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
)
100 iot
->in_flight
-= len
;
102 iot
->idle_time
= jiffies
;
105 static void iot_io_end(struct io_tracker
*iot
, sector_t len
)
109 spin_lock_irqsave(&iot
->lock
, flags
);
110 __iot_io_end(iot
, len
);
111 spin_unlock_irqrestore(&iot
->lock
, flags
);
114 /*----------------------------------------------------------------*/
117 * Represents a chunk of future work. 'input' allows continuations to pass
118 * values between themselves, typically error values.
120 struct continuation
{
121 struct work_struct ws
;
125 static inline void init_continuation(struct continuation
*k
,
126 void (*fn
)(struct work_struct
*))
128 INIT_WORK(&k
->ws
, fn
);
132 static inline void queue_continuation(struct workqueue_struct
*wq
,
133 struct continuation
*k
)
135 queue_work(wq
, &k
->ws
);
138 /*----------------------------------------------------------------*/
141 * The batcher collects together pieces of work that need a particular
142 * operation to occur before they can proceed (typically a commit).
146 * The operation that everyone is waiting for.
148 blk_status_t (*commit_op
)(void *context
);
149 void *commit_context
;
152 * This is how bios should be issued once the commit op is complete
153 * (accounted_request).
155 void (*issue_op
)(struct bio
*bio
, void *context
);
159 * Queued work gets put on here after commit.
161 struct workqueue_struct
*wq
;
164 struct list_head work_items
;
165 struct bio_list bios
;
166 struct work_struct commit_work
;
168 bool commit_scheduled
;
171 static void __commit(struct work_struct
*_ws
)
173 struct batcher
*b
= container_of(_ws
, struct batcher
, commit_work
);
176 struct list_head work_items
;
177 struct work_struct
*ws
, *tmp
;
178 struct continuation
*k
;
180 struct bio_list bios
;
182 INIT_LIST_HEAD(&work_items
);
183 bio_list_init(&bios
);
186 * We have to grab these before the commit_op to avoid a race
189 spin_lock_irqsave(&b
->lock
, flags
);
190 list_splice_init(&b
->work_items
, &work_items
);
191 bio_list_merge(&bios
, &b
->bios
);
192 bio_list_init(&b
->bios
);
193 b
->commit_scheduled
= false;
194 spin_unlock_irqrestore(&b
->lock
, flags
);
196 r
= b
->commit_op(b
->commit_context
);
198 list_for_each_entry_safe(ws
, tmp
, &work_items
, entry
) {
199 k
= container_of(ws
, struct continuation
, ws
);
201 INIT_LIST_HEAD(&ws
->entry
); /* to avoid a WARN_ON */
202 queue_work(b
->wq
, ws
);
205 while ((bio
= bio_list_pop(&bios
))) {
210 b
->issue_op(bio
, b
->issue_context
);
214 static void batcher_init(struct batcher
*b
,
215 blk_status_t (*commit_op
)(void *),
216 void *commit_context
,
217 void (*issue_op
)(struct bio
*bio
, void *),
219 struct workqueue_struct
*wq
)
221 b
->commit_op
= commit_op
;
222 b
->commit_context
= commit_context
;
223 b
->issue_op
= issue_op
;
224 b
->issue_context
= issue_context
;
227 spin_lock_init(&b
->lock
);
228 INIT_LIST_HEAD(&b
->work_items
);
229 bio_list_init(&b
->bios
);
230 INIT_WORK(&b
->commit_work
, __commit
);
231 b
->commit_scheduled
= false;
234 static void async_commit(struct batcher
*b
)
236 queue_work(b
->wq
, &b
->commit_work
);
239 static void continue_after_commit(struct batcher
*b
, struct continuation
*k
)
242 bool commit_scheduled
;
244 spin_lock_irqsave(&b
->lock
, flags
);
245 commit_scheduled
= b
->commit_scheduled
;
246 list_add_tail(&k
->ws
.entry
, &b
->work_items
);
247 spin_unlock_irqrestore(&b
->lock
, flags
);
249 if (commit_scheduled
)
254 * Bios are errored if commit failed.
256 static void issue_after_commit(struct batcher
*b
, struct bio
*bio
)
259 bool commit_scheduled
;
261 spin_lock_irqsave(&b
->lock
, flags
);
262 commit_scheduled
= b
->commit_scheduled
;
263 bio_list_add(&b
->bios
, bio
);
264 spin_unlock_irqrestore(&b
->lock
, flags
);
266 if (commit_scheduled
)
271 * Call this if some urgent work is waiting for the commit to complete.
273 static void schedule_commit(struct batcher
*b
)
278 spin_lock_irqsave(&b
->lock
, flags
);
279 immediate
= !list_empty(&b
->work_items
) || !bio_list_empty(&b
->bios
);
280 b
->commit_scheduled
= true;
281 spin_unlock_irqrestore(&b
->lock
, flags
);
288 * There are a couple of places where we let a bio run, but want to do some
289 * work before calling its endio function. We do this by temporarily
290 * changing the endio fn.
292 struct dm_hook_info
{
293 bio_end_io_t
*bi_end_io
;
296 static void dm_hook_bio(struct dm_hook_info
*h
, struct bio
*bio
,
297 bio_end_io_t
*bi_end_io
, void *bi_private
)
299 h
->bi_end_io
= bio
->bi_end_io
;
301 bio
->bi_end_io
= bi_end_io
;
302 bio
->bi_private
= bi_private
;
305 static void dm_unhook_bio(struct dm_hook_info
*h
, struct bio
*bio
)
307 bio
->bi_end_io
= h
->bi_end_io
;
310 /*----------------------------------------------------------------*/
312 #define MIGRATION_POOL_SIZE 128
313 #define COMMIT_PERIOD HZ
314 #define MIGRATION_COUNT_WINDOW 10
317 * The block size of the device holding cache data must be
318 * between 32KB and 1GB.
320 #define DATA_DEV_BLOCK_SIZE_MIN_SECTORS (32 * 1024 >> SECTOR_SHIFT)
321 #define DATA_DEV_BLOCK_SIZE_MAX_SECTORS (1024 * 1024 * 1024 >> SECTOR_SHIFT)
323 enum cache_metadata_mode
{
324 CM_WRITE
, /* metadata may be changed */
325 CM_READ_ONLY
, /* metadata may not be changed */
331 * Data is written to cached blocks only. These blocks are marked
332 * dirty. If you lose the cache device you will lose data.
333 * Potential performance increase for both reads and writes.
338 * Data is written to both cache and origin. Blocks are never
339 * dirty. Potential performance benfit for reads only.
344 * A degraded mode useful for various cache coherency situations
345 * (eg, rolling back snapshots). Reads and writes always go to the
346 * origin. If a write goes to a cached oblock, then the cache
347 * block is invalidated.
352 struct cache_features
{
353 enum cache_metadata_mode mode
;
354 enum cache_io_mode io_mode
;
355 unsigned metadata_version
;
366 atomic_t copies_avoided
;
367 atomic_t cache_cell_clash
;
368 atomic_t commit_count
;
369 atomic_t discard_count
;
373 struct dm_target
*ti
;
374 struct dm_target_callbacks callbacks
;
376 struct dm_cache_metadata
*cmd
;
379 * Metadata is written to this device.
381 struct dm_dev
*metadata_dev
;
384 * The slower of the two data devices. Typically a spindle.
386 struct dm_dev
*origin_dev
;
389 * The faster of the two data devices. Typically an SSD.
391 struct dm_dev
*cache_dev
;
394 * Size of the origin device in _complete_ blocks and native sectors.
396 dm_oblock_t origin_blocks
;
397 sector_t origin_sectors
;
400 * Size of the cache device in blocks.
402 dm_cblock_t cache_size
;
405 * Fields for converting from sectors to blocks.
407 sector_t sectors_per_block
;
408 int sectors_per_block_shift
;
411 struct list_head deferred_cells
;
412 struct bio_list deferred_bios
;
413 struct bio_list deferred_writethrough_bios
;
414 sector_t migration_threshold
;
415 wait_queue_head_t migration_wait
;
416 atomic_t nr_allocated_migrations
;
419 * The number of in flight migrations that are performing
420 * background io. eg, promotion, writeback.
422 atomic_t nr_io_migrations
;
424 struct rw_semaphore quiesce_lock
;
427 * cache_size entries, dirty if set
430 unsigned long *dirty_bitset
;
433 * origin_blocks entries, discarded if set.
435 dm_dblock_t discard_nr_blocks
;
436 unsigned long *discard_bitset
;
437 uint32_t discard_block_size
; /* a power of 2 times sectors per block */
440 * Rather than reconstructing the table line for the status we just
441 * save it and regurgitate.
443 unsigned nr_ctr_args
;
444 const char **ctr_args
;
446 struct dm_kcopyd_client
*copier
;
447 struct workqueue_struct
*wq
;
448 struct work_struct deferred_bio_worker
;
449 struct work_struct deferred_writethrough_worker
;
450 struct work_struct migration_worker
;
451 struct delayed_work waker
;
452 struct dm_bio_prison_v2
*prison
;
454 mempool_t
*migration_pool
;
456 struct dm_cache_policy
*policy
;
457 unsigned policy_nr_args
;
459 bool need_tick_bio
:1;
462 bool commit_requested
:1;
463 bool loaded_mappings
:1;
464 bool loaded_discards
:1;
467 * Cache features such as write-through.
469 struct cache_features features
;
471 struct cache_stats stats
;
474 * Invalidation fields.
