linux/drivers/md/dm-cache-target.c
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   1/*
   2 * Copyright (C) 2012 Red Hat. All rights reserved.
   3 *
   4 * This file is released under the GPL.
   5 */
   6
   7#include "dm.h"
   8#include "dm-bio-prison-v2.h"
   9#include "dm-bio-record.h"
  10#include "dm-cache-metadata.h"
  11
  12#include <linux/dm-io.h>
  13#include <linux/dm-kcopyd.h>
  14#include <linux/jiffies.h>
  15#include <linux/init.h>
  16#include <linux/mempool.h>
  17#include <linux/module.h>
  18#include <linux/rwsem.h>
  19#include <linux/slab.h>
  20#include <linux/vmalloc.h>
  21
  22#define DM_MSG_PREFIX "cache"
  23
  24DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(cache_copy_throttle,
  25        "A percentage of time allocated for copying to and/or from cache");
  26
  27/*----------------------------------------------------------------*/
  28
  29/*
  30 * Glossary:
  31 *
  32 * oblock: index of an origin block
  33 * cblock: index of a cache block
  34 * promotion: movement of a block from origin to cache
  35 * demotion: movement of a block from cache to origin
  36 * migration: movement of a block between the origin and cache device,
  37 *            either direction
  38 */
  39
  40/*----------------------------------------------------------------*/
  41
  42struct io_tracker {
  43        spinlock_t lock;
  44
  45        /*
  46         * Sectors of in-flight IO.
  47         */
  48        sector_t in_flight;
  49
  50        /*
  51         * The time, in jiffies, when this device became idle (if it is
  52         * indeed idle).
  53         */
  54        unsigned long idle_time;
  55        unsigned long last_update_time;
  56};
  57
  58static void iot_init(struct io_tracker *iot)
  59{
  60        spin_lock_init(&iot->lock);
  61        iot->in_flight = 0ul;
  62        iot->idle_time = 0ul;
  63        iot->last_update_time = jiffies;
  64}
  65
  66static bool __iot_idle_for(struct io_tracker *iot, unsigned long jifs)
  67{
  68        if (iot->in_flight)
  69                return false;
  70
  71        return time_after(jiffies, iot->idle_time + jifs);
  72}
  73
  74static bool iot_idle_for(struct io_tracker *iot, unsigned long jifs)
  75{
  76        bool r;
  77
  78        spin_lock_irq(&iot->lock);
  79        r = __iot_idle_for(iot, jifs);
  80        spin_unlock_irq(&iot->lock);
  81
  82        return r;
  83}
  84
  85static void iot_io_begin(struct io_tracker *iot, sector_t len)
  86{
  87        spin_lock_irq(&iot->lock);
  88        iot->in_flight += len;
  89        spin_unlock_irq(&iot->lock);
  90}
  91
  92static void __iot_io_end(struct io_tracker *iot, sector_t len)
  93{
  94        if (!len)
  95                return;
  96
  97        iot->in_flight -= len;
  98        if (!iot->in_flight)
  99                iot->idle_time = jiffies;
 100}
 101
 102static void iot_io_end(struct io_tracker *iot, sector_t len)
 103{
 104        unsigned long flags;
 105
 106        spin_lock_irqsave(&iot->lock, flags);
 107        __iot_io_end(iot, len);
 108        spin_unlock_irqrestore(&iot->lock, flags);
 109}
 110
 111/*----------------------------------------------------------------*/
 112
 113/*
 114 * Represents a chunk of future work.  'input' allows continuations to pass
 115 * values between themselves, typically error values.
 116 */
 117struct continuation {
 118        struct work_struct ws;
 119        blk_status_t input;
 120};
 121
 122static inline void init_continuation(struct continuation *k,
 123                                     void (*fn)(struct work_struct *))
 124{
 125        INIT_WORK(&k->ws, fn);
 126        k->input = 0;
 127}
 128
 129static inline void queue_continuation(struct workqueue_struct *wq,
 130                                      struct continuation *k)
 131{
 132        queue_work(wq, &k->ws);
 133}
 134
 135/*----------------------------------------------------------------*/
 136
 137/*
 138 * The batcher collects together pieces of work that need a particular
 139 * operation to occur before they can proceed (typically a commit).
 140 */
 141struct batcher {
 142        /*
 143         * The operation that everyone is waiting for.
 144         */
 145        blk_status_t (*commit_op)(void *context);
 146        void *commit_context;
 147
 148        /*
 149         * This is how bios should be issued once the commit op is complete
 150         * (accounted_request).
 151         */
 152        void (*issue_op)(struct bio *bio, void *context);
 153        void *issue_context;
 154
 155        /*
 156         * Queued work gets put on here after commit.
 157         */
 158        struct workqueue_struct *wq;
 159
 160        spinlock_t lock;
 161        struct list_head work_items;
 162        struct bio_list bios;
 163        struct work_struct commit_work;
 164
 165        bool commit_scheduled;
 166};
 167
 168static void __commit(struct work_struct *_ws)
 169{
 170        struct batcher *b = container_of(_ws, struct batcher, commit_work);
 171        blk_status_t r;
 172        struct list_head work_items;
 173        struct work_struct *ws, *tmp;
 174        struct continuation *k;
 175        struct bio *bio;
 176        struct bio_list bios;
 177
 178        INIT_LIST_HEAD(&work_items);
 179        bio_list_init(&bios);
 180
 181        /*
 182         * We have to grab these before the commit_op to avoid a race
 183         * condition.
 184         */
 185        spin_lock_irq(&b->lock);
 186        list_splice_init(&b->work_items, &work_items);
 187        bio_list_merge(&bios, &b->bios);
 188        bio_list_init(&b->bios);
 189        b->commit_scheduled = false;
 190        spin_unlock_irq(&b->lock);
 191
 192        r = b->commit_op(b->commit_context);
 193
 194        list_for_each_entry_safe(ws, tmp, &work_items, entry) {
 195                k = container_of(ws, struct continuation, ws);
 196                k->input = r;
 197                INIT_LIST_HEAD(&ws->entry); /* to avoid a WARN_ON */
 198                queue_work(b->wq, ws);
 199        }
 200
 201        while ((bio = bio_list_pop(&bios))) {
 202                if (r) {
 203                        bio->bi_status = r;
 204                        bio_endio(bio);
 205                } else
 206                        b->issue_op(bio, b->issue_context);
 207        }
 208}
 209
 210static void batcher_init(struct batcher *b,
 211                         blk_status_t (*commit_op)(void *),
 212                         void *commit_context,
 213                         void (*issue_op)(struct bio *bio, void *),
 214                         void *issue_context,
 215                         struct workqueue_struct *wq)
 216{
 217        b->commit_op = commit_op;
 218        b->commit_context = commit_context;
 219        b->issue_op = issue_op;
 220        b->issue_context = issue_context;
 221        b->wq = wq;
 222
 223        spin_lock_init(&b->lock);
 224        INIT_LIST_HEAD(&b->work_items);
 225        bio_list_init(&b->bios);
 226        INIT_WORK(&b->commit_work, __commit);
 227        b->commit_scheduled = false;
 228}
 229
 230static void async_commit(struct batcher *b)
 231{
 232        queue_work(b->wq, &b->commit_work);
 233}
 234
 235static void continue_after_commit(struct batcher *b, struct continuation *k)
 236{
 237        bool commit_scheduled;
 238
 239        spin_lock_irq(&b->lock);
 240        commit_scheduled = b->commit_scheduled;
 241        list_add_tail(&k->ws.entry, &b->work_items);
 242        spin_unlock_irq(&b->lock);
 243
 244        if (commit_scheduled)
 245                async_commit(b);
 246}
 247
 248/*
 249 * Bios are errored if commit failed.
 250 */
 251static void issue_after_commit(struct batcher *b, struct bio *bio)
 252{
 253       bool commit_scheduled;
 254
 255       spin_lock_irq(&b->lock);
 256       commit_scheduled = b->commit_scheduled;
 257       bio_list_add(&b->bios, bio);
 258       spin_unlock_irq(&b->lock);
 259
 260       if (commit_scheduled)
 261               async_commit(b);
 262}
 263
 264/*
 265 * Call this if some urgent work is waiting for the commit to complete.
 266 */
 267static void schedule_commit(struct batcher *b)
 268{
 269        bool immediate;
 270
 271        spin_lock_irq(&b->lock);
 272        immediate = !list_empty(&b->work_items) || !bio_list_empty(&b->bios);
 273        b->commit_scheduled = true;
 274        spin_unlock_irq(&b->lock);
 275
 276        if (immediate)
 277                async_commit(b);
 278}
 279
 280/*
 281 * There are a couple of places where we let a bio run, but want to do some
 282 * work before calling its endio function.  We do this by temporarily
 283 * changing the endio fn.
 284 */
 285struct dm_hook_info {
 286        bio_end_io_t *bi_end_io;
 287};
 288
 289static void dm_hook_bio(struct dm_hook_info *h, struct bio *bio,
 290                        bio_end_io_t *bi_end_io, void *bi_private)
 291{
 292        h->bi_end_io = bio->bi_end_io;
 293
 294        bio->bi_end_io = bi_end_io;
 295        bio->bi_private = bi_private;
 296}
 297
 298static void dm_unhook_bio(struct dm_hook_info *h, struct bio *bio)
 299{
 300        bio->bi_end_io = h->bi_end_io;
 301}
 302
 303/*----------------------------------------------------------------*/
 304
 305#define MIGRATION_POOL_SIZE 128
 306#define COMMIT_PERIOD HZ
 307#define MIGRATION_COUNT_WINDOW 10
 308
 309/*
 310 * The block size of the device holding cache data must be
 311 * between 32KB and 1GB.
 312 */
 313#define DATA_DEV_BLOCK_SIZE_MIN_SECTORS (32 * 1024 >> SECTOR_SHIFT)
 314#define DATA_DEV_BLOCK_SIZE_MAX_SECTORS (1024 * 1024 * 1024 >> SECTOR_SHIFT)
 315
 316enum cache_metadata_mode {
 317        CM_WRITE,               /* metadata may be changed */
 318        CM_READ_ONLY,           /* metadata may not be changed */
 319        CM_FAIL
 320};
 321
 322enum cache_io_mode {
 323        /*
 324         * Data is written to cached blocks only.  These blocks are marked
 325         * dirty.  If you lose the cache device you will lose data.
 326         * Potential performance increase for both reads and writes.
 327         */
 328        CM_IO_WRITEBACK,
 329
 330        /*
 331         * Data is written to both cache and origin.  Blocks are never
 332         * dirty.  Potential performance benfit for reads only.
 333         */
 334        CM_IO_WRITETHROUGH,
 335
 336        /*
 337         * A degraded mode useful for various cache coherency situations
 338         * (eg, rolling back snapshots).  Reads and writes always go to the
 339         * origin.  If a write goes to a cached oblock, then the cache
 340         * block is invalidated.
 341         */
 342        CM_IO_PASSTHROUGH
 343};
 344
 345struct cache_features {
 346        enum cache_metadata_mode mode;
 347        enum cache_io_mode io_mode;
 348        unsigned metadata_version;
 349        bool discard_passdown:1;
 350};
 351
 352struct cache_stats {
 353        atomic_t read_hit;
 354        atomic_t read_miss;
 355        atomic_t write_hit;
 356        atomic_t write_miss;
 357        atomic_t demotion;
 358        atomic_t promotion;
 359        atomic_t writeback;
 360        atomic_t copies_avoided;
 361        atomic_t cache_cell_clash;
 362        atomic_t commit_count;
 363        atomic_t discard_count;
 364};
 365
 366struct cache {
 367        struct dm_target *ti;
 368        spinlock_t lock;
 369
 370        /*
 371         * Fields for converting from sectors to blocks.
 372         */
 373        int sectors_per_block_shift;
 374        sector_t sectors_per_block;
 375
 376        struct dm_cache_metadata *cmd;
 377
 378        /*
 379         * Metadata is written to this device.
 380         */
 381        struct dm_dev *metadata_dev;
 382
 383        /*
 384         * The slower of the two data devices.  Typically a spindle.
 385         */
 386        struct dm_dev *origin_dev;
 387
 388        /*
 389         * The faster of the two data devices.  Typically an SSD.
 390         */
 391        struct dm_dev *cache_dev;
 392
 393        /*
 394         * Size of the origin device in _complete_ blocks and native sectors.
 395         */
 396        dm_oblock_t origin_blocks;
 397        sector_t origin_sectors;
 398
 399        /*
 400         * Size of the cache device in blocks.
 401         */
 402        dm_cblock_t cache_size;
 403
 404        /*
 405         * Invalidation fields.
 406         */
 407        spinlock_t invalidation_lock;
 408        struct list_head invalidation_requests;
 409
 410        sector_t migration_threshold;
 411        wait_queue_head_t migration_wait;
 412        atomic_t nr_allocated_migrations;
 413
 414        /*
 415         * The number of in flight migrations that are performing
 416         * background io. eg, promotion, writeback.
 417         */
 418        atomic_t nr_io_migrations;
 419
 420        struct bio_list deferred_bios;
 421
 422        struct rw_semaphore quiesce_lock;
 423
 424        /*
 425         * origin_blocks entries, discarded if set.
 426         */
 427        dm_dblock_t discard_nr_blocks;
 428        unsigned long *discard_bitset;
 429        uint32_t discard_block_size; /* a power of 2 times sectors per block */
 430
 431        /*
 432         * Rather than reconstructing the table line for the status we just
 433         * save it and regurgitate.
 434         */
 435        unsigned nr_ctr_args;
 436        const char **ctr_args;
 437
 438        struct dm_kcopyd_client *copier;
 439        struct work_struct deferred_bio_worker;
 440        struct work_struct migration_worker;
 441        struct workqueue_struct *wq;
 442        struct delayed_work waker;
 443        struct dm_bio_prison_v2 *prison;
 444
 445        /*
 446         * cache_size entries, dirty if set
 447         */
 448        unsigned long *dirty_bitset;
 449        atomic_t nr_dirty;
 450
 451        unsigned policy_nr_args;
 452        struct dm_cache_policy *policy;
 453
 454        /*
 455         * Cache features such as write-through.
