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         ws->bits = NULL;
  51 }
  52
  53 static int setup_on_disk_bitset(struct dm_disk_bitset *info,
  54                                 unsigned nr_bits, dm_block_t *root)
  55 {
  56         int r;
  57
  58         r = dm_bitset_empty(info, root);
  59         if (r)
  60                 return r;
  61
  62         return dm_bitset_resize(info, *root, 0, nr_bits, false, root);
  63 }
  64
  65 static size_t bitset_size(unsigned nr_bits)
  66 {
  67         return sizeof(unsigned long) * dm_div_up(nr_bits, BITS_PER_LONG);
  68 }
  69
  70 /*
  71  * Allocates memory for the in core bitset.
  72  */
  73 static int writeset_alloc(struct writeset *ws, dm_block_t nr_blocks)
  74 {
  75         ws->bits = vzalloc(bitset_size(nr_blocks));
  76         if (!ws->bits) {
  77                 DMERR("%s: couldn't allocate in memory bitset", __func__);
  78                 return -ENOMEM;
  79         }
  80
  81         return 0;
  82 }
  83
  84 /*
  85  * Wipes the in-core bitset, and creates a new on disk bitset.
  86  */
  87 static int writeset_init(struct dm_disk_bitset *info, struct writeset *ws,
  88                          dm_block_t nr_blocks)
  89 {
  90         int r;
  91
  92         memset(ws->bits, 0, bitset_size(nr_blocks));
  93
  94         ws->md.nr_bits = nr_blocks;
  95         r = setup_on_disk_bitset(info, ws->md.nr_bits, &ws->md.root);
  96         if (r) {
  97                 DMERR("%s: setup_on_disk_bitset failed", __func__);
  98                 return r;
  99         }
 100
 101         return 0;
 102 }
 103
 104 static bool writeset_marked(struct writeset *ws, dm_block_t block)
 105 {
 106         return test_bit(block, ws->bits);
 107 }
 108
 109 static int writeset_marked_on_disk(struct dm_disk_bitset *info,
 110                                    struct writeset_metadata *m, dm_block_t block,
 111                                    bool *result)
 112 {
 113         dm_block_t old = m->root;
 114
 115         /*
 116          * The bitset was flushed when it was archived, so we know there'll
 117          * be no change to the root.
 118          */
 119         int r = dm_bitset_test_bit(info, m->root, block, &m->root, result);
 120         if (r) {
 121                 DMERR("%s: dm_bitset_test_bit failed", __func__);
 122                 return r;
 123         }
 124
 125         BUG_ON(m->root != old);
 126
 127         return r;
 128 }
 129
 130 /*
 131  * Returns < 0 on error, 0 if the bit wasn't previously set, 1 if it was.
 132  */
 133 static int writeset_test_and_set(struct dm_disk_bitset *info,
 134                                  struct writeset *ws, uint32_t block)
 135 {
 136         int r;
 137
 138         if (!test_bit(block, ws->bits)) {
 139                 r = dm_bitset_set_bit(info, ws->md.root, block, &ws->md.root);
 140                 if (r) {
 141                         /* FIXME: fail mode */
 142                         return r;
 143                 }
 144
 145                 return 0;
 146         }
 147
 148         return 1;
 149 }
 150
 151 /*----------------------------------------------------------------
 152  * On disk metadata layout
 153  *--------------------------------------------------------------*/
 154 #define SPACE_MAP_ROOT_SIZE 128
 155 #define UUID_LEN 16
 156
 157 struct writeset_disk {
 158         __le32 nr_bits;
 159         __le64 root;
 160 } __packed;
 161
 162 struct superblock_disk {
 163         __le32 csum;
 164         __le32 flags;
 165         __le64 blocknr;
 166
 167         __u8 uuid[UUID_LEN];
 168         __le64 magic;
 169         __le32 version;
 170
 171         __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
 172
 173         __le32 data_block_size;
 174         __le32 metadata_block_size;
 175         __le32 nr_blocks;
 176
 177         __le32 current_era;
 178         struct writeset_disk current_writeset;
 179
 180         /*
 181          * Only these two fields are valid within the metadata snapshot.
 182          */
 183         __le64 writeset_tree_root;
 184         __le64 era_array_root;
 185
 186         __le64 metadata_snap;
 187 } __packed;
 188
 189 /*----------------------------------------------------------------
 190  * Superblock validation
 191  *--------------------------------------------------------------*/
 192 static void sb_prepare_for_write(struct dm_block_validator *v,
 193                                  struct dm_block *b,
 194                                  size_t sb_block_size)
 195 {
 196         struct superblock_disk *disk = dm_block_data(b);
 197
 198         disk->blocknr = cpu_to_le64(dm_block_location(b));
 199         disk->csum = cpu_to_le32(dm_bm_checksum(&disk->flags,
 200                                                 sb_block_size - sizeof(__le32),
 201                                                 SUPERBLOCK_CSUM_XOR));
 202 }
 203
 204 static int check_metadata_version(struct superblock_disk *disk)
 205 {
 206         uint32_t metadata_version = le32_to_cpu(disk->version);
 207         if (metadata_version < MIN_ERA_VERSION || metadata_version > MAX_ERA_VERSION) {
 208                 DMERR("Era metadata version %u found, but only versions between %u and %u supported.",
 209                       metadata_version, MIN_ERA_VERSION, MAX_ERA_VERSION);
 210                 return -EINVAL;
 211         }
 212
 213         return 0;
 214 }
 215
 216 static int sb_check(struct dm_block_validator *v,
 217                     struct dm_block *b,
 218                     size_t sb_block_size)
 219 {
 220         struct superblock_disk *disk = dm_block_data(b);
 221         __le32 csum_le;
 222
 223         if (dm_block_location(b) != le64_to_cpu(disk->blocknr)) {
 224                 DMERR("sb_check failed: blocknr %llu: wanted %llu",
 225                       le64_to_cpu(disk->blocknr),
 226                       (unsigned long long)dm_block_location(b));
 227                 return -ENOTBLK;
 228         }
 229
 230         if (le64_to_cpu(disk->magic) != SUPERBLOCK_MAGIC) {
 231                 DMERR("sb_check failed: magic %llu: wanted %llu",
 232                       le64_to_cpu(disk->magic),
 233                       (unsigned long long) SUPERBLOCK_MAGIC);
 234                 return -EILSEQ;
 235         }
 236
 237         csum_le = cpu_to_le32(dm_bm_checksum(&disk->flags,
 238                                              sb_block_size - sizeof(__le32),
 239                                              SUPERBLOCK_CSUM_XOR));
 240         if (csum_le != disk->csum) {
 241                 DMERR("sb_check failed: csum %u: wanted %u",
 242                       le32_to_cpu(csum_le), le32_to_cpu(disk->csum));
 243                 return -EILSEQ;
 244         }
 245
 246         return check_metadata_version(disk);
 247 }
 248
 249 static struct dm_block_validator sb_validator = {
 250         .name = "superblock",
 251         .prepare_for_write = sb_prepare_for_write,
 252         .check = sb_check
 253 };
 254
 255 /*----------------------------------------------------------------
 256  * Low level metadata handling
 257  *--------------------------------------------------------------*/
 258 #define DM_ERA_METADATA_BLOCK_SIZE 4096
 259 #define ERA_MAX_CONCURRENT_LOCKS 5
 260
 261 struct era_metadata {
 262         struct block_device *bdev;
 263         struct dm_block_manager *bm;
 264         struct dm_space_map *sm;
 265         struct dm_transaction_manager *tm;
 266
 267         dm_block_t block_size;
 268         uint32_t nr_blocks;
 269
 270         uint32_t current_era;
 271
 272         /*
 273          * We preallocate 2 writesets.  When an era rolls over we
 274          * switch between them. This means the allocation is done at
 275          * preresume time, rather than on the io path.