476 spinlock_t invalidation_lock
;
477 struct list_head invalidation_requests
;
479 struct io_tracker tracker
;
481 struct work_struct commit_ws
;
482 struct batcher committer
;
484 struct rw_semaphore background_work_lock
;
487 struct per_bio_data
{
490 struct dm_bio_prison_cell_v2
*cell
;
491 struct dm_hook_info hook_info
;
495 * writethrough fields. These MUST remain at the end of this
496 * structure and the 'cache' member must be the first as it
497 * is used to determine the offset of the writethrough fields.
501 struct dm_bio_details bio_details
;
504 struct dm_cache_migration
{
505 struct continuation k
;
508 struct policy_work
*op
;
509 struct bio
*overwrite_bio
;
510 struct dm_bio_prison_cell_v2
*cell
;
512 dm_cblock_t invalidate_cblock
;
513 dm_oblock_t invalidate_oblock
;
516 /*----------------------------------------------------------------*/
518 static bool writethrough_mode(struct cache_features
*f
)
520 return f
->io_mode
== CM_IO_WRITETHROUGH
;
523 static bool writeback_mode(struct cache_features
*f
)
525 return f
->io_mode
== CM_IO_WRITEBACK
;
528 static inline bool passthrough_mode(struct cache_features
*f
)
530 return unlikely(f
->io_mode
== CM_IO_PASSTHROUGH
);
533 /*----------------------------------------------------------------*/
535 static void wake_deferred_bio_worker(struct cache
*cache
)
537 queue_work(cache
->wq
, &cache
->deferred_bio_worker
);
540 static void wake_deferred_writethrough_worker(struct cache
*cache
)
542 queue_work(cache
->wq
, &cache
->deferred_writethrough_worker
);
545 static void wake_migration_worker(struct cache
*cache
)
547 if (passthrough_mode(&cache
->features
))
550 queue_work(cache
->wq
, &cache
->migration_worker
);
553 /*----------------------------------------------------------------*/
555 static struct dm_bio_prison_cell_v2
*alloc_prison_cell(struct cache
*cache
)
557 return dm_bio_prison_alloc_cell_v2(cache
->prison
, GFP_NOWAIT
);
560 static void free_prison_cell(struct cache
*cache
, struct dm_bio_prison_cell_v2
*cell
)
562 dm_bio_prison_free_cell_v2(cache
->prison
, cell
);
565 static struct dm_cache_migration
*alloc_migration(struct cache
*cache
)
567 struct dm_cache_migration
*mg
;
569 mg
= mempool_alloc(cache
->migration_pool
, GFP_NOWAIT
);
572 atomic_inc(&mg
->cache
->nr_allocated_migrations
);
578 static void free_migration(struct dm_cache_migration
*mg
)
580 struct cache
*cache
= mg
->cache
;
582 if (atomic_dec_and_test(&cache
->nr_allocated_migrations
))
583 wake_up(&cache
->migration_wait
);
585 mempool_free(mg
, cache
->migration_pool
);
588 /*----------------------------------------------------------------*/
590 static inline dm_oblock_t
oblock_succ(dm_oblock_t b
)
592 return to_oblock(from_oblock(b
) + 1ull);
595 static void build_key(dm_oblock_t begin
, dm_oblock_t end
, struct dm_cell_key_v2
*key
)
599 key
->block_begin
= from_oblock(begin
);
600 key
->block_end
= from_oblock(end
);
604 * We have two lock levels. Level 0, which is used to prevent WRITEs, and
605 * level 1 which prevents *both* READs and WRITEs.
607 #define WRITE_LOCK_LEVEL 0
608 #define READ_WRITE_LOCK_LEVEL 1
610 static unsigned lock_level(struct bio
*bio
)
612 return bio_data_dir(bio
) == WRITE
?
614 READ_WRITE_LOCK_LEVEL
;
617 /*----------------------------------------------------------------
619 *--------------------------------------------------------------*/
622 * If using writeback, leave out struct per_bio_data's writethrough fields.
624 #define PB_DATA_SIZE_WB (offsetof(struct per_bio_data, cache))
625 #define PB_DATA_SIZE_WT (sizeof(struct per_bio_data))
627 static size_t get_per_bio_data_size(struct cache
*cache
)
629 return writethrough_mode(&cache
->features
) ? PB_DATA_SIZE_WT
: PB_DATA_SIZE_WB
;
632 static struct per_bio_data
*get_per_bio_data(struct bio
*bio
, size_t data_size
)
634 struct per_bio_data
*pb
= dm_per_bio_data(bio
, data_size
);
639 static struct per_bio_data
*init_per_bio_data(struct bio
*bio
, size_t data_size
)
641 struct per_bio_data
*pb
= get_per_bio_data(bio
, data_size
);
644 pb
->req_nr
= dm_bio_get_target_bio_nr(bio
);
651 /*----------------------------------------------------------------*/
653 static void defer_bio(struct cache
*cache
, struct bio
*bio
)
657 spin_lock_irqsave(&cache
->lock
, flags
);
658 bio_list_add(&cache
->deferred_bios
, bio
);
659 spin_unlock_irqrestore(&cache
->lock
, flags
);
661 wake_deferred_bio_worker(cache
);
664 static void defer_bios(struct cache
*cache
, struct bio_list
*bios
)
668 spin_lock_irqsave(&cache
->lock
, flags
);
669 bio_list_merge(&cache
->deferred_bios
, bios
);
671 spin_unlock_irqrestore(&cache
->lock
, flags
);
673 wake_deferred_bio_worker(cache
);
676 /*----------------------------------------------------------------*/
678 static bool bio_detain_shared(struct cache
*cache
, dm_oblock_t oblock
, struct bio
*bio
)
682 struct per_bio_data
*pb
;
683 struct dm_cell_key_v2 key
;
684 dm_oblock_t end
= to_oblock(from_oblock(oblock
) + 1ULL);
685 struct dm_bio_prison_cell_v2
*cell_prealloc
, *cell
;
687 cell_prealloc
= alloc_prison_cell(cache
); /* FIXME: allow wait if calling from worker */
688 if (!cell_prealloc
) {
689 defer_bio(cache
, bio
);
693 build_key(oblock
, end
, &key
);
694 r
= dm_cell_get_v2(cache
->prison
, &key
, lock_level(bio
), bio
, cell_prealloc
, &cell
);
697 * Failed to get the lock.
699 free_prison_cell(cache
, cell_prealloc
);
703 if (cell
!= cell_prealloc
)
704 free_prison_cell(cache
, cell_prealloc
);
706 pb_size
= get_per_bio_data_size(cache
);
707 pb
= get_per_bio_data(bio
, pb_size
);
713 /*----------------------------------------------------------------*/
715 static bool is_dirty(struct cache
*cache
, dm_cblock_t b
)
717 return test_bit(from_cblock(b
), cache
->dirty_bitset
);
720 static void set_dirty(struct cache
*cache
, dm_cblock_t cblock
)
722 if (!test_and_set_bit(from_cblock(cblock
), cache
->dirty_bitset
)) {
723 atomic_inc(&cache
->nr_dirty
);
724 policy_set_dirty(cache
->policy
, cblock
);
729 * These two are called when setting after migrations to force the policy
730 * and dirty bitset to be in sync.
732 static void force_set_dirty(struct cache
*cache
, dm_cblock_t cblock
)
734 if (!test_and_set_bit(from_cblock(cblock
), cache
->dirty_bitset
))
735 atomic_inc(&cache
->nr_dirty
);
736 policy_set_dirty(cache
->policy
, cblock
);
739 static void force_clear_dirty(struct cache
*cache
, dm_cblock_t cblock
)
741 if (test_and_clear_bit(from_cblock(cblock
), cache
->dirty_bitset
)) {
742 if (atomic_dec_return(&cache
->nr_dirty
) == 0)
743 dm_table_event(cache
->ti
->table
);
746 policy_clear_dirty(cache
->policy
, cblock
);
749 /*----------------------------------------------------------------*/
751 static bool block_size_is_power_of_two(struct cache
*cache
)
753 return cache
->sectors_per_block_shift
>= 0;
756 /* gcc on ARM generates spurious references to __udivdi3 and __umoddi3 */
757 #if defined(CONFIG_ARM) && __GNUC__ == 4 && __GNUC_MINOR__ <= 6
760 static dm_block_t
block_div(dm_block_t b
, uint32_t n
)
767 static dm_block_t
oblocks_per_dblock(struct cache
*cache
)
769 dm_block_t oblocks
= cache
->discard_block_size
;
771 if (block_size_is_power_of_two(cache
))
772 oblocks
>>= cache
->sectors_per_block_shift
;
774 oblocks
= block_div(oblocks
, cache
->sectors_per_block
);
779 static dm_dblock_t
oblock_to_dblock(struct cache
*cache
, dm_oblock_t oblock
)
781 return to_dblock(block_div(from_oblock(oblock
),
782 oblocks_per_dblock(cache
)));
785 static void set_discard(struct cache
*cache
, dm_dblock_t b
)
789 BUG_ON(from_dblock(b
) >= from_dblock(cache
->discard_nr_blocks
));
790 atomic_inc(&cache
->stats
.discard_count
);
792 spin_lock_irqsave(&cache
->lock
, flags
);
793 set_bit(from_dblock(b
), cache
->discard_bitset
);
794 spin_unlock_irqrestore(&cache
->lock
, flags
);
797 static void clear_discard(struct cache
*cache
, dm_dblock_t b
)
801 spin_lock_irqsave(&cache
->lock
, flags
);
802 clear_bit(from_dblock(b
), cache
->discard_bitset
);
803 spin_unlock_irqrestore(&cache
->lock
, flags
);
806 static bool is_discarded(struct cache
*cache
, dm_dblock_t b
)
811 spin_lock_irqsave(&cache
->lock
, flags
);
812 r
= test_bit(from_dblock(b
), cache
->discard_bitset
);
813 spin_unlock_irqrestore(&cache
->lock
, flags
);
818 static bool is_discarded_oblock(struct cache
*cache
, dm_oblock_t b
)
823 spin_lock_irqsave(&cache
->lock
, flags
);
824 r
= test_bit(from_dblock(oblock_to_dblock(cache
, b
)),
825 cache
->discard_bitset
);
826 spin_unlock_irqrestore(&cache
->lock
, flags
);
831 /*----------------------------------------------------------------
833 *--------------------------------------------------------------*/
834 static void remap_to_origin(struct cache
*cache
, struct bio
*bio
)
836 bio
->bi_bdev
= cache
->origin_dev
->bdev
;
839 static void remap_to_cache(struct cache
*cache
, struct bio
*bio
,
842 sector_t bi_sector
= bio
->bi_iter
.bi_sector
;
843 sector_t block
= from_cblock(cblock
);
845 bio
->bi_bdev
= cache
->cache_dev
->bdev
;
846 if (!block_size_is_power_of_two(cache
))
847 bio
->bi_iter
.bi_sector
=
848 (block
* cache
->sectors_per_block
) +
849 sector_div(bi_sector
, cache
->sectors_per_block
);
851 bio
->bi_iter
.bi_sector
=
852 (block
<< cache
->sectors_per_block_shift
) |
853 (bi_sector
& (cache
->sectors_per_block
- 1));
856 static void check_if_tick_bio_needed(struct cache
*cache
, struct bio
*bio
)
859 size_t pb_data_size
= get_per_bio_data_size(cache
);
860 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
862 spin_lock_irqsave(&cache
->lock
, flags
);
863 if (cache
->need_tick_bio
&& !op_is_flush(bio
->bi_opf
) &&
864 bio_op(bio
) != REQ_OP_DISCARD
) {
866 cache
->need_tick_bio
= false;
868 spin_unlock_irqrestore(&cache
->lock
, flags
);
871 static void remap_to_origin_clear_discard(struct cache
*cache
, struct bio
*bio
,
874 // FIXME: this is called way too much.
