2 * Copyright (C) 2012 Red Hat. All rights reserved.
4 * This file is released under the GPL.
8 #include "dm-bio-prison.h"
9 #include "dm-bio-record.h"
10 #include "dm-cache-metadata.h"
12 #include <linux/dm-io.h>
13 #include <linux/dm-kcopyd.h>
14 #include <linux/init.h>
15 #include <linux/mempool.h>
16 #include <linux/module.h>
17 #include <linux/slab.h>
18 #include <linux/vmalloc.h>
20 #define DM_MSG_PREFIX "cache"
22 DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(cache_copy_throttle
,
23 "A percentage of time allocated for copying to and/or from cache");
25 /*----------------------------------------------------------------*/
30 * oblock: index of an origin block
31 * cblock: index of a cache block
32 * promotion: movement of a block from origin to cache
33 * demotion: movement of a block from cache to origin
34 * migration: movement of a block between the origin and cache device,
38 /*----------------------------------------------------------------*/
40 static size_t bitset_size_in_bytes(unsigned nr_entries
)
42 return sizeof(unsigned long) * dm_div_up(nr_entries
, BITS_PER_LONG
);
45 static unsigned long *alloc_bitset(unsigned nr_entries
)
47 size_t s
= bitset_size_in_bytes(nr_entries
);
51 static void clear_bitset(void *bitset
, unsigned nr_entries
)
53 size_t s
= bitset_size_in_bytes(nr_entries
);
57 static void free_bitset(unsigned long *bits
)
62 /*----------------------------------------------------------------*/
64 #define PRISON_CELLS 1024
65 #define MIGRATION_POOL_SIZE 128
66 #define COMMIT_PERIOD HZ
67 #define MIGRATION_COUNT_WINDOW 10
70 * The block size of the device holding cache data must be >= 32KB
72 #define DATA_DEV_BLOCK_SIZE_MIN_SECTORS (32 * 1024 >> SECTOR_SHIFT)
75 * FIXME: the cache is read/write for the time being.
78 CM_WRITE
, /* metadata may be changed */
79 CM_READ_ONLY
, /* metadata may not be changed */
82 struct cache_features
{
94 atomic_t copies_avoided
;
95 atomic_t cache_cell_clash
;
96 atomic_t commit_count
;
97 atomic_t discard_count
;
101 struct dm_target
*ti
;
102 struct dm_target_callbacks callbacks
;
105 * Metadata is written to this device.
107 struct dm_dev
*metadata_dev
;
110 * The slower of the two data devices. Typically a spindle.
112 struct dm_dev
*origin_dev
;
115 * The faster of the two data devices. Typically an SSD.
117 struct dm_dev
*cache_dev
;
120 * Cache features such as write-through.
122 struct cache_features features
;
125 * Size of the origin device in _complete_ blocks and native sectors.
127 dm_oblock_t origin_blocks
;
128 sector_t origin_sectors
;
131 * Size of the cache device in blocks.
133 dm_cblock_t cache_size
;
136 * Fields for converting from sectors to blocks.
138 uint32_t sectors_per_block
;
139 int sectors_per_block_shift
;
141 struct dm_cache_metadata
*cmd
;
144 struct bio_list deferred_bios
;
145 struct bio_list deferred_flush_bios
;
146 struct bio_list deferred_writethrough_bios
;
147 struct list_head quiesced_migrations
;
148 struct list_head completed_migrations
;
149 struct list_head need_commit_migrations
;
150 sector_t migration_threshold
;
151 atomic_t nr_migrations
;
152 wait_queue_head_t migration_wait
;
155 * cache_size entries, dirty if set
157 dm_cblock_t nr_dirty
;
158 unsigned long *dirty_bitset
;
161 * origin_blocks entries, discarded if set.
163 uint32_t discard_block_size
; /* a power of 2 times sectors per block */
164 dm_dblock_t discard_nr_blocks
;
165 unsigned long *discard_bitset
;
167 struct dm_kcopyd_client
*copier
;
168 struct workqueue_struct
*wq
;
169 struct work_struct worker
;
171 struct delayed_work waker
;
172 unsigned long last_commit_jiffies
;
174 struct dm_bio_prison
*prison
;
175 struct dm_deferred_set
*all_io_ds
;
177 mempool_t
*migration_pool
;
178 struct dm_cache_migration
*next_migration
;
180 struct dm_cache_policy
*policy
;
181 unsigned policy_nr_args
;
183 bool need_tick_bio
:1;
186 bool commit_requested
:1;
187 bool loaded_mappings
:1;
188 bool loaded_discards
:1;
190 struct cache_stats stats
;
193 * Rather than reconstructing the table line for the status we just
194 * save it and regurgitate.
196 unsigned nr_ctr_args
;
197 const char **ctr_args
;
200 struct per_bio_data
{
203 struct dm_deferred_entry
*all_io_entry
;
206 * writethrough fields. These MUST remain at the end of this
207 * structure and the 'cache' member must be the first as it
208 * is used to determine the offsetof the writethrough fields.
212 bio_end_io_t
*saved_bi_end_io
;
213 struct dm_bio_details bio_details
;
216 struct dm_cache_migration
{
217 struct list_head list
;
220 unsigned long start_jiffies
;
221 dm_oblock_t old_oblock
;
222 dm_oblock_t new_oblock
;
230 struct dm_bio_prison_cell
*old_ocell
;
231 struct dm_bio_prison_cell
*new_ocell
;
235 * Processing a bio in the worker thread may require these memory
236 * allocations. We prealloc to avoid deadlocks (the same worker thread
237 * frees them back to the mempool).
240 struct dm_cache_migration
*mg
;
241 struct dm_bio_prison_cell
*cell1
;
242 struct dm_bio_prison_cell
*cell2
;
245 static void wake_worker(struct cache
*cache
)
247 queue_work(cache
->wq
, &cache
->worker
);
250 /*----------------------------------------------------------------*/
252 static struct dm_bio_prison_cell
*alloc_prison_cell(struct cache
*cache
)
254 /* FIXME: change to use a local slab. */
255 return dm_bio_prison_alloc_cell(cache
->prison
, GFP_NOWAIT
);
258 static void free_prison_cell(struct cache
*cache
, struct dm_bio_prison_cell
*cell
)
260 dm_bio_prison_free_cell(cache
->prison
, cell
);
263 static int prealloc_data_structs(struct cache
*cache
, struct prealloc
*p
)
266 p
->mg
= mempool_alloc(cache
->migration_pool
, GFP_NOWAIT
);
272 p
->cell1
= alloc_prison_cell(cache
);
278 p
->cell2
= alloc_prison_cell(cache
);
286 static void prealloc_free_structs(struct cache
*cache
, struct prealloc
*p
)
289 free_prison_cell(cache
, p
->cell2
);
292 free_prison_cell(cache
, p
->cell1
);
295 mempool_free(p
->mg
, cache
->migration_pool
);
298 static struct dm_cache_migration
*prealloc_get_migration(struct prealloc
*p
)
300 struct dm_cache_migration
*mg
= p
->mg
;
309 * You must have a cell within the prealloc struct to return. If not this
310 * function will BUG() rather than returning NULL.
312 static struct dm_bio_prison_cell
*prealloc_get_cell(struct prealloc
*p
)
314 struct dm_bio_prison_cell
*r
= NULL
;
320 } else if (p
->cell2
) {
330 * You can't have more than two cells in a prealloc struct. BUG() will be
331 * called if you try and overfill.
333 static void prealloc_put_cell(struct prealloc
*p
, struct dm_bio_prison_cell
*cell
)
345 /*----------------------------------------------------------------*/
347 static void build_key(dm_oblock_t oblock
, struct dm_cell_key
*key
)
351 key
->block
= from_oblock(oblock
);
355 * The caller hands in a preallocated cell, and a free function for it.
356 * The cell will be freed if there's an error, or if it wasn't used because
357 * a cell with that key already exists.
