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 static dm_block_t
block_div(dm_block_t b
, uint32_t n
)
435 static dm_dblock_t
oblock_to_dblock(struct cache
*cache
, dm_oblock_t oblock
)
437 uint32_t discard_blocks
= cache
->discard_block_size
;
438 dm_block_t b
= from_oblock(oblock
);
440 if (!block_size_is_power_of_two(cache
))
441 discard_blocks
= discard_blocks
/ cache
->sectors_per_block
;
443 discard_blocks
>>= cache
->sectors_per_block_shift
;
445 b
= block_div(b
, discard_blocks
);
450 static void set_discard(struct cache
*cache
, dm_dblock_t b
)
454 atomic_inc(&cache
->stats
.discard_count
);
456 spin_lock_irqsave(&cache
->lock
, flags
);
457 set_bit(from_dblock(b
), cache
->discard_bitset
);
458 spin_unlock_irqrestore(&cache
->lock
, flags
);
461 static void clear_discard(struct cache
*cache
, dm_dblock_t b
)
465 spin_lock_irqsave(&cache
->lock
, flags
);
466 clear_bit(from_dblock(b
), cache
->discard_bitset
);
467 spin_unlock_irqrestore(&cache
->lock
, flags
);
470 static bool is_discarded(struct cache
*cache
, dm_dblock_t b
)
475 spin_lock_irqsave(&cache
->lock
, flags
);
476 r
= test_bit(from_dblock(b
), cache
->discard_bitset
);
477 spin_unlock_irqrestore(&cache
->lock
, flags
);
482 static bool is_discarded_oblock(struct cache
*cache
, dm_oblock_t b
)
487 spin_lock_irqsave(&cache
->lock
, flags
);
488 r
= test_bit(from_dblock(oblock_to_dblock(cache
, b
)),
489 cache
->discard_bitset
);
490 spin_unlock_irqrestore(&cache
->lock
, flags
);
495 /*----------------------------------------------------------------*/
497 static void load_stats(struct cache
*cache
)
499 struct dm_cache_statistics stats
;
501 dm_cache_metadata_get_stats(cache
->cmd
, &stats
);
502 atomic_set(&cache
->stats
.read_hit
, stats
.read_hits
);
503 atomic_set(&cache
->stats
.read_miss
, stats
.read_misses
);
504 atomic_set(&cache
->stats
.write_hit
, stats
.write_hits
);
505 atomic_set(&cache
->stats
.write_miss
, stats
.write_misses
);
508 static void save_stats(struct cache
*cache
)
510 struct dm_cache_statistics stats
;
512 stats
.read_hits
= atomic_read(&cache
->stats
.read_hit
);
513 stats
.read_misses
= atomic_read(&cache
->stats
.read_miss
);
514 stats
.write_hits
= atomic_read(&cache
->stats
.write_hit
);
515 stats
.write_misses
= atomic_read(&cache
->stats
.write_miss
);
517 dm_cache_metadata_set_stats(cache
->cmd
, &stats
);
520 /*----------------------------------------------------------------
522 *--------------------------------------------------------------*/
525 * If using writeback, leave out struct per_bio_data's writethrough fields.
527 #define PB_DATA_SIZE_WB (offsetof(struct per_bio_data, cache))
528 #define PB_DATA_SIZE_WT (sizeof(struct per_bio_data))
530 static size_t get_per_bio_data_size(struct cache
*cache
)
532 return cache
->features
.write_through
? PB_DATA_SIZE_WT
: PB_DATA_SIZE_WB
;
535 static struct per_bio_data
*get_per_bio_data(struct bio
*bio
, size_t data_size
)
537 struct per_bio_data
*pb
= dm_per_bio_data(bio
, data_size
);
542 static struct per_bio_data
*init_per_bio_data(struct bio
*bio
, size_t data_size
)
544 struct per_bio_data
*pb
= get_per_bio_data(bio
, data_size
);
547 pb
->req_nr
= dm_bio_get_target_bio_nr(bio
);
548 pb
->all_io_entry
= NULL
;
553 /*----------------------------------------------------------------
555 *--------------------------------------------------------------*/
556 static void remap_to_origin(struct cache
*cache
, struct bio
*bio
)
558 bio
->bi_bdev
= cache
->origin_dev
->bdev
;
561 static void remap_to_cache(struct cache
*cache
, struct bio
*bio
,
564 sector_t bi_sector
= bio
->bi_sector
;
566 bio
->bi_bdev
= cache
->cache_dev
->bdev
;
567 if (!block_size_is_power_of_two(cache
))
568 bio
->bi_sector
= (from_cblock(cblock
) * cache
->sectors_per_block
) +
569 sector_div(bi_sector
, cache
->sectors_per_block
);
571 bio
->bi_sector
= (from_cblock(cblock
) << cache
->sectors_per_block_shift
) |
572 (bi_sector
& (cache
->sectors_per_block
- 1));
575 static void check_if_tick_bio_needed(struct cache
*cache
, struct bio
*bio
)
578 size_t pb_data_size
= get_per_bio_data_size(cache
);
579 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
581 spin_lock_irqsave(&cache
->lock
, flags
);
582 if (cache
->need_tick_bio
&&
583 !(bio
->bi_rw
& (REQ_FUA
| REQ_FLUSH
| REQ_DISCARD
))) {
585 cache
->need_tick_bio
= false;
587 spin_unlock_irqrestore(&cache
->lock
, flags
);
590 static void remap_to_origin_clear_discard(struct cache
*cache
, struct bio
*bio
,
593 check_if_tick_bio_needed(cache
, bio
);
594 remap_to_origin(cache
, bio
);
595 if (bio_data_dir(bio
) == WRITE
)
596 clear_discard(cache
, oblock_to_dblock(cache
, oblock
));
599 static void remap_to_cache_dirty(struct cache
*cache
, struct bio
*bio
,
600 dm_oblock_t oblock
, dm_cblock_t cblock
)
602 remap_to_cache(cache
, bio
, cblock
);
603 if (bio_data_dir(bio
) == WRITE
) {
604 set_dirty(cache
, oblock
, cblock
);
605 clear_discard(cache
, oblock_to_dblock(cache
, oblock
));
609 static dm_oblock_t
get_bio_block(struct cache
*cache
, struct bio
*bio
)
611 sector_t block_nr
= bio
->bi_sector
;
613 if (!block_size_is_power_of_two(cache
))
614 (void) sector_div(block_nr
, cache
->sectors_per_block
);
616 block_nr
>>= cache
->sectors_per_block_shift
;
618 return to_oblock(block_nr
);
621 static int bio_triggers_commit(struct cache
*cache
, struct bio
*bio
)
623 return bio
->bi_rw
& (REQ_FLUSH
| REQ_FUA
);
626 static void issue(struct cache
*cache
, struct bio
*bio
)
630 if (!bio_triggers_commit(cache
, bio
)) {
631 generic_make_request(bio
);
636 * Batch together any bios that trigger commits and then issue a
637 * single commit for them in do_worker().
639 spin_lock_irqsave(&cache
->lock
, flags
);
640 cache
->commit_requested
= true;
641 bio_list_add(&cache
->deferred_flush_bios
, bio
);
642 spin_unlock_irqrestore(&cache
->lock
, flags
);
645 static void defer_writethrough_bio(struct cache
*cache
, struct bio
*bio
)
649 spin_lock_irqsave(&cache
->lock
, flags
);
650 bio_list_add(&cache
->deferred_writethrough_bios
, bio
);
651 spin_unlock_irqrestore(&cache
->lock
, flags
);
656 static void writethrough_endio(struct bio
*bio
, int err
)
658 struct per_bio_data
*pb
= get_per_bio_data(bio
, PB_DATA_SIZE_WT
);
659 bio
->bi_end_io
= pb
->saved_bi_end_io
;
666 dm_bio_restore(&pb
->bio_details
, bio
);
667 remap_to_cache(pb
->cache
, bio
, pb
->cblock
);
670 * We can't issue this bio directly, since we're in interrupt
671 * context. So it gets put on a bio list for processing by the
674 defer_writethrough_bio(pb
->cache
, bio
);
678 * When running in writethrough mode we need to send writes to clean blocks
679 * to both the cache and origin devices. In future we'd like to clone the
680 * bio and send them in parallel, but for now we're doing them in
681 * series as this is easier.
