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/init.h>
  15 #include <linux/mempool.h>
  16 #include <linux/module.h>
  17 #include <linux/slab.h>
  18 #include <linux/vmalloc.h>
  19
  20 #define DM_MSG_PREFIX "cache"
  21
  22 DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(cache_copy_throttle,
  23         "A percentage of time allocated for copying to and/or from cache");
  24
  25 /*----------------------------------------------------------------*/
  26
  27 /*
  28  * Glossary:
  29  *
  30  * oblock: index of an origin block
  31  * cblock: index of a cache block
  32  * promotion: movement of a block from origin to cache
  33  * demotion: movement of a block from cache to origin
  34  * migration: movement of a block between the origin and cache device,
  35  *            either direction
  36  */
  37
  38 /*----------------------------------------------------------------*/
  39
  40 static size_t bitset_size_in_bytes(unsigned nr_entries)
  41 {
  42         return sizeof(unsigned long) * dm_div_up(nr_entries, BITS_PER_LONG);
  43 }
  44
  45 static unsigned long *alloc_bitset(unsigned nr_entries)
  46 {
  47         size_t s = bitset_size_in_bytes(nr_entries);
  48         return vzalloc(s);
  49 }
  50
  51 static void clear_bitset(void *bitset, unsigned nr_entries)
  52 {
  53         size_t s = bitset_size_in_bytes(nr_entries);
  54         memset(bitset, 0, s);
  55 }
  56
  57 static void free_bitset(unsigned long *bits)
  58 {
  59         vfree(bits);
  60 }
  61
  62 /*----------------------------------------------------------------*/
  63
  64 /*
  65  * There are a couple of places where we let a bio run, but want to do some
  66  * work before calling its endio function.  We do this by temporarily
  67  * changing the endio fn.
  68  */
  69 struct dm_hook_info {
  70         bio_end_io_t *bi_end_io;
  71         void *bi_private;
  72 };
  73
  74 static void dm_hook_bio(struct dm_hook_info *h, struct bio *bio,
  75                         bio_end_io_t *bi_end_io, void *bi_private)
  76 {
  77         h->bi_end_io = bio->bi_end_io;
  78         h->bi_private = bio->bi_private;
  79
  80         bio->bi_end_io = bi_end_io;
  81         bio->bi_private = bi_private;
  82 }
  83
  84 static void dm_unhook_bio(struct dm_hook_info *h, struct bio *bio)
  85 {
  86         bio->bi_end_io = h->bi_end_io;
  87         bio->bi_private = h->bi_private;
  88
  89         /*
  90          * Must bump bi_remaining to allow bio to complete with
  91          * restored bi_end_io.
  92          */
  93         atomic_inc(&bio->bi_remaining);
  94 }
  95
  96 /*----------------------------------------------------------------*/
  97
  98 #define PRISON_CELLS 1024
  99 #define MIGRATION_POOL_SIZE 128
 100 #define COMMIT_PERIOD HZ
 101 #define MIGRATION_COUNT_WINDOW 10
 102
 103 /*
 104  * The block size of the device holding cache data must be
 105  * between 32KB and 1GB.
 106  */
 107 #define DATA_DEV_BLOCK_SIZE_MIN_SECTORS (32 * 1024 >> SECTOR_SHIFT)
 108 #define DATA_DEV_BLOCK_SIZE_MAX_SECTORS (1024 * 1024 * 1024 >> SECTOR_SHIFT)
 109
 110 /*
 111  * FIXME: the cache is read/write for the time being.
 112  */
 113 enum cache_metadata_mode {
 114         CM_WRITE,               /* metadata may be changed */
 115         CM_READ_ONLY,           /* metadata may not be changed */
 116 };
 117
 118 enum cache_io_mode {
 119         /*
 120          * Data is written to cached blocks only.  These blocks are marked
 121          * dirty.  If you lose the cache device you will lose data.
 122          * Potential performance increase for both reads and writes.
 123          */
 124         CM_IO_WRITEBACK,
 125
 126         /*
 127          * Data is written to both cache and origin.  Blocks are never
 128          * dirty.  Potential performance benfit for reads only.
 129          */
 130         CM_IO_WRITETHROUGH,
 131
 132         /*
 133          * A degraded mode useful for various cache coherency situations
 134          * (eg, rolling back snapshots).  Reads and writes always go to the
 135          * origin.  If a write goes to a cached oblock, then the cache
 136          * block is invalidated.
 137          */
 138         CM_IO_PASSTHROUGH
 139 };
 140
 141 struct cache_features {
 142         enum cache_metadata_mode mode;
 143         enum cache_io_mode io_mode;
 144 };
 145
 146 struct cache_stats {
 147         atomic_t read_hit;
 148         atomic_t read_miss;
 149         atomic_t write_hit;
 150         atomic_t write_miss;
 151         atomic_t demotion;
 152         atomic_t promotion;
 153         atomic_t copies_avoided;
 154         atomic_t cache_cell_clash;
 155         atomic_t commit_count;
 156         atomic_t discard_count;
 157 };
 158
 159 /*
 160  * Defines a range of cblocks, begin to (end - 1) are in the range.  end is
 161  * the one-past-the-end value.
 162  */
 163 struct cblock_range {
 164         dm_cblock_t begin;
 165         dm_cblock_t end;
 166 };
 167
 168 struct invalidation_request {
 169         struct list_head list;
 170         struct cblock_range *cblocks;
 171
 172         atomic_t complete;
 173         int err;
 174
 175         wait_queue_head_t result_wait;
 176 };
 177
 178 struct cache {
 179         struct dm_target *ti;
 180         struct dm_target_callbacks callbacks;
 181
 182         struct dm_cache_metadata *cmd;
 183
 184         /*
 185          * Metadata is written to this device.
 186          */
 187         struct dm_dev *metadata_dev;
 188
 189         /*
 190          * The slower of the two data devices.  Typically a spindle.
 191          */
 192         struct dm_dev *origin_dev;
 193
 194         /*
 195          * The faster of the two data devices.  Typically an SSD.
 196          */
 197         struct dm_dev *cache_dev;
 198
 199         /*
 200          * Size of the origin device in _complete_ blocks and native sectors.
 201          */
 202         dm_oblock_t origin_blocks;
 203         sector_t origin_sectors;
 204
 205         /*
 206          * Size of the cache device in blocks.
 207          */
 208         dm_cblock_t cache_size;
 209
 210         /*
 211          * Fields for converting from sectors to blocks.
 212          */
 213         uint32_t sectors_per_block;
 214         int sectors_per_block_shift;
 215
 216         spinlock_t lock;
 217         struct bio_list deferred_bios;
 218         struct bio_list deferred_flush_bios;
 219         struct bio_list deferred_writethrough_bios;
 220         struct list_head quiesced_migrations;
 221         struct list_head completed_migrations;
 222         struct list_head need_commit_migrations;
 223         sector_t migration_threshold;
 224         wait_queue_head_t migration_wait;
 225         atomic_t nr_migrations;
 226
 227         wait_queue_head_t quiescing_wait;
 228         atomic_t quiescing;
 229         atomic_t quiescing_ack;
 230
 231         /*
 232          * cache_size entries, dirty if set
 233          */
 234         dm_cblock_t nr_dirty;
 235         unsigned long *dirty_bitset;
 236
 237         /*
 238          * origin_blocks entries, discarded if set.
 239          */
 240         dm_oblock_t discard_nr_blocks;
 241         unsigned long *discard_bitset;
 242
 243         /*
 244          * Rather than reconstructing the table line for the status we just
 245          * save it and regurgitate.
 246          */
 247         unsigned nr_ctr_args;
 248         const char **ctr_args;
 249
 250         struct dm_kcopyd_client *copier;
 251         struct workqueue_struct *wq;
 252         struct work_struct worker;
 253
 254         struct delayed_work waker;
 255         unsigned long last_commit_jiffies;
 256
 257         struct dm_bio_prison *prison;
 258         struct dm_deferred_set *all_io_ds;
 259
 260         mempool_t *migration_pool;
 261         struct dm_cache_migration *next_migration;
 262
 263         struct dm_cache_policy *policy;
 264         unsigned policy_nr_args;
 265
 266         bool need_tick_bio:1;
 267         bool sized:1;
 268         bool invalidate:1;
 269         bool commit_requested:1;
 270         bool loaded_mappings:1;
 271         bool loaded_discards:1;
 272
 273         /*
 274          * Cache features such as write-through.
 275          */
 276         struct cache_features features;
 277
 278         struct cache_stats stats;
 279
 280         /*
 281          * Invalidation fields.
 282          */
 283         spinlock_t invalidation_lock;
 284         struct list_head invalidation_requests;
 285 };
 286
 287 struct per_bio_data {
 288         bool tick:1;
 289         unsigned req_nr:2;
 290         struct dm_deferred_entry *all_io_entry;
 291         struct dm_hook_info hook_info;
 292
 293         /*
 294          * writethrough fields.  These MUST remain at the end of this
 295          * structure and the 'cache' member must be the first as it
 296          * is used to determine the offset of the writethrough fields.
 297          */
 298         struct cache *cache;
 299         dm_cblock_t cblock;
 300         struct dm_bio_details bio_details;
 301 };
 302
 303 struct dm_cache_migration {
 304         struct list_head list;
 305         struct cache *cache;
 306
 307         unsigned long start_jiffies;
 308         dm_oblock_t old_oblock;
 309         dm_oblock_t new_oblock;
 310         dm_cblock_t cblock;
 311
 312         bool err:1;
 313         bool writeback:1;
 314         bool demote:1;
 315         bool promote:1;
 316         bool requeue_holder:1;
 317         bool invalidate:1;
 318
 319         struct dm_bio_prison_cell *old_ocell;
 320         struct dm_bio_prison_cell *new_ocell;
 321 };
 322
 323 /*
 324  * Processing a bio in the worker thread may require these memory
 325  * allocations.  We prealloc to avoid deadlocks (the same worker thread
 326  * frees them back to the mempool).
 327  */
 328 struct prealloc {
 329         struct dm_cache_migration *mg;
 330         struct dm_bio_prison_cell *cell1;
 331         struct dm_bio_prison_cell *cell2;
 332 };
 333
 334 static void wake_worker(struct cache *cache)
 335 {
 336         queue_work(cache->wq, &cache->worker);
 337 }
 338
 339 /*----------------------------------------------------------------*/
 340
 341 static struct dm_bio_prison_cell *alloc_prison_cell(struct cache *cache)
 342 {
 343         /* FIXME: change to use a local slab. */
 344         return dm_bio_prison_alloc_cell(cache->prison, GFP_NOWAIT);
 345 }
 346
 347 static void free_prison_cell(struct cache *cache, struct dm_bio_prison_cell *cell)
 348 {
 349         dm_bio_prison_free_cell(cache->prison, cell);
 350 }
 351
 352 static int prealloc_data_structs(struct cache *cache, struct prealloc *p)
 353 {
 354         if (!p->mg) {
 355                 p->mg = mempool_alloc(cache->migration_pool, GFP_NOWAIT);
 356                 if (!p->mg)
 357                         return -ENOMEM;
 358         }
 359
 360         if (!p->cell1) {
 361                 p->cell1 = alloc_prison_cell(cache);
 362                 if (!p->cell1)
 363                         return -ENOMEM;
 364         }
 365
 366         if (!p->cell2) {
 367                 p->cell2 = alloc_prison_cell(cache);
 368                 if (!p->cell2)
 369                         return -ENOMEM;
 370         }
 371
 372         return 0;
 373 }
 374
 375 static void prealloc_free_structs(struct cache *cache, struct prealloc *p)
 376 {
 377         if (p->cell2)
 378                 free_prison_cell(cache, p->cell2);
 379
 380         if (p->cell1)
 381                 free_prison_cell(cache, p->cell1);
 382
 383         if (p->mg)
 384                 mempool_free(p->mg, cache->migration_pool);
 385 }
 386
 387 static struct dm_cache_migration *prealloc_get_migration(struct prealloc *p)
 388 {
 389         struct dm_cache_migration *mg = p->mg;
 390
 391         BUG_ON(!mg);
 392         p->mg = NULL;
 393
 394         return mg;
 395 }
 396
 397 /*
 398  * You must have a cell within the prealloc struct to return.  If not this
 399  * function will BUG() rather than returning NULL.
 400  */
 401 static struct dm_bio_prison_cell *prealloc_get_cell(struct prealloc *p)
 402 {
 403         struct dm_bio_prison_cell *r = NULL;
 404
 405         if (p->cell1) {
 406                 r = p->cell1;
 407                 p->cell1 = NULL;
 408
 409         } else if (p->cell2) {
 410                 r = p->cell2;
 411                 p->cell2 = NULL;
 412         } else
 413                 BUG();
 414
 415         return r;
 416 }
 417
 418 /*
 419  * You can't have more than two cells in a prealloc struct.  BUG() will be
 420  * called if you try and overfill.
 421  */
 422 static void prealloc_put_cell(struct prealloc *p, struct dm_bio_prison_cell *cell)
 423 {
 424         if (!p->cell2)
 425                 p->cell2 = cell;
 426
 427         else if (!p->cell1)
 428                 p->cell1 = cell;
 429
 430         else
 431                 BUG();
 432 }
 433
 434 /*----------------------------------------------------------------*/
 435
 436 static void build_key(dm_oblock_t oblock, struct dm_cell_key *key)
 437 {
 438         key->virtual = 0;
 439         key->dev = 0;
 440         key->block = from_oblock(oblock);
 441 }
 442
 443 /*
 444  * The caller hands in a preallocated cell, and a free function for it.
