drivers/md/dm-cache-target.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2012 Red Hat. All rights reserved.
   4  *
   5  * This file is released under the GPL.
   6  */
   7
   8 #include "dm.h"
   9 #include "dm-bio-prison-v2.h"
  10 #include "dm-bio-record.h"
  11 #include "dm-cache-metadata.h"
  12 #include "dm-io-tracker.h"
  13
  14 #include <linux/dm-io.h>
  15 #include <linux/dm-kcopyd.h>
  16 #include <linux/jiffies.h>
  17 #include <linux/init.h>
  18 #include <linux/mempool.h>
  19 #include <linux/module.h>
  20 #include <linux/rwsem.h>
  21 #include <linux/slab.h>
  22 #include <linux/vmalloc.h>
  23
  24 #define DM_MSG_PREFIX "cache"
  25
  26 DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(cache_copy_throttle,
  27         "A percentage of time allocated for copying to and/or from cache");
  28
  29 /*----------------------------------------------------------------*/
  30
  31 /*
  32  * Glossary:
  33  *
  34  * oblock: index of an origin block
  35  * cblock: index of a cache block
  36  * promotion: movement of a block from origin to cache
  37  * demotion: movement of a block from cache to origin
  38  * migration: movement of a block between the origin and cache device,
  39  *            either direction
  40  */
  41
  42 /*----------------------------------------------------------------*/
  43
  44 /*
  45  * Represents a chunk of future work.  'input' allows continuations to pass
  46  * values between themselves, typically error values.
  47  */
  48 struct continuation {
  49         struct work_struct ws;
  50         blk_status_t input;
  51 };
  52
  53 static inline void init_continuation(struct continuation *k,
  54                                      void (*fn)(struct work_struct *))
  55 {
  56         INIT_WORK(&k->ws, fn);
  57         k->input = 0;
  58 }
  59
  60 static inline void queue_continuation(struct workqueue_struct *wq,
  61                                       struct continuation *k)
  62 {
  63         queue_work(wq, &k->ws);
  64 }
  65
  66 /*----------------------------------------------------------------*/
  67
  68 /*
  69  * The batcher collects together pieces of work that need a particular
  70  * operation to occur before they can proceed (typically a commit).
  71  */
  72 struct batcher {
  73         /*
  74          * The operation that everyone is waiting for.
  75          */
  76         blk_status_t (*commit_op)(void *context);
  77         void *commit_context;
  78
  79         /*
  80          * This is how bios should be issued once the commit op is complete
  81          * (accounted_request).
  82          */
  83         void (*issue_op)(struct bio *bio, void *context);
  84         void *issue_context;
  85
  86         /*
  87          * Queued work gets put on here after commit.
  88          */
  89         struct workqueue_struct *wq;
  90
  91         spinlock_t lock;
  92         struct list_head work_items;
  93         struct bio_list bios;
  94         struct work_struct commit_work;
  95
  96         bool commit_scheduled;
  97 };
  98
  99 static void __commit(struct work_struct *_ws)
 100 {
 101         struct batcher *b = container_of(_ws, struct batcher, commit_work);
 102         blk_status_t r;
 103         struct list_head work_items;
 104         struct work_struct *ws, *tmp;
 105         struct continuation *k;
 106         struct bio *bio;
 107         struct bio_list bios;
 108
 109         INIT_LIST_HEAD(&work_items);
 110         bio_list_init(&bios);
 111
 112         /*
 113          * We have to grab these before the commit_op to avoid a race
 114          * condition.
 115          */
 116         spin_lock_irq(&b->lock);
 117         list_splice_init(&b->work_items, &work_items);
 118         bio_list_merge(&bios, &b->bios);
 119         bio_list_init(&b->bios);
 120         b->commit_scheduled = false;
 121         spin_unlock_irq(&b->lock);
 122
 123         r = b->commit_op(b->commit_context);
 124
 125         list_for_each_entry_safe(ws, tmp, &work_items, entry) {
 126                 k = container_of(ws, struct continuation, ws);
 127                 k->input = r;
 128                 INIT_LIST_HEAD(&ws->entry); /* to avoid a WARN_ON */
 129                 queue_work(b->wq, ws);
 130         }
 131
 132         while ((bio = bio_list_pop(&bios))) {
 133                 if (r) {
 134                         bio->bi_status = r;
 135                         bio_endio(bio);
 136                 } else
 137                         b->issue_op(bio, b->issue_context);
 138         }
 139 }
 140
 141 static void batcher_init(struct batcher *b,
 142                          blk_status_t (*commit_op)(void *),
 143                          void *commit_context,
 144                          void (*issue_op)(struct bio *bio, void *),
 145                          void *issue_context,
 146                          struct workqueue_struct *wq)
 147 {
 148         b->commit_op = commit_op;
 149         b->commit_context = commit_context;
 150         b->issue_op = issue_op;
 151         b->issue_context = issue_context;
 152         b->wq = wq;
 153
 154         spin_lock_init(&b->lock);
 155         INIT_LIST_HEAD(&b->work_items);
 156         bio_list_init(&b->bios);
 157         INIT_WORK(&b->commit_work, __commit);
 158         b->commit_scheduled = false;
 159 }
 160
 161 static void async_commit(struct batcher *b)
 162 {
 163         queue_work(b->wq, &b->commit_work);
 164 }
 165
 166 static void continue_after_commit(struct batcher *b, struct continuation *k)
 167 {
 168         bool commit_scheduled;
 169
 170         spin_lock_irq(&b->lock);
 171         commit_scheduled = b->commit_scheduled;
 172         list_add_tail(&k->ws.entry, &b->work_items);
 173         spin_unlock_irq(&b->lock);
 174
 175         if (commit_scheduled)
 176                 async_commit(b);
 177 }
 178
 179 /*
 180  * Bios are errored if commit failed.
 181  */
 182 static void issue_after_commit(struct batcher *b, struct bio *bio)
 183 {
 184         bool commit_scheduled;
 185
 186         spin_lock_irq(&b->lock);
 187         commit_scheduled = b->commit_scheduled;
 188         bio_list_add(&b->bios, bio);
 189         spin_unlock_irq(&b->lock);
 190
 191         if (commit_scheduled)
 192                 async_commit(b);
 193 }
 194
 195 /*
 196  * Call this if some urgent work is waiting for the commit to complete.
 197  */
 198 static void schedule_commit(struct batcher *b)
 199 {
 200         bool immediate;
 201
 202         spin_lock_irq(&b->lock);
 203         immediate = !list_empty(&b->work_items) || !bio_list_empty(&b->bios);
 204         b->commit_scheduled = true;
 205         spin_unlock_irq(&b->lock);
 206
 207         if (immediate)
 208                 async_commit(b);
 209 }
 210
 211 /*
 212  * There are a couple of places where we let a bio run, but want to do some
 213  * work before calling its endio function.  We do this by temporarily
 214  * changing the endio fn.
 215  */
 216 struct dm_hook_info {
 217         bio_end_io_t *bi_end_io;
 218 };
 219
 220 static void dm_hook_bio(struct dm_hook_info *h, struct bio *bio,
 221                         bio_end_io_t *bi_end_io, void *bi_private)
 222 {
 223         h->bi_end_io = bio->bi_end_io;
 224
 225         bio->bi_end_io = bi_end_io;
 226         bio->bi_private = bi_private;
 227 }
 228
 229 static void dm_unhook_bio(struct dm_hook_info *h, struct bio *bio)
 230 {
 231         bio->bi_end_io = h->bi_end_io;
 232 }
 233
 234 /*----------------------------------------------------------------*/
 235
 236 #define MIGRATION_POOL_SIZE 128
 237 #define COMMIT_PERIOD HZ
 238 #define MIGRATION_COUNT_WINDOW 10
 239
 240 /*
 241  * The block size of the device holding cache data must be
 242  * between 32KB and 1GB.
 243  */
 244 #define DATA_DEV_BLOCK_SIZE_MIN_SECTORS (32 * 1024 >> SECTOR_SHIFT)
 245 #define DATA_DEV_BLOCK_SIZE_MAX_SECTORS (1024 * 1024 * 1024 >> SECTOR_SHIFT)
 246
 247 enum cache_metadata_mode {
 248         CM_WRITE,               /* metadata may be changed */
 249         CM_READ_ONLY,           /* metadata may not be changed */
 250         CM_FAIL
 251 };
 252
 253 enum cache_io_mode {
 254         /*
 255          * Data is written to cached blocks only.  These blocks are marked
 256          * dirty.  If you lose the cache device you will lose data.
 257          * Potential performance increase for both reads and writes.
 258          */
 259         CM_IO_WRITEBACK,
 260
 261         /*
 262          * Data is written to both cache and origin.  Blocks are never
 263          * dirty.  Potential performance benfit for reads only.
 264          */
 265         CM_IO_WRITETHROUGH,
 266
 267         /*
 268          * A degraded mode useful for various cache coherency situations
 269          * (eg, rolling back snapshots).  Reads and writes always go to the
 270          * origin.  If a write goes to a cached oblock, then the cache
 271          * block is invalidated.
 272          */
 273         CM_IO_PASSTHROUGH
 274 };
 275
 276 struct cache_features {
 277         enum cache_metadata_mode mode;
 278         enum cache_io_mode io_mode;
 279         unsigned int metadata_version;
 280         bool discard_passdown:1;
 281 };
 282
 283 struct cache_stats {
 284         atomic_t read_hit;
 285         atomic_t read_miss;
 286         atomic_t write_hit;
 287         atomic_t write_miss;
 288         atomic_t demotion;
 289         atomic_t promotion;
 290         atomic_t writeback;
 291         atomic_t copies_avoided;
 292         atomic_t cache_cell_clash;
 293         atomic_t commit_count;
 294         atomic_t discard_count;
 295 };
 296
 297 struct cache {
 298         struct dm_target *ti;
 299         spinlock_t lock;
 300
 301         /*
 302          * Fields for converting from sectors to blocks.
 303          */
 304         int sectors_per_block_shift;
 305         sector_t sectors_per_block;
 306
 307         struct dm_cache_metadata *cmd;
 308
 309         /*
 310          * Metadata is written to this device.
 311          */
 312         struct dm_dev *metadata_dev;
 313
 314         /*
 315          * The slower of the two data devices.  Typically a spindle.
 316          */
 317         struct dm_dev *origin_dev;
 318
 319         /*
 320          * The faster of the two data devices.  Typically an SSD.
 321          */
 322         struct dm_dev *cache_dev;
 323
 324         /*
 325          * Size of the origin device in _complete_ blocks and native sectors.
 326          */
 327         dm_oblock_t origin_blocks;
 328         sector_t origin_sectors;
 329
 330         /*
 331          * Size of the cache device in blocks.
 332          */
 333         dm_cblock_t cache_size;
 334
 335         /*
 336          * Invalidation fields.
 337          */
 338         spinlock_t invalidation_lock;
 339         struct list_head invalidation_requests;
 340
 341         sector_t migration_threshold;
 342         wait_queue_head_t migration_wait;
 343         atomic_t nr_allocated_migrations;
 344
 345         /*
 346          * The number of in flight migrations that are performing
 347          * background io. eg, promotion, writeback.
 348          */
 349         atomic_t nr_io_migrations;
 350
 351         struct bio_list deferred_bios;
 352
 353         struct rw_semaphore quiesce_lock;
 354
 355         /*
 356          * origin_blocks entries, discarded if set.
 357          */
 358         dm_dblock_t discard_nr_blocks;
 359         unsigned long *discard_bitset;
 360         uint32_t discard_block_size; /* a power of 2 times sectors per block */
 361
 362         /*
 363          * Rather than reconstructing the table line for the status we just
 364          * save it and regurgitate.
 365          */
 366         unsigned int nr_ctr_args;
 367         const char **ctr_args;
 368
 369         struct dm_kcopyd_client *copier;
 370         struct work_struct deferred_bio_worker;
 371         struct work_struct migration_worker;
 372         struct workqueue_struct *wq;
 373         struct delayed_work waker;
 374         struct dm_bio_prison_v2 *prison;
 375
 376         /*
 377          * cache_size entries, dirty if set
 378          */
 379         unsigned long *dirty_bitset;
 380         atomic_t nr_dirty;
 381
 382         unsigned int policy_nr_args;
 383         struct dm_cache_policy *policy;
 384
 385         /*
 386          * Cache features such as write-through.
 387          */
 388         struct cache_features features;
 389
 390         struct cache_stats stats;
 391
 392         bool need_tick_bio:1;
 393         bool sized:1;
 394         bool invalidate:1;
 395         bool commit_requested:1;
 396         bool loaded_mappings:1;
 397         bool loaded_discards:1;
 398
 399         struct rw_semaphore background_work_lock;
 400
 401         struct batcher committer;
 402         struct work_struct commit_ws;
 403
 404         struct dm_io_tracker tracker;
 405
 406         mempool_t migration_pool;
 407
 408         struct bio_set bs;
 409 };
 410
 411 struct per_bio_data {
 412         bool tick:1;
 413         unsigned int req_nr:2;
 414         struct dm_bio_prison_cell_v2 *cell;
 415         struct dm_hook_info hook_info;
 416         sector_t len;
 417 };
 418
 419 struct dm_cache_migration {
 420         struct continuation k;
 421         struct cache *cache;
 422
 423         struct policy_work *op;
 424         struct bio *overwrite_bio;
 425         struct dm_bio_prison_cell_v2 *cell;
 426
 427         dm_cblock_t invalidate_cblock;
 428         dm_oblock_t invalidate_oblock;
 429 };
 430
 431 /*----------------------------------------------------------------*/
 432
 433 static bool writethrough_mode(struct cache *cache)
 434 {
 435         return cache->features.io_mode == CM_IO_WRITETHROUGH;
 436 }
 437
 438 static bool writeback_mode(struct cache *cache)
 439 {
 440         return cache->features.io_mode == CM_IO_WRITEBACK;
 441 }
 442
 443 static inline bool passthrough_mode(struct cache *cache)
 444 {
 445         return unlikely(cache->features.io_mode == CM_IO_PASSTHROUGH);
 446 }
 447
 448 /*----------------------------------------------------------------*/
 449
 450 static void wake_deferred_bio_worker(struct cache *cache)
 451 {
 452         queue_work(cache->wq, &cache->deferred_bio_worker);
 453 }
 454
 455 static void wake_migration_worker(struct cache *cache)
 456 {
 457         if (passthrough_mode(cache))
 458                 return;
 459
 460         queue_work(cache->wq, &cache->migration_worker);
 461 }
 462
 463 /*----------------------------------------------------------------*/
 464
 465 static struct dm_bio_prison_cell_v2 *alloc_prison_cell(struct cache *cache)
 466 {
 467         return dm_bio_prison_alloc_cell_v2(cache->prison, GFP_NOIO);
 468 }
 469
 470 static void free_prison_cell(struct cache *cache, struct dm_bio_prison_cell_v2 *cell)
 471 {
 472         dm_bio_prison_free_cell_v2(cache->prison, cell);
 473 }
 474
 475 static struct dm_cache_migration *alloc_migration(struct cache *cache)
 476 {
 477         struct dm_cache_migration *mg;
 478
 479         mg = mempool_alloc(&cache->migration_pool, GFP_NOIO);
 480
 481         memset(mg, 0, sizeof(*mg));
 482
 483         mg->cache = cache;
 484         atomic_inc(&cache->nr_allocated_migrations);
 485
 486         return mg;
 487 }
 488
 489 static void free_migration(struct dm_cache_migration *mg)
 490 {
 491         struct cache *cache = mg->cache;
 492
 493         if (atomic_dec_and_test(&cache->nr_allocated_migrations))
 494                 wake_up(&cache->migration_wait);
 495
 496         mempool_free(mg, &cache->migration_pool);
 497 }
 498
 499 /*----------------------------------------------------------------*/
 500
 501 static inline dm_oblock_t oblock_succ(dm_oblock_t b)
 502 {
 503         return to_oblock(from_oblock(b) + 1ull);
 504 }
 505
 506 static void build_key(dm_oblock_t begin, dm_oblock_t end, struct dm_cell_key_v2 *key)
 507 {
 508         key->virtual = 0;
 509         key->dev = 0;
 510         key->block_begin = from_oblock(begin);
 511         key->block_end = from_oblock(end);
 512 }
 513
 514 /*
 515  * We have two lock levels.  Level 0, which is used to prevent WRITEs, and
 516  * level 1 which prevents *both* READs and WRITEs.