683 static void remap_to_origin_then_cache(struct cache
*cache
, struct bio
*bio
,
684 dm_oblock_t oblock
, dm_cblock_t cblock
)
686 struct per_bio_data
*pb
= get_per_bio_data(bio
, PB_DATA_SIZE_WT
);
690 pb
->saved_bi_end_io
= bio
->bi_end_io
;
691 dm_bio_record(&pb
->bio_details
, bio
);
692 bio
->bi_end_io
= writethrough_endio
;
694 remap_to_origin_clear_discard(pb
->cache
, bio
, oblock
);
697 /*----------------------------------------------------------------
698 * Migration processing
700 * Migration covers moving data from the origin device to the cache, or
702 *--------------------------------------------------------------*/
703 static void free_migration(struct dm_cache_migration
*mg
)
705 mempool_free(mg
, mg
->cache
->migration_pool
);
708 static void inc_nr_migrations(struct cache
*cache
)
710 atomic_inc(&cache
->nr_migrations
);
713 static void dec_nr_migrations(struct cache
*cache
)
715 atomic_dec(&cache
->nr_migrations
);
718 * Wake the worker in case we're suspending the target.
720 wake_up(&cache
->migration_wait
);
723 static void __cell_defer(struct cache
*cache
, struct dm_bio_prison_cell
*cell
,
726 (holder
? dm_cell_release
: dm_cell_release_no_holder
)
727 (cache
->prison
, cell
, &cache
->deferred_bios
);
728 free_prison_cell(cache
, cell
);
731 static void cell_defer(struct cache
*cache
, struct dm_bio_prison_cell
*cell
,
736 spin_lock_irqsave(&cache
->lock
, flags
);
737 __cell_defer(cache
, cell
, holder
);
738 spin_unlock_irqrestore(&cache
->lock
, flags
);
743 static void cleanup_migration(struct dm_cache_migration
*mg
)
745 dec_nr_migrations(mg
->cache
);
749 static void migration_failure(struct dm_cache_migration
*mg
)
751 struct cache
*cache
= mg
->cache
;
754 DMWARN_LIMIT("writeback failed; couldn't copy block");
755 set_dirty(cache
, mg
->old_oblock
, mg
->cblock
);
756 cell_defer(cache
, mg
->old_ocell
, false);
758 } else if (mg
->demote
) {
759 DMWARN_LIMIT("demotion failed; couldn't copy block");
760 policy_force_mapping(cache
->policy
, mg
->new_oblock
, mg
->old_oblock
);
762 cell_defer(cache
, mg
->old_ocell
, mg
->promote
? 0 : 1);
764 cell_defer(cache
, mg
->new_ocell
, 1);
766 DMWARN_LIMIT("promotion failed; couldn't copy block");
767 policy_remove_mapping(cache
->policy
, mg
->new_oblock
);
768 cell_defer(cache
, mg
->new_ocell
, 1);
771 cleanup_migration(mg
);
774 static void migration_success_pre_commit(struct dm_cache_migration
*mg
)
777 struct cache
*cache
= mg
->cache
;
780 cell_defer(cache
, mg
->old_ocell
, false);
781 clear_dirty(cache
, mg
->old_oblock
, mg
->cblock
);
782 cleanup_migration(mg
);
785 } else if (mg
->demote
) {
786 if (dm_cache_remove_mapping(cache
->cmd
, mg
->cblock
)) {
787 DMWARN_LIMIT("demotion failed; couldn't update on disk metadata");
788 policy_force_mapping(cache
->policy
, mg
->new_oblock
,
791 cell_defer(cache
, mg
->new_ocell
, true);
792 cleanup_migration(mg
);
796 if (dm_cache_insert_mapping(cache
->cmd
, mg
->cblock
, mg
->new_oblock
)) {
797 DMWARN_LIMIT("promotion failed; couldn't update on disk metadata");
798 policy_remove_mapping(cache
->policy
, mg
->new_oblock
);
799 cleanup_migration(mg
);
804 spin_lock_irqsave(&cache
->lock
, flags
);
805 list_add_tail(&mg
->list
, &cache
->need_commit_migrations
);
806 cache
->commit_requested
= true;
807 spin_unlock_irqrestore(&cache
->lock
, flags
);
810 static void migration_success_post_commit(struct dm_cache_migration
*mg
)
813 struct cache
*cache
= mg
->cache
;
816 DMWARN("writeback unexpectedly triggered commit");
819 } else if (mg
->demote
) {
820 cell_defer(cache
, mg
->old_ocell
, mg
->promote
? 0 : 1);
825 spin_lock_irqsave(&cache
->lock
, flags
);
826 list_add_tail(&mg
->list
, &cache
->quiesced_migrations
);
827 spin_unlock_irqrestore(&cache
->lock
, flags
);
830 cleanup_migration(mg
);
833 cell_defer(cache
, mg
->new_ocell
, true);
834 clear_dirty(cache
, mg
->new_oblock
, mg
->cblock
);
835 cleanup_migration(mg
);
839 static void copy_complete(int read_err
, unsigned long write_err
, void *context
)
842 struct dm_cache_migration
*mg
= (struct dm_cache_migration
*) context
;
843 struct cache
*cache
= mg
->cache
;
845 if (read_err
|| write_err
)
848 spin_lock_irqsave(&cache
->lock
, flags
);
849 list_add_tail(&mg
->list
, &cache
->completed_migrations
);
850 spin_unlock_irqrestore(&cache
->lock
, flags
);
855 static void issue_copy_real(struct dm_cache_migration
*mg
)
858 struct dm_io_region o_region
, c_region
;
859 struct cache
*cache
= mg
->cache
;
861 o_region
.bdev
= cache
->origin_dev
->bdev
;
862 o_region
.count
= cache
->sectors_per_block
;
864 c_region
.bdev
= cache
->cache_dev
->bdev
;
865 c_region
.sector
= from_cblock(mg
->cblock
) * cache
->sectors_per_block
;
866 c_region
.count
= cache
->sectors_per_block
;
868 if (mg
->writeback
|| mg
->demote
) {
870 o_region
.sector
= from_oblock(mg
->old_oblock
) * cache
->sectors_per_block
;
871 r
= dm_kcopyd_copy(cache
->copier
, &c_region
, 1, &o_region
, 0, copy_complete
, mg
);
874 o_region
.sector
= from_oblock(mg
->new_oblock
) * cache
->sectors_per_block
;
875 r
= dm_kcopyd_copy(cache
->copier
, &o_region
, 1, &c_region
, 0, copy_complete
, mg
);
879 migration_failure(mg
);
882 static void avoid_copy(struct dm_cache_migration
*mg
)
884 atomic_inc(&mg
->cache
->stats
.copies_avoided
);
885 migration_success_pre_commit(mg
);
888 static void issue_copy(struct dm_cache_migration
*mg
)
891 struct cache
*cache
= mg
->cache
;
893 if (mg
->writeback
|| mg
->demote
)
894 avoid
= !is_dirty(cache
, mg
->cblock
) ||
895 is_discarded_oblock(cache
, mg
->old_oblock
);
897 avoid
= is_discarded_oblock(cache
, mg
->new_oblock
);
899 avoid
? avoid_copy(mg
) : issue_copy_real(mg
);
902 static void complete_migration(struct dm_cache_migration
*mg
)
905 migration_failure(mg
);
907 migration_success_pre_commit(mg
);
910 static void process_migrations(struct cache
*cache
, struct list_head
*head
,
911 void (*fn
)(struct dm_cache_migration
*))
914 struct list_head list
;
915 struct dm_cache_migration
*mg
, *tmp
;
917 INIT_LIST_HEAD(&list
);
918 spin_lock_irqsave(&cache
->lock
, flags
);
919 list_splice_init(head
, &list
);
920 spin_unlock_irqrestore(&cache
->lock
, flags
);
922 list_for_each_entry_safe(mg
, tmp
, &list
, list
)
926 static void __queue_quiesced_migration(struct dm_cache_migration
*mg
)
928 list_add_tail(&mg
->list
, &mg
->cache
->quiesced_migrations
);
931 static void queue_quiesced_migration(struct dm_cache_migration
*mg
)
934 struct cache
*cache
= mg
->cache
;
936 spin_lock_irqsave(&cache
->lock
, flags
);
937 __queue_quiesced_migration(mg
);
938 spin_unlock_irqrestore(&cache
->lock
, flags
);
943 static void queue_quiesced_migrations(struct cache
*cache
, struct list_head
