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1/*
2 * Copyright (C) 2012 Red Hat. All rights reserved.
3 *
4 * This file is released under the GPL.
5 */
6
7#include "dm.h"
8#include "dm-bio-prison-v2.h"
9#include "dm-bio-record.h"
10#include "dm-cache-metadata.h"
11#include "dm-io-tracker.h"
12
13#include <linux/dm-io.h>
14#include <linux/dm-kcopyd.h>
15#include <linux/jiffies.h>
16#include <linux/init.h>
17#include <linux/mempool.h>
18#include <linux/module.h>
19#include <linux/rwsem.h>
20#include <linux/slab.h>
21#include <linux/vmalloc.h>
22
23#define DM_MSG_PREFIX "cache"
24
25DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(cache_copy_throttle,
26 "A percentage of time allocated for copying to and/or from cache");
27
28/*----------------------------------------------------------------*/
29
30/*
31 * Glossary:
32 *
33 * oblock: index of an origin block
34 * cblock: index of a cache block
35 * promotion: movement of a block from origin to cache
36 * demotion: movement of a block from cache to origin
37 * migration: movement of a block between the origin and cache device,
38 * either direction
39 */
40
41/*----------------------------------------------------------------*/
42
43/*
44 * Represents a chunk of future work. 'input' allows continuations to pass
45 * values between themselves, typically error values.
46 */
47struct continuation {
48 struct work_struct ws;
49 blk_status_t input;
50};
51
52static inline void init_continuation(struct continuation *k,
53 void (*fn)(struct work_struct *))
54{
55 INIT_WORK(&k->ws, fn);
56 k->input = 0;
57}
58
59static inline void queue_continuation(struct workqueue_struct *wq,
60 struct continuation *k)
61{
62 queue_work(wq, &k->ws);
63}
64
65/*----------------------------------------------------------------*/
66
67/*
68 * The batcher collects together pieces of work that need a particular
69 * operation to occur before they can proceed (typically a commit).
70 */
71struct batcher {
72 /*
73 * The operation that everyone is waiting for.
74 */
75 blk_status_t (*commit_op)(void *context);
76 void *commit_context;
77
78 /*
79 * This is how bios should be issued once the commit op is complete
80 * (accounted_request).
81 */
82 void (*issue_op)(struct bio *bio, void *context);
83 void *issue_context;
84
85 /*
86 * Queued work gets put on here after commit.
87 */
88 struct workqueue_struct *wq;
89
90 spinlock_t lock;
91 struct list_head work_items;
92 struct bio_list bios;
93 struct work_struct commit_work;
94
95 bool commit_scheduled;
96};
97
98static void __commit(struct work_struct *_ws)
99{
100 struct batcher *b = container_of(_ws, struct batcher, commit_work);
101 blk_status_t r;
102 struct list_head work_items;
103 struct work_struct *ws, *tmp;
104 struct continuation *k;
105 struct bio *bio;
106 struct bio_list bios;
107
108 INIT_LIST_HEAD(&work_items);
109 bio_list_init(&bios);
110
111 /*
112 * We have to grab these before the commit_op to avoid a race
113 * condition.
114 */
115 spin_lock_irq(&b->lock);
116 list_splice_init(&b->work_items, &work_items);
117 bio_list_merge(&bios, &b->bios);
118 bio_list_init(&b->bios);
119 b->commit_scheduled = false;
120 spin_unlock_irq(&b->lock);
121
122 r = b->commit_op(b->commit_context);
123
124 list_for_each_entry_safe(ws, tmp, &work_items, entry) {
125 k = container_of(ws, struct continuation, ws);
126 k->input = r;
127 INIT_LIST_HEAD(&ws->entry); /* to avoid a WARN_ON */
128 queue_work(b->wq, ws);
129 }
130
131 while ((bio = bio_list_pop(&bios))) {
132 if (r) {
133 bio->bi_status = r;
134 bio_endio(bio);
135 } else
136 b->issue_op(bio, b->issue_context);
137 }
138}
139
140static void batcher_init(struct batcher *b,
141 blk_status_t (*commit_op)(void *),
142 void *commit_context,
143 void (*issue_op)(struct bio *bio, void *),
144 void *issue_context,
145 struct workqueue_struct *wq)
146{
147 b->commit_op = commit_op;
148 b->commit_context = commit_context;
149 b->issue_op = issue_op;
150 b->issue_context = issue_context;
151 b->wq = wq;
152
153 spin_lock_init(&b->lock);
154 INIT_LIST_HEAD(&b->work_items);
155 bio_list_init(&b->bios);
156 INIT_WORK(&b->commit_work, __commit);
157 b->commit_scheduled = false;
158}
159
160static void async_commit(struct batcher *b)
161{
162 queue_work(b->wq, &b->commit_work);
163}
164
165static void continue_after_commit(struct batcher *b, struct continuation *k)
166{
167 bool commit_scheduled;
168
169 spin_lock_irq(&b->lock);
170 commit_scheduled = b->commit_scheduled;
171 list_add_tail(&k->ws.entry, &b->work_items);
172 spin_unlock_irq(&b->lock);
173
174 if (commit_scheduled)
175 async_commit(b);
176}
177
178/*
179 * Bios are errored if commit failed.
180 */
181static void issue_after_commit(struct batcher *b, struct bio *bio)
182{
183 bool commit_scheduled;
184
185 spin_lock_irq(&b->lock);
186 commit_scheduled = b->commit_scheduled;
187 bio_list_add(&b->bios, bio);
188 spin_unlock_irq(&b->lock);
189
190 if (commit_scheduled)
191 async_commit(b);
192}
193
194/*
195 * Call this if some urgent work is waiting for the commit to complete.
196 */
197static void schedule_commit(struct batcher *b)
198{
199 bool immediate;
200
201 spin_lock_irq(&b->lock);
202 immediate = !list_empty(&b->work_items) || !bio_list_empty(&b->bios);
203 b->commit_scheduled = true;
204 spin_unlock_irq(&b->lock);
205
206 if (immediate)
207 async_commit(b);
208}
209
210/*
211 * There are a couple of places where we let a bio run, but want to do some
212 * work before calling its endio function. We do this by temporarily
213 * changing the endio fn.
214 */
215struct dm_hook_info {
216 bio_end_io_t *bi_end_io;
217};
218
219static void dm_hook_bio(struct dm_hook_info *h, struct bio *bio,
220 bio_end_io_t *bi_end_io, void *bi_private)
221{
222 h->bi_end_io = bio->bi_end_io;
223
224 bio->bi_end_io = bi_end_io;
225 bio->bi_private = bi_private;
226}
227
228static void dm_unhook_bio(struct dm_hook_info *h, struct bio *bio)
229{
230 bio->bi_end_io = h->bi_end_io;
231}
232
233/*----------------------------------------------------------------*/
234
235#define MIGRATION_POOL_SIZE 128
236#define COMMIT_PERIOD HZ
237#define MIGRATION_COUNT_WINDOW 10
238
239/*
240 * The block size of the device holding cache data must be
241 * between 32KB and 1GB.
242 */
243#define DATA_DEV_BLOCK_SIZE_MIN_SECTORS (32 * 1024 >> SECTOR_SHIFT)
244#define DATA_DEV_BLOCK_SIZE_MAX_SECTORS (1024 * 1024 * 1024 >> SECTOR_SHIFT)
245
246enum cache_metadata_mode {
247 CM_WRITE, /* metadata may be changed */
248 CM_READ_ONLY, /* metadata may not be changed */
249 CM_FAIL
250};
251
252enum cache_io_mode {
253 /*
254 * Data is written to cached blocks only. These blocks are marked
255 * dirty. If you lose the cache device you will lose data.
256 * Potential performance increase for both reads and writes.
257 */
258 CM_IO_WRITEBACK,
259
260 /*
261 * Data is written to both cache and origin. Blocks are never
262 * dirty. Potential performance benfit for reads only.
263 */
264 CM_IO_WRITETHROUGH,
265
266 /*
267 * A degraded mode useful for various cache coherency situations
268 * (eg, rolling back snapshots). Reads and writes always go to the
269 * origin. If a write goes to a cached oblock, then the cache
270 * block is invalidated.
271 */
272 CM_IO_PASSTHROUGH
273};
274
275struct cache_features {
276 enum cache_metadata_mode mode;
277 enum cache_io_mode io_mode;
278 unsigned metadata_version;
279 bool discard_passdown:1;
280};
281
282struct cache_stats {
283 atomic_t read_hit;
284 atomic_t read_miss;
285 atomic_t write_hit;
286 atomic_t write_miss;
287 atomic_t demotion;
288 atomic_t promotion;
289 atomic_t writeback;
290 atomic_t copies_avoided;
291 atomic_t cache_cell_clash;
292 atomic_t commit_count;
293 atomic_t discard_count;
294};
295
296struct cache {
297 struct dm_target *ti;
298 spinlock_t lock;
299
300 /*
301 * Fields for converting from sectors to blocks.
302 */
303 int sectors_per_block_shift;
304 sector_t sectors_per_block;
305
306 struct dm_cache_metadata *cmd;
307
308 /*
309 * Metadata is written to this device.
310 */
311 struct dm_dev *metadata_dev;
312
313 /*
314 * The slower of the two data devices. Typically a spindle.
315 */
316 struct dm_dev *origin_dev;
317
318 /*
319 * The faster of the two data devices. Typically an SSD.
320 */
321 struct dm_dev *cache_dev;
322
323 /*
324 * Size of the origin device in _complete_ blocks and native sectors.
325 */
326 dm_oblock_t origin_blocks;
327 sector_t origin_sectors;
328
329 /*
330 * Size of the cache device in blocks.
331 */
332 dm_cblock_t cache_size;
333
334 /*
335 * Invalidation fields.
336 */
337 spinlock_t invalidation_lock;
338 struct list_head invalidation_requests;
339
340 sector_t migration_threshold;
341 wait_queue_head_t migration_wait;
342 atomic_t nr_allocated_migrations;
343
344 /*
345 * The number of in flight migrations that are performing
346 * background io. eg, promotion, writeback.
347 */
348 atomic_t nr_io_migrations;
349
350 struct bio_list deferred_bios;
351
352 struct rw_semaphore quiesce_lock;
353
354 /*
355 * origin_blocks entries, discarded if set.
356 */
357 dm_dblock_t discard_nr_blocks;
358 unsigned long *discard_bitset;
359 uint32_t discard_block_size; /* a power of 2 times sectors per block */
360
361 /*
362 * Rather than reconstructing the table line for the status we just
363 * save it and regurgitate.
364 */
365 unsigned nr_ctr_args;
366 const char **ctr_args;
367
368 struct dm_kcopyd_client *copier;
369 struct work_struct deferred_bio_worker;
370 struct work_struct migration_worker;
371 struct workqueue_struct *wq;
372 struct delayed_work waker;
373 struct dm_bio_prison_v2 *prison;
374
375 /*
376 * cache_size entries, dirty if set
377 */
378 unsigned long *dirty_bitset;
379 atomic_t nr_dirty;
380
381 unsigned policy_nr_args;
382 struct dm_cache_policy *policy;
383
384 /*
385 * Cache features such as write-through.
386 */
387 struct cache_features features;
388
389 struct cache_stats stats;
390
391 bool need_tick_bio:1;
392 bool sized:1;
393 bool invalidate:1;
394 bool commit_requested:1;
395 bool loaded_mappings:1;
396 bool loaded_discards:1;
397
398 struct rw_semaphore background_work_lock;
399
400 struct batcher committer;
401 struct work_struct commit_ws;
402
403 struct dm_io_tracker tracker;
404
405 mempool_t migration_pool;
406
407 struct bio_set bs;
408};
409
410struct per_bio_data {
411 bool tick:1;
412 unsigned req_nr:2;
413 struct dm_bio_prison_cell_v2 *cell;
414 struct dm_hook_info hook_info;
415 sector_t len;
416};
417
418struct dm_cache_migration {
419 struct continuation k;
420 struct cache *cache;
421
422 struct policy_work *op;
423 struct bio *overwrite_bio;
424 struct dm_bio_prison_cell_v2 *cell;
425
426 dm_cblock_t invalidate_cblock;
427 dm_oblock_t invalidate_oblock;
428};
429
430/*----------------------------------------------------------------*/
431
432static bool writethrough_mode(struct cache *cache)
433{
434 return cache->features.io_mode == CM_IO_WRITETHROUGH;
435}
436
437static bool writeback_mode(struct cache *cache)
438{
439 return cache->features.io_mode == CM_IO_WRITEBACK;
440}
441
442static inline bool passthrough_mode(struct cache *cache)
443{
444 return unlikely(cache->features.io_mode == CM_IO_PASSTHROUGH);
445}
446
447/*----------------------------------------------------------------*/
448
449static void wake_deferred_bio_worker(struct cache *cache)
450{
451 queue_work(cache->wq, &cache->deferred_bio_worker);
452}
453
454static void wake_migration_worker(struct cache *cache)
455{
456 if (passthrough_mode(cache))
457 return;
458
459 queue_work(cache->wq, &cache->migration_worker);
460}
461
462/*----------------------------------------------------------------*/
463
464static struct dm_bio_prison_cell_v2 *alloc_prison_cell(struct cache *cache)
465{
466 return dm_bio_prison_alloc_cell_v2(cache->prison, GFP_NOIO);
467}
468
469static void free_prison_cell(struct cache *cache, struct dm_bio_prison_cell_v2 *cell)
470{
471 dm_bio_prison_free_cell_v2(cache->prison, cell);
472}
473
474static struct dm_cache_migration *alloc_migration(struct cache *cache)
475{
476 struct dm_cache_migration *mg;
477
478 mg = mempool_alloc(&cache->migration_pool, GFP_NOIO);
479
480 memset(mg, 0, sizeof(*mg));
481
482 mg->cache = cache;
483 atomic_inc(&cache->nr_allocated_migrations);
484
485 return mg;
486}
487
488static void free_migration(struct dm_cache_migration *mg)
489{
490 struct cache *cache = mg->cache;
491
492 if (atomic_dec_and_test(&cache->nr_allocated_migrations))
493 wake_up(&cache->migration_wait);
494
495 mempool_free(mg, &cache->migration_pool);
496}
497
498/*----------------------------------------------------------------*/
499
500static inline dm_oblock_t oblock_succ(dm_oblock_t b)
501{
502 return to_oblock(from_oblock(b) + 1ull);
503}
504
505static void build_key(dm_oblock_t begin, dm_oblock_t end, struct dm_cell_key_v2 *key)
506{
507 key->virtual = 0;
508 key->dev = 0;
509 key->block_begin = from_oblock(begin);
510 key->block_end = from_oblock(end);
511}
512
513/*
514 * We have two lock levels. Level 0, which is used to prevent WRITEs, and
515 * level 1 which prevents *both* READs and WRITEs.
516 */
517#define WRITE_LOCK_LEVEL 0
518#define READ_WRITE_LOCK_LEVEL 1
519
520static unsigned lock_level(struct bio *bio)
521{
522 return bio_data_dir(bio) == WRITE ?
523 WRITE_LOCK_LEVEL :
524 READ_WRITE_LOCK_LEVEL;
525}
526
527/*----------------------------------------------------------------
528 * Per bio data
529 *--------------------------------------------------------------*/
530
531static struct per_bio_data *get_per_bio_data(struct bio *bio)
532{
533 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
534 BUG_ON(!pb);
535 return pb;
536}
537
538static struct per_bio_data *init_per_bio_data(struct bio *bio)
539{
540 struct per_bio_data *pb = get_per_bio_data(bio);
541
542 pb->tick = false;
543 pb->req_nr = dm_bio_get_target_bio_nr(bio);
544 pb->cell = NULL;
545 pb->len = 0;
546
547 return pb;
548}
549
550/*----------------------------------------------------------------*/
551
552static void defer_bio(struct cache *cache, struct bio *bio)
553{
554 spin_lock_irq(&cache->lock);
555 bio_list_add(&cache->deferred_bios, bio);
556 spin_unlock_irq(&cache->lock);
557
558 wake_deferred_bio_worker(cache);
559}
560
561static void defer_bios(struct cache *cache, struct bio_list *bios)
562{
563 spin_lock_irq(&cache->lock);
564 bio_list_merge(&cache->deferred_bios, bios);
565 bio_list_init(bios);
566 spin_unlock_irq(&cache->lock);
567
568 wake_deferred_bio_worker(cache);
569}
570
571/*----------------------------------------------------------------*/
572
573static bool bio_detain_shared(struct cache *cache, dm_oblock_t oblock, struct bio *bio)
574{
575 bool r;
576 struct per_bio_data *pb;
577 struct dm_cell_key_v2 key;
578 dm_oblock_t end = to_oblock(from_oblock(oblock) + 1ULL);
579 struct dm_bio_prison_cell_v2 *cell_prealloc, *cell;
580
581 cell_prealloc = alloc_prison_cell(cache); /* FIXME: allow wait if calling from worker */
582
583 build_key(oblock, end, &key);
584 r = dm_cell_get_v2(cache->prison, &key, lock_level(bio), bio, cell_prealloc, &cell);
585 if (!r) {
586 /*
587 * Failed to get the lock.
588 */
589 free_prison_cell(cache, cell_prealloc);
590 return r;
591 }
592
593 if (cell != cell_prealloc)
594 free_prison_cell(cache, cell_prealloc);
595
596 pb = get_per_bio_data(bio);
597 pb->cell = cell;
598
599 return r;
600}
601
602/*----------------------------------------------------------------*/
603
604static bool is_dirty(struct cache *cache, dm_cblock_t b)
605{
606 return test_bit(from_cblock(b), cache->dirty_bitset);
607}
608
609static void set_dirty(struct cache *cache, dm_cblock_t cblock)
610{
611 if (!test_and_set_bit(from_cblock(cblock), cache->dirty_bitset)) {
612 atomic_inc(&cache->nr_dirty);
613 policy_set_dirty(cache->policy, cblock);
614 }
615}
616
617/*
618 * These two are called when setting after migrations to force the policy
619 * and dirty bitset to be in sync.