 445  * The cell will be freed if there's an error, or if it wasn't used because
 446  * a cell with that key already exists.
 447  */
 448 typedef void (*cell_free_fn)(void *context, struct dm_bio_prison_cell *cell);
 449
 450 static int bio_detain(struct cache *cache, dm_oblock_t oblock,
 451                       struct bio *bio, struct dm_bio_prison_cell *cell_prealloc,
 452                       cell_free_fn free_fn, void *free_context,
 453                       struct dm_bio_prison_cell **cell_result)
 454 {
 455         int r;
 456         struct dm_cell_key key;
 457
 458         build_key(oblock, &key);
 459         r = dm_bio_detain(cache->prison, &key, bio, cell_prealloc, cell_result);
 460         if (r)
 461                 free_fn(free_context, cell_prealloc);
 462
 463         return r;
 464 }
 465
 466 static int get_cell(struct cache *cache,
 467                     dm_oblock_t oblock,
 468                     struct prealloc *structs,
 469                     struct dm_bio_prison_cell **cell_result)
 470 {
 471         int r;
 472         struct dm_cell_key key;
 473         struct dm_bio_prison_cell *cell_prealloc;
 474
 475         cell_prealloc = prealloc_get_cell(structs);
 476
 477         build_key(oblock, &key);
 478         r = dm_get_cell(cache->prison, &key, cell_prealloc, cell_result);
 479         if (r)
 480                 prealloc_put_cell(structs, cell_prealloc);
 481
 482         return r;
 483 }
 484
 485 /*----------------------------------------------------------------*/
 486
 487 static bool is_dirty(struct cache *cache, dm_cblock_t b)
 488 {
 489         return test_bit(from_cblock(b), cache->dirty_bitset);
 490 }
 491
 492 static void set_dirty(struct cache *cache, dm_oblock_t oblock, dm_cblock_t cblock)
 493 {
 494         if (!test_and_set_bit(from_cblock(cblock), cache->dirty_bitset)) {
 495                 cache->nr_dirty = to_cblock(from_cblock(cache->nr_dirty) + 1);
 496                 policy_set_dirty(cache->policy, oblock);
 497         }
 498 }
 499
 500 static void clear_dirty(struct cache *cache, dm_oblock_t oblock, dm_cblock_t cblock)
 501 {
 502         if (test_and_clear_bit(from_cblock(cblock), cache->dirty_bitset)) {
 503                 policy_clear_dirty(cache->policy, oblock);
 504                 cache->nr_dirty = to_cblock(from_cblock(cache->nr_dirty) - 1);
 505                 if (!from_cblock(cache->nr_dirty))
 506                         dm_table_event(cache->ti->table);
 507         }
 508 }
 509
 510 /*----------------------------------------------------------------*/
 511
 512 static bool block_size_is_power_of_two(struct cache *cache)
 513 {
 514         return cache->sectors_per_block_shift >= 0;
 515 }
 516
 517 /* gcc on ARM generates spurious references to __udivdi3 and __umoddi3 */
 518 #if defined(CONFIG_ARM) && __GNUC__ == 4 && __GNUC_MINOR__ <= 6
 519 __always_inline
 520 #endif
 521 static dm_block_t block_div(dm_block_t b, uint32_t n)
 522 {
 523         do_div(b, n);
 524
 525         return b;
 526 }
 527
 528 static void set_discard(struct cache *cache, dm_oblock_t b)
 529 {
 530         unsigned long flags;
 531
 532         atomic_inc(&cache->stats.discard_count);
 533
 534         spin_lock_irqsave(&cache->lock, flags);
 535         set_bit(from_oblock(b), cache->discard_bitset);
 536         spin_unlock_irqrestore(&cache->lock, flags);
 537 }
 538
 539 static void clear_discard(struct cache *cache, dm_oblock_t b)
 540 {
 541         unsigned long flags;
 542
 543         spin_lock_irqsave(&cache->lock, flags);
 544         clear_bit(from_oblock(b), cache->discard_bitset);
 545         spin_unlock_irqrestore(&cache->lock, flags);
 546 }
 547
 548 static bool is_discarded(struct cache *cache, dm_oblock_t b)
 549 {
 550         int r;
 551         unsigned long flags;
 552
 553         spin_lock_irqsave(&cache->lock, flags);
 554         r = test_bit(from_oblock(b), cache->discard_bitset);
 555         spin_unlock_irqrestore(&cache->lock, flags);
 556
 557         return r;
 558 }
 559
 560 static bool is_discarded_oblock(struct cache *cache, dm_oblock_t b)
 561 {
 562         int r;
 563         unsigned long flags;
 564
 565         spin_lock_irqsave(&cache->lock, flags);
 566         r = test_bit(from_oblock(b), cache->discard_bitset);
 567         spin_unlock_irqrestore(&cache->lock, flags);
 568
 569         return r;
 570 }
 571
 572 /*----------------------------------------------------------------*/
 573
 574 static void load_stats(struct cache *cache)
 575 {
 576         struct dm_cache_statistics stats;
 577
 578         dm_cache_metadata_get_stats(cache->cmd, &stats);
 579         atomic_set(&cache->stats.read_hit, stats.read_hits);
 580         atomic_set(&cache->stats.read_miss, stats.read_misses);
 581         atomic_set(&cache->stats.write_hit, stats.write_hits);
 582         atomic_set(&cache->stats.write_miss, stats.write_misses);
 583 }
 584
 585 static void save_stats(struct cache *cache)
 586 {
 587         struct dm_cache_statistics stats;
 588
 589         stats.read_hits = atomic_read(&cache->stats.read_hit);
 590         stats.read_misses = atomic_read(&cache->stats.read_miss);
 591         stats.write_hits = atomic_read(&cache->stats.write_hit);
 592         stats.write_misses = atomic_read(&cache->stats.write_miss);
 593
 594         dm_cache_metadata_set_stats(cache->cmd, &stats);
 595 }
 596
 597 /*----------------------------------------------------------------
 598  * Per bio data
 599  *--------------------------------------------------------------*/
 600
 601 /*
 602  * If using writeback, leave out struct per_bio_data's writethrough fields.
 603  */
 604 #define PB_DATA_SIZE_WB (offsetof(struct per_bio_data, cache))
 605 #define PB_DATA_SIZE_WT (sizeof(struct per_bio_data))
 606
 607 static bool writethrough_mode(struct cache_features *f)
 608 {
 609         return f->io_mode == CM_IO_WRITETHROUGH;
 610 }
 611
 612 static bool writeback_mode(struct cache_features *f)
 613 {
 614         return f->io_mode == CM_IO_WRITEBACK;
 615 }
 616
 617 static bool passthrough_mode(struct cache_features *f)
 618 {
 619         return f->io_mode == CM_IO_PASSTHROUGH;
 620 }
 621
 622 static size_t get_per_bio_data_size(struct cache *cache)
 623 {
 624         return writethrough_mode(&cache->features) ? PB_DATA_SIZE_WT : PB_DATA_SIZE_WB;
 625 }
 626
 627 static struct per_bio_data *get_per_bio_data(struct bio *bio, size_t data_size)
 628 {
 629         struct per_bio_data *pb = dm_per_bio_data(bio, data_size);
 630         BUG_ON(!pb);
 631         return pb;
 632 }
 633
 634 static struct per_bio_data *init_per_bio_data(struct bio *bio, size_t data_size)
 635 {
 636         struct per_bio_data *pb = get_per_bio_data(bio, data_size);
 637
 638         pb->tick = false;
 639         pb->req_nr = dm_bio_get_target_bio_nr(bio);
 640         pb->all_io_entry = NULL;
 641
 642         return pb;
 643 }
 644
 645 /*----------------------------------------------------------------
 646  * Remapping
 647  *--------------------------------------------------------------*/
 648 static void remap_to_origin(struct cache *cache, struct bio *bio)
 649 {
 650         bio->bi_bdev = cache->origin_dev->bdev;
 651 }
 652
 653 static void remap_to_cache(struct cache *cache, struct bio *bio,
 654                            dm_cblock_t cblock)
 655 {
 656         sector_t bi_sector = bio->bi_iter.bi_sector;
 657         sector_t block = from_cblock(cblock);
 658
 659         bio->bi_bdev = cache->cache_dev->bdev;
 660         if (!block_size_is_power_of_two(cache))
 661                 bio->bi_iter.bi_sector =
 662                         (block * cache->sectors_per_block) +
 663                         sector_div(bi_sector, cache->sectors_per_block);
 664         else
 665                 bio->bi_iter.bi_sector =
 666                         (block << cache->sectors_per_block_shift) |
 667                         (bi_sector & (cache->sectors_per_block - 1));
 668 }
 669
 670 static void check_if_tick_bio_needed(struct cache *cache, struct bio *bio)
 671 {
 672         unsigned long flags;
 673         size_t pb_data_size = get_per_bio_data_size(cache);
 674         struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
 675
 676         spin_lock_irqsave(&cache->lock, flags);
 677         if (cache->need_tick_bio &&
 678             !(bio->bi_rw & (REQ_FUA | REQ_FLUSH | REQ_DISCARD))) {
 679                 pb->tick = true;
 680                 cache->need_tick_bio = false;
 681         }
 682         spin_unlock_irqrestore(&cache->lock, flags);
 683 }
 684
 685 static void remap_to_origin_clear_discard(struct cache *cache, struct bio *bio,
 686                                   dm_oblock_t oblock)
 687 {
 688         check_if_tick_bio_needed(cache, bio);
 689         remap_to_origin(cache, bio);
 690         if (bio_data_dir(bio) == WRITE)
 691                 clear_discard(cache, oblock);
 692 }
 693
 694 static void remap_to_cache_dirty(struct cache *cache, struct bio *bio,
 695                                  dm_oblock_t oblock, dm_cblock_t cblock)
 696 {
 697         check_if_tick_bio_needed(cache, bio);
 698         remap_to_cache(cache, bio, cblock);
 699         if (bio_data_dir(bio) == WRITE) {
 700                 set_dirty(cache, oblock, cblock);
 701                 clear_discard(cache, oblock);
 702         }
 703 }
 704
 705 static dm_oblock_t get_bio_block(struct cache *cache, struct bio *bio)
 706 {
 707         sector_t block_nr = bio->bi_iter.bi_sector;
 708
 709         if (!block_size_is_power_of_two(cache))
 710                 (void) sector_div(block_nr, cache->sectors_per_block);
 711         else
 712                 block_nr >>= cache->sectors_per_block_shift;
 713
 714         return to_oblock(block_nr);
 715 }
 716
 717 static int bio_triggers_commit(struct cache *cache, struct bio *bio)
 718 {
 719         return bio->bi_rw & (REQ_FLUSH | REQ_FUA);
 720 }
 721
 722 static void issue(struct cache *cache, struct bio *bio)
 723 {
 724         unsigned long flags;
 725
 726         if (!bio_triggers_commit(cache, bio)) {
 727                 generic_make_request(bio);
 728                 return;
 729         }
 730
 731         /*
 732          * Batch together any bios that trigger commits and then issue a
 733          * single commit for them in do_worker().
 734          */
 735         spin_lock_irqsave(&cache->lock, flags);
 736         cache->commit_requested = true;
 737         bio_list_add(&cache->deferred_flush_bios, bio);
 738         spin_unlock_irqrestore(&cache->lock, flags);
 739 }
 740
 741 static void defer_writethrough_bio(struct cache *cache, struct bio *bio)
 742 {
 743         unsigned long flags;
 744
 745         spin_lock_irqsave(&cache->lock, flags);
 746         bio_list_add(&cache->deferred_writethrough_bios, bio);
 747         spin_unlock_irqrestore(&cache->lock, flags);
 748
 749         wake_worker(cache);
 750 }
 751
 752 static void writethrough_endio(struct bio *bio, int err)
 753 {
 754         struct per_bio_data *pb = get_per_bio_data(bio, PB_DATA_SIZE_WT);
 755
 756         dm_unhook_bio(&pb->hook_info, bio);
 757
 758         if (err) {
 759                 bio_endio(bio, err);
 760                 return;
 761         }
 762
 763         dm_bio_restore(&pb->bio_details, bio);
 764         remap_to_cache(pb->cache, bio, pb->cblock);
 765
 766         /*
 767          * We can't issue this bio directly, since we're in interrupt
 768          * context.  So it gets put on a bio list for processing by the
 769          * worker thread.
 770          */
 771         defer_writethrough_bio(pb->cache, bio);
 772 }
 773
 774 /*
 775  * When running in writethrough mode we need to send writes to clean blocks
 776  * to both the cache and origin devices.  In future we'd like to clone the
 777  * bio and send them in parallel, but for now we're doing them in
 778  * series as this is easier.
 779  */
 780 static void remap_to_origin_then_cache(struct cache *cache, struct bio *bio,
 781                                        dm_oblock_t oblock, dm_cblock_t cblock)
 782 {
 783         struct per_bio_data *pb = get_per_bio_data(bio, PB_DATA_SIZE_WT);
 784
 785         pb->cache = cache;
 786         pb->cblock = cblock;
 787         dm_hook_bio(&pb->hook_info, bio, writethrough_endio, NULL);
 788         dm_bio_record(&pb->bio_details, bio);
 789
 790         remap_to_origin_clear_discard(pb->cache, bio, oblock);
 791 }
 792
 793 /*----------------------------------------------------------------
 794  * Migration processing
 795  *
 796  * Migration covers moving data from the origin device to the cache, or
 797  * vice versa.
