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 offset of 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 /*----------------------------------------------------------------*/
423 static bool block_size_is_power_of_two(struct cache
*cache
)
425 return cache
->sectors_per_block_shift
>= 0;
428 /* gcc on ARM generates spurious references to __udivdi3 and __umoddi3 */
429 #if defined(CONFIG_ARM) && __GNUC__ == 4 && __GNUC_MINOR__ <= 6
432 static dm_block_t
block_div(dm_block_t b
, uint32_t n
)
439 static dm_dblock_t
oblock_to_dblock(struct cache
*cache
, dm_oblock_t oblock
)
441 uint32_t discard_blocks
= cache
->discard_block_size
;
442 dm_block_t b
= from_oblock(oblock
);
444 if (!block_size_is_power_of_two(cache
))
445 discard_blocks
= discard_blocks
/ cache
->sectors_per_block
;
447 discard_blocks
>>= cache
->sectors_per_block_shift
;
449 b
= block_div(b
, discard_blocks
);
454 static void set_discard(struct cache
*cache
, dm_dblock_t b
)
458 atomic_inc(&cache
->stats
.discard_count
);
460 spin_lock_irqsave(&cache
->lock
, flags
);
461 set_bit(from_dblock(b
), cache
->discard_bitset
);
462 spin_unlock_irqrestore(&cache
->lock
, flags
);
465 static void clear_discard(struct cache
*cache
, dm_dblock_t b
)
469 spin_lock_irqsave(&cache
->lock
, flags
);
470 clear_bit(from_dblock(b
), cache
->discard_bitset
);
471 spin_unlock_irqrestore(&cache
->lock
, flags
);
474 static bool is_discarded(struct cache
*cache
, dm_dblock_t b
)
479 spin_lock_irqsave(&cache
->lock
, flags
);
480 r
= test_bit(from_dblock(b
), cache
->discard_bitset
);
481 spin_unlock_irqrestore(&cache
->lock
, flags
);
486 static bool is_discarded_oblock(struct cache
*cache
, dm_oblock_t b
)
491 spin_lock_irqsave(&cache
->lock
, flags
);
492 r
= test_bit(from_dblock(oblock_to_dblock(cache
, b
)),
493 cache
->discard_bitset
);
494 spin_unlock_irqrestore(&cache
->lock
, flags
);
499 /*----------------------------------------------------------------*/
501 static void load_stats(struct cache
*cache
)
503 struct dm_cache_statistics stats
;
505 dm_cache_metadata_get_stats(cache
->cmd
, &stats
);
506 atomic_set(&cache
->stats
.read_hit
, stats
.read_hits
);
507 atomic_set(&cache
->stats
.read_miss
, stats
.read_misses
);
508 atomic_set(&cache
->stats
.write_hit
, stats
.write_hits
);
509 atomic_set(&cache
->stats
.write_miss
, stats
.write_misses
);
512 static void save_stats(struct cache
*cache
)
514 struct dm_cache_statistics stats
;
516 stats
.read_hits
= atomic_read(&cache
->stats
.read_hit
);
517 stats
.read_misses
= atomic_read(&cache
->stats
.read_miss
);
518 stats
.write_hits
= atomic_read(&cache
->stats
.write_hit
);
519 stats
.write_misses
= atomic_read(&cache
->stats
.write_miss
);
521 dm_cache_metadata_set_stats(cache
->cmd
, &stats
);
524 /*----------------------------------------------------------------
526 *--------------------------------------------------------------*/
529 * If using writeback, leave out struct per_bio_data's writethrough fields.
531 #define PB_DATA_SIZE_WB (offsetof(struct per_bio_data, cache))
532 #define PB_DATA_SIZE_WT (sizeof(struct per_bio_data))
534 static size_t get_per_bio_data_size(struct cache
*cache
)
536 return cache
->features
.write_through
? PB_DATA_SIZE_WT
: PB_DATA_SIZE_WB
;
539 static struct per_bio_data
*get_per_bio_data(struct bio
*bio
, size_t data_size
)
541 struct per_bio_data
*pb
= dm_per_bio_data(bio
, data_size
);
546 static struct per_bio_data
*init_per_bio_data(struct bio
*bio
, size_t data_size
)
548 struct per_bio_data
*pb
= get_per_bio_data(bio
, data_size
);
551 pb
->req_nr
= dm_bio_get_target_bio_nr(bio
);
552 pb
->all_io_entry
= NULL
;
557 /*----------------------------------------------------------------
559 *--------------------------------------------------------------*/
560 static void remap_to_origin(struct cache
*cache
, struct bio
*bio
)
562 bio
->bi_bdev
= cache
->origin_dev
->bdev
;
565 static void remap_to_cache(struct cache
*cache
, struct bio
*bio
,
568 sector_t bi_sector
= bio
->bi_sector
;
570 bio
->bi_bdev
= cache
->cache_dev
->bdev
;
571 if (!block_size_is_power_of_two(cache
))
572 bio
->bi_sector
= (from_cblock(cblock
) * cache
->sectors_per_block
) +
573 sector_div(bi_sector
, cache
->sectors_per_block
);
575 bio
->bi_sector
= (from_cblock(cblock
) << cache
->sectors_per_block_shift
) |
576 (bi_sector
& (cache
->sectors_per_block
- 1));
579 static void check_if_tick_bio_needed(struct cache
*cache
, struct bio
*bio
)
582 size_t pb_data_size
= get_per_bio_data_size(cache
);
583 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
585 spin_lock_irqsave(&cache
->lock
, flags
);
586 if (cache
->need_tick_bio
&&
587 !(bio
->bi_rw
& (REQ_FUA
| REQ_FLUSH
| REQ_DISCARD
))) {
589 cache
->need_tick_bio
= false;
591 spin_unlock_irqrestore(&cache
->lock
, flags
);
594 static void remap_to_origin_clear_discard(struct cache
*cache
, struct bio
*bio
,
597 check_if_tick_bio_needed(cache
, bio
);
598 remap_to_origin(cache
, bio
);
599 if (bio_data_dir(bio
) == WRITE
)
600 clear_discard(cache
, oblock_to_dblock(cache
, oblock
));
603 static void remap_to_cache_dirty(struct cache
*cache
, struct bio
*bio
,
604 dm_oblock_t oblock
, dm_cblock_t cblock
)
606 remap_to_cache(cache
, bio
, cblock
);
607 if (bio_data_dir(bio
) == WRITE
) {
608 set_dirty(cache
, oblock
, cblock
);
609 clear_discard(cache
, oblock_to_dblock(cache
, oblock
));
613 static dm_oblock_t
get_bio_block(struct cache
*cache
, struct bio
*bio
)
615 sector_t block_nr
= bio
->bi_sector
;
617 if (!block_size_is_power_of_two(cache
))
618 (void) sector_div(block_nr
, cache
->sectors_per_block
);
620 block_nr
>>= cache
->sectors_per_block_shift
;
622 return to_oblock(block_nr
);
625 static int bio_triggers_commit(struct cache
*cache
, struct bio
*bio
)
627 return bio
->bi_rw
& (REQ_FLUSH
| REQ_FUA
);
630 static void issue(struct cache
*cache
, struct bio
*bio
)
634 if (!bio_triggers_commit(cache
, bio
)) {
635 generic_make_request(bio
);
640 * Batch together any bios that trigger commits and then issue a
641 * single commit for them in do_worker().
643 spin_lock_irqsave(&cache
->lock
, flags
);
644 cache
->commit_requested
= true;
645 bio_list_add(&cache
->deferred_flush_bios
, bio
);
646 spin_unlock_irqrestore(&cache
->lock
, flags
);
649 static void defer_writethrough_bio(struct cache
*cache
, struct bio
*bio
)
653 spin_lock_irqsave(&cache
->lock
, flags
);
654 bio_list_add(&cache
->deferred_writethrough_bios
, bio
);
655 spin_unlock_irqrestore(&cache
->lock
, flags
);
660 static void writethrough_endio(struct bio
*bio
, int err
)
662 struct per_bio_data
*pb
= get_per_bio_data(bio
, PB_DATA_SIZE_WT
);
663 bio
->bi_end_io
= pb
->saved_bi_end_io
;
670 dm_bio_restore(&pb
->bio_details
, bio
);
671 remap_to_cache(pb
->cache
, bio
, pb
->cblock
);
674 * We can't issue this bio directly, since we're in interrupt
675 * context. So it gets put on a bio list for processing by the
678 defer_writethrough_bio(pb
->cache
, bio
);
682 * When running in writethrough mode we need to send writes to clean blocks
683 * to both the cache and origin devices. In future we'd like to clone the
684 * bio and send them in parallel, but for now we're doing them in
685 * series as this is easier.