 456         */
 457        struct cache_features features;
 458
 459        struct cache_stats stats;
 460
 461        bool need_tick_bio:1;
 462        bool sized:1;
 463        bool invalidate:1;
 464        bool commit_requested:1;
 465        bool loaded_mappings:1;
 466        bool loaded_discards:1;
 467
 468        struct rw_semaphore background_work_lock;
 469
 470        struct batcher committer;
 471        struct work_struct commit_ws;
 472
 473        struct io_tracker tracker;
 474
 475        mempool_t migration_pool;
 476
 477        struct bio_set bs;
 478};
 479
 480struct per_bio_data {
 481        bool tick:1;
 482        unsigned req_nr:2;
 483        struct dm_bio_prison_cell_v2 *cell;
 484        struct dm_hook_info hook_info;
 485        sector_t len;
 486};
 487
 488struct dm_cache_migration {
 489        struct continuation k;
 490        struct cache *cache;
 491
 492        struct policy_work *op;
 493        struct bio *overwrite_bio;
 494        struct dm_bio_prison_cell_v2 *cell;
 495
 496        dm_cblock_t invalidate_cblock;
 497        dm_oblock_t invalidate_oblock;
 498};
 499
 500/*----------------------------------------------------------------*/
 501
 502static bool writethrough_mode(struct cache *cache)
 503{
 504        return cache->features.io_mode == CM_IO_WRITETHROUGH;
 505}
 506
 507static bool writeback_mode(struct cache *cache)
 508{
 509        return cache->features.io_mode == CM_IO_WRITEBACK;
 510}
 511
 512static inline bool passthrough_mode(struct cache *cache)
 513{
 514        return unlikely(cache->features.io_mode == CM_IO_PASSTHROUGH);
 515}
 516
 517/*----------------------------------------------------------------*/
 518
 519static void wake_deferred_bio_worker(struct cache *cache)
 520{
 521        queue_work(cache->wq, &cache->deferred_bio_worker);
 522}
 523
 524static void wake_migration_worker(struct cache *cache)
 525{
 526        if (passthrough_mode(cache))
 527                return;
 528
 529        queue_work(cache->wq, &cache->migration_worker);
 530}
 531
 532/*----------------------------------------------------------------*/
 533
 534static struct dm_bio_prison_cell_v2 *alloc_prison_cell(struct cache *cache)
 535{
 536        return dm_bio_prison_alloc_cell_v2(cache->prison, GFP_NOIO);
 537}
 538
 539static void free_prison_cell(struct cache *cache, struct dm_bio_prison_cell_v2 *cell)
 540{
 541        dm_bio_prison_free_cell_v2(cache->prison, cell);
 542}
 543
 544static struct dm_cache_migration *alloc_migration(struct cache *cache)
 545{
 546        struct dm_cache_migration *mg;
 547
 548        mg = mempool_alloc(&cache->migration_pool, GFP_NOIO);
 549
 550        memset(mg, 0, sizeof(*mg));
 551
 552        mg->cache = cache;
 553        atomic_inc(&cache->nr_allocated_migrations);
 554
 555        return mg;
 556}
 557
 558static void free_migration(struct dm_cache_migration *mg)
 559{
 560        struct cache *cache = mg->cache;
 561
 562        if (atomic_dec_and_test(&cache->nr_allocated_migrations))
 563                wake_up(&cache->migration_wait);
 564
 565        mempool_free(mg, &cache->migration_pool);
 566}
 567
 568/*----------------------------------------------------------------*/
 569
 570static inline dm_oblock_t oblock_succ(dm_oblock_t b)
 571{
 572        return to_oblock(from_oblock(b) + 1ull);
 573}
 574
 575static void build_key(dm_oblock_t begin, dm_oblock_t end, struct dm_cell_key_v2 *key)
 576{
 577        key->virtual = 0;
 578        key->dev = 0;
 579        key->block_begin = from_oblock(begin);
 580        key->block_end = from_oblock(end);
 581}
 582
 583/*
 584 * We have two lock levels.  Level 0, which is used to prevent WRITEs, and
 585 * level 1 which prevents *both* READs and WRITEs.
 586 */
 587#define WRITE_LOCK_LEVEL 0
 588#define READ_WRITE_LOCK_LEVEL 1
 589
 590static unsigned lock_level(struct bio *bio)
 591{
 592        return bio_data_dir(bio) == WRITE ?
 593                WRITE_LOCK_LEVEL :
 594                READ_WRITE_LOCK_LEVEL;
 595}
 596
 597/*----------------------------------------------------------------
 598 * Per bio data
 599 *--------------------------------------------------------------*/
 600
 601static struct per_bio_data *get_per_bio_data(struct bio *bio)
 602{
 603        struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
 604        BUG_ON(!pb);
 605        return pb;
 606}
 607
 608static struct per_bio_data *init_per_bio_data(struct bio *bio)
 609{
 610        struct per_bio_data *pb = get_per_bio_data(bio);
 611
 612        pb->tick = false;
 613        pb->req_nr = dm_bio_get_target_bio_nr(bio);
 614        pb->cell = NULL;
 615        pb->len = 0;
 616
 617        return pb;
 618}
 619
 620/*----------------------------------------------------------------*/
 621
 622static void defer_bio(struct cache *cache, struct bio *bio)
 623{
 624        spin_lock_irq(&cache->lock);
 625        bio_list_add(&cache->deferred_bios, bio);
 626        spin_unlock_irq(&cache->lock);
 627
 628        wake_deferred_bio_worker(cache);
 629}
 630
 631static void defer_bios(struct cache *cache, struct bio_list *bios)
 632{
 633        spin_lock_irq(&cache->lock);
 634        bio_list_merge(&cache->deferred_bios, bios);
 635        bio_list_init(bios);
 636        spin_unlock_irq(&cache->lock);
 637
 638        wake_deferred_bio_worker(cache);
 639}
 640
 641/*----------------------------------------------------------------*/
 642
 643static bool bio_detain_shared(struct cache *cache, dm_oblock_t oblock, struct bio *bio)
 644{
 645        bool r;
 646        struct per_bio_data *pb;
 647        struct dm_cell_key_v2 key;
 648        dm_oblock_t end = to_oblock(from_oblock(oblock) + 1ULL);
 649        struct dm_bio_prison_cell_v2 *cell_prealloc, *cell;
 650
 651        cell_prealloc = alloc_prison_cell(cache); /* FIXME: allow wait if calling from worker */
 652
 653        build_key(oblock, end, &key);
 654        r = dm_cell_get_v2(cache->prison, &key, lock_level(bio), bio, cell_prealloc, &cell);
 655        if (!r) {
 656                /*
 657                 * Failed to get the lock.
 658                 */
 659                free_prison_cell(cache, cell_prealloc);
 660                return r;
 661        }
 662
 663        if (cell != cell_prealloc)
 664                free_prison_cell(cache, cell_prealloc);
 665
 666        pb = get_per_bio_data(bio);
 667        pb->cell = cell;
 668
 669        return r;
 670}
 671
 672/*----------------------------------------------------------------*/
 673
 674static bool is_dirty(struct cache *cache, dm_cblock_t b)
 675{
 676        return test_bit(from_cblock(b), cache->dirty_bitset);
 677}
 678
 679static void set_dirty(struct cache *cache, dm_cblock_t cblock)
 680{
 681        if (!test_and_set_bit(from_cblock(cblock), cache->dirty_bitset)) {
 682                atomic_inc(&cache->nr_dirty);
 683                policy_set_dirty(cache->policy, cblock);
 684        }
 685}
 686
 687/*
 688 * These two are called when setting after migrations to force the policy
 689 * and dirty bitset to be in sync.
 690 */
 691static void force_set_dirty(struct cache *cache, dm_cblock_t cblock)
 692{
 693        if (!test_and_set_bit(from_cblock(cblock), cache->dirty_bitset))
 694                atomic_inc(&cache->nr_dirty);
 695        policy_set_dirty(cache->policy, cblock);
 696}
 697
 698static void force_clear_dirty(struct cache *cache, dm_cblock_t cblock)
 699{
 700        if (test_and_clear_bit(from_cblock(cblock), cache->dirty_bitset)) {
 701                if (atomic_dec_return(&cache->nr_dirty) == 0)
 702                        dm_table_event(cache->ti->table);
 703        }
 704
 705        policy_clear_dirty(cache->policy, cblock);
 706}
 707
 708/*----------------------------------------------------------------*/
 709
 710static bool block_size_is_power_of_two(struct cache *cache)
 711{
 712        return cache->sectors_per_block_shift >= 0;
 713}
 714
 715static dm_block_t block_div(dm_block_t b, uint32_t n)
 716{
 717        do_div(b, n);
 718
 719        return b;
 720}
 721
 722static dm_block_t oblocks_per_dblock(struct cache *cache)
 723{
 724        dm_block_t oblocks = cache->discard_block_size;
 725
 726        if (block_size_is_power_of_two(cache))
 727                oblocks >>= cache->sectors_per_block_shift;
 728        else
 729                oblocks = block_div(oblocks, cache->sectors_per_block);
 730
 731        return oblocks;
 732}
 733
 734static dm_dblock_t oblock_to_dblock(struct cache *cache, dm_oblock_t oblock)
 735{
 736        return to_dblock(block_div(from_oblock(oblock),
 737                                   oblocks_per_dblock(cache)));
 738}
 739
 740static void set_discard(struct cache *cache, dm_dblock_t b)
 741{
 742        BUG_ON(from_dblock(b) >= from_dblock(cache->discard_nr_blocks));
 743        atomic_inc(&cache->stats.discard_count);
 744
 745        spin_lock_irq(&cache->lock);
 746        set_bit(from_dblock(b), cache->discard_bitset);
 747        spin_unlock_irq(&cache->lock);
 748}
 749
 750static void clear_discard(struct cache *cache, dm_dblock_t b)
 751{
 752        spin_lock_irq(&cache->lock);
 753        clear_bit(from_dblock(b), cache->discard_bitset);
 754        spin_unlock_irq(&cache->lock);
 755}
 756
 757static bool is_discarded(struct cache *cache, dm_dblock_t b)
 758{
 759        int r;
 760        spin_lock_irq(&cache->lock);
 761        r = test_bit(from_dblock(b), cache->discard_bitset);
 762        spin_unlock_irq(&cache->lock);
 763
 764        return r;
 765}
 766
 767static bool is_discarded_oblock(struct cache *cache, dm_oblock_t b)
 768{
 769        int r;
 770        spin_lock_irq(&cache->lock);
 771        r = test_bit(from_dblock(oblock_to_dblock(cache, b)),
 772                     cache->discard_bitset);
 773        spin_unlock_irq(&cache->lock);
 774
 775        return r;
 776}
 777
 778/*----------------------------------------------------------------
 779 * Remapping
 780 *--------------------------------------------------------------*/
 781static void remap_to_origin(struct cache *cache, struct bio *bio)
 782{
 783        bio_set_dev(bio, cache->origin_dev->bdev);
 784}
 785
 786static void remap_to_cache(struct cache *cache, struct bio *bio,
 787                           dm_cblock_t cblock)
 788{
 789        sector_t bi_sector = bio->bi_iter.bi_sector;
 790        sector_t block = from_cblock(cblock);
 791
 792        bio_set_dev(bio, cache->cache_dev->bdev);
 793        if (!block_size_is_power_of_two(cache))
 794                bio->bi_iter.bi_sector =
 795                        (block * cache->sectors_per_block) +
 796                        sector_div(bi_sector, cache->sectors_per_block);
 797        else
 798                bio->bi_iter.bi_sector =
 799                        (block << cache->sectors_per_block_shift) |
 800                        (bi_sector & (cache->sectors_per_block - 1));
 801}
 802
 803static void check_if_tick_bio_needed(struct cache *cache, struct bio *bio)
 804{
 805        struct per_bio_data *pb;
 806
 807        spin_lock_irq(&cache->lock);
 808        if (cache->need_tick_bio && !op_is_flush(bio->bi_opf) &&
 809            bio_op(bio) != REQ_OP_DISCARD) {
 810                pb = get_per_bio_data(bio);
 811                pb->tick = true;
 812                cache->need_tick_bio = false;
 813        }
 814        spin_unlock_irq(&cache->lock);
 815}
 816
 817static void __remap_to_origin_clear_discard(struct cache *cache, struct bio *bio,
 818                                            dm_oblock_t oblock, bool bio_has_pbd)
 819{
 820        if (bio_has_pbd)
 821                check_if_tick_bio_needed(cache, bio);
 822        remap_to_origin(cache, bio);
 823        if (bio_data_dir(bio) == WRITE)
 824                clear_discard(cache, oblock_to_dblock(cache, oblock));
 825}
 826
 827static void remap_to_origin_clear_discard(struct cache *cache, struct bio *bio,
 828                                          dm_oblock_t oblock)
 829{
 830        // FIXME: check_if_tick_bio_needed() is called way too much through this interface
 831        __remap_to_origin_clear_discard(cache, bio, oblock, true);
 832}
 833
 834static void remap_to_cache_dirty(struct cache *cache, struct bio *bio,
 835                                 dm_oblock_t oblock, dm_cblock_t cblock)
 836{
 837        check_if_tick_bio_needed(cache, bio);
 838        remap_to_cache(cache, bio, cblock);
 839        if (bio_data_dir(bio) == WRITE) {
 840                set_dirty(cache, cblock);
 841                clear_discard(cache, oblock_to_dblock(cache, oblock));
 842        }
 843}
 844
 845static dm_oblock_t get_bio_block(struct cache *cache, struct bio *bio)
 846{
 847        sector_t block_nr = bio->bi_iter.bi_sector;
 848
 849        if (!block_size_is_power_of_two(cache))
 850                (void) sector_div(block_nr, cache->sectors_per_block);
 851        else
 852                block_nr >>= cache->sectors_per_block_shift;
 853
 854        return to_oblock(block_nr);
 855}
 856
 857static bool accountable_bio(struct cache *cache, struct bio *bio)
 858{
 859        return bio_op(bio) != REQ_OP_DISCARD;
 860}
 861
 862static void accounted_begin(struct cache *cache, struct bio *bio)
 863{
 864        struct per_bio_data *pb;
 865
 866        if (accountable_bio(cache, bio)) {
 867                pb = get_per_bio_data(bio);
 868                pb->len = bio_sectors(bio);
 869                iot_io_begin(&cache->tracker, pb->len);
 870        }
 871}
 872
 873static void accounted_complete(struct cache *cache, struct bio *bio)
 874{
 875        struct per_bio_data *pb = get_per_bio_data(bio);
 876
 877        iot_io_end(&cache->tracker, pb->len);
 878}
 879
 880static void accounted_request(struct cache *cache, struct bio *bio)
 881{
 882        accounted_begin(cache, bio);
 883        submit_bio_noacct(bio);
 884}
 885
 886static void issue_op(struct bio *bio, void *context)
 887{
 888        struct cache *cache = context;
 889        accounted_request(cache, bio);
 890}
 891
 892/*
 893 * When running in writethrough mode we need to send writes to clean blocks
 894 * to both the cache and origin devices.  Clone the bio and send them in parallel.
