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
);
722 * You must increment the deferred set whilst the prison cell is held. To
723 * encourage this, we ask for 'cell' to be passed in.
725 static void inc_ds(struct cache
*cache
, struct bio
*bio
,
726 struct dm_bio_prison_cell
*cell
)
728 size_t pb_data_size
= get_per_bio_data_size(cache
);
729 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
732 BUG_ON(pb
->all_io_entry
);
734 pb
->all_io_entry
= dm_deferred_entry_inc(cache
->all_io_ds
);
737 static void issue(struct cache
*cache
, struct bio
*bio
)
741 if (!bio_triggers_commit(cache
, bio
)) {
742 generic_make_request(bio
);
747 * Batch together any bios that trigger commits and then issue a
748 * single commit for them in do_worker().
750 spin_lock_irqsave(&cache
->lock
, flags
);
751 cache
->commit_requested
= true;
752 bio_list_add(&cache
->deferred_flush_bios
, bio
);
753 spin_unlock_irqrestore(&cache
->lock
, flags
);
756 static void inc_and_issue(struct cache
*cache
, struct bio
*bio
, struct dm_bio_prison_cell
*cell
)
758 inc_ds(cache
, bio
, cell
);
762 static void defer_writethrough_bio(struct cache
*cache
, struct bio
*bio
)
766 spin_lock_irqsave(&cache
->lock
, flags
);
767 bio_list_add(&cache
->deferred_writethrough_bios
, bio
);
768 spin_unlock_irqrestore(&cache
->lock
, flags
);
773 static void writethrough_endio(struct bio
*bio
, int err
)
775 struct per_bio_data
*pb
= get_per_bio_data(bio
, PB_DATA_SIZE_WT
);
777 dm_unhook_bio(&pb
->hook_info
, bio
);
784 dm_bio_restore(&pb
->bio_details
, bio
);
785 remap_to_cache(pb
->cache
, bio
, pb
->cblock
);
788 * We can't issue this bio directly, since we're in interrupt
789 * context. So it gets put on a bio list for processing by the
792 defer_writethrough_bio(pb
->cache
, bio
);
796 * When running in writethrough mode we need to send writes to clean blocks
797 * to both the cache and origin devices. In future we'd like to clone the
798 * bio and send them in parallel, but for now we're doing them in
799 * series as this is easier.
801 static void remap_to_origin_then_cache(struct cache
*cache
, struct bio
*bio
,
802 dm_oblock_t oblock
, dm_cblock_t cblock
)
804 struct per_bio_data
*pb
= get_per_bio_data(bio
, PB_DATA_SIZE_WT
);
808 dm_hook_bio(&pb
->hook_info
, bio
, writethrough_endio
, NULL
);
809 dm_bio_record(&pb
->bio_details
, bio
);
811 remap_to_origin_clear_discard(pb
->cache
, bio
, oblock
);
814 /*----------------------------------------------------------------
815 * Migration processing
817 * Migration covers moving data from the origin device to the cache, or
819 *--------------------------------------------------------------*/
820 static void free_migration(struct dm_cache_migration
*mg
)
822 mempool_free(mg
, mg
->cache
->migration_pool
);
825 static void inc_nr_migrations(struct cache
*cache
)
827 atomic_inc(&cache
->nr_migrations
);
830 static void dec_nr_migrations(struct cache
*cache
)
832 atomic_dec(&cache
->nr_migrations
);
835 * Wake the worker in case we're suspending the target.
837 wake_up(&cache
->migration_wait
);
840 static void __cell_defer(struct cache
*cache
, struct dm_bio_prison_cell
*cell
,
843 (holder
? dm_cell_release
: dm_cell_release_no_holder
)
844 (cache
->prison
, cell
, &cache
->deferred_bios
);
845 free_prison_cell(cache
, cell
);
848 static void cell_defer(struct cache
*cache
, struct dm_bio_prison_cell
*cell
,
853 spin_lock_irqsave(&cache
->lock
, flags
);
854 __cell_defer(cache
, cell
, holder
);
855 spin_unlock_irqrestore(&cache
->lock
, flags
);
860 static void cleanup_migration(struct dm_cache_migration
*mg
)
862 struct cache
*cache
= mg
->cache
;
864 dec_nr_migrations(cache
);
867 static void migration_failure(struct dm_cache_migration
*mg
)
869 struct cache
*cache
= mg
->cache
;
872 DMWARN_LIMIT("writeback failed; couldn't copy block");
873 set_dirty(cache
, mg
->old_oblock
, mg
->cblock
);
874 cell_defer(cache
, mg
->old_ocell
, false);
876 } else if (mg
->demote
) {
877 DMWARN_LIMIT("demotion failed; couldn't copy block");
878 policy_force_mapping(cache
->policy
, mg
->new_oblock
, mg
->old_oblock
);
880 cell_defer(cache
, mg
->old_ocell
, mg
->promote
? false : true);
882 cell_defer(cache
, mg
->new_ocell
, true);
884 DMWARN_LIMIT("promotion failed; couldn't copy block");
885 policy_remove_mapping(cache
->policy
, mg
->new_oblock
);
886 cell_defer(cache
, mg
->new_ocell
, true);
889 cleanup_migration(mg
);
892 static void migration_success_pre_commit(struct dm_cache_migration
*mg
)
895 struct cache
*cache
= mg
->cache
;
898 cell_defer(cache
, mg
->old_ocell
, false);
899 clear_dirty(cache
, mg
->old_oblock
, mg
->cblock
);
900 cleanup_migration(mg
);
903 } else if (mg
->demote
) {
904 if (dm_cache_remove_mapping(cache
->cmd
, mg
->cblock
)) {
905 DMWARN_LIMIT("demotion failed; couldn't update on disk metadata");
906 policy_force_mapping(cache
->policy
, mg
->new_oblock
,
909 cell_defer(cache
, mg
->new_ocell
, true);
910 cleanup_migration(mg
);
914 if (dm_cache_insert_mapping(cache
->cmd
, mg
->cblock
, mg
->new_oblock
)) {
915 DMWARN_LIMIT("promotion failed; couldn't update on disk metadata");
916 policy_remove_mapping(cache
->policy
, mg
->new_oblock
);
917 cleanup_migration(mg
);
922 spin_lock_irqsave(&cache
->lock
, flags
);
923 list_add_tail(&mg
->list
, &cache
->need_commit_migrations
);
924 cache
->commit_requested
= true;
925 spin_unlock_irqrestore(&cache
->lock
, flags
);
928 static void migration_success_post_commit(struct dm_cache_migration
*mg
)
931 struct cache
*cache
= mg
->cache
;
934 DMWARN("writeback unexpectedly triggered commit");
937 } else if (mg
->demote
) {
938 cell_defer(cache
, mg
->old_ocell
, mg
->promote
? false : true);
943 spin_lock_irqsave(&cache
->lock
, flags
);
944 list_add_tail(&mg
->list
, &cache
->quiesced_migrations
);
945 spin_unlock_irqrestore(&cache
->lock
, flags
);
949 policy_remove_mapping(cache
->policy
, mg
->old_oblock
);
950 cleanup_migration(mg
);
954 if (mg
->requeue_holder
)
955 cell_defer(cache
, mg
->new_ocell
, true);
957 bio_endio(mg
->new_ocell
->holder
, 0);
958 cell_defer(cache
, mg
->new_ocell
, false);
960 clear_dirty(cache
, mg
->new_oblock
, mg
->cblock
);
961 cleanup_migration(mg
);
965 static void copy_complete(int read_err
, unsigned long write_err
, void *context
)
968 struct dm_cache_migration
*mg
= (struct dm_cache_migration
*) context
;
969 struct cache
*cache
= mg
->cache
;
971 if (read_err
|| write_err
)
974 spin_lock_irqsave(&cache
->lock
, flags
);
975 list_add_tail(&mg
->list
, &cache
->completed_migrations
);
976 spin_unlock_irqrestore(&cache
->lock
, flags
);
981 static void issue_copy_real(struct dm_cache_migration
*mg
)
984 struct dm_io_region o_region
, c_region
;
985 struct cache
*cache
= mg
->cache
;
986 sector_t cblock
= from_cblock(mg
->cblock
);
988 o_region
.bdev
= cache
->origin_dev
->bdev
;
989 o_region
.count
= cache
->sectors_per_block
;
991 c_region
.bdev
= cache
->cache_dev
->bdev
;
992 c_region
.sector
= cblock
* cache
->sectors_per_block
;
993 c_region
.count
= cache
->sectors_per_block
;
995 if (mg
->writeback
|| mg
->demote
) {
997 o_region
.sector
= from_oblock(mg
->old_oblock
) * cache
->sectors_per_block
;
998 r
= dm_kcopyd_copy(cache
->copier
, &c_region
, 1, &o_region
, 0, copy_complete
, mg
);
1001 o_region
.sector
= from_oblock(mg
->new_oblock
) * cache
->sectors_per_block
;
1002 r
= dm_kcopyd_copy(cache
->copier
, &o_region
, 1, &c_region
, 0, copy_complete
, mg
);
1006 DMERR_LIMIT("issuing migration failed");
1007 migration_failure(mg
);
1011 static void overwrite_endio(struct bio
*bio
, int err
)
1013 struct dm_cache_migration
*mg
= bio
->bi_private
;
1014 struct cache
*cache
= mg
->cache
;
1015 size_t pb_data_size
= get_per_bio_data_size(cache
);
1016 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
1017 unsigned long flags
;
1019 dm_unhook_bio(&pb
->hook_info
, bio
);
1024 mg
->requeue_holder
= false;
1026 spin_lock_irqsave(&cache
->lock
, flags
);
1027 list_add_tail(&mg
->list
, &cache
->completed_migrations
);
1028 spin_unlock_irqrestore(&cache
->lock
, flags
);
1033 static void issue_overwrite(struct dm_cache_migration
*mg
, struct bio
*bio
)
1035 size_t pb_data_size
= get_per_bio_data_size(mg
->cache
);
1036 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
1038 dm_hook_bio(&pb
->hook_info
, bio
, overwrite_endio
, mg
);
1039 remap_to_cache_dirty(mg
->cache
, bio
, mg
->new_oblock
, mg
->cblock
);
1042 * No need to inc_ds() here, since the cell will be held for the
1043 * duration of the io.