 798  *--------------------------------------------------------------*/
 799 static void free_migration(struct dm_cache_migration *mg)
 800 {
 801         mempool_free(mg, mg->cache->migration_pool);
 802 }
 803
 804 static void inc_nr_migrations(struct cache *cache)
 805 {
 806         atomic_inc(&cache->nr_migrations);
 807 }
 808
 809 static void dec_nr_migrations(struct cache *cache)
 810 {
 811         atomic_dec(&cache->nr_migrations);
 812
 813         /*
 814          * Wake the worker in case we're suspending the target.
 815          */
 816         wake_up(&cache->migration_wait);
 817 }
 818
 819 static void __cell_defer(struct cache *cache, struct dm_bio_prison_cell *cell,
 820                          bool holder)
 821 {
 822         (holder ? dm_cell_release : dm_cell_release_no_holder)
 823                 (cache->prison, cell, &cache->deferred_bios);
 824         free_prison_cell(cache, cell);
 825 }
 826
 827 static void cell_defer(struct cache *cache, struct dm_bio_prison_cell *cell,
 828                        bool holder)
 829 {
 830         unsigned long flags;
 831
 832         spin_lock_irqsave(&cache->lock, flags);
 833         __cell_defer(cache, cell, holder);
 834         spin_unlock_irqrestore(&cache->lock, flags);
 835
 836         wake_worker(cache);
 837 }
 838
 839 static void cleanup_migration(struct dm_cache_migration *mg)
 840 {
 841         struct cache *cache = mg->cache;
 842         free_migration(mg);
 843         dec_nr_migrations(cache);
 844 }
 845
 846 static void migration_failure(struct dm_cache_migration *mg)
 847 {
 848         struct cache *cache = mg->cache;
 849
 850         if (mg->writeback) {
 851                 DMWARN_LIMIT("writeback failed; couldn't copy block");
 852                 set_dirty(cache, mg->old_oblock, mg->cblock);
 853                 cell_defer(cache, mg->old_ocell, false);
 854
 855         } else if (mg->demote) {
 856                 DMWARN_LIMIT("demotion failed; couldn't copy block");
 857                 policy_force_mapping(cache->policy, mg->new_oblock, mg->old_oblock);
 858
 859                 cell_defer(cache, mg->old_ocell, mg->promote ? false : true);
 860                 if (mg->promote)
 861                         cell_defer(cache, mg->new_ocell, true);
 862         } else {
 863                 DMWARN_LIMIT("promotion failed; couldn't copy block");
 864                 policy_remove_mapping(cache->policy, mg->new_oblock);
 865                 cell_defer(cache, mg->new_ocell, true);
 866         }
 867
 868         cleanup_migration(mg);
 869 }
 870
 871 static void migration_success_pre_commit(struct dm_cache_migration *mg)
 872 {
 873         unsigned long flags;
 874         struct cache *cache = mg->cache;
 875
 876         if (mg->writeback) {
 877                 cell_defer(cache, mg->old_ocell, false);
 878                 clear_dirty(cache, mg->old_oblock, mg->cblock);
 879                 cleanup_migration(mg);
 880                 return;
 881
 882         } else if (mg->demote) {
 883                 if (dm_cache_remove_mapping(cache->cmd, mg->cblock)) {
 884                         DMWARN_LIMIT("demotion failed; couldn't update on disk metadata");
 885                         policy_force_mapping(cache->policy, mg->new_oblock,
 886                                              mg->old_oblock);
 887                         if (mg->promote)
 888                                 cell_defer(cache, mg->new_ocell, true);
 889                         cleanup_migration(mg);
 890                         return;
 891                 }
 892         } else {
 893                 if (dm_cache_insert_mapping(cache->cmd, mg->cblock, mg->new_oblock)) {
 894                         DMWARN_LIMIT("promotion failed; couldn't update on disk metadata");
 895                         policy_remove_mapping(cache->policy, mg->new_oblock);
 896                         cleanup_migration(mg);
 897                         return;
 898                 }
 899         }
 900
 901         spin_lock_irqsave(&cache->lock, flags);
 902         list_add_tail(&mg->list, &cache->need_commit_migrations);
 903         cache->commit_requested = true;
 904         spin_unlock_irqrestore(&cache->lock, flags);
 905 }
 906
 907 static void migration_success_post_commit(struct dm_cache_migration *mg)
 908 {
 909         unsigned long flags;
 910         struct cache *cache = mg->cache;
 911
 912         if (mg->writeback) {
 913                 DMWARN("writeback unexpectedly triggered commit");
 914                 return;
 915
 916         } else if (mg->demote) {
 917                 cell_defer(cache, mg->old_ocell, mg->promote ? false : true);
 918
 919                 if (mg->promote) {
 920                         mg->demote = false;
 921
 922                         spin_lock_irqsave(&cache->lock, flags);
 923                         list_add_tail(&mg->list, &cache->quiesced_migrations);
 924                         spin_unlock_irqrestore(&cache->lock, flags);
 925
 926                 } else {
 927                         if (mg->invalidate)
 928                                 policy_remove_mapping(cache->policy, mg->old_oblock);
 929                         cleanup_migration(mg);
 930                 }
 931
 932         } else {
 933                 if (mg->requeue_holder)
 934                         cell_defer(cache, mg->new_ocell, true);
 935                 else {
 936                         bio_endio(mg->new_ocell->holder, 0);
 937                         cell_defer(cache, mg->new_ocell, false);
 938                 }
 939                 clear_dirty(cache, mg->new_oblock, mg->cblock);
 940                 cleanup_migration(mg);
 941         }
 942 }
 943
 944 static void copy_complete(int read_err, unsigned long write_err, void *context)
 945 {
 946         unsigned long flags;
 947         struct dm_cache_migration *mg = (struct dm_cache_migration *) context;
 948         struct cache *cache = mg->cache;
 949
 950         if (read_err || write_err)
 951                 mg->err = true;
 952
 953         spin_lock_irqsave(&cache->lock, flags);
 954         list_add_tail(&mg->list, &cache->completed_migrations);
 955         spin_unlock_irqrestore(&cache->lock, flags);
 956
 957         wake_worker(cache);
 958 }
 959
 960 static void issue_copy_real(struct dm_cache_migration *mg)
 961 {
 962         int r;
 963         struct dm_io_region o_region, c_region;
 964         struct cache *cache = mg->cache;
 965         sector_t cblock = from_cblock(mg->cblock);
 966
 967         o_region.bdev = cache->origin_dev->bdev;
 968         o_region.count = cache->sectors_per_block;
 969
 970         c_region.bdev = cache->cache_dev->bdev;
 971         c_region.sector = cblock * cache->sectors_per_block;
 972         c_region.count = cache->sectors_per_block;
 973
 974         if (mg->writeback || mg->demote) {
 975                 /* demote */
 976                 o_region.sector = from_oblock(mg->old_oblock) * cache->sectors_per_block;
 977                 r = dm_kcopyd_copy(cache->copier, &c_region, 1, &o_region, 0, copy_complete, mg);
 978         } else {
 979                 /* promote */
 980                 o_region.sector = from_oblock(mg->new_oblock) * cache->sectors_per_block;
 981                 r = dm_kcopyd_copy(cache->copier, &o_region, 1, &c_region, 0, copy_complete, mg);
 982         }
 983
 984         if (r < 0) {
 985                 DMERR_LIMIT("issuing migration failed");
 986                 migration_failure(mg);
 987         }
 988 }
 989
 990 static void overwrite_endio(struct bio *bio, int err)
 991 {
 992         struct dm_cache_migration *mg = bio->bi_private;
 993         struct cache *cache = mg->cache;
 994         size_t pb_data_size = get_per_bio_data_size(cache);
 995         struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
 996         unsigned long flags;
 997
 998         dm_unhook_bio(&pb->hook_info, bio);
 999
1000         if (err)
1001                 mg->err = true;
1002
1003         mg->requeue_holder = false;
1004
1005         spin_lock_irqsave(&cache->lock, flags);
1006         list_add_tail(&mg->list, &cache->completed_migrations);
1007         spin_unlock_irqrestore(&cache->lock, flags);
1008
1009         wake_worker(cache);
1010 }
1011
1012 static void issue_overwrite(struct dm_cache_migration *mg, struct bio *bio)
1013 {
1014         size_t pb_data_size = get_per_bio_data_size(mg->cache);
1015         struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
1016
1017         dm_hook_bio(&pb->hook_info, bio, overwrite_endio, mg);
1018         remap_to_cache_dirty(mg->cache, bio, mg->new_oblock, mg->cblock);
1019         generic_make_request(bio);
1020 }
1021
1022 static bool bio_writes_complete_block(struct cache *cache, struct bio *bio)
1023 {
1024         return (bio_data_dir(bio) == WRITE) &&
1025                 (bio->bi_iter.bi_size == (cache->sectors_per_block << SECTOR_SHIFT));
1026 }
1027
1028 static void avoid_copy(struct dm_cache_migration *mg)
1029 {
1030         atomic_inc(&mg->cache->stats.copies_avoided);
1031         migration_success_pre_commit(mg);
1032 }
1033
1034 static void issue_copy(struct dm_cache_migration *mg)
1035 {
1036         bool avoid;
1037         struct cache *cache = mg->cache;
1038
1039         if (mg->writeback || mg->demote)
1040                 avoid = !is_dirty(cache, mg->cblock) ||
1041                         is_discarded_oblock(cache, mg->old_oblock);
1042         else {
1043                 struct bio *bio = mg->new_ocell->holder;
1044
1045                 avoid = is_discarded_oblock(cache, mg->new_oblock);
1046
1047                 if (!avoid && bio_writes_complete_block(cache, bio)) {
1048                         issue_overwrite(mg, bio);
1049                         return;
1050                 }
1051         }
1052
1053         avoid ? avoid_copy(mg) : issue_copy_real(mg);
1054 }
1055
1056 static void complete_migration(struct dm_cache_migration *mg)
1057 {
1058         if (mg->err)
1059                 migration_failure(mg);
1060         else
1061                 migration_success_pre_commit(mg);
1062 }
1063
1064 static void process_migrations(struct cache *cache, struct list_head *head,
1065                                void (*fn)(struct dm_cache_migration *))
1066 {
1067         unsigned long flags;
1068         struct list_head list;
1069         struct dm_cache_migration *mg, *tmp;
1070
1071         INIT_LIST_HEAD(&list);
1072         spin_lock_irqsave(&cache->lock, flags);
1073         list_splice_init(head, &list);
1074         spin_unlock_irqrestore(&cache->lock, flags);
1075
1076         list_for_each_entry_safe(mg, tmp, &list, list)
1077                 fn(mg);
1078 }
1079
1080 static void __queue_quiesced_migration(struct dm_cache_migration *mg)
1081 {
1082         list_add_tail(&mg->list, &mg->cache->quiesced_migrations);
1083 }
1084
1085 static void queue_quiesced_migration(struct dm_cache_migration *mg)
1086 {
1087         unsigned long flags;
1088         struct cache *cache = mg->cache;
1089
1090         spin_lock_irqsave(&cache->lock, flags);
1091         __queue_quiesced_migration(mg);
1092         spin_unlock_irqrestore(&cache->lock, flags);
1093
1094         wake_worker(cache);
1095 }
1096
1097 static void queue_quiesced_migrations(struct cache *cache, struct list_head *work)
1098 {
1099         unsigned long flags;
1100         struct dm_cache_migration *mg, *tmp;
1101
1102         spin_lock_irqsave(&cache->lock, flags);
1103         list_for_each_entry_safe(mg, tmp, work, list)
1104                 __queue_quiesced_migration(mg);
1105         spin_unlock_irqrestore(&cache->lock, flags);
1106
1107         wake_worker(cache);
1108 }
1109
1110 static void check_for_quiesced_migrations(struct cache *cache,
1111                                           struct per_bio_data *pb)
1112 {
1113         struct list_head work;
1114
1115         if (!pb->all_io_entry)
1116                 return;
1117
1118         INIT_LIST_HEAD(&work);
1119         if (pb->all_io_entry)
1120                 dm_deferred_entry_dec(pb->all_io_entry, &work);
1121
1122         if (!list_empty(&work))
1123                 queue_quiesced_migrations(cache, &work);
1124 }
1125
1126 static void quiesce_migration(struct dm_cache_migration *mg)
1127 {
1128         if (!dm_deferred_set_add_work(mg->cache->all_io_ds, &mg->list))
1129                 queue_quiesced_migration(mg);
1130 }
1131
1132 static void promote(struct cache *cache, struct prealloc *structs,
1133                     dm_oblock_t oblock, dm_cblock_t cblock,
1134                     struct dm_bio_prison_cell *cell)
1135 {
1136         struct dm_cache_migration *mg = prealloc_get_migration(structs);
1137
1138         mg->err = false;
1139         mg->writeback = false;
1140         mg->demote = false;
1141         mg->promote = true;
1142         mg->requeue_holder = true;
1143         mg->invalidate = false;
1144         mg->cache = cache;
1145         mg->new_oblock = oblock;
1146         mg->cblock = cblock;
1147         mg->old_ocell = NULL;
1148         mg->new_ocell = cell;
1149         mg->start_jiffies = jiffies;
1150
1151         inc_nr_migrations(cache);
1152         quiesce_migration(mg);
1153 }
1154
1155 static void writeback(struct cache *cache, struct prealloc *structs,
1156                       dm_oblock_t oblock, dm_cblock_t cblock,
1157                       struct dm_bio_prison_cell *cell)
1158 {
1159         struct dm_cache_migration *mg = prealloc_get_migration(structs);
1160
1161         mg->err = false;
1162         mg->writeback = true;
1163         mg->demote = false;
1164         mg->promote = false;
1165         mg->requeue_holder = true;
1166         mg->invalidate = false;
1167         mg->cache = cache;
1168         mg->old_oblock = oblock;
1169         mg->cblock = cblock;
1170         mg->old_ocell = cell;
1171         mg->new_ocell = NULL;
1172         mg->start_jiffies = jiffies;
1173
1174         inc_nr_migrations(cache);
1175         quiesce_migration(mg);
1176 }
1177
1178 static void demote_then_promote(struct cache *cache, struct prealloc *structs,
1179                                 dm_oblock_t old_oblock, dm_oblock_t new_oblock,
1180                                 dm_cblock_t cblock,
1181                                 struct dm_bio_prison_cell *old_ocell,
1182                                 struct dm_bio_prison_cell *new_ocell)
1183 {
1184         struct dm_cache_migration *mg = prealloc_get_migration(structs);
1185
1186         mg->err = false;
1187         mg->writeback = false;
1188         mg->demote = true;
1189         mg->promote = true;
1190         mg->requeue_holder = true;
1191         mg->invalidate = false;
1192         mg->cache = cache;
1193         mg->old_oblock = old_oblock;
1194         mg->new_oblock = new_oblock;
1195         mg->cblock = cblock;
1196         mg->old_ocell = old_ocell;
1197         mg->new_ocell = new_ocell;
1198         mg->start_jiffies = jiffies;
1199
1200         inc_nr_migrations(cache);
1201         quiesce_migration(mg);
1202 }
1203
1204 /*
1205  * Invalidate a cache entry.  No writeback occurs; any changes in the cache
1206  * block are thrown away.
