drivers/md/dm-cache-target.c

   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.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/slab.h>
  19 #include <linux/vmalloc.h>
  20
  21 #define DM_MSG_PREFIX "cache"
  22
  23 DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(cache_copy_throttle,
  24         "A percentage of time allocated for copying to and/or from cache");
  25
  26 /*----------------------------------------------------------------*/
  27
  28 #define IOT_RESOLUTION 4
  29
  30 struct io_tracker {
  31         spinlock_t lock;
  32
  33         /*
  34          * Sectors of in-flight IO.
  35          */
  36         sector_t in_flight;
  37
  38         /*
  39          * The time, in jiffies, when this device became idle (if it is
  40          * indeed idle).
  41          */
  42         unsigned long idle_time;
  43         unsigned long last_update_time;
  44 };
  45
  46 static void iot_init(struct io_tracker *iot)
  47 {
  48         spin_lock_init(&iot->lock);
  49         iot->in_flight = 0ul;
  50         iot->idle_time = 0ul;
  51         iot->last_update_time = jiffies;
  52 }
  53
  54 static bool __iot_idle_for(struct io_tracker *iot, unsigned long jifs)
  55 {
  56         if (iot->in_flight)
  57                 return false;
  58
  59         return time_after(jiffies, iot->idle_time + jifs);
  60 }
  61
  62 static bool iot_idle_for(struct io_tracker *iot, unsigned long jifs)
  63 {
  64         bool r;
  65         unsigned long flags;
  66
  67         spin_lock_irqsave(&iot->lock, flags);
  68         r = __iot_idle_for(iot, jifs);
  69         spin_unlock_irqrestore(&iot->lock, flags);
  70
  71         return r;
  72 }
  73
  74 static void iot_io_begin(struct io_tracker *iot, sector_t len)
  75 {
  76         unsigned long flags;
  77
  78         spin_lock_irqsave(&iot->lock, flags);
  79         iot->in_flight += len;
  80         spin_unlock_irqrestore(&iot->lock, flags);
  81 }
  82
  83 static void __iot_io_end(struct io_tracker *iot, sector_t len)
  84 {
  85         iot->in_flight -= len;
  86         if (!iot->in_flight)
  87                 iot->idle_time = jiffies;
  88 }
  89
  90 static void iot_io_end(struct io_tracker *iot, sector_t len)
  91 {
  92         unsigned long flags;
  93
  94         spin_lock_irqsave(&iot->lock, flags);
  95         __iot_io_end(iot, len);
  96         spin_unlock_irqrestore(&iot->lock, flags);
  97 }
  98
  99 /*----------------------------------------------------------------*/
 100
 101 /*
 102  * Glossary:
 103  *
 104  * oblock: index of an origin block
 105  * cblock: index of a cache block
 106  * promotion: movement of a block from origin to cache
 107  * demotion: movement of a block from cache to origin
 108  * migration: movement of a block between the origin and cache device,
 109  *            either direction
 110  */
 111
 112 /*----------------------------------------------------------------*/
 113
 114 /*
 115  * There are a couple of places where we let a bio run, but want to do some
 116  * work before calling its endio function.  We do this by temporarily
 117  * changing the endio fn.
 118  */
 119 struct dm_hook_info {
 120         bio_end_io_t *bi_end_io;
 121         void *bi_private;
 122 };
 123
 124 static void dm_hook_bio(struct dm_hook_info *h, struct bio *bio,
 125                         bio_end_io_t *bi_end_io, void *bi_private)
 126 {
 127         h->bi_end_io = bio->bi_end_io;
 128         h->bi_private = bio->bi_private;
 129
 130         bio->bi_end_io = bi_end_io;
 131         bio->bi_private = bi_private;
 132 }
 133
 134 static void dm_unhook_bio(struct dm_hook_info *h, struct bio *bio)
 135 {
 136         bio->bi_end_io = h->bi_end_io;
 137         bio->bi_private = h->bi_private;
 138 }
 139
 140 /*----------------------------------------------------------------*/
 141
 142 #define MIGRATION_POOL_SIZE 128
 143 #define COMMIT_PERIOD HZ
 144 #define MIGRATION_COUNT_WINDOW 10
 145
 146 /*
 147  * The block size of the device holding cache data must be
 148  * between 32KB and 1GB.
 149  */
 150 #define DATA_DEV_BLOCK_SIZE_MIN_SECTORS (32 * 1024 >> SECTOR_SHIFT)
 151 #define DATA_DEV_BLOCK_SIZE_MAX_SECTORS (1024 * 1024 * 1024 >> SECTOR_SHIFT)
 152
 153 enum cache_metadata_mode {
 154         CM_WRITE,               /* metadata may be changed */
 155         CM_READ_ONLY,           /* metadata may not be changed */
 156         CM_FAIL
 157 };
 158
 159 enum cache_io_mode {
 160         /*
 161          * Data is written to cached blocks only.  These blocks are marked
 162          * dirty.  If you lose the cache device you will lose data.
 163          * Potential performance increase for both reads and writes.
 164          */
 165         CM_IO_WRITEBACK,
 166
 167         /*
 168          * Data is written to both cache and origin.  Blocks are never
 169          * dirty.  Potential performance benfit for reads only.
 170          */
 171         CM_IO_WRITETHROUGH,
 172
 173         /*
 174          * A degraded mode useful for various cache coherency situations
 175          * (eg, rolling back snapshots).  Reads and writes always go to the
 176          * origin.  If a write goes to a cached oblock, then the cache
 177          * block is invalidated.
 178          */
 179         CM_IO_PASSTHROUGH
 180 };
 181
 182 struct cache_features {
 183         enum cache_metadata_mode mode;
 184         enum cache_io_mode io_mode;
 185 };
 186
 187 struct cache_stats {
 188         atomic_t read_hit;
 189         atomic_t read_miss;
 190         atomic_t write_hit;
 191         atomic_t write_miss;
 192         atomic_t demotion;
 193         atomic_t promotion;
 194         atomic_t copies_avoided;
 195         atomic_t cache_cell_clash;
 196         atomic_t commit_count;
 197         atomic_t discard_count;
 198 };
 199
 200 /*
 201  * Defines a range of cblocks, begin to (end - 1) are in the range.  end is
 202  * the one-past-the-end value.
 203  */
 204 struct cblock_range {
 205         dm_cblock_t begin;
 206         dm_cblock_t end;
 207 };
 208
 209 struct invalidation_request {
 210         struct list_head list;
 211         struct cblock_range *cblocks;
 212
 213         atomic_t complete;
 214         int err;
 215
 216         wait_queue_head_t result_wait;
 217 };
 218
 219 struct cache {
 220         struct dm_target *ti;
 221         struct dm_target_callbacks callbacks;
 222
 223         struct dm_cache_metadata *cmd;
 224
 225         /*
 226          * Metadata is written to this device.
 227          */
 228         struct dm_dev *metadata_dev;
 229
 230         /*
 231          * The slower of the two data devices.  Typically a spindle.
 232          */
 233         struct dm_dev *origin_dev;
 234
 235         /*
 236          * The faster of the two data devices.  Typically an SSD.
 237          */
 238         struct dm_dev *cache_dev;
 239
 240         /*
 241          * Size of the origin device in _complete_ blocks and native sectors.
 242          */
 243         dm_oblock_t origin_blocks;
 244         sector_t origin_sectors;
 245
 246         /*
 247          * Size of the cache device in blocks.
 248          */
 249         dm_cblock_t cache_size;
 250
 251         /*
 252          * Fields for converting from sectors to blocks.
 253          */
 254         uint32_t sectors_per_block;
 255         int sectors_per_block_shift;
 256
 257         spinlock_t lock;
 258         struct list_head deferred_cells;
 259         struct bio_list deferred_bios;
 260         struct bio_list deferred_flush_bios;
 261         struct bio_list deferred_writethrough_bios;
 262         struct list_head quiesced_migrations;
 263         struct list_head completed_migrations;
 264         struct list_head need_commit_migrations;
 265         sector_t migration_threshold;
 266         wait_queue_head_t migration_wait;
 267         atomic_t nr_allocated_migrations;
 268
 269         /*
 270          * The number of in flight migrations that are performing
 271          * background io. eg, promotion, writeback.
 272          */
 273         atomic_t nr_io_migrations;
 274
 275         wait_queue_head_t quiescing_wait;
 276         atomic_t quiescing;
 277         atomic_t quiescing_ack;
 278
 279         /*
 280          * cache_size entries, dirty if set
 281          */
 282         atomic_t nr_dirty;
 283         unsigned long *dirty_bitset;
 284
 285         /*
 286          * origin_blocks entries, discarded if set.
 287          */
 288         dm_dblock_t discard_nr_blocks;
 289         unsigned long *discard_bitset;
 290         uint32_t discard_block_size; /* a power of 2 times sectors per block */
 291
 292         /*
 293          * Rather than reconstructing the table line for the status we just
 294          * save it and regurgitate.
 295          */
 296         unsigned nr_ctr_args;
 297         const char **ctr_args;
 298
 299         struct dm_kcopyd_client *copier;
 300         struct workqueue_struct *wq;
 301         struct work_struct worker;
 302
 303         struct delayed_work waker;
 304         unsigned long last_commit_jiffies;
 305
 306         struct dm_bio_prison *prison;
 307         struct dm_deferred_set *all_io_ds;
 308
 309         mempool_t *migration_pool;
 310
 311         struct dm_cache_policy *policy;
 312         unsigned policy_nr_args;
 313
 314         bool need_tick_bio:1;
 315         bool sized:1;
 316         bool invalidate:1;
 317         bool commit_requested:1;
 318         bool loaded_mappings:1;
 319         bool loaded_discards:1;
 320
 321         /*
 322          * Cache features such as write-through.
 323          */
 324         struct cache_features features;
 325
 326         struct cache_stats stats;
 327
 328         /*
 329          * Invalidation fields.
 330          */
 331         spinlock_t invalidation_lock;
 332         struct list_head invalidation_requests;
 333
 334         struct io_tracker origin_tracker;
 335 };
 336
 337 struct per_bio_data {
 338         bool tick:1;
 339         unsigned req_nr:2;
 340         struct dm_deferred_entry *all_io_entry;
 341         struct dm_hook_info hook_info;
 342         sector_t len;
 343
 344         /*
 345          * writethrough fields.  These MUST remain at the end of this
 346          * structure and the 'cache' member must be the first as it
 347          * is used to determine the offset of the writethrough fields.
 348          */
 349         struct cache *cache;
 350         dm_cblock_t cblock;
 351         struct dm_bio_details bio_details;
 352 };
 353
 354 struct dm_cache_migration {
 355         struct list_head list;
 356         struct cache *cache;
 357
 358         unsigned long start_jiffies;
 359         dm_oblock_t old_oblock;
 360         dm_oblock_t new_oblock;
 361         dm_cblock_t cblock;
 362
 363         bool err:1;
 364         bool discard:1;
 365         bool writeback:1;
 366         bool demote:1;
 367         bool promote:1;
 368         bool requeue_holder:1;
 369         bool invalidate:1;
 370
 371         struct dm_bio_prison_cell *old_ocell;
 372         struct dm_bio_prison_cell *new_ocell;
 373 };
 374
 375 /*
 376  * Processing a bio in the worker thread may require these memory
 377  * allocations.  We prealloc to avoid deadlocks (the same worker thread
 378  * frees them back to the mempool).
 379  */
 380 struct prealloc {
 381         struct dm_cache_migration *mg;
 382         struct dm_bio_prison_cell *cell1;
 383         struct dm_bio_prison_cell *cell2;
 384 };
 385
 386 static enum cache_metadata_mode get_cache_mode(struct cache *cache);
 387
 388 static void wake_worker(struct cache *cache)
 389 {
 390         queue_work(cache->wq, &cache->worker);
 391 }
 392
 393 /*----------------------------------------------------------------*/
 394
 395 static struct dm_bio_prison_cell *alloc_prison_cell(struct cache *cache)
 396 {
 397         /* FIXME: change to use a local slab. */
 398         return dm_bio_prison_alloc_cell(cache->prison, GFP_NOWAIT);
 399 }
 400
 401 static void free_prison_cell(struct cache *cache, struct dm_bio_prison_cell *cell)
 402 {
 403         dm_bio_prison_free_cell(cache->prison, cell);
 404 }
 405
 406 static struct dm_cache_migration *alloc_migration(struct cache *cache)
 407 {
 408         struct dm_cache_migration *mg;
 409
 410         mg = mempool_alloc(cache->migration_pool, GFP_NOWAIT);
 411         if (mg) {
 412                 mg->cache = cache;
 413                 atomic_inc(&mg->cache->nr_allocated_migrations);
 414         }
 415
 416         return mg;
 417 }
 418
 419 static void free_migration(struct dm_cache_migration *mg)
 420 {
 421         struct cache *cache = mg->cache;
 422
 423         if (atomic_dec_and_test(&cache->nr_allocated_migrations))
 424                 wake_up(&cache->migration_wait);
 425
 426         mempool_free(mg, cache->migration_pool);
 427         wake_worker(cache);
 428 }
 429
 430 static int prealloc_data_structs(struct cache *cache, struct prealloc *p)
 431 {
 432         if (!p->mg) {
 433                 p->mg = alloc_migration(cache);
 434                 if (!p->mg)
 435                         return -ENOMEM;
 436         }
 437
 438         if (!p->cell1) {
 439                 p->cell1 = alloc_prison_cell(cache);
 440                 if (!p->cell1)
 441                         return -ENOMEM;
 442         }
 443
 444         if (!p->cell2) {
 445                 p->cell2 = alloc_prison_cell(cache);
 446                 if (!p->cell2)
 447                         return -ENOMEM;
 448         }
 449
 450         return 0;
 451 }
 452
 453 static void prealloc_free_structs(struct cache *cache, struct prealloc *p)
 454 {
 455         if (p->cell2)
 456                 free_prison_cell(cache, p->cell2);
 457
 458         if (p->cell1)
 459                 free_prison_cell(cache, p->cell1);
 460
 461         if (p->mg)
 462                 free_migration(p->mg);
 463 }
 464
 465 static struct dm_cache_migration *prealloc_get_migration(struct prealloc *p)
 466 {
 467         struct dm_cache_migration *mg = p->mg;
 468
 469         BUG_ON(!mg);
 470         p->mg = NULL;
 471
 472         return mg;
 473 }
 474
 475 /*
 476  * You must have a cell within the prealloc struct to return.  If not this
 477  * function will BUG() rather than returning NULL.
 478  */
 479 static struct dm_bio_prison_cell *prealloc_get_cell(struct prealloc *p)
 480 {
 481         struct dm_bio_prison_cell *r = NULL;
 482
 483         if (p->cell1) {
 484                 r = p->cell1;
 485                 p->cell1 = NULL;
 486
 487         } else if (p->cell2) {
 488                 r = p->cell2;
 489                 p->cell2 = NULL;
 490         } else
 491                 BUG();
 492
 493         return r;
 494 }
 495
 496 /*
 497  * You can't have more than two cells in a prealloc struct.  BUG() will be
 498  * called if you try and overfill.
 499  */
 500 static void prealloc_put_cell(struct prealloc *p, struct dm_bio_prison_cell *cell)
 501 {
 502         if (!p->cell2)
 503                 p->cell2 = cell;
 504
 505         else if (!p->cell1)
 506                 p->cell1 = cell;
 507
 508         else
 509                 BUG();
 510 }
 511
 512 /*----------------------------------------------------------------*/
 513
 514 static void build_key(dm_oblock_t begin, dm_oblock_t end, struct dm_cell_key *key)
 515 {
 516         key->virtual = 0;
 517         key->dev = 0;
 518         key->block_begin = from_oblock(begin);
 519         key->block_end = from_oblock(end);
 520 }
 521
 522 /*
 523  * The caller hands in a preallocated cell, and a free function for it.
 524  * The cell will be freed if there's an error, or if it wasn't used because
 525  * a cell with that key already exists.