1045 generic_make_request(bio
);
1048 static bool bio_writes_complete_block(struct cache
*cache
, struct bio
*bio
)
1050 return (bio_data_dir(bio
) == WRITE
) &&
1051 (bio
->bi_iter
.bi_size
== (cache
->sectors_per_block
<< SECTOR_SHIFT
));
1054 static void avoid_copy(struct dm_cache_migration
*mg
)
1056 atomic_inc(&mg
->cache
->stats
.copies_avoided
);
1057 migration_success_pre_commit(mg
);
1060 static void issue_copy(struct dm_cache_migration
*mg
)
1063 struct cache
*cache
= mg
->cache
;
1065 if (mg
->writeback
|| mg
->demote
)
1066 avoid
= !is_dirty(cache
, mg
->cblock
) ||
1067 is_discarded_oblock(cache
, mg
->old_oblock
);
1069 struct bio
*bio
= mg
->new_ocell
->holder
;
1071 avoid
= is_discarded_oblock(cache
, mg
->new_oblock
);
1073 if (!avoid
&& bio_writes_complete_block(cache
, bio
)) {
1074 issue_overwrite(mg
, bio
);
1079 avoid
? avoid_copy(mg
) : issue_copy_real(mg
);
1082 static void complete_migration(struct dm_cache_migration
*mg
)
1085 migration_failure(mg
);
1087 migration_success_pre_commit(mg
);
1090 static void process_migrations(struct cache
*cache
, struct list_head
*head
,
1091 void (*fn
)(struct dm_cache_migration
*))
1093 unsigned long flags
;
1094 struct list_head list
;
1095 struct dm_cache_migration
*mg
, *tmp
;
1097 INIT_LIST_HEAD(&list
);
1098 spin_lock_irqsave(&cache
->lock
, flags
);
1099 list_splice_init(head
, &list
);
1100 spin_unlock_irqrestore(&cache
->lock
, flags
);
1102 list_for_each_entry_safe(mg
, tmp
, &list
, list
)
1106 static void __queue_quiesced_migration(struct dm_cache_migration
*mg
)
1108 list_add_tail(&mg
->list
, &mg
->cache
->quiesced_migrations
);
1111 static void queue_quiesced_migration(struct dm_cache_migration
*mg
)
1113 unsigned long flags
;
1114 struct cache
*cache
= mg
->cache
;
1116 spin_lock_irqsave(&cache
->lock
, flags
);
1117 __queue_quiesced_migration(mg
);
1118 spin_unlock_irqrestore(&cache
->lock
, flags
);
1123 static void queue_quiesced_migrations(struct cache
*cache
, struct list_head
*work
)
1125 unsigned long flags
;
1126 struct dm_cache_migration
*mg
, *tmp
;
1128 spin_lock_irqsave(&cache
->lock
, flags
);
1129 list_for_each_entry_safe(mg
, tmp
, work
, list
)
1130 __queue_quiesced_migration(mg
);
1131 spin_unlock_irqrestore(&cache
->lock
, flags
);
1136 static void check_for_quiesced_migrations(struct cache
*cache
,
1137 struct per_bio_data
*pb
)
1139 struct list_head work
;
1141 if (!pb
->all_io_entry
)
1144 INIT_LIST_HEAD(&work
);
1145 dm_deferred_entry_dec(pb
->all_io_entry
, &work
);
1147 if (!list_empty(&work
))
1148 queue_quiesced_migrations(cache
, &work
);
1151 static void quiesce_migration(struct dm_cache_migration
*mg
)
1153 if (!dm_deferred_set_add_work(mg
->cache
->all_io_ds
, &mg
->list
))
1154 queue_quiesced_migration(mg
);
1157 static void promote(struct cache
*cache
, struct prealloc
*structs
,
1158 dm_oblock_t oblock
, dm_cblock_t cblock
,
1159 struct dm_bio_prison_cell
*cell
)
1161 struct dm_cache_migration
*mg
= prealloc_get_migration(structs
);
1164 mg
->writeback
= false;
1167 mg
->requeue_holder
= true;
1168 mg
->invalidate
= false;
1170 mg
->new_oblock
= oblock
;
1171 mg
->cblock
= cblock
;
1172 mg
->old_ocell
= NULL
;
1173 mg
->new_ocell
= cell
;
1174 mg
->start_jiffies
= jiffies
;
1176 inc_nr_migrations(cache
);
1177 quiesce_migration(mg
);
1180 static void writeback(struct cache
*cache
, struct prealloc
*structs
,
1181 dm_oblock_t oblock
, dm_cblock_t cblock
,
1182 struct dm_bio_prison_cell
*cell
)
1184 struct dm_cache_migration
*mg
= prealloc_get_migration(structs
);
1187 mg
->writeback
= true;
1189 mg
->promote
= false;
1190 mg
->requeue_holder
= true;
1191 mg
->invalidate
= false;
1193 mg
->old_oblock
= oblock
;
1194 mg
->cblock
= cblock
;
1195 mg
->old_ocell
= cell
;
1196 mg
->new_ocell
= NULL
;
1197 mg
->start_jiffies
= jiffies
;
1199 inc_nr_migrations(cache
);
1200 quiesce_migration(mg
);
1203 static void demote_then_promote(struct cache
*cache
, struct prealloc
*structs
,
1204 dm_oblock_t old_oblock
, dm_oblock_t new_oblock
,
1206 struct dm_bio_prison_cell
*old_ocell
,
1207 struct dm_bio_prison_cell
*new_ocell
)
1209 struct dm_cache_migration
*mg
= prealloc_get_migration(structs
);
1212 mg
->writeback
= false;
1215 mg
->requeue_holder
= true;
1216 mg
->invalidate
= false;
1218 mg
->old_oblock
= old_oblock
;
1219 mg
->new_oblock
= new_oblock
;
1220 mg
->cblock
= cblock
;
1221 mg
->old_ocell
= old_ocell
;
1222 mg
->new_ocell
= new_ocell
;
1223 mg
->start_jiffies
= jiffies
;
1225 inc_nr_migrations(cache
);
1226 quiesce_migration(mg
);
1230 * Invalidate a cache entry. No writeback occurs; any changes in the cache
1231 * block are thrown away.
1233 static void invalidate(struct cache
*cache
, struct prealloc
*structs
,
1234 dm_oblock_t oblock
, dm_cblock_t cblock
,
1235 struct dm_bio_prison_cell
*cell
)
1237 struct dm_cache_migration
*mg
= prealloc_get_migration(structs
);
1240 mg
->writeback
= false;
1242 mg
->promote
= false;
1243 mg
->requeue_holder
= true;
1244 mg
->invalidate
= true;
1246 mg
->old_oblock
= oblock
;
1247 mg
->cblock
= cblock
;
1248 mg
->old_ocell
= cell
;
1249 mg
->new_ocell
= NULL
;
1250 mg
->start_jiffies
= jiffies
;
1252 inc_nr_migrations(cache
);
1253 quiesce_migration(mg
);
1256 /*----------------------------------------------------------------
1258 *--------------------------------------------------------------*/
1259 static void defer_bio(struct cache
*cache
, struct bio
*bio
)
1261 unsigned long flags
;
1263 spin_lock_irqsave(&cache
->lock
, flags
);
1264 bio_list_add(&cache
->deferred_bios
, bio
);
1265 spin_unlock_irqrestore(&cache
->lock
, flags
);
1270 static void process_flush_bio(struct cache
*cache
, struct bio
*bio
)
1272 size_t pb_data_size
= get_per_bio_data_size(cache
);
1273 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
1275 BUG_ON(bio
->bi_iter
.bi_size
);
1277 remap_to_origin(cache
, bio
);
1279 remap_to_cache(cache
, bio
, 0);
1282 * REQ_FLUSH is not directed at any particular block so we don't
1283 * need to inc_ds(). REQ_FUA's are split into a write + REQ_FLUSH
1290 * People generally discard large parts of a device, eg, the whole device
1291 * when formatting. Splitting these large discards up into cache block
1292 * sized ios and then quiescing (always neccessary for discard) takes too
1295 * We keep it simple, and allow any size of discard to come in, and just
1296 * mark off blocks on the discard bitset. No passdown occurs!
