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 sm_metadata {
  95         struct dm_space_map sm;
  96
  97         struct ll_disk ll;
  98         struct ll_disk old_ll;
  99
 100         dm_block_t begin;
 101
 102         unsigned recursion_count;
 103         unsigned allocated_this_transaction;
 104         unsigned nr_uncommitted;
 105         struct block_op uncommitted[MAX_RECURSIVE_ALLOCATIONS];
 106
 107         struct threshold threshold;
 108 };
 109
 110 static int add_bop(struct sm_metadata *smm, enum block_op_type type, dm_block_t b)
 111 {
 112         struct block_op *op;
 113
 114         if (smm->nr_uncommitted == MAX_RECURSIVE_ALLOCATIONS) {
 115                 DMERR("too many recursive allocations");
 116                 return -ENOMEM;
 117         }
 118
 119         op = smm->uncommitted + smm->nr_uncommitted++;
 120         op->type = type;
 121         op->block = b;
 122
 123         return 0;
 124 }
 125
 126 static int commit_bop(struct sm_metadata *smm, struct block_op *op)
 127 {
 128         int r = 0;
 129         enum allocation_event ev;
 130
 131         switch (op->type) {
 132         case BOP_INC:
 133                 r = sm_ll_inc(&smm->ll, op->block, &ev);
 134                 break;
 135
 136         case BOP_DEC:
 137                 r = sm_ll_dec(&smm->ll, op->block, &ev);
 138                 break;
 139         }
 140
 141         return r;
 142 }
 143
 144 static void in(struct sm_metadata *smm)
 145 {
 146         smm->recursion_count++;
 147 }
 148
 149 static int out(struct sm_metadata *smm)
 150 {
 151         int r = 0;
 152
 153         /*
 154          * If we're not recursing then very bad things are happening.
 155          */
 156         if (!smm->recursion_count) {
 157                 DMERR("lost track of recursion depth");
 158                 return -ENOMEM;
 159         }
 160
 161         if (smm->recursion_count == 1 && smm->nr_uncommitted) {
 162                 while (smm->nr_uncommitted && !r) {
 163                         smm->nr_uncommitted--;
 164                         r = commit_bop(smm, smm->uncommitted +
 165                                        smm->nr_uncommitted);
 166                         if (r)
 167                                 break;
 168                 }
 169         }
 170
 171         smm->recursion_count--;
 172
 173         return r;
 174 }
 175
 176 /*
 177  * When using the out() function above, we often want to combine an error
 178  * code for the operation run in the recursive context with that from
 179  * out().
 180  */
 181 static int combine_errors(int r1, int r2)
 182 {
 183         return r1 ? r1 : r2;
 184 }
 185
 186 static int recursing(struct sm_metadata *smm)
 187 {
 188         return smm->recursion_count;
 189 }
 190
 191 static void sm_metadata_destroy(struct dm_space_map *sm)
 192 {
 193         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 194
 195         kfree(smm);
 196 }
 197
 198 static int sm_metadata_get_nr_blocks(struct dm_space_map *sm, dm_block_t *count)
 199 {
 200         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 201
 202         *count = smm->ll.nr_blocks;
 203
 204         return 0;
 205 }
 206
 207 static int sm_metadata_get_nr_free(struct dm_space_map *sm, dm_block_t *count)
 208 {
 209         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 210
 211         *count = smm->old_ll.nr_blocks - smm->old_ll.nr_allocated -
 212                  smm->allocated_this_transaction;
 213
 214         return 0;
 215 }
 216
 217 static int sm_metadata_get_count(struct dm_space_map *sm, dm_block_t b,
 218                                  uint32_t *result)
 219 {
 220         int r, i;
 221         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 222         unsigned adjustment = 0;
 223
 224         /*
 225          * We may have some uncommitted adjustments to add.  This list
 226          * should always be really short.