687 static void remap_to_origin_then_cache(struct cache
*cache
, struct bio
*bio
,
688 dm_oblock_t oblock
, dm_cblock_t cblock
)
690 struct per_bio_data
*pb
= get_per_bio_data(bio
, PB_DATA_SIZE_WT
);
694 pb
->saved_bi_end_io
= bio
->bi_end_io
;
695 dm_bio_record(&pb
->bio_details
, bio
);
696 bio
->bi_end_io
= writethrough_endio
;
698 remap_to_origin_clear_discard(pb
->cache
, bio
, oblock
);
701 /*----------------------------------------------------------------
702 * Migration processing
704 * Migration covers moving data from the origin device to the cache, or
706 *--------------------------------------------------------------*/
707 static void free_migration(struct dm_cache_migration
*mg
)
709 mempool_free(mg
, mg
->cache
->migration_pool
);
712 static void inc_nr_migrations(struct cache
*cache
)
714 atomic_inc(&cache
->nr_migrations
);
717 static void dec_nr_migrations(struct cache
*cache
)
719 atomic_dec(&cache
->nr_migrations
);
722 * Wake the worker in case we're suspending the target.
724 wake_up(&cache
->migration_wait
);
727 static void __cell_defer(struct cache
*cache
, struct dm_bio_prison_cell
*cell
,
730 (holder
? dm_cell_release
: dm_cell_release_no_holder
)
731 (cache
->prison
, cell
, &cache
->deferred_bios
);
732 free_prison_cell(cache
, cell
);
735 static void cell_defer(struct cache
*cache
, struct dm_bio_prison_cell
*cell
,
740 spin_lock_irqsave(&cache
->lock
, flags
);
741 __cell_defer(cache
, cell
, holder
);
742 spin_unlock_irqrestore(&cache
->lock
, flags
);
747 static void cleanup_migration(struct dm_cache_migration
*mg
)
749 dec_nr_migrations(mg
->cache
);
753 static void migration_failure(struct dm_cache_migration
*mg
)
755 struct cache
*cache
= mg
->cache
;
758 DMWARN_LIMIT("writeback failed; couldn't copy block");
759 set_dirty(cache
, mg
->old_oblock
, mg
->cblock
);
760 cell_defer(cache
, mg
->old_ocell
, false);
762 } else if (mg
->demote
) {
763 DMWARN_LIMIT("demotion failed; couldn't copy block");
764 policy_force_mapping(cache
->policy
, mg
->new_oblock
, mg
->old_oblock
);
766 cell_defer(cache
, mg
->old_ocell
, mg
->promote
? 0 : 1);
768 cell_defer(cache
, mg
->new_ocell
, 1);
770 DMWARN_LIMIT("promotion failed; couldn't copy block");
771 policy_remove_mapping(cache
->policy
, mg
->new_oblock
);
772 cell_defer(cache
, mg
->new_ocell
, 1);
775 cleanup_migration(mg
);
778 static void migration_success_pre_commit(struct dm_cache_migration
*mg
)
781 struct cache
*cache
= mg
->cache
;
784 cell_defer(cache
, mg
->old_ocell
, false);
785 clear_dirty(cache
, mg
->old_oblock
, mg
->cblock
);
786 cleanup_migration(mg
);
789 } else if (mg
->demote
) {
790 if (dm_cache_remove_mapping(cache
->cmd
, mg
->cblock
)) {
791 DMWARN_LIMIT("demotion failed; couldn't update on disk metadata");
792 policy_force_mapping(cache
->policy
, mg
->new_oblock
,
795 cell_defer(cache
, mg
->new_ocell
, true);
796 cleanup_migration(mg
);
800 if (dm_cache_insert_mapping(cache
->cmd
, mg
->cblock
, mg
->new_oblock
)) {
801 DMWARN_LIMIT("promotion failed; couldn't update on disk metadata");
802 policy_remove_mapping(cache
->policy
, mg
->new_oblock
);
803 cleanup_migration(mg
);
808 spin_lock_irqsave(&cache
->lock
, flags
);
809 list_add_tail(&mg
->list
, &cache
->need_commit_migrations
);
810 cache
->commit_requested
= true;
811 spin_unlock_irqrestore(&cache
->lock
, flags
);
814 static void migration_success_post_commit(struct dm_cache_migration
*mg
)
817 struct cache
*cache
= mg
->cache
;
820 DMWARN("writeback unexpectedly triggered commit");
823 } else if (mg
->demote
) {
824 cell_defer(cache
, mg
->old_ocell
, mg
->promote
? 0 : 1);
829 spin_lock_irqsave(&cache
->lock
, flags
);
830 list_add_tail(&mg
->list
, &cache
->quiesced_migrations
);
831 spin_unlock_irqrestore(&cache
->lock
, flags
);
834 cleanup_migration(mg
);
837 cell_defer(cache
, mg
->new_ocell
, true);
838 clear_dirty(cache
, mg
->new_oblock
, mg
->cblock
);
839 cleanup_migration(mg
);
843 static void copy_complete(int read_err
, unsigned long write_err
, void *context
)
846 struct dm_cache_migration
*mg
= (struct dm_cache_migration
*) context
;
847 struct cache
*cache
= mg
->cache
;
849 if (read_err
|| write_err
)
852 spin_lock_irqsave(&cache
->lock
, flags
);
853 list_add_tail(&mg
->list
, &cache
->completed_migrations
);
854 spin_unlock_irqrestore(&cache
->lock
, flags
);
859 static void issue_copy_real(struct dm_cache_migration
*mg
)
862 struct dm_io_region o_region
, c_region
;
863 struct cache
*cache
= mg
->cache
;
865 o_region
.bdev
= cache
->origin_dev
->bdev
;
866 o_region
.count
= cache
->sectors_per_block
;
868 c_region
.bdev
= cache
->cache_dev
->bdev
;
869 c_region
.sector
= from_cblock(mg
->cblock
) * cache
->sectors_per_block
;
870 c_region
.count
= cache
->sectors_per_block
;
872 if (mg
->writeback
|| mg
->demote
) {
874 o_region
.sector
= from_oblock(mg
->old_oblock
) * cache
->sectors_per_block
;
875 r
= dm_kcopyd_copy(cache
->copier
, &c_region
, 1, &o_region
, 0, copy_complete
, mg
);
878 o_region
.sector
= from_oblock(mg
->new_oblock
) * cache
->sectors_per_block
;
879 r
= dm_kcopyd_copy(cache
->copier
, &o_region
, 1, &c_region
, 0, copy_complete
, mg
);
883 migration_failure(mg
);
886 static void avoid_copy(struct dm_cache_migration
*mg
)
888 atomic_inc(&mg
->cache
->stats
.copies_avoided
);
889 migration_success_pre_commit(mg
);
892 static void issue_copy(struct dm_cache_migration
*mg
)
895 struct cache
*cache
= mg
->cache
;
897 if (mg
->writeback
|| mg
->demote
)
898 avoid
= !is_dirty(cache
, mg
->cblock
) ||
899 is_discarded_oblock(cache
, mg
->old_oblock
);
901 avoid
= is_discarded_oblock(cache
, mg
->new_oblock
);
903 avoid
? avoid_copy(mg
) : issue_copy_real(mg
);
906 static void complete_migration(struct dm_cache_migration
*mg
)
909 migration_failure(mg
);
911 migration_success_pre_commit(mg
);
914 static void process_migrations(struct cache
*cache
, struct list_head
*head
,
915 void (*fn
)(struct dm_cache_migration
*))
918 struct list_head list
;
919 struct dm_cache_migration
*mg
, *tmp
;
921 INIT_LIST_HEAD(&list
);
922 spin_lock_irqsave(&cache
->lock
, flags
);
923 list_splice_init(head
, &list
);
924 spin_unlock_irqrestore(&cache
->lock
, flags
);
926 list_for_each_entry_safe(mg
, tmp
, &list
, list
)
930 static void __queue_quiesced_migration(struct dm_cache_migration
*mg
)
932 list_add_tail(&mg
->list
, &mg
->cache
->quiesced_migrations
);
935 static void queue_quiesced_migration(struct dm_cache_migration
*mg
)
938 struct cache
*cache
= mg
->cache
;
940 spin_lock_irqsave(&cache
->lock
, flags
);
941 __queue_quiesced_migration(mg
);
942 spin_unlock_irqrestore(&cache
->lock
, flags
);
947 static void queue_quiesced_migrations(struct cache
*cache
, struct list_head