 517  */
 518 #define WRITE_LOCK_LEVEL 0
 519 #define READ_WRITE_LOCK_LEVEL 1
 520
 521 static unsigned int lock_level(struct bio *bio)
 522 {
 523         return bio_data_dir(bio) == WRITE ?
 524                 WRITE_LOCK_LEVEL :
 525                 READ_WRITE_LOCK_LEVEL;
 526 }
 527
 528 /*
 529  *--------------------------------------------------------------
 530  * Per bio data
 531  *--------------------------------------------------------------
 532  */
 533
 534 static struct per_bio_data *get_per_bio_data(struct bio *bio)
 535 {
 536         struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
 537
 538         BUG_ON(!pb);
 539         return pb;
 540 }
 541
 542 static struct per_bio_data *init_per_bio_data(struct bio *bio)
 543 {
 544         struct per_bio_data *pb = get_per_bio_data(bio);
 545
 546         pb->tick = false;
 547         pb->req_nr = dm_bio_get_target_bio_nr(bio);
 548         pb->cell = NULL;
 549         pb->len = 0;
 550
 551         return pb;
 552 }
 553
 554 /*----------------------------------------------------------------*/
 555
 556 static void defer_bio(struct cache *cache, struct bio *bio)
 557 {
 558         spin_lock_irq(&cache->lock);
 559         bio_list_add(&cache->deferred_bios, bio);
 560         spin_unlock_irq(&cache->lock);
 561
 562         wake_deferred_bio_worker(cache);
 563 }
 564
 565 static void defer_bios(struct cache *cache, struct bio_list *bios)
 566 {
 567         spin_lock_irq(&cache->lock);
 568         bio_list_merge(&cache->deferred_bios, bios);
 569         bio_list_init(bios);
 570         spin_unlock_irq(&cache->lock);
 571
 572         wake_deferred_bio_worker(cache);
 573 }
 574
 575 /*----------------------------------------------------------------*/
 576
 577 static bool bio_detain_shared(struct cache *cache, dm_oblock_t oblock, struct bio *bio)
 578 {
 579         bool r;
 580         struct per_bio_data *pb;
 581         struct dm_cell_key_v2 key;
 582         dm_oblock_t end = to_oblock(from_oblock(oblock) + 1ULL);
 583         struct dm_bio_prison_cell_v2 *cell_prealloc, *cell;
 584
 585         cell_prealloc = alloc_prison_cell(cache); /* FIXME: allow wait if calling from worker */
 586
 587         build_key(oblock, end, &key);
 588         r = dm_cell_get_v2(cache->prison, &key, lock_level(bio), bio, cell_prealloc, &cell);
 589         if (!r) {
 590                 /*
 591                  * Failed to get the lock.
 592                  */
 593                 free_prison_cell(cache, cell_prealloc);
 594                 return r;
 595         }
 596
 597         if (cell != cell_prealloc)
 598                 free_prison_cell(cache, cell_prealloc);
 599
 600         pb = get_per_bio_data(bio);
 601         pb->cell = cell;
 602
 603         return r;
 604 }
 605
 606 /*----------------------------------------------------------------*/
 607
 608 static bool is_dirty(struct cache *cache, dm_cblock_t b)
 609 {
 610         return test_bit(from_cblock(b), cache->dirty_bitset);
 611 }
 612
 613 static void set_dirty(struct cache *cache, dm_cblock_t cblock)
 614 {
 615         if (!test_and_set_bit(from_cblock(cblock), cache->dirty_bitset)) {
 616                 atomic_inc(&cache->nr_dirty);
 617                 policy_set_dirty(cache->policy, cblock);
 618         }
 619 }
 620
 621 /*
 622  * These two are called when setting after migrations to force the policy
 623  * and dirty bitset to be in sync.
 624  */
 625 static void force_set_dirty(struct cache *cache, dm_cblock_t cblock)
 626 {
 627         if (!test_and_set_bit(from_cblock(cblock), cache->dirty_bitset))
 628                 atomic_inc(&cache->nr_dirty);
 629         policy_set_dirty(cache->policy, cblock);
 630 }
 631
 632 static void force_clear_dirty(struct cache *cache, dm_cblock_t cblock)
 633 {
 634         if (test_and_clear_bit(from_cblock(cblock), cache->dirty_bitset)) {
 635                 if (atomic_dec_return(&cache->nr_dirty) == 0)
 636                         dm_table_event(cache->ti->table);
 637         }
 638
 639         policy_clear_dirty(cache->policy, cblock);
 640 }
 641
 642 /*----------------------------------------------------------------*/
 643
 644 static bool block_size_is_power_of_two(struct cache *cache)
 645 {
 646         return cache->sectors_per_block_shift >= 0;
 647 }
 648
 649 static dm_block_t block_div(dm_block_t b, uint32_t n)
 650 {
 651         do_div(b, n);
 652
 653         return b;
 654 }
 655
 656 static dm_block_t oblocks_per_dblock(struct cache *cache)
 657 {
 658         dm_block_t oblocks = cache->discard_block_size;
 659
 660         if (block_size_is_power_of_two(cache))
 661                 oblocks >>= cache->sectors_per_block_shift;
 662         else
 663                 oblocks = block_div(oblocks, cache->sectors_per_block);
 664
 665         return oblocks;
 666 }
 667
 668 static dm_dblock_t oblock_to_dblock(struct cache *cache, dm_oblock_t oblock)
 669 {
 670         return to_dblock(block_div(from_oblock(oblock),
 671                                    oblocks_per_dblock(cache)));
 672 }
 673
 674 static void set_discard(struct cache *cache, dm_dblock_t b)
 675 {
 676         BUG_ON(from_dblock(b) >= from_dblock(cache->discard_nr_blocks));
 677         atomic_inc(&cache->stats.discard_count);
 678
 679         spin_lock_irq(&cache->lock);
 680         set_bit(from_dblock(b), cache->discard_bitset);
 681         spin_unlock_irq(&cache->lock);
 682 }
 683
 684 static void clear_discard(struct cache *cache, dm_dblock_t b)
 685 {
 686         spin_lock_irq(&cache->lock);
 687         clear_bit(from_dblock(b), cache->discard_bitset);
 688         spin_unlock_irq(&cache->lock);
 689 }
 690
 691 static bool is_discarded(struct cache *cache, dm_dblock_t b)
 692 {
 693         int r;
 694
 695         spin_lock_irq(&cache->lock);
 696         r = test_bit(from_dblock(b), cache->discard_bitset);
 697         spin_unlock_irq(&cache->lock);
 698
 699         return r;
 700 }
 701
 702 static bool is_discarded_oblock(struct cache *cache, dm_oblock_t b)
 703 {
 704         int r;
 705
 706         spin_lock_irq(&cache->lock);
 707         r = test_bit(from_dblock(oblock_to_dblock(cache, b)),
 708                      cache->discard_bitset);
 709         spin_unlock_irq(&cache->lock);
 710
 711         return r;
 712 }
 713
 714 /*
 715  * -------------------------------------------------------------
 716  * Remapping
 717  *--------------------------------------------------------------
 718  */
 719 static void remap_to_origin(struct cache *cache, struct bio *bio)
 720 {
 721         bio_set_dev(bio, cache->origin_dev->bdev);
 722 }
 723
 724 static void remap_to_cache(struct cache *cache, struct bio *bio,
 725                            dm_cblock_t cblock)
 726 {
 727         sector_t bi_sector = bio->bi_iter.bi_sector;
 728         sector_t block = from_cblock(cblock);
 729
 730         bio_set_dev(bio, cache->cache_dev->bdev);
 731         if (!block_size_is_power_of_two(cache))
 732                 bio->bi_iter.bi_sector =
 733                         (block * cache->sectors_per_block) +
 734                         sector_div(bi_sector, cache->sectors_per_block);
 735         else
 736                 bio->bi_iter.bi_sector =
 737                         (block << cache->sectors_per_block_shift) |
 738                         (bi_sector & (cache->sectors_per_block - 1));
 739 }
 740
 741 static void check_if_tick_bio_needed(struct cache *cache, struct bio *bio)
 742 {
 743         struct per_bio_data *pb;
 744
 745         spin_lock_irq(&cache->lock);
 746         if (cache->need_tick_bio && !op_is_flush(bio->bi_opf) &&
 747             bio_op(bio) != REQ_OP_DISCARD) {
 748                 pb = get_per_bio_data(bio);
 749                 pb->tick = true;
 750                 cache->need_tick_bio = false;
 751         }
 752         spin_unlock_irq(&cache->lock);
 753 }
 754
 755 static void remap_to_origin_clear_discard(struct cache *cache, struct bio *bio,
 756                                           dm_oblock_t oblock)
 757 {
 758         // FIXME: check_if_tick_bio_needed() is called way too much through this interface
 759         check_if_tick_bio_needed(cache, bio);
 760         remap_to_origin(cache, bio);
 761         if (bio_data_dir(bio) == WRITE)
 762                 clear_discard(cache, oblock_to_dblock(cache, oblock));
 763 }
 764
 765 static void remap_to_cache_dirty(struct cache *cache, struct bio *bio,
 766                                  dm_oblock_t oblock, dm_cblock_t cblock)
 767 {
 768         check_if_tick_bio_needed(cache, bio);
 769         remap_to_cache(cache, bio, cblock);
 770         if (bio_data_dir(bio) == WRITE) {
 771                 set_dirty(cache, cblock);
 772                 clear_discard(cache, oblock_to_dblock(cache, oblock));
 773         }
 774 }
 775
 776 static dm_oblock_t get_bio_block(struct cache *cache, struct bio *bio)
 777 {
 778         sector_t block_nr = bio->bi_iter.bi_sector;
 779
 780         if (!block_size_is_power_of_two(cache))
 781                 (void) sector_div(block_nr, cache->sectors_per_block);
 782         else
 783                 block_nr >>= cache->sectors_per_block_shift;
 784
 785         return to_oblock(block_nr);
 786 }
 787
 788 static bool accountable_bio(struct cache *cache, struct bio *bio)
 789 {
 790         return bio_op(bio) != REQ_OP_DISCARD;
 791 }
 792
 793 static void accounted_begin(struct cache *cache, struct bio *bio)
 794 {
 795         struct per_bio_data *pb;
 796
 797         if (accountable_bio(cache, bio)) {
 798                 pb = get_per_bio_data(bio);
 799                 pb->len = bio_sectors(bio);
 800                 dm_iot_io_begin(&cache->tracker, pb->len);
 801         }
 802 }
 803
 804 static void accounted_complete(struct cache *cache, struct bio *bio)
 805 {
 806         struct per_bio_data *pb = get_per_bio_data(bio);
 807
 808         dm_iot_io_end(&cache->tracker, pb->len);
 809 }
 810
 811 static void accounted_request(struct cache *cache, struct bio *bio)
 812 {
 813         accounted_begin(cache, bio);
 814         dm_submit_bio_remap(bio, NULL);
 815 }
 816
 817 static void issue_op(struct bio *bio, void *context)
 818 {
 819         struct cache *cache = context;
 820
 821         accounted_request(cache, bio);
 822 }
 823
 824 /*
 825  * When running in writethrough mode we need to send writes to clean blocks
 826  * to both the cache and origin devices.  Clone the bio and send them in parallel.
