2 * Copyright (C) 2012 Red Hat. All rights reserved.
4 * This file is released under the GPL.
8 #include "dm-bio-prison.h"
9 #include "dm-bio-record.h"
10 #include "dm-cache-metadata.h"
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>
20 #define DM_MSG_PREFIX "cache"
22 DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(cache_copy_throttle,
23 "A percentage of time allocated for copying to and/or from cache");
25 /*----------------------------------------------------------------*/
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,
38 /*----------------------------------------------------------------*/
40 static size_t bitset_size_in_bytes(unsigned nr_entries)
42 return sizeof(unsigned long) * dm_div_up(nr_entries, BITS_PER_LONG);
45 static unsigned long *alloc_bitset(unsigned nr_entries)
47 size_t s = bitset_size_in_bytes(nr_entries);
51 static void clear_bitset(void *bitset, unsigned nr_entries)
53 size_t s = bitset_size_in_bytes(nr_entries);
57 static void free_bitset(unsigned long *bits)
62 /*----------------------------------------------------------------*/
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.
70 bio_end_io_t *bi_end_io;
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)
77 h->bi_end_io = bio->bi_end_io;
78 h->bi_private = bio->bi_private;
80 bio->bi_end_io = bi_end_io;
81 bio->bi_private = bi_private;
84 static void dm_unhook_bio(struct dm_hook_info *h, struct bio *bio)
86 bio->bi_end_io = h->bi_end_io;
87 bio->bi_private = h->bi_private;
90 * Must bump bi_remaining to allow bio to complete with
93 atomic_inc(&bio->bi_remaining);
96 /*----------------------------------------------------------------*/
98 #define PRISON_CELLS 1024
99 #define MIGRATION_POOL_SIZE 128
100 #define COMMIT_PERIOD HZ
101 #define MIGRATION_COUNT_WINDOW 10
104 * The block size of the device holding cache data must be
105 * between 32KB and 1GB.
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)
111 * FIXME: the cache is read/write for the time being.
113 enum cache_metadata_mode {
114 CM_WRITE, /* metadata may be changed */
115 CM_READ_ONLY, /* metadata may not be changed */
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.
127 * Data is written to both cache and origin. Blocks are never
128 * dirty. Potential performance benfit for reads only.
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.
141 struct cache_features {
142 enum cache_metadata_mode mode;
143 enum cache_io_mode io_mode;
153 atomic_t copies_avoided;
154 atomic_t cache_cell_clash;
155 atomic_t commit_count;
156 atomic_t discard_count;
160 * Defines a range of cblocks, begin to (end - 1) are in the range. end is
161 * the one-past-the-end value.
163 struct cblock_range {
168 struct invalidation_request {
169 struct list_head list;
170 struct cblock_range *cblocks;
175 wait_queue_head_t result_wait;
179 struct dm_target *ti;
180 struct dm_target_callbacks callbacks;
182 struct dm_cache_metadata *cmd;
185 * Metadata is written to this device.
187 struct dm_dev *metadata_dev;
190 * The slower of the two data devices. Typically a spindle.
192 struct dm_dev *origin_dev;
195 * The faster of the two data devices. Typically an SSD.
197 struct dm_dev *cache_dev;
200 * Size of the origin device in _complete_ blocks and native sectors.
202 dm_oblock_t origin_blocks;
203 sector_t origin_sectors;
206 * Size of the cache device in blocks.
208 dm_cblock_t cache_size;
211 * Fields for converting from sectors to blocks.
213 uint32_t sectors_per_block;
214 int sectors_per_block_shift;
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;
227 wait_queue_head_t quiescing_wait;
229 atomic_t quiescing_ack;
232 * cache_size entries, dirty if set
235 unsigned long *dirty_bitset;
238 * origin_blocks entries, discarded if set.
240 dm_oblock_t discard_nr_blocks;
241 unsigned long *discard_bitset;
244 * Rather than reconstructing the table line for the status we just
245 * save it and regurgitate.
247 unsigned nr_ctr_args;
248 const char **ctr_args;
250 struct dm_kcopyd_client *copier;
251 struct workqueue_struct *wq;
252 struct work_struct worker;
254 struct delayed_work waker;
255 unsigned long last_commit_jiffies;
257 struct dm_bio_prison *prison;
258 struct dm_deferred_set *all_io_ds;
260 mempool_t *migration_pool;
261 struct dm_cache_migration *next_migration;
263 struct dm_cache_policy *policy;
264 unsigned policy_nr_args;
266 bool need_tick_bio:1;
269 bool commit_requested:1;
270 bool loaded_mappings:1;
271 bool loaded_discards:1;
274 * Cache features such as write-through.
276 struct cache_features features;
278 struct cache_stats stats;
281 * Invalidation fields.
283 spinlock_t invalidation_lock;
284 struct list_head invalidation_requests;
287 struct per_bio_data {
290 struct dm_deferred_entry *all_io_entry;
291 struct dm_hook_info hook_info;
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.
300 struct dm_bio_details bio_details;
303 struct dm_cache_migration {
304 struct list_head list;
307 unsigned long start_jiffies;
308 dm_oblock_t old_oblock;
309 dm_oblock_t new_oblock;
316 bool requeue_holder:1;
319 struct dm_bio_prison_cell *old_ocell;
320 struct dm_bio_prison_cell *new_ocell;
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).
329 struct dm_cache_migration *mg;
330 struct dm_bio_prison_cell *cell1;
331 struct dm_bio_prison_cell *cell2;
334 static void wake_worker(struct cache *cache)
336 queue_work(cache->wq, &cache->worker);
339 /*----------------------------------------------------------------*/
341 static struct dm_bio_prison_cell *alloc_prison_cell(struct cache *cache)
343 /* FIXME: change to use a local slab. */
344 return dm_bio_prison_alloc_cell(cache->prison, GFP_NOWAIT);
347 static void free_prison_cell(struct cache *cache, struct dm_bio_prison_cell *cell)
349 dm_bio_prison_free_cell(cache->prison, cell);
352 static int prealloc_data_structs(struct cache *cache, struct prealloc *p)
355 p->mg = mempool_alloc(cache->migration_pool, GFP_NOWAIT);
361 p->cell1 = alloc_prison_cell(cache);
367 p->cell2 = alloc_prison_cell(cache);
375 static void prealloc_free_structs(struct cache *cache, struct prealloc *p)
378 free_prison_cell(cache, p->cell2);
381 free_prison_cell(cache, p->cell1);
384 mempool_free(p->mg, cache->migration_pool);
387 static struct dm_cache_migration *prealloc_get_migration(struct prealloc *p)
389 struct dm_cache_migration *mg = p->mg;
398 * You must have a cell within the prealloc struct to return. If not this
399 * function will BUG() rather than returning NULL.
401 static struct dm_bio_prison_cell *prealloc_get_cell(struct prealloc *p)
403 struct dm_bio_prison_cell *r = NULL;
409 } else if (p->cell2) {
419 * You can't have more than two cells in a prealloc struct. BUG() will be
420 * called if you try and overfill.
422 static void prealloc_put_cell(struct prealloc *p, struct dm_bio_prison_cell *cell)
434 /*----------------------------------------------------------------*/
436 static void build_key(dm_oblock_t oblock, struct dm_cell_key *key)
440 key->block = from_oblock(oblock);
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.
448 typedef void (*cell_free_fn)(void *context, struct dm_bio_prison_cell *cell);
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)
456 struct dm_cell_key key;
458 build_key(oblock, &key);
459 r = dm_bio_detain(cache->prison, &key, bio, cell_prealloc, cell_result);
461 free_fn(free_context, cell_prealloc);
466 static int get_cell(struct cache *cache,
468 struct prealloc *structs,
469 struct dm_bio_prison_cell **cell_result)
472 struct dm_cell_key key;
473 struct dm_bio_prison_cell *cell_prealloc;
475 cell_prealloc = prealloc_get_cell(structs);
477 build_key(oblock, &key);
478 r = dm_get_cell(cache->prison, &key, cell_prealloc, cell_result);
480 prealloc_put_cell(structs, cell_prealloc);
485 /*----------------------------------------------------------------*/
487 static bool is_dirty(struct cache *cache, dm_cblock_t b)
489 return test_bit(from_cblock(b), cache->dirty_bitset);
492 static void set_dirty(struct cache *cache, dm_oblock_t oblock, dm_cblock_t cblock)
494 if (!test_and_set_bit(from_cblock(cblock), cache->dirty_bitset)) {
495 atomic_inc(&cache->nr_dirty);
496 policy_set_dirty(cache->policy, oblock);
500 static void clear_dirty(struct cache *cache, dm_oblock_t oblock, dm_cblock_t cblock)
502 if (test_and_clear_bit(from_cblock(cblock), cache->dirty_bitset)) {
503 policy_clear_dirty(cache->policy, oblock);
504 if (atomic_dec_return(&cache->nr_dirty) == 0)
505 dm_table_event(cache->ti->table);
509 /*----------------------------------------------------------------*/
511 static bool block_size_is_power_of_two(struct cache *cache)
513 return cache->sectors_per_block_shift >= 0;
516 /* gcc on ARM generates spurious references to __udivdi3 and __umoddi3 */
517 #if defined(CONFIG_ARM) && __GNUC__ == 4 && __GNUC_MINOR__ <= 6
520 static dm_block_t block_div(dm_block_t b, uint32_t n)
527 static void set_discard(struct cache *cache, dm_oblock_t b)
531 atomic_inc(&cache->stats.discard_count);
533 spin_lock_irqsave(&cache->lock, flags);
534 set_bit(from_oblock(b), cache->discard_bitset);
535 spin_unlock_irqrestore(&cache->lock, flags);
538 static void clear_discard(struct cache *cache, dm_oblock_t b)
542 spin_lock_irqsave(&cache->lock, flags);
543 clear_bit(from_oblock(b), cache->discard_bitset);
544 spin_unlock_irqrestore(&cache->lock, flags);
547 static bool is_discarded(struct cache *cache, dm_oblock_t b)
552 spin_lock_irqsave(&cache->lock, flags);
553 r = test_bit(from_oblock(b), cache->discard_bitset);
554 spin_unlock_irqrestore(&cache->lock, flags);
559 static bool is_discarded_oblock(struct cache *cache, dm_oblock_t b)
564 spin_lock_irqsave(&cache->lock, flags);
565 r = test_bit(from_oblock(b), cache->discard_bitset);
566 spin_unlock_irqrestore(&cache->lock, flags);
571 /*----------------------------------------------------------------*/
573 static void load_stats(struct cache *cache)
575 struct dm_cache_statistics stats;
577 dm_cache_metadata_get_stats(cache->cmd, &stats);
578 atomic_set(&cache->stats.read_hit, stats.read_hits);
579 atomic_set(&cache->stats.read_miss, stats.read_misses);
580 atomic_set(&cache->stats.write_hit, stats.write_hits);
581 atomic_set(&cache->stats.write_miss, stats.write_misses);
584 static void save_stats(struct cache *cache)
586 struct dm_cache_statistics stats;
588 stats.read_hits = atomic_read(&cache->stats.read_hit);
589 stats.read_misses = atomic_read(&cache->stats.read_miss);
590 stats.write_hits = atomic_read(&cache->stats.write_hit);
591 stats.write_misses = atomic_read(&cache->stats.write_miss);
593 dm_cache_metadata_set_stats(cache->cmd, &stats);
596 /*----------------------------------------------------------------
598 *--------------------------------------------------------------*/
601 * If using writeback, leave out struct per_bio_data's writethrough fields.
