2 * Copyright (C) 2012 Red Hat. All rights reserved.
4 * This file is released under the GPL.
8 #include "dm-bio-prison-v2.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/jiffies.h>
15 #include <linux/init.h>
16 #include <linux/mempool.h>
17 #include <linux/module.h>
18 #include <linux/rwsem.h>
19 #include <linux/slab.h>
20 #include <linux/vmalloc.h>
22 #define DM_MSG_PREFIX "cache"
24 DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(cache_copy_throttle
,
25 "A percentage of time allocated for copying to and/or from cache");
27 /*----------------------------------------------------------------*/
32 * oblock: index of an origin block
33 * cblock: index of a cache block
34 * promotion: movement of a block from origin to cache
35 * demotion: movement of a block from cache to origin
36 * migration: movement of a block between the origin and cache device,
40 /*----------------------------------------------------------------*/
46 * Sectors of in-flight IO.
51 * The time, in jiffies, when this device became idle (if it is
54 unsigned long idle_time
;
55 unsigned long last_update_time
;
58 static void iot_init(struct io_tracker
*iot
)
60 spin_lock_init(&iot
->lock
);
63 iot
->last_update_time
= jiffies
;
66 static bool __iot_idle_for(struct io_tracker
*iot
, unsigned long jifs
)
71 return time_after(jiffies
, iot
->idle_time
+ jifs
);
74 static bool iot_idle_for(struct io_tracker
*iot
, unsigned long jifs
)
79 spin_lock_irqsave(&iot
->lock
, flags
);
80 r
= __iot_idle_for(iot
, jifs
);
81 spin_unlock_irqrestore(&iot
->lock
, flags
);
86 static void iot_io_begin(struct io_tracker
*iot
, sector_t len
)
90 spin_lock_irqsave(&iot
->lock
, flags
);
91 iot
->in_flight
+= len
;
92 spin_unlock_irqrestore(&iot
->lock
, flags
);
95 static void __iot_io_end(struct io_tracker
*iot
, sector_t len
)
97 iot
->in_flight
-= len
;
99 iot
->idle_time
= jiffies
;
102 static void iot_io_end(struct io_tracker
*iot
, sector_t len
)
106 spin_lock_irqsave(&iot
->lock
, flags
);
107 __iot_io_end(iot
, len
);
108 spin_unlock_irqrestore(&iot
->lock
, flags
);
111 /*----------------------------------------------------------------*/
114 * Represents a chunk of future work. 'input' allows continuations to pass
115 * values between themselves, typically error values.
117 struct continuation
{
118 struct work_struct ws
;
122 static inline void init_continuation(struct continuation
*k
,
123 void (*fn
)(struct work_struct
*))
125 INIT_WORK(&k
->ws
, fn
);
129 static inline void queue_continuation(struct workqueue_struct
*wq
,
130 struct continuation
*k
)
132 queue_work(wq
, &k
->ws
);
135 /*----------------------------------------------------------------*/
138 * The batcher collects together pieces of work that need a particular
139 * operation to occur before they can proceed (typically a commit).
143 * The operation that everyone is waiting for.
145 int (*commit_op
)(void *context
);
146 void *commit_context
;
149 * This is how bios should be issued once the commit op is complete
150 * (accounted_request).
152 void (*issue_op
)(struct bio
*bio
, void *context
);
156 * Queued work gets put on here after commit.
158 struct workqueue_struct
*wq
;
161 struct list_head work_items
;
162 struct bio_list bios
;
163 struct work_struct commit_work
;
165 bool commit_scheduled
;
168 static void __commit(struct work_struct
*_ws
)
170 struct batcher
*b
= container_of(_ws
, struct batcher
, commit_work
);
174 struct list_head work_items
;
175 struct work_struct
*ws
, *tmp
;
176 struct continuation
*k
;
178 struct bio_list bios
;
180 INIT_LIST_HEAD(&work_items
);
181 bio_list_init(&bios
);
184 * We have to grab these before the commit_op to avoid a race
187 spin_lock_irqsave(&b
->lock
, flags
);
188 list_splice_init(&b
->work_items
, &work_items
);
189 bio_list_merge(&bios
, &b
->bios
);
190 bio_list_init(&b
->bios
);
191 b
->commit_scheduled
= false;
192 spin_unlock_irqrestore(&b
->lock
, flags
);
194 r
= b
->commit_op(b
->commit_context
);
196 list_for_each_entry_safe(ws
, tmp
, &work_items
, entry
) {
197 k
= container_of(ws
, struct continuation
, ws
);
199 INIT_LIST_HEAD(&ws
->entry
); /* to avoid a WARN_ON */
200 queue_work(b
->wq
, ws
);
203 while ((bio
= bio_list_pop(&bios
))) {
208 b
->issue_op(bio
, b
->issue_context
);
212 static void batcher_init(struct batcher
*b
,
213 int (*commit_op
)(void *),
214 void *commit_context
,
215 void (*issue_op
)(struct bio
*bio
, void *),
217 struct workqueue_struct
*wq
)
219 b
->commit_op
= commit_op
;
220 b
->commit_context
= commit_context
;
221 b
->issue_op
= issue_op
;
222 b
->issue_context
= issue_context
;
225 spin_lock_init(&b
->lock
);
226 INIT_LIST_HEAD(&b
->work_items
);
227 bio_list_init(&b
->bios
);
228 INIT_WORK(&b
->commit_work
, __commit
);
229 b
->commit_scheduled
= false;
232 static void async_commit(struct batcher
*b
)
234 queue_work(b
->wq
, &b
->commit_work
);
237 static void continue_after_commit(struct batcher
*b
, struct continuation
*k
)
240 bool commit_scheduled
;
242 spin_lock_irqsave(&b
->lock
, flags
);
243 commit_scheduled
= b
->commit_scheduled
;
244 list_add_tail(&k
->ws
.entry
, &b
->work_items
);
245 spin_unlock_irqrestore(&b
->lock
, flags
);
247 if (commit_scheduled
)
252 * Bios are errored if commit failed.
254 static void issue_after_commit(struct batcher
*b
, struct bio
*bio
)
257 bool commit_scheduled
;
259 spin_lock_irqsave(&b
->lock
, flags
);
260 commit_scheduled
= b
->commit_scheduled
;
261 bio_list_add(&b
->bios
, bio
);
262 spin_unlock_irqrestore(&b
->lock
, flags
);
264 if (commit_scheduled
)
269 * Call this if some urgent work is waiting for the commit to complete.
271 static void schedule_commit(struct batcher
*b
)
276 spin_lock_irqsave(&b
->lock
, flags
);
277 immediate
= !list_empty(&b
->work_items
) || !bio_list_empty(&b
->bios
);
278 b
->commit_scheduled
= true;
279 spin_unlock_irqrestore(&b
->lock
, flags
);
286 * There are a couple of places where we let a bio run, but want to do some
287 * work before calling its endio function. We do this by temporarily
288 * changing the endio fn.
290 struct dm_hook_info
{
291 bio_end_io_t
*bi_end_io
;
294 static void dm_hook_bio(struct dm_hook_info
*h
, struct bio
*bio
,
295 bio_end_io_t
*bi_end_io
, void *bi_private
)
297 h
->bi_end_io
= bio
->bi_end_io
;
299 bio
->bi_end_io
= bi_end_io
;
300 bio
->bi_private
= bi_private
;
303 static void dm_unhook_bio(struct dm_hook_info
*h
, struct bio
*bio
)
305 bio
->bi_end_io
= h
->bi_end_io
;
308 /*----------------------------------------------------------------*/
310 #define MIGRATION_POOL_SIZE 128
311 #define COMMIT_PERIOD HZ
312 #define MIGRATION_COUNT_WINDOW 10
315 * The block size of the device holding cache data must be
316 * between 32KB and 1GB.
318 #define DATA_DEV_BLOCK_SIZE_MIN_SECTORS (32 * 1024 >> SECTOR_SHIFT)
319 #define DATA_DEV_BLOCK_SIZE_MAX_SECTORS (1024 * 1024 * 1024 >> SECTOR_SHIFT)
321 enum cache_metadata_mode
{
322 CM_WRITE
, /* metadata may be changed */
323 CM_READ_ONLY
, /* metadata may not be changed */
329 * Data is written to cached blocks only. These blocks are marked
330 * dirty. If you lose the cache device you will lose data.
331 * Potential performance increase for both reads and writes.
336 * Data is written to both cache and origin. Blocks are never
337 * dirty. Potential performance benfit for reads only.
342 * A degraded mode useful for various cache coherency situations
343 * (eg, rolling back snapshots). Reads and writes always go to the
344 * origin. If a write goes to a cached oblock, then the cache
345 * block is invalidated.
350 struct cache_features
{
351 enum cache_metadata_mode mode
;
352 enum cache_io_mode io_mode
;
353 unsigned metadata_version
;
364 atomic_t copies_avoided
;
365 atomic_t cache_cell_clash
;
366 atomic_t commit_count
;
367 atomic_t discard_count
;
371 struct dm_target
*ti
;
372 struct dm_target_callbacks callbacks
;
374 struct dm_cache_metadata
*cmd
;
377 * Metadata is written to this device.
379 struct dm_dev
*metadata_dev
;
382 * The slower of the two data devices. Typically a spindle.
384 struct dm_dev
*origin_dev
;
387 * The faster of the two data devices. Typically an SSD.
389 struct dm_dev
*cache_dev
;
392 * Size of the origin device in _complete_ blocks and native sectors.
394 dm_oblock_t origin_blocks
;
395 sector_t origin_sectors
;
398 * Size of the cache device in blocks.
400 dm_cblock_t cache_size
;
403 * Fields for converting from sectors to blocks.
405 sector_t sectors_per_block
;
406 int sectors_per_block_shift
;
409 struct list_head deferred_cells
;
410 struct bio_list deferred_bios
;
411 struct bio_list deferred_writethrough_bios
;
412 sector_t migration_threshold
;
413 wait_queue_head_t migration_wait
;
414 atomic_t nr_allocated_migrations
;
417 * The number of in flight migrations that are performing
418 * background io. eg, promotion, writeback.
420 atomic_t nr_io_migrations
;
422 struct rw_semaphore quiesce_lock
;
425 * cache_size entries, dirty if set
428 unsigned long *dirty_bitset
;
431 * origin_blocks entries, discarded if set.
433 dm_dblock_t discard_nr_blocks
;
434 unsigned long *discard_bitset
;
435 uint32_t discard_block_size
; /* a power of 2 times sectors per block */
438 * Rather than reconstructing the table line for the status we just
439 * save it and regurgitate.
441 unsigned nr_ctr_args
;
442 const char **ctr_args
;
444 struct dm_kcopyd_client
*copier
;
445 struct workqueue_struct
*wq
;
446 struct work_struct deferred_bio_worker
;
447 struct work_struct deferred_writethrough_worker
;
448 struct work_struct migration_worker
;
449 struct delayed_work waker
;
450 struct dm_bio_prison_v2
*prison
;
452 mempool_t
*migration_pool
;
454 struct dm_cache_policy
*policy
;
455 unsigned policy_nr_args
;
457 bool need_tick_bio
:1;
460 bool commit_requested
:1;
461 bool loaded_mappings
:1;
462 bool loaded_discards
:1;
465 * Cache features such as write-through.
467 struct cache_features features
;
469 struct cache_stats stats
;
472 * Invalidation fields.
474 spinlock_t invalidation_lock
;
475 struct list_head invalidation_requests
;
477 struct io_tracker origin_tracker
;
479 struct work_struct commit_ws
;
480 struct batcher committer
;
482 struct rw_semaphore background_work_lock
;
485 struct per_bio_data
{
488 struct dm_bio_prison_cell_v2
*cell
;
489 struct dm_hook_info hook_info
;
493 * writethrough fields. These MUST remain at the end of this
494 * structure and the 'cache' member must be the first as it
495 * is used to determine the offset of the writethrough fields.