620 */
621static void force_set_dirty(struct cache *cache, dm_cblock_t cblock)
622{
623 if (!test_and_set_bit(from_cblock(cblock), cache->dirty_bitset))
624 atomic_inc(&cache->nr_dirty);
625 policy_set_dirty(cache->policy, cblock);
626}
627
628static void force_clear_dirty(struct cache *cache, dm_cblock_t cblock)
629{
630 if (test_and_clear_bit(from_cblock(cblock), cache->dirty_bitset)) {
631 if (atomic_dec_return(&cache->nr_dirty) == 0)
632 dm_table_event(cache->ti->table);
633 }
634
635 policy_clear_dirty(cache->policy, cblock);
636}
637
638/*----------------------------------------------------------------*/
639
640static bool block_size_is_power_of_two(struct cache *cache)
641{
642 return cache->sectors_per_block_shift >= 0;
643}
644
645static dm_block_t block_div(dm_block_t b, uint32_t n)
646{
647 do_div(b, n);
648
649 return b;
650}
651
652static dm_block_t oblocks_per_dblock(struct cache *cache)
653{
654 dm_block_t oblocks = cache->discard_block_size;
655
656 if (block_size_is_power_of_two(cache))
657 oblocks >>= cache->sectors_per_block_shift;
658 else
659 oblocks = block_div(oblocks, cache->sectors_per_block);
660
661 return oblocks;
662}
663
664static dm_dblock_t oblock_to_dblock(struct cache *cache, dm_oblock_t oblock)
665{
666 return to_dblock(block_div(from_oblock(oblock),
667 oblocks_per_dblock(cache)));
668}
669
670static void set_discard(struct cache *cache, dm_dblock_t b)
671{
672 BUG_ON(from_dblock(b) >= from_dblock(cache->discard_nr_blocks));
673 atomic_inc(&cache->stats.discard_count);
674
675 spin_lock_irq(&cache->lock);
676 set_bit(from_dblock(b), cache->discard_bitset);
677 spin_unlock_irq(&cache->lock);
678}
679
680static void clear_discard(struct cache *cache, dm_dblock_t b)
681{
682 spin_lock_irq(&cache->lock);
683 clear_bit(from_dblock(b), cache->discard_bitset);
684 spin_unlock_irq(&cache->lock);
685}
686
687static bool is_discarded(struct cache *cache, dm_dblock_t b)
688{
689 int r;
690 spin_lock_irq(&cache->lock);
691 r = test_bit(from_dblock(b), cache->discard_bitset);
692 spin_unlock_irq(&cache->lock);
693
694 return r;
695}
696
697static bool is_discarded_oblock(struct cache *cache, dm_oblock_t b)
698{
699 int r;
700 spin_lock_irq(&cache->lock);
701 r = test_bit(from_dblock(oblock_to_dblock(cache, b)),
702 cache->discard_bitset);
703 spin_unlock_irq(&cache->lock);
704
705 return r;
706}
707
708/*----------------------------------------------------------------
709 * Remapping
710 *--------------------------------------------------------------*/
711static void remap_to_origin(struct cache *cache, struct bio *bio)
712{
713 bio_set_dev(bio, cache->origin_dev->bdev);
714}
715
716static void remap_to_cache(struct cache *cache, struct bio *bio,
717 dm_cblock_t cblock)
718{
719 sector_t bi_sector = bio->bi_iter.bi_sector;
720 sector_t block = from_cblock(cblock);
721
722 bio_set_dev(bio, cache->cache_dev->bdev);
723 if (!block_size_is_power_of_two(cache))
724 bio->bi_iter.bi_sector =
725 (block * cache->sectors_per_block) +
726 sector_div(bi_sector, cache->sectors_per_block);
727 else
728 bio->bi_iter.bi_sector =
729 (block << cache->sectors_per_block_shift) |
730 (bi_sector & (cache->sectors_per_block - 1));
731}
732
733static void check_if_tick_bio_needed(struct cache *cache, struct bio *bio)
734{
735 struct per_bio_data *pb;
736
737 spin_lock_irq(&cache->lock);
738 if (cache->need_tick_bio && !op_is_flush(bio->bi_opf) &&
739 bio_op(bio) != REQ_OP_DISCARD) {
740 pb = get_per_bio_data(bio);
741 pb->tick = true;
742 cache->need_tick_bio = false;
743 }
744 spin_unlock_irq(&cache->lock);
745}
746
747static void remap_to_origin_clear_discard(struct cache *cache, struct bio *bio,
748 dm_oblock_t oblock)
749{
750 // FIXME: check_if_tick_bio_needed() is called way too much through this interface
751 check_if_tick_bio_needed(cache, bio);
752 remap_to_origin(cache, bio);
753 if (bio_data_dir(bio) == WRITE)
754 clear_discard(cache, oblock_to_dblock(cache, oblock));
755}
756
757static void remap_to_cache_dirty(struct cache *cache, struct bio *bio,
758 dm_oblock_t oblock, dm_cblock_t cblock)
759{
760 check_if_tick_bio_needed(cache, bio);
761 remap_to_cache(cache, bio, cblock);
762 if (bio_data_dir(bio) == WRITE) {
763 set_dirty(cache, cblock);
764 clear_discard(cache, oblock_to_dblock(cache, oblock));
765 }
766}
767
768static dm_oblock_t get_bio_block(struct cache *cache, struct bio *bio)
769{
770 sector_t block_nr = bio->bi_iter.bi_sector;
771
772 if (!block_size_is_power_of_two(cache))
773 (void) sector_div(block_nr, cache->sectors_per_block);
774 else
775 block_nr >>= cache->sectors_per_block_shift;
776
777 return to_oblock(block_nr);
778}
779
780static bool accountable_bio(struct cache *cache, struct bio *bio)
781{
782 return bio_op(bio) != REQ_OP_DISCARD;
783}
784
785static void accounted_begin(struct cache *cache, struct bio *bio)
786{
787 struct per_bio_data *pb;
788
789 if (accountable_bio(cache, bio)) {
790 pb = get_per_bio_data(bio);
791 pb->len = bio_sectors(bio);
792 dm_iot_io_begin(&cache->tracker, pb->len);
793 }
794}
795
796static void accounted_complete(struct cache *cache, struct bio *bio)
797{
798 struct per_bio_data *pb = get_per_bio_data(bio);
799
800 dm_iot_io_end(&cache->tracker, pb->len);
801}
802
803static void accounted_request(struct cache *cache, struct bio *bio)
804{
805 accounted_begin(cache, bio);
806 dm_submit_bio_remap(bio, NULL);
807}
808
809static void issue_op(struct bio *bio, void *context)
810{
811 struct cache *cache = context;
812 accounted_request(cache, bio);
813}
814
815/*
816 * When running in writethrough mode we need to send writes to clean blocks
817 * to both the cache and origin devices. Clone the bio and send them in parallel.
818 */
819static void remap_to_origin_and_cache(struct cache *cache, struct bio *bio,
820 dm_oblock_t oblock, dm_cblock_t cblock)
821{
822 struct bio *origin_bio = bio_alloc_clone(cache->origin_dev->bdev, bio,
823 GFP_NOIO, &cache->bs);
824
825 BUG_ON(!origin_bio);
826
827 bio_chain(origin_bio, bio);
828
829 if (bio_data_dir(origin_bio) == WRITE)
830 clear_discard(cache, oblock_to_dblock(cache, oblock));
831 submit_bio(origin_bio);
832
833 remap_to_cache(cache, bio, cblock);
834}
835
836/*----------------------------------------------------------------
837 * Failure modes
838 *--------------------------------------------------------------*/
839static enum cache_metadata_mode get_cache_mode(struct cache *cache)
840{
841 return cache->features.mode;
842}
843
844static const char *cache_device_name(struct cache *cache)
845{
846 return dm_table_device_name(cache->ti->table);
847}
848
849static void notify_mode_switch(struct cache *cache, enum cache_metadata_mode mode)
850{
851 const char *descs[] = {
852 "write",
853 "read-only",
854 "fail"
855 };
856
857 dm_table_event(cache->ti->table);
858 DMINFO("%s: switching cache to %s mode",
859 cache_device_name(cache), descs[(int)mode]);
860}
861
862static void set_cache_mode(struct cache *cache, enum cache_metadata_mode new_mode)
863{
864 bool needs_check;
865 enum cache_metadata_mode old_mode = get_cache_mode(cache);
866
867 if (dm_cache_metadata_needs_check(cache->cmd, &needs_check)) {
868 DMERR("%s: unable to read needs_check flag, setting failure mode.",
869 cache_device_name(cache));
870 new_mode = CM_FAIL;
871 }
872
873 if (new_mode == CM_WRITE && needs_check) {
874 DMERR("%s: unable to switch cache to write mode until repaired.",
875 cache_device_name(cache));
876 if (old_mode != new_mode)
877 new_mode = old_mode;
878 else
879 new_mode = CM_READ_ONLY;
880 }
881
882 /* Never move out of fail mode */
883 if (old_mode == CM_FAIL)
884 new_mode = CM_FAIL;
885
886 switch (new_mode) {
887 case CM_FAIL:
888 case CM_READ_ONLY:
889 dm_cache_metadata_set_read_only(cache->cmd);
890 break;
891
892 case CM_WRITE:
893 dm_cache_metadata_set_read_write(cache->cmd);
894 break;
895 }
896
897 cache->features.mode = new_mode;
898
899 if (new_mode != old_mode)
900 notify_mode_switch(cache, new_mode);
901}
902
903static void abort_transaction(struct cache *cache)
904{
905 const char *dev_name = cache_device_name(cache);
906
907 if (get_cache_mode(cache) >= CM_READ_ONLY)
908 return;
909
910 DMERR_LIMIT("%s: aborting current metadata transaction", dev_name);
911 if (dm_cache_metadata_abort(cache->cmd)) {
912 DMERR("%s: failed to abort metadata transaction", dev_name);
913 set_cache_mode(cache, CM_FAIL);
914 }
915
916 if (dm_cache_metadata_set_needs_check(cache->cmd)) {
917 DMERR("%s: failed to set 'needs_check' flag in metadata", dev_name);
918 set_cache_mode(cache, CM_FAIL);
919 }
920}
921
922static void metadata_operation_failed(struct cache *cache, const char *op, int r)
923{
924 DMERR_LIMIT("%s: metadata operation '%s' failed: error = %d",
925 cache_device_name(cache), op, r);
926 abort_transaction(cache);
927 set_cache_mode(cache, CM_READ_ONLY);
928}
929
930/*----------------------------------------------------------------*/
931
932static void load_stats(struct cache *cache)
933{
934 struct dm_cache_statistics stats;
935
936 dm_cache_metadata_get_stats(cache->cmd, &stats);
937 atomic_set(&cache->stats.read_hit, stats.read_hits);
938 atomic_set(&cache->stats.read_miss, stats.read_misses);
939 atomic_set(&cache->stats.write_hit, stats.write_hits);
940 atomic_set(&cache->stats.write_miss, stats.write_misses);
941}
942
943static void save_stats(struct cache *cache)
944{
945 struct dm_cache_statistics stats;
946
947 if (get_cache_mode(cache) >= CM_READ_ONLY)
948 return;
949
950 stats.read_hits = atomic_read(&cache->stats.read_hit);
951 stats.read_misses = atomic_read(&cache->stats.read_miss);
952 stats.write_hits = atomic_read(&cache->stats.write_hit);
953 stats.write_misses = atomic_read(&cache->stats.write_miss);
954
955 dm_cache_metadata_set_stats(cache->cmd, &stats);
956}
957
958static void update_stats(struct cache_stats *stats, enum policy_operation op)
959{
960 switch (op) {
961 case POLICY_PROMOTE:
962 atomic_inc(&stats->promotion);
963 break;
964
965 case POLICY_DEMOTE:
966 atomic_inc(&stats->demotion);
967 break;
968
969 case POLICY_WRITEBACK:
970 atomic_inc(&stats->writeback);
971 break;
972 }
973}
974
975/*----------------------------------------------------------------
976 * Migration processing
977 *
978 * Migration covers moving data from the origin device to the cache, or
979 * vice versa.
980 *--------------------------------------------------------------*/
981
982static void inc_io_migrations(struct cache *cache)
983{
984 atomic_inc(&cache->nr_io_migrations);
985}
986
987static void dec_io_migrations(struct cache *cache)
988{
989 atomic_dec(&cache->nr_io_migrations);
990}
991
992static bool discard_or_flush(struct bio *bio)
993{
994 return bio_op(bio) == REQ_OP_DISCARD || op_is_flush(bio->bi_opf);
995}
996
997static void calc_discard_block_range(struct cache *cache, struct bio *bio,
998 dm_dblock_t *b, dm_dblock_t *e)
999{
1000 sector_t sb = bio->bi_iter.bi_sector;
1001 sector_t se = bio_end_sector(bio);
1002
1003 *b = to_dblock(dm_sector_div_up(sb, cache->discard_block_size));
1004
1005 if (se - sb < cache->discard_block_size)
1006 *e = *b;
1007 else
1008 *e = to_dblock(block_div(se, cache->discard_block_size));
1009}
1010
1011/*----------------------------------------------------------------*/
1012
1013static void prevent_background_work(struct cache *cache)
1014{
1015 lockdep_off();
1016 down_write(&cache->background_work_lock);
1017 lockdep_on();
1018}
1019
1020static void allow_background_work(struct cache *cache)
1021{
1022 lockdep_off();
1023 up_write(&cache->background_work_lock);
1024 lockdep_on();
1025}
1026
1027static bool background_work_begin(struct cache *cache)
1028{
1029 bool r;
1030
1031 lockdep_off();
1032 r = down_read_trylock(&cache->background_work_lock);
1033 lockdep_on();
1034
1035 return r;
1036}
1037
1038static void background_work_end(struct cache *cache)
1039{
1040 lockdep_off();
1041 up_read(&cache->background_work_lock);
1042 lockdep_on();
1043}
1044
1045/*----------------------------------------------------------------*/
1046
1047static bool bio_writes_complete_block(struct cache *cache, struct bio *bio)
1048{
1049 return (bio_data_dir(bio) == WRITE) &&
1050 (bio->bi_iter.bi_size == (cache->sectors_per_block << SECTOR_SHIFT));
1051}
1052
1053static bool optimisable_bio(struct cache *cache, struct bio *bio, dm_oblock_t block)
1054{
1055 return writeback_mode(cache) &&
1056 (is_discarded_oblock(cache, block) || bio_writes_complete_block(cache, bio));
1057}
1058
1059static void quiesce(struct dm_cache_migration *mg,
1060 void (*continuation)(struct work_struct *))
1061{
1062 init_continuation(&mg->k, continuation);
1063 dm_cell_quiesce_v2(mg->cache->prison, mg->cell, &mg->k.ws);
1064}
1065
1066static struct dm_cache_migration *ws_to_mg(struct work_struct *ws)
1067{
1068 struct continuation *k = container_of(ws, struct continuation, ws);
1069 return container_of(k, struct dm_cache_migration, k);
1070}
1071
1072static void copy_complete(int read_err, unsigned long write_err, void *context)
1073{
1074 struct dm_cache_migration *mg = container_of(context, struct dm_cache_migration, k);
1075
1076 if (read_err || write_err)
1077 mg->k.input = BLK_STS_IOERR;
1078
1079 queue_continuation(mg->cache->wq, &mg->k);
1080}
1081
1082static void copy(struct dm_cache_migration *mg, bool promote)
1083{
1084 struct dm_io_region o_region, c_region;
1085 struct cache *cache = mg->cache;
1086
1087 o_region.bdev = cache->origin_dev->bdev;
1088 o_region.sector = from_oblock(mg->op->oblock) * cache->sectors_per_block;
1089 o_region.count = cache->sectors_per_block;
1090
1091 c_region.bdev = cache->cache_dev->bdev;
1092 c_region.sector = from_cblock(mg->op->cblock) * cache->sectors_per_block;
1093 c_region.count = cache->sectors_per_block;
1094
1095 if (promote)
1096 dm_kcopyd_copy(cache->copier, &o_region, 1, &c_region, 0, copy_complete, &mg->k);
1097 else
1098 dm_kcopyd_copy(cache->copier, &c_region, 1, &o_region, 0, copy_complete, &mg->k);
1099}
1100
1101static void bio_drop_shared_lock(struct cache *cache, struct bio *bio)
1102{
1103 struct per_bio_data *pb = get_per_bio_data(bio);
1104
1105 if (pb->cell && dm_cell_put_v2(cache->prison, pb->cell))
1106 free_prison_cell(cache, pb->cell);
1107 pb->cell = NULL;
1108}
1109
1110static void overwrite_endio(struct bio *bio)
1111{
1112 struct dm_cache_migration *mg = bio->bi_private;
1113 struct cache *cache = mg->cache;
1114 struct per_bio_data *pb = get_per_bio_data(bio);
1115
1116 dm_unhook_bio(&pb->hook_info, bio);
1117
1118 if (bio->bi_status)
1119 mg->k.input = bio->bi_status;
1120
1121 queue_continuation(cache->wq, &mg->k);
1122}
1123
1124static void overwrite(struct dm_cache_migration *mg,
1125 void (*continuation)(struct work_struct *))
1126{
1127 struct bio *bio = mg->overwrite_bio;
1128 struct per_bio_data *pb = get_per_bio_data(bio);
1129
1130 dm_hook_bio(&pb->hook_info, bio, overwrite_endio, mg);
1131
1132 /*
1133 * The overwrite bio is part of the copy operation, as such it does
1134 * not set/clear discard or dirty flags.
1135 */
1136 if (mg->op->op == POLICY_PROMOTE)
1137 remap_to_cache(mg->cache, bio, mg->op->cblock);
1138 else
1139 remap_to_origin(mg->cache, bio);
1140
1141 init_continuation(&mg->k, continuation);
1142 accounted_request(mg->cache, bio);
1143}
1144
1145/*
1146 * Migration steps:
1147 *
1148 * 1) exclusive lock preventing WRITEs
1149 * 2) quiesce
1150 * 3) copy or issue overwrite bio
1151 * 4) upgrade to exclusive lock preventing READs and WRITEs
1152 * 5) quiesce
1153 * 6) update metadata and commit
1154 * 7) unlock
1155 */
1156static void mg_complete(struct dm_cache_migration *mg, bool success)
1157{
1158 struct bio_list bios;
1159 struct cache *cache = mg->cache;
1160 struct policy_work *op = mg->op;
1161 dm_cblock_t cblock = op->cblock;
1162
1163 if (success)
1164 update_stats(&cache->stats, op->op);
1165
1166 switch (op->op) {
1167 case POLICY_PROMOTE:
1168 clear_discard(cache, oblock_to_dblock(cache, op->oblock));
1169 policy_complete_background_work(cache->policy, op, success);
1170
1171 if (mg->overwrite_bio) {
1172 if (success)
1173 force_set_dirty(cache, cblock);
1174 else if (mg->k.input)
1175 mg->overwrite_bio->bi_status = mg->k.input;
1176 else
1177 mg->overwrite_bio->bi_status = BLK_STS_IOERR;
1178 bio_endio(mg->overwrite_bio);
1179 } else {
1180 if (success)
1181 force_clear_dirty(cache, cblock);
1182 dec_io_migrations(cache);
1183 }
1184 break;
1185
1186 case POLICY_DEMOTE:
1187 /*
1188 * We clear dirty here to update the nr_dirty counter.
1189 */
1190 if (success)
1191 force_clear_dirty(cache, cblock);
1192 policy_complete_background_work(cache->policy, op, success);
1193 dec_io_migrations(cache);
1194 break;
1195
1196 case POLICY_WRITEBACK:
1197 if (success)
1198 force_clear_dirty(cache, cblock);
1199 policy_complete_background_work(cache->policy, op, success);
1200 dec_io_migrations(cache);
1201 break;
1202 }
1203
1204 bio_list_init(&bios);
1205 if (mg->cell) {
1206 if (dm_cell_unlock_v2(cache->prison, mg->cell, &bios))
1207 free_prison_cell(cache, mg->cell);
1208 }
1209
1210 free_migration(mg);
1211 defer_bios(cache, &bios);
1212 wake_migration_worker(cache);
1213
1214 background_work_end(cache);
1215}
1216
1217static void mg_success(struct work_struct *ws)
1218{
1219 struct dm_cache_migration *mg = ws_to_mg(ws);
1220 mg_complete(mg, mg->k.input == 0);
1221}
1222
1223static void mg_update_metadata(struct work_struct *ws)
1224{
1225 int r;
1226 struct dm_cache_migration *mg = ws_to_mg(ws);
1227 struct cache *cache = mg->cache;
1228 struct policy_work *op = mg->op;
1229
1230 switch (op->op) {
1231 case POLICY_PROMOTE:
1232 r = dm_cache_insert_mapping(cache->cmd, op->cblock, op->oblock);
1233 if (r) {
1234 DMERR_LIMIT("%s: migration failed; couldn't insert mapping",
1235 cache_device_name(cache));
1236 metadata_operation_failed(cache, "dm_cache_insert_mapping", r);
1237
1238 mg_complete(mg, false);
1239 return;
1240 }
1241 mg_complete(mg, true);
1242 break;
1243
1244 case POLICY_DEMOTE:
1245 r = dm_cache_remove_mapping(cache->cmd, op->cblock);
1246 if (r) {
1247 DMERR_LIMIT("%s: migration failed; couldn't update on disk metadata",
1248 cache_device_name(cache));
1249 metadata_operation_failed(cache, "dm_cache_remove_mapping", r);
1250
1251 mg_complete(mg, false);
1252 return;
1253 }
1254
1255 /*
1256 * It would be nice if we only had to commit when a REQ_FLUSH
1257 * comes through. But there's one scenario that we have to
1258 * look out for:
1259 *
1260 * - vblock x in a cache block
1261 * - domotion occurs
1262 * - cache block gets reallocated and over written
1263 * - crash
1264 *
1265 * When we recover, because there was no commit the cache will
1266 * rollback to having the data for vblock x in the cache block.
1267 * But the cache block has since been overwritten, so it'll end
1268 * up pointing to data that was never in 'x' during the history
1269 * of the device.
1270 *
1271 * To avoid this issue we require a commit as part of the
1272 * demotion operation.
1273 */
1274 init_continuation(&mg->k, mg_success);
1275 continue_after_commit(&cache->committer, &mg->k);
1276 schedule_commit(&cache->committer);
1277 break;
1278
1279 case POLICY_WRITEBACK:
1280 mg_complete(mg, true);
1281 break;
1282 }
1283}
1284
1285static void mg_update_metadata_after_copy(struct work_struct *ws)
1286{
1287 struct dm_cache_migration *mg = ws_to_mg(ws);
1288
1289 /*
1290 * Did the copy succeed?
1291 */
1292 if (mg->k.input)
1293 mg_complete(mg, false);
1294 else
1295 mg_update_metadata(ws);
1296}
1297
1298static void mg_upgrade_lock(struct work_struct *ws)
1299{
1300 int r;
1301 struct dm_cache_migration *mg = ws_to_mg(ws);
1302
1303 /*
1304 * Did the copy succeed?
1305 */
1306 if (mg->k.input)
1307 mg_complete(mg, false);
1308
1309 else {
1310 /*
1311 * Now we want the lock to prevent both reads and writes.