 827  */
 828 static void remap_to_origin_and_cache(struct cache *cache, struct bio *bio,
 829                                       dm_oblock_t oblock, dm_cblock_t cblock)
 830 {
 831         struct bio *origin_bio = bio_alloc_clone(cache->origin_dev->bdev, bio,
 832                                                  GFP_NOIO, &cache->bs);
 833
 834         BUG_ON(!origin_bio);
 835
 836         bio_chain(origin_bio, bio);
 837
 838         if (bio_data_dir(origin_bio) == WRITE)
 839                 clear_discard(cache, oblock_to_dblock(cache, oblock));
 840         submit_bio(origin_bio);
 841
 842         remap_to_cache(cache, bio, cblock);
 843 }
 844
 845 /*
 846  *--------------------------------------------------------------
 847  * Failure modes
 848  *--------------------------------------------------------------
 849  */
 850 static enum cache_metadata_mode get_cache_mode(struct cache *cache)
 851 {
 852         return cache->features.mode;
 853 }
 854
 855 static const char *cache_device_name(struct cache *cache)
 856 {
 857         return dm_table_device_name(cache->ti->table);
 858 }
 859
 860 static void notify_mode_switch(struct cache *cache, enum cache_metadata_mode mode)
 861 {
 862         static const char *descs[] = {
 863                 "write",
 864                 "read-only",
 865                 "fail"
 866         };
 867
 868         dm_table_event(cache->ti->table);
 869         DMINFO("%s: switching cache to %s mode",
 870                cache_device_name(cache), descs[(int)mode]);
 871 }
 872
 873 static void set_cache_mode(struct cache *cache, enum cache_metadata_mode new_mode)
 874 {
 875         bool needs_check;
 876         enum cache_metadata_mode old_mode = get_cache_mode(cache);
 877
 878         if (dm_cache_metadata_needs_check(cache->cmd, &needs_check)) {
 879                 DMERR("%s: unable to read needs_check flag, setting failure mode.",
 880                       cache_device_name(cache));
 881                 new_mode = CM_FAIL;
 882         }
 883
 884         if (new_mode == CM_WRITE && needs_check) {
 885                 DMERR("%s: unable to switch cache to write mode until repaired.",
 886                       cache_device_name(cache));
 887                 if (old_mode != new_mode)
 888                         new_mode = old_mode;
 889                 else
 890                         new_mode = CM_READ_ONLY;
 891         }
 892
 893         /* Never move out of fail mode */
 894         if (old_mode == CM_FAIL)
 895                 new_mode = CM_FAIL;
 896
 897         switch (new_mode) {
 898         case CM_FAIL:
 899         case CM_READ_ONLY:
 900                 dm_cache_metadata_set_read_only(cache->cmd);
 901                 break;
 902
 903         case CM_WRITE:
 904                 dm_cache_metadata_set_read_write(cache->cmd);
 905                 break;
 906         }
 907
 908         cache->features.mode = new_mode;
 909
 910         if (new_mode != old_mode)
 911                 notify_mode_switch(cache, new_mode);
 912 }
 913
 914 static void abort_transaction(struct cache *cache)
 915 {
 916         const char *dev_name = cache_device_name(cache);
 917
 918         if (get_cache_mode(cache) >= CM_READ_ONLY)
 919                 return;
 920
 921         DMERR_LIMIT("%s: aborting current metadata transaction", dev_name);
 922         if (dm_cache_metadata_abort(cache->cmd)) {
 923                 DMERR("%s: failed to abort metadata transaction", dev_name);
 924                 set_cache_mode(cache, CM_FAIL);
 925         }
 926
 927         if (dm_cache_metadata_set_needs_check(cache->cmd)) {
 928                 DMERR("%s: failed to set 'needs_check' flag in metadata", dev_name);
 929                 set_cache_mode(cache, CM_FAIL);
 930         }
 931 }
 932
 933 static void metadata_operation_failed(struct cache *cache, const char *op, int r)
 934 {
 935         DMERR_LIMIT("%s: metadata operation '%s' failed: error = %d",
 936                     cache_device_name(cache), op, r);
 937         abort_transaction(cache);
 938         set_cache_mode(cache, CM_READ_ONLY);
 939 }
 940
 941 /*----------------------------------------------------------------*/
 942
 943 static void load_stats(struct cache *cache)
 944 {
 945         struct dm_cache_statistics stats;
 946
 947         dm_cache_metadata_get_stats(cache->cmd, &stats);
 948         atomic_set(&cache->stats.read_hit, stats.read_hits);
 949         atomic_set(&cache->stats.read_miss, stats.read_misses);
 950         atomic_set(&cache->stats.write_hit, stats.write_hits);
 951         atomic_set(&cache->stats.write_miss, stats.write_misses);
 952 }
 953
 954 static void save_stats(struct cache *cache)
 955 {
 956         struct dm_cache_statistics stats;
 957
 958         if (get_cache_mode(cache) >= CM_READ_ONLY)
 959                 return;
 960
 961         stats.read_hits = atomic_read(&cache->stats.read_hit);
 962         stats.read_misses = atomic_read(&cache->stats.read_miss);
 963         stats.write_hits = atomic_read(&cache->stats.write_hit);
 964         stats.write_misses = atomic_read(&cache->stats.write_miss);
 965
 966         dm_cache_metadata_set_stats(cache->cmd, &stats);
 967 }
 968
 969 static void update_stats(struct cache_stats *stats, enum policy_operation op)
 970 {
 971         switch (op) {
 972         case POLICY_PROMOTE:
 973                 atomic_inc(&stats->promotion);
 974                 break;
 975
 976         case POLICY_DEMOTE:
 977                 atomic_inc(&stats->demotion);
 978                 break;
 979
 980         case POLICY_WRITEBACK:
 981                 atomic_inc(&stats->writeback);
 982                 break;
 983         }
 984 }
 985
 986 /*
 987  *---------------------------------------------------------------------
 988  * Migration processing
 989  *
 990  * Migration covers moving data from the origin device to the cache, or
 991  * vice versa.
 992  *---------------------------------------------------------------------
 993  */
 994 static void inc_io_migrations(struct cache *cache)
 995 {
 996         atomic_inc(&cache->nr_io_migrations);
 997 }
 998
 999 static void dec_io_migrations(struct cache *cache)
1000 {
1001         atomic_dec(&cache->nr_io_migrations);
1002 }
1003
1004 static bool discard_or_flush(struct bio *bio)
1005 {
1006         return bio_op(bio) == REQ_OP_DISCARD || op_is_flush(bio->bi_opf);
1007 }
1008
1009 static void calc_discard_block_range(struct cache *cache, struct bio *bio,
1010                                      dm_dblock_t *b, dm_dblock_t *e)
1011 {
1012         sector_t sb = bio->bi_iter.bi_sector;
1013         sector_t se = bio_end_sector(bio);
1014
1015         *b = to_dblock(dm_sector_div_up(sb, cache->discard_block_size));
1016
1017         if (se - sb < cache->discard_block_size)
1018                 *e = *b;
1019         else
1020                 *e = to_dblock(block_div(se, cache->discard_block_size));
1021 }
1022
1023 /*----------------------------------------------------------------*/
1024
1025 static void prevent_background_work(struct cache *cache)
1026 {
1027         lockdep_off();
1028         down_write(&cache->background_work_lock);
1029         lockdep_on();
1030 }
1031
1032 static void allow_background_work(struct cache *cache)
1033 {
1034         lockdep_off();
1035         up_write(&cache->background_work_lock);
1036         lockdep_on();
1037 }
1038
1039 static bool background_work_begin(struct cache *cache)
1040 {
1041         bool r;
1042
1043         lockdep_off();
1044         r = down_read_trylock(&cache->background_work_lock);
1045         lockdep_on();
1046
1047         return r;
1048 }
1049
1050 static void background_work_end(struct cache *cache)
1051 {
1052         lockdep_off();
1053         up_read(&cache->background_work_lock);
1054         lockdep_on();
1055 }
1056
1057 /*----------------------------------------------------------------*/
1058
1059 static bool bio_writes_complete_block(struct cache *cache, struct bio *bio)
1060 {
1061         return (bio_data_dir(bio) == WRITE) &&
1062                 (bio->bi_iter.bi_size == (cache->sectors_per_block << SECTOR_SHIFT));
1063 }
1064
1065 static bool optimisable_bio(struct cache *cache, struct bio *bio, dm_oblock_t block)
1066 {
1067         return writeback_mode(cache) &&
1068                 (is_discarded_oblock(cache, block) || bio_writes_complete_block(cache, bio));
1069 }
1070
1071 static void quiesce(struct dm_cache_migration *mg,
1072                     void (*continuation)(struct work_struct *))
1073 {
1074         init_continuation(&mg->k, continuation);
1075         dm_cell_quiesce_v2(mg->cache->prison, mg->cell, &mg->k.ws);
1076 }
1077
1078 static struct dm_cache_migration *ws_to_mg(struct work_struct *ws)
1079 {
1080         struct continuation *k = container_of(ws, struct continuation, ws);
1081
1082         return container_of(k, struct dm_cache_migration, k);
1083 }
1084
1085 static void copy_complete(int read_err, unsigned long write_err, void *context)
1086 {
1087         struct dm_cache_migration *mg = container_of(context, struct dm_cache_migration, k);
1088
1089         if (read_err || write_err)
1090                 mg->k.input = BLK_STS_IOERR;
1091
1092         queue_continuation(mg->cache->wq, &mg->k);
1093 }
1094
1095 static void copy(struct dm_cache_migration *mg, bool promote)
1096 {
1097         struct dm_io_region o_region, c_region;
1098         struct cache *cache = mg->cache;
1099
1100         o_region.bdev = cache->origin_dev->bdev;
1101         o_region.sector = from_oblock(mg->op->oblock) * cache->sectors_per_block;
1102         o_region.count = cache->sectors_per_block;
1103
1104         c_region.bdev = cache->cache_dev->bdev;
1105         c_region.sector = from_cblock(mg->op->cblock) * cache->sectors_per_block;
1106         c_region.count = cache->sectors_per_block;
1107
1108         if (promote)
1109                 dm_kcopyd_copy(cache->copier, &o_region, 1, &c_region, 0, copy_complete, &mg->k);
1110         else
1111                 dm_kcopyd_copy(cache->copier, &c_region, 1, &o_region, 0, copy_complete, &mg->k);
1112 }
1113
1114 static void bio_drop_shared_lock(struct cache *cache, struct bio *bio)
1115 {
1116         struct per_bio_data *pb = get_per_bio_data(bio);
1117
1118         if (pb->cell && dm_cell_put_v2(cache->prison, pb->cell))
1119                 free_prison_cell(cache, pb->cell);
1120         pb->cell = NULL;
1121 }
1122
1123 static void overwrite_endio(struct bio *bio)
1124 {
1125         struct dm_cache_migration *mg = bio->bi_private;
1126         struct cache *cache = mg->cache;
1127         struct per_bio_data *pb = get_per_bio_data(bio);
1128
1129         dm_unhook_bio(&pb->hook_info, bio);
1130
1131         if (bio->bi_status)
1132                 mg->k.input = bio->bi_status;
1133
1134         queue_continuation(cache->wq, &mg->k);
1135 }
1136
1137 static void overwrite(struct dm_cache_migration *mg,
1138                       void (*continuation)(struct work_struct *))
1139 {
1140         struct bio *bio = mg->overwrite_bio;
1141         struct per_bio_data *pb = get_per_bio_data(bio);
1142
1143         dm_hook_bio(&pb->hook_info, bio, overwrite_endio, mg);
1144
1145         /*
1146          * The overwrite bio is part of the copy operation, as such it does
1147          * not set/clear discard or dirty flags.
1148          */
1149         if (mg->op->op == POLICY_PROMOTE)
1150                 remap_to_cache(mg->cache, bio, mg->op->cblock);
1151         else
1152                 remap_to_origin(mg->cache, bio);
1153
1154         init_continuation(&mg->k, continuation);
1155         accounted_request(mg->cache, bio);
1156 }
1157
1158 /*
1159  * Migration steps:
1160  *
1161  * 1) exclusive lock preventing WRITEs
1162  * 2) quiesce
1163  * 3) copy or issue overwrite bio
1164  * 4) upgrade to exclusive lock preventing READs and WRITEs
1165  * 5) quiesce
1166  * 6) update metadata and commit
1167  * 7) unlock
1168  */
1169 static void mg_complete(struct dm_cache_migration *mg, bool success)
1170 {
1171         struct bio_list bios;
1172         struct cache *cache = mg->cache;
1173         struct policy_work *op = mg->op;
1174         dm_cblock_t cblock = op->cblock;
1175
1176         if (success)
1177                 update_stats(&cache->stats, op->op);
1178
1179         switch (op->op) {
1180         case POLICY_PROMOTE:
1181                 clear_discard(cache, oblock_to_dblock(cache, op->oblock));
1182                 policy_complete_background_work(cache->policy, op, success);
1183
1184                 if (mg->overwrite_bio) {
1185                         if (success)
1186                                 force_set_dirty(cache, cblock);
1187                         else if (mg->k.input)
1188                                 mg->overwrite_bio->bi_status = mg->k.input;
1189                         else
1190                                 mg->overwrite_bio->bi_status = BLK_STS_IOERR;
1191                         bio_endio(mg->overwrite_bio);
1192                 } else {
1193                         if (success)
1194                                 force_clear_dirty(cache, cblock);
1195                         dec_io_migrations(cache);
1196                 }
1197                 break;
1198
1199         case POLICY_DEMOTE:
1200                 /*
1201                  * We clear dirty here to update the nr_dirty counter.
1202                  */
1203                 if (success)
1204                         force_clear_dirty(cache, cblock);
1205                 policy_complete_background_work(cache->policy, op, success);
1206                 dec_io_migrations(cache);
1207                 break;
1208
1209         case POLICY_WRITEBACK:
1210                 if (success)
1211                         force_clear_dirty(cache, cblock);
1212                 policy_complete_background_work(cache->policy, op, success);
1213                 dec_io_migrations(cache);
1214                 break;
1215         }
1216
1217         bio_list_init(&bios);
1218         if (mg->cell) {
1219                 if (dm_cell_unlock_v2(cache->prison, mg->cell, &bios))
1220                         free_prison_cell(cache, mg->cell);
1221         }
1222
1223         free_migration(mg);
1224         defer_bios(cache, &bios);
1225         wake_migration_worker(cache);
1226
1227         background_work_end(cache);
1228 }
1229
1230 static void mg_success(struct work_struct *ws)
1231 {
1232         struct dm_cache_migration *mg = ws_to_mg(ws);
1233
1234         mg_complete(mg, mg->k.input == 0);
1235 }
1236
1237 static void mg_update_metadata(struct work_struct *ws)
1238 {
1239         int r;
1240         struct dm_cache_migration *mg = ws_to_mg(ws);
1241         struct cache *cache = mg->cache;
1242         struct policy_work *op = mg->op;
1243
1244         switch (op->op) {
1245         case POLICY_PROMOTE:
1246                 r = dm_cache_insert_mapping(cache->cmd, op->cblock, op->oblock);
1247                 if (r) {
1248                         DMERR_LIMIT("%s: migration failed; couldn't insert mapping",
1249                                     cache_device_name(cache));
1250                         metadata_operation_failed(cache, "dm_cache_insert_mapping", r);
1251
1252                         mg_complete(mg, false);
1253                         return;
1254                 }
1255                 mg_complete(mg, true);
1256                 break;
1257
1258         case POLICY_DEMOTE:
1259                 r = dm_cache_remove_mapping(cache->cmd, op->cblock);
1260                 if (r) {
1261                         DMERR_LIMIT("%s: migration failed; couldn't update on disk metadata",
1262                                     cache_device_name(cache));
1263                         metadata_operation_failed(cache, "dm_cache_remove_mapping", r);
1264
1265                         mg_complete(mg, false);
1266                         return;
1267                 }
1268
1269                 /*
1270                  * It would be nice if we only had to commit when a REQ_FLUSH
1271                  * comes through.  But there's one scenario that we have to
1272                  * look out for:
1273                  *
1274                  * - vblock x in a cache block
1275                  * - domotion occurs
1276                  * - cache block gets reallocated and over written
1277                  * - crash
1278                  *
1279                  * When we recover, because there was no commit the cache will
1280                  * rollback to having the data for vblock x in the cache block.
1281                  * But the cache block has since been overwritten, so it'll end
1282                  * up pointing to data that was never in 'x' during the history
1283                  * of the device.
1284                  *
1285                  * To avoid this issue we require a commit as part of the
1286                  * demotion operation.
1287                  */
1288                 init_continuation(&mg->k, mg_success);
1289                 continue_after_commit(&cache->committer, &mg->k);
1290                 schedule_commit(&cache->committer);
1291                 break;
1292
1293         case POLICY_WRITEBACK:
1294                 mg_complete(mg, true);
1295                 break;
1296         }
1297 }
1298
1299 static void mg_update_metadata_after_copy(struct work_struct *ws)
1300 {
1301         struct dm_cache_migration *mg = ws_to_mg(ws);
1302
1303         /*
1304          * Did the copy succeed?
1305          */
1306         if (mg->k.input)
1307                 mg_complete(mg, false);
1308         else
1309                 mg_update_metadata(ws);
1310 }
1311
1312 static void mg_upgrade_lock(struct work_struct *ws)
1313 {
1314         int r;
1315         struct dm_cache_migration *mg = ws_to_mg(ws);
1316
1317         /*
1318          * Did the copy succeed?
