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
234 dm_cblock_t nr_dirty;
235 unsigned long *dirty_bitset;
238 * origin_blocks entries, discarded if set.
240 dm_dblock_t discard_nr_blocks;
241 unsigned long *discard_bitset;
242 uint32_t discard_block_size; /* a power of 2 times sectors per block */
245 * Rather than reconstructing the table line for the status we just
246 * save it and regurgitate.
248 unsigned nr_ctr_args;
249 const char **ctr_args;
251 struct dm_kcopyd_client *copier;
252 struct workqueue_struct *wq;
253 struct work_struct worker;
255 struct delayed_work waker;
256 unsigned long last_commit_jiffies;
258 struct dm_bio_prison *prison;
259 struct dm_deferred_set *all_io_ds;
261 mempool_t *migration_pool;
262 struct dm_cache_migration *next_migration;
264 struct dm_cache_policy *policy;
265 unsigned policy_nr_args;
267 bool need_tick_bio:1;
270 bool commit_requested:1;
271 bool loaded_mappings:1;
272 bool loaded_discards:1;
275 * Cache features such as write-through.
277 struct cache_features features;
279 struct cache_stats stats;
282 * Invalidation fields.
284 spinlock_t invalidation_lock;
285 struct list_head invalidation_requests;
288 struct per_bio_data {
291 struct dm_deferred_entry *all_io_entry;
292 struct dm_hook_info hook_info;
295 * writethrough fields. These MUST remain at the end of this
296 * structure and the 'cache' member must be the first as it
297 * is used to determine the offset of the writethrough fields.
301 struct dm_bio_details bio_details;
304 struct dm_cache_migration {
305 struct list_head list;
308 unsigned long start_jiffies;
309 dm_oblock_t old_oblock;
310 dm_oblock_t new_oblock;
317 bool requeue_holder:1;
320 struct dm_bio_prison_cell *old_ocell;
321 struct dm_bio_prison_cell *new_ocell;
325 * Processing a bio in the worker thread may require these memory
326 * allocations. We prealloc to avoid deadlocks (the same worker thread
327 * frees them back to the mempool).
330 struct dm_cache_migration *mg;
331 struct dm_bio_prison_cell *cell1;
332 struct dm_bio_prison_cell *cell2;
335 static void wake_worker(struct cache *cache)
337 queue_work(cache->wq, &cache->worker);
340 /*----------------------------------------------------------------*/
342 static struct dm_bio_prison_cell *alloc_prison_cell(struct cache *cache)
344 /* FIXME: change to use a local slab. */
345 return dm_bio_prison_alloc_cell(cache->prison, GFP_NOWAIT);
348 static void free_prison_cell(struct cache *cache, struct dm_bio_prison_cell *cell)
350 dm_bio_prison_free_cell(cache->prison, cell);
353 static int prealloc_data_structs(struct cache *cache, struct prealloc *p)
356 p->mg = mempool_alloc(cache->migration_pool, GFP_NOWAIT);
362 p->cell1 = alloc_prison_cell(cache);
368 p->cell2 = alloc_prison_cell(cache);
376 static void prealloc_free_structs(struct cache *cache, struct prealloc *p)
379 free_prison_cell(cache, p->cell2);
382 free_prison_cell(cache, p->cell1);
385 mempool_free(p->mg, cache->migration_pool);
388 static struct dm_cache_migration *prealloc_get_migration(struct prealloc *p)
390 struct dm_cache_migration *mg = p->mg;
399 * You must have a cell within the prealloc struct to return. If not this
400 * function will BUG() rather than returning NULL.
402 static struct dm_bio_prison_cell *prealloc_get_cell(struct prealloc *p)
404 struct dm_bio_prison_cell *r = NULL;
410 } else if (p->cell2) {
420 * You can't have more than two cells in a prealloc struct. BUG() will be
421 * called if you try and overfill.
423 static void prealloc_put_cell(struct prealloc *p, struct dm_bio_prison_cell *cell)
435 /*----------------------------------------------------------------*/
437 static void build_key(dm_oblock_t oblock, struct dm_cell_key *key)
441 key->block = from_oblock(oblock);
445 * The caller hands in a preallocated cell, and a free function for it.
446 * The cell will be freed if there's an error, or if it wasn't used because
447 * a cell with that key already exists.
449 typedef void (*cell_free_fn)(void *context, struct dm_bio_prison_cell *cell);
451 static int bio_detain(struct cache *cache, dm_oblock_t oblock,
452 struct bio *bio, struct dm_bio_prison_cell *cell_prealloc,
453 cell_free_fn free_fn, void *free_context,
454 struct dm_bio_prison_cell **cell_result)
457 struct dm_cell_key key;
459 build_key(oblock, &key);
460 r = dm_bio_detain(cache->prison, &key, bio, cell_prealloc, cell_result);
462 free_fn(free_context, cell_prealloc);
467 static int get_cell(struct cache *cache,
469 struct prealloc *structs,
470 struct dm_bio_prison_cell **cell_result)
473 struct dm_cell_key key;
474 struct dm_bio_prison_cell *cell_prealloc;
476 cell_prealloc = prealloc_get_cell(structs);
478 build_key(oblock, &key);
479 r = dm_get_cell(cache->prison, &key, cell_prealloc, cell_result);
481 prealloc_put_cell(structs, cell_prealloc);
486 /*----------------------------------------------------------------*/
488 static bool is_dirty(struct cache *cache, dm_cblock_t b)
490 return test_bit(from_cblock(b), cache->dirty_bitset);
493 static void set_dirty(struct cache *cache, dm_oblock_t oblock, dm_cblock_t cblock)
495 if (!test_and_set_bit(from_cblock(cblock), cache->dirty_bitset)) {
496 cache->nr_dirty = to_cblock(from_cblock(cache->nr_dirty) + 1);
497 policy_set_dirty(cache->policy, oblock);
501 static void clear_dirty(struct cache *cache, dm_oblock_t oblock, dm_cblock_t cblock)
503 if (test_and_clear_bit(from_cblock(cblock), cache->dirty_bitset)) {
504 policy_clear_dirty(cache->policy, oblock);
505 cache->nr_dirty = to_cblock(from_cblock(cache->nr_dirty) - 1);
506 if (!from_cblock(cache->nr_dirty))
507 dm_table_event(cache->ti->table);
511 /*----------------------------------------------------------------*/
513 static bool block_size_is_power_of_two(struct cache *cache)
515 return cache->sectors_per_block_shift >= 0;
518 /* gcc on ARM generates spurious references to __udivdi3 and __umoddi3 */
519 #if defined(CONFIG_ARM) && __GNUC__ == 4 && __GNUC_MINOR__ <= 6
522 static dm_block_t block_div(dm_block_t b, uint32_t n)
529 static dm_dblock_t oblock_to_dblock(struct cache *cache, dm_oblock_t oblock)
531 uint32_t discard_blocks = cache->discard_block_size;
532 dm_block_t b = from_oblock(oblock);
534 if (!block_size_is_power_of_two(cache))
535 discard_blocks = discard_blocks / cache->sectors_per_block;
537 discard_blocks >>= cache->sectors_per_block_shift;
539 b = block_div(b, discard_blocks);
544 static void set_discard(struct cache *cache, dm_dblock_t b)
548 atomic_inc(&cache->stats.discard_count);
550 spin_lock_irqsave(&cache->lock, flags);
551 set_bit(from_dblock(b), cache->discard_bitset);
552 spin_unlock_irqrestore(&cache->lock, flags);
555 static void clear_discard(struct cache *cache, dm_dblock_t b)
559 spin_lock_irqsave(&cache->lock, flags);
560 clear_bit(from_dblock(b), cache->discard_bitset);
561 spin_unlock_irqrestore(&cache->lock, flags);
564 static bool is_discarded(struct cache *cache, dm_dblock_t b)
569 spin_lock_irqsave(&cache->lock, flags);
570 r = test_bit(from_dblock(b), cache->discard_bitset);
571 spin_unlock_irqrestore(&cache->lock, flags);
576 static bool is_discarded_oblock(struct cache *cache, dm_oblock_t b)
581 spin_lock_irqsave(&cache->lock, flags);
582 r = test_bit(from_dblock(oblock_to_dblock(cache, b)),
583 cache->discard_bitset);
584 spin_unlock_irqrestore(&cache->lock, flags);
589 /*----------------------------------------------------------------*/
591 static void load_stats(struct cache *cache)
593 struct dm_cache_statistics stats;
595 dm_cache_metadata_get_stats(cache->cmd, &stats);
596 atomic_set(&cache->stats.read_hit, stats.read_hits);
597 atomic_set(&cache->stats.read_miss, stats.read_misses);
598 atomic_set(&cache->stats.write_hit, stats.write_hits);
599 atomic_set(&cache->stats.write_miss, stats.write_misses);
602 static void save_stats(struct cache *cache)
604 struct dm_cache_statistics stats;
606 stats.read_hits = atomic_read(&cache->stats.read_hit);
607 stats.read_misses = atomic_read(&cache->stats.read_miss);
608 stats.write_hits = atomic_read(&cache->stats.write_hit);
609 stats.write_misses = atomic_read(&cache->stats.write_miss);
611 dm_cache_metadata_set_stats(cache->cmd, &stats);
614 /*----------------------------------------------------------------
616 *--------------------------------------------------------------*/
619 * If using writeback, leave out struct per_bio_data's writethrough fields.