*work
)
946 struct dm_cache_migration
*mg
, *tmp
;
948 spin_lock_irqsave(&cache
->lock
, flags
);
949 list_for_each_entry_safe(mg
, tmp
, work
, list
)
950 __queue_quiesced_migration(mg
);
951 spin_unlock_irqrestore(&cache
->lock
, flags
);
956 static void check_for_quiesced_migrations(struct cache
*cache
,
957 struct per_bio_data
*pb
)
959 struct list_head work
;
961 if (!pb
->all_io_entry
)
964 INIT_LIST_HEAD(&work
);
965 if (pb
->all_io_entry
)
966 dm_deferred_entry_dec(pb
->all_io_entry
, &work
);
968 if (!list_empty(&work
))
969 queue_quiesced_migrations(cache
, &work
);
972 static void quiesce_migration(struct dm_cache_migration
*mg
)
974 if (!dm_deferred_set_add_work(mg
->cache
->all_io_ds
, &mg
->list
))
975 queue_quiesced_migration(mg
);
978 static void promote(struct cache
*cache
, struct prealloc
*structs
,
979 dm_oblock_t oblock
, dm_cblock_t cblock
,
980 struct dm_bio_prison_cell
*cell
)
982 struct dm_cache_migration
*mg
= prealloc_get_migration(structs
);
985 mg
->writeback
= false;
989 mg
->new_oblock
= oblock
;
991 mg
->old_ocell
= NULL
;
992 mg
->new_ocell
= cell
;
993 mg
->start_jiffies
= jiffies
;
995 inc_nr_migrations(cache
);
996 quiesce_migration(mg
);
999 static void writeback(struct cache
*cache
, struct prealloc
*structs
,
1000 dm_oblock_t oblock
, dm_cblock_t cblock
,
1001 struct dm_bio_prison_cell
*cell
)
1003 struct dm_cache_migration
*mg
= prealloc_get_migration(structs
);
1006 mg
->writeback
= true;
1008 mg
->promote
= false;
1010 mg
->old_oblock
= oblock
;
1011 mg
->cblock
= cblock
;
1012 mg
->old_ocell
= cell
;
1013 mg
->new_ocell
= NULL
;
1014 mg
->start_jiffies
= jiffies
;
1016 inc_nr_migrations(cache
);
1017 quiesce_migration(mg
);
1020 static void demote_then_promote(struct cache
*cache
, struct prealloc
*structs
,
1021 dm_oblock_t old_oblock
, dm_oblock_t new_oblock
,
1023 struct dm_bio_prison_cell
*old_ocell
,
1024 struct dm_bio_prison_cell
*new_ocell
)
1026 struct dm_cache_migration
*mg
= prealloc_get_migration(structs
);
1029 mg
->writeback
= false;
1033 mg
->old_oblock
= old_oblock
;
1034 mg
->new_oblock
= new_oblock
;
1035 mg
->cblock
= cblock
;
1036 mg
->old_ocell
= old_ocell
;
1037 mg
->new_ocell
= new_ocell
;
1038 mg
->start_jiffies
= jiffies
;
1040 inc_nr_migrations(cache
);
1041 quiesce_migration(mg
);
1044 /*----------------------------------------------------------------
1046 *--------------------------------------------------------------*/
1047 static void defer_bio(struct cache
*cache
, struct bio
*bio
)
1049 unsigned long flags
;
1051 spin_lock_irqsave(&cache
->lock
, flags
);
1052 bio_list_add(&cache
->deferred_bios
, bio
);
1053 spin_unlock_irqrestore(&cache
->lock
, flags
);
1058 static void process_flush_bio(struct cache
*cache
, struct bio
*bio
)
1060 size_t pb_data_size
= get_per_bio_data_size(cache
);
1061 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
1063 BUG_ON(bio
->bi_size
);
1065 remap_to_origin(cache
, bio
);
1067 remap_to_cache(cache
, bio
, 0);
1073 * People generally discard large parts of a device, eg, the whole device
1074 * when formatting. Splitting these large discards up into cache block
1075 * sized ios and then quiescing (always neccessary for discard) takes too
1078 * We keep it simple, and allow any size of discard to come in, and just
1079 * mark off blocks on the discard bitset. No passdown occurs!
1081 * To implement passdown we need to change the bio_prison such that a cell
1082 * can have a key that spans many blocks.
1084 static void process_discard_bio(struct cache
*cache
, struct bio
*bio
)
1086 dm_block_t start_block
= dm_sector_div_up(bio
->bi_sector
,
1087 cache
->discard_block_size
);
1088 dm_block_t end_block
= bio
->bi_sector
+ bio_sectors(bio
);
1091 end_block
= block_div(end_block
, cache
->discard_block_size
);
1093 for (b
= start_block
; b
< end_block
; b
++)
1094 set_discard(cache
, to_dblock(b
));
1099 static bool spare_migration_bandwidth(struct cache
*cache
)
1101 sector_t current_volume
= (atomic_read(&cache
->nr_migrations
) + 1) *
1102 cache
->sectors_per_block
;
1103 return current_volume
< cache
->migration_threshold
;
1106 static bool is_writethrough_io(struct cache
*cache
, struct bio
*bio
,
1109 return bio_data_dir(bio
) == WRITE
&&
1110 cache
->features
.write_through
&& !is_dirty(cache
, cblock
);
1113 static void inc_hit_counter(struct cache
*cache
, struct bio
*bio
)
1115 atomic_inc(bio_data_dir(bio
) == READ
?
1116 &cache
->stats
.read_hit
: &cache
->stats
.write_hit
);
1119 static void inc_miss_counter(struct cache
*cache
, struct bio
*bio
)
1121 atomic_inc(bio_data_dir(bio
) == READ
?
1122 &cache
->stats
.read_miss
: &cache
->stats
.write_miss
);
1125 static void process_bio(struct cache
*cache
, struct prealloc
*structs
,
1129 bool release_cell
= true;
1130 dm_oblock_t block
= get_bio_block(cache
, bio
);
1131 struct dm_bio_prison_cell
*cell_prealloc
, *old_ocell
, *new_ocell
;
1132 struct policy_result lookup_result
;
1133 size_t pb_data_size
= get_per_bio_data_size(cache
);
1134 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
1135 bool discarded_block
= is_discarded_oblock(cache
, block
);
1136 bool can_migrate
= discarded_block
|| spare_migration_bandwidth(cache
);
1139 * Check to see if that block is currently migrating.
1141 cell_prealloc
= prealloc_get_cell(structs
);
1142 r
= bio_detain(cache
, block
, bio
, cell_prealloc
,
1143 (cell_free_fn
) prealloc_put_cell
,
1144 structs
, &new_ocell
);
1148 r
= policy_map(cache
->policy
, block
, true, can_migrate
, discarded_block
,
1149 bio
, &lookup_result
);
1151 if (r
== -EWOULDBLOCK
)
1152 /* migration has been denied */
1153 lookup_result
.op
= POLICY_MISS
;
1155 switch (lookup_result
.op
) {
1157 inc_hit_counter(cache
, bio
);
1158 pb
->all_io_entry
= dm_deferred_entry_inc(cache
->all_io_ds
);
1160 if (is_writethrough_io(cache
, bio
, lookup_result
.cblock
))
1161 remap_to_origin_then_cache(cache
, bio
, block
, lookup_result
.cblock
);
1163 remap_to_cache_dirty(cache
, bio
, block
, lookup_result
.cblock
);
1169 inc_miss_counter(cache
, bio
);
1170 pb
->all_io_entry
= dm_deferred_entry_inc(cache
->all_io_ds
);
1171 remap_to_origin_clear_discard(cache
, bio
, block
);
1176 atomic_inc(&cache
->stats
.promotion
);
1177 promote(cache
, structs
, block
, lookup_result
.cblock
, new_ocell
);
1178 release_cell
= false;
1181 case POLICY_REPLACE
:
1182 cell_prealloc
= prealloc_get_cell(structs
);
1183 r
= bio_detain(cache
, lookup_result
.old_oblock
, bio
, cell_prealloc
,
1184 (cell_free_fn
) prealloc_put_cell
,
1185 structs
, &old_ocell
);
1188 * We have to be careful to avoid lock inversion of
1189 * the cells. So we back off, and wait for the
1190 * old_ocell to become free.