1312 */
1313 r = dm_cell_lock_promote_v2(mg->cache->prison, mg->cell,
1314 READ_WRITE_LOCK_LEVEL);
1315 if (r < 0)
1316 mg_complete(mg, false);
1317
1318 else if (r)
1319 quiesce(mg, mg_update_metadata);
1320
1321 else
1322 mg_update_metadata(ws);
1323 }
1324}
1325
1326static void mg_full_copy(struct work_struct *ws)
1327{
1328 struct dm_cache_migration *mg = ws_to_mg(ws);
1329 struct cache *cache = mg->cache;
1330 struct policy_work *op = mg->op;
1331 bool is_policy_promote = (op->op == POLICY_PROMOTE);
1332
1333 if ((!is_policy_promote && !is_dirty(cache, op->cblock)) ||
1334 is_discarded_oblock(cache, op->oblock)) {
1335 mg_upgrade_lock(ws);
1336 return;
1337 }
1338
1339 init_continuation(&mg->k, mg_upgrade_lock);
1340 copy(mg, is_policy_promote);
1341}
1342
1343static void mg_copy(struct work_struct *ws)
1344{
1345 struct dm_cache_migration *mg = ws_to_mg(ws);
1346
1347 if (mg->overwrite_bio) {
1348 /*
1349 * No exclusive lock was held when we last checked if the bio
1350 * was optimisable. So we have to check again in case things
1351 * have changed (eg, the block may no longer be discarded).
1352 */
1353 if (!optimisable_bio(mg->cache, mg->overwrite_bio, mg->op->oblock)) {
1354 /*
1355 * Fallback to a real full copy after doing some tidying up.
1356 */
1357 bool rb = bio_detain_shared(mg->cache, mg->op->oblock, mg->overwrite_bio);
1358 BUG_ON(rb); /* An exclussive lock must _not_ be held for this block */
1359 mg->overwrite_bio = NULL;
1360 inc_io_migrations(mg->cache);
1361 mg_full_copy(ws);
1362 return;
1363 }
1364
1365 /*
1366 * It's safe to do this here, even though it's new data
1367 * because all IO has been locked out of the block.
1368 *
1369 * mg_lock_writes() already took READ_WRITE_LOCK_LEVEL
1370 * so _not_ using mg_upgrade_lock() as continutation.
1371 */
1372 overwrite(mg, mg_update_metadata_after_copy);
1373
1374 } else
1375 mg_full_copy(ws);
1376}
1377
1378static int mg_lock_writes(struct dm_cache_migration *mg)
1379{
1380 int r;
1381 struct dm_cell_key_v2 key;
1382 struct cache *cache = mg->cache;
1383 struct dm_bio_prison_cell_v2 *prealloc;
1384
1385 prealloc = alloc_prison_cell(cache);
1386
1387 /*
1388 * Prevent writes to the block, but allow reads to continue.
1389 * Unless we're using an overwrite bio, in which case we lock
1390 * everything.
1391 */
1392 build_key(mg->op->oblock, oblock_succ(mg->op->oblock), &key);
1393 r = dm_cell_lock_v2(cache->prison, &key,
1394 mg->overwrite_bio ? READ_WRITE_LOCK_LEVEL : WRITE_LOCK_LEVEL,
1395 prealloc, &mg->cell);
1396 if (r < 0) {
1397 free_prison_cell(cache, prealloc);
1398 mg_complete(mg, false);
1399 return r;
1400 }
1401
1402 if (mg->cell != prealloc)
1403 free_prison_cell(cache, prealloc);
1404
1405 if (r == 0)
1406 mg_copy(&mg->k.ws);
1407 else
1408 quiesce(mg, mg_copy);
1409
1410 return 0;
1411}
1412
1413static int mg_start(struct cache *cache, struct policy_work *op, struct bio *bio)
1414{
1415 struct dm_cache_migration *mg;
1416
1417 if (!background_work_begin(cache)) {
1418 policy_complete_background_work(cache->policy, op, false);
1419 return -EPERM;
1420 }
1421
1422 mg = alloc_migration(cache);
1423
1424 mg->op = op;
1425 mg->overwrite_bio = bio;
1426
1427 if (!bio)
1428 inc_io_migrations(cache);
1429
1430 return mg_lock_writes(mg);
1431}
1432
1433/*----------------------------------------------------------------
1434 * invalidation processing
1435 *--------------------------------------------------------------*/
1436
1437static void invalidate_complete(struct dm_cache_migration *mg, bool success)
1438{
1439 struct bio_list bios;
1440 struct cache *cache = mg->cache;
1441
1442 bio_list_init(&bios);
1443 if (dm_cell_unlock_v2(cache->prison, mg->cell, &bios))
1444 free_prison_cell(cache, mg->cell);
1445
1446 if (!success && mg->overwrite_bio)
1447 bio_io_error(mg->overwrite_bio);
1448
1449 free_migration(mg);
1450 defer_bios(cache, &bios);
1451
1452 background_work_end(cache);
1453}
1454
1455static void invalidate_completed(struct work_struct *ws)
1456{
1457 struct dm_cache_migration *mg = ws_to_mg(ws);
1458 invalidate_complete(mg, !mg->k.input);
1459}
1460
1461static int invalidate_cblock(struct cache *cache, dm_cblock_t cblock)
1462{
1463 int r = policy_invalidate_mapping(cache->policy, cblock);
1464 if (!r) {
1465 r = dm_cache_remove_mapping(cache->cmd, cblock);
1466 if (r) {
1467 DMERR_LIMIT("%s: invalidation failed; couldn't update on disk metadata",
1468 cache_device_name(cache));
1469 metadata_operation_failed(cache, "dm_cache_remove_mapping", r);
1470 }
1471
1472 } else if (r == -ENODATA) {
1473 /*
1474 * Harmless, already unmapped.
1475 */
1476 r = 0;
1477
1478 } else
1479 DMERR("%s: policy_invalidate_mapping failed", cache_device_name(cache));
1480
1481 return r;
1482}
1483
1484static void invalidate_remove(struct work_struct *ws)
1485{
1486 int r;
1487 struct dm_cache_migration *mg = ws_to_mg(ws);
1488 struct cache *cache = mg->cache;
1489
1490 r = invalidate_cblock(cache, mg->invalidate_cblock);
1491 if (r) {
1492 invalidate_complete(mg, false);
1493 return;
1494 }
1495
1496 init_continuation(&mg->k, invalidate_completed);
1497 continue_after_commit(&cache->committer, &mg->k);
1498 remap_to_origin_clear_discard(cache, mg->overwrite_bio, mg->invalidate_oblock);
1499 mg->overwrite_bio = NULL;
1500 schedule_commit(&cache->committer);
1501}
1502
1503static int invalidate_lock(struct dm_cache_migration *mg)
1504{
1505 int r;
1506 struct dm_cell_key_v2 key;
1507 struct cache *cache = mg->cache;
1508 struct dm_bio_prison_cell_v2 *prealloc;
1509
1510 prealloc = alloc_prison_cell(cache);
1511
1512 build_key(mg->invalidate_oblock, oblock_succ(mg->invalidate_oblock), &key);
1513 r = dm_cell_lock_v2(cache->prison, &key,
1514 READ_WRITE_LOCK_LEVEL, prealloc, &mg->cell);
1515 if (r < 0) {
1516 free_prison_cell(cache, prealloc);
1517 invalidate_complete(mg, false);
1518 return r;
1519 }
1520
1521 if (mg->cell != prealloc)
1522 free_prison_cell(cache, prealloc);
1523
1524 if (r)
1525 quiesce(mg, invalidate_remove);
1526
1527 else {
1528 /*
1529 * We can't call invalidate_remove() directly here because we
1530 * might still be in request context.
1531 */
1532 init_continuation(&mg->k, invalidate_remove);
1533 queue_work(cache->wq, &mg->k.ws);
1534 }
1535
1536 return 0;
1537}
1538
1539static int invalidate_start(struct cache *cache, dm_cblock_t cblock,
1540 dm_oblock_t oblock, struct bio *bio)
1541{
1542 struct dm_cache_migration *mg;
1543
1544 if (!background_work_begin(cache))
1545 return -EPERM;
1546
1547 mg = alloc_migration(cache);
1548
1549 mg->overwrite_bio = bio;
1550 mg->invalidate_cblock = cblock;
1551 mg->invalidate_oblock = oblock;
1552
1553 return invalidate_lock(mg);
1554}
1555
1556/*----------------------------------------------------------------
1557 * bio processing
1558 *--------------------------------------------------------------*/
1559
1560enum busy {
1561 IDLE,
1562 BUSY
1563};
1564
1565static enum busy spare_migration_bandwidth(struct cache *cache)
1566{
1567 bool idle = dm_iot_idle_for(&cache->tracker, HZ);
1568 sector_t current_volume = (atomic_read(&cache->nr_io_migrations) + 1) *
1569 cache->sectors_per_block;
1570
1571 if (idle && current_volume <= cache->migration_threshold)
1572 return IDLE;
1573 else
1574 return BUSY;
1575}
1576
1577static void inc_hit_counter(struct cache *cache, struct bio *bio)
1578{
1579 atomic_inc(bio_data_dir(bio) == READ ?
1580 &cache->stats.read_hit : &cache->stats.write_hit);
1581}
1582
1583static void inc_miss_counter(struct cache *cache, struct bio *bio)
1584{
1585 atomic_inc(bio_data_dir(bio) == READ ?
1586 &cache->stats.read_miss : &cache->stats.write_miss);
1587}
1588
1589/*----------------------------------------------------------------*/
1590
1591static int map_bio(struct cache *cache, struct bio *bio, dm_oblock_t block,
1592 bool *commit_needed)
1593{
1594 int r, data_dir;
1595 bool rb, background_queued;
1596 dm_cblock_t cblock;
1597
1598 *commit_needed = false;
1599
1600 rb = bio_detain_shared(cache, block, bio);
1601 if (!rb) {
1602 /*
1603 * An exclusive lock is held for this block, so we have to
1604 * wait. We set the commit_needed flag so the current
1605 * transaction will be committed asap, allowing this lock
1606 * to be dropped.
1607 */
1608 *commit_needed = true;
1609 return DM_MAPIO_SUBMITTED;
1610 }
1611
1612 data_dir = bio_data_dir(bio);
1613
1614 if (optimisable_bio(cache, bio, block)) {
1615 struct policy_work *op = NULL;
1616
1617 r = policy_lookup_with_work(cache->policy, block, &cblock, data_dir, true, &op);
1618 if (unlikely(r && r != -ENOENT)) {
1619 DMERR_LIMIT("%s: policy_lookup_with_work() failed with r = %d",
1620 cache_device_name(cache), r);
1621 bio_io_error(bio);
1622 return DM_MAPIO_SUBMITTED;
1623 }
1624
1625 if (r == -ENOENT && op) {
1626 bio_drop_shared_lock(cache, bio);
1627 BUG_ON(op->op != POLICY_PROMOTE);
1628 mg_start(cache, op, bio);
1629 return DM_MAPIO_SUBMITTED;
1630 }
1631 } else {
1632 r = policy_lookup(cache->policy, block, &cblock, data_dir, false, &background_queued);
1633 if (unlikely(r && r != -ENOENT)) {
1634 DMERR_LIMIT("%s: policy_lookup() failed with r = %d",
1635 cache_device_name(cache), r);
1636 bio_io_error(bio);
1637 return DM_MAPIO_SUBMITTED;
1638 }
1639
1640 if (background_queued)
1641 wake_migration_worker(cache);
1642 }
1643
1644 if (r == -ENOENT) {
1645 struct per_bio_data *pb = get_per_bio_data(bio);
1646
1647 /*
1648 * Miss.
1649 */
1650 inc_miss_counter(cache, bio);
1651 if (pb->req_nr == 0) {
1652 accounted_begin(cache, bio);
1653 remap_to_origin_clear_discard(cache, bio, block);
1654 } else {
1655 /*
1656 * This is a duplicate writethrough io that is no
1657 * longer needed because the block has been demoted.
1658 */
1659 bio_endio(bio);
1660 return DM_MAPIO_SUBMITTED;
1661 }
1662 } else {
1663 /*
1664 * Hit.
1665 */
1666 inc_hit_counter(cache, bio);
1667
1668 /*
1669 * Passthrough always maps to the origin, invalidating any
1670 * cache blocks that are written to.
1671 */
1672 if (passthrough_mode(cache)) {
1673 if (bio_data_dir(bio) == WRITE) {
1674 bio_drop_shared_lock(cache, bio);
1675 atomic_inc(&cache->stats.demotion);
1676 invalidate_start(cache, cblock, block, bio);
1677 } else
1678 remap_to_origin_clear_discard(cache, bio, block);
1679 } else {
1680 if (bio_data_dir(bio) == WRITE && writethrough_mode(cache) &&
1681 !is_dirty(cache, cblock)) {
1682 remap_to_origin_and_cache(cache, bio, block, cblock);
1683 accounted_begin(cache, bio);
1684 } else
1685 remap_to_cache_dirty(cache, bio, block, cblock);
1686 }
1687 }
1688
1689 /*
1690 * dm core turns FUA requests into a separate payload and FLUSH req.
1691 */
1692 if (bio->bi_opf & REQ_FUA) {
1693 /*
1694 * issue_after_commit will call accounted_begin a second time. So
1695 * we call accounted_complete() to avoid double accounting.
1696 */
1697 accounted_complete(cache, bio);
1698 issue_after_commit(&cache->committer, bio);
1699 *commit_needed = true;
1700 return DM_MAPIO_SUBMITTED;
1701 }
1702
1703 return DM_MAPIO_REMAPPED;
1704}
1705
1706static bool process_bio(struct cache *cache, struct bio *bio)
1707{
1708 bool commit_needed;
1709
1710 if (map_bio(cache, bio, get_bio_block(cache, bio), &commit_needed) == DM_MAPIO_REMAPPED)
1711 dm_submit_bio_remap(bio, NULL);
1712
1713 return commit_needed;
1714}
1715
1716/*
1717 * A non-zero return indicates read_only or fail_io mode.
1718 */
1719static int commit(struct cache *cache, bool clean_shutdown)
1720{
1721 int r;
1722
1723 if (get_cache_mode(cache) >= CM_READ_ONLY)
1724 return -EINVAL;
1725
1726 atomic_inc(&cache->stats.commit_count);
1727 r = dm_cache_commit(cache->cmd, clean_shutdown);
1728 if (r)
1729 metadata_operation_failed(cache, "dm_cache_commit", r);
1730
1731 return r;
1732}
1733
1734/*
1735 * Used by the batcher.
1736 */
1737static blk_status_t commit_op(void *context)
1738{
1739 struct cache *cache = context;
1740
1741 if (dm_cache_changed_this_transaction(cache->cmd))
1742 return errno_to_blk_status(commit(cache, false));
1743
1744 return 0;
1745}
1746
1747/*----------------------------------------------------------------*/
1748
1749static bool process_flush_bio(struct cache *cache, struct bio *bio)
1750{
1751 struct per_bio_data *pb = get_per_bio_data(bio);
1752
1753 if (!pb->req_nr)
1754 remap_to_origin(cache, bio);
1755 else
1756 remap_to_cache(cache, bio, 0);
1757
1758 issue_after_commit(&cache->committer, bio);
1759 return true;
1760}
1761
1762static bool process_discard_bio(struct cache *cache, struct bio *bio)
1763{
1764 dm_dblock_t b, e;
1765
1766 // FIXME: do we need to lock the region? Or can we just assume the
1767 // user wont be so foolish as to issue discard concurrently with
1768 // other IO?
1769 calc_discard_block_range(cache, bio, &b, &e);
1770 while (b != e) {
1771 set_discard(cache, b);
1772 b = to_dblock(from_dblock(b) + 1);
1773 }
1774
1775 if (cache->features.discard_passdown) {
1776 remap_to_origin(cache, bio);
1777 dm_submit_bio_remap(bio, NULL);
1778 } else
1779 bio_endio(bio);
1780
1781 return false;
1782}
1783
1784static void process_deferred_bios(struct work_struct *ws)
1785{
1786 struct cache *cache = container_of(ws, struct cache, deferred_bio_worker);
1787
1788 bool commit_needed = false;
1789 struct bio_list bios;
1790 struct bio *bio;
1791
1792 bio_list_init(&bios);
1793
1794 spin_lock_irq(&cache->lock);
1795 bio_list_merge(&bios, &cache->deferred_bios);
1796 bio_list_init(&cache->deferred_bios);
1797 spin_unlock_irq(&cache->lock);
1798
1799 while ((bio = bio_list_pop(&bios))) {
1800 if (bio->bi_opf & REQ_PREFLUSH)
1801 commit_needed = process_flush_bio(cache, bio) || commit_needed;
1802
1803 else if (bio_op(bio) == REQ_OP_DISCARD)
1804 commit_needed = process_discard_bio(cache, bio) || commit_needed;
1805
1806 else
1807 commit_needed = process_bio(cache, bio) || commit_needed;
1808 }
1809
1810 if (commit_needed)
1811 schedule_commit(&cache->committer);
1812}
1813
1814/*----------------------------------------------------------------
1815 * Main worker loop
1816 *--------------------------------------------------------------*/
1817
1818static void requeue_deferred_bios(struct cache *cache)
1819{
1820 struct bio *bio;
1821 struct bio_list bios;
1822
1823 bio_list_init(&bios);
1824 bio_list_merge(&bios, &cache->deferred_bios);
1825 bio_list_init(&cache->deferred_bios);
1826
1827 while ((bio = bio_list_pop(&bios))) {
1828 bio->bi_status = BLK_STS_DM_REQUEUE;
1829 bio_endio(bio);
1830 }
1831}
1832
1833/*
1834 * We want to commit periodically so that not too much
1835 * unwritten metadata builds up.
1836 */
1837static void do_waker(struct work_struct *ws)
1838{
1839 struct cache *cache = container_of(to_delayed_work(ws), struct cache, waker);
1840
1841 policy_tick(cache->policy, true);
1842 wake_migration_worker(cache);
1843 schedule_commit(&cache->committer);
1844 queue_delayed_work(cache->wq, &cache->waker, COMMIT_PERIOD);
1845}
1846
1847static void check_migrations(struct work_struct *ws)
1848{
1849 int r;
1850 struct policy_work *op;
1851 struct cache *cache = container_of(ws, struct cache, migration_worker);
1852 enum busy b;
1853
1854 for (;;) {
1855 b = spare_migration_bandwidth(cache);
1856
1857 r = policy_get_background_work(cache->policy, b == IDLE, &op);
1858 if (r == -ENODATA)
1859 break;
1860
1861 if (r) {
1862 DMERR_LIMIT("%s: policy_background_work failed",
1863 cache_device_name(cache));
1864 break;
1865 }
1866
1867 r = mg_start(cache, op, NULL);
1868 if (r)
1869 break;
1870 }
1871}
1872
1873/*----------------------------------------------------------------
1874 * Target methods
1875 *--------------------------------------------------------------*/
1876
1877/*
1878 * This function gets called on the error paths of the constructor, so we
1879 * have to cope with a partially initialised struct.
1880 */
1881static void destroy(struct cache *cache)
1882{
1883 unsigned i;
1884
1885 mempool_exit(&cache->migration_pool);
1886
1887 if (cache->prison)
1888 dm_bio_prison_destroy_v2(cache->prison);
1889
1890 cancel_delayed_work_sync(&cache->waker);
1891 if (cache->wq)
1892 destroy_workqueue(cache->wq);
1893
1894 if (cache->dirty_bitset)
1895 free_bitset(cache->dirty_bitset);
1896
1897 if (cache->discard_bitset)
1898 free_bitset(cache->discard_bitset);
1899
1900 if (cache->copier)
1901 dm_kcopyd_client_destroy(cache->copier);
1902
1903 if (cache->cmd)
1904 dm_cache_metadata_close(cache->cmd);
1905
1906 if (cache->metadata_dev)
1907 dm_put_device(cache->ti, cache->metadata_dev);
1908
1909 if (cache->origin_dev)
1910 dm_put_device(cache->ti, cache->origin_dev);
1911
1912 if (cache->cache_dev)
1913 dm_put_device(cache->ti, cache->cache_dev);
1914
1915 if (cache->policy)
1916 dm_cache_policy_destroy(cache->policy);
1917
1918 for (i = 0; i < cache->nr_ctr_args ; i++)
1919 kfree(cache->ctr_args[i]);
1920 kfree(cache->ctr_args);
1921
1922 bioset_exit(&cache->bs);
1923
1924 kfree(cache);
1925}
1926
1927static void cache_dtr(struct dm_target *ti)
1928{
1929 struct cache *cache = ti->private;
1930
1931 destroy(cache);
1932}
1933
1934static sector_t get_dev_size(struct dm_dev *dev)
1935{
1936 return bdev_nr_sectors(dev->bdev);
1937}
1938
1939/*----------------------------------------------------------------*/
1940
1941/*
1942 * Construct a cache device mapping.