359 typedef void (*cell_free_fn
)(void *context
, struct dm_bio_prison_cell
*cell
);
361 static int bio_detain(struct cache
*cache
, dm_oblock_t oblock
,
362 struct bio
*bio
, struct dm_bio_prison_cell
*cell_prealloc
,
363 cell_free_fn free_fn
, void *free_context
,
364 struct dm_bio_prison_cell
**cell_result
)
367 struct dm_cell_key key
;
369 build_key(oblock
, &key
);
370 r
= dm_bio_detain(cache
->prison
, &key
, bio
, cell_prealloc
, cell_result
);
372 free_fn(free_context
, cell_prealloc
);
377 static int get_cell(struct cache
*cache
,
379 struct prealloc
*structs
,
380 struct dm_bio_prison_cell
**cell_result
)
383 struct dm_cell_key key
;
384 struct dm_bio_prison_cell
*cell_prealloc
;
386 cell_prealloc
= prealloc_get_cell(structs
);
388 build_key(oblock
, &key
);
389 r
= dm_get_cell(cache
->prison
, &key
, cell_prealloc
, cell_result
);
391 prealloc_put_cell(structs
, cell_prealloc
);
396 /*----------------------------------------------------------------*/
398 static bool is_dirty(struct cache
*cache
, dm_cblock_t b
)
400 return test_bit(from_cblock(b
), cache
->dirty_bitset
);
403 static void set_dirty(struct cache
*cache
, dm_oblock_t oblock
, dm_cblock_t cblock
)
405 if (!test_and_set_bit(from_cblock(cblock
), cache
->dirty_bitset
)) {
406 cache
->nr_dirty
= to_cblock(from_cblock(cache
->nr_dirty
) + 1);
407 policy_set_dirty(cache
->policy
, oblock
);
411 static void clear_dirty(struct cache
*cache
, dm_oblock_t oblock
, dm_cblock_t cblock
)
413 if (test_and_clear_bit(from_cblock(cblock
), cache
->dirty_bitset
)) {
414 policy_clear_dirty(cache
->policy
, oblock
);
415 cache
->nr_dirty
= to_cblock(from_cblock(cache
->nr_dirty
) - 1);
416 if (!from_cblock(cache
->nr_dirty
))
417 dm_table_event(cache
->ti
->table
);
421 /*----------------------------------------------------------------*/
422 static bool block_size_is_power_of_two(struct cache
*cache
)
424 return cache
->sectors_per_block_shift
>= 0;
427 static dm_block_t
block_div(dm_block_t b
, uint32_t n
)
434 static dm_dblock_t
oblock_to_dblock(struct cache
*cache
, dm_oblock_t oblock
)
436 uint32_t discard_blocks
= cache
->discard_block_size
;
437 dm_block_t b
= from_oblock(oblock
);
439 if (!block_size_is_power_of_two(cache
))
440 discard_blocks
= discard_blocks
/ cache
->sectors_per_block
;
442 discard_blocks
>>= cache
->sectors_per_block_shift
;
444 b
= block_div(b
, discard_blocks
);
449 static void set_discard(struct cache
*cache
, dm_dblock_t b
)
453 atomic_inc(&cache
->stats
.discard_count
);
455 spin_lock_irqsave(&cache
->lock
, flags
);
456 set_bit(from_dblock(b
), cache
->discard_bitset
);
457 spin_unlock_irqrestore(&cache
->lock
, flags
);
460 static void clear_discard(struct cache
*cache
, dm_dblock_t b
)
464 spin_lock_irqsave(&cache
->lock
, flags
);
465 clear_bit(from_dblock(b
), cache
->discard_bitset
);
466 spin_unlock_irqrestore(&cache
->lock
, flags
);
469 static bool is_discarded(struct cache
*cache
, dm_dblock_t b
)
474 spin_lock_irqsave(&cache
->lock
, flags
);
475 r
= test_bit(from_dblock(b
), cache
->discard_bitset
);
476 spin_unlock_irqrestore(&cache
->lock
, flags
);
481 static bool is_discarded_oblock(struct cache
*cache
, dm_oblock_t b
)
486 spin_lock_irqsave(&cache
->lock
, flags
);
487 r
= test_bit(from_dblock(oblock_to_dblock(cache
, b
)),
488 cache
->discard_bitset
);
489 spin_unlock_irqrestore(&cache
->lock
, flags
);
494 /*----------------------------------------------------------------*/
496 static void load_stats(struct cache
*cache
)
498 struct dm_cache_statistics stats
;
500 dm_cache_metadata_get_stats(cache
->cmd
, &stats
);
501 atomic_set(&cache
->stats
.read_hit
, stats
.read_hits
);
502 atomic_set(&cache
->stats
.read_miss
, stats
.read_misses
);
503 atomic_set(&cache
->stats
.write_hit
, stats
.write_hits
);
504 atomic_set(&cache
->stats
.write_miss
, stats
.write_misses
);
507 static void save_stats(struct cache
*cache
)
509 struct dm_cache_statistics stats
;
511 stats
.read_hits
= atomic_read(&cache
->stats
.read_hit
);
512 stats
.read_misses
= atomic_read(&cache
->stats
.read_miss
);
513 stats
.write_hits
= atomic_read(&cache
->stats
.write_hit
);
514 stats
.write_misses
= atomic_read(&cache
->stats
.write_miss
);
516 dm_cache_metadata_set_stats(cache
->cmd
, &stats
);
519 /*----------------------------------------------------------------
521 *--------------------------------------------------------------*/
524 * If using writeback, leave out struct per_bio_data's writethrough fields.
526 #define PB_DATA_SIZE_WB (offsetof(struct per_bio_data, cache))
527 #define PB_DATA_SIZE_WT (sizeof(struct per_bio_data))
529 static size_t get_per_bio_data_size(struct cache
*cache
)
531 return cache
->features
.write_through
? PB_DATA_SIZE_WT
: PB_DATA_SIZE_WB
;
534 static struct per_bio_data
*get_per_bio_data(struct bio
*bio
, size_t data_size
)
536 struct per_bio_data
*pb
= dm_per_bio_data(bio
, data_size
);
541 static struct per_bio_data
*init_per_bio_data(struct bio
*bio
, size_t data_size
)
543 struct per_bio_data
*pb
= get_per_bio_data(bio
, data_size
);
546 pb
->req_nr
= dm_bio_get_target_bio_nr(bio
);
547 pb
->all_io_entry
= NULL
;
552 /*----------------------------------------------------------------
554 *--------------------------------------------------------------*/
555 static void remap_to_origin(struct cache
*cache
, struct bio
*bio
)
557 bio
->bi_bdev
= cache
->origin_dev
->bdev
;
560 static void remap_to_cache(struct cache
*cache
, struct bio
*bio
,
563 sector_t bi_sector
= bio
->bi_sector
;
565 bio
->bi_bdev
= cache
->cache_dev
->bdev
;
566 if (!block_size_is_power_of_two(cache
))
567 bio
->bi_sector
= (from_cblock(cblock
) * cache
->sectors_per_block
) +
568 sector_div(bi_sector
, cache
->sectors_per_block
);
570 bio
->bi_sector
= (from_cblock(cblock
) << cache
->sectors_per_block_shift
) |
571 (bi_sector
& (cache
->sectors_per_block
- 1));
574 static void check_if_tick_bio_needed(struct cache
*cache
, struct bio
*bio
)
577 size_t pb_data_size
= get_per_bio_data_size(cache
);
578 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
580 spin_lock_irqsave(&cache
->lock
, flags
);
581 if (cache
->need_tick_bio
&&
582 !(bio
->bi_rw
& (REQ_FUA
| REQ_FLUSH
| REQ_DISCARD
))) {
584 cache
->need_tick_bio
= false;
586 spin_unlock_irqrestore(&cache
->lock
, flags
);
589 static void remap_to_origin_clear_discard(struct cache
*cache
, struct bio
*bio
,
592 check_if_tick_bio_needed(cache
, bio
);
593 remap_to_origin(cache
, bio
);
594 if (bio_data_dir(bio
) == WRITE
)
595 clear_discard(cache
, oblock_to_dblock(cache
, oblock
));
598 static void remap_to_cache_dirty(struct cache
*cache
, struct bio
*bio
,
599 dm_oblock_t oblock
, dm_cblock_t cblock
)
601 remap_to_cache(cache
, bio
, cblock
);
602 if (bio_data_dir(bio
) == WRITE
) {
603 set_dirty(cache
, oblock
, cblock
);
604 clear_discard(cache
, oblock_to_dblock(cache
, oblock
));
608 static dm_oblock_t
get_bio_block(struct cache
*cache
, struct bio
*bio
)
610 sector_t block_nr
= bio
->bi_sector
;
612 if (!block_size_is_power_of_two(cache
))
613 (void) sector_div(block_nr
, cache
->sectors_per_block
);
615 block_nr
>>= cache
->sectors_per_block_shift
;
617 return to_oblock(block_nr
);
620 static int bio_triggers_commit(struct cache
*cache
, struct bio
*bio
)
622 return bio
->bi_rw
& (REQ_FLUSH
| REQ_FUA
);
625 static void issue(struct cache
*cache
, struct bio
*bio
)
629 if (!bio_triggers_commit(cache
, bio
)) {
630 generic_make_request(bio
);
635 * Batch together any bios that trigger commits and then issue a
636 * single commit for them in do_worker().
638 spin_lock_irqsave(&cache
->lock
, flags
);
639 cache
->commit_requested
= true;
640 bio_list_add(&cache
->deferred_flush_bios
, bio
);
641 spin_unlock_irqrestore(&cache
->lock
, flags
);
644 static void defer_writethrough_bio(struct cache
*cache
, struct bio
*bio
)
648 spin_lock_irqsave(&cache
->lock
, flags
);
649 bio_list_add(&cache
->deferred_writethrough_bios
, bio
);
650 spin_unlock_irqrestore(&cache
->lock
, flags
);
655 static void writethrough_endio(struct bio
*bio
, int err
)
657 struct per_bio_data
*pb
= get_per_bio_data(bio
, PB_DATA_SIZE_WT
);
658 bio
->bi_end_io
= pb
->saved_bi_end_io
;
665 dm_bio_restore(&pb
->bio_details
, bio
);
666 remap_to_cache(pb
->cache
, bio
, pb
->cblock
);
669 * We can't issue this bio directly, since we're in interrupt
670 * context. So it get's put on a bio list for processing by the
673 defer_writethrough_bio(pb
->cache
, bio
);
677 * When running in writethrough mode we need to send writes to clean blocks
678 * to both the cache and origin devices. In future we'd like to clone the
679 * bio and send them in parallel, but for now we're doing them in
680 * series as this is easier.
682 static void remap_to_origin_then_cache(struct cache
*cache
, struct bio
*bio
,
683 dm_oblock_t oblock
, dm_cblock_t cblock
)
685 struct per_bio_data
*pb
= get_per_bio_data(bio
, PB_DATA_SIZE_WT
);
689 pb
->saved_bi_end_io
= bio
->bi_end_io
;
690 dm_bio_record(&pb
->bio_details
, bio
);
691 bio
->bi_end_io
= writethrough_endio
;
693 remap_to_origin_clear_discard(pb
->cache
, bio
, oblock
);
696 /*----------------------------------------------------------------
697 * Migration processing
699 * Migration covers moving data from the origin device to the cache, or
701 *--------------------------------------------------------------*/
702 static void free_migration(struct dm_cache_migration
*mg
)
704 mempool_free(mg
, mg
->cache
->migration_pool
);
707 static void inc_nr_migrations(struct cache
*cache
)
709 atomic_inc(&cache
->nr_migrations
);
712 static void dec_nr_migrations(struct cache
*cache
)
714 atomic_dec(&cache
->nr_migrations
);
717 * Wake the worker in case we're suspending the target.