1319          */
1320         if (mg->k.input)
1321                 mg_complete(mg, false);
1322
1323         else {
1324                 /*
1325                  * Now we want the lock to prevent both reads and writes.
1326                  */
1327                 r = dm_cell_lock_promote_v2(mg->cache->prison, mg->cell,
1328                                             READ_WRITE_LOCK_LEVEL);
1329                 if (r < 0)
1330                         mg_complete(mg, false);
1331
1332                 else if (r)
1333                         quiesce(mg, mg_update_metadata);
1334
1335                 else
1336                         mg_update_metadata(ws);
1337         }
1338 }
1339
1340 static void mg_full_copy(struct work_struct *ws)
1341 {
1342         struct dm_cache_migration *mg = ws_to_mg(ws);
1343         struct cache *cache = mg->cache;
1344         struct policy_work *op = mg->op;
1345         bool is_policy_promote = (op->op == POLICY_PROMOTE);
1346
1347         if ((!is_policy_promote && !is_dirty(cache, op->cblock)) ||
1348             is_discarded_oblock(cache, op->oblock)) {
1349                 mg_upgrade_lock(ws);
1350                 return;
1351         }
1352
1353         init_continuation(&mg->k, mg_upgrade_lock);
1354         copy(mg, is_policy_promote);
1355 }
1356
1357 static void mg_copy(struct work_struct *ws)
1358 {
1359         struct dm_cache_migration *mg = ws_to_mg(ws);
1360
1361         if (mg->overwrite_bio) {
1362                 /*
1363                  * No exclusive lock was held when we last checked if the bio
1364                  * was optimisable.  So we have to check again in case things
1365                  * have changed (eg, the block may no longer be discarded).
1366                  */
1367                 if (!optimisable_bio(mg->cache, mg->overwrite_bio, mg->op->oblock)) {
1368                         /*
1369                          * Fallback to a real full copy after doing some tidying up.
1370                          */
1371                         bool rb = bio_detain_shared(mg->cache, mg->op->oblock, mg->overwrite_bio);
1372
1373                         BUG_ON(rb); /* An exclussive lock must _not_ be held for this block */
1374                         mg->overwrite_bio = NULL;
1375                         inc_io_migrations(mg->cache);
1376                         mg_full_copy(ws);
1377                         return;
1378                 }
1379
1380                 /*
1381                  * It's safe to do this here, even though it's new data
1382                  * because all IO has been locked out of the block.
1383                  *
1384                  * mg_lock_writes() already took READ_WRITE_LOCK_LEVEL
1385                  * so _not_ using mg_upgrade_lock() as continutation.
1386                  */
1387                 overwrite(mg, mg_update_metadata_after_copy);
1388
1389         } else
1390                 mg_full_copy(ws);
1391 }
1392
1393 static int mg_lock_writes(struct dm_cache_migration *mg)
1394 {
1395         int r;
1396         struct dm_cell_key_v2 key;
1397         struct cache *cache = mg->cache;
1398         struct dm_bio_prison_cell_v2 *prealloc;
1399
1400         prealloc = alloc_prison_cell(cache);
1401
1402         /*
1403          * Prevent writes to the block, but allow reads to continue.
1404          * Unless we're using an overwrite bio, in which case we lock
1405          * everything.
1406          */
1407         build_key(mg->op->oblock, oblock_succ(mg->op->oblock), &key);
1408         r = dm_cell_lock_v2(cache->prison, &key,
1409                             mg->overwrite_bio ?  READ_WRITE_LOCK_LEVEL : WRITE_LOCK_LEVEL,
1410                             prealloc, &mg->cell);
1411         if (r < 0) {
1412                 free_prison_cell(cache, prealloc);
1413                 mg_complete(mg, false);
1414                 return r;
1415         }
1416
1417         if (mg->cell != prealloc)
1418                 free_prison_cell(cache, prealloc);
1419
1420         if (r == 0)
1421                 mg_copy(&mg->k.ws);
1422         else
1423                 quiesce(mg, mg_copy);
1424
1425         return 0;
1426 }
1427
1428 static int mg_start(struct cache *cache, struct policy_work *op, struct bio *bio)
1429 {
1430         struct dm_cache_migration *mg;
1431
1432         if (!background_work_begin(cache)) {
1433                 policy_complete_background_work(cache->policy, op, false);
1434                 return -EPERM;
1435         }
1436
1437         mg = alloc_migration(cache);
1438
1439         mg->op = op;
1440         mg->overwrite_bio = bio;
1441
1442         if (!bio)
1443                 inc_io_migrations(cache);
1444
1445         return mg_lock_writes(mg);
1446 }
1447
1448 /*
1449  *--------------------------------------------------------------
1450  * invalidation processing
1451  *--------------------------------------------------------------
1452  */
1453
1454 static void invalidate_complete(struct dm_cache_migration *mg, bool success)
1455 {
1456         struct bio_list bios;
1457         struct cache *cache = mg->cache;
1458
1459         bio_list_init(&bios);
1460         if (dm_cell_unlock_v2(cache->prison, mg->cell, &bios))
1461                 free_prison_cell(cache, mg->cell);
1462
1463         if (!success && mg->overwrite_bio)
1464                 bio_io_error(mg->overwrite_bio);
1465
1466         free_migration(mg);
1467         defer_bios(cache, &bios);
1468
1469         background_work_end(cache);
1470 }
1471
1472 static void invalidate_completed(struct work_struct *ws)
1473 {
1474         struct dm_cache_migration *mg = ws_to_mg(ws);
1475
1476         invalidate_complete(mg, !mg->k.input);
1477 }
1478
1479 static int invalidate_cblock(struct cache *cache, dm_cblock_t cblock)
1480 {
1481         int r;
1482
1483         r = policy_invalidate_mapping(cache->policy, cblock);
1484         if (!r) {
1485                 r = dm_cache_remove_mapping(cache->cmd, cblock);
1486                 if (r) {
1487                         DMERR_LIMIT("%s: invalidation failed; couldn't update on disk metadata",
1488                                     cache_device_name(cache));
1489                         metadata_operation_failed(cache, "dm_cache_remove_mapping", r);
1490                 }
1491
1492         } else if (r == -ENODATA) {
1493                 /*
1494                  * Harmless, already unmapped.
1495                  */
1496                 r = 0;
1497
1498         } else
1499                 DMERR("%s: policy_invalidate_mapping failed", cache_device_name(cache));
1500
1501         return r;
1502 }
1503
1504 static void invalidate_remove(struct work_struct *ws)
1505 {
1506         int r;
1507         struct dm_cache_migration *mg = ws_to_mg(ws);
1508         struct cache *cache = mg->cache;
1509
1510         r = invalidate_cblock(cache, mg->invalidate_cblock);
1511         if (r) {
1512                 invalidate_complete(mg, false);
1513                 return;
1514         }
1515
1516         init_continuation(&mg->k, invalidate_completed);
1517         continue_after_commit(&cache->committer, &mg->k);
1518         remap_to_origin_clear_discard(cache, mg->overwrite_bio, mg->invalidate_oblock);
1519         mg->overwrite_bio = NULL;
1520         schedule_commit(&cache->committer);
1521 }
1522
1523 static int invalidate_lock(struct dm_cache_migration *mg)
1524 {
1525         int r;
1526         struct dm_cell_key_v2 key;
1527         struct cache *cache = mg->cache;
1528         struct dm_bio_prison_cell_v2 *prealloc;
1529
1530         prealloc = alloc_prison_cell(cache);
1531
1532         build_key(mg->invalidate_oblock, oblock_succ(mg->invalidate_oblock), &key);
1533         r = dm_cell_lock_v2(cache->prison, &key,
1534                             READ_WRITE_LOCK_LEVEL, prealloc, &mg->cell);
1535         if (r < 0) {
1536                 free_prison_cell(cache, prealloc);
1537                 invalidate_complete(mg, false);
1538                 return r;
1539         }
1540
1541         if (mg->cell != prealloc)
1542                 free_prison_cell(cache, prealloc);
1543
1544         if (r)
1545                 quiesce(mg, invalidate_remove);
1546
1547         else {
1548                 /*
1549                  * We can't call invalidate_remove() directly here because we
1550                  * might still be in request context.
1551                  */
1552                 init_continuation(&mg->k, invalidate_remove);
1553                 queue_work(cache->wq, &mg->k.ws);
1554         }
1555
1556         return 0;
1557 }
1558
1559 static int invalidate_start(struct cache *cache, dm_cblock_t cblock,
1560                             dm_oblock_t oblock, struct bio *bio)
1561 {
1562         struct dm_cache_migration *mg;
1563
1564         if (!background_work_begin(cache))
1565                 return -EPERM;
1566
1567         mg = alloc_migration(cache);
1568
1569         mg->overwrite_bio = bio;
1570         mg->invalidate_cblock = cblock;
1571         mg->invalidate_oblock = oblock;
1572
1573         return invalidate_lock(mg);
1574 }
1575
1576 /*
1577  *--------------------------------------------------------------
1578  * bio processing
1579  *--------------------------------------------------------------
1580  */
1581
1582 enum busy {
1583         IDLE,
1584         BUSY
1585 };
1586
1587 static enum busy spare_migration_bandwidth(struct cache *cache)
1588 {
1589         bool idle = dm_iot_idle_for(&cache->tracker, HZ);
1590         sector_t current_volume = (atomic_read(&cache->nr_io_migrations) + 1) *
1591                 cache->sectors_per_block;
1592
1593         if (idle && current_volume <= cache->migration_threshold)
1594                 return IDLE;
1595         else
1596                 return BUSY;
1597 }
1598
1599 static void inc_hit_counter(struct cache *cache, struct bio *bio)
1600 {
1601         atomic_inc(bio_data_dir(bio) == READ ?
1602                    &cache->stats.read_hit : &cache->stats.write_hit);
1603 }
1604
1605 static void inc_miss_counter(struct cache *cache, struct bio *bio)
1606 {
1607         atomic_inc(bio_data_dir(bio) == READ ?
1608                    &cache->stats.read_miss : &cache->stats.write_miss);
1609 }
1610
1611 /*----------------------------------------------------------------*/
1612
1613 static int map_bio(struct cache *cache, struct bio *bio, dm_oblock_t block,
1614                    bool *commit_needed)
1615 {
1616         int r, data_dir;
1617         bool rb, background_queued;
1618         dm_cblock_t cblock;
1619
1620         *commit_needed = false;
1621
1622         rb = bio_detain_shared(cache, block, bio);
1623         if (!rb) {
1624                 /*
1625                  * An exclusive lock is held for this block, so we have to
1626                  * wait.  We set the commit_needed flag so the current
1627                  * transaction will be committed asap, allowing this lock
1628                  * to be dropped.
1629                  */
1630                 *commit_needed = true;
1631                 return DM_MAPIO_SUBMITTED;
1632         }
1633
1634         data_dir = bio_data_dir(bio);
1635
1636         if (optimisable_bio(cache, bio, block)) {
1637                 struct policy_work *op = NULL;
1638
1639                 r = policy_lookup_with_work(cache->policy, block, &cblock, data_dir, true, &op);
1640                 if (unlikely(r && r != -ENOENT)) {
1641                         DMERR_LIMIT("%s: policy_lookup_with_work() failed with r = %d",
1642                                     cache_device_name(cache), r);
1643                         bio_io_error(bio);
1644                         return DM_MAPIO_SUBMITTED;
1645                 }
1646
1647                 if (r == -ENOENT && op) {
1648                         bio_drop_shared_lock(cache, bio);
1649                         BUG_ON(op->op != POLICY_PROMOTE);
1650                         mg_start(cache, op, bio);
1651                         return DM_MAPIO_SUBMITTED;
1652                 }
1653         } else {
1654                 r = policy_lookup(cache->policy, block, &cblock, data_dir, false, &background_queued);
1655                 if (unlikely(r && r != -ENOENT)) {
1656                         DMERR_LIMIT("%s: policy_lookup() failed with r = %d",
1657                                     cache_device_name(cache), r);
1658                         bio_io_error(bio);
1659                         return DM_MAPIO_SUBMITTED;
1660                 }
1661
1662                 if (background_queued)
1663                         wake_migration_worker(cache);
1664         }
1665
1666         if (r == -ENOENT) {
1667                 struct per_bio_data *pb = get_per_bio_data(bio);
1668
1669                 /*
1670                  * Miss.
1671                  */
1672                 inc_miss_counter(cache, bio);
1673                 if (pb->req_nr == 0) {
1674                         accounted_begin(cache, bio);
1675                         remap_to_origin_clear_discard(cache, bio, block);
1676                 } else {
1677                         /*
1678                          * This is a duplicate writethrough io that is no
1679                          * longer needed because the block has been demoted.
1680                          */
1681                         bio_endio(bio);
1682                         return DM_MAPIO_SUBMITTED;
1683                 }
1684         } else {
1685                 /*
1686                  * Hit.
1687                  */
1688                 inc_hit_counter(cache, bio);
1689
1690                 /*
1691                  * Passthrough always maps to the origin, invalidating any
1692                  * cache blocks that are written to.
1693                  */
1694                 if (passthrough_mode(cache)) {
1695                         if (bio_data_dir(bio) == WRITE) {
1696                                 bio_drop_shared_lock(cache, bio);
1697                                 atomic_inc(&cache->stats.demotion);
1698                                 invalidate_start(cache, cblock, block, bio);
1699                         } else
1700                                 remap_to_origin_clear_discard(cache, bio, block);
1701                 } else {
1702                         if (bio_data_dir(bio) == WRITE && writethrough_mode(cache) &&
1703                             !is_dirty(cache, cblock)) {
1704                                 remap_to_origin_and_cache(cache, bio, block, cblock);
1705                                 accounted_begin(cache, bio);
1706                         } else
1707                                 remap_to_cache_dirty(cache, bio, block, cblock);
1708                 }
1709         }
1710
1711         /*
1712          * dm core turns FUA requests into a separate payload and FLUSH req.
1713          */
1714         if (bio->bi_opf & REQ_FUA) {
1715                 /*
1716                  * issue_after_commit will call accounted_begin a second time.  So
1717                  * we call accounted_complete() to avoid double accounting.
1718                  */
1719                 accounted_complete(cache, bio);
1720                 issue_after_commit(&cache->committer, bio);
1721                 *commit_needed = true;
1722                 return DM_MAPIO_SUBMITTED;
1723         }
1724
1725         return DM_MAPIO_REMAPPED;
1726 }
1727
1728 static bool process_bio(struct cache *cache, struct bio *bio)
1729 {
1730         bool commit_needed;
1731
1732         if (map_bio(cache, bio, get_bio_block(cache, bio), &commit_needed) == DM_MAPIO_REMAPPED)
1733                 dm_submit_bio_remap(bio, NULL);
1734
1735         return commit_needed;
1736 }
1737
1738 /*
1739  * A non-zero return indicates read_only or fail_io mode.