1943 *
1944 * cache <metadata dev> <cache dev> <origin dev> <block size>
1945 * <#feature args> [<feature arg>]*
1946 * <policy> <#policy args> [<policy arg>]*
1947 *
1948 * metadata dev : fast device holding the persistent metadata
1949 * cache dev : fast device holding cached data blocks
1950 * origin dev : slow device holding original data blocks
1951 * block size : cache unit size in sectors
1952 *
1953 * #feature args : number of feature arguments passed
1954 * feature args : writethrough. (The default is writeback.)
1955 *
1956 * policy : the replacement policy to use
1957 * #policy args : an even number of policy arguments corresponding
1958 * to key/value pairs passed to the policy
1959 * policy args : key/value pairs passed to the policy
1960 * E.g. 'sequential_threshold 1024'
1961 * See cache-policies.txt for details.
1962 *
1963 * Optional feature arguments are:
1964 * writethrough : write through caching that prohibits cache block
1965 * content from being different from origin block content.
1966 * Without this argument, the default behaviour is to write
1967 * back cache block contents later for performance reasons,
1968 * so they may differ from the corresponding origin blocks.
1969 */
1970struct cache_args {
1971 struct dm_target *ti;
1972
1973 struct dm_dev *metadata_dev;
1974
1975 struct dm_dev *cache_dev;
1976 sector_t cache_sectors;
1977
1978 struct dm_dev *origin_dev;
1979 sector_t origin_sectors;
1980
1981 uint32_t block_size;
1982
1983 const char *policy_name;
1984 int policy_argc;
1985 const char **policy_argv;
1986
1987 struct cache_features features;
1988};
1989
1990static void destroy_cache_args(struct cache_args *ca)
1991{
1992 if (ca->metadata_dev)
1993 dm_put_device(ca->ti, ca->metadata_dev);
1994
1995 if (ca->cache_dev)
1996 dm_put_device(ca->ti, ca->cache_dev);
1997
1998 if (ca->origin_dev)
1999 dm_put_device(ca->ti, ca->origin_dev);
2000
2001 kfree(ca);
2002}
2003
2004static bool at_least_one_arg(struct dm_arg_set *as, char **error)
2005{
2006 if (!as->argc) {
2007 *error = "Insufficient args";
2008 return false;
2009 }
2010
2011 return true;
2012}
2013
2014static int parse_metadata_dev(struct cache_args *ca, struct dm_arg_set *as,
2015 char **error)
2016{
2017 int r;
2018 sector_t metadata_dev_size;
2019
2020 if (!at_least_one_arg(as, error))
2021 return -EINVAL;
2022
2023 r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
2024 &ca->metadata_dev);
2025 if (r) {
2026 *error = "Error opening metadata device";
2027 return r;
2028 }
2029
2030 metadata_dev_size = get_dev_size(ca->metadata_dev);
2031 if (metadata_dev_size > DM_CACHE_METADATA_MAX_SECTORS_WARNING)
2032 DMWARN("Metadata device %pg is larger than %u sectors: excess space will not be used.",
2033 ca->metadata_dev->bdev, THIN_METADATA_MAX_SECTORS);
2034
2035 return 0;
2036}
2037
2038static int parse_cache_dev(struct cache_args *ca, struct dm_arg_set *as,
2039 char **error)
2040{
2041 int r;
2042
2043 if (!at_least_one_arg(as, error))
2044 return -EINVAL;
2045
2046 r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
2047 &ca->cache_dev);
2048 if (r) {
2049 *error = "Error opening cache device";
2050 return r;
2051 }
2052 ca->cache_sectors = get_dev_size(ca->cache_dev);
2053
2054 return 0;
2055}
2056
2057static int parse_origin_dev(struct cache_args *ca, struct dm_arg_set *as,
2058 char **error)
2059{
2060 int r;
2061
2062 if (!at_least_one_arg(as, error))
2063 return -EINVAL;
2064
2065 r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
2066 &ca->origin_dev);
2067 if (r) {
2068 *error = "Error opening origin device";
2069 return r;
2070 }
2071
2072 ca->origin_sectors = get_dev_size(ca->origin_dev);
2073 if (ca->ti->len > ca->origin_sectors) {
2074 *error = "Device size larger than cached device";
2075 return -EINVAL;
2076 }
2077
2078 return 0;
2079}
2080
2081static int parse_block_size(struct cache_args *ca, struct dm_arg_set *as,
2082 char **error)
2083{
2084 unsigned long block_size;
2085
2086 if (!at_least_one_arg(as, error))
2087 return -EINVAL;
2088
2089 if (kstrtoul(dm_shift_arg(as), 10, &block_size) || !block_size ||
2090 block_size < DATA_DEV_BLOCK_SIZE_MIN_SECTORS ||
2091 block_size > DATA_DEV_BLOCK_SIZE_MAX_SECTORS ||
2092 block_size & (DATA_DEV_BLOCK_SIZE_MIN_SECTORS - 1)) {
2093 *error = "Invalid data block size";
2094 return -EINVAL;
2095 }
2096
2097 if (block_size > ca->cache_sectors) {
2098 *error = "Data block size is larger than the cache device";
2099 return -EINVAL;
2100 }
2101
2102 ca->block_size = block_size;
2103
2104 return 0;
2105}
2106
2107static void init_features(struct cache_features *cf)
2108{
2109 cf->mode = CM_WRITE;
2110 cf->io_mode = CM_IO_WRITEBACK;
2111 cf->metadata_version = 1;
2112 cf->discard_passdown = true;
2113}
2114
2115static int parse_features(struct cache_args *ca, struct dm_arg_set *as,
2116 char **error)
2117{
2118 static const struct dm_arg _args[] = {
2119 {0, 3, "Invalid number of cache feature arguments"},
2120 };
2121
2122 int r, mode_ctr = 0;
2123 unsigned argc;
2124 const char *arg;
2125 struct cache_features *cf = &ca->features;
2126
2127 init_features(cf);
2128
2129 r = dm_read_arg_group(_args, as, &argc, error);
2130 if (r)
2131 return -EINVAL;
2132
2133 while (argc--) {
2134 arg = dm_shift_arg(as);
2135
2136 if (!strcasecmp(arg, "writeback")) {
2137 cf->io_mode = CM_IO_WRITEBACK;
2138 mode_ctr++;
2139 }
2140
2141 else if (!strcasecmp(arg, "writethrough")) {
2142 cf->io_mode = CM_IO_WRITETHROUGH;
2143 mode_ctr++;
2144 }
2145
2146 else if (!strcasecmp(arg, "passthrough")) {
2147 cf->io_mode = CM_IO_PASSTHROUGH;
2148 mode_ctr++;
2149 }
2150
2151 else if (!strcasecmp(arg, "metadata2"))
2152 cf->metadata_version = 2;
2153
2154 else if (!strcasecmp(arg, "no_discard_passdown"))
2155 cf->discard_passdown = false;
2156
2157 else {
2158 *error = "Unrecognised cache feature requested";
2159 return -EINVAL;
2160 }
2161 }
2162
2163 if (mode_ctr > 1) {
2164 *error = "Duplicate cache io_mode features requested";
2165 return -EINVAL;
2166 }
2167
2168 return 0;
2169}
2170
2171static int parse_policy(struct cache_args *ca, struct dm_arg_set *as,
2172 char **error)
2173{
2174 static const struct dm_arg _args[] = {
2175 {0, 1024, "Invalid number of policy arguments"},
2176 };
2177
2178 int r;
2179
2180 if (!at_least_one_arg(as, error))
2181 return -EINVAL;
2182
2183 ca->policy_name = dm_shift_arg(as);
2184
2185 r = dm_read_arg_group(_args, as, &ca->policy_argc, error);
2186 if (r)
2187 return -EINVAL;
2188
2189 ca->policy_argv = (const char **)as->argv;
2190 dm_consume_args(as, ca->policy_argc);
2191
2192 return 0;
2193}
2194
2195static int parse_cache_args(struct cache_args *ca, int argc, char **argv,
2196 char **error)
2197{
2198 int r;
2199 struct dm_arg_set as;
2200
2201 as.argc = argc;
2202 as.argv = argv;
2203
2204 r = parse_metadata_dev(ca, &as, error);
2205 if (r)
2206 return r;
2207
2208 r = parse_cache_dev(ca, &as, error);
2209 if (r)
2210 return r;
2211
2212 r = parse_origin_dev(ca, &as, error);
2213 if (r)
2214 return r;
2215
2216 r = parse_block_size(ca, &as, error);
2217 if (r)
2218 return r;
2219
2220 r = parse_features(ca, &as, error);
2221 if (r)
2222 return r;
2223
2224 r = parse_policy(ca, &as, error);
2225 if (r)
2226 return r;
2227
2228 return 0;
2229}
2230
2231/*----------------------------------------------------------------*/
2232
2233static struct kmem_cache *migration_cache;
2234
2235#define NOT_CORE_OPTION 1
2236
2237static int process_config_option(struct cache *cache, const char *key, const char *value)
2238{
2239 unsigned long tmp;
2240
2241 if (!strcasecmp(key, "migration_threshold")) {
2242 if (kstrtoul(value, 10, &tmp))
2243 return -EINVAL;
2244
2245 cache->migration_threshold = tmp;
2246 return 0;
2247 }
2248
2249 return NOT_CORE_OPTION;
2250}
2251
2252static int set_config_value(struct cache *cache, const char *key, const char *value)
2253{
2254 int r = process_config_option(cache, key, value);
2255
2256 if (r == NOT_CORE_OPTION)
2257 r = policy_set_config_value(cache->policy, key, value);
2258
2259 if (r)
2260 DMWARN("bad config value for %s: %s", key, value);
2261
2262 return r;
2263}
2264
2265static int set_config_values(struct cache *cache, int argc, const char **argv)
2266{
2267 int r = 0;
2268
2269 if (argc & 1) {
2270 DMWARN("Odd number of policy arguments given but they should be <key> <value> pairs.");
2271 return -EINVAL;
2272 }
2273
2274 while (argc) {
2275 r = set_config_value(cache, argv[0], argv[1]);
2276 if (r)
2277 break;
2278
2279 argc -= 2;
2280 argv += 2;
2281 }
2282
2283 return r;
2284}
2285
2286static int create_cache_policy(struct cache *cache, struct cache_args *ca,
2287 char **error)
2288{
2289 struct dm_cache_policy *p = dm_cache_policy_create(ca->policy_name,
2290 cache->cache_size,
2291 cache->origin_sectors,
2292 cache->sectors_per_block);
2293 if (IS_ERR(p)) {
2294 *error = "Error creating cache's policy";
2295 return PTR_ERR(p);
2296 }
2297 cache->policy = p;
2298 BUG_ON(!cache->policy);
2299
2300 return 0;
2301}
2302
2303/*
2304 * We want the discard block size to be at least the size of the cache
2305 * block size and have no more than 2^14 discard blocks across the origin.
2306 */
2307#define MAX_DISCARD_BLOCKS (1 << 14)
2308
2309static bool too_many_discard_blocks(sector_t discard_block_size,
2310 sector_t origin_size)
2311{
2312 (void) sector_div(origin_size, discard_block_size);
2313
2314 return origin_size > MAX_DISCARD_BLOCKS;
2315}
2316
2317static sector_t calculate_discard_block_size(sector_t cache_block_size,
2318 sector_t origin_size)
2319{
2320 sector_t discard_block_size = cache_block_size;
2321
2322 if (origin_size)
2323 while (too_many_discard_blocks(discard_block_size, origin_size))
2324 discard_block_size *= 2;
2325
2326 return discard_block_size;
2327}
2328
2329static void set_cache_size(struct cache *cache, dm_cblock_t size)
2330{
2331 dm_block_t nr_blocks = from_cblock(size);
2332
2333 if (nr_blocks > (1 << 20) && cache->cache_size != size)
2334 DMWARN_LIMIT("You have created a cache device with a lot of individual cache blocks (%llu)\n"
2335 "All these mappings can consume a lot of kernel memory, and take some time to read/write.\n"
2336 "Please consider increasing the cache block size to reduce the overall cache block count.",
2337 (unsigned long long) nr_blocks);
2338
2339 cache->cache_size = size;
2340}
2341
2342#define DEFAULT_MIGRATION_THRESHOLD 2048
2343
2344static int cache_create(struct cache_args *ca, struct cache **result)
2345{
2346 int r = 0;
2347 char **error = &ca->ti->error;
2348 struct cache *cache;
2349 struct dm_target *ti = ca->ti;
2350 dm_block_t origin_blocks;
2351 struct dm_cache_metadata *cmd;
2352 bool may_format = ca->features.mode == CM_WRITE;
2353
2354 cache = kzalloc(sizeof(*cache), GFP_KERNEL);
2355 if (!cache)
2356 return -ENOMEM;
2357
2358 cache->ti = ca->ti;
2359 ti->private = cache;
2360 ti->accounts_remapped_io = true;
2361 ti->num_flush_bios = 2;
2362 ti->flush_supported = true;
2363
2364 ti->num_discard_bios = 1;
2365 ti->discards_supported = true;
2366
2367 ti->per_io_data_size = sizeof(struct per_bio_data);
2368
2369 cache->features = ca->features;
2370 if (writethrough_mode(cache)) {
2371 /* Create bioset for writethrough bios issued to origin */
2372 r = bioset_init(&cache->bs, BIO_POOL_SIZE, 0, 0);
2373 if (r)
2374 goto bad;
2375 }
2376
2377 cache->metadata_dev = ca->metadata_dev;
2378 cache->origin_dev = ca->origin_dev;
2379 cache->cache_dev = ca->cache_dev;
2380
2381 ca->metadata_dev = ca->origin_dev = ca->cache_dev = NULL;
2382
2383 origin_blocks = cache->origin_sectors = ca->origin_sectors;
2384 origin_blocks = block_div(origin_blocks, ca->block_size);
2385 cache->origin_blocks = to_oblock(origin_blocks);
2386
2387 cache->sectors_per_block = ca->block_size;
2388 if (dm_set_target_max_io_len(ti, cache->sectors_per_block)) {
2389 r = -EINVAL;
2390 goto bad;
2391 }
2392
2393 if (ca->block_size & (ca->block_size - 1)) {
2394 dm_block_t cache_size = ca->cache_sectors;
2395
2396 cache->sectors_per_block_shift = -1;
2397 cache_size = block_div(cache_size, ca->block_size);
2398 set_cache_size(cache, to_cblock(cache_size));
2399 } else {
2400 cache->sectors_per_block_shift = __ffs(ca->block_size);
2401 set_cache_size(cache, to_cblock(ca->cache_sectors >> cache->sectors_per_block_shift));
2402 }
2403
2404 r = create_cache_policy(cache, ca, error);
2405 if (r)
2406 goto bad;
2407
2408 cache->policy_nr_args = ca->policy_argc;
2409 cache->migration_threshold = DEFAULT_MIGRATION_THRESHOLD;
2410
2411 r = set_config_values(cache, ca->policy_argc, ca->policy_argv);
2412 if (r) {
2413 *error = "Error setting cache policy's config values";
2414 goto bad;
2415 }
2416
2417 cmd = dm_cache_metadata_open(cache->metadata_dev->bdev,
2418 ca->block_size, may_format,
2419 dm_cache_policy_get_hint_size(cache->policy),
2420 ca->features.metadata_version);
2421 if (IS_ERR(cmd)) {
2422 *error = "Error creating metadata object";
2423 r = PTR_ERR(cmd);
2424 goto bad;
2425 }
2426 cache->cmd = cmd;
2427 set_cache_mode(cache, CM_WRITE);
2428 if (get_cache_mode(cache) != CM_WRITE) {
2429 *error = "Unable to get write access to metadata, please check/repair metadata.";
2430 r = -EINVAL;
2431 goto bad;
2432 }
2433
2434 if (passthrough_mode(cache)) {
2435 bool all_clean;
2436
2437 r = dm_cache_metadata_all_clean(cache->cmd, &all_clean);
2438 if (r) {
2439 *error = "dm_cache_metadata_all_clean() failed";
2440 goto bad;
2441 }
2442
2443 if (!all_clean) {
2444 *error = "Cannot enter passthrough mode unless all blocks are clean";
2445 r = -EINVAL;
2446 goto bad;
2447 }
2448
2449 policy_allow_migrations(cache->policy, false);
2450 }
2451
2452 spin_lock_init(&cache->lock);
2453 bio_list_init(&cache->deferred_bios);
2454 atomic_set(&cache->nr_allocated_migrations, 0);
2455 atomic_set(&cache->nr_io_migrations, 0);
2456 init_waitqueue_head(&cache->migration_wait);
2457
2458 r = -ENOMEM;
2459 atomic_set(&cache->nr_dirty, 0);
2460 cache->dirty_bitset = alloc_bitset(from_cblock(cache->cache_size));
2461 if (!cache->dirty_bitset) {
2462 *error = "could not allocate dirty bitset";
2463 goto bad;
2464 }
2465 clear_bitset(cache->dirty_bitset, from_cblock(cache->cache_size));
2466
2467 cache->discard_block_size =
2468 calculate_discard_block_size(cache->sectors_per_block,
2469 cache->origin_sectors);
2470 cache->discard_nr_blocks = to_dblock(dm_sector_div_up(cache->origin_sectors,
2471 cache->discard_block_size));
2472 cache->discard_bitset = alloc_bitset(from_dblock(cache->discard_nr_blocks));
2473 if (!cache->discard_bitset) {
2474 *error = "could not allocate discard bitset";
2475 goto bad;
2476 }
2477 clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks));
2478
2479 cache->copier = dm_kcopyd_client_create(&dm_kcopyd_throttle);
2480 if (IS_ERR(cache->copier)) {
2481 *error = "could not create kcopyd client";
2482 r = PTR_ERR(cache->copier);
2483 goto bad;
2484 }
2485
2486 cache->wq = alloc_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM, 0);
2487 if (!cache->wq) {
2488 *error = "could not create workqueue for metadata object";
2489 goto bad;
2490 }
2491 INIT_WORK(&cache->deferred_bio_worker, process_deferred_bios);
2492 INIT_WORK(&cache->migration_worker, check_migrations);
2493 INIT_DELAYED_WORK(&cache->waker, do_waker);
2494
2495 cache->prison = dm_bio_prison_create_v2(cache->wq);
2496 if (!cache->prison) {
2497 *error = "could not create bio prison";
2498 goto bad;
2499 }
2500
2501 r = mempool_init_slab_pool(&cache->migration_pool, MIGRATION_POOL_SIZE,
2502 migration_cache);
2503 if (r) {
2504 *error = "Error creating cache's migration mempool";
2505 goto bad;
2506 }
2507
2508 cache->need_tick_bio = true;
2509 cache->sized = false;
2510 cache->invalidate = false;
2511 cache->commit_requested = false;
2512 cache->loaded_mappings = false;
2513 cache->loaded_discards = false;
2514
2515 load_stats(cache);
2516
2517 atomic_set(&cache->stats.demotion, 0);
2518 atomic_set(&cache->stats.promotion, 0);
2519 atomic_set(&cache->stats.copies_avoided, 0);
2520 atomic_set(&cache->stats.cache_cell_clash, 0);
2521 atomic_set(&cache->stats.commit_count, 0);
2522 atomic_set(&cache->stats.discard_count, 0);
2523
2524 spin_lock_init(&cache->invalidation_lock);
2525 INIT_LIST_HEAD(&cache->invalidation_requests);
2526
2527 batcher_init(&cache->committer, commit_op, cache,
2528 issue_op, cache, cache->wq);
2529 dm_iot_init(&cache->tracker);
2530
2531 init_rwsem(&cache->background_work_lock);
2532 prevent_background_work(cache);
2533
2534 *result = cache;
2535 return 0;
2536bad:
2537 destroy(cache);
2538 return r;
2539}
2540
2541static int copy_ctr_args(struct cache *cache, int argc, const char **argv)
2542{
2543 unsigned i;
2544 const char **copy;
2545
2546 copy = kcalloc(argc, sizeof(*copy), GFP_KERNEL);
2547 if (!copy)
2548 return -ENOMEM;
2549 for (i = 0; i < argc; i++) {
2550 copy[i] = kstrdup(argv[i], GFP_KERNEL);
2551 if (!copy[i]) {
2552 while (i--)
2553 kfree(copy[i]);
2554 kfree(copy);
2555 return -ENOMEM;
2556 }
2557 }
2558
2559 cache->nr_ctr_args = argc;
2560 cache->ctr_args = copy;
2561
2562 return 0;
2563}
2564
2565static int cache_ctr(struct dm_target *ti, unsigned argc, char **argv)
2566{
2567 int r = -EINVAL;
2568 struct cache_args *ca;
2569 struct cache *cache = NULL;
2570
2571 ca = kzalloc(sizeof(*ca), GFP_KERNEL);
2572 if (!ca) {
2573 ti->error = "Error allocating memory for cache";
2574 return -ENOMEM;
2575 }
2576 ca->ti = ti;
2577
2578 r = parse_cache_args(ca, argc, argv, &ti->error);
2579 if (r)
2580 goto out;
2581
2582 r = cache_create(ca, &cache);
2583 if (r)
2584 goto out;
2585
2586 r = copy_ctr_args(cache, argc - 3, (const char **)argv + 3);
2587 if (r) {
2588 destroy(cache);
2589 goto out;
2590 }
2591
2592 ti->private = cache;
2593out:
2594 destroy_cache_args(ca);
2595 return r;
2596}
2597
2598/*----------------------------------------------------------------*/
2599
2600static int cache_map(struct dm_target *ti, struct bio *bio)
2601{
2602 struct cache *cache = ti->private;
2603
2604 int r;
2605 bool commit_needed;
2606 dm_oblock_t block = get_bio_block(cache, bio);
2607
2608 init_per_bio_data(bio);
2609 if (unlikely(from_oblock(block) >= from_oblock(cache->origin_blocks))) {
2610 /*
2611 * This can only occur if the io goes to a partial block at
2612 * the end of the origin device. We don't cache these.