 526  */
 527 typedef void (*cell_free_fn)(void *context, struct dm_bio_prison_cell *cell);
 528
 529 static int bio_detain_range(struct cache *cache, dm_oblock_t oblock_begin, dm_oblock_t oblock_end,
 530                             struct bio *bio, struct dm_bio_prison_cell *cell_prealloc,
 531                             cell_free_fn free_fn, void *free_context,
 532                             struct dm_bio_prison_cell **cell_result)
 533 {
 534         int r;
 535         struct dm_cell_key key;
 536
 537         build_key(oblock_begin, oblock_end, &key);
 538         r = dm_bio_detain(cache->prison, &key, bio, cell_prealloc, cell_result);
 539         if (r)
 540                 free_fn(free_context, cell_prealloc);
 541
 542         return r;
 543 }
 544
 545 static int bio_detain(struct cache *cache, dm_oblock_t oblock,
 546                       struct bio *bio, struct dm_bio_prison_cell *cell_prealloc,
 547                       cell_free_fn free_fn, void *free_context,
 548                       struct dm_bio_prison_cell **cell_result)
 549 {
 550         dm_oblock_t end = to_oblock(from_oblock(oblock) + 1ULL);
 551         return bio_detain_range(cache, oblock, end, bio,
 552                                 cell_prealloc, free_fn, free_context, cell_result);
 553 }
 554
 555 static int get_cell(struct cache *cache,
 556                     dm_oblock_t oblock,
 557                     struct prealloc *structs,
 558                     struct dm_bio_prison_cell **cell_result)
 559 {
 560         int r;
 561         struct dm_cell_key key;
 562         struct dm_bio_prison_cell *cell_prealloc;
 563
 564         cell_prealloc = prealloc_get_cell(structs);
 565
 566         build_key(oblock, to_oblock(from_oblock(oblock) + 1ULL), &key);
 567         r = dm_get_cell(cache->prison, &key, cell_prealloc, cell_result);
 568         if (r)
 569                 prealloc_put_cell(structs, cell_prealloc);
 570
 571         return r;
 572 }
 573
 574 /*----------------------------------------------------------------*/
 575
 576 static bool is_dirty(struct cache *cache, dm_cblock_t b)
 577 {
 578         return test_bit(from_cblock(b), cache->dirty_bitset);
 579 }
 580
 581 static void set_dirty(struct cache *cache, dm_oblock_t oblock, dm_cblock_t cblock)
 582 {
 583         if (!test_and_set_bit(from_cblock(cblock), cache->dirty_bitset)) {
 584                 atomic_inc(&cache->nr_dirty);
 585                 policy_set_dirty(cache->policy, oblock);
 586         }
 587 }
 588
 589 static void clear_dirty(struct cache *cache, dm_oblock_t oblock, dm_cblock_t cblock)
 590 {
 591         if (test_and_clear_bit(from_cblock(cblock), cache->dirty_bitset)) {
 592                 policy_clear_dirty(cache->policy, oblock);
 593                 if (atomic_dec_return(&cache->nr_dirty) == 0)
 594                         dm_table_event(cache->ti->table);
 595         }
 596 }
 597
 598 /*----------------------------------------------------------------*/
 599
 600 static bool block_size_is_power_of_two(struct cache *cache)
 601 {
 602         return cache->sectors_per_block_shift >= 0;
 603 }
 604
 605 /* gcc on ARM generates spurious references to __udivdi3 and __umoddi3 */
 606 #if defined(CONFIG_ARM) && __GNUC__ == 4 && __GNUC_MINOR__ <= 6
 607 __always_inline
 608 #endif
 609 static dm_block_t block_div(dm_block_t b, uint32_t n)
 610 {
 611         do_div(b, n);
 612
 613         return b;
 614 }
 615
 616 static dm_block_t oblocks_per_dblock(struct cache *cache)
 617 {
 618         dm_block_t oblocks = cache->discard_block_size;
 619
 620         if (block_size_is_power_of_two(cache))
 621                 oblocks >>= cache->sectors_per_block_shift;
 622         else
 623                 oblocks = block_div(oblocks, cache->sectors_per_block);
 624
 625         return oblocks;
 626 }
 627
 628 static dm_dblock_t oblock_to_dblock(struct cache *cache, dm_oblock_t oblock)
 629 {
 630         return to_dblock(block_div(from_oblock(oblock),
 631                                    oblocks_per_dblock(cache)));
 632 }
 633
 634 static dm_oblock_t dblock_to_oblock(struct cache *cache, dm_dblock_t dblock)
 635 {
 636         return to_oblock(from_dblock(dblock) * oblocks_per_dblock(cache));
 637 }
 638
 639 static void set_discard(struct cache *cache, dm_dblock_t b)
 640 {
 641         unsigned long flags;
 642
 643         BUG_ON(from_dblock(b) >= from_dblock(cache->discard_nr_blocks));
 644         atomic_inc(&cache->stats.discard_count);
 645
 646         spin_lock_irqsave(&cache->lock, flags);
 647         set_bit(from_dblock(b), cache->discard_bitset);
 648         spin_unlock_irqrestore(&cache->lock, flags);
 649 }
 650
 651 static void clear_discard(struct cache *cache, dm_dblock_t b)
 652 {
 653         unsigned long flags;
 654
 655         spin_lock_irqsave(&cache->lock, flags);
 656         clear_bit(from_dblock(b), cache->discard_bitset);
 657         spin_unlock_irqrestore(&cache->lock, flags);
 658 }
 659
 660 static bool is_discarded(struct cache *cache, dm_dblock_t b)
 661 {
 662         int r;
 663         unsigned long flags;
 664
 665         spin_lock_irqsave(&cache->lock, flags);
 666         r = test_bit(from_dblock(b), cache->discard_bitset);
 667         spin_unlock_irqrestore(&cache->lock, flags);
 668
 669         return r;
 670 }
 671
 672 static bool is_discarded_oblock(struct cache *cache, dm_oblock_t b)
 673 {
 674         int r;
 675         unsigned long flags;
 676
 677         spin_lock_irqsave(&cache->lock, flags);
 678         r = test_bit(from_dblock(oblock_to_dblock(cache, b)),
 679                      cache->discard_bitset);
 680         spin_unlock_irqrestore(&cache->lock, flags);
 681
 682         return r;
 683 }
 684
 685 /*----------------------------------------------------------------*/
 686
 687 static void load_stats(struct cache *cache)
 688 {
 689         struct dm_cache_statistics stats;
 690
 691         dm_cache_metadata_get_stats(cache->cmd, &stats);
 692         atomic_set(&cache->stats.read_hit, stats.read_hits);
 693         atomic_set(&cache->stats.read_miss, stats.read_misses);
 694         atomic_set(&cache->stats.write_hit, stats.write_hits);
 695         atomic_set(&cache->stats.write_miss, stats.write_misses);
 696 }
 697
 698 static void save_stats(struct cache *cache)
 699 {
 700         struct dm_cache_statistics stats;
 701
 702         if (get_cache_mode(cache) >= CM_READ_ONLY)
 703                 return;
 704
 705         stats.read_hits = atomic_read(&cache->stats.read_hit);
 706         stats.read_misses = atomic_read(&cache->stats.read_miss);
 707         stats.write_hits = atomic_read(&cache->stats.write_hit);
 708         stats.write_misses = atomic_read(&cache->stats.write_miss);
 709
 710         dm_cache_metadata_set_stats(cache->cmd, &stats);
 711 }
 712
 713 /*----------------------------------------------------------------
 714  * Per bio data
 715  *--------------------------------------------------------------*/
 716
 717 /*
 718  * If using writeback, leave out struct per_bio_data's writethrough fields.
 719  */
 720 #define PB_DATA_SIZE_WB (offsetof(struct per_bio_data, cache))
 721 #define PB_DATA_SIZE_WT (sizeof(struct per_bio_data))
 722
 723 static bool writethrough_mode(struct cache_features *f)
 724 {
 725         return f->io_mode == CM_IO_WRITETHROUGH;
 726 }
 727
 728 static bool writeback_mode(struct cache_features *f)
 729 {
 730         return f->io_mode == CM_IO_WRITEBACK;
 731 }
 732
 733 static bool passthrough_mode(struct cache_features *f)
 734 {
 735         return f->io_mode == CM_IO_PASSTHROUGH;
 736 }
 737
 738 static size_t get_per_bio_data_size(struct cache *cache)
 739 {
 740         return writethrough_mode(&cache->features) ? PB_DATA_SIZE_WT : PB_DATA_SIZE_WB;
 741 }
 742
 743 static struct per_bio_data *get_per_bio_data(struct bio *bio, size_t data_size)
 744 {
 745         struct per_bio_data *pb = dm_per_bio_data(bio, data_size);
 746         BUG_ON(!pb);
 747         return pb;
 748 }
 749
 750 static struct per_bio_data *init_per_bio_data(struct bio *bio, size_t data_size)
 751 {
 752         struct per_bio_data *pb = get_per_bio_data(bio, data_size);
 753
 754         pb->tick = false;
 755         pb->req_nr = dm_bio_get_target_bio_nr(bio);
 756         pb->all_io_entry = NULL;
 757         pb->len = 0;
 758
 759         return pb;
 760 }
 761
 762 /*----------------------------------------------------------------
 763  * Remapping
 764  *--------------------------------------------------------------*/
 765 static void remap_to_origin(struct cache *cache, struct bio *bio)
 766 {
 767         bio->bi_bdev = cache->origin_dev->bdev;
 768 }
 769
 770 static void remap_to_cache(struct cache *cache, struct bio *bio,
 771                            dm_cblock_t cblock)
 772 {
 773         sector_t bi_sector = bio->bi_iter.bi_sector;
 774         sector_t block = from_cblock(cblock);
 775
 776         bio->bi_bdev = cache->cache_dev->bdev;
 777         if (!block_size_is_power_of_two(cache))
 778                 bio->bi_iter.bi_sector =
 779                         (block * cache->sectors_per_block) +
 780                         sector_div(bi_sector, cache->sectors_per_block);
 781         else
 782                 bio->bi_iter.bi_sector =
 783                         (block << cache->sectors_per_block_shift) |
 784                         (bi_sector & (cache->sectors_per_block - 1));
 785 }
 786
 787 static void check_if_tick_bio_needed(struct cache *cache, struct bio *bio)
 788 {
 789         unsigned long flags;
 790         size_t pb_data_size = get_per_bio_data_size(cache);
 791         struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
 792
 793         spin_lock_irqsave(&cache->lock, flags);
 794         if (cache->need_tick_bio &&
 795             !(bio->bi_rw & (REQ_FUA | REQ_FLUSH | REQ_DISCARD))) {
 796                 pb->tick = true;
 797                 cache->need_tick_bio = false;
 798         }
 799         spin_unlock_irqrestore(&cache->lock, flags);
 800 }
 801
 802 static void remap_to_origin_clear_discard(struct cache *cache, struct bio *bio,
 803                                   dm_oblock_t oblock)
 804 {
 805         check_if_tick_bio_needed(cache, bio);
 806         remap_to_origin(cache, bio);
 807         if (bio_data_dir(bio) == WRITE)
 808                 clear_discard(cache, oblock_to_dblock(cache, oblock));
 809 }
 810
 811 static void remap_to_cache_dirty(struct cache *cache, struct bio *bio,
 812                                  dm_oblock_t oblock, dm_cblock_t cblock)
 813 {
 814         check_if_tick_bio_needed(cache, bio);
 815         remap_to_cache(cache, bio, cblock);
 816         if (bio_data_dir(bio) == WRITE) {
 817                 set_dirty(cache, oblock, cblock);
 818                 clear_discard(cache, oblock_to_dblock(cache, oblock));
 819         }
 820 }
 821
 822 static dm_oblock_t get_bio_block(struct cache *cache, struct bio *bio)
 823 {
 824         sector_t block_nr = bio->bi_iter.bi_sector;
 825
 826         if (!block_size_is_power_of_two(cache))
 827                 (void) sector_div(block_nr, cache->sectors_per_block);
 828         else
 829                 block_nr >>= cache->sectors_per_block_shift;
 830
 831         return to_oblock(block_nr);
 832 }
 833
 834 static int bio_triggers_commit(struct cache *cache, struct bio *bio)
 835 {
 836         return bio->bi_rw & (REQ_FLUSH | REQ_FUA);
 837 }
 838
 839 /*
 840  * You must increment the deferred set whilst the prison cell is held.  To
 841  * encourage this, we ask for 'cell' to be passed in.
 842  */
 843 static void inc_ds(struct cache *cache, struct bio *bio,
 844                    struct dm_bio_prison_cell *cell)
 845 {
 846         size_t pb_data_size = get_per_bio_data_size(cache);
 847         struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
 848
 849         BUG_ON(!cell);
 850         BUG_ON(pb->all_io_entry);
 851
 852         pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
 853 }
 854
 855 static bool accountable_bio(struct cache *cache, struct bio *bio)
 856 {
 857         return ((bio->bi_bdev == cache->origin_dev->bdev) &&
 858                 !(bio->bi_rw & REQ_DISCARD));
 859 }
 860
 861 static void accounted_begin(struct cache *cache, struct bio *bio)
 862 {
 863         size_t pb_data_size = get_per_bio_data_size(cache);
 864         struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
 865
 866         if (accountable_bio(cache, bio)) {
 867                 pb->len = bio_sectors(bio);
 868                 iot_io_begin(&cache->origin_tracker, pb->len);
 869         }
 870 }
 871
 872 static void accounted_complete(struct cache *cache, struct bio *bio)
 873 {
 874         size_t pb_data_size = get_per_bio_data_size(cache);
 875         struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
 876
 877         iot_io_end(&cache->origin_tracker, pb->len);
 878 }
 879
 880 static void accounted_request(struct cache *cache, struct bio *bio)
 881 {
 882         accounted_begin(cache, bio);
 883         generic_make_request(bio);
 884 }
 885
 886 static void issue(struct cache *cache, struct bio *bio)
 887 {
 888         unsigned long flags;
 889
 890         if (!bio_triggers_commit(cache, bio)) {
 891                 accounted_request(cache, bio);
 892                 return;
 893         }
 894
 895         /*
 896          * Batch together any bios that trigger commits and then issue a
 897          * single commit for them in do_worker().
 898          */
 899         spin_lock_irqsave(&cache->lock, flags);
 900         cache->commit_requested = true;
 901         bio_list_add(&cache->deferred_flush_bios, bio);
 902         spin_unlock_irqrestore(&cache->lock, flags);
 903 }
 904
 905 static void inc_and_issue(struct cache *cache, struct bio *bio, struct dm_bio_prison_cell *cell)
 906 {
 907         inc_ds(cache, bio, cell);
 908         issue(cache, bio);
 909 }
 910
 911 static void defer_writethrough_bio(struct cache *cache, struct bio *bio)
 912 {
 913         unsigned long flags;
 914
 915         spin_lock_irqsave(&cache->lock, flags);
 916         bio_list_add(&cache->deferred_writethrough_bios, bio);
 917         spin_unlock_irqrestore(&cache->lock, flags);
 918
 919         wake_worker(cache);
 920 }
 921
 922 static void writethrough_endio(struct bio *bio, int err)
 923 {
 924         struct per_bio_data *pb = get_per_bio_data(bio, PB_DATA_SIZE_WT);
 925
 926         dm_unhook_bio(&pb->hook_info, bio);
 927
 928         if (err) {
 929                 bio_endio(bio, err);
 930                 return;
 931         }
 932
 933         dm_bio_restore(&pb->bio_details, bio);
 934         remap_to_cache(pb->cache, bio, pb->cblock);
 935
 936         /*
 937          * We can't issue this bio directly, since we're in interrupt
 938          * context.  So it gets put on a bio list for processing by the
 939          * worker thread.
 940          */
 941         defer_writethrough_bio(pb->cache, bio);
 942 }
 943
 944 /*
 945  * When running in writethrough mode we need to send writes to clean blocks
 946  * to both the cache and origin devices.  In future we'd like to clone the
 947  * bio and send them in parallel, but for now we're doing them in
 948  * series as this is easier.