 276          */
 277         struct writeset writesets[2];
 278         struct writeset *current_writeset;
 279
 280         dm_block_t writeset_tree_root;
 281         dm_block_t era_array_root;
 282
 283         struct dm_disk_bitset bitset_info;
 284         struct dm_btree_info writeset_tree_info;
 285         struct dm_array_info era_array_info;
 286
 287         dm_block_t metadata_snap;
 288
 289         /*
 290          * A flag that is set whenever a writeset has been archived.
 291          */
 292         bool archived_writesets;
 293
 294         /*
 295          * Reading the space map root can fail, so we read it into this
 296          * buffer before the superblock is locked and updated.
 297          */
 298         __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
 299 };
 300
 301 static int superblock_read_lock(struct era_metadata *md,
 302                                 struct dm_block **sblock)
 303 {
 304         return dm_bm_read_lock(md->bm, SUPERBLOCK_LOCATION,
 305                                &sb_validator, sblock);
 306 }
 307
 308 static int superblock_lock_zero(struct era_metadata *md,
 309                                 struct dm_block **sblock)
 310 {
 311         return dm_bm_write_lock_zero(md->bm, SUPERBLOCK_LOCATION,
 312                                      &sb_validator, sblock);
 313 }
 314
 315 static int superblock_lock(struct era_metadata *md,
 316                            struct dm_block **sblock)
 317 {
 318         return dm_bm_write_lock(md->bm, SUPERBLOCK_LOCATION,
 319                                 &sb_validator, sblock);
 320 }
 321
 322 /* FIXME: duplication with cache and thin */
 323 static int superblock_all_zeroes(struct dm_block_manager *bm, bool *result)
 324 {
 325         int r;
 326         unsigned i;
 327         struct dm_block *b;
 328         __le64 *data_le, zero = cpu_to_le64(0);
 329         unsigned sb_block_size = dm_bm_block_size(bm) / sizeof(__le64);
 330
 331         /*
 332          * We can't use a validator here - it may be all zeroes.
 333          */
 334         r = dm_bm_read_lock(bm, SUPERBLOCK_LOCATION, NULL, &b);
 335         if (r)
 336                 return r;
 337
 338         data_le = dm_block_data(b);
 339         *result = true;
 340         for (i = 0; i < sb_block_size; i++) {
 341                 if (data_le[i] != zero) {
 342                         *result = false;
 343                         break;
 344                 }
 345         }
 346
 347         dm_bm_unlock(b);
 348
 349         return 0;
 350 }
 351
 352 /*----------------------------------------------------------------*/
 353
 354 static void ws_pack(const struct writeset_metadata *core, struct writeset_disk *disk)
 355 {
 356         disk->nr_bits = cpu_to_le32(core->nr_bits);
 357         disk->root = cpu_to_le64(core->root);
 358 }
 359
 360 static void ws_unpack(const struct writeset_disk *disk, struct writeset_metadata *core)
 361 {
 362         core->nr_bits = le32_to_cpu(disk->nr_bits);
 363         core->root = le64_to_cpu(disk->root);
 364 }
 365
 366 static void ws_inc(void *context, const void *value, unsigned count)
 367 {
 368         struct era_metadata *md = context;
 369         struct writeset_disk ws_d;
 370         dm_block_t b;
 371         unsigned i;
 372
 373         for (i = 0; i < count; i++) {
 374                 memcpy(&ws_d, value + (i * sizeof(ws_d)), sizeof(ws_d));
 375                 b = le64_to_cpu(ws_d.root);
 376                 dm_tm_inc(md->tm, b);
 377         }
 378 }
 379
 380 static void ws_dec(void *context, const void *value, unsigned count)
 381 {
 382         struct era_metadata *md = context;
 383         struct writeset_disk ws_d;
 384         dm_block_t b;
 385         unsigned i;
 386
 387         for (i = 0; i < count; i++) {
 388                 memcpy(&ws_d, value + (i * sizeof(ws_d)), sizeof(ws_d));
 389                 b = le64_to_cpu(ws_d.root);
 390                 dm_bitset_del(&md->bitset_info, b);
 391         }
 392 }
 393
 394 static int ws_eq(void *context, const void *value1, const void *value2)
 395 {
 396         return !memcmp(value1, value2, sizeof(struct writeset_disk));
 397 }
 398
 399 /*----------------------------------------------------------------*/
 400
 401 static void setup_writeset_tree_info(struct era_metadata *md)
 402 {
 403         struct dm_btree_value_type *vt = &md->writeset_tree_info.value_type;
 404         md->writeset_tree_info.tm = md->tm;
 405         md->writeset_tree_info.levels = 1;
 406         vt->context = md;
 407         vt->size = sizeof(struct writeset_disk);
 408         vt->inc = ws_inc;
 409         vt->dec = ws_dec;
 410         vt->equal = ws_eq;
 411 }
 412
 413 static void setup_era_array_info(struct era_metadata *md)
 414
 415 {
 416         struct dm_btree_value_type vt;
 417         vt.context = NULL;
 418         vt.size = sizeof(__le32);
 419         vt.inc = NULL;
 420         vt.dec = NULL;
 421         vt.equal = NULL;
 422
 423         dm_array_info_init(&md->era_array_info, md->tm, &vt);
 424 }
 425
 426 static void setup_infos(struct era_metadata *md)
 427 {
 428         dm_disk_bitset_init(md->tm, &md->bitset_info);
 429         setup_writeset_tree_info(md);
 430         setup_era_array_info(md);
 431 }
 432
 433 /*----------------------------------------------------------------*/
 434
 435 static int create_fresh_metadata(struct era_metadata *md)
 436 {
 437         int r;
 438
 439         r = dm_tm_create_with_sm(md->bm, SUPERBLOCK_LOCATION,
 440                                  &md->tm, &md->sm);
 441         if (r < 0) {
 442                 DMERR("dm_tm_create_with_sm failed");
 443                 return r;
 444         }
 445
 446         setup_infos(md);
 447
 448         r = dm_btree_empty(&md->writeset_tree_info, &md->writeset_tree_root);
 449         if (r) {
 450                 DMERR("couldn't create new writeset tree");
 451                 goto bad;
 452         }
 453
 454         r = dm_array_empty(&md->era_array_info, &md->era_array_root);
 455         if (r) {
 456                 DMERR("couldn't create era array");
 457                 goto bad;
 458         }
 459
 460         return 0;
 461
 462 bad:
 463         dm_sm_destroy(md->sm);
 464         dm_tm_destroy(md->tm);
 465
 466         return r;
 467 }
 468
 469 static int save_sm_root(struct era_metadata *md)
 470 {
 471         int r;
 472         size_t metadata_len;
 473
 474         r = dm_sm_root_size(md->sm, &metadata_len);
 475         if (r < 0)
 476                 return r;
 477
 478         return dm_sm_copy_root(md->sm, &md->metadata_space_map_root,
 479                                metadata_len);
 480 }
 481
 482 static void copy_sm_root(struct era_metadata *md, struct superblock_disk *disk)
 483 {
 484         memcpy(&disk->metadata_space_map_root,
 485                &md->metadata_space_map_root,
 486                sizeof(md->metadata_space_map_root));
 487 }
 488
 489 /*
 490  * Writes a superblock, including the static fields that don't get updated
 491  * with every commit (possible optimisation here).  'md' should be fully
 492  * constructed when this is called.