2613 * Just remap to the origin and carry on.
2614 */
2615 remap_to_origin(cache, bio);
2616 accounted_begin(cache, bio);
2617 return DM_MAPIO_REMAPPED;
2618 }
2619
2620 if (discard_or_flush(bio)) {
2621 defer_bio(cache, bio);
2622 return DM_MAPIO_SUBMITTED;
2623 }
2624
2625 r = map_bio(cache, bio, block, &commit_needed);
2626 if (commit_needed)
2627 schedule_commit(&cache->committer);
2628
2629 return r;
2630}
2631
2632static int cache_end_io(struct dm_target *ti, struct bio *bio, blk_status_t *error)
2633{
2634 struct cache *cache = ti->private;
2635 unsigned long flags;
2636 struct per_bio_data *pb = get_per_bio_data(bio);
2637
2638 if (pb->tick) {
2639 policy_tick(cache->policy, false);
2640
2641 spin_lock_irqsave(&cache->lock, flags);
2642 cache->need_tick_bio = true;
2643 spin_unlock_irqrestore(&cache->lock, flags);
2644 }
2645
2646 bio_drop_shared_lock(cache, bio);
2647 accounted_complete(cache, bio);
2648
2649 return DM_ENDIO_DONE;
2650}
2651
2652static int write_dirty_bitset(struct cache *cache)
2653{
2654 int r;
2655
2656 if (get_cache_mode(cache) >= CM_READ_ONLY)
2657 return -EINVAL;
2658
2659 r = dm_cache_set_dirty_bits(cache->cmd, from_cblock(cache->cache_size), cache->dirty_bitset);
2660 if (r)
2661 metadata_operation_failed(cache, "dm_cache_set_dirty_bits", r);
2662
2663 return r;
2664}
2665
2666static int write_discard_bitset(struct cache *cache)
2667{
2668 unsigned i, r;
2669
2670 if (get_cache_mode(cache) >= CM_READ_ONLY)
2671 return -EINVAL;
2672
2673 r = dm_cache_discard_bitset_resize(cache->cmd, cache->discard_block_size,
2674 cache->discard_nr_blocks);
2675 if (r) {
2676 DMERR("%s: could not resize on-disk discard bitset", cache_device_name(cache));
2677 metadata_operation_failed(cache, "dm_cache_discard_bitset_resize", r);
2678 return r;
2679 }
2680
2681 for (i = 0; i < from_dblock(cache->discard_nr_blocks); i++) {
2682 r = dm_cache_set_discard(cache->cmd, to_dblock(i),
2683 is_discarded(cache, to_dblock(i)));
2684 if (r) {
2685 metadata_operation_failed(cache, "dm_cache_set_discard", r);
2686 return r;
2687 }
2688 }
2689
2690 return 0;
2691}
2692
2693static int write_hints(struct cache *cache)
2694{
2695 int r;
2696
2697 if (get_cache_mode(cache) >= CM_READ_ONLY)
2698 return -EINVAL;
2699
2700 r = dm_cache_write_hints(cache->cmd, cache->policy);
2701 if (r) {
2702 metadata_operation_failed(cache, "dm_cache_write_hints", r);
2703 return r;
2704 }
2705
2706 return 0;
2707}
2708
2709/*
2710 * returns true on success
2711 */
2712static bool sync_metadata(struct cache *cache)
2713{
2714 int r1, r2, r3, r4;
2715
2716 r1 = write_dirty_bitset(cache);
2717 if (r1)
2718 DMERR("%s: could not write dirty bitset", cache_device_name(cache));
2719
2720 r2 = write_discard_bitset(cache);
2721 if (r2)
2722 DMERR("%s: could not write discard bitset", cache_device_name(cache));
2723
2724 save_stats(cache);
2725
2726 r3 = write_hints(cache);
2727 if (r3)
2728 DMERR("%s: could not write hints", cache_device_name(cache));
2729
2730 /*
2731 * If writing the above metadata failed, we still commit, but don't
2732 * set the clean shutdown flag. This will effectively force every
2733 * dirty bit to be set on reload.
2734 */
2735 r4 = commit(cache, !r1 && !r2 && !r3);
2736 if (r4)
2737 DMERR("%s: could not write cache metadata", cache_device_name(cache));
2738
2739 return !r1 && !r2 && !r3 && !r4;
2740}
2741
2742static void cache_postsuspend(struct dm_target *ti)
2743{
2744 struct cache *cache = ti->private;
2745
2746 prevent_background_work(cache);
2747 BUG_ON(atomic_read(&cache->nr_io_migrations));
2748
2749 cancel_delayed_work_sync(&cache->waker);
2750 drain_workqueue(cache->wq);
2751 WARN_ON(cache->tracker.in_flight);
2752
2753 /*
2754 * If it's a flush suspend there won't be any deferred bios, so this
2755 * call is harmless.
2756 */
2757 requeue_deferred_bios(cache);
2758
2759 if (get_cache_mode(cache) == CM_WRITE)
2760 (void) sync_metadata(cache);
2761}
2762
2763static int load_mapping(void *context, dm_oblock_t oblock, dm_cblock_t cblock,
2764 bool dirty, uint32_t hint, bool hint_valid)
2765{
2766 struct cache *cache = context;
2767
2768 if (dirty) {
2769 set_bit(from_cblock(cblock), cache->dirty_bitset);
2770 atomic_inc(&cache->nr_dirty);
2771 } else
2772 clear_bit(from_cblock(cblock), cache->dirty_bitset);
2773
2774 return policy_load_mapping(cache->policy, oblock, cblock, dirty, hint, hint_valid);
2775}
2776
2777/*
2778 * The discard block size in the on disk metadata is not
2779 * necessarily the same as we're currently using. So we have to
2780 * be careful to only set the discarded attribute if we know it
2781 * covers a complete block of the new size.
2782 */
2783struct discard_load_info {
2784 struct cache *cache;
2785
2786 /*
2787 * These blocks are sized using the on disk dblock size, rather
2788 * than the current one.
2789 */
2790 dm_block_t block_size;
2791 dm_block_t discard_begin, discard_end;
2792};
2793
2794static void discard_load_info_init(struct cache *cache,
2795 struct discard_load_info *li)
2796{
2797 li->cache = cache;
2798 li->discard_begin = li->discard_end = 0;
2799}
2800
2801static void set_discard_range(struct discard_load_info *li)
2802{
2803 sector_t b, e;
2804
2805 if (li->discard_begin == li->discard_end)
2806 return;
2807
2808 /*
2809 * Convert to sectors.
2810 */
2811 b = li->discard_begin * li->block_size;
2812 e = li->discard_end * li->block_size;
2813
2814 /*
2815 * Then convert back to the current dblock size.
2816 */
2817 b = dm_sector_div_up(b, li->cache->discard_block_size);
2818 sector_div(e, li->cache->discard_block_size);
2819
2820 /*
2821 * The origin may have shrunk, so we need to check we're still in
2822 * bounds.
2823 */
2824 if (e > from_dblock(li->cache->discard_nr_blocks))
2825 e = from_dblock(li->cache->discard_nr_blocks);
2826
2827 for (; b < e; b++)
2828 set_discard(li->cache, to_dblock(b));
2829}
2830
2831static int load_discard(void *context, sector_t discard_block_size,
2832 dm_dblock_t dblock, bool discard)
2833{
2834 struct discard_load_info *li = context;
2835
2836 li->block_size = discard_block_size;
2837
2838 if (discard) {
2839 if (from_dblock(dblock) == li->discard_end)
2840 /*
2841 * We're already in a discard range, just extend it.
2842 */
2843 li->discard_end = li->discard_end + 1ULL;
2844
2845 else {
2846 /*
2847 * Emit the old range and start a new one.
2848 */
2849 set_discard_range(li);
2850 li->discard_begin = from_dblock(dblock);
2851 li->discard_end = li->discard_begin + 1ULL;
2852 }
2853 } else {
2854 set_discard_range(li);
2855 li->discard_begin = li->discard_end = 0;
2856 }
2857
2858 return 0;
2859}
2860
2861static dm_cblock_t get_cache_dev_size(struct cache *cache)
2862{
2863 sector_t size = get_dev_size(cache->cache_dev);
2864 (void) sector_div(size, cache->sectors_per_block);
2865 return to_cblock(size);
2866}
2867
2868static bool can_resize(struct cache *cache, dm_cblock_t new_size)
2869{
2870 if (from_cblock(new_size) > from_cblock(cache->cache_size)) {
2871 if (cache->sized) {
2872 DMERR("%s: unable to extend cache due to missing cache table reload",
2873 cache_device_name(cache));
2874 return false;
2875 }
2876 }
2877
2878 /*
2879 * We can't drop a dirty block when shrinking the cache.
2880 */
2881 while (from_cblock(new_size) < from_cblock(cache->cache_size)) {
2882 new_size = to_cblock(from_cblock(new_size) + 1);
2883 if (is_dirty(cache, new_size)) {
2884 DMERR("%s: unable to shrink cache; cache block %llu is dirty",
2885 cache_device_name(cache),
2886 (unsigned long long) from_cblock(new_size));
2887 return false;
2888 }
2889 }
2890
2891 return true;
2892}
2893
2894static int resize_cache_dev(struct cache *cache, dm_cblock_t new_size)
2895{
2896 int r;
2897
2898 r = dm_cache_resize(cache->cmd, new_size);
2899 if (r) {
2900 DMERR("%s: could not resize cache metadata", cache_device_name(cache));
2901 metadata_operation_failed(cache, "dm_cache_resize", r);
2902 return r;
2903 }
2904
2905 set_cache_size(cache, new_size);
2906
2907 return 0;
2908}
2909
2910static int cache_preresume(struct dm_target *ti)
2911{
2912 int r = 0;
2913 struct cache *cache = ti->private;
2914 dm_cblock_t csize = get_cache_dev_size(cache);
2915
2916 /*
2917 * Check to see if the cache has resized.
2918 */
2919 if (!cache->sized) {
2920 r = resize_cache_dev(cache, csize);
2921 if (r)
2922 return r;
2923
2924 cache->sized = true;
2925
2926 } else if (csize != cache->cache_size) {
2927 if (!can_resize(cache, csize))
2928 return -EINVAL;
2929
2930 r = resize_cache_dev(cache, csize);
2931 if (r)
2932 return r;
2933 }
2934
2935 if (!cache->loaded_mappings) {
2936 r = dm_cache_load_mappings(cache->cmd, cache->policy,
2937 load_mapping, cache);
2938 if (r) {
2939 DMERR("%s: could not load cache mappings", cache_device_name(cache));
2940 metadata_operation_failed(cache, "dm_cache_load_mappings", r);
2941 return r;
2942 }
2943
2944 cache->loaded_mappings = true;
2945 }
2946
2947 if (!cache->loaded_discards) {
2948 struct discard_load_info li;
2949
2950 /*
2951 * The discard bitset could have been resized, or the
2952 * discard block size changed. To be safe we start by
2953 * setting every dblock to not discarded.
2954 */
2955 clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks));
2956
2957 discard_load_info_init(cache, &li);
2958 r = dm_cache_load_discards(cache->cmd, load_discard, &li);
2959 if (r) {
2960 DMERR("%s: could not load origin discards", cache_device_name(cache));
2961 metadata_operation_failed(cache, "dm_cache_load_discards", r);
2962 return r;
2963 }
2964 set_discard_range(&li);
2965
2966 cache->loaded_discards = true;
2967 }
2968
2969 return r;
2970}
2971
2972static void cache_resume(struct dm_target *ti)
2973{
2974 struct cache *cache = ti->private;
2975
2976 cache->need_tick_bio = true;
2977 allow_background_work(cache);
2978 do_waker(&cache->waker.work);
2979}
2980
2981static void emit_flags(struct cache *cache, char *result,
2982 unsigned maxlen, ssize_t *sz_ptr)
2983{
2984 ssize_t sz = *sz_ptr;
2985 struct cache_features *cf = &cache->features;
2986 unsigned count = (cf->metadata_version == 2) + !cf->discard_passdown + 1;
2987
2988 DMEMIT("%u ", count);
2989
2990 if (cf->metadata_version == 2)
2991 DMEMIT("metadata2 ");
2992
2993 if (writethrough_mode(cache))
2994 DMEMIT("writethrough ");
2995
2996 else if (passthrough_mode(cache))
2997 DMEMIT("passthrough ");
2998
2999 else if (writeback_mode(cache))
3000 DMEMIT("writeback ");
3001
3002 else {
3003 DMEMIT("unknown ");
3004 DMERR("%s: internal error: unknown io mode: %d",
3005 cache_device_name(cache), (int) cf->io_mode);
3006 }
3007
3008 if (!cf->discard_passdown)
3009 DMEMIT("no_discard_passdown ");
3010
3011 *sz_ptr = sz;
3012}
3013
3014/*
3015 * Status format:
3016 *
3017 * <metadata block size> <#used metadata blocks>/<#total metadata blocks>
3018 * <cache block size> <#used cache blocks>/<#total cache blocks>
3019 * <#read hits> <#read misses> <#write hits> <#write misses>
3020 * <#demotions> <#promotions> <#dirty>
3021 * <#features> <features>*
3022 * <#core args> <core args>
3023 * <policy name> <#policy args> <policy args>* <cache metadata mode> <needs_check>
3024 */
3025static void cache_status(struct dm_target *ti, status_type_t type,
3026 unsigned status_flags, char *result, unsigned maxlen)
3027{
3028 int r = 0;
3029 unsigned i;
3030 ssize_t sz = 0;
3031 dm_block_t nr_free_blocks_metadata = 0;
3032 dm_block_t nr_blocks_metadata = 0;
3033 char buf[BDEVNAME_SIZE];
3034 struct cache *cache = ti->private;
3035 dm_cblock_t residency;
3036 bool needs_check;
3037
3038 switch (type) {
3039 case STATUSTYPE_INFO:
3040 if (get_cache_mode(cache) == CM_FAIL) {
3041 DMEMIT("Fail");
3042 break;
3043 }
3044
3045 /* Commit to ensure statistics aren't out-of-date */
3046 if (!(status_flags & DM_STATUS_NOFLUSH_FLAG) && !dm_suspended(ti))
3047 (void) commit(cache, false);
3048
3049 r = dm_cache_get_free_metadata_block_count(cache->cmd, &nr_free_blocks_metadata);
3050 if (r) {
3051 DMERR("%s: dm_cache_get_free_metadata_block_count returned %d",
3052 cache_device_name(cache), r);
3053 goto err;
3054 }
3055
3056 r = dm_cache_get_metadata_dev_size(cache->cmd, &nr_blocks_metadata);
3057 if (r) {
3058 DMERR("%s: dm_cache_get_metadata_dev_size returned %d",
3059 cache_device_name(cache), r);
3060 goto err;
3061 }
3062
3063 residency = policy_residency(cache->policy);
3064
3065 DMEMIT("%u %llu/%llu %llu %llu/%llu %u %u %u %u %u %u %lu ",
3066 (unsigned)DM_CACHE_METADATA_BLOCK_SIZE,
3067 (unsigned long long)(nr_blocks_metadata - nr_free_blocks_metadata),
3068 (unsigned long long)nr_blocks_metadata,
3069 (unsigned long long)cache->sectors_per_block,
3070 (unsigned long long) from_cblock(residency),
3071 (unsigned long long) from_cblock(cache->cache_size),
3072 (unsigned) atomic_read(&cache->stats.read_hit),
3073 (unsigned) atomic_read(&cache->stats.read_miss),
3074 (unsigned) atomic_read(&cache->stats.write_hit),
3075 (unsigned) atomic_read(&cache->stats.write_miss),
3076 (unsigned) atomic_read(&cache->stats.demotion),
3077 (unsigned) atomic_read(&cache->stats.promotion),
3078 (unsigned long) atomic_read(&cache->nr_dirty));
3079
3080 emit_flags(cache, result, maxlen, &sz);
3081
3082 DMEMIT("2 migration_threshold %llu ", (unsigned long long) cache->migration_threshold);
3083
3084 DMEMIT("%s ", dm_cache_policy_get_name(cache->policy));
3085 if (sz < maxlen) {
3086 r = policy_emit_config_values(cache->policy, result, maxlen, &sz);
3087 if (r)
3088 DMERR("%s: policy_emit_config_values returned %d",
3089 cache_device_name(cache), r);
3090 }
3091
3092 if (get_cache_mode(cache) == CM_READ_ONLY)
3093 DMEMIT("ro ");
3094 else
3095 DMEMIT("rw ");
3096
3097 r = dm_cache_metadata_needs_check(cache->cmd, &needs_check);
3098
3099 if (r || needs_check)
3100 DMEMIT("needs_check ");
3101 else
3102 DMEMIT("- ");
3103
3104 break;
3105
3106 case STATUSTYPE_TABLE:
3107 format_dev_t(buf, cache->metadata_dev->bdev->bd_dev);
3108 DMEMIT("%s ", buf);
3109 format_dev_t(buf, cache->cache_dev->bdev->bd_dev);
3110 DMEMIT("%s ", buf);
3111 format_dev_t(buf, cache->origin_dev->bdev->bd_dev);
3112 DMEMIT("%s", buf);
3113
3114 for (i = 0; i < cache->nr_ctr_args - 1; i++)
3115 DMEMIT(" %s", cache->ctr_args[i]);
3116 if (cache->nr_ctr_args)
3117 DMEMIT(" %s", cache->ctr_args[cache->nr_ctr_args - 1]);
3118 break;
3119
3120 case STATUSTYPE_IMA:
3121 DMEMIT_TARGET_NAME_VERSION(ti->type);
3122 if (get_cache_mode(cache) == CM_FAIL)
3123 DMEMIT(",metadata_mode=fail");
3124 else if (get_cache_mode(cache) == CM_READ_ONLY)
3125 DMEMIT(",metadata_mode=ro");
3126 else
3127 DMEMIT(",metadata_mode=rw");
3128
3129 format_dev_t(buf, cache->metadata_dev->bdev->bd_dev);
3130 DMEMIT(",cache_metadata_device=%s", buf);
3131 format_dev_t(buf, cache->cache_dev->bdev->bd_dev);
3132 DMEMIT(",cache_device=%s", buf);
3133 format_dev_t(buf, cache->origin_dev->bdev->bd_dev);
3134 DMEMIT(",cache_origin_device=%s", buf);
3135 DMEMIT(",writethrough=%c", writethrough_mode(cache) ? 'y' : 'n');
3136 DMEMIT(",writeback=%c", writeback_mode(cache) ? 'y' : 'n');
3137 DMEMIT(",passthrough=%c", passthrough_mode(cache) ? 'y' : 'n');
3138 DMEMIT(",metadata2=%c", cache->features.metadata_version == 2 ? 'y' : 'n');
3139 DMEMIT(",no_discard_passdown=%c", cache->features.discard_passdown ? 'n' : 'y');
3140 DMEMIT(";");
3141 break;
3142 }
3143
3144 return;
3145
3146err:
3147 DMEMIT("Error");
3148}
3149
3150/*
3151 * Defines a range of cblocks, begin to (end - 1) are in the range. end is
3152 * the one-past-the-end value.
3153 */
3154struct cblock_range {
3155 dm_cblock_t begin;
3156 dm_cblock_t end;
3157};
3158
3159/*
3160 * A cache block range can take two forms:
3161 *
3162 * i) A single cblock, eg. '3456'
3163 * ii) A begin and end cblock with a dash between, eg. 123-234
3164 */
3165static int parse_cblock_range(struct cache *cache, const char *str,
3166 struct cblock_range *result)
3167{
3168 char dummy;
3169 uint64_t b, e;
3170 int r;
3171
3172 /*
3173 * Try and parse form (ii) first.