 949  */
 950 static void remap_to_origin_then_cache(struct cache *cache, struct bio *bio,
 951                                        dm_oblock_t oblock, dm_cblock_t cblock)
 952 {
 953         struct per_bio_data *pb = get_per_bio_data(bio, PB_DATA_SIZE_WT);
 954
 955         pb->cache = cache;
 956         pb->cblock = cblock;
 957         dm_hook_bio(&pb->hook_info, bio, writethrough_endio, NULL);
 958         dm_bio_record(&pb->bio_details, bio);
 959
 960         remap_to_origin_clear_discard(pb->cache, bio, oblock);
 961 }
 962
 963 /*----------------------------------------------------------------
 964  * Failure modes
 965  *--------------------------------------------------------------*/
 966 static enum cache_metadata_mode get_cache_mode(struct cache *cache)
 967 {
 968         return cache->features.mode;
 969 }
 970
 971 static const char *cache_device_name(struct cache *cache)
 972 {
 973         return dm_device_name(dm_table_get_md(cache->ti->table));
 974 }
 975
 976 static void notify_mode_switch(struct cache *cache, enum cache_metadata_mode mode)
 977 {
 978         const char *descs[] = {
 979                 "write",
 980                 "read-only",
 981                 "fail"
 982         };
 983
 984         dm_table_event(cache->ti->table);
 985         DMINFO("%s: switching cache to %s mode",
 986                cache_device_name(cache), descs[(int)mode]);
 987 }
 988
 989 static void set_cache_mode(struct cache *cache, enum cache_metadata_mode new_mode)
 990 {
 991         bool needs_check = dm_cache_metadata_needs_check(cache->cmd);
 992         enum cache_metadata_mode old_mode = get_cache_mode(cache);
 993
 994         if (new_mode == CM_WRITE && needs_check) {
 995                 DMERR("%s: unable to switch cache to write mode until repaired.",
 996                       cache_device_name(cache));
 997                 if (old_mode != new_mode)
 998                         new_mode = old_mode;
 999                 else
1000                         new_mode = CM_READ_ONLY;
1001         }
1002
1003         /* Never move out of fail mode */
1004         if (old_mode == CM_FAIL)
1005                 new_mode = CM_FAIL;
1006
1007         switch (new_mode) {
1008         case CM_FAIL:
1009         case CM_READ_ONLY:
1010                 dm_cache_metadata_set_read_only(cache->cmd);
1011                 break;
1012
1013         case CM_WRITE:
1014                 dm_cache_metadata_set_read_write(cache->cmd);
1015                 break;
1016         }
1017
1018         cache->features.mode = new_mode;
1019
1020         if (new_mode != old_mode)
1021                 notify_mode_switch(cache, new_mode);
1022 }
1023
1024 static void abort_transaction(struct cache *cache)
1025 {
1026         const char *dev_name = cache_device_name(cache);
1027
1028         if (get_cache_mode(cache) >= CM_READ_ONLY)
1029                 return;
1030
1031         if (dm_cache_metadata_set_needs_check(cache->cmd)) {
1032                 DMERR("%s: failed to set 'needs_check' flag in metadata", dev_name);
1033                 set_cache_mode(cache, CM_FAIL);
1034         }
1035
1036         DMERR_LIMIT("%s: aborting current metadata transaction", dev_name);
1037         if (dm_cache_metadata_abort(cache->cmd)) {
1038                 DMERR("%s: failed to abort metadata transaction", dev_name);
1039                 set_cache_mode(cache, CM_FAIL);
1040         }
1041 }
1042
1043 static void metadata_operation_failed(struct cache *cache, const char *op, int r)
1044 {
1045         DMERR_LIMIT("%s: metadata operation '%s' failed: error = %d",
1046                     cache_device_name(cache), op, r);
1047         abort_transaction(cache);
1048         set_cache_mode(cache, CM_READ_ONLY);
1049 }
1050
1051 /*----------------------------------------------------------------
1052  * Migration processing
1053  *
1054  * Migration covers moving data from the origin device to the cache, or
1055  * vice versa.
1056  *--------------------------------------------------------------*/
1057 static void inc_io_migrations(struct cache *cache)
1058 {
1059         atomic_inc(&cache->nr_io_migrations);
1060 }
1061
1062 static void dec_io_migrations(struct cache *cache)
1063 {
1064         atomic_dec(&cache->nr_io_migrations);
1065 }
1066
1067 static void __cell_release(struct cache *cache, struct dm_bio_prison_cell *cell,
1068                            bool holder, struct bio_list *bios)
1069 {
1070         (holder ? dm_cell_release : dm_cell_release_no_holder)
1071                 (cache->prison, cell, bios);
1072         free_prison_cell(cache, cell);
1073 }
1074
1075 static bool discard_or_flush(struct bio *bio)
1076 {
1077         return bio->bi_rw & (REQ_FLUSH | REQ_FUA | REQ_DISCARD);
1078 }
1079
1080 static void __cell_defer(struct cache *cache, struct dm_bio_prison_cell *cell)
1081 {
1082         if (discard_or_flush(cell->holder))
1083                 /*
1084                  * We have to handle these bios
1085                  * individually.
1086                  */
1087                 __cell_release(cache, cell, true, &cache->deferred_bios);
1088
1089         else
1090                 list_add_tail(&cell->user_list, &cache->deferred_cells);
1091 }
1092
1093 static void cell_defer(struct cache *cache, struct dm_bio_prison_cell *cell, bool holder)
1094 {
1095         unsigned long flags;
1096
1097         if (!holder && dm_cell_promote_or_release(cache->prison, cell)) {
1098                 /*
1099                  * There was no prisoner to promote to holder, the
1100                  * cell has been released.
1101                  */
1102                 free_prison_cell(cache, cell);
1103                 return;
1104         }
1105
1106         spin_lock_irqsave(&cache->lock, flags);
1107         __cell_defer(cache, cell);
1108         spin_unlock_irqrestore(&cache->lock, flags);
1109
1110         wake_worker(cache);
1111 }
1112
1113 static void cell_error_with_code(struct cache *cache, struct dm_bio_prison_cell *cell, int err)
1114 {
1115         dm_cell_error(cache->prison, cell, err);
1116         dm_bio_prison_free_cell(cache->prison, cell);
1117 }
1118
1119 static void cell_requeue(struct cache *cache, struct dm_bio_prison_cell *cell)
1120 {
1121         cell_error_with_code(cache, cell, DM_ENDIO_REQUEUE);
1122 }
1123
1124 static void free_io_migration(struct dm_cache_migration *mg)
1125 {
1126         dec_io_migrations(mg->cache);
1127         free_migration(mg);
1128 }
1129
1130 static void migration_failure(struct dm_cache_migration *mg)
1131 {
1132         struct cache *cache = mg->cache;
1133         const char *dev_name = cache_device_name(cache);
1134
1135         if (mg->writeback) {
1136                 DMERR_LIMIT("%s: writeback failed; couldn't copy block", dev_name);
1137                 set_dirty(cache, mg->old_oblock, mg->cblock);
1138                 cell_defer(cache, mg->old_ocell, false);
1139
1140         } else if (mg->demote) {
1141                 DMERR_LIMIT("%s: demotion failed; couldn't copy block", dev_name);
1142                 policy_force_mapping(cache->policy, mg->new_oblock, mg->old_oblock);
1143
1144                 cell_defer(cache, mg->old_ocell, mg->promote ? false : true);
1145                 if (mg->promote)
1146                         cell_defer(cache, mg->new_ocell, true);
1147         } else {
1148                 DMERR_LIMIT("%s: promotion failed; couldn't copy block", dev_name);
1149                 policy_remove_mapping(cache->policy, mg->new_oblock);
1150                 cell_defer(cache, mg->new_ocell, true);
1151         }
1152
1153         free_io_migration(mg);
1154 }
1155
1156 static void migration_success_pre_commit(struct dm_cache_migration *mg)
1157 {
1158         int r;
1159         unsigned long flags;
1160         struct cache *cache = mg->cache;
1161
1162         if (mg->writeback) {
1163                 clear_dirty(cache, mg->old_oblock, mg->cblock);
1164                 cell_defer(cache, mg->old_ocell, false);
1165                 free_io_migration(mg);
1166                 return;
1167
1168         } else if (mg->demote) {
1169                 r = dm_cache_remove_mapping(cache->cmd, mg->cblock);
1170                 if (r) {
1171                         DMERR_LIMIT("%s: demotion failed; couldn't update on disk metadata",
1172                                     cache_device_name(cache));
1173                         metadata_operation_failed(cache, "dm_cache_remove_mapping", r);
1174                         policy_force_mapping(cache->policy, mg->new_oblock,
1175                                              mg->old_oblock);
1176                         if (mg->promote)
1177                                 cell_defer(cache, mg->new_ocell, true);
1178                         free_io_migration(mg);
1179                         return;
1180                 }
1181         } else {
1182                 r = dm_cache_insert_mapping(cache->cmd, mg->cblock, mg->new_oblock);
1183                 if (r) {
1184                         DMERR_LIMIT("%s: promotion failed; couldn't update on disk metadata",
1185                                     cache_device_name(cache));
1186                         metadata_operation_failed(cache, "dm_cache_insert_mapping", r);
1187                         policy_remove_mapping(cache->policy, mg->new_oblock);
1188                         free_io_migration(mg);
1189                         return;
1190                 }
1191         }
1192
1193         spin_lock_irqsave(&cache->lock, flags);
1194         list_add_tail(&mg->list, &cache->need_commit_migrations);
1195         cache->commit_requested = true;
1196         spin_unlock_irqrestore(&cache->lock, flags);
1197 }
1198
1199 static void migration_success_post_commit(struct dm_cache_migration *mg)
1200 {
1201         unsigned long flags;
1202         struct cache *cache = mg->cache;
1203
1204         if (mg->writeback) {
1205                 DMWARN_LIMIT("%s: writeback unexpectedly triggered commit",
1206                              cache_device_name(cache));
1207                 return;
1208
1209         } else if (mg->demote) {
1210                 cell_defer(cache, mg->old_ocell, mg->promote ? false : true);
1211
1212                 if (mg->promote) {
1213                         mg->demote = false;
1214
1215                         spin_lock_irqsave(&cache->lock, flags);
1216                         list_add_tail(&mg->list, &cache->quiesced_migrations);
1217                         spin_unlock_irqrestore(&cache->lock, flags);
1218
1219                 } else {
1220                         if (mg->invalidate)
1221                                 policy_remove_mapping(cache->policy, mg->old_oblock);
1222                         free_io_migration(mg);
1223                 }
1224
1225         } else {
1226                 if (mg->requeue_holder) {
1227                         clear_dirty(cache, mg->new_oblock, mg->cblock);
1228                         cell_defer(cache, mg->new_ocell, true);
1229                 } else {
1230                         /*
1231                          * The block was promoted via an overwrite, so it's dirty.
1232                          */
1233                         set_dirty(cache, mg->new_oblock, mg->cblock);
1234                         bio_endio(mg->new_ocell->holder, 0);
1235                         cell_defer(cache, mg->new_ocell, false);
1236                 }
1237                 free_io_migration(mg);
1238         }
1239 }
1240
1241 static void copy_complete(int read_err, unsigned long write_err, void *context)
1242 {
1243         unsigned long flags;
1244         struct dm_cache_migration *mg = (struct dm_cache_migration *) context;
1245         struct cache *cache = mg->cache;
1246
1247         if (read_err || write_err)
1248                 mg->err = true;
1249
1250         spin_lock_irqsave(&cache->lock, flags);
1251         list_add_tail(&mg->list, &cache->completed_migrations);
1252         spin_unlock_irqrestore(&cache->lock, flags);
1253
1254         wake_worker(cache);
1255 }
1256
1257 static void issue_copy(struct dm_cache_migration *mg)
1258 {
1259         int r;
1260         struct dm_io_region o_region, c_region;
1261         struct cache *cache = mg->cache;
1262         sector_t cblock = from_cblock(mg->cblock);
1263
1264         o_region.bdev = cache->origin_dev->bdev;
1265         o_region.count = cache->sectors_per_block;
1266
1267         c_region.bdev = cache->cache_dev->bdev;
1268         c_region.sector = cblock * cache->sectors_per_block;
1269         c_region.count = cache->sectors_per_block;
1270
1271         if (mg->writeback || mg->demote) {
1272                 /* demote */
1273                 o_region.sector = from_oblock(mg->old_oblock) * cache->sectors_per_block;
1274                 r = dm_kcopyd_copy(cache->copier, &c_region, 1, &o_region, 0, copy_complete, mg);
1275         } else {
1276                 /* promote */
1277                 o_region.sector = from_oblock(mg->new_oblock) * cache->sectors_per_block;
1278                 r = dm_kcopyd_copy(cache->copier, &o_region, 1, &c_region, 0, copy_complete, mg);
1279         }
1280
1281         if (r < 0) {
1282                 DMERR_LIMIT("%s: issuing migration failed", cache_device_name(cache));
1283                 migration_failure(mg);
1284         }
1285 }
1286
1287 static void overwrite_endio(struct bio *bio, int err)
1288 {
1289         struct dm_cache_migration *mg = bio->bi_private;
1290         struct cache *cache = mg->cache;
1291         size_t pb_data_size = get_per_bio_data_size(cache);
1292         struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
1293         unsigned long flags;
1294
1295         dm_unhook_bio(&pb->hook_info, bio);
1296
1297         if (err)
1298                 mg->err = true;
1299
1300         mg->requeue_holder = false;
1301
1302         spin_lock_irqsave(&cache->lock, flags);
1303         list_add_tail(&mg->list, &cache->completed_migrations);
1304         spin_unlock_irqrestore(&cache->lock, flags);
1305
1306         wake_worker(cache);
1307 }
1308
1309 static void issue_overwrite(struct dm_cache_migration *mg, struct bio *bio)
1310 {
1311         size_t pb_data_size = get_per_bio_data_size(mg->cache);
1312         struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
1313
1314         dm_hook_bio(&pb->hook_info, bio, overwrite_endio, mg);
1315         remap_to_cache_dirty(mg->cache, bio, mg->new_oblock, mg->cblock);
1316
1317         /*
1318          * No need to inc_ds() here, since the cell will be held for the
1319          * duration of the io.
1320          */
1321         accounted_request(mg->cache, bio);
1322 }
1323
1324 static bool bio_writes_complete_block(struct cache *cache, struct bio *bio)
1325 {
1326         return (bio_data_dir(bio) == WRITE) &&
1327                 (bio->bi_iter.bi_size == (cache->sectors_per_block << SECTOR_SHIFT));
1328 }
1329
1330 static void avoid_copy(struct dm_cache_migration *mg)
1331 {
1332         atomic_inc(&mg->cache->stats.copies_avoided);
1333         migration_success_pre_commit(mg);
1334 }
1335
1336 static void calc_discard_block_range(struct cache *cache, struct bio *bio,
1337                                      dm_dblock_t *b, dm_dblock_t *e)
1338 {
1339         sector_t sb = bio->bi_iter.bi_sector;
1340         sector_t se = bio_end_sector(bio);
1341
1342         *b = to_dblock(dm_sector_div_up(sb, cache->discard_block_size));
1343
1344         if (se - sb < cache->discard_block_size)
1345                 *e = *b;
1346         else
1347                 *e = to_dblock(block_div(se, cache->discard_block_size));
1348 }
1349
1350 static void issue_discard(struct dm_cache_migration *mg)
1351 {
1352         dm_dblock_t b, e;
1353         struct bio *bio = mg->new_ocell->holder;
1354
1355         calc_discard_block_range(mg->cache, bio, &b, &e);
1356         while (b != e) {
1357                 set_discard(mg->cache, b);
1358                 b = to_dblock(from_dblock(b) + 1);
1359         }
1360
1361         bio_endio(bio, 0);
1362         cell_defer(mg->cache, mg->new_ocell, false);
1363         free_migration(mg);
1364 }
1365
1366 static void issue_copy_or_discard(struct dm_cache_migration *mg)
1367 {
1368         bool avoid;
1369         struct cache *cache = mg->cache;
1370
1371         if (mg->discard) {
1372                 issue_discard(mg);
1373                 return;
1374         }
1375
1376         if (mg->writeback || mg->demote)
1377                 avoid = !is_dirty(cache, mg->cblock) ||
1378                         is_discarded_oblock(cache, mg->old_oblock);
1379         else {
1380                 struct bio *bio = mg->new_ocell->holder;
1381
1382                 avoid = is_discarded_oblock(cache, mg->new_oblock);
1383
1384                 if (writeback_mode(&cache->features) &&
1385                     !avoid && bio_writes_complete_block(cache, bio)) {
1386                         issue_overwrite(mg, bio);
1387                         return;
1388                 }
1389         }
1390
1391         avoid ? avoid_copy(mg) : issue_copy(mg);
1392 }
1393
1394 static void complete_migration(struct dm_cache_migration *mg)
1395 {
1396         if (mg->err)
1397                 migration_failure(mg);
1398         else
1399                 migration_success_pre_commit(mg);
1400 }
1401
1402 static void process_migrations(struct cache *cache, struct list_head *head,
1403                                void (*fn)(struct dm_cache_migration *))
1404 {
1405         unsigned long flags;
1406         struct list_head list;
1407         struct dm_cache_migration *mg, *tmp;
1408
1409         INIT_LIST_HEAD(&list);
1410         spin_lock_irqsave(&cache->lock, flags);
1411         list_splice_init(head, &list);
1412         spin_unlock_irqrestore(&cache->lock, flags);
1413
1414         list_for_each_entry_safe(mg, tmp, &list, list)
1415                 fn(mg);
1416 }
1417
1418 static void __queue_quiesced_migration(struct dm_cache_migration *mg)
1419 {
1420         list_add_tail(&mg->list, &mg->cache->quiesced_migrations);
1421 }
1422
1423 static void queue_quiesced_migration(struct dm_cache_migration *mg)
1424 {
1425         unsigned long flags;
1426         struct cache *cache = mg->cache;
1427
1428         spin_lock_irqsave(&cache->lock, flags);
1429         __queue_quiesced_migration(mg);
1430         spin_unlock_irqrestore(&cache->lock, flags);
1431
1432         wake_worker(cache);
1433 }
1434
1435 static void queue_quiesced_migrations(struct cache *cache, struct list_head *work)
1436 {
1437         unsigned long flags;
1438         struct dm_cache_migration *mg, *tmp;
1439
1440         spin_lock_irqsave(&cache->lock, flags);
1441         list_for_each_entry_safe(mg, tmp, work, list)
1442                 __queue_quiesced_migration(mg);
1443         spin_unlock_irqrestore(&cache->lock, flags);
1444
1445         wake_worker(cache);
1446 }
1447
1448 static void check_for_quiesced_migrations(struct cache *cache,
1449                                           struct per_bio_data *pb)
1450 {
1451         struct list_head work;
1452
1453         if (!pb->all_io_entry)
1454                 return;
1455
1456         INIT_LIST_HEAD(&work);
1457         dm_deferred_entry_dec(pb->all_io_entry, &work);
1458
1459         if (!list_empty(&work))
1460                 queue_quiesced_migrations(cache, &work);
1461 }
1462
1463 static void quiesce_migration(struct dm_cache_migration *mg)
1464 {
1465         if (!dm_deferred_set_add_work(mg->cache->all_io_ds, &mg->list))
1466                 queue_quiesced_migration(mg);
1467 }
1468
1469 static void promote(struct cache *cache, struct prealloc *structs,
1470                     dm_oblock_t oblock, dm_cblock_t cblock,
1471                     struct dm_bio_prison_cell *cell)
1472 {
1473         struct dm_cache_migration *mg = prealloc_get_migration(structs);
1474
1475         mg->err = false;
1476         mg->discard = false;
1477         mg->writeback = false;
1478         mg->demote = false;
1479         mg->promote = true;
1480         mg->requeue_holder = true;
1481         mg->invalidate = false;
1482         mg->cache = cache;
1483         mg->new_oblock = oblock;
1484         mg->cblock = cblock;
1485         mg->old_ocell = NULL;
1486         mg->new_ocell = cell;
1487         mg->start_jiffies = jiffies;
1488
1489         inc_io_migrations(cache);
1490         quiesce_migration(mg);
1491 }
1492
1493 static void writeback(struct cache *cache, struct prealloc *structs,
1494                       dm_oblock_t oblock, dm_cblock_t cblock,
1495                       struct dm_bio_prison_cell *cell)
1496 {
1497         struct dm_cache_migration *mg = prealloc_get_migration(structs);
1498
1499         mg->err = false;
1500         mg->discard = false;
1501         mg->writeback = true;
1502         mg->demote = false;
1503         mg->promote = false;
1504         mg->requeue_holder = true;
1505         mg->invalidate = false;
1506         mg->cache = cache;
1507         mg->old_oblock = oblock;
1508         mg->cblock = cblock;
1509         mg->old_ocell = cell;
1510         mg->new_ocell = NULL;
1511         mg->start_jiffies = jiffies;
1512
1513         inc_io_migrations(cache);
1514         quiesce_migration(mg);
1515 }
1516
1517 static void demote_then_promote(struct cache *cache, struct prealloc *structs,
1518                                 dm_oblock_t old_oblock, dm_oblock_t new_oblock,
1519                                 dm_cblock_t cblock,
1520                                 struct dm_bio_prison_cell *old_ocell,
1521                                 struct dm_bio_prison_cell *new_ocell)
1522 {
1523         struct dm_cache_migration *mg = prealloc_get_migration(structs);
1524
1525         mg->err = false;
1526         mg->discard = false;
1527         mg->writeback = false;
1528         mg->demote = true;
1529         mg->promote = true;
1530         mg->requeue_holder = true;
1531         mg->invalidate = false;
1532         mg->cache = cache;
1533         mg->old_oblock = old_oblock;
1534         mg->new_oblock = new_oblock;
1535         mg->cblock = cblock;
1536         mg->old_ocell = old_ocell;
1537         mg->new_ocell = new_ocell;
1538         mg->start_jiffies = jiffies;
1539
1540         inc_io_migrations(cache);
1541         quiesce_migration(mg);
1542 }
1543
1544 /*
1545  * Invalidate a cache entry.  No writeback occurs; any changes in the cache
1546  * block are thrown away.