875 check_if_tick_bio_needed(cache
, bio
);
876 remap_to_origin(cache
, bio
);
877 if (bio_data_dir(bio
) == WRITE
)
878 clear_discard(cache
, oblock_to_dblock(cache
, oblock
));
881 static void remap_to_cache_dirty(struct cache
*cache
, struct bio
*bio
,
882 dm_oblock_t oblock
, dm_cblock_t cblock
)
884 check_if_tick_bio_needed(cache
, bio
);
885 remap_to_cache(cache
, bio
, cblock
);
886 if (bio_data_dir(bio
) == WRITE
) {
887 set_dirty(cache
, cblock
);
888 clear_discard(cache
, oblock_to_dblock(cache
, oblock
));
892 static dm_oblock_t
get_bio_block(struct cache
*cache
, struct bio
*bio
)
894 sector_t block_nr
= bio
->bi_iter
.bi_sector
;
896 if (!block_size_is_power_of_two(cache
))
897 (void) sector_div(block_nr
, cache
->sectors_per_block
);
899 block_nr
>>= cache
->sectors_per_block_shift
;
901 return to_oblock(block_nr
);
904 static bool accountable_bio(struct cache
*cache
, struct bio
*bio
)
906 return bio_op(bio
) != REQ_OP_DISCARD
;
909 static void accounted_begin(struct cache
*cache
, struct bio
*bio
)
911 size_t pb_data_size
= get_per_bio_data_size(cache
);
912 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
914 if (accountable_bio(cache
, bio
)) {
915 pb
->len
= bio_sectors(bio
);
916 iot_io_begin(&cache
->tracker
, pb
->len
);
920 static void accounted_complete(struct cache
*cache
, struct bio
*bio
)
922 size_t pb_data_size
= get_per_bio_data_size(cache
);
923 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
925 iot_io_end(&cache
->tracker
, pb
->len
);
928 static void accounted_request(struct cache
*cache
, struct bio
*bio
)
930 accounted_begin(cache
, bio
);
931 generic_make_request(bio
);
934 static void issue_op(struct bio
*bio
, void *context
)
936 struct cache
*cache
= context
;
937 accounted_request(cache
, bio
);
940 static void defer_writethrough_bio(struct cache
*cache
, struct bio
*bio
)
944 spin_lock_irqsave(&cache
->lock
, flags
);
945 bio_list_add(&cache
->deferred_writethrough_bios
, bio
);
946 spin_unlock_irqrestore(&cache
->lock
, flags
);
948 wake_deferred_writethrough_worker(cache
);
951 static void writethrough_endio(struct bio
*bio
)
953 struct per_bio_data
*pb
= get_per_bio_data(bio
, PB_DATA_SIZE_WT
);
955 dm_unhook_bio(&pb
->hook_info
, bio
);
957 if (bio
->bi_status
) {
962 dm_bio_restore(&pb
->bio_details
, bio
);
963 remap_to_cache(pb
->cache
, bio
, pb
->cblock
);
966 * We can't issue this bio directly, since we're in interrupt
967 * context. So it gets put on a bio list for processing by the
970 defer_writethrough_bio(pb
->cache
, bio
);
974 * FIXME: send in parallel, huge latency as is.
975 * When running in writethrough mode we need to send writes to clean blocks
976 * to both the cache and origin devices. In future we'd like to clone the
977 * bio and send them in parallel, but for now we're doing them in
978 * series as this is easier.
980 static void remap_to_origin_then_cache(struct cache
*cache
, struct bio
*bio
,
981 dm_oblock_t oblock
, dm_cblock_t cblock
)
983 struct per_bio_data
*pb
= get_per_bio_data(bio
, PB_DATA_SIZE_WT
);
987 dm_hook_bio(&pb
->hook_info
, bio
, writethrough_endio
, NULL
);
988 dm_bio_record(&pb
->bio_details
, bio
);
990 remap_to_origin_clear_discard(pb
->cache
, bio
, oblock
);
993 /*----------------------------------------------------------------
995 *--------------------------------------------------------------*/
996 static enum cache_metadata_mode
get_cache_mode(struct cache
*cache
)
998 return cache
->features
.mode
;
1001 static const char *cache_device_name(struct cache
*cache
)
1003 return dm_device_name(dm_table_get_md(cache
->ti
->table
));
1006 static void notify_mode_switch(struct cache
*cache
, enum cache_metadata_mode mode
)
1008 const char *descs
[] = {
1014 dm_table_event(cache
->ti
->table
);
1015 DMINFO("%s: switching cache to %s mode",
1016 cache_device_name(cache
), descs
[(int)mode
]);
1019 static void set_cache_mode(struct cache
*cache
, enum cache_metadata_mode new_mode
)
1022 enum cache_metadata_mode old_mode
= get_cache_mode(cache
);
1024 if (dm_cache_metadata_needs_check(cache
->cmd
, &needs_check
)) {
1025 DMERR("%s: unable to read needs_check flag, setting failure mode.",
1026 cache_device_name(cache
));
1030 if (new_mode
== CM_WRITE
&& needs_check
) {
1031 DMERR("%s: unable to switch cache to write mode until repaired.",
1032 cache_device_name(cache
));
1033 if (old_mode
!= new_mode
)
1034 new_mode
= old_mode
;
1036 new_mode
= CM_READ_ONLY
;
1039 /* Never move out of fail mode */
1040 if (old_mode
== CM_FAIL
)
1046 dm_cache_metadata_set_read_only(cache
->cmd
);
1050 dm_cache_metadata_set_read_write(cache
->cmd
);
1054 cache
->features
.mode
= new_mode
;
1056 if (new_mode
!= old_mode
)
1057 notify_mode_switch(cache
, new_mode
);
1060 static void abort_transaction(struct cache
*cache
)
1062 const char *dev_name
= cache_device_name(cache
);
1064 if (get_cache_mode(cache
) >= CM_READ_ONLY
)
1067 if (dm_cache_metadata_set_needs_check(cache
->cmd
)) {
1068 DMERR("%s: failed to set 'needs_check' flag in metadata", dev_name
);
1069 set_cache_mode(cache
, CM_FAIL
);
1072 DMERR_LIMIT("%s: aborting current metadata transaction", dev_name
);
1073 if (dm_cache_metadata_abort(cache
->cmd
)) {
1074 DMERR("%s: failed to abort metadata transaction", dev_name
);
1075 set_cache_mode(cache
, CM_FAIL
);
1079 static void metadata_operation_failed(struct cache
*cache
, const char *op
, int r
)
1081 DMERR_LIMIT("%s: metadata operation '%s' failed: error = %d",
1082 cache_device_name(cache
), op
, r
);
1083 abort_transaction(cache
);
1084 set_cache_mode(cache
, CM_READ_ONLY
);
1087 /*----------------------------------------------------------------*/
1089 static void load_stats(struct cache
*cache
)
1091 struct dm_cache_statistics stats
;
1093 dm_cache_metadata_get_stats(cache
->cmd
, &stats
);
1094 atomic_set(&cache
->stats
.read_hit
, stats
.read_hits
);
1095 atomic_set(&cache
->stats
.read_miss
, stats
.read_misses
);
1096 atomic_set(&cache
->stats
.write_hit
, stats
.write_hits
);
1097 atomic_set(&cache
->stats
.write_miss
, stats
.write_misses
);
1100 static void save_stats(struct cache
*cache
)
1102 struct dm_cache_statistics stats
;
1104 if (get_cache_mode(cache
) >= CM_READ_ONLY
)
1107 stats
.read_hits
= atomic_read(&cache
->stats
.read_hit
);
1108 stats
.read_misses
= atomic_read(&cache
->stats
.read_miss
);
1109 stats
.write_hits
= atomic_read(&cache
->stats
.write_hit
);
1110 stats
.write_misses
= atomic_read(&cache
->stats
.write_miss
);
1112 dm_cache_metadata_set_stats(cache
->cmd
, &stats
);
1115 static void update_stats(struct cache_stats
*stats
, enum policy_operation op
)
1118 case POLICY_PROMOTE
:
1119 atomic_inc(&stats
->promotion
);
1123 atomic_inc(&stats
->demotion
);
1126 case POLICY_WRITEBACK
:
1127 atomic_inc(&stats
->writeback
);
1132 /*----------------------------------------------------------------
1133 * Migration processing
1135 * Migration covers moving data from the origin device to the cache, or
1137 *--------------------------------------------------------------*/
1139 static void inc_io_migrations(struct cache
*cache
)
1141 atomic_inc(&cache