*work
)
950 struct dm_cache_migration
*mg
, *tmp
;
952 spin_lock_irqsave(&cache
->lock
, flags
);
953 list_for_each_entry_safe(mg
, tmp
, work
, list
)
954 __queue_quiesced_migration(mg
);
955 spin_unlock_irqrestore(&cache
->lock
, flags
);
960 static void check_for_quiesced_migrations(struct cache
*cache
,
961 struct per_bio_data
*pb
)
963 struct list_head work
;
965 if (!pb
->all_io_entry
)
968 INIT_LIST_HEAD(&work
);
969 if (pb
->all_io_entry
)
970 dm_deferred_entry_dec(pb
->all_io_entry
, &work
);
972 if (!list_empty(&work
))
973 queue_quiesced_migrations(cache
, &work
);
976 static void quiesce_migration(struct dm_cache_migration
*mg
)
978 if (!dm_deferred_set_add_work(mg
->cache
->all_io_ds
, &mg
->list
))
979 queue_quiesced_migration(mg
);
982 static void promote(struct cache
*cache
, struct prealloc
*structs
,
983 dm_oblock_t oblock
, dm_cblock_t cblock
,
984 struct dm_bio_prison_cell
*cell
)
986 struct dm_cache_migration
*mg
= prealloc_get_migration(structs
);
989 mg
->writeback
= false;
993 mg
->new_oblock
= oblock
;
995 mg
->old_ocell
= NULL
;
996 mg
->new_ocell
= cell
;
997 mg
->start_jiffies
= jiffies
;
999 inc_nr_migrations(cache
);
1000 quiesce_migration(mg
);
1003 static void writeback(struct cache
*cache
, struct prealloc
*structs
,
1004 dm_oblock_t oblock
, dm_cblock_t cblock
,
1005 struct dm_bio_prison_cell
*cell
)
1007 struct dm_cache_migration
*mg
= prealloc_get_migration(structs
);
1010 mg
->writeback
= true;
1012 mg
->promote
= false;
1014 mg
->old_oblock
= oblock
;
1015 mg
->cblock
= cblock
;
1016 mg
->old_ocell
= cell
;
1017 mg
->new_ocell
= NULL
;
1018 mg
->start_jiffies
= jiffies
;
1020 inc_nr_migrations(cache
);
1021 quiesce_migration(mg
);
1024 static void demote_then_promote(struct cache
*cache
, struct prealloc
*structs
,
1025 dm_oblock_t old_oblock
, dm_oblock_t new_oblock
,
1027 struct dm_bio_prison_cell
*old_ocell
,
1028 struct dm_bio_prison_cell
*new_ocell
)
1030 struct dm_cache_migration
*mg
= prealloc_get_migration(structs
);
1033 mg
->writeback
= false;
1037 mg
->old_oblock
= old_oblock
;
1038 mg
->new_oblock
= new_oblock
;
1039 mg
->cblock
= cblock
;
1040 mg
->old_ocell
= old_ocell
;
1041 mg
->new_ocell
= new_ocell
;
1042 mg
->start_jiffies
= jiffies
;
1044 inc_nr_migrations(cache
);
1045 quiesce_migration(mg
);
1048 /*----------------------------------------------------------------
1050 *--------------------------------------------------------------*/
1051 static void defer_bio(struct cache
*cache
, struct bio
*bio
)
1053 unsigned long flags
;
1055 spin_lock_irqsave(&cache
->lock
, flags
);
1056 bio_list_add(&cache
->deferred_bios
, bio
);
1057 spin_unlock_irqrestore(&cache
->lock
, flags
);
1062 static void process_flush_bio(struct cache
*cache
, struct bio
*bio
)
1064 size_t pb_data_size
= get_per_bio_data_size(cache
);
1065 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
1067 BUG_ON(bio
->bi_size
);
1069 remap_to_origin(cache
, bio
);
1071 remap_to_cache(cache
, bio
, 0);
1077 * People generally discard large parts of a device, eg, the whole device
1078 * when formatting. Splitting these large discards up into cache block
1079 * sized ios and then quiescing (always neccessary for discard) takes too
1082 * We keep it simple, and allow any size of discard to come in, and just
1083 * mark off blocks on the discard bitset. No passdown occurs!
1085 * To implement passdown we need to change the bio_prison such that a cell
1086 * can have a key that spans many blocks.
1088 static void process_discard_bio(struct cache
*cache
, struct bio
*bio
)
1090 dm_block_t start_block
= dm_sector_div_up(bio
->bi_sector
,
1091 cache
->discard_block_size
);
1092 dm_block_t end_block
= bio
->bi_sector
+ bio_sectors(bio
);
1095 end_block
= block_div(end_block
, cache
->discard_block_size
);
1097 for (b
= start_block
; b
< end_block
; b
++)
1098 set_discard(cache
, to_dblock(b
));
1103 static bool spare_migration_bandwidth(struct cache
*cache
)
1105 sector_t current_volume
= (atomic_read(&cache
->nr_migrations
) + 1) *
1106 cache
->sectors_per_block
;
1107 return current_volume
< cache
->migration_threshold
;
1110 static bool is_writethrough_io(struct cache
*cache
, struct bio
*bio
,
1113 return bio_data_dir(bio
) == WRITE
&&
1114 cache
->features
.write_through
&& !is_dirty(cache
, cblock
);
1117 static void inc_hit_counter(struct cache
*cache
, struct bio
*bio
)
1119 atomic_inc(bio_data_dir(bio
) == READ
?
1120 &cache
->stats
.read_hit
: &cache
->stats
.write_hit
);
1123 static void inc_miss_counter(struct cache
*cache
, struct bio
*bio
)
1125 atomic_inc(bio_data_dir(bio
) == READ
?
1126 &cache
->stats
.read_miss
: &cache
->stats
.write_miss
);
1129 static void process_bio(struct cache
*cache
, struct prealloc
*structs
,
1133 bool release_cell
= true;
1134 dm_oblock_t block
= get_bio_block(cache
, bio
);
1135 struct dm_bio_prison_cell
*cell_prealloc
, *old_ocell
, *new_ocell
;
1136 struct policy_result lookup_result
;
1137 size_t pb_data_size
= get_per_bio_data_size(cache
);
1138 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
1139 bool discarded_block
= is_discarded_oblock(cache
, block
);
1140 bool can_migrate
= discarded_block
|| spare_migration_bandwidth(cache
);
1143 * Check to see if that block is currently migrating.
1145 cell_prealloc
= prealloc_get_cell(structs
);
1146 r
= bio_detain(cache
, block
, bio
, cell_prealloc
,
1147 (cell_free_fn
) prealloc_put_cell
,
1148 structs
, &new_ocell
);
1152 r
= policy_map(cache
->policy
, block
, true, can_migrate
, discarded_block
,
1153 bio
, &lookup_result
);
1155 if (r
== -EWOULDBLOCK
)
1156 /* migration has been denied */
1157 lookup_result
.op
= POLICY_MISS
;
1159 switch (lookup_result
.op
) {
1161 inc_hit_counter(cache
, bio
);
1162 pb
->all_io_entry
= dm_deferred_entry_inc(cache
->all_io_ds
);
1164 if (is_writethrough_io(cache
, bio
, lookup_result
.cblock
))
1165 remap_to_origin_then_cache(cache
, bio
, block
, lookup_result
.cblock
);
1167 remap_to_cache_dirty(cache
, bio
, block
, lookup_result
.cblock
);
1173 inc_miss_counter(cache
, bio
);
1174 pb
->all_io_entry
= dm_deferred_entry_inc(cache
->all_io_ds
);
1175 remap_to_origin_clear_discard(cache
, bio
, block
);
1180 atomic_inc(&cache
->stats
.promotion
);
1181 promote(cache
, structs
, block
, lookup_result
.cblock
, new_ocell
);
1182 release_cell
= false;
1185 case POLICY_REPLACE
:
1186 cell_prealloc
= prealloc_get_cell(structs
);
1187 r
= bio_detain(cache
, lookup_result
.old_oblock
, bio
, cell_prealloc
,
1188 (cell_free_fn
) prealloc_put_cell
,
1189 structs
, &old_ocell
);
1192 * We have to be careful to avoid lock inversion of
1193 * the cells. So we back off, and wait for the
1194 * old_ocell to become free.