1547  */
1548 static void invalidate(struct cache *cache, struct prealloc *structs,
1549                        dm_oblock_t oblock, dm_cblock_t cblock,
1550                        struct dm_bio_prison_cell *cell)
1551 {
1552         struct dm_cache_migration *mg = prealloc_get_migration(structs);
1553
1554         mg->err = false;
1555         mg->discard = false;
1556         mg->writeback = false;
1557         mg->demote = true;
1558         mg->promote = false;
1559         mg->requeue_holder = true;
1560         mg->invalidate = true;
1561         mg->cache = cache;
1562         mg->old_oblock = oblock;
1563         mg->cblock = cblock;
1564         mg->old_ocell = cell;
1565         mg->new_ocell = NULL;
1566         mg->start_jiffies = jiffies;
1567
1568         inc_io_migrations(cache);
1569         quiesce_migration(mg);
1570 }
1571
1572 static void discard(struct cache *cache, struct prealloc *structs,
1573                     struct dm_bio_prison_cell *cell)
1574 {
1575         struct dm_cache_migration *mg = prealloc_get_migration(structs);
1576
1577         mg->err = false;
1578         mg->discard = true;
1579         mg->writeback = false;
1580         mg->demote = false;
1581         mg->promote = false;
1582         mg->requeue_holder = false;
1583         mg->invalidate = false;
1584         mg->cache = cache;
1585         mg->old_ocell = NULL;
1586         mg->new_ocell = cell;
1587         mg->start_jiffies = jiffies;
1588
1589         quiesce_migration(mg);
1590 }
1591
1592 /*----------------------------------------------------------------
1593  * bio processing
1594  *--------------------------------------------------------------*/
1595 static void defer_bio(struct cache *cache, struct bio *bio)
1596 {
1597         unsigned long flags;
1598
1599         spin_lock_irqsave(&cache->lock, flags);
1600         bio_list_add(&cache->deferred_bios, bio);
1601         spin_unlock_irqrestore(&cache->lock, flags);
1602
1603         wake_worker(cache);
1604 }
1605
1606 static void process_flush_bio(struct cache *cache, struct bio *bio)
1607 {
1608         size_t pb_data_size = get_per_bio_data_size(cache);
1609         struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
1610
1611         BUG_ON(bio->bi_iter.bi_size);
1612         if (!pb->req_nr)
1613                 remap_to_origin(cache, bio);
1614         else
1615                 remap_to_cache(cache, bio, 0);
1616
1617         /*
1618          * REQ_FLUSH is not directed at any particular block so we don't
1619          * need to inc_ds().  REQ_FUA's are split into a write + REQ_FLUSH
1620          * by dm-core.
1621          */
1622         issue(cache, bio);
1623 }
1624
1625 static void process_discard_bio(struct cache *cache, struct prealloc *structs,
1626                                 struct bio *bio)
1627 {
1628         int r;
1629         dm_dblock_t b, e;
1630         struct dm_bio_prison_cell *cell_prealloc, *new_ocell;
1631
1632         calc_discard_block_range(cache, bio, &b, &e);
1633         if (b == e) {
1634                 bio_endio(bio, 0);
1635                 return;
1636         }
1637
1638         cell_prealloc = prealloc_get_cell(structs);
1639         r = bio_detain_range(cache, dblock_to_oblock(cache, b), dblock_to_oblock(cache, e), bio, cell_prealloc,
1640                              (cell_free_fn) prealloc_put_cell,
1641                              structs, &new_ocell);
1642         if (r > 0)
1643                 return;
1644
1645         discard(cache, structs, new_ocell);
1646 }
1647
1648 static bool spare_migration_bandwidth(struct cache *cache)
1649 {
1650         sector_t current_volume = (atomic_read(&cache->nr_io_migrations) + 1) *
1651                 cache->sectors_per_block;
1652         return current_volume < cache->migration_threshold;
1653 }
1654
1655 static 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
1661 static 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
1669 struct inc_detail {
1670         struct cache *cache;
1671         struct bio_list bios_for_issue;
1672         struct bio_list unhandled_bios;
1673         bool any_writes;
1674 };
1675
1676 static void inc_fn(void *context, struct dm_bio_prison_cell *cell)
1677 {
1678         struct bio *bio;
1679         struct inc_detail *detail = context;
1680         struct cache *cache = detail->cache;
1681
1682         inc_ds(cache, cell->holder, cell);
1683         if (bio_data_dir(cell->holder) == WRITE)
1684                 detail->any_writes = true;
1685
1686         while ((bio = bio_list_pop(&cell->bios))) {
1687                 if (discard_or_flush(bio)) {
1688                         bio_list_add(&detail->unhandled_bios, bio);
1689                         continue;
1690                 }
1691
1692                 if (bio_data_dir(bio) == WRITE)
1693                         detail->any_writes = true;
1694
1695                 bio_list_add(&detail->bios_for_issue, bio);
1696                 inc_ds(cache, bio, cell);
1697         }
1698 }
1699
1700 // FIXME: refactor these two
1701 static void remap_cell_to_origin_clear_discard(struct cache *cache,
1702                                                struct dm_bio_prison_cell *cell,
1703                                                dm_oblock_t oblock, bool issue_holder)
1704 {
1705         struct bio *bio;
1706         unsigned long flags;
1707         struct inc_detail detail;
1708
1709         detail.cache = cache;
1710         bio_list_init(&detail.bios_for_issue);
1711         bio_list_init(&detail.unhandled_bios);
1712         detail.any_writes = false;
1713
1714         spin_lock_irqsave(&cache->lock, flags);
1715         dm_cell_visit_release(cache->prison, inc_fn, &detail, cell);
1716         bio_list_merge(&cache->deferred_bios, &detail.unhandled_bios);
1717         spin_unlock_irqrestore(&cache->lock, flags);
1718
1719         remap_to_origin(cache, cell->holder);
1720         if (issue_holder)
1721                 issue(cache, cell->holder);
1722         else
1723                 accounted_begin(cache, cell->holder);
1724
1725         if (detail.any_writes)
1726                 clear_discard(cache, oblock_to_dblock(cache, oblock));
1727
1728         while ((bio = bio_list_pop(&detail.bios_for_issue))) {
1729                 remap_to_origin(cache, bio);
1730                 issue(cache, bio);
1731         }
1732 }
1733
1734 static void remap_cell_to_cache_dirty(struct cache *cache, struct dm_bio_prison_cell *cell,
1735                                       dm_oblock_t oblock, dm_cblock_t cblock, bool issue_holder)
1736 {
1737         struct bio *bio;
1738         unsigned long flags;
1739         struct inc_detail detail;
1740
1741         detail.cache = cache;
1742         bio_list_init(&detail.bios_for_issue);
1743         bio_list_init(&detail.unhandled_bios);
1744         detail.any_writes = false;
1745
1746         spin_lock_irqsave(&cache->lock, flags);
1747         dm_cell_visit_release(cache->prison, inc_fn, &detail, cell);
1748         bio_list_merge(&cache->deferred_bios, &detail.unhandled_bios);
1749         spin_unlock_irqrestore(&cache->lock, flags);
1750
1751         remap_to_cache(cache, cell->holder, cblock);
1752         if (issue_holder)
1753                 issue(cache, cell->holder);
1754         else
1755                 accounted_begin(cache, cell->holder);
1756
1757         if (detail.any_writes) {
1758                 set_dirty(cache, oblock, cblock);
1759                 clear_discard(cache, oblock_to_dblock(cache, oblock));
1760         }
1761
1762         while ((bio = bio_list_pop(&detail.bios_for_issue))) {
1763                 remap_to_cache(cache, bio, cblock);
1764                 issue(cache, bio);
1765         }
1766 }
1767
1768 /*----------------------------------------------------------------*/
1769
1770 struct old_oblock_lock {
1771         struct policy_locker locker;
1772         struct cache *cache;
1773         struct prealloc *structs;
1774         struct dm_bio_prison_cell *cell;
1775 };
1776
1777 static int null_locker(struct policy_locker *locker, dm_oblock_t b)
1778 {
1779         /* This should never be called */
1780         BUG();
1781         return 0;
1782 }
1783
1784 static int cell_locker(struct policy_locker *locker, dm_oblock_t b)
1785 {
1786         struct old_oblock_lock *l = container_of(locker, struct old_oblock_lock, locker);
1787         struct dm_bio_prison_cell *cell_prealloc = prealloc_get_cell(l->structs);
1788
1789         return bio_detain(l->cache, b, NULL, cell_prealloc,
1790                           (cell_free_fn) prealloc_put_cell,
1791                           l->structs, &l->cell);
1792 }
1793
1794 static void process_cell(struct cache *cache, struct prealloc *structs,
1795                          struct dm_bio_prison_cell *new_ocell)
1796 {
1797         int r;
1798         bool release_cell = true;
1799         struct bio *bio = new_ocell->holder;
1800         dm_oblock_t block = get_bio_block(cache, bio);
1801         struct policy_result lookup_result;
1802         bool passthrough = passthrough_mode(&cache->features);
1803         bool fast_promotion, can_migrate;
1804         struct old_oblock_lock ool;
1805
1806         fast_promotion = is_discarded_oblock(cache, block) || bio_writes_complete_block(cache, bio);
1807         can_migrate = !passthrough && (fast_promotion || spare_migration_bandwidth(cache));
1808
1809         ool.locker.fn = cell_locker;
1810         ool.cache = cache;
1811         ool.structs = structs;
1812         ool.cell = NULL;
1813         r = policy_map(cache->policy, block, true, can_migrate, fast_promotion,
1814                        bio, &ool.locker, &lookup_result);
1815
1816         if (r == -EWOULDBLOCK)
1817                 /* migration has been denied */
1818                 lookup_result.op = POLICY_MISS;
1819
1820         switch (lookup_result.op) {
1821         case POLICY_HIT:
1822                 if (passthrough) {
1823                         inc_miss_counter(cache, bio);
1824
1825                         /*
1826                          * Passthrough always maps to the origin,
1827                          * invalidating any cache blocks that are written
1828                          * to.
1829                          */
1830
1831                         if (bio_data_dir(bio) == WRITE) {
1832                                 atomic_inc(&cache->stats.demotion);
1833                                 invalidate(cache, structs, block, lookup_result.cblock, new_ocell);
1834                                 release_cell = false;
1835
1836                         } else {
1837                                 /* FIXME: factor out issue_origin() */
1838                                 remap_to_origin_clear_discard(cache, bio, block);
1839                                 inc_and_issue(cache, bio, new_ocell);
1840                         }
1841                 } else {
1842                         inc_hit_counter(cache, bio);
1843
1844                         if (bio_data_dir(bio) == WRITE &&
1845                             writethrough_mode(&cache->features) &&
1846                             !is_dirty(cache, lookup_result.cblock)) {
1847                                 remap_to_origin_then_cache(cache, bio, block, lookup_result.cblock);
1848                                 inc_and_issue(cache, bio, new_ocell);
1849
1850                         } else {
1851                                 remap_cell_to_cache_dirty(cache, new_ocell, block, lookup_result.cblock, true);
1852                                 release_cell = false;
1853                         }
1854                 }
1855
1856                 break;
1857
1858         case POLICY_MISS:
1859                 inc_miss_counter(cache, bio);
1860                 remap_cell_to_origin_clear_discard(cache, new_ocell, block, true);
1861                 release_cell = false;
1862                 break;
1863
1864         case POLICY_NEW:
1865                 atomic_inc(&cache->stats.promotion);
1866                 promote(cache, structs, block, lookup_result.cblock, new_ocell);
1867                 release_cell = false;
1868                 break;
1869
1870         case POLICY_REPLACE:
1871                 atomic_inc(&cache->stats.demotion);
1872                 atomic_inc(&cache->stats.promotion);
1873                 demote_then_promote(cache, structs, lookup_result.old_oblock,
1874                                     block, lookup_result.cblock,
1875                                     ool.cell, new_ocell);
1876                 release_cell = false;
1877                 break;
1878
1879         default:
1880                 DMERR_LIMIT("%s: %s: erroring bio, unknown policy op: %u",
1881                             cache_device_name(cache), __func__,
1882                             (unsigned) lookup_result.op);
1883                 bio_io_error(bio);
1884         }
1885
1886         if (release_cell)
1887                 cell_defer(cache, new_ocell, false);
1888 }
1889
1890 static void process_bio(struct cache *cache, struct prealloc *structs,
1891                         struct bio *bio)
1892 {
1893         int r;
1894         dm_oblock_t block = get_bio_block(cache, bio);
1895         struct dm_bio_prison_cell *cell_prealloc, *new_ocell;
1896
1897         /*
1898          * Check to see if that block is currently migrating.
1899          */
1900         cell_prealloc = prealloc_get_cell(structs);
1901         r = bio_detain(cache, block, bio, cell_prealloc,
1902                        (cell_free_fn) prealloc_put_cell,
1903                        structs, &new_ocell);
1904         if (r > 0)
1905                 return;
1906
1907         process_cell(cache, structs, new_ocell);
1908 }
1909
1910 static int need_commit_due_to_time(struct cache *cache)
1911 {
1912         return jiffies < cache->last_commit_jiffies ||
1913                jiffies > cache->last_commit_jiffies + COMMIT_PERIOD;
1914 }
1915
1916 /*
1917  * A non-zero return indicates read_only or fail_io mode.