->nr_io_migrations
);
1144 static void dec_io_migrations(struct cache
*cache
)
1146 atomic_dec(&cache
->nr_io_migrations
);
1149 static bool discard_or_flush(struct bio
*bio
)
1151 return bio_op(bio
) == REQ_OP_DISCARD
|| op_is_flush(bio
->bi_opf
);
1154 static void calc_discard_block_range(struct cache
*cache
, struct bio
*bio
,
1155 dm_dblock_t
*b
, dm_dblock_t
*e
)
1157 sector_t sb
= bio
->bi_iter
.bi_sector
;
1158 sector_t se
= bio_end_sector(bio
);
1160 *b
= to_dblock(dm_sector_div_up(sb
, cache
->discard_block_size
));
1162 if (se
- sb
< cache
->discard_block_size
)
1165 *e
= to_dblock(block_div(se
, cache
->discard_block_size
));
1168 /*----------------------------------------------------------------*/
1170 static void prevent_background_work(struct cache
*cache
)
1173 down_write(&cache
->background_work_lock
);
1177 static void allow_background_work(struct cache
*cache
)
1180 up_write(&cache
->background_work_lock
);
1184 static bool background_work_begin(struct cache
*cache
)
1189 r
= down_read_trylock(&cache
->background_work_lock
);
1195 static void background_work_end(struct cache
*cache
)
1198 up_read(&cache
->background_work_lock
);
1202 /*----------------------------------------------------------------*/
1204 static void quiesce(struct dm_cache_migration
*mg
,
1205 void (*continuation
)(struct work_struct
*))
1207 init_continuation(&mg
->k
, continuation
);
1208 dm_cell_quiesce_v2(mg
->cache
->prison
, mg
->cell
, &mg
->k
.ws
);
1211 static struct dm_cache_migration
*ws_to_mg(struct work_struct
*ws
)
1213 struct continuation
*k
= container_of(ws
, struct continuation
, ws
);
1214 return container_of(k
, struct dm_cache_migration
, k
);
1217 static void copy_complete(int read_err
, unsigned long write_err
, void *context
)
1219 struct dm_cache_migration
*mg
= container_of(context
, struct dm_cache_migration
, k
);
1221 if (read_err
|| write_err
)
1222 mg
->k
.input
= BLK_STS_IOERR
;
1224 queue_continuation(mg
->cache
->wq
, &mg
->k
);
1227 static int copy(struct dm_cache_migration
*mg
, bool promote
)
1230 struct dm_io_region o_region
, c_region
;
1231 struct cache
*cache
= mg
->cache
;
1233 o_region
.bdev
= cache
->origin_dev
->bdev
;
1234 o_region
.sector
= from_oblock(mg
->op
->oblock
) * cache
->sectors_per_block
;
1235 o_region
.count
= cache
->sectors_per_block
;
1237 c_region
.bdev
= cache
->cache_dev
->bdev
;
1238 c_region
.sector
= from_cblock(mg
->op
->cblock
) * cache
->sectors_per_block
;
1239 c_region
.count
= cache
->sectors_per_block
;
1242 r
= dm_kcopyd_copy(cache
->copier
, &o_region
, 1, &c_region
, 0, copy_complete
, &mg
->k
);
1244 r
= dm_kcopyd_copy(cache
->copier
, &c_region
, 1, &o_region
, 0, copy_complete
, &mg
->k
);
1249 static void bio_drop_shared_lock(struct cache
*cache
, struct bio
*bio
)
1251 size_t pb_data_size
= get_per_bio_data_size(cache
);
1252 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
1254 if (pb
->cell
&& dm_cell_put_v2(cache
->prison
, pb
->cell
))
1255 free_prison_cell(cache
, pb
->cell
);
1259 static void overwrite_endio(struct bio
*bio
)
1261 struct dm_cache_migration
*mg
= bio
->bi_private
;
1262 struct cache
*cache
= mg
->cache
;
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 dm_unhook_bio(&pb
->hook_info
, bio
);
1269 mg
->k
.input
= bio
->bi_status
;
1271 queue_continuation(mg
->cache
->wq
, &mg
->k
);
1274 static void overwrite(struct dm_cache_migration
*mg
,
1275 void (*continuation
)(struct work_struct
*))
1277 struct bio
*bio
= mg
->overwrite_bio
;
1278 size_t pb_data_size
= get_per_bio_data_size(mg
->cache
);
1279 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
1281 dm_hook_bio(&pb
->hook_info
, bio
, overwrite_endio
, mg
);
1284 * The overwrite bio is part of the copy operation, as such it does
1285 * not set/clear discard or dirty flags.
1287 if (mg
->op
->op
== POLICY_PROMOTE
)
1288 remap_to_cache(mg
->cache
, bio
, mg
->op
->cblock
);
1290 remap_to_origin(mg
->cache
, bio
);
1292 init_continuation(&mg
->k
, continuation
);
1293 accounted_request(mg
->cache
, bio
);
1299 * 1) exclusive lock preventing WRITEs
1301 * 3) copy or issue overwrite bio
1302 * 4) upgrade to exclusive lock preventing READs and WRITEs
1304 * 6) update metadata and commit
1307 static void mg_complete(struct dm_cache_migration
*mg
, bool success
)
1309 struct bio_list bios
;
1310 struct cache
*cache
= mg
->cache
;
1311 struct policy_work
*op
= mg
->op
;
1312 dm_cblock_t cblock
= op
->cblock
;
1315 update_stats(&cache
->stats
, op
->op
);
1318 case POLICY_PROMOTE
:
1319 clear_discard(cache
, oblock_to_dblock(cache
, op
->oblock
));
1320 policy_complete_background_work(cache
->policy
, op
, success
);
1322 if (mg
->overwrite_bio
) {
1324 force_set_dirty(cache
, cblock
);
1325 else if (mg
->k
.input
)
1326 mg
->overwrite_bio
->bi_status
= mg
->k
.input
;
1328 mg
->overwrite_bio
->bi_status
= BLK_STS_IOERR
;
1329 bio_endio(mg
->overwrite_bio
);
1332 force_clear_dirty(cache
, cblock
);
1333 dec_io_migrations(cache
);
1339 * We clear dirty here to update the nr_dirty counter.
1342 force_clear_dirty(cache
, cblock
);
1343 policy_complete_background_work(cache
->policy
, op
, success
);
1344 dec_io_migrations(cache
);
1347 case POLICY_WRITEBACK
:
1349 force_clear_dirty(cache
, cblock
);
1350 policy_complete_background_work(cache
->policy
, op
, success
);
1351 dec_io_migrations(cache
);
1355 bio_list_init(&bios
);
1357 if (dm_cell_unlock_v2(cache
->prison
, mg
->cell
, &bios
))
1358 free_prison_cell(cache
, mg
->cell
);
1362 defer_bios(cache
, &bios
);
1363 wake_migration_worker(cache
);
1365 background_work_end(cache
);
1368 static void mg_success(struct work_struct
*ws
)
1370 struct dm_cache_migration
*mg
= ws_to_mg(ws
);
1371 mg_complete(mg
, mg
->k
.input
== 0);
1374 static void mg_update_metadata(struct work_struct
*ws
)
1377 struct dm_cache_migration
*mg
= ws_to_mg(ws
);
1378 struct cache
*cache
= mg
->cache
;
1379 struct policy_work
*op
= mg
->op
;
1382 case POLICY_PROMOTE
:
1383 r
= dm_cache_insert_mapping(cache
->cmd
, op
->cblock
, op
->oblock
);
1385 DMERR_LIMIT("%s: migration failed; couldn't insert mapping",
1386 cache_device_name(cache
));
1387 metadata_operation_failed(cache
, "dm_cache_insert_mapping", r
);
1389 mg_complete(mg
, false);
1392 mg_complete(mg
, true);
1396 r
= dm_cache_remove_mapping(cache
->cmd
, op
->cblock
);
1398 DMERR_LIMIT("%s: migration failed; couldn't update on disk metadata",
1399 cache_device_name(cache
));
1400 metadata_operation_failed(cache
, "dm_cache_remove_mapping", r
);
1402 mg_complete(mg
, false);
1407 * It would be nice if we only had to commit when a REQ_FLUSH
1408 * comes through. But there's one scenario that we have to
1411 * - vblock x in a cache block
1413 * - cache block gets reallocated and over written
1416 * When we recover, because there was no commit the cache will
1417 * rollback to having the data for vblock x in the cache block.
1418 * But the cache block has since been overwritten, so it'll end
1419 * up pointing to data that was never in 'x' during the history
1422 * To avoid this issue we require a commit as part of the
1423 * demotion operation.