 493  */
 494 static void prepare_superblock(struct era_metadata *md, struct superblock_disk *disk)
 495 {
 496         disk->magic = cpu_to_le64(SUPERBLOCK_MAGIC);
 497         disk->flags = cpu_to_le32(0ul);
 498
 499         /* FIXME: can't keep blanking the uuid (uuid is currently unused though) */
 500         memset(disk->uuid, 0, sizeof(disk->uuid));
 501         disk->version = cpu_to_le32(MAX_ERA_VERSION);
 502
 503         copy_sm_root(md, disk);
 504
 505         disk->data_block_size = cpu_to_le32(md->block_size);
 506         disk->metadata_block_size = cpu_to_le32(DM_ERA_METADATA_BLOCK_SIZE >> SECTOR_SHIFT);
 507         disk->nr_blocks = cpu_to_le32(md->nr_blocks);
 508         disk->current_era = cpu_to_le32(md->current_era);
 509
 510         ws_pack(&md->current_writeset->md, &disk->current_writeset);
 511         disk->writeset_tree_root = cpu_to_le64(md->writeset_tree_root);
 512         disk->era_array_root = cpu_to_le64(md->era_array_root);
 513         disk->metadata_snap = cpu_to_le64(md->metadata_snap);
 514 }
 515
 516 static int write_superblock(struct era_metadata *md)
 517 {
 518         int r;
 519         struct dm_block *sblock;
 520         struct superblock_disk *disk;
 521
 522         r = save_sm_root(md);
 523         if (r) {
 524                 DMERR("%s: save_sm_root failed", __func__);
 525                 return r;
 526         }
 527
 528         r = superblock_lock_zero(md, &sblock);
 529         if (r)
 530                 return r;
 531
 532         disk = dm_block_data(sblock);
 533         prepare_superblock(md, disk);
 534
 535         return dm_tm_commit(md->tm, sblock);
 536 }
 537
 538 /*
 539  * Assumes block_size and the infos are set.
 540  */
 541 static int format_metadata(struct era_metadata *md)
 542 {
 543         int r;
 544
 545         r = create_fresh_metadata(md);
 546         if (r)
 547                 return r;
 548
 549         r = write_superblock(md);
 550         if (r) {
 551                 dm_sm_destroy(md->sm);
 552                 dm_tm_destroy(md->tm);
 553                 return r;
 554         }
 555
 556         return 0;
 557 }
 558
 559 static int open_metadata(struct era_metadata *md)
 560 {
 561         int r;
 562         struct dm_block *sblock;
 563         struct superblock_disk *disk;
 564
 565         r = superblock_read_lock(md, &sblock);
 566         if (r) {
 567                 DMERR("couldn't read_lock superblock");
 568                 return r;
 569         }
 570
 571         disk = dm_block_data(sblock);
 572
 573         /* Verify the data block size hasn't changed */
 574         if (le32_to_cpu(disk->data_block_size) != md->block_size) {
 575                 DMERR("changing the data block size (from %u to %llu) is not supported",
 576                       le32_to_cpu(disk->data_block_size), md->block_size);
 577                 r = -EINVAL;
 578                 goto bad;
 579         }
 580
 581         r = dm_tm_open_with_sm(md->bm, SUPERBLOCK_LOCATION,
 582                                disk->metadata_space_map_root,
 583                                sizeof(disk->metadata_space_map_root),
 584                                &md->tm, &md->sm);
 585         if (r) {
 586                 DMERR("dm_tm_open_with_sm failed");
 587                 goto bad;
 588         }
 589
 590         setup_infos(md);
 591
 592         md->nr_blocks = le32_to_cpu(disk->nr_blocks);
 593         md->current_era = le32_to_cpu(disk->current_era);
 594
 595         ws_unpack(&disk->current_writeset, &md->current_writeset->md);
 596         md->writeset_tree_root = le64_to_cpu(disk->writeset_tree_root);
 597         md->era_array_root = le64_to_cpu(disk->era_array_root);
 598         md->metadata_snap = le64_to_cpu(disk->metadata_snap);
 599         md->archived_writesets = true;
 600
 601         dm_bm_unlock(sblock);
 602
 603         return 0;
 604
 605 bad:
 606         dm_bm_unlock(sblock);
 607         return r;
 608 }
 609
 610 static int open_or_format_metadata(struct era_metadata *md,
 611                                    bool may_format)
 612 {
 613         int r;
 614         bool unformatted = false;
 615
 616         r = superblock_all_zeroes(md->bm, &unformatted);
 617         if (r)
 618                 return r;
 619
 620         if (unformatted)
 621                 return may_format ? format_metadata(md) : -EPERM;
 622
 623         return open_metadata(md);
 624 }
 625
 626 static int create_persistent_data_objects(struct era_metadata *md,
 627                                           bool may_format)
 628 {
 629         int r;
 630
 631         md->bm = dm_block_manager_create(md->bdev, DM_ERA_METADATA_BLOCK_SIZE,
 632                                          ERA_MAX_CONCURRENT_LOCKS);
 633         if (IS_ERR(md->bm)) {
 634                 DMERR("could not create block manager");
 635                 return PTR_ERR(md->bm);
 636         }
 637
 638         r = open_or_format_metadata(md, may_format);
 639         if (r)
 640                 dm_block_manager_destroy(md->bm);
 641
 642         return r;
 643 }
 644
 645 static void destroy_persistent_data_objects(struct era_metadata *md)
 646 {
 647         dm_sm_destroy(md->sm);
 648         dm_tm_destroy(md->tm);
 649         dm_block_manager_destroy(md->bm);
 650 }
 651
 652 /*
 653  * This waits until all era_map threads have picked up the new filter.
 654  */
 655 static void swap_writeset(struct era_metadata *md, struct writeset *new_writeset)
 656 {
 657         rcu_assign_pointer(md->current_writeset, new_writeset);
 658         synchronize_rcu();
 659 }
 660
 661 /*----------------------------------------------------------------
 662  * Writesets get 'digested' into the main era array.
 663  *
 664  * We're using a coroutine here so the worker thread can do the digestion,
 665  * thus avoiding synchronisation of the metadata.  Digesting a whole
 666  * writeset in one go would cause too much latency.