719 wake_up(&cache
->migration_wait
);
722 static void __cell_defer(struct cache
*cache
, struct dm_bio_prison_cell
*cell
,
725 (holder
? dm_cell_release
: dm_cell_release_no_holder
)
726 (cache
->prison
, cell
, &cache
->deferred_bios
);
727 free_prison_cell(cache
, cell
);
730 static void cell_defer(struct cache
*cache
, struct dm_bio_prison_cell
*cell
,
735 spin_lock_irqsave(&cache
->lock
, flags
);
736 __cell_defer(cache
, cell
, holder
);
737 spin_unlock_irqrestore(&cache
->lock
, flags
);
742 static void cleanup_migration(struct dm_cache_migration
*mg
)
744 dec_nr_migrations(mg
->cache
);
748 static void migration_failure(struct dm_cache_migration
*mg
)
750 struct cache
*cache
= mg
->cache
;
753 DMWARN_LIMIT("writeback failed; couldn't copy block");
754 set_dirty(cache
, mg
->old_oblock
, mg
->cblock
);
755 cell_defer(cache
, mg
->old_ocell
, false);
757 } else if (mg
->demote
) {
758 DMWARN_LIMIT("demotion failed; couldn't copy block");
759 policy_force_mapping(cache
->policy
, mg
->new_oblock
, mg
->old_oblock
);
761 cell_defer(cache
, mg
->old_ocell
, mg
->promote
? 0 : 1);
763 cell_defer(cache
, mg
->new_ocell
, 1);
765 DMWARN_LIMIT("promotion failed; couldn't copy block");
766 policy_remove_mapping(cache
->policy
, mg
->new_oblock
);
767 cell_defer(cache
, mg
->new_ocell
, 1);
770 cleanup_migration(mg
);
773 static void migration_success_pre_commit(struct dm_cache_migration
*mg
)
776 struct cache
*cache
= mg
->cache
;
779 cell_defer(cache
, mg
->old_ocell
, false);
780 clear_dirty(cache
, mg
->old_oblock
, mg
->cblock
);
781 cleanup_migration(mg
);
784 } else if (mg
->demote
) {
785 if (dm_cache_remove_mapping(cache
->cmd
, mg
->cblock
)) {
786 DMWARN_LIMIT("demotion failed; couldn't update on disk metadata");
787 policy_force_mapping(cache
->policy
, mg
->new_oblock
,
790 cell_defer(cache
, mg
->new_ocell
, true);
791 cleanup_migration(mg
);
795 if (dm_cache_insert_mapping(cache
->cmd
, mg
->cblock
, mg
->new_oblock
)) {
796 DMWARN_LIMIT("promotion failed; couldn't update on disk metadata");
797 policy_remove_mapping(cache
->policy
, mg
->new_oblock
);
798 cleanup_migration(mg
);
803 spin_lock_irqsave(&cache
->lock
, flags
);
804 list_add_tail(&mg
->list
, &cache
->need_commit_migrations
);
805 cache
->commit_requested
= true;
806 spin_unlock_irqrestore(&cache
->lock
, flags
);
809 static void migration_success_post_commit(struct dm_cache_migration
*mg
)
812 struct cache
*cache
= mg
->cache
;
815 DMWARN("writeback unexpectedly triggered commit");
818 } else if (mg
->demote
) {
819 cell_defer(cache
, mg
->old_ocell
, mg
->promote
? 0 : 1);
824 spin_lock_irqsave(&cache
->lock
, flags
);
825 list_add_tail(&mg
->list
, &cache
->quiesced_migrations
);
826 spin_unlock_irqrestore(&cache
->lock
, flags
);
829 cleanup_migration(mg
);
832 cell_defer(cache
, mg
->new_ocell
, true);
833 clear_dirty(cache
, mg
->new_oblock
, mg
->cblock
);
834 cleanup_migration(mg
);
838 static void copy_complete(int read_err
, unsigned long write_err
, void *context
)
841 struct dm_cache_migration
*mg
= (struct dm_cache_migration
*) context
;
842 struct cache
*cache
= mg
->cache
;
844 if (read_err
|| write_err
)
847 spin_lock_irqsave(&cache
->lock
, flags
);
848 list_add_tail(&mg
->list
, &cache
->completed_migrations
);
849 spin_unlock_irqrestore(&cache
->lock
, flags
);
854 static void issue_copy_real(struct dm_cache_migration
*mg
)
857 struct dm_io_region o_region
, c_region
;
858 struct cache
*cache
= mg
->cache
;
860 o_region
.bdev
= cache
->origin_dev
->bdev
;
861 o_region
.count
= cache
->sectors_per_block
;
863 c_region
.bdev
= cache
->cache_dev
->bdev
;
864 c_region
.sector
= from_cblock(mg
->cblock
) * cache
->sectors_per_block
;
865 c_region
.count
= cache
->sectors_per_block
;
867 if (mg
->writeback
|| mg
->demote
) {
869 o_region
.sector
= from_oblock(mg
->old_oblock
) * cache
->sectors_per_block
;
870 r
= dm_kcopyd_copy(cache
->copier
, &c_region
, 1, &o_region
, 0, copy_complete
, mg
);
873 o_region
.sector
= from_oblock(mg
->new_oblock
) * cache
->sectors_per_block
;
874 r
= dm_kcopyd_copy(cache
->copier
, &o_region
, 1, &c_region
, 0, copy_complete
, mg
);
878 migration_failure(mg
);
881 static void avoid_copy(struct dm_cache_migration
*mg
)
883 atomic_inc(&mg
->cache
->stats
.copies_avoided
);
884 migration_success_pre_commit(mg
);
887 static void issue_copy(struct dm_cache_migration
*mg
)
890 struct cache
*cache
= mg
->cache
;
892 if (mg
->writeback
|| mg
->demote
)
893 avoid
= !is_dirty(cache
, mg
->cblock
) ||
894 is_discarded_oblock(cache
, mg
->old_oblock
);
896 avoid
= is_discarded_oblock(cache
, mg
->new_oblock
);
898 avoid
? avoid_copy(mg
) : issue_copy_real(mg
);
901 static void complete_migration(struct dm_cache_migration
*mg
)
904 migration_failure(mg
);
906 migration_success_pre_commit(mg
);
909 static void process_migrations(struct cache
*cache
, struct list_head
*head
,
910 void (*fn
)(struct dm_cache_migration
*))
913 struct list_head list
;
914 struct dm_cache_migration
*mg
, *tmp
;
916 INIT_LIST_HEAD(&list
);
917 spin_lock_irqsave(&cache
->lock
, flags
);
918 list_splice_init(head
, &list
);
919 spin_unlock_irqrestore(&cache
->lock
, flags
);
921 list_for_each_entry_safe(mg
, tmp
, &list
, list
)
925 static void __queue_quiesced_migration(struct dm_cache_migration
*mg
)
927 list_add_tail(&mg
->list
, &mg
->cache
->quiesced_migrations
);
930 static void queue_quiesced_migration(struct dm_cache_migration
*mg
)
933 struct cache
*cache
= mg
->cache
;
935 spin_lock_irqsave(&cache
->lock
, flags
);
936 __queue_quiesced_migration(mg
);
937 spin_unlock_irqrestore(&cache
->lock
, flags
);
942 static void queue_quiesced_migrations(struct cache
*cache
, struct list_head
*work
)
945 struct dm_cache_migration
*mg
, *tmp
;
947 spin_lock_irqsave(&cache
->lock
, flags
);
948 list_for_each_entry_safe(mg
, tmp
, work
, list
)
949 __queue_quiesced_migration(mg
);
950 spin_unlock_irqrestore(&cache
->lock
, flags
);
955 static void check_for_quiesced_migrations(struct cache
*cache
,
956 struct per_bio_data
*pb
)
958 struct list_head work
;
960 if (!pb
->all_io_entry
)
963 INIT_LIST_HEAD(&work
);
964 if (pb
->all_io_entry
)
965 dm_deferred_entry_dec(pb
->all_io_entry
, &work
);
967 if (!list_empty(&work
))
968 queue_quiesced_migrations(cache
, &work
);
971 static void quiesce_migration(struct dm_cache_migration
*mg
)
973 if (!dm_deferred_set_add_work(mg
->cache
->all_io_ds
, &mg
->list
))
974 queue_quiesced_migration(mg
);
977 static void promote(struct cache
*cache
, struct prealloc
*structs
,
978 dm_oblock_t oblock
, dm_cblock_t cblock
,
979 struct dm_bio_prison_cell
*cell
)
981 struct dm_cache_migration
*mg
= prealloc_get_migration(structs
);
984 mg
->writeback
= false;
988 mg
->new_oblock
= oblock
;
990 mg
->old_ocell
= NULL
;
991 mg
->new_ocell
= cell
;
992 mg
->start_jiffies
= jiffies
;
994 inc_nr_migrations(cache
);
995 quiesce_migration(mg
);
998 static void writeback(struct cache
*cache
, struct prealloc
*structs
,
999 dm_oblock_t oblock
, dm_cblock_t cblock
,
1000 struct dm_bio_prison_cell
*cell
)
1002 struct dm_cache_migration
*mg
= prealloc_get_migration(structs
);
1005 mg
->writeback
= true;
1007 mg
->promote
= false;
1009 mg
->old_oblock
= oblock
;
1010 mg
->cblock
= cblock
;
1011 mg
->old_ocell
= cell
;
1012 mg
->new_ocell
= NULL
;
1013 mg
->start_jiffies
= jiffies
;
1015 inc_nr_migrations(cache
);
1016 quiesce_migration(mg
);
1019 static void demote_then_promote(struct cache
*cache
, struct prealloc
*structs
,
1020 dm_oblock_t old_oblock
, dm_oblock_t new_oblock
,
1022 struct dm_bio_prison_cell
*old_ocell
,
1023 struct dm_bio_prison_cell
*new_ocell
)
1025 struct dm_cache_migration
*mg
= prealloc_get_migration(structs
);
1028 mg
->writeback
= false;
1032 mg
->old_oblock
= old_oblock
;
1033 mg
->new_oblock
= new_oblock
;
1034 mg
->cblock
= cblock
;
1035 mg
->old_ocell
= old_ocell
;
1036 mg
->new_ocell
= new_ocell
;
1037 mg
->start_jiffies
= jiffies
;
1039 inc_nr_migrations(cache
);
1040 quiesce_migration(mg
);
1043 /*----------------------------------------------------------------
1045 *--------------------------------------------------------------*/
1046 static void defer_bio(struct cache
*cache
, struct bio
*bio
)
1048 unsigned long flags
;
1050 spin_lock_irqsave(&cache
->lock
, flags
);
1051 bio_list_add(&cache
->deferred_bios
, bio
);
1052 spin_unlock_irqrestore(&cache
->lock
, flags
);
1057 static void process_flush_bio(struct cache
*cache
, struct bio
*bio
)
1059 size_t pb_data_size
= get_per_bio_data_size(cache
);
1060 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
1062 BUG_ON(bio
->bi_size
);
1064 remap_to_origin(cache
, bio
);
1066 remap_to_cache(cache
, bio
, 0);
1072 * People generally discard large parts of a device, eg, the whole device
1073 * when formatting. Splitting these large discards up into cache block
1074 * sized ios and then quiescing (always neccessary for discard) takes too
1077 * We keep it simple, and allow any size of discard to come in, and just
1078 * mark off blocks on the discard bitset. No passdown occurs!