 227          */
 228         for (i = 0; i < smm->nr_uncommitted; i++) {
 229                 struct block_op *op = smm->uncommitted + i;
 230
 231                 if (op->block != b)
 232                         continue;
 233
 234                 switch (op->type) {
 235                 case BOP_INC:
 236                         adjustment++;
 237                         break;
 238
 239                 case BOP_DEC:
 240                         adjustment--;
 241                         break;
 242                 }
 243         }
 244
 245         r = sm_ll_lookup(&smm->ll, b, result);
 246         if (r)
 247                 return r;
 248
 249         *result += adjustment;
 250
 251         return 0;
 252 }
 253
 254 static int sm_metadata_count_is_more_than_one(struct dm_space_map *sm,
 255                                               dm_block_t b, int *result)
 256 {
 257         int r, i, adjustment = 0;
 258         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 259         uint32_t rc;
 260
 261         /*
 262          * We may have some uncommitted adjustments to add.  This list
 263          * should always be really short.
 264          */
 265         for (i = 0; i < smm->nr_uncommitted; i++) {
 266                 struct block_op *op = smm->uncommitted + i;
 267
 268                 if (op->block != b)
 269                         continue;
 270
 271                 switch (op->type) {
 272                 case BOP_INC:
 273                         adjustment++;
 274                         break;
 275
 276                 case BOP_DEC:
 277                         adjustment--;
 278                         break;
 279                 }
 280         }
 281
 282         if (adjustment > 1) {
 283                 *result = 1;
 284                 return 0;
 285         }
 286
 287         r = sm_ll_lookup_bitmap(&smm->ll, b, &rc);
 288         if (r)
 289                 return r;
 290
 291         if (rc == 3)
 292                 /*
 293                  * We err on the side of caution, and always return true.
 294                  */
 295                 *result = 1;
 296         else
 297                 *result = rc + adjustment > 1;
 298
 299         return 0;
 300 }
 301
 302 static int sm_metadata_set_count(struct dm_space_map *sm, dm_block_t b,
 303                                  uint32_t count)
 304 {
 305         int r, r2;
 306         enum allocation_event ev;
 307         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 308
 309         if (smm->recursion_count) {
 310                 DMERR("cannot recurse set_count()");
 311                 return -EINVAL;
 312         }
 313
 314         in(smm);
 315         r = sm_ll_insert(&smm->ll, b, count, &ev);
 316         r2 = out(smm);
 317
 318         return combine_errors(r, r2);
 319 }
 320
 321 static int sm_metadata_inc_block(struct dm_space_map *sm, dm_block_t b)
 322 {
 323         int r, r2 = 0;
 324         enum allocation_event ev;
 325         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 326
 327         if (recursing(smm))
 328                 r = add_bop(smm, BOP_INC, b);
 329         else {
 330                 in(smm);
 331                 r = sm_ll_inc(&smm->ll, b, &ev);
 332                 r2 = out(smm);
 333         }
 334
 335         return combine_errors(r, r2);
 336 }
 337
 338 static int sm_metadata_dec_block(struct dm_space_map *sm, dm_block_t b)
 339 {
 340         int r, r2 = 0;
 341         enum allocation_event ev;
 342         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 343
 344         if (recursing(smm))
 345                 r = add_bop(smm, BOP_DEC, b);
 346         else {
 347                 in(smm);
 348                 r = sm_ll_dec(&smm->ll, b, &ev);
 349                 r2 = out(smm);
 350         }
 351
 352         return combine_errors(r, r2);
 353 }
 354
 355 static int sm_metadata_new_block_(struct dm_space_map *sm, dm_block_t *b)
 356 {
 357         int r, r2 = 0;
 358         enum allocation_event ev;
 359         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 360