1207  */
1208 static void invalidate(struct cache *cache, struct prealloc *structs,
1209                        dm_oblock_t oblock, dm_cblock_t cblock,
1210                        struct dm_bio_prison_cell *cell)
1211 {
1212         struct dm_cache_migration *mg = prealloc_get_migration(structs);
1213
1214         mg->err = false;
1215         mg->writeback = false;
1216         mg->demote = true;
1217         mg->promote = false;
1218         mg->requeue_holder = true;
1219         mg->invalidate = true;
1220         mg->cache = cache;
1221         mg->old_oblock = oblock;
1222         mg->cblock = cblock;
1223         mg->old_ocell = cell;
1224         mg->new_ocell = NULL;
1225         mg->start_jiffies = jiffies;
1226
1227         inc_nr_migrations(cache);
1228         quiesce_migration(mg);
1229 }
1230
1231 /*----------------------------------------------------------------
1232  * bio processing
1233  *--------------------------------------------------------------*/
1234 static void defer_bio(struct cache *cache, struct bio *bio)
1235 {
1236         unsigned long flags;
1237
1238         spin_lock_irqsave(&cache->lock, flags);
1239         bio_list_add(&cache->deferred_bios, bio);
1240         spin_unlock_irqrestore(&cache->lock, flags);
1241
1242         wake_worker(cache);
1243 }
1244
1245 static void process_flush_bio(struct cache *cache, struct bio *bio)
1246 {
1247         size_t pb_data_size = get_per_bio_data_size(cache);
1248         struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
1249
1250         BUG_ON(bio->bi_iter.bi_size);
1251         if (!pb->req_nr)
1252                 remap_to_origin(cache, bio);
1253         else
1254                 remap_to_cache(cache, bio, 0);
1255
1256         issue(cache, bio);
1257 }
1258
1259 /*
1260  * People generally discard large parts of a device, eg, the whole device
1261  * when formatting.  Splitting these large discards up into cache block
1262  * sized ios and then quiescing (always neccessary for discard) takes too
1263  * long.
1264  *
1265  * We keep it simple, and allow any size of discard to come in, and just
1266  * mark off blocks on the discard bitset.  No passdown occurs!
1267  *
1268  * To implement passdown we need to change the bio_prison such that a cell
1269  * can have a key that spans many blocks.
1270  */
1271 static void process_discard_bio(struct cache *cache, struct bio *bio)
1272 {
1273         dm_block_t start_block = dm_sector_div_up(bio->bi_iter.bi_sector,
1274                                                   cache->sectors_per_block);
1275         dm_block_t end_block = bio_end_sector(bio);
1276         dm_block_t b;
1277
1278         end_block = block_div(end_block, cache->sectors_per_block);
1279
1280         for (b = start_block; b < end_block; b++)
1281                 set_discard(cache, to_oblock(b));
1282
1283         bio_endio(bio, 0);
1284 }
1285
1286 static bool spare_migration_bandwidth(struct cache *cache)
1287 {
1288         sector_t current_volume = (atomic_read(&cache->nr_migrations) + 1) *
1289                 cache->sectors_per_block;
1290         return current_volume < cache->migration_threshold;
1291 }
1292
1293 static void inc_hit_counter(struct cache *cache, struct bio *bio)
1294 {
1295         atomic_inc(bio_data_dir(bio) == READ ?
1296                    &cache->stats.read_hit : &cache->stats.write_hit);
1297 }
1298
1299 static void inc_miss_counter(struct cache *cache, struct bio *bio)
1300 {
1301         atomic_inc(bio_data_dir(bio) == READ ?
1302                    &cache->stats.read_miss : &cache->stats.write_miss);
1303 }
1304
1305 static void issue_cache_bio(struct cache *cache, struct bio *bio,
1306                             struct per_bio_data *pb,
1307                             dm_oblock_t oblock, dm_cblock_t cblock)
1308 {
1309         pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
1310         remap_to_cache_dirty(cache, bio, oblock, cblock);
1311         issue(cache, bio);
1312 }
1313
1314 static void process_bio(struct cache *cache, struct prealloc *structs,
1315                         struct bio *bio)
1316 {
1317         int r;
1318         bool release_cell = true;
1319         dm_oblock_t block = get_bio_block(cache, bio);
1320         struct dm_bio_prison_cell *cell_prealloc, *old_ocell, *new_ocell;
1321         struct policy_result lookup_result;
1322         size_t pb_data_size = get_per_bio_data_size(cache);
1323         struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
1324         bool discarded_block = is_discarded_oblock(cache, block);
1325         bool passthrough = passthrough_mode(&cache->features);
1326         bool can_migrate = !passthrough && (discarded_block || spare_migration_bandwidth(cache));
1327
1328         /*
1329          * Check to see if that block is currently migrating.
1330          */
1331         cell_prealloc = prealloc_get_cell(structs);
1332         r = bio_detain(cache, block, bio, cell_prealloc,
1333                        (cell_free_fn) prealloc_put_cell,
1334                        structs, &new_ocell);
1335         if (r > 0)
1336                 return;
1337
1338         r = policy_map(cache->policy, block, true, can_migrate, discarded_block,
1339                        bio, &lookup_result);
1340
1341         if (r == -EWOULDBLOCK)
1342                 /* migration has been denied */
1343                 lookup_result.op = POLICY_MISS;
1344
1345         switch (lookup_result.op) {
1346         case POLICY_HIT:
1347                 if (passthrough) {
1348                         inc_miss_counter(cache, bio);
1349
1350                         /*
1351                          * Passthrough always maps to the origin,
1352                          * invalidating any cache blocks that are written
1353                          * to.
1354                          */
1355
1356                         if (bio_data_dir(bio) == WRITE) {
1357                                 atomic_inc(&cache->stats.demotion);
1358                                 invalidate(cache, structs, block, lookup_result.cblock, new_ocell);
1359                                 release_cell = false;
1360
1361                         } else {
1362                                 /* FIXME: factor out issue_origin() */
1363                                 pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
1364                                 remap_to_origin_clear_discard(cache, bio, block);
1365                                 issue(cache, bio);
1366                         }
1367                 } else {
1368                         inc_hit_counter(cache, bio);
1369
1370                         if (bio_data_dir(bio) == WRITE &&
1371                             writethrough_mode(&cache->features) &&
1372                             !is_dirty(cache, lookup_result.cblock)) {
1373                                 pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
1374                                 remap_to_origin_then_cache(cache, bio, block, lookup_result.cblock);
1375                                 issue(cache, bio);
1376                         } else
1377                                 issue_cache_bio(cache, bio, pb, block, lookup_result.cblock);
1378                 }
1379
1380                 break;
1381
1382         case POLICY_MISS:
1383                 inc_miss_counter(cache, bio);
1384                 pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
1385                 remap_to_origin_clear_discard(cache, bio, block);
1386                 issue(cache, bio);
1387                 break;
1388
1389         case POLICY_NEW:
1390                 atomic_inc(&cache->stats.promotion);
1391                 promote(cache, structs, block, lookup_result.cblock, new_ocell);
1392                 release_cell = false;
1393                 break;
1394
1395         case POLICY_REPLACE:
1396                 cell_prealloc = prealloc_get_cell(structs);
1397                 r = bio_detain(cache, lookup_result.old_oblock, bio, cell_prealloc,
1398                                (cell_free_fn) prealloc_put_cell,
1399                                structs, &old_ocell);
1400                 if (r > 0) {
1401                         /*
1402                          * We have to be careful to avoid lock inversion of
1403                          * the cells.  So we back off, and wait for the
1404                          * old_ocell to become free.
1405                          */
1406                         policy_force_mapping(cache->policy, block,
1407                                              lookup_result.old_oblock);
1408                         atomic_inc(&cache->stats.cache_cell_clash);
1409                         break;
1410                 }
1411                 atomic_inc(&cache->stats.demotion);
1412                 atomic_inc(&cache->stats.promotion);
1413
1414                 demote_then_promote(cache, structs, lookup_result.old_oblock,
1415                                     block, lookup_result.cblock,
1416                                     old_ocell, new_ocell);
1417                 release_cell = false;
1418                 break;
1419
1420         default:
1421                 DMERR_LIMIT("%s: erroring bio, unknown policy op: %u", __func__,
1422                             (unsigned) lookup_result.op);
1423                 bio_io_error(bio);
1424         }
1425
1426         if (release_cell)
1427                 cell_defer(cache, new_ocell, false);
1428 }
1429
1430 static int need_commit_due_to_time(struct cache *cache)
1431 {
1432         return jiffies < cache->last_commit_jiffies ||
1433                jiffies > cache->last_commit_jiffies + COMMIT_PERIOD;
1434 }
1435
1436 static int commit_if_needed(struct cache *cache)
1437 {
1438         int r = 0;
1439
1440         if ((cache->commit_requested || need_commit_due_to_time(cache)) &&
1441             dm_cache_changed_this_transaction(cache->cmd)) {
1442                 atomic_inc(&cache->stats.commit_count);
1443                 cache->commit_requested = false;
1444                 r = dm_cache_commit(cache->cmd, false);
1445                 cache->last_commit_jiffies = jiffies;
1446         }
1447
1448         return r;
1449 }
1450
1451 static void process_deferred_bios(struct cache *cache)
1452 {
1453         unsigned long flags;
1454         struct bio_list bios;
1455         struct bio *bio;
1456         struct prealloc structs;
1457
1458         memset(&structs, 0, sizeof(structs));
1459         bio_list_init(&bios);
1460
1461         spin_lock_irqsave(&cache->lock, flags);
1462         bio_list_merge(&bios, &cache->deferred_bios);
1463         bio_list_init(&cache->deferred_bios);
1464         spin_unlock_irqrestore(&cache->lock, flags);
1465
1466         while (!bio_list_empty(&bios)) {
1467                 /*
1468                  * If we've got no free migration structs, and processing
1469                  * this bio might require one, we pause until there are some
1470                  * prepared mappings to process.
1471                  */
1472                 if (prealloc_data_structs(cache, &structs)) {
1473                         spin_lock_irqsave(&cache->lock, flags);
1474                         bio_list_merge(&cache->deferred_bios, &bios);
1475                         spin_unlock_irqrestore(&cache->lock, flags);
1476                         break;
1477                 }
1478
1479                 bio = bio_list_pop(&bios);
1480
1481                 if (bio->bi_rw & REQ_FLUSH)
1482                         process_flush_bio(cache, bio);
1483                 else if (bio->bi_rw & REQ_DISCARD)
1484                         process_discard_bio(cache, bio);
1485                 else
1486                         process_bio(cache, &structs, bio);
1487         }
1488
1489         prealloc_free_structs(cache, &structs);
1490 }
1491
1492 static void process_deferred_flush_bios(struct cache *cache, bool submit_bios)
1493 {
1494         unsigned long flags;
1495         struct bio_list bios;
1496         struct bio *bio;
1497
1498         bio_list_init(&bios);
1499
1500         spin_lock_irqsave(&cache->lock, flags);
1501         bio_list_merge(&bios, &cache->deferred_flush_bios);
1502         bio_list_init(&cache->deferred_flush_bios);
1503         spin_unlock_irqrestore(&cache->lock, flags);
1504
1505         while ((bio = bio_list_pop(&bios)))
1506                 submit_bios ? generic_make_request(bio) : bio_io_error(bio);
1507 }
1508
1509 static void process_deferred_writethrough_bios(struct cache *cache)
1510 {
1511         unsigned long flags;
1512         struct bio_list bios;
1513         struct bio *bio;
1514
1515         bio_list_init(&bios);
1516
1517         spin_lock_irqsave(&cache->lock, flags);
1518         bio_list_merge(&bios, &cache->deferred_writethrough_bios);
1519         bio_list_init(&cache->deferred_writethrough_bios);
1520         spin_unlock_irqrestore(&cache->lock, flags);
1521
1522         while ((bio = bio_list_pop(&bios)))
1523                 generic_make_request(bio);
1524 }
1525
1526 static void writeback_some_dirty_blocks(struct cache *cache)
1527 {
1528         int r = 0;
1529         dm_oblock_t oblock;
1530         dm_cblock_t cblock;
1531         struct prealloc structs;
1532         struct dm_bio_prison_cell *old_ocell;
1533
1534         memset(&structs, 0, sizeof(structs));
1535
1536         while (spare_migration_bandwidth(cache)) {
1537                 if (prealloc_data_structs(cache, &structs))
1538                         break;
1539
1540                 r = policy_writeback_work(cache->policy, &oblock, &cblock);
1541                 if (r)
1542                         break;
1543
1544                 r = get_cell(cache, oblock, &structs, &old_ocell);
1545                 if (r) {
1546                         policy_set_dirty(cache->policy, oblock);
1547                         break;
1548                 }
1549
1550                 writeback(cache, &structs, oblock, cblock, old_ocell);
1551         }
1552
1553         prealloc_free_structs(cache, &structs);
1554 }
1555
1556 /*----------------------------------------------------------------
1557  * Invalidations.
