drivers/md/persistent-data/dm-space-map-metadata.c

   1 /*
   2  * Copyright (C) 2011 Red Hat, Inc.
   3  *
   4  * This file is released under the GPL.
   5  */
   6
   7 #include "dm-space-map.h"
   8 #include "dm-space-map-common.h"
   9 #include "dm-space-map-metadata.h"
  10
  11 #include <linux/list.h>
  12 #include <linux/slab.h>
  13 #include <linux/device-mapper.h>
  14
  15 #define DM_MSG_PREFIX "space map metadata"
  16
  17 /*----------------------------------------------------------------*/
  18
  19 /*
  20  * An edge triggered threshold.
  21  */
  22 struct threshold {
  23         bool threshold_set;
  24         bool value_set;
  25         dm_block_t threshold;
  26         dm_block_t current_value;
  27         dm_sm_threshold_fn fn;
  28         void *context;
  29 };
  30
  31 static void threshold_init(struct threshold *t)
  32 {
  33         t->threshold_set = false;
  34         t->value_set = false;
  35 }
  36
  37 static void set_threshold(struct threshold *t, dm_block_t value,
  38                           dm_sm_threshold_fn fn, void *context)
  39 {
  40         t->threshold_set = true;
  41         t->threshold = value;
  42         t->fn = fn;
  43         t->context = context;
  44 }
  45
  46 static bool below_threshold(struct threshold *t, dm_block_t value)
  47 {
  48         return t->threshold_set && value <= t->threshold;
  49 }
  50
  51 static bool threshold_already_triggered(struct threshold *t)
  52 {
  53         return t->value_set && below_threshold(t, t->current_value);
  54 }
  55
  56 static void check_threshold(struct threshold *t, dm_block_t value)
  57 {
  58         if (below_threshold(t, value) &&
  59             !threshold_already_triggered(t))
  60                 t->fn(t->context);
  61
  62         t->value_set = true;
  63         t->current_value = value;
  64 }
  65
  66 /*----------------------------------------------------------------*/
  67
  68 /*
  69  * Space map interface.
  70  *
  71  * The low level disk format is written using the standard btree and
  72  * transaction manager.  This means that performing disk operations may
  73  * cause us to recurse into the space map in order to allocate new blocks.
  74  * For this reason we have a pool of pre-allocated blocks large enough to
  75  * service any metadata_ll_disk operation.
  76  */
  77
  78 /*
  79  * FIXME: we should calculate this based on the size of the device.
  80  * Only the metadata space map needs this functionality.
  81  */
  82 #define MAX_RECURSIVE_ALLOCATIONS 1024
  83
  84 enum block_op_type {
  85         BOP_INC,
  86         BOP_DEC
  87 };
  88
  89 struct block_op {
  90         enum block_op_type type;
  91         dm_block_t block;
  92 };
  93
  94 struct bop_ring_buffer {
  95         unsigned begin;
  96         unsigned end;
  97         struct block_op bops[MAX_RECURSIVE_ALLOCATIONS + 1];
  98 };
  99
 100 static void brb_init(struct bop_ring_buffer *brb)
 101 {
 102         brb->begin = 0;
 103         brb->end = 0;
 104 }
 105
 106 static bool brb_empty(struct bop_ring_buffer *brb)
 107 {
 108         return brb->begin == brb->end;
 109 }
 110
 111 static unsigned brb_next(struct bop_ring_buffer *brb, unsigned old)
 112 {
 113         unsigned r = old + 1;
 114         return (r >= (sizeof(brb->bops) / sizeof(*brb->bops))) ? 0 : r;
 115 }
 116
 117 static int brb_push(struct bop_ring_buffer *brb,
 118                     enum block_op_type type, dm_block_t b)
 119 {
 120         struct block_op *bop;
 121         unsigned next = brb_next(brb, brb->end);
 122
 123         /*
 124          * We don't allow the last bop to be filled, this way we can
 125          * differentiate between full and empty.