 361         r = sm_ll_find_free_block(&smm->old_ll, smm->begin, smm->old_ll.nr_blocks, b);
 362         if (r)
 363                 return r;
 364
 365         smm->begin = *b + 1;
 366
 367         if (recursing(smm))
 368                 r = add_bop(smm, BOP_INC, *b);
 369         else {
 370                 in(smm);
 371                 r = sm_ll_inc(&smm->ll, *b, &ev);
 372                 r2 = out(smm);
 373         }
 374
 375         if (!r)
 376                 smm->allocated_this_transaction++;
 377
 378         return combine_errors(r, r2);
 379 }
 380
 381 static int sm_metadata_new_block(struct dm_space_map *sm, dm_block_t *b)
 382 {
 383         dm_block_t count;
 384         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 385
 386         int r = sm_metadata_new_block_(sm, b);
 387         if (r) {
 388                 DMERR_LIMIT("unable to allocate new metadata block");
 389                 return r;
 390         }
 391
 392         r = sm_metadata_get_nr_free(sm, &count);
 393         if (r) {
 394                 DMERR_LIMIT("couldn't get free block count");
 395                 return r;
 396         }
 397
 398         check_threshold(&smm->threshold, count);
 399
 400         return r;
 401 }
 402
 403 static int sm_metadata_commit(struct dm_space_map *sm)
 404 {
 405         int r;
 406         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 407
 408         r = sm_ll_commit(&smm->ll);
 409         if (r)
 410                 return r;
 411
 412         memcpy(&smm->old_ll, &smm->ll, sizeof(smm->old_ll));
 413         smm->begin = 0;
 414         smm->allocated_this_transaction = 0;
 415
 416         return 0;
 417 }
 418
 419 static int sm_metadata_register_threshold_callback(struct dm_space_map *sm,
 420                                                    dm_block_t threshold,
 421                                                    dm_sm_threshold_fn fn,
 422                                                    void *context)
 423 {
 424         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 425
 426         set_threshold(&smm->threshold, threshold, fn, context);
 427
 428         return 0;
 429 }
 430
 431 static int sm_metadata_root_size(struct dm_space_map *sm, size_t *result)
 432 {
 433         *result = sizeof(struct disk_sm_root);
 434
 435         return 0;
 436 }
 437
 438 static int sm_metadata_copy_root(struct dm_space_map *sm, void *where_le, size_t max)
 439 {
 440         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 441         struct disk_sm_root root_le;
 442
 443         root_le.nr_blocks = cpu_to_le64(smm->ll.nr_blocks);
 444         root_le.nr_allocated = cpu_to_le64(smm->ll.nr_allocated);
 445         root_le.bitmap_root = cpu_to_le64(smm->ll.bitmap_root);
 446         root_le.ref_count_root = cpu_to_le64(smm->ll.ref_count_root);
 447
 448         if (max < sizeof(root_le))
 449                 return -ENOSPC;
 450
 451         memcpy(where_le, &root_le, sizeof(root_le));
 452
 453         return 0;
 454 }
 455
 456 static int sm_metadata_extend(struct dm_space_map *sm, dm_block_t extra_blocks);
 457
 458 static struct dm_space_map ops = {
 459         .destroy = sm_metadata_destroy,
 460         .extend = sm_metadata_extend,
 461         .get_nr_blocks = sm_metadata_get_nr_blocks,
 462         .get_nr_free = sm_metadata_get_nr_free,
 463         .get_count = sm_metadata_get_count,
 464         .count_is_more_than_one = sm_metadata_count_is_more_than_one,
 465         .set_count = sm_metadata_set_count,
 466         .inc_block = sm_metadata_inc_block,
 467         .dec_block = sm_metadata_dec_block,
 468         .new_block = sm_metadata_new_block,
 469         .commit = sm_metadata_commit,
 470         .root_size = sm_metadata_root_size,
 471         .copy_root = sm_metadata_copy_root,
 472         .register_threshold_callback = sm_metadata_register_threshold_callback
 473 };
 474
 475 /*----------------------------------------------------------------*/
 476
 477 /*
 478  * When a new space map is created that manages its own space.  We use
 479  * this tiny bootstrap allocator.