621 #define PB_DATA_SIZE_WB (offsetof(struct per_bio_data, cache))
622 #define PB_DATA_SIZE_WT (sizeof(struct per_bio_data))
624 static bool writethrough_mode(struct cache_features *f)
626 return f->io_mode == CM_IO_WRITETHROUGH;
629 static bool writeback_mode(struct cache_features *f)
631 return f->io_mode == CM_IO_WRITEBACK;
634 static bool passthrough_mode(struct cache_features *f)
636 return f->io_mode == CM_IO_PASSTHROUGH;
639 static size_t get_per_bio_data_size(struct cache *cache)
641 return writethrough_mode(&cache->features) ? PB_DATA_SIZE_WT : PB_DATA_SIZE_WB;
644 static struct per_bio_data *get_per_bio_data(struct bio *bio, size_t data_size)
646 struct per_bio_data *pb = dm_per_bio_data(bio, data_size);
651 static struct per_bio_data *init_per_bio_data(struct bio *bio, size_t data_size)
653 struct per_bio_data *pb = get_per_bio_data(bio, data_size);
656 pb->req_nr = dm_bio_get_target_bio_nr(bio);
657 pb->all_io_entry = NULL;
662 /*----------------------------------------------------------------
664 *--------------------------------------------------------------*/
665 static void remap_to_origin(struct cache *cache, struct bio *bio)
667 bio->bi_bdev = cache->origin_dev->bdev;
670 static void remap_to_cache(struct cache *cache, struct bio *bio,
673 sector_t bi_sector = bio->bi_iter.bi_sector;
674 sector_t block = from_cblock(cblock);
676 bio->bi_bdev = cache->cache_dev->bdev;
677 if (!block_size_is_power_of_two(cache))
678 bio->bi_iter.bi_sector =
679 (block * cache->sectors_per_block) +
680 sector_div(bi_sector, cache->sectors_per_block);
682 bio->bi_iter.bi_sector =
683 (block << cache->sectors_per_block_shift) |
684 (bi_sector & (cache->sectors_per_block - 1));
687 static void check_if_tick_bio_needed(struct cache *cache, struct bio *bio)
690 size_t pb_data_size = get_per_bio_data_size(cache);
691 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
693 spin_lock_irqsave(&cache->lock, flags);
694 if (cache->need_tick_bio &&
695 !(bio->bi_rw & (REQ_FUA | REQ_FLUSH | REQ_DISCARD))) {
697 cache->need_tick_bio = false;
699 spin_unlock_irqrestore(&cache->lock, flags);
702 static void remap_to_origin_clear_discard(struct cache *cache, struct bio *bio,
705 check_if_tick_bio_needed(cache, bio);
706 remap_to_origin(cache, bio);
707 if (bio_data_dir(bio) == WRITE)
708 clear_discard(cache, oblock_to_dblock(cache, oblock));
711 static void remap_to_cache_dirty(struct cache *cache, struct bio *bio,
712 dm_oblock_t oblock, dm_cblock_t cblock)
714 check_if_tick_bio_needed(cache, bio);
715 remap_to_cache(cache, bio, cblock);
716 if (bio_data_dir(bio) == WRITE) {
717 set_dirty(cache, oblock, cblock);
718 clear_discard(cache, oblock_to_dblock(cache, oblock));
722 static dm_oblock_t get_bio_block(struct cache *cache, struct bio *bio)
724 sector_t block_nr = bio->bi_iter.bi_sector;
726 if (!block_size_is_power_of_two(cache))
727 (void) sector_div(block_nr, cache->sectors_per_block);
729 block_nr >>= cache->sectors_per_block_shift;
731 return to_oblock(block_nr);
734 static int bio_triggers_commit(struct cache *cache, struct bio *bio)
736 return bio->bi_rw & (REQ_FLUSH | REQ_FUA);
739 static void issue(struct cache *cache, struct bio *bio)
743 if (!bio_triggers_commit(cache, bio)) {
744 generic_make_request(bio);
749 * Batch together any bios that trigger commits and then issue a
750 * single commit for them in do_worker().
752 spin_lock_irqsave(&cache->lock, flags);
753 cache->commit_requested = true;
754 bio_list_add(&cache->deferred_flush_bios, bio);
755 spin_unlock_irqrestore(&cache->lock, flags);
758 static void defer_writethrough_bio(struct cache *cache, struct bio *bio)
762 spin_lock_irqsave(&cache->lock, flags);
763 bio_list_add(&cache->deferred_writethrough_bios, bio);
764 spin_unlock_irqrestore(&cache->lock, flags);
769 static void writethrough_endio(struct bio *bio, int err)
771 struct per_bio_data *pb = get_per_bio_data(bio, PB_DATA_SIZE_WT);
773 dm_unhook_bio(&pb->hook_info, bio);
780 dm_bio_restore(&pb->bio_details, bio);
781 remap_to_cache(pb->cache, bio, pb->cblock);
784 * We can't issue this bio directly, since we're in interrupt
785 * context. So it gets put on a bio list for processing by the
788 defer_writethrough_bio(pb->cache, bio);
792 * When running in writethrough mode we need to send writes to clean blocks
793 * to both the cache and origin devices. In future we'd like to clone the
794 * bio and send them in parallel, but for now we're doing them in
795 * series as this is easier.
797 static void remap_to_origin_then_cache(struct cache *cache, struct bio *bio,
798 dm_oblock_t oblock, dm_cblock_t cblock)
800 struct per_bio_data *pb = get_per_bio_data(bio, PB_DATA_SIZE_WT);
804 dm_hook_bio(&pb->hook_info, bio, writethrough_endio, NULL);
805 dm_bio_record(&pb->bio_details, bio);
807 remap_to_origin_clear_discard(pb->cache, bio, oblock);
810 /*----------------------------------------------------------------
811 * Migration processing
813 * Migration covers moving data from the origin device to the cache, or
815 *--------------------------------------------------------------*/
816 static void free_migration(struct dm_cache_migration *mg)
818 mempool_free(mg, mg->cache->migration_pool);
821 static void inc_nr_migrations(struct cache *cache)
823 atomic_inc(&cache->nr_migrations);
826 static void dec_nr_migrations(struct cache *cache)
828 atomic_dec(&cache->nr_migrations);
831 * Wake the worker in case we're suspending the target.
833 wake_up(&cache->migration_wait);
836 static void __cell_defer(struct cache *cache, struct dm_bio_prison_cell *cell,
839 (holder ? dm_cell_release : dm_cell_release_no_holder)
840 (cache->prison, cell, &cache->deferred_bios);
841 free_prison_cell(cache, cell);
844 static void cell_defer(struct cache *cache, struct dm_bio_prison_cell *cell,
849 spin_lock_irqsave(&cache->lock, flags);
850 __cell_defer(cache, cell, holder);
851 spin_unlock_irqrestore(&cache->lock, flags);
856 static void cleanup_migration(struct dm_cache_migration *mg)
858 struct cache *cache = mg->cache;
860 dec_nr_migrations(cache);
863 static void migration_failure(struct dm_cache_migration *mg)
865 struct cache *cache = mg->cache;
868 DMWARN_LIMIT("writeback failed; couldn't copy block");
869 set_dirty(cache, mg->old_oblock, mg->cblock);
870 cell_defer(cache, mg->old_ocell, false);
872 } else if (mg->demote) {
873 DMWARN_LIMIT("demotion failed; couldn't copy block");
874 policy_force_mapping(cache->policy, mg->new_oblock, mg->old_oblock);
876 cell_defer(cache, mg->old_ocell, mg->promote ? false : true);
878 cell_defer(cache, mg->new_ocell, true);
880 DMWARN_LIMIT("promotion failed; couldn't copy block");
881 policy_remove_mapping(cache->policy, mg->new_oblock);
882 cell_defer(cache, mg->new_ocell, true);
885 cleanup_migration(mg);
888 static void migration_success_pre_commit(struct dm_cache_migration *mg)
891 struct cache *cache = mg->cache;
894 cell_defer(cache, mg->old_ocell, false);
895 clear_dirty(cache, mg->old_oblock, mg->cblock);
896 cleanup_migration(mg);
899 } else if (mg->demote) {
900 if (dm_cache_remove_mapping(cache->cmd, mg->cblock)) {
901 DMWARN_LIMIT("demotion failed; couldn't update on disk metadata");
902 policy_force_mapping(cache->policy, mg->new_oblock,
905 cell_defer(cache, mg->new_ocell, true);
906 cleanup_migration(mg);
910 if (dm_cache_insert_mapping(cache->cmd, mg->cblock, mg->new_oblock)) {
911 DMWARN_LIMIT("promotion failed; couldn't update on disk metadata");
912 policy_remove_mapping(cache->policy, mg->new_oblock);
913 cleanup_migration(mg);
918 spin_lock_irqsave(&cache->lock, flags);
919 list_add_tail(&mg->list, &cache->need_commit_migrations);
920 cache->commit_requested = true;
921 spin_unlock_irqrestore(&cache->lock, flags);
924 static void migration_success_post_commit(struct dm_cache_migration *mg)
927 struct cache *cache = mg->cache;
930 DMWARN("writeback unexpectedly triggered commit");
933 } else if (mg->demote) {
934 cell_defer(cache, mg->old_ocell, mg->promote ? false : true);
939 spin_lock_irqsave(&cache->lock, flags);
940 list_add_tail(&mg->list, &cache->quiesced_migrations);
941 spin_unlock_irqrestore(&cache->lock, flags);
945 policy_remove_mapping(cache->policy, mg->old_oblock);
946 cleanup_migration(mg);
950 if (mg->requeue_holder)
951 cell_defer(cache, mg->new_ocell, true);
953 bio_endio(mg->new_ocell->holder, 0);
954 cell_defer(cache, mg->new_ocell, false);