1080 * To implement passdown we need to change the bio_prison such that a cell
1081 * can have a key that spans many blocks.
1083 static void process_discard_bio(struct cache
*cache
, struct bio
*bio
)
1085 dm_block_t start_block
= dm_sector_div_up(bio
->bi_sector
,
1086 cache
->discard_block_size
);
1087 dm_block_t end_block
= bio
->bi_sector
+ bio_sectors(bio
);
1090 end_block
= block_div(end_block
, cache
->discard_block_size
);
1092 for (b
= start_block
; b
< end_block
; b
++)
1093 set_discard(cache
, to_dblock(b
));
1098 static bool spare_migration_bandwidth(struct cache
*cache
)
1100 sector_t current_volume
= (atomic_read(&cache
->nr_migrations
) + 1) *
1101 cache
->sectors_per_block
;
1102 return current_volume
< cache
->migration_threshold
;
1105 static bool is_writethrough_io(struct cache
*cache
, struct bio
*bio
,
1108 return bio_data_dir(bio
) == WRITE
&&
1109 cache
->features
.write_through
&& !is_dirty(cache
, cblock
);
1112 static void inc_hit_counter(struct cache
*cache
, struct bio
*bio
)
1114 atomic_inc(bio_data_dir(bio
) == READ
?
1115 &cache
->stats
.read_hit
: &cache
->stats
.write_hit
);
1118 static void inc_miss_counter(struct cache
*cache
, struct bio
*bio
)
1120 atomic_inc(bio_data_dir(bio
) == READ
?
1121 &cache
->stats
.read_miss
: &cache
->stats
.write_miss
);
1124 static void process_bio(struct cache
*cache
, struct prealloc
*structs
,
1128 bool release_cell
= true;
1129 dm_oblock_t block
= get_bio_block(cache
, bio
);
1130 struct dm_bio_prison_cell
*cell_prealloc
, *old_ocell
, *new_ocell
;
1131 struct policy_result lookup_result
;
1132 size_t pb_data_size
= get_per_bio_data_size(cache
);
1133 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
1134 bool discarded_block
= is_discarded_oblock(cache
, block
);
1135 bool can_migrate
= discarded_block
|| spare_migration_bandwidth(cache
);
1138 * Check to see if that block is currently migrating.
1140 cell_prealloc
= prealloc_get_cell(structs
);
1141 r
= bio_detain(cache
, block
, bio
, cell_prealloc
,
1142 (cell_free_fn
) prealloc_put_cell
,
1143 structs
, &new_ocell
);
1147 r
= policy_map(cache
->policy
, block
, true, can_migrate
, discarded_block
,
1148 bio
, &lookup_result
);
1150 if (r
== -EWOULDBLOCK
)
1151 /* migration has been denied */
1152 lookup_result
.op
= POLICY_MISS
;
1154 switch (lookup_result
.op
) {
1156 inc_hit_counter(cache
, bio
);
1157 pb
->all_io_entry
= dm_deferred_entry_inc(cache
->all_io_ds
);
1159 if (is_writethrough_io(cache
, bio
, lookup_result
.cblock
))
1160 remap_to_origin_then_cache(cache
, bio
, block
, lookup_result
.cblock
);
1162 remap_to_cache_dirty(cache
, bio
, block
, lookup_result
.cblock
);
1168 inc_miss_counter(cache
, bio
);
1169 pb
->all_io_entry
= dm_deferred_entry_inc(cache
->all_io_ds
);
1170 remap_to_origin_clear_discard(cache
, bio
, block
);
1175 atomic_inc(&cache
->stats
.promotion
);
1176 promote(cache
, structs
, block
, lookup_result
.cblock
, new_ocell
);
1177 release_cell
= false;
1180 case POLICY_REPLACE
:
1181 cell_prealloc
= prealloc_get_cell(structs
);
1182 r
= bio_detain(cache
, lookup_result
.old_oblock
, bio
, cell_prealloc
,
1183 (cell_free_fn
) prealloc_put_cell
,
1184 structs
, &old_ocell
);
1187 * We have to be careful to avoid lock inversion of
1188 * the cells. So we back off, and wait for the
1189 * old_ocell to become free.
1191 policy_force_mapping(cache
->policy
, block
,
1192 lookup_result
.old_oblock
);
1193 atomic_inc(&cache
->stats
.cache_cell_clash
);
1196 atomic_inc(&cache
->stats
.demotion
);
1197 atomic_inc(&cache
->stats
.promotion
);
1199 demote_then_promote(cache
, structs
, lookup_result
.old_oblock
,
1200 block
, lookup_result
.cblock
,
1201 old_ocell
, new_ocell
);
1202 release_cell
= false;
1206 DMERR_LIMIT("%s: erroring bio, unknown policy op: %u", __func__
,
1207 (unsigned) lookup_result
.op
);
1212 cell_defer(cache
, new_ocell
, false);
1215 static int need_commit_due_to_time(struct cache
*cache
)
1217 return jiffies
< cache
->last_commit_jiffies
||
1218 jiffies
> cache
->last_commit_jiffies
+ COMMIT_PERIOD
;
1221 static int commit_if_needed(struct cache
*cache
)
1223 if (dm_cache_changed_this_transaction(cache
->cmd
) &&
1224 (cache
->commit_requested
|| need_commit_due_to_time(cache
))) {
1225 atomic_inc(&cache
->stats
.commit_count
);
1226 cache
->last_commit_jiffies
= jiffies
;
1227 cache
->commit_requested
= false;
1228 return dm_cache_commit(cache
->cmd
, false);
1234 static void process_deferred_bios(struct cache
*cache
)
1236 unsigned long flags
;
1237 struct bio_list bios
;
1239 struct prealloc structs
;
1241 memset(&structs
, 0, sizeof(structs
));
1242 bio_list_init(&bios
);
1244 spin_lock_irqsave(&cache
->lock
, flags
);
1245 bio_list_merge(&bios
, &cache
->deferred_bios
);
1246 bio_list_init(&cache
->deferred_bios
);
1247 spin_unlock_irqrestore(&cache
->lock
, flags
);
1249 while (!bio_list_empty(&bios
)) {
1251 * If we've got no free migration structs, and processing
1252 * this bio might require one, we pause until there are some
1253 * prepared mappings to process.