1918  */
1919 static int commit(struct cache *cache, bool clean_shutdown)
1920 {
1921         int r;
1922
1923         if (get_cache_mode(cache) >= CM_READ_ONLY)
1924                 return -EINVAL;
1925
1926         atomic_inc(&cache->stats.commit_count);
1927         r = dm_cache_commit(cache->cmd, clean_shutdown);
1928         if (r)
1929                 metadata_operation_failed(cache, "dm_cache_commit", r);
1930
1931         return r;
1932 }
1933
1934 static int commit_if_needed(struct cache *cache)
1935 {
1936         int r = 0;
1937
1938         if ((cache->commit_requested || need_commit_due_to_time(cache)) &&
1939             dm_cache_changed_this_transaction(cache->cmd)) {
1940                 r = commit(cache, false);
1941                 cache->commit_requested = false;
1942                 cache->last_commit_jiffies = jiffies;
1943         }
1944
1945         return r;
1946 }
1947
1948 static void process_deferred_bios(struct cache *cache)
1949 {
1950         bool prealloc_used = false;
1951         unsigned long flags;
1952         struct bio_list bios;
1953         struct bio *bio;
1954         struct prealloc structs;
1955
1956         memset(&structs, 0, sizeof(structs));
1957         bio_list_init(&bios);
1958
1959         spin_lock_irqsave(&cache->lock, flags);
1960         bio_list_merge(&bios, &cache->deferred_bios);
1961         bio_list_init(&cache->deferred_bios);
1962         spin_unlock_irqrestore(&cache->lock, flags);
1963
1964         while (!bio_list_empty(&bios)) {
1965                 /*
1966                  * If we've got no free migration structs, and processing
1967                  * this bio might require one, we pause until there are some
1968                  * prepared mappings to process.
1969                  */
1970                 if (prealloc_data_structs(cache, &structs)) {
1971                         spin_lock_irqsave(&cache->lock, flags);
1972                         bio_list_merge(&cache->deferred_bios, &bios);
1973                         spin_unlock_irqrestore(&cache->lock, flags);
1974                         break;
1975                 }
1976
1977                 bio = bio_list_pop(&bios);
1978
1979                 if (bio->bi_rw & REQ_FLUSH)
1980                         process_flush_bio(cache, bio);
1981                 else if (bio->bi_rw & REQ_DISCARD)
1982                         process_discard_bio(cache, &structs, bio);
1983                 else
1984                         process_bio(cache, &structs, bio);
1985                 prealloc_used = true;
1986         }
1987
1988         if (prealloc_used)
1989                 prealloc_free_structs(cache, &structs);
1990 }
1991
1992 static void process_deferred_cells(struct cache *cache)
1993 {
1994         bool prealloc_used = false;
1995         unsigned long flags;
1996         struct dm_bio_prison_cell *cell, *tmp;
1997         struct list_head cells;
1998         struct prealloc structs;
1999
2000         memset(&structs, 0, sizeof(structs));
2001
2002         INIT_LIST_HEAD(&cells);
2003
2004         spin_lock_irqsave(&cache->lock, flags);
2005         list_splice_init(&cache->deferred_cells, &cells);
2006         spin_unlock_irqrestore(&cache->lock, flags);
2007
2008         list_for_each_entry_safe(cell, tmp, &cells, user_list) {
2009                 /*
2010                  * If we've got no free migration structs, and processing
2011                  * this bio might require one, we pause until there are some
2012                  * prepared mappings to process.
2013                  */
2014                 if (prealloc_data_structs(cache, &structs)) {
2015                         spin_lock_irqsave(&cache->lock, flags);
2016                         list_splice(&cells, &cache->deferred_cells);
2017                         spin_unlock_irqrestore(&cache->lock, flags);
2018                         break;
2019                 }
2020
2021                 process_cell(cache, &structs, cell);
2022                 prealloc_used = true;
2023         }
2024
2025         if (prealloc_used)
2026                 prealloc_free_structs(cache, &structs);
2027 }
2028
2029 static void process_deferred_flush_bios(struct cache *cache, bool submit_bios)
2030 {
2031         unsigned long flags;
2032         struct bio_list bios;
2033         struct bio *bio;
2034
2035         bio_list_init(&bios);
2036
2037         spin_lock_irqsave(&cache->lock, flags);
2038         bio_list_merge(&bios, &cache->deferred_flush_bios);
2039         bio_list_init(&cache->deferred_flush_bios);
2040         spin_unlock_irqrestore(&cache->lock, flags);
2041
2042         /*
2043          * These bios have already been through inc_ds()
2044          */
2045         while ((bio = bio_list_pop(&bios)))
2046                 submit_bios ? accounted_request(cache, bio) : bio_io_error(bio);
2047 }
2048
2049 static void process_deferred_writethrough_bios(struct cache *cache)
2050 {
2051         unsigned long flags;
2052         struct bio_list bios;
2053         struct bio *bio;
2054
2055         bio_list_init(&bios);
2056
2057         spin_lock_irqsave(&cache->lock, flags);
2058         bio_list_merge(&bios, &cache->deferred_writethrough_bios);
2059         bio_list_init(&cache->deferred_writethrough_bios);
2060         spin_unlock_irqrestore(&cache->lock, flags);
2061
2062         /*
2063          * These bios have already been through inc_ds()
2064          */
2065         while ((bio = bio_list_pop(&bios)))
2066                 accounted_request(cache, bio);
2067 }
2068
2069 static void writeback_some_dirty_blocks(struct cache *cache)
2070 {
2071         bool prealloc_used = false;
2072         dm_oblock_t oblock;
2073         dm_cblock_t cblock;
2074         struct prealloc structs;
2075         struct dm_bio_prison_cell *old_ocell;
2076         bool busy = !iot_idle_for(&cache->origin_tracker, HZ);
2077
2078         memset(&structs, 0, sizeof(structs));
2079
2080         while (spare_migration_bandwidth(cache)) {
2081                 if (policy_writeback_work(cache->policy, &oblock, &cblock, busy))
2082                         break; /* no work to do */
2083
2084                 if (prealloc_data_structs(cache, &structs) ||
2085                     get_cell(cache, oblock, &structs, &old_ocell)) {
2086                         policy_set_dirty(cache->policy, oblock);
2087                         break;
2088                 }
2089
2090                 writeback(cache, &structs, oblock, cblock, old_ocell);
2091                 prealloc_used = true;
2092         }
2093
2094         if (prealloc_used)
2095                 prealloc_free_structs(cache, &structs);
2096 }
2097
2098 /*----------------------------------------------------------------
2099  * Invalidations.
2100  * Dropping something from the cache *without* writing back.
2101  *--------------------------------------------------------------*/
2102
2103 static void process_invalidation_request(struct cache *cache, struct invalidation_request *req)
2104 {
2105         int r = 0;
2106         uint64_t begin = from_cblock(req->cblocks->begin);
2107         uint64_t end = from_cblock(req->cblocks->end);
2108
2109         while (begin != end) {
2110                 r = policy_remove_cblock(cache->policy, to_cblock(begin));
2111                 if (!r) {
2112                         r = dm_cache_remove_mapping(cache->cmd, to_cblock(begin));
2113                         if (r) {
2114                                 metadata_operation_failed(cache, "dm_cache_remove_mapping", r);
2115                                 break;
2116                         }
2117
2118                 } else if (r == -ENODATA) {
2119                         /* harmless, already unmapped */
2120                         r = 0;
2121
2122                 } else {
2123                         DMERR("%s: policy_remove_cblock failed", cache_device_name(cache));
2124                         break;
2125                 }
2126
2127                 begin++;
2128         }
2129
2130         cache->commit_requested = true;
2131
2132         req->err = r;
2133         atomic_set(&req->complete, 1);
2134
2135         wake_up(&req->result_wait);
2136 }
2137
2138 static void process_invalidation_requests(struct cache *cache)
2139 {
2140         struct list_head list;
2141         struct invalidation_request *req, *tmp;
2142
2143         INIT_LIST_HEAD(&list);
2144         spin_lock(&cache->invalidation_lock);
2145         list_splice_init(&cache->invalidation_requests, &list);
2146         spin_unlock(&cache->invalidation_lock);
2147
2148         list_for_each_entry_safe (req, tmp, &list, list)
2149                 process_invalidation_request(cache, req);
2150 }
2151
2152 /*----------------------------------------------------------------
2153  * Main worker loop
2154  *--------------------------------------------------------------*/
2155 static bool is_quiescing(struct cache *cache)
2156 {
2157         return atomic_read(&cache->quiescing);
2158 }
2159
2160 static void ack_quiescing(struct cache *cache)
2161 {
2162         if (is_quiescing(cache)) {
2163                 atomic_inc(&cache->quiescing_ack);
2164                 wake_up(&cache->quiescing_wait);
2165         }
2166 }
2167
2168 static void wait_for_quiescing_ack(struct cache *cache)
2169 {
2170         wait_event(cache->quiescing_wait, atomic_read(&cache->quiescing_ack));
2171 }
2172
2173 static void start_quiescing(struct cache *cache)
2174 {
2175         atomic_inc(&cache->quiescing);
2176         wait_for_quiescing_ack(cache);
2177 }
2178
2179 static void stop_quiescing(struct cache *cache)
2180 {
2181         atomic_set(&cache->quiescing, 0);
2182         atomic_set(&cache->quiescing_ack, 0);
2183 }
2184
2185 static void wait_for_migrations(struct cache *cache)
2186 {
2187         wait_event(cache->migration_wait, !atomic_read(&cache->nr_allocated_migrations));
2188 }
2189
2190 static void stop_worker(struct cache *cache)
2191 {
2192         cancel_delayed_work(&cache->waker);
2193         flush_workqueue(cache->wq);
2194 }
2195
2196 static void requeue_deferred_cells(struct cache *cache)
2197 {
2198         unsigned long flags;
2199         struct list_head cells;
2200         struct dm_bio_prison_cell *cell, *tmp;
2201
2202         INIT_LIST_HEAD(&cells);
2203         spin_lock_irqsave(&cache->lock, flags);
2204         list_splice_init(&cache->deferred_cells, &cells);
2205         spin_unlock_irqrestore(&cache->lock, flags);
2206
2207         list_for_each_entry_safe(cell, tmp, &cells, user_list)
2208                 cell_requeue(cache, cell);
2209 }
2210
2211 static void requeue_deferred_bios(struct cache *cache)
2212 {
2213         struct bio *bio;
2214         struct bio_list bios;
2215
2216         bio_list_init(&bios);
2217         bio_list_merge(&bios, &cache->deferred_bios);
2218         bio_list_init(&cache->deferred_bios);
2219
2220         while ((bio = bio_list_pop(&bios)))
2221                 bio_endio(bio, DM_ENDIO_REQUEUE);
2222 }
2223
2224 static int more_work(struct cache *cache)
2225 {
2226         if (is_quiescing(cache))
2227                 return !list_empty(&cache->quiesced_migrations) ||
2228                         !list_empty(&cache->completed_migrations) ||
2229                         !list_empty(&cache->need_commit_migrations);
2230         else
2231                 return !bio_list_empty(&cache->deferred_bios) ||
2232                         !list_empty(&cache->deferred_cells) ||
2233                         !bio_list_empty(&cache->deferred_flush_bios) ||
2234                         !bio_list_empty(&cache->deferred_writethrough_bios) ||
2235                         !list_empty(&cache->quiesced_migrations) ||
2236                         !list_empty(&cache->completed_migrations) ||
2237                         !list_empty(&cache->need_commit_migrations) ||
2238                         cache->invalidate;
2239 }
2240
2241 static void do_worker(struct work_struct *ws)
2242 {
2243         struct cache *cache = container_of(ws, struct cache, worker);
2244
2245         do {
2246                 if (!is_quiescing(cache)) {
2247                         writeback_some_dirty_blocks(cache);
2248                         process_deferred_writethrough_bios(cache);
2249                         process_deferred_bios(cache);
2250                         process_deferred_cells(cache);
2251                         process_invalidation_requests(cache);
2252                 }
2253
2254                 process_migrations(cache, &cache->quiesced_migrations, issue_copy_or_discard);
2255                 process_migrations(cache, &cache->completed_migrations, complete_migration);
2256
2257                 if (commit_if_needed(cache)) {
2258                         process_deferred_flush_bios(cache, false);
2259                         process_migrations(cache, &cache->need_commit_migrations, migration_failure);
2260                 } else {
2261                         process_deferred_flush_bios(cache, true);
2262                         process_migrations(cache, &cache->need_commit_migrations,
2263                                            migration_success_post_commit);
2264                 }
2265
2266                 ack_quiescing(cache);
2267
2268         } while (more_work(cache));
2269 }
2270
2271 /*
2272  * We want to commit periodically so that not too much
2273  * unwritten metadata builds up.
2274  */
2275 static void do_waker(struct work_struct *ws)
2276 {
2277         struct cache *cache = container_of(to_delayed_work(ws), struct cache, waker);
2278         policy_tick(cache->policy, true);
2279         wake_worker(cache);
2280         queue_delayed_work(cache->wq, &cache->waker, COMMIT_PERIOD);
2281 }
2282
2283 /*----------------------------------------------------------------*/
2284
2285 static int is_congested(struct dm_dev *dev, int bdi_bits)
2286 {
2287         struct request_queue *q = bdev_get_queue(dev->bdev);
2288         return bdi_congested(&q->backing_dev_info, bdi_bits);
2289 }
2290
2291 static int cache_is_congested(struct dm_target_callbacks *cb, int bdi_bits)
2292 {
2293         struct cache *cache = container_of(cb, struct cache, callbacks);
2294
2295         return is_congested(cache->origin_dev, bdi_bits) ||
2296                 is_congested(cache->cache_dev, bdi_bits);
2297 }
2298
2299 /*----------------------------------------------------------------
2300  * Target methods
2301  *--------------------------------------------------------------*/
2302
2303 /*
2304  * This function gets called on the error paths of the constructor, so we
2305  * have to cope with a partially initialised struct.
2306  */
2307 static void destroy(struct cache *cache)
2308 {
2309         unsigned i;
2310
2311         if (cache->migration_pool)
2312                 mempool_destroy(cache->migration_pool);
2313
2314         if (cache->all_io_ds)
2315                 dm_deferred_set_destroy(cache->all_io_ds);
2316
2317         if (cache->prison)
2318                 dm_bio_prison_destroy(cache->prison);
2319
2320         if (cache->wq)
2321                 destroy_workqueue(cache->wq);
2322
2323         if (cache->dirty_bitset)
2324                 free_bitset(cache->dirty_bitset);
2325
2326         if (cache->discard_bitset)
2327                 free_bitset(cache->discard_bitset);
2328
2329         if (cache->copier)
2330                 dm_kcopyd_client_destroy(cache->copier);
2331
2332         if (cache->cmd)
2333                 dm_cache_metadata_close(cache->cmd);
2334
2335         if (cache->metadata_dev)
2336                 dm_put_device(cache->ti, cache->metadata_dev);
2337
2338         if (cache->origin_dev)
2339                 dm_put_device(cache->ti, cache->origin_dev);
2340
2341         if (cache->cache_dev)
2342                 dm_put_device(cache->ti, cache->cache_dev);
2343
2344         if (cache->policy)
2345                 dm_cache_policy_destroy(cache->policy);
2346
2347         for (i = 0; i < cache->nr_ctr_args ; i++)
2348                 kfree(cache->ctr_args[i]);
2349         kfree(cache->ctr_args);
2350
2351         kfree(cache);
2352 }
2353
2354 static void cache_dtr(struct dm_target *ti)
2355 {
2356         struct cache *cache = ti->private;
2357
2358         destroy(cache);
2359 }
2360
2361 static sector_t get_dev_size(struct dm_dev *dev)
2362 {
2363         return i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT;
2364 }
2365
2366 /*----------------------------------------------------------------*/
2367
2368 /*
2369  * Construct a cache device mapping.
2370  *
2371  * cache <metadata dev> <cache dev> <origin dev> <block size>
2372  *       <#feature args> [<feature arg>]*
2373  *       <policy> <#policy args> [<policy arg>]*
2374  *
2375  * metadata dev    : fast device holding the persistent metadata
2376  * cache dev       : fast device holding cached data blocks
2377  * origin dev      : slow device holding original data blocks
2378  * block size      : cache unit size in sectors
2379  *
2380  * #feature args   : number of feature arguments passed
2381  * feature args    : writethrough.  (The default is writeback.)
2382  *
2383  * policy          : the replacement policy to use
2384  * #policy args    : an even number of policy arguments corresponding
2385  *                   to key/value pairs passed to the policy
2386  * policy args     : key/value pairs passed to the policy
2387  *                   E.g. 'sequential_threshold 1024'
2388  *                   See cache-policies.txt for details.
2389  *
2390  * Optional feature arguments are:
2391  *   writethrough  : write through caching that prohibits cache block
2392  *                   content from being different from origin block content.
2393  *                   Without this argument, the default behaviour is to write
2394  *                   back cache block contents later for performance reasons,
2395  *                   so they may differ from the corresponding origin blocks.