603 #define PB_DATA_SIZE_WB (offsetof(struct per_bio_data, cache))
604 #define PB_DATA_SIZE_WT (sizeof(struct per_bio_data))
606 static bool writethrough_mode(struct cache_features *f)
608 return f->io_mode == CM_IO_WRITETHROUGH;
611 static bool writeback_mode(struct cache_features *f)
613 return f->io_mode == CM_IO_WRITEBACK;
616 static bool passthrough_mode(struct cache_features *f)
618 return f->io_mode == CM_IO_PASSTHROUGH;
621 static size_t get_per_bio_data_size(struct cache *cache)
623 return writethrough_mode(&cache->features) ? PB_DATA_SIZE_WT : PB_DATA_SIZE_WB;
626 static struct per_bio_data *get_per_bio_data(struct bio *bio, size_t data_size)
628 struct per_bio_data *pb = dm_per_bio_data(bio, data_size);
633 static struct per_bio_data *init_per_bio_data(struct bio *bio, size_t data_size)
635 struct per_bio_data *pb = get_per_bio_data(bio, data_size);
638 pb->req_nr = dm_bio_get_target_bio_nr(bio);
639 pb->all_io_entry = NULL;
644 /*----------------------------------------------------------------
646 *--------------------------------------------------------------*/
647 static void remap_to_origin(struct cache *cache, struct bio *bio)
649 bio->bi_bdev = cache->origin_dev->bdev;
652 static void remap_to_cache(struct cache *cache, struct bio *bio,
655 sector_t bi_sector = bio->bi_iter.bi_sector;
656 sector_t block = from_cblock(cblock);
658 bio->bi_bdev = cache->cache_dev->bdev;
659 if (!block_size_is_power_of_two(cache))
660 bio->bi_iter.bi_sector =
661 (block * cache->sectors_per_block) +
662 sector_div(bi_sector, cache->sectors_per_block);
664 bio->bi_iter.bi_sector =
665 (block << cache->sectors_per_block_shift) |
666 (bi_sector & (cache->sectors_per_block - 1));
669 static void check_if_tick_bio_needed(struct cache *cache, struct bio *bio)
672 size_t pb_data_size = get_per_bio_data_size(cache);
673 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
675 spin_lock_irqsave(&cache->lock, flags);
676 if (cache->need_tick_bio &&
677 !(bio->bi_rw & (REQ_FUA | REQ_FLUSH | REQ_DISCARD))) {
679 cache->need_tick_bio = false;
681 spin_unlock_irqrestore(&cache->lock, flags);
684 static void remap_to_origin_clear_discard(struct cache *cache, struct bio *bio,
687 check_if_tick_bio_needed(cache, bio);
688 remap_to_origin(cache, bio);
689 if (bio_data_dir(bio) == WRITE)
690 clear_discard(cache, oblock);
693 static void remap_to_cache_dirty(struct cache *cache, struct bio *bio,
694 dm_oblock_t oblock, dm_cblock_t cblock)
696 check_if_tick_bio_needed(cache, bio);
697 remap_to_cache(cache, bio, cblock);
698 if (bio_data_dir(bio) == WRITE) {
699 set_dirty(cache, oblock, cblock);
700 clear_discard(cache, oblock);
704 static dm_oblock_t get_bio_block(struct cache *cache, struct bio *bio)
706 sector_t block_nr = bio->bi_iter.bi_sector;
708 if (!block_size_is_power_of_two(cache))
709 (void) sector_div(block_nr, cache->sectors_per_block);
711 block_nr >>= cache->sectors_per_block_shift;
713 return to_oblock(block_nr);
716 static int bio_triggers_commit(struct cache *cache, struct bio *bio)
718 return bio->bi_rw & (REQ_FLUSH | REQ_FUA);
722 * You must increment the deferred set whilst the prison cell is held. To
723 * encourage this, we ask for 'cell' to be passed in.
725 static void inc_ds(struct cache *cache, struct bio *bio,
726 struct dm_bio_prison_cell *cell)
728 size_t pb_data_size = get_per_bio_data_size(cache);
729 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
732 BUG_ON(pb->all_io_entry);
734 pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
737 static void issue(struct cache *cache, struct bio *bio)
741 if (!bio_triggers_commit(cache, bio)) {
742 generic_make_request(bio);
747 * Batch together any bios that trigger commits and then issue a
748 * single commit for them in do_worker().
750 spin_lock_irqsave(&cache->lock, flags);
751 cache->commit_requested = true;
752 bio_list_add(&cache->deferred_flush_bios, bio);
753 spin_unlock_irqrestore(&cache->lock, flags);
756 static void inc_and_issue(struct cache *cache, struct bio *bio, struct dm_bio_prison_cell *cell)
758 inc_ds(cache, bio, cell);
762 static void defer_writethrough_bio(struct cache *cache, struct bio *bio)
766 spin_lock_irqsave(&cache->lock, flags);
767 bio_list_add(&cache->deferred_writethrough_bios, bio);
768 spin_unlock_irqrestore(&cache->lock, flags);
773 static void writethrough_endio(struct bio *bio, int err)
775 struct per_bio_data *pb = get_per_bio_data(bio, PB_DATA_SIZE_WT);
777 dm_unhook_bio(&pb->hook_info, bio);
784 dm_bio_restore(&pb->bio_details, bio);
785 remap_to_cache(pb->cache, bio, pb->cblock);
788 * We can't issue this bio directly, since we're in interrupt
789 * context. So it gets put on a bio list for processing by the
792 defer_writethrough_bio(pb->cache, bio);
796 * When running in writethrough mode we need to send writes to clean blocks
797 * to both the cache and origin devices. In future we'd like to clone the
798 * bio and send them in parallel, but for now we're doing them in
799 * series as this is easier.
801 static void remap_to_origin_then_cache(struct cache *cache, struct bio *bio,
802 dm_oblock_t oblock, dm_cblock_t cblock)
804 struct per_bio_data *pb = get_per_bio_data(bio, PB_DATA_SIZE_WT);
808 dm_hook_bio(&pb->hook_info, bio, writethrough_endio, NULL);
809 dm_bio_record(&pb->bio_details, bio);
811 remap_to_origin_clear_discard(pb->cache, bio, oblock);
814 /*----------------------------------------------------------------
815 * Migration processing
817 * Migration covers moving data from the origin device to the cache, or
819 *--------------------------------------------------------------*/
820 static void free_migration(struct dm_cache_migration *mg)
822 mempool_free(mg, mg->cache->migration_pool);
825 static void inc_nr_migrations(struct cache *cache)
827 atomic_inc(&cache->nr_migrations);
830 static void dec_nr_migrations(struct cache *cache)
832 atomic_dec(&cache->nr_migrations);
835 * Wake the worker in case we're suspending the target.