1255 if (prealloc_data_structs(cache
, &structs
)) {
1256 spin_lock_irqsave(&cache
->lock
, flags
);
1257 bio_list_merge(&cache
->deferred_bios
, &bios
);
1258 spin_unlock_irqrestore(&cache
->lock
, flags
);
1262 bio
= bio_list_pop(&bios
);
1264 if (bio
->bi_rw
& REQ_FLUSH
)
1265 process_flush_bio(cache
, bio
);
1266 else if (bio
->bi_rw
& REQ_DISCARD
)
1267 process_discard_bio(cache
, bio
);
1269 process_bio(cache
, &structs
, bio
);
1272 prealloc_free_structs(cache
, &structs
);
1275 static void process_deferred_flush_bios(struct cache
*cache
, bool submit_bios
)
1277 unsigned long flags
;
1278 struct bio_list bios
;
1281 bio_list_init(&bios
);
1283 spin_lock_irqsave(&cache
->lock
, flags
);
1284 bio_list_merge(&bios
, &cache
->deferred_flush_bios
);
1285 bio_list_init(&cache
->deferred_flush_bios
);
1286 spin_unlock_irqrestore(&cache
->lock
, flags
);
1288 while ((bio
= bio_list_pop(&bios
)))
1289 submit_bios
? generic_make_request(bio
) : bio_io_error(bio
);
1292 static void process_deferred_writethrough_bios(struct cache
*cache
)
1294 unsigned long flags
;
1295 struct bio_list bios
;
1298 bio_list_init(&bios
);
1300 spin_lock_irqsave(&cache
->lock
, flags
);
1301 bio_list_merge(&bios
, &cache
->deferred_writethrough_bios
);
1302 bio_list_init(&cache
->deferred_writethrough_bios
);
1303 spin_unlock_irqrestore(&cache
->lock
, flags
);
1305 while ((bio
= bio_list_pop(&bios
)))
1306 generic_make_request(bio
);
1309 static void writeback_some_dirty_blocks(struct cache
*cache
)
1314 struct prealloc structs
;
1315 struct dm_bio_prison_cell
*old_ocell
;
1317 memset(&structs
, 0, sizeof(structs
));
1319 while (spare_migration_bandwidth(cache
)) {
1320 if (prealloc_data_structs(cache
, &structs
))
1323 r
= policy_writeback_work(cache
->policy
, &oblock
, &cblock
);
1327 r
= get_cell(cache
, oblock
, &structs
, &old_ocell
);
1329 policy_set_dirty(cache
->policy
, oblock
);
1333 writeback(cache
, &structs
, oblock
, cblock
, old_ocell
);
1336 prealloc_free_structs(cache
, &structs
);
1339 /*----------------------------------------------------------------
1341 *--------------------------------------------------------------*/
1342 static void start_quiescing(struct cache
*cache
)
1344 unsigned long flags
;
1346 spin_lock_irqsave(&cache
->lock
, flags
);
1347 cache
->quiescing
= 1;
1348 spin_unlock_irqrestore(&cache
->lock
, flags
);
1351 static void stop_quiescing(struct cache
*cache
)
1353 unsigned long flags
;
1355 spin_lock_irqsave(&cache
->lock
, flags
);
1356 cache
->quiescing
= 0;
1357 spin_unlock_irqrestore(&cache
->lock
, flags
);
1360 static bool is_quiescing(struct cache
*cache
)
1363 unsigned long flags
;
1365 spin_lock_irqsave(&cache
->lock
, flags
);
1366 r
= cache
->quiescing
;
1367 spin_unlock_irqrestore(&cache
->lock
, flags
);
1372 static void wait_for_migrations(struct cache
*cache
)
1374 wait_event(cache
->migration_wait
, !atomic_read(&cache
->nr_migrations
));
1377 static void stop_worker(struct cache
*cache
)
1379 cancel_delayed_work(&cache
->waker
);
1380 flush_workqueue(cache
->wq
);
1383 static void requeue_deferred_io(struct cache
*cache
)
1386 struct bio_list bios
;
1388 bio_list_init(&bios
);
1389 bio_list_merge(&bios
, &cache
->deferred_bios
);
1390 bio_list_init(&cache
->deferred_bios
);
1392 while ((bio
= bio_list_pop(&bios
)))
1393 bio_endio(bio
, DM_ENDIO_REQUEUE
);
1396 static int more_work(struct cache
*cache
)
1398 if (is_quiescing(cache
))
1399 return !list_empty(&cache
->quiesced_migrations
) ||
1400 !list_empty(&cache
->completed_migrations
) ||
1401 !list_empty(&cache
->need_commit_migrations
);
1403 return !bio_list_empty(&cache
->deferred_bios
) ||
1404 !bio_list_empty(&cache
->deferred_flush_bios
) ||
1405 !bio_list_empty(&cache
->deferred_writethrough_bios
) ||
1406 !list_empty(&cache
->quiesced_migrations
) ||
1407 !list_empty(&cache
->completed_migrations
) ||
1408 !list_empty(&cache
->need_commit_migrations
);
1411 static void do_worker(struct work_struct
*ws
)
1413 struct cache
*cache
= container_of(ws
, struct cache
, worker
);
1416 if (!is_quiescing(cache
))
1417 process_deferred_bios(cache
);
1419 process_migrations(cache
, &cache
->quiesced_migrations
, issue_copy
);
1420 process_migrations(cache
, &cache
->completed_migrations
, complete_migration
);
1422 writeback_some_dirty_blocks(cache
);
1424 process_deferred_writethrough_bios(cache
);
1426 if (commit_if_needed(cache
)) {
1427 process_deferred_flush_bios(cache
, false);
1430 * FIXME: rollback metadata or just go into a
1431 * failure mode and error everything
1434 process_deferred_flush_bios(cache
, true);
1435 process_migrations(cache
, &cache
->need_commit_migrations
,
1436 migration_success_post_commit
);
1438 } while (more_work(cache
));
1442 * We want to commit periodically so that not too much
1443 * unwritten metadata builds up.
1445 static void do_waker(struct work_struct
*ws
)
1447 struct cache
*cache
= container_of(to_delayed_work(ws
), struct cache
, waker
);
1449 queue_delayed_work(cache
->wq
, &cache
->waker
, COMMIT_PERIOD
);
1452 /*----------------------------------------------------------------*/
1454 static int is_congested(struct dm_dev
*dev
, int bdi_bits
)
1456 struct request_queue
*q
= bdev_get_queue(dev
->bdev
);
1457 return bdi_congested(&q
->backing_dev_info
, bdi_bits
);
1460 static int cache_is_congested(struct dm_target_callbacks
*cb
, int bdi_bits
)
1462 struct cache
*cache
= container_of(cb
, struct cache
, callbacks
);
1464 return is_congested(cache
->origin_dev
, bdi_bits
) ||
1465 is_congested(cache
->cache_dev
, bdi_bits
);
1468 /*----------------------------------------------------------------
1470 *--------------------------------------------------------------*/
1473 * This function gets called on the error paths of the constructor, so we
1474 * have to cope with a partially initialised struct.
1476 static void destroy(struct cache
*cache
)
1480 if (cache
->next_migration
)
1481 mempool_free(cache
->next_migration
, cache
->migration_pool
);
1483 if (cache
->migration_pool
)
1484 mempool_destroy(cache
->migration_pool
);
1486 if (cache
->all_io_ds
)
1487 dm_deferred_set_destroy(cache
->all_io_ds
);
1490 dm_bio_prison_destroy(cache
->prison
);
1493 destroy_workqueue(cache
->wq
);
1495 if (cache
->dirty_bitset
)
1496 free_bitset(cache
->dirty_bitset
);
1498 if (cache
->discard_bitset
)
1499 free_bitset(cache
->discard_bitset
);
1502 dm_kcopyd_client_destroy(cache
->copier
);
1505 dm_cache_metadata_close(cache
->cmd
);
1507 if (cache
->metadata_dev
)
1508 dm_put_device(cache
->ti
, cache
->metadata_dev
);
1510 if (cache
->origin_dev
)
1511 dm_put_device(cache
->ti
, cache
->origin_dev
);
1513 if (cache
->cache_dev
)
1514 dm_put_device(cache
->ti
, cache
->cache_dev
);
1517 dm_cache_policy_destroy(cache
->policy
);
1519 for (i
= 0; i
< cache
->nr_ctr_args
; i
++)
1520 kfree(cache
->ctr_args
[i
]);
1521 kfree(cache
->ctr_args
);
1526 static void cache_dtr(struct dm_target
*ti
)
1528 struct cache
*cache
= ti
->private;
1533 static sector_t
get_dev_size(struct dm_dev
*dev
)
1535 return i_size_read(dev
->bdev
->bd_inode
) >> SECTOR_SHIFT
;
1538 /*----------------------------------------------------------------*/
1541 * Construct a cache device mapping.
1543 * cache <metadata dev> <cache dev> <origin dev> <block size>
1544 * <#feature args> [<feature arg>]*
1545 * <policy> <#policy args> [<policy arg>]*
1547 * metadata dev : fast device holding the persistent metadata
1548 * cache dev : fast device holding cached data blocks
1549 * origin dev : slow device holding original data blocks
1550 * block size : cache unit size in sectors
1552 * #feature args : number of feature arguments passed
1553 * feature args : writethrough. (The default is writeback.)
1555 * policy : the replacement policy to use
1556 * #policy args : an even number of policy arguments corresponding
1557 * to key/value pairs passed to the policy
1558 * policy args : key/value pairs passed to the policy
1559 * E.g. 'sequential_threshold 1024'
1560 * See cache-policies.txt for details.
1562 * Optional feature arguments are:
1563 * writethrough : write through caching that prohibits cache block
1564 * content from being different from origin block content.
1565 * Without this argument, the default behaviour is to write
1566 * back cache block contents later for performance reasons,
1567 * so they may differ from the corresponding origin blocks.