499 struct dm_bio_details bio_details
;
502 struct dm_cache_migration
{
503 struct continuation k
;
506 struct policy_work
*op
;
507 struct bio
*overwrite_bio
;
508 struct dm_bio_prison_cell_v2
*cell
;
510 dm_cblock_t invalidate_cblock
;
511 dm_oblock_t invalidate_oblock
;
514 /*----------------------------------------------------------------*/
516 static bool writethrough_mode(struct cache_features
*f
)
518 return f
->io_mode
== CM_IO_WRITETHROUGH
;
521 static bool writeback_mode(struct cache_features
*f
)
523 return f
->io_mode
== CM_IO_WRITEBACK
;
526 static inline bool passthrough_mode(struct cache_features
*f
)
528 return unlikely(f
->io_mode
== CM_IO_PASSTHROUGH
);
531 /*----------------------------------------------------------------*/
533 static void wake_deferred_bio_worker(struct cache
*cache
)
535 queue_work(cache
->wq
, &cache
->deferred_bio_worker
);
538 static void wake_deferred_writethrough_worker(struct cache
*cache
)
540 queue_work(cache
->wq
, &cache
->deferred_writethrough_worker
);
543 static void wake_migration_worker(struct cache
*cache
)
545 if (passthrough_mode(&cache
->features
))
548 queue_work(cache
->wq
, &cache
->migration_worker
);
551 /*----------------------------------------------------------------*/
553 static struct dm_bio_prison_cell_v2
*alloc_prison_cell(struct cache
*cache
)
555 return dm_bio_prison_alloc_cell_v2(cache
->prison
, GFP_NOWAIT
);
558 static void free_prison_cell(struct cache
*cache
, struct dm_bio_prison_cell_v2
*cell
)
560 dm_bio_prison_free_cell_v2(cache
->prison
, cell
);
563 static struct dm_cache_migration
*alloc_migration(struct cache
*cache
)
565 struct dm_cache_migration
*mg
;
567 mg
= mempool_alloc(cache
->migration_pool
, GFP_NOWAIT
);
570 atomic_inc(&mg
->cache
->nr_allocated_migrations
);
576 static void free_migration(struct dm_cache_migration
*mg
)
578 struct cache
*cache
= mg
->cache
;
580 if (atomic_dec_and_test(&cache
->nr_allocated_migrations
))
581 wake_up(&cache
->migration_wait
);
583 mempool_free(mg
, cache
->migration_pool
);
586 /*----------------------------------------------------------------*/
588 static inline dm_oblock_t
oblock_succ(dm_oblock_t b
)
590 return to_oblock(from_oblock(b
) + 1ull);
593 static void build_key(dm_oblock_t begin
, dm_oblock_t end
, struct dm_cell_key_v2
*key
)
597 key
->block_begin
= from_oblock(begin
);
598 key
->block_end
= from_oblock(end
);
602 * We have two lock levels. Level 0, which is used to prevent WRITEs, and
603 * level 1 which prevents *both* READs and WRITEs.
605 #define WRITE_LOCK_LEVEL 0
606 #define READ_WRITE_LOCK_LEVEL 1
608 static unsigned lock_level(struct bio
*bio
)
610 return bio_data_dir(bio
) == WRITE
?
612 READ_WRITE_LOCK_LEVEL
;
615 /*----------------------------------------------------------------
617 *--------------------------------------------------------------*/
620 * If using writeback, leave out struct per_bio_data's writethrough fields.
622 #define PB_DATA_SIZE_WB (offsetof(struct per_bio_data, cache))
623 #define PB_DATA_SIZE_WT (sizeof(struct per_bio_data))
625 static size_t get_per_bio_data_size(struct cache
*cache
)
627 return writethrough_mode(&cache
->features
) ? PB_DATA_SIZE_WT
: PB_DATA_SIZE_WB
;
630 static struct per_bio_data
*get_per_bio_data(struct bio
*bio
, size_t data_size
)
632 struct per_bio_data
*pb
= dm_per_bio_data(bio
, data_size
);
637 static struct per_bio_data
*init_per_bio_data(struct bio
*bio
, size_t data_size
)
639 struct per_bio_data
*pb
= get_per_bio_data(bio
, data_size
);
642 pb
->req_nr
= dm_bio_get_target_bio_nr(bio
);
649 /*----------------------------------------------------------------*/
651 static void defer_bio(struct cache
*cache
, struct bio
*bio
)
655 spin_lock_irqsave(&cache
->lock
, flags
);
656 bio_list_add(&cache
->deferred_bios
, bio
);
657 spin_unlock_irqrestore(&cache
->lock
, flags
);
659 wake_deferred_bio_worker(cache
);
662 static void defer_bios(struct cache
*cache
, struct bio_list
*bios
)
666 spin_lock_irqsave(&cache
->lock
, flags
);
667 bio_list_merge(&cache
->deferred_bios
, bios
);
669 spin_unlock_irqrestore(&cache
->lock
, flags
);
671 wake_deferred_bio_worker(cache
);
674 /*----------------------------------------------------------------*/
676 static bool bio_detain_shared(struct cache
*cache
, dm_oblock_t oblock
, struct bio
*bio
)
680 struct per_bio_data
*pb
;
681 struct dm_cell_key_v2 key
;
682 dm_oblock_t end
= to_oblock(from_oblock(oblock
) + 1ULL);
683 struct dm_bio_prison_cell_v2
*cell_prealloc
, *cell
;
685 cell_prealloc
= alloc_prison_cell(cache
); /* FIXME: allow wait if calling from worker */
686 if (!cell_prealloc
) {
687 defer_bio(cache
, bio
);
691 build_key(oblock
, end
, &key
);
692 r
= dm_cell_get_v2(cache
->prison
, &key
, lock_level(bio
), bio
, cell_prealloc
, &cell
);
695 * Failed to get the lock.
697 free_prison_cell(cache
, cell_prealloc
);
701 if (cell
!= cell_prealloc
)
702 free_prison_cell(cache
, cell_prealloc
);
704 pb_size
= get_per_bio_data_size(cache
);
705 pb
= get_per_bio_data(bio
, pb_size
);
711 /*----------------------------------------------------------------*/
713 static bool is_dirty(struct cache
*cache
, dm_cblock_t b
)
715 return test_bit(from_cblock(b
), cache
->dirty_bitset
);
718 static void set_dirty(struct cache
*cache
, dm_cblock_t cblock
)
720 if (!test_and_set_bit(from_cblock(cblock
), cache
->dirty_bitset
)) {
721 atomic_inc(&cache
->nr_dirty
);
722 policy_set_dirty(cache
->policy
, cblock
);
727 * These two are called when setting after migrations to force the policy
728 * and dirty bitset to be in sync.
730 static void force_set_dirty(struct cache
*cache
, dm_cblock_t cblock
)
732 if (!test_and_set_bit(from_cblock(cblock
), cache
->dirty_bitset
))
733 atomic_inc(&cache
->nr_dirty
);
734 policy_set_dirty(cache
->policy
, cblock
);
737 static void force_clear_dirty(struct cache
*cache
, dm_cblock_t cblock
)
739 if (test_and_clear_bit(from_cblock(cblock
), cache
->dirty_bitset
)) {
740 if (atomic_dec_return(&cache
->nr_dirty
) == 0)
741 dm_table_event(cache
->ti
->table
);
744 policy_clear_dirty(cache
->policy
, cblock
);
747 /*----------------------------------------------------------------*/
749 static bool block_size_is_power_of_two(struct cache
*cache
)
751 return cache
->sectors_per_block_shift
>= 0;
754 /* gcc on ARM generates spurious references to __udivdi3 and __umoddi3 */
755 #if defined(CONFIG_ARM) && __GNUC__ == 4 && __GNUC_MINOR__ <= 6
758 static dm_block_t
block_div(dm_block_t b
, uint32_t n
)
765 static dm_block_t
oblocks_per_dblock(struct cache
*cache
)
767 dm_block_t oblocks
= cache
->discard_block_size
;
769 if (block_size_is_power_of_two(cache
))
770 oblocks
>>= cache
->sectors_per_block_shift
;
772 oblocks
= block_div(oblocks
, cache
->sectors_per_block
);
777 static dm_dblock_t
oblock_to_dblock(struct cache
*cache
, dm_oblock_t oblock
)
779 return to_dblock(block_div(from_oblock(oblock
),
780 oblocks_per_dblock(cache
)));
783 static void set_discard(struct cache
*cache
, dm_dblock_t b
)
787 BUG_ON(from_dblock(b
) >= from_dblock(cache
->discard_nr_blocks
));
788 atomic_inc(&cache
->stats
.discard_count
);
790 spin_lock_irqsave(&cache
->lock
, flags
);
791 set_bit(from_dblock(b
), cache
->discard_bitset
);
792 spin_unlock_irqrestore(&cache
->lock
, flags
);
795 static void clear_discard(struct cache
*cache
, dm_dblock_t b
)
799 spin_lock_irqsave(&cache
->lock
, flags
);
800 clear_bit(from_dblock(b
), cache
->discard_bitset
);
801 spin_unlock_irqrestore(&cache
->lock
, flags
);
804 static bool is_discarded(struct cache
*cache
, dm_dblock_t b
)
809 spin_lock_irqsave(&cache
->lock
, flags
);
810 r
= test_bit(from_dblock(b
), cache
->discard_bitset
);
811 spin_unlock_irqrestore(&cache
->lock
, flags
);
816 static bool is_discarded_oblock(struct cache
*cache
, dm_oblock_t b
)
821 spin_lock_irqsave(&cache
->lock
, flags
);
822 r
= test_bit(from_dblock(oblock_to_dblock(cache
, b
)),
823 cache
->discard_bitset
);
824 spin_unlock_irqrestore(&cache
->lock
, flags
);
829 /*----------------------------------------------------------------
831 *--------------------------------------------------------------*/
832 static void remap_to_origin(struct cache
*cache
, struct bio
*bio
)
834 bio
->bi_bdev
= cache
->origin_dev
->bdev
;
837 static void remap_to_cache(struct cache
*cache
, struct bio
*bio
,
840 sector_t bi_sector
= bio
->bi_iter
.bi_sector
;
841 sector_t block
= from_cblock(cblock
);
843 bio
->bi_bdev
= cache
->cache_dev
->bdev
;
844 if (!block_size_is_power_of_two(cache
))
845 bio
->bi_iter
.bi_sector
=
846 (block
* cache
->sectors_per_block
) +
847 sector_div(bi_sector
, cache
->sectors_per_block
);
849 bio
->bi_iter
.bi_sector
=
850 (block
<< cache
->sectors_per_block_shift
) |
851 (bi_sector
& (cache
->sectors_per_block
- 1));
854 static void check_if_tick_bio_needed(struct cache
*cache
, struct bio
*bio
)
857 size_t pb_data_size
= get_per_bio_data_size(cache
);
858 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
860 spin_lock_irqsave(&cache
->lock
, flags
);
861 if (cache
->need_tick_bio
&& !op_is_flush(bio
->bi_opf
) &&
862 bio_op(bio
) != REQ_OP_DISCARD
) {
864 cache
->need_tick_bio
= false;
866 spin_unlock_irqrestore(&cache
->lock
, flags
);
869 static void remap_to_origin_clear_discard(struct cache
*cache
, struct bio
*bio
,
872 // FIXME: this is called way too much.
873 check_if_tick_bio_needed(cache
, bio
);
874 remap_to_origin(cache
, bio
);
875 if (bio_data_dir(bio
) == WRITE
)
876 clear_discard(cache
, oblock_to_dblock(cache
, oblock
));
879 static void remap_to_cache_dirty(struct cache
*cache
, struct bio
*bio
,
880 dm_oblock_t oblock
, dm_cblock_t cblock
)
882 check_if_tick_bio_needed(cache
, bio
);
883 remap_to_cache(cache
, bio
, cblock
);
884 if (bio_data_dir(bio
) == WRITE
) {
885 set_dirty(cache
, cblock
);
886 clear_discard(cache
, oblock_to_dblock(cache
, oblock
));
890 static dm_oblock_t
get_bio_block(struct cache
*cache
, struct bio
*bio
)
892 sector_t block_nr
= bio
->bi_iter
.bi_sector
;
894 if (!block_size_is_power_of_two(cache
))
895 (void) sector_div(block_nr
, cache
->sectors_per_block
);
897 block_nr
>>= cache
->sectors_per_block_shift
;
899 return to_oblock(block_nr
);
902 static bool accountable_bio(struct cache
*cache
, struct bio
*bio
)
904 return ((bio
->bi_bdev
== cache
->origin_dev
->bdev
) &&
905 bio_op(bio
) != REQ_OP_DISCARD
);
908 static void accounted_begin(struct cache
*cache
, struct bio
*bio
)
910 size_t pb_data_size
= get_per_bio_data_size(cache
);
911 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
913 if (accountable_bio(cache
, bio
)) {
914 pb
->len
= bio_sectors(bio
);
915 iot_io_begin(&cache
->origin_tracker
, pb
->len
);
919 static void accounted_complete(struct cache
*cache
, struct bio
*bio
)
921 size_t pb_data_size
= get_per_bio_data_size(cache
);
922 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
924 iot_io_end(&cache
->origin_tracker
, pb
->len
);
927 static void accounted_request(struct cache
*cache
, struct bio
*bio
)
929 accounted_begin(cache
, bio
);
930 generic_make_request(bio
);
933 static void issue_op(struct bio
*bio
, void *context
)
935 struct cache
*cache
= context
;
936 accounted_request(cache
, bio
);
939 static void defer_writethrough_bio(struct cache
*cache
, struct bio
*bio
)
943 spin_lock_irqsave(&cache
->lock
, flags
);
944 bio_list_add(&cache
->deferred_writethrough_bios
, bio
);
945 spin_unlock_irqrestore(&cache
->lock
, flags
);
947 wake_deferred_writethrough_worker(cache
);
950 static void writethrough_endio(struct bio
*bio
)
952 struct per_bio_data
*pb
= get_per_bio_data(bio
, PB_DATA_SIZE_WT
);
954 dm_unhook_bio(&pb
->hook_info
, bio
);
961 dm_bio_restore(&pb
->bio_details
, bio
);
962 remap_to_cache(pb
->cache
, bio
, pb
->cblock
);
965 * We can't issue this bio directly, since we're in interrupt
966 * context. So it gets put on a bio list for processing by the
969 defer_writethrough_bio(pb
->cache
, bio
);
973 * FIXME: send in parallel, huge latency as is.