 895 */
 896static void remap_to_origin_and_cache(struct cache *cache, struct bio *bio,
 897                                      dm_oblock_t oblock, dm_cblock_t cblock)
 898{
 899        struct bio *origin_bio = bio_clone_fast(bio, GFP_NOIO, &cache->bs);
 900
 901        BUG_ON(!origin_bio);
 902
 903        bio_chain(origin_bio, bio);
 904        /*
 905         * Passing false to __remap_to_origin_clear_discard() skips
 906         * all code that might use per_bio_data (since clone doesn't have it)
 907         */
 908        __remap_to_origin_clear_discard(cache, origin_bio, oblock, false);
 909        submit_bio(origin_bio);
 910
 911        remap_to_cache(cache, bio, cblock);
 912}
 913
 914/*----------------------------------------------------------------
 915 * Failure modes
 916 *--------------------------------------------------------------*/
 917static enum cache_metadata_mode get_cache_mode(struct cache *cache)
 918{
 919        return cache->features.mode;
 920}
 921
 922static const char *cache_device_name(struct cache *cache)
 923{
 924        return dm_table_device_name(cache->ti->table);
 925}
 926
 927static void notify_mode_switch(struct cache *cache, enum cache_metadata_mode mode)
 928{
 929        const char *descs[] = {
 930                "write",
 931                "read-only",
 932                "fail"
 933        };
 934
 935        dm_table_event(cache->ti->table);
 936        DMINFO("%s: switching cache to %s mode",
 937               cache_device_name(cache), descs[(int)mode]);
 938}
 939
 940static void set_cache_mode(struct cache *cache, enum cache_metadata_mode new_mode)
 941{
 942        bool needs_check;
 943        enum cache_metadata_mode old_mode = get_cache_mode(cache);
 944
 945        if (dm_cache_metadata_needs_check(cache->cmd, &needs_check)) {
 946                DMERR("%s: unable to read needs_check flag, setting failure mode.",
 947                      cache_device_name(cache));
 948                new_mode = CM_FAIL;
 949        }
 950
 951        if (new_mode == CM_WRITE && needs_check) {
 952                DMERR("%s: unable to switch cache to write mode until repaired.",
 953                      cache_device_name(cache));
 954                if (old_mode != new_mode)
 955                        new_mode = old_mode;
 956                else
 957                        new_mode = CM_READ_ONLY;
 958        }
 959
 960        /* Never move out of fail mode */
 961        if (old_mode == CM_FAIL)
 962                new_mode = CM_FAIL;
 963
 964        switch (new_mode) {
 965        case CM_FAIL:
 966        case CM_READ_ONLY:
 967                dm_cache_metadata_set_read_only(cache->cmd);
 968                break;
 969
 970        case CM_WRITE:
 971                dm_cache_metadata_set_read_write(cache->cmd);
 972                break;
 973        }
 974
 975        cache->features.mode = new_mode;
 976
 977        if (new_mode != old_mode)
 978                notify_mode_switch(cache, new_mode);
 979}
 980
 981static void abort_transaction(struct cache *cache)
 982{
 983        const char *dev_name = cache_device_name(cache);
 984
 985        if (get_cache_mode(cache) >= CM_READ_ONLY)
 986                return;
 987
 988        if (dm_cache_metadata_set_needs_check(cache->cmd)) {
 989                DMERR("%s: failed to set 'needs_check' flag in metadata", dev_name);
 990                set_cache_mode(cache, CM_FAIL);
 991        }
 992
 993        DMERR_LIMIT("%s: aborting current metadata transaction", dev_name);
 994        if (dm_cache_metadata_abort(cache->cmd)) {
 995                DMERR("%s: failed to abort metadata transaction", dev_name);
 996                set_cache_mode(cache, CM_FAIL);
 997        }
 998}
 999
1000static void metadata_operation_failed(struct cache *cache, const char *op, int r)
1001{
1002        DMERR_LIMIT("%s: metadata operation '%s' failed: error = %d",
1003                    cache_device_name(cache), op, r);
1004        abort_transaction(cache);
1005        set_cache_mode(cache, CM_READ_ONLY);
1006}
1007
1008/*----------------------------------------------------------------*/
1009
1010static void load_stats(struct cache *cache)
1011{
1012        struct dm_cache_statistics stats;
1013
1014        dm_cache_metadata_get_stats(cache->cmd, &stats);
1015        atomic_set(&cache->stats.read_hit, stats.read_hits);
1016        atomic_set(&cache->stats.read_miss, stats.read_misses);
1017        atomic_set(&cache->stats.write_hit, stats.write_hits);
1018        atomic_set(&cache->stats.write_miss, stats.write_misses);
1019}
1020
1021static void save_stats(struct cache *cache)
1022{
1023        struct dm_cache_statistics stats;
1024
1025        if (get_cache_mode(cache) >= CM_READ_ONLY)
1026                return;
1027
1028        stats.read_hits = atomic_read(&cache->stats.read_hit);
1029        stats.read_misses = atomic_read(&cache->stats.read_miss);
1030        stats.write_hits = atomic_read(&cache->stats.write_hit);
1031        stats.write_misses = atomic_read(&cache->stats.write_miss);
1032
1033        dm_cache_metadata_set_stats(cache->cmd, &stats);
1034}
1035
1036static void update_stats(struct cache_stats *stats, enum policy_operation op)
1037{
1038        switch (op) {
1039        case POLICY_PROMOTE:
1040                atomic_inc(&stats->promotion);
1041                break;
1042
1043        case POLICY_DEMOTE:
1044                atomic_inc(&stats->demotion);
1045                break;
1046
1047        case POLICY_WRITEBACK:
1048                atomic_inc(&stats->writeback);
1049                break;
1050        }
1051}
1052
1053/*----------------------------------------------------------------
1054 * Migration processing
1055 *
1056 * Migration covers moving data from the origin device to the cache, or
1057 * vice versa.
1058 *--------------------------------------------------------------*/
1059
1060static void inc_io_migrations(struct cache *cache)
1061{
1062        atomic_inc(&cache->nr_io_migrations);
1063}
1064
1065static void dec_io_migrations(struct cache *cache)
1066{
1067        atomic_dec(&cache->nr_io_migrations);
1068}
1069
1070static bool discard_or_flush(struct bio *bio)
1071{
1072        return bio_op(bio) == REQ_OP_DISCARD || op_is_flush(bio->bi_opf);
1073}
1074
1075static void calc_discard_block_range(struct cache *cache, struct bio *bio,
1076                                     dm_dblock_t *b, dm_dblock_t *e)
1077{
1078        sector_t sb = bio->bi_iter.bi_sector;
1079        sector_t se = bio_end_sector(bio);
1080
1081        *b = to_dblock(dm_sector_div_up(sb, cache->discard_block_size));
1082
1083        if (se - sb < cache->discard_block_size)
1084                *e = *b;
1085        else
1086                *e = to_dblock(block_div(se, cache->discard_block_size));
1087}
1088
1089/*----------------------------------------------------------------*/
1090
1091static void prevent_background_work(struct cache *cache)
1092{
1093        lockdep_off();
1094        down_write(&cache->background_work_lock);
1095        lockdep_on();
1096}
1097
1098static void allow_background_work(struct cache *cache)
1099{
1100        lockdep_off();
1101        up_write(&cache->background_work_lock);
1102        lockdep_on();
1103}
1104
1105static bool background_work_begin(struct cache *cache)
1106{
1107        bool r;
1108
1109        lockdep_off();
1110        r = down_read_trylock(&cache->background_work_lock);
1111        lockdep_on();
1112
1113        return r;
1114}
1115
1116static void background_work_end(struct cache *cache)
1117{
1118        lockdep_off();
1119        up_read(&cache->background_work_lock);
1120        lockdep_on();
1121}
1122
1123/*----------------------------------------------------------------*/
1124
1125static bool bio_writes_complete_block(struct cache *cache, struct bio *bio)
1126{
1127        return (bio_data_dir(bio) == WRITE) &&
1128                (bio->bi_iter.bi_size == (cache->sectors_per_block << SECTOR_SHIFT));
1129}
1130
1131static bool optimisable_bio(struct cache *cache, struct bio *bio, dm_oblock_t block)
1132{
1133        return writeback_mode(cache) &&
1134                (is_discarded_oblock(cache, block) || bio_writes_complete_block(cache, bio));
1135}
1136
1137static void quiesce(struct dm_cache_migration *mg,
1138                    void (*continuation)(struct work_struct *))
1139{
1140        init_continuation(&mg->k, continuation);
1141        dm_cell_quiesce_v2(mg->cache->prison, mg->cell, &mg->k.ws);
1142}
1143
1144static struct dm_cache_migration *ws_to_mg(struct work_struct *ws)
1145{
1146        struct continuation *k = container_of(ws, struct continuation, ws);
1147        return container_of(k, struct dm_cache_migration, k);
1148}
1149
1150static void copy_complete(int read_err, unsigned long write_err, void *context)
1151{
1152        struct dm_cache_migration *mg = container_of(context, struct dm_cache_migration, k);
1153
1154        if (read_err || write_err)
1155                mg->k.input = BLK_STS_IOERR;
1156
1157        queue_continuation(mg->cache->wq, &mg->k);
1158}
1159
1160static void copy(struct dm_cache_migration *mg, bool promote)
1161{
1162        struct dm_io_region o_region, c_region;
1163        struct cache *cache = mg->cache;
1164
1165        o_region.bdev = cache->origin_dev->bdev;
1166        o_region.sector = from_oblock(mg->op->oblock) * cache->sectors_per_block;
1167        o_region.count = cache->sectors_per_block;
1168
1169        c_region.bdev = cache->cache_dev->bdev;
1170        c_region.sector = from_cblock(mg->op->cblock) * cache->sectors_per_block;
1171        c_region.count = cache->sectors_per_block;
1172
1173        if (promote)
1174                dm_kcopyd_copy(cache->copier, &o_region, 1, &c_region, 0, copy_complete, &mg->k);
1175        else
1176                dm_kcopyd_copy(cache->copier, &c_region, 1, &o_region, 0, copy_complete, &mg->k);
1177}
1178
1179static void bio_drop_shared_lock(struct cache *cache, struct bio *bio)
1180{
1181        struct per_bio_data *pb = get_per_bio_data(bio);
1182
1183        if (pb->cell && dm_cell_put_v2(cache->prison, pb->cell))
1184                free_prison_cell(cache, pb->cell);
1185        pb->cell = NULL;
1186}
1187
1188static void overwrite_endio(struct bio *bio)
1189{
1190        struct dm_cache_migration *mg = bio->bi_private;
1191        struct cache *cache = mg->cache;
1192        struct per_bio_data *pb = get_per_bio_data(bio);
1193
1194        dm_unhook_bio(&pb->hook_info, bio);
1195
1196        if (bio->bi_status)
1197                mg->k.input = bio->bi_status;
1198
1199        queue_continuation(cache->wq, &mg->k);
1200}
1201
1202static void overwrite(struct dm_cache_migration *mg,
1203                      void (*continuation)(struct work_struct *))
1204{
1205        struct bio *bio = mg->overwrite_bio;
1206        struct per_bio_data *pb = get_per_bio_data(bio);
1207
1208        dm_hook_bio(&pb->hook_info, bio, overwrite_endio, mg);
1209
1210        /*
1211         * The overwrite bio is part of the copy operation, as such it does
1212         * not set/clear discard or dirty flags.
1213         */
1214        if (mg->op->op == POLICY_PROMOTE)
1215                remap_to_cache(mg->cache, bio, mg->op->cblock);
1216        else
1217                remap_to_origin(mg->cache, bio);
1218
1219        init_continuation(&mg->k, continuation);
1220        accounted_request(mg->cache, bio);
1221}
1222
1223/*
1224 * Migration steps:
1225 *
1226 * 1) exclusive lock preventing WRITEs
1227 * 2) quiesce
1228 * 3) copy or issue overwrite bio
1229 * 4) upgrade to exclusive lock preventing READs and WRITEs
1230 * 5) quiesce
1231 * 6) update metadata and commit
1232 * 7) unlock
1233 */
1234static void mg_complete(struct dm_cache_migration *mg, bool success)
1235{
1236        struct bio_list bios;
1237        struct cache *cache = mg->cache;
1238        struct policy_work *op = mg->op;
1239        dm_cblock_t cblock = op->cblock;
1240
1241        if (success)
1242                update_stats(&cache->stats, op->op);
1243
1244        switch (op->op) {
1245        case POLICY_PROMOTE:
1246                clear_discard(cache, oblock_to_dblock(cache, op->oblock));
1247                policy_complete_background_work(cache->policy, op, success);
1248
1249                if (mg->overwrite_bio) {
1250                        if (success)
1251                                force_set_dirty(cache, cblock);
1252                        else if (mg->k.input)
1253                                mg->overwrite_bio->bi_status = mg->k.input;
1254                        else
1255                                mg->overwrite_bio->bi_status = BLK_STS_IOERR;
1256                        bio_endio(mg->overwrite_bio);
1257                } else {
1258                        if (success)
1259                                force_clear_dirty(cache, cblock);
1260                        dec_io_migrations(cache);
1261                }
1262                break;
1263
1264        case POLICY_DEMOTE:
1265                /*
1266                 * We clear dirty here to update the nr_dirty counter.
1267                 */
1268                if (success)
1269                        force_clear_dirty(cache, cblock);
1270                policy_complete_background_work(cache->policy, op, success);
1271                dec_io_migrations(cache);
1272                break;
1273
1274        case POLICY_WRITEBACK:
1275                if (success)
1276                        force_clear_dirty(cache, cblock);
1277                policy_complete_background_work(cache->policy, op, success);
1278                dec_io_migrations(cache);
1279                break;
1280        }
1281
1282        bio_list_init(&bios);
1283        if (mg->cell) {
1284                if (dm_cell_unlock_v2(cache->prison, mg->cell, &bios))
1285                        free_prison_cell(cache, mg->cell);
1286        }
1287
1288        free_migration(mg);
1289        defer_bios(cache, &bios);
1290        wake_migration_worker(cache);
1291
1292        background_work_end(cache);
1293}
1294
1295static void mg_success(struct work_struct *ws)
1296{
1297        struct dm_cache_migration *mg = ws_to_mg(ws);
1298        mg_complete(mg, mg->k.input == 0);
1299}
1300
1301static void mg_update_metadata(struct work_struct *ws)
1302{
1303        int r;
1304        struct dm_cache_migration *mg = ws_to_mg(ws);
1305        struct cache *cache = mg->cache;
1306        struct policy_work *op = mg->op;
1307
1308        switch (op->op) {
1309        case POLICY_PROMOTE:
1310                r = dm_cache_insert_mapping(cache->cmd, op->cblock, op->oblock);
1311                if (r) {
1312                        DMERR_LIMIT("%s: migration failed; couldn't insert mapping",
1313                                    cache_device_name(cache));
1314                        metadata_operation_failed(cache, "dm_cache_insert_mapping", r);
1315
1316                        mg_complete(mg, false);
1317                        return;
1318                }
1319                mg_complete(mg, true);
1320                break;
1321
1322        case POLICY_DEMOTE:
1323                r = dm_cache_remove_mapping(cache->cmd, op->cblock);
1324                if (r) {
1325                        DMERR_LIMIT("%s: migration failed; couldn't update on disk metadata",
1326                                    cache_device_name(cache));
1327                        metadata_operation_failed(cache, "dm_cache_remove_mapping", r);
1328
1329                        mg_complete(mg, false);
1330                        return;
1331                }
1332
1333                /*
1334                 * It would be nice if we only had to commit when a REQ_FLUSH
1335                 * comes through.  But there's one scenario that we have to
1336                 * look out for:
1337                 *
1338                 * - vblock x in a cache block
1339                 * - domotion occurs
1340                 * - cache block gets reallocated and over written
1341                 * - crash
1342                 *
1343                 * When we recover, because there was no commit the cache will
1344                 * rollback to having the data for vblock x in the cache block.