1570 struct dm_target
*ti
;
1572 struct dm_dev
*metadata_dev
;
1574 struct dm_dev
*cache_dev
;
1575 sector_t cache_sectors
;
1577 struct dm_dev
*origin_dev
;
1578 sector_t origin_sectors
;
1580 uint32_t block_size
;
1582 const char *policy_name
;
1584 const char **policy_argv
;
1586 struct cache_features features
;
1589 static void destroy_cache_args(struct cache_args
*ca
)
1591 if (ca
->metadata_dev
)
1592 dm_put_device(ca
->ti
, ca
->metadata_dev
);
1595 dm_put_device(ca
->ti
, ca
->cache_dev
);
1598 dm_put_device(ca
->ti
, ca
->origin_dev
);
1603 static bool at_least_one_arg(struct dm_arg_set
*as
, char **error
)
1606 *error
= "Insufficient args";
1613 static int parse_metadata_dev(struct cache_args
*ca
, struct dm_arg_set
*as
,
1617 sector_t metadata_dev_size
;
1618 char b
[BDEVNAME_SIZE
];
1620 if (!at_least_one_arg(as
, error
))
1623 r
= dm_get_device(ca
->ti
, dm_shift_arg(as
), FMODE_READ
| FMODE_WRITE
,
1626 *error
= "Error opening metadata device";
1630 metadata_dev_size
= get_dev_size(ca
->metadata_dev
);
1631 if (metadata_dev_size
> DM_CACHE_METADATA_MAX_SECTORS_WARNING
)
1632 DMWARN("Metadata device %s is larger than %u sectors: excess space will not be used.",
1633 bdevname(ca
->metadata_dev
->bdev
, b
), THIN_METADATA_MAX_SECTORS
);
1638 static int parse_cache_dev(struct cache_args
*ca
, struct dm_arg_set
*as
,
1643 if (!at_least_one_arg(as
, error
))
1646 r
= dm_get_device(ca
->ti
, dm_shift_arg(as
), FMODE_READ
| FMODE_WRITE
,
1649 *error
= "Error opening cache device";
1652 ca
->cache_sectors
= get_dev_size(ca
->cache_dev
);
1657 static int parse_origin_dev(struct cache_args
*ca
, struct dm_arg_set
*as
,
1662 if (!at_least_one_arg(as
, error
))
1665 r
= dm_get_device(ca
->ti
, dm_shift_arg(as
), FMODE_READ
| FMODE_WRITE
,
1668 *error
= "Error opening origin device";
1672 ca
->origin_sectors
= get_dev_size(ca
->origin_dev
);
1673 if (ca
->ti
->len
> ca
->origin_sectors
) {
1674 *error
= "Device size larger than cached device";
1681 static int parse_block_size(struct cache_args
*ca
, struct dm_arg_set
*as
,
1686 if (!at_least_one_arg(as
, error
))
1689 if (kstrtoul(dm_shift_arg(as
), 10, &tmp
) || !tmp
||
1690 tmp
< DATA_DEV_BLOCK_SIZE_MIN_SECTORS
||
1691 tmp
& (DATA_DEV_BLOCK_SIZE_MIN_SECTORS
- 1)) {
1692 *error
= "Invalid data block size";
1696 if (tmp
> ca
->cache_sectors
) {
1697 *error
= "Data block size is larger than the cache device";
1701 ca
->block_size
= tmp
;
1706 static void init_features(struct cache_features
*cf
)
1708 cf
->mode
= CM_WRITE
;
1709 cf
->write_through
= false;
1712 static int parse_features(struct cache_args
*ca
, struct dm_arg_set
*as
,
1715 static struct dm_arg _args
[] = {
1716 {0, 1, "Invalid number of cache feature arguments"},
1722 struct cache_features
*cf
= &ca
->features
;
1726 r
= dm_read_arg_group(_args
, as
, &argc
, error
);
1731 arg
= dm_shift_arg(as
);
1733 if (!strcasecmp(arg
, "writeback"))
1734 cf
->write_through
= false;
1736 else if (!strcasecmp(arg
, "writethrough"))
1737 cf
->write_through
= true;
1740 *error
= "Unrecognised cache feature requested";
1748 static int parse_policy(struct cache_args
*ca
, struct dm_arg_set
*as
,
1751 static struct dm_arg _args
[] = {
1752 {0, 1024, "Invalid number of policy arguments"},
1757 if (!at_least_one_arg(as
, error
))
1760 ca
->policy_name
= dm_shift_arg(as
);
1762 r
= dm_read_arg_group(_args
, as
, &ca
->policy_argc
, error
);
1766 ca
->policy_argv
= (const char **)as
->argv
;
1767 dm_consume_args(as
, ca
->policy_argc
);
1772 static int parse_cache_args(struct cache_args
*ca
, int argc
, char **argv
,
1776 struct dm_arg_set as
;
1781 r
= parse_metadata_dev(ca
, &as
, error
);
1785 r
= parse_cache_dev(ca
, &as
, error
);
1789 r
= parse_origin_dev(ca
, &as
, error
);
1793 r
= parse_block_size(ca
, &as
, error
);
1797 r
= parse_features(ca
, &as
, error
);
1801 r
= parse_policy(ca
, &as
, error
);
1808 /*----------------------------------------------------------------*/
1810 static struct kmem_cache
*migration_cache
;
1812 static int set_config_values(struct dm_cache_policy
*p
, int argc
, const char **argv
)
1817 DMWARN("Odd number of policy arguments given but they should be <key> <value> pairs.");
1822 r
= policy_set_config_value(p
, argv
[0], argv
[1]);
1824 DMWARN("policy_set_config_value failed: key = '%s', value = '%s'",
1836 static int create_cache_policy(struct cache
*cache
, struct cache_args
*ca
,
1841 cache
->policy
= dm_cache_policy_create(ca
->policy_name
,
1843 cache
->origin_sectors
,
1844 cache
->sectors_per_block
);
1845 if (!cache
->policy
) {
1846 *error
= "Error creating cache's policy";
1850 r
= set_config_values(cache
->policy
, ca
->policy_argc
, ca
->policy_argv
);
1852 *error
= "Error setting cache policy's config values";
1853 dm_cache_policy_destroy(cache
->policy
);
1854 cache
->policy
= NULL
;
1861 * We want the discard block size to be a power of two, at least the size
1862 * of the cache block size, and have no more than 2^14 discard blocks
1863 * across the origin.
1865 #define MAX_DISCARD_BLOCKS (1 << 14)
1867 static bool too_many_discard_blocks(sector_t discard_block_size
,
1868 sector_t origin_size
)
1870 (void) sector_div(origin_size
, discard_block_size
);
1872 return origin_size
> MAX_DISCARD_BLOCKS
;
1875 static sector_t
calculate_discard_block_size(sector_t cache_block_size
,
1876 sector_t origin_size
)
1878 sector_t discard_block_size
;
1880 discard_block_size
= roundup_pow_of_two(cache_block_size
);
1883 while (too_many_discard_blocks(discard_block_size
, origin_size
))
1884 discard_block_size
*= 2;
1886 return discard_block_size
;
1889 #define DEFAULT_MIGRATION_THRESHOLD (2048 * 100)
1891 static int cache_create(struct cache_args
*ca
, struct cache
**result
)
1894 char **error
= &ca
->ti
->error
;
1895 struct cache
*cache
;
1896 struct dm_target
*ti
= ca
->ti
;
1897 dm_block_t origin_blocks
;
1898 struct dm_cache_metadata
*cmd
;
1899 bool may_format
= ca
->features
.mode
== CM_WRITE
;
1901 cache
= kzalloc(sizeof(*cache
), GFP_KERNEL
);
1906 ti
->private = cache
;
1907 ti
->num_flush_bios
= 2;
1908 ti
->flush_supported
= true;
1910 ti
->num_discard_bios
= 1;
1911 ti
->discards_supported
= true;
1912 ti
->discard_zeroes_data_unsupported
= true;
1914 memcpy(&cache
->features
, &ca
->features
, sizeof(cache
->features
));
1915 ti
->per_bio_data_size
= get_per_bio_data_size(cache
);
1917 cache
->callbacks
.congested_fn
= cache_is_congested
;
1918 dm_table_add_target_callbacks(ti
->table
, &cache
->callbacks
);
1920 cache
->metadata_dev
= ca
->metadata_dev
;
1921 cache
->origin_dev
= ca
->origin_dev
;
1922 cache
->cache_dev
= ca
->cache_dev
;
1924 ca
->metadata_dev
= ca
->origin_dev
= ca
->cache_dev
= NULL
;
1926 /* FIXME: factor out this whole section */
1927 origin_blocks
= cache
->origin_sectors
= ca
->origin_sectors
;
1928 origin_blocks
= block_div(origin_blocks
, ca
->block_size
);
1929 cache
->origin_blocks
= to_oblock(origin_blocks
);
1931 cache
->sectors_per_block
= ca
->block_size
;
1932 if (dm_set_target_max_io_len(ti
, cache
->sectors_per_block
)) {
1937 if (ca
->block_size
& (ca
->block_size
- 1)) {
1938 dm_block_t cache_size
= ca
->cache_sectors
;
1940 cache
->sectors_per_block_shift
= -1;
1941 cache_size
= block_div(cache_size
, ca
->block_size
);
1942 cache
->cache_size
= to_cblock(cache_size
);
1944 cache
->sectors_per_block_shift
= __ffs(ca
->block_size
);
1945 cache
->cache_size
= to_cblock(ca
->cache_sectors
>> cache
->sectors_per_block_shift
);
1948 r
= create_cache_policy(cache
, ca
, error
);
1951 cache
->policy_nr_args
= ca
->policy_argc
;
1953 cmd
= dm_cache_metadata_open(cache
->metadata_dev
->bdev
,
1954 ca
->block_size
, may_format
,
1955 dm_cache_policy_get_hint_size(cache
->policy
));
1957 *error
= "Error creating metadata object";
1963 spin_lock_init(&cache
->lock
);
1964 bio_list_init(&cache
->deferred_bios
);
1965 bio_list_init(&cache
->deferred_flush_bios
);
1966 bio_list_init(&cache
->deferred_writethrough_bios