837 wake_up(&cache->migration_wait);
840 static void __cell_defer(struct cache *cache, struct dm_bio_prison_cell *cell,
843 (holder ? dm_cell_release : dm_cell_release_no_holder)
844 (cache->prison, cell, &cache->deferred_bios);
845 free_prison_cell(cache, cell);
848 static void cell_defer(struct cache *cache, struct dm_bio_prison_cell *cell,
853 spin_lock_irqsave(&cache->lock, flags);
854 __cell_defer(cache, cell, holder);
855 spin_unlock_irqrestore(&cache->lock, flags);
860 static void cleanup_migration(struct dm_cache_migration *mg)
862 struct cache *cache = mg->cache;
864 dec_nr_migrations(cache);
867 static void migration_failure(struct dm_cache_migration *mg)
869 struct cache *cache = mg->cache;
872 DMWARN_LIMIT("writeback failed; couldn't copy block");
873 set_dirty(cache, mg->old_oblock, mg->cblock);
874 cell_defer(cache, mg->old_ocell, false);
876 } else if (mg->demote) {
877 DMWARN_LIMIT("demotion failed; couldn't copy block");
878 policy_force_mapping(cache->policy, mg->new_oblock, mg->old_oblock);
880 cell_defer(cache, mg->old_ocell, mg->promote ? false : true);
882 cell_defer(cache, mg->new_ocell, true);
884 DMWARN_LIMIT("promotion failed; couldn't copy block");
885 policy_remove_mapping(cache->policy, mg->new_oblock);
886 cell_defer(cache, mg->new_ocell, true);
889 cleanup_migration(mg);
892 static void migration_success_pre_commit(struct dm_cache_migration *mg)
895 struct cache *cache = mg->cache;
898 clear_dirty(cache, mg->old_oblock, mg->cblock);
899 cell_defer(cache, mg->old_ocell, false);
900 cleanup_migration(mg);
903 } else if (mg->demote) {
904 if (dm_cache_remove_mapping(cache->cmd, mg->cblock)) {
905 DMWARN_LIMIT("demotion failed; couldn't update on disk metadata");
906 policy_force_mapping(cache->policy, mg->new_oblock,
909 cell_defer(cache, mg->new_ocell, true);
910 cleanup_migration(mg);
914 if (dm_cache_insert_mapping(cache->cmd, mg->cblock, mg->new_oblock)) {
915 DMWARN_LIMIT("promotion failed; couldn't update on disk metadata");
916 policy_remove_mapping(cache->policy, mg->new_oblock);
917 cleanup_migration(mg);
922 spin_lock_irqsave(&cache->lock, flags);
923 list_add_tail(&mg->list, &cache->need_commit_migrations);
924 cache->commit_requested = true;
925 spin_unlock_irqrestore(&cache->lock, flags);
928 static void migration_success_post_commit(struct dm_cache_migration *mg)
931 struct cache *cache = mg->cache;
934 DMWARN("writeback unexpectedly triggered commit");
937 } else if (mg->demote) {
938 cell_defer(cache, mg->old_ocell, mg->promote ? false : true);
943 spin_lock_irqsave(&cache->lock, flags);
944 list_add_tail(&mg->list, &cache->quiesced_migrations);
945 spin_unlock_irqrestore(&cache->lock, flags);
949 policy_remove_mapping(cache->policy, mg->old_oblock);
950 cleanup_migration(mg);
954 clear_dirty(cache, mg->new_oblock, mg->cblock);
955 if (mg->requeue_holder)
956 cell_defer(cache, mg->new_ocell, true);
958 bio_endio(mg->new_ocell->holder, 0);
959 cell_defer(cache, mg->new_ocell, false);
961 cleanup_migration(mg);
965 static void copy_complete(int read_err, unsigned long write_err, void *context)
968 struct dm_cache_migration *mg = (struct dm_cache_migration *) context;
969 struct cache *cache = mg->cache;
971 if (read_err || write_err)
974 spin_lock_irqsave(&cache->lock, flags);
975 list_add_tail(&mg->list, &cache->completed_migrations);
976 spin_unlock_irqrestore(&cache->lock, flags);
981 static void issue_copy_real(struct dm_cache_migration *mg)
984 struct dm_io_region o_region, c_region;
985 struct cache *cache = mg->cache;
986 sector_t cblock = from_cblock(mg->cblock);
988 o_region.bdev = cache->origin_dev->bdev;
989 o_region.count = cache->sectors_per_block;
991 c_region.bdev = cache->cache_dev->bdev;
992 c_region.sector = cblock * cache->sectors_per_block;
993 c_region.count = cache->sectors_per_block;
995 if (mg->writeback || mg->demote) {
997 o_region.sector = from_oblock(mg->old_oblock) * cache->sectors_per_block;
998 r = dm_kcopyd_copy(cache->copier, &c_region, 1, &o_region, 0, copy_complete, mg);
1001 o_region.sector = from_oblock(mg->new_oblock) * cache->sectors_per_block;
1002 r = dm_kcopyd_copy(cache->copier, &o_region, 1, &c_region, 0, copy_complete, mg);
1006 DMERR_LIMIT("issuing migration failed");
1007 migration_failure(mg);
1011 static void overwrite_endio(struct bio *bio, int err)
1013 struct dm_cache_migration *mg = bio->bi_private;
1014 struct cache *cache = mg->cache;
1015 size_t pb_data_size = get_per_bio_data_size(cache);
1016 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
1017 unsigned long flags;
1019 dm_unhook_bio(&pb->hook_info, bio);
1024 mg->requeue_holder = false;
1026 spin_lock_irqsave(&cache->lock, flags);
1027 list_add_tail(&mg->list, &cache->completed_migrations);
1028 spin_unlock_irqrestore(&cache->lock, flags);
1033 static void issue_overwrite(struct dm_cache_migration *mg, struct bio *bio)
1035 size_t pb_data_size = get_per_bio_data_size(mg->cache);
1036 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
1038 dm_hook_bio(&pb->hook_info, bio, overwrite_endio, mg);
1039 remap_to_cache_dirty(mg->cache, bio, mg->new_oblock, mg->cblock);
1042 * No need to inc_ds() here, since the cell will be held for the
1043 * duration of the io.
1045 generic_make_request(bio);
1048 static bool bio_writes_complete_block(struct cache *cache, struct bio *bio)
1050 return (bio_data_dir(bio) == WRITE) &&
1051 (bio->bi_iter.bi_size == (cache->sectors_per_block << SECTOR_SHIFT));
1054 static void avoid_copy(struct dm_cache_migration *mg)
1056 atomic_inc(&mg->cache->stats.copies_avoided);
1057 migration_success_pre_commit(mg);
1060 static void issue_copy(struct dm_cache_migration *mg)
1063 struct cache *cache = mg->cache;
1065 if (mg->writeback || mg->demote)
1066 avoid = !is_dirty(cache, mg->cblock) ||
1067 is_discarded_oblock(cache, mg->old_oblock);
1069 struct bio *bio = mg->new_ocell->holder;
1071 avoid = is_discarded_oblock(cache, mg->new_oblock);
1073 if (!avoid && bio_writes_complete_block(cache, bio)) {
1074 issue_overwrite(mg, bio);
1079 avoid ? avoid_copy(mg) : issue_copy_real(mg);
1082 static void complete_migration(struct dm_cache_migration *mg)
1085 migration_failure(mg);
1087 migration_success_pre_commit(mg);
1090 static void process_migrations(struct cache *cache, struct list_head *head,
1091 void (*fn)(struct dm_cache_migration *))
1093 unsigned long flags;
1094 struct list_head list;
1095 struct dm_cache_migration *mg, *tmp;
1097 INIT_LIST_HEAD(&list);
1098 spin_lock_irqsave(&cache->lock, flags);
1099 list_splice_init(head, &list);
1100 spin_unlock_irqrestore(&cache->lock, flags);
1102 list_for_each_entry_safe(mg, tmp, &list, list)
1106 static void __queue_quiesced_migration(struct dm_cache_migration *mg)
1108 list_add_tail(&mg->list, &mg->cache->quiesced_migrations);
1111 static void queue_quiesced_migration(struct dm_cache_migration *mg)
1113 unsigned long flags;
1114 struct cache *cache = mg->cache;
1116 spin_lock_irqsave(&cache->lock, flags);
1117 __queue_quiesced_migration(mg);
1118 spin_unlock_irqrestore(&cache->lock, flags);
1123 static void queue_quiesced_migrations(struct cache *cache, struct list_head *work)
1125 unsigned long flags;
1126 struct dm_cache_migration *mg, *tmp;
1128 spin_lock_irqsave(&cache->lock, flags);
1129 list_for_each_entry_safe(mg, tmp, work, list)
1130 __queue_quiesced_migration(mg);
1131 spin_unlock_irqrestore(&cache->lock, flags);
1136 static void check_for_quiesced_migrations(struct cache *cache,
1137 struct per_bio_data *pb)
1139 struct list_head work;
1141 if (!pb->all_io_entry)
1144 INIT_LIST_HEAD(&work);
1145 dm_deferred_entry_dec(pb->all_io_entry, &work);
1147 if (!list_empty(&work))
1148 queue_quiesced_migrations(cache, &work);
1151 static void quiesce_migration(struct dm_cache_migration *mg)
1153 if (!dm_deferred_set_add_work(mg->cache->all_io_ds, &mg->list))
1154 queue_quiesced_migration(mg);
1157 static void promote(struct cache *cache, struct prealloc *structs,
1158 dm_oblock_t oblock, dm_cblock_t cblock,
1159 struct dm_bio_prison_cell *cell)
1161 struct dm_cache_migration *mg = prealloc_get_migration(structs);
1164 mg->writeback = false;
1167 mg->requeue_holder = true;
1168 mg->invalidate = false;
1170 mg->new_oblock = oblock;
1171 mg->cblock = cblock;
1172 mg->old_ocell = NULL;
1173 mg->new_ocell = cell;
1174 mg->start_jiffies = jiffies;
1176 inc_nr_migrations(cache);
1177 quiesce_migration(mg);
1180 static void writeback(struct cache *cache, struct prealloc *structs,
1181 dm_oblock_t oblock, dm_cblock_t cblock,
1182 struct dm_bio_prison_cell *cell)
1184 struct dm_cache_migration *mg = prealloc_get_migration(structs);
1187 mg->writeback = true;
1189 mg->promote = false;
1190 mg->requeue_holder = true;
1191 mg->invalidate = false;
1193 mg->old_oblock = oblock;
1194 mg->cblock = cblock;
1195 mg->old_ocell = cell;
1196 mg->new_ocell = NULL;
1197 mg->start_jiffies = jiffies;
1199 inc_nr_migrations(cache);
1200 quiesce_migration(mg);
1203 static void demote_then_promote(struct cache *cache, struct prealloc *structs,
1204 dm_oblock_t old_oblock, dm_oblock_t new_oblock,
1206 struct dm_bio_prison_cell *old_ocell,
1207 struct dm_bio_prison_cell *new_ocell)
1209 struct dm_cache_migration *mg = prealloc_get_migration(structs);
1212 mg->writeback = false;
1215 mg->requeue_holder = true;
1216 mg->invalidate = false;
1218 mg->old_oblock = old_oblock;
1219 mg->new_oblock = new_oblock;
1220 mg->cblock = cblock;
1221 mg->old_ocell = old_ocell;
1222 mg->new_ocell = new_ocell;
1223 mg->start_jiffies = jiffies;
1225 inc_nr_migrations(cache);
1226 quiesce_migration(mg);
1230 * Invalidate a cache entry. No writeback occurs; any changes in the cache
1231 * block are thrown away.