1298 * To implement passdown we need to change the bio_prison such that a cell
1299 * can have a key that spans many blocks.
1301 static void process_discard_bio(struct cache
*cache
, struct bio
*bio
)
1303 dm_block_t start_block
= dm_sector_div_up(bio
->bi_iter
.bi_sector
,
1304 cache
->sectors_per_block
);
1305 dm_block_t end_block
= bio_end_sector(bio
);
1308 end_block
= block_div(end_block
, cache
->sectors_per_block
);
1310 for (b
= start_block
; b
< end_block
; b
++)
1311 set_discard(cache
, to_oblock(b
));
1316 static bool spare_migration_bandwidth(struct cache
*cache
)
1318 sector_t current_volume
= (atomic_read(&cache
->nr_migrations
) + 1) *
1319 cache
->sectors_per_block
;
1320 return current_volume
< cache
->migration_threshold
;
1323 static void inc_hit_counter(struct cache
*cache
, struct bio
*bio
)
1325 atomic_inc(bio_data_dir(bio
) == READ
?
1326 &cache
->stats
.read_hit
: &cache
->stats
.write_hit
);
1329 static void inc_miss_counter(struct cache
*cache
, struct bio
*bio
)
1331 atomic_inc(bio_data_dir(bio
) == READ
?
1332 &cache
->stats
.read_miss
: &cache
->stats
.write_miss
);
1335 static void process_bio(struct cache
*cache
, struct prealloc
*structs
,
1339 bool release_cell
= true;
1340 dm_oblock_t block
= get_bio_block(cache
, bio
);
1341 struct dm_bio_prison_cell
*cell_prealloc
, *old_ocell
, *new_ocell
;
1342 struct policy_result lookup_result
;
1343 bool discarded_block
= is_discarded_oblock(cache
, block
);
1344 bool passthrough
= passthrough_mode(&cache
->features
);
1345 bool can_migrate
= !passthrough
&& (discarded_block
|| spare_migration_bandwidth(cache
));
1348 * Check to see if that block is currently migrating.
1350 cell_prealloc
= prealloc_get_cell(structs
);
1351 r
= bio_detain(cache
, block
, bio
, cell_prealloc
,
1352 (cell_free_fn
) prealloc_put_cell
,
1353 structs
, &new_ocell
);
1357 r
= policy_map(cache
->policy
, block
, true, can_migrate
, discarded_block
,
1358 bio
, &lookup_result
);
1360 if (r
== -EWOULDBLOCK
)
1361 /* migration has been denied */
1362 lookup_result
.op
= POLICY_MISS
;
1364 switch (lookup_result
.op
) {
1367 inc_miss_counter(cache
, bio
);
1370 * Passthrough always maps to the origin,
1371 * invalidating any cache blocks that are written
1375 if (bio_data_dir(bio
) == WRITE
) {
1376 atomic_inc(&cache
->stats
.demotion
);
1377 invalidate(cache
, structs
, block
, lookup_result
.cblock
, new_ocell
);
1378 release_cell
= false;
1381 /* FIXME: factor out issue_origin() */
1382 remap_to_origin_clear_discard(cache
, bio
, block
);
1383 inc_and_issue(cache
, bio
, new_ocell
);
1386 inc_hit_counter(cache
, bio
);
1388 if (bio_data_dir(bio
) == WRITE
&&
1389 writethrough_mode(&cache
->features
) &&
1390 !is_dirty(cache
, lookup_result
.cblock
)) {
1391 remap_to_origin_then_cache(cache
, bio
, block
, lookup_result
.cblock
);
1392 inc_and_issue(cache
, bio
, new_ocell
);
1395 remap_to_cache_dirty(cache
, bio
, block
, lookup_result
.cblock
);
1396 inc_and_issue(cache
, bio
, new_ocell
);
1403 inc_miss_counter(cache
, bio
);
1404 remap_to_origin_clear_discard(cache
, bio
, block
);
1405 inc_and_issue(cache
, bio
, new_ocell
);
1409 atomic_inc(&cache
->stats
.promotion
);
1410 promote(cache
, structs
, block
, lookup_result
.cblock
, new_ocell
);
1411 release_cell
= false;
1414 case POLICY_REPLACE
:
1415 cell_prealloc
= prealloc_get_cell(structs
);
1416 r
= bio_detain(cache
, lookup_result
.old_oblock
, bio
, cell_prealloc
,
1417 (cell_free_fn
) prealloc_put_cell
,
1418 structs
, &old_ocell
);
1421 * We have to be careful to avoid lock inversion of
1422 * the cells. So we back off, and wait for the
1423 * old_ocell to become free.
1425 policy_force_mapping(cache
->policy
, block
,
1426 lookup_result
.old_oblock
);
1427 atomic_inc(&cache
->stats
.cache_cell_clash
);
1430 atomic_inc(&cache
->stats
.demotion
);
1431 atomic_inc(&cache
->stats
.promotion
);
1433 demote_then_promote(cache
, structs
, lookup_result
.old_oblock
,
1434 block
, lookup_result
.cblock
,
1435 old_ocell
, new_ocell
);
1436 release_cell
= false;
1440 DMERR_LIMIT("%s: erroring bio, unknown policy op: %u", __func__
,
1441 (unsigned) lookup_result
.op
);
1446 cell_defer(cache
, new_ocell
, false);
1449 static int need_commit_due_to_time(struct cache
*cache
)
1451 return jiffies
< cache
->last_commit_jiffies
||
1452 jiffies
> cache
->last_commit_jiffies
+ COMMIT_PERIOD
;
1455 static int commit_if_needed(struct cache
*cache
)
1459 if ((cache
->commit_requested
|| need_commit_due_to_time(cache
)) &&
1460 dm_cache_changed_this_transaction(cache
->cmd
)) {
1461 atomic_inc(&cache
->stats
.commit_count
);
1462 cache
->commit_requested
= false;
1463 r
= dm_cache_commit(cache
->cmd
, false);
1464 cache
->last_commit_jiffies
= jiffies
;
1470 static void process_deferred_bios(struct cache
*cache
)
1472 unsigned long flags
;
1473 struct bio_list bios
;
1475 struct prealloc structs
;
1477 memset(&structs
, 0, sizeof(structs
));
1478 bio_list_init(&bios
);
1480 spin_lock_irqsave(&cache
->lock
, flags
);
1481 bio_list_merge(&bios
, &cache
->deferred_bios
);
1482 bio_list_init(&cache
->deferred_bios
);
1483 spin_unlock_irqrestore(&cache
->lock
, flags
);
1485 while (!bio_list_empty(&bios
)) {
1487 * If we've got no free migration structs, and processing
1488 * this bio might require one, we pause until there are some
1489 * prepared mappings to process.
1491 if (prealloc_data_structs(cache
, &structs
)) {
1492 spin_lock_irqsave(&cache
->lock
, flags
);
1493 bio_list_merge(&cache
->deferred_bios
, &bios
);
1494 spin_unlock_irqrestore(&cache
->lock
, flags
);
1498 bio
= bio_list_pop(&bios
);
1500 if (bio
->bi_rw
& REQ_FLUSH
)
1501 process_flush_bio(cache
, bio
);
1502 else if (bio
->bi_rw
& REQ_DISCARD
)
1503 process_discard_bio(cache
, bio
);
1505 process_bio(cache
, &structs
, bio
);
1508 prealloc_free_structs(cache
, &structs
);
1511 static void process_deferred_flush_bios(struct cache
*cache
, bool submit_bios
)
1513 unsigned long flags
;
1514 struct bio_list bios
;
1517 bio_list_init(&bios
);
1519 spin_lock_irqsave(&cache
->lock
, flags
);
1520 bio_list_merge(&bios
, &cache
->deferred_flush_bios
);
1521 bio_list_init(&cache
->deferred_flush_bios
);
1522 spin_unlock_irqrestore(&cache
->lock
, flags
);
1525 * These bios have already been through inc_ds()
1527 while ((bio
= bio_list_pop(&bios
)))
1528 submit_bios
? generic_make_request(bio
) : bio_io_error(bio
);
1531 static void process_deferred_writethrough_bios(struct cache
*cache
)
1533 unsigned long flags
;
1534 struct bio_list bios
;
1537 bio_list_init(&bios
);
1539 spin_lock_irqsave(&cache
->lock
, flags
);
1540 bio_list_merge(&bios
, &cache
->deferred_writethrough_bios
);
1541 bio_list_init(&cache
->deferred_writethrough_bios
);
1542 spin_unlock_irqrestore(&cache
->lock
, flags
);
1545 * These bios have already been through inc_ds()
1547 while ((bio
= bio_list_pop(&bios
)))
1548 generic_make_request(bio
);
1551 static void writeback_some_dirty_blocks(struct cache
*cache
)
1556 struct prealloc structs
;
1557 struct dm_bio_prison_cell
*old_ocell
;
1559 memset(&structs
, 0, sizeof(structs
));
1561 while (spare_migration_bandwidth(cache
)) {
1562 if (prealloc_data_structs(cache
, &structs
))
1565 r
= policy_writeback_work(cache
->policy
, &oblock
, &cblock
);
1569 r
= get_cell(cache
, oblock
, &structs
, &old_ocell
);
1571 policy_set_dirty(cache
->policy
, oblock
);
1575 writeback(cache
, &structs
, oblock
, cblock
, old_ocell
);
1578 prealloc_free_structs(cache
, &structs
);
1581 /*----------------------------------------------------------------
1583 * Dropping something from the cache *without* writing back.