2396  */
2397 struct cache_args {
2398         struct dm_target *ti;
2399
2400         struct dm_dev *metadata_dev;
2401
2402         struct dm_dev *cache_dev;
2403         sector_t cache_sectors;
2404
2405         struct dm_dev *origin_dev;
2406         sector_t origin_sectors;
2407
2408         uint32_t block_size;
2409
2410         const char *policy_name;
2411         int policy_argc;
2412         const char **policy_argv;
2413
2414         struct cache_features features;
2415 };
2416
2417 static void destroy_cache_args(struct cache_args *ca)
2418 {
2419         if (ca->metadata_dev)
2420                 dm_put_device(ca->ti, ca->metadata_dev);
2421
2422         if (ca->cache_dev)
2423                 dm_put_device(ca->ti, ca->cache_dev);
2424
2425         if (ca->origin_dev)
2426                 dm_put_device(ca->ti, ca->origin_dev);
2427
2428         kfree(ca);
2429 }
2430
2431 static bool at_least_one_arg(struct dm_arg_set *as, char **error)
2432 {
2433         if (!as->argc) {
2434                 *error = "Insufficient args";
2435                 return false;
2436         }
2437
2438         return true;
2439 }
2440
2441 static int parse_metadata_dev(struct cache_args *ca, struct dm_arg_set *as,
2442                               char **error)
2443 {
2444         int r;
2445         sector_t metadata_dev_size;
2446         char b[BDEVNAME_SIZE];
2447
2448         if (!at_least_one_arg(as, error))
2449                 return -EINVAL;
2450
2451         r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
2452                           &ca->metadata_dev);
2453         if (r) {
2454                 *error = "Error opening metadata device";
2455                 return r;
2456         }
2457
2458         metadata_dev_size = get_dev_size(ca->metadata_dev);
2459         if (metadata_dev_size > DM_CACHE_METADATA_MAX_SECTORS_WARNING)
2460                 DMWARN("Metadata device %s is larger than %u sectors: excess space will not be used.",
2461                        bdevname(ca->metadata_dev->bdev, b), THIN_METADATA_MAX_SECTORS);
2462
2463         return 0;
2464 }
2465
2466 static int parse_cache_dev(struct cache_args *ca, struct dm_arg_set *as,
2467                            char **error)
2468 {
2469         int r;
2470
2471         if (!at_least_one_arg(as, error))
2472                 return -EINVAL;
2473
2474         r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
2475                           &ca->cache_dev);
2476         if (r) {
2477                 *error = "Error opening cache device";
2478                 return r;
2479         }
2480         ca->cache_sectors = get_dev_size(ca->cache_dev);
2481
2482         return 0;
2483 }
2484
2485 static int parse_origin_dev(struct cache_args *ca, struct dm_arg_set *as,
2486                             char **error)
2487 {
2488         int r;
2489
2490         if (!at_least_one_arg(as, error))
2491                 return -EINVAL;
2492
2493         r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
2494                           &ca->origin_dev);
2495         if (r) {
2496                 *error = "Error opening origin device";
2497                 return r;
2498         }
2499
2500         ca->origin_sectors = get_dev_size(ca->origin_dev);
2501         if (ca->ti->len > ca->origin_sectors) {
2502                 *error = "Device size larger than cached device";
2503                 return -EINVAL;
2504         }
2505
2506         return 0;
2507 }
2508
2509 static int parse_block_size(struct cache_args *ca, struct dm_arg_set *as,
2510                             char **error)
2511 {
2512         unsigned long block_size;
2513
2514         if (!at_least_one_arg(as, error))
2515                 return -EINVAL;
2516
2517         if (kstrtoul(dm_shift_arg(as), 10, &block_size) || !block_size ||
2518             block_size < DATA_DEV_BLOCK_SIZE_MIN_SECTORS ||
2519             block_size > DATA_DEV_BLOCK_SIZE_MAX_SECTORS ||
2520             block_size & (DATA_DEV_BLOCK_SIZE_MIN_SECTORS - 1)) {
2521                 *error = "Invalid data block size";
2522                 return -EINVAL;
2523         }
2524
2525         if (block_size > ca->cache_sectors) {
2526                 *error = "Data block size is larger than the cache device";
2527                 return -EINVAL;
2528         }
2529
2530         ca->block_size = block_size;
2531
2532         return 0;
2533 }
2534
2535 static void init_features(struct cache_features *cf)
2536 {
2537         cf->mode = CM_WRITE;
2538         cf->io_mode = CM_IO_WRITEBACK;
2539 }
2540
2541 static int parse_features(struct cache_args *ca, struct dm_arg_set *as,
2542                           char **error)
2543 {
2544         static struct dm_arg _args[] = {
2545                 {0, 1, "Invalid number of cache feature arguments"},
2546         };
2547
2548         int r;
2549         unsigned argc;
2550         const char *arg;
2551         struct cache_features *cf = &ca->features;
2552
2553         init_features(cf);
2554
2555         r = dm_read_arg_group(_args, as, &argc, error);
2556         if (r)
2557                 return -EINVAL;
2558
2559         while (argc--) {
2560                 arg = dm_shift_arg(as);
2561
2562                 if (!strcasecmp(arg, "writeback"))
2563                         cf->io_mode = CM_IO_WRITEBACK;
2564
2565                 else if (!strcasecmp(arg, "writethrough"))
2566                         cf->io_mode = CM_IO_WRITETHROUGH;
2567
2568                 else if (!strcasecmp(arg, "passthrough"))
2569                         cf->io_mode = CM_IO_PASSTHROUGH;
2570
2571                 else {
2572                         *error = "Unrecognised cache feature requested";
2573                         return -EINVAL;
2574                 }
2575         }
2576
2577         return 0;
2578 }
2579
2580 static int parse_policy(struct cache_args *ca, struct dm_arg_set *as,
2581                         char **error)
2582 {
2583         static struct dm_arg _args[] = {
2584                 {0, 1024, "Invalid number of policy arguments"},
2585         };
2586
2587         int r;
2588
2589         if (!at_least_one_arg(as, error))
2590                 return -EINVAL;
2591
2592         ca->policy_name = dm_shift_arg(as);
2593
2594         r = dm_read_arg_group(_args, as, &ca->policy_argc, error);
2595         if (r)
2596                 return -EINVAL;
2597
2598         ca->policy_argv = (const char **)as->argv;
2599         dm_consume_args(as, ca->policy_argc);
2600
2601         return 0;
2602 }
2603
2604 static int parse_cache_args(struct cache_args *ca, int argc, char **argv,
2605                             char **error)
2606 {
2607         int r;
2608         struct dm_arg_set as;
2609
2610         as.argc = argc;
2611         as.argv = argv;
2612
2613         r = parse_metadata_dev(ca, &as, error);
2614         if (r)
2615                 return r;
2616
2617         r = parse_cache_dev(ca, &as, error);
2618         if (r)
2619                 return r;
2620
2621         r = parse_origin_dev(ca, &as, error);
2622         if (r)
2623                 return r;
2624
2625         r = parse_block_size(ca, &as, error);
2626         if (r)
2627                 return r;
2628
2629         r = parse_features(ca, &as, error);
2630         if (r)
2631                 return r;
2632
2633         r = parse_policy(ca, &as, error);
2634         if (r)
2635                 return r;
2636
2637         return 0;
2638 }
2639
2640 /*----------------------------------------------------------------*/
2641
2642 static struct kmem_cache *migration_cache;
2643
2644 #define NOT_CORE_OPTION 1
2645
2646 static int process_config_option(struct cache *cache, const char *key, const char *value)
2647 {
2648         unsigned long tmp;
2649
2650         if (!strcasecmp(key, "migration_threshold")) {
2651                 if (kstrtoul(value, 10, &tmp))
2652                         return -EINVAL;
2653
2654                 cache->migration_threshold = tmp;
2655                 return 0;
2656         }
2657
2658         return NOT_CORE_OPTION;
2659 }
2660
2661 static int set_config_value(struct cache *cache, const char *key, const char *value)
2662 {
2663         int r = process_config_option(cache, key, value);
2664
2665         if (r == NOT_CORE_OPTION)
2666                 r = policy_set_config_value(cache->policy, key, value);
2667
2668         if (r)
2669                 DMWARN("bad config value for %s: %s", key, value);
2670
2671         return r;
2672 }
2673
2674 static int set_config_values(struct cache *cache, int argc, const char **argv)
2675 {
2676         int r = 0;
2677
2678         if (argc & 1) {
2679                 DMWARN("Odd number of policy arguments given but they should be <key> <value> pairs.");
2680                 return -EINVAL;
2681         }
2682
2683         while (argc) {
2684                 r = set_config_value(cache, argv[0], argv[1]);
2685                 if (r)
2686                         break;
2687
2688                 argc -= 2;
2689                 argv += 2;
2690         }
2691
2692         return r;
2693 }
2694
2695 static int create_cache_policy(struct cache *cache, struct cache_args *ca,
2696                                char **error)
2697 {
2698         struct dm_cache_policy *p = dm_cache_policy_create(ca->policy_name,
2699                                                            cache->cache_size,
2700                                                            cache->origin_sectors,
2701                                                            cache->sectors_per_block);
2702         if (IS_ERR(p)) {
2703                 *error = "Error creating cache's policy";
2704                 return PTR_ERR(p);
2705         }
2706         cache->policy = p;
2707
2708         return 0;
2709 }
2710
2711 /*
2712  * We want the discard block size to be at least the size of the cache
2713  * block size and have no more than 2^14 discard blocks across the origin.
2714  */
2715 #define MAX_DISCARD_BLOCKS (1 << 14)
2716
2717 static bool too_many_discard_blocks(sector_t discard_block_size,
2718                                     sector_t origin_size)
2719 {
2720         (void) sector_div(origin_size, discard_block_size);
2721
2722         return origin_size > MAX_DISCARD_BLOCKS;
2723 }
2724
2725 static sector_t calculate_discard_block_size(sector_t cache_block_size,
2726                                              sector_t origin_size)
2727 {
2728         sector_t discard_block_size = cache_block_size;
2729
2730         if (origin_size)
2731                 while (too_many_discard_blocks(discard_block_size, origin_size))
2732                         discard_block_size *= 2;
2733
2734         return discard_block_size;
2735 }
2736
2737 static void set_cache_size(struct cache *cache, dm_cblock_t size)
2738 {
2739         dm_block_t nr_blocks = from_cblock(size);
2740
2741         if (nr_blocks > (1 << 20) && cache->cache_size != size)
2742                 DMWARN_LIMIT("You have created a cache device with a lot of individual cache blocks (%llu)\n"
2743                              "All these mappings can consume a lot of kernel memory, and take some time to read/write.\n"
2744                              "Please consider increasing the cache block size to reduce the overall cache block count.",
2745                              (unsigned long long) nr_blocks);
2746
2747         cache->cache_size = size;
2748 }
2749
2750 #define DEFAULT_MIGRATION_THRESHOLD 2048
2751
2752 static int cache_create(struct cache_args *ca, struct cache **result)
2753 {
2754         int r = 0;
2755         char **error = &ca->ti->error;
2756         struct cache *cache;
2757         struct dm_target *ti = ca->ti;
2758         dm_block_t origin_blocks;
2759         struct dm_cache_metadata *cmd;
2760         bool may_format = ca->features.mode == CM_WRITE;
2761
2762         cache = kzalloc(sizeof(*cache), GFP_KERNEL);
2763         if (!cache)
2764                 return -ENOMEM;
2765
2766         cache->ti = ca->ti;
2767         ti->private = cache;
2768         ti->num_flush_bios = 2;
2769         ti->flush_supported = true;
2770
2771         ti->num_discard_bios = 1;
2772         ti->discards_supported = true;
2773         ti->discard_zeroes_data_unsupported = true;
2774         ti->split_discard_bios = false;
2775
2776         cache->features = ca->features;
2777         ti->per_bio_data_size = get_per_bio_data_size(cache);
2778
2779         cache->callbacks.congested_fn = cache_is_congested;
2780         dm_table_add_target_callbacks(ti->table, &cache->callbacks);
2781
2782         cache->metadata_dev = ca->metadata_dev;
2783         cache->origin_dev = ca->origin_dev;
2784         cache->cache_dev = ca->cache_dev;
2785
2786         ca->metadata_dev = ca->origin_dev = ca->cache_dev = NULL;
2787
2788         /* FIXME: factor out this whole section */
2789         origin_blocks = cache->origin_sectors = ca->origin_sectors;
2790         origin_blocks = block_div(origin_blocks, ca->block_size);
2791         cache->origin_blocks = to_oblock(origin_blocks);
2792
2793         cache->sectors_per_block = ca->block_size;
2794         if (dm_set_target_max_io_len(ti, cache->sectors_per_block)) {
2795                 r = -EINVAL;
2796                 goto bad;
2797         }
2798
2799         if (ca->block_size & (ca->block_size - 1)) {
2800                 dm_block_t cache_size = ca->cache_sectors;
2801
2802                 cache->sectors_per_block_shift = -1;
2803                 cache_size = block_div(cache_size, ca->block_size);
2804                 set_cache_size(cache, to_cblock(cache_size));
2805         } else {
2806                 cache->sectors_per_block_shift = __ffs(ca->block_size);
2807                 set_cache_size(cache, to_cblock(ca->cache_sectors >> cache->sectors_per_block_shift));
2808         }
2809
2810         r = create_cache_policy(cache, ca, error);
2811         if (r)
2812                 goto bad;
2813
2814         cache->policy_nr_args = ca->policy_argc;
2815         cache->migration_threshold = DEFAULT_MIGRATION_THRESHOLD;
2816
2817         r = set_config_values(cache, ca->policy_argc, ca->policy_argv);
2818         if (r) {
2819                 *error = "Error setting cache policy's config values";
2820                 goto bad;
2821         }
2822
2823         cmd = dm_cache_metadata_open(cache->metadata_dev->bdev,
2824                                      ca->block_size, may_format,
2825                                      dm_cache_policy_get_hint_size(cache->policy));
2826         if (IS_ERR(cmd)) {
2827                 *error = "Error creating metadata object";
2828                 r = PTR_ERR(cmd);
2829                 goto bad;
2830         }
2831         cache->cmd = cmd;
2832         set_cache_mode(cache, CM_WRITE);
2833         if (get_cache_mode(cache) != CM_WRITE) {
2834                 *error = "Unable to get write access to metadata, please check/repair metadata.";
2835                 r = -EINVAL;
2836                 goto bad;
2837         }
2838
2839         if (passthrough_mode(&cache->features)) {
2840                 bool all_clean;
2841
2842                 r = dm_cache_metadata_all_clean(cache->cmd, &all_clean);
2843                 if (r) {
2844                         *error = "dm_cache_metadata_all_clean() failed";
2845                         goto bad;
2846                 }
2847
2848                 if (!all_clean) {
2849                         *error = "Cannot enter passthrough mode unless all blocks are clean";
2850                         r = -EINVAL;
2851                         goto bad;
2852                 }
2853         }
2854
2855         spin_lock_init(&cache->lock);
2856         INIT_LIST_HEAD(&cache->deferred_cells);
2857         bio_list_init(&cache->deferred_bios);
2858         bio_list_init(&cache->deferred_flush_bios);
2859         bio_list_init(&cache->deferred_writethrough_bios);
2860         INIT_LIST_HEAD(&cache->quiesced_migrations);
2861         INIT_LIST_HEAD(&cache->completed_migrations);
2862         INIT_LIST_HEAD(&cache->need_commit_migrations);
2863         atomic_set(&cache->nr_allocated_migrations, 0);
2864         atomic_set(&cache->nr_io_migrations, 0);
2865         init_waitqueue_head(&cache->migration_wait);
2866
2867         init_waitqueue_head(&cache->quiescing_wait);
2868         atomic_set(&cache->quiescing, 0);
2869         atomic_set(&cache->quiescing_ack, 0);
2870
2871         r = -ENOMEM;
2872         atomic_set(&cache->nr_dirty, 0);
2873         cache->dirty_bitset = alloc_bitset(from_cblock(cache->cache_size));
2874         if (!cache->dirty_bitset) {
2875                 *error = "could not allocate dirty bitset";
2876                 goto bad;
2877         }
2878         clear_bitset(cache->dirty_bitset, from_cblock(cache->cache_size));
2879
2880         cache->discard_block_size =
2881                 calculate_discard_block_size(cache->sectors_per_block,
2882                                              cache->origin_sectors);
2883         cache->discard_nr_blocks = to_dblock(dm_sector_div_up(cache->origin_sectors,
2884                                                               cache->discard_block_size));
2885         cache->discard_bitset = alloc_bitset(from_dblock(cache->discard_nr_blocks));
2886         if (!cache->discard_bitset) {
2887                 *error = "could not allocate discard bitset";
2888                 goto bad;
2889         }
2890         clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks));
2891
2892         cache->copier = dm_kcopyd_client_create(&dm_kcopyd_throttle);
2893         if (IS_ERR(cache->copier)) {
2894                 *error = "could not create kcopyd client";
2895                 r = PTR_ERR(cache->copier);
2896                 goto bad;
2897         }
2898
2899         cache->wq = alloc_ordered_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM);
2900         if (!cache->wq) {
2901                 *error = "could not create workqueue for metadata object";
2902                 goto bad;
2903         }
2904         INIT_WORK(&cache->worker, do_worker);
2905         INIT_DELAYED_WORK(&cache->waker, do_waker);
2906         cache->last_commit_jiffies = jiffies;
2907
2908         cache->prison = dm_bio_prison_create();
2909         if (!cache->prison) {
2910                 *error = "could not create bio prison";
2911                 goto bad;
2912         }
2913
2914         cache->all_io_ds = dm_deferred_set_create();
2915         if (!cache->all_io_ds) {
2916                 *error = "could not create all_io deferred set";
2917                 goto bad;
2918         }
2919
2920         cache->migration_pool = mempool_create_slab_pool(MIGRATION_POOL_SIZE,
2921                                                          migration_cache);
2922         if (!cache->migration_pool) {
2923                 *error = "Error creating cache's migration mempool";
2924                 goto bad;
2925         }
2926
2927         cache->need_tick_bio = true;
2928         cache->sized = false;
2929         cache->invalidate = false;
2930         cache->commit_requested = false;
2931         cache->loaded_mappings = false;
2932         cache->loaded_discards = false;
2933
2934         load_stats(cache);
2935
2936         atomic_set(&cache->stats.demotion, 0);
2937         atomic_set(&cache->stats.promotion, 0);
2938         atomic_set(&cache->stats.copies_avoided, 0);
2939         atomic_set(&cache->stats.cache_cell_clash, 0);
2940         atomic_set(&cache->stats.commit_count, 0);
2941         atomic_set(&cache->stats.discard_count, 0);
2942
2943         spin_lock_init(&cache->invalidation_lock);
2944         INIT_LIST_HEAD(&cache->invalidation_requests);
2945
2946         iot_init(&cache->origin_tracker);
2947
2948         *result = cache;
2949         return 0;
2950
2951 bad:
2952         destroy(cache);
2953         return r;
2954 }
2955
2956 static int copy_ctr_args(struct cache *cache, int argc, const char **argv)
2957 {
2958         unsigned i;
2959         const char **copy;
2960
2961         copy = kcalloc(argc, sizeof(*copy), GFP_KERNEL);
2962         if (!copy)
2963                 return -ENOMEM;
2964         for (i = 0; i < argc; i++) {
2965                 copy[i] = kstrdup(argv[i], GFP_KERNEL);
2966                 if (!copy[i]) {
2967                         while (i--)
2968                                 kfree(copy[i]);
2969                         kfree(copy);
2970                         return -ENOMEM;
2971                 }
2972         }
2973
2974         cache->nr_ctr_args = argc;
2975         cache->ctr_args = copy;
2976
2977         return 0;
2978 }
2979
2980 static int cache_ctr(struct dm_target *ti, unsigned argc, char **argv)
2981 {
2982         int r = -EINVAL;
2983         struct cache_args *ca;
2984         struct cache *cache = NULL;
2985
2986         ca = kzalloc(sizeof(*ca), GFP_KERNEL);
2987         if (!ca) {
2988                 ti->error = "Error allocating memory for cache";
2989                 return -ENOMEM;
2990         }
2991         ca->ti = ti;
2992
2993         r = parse_cache_args(ca, argc, argv, &ti->error);
2994         if (r)
2995                 goto out;
2996
2997         r = cache_create(ca, &cache);
2998         if (r)
2999                 goto out;
3000
3001         r = copy_ctr_args(cache, argc - 3, (const char **)argv + 3);
3002         if (r) {
3003                 destroy(cache);
3004                 goto out;
3005         }
3006
3007         ti->private = cache;
3008
3009 out:
3010         destroy_cache_args(ca);
3011         return r;
3012 }
3013
3014 /*----------------------------------------------------------------*/
3015
3016 static int cache_map(struct dm_target *ti, struct bio *bio)
3017 {
3018         struct cache *cache = ti->private;
3019
3020         int r;
3021         struct dm_bio_prison_cell *cell = NULL;
3022         dm_oblock_t block = get_bio_block(cache, bio);
3023         size_t pb_data_size = get_per_bio_data_size(cache);
3024         bool can_migrate = false;
3025         bool fast_promotion;
3026         struct policy_result lookup_result;
3027         struct per_bio_data *pb = init_per_bio_data(bio, pb_data_size);
3028         struct old_oblock_lock ool;
3029
3030         ool.locker.fn = null_locker;
3031
3032         if (unlikely(from_oblock(block) >= from_oblock(cache->origin_blocks))) {
3033                 /*
3034                  * This can only occur if the io goes to a partial block at
3035                  * the end of the origin device.  We don't cache these.