974 * When running in writethrough mode we need to send writes to clean blocks
975 * to both the cache and origin devices. In future we'd like to clone the
976 * bio and send them in parallel, but for now we're doing them in
977 * series as this is easier.
979 static void remap_to_origin_then_cache(struct cache
*cache
, struct bio
*bio
,
980 dm_oblock_t oblock
, dm_cblock_t cblock
)
982 struct per_bio_data
*pb
= get_per_bio_data(bio
, PB_DATA_SIZE_WT
);
986 dm_hook_bio(&pb
->hook_info
, bio
, writethrough_endio
, NULL
);
987 dm_bio_record(&pb
->bio_details
, bio
);
989 remap_to_origin_clear_discard(pb
->cache
, bio
, oblock
);
992 /*----------------------------------------------------------------
994 *--------------------------------------------------------------*/
995 static enum cache_metadata_mode
get_cache_mode(struct cache
*cache
)
997 return cache
->features
.mode
;
1000 static const char *cache_device_name(struct cache
*cache
)
1002 return dm_device_name(dm_table_get_md(cache
->ti
->table
));
1005 static void notify_mode_switch(struct cache
*cache
, enum cache_metadata_mode mode
)
1007 const char *descs
[] = {
1013 dm_table_event(cache
->ti
->table
);
1014 DMINFO("%s: switching cache to %s mode",
1015 cache_device_name(cache
), descs
[(int)mode
]);
1018 static void set_cache_mode(struct cache
*cache
, enum cache_metadata_mode new_mode
)
1021 enum cache_metadata_mode old_mode
= get_cache_mode(cache
);
1023 if (dm_cache_metadata_needs_check(cache
->cmd
, &needs_check
)) {
1024 DMERR("%s: unable to read needs_check flag, setting failure mode.",
1025 cache_device_name(cache
));
1029 if (new_mode
== CM_WRITE
&& needs_check
) {
1030 DMERR("%s: unable to switch cache to write mode until repaired.",
1031 cache_device_name(cache
));
1032 if (old_mode
!= new_mode
)
1033 new_mode
= old_mode
;
1035 new_mode
= CM_READ_ONLY
;
1038 /* Never move out of fail mode */
1039 if (old_mode
== CM_FAIL
)
1045 dm_cache_metadata_set_read_only(cache
->cmd
);
1049 dm_cache_metadata_set_read_write(cache
->cmd
);
1053 cache
->features
.mode
= new_mode
;
1055 if (new_mode
!= old_mode
)
1056 notify_mode_switch(cache
, new_mode
);
1059 static void abort_transaction(struct cache
*cache
)
1061 const char *dev_name
= cache_device_name(cache
);
1063 if (get_cache_mode(cache
) >= CM_READ_ONLY
)
1066 if (dm_cache_metadata_set_needs_check(cache
->cmd
)) {
1067 DMERR("%s: failed to set 'needs_check' flag in metadata", dev_name
);
1068 set_cache_mode(cache
, CM_FAIL
);
1071 DMERR_LIMIT("%s: aborting current metadata transaction", dev_name
);
1072 if (dm_cache_metadata_abort(cache
->cmd
)) {
1073 DMERR("%s: failed to abort metadata transaction", dev_name
);
1074 set_cache_mode(cache
, CM_FAIL
);
1078 static void metadata_operation_failed(struct cache
*cache
, const char *op
, int r
)
1080 DMERR_LIMIT("%s: metadata operation '%s' failed: error = %d",
1081 cache_device_name(cache
), op
, r
);
1082 abort_transaction(cache
);
1083 set_cache_mode(cache
, CM_READ_ONLY
);
1086 /*----------------------------------------------------------------*/
1088 static void load_stats(struct cache
*cache
)
1090 struct dm_cache_statistics stats
;
1092 dm_cache_metadata_get_stats(cache
->cmd
, &stats
);
1093 atomic_set(&cache
->stats
.read_hit
, stats
.read_hits
);
1094 atomic_set(&cache
->stats
.read_miss
, stats
.read_misses
);
1095 atomic_set(&cache
->stats
.write_hit
, stats
.write_hits
);
1096 atomic_set(&cache
->stats
.write_miss
, stats
.write_misses
);
1099 static void save_stats(struct cache
*cache
)
1101 struct dm_cache_statistics stats
;
1103 if (get_cache_mode(cache
) >= CM_READ_ONLY
)
1106 stats
.read_hits
= atomic_read(&cache
->stats
.read_hit
);
1107 stats
.read_misses
= atomic_read(&cache
->stats
.read_miss
);
1108 stats
.write_hits
= atomic_read(&cache
->stats
.write_hit
);
1109 stats
.write_misses
= atomic_read(&cache
->stats
.write_miss
);
1111 dm_cache_metadata_set_stats(cache
->cmd
, &stats
);
1114 static void update_stats(struct cache_stats
*stats
, enum policy_operation op
)
1117 case POLICY_PROMOTE
:
1118 atomic_inc(&stats
->promotion
);
1122 atomic_inc(&stats
->demotion
);
1125 case POLICY_WRITEBACK
:
1126 atomic_inc(&stats
->writeback
);
1131 /*----------------------------------------------------------------
1132 * Migration processing
1134 * Migration covers moving data from the origin device to the cache, or
1136 *--------------------------------------------------------------*/
1138 static void inc_io_migrations(struct cache
*cache
)
1140 atomic_inc(&cache
->nr_io_migrations
);
1143 static void dec_io_migrations(struct cache
*cache
)
1145 atomic_dec(&cache
->nr_io_migrations
);
1148 static bool discard_or_flush(struct bio
*bio
)
1150 return bio_op(bio
) == REQ_OP_DISCARD
|| op_is_flush(bio
->bi_opf
);
1153 static void calc_discard_block_range(struct cache
*cache
, struct bio
*bio
,
1154 dm_dblock_t
*b
, dm_dblock_t
*e
)
1156 sector_t sb
= bio
->bi_iter
.bi_sector
;
1157 sector_t se
= bio_end_sector(bio
);
1159 *b
= to_dblock(dm_sector_div_up(sb
, cache
->discard_block_size
));
1161 if (se
- sb
< cache
->discard_block_size
)
1164 *e
= to_dblock(block_div(se
, cache
->discard_block_size
));
1167 /*----------------------------------------------------------------*/
1169 static void prevent_background_work(struct cache
*cache
)
1172 down_write(&cache
->background_work_lock
);
1176 static void allow_background_work(struct cache
*cache
)
1179 up_write(&cache
->background_work_lock
);
1183 static bool background_work_begin(struct cache
*cache
)
1188 r
= down_read_trylock(&cache
->background_work_lock
);
1194 static void background_work_end(struct cache
*cache
)
1197 up_read(&cache
->background_work_lock
);
1201 /*----------------------------------------------------------------*/
1203 static void quiesce(struct dm_cache_migration
*mg
,
1204 void (*continuation
)(struct work_struct
*))
1206 init_continuation(&mg
->k
, continuation
);
1207 dm_cell_quiesce_v2(mg
->cache
->prison
, mg
->cell
, &mg
->k
.ws
);
1210 static struct dm_cache_migration
*ws_to_mg(struct work_struct
*ws
)
1212 struct continuation
*k
= container_of(ws
, struct continuation
, ws
);
1213 return container_of(k
, struct dm_cache_migration
, k
);
1216 static void copy_complete(int read_err
, unsigned long write_err
, void *context
)
1218 struct dm_cache_migration
*mg
= container_of(context
, struct dm_cache_migration
, k
);
1220 if (read_err
|| write_err
)
1223 queue_continuation(mg
->cache
->wq
, &mg
->k
);
1226 static int copy(struct dm_cache_migration
*mg
, bool promote
)
1229 struct dm_io_region o_region
, c_region
;
1230 struct cache
*cache
= mg
->cache
;
1232 o_region
.bdev
= cache
->origin_dev
->bdev
;
1233 o_region
.sector
= from_oblock(mg
->op
->oblock
) * cache
->sectors_per_block
;
1234 o_region
.count
= cache
->sectors_per_block
;
1236 c_region
.bdev
= cache
->cache_dev
->bdev
;
1237 c_region
.sector
= from_cblock(mg
->op
->cblock
) * cache
->sectors_per_block
;
1238 c_region
.count
= cache
->sectors_per_block
;
1241 r
= dm_kcopyd_copy(cache
->copier
, &o_region
, 1, &c_region
, 0, copy_complete
, &mg
->k
);
1243 r
= dm_kcopyd_copy(cache
->copier
, &c_region
, 1, &o_region
, 0, copy_complete
, &mg
->k
);
1248 static void bio_drop_shared_lock(struct cache
*cache
, struct bio
*bio
)
1250 size_t pb_data_size
= get_per_bio_data_size(cache
);
1251 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
1253 if (pb
->cell
&& dm_cell_put_v2(cache
->prison
, pb
->cell
))
1254 free_prison_cell(cache
, pb
->cell
);
1258 static void overwrite_endio(struct bio
*bio
)
1260 struct dm_cache_migration
*mg
= bio
->bi_private
;
1261 struct cache
*cache
= mg
->cache
;
1262 size_t pb_data_size
= get_per_bio_data_size(cache
);
1263 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
1265 dm_unhook_bio(&pb
->hook_info
, bio
);
1268 mg
->k
.input
= bio
->bi_error
;
1270 queue_continuation(mg
->cache
->wq
, &mg
->k
);
1273 static void overwrite(struct dm_cache_migration
*mg
,
1274 void (*continuation
)(struct work_struct
*))
1276 struct bio
*bio
= mg
->overwrite_bio
;
1277 size_t pb_data_size
= get_per_bio_data_size(mg
->cache
);
1278 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
1280 dm_hook_bio(&pb
->hook_info
, bio
, overwrite_endio
, mg
);
1283 * The overwrite bio is part of the copy operation, as such it does
1284 * not set/clear discard or dirty flags.
1286 if (mg
->op
->op
== POLICY_PROMOTE
)
1287 remap_to_cache(mg
->cache
, bio
, mg
->op
->cblock
);
1289 remap_to_origin(mg
->cache
, bio
);
1291 init_continuation(&mg
->k
, continuation
);
1292 accounted_request(mg
->cache
, bio
);
1298 * 1) exclusive lock preventing WRITEs
1300 * 3) copy or issue overwrite bio
1301 * 4) upgrade to exclusive lock preventing READs and WRITEs
1303 * 6) update metadata and commit
1306 static void mg_complete(struct dm_cache_migration
*mg
, bool success
)
1308 struct bio_list bios
;
1309 struct cache
*cache
= mg
->cache
;
1310 struct policy_work
*op
= mg
->op
;
1311 dm_cblock_t cblock
= op
->cblock
;
1314 update_stats(&cache
->stats
, op
->op
);
1317 case POLICY_PROMOTE
:
1318 clear_discard(cache
, oblock_to_dblock(cache
, op
->oblock
));
1319 policy_complete_background_work(cache
->policy
, op
, success
);
1321 if (mg
->overwrite_bio
) {
1323 force_set_dirty(cache
, cblock
);
1325 mg
->overwrite_bio
->bi_error
= (mg
->k
.input
? : -EIO
);
1326 bio_endio(mg
->overwrite_bio
);
1329 force_clear_dirty(cache
, cblock
);
1330 dec_io_migrations(cache
);
1336 * We clear dirty here to update the nr_dirty counter.
