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 /*----------------------------------------------------------------*/
65 * There are a couple of places where we let a bio run, but want to do some
66 * work before calling its endio function. We do this by temporarily
67 * changing the endio fn.
70 bio_end_io_t
*bi_end_io
;
74 static void dm_hook_bio(struct dm_hook_info
*h
, struct bio
*bio
,
75 bio_end_io_t
*bi_end_io
, void *bi_private
)
77 h
->bi_end_io
= bio
->bi_end_io
;
78 h
->bi_private
= bio
->bi_private
;
80 bio
->bi_end_io
= bi_end_io
;
81 bio
->bi_private
= bi_private
;
84 static void dm_unhook_bio(struct dm_hook_info
*h
, struct bio
*bio
)
86 bio
->bi_end_io
= h
->bi_end_io
;
87 bio
->bi_private
= h
->bi_private
;
90 * Must bump bi_remaining to allow bio to complete with
93 atomic_inc(&bio
->bi_remaining
);
96 /*----------------------------------------------------------------*/
98 #define PRISON_CELLS 1024
99 #define MIGRATION_POOL_SIZE 128
100 #define COMMIT_PERIOD HZ
101 #define MIGRATION_COUNT_WINDOW 10
104 * The block size of the device holding cache data must be
105 * between 32KB and 1GB.
107 #define DATA_DEV_BLOCK_SIZE_MIN_SECTORS (32 * 1024 >> SECTOR_SHIFT)
108 #define DATA_DEV_BLOCK_SIZE_MAX_SECTORS (1024 * 1024 * 1024 >> SECTOR_SHIFT)
111 * FIXME: the cache is read/write for the time being.
113 enum cache_metadata_mode
{
114 CM_WRITE
, /* metadata may be changed */
115 CM_READ_ONLY
, /* metadata may not be changed */
120 * Data is written to cached blocks only. These blocks are marked
121 * dirty. If you lose the cache device you will lose data.
122 * Potential performance increase for both reads and writes.
127 * Data is written to both cache and origin. Blocks are never
128 * dirty. Potential performance benfit for reads only.
133 * A degraded mode useful for various cache coherency situations
134 * (eg, rolling back snapshots). Reads and writes always go to the
135 * origin. If a write goes to a cached oblock, then the cache
136 * block is invalidated.
141 struct cache_features
{
142 enum cache_metadata_mode mode
;
143 enum cache_io_mode io_mode
;
153 atomic_t copies_avoided
;
154 atomic_t cache_cell_clash
;
155 atomic_t commit_count
;
156 atomic_t discard_count
;
160 * Defines a range of cblocks, begin to (end - 1) are in the range. end is
161 * the one-past-the-end value.
163 struct cblock_range
{
168 struct invalidation_request
{
169 struct list_head list
;
170 struct cblock_range
*cblocks
;
175 wait_queue_head_t result_wait
;
179 struct dm_target
*ti
;
180 struct dm_target_callbacks callbacks
;
182 struct dm_cache_metadata
*cmd
;
185 * Metadata is written to this device.
187 struct dm_dev
*metadata_dev
;
190 * The slower of the two data devices. Typically a spindle.
192 struct dm_dev
*origin_dev
;
195 * The faster of the two data devices. Typically an SSD.
197 struct dm_dev
*cache_dev
;
200 * Size of the origin device in _complete_ blocks and native sectors.
202 dm_oblock_t origin_blocks
;
203 sector_t origin_sectors
;
206 * Size of the cache device in blocks.
208 dm_cblock_t cache_size
;
211 * Fields for converting from sectors to blocks.
213 uint32_t sectors_per_block
;
214 int sectors_per_block_shift
;
217 struct bio_list deferred_bios
;
218 struct bio_list deferred_flush_bios
;
219 struct bio_list deferred_writethrough_bios
;
220 struct list_head quiesced_migrations
;
221 struct list_head completed_migrations
;
222 struct list_head need_commit_migrations
;
223 sector_t migration_threshold
;
224 wait_queue_head_t migration_wait
;
225 atomic_t nr_migrations
;
227 wait_queue_head_t quiescing_wait
;
229 atomic_t quiescing_ack
;
232 * cache_size entries, dirty if set
235 unsigned long *dirty_bitset
;
238 * origin_blocks entries, discarded if set.
240 dm_oblock_t discard_nr_blocks
;
241 unsigned long *discard_bitset
;
244 * Rather than reconstructing the table line for the status we just
245 * save it and regurgitate.
247 unsigned nr_ctr_args
;
248 const char **ctr_args
;
250 struct dm_kcopyd_client
*copier
;
251 struct workqueue_struct
*wq
;
252 struct work_struct worker
;
254 struct delayed_work waker
;
255 unsigned long last_commit_jiffies
;
257 struct dm_bio_prison
*prison
;
258 struct dm_deferred_set
*all_io_ds
;
260 mempool_t
*migration_pool
;
261 struct dm_cache_migration
*next_migration
;
263 struct dm_cache_policy
*policy
;
264 unsigned policy_nr_args
;
266 bool need_tick_bio
:1;
269 bool commit_requested
:1;
270 bool loaded_mappings
:1;
271 bool loaded_discards
:1;
274 * Cache features such as write-through.
276 struct cache_features features
;
278 struct cache_stats stats
;
281 * Invalidation fields.
283 spinlock_t invalidation_lock
;
284 struct list_head invalidation_requests
;
287 struct per_bio_data
{
290 struct dm_deferred_entry
*all_io_entry
;
291 struct dm_hook_info hook_info
;
294 * writethrough fields. These MUST remain at the end of this
295 * structure and the 'cache' member must be the first as it
296 * is used to determine the offset of the writethrough fields.
300 struct dm_bio_details bio_details
;
303 struct dm_cache_migration
{
304 struct list_head list
;
307 unsigned long start_jiffies
;
308 dm_oblock_t old_oblock
;
309 dm_oblock_t new_oblock
;
316 bool requeue_holder
:1;
319 struct dm_bio_prison_cell
*old_ocell
;
320 struct dm_bio_prison_cell
*new_ocell
;
324 * Processing a bio in the worker thread may require these memory
325 * allocations. We prealloc to avoid deadlocks (the same worker thread
326 * frees them back to the mempool).
329 struct dm_cache_migration
*mg
;
330 struct dm_bio_prison_cell
*cell1
;
331 struct dm_bio_prison_cell
*cell2
;
334 static void wake_worker(struct cache
*cache
)
336 queue_work(cache
->wq
, &cache
->worker
);
339 /*----------------------------------------------------------------*/
341 static struct dm_bio_prison_cell
*alloc_prison_cell(struct cache
*cache
)
343 /* FIXME: change to use a local slab. */
344 return dm_bio_prison_alloc_cell(cache
->prison
, GFP_NOWAIT
);
347 static void free_prison_cell(struct cache
*cache
, struct dm_bio_prison_cell
*cell
)
349 dm_bio_prison_free_cell(cache
->prison
, cell
);
352 static int prealloc_data_structs(struct cache
*cache
, struct prealloc
*p
)
355 p
->mg
= mempool_alloc(cache
->migration_pool
, GFP_NOWAIT
);
361 p
->cell1
= alloc_prison_cell(cache
);
367 p
->cell2
= alloc_prison_cell(cache
);
375 static void prealloc_free_structs(struct cache
*cache
, struct prealloc
*p
)
378 free_prison_cell(cache
, p
->cell2
);
381 free_prison_cell(cache
, p
->cell1
);
384 mempool_free(p
->mg
, cache
->migration_pool
);
387 static struct dm_cache_migration
*prealloc_get_migration(struct prealloc
*p
)
389 struct dm_cache_migration
*mg
= p
->mg
;
398 * You must have a cell within the prealloc struct to return. If not this
399 * function will BUG() rather than returning NULL.
401 static struct dm_bio_prison_cell
*prealloc_get_cell(struct prealloc
*p
)
403 struct dm_bio_prison_cell
*r
= NULL
;
409 } else if (p
->cell2
) {
419 * You can't have more than two cells in a prealloc struct. BUG() will be
420 * called if you try and overfill.
422 static void prealloc_put_cell(struct prealloc
*p
, struct dm_bio_prison_cell
*cell
)
434 /*----------------------------------------------------------------*/
436 static void build_key(dm_oblock_t oblock
, struct dm_cell_key
*key
)
440 key
->block
= from_oblock(oblock
);
444 * The caller hands in a preallocated cell, and a free function for it.
445 * The cell will be freed if there's an error, or if it wasn't used because
446 * a cell with that key already exists.
448 typedef void (*cell_free_fn
)(void *context
, struct dm_bio_prison_cell
*cell
);
450 static int bio_detain(struct cache
*cache
, dm_oblock_t oblock
,
451 struct bio
*bio
, struct dm_bio_prison_cell
*cell_prealloc
,
452 cell_free_fn free_fn
, void *free_context
,
453 struct dm_bio_prison_cell
**cell_result
)
456 struct dm_cell_key key
;
458 build_key(oblock
, &key
);
459 r
= dm_bio_detain(cache
->prison
, &key
, bio
, cell_prealloc
, cell_result
);
461 free_fn(free_context
, cell_prealloc
);
466 static int get_cell(struct cache
*cache
,
468 struct prealloc
*structs
,
469 struct dm_bio_prison_cell
**cell_result
)
472 struct dm_cell_key key
;
473 struct dm_bio_prison_cell
*cell_prealloc
;
475 cell_prealloc
= prealloc_get_cell(structs
);
477 build_key(oblock
, &key
);
478 r
= dm_get_cell(cache
->prison
, &key
, cell_prealloc
, cell_result
);
480 prealloc_put_cell(structs
, cell_prealloc
);
485 /*----------------------------------------------------------------*/
487 static bool is_dirty(struct cache
*cache
, dm_cblock_t b
)
489 return test_bit(from_cblock(b
), cache
->dirty_bitset
);
492 static void set_dirty(struct cache
*cache
, dm_oblock_t oblock
, dm_cblock_t cblock
)
494 if (!test_and_set_bit(from_cblock(cblock
), cache
->dirty_bitset
)) {
495 atomic_inc(&cache
->nr_dirty
);
496 policy_set_dirty(cache
->policy
, oblock
);
500 static void clear_dirty(struct cache
*cache
, dm_oblock_t oblock
, dm_cblock_t cblock
)
502 if (test_and_clear_bit(from_cblock(cblock
), cache
->dirty_bitset
)) {
503 policy_clear_dirty(cache
->policy
, oblock
);
504 if (atomic_dec_return(&cache
->nr_dirty
) == 0)
505 dm_table_event(cache
->ti
->table
);
509 /*----------------------------------------------------------------*/
511 static bool block_size_is_power_of_two(struct cache
*cache
)
513 return cache
->sectors_per_block_shift
>= 0;
516 /* gcc on ARM generates spurious references to __udivdi3 and __umoddi3 */
517 #if defined(CONFIG_ARM) && __GNUC__ == 4 && __GNUC_MINOR__ <= 6
520 static dm_block_t
block_div(dm_block_t b
, uint32_t n
)
527 static void set_discard(struct cache
*cache
, dm_oblock_t b
)
531 atomic_inc(&cache
->stats
.discard_count
);
533 spin_lock_irqsave(&cache
->lock
, flags
);
534 set_bit(from_oblock(b
), cache
->discard_bitset
);
535 spin_unlock_irqrestore(&cache
->lock
, flags
);
538 static void clear_discard(struct cache
*cache
, dm_oblock_t b
)
542 spin_lock_irqsave(&cache
->lock
, flags
);
543 clear_bit(from_oblock(b
), cache
->discard_bitset
);
544 spin_unlock_irqrestore(&cache
->lock
, flags
);
547 static bool is_discarded(struct cache
*cache
, dm_oblock_t b
)
552 spin_lock_irqsave(&cache
->lock
, flags
);
553 r
= test_bit(from_oblock(b
), cache
->discard_bitset
);
554 spin_unlock_irqrestore(&cache
->lock
, flags
);
559 static bool is_discarded_oblock(struct cache
*cache
, dm_oblock_t b
)
564 spin_lock_irqsave(&cache
->lock
, flags
);
565 r
= test_bit(from_oblock(b
), cache
->discard_bitset
);
566 spin_unlock_irqrestore(&cache
->lock
, flags
);
571 /*----------------------------------------------------------------*/
573 static void load_stats(struct cache
*cache
)
575 struct dm_cache_statistics stats
;
577 dm_cache_metadata_get_stats(cache
->cmd
, &stats
);
578 atomic_set(&cache
->stats
.read_hit
, stats
.read_hits
);
579 atomic_set(&cache
->stats
.read_miss
, stats
.read_misses
);
580 atomic_set(&cache
->stats
.write_hit
, stats
.write_hits
);
581 atomic_set(&cache
->stats
.write_miss
, stats
.write_misses
);
584 static void save_stats(struct cache
*cache
)
586 struct dm_cache_statistics stats
;
588 stats
.read_hits
= atomic_read(&cache
->stats
.read_hit
);
589 stats
.read_misses
= atomic_read(&cache
->stats
.read_miss
);
590 stats
.write_hits
= atomic_read(&cache
->stats
.write_hit
);
591 stats
.write_misses
= atomic_read(&cache
->stats
.write_miss
);
593 dm_cache_metadata_set_stats(cache
->cmd
, &stats
);
596 /*----------------------------------------------------------------
598 *--------------------------------------------------------------*/
601 * If using writeback, leave out struct per_bio_data's writethrough fields.