1192 policy_force_mapping(cache
->policy
, block
,
1193 lookup_result
.old_oblock
);
1194 atomic_inc(&cache
->stats
.cache_cell_clash
);
1197 atomic_inc(&cache
->stats
.demotion
);
1198 atomic_inc(&cache
->stats
.promotion
);
1200 demote_then_promote(cache
, structs
, lookup_result
.old_oblock
,
1201 block
, lookup_result
.cblock
,
1202 old_ocell
, new_ocell
);
1203 release_cell
= false;
1207 DMERR_LIMIT("%s: erroring bio, unknown policy op: %u", __func__
,
1208 (unsigned) lookup_result
.op
);
1213 cell_defer(cache
, new_ocell
, false);
1216 static int need_commit_due_to_time(struct cache
*cache
)
1218 return jiffies
< cache
->last_commit_jiffies
||
1219 jiffies
> cache
->last_commit_jiffies
+ COMMIT_PERIOD
;
1222 static int commit_if_needed(struct cache
*cache
)
1224 if (dm_cache_changed_this_transaction(cache
->cmd
) &&
1225 (cache
->commit_requested
|| need_commit_due_to_time(cache
))) {
1226 atomic_inc(&cache
->stats
.commit_count
);
1227 cache
->last_commit_jiffies
= jiffies
;
1228 cache
->commit_requested
= false;
1229 return dm_cache_commit(cache
->cmd
, false);
1235 static void process_deferred_bios(struct cache
*cache
)
1237 unsigned long flags
;
1238 struct bio_list bios
;
1240 struct prealloc structs
;
1242 memset(&structs
, 0, sizeof(structs
));
1243 bio_list_init(&bios
);
1245 spin_lock_irqsave(&cache
->lock
, flags
);
1246 bio_list_merge(&bios
, &cache
->deferred_bios
);
1247 bio_list_init(&cache
->deferred_bios
);
1248 spin_unlock_irqrestore(&cache
->lock
, flags
);
1250 while (!bio_list_empty(&bios
)) {
1252 * If we've got no free migration structs, and processing
1253 * this bio might require one, we pause until there are some
1254 * prepared mappings to process.
1256 if (prealloc_data_structs(cache
, &structs
)) {
1257 spin_lock_irqsave(&cache
->lock
, flags
);
1258 bio_list_merge(&cache
->deferred_bios
, &bios
);
1259 spin_unlock_irqrestore(&cache
->lock
, flags
);
1263 bio
= bio_list_pop(&bios
);
1265 if (bio
->bi_rw
& REQ_FLUSH
)
1266 process_flush_bio(cache
, bio
);
1267 else if (bio
->bi_rw
& REQ_DISCARD
)
1268 process_discard_bio(cache
, bio
);
1270 process_bio(cache
, &structs
, bio
);
1273 prealloc_free_structs(cache
, &structs
);
1276 static void process_deferred_flush_bios(struct cache
*cache
, bool submit_bios
)
1278 unsigned long flags
;
1279 struct bio_list bios
;
1282 bio_list_init(&bios
);
1284 spin_lock_irqsave(&cache
->lock
, flags
);
1285 bio_list_merge(&bios
, &cache
->deferred_flush_bios
);
1286 bio_list_init(&cache
->deferred_flush_bios
);
1287 spin_unlock_irqrestore(&cache
->lock
, flags
);
1289 while ((bio
= bio_list_pop(&bios
)))
1290 submit_bios
? generic_make_request(bio
) : bio_io_error(bio
);
1293 static void process_deferred_writethrough_bios(struct cache
*cache
)
1295 unsigned long flags
;
1296 struct bio_list bios
;
1299 bio_list_init(&bios
);
1301 spin_lock_irqsave(&cache
->lock
, flags
);
1302 bio_list_merge(&bios
, &cache
->deferred_writethrough_bios
);
1303 bio_list_init(&cache
->deferred_writethrough_bios
);
1304 spin_unlock_irqrestore(&cache
->lock
, flags
);
1306 while ((bio
= bio_list_pop(&bios
)))
1307 generic_make_request(bio
);
1310 static void writeback_some_dirty_blocks(struct cache
*cache
)
1315 struct prealloc structs
;
1316 struct dm_bio_prison_cell
*old_ocell
;
1318 memset(&structs
, 0, sizeof(structs
));
1320 while (spare_migration_bandwidth(cache
)) {
1321 if (prealloc_data_structs(cache
, &structs
))
1324 r
= policy_writeback_work(cache
->policy
, &oblock
, &cblock
);
1328 r
= get_cell(cache
, oblock
, &structs
, &old_ocell
);
1330 policy_set_dirty(cache
->policy
, oblock
);
1334 writeback(cache
, &structs
, oblock
, cblock
, old_ocell
);
1337 prealloc_free_structs(cache
, &structs
);
1340 /*----------------------------------------------------------------
1342 *--------------------------------------------------------------*/
1343 static void start_quiescing(struct cache
*cache
)
1345 unsigned long flags
;
1347 spin_lock_irqsave(&cache
->lock
, flags
);
1348 cache
->quiescing
= 1;
1349 spin_unlock_irqrestore(&cache
->lock
, flags
);
1352 static void stop_quiescing(struct cache
*cache
)
1354 unsigned long flags
;
1356 spin_lock_irqsave(&cache
->lock
, flags
);
1357 cache
->quiescing
= 0;
1358 spin_unlock_irqrestore(&cache
->lock
, flags
);
1361 static bool is_quiescing(struct cache
*cache
)
1364 unsigned long flags
;
1366 spin_lock_irqsave(&cache
->lock
, flags
);
1367 r
= cache
->quiescing
;
1368 spin_unlock_irqrestore(&cache
->lock
, flags
);
1373 static void wait_for_migrations(struct cache
*cache
)
1375 wait_event(cache
->migration_wait
, !atomic_read(&cache
->nr_migrations
));
1378 static void stop_worker(struct cache
*cache
)
1380 cancel_delayed_work(&cache
->waker
);
1381 flush_workqueue(cache
->wq
);
1384 static void requeue_deferred_io(struct cache
*cache
)
1387 struct bio_list bios
;
1389 bio_list_init(&bios
);
1390 bio_list_merge(&bios
, &cache
->deferred_bios
);
1391 bio_list_init(&cache
->deferred_bios
);
1393 while ((bio
= bio_list_pop(&bios
)))
1394 bio_endio(bio
, DM_ENDIO_REQUEUE
);
1397 static int more_work(struct cache
*cache
)
1399 if (is_quiescing(cache
))
1400 return !list_empty(&cache
->quiesced_migrations
) ||
1401 !list_empty(&cache
->completed_migrations
) ||
1402 !list_empty(&cache
->need_commit_migrations
);
1404 return !bio_list_empty(&cache
->deferred_bios
) ||
1405 !bio_list_empty(&cache
->deferred_flush_bios
) ||
1406 !bio_list_empty(&cache
->deferred_writethrough_bios
) ||
1407 !list_empty(&cache
->quiesced_migrations
) ||
1408 !list_empty(&cache
->completed_migrations
) ||
1409 !list_empty(&cache
->need_commit_migrations
);
1412 static void do_worker(struct work_struct
*ws
)
1414 struct cache
*cache
= container_of(ws
, struct cache
, worker
);
1417 if (!is_quiescing(cache
))
1418 process_deferred_bios(cache
);
1420 process_migrations(cache
, &cache
->quiesced_migrations
, issue_copy
);
1421 process_migrations(cache
, &cache
->completed_migrations
, complete_migration
);
1423 writeback_some_dirty_blocks(cache
);
1425 process_deferred_writethrough_bios(cache
);
1427 if (commit_if_needed(cache
)) {
1428 process_deferred_flush_bios(cache
, false);
1431 * FIXME: rollback metadata or just go into a
1432 * failure mode and error everything
1435 process_deferred_flush_bios(cache
, true);
1436 process_migrations(cache
, &cache
->need_commit_migrations
,
1437 migration_success_post_commit
);
1439 } while (more_work(cache
));
1443 * We want to commit periodically so that not too much
1444 * unwritten metadata builds up.
1446 static void do_waker(struct work_struct
*ws
)
1448 struct cache
*cache
= container_of(to_delayed_work(ws
), struct cache
, waker
);
1449 policy_tick(cache
->policy
);
1451 queue_delayed_work(cache
->wq
, &cache
->waker
, COMMIT_PERIOD
);
1454 /*----------------------------------------------------------------*/
1456 static int is_congested(struct dm_dev
*dev
, int bdi_bits
)
1458 struct request_queue
*q
= bdev_get_queue(dev
->bdev
);
1459 return bdi_congested(&q
->backing_dev_info
, bdi_bits
);
1462 static int cache_is_congested(struct dm_target_callbacks
*cb
, int bdi_bits
)
1464 struct cache
*cache
= container_of(cb
, struct cache
, callbacks
);
1466 return is_congested(cache
->origin_dev
, bdi_bits
) ||
1467 is_congested(cache
->cache_dev
, bdi_bits
);
1470 /*----------------------------------------------------------------
1472 *--------------------------------------------------------------*/
1475 * This function gets called on the error paths of the constructor, so we
1476 * have to cope with a partially initialised struct.