1196 policy_force_mapping(cache
->policy
, block
,
1197 lookup_result
.old_oblock
);
1198 atomic_inc(&cache
->stats
.cache_cell_clash
);
1201 atomic_inc(&cache
->stats
.demotion
);
1202 atomic_inc(&cache
->stats
.promotion
);
1204 demote_then_promote(cache
, structs
, lookup_result
.old_oblock
,
1205 block
, lookup_result
.cblock
,
1206 old_ocell
, new_ocell
);
1207 release_cell
= false;
1211 DMERR_LIMIT("%s: erroring bio, unknown policy op: %u", __func__
,
1212 (unsigned) lookup_result
.op
);
1217 cell_defer(cache
, new_ocell
, false);
1220 static int need_commit_due_to_time(struct cache
*cache
)
1222 return jiffies
< cache
->last_commit_jiffies
||
1223 jiffies
> cache
->last_commit_jiffies
+ COMMIT_PERIOD
;
1226 static int commit_if_needed(struct cache
*cache
)
1228 if (dm_cache_changed_this_transaction(cache
->cmd
) &&
1229 (cache
->commit_requested
|| need_commit_due_to_time(cache
))) {
1230 atomic_inc(&cache
->stats
.commit_count
);
1231 cache
->last_commit_jiffies
= jiffies
;
1232 cache
->commit_requested
= false;
1233 return dm_cache_commit(cache
->cmd
, false);
1239 static void process_deferred_bios(struct cache
*cache
)
1241 unsigned long flags
;
1242 struct bio_list bios
;
1244 struct prealloc structs
;
1246 memset(&structs
, 0, sizeof(structs
));
1247 bio_list_init(&bios
);
1249 spin_lock_irqsave(&cache
->lock
, flags
);
1250 bio_list_merge(&bios
, &cache
->deferred_bios
);
1251 bio_list_init(&cache
->deferred_bios
);
1252 spin_unlock_irqrestore(&cache
->lock
, flags
);
1254 while (!bio_list_empty(&bios
)) {
1256 * If we've got no free migration structs, and processing
1257 * this bio might require one, we pause until there are some
1258 * prepared mappings to process.
1260 if (prealloc_data_structs(cache
, &structs
)) {
1261 spin_lock_irqsave(&cache
->lock
, flags
);
1262 bio_list_merge(&cache
->deferred_bios
, &bios
);
1263 spin_unlock_irqrestore(&cache
->lock
, flags
);
1267 bio
= bio_list_pop(&bios
);
1269 if (bio
->bi_rw
& REQ_FLUSH
)
1270 process_flush_bio(cache
, bio
);
1271 else if (bio
->bi_rw
& REQ_DISCARD
)
1272 process_discard_bio(cache
, bio
);
1274 process_bio(cache
, &structs
, bio
);
1277 prealloc_free_structs(cache
, &structs
);
1280 static void process_deferred_flush_bios(struct cache
*cache
, bool submit_bios
)
1282 unsigned long flags
;
1283 struct bio_list bios
;
1286 bio_list_init(&bios
);
1288 spin_lock_irqsave(&cache
->lock
, flags
);
1289 bio_list_merge(&bios
, &cache
->deferred_flush_bios
);
1290 bio_list_init(&cache
->deferred_flush_bios
);
1291 spin_unlock_irqrestore(&cache
->lock
, flags
);
1293 while ((bio
= bio_list_pop(&bios
)))
1294 submit_bios
? generic_make_request(bio
) : bio_io_error(bio
);
1297 static void process_deferred_writethrough_bios(struct cache
*cache
)
1299 unsigned long flags
;
1300 struct bio_list bios
;
1303 bio_list_init(&bios
);
1305 spin_lock_irqsave(&cache
->lock
, flags
);
1306 bio_list_merge(&bios
, &cache
->deferred_writethrough_bios
);
1307 bio_list_init(&cache
->deferred_writethrough_bios
);
1308 spin_unlock_irqrestore(&cache
->lock
, flags
);
1310 while ((bio
= bio_list_pop(&bios
)))
1311 generic_make_request(bio
);
1314 static void writeback_some_dirty_blocks(struct cache
*cache
)
1319 struct prealloc structs
;
1320 struct dm_bio_prison_cell
*old_ocell
;
1322 memset(&structs
, 0, sizeof(structs
));
1324 while (spare_migration_bandwidth(cache
)) {
1325 if (prealloc_data_structs(cache
, &structs
))
1328 r
= policy_writeback_work(cache
->policy
, &oblock
, &cblock
);
1332 r
= get_cell(cache
, oblock
, &structs
, &old_ocell
);
1334 policy_set_dirty(cache
->policy
, oblock
);
1338 writeback(cache
, &structs
, oblock
, cblock
, old_ocell
);
1341 prealloc_free_structs(cache
, &structs
);
1344 /*----------------------------------------------------------------
1346 *--------------------------------------------------------------*/
1347 static void start_quiescing(struct cache
*cache
)
1349 unsigned long flags
;
1351 spin_lock_irqsave(&cache
->lock
, flags
);
1352 cache
->quiescing
= 1;
1353 spin_unlock_irqrestore(&cache
->lock
, flags
);
1356 static void stop_quiescing(struct cache
*cache
)
1358 unsigned long flags
;
1360 spin_lock_irqsave(&cache
->lock
, flags
);
1361 cache
->quiescing
= 0;
1362 spin_unlock_irqrestore(&cache
->lock
, flags
);
1365 static bool is_quiescing(struct cache
*cache
)
1368 unsigned long flags
;
1370 spin_lock_irqsave(&cache
->lock
, flags
);
1371 r
= cache
->quiescing
;
1372 spin_unlock_irqrestore(&cache
->lock
, flags
);
1377 static void wait_for_migrations(struct cache
*cache
)
1379 wait_event(cache
->migration_wait
, !atomic_read(&cache
->nr_migrations
));
1382 static void stop_worker(struct cache
*cache
)
1384 cancel_delayed_work(&cache
->waker
);
1385 flush_workqueue(cache
->wq
);
1388 static void requeue_deferred_io(struct cache
*cache
)
1391 struct bio_list bios
;
1393 bio_list_init(&bios
);
1394 bio_list_merge(&bios
, &cache
->deferred_bios
);
1395 bio_list_init(&cache
->deferred_bios
);
1397 while ((bio
= bio_list_pop(&bios
)))
1398 bio_endio(bio
, DM_ENDIO_REQUEUE
);
1401 static int more_work(struct cache
*cache
)
1403 if (is_quiescing(cache
))
1404 return !list_empty(&cache
->quiesced_migrations
) ||
1405 !list_empty(&cache
->completed_migrations
) ||
1406 !list_empty(&cache
->need_commit_migrations
);
1408 return !bio_list_empty(&cache
->deferred_bios
) ||
1409 !bio_list_empty(&cache
->deferred_flush_bios
) ||
1410 !bio_list_empty(&cache
->deferred_writethrough_bios
) ||
1411 !list_empty(&cache
->quiesced_migrations
) ||
1412 !list_empty(&cache
->completed_migrations
) ||
1413 !list_empty(&cache
->need_commit_migrations
);
1416 static void do_worker(struct work_struct
*ws
)
1418 struct cache
*cache
= container_of(ws
, struct cache
, worker
);
1421 if (!is_quiescing(cache
))
1422 process_deferred_bios(cache
);
1424 process_migrations(cache
, &cache
->quiesced_migrations
, issue_copy
);
1425 process_migrations(cache
, &cache
->completed_migrations
, complete_migration
);
1427 writeback_some_dirty_blocks(cache
);
1429 process_deferred_writethrough_bios(cache
);
1431 if (commit_if_needed(cache
)) {
1432 process_deferred_flush_bios(cache
, false);
1435 * FIXME: rollback metadata or just go into a
1436 * failure mode and error everything
1439 process_deferred_flush_bios(cache
, true);
1440 process_migrations(cache
, &cache
->need_commit_migrations
,
1441 migration_success_post_commit
);
1443 } while (more_work(cache
));
1447 * We want to commit periodically so that not too much
1448 * unwritten metadata builds up.