603 #define PB_DATA_SIZE_WB (offsetof(struct per_bio_data, cache))
604 #define PB_DATA_SIZE_WT (sizeof(struct per_bio_data))
606 static bool writethrough_mode(struct cache_features
*f
)
608 return f
->io_mode
== CM_IO_WRITETHROUGH
;
611 static bool writeback_mode(struct cache_features
*f
)
613 return f
->io_mode
== CM_IO_WRITEBACK
;
616 static bool passthrough_mode(struct cache_features
*f
)
618 return f
->io_mode
== CM_IO_PASSTHROUGH
;
621 static size_t get_per_bio_data_size(struct cache
*cache
)
623 return writethrough_mode(&cache
->features
) ? PB_DATA_SIZE_WT
: PB_DATA_SIZE_WB
;
626 static struct per_bio_data
*get_per_bio_data(struct bio
*bio
, size_t data_size
)
628 struct per_bio_data
*pb
= dm_per_bio_data(bio
, data_size
);
633 static struct per_bio_data
*init_per_bio_data(struct bio
*bio
, size_t data_size
)
635 struct per_bio_data
*pb
= get_per_bio_data(bio
, data_size
);
638 pb
->req_nr
= dm_bio_get_target_bio_nr(bio
);
639 pb
->all_io_entry
= NULL
;
644 /*----------------------------------------------------------------
646 *--------------------------------------------------------------*/
647 static void remap_to_origin(struct cache
*cache
, struct bio
*bio
)
649 bio
->bi_bdev
= cache
->origin_dev
->bdev
;
652 static void remap_to_cache(struct cache
*cache
, struct bio
*bio
,
655 sector_t bi_sector
= bio
->bi_iter
.bi_sector
;
656 sector_t block
= from_cblock(cblock
);
658 bio
->bi_bdev
= cache
->cache_dev
->bdev
;
659 if (!block_size_is_power_of_two(cache
))
660 bio
->bi_iter
.bi_sector
=
661 (block
* cache
->sectors_per_block
) +
662 sector_div(bi_sector
, cache
->sectors_per_block
);
664 bio
->bi_iter
.bi_sector
=
665 (block
<< cache
->sectors_per_block_shift
) |
666 (bi_sector
& (cache
->sectors_per_block
- 1));
669 static void check_if_tick_bio_needed(struct cache
*cache
, struct bio
*bio
)
672 size_t pb_data_size
= get_per_bio_data_size(cache
);
673 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
675 spin_lock_irqsave(&cache
->lock
, flags
);
676 if (cache
->need_tick_bio
&&
677 !(bio
->bi_rw
& (REQ_FUA
| REQ_FLUSH
| REQ_DISCARD
))) {
679 cache
->need_tick_bio
= false;
681 spin_unlock_irqrestore(&cache
->lock
, flags
);
684 static void remap_to_origin_clear_discard(struct cache
*cache
, struct bio
*bio
,
687 check_if_tick_bio_needed(cache
, bio
);
688 remap_to_origin(cache
, bio
);
689 if (bio_data_dir(bio
) == WRITE
)
690 clear_discard(cache
, oblock
);
693 static void remap_to_cache_dirty(struct cache
*cache
, struct bio
*bio
,
694 dm_oblock_t oblock
, dm_cblock_t cblock
)
696 check_if_tick_bio_needed(cache
, bio
);
697 remap_to_cache(cache
, bio
, cblock
);
698 if (bio_data_dir(bio
) == WRITE
) {
699 set_dirty(cache
, oblock
, cblock
);
700 clear_discard(cache
, oblock
);
704 static dm_oblock_t
get_bio_block(struct cache
*cache
, struct bio
*bio
)
706 sector_t block_nr
= bio
->bi_iter
.bi_sector
;
708 if (!block_size_is_power_of_two(cache
))
709 (void) sector_div(block_nr
, cache
->sectors_per_block
);
711 block_nr
>>= cache
->sectors_per_block_shift
;
713 return to_oblock(block_nr
);
716 static int bio_triggers_commit(struct cache
*cache
, struct bio
*bio
)
718 return bio
->bi_rw
& (REQ_FLUSH
| REQ_FUA
);
721 static void issue(struct cache
*cache
, struct bio
*bio
)
725 if (!bio_triggers_commit(cache
, bio
)) {
726 generic_make_request(bio
);
731 * Batch together any bios that trigger commits and then issue a
732 * single commit for them in do_worker().
734 spin_lock_irqsave(&cache
->lock
, flags
);
735 cache
->commit_requested
= true;
736 bio_list_add(&cache
->deferred_flush_bios
, bio
);
737 spin_unlock_irqrestore(&cache
->lock
, flags
);
740 static void defer_writethrough_bio(struct cache
*cache
, struct bio
*bio
)
744 spin_lock_irqsave(&cache
->lock
, flags
);
745 bio_list_add(&cache
->deferred_writethrough_bios
, bio
);
746 spin_unlock_irqrestore(&cache
->lock
, flags
);
751 static void writethrough_endio(struct bio
*bio
, int err
)
753 struct per_bio_data
*pb
= get_per_bio_data(bio
, PB_DATA_SIZE_WT
);
755 dm_unhook_bio(&pb
->hook_info
, bio
);
762 dm_bio_restore(&pb
->bio_details
, bio
);
763 remap_to_cache(pb
->cache
, bio
, pb
->cblock
);
766 * We can't issue this bio directly, since we're in interrupt
767 * context. So it gets put on a bio list for processing by the
770 defer_writethrough_bio(pb
->cache
, bio
);
774 * When running in writethrough mode we need to send writes to clean blocks
775 * to both the cache and origin devices. In future we'd like to clone the
776 * bio and send them in parallel, but for now we're doing them in
777 * series as this is easier.
779 static void remap_to_origin_then_cache(struct cache
*cache
, struct bio
*bio
,
780 dm_oblock_t oblock
, dm_cblock_t cblock
)
782 struct per_bio_data
*pb
= get_per_bio_data(bio
, PB_DATA_SIZE_WT
);
786 dm_hook_bio(&pb
->hook_info
, bio
, writethrough_endio
, NULL
);
787 dm_bio_record(&pb
->bio_details
, bio
);
789 remap_to_origin_clear_discard(pb
->cache
, bio
, oblock
);
792 /*----------------------------------------------------------------
793 * Migration processing
795 * Migration covers moving data from the origin device to the cache, or
797 *--------------------------------------------------------------*/
798 static void free_migration(struct dm_cache_migration
*mg
)
800 mempool_free(mg
, mg
->cache
->migration_pool
);
803 static void inc_nr_migrations(struct cache
*cache
)
805 atomic_inc(&cache
->nr_migrations
);
808 static void dec_nr_migrations(struct cache
*cache
)
810 atomic_dec(&cache
->nr_migrations
);
813 * Wake the worker in case we're suspending the target.