 126          */
 127         if (next == brb->begin)
 128                 return -ENOMEM;
 129
 130         bop = brb->bops + brb->end;
 131         bop->type = type;
 132         bop->block = b;
 133
 134         brb->end = next;
 135
 136         return 0;
 137 }
 138
 139 static int brb_peek(struct bop_ring_buffer *brb, struct block_op *result)
 140 {
 141         struct block_op *bop;
 142
 143         if (brb_empty(brb))
 144                 return -ENODATA;
 145
 146         bop = brb->bops + brb->begin;
 147         result->type = bop->type;
 148         result->block = bop->block;
 149
 150         return 0;
 151 }
 152
 153 static int brb_pop(struct bop_ring_buffer *brb)
 154 {
 155         if (brb_empty(brb))
 156                 return -ENODATA;
 157
 158         brb->begin = brb_next(brb, brb->begin);
 159
 160         return 0;
 161 }
 162
 163 /*----------------------------------------------------------------*/
 164
 165 struct sm_metadata {
 166         struct dm_space_map sm;
 167
 168         struct ll_disk ll;
 169         struct ll_disk old_ll;
 170
 171         dm_block_t begin;
 172
 173         unsigned recursion_count;
 174         unsigned allocated_this_transaction;
 175         struct bop_ring_buffer uncommitted;
 176
 177         struct threshold threshold;
 178 };
 179
 180 static int add_bop(struct sm_metadata *smm, enum block_op_type type, dm_block_t b)
 181 {
 182         int r = brb_push(&smm->uncommitted, type, b);
 183
 184         if (r) {
 185                 DMERR("too many recursive allocations");
 186                 return -ENOMEM;
 187         }
 188
 189         return 0;
 190 }
 191
 192 static int commit_bop(struct sm_metadata *smm, struct block_op *op)
 193 {
 194         int r = 0;
 195         enum allocation_event ev;
 196
 197         switch (op->type) {
 198         case BOP_INC:
 199                 r = sm_ll_inc(&smm->ll, op->block, &ev);
 200                 break;
 201
 202         case BOP_DEC:
 203                 r = sm_ll_dec(&smm->ll, op->block, &ev);
 204                 break;
 205         }
 206
 207         return r;
 208 }
 209
 210 static void in(struct sm_metadata *smm)
 211 {
 212         smm->recursion_count++;
 213 }
 214
 215 static int apply_bops(struct sm_metadata *smm)
 216 {
 217         int r = 0;
 218
 219         while (!brb_empty(&smm->uncommitted)) {
 220                 struct block_op bop;
 221
 222                 r = brb_peek(&smm->uncommitted, &bop);
 223                 if (r) {
 224                         DMERR("bug in bop ring buffer");
 225                         break;
 226                 }
 227
 228                 r = commit_bop(smm, &bop);
 229                 if (r)
 230                         break;
 231
 232                 brb_pop(&smm->uncommitted);
 233         }
 234
 235         return r;
 236 }
 237
 238 static int out(struct sm_metadata *smm)
 239 {
 240         int r = 0;
 241
 242         /*
 243          * If we're not recursing then very bad things are happening.
 244          */
 245         if (!smm->recursion_count) {
 246                 DMERR("lost track of recursion depth");
 247                 return -ENOMEM;
 248         }
 249
 250         if (smm->recursion_count == 1)
 251                 apply_bops(smm);
 252
 253         smm->recursion_count--;
 254
 255         return r;
 256 }
 257
 258 /*
 259  * When using the out() function above, we often want to combine an error
 260  * code for the operation run in the recursive context with that from
 261  * out().
 262  */
 263 static int combine_errors(int r1, int r2)
 264 {
 265         return r1 ? r1 : r2;
 266 }
 267
 268 static int recursing(struct sm_metadata *smm)
 269 {
 270         return smm->recursion_count;
 271 }
 272
 273 static void sm_metadata_destroy(struct dm_space_map *sm)
 274 {
 275         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 276
 277         kfree(smm);
 278 }
 279
 280 static int sm_metadata_get_nr_blocks(struct dm_space_map *sm, dm_block_t *count)
 281 {
 282         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 283
 284         *count = smm->ll.nr_blocks;
 285
 286         return 0;
 287 }
 288
 289 static int sm_metadata_get_nr_free(struct dm_space_map *sm, dm_block_t *count)
 290 {
 291         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 292
 293         *count = smm->old_ll.nr_blocks - smm->old_ll.nr_allocated -
 294                  smm->allocated_this_transaction;
 295
 296         return 0;
 297 }
 298
 299 static int sm_metadata_get_count(struct dm_space_map *sm, dm_block_t b,
 300                                  uint32_t *result)
 301 {
 302         int r;
 303         unsigned i;
 304         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 305         unsigned adjustment = 0;
 306
 307         /*
 308          * We may have some uncommitted adjustments to add.  This list
 309          * should always be really short.