956 clear_dirty(cache, mg->new_oblock, mg->cblock);
957 cleanup_migration(mg);
961 static void copy_complete(int read_err, unsigned long write_err, void *context)
964 struct dm_cache_migration *mg = (struct dm_cache_migration *) context;
965 struct cache *cache = mg->cache;
967 if (read_err || write_err)
970 spin_lock_irqsave(&cache->lock, flags);
971 list_add_tail(&mg->list, &cache->completed_migrations);
972 spin_unlock_irqrestore(&cache->lock, flags);
977 static void issue_copy_real(struct dm_cache_migration *mg)
980 struct dm_io_region o_region, c_region;
981 struct cache *cache = mg->cache;
983 o_region.bdev = cache->origin_dev->bdev;
984 o_region.count = cache->sectors_per_block;
986 c_region.bdev = cache->cache_dev->bdev;
987 c_region.sector = from_cblock(mg->cblock) * cache->sectors_per_block;
988 c_region.count = cache->sectors_per_block;
990 if (mg->writeback || mg->demote) {
992 o_region.sector = from_oblock(mg->old_oblock) * cache->sectors_per_block;
993 r = dm_kcopyd_copy(cache->copier, &c_region, 1, &o_region, 0, copy_complete, mg);
996 o_region.sector = from_oblock(mg->new_oblock) * cache->sectors_per_block;
997 r = dm_kcopyd_copy(cache->copier, &o_region, 1, &c_region, 0, copy_complete, mg);
1001 DMERR_LIMIT("issuing migration failed");
1002 migration_failure(mg);
1006 static void overwrite_endio(struct bio *bio, int err)
1008 struct dm_cache_migration *mg = bio->bi_private;
1009 struct cache *cache = mg->cache;
1010 size_t pb_data_size = get_per_bio_data_size(cache);
1011 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
1012 unsigned long flags;
1014 dm_unhook_bio(&pb->hook_info, bio);
1019 mg->requeue_holder = false;
1021 spin_lock_irqsave(&cache->lock, flags);
1022 list_add_tail(&mg->list, &cache->completed_migrations);
1023 spin_unlock_irqrestore(&cache->lock, flags);
1028 static void issue_overwrite(struct dm_cache_migration *mg, struct bio *bio)
1030 size_t pb_data_size = get_per_bio_data_size(mg->cache);
1031 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
1033 dm_hook_bio(&pb->hook_info, bio, overwrite_endio, mg);
1034 remap_to_cache_dirty(mg->cache, bio, mg->new_oblock, mg->cblock);
1035 generic_make_request(bio);
1038 static bool bio_writes_complete_block(struct cache *cache, struct bio *bio)
1040 return (bio_data_dir(bio) == WRITE) &&
1041 (bio->bi_iter.bi_size == (cache->sectors_per_block << SECTOR_SHIFT));
1044 static void avoid_copy(struct dm_cache_migration *mg)
1046 atomic_inc(&mg->cache->stats.copies_avoided);
1047 migration_success_pre_commit(mg);
1050 static void issue_copy(struct dm_cache_migration *mg)
1053 struct cache *cache = mg->cache;
1055 if (mg->writeback || mg->demote)
1056 avoid = !is_dirty(cache, mg->cblock) ||
1057 is_discarded_oblock(cache, mg->old_oblock);
1059 struct bio *bio = mg->new_ocell->holder;
1061 avoid = is_discarded_oblock(cache, mg->new_oblock);
1063 if (!avoid && bio_writes_complete_block(cache, bio)) {
1064 issue_overwrite(mg, bio);
1069 avoid ? avoid_copy(mg) : issue_copy_real(mg);
1072 static void complete_migration(struct dm_cache_migration *mg)
1075 migration_failure(mg);
1077 migration_success_pre_commit(mg);
1080 static void process_migrations(struct cache *cache, struct list_head *head,
1081 void (*fn)(struct dm_cache_migration *))
1083 unsigned long flags;
1084 struct list_head list;
1085 struct dm_cache_migration *mg, *tmp;
1087 INIT_LIST_HEAD(&list);
1088 spin_lock_irqsave(&cache->lock, flags);
1089 list_splice_init(head, &list);
1090 spin_unlock_irqrestore(&cache->lock, flags);
1092 list_for_each_entry_safe(mg, tmp, &list, list)
1096 static void __queue_quiesced_migration(struct dm_cache_migration *mg)
1098 list_add_tail(&mg->list, &mg->cache->quiesced_migrations);
1101 static void queue_quiesced_migration(struct dm_cache_migration *mg)
1103 unsigned long flags;
1104 struct cache *cache = mg->cache;
1106 spin_lock_irqsave(&cache->lock, flags);
1107 __queue_quiesced_migration(mg);
1108 spin_unlock_irqrestore(&cache->lock, flags);
1113 static void queue_quiesced_migrations(struct cache *cache, struct list_head *work)
1115 unsigned long flags;
1116 struct dm_cache_migration *mg, *tmp;
1118 spin_lock_irqsave(&cache->lock, flags);
1119 list_for_each_entry_safe(mg, tmp, work, list)
1120 __queue_quiesced_migration(mg);
1121 spin_unlock_irqrestore(&cache->lock, flags);
1126 static void check_for_quiesced_migrations(struct cache *cache,
1127 struct per_bio_data *pb)
1129 struct list_head work;
1131 if (!pb->all_io_entry)
1134 INIT_LIST_HEAD(&work);
1135 if (pb->all_io_entry)
1136 dm_deferred_entry_dec(pb->all_io_entry, &work);
1138 if (!list_empty(&work))
1139 queue_quiesced_migrations(cache, &work);
1142 static void quiesce_migration(struct dm_cache_migration *mg)
1144 if (!dm_deferred_set_add_work(mg->cache->all_io_ds, &mg->list))
1145 queue_quiesced_migration(mg);
1148 static void promote(struct cache *cache, struct prealloc *structs,
1149 dm_oblock_t oblock, dm_cblock_t cblock,
1150 struct dm_bio_prison_cell *cell)
1152 struct dm_cache_migration *mg = prealloc_get_migration(structs);
1155 mg->writeback = false;
1158 mg->requeue_holder = true;
1159 mg->invalidate = false;
1161 mg->new_oblock = oblock;
1162 mg->cblock = cblock;
1163 mg->old_ocell = NULL;
1164 mg->new_ocell = cell;
1165 mg->start_jiffies = jiffies;
1167 inc_nr_migrations(cache);
1168 quiesce_migration(mg);
1171 static void writeback(struct cache *cache, struct prealloc *structs,
1172 dm_oblock_t oblock, dm_cblock_t cblock,
1173 struct dm_bio_prison_cell *cell)
1175 struct dm_cache_migration *mg = prealloc_get_migration(structs);
1178 mg->writeback = true;
1180 mg->promote = false;
1181 mg->requeue_holder = true;
1182 mg->invalidate = false;
1184 mg->old_oblock = oblock;
1185 mg->cblock = cblock;
1186 mg->old_ocell = cell;
1187 mg->new_ocell = NULL;
1188 mg->start_jiffies = jiffies;
1190 inc_nr_migrations(cache);
1191 quiesce_migration(mg);
1194 static void demote_then_promote(struct cache *cache, struct prealloc *structs,
1195 dm_oblock_t old_oblock, dm_oblock_t new_oblock,
1197 struct dm_bio_prison_cell *old_ocell,
1198 struct dm_bio_prison_cell *new_ocell)
1200 struct dm_cache_migration *mg = prealloc_get_migration(structs);
1203 mg->writeback = false;
1206 mg->requeue_holder = true;
1207 mg->invalidate = false;
1209 mg->old_oblock = old_oblock;
1210 mg->new_oblock = new_oblock;
1211 mg->cblock = cblock;
1212 mg->old_ocell = old_ocell;
1213 mg->new_ocell = new_ocell;
1214 mg->start_jiffies = jiffies;
1216 inc_nr_migrations(cache);
1217 quiesce_migration(mg);
1221 * Invalidate a cache entry. No writeback occurs; any changes in the cache
1222 * block are thrown away.
1224 static void invalidate(struct cache *cache, struct prealloc *structs,
1225 dm_oblock_t oblock, dm_cblock_t cblock,
1226 struct dm_bio_prison_cell *cell)
1228 struct dm_cache_migration *mg = prealloc_get_migration(structs);
1231 mg->writeback = false;
1233 mg->promote = false;
1234 mg->requeue_holder = true;
1235 mg->invalidate = true;
1237 mg->old_oblock = oblock;
1238 mg->cblock = cblock;
1239 mg->old_ocell = cell;
1240 mg->new_ocell = NULL;
1241 mg->start_jiffies = jiffies;
1243 inc_nr_migrations(cache);
1244 quiesce_migration(mg);
1247 /*----------------------------------------------------------------
1249 *--------------------------------------------------------------*/
1250 static void defer_bio(struct cache *cache, struct bio *bio)
1252 unsigned long flags;
1254 spin_lock_irqsave(&cache->lock, flags);
1255 bio_list_add(&cache->deferred_bios, bio);
1256 spin_unlock_irqrestore(&cache->lock, flags);
1261 static void process_flush_bio(struct cache *cache, struct bio *bio)
1263 size_t pb_data_size = get_per_bio_data_size(cache);
1264 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
1266 BUG_ON(bio->bi_iter.bi_size);
1268 remap_to_origin(cache, bio);
1270 remap_to_cache(cache, bio, 0);
1276 * People generally discard large parts of a device, eg, the whole device
1277 * when formatting. Splitting these large discards up into cache block
1278 * sized ios and then quiescing (always neccessary for discard) takes too
1281 * We keep it simple, and allow any size of discard to come in, and just
1282 * mark off blocks on the discard bitset. No passdown occurs!
1284 * To implement passdown we need to change the bio_prison such that a cell
1285 * can have a key that spans many blocks.