1584 *--------------------------------------------------------------*/
1586 static void process_invalidation_request(struct cache
*cache
, struct invalidation_request
*req
)
1589 uint64_t begin
= from_cblock(req
->cblocks
->begin
);
1590 uint64_t end
= from_cblock(req
->cblocks
->end
);
1592 while (begin
!= end
) {
1593 r
= policy_remove_cblock(cache
->policy
, to_cblock(begin
));
1595 r
= dm_cache_remove_mapping(cache
->cmd
, to_cblock(begin
));
1599 } else if (r
== -ENODATA
) {
1600 /* harmless, already unmapped */
1604 DMERR("policy_remove_cblock failed");
1611 cache
->commit_requested
= true;
1614 atomic_set(&req
->complete
, 1);
1616 wake_up(&req
->result_wait
);
1619 static void process_invalidation_requests(struct cache
*cache
)
1621 struct list_head list
;
1622 struct invalidation_request
*req
, *tmp
;
1624 INIT_LIST_HEAD(&list
);
1625 spin_lock(&cache
->invalidation_lock
);
1626 list_splice_init(&cache
->invalidation_requests
, &list
);
1627 spin_unlock(&cache
->invalidation_lock
);
1629 list_for_each_entry_safe (req
, tmp
, &list
, list
)
1630 process_invalidation_request(cache
, req
);
1633 /*----------------------------------------------------------------
1635 *--------------------------------------------------------------*/
1636 static bool is_quiescing(struct cache
*cache
)
1638 return atomic_read(&cache
->quiescing
);
1641 static void ack_quiescing(struct cache
*cache
)
1643 if (is_quiescing(cache
)) {
1644 atomic_inc(&cache
->quiescing_ack
);
1645 wake_up(&cache
->quiescing_wait
);
1649 static void wait_for_quiescing_ack(struct cache
*cache
)
1651 wait_event(cache
->quiescing_wait
, atomic_read(&cache
->quiescing_ack
));
1654 static void start_quiescing(struct cache
*cache
)
1656 atomic_inc(&cache
->quiescing
);
1657 wait_for_quiescing_ack(cache
);
1660 static void stop_quiescing(struct cache
*cache
)
1662 atomic_set(&cache
->quiescing
, 0);
1663 atomic_set(&cache
->quiescing_ack
, 0);
1666 static void wait_for_migrations(struct cache
*cache
)
1668 wait_event(cache
->migration_wait
, !atomic_read(&cache
->nr_migrations
));
1671 static void stop_worker(struct cache
*cache
)
1673 cancel_delayed_work(&cache
->waker
);
1674 flush_workqueue(cache
->wq
);
1677 static void requeue_deferred_io(struct cache
*cache
)
1680 struct bio_list bios
;
1682 bio_list_init(&bios
);
1683 bio_list_merge(&bios
, &cache
->deferred_bios
);
1684 bio_list_init(&cache
->deferred_bios
);
1686 while ((bio
= bio_list_pop(&bios
)))
1687 bio_endio(bio
, DM_ENDIO_REQUEUE
);
1690 static int more_work(struct cache
*cache
)
1692 if (is_quiescing(cache
))
1693 return !list_empty(&cache
->quiesced_migrations
) ||
1694 !list_empty(&cache
->completed_migrations
) ||
1695 !list_empty(&cache
->need_commit_migrations
);
1697 return !bio_list_empty(&cache
->deferred_bios
) ||
1698 !bio_list_empty(&cache
->deferred_flush_bios
) ||
1699 !bio_list_empty(&cache
->deferred_writethrough_bios
) ||
1700 !list_empty(&cache
->quiesced_migrations
) ||
1701 !list_empty(&cache
->completed_migrations
) ||
1702 !list_empty(&cache
->need_commit_migrations
) ||
1706 static void do_worker(struct work_struct
*ws
)
1708 struct cache
*cache
= container_of(ws
, struct cache
, worker
);
1711 if (!is_quiescing(cache
)) {
1712 writeback_some_dirty_blocks(cache
);
1713 process_deferred_writethrough_bios(cache
);
1714 process_deferred_bios(cache
);
1715 process_invalidation_requests(cache
);
1718 process_migrations(cache
, &cache
->quiesced_migrations
, issue_copy
);
1719 process_migrations(cache
, &cache
->completed_migrations
, complete_migration
);
1721 if (commit_if_needed(cache
)) {
1722 process_deferred_flush_bios(cache
, false);
1723 process_migrations(cache
, &cache
->need_commit_migrations
, migration_failure
);
1726 * FIXME: rollback metadata or just go into a
1727 * failure mode and error everything
1730 process_deferred_flush_bios(cache
, true);
1731 process_migrations(cache
, &cache
->need_commit_migrations
,
1732 migration_success_post_commit
);
1735 ack_quiescing(cache
);
1737 } while (more_work(cache
));
1741 * We want to commit periodically so that not too much
1742 * unwritten metadata builds up.
1744 static void do_waker(struct work_struct
*ws
)
1746 struct cache
*cache
= container_of(to_delayed_work(ws
), struct cache
, waker
);
1747 policy_tick(cache
->policy
);
1749 queue_delayed_work(cache
->wq
, &cache
->waker
, COMMIT_PERIOD
);
1752 /*----------------------------------------------------------------*/
1754 static int is_congested(struct dm_dev
*dev
, int bdi_bits
)
1756 struct request_queue
*q
= bdev_get_queue(dev
->bdev
);
1757 return bdi_congested(&q
->backing_dev_info
, bdi_bits
);
1760 static int cache_is_congested(struct dm_target_callbacks
*cb
, int bdi_bits
)
1762 struct cache
*cache
= container_of(cb
, struct cache
, callbacks
);
1764 return is_congested(cache
->origin_dev
, bdi_bits
) ||
1765 is_congested(cache
->cache_dev
, bdi_bits
);
1768 /*----------------------------------------------------------------
1770 *--------------------------------------------------------------*/
1773 * This function gets called on the error paths of the constructor, so we
1774 * have to cope with a partially initialised struct.
1776 static void destroy(struct cache
*cache
)
1780 if (cache
->next_migration
)
1781 mempool_free(cache
->next_migration
, cache
->migration_pool
);
1783 if (cache
->migration_pool
)
1784 mempool_destroy(cache
->migration_pool
);
1786 if (cache
->all_io_ds
)
1787 dm_deferred_set_destroy(cache
->all_io_ds
);
1790 dm_bio_prison_destroy(cache
->prison
);
1793 destroy_workqueue(cache
->wq
);
1795 if (cache
->dirty_bitset
)
1796 free_bitset(cache
->dirty_bitset
);
1798 if (cache
->discard_bitset
)
1799 free_bitset(cache
->discard_bitset
);
1802 dm_kcopyd_client_destroy(cache
->copier
);
1805 dm_cache_metadata_close(cache
->cmd
);
1807 if (cache
->metadata_dev
)
1808 dm_put_device(cache
->ti
, cache
->metadata_dev
);
1810 if (cache
->origin_dev
)
1811 dm_put_device(cache
->ti
, cache
->origin_dev
);
1813 if (cache
->cache_dev
)
1814 dm_put_device(cache
->ti
, cache
->cache_dev
);
1817 dm_cache_policy_destroy(cache
->policy
);
1819 for (i
= 0; i
< cache
->nr_ctr_args
; i
++)
1820 kfree(cache
->ctr_args
[i
]);
1821 kfree(cache
->ctr_args
);
1826 static void cache_dtr(struct dm_target
*ti
)
1828 struct cache
*cache
= ti
->private;
1833 static sector_t
get_dev_size(struct dm_dev
*dev
)
1835 return i_size_read(dev
->bdev
->bd_inode
) >> SECTOR_SHIFT
;
1838 /*----------------------------------------------------------------*/
1841 * Construct a cache device mapping.
1843 * cache <metadata dev> <cache dev> <origin dev> <block size>
1844 * <#feature args> [<feature arg>]*
1845 * <policy> <#policy args> [<policy arg>]*
1847 * metadata dev : fast device holding the persistent metadata
1848 * cache dev : fast device holding cached data blocks
1849 * origin dev : slow device holding original data blocks
1850 * block size : cache unit size in sectors
1852 * #feature args : number of feature arguments passed
1853 * feature args : writethrough. (The default is writeback.)