1740  */
1741 static int commit(struct cache *cache, bool clean_shutdown)
1742 {
1743         int r;
1744
1745         if (get_cache_mode(cache) >= CM_READ_ONLY)
1746                 return -EINVAL;
1747
1748         atomic_inc(&cache->stats.commit_count);
1749         r = dm_cache_commit(cache->cmd, clean_shutdown);
1750         if (r)
1751                 metadata_operation_failed(cache, "dm_cache_commit", r);
1752
1753         return r;
1754 }
1755
1756 /*
1757  * Used by the batcher.
1758  */
1759 static blk_status_t commit_op(void *context)
1760 {
1761         struct cache *cache = context;
1762
1763         if (dm_cache_changed_this_transaction(cache->cmd))
1764                 return errno_to_blk_status(commit(cache, false));
1765
1766         return 0;
1767 }
1768
1769 /*----------------------------------------------------------------*/
1770
1771 static bool process_flush_bio(struct cache *cache, struct bio *bio)
1772 {
1773         struct per_bio_data *pb = get_per_bio_data(bio);
1774
1775         if (!pb->req_nr)
1776                 remap_to_origin(cache, bio);
1777         else
1778                 remap_to_cache(cache, bio, 0);
1779
1780         issue_after_commit(&cache->committer, bio);
1781         return true;
1782 }
1783
1784 static bool process_discard_bio(struct cache *cache, struct bio *bio)
1785 {
1786         dm_dblock_t b, e;
1787
1788         /*
1789          * FIXME: do we need to lock the region?  Or can we just assume the
1790          * user wont be so foolish as to issue discard concurrently with
1791          * other IO?
1792          */
1793         calc_discard_block_range(cache, bio, &b, &e);
1794         while (b != e) {
1795                 set_discard(cache, b);
1796                 b = to_dblock(from_dblock(b) + 1);
1797         }
1798
1799         if (cache->features.discard_passdown) {
1800                 remap_to_origin(cache, bio);
1801                 dm_submit_bio_remap(bio, NULL);
1802         } else
1803                 bio_endio(bio);
1804
1805         return false;
1806 }
1807
1808 static void process_deferred_bios(struct work_struct *ws)
1809 {
1810         struct cache *cache = container_of(ws, struct cache, deferred_bio_worker);
1811
1812         bool commit_needed = false;
1813         struct bio_list bios;
1814         struct bio *bio;
1815
1816         bio_list_init(&bios);
1817
1818         spin_lock_irq(&cache->lock);
1819         bio_list_merge(&bios, &cache->deferred_bios);
1820         bio_list_init(&cache->deferred_bios);
1821         spin_unlock_irq(&cache->lock);
1822
1823         while ((bio = bio_list_pop(&bios))) {
1824                 if (bio->bi_opf & REQ_PREFLUSH)
1825                         commit_needed = process_flush_bio(cache, bio) || commit_needed;
1826
1827                 else if (bio_op(bio) == REQ_OP_DISCARD)
1828                         commit_needed = process_discard_bio(cache, bio) || commit_needed;
1829
1830                 else
1831                         commit_needed = process_bio(cache, bio) || commit_needed;
1832                 cond_resched();
1833         }
1834
1835         if (commit_needed)
1836                 schedule_commit(&cache->committer);
1837 }
1838
1839 /*
1840  *--------------------------------------------------------------
1841  * Main worker loop
1842  *--------------------------------------------------------------
1843  */
1844 static void requeue_deferred_bios(struct cache *cache)
1845 {
1846         struct bio *bio;
1847         struct bio_list bios;
1848
1849         bio_list_init(&bios);
1850         bio_list_merge(&bios, &cache->deferred_bios);
1851         bio_list_init(&cache->deferred_bios);
1852
1853         while ((bio = bio_list_pop(&bios))) {
1854                 bio->bi_status = BLK_STS_DM_REQUEUE;
1855                 bio_endio(bio);
1856                 cond_resched();
1857         }
1858 }
1859
1860 /*
1861  * We want to commit periodically so that not too much
1862  * unwritten metadata builds up.
1863  */
1864 static void do_waker(struct work_struct *ws)
1865 {
1866         struct cache *cache = container_of(to_delayed_work(ws), struct cache, waker);
1867
1868         policy_tick(cache->policy, true);
1869         wake_migration_worker(cache);
1870         schedule_commit(&cache->committer);
1871         queue_delayed_work(cache->wq, &cache->waker, COMMIT_PERIOD);
1872 }
1873
1874 static void check_migrations(struct work_struct *ws)
1875 {
1876         int r;
1877         struct policy_work *op;
1878         struct cache *cache = container_of(ws, struct cache, migration_worker);
1879         enum busy b;
1880
1881         for (;;) {
1882                 b = spare_migration_bandwidth(cache);
1883
1884                 r = policy_get_background_work(cache->policy, b == IDLE, &op);
1885                 if (r == -ENODATA)
1886                         break;
1887
1888                 if (r) {
1889                         DMERR_LIMIT("%s: policy_background_work failed",
1890                                     cache_device_name(cache));
1891                         break;
1892                 }
1893
1894                 r = mg_start(cache, op, NULL);
1895                 if (r)
1896                         break;
1897
1898                 cond_resched();
1899         }
1900 }
1901
1902 /*
1903  *--------------------------------------------------------------
1904  * Target methods
1905  *--------------------------------------------------------------
1906  */
1907
1908 /*
1909  * This function gets called on the error paths of the constructor, so we
1910  * have to cope with a partially initialised struct.
1911  */
1912 static void destroy(struct cache *cache)
1913 {
1914         unsigned int i;
1915
1916         mempool_exit(&cache->migration_pool);
1917
1918         if (cache->prison)
1919                 dm_bio_prison_destroy_v2(cache->prison);
1920
1921         cancel_delayed_work_sync(&cache->waker);
1922         if (cache->wq)
1923                 destroy_workqueue(cache->wq);
1924
1925         if (cache->dirty_bitset)
1926                 free_bitset(cache->dirty_bitset);
1927
1928         if (cache->discard_bitset)
1929                 free_bitset(cache->discard_bitset);
1930
1931         if (cache->copier)
1932                 dm_kcopyd_client_destroy(cache->copier);
1933
1934         if (cache->cmd)
1935                 dm_cache_metadata_close(cache->cmd);
1936
1937         if (cache->metadata_dev)
1938                 dm_put_device(cache->ti, cache->metadata_dev);
1939
1940         if (cache->origin_dev)
1941                 dm_put_device(cache->ti, cache->origin_dev);
1942
1943         if (cache->cache_dev)
1944                 dm_put_device(cache->ti, cache->cache_dev);
1945
1946         if (cache->policy)
1947                 dm_cache_policy_destroy(cache->policy);
1948
1949         for (i = 0; i < cache->nr_ctr_args ; i++)
1950                 kfree(cache->ctr_args[i]);
1951         kfree(cache->ctr_args);
1952
1953         bioset_exit(&cache->bs);
1954
1955         kfree(cache);
1956 }
1957
1958 static void cache_dtr(struct dm_target *ti)
1959 {
1960         struct cache *cache = ti->private;
1961
1962         destroy(cache);
1963 }
1964
1965 static sector_t get_dev_size(struct dm_dev *dev)
1966 {
1967         return bdev_nr_sectors(dev->bdev);
1968 }
1969
1970 /*----------------------------------------------------------------*/
1971
1972 /*
1973  * Construct a cache device mapping.
1974  *
1975  * cache <metadata dev> <cache dev> <origin dev> <block size>
1976  *       <#feature args> [<feature arg>]*
1977  *       <policy> <#policy args> [<policy arg>]*
1978  *
1979  * metadata dev    : fast device holding the persistent metadata
1980  * cache dev       : fast device holding cached data blocks
1981  * origin dev      : slow device holding original data blocks
1982  * block size      : cache unit size in sectors
1983  *
1984  * #feature args   : number of feature arguments passed
1985  * feature args    : writethrough.  (The default is writeback.)
1986  *
1987  * policy          : the replacement policy to use
1988  * #policy args    : an even number of policy arguments corresponding
1989  *                   to key/value pairs passed to the policy
1990  * policy args     : key/value pairs passed to the policy
1991  *                   E.g. 'sequential_threshold 1024'
1992  *                   See cache-policies.txt for details.
1993  *
1994  * Optional feature arguments are:
1995  *   writethrough  : write through caching that prohibits cache block
1996  *                   content from being different from origin block content.
1997  *                   Without this argument, the default behaviour is to write
1998  *                   back cache block contents later for performance reasons,
1999  *                   so they may differ from the corresponding origin blocks.
2000  */
2001 struct cache_args {
2002         struct dm_target *ti;
2003
2004         struct dm_dev *metadata_dev;
2005
2006         struct dm_dev *cache_dev;
2007         sector_t cache_sectors;
2008
2009         struct dm_dev *origin_dev;
2010         sector_t origin_sectors;
2011
2012         uint32_t block_size;
2013
2014         const char *policy_name;
2015         int policy_argc;
2016         const char **policy_argv;
2017
2018         struct cache_features features;
2019 };
2020
2021 static void destroy_cache_args(struct cache_args *ca)
2022 {
2023         if (ca->metadata_dev)
2024                 dm_put_device(ca->ti, ca->metadata_dev);
2025
2026         if (ca->cache_dev)
2027                 dm_put_device(ca->ti, ca->cache_dev);
2028
2029         if (ca->origin_dev)
2030                 dm_put_device(ca->ti, ca->origin_dev);
2031
2032         kfree(ca);
2033 }
2034
2035 static bool at_least_one_arg(struct dm_arg_set *as, char **error)
2036 {
2037         if (!as->argc) {
2038                 *error = "Insufficient args";
2039                 return false;
2040         }
2041
2042         return true;
2043 }
2044
2045 static int parse_metadata_dev(struct cache_args *ca, struct dm_arg_set *as,
2046                               char **error)
2047 {
2048         int r;
2049         sector_t metadata_dev_size;
2050
2051         if (!at_least_one_arg(as, error))
2052                 return -EINVAL;
2053
2054         r = dm_get_device(ca->ti, dm_shift_arg(as),
2055                           BLK_OPEN_READ | BLK_OPEN_WRITE, &ca->metadata_dev);
2056         if (r) {
2057                 *error = "Error opening metadata device";
2058                 return r;
2059         }
2060
2061         metadata_dev_size = get_dev_size(ca->metadata_dev);
2062         if (metadata_dev_size > DM_CACHE_METADATA_MAX_SECTORS_WARNING)
2063                 DMWARN("Metadata device %pg is larger than %u sectors: excess space will not be used.",
2064                        ca->metadata_dev->bdev, THIN_METADATA_MAX_SECTORS);
2065
2066         return 0;
2067 }
2068
2069 static int parse_cache_dev(struct cache_args *ca, struct dm_arg_set *as,
2070                            char **error)
2071 {
2072         int r;
2073
2074         if (!at_least_one_arg(as, error))
2075                 return -EINVAL;
2076
2077         r = dm_get_device(ca->ti, dm_shift_arg(as),
2078                           BLK_OPEN_READ | BLK_OPEN_WRITE, &ca->cache_dev);
2079         if (r) {
2080                 *error = "Error opening cache device";
2081                 return r;
2082         }
2083         ca->cache_sectors = get_dev_size(ca->cache_dev);
2084
2085         return 0;
2086 }
2087
2088 static int parse_origin_dev(struct cache_args *ca, struct dm_arg_set *as,
2089                             char **error)
2090 {
2091         int r;
2092
2093         if (!at_least_one_arg(as, error))
2094                 return -EINVAL;
2095
2096         r = dm_get_device(ca->ti, dm_shift_arg(as),
2097                           BLK_OPEN_READ | BLK_OPEN_WRITE, &ca->origin_dev);
2098         if (r) {
2099                 *error = "Error opening origin device";
2100                 return r;
2101         }
2102
2103         ca->origin_sectors = get_dev_size(ca->origin_dev);
2104         if (ca->ti->len > ca->origin_sectors) {
2105                 *error = "Device size larger than cached device";
2106                 return -EINVAL;
2107         }
2108
2109         return 0;
2110 }
2111
2112 static int parse_block_size(struct cache_args *ca, struct dm_arg_set *as,
2113                             char **error)
2114 {
2115         unsigned long block_size;
2116
2117         if (!at_least_one_arg(as, error))
2118                 return -EINVAL;
2119
2120         if (kstrtoul(dm_shift_arg(as), 10, &block_size) || !block_size ||
2121             block_size < DATA_DEV_BLOCK_SIZE_MIN_SECTORS ||
2122             block_size > DATA_DEV_BLOCK_SIZE_MAX_SECTORS ||
2123             block_size & (DATA_DEV_BLOCK_SIZE_MIN_SECTORS - 1)) {
2124                 *error = "Invalid data block size";
2125                 return -EINVAL;
2126         }
2127
2128         if (block_size > ca->cache_sectors) {
2129                 *error = "Data block size is larger than the cache device";
2130                 return -EINVAL;
2131         }
2132
2133         ca->block_size = block_size;
2134
2135         return 0;
2136 }
2137
2138 static void init_features(struct cache_features *cf)
2139 {
2140         cf->mode = CM_WRITE;
2141         cf->io_mode = CM_IO_WRITEBACK;
2142         cf->metadata_version = 1;
2143         cf->discard_passdown = true;
2144 }
2145
2146 static int parse_features(struct cache_args *ca, struct dm_arg_set *as,
2147                           char **error)
2148 {
2149         static const struct dm_arg _args[] = {
2150                 {0, 3, "Invalid number of cache feature arguments"},
2151         };
2152
2153         int r, mode_ctr = 0;
2154         unsigned int argc;
2155         const char *arg;
2156         struct cache_features *cf = &ca->features;
2157
2158         init_features(cf);
2159
2160         r = dm_read_arg_group(_args, as, &argc, error);
2161         if (r)
2162                 return -EINVAL;
2163
2164         while (argc--) {
2165                 arg = dm_shift_arg(as);
2166
2167                 if (!strcasecmp(arg, "writeback")) {
2168                         cf->io_mode = CM_IO_WRITEBACK;
2169                         mode_ctr++;
2170                 }
2171
2172                 else if (!strcasecmp(arg, "writethrough")) {
2173                         cf->io_mode = CM_IO_WRITETHROUGH;
2174                         mode_ctr++;
2175                 }
2176
2177                 else if (!strcasecmp(arg, "passthrough")) {
2178                         cf->io_mode = CM_IO_PASSTHROUGH;
2179                         mode_ctr++;
2180                 }
2181
2182                 else if (!strcasecmp(arg, "metadata2"))
2183                         cf->metadata_version = 2;
2184
2185                 else if (!strcasecmp(arg, "no_discard_passdown"))
2186                         cf->discard_passdown = false;
2187
2188                 else {
2189                         *error = "Unrecognised cache feature requested";
2190                         return -EINVAL;
2191                 }
2192         }
2193
2194         if (mode_ctr > 1) {
2195                 *error = "Duplicate cache io_mode features requested";
2196                 return -EINVAL;
2197         }
2198
2199         return 0;
2200 }
2201
2202 static int parse_policy(struct cache_args *ca, struct dm_arg_set *as,
2203                         char **error)
2204 {
2205         static const struct dm_arg _args[] = {
2206                 {0, 1024, "Invalid number of policy arguments"},
2207         };
2208
2209         int r;
2210
2211         if (!at_least_one_arg(as, error))
2212                 return -EINVAL;
2213
2214         ca->policy_name = dm_shift_arg(as);
2215
2216         r = dm_read_arg_group(_args, as, &ca->policy_argc, error);
2217         if (r)
2218                 return -EINVAL;
2219
2220         ca->policy_argv = (const char **)as->argv;
2221         dm_consume_args(as, ca->policy_argc);
2222
2223         return 0;
2224 }
2225
2226 static int parse_cache_args(struct cache_args *ca, int argc, char **argv,
2227                             char **error)
2228 {
2229         int r;
2230         struct dm_arg_set as;
2231
2232         as.argc = argc;
2233         as.argv = argv;
2234
2235         r = parse_metadata_dev(ca, &as, error);
2236         if (r)
2237                 return r;
2238
2239         r = parse_cache_dev(ca, &as, error);
2240         if (r)
2241                 return r;
2242
2243         r = parse_origin_dev(ca, &as, error);
2244         if (r)
2245                 return r;
2246
2247         r = parse_block_size(ca, &as, error);
2248         if (r)
2249                 return r;
2250
2251         r = parse_features(ca, &as, error);
2252         if (r)
2253                 return r;
2254
2255         r = parse_policy(ca, &as, error);
2256         if (r)
2257                 return r;
2258
2259         return 0;
2260 }
2261
2262 /*----------------------------------------------------------------*/
2263
2264 static struct kmem_cache *migration_cache;
2265
2266 #define NOT_CORE_OPTION 1
2267
2268 static int process_config_option(struct cache *cache, const char *key, const char *value)
2269 {
2270         unsigned long tmp;
2271
2272         if (!strcasecmp(key, "migration_threshold")) {
2273                 if (kstrtoul(value, 10, &tmp))
2274                         return -EINVAL;
2275
2276                 cache->migration_threshold = tmp;
2277                 return 0;
2278         }
2279
2280         return NOT_CORE_OPTION;
2281 }
2282
2283 static int set_config_value(struct cache *cache, const char *key, const char *value)
2284 {
2285         int r = process_config_option(cache, key, value);
2286
2287         if (r == NOT_CORE_OPTION)
2288                 r = policy_set_config_value(cache->policy, key, value);
2289
2290         if (r)
2291                 DMWARN("bad config value for %s: %s", key, value);
2292
2293         return r;
2294 }
2295
2296 static int set_config_values(struct cache *cache, int argc, const char **argv)
2297 {
2298         int r = 0;
2299
2300         if (argc & 1) {
2301                 DMWARN("Odd number of policy arguments given but they should be <key> <value> pairs.");
2302                 return -EINVAL;
2303         }
2304
2305         while (argc) {
2306                 r = set_config_value(cache, argv[0], argv[1]);
2307                 if (r)
2308                         break;
2309
2310                 argc -= 2;
2311                 argv += 2;
2312         }
2313
2314         return r;
2315 }
2316
2317 static int create_cache_policy(struct cache *cache, struct cache_args *ca,
2318                                char **error)
2319 {
2320         struct dm_cache_policy *p = dm_cache_policy_create(ca->policy_name,
2321                                                            cache->cache_size,
2322                                                            cache->origin_sectors,
2323                                                            cache->sectors_per_block);
2324         if (IS_ERR(p)) {
2325                 *error = "Error creating cache's policy";
2326                 return PTR_ERR(p);
2327         }
2328         cache->policy = p;
2329         BUG_ON(!cache->policy);
2330
2331         return 0;
2332 }
2333
2334 /*
2335  * We want the discard block size to be at least the size of the cache
2336  * block size and have no more than 2^14 discard blocks across the origin.