);
1967 INIT_LIST_HEAD(&cache
->quiesced_migrations
);
1968 INIT_LIST_HEAD(&cache
->completed_migrations
);
1969 INIT_LIST_HEAD(&cache
->need_commit_migrations
);
1970 cache
->migration_threshold
= DEFAULT_MIGRATION_THRESHOLD
;
1971 atomic_set(&cache
->nr_migrations
, 0);
1972 init_waitqueue_head(&cache
->migration_wait
);
1974 cache
->nr_dirty
= 0;
1975 cache
->dirty_bitset
= alloc_bitset(from_cblock(cache
->cache_size
));
1976 if (!cache
->dirty_bitset
) {
1977 *error
= "could not allocate dirty bitset";
1980 clear_bitset(cache
->dirty_bitset
, from_cblock(cache
->cache_size
));
1982 cache
->discard_block_size
=
1983 calculate_discard_block_size(cache
->sectors_per_block
,
1984 cache
->origin_sectors
);
1985 cache
->discard_nr_blocks
= oblock_to_dblock(cache
, cache
->origin_blocks
);
1986 cache
->discard_bitset
= alloc_bitset(from_dblock(cache
->discard_nr_blocks
));
1987 if (!cache
->discard_bitset
) {
1988 *error
= "could not allocate discard bitset";
1991 clear_bitset(cache
->discard_bitset
, from_dblock(cache
->discard_nr_blocks
));
1993 cache
->copier
= dm_kcopyd_client_create(&dm_kcopyd_throttle
);
1994 if (IS_ERR(cache
->copier
)) {
1995 *error
= "could not create kcopyd client";
1996 r
= PTR_ERR(cache
->copier
);
2000 cache
->wq
= alloc_ordered_workqueue("dm-" DM_MSG_PREFIX
, WQ_MEM_RECLAIM
);
2002 *error
= "could not create workqueue for metadata object";
2005 INIT_WORK(&cache
->worker
, do_worker
);
2006 INIT_DELAYED_WORK(&cache
->waker
, do_waker
);
2007 cache
->last_commit_jiffies
= jiffies
;
2009 cache
->prison
= dm_bio_prison_create(PRISON_CELLS
);
2010 if (!cache
->prison
) {
2011 *error
= "could not create bio prison";
2015 cache
->all_io_ds
= dm_deferred_set_create();
2016 if (!cache
->all_io_ds
) {
2017 *error
= "could not create all_io deferred set";
2021 cache
->migration_pool
= mempool_create_slab_pool(MIGRATION_POOL_SIZE
,
2023 if (!cache
->migration_pool
) {
2024 *error
= "Error creating cache's migration mempool";
2028 cache
->next_migration
= NULL
;
2030 cache
->need_tick_bio
= true;
2031 cache
->sized
= false;
2032 cache
->quiescing
= false;
2033 cache
->commit_requested
= false;
2034 cache
->loaded_mappings
= false;
2035 cache
->loaded_discards
= false;
2039 atomic_set(&cache
->stats
.demotion
, 0);
2040 atomic_set(&cache
->stats
.promotion
, 0);
2041 atomic_set(&cache
->stats
.copies_avoided
, 0);
2042 atomic_set(&cache
->stats
.cache_cell_clash
, 0);
2043 atomic_set(&cache
->stats
.commit_count
, 0);
2044 atomic_set(&cache
->stats
.discard_count
, 0);
2054 static int copy_ctr_args(struct cache
*cache
, int argc
, const char **argv
)
2059 copy
= kcalloc(argc
, sizeof(*copy
), GFP_KERNEL
);
2062 for (i
= 0; i
< argc
; i
++) {
2063 copy
[i
] = kstrdup(argv
[i
], GFP_KERNEL
);
2072 cache
->nr_ctr_args
= argc
;
2073 cache
->ctr_args
= copy
;
2078 static int cache_ctr(struct dm_target
*ti
, unsigned argc
, char **argv
)
2081 struct cache_args
*ca
;
2082 struct cache
*cache
= NULL
;
2084 ca
= kzalloc(sizeof(*ca
), GFP_KERNEL
);
2086 ti
->error
= "Error allocating memory for cache";
2091 r
= parse_cache_args(ca
, argc
, argv
, &ti
->error
);
2095 r
= cache_create(ca
, &cache
);
2099 r
= copy_ctr_args(cache
, argc
- 3, (const char **)argv
+ 3);
2105 ti
->private = cache
;
2108 destroy_cache_args(ca
);
2112 static int cache_map(struct dm_target
*ti
, struct bio
*bio
)
2114 struct cache
*cache
= ti
->private;
2117 dm_oblock_t block
= get_bio_block(cache
, bio
);
2118 size_t pb_data_size
= get_per_bio_data_size(cache
);
2119 bool can_migrate
= false;
2120 bool discarded_block
;
2121 struct dm_bio_prison_cell
*cell
;
2122 struct policy_result lookup_result
;
2123 struct per_bio_data
*pb
;
2125 if (from_oblock(block
) > from_oblock(cache
->origin_blocks
)) {
2127 * This can only occur if the io goes to a partial block at
2128 * the end of the origin device. We don't cache these.
2129 * Just remap to the origin and carry on.
2131 remap_to_origin_clear_discard(cache
, bio
, block
);
2132 return DM_MAPIO_REMAPPED
;
2135 pb
= init_per_bio_data(bio
, pb_data_size
);
2137 if (bio
->bi_rw
& (REQ_FLUSH
| REQ_FUA
| REQ_DISCARD
)) {
2138 defer_bio(cache
, bio
);
2139 return DM_MAPIO_SUBMITTED
;
2143 * Check to see if that block is currently migrating.
2145 cell
= alloc_prison_cell(cache
);
2147 defer_bio(cache
, bio
);
2148 return DM_MAPIO_SUBMITTED
;
2151 r
= bio_detain(cache
, block
, bio
, cell
,
2152 (cell_free_fn
) free_prison_cell
,
2156 defer_bio(cache
, bio
);
2158 return DM_MAPIO_SUBMITTED
;
2161 discarded_block
= is_discarded_oblock(cache
, block
);
2163 r
= policy_map(cache
->policy
, block
, false, can_migrate
, discarded_block
,
2164 bio
, &lookup_result
);
2165 if (r
== -EWOULDBLOCK
) {
2166 cell_defer(cache
, cell
, true);
2167 return DM_MAPIO_SUBMITTED
;
2170 DMERR_LIMIT("Unexpected return from cache replacement policy: %d", r
);
2172 return DM_MAPIO_SUBMITTED
;
2175 switch (lookup_result
.op
) {
2177 inc_hit_counter(cache
, bio
);
2178 pb
->all_io_entry
= dm_deferred_entry_inc(cache
->all_io_ds
);
2180 if (is_writethrough_io(cache
, bio
, lookup_result
.cblock
))
2181 remap_to_origin_then_cache(cache
, bio
, block
, lookup_result
.cblock
);
2183 remap_to_cache_dirty(cache
, bio
, block
, lookup_result
.cblock
);
2185 cell_defer(cache
, cell
, false);
2189 inc_miss_counter(cache
, bio
);
2190 pb
->all_io_entry
= dm_deferred_entry_inc(cache
->all_io_ds
);
2192 if (pb
->req_nr
!= 0) {
2194 * This is a duplicate writethrough io that is no
2195 * longer needed because the block has been demoted.
2198 cell_defer(cache
, cell
, false);
2199 return DM_MAPIO_SUBMITTED
;
2201 remap_to_origin_clear_discard(cache
, bio
, block
);
2202 cell_defer(cache
, cell
, false);
2207 DMERR_LIMIT("%s: erroring bio: unknown policy op: %u", __func__
,
2208 (unsigned) lookup_result
.op
);
2210 return DM_MAPIO_SUBMITTED
;
2213 return DM_MAPIO_REMAPPED
;
2216 static int cache_end_io(struct dm_target
*ti
, struct bio
*bio
, int error
)
2218 struct cache
*cache
= ti
->private;
2219 unsigned long flags
;
2220 size_t pb_data_size
= get_per_bio_data_size(cache
);
2221 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
2224 policy_tick(cache
->policy
);
2226 spin_lock_irqsave(&cache
->lock
, flags
);
2227 cache
->need_tick_bio
= true;
2228 spin_unlock_irqrestore(&cache
->lock
, flags
);
2231 check_for_quiesced_migrations(cache
, pb
);
2236 static int write_dirty_bitset(struct cache
*cache
)
2240 for (i
= 0; i
< from_cblock(cache
->cache_size
); i
++) {
2241 r
= dm_cache_set_dirty(cache
->cmd
, to_cblock(i
),
2242 is_dirty(cache
, to_cblock(i
)));
2250 static int write_discard_bitset(struct cache
*cache
)
2254 r
= dm_cache_discard_bitset_resize(cache
->cmd
, cache
->discard_block_size
,
2255 cache
->discard_nr_blocks
);
2257 DMERR("could not resize on-disk discard bitset");
2261 for (i
= 0; i
< from_dblock(cache
->discard_nr_blocks
); i
++) {
2262 r
= dm_cache_set_discard(cache
->cmd
, to_dblock(i
),
2263 is_discarded(cache
, to_dblock(i
)));
2271 static int save_hint(void *context
, dm_cblock_t cblock
, dm_oblock_t oblock
,
2274 struct cache
*cache
= context
;
2275 return dm_cache_save_hint(cache
->cmd
, cblock
, hint
);
2278 static int write_hints(struct cache
*cache
)
2282 r
= dm_cache_begin_hints(cache
->cmd
, cache
->policy
);
2284 DMERR("dm_cache_begin_hints failed");
2288 r
= policy_walk_mappings(cache
->policy
, save_hint
, cache
);
2290 DMERR("policy_walk_mappings failed");
2296 * returns true on success
2298 static bool sync_metadata(struct cache
*cache
)
2302 r1
= write_dirty_bitset(cache
);
2304 DMERR("could not write dirty bitset");
2306 r2
= write_discard_bitset(cache
);
2308 DMERR("could not write discard bitset");
2312 r3
= write_hints(cache
);
2314 DMERR("could not write hints");
2317 * If writing the above metadata failed, we still commit, but don't
2318 * set the clean shutdown flag. This will effectively force every
2319 * dirty bit to be set on reload.