1425 init_continuation(&mg
->k
, mg_success
);
1426 continue_after_commit(&cache
->committer
, &mg
->k
);
1427 schedule_commit(&cache
->committer
);
1430 case POLICY_WRITEBACK
:
1431 mg_complete(mg
, true);
1436 static void mg_update_metadata_after_copy(struct work_struct
*ws
)
1438 struct dm_cache_migration
*mg
= ws_to_mg(ws
);
1441 * Did the copy succeed?
1444 mg_complete(mg
, false);
1446 mg_update_metadata(ws
);
1449 static void mg_upgrade_lock(struct work_struct
*ws
)
1452 struct dm_cache_migration
*mg
= ws_to_mg(ws
);
1455 * Did the copy succeed?
1458 mg_complete(mg
, false);
1462 * Now we want the lock to prevent both reads and writes.
1464 r
= dm_cell_lock_promote_v2(mg
->cache
->prison
, mg
->cell
,
1465 READ_WRITE_LOCK_LEVEL
);
1467 mg_complete(mg
, false);
1470 quiesce(mg
, mg_update_metadata
);
1473 mg_update_metadata(ws
);
1477 static void mg_copy(struct work_struct
*ws
)
1480 struct dm_cache_migration
*mg
= ws_to_mg(ws
);
1482 if (mg
->overwrite_bio
) {
1484 * It's safe to do this here, even though it's new data
1485 * because all IO has been locked out of the block.
1487 * mg_lock_writes() already took READ_WRITE_LOCK_LEVEL
1488 * so _not_ using mg_upgrade_lock() as continutation.
1490 overwrite(mg
, mg_update_metadata_after_copy
);
1493 struct cache
*cache
= mg
->cache
;
1494 struct policy_work
*op
= mg
->op
;
1495 bool is_policy_promote
= (op
->op
== POLICY_PROMOTE
);
1497 if ((!is_policy_promote
&& !is_dirty(cache
, op
->cblock
)) ||
1498 is_discarded_oblock(cache
, op
->oblock
)) {
1499 mg_upgrade_lock(ws
);
1503 init_continuation(&mg
->k
, mg_upgrade_lock
);
1505 r
= copy(mg
, is_policy_promote
);
1507 DMERR_LIMIT("%s: migration copy failed", cache_device_name(cache
));
1508 mg
->k
.input
= BLK_STS_IOERR
;
1509 mg_complete(mg
, false);
1514 static int mg_lock_writes(struct dm_cache_migration
*mg
)
1517 struct dm_cell_key_v2 key
;
1518 struct cache
*cache
= mg
->cache
;
1519 struct dm_bio_prison_cell_v2
*prealloc
;
1521 prealloc
= alloc_prison_cell(cache
);
1523 DMERR_LIMIT("%s: alloc_prison_cell failed", cache_device_name(cache
));
1524 mg_complete(mg
, false);
1529 * Prevent writes to the block, but allow reads to continue.
1530 * Unless we're using an overwrite bio, in which case we lock
1533 build_key(mg
->op
->oblock
, oblock_succ(mg
->op
->oblock
), &key
);
1534 r
= dm_cell_lock_v2(cache
->prison
, &key
,
1535 mg
->overwrite_bio
? READ_WRITE_LOCK_LEVEL
: WRITE_LOCK_LEVEL
,
1536 prealloc
, &mg
->cell
);
1538 free_prison_cell(cache
, prealloc
);
1539 mg_complete(mg
, false);
1543 if (mg
->cell
!= prealloc
)
1544 free_prison_cell(cache
, prealloc
);
1549 quiesce(mg
, mg_copy
);
1554 static int mg_start(struct cache
*cache
, struct policy_work
*op
, struct bio
*bio
)
1556 struct dm_cache_migration
*mg
;
1558 if (!background_work_begin(cache
)) {
1559 policy_complete_background_work(cache
->policy
, op
, false);
1563 mg
= alloc_migration(cache
);
1565 policy_complete_background_work(cache
->policy
, op
, false);
1566 background_work_end(cache
);
1570 memset(mg
, 0, sizeof(*mg
));
1574 mg
->overwrite_bio
= bio
;
1577 inc_io_migrations(cache
);
1579 return mg_lock_writes(mg
);
1582 /*----------------------------------------------------------------
1583 * invalidation processing
1584 *--------------------------------------------------------------*/
1586 static void invalidate_complete(struct dm_cache_migration
*mg
, bool success
)
1588 struct bio_list bios
;
1589 struct cache
*cache
= mg
->cache
;
1591 bio_list_init(&bios
);
1592 if (dm_cell_unlock_v2(cache
->prison
, mg
->cell
, &bios
))
1593 free_prison_cell(cache
, mg
->cell
);
1595 if (!success
&& mg
->overwrite_bio
)
1596 bio_io_error(mg
->overwrite_bio
);
1599 defer_bios(cache
, &bios
);
1601 background_work_end(cache
);
1604 static void invalidate_completed(struct work_struct
*ws
)
1606 struct dm_cache_migration
*mg
= ws_to_mg(ws
);
1607 invalidate_complete(mg
, !mg
->k
.input
);
1610 static int invalidate_cblock(struct cache
*cache
, dm_cblock_t cblock
)
1612 int r
= policy_invalidate_mapping(cache
->policy
, cblock
);
1614 r
= dm_cache_remove_mapping(cache
->cmd
, cblock
);
1616 DMERR_LIMIT("%s: invalidation failed; couldn't update on disk metadata",
1617 cache_device_name(cache
));
1618 metadata_operation_failed(cache
, "dm_cache_remove_mapping", r
);
1621 } else if (r
== -ENODATA
) {
1623 * Harmless, already unmapped.
1628 DMERR("%s: policy_invalidate_mapping failed", cache_device_name(cache
));
1633 static void invalidate_remove(struct work_struct
*ws
)
1636 struct dm_cache_migration
*mg
= ws_to_mg(ws
);
1637 struct cache
*cache
= mg
->cache
;
1639 r
= invalidate_cblock(cache
, mg
->invalidate_cblock
);
1641 invalidate_complete(mg
, false);
1645 init_continuation(&mg
->k
, invalidate_completed
);
1646 continue_after_commit(&cache
->committer
, &mg
->k
);
1647 remap_to_origin_clear_discard(cache
, mg
->overwrite_bio
, mg
->invalidate_oblock
);
1648 mg
->overwrite_bio
= NULL
;
1649 schedule_commit(&cache
->committer
);
1652 static int invalidate_lock(struct dm_cache_migration
*mg
)
1655 struct dm_cell_key_v2 key
;
1656 struct cache
*cache
= mg
->cache
;
1657 struct dm_bio_prison_cell_v2
*prealloc
;
1659 prealloc
= alloc_prison_cell(cache
);
1661 invalidate_complete(mg
, false);
1665 build_key(mg
->invalidate_oblock
, oblock_succ(mg
->invalidate_oblock
), &key
);
1666 r
= dm_cell_lock_v2(cache
->prison
, &key
,
1667 READ_WRITE_LOCK_LEVEL
, prealloc
, &mg
->cell
);
1669 free_prison_cell(cache
, prealloc
);
1670 invalidate_complete(mg
, false);
1674 if (mg
->cell
!= prealloc
)
1675 free_prison_cell(cache
, prealloc
);
1678 quiesce(mg
, invalidate_remove
);
1682 * We can't call invalidate_remove() directly here because we
1683 * might still be in request context.
1685 init_continuation(&mg
->k
, invalidate_remove
);
1686 queue_work(cache
->wq
, &mg
->k
.ws
);
1692 static int invalidate_start(struct cache
*cache
, dm_cblock_t cblock
,
1693 dm_oblock_t oblock
, struct bio
*bio
)
1695 struct dm_cache_migration
*mg
;
1697 if (!background_work_begin(cache
))
1700 mg
= alloc_migration(cache
);
1702 background_work_end(cache
);
1706 memset(mg
, 0, sizeof(*mg
));
1709 mg
->overwrite_bio
= bio
;
1710 mg
->invalidate_cblock
= cblock
;
1711 mg
->invalidate_oblock
= oblock
;
1713 return invalidate_lock(mg
);
1716 /*----------------------------------------------------------------
1718 *--------------------------------------------------------------*/
1725 static enum busy
spare_migration_bandwidth(struct cache
*cache
)
1727 bool idle
= iot_idle_for(&cache
->tracker
, HZ
);
1728 sector_t current_volume
= (atomic_read(&cache
->nr_io_migrations
) + 1) *
1729 cache
->sectors_per_block
;
1731 if (idle
&& current_volume
<= cache
->migration_threshold
)
1737 static void inc_hit_counter(struct cache
*cache
, struct bio
*bio
)
1739 atomic_inc(bio_data_dir(bio
) == READ
?
1740 &cache
->stats
.read_hit
: &cache
->stats
.write_hit
);
1743 static void inc_miss_counter(struct cache
*cache
, struct bio
*bio
)
1745 atomic_inc(bio_data_dir(bio
) == READ
?