1558  * Dropping something from the cache *without* writing back.
1559  *--------------------------------------------------------------*/
1560
1561 static void process_invalidation_request(struct cache *cache, struct invalidation_request *req)
1562 {
1563         int r = 0;
1564         uint64_t begin = from_cblock(req->cblocks->begin);
1565         uint64_t end = from_cblock(req->cblocks->end);
1566
1567         while (begin != end) {
1568                 r = policy_remove_cblock(cache->policy, to_cblock(begin));
1569                 if (!r) {
1570                         r = dm_cache_remove_mapping(cache->cmd, to_cblock(begin));
1571                         if (r)
1572                                 break;
1573
1574                 } else if (r == -ENODATA) {
1575                         /* harmless, already unmapped */
1576                         r = 0;
1577
1578                 } else {
1579                         DMERR("policy_remove_cblock failed");
1580                         break;
1581                 }
1582
1583                 begin++;
1584         }
1585
1586         cache->commit_requested = true;
1587
1588         req->err = r;
1589         atomic_set(&req->complete, 1);
1590
1591         wake_up(&req->result_wait);
1592 }
1593
1594 static void process_invalidation_requests(struct cache *cache)
1595 {
1596         struct list_head list;
1597         struct invalidation_request *req, *tmp;
1598
1599         INIT_LIST_HEAD(&list);
1600         spin_lock(&cache->invalidation_lock);
1601         list_splice_init(&cache->invalidation_requests, &list);
1602         spin_unlock(&cache->invalidation_lock);
1603
1604         list_for_each_entry_safe (req, tmp, &list, list)
1605                 process_invalidation_request(cache, req);
1606 }
1607
1608 /*----------------------------------------------------------------
1609  * Main worker loop
1610  *--------------------------------------------------------------*/
1611 static bool is_quiescing(struct cache *cache)
1612 {
1613         return atomic_read(&cache->quiescing);
1614 }
1615
1616 static void ack_quiescing(struct cache *cache)
1617 {
1618         if (is_quiescing(cache)) {
1619                 atomic_inc(&cache->quiescing_ack);
1620                 wake_up(&cache->quiescing_wait);
1621         }
1622 }
1623
1624 static void wait_for_quiescing_ack(struct cache *cache)
1625 {
1626         wait_event(cache->quiescing_wait, atomic_read(&cache->quiescing_ack));
1627 }
1628
1629 static void start_quiescing(struct cache *cache)
1630 {
1631         atomic_inc(&cache->quiescing);
1632         wait_for_quiescing_ack(cache);
1633 }
1634
1635 static void stop_quiescing(struct cache *cache)
1636 {
1637         atomic_set(&cache->quiescing, 0);
1638         atomic_set(&cache->quiescing_ack, 0);
1639 }
1640
1641 static void wait_for_migrations(struct cache *cache)
1642 {
1643         wait_event(cache->migration_wait, !atomic_read(&cache->nr_migrations));
1644 }
1645
1646 static void stop_worker(struct cache *cache)
1647 {
1648         cancel_delayed_work(&cache->waker);
1649         flush_workqueue(cache->wq);
1650 }
1651
1652 static void requeue_deferred_io(struct cache *cache)
1653 {
1654         struct bio *bio;
1655         struct bio_list bios;
1656
1657         bio_list_init(&bios);
1658         bio_list_merge(&bios, &cache->deferred_bios);
1659         bio_list_init(&cache->deferred_bios);
1660
1661         while ((bio = bio_list_pop(&bios)))
1662                 bio_endio(bio, DM_ENDIO_REQUEUE);
1663 }
1664
1665 static int more_work(struct cache *cache)
1666 {
1667         if (is_quiescing(cache))
1668                 return !list_empty(&cache->quiesced_migrations) ||
1669                         !list_empty(&cache->completed_migrations) ||
1670                         !list_empty(&cache->need_commit_migrations);
1671         else
1672                 return !bio_list_empty(&cache->deferred_bios) ||
1673                         !bio_list_empty(&cache->deferred_flush_bios) ||
1674                         !bio_list_empty(&cache->deferred_writethrough_bios) ||
1675                         !list_empty(&cache->quiesced_migrations) ||
1676                         !list_empty(&cache->completed_migrations) ||
1677                         !list_empty(&cache->need_commit_migrations) ||
1678                         cache->invalidate;
1679 }
1680
1681 static void do_worker(struct work_struct *ws)
1682 {
1683         struct cache *cache = container_of(ws, struct cache, worker);
1684
1685         do {
1686                 if (!is_quiescing(cache)) {
1687                         writeback_some_dirty_blocks(cache);
1688                         process_deferred_writethrough_bios(cache);
1689                         process_deferred_bios(cache);
1690                         process_invalidation_requests(cache);
1691                 }
1692
1693                 process_migrations(cache, &cache->quiesced_migrations, issue_copy);
1694                 process_migrations(cache, &cache->completed_migrations, complete_migration);
1695
1696                 if (commit_if_needed(cache)) {
1697                         process_deferred_flush_bios(cache, false);
1698
1699                         /*
1700                          * FIXME: rollback metadata or just go into a
1701                          * failure mode and error everything
1702                          */
1703                 } else {
1704                         process_deferred_flush_bios(cache, true);
1705                         process_migrations(cache, &cache->need_commit_migrations,
1706                                            migration_success_post_commit);
1707                 }
1708
1709                 ack_quiescing(cache);
1710
1711         } while (more_work(cache));
1712 }
1713
1714 /*
1715  * We want to commit periodically so that not too much
1716  * unwritten metadata builds up.
1717  */
1718 static void do_waker(struct work_struct *ws)
1719 {
1720         struct cache *cache = container_of(to_delayed_work(ws), struct cache, waker);
1721         policy_tick(cache->policy);
1722         wake_worker(cache);
1723         queue_delayed_work(cache->wq, &cache->waker, COMMIT_PERIOD);
1724 }
1725
1726 /*----------------------------------------------------------------*/
1727
1728 static int is_congested(struct dm_dev *dev, int bdi_bits)
1729 {
1730         struct request_queue *q = bdev_get_queue(dev->bdev);
1731         return bdi_congested(&q->backing_dev_info, bdi_bits);
1732 }
1733
1734 static int cache_is_congested(struct dm_target_callbacks *cb, int bdi_bits)
1735 {
1736         struct cache *cache = container_of(cb, struct cache, callbacks);
1737
1738         return is_congested(cache->origin_dev, bdi_bits) ||
1739                 is_congested(cache->cache_dev, bdi_bits);
1740 }
1741
1742 /*----------------------------------------------------------------
1743  * Target methods
1744  *--------------------------------------------------------------*/
1745
1746 /*
1747  * This function gets called on the error paths of the constructor, so we
1748  * have to cope with a partially initialised struct.
1749  */
1750 static void destroy(struct cache *cache)
1751 {
1752         unsigned i;
1753
1754         if (cache->next_migration)
1755                 mempool_free(cache->next_migration, cache->migration_pool);
1756
1757         if (cache->migration_pool)
1758                 mempool_destroy(cache->migration_pool);
1759
1760         if (cache->all_io_ds)
1761                 dm_deferred_set_destroy(cache->all_io_ds);
1762
1763         if (cache->prison)
1764                 dm_bio_prison_destroy(cache->prison);
1765
1766         if (cache->wq)
1767                 destroy_workqueue(cache->wq);
1768
1769         if (cache->dirty_bitset)
1770                 free_bitset(cache->dirty_bitset);
1771
1772         if (cache->discard_bitset)
1773                 free_bitset(cache->discard_bitset);
1774
1775         if (cache->copier)
1776                 dm_kcopyd_client_destroy(cache->copier);
1777
1778         if (cache->cmd)
1779                 dm_cache_metadata_close(cache->cmd);
1780
1781         if (cache->metadata_dev)
1782                 dm_put_device(cache->ti, cache->metadata_dev);
1783
1784         if (cache->origin_dev)
1785                 dm_put_device(cache->ti, cache->origin_dev);
1786
1787         if (cache->cache_dev)
1788                 dm_put_device(cache->ti, cache->cache_dev);
1789
1790         if (cache->policy)
1791                 dm_cache_policy_destroy(cache->policy);
1792
1793         for (i = 0; i < cache->nr_ctr_args ; i++)
1794                 kfree(cache->ctr_args[i]);
1795         kfree(cache->ctr_args);
1796
1797         kfree(cache);
1798 }
1799
1800 static void cache_dtr(struct dm_target *ti)
1801 {
1802         struct cache *cache = ti->private;
1803
1804         destroy(cache);
1805 }
1806
1807 static sector_t get_dev_size(struct dm_dev *dev)
1808 {
1809         return i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT;
1810 }
1811
1812 /*----------------------------------------------------------------*/
1813
1814 /*
1815  * Construct a cache device mapping.
1816  *
1817  * cache <metadata dev> <cache dev> <origin dev> <block size>
1818  *       <#feature args> [<feature arg>]*
1819  *       <policy> <#policy args> [<policy arg>]*
1820  *
1821  * metadata dev    : fast device holding the persistent metadata
1822  * cache dev       : fast device holding cached data blocks
1823  * origin dev      : slow device holding original data blocks
1824  * block size      : cache unit size in sectors
1825  *
1826  * #feature args   : number of feature arguments passed
1827  * feature args    : writethrough.  (The default is writeback.)
1828  *
1829  * policy          : the replacement policy to use
1830  * #policy args    : an even number of policy arguments corresponding
1831  *                   to key/value pairs passed to the policy
1832  * policy args     : key/value pairs passed to the policy
1833  *                   E.g. 'sequential_threshold 1024'
1834  *                   See cache-policies.txt for details.
1835  *
1836  * Optional feature arguments are:
1837  *   writethrough  : write through caching that prohibits cache block
1838  *                   content from being different from origin block content.
1839  *                   Without this argument, the default behaviour is to write
1840  *                   back cache block contents later for performance reasons,
1841  *                   so they may differ from the corresponding origin blocks.