1287 static void process_discard_bio(struct cache *cache, struct bio *bio)
1289 dm_block_t start_block = dm_sector_div_up(bio->bi_iter.bi_sector,
1290 cache->discard_block_size);
1291 dm_block_t end_block = bio_end_sector(bio);
1294 end_block = block_div(end_block, cache->discard_block_size);
1296 for (b = start_block; b < end_block; b++)
1297 set_discard(cache, to_dblock(b));
1302 static bool spare_migration_bandwidth(struct cache *cache)
1304 sector_t current_volume = (atomic_read(&cache->nr_migrations) + 1) *
1305 cache->sectors_per_block;
1306 return current_volume < cache->migration_threshold;
1309 static void inc_hit_counter(struct cache *cache, struct bio *bio)
1311 atomic_inc(bio_data_dir(bio) == READ ?
1312 &cache->stats.read_hit : &cache->stats.write_hit);
1315 static void inc_miss_counter(struct cache *cache, struct bio *bio)
1317 atomic_inc(bio_data_dir(bio) == READ ?
1318 &cache->stats.read_miss : &cache->stats.write_miss);
1321 static void issue_cache_bio(struct cache *cache, struct bio *bio,
1322 struct per_bio_data *pb,
1323 dm_oblock_t oblock, dm_cblock_t cblock)
1325 pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
1326 remap_to_cache_dirty(cache, bio, oblock, cblock);
1330 static void process_bio(struct cache *cache, struct prealloc *structs,
1334 bool release_cell = true;
1335 dm_oblock_t block = get_bio_block(cache, bio);
1336 struct dm_bio_prison_cell *cell_prealloc, *old_ocell, *new_ocell;
1337 struct policy_result lookup_result;
1338 size_t pb_data_size = get_per_bio_data_size(cache);
1339 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
1340 bool discarded_block = is_discarded_oblock(cache, block);
1341 bool passthrough = passthrough_mode(&cache->features);
1342 bool can_migrate = !passthrough && (discarded_block || spare_migration_bandwidth(cache));
1345 * Check to see if that block is currently migrating.
1347 cell_prealloc = prealloc_get_cell(structs);
1348 r = bio_detain(cache, block, bio, cell_prealloc,
1349 (cell_free_fn) prealloc_put_cell,
1350 structs, &new_ocell);
1354 r = policy_map(cache->policy, block, true, can_migrate, discarded_block,
1355 bio, &lookup_result);
1357 if (r == -EWOULDBLOCK)
1358 /* migration has been denied */
1359 lookup_result.op = POLICY_MISS;
1361 switch (lookup_result.op) {
1364 inc_miss_counter(cache, bio);
1367 * Passthrough always maps to the origin,
1368 * invalidating any cache blocks that are written
1372 if (bio_data_dir(bio) == WRITE) {
1373 atomic_inc(&cache->stats.demotion);
1374 invalidate(cache, structs, block, lookup_result.cblock, new_ocell);
1375 release_cell = false;
1378 /* FIXME: factor out issue_origin() */
1379 pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
1380 remap_to_origin_clear_discard(cache, bio, block);
1384 inc_hit_counter(cache, bio);
1386 if (bio_data_dir(bio) == WRITE &&
1387 writethrough_mode(&cache->features) &&
1388 !is_dirty(cache, lookup_result.cblock)) {
1389 pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
1390 remap_to_origin_then_cache(cache, bio, block, lookup_result.cblock);
1393 issue_cache_bio(cache, bio, pb, block, lookup_result.cblock);
1399 inc_miss_counter(cache, bio);
1400 pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
1401 remap_to_origin_clear_discard(cache, bio, block);
1406 atomic_inc(&cache->stats.promotion);
1407 promote(cache, structs, block, lookup_result.cblock, new_ocell);
1408 release_cell = false;
1411 case POLICY_REPLACE:
1412 cell_prealloc = prealloc_get_cell(structs);
1413 r = bio_detain(cache, lookup_result.old_oblock, bio, cell_prealloc,
1414 (cell_free_fn) prealloc_put_cell,
1415 structs, &old_ocell);
1418 * We have to be careful to avoid lock inversion of
1419 * the cells. So we back off, and wait for the
1420 * old_ocell to become free.
1422 policy_force_mapping(cache->policy, block,
1423 lookup_result.old_oblock);
1424 atomic_inc(&cache->stats.cache_cell_clash);
1427 atomic_inc(&cache->stats.demotion);
1428 atomic_inc(&cache->stats.promotion);
1430 demote_then_promote(cache, structs, lookup_result.old_oblock,
1431 block, lookup_result.cblock,
1432 old_ocell, new_ocell);
1433 release_cell = false;
1437 DMERR_LIMIT("%s: erroring bio, unknown policy op: %u", __func__,
1438 (unsigned) lookup_result.op);
1443 cell_defer(cache, new_ocell, false);
1446 static int need_commit_due_to_time(struct cache *cache)
1448 return jiffies < cache->last_commit_jiffies ||
1449 jiffies > cache->last_commit_jiffies + COMMIT_PERIOD;
1452 static int commit_if_needed(struct cache *cache)
1456 if ((cache->commit_requested || need_commit_due_to_time(cache)) &&
1457 dm_cache_changed_this_transaction(cache->cmd)) {
1458 atomic_inc(&cache->stats.commit_count);
1459 cache->commit_requested = false;
1460 r = dm_cache_commit(cache->cmd, false);
1461 cache->last_commit_jiffies = jiffies;
1467 static void process_deferred_bios(struct cache *cache)
1469 unsigned long flags;
1470 struct bio_list bios;
1472 struct prealloc structs;
1474 memset(&structs, 0, sizeof(structs));
1475 bio_list_init(&bios);
1477 spin_lock_irqsave(&cache->lock, flags);
1478 bio_list_merge(&bios, &cache->deferred_bios);
1479 bio_list_init(&cache->deferred_bios);
1480 spin_unlock_irqrestore(&cache->lock, flags);
1482 while (!bio_list_empty(&bios)) {
1484 * If we've got no free migration structs, and processing
1485 * this bio might require one, we pause until there are some
1486 * prepared mappings to process.
1488 if (prealloc_data_structs(cache, &structs)) {
1489 spin_lock_irqsave(&cache->lock, flags);
1490 bio_list_merge(&cache->deferred_bios, &bios);
1491 spin_unlock_irqrestore(&cache->lock, flags);
1495 bio = bio_list_pop(&bios);
1497 if (bio->bi_rw & REQ_FLUSH)
1498 process_flush_bio(cache, bio);
1499 else if (bio->bi_rw & REQ_DISCARD)
1500 process_discard_bio(cache, bio);
1502 process_bio(cache, &structs, bio);
1505 prealloc_free_structs(cache, &structs);
1508 static void process_deferred_flush_bios(struct cache *cache, bool submit_bios)
1510 unsigned long flags;
1511 struct bio_list bios;
1514 bio_list_init(&bios);
1516 spin_lock_irqsave(&cache->lock, flags);
1517 bio_list_merge(&bios, &cache->deferred_flush_bios);
1518 bio_list_init(&cache->deferred_flush_bios);
1519 spin_unlock_irqrestore(&cache->lock, flags);
1521 while ((bio = bio_list_pop(&bios)))
1522 submit_bios ? generic_make_request(bio) : bio_io_error(bio);
1525 static void process_deferred_writethrough_bios(struct cache *cache)
1527 unsigned long flags;
1528 struct bio_list bios;
1531 bio_list_init(&bios);
1533 spin_lock_irqsave(&cache->lock, flags);
1534 bio_list_merge(&bios, &cache->deferred_writethrough_bios);
1535 bio_list_init(&cache->deferred_writethrough_bios);
1536 spin_unlock_irqrestore(&cache->lock, flags);
1538 while ((bio = bio_list_pop(&bios)))
1539 generic_make_request(bio);
1542 static void writeback_some_dirty_blocks(struct cache *cache)
1547 struct prealloc structs;
1548 struct dm_bio_prison_cell *old_ocell;
1550 memset(&structs, 0, sizeof(structs));
1552 while (spare_migration_bandwidth(cache)) {
1553 if (prealloc_data_structs(cache, &structs))
1556 r = policy_writeback_work(cache->policy, &oblock, &cblock);
1560 r = get_cell(cache, oblock, &structs, &old_ocell);
1562 policy_set_dirty(cache->policy, oblock);
1566 writeback(cache, &structs, oblock, cblock, old_ocell);
1569 prealloc_free_structs(cache, &structs);
1572 /*----------------------------------------------------------------
1574 * Dropping something from the cache *without* writing back.