1345                 * But the cache block has since been overwritten, so it'll end
1346                 * up pointing to data that was never in 'x' during the history
1347                 * of the device.
1348                 *
1349                 * To avoid this issue we require a commit as part of the
1350                 * demotion operation.
1351                 */
1352                init_continuation(&mg->k, mg_success);
1353                continue_after_commit(&cache->committer, &mg->k);
1354                schedule_commit(&cache->committer);
1355                break;
1356
1357        case POLICY_WRITEBACK:
1358                mg_complete(mg, true);
1359                break;
1360        }
1361}
1362
1363static void mg_update_metadata_after_copy(struct work_struct *ws)
1364{
1365        struct dm_cache_migration *mg = ws_to_mg(ws);
1366
1367        /*
1368         * Did the copy succeed?
1369         */
1370        if (mg->k.input)
1371                mg_complete(mg, false);
1372        else
1373                mg_update_metadata(ws);
1374}
1375
1376static void mg_upgrade_lock(struct work_struct *ws)
1377{
1378        int r;
1379        struct dm_cache_migration *mg = ws_to_mg(ws);
1380
1381        /*
1382         * Did the copy succeed?
1383         */
1384        if (mg->k.input)
1385                mg_complete(mg, false);
1386
1387        else {
1388                /*
1389                 * Now we want the lock to prevent both reads and writes.
1390                 */
1391                r = dm_cell_lock_promote_v2(mg->cache->prison, mg->cell,
1392                                            READ_WRITE_LOCK_LEVEL);
1393                if (r < 0)
1394                        mg_complete(mg, false);
1395
1396                else if (r)
1397                        quiesce(mg, mg_update_metadata);
1398
1399                else
1400                        mg_update_metadata(ws);
1401        }
1402}
1403
1404static void mg_full_copy(struct work_struct *ws)
1405{
1406        struct dm_cache_migration *mg = ws_to_mg(ws);
1407        struct cache *cache = mg->cache;
1408        struct policy_work *op = mg->op;
1409        bool is_policy_promote = (op->op == POLICY_PROMOTE);
1410
1411        if ((!is_policy_promote && !is_dirty(cache, op->cblock)) ||
1412            is_discarded_oblock(cache, op->oblock)) {
1413                mg_upgrade_lock(ws);
1414                return;
1415        }
1416
1417        init_continuation(&mg->k, mg_upgrade_lock);
1418        copy(mg, is_policy_promote);
1419}
1420
1421static void mg_copy(struct work_struct *ws)
1422{
1423        struct dm_cache_migration *mg = ws_to_mg(ws);
1424
1425        if (mg->overwrite_bio) {
1426                /*
1427                 * No exclusive lock was held when we last checked if the bio
1428                 * was optimisable.  So we have to check again in case things
1429                 * have changed (eg, the block may no longer be discarded).
1430                 */
1431                if (!optimisable_bio(mg->cache, mg->overwrite_bio, mg->op->oblock)) {
1432                        /*
1433                         * Fallback to a real full copy after doing some tidying up.
1434                         */
1435                        bool rb = bio_detain_shared(mg->cache, mg->op->oblock, mg->overwrite_bio);
1436                        BUG_ON(rb); /* An exclussive lock must _not_ be held for this block */
1437                        mg->overwrite_bio = NULL;
1438                        inc_io_migrations(mg->cache);
1439                        mg_full_copy(ws);
1440                        return;
1441                }
1442
1443                /*
1444                 * It's safe to do this here, even though it's new data
1445                 * because all IO has been locked out of the block.
1446                 *
1447                 * mg_lock_writes() already took READ_WRITE_LOCK_LEVEL
1448                 * so _not_ using mg_upgrade_lock() as continutation.
1449                 */
1450                overwrite(mg, mg_update_metadata_after_copy);
1451
1452        } else
1453                mg_full_copy(ws);
1454}
1455
1456static int mg_lock_writes(struct dm_cache_migration *mg)
1457{
1458        int r;
1459        struct dm_cell_key_v2 key;
1460        struct cache *cache = mg->cache;
1461        struct dm_bio_prison_cell_v2 *prealloc;
1462
1463        prealloc = alloc_prison_cell(cache);
1464
1465        /*
1466         * Prevent writes to the block, but allow reads to continue.
1467         * Unless we're using an overwrite bio, in which case we lock
1468         * everything.
1469         */
1470        build_key(mg->op->oblock, oblock_succ(mg->op->oblock), &key);
1471        r = dm_cell_lock_v2(cache->prison, &key,
1472                            mg->overwrite_bio ?  READ_WRITE_LOCK_LEVEL : WRITE_LOCK_LEVEL,
1473                            prealloc, &mg->cell);
1474        if (r < 0) {
1475                free_prison_cell(cache, prealloc);
1476                mg_complete(mg, false);
1477                return r;
1478        }
1479
1480        if (mg->cell != prealloc)
1481                free_prison_cell(cache, prealloc);
1482
1483        if (r == 0)
1484                mg_copy(&mg->k.ws);
1485        else
1486                quiesce(mg, mg_copy);
1487
1488        return 0;
1489}
1490
1491static int mg_start(struct cache *cache, struct policy_work *op, struct bio *bio)
1492{
1493        struct dm_cache_migration *mg;
1494
1495        if (!background_work_begin(cache)) {
1496                policy_complete_background_work(cache->policy, op, false);
1497                return -EPERM;
1498        }
1499
1500        mg = alloc_migration(cache);
1501
1502        mg->op = op;
1503        mg->overwrite_bio = bio;
1504
1505        if (!bio)
1506                inc_io_migrations(cache);
1507
1508        return mg_lock_writes(mg);
1509}
1510
1511/*----------------------------------------------------------------
1512 * invalidation processing
1513 *--------------------------------------------------------------*/
1514
1515static void invalidate_complete(struct dm_cache_migration *mg, bool success)
1516{
1517        struct bio_list bios;
1518        struct cache *cache = mg->cache;
1519
1520        bio_list_init(&bios);
1521        if (dm_cell_unlock_v2(cache->prison, mg->cell, &bios))
1522                free_prison_cell(cache, mg->cell);
1523
1524        if (!success && mg->overwrite_bio)
1525                bio_io_error(mg->overwrite_bio);
1526
1527        free_migration(mg);
1528        defer_bios(cache, &bios);
1529
1530        background_work_end(cache);
1531}
1532
1533static void invalidate_completed(struct work_struct *ws)
1534{
1535        struct dm_cache_migration *mg = ws_to_mg(ws);
1536        invalidate_complete(mg, !mg->k.input);
1537}
1538
1539static int invalidate_cblock(struct cache *cache, dm_cblock_t cblock)
1540{
1541        int r = policy_invalidate_mapping(cache->policy, cblock);
1542        if (!r) {
1543                r = dm_cache_remove_mapping(cache->cmd, cblock);
1544                if (r) {
1545                        DMERR_LIMIT("%s: invalidation failed; couldn't update on disk metadata",
1546                                    cache_device_name(cache));
1547                        metadata_operation_failed(cache, "dm_cache_remove_mapping", r);
1548                }
1549
1550        } else if (r == -ENODATA) {
1551                /*
1552                 * Harmless, already unmapped.
1553                 */
1554                r = 0;
1555
1556        } else
1557                DMERR("%s: policy_invalidate_mapping failed", cache_device_name(cache));
1558
1559        return r;
1560}
1561
1562static void invalidate_remove(struct work_struct *ws)
1563{
1564        int r;
1565        struct dm_cache_migration *mg = ws_to_mg(ws);
1566        struct cache *cache = mg->cache;
1567
1568        r = invalidate_cblock(cache, mg->invalidate_cblock);
1569        if (r) {
1570                invalidate_complete(mg, false);
1571                return;
1572        }
1573
1574        init_continuation(&mg->k, invalidate_completed);
1575        continue_after_commit(&cache->committer, &mg->k);
1576        remap_to_origin_clear_discard(cache, mg->overwrite_bio, mg->invalidate_oblock);
1577        mg->overwrite_bio = NULL;
1578        schedule_commit(&cache->committer);
1579}
1580
1581static int invalidate_lock(struct dm_cache_migration *mg)
1582{
1583        int r;
1584        struct dm_cell_key_v2 key;
1585        struct cache *cache = mg->cache;
1586        struct dm_bio_prison_cell_v2 *prealloc;
1587
1588        prealloc = alloc_prison_cell(cache);
1589
1590        build_key(mg->invalidate_oblock, oblock_succ(mg->invalidate_oblock), &key);
1591        r = dm_cell_lock_v2(cache->prison, &key,
1592                            READ_WRITE_LOCK_LEVEL, prealloc, &mg->cell);
1593        if (r < 0) {
1594                free_prison_cell(cache, prealloc);
1595                invalidate_complete(mg, false);
1596                return r;
1597        }
1598
1599        if (mg->cell != prealloc)
1600                free_prison_cell(cache, prealloc);
1601
1602        if (r)
1603                quiesce(mg, invalidate_remove);
1604
1605        else {
1606                /*
1607                 * We can't call invalidate_remove() directly here because we
1608                 * might still be in request context.
1609                 */
1610                init_continuation(&mg->k, invalidate_remove);
1611                queue_work(cache->wq, &mg->k.ws);
1612        }
1613
1614        return 0;
1615}
1616
1617static int invalidate_start(struct cache *cache, dm_cblock_t cblock,
1618                            dm_oblock_t oblock, struct bio *bio)
1619{
1620        struct dm_cache_migration *mg;
1621
1622        if (!background_work_begin(cache))
1623                return -EPERM;
1624
1625        mg = alloc_migration(cache);
1626
1627        mg->overwrite_bio = bio;
1628        mg->invalidate_cblock = cblock;
1629        mg->invalidate_oblock = oblock;
1630
1631        return invalidate_lock(mg);
1632}
1633
1634/*----------------------------------------------------------------
1635 * bio processing
1636 *--------------------------------------------------------------*/
1637
1638enum busy {
1639        IDLE,
1640        BUSY
1641};
1642
1643static enum busy spare_migration_bandwidth(struct cache *cache)
1644{
1645        bool idle = iot_idle_for(&cache->tracker, HZ);
1646        sector_t current_volume = (atomic_read(&cache->nr_io_migrations) + 1) *
1647                cache->sectors_per_block;
1648
1649        if (idle && current_volume <= cache->migration_threshold)
1650                return IDLE;
1651        else
1652                return BUSY;
1653}
1654
1655static void inc_hit_counter(struct cache *cache, struct bio *bio)
1656{
1657        atomic_inc(bio_data_dir(bio) == READ ?
1658                   &cache->stats.read_hit : &cache->stats.write_hit);
1659}
1660
1661static void inc_miss_counter(struct cache *cache, struct bio *bio)
1662{
1663        atomic_inc(bio_data_dir(bio) == READ ?
1664                   &cache->stats.read_miss : &cache->stats.write_miss);
1665}
1666
1667/*----------------------------------------------------------------*/
1668
1669static int map_bio(struct cache *cache, struct bio *bio, dm_oblock_t block,
1670                   bool *commit_needed)
1671{
1672        int r, data_dir;
1673        bool rb, background_queued;
1674        dm_cblock_t cblock;
1675
1676        *commit_needed = false;
1677
1678        rb = bio_detain_shared(cache, block, bio);
1679        if (!rb) {
1680                /*
1681                 * An exclusive lock is held for this block, so we have to
1682                 * wait.  We set the commit_needed flag so the current
1683                 * transaction will be committed asap, allowing this lock
1684                 * to be dropped.
1685                 */
1686                *commit_needed = true;
1687                return DM_MAPIO_SUBMITTED;
1688        }
1689
1690        data_dir = bio_data_dir(bio);
1691
1692        if (optimisable_bio(cache, bio, block)) {
1693                struct policy_work *op = NULL;
1694
1695                r = policy_lookup_with_work(cache->policy, block, &cblock, data_dir, true, &op);
1696                if (unlikely(r && r != -ENOENT)) {
1697                        DMERR_LIMIT("%s: policy_lookup_with_work() failed with r = %d",
1698                                    cache_device_name(cache), r);
1699                        bio_io_error(bio);
1700                        return DM_MAPIO_SUBMITTED;
1701                }
1702
1703                if (r == -ENOENT && op) {
1704                        bio_drop_shared_lock(cache, bio);
1705                        BUG_ON(op->op != POLICY_PROMOTE);
1706                        mg_start(cache, op, bio);
1707                        return DM_MAPIO_SUBMITTED;
1708                }
1709        } else {
1710                r = policy_lookup(cache->policy, block, &cblock, data_dir, false, &background_queued);
1711                if (unlikely(r && r != -ENOENT)) {
1712                        DMERR_LIMIT("%s: policy_lookup() failed with r = %d",
1713                                    cache_device_name(cache), r);
1714                        bio_io_error(bio);
1715                        return DM_MAPIO_SUBMITTED;
1716                }
1717
1718                if (background_queued)
1719                        wake_migration_worker(cache);
1720        }
1721
1722        if (r == -ENOENT) {
1723                struct per_bio_data *pb = get_per_bio_data(bio);
1724
1725                /*
1726                 * Miss.
1727                 */
1728                inc_miss_counter(cache, bio);
1729                if (pb->req_nr == 0) {
1730                        accounted_begin(cache, bio);
1731                        remap_to_origin_clear_discard(cache, bio, block);
1732                } else {
1733                        /*
1734                         * This is a duplicate writethrough io that is no
1735                         * longer needed because the block has been demoted.
1736                         */
1737                        bio_endio(bio);
1738                        return DM_MAPIO_SUBMITTED;
1739                }
1740        } else {
1741                /*
1742                 * Hit.
1743                 */
1744                inc_hit_counter(cache, bio);
1745
1746                /*
1747                 * Passthrough always maps to the origin, invalidating any
1748                 * cache blocks that are written to.