3174 */
3175 r = sscanf(str, "%llu-%llu%c", &b, &e, &dummy);
3176 if (r < 0)
3177 return r;
3178
3179 if (r == 2) {
3180 result->begin = to_cblock(b);
3181 result->end = to_cblock(e);
3182 return 0;
3183 }
3184
3185 /*
3186 * That didn't work, try form (i).
3187 */
3188 r = sscanf(str, "%llu%c", &b, &dummy);
3189 if (r < 0)
3190 return r;
3191
3192 if (r == 1) {
3193 result->begin = to_cblock(b);
3194 result->end = to_cblock(from_cblock(result->begin) + 1u);
3195 return 0;
3196 }
3197
3198 DMERR("%s: invalid cblock range '%s'", cache_device_name(cache), str);
3199 return -EINVAL;
3200}
3201
3202static int validate_cblock_range(struct cache *cache, struct cblock_range *range)
3203{
3204 uint64_t b = from_cblock(range->begin);
3205 uint64_t e = from_cblock(range->end);
3206 uint64_t n = from_cblock(cache->cache_size);
3207
3208 if (b >= n) {
3209 DMERR("%s: begin cblock out of range: %llu >= %llu",
3210 cache_device_name(cache), b, n);
3211 return -EINVAL;
3212 }
3213
3214 if (e > n) {
3215 DMERR("%s: end cblock out of range: %llu > %llu",
3216 cache_device_name(cache), e, n);
3217 return -EINVAL;
3218 }
3219
3220 if (b >= e) {
3221 DMERR("%s: invalid cblock range: %llu >= %llu",
3222 cache_device_name(cache), b, e);
3223 return -EINVAL;
3224 }
3225
3226 return 0;
3227}
3228
3229static inline dm_cblock_t cblock_succ(dm_cblock_t b)
3230{
3231 return to_cblock(from_cblock(b) + 1);
3232}
3233
3234static int request_invalidation(struct cache *cache, struct cblock_range *range)
3235{
3236 int r = 0;
3237
3238 /*
3239 * We don't need to do any locking here because we know we're in
3240 * passthrough mode. There's is potential for a race between an
3241 * invalidation triggered by an io and an invalidation message. This
3242 * is harmless, we must not worry if the policy call fails.
3243 */
3244 while (range->begin != range->end) {
3245 r = invalidate_cblock(cache, range->begin);
3246 if (r)
3247 return r;
3248
3249 range->begin = cblock_succ(range->begin);
3250 }
3251
3252 cache->commit_requested = true;
3253 return r;
3254}
3255
3256static int process_invalidate_cblocks_message(struct cache *cache, unsigned count,
3257 const char **cblock_ranges)
3258{
3259 int r = 0;
3260 unsigned i;
3261 struct cblock_range range;
3262
3263 if (!passthrough_mode(cache)) {
3264 DMERR("%s: cache has to be in passthrough mode for invalidation",
3265 cache_device_name(cache));
3266 return -EPERM;
3267 }
3268
3269 for (i = 0; i < count; i++) {
3270 r = parse_cblock_range(cache, cblock_ranges[i], &range);
3271 if (r)
3272 break;
3273
3274 r = validate_cblock_range(cache, &range);
3275 if (r)
3276 break;
3277
3278 /*
3279 * Pass begin and end origin blocks to the worker and wake it.
3280 */
3281 r = request_invalidation(cache, &range);
3282 if (r)
3283 break;
3284 }
3285
3286 return r;
3287}
3288
3289/*
3290 * Supports
3291 * "<key> <value>"
3292 * and
3293 * "invalidate_cblocks [(<begin>)|(<begin>-<end>)]*
3294 *
3295 * The key migration_threshold is supported by the cache target core.
3296 */
3297static int cache_message(struct dm_target *ti, unsigned argc, char **argv,
3298 char *result, unsigned maxlen)
3299{
3300 struct cache *cache = ti->private;
3301
3302 if (!argc)
3303 return -EINVAL;
3304
3305 if (get_cache_mode(cache) >= CM_READ_ONLY) {
3306 DMERR("%s: unable to service cache target messages in READ_ONLY or FAIL mode",
3307 cache_device_name(cache));
3308 return -EOPNOTSUPP;
3309 }
3310
3311 if (!strcasecmp(argv[0], "invalidate_cblocks"))
3312 return process_invalidate_cblocks_message(cache, argc - 1, (const char **) argv + 1);
3313
3314 if (argc != 2)
3315 return -EINVAL;
3316
3317 return set_config_value(cache, argv[0], argv[1]);
3318}
3319
3320static int cache_iterate_devices(struct dm_target *ti,
3321 iterate_devices_callout_fn fn, void *data)
3322{
3323 int r = 0;
3324 struct cache *cache = ti->private;
3325
3326 r = fn(ti, cache->cache_dev, 0, get_dev_size(cache->cache_dev), data);
3327 if (!r)
3328 r = fn(ti, cache->origin_dev, 0, ti->len, data);
3329
3330 return r;
3331}
3332
3333/*
3334 * If discard_passdown was enabled verify that the origin device
3335 * supports discards. Disable discard_passdown if not.
3336 */
3337static void disable_passdown_if_not_supported(struct cache *cache)
3338{
3339 struct block_device *origin_bdev = cache->origin_dev->bdev;
3340 struct queue_limits *origin_limits = &bdev_get_queue(origin_bdev)->limits;
3341 const char *reason = NULL;
3342
3343 if (!cache->features.discard_passdown)
3344 return;
3345
3346 if (!bdev_max_discard_sectors(origin_bdev))
3347 reason = "discard unsupported";
3348
3349 else if (origin_limits->max_discard_sectors < cache->sectors_per_block)
3350 reason = "max discard sectors smaller than a block";
3351
3352 if (reason) {
3353 DMWARN("Origin device (%pg) %s: Disabling discard passdown.",
3354 origin_bdev, reason);
3355 cache->features.discard_passdown = false;
3356 }
3357}
3358
3359static void set_discard_limits(struct cache *cache, struct queue_limits *limits)
3360{
3361 struct block_device *origin_bdev = cache->origin_dev->bdev;
3362 struct queue_limits *origin_limits = &bdev_get_queue(origin_bdev)->limits;
3363
3364 if (!cache->features.discard_passdown) {
3365 /* No passdown is done so setting own virtual limits */
3366 limits->max_discard_sectors = min_t(sector_t, cache->discard_block_size * 1024,
3367 cache->origin_sectors);
3368 limits->discard_granularity = cache->discard_block_size << SECTOR_SHIFT;
3369 return;
3370 }
3371
3372 /*
3373 * cache_iterate_devices() is stacking both origin and fast device limits
3374 * but discards aren't passed to fast device, so inherit origin's limits.
3375 */
3376 limits->max_discard_sectors = origin_limits->max_discard_sectors;
3377 limits->max_hw_discard_sectors = origin_limits->max_hw_discard_sectors;
3378 limits->discard_granularity = origin_limits->discard_granularity;
3379 limits->discard_alignment = origin_limits->discard_alignment;
3380 limits->discard_misaligned = origin_limits->discard_misaligned;
3381}
3382
3383static void cache_io_hints(struct dm_target *ti, struct queue_limits *limits)
3384{
3385 struct cache *cache = ti->private;
3386 uint64_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;
3387
3388 /*
3389 * If the system-determined stacked limits are compatible with the
3390 * cache's blocksize (io_opt is a factor) do not override them.
3391 */
3392 if (io_opt_sectors < cache->sectors_per_block ||
3393 do_div(io_opt_sectors, cache->sectors_per_block)) {
3394 blk_limits_io_min(limits, cache->sectors_per_block << SECTOR_SHIFT);
3395 blk_limits_io_opt(limits, cache->sectors_per_block << SECTOR_SHIFT);
3396 }
3397
3398 disable_passdown_if_not_supported(cache);
3399 set_discard_limits(cache, limits);
3400}
3401
3402/*----------------------------------------------------------------*/
3403
3404static struct target_type cache_target = {
3405 .name = "cache",
3406 .version = {2, 2, 0},
3407 .module = THIS_MODULE,
3408 .ctr = cache_ctr,
3409 .dtr = cache_dtr,
3410 .map = cache_map,
3411 .end_io = cache_end_io,
3412 .postsuspend = cache_postsuspend,
3413 .preresume = cache_preresume,
3414 .resume = cache_resume,
3415 .status = cache_status,
3416 .message = cache_message,
3417 .iterate_devices = cache_iterate_devices,
3418 .io_hints = cache_io_hints,
3419};
3420
3421static int __init dm_cache_init(void)
3422{
3423 int r;
3424
3425 migration_cache = KMEM_CACHE(dm_cache_migration, 0);
3426 if (!migration_cache)
3427 return -ENOMEM;
3428
3429 r = dm_register_target(&cache_target);
3430 if (r) {
3431 DMERR("cache target registration failed: %d", r);
3432 kmem_cache_destroy(migration_cache);
3433 return r;
3434 }
3435
3436 return 0;
3437}
3438
3439static void __exit dm_cache_exit(void)
3440{
3441 dm_unregister_target(&cache_target);
3442 kmem_cache_destroy(migration_cache);
3443}
3444
3445module_init(dm_cache_init);
3446module_exit(dm_cache_exit);
3447
3448MODULE_DESCRIPTION(DM_NAME " cache target");
3449MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
3450MODULE_LICENSE("GPL");
1/*
2 * Copyright (C) 2012 Red Hat. All rights reserved.
3 *
4 * This file is released under the GPL.
5 */
6
7#include "dm.h"
8#include "dm-bio-prison-v2.h"
9#include "dm-bio-record.h"
10#include "dm-cache-metadata.h"
11
12#include <linux/dm-io.h>
13#include <linux/dm-kcopyd.h>
14#include <linux/jiffies.h>
15#include <linux/init.h>
16#include <linux/mempool.h>
17#include <linux/module.h>
18#include <linux/rwsem.h>
19#include <linux/slab.h>
20#include <linux/vmalloc.h>
21
22#define DM_MSG_PREFIX "cache"
23
24DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(cache_copy_throttle,
25 "A percentage of time allocated for copying to and/or from cache");
26
27/*----------------------------------------------------------------*/
28
29/*
30 * Glossary:
31 *
32 * oblock: index of an origin block
33 * cblock: index of a cache block
34 * promotion: movement of a block from origin to cache
35 * demotion: movement of a block from cache to origin
36 * migration: movement of a block between the origin and cache device,
37 * either direction
38 */
39
40/*----------------------------------------------------------------*/
41
42struct io_tracker {
43 spinlock_t lock;
44
45 /*
46 * Sectors of in-flight IO.
47 */
48 sector_t in_flight;
49
50 /*
51 * The time, in jiffies, when this device became idle (if it is
52 * indeed idle).
53 */
54 unsigned long idle_time;
55 unsigned long last_update_time;
56};
57
58static void iot_init(struct io_tracker *iot)
59{
60 spin_lock_init(&iot->lock);
61 iot->in_flight = 0ul;
62 iot->idle_time = 0ul;
63 iot->last_update_time = jiffies;
64}
65
66static bool __iot_idle_for(struct io_tracker *iot, unsigned long jifs)
67{
68 if (iot->in_flight)
69 return false;
70
71 return time_after(jiffies, iot->idle_time + jifs);
72}
73
74static bool iot_idle_for(struct io_tracker *iot, unsigned long jifs)
75{
76 bool r;
77 unsigned long flags;
78
79 spin_lock_irqsave(&iot->lock, flags);
80 r = __iot_idle_for(iot, jifs);
81 spin_unlock_irqrestore(&iot->lock, flags);
82
83 return r;
84}
85
86static void iot_io_begin(struct io_tracker *iot, sector_t len)
87{
88 unsigned long flags;
89
90 spin_lock_irqsave(&iot->lock, flags);
91 iot->in_flight += len;
92 spin_unlock_irqrestore(&iot->lock, flags);
93}
94
95static void __iot_io_end(struct io_tracker *iot, sector_t len)
96{
97 if (!len)
98 return;
99
100 iot->in_flight -= len;
101 if (!iot->in_flight)
102 iot->idle_time = jiffies;
103}
104
105static void iot_io_end(struct io_tracker *iot, sector_t len)
106{
107 unsigned long flags;
108
109 spin_lock_irqsave(&iot->lock, flags);
110 __iot_io_end(iot, len);
111 spin_unlock_irqrestore(&iot->lock, flags);
112}
113
114/*----------------------------------------------------------------*/
115
116/*
117 * Represents a chunk of future work. 'input' allows continuations to pass
118 * values between themselves, typically error values.
119 */
120struct continuation {
121 struct work_struct ws;
122 blk_status_t input;
123};
124
125static inline void init_continuation(struct continuation *k,
126 void (*fn)(struct work_struct *))
127{
128 INIT_WORK(&k->ws, fn);
129 k->input = 0;
130}
131
132static inline void queue_continuation(struct workqueue_struct *wq,
133 struct continuation *k)
134{
135 queue_work(wq, &k->ws);
136}
137
138/*----------------------------------------------------------------*/
139
140/*
141 * The batcher collects together pieces of work that need a particular
142 * operation to occur before they can proceed (typically a commit).
143 */
144struct batcher {
145 /*
146 * The operation that everyone is waiting for.
147 */
148 blk_status_t (*commit_op)(void *context);
149 void *commit_context;
150
151 /*
152 * This is how bios should be issued once the commit op is complete
153 * (accounted_request).
154 */
155 void (*issue_op)(struct bio *bio, void *context);
156 void *issue_context;
157
158 /*
159 * Queued work gets put on here after commit.
160 */
161 struct workqueue_struct *wq;
162
163 spinlock_t lock;
164 struct list_head work_items;
165 struct bio_list bios;
166 struct work_struct commit_work;
167
168 bool commit_scheduled;
169};
170
171static void __commit(struct work_struct *_ws)
172{
173 struct batcher *b = container_of(_ws, struct batcher, commit_work);
174 blk_status_t r;
175 unsigned long flags;
176 struct list_head work_items;
177 struct work_struct *ws, *tmp;
178 struct continuation *k;
179 struct bio *bio;
180 struct bio_list bios;
181
182 INIT_LIST_HEAD(&work_items);
183 bio_list_init(&bios);
184
185 /*
186 * We have to grab these before the commit_op to avoid a race
187 * condition.
188 */
189 spin_lock_irqsave(&b->lock, flags);
190 list_splice_init(&b->work_items, &work_items);
191 bio_list_merge(&bios, &b->bios);
192 bio_list_init(&b->bios);
193 b->commit_scheduled = false;
194 spin_unlock_irqrestore(&b->lock, flags);
195
196 r = b->commit_op(b->commit_context);
197
198 list_for_each_entry_safe(ws, tmp, &work_items, entry) {
199 k = container_of(ws, struct continuation, ws);
200 k->input = r;
201 INIT_LIST_HEAD(&ws->entry); /* to avoid a WARN_ON */
202 queue_work(b->wq, ws);
203 }
204
205 while ((bio = bio_list_pop(&bios))) {
206 if (r) {
207 bio->bi_status = r;
208 bio_endio(bio);
209 } else
210 b->issue_op(bio, b->issue_context);
211 }
212}
213
214static void batcher_init(struct batcher *b,
215 blk_status_t (*commit_op)(void *),
216 void *commit_context,
217 void (*issue_op)(struct bio *bio, void *),
218 void *issue_context,
219 struct workqueue_struct *wq)
220{
221 b->commit_op = commit_op;
222 b->commit_context = commit_context;
223 b->issue_op = issue_op;
224 b->issue_context = issue_context;
225 b->wq = wq;
226
227 spin_lock_init(&b->lock);
228 INIT_LIST_HEAD(&b->work_items);
229 bio_list_init(&b->bios);
230 INIT_WORK(&b->commit_work, __commit);
231 b->commit_scheduled = false;
232}
233
234static void async_commit(struct batcher *b)
235{
236 queue_work(b->wq, &b->commit_work);
237}
238
239static void continue_after_commit(struct batcher *b, struct continuation *k)
240{
241 unsigned long flags;
242 bool commit_scheduled;
243
244 spin_lock_irqsave(&b->lock, flags);
245 commit_scheduled = b->commit_scheduled;
246 list_add_tail(&k->ws.entry, &b->work_items);
247 spin_unlock_irqrestore(&b->lock, flags);
248
249 if (commit_scheduled)
250 async_commit(b);
251}
252
253/*
254 * Bios are errored if commit failed.
255 */
256static void issue_after_commit(struct batcher *b, struct bio *bio)
257{
258 unsigned long flags;
259 bool commit_scheduled;
260
261 spin_lock_irqsave(&b->lock, flags);
262 commit_scheduled = b->commit_scheduled;
263 bio_list_add(&b->bios, bio);
264 spin_unlock_irqrestore(&b->lock, flags);
265
266 if (commit_scheduled)
267 async_commit(b);
268}
269
270/*
271 * Call this if some urgent work is waiting for the commit to complete.
272 */
273static void schedule_commit(struct batcher *b)
274{
275 bool immediate;
276 unsigned long flags;
277
278 spin_lock_irqsave(&b->lock, flags);
279 immediate = !list_empty(&b->work_items) || !bio_list_empty(&b->bios);
280 b->commit_scheduled = true;
281 spin_unlock_irqrestore(&b->lock, flags);
282
283 if (immediate)
284 async_commit(b);
285}
286
287/*
288 * There are a couple of places where we let a bio run, but want to do some
289 * work before calling its endio function. We do this by temporarily
290 * changing the endio fn.
291 */
292struct dm_hook_info {
293 bio_end_io_t *bi_end_io;
294};
295
296static void dm_hook_bio(struct dm_hook_info *h, struct bio *bio,
297 bio_end_io_t *bi_end_io, void *bi_private)
298{
299 h->bi_end_io = bio->bi_end_io;
300
301 bio->bi_end_io = bi_end_io;
302 bio->bi_private = bi_private;
303}
304
305static void dm_unhook_bio(struct dm_hook_info *h, struct bio *bio)
306{
307 bio->bi_end_io = h->bi_end_io;
308}
309
310/*----------------------------------------------------------------*/
311
312#define MIGRATION_POOL_SIZE 128
313#define COMMIT_PERIOD HZ
314#define MIGRATION_COUNT_WINDOW 10
315
316/*
317 * The block size of the device holding cache data must be
318 * between 32KB and 1GB.
319 */
320#define DATA_DEV_BLOCK_SIZE_MIN_SECTORS (32 * 1024 >> SECTOR_SHIFT)
321#define DATA_DEV_BLOCK_SIZE_MAX_SECTORS (1024 * 1024 * 1024 >> SECTOR_SHIFT)
322
323enum cache_metadata_mode {
324 CM_WRITE, /* metadata may be changed */
325 CM_READ_ONLY, /* metadata may not be changed */
326 CM_FAIL
327};
328
329enum cache_io_mode {
330 /*
331 * Data is written to cached blocks only. These blocks are marked
332 * dirty. If you lose the cache device you will lose data.
333 * Potential performance increase for both reads and writes.
334 */
335 CM_IO_WRITEBACK,
336
337 /*
338 * Data is written to both cache and origin. Blocks are never
339 * dirty. Potential performance benfit for reads only.
340 */
341 CM_IO_WRITETHROUGH,
342
343 /*
344 * A degraded mode useful for various cache coherency situations
345 * (eg, rolling back snapshots). Reads and writes always go to the
346 * origin. If a write goes to a cached oblock, then the cache
347 * block is invalidated.
348 */
349 CM_IO_PASSTHROUGH
350};
351
352struct cache_features {
353 enum cache_metadata_mode mode;
354 enum cache_io_mode io_mode;
355 unsigned metadata_version;
356};
357
358struct cache_stats {
359 atomic_t read_hit;
360 atomic_t read_miss;
361 atomic_t write_hit;
362 atomic_t write_miss;
363 atomic_t demotion;
364 atomic_t promotion;
365 atomic_t writeback;
366 atomic_t copies_avoided;
367 atomic_t cache_cell_clash;
368 atomic_t commit_count;
369 atomic_t discard_count;
370};
371
372struct cache {
373 struct dm_target *ti;
374 struct dm_target_callbacks callbacks;
375
376 struct dm_cache_metadata *cmd;
377
378 /*
379 * Metadata is written to this device.
380 */
381 struct dm_dev *metadata_dev;
382
383 /*
384 * The slower of the two data devices. Typically a spindle.
385 */
386 struct dm_dev *origin_dev;
387
388 /*
389 * The faster of the two data devices. Typically an SSD.
390 */
391 struct dm_dev *cache_dev;
392
393 /*
394 * Size of the origin device in _complete_ blocks and native sectors.
395 */
396 dm_oblock_t origin_blocks;
397 sector_t origin_sectors;
398
399 /*
400 * Size of the cache device in blocks.