1575 *--------------------------------------------------------------*/
1577 static void process_invalidation_request(struct cache *cache, struct invalidation_request *req)
1580 uint64_t begin = from_cblock(req->cblocks->begin);
1581 uint64_t end = from_cblock(req->cblocks->end);
1583 while (begin != end) {
1584 r = policy_remove_cblock(cache->policy, to_cblock(begin));
1586 r = dm_cache_remove_mapping(cache->cmd, to_cblock(begin));
1590 } else if (r == -ENODATA) {
1591 /* harmless, already unmapped */
1595 DMERR("policy_remove_cblock failed");
1602 cache->commit_requested = true;
1605 atomic_set(&req->complete, 1);
1607 wake_up(&req->result_wait);
1610 static void process_invalidation_requests(struct cache *cache)
1612 struct list_head list;
1613 struct invalidation_request *req, *tmp;
1615 INIT_LIST_HEAD(&list);
1616 spin_lock(&cache->invalidation_lock);
1617 list_splice_init(&cache->invalidation_requests, &list);
1618 spin_unlock(&cache->invalidation_lock);
1620 list_for_each_entry_safe (req, tmp, &list, list)
1621 process_invalidation_request(cache, req);
1624 /*----------------------------------------------------------------
1626 *--------------------------------------------------------------*/
1627 static bool is_quiescing(struct cache *cache)
1629 return atomic_read(&cache->quiescing);
1632 static void ack_quiescing(struct cache *cache)
1634 if (is_quiescing(cache)) {
1635 atomic_inc(&cache->quiescing_ack);
1636 wake_up(&cache->quiescing_wait);
1640 static void wait_for_quiescing_ack(struct cache *cache)
1642 wait_event(cache->quiescing_wait, atomic_read(&cache->quiescing_ack));
1645 static void start_quiescing(struct cache *cache)
1647 atomic_inc(&cache->quiescing);
1648 wait_for_quiescing_ack(cache);
1651 static void stop_quiescing(struct cache *cache)
1653 atomic_set(&cache->quiescing, 0);
1654 atomic_set(&cache->quiescing_ack, 0);
1657 static void wait_for_migrations(struct cache *cache)
1659 wait_event(cache->migration_wait, !atomic_read(&cache->nr_migrations));
1662 static void stop_worker(struct cache *cache)
1664 cancel_delayed_work(&cache->waker);
1665 flush_workqueue(cache->wq);
1668 static void requeue_deferred_io(struct cache *cache)
1671 struct bio_list bios;
1673 bio_list_init(&bios);
1674 bio_list_merge(&bios, &cache->deferred_bios);
1675 bio_list_init(&cache->deferred_bios);
1677 while ((bio = bio_list_pop(&bios)))
1678 bio_endio(bio, DM_ENDIO_REQUEUE);
1681 static int more_work(struct cache *cache)
1683 if (is_quiescing(cache))
1684 return !list_empty(&cache->quiesced_migrations) ||
1685 !list_empty(&cache->completed_migrations) ||
1686 !list_empty(&cache->need_commit_migrations);
1688 return !bio_list_empty(&cache->deferred_bios) ||
1689 !bio_list_empty(&cache->deferred_flush_bios) ||
1690 !bio_list_empty(&cache->deferred_writethrough_bios) ||
1691 !list_empty(&cache->quiesced_migrations) ||
1692 !list_empty(&cache->completed_migrations) ||
1693 !list_empty(&cache->need_commit_migrations) ||
1697 static void do_worker(struct work_struct *ws)
1699 struct cache *cache = container_of(ws, struct cache, worker);
1702 if (!is_quiescing(cache)) {
1703 writeback_some_dirty_blocks(cache);
1704 process_deferred_writethrough_bios(cache);
1705 process_deferred_bios(cache);
1706 process_invalidation_requests(cache);
1709 process_migrations(cache, &cache->quiesced_migrations, issue_copy);
1710 process_migrations(cache, &cache->completed_migrations, complete_migration);
1712 if (commit_if_needed(cache)) {
1713 process_deferred_flush_bios(cache, false);
1716 * FIXME: rollback metadata or just go into a
1717 * failure mode and error everything
1720 process_deferred_flush_bios(cache, true);
1721 process_migrations(cache, &cache->need_commit_migrations,
1722 migration_success_post_commit);
1725 ack_quiescing(cache);
1727 } while (more_work(cache));
1731 * We want to commit periodically so that not too much
1732 * unwritten metadata builds up.
1734 static void do_waker(struct work_struct *ws)
1736 struct cache *cache = container_of(to_delayed_work(ws), struct cache, waker);
1737 policy_tick(cache->policy);
1739 queue_delayed_work(cache->wq, &cache->waker, COMMIT_PERIOD);
1742 /*----------------------------------------------------------------*/
1744 static int is_congested(struct dm_dev *dev, int bdi_bits)
1746 struct request_queue *q = bdev_get_queue(dev->bdev);
1747 return bdi_congested(&q->backing_dev_info, bdi_bits);
1750 static int cache_is_congested(struct dm_target_callbacks *cb, int bdi_bits)
1752 struct cache *cache = container_of(cb, struct cache, callbacks);
1754 return is_congested(cache->origin_dev, bdi_bits) ||
1755 is_congested(cache->cache_dev, bdi_bits);
1758 /*----------------------------------------------------------------
1760 *--------------------------------------------------------------*/
1763 * This function gets called on the error paths of the constructor, so we
1764 * have to cope with a partially initialised struct.
1766 static void destroy(struct cache *cache)
1770 if (cache->next_migration)
1771 mempool_free(cache->next_migration, cache->migration_pool);
1773 if (cache->migration_pool)
1774 mempool_destroy(cache->migration_pool);
1776 if (cache->all_io_ds)
1777 dm_deferred_set_destroy(cache->all_io_ds);
1780 dm_bio_prison_destroy(cache->prison);
1783 destroy_workqueue(cache->wq);
1785 if (cache->dirty_bitset)
1786 free_bitset(cache->dirty_bitset);
1788 if (cache->discard_bitset)
1789 free_bitset(cache->discard_bitset);
1792 dm_kcopyd_client_destroy(cache->copier);
1795 dm_cache_metadata_close(cache->cmd);
1797 if (cache->metadata_dev)
1798 dm_put_device(cache->ti, cache->metadata_dev);
1800 if (cache->origin_dev)
1801 dm_put_device(cache->ti, cache->origin_dev);
1803 if (cache->cache_dev)
1804 dm_put_device(cache->ti, cache->cache_dev);
1807 dm_cache_policy_destroy(cache->policy);
1809 for (i = 0; i < cache->nr_ctr_args ; i++)
1810 kfree(cache->ctr_args[i]);
1811 kfree(cache->ctr_args);
1816 static void cache_dtr(struct dm_target *ti)
1818 struct cache *cache = ti->private;
1823 static sector_t get_dev_size(struct dm_dev *dev)
1825 return i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT;
1828 /*----------------------------------------------------------------*/
1831 * Construct a cache device mapping.
1833 * cache <metadata dev> <cache dev> <origin dev> <block size>
1834 * <#feature args> [<feature arg>]*
1835 * <policy> <#policy args> [<policy arg>]*
1837 * metadata dev : fast device holding the persistent metadata
1838 * cache dev : fast device holding cached data blocks
1839 * origin dev : slow device holding original data blocks
1840 * block size : cache unit size in sectors
1842 * #feature args : number of feature arguments passed
1843 * feature args : writethrough. (The default is writeback.)
1845 * policy : the replacement policy to use
1846 * #policy args : an even number of policy arguments corresponding
1847 * to key/value pairs passed to the policy
1848 * policy args : key/value pairs passed to the policy
1849 * E.g. 'sequential_threshold 1024'
1850 * See cache-policies.txt for details.
1852 * Optional feature arguments are:
1853 * writethrough : write through caching that prohibits cache block
1854 * content from being different from origin block content.
1855 * Without this argument, the default behaviour is to write
1856 * back cache block contents later for performance reasons,
1857 * so they may differ from the corresponding origin blocks.
1860 struct dm_target *ti;
1862 struct dm_dev *metadata_dev;
1864 struct dm_dev *cache_dev;
1865 sector_t cache_sectors;
1867 struct dm_dev *origin_dev;
1868 sector_t origin_sectors;
1870 uint32_t block_size;
1872 const char *policy_name;
1874 const char **policy_argv;
1876 struct cache_features features;
1879 static void destroy_cache_args(struct cache_args *ca)
1881 if (ca->metadata_dev)
1882 dm_put_device(ca->ti, ca->metadata_dev);
1885 dm_put_device(ca->ti, ca->cache_dev);
1888 dm_put_device(ca->ti, ca->origin_dev);
1893 static bool at_least_one_arg(struct dm_arg_set *as, char **error)
1896 *error = "Insufficient args";
1903 static int parse_metadata_dev(struct cache_args *ca, struct dm_arg_set *as,
1907 sector_t metadata_dev_size;
1908 char b[BDEVNAME_SIZE];
1910 if (!at_least_one_arg(as, error))
1913 r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
1916 *error = "Error opening metadata device";
1920 metadata_dev_size = get_dev_size(ca->metadata_dev);
1921 if (metadata_dev_size > DM_CACHE_METADATA_MAX_SECTORS_WARNING)
1922 DMWARN("Metadata device %s is larger than %u sectors: excess space will not be used.",
1923 bdevname(ca->metadata_dev->bdev, b), THIN_METADATA_MAX_SECTORS);
1928 static int parse_cache_dev(struct cache_args *ca, struct dm_arg_set *as,
1933 if (!at_least_one_arg(as, error))
1936 r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
1939 *error = "Error opening cache device";
1942 ca->cache_sectors = get_dev_size(ca->cache_dev);
1947 static int parse_origin_dev(struct cache_args *ca, struct dm_arg_set *as,
1952 if (!at_least_one_arg(as, error))
1955 r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
1958 *error = "Error opening origin device";
1962 ca->origin_sectors = get_dev_size(ca->origin_dev);
1963 if (ca->ti->len > ca->origin_sectors) {
1964 *error = "Device size larger than cached device";
1971 static int parse_block_size(struct cache_args *ca, struct dm_arg_set *as,
1974 unsigned long block_size;
1976 if (!at_least_one_arg(as, error))
1979 if (kstrtoul(dm_shift_arg(as), 10, &block_size) || !block_size ||
1980 block_size < DATA_DEV_BLOCK_SIZE_MIN_SECTORS ||
1981 block_size > DATA_DEV_BLOCK_SIZE_MAX_SECTORS ||
1982 block_size & (DATA_DEV_BLOCK_SIZE_MIN_SECTORS - 1)) {
1983 *error = "Invalid data block size";
1987 if (block_size > ca->cache_sectors) {
1988 *error = "Data block size is larger than the cache device";
1992 ca->block_size = block_size;
1997 static void init_features(struct cache_features *cf)
1999 cf->mode = CM_WRITE;
2000 cf->io_mode = CM_IO_WRITEBACK;
2003 static int parse_features(struct cache_args *ca, struct dm_arg_set *as,
2006 static struct dm_arg _args[] = {
2007 {0, 1, "Invalid number of cache feature arguments"},
2013 struct cache_features *cf = &ca->features;
2017 r = dm_read_arg_group(_args, as, &argc, error);
2022 arg = dm_shift_arg(as);
2024 if (!strcasecmp(arg, "writeback"))
2025 cf->io_mode = CM_IO_WRITEBACK;
2027 else if (!strcasecmp(arg, "writethrough"))
2028 cf->io_mode = CM_IO_WRITETHROUGH;
2030 else if (!strcasecmp(arg, "passthrough"))
2031 cf->io_mode = CM_IO_PASSTHROUGH;
2034 *error = "Unrecognised cache feature requested";
2042 static int parse_policy(struct cache_args *ca, struct dm_arg_set *as,
2045 static struct dm_arg _args[] = {
2046 {0, 1024, "Invalid number of policy arguments"},
2051 if (!at_least_one_arg(as, error))
2054 ca->policy_name = dm_shift_arg(as);
2056 r = dm_read_arg_group(_args, as, &ca->policy_argc, error);
2060 ca->policy_argv = (const char **)as->argv;
2061 dm_consume_args(as, ca->policy_argc);
2066 static int parse_cache_args(struct cache_args *ca, int argc, char **argv,
2070 struct dm_arg_set as;
2075 r = parse_metadata_dev(ca, &as, error);
2079 r = parse_cache_dev(ca, &as, error);
2083 r = parse_origin_dev(ca, &as, error);
2087 r = parse_block_size(ca, &as, error);
2091 r = parse_features(ca, &as, error);
2095 r = parse_policy(ca, &as, error);
2102 /*----------------------------------------------------------------*/
2104 static struct kmem_cache *migration_cache;
2106 #define NOT_CORE_OPTION 1
2108 static int process_config_option(struct cache *cache, const char *key, const char *value)
2112 if (!strcasecmp(key, "migration_threshold")) {
2113 if (kstrtoul(value, 10, &tmp))
2116 cache->migration_threshold = tmp;
2120 return NOT_CORE_OPTION;
2123 static int set_config_value(struct cache *cache, const char *key, const char *value)
2125 int r = process_config_option(cache, key, value);
2127 if (r == NOT_CORE_OPTION)
2128 r = policy_set_config_value(cache->policy, key, value);
2131 DMWARN("bad config value for %s: %s", key, value);
2136 static int set_config_values(struct cache *cache, int argc, const char **argv)
2141 DMWARN("Odd number of policy arguments given but they should be <key> <value> pairs.");
2146 r = set_config_value(cache, argv[0], argv[1]);
2157 static int create_cache_policy(struct cache *cache, struct cache_args *ca,
2160 struct dm_cache_policy *p = dm_cache_policy_create(ca->policy_name,
2162 cache->origin_sectors,
2163 cache->sectors_per_block);
2165 *error = "Error creating cache's policy";
2174 * We want the discard block size to be a power of two, at least the size
2175 * of the cache block size, and have no more than 2^14 discard blocks
2176 * across the origin.