1749                 */
1750                if (passthrough_mode(cache)) {
1751                        if (bio_data_dir(bio) == WRITE) {
1752                                bio_drop_shared_lock(cache, bio);
1753                                atomic_inc(&cache->stats.demotion);
1754                                invalidate_start(cache, cblock, block, bio);
1755                        } else
1756                                remap_to_origin_clear_discard(cache, bio, block);
1757                } else {
1758                        if (bio_data_dir(bio) == WRITE && writethrough_mode(cache) &&
1759                            !is_dirty(cache, cblock)) {
1760                                remap_to_origin_and_cache(cache, bio, block, cblock);
1761                                accounted_begin(cache, bio);
1762                        } else
1763                                remap_to_cache_dirty(cache, bio, block, cblock);
1764                }
1765        }
1766
1767        /*
1768         * dm core turns FUA requests into a separate payload and FLUSH req.
1769         */
1770        if (bio->bi_opf & REQ_FUA) {
1771                /*
1772                 * issue_after_commit will call accounted_begin a second time.  So
1773                 * we call accounted_complete() to avoid double accounting.
1774                 */
1775                accounted_complete(cache, bio);
1776                issue_after_commit(&cache->committer, bio);
1777                *commit_needed = true;
1778                return DM_MAPIO_SUBMITTED;
1779        }
1780
1781        return DM_MAPIO_REMAPPED;
1782}
1783
1784static bool process_bio(struct cache *cache, struct bio *bio)
1785{
1786        bool commit_needed;
1787
1788        if (map_bio(cache, bio, get_bio_block(cache, bio), &commit_needed) == DM_MAPIO_REMAPPED)
1789                submit_bio_noacct(bio);
1790
1791        return commit_needed;
1792}
1793
1794/*
1795 * A non-zero return indicates read_only or fail_io mode.
1796 */
1797static int commit(struct cache *cache, bool clean_shutdown)
1798{
1799        int r;
1800
1801        if (get_cache_mode(cache) >= CM_READ_ONLY)
1802                return -EINVAL;
1803
1804        atomic_inc(&cache->stats.commit_count);
1805        r = dm_cache_commit(cache->cmd, clean_shutdown);
1806        if (r)
1807                metadata_operation_failed(cache, "dm_cache_commit", r);
1808
1809        return r;
1810}
1811
1812/*
1813 * Used by the batcher.
1814 */
1815static blk_status_t commit_op(void *context)
1816{
1817        struct cache *cache = context;
1818
1819        if (dm_cache_changed_this_transaction(cache->cmd))
1820                return errno_to_blk_status(commit(cache, false));
1821
1822        return 0;
1823}
1824
1825/*----------------------------------------------------------------*/
1826
1827static bool process_flush_bio(struct cache *cache, struct bio *bio)
1828{
1829        struct per_bio_data *pb = get_per_bio_data(bio);
1830
1831        if (!pb->req_nr)
1832                remap_to_origin(cache, bio);
1833        else
1834                remap_to_cache(cache, bio, 0);
1835
1836        issue_after_commit(&cache->committer, bio);
1837        return true;
1838}
1839
1840static bool process_discard_bio(struct cache *cache, struct bio *bio)
1841{
1842        dm_dblock_t b, e;
1843
1844        // FIXME: do we need to lock the region?  Or can we just assume the
1845        // user wont be so foolish as to issue discard concurrently with
1846        // other IO?
1847        calc_discard_block_range(cache, bio, &b, &e);
1848        while (b != e) {
1849                set_discard(cache, b);
1850                b = to_dblock(from_dblock(b) + 1);
1851        }
1852
1853        if (cache->features.discard_passdown) {
1854                remap_to_origin(cache, bio);
1855                submit_bio_noacct(bio);
1856        } else
1857                bio_endio(bio);
1858
1859        return false;
1860}
1861
1862static void process_deferred_bios(struct work_struct *ws)
1863{
1864        struct cache *cache = container_of(ws, struct cache, deferred_bio_worker);
1865
1866        bool commit_needed = false;
1867        struct bio_list bios;
1868        struct bio *bio;
1869
1870        bio_list_init(&bios);
1871
1872        spin_lock_irq(&cache->lock);
1873        bio_list_merge(&bios, &cache->deferred_bios);
1874        bio_list_init(&cache->deferred_bios);
1875        spin_unlock_irq(&cache->lock);
1876
1877        while ((bio = bio_list_pop(&bios))) {
1878                if (bio->bi_opf & REQ_PREFLUSH)
1879                        commit_needed = process_flush_bio(cache, bio) || commit_needed;
1880
1881                else if (bio_op(bio) == REQ_OP_DISCARD)
1882                        commit_needed = process_discard_bio(cache, bio) || commit_needed;
1883
1884                else
1885                        commit_needed = process_bio(cache, bio) || commit_needed;
1886        }
1887
1888        if (commit_needed)
1889                schedule_commit(&cache->committer);
1890}
1891
1892/*----------------------------------------------------------------
1893 * Main worker loop
1894 *--------------------------------------------------------------*/
1895
1896static void requeue_deferred_bios(struct cache *cache)
1897{
1898        struct bio *bio;
1899        struct bio_list bios;
1900
1901        bio_list_init(&bios);
1902        bio_list_merge(&bios, &cache->deferred_bios);
1903        bio_list_init(&cache->deferred_bios);
1904
1905        while ((bio = bio_list_pop(&bios))) {
1906                bio->bi_status = BLK_STS_DM_REQUEUE;
1907                bio_endio(bio);
1908        }
1909}
1910
1911/*
1912 * We want to commit periodically so that not too much
1913 * unwritten metadata builds up.
1914 */
1915static void do_waker(struct work_struct *ws)
1916{
1917        struct cache *cache = container_of(to_delayed_work(ws), struct cache, waker);
1918
1919        policy_tick(cache->policy, true);
1920        wake_migration_worker(cache);
1921        schedule_commit(&cache->committer);
1922        queue_delayed_work(cache->wq, &cache->waker, COMMIT_PERIOD);
1923}
1924
1925static void check_migrations(struct work_struct *ws)
1926{
1927        int r;
1928        struct policy_work *op;
1929        struct cache *cache = container_of(ws, struct cache, migration_worker);
1930        enum busy b;
1931
1932        for (;;) {
1933                b = spare_migration_bandwidth(cache);
1934
1935                r = policy_get_background_work(cache->policy, b == IDLE, &op);
1936                if (r == -ENODATA)
1937                        break;
1938
1939                if (r) {
1940                        DMERR_LIMIT("%s: policy_background_work failed",
1941                                    cache_device_name(cache));
1942                        break;
1943                }
1944
1945                r = mg_start(cache, op, NULL);
1946                if (r)
1947                        break;
1948        }
1949}
1950
1951/*----------------------------------------------------------------
1952 * Target methods
1953 *--------------------------------------------------------------*/
1954
1955/*
1956 * This function gets called on the error paths of the constructor, so we
1957 * have to cope with a partially initialised struct.
1958 */
1959static void destroy(struct cache *cache)
1960{
1961        unsigned i;
1962
1963        mempool_exit(&cache->migration_pool);
1964
1965        if (cache->prison)
1966                dm_bio_prison_destroy_v2(cache->prison);
1967
1968        if (cache->wq)
1969                destroy_workqueue(cache->wq);
1970
1971        if (cache->dirty_bitset)
1972                free_bitset(cache->dirty_bitset);
1973
1974        if (cache->discard_bitset)
1975                free_bitset(cache->discard_bitset);
1976
1977        if (cache->copier)
1978                dm_kcopyd_client_destroy(cache->copier);
1979
1980        if (cache->cmd)
1981                dm_cache_metadata_close(cache->cmd);
1982
1983        if (cache->metadata_dev)
1984                dm_put_device(cache->ti, cache->metadata_dev);
1985
1986        if (cache->origin_dev)
1987                dm_put_device(cache->ti, cache->origin_dev);
1988
1989        if (cache->cache_dev)
1990                dm_put_device(cache->ti, cache->cache_dev);
1991
1992        if (cache->policy)
1993                dm_cache_policy_destroy(cache->policy);
1994
1995        for (i = 0; i < cache->nr_ctr_args ; i++)
1996                kfree(cache->ctr_args[i]);
1997        kfree(cache->ctr_args);
1998
1999        bioset_exit(&cache->bs);
2000
2001        kfree(cache);
2002}
2003
2004static void cache_dtr(struct dm_target *ti)
2005{
2006        struct cache *cache = ti->private;
2007
2008        destroy(cache);
2009}
2010
2011static sector_t get_dev_size(struct dm_dev *dev)
2012{
2013        return i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT;
2014}
2015
2016/*----------------------------------------------------------------*/
2017
2018/*
2019 * Construct a cache device mapping.
2020 *
2021 * cache <metadata dev> <cache dev> <origin dev> <block size>
2022 *       <#feature args> [<feature arg>]*
2023 *       <policy> <#policy args> [<policy arg>]*
2024 *
2025 * metadata dev    : fast device holding the persistent metadata
2026 * cache dev       : fast device holding cached data blocks
2027 * origin dev      : slow device holding original data blocks
2028 * block size      : cache unit size in sectors
2029 *
2030 * #feature args   : number of feature arguments passed
2031 * feature args    : writethrough.  (The default is writeback.)
2032 *
2033 * policy          : the replacement policy to use
2034 * #policy args    : an even number of policy arguments corresponding
2035 *                   to key/value pairs passed to the policy
2036 * policy args     : key/value pairs passed to the policy
2037 *                   E.g. 'sequential_threshold 1024'
2038 *                   See cache-policies.txt for details.
2039 *
2040 * Optional feature arguments are:
2041 *   writethrough  : write through caching that prohibits cache block
2042 *                   content from being different from origin block content.
2043 *                   Without this argument, the default behaviour is to write
2044 *                   back cache block contents later for performance reasons,
2045 *                   so they may differ from the corresponding origin blocks.
2046 */
2047struct cache_args {
2048        struct dm_target *ti;
2049
2050        struct dm_dev *metadata_dev;
2051
2052        struct dm_dev *cache_dev;
2053        sector_t cache_sectors;
2054
2055        struct dm_dev *origin_dev;
2056        sector_t origin_sectors;
2057
2058        uint32_t block_size;
2059
2060        const char *policy_name;
2061        int policy_argc;
2062        const char **policy_argv;
2063
2064        struct cache_features features;
2065};
2066
2067static void destroy_cache_args(struct cache_args *ca)
2068{
2069        if (ca->metadata_dev)
2070                dm_put_device(ca->ti, ca->metadata_dev);
2071
2072        if (ca->cache_dev)
2073                dm_put_device(ca->ti, ca->cache_dev);
2074
2075        if (ca->origin_dev)
2076                dm_put_device(ca->ti, ca->origin_dev);
2077
2078        kfree(ca);
2079}
2080
2081static bool at_least_one_arg(struct dm_arg_set *as, char **error)
2082{
2083        if (!as->argc) {
2084                *error = "Insufficient args";
2085                return false;
2086        }
2087
2088        return true;
2089}
2090
2091static int parse_metadata_dev(struct cache_args *ca, struct dm_arg_set *as,
2092                              char **error)
2093{
2094        int r;
2095        sector_t metadata_dev_size;
2096        char b[BDEVNAME_SIZE];
2097
2098        if (!at_least_one_arg(as, error))
2099                return -EINVAL;
2100
2101        r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
2102                          &ca->metadata_dev);
2103        if (r) {
2104                *error = "Error opening metadata device";
2105                return r;
2106        }
2107
2108        metadata_dev_size = get_dev_size(ca->metadata_dev);
2109        if (metadata_dev_size > DM_CACHE_METADATA_MAX_SECTORS_WARNING)
2110                DMWARN("Metadata device %s is larger than %u sectors: excess space will not be used.",
2111                       bdevname(ca->metadata_dev->bdev, b), THIN_METADATA_MAX_SECTORS);
2112
2113        return 0;
2114}
2115
2116static int parse_cache_dev(struct cache_args *ca, struct dm_arg_set *as,
2117                           char **error)
2118{
2119        int r;
2120
2121        if (!at_least_one_arg(as, error))
2122                return -EINVAL;
2123
2124        r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
2125                          &ca->cache_dev);
2126        if (r) {
2127                *error = "Error opening cache device";
2128                return r;
2129        }
2130        ca->cache_sectors = get_dev_size(ca->cache_dev);
2131
2132        return 0;
2133}
2134
2135static int parse_origin_dev(struct cache_args *ca, struct dm_arg_set *as,
2136                            char **error)
2137{
2138        int r;
2139
2140        if (!at_least_one_arg(as, error))
2141                return -EINVAL;
2142
2143        r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
2144                          &ca->origin_dev);
2145        if (r) {
2146                *error = "Error opening origin device";
2147                return r;
2148        }
2149
2150        ca->origin_sectors = get_dev_size(ca->origin_dev);
2151        if (ca->ti->len > ca->origin_sectors) {
2152                *error = "Device size larger than cached device";
2153                return -EINVAL;
2154        }
2155
2156        return 0;
2157}
2158
2159static int parse_block_size(struct cache_args *ca, struct dm_arg_set *as,
2160                            char **error)
2161{
2162        unsigned long block_size;
2163
2164        if (!at_least_one_arg(as, error))
2165                return -EINVAL;
2166
2167        if (kstrtoul(dm_shift_arg(as), 10, &block_size) || !block_size ||
2168            block_size < DATA_DEV_BLOCK_SIZE_MIN_SECTORS ||
2169            block_size > DATA_DEV_BLOCK_SIZE_MAX_SECTORS ||
2170            block_size & (DATA_DEV_BLOCK_SIZE_MIN_SECTORS - 1)) {
2171                *error = "Invalid data block size";
2172                return -EINVAL;
2173        }
2174
2175        if (block_size > ca->cache_sectors) {
2176                *error = "Data block size is larger than the cache device";
2177                return -EINVAL;
2178        }
2179
2180        ca->block_size = block_size;
2181
2182        return 0;
2183}
2184
2185static void init_features(struct cache_features *cf)
2186{
2187        cf->mode = CM_WRITE;
2188        cf->io_mode = CM_IO_WRITEBACK;
2189        cf->metadata_version = 1;
2190        cf->discard_passdown = true;
2191}
2192
2193static int parse_features(struct cache_args *ca, struct dm_arg_set *as,
2194                          char **error)
2195{
2196        static const struct dm_arg _args[] = {
2197                {0, 3, "Invalid number of cache feature arguments"},
2198        };
2199
2200        int r, mode_ctr = 0;
2201        unsigned argc;
2202        const char *arg;
2203        struct cache_features *cf = &ca->features;
2204
2205        init_features(cf);
2206
2207        r = dm_read_arg_group(_args, as, &argc, error);
2208        if (r)
2209                return -EINVAL;
2210
2211        while (argc--) {
2212                arg = dm_shift_arg(as);
2213
2214                if (!strcasecmp(arg, "writeback")) {
2215                        cf->io_mode = CM_IO_WRITEBACK;
2216                        mode_ctr++;
2217                }
2218
2219                else if (!strcasecmp(arg, "writethrough")) {
2220                        cf->io_mode = CM_IO_WRITETHROUGH;
2221                        mode_ctr++;
2222                }
2223
2224                else if (!strcasecmp(arg, "passthrough")) {
2225                        cf->io_mode = CM_IO_PASSTHROUGH;
2226                        mode_ctr++;
2227                }
2228
2229                else if (!strcasecmp(arg, "metadata2"))