 310          */
 311         for (i = smm->uncommitted.begin;
 312              i != smm->uncommitted.end;
 313              i = brb_next(&smm->uncommitted, i)) {
 314                 struct block_op *op = smm->uncommitted.bops + i;
 315
 316                 if (op->block != b)
 317                         continue;
 318
 319                 switch (op->type) {
 320                 case BOP_INC:
 321                         adjustment++;
 322                         break;
 323
 324                 case BOP_DEC:
 325                         adjustment--;
 326                         break;
 327                 }
 328         }
 329
 330         r = sm_ll_lookup(&smm->ll, b, result);
 331         if (r)
 332                 return r;
 333
 334         *result += adjustment;
 335
 336         return 0;
 337 }
 338
 339 static int sm_metadata_count_is_more_than_one(struct dm_space_map *sm,
 340                                               dm_block_t b, int *result)
 341 {
 342         int r, adjustment = 0;
 343         unsigned i;
 344         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 345         uint32_t rc;
 346
 347         /*
 348          * We may have some uncommitted adjustments to add.  This list
 349          * should always be really short.
 350          */
 351         for (i = smm->uncommitted.begin;
 352              i != smm->uncommitted.end;
 353              i = brb_next(&smm->uncommitted, i)) {
 354
 355                 struct block_op *op = smm->uncommitted.bops + i;
 356
 357                 if (op->block != b)
 358                         continue;
 359
 360                 switch (op->type) {
 361                 case BOP_INC:
 362                         adjustment++;
 363                         break;
 364
 365                 case BOP_DEC:
 366                         adjustment--;
 367                         break;
 368                 }
 369         }
 370
 371         if (adjustment > 1) {
 372                 *result = 1;
 373                 return 0;
 374         }
 375
 376         r = sm_ll_lookup_bitmap(&smm->ll, b, &rc);
 377         if (r)
 378                 return r;
 379
 380         if (rc == 3)
 381                 /*
 382                  * We err on the side of caution, and always return true.
 383                  */
 384                 *result = 1;
 385         else
 386                 *result = rc + adjustment > 1;
 387
 388         return 0;
 389 }
 390
 391 static int sm_metadata_set_count(struct dm_space_map *sm, dm_block_t b,
 392                                  uint32_t count)
 393 {
 394         int r, r2;
 395         enum allocation_event ev;
 396         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 397
 398         if (smm->recursion_count) {
 399                 DMERR("cannot recurse set_count()");
 400                 return -EINVAL;
 401         }
 402
 403         in(smm);
 404         r = sm_ll_insert(&smm->ll, b, count, &ev);
 405         r2 = out(smm);
 406
 407         return combine_errors(r, r2);
 408 }
 409
 410 static int sm_metadata_inc_block(struct dm_space_map *sm, dm_block_t b)
 411 {
 412         int r, r2 = 0;
 413         enum allocation_event ev;
 414         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 415
 416         if (recursing(smm))
 417                 r = add_bop(smm, BOP_INC, b);
 418         else {
 419                 in(smm);
 420                 r = sm_ll_inc(&smm->ll, b, &ev);
 421                 r2 = out(smm);
 422         }
 423
 424         return combine_errors(r, r2);
 425 }
 426
 427 static int sm_metadata_dec_block(struct dm_space_map *sm, dm_block_t b)
 428 {
 429         int r, r2 = 0;
 430         enum allocation_event ev;
 431         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 432
 433         if (recursing(smm))
 434                 r = add_bop(smm, BOP_DEC, b);
 435         else {
 436                 in(smm);
 437                 r = sm_ll_dec(&smm->ll, b, &ev);
 438                 r2 = out(smm);
 439         }
 440
 441         return combine_errors(r, r2);
 442 }
 443
 444 static int sm_metadata_new_block_(struct dm_space_map *sm, dm_block_t *b)
 445 {
 446         int r, r2 = 0;