2178 #define MAX_DISCARD_BLOCKS (1 << 14)
2180 static bool too_many_discard_blocks(sector_t discard_block_size,
2181 sector_t origin_size)
2183 (void) sector_div(origin_size, discard_block_size);
2185 return origin_size > MAX_DISCARD_BLOCKS;
2188 static sector_t calculate_discard_block_size(sector_t cache_block_size,
2189 sector_t origin_size)
2191 sector_t discard_block_size;
2193 discard_block_size = roundup_pow_of_two(cache_block_size);
2196 while (too_many_discard_blocks(discard_block_size, origin_size))
2197 discard_block_size *= 2;
2199 return discard_block_size;
2202 #define DEFAULT_MIGRATION_THRESHOLD 2048
2204 static int cache_create(struct cache_args *ca, struct cache **result)
2207 char **error = &ca->ti->error;
2208 struct cache *cache;
2209 struct dm_target *ti = ca->ti;
2210 dm_block_t origin_blocks;
2211 struct dm_cache_metadata *cmd;
2212 bool may_format = ca->features.mode == CM_WRITE;
2214 cache = kzalloc(sizeof(*cache), GFP_KERNEL);
2219 ti->private = cache;
2220 ti->num_flush_bios = 2;
2221 ti->flush_supported = true;
2223 ti->num_discard_bios = 1;
2224 ti->discards_supported = true;
2225 ti->discard_zeroes_data_unsupported = true;
2227 cache->features = ca->features;
2228 ti->per_bio_data_size = get_per_bio_data_size(cache);
2230 cache->callbacks.congested_fn = cache_is_congested;
2231 dm_table_add_target_callbacks(ti->table, &cache->callbacks);
2233 cache->metadata_dev = ca->metadata_dev;
2234 cache->origin_dev = ca->origin_dev;
2235 cache->cache_dev = ca->cache_dev;
2237 ca->metadata_dev = ca->origin_dev = ca->cache_dev = NULL;
2239 /* FIXME: factor out this whole section */
2240 origin_blocks = cache->origin_sectors = ca->origin_sectors;
2241 origin_blocks = block_div(origin_blocks, ca->block_size);
2242 cache->origin_blocks = to_oblock(origin_blocks);
2244 cache->sectors_per_block = ca->block_size;
2245 if (dm_set_target_max_io_len(ti, cache->sectors_per_block)) {
2250 if (ca->block_size & (ca->block_size - 1)) {
2251 dm_block_t cache_size = ca->cache_sectors;
2253 cache->sectors_per_block_shift = -1;
2254 cache_size = block_div(cache_size, ca->block_size);
2255 cache->cache_size = to_cblock(cache_size);
2257 cache->sectors_per_block_shift = __ffs(ca->block_size);
2258 cache->cache_size = to_cblock(ca->cache_sectors >> cache->sectors_per_block_shift);
2261 r = create_cache_policy(cache, ca, error);
2265 cache->policy_nr_args = ca->policy_argc;
2266 cache->migration_threshold = DEFAULT_MIGRATION_THRESHOLD;
2268 r = set_config_values(cache, ca->policy_argc, ca->policy_argv);
2270 *error = "Error setting cache policy's config values";
2274 cmd = dm_cache_metadata_open(cache->metadata_dev->bdev,
2275 ca->block_size, may_format,
2276 dm_cache_policy_get_hint_size(cache->policy));
2278 *error = "Error creating metadata object";
2284 if (passthrough_mode(&cache->features)) {
2287 r = dm_cache_metadata_all_clean(cache->cmd, &all_clean);
2289 *error = "dm_cache_metadata_all_clean() failed";
2294 *error = "Cannot enter passthrough mode unless all blocks are clean";
2300 spin_lock_init(&cache->lock);
2301 bio_list_init(&cache->deferred_bios);
2302 bio_list_init(&cache->deferred_flush_bios);
2303 bio_list_init(&cache->deferred_writethrough_bios);
2304 INIT_LIST_HEAD(&cache->quiesced_migrations);
2305 INIT_LIST_HEAD(&cache->completed_migrations);
2306 INIT_LIST_HEAD(&cache->need_commit_migrations);
2307 atomic_set(&cache->nr_migrations, 0);
2308 init_waitqueue_head(&cache->migration_wait);
2310 init_waitqueue_head(&cache->quiescing_wait);
2311 atomic_set(&cache->quiescing, 0);
2312 atomic_set(&cache->quiescing_ack, 0);
2315 cache->nr_dirty = 0;
2316 cache->dirty_bitset = alloc_bitset(from_cblock(cache->cache_size));
2317 if (!cache->dirty_bitset) {
2318 *error = "could not allocate dirty bitset";
2321 clear_bitset(cache->dirty_bitset, from_cblock(cache->cache_size));
2323 cache->discard_block_size =
2324 calculate_discard_block_size(cache->sectors_per_block,
2325 cache->origin_sectors);
2326 cache->discard_nr_blocks = oblock_to_dblock(cache, cache->origin_blocks);
2327 cache->discard_bitset = alloc_bitset(from_dblock(cache->discard_nr_blocks));
2328 if (!cache->discard_bitset) {
2329 *error = "could not allocate discard bitset";
2332 clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks));
2334 cache->copier = dm_kcopyd_client_create(&dm_kcopyd_throttle);
2335 if (IS_ERR(cache->copier)) {
2336 *error = "could not create kcopyd client";
2337 r = PTR_ERR(cache->copier);
2341 cache->wq = alloc_ordered_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM);
2343 *error = "could not create workqueue for metadata object";
2346 INIT_WORK(&cache->worker, do_worker);
2347 INIT_DELAYED_WORK(&cache->waker, do_waker);
2348 cache->last_commit_jiffies = jiffies;
2350 cache->prison = dm_bio_prison_create(PRISON_CELLS);
2351 if (!cache->prison) {
2352 *error = "could not create bio prison";
2356 cache->all_io_ds = dm_deferred_set_create();
2357 if (!cache->all_io_ds) {
2358 *error = "could not create all_io deferred set";
2362 cache->migration_pool = mempool_create_slab_pool(MIGRATION_POOL_SIZE,
2364 if (!cache->migration_pool) {
2365 *error = "Error creating cache's migration mempool";
2369 cache->next_migration = NULL;
2371 cache->need_tick_bio = true;
2372 cache->sized = false;
2373 cache->invalidate = false;
2374 cache->commit_requested = false;
2375 cache->loaded_mappings = false;
2376 cache->loaded_discards = false;
2380 atomic_set(&cache->stats.demotion, 0);
2381 atomic_set(&cache->stats.promotion, 0);
2382 atomic_set(&cache->stats.copies_avoided, 0);
2383 atomic_set(&cache->stats.cache_cell_clash, 0);
2384 atomic_set(&cache->stats.commit_count, 0);
2385 atomic_set(&cache->stats.discard_count, 0);
2387 spin_lock_init(&cache->invalidation_lock);
2388 INIT_LIST_HEAD(&cache->invalidation_requests);
2398 static int copy_ctr_args(struct cache *cache, int argc, const char **argv)
2403 copy = kcalloc(argc, sizeof(*copy), GFP_KERNEL);
2406 for (i = 0; i < argc; i++) {
2407 copy[i] = kstrdup(argv[i], GFP_KERNEL);
2416 cache->nr_ctr_args = argc;
2417 cache->ctr_args = copy;
2422 static int cache_ctr(struct dm_target *ti, unsigned argc, char **argv)
2425 struct cache_args *ca;
2426 struct cache *cache = NULL;
2428 ca = kzalloc(sizeof(*ca), GFP_KERNEL);
2430 ti->error = "Error allocating memory for cache";
2435 r = parse_cache_args(ca, argc, argv, &ti->error);
2439 r = cache_create(ca, &cache);
2443 r = copy_ctr_args(cache, argc - 3, (const char **)argv + 3);
2449 ti->private = cache;
2452 destroy_cache_args(ca);
2456 static int cache_map(struct dm_target *ti, struct bio *bio)
2458 struct cache *cache = ti->private;
2461 dm_oblock_t block = get_bio_block(cache, bio);
2462 size_t pb_data_size = get_per_bio_data_size(cache);
2463 bool can_migrate = false;
2464 bool discarded_block;
2465 struct dm_bio_prison_cell *cell;
2466 struct policy_result lookup_result;
2467 struct per_bio_data *pb;
2469 if (from_oblock(block) > from_oblock(cache->origin_blocks)) {
2471 * This can only occur if the io goes to a partial block at
2472 * the end of the origin device. We don't cache these.