1478 static void destroy(struct cache
*cache
)
1482 if (cache
->next_migration
)
1483 mempool_free(cache
->next_migration
, cache
->migration_pool
);
1485 if (cache
->migration_pool
)
1486 mempool_destroy(cache
->migration_pool
);
1488 if (cache
->all_io_ds
)
1489 dm_deferred_set_destroy(cache
->all_io_ds
);
1492 dm_bio_prison_destroy(cache
->prison
);
1495 destroy_workqueue(cache
->wq
);
1497 if (cache
->dirty_bitset
)
1498 free_bitset(cache
->dirty_bitset
);
1500 if (cache
->discard_bitset
)
1501 free_bitset(cache
->discard_bitset
);
1504 dm_kcopyd_client_destroy(cache
->copier
);
1507 dm_cache_metadata_close(cache
->cmd
);
1509 if (cache
->metadata_dev
)
1510 dm_put_device(cache
->ti
, cache
->metadata_dev
);
1512 if (cache
->origin_dev
)
1513 dm_put_device(cache
->ti
, cache
->origin_dev
);
1515 if (cache
->cache_dev
)
1516 dm_put_device(cache
->ti
, cache
->cache_dev
);
1519 dm_cache_policy_destroy(cache
->policy
);
1521 for (i
= 0; i
< cache
->nr_ctr_args
; i
++)
1522 kfree(cache
->ctr_args
[i
]);
1523 kfree(cache
->ctr_args
);
1528 static void cache_dtr(struct dm_target
*ti
)
1530 struct cache
*cache
= ti
->private;
1535 static sector_t
get_dev_size(struct dm_dev
*dev
)
1537 return i_size_read(dev
->bdev
->bd_inode
) >> SECTOR_SHIFT
;
1540 /*----------------------------------------------------------------*/
1543 * Construct a cache device mapping.
1545 * cache <metadata dev> <cache dev> <origin dev> <block size>
1546 * <#feature args> [<feature arg>]*
1547 * <policy> <#policy args> [<policy arg>]*
1549 * metadata dev : fast device holding the persistent metadata
1550 * cache dev : fast device holding cached data blocks
1551 * origin dev : slow device holding original data blocks
1552 * block size : cache unit size in sectors
1554 * #feature args : number of feature arguments passed
1555 * feature args : writethrough. (The default is writeback.)
1557 * policy : the replacement policy to use
1558 * #policy args : an even number of policy arguments corresponding
1559 * to key/value pairs passed to the policy
1560 * policy args : key/value pairs passed to the policy
1561 * E.g. 'sequential_threshold 1024'
1562 * See cache-policies.txt for details.
1564 * Optional feature arguments are:
1565 * writethrough : write through caching that prohibits cache block
1566 * content from being different from origin block content.
1567 * Without this argument, the default behaviour is to write
1568 * back cache block contents later for performance reasons,
1569 * so they may differ from the corresponding origin blocks.
1572 struct dm_target
*ti
;
1574 struct dm_dev
*metadata_dev
;
1576 struct dm_dev
*cache_dev
;
1577 sector_t cache_sectors
;
1579 struct dm_dev
*origin_dev
;
1580 sector_t origin_sectors
;
1582 uint32_t block_size
;
1584 const char *policy_name
;
1586 const char **policy_argv
;
1588 struct cache_features features
;
1591 static void destroy_cache_args(struct cache_args
*ca
)
1593 if (ca
->metadata_dev
)
1594 dm_put_device(ca
->ti
, ca
->metadata_dev
);
1597 dm_put_device(ca
->ti
, ca
->cache_dev
);
1600 dm_put_device(ca
->ti
, ca
->origin_dev
);
1605 static bool at_least_one_arg(struct dm_arg_set
*as
, char **error
)
1608 *error
= "Insufficient args";
1615 static int parse_metadata_dev(struct cache_args
*ca
, struct dm_arg_set
*as
,
1619 sector_t metadata_dev_size
;
1620 char b
[BDEVNAME_SIZE
];
1622 if (!at_least_one_arg(as
, error
))
1625 r
= dm_get_device(ca
->ti
, dm_shift_arg(as
), FMODE_READ
| FMODE_WRITE
,
1628 *error
= "Error opening metadata device";
1632 metadata_dev_size
= get_dev_size(ca
->metadata_dev
);
1633 if (metadata_dev_size
> DM_CACHE_METADATA_MAX_SECTORS_WARNING
)
1634 DMWARN("Metadata device %s is larger than %u sectors: excess space will not be used.",
1635 bdevname(ca
->metadata_dev
->bdev
, b
), THIN_METADATA_MAX_SECTORS
);
1640 static int parse_cache_dev(struct cache_args
*ca
, struct dm_arg_set
*as
,
1645 if (!at_least_one_arg(as
, error
))
1648 r
= dm_get_device(ca
->ti
, dm_shift_arg(as
), FMODE_READ
| FMODE_WRITE
,
1651 *error
= "Error opening cache device";
1654 ca
->cache_sectors
= get_dev_size(ca
->cache_dev
);
1659 static int parse_origin_dev(struct cache_args
*ca
, struct dm_arg_set
*as
,
1664 if (!at_least_one_arg(as
, error
))
1667 r
= dm_get_device(ca
->ti
, dm_shift_arg(as
), FMODE_READ
| FMODE_WRITE
,
1670 *error
= "Error opening origin device";
1674 ca
->origin_sectors
= get_dev_size(ca
->origin_dev
);
1675 if (ca
->ti
->len
> ca
->origin_sectors
) {
1676 *error
= "Device size larger than cached device";
1683 static int parse_block_size(struct cache_args
*ca
, struct dm_arg_set
*as
,
1688 if (!at_least_one_arg(as
, error
))
1691 if (kstrtoul(dm_shift_arg(as
), 10, &tmp
) || !tmp
||
1692 tmp
< DATA_DEV_BLOCK_SIZE_MIN_SECTORS
||
1693 tmp
& (DATA_DEV_BLOCK_SIZE_MIN_SECTORS
- 1)) {
1694 *error
= "Invalid data block size";
1698 if (tmp
> ca
->cache_sectors
) {
1699 *error
= "Data block size is larger than the cache device";
1703 ca
->block_size
= tmp
;
1708 static void init_features(struct cache_features
*cf
)
1710 cf
->mode
= CM_WRITE
;
1711 cf
->write_through
= false;
1714 static int parse_features(struct cache_args
*ca
, struct dm_arg_set
*as
,
1717 static struct dm_arg _args
[] = {
1718 {0, 1, "Invalid number of cache feature arguments"},
1724 struct cache_features
*cf
= &ca
->features
;
1728 r
= dm_read_arg_group(_args
, as
, &argc
, error
);
1733 arg
= dm_shift_arg(as
);
1735 if (!strcasecmp(arg
, "writeback"))
1736 cf
->write_through
= false;
1738 else if (!strcasecmp(arg
, "writethrough"))
1739 cf
->write_through
= true;
1742 *error
= "Unrecognised cache feature requested";
1750 static int parse_policy(struct cache_args
*ca
, struct dm_arg_set
*as
,
1753 static struct dm_arg _args
[] = {
1754 {0, 1024, "Invalid number of policy arguments"},
1759 if (!at_least_one_arg(as
, error
))
1762 ca
->policy_name
= dm_shift_arg(as
);
1764 r
= dm_read_arg_group(_args
, as
, &ca
->policy_argc
, error
);
1768 ca
->policy_argv
= (const char **)as
->argv
;
1769 dm_consume_args(as
, ca
->policy_argc
);
1774 static int parse_cache_args(struct cache_args
*ca
, int argc
, char **argv
,
1778 struct dm_arg_set as
;
1783 r
= parse_metadata_dev(ca
, &as
, error
);
1787 r
= parse_cache_dev(ca
, &as
, error
);
1791 r
= parse_origin_dev(ca
, &as
, error
);
1795 r
= parse_block_size(ca
, &as
, error
);
1799 r
= parse_features(ca
, &as
, error
);
1803 r
= parse_policy(ca
, &as
, error
);
1810 /*----------------------------------------------------------------*/
1812 static struct kmem_cache
*migration_cache
;
1814 static int set_config_values(struct dm_cache_policy
*p
, int argc
, const char **argv
)
1819 DMWARN("Odd number of policy arguments given but they should be <key> <value> pairs.");
1824 r
= policy_set_config_value(p
, argv
[0], argv
[1]);
1826 DMWARN("policy_set_config_value failed: key = '%s', value = '%s'",
1838 static int create_cache_policy(struct cache
*cache
, struct cache_args
*ca
,
1843 cache
->policy
= dm_cache_policy_create(ca
->policy_name
,
1845 cache
->origin_sectors
,
1846 cache
->sectors_per_block
);
1847 if (!cache
->policy
) {
1848 *error
= "Error creating cache's policy";
1852 r
= set_config_values(cache
->policy
, ca
->policy_argc
, ca
->policy_argv
);
1854 *error
= "Error setting cache policy's config values";
1855 dm_cache_policy_destroy(cache
->policy
);
1856 cache
->policy
= NULL
;
1863 * We want the discard block size to be a power of two, at least the size
1864 * of the cache block size, and have no more than 2^14 discard blocks
1865 * across the origin.