 667  *--------------------------------------------------------------*/
 668 struct digest {
 669         uint32_t era;
 670         unsigned nr_bits, current_bit;
 671         struct writeset_metadata writeset;
 672         __le32 value;
 673         struct dm_disk_bitset info;
 674
 675         int (*step)(struct era_metadata *, struct digest *);
 676 };
 677
 678 static int metadata_digest_lookup_writeset(struct era_metadata *md,
 679                                            struct digest *d);
 680
 681 static int metadata_digest_remove_writeset(struct era_metadata *md,
 682                                            struct digest *d)
 683 {
 684         int r;
 685         uint64_t key = d->era;
 686
 687         r = dm_btree_remove(&md->writeset_tree_info, md->writeset_tree_root,
 688                             &key, &md->writeset_tree_root);
 689         if (r) {
 690                 DMERR("%s: dm_btree_remove failed", __func__);
 691                 return r;
 692         }
 693
 694         d->step = metadata_digest_lookup_writeset;
 695         return 0;
 696 }
 697
 698 #define INSERTS_PER_STEP 100
 699
 700 static int metadata_digest_transcribe_writeset(struct era_metadata *md,
 701                                                struct digest *d)
 702 {
 703         int r;
 704         bool marked;
 705         unsigned b, e = min(d->current_bit + INSERTS_PER_STEP, d->nr_bits);
 706
 707         for (b = d->current_bit; b < e; b++) {
 708                 r = writeset_marked_on_disk(&d->info, &d->writeset, b, &marked);
 709                 if (r) {
 710                         DMERR("%s: writeset_marked_on_disk failed", __func__);
 711                         return r;
 712                 }
 713
 714                 if (!marked)
 715                         continue;
 716
 717                 __dm_bless_for_disk(&d->value);
 718                 r = dm_array_set_value(&md->era_array_info, md->era_array_root,
 719                                        b, &d->value, &md->era_array_root);
 720                 if (r) {
 721                         DMERR("%s: dm_array_set_value failed", __func__);
 722                         return r;
 723                 }
 724         }
 725
 726         if (b == d->nr_bits)
 727                 d->step = metadata_digest_remove_writeset;
 728         else
 729                 d->current_bit = b;
 730
 731         return 0;
 732 }
 733
 734 static int metadata_digest_lookup_writeset(struct era_metadata *md,
 735                                            struct digest *d)
 736 {
 737         int r;
 738         uint64_t key;
 739         struct writeset_disk disk;
 740
 741         r = dm_btree_find_lowest_key(&md->writeset_tree_info,
 742                                      md->writeset_tree_root, &key);
 743         if (r < 0)
 744                 return r;
 745
 746         d->era = key;
 747
 748         r = dm_btree_lookup(&md->writeset_tree_info,
 749                             md->writeset_tree_root, &key, &disk);
 750         if (r) {
 751                 if (r == -ENODATA) {
 752                         d->step = NULL;
 753                         return 0;
 754                 }
 755
 756                 DMERR("%s: dm_btree_lookup failed", __func__);
 757                 return r;
 758         }
 759
 760         ws_unpack(&disk, &d->writeset);
 761         d->value = cpu_to_le32(key);
 762
 763         /*
 764          * We initialise another bitset info to avoid any caching side effects
 765          * with the previous one.
 766          */
 767         dm_disk_bitset_init(md->tm, &d->info);
 768
 769         d->nr_bits = min(d->writeset.nr_bits, md->nr_blocks);
 770         d->current_bit = 0;
 771         d->step = metadata_digest_transcribe_writeset;
 772
 773         return 0;
 774 }
 775
 776 static int metadata_digest_start(struct era_metadata *md, struct digest *d)
 777 {
 778         if (d->step)
 779                 return 0;
 780
 781         memset(d, 0, sizeof(*d));
 782         d->step = metadata_digest_lookup_writeset;
 783
 784         return 0;
 785 }
 786
 787 /*----------------------------------------------------------------
 788  * High level metadata interface.  Target methods should use these, and not
 789  * the lower level ones.
 790  *--------------------------------------------------------------*/
 791 static struct era_metadata *metadata_open(struct block_device *bdev,
 792                                           sector_t block_size,
 793                                           bool may_format)
 794 {
 795         int r;
 796         struct era_metadata *md = kzalloc(sizeof(*md), GFP_KERNEL);
 797
 798         if (!md)
 799                 return NULL;
 800
 801         md->bdev = bdev;
 802         md->block_size = block_size;
 803
 804         md->writesets[0].md.root = INVALID_WRITESET_ROOT;
 805         md->writesets[1].md.root = INVALID_WRITESET_ROOT;
 806         md->current_writeset = &md->writesets[0];
 807
 808         r = create_persistent_data_objects(md, may_format);
 809         if (r) {
 810                 kfree(md);
 811                 return ERR_PTR(r);
 812         }
 813
 814         return md;
 815 }
 816
 817 static void metadata_close(struct era_metadata *md)
 818 {
 819         writeset_free(&md->writesets[0]);
 820         writeset_free(&md->writesets[1]);
 821         destroy_persistent_data_objects(md);
 822         kfree(md);
 823 }
 824
 825 static bool valid_nr_blocks(dm_block_t n)
 826 {
 827         /*
 828          * dm_bitset restricts us to 2^32.  test_bit & co. restrict us
 829          * further to 2^31 - 1
 830          */
 831         return n < (1ull << 31);
 832 }
 833
 834 static int metadata_resize(struct era_metadata *md, void *arg)
 835 {
 836         int r;
 837         dm_block_t *new_size = arg;
 838         __le32 value;
 839
 840         if (!valid_nr_blocks(*new_size)) {
 841                 DMERR("Invalid number of origin blocks %llu",
 842                       (unsigned long long) *new_size);
 843                 return -EINVAL;
 844         }
 845
 846         writeset_free(&md->writesets[0]);
 847         writeset_free(&md->writesets[1]);
 848
 849         r = writeset_alloc(&md->writesets[0], *new_size);
 850         if (r) {
 851                 DMERR("%s: writeset_alloc failed for writeset 0", __func__);
 852                 return r;
 853         }
 854
 855         r = writeset_alloc(&md->writesets[1], *new_size);
 856         if (r) {
 857                 DMERR("%s: writeset_alloc failed for writeset 1", __func__);
 858                 writeset_free(&md->writesets[0]);
 859                 return r;
 860         }
 861
 862         value = cpu_to_le32(0u);
 863         __dm_bless_for_disk(&value);
 864         r = dm_array_resize(&md->era_array_info, md->era_array_root,
 865                             md->nr_blocks, *new_size,
 866                             &value, &md->era_array_root);
 867         if (r) {
 868                 DMERR("%s: dm_array_resize failed", __func__);
 869                 writeset_free(&md->writesets[0]);
 870                 writeset_free(&md->writesets[1]);
 871                 return r;
 872         }
 873
 874         md->nr_blocks = *new_size;
 875         return 0;
 876 }
 877
 878 static int metadata_era_archive(struct era_metadata *md)
 879 {
 880         int r;
 881         uint64_t keys[1];
 882         struct writeset_disk value;
 883
 884         r = dm_bitset_flush(&md->bitset_info, md->current_writeset->md.root,
 885                             &md->current_writeset->md.root);
 886         if (r) {
 887                 DMERR("%s: dm_bitset_flush failed", __func__);
 888                 return r;
 889         }
 890
 891         ws_pack(&md->current_writeset->md, &value);
 892
 893         keys[0] = md->current_era;
 894         __dm_bless_for_disk(&value);
 895         r = dm_btree_insert(&md->writeset_tree_info, md->writeset_tree_root,
 896                             keys, &value, &md->writeset_tree_root);
 897         if (r) {
 898                 DMERR("%s: couldn't insert writeset into btree", __func__);
 899                 /* FIXME: fail mode */
 900                 return r;
 901         }
 902
 903         md->current_writeset->md.root = INVALID_WRITESET_ROOT;
 904         md->archived_writesets = true;
 905
 906         return 0;
 907 }
 908
 909 static struct writeset *next_writeset(struct era_metadata *md)
 910 {
 911         return (md->current_writeset == &md->writesets[0]) ?
