULE_LICENSE("GPL");