1867 #define MAX_DISCARD_BLOCKS (1 << 14)
1869 static bool too_many_discard_blocks(sector_t discard_block_size
,
1870 sector_t origin_size
)
1872 (void) sector_div(origin_size
, discard_block_size
);
1874 return origin_size
> MAX_DISCARD_BLOCKS
;
1877 static sector_t
calculate_discard_block_size(sector_t cache_block_size
,
1878 sector_t origin_size
)
1880 sector_t discard_block_size
;
1882 discard_block_size
= roundup_pow_of_two(cache_block_size
);
1885 while (too_many_discard_blocks(discard_block_size
, origin_size
))
1886 discard_block_size
*= 2;
1888 return discard_block_size
;
1891 #define DEFAULT_MIGRATION_THRESHOLD 2048
1893 static int cache_create(struct cache_args
*ca
, struct cache
**result
)
1896 char **error
= &ca
->ti
->error
;
1897 struct cache
*cache
;
1898 struct dm_target
*ti
= ca
->ti
;
1899 dm_block_t origin_blocks
;
1900 struct dm_cache_metadata
*cmd
;
1901 bool may_format
= ca
->features
.mode
== CM_WRITE
;
1903 cache
= kzalloc(sizeof(*cache
), GFP_KERNEL
);
1908 ti
->private = cache
;
1909 ti
->num_flush_bios
= 2;
1910 ti
->flush_supported
= true;
1912 ti
->num_discard_bios
= 1;
1913 ti
->discards_supported
= true;
1914 ti
->discard_zeroes_data_unsupported
= true;
1916 memcpy(&cache
->features
, &ca
->features
, sizeof(cache
->features
));
1917 ti
->per_bio_data_size
= get_per_bio_data_size(cache
);
1919 cache
->callbacks
.congested_fn
= cache_is_congested
;
1920 dm_table_add_target_callbacks(ti
->table
, &cache
->callbacks
);
1922 cache
->metadata_dev
= ca
->metadata_dev
;
1923 cache
->origin_dev
= ca
->origin_dev
;
1924 cache
->cache_dev
= ca
->cache_dev
;
1926 ca
->metadata_dev
= ca
->origin_dev
= ca
->cache_dev
= NULL
;
1928 /* FIXME: factor out this whole section */
1929 origin_blocks
= cache
->origin_sectors
= ca
->origin_sectors
;
1930 origin_blocks
= block_div(origin_blocks
, ca
->block_size
);
1931 cache
->origin_blocks
= to_oblock(origin_blocks
);
1933 cache
->sectors_per_block
= ca
->block_size
;
1934 if (dm_set_target_max_io_len(ti
, cache
->sectors_per_block
)) {
1939 if (ca
->block_size
& (ca
->block_size
- 1)) {
1940 dm_block_t cache_size
= ca
->cache_sectors
;
1942 cache
->sectors_per_block_shift
= -1;
1943 cache_size
= block_div(cache_size
, ca
->block_size
);
1944 cache
->cache_size
= to_cblock(cache_size
);
1946 cache
->sectors_per_block_shift
= __ffs(ca
->block_size
);
1947 cache
->cache_size
= to_cblock(ca
->cache_sectors
>> cache
->sectors_per_block_shift
);
1950 r
= create_cache_policy(cache
, ca
, error
);
1953 cache
->policy_nr_args
= ca
->policy_argc
;
1955 cmd
= dm_cache_metadata_open(cache
->metadata_dev
->bdev
,
1956 ca
->block_size
, may_format
,
1957 dm_cache_policy_get_hint_size(cache
->policy
));
1959 *error
= "Error creating metadata object";
1965 spin_lock_init(&cache
->lock
);
1966 bio_list_init(&cache
->deferred_bios
);
1967 bio_list_init(&cache
->deferred_flush_bios
);
1968 bio_list_init(&cache
->deferred_writethrough_bios
);
1969 INIT_LIST_HEAD(&cache
->quiesced_migrations
);
1970 INIT_LIST_HEAD(&cache
->completed_migrations
);
1971 INIT_LIST_HEAD(&cache
->need_commit_migrations
);
1972 cache
->migration_threshold
= DEFAULT_MIGRATION_THRESHOLD
;
1973 atomic_set(&cache
->nr_migrations
, 0);
1974 init_waitqueue_head(&cache
->migration_wait
);
1977 cache
->nr_dirty
= 0;
1978 cache
->dirty_bitset
= alloc_bitset(from_cblock(cache
->cache_size
));
1979 if (!cache
->dirty_bitset
) {
1980 *error
= "could not allocate dirty bitset";
1983 clear_bitset(cache
->dirty_bitset
, from_cblock(cache
->cache_size
));
1985 cache
->discard_block_size
=
1986 calculate_discard_block_size(cache
->sectors_per_block
,
1987 cache
->origin_sectors
);
1988 cache
->discard_nr_blocks
= oblock_to_dblock(cache
, cache
->origin_blocks
);
1989 cache
->discard_bitset
= alloc_bitset(from_dblock(cache
->discard_nr_blocks
));
1990 if (!cache
->discard_bitset
) {
1991 *error
= "could not allocate discard bitset";
1994 clear_bitset(cache
->discard_bitset
, from_dblock(cache
->discard_nr_blocks
));
1996 cache
->copier
= dm_kcopyd_client_create(&dm_kcopyd_throttle
);
1997 if (IS_ERR(cache
->copier
)) {
1998 *error
= "could not create kcopyd client";
1999 r
= PTR_ERR(cache
->copier
);
2003 cache
->wq
= alloc_ordered_workqueue("dm-" DM_MSG_PREFIX
, WQ_MEM_RECLAIM
);
2005 *error
= "could not create workqueue for metadata object";
2008 INIT_WORK(&cache
->worker
, do_worker
);
2009 INIT_DELAYED_WORK(&cache
->waker
, do_waker
);
2010 cache
->last_commit_jiffies
= jiffies
;
2012 cache
->prison
= dm_bio_prison_create(PRISON_CELLS
);
2013 if (!cache
->prison
) {
2014 *error
= "could not create bio prison";
2018 cache
->all_io_ds
= dm_deferred_set_create();
2019 if (!cache
->all_io_ds
) {
2020 *error
= "could not create all_io deferred set";
2024 cache
->migration_pool
= mempool_create_slab_pool(MIGRATION_POOL_SIZE
,
2026 if (!cache
->migration_pool
) {
2027 *error
= "Error creating cache's migration mempool";
2031 cache
->next_migration
= NULL
;
2033 cache
->need_tick_bio
= true;
2034 cache
->sized
= false;
2035 cache
->quiescing
= false;
2036 cache
->commit_requested
= false;
2037 cache
->loaded_mappings
= false;
2038 cache
->loaded_discards
= false;
2042 atomic_set(&cache
->stats
.demotion
, 0);
2043 atomic_set(&cache
->stats
.promotion
, 0);
2044 atomic_set(&cache
->stats
.copies_avoided
, 0);
2045 atomic_set(&cache
->stats
.cache_cell_clash
, 0);
2046 atomic_set(&cache
->stats
.commit_count
, 0);
2047 atomic_set(&cache
->stats
.discard_count
, 0);
2057 static int copy_ctr_args(struct cache
*cache
, int argc
, const char **argv
)
2062 copy
= kcalloc(argc
, sizeof(*copy
), GFP_KERNEL
);
2065 for (i
= 0; i
< argc
; i
++) {
2066 copy
[i
] = kstrdup(argv
[i
], GFP_KERNEL
);
2075 cache
->nr_ctr_args
= argc
;
2076 cache
->ctr_args
= copy
;
2081 static int cache_ctr(struct dm_target
*ti
, unsigned argc
, char **argv
)
2084 struct cache_args
*ca
;
2085 struct cache
*cache
= NULL
;
2087 ca
= kzalloc(sizeof(*ca
), GFP_KERNEL
);
2089 ti
->error
= "Error allocating memory for cache";
2094 r
= parse_cache_args(ca
, argc
, argv
, &ti
->error
);
2098 r
= cache_create(ca
, &cache
);
2102 r
= copy_ctr_args(cache
, argc
- 3, (const char **)argv
+ 3);
2108 ti
->private = cache
;
2111 destroy_cache_args(ca
);
2115 static int cache_map(struct dm_target
*ti
, struct bio
*bio
)
2117 struct cache
*cache
= ti
->private;
2120 dm_oblock_t block
= get_bio_block(cache
, bio
);
2121 size_t pb_data_size
= get_per_bio_data_size(cache
);
2122 bool can_migrate
= false;
2123 bool discarded_block
;
2124 struct dm_bio_prison_cell
*cell
;
2125 struct policy_result lookup_result
;
2126 struct per_bio_data
*pb
;
2128 if (from_oblock(block
) > from_oblock(cache
->origin_blocks
)) {
2130 * This can only occur if the io goes to a partial block at
2131 * the end of the origin device. We don't cache these.