1855 * policy : the replacement policy to use
1856 * #policy args : an even number of policy arguments corresponding
1857 * to key/value pairs passed to the policy
1858 * policy args : key/value pairs passed to the policy
1859 * E.g. 'sequential_threshold 1024'
1860 * See cache-policies.txt for details.
1862 * Optional feature arguments are:
1863 * writethrough : write through caching that prohibits cache block
1864 * content from being different from origin block content.
1865 * Without this argument, the default behaviour is to write
1866 * back cache block contents later for performance reasons,
1867 * so they may differ from the corresponding origin blocks.
1870 struct dm_target
*ti
;
1872 struct dm_dev
*metadata_dev
;
1874 struct dm_dev
*cache_dev
;
1875 sector_t cache_sectors
;
1877 struct dm_dev
*origin_dev
;
1878 sector_t origin_sectors
;
1880 uint32_t block_size
;
1882 const char *policy_name
;
1884 const char **policy_argv
;
1886 struct cache_features features
;
1889 static void destroy_cache_args(struct cache_args
*ca
)
1891 if (ca
->metadata_dev
)
1892 dm_put_device(ca
->ti
, ca
->metadata_dev
);
1895 dm_put_device(ca
->ti
, ca
->cache_dev
);
1898 dm_put_device(ca
->ti
, ca
->origin_dev
);
1903 static bool at_least_one_arg(struct dm_arg_set
*as
, char **error
)
1906 *error
= "Insufficient args";
1913 static int parse_metadata_dev(struct cache_args
*ca
, struct dm_arg_set
*as
,
1917 sector_t metadata_dev_size
;
1918 char b
[BDEVNAME_SIZE
];
1920 if (!at_least_one_arg(as
, error
))
1923 r
= dm_get_device(ca
->ti
, dm_shift_arg(as
), FMODE_READ
| FMODE_WRITE
,
1926 *error
= "Error opening metadata device";
1930 metadata_dev_size
= get_dev_size(ca
->metadata_dev
);
1931 if (metadata_dev_size
> DM_CACHE_METADATA_MAX_SECTORS_WARNING
)
1932 DMWARN("Metadata device %s is larger than %u sectors: excess space will not be used.",
1933 bdevname(ca
->metadata_dev
->bdev
, b
), THIN_METADATA_MAX_SECTORS
);
1938 static int parse_cache_dev(struct cache_args
*ca
, struct dm_arg_set
*as
,
1943 if (!at_least_one_arg(as
, error
))
1946 r
= dm_get_device(ca
->ti
, dm_shift_arg(as
), FMODE_READ
| FMODE_WRITE
,
1949 *error
= "Error opening cache device";
1952 ca
->cache_sectors
= get_dev_size(ca
->cache_dev
);
1957 static int parse_origin_dev(struct cache_args
*ca
, struct dm_arg_set
*as
,
1962 if (!at_least_one_arg(as
, error
))
1965 r
= dm_get_device(ca
->ti
, dm_shift_arg(as
), FMODE_READ
| FMODE_WRITE
,
1968 *error
= "Error opening origin device";
1972 ca
->origin_sectors
= get_dev_size(ca
->origin_dev
);
1973 if (ca
->ti
->len
> ca
->origin_sectors
) {
1974 *error
= "Device size larger than cached device";
1981 static int parse_block_size(struct cache_args
*ca
, struct dm_arg_set
*as
,
1984 unsigned long block_size
;
1986 if (!at_least_one_arg(as
, error
))
1989 if (kstrtoul(dm_shift_arg(as
), 10, &block_size
) || !block_size
||
1990 block_size
< DATA_DEV_BLOCK_SIZE_MIN_SECTORS
||
1991 block_size
> DATA_DEV_BLOCK_SIZE_MAX_SECTORS
||
1992 block_size
& (DATA_DEV_BLOCK_SIZE_MIN_SECTORS
- 1)) {
1993 *error
= "Invalid data block size";
1997 if (block_size
> ca
->cache_sectors
) {
1998 *error
= "Data block size is larger than the cache device";
2002 ca
->block_size
= block_size
;
2007 static void init_features(struct cache_features
*cf
)
2009 cf
->mode
= CM_WRITE
;
2010 cf
->io_mode
= CM_IO_WRITEBACK
;
2013 static int parse_features(struct cache_args
*ca
, struct dm_arg_set
*as
,
2016 static struct dm_arg _args
[] = {
2017 {0, 1, "Invalid number of cache feature arguments"},
2023 struct cache_features
*cf
= &ca
->features
;
2027 r
= dm_read_arg_group(_args
, as
, &argc
, error
);
2032 arg
= dm_shift_arg(as
);
2034 if (!strcasecmp(arg
, "writeback"))
2035 cf
->io_mode
= CM_IO_WRITEBACK
;
2037 else if (!strcasecmp(arg
, "writethrough"))
2038 cf
->io_mode
= CM_IO_WRITETHROUGH
;
2040 else if (!strcasecmp(arg
, "passthrough"))
2041 cf
->io_mode
= CM_IO_PASSTHROUGH
;
2044 *error
= "Unrecognised cache feature requested";
2052 static int parse_policy(struct cache_args
*ca
, struct dm_arg_set
*as
,
2055 static struct dm_arg _args
[] = {
2056 {0, 1024, "Invalid number of policy arguments"},
2061 if (!at_least_one_arg(as
, error
))
2064 ca
->policy_name
= dm_shift_arg(as
);
2066 r
= dm_read_arg_group(_args
, as
, &ca
->policy_argc
, error
);
2070 ca
->policy_argv
= (const char **)as
->argv
;
2071 dm_consume_args(as
, ca
->policy_argc
);
2076 static int parse_cache_args(struct cache_args
*ca
, int argc
, char **argv
,
2080 struct dm_arg_set as
;
2085 r
= parse_metadata_dev(ca
, &as
, error
);
2089 r
= parse_cache_dev(ca
, &as
, error
);
2093 r
= parse_origin_dev(ca
, &as
, error
);
2097 r
= parse_block_size(ca
, &as
, error
);
2101 r
= parse_features(ca
, &as
, error
);
2105 r
= parse_policy(ca
, &as
, error
);
2112 /*----------------------------------------------------------------*/
2114 static struct kmem_cache
*migration_cache
;
2116 #define NOT_CORE_OPTION 1
2118 static int process_config_option(struct cache
*cache
, const char *key
, const char *value
)
2122 if (!strcasecmp(key
, "migration_threshold")) {
2123 if (kstrtoul(value
, 10, &tmp
))
2126 cache
->migration_threshold
= tmp
;
2130 return NOT_CORE_OPTION
;
2133 static int set_config_value(struct cache
*cache
, const char *key
, const char *value
)
2135 int r
= process_config_option(cache
, key
, value
);
2137 if (r
== NOT_CORE_OPTION
)
2138 r
= policy_set_config_value(cache
->policy
, key
, value
);
2141 DMWARN("bad config value for %s: %s", key
, value
);
2146 static int set_config_values(struct cache
*cache
, int argc
, const char **argv
)
2151 DMWARN("Odd number of policy arguments given but they should be <key> <value> pairs.");
2156 r
= set_config_value(cache
, argv
[0], argv
[1]);
2167 static int create_cache_policy(struct cache
*cache
, struct cache_args
*ca
,
2170 struct dm_cache_policy
*p
= dm_cache_policy_create(ca
->policy_name
,
2172 cache
->origin_sectors
,
2173 cache
->sectors_per_block
);
2175 *error
= "Error creating cache's policy";
2183 #define DEFAULT_MIGRATION_THRESHOLD 2048
2185 static int cache_create(struct cache_args
*ca
, struct cache
**result
)
2188 char **error
= &ca
->ti
->error
;
2189 struct cache
*cache
;
2190 struct dm_target
*ti
= ca
->ti
;
2191 dm_block_t origin_blocks
;
2192 struct dm_cache_metadata
*cmd
;
2193 bool may_format
= ca
->features
.mode
== CM_WRITE
;
2195 cache
= kzalloc(sizeof(*cache
), GFP_KERNEL
);
2200 ti
->private = cache
;
2201 ti
->num_flush_bios
= 2;
2202 ti
->flush_supported
= true;
2204 ti
->num_discard_bios
= 1;
2205 ti
->discards_supported
= true;
2206 ti
->discard_zeroes_data_unsupported
= true;
2207 /* Discard bios must be split on a block boundary */
2208 ti
->split_discard_bios
= true;
2210 cache
->features
= ca
->features
;
2211 ti
->per_bio_data_size
= get_per_bio_data_size(cache
);
2213 cache
->callbacks
.congested_fn
= cache_is_congested
;
2214 dm_table_add_target_callbacks(ti
->table
, &cache
->callbacks
);
2216 cache
->metadata_dev
= ca
->metadata_dev