1450 static void do_waker(struct work_struct
*ws
)
1452 struct cache
*cache
= container_of(to_delayed_work(ws
), struct cache
, waker
);
1453 policy_tick(cache
->policy
);
1455 queue_delayed_work(cache
->wq
, &cache
->waker
, COMMIT_PERIOD
);
1458 /*----------------------------------------------------------------*/
1460 static int is_congested(struct dm_dev
*dev
, int bdi_bits
)
1462 struct request_queue
*q
= bdev_get_queue(dev
->bdev
);
1463 return bdi_congested(&q
->backing_dev_info
, bdi_bits
);
1466 static int cache_is_congested(struct dm_target_callbacks
*cb
, int bdi_bits
)
1468 struct cache
*cache
= container_of(cb
, struct cache
, callbacks
);
1470 return is_congested(cache
->origin_dev
, bdi_bits
) ||
1471 is_congested(cache
->cache_dev
, bdi_bits
);
1474 /*----------------------------------------------------------------
1476 *--------------------------------------------------------------*/
1479 * This function gets called on the error paths of the constructor, so we
1480 * have to cope with a partially initialised struct.
1482 static void destroy(struct cache
*cache
)
1486 if (cache
->next_migration
)
1487 mempool_free(cache
->next_migration
, cache
->migration_pool
);
1489 if (cache
->migration_pool
)
1490 mempool_destroy(cache
->migration_pool
);
1492 if (cache
->all_io_ds
)
1493 dm_deferred_set_destroy(cache
->all_io_ds
);
1496 dm_bio_prison_destroy(cache
->prison
);
1499 destroy_workqueue(cache
->wq
);
1501 if (cache
->dirty_bitset
)
1502 free_bitset(cache
->dirty_bitset
);
1504 if (cache
->discard_bitset
)
1505 free_bitset(cache
->discard_bitset
);
1508 dm_kcopyd_client_destroy(cache
->copier
);
1511 dm_cache_metadata_close(cache
->cmd
);
1513 if (cache
->metadata_dev
)
1514 dm_put_device(cache
->ti
, cache
->metadata_dev
);
1516 if (cache
->origin_dev
)
1517 dm_put_device(cache
->ti
, cache
->origin_dev
);
1519 if (cache
->cache_dev
)
1520 dm_put_device(cache
->ti
, cache
->cache_dev
);
1523 dm_cache_policy_destroy(cache
->policy
);
1525 for (i
= 0; i
< cache
->nr_ctr_args
; i
++)
1526 kfree(cache
->ctr_args
[i
]);
1527 kfree(cache
->ctr_args
);
1532 static void cache_dtr(struct dm_target
*ti
)
1534 struct cache
*cache
= ti
->private;
1539 static sector_t
get_dev_size(struct dm_dev
*dev
)
1541 return i_size_read(dev
->bdev
->bd_inode
) >> SECTOR_SHIFT
;
1544 /*----------------------------------------------------------------*/
1547 * Construct a cache device mapping.
1549 * cache <metadata dev> <cache dev> <origin dev> <block size>
1550 * <#feature args> [<feature arg>]*
1551 * <policy> <#policy args> [<policy arg>]*
1553 * metadata dev : fast device holding the persistent metadata
1554 * cache dev : fast device holding cached data blocks
1555 * origin dev : slow device holding original data blocks
1556 * block size : cache unit size in sectors
1558 * #feature args : number of feature arguments passed
1559 * feature args : writethrough. (The default is writeback.)
1561 * policy : the replacement policy to use
1562 * #policy args : an even number of policy arguments corresponding
1563 * to key/value pairs passed to the policy
1564 * policy args : key/value pairs passed to the policy
1565 * E.g. 'sequential_threshold 1024'
1566 * See cache-policies.txt for details.
1568 * Optional feature arguments are:
1569 * writethrough : write through caching that prohibits cache block
1570 * content from being different from origin block content.
1571 * Without this argument, the default behaviour is to write
1572 * back cache block contents later for performance reasons,
1573 * so they may differ from the corresponding origin blocks.
1576 struct dm_target
*ti
;
1578 struct dm_dev
*metadata_dev
;
1580 struct dm_dev
*cache_dev
;
1581 sector_t cache_sectors
;
1583 struct dm_dev
*origin_dev
;
1584 sector_t origin_sectors
;
1586 uint32_t block_size
;
1588 const char *policy_name
;
1590 const char **policy_argv
;
1592 struct cache_features features
;
1595 static void destroy_cache_args(struct cache_args
*ca
)
1597 if (ca
->metadata_dev
)
1598 dm_put_device(ca
->ti
, ca
->metadata_dev
);
1601 dm_put_device(ca
->ti
, ca
->cache_dev
);
1604 dm_put_device(ca
->ti
, ca
->origin_dev
);
1609 static bool at_least_one_arg(struct dm_arg_set
*as
, char **error
)
1612 *error
= "Insufficient args";
1619 static int parse_metadata_dev(struct cache_args
*ca
, struct dm_arg_set
*as
,
1623 sector_t metadata_dev_size
;
1624 char b
[BDEVNAME_SIZE
];
1626 if (!at_least_one_arg(as
, error
))
1629 r
= dm_get_device(ca
->ti
, dm_shift_arg(as
), FMODE_READ
| FMODE_WRITE
,
1632 *error
= "Error opening metadata device";
1636 metadata_dev_size
= get_dev_size(ca
->metadata_dev
);
1637 if (metadata_dev_size
> DM_CACHE_METADATA_MAX_SECTORS_WARNING
)
1638 DMWARN("Metadata device %s is larger than %u sectors: excess space will not be used.",
1639 bdevname(ca
->metadata_dev
->bdev
, b
), THIN_METADATA_MAX_SECTORS
);
1644 static int parse_cache_dev(struct cache_args
*ca
, struct dm_arg_set
*as
,
1649 if (!at_least_one_arg(as
, error
))
1652 r
= dm_get_device(ca
->ti
, dm_shift_arg(as
), FMODE_READ
| FMODE_WRITE
,
1655 *error
= "Error opening cache device";
1658 ca
->cache_sectors
= get_dev_size(ca
->cache_dev
);
1663 static int parse_origin_dev(struct cache_args
*ca
, struct dm_arg_set
*as
,
1668 if (!at_least_one_arg(as
, error
))
1671 r
= dm_get_device(ca
->ti
, dm_shift_arg(as
), FMODE_READ
| FMODE_WRITE
,
1674 *error
= "Error opening origin device";
1678 ca
->origin_sectors
= get_dev_size(ca
->origin_dev
);
1679 if (ca
->ti
->len
> ca
->origin_sectors
) {
1680 *error
= "Device size larger than cached device";
1687 static int parse_block_size(struct cache_args
*ca
, struct dm_arg_set
*as
,
1692 if (!at_least_one_arg(as
, error
))
1695 if (kstrtoul(dm_shift_arg(as
), 10, &tmp
) || !tmp
||
1696 tmp
< DATA_DEV_BLOCK_SIZE_MIN_SECTORS
||
1697 tmp
& (DATA_DEV_BLOCK_SIZE_MIN_SECTORS
- 1)) {
1698 *error
= "Invalid data block size";
1702 if (tmp
> ca
->cache_sectors
) {
1703 *error
= "Data block size is larger than the cache device";
1707 ca
->block_size
= tmp
;
1712 static void init_features(struct cache_features
*cf
)
1714 cf
->mode
= CM_WRITE
;
1715 cf
->write_through
= false;
1718 static int parse_features(struct cache_args
*ca
, struct dm_arg_set
*as
,
1721 static struct dm_arg _args
[] = {
1722 {0, 1, "Invalid number of cache feature arguments"},
1728 struct cache_features
*cf
= &ca
->features
;
1732 r
= dm_read_arg_group(_args
, as
, &argc
, error
);
1737 arg
= dm_shift_arg(as
);
1739 if (!strcasecmp(arg
, "writeback"))
1740 cf
->write_through
= false;
1742 else if (!strcasecmp(arg
, "writethrough"))
1743 cf
->write_through
= true;
1746 *error
= "Unrecognised cache feature requested";
1754 static int parse_policy(struct cache_args
*ca
, struct dm_arg_set
*as
,
1757 static struct dm_arg _args
[] = {
1758 {0, 1024, "Invalid number of policy arguments"},
1763 if (!at_least_one_arg(as
, error
))
1766 ca
->policy_name
= dm_shift_arg(as
);
1768 r
= dm_read_arg_group(_args
, as
, &ca
->policy_argc
, error
);
1772 ca
->policy_argv
= (const char **)as
->argv
;
1773 dm_consume_args(as
, ca
->policy_argc
);
1778 static int parse_cache_args(struct cache_args
*ca
, int argc
, char **argv
,
1782 struct dm_arg_set as
;
1787 r
= parse_metadata_dev(ca
, &as
, error
);
1791 r
= parse_cache_dev(ca
, &as
, error
);
1795 r
= parse_origin_dev(ca
, &as
, error
);
1799 r
= parse_block_size(ca
, &as
, error
);
1803 r
= parse_features(ca
, &as
, error
);
1807 r
= parse_policy(ca
, &as
, error
);
1814 /*----------------------------------------------------------------*/
1816 static struct kmem_cache
*migration_cache
;
1818 #define NOT_CORE_OPTION 1
1820 static int process_config_option(struct cache
*cache
, const char *key
, const char *value
)
1824 if (!strcasecmp(key
, "migration_threshold")) {
1825 if (kstrtoul(value
, 10, &tmp
))
1828 cache
->migration_threshold
= tmp
;
1832 return NOT_CORE_OPTION
;
1835 static int set_config_value(struct cache
*cache
, const char *key
, const char *value
)
1837 int r
= process_config_option(cache
, key
, value
);
1839 if (r
== NOT_CORE_OPTION
)
1840 r
= policy_set_config_value(cache
->policy
, key
, value
);
1843 DMWARN("bad config value for %s: %s", key
, value
);
1848 static int set_config_values(struct cache
*cache
, int argc
, const char **argv
)
1853 DMWARN("Odd number of policy arguments given but they should be <key> <value> pairs.");
1858 r
= set_config_value(cache
, argv
[0], argv
[1]);
1869 static int create_cache_policy(struct cache
*cache
, struct cache_args
*ca
,
1872 cache
->policy
= dm_cache_policy_create(ca
->policy_name
,
1874 cache
->origin_sectors
,
1875 cache
->sectors_per_block
);
1876 if (!cache
->policy
) {
1877 *error
= "Error creating cache's policy";
1885 * We want the discard block size to be a power of two, at least the size
1886 * of the cache block size, and have no more than 2^14 discard blocks
1887 * across the origin.