1339 force_clear_dirty(cache
, cblock
);
1340 policy_complete_background_work(cache
->policy
, op
, success
);
1341 dec_io_migrations(cache
);
1344 case POLICY_WRITEBACK
:
1346 force_clear_dirty(cache
, cblock
);
1347 policy_complete_background_work(cache
->policy
, op
, success
);
1348 dec_io_migrations(cache
);
1352 bio_list_init(&bios
);
1354 if (dm_cell_unlock_v2(cache
->prison
, mg
->cell
, &bios
))
1355 free_prison_cell(cache
, mg
->cell
);
1359 defer_bios(cache
, &bios
);
1360 wake_migration_worker(cache
);
1362 background_work_end(cache
);
1365 static void mg_success(struct work_struct
*ws
)
1367 struct dm_cache_migration
*mg
= ws_to_mg(ws
);
1368 mg_complete(mg
, mg
->k
.input
== 0);
1371 static void mg_update_metadata(struct work_struct
*ws
)
1374 struct dm_cache_migration
*mg
= ws_to_mg(ws
);
1375 struct cache
*cache
= mg
->cache
;
1376 struct policy_work
*op
= mg
->op
;
1379 case POLICY_PROMOTE
:
1380 r
= dm_cache_insert_mapping(cache
->cmd
, op
->cblock
, op
->oblock
);
1382 DMERR_LIMIT("%s: migration failed; couldn't insert mapping",
1383 cache_device_name(cache
));
1384 metadata_operation_failed(cache
, "dm_cache_insert_mapping", r
);
1386 mg_complete(mg
, false);
1389 mg_complete(mg
, true);
1393 r
= dm_cache_remove_mapping(cache
->cmd
, op
->cblock
);
1395 DMERR_LIMIT("%s: migration failed; couldn't update on disk metadata",
1396 cache_device_name(cache
));
1397 metadata_operation_failed(cache
, "dm_cache_remove_mapping", r
);
1399 mg_complete(mg
, false);
1404 * It would be nice if we only had to commit when a REQ_FLUSH
1405 * comes through. But there's one scenario that we have to
1408 * - vblock x in a cache block
1410 * - cache block gets reallocated and over written
1413 * When we recover, because there was no commit the cache will
1414 * rollback to having the data for vblock x in the cache block.
1415 * But the cache block has since been overwritten, so it'll end
1416 * up pointing to data that was never in 'x' during the history
1419 * To avoid this issue we require a commit as part of the
1420 * demotion operation.
1422 init_continuation(&mg
->k
, mg_success
);
1423 continue_after_commit(&cache
->committer
, &mg
->k
);
1424 schedule_commit(&cache
->committer
);
1427 case POLICY_WRITEBACK
:
1428 mg_complete(mg
, true);
1433 static void mg_update_metadata_after_copy(struct work_struct
*ws
)
1435 struct dm_cache_migration
*mg
= ws_to_mg(ws
);
1438 * Did the copy succeed?
1441 mg_complete(mg
, false);
1443 mg_update_metadata(ws
);
1446 static void mg_upgrade_lock(struct work_struct
*ws
)
1449 struct dm_cache_migration
*mg
= ws_to_mg(ws
);
1452 * Did the copy succeed?
1455 mg_complete(mg
, false);
1459 * Now we want the lock to prevent both reads and writes.
1461 r
= dm_cell_lock_promote_v2(mg
->cache
->prison
, mg
->cell
,
1462 READ_WRITE_LOCK_LEVEL
);
1464 mg_complete(mg
, false);
1467 quiesce(mg
, mg_update_metadata
);
1470 mg_update_metadata(ws
);
1474 static void mg_copy(struct work_struct
*ws
)
1477 struct dm_cache_migration
*mg
= ws_to_mg(ws
);
1479 if (mg
->overwrite_bio
) {
1481 * It's safe to do this here, even though it's new data
1482 * because all IO has been locked out of the block.
1484 * mg_lock_writes() already took READ_WRITE_LOCK_LEVEL
1485 * so _not_ using mg_upgrade_lock() as continutation.
1487 overwrite(mg
, mg_update_metadata_after_copy
);
1490 struct cache
*cache
= mg
->cache
;
1491 struct policy_work
*op
= mg
->op
;
1492 bool is_policy_promote
= (op
->op
== POLICY_PROMOTE
);
1494 if ((!is_policy_promote
&& !is_dirty(cache
, op
->cblock
)) ||
1495 is_discarded_oblock(cache
, op
->oblock
)) {
1496 mg_upgrade_lock(ws
);
1500 init_continuation(&mg
->k
, mg_upgrade_lock
);
1502 r
= copy(mg
, is_policy_promote
);
1504 DMERR_LIMIT("%s: migration copy failed", cache_device_name(cache
));
1506 mg_complete(mg
, false);
1511 static int mg_lock_writes(struct dm_cache_migration
*mg
)
1514 struct dm_cell_key_v2 key
;
1515 struct cache
*cache
= mg
->cache
;
1516 struct dm_bio_prison_cell_v2
*prealloc
;
1518 prealloc
= alloc_prison_cell(cache
);
1520 DMERR_LIMIT("%s: alloc_prison_cell failed", cache_device_name(cache
));
1521 mg_complete(mg
, false);
1526 * Prevent writes to the block, but allow reads to continue.
1527 * Unless we're using an overwrite bio, in which case we lock
1530 build_key(mg
->op
->oblock
, oblock_succ(mg
->op
->oblock
), &key
);
1531 r
= dm_cell_lock_v2(cache
->prison
, &key
,
1532 mg
->overwrite_bio
? READ_WRITE_LOCK_LEVEL
: WRITE_LOCK_LEVEL
,
1533 prealloc
, &mg
->cell
);
1535 free_prison_cell(cache
, prealloc
);
1536 mg_complete(mg
, false);
1540 if (mg
->cell
!= prealloc
)
1541 free_prison_cell(cache
, prealloc
);
1546 quiesce(mg
, mg_copy
);
1551 static int mg_start(struct cache
*cache
, struct policy_work
*op
, struct bio
*bio
)
1553 struct dm_cache_migration
*mg
;
1555 if (!background_work_begin(cache
)) {
1556 policy_complete_background_work(cache
->policy
, op
, false);
1560 mg
= alloc_migration(cache
);
1562 policy_complete_background_work(cache
->policy
, op
, false);
1563 background_work_end(cache
);
1567 memset(mg
, 0, sizeof(*mg
));
1571 mg
->overwrite_bio
= bio
;
1574 inc_io_migrations(cache
);
1576 return mg_lock_writes(mg
);
1579 /*----------------------------------------------------------------
1580 * invalidation processing
1581 *--------------------------------------------------------------*/
1583 static void invalidate_complete(struct dm_cache_migration
*mg
, bool success
)
1585 struct bio_list bios
;
1586 struct cache
*cache
= mg
->cache
;
1588 bio_list_init(&bios
);
1589 if (dm_cell_unlock_v2(cache
->prison
, mg
->cell
, &bios
))
1590 free_prison_cell(cache
, mg
->cell
);
1592 if (!success
&& mg
->overwrite_bio
)
1593 bio_io_error(mg
->overwrite_bio
);
1596 defer_bios(cache
, &bios
);
1598 background_work_end(cache
);
1601 static void invalidate_completed(struct work_struct
*ws
)
1603 struct dm_cache_migration
*mg
= ws_to_mg(ws
);
1604 invalidate_complete(mg
, !mg
->k
.input
);
1607 static int invalidate_cblock(struct cache
*cache
, dm_cblock_t cblock
)
1609 int r
= policy_invalidate_mapping(cache
->policy
, cblock
);
1611 r
= dm_cache_remove_mapping(cache
->cmd
, cblock
);
1613 DMERR_LIMIT("%s: invalidation failed; couldn't update on disk metadata",
1614 cache_device_name(cache
));
1615 metadata_operation_failed(cache
, "dm_cache_remove_mapping", r
);
1618 } else if (r
== -ENODATA
) {
1620 * Harmless, already unmapped.
1625 DMERR("%s: policy_invalidate_mapping failed", cache_device_name(cache
));
1630 static void invalidate_remove(struct work_struct
*ws
)
1633 struct dm_cache_migration
*mg
= ws_to_mg(ws
);
1634 struct cache
*cache
= mg
->cache
;
1636 r
= invalidate_cblock(cache
, mg
->invalidate_cblock
);
1638 invalidate_complete(mg
, false);
1642 init_continuation(&mg
->k
, invalidate_completed
);
1643 continue_after_commit(&cache
->committer
, &mg
->k
);
1644 remap_to_origin_clear_discard(cache
, mg
->overwrite_bio
, mg
->invalidate_oblock
);
1645 mg
->overwrite_bio
= NULL
;
1646 schedule_commit(&cache
->committer
);
1649 static int invalidate_lock(struct dm_cache_migration
*mg
)
1652 struct dm_cell_key_v2 key
;
1653 struct cache
*cache
= mg
->cache
;
1654 struct dm_bio_prison_cell_v2
*prealloc
;
1656 prealloc
= alloc_prison_cell(cache
);
1658 invalidate_complete(mg
, false);
1662 build_key(mg
->invalidate_oblock
, oblock_succ(mg
->invalidate_oblock
), &key
);
1663 r
= dm_cell_lock_v2(cache
->prison
, &key
,
1664 READ_WRITE_LOCK_LEVEL
, prealloc
, &mg
->cell
);
1666 free_prison_cell(cache
, prealloc
);
1667 invalidate_complete(mg
, false);
1671 if (mg
->cell
!= prealloc
)
1672 free_prison_cell(cache
, prealloc
);
1675 quiesce(mg
, invalidate_remove
);
1679 * We can't call invalidate_remove() directly here because we
1680 * might still be in request context.
1682 init_continuation(&mg
->k
, invalidate_remove
);
1683 queue_work(cache
->wq
, &mg
->k
.ws
);
1689 static int invalidate_start(struct cache
*cache
, dm_cblock_t cblock
,
1690 dm_oblock_t oblock
, struct bio
*bio
)
1692 struct dm_cache_migration
*mg
;
1694 if (!background_work_begin(cache
))
1697 mg
= alloc_migration(cache
);
1699 background_work_end(cache
);
1703 memset(mg
, 0, sizeof(*mg
));
1706 mg
->overwrite_bio
= bio
;
1707 mg
->invalidate_cblock
= cblock
;
1708 mg
->invalidate_oblock
= oblock
;
1710 return invalidate_lock(mg
);
1713 /*----------------------------------------------------------------
1715 *--------------------------------------------------------------*/
1723 static enum busy
spare_migration_bandwidth(struct cache
*cache
)
1725 bool idle
= iot_idle_for(&cache
->origin_tracker
, HZ
);
1726 sector_t current_volume
= (atomic_read(&cache
->nr_io_migrations
) + 1) *
1727 cache
->sectors_per_block
;
1729 if (current_volume
<= cache
->migration_threshold
)
1730 return idle
? IDLE
: MODERATE
;
1732 return idle
? MODERATE
: BUSY
;
1735 static void inc_hit_counter(struct cache
*cache
, struct bio
*bio
)
1737 atomic_inc(bio_data_dir(bio
) == READ
?
1738 &cache
->stats
.read_hit
: &cache
->stats
.write_hit
);
1741 static void inc_miss_counter(struct cache
*cache
, struct bio
*bio
)
1743 atomic_inc(bio_data_dir(bio
) == READ
?