2230                        cf->metadata_version = 2;
2231
2232                else if (!strcasecmp(arg, "no_discard_passdown"))
2233                        cf->discard_passdown = false;
2234
2235                else {
2236                        *error = "Unrecognised cache feature requested";
2237                        return -EINVAL;
2238                }
2239        }
2240
2241        if (mode_ctr > 1) {
2242                *error = "Duplicate cache io_mode features requested";
2243                return -EINVAL;
2244        }
2245
2246        return 0;
2247}
2248
2249static int parse_policy(struct cache_args *ca, struct dm_arg_set *as,
2250                        char **error)
2251{
2252        static const struct dm_arg _args[] = {
2253                {0, 1024, "Invalid number of policy arguments"},
2254        };
2255
2256        int r;
2257
2258        if (!at_least_one_arg(as, error))
2259                return -EINVAL;
2260
2261        ca->policy_name = dm_shift_arg(as);
2262
2263        r = dm_read_arg_group(_args, as, &ca->policy_argc, error);
2264        if (r)
2265                return -EINVAL;
2266
2267        ca->policy_argv = (const char **)as->argv;
2268        dm_consume_args(as, ca->policy_argc);
2269
2270        return 0;
2271}
2272
2273static int parse_cache_args(struct cache_args *ca, int argc, char **argv,
2274                            char **error)
2275{
2276        int r;
2277        struct dm_arg_set as;
2278
2279        as.argc = argc;
2280        as.argv = argv;
2281
2282        r = parse_metadata_dev(ca, &as, error);
2283        if (r)
2284                return r;
2285
2286        r = parse_cache_dev(ca, &as, error);
2287        if (r)
2288                return r;
2289
2290        r = parse_origin_dev(ca, &as, error);
2291        if (r)
2292                return r;
2293
2294        r = parse_block_size(ca, &as, error);
2295        if (r)
2296                return r;
2297
2298        r = parse_features(ca, &as, error);
2299        if (r)
2300                return r;
2301
2302        r = parse_policy(ca, &as, error);
2303        if (r)
2304                return r;
2305
2306        return 0;
2307}
2308
2309/*----------------------------------------------------------------*/
2310
2311static struct kmem_cache *migration_cache;
2312
2313#define NOT_CORE_OPTION 1
2314
2315static int process_config_option(struct cache *cache, const char *key, const char *value)
2316{
2317        unsigned long tmp;
2318
2319        if (!strcasecmp(key, "migration_threshold")) {
2320                if (kstrtoul(value, 10, &tmp))
2321                        return -EINVAL;
2322
2323                cache->migration_threshold = tmp;
2324                return 0;
2325        }
2326
2327        return NOT_CORE_OPTION;
2328}
2329
2330static int set_config_value(struct cache *cache, const char *key, const char *value)
2331{
2332        int r = process_config_option(cache, key, value);
2333
2334        if (r == NOT_CORE_OPTION)
2335                r = policy_set_config_value(cache->policy, key, value);
2336
2337        if (r)
2338                DMWARN("bad config value for %s: %s", key, value);
2339
2340        return r;
2341}
2342
2343static int set_config_values(struct cache *cache, int argc, const char **argv)
2344{
2345        int r = 0;
2346
2347        if (argc & 1) {
2348                DMWARN("Odd number of policy arguments given but they should be <key> <value> pairs.");
2349                return -EINVAL;
2350        }
2351
2352        while (argc) {
2353                r = set_config_value(cache, argv[0], argv[1]);
2354                if (r)
2355                        break;
2356
2357                argc -= 2;
2358                argv += 2;
2359        }
2360
2361        return r;
2362}
2363
2364static int create_cache_policy(struct cache *cache, struct cache_args *ca,
2365                               char **error)
2366{
2367        struct dm_cache_policy *p = dm_cache_policy_create(ca->policy_name,
2368                                                           cache->cache_size,
2369                                                           cache->origin_sectors,
2370                                                           cache->sectors_per_block);
2371        if (IS_ERR(p)) {
2372                *error = "Error creating cache's policy";
2373                return PTR_ERR(p);
2374        }
2375        cache->policy = p;
2376        BUG_ON(!cache->policy);
2377
2378        return 0;
2379}
2380
2381/*
2382 * We want the discard block size to be at least the size of the cache
2383 * block size and have no more than 2^14 discard blocks across the origin.
2384 */
2385#define MAX_DISCARD_BLOCKS (1 << 14)
2386
2387static bool too_many_discard_blocks(sector_t discard_block_size,
2388                                    sector_t origin_size)
2389{
2390        (void) sector_div(origin_size, discard_block_size);
2391
2392        return origin_size > MAX_DISCARD_BLOCKS;
2393}
2394
2395static sector_t calculate_discard_block_size(sector_t cache_block_size,
2396                                             sector_t origin_size)
2397{
2398        sector_t discard_block_size = cache_block_size;
2399
2400        if (origin_size)
2401                while (too_many_discard_blocks(discard_block_size, origin_size))
2402                        discard_block_size *= 2;
2403
2404        return discard_block_size;
2405}
2406
2407static void set_cache_size(struct cache *cache, dm_cblock_t size)
2408{
2409        dm_block_t nr_blocks = from_cblock(size);
2410
2411        if (nr_blocks > (1 << 20) && cache->cache_size != size)
2412                DMWARN_LIMIT("You have created a cache device with a lot of individual cache blocks (%llu)\n"
2413                             "All these mappings can consume a lot of kernel memory, and take some time to read/write.\n"
2414                             "Please consider increasing the cache block size to reduce the overall cache block count.",
2415                             (unsigned long long) nr_blocks);
2416
2417        cache->cache_size = size;
2418}
2419
2420#define DEFAULT_MIGRATION_THRESHOLD 2048
2421
2422static int cache_create(struct cache_args *ca, struct cache **result)
2423{
2424        int r = 0;
2425        char **error = &ca->ti->error;
2426        struct cache *cache;
2427        struct dm_target *ti = ca->ti;
2428        dm_block_t origin_blocks;
2429        struct dm_cache_metadata *cmd;
2430        bool may_format = ca->features.mode == CM_WRITE;
2431
2432        cache = kzalloc(sizeof(*cache), GFP_KERNEL);
2433        if (!cache)
2434                return -ENOMEM;
2435
2436        cache->ti = ca->ti;
2437        ti->private = cache;
2438        ti->num_flush_bios = 2;
2439        ti->flush_supported = true;
2440
2441        ti->num_discard_bios = 1;
2442        ti->discards_supported = true;
2443
2444        ti->per_io_data_size = sizeof(struct per_bio_data);
2445
2446        cache->features = ca->features;
2447        if (writethrough_mode(cache)) {
2448                /* Create bioset for writethrough bios issued to origin */
2449                r = bioset_init(&cache->bs, BIO_POOL_SIZE, 0, 0);
2450                if (r)
2451                        goto bad;
2452        }
2453
2454        cache->metadata_dev = ca->metadata_dev;
2455        cache->origin_dev = ca->origin_dev;
2456        cache->cache_dev = ca->cache_dev;
2457
2458        ca->metadata_dev = ca->origin_dev = ca->cache_dev = NULL;
2459
2460        origin_blocks = cache->origin_sectors = ca->origin_sectors;
2461        origin_blocks = block_div(origin_blocks, ca->block_size);
2462        cache->origin_blocks = to_oblock(origin_blocks);
2463
2464        cache->sectors_per_block = ca->block_size;
2465        if (dm_set_target_max_io_len(ti, cache->sectors_per_block)) {
2466                r = -EINVAL;
2467                goto bad;
2468        }
2469
2470        if (ca->block_size & (ca->block_size - 1)) {
2471                dm_block_t cache_size = ca->cache_sectors;
2472
2473                cache->sectors_per_block_shift = -1;
2474                cache_size = block_div(cache_size, ca->block_size);
2475                set_cache_size(cache, to_cblock(cache_size));
2476        } else {
2477                cache->sectors_per_block_shift = __ffs(ca->block_size);
2478                set_cache_size(cache, to_cblock(ca->cache_sectors >> cache->sectors_per_block_shift));
2479        }
2480
2481        r = create_cache_policy(cache, ca, error);
2482        if (r)
2483                goto bad;
2484
2485        cache->policy_nr_args = ca->policy_argc;
2486        cache->migration_threshold = DEFAULT_MIGRATION_THRESHOLD;
2487
2488        r = set_config_values(cache, ca->policy_argc, ca->policy_argv);
2489        if (r) {
2490                *error = "Error setting cache policy's config values";
2491                goto bad;
2492        }
2493
2494        cmd = dm_cache_metadata_open(cache->metadata_dev->bdev,
2495                                     ca->block_size, may_format,
2496                                     dm_cache_policy_get_hint_size(cache->policy),
2497                                     ca->features.metadata_version);
2498        if (IS_ERR(cmd)) {
2499                *error = "Error creating metadata object";
2500                r = PTR_ERR(cmd);
2501                goto bad;
2502        }
2503        cache->cmd = cmd;
2504        set_cache_mode(cache, CM_WRITE);
2505        if (get_cache_mode(cache) != CM_WRITE) {
2506                *error = "Unable to get write access to metadata, please check/repair metadata.";
2507                r = -EINVAL;
2508                goto bad;
2509        }
2510
2511        if (passthrough_mode(cache)) {
2512                bool all_clean;
2513
2514                r = dm_cache_metadata_all_clean(cache->cmd, &all_clean);
2515                if (r) {
2516                        *error = "dm_cache_metadata_all_clean() failed";
2517                        goto bad;
2518                }
2519
2520                if (!all_clean) {
2521                        *error = "Cannot enter passthrough mode unless all blocks are clean";
2522                        r = -EINVAL;
2523                        goto bad;
2524                }
2525
2526                policy_allow_migrations(cache->policy, false);
2527        }
2528
2529        spin_lock_init(&cache->lock);
2530        bio_list_init(&cache->deferred_bios);
2531        atomic_set(&cache->nr_allocated_migrations, 0);
2532        atomic_set(&cache->nr_io_migrations, 0);
2533        init_waitqueue_head(&cache->migration_wait);
2534
2535        r = -ENOMEM;
2536        atomic_set(&cache->nr_dirty, 0);
2537        cache->dirty_bitset = alloc_bitset(from_cblock(cache->cache_size));
2538        if (!cache->dirty_bitset) {
2539                *error = "could not allocate dirty bitset";
2540                goto bad;
2541        }
2542        clear_bitset(cache->dirty_bitset, from_cblock(cache->cache_size));
2543
2544        cache->discard_block_size =
2545                calculate_discard_block_size(cache->sectors_per_block,
2546                                             cache->origin_sectors);
2547        cache->discard_nr_blocks = to_dblock(dm_sector_div_up(cache->origin_sectors,
2548                                                              cache->discard_block_size));
2549        cache->discard_bitset = alloc_bitset(from_dblock(cache->discard_nr_blocks));
2550        if (!cache->discard_bitset) {
2551                *error = "could not allocate discard bitset";
2552                goto bad;
2553        }
2554        clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks));
2555
2556        cache->copier = dm_kcopyd_client_create(&dm_kcopyd_throttle);
2557        if (IS_ERR(cache->copier)) {
2558                *error = "could not create kcopyd client";
2559                r = PTR_ERR(cache->copier);
2560                goto bad;
2561        }
2562
2563        cache->wq = alloc_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM, 0);
2564        if (!cache->wq) {
2565                *error = "could not create workqueue for metadata object";
2566                goto bad;
2567        }
2568        INIT_WORK(&cache->deferred_bio_worker, process_deferred_bios);
2569        INIT_WORK(&cache->migration_worker, check_migrations);
2570        INIT_DELAYED_WORK(&cache->waker, do_waker);
2571
2572        cache->prison = dm_bio_prison_create_v2(cache->wq);
2573        if (!cache->prison) {
2574                *error = "could not create bio prison";
2575                goto bad;
2576        }
2577
2578        r = mempool_init_slab_pool(&cache->migration_pool, MIGRATION_POOL_SIZE,
2579                                   migration_cache);
2580        if (r) {
2581                *error = "Error creating cache's migration mempool";
2582                goto bad;
2583        }
2584
2585        cache->need_tick_bio = true;
2586        cache->sized = false;
2587        cache->invalidate = false;
2588        cache->commit_requested = false;
2589        cache->loaded_mappings = false;
2590        cache->loaded_discards = false;
2591
2592        load_stats(cache);
2593
2594        atomic_set(&cache->stats.demotion, 0);
2595        atomic_set(&cache->stats.promotion, 0);
2596        atomic_set(&cache->stats.copies_avoided, 0);
2597        atomic_set(&cache->stats.cache_cell_clash, 0);
2598        atomic_set(&cache->stats.commit_count, 0);
2599        atomic_set(&cache->stats.discard_count, 0);
2600
2601        spin_lock_init(&cache->invalidation_lock);
2602        INIT_LIST_HEAD(&cache->invalidation_requests);
2603
2604        batcher_init(&cache->committer, commit_op, cache,
2605                     issue_op, cache, cache->wq);
2606        iot_init(&cache->tracker);
2607
2608        init_rwsem(&cache->background_work_lock);
2609        prevent_background_work(cache);
2610
2611        *result = cache;
2612        return 0;
2613bad:
2614        destroy(cache);
2615        return r;
2616}
2617
2618static int copy_ctr_args(struct cache *cache, int argc, const char **argv)
2619{
2620        unsigned i;
2621        const char **copy;
2622
2623        copy = kcalloc(argc, sizeof(*copy), GFP_KERNEL);
2624        if (!copy)
2625                return -ENOMEM;
2626        for (i = 0; i < argc; i++) {
2627                copy[i] = kstrdup(argv[i], GFP_KERNEL);
2628                if (!copy[i]) {
2629                        while (i--)
2630                                kfree(copy[i]);
2631                        kfree(copy);
2632                        return -ENOMEM;
2633                }
2634        }
2635
2636        cache->nr_ctr_args = argc;
2637        cache->ctr_args = copy;
2638
2639        return 0;
2640}
2641
2642static int cache_ctr(struct dm_target *ti, unsigned argc, char **argv)
2643{
2644        int r = -EINVAL;
2645        struct cache_args *ca;
2646        struct cache *cache = NULL;
2647
2648        ca = kzalloc(sizeof(*ca), GFP_KERNEL);
2649        if (!ca) {
2650                ti->error = "Error allocating memory for cache";
2651                return -ENOMEM;
2652        }
2653        ca->ti = ti;
2654
2655        r = parse_cache_args(ca, argc, argv, &ti->error);
2656        if (r)
2657                goto out;
2658
2659        r = cache_create(ca, &cache);
2660        if (r)
2661                goto out;
2662
2663        r = copy_ctr_args(cache, argc - 3, (const char **)argv + 3);
2664        if (r) {
2665                destroy(cache);
2666                goto out;
2667        }
2668
2669        ti->private = cache;
2670out:
2671        destroy_cache_args(ca);
2672        return r;
2673}
2674
2675/*----------------------------------------------------------------*/
2676
2677static int cache_map(struct dm_target *ti, struct bio *bio)
2678{
2679        struct cache *cache = ti->private;
2680
2681        int r;
2682        bool commit_needed;
2683        dm_oblock_t block = get_bio_block(cache, bio);
2684
2685        init_per_bio_data(bio);
2686        if (unlikely(from_oblock(block) >= from_oblock(cache->origin_blocks))) {
2687                /*
2688                 * This can only occur if the io goes to a partial block at
2689                 * the end of the origin device.  We don't cache these.