1889 #define MAX_DISCARD_BLOCKS (1 << 14)
1891 static bool too_many_discard_blocks(sector_t discard_block_size
,
1892 sector_t origin_size
)
1894 (void) sector_div(origin_size
, discard_block_size
);
1896 return origin_size
> MAX_DISCARD_BLOCKS
;
1899 static sector_t
calculate_discard_block_size(sector_t cache_block_size
,
1900 sector_t origin_size
)
1902 sector_t discard_block_size
;
1904 discard_block_size
= roundup_pow_of_two(cache_block_size
);
1907 while (too_many_discard_blocks(discard_block_size
, origin_size
))
1908 discard_block_size
*= 2;
1910 return discard_block_size
;
1913 #define DEFAULT_MIGRATION_THRESHOLD 2048
1915 static int cache_create(struct cache_args
*ca
, struct cache
**result
)
1918 char **error
= &ca
->ti
->error
;
1919 struct cache
*cache
;
1920 struct dm_target
*ti
= ca
->ti
;
1921 dm_block_t origin_blocks
;
1922 struct dm_cache_metadata
*cmd
;
1923 bool may_format
= ca
->features
.mode
== CM_WRITE
;
1925 cache
= kzalloc(sizeof(*cache
), GFP_KERNEL
);
1930 ti
->private = cache
;
1931 ti
->num_flush_bios
= 2;
1932 ti
->flush_supported
= true;
1934 ti
->num_discard_bios
= 1;
1935 ti
->discards_supported
= true;
1936 ti
->discard_zeroes_data_unsupported
= true;
1938 cache
->features
= ca
->features
;
1939 ti
->per_bio_data_size
= get_per_bio_data_size(cache
);
1941 cache
->callbacks
.congested_fn
= cache_is_congested
;
1942 dm_table_add_target_callbacks(ti
->table
, &cache
->callbacks
);
1944 cache
->metadata_dev
= ca
->metadata_dev
;
1945 cache
->origin_dev
= ca
->origin_dev
;
1946 cache
->cache_dev
= ca
->cache_dev
;
1948 ca
->metadata_dev
= ca
->origin_dev
= ca
->cache_dev
= NULL
;
1950 /* FIXME: factor out this whole section */
1951 origin_blocks
= cache
->origin_sectors
= ca
->origin_sectors
;
1952 origin_blocks
= block_div(origin_blocks
, ca
->block_size
);
1953 cache
->origin_blocks
= to_oblock(origin_blocks
);
1955 cache
->sectors_per_block
= ca
->block_size
;
1956 if (dm_set_target_max_io_len(ti
, cache
->sectors_per_block
)) {
1961 if (ca
->block_size
& (ca
->block_size
- 1)) {
1962 dm_block_t cache_size
= ca
->cache_sectors
;
1964 cache
->sectors_per_block_shift
= -1;
1965 cache_size
= block_div(cache_size
, ca
->block_size
);
1966 cache
->cache_size
= to_cblock(cache_size
);
1968 cache
->sectors_per_block_shift
= __ffs(ca
->block_size
);
1969 cache
->cache_size
= to_cblock(ca
->cache_sectors
>> cache
->sectors_per_block_shift
);
1972 r
= create_cache_policy(cache
, ca
, error
);
1976 cache
->policy_nr_args
= ca
->policy_argc
;
1977 cache
->migration_threshold
= DEFAULT_MIGRATION_THRESHOLD
;
1979 r
= set_config_values(cache
, ca
->policy_argc
, ca
->policy_argv
);
1981 *error
= "Error setting cache policy's config values";
1985 cmd
= dm_cache_metadata_open(cache
->metadata_dev
->bdev
,
1986 ca
->block_size
, may_format
,
1987 dm_cache_policy_get_hint_size(cache
->policy
));
1989 *error
= "Error creating metadata object";
1995 spin_lock_init(&cache
->lock
);
1996 bio_list_init(&cache
->deferred_bios
);
1997 bio_list_init(&cache
->deferred_flush_bios
);
1998 bio_list_init(&cache
->deferred_writethrough_bios
);
1999 INIT_LIST_HEAD(&cache
->quiesced_migrations
);
2000 INIT_LIST_HEAD(&cache
->completed_migrations
);
2001 INIT_LIST_HEAD(&cache
->need_commit_migrations
);
2002 atomic_set(&cache
->nr_migrations
, 0);
2003 init_waitqueue_head(&cache
->migration_wait
);
2006 cache
->nr_dirty
= 0;
2007 cache
->dirty_bitset
= alloc_bitset(from_cblock(cache
->cache_size
));
2008 if (!cache
->dirty_bitset
) {
2009 *error
= "could not allocate dirty bitset";
2012 clear_bitset(cache
->dirty_bitset
, from_cblock(cache
->cache_size
));
2014 cache
->discard_block_size
=
2015 calculate_discard_block_size(cache
->sectors_per_block
,
2016 cache
->origin_sectors
);
2017 cache
->discard_nr_blocks
= oblock_to_dblock(cache
, cache
->origin_blocks
);
2018 cache
->discard_bitset
= alloc_bitset(from_dblock(cache
->discard_nr_blocks
));
2019 if (!cache
->discard_bitset
) {
2020 *error
= "could not allocate discard bitset";
2023 clear_bitset(cache
->discard_bitset
, from_dblock(cache
->discard_nr_blocks
));
2025 cache
->copier
= dm_kcopyd_client_create(&dm_kcopyd_throttle
);
2026 if (IS_ERR(cache
->copier
)) {
2027 *error
= "could not create kcopyd client";
2028 r
= PTR_ERR(cache
->copier
);
2032 cache
->wq
= alloc_ordered_workqueue("dm-" DM_MSG_PREFIX
, WQ_MEM_RECLAIM
);
2034 *error
= "could not create workqueue for metadata object";
2037 INIT_WORK(&cache
->worker
, do_worker
);
2038 INIT_DELAYED_WORK(&cache
->waker
, do_waker
);
2039 cache
->last_commit_jiffies
= jiffies
;
2041 cache
->prison
= dm_bio_prison_create(PRISON_CELLS
);
2042 if (!cache
->prison
) {
2043 *error
= "could not create bio prison";
2047 cache
->all_io_ds
= dm_deferred_set_create();
2048 if (!cache
->all_io_ds
) {
2049 *error
= "could not create all_io deferred set";
2053 cache
->migration_pool
= mempool_create_slab_pool(MIGRATION_POOL_SIZE
,
2055 if (!cache
->migration_pool
) {
2056 *error
= "Error creating cache's migration mempool";
2060 cache
->next_migration
= NULL
;
2062 cache
->need_tick_bio
= true;
2063 cache
->sized
= false;
2064 cache
->quiescing
= false;
2065 cache
->commit_requested
= false;
2066 cache
->loaded_mappings
= false;
2067 cache
->loaded_discards
= false;
2071 atomic_set(&cache
->stats
.demotion
, 0);
2072 atomic_set(&cache
->stats
.promotion
, 0);
2073 atomic_set(&cache
->stats
.copies_avoided
, 0);
2074 atomic_set(&cache
->stats
.cache_cell_clash
, 0);
2075 atomic_set(&cache
->stats
.commit_count
, 0);
2076 atomic_set(&cache
->stats
.discard_count
, 0);
2086 static int copy_ctr_args(struct cache
*cache
, int argc
, const char **argv
)
2091 copy
= kcalloc(argc
, sizeof(*copy
), GFP_KERNEL
);
2094 for (i
= 0; i
< argc
; i
++) {
2095 copy
[i
] = kstrdup(argv
[i
], GFP_KERNEL
);
2104 cache
->nr_ctr_args
= argc
;
2105 cache
->ctr_args
= copy
;
2110 static int cache_ctr(struct dm_target
*ti
, unsigned argc
, char **argv
)
2113 struct cache_args
*ca
;
2114 struct cache
*cache
= NULL
;
2116 ca
= kzalloc(sizeof(*ca
), GFP_KERNEL
);
2118 ti
->error
= "Error allocating memory for cache";
2123 r
= parse_cache_args(ca
, argc
, argv
, &ti
->error
);
2127 r
= cache_create(ca
, &cache
);
2131 r
= copy_ctr_args(cache
, argc
- 3, (const char **)argv
+ 3);
2137 ti
->private = cache
;
2140 destroy_cache_args(ca
);
2144 static int cache_map(struct dm_target
*ti
, struct bio
*bio
)
2146 struct cache
*cache
= ti
->private;
2149 dm_oblock_t block
= get_bio_block(cache
, bio
);
2150 size_t pb_data_size
= get_per_bio_data_size(cache
);
2151 bool can_migrate
= false;
2152 bool discarded_block
;
2153 struct dm_bio_prison_cell
*cell
;
2154 struct policy_result lookup_result
;
2155 struct per_bio_data
*pb
;
2157 if (from_oblock(block
) > from_oblock(cache
->origin_blocks
)) {
2159 * This can only occur if the io goes to a partial block at
2160 * the end of the origin device. We don't cache these.