401 */
402 dm_cblock_t cache_size;
403
404 /*
405 * Fields for converting from sectors to blocks.
406 */
407 sector_t sectors_per_block;
408 int sectors_per_block_shift;
409
410 spinlock_t lock;
411 struct bio_list deferred_bios;
412 sector_t migration_threshold;
413 wait_queue_head_t migration_wait;
414 atomic_t nr_allocated_migrations;
415
416 /*
417 * The number of in flight migrations that are performing
418 * background io. eg, promotion, writeback.
419 */
420 atomic_t nr_io_migrations;
421
422 struct rw_semaphore quiesce_lock;
423
424 /*
425 * cache_size entries, dirty if set
426 */
427 atomic_t nr_dirty;
428 unsigned long *dirty_bitset;
429
430 /*
431 * origin_blocks entries, discarded if set.
432 */
433 dm_dblock_t discard_nr_blocks;
434 unsigned long *discard_bitset;
435 uint32_t discard_block_size; /* a power of 2 times sectors per block */
436
437 /*
438 * Rather than reconstructing the table line for the status we just
439 * save it and regurgitate.
440 */
441 unsigned nr_ctr_args;
442 const char **ctr_args;
443
444 struct dm_kcopyd_client *copier;
445 struct workqueue_struct *wq;
446 struct work_struct deferred_bio_worker;
447 struct work_struct migration_worker;
448 struct delayed_work waker;
449 struct dm_bio_prison_v2 *prison;
450 struct bio_set *bs;
451
452 mempool_t *migration_pool;
453
454 struct dm_cache_policy *policy;
455 unsigned policy_nr_args;
456
457 bool need_tick_bio:1;
458 bool sized:1;
459 bool invalidate:1;
460 bool commit_requested:1;
461 bool loaded_mappings:1;
462 bool loaded_discards:1;
463
464 /*
465 * Cache features such as write-through.
466 */
467 struct cache_features features;
468
469 struct cache_stats stats;
470
471 /*
472 * Invalidation fields.
473 */
474 spinlock_t invalidation_lock;
475 struct list_head invalidation_requests;
476
477 struct io_tracker tracker;
478
479 struct work_struct commit_ws;
480 struct batcher committer;
481
482 struct rw_semaphore background_work_lock;
483};
484
485struct per_bio_data {
486 bool tick:1;
487 unsigned req_nr:2;
488 struct dm_bio_prison_cell_v2 *cell;
489 struct dm_hook_info hook_info;
490 sector_t len;
491};
492
493struct dm_cache_migration {
494 struct continuation k;
495 struct cache *cache;
496
497 struct policy_work *op;
498 struct bio *overwrite_bio;
499 struct dm_bio_prison_cell_v2 *cell;
500
501 dm_cblock_t invalidate_cblock;
502 dm_oblock_t invalidate_oblock;
503};
504
505/*----------------------------------------------------------------*/
506
507static bool writethrough_mode(struct cache *cache)
508{
509 return cache->features.io_mode == CM_IO_WRITETHROUGH;
510}
511
512static bool writeback_mode(struct cache *cache)
513{
514 return cache->features.io_mode == CM_IO_WRITEBACK;
515}
516
517static inline bool passthrough_mode(struct cache *cache)
518{
519 return unlikely(cache->features.io_mode == CM_IO_PASSTHROUGH);
520}
521
522/*----------------------------------------------------------------*/
523
524static void wake_deferred_bio_worker(struct cache *cache)
525{
526 queue_work(cache->wq, &cache->deferred_bio_worker);
527}
528
529static void wake_migration_worker(struct cache *cache)
530{
531 if (passthrough_mode(cache))
532 return;
533
534 queue_work(cache->wq, &cache->migration_worker);
535}
536
537/*----------------------------------------------------------------*/
538
539static struct dm_bio_prison_cell_v2 *alloc_prison_cell(struct cache *cache)
540{
541 return dm_bio_prison_alloc_cell_v2(cache->prison, GFP_NOWAIT);
542}
543
544static void free_prison_cell(struct cache *cache, struct dm_bio_prison_cell_v2 *cell)
545{
546 dm_bio_prison_free_cell_v2(cache->prison, cell);
547}
548
549static struct dm_cache_migration *alloc_migration(struct cache *cache)
550{
551 struct dm_cache_migration *mg;
552
553 mg = mempool_alloc(cache->migration_pool, GFP_NOWAIT);
554 if (!mg)
555 return NULL;
556
557 memset(mg, 0, sizeof(*mg));
558
559 mg->cache = cache;
560 atomic_inc(&cache->nr_allocated_migrations);
561
562 return mg;
563}
564
565static void free_migration(struct dm_cache_migration *mg)
566{
567 struct cache *cache = mg->cache;
568
569 if (atomic_dec_and_test(&cache->nr_allocated_migrations))
570 wake_up(&cache->migration_wait);
571
572 mempool_free(mg, cache->migration_pool);
573}
574
575/*----------------------------------------------------------------*/
576
577static inline dm_oblock_t oblock_succ(dm_oblock_t b)
578{
579 return to_oblock(from_oblock(b) + 1ull);
580}
581
582static void build_key(dm_oblock_t begin, dm_oblock_t end, struct dm_cell_key_v2 *key)
583{
584 key->virtual = 0;
585 key->dev = 0;
586 key->block_begin = from_oblock(begin);
587 key->block_end = from_oblock(end);
588}
589
590/*
591 * We have two lock levels. Level 0, which is used to prevent WRITEs, and
592 * level 1 which prevents *both* READs and WRITEs.
593 */
594#define WRITE_LOCK_LEVEL 0
595#define READ_WRITE_LOCK_LEVEL 1
596
597static unsigned lock_level(struct bio *bio)
598{
599 return bio_data_dir(bio) == WRITE ?
600 WRITE_LOCK_LEVEL :
601 READ_WRITE_LOCK_LEVEL;
602}
603
604/*----------------------------------------------------------------
605 * Per bio data
606 *--------------------------------------------------------------*/
607
608static struct per_bio_data *get_per_bio_data(struct bio *bio)
609{
610 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
611 BUG_ON(!pb);
612 return pb;
613}
614
615static struct per_bio_data *init_per_bio_data(struct bio *bio)
616{
617 struct per_bio_data *pb = get_per_bio_data(bio);
618
619 pb->tick = false;
620 pb->req_nr = dm_bio_get_target_bio_nr(bio);
621 pb->cell = NULL;
622 pb->len = 0;
623
624 return pb;
625}
626
627/*----------------------------------------------------------------*/
628
629static void defer_bio(struct cache *cache, struct bio *bio)
630{
631 unsigned long flags;
632
633 spin_lock_irqsave(&cache->lock, flags);
634 bio_list_add(&cache->deferred_bios, bio);
635 spin_unlock_irqrestore(&cache->lock, flags);
636
637 wake_deferred_bio_worker(cache);
638}
639
640static void defer_bios(struct cache *cache, struct bio_list *bios)
641{
642 unsigned long flags;
643
644 spin_lock_irqsave(&cache->lock, flags);
645 bio_list_merge(&cache->deferred_bios, bios);
646 bio_list_init(bios);
647 spin_unlock_irqrestore(&cache->lock, flags);
648
649 wake_deferred_bio_worker(cache);
650}
651
652/*----------------------------------------------------------------*/
653
654static bool bio_detain_shared(struct cache *cache, dm_oblock_t oblock, struct bio *bio)
655{
656 bool r;
657 struct per_bio_data *pb;
658 struct dm_cell_key_v2 key;
659 dm_oblock_t end = to_oblock(from_oblock(oblock) + 1ULL);
660 struct dm_bio_prison_cell_v2 *cell_prealloc, *cell;
661
662 cell_prealloc = alloc_prison_cell(cache); /* FIXME: allow wait if calling from worker */
663 if (!cell_prealloc) {
664 defer_bio(cache, bio);
665 return false;
666 }
667
668 build_key(oblock, end, &key);
669 r = dm_cell_get_v2(cache->prison, &key, lock_level(bio), bio, cell_prealloc, &cell);
670 if (!r) {
671 /*
672 * Failed to get the lock.
673 */
674 free_prison_cell(cache, cell_prealloc);
675 return r;
676 }
677
678 if (cell != cell_prealloc)
679 free_prison_cell(cache, cell_prealloc);
680
681 pb = get_per_bio_data(bio);
682 pb->cell = cell;
683
684 return r;
685}
686
687/*----------------------------------------------------------------*/
688
689static bool is_dirty(struct cache *cache, dm_cblock_t b)
690{
691 return test_bit(from_cblock(b), cache->dirty_bitset);
692}
693
694static void set_dirty(struct cache *cache, dm_cblock_t cblock)
695{
696 if (!test_and_set_bit(from_cblock(cblock), cache->dirty_bitset)) {
697 atomic_inc(&cache->nr_dirty);
698 policy_set_dirty(cache->policy, cblock);
699 }
700}
701
702/*
703 * These two are called when setting after migrations to force the policy
704 * and dirty bitset to be in sync.
705 */
706static void force_set_dirty(struct cache *cache, dm_cblock_t cblock)
707{
708 if (!test_and_set_bit(from_cblock(cblock), cache->dirty_bitset))
709 atomic_inc(&cache->nr_dirty);
710 policy_set_dirty(cache->policy, cblock);
711}
712
713static void force_clear_dirty(struct cache *cache, dm_cblock_t cblock)
714{
715 if (test_and_clear_bit(from_cblock(cblock), cache->dirty_bitset)) {
716 if (atomic_dec_return(&cache->nr_dirty) == 0)
717 dm_table_event(cache->ti->table);
718 }
719
720 policy_clear_dirty(cache->policy, cblock);
721}
722
723/*----------------------------------------------------------------*/
724
725static bool block_size_is_power_of_two(struct cache *cache)
726{
727 return cache->sectors_per_block_shift >= 0;
728}
729
730/* gcc on ARM generates spurious references to __udivdi3 and __umoddi3 */
731#if defined(CONFIG_ARM) && __GNUC__ == 4 && __GNUC_MINOR__ <= 6
732__always_inline
733#endif
734static dm_block_t block_div(dm_block_t b, uint32_t n)
735{
736 do_div(b, n);
737
738 return b;
739}
740
741static dm_block_t oblocks_per_dblock(struct cache *cache)
742{
743 dm_block_t oblocks = cache->discard_block_size;
744
745 if (block_size_is_power_of_two(cache))
746 oblocks >>= cache->sectors_per_block_shift;
747 else
748 oblocks = block_div(oblocks, cache->sectors_per_block);
749
750 return oblocks;
751}
752
753static dm_dblock_t oblock_to_dblock(struct cache *cache, dm_oblock_t oblock)
754{
755 return to_dblock(block_div(from_oblock(oblock),
756 oblocks_per_dblock(cache)));
757}
758
759static void set_discard(struct cache *cache, dm_dblock_t b)
760{
761 unsigned long flags;
762
763 BUG_ON(from_dblock(b) >= from_dblock(cache->discard_nr_blocks));
764 atomic_inc(&cache->stats.discard_count);
765
766 spin_lock_irqsave(&cache->lock, flags);
767 set_bit(from_dblock(b), cache->discard_bitset);
768 spin_unlock_irqrestore(&cache->lock, flags);
769}
770
771static void clear_discard(struct cache *cache, dm_dblock_t b)
772{
773 unsigned long flags;
774
775 spin_lock_irqsave(&cache->lock, flags);
776 clear_bit(from_dblock(b), cache->discard_bitset);
777 spin_unlock_irqrestore(&cache->lock, flags);
778}
779
780static bool is_discarded(struct cache *cache, dm_dblock_t b)
781{
782 int r;
783 unsigned long flags;
784
785 spin_lock_irqsave(&cache->lock, flags);
786 r = test_bit(from_dblock(b), cache->discard_bitset);
787 spin_unlock_irqrestore(&cache->lock, flags);
788
789 return r;
790}
791
792static bool is_discarded_oblock(struct cache *cache, dm_oblock_t b)
793{
794 int r;
795 unsigned long flags;
796
797 spin_lock_irqsave(&cache->lock, flags);
798 r = test_bit(from_dblock(oblock_to_dblock(cache, b)),
799 cache->discard_bitset);
800 spin_unlock_irqrestore(&cache->lock, flags);
801
802 return r;
803}
804
805/*----------------------------------------------------------------
806 * Remapping
807 *--------------------------------------------------------------*/
808static void remap_to_origin(struct cache *cache, struct bio *bio)
809{
810 bio_set_dev(bio, cache->origin_dev->bdev);
811}
812
813static void remap_to_cache(struct cache *cache, struct bio *bio,
814 dm_cblock_t cblock)
815{
816 sector_t bi_sector = bio->bi_iter.bi_sector;
817 sector_t block = from_cblock(cblock);
818
819 bio_set_dev(bio, cache->cache_dev->bdev);
820 if (!block_size_is_power_of_two(cache))
821 bio->bi_iter.bi_sector =
822 (block * cache->sectors_per_block) +
823 sector_div(bi_sector, cache->sectors_per_block);
824 else
825 bio->bi_iter.bi_sector =
826 (block << cache->sectors_per_block_shift) |
827 (bi_sector & (cache->sectors_per_block - 1));
828}
829
830static void check_if_tick_bio_needed(struct cache *cache, struct bio *bio)
831{
832 unsigned long flags;
833 struct per_bio_data *pb;
834
835 spin_lock_irqsave(&cache->lock, flags);
836 if (cache->need_tick_bio && !op_is_flush(bio->bi_opf) &&
837 bio_op(bio) != REQ_OP_DISCARD) {
838 pb = get_per_bio_data(bio);
839 pb->tick = true;
840 cache->need_tick_bio = false;
841 }
842 spin_unlock_irqrestore(&cache->lock, flags);
843}
844
845static void __remap_to_origin_clear_discard(struct cache *cache, struct bio *bio,
846 dm_oblock_t oblock, bool bio_has_pbd)
847{
848 if (bio_has_pbd)
849 check_if_tick_bio_needed(cache, bio);
850 remap_to_origin(cache, bio);
851 if (bio_data_dir(bio) == WRITE)
852 clear_discard(cache, oblock_to_dblock(cache, oblock));
853}
854
855static void remap_to_origin_clear_discard(struct cache *cache, struct bio *bio,
856 dm_oblock_t oblock)
857{
858 // FIXME: check_if_tick_bio_needed() is called way too much through this interface
859 __remap_to_origin_clear_discard(cache, bio, oblock, true);
860}
861
862static void remap_to_cache_dirty(struct cache *cache, struct bio *bio,
863 dm_oblock_t oblock, dm_cblock_t cblock)
864{
865 check_if_tick_bio_needed(cache, bio);
866 remap_to_cache(cache, bio, cblock);
867 if (bio_data_dir(bio) == WRITE) {
868 set_dirty(cache, cblock);
869 clear_discard(cache, oblock_to_dblock(cache, oblock));
870 }
871}
872
873static dm_oblock_t get_bio_block(struct cache *cache, struct bio *bio)
874{
875 sector_t block_nr = bio->bi_iter.bi_sector;
876
877 if (!block_size_is_power_of_two(cache))
878 (void) sector_div(block_nr, cache->sectors_per_block);
879 else
880 block_nr >>= cache->sectors_per_block_shift;
881
882 return to_oblock(block_nr);
883}
884
885static bool accountable_bio(struct cache *cache, struct bio *bio)
886{
887 return bio_op(bio) != REQ_OP_DISCARD;
888}
889
890static void accounted_begin(struct cache *cache, struct bio *bio)
891{
892 struct per_bio_data *pb;
893
894 if (accountable_bio(cache, bio)) {
895 pb = get_per_bio_data(bio);
896 pb->len = bio_sectors(bio);
897 iot_io_begin(&cache->tracker, pb->len);
898 }
899}
900
901static void accounted_complete(struct cache *cache, struct bio *bio)
902{
903 struct per_bio_data *pb = get_per_bio_data(bio);
904
905 iot_io_end(&cache->tracker, pb->len);
906}
907
908static void accounted_request(struct cache *cache, struct bio *bio)
909{
910 accounted_begin(cache, bio);
911 generic_make_request(bio);
912}
913
914static void issue_op(struct bio *bio, void *context)
915{
916 struct cache *cache = context;
917 accounted_request(cache, bio);
918}
919
920/*
921 * When running in writethrough mode we need to send writes to clean blocks
922 * to both the cache and origin devices. Clone the bio and send them in parallel.
923 */
924static void remap_to_origin_and_cache(struct cache *cache, struct bio *bio,
925 dm_oblock_t oblock, dm_cblock_t cblock)
926{
927 struct bio *origin_bio = bio_clone_fast(bio, GFP_NOIO, cache->bs);
928
929 BUG_ON(!origin_bio);
930
931 bio_chain(origin_bio, bio);
932 /*
933 * Passing false to __remap_to_origin_clear_discard() skips
934 * all code that might use per_bio_data (since clone doesn't have it)
935 */
936 __remap_to_origin_clear_discard(cache, origin_bio, oblock, false);
937 submit_bio(origin_bio);
938
939 remap_to_cache(cache, bio, cblock);
940}
941
942/*----------------------------------------------------------------
943 * Failure modes
944 *--------------------------------------------------------------*/
945static enum cache_metadata_mode get_cache_mode(struct cache *cache)
946{
947 return cache->features.mode;
948}
949
950static const char *cache_device_name(struct cache *cache)
951{
952 return dm_device_name(dm_table_get_md(cache->ti->table));
953}
954
955static void notify_mode_switch(struct cache *cache, enum cache_metadata_mode mode)
956{
957 const char *descs[] = {
958 "write",
959 "read-only",
960 "fail"
961 };
962
963 dm_table_event(cache->ti->table);
964 DMINFO("%s: switching cache to %s mode",
965 cache_device_name(cache), descs[(int)mode]);
966}
967
968static void set_cache_mode(struct cache *cache, enum cache_metadata_mode new_mode)
969{
970 bool needs_check;
971 enum cache_metadata_mode old_mode = get_cache_mode(cache);
972
973 if (dm_cache_metadata_needs_check(cache->cmd, &needs_check)) {
974 DMERR("%s: unable to read needs_check flag, setting failure mode.",
975 cache_device_name(cache));
976 new_mode = CM_FAIL;
977 }
978
979 if (new_mode == CM_WRITE && needs_check) {
980 DMERR("%s: unable to switch cache to write mode until repaired.",
981 cache_device_name(cache));
982 if (old_mode != new_mode)
983 new_mode = old_mode;
984 else
985 new_mode = CM_READ_ONLY;
986 }
987
988 /* Never move out of fail mode */
989 if (old_mode == CM_FAIL)
990 new_mode = CM_FAIL;
991
992 switch (new_mode) {
993 case CM_FAIL:
994 case CM_READ_ONLY:
995 dm_cache_metadata_set_read_only(cache->cmd);
996 break;
997
998 case CM_WRITE:
999 dm_cache_metadata_set_read_write(cache->cmd);
1000 break;
1001 }
1002
1003 cache->features.mode = new_mode;
1004
1005 if (new_mode != old_mode)
1006 notify_mode_switch(cache, new_mode);
1007}
1008
1009static void abort_transaction(struct cache *cache)
1010{
1011 const char *dev_name = cache_device_name(cache);
1012
1013 if (get_cache_mode(cache) >= CM_READ_ONLY)
1014 return;
1015
1016 if (dm_cache_metadata_set_needs_check(cache->cmd)) {
1017 DMERR("%s: failed to set 'needs_check' flag in metadata", dev_name);
1018 set_cache_mode(cache, CM_FAIL);
1019 }
1020
1021 DMERR_LIMIT("%s: aborting current metadata transaction", dev_name);
1022 if (dm_cache_metadata_abort(cache->cmd)) {
1023 DMERR("%s: failed to abort metadata transaction", dev_name);
1024 set_cache_mode(cache, CM_FAIL);
1025 }
1026}
1027
1028static void metadata_operation_failed(struct cache *cache, const char *op, int r)
1029{
1030 DMERR_LIMIT("%s: metadata operation '%s' failed: error = %d",
1031 cache_device_name(cache), op, r);
1032 abort_transaction(cache);
1033 set_cache_mode(cache, CM_READ_ONLY);
1034}
1035
1036/*----------------------------------------------------------------*/
1037
1038static void load_stats(struct cache *cache)
1039{
1040 struct dm_cache_statistics stats;
1041
1042 dm_cache_metadata_get_stats(cache->cmd, &stats);
1043 atomic_set(&cache->stats.read_hit, stats.read_hits);
1044 atomic_set(&cache->stats.read_miss, stats.read_misses);
1045 atomic_set(&cache->stats.write_hit, stats.write_hits);
1046 atomic_set(&cache->stats.write_miss, stats.write_misses);
1047}
1048
1049static void save_stats(struct cache *cache)
1050{
1051 struct dm_cache_statistics stats;
1052
1053 if (get_cache_mode(cache) >= CM_READ_ONLY)
1054 return;
1055
1056 stats.read_hits = atomic_read(&cache->stats.read_hit);
1057 stats.read_misses = atomic_read(&cache->stats.read_miss);
1058 stats.write_hits = atomic_read(&cache->stats.write_hit);
1059 stats.write_misses = atomic_read(&cache->stats.write_miss);
1060
1061 dm_cache_metadata_set_stats(cache->cmd, &stats);
1062}
1063
1064static void update_stats(struct cache_stats *stats, enum policy_operation op)
1065{
1066 switch (op) {
1067 case POLICY_PROMOTE:
1068 atomic_inc(&stats->promotion);
1069 break;
1070
1071 case POLICY_DEMOTE:
1072 atomic_inc(&stats->demotion);
1073 break;
1074
1075 case POLICY_WRITEBACK:
1076 atomic_inc(&stats->writeback);
1077 break;
1078 }
1079}
1080
1081/*----------------------------------------------------------------
1082 * Migration processing
1083 *
1084 * Migration covers moving data from the origin device to the cache, or
1085 * vice versa.