1233 static void invalidate(struct cache *cache, struct prealloc *structs,
1234 dm_oblock_t oblock, dm_cblock_t cblock,
1235 struct dm_bio_prison_cell *cell)
1237 struct dm_cache_migration *mg = prealloc_get_migration(structs);
1240 mg->writeback = false;
1242 mg->promote = false;
1243 mg->requeue_holder = true;
1244 mg->invalidate = true;
1246 mg->old_oblock = oblock;
1247 mg->cblock = cblock;
1248 mg->old_ocell = cell;
1249 mg->new_ocell = NULL;
1250 mg->start_jiffies = jiffies;
1252 inc_nr_migrations(cache);
1253 quiesce_migration(mg);
1256 /*----------------------------------------------------------------
1258 *--------------------------------------------------------------*/
1259 static void defer_bio(struct cache *cache, struct bio *bio)
1261 unsigned long flags;
1263 spin_lock_irqsave(&cache->lock, flags);
1264 bio_list_add(&cache->deferred_bios, bio);
1265 spin_unlock_irqrestore(&cache->lock, flags);
1270 static void process_flush_bio(struct cache *cache, struct bio *bio)
1272 size_t pb_data_size = get_per_bio_data_size(cache);
1273 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
1275 BUG_ON(bio->bi_iter.bi_size);
1277 remap_to_origin(cache, bio);
1279 remap_to_cache(cache, bio, 0);
1282 * REQ_FLUSH is not directed at any particular block so we don't
1283 * need to inc_ds(). REQ_FUA's are split into a write + REQ_FLUSH
1290 * People generally discard large parts of a device, eg, the whole device
1291 * when formatting. Splitting these large discards up into cache block
1292 * sized ios and then quiescing (always neccessary for discard) takes too
1295 * We keep it simple, and allow any size of discard to come in, and just
1296 * mark off blocks on the discard bitset. No passdown occurs!
1298 * To implement passdown we need to change the bio_prison such that a cell
1299 * can have a key that spans many blocks.
1301 static void process_discard_bio(struct cache *cache, struct bio *bio)
1303 dm_block_t start_block = dm_sector_div_up(bio->bi_iter.bi_sector,
1304 cache->sectors_per_block);
1305 dm_block_t end_block = bio_end_sector(bio);
1308 end_block = block_div(end_block, cache->sectors_per_block);
1310 for (b = start_block; b < end_block; b++)
1311 set_discard(cache, to_oblock(b));
1316 static bool spare_migration_bandwidth(struct cache *cache)
1318 sector_t current_volume = (atomic_read(&cache->nr_migrations) + 1) *
1319 cache->sectors_per_block;
1320 return current_volume < cache->migration_threshold;
1323 static void inc_hit_counter(struct cache *cache, struct bio *bio)
1325 atomic_inc(bio_data_dir(bio) == READ ?
1326 &cache->stats.read_hit : &cache->stats.write_hit);
1329 static void inc_miss_counter(struct cache *cache, struct bio *bio)
1331 atomic_inc(bio_data_dir(bio) == READ ?
1332 &cache->stats.read_miss : &cache->stats.write_miss);
1335 static void process_bio(struct cache *cache, struct prealloc *structs,
1339 bool release_cell = true;
1340 dm_oblock_t block = get_bio_block(cache, bio);
1341 struct dm_bio_prison_cell *cell_prealloc, *old_ocell, *new_ocell;
1342 struct policy_result lookup_result;
1343 bool discarded_block = is_discarded_oblock(cache, block);
1344 bool passthrough = passthrough_mode(&cache->features);
1345 bool can_migrate = !passthrough && (discarded_block || spare_migration_bandwidth(cache));
1348 * Check to see if that block is currently migrating.
1350 cell_prealloc = prealloc_get_cell(structs);
1351 r = bio_detain(cache, block, bio, cell_prealloc,
1352 (cell_free_fn) prealloc_put_cell,
1353 structs, &new_ocell);
1357 r = policy_map(cache->policy, block, true, can_migrate, discarded_block,
1358 bio, &lookup_result);
1360 if (r == -EWOULDBLOCK)
1361 /* migration has been denied */
1362 lookup_result.op = POLICY_MISS;
1364 switch (lookup_result.op) {
1367 inc_miss_counter(cache, bio);
1370 * Passthrough always maps to the origin,
1371 * invalidating any cache blocks that are written
1375 if (bio_data_dir(bio) == WRITE) {
1376 atomic_inc(&cache->stats.demotion);
1377 invalidate(cache, structs, block, lookup_result.cblock, new_ocell);
1378 release_cell = false;
1381 /* FIXME: factor out issue_origin() */
1382 remap_to_origin_clear_discard(cache, bio, block);
1383 inc_and_issue(cache, bio, new_ocell);
1386 inc_hit_counter(cache, bio);
1388 if (bio_data_dir(bio) == WRITE &&
1389 writethrough_mode(&cache->features) &&
1390 !is_dirty(cache, lookup_result.cblock)) {
1391 remap_to_origin_then_cache(cache, bio, block, lookup_result.cblock);
1392 inc_and_issue(cache, bio, new_ocell);
1395 remap_to_cache_dirty(cache, bio, block, lookup_result.cblock);
1396 inc_and_issue(cache, bio, new_ocell);
1403 inc_miss_counter(cache, bio);
1404 remap_to_origin_clear_discard(cache, bio, block);
1405 inc_and_issue(cache, bio, new_ocell);
1409 atomic_inc(&cache->stats.promotion);
1410 promote(cache, structs, block, lookup_result.cblock, new_ocell);
1411 release_cell = false;
1414 case POLICY_REPLACE:
1415 cell_prealloc = prealloc_get_cell(structs);
1416 r = bio_detain(cache, lookup_result.old_oblock, bio, cell_prealloc,
1417 (cell_free_fn) prealloc_put_cell,
1418 structs, &old_ocell);
1421 * We have to be careful to avoid lock inversion of
1422 * the cells. So we back off, and wait for the
1423 * old_ocell to become free.
1425 policy_force_mapping(cache->policy, block,
1426 lookup_result.old_oblock);
1427 atomic_inc(&cache->stats.cache_cell_clash);
1430 atomic_inc(&cache->stats.demotion);
1431 atomic_inc(&cache->stats.promotion);
1433 demote_then_promote(cache, structs, lookup_result.old_oblock,
1434 block, lookup_result.cblock,
1435 old_ocell, new_ocell);
1436 release_cell = false;
1440 DMERR_LIMIT("%s: erroring bio, unknown policy op: %u", __func__,
1441 (unsigned) lookup_result.op);
1446 cell_defer(cache, new_ocell, false);
1449 static int need_commit_due_to_time(struct cache *cache)
1451 return jiffies < cache->last_commit_jiffies ||
1452 jiffies > cache->last_commit_jiffies + COMMIT_PERIOD;
1455 static int commit_if_needed(struct cache *cache)
1459 if ((cache->commit_requested || need_commit_due_to_time(cache)) &&
1460 dm_cache_changed_this_transaction(cache->cmd)) {
1461 atomic_inc(&cache->stats.commit_count);
1462 cache->commit_requested = false;
1463 r = dm_cache_commit(cache->cmd, false);
1464 cache->last_commit_jiffies = jiffies;
1470 static void process_deferred_bios(struct cache *cache)
1472 unsigned long flags;
1473 struct bio_list bios;
1475 struct prealloc structs;
1477 memset(&structs, 0, sizeof(structs));
1478 bio_list_init(&bios);
1480 spin_lock_irqsave(&cache->lock, flags);
1481 bio_list_merge(&bios, &cache->deferred_bios);
1482 bio_list_init(&cache->deferred_bios);
1483 spin_unlock_irqrestore(&cache->lock, flags);
1485 while (!bio_list_empty(&bios)) {
1487 * If we've got no free migration structs, and processing
1488 * this bio might require one, we pause until there are some
1489 * prepared mappings to process.
1491 if (prealloc_data_structs(cache, &structs)) {
1492 spin_lock_irqsave(&cache->lock, flags);
1493 bio_list_merge(&cache->deferred_bios, &bios);
1494 spin_unlock_irqrestore(&cache->lock, flags);
1498 bio = bio_list_pop(&bios);
1500 if (bio->bi_rw & REQ_FLUSH)
1501 process_flush_bio(cache, bio);
1502 else if (bio->bi_rw & REQ_DISCARD)
1503 process_discard_bio(cache, bio);
1505 process_bio(cache, &structs, bio);
1508 prealloc_free_structs(cache, &structs);
1511 static void process_deferred_flush_bios(struct cache *cache, bool submit_bios)
1513 unsigned long flags;
1514 struct bio_list bios;
1517 bio_list_init(&bios);
1519 spin_lock_irqsave(&cache->lock, flags);
1520 bio_list_merge(&bios, &cache->deferred_flush_bios);
1521 bio_list_init(&cache->deferred_flush_bios);
1522 spin_unlock_irqrestore(&cache->lock, flags);
1525 * These bios have already been through inc_ds()
1527 while ((bio = bio_list_pop(&bios)))
1528 submit_bios ? generic_make_request(bio) : bio_io_error(bio);
1531 static void process_deferred_writethrough_bios(struct cache *cache)
1533 unsigned long flags;
1534 struct bio_list bios;
1537 bio_list_init(&bios);
1539 spin_lock_irqsave(&cache->lock, flags);
1540 bio_list_merge(&bios, &cache->deferred_writethrough_bios);
1541 bio_list_init(&cache->deferred_writethrough_bios);
1542 spin_unlock_irqrestore(&cache->lock, flags);
1545 * These bios have already been through inc_ds()
1547 while ((bio = bio_list_pop(&bios)))
1548 generic_make_request(bio);
1551 static void writeback_some_dirty_blocks(struct cache *cache)
1556 struct prealloc structs;
1557 struct dm_bio_prison_cell *old_ocell;
1559 memset(&structs, 0, sizeof(structs));
1561 while (spare_migration_bandwidth(cache)) {
1562 if (prealloc_data_structs(cache, &structs))
1565 r = policy_writeback_work(cache->policy, &oblock, &cblock);
1569 r = get_cell(cache, oblock, &structs, &old_ocell);
1571 policy_set_dirty(cache->policy, oblock);
1575 writeback(cache, &structs, oblock, cblock, old_ocell);
1578 prealloc_free_structs(cache, &structs);
1581 /*----------------------------------------------------------------
1583 * Dropping something from the cache *without* writing back.