2321 r4
= dm_cache_commit(cache
->cmd
, !r1
&& !r2
&& !r3
);
2323 DMERR("could not write cache metadata. Data loss may occur.");
2325 return !r1
&& !r2
&& !r3
&& !r4
;
2328 static void cache_postsuspend(struct dm_target
*ti
)
2330 struct cache
*cache
= ti
->private;
2332 start_quiescing(cache
);
2333 wait_for_migrations(cache
);
2335 requeue_deferred_io(cache
);
2336 stop_quiescing(cache
);
2338 (void) sync_metadata(cache
);
2341 static int load_mapping(void *context
, dm_oblock_t oblock
, dm_cblock_t cblock
,
2342 bool dirty
, uint32_t hint
, bool hint_valid
)
2345 struct cache
*cache
= context
;
2347 r
= policy_load_mapping(cache
->policy
, oblock
, cblock
, hint
, hint_valid
);
2352 set_dirty(cache
, oblock
, cblock
);
2354 clear_dirty(cache
, oblock
, cblock
);
2359 static int load_discard(void *context
, sector_t discard_block_size
,
2360 dm_dblock_t dblock
, bool discard
)
2362 struct cache
*cache
= context
;
2364 /* FIXME: handle mis-matched block size */
2367 set_discard(cache
, dblock
);
2369 clear_discard(cache
, dblock
);
2374 static int cache_preresume(struct dm_target
*ti
)
2377 struct cache
*cache
= ti
->private;
2378 sector_t actual_cache_size
= get_dev_size(cache
->cache_dev
);
2379 (void) sector_div(actual_cache_size
, cache
->sectors_per_block
);
2382 * Check to see if the cache has resized.
2384 if (from_cblock(cache
->cache_size
) != actual_cache_size
|| !cache
->sized
) {
2385 cache
->cache_size
= to_cblock(actual_cache_size
);
2387 r
= dm_cache_resize(cache
->cmd
, cache
->cache_size
);
2389 DMERR("could not resize cache metadata");
2393 cache
->sized
= true;
2396 if (!cache
->loaded_mappings
) {
2397 r
= dm_cache_load_mappings(cache
->cmd
, cache
->policy
,
2398 load_mapping
, cache
);
2400 DMERR("could not load cache mappings");
2404 cache
->loaded_mappings
= true;
2407 if (!cache
->loaded_discards
) {
2408 r
= dm_cache_load_discards(cache
->cmd
, load_discard
, cache
);
2410 DMERR("could not load origin discards");
2414 cache
->loaded_discards
= true;
2420 static void cache_resume(struct dm_target
*ti
)
2422 struct cache
*cache
= ti
->private;
2424 cache
->need_tick_bio
= true;
2425 do_waker(&cache
->waker
.work
);
2431 * <#used metadata blocks>/<#total metadata blocks>
2432 * <#read hits> <#read misses> <#write hits> <#write misses>
2433 * <#demotions> <#promotions> <#blocks in cache> <#dirty>
2434 * <#features> <features>*
2435 * <#core args> <core args>
2436 * <#policy args> <policy args>*
2438 static void cache_status(struct dm_target
*ti
, status_type_t type
,
2439 unsigned status_flags
, char *result
, unsigned maxlen
)
2444 dm_block_t nr_free_blocks_metadata
= 0;
2445 dm_block_t nr_blocks_metadata
= 0;
2446 char buf
[BDEVNAME_SIZE
];
2447 struct cache
*cache
= ti
->private;
2448 dm_cblock_t residency
;
2451 case STATUSTYPE_INFO
:
2452 /* Commit to ensure statistics aren't out-of-date */
2453 if (!(status_flags
& DM_STATUS_NOFLUSH_FLAG
) && !dm_suspended(ti
)) {
2454 r
= dm_cache_commit(cache
->cmd
, false);
2456 DMERR("could not commit metadata for accurate status");
2459 r
= dm_cache_get_free_metadata_block_count(cache
->cmd
,
2460 &nr_free_blocks_metadata
);
2462 DMERR("could not get metadata free block count");
2466 r
= dm_cache_get_metadata_dev_size(cache
->cmd
, &nr_blocks_metadata
);
2468 DMERR("could not get metadata device size");
2472 residency
= policy_residency(cache
->policy
);
2474 DMEMIT("%llu/%llu %u %u %u %u %u %u %llu %u ",
2475 (unsigned long long)(nr_blocks_metadata
- nr_free_blocks_metadata
),
2476 (unsigned long long)nr_blocks_metadata
,
2477 (unsigned) atomic_read(&cache
->stats
.read_hit
),
2478 (unsigned) atomic_read(&cache
->stats
.read_miss
),
2479 (unsigned) atomic_read(&cache
->stats
.write_hit
),
2480 (unsigned) atomic_read(&cache
->stats
.write_miss
),
2481 (unsigned) atomic_read(&cache
->stats
.demotion
),
2482 (unsigned) atomic_read(&cache
->stats
.promotion
),
2483 (unsigned long long) from_cblock(residency
),
2486 if (cache
->features
.write_through
)
2487 DMEMIT("1 writethrough ");
2491 DMEMIT("2 migration_threshold %llu ", (unsigned long long) cache
->migration_threshold
);
2493 r
= policy_emit_config_values(cache
->policy
, result
+ sz
, maxlen
- sz
);
2495 DMERR("policy_emit_config_values returned %d", r
);
2500 case STATUSTYPE_TABLE
:
2501 format_dev_t(buf
, cache
->metadata_dev
->bdev
->bd_dev
);
2503 format_dev_t(buf
, cache
->cache_dev
->bdev
->bd_dev
);
2505 format_dev_t(buf
, cache
->origin_dev
->bdev
->bd_dev
);
2508 for (i
= 0; i
< cache
->nr_ctr_args
- 1; i
++)
2509 DMEMIT(" %s", cache
->ctr_args
[i
]);
2510 if (cache
->nr_ctr_args
)
2511 DMEMIT(" %s", cache
->ctr_args
[cache
->nr_ctr_args
- 1]);
2520 #define NOT_CORE_OPTION 1
2522 static int process_config_option(struct cache
*cache
, char **argv
)
2526 if (!strcasecmp(argv
[0], "migration_threshold")) {
2527 if (kstrtoul(argv
[1], 10, &tmp
))
2530 cache
->migration_threshold
= tmp
;
2534 return NOT_CORE_OPTION
;
2538 * Supports <key> <value>.
2540 * The key migration_threshold is supported by the cache target core.
2542 static int cache_message(struct dm_target
*ti
, unsigned argc
, char **argv
)
2545 struct cache
*cache
= ti
->private;
2550 r
= process_config_option(cache
, argv
);
2551 if (r
== NOT_CORE_OPTION
)
2552 return policy_set_config_value(cache
->policy
, argv
[0], argv
[1]);
2557 static int cache_iterate_devices(struct dm_target
*ti
,
2558 iterate_devices_callout_fn fn
, void *data
)
2561 struct cache
*cache
= ti
->private;
2563 r
= fn(ti
, cache
->cache_dev
, 0, get_dev_size(cache
->cache_dev
), data
);
2565 r
= fn(ti
, cache
->origin_dev
, 0, ti
->len
, data
);
2571 * We assume I/O is going to the origin (which is the volume
2572 * more likely to have restrictions e.g. by being striped).
2573 * (Looking up the exact location of the data would be expensive
2574 * and could always be out of date by the time the bio is submitted.)
2576 static int cache_bvec_merge(struct dm_target
*ti
,
2577 struct bvec_merge_data
*bvm
,
2578 struct bio_vec
*biovec
, int max_size
)
2580 struct cache
*cache
= ti
->private;
2581 struct request_queue
*q
= bdev_get_queue(cache
->origin_dev
->bdev
);
2583 if (!q
->merge_bvec_fn
)
2586 bvm
->bi_bdev
= cache
->origin_dev
->bdev
;
2587 return min(max_size
, q
->merge_bvec_fn(q
, bvm
, biovec
));
2590 static void set_discard_limits(struct cache
*cache
, struct queue_limits
*limits
)
2593 * FIXME: these limits may be incompatible with the cache device
2595 limits
->max_discard_sectors
= cache
->discard_block_size
* 1024;
2596 limits
->discard_granularity
= cache
->discard_block_size
<< SECTOR_SHIFT
;
2599 static void cache_io_hints(struct dm_target
*ti
, struct queue_limits
*limits
)
2601 struct cache
*cache
= ti
->private;
2603 blk_limits_io_min(limits
, 0);
2604 blk_limits_io_opt(limits
, cache
->sectors_per_block
<< SECTOR_SHIFT
);
2605 set_discard_limits(cache
, limits
);
2608 /*----------------------------------------------------------------*/
2610 static struct target_type cache_target
= {
2612 .version
= {1, 1, 0},
2613 .module
= THIS_MODULE
,
2617 .end_io
= cache_end_io
,
2618 .postsuspend
= cache_postsuspend
,
2619 .preresume
= cache_preresume
,
2620 .resume
= cache_resume
,
2621 .status
= cache_status
,
2622 .message
= cache_message
,
2623 .iterate_devices
= cache_iterate_devices
,
2624 .merge
= cache_bvec_merge
,
2625 .io_hints
= cache_io_hints
,
2628 static int __init
dm_cache_init(void)
2632 r
= dm_register_target(&cache_target
);
2634 DMERR("cache target registration failed: %d", r
);
2638 migration_cache
= KMEM_CACHE(dm_cache_migration
, 0);
2639 if (!migration_cache
) {
2640 dm_unregister_target(&cache_target
);
2647 static void __exit
dm_cache_exit(void)
2649 dm_unregister_target(&cache_target
);
2650 kmem_cache_destroy(migration_cache
);
2653 module_init(dm_cache_init
);
2654 module_exit(dm_cache_exit
);
2656 MODULE_DESCRIPTION(DM_NAME
" cache target");
2657 MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
2658 MODULE_LICENSE("GPL");