 912                 &md->writesets[1] : &md->writesets[0];
 913 }
 914
 915 static int metadata_new_era(struct era_metadata *md)
 916 {
 917         int r;
 918         struct writeset *new_writeset = next_writeset(md);
 919
 920         r = writeset_init(&md->bitset_info, new_writeset, md->nr_blocks);
 921         if (r) {
 922                 DMERR("%s: writeset_init failed", __func__);
 923                 return r;
 924         }
 925
 926         swap_writeset(md, new_writeset);
 927         md->current_era++;
 928
 929         return 0;
 930 }
 931
 932 static int metadata_era_rollover(struct era_metadata *md)
 933 {
 934         int r;
 935
 936         if (md->current_writeset->md.root != INVALID_WRITESET_ROOT) {
 937                 r = metadata_era_archive(md);
 938                 if (r) {
 939                         DMERR("%s: metadata_archive_era failed", __func__);
 940                         /* FIXME: fail mode? */
 941                         return r;
 942                 }
 943         }
 944
 945         r = metadata_new_era(md);
 946         if (r) {
 947                 DMERR("%s: new era failed", __func__);
 948                 /* FIXME: fail mode */
 949                 return r;
 950         }
 951
 952         return 0;
 953 }
 954
 955 static bool metadata_current_marked(struct era_metadata *md, dm_block_t block)
 956 {
 957         bool r;
 958         struct writeset *ws;
 959
 960         rcu_read_lock();
 961         ws = rcu_dereference(md->current_writeset);
 962         r = writeset_marked(ws, block);
 963         rcu_read_unlock();
 964
 965         return r;
 966 }
 967
 968 static int metadata_commit(struct era_metadata *md)
 969 {
 970         int r;
 971         struct dm_block *sblock;
 972
 973         if (md->current_writeset->md.root != INVALID_WRITESET_ROOT) {
 974                 r = dm_bitset_flush(&md->bitset_info, md->current_writeset->md.root,
 975                                     &md->current_writeset->md.root);
 976                 if (r) {
 977                         DMERR("%s: bitset flush failed", __func__);
 978                         return r;
 979                 }
 980         }
 981
 982         r = dm_tm_pre_commit(md->tm);
 983         if (r) {
 984                 DMERR("%s: pre commit failed", __func__);
 985                 return r;
 986         }
 987
 988         r = save_sm_root(md);
 989         if (r) {
 990                 DMERR("%s: save_sm_root failed", __func__);
 991                 return r;
 992         }
 993
 994         r = superblock_lock(md, &sblock);
 995         if (r) {
 996                 DMERR("%s: superblock lock failed", __func__);
 997                 return r;
 998         }
 999
1000         prepare_superblock(md, dm_block_data(sblock));
1001
1002         return dm_tm_commit(md->tm, sblock);
1003 }
1004
1005 static int metadata_checkpoint(struct era_metadata *md)
1006 {
1007         /*
1008          * For now we just rollover, but later I want to put a check in to
1009          * avoid this if the filter is still pretty fresh.
1010          */
1011         return metadata_era_rollover(md);
1012 }
1013
1014 /*
1015  * Metadata snapshots allow userland to access era data.
1016  */
1017 static int metadata_take_snap(struct era_metadata *md)
1018 {
1019         int r, inc;
1020         struct dm_block *clone;
1021
1022         if (md->metadata_snap != SUPERBLOCK_LOCATION) {
1023                 DMERR("%s: metadata snapshot already exists", __func__);
1024                 return -EINVAL;
1025         }
1026
1027         r = metadata_era_rollover(md);
1028         if (r) {
1029                 DMERR("%s: era rollover failed", __func__);
1030                 return r;
1031         }
1032
1033         r = metadata_commit(md);
1034         if (r) {
1035                 DMERR("%s: pre commit failed", __func__);
1036                 return r;
1037         }
1038
1039         r = dm_sm_inc_block(md->sm, SUPERBLOCK_LOCATION);
1040         if (r) {
1041                 DMERR("%s: couldn't increment superblock", __func__);
1042                 return r;
1043         }
1044
1045         r = dm_tm_shadow_block(md->tm, SUPERBLOCK_LOCATION,
1046                                &sb_validator, &clone, &inc);
1047         if (r) {
1048                 DMERR("%s: couldn't shadow superblock", __func__);
1049                 dm_sm_dec_block(md->sm, SUPERBLOCK_LOCATION);
1050                 return r;
1051         }
1052         BUG_ON(!inc);
1053
1054         r = dm_sm_inc_block(md->sm, md->writeset_tree_root);
1055         if (r) {
1056                 DMERR("%s: couldn't inc writeset tree root", __func__);
1057                 dm_tm_unlock(md->tm, clone);
1058                 return r;
1059         }
1060
1061         r = dm_sm_inc_block(md->sm, md->era_array_root);
1062         if (r) {
1063                 DMERR("%s: couldn't inc era tree root", __func__);
1064                 dm_sm_dec_block(md->sm, md->writeset_tree_root);
1065                 dm_tm_unlock(md->tm, clone);
1066                 return r;
1067         }
1068
1069         md->metadata_snap = dm_block_location(clone);
1070
1071         dm_tm_unlock(md->tm, clone);
1072
1073         return 0;
1074 }
1075
1076 static int metadata_drop_snap(struct era_metadata *md)
1077 {
1078         int r;
1079         dm_block_t location;
1080         struct dm_block *clone;
1081         struct superblock_disk *disk;
1082
1083         if (md->metadata_snap == SUPERBLOCK_LOCATION) {
1084                 DMERR("%s: no snap to drop", __func__);
1085                 return -EINVAL;
1086         }
1087
1088         r = dm_tm_read_lock(md->tm, md->metadata_snap, &sb_validator, &clone);
1089         if (r) {
1090                 DMERR("%s: couldn't read lock superblock clone", __func__);
1091                 return r;
1092         }
1093
1094         /*
1095          * Whatever happens now we'll commit with no record of the metadata
1096          * snap.