815 wake_up(&cache
->migration_wait
);
818 static void __cell_defer(struct cache
*cache
, struct dm_bio_prison_cell
*cell
,
821 (holder
? dm_cell_release
: dm_cell_release_no_holder
)
822 (cache
->prison
, cell
, &cache
->deferred_bios
);
823 free_prison_cell(cache
, cell
);
826 static void cell_defer(struct cache
*cache
, struct dm_bio_prison_cell
*cell
,
831 spin_lock_irqsave(&cache
->lock
, flags
);
832 __cell_defer(cache
, cell
, holder
);
833 spin_unlock_irqrestore(&cache
->lock
, flags
);
838 static void cleanup_migration(struct dm_cache_migration
*mg
)
840 struct cache
*cache
= mg
->cache
;
842 dec_nr_migrations(cache
);
845 static void migration_failure(struct dm_cache_migration
*mg
)
847 struct cache
*cache
= mg
->cache
;
850 DMWARN_LIMIT("writeback failed; couldn't copy block");
851 set_dirty(cache
, mg
->old_oblock
, mg
->cblock
);
852 cell_defer(cache
, mg
->old_ocell
, false);
854 } else if (mg
->demote
) {
855 DMWARN_LIMIT("demotion failed; couldn't copy block");
856 policy_force_mapping(cache
->policy
, mg
->new_oblock
, mg
->old_oblock
);
858 cell_defer(cache
, mg
->old_ocell
, mg
->promote
? false : true);
860 cell_defer(cache
, mg
->new_ocell
, true);
862 DMWARN_LIMIT("promotion failed; couldn't copy block");
863 policy_remove_mapping(cache
->policy
, mg
->new_oblock
);
864 cell_defer(cache
, mg
->new_ocell
, true);
867 cleanup_migration(mg
);
870 static void migration_success_pre_commit(struct dm_cache_migration
*mg
)
873 struct cache
*cache
= mg
->cache
;
876 cell_defer(cache
, mg
->old_ocell
, false);
877 clear_dirty(cache
, mg
->old_oblock
, mg
->cblock
);
878 cleanup_migration(mg
);
881 } else if (mg
->demote
) {
882 if (dm_cache_remove_mapping(cache
->cmd
, mg
->cblock
)) {
883 DMWARN_LIMIT("demotion failed; couldn't update on disk metadata");
884 policy_force_mapping(cache
->policy
, mg
->new_oblock
,
887 cell_defer(cache
, mg
->new_ocell
, true);
888 cleanup_migration(mg
);
892 if (dm_cache_insert_mapping(cache
->cmd
, mg
->cblock
, mg
->new_oblock
)) {
893 DMWARN_LIMIT("promotion failed; couldn't update on disk metadata");
894 policy_remove_mapping(cache
->policy
, mg
->new_oblock
);
895 cleanup_migration(mg
);
900 spin_lock_irqsave(&cache
->lock
, flags
);
901 list_add_tail(&mg
->list
, &cache
->need_commit_migrations
);
902 cache
->commit_requested
= true;
903 spin_unlock_irqrestore(&cache
->lock
, flags
);
906 static void migration_success_post_commit(struct dm_cache_migration
*mg
)
909 struct cache
*cache
= mg
->cache
;
912 DMWARN("writeback unexpectedly triggered commit");
915 } else if (mg
->demote
) {
916 cell_defer(cache
, mg
->old_ocell
, mg
->promote
? false : true);
921 spin_lock_irqsave(&cache
->lock
, flags
);
922 list_add_tail(&mg
->list
, &cache
->quiesced_migrations
);
923 spin_unlock_irqrestore(&cache
->lock
, flags
);
927 policy_remove_mapping(cache
->policy
, mg
->old_oblock
);
928 cleanup_migration(mg
);
932 if (mg
->requeue_holder
)
933 cell_defer(cache
, mg
->new_ocell
, true);
935 bio_endio(mg
->new_ocell
->holder
, 0);
936 cell_defer(cache
, mg
->new_ocell
, false);
938 clear_dirty(cache
, mg
->new_oblock
, mg
->cblock
);
939 cleanup_migration(mg
);
943 static void copy_complete(int read_err
, unsigned long write_err
, void *context
)
946 struct dm_cache_migration
*mg
= (struct dm_cache_migration
*) context
;
947 struct cache
*cache
= mg
->cache
;
949 if (read_err
|| write_err
)
952 spin_lock_irqsave(&cache
->lock
, flags
);
953 list_add_tail(&mg
->list
, &cache
->completed_migrations
);
954 spin_unlock_irqrestore(&cache
->lock
, flags
);
959 static void issue_copy_real(struct dm_cache_migration
*mg
)
962 struct dm_io_region o_region
, c_region
;
963 struct cache
*cache
= mg
->cache
;
964 sector_t cblock
= from_cblock(mg
->cblock
);
966 o_region
.bdev
= cache
->origin_dev
->bdev
;
967 o_region
.count
= cache
->sectors_per_block
;
969 c_region
.bdev
= cache
->cache_dev
->bdev
;
970 c_region
.sector
= cblock
* cache
->sectors_per_block
;
971 c_region
.count
= cache
->sectors_per_block
;
973 if (mg
->writeback
|| mg
->demote
) {
975 o_region
.sector
= from_oblock(mg
->old_oblock
) * cache
->sectors_per_block
;
976 r
= dm_kcopyd_copy(cache
->copier
, &c_region
, 1, &o_region
, 0, copy_complete
, mg
);
979 o_region
.sector
= from_oblock(mg
->new_oblock
) * cache
->sectors_per_block
;
980 r
= dm_kcopyd_copy(cache
->copier
, &o_region
, 1, &c_region
, 0, copy_complete
, mg
);
984 DMERR_LIMIT("issuing migration failed");
985 migration_failure(mg
);
989 static void overwrite_endio(struct bio
*bio
, int err
)
991 struct dm_cache_migration
*mg
= bio
->bi_private
;
992 struct cache
*cache
= mg
->cache
;
993 size_t pb_data_size
= get_per_bio_data_size(cache
);
994 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
997 dm_unhook_bio(&pb
->hook_info
, bio
);
1002 mg
->requeue_holder
= false;
1004 spin_lock_irqsave(&cache
->lock
, flags
);
1005 list_add_tail(&mg
->list
, &cache
->completed_migrations
);
1006 spin_unlock_irqrestore(&cache
->lock
, flags
);
1011 static void issue_overwrite(struct dm_cache_migration
*mg
, struct bio
*bio
)
1013 size_t pb_data_size
= get_per_bio_data_size(mg
->cache
);
1014 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
1016 dm_hook_bio(&pb
->hook_info
, bio
, overwrite_endio
, mg
);
1017 remap_to_cache_dirty(mg
->cache
, bio
, mg
->new_oblock
, mg
->cblock
);
1018 generic_make_request(bio
);
1021 static bool bio_writes_complete_block(struct cache
*cache
, struct bio
*bio
)
1023 return (bio_data_dir(bio
) == WRITE
) &&
1024 (bio
->bi_iter
.bi_size
== (cache
->sectors_per_block
<< SECTOR_SHIFT
));
1027 static void avoid_copy(struct dm_cache_migration
*mg
)
1029 atomic_inc(&mg
->cache
->stats
.copies_avoided
);
1030 migration_success_pre_commit(mg
);
1033 static void issue_copy(struct dm_cache_migration
*mg
)
1036 struct cache
*cache
= mg
->cache
;
1038 if (mg
->writeback
|| mg
->demote
)
1039 avoid
= !is_dirty(cache
, mg
->cblock
) ||
1040 is_discarded_oblock(cache
, mg
->old_oblock
);
1042 struct bio
*bio
= mg
->new_ocell
->holder
;
1044 avoid
= is_discarded_oblock(cache
, mg
->new_oblock
);
1046 if (!avoid
&& bio_writes_complete_block(cache
, bio
)) {
1047 issue_overwrite(mg
, bio
);
1052 avoid
? avoid_copy(mg
) : issue_copy_real(mg
);
1055 static void complete_migration(struct dm_cache_migration
*mg
)
1058 migration_failure(mg
);
1060 migration_success_pre_commit(mg
);
1063 static void process_migrations(struct cache
*cache
, struct list_head
*head
,
1064 void (*fn
)(struct dm_cache_migration
*))
1066 unsigned long flags
;
1067 struct list_head list
;
1068 struct dm_cache_migration
*mg
, *tmp
;
1070 INIT_LIST_HEAD(&list
);
1071 spin_lock_irqsave(&cache
->lock
, flags
);
1072 list_splice_init(head
, &list
);
1073 spin_unlock_irqrestore(&cache
->lock
, flags
);
1075 list_for_each_entry_safe(mg
, tmp
, &list
, list
)
1079 static void __queue_quiesced_migration(struct dm_cache_migration
*mg
)
1081 list_add_tail(&mg
->list
, &mg
->cache
->quiesced_migrations
);
1084 static void queue_quiesced_migration(struct dm_cache_migration
*mg
)
1086 unsigned long flags
;
1087 struct cache
*cache
= mg
->cache
;
1089 spin_lock_irqsave(&cache
->lock
, flags
);
1090 __queue_quiesced_migration(mg
);
1091 spin_unlock_irqrestore(&cache
->lock
, flags
);
1096 static void queue_quiesced_migrations(struct cache
*cache
, struct list_head
*work
)
1098 unsigned long flags
;
1099 struct dm_cache_migration
*mg
, *tmp
;
1101 spin_lock_irqsave(&cache
->lock
, flags
);
1102 list_for_each_entry_safe(mg
, tmp
, work
, list
)
1103 __queue_quiesced_migration(mg
);
1104 spin_unlock_irqrestore(&cache
->lock
, flags
);
1109 static void check_for_quiesced_migrations(struct cache
*cache
,
1110 struct per_bio_data
*pb
)
1112 struct list_head work
;
1114 if (!pb
->all_io_entry
)
1117 INIT_LIST_HEAD(&work
);
1118 if (pb
->all_io_entry
)
1119 dm_deferred_entry_dec(pb
->all_io_entry
, &work
);
1121 if (!list_empty(&work
))
1122 queue_quiesced_migrations(cache
, &work
);
1125 static void quiesce_migration(struct dm_cache_migration
*mg
)
1127 if (!dm_deferred_set_add_work(mg
->cache
->all_io_ds
, &mg
->list
))
1128 queue_quiesced_migration(mg
);
1131 static void promote(struct cache
*cache
, struct prealloc
*structs
,
1132 dm_oblock_t oblock
, dm_cblock_t cblock
,
1133 struct dm_bio_prison_cell
*cell
)
1135 struct dm_cache_migration
*mg
= prealloc_get_migration(structs
);
1138 mg
->writeback
= false;
1141 mg
->requeue_holder
= true;
1142 mg
->invalidate
= false;
1144 mg
->new_oblock
= oblock
;
1145 mg
->cblock
= cblock
;
1146 mg
->old_ocell
= NULL
;
1147 mg
->new_ocell
= cell
;
1148 mg
->start_jiffies
= jiffies
;
1150 inc_nr_migrations(cache
);
1151 quiesce_migration(mg
);
1154 static void writeback(struct cache
*cache
, struct prealloc
*structs
,
1155 dm_oblock_t oblock
, dm_cblock_t cblock
,
1156 struct dm_bio_prison_cell
*cell
)
1158 struct dm_cache_migration
*mg
= prealloc_get_migration(structs
);
1161 mg
->writeback
= true;
1163 mg
->promote
= false;
1164 mg
->requeue_holder
= true;
1165 mg
->invalidate
= false;
1167 mg
->old_oblock
= oblock
;
1168 mg
->cblock
= cblock
;
1169 mg
->old_ocell
= cell
;
1170 mg
->new_ocell
= NULL
;
1171 mg
->start_jiffies
= jiffies
;
1173 inc_nr_migrations(cache
);
1174 quiesce_migration(mg
);
1177 static void demote_then_promote(struct cache
*cache
, struct prealloc
*structs
,
1178 dm_oblock_t old_oblock
, dm_oblock_t new_oblock
,
1180 struct dm_bio_prison_cell
*old_ocell
,
1181 struct dm_bio_prison_cell
*new_ocell
)
1183 struct dm_cache_migration
*mg
= prealloc_get_migration(structs
);
1186 mg
->writeback
= false;
1189 mg
->requeue_holder
= true;
1190 mg
->invalidate
= false;
1192 mg
->old_oblock
= old_oblock
;
1193 mg
->new_oblock
= new_oblock
;
1194 mg
->cblock
= cblock
;
1195 mg
->old_ocell
= old_ocell
;
1196 mg
->new_ocell
= new_ocell
;
1197 mg
->start_jiffies
= jiffies
;
1199 inc_nr_migrations(cache
);
1200 quiesce_migration(mg
);
1204 * Invalidate a cache entry. No writeback occurs; any changes in the cache
1205 * block are thrown away.