 447         enum allocation_event ev;
 448         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 449
 450         r = sm_ll_find_free_block(&smm->old_ll, smm->begin, smm->old_ll.nr_blocks, b);
 451         if (r)
 452                 return r;
 453
 454         smm->begin = *b + 1;
 455
 456         if (recursing(smm))
 457                 r = add_bop(smm, BOP_INC, *b);
 458         else {
 459                 in(smm);
 460                 r = sm_ll_inc(&smm->ll, *b, &ev);
 461                 r2 = out(smm);
 462         }
 463
 464         if (!r)
 465                 smm->allocated_this_transaction++;
 466
 467         return combine_errors(r, r2);
 468 }
 469
 470 static int sm_metadata_new_block(struct dm_space_map *sm, dm_block_t *b)
 471 {
 472         dm_block_t count;
 473         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 474
 475         int r = sm_metadata_new_block_(sm, b);
 476         if (r) {
 477                 DMERR_LIMIT("unable to allocate new metadata block");
 478                 return r;
 479         }
 480
 481         r = sm_metadata_get_nr_free(sm, &count);
 482         if (r) {
 483                 DMERR_LIMIT("couldn't get free block count");
 484                 return r;
 485         }
 486
 487         check_threshold(&smm->threshold, count);
 488
 489         return r;
 490 }
 491
 492 static int sm_metadata_commit(struct dm_space_map *sm)
 493 {
 494         int r;
 495         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 496
 497         r = sm_ll_commit(&smm->ll);
 498         if (r)
 499                 return r;
 500
 501         memcpy(&smm->old_ll, &smm->ll, sizeof(smm->old_ll));
 502         smm->begin = 0;
 503         smm->allocated_this_transaction = 0;
 504
 505         return 0;
 506 }
 507
 508 static int sm_metadata_register_threshold_callback(struct dm_space_map *sm,
 509                                                    dm_block_t threshold,
 510                                                    dm_sm_threshold_fn fn,
 511                                                    void *context)
 512 {
 513         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 514
 515         set_threshold(&smm->threshold, threshold, fn, context);
 516
 517         return 0;
 518 }
 519
 520 static int sm_metadata_root_size(struct dm_space_map *sm, size_t *result)
 521 {
 522         *result = sizeof(struct disk_sm_root);
 523
 524         return 0;
 525 }
 526
 527 static int sm_metadata_copy_root(struct dm_space_map *sm, void *where_le, size_t max)
 528 {
 529         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 530         struct disk_sm_root root_le;
 531
 532         root_le.nr_blocks = cpu_to_le64(smm->ll.nr_blocks);
 533         root_le.nr_allocated = cpu_to_le64(smm->ll.nr_allocated);
 534         root_le.bitmap_root = cpu_to_le64(smm->ll.bitmap_root);
 535         root_le.ref_count_root = cpu_to_le64(smm->ll.ref_count_root);
 536
 537         if (max < sizeof(root_le))
 538                 return -ENOSPC;
 539
 540         memcpy(where_le, &root_le, sizeof(root_le));
 541
 542         return 0;
 543 }
 544
 545 static int sm_metadata_extend(struct dm_space_map *sm, dm_block_t extra_blocks);
 546
 547 static struct dm_space_map ops = {
 548         .destroy = sm_metadata_destroy,
 549         .extend = sm_metadata_extend,
 550         .get_nr_blocks = sm_metadata_get_nr_blocks,
 551         .get_nr_free = sm_metadata_get_nr_free,
 552         .get_count = sm_metadata_get_count,
 553         .count_is_more_than_one = sm_metadata_count_is_more_than_one,
 554         .set_count = sm_metadata_set_count,
 555         .inc_block = sm_metadata_inc_block,
 556         .dec_block = sm_metadata_dec_block,
 557         .new_block = sm_metadata_new_block,
 558         .commit = sm_metadata_commit,
 559         .root_size = sm_metadata_root_size,
 560         .copy_root = sm_metadata_copy_root,
 561         .register_threshold_callback = sm_metadata_register_threshold_callback
 562 };
 563
 564 /*----------------------------------------------------------------*/
 565
 566 /*
 567  * When a new space map is created that manages its own space.  We use
 568  * this tiny bootstrap allocator.