 480  */
 481 static void sm_bootstrap_destroy(struct dm_space_map *sm)
 482 {
 483 }
 484
 485 static int sm_bootstrap_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
 486 {
 487         DMERR("bootstrap doesn't support extend");
 488
 489         return -EINVAL;
 490 }
 491
 492 static int sm_bootstrap_get_nr_blocks(struct dm_space_map *sm, dm_block_t *count)
 493 {
 494         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 495
 496         return smm->ll.nr_blocks;
 497 }
 498
 499 static int sm_bootstrap_get_nr_free(struct dm_space_map *sm, dm_block_t *count)
 500 {
 501         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 502
 503         *count = smm->ll.nr_blocks - smm->begin;
 504
 505         return 0;
 506 }
 507
 508 static int sm_bootstrap_get_count(struct dm_space_map *sm, dm_block_t b,
 509                                   uint32_t *result)
 510 {
 511         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 512
 513         return b < smm->begin ? 1 : 0;
 514 }
 515
 516 static int sm_bootstrap_count_is_more_than_one(struct dm_space_map *sm,
 517                                                dm_block_t b, int *result)
 518 {
 519         *result = 0;
 520
 521         return 0;
 522 }
 523
 524 static int sm_bootstrap_set_count(struct dm_space_map *sm, dm_block_t b,
 525                                   uint32_t count)
 526 {
 527         DMERR("bootstrap doesn't support set_count");
 528
 529         return -EINVAL;
 530 }
 531
 532 static int sm_bootstrap_new_block(struct dm_space_map *sm, dm_block_t *b)
 533 {
 534         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 535
 536         /*
 537          * We know the entire device is unused.
 538          */
 539         if (smm->begin == smm->ll.nr_blocks)
 540                 return -ENOSPC;
 541
 542         *b = smm->begin++;
 543
 544         return 0;
 545 }
 546
 547 static int sm_bootstrap_inc_block(struct dm_space_map *sm, dm_block_t b)
 548 {
 549         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 550
 551         return add_bop(smm, BOP_INC, b);
 552 }
 553
 554 static int sm_bootstrap_dec_block(struct dm_space_map *sm, dm_block_t b)
 555 {
 556         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 557
 558         return add_bop(smm, BOP_DEC, b);
 559 }
 560
 561 static int sm_bootstrap_commit(struct dm_space_map *sm)
 562 {
 563         return 0;
 564 }
 565
 566 static int sm_bootstrap_root_size(struct dm_space_map *sm, size_t *result)
 567 {
 568         DMERR("bootstrap doesn't support root_size");
 569
 570         return -EINVAL;
 571 }
 572
 573 static int sm_bootstrap_copy_root(struct dm_space_map *sm, void *where,
 574                                   size_t max)
 575 {
 576         DMERR("bootstrap doesn't support copy_root");
 577
 578         return -EINVAL;
 579 }
 580
 581 static struct dm_space_map bootstrap_ops = {
 582         .destroy = sm_bootstrap_destroy,
 583         .extend = sm_bootstrap_extend,
 584         .get_nr_blocks = sm_bootstrap_get_nr_blocks,
 585         .get_nr_free = sm_bootstrap_get_nr_free,
 586         .get_count = sm_bootstrap_get_count,
 587         .count_is_more_than_one = sm_bootstrap_count_is_more_than_one,
 588         .set_count = sm_bootstrap_set_count,
 589         .inc_block = sm_bootstrap_inc_block,
 590         .dec_block = sm_bootstrap_dec_block,
 591         .new_block = sm_bootstrap_new_block,
 592         .commit = sm_bootstrap_commit,
 593         .root_size = sm_bootstrap_root_size,
 594         .copy_root = sm_bootstrap_copy_root,
 595         .register_threshold_callback = NULL
 596 };
 597
 598 /*----------------------------------------------------------------*/
 599
 600 static int sm_metadata_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
 601 {
 602         int r, i;
 603         enum allocation_event ev;
 604         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 605         dm_block_t old_len = smm->ll.nr_blocks;
 606
 607         /*
 608          * Flick into a mode where all blocks get allocated in the new area.