1584 *--------------------------------------------------------------*/
1586 static void process_invalidation_request(struct cache *cache, struct invalidation_request *req)
1589 uint64_t begin = from_cblock(req->cblocks->begin);
1590 uint64_t end = from_cblock(req->cblocks->end);
1592 while (begin != end) {
1593 r = policy_remove_cblock(cache->policy, to_cblock(begin));
1595 r = dm_cache_remove_mapping(cache->cmd, to_cblock(begin));
1599 } else if (r == -ENODATA) {
1600 /* harmless, already unmapped */
1604 DMERR("policy_remove_cblock failed");
1611 cache->commit_requested = true;
1614 atomic_set(&req->complete, 1);
1616 wake_up(&req->result_wait);
1619 static void process_invalidation_requests(struct cache *cache)
1621 struct list_head list;
1622 struct invalidation_request *req, *tmp;
1624 INIT_LIST_HEAD(&list);
1625 spin_lock(&cache->invalidation_lock);
1626 list_splice_init(&cache->invalidation_requests, &list);
1627 spin_unlock(&cache->invalidation_lock);
1629 list_for_each_entry_safe (req, tmp, &list, list)
1630 process_invalidation_request(cache, req);
1633 /*----------------------------------------------------------------
1635 *--------------------------------------------------------------*/
1636 static bool is_quiescing(struct cache *cache)
1638 return atomic_read(&cache->quiescing);
1641 static void ack_quiescing(struct cache *cache)
1643 if (is_quiescing(cache)) {
1644 atomic_inc(&cache->quiescing_ack);
1645 wake_up(&cache->quiescing_wait);
1649 static void wait_for_quiescing_ack(struct cache *cache)
1651 wait_event(cache->quiescing_wait, atomic_read(&cache->quiescing_ack));
1654 static void start_quiescing(struct cache *cache)
1656 atomic_inc(&cache->quiescing);
1657 wait_for_quiescing_ack(cache);
1660 static void stop_quiescing(struct cache *cache)
1662 atomic_set(&cache->quiescing, 0);
1663 atomic_set(&cache->quiescing_ack, 0);
1666 static void wait_for_migrations(struct cache *cache)
1668 wait_event(cache->migration_wait, !atomic_read(&cache->nr_migrations));
1671 static void stop_worker(struct cache *cache)
1673 cancel_delayed_work(&cache->waker);
1674 flush_workqueue(cache->wq);
1677 static void requeue_deferred_io(struct cache *cache)
1680 struct bio_list bios;
1682 bio_list_init(&bios);
1683 bio_list_merge(&bios, &cache->deferred_bios);
1684 bio_list_init(&cache->deferred_bios);
1686 while ((bio = bio_list_pop(&bios)))
1687 bio_endio(bio, DM_ENDIO_REQUEUE);
1690 static int more_work(struct cache *cache)
1692 if (is_quiescing(cache))
1693 return !list_empty(&cache->quiesced_migrations) ||
1694 !list_empty(&cache->completed_migrations) ||
1695 !list_empty(&cache->need_commit_migrations);
1697 return !bio_list_empty(&cache->deferred_bios) ||
1698 !bio_list_empty(&cache->deferred_flush_bios) ||
1699 !bio_list_empty(&cache->deferred_writethrough_bios) ||
1700 !list_empty(&cache->quiesced_migrations) ||
1701 !list_empty(&cache->completed_migrations) ||
1702 !list_empty(&cache->need_commit_migrations) ||
1706 static void do_worker(struct work_struct *ws)
1708 struct cache *cache = container_of(ws, struct cache, worker);
1711 if (!is_quiescing(cache)) {
1712 writeback_some_dirty_blocks(cache);
1713 process_deferred_writethrough_bios(cache);
1714 process_deferred_bios(cache);
1715 process_invalidation_requests(cache);
1718 process_migrations(cache, &cache->quiesced_migrations, issue_copy);
1719 process_migrations(cache, &cache->completed_migrations, complete_migration);
1721 if (commit_if_needed(cache)) {
1722 process_deferred_flush_bios(cache, false);
1723 process_migrations(cache, &cache->need_commit_migrations, migration_failure);
1726 * FIXME: rollback metadata or just go into a
1727 * failure mode and error everything
1730 process_deferred_flush_bios(cache, true);
1731 process_migrations(cache, &cache->need_commit_migrations,
1732 migration_success_post_commit);
1735 ack_quiescing(cache);
1737 } while (more_work(cache));
1741 * We want to commit periodically so that not too much
1742 * unwritten metadata builds up.
1744 static void do_waker(struct work_struct *ws)
1746 struct cache *cache = container_of(to_delayed_work(ws), struct cache, waker);
1747 policy_tick(cache->policy);
1749 queue_delayed_work(cache->wq, &cache->waker, COMMIT_PERIOD);
1752 /*----------------------------------------------------------------*/
1754 static int is_congested(struct dm_dev *dev, int bdi_bits)
1756 struct request_queue *q = bdev_get_queue(dev->bdev);
1757 return bdi_congested(&q->backing_dev_info, bdi_bits);
1760 static int cache_is_congested(struct dm_target_callbacks *cb, int bdi_bits)
1762 struct cache *cache = container_of(cb, struct cache, callbacks);
1764 return is_congested(cache->origin_dev, bdi_bits) ||
1765 is_congested(cache->cache_dev, bdi_bits);
1768 /*----------------------------------------------------------------
1770 *--------------------------------------------------------------*/
1773 * This function gets called on the error paths of the constructor, so we
1774 * have to cope with a partially initialised struct.
1776 static void destroy(struct cache *cache)
1780 if (cache->next_migration)
1781 mempool_free(cache->next_migration, cache->migration_pool);
1783 if (cache->migration_pool)
1784 mempool_destroy(cache->migration_pool);
1786 if (cache->all_io_ds)
1787 dm_deferred_set_destroy(cache->all_io_ds);
1790 dm_bio_prison_destroy(cache->prison);
1793 destroy_workqueue(cache->wq);
1795 if (cache->dirty_bitset)
1796 free_bitset(cache->dirty_bitset);
1798 if (cache->discard_bitset)
1799 free_bitset(cache->discard_bitset);
1802 dm_kcopyd_client_destroy(cache->copier);
1805 dm_cache_metadata_close(cache->cmd);
1807 if (cache->metadata_dev)
1808 dm_put_device(cache->ti, cache->metadata_dev);
1810 if (cache->origin_dev)
1811 dm_put_device(cache->ti, cache->origin_dev);
1813 if (cache->cache_dev)
1814 dm_put_device(cache->ti, cache->cache_dev);
1817 dm_cache_policy_destroy(cache->policy);
1819 for (i = 0; i < cache->nr_ctr_args ; i++)
1820 kfree(cache->ctr_args[i]);
1821 kfree(cache->ctr_args);
1826 static void cache_dtr(struct dm_target *ti)
1828 struct cache *cache = ti->private;
1833 static sector_t get_dev_size(struct dm_dev *dev)
1835 return i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT;
1838 /*----------------------------------------------------------------*/
1841 * Construct a cache device mapping.
1843 * cache <metadata dev> <cache dev> <origin dev> <block size>
1844 * <#feature args> [<feature arg>]*
1845 * <policy> <#policy args> [<policy arg>]*
1847 * metadata dev : fast device holding the persistent metadata
1848 * cache dev : fast device holding cached data blocks
1849 * origin dev : slow device holding original data blocks
1850 * block size : cache unit size in sectors
1852 * #feature args : number of feature arguments passed
1853 * feature args : writethrough. (The default is writeback.)
1855 * policy : the replacement policy to use
1856 * #policy args : an even number of policy arguments corresponding
1857 * to key/value pairs passed to the policy
1858 * policy args : key/value pairs passed to the policy
1859 * E.g. 'sequential_threshold 1024'
1860 * See cache-policies.txt for details.
1862 * Optional feature arguments are:
1863 * writethrough : write through caching that prohibits cache block
1864 * content from being different from origin block content.
1865 * Without this argument, the default behaviour is to write
1866 * back cache block contents later for performance reasons,
1867 * so they may differ from the corresponding origin blocks.