1842  */
1843 struct cache_args {
1844         struct dm_target *ti;
1845
1846         struct dm_dev *metadata_dev;
1847
1848         struct dm_dev *cache_dev;
1849         sector_t cache_sectors;
1850
1851         struct dm_dev *origin_dev;
1852         sector_t origin_sectors;
1853
1854         uint32_t block_size;
1855
1856         const char *policy_name;
1857         int policy_argc;
1858         const char **policy_argv;
1859
1860         struct cache_features features;
1861 };
1862
1863 static void destroy_cache_args(struct cache_args *ca)
1864 {
1865         if (ca->metadata_dev)
1866                 dm_put_device(ca->ti, ca->metadata_dev);
1867
1868         if (ca->cache_dev)
1869                 dm_put_device(ca->ti, ca->cache_dev);
1870
1871         if (ca->origin_dev)
1872                 dm_put_device(ca->ti, ca->origin_dev);
1873
1874         kfree(ca);
1875 }
1876
1877 static bool at_least_one_arg(struct dm_arg_set *as, char **error)
1878 {
1879         if (!as->argc) {
1880                 *error = "Insufficient args";
1881                 return false;
1882         }
1883
1884         return true;
1885 }
1886
1887 static int parse_metadata_dev(struct cache_args *ca, struct dm_arg_set *as,
1888                               char **error)
1889 {
1890         int r;
1891         sector_t metadata_dev_size;
1892         char b[BDEVNAME_SIZE];
1893
1894         if (!at_least_one_arg(as, error))
1895                 return -EINVAL;
1896
1897         r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
1898                           &ca->metadata_dev);
1899         if (r) {
1900                 *error = "Error opening metadata device";
1901                 return r;
1902         }
1903
1904         metadata_dev_size = get_dev_size(ca->metadata_dev);
1905         if (metadata_dev_size > DM_CACHE_METADATA_MAX_SECTORS_WARNING)
1906                 DMWARN("Metadata device %s is larger than %u sectors: excess space will not be used.",
1907                        bdevname(ca->metadata_dev->bdev, b), THIN_METADATA_MAX_SECTORS);
1908
1909         return 0;
1910 }
1911
1912 static int parse_cache_dev(struct cache_args *ca, struct dm_arg_set *as,
1913                            char **error)
1914 {
1915         int r;
1916
1917         if (!at_least_one_arg(as, error))
1918                 return -EINVAL;
1919
1920         r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
1921                           &ca->cache_dev);
1922         if (r) {
1923                 *error = "Error opening cache device";
1924                 return r;
1925         }
1926         ca->cache_sectors = get_dev_size(ca->cache_dev);
1927
1928         return 0;
1929 }
1930
1931 static int parse_origin_dev(struct cache_args *ca, struct dm_arg_set *as,
1932                             char **error)
1933 {
1934         int r;
1935
1936         if (!at_least_one_arg(as, error))
1937                 return -EINVAL;
1938
1939         r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
1940                           &ca->origin_dev);
1941         if (r) {
1942                 *error = "Error opening origin device";
1943                 return r;
1944         }
1945
1946         ca->origin_sectors = get_dev_size(ca->origin_dev);
1947         if (ca->ti->len > ca->origin_sectors) {
1948                 *error = "Device size larger than cached device";
1949                 return -EINVAL;
1950         }
1951
1952         return 0;
1953 }
1954
1955 static int parse_block_size(struct cache_args *ca, struct dm_arg_set *as,
1956                             char **error)
1957 {
1958         unsigned long block_size;
1959
1960         if (!at_least_one_arg(as, error))
1961                 return -EINVAL;
1962
1963         if (kstrtoul(dm_shift_arg(as), 10, &block_size) || !block_size ||
1964             block_size < DATA_DEV_BLOCK_SIZE_MIN_SECTORS ||
1965             block_size > DATA_DEV_BLOCK_SIZE_MAX_SECTORS ||
1966             block_size & (DATA_DEV_BLOCK_SIZE_MIN_SECTORS - 1)) {
1967                 *error = "Invalid data block size";
1968                 return -EINVAL;
1969         }
1970
1971         if (block_size > ca->cache_sectors) {
1972                 *error = "Data block size is larger than the cache device";
1973                 return -EINVAL;
1974         }
1975
1976         ca->block_size = block_size;
1977
1978         return 0;
1979 }
1980
1981 static void init_features(struct cache_features *cf)
1982 {
1983         cf->mode = CM_WRITE;
1984         cf->io_mode = CM_IO_WRITEBACK;
1985 }
1986
1987 static int parse_features(struct cache_args *ca, struct dm_arg_set *as,
1988                           char **error)
1989 {
1990         static struct dm_arg _args[] = {
1991                 {0, 1, "Invalid number of cache feature arguments"},
1992         };
1993
1994         int r;
1995         unsigned argc;
1996         const char *arg;
1997         struct cache_features *cf = &ca->features;
1998
1999         init_features(cf);
2000
2001         r = dm_read_arg_group(_args, as, &argc, error);
2002         if (r)
2003                 return -EINVAL;
2004
2005         while (argc--) {
2006                 arg = dm_shift_arg(as);
2007
2008                 if (!strcasecmp(arg, "writeback"))
2009                         cf->io_mode = CM_IO_WRITEBACK;
2010
2011                 else if (!strcasecmp(arg, "writethrough"))
2012                         cf->io_mode = CM_IO_WRITETHROUGH;
2013
2014                 else if (!strcasecmp(arg, "passthrough"))
2015                         cf->io_mode = CM_IO_PASSTHROUGH;
2016
2017                 else {
2018                         *error = "Unrecognised cache feature requested";
2019                         return -EINVAL;
2020                 }
2021         }
2022
2023         return 0;
2024 }
2025
2026 static int parse_policy(struct cache_args *ca, struct dm_arg_set *as,
2027                         char **error)
2028 {
2029         static struct dm_arg _args[] = {
2030                 {0, 1024, "Invalid number of policy arguments"},
2031         };
2032
2033         int r;
2034
2035         if (!at_least_one_arg(as, error))
2036                 return -EINVAL;
2037
2038         ca->policy_name = dm_shift_arg(as);
2039
2040         r = dm_read_arg_group(_args, as, &ca->policy_argc, error);
2041         if (r)
2042                 return -EINVAL;
2043
2044         ca->policy_argv = (const char **)as->argv;
2045         dm_consume_args(as, ca->policy_argc);
2046
2047         return 0;
2048 }
2049
2050 static int parse_cache_args(struct cache_args *ca, int argc, char **argv,
2051                             char **error)
2052 {
2053         int r;
2054         struct dm_arg_set as;
2055
2056         as.argc = argc;
2057         as.argv = argv;
2058
2059         r = parse_metadata_dev(ca, &as, error);
2060         if (r)
2061                 return r;
2062
2063         r = parse_cache_dev(ca, &as, error);
2064         if (r)
2065                 return r;
2066
2067         r = parse_origin_dev(ca, &as, error);
2068         if (r)
2069                 return r;
2070
2071         r = parse_block_size(ca, &as, error);
2072         if (r)
2073                 return r;
2074
2075         r = parse_features(ca, &as, error);
2076         if (r)
2077                 return r;
2078
2079         r = parse_policy(ca, &as, error);
2080         if (r)
2081                 return r;
2082
2083         return 0;
2084 }
2085
2086 /*----------------------------------------------------------------*/
2087
2088 static struct kmem_cache *migration_cache;
2089
2090 #define NOT_CORE_OPTION 1
2091
2092 static int process_config_option(struct cache *cache, const char *key, const char *value)
2093 {
2094         unsigned long tmp;
2095
2096         if (!strcasecmp(key, "migration_threshold")) {
2097                 if (kstrtoul(value, 10, &tmp))
2098                         return -EINVAL;
2099
2100                 cache->migration_threshold = tmp;
2101                 return 0;
2102         }
2103
2104         return NOT_CORE_OPTION;
2105 }
2106
2107 static int set_config_value(struct cache *cache, const char *key, const char *value)
2108 {
2109         int r = process_config_option(cache, key, value);
2110
2111         if (r == NOT_CORE_OPTION)
2112                 r = policy_set_config_value(cache->policy, key, value);
2113
2114         if (r)
2115                 DMWARN("bad config value for %s: %s", key, value);
2116
2117         return r;
2118 }
2119
2120 static int set_config_values(struct cache *cache, int argc, const char **argv)
2121 {
2122         int r = 0;
2123
2124         if (argc & 1) {
2125                 DMWARN("Odd number of policy arguments given but they should be <key> <value> pairs.");
2126                 return -EINVAL;
2127         }
2128
2129         while (argc) {
2130                 r = set_config_value(cache, argv[0], argv[1]);
2131                 if (r)
2132                         break;
2133
2134                 argc -= 2;
2135                 argv += 2;
2136         }
2137
2138         return r;
2139 }
2140
2141 static int create_cache_policy(struct cache *cache, struct cache_args *ca,
2142                                char **error)
2143 {
2144         struct dm_cache_policy *p = dm_cache_policy_create(ca->policy_name,
2145                                                            cache->cache_size,
2146                                                            cache->origin_sectors,
2147                                                            cache->sectors_per_block);
2148         if (IS_ERR(p)) {
2149                 *error = "Error creating cache's policy";
2150                 return PTR_ERR(p);
2151         }
2152         cache->policy = p;
2153
2154         return 0;
2155 }
2156
2157 #define DEFAULT_MIGRATION_THRESHOLD 2048
2158
2159 static int cache_create(struct cache_args *ca, struct cache **result)
2160 {
2161         int r = 0;
2162         char **error = &ca->ti->error;
2163         struct cache *cache;
2164         struct dm_target *ti = ca->ti;
2165         dm_block_t origin_blocks;
2166         struct dm_cache_metadata *cmd;
2167         bool may_format = ca->features.mode == CM_WRITE;
2168
2169         cache = kzalloc(sizeof(*cache), GFP_KERNEL);
2170         if (!cache)
2171                 return -ENOMEM;
2172
2173         cache->ti = ca->ti;
2174         ti->private = cache;
2175         ti->num_flush_bios = 2;
2176         ti->flush_supported = true;
2177
2178         ti->num_discard_bios = 1;
2179         ti->discards_supported = true;
2180         ti->discard_zeroes_data_unsupported = true;
2181         /* Discard bios must be split on a block boundary */
2182         ti->split_discard_bios = true;
2183
2184         cache->features = ca->features;
2185         ti->per_bio_data_size = get_per_bio_data_size(cache);
2186
2187         cache->callbacks.congested_fn = cache_is_congested;
2188         dm_table_add_target_callbacks(ti->table, &cache->callbacks);
2189
2190         cache->metadata_dev = ca->metadata_dev;
2191         cache->origin_dev = ca->origin_dev;
2192         cache->cache_dev = ca->cache_dev;
2193
2194         ca->metadata_dev = ca->origin_dev = ca->cache_dev = NULL;
2195
2196         /* FIXME: factor out this whole section */
2197         origin_blocks = cache->origin_sectors = ca->origin_sectors;
2198         origin_blocks = block_div(origin_blocks, ca->block_size);
2199         cache->origin_blocks = to_oblock(origin_blocks);
2200
2201         cache->sectors_per_block = ca->block_size;
2202         if (dm_set_target_max_io_len(ti, cache->sectors_per_block)) {
2203                 r = -EINVAL;
2204                 goto bad;
2205         }
2206
2207         if (ca->block_size & (ca->block_size - 1)) {
2208                 dm_block_t cache_size = ca->cache_sectors;
2209
2210                 cache->sectors_per_block_shift = -1;
2211                 cache_size = block_div(cache_size, ca->block_size);
2212                 cache->cache_size = to_cblock(cache_size);
2213         } else {
2214                 cache->sectors_per_block_shift = __ffs(ca->block_size);
2215                 cache->cache_size = to_cblock(ca->cache_sectors >> cache->sectors_per_block_shift);
2216         }
2217
2218         r = create_cache_policy(cache, ca, error);
2219         if (r)
2220                 goto bad;
2221
2222         cache->policy_nr_args = ca->policy_argc;
2223         cache->migration_threshold = DEFAULT_MIGRATION_THRESHOLD;
2224
2225         r = set_config_values(cache, ca->policy_argc, ca->policy_argv);
2226         if (r) {
2227                 *error = "Error setting cache policy's config values";
2228                 goto bad;
2229         }
2230
2231         cmd = dm_cache_metadata_open(cache->metadata_dev->bdev,
2232                                      ca->block_size, may_format,
2233                                      dm_cache_policy_get_hint_size(cache->policy));
2234         if (IS_ERR(cmd)) {
2235                 *error = "Error creating metadata object";
2236                 r = PTR_ERR(cmd);
2237                 goto bad;
2238         }
2239         cache->cmd = cmd;
2240
2241         if (passthrough_mode(&cache->features)) {
2242                 bool all_clean;
2243
2244                 r = dm_cache_metadata_all_clean(cache->cmd, &all_clean);
2245                 if (r) {
2246                         *error = "dm_cache_metadata_all_clean() failed";
2247                         goto bad;
2248                 }
2249
2250                 if (!all_clean) {
2251                         *error = "Cannot enter passthrough mode unless all blocks are clean";
2252                         r = -EINVAL;
2253                         goto bad;
2254                 }
2255         }
2256
2257         spin_lock_init(&cache->lock);
2258         bio_list_init(&cache->deferred_bios);
2259         bio_list_init(&cache->deferred_flush_bios);
2260         bio_list_init(&cache->deferred_writethrough_bios);
2261         INIT_LIST_HEAD(&cache->quiesced_migrations);
2262         INIT_LIST_HEAD(&cache->completed_migrations);
2263         INIT_LIST_HEAD(&cache->need_commit_migrations);
2264         atomic_set(&cache->nr_migrations, 0);
2265         init_waitqueue_head(&cache->migration_wait);
2266
2267         init_waitqueue_head(&cache->quiescing_wait);
2268         atomic_set(&cache->quiescing, 0);
2269         atomic_set(&cache->quiescing_ack, 0);
2270
2271         r = -ENOMEM;
2272         cache->nr_dirty = 0;
2273         cache->dirty_bitset = alloc_bitset(from_cblock(cache->cache_size));
2274         if (!cache->dirty_bitset) {
2275                 *error = "could not allocate dirty bitset";
2276                 goto bad;
2277         }
2278         clear_bitset(cache->dirty_bitset, from_cblock(cache->cache_size));
2279
2280         cache->discard_nr_blocks = cache->origin_blocks;
2281         cache->discard_bitset = alloc_bitset(from_oblock(cache->discard_nr_blocks));
2282         if (!cache->discard_bitset) {
2283                 *error = "could not allocate discard bitset";
2284                 goto bad;
2285         }
2286         clear_bitset(cache->discard_bitset, from_oblock(cache->discard_nr_blocks));
2287
2288         cache->copier = dm_kcopyd_client_create(&dm_kcopyd_throttle);
2289         if (IS_ERR(cache->copier)) {
2290                 *error = "could not create kcopyd client";
2291                 r = PTR_ERR(cache->copier);
2292                 goto bad;
2293         }
2294
2295         cache->wq = alloc_ordered_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM);
2296         if (!cache->wq) {
2297                 *error = "could not create workqueue for metadata object";
2298                 goto bad;
2299         }
2300         INIT_WORK(&cache->worker, do_worker);
2301         INIT_DELAYED_WORK(&cache->waker, do_waker);
2302         cache->last_commit_jiffies = jiffies;
2303
2304         cache->prison = dm_bio_prison_create(PRISON_CELLS);
2305         if (!cache->prison) {
2306                 *error = "could not create bio prison";
2307                 goto bad;
2308         }
2309
2310         cache->all_io_ds = dm_deferred_set_create();
2311         if (!cache->all_io_ds) {
2312                 *error = "could not create all_io deferred set";
2313                 goto bad;
2314         }
2315
2316         cache->migration_pool = mempool_create_slab_pool(MIGRATION_POOL_SIZE,
2317                                                          migration_cache);
2318         if (!cache->migration_pool) {
2319                 *error = "Error creating cache's migration mempool";
2320                 goto bad;
2321         }
2322
2323         cache->next_migration = NULL;
2324
2325         cache->need_tick_bio = true;
2326         cache->sized = false;
2327         cache->invalidate = false;
2328         cache->commit_requested = false;
2329         cache->loaded_mappings = false;
2330         cache->loaded_discards = false;
2331
2332         load_stats(cache);
2333
2334         atomic_set(&cache->stats.demotion, 0);
2335         atomic_set(&cache->stats.promotion, 0);
2336         atomic_set(&cache->stats.copies_avoided, 0);
2337         atomic_set(&cache->stats.cache_cell_clash, 0);
2338         atomic_set(&cache->stats.commit_count, 0);
2339         atomic_set(&cache->stats.discard_count, 0);
2340
2341         spin_lock_init(&cache->invalidation_lock);
2342         INIT_LIST_HEAD(&cache->invalidation_requests);
2343
2344         *result = cache;
2345         return 0;
2346
2347 bad:
2348         destroy(cache);
2349         return r;
2350 }
2351
2352 static int copy_ctr_args(struct cache *cache, int argc, const char **argv)
2353 {
2354         unsigned i;
2355         const char **copy;
2356
2357         copy = kcalloc(argc, sizeof(*copy), GFP_KERNEL);
2358         if (!copy)
2359                 return -ENOMEM;
2360         for (i = 0; i < argc; i++) {
2361                 copy[i] = kstrdup(argv[i], GFP_KERNEL);
2362                 if (!copy[i]) {
2363                         while (i--)
2364                                 kfree(copy[i]);
2365                         kfree(copy);
2366                         return -ENOMEM;
2367                 }
2368         }
2369
2370         cache->nr_ctr_args = argc;
2371         cache->ctr_args = copy;
2372
2373         return 0;
2374 }
2375
2376 static int cache_ctr(struct dm_target *ti, unsigned argc, char **argv)
2377 {
2378         int r = -EINVAL;
2379         struct cache_args *ca;
2380         struct cache *cache = NULL;
2381
2382         ca = kzalloc(sizeof(*ca), GFP_KERNEL);
2383         if (!ca) {
2384                 ti->error = "Error allocating memory for cache";
2385                 return -ENOMEM;
2386         }
2387         ca->ti = ti;
2388
2389         r = parse_cache_args(ca, argc, argv, &ti->error);
2390         if (r)
2391                 goto out;
2392
2393         r = cache_create(ca, &cache);
2394         if (r)
2395                 goto out;
2396
2397         r = copy_ctr_args(cache, argc - 3, (const char **)argv + 3);
2398         if (r) {
2399                 destroy(cache);
2400                 goto out;
2401         }
2402
2403         ti->private = cache;
2404
2405 out:
2406         destroy_cache_args(ca);
2407         return r;
2408 }
2409
2410 static int cache_map(struct dm_target *ti, struct bio *bio)
2411 {
2412         struct cache *cache = ti->private;
2413
2414         int r;
2415         dm_oblock_t block = get_bio_block(cache, bio);
2416         size_t pb_data_size = get_per_bio_data_size(cache);
2417         bool can_migrate = false;
2418         bool discarded_block;
2419         struct dm_bio_prison_cell *cell;
2420         struct policy_result lookup_result;
2421         struct per_bio_data *pb = init_per_bio_data(bio, pb_data_size);
2422
2423         if (unlikely(from_oblock(block) >= from_oblock(cache->origin_blocks))) {
2424                 /*
2425                  * This can only occur if the io goes to a partial block at
2426                  * the end of the origin device.  We don't cache these.