2161 * Just remap to the origin and carry on.
2163 remap_to_origin_clear_discard(cache
, bio
, block
);
2164 return DM_MAPIO_REMAPPED
;
2167 pb
= init_per_bio_data(bio
, pb_data_size
);
2169 if (bio
->bi_rw
& (REQ_FLUSH
| REQ_FUA
| REQ_DISCARD
)) {
2170 defer_bio(cache
, bio
);
2171 return DM_MAPIO_SUBMITTED
;
2175 * Check to see if that block is currently migrating.
2177 cell
= alloc_prison_cell(cache
);
2179 defer_bio(cache
, bio
);
2180 return DM_MAPIO_SUBMITTED
;
2183 r
= bio_detain(cache
, block
, bio
, cell
,
2184 (cell_free_fn
) free_prison_cell
,
2188 defer_bio(cache
, bio
);
2190 return DM_MAPIO_SUBMITTED
;
2193 discarded_block
= is_discarded_oblock(cache
, block
);
2195 r
= policy_map(cache
->policy
, block
, false, can_migrate
, discarded_block
,
2196 bio
, &lookup_result
);
2197 if (r
== -EWOULDBLOCK
) {
2198 cell_defer(cache
, cell
, true);
2199 return DM_MAPIO_SUBMITTED
;
2202 DMERR_LIMIT("Unexpected return from cache replacement policy: %d", r
);
2204 return DM_MAPIO_SUBMITTED
;
2207 switch (lookup_result
.op
) {
2209 inc_hit_counter(cache
, bio
);
2210 pb
->all_io_entry
= dm_deferred_entry_inc(cache
->all_io_ds
);
2212 if (is_writethrough_io(cache
, bio
, lookup_result
.cblock
))
2213 remap_to_origin_then_cache(cache
, bio
, block
, lookup_result
.cblock
);
2215 remap_to_cache_dirty(cache
, bio
, block
, lookup_result
.cblock
);
2217 cell_defer(cache
, cell
, false);
2221 inc_miss_counter(cache
, bio
);
2222 pb
->all_io_entry
= dm_deferred_entry_inc(cache
->all_io_ds
);
2224 if (pb
->req_nr
!= 0) {
2226 * This is a duplicate writethrough io that is no
2227 * longer needed because the block has been demoted.
2230 cell_defer(cache
, cell
, false);
2231 return DM_MAPIO_SUBMITTED
;
2233 remap_to_origin_clear_discard(cache
, bio
, block
);
2234 cell_defer(cache
, cell
, false);
2239 DMERR_LIMIT("%s: erroring bio: unknown policy op: %u", __func__
,
2240 (unsigned) lookup_result
.op
);
2242 return DM_MAPIO_SUBMITTED
;
2245 return DM_MAPIO_REMAPPED
;
2248 static int cache_end_io(struct dm_target
*ti
, struct bio
*bio
, int error
)
2250 struct cache
*cache
= ti
->private;
2251 unsigned long flags
;
2252 size_t pb_data_size
= get_per_bio_data_size(cache
);
2253 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
2256 policy_tick(cache
->policy
);
2258 spin_lock_irqsave(&cache
->lock
, flags
);
2259 cache
->need_tick_bio
= true;
2260 spin_unlock_irqrestore(&cache
->lock
, flags
);
2263 check_for_quiesced_migrations(cache
, pb
);
2268 static int write_dirty_bitset(struct cache
*cache
)
2272 for (i
= 0; i
< from_cblock(cache
->cache_size
); i
++) {
2273 r
= dm_cache_set_dirty(cache
->cmd
, to_cblock(i
),
2274 is_dirty(cache
, to_cblock(i
)));
2282 static int write_discard_bitset(struct cache
*cache
)
2286 r
= dm_cache_discard_bitset_resize(cache
->cmd
, cache
->discard_block_size
,
2287 cache
->discard_nr_blocks
);
2289 DMERR("could not resize on-disk discard bitset");
2293 for (i
= 0; i
< from_dblock(cache
->discard_nr_blocks
); i
++) {
2294 r
= dm_cache_set_discard(cache
->cmd
, to_dblock(i
),
2295 is_discarded(cache
, to_dblock(i
)));
2303 static int save_hint(void *context
, dm_cblock_t cblock
, dm_oblock_t oblock
,
2306 struct cache
*cache
= context
;
2307 return dm_cache_save_hint(cache
->cmd
, cblock
, hint
);
2310 static int write_hints(struct cache
*cache
)
2314 r
= dm_cache_begin_hints(cache
->cmd
, cache
->policy
);
2316 DMERR("dm_cache_begin_hints failed");
2320 r
= policy_walk_mappings(cache
->policy
, save_hint
, cache
);
2322 DMERR("policy_walk_mappings failed");
2328 * returns true on success
2330 static bool sync_metadata(struct cache
*cache
)
2334 r1
= write_dirty_bitset(cache
);
2336 DMERR("could not write dirty bitset");
2338 r2
= write_discard_bitset(cache
);
2340 DMERR("could not write discard bitset");
2344 r3
= write_hints(cache
);
2346 DMERR("could not write hints");
2349 * If writing the above metadata failed, we still commit, but don't
2350 * set the clean shutdown flag. This will effectively force every
2351 * dirty bit to be set on reload.
2353 r4
= dm_cache_commit(cache
->cmd
, !r1
&& !r2
&& !r3
);
2355 DMERR("could not write cache metadata. Data loss may occur.");
2357 return !r1
&& !r2
&& !r3
&& !r4
;
2360 static void cache_postsuspend(struct dm_target
*ti
)
2362 struct cache
*cache
= ti
->private;
2364 start_quiescing(cache
);
2365 wait_for_migrations(cache
);
2367 requeue_deferred_io(cache
);
2368 stop_quiescing(cache
);
2370 (void) sync_metadata(cache
);
2373 static int load_mapping(void *context
, dm_oblock_t oblock
, dm_cblock_t cblock
,
2374 bool dirty
, uint32_t hint
, bool hint_valid
)
2377 struct cache
*cache
= context
;
2379 r
= policy_load_mapping(cache
->policy
, oblock
, cblock
, hint
, hint_valid
);
2384 set_dirty(cache
, oblock
, cblock
);
2386 clear_dirty(cache
, oblock
, cblock
);
2391 static int load_discard(void *context
, sector_t discard_block_size
,
2392 dm_dblock_t dblock
, bool discard
)
2394 struct cache
*cache
= context
;
2396 /* FIXME: handle mis-matched block size */
2399 set_discard(cache
, dblock
);
2401 clear_discard(cache
, dblock
);
2406 static int cache_preresume(struct dm_target
*ti
)
2409 struct cache
*cache
= ti
->private;
2410 sector_t actual_cache_size
= get_dev_size(cache
->cache_dev
);
2411 (void) sector_div(actual_cache_size
, cache
->sectors_per_block
);
2414 * Check to see if the cache has resized.