1744 &cache
->stats
.read_miss
: &cache
->stats
.write_miss
);
1747 /*----------------------------------------------------------------*/
1749 static bool bio_writes_complete_block(struct cache
*cache
, struct bio
*bio
)
1751 return (bio_data_dir(bio
) == WRITE
) &&
1752 (bio
->bi_iter
.bi_size
== (cache
->sectors_per_block
<< SECTOR_SHIFT
));
1755 static bool optimisable_bio(struct cache
*cache
, struct bio
*bio
, dm_oblock_t block
)
1757 return writeback_mode(&cache
->features
) &&
1758 (is_discarded_oblock(cache
, block
) || bio_writes_complete_block(cache
, bio
));
1761 static int map_bio(struct cache
*cache
, struct bio
*bio
, dm_oblock_t block
,
1762 bool *commit_needed
)
1765 bool rb
, background_queued
;
1767 size_t pb_data_size
= get_per_bio_data_size(cache
);
1768 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
1770 *commit_needed
= false;
1772 rb
= bio_detain_shared(cache
, block
, bio
);
1775 * An exclusive lock is held for this block, so we have to
1776 * wait. We set the commit_needed flag so the current
1777 * transaction will be committed asap, allowing this lock
1780 *commit_needed
= true;
1781 return DM_MAPIO_SUBMITTED
;
1784 data_dir
= bio_data_dir(bio
);
1786 if (optimisable_bio(cache
, bio
, block
)) {
1787 struct policy_work
*op
= NULL
;
1789 r
= policy_lookup_with_work(cache
->policy
, block
, &cblock
, data_dir
, true, &op
);
1790 if (unlikely(r
&& r
!= -ENOENT
)) {
1791 DMERR_LIMIT("%s: policy_lookup_with_work() failed with r = %d",
1792 cache_device_name(cache
), r
);
1794 return DM_MAPIO_SUBMITTED
;
1797 if (r
== -ENOENT
&& op
) {
1798 bio_drop_shared_lock(cache
, bio
);
1799 BUG_ON(op
->op
!= POLICY_PROMOTE
);
1800 mg_start(cache
, op
, bio
);
1801 return DM_MAPIO_SUBMITTED
;
1804 r
= policy_lookup(cache
->policy
, block
, &cblock
, data_dir
, false, &background_queued
);
1805 if (unlikely(r
&& r
!= -ENOENT
)) {
1806 DMERR_LIMIT("%s: policy_lookup() failed with r = %d",
1807 cache_device_name(cache
), r
);
1809 return DM_MAPIO_SUBMITTED
;
1812 if (background_queued
)
1813 wake_migration_worker(cache
);
1820 inc_miss_counter(cache
, bio
);
1821 if (pb
->req_nr
== 0) {
1822 accounted_begin(cache
, bio
);
1823 remap_to_origin_clear_discard(cache
, bio
, block
);
1827 * This is a duplicate writethrough io that is no
1828 * longer needed because the block has been demoted.
1831 return DM_MAPIO_SUBMITTED
;
1837 inc_hit_counter(cache
, bio
);
1840 * Passthrough always maps to the origin, invalidating any
1841 * cache blocks that are written to.
1843 if (passthrough_mode(&cache
->features
)) {
1844 if (bio_data_dir(bio
) == WRITE
) {
1845 bio_drop_shared_lock(cache
, bio
);
1846 atomic_inc(&cache
->stats
.demotion
);
1847 invalidate_start(cache
, cblock
, block
, bio
);
1849 remap_to_origin_clear_discard(cache
, bio
, block
);
1852 if (bio_data_dir(bio
) == WRITE
&& writethrough_mode(&cache
->features
) &&
1853 !is_dirty(cache
, cblock
)) {
1854 remap_to_origin_then_cache(cache
, bio
, block
, cblock
);
1855 accounted_begin(cache
, bio
);
1857 remap_to_cache_dirty(cache
, bio
, block
, cblock
);
1862 * dm core turns FUA requests into a separate payload and FLUSH req.
1864 if (bio
->bi_opf
& REQ_FUA
) {
1866 * issue_after_commit will call accounted_begin a second time. So
1867 * we call accounted_complete() to avoid double accounting.
1869 accounted_complete(cache
, bio
);
1870 issue_after_commit(&cache
->committer
, bio
);
1871 *commit_needed
= true;
1872 return DM_MAPIO_SUBMITTED
;
1875 return DM_MAPIO_REMAPPED
;
1878 static bool process_bio(struct cache
*cache
, struct bio
*bio
)
1882 if (map_bio(cache
, bio
, get_bio_block(cache
, bio
), &commit_needed
) == DM_MAPIO_REMAPPED
)
1883 generic_make_request(bio
);
1885 return commit_needed
;
1889 * A non-zero return indicates read_only or fail_io mode.
1891 static int commit(struct cache
*cache
, bool clean_shutdown
)
1895 if (get_cache_mode(cache
) >= CM_READ_ONLY
)
1898 atomic_inc(&cache
->stats
.commit_count
);
1899 r
= dm_cache_commit(cache
->cmd
, clean_shutdown
);
1901 metadata_operation_failed(cache
, "dm_cache_commit", r
);
1907 * Used by the batcher.
1909 static int commit_op(void *context
)
1911 struct cache
*cache
= context
;
1913 if (dm_cache_changed_this_transaction(cache
->cmd
))
1914 return commit(cache
, false);
1919 /*----------------------------------------------------------------*/
1921 static bool process_flush_bio(struct cache
*cache
, struct bio
*bio
)
1923 size_t pb_data_size
= get_per_bio_data_size(cache
);
1924 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
1927 remap_to_origin(cache
, bio
);
1929 remap_to_cache(cache
, bio
, 0);
1931 issue_after_commit(&cache
->committer
, bio
);
1935 static bool process_discard_bio(struct cache
*cache
, struct bio
*bio
)
1939 // FIXME: do we need to lock the region? Or can we just assume the
1940 // user wont be so foolish as to issue discard concurrently with
1942 calc_discard_block_range(cache
, bio
, &b
, &e
);
1944 set_discard(cache
, b
);
1945 b
= to_dblock(from_dblock(b
) + 1);
1953 static void process_deferred_bios(struct work_struct
*ws
)
1955 struct cache
*cache
= container_of(ws
, struct cache
, deferred_bio_worker
);
1957 unsigned long flags
;
1958 bool commit_needed
= false;
1959 struct bio_list bios
;
1962 bio_list_init(&bios
);
1964 spin_lock_irqsave(&cache
->lock
, flags
);
1965 bio_list_merge(&bios
, &cache
->deferred_bios
);
1966 bio_list_init(&cache
->deferred_bios
);
1967 spin_unlock_irqrestore(&cache
->lock
, flags
);
1969 while ((bio
= bio_list_pop(&bios
))) {
1970 if (bio
->bi_opf
& REQ_PREFLUSH
)
1971 commit_needed
= process_flush_bio(cache
, bio
) || commit_needed
;
1973 else if (bio_op(bio
) == REQ_OP_DISCARD
)
1974 commit_needed
= process_discard_bio(cache
, bio
) || commit_needed
;
1977 commit_needed
= process_bio(cache
, bio
) || commit_needed
;
1981 schedule_commit(&cache
->committer
);
1984 static void process_deferred_writethrough_bios(struct work_struct
*ws
)
1986 struct cache
*cache
= container_of(ws
, struct cache
, deferred_writethrough_worker
);
1988 unsigned long flags
;
1989 struct bio_list bios
;
1992 bio_list_init(&bios
);
1994 spin_lock_irqsave(&cache
->lock
, flags
);
1995 bio_list_merge(&bios
, &cache
->deferred_writethrough_bios
);
1996 bio_list_init(&cache
->deferred_writethrough_bios
);
1997 spin_unlock_irqrestore(&cache
->lock
, flags
);
2000 * These bios have already been through accounted_begin()
2002 while ((bio
= bio_list_pop(&bios
)))
2003 generic_make_request(bio
);
2006 /*----------------------------------------------------------------
2008 *--------------------------------------------------------------*/
2010 static void requeue_deferred_bios(struct cache
*cache
)
2013 struct bio_list bios
;
2015 bio_list_init(&bios
);
2016 bio_list_merge(&bios
, &cache
->deferred_bios
);
2017 bio_list_init(&cache
->deferred_bios
);
2019 while ((bio
= bio_list_pop(&bios
))) {
2020 bio
->bi_error
= DM_ENDIO_REQUEUE
;
2026 * We want to commit periodically so that not too much
2027 * unwritten metadata builds up.
2029 static void do_waker(struct work_struct
*ws
)
2031 struct cache
*cache
= container_of(to_delayed_work(ws
), struct cache
, waker
);
2033 policy_tick(cache
->policy
, true);
2034 wake_migration_worker(cache
);
2035 schedule_commit(&cache
->committer
);
2036 queue_delayed_work(cache
->wq
, &cache
->waker
, COMMIT_PERIOD
);
2039 static void check_migrations(struct work_struct
*ws
)
2042 struct policy_work
*op
;
2043 struct cache
*cache
= container_of(ws
, struct cache
, migration_worker
);
2047 b
= spare_migration_bandwidth(cache
);
2051 r
= policy_get_background_work(cache
->policy
, b
== IDLE
, &op
);
2056 DMERR_LIMIT("%s: policy_background_work failed",
2057 cache_device_name(cache
));
2061 r
= mg_start(cache
, op
, NULL
);
2067 /*----------------------------------------------------------------
2069 *--------------------------------------------------------------*/
2072 * This function gets called on the error paths of the constructor, so we
2073 * have to cope with a partially initialised struct.
2075 static void destroy(struct cache
*cache
)
2079 mempool_destroy(cache
->migration_pool
);
2082 dm_bio_prison_destroy_v2(cache
->prison
);
2085 destroy_workqueue(cache
->wq
);
2087 if (cache
->dirty_bitset
)
2088 free_bitset(cache
->dirty_bitset
);
2090 if (cache
->discard_bitset
)
2091 free_bitset(cache
->discard_bitset
);
2094 dm_kcopyd_client_destroy(cache
->copier
);
2097 dm_cache_metadata_close(cache
->cmd
);
2099 if (cache
->metadata_dev
)
2100 dm_put_device(cache
->ti
, cache
->metadata_dev
);
2102 if (cache
->origin_dev
)
2103 dm_put_device(cache
->ti
, cache
->origin_dev
);
2105 if (cache
->cache_dev
)
2106 dm_put_device(cache
->ti
, cache
->cache_dev
);
2109 dm_cache_policy_destroy(cache
->policy
);
2111 for (i
= 0; i
< cache
->nr_ctr_args
; i
++)
2112 kfree(cache
->ctr_args
[i
]);
2113 kfree(cache
->ctr_args
);
2118 static void cache_dtr(struct dm_target
*ti
)
2120 struct cache
*cache
= ti
->private;
2125 static sector_t
get_dev_size(struct dm_dev
*dev
)
2127 return i_size_read(dev
->bdev
->bd_inode
) >> SECTOR_SHIFT
;
2130 /*----------------------------------------------------------------*/
2133 * Construct a cache device mapping.
2135 * cache <metadata dev> <cache dev> <origin dev> <block size>
2136 * <#feature args> [<feature arg>]*
2137 * <policy> <#policy args> [<policy arg>]*
2139 * metadata dev : fast device holding the persistent metadata
2140 * cache dev : fast device holding cached data blocks
2141 * origin dev : slow device holding original data blocks
2142 * block size : cache unit size in sectors
2144 * #feature args : number of feature arguments passed
2145 * feature args : writethrough. (The default is writeback.)
2147 * policy : the replacement policy to use
2148 * #policy args : an even number of policy arguments corresponding
2149 * to key/value pairs passed to the policy
2150 * policy args : key/value pairs passed to the policy
2151 * E.g. 'sequential_threshold 1024'
2152 * See cache-policies.txt for details.
2154 * Optional feature arguments are:
2155 * writethrough : write through caching that prohibits cache block
2156 * content from being different from origin block content.
2157 * Without this argument, the default behaviour is to write
2158 * back cache block contents later for performance reasons,
2159 * so they may differ from the corresponding origin blocks.