2427                  * Just remap to the origin and carry on.
2428                  */
2429                 remap_to_origin(cache, bio);
2430                 return DM_MAPIO_REMAPPED;
2431         }
2432
2433         if (bio->bi_rw & (REQ_FLUSH | REQ_FUA | REQ_DISCARD)) {
2434                 defer_bio(cache, bio);
2435                 return DM_MAPIO_SUBMITTED;
2436         }
2437
2438         /*
2439          * Check to see if that block is currently migrating.
2440          */
2441         cell = alloc_prison_cell(cache);
2442         if (!cell) {
2443                 defer_bio(cache, bio);
2444                 return DM_MAPIO_SUBMITTED;
2445         }
2446
2447         r = bio_detain(cache, block, bio, cell,
2448                        (cell_free_fn) free_prison_cell,
2449                        cache, &cell);
2450         if (r) {
2451                 if (r < 0)
2452                         defer_bio(cache, bio);
2453
2454                 return DM_MAPIO_SUBMITTED;
2455         }
2456
2457         discarded_block = is_discarded_oblock(cache, block);
2458
2459         r = policy_map(cache->policy, block, false, can_migrate, discarded_block,
2460                        bio, &lookup_result);
2461         if (r == -EWOULDBLOCK) {
2462                 cell_defer(cache, cell, true);
2463                 return DM_MAPIO_SUBMITTED;
2464
2465         } else if (r) {
2466                 DMERR_LIMIT("Unexpected return from cache replacement policy: %d", r);
2467                 bio_io_error(bio);
2468                 return DM_MAPIO_SUBMITTED;
2469         }
2470
2471         r = DM_MAPIO_REMAPPED;
2472         switch (lookup_result.op) {
2473         case POLICY_HIT:
2474                 if (passthrough_mode(&cache->features)) {
2475                         if (bio_data_dir(bio) == WRITE) {
2476                                 /*
2477                                  * We need to invalidate this block, so
2478                                  * defer for the worker thread.
2479                                  */
2480                                 cell_defer(cache, cell, true);
2481                                 r = DM_MAPIO_SUBMITTED;
2482
2483                         } else {
2484                                 pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
2485                                 inc_miss_counter(cache, bio);
2486                                 remap_to_origin_clear_discard(cache, bio, block);
2487
2488                                 cell_defer(cache, cell, false);
2489                         }
2490
2491                 } else {
2492                         inc_hit_counter(cache, bio);
2493                         pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
2494
2495                         if (bio_data_dir(bio) == WRITE && writethrough_mode(&cache->features) &&
2496                             !is_dirty(cache, lookup_result.cblock))
2497                                 remap_to_origin_then_cache(cache, bio, block, lookup_result.cblock);
2498                         else
2499                                 remap_to_cache_dirty(cache, bio, block, lookup_result.cblock);
2500
2501                         cell_defer(cache, cell, false);
2502                 }
2503                 break;
2504
2505         case POLICY_MISS:
2506                 inc_miss_counter(cache, bio);
2507                 pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
2508
2509                 if (pb->req_nr != 0) {
2510                         /*
2511                          * This is a duplicate writethrough io that is no
2512                          * longer needed because the block has been demoted.
2513                          */
2514                         bio_endio(bio, 0);
2515                         cell_defer(cache, cell, false);
2516                         return DM_MAPIO_SUBMITTED;
2517                 } else {
2518                         remap_to_origin_clear_discard(cache, bio, block);
2519                         cell_defer(cache, cell, false);
2520                 }
2521                 break;
2522
2523         default:
2524                 DMERR_LIMIT("%s: erroring bio: unknown policy op: %u", __func__,
2525                             (unsigned) lookup_result.op);
2526                 bio_io_error(bio);
2527                 r = DM_MAPIO_SUBMITTED;
2528         }
2529
2530         return r;
2531 }
2532
2533 static int cache_end_io(struct dm_target *ti, struct bio *bio, int error)
2534 {
2535         struct cache *cache = ti->private;
2536         unsigned long flags;
2537         size_t pb_data_size = get_per_bio_data_size(cache);
2538         struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
2539
2540         if (pb->tick) {
2541                 policy_tick(cache->policy);
2542
2543                 spin_lock_irqsave(&cache->lock, flags);
2544                 cache->need_tick_bio = true;
2545                 spin_unlock_irqrestore(&cache->lock, flags);
2546         }
2547
2548         check_for_quiesced_migrations(cache, pb);
2549
2550         return 0;
2551 }
2552
2553 static int write_dirty_bitset(struct cache *cache)
2554 {
2555         unsigned i, r;
2556
2557         for (i = 0; i < from_cblock(cache->cache_size); i++) {
2558                 r = dm_cache_set_dirty(cache->cmd, to_cblock(i),
2559                                        is_dirty(cache, to_cblock(i)));
2560                 if (r)
2561                         return r;
2562         }
2563
2564         return 0;
2565 }
2566
2567 static int write_discard_bitset(struct cache *cache)
2568 {
2569         unsigned i, r;
2570
2571         r = dm_cache_discard_bitset_resize(cache->cmd, cache->sectors_per_block,
2572                                            cache->origin_blocks);
2573         if (r) {
2574                 DMERR("could not resize on-disk discard bitset");
2575                 return r;
2576         }
2577
2578         for (i = 0; i < from_oblock(cache->discard_nr_blocks); i++) {
2579                 r = dm_cache_set_discard(cache->cmd, to_oblock(i),
2580                                          is_discarded(cache, to_oblock(i)));
2581                 if (r)
2582                         return r;
2583         }
2584
2585         return 0;
2586 }
2587
2588 /*
2589  * returns true on success
2590  */
2591 static bool sync_metadata(struct cache *cache)
2592 {
2593         int r1, r2, r3, r4;
2594
2595         r1 = write_dirty_bitset(cache);
2596         if (r1)
2597                 DMERR("could not write dirty bitset");
2598
2599         r2 = write_discard_bitset(cache);
2600         if (r2)
2601                 DMERR("could not write discard bitset");
2602
2603         save_stats(cache);
2604
2605         r3 = dm_cache_write_hints(cache->cmd, cache->policy);
2606         if (r3)
2607                 DMERR("could not write hints");
2608
2609         /*
2610          * If writing the above metadata failed, we still commit, but don't
2611          * set the clean shutdown flag.  This will effectively force every
2612          * dirty bit to be set on reload.
2613          */
2614         r4 = dm_cache_commit(cache->cmd, !r1 && !r2 && !r3);
2615         if (r4)
2616                 DMERR("could not write cache metadata.  Data loss may occur.");
2617
2618         return !r1 && !r2 && !r3 && !r4;
2619 }
2620
2621 static void cache_postsuspend(struct dm_target *ti)
2622 {
2623         struct cache *cache = ti->private;
2624
2625         start_quiescing(cache);
2626         wait_for_migrations(cache);
2627         stop_worker(cache);
2628         requeue_deferred_io(cache);
2629         stop_quiescing(cache);
2630
2631         (void) sync_metadata(cache);
2632 }
2633
2634 static int load_mapping(void *context, dm_oblock_t oblock, dm_cblock_t cblock,
2635                         bool dirty, uint32_t hint, bool hint_valid)
2636 {
2637         int r;
2638         struct cache *cache = context;
2639
2640         r = policy_load_mapping(cache->policy, oblock, cblock, hint, hint_valid);
2641         if (r)
2642                 return r;
2643
2644         if (dirty)
2645                 set_dirty(cache, oblock, cblock);
2646         else
2647                 clear_dirty(cache, oblock, cblock);
2648
2649         return 0;
2650 }
2651
2652 static int load_discard(void *context, sector_t discard_block_size,
2653                         dm_oblock_t oblock, bool discard)
2654 {
2655         struct cache *cache = context;
2656
2657         if (discard)
2658                 set_discard(cache, oblock);
2659         else
2660                 clear_discard(cache, oblock);
2661
2662         return 0;
2663 }
2664
2665 static dm_cblock_t get_cache_dev_size(struct cache *cache)
2666 {
2667         sector_t size = get_dev_size(cache->cache_dev);
2668         (void) sector_div(size, cache->sectors_per_block);
2669         return to_cblock(size);
2670 }
2671
2672 static bool can_resize(struct cache *cache, dm_cblock_t new_size)
2673 {
2674         if (from_cblock(new_size) > from_cblock(cache->cache_size))
2675                 return true;
2676
2677         /*
2678          * We can't drop a dirty block when shrinking the cache.
2679          */
2680         while (from_cblock(new_size) < from_cblock(cache->cache_size)) {
2681                 new_size = to_cblock(from_cblock(new_size) + 1);
2682                 if (is_dirty(cache, new_size)) {
2683                         DMERR("unable to shrink cache; cache block %llu is dirty",
2684                               (unsigned long long) from_cblock(new_size));
2685                         return false;
2686                 }
2687         }
2688
2689         return true;
2690 }
2691
2692 static int resize_cache_dev(struct cache *cache, dm_cblock_t new_size)
2693 {
2694         int r;
2695
2696         r = dm_cache_resize(cache->cmd, new_size);
2697         if (r) {
2698                 DMERR("could not resize cache metadata");
2699                 return r;
2700         }
2701
2702         cache->cache_size = new_size;
2703
2704         return 0;
2705 }
2706
2707 static int cache_preresume(struct dm_target *ti)
2708 {
2709         int r = 0;
2710         struct cache *cache = ti->private;
2711         dm_cblock_t csize = get_cache_dev_size(cache);
2712
2713         /*
2714          * Check to see if the cache has resized.