1097          */
1098         md->metadata_snap = SUPERBLOCK_LOCATION;
1099
1100         disk = dm_block_data(clone);
1101         r = dm_btree_del(&md->writeset_tree_info,
1102                          le64_to_cpu(disk->writeset_tree_root));
1103         if (r) {
1104                 DMERR("%s: error deleting writeset tree clone", __func__);
1105                 dm_tm_unlock(md->tm, clone);
1106                 return r;
1107         }
1108
1109         r = dm_array_del(&md->era_array_info, le64_to_cpu(disk->era_array_root));
1110         if (r) {
1111                 DMERR("%s: error deleting era array clone", __func__);
1112                 dm_tm_unlock(md->tm, clone);
1113                 return r;
1114         }
1115
1116         location = dm_block_location(clone);
1117         dm_tm_unlock(md->tm, clone);
1118
1119         return dm_sm_dec_block(md->sm, location);
1120 }
1121
1122 struct metadata_stats {
1123         dm_block_t used;
1124         dm_block_t total;
1125         dm_block_t snap;
1126         uint32_t era;
1127 };
1128
1129 static int metadata_get_stats(struct era_metadata *md, void *ptr)
1130 {
1131         int r;
1132         struct metadata_stats *s = ptr;
1133         dm_block_t nr_free, nr_total;
1134
1135         r = dm_sm_get_nr_free(md->sm, &nr_free);
1136         if (r) {
1137                 DMERR("dm_sm_get_nr_free returned %d", r);
1138                 return r;
1139         }
1140
1141         r = dm_sm_get_nr_blocks(md->sm, &nr_total);
1142         if (r) {
1143                 DMERR("dm_pool_get_metadata_dev_size returned %d", r);
1144                 return r;
1145         }
1146
1147         s->used = nr_total - nr_free;
1148         s->total = nr_total;
1149         s->snap = md->metadata_snap;
1150         s->era = md->current_era;
1151
1152         return 0;
1153 }
1154
1155 /*----------------------------------------------------------------*/
1156
1157 struct era {
1158         struct dm_target *ti;
1159
1160         struct dm_dev *metadata_dev;
1161         struct dm_dev *origin_dev;
1162
1163         dm_block_t nr_blocks;
1164         uint32_t sectors_per_block;
1165         int sectors_per_block_shift;
1166         struct era_metadata *md;
1167
1168         struct workqueue_struct *wq;
1169         struct work_struct worker;
1170
1171         spinlock_t deferred_lock;
1172         struct bio_list deferred_bios;
1173
1174         spinlock_t rpc_lock;
1175         struct list_head rpc_calls;
1176
1177         struct digest digest;
1178         atomic_t suspended;
1179 };
1180
1181 struct rpc {
1182         struct list_head list;
1183
1184         int (*fn0)(struct era_metadata *);
1185         int (*fn1)(struct era_metadata *, void *);
1186         void *arg;
1187         int result;
1188
1189         struct completion complete;
1190 };
1191
1192 /*----------------------------------------------------------------
1193  * Remapping.
1194  *---------------------------------------------------------------*/
1195 static bool block_size_is_power_of_two(struct era *era)
1196 {
1197         return era->sectors_per_block_shift >= 0;
1198 }
1199
1200 static dm_block_t get_block(struct era *era, struct bio *bio)
1201 {
1202         sector_t block_nr = bio->bi_iter.bi_sector;
1203
1204         if (!block_size_is_power_of_two(era))
1205                 (void) sector_div(block_nr, era->sectors_per_block);
1206         else
1207                 block_nr >>= era->sectors_per_block_shift;
1208
1209         return block_nr;
1210 }
1211
1212 static void remap_to_origin(struct era *era, struct bio *bio)
1213 {
1214         bio_set_dev(bio, era->origin_dev->bdev);
1215 }
1216
1217 /*----------------------------------------------------------------
1218  * Worker thread
1219  *--------------------------------------------------------------*/
1220 static void wake_worker(struct era *era)
1221 {
1222         if (!atomic_read(&era->suspended))
1223                 queue_work(era->wq, &era->worker);
1224 }
1225
1226 static void process_old_eras(struct era *era)
1227 {
1228         int r;
1229
1230         if (!era->digest.step)
1231                 return;
1232
1233         r = era->digest.step(era->md, &era->digest);
1234         if (r < 0) {
1235                 DMERR("%s: digest step failed, stopping digestion", __func__);
1236                 era->digest.step = NULL;
1237
1238         } else if (era->digest.step)
1239                 wake_worker(era);
1240 }
1241
1242 static void process_deferred_bios(struct era *era)
1243 {
1244         int r;
1245         struct bio_list deferred_bios, marked_bios;
1246         struct bio *bio;
1247         struct blk_plug plug;
1248         bool commit_needed = false;
1249         bool failed = false;
1250         struct writeset *ws = era->md->current_writeset;
1251
1252         bio_list_init(&deferred_bios);
1253         bio_list_init(&marked_bios);
1254
1255         spin_lock(&era->deferred_lock);
1256         bio_list_merge(&deferred_bios, &era->deferred_bios);
1257         bio_list_init(&era->deferred_bios);
1258         spin_unlock(&era->deferred_lock);
1259
1260         if (bio_list_empty(&deferred_bios))
1261                 return;
1262
1263         while ((bio = bio_list_pop(&deferred_bios))) {
1264                 r = writeset_test_and_set(&era->md->bitset_info, ws,
1265                                           get_block(era, bio));
1266                 if (r < 0) {
1267                         /*
1268                          * This is bad news, we need to rollback.
1269                          * FIXME: finish.
1270                          */
1271                         failed = true;
1272                 } else if (r == 0)
1273                         commit_needed = true;
1274
1275                 bio_list_add(&marked_bios, bio);
1276         }
1277
1278         if (commit_needed) {
1279                 r = metadata_commit(era->md);
1280                 if (r)
1281                         failed = true;
1282         }
1283
1284         if (failed)
1285                 while ((bio = bio_list_pop(&marked_bios)))
1286                         bio_io_error(bio);
1287         else {
1288                 blk_start_plug(&plug);
1289                 while ((bio = bio_list_pop(&marked_bios))) {
1290                         /*
1291                          * Only update the in-core writeset if the on-disk one
1292                          * was updated too.