2690                 * Just remap to the origin and carry on.
2691                 */
2692                remap_to_origin(cache, bio);
2693                accounted_begin(cache, bio);
2694                return DM_MAPIO_REMAPPED;
2695        }
2696
2697        if (discard_or_flush(bio)) {
2698                defer_bio(cache, bio);
2699                return DM_MAPIO_SUBMITTED;
2700        }
2701
2702        r = map_bio(cache, bio, block, &commit_needed);
2703        if (commit_needed)
2704                schedule_commit(&cache->committer);
2705
2706        return r;
2707}
2708
2709static int cache_end_io(struct dm_target *ti, struct bio *bio, blk_status_t *error)
2710{
2711        struct cache *cache = ti->private;
2712        unsigned long flags;
2713        struct per_bio_data *pb = get_per_bio_data(bio);
2714
2715        if (pb->tick) {
2716                policy_tick(cache->policy, false);
2717
2718                spin_lock_irqsave(&cache->lock, flags);
2719                cache->need_tick_bio = true;
2720                spin_unlock_irqrestore(&cache->lock, flags);
2721        }
2722
2723        bio_drop_shared_lock(cache, bio);
2724        accounted_complete(cache, bio);
2725
2726        return DM_ENDIO_DONE;
2727}
2728
2729static int write_dirty_bitset(struct cache *cache)
2730{
2731        int r;
2732
2733        if (get_cache_mode(cache) >= CM_READ_ONLY)
2734                return -EINVAL;
2735
2736        r = dm_cache_set_dirty_bits(cache->cmd, from_cblock(cache->cache_size), cache->dirty_bitset);
2737        if (r)
2738                metadata_operation_failed(cache, "dm_cache_set_dirty_bits", r);
2739
2740        return r;
2741}
2742
2743static int write_discard_bitset(struct cache *cache)
2744{
2745        unsigned i, r;
2746
2747        if (get_cache_mode(cache) >= CM_READ_ONLY)
2748                return -EINVAL;
2749
2750        r = dm_cache_discard_bitset_resize(cache->cmd, cache->discard_block_size,
2751                                           cache->discard_nr_blocks);
2752        if (r) {
2753                DMERR("%s: could not resize on-disk discard bitset", cache_device_name(cache));
2754                metadata_operation_failed(cache, "dm_cache_discard_bitset_resize", r);
2755                return r;
2756        }
2757
2758        for (i = 0; i < from_dblock(cache->discard_nr_blocks); i++) {
2759                r = dm_cache_set_discard(cache->cmd, to_dblock(i),
2760                                         is_discarded(cache, to_dblock(i)));
2761                if (r) {
2762                        metadata_operation_failed(cache, "dm_cache_set_discard", r);
2763                        return r;
2764                }
2765        }
2766
2767        return 0;
2768}
2769
2770static int write_hints(struct cache *cache)
2771{
2772        int r;
2773
2774        if (get_cache_mode(cache) >= CM_READ_ONLY)
2775                return -EINVAL;
2776
2777        r = dm_cache_write_hints(cache->cmd, cache->policy);
2778        if (r) {
2779                metadata_operation_failed(cache, "dm_cache_write_hints", r);
2780                return r;
2781        }
2782
2783        return 0;
2784}
2785
2786/*
2787 * returns true on success
2788 */
2789static bool sync_metadata(struct cache *cache)
2790{
2791        int r1, r2, r3, r4;
2792
2793        r1 = write_dirty_bitset(cache);
2794        if (r1)
2795                DMERR("%s: could not write dirty bitset", cache_device_name(cache));
2796
2797        r2 = write_discard_bitset(cache);
2798        if (r2)
2799                DMERR("%s: could not write discard bitset", cache_device_name(cache));
2800
2801        save_stats(cache);
2802
2803        r3 = write_hints(cache);
2804        if (r3)
2805                DMERR("%s: could not write hints", cache_device_name(cache));
2806
2807        /*
2808         * If writing the above metadata failed, we still commit, but don't
2809         * set the clean shutdown flag.  This will effectively force every
2810         * dirty bit to be set on reload.
2811         */
2812        r4 = commit(cache, !r1 && !r2 && !r3);
2813        if (r4)
2814                DMERR("%s: could not write cache metadata", cache_device_name(cache));
2815
2816        return !r1 && !r2 && !r3 && !r4;
2817}
2818
2819static void cache_postsuspend(struct dm_target *ti)
2820{
2821        struct cache *cache = ti->private;
2822
2823        prevent_background_work(cache);
2824        BUG_ON(atomic_read(&cache->nr_io_migrations));
2825
2826        cancel_delayed_work_sync(&cache->waker);
2827        drain_workqueue(cache->wq);
2828        WARN_ON(cache->tracker.in_flight);
2829
2830        /*
2831         * If it's a flush suspend there won't be any deferred bios, so this
2832         * call is harmless.
2833         */
2834        requeue_deferred_bios(cache);
2835
2836        if (get_cache_mode(cache) == CM_WRITE)
2837                (void) sync_metadata(cache);
2838}
2839
2840static int load_mapping(void *context, dm_oblock_t oblock, dm_cblock_t cblock,
2841                        bool dirty, uint32_t hint, bool hint_valid)
2842{
2843        struct cache *cache = context;
2844
2845        if (dirty) {
2846                set_bit(from_cblock(cblock), cache->dirty_bitset);
2847                atomic_inc(&cache->nr_dirty);
2848        } else
2849                clear_bit(from_cblock(cblock), cache->dirty_bitset);
2850
2851        return policy_load_mapping(cache->policy, oblock, cblock, dirty, hint, hint_valid);
2852}
2853
2854/*
2855 * The discard block size in the on disk metadata is not
2856 * neccessarily the same as we're currently using.  So we have to
2857 * be careful to only set the discarded attribute if we know it
2858 * covers a complete block of the new size.
2859 */
2860struct discard_load_info {
2861        struct cache *cache;
2862
2863        /*
2864         * These blocks are sized using the on disk dblock size, rather
2865         * than the current one.
2866         */
2867        dm_block_t block_size;
2868        dm_block_t discard_begin, discard_end;
2869};
2870
2871static void discard_load_info_init(struct cache *cache,
2872                                   struct discard_load_info *li)
2873{
2874        li->cache = cache;
2875        li->discard_begin = li->discard_end = 0;
2876}
2877
2878static void set_discard_range(struct discard_load_info *li)
2879{
2880        sector_t b, e;
2881
2882        if (li->discard_begin == li->discard_end)
2883                return;
2884
2885        /*
2886         * Convert to sectors.
2887         */
2888        b = li->discard_begin * li->block_size;
2889        e = li->discard_end * li->block_size;
2890
2891        /*
2892         * Then convert back to the current dblock size.
2893         */
2894        b = dm_sector_div_up(b, li->cache->discard_block_size);
2895        sector_div(e, li->cache->discard_block_size);
2896
2897        /*
2898         * The origin may have shrunk, so we need to check we're still in
2899         * bounds.
2900         */
2901        if (e > from_dblock(li->cache->discard_nr_blocks))
2902                e = from_dblock(li->cache->discard_nr_blocks);
2903
2904        for (; b < e; b++)
2905                set_discard(li->cache, to_dblock(b));
2906}
2907
2908static int load_discard(void *context, sector_t discard_block_size,
2909                        dm_dblock_t dblock, bool discard)
2910{
2911        struct discard_load_info *li = context;
2912
2913        li->block_size = discard_block_size;
2914
2915        if (discard) {
2916                if (from_dblock(dblock) == li->discard_end)
2917                        /*
2918                         * We're already in a discard range, just extend it.
2919                         */
2920                        li->discard_end = li->discard_end + 1ULL;
2921
2922                else {
2923                        /*
2924                         * Emit the old range and start a new one.
2925                         */
2926                        set_discard_range(li);
2927                        li->discard_begin = from_dblock(dblock);
2928                        li->discard_end = li->discard_begin + 1ULL;
2929                }
2930        } else {
2931                set_discard_range(li);
2932                li->discard_begin = li->discard_end = 0;
2933        }
2934
2935        return 0;
2936}
2937
2938static dm_cblock_t get_cache_dev_size(struct cache *cache)
2939{
2940        sector_t size = get_dev_size(cache->cache_dev);
2941        (void) sector_div(size, cache->sectors_per_block);
2942        return to_cblock(size);
2943}
2944
2945static bool can_resize(struct cache *cache, dm_cblock_t new_size)
2946{
2947        if (from_cblock(new_size) > from_cblock(cache->cache_size)) {
2948                if (cache->sized) {
2949                        DMERR("%s: unable to extend cache due to missing cache table reload",
2950                              cache_device_name(cache));
2951                        return false;
2952                }
2953        }
2954
2955        /*
2956         * We can't drop a dirty block when shrinking the cache.
2957         */
2958        while (from_cblock(new_size) < from_cblock(cache->cache_size)) {
2959                new_size = to_cblock(from_cblock(new_size) + 1);
2960                if (is_dirty(cache, new_size)) {
2961                        DMERR("%s: unable to shrink cache; cache block %llu is dirty",
2962                              cache_device_name(cache),
2963                              (unsigned long long) from_cblock(new_size));
2964                        return false;
2965                }
2966        }
2967
2968        return true;
2969}
2970
2971static int resize_cache_dev(struct cache *cache, dm_cblock_t new_size)
2972{
2973        int r;
2974
2975        r = dm_cache_resize(cache->cmd, new_size);
2976        if (r) {
2977                DMERR("%s: could not resize cache metadata", cache_device_name(cache));
2978                metadata_operation_failed(cache, "dm_cache_resize", r);
2979                return r;
2980        }
2981
2982        set_cache_size(cache, new_size);
2983
2984        return 0;
2985}
2986
2987static int cache_preresume(struct dm_target *ti)
2988{
2989        int r = 0;
2990        struct cache *cache = ti->private;
2991        dm_cblock_t csize = get_cache_dev_size(cache);
2992
2993        /*
2994         * Check to see if the cache has resized.
2995         */
2996        if (!cache->sized) {
2997                r = resize_cache_dev(cache, csize);
2998                if (r)
2999                        return r;
3000
3001                cache->sized = true;
3002
3003        } else if (csize != cache->cache_size) {
3004                if (!can_resize(cache, csize))
3005                        return -EINVAL;
3006
3007                r = resize_cache_dev(cache, csize);
3008                if (r)
3009                        return r;
3010        }
3011
3012        if (!cache->loaded_mappings) {
3013                r = dm_cache_load_mappings(cache->cmd, cache->policy,
3014                                           load_mapping, cache);
3015                if (r) {
3016                        DMERR("%s: could not load cache mappings", cache_device_name(cache));
3017                        metadata_operation_failed(cache, "dm_cache_load_mappings", r);
3018                        return r;
3019                }
3020
3021                cache->loaded_mappings = true;
3022        }
3023
3024        if (!cache->loaded_discards) {
3025                struct discard_load_info li;
3026
3027                /*
3028                 * The discard bitset could have been resized, or the
3029                 * discard block size changed.  To be safe we start by
3030                 * setting every dblock to not discarded.