1746 &cache
->stats
.read_miss
: &cache
->stats
.write_miss
);
1749 /*----------------------------------------------------------------*/
1751 static bool bio_writes_complete_block(struct cache
*cache
, struct bio
*bio
)
1753 return (bio_data_dir(bio
) == WRITE
) &&
1754 (bio
->bi_iter
.bi_size
== (cache
->sectors_per_block
<< SECTOR_SHIFT
));
1757 static bool optimisable_bio(struct cache
*cache
, struct bio
*bio
, dm_oblock_t block
)
1759 return writeback_mode(&cache
->features
) &&
1760 (is_discarded_oblock(cache
, block
) || bio_writes_complete_block(cache
, bio
));
1763 static int map_bio(struct cache
*cache
, struct bio
*bio
, dm_oblock_t block
,
1764 bool *commit_needed
)
1767 bool rb
, background_queued
;
1769 size_t pb_data_size
= get_per_bio_data_size(cache
);
1770 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
1772 *commit_needed
= false;
1774 rb
= bio_detain_shared(cache
, block
, bio
);
1777 * An exclusive lock is held for this block, so we have to
1778 * wait. We set the commit_needed flag so the current
1779 * transaction will be committed asap, allowing this lock
1782 *commit_needed
= true;
1783 return DM_MAPIO_SUBMITTED
;
1786 data_dir
= bio_data_dir(bio
);
1788 if (optimisable_bio(cache
, bio
, block
)) {
1789 struct policy_work
*op
= NULL
;
1791 r
= policy_lookup_with_work(cache
->policy
, block
, &cblock
, data_dir
, true, &op
);
1792 if (unlikely(r
&& r
!= -ENOENT
)) {
1793 DMERR_LIMIT("%s: policy_lookup_with_work() failed with r = %d",
1794 cache_device_name(cache
), r
);
1796 return DM_MAPIO_SUBMITTED
;
1799 if (r
== -ENOENT
&& op
) {
1800 bio_drop_shared_lock(cache
, bio
);
1801 BUG_ON(op
->op
!= POLICY_PROMOTE
);
1802 mg_start(cache
, op
, bio
);
1803 return DM_MAPIO_SUBMITTED
;
1806 r
= policy_lookup(cache
->policy
, block
, &cblock
, data_dir
, false, &background_queued
);
1807 if (unlikely(r
&& r
!= -ENOENT
)) {
1808 DMERR_LIMIT("%s: policy_lookup() failed with r = %d",
1809 cache_device_name(cache
), r
);
1811 return DM_MAPIO_SUBMITTED
;
1814 if (background_queued
)
1815 wake_migration_worker(cache
);
1822 inc_miss_counter(cache
, bio
);
1823 if (pb
->req_nr
== 0) {
1824 accounted_begin(cache
, bio
);
1825 remap_to_origin_clear_discard(cache
, bio
, block
);
1829 * This is a duplicate writethrough io that is no
1830 * longer needed because the block has been demoted.
1833 return DM_MAPIO_SUBMITTED
;
1839 inc_hit_counter(cache
, bio
);
1842 * Passthrough always maps to the origin, invalidating any
1843 * cache blocks that are written to.
1845 if (passthrough_mode(&cache
->features
)) {
1846 if (bio_data_dir(bio
) == WRITE
) {
1847 bio_drop_shared_lock(cache
, bio
);
1848 atomic_inc(&cache
->stats
.demotion
);
1849 invalidate_start(cache
, cblock
, block
, bio
);
1851 remap_to_origin_clear_discard(cache
, bio
, block
);
1854 if (bio_data_dir(bio
) == WRITE
&& writethrough_mode(&cache
->features
) &&
1855 !is_dirty(cache
, cblock
)) {
1856 remap_to_origin_then_cache(cache
, bio
, block
, cblock
);
1857 accounted_begin(cache
, bio
);
1859 remap_to_cache_dirty(cache
, bio
, block
, cblock
);
1864 * dm core turns FUA requests into a separate payload and FLUSH req.
1866 if (bio
->bi_opf
& REQ_FUA
) {
1868 * issue_after_commit will call accounted_begin a second time. So
1869 * we call accounted_complete() to avoid double accounting.
1871 accounted_complete(cache
, bio
);
1872 issue_after_commit(&cache
->committer
, bio
);
1873 *commit_needed
= true;
1874 return DM_MAPIO_SUBMITTED
;
1877 return DM_MAPIO_REMAPPED
;
1880 static bool process_bio(struct cache
*cache
, struct bio
*bio
)
1884 if (map_bio(cache
, bio
, get_bio_block(cache
, bio
), &commit_needed
) == DM_MAPIO_REMAPPED
)
1885 generic_make_request(bio
);
1887 return commit_needed
;
1891 * A non-zero return indicates read_only or fail_io mode.
1893 static int commit(struct cache
*cache
, bool clean_shutdown
)
1897 if (get_cache_mode(cache
) >= CM_READ_ONLY
)
1900 atomic_inc(&cache
->stats
.commit_count
);
1901 r
= dm_cache_commit(cache
->cmd
, clean_shutdown
);
1903 metadata_operation_failed(cache
, "dm_cache_commit", r
);
1909 * Used by the batcher.
1911 static blk_status_t
commit_op(void *context
)
1913 struct cache
*cache
= context
;
1915 if (dm_cache_changed_this_transaction(cache
->cmd
))
1916 return errno_to_blk_status(commit(cache
, false));
1921 /*----------------------------------------------------------------*/
1923 static bool process_flush_bio(struct cache
*cache
, struct bio
*bio
)
1925 size_t pb_data_size
= get_per_bio_data_size(cache
);
1926 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
1929 remap_to_origin(cache
, bio
);
1931 remap_to_cache(cache
, bio
, 0);
1933 issue_after_commit(&cache
->committer
, bio
);
1937 static bool process_discard_bio(struct cache
*cache
, struct bio
*bio
)
1941 // FIXME: do we need to lock the region? Or can we just assume the
1942 // user wont be so foolish as to issue discard concurrently with
1944 calc_discard_block_range(cache
, bio
, &b
, &e
);
1946 set_discard(cache
, b
);
1947 b
= to_dblock(from_dblock(b
) + 1);
1955 static void process_deferred_bios(struct work_struct
*ws
)
1957 struct cache
*cache
= container_of(ws
, struct cache
, deferred_bio_worker
);
1959 unsigned long flags
;
1960 bool commit_needed
= false;
1961 struct bio_list bios
;
1964 bio_list_init(&bios
);
1966 spin_lock_irqsave(&cache
->lock
, flags
);
1967 bio_list_merge(&bios
, &cache
->deferred_bios
);
1968 bio_list_init(&cache
->deferred_bios
);
1969 spin_unlock_irqrestore(&cache
->lock
, flags
);
1971 while ((bio
= bio_list_pop(&bios
))) {
1972 if (bio
->bi_opf
& REQ_PREFLUSH
)
1973 commit_needed
= process_flush_bio(cache
, bio
) || commit_needed
;
1975 else if (bio_op(bio
) == REQ_OP_DISCARD
)
1976 commit_needed
= process_discard_bio(cache
, bio
) || commit_needed
;
1979 commit_needed
= process_bio(cache
, bio
) || commit_needed
;
1983 schedule_commit(&cache
->committer
);
1986 static void process_deferred_writethrough_bios(struct work_struct
*ws
)
1988 struct cache
*cache
= container_of(ws
, struct cache
, deferred_writethrough_worker
);
1990 unsigned long flags
;
1991 struct bio_list bios
;
1994 bio_list_init(&bios
);
1996 spin_lock_irqsave(&cache
->lock
, flags
);
1997 bio_list_merge(&bios
, &cache
->deferred_writethrough_bios
);
1998 bio_list_init(&cache
->deferred_writethrough_bios
);
1999 spin_unlock_irqrestore(&cache
->lock
, flags
);
2002 * These bios have already been through accounted_begin()
2004 while ((bio
= bio_list_pop(&bios
)))
2005 generic_make_request(bio
);
2008 /*----------------------------------------------------------------
2010 *--------------------------------------------------------------*/
2012 static void requeue_deferred_bios(struct cache
*cache
)
2015 struct bio_list bios
;
2017 bio_list_init(&bios
);
2018 bio_list_merge(&bios
, &cache
->deferred_bios
);
2019 bio_list_init(&cache
->deferred_bios
);
2021 while ((bio
= bio_list_pop(&bios
))) {
2022 bio
->bi_status
= BLK_STS_DM_REQUEUE
;
2028 * We want to commit periodically so that not too much
2029 * unwritten metadata builds up.
2031 static void do_waker(struct work_struct
*ws
)
2033 struct cache
*cache
= container_of(to_delayed_work(ws
), struct cache
, waker
);
2035 policy_tick(cache
->policy
, true);
2036 wake_migration_worker(cache
);
2037 schedule_commit(&cache
->committer
);
2038 queue_delayed_work(cache
->wq
, &cache
->waker
, COMMIT_PERIOD
);
2041 static void check_migrations(struct work_struct
*ws
)
2044 struct policy_work
*op
;
2045 struct cache
*cache
= container_of(ws
, struct cache
, migration_worker
);
2049 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
->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
,
2825 blk_status_t
*error
)
2827 struct cache
*cache
= ti
->private;
2828 unsigned long flags
;
2829 size_t pb_data_size
= get_per_bio_data_size(cache
);
2830 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
2833 policy_tick(cache
->policy
, false);
2835 spin_lock_irqsave(&cache
->lock
, flags
);
2836 cache
->need_tick_bio
= true;
2837 spin_unlock_irqrestore(&cache
->lock
, flags
);
2840 bio_drop_shared_lock(cache
, bio
);
2841 accounted_complete(cache
, bio
);
2843 return DM_ENDIO_DONE
;
2846 static int write_dirty_bitset(struct cache
*cache
)
2850 if (get_cache_mode(cache
) >= CM_READ_ONLY
)
2853 r
= dm_cache_set_dirty_bits(cache
->cmd
, from_cblock(cache
->cache_size
), cache
->dirty_bitset
);
2855 metadata_operation_failed(cache
, "dm_cache_set_dirty_bits", r
);
2860 static int write_discard_bitset(struct cache
*cache
)
2864 if (get_cache_mode(cache
) >= CM_READ_ONLY
)
2867 r
= dm_cache_discard_bitset_resize(cache
->cmd
, cache
->discard_block_size
,
2868 cache
->discard_nr_blocks
);
2870 DMERR("%s: could not resize on-disk discard bitset", cache_device_name(cache
));
2871 metadata_operation_failed(cache
, "dm_cache_discard_bitset_resize", r
);
2875 for (i
= 0; i
< from_dblock(cache
->discard_nr_blocks
); i
++) {
2876 r
= dm_cache_set_discard(cache
->cmd
, to_dblock(i
),
2877 is_discarded(cache
, to_dblock(i
)));
2879 metadata_operation_failed(cache
, "dm_cache_set_discard", r
);
2887 static int write_hints(struct cache
*cache
)
2891 if (get_cache_mode(cache
) >= CM_READ_ONLY
)
2894 r
= dm_cache_write_hints(cache
->cmd
, cache
->policy
);
2896 metadata_operation_failed(cache
, "dm_cache_write_hints", r
);
2904 * returns true on success
2906 static bool sync_metadata(struct cache
*cache
)
2910 r1
= write_dirty_bitset(cache
);
2912 DMERR("%s: could not write dirty bitset", cache_device_name(cache
));
2914 r2
= write_discard_bitset(cache
);
2916 DMERR("%s: could not write discard bitset", cache_device_name(cache
));
2920 r3
= write_hints(cache
);
2922 DMERR("%s: could not write hints", cache_device_name(cache
));
2925 * If writing the above metadata failed, we still commit, but don't
2926 * set the clean shutdown flag. This will effectively force every
2927 * dirty bit to be set on reload.