1870 struct dm_target *ti;
1872 struct dm_dev *metadata_dev;
1874 struct dm_dev *cache_dev;
1875 sector_t cache_sectors;
1877 struct dm_dev *origin_dev;
1878 sector_t origin_sectors;
1880 uint32_t block_size;
1882 const char *policy_name;
1884 const char **policy_argv;
1886 struct cache_features features;
1889 static void destroy_cache_args(struct cache_args *ca)
1891 if (ca->metadata_dev)
1892 dm_put_device(ca->ti, ca->metadata_dev);
1895 dm_put_device(ca->ti, ca->cache_dev);
1898 dm_put_device(ca->ti, ca->origin_dev);
1903 static bool at_least_one_arg(struct dm_arg_set *as, char **error)
1906 *error = "Insufficient args";
1913 static int parse_metadata_dev(struct cache_args *ca, struct dm_arg_set *as,
1917 sector_t metadata_dev_size;
1918 char b[BDEVNAME_SIZE];
1920 if (!at_least_one_arg(as, error))
1923 r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
1926 *error = "Error opening metadata device";
1930 metadata_dev_size = get_dev_size(ca->metadata_dev);
1931 if (metadata_dev_size > DM_CACHE_METADATA_MAX_SECTORS_WARNING)
1932 DMWARN("Metadata device %s is larger than %u sectors: excess space will not be used.",
1933 bdevname(ca->metadata_dev->bdev, b), THIN_METADATA_MAX_SECTORS);
1938 static int parse_cache_dev(struct cache_args *ca, struct dm_arg_set *as,
1943 if (!at_least_one_arg(as, error))
1946 r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
1949 *error = "Error opening cache device";
1952 ca->cache_sectors = get_dev_size(ca->cache_dev);
1957 static int parse_origin_dev(struct cache_args *ca, struct dm_arg_set *as,
1962 if (!at_least_one_arg(as, error))
1965 r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
1968 *error = "Error opening origin device";
1972 ca->origin_sectors = get_dev_size(ca->origin_dev);
1973 if (ca->ti->len > ca->origin_sectors) {
1974 *error = "Device size larger than cached device";
1981 static int parse_block_size(struct cache_args *ca, struct dm_arg_set *as,
1984 unsigned long block_size;
1986 if (!at_least_one_arg(as, error))
1989 if (kstrtoul(dm_shift_arg(as), 10, &block_size) || !block_size ||
1990 block_size < DATA_DEV_BLOCK_SIZE_MIN_SECTORS ||
1991 block_size > DATA_DEV_BLOCK_SIZE_MAX_SECTORS ||
1992 block_size & (DATA_DEV_BLOCK_SIZE_MIN_SECTORS - 1)) {
1993 *error = "Invalid data block size";
1997 if (block_size > ca->cache_sectors) {
1998 *error = "Data block size is larger than the cache device";
2002 ca->block_size = block_size;
2007 static void init_features(struct cache_features *cf)
2009 cf->mode = CM_WRITE;
2010 cf->io_mode = CM_IO_WRITEBACK;
2013 static int parse_features(struct cache_args *ca, struct dm_arg_set *as,
2016 static struct dm_arg _args[] = {
2017 {0, 1, "Invalid number of cache feature arguments"},
2023 struct cache_features *cf = &ca->features;
2027 r = dm_read_arg_group(_args, as, &argc, error);
2032 arg = dm_shift_arg(as);
2034 if (!strcasecmp(arg, "writeback"))
2035 cf->io_mode = CM_IO_WRITEBACK;
2037 else if (!strcasecmp(arg, "writethrough"))
2038 cf->io_mode = CM_IO_WRITETHROUGH;
2040 else if (!strcasecmp(arg, "passthrough"))
2041 cf->io_mode = CM_IO_PASSTHROUGH;
2044 *error = "Unrecognised cache feature requested";
2052 static int parse_policy(struct cache_args *ca, struct dm_arg_set *as,
2055 static struct dm_arg _args[] = {
2056 {0, 1024, "Invalid number of policy arguments"},
2061 if (!at_least_one_arg(as, error))
2064 ca->policy_name = dm_shift_arg(as);
2066 r = dm_read_arg_group(_args, as, &ca->policy_argc, error);
2070 ca->policy_argv = (const char **)as->argv;
2071 dm_consume_args(as, ca->policy_argc);
2076 static int parse_cache_args(struct cache_args *ca, int argc, char **argv,
2080 struct dm_arg_set as;
2085 r = parse_metadata_dev(ca, &as, error);
2089 r = parse_cache_dev(ca, &as, error);
2093 r = parse_origin_dev(ca, &as, error);
2097 r = parse_block_size(ca, &as, error);
2101 r = parse_features(ca, &as, error);
2105 r = parse_policy(ca, &as, error);
2112 /*----------------------------------------------------------------*/
2114 static struct kmem_cache *migration_cache;
2116 #define NOT_CORE_OPTION 1
2118 static int process_config_option(struct cache *cache, const char *key, const char *value)
2122 if (!strcasecmp(key, "migration_threshold")) {
2123 if (kstrtoul(value, 10, &tmp))
2126 cache->migration_threshold = tmp;
2130 return NOT_CORE_OPTION;
2133 static int set_config_value(struct cache *cache, const char *key, const char *value)
2135 int r = process_config_option(cache, key, value);
2137 if (r == NOT_CORE_OPTION)
2138 r = policy_set_config_value(cache->policy, key, value);
2141 DMWARN("bad config value for %s: %s", key, value);
2146 static int set_config_values(struct cache *cache, int argc, const char **argv)
2151 DMWARN("Odd number of policy arguments given but they should be <key> <value> pairs.");
2156 r = set_config_value(cache, argv[0], argv[1]);
2167 static int create_cache_policy(struct cache *cache, struct cache_args *ca,
2170 struct dm_cache_policy *p = dm_cache_policy_create(ca->policy_name,
2172 cache->origin_sectors,
2173 cache->sectors_per_block);
2175 *error = "Error creating cache's policy";
2183 #define DEFAULT_MIGRATION_THRESHOLD 2048
2185 static int cache_create(struct cache_args *ca, struct cache **result)
2188 char **error = &ca->ti->error;
2189 struct cache *cache;
2190 struct dm_target *ti = ca->ti;
2191 dm_block_t origin_blocks;
2192 struct dm_cache_metadata *cmd;
2193 bool may_format = ca->features.mode == CM_WRITE;
2195 cache = kzalloc(sizeof(*cache), GFP_KERNEL);
2200 ti->private = cache;
2201 ti->num_flush_bios = 2;
2202 ti->flush_supported = true;
2204 ti->num_discard_bios = 1;
2205 ti->discards_supported = true;
2206 ti->discard_zeroes_data_unsupported = true;
2207 /* Discard bios must be split on a block boundary */
2208 ti->split_discard_bios = true;
2210 cache->features = ca->features;
2211 ti->per_bio_data_size = get_per_bio_data_size(cache);
2213 cache->callbacks.congested_fn = cache_is_congested;
2214 dm_table_add_target_callbacks(ti->table, &cache->callbacks);
2216 cache->metadata_dev = ca->metadata_dev;
2217 cache->origin_dev = ca->origin_dev;
2218 cache->cache_dev = ca->cache_dev;
2220 ca->metadata_dev = ca->origin_dev = ca->cache_dev = NULL;
2222 /* FIXME: factor out this whole section */
2223 origin_blocks = cache->origin_sectors = ca->origin_sectors;
2224 origin_blocks = block_div(origin_blocks, ca->block_size);
2225 cache->origin_blocks = to_oblock(origin_blocks);
2227 cache->sectors_per_block = ca->block_size;
2228 if (dm_set_target_max_io_len(ti, cache->sectors_per_block)) {
2233 if (ca->block_size & (ca->block_size - 1)) {
2234 dm_block_t cache_size = ca->cache_sectors;
2236 cache->sectors_per_block_shift = -1;
2237 cache_size = block_div(cache_size, ca->block_size);
2238 cache->cache_size = to_cblock(cache_size);
2240 cache->sectors_per_block_shift = __ffs(ca->block_size);
2241 cache->cache_size = to_cblock(ca->cache_sectors >> cache->sectors_per_block_shift);
2244 r = create_cache_policy(cache, ca, error);
2248 cache->policy_nr_args = ca->policy_argc;
2249 cache->migration_threshold = DEFAULT_MIGRATION_THRESHOLD;
2251 r = set_config_values(cache, ca->policy_argc, ca->policy_argv);
2253 *error = "Error setting cache policy's config values";
2257 cmd = dm_cache_metadata_open(cache->metadata_dev->bdev,
2258 ca->block_size, may_format,
2259 dm_cache_policy_get_hint_size(cache->policy));
2261 *error = "Error creating metadata object";
2267 if (passthrough_mode(&cache->features)) {
2270 r = dm_cache_metadata_all_clean(cache->cmd, &all_clean);
2272 *error = "dm_cache_metadata_all_clean() failed";
2277 *error = "Cannot enter passthrough mode unless all blocks are clean";
2283 spin_lock_init(&cache->lock);
2284 bio_list_init(&cache->deferred_bios);
2285 bio_list_init(&cache->deferred_flush_bios);
2286 bio_list_init(&cache->deferred_writethrough_bios);
2287 INIT_LIST_HEAD(&cache->quiesced_migrations);
2288 INIT_LIST_HEAD(&cache->completed_migrations);
2289 INIT_LIST_HEAD(&cache->need_commit_migrations);
2290 atomic_set(&cache->nr_migrations, 0);
2291 init_waitqueue_head(&cache->migration_wait);
2293 init_waitqueue_head(&cache->quiescing_wait);
2294 atomic_set(&cache->quiescing, 0);
2295 atomic_set(&cache->quiescing_ack, 0);
2298 atomic_set(&cache->nr_dirty, 0);
2299 cache->dirty_bitset = alloc_bitset(from_cblock(cache->cache_size));
2300 if (!cache->dirty_bitset) {
2301 *error = "could not allocate dirty bitset";
2304 clear_bitset(cache->dirty_bitset, from_cblock(cache->cache_size));
2306 cache->discard_nr_blocks = cache->origin_blocks;
2307 cache->discard_bitset = alloc_bitset(from_oblock(cache->discard_nr_blocks));
2308 if (!cache->discard_bitset) {
2309 *error = "could not allocate discard bitset";
2312 clear_bitset(cache->discard_bitset, from_oblock(cache->discard_nr_blocks));
2314 cache->copier = dm_kcopyd_client_create(&dm_kcopyd_throttle);
2315 if (IS_ERR(cache->copier)) {
2316 *error = "could not create kcopyd client";
2317 r = PTR_ERR(cache->copier);
2321 cache->wq = alloc_ordered_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM);
2323 *error = "could not create workqueue for metadata object";
2326 INIT_WORK(&cache->worker, do_worker);
2327 INIT_DELAYED_WORK(&cache->waker, do_waker);
2328 cache->last_commit_jiffies = jiffies;
2330 cache->prison = dm_bio_prison_create(PRISON_CELLS);
2331 if (!cache->prison) {
2332 *error = "could not create bio prison";
2336 cache->all_io_ds = dm_deferred_set_create();
2337 if (!cache->all_io_ds) {
2338 *error = "could not create all_io deferred set";
2342 cache->migration_pool = mempool_create_slab_pool(MIGRATION_POOL_SIZE,
2344 if (!cache->migration_pool) {
2345 *error = "Error creating cache's migration mempool";
2349 cache->next_migration = NULL;
2351 cache->need_tick_bio = true;
2352 cache->sized = false;
2353 cache->invalidate = false;
2354 cache->commit_requested = false;
2355 cache->loaded_mappings = false;
2356 cache->loaded_discards = false;
2360 atomic_set(&cache->stats.demotion, 0);
2361 atomic_set(&cache->stats.promotion, 0);
2362 atomic_set(&cache->stats.copies_avoided, 0);
2363 atomic_set(&cache->stats.cache_cell_clash, 0);
2364 atomic_set(&cache->stats.commit_count, 0);
2365 atomic_set(&cache->stats.discard_count, 0);
2367 spin_lock_init(&cache->invalidation_lock);
2368 INIT_LIST_HEAD(&cache->invalidation_requests);
2378 static int copy_ctr_args(struct cache *cache, int argc, const char **argv)
2383 copy = kcalloc(argc, sizeof(*copy), GFP_KERNEL);
2386 for (i = 0; i < argc; i++) {
2387 copy[i] = kstrdup(argv[i], GFP_KERNEL);
2396 cache->nr_ctr_args = argc;
2397 cache->ctr_args = copy;
2402 static int cache_ctr(struct dm_target *ti, unsigned argc, char **argv)
2405 struct cache_args *ca;
2406 struct cache *cache = NULL;
2408 ca = kzalloc(sizeof(*ca), GFP_KERNEL);
2410 ti->error = "Error allocating memory for cache";
2415 r = parse_cache_args(ca, argc, argv, &ti->error);
2419 r = cache_create(ca, &cache);
2423 r = copy_ctr_args(cache, argc - 3, (const char **)argv + 3);
2429 ti->private = cache;
2432 destroy_cache_args(ca);
2436 static int __cache_map(struct cache *cache, struct bio *bio, struct dm_bio_prison_cell **cell)
2439 dm_oblock_t block = get_bio_block(cache, bio);
2440 size_t pb_data_size = get_per_bio_data_size(cache);
2441 bool can_migrate = false;
2442 bool discarded_block;
2443 struct policy_result lookup_result;
2444 struct per_bio_data *pb = init_per_bio_data(bio, pb_data_size);
2446 if (unlikely(from_oblock(block) >= from_oblock(cache->origin_blocks))) {
2448 * This can only occur if the io goes to a partial block at
2449 * the end of the origin device. We don't cache these.