2132 * Just remap to the origin and carry on.
2134 remap_to_origin_clear_discard(cache
, bio
, block
);
2135 return DM_MAPIO_REMAPPED
;
2138 pb
= init_per_bio_data(bio
, pb_data_size
);
2140 if (bio
->bi_rw
& (REQ_FLUSH
| REQ_FUA
| REQ_DISCARD
)) {
2141 defer_bio(cache
, bio
);
2142 return DM_MAPIO_SUBMITTED
;
2146 * Check to see if that block is currently migrating.
2148 cell
= alloc_prison_cell(cache
);
2150 defer_bio(cache
, bio
);
2151 return DM_MAPIO_SUBMITTED
;
2154 r
= bio_detain(cache
, block
, bio
, cell
,
2155 (cell_free_fn
) free_prison_cell
,
2159 defer_bio(cache
, bio
);
2161 return DM_MAPIO_SUBMITTED
;
2164 discarded_block
= is_discarded_oblock(cache
, block
);
2166 r
= policy_map(cache
->policy
, block
, false, can_migrate
, discarded_block
,
2167 bio
, &lookup_result
);
2168 if (r
== -EWOULDBLOCK
) {
2169 cell_defer(cache
, cell
, true);
2170 return DM_MAPIO_SUBMITTED
;
2173 DMERR_LIMIT("Unexpected return from cache replacement policy: %d", r
);
2175 return DM_MAPIO_SUBMITTED
;
2178 switch (lookup_result
.op
) {
2180 inc_hit_counter(cache
, bio
);
2181 pb
->all_io_entry
= dm_deferred_entry_inc(cache
->all_io_ds
);
2183 if (is_writethrough_io(cache
, bio
, lookup_result
.cblock
))
2184 remap_to_origin_then_cache(cache
, bio
, block
, lookup_result
.cblock
);
2186 remap_to_cache_dirty(cache
, bio
, block
, lookup_result
.cblock
);
2188 cell_defer(cache
, cell
, false);
2192 inc_miss_counter(cache
, bio
);
2193 pb
->all_io_entry
= dm_deferred_entry_inc(cache
->all_io_ds
);
2195 if (pb
->req_nr
!= 0) {
2197 * This is a duplicate writethrough io that is no
2198 * longer needed because the block has been demoted.
2201 cell_defer(cache
, cell
, false);
2202 return DM_MAPIO_SUBMITTED
;
2204 remap_to_origin_clear_discard(cache
, bio
, block
);
2205 cell_defer(cache
, cell
, false);
2210 DMERR_LIMIT("%s: erroring bio: unknown policy op: %u", __func__
,
2211 (unsigned) lookup_result
.op
);
2213 return DM_MAPIO_SUBMITTED
;
2216 return DM_MAPIO_REMAPPED
;
2219 static int cache_end_io(struct dm_target
*ti
, struct bio
*bio
, int error
)
2221 struct cache
*cache
= ti
->private;
2222 unsigned long flags
;
2223 size_t pb_data_size
= get_per_bio_data_size(cache
);
2224 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
2227 policy_tick(cache
->policy
);
2229 spin_lock_irqsave(&cache
->lock
, flags
);
2230 cache
->need_tick_bio
= true;
2231 spin_unlock_irqrestore(&cache
->lock
, flags
);
2234 check_for_quiesced_migrations(cache
, pb
);
2239 static int write_dirty_bitset(struct cache
*cache
)
2243 for (i
= 0; i
< from_cblock(cache
->cache_size
); i
++) {
2244 r
= dm_cache_set_dirty(cache
->cmd
, to_cblock(i
),
2245 is_dirty(cache
, to_cblock(i
)));
2253 static int write_discard_bitset(struct cache
*cache
)
2257 r
= dm_cache_discard_bitset_resize(cache
->cmd
, cache
->discard_block_size
,
2258 cache
->discard_nr_blocks
);
2260 DMERR("could not resize on-disk discard bitset");
2264 for (i
= 0; i
< from_dblock(cache
->discard_nr_blocks
); i
++) {
2265 r
= dm_cache_set_discard(cache
->cmd
, to_dblock(i
),
2266 is_discarded(cache
, to_dblock(i
)));
2274 static int save_hint(void *context
, dm_cblock_t cblock
, dm_oblock_t oblock
,
2277 struct cache
*cache
= context
;
2278 return dm_cache_save_hint(cache
->cmd
, cblock
, hint
);
2281 static int write_hints(struct cache
*cache
)
2285 r
= dm_cache_begin_hints(cache
->cmd
, cache
->policy
);
2287 DMERR("dm_cache_begin_hints failed");
2291 r
= policy_walk_mappings(cache
->policy
, save_hint
, cache
);
2293 DMERR("policy_walk_mappings failed");
2299 * returns true on success
2301 static bool sync_metadata(struct cache
*cache
)
2305 r1
= write_dirty_bitset(cache
);
2307 DMERR("could not write dirty bitset");
2309 r2
= write_discard_bitset(cache
);
2311 DMERR("could not write discard bitset");
2315 r3
= write_hints(cache
);
2317 DMERR("could not write hints");
2320 * If writing the above metadata failed, we still commit, but don't
2321 * set the clean shutdown flag. This will effectively force every
2322 * dirty bit to be set on reload.
2324 r4
= dm_cache_commit(cache
->cmd
, !r1
&& !r2
&& !r3
);
2326 DMERR("could not write cache metadata. Data loss may occur.");
2328 return !r1
&& !r2
&& !r3
&& !r4
;
2331 static void cache_postsuspend(struct dm_target
*ti
)
2333 struct cache
*cache
= ti
->private;
2335 start_quiescing(cache
);
2336 wait_for_migrations(cache
);
2338 requeue_deferred_io(cache
);
2339 stop_quiescing(cache
);
2341 (void) sync_metadata(cache
);
2344 static int load_mapping(void *context
, dm_oblock_t oblock
, dm_cblock_t cblock
,
2345 bool dirty
, uint32_t hint
, bool hint_valid
)
2348 struct cache
*cache
= context
;
2350 r
= policy_load_mapping(cache
->policy
, oblock
, cblock
, hint
, hint_valid
);
2355 set_dirty(cache
, oblock
, cblock
);
2357 clear_dirty(cache
, oblock
, cblock
);
2362 static int load_discard(void *context
, sector_t discard_block_size
,
2363 dm_dblock_t dblock
, bool discard
)
2365 struct cache
*cache
= context
;
2367 /* FIXME: handle mis-matched block size */
2370 set_discard(cache
, dblock
);
2372 clear_discard(cache
, dblock
);
2377 static int cache_preresume(struct dm_target
*ti
)
2380 struct cache
*cache
= ti
->private;
2381 sector_t actual_cache_size
= get_dev_size(cache
->cache_dev
);
2382 (void) sector_div(actual_cache_size
, cache
->sectors_per_block
);
2385 * Check to see if the cache has resized.