3031                 */
3032                clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks));
3033
3034                discard_load_info_init(cache, &li);
3035                r = dm_cache_load_discards(cache->cmd, load_discard, &li);
3036                if (r) {
3037                        DMERR("%s: could not load origin discards", cache_device_name(cache));
3038                        metadata_operation_failed(cache, "dm_cache_load_discards", r);
3039                        return r;
3040                }
3041                set_discard_range(&li);
3042
3043                cache->loaded_discards = true;
3044        }
3045
3046        return r;
3047}
3048
3049static void cache_resume(struct dm_target *ti)
3050{
3051        struct cache *cache = ti->private;
3052
3053        cache->need_tick_bio = true;
3054        allow_background_work(cache);
3055        do_waker(&cache->waker.work);
3056}
3057
3058static void emit_flags(struct cache *cache, char *result,
3059                       unsigned maxlen, ssize_t *sz_ptr)
3060{
3061        ssize_t sz = *sz_ptr;
3062        struct cache_features *cf = &cache->features;
3063        unsigned count = (cf->metadata_version == 2) + !cf->discard_passdown + 1;
3064
3065        DMEMIT("%u ", count);
3066
3067        if (cf->metadata_version == 2)
3068                DMEMIT("metadata2 ");
3069
3070        if (writethrough_mode(cache))
3071                DMEMIT("writethrough ");
3072
3073        else if (passthrough_mode(cache))
3074                DMEMIT("passthrough ");
3075
3076        else if (writeback_mode(cache))
3077                DMEMIT("writeback ");
3078
3079        else {
3080                DMEMIT("unknown ");
3081                DMERR("%s: internal error: unknown io mode: %d",
3082                      cache_device_name(cache), (int) cf->io_mode);
3083        }
3084
3085        if (!cf->discard_passdown)
3086                DMEMIT("no_discard_passdown ");
3087
3088        *sz_ptr = sz;
3089}
3090
3091/*
3092 * Status format:
3093 *
3094 * <metadata block size> <#used metadata blocks>/<#total metadata blocks>
3095 * <cache block size> <#used cache blocks>/<#total cache blocks>
3096 * <#read hits> <#read misses> <#write hits> <#write misses>
3097 * <#demotions> <#promotions> <#dirty>
3098 * <#features> <features>*
3099 * <#core args> <core args>
3100 * <policy name> <#policy args> <policy args>* <cache metadata mode> <needs_check>
3101 */
3102static void cache_status(struct dm_target *ti, status_type_t type,
3103                         unsigned status_flags, char *result, unsigned maxlen)
3104{
3105        int r = 0;
3106        unsigned i;
3107        ssize_t sz = 0;
3108        dm_block_t nr_free_blocks_metadata = 0;
3109        dm_block_t nr_blocks_metadata = 0;
3110        char buf[BDEVNAME_SIZE];
3111        struct cache *cache = ti->private;
3112        dm_cblock_t residency;
3113        bool needs_check;
3114
3115        switch (type) {
3116        case STATUSTYPE_INFO:
3117                if (get_cache_mode(cache) == CM_FAIL) {
3118                        DMEMIT("Fail");
3119                        break;
3120                }
3121
3122                /* Commit to ensure statistics aren't out-of-date */
3123                if (!(status_flags & DM_STATUS_NOFLUSH_FLAG) && !dm_suspended(ti))
3124                        (void) commit(cache, false);
3125
3126                r = dm_cache_get_free_metadata_block_count(cache->cmd, &nr_free_blocks_metadata);
3127                if (r) {
3128                        DMERR("%s: dm_cache_get_free_metadata_block_count returned %d",
3129                              cache_device_name(cache), r);
3130                        goto err;
3131                }
3132
3133                r = dm_cache_get_metadata_dev_size(cache->cmd, &nr_blocks_metadata);
3134                if (r) {
3135                        DMERR("%s: dm_cache_get_metadata_dev_size returned %d",
3136                              cache_device_name(cache), r);
3137                        goto err;
3138                }
3139
3140                residency = policy_residency(cache->policy);
3141
3142                DMEMIT("%u %llu/%llu %llu %llu/%llu %u %u %u %u %u %u %lu ",
3143                       (unsigned)DM_CACHE_METADATA_BLOCK_SIZE,
3144                       (unsigned long long)(nr_blocks_metadata - nr_free_blocks_metadata),
3145                       (unsigned long long)nr_blocks_metadata,
3146                       (unsigned long long)cache->sectors_per_block,
3147                       (unsigned long long) from_cblock(residency),
3148                       (unsigned long long) from_cblock(cache->cache_size),
3149                       (unsigned) atomic_read(&cache->stats.read_hit),
3150                       (unsigned) atomic_read(&cache->stats.read_miss),
3151                       (unsigned) atomic_read(&cache->stats.write_hit),
3152                       (unsigned) atomic_read(&cache->stats.write_miss),
3153                       (unsigned) atomic_read(&cache->stats.demotion),
3154                       (unsigned) atomic_read(&cache->stats.promotion),
3155                       (unsigned long) atomic_read(&cache->nr_dirty));
3156
3157                emit_flags(cache, result, maxlen, &sz);
3158
3159                DMEMIT("2 migration_threshold %llu ", (unsigned long long) cache->migration_threshold);
3160
3161                DMEMIT("%s ", dm_cache_policy_get_name(cache->policy));
3162                if (sz < maxlen) {
3163                        r = policy_emit_config_values(cache->policy, result, maxlen, &sz);
3164                        if (r)
3165                                DMERR("%s: policy_emit_config_values returned %d",
3166                                      cache_device_name(cache), r);
3167                }
3168
3169                if (get_cache_mode(cache) == CM_READ_ONLY)
3170                        DMEMIT("ro ");
3171                else
3172                        DMEMIT("rw ");
3173
3174                r = dm_cache_metadata_needs_check(cache->cmd, &needs_check);
3175
3176                if (r || needs_check)
3177                        DMEMIT("needs_check ");
3178                else
3179                        DMEMIT("- ");
3180
3181                break;
3182
3183        case STATUSTYPE_TABLE:
3184                format_dev_t(buf, cache->metadata_dev->bdev->bd_dev);
3185                DMEMIT("%s ", buf);
3186                format_dev_t(buf, cache->cache_dev->bdev->bd_dev);
3187                DMEMIT("%s ", buf);
3188                format_dev_t(buf, cache->origin_dev->bdev->bd_dev);
3189                DMEMIT("%s", buf);
3190
3191                for (i = 0; i < cache->nr_ctr_args - 1; i++)
3192                        DMEMIT(" %s", cache->ctr_args[i]);
3193                if (cache->nr_ctr_args)
3194                        DMEMIT(" %s", cache->ctr_args[cache->nr_ctr_args - 1]);
3195        }
3196
3197        return;
3198
3199err:
3200        DMEMIT("Error");
3201}
3202
3203/*
3204 * Defines a range of cblocks, begin to (end - 1) are in the range.  end is
3205 * the one-past-the-end value.
3206 */
3207struct cblock_range {
3208        dm_cblock_t begin;
3209        dm_cblock_t end;
3210};
3211
3212/*
3213 * A cache block range can take two forms:
3214 *
3215 * i) A single cblock, eg. '3456'
3216 * ii) A begin and end cblock with a dash between, eg. 123-234
3217 */
3218static int parse_cblock_range(struct cache *cache, const char *str,
3219                              struct cblock_range *result)
3220{
3221        char dummy;
3222        uint64_t b, e;
3223        int r;
3224
3225        /*
3226         * Try and parse form (ii) first.
3227         */
3228        r = sscanf(str, "%llu-%llu%c", &b, &e, &dummy);
3229        if (r < 0)
3230                return r;
3231
3232        if (r == 2) {
3233                result->begin = to_cblock(b);
3234                result->end = to_cblock(e);
3235                return 0;
3236        }
3237
3238        /*
3239         * That didn't work, try form (i).
3240         */
3241        r = sscanf(str, "%llu%c", &b, &dummy);
3242        if (r < 0)
3243                return r;
3244
3245        if (r == 1) {
3246                result->begin = to_cblock(b);
3247                result->end = to_cblock(from_cblock(result->begin) + 1u);
3248                return 0;
3249        }
3250
3251        DMERR("%s: invalid cblock range '%s'", cache_device_name(cache), str);
3252        return -EINVAL;
3253}
3254
3255static int validate_cblock_range(struct cache *cache, struct cblock_range *range)
3256{
3257        uint64_t b = from_cblock(range->begin);
3258        uint64_t e = from_cblock(range->end);
3259        uint64_t n = from_cblock(cache->cache_size);
3260
3261        if (b >= n) {
3262                DMERR("%s: begin cblock out of range: %llu >= %llu",
3263                      cache_device_name(cache), b, n);
3264                return -EINVAL;
3265        }
3266
3267        if (e > n) {
3268                DMERR("%s: end cblock out of range: %llu > %llu",
3269                      cache_device_name(cache), e, n);
3270                return -EINVAL;
3271        }
3272
3273        if (b >= e) {
3274                DMERR("%s: invalid cblock range: %llu >= %llu",
3275                      cache_device_name(cache), b, e);
3276                return -EINVAL;
3277        }
3278
3279        return 0;
3280}
3281
3282static inline dm_cblock_t cblock_succ(dm_cblock_t b)
3283{
3284        return to_cblock(from_cblock(b) + 1);
3285}
3286
3287static int request_invalidation(struct cache *cache, struct cblock_range *range)
3288{
3289        int r = 0;
3290
3291        /*
3292         * We don't need to do any locking here because we know we're in
3293         * passthrough mode.  There's is potential for a race between an
3294         * invalidation triggered by an io and an invalidation message.  This
3295         * is harmless, we must not worry if the policy call fails.
3296         */
3297        while (range->begin != range->end) {
3298                r = invalidate_cblock(cache, range->begin);
3299                if (r)
3300                        return r;
3301
3302                range->begin = cblock_succ(range->begin);
3303        }
3304
3305        cache->commit_requested = true;
3306        return r;
3307}
3308
3309static int process_invalidate_cblocks_message(struct cache *cache, unsigned count,
3310                                              const char **cblock_ranges)
3311{
3312        int r = 0;
3313        unsigned i;
3314        struct cblock_range range;
3315
3316        if (!passthrough_mode(cache)) {
3317                DMERR("%s: cache has to be in passthrough mode for invalidation",
3318                      cache_device_name(cache));
3319                return -EPERM;
3320        }
3321
3322        for (i = 0; i < count; i++) {
3323                r = parse_cblock_range(cache, cblock_ranges[i], &range);
3324                if (r)
3325                        break;
3326
3327                r = validate_cblock_range(cache, &range);
3328                if (r)
3329                        break;
3330
3331                /*
3332                 * Pass begin and end origin blocks to the worker and wake it.
3333                 */
3334                r = request_invalidation(cache, &range);
3335                if (r)
3336                        break;
3337        }
3338
3339        return r;
3340}
3341
3342/*
3343 * Supports
3344 *      "<key> <value>"
3345 * and
3346 *     "invalidate_cblocks [(<begin>)|(<begin>-<end>)]*
3347 *
3348 * The key migration_threshold is supported by the cache target core.
3349 */
3350static int cache_message(struct dm_target *ti, unsigned argc, char **argv,
3351                         char *result, unsigned maxlen)
3352{
3353        struct cache *cache = ti->private;
3354
3355        if (!argc)
3356                return -EINVAL;
3357
3358        if (get_cache_mode(cache) >= CM_READ_ONLY) {
3359                DMERR("%s: unable to service cache target messages in READ_ONLY or FAIL mode",
3360                      cache_device_name(cache));
3361                return -EOPNOTSUPP;
3362        }
3363
3364        if (!strcasecmp(argv[0], "invalidate_cblocks"))
3365                return process_invalidate_cblocks_message(cache, argc - 1, (const char **) argv + 1);
3366
3367        if (argc != 2)
3368                return -EINVAL;
3369
3370        return set_config_value(cache, argv[0], argv[1]);
3371}
3372
3373static int cache_iterate_devices(struct dm_target *ti,
3374                                 iterate_devices_callout_fn fn, void *data)
3375{
3376        int r = 0;
3377        struct cache *cache = ti->private;
3378
3379        r = fn(ti, cache->cache_dev, 0, get_dev_size(cache->cache_dev), data);
3380        if (!r)
3381                r = fn(ti, cache->origin_dev, 0, ti->len, data);
3382
3383        return r;
3384}
3385
3386static bool origin_dev_supports_discard(struct block_device *origin_bdev)
3387{
3388        struct request_queue *q = bdev_get_queue(origin_bdev);
3389
3390        return blk_queue_discard(q);
3391}
3392
3393/*
3394 * If discard_passdown was enabled verify that the origin device
3395 * supports discards.  Disable discard_passdown if not.
3396 */
3397static void disable_passdown_if_not_supported(struct cache *cache)
3398{
3399        struct block_device *origin_bdev = cache->origin_dev->bdev;
3400        struct queue_limits *origin_limits = &bdev_get_queue(origin_bdev)->limits;
3401        const char *reason = NULL;
3402        char buf[BDEVNAME_SIZE];
3403
3404        if (!cache->features.discard_passdown)
3405                return;
3406
3407        if (!origin_dev_supports_discard(origin_bdev))
3408                reason = "discard unsupported";
3409
3410        else if (origin_limits->max_discard_sectors < cache->sectors_per_block)
3411                reason = "max discard sectors smaller than a block";
3412
3413        if (reason) {
3414                DMWARN("Origin device (%s) %s: Disabling discard passdown.",
3415                       bdevname(origin_bdev, buf), reason);
3416                cache->features.discard_passdown = false;
3417        }
3418}
3419
3420static void set_discard_limits(struct cache *cache, struct queue_limits *limits)
3421{
3422        struct block_device *origin_bdev = cache->origin_dev->bdev;
3423        struct queue_limits *origin_limits = &bdev_get_queue(origin_bdev)->limits;
3424
3425        if (!cache->features.discard_passdown) {
3426                /* No passdown is done so setting own virtual limits */
3427                limits->max_discard_sectors = min_t(sector_t, cache->discard_block_size * 1024,
3428                                                    cache->origin_sectors);
3429                limits->discard_granularity = cache->discard_block_size << SECTOR_SHIFT;
3430                return;
3431        }
3432
3433        /*
3434         * cache_iterate_devices() is stacking both origin and fast device limits
3435         * but discards aren't passed to fast device, so inherit origin's limits.
3436         */
3437        limits->max_discard_sectors = origin_limits->max_discard_sectors;
3438        limits->max_hw_discard_sectors = origin_limits->max_hw_discard_sectors;
3439        limits->discard_granularity = origin_limits->discard_granularity;
3440        limits->discard_alignment = origin_limits->discard_alignment;
3441        limits->discard_misaligned = origin_limits->discard_misaligned;
3442}
3443
3444static void cache_io_hints(struct dm_target *ti, struct queue_limits *limits)
3445{
3446        struct cache *cache = ti->private;
3447        uint64_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;
3448
3449        /*
3450         * If the system-determined stacked limits are compatible with the
3451         * cache's blocksize (io_opt is a factor) do not override them.
3452         */
3453        if (io_opt_sectors < cache->sectors_per_block ||
3454            do_div(io_opt_sectors, cache->sectors_per_block)) {
3455                blk_limits_io_min(limits, cache->sectors_per_block << SECTOR_SHIFT);
3456                blk_limits_io_opt(limits, cache->sectors_per_block << SECTOR_SHIFT);
3457        }
3458
3459        disable_passdown_if_not_supported(cache);
3460        set_discard_limits(cache, limits);
3461}
3462
3463/*----------------------------------------------------------------*/
3464
3465static struct target_type cache_target = {
3466        .name = "cache",
3467        .version = {2, 2, 0},
3468        .module = THIS_MODULE,
3469        .ctr = cache_ctr,
3470        .dtr = cache_dtr,
3471        .map = cache_map,
3472        .end_io = cache_end_io,
3473        .postsuspend = cache_postsuspend,
3474        .preresume = cache_preresume,
3475        .resume = cache_resume,
3476        .status = cache_status,
3477        .message = cache_message,
3478        .iterate_devices = cache_iterate_devices,
3479        .io_hints = cache_io_hints,
3480};
3481
3482static int __init dm_cache_init(void)
3483{
3484        int r;
3485
3486        migration_cache = KMEM_CACHE(dm_cache_migration, 0);
3487        if (!migration_cache)
3488                return -ENOMEM;
3489
3490        r = dm_register_target(&cache_target);
3491        if (r) {
3492                DMERR("cache target registration failed: %d", r);
3493                kmem_cache_destroy(migration_cache);
3494                return r;
3495        }
3496
3497        return 0;
3498}
3499
3500static void __exit dm_cache_exit(void)
3501{
3502        dm_unregister_target(&cache_target);
3503        kmem_cache_destroy(migration_cache);
3504}
3505
3506module_init(dm_cache_init);
3507module_exit(dm_cache_exit);
3508
3509MODULE_DESCRIPTION(DM_NAME " cache target");
3510MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
3511MODULE_LICENSE("GPL");
3512