2450 * Just remap to the origin and carry on.
2452 remap_to_origin(cache, bio);
2453 return DM_MAPIO_REMAPPED;
2456 if (bio->bi_rw & (REQ_FLUSH | REQ_FUA | REQ_DISCARD)) {
2457 defer_bio(cache, bio);
2458 return DM_MAPIO_SUBMITTED;
2462 * Check to see if that block is currently migrating.
2464 *cell = alloc_prison_cell(cache);
2466 defer_bio(cache, bio);
2467 return DM_MAPIO_SUBMITTED;
2470 r = bio_detain(cache, block, bio, *cell,
2471 (cell_free_fn) free_prison_cell,
2475 defer_bio(cache, bio);
2477 return DM_MAPIO_SUBMITTED;
2480 discarded_block = is_discarded_oblock(cache, block);
2482 r = policy_map(cache->policy, block, false, can_migrate, discarded_block,
2483 bio, &lookup_result);
2484 if (r == -EWOULDBLOCK) {
2485 cell_defer(cache, *cell, true);
2486 return DM_MAPIO_SUBMITTED;
2489 DMERR_LIMIT("Unexpected return from cache replacement policy: %d", r);
2490 cell_defer(cache, *cell, false);
2492 return DM_MAPIO_SUBMITTED;
2495 r = DM_MAPIO_REMAPPED;
2496 switch (lookup_result.op) {
2498 if (passthrough_mode(&cache->features)) {
2499 if (bio_data_dir(bio) == WRITE) {
2501 * We need to invalidate this block, so
2502 * defer for the worker thread.
2504 cell_defer(cache, *cell, true);
2505 r = DM_MAPIO_SUBMITTED;
2508 inc_miss_counter(cache, bio);
2509 remap_to_origin_clear_discard(cache, bio, block);
2513 inc_hit_counter(cache, bio);
2514 if (bio_data_dir(bio) == WRITE && writethrough_mode(&cache->features) &&
2515 !is_dirty(cache, lookup_result.cblock))
2516 remap_to_origin_then_cache(cache, bio, block, lookup_result.cblock);
2518 remap_to_cache_dirty(cache, bio, block, lookup_result.cblock);
2523 inc_miss_counter(cache, bio);
2524 if (pb->req_nr != 0) {
2526 * This is a duplicate writethrough io that is no
2527 * longer needed because the block has been demoted.
2530 cell_defer(cache, *cell, false);
2531 r = DM_MAPIO_SUBMITTED;
2534 remap_to_origin_clear_discard(cache, bio, block);
2539 DMERR_LIMIT("%s: erroring bio: unknown policy op: %u", __func__,
2540 (unsigned) lookup_result.op);
2541 cell_defer(cache, *cell, false);
2543 r = DM_MAPIO_SUBMITTED;
2549 static int cache_map(struct dm_target *ti, struct bio *bio)
2552 struct dm_bio_prison_cell *cell;
2553 struct cache *cache = ti->private;
2555 r = __cache_map(cache, bio, &cell);
2556 if (r == DM_MAPIO_REMAPPED) {
2557 inc_ds(cache, bio, cell);
2558 cell_defer(cache, cell, false);
2564 static int cache_end_io(struct dm_target *ti, struct bio *bio, int error)
2566 struct cache *cache = ti->private;
2567 unsigned long flags;
2568 size_t pb_data_size = get_per_bio_data_size(cache);
2569 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
2572 policy_tick(cache->policy);
2574 spin_lock_irqsave(&cache->lock, flags);
2575 cache->need_tick_bio = true;
2576 spin_unlock_irqrestore(&cache->lock, flags);
2579 check_for_quiesced_migrations(cache, pb);
2584 static int write_dirty_bitset(struct cache *cache)
2588 for (i = 0; i < from_cblock(cache->cache_size); i++) {
2589 r = dm_cache_set_dirty(cache->cmd, to_cblock(i),
2590 is_dirty(cache, to_cblock(i)));
2598 static int write_discard_bitset(struct cache *cache)
2602 r = dm_cache_discard_bitset_resize(cache->cmd, cache->sectors_per_block,
2603 cache->origin_blocks);
2605 DMERR("could not resize on-disk discard bitset");
2609 for (i = 0; i < from_oblock(cache->discard_nr_blocks); i++) {
2610 r = dm_cache_set_discard(cache->cmd, to_oblock(i),
2611 is_discarded(cache, to_oblock(i)));
2620 * returns true on success
2622 static bool sync_metadata(struct cache *cache)
2626 r1 = write_dirty_bitset(cache);
2628 DMERR("could not write dirty bitset");
2630 r2 = write_discard_bitset(cache);
2632 DMERR("could not write discard bitset");
2636 r3 = dm_cache_write_hints(cache->cmd, cache->policy);
2638 DMERR("could not write hints");
2641 * If writing the above metadata failed, we still commit, but don't
2642 * set the clean shutdown flag. This will effectively force every
2643 * dirty bit to be set on reload.
2645 r4 = dm_cache_commit(cache->cmd, !r1 && !r2 && !r3);
2647 DMERR("could not write cache metadata. Data loss may occur.");
2649 return !r1 && !r2 && !r3 && !r4;
2652 static void cache_postsuspend(struct dm_target *ti)
2654 struct cache *cache = ti->private;
2656 start_quiescing(cache);
2657 wait_for_migrations(cache);
2659 requeue_deferred_io(cache);
2660 stop_quiescing(cache);
2662 (void) sync_metadata(cache);
2665 static int load_mapping(void *context, dm_oblock_t oblock, dm_cblock_t cblock,
2666 bool dirty, uint32_t hint, bool hint_valid)
2669 struct cache *cache = context;
2671 r = policy_load_mapping(cache->policy, oblock, cblock, hint, hint_valid);
2676 set_dirty(cache, oblock, cblock);
2678 clear_dirty(cache, oblock, cblock);
2683 static int load_discard(void *context, sector_t discard_block_size,
2684 dm_oblock_t oblock, bool discard)
2686 struct cache *cache = context;
2689 set_discard(cache, oblock);
2691 clear_discard(cache, oblock);
2696 static dm_cblock_t get_cache_dev_size(struct cache *cache)
2698 sector_t size = get_dev_size(cache->cache_dev);
2699 (void) sector_div(size, cache->sectors_per_block);
2700 return to_cblock(size);
2703 static bool can_resize(struct cache *cache, dm_cblock_t new_size)
2705 if (from_cblock(new_size) > from_cblock(cache->cache_size))
2709 * We can't drop a dirty block when shrinking the cache.
2711 while (from_cblock(new_size) < from_cblock(cache->cache_size)) {
2712 new_size = to_cblock(from_cblock(new_size) + 1);
2713 if (is_dirty(cache, new_size)) {
2714 DMERR("unable to shrink cache; cache block %llu is dirty",
2715 (unsigned long long) from_cblock(new_size));
2723 static int resize_cache_dev(struct cache *cache, dm_cblock_t new_size)
2727 r = dm_cache_resize(cache->cmd, new_size);
2729 DMERR("could not resize cache metadata");
2733 cache->cache_size = new_size;
2738 static int cache_preresume(struct dm_target *ti)
2741 struct cache *cache = ti->private;
2742 dm_cblock_t csize = get_cache_dev_size(cache);
2745 * Check to see if the cache has resized.