1207 static void invalidate(struct cache
*cache
, struct prealloc
*structs
,
1208 dm_oblock_t oblock
, dm_cblock_t cblock
,
1209 struct dm_bio_prison_cell
*cell
)
1211 struct dm_cache_migration
*mg
= prealloc_get_migration(structs
);
1214 mg
->writeback
= false;
1216 mg
->promote
= false;
1217 mg
->requeue_holder
= true;
1218 mg
->invalidate
= true;
1220 mg
->old_oblock
= oblock
;
1221 mg
->cblock
= cblock
;
1222 mg
->old_ocell
= cell
;
1223 mg
->new_ocell
= NULL
;
1224 mg
->start_jiffies
= jiffies
;
1226 inc_nr_migrations(cache
);
1227 quiesce_migration(mg
);
1230 /*----------------------------------------------------------------
1232 *--------------------------------------------------------------*/
1233 static void defer_bio(struct cache
*cache
, struct bio
*bio
)
1235 unsigned long flags
;
1237 spin_lock_irqsave(&cache
->lock
, flags
);
1238 bio_list_add(&cache
->deferred_bios
, bio
);
1239 spin_unlock_irqrestore(&cache
->lock
, flags
);
1244 static void process_flush_bio(struct cache
*cache
, struct bio
*bio
)
1246 size_t pb_data_size
= get_per_bio_data_size(cache
);
1247 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
1249 BUG_ON(bio
->bi_iter
.bi_size
);
1251 remap_to_origin(cache
, bio
);
1253 remap_to_cache(cache
, bio
, 0);
1259 * People generally discard large parts of a device, eg, the whole device
1260 * when formatting. Splitting these large discards up into cache block
1261 * sized ios and then quiescing (always neccessary for discard) takes too
1264 * We keep it simple, and allow any size of discard to come in, and just
1265 * mark off blocks on the discard bitset. No passdown occurs!
1267 * To implement passdown we need to change the bio_prison such that a cell
1268 * can have a key that spans many blocks.
1270 static void process_discard_bio(struct cache
*cache
, struct bio
*bio
)
1272 dm_block_t start_block
= dm_sector_div_up(bio
->bi_iter
.bi_sector
,
1273 cache
->sectors_per_block
);
1274 dm_block_t end_block
= bio_end_sector(bio
);
1277 end_block
= block_div(end_block
, cache
->sectors_per_block
);
1279 for (b
= start_block
; b
< end_block
; b
++)
1280 set_discard(cache
, to_oblock(b
));
1285 static bool spare_migration_bandwidth(struct cache
*cache
)
1287 sector_t current_volume
= (atomic_read(&cache
->nr_migrations
) + 1) *
1288 cache
->sectors_per_block
;
1289 return current_volume
< cache
->migration_threshold
;
1292 static void inc_hit_counter(struct cache
*cache
, struct bio
*bio
)
1294 atomic_inc(bio_data_dir(bio
) == READ
?
1295 &cache
->stats
.read_hit
: &cache
->stats
.write_hit
);
1298 static void inc_miss_counter(struct cache
*cache
, struct bio
*bio
)
1300 atomic_inc(bio_data_dir(bio
) == READ
?
1301 &cache
->stats
.read_miss
: &cache
->stats
.write_miss
);
1304 static void issue_cache_bio(struct cache
*cache
, struct bio
*bio
,
1305 struct per_bio_data
*pb
,
1306 dm_oblock_t oblock
, dm_cblock_t cblock
)
1308 pb
->all_io_entry
= dm_deferred_entry_inc(cache
->all_io_ds
);
1309 remap_to_cache_dirty(cache
, bio
, oblock
, cblock
);
1313 static void process_bio(struct cache
*cache
, struct prealloc
*structs
,
1317 bool release_cell
= true;
1318 dm_oblock_t block
= get_bio_block(cache
, bio
);
1319 struct dm_bio_prison_cell
*cell_prealloc
, *old_ocell
, *new_ocell
;
1320 struct policy_result lookup_result
;
1321 size_t pb_data_size
= get_per_bio_data_size(cache
);
1322 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
1323 bool discarded_block
= is_discarded_oblock(cache
, block
);
1324 bool passthrough
= passthrough_mode(&cache
->features
);
1325 bool can_migrate
= !passthrough
&& (discarded_block
|| spare_migration_bandwidth(cache
));
1328 * Check to see if that block is currently migrating.
1330 cell_prealloc
= prealloc_get_cell(structs
);
1331 r
= bio_detain(cache
, block
, bio
, cell_prealloc
,
1332 (cell_free_fn
) prealloc_put_cell
,
1333 structs
, &new_ocell
);
1337 r
= policy_map(cache
->policy
, block
, true, can_migrate
, discarded_block
,
1338 bio
, &lookup_result
);
1340 if (r
== -EWOULDBLOCK
)
1341 /* migration has been denied */
1342 lookup_result
.op
= POLICY_MISS
;
1344 switch (lookup_result
.op
) {
1347 inc_miss_counter(cache
, bio
);
1350 * Passthrough always maps to the origin,
1351 * invalidating any cache blocks that are written
1355 if (bio_data_dir(bio
) == WRITE
) {
1356 atomic_inc(&cache
->stats
.demotion
);
1357 invalidate(cache
, structs
, block
, lookup_result
.cblock
, new_ocell
);
1358 release_cell
= false;
1361 /* FIXME: factor out issue_origin() */
1362 pb
->all_io_entry
= dm_deferred_entry_inc(cache
->all_io_ds
);
1363 remap_to_origin_clear_discard(cache
, bio
, block
);
1367 inc_hit_counter(cache
, bio
);
1369 if (bio_data_dir(bio
) == WRITE
&&
1370 writethrough_mode(&cache
->features
) &&
1371 !is_dirty(cache
, lookup_result
.cblock
)) {
1372 pb
->all_io_entry
= dm_deferred_entry_inc(cache
->all_io_ds
);
1373 remap_to_origin_then_cache(cache
, bio
, block
, lookup_result
.cblock
);
1376 issue_cache_bio(cache
, bio
, pb
, block
, lookup_result
.cblock
);
1382 inc_miss_counter(cache
, bio
);
1383 pb
->all_io_entry
= dm_deferred_entry_inc(cache
->all_io_ds
);
1384 remap_to_origin_clear_discard(cache
, bio
, block
);
1389 atomic_inc(&cache
->stats
.promotion
);
1390 promote(cache
, structs
, block
, lookup_result
.cblock
, new_ocell
);
1391 release_cell
= false;
1394 case POLICY_REPLACE
:
1395 cell_prealloc
= prealloc_get_cell(structs
);
1396 r
= bio_detain(cache
, lookup_result
.old_oblock
, bio
, cell_prealloc
,
1397 (cell_free_fn
) prealloc_put_cell
,
1398 structs
, &old_ocell
);
1401 * We have to be careful to avoid lock inversion of
1402 * the cells. So we back off, and wait for the
1403 * old_ocell to become free.
1405 policy_force_mapping(cache
->policy
, block
,
1406 lookup_result
.old_oblock
);
1407 atomic_inc(&cache
->stats
.cache_cell_clash
);
1410 atomic_inc(&cache
->stats
.demotion
);
1411 atomic_inc(&cache
->stats
.promotion
);
1413 demote_then_promote(cache
, structs
, lookup_result
.old_oblock
,
1414 block
, lookup_result
.cblock
,
1415 old_ocell
, new_ocell
);
1416 release_cell
= false;
1420 DMERR_LIMIT("%s: erroring bio, unknown policy op: %u", __func__
,
1421 (unsigned) lookup_result
.op
);
1426 cell_defer(cache
, new_ocell
, false);
1429 static int need_commit_due_to_time(struct cache
*cache
)
1431 return jiffies
< cache
->last_commit_jiffies
||
1432 jiffies
> cache
->last_commit_jiffies
+ COMMIT_PERIOD
;
1435 static int commit_if_needed(struct cache
*cache
)
1439 if ((cache
->commit_requested
|| need_commit_due_to_time(cache
)) &&
1440 dm_cache_changed_this_transaction(cache
->cmd
)) {
1441 atomic_inc(&cache
->stats
.commit_count
);
1442 cache
->commit_requested
= false;
1443 r
= dm_cache_commit(cache
->cmd
, false);
1444 cache
->last_commit_jiffies
= jiffies
;
1450 static void process_deferred_bios(struct cache
*cache
)
1452 unsigned long flags
;
1453 struct bio_list bios
;
1455 struct prealloc structs
;
1457 memset(&structs
, 0, sizeof(structs
));
1458 bio_list_init(&bios
);
1460 spin_lock_irqsave(&cache
->lock
, flags
);
1461 bio_list_merge(&bios
, &cache
->deferred_bios
);
1462 bio_list_init(&cache
->deferred_bios
);
1463 spin_unlock_irqrestore(&cache
->lock
, flags
);
1465 while (!bio_list_empty(&bios
)) {
1467 * If we've got no free migration structs, and processing
1468 * this bio might require one, we pause until there are some
1469 * prepared mappings to process.
1471 if (prealloc_data_structs(cache
, &structs
)) {
1472 spin_lock_irqsave(&cache
->lock
, flags
);
1473 bio_list_merge(&cache
->deferred_bios
, &bios
);
1474 spin_unlock_irqrestore(&cache
->lock
, flags
);
1478 bio
= bio_list_pop(&bios
);
1480 if (bio
->bi_rw
& REQ_FLUSH
)
1481 process_flush_bio(cache
, bio
);
1482 else if (bio
->bi_rw
& REQ_DISCARD
)
1483 process_discard_bio(cache
, bio
);
1485 process_bio(cache
, &structs
, bio
);
1488 prealloc_free_structs(cache
, &structs
);
1491 static void process_deferred_flush_bios(struct cache
*cache
, bool submit_bios
)
1493 unsigned long flags
;
1494 struct bio_list bios
;
1497 bio_list_init(&bios
);
1499 spin_lock_irqsave(&cache
->lock
, flags
);
1500 bio_list_merge(&bios
, &cache
->deferred_flush_bios
);
1501 bio_list_init(&cache
->deferred_flush_bios
);
1502 spin_unlock_irqrestore(&cache
->lock
, flags
);
1504 while ((bio
= bio_list_pop(&bios
)))
1505 submit_bios
? generic_make_request(bio
) : bio_io_error(bio
);
1508 static void process_deferred_writethrough_bios(struct cache
*cache
)
1510 unsigned long flags
;
1511 struct bio_list bios
;
1514 bio_list_init(&bios
);
1516 spin_lock_irqsave(&cache
->lock
, flags
);
1517 bio_list_merge(&bios
, &cache
->deferred_writethrough_bios
);
1518 bio_list_init(&cache
->deferred_writethrough_bios
);
1519 spin_unlock_irqrestore(&cache
->lock
, flags
);
1521 while ((bio
= bio_list_pop(&bios
)))
1522 generic_make_request(bio
);
1525 static void writeback_some_dirty_blocks(struct cache
*cache
)
1530 struct prealloc structs
;
1531 struct dm_bio_prison_cell
*old_ocell
;
1533 memset(&structs
, 0, sizeof(structs
));
1535 while (spare_migration_bandwidth(cache
)) {
1536 if (prealloc_data_structs(cache
, &structs
))
1539 r
= policy_writeback_work(cache
->policy
, &oblock
, &cblock
);
1543 r
= get_cell(cache
, oblock
, &structs
, &old_ocell
);
1545 policy_set_dirty(cache
->policy
, oblock
);
1549 writeback(cache
, &structs
, oblock
, cblock
, old_ocell
);
1552 prealloc_free_structs(cache
, &structs
);
1555 /*----------------------------------------------------------------
1557 * Dropping something from the cache *without* writing back.