1293                          */
1294                         if (commit_needed)
1295                                 set_bit(get_block(era, bio), ws->bits);
1296                         submit_bio_noacct(bio);
1297                 }
1298                 blk_finish_plug(&plug);
1299         }
1300 }
1301
1302 static void process_rpc_calls(struct era *era)
1303 {
1304         int r;
1305         bool need_commit = false;
1306         struct list_head calls;
1307         struct rpc *rpc, *tmp;
1308
1309         INIT_LIST_HEAD(&calls);
1310         spin_lock(&era->rpc_lock);
1311         list_splice_init(&era->rpc_calls, &calls);
1312         spin_unlock(&era->rpc_lock);
1313
1314         list_for_each_entry_safe(rpc, tmp, &calls, list) {
1315                 rpc->result = rpc->fn0 ? rpc->fn0(era->md) : rpc->fn1(era->md, rpc->arg);
1316                 need_commit = true;
1317         }
1318
1319         if (need_commit) {
1320                 r = metadata_commit(era->md);
1321                 if (r)
1322                         list_for_each_entry_safe(rpc, tmp, &calls, list)
1323                                 rpc->result = r;
1324         }
1325
1326         list_for_each_entry_safe(rpc, tmp, &calls, list)
1327                 complete(&rpc->complete);
1328 }
1329
1330 static void kick_off_digest(struct era *era)
1331 {
1332         if (era->md->archived_writesets) {
1333                 era->md->archived_writesets = false;
1334                 metadata_digest_start(era->md, &era->digest);
1335         }
1336 }
1337
1338 static void do_work(struct work_struct *ws)
1339 {
1340         struct era *era = container_of(ws, struct era, worker);
1341
1342         kick_off_digest(era);
1343         process_old_eras(era);
1344         process_deferred_bios(era);
1345         process_rpc_calls(era);
1346 }
1347
1348 static void defer_bio(struct era *era, struct bio *bio)
1349 {
1350         spin_lock(&era->deferred_lock);
1351         bio_list_add(&era->deferred_bios, bio);
1352         spin_unlock(&era->deferred_lock);
1353
1354         wake_worker(era);
1355 }
1356
1357 /*
1358  * Make an rpc call to the worker to change the metadata.
1359  */
1360 static int perform_rpc(struct era *era, struct rpc *rpc)
1361 {
1362         rpc->result = 0;
1363         init_completion(&rpc->complete);
1364
1365         spin_lock(&era->rpc_lock);
1366         list_add(&rpc->list, &era->rpc_calls);
1367         spin_unlock(&era->rpc_lock);
1368
1369         wake_worker(era);
1370         wait_for_completion(&rpc->complete);
1371
1372         return rpc->result;
1373 }
1374
1375 static int in_worker0(struct era *era, int (*fn)(struct era_metadata *))
1376 {
1377         struct rpc rpc;
1378         rpc.fn0 = fn;
1379         rpc.fn1 = NULL;
1380
1381         return perform_rpc(era, &rpc);
1382 }
1383
1384 static int in_worker1(struct era *era,
1385                       int (*fn)(struct era_metadata *, void *), void *arg)
1386 {
1387         struct rpc rpc;
1388         rpc.fn0 = NULL;
1389         rpc.fn1 = fn;
1390         rpc.arg = arg;
1391
1392         return perform_rpc(era, &rpc);
1393 }
1394
1395 static void start_worker(struct era *era)
1396 {
1397         atomic_set(&era->suspended, 0);
1398 }
1399
1400 static void stop_worker(struct era *era)
1401 {
1402         atomic_set(&era->suspended, 1);
1403         drain_workqueue(era->wq);
1404 }
1405
1406 /*----------------------------------------------------------------
1407  * Target methods
1408  *--------------------------------------------------------------*/
1409 static void era_destroy(struct era *era)
1410 {
1411         if (era->md)
1412                 metadata_close(era->md);
1413
1414         if (era->wq)
1415                 destroy_workqueue(era->wq);
1416
1417         if (era->origin_dev)
1418                 dm_put_device(era->ti, era->origin_dev);
1419
1420         if (era->metadata_dev)
1421                 dm_put_device(era->ti, era->metadata_dev);
1422
1423         kfree(era);
1424 }
1425
1426 static dm_block_t calc_nr_blocks(struct era *era)
1427 {
1428         return dm_sector_div_up(era->ti->len, era->sectors_per_block);
1429 }
1430
1431 static bool valid_block_size(dm_block_t block_size)
1432 {
1433         bool greater_than_zero = block_size > 0;
1434         bool multiple_of_min_block_size = (block_size & (MIN_BLOCK_SIZE - 1)) == 0;
1435
1436         return greater_than_zero && multiple_of_min_block_size;
1437 }
1438
1439 /*
1440  * <metadata dev> <data dev> <data block size (sectors)>
1441  */
1442 static int era_ctr(struct dm_target *ti, unsigned argc, char **argv)
1443 {
1444         int r;
1445         char dummy;
1446         struct era *era;
1447         struct era_metadata *md;
1448
1449         if (argc != 3) {
1450                 ti->error = "Invalid argument count";
1451                 return -EINVAL;
1452         }
1453
1454         era = kzalloc(sizeof(*era), GFP_KERNEL);
1455         if (!era) {
1456                 ti->error = "Error allocating era structure";
1457                 return -ENOMEM;
1458         }
1459
1460         era->ti = ti;
1461
1462         r = dm_get_device(ti, argv[0], FMODE_READ | FMODE_WRITE, &era->metadata_dev);
1463         if (r) {
1464                 ti->error = "Error opening metadata device";
1465                 era_destroy(era);
1466                 return -EINVAL;
1467         }
1468
1469         r = dm_get_device(ti, argv[1], FMODE_READ | FMODE_WRITE, &era->origin_dev);
1470         if (r) {
1471                 ti->error = "Error opening data device";
1472                 era_destroy(era);
1473                 return -EINVAL;
1474         }
1475
1476         r = sscanf(argv[2], "%u%c", &era->sectors_per_block, &dummy);
1477         if (r != 1) {
1478                 ti->error = "Error parsing block size";
1479                 era_destroy(era);
1480                 return -EINVAL;
1481         }
1482
1483         r = dm_set_target_max_io_len(ti, era->sectors_per_block);
1484         if (r) {
1485                 ti->error = "could not set max io len";
1486                 era_destroy(era);
1487                 return -EINVAL;
1488         }
1489
1490         if (!valid_block_size(era->sectors_per_block)) {
1491                 ti->error = "Invalid block size";
1492                 era_destroy(era);
1493                 return -EINVAL;
1494         }
1495         if (era->sectors_per_block & (era->sectors_per_block - 1))
1496                 era->sectors_per_block_shift = -1;
1497         else
1498                 era->sectors_per_block_shift = __ffs(era->sectors_per_block);
1499
1500         md = metadata_open(era->metadata_dev->bdev, era->sectors_per_block, true);
1501         if (IS_ERR(md)) {
1502                 ti->error = "Error reading metadata";
1503                 era_destroy(era);
1504                 return PTR_ERR(md);
1505         }
1506         era->md = md;
1507
1508         era->wq = alloc_ordered_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM);
1509         if (!era->wq) {
1510                 ti->error = "could not create workqueue for metadata object";
1511                 era_destroy(era);
1512                 return -ENOMEM;
1513         }
1514         INIT_WORK(&era->worker, do_work);
1515
1516         spin_lock_init(&era->deferred_lock);
1517         bio_list_init(&era->deferred_bios);
1518
1519         spin_lock_init(&era->rpc_lock);
1520         INIT_LIST_HEAD(&era->rpc_calls);
1521
1522         ti->private = era;
1523         ti->num_flush_bios = 1;
1524         ti->flush_supported = true;
1525
1526         ti->num_discard_bios = 1;
1527
1528         return 0;
1529 }
1530
1531 static void era_dtr(struct dm_target *ti)
1532 {
1533         era_destroy(ti->private);
1534 }
1535
1536 static int era_map(struct dm_target *ti, struct bio *bio)
1537 {
1538         struct era *era = ti->private;
1539         dm_block_t block = get_block(era, bio);
1540
1541         /*
1542          * All bios get remapped to the origin device.  We do this now, but
1543          * it may not get issued until later.  Depending on whether the
1544          * block is marked in this era.