 609          */
 610         smm->begin = old_len;
 611         memcpy(sm, &bootstrap_ops, sizeof(*sm));
 612
 613         /*
 614          * Extend.
 615          */
 616         r = sm_ll_extend(&smm->ll, extra_blocks);
 617         if (r)
 618                 goto out;
 619
 620         /*
 621          * We repeatedly increment then commit until the commit doesn't
 622          * allocate any new blocks.
 623          */
 624         do {
 625                 for (i = old_len; !r && i < smm->begin; i++) {
 626                         r = sm_ll_inc(&smm->ll, i, &ev);
 627                         if (r)
 628                                 goto out;
 629                 }
 630                 old_len = smm->begin;
 631
 632                 r = sm_ll_commit(&smm->ll);
 633                 if (r)
 634                         goto out;
 635
 636         } while (old_len != smm->begin);
 637
 638 out:
 639         /*
 640          * Switch back to normal behaviour.
 641          */
 642         memcpy(sm, &ops, sizeof(*sm));
 643         return r;
 644 }
 645
 646 /*----------------------------------------------------------------*/
 647
 648 struct dm_space_map *dm_sm_metadata_init(void)
 649 {
 650         struct sm_metadata *smm;
 651
 652         smm = kmalloc(sizeof(*smm), GFP_KERNEL);
 653         if (!smm)
 654                 return ERR_PTR(-ENOMEM);
 655
 656         memcpy(&smm->sm, &ops, sizeof(smm->sm));
 657
 658         return &smm->sm;
 659 }
 660
 661 int dm_sm_metadata_create(struct dm_space_map *sm,
 662                           struct dm_transaction_manager *tm,
 663                           dm_block_t nr_blocks,
 664                           dm_block_t superblock)
 665 {
 666         int r;
 667         dm_block_t i;
 668         enum allocation_event ev;
 669         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 670
 671         smm->begin = superblock + 1;
 672         smm->recursion_count = 0;
 673         smm->allocated_this_transaction = 0;
 674         smm->nr_uncommitted = 0;
 675         threshold_init(&smm->threshold);
 676
 677         memcpy(&smm->sm, &bootstrap_ops, sizeof(smm->sm));
 678
 679         r = sm_ll_new_metadata(&smm->ll, tm);
 680         if (r)
 681                 return r;
 682
 683         r = sm_ll_extend(&smm->ll, nr_blocks);
 684         if (r)
 685                 return r;
 686
 687         memcpy(&smm->sm, &ops, sizeof(smm->sm));
 688
 689         /*
 690          * Now we need to update the newly created data structures with the
 691          * allocated blocks that they were built from.
 692          */
 693         for (i = superblock; !r && i < smm->begin; i++)
 694                 r = sm_ll_inc(&smm->ll, i, &ev);
 695
 696         if (r)
 697                 return r;
 698
 699         return sm_metadata_commit(sm);
 700 }
 701
 702 int dm_sm_metadata_open(struct dm_space_map *sm,
 703                         struct dm_transaction_manager *tm,
 704                         void *root_le, size_t len)
 705 {
 706         int r;
 707         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 708
 709         r = sm_ll_open_metadata(&smm->ll, tm, root_le, len);
 710         if (r)
 711                 return r;
 712
 713         smm->begin = 0;
 714         smm->recursion_count = 0;
 715         smm->allocated_this_transaction = 0;
 716         smm->nr_uncommitted = 0;
 717         threshold_init(&smm->threshold);
 718
 719         memcpy(&smm->old_ll, &smm->ll, sizeof(smm->old_ll));
 720         return 0;
 721 }