2929 r4
= commit(cache
, !r1
&& !r2
&& !r3
);
2931 DMERR("%s: could not write cache metadata", cache_device_name(cache
));
2933 return !r1
&& !r2
&& !r3
&& !r4
;
2936 static void cache_postsuspend(struct dm_target
*ti
)
2938 struct cache
*cache
= ti
->private;
2940 prevent_background_work(cache
);
2941 BUG_ON(atomic_read(&cache
->nr_io_migrations
));
2943 cancel_delayed_work(&cache
->waker
);
2944 flush_workqueue(cache
->wq
);
2945 WARN_ON(cache
->tracker
.in_flight
);
2948 * If it's a flush suspend there won't be any deferred bios, so this
2951 requeue_deferred_bios(cache
);
2953 if (get_cache_mode(cache
) == CM_WRITE
)
2954 (void) sync_metadata(cache
);
2957 static int load_mapping(void *context
, dm_oblock_t oblock
, dm_cblock_t cblock
,
2958 bool dirty
, uint32_t hint
, bool hint_valid
)
2961 struct cache
*cache
= context
;
2964 set_bit(from_cblock(cblock
), cache
->dirty_bitset
);
2965 atomic_inc(&cache
->nr_dirty
);
2967 clear_bit(from_cblock(cblock
), cache
->dirty_bitset
);
2969 r
= policy_load_mapping(cache
->policy
, oblock
, cblock
, dirty
, hint
, hint_valid
);
2977 * The discard block size in the on disk metadata is not
2978 * neccessarily the same as we're currently using. So we have to
2979 * be careful to only set the discarded attribute if we know it
2980 * covers a complete block of the new size.
2982 struct discard_load_info
{
2983 struct cache
*cache
;
2986 * These blocks are sized using the on disk dblock size, rather
2987 * than the current one.
2989 dm_block_t block_size
;
2990 dm_block_t discard_begin
, discard_end
;
2993 static void discard_load_info_init(struct cache
*cache
,
2994 struct discard_load_info
*li
)
2997 li
->discard_begin
= li
->discard_end
= 0;
3000 static void set_discard_range(struct discard_load_info
*li
)
3004 if (li
->discard_begin
== li
->discard_end
)
3008 * Convert to sectors.
3010 b
= li
->discard_begin
* li
->block_size
;
3011 e
= li
->discard_end
* li
->block_size
;
3014 * Then convert back to the current dblock size.
3016 b
= dm_sector_div_up(b
, li
->cache
->discard_block_size
);
3017 sector_div(e
, li
->cache
->discard_block_size
);
3020 * The origin may have shrunk, so we need to check we're still in
3023 if (e
> from_dblock(li
->cache
->discard_nr_blocks
))
3024 e
= from_dblock(li
->cache
->discard_nr_blocks
);
3027 set_discard(li
->cache
, to_dblock(b
));
3030 static int load_discard(void *context
, sector_t discard_block_size
,
3031 dm_dblock_t dblock
, bool discard
)
3033 struct discard_load_info
*li
= context
;
3035 li
->block_size
= discard_block_size
;
3038 if (from_dblock(dblock
) == li
->discard_end
)
3040 * We're already in a discard range, just extend it.
3042 li
->discard_end
= li
->discard_end
+ 1ULL;
3046 * Emit the old range and start a new one.
3048 set_discard_range(li
);
3049 li
->discard_begin
= from_dblock(dblock
);
3050 li
->discard_end
= li
->discard_begin
+ 1ULL;
3053 set_discard_range(li
);
3054 li
->discard_begin
= li
->discard_end
= 0;
3060 static dm_cblock_t
get_cache_dev_size(struct cache
*cache
)
3062 sector_t size
= get_dev_size(cache
->cache_dev
);
3063 (void) sector_div(size
, cache
->sectors_per_block
);
3064 return to_cblock(size
);
3067 static bool can_resize(struct cache
*cache
, dm_cblock_t new_size
)
3069 if (from_cblock(new_size
) > from_cblock(cache
->cache_size
))
3073 * We can't drop a dirty block when shrinking the cache.
3075 while (from_cblock(new_size
) < from_cblock(cache
->cache_size
)) {
3076 new_size
= to_cblock(from_cblock(new_size
) + 1);
3077 if (is_dirty(cache
, new_size
)) {
3078 DMERR("%s: unable to shrink cache; cache block %llu is dirty",
3079 cache_device_name(cache
),
3080 (unsigned long long) from_cblock(new_size
));
3088 static int resize_cache_dev(struct cache
*cache
, dm_cblock_t new_size
)
3092 r
= dm_cache_resize(cache
->cmd
, new_size
);
3094 DMERR("%s: could not resize cache metadata", cache_device_name(cache
));
3095 metadata_operation_failed(cache
, "dm_cache_resize", r
);
3099 set_cache_size(cache
, new_size
);
3104 static int cache_preresume(struct dm_target
*ti
)
3107 struct cache
*cache
= ti
->private;
3108 dm_cblock_t csize
= get_cache_dev_size(cache
);
3111 * Check to see if the cache has resized.
3113 if (!cache
->sized
) {
3114 r
= resize_cache_dev(cache
, csize
);
3118 cache
->sized
= true;
3120 } else if (csize
!= cache
->cache_size
) {
3121 if (!can_resize(cache
, csize
))
3124 r
= resize_cache_dev(cache
, csize
);
3129 if (!cache
->loaded_mappings
) {
3130 r
= dm_cache_load_mappings(cache
->cmd
, cache
->policy
,
3131 load_mapping
, cache
);
3133 DMERR("%s: could not load cache mappings", cache_device_name(cache
));
3134 metadata_operation_failed(cache
, "dm_cache_load_mappings", r
);
3138 cache
->loaded_mappings
= true;
3141 if (!cache
->loaded_discards
) {
3142 struct discard_load_info li
;
3145 * The discard bitset could have been resized, or the
3146 * discard block size changed. To be safe we start by
3147 * setting every dblock to not discarded.