2162 struct dm_target
*ti
;
2164 struct dm_dev
*metadata_dev
;
2166 struct dm_dev
*cache_dev
;
2167 sector_t cache_sectors
;
2169 struct dm_dev
*origin_dev
;
2170 sector_t origin_sectors
;
2172 uint32_t block_size
;
2174 const char *policy_name
;
2176 const char **policy_argv
;
2178 struct cache_features features
;
2181 static void destroy_cache_args(struct cache_args
*ca
)
2183 if (ca
->metadata_dev
)
2184 dm_put_device(ca
->ti
, ca
->metadata_dev
);
2187 dm_put_device(ca
->ti
, ca
->cache_dev
);
2190 dm_put_device(ca
->ti
, ca
->origin_dev
);
2195 static bool at_least_one_arg(struct dm_arg_set
*as
, char **error
)
2198 *error
= "Insufficient args";
2205 static int parse_metadata_dev(struct cache_args
*ca
, struct dm_arg_set
*as
,
2209 sector_t metadata_dev_size
;
2210 char b
[BDEVNAME_SIZE
];
2212 if (!at_least_one_arg(as
, error
))
2215 r
= dm_get_device(ca
->ti
, dm_shift_arg(as
), FMODE_READ
| FMODE_WRITE
,
2218 *error
= "Error opening metadata device";
2222 metadata_dev_size
= get_dev_size(ca
->metadata_dev
);
2223 if (metadata_dev_size
> DM_CACHE_METADATA_MAX_SECTORS_WARNING
)
2224 DMWARN("Metadata device %s is larger than %u sectors: excess space will not be used.",
2225 bdevname(ca
->metadata_dev
->bdev
, b
), THIN_METADATA_MAX_SECTORS
);
2230 static int parse_cache_dev(struct cache_args
*ca
, struct dm_arg_set
*as
,
2235 if (!at_least_one_arg(as
, error
))
2238 r
= dm_get_device(ca
->ti
, dm_shift_arg(as
), FMODE_READ
| FMODE_WRITE
,
2241 *error
= "Error opening cache device";
2244 ca
->cache_sectors
= get_dev_size(ca
->cache_dev
);
2249 static int parse_origin_dev(struct cache_args
*ca
, struct dm_arg_set
*as
,
2254 if (!at_least_one_arg(as
, error
))
2257 r
= dm_get_device(ca
->ti
, dm_shift_arg(as
), FMODE_READ
| FMODE_WRITE
,
2260 *error
= "Error opening origin device";
2264 ca
->origin_sectors
= get_dev_size(ca
->origin_dev
);
2265 if (ca
->ti
->len
> ca
->origin_sectors
) {
2266 *error
= "Device size larger than cached device";
2273 static int parse_block_size(struct cache_args
*ca
, struct dm_arg_set
*as
,
2276 unsigned long block_size
;
2278 if (!at_least_one_arg(as
, error
))
2281 if (kstrtoul(dm_shift_arg(as
), 10, &block_size
) || !block_size
||
2282 block_size
< DATA_DEV_BLOCK_SIZE_MIN_SECTORS
||
2283 block_size
> DATA_DEV_BLOCK_SIZE_MAX_SECTORS
||
2284 block_size
& (DATA_DEV_BLOCK_SIZE_MIN_SECTORS
- 1)) {
2285 *error
= "Invalid data block size";
2289 if (block_size
> ca
->cache_sectors
) {
2290 *error
= "Data block size is larger than the cache device";
2294 ca
->block_size
= block_size
;
2299 static void init_features(struct cache_features
*cf
)
2301 cf
->mode
= CM_WRITE
;
2302 cf
->io_mode
= CM_IO_WRITEBACK
;
2303 cf
->metadata_version
= 1;
2306 static int parse_features(struct cache_args
*ca
, struct dm_arg_set
*as
,
2309 static struct dm_arg _args
[] = {
2310 {0, 2, "Invalid number of cache feature arguments"},
2316 struct cache_features
*cf
= &ca
->features
;
2320 r
= dm_read_arg_group(_args
, as
, &argc
, error
);
2325 arg
= dm_shift_arg(as
);
2327 if (!strcasecmp(arg
, "writeback"))
2328 cf
->io_mode
= CM_IO_WRITEBACK
;
2330 else if (!strcasecmp(arg
, "writethrough"))
2331 cf
->io_mode
= CM_IO_WRITETHROUGH
;
2333 else if (!strcasecmp(arg
, "passthrough"))
2334 cf
->io_mode
= CM_IO_PASSTHROUGH
;
2336 else if (!strcasecmp(arg
, "metadata2"))
2337 cf
->metadata_version
= 2;
2340 *error
= "Unrecognised cache feature requested";
2348 static int parse_policy(struct cache_args
*ca
, struct dm_arg_set
*as
,
2351 static struct dm_arg _args
[] = {
2352 {0, 1024, "Invalid number of policy arguments"},
2357 if (!at_least_one_arg(as
, error
))
2360 ca
->policy_name
= dm_shift_arg(as
);
2362 r
= dm_read_arg_group(_args
, as
, &ca
->policy_argc
, error
);
2366 ca
->policy_argv
= (const char **)as
->argv
;
2367 dm_consume_args(as
, ca
->policy_argc
);
2372 static int parse_cache_args(struct cache_args
*ca
, int argc
, char **argv
,
2376 struct dm_arg_set as
;
2381 r
= parse_metadata_dev(ca
, &as
, error
);
2385 r
= parse_cache_dev(ca
, &as
, error
);
2389 r
= parse_origin_dev(ca
, &as
, error
);
2393 r
= parse_block_size(ca
, &as
, error
);
2397 r
= parse_features(ca
, &as
, error
);
2401 r
= parse_policy(ca
, &as
, error
);
2408 /*----------------------------------------------------------------*/
2410 static struct kmem_cache
*migration_cache
;
2412 #define NOT_CORE_OPTION 1
2414 static int process_config_option(struct cache
*cache
, const char *key
, const char *value
)
2418 if (!strcasecmp(key
, "migration_threshold")) {
2419 if (kstrtoul(value
, 10, &tmp
))
2422 cache
->migration_threshold
= tmp
;
2426 return NOT_CORE_OPTION
;
2429 static int set_config_value(struct cache
*cache
, const char *key
, const char *value
)
2431 int r
= process_config_option(cache
, key
, value
);
2433 if (r
== NOT_CORE_OPTION
)
2434 r
= policy_set_config_value(cache
->policy
, key
, value
);
2437 DMWARN("bad config value for %s: %s", key
, value
);
2442 static int set_config_values(struct cache
*cache
, int argc
, const char **argv
)
2447 DMWARN("Odd number of policy arguments given but they should be <key> <value> pairs.");
2452 r
= set_config_value(cache
, argv
[0], argv
[1]);
2463 static int create_cache_policy(struct cache
*cache
, struct cache_args
*ca
,
2466 struct dm_cache_policy
*p
= dm_cache_policy_create(ca
->policy_name
,
2468 cache
->origin_sectors
,
2469 cache
->sectors_per_block
);
2471 *error
= "Error creating cache's policy";
2475 BUG_ON(!cache
->policy
);
2481 * We want the discard block size to be at least the size of the cache
2482 * block size and have no more than 2^14 discard blocks across the origin.
2484 #define MAX_DISCARD_BLOCKS (1 << 14)
2486 static bool too_many_discard_blocks(sector_t discard_block_size
,
2487 sector_t origin_size
)
2489 (void) sector_div(origin_size
, discard_block_size
);
2491 return origin_size
> MAX_DISCARD_BLOCKS
;
2494 static sector_t
calculate_discard_block_size(sector_t cache_block_size
,
2495 sector_t origin_size
)
2497 sector_t discard_block_size
= cache_block_size
;
2500 while (too_many_discard_blocks(discard_block_size
, origin_size
))
2501 discard_block_size
*= 2;
2503 return discard_block_size
;
2506 static void set_cache_size(struct cache
*cache
, dm_cblock_t size
)
2508 dm_block_t nr_blocks
= from_cblock(size
);
2510 if (nr_blocks
> (1 << 20) && cache
->cache_size
!= size
)
2511 DMWARN_LIMIT("You have created a cache device with a lot of individual cache blocks (%llu)\n"
2512 "All these mappings can consume a lot of kernel memory, and take some time to read/write.\n"
2513 "Please consider increasing the cache block size to reduce the overall cache block count.",
2514 (unsigned long long) nr_blocks
);
2516 cache
->cache_size
= size
;
2519 static int is_congested(struct dm_dev
*dev
, int bdi_bits
)
2521 struct request_queue
*q
= bdev_get_queue(dev
->bdev
);
2522 return bdi_congested(q
->backing_dev_info
, bdi_bits
);
2525 static int cache_is_congested(struct dm_target_callbacks
*cb
, int bdi_bits
)
2527 struct cache
*cache
= container_of(cb
, struct cache
, callbacks
);
2529 return is_congested(cache
->origin_dev
, bdi_bits
) ||
2530 is_congested(cache
->cache_dev
, bdi_bits
);
2533 #define DEFAULT_MIGRATION_THRESHOLD 2048
2535 static int cache_create(struct cache_args
*ca
, struct cache
**result
)
2538 char **error
= &ca
->ti
->error
;
2539 struct cache
*cache
;
2540 struct dm_target
*ti
= ca
->ti
;
2541 dm_block_t origin_blocks
;
2542 struct dm_cache_metadata
*cmd
;
2543 bool may_format
= ca
->features
.mode
== CM_WRITE
;
2545 cache
= kzalloc(sizeof(*cache
), GFP_KERNEL
);
2550 ti
->private = cache
;
2551 ti
->num_flush_bios
= 2;
2552 ti
->flush_supported
= true;
2554 ti
->num_discard_bios
= 1;
2555 ti
->discards_supported
= true;
2556 ti
->split_discard_bios
= false;
2558 cache
->features
= ca
->features
;
2559 ti
->per_io_data_size
= get_per_bio_data_size(cache
);
2561 cache
->callbacks
.congested_fn
= cache_is_congested
;
2562 dm_table_add_target_callbacks(ti
->table
, &cache
->callbacks
);
2564 cache
->metadata_dev
= ca
->metadata_dev
;
2565 cache
->origin_dev
= ca
->origin_dev
;
2566 cache
->cache_dev
= ca
->cache_dev
;
2568 ca
->metadata_dev
= ca
->origin_dev
= ca
->cache_dev
= NULL
;
2570 origin_blocks
= cache
->origin_sectors
= ca
->origin_sectors
;
2571 origin_blocks
= block_div(origin_blocks
, ca
->block_size
);
2572 cache
->origin_blocks
= to_oblock(origin_blocks
);
2574 cache
->sectors_per_block
= ca
->block_size
;
2575 if (dm_set_target_max_io_len(ti
, cache
->sectors_per_block
)) {
2580 if (ca
->block_size
& (ca
->block_size
- 1)) {
2581 dm_block_t cache_size
= ca
->cache_sectors
;
2583 cache
->sectors_per_block_shift
= -1;
2584 cache_size
= block_div(cache_size
, ca
->block_size
);
2585 set_cache_size(cache
, to_cblock(cache_size
));
2587 cache
->sectors_per_block_shift
= __ffs(ca
->block_size
);
2588 set_cache_size(cache
, to_cblock(ca
->cache_sectors
>> cache
->sectors_per_block_shift
));
2591 r
= create_cache_policy(cache
, ca
, error
);
2595 cache
->policy_nr_args
= ca
->policy_argc
;
2596 cache
->migration_threshold
= DEFAULT_MIGRATION_THRESHOLD
;
2598 r
= set_config_values(cache
, ca
->policy_argc
, ca
->policy_argv
);
2600 *error
= "Error setting cache policy's config values";
2604 cmd
= dm_cache_metadata_open(cache
->metadata_dev
->bdev
,
2605 ca
->block_size
, may_format
,
2606 dm_cache_policy_get_hint_size(cache
->policy
),
2607 ca
->features
.metadata_version
);
2609 *error
= "Error creating metadata object";
2614 set_cache_mode(cache
, CM_WRITE
);
2615 if (get_cache_mode(cache
) != CM_WRITE
) {
2616 *error
= "Unable to get write access to metadata, please check/repair metadata.";
2621 if (passthrough_mode(&cache
->features
)) {
2624 r
= dm_cache_metadata_all_clean(cache
->cmd
, &all_clean
);
2626 *error
= "dm_cache_metadata_all_clean() failed";
2631 *error
= "Cannot enter passthrough mode unless all blocks are clean";
2636 policy_allow_migrations(cache
->policy
, false);
2639 spin_lock_init(&cache
->lock
);
2640 INIT_LIST_HEAD(&cache
->deferred_cells
);
2641 bio_list_init(&cache
->deferred_bios
);
2642 bio_list_init(&cache
->deferred_writethrough_bios
);
2643 atomic_set(&cache
->nr_allocated_migrations
, 0);
2644 atomic_set(&cache
->nr_io_migrations
, 0);
2645 init_waitqueue_head(&cache
->migration_wait
);
2648 atomic_set(&cache
->nr_dirty
, 0);
2649 cache
->dirty_bitset
= alloc_bitset(from_cblock(cache
->cache_size
));
2650 if (!cache
->dirty_bitset
) {
2651 *error
= "could not allocate dirty bitset";