1558 *--------------------------------------------------------------*/
1560 static void process_invalidation_request(struct cache
*cache
, struct invalidation_request
*req
)
1563 uint64_t begin
= from_cblock(req
->cblocks
->begin
);
1564 uint64_t end
= from_cblock(req
->cblocks
->end
);
1566 while (begin
!= end
) {
1567 r
= policy_remove_cblock(cache
->policy
, to_cblock(begin
));
1569 r
= dm_cache_remove_mapping(cache
->cmd
, to_cblock(begin
));
1573 } else if (r
== -ENODATA
) {
1574 /* harmless, already unmapped */
1578 DMERR("policy_remove_cblock failed");
1585 cache
->commit_requested
= true;
1588 atomic_set(&req
->complete
, 1);
1590 wake_up(&req
->result_wait
);
1593 static void process_invalidation_requests(struct cache
*cache
)
1595 struct list_head list
;
1596 struct invalidation_request
*req
, *tmp
;
1598 INIT_LIST_HEAD(&list
);
1599 spin_lock(&cache
->invalidation_lock
);
1600 list_splice_init(&cache
->invalidation_requests
, &list
);
1601 spin_unlock(&cache
->invalidation_lock
);
1603 list_for_each_entry_safe (req
, tmp
, &list
, list
)
1604 process_invalidation_request(cache
, req
);
1607 /*----------------------------------------------------------------
1609 *--------------------------------------------------------------*/
1610 static bool is_quiescing(struct cache
*cache
)
1612 return atomic_read(&cache
->quiescing
);
1615 static void ack_quiescing(struct cache
*cache
)
1617 if (is_quiescing(cache
)) {
1618 atomic_inc(&cache
->quiescing_ack
);
1619 wake_up(&cache
->quiescing_wait
);
1623 static void wait_for_quiescing_ack(struct cache
*cache
)
1625 wait_event(cache
->quiescing_wait
, atomic_read(&cache
->quiescing_ack
));
1628 static void start_quiescing(struct cache
*cache
)
1630 atomic_inc(&cache
->quiescing
);
1631 wait_for_quiescing_ack(cache
);
1634 static void stop_quiescing(struct cache
*cache
)
1636 atomic_set(&cache
->quiescing
, 0);
1637 atomic_set(&cache
->quiescing_ack
, 0);
1640 static void wait_for_migrations(struct cache
*cache
)
1642 wait_event(cache
->migration_wait
, !atomic_read(&cache
->nr_migrations
));
1645 static void stop_worker(struct cache
*cache
)
1647 cancel_delayed_work(&cache
->waker
);
1648 flush_workqueue(cache
->wq
);
1651 static void requeue_deferred_io(struct cache
*cache
)
1654 struct bio_list bios
;
1656 bio_list_init(&bios
);
1657 bio_list_merge(&bios
, &cache
->deferred_bios
);
1658 bio_list_init(&cache
->deferred_bios
);
1660 while ((bio
= bio_list_pop(&bios
)))
1661 bio_endio(bio
, DM_ENDIO_REQUEUE
);
1664 static int more_work(struct cache
*cache
)
1666 if (is_quiescing(cache
))
1667 return !list_empty(&cache
->quiesced_migrations
) ||
1668 !list_empty(&cache
->completed_migrations
) ||
1669 !list_empty(&cache
->need_commit_migrations
);
1671 return !bio_list_empty(&cache
->deferred_bios
) ||
1672 !bio_list_empty(&cache
->deferred_flush_bios
) ||
1673 !bio_list_empty(&cache
->deferred_writethrough_bios
) ||
1674 !list_empty(&cache
->quiesced_migrations
) ||
1675 !list_empty(&cache
->completed_migrations
) ||
1676 !list_empty(&cache
->need_commit_migrations
) ||
1680 static void do_worker(struct work_struct
*ws
)
1682 struct cache
*cache
= container_of(ws
, struct cache
, worker
);
1685 if (!is_quiescing(cache
)) {
1686 writeback_some_dirty_blocks(cache
);
1687 process_deferred_writethrough_bios(cache
);
1688 process_deferred_bios(cache
);
1689 process_invalidation_requests(cache
);
1692 process_migrations(cache
, &cache
->quiesced_migrations
, issue_copy
);
1693 process_migrations(cache
, &cache
->completed_migrations
, complete_migration
);
1695 if (commit_if_needed(cache
)) {
1696 process_deferred_flush_bios(cache
, false);
1699 * FIXME: rollback metadata or just go into a
1700 * failure mode and error everything
1703 process_deferred_flush_bios(cache
, true);
1704 process_migrations(cache
, &cache
->need_commit_migrations
,
1705 migration_success_post_commit
);
1708 ack_quiescing(cache
);
1710 } while (more_work(cache
));
1714 * We want to commit periodically so that not too much
1715 * unwritten metadata builds up.
1717 static void do_waker(struct work_struct
*ws
)
1719 struct cache
*cache
= container_of(to_delayed_work(ws
), struct cache
, waker
);
1720 policy_tick(cache
->policy
);
1722 queue_delayed_work(cache
->wq
, &cache
->waker
, COMMIT_PERIOD
);
1725 /*----------------------------------------------------------------*/
1727 static int is_congested(struct dm_dev
*dev
, int bdi_bits
)
1729 struct request_queue
*q
= bdev_get_queue(dev
->bdev
);
1730 return bdi_congested(&q
->backing_dev_info
, bdi_bits
);
1733 static int cache_is_congested(struct dm_target_callbacks
*cb
, int bdi_bits
)
1735 struct cache
*cache
= container_of(cb
, struct cache
, callbacks
);
1737 return is_congested(cache
->origin_dev
, bdi_bits
) ||
1738 is_congested(cache
->cache_dev
, bdi_bits
);
1741 /*----------------------------------------------------------------
1743 *--------------------------------------------------------------*/
1746 * This function gets called on the error paths of the constructor, so we
1747 * have to cope with a partially initialised struct.
1749 static void destroy(struct cache
*cache
)
1753 if (cache
->next_migration
)
1754 mempool_free(cache
->next_migration
, cache
->migration_pool
);
1756 if (cache
->migration_pool
)
1757 mempool_destroy(cache
->migration_pool
);
1759 if (cache
->all_io_ds
)
1760 dm_deferred_set_destroy(cache
->all_io_ds
);
1763 dm_bio_prison_destroy(cache
->prison
);
1766 destroy_workqueue(cache
->wq
);
1768 if (cache
->dirty_bitset
)
1769 free_bitset(cache
->dirty_bitset
);
1771 if (cache
->discard_bitset
)
1772 free_bitset(cache
->discard_bitset
);
1775 dm_kcopyd_client_destroy(cache
->copier
);
1778 dm_cache_metadata_close(cache
->cmd
);
1780 if (cache
->metadata_dev
)
1781 dm_put_device(cache
->ti
, cache
->metadata_dev
);
1783 if (cache
->origin_dev
)
1784 dm_put_device(cache
->ti
, cache
->origin_dev
);
1786 if (cache
->cache_dev
)
1787 dm_put_device(cache
->ti
, cache
->cache_dev
);
1790 dm_cache_policy_destroy(cache
->policy
);
1792 for (i
= 0; i
< cache
->nr_ctr_args
; i
++)
1793 kfree(cache
->ctr_args
[i
]);
1794 kfree(cache
->ctr_args
);
1799 static void cache_dtr(struct dm_target
*ti
)
1801 struct cache
*cache
= ti
->private;
1806 static sector_t
get_dev_size(struct dm_dev
*dev
)
1808 return i_size_read(dev
->bdev
->bd_inode
) >> SECTOR_SHIFT
;
1811 /*----------------------------------------------------------------*/
1814 * Construct a cache device mapping.
1816 * cache <metadata dev> <cache dev> <origin dev> <block size>
1817 * <#feature args> [<feature arg>]*
1818 * <policy> <#policy args> [<policy arg>]*
1820 * metadata dev : fast device holding the persistent metadata
1821 * cache dev : fast device holding cached data blocks
1822 * origin dev : slow device holding original data blocks
1823 * block size : cache unit size in sectors
1825 * #feature args : number of feature arguments passed
1826 * feature args : writethrough. (The default is writeback.)
1828 * policy : the replacement policy to use
1829 * #policy args : an even number of policy arguments corresponding
1830 * to key/value pairs passed to the policy
1831 * policy args : key/value pairs passed to the policy
1832 * E.g. 'sequential_threshold 1024'
1833 * See cache-policies.txt for details.
1835 * Optional feature arguments are:
1836 * writethrough : write through caching that prohibits cache block
1837 * content from being different from origin block content.
1838 * Without this argument, the default behaviour is to write
1839 * back cache block contents later for performance reasons,
1840 * so they may differ from the corresponding origin blocks.