3036                  * Just remap to the origin and carry on.
3037                  */
3038                 remap_to_origin(cache, bio);
3039                 accounted_begin(cache, bio);
3040                 return DM_MAPIO_REMAPPED;
3041         }
3042
3043         if (discard_or_flush(bio)) {
3044                 defer_bio(cache, bio);
3045                 return DM_MAPIO_SUBMITTED;
3046         }
3047
3048         /*
3049          * Check to see if that block is currently migrating.
3050          */
3051         cell = alloc_prison_cell(cache);
3052         if (!cell) {
3053                 defer_bio(cache, bio);
3054                 return DM_MAPIO_SUBMITTED;
3055         }
3056
3057         r = bio_detain(cache, block, bio, cell,
3058                        (cell_free_fn) free_prison_cell,
3059                        cache, &cell);
3060         if (r) {
3061                 if (r < 0)
3062                         defer_bio(cache, bio);
3063
3064                 return DM_MAPIO_SUBMITTED;
3065         }
3066
3067         fast_promotion = is_discarded_oblock(cache, block) || bio_writes_complete_block(cache, bio);
3068
3069         r = policy_map(cache->policy, block, false, can_migrate, fast_promotion,
3070                        bio, &ool.locker, &lookup_result);
3071         if (r == -EWOULDBLOCK) {
3072                 cell_defer(cache, cell, true);
3073                 return DM_MAPIO_SUBMITTED;
3074
3075         } else if (r) {
3076                 DMERR_LIMIT("%s: Unexpected return from cache replacement policy: %d",
3077                             cache_device_name(cache), r);
3078                 cell_defer(cache, cell, false);
3079                 bio_io_error(bio);
3080                 return DM_MAPIO_SUBMITTED;
3081         }
3082
3083         r = DM_MAPIO_REMAPPED;
3084         switch (lookup_result.op) {
3085         case POLICY_HIT:
3086                 if (passthrough_mode(&cache->features)) {
3087                         if (bio_data_dir(bio) == WRITE) {
3088                                 /*
3089                                  * We need to invalidate this block, so
3090                                  * defer for the worker thread.
3091                                  */
3092                                 cell_defer(cache, cell, true);
3093                                 r = DM_MAPIO_SUBMITTED;
3094
3095                         } else {
3096                                 inc_miss_counter(cache, bio);
3097                                 remap_to_origin_clear_discard(cache, bio, block);
3098                                 accounted_begin(cache, bio);
3099                                 inc_ds(cache, bio, cell);
3100                                 // FIXME: we want to remap hits or misses straight
3101                                 // away rather than passing over to the worker.
3102                                 cell_defer(cache, cell, false);
3103                         }
3104
3105                 } else {
3106                         inc_hit_counter(cache, bio);
3107                         if (bio_data_dir(bio) == WRITE && writethrough_mode(&cache->features) &&
3108                             !is_dirty(cache, lookup_result.cblock)) {
3109                                 remap_to_origin_then_cache(cache, bio, block, lookup_result.cblock);
3110                                 accounted_begin(cache, bio);
3111                                 inc_ds(cache, bio, cell);
3112                                 cell_defer(cache, cell, false);
3113
3114                         } else
3115                                 remap_cell_to_cache_dirty(cache, cell, block, lookup_result.cblock, false);
3116                 }
3117                 break;
3118
3119         case POLICY_MISS:
3120                 inc_miss_counter(cache, bio);
3121                 if (pb->req_nr != 0) {
3122                         /*
3123                          * This is a duplicate writethrough io that is no
3124                          * longer needed because the block has been demoted.
3125                          */
3126                         bio_endio(bio, 0);
3127                         // FIXME: remap everything as a miss
3128                         cell_defer(cache, cell, false);
3129                         r = DM_MAPIO_SUBMITTED;
3130
3131                 } else
3132                         remap_cell_to_origin_clear_discard(cache, cell, block, false);
3133                 break;
3134
3135         default:
3136                 DMERR_LIMIT("%s: %s: erroring bio: unknown policy op: %u",
3137                             cache_device_name(cache), __func__,
3138                             (unsigned) lookup_result.op);
3139                 cell_defer(cache, cell, false);
3140                 bio_io_error(bio);
3141                 r = DM_MAPIO_SUBMITTED;
3142         }
3143
3144         return r;
3145 }
3146
3147 static int cache_end_io(struct dm_target *ti, struct bio *bio, int error)
3148 {
3149         struct cache *cache = ti->private;
3150         unsigned long flags;
3151         size_t pb_data_size = get_per_bio_data_size(cache);
3152         struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
3153
3154         if (pb->tick) {
3155                 policy_tick(cache->policy, false);
3156
3157                 spin_lock_irqsave(&cache->lock, flags);
3158                 cache->need_tick_bio = true;
3159                 spin_unlock_irqrestore(&cache->lock, flags);
3160         }
3161
3162         check_for_quiesced_migrations(cache, pb);
3163         accounted_complete(cache, bio);
3164
3165         return 0;
3166 }
3167
3168 static int write_dirty_bitset(struct cache *cache)
3169 {
3170         unsigned i, r;
3171
3172         if (get_cache_mode(cache) >= CM_READ_ONLY)
3173                 return -EINVAL;
3174
3175         for (i = 0; i < from_cblock(cache->cache_size); i++) {
3176                 r = dm_cache_set_dirty(cache->cmd, to_cblock(i),
3177                                        is_dirty(cache, to_cblock(i)));
3178                 if (r) {
3179                         metadata_operation_failed(cache, "dm_cache_set_dirty", r);
3180                         return r;
3181                 }
3182         }
3183
3184         return 0;
3185 }
3186
3187 static int write_discard_bitset(struct cache *cache)
3188 {
3189         unsigned i, r;
3190
3191         if (get_cache_mode(cache) >= CM_READ_ONLY)
3192                 return -EINVAL;
3193
3194         r = dm_cache_discard_bitset_resize(cache->cmd, cache->discard_block_size,
3195                                            cache->discard_nr_blocks);
3196         if (r) {
3197                 DMERR("%s: could not resize on-disk discard bitset", cache_device_name(cache));
3198                 metadata_operation_failed(cache, "dm_cache_discard_bitset_resize", r);
3199                 return r;
3200         }
3201
3202         for (i = 0; i < from_dblock(cache->discard_nr_blocks); i++) {
3203                 r = dm_cache_set_discard(cache->cmd, to_dblock(i),
3204                                          is_discarded(cache, to_dblock(i)));
3205                 if (r) {
3206                         metadata_operation_failed(cache, "dm_cache_set_discard", r);
3207                         return r;
3208                 }
3209         }
3210
3211         return 0;
3212 }
3213
3214 static int write_hints(struct cache *cache)
3215 {
3216         int r;
3217
3218         if (get_cache_mode(cache) >= CM_READ_ONLY)
3219                 return -EINVAL;
3220
3221         r = dm_cache_write_hints(cache->cmd, cache->policy);
3222         if (r) {
3223                 metadata_operation_failed(cache, "dm_cache_write_hints", r);
3224                 return r;
3225         }
3226
3227         return 0;
3228 }
3229
3230 /*
3231  * returns true on success
3232  */
3233 static bool sync_metadata(struct cache *cache)
3234 {
3235         int r1, r2, r3, r4;
3236
3237         r1 = write_dirty_bitset(cache);
3238         if (r1)
3239                 DMERR("%s: could not write dirty bitset", cache_device_name(cache));
3240
3241         r2 = write_discard_bitset(cache);
3242         if (r2)
3243                 DMERR("%s: could not write discard bitset", cache_device_name(cache));
3244
3245         save_stats(cache);
3246
3247         r3 = write_hints(cache);
3248         if (r3)
3249                 DMERR("%s: could not write hints", cache_device_name(cache));
3250
3251         /*
3252          * If writing the above metadata failed, we still commit, but don't
3253          * set the clean shutdown flag.  This will effectively force every
3254          * dirty bit to be set on reload.
3255          */
3256         r4 = commit(cache, !r1 && !r2 && !r3);
3257         if (r4)
3258                 DMERR("%s: could not write cache metadata", cache_device_name(cache));
3259
3260         return !r1 && !r2 && !r3 && !r4;
3261 }
3262
3263 static void cache_postsuspend(struct dm_target *ti)
3264 {
3265         struct cache *cache = ti->private;
3266
3267         start_quiescing(cache);
3268         wait_for_migrations(cache);
3269         stop_worker(cache);
3270         requeue_deferred_bios(cache);
3271         requeue_deferred_cells(cache);
3272         stop_quiescing(cache);
3273
3274         if (get_cache_mode(cache) == CM_WRITE)
3275                 (void) sync_metadata(cache);
3276 }
3277
3278 static int load_mapping(void *context, dm_oblock_t oblock, dm_cblock_t cblock,
3279                         bool dirty, uint32_t hint, bool hint_valid)
3280 {
3281         int r;
3282         struct cache *cache = context;
3283
3284         r = policy_load_mapping(cache->policy, oblock, cblock, hint, hint_valid);
3285         if (r)
3286                 return r;
3287
3288         if (dirty)
3289                 set_dirty(cache, oblock, cblock);
3290         else
3291                 clear_dirty(cache, oblock, cblock);
3292
3293         return 0;
3294 }
3295
3296 /*
3297  * The discard block size in the on disk metadata is not
3298  * neccessarily the same as we're currently using.  So we have to
3299  * be careful to only set the discarded attribute if we know it
3300  * covers a complete block of the new size.
3301  */
3302 struct discard_load_info {
3303         struct cache *cache;
3304
3305         /*
3306          * These blocks are sized using the on disk dblock size, rather
3307          * than the current one.
3308          */
3309         dm_block_t block_size;
3310         dm_block_t discard_begin, discard_end;
3311 };
3312
3313 static void discard_load_info_init(struct cache *cache,
3314                                    struct discard_load_info *li)
3315 {
3316         li->cache = cache;
3317         li->discard_begin = li->discard_end = 0;
3318 }
3319
3320 static void set_discard_range(struct discard_load_info *li)
3321 {
3322         sector_t b, e;
3323
3324         if (li->discard_begin == li->discard_end)
3325                 return;
3326
3327         /*
3328          * Convert to sectors.
3329          */
3330         b = li->discard_begin * li->block_size;
3331         e = li->discard_end * li->block_size;
3332
3333         /*
3334          * Then convert back to the current dblock size.
3335          */
3336         b = dm_sector_div_up(b, li->cache->discard_block_size);
3337         sector_div(e, li->cache->discard_block_size);
3338
3339         /*
3340          * The origin may have shrunk, so we need to check we're still in
3341          * bounds.
3342          */
3343         if (e > from_dblock(li->cache->discard_nr_blocks))
3344                 e = from_dblock(li->cache->discard_nr_blocks);
3345
3346         for (; b < e; b++)
3347                 set_discard(li->cache, to_dblock(b));
3348 }
3349
3350 static int load_discard(void *context, sector_t discard_block_size,
3351                         dm_dblock_t dblock, bool discard)
3352 {
3353         struct discard_load_info *li = context;
3354
3355         li->block_size = discard_block_size;
3356
3357         if (discard) {
3358                 if (from_dblock(dblock) == li->discard_end)
3359                         /*
3360                          * We're already in a discard range, just extend it.
3361                          */
3362                         li->discard_end = li->discard_end + 1ULL;
3363
3364                 else {
3365                         /*
3366                          * Emit the old range and start a new one.
3367                          */
3368                         set_discard_range(li);
3369                         li->discard_begin = from_dblock(dblock);
3370                         li->discard_end = li->discard_begin + 1ULL;
3371                 }
3372         } else {
3373                 set_discard_range(li);
3374                 li->discard_begin = li->discard_end = 0;
3375         }
3376
3377         return 0;
3378 }
3379
3380 static dm_cblock_t get_cache_dev_size(struct cache *cache)
3381 {
3382         sector_t size = get_dev_size(cache->cache_dev);
3383         (void) sector_div(size, cache->sectors_per_block);
3384         return to_cblock(size);
3385 }
3386
3387 static bool can_resize(struct cache *cache, dm_cblock_t new_size)
3388 {
3389         if (from_cblock(new_size) > from_cblock(cache->cache_size))
3390                 return true;
3391
3392         /*
3393          * We can't drop a dirty block when shrinking the cache.