2337  */
2338 #define MAX_DISCARD_BLOCKS (1 << 14)
2339
2340 static bool too_many_discard_blocks(sector_t discard_block_size,
2341                                     sector_t origin_size)
2342 {
2343         (void) sector_div(origin_size, discard_block_size);
2344
2345         return origin_size > MAX_DISCARD_BLOCKS;
2346 }
2347
2348 static sector_t calculate_discard_block_size(sector_t cache_block_size,
2349                                              sector_t origin_size)
2350 {
2351         sector_t discard_block_size = cache_block_size;
2352
2353         if (origin_size)
2354                 while (too_many_discard_blocks(discard_block_size, origin_size))
2355                         discard_block_size *= 2;
2356
2357         return discard_block_size;
2358 }
2359
2360 static void set_cache_size(struct cache *cache, dm_cblock_t size)
2361 {
2362         dm_block_t nr_blocks = from_cblock(size);
2363
2364         if (nr_blocks > (1 << 20) && cache->cache_size != size)
2365                 DMWARN_LIMIT("You have created a cache device with a lot of individual cache blocks (%llu)\n"
2366                              "All these mappings can consume a lot of kernel memory, and take some time to read/write.\n"
2367                              "Please consider increasing the cache block size to reduce the overall cache block count.",
2368                              (unsigned long long) nr_blocks);
2369
2370         cache->cache_size = size;
2371 }
2372
2373 #define DEFAULT_MIGRATION_THRESHOLD 2048
2374
2375 static int cache_create(struct cache_args *ca, struct cache **result)
2376 {
2377         int r = 0;
2378         char **error = &ca->ti->error;
2379         struct cache *cache;
2380         struct dm_target *ti = ca->ti;
2381         dm_block_t origin_blocks;
2382         struct dm_cache_metadata *cmd;
2383         bool may_format = ca->features.mode == CM_WRITE;
2384
2385         cache = kzalloc(sizeof(*cache), GFP_KERNEL);
2386         if (!cache)
2387                 return -ENOMEM;
2388
2389         cache->ti = ca->ti;
2390         ti->private = cache;
2391         ti->accounts_remapped_io = true;
2392         ti->num_flush_bios = 2;
2393         ti->flush_supported = true;
2394
2395         ti->num_discard_bios = 1;
2396         ti->discards_supported = true;
2397
2398         ti->per_io_data_size = sizeof(struct per_bio_data);
2399
2400         cache->features = ca->features;
2401         if (writethrough_mode(cache)) {
2402                 /* Create bioset for writethrough bios issued to origin */
2403                 r = bioset_init(&cache->bs, BIO_POOL_SIZE, 0, 0);
2404                 if (r)
2405                         goto bad;
2406         }
2407
2408         cache->metadata_dev = ca->metadata_dev;
2409         cache->origin_dev = ca->origin_dev;
2410         cache->cache_dev = ca->cache_dev;
2411
2412         ca->metadata_dev = ca->origin_dev = ca->cache_dev = NULL;
2413
2414         origin_blocks = cache->origin_sectors = ca->origin_sectors;
2415         origin_blocks = block_div(origin_blocks, ca->block_size);
2416         cache->origin_blocks = to_oblock(origin_blocks);
2417
2418         cache->sectors_per_block = ca->block_size;
2419         if (dm_set_target_max_io_len(ti, cache->sectors_per_block)) {
2420                 r = -EINVAL;
2421                 goto bad;
2422         }
2423
2424         if (ca->block_size & (ca->block_size - 1)) {
2425                 dm_block_t cache_size = ca->cache_sectors;
2426
2427                 cache->sectors_per_block_shift = -1;
2428                 cache_size = block_div(cache_size, ca->block_size);
2429                 set_cache_size(cache, to_cblock(cache_size));
2430         } else {
2431                 cache->sectors_per_block_shift = __ffs(ca->block_size);
2432                 set_cache_size(cache, to_cblock(ca->cache_sectors >> cache->sectors_per_block_shift));
2433         }
2434
2435         r = create_cache_policy(cache, ca, error);
2436         if (r)
2437                 goto bad;
2438
2439         cache->policy_nr_args = ca->policy_argc;
2440         cache->migration_threshold = DEFAULT_MIGRATION_THRESHOLD;
2441
2442         r = set_config_values(cache, ca->policy_argc, ca->policy_argv);
2443         if (r) {
2444                 *error = "Error setting cache policy's config values";
2445                 goto bad;
2446         }
2447
2448         cmd = dm_cache_metadata_open(cache->metadata_dev->bdev,
2449                                      ca->block_size, may_format,
2450                                      dm_cache_policy_get_hint_size(cache->policy),
2451                                      ca->features.metadata_version);
2452         if (IS_ERR(cmd)) {
2453                 *error = "Error creating metadata object";
2454                 r = PTR_ERR(cmd);
2455                 goto bad;
2456         }
2457         cache->cmd = cmd;
2458         set_cache_mode(cache, CM_WRITE);
2459         if (get_cache_mode(cache) != CM_WRITE) {
2460                 *error = "Unable to get write access to metadata, please check/repair metadata.";
2461                 r = -EINVAL;
2462                 goto bad;
2463         }
2464
2465         if (passthrough_mode(cache)) {
2466                 bool all_clean;
2467
2468                 r = dm_cache_metadata_all_clean(cache->cmd, &all_clean);
2469                 if (r) {
2470                         *error = "dm_cache_metadata_all_clean() failed";
2471                         goto bad;
2472                 }
2473
2474                 if (!all_clean) {
2475                         *error = "Cannot enter passthrough mode unless all blocks are clean";
2476                         r = -EINVAL;
2477                         goto bad;
2478                 }
2479
2480                 policy_allow_migrations(cache->policy, false);
2481         }
2482
2483         spin_lock_init(&cache->lock);
2484         bio_list_init(&cache->deferred_bios);
2485         atomic_set(&cache->nr_allocated_migrations, 0);
2486         atomic_set(&cache->nr_io_migrations, 0);
2487         init_waitqueue_head(&cache->migration_wait);
2488
2489         r = -ENOMEM;
2490         atomic_set(&cache->nr_dirty, 0);
2491         cache->dirty_bitset = alloc_bitset(from_cblock(cache->cache_size));
2492         if (!cache->dirty_bitset) {
2493                 *error = "could not allocate dirty bitset";
2494                 goto bad;
2495         }
2496         clear_bitset(cache->dirty_bitset, from_cblock(cache->cache_size));
2497
2498         cache->discard_block_size =
2499                 calculate_discard_block_size(cache->sectors_per_block,
2500                                              cache->origin_sectors);
2501         cache->discard_nr_blocks = to_dblock(dm_sector_div_up(cache->origin_sectors,
2502                                                               cache->discard_block_size));
2503         cache->discard_bitset = alloc_bitset(from_dblock(cache->discard_nr_blocks));
2504         if (!cache->discard_bitset) {
2505                 *error = "could not allocate discard bitset";
2506                 goto bad;
2507         }
2508         clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks));
2509
2510         cache->copier = dm_kcopyd_client_create(&dm_kcopyd_throttle);
2511         if (IS_ERR(cache->copier)) {
2512                 *error = "could not create kcopyd client";
2513                 r = PTR_ERR(cache->copier);
2514                 goto bad;
2515         }
2516
2517         cache->wq = alloc_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM, 0);
2518         if (!cache->wq) {
2519                 *error = "could not create workqueue for metadata object";
2520                 goto bad;
2521         }
2522         INIT_WORK(&cache->deferred_bio_worker, process_deferred_bios);
2523         INIT_WORK(&cache->migration_worker, check_migrations);
2524         INIT_DELAYED_WORK(&cache->waker, do_waker);
2525
2526         cache->prison = dm_bio_prison_create_v2(cache->wq);
2527         if (!cache->prison) {
2528                 *error = "could not create bio prison";
2529                 goto bad;
2530         }
2531
2532         r = mempool_init_slab_pool(&cache->migration_pool, MIGRATION_POOL_SIZE,
2533                                    migration_cache);
2534         if (r) {
2535                 *error = "Error creating cache's migration mempool";
2536                 goto bad;
2537         }
2538
2539         cache->need_tick_bio = true;
2540         cache->sized = false;
2541         cache->invalidate = false;
2542         cache->commit_requested = false;
2543         cache->loaded_mappings = false;
2544         cache->loaded_discards = false;
2545
2546         load_stats(cache);
2547
2548         atomic_set(&cache->stats.demotion, 0);
2549         atomic_set(&cache->stats.promotion, 0);
2550         atomic_set(&cache->stats.copies_avoided, 0);
2551         atomic_set(&cache->stats.cache_cell_clash, 0);
2552         atomic_set(&cache->stats.commit_count, 0);
2553         atomic_set(&cache->stats.discard_count, 0);
2554
2555         spin_lock_init(&cache->invalidation_lock);
2556         INIT_LIST_HEAD(&cache->invalidation_requests);
2557
2558         batcher_init(&cache->committer, commit_op, cache,
2559                      issue_op, cache, cache->wq);
2560         dm_iot_init(&cache->tracker);
2561
2562         init_rwsem(&cache->background_work_lock);
2563         prevent_background_work(cache);
2564
2565         *result = cache;
2566         return 0;
2567 bad:
2568         destroy(cache);
2569         return r;
2570 }
2571
2572 static int copy_ctr_args(struct cache *cache, int argc, const char **argv)
2573 {
2574         unsigned int i;
2575         const char **copy;
2576
2577         copy = kcalloc(argc, sizeof(*copy), GFP_KERNEL);
2578         if (!copy)
2579                 return -ENOMEM;
2580         for (i = 0; i < argc; i++) {
2581                 copy[i] = kstrdup(argv[i], GFP_KERNEL);
2582                 if (!copy[i]) {
2583                         while (i--)
2584                                 kfree(copy[i]);
2585                         kfree(copy);
2586                         return -ENOMEM;
2587                 }
2588         }
2589
2590         cache->nr_ctr_args = argc;
2591         cache->ctr_args = copy;
2592
2593         return 0;
2594 }
2595
2596 static int cache_ctr(struct dm_target *ti, unsigned int argc, char **argv)
2597 {
2598         int r = -EINVAL;
2599         struct cache_args *ca;
2600         struct cache *cache = NULL;
2601
2602         ca = kzalloc(sizeof(*ca), GFP_KERNEL);
2603         if (!ca) {
2604                 ti->error = "Error allocating memory for cache";
2605                 return -ENOMEM;
2606         }
2607         ca->ti = ti;
2608
2609         r = parse_cache_args(ca, argc, argv, &ti->error);
2610         if (r)
2611                 goto out;
2612
2613         r = cache_create(ca, &cache);
2614         if (r)
2615                 goto out;
2616
2617         r = copy_ctr_args(cache, argc - 3, (const char **)argv + 3);
2618         if (r) {
2619                 destroy(cache);
2620                 goto out;
2621         }
2622
2623         ti->private = cache;
2624 out:
2625         destroy_cache_args(ca);
2626         return r;
2627 }
2628
2629 /*----------------------------------------------------------------*/
2630
2631 static int cache_map(struct dm_target *ti, struct bio *bio)
2632 {
2633         struct cache *cache = ti->private;
2634
2635         int r;
2636         bool commit_needed;
2637         dm_oblock_t block = get_bio_block(cache, bio);
2638
2639         init_per_bio_data(bio);
2640         if (unlikely(from_oblock(block) >= from_oblock(cache->origin_blocks))) {
2641                 /*
2642                  * This can only occur if the io goes to a partial block at
2643                  * the end of the origin device.  We don't cache these.