1843 struct dm_target
*ti
;
1845 struct dm_dev
*metadata_dev
;
1847 struct dm_dev
*cache_dev
;
1848 sector_t cache_sectors
;
1850 struct dm_dev
*origin_dev
;
1851 sector_t origin_sectors
;
1853 uint32_t block_size
;
1855 const char *policy_name
;
1857 const char **policy_argv
;
1859 struct cache_features features
;
1862 static void destroy_cache_args(struct cache_args
*ca
)
1864 if (ca
->metadata_dev
)
1865 dm_put_device(ca
->ti
, ca
->metadata_dev
);
1868 dm_put_device(ca
->ti
, ca
->cache_dev
);
1871 dm_put_device(ca
->ti
, ca
->origin_dev
);
1876 static bool at_least_one_arg(struct dm_arg_set
*as
, char **error
)
1879 *error
= "Insufficient args";
1886 static int parse_metadata_dev(struct cache_args
*ca
, struct dm_arg_set
*as
,
1890 sector_t metadata_dev_size
;
1891 char b
[BDEVNAME_SIZE
];
1893 if (!at_least_one_arg(as
, error
))
1896 r
= dm_get_device(ca
->ti
, dm_shift_arg(as
), FMODE_READ
| FMODE_WRITE
,
1899 *error
= "Error opening metadata device";
1903 metadata_dev_size
= get_dev_size(ca
->metadata_dev
);
1904 if (metadata_dev_size
> DM_CACHE_METADATA_MAX_SECTORS_WARNING
)
1905 DMWARN("Metadata device %s is larger than %u sectors: excess space will not be used.",
1906 bdevname(ca
->metadata_dev
->bdev
, b
), THIN_METADATA_MAX_SECTORS
);
1911 static int parse_cache_dev(struct cache_args
*ca
, struct dm_arg_set
*as
,
1916 if (!at_least_one_arg(as
, error
))
1919 r
= dm_get_device(ca
->ti
, dm_shift_arg(as
), FMODE_READ
| FMODE_WRITE
,
1922 *error
= "Error opening cache device";
1925 ca
->cache_sectors
= get_dev_size(ca
->cache_dev
);
1930 static int parse_origin_dev(struct cache_args
*ca
, struct dm_arg_set
*as
,
1935 if (!at_least_one_arg(as
, error
))
1938 r
= dm_get_device(ca
->ti
, dm_shift_arg(as
), FMODE_READ
| FMODE_WRITE
,
1941 *error
= "Error opening origin device";
1945 ca
->origin_sectors
= get_dev_size(ca
->origin_dev
);
1946 if (ca
->ti
->len
> ca
->origin_sectors
) {
1947 *error
= "Device size larger than cached device";
1954 static int parse_block_size(struct cache_args
*ca
, struct dm_arg_set
*as
,
1957 unsigned long block_size
;
1959 if (!at_least_one_arg(as
, error
))
1962 if (kstrtoul(dm_shift_arg(as
), 10, &block_size
) || !block_size
||
1963 block_size
< DATA_DEV_BLOCK_SIZE_MIN_SECTORS
||
1964 block_size
> DATA_DEV_BLOCK_SIZE_MAX_SECTORS
||
1965 block_size
& (DATA_DEV_BLOCK_SIZE_MIN_SECTORS
- 1)) {
1966 *error
= "Invalid data block size";
1970 if (block_size
> ca
->cache_sectors
) {
1971 *error
= "Data block size is larger than the cache device";
1975 ca
->block_size
= block_size
;
1980 static void init_features(struct cache_features
*cf
)
1982 cf
->mode
= CM_WRITE
;
1983 cf
->io_mode
= CM_IO_WRITEBACK
;
1986 static int parse_features(struct cache_args
*ca
, struct dm_arg_set
*as
,
1989 static struct dm_arg _args
[] = {
1990 {0, 1, "Invalid number of cache feature arguments"},
1996 struct cache_features
*cf
= &ca
->features
;
2000 r
= dm_read_arg_group(_args
, as
, &argc
, error
);
2005 arg
= dm_shift_arg(as
);
2007 if (!strcasecmp(arg
, "writeback"))
2008 cf
->io_mode
= CM_IO_WRITEBACK
;
2010 else if (!strcasecmp(arg
, "writethrough"))
2011 cf
->io_mode
= CM_IO_WRITETHROUGH
;
2013 else if (!strcasecmp(arg
, "passthrough"))
2014 cf
->io_mode
= CM_IO_PASSTHROUGH
;
2017 *error
= "Unrecognised cache feature requested";
2025 static int parse_policy(struct cache_args
*ca
, struct dm_arg_set
*as
,
2028 static struct dm_arg _args
[] = {
2029 {0, 1024, "Invalid number of policy arguments"},
2034 if (!at_least_one_arg(as
, error
))
2037 ca
->policy_name
= dm_shift_arg(as
);
2039 r
= dm_read_arg_group(_args
, as
, &ca
->policy_argc
, error
);
2043 ca
->policy_argv
= (const char **)as
->argv
;
2044 dm_consume_args(as
, ca
->policy_argc
);
2049 static int parse_cache_args(struct cache_args
*ca
, int argc
, char **argv
,
2053 struct dm_arg_set as
;
2058 r
= parse_metadata_dev(ca
, &as
, error
);
2062 r
= parse_cache_dev(ca
, &as
, error
);
2066 r
= parse_origin_dev(ca
, &as
, error
);
2070 r
= parse_block_size(ca
, &as
, error
);
2074 r
= parse_features(ca
, &as
, error
);
2078 r
= parse_policy(ca
, &as
, error
);
2085 /*----------------------------------------------------------------*/
2087 static struct kmem_cache
*migration_cache
;
2089 #define NOT_CORE_OPTION 1
2091 static int process_config_option(struct cache
*cache
, const char *key
, const char *value
)
2095 if (!strcasecmp(key
, "migration_threshold")) {
2096 if (kstrtoul(value
, 10, &tmp
))
2099 cache
->migration_threshold
= tmp
;
2103 return NOT_CORE_OPTION
;
2106 static int set_config_value(struct cache
*cache
, const char *key
, const char *value
)
2108 int r
= process_config_option(cache
, key
, value
);
2110 if (r
== NOT_CORE_OPTION
)
2111 r
= policy_set_config_value(cache
->policy
, key
, value
);
2114 DMWARN("bad config value for %s: %s", key
, value
);
2119 static int set_config_values(struct cache
*cache
, int argc
, const char **argv
)
2124 DMWARN("Odd number of policy arguments given but they should be <key> <value> pairs.");
2129 r
= set_config_value(cache
, argv
[0], argv
[1]);
2140 static int create_cache_policy(struct cache
*cache
, struct cache_args
*ca
,
2143 struct dm_cache_policy
*p
= dm_cache_policy_create(ca
->policy_name
,
2145 cache
->origin_sectors
,
2146 cache
->sectors_per_block
);
2148 *error
= "Error creating cache's policy";
2156 #define DEFAULT_MIGRATION_THRESHOLD 2048
2158 static int cache_create(struct cache_args
*ca
, struct cache
**result
)
2161 char **error
= &ca
->ti
->error
;
2162 struct cache
*cache
;
2163 struct dm_target
*ti
= ca
->ti
;
2164 dm_block_t origin_blocks
;
2165 struct dm_cache_metadata
*cmd
;
2166 bool may_format
= ca
->features
.mode
== CM_WRITE
;
2168 cache
= kzalloc(sizeof(*cache
), GFP_KERNEL
);
2173 ti
->private = cache
;
2174 ti
->num_flush_bios
= 2;
2175 ti
->flush_supported
= true;
2177 ti
->num_discard_bios
= 1;
2178 ti
->discards_supported
= true;
2179 ti
->discard_zeroes_data_unsupported
= true;
2180 /* Discard bios must be split on a block boundary */
2181 ti
->split_discard_bios
= true;
2183 cache
->features
= ca
->features
;
2184 ti
->per_bio_data_size
= get_per_bio_data_size(cache
);
2186 cache
->callbacks
.congested_fn
= cache_is_congested
;
2187 dm_table_add_target_callbacks(ti
->table
, &cache
->callbacks
);
2189 cache
->metadata_dev
= ca
->metadata_dev
;
2190 cache
->origin_dev
= ca
->origin_dev
;
2191 cache
->cache_dev
= ca
->cache_dev
;
2193 ca
->metadata_dev
= ca
->origin_dev
= ca
->cache_dev
= NULL
;
2195 /* FIXME: factor out this whole section */
2196 origin_blocks
= cache
->origin_sectors
= ca
->origin_sectors
;
2197 origin_blocks
= block_div(origin_blocks
, ca
->block_size
);
2198 cache
->origin_blocks
= to_oblock(origin_blocks
);
2200 cache
->sectors_per_block
= ca
->block_size
;
2201 if (dm_set_target_max_io_len(ti
, cache
->sectors_per_block
)) {
2206 if (ca
->block_size
& (ca
->block_size
- 1)) {
2207 dm_block_t cache_size
= ca
->cache_sectors
;
2209 cache
->sectors_per_block_shift
= -1;
2210 cache_size
= block_div(cache_size
, ca
->block_size
);
2211 cache
->cache_size
= to_cblock(cache_size
);
2213 cache
->sectors_per_block_shift
= __ffs(ca
->block_size
);
2214 cache
->cache_size
= to_cblock(ca
->cache_sectors
>> cache
->sectors_per_block_shift
);
2217 r
= create_cache_policy(cache
, ca
, error
);
2221 cache
->policy_nr_args
= ca
->policy_argc
;
2222 cache
->migration_threshold
= DEFAULT_MIGRATION_THRESHOLD
;
2224 r
= set_config_values(cache
, ca
->policy_argc
, ca
->policy_argv
);
2226 *error
= "Error setting cache policy's config values";
2230 cmd
= dm_cache_metadata_open(cache
->metadata_dev
->bdev
,
2231 ca
->block_size
, may_format
,
2232 dm_cache_policy_get_hint_size(cache
->policy
));
2234 *error
= "Error creating metadata object";
2240 if (passthrough_mode(&cache
->features
)) {
2243 r
= dm_cache_metadata_all_clean(cache
->cmd
, &all_clean
);
2245 *error
= "dm_cache_metadata_all_clean() failed";
2250 *error
= "Cannot enter passthrough mode unless all blocks are clean";
2256 spin_lock_init(&cache
->lock
);
2257 bio_list_init(&cache
->deferred_bios
);
2258 bio_list_init(&cache
->deferred_flush_bios
);
2259 bio_list_init(&cache
->deferred_writethrough_bios
);
2260 INIT_LIST_HEAD(&cache
->quiesced_migrations
);
2261 INIT_LIST_HEAD(&cache
->completed_migrations
);
2262 INIT_LIST_HEAD(&cache
->need_commit_migrations
);
2263 atomic_set(&cache
->nr_migrations
, 0);
2264 init_waitqueue_head(&cache
->migration_wait
);
2266 init_waitqueue_head(&cache
->quiescing_wait
);
2267 atomic_set(&cache
->quiescing
, 0);
2268 atomic_set(&cache
->quiescing_ack
, 0);
2271 atomic_set(&cache
->nr_dirty
, 0);
2272 cache
->dirty_bitset
= alloc_bitset(from_cblock(cache
->cache_size
));
2273 if (!cache
->dirty_bitset
) {
2274 *error
= "could not allocate dirty bitset";
2277 clear_bitset(cache
->dirty_bitset
, from_cblock(cache
->cache_size
));
2279 cache
->discard_nr_blocks
= cache
->origin_blocks
;
2280 cache
->discard_bitset
= alloc_bitset(from_oblock(cache
->discard_nr_blocks
));
2281 if (!cache
->discard_bitset
) {
2282 *error
= "could not allocate discard bitset";
2285 clear_bitset(cache
->discard_bitset
, from_oblock(cache
->discard_nr_blocks
));
2287 cache
->copier
= dm_kcopyd_client_create(&dm_kcopyd_throttle
);
2288 if (IS_ERR(cache
->copier
)) {
2289 *error
= "could not create kcopyd client";
2290 r
= PTR_ERR(cache
->copier
);
2294 cache
->wq
= alloc_ordered_workqueue("dm-" DM_MSG_PREFIX
, WQ_MEM_RECLAIM
);
2296 *error
= "could not create workqueue for metadata object";
2299 INIT_WORK(&cache
->worker
, do_worker
);
2300 INIT_DELAYED_WORK(&cache
->waker
, do_waker
);
2301 cache
->last_commit_jiffies
= jiffies
;
2303 cache
->prison
= dm_bio_prison_create(PRISON_CELLS
);
2304 if (!cache
->prison
) {
2305 *error
= "could not create bio prison";
2309 cache
->all_io_ds
= dm_deferred_set_create();
2310 if (!cache
->all_io_ds
) {
2311 *error
= "could not create all_io deferred set";
2315 cache
->migration_pool
= mempool_create_slab_pool(MIGRATION_POOL_SIZE
,
2317 if (!cache
->migration_pool
) {
2318 *error
= "Error creating cache's migration mempool";
2322 cache
->next_migration
= NULL
;
2324 cache
->need_tick_bio
= true;
2325 cache
->sized
= false;
2326 cache
->invalidate
= false;
2327 cache
->commit_requested
= false;
2328 cache
->loaded_mappings
= false;
2329 cache
->loaded_discards
= false;
2333 atomic_set(&cache
->stats
.demotion
, 0);
2334 atomic_set(&cache
->stats
.promotion
, 0);
2335 atomic_set(&cache
->stats
.copies_avoided
, 0);
2336 atomic_set(&cache
->stats
.cache_cell_clash
, 0);
2337 atomic_set(&cache
->stats
.commit_count
, 0);
2338 atomic_set(&cache
->stats
.discard_count
, 0);
2340 spin_lock_init(&cache
->invalidation_lock
);
2341 INIT_LIST_HEAD(&cache
->invalidation_requests
);
2351 static int copy_ctr_args(struct cache
*cache
, int argc
, const char **argv
)
2356 copy
= kcalloc(argc
, sizeof(*copy
), GFP_KERNEL
);
2359 for (i
= 0; i
< argc
; i
++) {
2360 copy
[i
] = kstrdup(argv
[i
], GFP_KERNEL
);
2369 cache
->nr_ctr_args
= argc
;
2370 cache
->ctr_args
= copy
;
2375 static int cache_ctr(struct dm_target
*ti
, unsigned argc
, char **argv
)
2378 struct cache_args
*ca
;
2379 struct cache
*cache
= NULL
;
2381 ca
= kzalloc(sizeof(*ca
), GFP_KERNEL
);
2383 ti
->error
= "Error allocating memory for cache";
2388 r
= parse_cache_args(ca
, argc
, argv
, &ti
->error
);
2392 r
= cache_create(ca
, &cache
);
2396 r
= copy_ctr_args(cache
, argc
- 3, (const char **)argv
+ 3);
2402 ti
->private = cache
;
2405 destroy_cache_args(ca
);
2409 static int cache_map(struct dm_target
*ti
, struct bio
*bio
)
2411 struct cache
*cache
= ti
->private;
2414 dm_oblock_t block
= get_bio_block(cache
, bio
);
2415 size_t pb_data_size
= get_per_bio_data_size(cache
);
2416 bool can_migrate
= false;
2417 bool discarded_block
;
2418 struct dm_bio_prison_cell
*cell
;
2419 struct policy_result lookup_result
;
2420 struct per_bio_data
*pb
= init_per_bio_data(bio
, pb_data_size
);
2422 if (unlikely(from_oblock(block
) >= from_oblock(cache
->origin_blocks
))) {
2424 * This can only occur if the io goes to a partial block at
2425 * the end of the origin device. We don't cache these.