3149 clear_bitset(cache
->discard_bitset
, from_dblock(cache
->discard_nr_blocks
));
3151 discard_load_info_init(cache
, &li
);
3152 r
= dm_cache_load_discards(cache
->cmd
, load_discard
, &li
);
3154 DMERR("%s: could not load origin discards", cache_device_name(cache
));
3155 metadata_operation_failed(cache
, "dm_cache_load_discards", r
);
3158 set_discard_range(&li
);
3160 cache
->loaded_discards
= true;
3166 static void cache_resume(struct dm_target
*ti
)
3168 struct cache
*cache
= ti
->private;
3170 cache
->need_tick_bio
= true;
3171 allow_background_work(cache
);
3172 do_waker(&cache
->waker
.work
);
3178 * <metadata block size> <#used metadata blocks>/<#total metadata blocks>
3179 * <cache block size> <#used cache blocks>/<#total cache blocks>
3180 * <#read hits> <#read misses> <#write hits> <#write misses>
3181 * <#demotions> <#promotions> <#dirty>
3182 * <#features> <features>*
3183 * <#core args> <core args>
3184 * <policy name> <#policy args> <policy args>* <cache metadata mode> <needs_check>
3186 static void cache_status(struct dm_target
*ti
, status_type_t type
,
3187 unsigned status_flags
, char *result
, unsigned maxlen
)
3192 dm_block_t nr_free_blocks_metadata
= 0;
3193 dm_block_t nr_blocks_metadata
= 0;
3194 char buf
[BDEVNAME_SIZE
];
3195 struct cache
*cache
= ti
->private;
3196 dm_cblock_t residency
;
3200 case STATUSTYPE_INFO
:
3201 if (get_cache_mode(cache
) == CM_FAIL
) {
3206 /* Commit to ensure statistics aren't out-of-date */
3207 if (!(status_flags
& DM_STATUS_NOFLUSH_FLAG
) && !dm_suspended(ti
))
3208 (void) commit(cache
, false);
3210 r
= dm_cache_get_free_metadata_block_count(cache
->cmd
, &nr_free_blocks_metadata
);
3212 DMERR("%s: dm_cache_get_free_metadata_block_count returned %d",
3213 cache_device_name(cache
), r
);
3217 r
= dm_cache_get_metadata_dev_size(cache
->cmd
, &nr_blocks_metadata
);
3219 DMERR("%s: dm_cache_get_metadata_dev_size returned %d",
3220 cache_device_name(cache
), r
);
3224 residency
= policy_residency(cache
->policy
);
3226 DMEMIT("%u %llu/%llu %llu %llu/%llu %u %u %u %u %u %u %lu ",
3227 (unsigned)DM_CACHE_METADATA_BLOCK_SIZE
,
3228 (unsigned long long)(nr_blocks_metadata
- nr_free_blocks_metadata
),
3229 (unsigned long long)nr_blocks_metadata
,
3230 (unsigned long long)cache
->sectors_per_block
,
3231 (unsigned long long) from_cblock(residency
),
3232 (unsigned long long) from_cblock(cache
->cache_size
),
3233 (unsigned) atomic_read(&cache
->stats
.read_hit
),
3234 (unsigned) atomic_read(&cache
->stats
.read_miss
),
3235 (unsigned) atomic_read(&cache
->stats
.write_hit
),
3236 (unsigned) atomic_read(&cache
->stats
.write_miss
),
3237 (unsigned) atomic_read(&cache
->stats
.demotion
),
3238 (unsigned) atomic_read(&cache
->stats
.promotion
),
3239 (unsigned long) atomic_read(&cache
->nr_dirty
));
3241 if (cache
->features
.metadata_version
== 2)
3242 DMEMIT("2 metadata2 ");
3246 if (writethrough_mode(&cache
->features
))
3247 DMEMIT("writethrough ");
3249 else if (passthrough_mode(&cache
->features
))
3250 DMEMIT("passthrough ");
3252 else if (writeback_mode(&cache
->features
))
3253 DMEMIT("writeback ");
3256 DMERR("%s: internal error: unknown io mode: %d",
3257 cache_device_name(cache
), (int) cache
->features
.io_mode
);
3261 DMEMIT("2 migration_threshold %llu ", (unsigned long long) cache
->migration_threshold
);
3263 DMEMIT("%s ", dm_cache_policy_get_name(cache
->policy
));
3265 r
= policy_emit_config_values(cache
->policy
, result
, maxlen
, &sz
);
3267 DMERR("%s: policy_emit_config_values returned %d",
3268 cache_device_name(cache
), r
);
3271 if (get_cache_mode(cache
) == CM_READ_ONLY
)
3276 r
= dm_cache_metadata_needs_check(cache
->cmd
, &needs_check
);
3278 if (r
|| needs_check
)
3279 DMEMIT("needs_check ");
3285 case STATUSTYPE_TABLE
:
3286 format_dev_t(buf
, cache
->metadata_dev
->bdev
->bd_dev
);
3288 format_dev_t(buf
, cache
->cache_dev
->bdev
->bd_dev
);
3290 format_dev_t(buf
, cache
->origin_dev
->bdev
->bd_dev
);
3293 for (i
= 0; i
< cache
->nr_ctr_args
- 1; i
++)
3294 DMEMIT(" %s", cache
->ctr_args
[i
]);
3295 if (cache
->nr_ctr_args
)
3296 DMEMIT(" %s", cache
->ctr_args
[cache
->nr_ctr_args
- 1]);
3306 * Defines a range of cblocks, begin to (end - 1) are in the range. end is
3307 * the one-past-the-end value.
3309 struct cblock_range
{
3315 * A cache block range can take two forms:
3317 * i) A single cblock, eg. '3456'
3318 * ii) A begin and end cblock with a dash between, eg. 123-234
3320 static int parse_cblock_range(struct cache
*cache
, const char *str
,
3321 struct cblock_range
*result
)
3328 * Try and parse form (ii) first.
3330 r
= sscanf(str
, "%llu-%llu%c", &b
, &e
, &dummy
);
3335 result
->begin
= to_cblock(b
);
3336 result
->end
= to_cblock(e
);
3341 * That didn't work, try form (i).
3343 r
= sscanf(str
, "%llu%c", &b
, &dummy
);
3348 result
->begin
= to_cblock(b
);
3349 result
->end
= to_cblock(from_cblock(result
->begin
) + 1u);
3353 DMERR("%s: invalid cblock range '%s'", cache_device_name(cache
), str
);
3357 static int validate_cblock_range(struct cache
*cache
, struct cblock_range
*range
)
3359 uint64_t b
= from_cblock(range
->begin
);
3360 uint64_t e
= from_cblock(range
->end
);
3361 uint64_t n
= from_cblock(cache
->cache_size
);
3364 DMERR("%s: begin cblock out of range: %llu >= %llu",
3365 cache_device_name(cache
), b
, n
);
3370 DMERR("%s: end cblock out of range: %llu > %llu",
3371 cache_device_name(cache
), e
, n
);
3376 DMERR("%s: invalid cblock range: %llu >= %llu",
3377 cache_device_name(cache
), b
, e
);
3384 static inline dm_cblock_t
cblock_succ(dm_cblock_t b
)
3386 return to_cblock(from_cblock(b
) + 1);
3389 static int request_invalidation(struct cache
*cache
, struct cblock_range
*range
)
3394 * We don't need to do any locking here because we know we're in
3395 * passthrough mode. There's is potential for a race between an
3396 * invalidation triggered by an io and an invalidation message. This
3397 * is harmless, we must not worry if the policy call fails.
3399 while (range
->begin
!= range
->end
) {
3400 r
= invalidate_cblock(cache
, range
->begin
);
3404 range
->begin
= cblock_succ(range
->begin
);
3407 cache
->commit_requested
= true;
3411 static int process_invalidate_cblocks_message(struct cache
*cache
, unsigned count
,
3412 const char **cblock_ranges
)
3416 struct cblock_range range
;
3418 if (!passthrough_mode(&cache
->features
)) {
3419 DMERR("%s: cache has to be in passthrough mode for invalidation",
3420 cache_device_name(cache
));
3424 for (i
= 0; i
< count
; i
++) {
3425 r
= parse_cblock_range(cache
, cblock_ranges
[i
], &range
);
3429 r
= validate_cblock_range(cache
, &range
);
3434 * Pass begin and end origin blocks to the worker and wake it.
3436 r
= request_invalidation(cache
, &range
);
3448 * "invalidate_cblocks [(<begin>)|(<begin>-<end>)]*
3450 * The key migration_threshold is supported by the cache target core.
3452 static int cache_message(struct dm_target
*ti
, unsigned argc
, char **argv
)
3454 struct cache
*cache
= ti
->private;
3459 if (get_cache_mode(cache
) >= CM_READ_ONLY
) {
3460 DMERR("%s: unable to service cache target messages in READ_ONLY or FAIL mode",
3461 cache_device_name(cache
));
3465 if (!strcasecmp(argv
[0], "invalidate_cblocks"))
3466 return process_invalidate_cblocks_message(cache
, argc
- 1, (const char **) argv
+ 1);
3471 return set_config_value(cache
, argv
[0], argv
[1]);
3474 static int cache_iterate_devices(struct dm_target
*ti
,
3475 iterate_devices_callout_fn fn
, void *data
)
3478 struct cache
*cache
= ti
->private;
3480 r
= fn(ti
, cache
->cache_dev
, 0, get_dev_size(cache
->cache_dev
), data
);
3482 r
= fn(ti
, cache
->origin_dev
, 0, ti
->len
, data
);
3487 static void set_discard_limits(struct cache
*cache
, struct queue_limits
*limits
)
3490 * FIXME: these limits may be incompatible with the cache device
3492 limits
->max_discard_sectors
= min_t(sector_t
, cache
->discard_block_size
* 1024,
3493 cache
->origin_sectors
);
3494 limits
->discard_granularity
= cache
->discard_block_size
<< SECTOR_SHIFT
;
3497 static void cache_io_hints(struct dm_target
*ti
, struct queue_limits
*limits
)
3499 struct cache
*cache
= ti
->private;
3500 uint64_t io_opt_sectors
= limits
->io_opt
>> SECTOR_SHIFT
;
3503 * If the system-determined stacked limits are compatible with the
3504 * cache's blocksize (io_opt is a factor) do not override them.
3506 if (io_opt_sectors
< cache
->sectors_per_block
||
3507 do_div(io_opt_sectors
, cache
->sectors_per_block
)) {
3508 blk_limits_io_min(limits
, cache
->sectors_per_block
<< SECTOR_SHIFT
);
3509 blk_limits_io_opt(limits
, cache
->sectors_per_block
<< SECTOR_SHIFT
);
3511 set_discard_limits(cache
, limits
);
3514 /*----------------------------------------------------------------*/
3516 static struct target_type cache_target
= {
3518 .version
= {2, 0, 0},
3519 .module
= THIS_MODULE
,
3523 .end_io
= cache_end_io
,
3524 .postsuspend
= cache_postsuspend
,
3525 .preresume
= cache_preresume
,
3526 .resume
= cache_resume
,
3527 .status
= cache_status
,
3528 .message
= cache_message
,
3529 .iterate_devices
= cache_iterate_devices
,
3530 .io_hints
= cache_io_hints
,
3533 static int __init
dm_cache_init(void)
3537 r
= dm_register_target(&cache_target
);
3539 DMERR("cache target registration failed: %d", r
);
3543 migration_cache
= KMEM_CACHE(dm_cache_migration
, 0);
3544 if (!migration_cache
) {
3545 dm_unregister_target(&cache_target
);
3552 static void __exit
dm_cache_exit(void)
3554 dm_unregister_target(&cache_target
);
3555 kmem_cache_destroy(migration_cache
);
3558 module_init(dm_cache_init
);
3559 module_exit(dm_cache_exit
);
3561 MODULE_DESCRIPTION(DM_NAME
" cache target");
3562 MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
3563 MODULE_LICENSE("GPL");