3394          */
3395         while (from_cblock(new_size) < from_cblock(cache->cache_size)) {
3396                 new_size = to_cblock(from_cblock(new_size) + 1);
3397                 if (is_dirty(cache, new_size)) {
3398                         DMERR("%s: unable to shrink cache; cache block %llu is dirty",
3399                               cache_device_name(cache),
3400                               (unsigned long long) from_cblock(new_size));
3401                         return false;
3402                 }
3403         }
3404
3405         return true;
3406 }
3407
3408 static int resize_cache_dev(struct cache *cache, dm_cblock_t new_size)
3409 {
3410         int r;
3411
3412         r = dm_cache_resize(cache->cmd, new_size);
3413         if (r) {
3414                 DMERR("%s: could not resize cache metadata", cache_device_name(cache));
3415                 metadata_operation_failed(cache, "dm_cache_resize", r);
3416                 return r;
3417         }
3418
3419         set_cache_size(cache, new_size);
3420
3421         return 0;
3422 }
3423
3424 static int cache_preresume(struct dm_target *ti)
3425 {
3426         int r = 0;
3427         struct cache *cache = ti->private;
3428         dm_cblock_t csize = get_cache_dev_size(cache);
3429
3430         /*
3431          * Check to see if the cache has resized.
3432          */
3433         if (!cache->sized) {
3434                 r = resize_cache_dev(cache, csize);
3435                 if (r)
3436                         return r;
3437
3438                 cache->sized = true;
3439
3440         } else if (csize != cache->cache_size) {
3441                 if (!can_resize(cache, csize))
3442                         return -EINVAL;
3443
3444                 r = resize_cache_dev(cache, csize);
3445                 if (r)
3446                         return r;
3447         }
3448
3449         if (!cache->loaded_mappings) {
3450                 r = dm_cache_load_mappings(cache->cmd, cache->policy,
3451                                            load_mapping, cache);
3452                 if (r) {
3453                         DMERR("%s: could not load cache mappings", cache_device_name(cache));
3454                         metadata_operation_failed(cache, "dm_cache_load_mappings", r);
3455                         return r;
3456                 }
3457
3458                 cache->loaded_mappings = true;
3459         }
3460
3461         if (!cache->loaded_discards) {
3462                 struct discard_load_info li;
3463
3464                 /*
3465                  * The discard bitset could have been resized, or the
3466                  * discard block size changed.  To be safe we start by
3467                  * setting every dblock to not discarded.
3468                  */
3469                 clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks));
3470
3471                 discard_load_info_init(cache, &li);
3472                 r = dm_cache_load_discards(cache->cmd, load_discard, &li);
3473                 if (r) {
3474                         DMERR("%s: could not load origin discards", cache_device_name(cache));
3475                         metadata_operation_failed(cache, "dm_cache_load_discards", r);
3476                         return r;
3477                 }
3478                 set_discard_range(&li);
3479
3480                 cache->loaded_discards = true;
3481         }
3482
3483         return r;
3484 }
3485
3486 static void cache_resume(struct dm_target *ti)
3487 {
3488         struct cache *cache = ti->private;
3489
3490         cache->need_tick_bio = true;
3491         do_waker(&cache->waker.work);
3492 }
3493
3494 /*
3495  * Status format:
3496  *
3497  * <metadata block size> <#used metadata blocks>/<#total metadata blocks>
3498  * <cache block size> <#used cache blocks>/<#total cache blocks>
3499  * <#read hits> <#read misses> <#write hits> <#write misses>
3500  * <#demotions> <#promotions> <#dirty>
3501  * <#features> <features>*
3502  * <#core args> <core args>
3503  * <policy name> <#policy args> <policy args>* <cache metadata mode> <needs_check>
3504  */
3505 static void cache_status(struct dm_target *ti, status_type_t type,
3506                          unsigned status_flags, char *result, unsigned maxlen)
3507 {
3508         int r = 0;
3509         unsigned i;
3510         ssize_t sz = 0;
3511         dm_block_t nr_free_blocks_metadata = 0;
3512         dm_block_t nr_blocks_metadata = 0;
3513         char buf[BDEVNAME_SIZE];
3514         struct cache *cache = ti->private;
3515         dm_cblock_t residency;
3516
3517         switch (type) {
3518         case STATUSTYPE_INFO:
3519                 if (get_cache_mode(cache) == CM_FAIL) {
3520                         DMEMIT("Fail");
3521                         break;
3522                 }
3523
3524                 /* Commit to ensure statistics aren't out-of-date */
3525                 if (!(status_flags & DM_STATUS_NOFLUSH_FLAG) && !dm_suspended(ti))
3526                         (void) commit(cache, false);
3527
3528                 r = dm_cache_get_free_metadata_block_count(cache->cmd, &nr_free_blocks_metadata);
3529                 if (r) {
3530                         DMERR("%s: dm_cache_get_free_metadata_block_count returned %d",
3531                               cache_device_name(cache), r);
3532                         goto err;
3533                 }
3534
3535                 r = dm_cache_get_metadata_dev_size(cache->cmd, &nr_blocks_metadata);
3536                 if (r) {
3537                         DMERR("%s: dm_cache_get_metadata_dev_size returned %d",
3538                               cache_device_name(cache), r);
3539                         goto err;
3540                 }
3541
3542                 residency = policy_residency(cache->policy);
3543
3544                 DMEMIT("%u %llu/%llu %u %llu/%llu %u %u %u %u %u %u %lu ",
3545                        (unsigned)DM_CACHE_METADATA_BLOCK_SIZE,
3546                        (unsigned long long)(nr_blocks_metadata - nr_free_blocks_metadata),
3547                        (unsigned long long)nr_blocks_metadata,
3548                        cache->sectors_per_block,
3549                        (unsigned long long) from_cblock(residency),
3550                        (unsigned long long) from_cblock(cache->cache_size),
3551                        (unsigned) atomic_read(&cache->stats.read_hit),
3552                        (unsigned) atomic_read(&cache->stats.read_miss),
3553                        (unsigned) atomic_read(&cache->stats.write_hit),
3554                        (unsigned) atomic_read(&cache->stats.write_miss),
3555                        (unsigned) atomic_read(&cache->stats.demotion),
3556                        (unsigned) atomic_read(&cache->stats.promotion),
3557                        (unsigned long) atomic_read(&cache->nr_dirty));
3558
3559                 if (writethrough_mode(&cache->features))
3560                         DMEMIT("1 writethrough ");
3561
3562                 else if (passthrough_mode(&cache->features))
3563                         DMEMIT("1 passthrough ");
3564
3565                 else if (writeback_mode(&cache->features))
3566                         DMEMIT("1 writeback ");
3567
3568                 else {
3569                         DMERR("%s: internal error: unknown io mode: %d",
3570                               cache_device_name(cache), (int) cache->features.io_mode);
3571                         goto err;
3572                 }
3573
3574                 DMEMIT("2 migration_threshold %llu ", (unsigned long long) cache->migration_threshold);
3575
3576                 DMEMIT("%s ", dm_cache_policy_get_name(cache->policy));
3577                 if (sz < maxlen) {
3578                         r = policy_emit_config_values(cache->policy, result, maxlen, &sz);
3579                         if (r)
3580                                 DMERR("%s: policy_emit_config_values returned %d",
3581                                       cache_device_name(cache), r);
3582                 }
3583
3584                 if (get_cache_mode(cache) == CM_READ_ONLY)
3585                         DMEMIT("ro ");
3586                 else
3587                         DMEMIT("rw ");
3588
3589                 if (dm_cache_metadata_needs_check(cache->cmd))
3590                         DMEMIT("needs_check ");
3591                 else
3592                         DMEMIT("- ");
3593
3594                 break;
3595
3596         case STATUSTYPE_TABLE:
3597                 format_dev_t(buf, cache->metadata_dev->bdev->bd_dev);
3598                 DMEMIT("%s ", buf);
3599                 format_dev_t(buf, cache->cache_dev->bdev->bd_dev);
3600                 DMEMIT("%s ", buf);
3601                 format_dev_t(buf, cache->origin_dev->bdev->bd_dev);
3602                 DMEMIT("%s", buf);
3603
3604                 for (i = 0; i < cache->nr_ctr_args - 1; i++)
3605                         DMEMIT(" %s", cache->ctr_args[i]);
3606                 if (cache->nr_ctr_args)
3607                         DMEMIT(" %s", cache->ctr_args[cache->nr_ctr_args - 1]);
3608         }
3609
3610         return;
3611
3612 err:
3613         DMEMIT("Error");
3614 }
3615
3616 /*
3617  * A cache block range can take two forms:
3618  *
3619  * i) A single cblock, eg. '3456'
3620  * ii) A begin and end cblock with dots between, eg. 123-234
3621  */
3622 static int parse_cblock_range(struct cache *cache, const char *str,
3623                               struct cblock_range *result)
3624 {
3625         char dummy;
3626         uint64_t b, e;
3627         int r;
3628
3629         /*
3630          * Try and parse form (ii) first.
3631          */
3632         r = sscanf(str, "%llu-%llu%c", &b, &e, &dummy);
3633         if (r < 0)
3634                 return r;
3635
3636         if (r == 2) {
3637                 result->begin = to_cblock(b);
3638                 result->end = to_cblock(e);
3639                 return 0;
3640         }
3641
3642         /*
3643          * That didn't work, try form (i).
3644          */
3645         r = sscanf(str, "%llu%c", &b, &dummy);
3646         if (r < 0)
3647                 return r;
3648
3649         if (r == 1) {
3650                 result->begin = to_cblock(b);
3651                 result->end = to_cblock(from_cblock(result->begin) + 1u);
3652                 return 0;
3653         }
3654
3655         DMERR("%s: invalid cblock range '%s'", cache_device_name(cache), str);
3656         return -EINVAL;
3657 }
3658
3659 static int validate_cblock_range(struct cache *cache, struct cblock_range *range)
3660 {
3661         uint64_t b = from_cblock(range->begin);
3662         uint64_t e = from_cblock(range->end);
3663         uint64_t n = from_cblock(cache->cache_size);
3664
3665         if (b >= n) {
3666                 DMERR("%s: begin cblock out of range: %llu >= %llu",
3667                       cache_device_name(cache), b, n);
3668                 return -EINVAL;
3669         }
3670
3671         if (e > n) {
3672                 DMERR("%s: end cblock out of range: %llu > %llu",
3673                       cache_device_name(cache), e, n);
3674                 return -EINVAL;
3675         }
3676
3677         if (b >= e) {
3678                 DMERR("%s: invalid cblock range: %llu >= %llu",
3679                       cache_device_name(cache), b, e);
3680                 return -EINVAL;
3681         }
3682
3683         return 0;
3684 }
3685
3686 static int request_invalidation(struct cache *cache, struct cblock_range *range)
3687 {
3688         struct invalidation_request req;
3689
3690         INIT_LIST_HEAD(&req.list);
3691         req.cblocks = range;
3692         atomic_set(&req.complete, 0);
3693         req.err = 0;
3694         init_waitqueue_head(&req.result_wait);
3695
3696         spin_lock(&cache->invalidation_lock);
3697         list_add(&req.list, &cache->invalidation_requests);
3698         spin_unlock(&cache->invalidation_lock);
3699         wake_worker(cache);
3700
3701         wait_event(req.result_wait, atomic_read(&req.complete));
3702         return req.err;
3703 }
3704
3705 static int process_invalidate_cblocks_message(struct cache *cache, unsigned count,
3706                                               const char **cblock_ranges)
3707 {
3708         int r = 0;
3709         unsigned i;
3710         struct cblock_range range;
3711
3712         if (!passthrough_mode(&cache->features)) {
3713                 DMERR("%s: cache has to be in passthrough mode for invalidation",
3714                       cache_device_name(cache));
3715                 return -EPERM;
3716         }
3717
3718         for (i = 0; i < count; i++) {
3719                 r = parse_cblock_range(cache, cblock_ranges[i], &range);
3720                 if (r)
3721                         break;
3722
3723                 r = validate_cblock_range(cache, &range);
3724                 if (r)
3725                         break;
3726
3727                 /*
3728                  * Pass begin and end origin blocks to the worker and wake it.
3729                  */
3730                 r = request_invalidation(cache, &range);
3731                 if (r)
3732                         break;
3733         }
3734
3735         return r;
3736 }
3737
3738 /*
3739  * Supports
3740  *      "<key> <value>"
3741  * and
3742  *     "invalidate_cblocks [(<begin>)|(<begin>-<end>)]*
3743  *
3744  * The key migration_threshold is supported by the cache target core.
3745  */
3746 static int cache_message(struct dm_target *ti, unsigned argc, char **argv)
3747 {
3748         struct cache *cache = ti->private;
3749
3750         if (!argc)
3751                 return -EINVAL;
3752
3753         if (get_cache_mode(cache) >= CM_READ_ONLY) {
3754                 DMERR("%s: unable to service cache target messages in READ_ONLY or FAIL mode",
3755                       cache_device_name(cache));
3756                 return -EOPNOTSUPP;
3757         }
3758
3759         if (!strcasecmp(argv[0], "invalidate_cblocks"))
3760                 return process_invalidate_cblocks_message(cache, argc - 1, (const char **) argv + 1);
3761
3762         if (argc != 2)
3763                 return -EINVAL;
3764
3765         return set_config_value(cache, argv[0], argv[1]);
3766 }
3767
3768 static int cache_iterate_devices(struct dm_target *ti,
3769                                  iterate_devices_callout_fn fn, void *data)
3770 {
3771         int r = 0;
3772         struct cache *cache = ti->private;
3773
3774         r = fn(ti, cache->cache_dev, 0, get_dev_size(cache->cache_dev), data);
3775         if (!r)
3776                 r = fn(ti, cache->origin_dev, 0, ti->len, data);
3777
3778         return r;
3779 }
3780
3781 /*
3782  * We assume I/O is going to the origin (which is the volume
3783  * more likely to have restrictions e.g. by being striped).
3784  * (Looking up the exact location of the data would be expensive
3785  * and could always be out of date by the time the bio is submitted.)
3786  */
3787 static int cache_bvec_merge(struct dm_target *ti,
3788                             struct bvec_merge_data *bvm,
3789                             struct bio_vec *biovec, int max_size)
3790 {
3791         struct cache *cache = ti->private;
3792         struct request_queue *q = bdev_get_queue(cache->origin_dev->bdev);
3793
3794         if (!q->merge_bvec_fn)
3795                 return max_size;
3796
3797         bvm->bi_bdev = cache->origin_dev->bdev;
3798         return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
3799 }
3800
3801 static void set_discard_limits(struct cache *cache, struct queue_limits *limits)
3802 {
3803         /*
3804          * FIXME: these limits may be incompatible with the cache device
3805          */
3806         limits->max_discard_sectors = min_t(sector_t, cache->discard_block_size * 1024,
3807                                             cache->origin_sectors);
3808         limits->discard_granularity = cache->discard_block_size << SECTOR_SHIFT;
3809 }
3810
3811 static void cache_io_hints(struct dm_target *ti, struct queue_limits *limits)
3812 {
3813         struct cache *cache = ti->private;
3814         uint64_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;
3815
3816         /*
3817          * If the system-determined stacked limits are compatible with the
3818          * cache's blocksize (io_opt is a factor) do not override them.
3819          */
3820         if (io_opt_sectors < cache->sectors_per_block ||
3821             do_div(io_opt_sectors, cache->sectors_per_block)) {
3822                 blk_limits_io_min(limits, cache->sectors_per_block << SECTOR_SHIFT);
3823                 blk_limits_io_opt(limits, cache->sectors_per_block << SECTOR_SHIFT);
3824         }
3825         set_discard_limits(cache, limits);
3826 }
3827
3828 /*----------------------------------------------------------------*/
3829
3830 static struct target_type cache_target = {
3831         .name = "cache",
3832         .version = {1, 8, 0},
3833         .module = THIS_MODULE,
3834         .ctr = cache_ctr,
3835         .dtr = cache_dtr,
3836         .map = cache_map,
3837         .end_io = cache_end_io,
3838         .postsuspend = cache_postsuspend,
3839         .preresume = cache_preresume,
3840         .resume = cache_resume,
3841         .status = cache_status,
3842         .message = cache_message,
3843         .iterate_devices = cache_iterate_devices,
3844         .merge = cache_bvec_merge,
3845         .io_hints = cache_io_hints,
3846 };
3847
3848 static int __init dm_cache_init(void)
3849 {
3850         int r;
3851
3852         r = dm_register_target(&cache_target);
3853         if (r) {
3854                 DMERR("cache target registration failed: %d", r);
3855                 return r;
3856         }
3857
3858         migration_cache = KMEM_CACHE(dm_cache_migration, 0);
3859         if (!migration_cache) {
3860                 dm_unregister_target(&cache_target);
3861                 return -ENOMEM;
3862         }
3863
3864         return 0;
3865 }
3866
3867 static void __exit dm_cache_exit(void)
3868 {
3869         dm_unregister_target(&cache_target);
3870         kmem_cache_destroy(migration_cache);
3871 }
3872
3873 module_init(dm_cache_init);
3874 module_exit(dm_cache_exit);
3875
3876 MODULE_DESCRIPTION(DM_NAME " cache target");
3877 MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
3878 MODULE_LICENSE("GPL");