;
2217 cache
->origin_dev
= ca
->origin_dev
;
2218 cache
->cache_dev
= ca
->cache_dev
;
2220 ca
->metadata_dev
= ca
->origin_dev
= ca
->cache_dev
= NULL
;
2222 /* FIXME: factor out this whole section */
2223 origin_blocks
= cache
->origin_sectors
= ca
->origin_sectors
;
2224 origin_blocks
= block_div(origin_blocks
, ca
->block_size
);
2225 cache
->origin_blocks
= to_oblock(origin_blocks
);
2227 cache
->sectors_per_block
= ca
->block_size
;
2228 if (dm_set_target_max_io_len(ti
, cache
->sectors_per_block
)) {
2233 if (ca
->block_size
& (ca
->block_size
- 1)) {
2234 dm_block_t cache_size
= ca
->cache_sectors
;
2236 cache
->sectors_per_block_shift
= -1;
2237 cache_size
= block_div(cache_size
, ca
->block_size
);
2238 cache
->cache_size
= to_cblock(cache_size
);
2240 cache
->sectors_per_block_shift
= __ffs(ca
->block_size
);
2241 cache
->cache_size
= to_cblock(ca
->cache_sectors
>> cache
->sectors_per_block_shift
);
2244 r
= create_cache_policy(cache
, ca
, error
);
2248 cache
->policy_nr_args
= ca
->policy_argc
;
2249 cache
->migration_threshold
= DEFAULT_MIGRATION_THRESHOLD
;
2251 r
= set_config_values(cache
, ca
->policy_argc
, ca
->policy_argv
);
2253 *error
= "Error setting cache policy's config values";
2257 cmd
= dm_cache_metadata_open(cache
->metadata_dev
->bdev
,
2258 ca
->block_size
, may_format
,
2259 dm_cache_policy_get_hint_size(cache
->policy
));
2261 *error
= "Error creating metadata object";
2267 if (passthrough_mode(&cache
->features
)) {
2270 r
= dm_cache_metadata_all_clean(cache
->cmd
, &all_clean
);
2272 *error
= "dm_cache_metadata_all_clean() failed";
2277 *error
= "Cannot enter passthrough mode unless all blocks are clean";
2283 spin_lock_init(&cache
->lock
);
2284 bio_list_init(&cache
->deferred_bios
);
2285 bio_list_init(&cache
->deferred_flush_bios
);
2286 bio_list_init(&cache
->deferred_writethrough_bios
);
2287 INIT_LIST_HEAD(&cache
->quiesced_migrations
);
2288 INIT_LIST_HEAD(&cache
->completed_migrations
);
2289 INIT_LIST_HEAD(&cache
->need_commit_migrations
);
2290 atomic_set(&cache
->nr_migrations
, 0);
2291 init_waitqueue_head(&cache
->migration_wait
);
2293 init_waitqueue_head(&cache
->quiescing_wait
);
2294 atomic_set(&cache
->quiescing
, 0);
2295 atomic_set(&cache
->quiescing_ack
, 0);
2298 atomic_set(&cache
->nr_dirty
, 0);
2299 cache
->dirty_bitset
= alloc_bitset(from_cblock(cache
->cache_size
));
2300 if (!cache
->dirty_bitset
) {
2301 *error
= "could not allocate dirty bitset";
2304 clear_bitset(cache
->dirty_bitset
, from_cblock(cache
->cache_size
));
2306 cache
->discard_nr_blocks
= cache
->origin_blocks
;
2307 cache
->discard_bitset
= alloc_bitset(from_oblock(cache
->discard_nr_blocks
));
2308 if (!cache
->discard_bitset
) {
2309 *error
= "could not allocate discard bitset";
2312 clear_bitset(cache
->discard_bitset
, from_oblock(cache
->discard_nr_blocks
));
2314 cache
->copier
= dm_kcopyd_client_create(&dm_kcopyd_throttle
);
2315 if (IS_ERR(cache
->copier
)) {
2316 *error
= "could not create kcopyd client";
2317 r
= PTR_ERR(cache
->copier
);
2321 cache
->wq
= alloc_ordered_workqueue("dm-" DM_MSG_PREFIX
, WQ_MEM_RECLAIM
);
2323 *error
= "could not create workqueue for metadata object";
2326 INIT_WORK(&cache
->worker
, do_worker
);
2327 INIT_DELAYED_WORK(&cache
->waker
, do_waker
);
2328 cache
->last_commit_jiffies
= jiffies
;
2330 cache
->prison
= dm_bio_prison_create(PRISON_CELLS
);
2331 if (!cache
->prison
) {
2332 *error
= "could not create bio prison";
2336 cache
->all_io_ds
= dm_deferred_set_create();
2337 if (!cache
->all_io_ds
) {
2338 *error
= "could not create all_io deferred set";
2342 cache
->migration_pool
= mempool_create_slab_pool(MIGRATION_POOL_SIZE
,
2344 if (!cache
->migration_pool
) {
2345 *error
= "Error creating cache's migration mempool";
2349 cache
->next_migration
= NULL
;
2351 cache
->need_tick_bio
= true;
2352 cache
->sized
= false;
2353 cache
->invalidate
= false;
2354 cache
->commit_requested
= false;
2355 cache
->loaded_mappings
= false;
2356 cache
->loaded_discards
= false;
2360 atomic_set(&cache
->stats
.demotion
, 0);
2361 atomic_set(&cache
->stats
.promotion
, 0);
2362 atomic_set(&cache
->stats
.copies_avoided
, 0);
2363 atomic_set(&cache
->stats
.cache_cell_clash
, 0);
2364 atomic_set(&cache
->stats
.commit_count
, 0);
2365 atomic_set(&cache
->stats
.discard_count
, 0);
2367 spin_lock_init(&cache
->invalidation_lock
);
2368 INIT_LIST_HEAD(&cache
->invalidation_requests
);
2378 static int copy_ctr_args(struct cache
*cache
, int argc
, const char **argv
)
2383 copy
= kcalloc(argc
, sizeof(*copy
), GFP_KERNEL
);
2386 for (i
= 0; i
< argc
; i
++) {
2387 copy
[i
] = kstrdup(argv
[i
], GFP_KERNEL
);
2396 cache
->nr_ctr_args
= argc
;
2397 cache
->ctr_args
= copy
;
2402 static int cache_ctr(struct dm_target
*ti
, unsigned argc
, char **argv
)
2405 struct cache_args
*ca
;
2406 struct cache
*cache
= NULL
;
2408 ca
= kzalloc(sizeof(*ca
), GFP_KERNEL
);
2410 ti
->error
= "Error allocating memory for cache";
2415 r
= parse_cache_args(ca
, argc
, argv
, &ti
->error
);
2419 r
= cache_create(ca
, &cache
);
2423 r
= copy_ctr_args(cache
, argc
- 3, (const char **)argv
+ 3);
2429 ti
->private = cache
;
2432 destroy_cache_args(ca
);
2436 static int __cache_map(struct cache
*cache
, struct bio
*bio
, struct dm_bio_prison_cell
**cell
)
2439 dm_oblock_t block
= get_bio_block(cache
, bio
);
2440 size_t pb_data_size
= get_per_bio_data_size(cache
);
2441 bool can_migrate
= false;
2442 bool discarded_block
;
2443 struct policy_result lookup_result
;
2444 struct per_bio_data
*pb
= init_per_bio_data(bio
, pb_data_size
);
2446 if (unlikely(from_oblock(block
) >= from_oblock(cache
->origin_blocks
))) {
2448 * This can only occur if the io goes to a partial block at
2449 * the end of the origin device. We don't cache these.
2450 * Just remap to the origin and carry on.
2452 remap_to_origin(cache
, bio
);
2453 return DM_MAPIO_REMAPPED
;
2456 if (bio
->bi_rw
& (REQ_FLUSH
| REQ_FUA
| REQ_DISCARD
)) {
2457 defer_bio(cache
, bio
);
2458 return DM_MAPIO_SUBMITTED
;
2462 * Check to see if that block is currently migrating.
2464 *cell
= alloc_prison_cell(cache
);
2466 defer_bio(cache
, bio
);
2467 return DM_MAPIO_SUBMITTED
;
2470 r
= bio_detain(cache
, block
, bio
, *cell
,
2471 (cell_free_fn
) free_prison_cell
,
2475 defer_bio(cache
, bio
);
2477 return DM_MAPIO_SUBMITTED
;
2480 discarded_block
= is_discarded_oblock(cache
, block
);
2482 r
= policy_map(cache
->policy
, block
, false, can_migrate
, discarded_block
,
2483 bio
, &lookup_result
);
2484 if (r
== -EWOULDBLOCK
) {
2485 cell_defer(cache
, *cell
, true);
2486 return DM_MAPIO_SUBMITTED
;
2489 DMERR_LIMIT("Unexpected return from cache replacement policy: %d", r
);
2490 cell_defer(cache
, *cell
, false);
2492 return DM_MAPIO_SUBMITTED
;
2495 r
= DM_MAPIO_REMAPPED
;
2496 switch (lookup_result
.op
) {
2498 if (passthrough_mode(&cache
->features
)) {
2499 if (bio_data_dir(bio
) == WRITE
) {
2501 * We need to invalidate this block, so
2502 * defer for the worker thread.