2473 * Just remap to the origin and carry on.
2475 remap_to_origin_clear_discard(cache, bio, block);
2476 return DM_MAPIO_REMAPPED;
2479 pb = init_per_bio_data(bio, pb_data_size);
2481 if (bio->bi_rw & (REQ_FLUSH | REQ_FUA | REQ_DISCARD)) {
2482 defer_bio(cache, bio);
2483 return DM_MAPIO_SUBMITTED;
2487 * Check to see if that block is currently migrating.
2489 cell = alloc_prison_cell(cache);
2491 defer_bio(cache, bio);
2492 return DM_MAPIO_SUBMITTED;
2495 r = bio_detain(cache, block, bio, cell,
2496 (cell_free_fn) free_prison_cell,
2500 defer_bio(cache, bio);
2502 return DM_MAPIO_SUBMITTED;
2505 discarded_block = is_discarded_oblock(cache, block);
2507 r = policy_map(cache->policy, block, false, can_migrate, discarded_block,
2508 bio, &lookup_result);
2509 if (r == -EWOULDBLOCK) {
2510 cell_defer(cache, cell, true);
2511 return DM_MAPIO_SUBMITTED;
2514 DMERR_LIMIT("Unexpected return from cache replacement policy: %d", r);
2516 return DM_MAPIO_SUBMITTED;
2519 r = DM_MAPIO_REMAPPED;
2520 switch (lookup_result.op) {
2522 if (passthrough_mode(&cache->features)) {
2523 if (bio_data_dir(bio) == WRITE) {
2525 * We need to invalidate this block, so
2526 * defer for the worker thread.
2528 cell_defer(cache, cell, true);
2529 r = DM_MAPIO_SUBMITTED;
2532 pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
2533 inc_miss_counter(cache, bio);
2534 remap_to_origin_clear_discard(cache, bio, block);
2536 cell_defer(cache, cell, false);
2540 inc_hit_counter(cache, bio);
2542 if (bio_data_dir(bio) == WRITE && writethrough_mode(&cache->features) &&
2543 !is_dirty(cache, lookup_result.cblock))
2544 remap_to_origin_then_cache(cache, bio, block, lookup_result.cblock);
2546 remap_to_cache_dirty(cache, bio, block, lookup_result.cblock);
2548 cell_defer(cache, cell, false);
2553 inc_miss_counter(cache, bio);
2554 pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
2556 if (pb->req_nr != 0) {
2558 * This is a duplicate writethrough io that is no
2559 * longer needed because the block has been demoted.
2562 cell_defer(cache, cell, false);
2563 return DM_MAPIO_SUBMITTED;
2565 remap_to_origin_clear_discard(cache, bio, block);
2566 cell_defer(cache, cell, false);
2571 DMERR_LIMIT("%s: erroring bio: unknown policy op: %u", __func__,
2572 (unsigned) lookup_result.op);
2574 r = DM_MAPIO_SUBMITTED;
2580 static int cache_end_io(struct dm_target *ti, struct bio *bio, int error)
2582 struct cache *cache = ti->private;
2583 unsigned long flags;
2584 size_t pb_data_size = get_per_bio_data_size(cache);
2585 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
2588 policy_tick(cache->policy);
2590 spin_lock_irqsave(&cache->lock, flags);
2591 cache->need_tick_bio = true;
2592 spin_unlock_irqrestore(&cache->lock, flags);
2595 check_for_quiesced_migrations(cache, pb);
2600 static int write_dirty_bitset(struct cache *cache)
2604 for (i = 0; i < from_cblock(cache->cache_size); i++) {
2605 r = dm_cache_set_dirty(cache->cmd, to_cblock(i),
2606 is_dirty(cache, to_cblock(i)));
2614 static int write_discard_bitset(struct cache *cache)
2618 r = dm_cache_discard_bitset_resize(cache->cmd, cache->discard_block_size,
2619 cache->discard_nr_blocks);
2621 DMERR("could not resize on-disk discard bitset");
2625 for (i = 0; i < from_dblock(cache->discard_nr_blocks); i++) {
2626 r = dm_cache_set_discard(cache->cmd, to_dblock(i),
2627 is_discarded(cache, to_dblock(i)));
2635 static int save_hint(void *context, dm_cblock_t cblock, dm_oblock_t oblock,
2638 struct cache *cache = context;
2639 return dm_cache_save_hint(cache->cmd, cblock, hint);
2642 static int write_hints(struct cache *cache)
2646 r = dm_cache_begin_hints(cache->cmd, cache->policy);
2648 DMERR("dm_cache_begin_hints failed");
2652 r = policy_walk_mappings(cache->policy, save_hint, cache);
2654 DMERR("policy_walk_mappings failed");
2660 * returns true on success
2662 static bool sync_metadata(struct cache *cache)
2666 r1 = write_dirty_bitset(cache);
2668 DMERR("could not write dirty bitset");
2670 r2 = write_discard_bitset(cache);
2672 DMERR("could not write discard bitset");
2676 r3 = write_hints(cache);
2678 DMERR("could not write hints");
2681 * If writing the above metadata failed, we still commit, but don't
2682 * set the clean shutdown flag. This will effectively force every
2683 * dirty bit to be set on reload.
2685 r4 = dm_cache_commit(cache->cmd, !r1 && !r2 && !r3);
2687 DMERR("could not write cache metadata. Data loss may occur.");
2689 return !r1 && !r2 && !r3 && !r4;
2692 static void cache_postsuspend(struct dm_target *ti)
2694 struct cache *cache = ti->private;
2696 start_quiescing(cache);
2697 wait_for_migrations(cache);
2699 requeue_deferred_io(cache);
2700 stop_quiescing(cache);
2702 (void) sync_metadata(cache);
2705 static int load_mapping(void *context, dm_oblock_t oblock, dm_cblock_t cblock,
2706 bool dirty, uint32_t hint, bool hint_valid)
2709 struct cache *cache = context;
2711 r = policy_load_mapping(cache->policy, oblock, cblock, hint, hint_valid);
2716 set_dirty(cache, oblock, cblock);
2718 clear_dirty(cache, oblock, cblock);
2723 static int load_discard(void *context, sector_t discard_block_size,
2724 dm_dblock_t dblock, bool discard)
2726 struct cache *cache = context;
2728 /* FIXME: handle mis-matched block size */
2731 set_discard(cache, dblock);
2733 clear_discard(cache, dblock);
2738 static dm_cblock_t get_cache_dev_size(struct cache *cache)
2740 sector_t size = get_dev_size(cache->cache_dev);
2741 (void) sector_div(size, cache->sectors_per_block);
2742 return to_cblock(size);
2745 static bool can_resize(struct cache *cache, dm_cblock_t new_size)
2747 if (from_cblock(new_size) > from_cblock(cache->cache_size))
2751 * We can't drop a dirty block when shrinking the cache.
2753 while (from_cblock(new_size) < from_cblock(cache->cache_size)) {
2754 new_size = to_cblock(from_cblock(new_size) + 1);
2755 if (is_dirty(cache, new_size)) {
2756 DMERR("unable to shrink cache; cache block %llu is dirty",
2757 (unsigned long long) from_cblock(new_size));
2765 static int resize_cache_dev(struct cache *cache, dm_cblock_t new_size)
2769 r = dm_cache_resize(cache->cmd, new_size);
2771 DMERR("could not resize cache metadata");
2775 cache->cache_size = new_size;
2780 static int cache_preresume(struct dm_target *ti)
2783 struct cache *cache = ti->private;
2784 dm_cblock_t csize = get_cache_dev_size(cache);
2787 * Check to see if the cache has resized.