2644                  * Just remap to the origin and carry on.
2645                  */
2646                 remap_to_origin(cache, bio);
2647                 accounted_begin(cache, bio);
2648                 return DM_MAPIO_REMAPPED;
2649         }
2650
2651         if (discard_or_flush(bio)) {
2652                 defer_bio(cache, bio);
2653                 return DM_MAPIO_SUBMITTED;
2654         }
2655
2656         r = map_bio(cache, bio, block, &commit_needed);
2657         if (commit_needed)
2658                 schedule_commit(&cache->committer);
2659
2660         return r;
2661 }
2662
2663 static int cache_end_io(struct dm_target *ti, struct bio *bio, blk_status_t *error)
2664 {
2665         struct cache *cache = ti->private;
2666         unsigned long flags;
2667         struct per_bio_data *pb = get_per_bio_data(bio);
2668
2669         if (pb->tick) {
2670                 policy_tick(cache->policy, false);
2671
2672                 spin_lock_irqsave(&cache->lock, flags);
2673                 cache->need_tick_bio = true;
2674                 spin_unlock_irqrestore(&cache->lock, flags);
2675         }
2676
2677         bio_drop_shared_lock(cache, bio);
2678         accounted_complete(cache, bio);
2679
2680         return DM_ENDIO_DONE;
2681 }
2682
2683 static int write_dirty_bitset(struct cache *cache)
2684 {
2685         int r;
2686
2687         if (get_cache_mode(cache) >= CM_READ_ONLY)
2688                 return -EINVAL;
2689
2690         r = dm_cache_set_dirty_bits(cache->cmd, from_cblock(cache->cache_size), cache->dirty_bitset);
2691         if (r)
2692                 metadata_operation_failed(cache, "dm_cache_set_dirty_bits", r);
2693
2694         return r;
2695 }
2696
2697 static int write_discard_bitset(struct cache *cache)
2698 {
2699         unsigned int i, r;
2700
2701         if (get_cache_mode(cache) >= CM_READ_ONLY)
2702                 return -EINVAL;
2703
2704         r = dm_cache_discard_bitset_resize(cache->cmd, cache->discard_block_size,
2705                                            cache->discard_nr_blocks);
2706         if (r) {
2707                 DMERR("%s: could not resize on-disk discard bitset", cache_device_name(cache));
2708                 metadata_operation_failed(cache, "dm_cache_discard_bitset_resize", r);
2709                 return r;
2710         }
2711
2712         for (i = 0; i < from_dblock(cache->discard_nr_blocks); i++) {
2713                 r = dm_cache_set_discard(cache->cmd, to_dblock(i),
2714                                          is_discarded(cache, to_dblock(i)));
2715                 if (r) {
2716                         metadata_operation_failed(cache, "dm_cache_set_discard", r);
2717                         return r;
2718                 }
2719         }
2720
2721         return 0;
2722 }
2723
2724 static int write_hints(struct cache *cache)
2725 {
2726         int r;
2727
2728         if (get_cache_mode(cache) >= CM_READ_ONLY)
2729                 return -EINVAL;
2730
2731         r = dm_cache_write_hints(cache->cmd, cache->policy);
2732         if (r) {
2733                 metadata_operation_failed(cache, "dm_cache_write_hints", r);
2734                 return r;
2735         }
2736
2737         return 0;
2738 }
2739
2740 /*
2741  * returns true on success
2742  */
2743 static bool sync_metadata(struct cache *cache)
2744 {
2745         int r1, r2, r3, r4;
2746
2747         r1 = write_dirty_bitset(cache);
2748         if (r1)
2749                 DMERR("%s: could not write dirty bitset", cache_device_name(cache));
2750
2751         r2 = write_discard_bitset(cache);
2752         if (r2)
2753                 DMERR("%s: could not write discard bitset", cache_device_name(cache));
2754
2755         save_stats(cache);
2756
2757         r3 = write_hints(cache);
2758         if (r3)
2759                 DMERR("%s: could not write hints", cache_device_name(cache));
2760
2761         /*
2762          * If writing the above metadata failed, we still commit, but don't
2763          * set the clean shutdown flag.  This will effectively force every
2764          * dirty bit to be set on reload.
2765          */
2766         r4 = commit(cache, !r1 && !r2 && !r3);
2767         if (r4)
2768                 DMERR("%s: could not write cache metadata", cache_device_name(cache));
2769
2770         return !r1 && !r2 && !r3 && !r4;
2771 }
2772
2773 static void cache_postsuspend(struct dm_target *ti)
2774 {
2775         struct cache *cache = ti->private;
2776
2777         prevent_background_work(cache);
2778         BUG_ON(atomic_read(&cache->nr_io_migrations));
2779
2780         cancel_delayed_work_sync(&cache->waker);
2781         drain_workqueue(cache->wq);
2782         WARN_ON(cache->tracker.in_flight);
2783
2784         /*
2785          * If it's a flush suspend there won't be any deferred bios, so this
2786          * call is harmless.
2787          */
2788         requeue_deferred_bios(cache);
2789
2790         if (get_cache_mode(cache) == CM_WRITE)
2791                 (void) sync_metadata(cache);
2792 }
2793
2794 static int load_mapping(void *context, dm_oblock_t oblock, dm_cblock_t cblock,
2795                         bool dirty, uint32_t hint, bool hint_valid)
2796 {
2797         struct cache *cache = context;
2798
2799         if (dirty) {
2800                 set_bit(from_cblock(cblock), cache->dirty_bitset);
2801                 atomic_inc(&cache->nr_dirty);
2802         } else
2803                 clear_bit(from_cblock(cblock), cache->dirty_bitset);
2804
2805         return policy_load_mapping(cache->policy, oblock, cblock, dirty, hint, hint_valid);
2806 }
2807
2808 /*
2809  * The discard block size in the on disk metadata is not
2810  * necessarily the same as we're currently using.  So we have to
2811  * be careful to only set the discarded attribute if we know it
2812  * covers a complete block of the new size.
2813  */
2814 struct discard_load_info {
2815         struct cache *cache;
2816
2817         /*
2818          * These blocks are sized using the on disk dblock size, rather
2819          * than the current one.
2820          */
2821         dm_block_t block_size;
2822         dm_block_t discard_begin, discard_end;
2823 };
2824
2825 static void discard_load_info_init(struct cache *cache,
2826                                    struct discard_load_info *li)
2827 {
2828         li->cache = cache;
2829         li->discard_begin = li->discard_end = 0;
2830 }
2831
2832 static void set_discard_range(struct discard_load_info *li)
2833 {
2834         sector_t b, e;
2835
2836         if (li->discard_begin == li->discard_end)
2837                 return;
2838
2839         /*
2840          * Convert to sectors.
2841          */
2842         b = li->discard_begin * li->block_size;
2843         e = li->discard_end * li->block_size;
2844
2845         /*
2846          * Then convert back to the current dblock size.
2847          */
2848         b = dm_sector_div_up(b, li->cache->discard_block_size);
2849         sector_div(e, li->cache->discard_block_size);
2850
2851         /*
2852          * The origin may have shrunk, so we need to check we're still in
2853          * bounds.
2854          */
2855         if (e > from_dblock(li->cache->discard_nr_blocks))
2856                 e = from_dblock(li->cache->discard_nr_blocks);
2857
2858         for (; b < e; b++)
2859                 set_discard(li->cache, to_dblock(b));
2860 }
2861
2862 static int load_discard(void *context, sector_t discard_block_size,
2863                         dm_dblock_t dblock, bool discard)
2864 {
2865         struct discard_load_info *li = context;
2866
2867         li->block_size = discard_block_size;
2868
2869         if (discard) {
2870                 if (from_dblock(dblock) == li->discard_end)
2871                         /*
2872                          * We're already in a discard range, just extend it.
2873                          */
2874                         li->discard_end = li->discard_end + 1ULL;
2875
2876                 else {
2877                         /*
2878                          * Emit the old range and start a new one.
2879                          */
2880                         set_discard_range(li);
2881                         li->discard_begin = from_dblock(dblock);
2882                         li->discard_end = li->discard_begin + 1ULL;
2883                 }
2884         } else {
2885                 set_discard_range(li);
2886                 li->discard_begin = li->discard_end = 0;
2887         }
2888
2889         return 0;
2890 }
2891
2892 static dm_cblock_t get_cache_dev_size(struct cache *cache)
2893 {
2894         sector_t size = get_dev_size(cache->cache_dev);
2895         (void) sector_div(size, cache->sectors_per_block);
2896         return to_cblock(size);
2897 }
2898
2899 static bool can_resize(struct cache *cache, dm_cblock_t new_size)
2900 {
2901         if (from_cblock(new_size) > from_cblock(cache->cache_size)) {
2902                 if (cache->sized) {
2903                         DMERR("%s: unable to extend cache due to missing cache table reload",
2904                               cache_device_name(cache));
2905                         return false;
2906                 }
2907         }
2908
2909         /*
2910          * We can't drop a dirty block when shrinking the cache.
2911          */
2912         while (from_cblock(new_size) < from_cblock(cache->cache_size)) {
2913                 new_size = to_cblock(from_cblock(new_size) + 1);
2914                 if (is_dirty(cache, new_size)) {
2915                         DMERR("%s: unable to shrink cache; cache block %llu is dirty",
2916                               cache_device_name(cache),
2917                               (unsigned long long) from_cblock(new_size));
2918                         return false;
2919                 }
2920         }
2921
2922         return true;
2923 }
2924
2925 static int resize_cache_dev(struct cache *cache, dm_cblock_t new_size)
2926 {
2927         int r;
2928
2929         r = dm_cache_resize(cache->cmd, new_size);
2930         if (r) {
2931                 DMERR("%s: could not resize cache metadata", cache_device_name(cache));
2932                 metadata_operation_failed(cache, "dm_cache_resize", r);
2933                 return r;
2934         }
2935
2936         set_cache_size(cache, new_size);
2937
2938         return 0;
2939 }
2940
2941 static int cache_preresume(struct dm_target *ti)
2942 {
2943         int r = 0;
2944         struct cache *cache = ti->private;
2945         dm_cblock_t csize = get_cache_dev_size(cache);
2946
2947         /*
2948          * Check to see if the cache has resized.
2949          */
2950         if (!cache->sized) {
2951                 r = resize_cache_dev(cache, csize);
2952                 if (r)
2953                         return r;
2954
2955                 cache->sized = true;
2956
2957         } else if (csize != cache->cache_size) {
2958                 if (!can_resize(cache, csize))
2959                         return -EINVAL;
2960
2961                 r = resize_cache_dev(cache, csize);
2962                 if (r)
2963                         return r;
2964         }
2965
2966         if (!cache->loaded_mappings) {
2967                 r = dm_cache_load_mappings(cache->cmd, cache->policy,
2968                                            load_mapping, cache);
2969                 if (r) {
2970                         DMERR("%s: could not load cache mappings", cache_device_name(cache));
2971                         metadata_operation_failed(cache, "dm_cache_load_mappings", r);
2972                         return r;
2973                 }
2974
2975                 cache->loaded_mappings = true;
2976         }
2977
2978         if (!cache->loaded_discards) {
2979                 struct discard_load_info li;
2980
2981                 /*
2982                  * The discard bitset could have been resized, or the
2983                  * discard block size changed.  To be safe we start by
2984                  * setting every dblock to not discarded.