2387 if (from_cblock(cache
->cache_size
) != actual_cache_size
|| !cache
->sized
) {
2388 cache
->cache_size
= to_cblock(actual_cache_size
);
2390 r
= dm_cache_resize(cache
->cmd
, cache
->cache_size
);
2392 DMERR("could not resize cache metadata");
2396 cache
->sized
= true;
2399 if (!cache
->loaded_mappings
) {
2400 r
= dm_cache_load_mappings(cache
->cmd
, cache
->policy
,
2401 load_mapping
, cache
);
2403 DMERR("could not load cache mappings");
2407 cache
->loaded_mappings
= true;
2410 if (!cache
->loaded_discards
) {
2411 r
= dm_cache_load_discards(cache
->cmd
, load_discard
, cache
);
2413 DMERR("could not load origin discards");
2417 cache
->loaded_discards
= true;
2423 static void cache_resume(struct dm_target
*ti
)
2425 struct cache
*cache
= ti
->private;
2427 cache
->need_tick_bio
= true;
2428 do_waker(&cache
->waker
.work
);
2434 * <#used metadata blocks>/<#total metadata blocks>
2435 * <#read hits> <#read misses> <#write hits> <#write misses>
2436 * <#demotions> <#promotions> <#blocks in cache> <#dirty>
2437 * <#features> <features>*
2438 * <#core args> <core args>
2439 * <#policy args> <policy args>*
2441 static void cache_status(struct dm_target
*ti
, status_type_t type
,
2442 unsigned status_flags
, char *result
, unsigned maxlen
)
2447 dm_block_t nr_free_blocks_metadata
= 0;
2448 dm_block_t nr_blocks_metadata
= 0;
2449 char buf
[BDEVNAME_SIZE
];
2450 struct cache
*cache
= ti
->private;
2451 dm_cblock_t residency
;
2454 case STATUSTYPE_INFO
:
2455 /* Commit to ensure statistics aren't out-of-date */
2456 if (!(status_flags
& DM_STATUS_NOFLUSH_FLAG
) && !dm_suspended(ti
)) {
2457 r
= dm_cache_commit(cache
->cmd
, false);
2459 DMERR("could not commit metadata for accurate status");
2462 r
= dm_cache_get_free_metadata_block_count(cache
->cmd
,
2463 &nr_free_blocks_metadata
);
2465 DMERR("could not get metadata free block count");
2469 r
= dm_cache_get_metadata_dev_size(cache
->cmd
, &nr_blocks_metadata
);
2471 DMERR("could not get metadata device size");
2475 residency
= policy_residency(cache
->policy
);
2477 DMEMIT("%llu/%llu %u %u %u %u %u %u %llu %u ",
2478 (unsigned long long)(nr_blocks_metadata
- nr_free_blocks_metadata
),
2479 (unsigned long long)nr_blocks_metadata
,
2480 (unsigned) atomic_read(&cache
->stats
.read_hit
),
2481 (unsigned) atomic_read(&cache
->stats
.read_miss
),
2482 (unsigned) atomic_read(&cache
->stats
.write_hit
),
2483 (unsigned) atomic_read(&cache
->stats
.write_miss
),
2484 (unsigned) atomic_read(&cache
->stats
.demotion
),
2485 (unsigned) atomic_read(&cache
->stats
.promotion
),
2486 (unsigned long long) from_cblock(residency
),
2489 if (cache
->features
.write_through
)
2490 DMEMIT("1 writethrough ");
2494 DMEMIT("2 migration_threshold %llu ", (unsigned long long) cache
->migration_threshold
);
2496 r
= policy_emit_config_values(cache
->policy
, result
+ sz
, maxlen
- sz
);
2498 DMERR("policy_emit_config_values returned %d", r
);
2503 case STATUSTYPE_TABLE
:
2504 format_dev_t(buf
, cache
->metadata_dev
->bdev
->bd_dev
);
2506 format_dev_t(buf
, cache
->cache_dev
->bdev
->bd_dev
);
2508 format_dev_t(buf
, cache
->origin_dev
->bdev
->bd_dev
);
2511 for (i
= 0; i
< cache
->nr_ctr_args
- 1; i
++)
2512 DMEMIT(" %s", cache
->ctr_args
[i
]);
2513 if (cache
->nr_ctr_args
)
2514 DMEMIT(" %s", cache
->ctr_args
[cache
->nr_ctr_args
- 1]);
2523 #define NOT_CORE_OPTION 1
2525 static int process_config_option(struct cache
*cache
, char **argv
)
2529 if (!strcasecmp(argv
[0], "migration_threshold")) {
2530 if (kstrtoul(argv
[1], 10, &tmp
))
2533 cache
->migration_threshold
= tmp
;
2537 return NOT_CORE_OPTION
;
2541 * Supports <key> <value>.
2543 * The key migration_threshold is supported by the cache target core.
2545 static int cache_message(struct dm_target
*ti
, unsigned argc
, char **argv
)
2548 struct cache
*cache
= ti
->private;
2553 r
= process_config_option(cache
, argv
);
2554 if (r
== NOT_CORE_OPTION
)
2555 return policy_set_config_value(cache
->policy
, argv
[0], argv
[1]);
2560 static int cache_iterate_devices(struct dm_target
*ti
,
2561 iterate_devices_callout_fn fn
, void *data
)
2564 struct cache
*cache
= ti
->private;
2566 r
= fn(ti
, cache
->cache_dev
, 0, get_dev_size(cache
->cache_dev
), data
);
2568 r
= fn(ti
, cache
->origin_dev
, 0, ti
->len
, data
);
2574 * We assume I/O is going to the origin (which is the volume
2575 * more likely to have restrictions e.g. by being striped).
2576 * (Looking up the exact location of the data would be expensive
2577 * and could always be out of date by the time the bio is submitted.)
2579 static int cache_bvec_merge(struct dm_target
*ti
,
2580 struct bvec_merge_data
*bvm
,
2581 struct bio_vec
*biovec
, int max_size
)
2583 struct cache
*cache
= ti
->private;
2584 struct request_queue
*q
= bdev_get_queue(cache
->origin_dev
->bdev
);
2586 if (!q
->merge_bvec_fn
)
2589 bvm
->bi_bdev
= cache
->origin_dev
->bdev
;
2590 return min(max_size
, q
->merge_bvec_fn(q
, bvm
, biovec
));
2593 static void set_discard_limits(struct cache
*cache
, struct queue_limits
*limits
)
2596 * FIXME: these limits may be incompatible with the cache device
2598 limits
->max_discard_sectors
= cache
->discard_block_size
* 1024;
2599 limits
->discard_granularity
= cache
->discard_block_size
<< SECTOR_SHIFT
;
2602 static void cache_io_hints(struct dm_target
*ti
, struct queue_limits
*limits
)
2604 struct cache
*cache
= ti
->private;
2606 blk_limits_io_min(limits
, 0);
2607 blk_limits_io_opt(limits
, cache
->sectors_per_block
<< SECTOR_SHIFT
);
2608 set_discard_limits(cache
, limits
);
2611 /*----------------------------------------------------------------*/
2613 static struct target_type cache_target
= {
2615 .version
= {1, 1, 0},
2616 .module
= THIS_MODULE
,
2620 .end_io
= cache_end_io
,
2621 .postsuspend
= cache_postsuspend
,
2622 .preresume
= cache_preresume
,
2623 .resume
= cache_resume
,
2624 .status
= cache_status
,
2625 .message
= cache_message
,
2626 .iterate_devices
= cache_iterate_devices
,
2627 .merge
= cache_bvec_merge
,
2628 .io_hints
= cache_io_hints
,
2631 static int __init
dm_cache_init(void)
2635 r
= dm_register_target(&cache_target
);
2637 DMERR("cache target registration failed: %d", r
);
2641 migration_cache
= KMEM_CACHE(dm_cache_migration
, 0);
2642 if (!migration_cache
) {
2643 dm_unregister_target(&cache_target
);
2650 static void __exit
dm_cache_exit(void)
2652 dm_unregister_target(&cache_target
);
2653 kmem_cache_destroy(migration_cache
);
2656 module_init(dm_cache_init
);
2657 module_exit(dm_cache_exit
);
2659 MODULE_DESCRIPTION(DM_NAME
" cache target");
2660 MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
2661 MODULE_LICENSE("GPL");