2654 clear_bitset(cache
->dirty_bitset
, from_cblock(cache
->cache_size
));
2656 cache
->discard_block_size
=
2657 calculate_discard_block_size(cache
->sectors_per_block
,
2658 cache
->origin_sectors
);
2659 cache
->discard_nr_blocks
= to_dblock(dm_sector_div_up(cache
->origin_sectors
,
2660 cache
->discard_block_size
));
2661 cache
->discard_bitset
= alloc_bitset(from_dblock(cache
->discard_nr_blocks
));
2662 if (!cache
->discard_bitset
) {
2663 *error
= "could not allocate discard bitset";
2666 clear_bitset(cache
->discard_bitset
, from_dblock(cache
->discard_nr_blocks
));
2668 cache
->copier
= dm_kcopyd_client_create(&dm_kcopyd_throttle
);
2669 if (IS_ERR(cache
->copier
)) {
2670 *error
= "could not create kcopyd client";
2671 r
= PTR_ERR(cache
->copier
);
2675 cache
->wq
= alloc_workqueue("dm-" DM_MSG_PREFIX
, WQ_MEM_RECLAIM
, 0);
2677 *error
= "could not create workqueue for metadata object";
2680 INIT_WORK(&cache
->deferred_bio_worker
, process_deferred_bios
);
2681 INIT_WORK(&cache
->deferred_writethrough_worker
,
2682 process_deferred_writethrough_bios
);
2683 INIT_WORK(&cache
->migration_worker
, check_migrations
);
2684 INIT_DELAYED_WORK(&cache
->waker
, do_waker
);
2686 cache
->prison
= dm_bio_prison_create_v2(cache
->wq
);
2687 if (!cache
->prison
) {
2688 *error
= "could not create bio prison";
2692 cache
->migration_pool
= mempool_create_slab_pool(MIGRATION_POOL_SIZE
,
2694 if (!cache
->migration_pool
) {
2695 *error
= "Error creating cache's migration mempool";
2699 cache
->need_tick_bio
= true;
2700 cache
->sized
= false;
2701 cache
->invalidate
= false;
2702 cache
->commit_requested
= false;
2703 cache
->loaded_mappings
= false;
2704 cache
->loaded_discards
= false;
2708 atomic_set(&cache
->stats
.demotion
, 0);
2709 atomic_set(&cache
->stats
.promotion
, 0);
2710 atomic_set(&cache
->stats
.copies_avoided
, 0);
2711 atomic_set(&cache
->stats
.cache_cell_clash
, 0);
2712 atomic_set(&cache
->stats
.commit_count
, 0);
2713 atomic_set(&cache
->stats
.discard_count
, 0);
2715 spin_lock_init(&cache
->invalidation_lock
);
2716 INIT_LIST_HEAD(&cache
->invalidation_requests
);
2718 batcher_init(&cache
->committer
, commit_op
, cache
,
2719 issue_op
, cache
, cache
->wq
);
2720 iot_init(&cache
->origin_tracker
);
2722 init_rwsem(&cache
->background_work_lock
);
2723 prevent_background_work(cache
);
2732 static int copy_ctr_args(struct cache
*cache
, int argc
, const char **argv
)
2737 copy
= kcalloc(argc
, sizeof(*copy
), GFP_KERNEL
);
2740 for (i
= 0; i
< argc
; i
++) {
2741 copy
[i
] = kstrdup(argv
[i
], GFP_KERNEL
);
2750 cache
->nr_ctr_args
= argc
;
2751 cache
->ctr_args
= copy
;
2756 static int cache_ctr(struct dm_target
*ti
, unsigned argc
, char **argv
)
2759 struct cache_args
*ca
;
2760 struct cache
*cache
= NULL
;
2762 ca
= kzalloc(sizeof(*ca
), GFP_KERNEL
);
2764 ti
->error
= "Error allocating memory for cache";
2769 r
= parse_cache_args(ca
, argc
, argv
, &ti
->error
);
2773 r
= cache_create(ca
, &cache
);
2777 r
= copy_ctr_args(cache
, argc
- 3, (const char **)argv
+ 3);
2783 ti
->private = cache
;
2785 destroy_cache_args(ca
);
2789 /*----------------------------------------------------------------*/
2791 static int cache_map(struct dm_target
*ti
, struct bio
*bio
)
2793 struct cache
*cache
= ti
->private;
2797 dm_oblock_t block
= get_bio_block(cache
, bio
);
2798 size_t pb_data_size
= get_per_bio_data_size(cache
);
2800 init_per_bio_data(bio
, pb_data_size
);
2801 if (unlikely(from_oblock(block
) >= from_oblock(cache
->origin_blocks
))) {
2803 * This can only occur if the io goes to a partial block at
2804 * the end of the origin device. We don't cache these.
2805 * Just remap to the origin and carry on.
2807 remap_to_origin(cache
, bio
);
2808 accounted_begin(cache
, bio
);
2809 return DM_MAPIO_REMAPPED
;
2812 if (discard_or_flush(bio
)) {
2813 defer_bio(cache
, bio
);
2814 return DM_MAPIO_SUBMITTED
;
2817 r
= map_bio(cache
, bio
, block
, &commit_needed
);
2819 schedule_commit(&cache
->committer
);
2824 static int cache_end_io(struct dm_target
*ti
, struct bio
*bio
, int error
)
2826 struct cache
*cache
= ti
->private;
2827 unsigned long flags
;
2828 size_t pb_data_size
= get_per_bio_data_size(cache
);
2829 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
2832 policy_tick(cache
->policy
, false);
2834 spin_lock_irqsave(&cache
->lock
, flags
);
2835 cache
->need_tick_bio
= true;
2836 spin_unlock_irqrestore(&cache
->lock
, flags
);
2839 bio_drop_shared_lock(cache
, bio
);
2840 accounted_complete(cache
, bio
);
2845 static int write_dirty_bitset(struct cache
*cache
)
2849 if (get_cache_mode(cache
) >= CM_READ_ONLY
)
2852 r
= dm_cache_set_dirty_bits(cache
->cmd
, from_cblock(cache
->cache_size
), cache
->dirty_bitset
);
2854 metadata_operation_failed(cache
, "dm_cache_set_dirty_bits", r
);
2859 static int write_discard_bitset(struct cache
*cache
)
2863 if (get_cache_mode(cache
) >= CM_READ_ONLY
)
2866 r
= dm_cache_discard_bitset_resize(cache
->cmd
, cache
->discard_block_size
,
2867 cache
->discard_nr_blocks
);
2869 DMERR("%s: could not resize on-disk discard bitset", cache_device_name(cache
));
2870 metadata_operation_failed(cache
, "dm_cache_discard_bitset_resize", r
);
2874 for (i
= 0; i
< from_dblock(cache
->discard_nr_blocks
); i
++) {
2875 r
= dm_cache_set_discard(cache
->cmd
, to_dblock(i
),
2876 is_discarded(cache
, to_dblock(i
)));
2878 metadata_operation_failed(cache
, "dm_cache_set_discard", r
);
2886 static int write_hints(struct cache
*cache
)
2890 if (get_cache_mode(cache
) >= CM_READ_ONLY
)
2893 r
= dm_cache_write_hints(cache
->cmd
, cache
->policy
);
2895 metadata_operation_failed(cache
, "dm_cache_write_hints", r
);
2903 * returns true on success
2905 static bool sync_metadata(struct cache
*cache
)
2909 r1
= write_dirty_bitset(cache
);
2911 DMERR("%s: could not write dirty bitset", cache_device_name(cache
));
2913 r2
= write_discard_bitset(cache
);
2915 DMERR("%s: could not write discard bitset", cache_device_name(cache
));
2919 r3
= write_hints(cache
);
2921 DMERR("%s: could not write hints", cache_device_name(cache
));
2924 * If writing the above metadata failed, we still commit, but don't
2925 * set the clean shutdown flag. This will effectively force every
2926 * dirty bit to be set on reload.
2928 r4
= commit(cache
, !r1
&& !r2
&& !r3
);
2930 DMERR("%s: could not write cache metadata", cache_device_name(cache
));
2932 return !r1
&& !r2
&& !r3
&& !r4
;
2935 static void cache_postsuspend(struct dm_target
*ti
)
2937 struct cache
*cache
= ti
->private;
2939 prevent_background_work(cache
);
2940 BUG_ON(atomic_read(&cache
->nr_io_migrations
));
2942 cancel_delayed_work(&cache
->waker
);
2943 flush_workqueue(cache
->wq
);
2944 WARN_ON(cache
->origin_tracker
.in_flight
);
2947 * If it's a flush suspend there won't be any deferred bios, so this
2950 requeue_deferred_bios(cache
);
2952 if (get_cache_mode(cache
) == CM_WRITE
)
2953 (void) sync_metadata(cache
);
2956 static int load_mapping(void *context
, dm_oblock_t oblock
, dm_cblock_t cblock
,
2957 bool dirty
, uint32_t hint
, bool hint_valid
)
2960 struct cache
*cache
= context
;
2963 set_bit(from_cblock(cblock
), cache
->dirty_bitset
);
2964 atomic_inc(&cache
->nr_dirty
);
2966 clear_bit(from_cblock(cblock
), cache
->dirty_bitset
);
2968 r
= policy_load_mapping(cache
->policy
, oblock
, cblock
, dirty
, hint
, hint_valid
);
2976 * The discard block size in the on disk metadata is not
2977 * neccessarily the same as we're currently using. So we have to
2978 * be careful to only set the discarded attribute if we know it
2979 * covers a complete block of the new size.
2981 struct discard_load_info
{
2982 struct cache
*cache
;
2985 * These blocks are sized using the on disk dblock size, rather
2986 * than the current one.
2988 dm_block_t block_size
;
2989 dm_block_t discard_begin
, discard_end
;
2992 static void discard_load_info_init(struct cache
*cache
,
2993 struct discard_load_info
*li
)
2996 li
->discard_begin
= li
->discard_end
= 0;
2999 static void set_discard_range(struct discard_load_info
*li
)
3003 if (li
->discard_begin
== li
->discard_end
)
3007 * Convert to sectors.
3009 b
= li
->discard_begin
* li
->block_size
;
3010 e
= li
->discard_end
* li
->block_size
;
3013 * Then convert back to the current dblock size.
3015 b
= dm_sector_div_up(b
, li
->cache
->discard_block_size
);
3016 sector_div(e
, li
->cache
->discard_block_size
);
3019 * The origin may have shrunk, so we need to check we're still in
3022 if (e
> from_dblock(li
->cache
->discard_nr_blocks
))
3023 e
= from_dblock(li
->cache
->discard_nr_blocks
);
3026 set_discard(li
->cache
, to_dblock(b
));
3029 static int load_discard(void *context
, sector_t discard_block_size
,
3030 dm_dblock_t dblock
, bool discard
)
3032 struct discard_load_info
*li
= context
;
3034 li
->block_size
= discard_block_size
;
3037 if (from_dblock(dblock
) == li
->discard_end
)
3039 * We're already in a discard range, just extend it.
3041 li
->discard_end
= li
->discard_end
+ 1ULL;
3045 * Emit the old range and start a new one.
3047 set_discard_range(li
);
3048 li
->discard_begin
= from_dblock(dblock
);
3049 li
->discard_end
= li
->discard_begin
+ 1ULL;
3052 set_discard_range(li
);
3053 li
->discard_begin
= li
->discard_end
= 0;
3059 static dm_cblock_t
get_cache_dev_size(struct cache
*cache
)
3061 sector_t size
= get_dev_size(cache
->cache_dev
);
3062 (void) sector_div(size
, cache
->sectors_per_block
);
3063 return to_cblock(size
);
3066 static bool can_resize(struct cache
*cache
, dm_cblock_t new_size
)
3068 if (from_cblock(new_size
) > from_cblock(cache
->cache_size
))
3072 * We can't drop a dirty block when shrinking the cache.
3074 while (from_cblock(new_size
) < from_cblock(cache
->cache_size
)) {
3075 new_size
= to_cblock(from_cblock(new_size
) + 1);
3076 if (is_dirty(cache
, new_size
)) {
3077 DMERR("%s: unable to shrink cache; cache block %llu is dirty",
3078 cache_device_name(cache
),
3079 (unsigned long long) from_cblock(new_size
));
3087 static int resize_cache_dev(struct cache
*cache
, dm_cblock_t new_size
)
3091 r
= dm_cache_resize(cache
->cmd
, new_size
);
3093 DMERR("%s: could not resize cache metadata", cache_device_name(cache
));
3094 metadata_operation_failed(cache
, "dm_cache_resize", r
);
3098 set_cache_size(cache
, new_size
);
3103 static int cache_preresume(struct dm_target
*ti
)
3106 struct cache
*cache
= ti
->private;
3107 dm_cblock_t csize
= get_cache_dev_size(cache
);
3110 * Check to see if the cache has resized.