2426 * Just remap to the origin and carry on.
2428 remap_to_origin(cache
, bio
);
2429 return DM_MAPIO_REMAPPED
;
2432 if (bio
->bi_rw
& (REQ_FLUSH
| REQ_FUA
| REQ_DISCARD
)) {
2433 defer_bio(cache
, bio
);
2434 return DM_MAPIO_SUBMITTED
;
2438 * Check to see if that block is currently migrating.
2440 cell
= alloc_prison_cell(cache
);
2442 defer_bio(cache
, bio
);
2443 return DM_MAPIO_SUBMITTED
;
2446 r
= bio_detain(cache
, block
, bio
, cell
,
2447 (cell_free_fn
) free_prison_cell
,
2451 defer_bio(cache
, bio
);
2453 return DM_MAPIO_SUBMITTED
;
2456 discarded_block
= is_discarded_oblock(cache
, block
);
2458 r
= policy_map(cache
->policy
, block
, false, can_migrate
, discarded_block
,
2459 bio
, &lookup_result
);
2460 if (r
== -EWOULDBLOCK
) {
2461 cell_defer(cache
, cell
, true);
2462 return DM_MAPIO_SUBMITTED
;
2465 DMERR_LIMIT("Unexpected return from cache replacement policy: %d", r
);
2467 return DM_MAPIO_SUBMITTED
;
2470 r
= DM_MAPIO_REMAPPED
;
2471 switch (lookup_result
.op
) {
2473 if (passthrough_mode(&cache
->features
)) {
2474 if (bio_data_dir(bio
) == WRITE
) {
2476 * We need to invalidate this block, so
2477 * defer for the worker thread.
2479 cell_defer(cache
, cell
, true);
2480 r
= DM_MAPIO_SUBMITTED
;
2483 pb
->all_io_entry
= dm_deferred_entry_inc(cache
->all_io_ds
);
2484 inc_miss_counter(cache
, bio
);
2485 remap_to_origin_clear_discard(cache
, bio
, block
);
2487 cell_defer(cache
, cell
, false);
2491 inc_hit_counter(cache
, bio
);
2492 pb
->all_io_entry
= dm_deferred_entry_inc(cache
->all_io_ds
);
2494 if (bio_data_dir(bio
) == WRITE
&& writethrough_mode(&cache
->features
) &&
2495 !is_dirty(cache
, lookup_result
.cblock
))
2496 remap_to_origin_then_cache(cache
, bio
, block
, lookup_result
.cblock
);
2498 remap_to_cache_dirty(cache
, bio
, block
, lookup_result
.cblock
);
2500 cell_defer(cache
, cell
, false);
2505 inc_miss_counter(cache
, bio
);
2506 pb
->all_io_entry
= dm_deferred_entry_inc(cache
->all_io_ds
);
2508 if (pb
->req_nr
!= 0) {
2510 * This is a duplicate writethrough io that is no
2511 * longer needed because the block has been demoted.
2514 cell_defer(cache
, cell
, false);
2515 return DM_MAPIO_SUBMITTED
;
2517 remap_to_origin_clear_discard(cache
, bio
, block
);
2518 cell_defer(cache
, cell
, false);
2523 DMERR_LIMIT("%s: erroring bio: unknown policy op: %u", __func__
,
2524 (unsigned) lookup_result
.op
);
2526 r
= DM_MAPIO_SUBMITTED
;
2532 static int cache_end_io(struct dm_target
*ti
, struct bio
*bio
, int error
)
2534 struct cache
*cache
= ti
->private;
2535 unsigned long flags
;
2536 size_t pb_data_size
= get_per_bio_data_size(cache
);
2537 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
2540 policy_tick(cache
->policy
);
2542 spin_lock_irqsave(&cache
->lock
, flags
);
2543 cache
->need_tick_bio
= true;
2544 spin_unlock_irqrestore(&cache
->lock
, flags
);
2547 check_for_quiesced_migrations(cache
, pb
);
2552 static int write_dirty_bitset(struct cache
*cache
)
2556 for (i
= 0; i
< from_cblock(cache
->cache_size
); i
++) {
2557 r
= dm_cache_set_dirty(cache
->cmd
, to_cblock(i
),
2558 is_dirty(cache
, to_cblock(i
)));
2566 static int write_discard_bitset(struct cache
*cache
)
2570 r
= dm_cache_discard_bitset_resize(cache
->cmd
, cache
->sectors_per_block
,
2571 cache
->origin_blocks
);
2573 DMERR("could not resize on-disk discard bitset");
2577 for (i
= 0; i
< from_oblock(cache
->discard_nr_blocks
); i
++) {
2578 r
= dm_cache_set_discard(cache
->cmd
, to_oblock(i
),
2579 is_discarded(cache
, to_oblock(i
)));
2588 * returns true on success
2590 static bool sync_metadata(struct cache
*cache
)
2594 r1
= write_dirty_bitset(cache
);
2596 DMERR("could not write dirty bitset");
2598 r2
= write_discard_bitset(cache
);
2600 DMERR("could not write discard bitset");
2604 r3
= dm_cache_write_hints(cache
->cmd
, cache
->policy
);
2606 DMERR("could not write hints");
2609 * If writing the above metadata failed, we still commit, but don't
2610 * set the clean shutdown flag. This will effectively force every
2611 * dirty bit to be set on reload.
2613 r4
= dm_cache_commit(cache
->cmd
, !r1
&& !r2
&& !r3
);
2615 DMERR("could not write cache metadata. Data loss may occur.");
2617 return !r1
&& !r2
&& !r3
&& !r4
;
2620 static void cache_postsuspend(struct dm_target
*ti
)
2622 struct cache
*cache
= ti
->private;
2624 start_quiescing(cache
);
2625 wait_for_migrations(cache
);
2627 requeue_deferred_io(cache
);
2628 stop_quiescing(cache
);
2630 (void) sync_metadata(cache
);
2633 static int load_mapping(void *context
, dm_oblock_t oblock
, dm_cblock_t cblock
,
2634 bool dirty
, uint32_t hint
, bool hint_valid
)
2637 struct cache
*cache
= context
;
2639 r
= policy_load_mapping(cache
->policy
, oblock
, cblock
, hint
, hint_valid
);
2644 set_dirty(cache
, oblock
, cblock
);
2646 clear_dirty(cache
, oblock
, cblock
);
2651 static int load_discard(void *context
, sector_t discard_block_size
,
2652 dm_oblock_t oblock
, bool discard
)
2654 struct cache
*cache
= context
;
2657 set_discard(cache
, oblock
);
2659 clear_discard(cache
, oblock
);
2664 static dm_cblock_t
get_cache_dev_size(struct cache
*cache
)
2666 sector_t size
= get_dev_size(cache
->cache_dev
);
2667 (void) sector_div(size
, cache
->sectors_per_block
);
2668 return to_cblock(size
);
2671 static bool can_resize(struct cache
*cache
, dm_cblock_t new_size
)
2673 if (from_cblock(new_size
) > from_cblock(cache
->cache_size
))
2677 * We can't drop a dirty block when shrinking the cache.
2679 while (from_cblock(new_size
) < from_cblock(cache
->cache_size
)) {
2680 new_size
= to_cblock(from_cblock(new_size
) + 1);
2681 if (is_dirty(cache
, new_size
)) {
2682 DMERR("unable to shrink cache; cache block %llu is dirty",
2683 (unsigned long long) from_cblock(new_size
));
2691 static int resize_cache_dev(struct cache
*cache
, dm_cblock_t new_size
)
2695 r
= dm_cache_resize(cache
->cmd
, new_size
);
2697 DMERR("could not resize cache metadata");
2701 cache
->cache_size
= new_size
;
2706 static int cache_preresume(struct dm_target
*ti
)
2709 struct cache
*cache
= ti
->private;
2710 dm_cblock_t csize
= get_cache_dev_size(cache
);
2713 * Check to see if the cache has resized.