 569  */
 570 static void sm_bootstrap_destroy(struct dm_space_map *sm)
 571 {
 572 }
 573
 574 static int sm_bootstrap_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
 575 {
 576         DMERR("bootstrap doesn't support extend");
 577
 578         return -EINVAL;
 579 }
 580
 581 static int sm_bootstrap_get_nr_blocks(struct dm_space_map *sm, dm_block_t *count)
 582 {
 583         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 584
 585         *count = smm->ll.nr_blocks;
 586
 587         return 0;
 588 }
 589
 590 static int sm_bootstrap_get_nr_free(struct dm_space_map *sm, dm_block_t *count)
 591 {
 592         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 593
 594         *count = smm->ll.nr_blocks - smm->begin;
 595
 596         return 0;
 597 }
 598
 599 static int sm_bootstrap_get_count(struct dm_space_map *sm, dm_block_t b,
 600                                   uint32_t *result)
 601 {
 602         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 603
 604         *result = (b < smm->begin) ? 1 : 0;
 605
 606         return 0;
 607 }
 608
 609 static int sm_bootstrap_count_is_more_than_one(struct dm_space_map *sm,
 610                                                dm_block_t b, int *result)
 611 {
 612         *result = 0;
 613
 614         return 0;
 615 }
 616
 617 static int sm_bootstrap_set_count(struct dm_space_map *sm, dm_block_t b,
 618                                   uint32_t count)
 619 {
 620         DMERR("bootstrap doesn't support set_count");
 621
 622         return -EINVAL;
 623 }
 624
 625 static int sm_bootstrap_new_block(struct dm_space_map *sm, dm_block_t *b)
 626 {
 627         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 628
 629         /*
 630          * We know the entire device is unused.
 631          */
 632         if (smm->begin == smm->ll.nr_blocks)
 633                 return -ENOSPC;
 634
 635         *b = smm->begin++;
 636
 637         return 0;
 638 }
 639
 640 static int sm_bootstrap_inc_block(struct dm_space_map *sm, dm_block_t b)
 641 {
 642         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 643
 644         return add_bop(smm, BOP_INC, b);
 645 }
 646
 647 static int sm_bootstrap_dec_block(struct dm_space_map *sm, dm_block_t b)
 648 {
 649         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 650
 651         return add_bop(smm, BOP_DEC, b);
 652 }
 653
 654 static int sm_bootstrap_commit(struct dm_space_map *sm)
 655 {
 656         return 0;
 657 }
 658
 659 static int sm_bootstrap_root_size(struct dm_space_map *sm, size_t *result)
 660 {
 661         DMERR("bootstrap doesn't support root_size");
 662
 663         return -EINVAL;
 664 }
 665
 666 static int sm_bootstrap_copy_root(struct dm_space_map *sm, void *where,
 667                                   size_t max)
 668 {
 669         DMERR("bootstrap doesn't support copy_root");
 670
 671         return -EINVAL;
 672 }
 673
 674 static struct dm_space_map bootstrap_ops = {
 675         .destroy = sm_bootstrap_destroy,
 676         .extend = sm_bootstrap_extend,
 677         .get_nr_blocks = sm_bootstrap_get_nr_blocks,
 678         .get_nr_free = sm_bootstrap_get_nr_free,
 679         .get_count = sm_bootstrap_get_count,
 680         .count_is_more_than_one = sm_bootstrap_count_is_more_than_one,
 681         .set_count = sm_bootstrap_set_count,
 682         .inc_block = sm_bootstrap_inc_block,
 683         .dec_block = sm_bootstrap_dec_block,
 684         .new_block = sm_bootstrap_new_block,
 685         .commit = sm_bootstrap_commit,
 686         .root_size = sm_bootstrap_root_size,
 687         .copy_root = sm_bootstrap_copy_root,
 688         .register_threshold_callback = NULL
 689 };
 690
 691 /*----------------------------------------------------------------*/
 692
 693 static int sm_metadata_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
 694 {
 695         int r, i;
 696         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 697         dm_block_t old_len = smm->ll.nr_blocks;
 698
 699         /*
 700          * Flick into a mode where all blocks get allocated in the new area.