2747 if (!cache->sized) {
2748 r = resize_cache_dev(cache, csize);
2752 cache->sized = true;
2754 } else if (csize != cache->cache_size) {
2755 if (!can_resize(cache, csize))
2758 r = resize_cache_dev(cache, csize);
2763 if (!cache->loaded_mappings) {
2764 r = dm_cache_load_mappings(cache->cmd, cache->policy,
2765 load_mapping, cache);
2767 DMERR("could not load cache mappings");
2771 cache->loaded_mappings = true;
2774 if (!cache->loaded_discards) {
2775 r = dm_cache_load_discards(cache->cmd, load_discard, cache);
2777 DMERR("could not load origin discards");
2781 cache->loaded_discards = true;
2787 static void cache_resume(struct dm_target *ti)
2789 struct cache *cache = ti->private;
2791 cache->need_tick_bio = true;
2792 do_waker(&cache->waker.work);
2798 * <metadata block size> <#used metadata blocks>/<#total metadata blocks>
2799 * <cache block size> <#used cache blocks>/<#total cache blocks>
2800 * <#read hits> <#read misses> <#write hits> <#write misses>
2801 * <#demotions> <#promotions> <#dirty>
2802 * <#features> <features>*
2803 * <#core args> <core args>
2804 * <policy name> <#policy args> <policy args>*
2806 static void cache_status(struct dm_target *ti, status_type_t type,
2807 unsigned status_flags, char *result, unsigned maxlen)
2812 dm_block_t nr_free_blocks_metadata = 0;
2813 dm_block_t nr_blocks_metadata = 0;
2814 char buf[BDEVNAME_SIZE];
2815 struct cache *cache = ti->private;
2816 dm_cblock_t residency;
2819 case STATUSTYPE_INFO:
2820 /* Commit to ensure statistics aren't out-of-date */
2821 if (!(status_flags & DM_STATUS_NOFLUSH_FLAG) && !dm_suspended(ti)) {
2822 r = dm_cache_commit(cache->cmd, false);
2824 DMERR("could not commit metadata for accurate status");
2827 r = dm_cache_get_free_metadata_block_count(cache->cmd,
2828 &nr_free_blocks_metadata);
2830 DMERR("could not get metadata free block count");
2834 r = dm_cache_get_metadata_dev_size(cache->cmd, &nr_blocks_metadata);
2836 DMERR("could not get metadata device size");
2840 residency = policy_residency(cache->policy);
2842 DMEMIT("%u %llu/%llu %u %llu/%llu %u %u %u %u %u %u %lu ",
2843 (unsigned)DM_CACHE_METADATA_BLOCK_SIZE,
2844 (unsigned long long)(nr_blocks_metadata - nr_free_blocks_metadata),
2845 (unsigned long long)nr_blocks_metadata,
2846 cache->sectors_per_block,
2847 (unsigned long long) from_cblock(residency),
2848 (unsigned long long) from_cblock(cache->cache_size),
2849 (unsigned) atomic_read(&cache->stats.read_hit),
2850 (unsigned) atomic_read(&cache->stats.read_miss),
2851 (unsigned) atomic_read(&cache->stats.write_hit),
2852 (unsigned) atomic_read(&cache->stats.write_miss),
2853 (unsigned) atomic_read(&cache->stats.demotion),
2854 (unsigned) atomic_read(&cache->stats.promotion),
2855 (unsigned long) atomic_read(&cache->nr_dirty));
2857 if (writethrough_mode(&cache->features))
2858 DMEMIT("1 writethrough ");
2860 else if (passthrough_mode(&cache->features))
2861 DMEMIT("1 passthrough ");
2863 else if (writeback_mode(&cache->features))
2864 DMEMIT("1 writeback ");
2867 DMERR("internal error: unknown io mode: %d", (int) cache->features.io_mode);
2871 DMEMIT("2 migration_threshold %llu ", (unsigned long long) cache->migration_threshold);
2873 DMEMIT("%s ", dm_cache_policy_get_name(cache->policy));
2875 r = policy_emit_config_values(cache->policy, result + sz, maxlen - sz);
2877 DMERR("policy_emit_config_values returned %d", r);
2882 case STATUSTYPE_TABLE:
2883 format_dev_t(buf, cache->metadata_dev->bdev->bd_dev);
2885 format_dev_t(buf, cache->cache_dev->bdev->bd_dev);
2887 format_dev_t(buf, cache->origin_dev->bdev->bd_dev);
2890 for (i = 0; i < cache->nr_ctr_args - 1; i++)
2891 DMEMIT(" %s", cache->ctr_args[i]);
2892 if (cache->nr_ctr_args)
2893 DMEMIT(" %s", cache->ctr_args[cache->nr_ctr_args - 1]);
2903 * A cache block range can take two forms:
2905 * i) A single cblock, eg. '3456'
2906 * ii) A begin and end cblock with dots between, eg. 123-234
2908 static int parse_cblock_range(struct cache *cache, const char *str,
2909 struct cblock_range *result)
2916 * Try and parse form (ii) first.
2918 r = sscanf(str, "%llu-%llu%c", &b, &e, &dummy);
2923 result->begin = to_cblock(b);
2924 result->end = to_cblock(e);
2929 * That didn't work, try form (i).
2931 r = sscanf(str, "%llu%c", &b, &dummy);
2936 result->begin = to_cblock(b);
2937 result->end = to_cblock(from_cblock(result->begin) + 1u);
2941 DMERR("invalid cblock range '%s'", str);
2945 static int validate_cblock_range(struct cache *cache, struct cblock_range *range)
2947 uint64_t b = from_cblock(range->begin);
2948 uint64_t e = from_cblock(range->end);
2949 uint64_t n = from_cblock(cache->cache_size);
2952 DMERR("begin cblock out of range: %llu >= %llu", b, n);
2957 DMERR("end cblock out of range: %llu > %llu", e, n);
2962 DMERR("invalid cblock range: %llu >= %llu", b, e);
2969 static int request_invalidation(struct cache *cache, struct cblock_range *range)
2971 struct invalidation_request req;
2973 INIT_LIST_HEAD(&req.list);
2974 req.cblocks = range;
2975 atomic_set(&req.complete, 0);
2977 init_waitqueue_head(&req.result_wait);
2979 spin_lock(&cache->invalidation_lock);
2980 list_add(&req.list, &cache->invalidation_requests);
2981 spin_unlock(&cache->invalidation_lock);
2984 wait_event(req.result_wait, atomic_read(&req.complete));
2988 static int process_invalidate_cblocks_message(struct cache *cache, unsigned count,
2989 const char **cblock_ranges)
2993 struct cblock_range range;
2995 if (!passthrough_mode(&cache->features)) {
2996 DMERR("cache has to be in passthrough mode for invalidation");
3000 for (i = 0; i < count; i++) {
3001 r = parse_cblock_range(cache, cblock_ranges[i], &range);
3005 r = validate_cblock_range(cache, &range);
3010 * Pass begin and end origin blocks to the worker and wake it.
3012 r = request_invalidation(cache, &range);
3024 * "invalidate_cblocks [(<begin>)|(<begin>-<end>)]*
3026 * The key migration_threshold is supported by the cache target core.
3028 static int cache_message(struct dm_target *ti, unsigned argc, char **argv)
3030 struct cache *cache = ti->private;
3035 if (!strcasecmp(argv[0], "invalidate_cblocks"))
3036 return process_invalidate_cblocks_message(cache, argc - 1, (const char **) argv + 1);
3041 return set_config_value(cache, argv[0], argv[1]);
3044 static int cache_iterate_devices(struct dm_target *ti,
3045 iterate_devices_callout_fn fn, void *data)
3048 struct cache *cache = ti->private;
3050 r = fn(ti, cache->cache_dev, 0, get_dev_size(cache->cache_dev), data);
3052 r = fn(ti, cache->origin_dev, 0, ti->len, data);
3058 * We assume I/O is going to the origin (which is the volume
3059 * more likely to have restrictions e.g. by being striped).
3060 * (Looking up the exact location of the data would be expensive
3061 * and could always be out of date by the time the bio is submitted.)
3063 static int cache_bvec_merge(struct dm_target *ti,
3064 struct bvec_merge_data *bvm,
3065 struct bio_vec *biovec, int max_size)
3067 struct cache *cache = ti->private;
3068 struct request_queue *q = bdev_get_queue(cache->origin_dev->bdev);
3070 if (!q->merge_bvec_fn)
3073 bvm->bi_bdev = cache->origin_dev->bdev;
3074 return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
3077 static void set_discard_limits(struct cache *cache, struct queue_limits *limits)
3080 * FIXME: these limits may be incompatible with the cache device
3082 limits->max_discard_sectors = cache->sectors_per_block;
3083 limits->discard_granularity = cache->sectors_per_block << SECTOR_SHIFT;
3086 static void cache_io_hints(struct dm_target *ti, struct queue_limits *limits)
3088 struct cache *cache = ti->private;
3089 uint64_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;
3092 * If the system-determined stacked limits are compatible with the
3093 * cache's blocksize (io_opt is a factor) do not override them.
3095 if (io_opt_sectors < cache->sectors_per_block ||
3096 do_div(io_opt_sectors, cache->sectors_per_block)) {
3097 blk_limits_io_min(limits, cache->sectors_per_block << SECTOR_SHIFT);
3098 blk_limits_io_opt(limits, cache->sectors_per_block << SECTOR_SHIFT);
3100 set_discard_limits(cache, limits);
3103 /*----------------------------------------------------------------*/
3105 static struct target_type cache_target = {
3107 .version = {1, 5, 0},
3108 .module = THIS_MODULE,
3112 .end_io = cache_end_io,
3113 .postsuspend = cache_postsuspend,
3114 .preresume = cache_preresume,
3115 .resume = cache_resume,
3116 .status = cache_status,
3117 .message = cache_message,
3118 .iterate_devices = cache_iterate_devices,
3119 .merge = cache_bvec_merge,
3120 .io_hints = cache_io_hints,
3123 static int __init dm_cache_init(void)
3127 r = dm_register_target(&cache_target);
3129 DMERR("cache target registration failed: %d", r);
3133 migration_cache = KMEM_CACHE(dm_cache_migration, 0);
3134 if (!migration_cache) {
3135 dm_unregister_target(&cache_target);
3142 static void __exit dm_cache_exit(void)
3144 dm_unregister_target(&cache_target);
3145 kmem_cache_destroy(migration_cache);
3148 module_init(dm_cache_init);
3149 module_exit(dm_cache_exit);
3151 MODULE_DESCRIPTION(DM_NAME " cache target");
3152 MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
3153 MODULE_LICENSE("GPL");