2715 if (!cache
->sized
) {
2716 r
= resize_cache_dev(cache
, csize
);
2720 cache
->sized
= true;
2722 } else if (csize
!= cache
->cache_size
) {
2723 if (!can_resize(cache
, csize
))
2726 r
= resize_cache_dev(cache
, csize
);
2731 if (!cache
->loaded_mappings
) {
2732 r
= dm_cache_load_mappings(cache
->cmd
, cache
->policy
,
2733 load_mapping
, cache
);
2735 DMERR("could not load cache mappings");
2739 cache
->loaded_mappings
= true;
2742 if (!cache
->loaded_discards
) {
2743 r
= dm_cache_load_discards(cache
->cmd
, load_discard
, cache
);
2745 DMERR("could not load origin discards");
2749 cache
->loaded_discards
= true;
2755 static void cache_resume(struct dm_target
*ti
)
2757 struct cache
*cache
= ti
->private;
2759 cache
->need_tick_bio
= true;
2760 do_waker(&cache
->waker
.work
);
2766 * <metadata block size> <#used metadata blocks>/<#total metadata blocks>
2767 * <cache block size> <#used cache blocks>/<#total cache blocks>
2768 * <#read hits> <#read misses> <#write hits> <#write misses>
2769 * <#demotions> <#promotions> <#dirty>
2770 * <#features> <features>*
2771 * <#core args> <core args>
2772 * <policy name> <#policy args> <policy args>*
2774 static void cache_status(struct dm_target
*ti
, status_type_t type
,
2775 unsigned status_flags
, char *result
, unsigned maxlen
)
2780 dm_block_t nr_free_blocks_metadata
= 0;
2781 dm_block_t nr_blocks_metadata
= 0;
2782 char buf
[BDEVNAME_SIZE
];
2783 struct cache
*cache
= ti
->private;
2784 dm_cblock_t residency
;
2787 case STATUSTYPE_INFO
:
2788 /* Commit to ensure statistics aren't out-of-date */
2789 if (!(status_flags
& DM_STATUS_NOFLUSH_FLAG
) && !dm_suspended(ti
)) {
2790 r
= dm_cache_commit(cache
->cmd
, false);
2792 DMERR("could not commit metadata for accurate status");
2795 r
= dm_cache_get_free_metadata_block_count(cache
->cmd
,
2796 &nr_free_blocks_metadata
);
2798 DMERR("could not get metadata free block count");
2802 r
= dm_cache_get_metadata_dev_size(cache
->cmd
, &nr_blocks_metadata
);
2804 DMERR("could not get metadata device size");
2808 residency
= policy_residency(cache
->policy
);
2810 DMEMIT("%u %llu/%llu %u %llu/%llu %u %u %u %u %u %u %lu ",
2811 (unsigned)(DM_CACHE_METADATA_BLOCK_SIZE
>> SECTOR_SHIFT
),
2812 (unsigned long long)(nr_blocks_metadata
- nr_free_blocks_metadata
),
2813 (unsigned long long)nr_blocks_metadata
,
2814 cache
->sectors_per_block
,
2815 (unsigned long long) from_cblock(residency
),
2816 (unsigned long long) from_cblock(cache
->cache_size
),
2817 (unsigned) atomic_read(&cache
->stats
.read_hit
),
2818 (unsigned) atomic_read(&cache
->stats
.read_miss
),
2819 (unsigned) atomic_read(&cache
->stats
.write_hit
),
2820 (unsigned) atomic_read(&cache
->stats
.write_miss
),
2821 (unsigned) atomic_read(&cache
->stats
.demotion
),
2822 (unsigned) atomic_read(&cache
->stats
.promotion
),
2823 (unsigned long) atomic_read(&cache
->nr_dirty
));
2825 if (writethrough_mode(&cache
->features
))
2826 DMEMIT("1 writethrough ");
2828 else if (passthrough_mode(&cache
->features
))
2829 DMEMIT("1 passthrough ");
2831 else if (writeback_mode(&cache
->features
))
2832 DMEMIT("1 writeback ");
2835 DMERR("internal error: unknown io mode: %d", (int) cache
->features
.io_mode
);
2839 DMEMIT("2 migration_threshold %llu ", (unsigned long long) cache
->migration_threshold
);
2841 DMEMIT("%s ", dm_cache_policy_get_name(cache
->policy
));
2843 r
= policy_emit_config_values(cache
->policy
, result
+ sz
, maxlen
- sz
);
2845 DMERR("policy_emit_config_values returned %d", r
);
2850 case STATUSTYPE_TABLE
:
2851 format_dev_t(buf
, cache
->metadata_dev
->bdev
->bd_dev
);
2853 format_dev_t(buf
, cache
->cache_dev
->bdev
->bd_dev
);
2855 format_dev_t(buf
, cache
->origin_dev
->bdev
->bd_dev
);
2858 for (i
= 0; i
< cache
->nr_ctr_args
- 1; i
++)
2859 DMEMIT(" %s", cache
->ctr_args
[i
]);
2860 if (cache
->nr_ctr_args
)
2861 DMEMIT(" %s", cache
->ctr_args
[cache
->nr_ctr_args
- 1]);
2871 * A cache block range can take two forms:
2873 * i) A single cblock, eg. '3456'
2874 * ii) A begin and end cblock with dots between, eg. 123-234
2876 static int parse_cblock_range(struct cache
*cache
, const char *str
,
2877 struct cblock_range
*result
)
2884 * Try and parse form (ii) first.
2886 r
= sscanf(str
, "%llu-%llu%c", &b
, &e
, &dummy
);
2891 result
->begin
= to_cblock(b
);
2892 result
->end
= to_cblock(e
);
2897 * That didn't work, try form (i).
2899 r
= sscanf(str
, "%llu%c", &b
, &dummy
);
2904 result
->begin
= to_cblock(b
);
2905 result
->end
= to_cblock(from_cblock(result
->begin
) + 1u);
2909 DMERR("invalid cblock range '%s'", str
);
2913 static int validate_cblock_range(struct cache
*cache
, struct cblock_range
*range
)
2915 uint64_t b
= from_cblock(range
->begin
);
2916 uint64_t e
= from_cblock(range
->end
);
2917 uint64_t n
= from_cblock(cache
->cache_size
);
2920 DMERR("begin cblock out of range: %llu >= %llu", b
, n
);
2925 DMERR("end cblock out of range: %llu > %llu", e
, n
);
2930 DMERR("invalid cblock range: %llu >= %llu", b
, e
);
2937 static int request_invalidation(struct cache
*cache
, struct cblock_range
*range
)
2939 struct invalidation_request req
;
2941 INIT_LIST_HEAD(&req
.list
);
2942 req
.cblocks
= range
;
2943 atomic_set(&req
.complete
, 0);
2945 init_waitqueue_head(&req
.result_wait
);
2947 spin_lock(&cache
->invalidation_lock
);
2948 list_add(&req
.list
, &cache
->invalidation_requests
);
2949 spin_unlock(&cache
->invalidation_lock
);
2952 wait_event(req
.result_wait
, atomic_read(&req
.complete
));
2956 static int process_invalidate_cblocks_message(struct cache
*cache
, unsigned count
,
2957 const char **cblock_ranges
)
2961 struct cblock_range range
;
2963 if (!passthrough_mode(&cache
->features
)) {
2964 DMERR("cache has to be in passthrough mode for invalidation");
2968 for (i
= 0; i
< count
; i
++) {
2969 r
= parse_cblock_range(cache
, cblock_ranges
[i
], &range
);
2973 r
= validate_cblock_range(cache
, &range
);
2978 * Pass begin and end origin blocks to the worker and wake it.
2980 r
= request_invalidation(cache
, &range
);
2992 * "invalidate_cblocks [(<begin>)|(<begin>-<end>)]*
2994 * The key migration_threshold is supported by the cache target core.
2996 static int cache_message(struct dm_target
*ti
, unsigned argc
, char **argv
)
2998 struct cache
*cache
= ti
->private;
3003 if (!strcasecmp(argv
[0], "invalidate_cblocks"))
3004 return process_invalidate_cblocks_message(cache
, argc
- 1, (const char **) argv
+ 1);
3009 return set_config_value(cache
, argv
[0], argv
[1]);
3012 static int cache_iterate_devices(struct dm_target
*ti
,
3013 iterate_devices_callout_fn fn
, void *data
)
3016 struct cache
*cache
= ti
->private;
3018 r
= fn(ti
, cache
->cache_dev
, 0, get_dev_size(cache
->cache_dev
), data
);
3020 r
= fn(ti
, cache
->origin_dev
, 0, ti
->len
, data
);
3026 * We assume I/O is going to the origin (which is the volume
3027 * more likely to have restrictions e.g. by being striped).
3028 * (Looking up the exact location of the data would be expensive
3029 * and could always be out of date by the time the bio is submitted.)
3031 static int cache_bvec_merge(struct dm_target
*ti
,
3032 struct bvec_merge_data
*bvm
,
3033 struct bio_vec
*biovec
, int max_size
)
3035 struct cache
*cache
= ti
->private;
3036 struct request_queue
*q
= bdev_get_queue(cache
->origin_dev
->bdev
);
3038 if (!q
->merge_bvec_fn
)
3041 bvm
->bi_bdev
= cache
->origin_dev
->bdev
;
3042 return min(max_size
, q
->merge_bvec_fn(q
, bvm
, biovec
));
3045 static void set_discard_limits(struct cache
*cache
, struct queue_limits
*limits
)
3048 * FIXME: these limits may be incompatible with the cache device
3050 limits
->max_discard_sectors
= cache
->sectors_per_block
;
3051 limits
->discard_granularity
= cache
->sectors_per_block
<< SECTOR_SHIFT
;
3054 static void cache_io_hints(struct dm_target
*ti
, struct queue_limits
*limits
)
3056 struct cache
*cache
= ti
->private;
3057 uint64_t io_opt_sectors
= limits
->io_opt
>> SECTOR_SHIFT
;
3060 * If the system-determined stacked limits are compatible with the
3061 * cache's blocksize (io_opt is a factor) do not override them.
3063 if (io_opt_sectors
< cache
->sectors_per_block
||
3064 do_div(io_opt_sectors
, cache
->sectors_per_block
)) {
3065 blk_limits_io_min(limits
, 0);
3066 blk_limits_io_opt(limits
, cache
->sectors_per_block
<< SECTOR_SHIFT
);
3068 set_discard_limits(cache
, limits
);
3071 /*----------------------------------------------------------------*/
3073 static struct target_type cache_target
= {
3075 .version
= {1, 4, 0},
3076 .module
= THIS_MODULE
,
3080 .end_io
= cache_end_io
,
3081 .postsuspend
= cache_postsuspend
,
3082 .preresume
= cache_preresume
,
3083 .resume
= cache_resume
,
3084 .status
= cache_status
,
3085 .message
= cache_message
,
3086 .iterate_devices
= cache_iterate_devices
,
3087 .merge
= cache_bvec_merge
,
3088 .io_hints
= cache_io_hints
,
3091 static int __init
dm_cache_init(void)
3095 r
= dm_register_target(&cache_target
);
3097 DMERR("cache target registration failed: %d", r
);
3101 migration_cache
= KMEM_CACHE(dm_cache_migration
, 0);
3102 if (!migration_cache
) {
3103 dm_unregister_target(&cache_target
);
3110 static void __exit
dm_cache_exit(void)
3112 dm_unregister_target(&cache_target
);
3113 kmem_cache_destroy(migration_cache
);
3116 module_init(dm_cache_init
);
3117 module_exit(dm_cache_exit
);
3119 MODULE_DESCRIPTION(DM_NAME
" cache target");
3120 MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
3121 MODULE_LICENSE("GPL");