 701          */
 702         smm->begin = old_len;
 703         memcpy(sm, &bootstrap_ops, sizeof(*sm));
 704
 705         /*
 706          * Extend.
 707          */
 708         r = sm_ll_extend(&smm->ll, extra_blocks);
 709         if (r)
 710                 goto out;
 711
 712         /*
 713          * We repeatedly increment then commit until the commit doesn't
 714          * allocate any new blocks.
 715          */
 716         do {
 717                 for (i = old_len; !r && i < smm->begin; i++)
 718                         r = add_bop(smm, BOP_INC, i);
 719
 720                 if (r)
 721                         goto out;
 722
 723                 old_len = smm->begin;
 724
 725                 r = apply_bops(smm);
 726                 if (r) {
 727                         DMERR("%s: apply_bops failed", __func__);
 728                         goto out;
 729                 }
 730
 731                 r = sm_ll_commit(&smm->ll);
 732                 if (r)
 733                         goto out;
 734
 735         } while (old_len != smm->begin);
 736
 737 out:
 738         /*
 739          * Switch back to normal behaviour.
 740          */
 741         memcpy(sm, &ops, sizeof(*sm));
 742         return r;
 743 }
 744
 745 /*----------------------------------------------------------------*/
 746
 747 struct dm_space_map *dm_sm_metadata_init(void)
 748 {
 749         struct sm_metadata *smm;
 750
 751         smm = kmalloc(sizeof(*smm), GFP_KERNEL);
 752         if (!smm)
 753                 return ERR_PTR(-ENOMEM);
 754
 755         memcpy(&smm->sm, &ops, sizeof(smm->sm));
 756
 757         return &smm->sm;
 758 }
 759
 760 int dm_sm_metadata_create(struct dm_space_map *sm,
 761                           struct dm_transaction_manager *tm,
 762                           dm_block_t nr_blocks,
 763                           dm_block_t superblock)
 764 {
 765         int r;
 766         dm_block_t i;
 767         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 768
 769         smm->begin = superblock + 1;
 770         smm->recursion_count = 0;
 771         smm->allocated_this_transaction = 0;
 772         brb_init(&smm->uncommitted);
 773         threshold_init(&smm->threshold);
 774
 775         memcpy(&smm->sm, &bootstrap_ops, sizeof(smm->sm));
 776
 777         r = sm_ll_new_metadata(&smm->ll, tm);
 778         if (r)
 779                 return r;
 780
 781         if (nr_blocks > DM_SM_METADATA_MAX_BLOCKS)
 782                 nr_blocks = DM_SM_METADATA_MAX_BLOCKS;
 783         r = sm_ll_extend(&smm->ll, nr_blocks);
 784         if (r)
 785                 return r;
 786
 787         memcpy(&smm->sm, &ops, sizeof(smm->sm));
 788
 789         /*
 790          * Now we need to update the newly created data structures with the
 791          * allocated blocks that they were built from.
 792          */
 793         for (i = superblock; !r && i < smm->begin; i++)
 794                 r = add_bop(smm, BOP_INC, i);
 795
 796         if (r)
 797                 return r;
 798
 799         r = apply_bops(smm);
 800         if (r) {
 801                 DMERR("%s: apply_bops failed", __func__);
 802                 return r;
 803         }
 804
 805         return sm_metadata_commit(sm);
 806 }
 807
 808 int dm_sm_metadata_open(struct dm_space_map *sm,
 809                         struct dm_transaction_manager *tm,
 810                         void *root_le, size_t len)
 811 {
 812         int r;
 813         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 814
 815         r = sm_ll_open_metadata(&smm->ll, tm, root_le, len);
 816         if (r)
 817                 return r;
 818
 819         smm->begin = 0;
 820         smm->recursion_count = 0;
 821         smm->allocated_this_transaction = 0;
 822         brb_init(&smm->uncommitted);
 823         threshold_init(&smm->threshold);
 824
 825         memcpy(&smm->old_ll, &smm->ll, sizeof(smm->old_ll));
 826         return 0;
 827 }