2789 if (!cache->sized) {
2790 r = resize_cache_dev(cache, csize);
2794 cache->sized = true;
2796 } else if (csize != cache->cache_size) {
2797 if (!can_resize(cache, csize))
2800 r = resize_cache_dev(cache, csize);
2805 if (!cache->loaded_mappings) {
2806 r = dm_cache_load_mappings(cache->cmd, cache->policy,
2807 load_mapping, cache);
2809 DMERR("could not load cache mappings");
2813 cache->loaded_mappings = true;
2816 if (!cache->loaded_discards) {
2817 r = dm_cache_load_discards(cache->cmd, load_discard, cache);
2819 DMERR("could not load origin discards");
2823 cache->loaded_discards = true;
2829 static void cache_resume(struct dm_target *ti)
2831 struct cache *cache = ti->private;
2833 cache->need_tick_bio = true;
2834 do_waker(&cache->waker.work);
2840 * <metadata block size> <#used metadata blocks>/<#total metadata blocks>
2841 * <cache block size> <#used cache blocks>/<#total cache blocks>
2842 * <#read hits> <#read misses> <#write hits> <#write misses>
2843 * <#demotions> <#promotions> <#dirty>
2844 * <#features> <features>*
2845 * <#core args> <core args>
2846 * <policy name> <#policy args> <policy args>*
2848 static void cache_status(struct dm_target *ti, status_type_t type,
2849 unsigned status_flags, char *result, unsigned maxlen)
2854 dm_block_t nr_free_blocks_metadata = 0;
2855 dm_block_t nr_blocks_metadata = 0;
2856 char buf[BDEVNAME_SIZE];
2857 struct cache *cache = ti->private;
2858 dm_cblock_t residency;
2861 case STATUSTYPE_INFO:
2862 /* Commit to ensure statistics aren't out-of-date */
2863 if (!(status_flags & DM_STATUS_NOFLUSH_FLAG) && !dm_suspended(ti)) {
2864 r = dm_cache_commit(cache->cmd, false);
2866 DMERR("could not commit metadata for accurate status");
2869 r = dm_cache_get_free_metadata_block_count(cache->cmd,
2870 &nr_free_blocks_metadata);
2872 DMERR("could not get metadata free block count");
2876 r = dm_cache_get_metadata_dev_size(cache->cmd, &nr_blocks_metadata);
2878 DMERR("could not get metadata device size");
2882 residency = policy_residency(cache->policy);
2884 DMEMIT("%u %llu/%llu %u %llu/%llu %u %u %u %u %u %u %llu ",
2885 (unsigned)(DM_CACHE_METADATA_BLOCK_SIZE >> SECTOR_SHIFT),
2886 (unsigned long long)(nr_blocks_metadata - nr_free_blocks_metadata),
2887 (unsigned long long)nr_blocks_metadata,
2888 cache->sectors_per_block,
2889 (unsigned long long) from_cblock(residency),
2890 (unsigned long long) from_cblock(cache->cache_size),
2891 (unsigned) atomic_read(&cache->stats.read_hit),
2892 (unsigned) atomic_read(&cache->stats.read_miss),
2893 (unsigned) atomic_read(&cache->stats.write_hit),
2894 (unsigned) atomic_read(&cache->stats.write_miss),
2895 (unsigned) atomic_read(&cache->stats.demotion),
2896 (unsigned) atomic_read(&cache->stats.promotion),
2897 (unsigned long long) from_cblock(cache->nr_dirty));
2899 if (writethrough_mode(&cache->features))
2900 DMEMIT("1 writethrough ");
2902 else if (passthrough_mode(&cache->features))
2903 DMEMIT("1 passthrough ");
2905 else if (writeback_mode(&cache->features))
2906 DMEMIT("1 writeback ");
2909 DMERR("internal error: unknown io mode: %d", (int) cache->features.io_mode);
2913 DMEMIT("2 migration_threshold %llu ", (unsigned long long) cache->migration_threshold);
2915 DMEMIT("%s ", dm_cache_policy_get_name(cache->policy));
2917 r = policy_emit_config_values(cache->policy, result + sz, maxlen - sz);
2919 DMERR("policy_emit_config_values returned %d", r);
2924 case STATUSTYPE_TABLE:
2925 format_dev_t(buf, cache->metadata_dev->bdev->bd_dev);
2927 format_dev_t(buf, cache->cache_dev->bdev->bd_dev);
2929 format_dev_t(buf, cache->origin_dev->bdev->bd_dev);
2932 for (i = 0; i < cache->nr_ctr_args - 1; i++)
2933 DMEMIT(" %s", cache->ctr_args[i]);
2934 if (cache->nr_ctr_args)
2935 DMEMIT(" %s", cache->ctr_args[cache->nr_ctr_args - 1]);
2945 * A cache block range can take two forms:
2947 * i) A single cblock, eg. '3456'
2948 * ii) A begin and end cblock with dots between, eg. 123-234
2950 static int parse_cblock_range(struct cache *cache, const char *str,
2951 struct cblock_range *result)
2958 * Try and parse form (ii) first.
2960 r = sscanf(str, "%llu-%llu%c", &b, &e, &dummy);
2965 result->begin = to_cblock(b);
2966 result->end = to_cblock(e);
2971 * That didn't work, try form (i).
2973 r = sscanf(str, "%llu%c", &b, &dummy);
2978 result->begin = to_cblock(b);
2979 result->end = to_cblock(from_cblock(result->begin) + 1u);
2983 DMERR("invalid cblock range '%s'", str);
2987 static int validate_cblock_range(struct cache *cache, struct cblock_range *range)
2989 uint64_t b = from_cblock(range->begin);
2990 uint64_t e = from_cblock(range->end);
2991 uint64_t n = from_cblock(cache->cache_size);
2994 DMERR("begin cblock out of range: %llu >= %llu", b, n);
2999 DMERR("end cblock out of range: %llu > %llu", e, n);
3004 DMERR("invalid cblock range: %llu >= %llu", b, e);
3011 static int request_invalidation(struct cache *cache, struct cblock_range *range)
3013 struct invalidation_request req;
3015 INIT_LIST_HEAD(&req.list);
3016 req.cblocks = range;
3017 atomic_set(&req.complete, 0);
3019 init_waitqueue_head(&req.result_wait);
3021 spin_lock(&cache->invalidation_lock);
3022 list_add(&req.list, &cache->invalidation_requests);
3023 spin_unlock(&cache->invalidation_lock);
3026 wait_event(req.result_wait, atomic_read(&req.complete));
3030 static int process_invalidate_cblocks_message(struct cache *cache, unsigned count,
3031 const char **cblock_ranges)
3035 struct cblock_range range;
3037 if (!passthrough_mode(&cache->features)) {
3038 DMERR("cache has to be in passthrough mode for invalidation");
3042 for (i = 0; i < count; i++) {
3043 r = parse_cblock_range(cache, cblock_ranges[i], &range);
3047 r = validate_cblock_range(cache, &range);
3052 * Pass begin and end origin blocks to the worker and wake it.
3054 r = request_invalidation(cache, &range);
3066 * "invalidate_cblocks [(<begin>)|(<begin>-<end>)]*
3068 * The key migration_threshold is supported by the cache target core.
3070 static int cache_message(struct dm_target *ti, unsigned argc, char **argv)
3072 struct cache *cache = ti->private;
3077 if (!strcasecmp(argv[0], "invalidate_cblocks"))
3078 return process_invalidate_cblocks_message(cache, argc - 1, (const char **) argv + 1);
3083 return set_config_value(cache, argv[0], argv[1]);
3086 static int cache_iterate_devices(struct dm_target *ti,
3087 iterate_devices_callout_fn fn, void *data)
3090 struct cache *cache = ti->private;
3092 r = fn(ti, cache->cache_dev, 0, get_dev_size(cache->cache_dev), data);
3094 r = fn(ti, cache->origin_dev, 0, ti->len, data);
3100 * We assume I/O is going to the origin (which is the volume
3101 * more likely to have restrictions e.g. by being striped).
3102 * (Looking up the exact location of the data would be expensive
3103 * and could always be out of date by the time the bio is submitted.)
3105 static int cache_bvec_merge(struct dm_target *ti,
3106 struct bvec_merge_data *bvm,
3107 struct bio_vec *biovec, int max_size)
3109 struct cache *cache = ti->private;
3110 struct request_queue *q = bdev_get_queue(cache->origin_dev->bdev);
3112 if (!q->merge_bvec_fn)
3115 bvm->bi_bdev = cache->origin_dev->bdev;
3116 return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
3119 static void set_discard_limits(struct cache *cache, struct queue_limits *limits)
3122 * FIXME: these limits may be incompatible with the cache device
3124 limits->max_discard_sectors = cache->discard_block_size * 1024;
3125 limits->discard_granularity = cache->discard_block_size << SECTOR_SHIFT;
3128 static void cache_io_hints(struct dm_target *ti, struct queue_limits *limits)
3130 struct cache *cache = ti->private;
3131 uint64_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;
3134 * If the system-determined stacked limits are compatible with the
3135 * cache's blocksize (io_opt is a factor) do not override them.
3137 if (io_opt_sectors < cache->sectors_per_block ||
3138 do_div(io_opt_sectors, cache->sectors_per_block)) {
3139 blk_limits_io_min(limits, 0);
3140 blk_limits_io_opt(limits, cache->sectors_per_block << SECTOR_SHIFT);
3142 set_discard_limits(cache, limits);
3145 /*----------------------------------------------------------------*/
3147 static struct target_type cache_target = {
3149 .version = {1, 3, 0},
3150 .module = THIS_MODULE,
3154 .end_io = cache_end_io,
3155 .postsuspend = cache_postsuspend,
3156 .preresume = cache_preresume,
3157 .resume = cache_resume,
3158 .status = cache_status,
3159 .message = cache_message,
3160 .iterate_devices = cache_iterate_devices,
3161 .merge = cache_bvec_merge,
3162 .io_hints = cache_io_hints,
3165 static int __init dm_cache_init(void)
3169 r = dm_register_target(&cache_target);
3171 DMERR("cache target registration failed: %d", r);
3175 migration_cache = KMEM_CACHE(dm_cache_migration, 0);
3176 if (!migration_cache) {
3177 dm_unregister_target(&cache_target);
3184 static void __exit dm_cache_exit(void)
3186 dm_unregister_target(&cache_target);
3187 kmem_cache_destroy(migration_cache);
3190 module_init(dm_cache_init);
3191 module_exit(dm_cache_exit);
3193 MODULE_DESCRIPTION(DM_NAME " cache target");
3194 MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
3195 MODULE_LICENSE("GPL");