3112 if (!cache
->sized
) {
3113 r
= resize_cache_dev(cache
, csize
);
3117 cache
->sized
= true;
3119 } else if (csize
!= cache
->cache_size
) {
3120 if (!can_resize(cache
, csize
))
3123 r
= resize_cache_dev(cache
, csize
);
3128 if (!cache
->loaded_mappings
) {
3129 r
= dm_cache_load_mappings(cache
->cmd
, cache
->policy
,
3130 load_mapping
, cache
);
3132 DMERR("%s: could not load cache mappings", cache_device_name(cache
));
3133 metadata_operation_failed(cache
, "dm_cache_load_mappings", r
);
3137 cache
->loaded_mappings
= true;
3140 if (!cache
->loaded_discards
) {
3141 struct discard_load_info li
;
3144 * The discard bitset could have been resized, or the
3145 * discard block size changed. To be safe we start by
3146 * setting every dblock to not discarded.
3148 clear_bitset(cache
->discard_bitset
, from_dblock(cache
->discard_nr_blocks
));
3150 discard_load_info_init(cache
, &li
);
3151 r
= dm_cache_load_discards(cache
->cmd
, load_discard
, &li
);
3153 DMERR("%s: could not load origin discards", cache_device_name(cache
));
3154 metadata_operation_failed(cache
, "dm_cache_load_discards", r
);
3157 set_discard_range(&li
);
3159 cache
->loaded_discards
= true;
3165 static void cache_resume(struct dm_target
*ti
)
3167 struct cache
*cache
= ti
->private;
3169 cache
->need_tick_bio
= true;
3170 allow_background_work(cache
);
3171 do_waker(&cache
->waker
.work
);
3177 * <metadata block size> <#used metadata blocks>/<#total metadata blocks>
3178 * <cache block size> <#used cache blocks>/<#total cache blocks>
3179 * <#read hits> <#read misses> <#write hits> <#write misses>
3180 * <#demotions> <#promotions> <#dirty>
3181 * <#features> <features>*
3182 * <#core args> <core args>
3183 * <policy name> <#policy args> <policy args>* <cache metadata mode> <needs_check>
3185 static void cache_status(struct dm_target
*ti
, status_type_t type
,
3186 unsigned status_flags
, char *result
, unsigned maxlen
)
3191 dm_block_t nr_free_blocks_metadata
= 0;
3192 dm_block_t nr_blocks_metadata
= 0;
3193 char buf
[BDEVNAME_SIZE
];
3194 struct cache
*cache
= ti
->private;
3195 dm_cblock_t residency
;
3199 case STATUSTYPE_INFO
:
3200 if (get_cache_mode(cache
) == CM_FAIL
) {
3205 /* Commit to ensure statistics aren't out-of-date */
3206 if (!(status_flags
& DM_STATUS_NOFLUSH_FLAG
) && !dm_suspended(ti
))
3207 (void) commit(cache
, false);
3209 r
= dm_cache_get_free_metadata_block_count(cache
->cmd
, &nr_free_blocks_metadata
);
3211 DMERR("%s: dm_cache_get_free_metadata_block_count returned %d",
3212 cache_device_name(cache
), r
);
3216 r
= dm_cache_get_metadata_dev_size(cache
->cmd
, &nr_blocks_metadata
);
3218 DMERR("%s: dm_cache_get_metadata_dev_size returned %d",
3219 cache_device_name(cache
), r
);
3223 residency
= policy_residency(cache
->policy
);
3225 DMEMIT("%u %llu/%llu %llu %llu/%llu %u %u %u %u %u %u %lu ",
3226 (unsigned)DM_CACHE_METADATA_BLOCK_SIZE
,
3227 (unsigned long long)(nr_blocks_metadata
- nr_free_blocks_metadata
),
3228 (unsigned long long)nr_blocks_metadata
,
3229 (unsigned long long)cache
->sectors_per_block
,
3230 (unsigned long long) from_cblock(residency
),
3231 (unsigned long long) from_cblock(cache
->cache_size
),
3232 (unsigned) atomic_read(&cache
->stats
.read_hit
),
3233 (unsigned) atomic_read(&cache
->stats
.read_miss
),
3234 (unsigned) atomic_read(&cache
->stats
.write_hit
),
3235 (unsigned) atomic_read(&cache
->stats
.write_miss
),
3236 (unsigned) atomic_read(&cache
->stats
.demotion
),
3237 (unsigned) atomic_read(&cache
->stats
.promotion
),
3238 (unsigned long) atomic_read(&cache
->nr_dirty
));
3240 if (cache
->features
.metadata_version
== 2)
3241 DMEMIT("2 metadata2 ");
3245 if (writethrough_mode(&cache
->features
))
3246 DMEMIT("writethrough ");
3248 else if (passthrough_mode(&cache
->features
))
3249 DMEMIT("passthrough ");
3251 else if (writeback_mode(&cache
->features
))
3252 DMEMIT("writeback ");
3255 DMERR("%s: internal error: unknown io mode: %d",
3256 cache_device_name(cache
), (int) cache
->features
.io_mode
);
3260 DMEMIT("2 migration_threshold %llu ", (unsigned long long) cache
->migration_threshold
);
3262 DMEMIT("%s ", dm_cache_policy_get_name(cache
->policy
));
3264 r
= policy_emit_config_values(cache
->policy
, result
, maxlen
, &sz
);
3266 DMERR("%s: policy_emit_config_values returned %d",
3267 cache_device_name(cache
), r
);
3270 if (get_cache_mode(cache
) == CM_READ_ONLY
)
3275 r
= dm_cache_metadata_needs_check(cache
->cmd
, &needs_check
);
3277 if (r
|| needs_check
)
3278 DMEMIT("needs_check ");
3284 case STATUSTYPE_TABLE
:
3285 format_dev_t(buf
, cache
->metadata_dev
->bdev
->bd_dev
);
3287 format_dev_t(buf
, cache
->cache_dev
->bdev
->bd_dev
);
3289 format_dev_t(buf
, cache
->origin_dev
->bdev
->bd_dev
);
3292 for (i
= 0; i
< cache
->nr_ctr_args
- 1; i
++)
3293 DMEMIT(" %s", cache
->ctr_args
[i
]);
3294 if (cache
->nr_ctr_args
)
3295 DMEMIT(" %s", cache
->ctr_args
[cache
->nr_ctr_args
- 1]);
3305 * Defines a range of cblocks, begin to (end - 1) are in the range. end is
3306 * the one-past-the-end value.
3308 struct cblock_range
{
3314 * A cache block range can take two forms:
3316 * i) A single cblock, eg. '3456'
3317 * ii) A begin and end cblock with a dash between, eg. 123-234
3319 static int parse_cblock_range(struct cache
*cache
, const char *str
,
3320 struct cblock_range
*result
)
3327 * Try and parse form (ii) first.
3329 r
= sscanf(str
, "%llu-%llu%c", &b
, &e
, &dummy
);
3334 result
->begin
= to_cblock(b
);
3335 result
->end
= to_cblock(e
);
3340 * That didn't work, try form (i).
3342 r
= sscanf(str
, "%llu%c", &b
, &dummy
);
3347 result
->begin
= to_cblock(b
);
3348 result
->end
= to_cblock(from_cblock(result
->begin
) + 1u);
3352 DMERR("%s: invalid cblock range '%s'", cache_device_name(cache
), str
);
3356 static int validate_cblock_range(struct cache
*cache
, struct cblock_range
*range
)
3358 uint64_t b
= from_cblock(range
->begin
);
3359 uint64_t e
= from_cblock(range
->end
);
3360 uint64_t n
= from_cblock(cache
->cache_size
);
3363 DMERR("%s: begin cblock out of range: %llu >= %llu",
3364 cache_device_name(cache
), b
, n
);
3369 DMERR("%s: end cblock out of range: %llu > %llu",
3370 cache_device_name(cache
), e
, n
);
3375 DMERR("%s: invalid cblock range: %llu >= %llu",
3376 cache_device_name(cache
), b
, e
);
3383 static inline dm_cblock_t
cblock_succ(dm_cblock_t b
)
3385 return to_cblock(from_cblock(b
) + 1);
3388 static int request_invalidation(struct cache
*cache
, struct cblock_range
*range
)
3393 * We don't need to do any locking here because we know we're in
3394 * passthrough mode. There's is potential for a race between an
3395 * invalidation triggered by an io and an invalidation message. This
3396 * is harmless, we must not worry if the policy call fails.
3398 while (range
->begin
!= range
->end
) {
3399 r
= invalidate_cblock(cache
, range
->begin
);
3403 range
->begin
= cblock_succ(range
->begin
);
3406 cache
->commit_requested
= true;
3410 static int process_invalidate_cblocks_message(struct cache
*cache
, unsigned count
,
3411 const char **cblock_ranges
)
3415 struct cblock_range range
;
3417 if (!passthrough_mode(&cache
->features
)) {
3418 DMERR("%s: cache has to be in passthrough mode for invalidation",
3419 cache_device_name(cache
));
3423 for (i
= 0; i
< count
; i
++) {
3424 r
= parse_cblock_range(cache
, cblock_ranges
[i
], &range
);
3428 r
= validate_cblock_range(cache
, &range
);
3433 * Pass begin and end origin blocks to the worker and wake it.
3435 r
= request_invalidation(cache
, &range
);
3447 * "invalidate_cblocks [(<begin>)|(<begin>-<end>)]*
3449 * The key migration_threshold is supported by the cache target core.
3451 static int cache_message(struct dm_target
*ti
, unsigned argc
, char **argv
)
3453 struct cache
*cache
= ti
->private;
3458 if (get_cache_mode(cache
) >= CM_READ_ONLY
) {
3459 DMERR("%s: unable to service cache target messages in READ_ONLY or FAIL mode",
3460 cache_device_name(cache
));
3464 if (!strcasecmp(argv
[0], "invalidate_cblocks"))
3465 return process_invalidate_cblocks_message(cache
, argc
- 1, (const char **) argv
+ 1);
3470 return set_config_value(cache
, argv
[0], argv
[1]);
3473 static int cache_iterate_devices(struct dm_target
*ti
,
3474 iterate_devices_callout_fn fn
, void *data
)
3477 struct cache
*cache
= ti
->private;
3479 r
= fn(ti
, cache
->cache_dev
, 0, get_dev_size(cache
->cache_dev
), data
);
3481 r
= fn(ti
, cache
->origin_dev
, 0, ti
->len
, data
);
3486 static void set_discard_limits(struct cache
*cache
, struct queue_limits
*limits
)
3489 * FIXME: these limits may be incompatible with the cache device
3491 limits
->max_discard_sectors
= min_t(sector_t
, cache
->discard_block_size
* 1024,
3492 cache
->origin_sectors
);
3493 limits
->discard_granularity
= cache
->discard_block_size
<< SECTOR_SHIFT
;
3496 static void cache_io_hints(struct dm_target
*ti
, struct queue_limits
*limits
)
3498 struct cache
*cache
= ti
->private;
3499 uint64_t io_opt_sectors
= limits
->io_opt
>> SECTOR_SHIFT
;
3502 * If the system-determined stacked limits are compatible with the
3503 * cache's blocksize (io_opt is a factor) do not override them.
3505 if (io_opt_sectors
< cache
->sectors_per_block
||
3506 do_div(io_opt_sectors
, cache
->sectors_per_block
)) {
3507 blk_limits_io_min(limits
, cache
->sectors_per_block
<< SECTOR_SHIFT
);
3508 blk_limits_io_opt(limits
, cache
->sectors_per_block
<< SECTOR_SHIFT
);
3510 set_discard_limits(cache
, limits
);
3513 /*----------------------------------------------------------------*/
3515 static struct target_type cache_target
= {
3517 .version
= {2, 0, 0},
3518 .module
= THIS_MODULE
,
3522 .end_io
= cache_end_io
,
3523 .postsuspend
= cache_postsuspend
,
3524 .preresume
= cache_preresume
,
3525 .resume
= cache_resume
,
3526 .status
= cache_status
,
3527 .message
= cache_message
,
3528 .iterate_devices
= cache_iterate_devices
,
3529 .io_hints
= cache_io_hints
,
3532 static int __init
dm_cache_init(void)
3536 r
= dm_register_target(&cache_target
);
3538 DMERR("cache target registration failed: %d", r
);
3542 migration_cache
= KMEM_CACHE(dm_cache_migration
, 0);
3543 if (!migration_cache
) {
3544 dm_unregister_target(&cache_target
);
3551 static void __exit
dm_cache_exit(void)
3553 dm_unregister_target(&cache_target
);
3554 kmem_cache_destroy(migration_cache
);
3557 module_init(dm_cache_init
);
3558 module_exit(dm_cache_exit
);
3560 MODULE_DESCRIPTION(DM_NAME
" cache target");
3561 MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
3562 MODULE_LICENSE("GPL");