2416 if (from_cblock(cache
->cache_size
) != actual_cache_size
|| !cache
->sized
) {
2417 cache
->cache_size
= to_cblock(actual_cache_size
);
2419 r
= dm_cache_resize(cache
->cmd
, cache
->cache_size
);
2421 DMERR("could not resize cache metadata");
2425 cache
->sized
= true;
2428 if (!cache
->loaded_mappings
) {
2429 r
= dm_cache_load_mappings(cache
->cmd
, cache
->policy
,
2430 load_mapping
, cache
);
2432 DMERR("could not load cache mappings");
2436 cache
->loaded_mappings
= true;
2439 if (!cache
->loaded_discards
) {
2440 r
= dm_cache_load_discards(cache
->cmd
, load_discard
, cache
);
2442 DMERR("could not load origin discards");
2446 cache
->loaded_discards
= true;
2452 static void cache_resume(struct dm_target
*ti
)
2454 struct cache
*cache
= ti
->private;
2456 cache
->need_tick_bio
= true;
2457 do_waker(&cache
->waker
.work
);
2463 * <#used metadata blocks>/<#total metadata blocks>
2464 * <#read hits> <#read misses> <#write hits> <#write misses>
2465 * <#demotions> <#promotions> <#blocks in cache> <#dirty>
2466 * <#features> <features>*
2467 * <#core args> <core args>
2468 * <#policy args> <policy args>*
2470 static void cache_status(struct dm_target
*ti
, status_type_t type
,
2471 unsigned status_flags
, char *result
, unsigned maxlen
)
2476 dm_block_t nr_free_blocks_metadata
= 0;
2477 dm_block_t nr_blocks_metadata
= 0;
2478 char buf
[BDEVNAME_SIZE
];
2479 struct cache
*cache
= ti
->private;
2480 dm_cblock_t residency
;
2483 case STATUSTYPE_INFO
:
2484 /* Commit to ensure statistics aren't out-of-date */
2485 if (!(status_flags
& DM_STATUS_NOFLUSH_FLAG
) && !dm_suspended(ti
)) {
2486 r
= dm_cache_commit(cache
->cmd
, false);
2488 DMERR("could not commit metadata for accurate status");
2491 r
= dm_cache_get_free_metadata_block_count(cache
->cmd
,
2492 &nr_free_blocks_metadata
);
2494 DMERR("could not get metadata free block count");
2498 r
= dm_cache_get_metadata_dev_size(cache
->cmd
, &nr_blocks_metadata
);
2500 DMERR("could not get metadata device size");
2504 residency
= policy_residency(cache
->policy
);
2506 DMEMIT("%llu/%llu %u %u %u %u %u %u %llu %u ",
2507 (unsigned long long)(nr_blocks_metadata
- nr_free_blocks_metadata
),
2508 (unsigned long long)nr_blocks_metadata
,
2509 (unsigned) atomic_read(&cache
->stats
.read_hit
),
2510 (unsigned) atomic_read(&cache
->stats
.read_miss
),
2511 (unsigned) atomic_read(&cache
->stats
.write_hit
),
2512 (unsigned) atomic_read(&cache
->stats
.write_miss
),
2513 (unsigned) atomic_read(&cache
->stats
.demotion
),
2514 (unsigned) atomic_read(&cache
->stats
.promotion
),
2515 (unsigned long long) from_cblock(residency
),
2518 if (cache
->features
.write_through
)
2519 DMEMIT("1 writethrough ");
2523 DMEMIT("2 migration_threshold %llu ", (unsigned long long) cache
->migration_threshold
);
2525 r
= policy_emit_config_values(cache
->policy
, result
+ sz
, maxlen
- sz
);
2527 DMERR("policy_emit_config_values returned %d", r
);
2532 case STATUSTYPE_TABLE
:
2533 format_dev_t(buf
, cache
->metadata_dev
->bdev
->bd_dev
);
2535 format_dev_t(buf
, cache
->cache_dev
->bdev
->bd_dev
);
2537 format_dev_t(buf
, cache
->origin_dev
->bdev
->bd_dev
);
2540 for (i
= 0; i
< cache
->nr_ctr_args
- 1; i
++)
2541 DMEMIT(" %s", cache
->ctr_args
[i
]);
2542 if (cache
->nr_ctr_args
)
2543 DMEMIT(" %s", cache
->ctr_args
[cache
->nr_ctr_args
- 1]);
2553 * Supports <key> <value>.
2555 * The key migration_threshold is supported by the cache target core.
2557 static int cache_message(struct dm_target
*ti
, unsigned argc
, char **argv
)
2559 struct cache
*cache
= ti
->private;
2564 return set_config_value(cache
, argv
[0], argv
[1]);
2567 static int cache_iterate_devices(struct dm_target
*ti
,
2568 iterate_devices_callout_fn fn
, void *data
)
2571 struct cache
*cache
= ti
->private;
2573 r
= fn(ti
, cache
->cache_dev
, 0, get_dev_size(cache
->cache_dev
), data
);
2575 r
= fn(ti
, cache
->origin_dev
, 0, ti
->len
, data
);
2581 * We assume I/O is going to the origin (which is the volume
2582 * more likely to have restrictions e.g. by being striped).
2583 * (Looking up the exact location of the data would be expensive
2584 * and could always be out of date by the time the bio is submitted.)
2586 static int cache_bvec_merge(struct dm_target
*ti
,
2587 struct bvec_merge_data
*bvm
,
2588 struct bio_vec
*biovec
, int max_size
)
2590 struct cache
*cache
= ti
->private;
2591 struct request_queue
*q
= bdev_get_queue(cache
->origin_dev
->bdev
);
2593 if (!q
->merge_bvec_fn
)
2596 bvm
->bi_bdev
= cache
->origin_dev
->bdev
;
2597 return min(max_size
, q
->merge_bvec_fn(q
, bvm
, biovec
));
2600 static void set_discard_limits(struct cache
*cache
, struct queue_limits
*limits
)
2603 * FIXME: these limits may be incompatible with the cache device
2605 limits
->max_discard_sectors
= cache
->discard_block_size
* 1024;
2606 limits
->discard_granularity
= cache
->discard_block_size
<< SECTOR_SHIFT
;
2609 static void cache_io_hints(struct dm_target
*ti
, struct queue_limits
*limits
)
2611 struct cache
*cache
= ti
->private;
2613 blk_limits_io_min(limits
, 0);
2614 blk_limits_io_opt(limits
, cache
->sectors_per_block
<< SECTOR_SHIFT
);
2615 set_discard_limits(cache
, limits
);
2618 /*----------------------------------------------------------------*/
2620 static struct target_type cache_target
= {
2622 .version
= {1, 1, 1},
2623 .module
= THIS_MODULE
,
2627 .end_io
= cache_end_io
,
2628 .postsuspend
= cache_postsuspend
,
2629 .preresume
= cache_preresume
,
2630 .resume
= cache_resume
,
2631 .status
= cache_status
,
2632 .message
= cache_message
,
2633 .iterate_devices
= cache_iterate_devices
,
2634 .merge
= cache_bvec_merge
,
2635 .io_hints
= cache_io_hints
,
2638 static int __init
dm_cache_init(void)
2642 r
= dm_register_target(&cache_target
);
2644 DMERR("cache target registration failed: %d", r
);
2648 migration_cache
= KMEM_CACHE(dm_cache_migration
, 0);
2649 if (!migration_cache
) {
2650 dm_unregister_target(&cache_target
);
2657 static void __exit
dm_cache_exit(void)
2659 dm_unregister_target(&cache_target
);
2660 kmem_cache_destroy(migration_cache
);
2663 module_init(dm_cache_init
);
2664 module_exit(dm_cache_exit
);
2666 MODULE_DESCRIPTION(DM_NAME
" cache target");
2667 MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
2668 MODULE_LICENSE("GPL");