2504 cell_defer(cache
, *cell
, true);
2505 r
= DM_MAPIO_SUBMITTED
;
2508 inc_miss_counter(cache
, bio
);
2509 remap_to_origin_clear_discard(cache
, bio
, block
);
2513 inc_hit_counter(cache
, bio
);
2514 if (bio_data_dir(bio
) == WRITE
&& writethrough_mode(&cache
->features
) &&
2515 !is_dirty(cache
, lookup_result
.cblock
))
2516 remap_to_origin_then_cache(cache
, bio
, block
, lookup_result
.cblock
);
2518 remap_to_cache_dirty(cache
, bio
, block
, lookup_result
.cblock
);
2523 inc_miss_counter(cache
, bio
);
2524 if (pb
->req_nr
!= 0) {
2526 * This is a duplicate writethrough io that is no
2527 * longer needed because the block has been demoted.
2530 cell_defer(cache
, *cell
, false);
2531 r
= DM_MAPIO_SUBMITTED
;
2534 remap_to_origin_clear_discard(cache
, bio
, block
);
2539 DMERR_LIMIT("%s: erroring bio: unknown policy op: %u", __func__
,
2540 (unsigned) lookup_result
.op
);
2541 cell_defer(cache
, *cell
, false);
2543 r
= DM_MAPIO_SUBMITTED
;
2549 static int cache_map(struct dm_target
*ti
, struct bio
*bio
)
2552 struct dm_bio_prison_cell
*cell
;
2553 struct cache
*cache
= ti
->private;
2555 r
= __cache_map(cache
, bio
, &cell
);
2556 if (r
== DM_MAPIO_REMAPPED
) {
2557 inc_ds(cache
, bio
, cell
);
2558 cell_defer(cache
, cell
, false);
2564 static int cache_end_io(struct dm_target
*ti
, struct bio
*bio
, int error
)
2566 struct cache
*cache
= ti
->private;
2567 unsigned long flags
;
2568 size_t pb_data_size
= get_per_bio_data_size(cache
);
2569 struct per_bio_data
*pb
= get_per_bio_data(bio
, pb_data_size
);
2572 policy_tick(cache
->policy
);
2574 spin_lock_irqsave(&cache
->lock
, flags
);
2575 cache
->need_tick_bio
= true;
2576 spin_unlock_irqrestore(&cache
->lock
, flags
);
2579 check_for_quiesced_migrations(cache
, pb
);
2584 static int write_dirty_bitset(struct cache
*cache
)
2588 for (i
= 0; i
< from_cblock(cache
->cache_size
); i
++) {
2589 r
= dm_cache_set_dirty(cache
->cmd
, to_cblock(i
),
2590 is_dirty(cache
, to_cblock(i
)));
2598 static int write_discard_bitset(struct cache
*cache
)
2602 r
= dm_cache_discard_bitset_resize(cache
->cmd
, cache
->sectors_per_block
,
2603 cache
->origin_blocks
);
2605 DMERR("could not resize on-disk discard bitset");
2609 for (i
= 0; i
< from_oblock(cache
->discard_nr_blocks
); i
++) {
2610 r
= dm_cache_set_discard(cache
->cmd
, to_oblock(i
),
2611 is_discarded(cache
, to_oblock(i
)));
2620 * returns true on success
2622 static bool sync_metadata(struct cache
*cache
)
2626 r1
= write_dirty_bitset(cache
);
2628 DMERR("could not write dirty bitset");
2630 r2
= write_discard_bitset(cache
);
2632 DMERR("could not write discard bitset");
2636 r3
= dm_cache_write_hints(cache
->cmd
, cache
->policy
);
2638 DMERR("could not write hints");
2641 * If writing the above metadata failed, we still commit, but don't
2642 * set the clean shutdown flag. This will effectively force every
2643 * dirty bit to be set on reload.
2645 r4
= dm_cache_commit(cache
->cmd
, !r1
&& !r2
&& !r3
);
2647 DMERR("could not write cache metadata. Data loss may occur.");
2649 return !r1
&& !r2
&& !r3
&& !r4
;
2652 static void cache_postsuspend(struct dm_target
*ti
)
2654 struct cache
*cache
= ti
->private;
2656 start_quiescing(cache
);
2657 wait_for_migrations(cache
);
2659 requeue_deferred_io(cache
);
2660 stop_quiescing(cache
);
2662 (void) sync_metadata(cache
);
2665 static int load_mapping(void *context
, dm_oblock_t oblock
, dm_cblock_t cblock
,
2666 bool dirty
, uint32_t hint
, bool hint_valid
)
2669 struct cache
*cache
= context
;
2671 r
= policy_load_mapping(cache
->policy
, oblock
, cblock
, hint
, hint_valid
);
2676 set_dirty(cache
, oblock
, cblock
);
2678 clear_dirty(cache
, oblock
, cblock
);
2683 static int load_discard(void *context
, sector_t discard_block_size
,
2684 dm_oblock_t oblock
, bool discard
)
2686 struct cache
*cache
= context
;
2689 set_discard(cache
, oblock
);
2691 clear_discard(cache
, oblock
);
2696 static dm_cblock_t
get_cache_dev_size(struct cache
*cache
)
2698 sector_t size
= get_dev_size(cache
->cache_dev
);
2699 (void) sector_div(size
, cache
->sectors_per_block
);
2700 return to_cblock(size
);
2703 static bool can_resize(struct cache
*cache
, dm_cblock_t new_size
)
2705 if (from_cblock(new_size
) > from_cblock(cache
->cache_size
))
2709 * We can't drop a dirty block when shrinking the cache.
2711 while (from_cblock(new_size
) < from_cblock(cache
->cache_size
)) {
2712 new_size
= to_cblock(from_cblock(new_size
) + 1);
2713 if (is_dirty(cache
, new_size
)) {
2714 DMERR("unable to shrink cache; cache block %llu is dirty",
2715 (unsigned long long) from_cblock(new_size
));
2723 static int resize_cache_dev(struct cache
*cache
, dm_cblock_t new_size
)
2727 r
= dm_cache_resize(cache
->cmd
, new_size
);
2729 DMERR("could not resize cache metadata");
2733 cache
->cache_size
= new_size
;
2738 static int cache_preresume(struct dm_target
*ti
)
2741 struct cache
*cache
= ti
->private;
2742 dm_cblock_t csize
= get_cache_dev_size(cache
);
2745 * Check to see if the cache has resized.
2747 if (!cache
->sized
) {
2748 r
= resize_cache_dev(cache
, csize
);
2752 cache
->sized
= true;
2754 } else if (csize
!= cache
->cache_size
) {
2755 if (!can_resize(cache
, csize
))
2758 r
= resize_cache_dev(cache
, csize
);
2763 if (!cache
->loaded_mappings
) {
2764 r
= dm_cache_load_mappings(cache
->cmd
, cache
->policy
,
2765 load_mapping
, cache
);
2767 DMERR("could not load cache mappings");
2771 cache
->loaded_mappings
= true;
2774 if (!cache
->loaded_discards
) {
2775 r
= dm_cache_load_discards(cache
->cmd
, load_discard
, cache
);
2777 DMERR("could not load origin discards");
2781 cache
->loaded_discards
= true;
2787 static void cache_resume(struct dm_target
*ti
)
2789 struct cache
*cache
= ti
->private;
2791 cache
->need_tick_bio
= true;
2792 do_waker(&cache
->waker
.work
);
2798 * <metadata block size> <#used metadata blocks>/<#total metadata blocks>
2799 * <cache block size> <#used cache blocks>/<#total cache blocks>
2800 * <#read hits> <#read misses> <#write hits> <#write misses>
2801 * <#demotions> <#promotions> <#dirty>
2802 * <#features> <features>*
2803 * <#core args> <core args>
2804 * <policy name> <#policy args> <policy args>*
2806 static void cache_status(struct dm_target
*ti
, status_type_t type
,
2807 unsigned status_flags
, char *result
, unsigned maxlen
)
2812 dm_block_t nr_free_blocks_metadata
= 0;
2813 dm_block_t nr_blocks_metadata
= 0;
2814 char buf
[BDEVNAME_SIZE
];
2815 struct cache
*cache
= ti
->private;
2816 dm_cblock_t residency
;
2819 case STATUSTYPE_INFO
:
2820 /* Commit to ensure statistics aren't out-of-date */
2821 if (!(status_flags
& DM_STATUS_NOFLUSH_FLAG
) && !dm_suspended(ti
)) {
2822 r
= dm_cache_commit(cache
->cmd
, false);
2824 DMERR("could not commit metadata for accurate status");
2827 r
= dm_cache_get_free_metadata_block_count(cache
->cmd
,
2828 &nr_free_blocks_metadata
);
2830 DMERR("could not get metadata free block count");
2834 r
= dm_cache_get_metadata_dev_size(cache
->cmd
, &nr_blocks_metadata
);
2836 DMERR("could not get metadata device size");
2840 residency
= policy_residency(cache
->policy
);
2842 DMEMIT("%u %llu/%llu %u %llu/%llu %u %u %u %u %u %u %lu ",
2843 (unsigned)DM_CACHE_METADATA_BLOCK_SIZE
,
2844 (unsigned long long)(nr_blocks_metadata
- nr_free_blocks_metadata
),
2845 (unsigned long long)nr_blocks_metadata
,
2846 cache
->sectors_per_block
,
2847 (unsigned long long) from_cblock(residency
),
2848 (unsigned long long) from_cblock(cache
->cache_size
),
2849 (unsigned) atomic_read(&cache
->stats
.read_hit
),
2850 (unsigned) atomic_read(&cache
->stats
.read_miss
),
2851 (unsigned) atomic_read(&cache
->stats
.write_hit
),
2852 (unsigned) atomic_read(&cache
->stats
.write_miss
),
2853 (unsigned) atomic_read(&cache
->stats
.demotion
),
2854 (unsigned) atomic_read(&cache
->stats
.promotion
),
2855 (unsigned long) atomic_read(&cache
->nr_dirty
));
2857 if (writethrough_mode(&cache
->features
))
2858 DMEMIT("1 writethrough ");
2860 else if (passthrough_mode(&cache
->features
))
2861 DMEMIT("1 passthrough ");
2863 else if (writeback_mode(&cache
->features
))
2864 DMEMIT("1 writeback ");
2867 DMERR("internal error: unknown io mode: %d", (int) cache
->features
.io_mode
);
2871 DMEMIT("2 migration_threshold %llu ", (unsigned long long) cache
->migration_threshold
);
2873 DMEMIT("%s ", dm_cache_policy_get_name(cache
->policy
));
2875 r
= policy_emit_config_values(cache
->policy
, result
+ sz
, maxlen
- sz
);
2877 DMERR("policy_emit_config_values returned %d", r
);
2882 case STATUSTYPE_TABLE
:
2883 format_dev_t(buf
, cache
->metadata_dev
->bdev
->bd_dev
);
2885 format_dev_t(buf
, cache
->cache_dev
->bdev
->bd_dev
);
2887 format_dev_t(buf
, cache
->origin_dev
->bdev
->bd_dev
);
2890 for (i
= 0; i
< cache
->nr_ctr_args
- 1; i
++)
2891 DMEMIT(" %s", cache
->ctr_args
[i
]);
2892 if (cache
->nr_ctr_args
)
2893 DMEMIT(" %s", cache
->ctr_args
[cache
->nr_ctr_args
- 1]);
2903 * A cache block range can take two forms:
2905 * i) A single cblock, eg. '3456'
2906 * ii) A begin and end cblock with dots between, eg. 123-234
2908 static int parse_cblock_range(struct cache
*cache
, const char *str
,
2909 struct cblock_range
*result
)
2916 * Try and parse form (ii) first.