2985                  */
2986                 clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks));
2987
2988                 discard_load_info_init(cache, &li);
2989                 r = dm_cache_load_discards(cache->cmd, load_discard, &li);
2990                 if (r) {
2991                         DMERR("%s: could not load origin discards", cache_device_name(cache));
2992                         metadata_operation_failed(cache, "dm_cache_load_discards", r);
2993                         return r;
2994                 }
2995                 set_discard_range(&li);
2996
2997                 cache->loaded_discards = true;
2998         }
2999
3000         return r;
3001 }
3002
3003 static void cache_resume(struct dm_target *ti)
3004 {
3005         struct cache *cache = ti->private;
3006
3007         cache->need_tick_bio = true;
3008         allow_background_work(cache);
3009         do_waker(&cache->waker.work);
3010 }
3011
3012 static void emit_flags(struct cache *cache, char *result,
3013                        unsigned int maxlen, ssize_t *sz_ptr)
3014 {
3015         ssize_t sz = *sz_ptr;
3016         struct cache_features *cf = &cache->features;
3017         unsigned int count = (cf->metadata_version == 2) + !cf->discard_passdown + 1;
3018
3019         DMEMIT("%u ", count);
3020
3021         if (cf->metadata_version == 2)
3022                 DMEMIT("metadata2 ");
3023
3024         if (writethrough_mode(cache))
3025                 DMEMIT("writethrough ");
3026
3027         else if (passthrough_mode(cache))
3028                 DMEMIT("passthrough ");
3029
3030         else if (writeback_mode(cache))
3031                 DMEMIT("writeback ");
3032
3033         else {
3034                 DMEMIT("unknown ");
3035                 DMERR("%s: internal error: unknown io mode: %d",
3036                       cache_device_name(cache), (int) cf->io_mode);
3037         }
3038
3039         if (!cf->discard_passdown)
3040                 DMEMIT("no_discard_passdown ");
3041
3042         *sz_ptr = sz;
3043 }
3044
3045 /*
3046  * Status format:
3047  *
3048  * <metadata block size> <#used metadata blocks>/<#total metadata blocks>
3049  * <cache block size> <#used cache blocks>/<#total cache blocks>
3050  * <#read hits> <#read misses> <#write hits> <#write misses>
3051  * <#demotions> <#promotions> <#dirty>
3052  * <#features> <features>*
3053  * <#core args> <core args>
3054  * <policy name> <#policy args> <policy args>* <cache metadata mode> <needs_check>
3055  */
3056 static void cache_status(struct dm_target *ti, status_type_t type,
3057                          unsigned int status_flags, char *result, unsigned int maxlen)
3058 {
3059         int r = 0;
3060         unsigned int i;
3061         ssize_t sz = 0;
3062         dm_block_t nr_free_blocks_metadata = 0;
3063         dm_block_t nr_blocks_metadata = 0;
3064         char buf[BDEVNAME_SIZE];
3065         struct cache *cache = ti->private;
3066         dm_cblock_t residency;
3067         bool needs_check;
3068
3069         switch (type) {
3070         case STATUSTYPE_INFO:
3071                 if (get_cache_mode(cache) == CM_FAIL) {
3072                         DMEMIT("Fail");
3073                         break;
3074                 }
3075
3076                 /* Commit to ensure statistics aren't out-of-date */
3077                 if (!(status_flags & DM_STATUS_NOFLUSH_FLAG) && !dm_suspended(ti))
3078                         (void) commit(cache, false);
3079
3080                 r = dm_cache_get_free_metadata_block_count(cache->cmd, &nr_free_blocks_metadata);
3081                 if (r) {
3082                         DMERR("%s: dm_cache_get_free_metadata_block_count returned %d",
3083                               cache_device_name(cache), r);
3084                         goto err;
3085                 }
3086
3087                 r = dm_cache_get_metadata_dev_size(cache->cmd, &nr_blocks_metadata);
3088                 if (r) {
3089                         DMERR("%s: dm_cache_get_metadata_dev_size returned %d",
3090                               cache_device_name(cache), r);
3091                         goto err;
3092                 }
3093
3094                 residency = policy_residency(cache->policy);
3095
3096                 DMEMIT("%u %llu/%llu %llu %llu/%llu %u %u %u %u %u %u %lu ",
3097                        (unsigned int)DM_CACHE_METADATA_BLOCK_SIZE,
3098                        (unsigned long long)(nr_blocks_metadata - nr_free_blocks_metadata),
3099                        (unsigned long long)nr_blocks_metadata,
3100                        (unsigned long long)cache->sectors_per_block,
3101                        (unsigned long long) from_cblock(residency),
3102                        (unsigned long long) from_cblock(cache->cache_size),
3103                        (unsigned int) atomic_read(&cache->stats.read_hit),
3104                        (unsigned int) atomic_read(&cache->stats.read_miss),
3105                        (unsigned int) atomic_read(&cache->stats.write_hit),
3106                        (unsigned int) atomic_read(&cache->stats.write_miss),
3107                        (unsigned int) atomic_read(&cache->stats.demotion),
3108                        (unsigned int) atomic_read(&cache->stats.promotion),
3109                        (unsigned long) atomic_read(&cache->nr_dirty));
3110
3111                 emit_flags(cache, result, maxlen, &sz);
3112
3113                 DMEMIT("2 migration_threshold %llu ", (unsigned long long) cache->migration_threshold);
3114
3115                 DMEMIT("%s ", dm_cache_policy_get_name(cache->policy));
3116                 if (sz < maxlen) {
3117                         r = policy_emit_config_values(cache->policy, result, maxlen, &sz);
3118                         if (r)
3119                                 DMERR("%s: policy_emit_config_values returned %d",
3120                                       cache_device_name(cache), r);
3121                 }
3122
3123                 if (get_cache_mode(cache) == CM_READ_ONLY)
3124                         DMEMIT("ro ");
3125                 else
3126                         DMEMIT("rw ");
3127
3128                 r = dm_cache_metadata_needs_check(cache->cmd, &needs_check);
3129
3130                 if (r || needs_check)
3131                         DMEMIT("needs_check ");
3132                 else
3133                         DMEMIT("- ");
3134
3135                 break;
3136
3137         case STATUSTYPE_TABLE:
3138                 format_dev_t(buf, cache->metadata_dev->bdev->bd_dev);
3139                 DMEMIT("%s ", buf);
3140                 format_dev_t(buf, cache->cache_dev->bdev->bd_dev);
3141                 DMEMIT("%s ", buf);
3142                 format_dev_t(buf, cache->origin_dev->bdev->bd_dev);
3143                 DMEMIT("%s", buf);
3144
3145                 for (i = 0; i < cache->nr_ctr_args - 1; i++)
3146                         DMEMIT(" %s", cache->ctr_args[i]);
3147                 if (cache->nr_ctr_args)
3148                         DMEMIT(" %s", cache->ctr_args[cache->nr_ctr_args - 1]);
3149                 break;
3150
3151         case STATUSTYPE_IMA:
3152                 DMEMIT_TARGET_NAME_VERSION(ti->type);
3153                 if (get_cache_mode(cache) == CM_FAIL)
3154                         DMEMIT(",metadata_mode=fail");
3155                 else if (get_cache_mode(cache) == CM_READ_ONLY)
3156                         DMEMIT(",metadata_mode=ro");
3157                 else
3158                         DMEMIT(",metadata_mode=rw");
3159
3160                 format_dev_t(buf, cache->metadata_dev->bdev->bd_dev);
3161                 DMEMIT(",cache_metadata_device=%s", buf);
3162                 format_dev_t(buf, cache->cache_dev->bdev->bd_dev);
3163                 DMEMIT(",cache_device=%s", buf);
3164                 format_dev_t(buf, cache->origin_dev->bdev->bd_dev);
3165                 DMEMIT(",cache_origin_device=%s", buf);
3166                 DMEMIT(",writethrough=%c", writethrough_mode(cache) ? 'y' : 'n');
3167                 DMEMIT(",writeback=%c", writeback_mode(cache) ? 'y' : 'n');
3168                 DMEMIT(",passthrough=%c", passthrough_mode(cache) ? 'y' : 'n');
3169                 DMEMIT(",metadata2=%c", cache->features.metadata_version == 2 ? 'y' : 'n');
3170                 DMEMIT(",no_discard_passdown=%c", cache->features.discard_passdown ? 'n' : 'y');
3171                 DMEMIT(";");
3172                 break;
3173         }
3174
3175         return;
3176
3177 err:
3178         DMEMIT("Error");
3179 }
3180
3181 /*
3182  * Defines a range of cblocks, begin to (end - 1) are in the range.  end is
3183  * the one-past-the-end value.
3184  */
3185 struct cblock_range {
3186         dm_cblock_t begin;
3187         dm_cblock_t end;
3188 };
3189
3190 /*
3191  * A cache block range can take two forms:
3192  *
3193  * i) A single cblock, eg. '3456'
3194  * ii) A begin and end cblock with a dash between, eg. 123-234
3195  */
3196 static int parse_cblock_range(struct cache *cache, const char *str,
3197                               struct cblock_range *result)
3198 {
3199         char dummy;
3200         uint64_t b, e;
3201         int r;
3202
3203         /*
3204          * Try and parse form (ii) first.
3205          */
3206         r = sscanf(str, "%llu-%llu%c", &b, &e, &dummy);
3207         if (r < 0)
3208                 return r;
3209
3210         if (r == 2) {
3211                 result->begin = to_cblock(b);
3212                 result->end = to_cblock(e);
3213                 return 0;
3214         }
3215
3216         /*
3217          * That didn't work, try form (i).
3218          */
3219         r = sscanf(str, "%llu%c", &b, &dummy);
3220         if (r < 0)
3221                 return r;
3222
3223         if (r == 1) {
3224                 result->begin = to_cblock(b);
3225                 result->end = to_cblock(from_cblock(result->begin) + 1u);
3226                 return 0;
3227         }
3228
3229         DMERR("%s: invalid cblock range '%s'", cache_device_name(cache), str);
3230         return -EINVAL;
3231 }
3232
3233 static int validate_cblock_range(struct cache *cache, struct cblock_range *range)
3234 {
3235         uint64_t b = from_cblock(range->begin);
3236         uint64_t e = from_cblock(range->end);
3237         uint64_t n = from_cblock(cache->cache_size);
3238
3239         if (b >= n) {
3240                 DMERR("%s: begin cblock out of range: %llu >= %llu",
3241                       cache_device_name(cache), b, n);
3242                 return -EINVAL;
3243         }
3244
3245         if (e > n) {
3246                 DMERR("%s: end cblock out of range: %llu > %llu",
3247                       cache_device_name(cache), e, n);
3248                 return -EINVAL;
3249         }
3250
3251         if (b >= e) {
3252                 DMERR("%s: invalid cblock range: %llu >= %llu",
3253                       cache_device_name(cache), b, e);
3254                 return -EINVAL;
3255         }
3256
3257         return 0;
3258 }
3259
3260 static inline dm_cblock_t cblock_succ(dm_cblock_t b)
3261 {
3262         return to_cblock(from_cblock(b) + 1);
3263 }
3264
3265 static int request_invalidation(struct cache *cache, struct cblock_range *range)
3266 {
3267         int r = 0;
3268
3269         /*
3270          * We don't need to do any locking here because we know we're in
3271          * passthrough mode.  There's is potential for a race between an
3272          * invalidation triggered by an io and an invalidation message.  This
3273          * is harmless, we must not worry if the policy call fails.
3274          */
3275         while (range->begin != range->end) {
3276                 r = invalidate_cblock(cache, range->begin);
3277                 if (r)
3278                         return r;
3279
3280                 range->begin = cblock_succ(range->begin);
3281         }
3282
3283         cache->commit_requested = true;
3284         return r;
3285 }
3286
3287 static int process_invalidate_cblocks_message(struct cache *cache, unsigned int count,
3288                                               const char **cblock_ranges)
3289 {
3290         int r = 0;
3291         unsigned int i;
3292         struct cblock_range range;
3293
3294         if (!passthrough_mode(cache)) {
3295                 DMERR("%s: cache has to be in passthrough mode for invalidation",
3296                       cache_device_name(cache));
3297                 return -EPERM;
3298         }
3299
3300         for (i = 0; i < count; i++) {
3301                 r = parse_cblock_range(cache, cblock_ranges[i], &range);
3302                 if (r)
3303                         break;
3304
3305                 r = validate_cblock_range(cache, &range);
3306                 if (r)
3307                         break;
3308
3309                 /*
3310                  * Pass begin and end origin blocks to the worker and wake it.
3311                  */
3312                 r = request_invalidation(cache, &range);
3313                 if (r)
3314                         break;
3315         }
3316
3317         return r;
3318 }
3319
3320 /*
3321  * Supports
3322  *      "<key> <value>"
3323  * and
3324  *     "invalidate_cblocks [(<begin>)|(<begin>-<end>)]*
3325  *
3326  * The key migration_threshold is supported by the cache target core.
3327  */
3328 static int cache_message(struct dm_target *ti, unsigned int argc, char **argv,
3329                          char *result, unsigned int maxlen)
3330 {
3331         struct cache *cache = ti->private;
3332
3333         if (!argc)
3334                 return -EINVAL;
3335
3336         if (get_cache_mode(cache) >= CM_READ_ONLY) {
3337                 DMERR("%s: unable to service cache target messages in READ_ONLY or FAIL mode",
3338                       cache_device_name(cache));
3339                 return -EOPNOTSUPP;
3340         }
3341
3342         if (!strcasecmp(argv[0], "invalidate_cblocks"))
3343                 return process_invalidate_cblocks_message(cache, argc - 1, (const char **) argv + 1);
3344
3345         if (argc != 2)
3346                 return -EINVAL;
3347
3348         return set_config_value(cache, argv[0], argv[1]);
3349 }
3350
3351 static int cache_iterate_devices(struct dm_target *ti,
3352                                  iterate_devices_callout_fn fn, void *data)
3353 {
3354         int r = 0;
3355         struct cache *cache = ti->private;
3356
3357         r = fn(ti, cache->cache_dev, 0, get_dev_size(cache->cache_dev), data);
3358         if (!r)
3359                 r = fn(ti, cache->origin_dev, 0, ti->len, data);
3360
3361         return r;
3362 }
3363
3364 /*
3365  * If discard_passdown was enabled verify that the origin device
3366  * supports discards.  Disable discard_passdown if not.
3367  */
3368 static void disable_passdown_if_not_supported(struct cache *cache)
3369 {
3370         struct block_device *origin_bdev = cache->origin_dev->bdev;
3371         struct queue_limits *origin_limits = &bdev_get_queue(origin_bdev)->limits;
3372         const char *reason = NULL;
3373
3374         if (!cache->features.discard_passdown)
3375                 return;
3376
3377         if (!bdev_max_discard_sectors(origin_bdev))
3378                 reason = "discard unsupported";
3379
3380         else if (origin_limits->max_discard_sectors < cache->sectors_per_block)
3381                 reason = "max discard sectors smaller than a block";
3382
3383         if (reason) {
3384                 DMWARN("Origin device (%pg) %s: Disabling discard passdown.",
3385                        origin_bdev, reason);
3386                 cache->features.discard_passdown = false;
3387         }
3388 }
3389
3390 static void set_discard_limits(struct cache *cache, struct queue_limits *limits)
3391 {
3392         struct block_device *origin_bdev = cache->origin_dev->bdev;
3393         struct queue_limits *origin_limits = &bdev_get_queue(origin_bdev)->limits;
3394
3395         if (!cache->features.discard_passdown) {
3396                 /* No passdown is done so setting own virtual limits */
3397                 limits->max_discard_sectors = min_t(sector_t, cache->discard_block_size * 1024,
3398                                                     cache->origin_sectors);
3399                 limits->discard_granularity = cache->discard_block_size << SECTOR_SHIFT;
3400                 return;
3401         }
3402
3403         /*
3404          * cache_iterate_devices() is stacking both origin and fast device limits
3405          * but discards aren't passed to fast device, so inherit origin's limits.
3406          */
3407         limits->max_discard_sectors = origin_limits->max_discard_sectors;
3408         limits->max_hw_discard_sectors = origin_limits->max_hw_discard_sectors;
3409         limits->discard_granularity = origin_limits->discard_granularity;
3410         limits->discard_alignment = origin_limits->discard_alignment;
3411         limits->discard_misaligned = origin_limits->discard_misaligned;
3412 }
3413
3414 static void cache_io_hints(struct dm_target *ti, struct queue_limits *limits)
3415 {
3416         struct cache *cache = ti->private;
3417         uint64_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;
3418
3419         /*
3420          * If the system-determined stacked limits are compatible with the
3421          * cache's blocksize (io_opt is a factor) do not override them.
3422          */
3423         if (io_opt_sectors < cache->sectors_per_block ||
3424             do_div(io_opt_sectors, cache->sectors_per_block)) {
3425                 blk_limits_io_min(limits, cache->sectors_per_block << SECTOR_SHIFT);
3426                 blk_limits_io_opt(limits, cache->sectors_per_block << SECTOR_SHIFT);
3427         }
3428
3429         disable_passdown_if_not_supported(cache);
3430         set_discard_limits(cache, limits);
3431 }
3432
3433 /*----------------------------------------------------------------*/
3434
3435 static struct target_type cache_target = {
3436         .name = "cache",
3437         .version = {2, 2, 0},
3438         .module = THIS_MODULE,
3439         .ctr = cache_ctr,
3440         .dtr = cache_dtr,
3441         .map = cache_map,
3442         .end_io = cache_end_io,
3443         .postsuspend = cache_postsuspend,
3444         .preresume = cache_preresume,
3445         .resume = cache_resume,
3446         .status = cache_status,
3447         .message = cache_message,
3448         .iterate_devices = cache_iterate_devices,
3449         .io_hints = cache_io_hints,
3450 };
3451
3452 static int __init dm_cache_init(void)
3453 {
3454         int r;
3455
3456         migration_cache = KMEM_CACHE(dm_cache_migration, 0);
3457         if (!migration_cache)
3458                 return -ENOMEM;
3459
3460         r = dm_register_target(&cache_target);
3461         if (r) {
3462                 kmem_cache_destroy(migration_cache);
3463                 return r;
3464         }
3465
3466         return 0;
3467 }
3468
3469 static void __exit dm_cache_exit(void)
3470 {
3471         dm_unregister_target(&cache_target);
3472         kmem_cache_destroy(migration_cache);
3473 }
3474
3475 module_init(dm_cache_init);
3476 module_exit(dm_cache_exit);
3477
3478 MODULE_DESCRIPTION(DM_NAME " cache target");
3479 MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
3480 MODULE_LICENSE("GPL");