2715          */
2716         if (!cache->sized) {
2717                 r = resize_cache_dev(cache, csize);
2718                 if (r)
2719                         return r;
2720
2721                 cache->sized = true;
2722
2723         } else if (csize != cache->cache_size) {
2724                 if (!can_resize(cache, csize))
2725                         return -EINVAL;
2726
2727                 r = resize_cache_dev(cache, csize);
2728                 if (r)
2729                         return r;
2730         }
2731
2732         if (!cache->loaded_mappings) {
2733                 r = dm_cache_load_mappings(cache->cmd, cache->policy,
2734                                            load_mapping, cache);
2735                 if (r) {
2736                         DMERR("could not load cache mappings");
2737                         return r;
2738                 }
2739
2740                 cache->loaded_mappings = true;
2741         }
2742
2743         if (!cache->loaded_discards) {
2744                 r = dm_cache_load_discards(cache->cmd, load_discard, cache);
2745                 if (r) {
2746                         DMERR("could not load origin discards");
2747                         return r;
2748                 }
2749
2750                 cache->loaded_discards = true;
2751         }
2752
2753         return r;
2754 }
2755
2756 static void cache_resume(struct dm_target *ti)
2757 {
2758         struct cache *cache = ti->private;
2759
2760         cache->need_tick_bio = true;
2761         do_waker(&cache->waker.work);
2762 }
2763
2764 /*
2765  * Status format:
2766  *
2767  * <metadata block size> <#used metadata blocks>/<#total metadata blocks>
2768  * <cache block size> <#used cache blocks>/<#total cache blocks>
2769  * <#read hits> <#read misses> <#write hits> <#write misses>
2770  * <#demotions> <#promotions> <#dirty>
2771  * <#features> <features>*
2772  * <#core args> <core args>
2773  * <policy name> <#policy args> <policy args>*
2774  */
2775 static void cache_status(struct dm_target *ti, status_type_t type,
2776                          unsigned status_flags, char *result, unsigned maxlen)
2777 {
2778         int r = 0;
2779         unsigned i;
2780         ssize_t sz = 0;
2781         dm_block_t nr_free_blocks_metadata = 0;
2782         dm_block_t nr_blocks_metadata = 0;
2783         char buf[BDEVNAME_SIZE];
2784         struct cache *cache = ti->private;
2785         dm_cblock_t residency;
2786
2787         switch (type) {
2788         case STATUSTYPE_INFO:
2789                 /* Commit to ensure statistics aren't out-of-date */
2790                 if (!(status_flags & DM_STATUS_NOFLUSH_FLAG) && !dm_suspended(ti)) {
2791                         r = dm_cache_commit(cache->cmd, false);
2792                         if (r)
2793                                 DMERR("could not commit metadata for accurate status");
2794                 }
2795
2796                 r = dm_cache_get_free_metadata_block_count(cache->cmd,
2797                                                            &nr_free_blocks_metadata);
2798                 if (r) {
2799                         DMERR("could not get metadata free block count");
2800                         goto err;
2801                 }
2802
2803                 r = dm_cache_get_metadata_dev_size(cache->cmd, &nr_blocks_metadata);
2804                 if (r) {
2805                         DMERR("could not get metadata device size");
2806                         goto err;
2807                 }
2808
2809                 residency = policy_residency(cache->policy);
2810
2811                 DMEMIT("%u %llu/%llu %u %llu/%llu %u %u %u %u %u %u %llu ",
2812                        (unsigned)(DM_CACHE_METADATA_BLOCK_SIZE >> SECTOR_SHIFT),
2813                        (unsigned long long)(nr_blocks_metadata - nr_free_blocks_metadata),
2814                        (unsigned long long)nr_blocks_metadata,
2815                        cache->sectors_per_block,
2816                        (unsigned long long) from_cblock(residency),
2817                        (unsigned long long) from_cblock(cache->cache_size),
2818                        (unsigned) atomic_read(&cache->stats.read_hit),
2819                        (unsigned) atomic_read(&cache->stats.read_miss),
2820                        (unsigned) atomic_read(&cache->stats.write_hit),
2821                        (unsigned) atomic_read(&cache->stats.write_miss),
2822                        (unsigned) atomic_read(&cache->stats.demotion),
2823                        (unsigned) atomic_read(&cache->stats.promotion),
2824                        (unsigned long long) from_cblock(cache->nr_dirty));
2825
2826                 if (writethrough_mode(&cache->features))
2827                         DMEMIT("1 writethrough ");
2828
2829                 else if (passthrough_mode(&cache->features))
2830                         DMEMIT("1 passthrough ");
2831
2832                 else if (writeback_mode(&cache->features))
2833                         DMEMIT("1 writeback ");
2834
2835                 else {
2836                         DMERR("internal error: unknown io mode: %d", (int) cache->features.io_mode);
2837                         goto err;
2838                 }
2839
2840                 DMEMIT("2 migration_threshold %llu ", (unsigned long long) cache->migration_threshold);
2841
2842                 DMEMIT("%s ", dm_cache_policy_get_name(cache->policy));
2843                 if (sz < maxlen) {
2844                         r = policy_emit_config_values(cache->policy, result + sz, maxlen - sz);
2845                         if (r)
2846                                 DMERR("policy_emit_config_values returned %d", r);
2847                 }
2848
2849                 break;
2850
2851         case STATUSTYPE_TABLE:
2852                 format_dev_t(buf, cache->metadata_dev->bdev->bd_dev);
2853                 DMEMIT("%s ", buf);
2854                 format_dev_t(buf, cache->cache_dev->bdev->bd_dev);
2855                 DMEMIT("%s ", buf);
2856                 format_dev_t(buf, cache->origin_dev->bdev->bd_dev);
2857                 DMEMIT("%s", buf);
2858
2859                 for (i = 0; i < cache->nr_ctr_args - 1; i++)
2860                         DMEMIT(" %s", cache->ctr_args[i]);
2861                 if (cache->nr_ctr_args)
2862                         DMEMIT(" %s", cache->ctr_args[cache->nr_ctr_args - 1]);
2863         }
2864
2865         return;
2866
2867 err:
2868         DMEMIT("Error");
2869 }
2870
2871 /*
2872  * A cache block range can take two forms:
2873  *
2874  * i) A single cblock, eg. '3456'
2875  * ii) A begin and end cblock with dots between, eg. 123-234
2876  */
2877 static int parse_cblock_range(struct cache *cache, const char *str,
2878                               struct cblock_range *result)
2879 {
2880         char dummy;
2881         uint64_t b, e;
2882         int r;
2883
2884         /*
2885          * Try and parse form (ii) first.
2886          */
2887         r = sscanf(str, "%llu-%llu%c", &b, &e, &dummy);
2888         if (r < 0)
2889                 return r;
2890
2891         if (r == 2) {
2892                 result->begin = to_cblock(b);
2893                 result->end = to_cblock(e);
2894                 return 0;
2895         }
2896
2897         /*
2898          * That didn't work, try form (i).
2899          */
2900         r = sscanf(str, "%llu%c", &b, &dummy);
2901         if (r < 0)
2902                 return r;
2903
2904         if (r == 1) {
2905                 result->begin = to_cblock(b);
2906                 result->end = to_cblock(from_cblock(result->begin) + 1u);
2907                 return 0;
2908         }
2909
2910         DMERR("invalid cblock range '%s'", str);
2911         return -EINVAL;
2912 }
2913
2914 static int validate_cblock_range(struct cache *cache, struct cblock_range *range)
2915 {
2916         uint64_t b = from_cblock(range->begin);
2917         uint64_t e = from_cblock(range->end);
2918         uint64_t n = from_cblock(cache->cache_size);
2919
2920         if (b >= n) {
2921                 DMERR("begin cblock out of range: %llu >= %llu", b, n);
2922                 return -EINVAL;
2923         }
2924
2925         if (e > n) {
2926                 DMERR("end cblock out of range: %llu > %llu", e, n);
2927                 return -EINVAL;
2928         }
2929
2930         if (b >= e) {
2931                 DMERR("invalid cblock range: %llu >= %llu", b, e);
2932                 return -EINVAL;
2933         }
2934
2935         return 0;
2936 }
2937
2938 static int request_invalidation(struct cache *cache, struct cblock_range *range)
2939 {
2940         struct invalidation_request req;
2941
2942         INIT_LIST_HEAD(&req.list);
2943         req.cblocks = range;
2944         atomic_set(&req.complete, 0);
2945         req.err = 0;
2946         init_waitqueue_head(&req.result_wait);
2947
2948         spin_lock(&cache->invalidation_lock);
2949         list_add(&req.list, &cache->invalidation_requests);
2950         spin_unlock(&cache->invalidation_lock);
2951         wake_worker(cache);
2952
2953         wait_event(req.result_wait, atomic_read(&req.complete));
2954         return req.err;
2955 }
2956
2957 static int process_invalidate_cblocks_message(struct cache *cache, unsigned count,
2958                                               const char **cblock_ranges)
2959 {
2960         int r = 0;
2961         unsigned i;
2962         struct cblock_range range;
2963
2964         if (!passthrough_mode(&cache->features)) {
2965                 DMERR("cache has to be in passthrough mode for invalidation");
2966                 return -EPERM;
2967         }
2968
2969         for (i = 0; i < count; i++) {
2970                 r = parse_cblock_range(cache, cblock_ranges[i], &range);
2971                 if (r)
2972                         break;
2973
2974                 r = validate_cblock_range(cache, &range);
2975                 if (r)
2976                         break;
2977
2978                 /*
2979                  * Pass begin and end origin blocks to the worker and wake it.
2980                  */
2981                 r = request_invalidation(cache, &range);
2982                 if (r)
2983                         break;
2984         }
2985
2986         return r;
2987 }
2988
2989 /*
2990  * Supports
2991  *      "<key> <value>"
2992  * and
2993  *     "invalidate_cblocks [(<begin>)|(<begin>-<end>)]*
2994  *
2995  * The key migration_threshold is supported by the cache target core.
2996  */
2997 static int cache_message(struct dm_target *ti, unsigned argc, char **argv)
2998 {
2999         struct cache *cache = ti->private;
3000
3001         if (!argc)
3002                 return -EINVAL;
3003
3004         if (!strcasecmp(argv[0], "invalidate_cblocks"))
3005                 return process_invalidate_cblocks_message(cache, argc - 1, (const char **) argv + 1);
3006
3007         if (argc != 2)
3008                 return -EINVAL;
3009
3010         return set_config_value(cache, argv[0], argv[1]);
3011 }
3012
3013 static int cache_iterate_devices(struct dm_target *ti,
3014                                  iterate_devices_callout_fn fn, void *data)
3015 {
3016         int r = 0;
3017         struct cache *cache = ti->private;
3018
3019         r = fn(ti, cache->cache_dev, 0, get_dev_size(cache->cache_dev), data);
3020         if (!r)
3021                 r = fn(ti, cache->origin_dev, 0, ti->len, data);
3022
3023         return r;
3024 }
3025
3026 /*
3027  * We assume I/O is going to the origin (which is the volume
3028  * more likely to have restrictions e.g. by being striped).
3029  * (Looking up the exact location of the data would be expensive
3030  * and could always be out of date by the time the bio is submitted.)
3031  */
3032 static int cache_bvec_merge(struct dm_target *ti,
3033                             struct bvec_merge_data *bvm,
3034                             struct bio_vec *biovec, int max_size)
3035 {
3036         struct cache *cache = ti->private;
3037         struct request_queue *q = bdev_get_queue(cache->origin_dev->bdev);
3038
3039         if (!q->merge_bvec_fn)
3040                 return max_size;
3041
3042         bvm->bi_bdev = cache->origin_dev->bdev;
3043         return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
3044 }
3045
3046 static void set_discard_limits(struct cache *cache, struct queue_limits *limits)
3047 {
3048         /*
3049          * FIXME: these limits may be incompatible with the cache device
3050          */
3051         limits->max_discard_sectors = cache->sectors_per_block;
3052         limits->discard_granularity = cache->sectors_per_block << SECTOR_SHIFT;
3053 }
3054
3055 static void cache_io_hints(struct dm_target *ti, struct queue_limits *limits)
3056 {
3057         struct cache *cache = ti->private;
3058         uint64_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;
3059
3060         /*
3061          * If the system-determined stacked limits are compatible with the
3062          * cache's blocksize (io_opt is a factor) do not override them.
3063          */
3064         if (io_opt_sectors < cache->sectors_per_block ||
3065             do_div(io_opt_sectors, cache->sectors_per_block)) {
3066                 blk_limits_io_min(limits, 0);
3067                 blk_limits_io_opt(limits, cache->sectors_per_block << SECTOR_SHIFT);
3068         }
3069         set_discard_limits(cache, limits);
3070 }
3071
3072 /*----------------------------------------------------------------*/
3073
3074 static struct target_type cache_target = {
3075         .name = "cache",
3076         .version = {1, 4, 0},
3077         .module = THIS_MODULE,
3078         .ctr = cache_ctr,
3079         .dtr = cache_dtr,
3080         .map = cache_map,
3081         .end_io = cache_end_io,
3082         .postsuspend = cache_postsuspend,
3083         .preresume = cache_preresume,
3084         .resume = cache_resume,
3085         .status = cache_status,
3086         .message = cache_message,
3087         .iterate_devices = cache_iterate_devices,
3088         .merge = cache_bvec_merge,
3089         .io_hints = cache_io_hints,
3090 };
3091
3092 static int __init dm_cache_init(void)
3093 {
3094         int r;
3095
3096         r = dm_register_target(&cache_target);
3097         if (r) {
3098                 DMERR("cache target registration failed: %d", r);
3099                 return r;
3100         }
3101
3102         migration_cache = KMEM_CACHE(dm_cache_migration, 0);
3103         if (!migration_cache) {
3104                 dm_unregister_target(&cache_target);
3105                 return -ENOMEM;
3106         }
3107
3108         return 0;
3109 }
3110
3111 static void __exit dm_cache_exit(void)
3112 {
3113         dm_unregister_target(&cache_target);
3114         kmem_cache_destroy(migration_cache);
3115 }
3116
3117 module_init(dm_cache_init);
3118 module_exit(dm_cache_exit);
3119
3120 MODULE_DESCRIPTION(DM_NAME " cache target");
3121 MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
3122 MODULE_LICENSE("GPL");