2918 r
= sscanf(str
, "%llu-%llu%c", &b
, &e
, &dummy
);
2923 result
->begin
= to_cblock(b
);
2924 result
->end
= to_cblock(e
);
2929 * That didn't work, try form (i).
2931 r
= sscanf(str
, "%llu%c", &b
, &dummy
);
2936 result
->begin
= to_cblock(b
);
2937 result
->end
= to_cblock(from_cblock(result
->begin
) + 1u);
2941 DMERR("invalid cblock range '%s'", str
);
2945 static int validate_cblock_range(struct cache
*cache
, struct cblock_range
*range
)
2947 uint64_t b
= from_cblock(range
->begin
);
2948 uint64_t e
= from_cblock(range
->end
);
2949 uint64_t n
= from_cblock(cache
->cache_size
);
2952 DMERR("begin cblock out of range: %llu >= %llu", b
, n
);
2957 DMERR("end cblock out of range: %llu > %llu", e
, n
);
2962 DMERR("invalid cblock range: %llu >= %llu", b
, e
);
2969 static int request_invalidation(struct cache
*cache
, struct cblock_range
*range
)
2971 struct invalidation_request req
;
2973 INIT_LIST_HEAD(&req
.list
);
2974 req
.cblocks
= range
;
2975 atomic_set(&req
.complete
, 0);
2977 init_waitqueue_head(&req
.result_wait
);
2979 spin_lock(&cache
->invalidation_lock
);
2980 list_add(&req
.list
, &cache
->invalidation_requests
);
2981 spin_unlock(&cache
->invalidation_lock
);
2984 wait_event(req
.result_wait
, atomic_read(&req
.complete
));
2988 static int process_invalidate_cblocks_message(struct cache
*cache
, unsigned count
,
2989 const char **cblock_ranges
)
2993 struct cblock_range range
;
2995 if (!passthrough_mode(&cache
->features
)) {
2996 DMERR("cache has to be in passthrough mode for invalidation");
3000 for (i
= 0; i
< count
; i
++) {
3001 r
= parse_cblock_range(cache
, cblock_ranges
[i
], &range
);
3005 r
= validate_cblock_range(cache
, &range
);
3010 * Pass begin and end origin blocks to the worker and wake it.
3012 r
= request_invalidation(cache
, &range
);
3024 * "invalidate_cblocks [(<begin>)|(<begin>-<end>)]*
3026 * The key migration_threshold is supported by the cache target core.
3028 static int cache_message(struct dm_target
*ti
, unsigned argc
, char **argv
)
3030 struct cache
*cache
= ti
->private;
3035 if (!strcasecmp(argv
[0], "invalidate_cblocks"))
3036 return process_invalidate_cblocks_message(cache
, argc
- 1, (const char **) argv
+ 1);
3041 return set_config_value(cache
, argv
[0], argv
[1]);
3044 static int cache_iterate_devices(struct dm_target
*ti
,
3045 iterate_devices_callout_fn fn
, void *data
)
3048 struct cache
*cache
= ti
->private;
3050 r
= fn(ti
, cache
->cache_dev
, 0, get_dev_size(cache
->cache_dev
), data
);
3052 r
= fn(ti
, cache
->origin_dev
, 0, ti
->len
, data
);
3058 * We assume I/O is going to the origin (which is the volume
3059 * more likely to have restrictions e.g. by being striped).
3060 * (Looking up the exact location of the data would be expensive
3061 * and could always be out of date by the time the bio is submitted.)
3063 static int cache_bvec_merge(struct dm_target
*ti
,
3064 struct bvec_merge_data
*bvm
,
3065 struct bio_vec
*biovec
, int max_size
)
3067 struct cache
*cache
= ti
->private;
3068 struct request_queue
*q
= bdev_get_queue(cache
->origin_dev
->bdev
);
3070 if (!q
->merge_bvec_fn
)
3073 bvm
->bi_bdev
= cache
->origin_dev
->bdev
;
3074 return min(max_size
, q
->merge_bvec_fn(q
, bvm
, biovec
));
3077 static void set_discard_limits(struct cache
*cache
, struct queue_limits
*limits
)
3080 * FIXME: these limits may be incompatible with the cache device
3082 limits
->max_discard_sectors
= cache
->sectors_per_block
;
3083 limits
->discard_granularity
= cache
->sectors_per_block
<< SECTOR_SHIFT
;
3086 static void cache_io_hints(struct dm_target
*ti
, struct queue_limits
*limits
)
3088 struct cache
*cache
= ti
->private;
3089 uint64_t io_opt_sectors
= limits
->io_opt
>> SECTOR_SHIFT
;
3092 * If the system-determined stacked limits are compatible with the
3093 * cache's blocksize (io_opt is a factor) do not override them.
3095 if (io_opt_sectors
< cache
->sectors_per_block
||
3096 do_div(io_opt_sectors
, cache
->sectors_per_block
)) {
3097 blk_limits_io_min(limits
, cache
->sectors_per_block
<< SECTOR_SHIFT
);
3098 blk_limits_io_opt(limits
, cache
->sectors_per_block
<< SECTOR_SHIFT
);
3100 set_discard_limits(cache
, limits
);
3103 /*----------------------------------------------------------------*/
3105 static struct target_type cache_target
= {
3107 .version
= {1, 5, 0},
3108 .module
= THIS_MODULE
,
3112 .end_io
= cache_end_io
,
3113 .postsuspend
= cache_postsuspend
,
3114 .preresume
= cache_preresume
,
3115 .resume
= cache_resume
,
3116 .status
= cache_status
,
3117 .message
= cache_message
,
3118 .iterate_devices
= cache_iterate_devices
,
3119 .merge
= cache_bvec_merge
,
3120 .io_hints
= cache_io_hints
,
3123 static int __init
dm_cache_init(void)
3127 r
= dm_register_target(&cache_target
);
3129 DMERR("cache target registration failed: %d", r
);
3133 migration_cache
= KMEM_CACHE(dm_cache_migration
, 0);
3134 if (!migration_cache
) {
3135 dm_unregister_target(&cache_target
);
3142 static void __exit
dm_cache_exit(void)
3144 dm_unregister_target(&cache_target
);
3145 kmem_cache_destroy(migration_cache
);
3148 module_init(dm_cache_init
);
3149 module_exit(dm_cache_exit
);
3151 MODULE_DESCRIPTION(DM_NAME
" cache target");
3152 MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
3153 MODULE_LICENSE("GPL");