1545          */
1546         remap_to_origin(era, bio);
1547
1548         /*
1549          * REQ_PREFLUSH bios carry no data, so we're not interested in them.
1550          */
1551         if (!(bio->bi_opf & REQ_PREFLUSH) &&
1552             (bio_data_dir(bio) == WRITE) &&
1553             !metadata_current_marked(era->md, block)) {
1554                 defer_bio(era, bio);
1555                 return DM_MAPIO_SUBMITTED;
1556         }
1557
1558         return DM_MAPIO_REMAPPED;
1559 }
1560
1561 static void era_postsuspend(struct dm_target *ti)
1562 {
1563         int r;
1564         struct era *era = ti->private;
1565
1566         r = in_worker0(era, metadata_era_archive);
1567         if (r) {
1568                 DMERR("%s: couldn't archive current era", __func__);
1569                 /* FIXME: fail mode */
1570         }
1571
1572         stop_worker(era);
1573
1574         r = metadata_commit(era->md);
1575         if (r) {
1576                 DMERR("%s: metadata_commit failed", __func__);
1577                 /* FIXME: fail mode */
1578         }
1579 }
1580
1581 static int era_preresume(struct dm_target *ti)
1582 {
1583         int r;
1584         struct era *era = ti->private;
1585         dm_block_t new_size = calc_nr_blocks(era);
1586
1587         if (era->nr_blocks != new_size) {
1588                 r = metadata_resize(era->md, &new_size);
1589                 if (r) {
1590                         DMERR("%s: metadata_resize failed", __func__);
1591                         return r;
1592                 }
1593
1594                 r = metadata_commit(era->md);
1595                 if (r) {
1596                         DMERR("%s: metadata_commit failed", __func__);
1597                         return r;
1598                 }
1599
1600                 era->nr_blocks = new_size;
1601         }
1602
1603         start_worker(era);
1604
1605         r = in_worker0(era, metadata_era_rollover);
1606         if (r) {
1607                 DMERR("%s: metadata_era_rollover failed", __func__);
1608                 return r;
1609         }
1610
1611         return 0;
1612 }
1613
1614 /*
1615  * Status format:
1616  *
1617  * <metadata block size> <#used metadata blocks>/<#total metadata blocks>
1618  * <current era> <held metadata root | '-'>
1619  */
1620 static void era_status(struct dm_target *ti, status_type_t type,
1621                        unsigned status_flags, char *result, unsigned maxlen)
1622 {
1623         int r;
1624         struct era *era = ti->private;
1625         ssize_t sz = 0;
1626         struct metadata_stats stats;
1627         char buf[BDEVNAME_SIZE];
1628
1629         switch (type) {
1630         case STATUSTYPE_INFO:
1631                 r = in_worker1(era, metadata_get_stats, &stats);
1632                 if (r)
1633                         goto err;
1634
1635                 DMEMIT("%u %llu/%llu %u",
1636                        (unsigned) (DM_ERA_METADATA_BLOCK_SIZE >> SECTOR_SHIFT),
1637                        (unsigned long long) stats.used,
1638                        (unsigned long long) stats.total,
1639                        (unsigned) stats.era);
1640
1641                 if (stats.snap != SUPERBLOCK_LOCATION)
1642                         DMEMIT(" %llu", stats.snap);
1643                 else
1644                         DMEMIT(" -");
1645                 break;
1646
1647         case STATUSTYPE_TABLE:
1648                 format_dev_t(buf, era->metadata_dev->bdev->bd_dev);
1649                 DMEMIT("%s ", buf);
1650                 format_dev_t(buf, era->origin_dev->bdev->bd_dev);
1651                 DMEMIT("%s %u", buf, era->sectors_per_block);
1652                 break;
1653
1654         case STATUSTYPE_IMA:
1655                 *result = '\0';
1656                 break;
1657         }
1658
1659         return;
1660
1661 err:
1662         DMEMIT("Error");
1663 }
1664
1665 static int era_message(struct dm_target *ti, unsigned argc, char **argv,
1666                        char *result, unsigned maxlen)
1667 {
1668         struct era *era = ti->private;
1669
1670         if (argc != 1) {
1671                 DMERR("incorrect number of message arguments");
1672                 return -EINVAL;
1673         }
1674
1675         if (!strcasecmp(argv[0], "checkpoint"))
1676                 return in_worker0(era, metadata_checkpoint);
1677
1678         if (!strcasecmp(argv[0], "take_metadata_snap"))
1679                 return in_worker0(era, metadata_take_snap);
1680
1681         if (!strcasecmp(argv[0], "drop_metadata_snap"))
1682                 return in_worker0(era, metadata_drop_snap);
1683
1684         DMERR("unsupported message '%s'", argv[0]);
1685         return -EINVAL;
1686 }
1687
1688 static sector_t get_dev_size(struct dm_dev *dev)
1689 {
1690         return i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT;
1691 }
1692
1693 static int era_iterate_devices(struct dm_target *ti,
1694                                iterate_devices_callout_fn fn, void *data)
1695 {
1696         struct era *era = ti->private;
1697         return fn(ti, era->origin_dev, 0, get_dev_size(era->origin_dev), data);
1698 }
1699
1700 static void era_io_hints(struct dm_target *ti, struct queue_limits *limits)
1701 {
1702         struct era *era = ti->private;
1703         uint64_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;
1704
1705         /*
1706          * If the system-determined stacked limits are compatible with the
1707          * era device's blocksize (io_opt is a factor) do not override them.
1708          */
1709         if (io_opt_sectors < era->sectors_per_block ||
1710             do_div(io_opt_sectors, era->sectors_per_block)) {
1711                 blk_limits_io_min(limits, 0);
1712                 blk_limits_io_opt(limits, era->sectors_per_block << SECTOR_SHIFT);
1713         }
1714 }
1715
1716 /*----------------------------------------------------------------*/
1717
1718 static struct target_type era_target = {
1719         .name = "era",
1720         .version = {1, 0, 0},
1721         .module = THIS_MODULE,
1722         .ctr = era_ctr,
1723         .dtr = era_dtr,
1724         .map = era_map,
1725         .postsuspend = era_postsuspend,
1726         .preresume = era_preresume,
1727         .status = era_status,
1728         .message = era_message,
1729         .iterate_devices = era_iterate_devices,
1730         .io_hints = era_io_hints
1731 };
1732
1733 static int __init dm_era_init(void)
1734 {
1735         int r;
1736
1737         r = dm_register_target(&era_target);
1738         if (r) {
1739                 DMERR("era target registration failed: %d", r);
1740                 return r;
1741         }
1742
1743         return 0;
1744 }
1745
1746 static void __exit dm_era_exit(void)
1747 {
1748         dm_unregister_target(&era_target);
1749 }
1750
1751 module_init(dm_era_init);
1752 module_exit(dm_era_exit);
1753
1754 MODULE_DESCRIPTION(DM_NAME " era target");
1755 MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
1756 MODULE_LICENSE("GPL");