1086 *--------------------------------------------------------------*/
1087
1088static void inc_io_migrations(struct cache *cache)
1089{
1090 atomic_inc(&cache->nr_io_migrations);
1091}
1092
1093static void dec_io_migrations(struct cache *cache)
1094{
1095 atomic_dec(&cache->nr_io_migrations);
1096}
1097
1098static bool discard_or_flush(struct bio *bio)
1099{
1100 return bio_op(bio) == REQ_OP_DISCARD || op_is_flush(bio->bi_opf);
1101}
1102
1103static void calc_discard_block_range(struct cache *cache, struct bio *bio,
1104 dm_dblock_t *b, dm_dblock_t *e)
1105{
1106 sector_t sb = bio->bi_iter.bi_sector;
1107 sector_t se = bio_end_sector(bio);
1108
1109 *b = to_dblock(dm_sector_div_up(sb, cache->discard_block_size));
1110
1111 if (se - sb < cache->discard_block_size)
1112 *e = *b;
1113 else
1114 *e = to_dblock(block_div(se, cache->discard_block_size));
1115}
1116
1117/*----------------------------------------------------------------*/
1118
1119static void prevent_background_work(struct cache *cache)
1120{
1121 lockdep_off();
1122 down_write(&cache->background_work_lock);
1123 lockdep_on();
1124}
1125
1126static void allow_background_work(struct cache *cache)
1127{
1128 lockdep_off();
1129 up_write(&cache->background_work_lock);
1130 lockdep_on();
1131}
1132
1133static bool background_work_begin(struct cache *cache)
1134{
1135 bool r;
1136
1137 lockdep_off();
1138 r = down_read_trylock(&cache->background_work_lock);
1139 lockdep_on();
1140
1141 return r;
1142}
1143
1144static void background_work_end(struct cache *cache)
1145{
1146 lockdep_off();
1147 up_read(&cache->background_work_lock);
1148 lockdep_on();
1149}
1150
1151/*----------------------------------------------------------------*/
1152
1153static bool bio_writes_complete_block(struct cache *cache, struct bio *bio)
1154{
1155 return (bio_data_dir(bio) == WRITE) &&
1156 (bio->bi_iter.bi_size == (cache->sectors_per_block << SECTOR_SHIFT));
1157}
1158
1159static bool optimisable_bio(struct cache *cache, struct bio *bio, dm_oblock_t block)
1160{
1161 return writeback_mode(cache) &&
1162 (is_discarded_oblock(cache, block) || bio_writes_complete_block(cache, bio));
1163}
1164
1165static void quiesce(struct dm_cache_migration *mg,
1166 void (*continuation)(struct work_struct *))
1167{
1168 init_continuation(&mg->k, continuation);
1169 dm_cell_quiesce_v2(mg->cache->prison, mg->cell, &mg->k.ws);
1170}
1171
1172static struct dm_cache_migration *ws_to_mg(struct work_struct *ws)
1173{
1174 struct continuation *k = container_of(ws, struct continuation, ws);
1175 return container_of(k, struct dm_cache_migration, k);
1176}
1177
1178static void copy_complete(int read_err, unsigned long write_err, void *context)
1179{
1180 struct dm_cache_migration *mg = container_of(context, struct dm_cache_migration, k);
1181
1182 if (read_err || write_err)
1183 mg->k.input = BLK_STS_IOERR;
1184
1185 queue_continuation(mg->cache->wq, &mg->k);
1186}
1187
1188static int copy(struct dm_cache_migration *mg, bool promote)
1189{
1190 int r;
1191 struct dm_io_region o_region, c_region;
1192 struct cache *cache = mg->cache;
1193
1194 o_region.bdev = cache->origin_dev->bdev;
1195 o_region.sector = from_oblock(mg->op->oblock) * cache->sectors_per_block;
1196 o_region.count = cache->sectors_per_block;
1197
1198 c_region.bdev = cache->cache_dev->bdev;
1199 c_region.sector = from_cblock(mg->op->cblock) * cache->sectors_per_block;
1200 c_region.count = cache->sectors_per_block;
1201
1202 if (promote)
1203 r = dm_kcopyd_copy(cache->copier, &o_region, 1, &c_region, 0, copy_complete, &mg->k);
1204 else
1205 r = dm_kcopyd_copy(cache->copier, &c_region, 1, &o_region, 0, copy_complete, &mg->k);
1206
1207 return r;
1208}
1209
1210static void bio_drop_shared_lock(struct cache *cache, struct bio *bio)
1211{
1212 struct per_bio_data *pb = get_per_bio_data(bio);
1213
1214 if (pb->cell && dm_cell_put_v2(cache->prison, pb->cell))
1215 free_prison_cell(cache, pb->cell);
1216 pb->cell = NULL;
1217}
1218
1219static void overwrite_endio(struct bio *bio)
1220{
1221 struct dm_cache_migration *mg = bio->bi_private;
1222 struct cache *cache = mg->cache;
1223 struct per_bio_data *pb = get_per_bio_data(bio);
1224
1225 dm_unhook_bio(&pb->hook_info, bio);
1226
1227 if (bio->bi_status)
1228 mg->k.input = bio->bi_status;
1229
1230 queue_continuation(cache->wq, &mg->k);
1231}
1232
1233static void overwrite(struct dm_cache_migration *mg,
1234 void (*continuation)(struct work_struct *))
1235{
1236 struct bio *bio = mg->overwrite_bio;
1237 struct per_bio_data *pb = get_per_bio_data(bio);
1238
1239 dm_hook_bio(&pb->hook_info, bio, overwrite_endio, mg);
1240
1241 /*
1242 * The overwrite bio is part of the copy operation, as such it does
1243 * not set/clear discard or dirty flags.
1244 */
1245 if (mg->op->op == POLICY_PROMOTE)
1246 remap_to_cache(mg->cache, bio, mg->op->cblock);
1247 else
1248 remap_to_origin(mg->cache, bio);
1249
1250 init_continuation(&mg->k, continuation);
1251 accounted_request(mg->cache, bio);
1252}
1253
1254/*
1255 * Migration steps:
1256 *
1257 * 1) exclusive lock preventing WRITEs
1258 * 2) quiesce
1259 * 3) copy or issue overwrite bio
1260 * 4) upgrade to exclusive lock preventing READs and WRITEs
1261 * 5) quiesce
1262 * 6) update metadata and commit
1263 * 7) unlock
1264 */
1265static void mg_complete(struct dm_cache_migration *mg, bool success)
1266{
1267 struct bio_list bios;
1268 struct cache *cache = mg->cache;
1269 struct policy_work *op = mg->op;
1270 dm_cblock_t cblock = op->cblock;
1271
1272 if (success)
1273 update_stats(&cache->stats, op->op);
1274
1275 switch (op->op) {
1276 case POLICY_PROMOTE:
1277 clear_discard(cache, oblock_to_dblock(cache, op->oblock));
1278 policy_complete_background_work(cache->policy, op, success);
1279
1280 if (mg->overwrite_bio) {
1281 if (success)
1282 force_set_dirty(cache, cblock);
1283 else if (mg->k.input)
1284 mg->overwrite_bio->bi_status = mg->k.input;
1285 else
1286 mg->overwrite_bio->bi_status = BLK_STS_IOERR;
1287 bio_endio(mg->overwrite_bio);
1288 } else {
1289 if (success)
1290 force_clear_dirty(cache, cblock);
1291 dec_io_migrations(cache);
1292 }
1293 break;
1294
1295 case POLICY_DEMOTE:
1296 /*
1297 * We clear dirty here to update the nr_dirty counter.
1298 */
1299 if (success)
1300 force_clear_dirty(cache, cblock);
1301 policy_complete_background_work(cache->policy, op, success);
1302 dec_io_migrations(cache);
1303 break;
1304
1305 case POLICY_WRITEBACK:
1306 if (success)
1307 force_clear_dirty(cache, cblock);
1308 policy_complete_background_work(cache->policy, op, success);
1309 dec_io_migrations(cache);
1310 break;
1311 }
1312
1313 bio_list_init(&bios);
1314 if (mg->cell) {
1315 if (dm_cell_unlock_v2(cache->prison, mg->cell, &bios))
1316 free_prison_cell(cache, mg->cell);
1317 }
1318
1319 free_migration(mg);
1320 defer_bios(cache, &bios);
1321 wake_migration_worker(cache);
1322
1323 background_work_end(cache);
1324}
1325
1326static void mg_success(struct work_struct *ws)
1327{
1328 struct dm_cache_migration *mg = ws_to_mg(ws);
1329 mg_complete(mg, mg->k.input == 0);
1330}
1331
1332static void mg_update_metadata(struct work_struct *ws)
1333{
1334 int r;
1335 struct dm_cache_migration *mg = ws_to_mg(ws);
1336 struct cache *cache = mg->cache;
1337 struct policy_work *op = mg->op;
1338
1339 switch (op->op) {
1340 case POLICY_PROMOTE:
1341 r = dm_cache_insert_mapping(cache->cmd, op->cblock, op->oblock);
1342 if (r) {
1343 DMERR_LIMIT("%s: migration failed; couldn't insert mapping",
1344 cache_device_name(cache));
1345 metadata_operation_failed(cache, "dm_cache_insert_mapping", r);
1346
1347 mg_complete(mg, false);
1348 return;
1349 }
1350 mg_complete(mg, true);
1351 break;
1352
1353 case POLICY_DEMOTE:
1354 r = dm_cache_remove_mapping(cache->cmd, op->cblock);
1355 if (r) {
1356 DMERR_LIMIT("%s: migration failed; couldn't update on disk metadata",
1357 cache_device_name(cache));
1358 metadata_operation_failed(cache, "dm_cache_remove_mapping", r);
1359
1360 mg_complete(mg, false);
1361 return;
1362 }
1363
1364 /*
1365 * It would be nice if we only had to commit when a REQ_FLUSH
1366 * comes through. But there's one scenario that we have to
1367 * look out for:
1368 *
1369 * - vblock x in a cache block
1370 * - domotion occurs
1371 * - cache block gets reallocated and over written
1372 * - crash
1373 *
1374 * When we recover, because there was no commit the cache will
1375 * rollback to having the data for vblock x in the cache block.
1376 * But the cache block has since been overwritten, so it'll end
1377 * up pointing to data that was never in 'x' during the history
1378 * of the device.
1379 *
1380 * To avoid this issue we require a commit as part of the
1381 * demotion operation.
1382 */
1383 init_continuation(&mg->k, mg_success);
1384 continue_after_commit(&cache->committer, &mg->k);
1385 schedule_commit(&cache->committer);
1386 break;
1387
1388 case POLICY_WRITEBACK:
1389 mg_complete(mg, true);
1390 break;
1391 }
1392}
1393
1394static void mg_update_metadata_after_copy(struct work_struct *ws)
1395{
1396 struct dm_cache_migration *mg = ws_to_mg(ws);
1397
1398 /*
1399 * Did the copy succeed?
1400 */
1401 if (mg->k.input)
1402 mg_complete(mg, false);
1403 else
1404 mg_update_metadata(ws);
1405}
1406
1407static void mg_upgrade_lock(struct work_struct *ws)
1408{
1409 int r;
1410 struct dm_cache_migration *mg = ws_to_mg(ws);
1411
1412 /*
1413 * Did the copy succeed?
1414 */
1415 if (mg->k.input)
1416 mg_complete(mg, false);
1417
1418 else {
1419 /*
1420 * Now we want the lock to prevent both reads and writes.
1421 */
1422 r = dm_cell_lock_promote_v2(mg->cache->prison, mg->cell,
1423 READ_WRITE_LOCK_LEVEL);
1424 if (r < 0)
1425 mg_complete(mg, false);
1426
1427 else if (r)
1428 quiesce(mg, mg_update_metadata);
1429
1430 else
1431 mg_update_metadata(ws);
1432 }
1433}
1434
1435static void mg_full_copy(struct work_struct *ws)
1436{
1437 struct dm_cache_migration *mg = ws_to_mg(ws);
1438 struct cache *cache = mg->cache;
1439 struct policy_work *op = mg->op;
1440 bool is_policy_promote = (op->op == POLICY_PROMOTE);
1441
1442 if ((!is_policy_promote && !is_dirty(cache, op->cblock)) ||
1443 is_discarded_oblock(cache, op->oblock)) {
1444 mg_upgrade_lock(ws);
1445 return;
1446 }
1447
1448 init_continuation(&mg->k, mg_upgrade_lock);
1449
1450 if (copy(mg, is_policy_promote)) {
1451 DMERR_LIMIT("%s: migration copy failed", cache_device_name(cache));
1452 mg->k.input = BLK_STS_IOERR;
1453 mg_complete(mg, false);
1454 }
1455}
1456
1457static void mg_copy(struct work_struct *ws)
1458{
1459 struct dm_cache_migration *mg = ws_to_mg(ws);
1460
1461 if (mg->overwrite_bio) {
1462 /*
1463 * No exclusive lock was held when we last checked if the bio
1464 * was optimisable. So we have to check again in case things
1465 * have changed (eg, the block may no longer be discarded).
1466 */
1467 if (!optimisable_bio(mg->cache, mg->overwrite_bio, mg->op->oblock)) {
1468 /*
1469 * Fallback to a real full copy after doing some tidying up.
1470 */
1471 bool rb = bio_detain_shared(mg->cache, mg->op->oblock, mg->overwrite_bio);
1472 BUG_ON(rb); /* An exclussive lock must _not_ be held for this block */
1473 mg->overwrite_bio = NULL;
1474 inc_io_migrations(mg->cache);
1475 mg_full_copy(ws);
1476 return;
1477 }
1478
1479 /*
1480 * It's safe to do this here, even though it's new data
1481 * because all IO has been locked out of the block.
1482 *
1483 * mg_lock_writes() already took READ_WRITE_LOCK_LEVEL
1484 * so _not_ using mg_upgrade_lock() as continutation.
1485 */
1486 overwrite(mg, mg_update_metadata_after_copy);
1487
1488 } else
1489 mg_full_copy(ws);
1490}
1491
1492static int mg_lock_writes(struct dm_cache_migration *mg)
1493{
1494 int r;
1495 struct dm_cell_key_v2 key;
1496 struct cache *cache = mg->cache;
1497 struct dm_bio_prison_cell_v2 *prealloc;
1498
1499 prealloc = alloc_prison_cell(cache);
1500 if (!prealloc) {
1501 DMERR_LIMIT("%s: alloc_prison_cell failed", cache_device_name(cache));
1502 mg_complete(mg, false);
1503 return -ENOMEM;
1504 }
1505
1506 /*
1507 * Prevent writes to the block, but allow reads to continue.
1508 * Unless we're using an overwrite bio, in which case we lock
1509 * everything.
1510 */
1511 build_key(mg->op->oblock, oblock_succ(mg->op->oblock), &key);
1512 r = dm_cell_lock_v2(cache->prison, &key,
1513 mg->overwrite_bio ? READ_WRITE_LOCK_LEVEL : WRITE_LOCK_LEVEL,
1514 prealloc, &mg->cell);
1515 if (r < 0) {
1516 free_prison_cell(cache, prealloc);
1517 mg_complete(mg, false);
1518 return r;
1519 }
1520
1521 if (mg->cell != prealloc)
1522 free_prison_cell(cache, prealloc);
1523
1524 if (r == 0)
1525 mg_copy(&mg->k.ws);
1526 else
1527 quiesce(mg, mg_copy);
1528
1529 return 0;
1530}
1531
1532static int mg_start(struct cache *cache, struct policy_work *op, struct bio *bio)
1533{
1534 struct dm_cache_migration *mg;
1535
1536 if (!background_work_begin(cache)) {
1537 policy_complete_background_work(cache->policy, op, false);
1538 return -EPERM;
1539 }
1540
1541 mg = alloc_migration(cache);
1542 if (!mg) {
1543 policy_complete_background_work(cache->policy, op, false);
1544 background_work_end(cache);
1545 return -ENOMEM;
1546 }
1547
1548 mg->op = op;
1549 mg->overwrite_bio = bio;
1550
1551 if (!bio)
1552 inc_io_migrations(cache);
1553
1554 return mg_lock_writes(mg);
1555}
1556
1557/*----------------------------------------------------------------
1558 * invalidation processing
1559 *--------------------------------------------------------------*/
1560
1561static void invalidate_complete(struct dm_cache_migration *mg, bool success)
1562{
1563 struct bio_list bios;
1564 struct cache *cache = mg->cache;
1565
1566 bio_list_init(&bios);
1567 if (dm_cell_unlock_v2(cache->prison, mg->cell, &bios))
1568 free_prison_cell(cache, mg->cell);
1569
1570 if (!success && mg->overwrite_bio)
1571 bio_io_error(mg->overwrite_bio);
1572
1573 free_migration(mg);
1574 defer_bios(cache, &bios);
1575
1576 background_work_end(cache);
1577}
1578
1579static void invalidate_completed(struct work_struct *ws)
1580{
1581 struct dm_cache_migration *mg = ws_to_mg(ws);
1582 invalidate_complete(mg, !mg->k.input);
1583}
1584
1585static int invalidate_cblock(struct cache *cache, dm_cblock_t cblock)
1586{
1587 int r = policy_invalidate_mapping(cache->policy, cblock);
1588 if (!r) {
1589 r = dm_cache_remove_mapping(cache->cmd, cblock);
1590 if (r) {
1591 DMERR_LIMIT("%s: invalidation failed; couldn't update on disk metadata",
1592 cache_device_name(cache));
1593 metadata_operation_failed(cache, "dm_cache_remove_mapping", r);
1594 }
1595
1596 } else if (r == -ENODATA) {
1597 /*
1598 * Harmless, already unmapped.
1599 */
1600 r = 0;
1601
1602 } else
1603 DMERR("%s: policy_invalidate_mapping failed", cache_device_name(cache));
1604
1605 return r;
1606}
1607
1608static void invalidate_remove(struct work_struct *ws)
1609{
1610 int r;
1611 struct dm_cache_migration *mg = ws_to_mg(ws);
1612 struct cache *cache = mg->cache;
1613
1614 r = invalidate_cblock(cache, mg->invalidate_cblock);
1615 if (r) {
1616 invalidate_complete(mg, false);
1617 return;
1618 }
1619
1620 init_continuation(&mg->k, invalidate_completed);
1621 continue_after_commit(&cache->committer, &mg->k);
1622 remap_to_origin_clear_discard(cache, mg->overwrite_bio, mg->invalidate_oblock);
1623 mg->overwrite_bio = NULL;
1624 schedule_commit(&cache->committer);
1625}
1626
1627static int invalidate_lock(struct dm_cache_migration *mg)
1628{
1629 int r;
1630 struct dm_cell_key_v2 key;
1631 struct cache *cache = mg->cache;
1632 struct dm_bio_prison_cell_v2 *prealloc;
1633
1634 prealloc = alloc_prison_cell(cache);
1635 if (!prealloc) {
1636 invalidate_complete(mg, false);
1637 return -ENOMEM;
1638 }
1639
1640 build_key(mg->invalidate_oblock, oblock_succ(mg->invalidate_oblock), &key);
1641 r = dm_cell_lock_v2(cache->prison, &key,
1642 READ_WRITE_LOCK_LEVEL, prealloc, &mg->cell);
1643 if (r < 0) {
1644 free_prison_cell(cache, prealloc);
1645 invalidate_complete(mg, false);
1646 return r;
1647 }
1648
1649 if (mg->cell != prealloc)
1650 free_prison_cell(cache, prealloc);
1651
1652 if (r)
1653 quiesce(mg, invalidate_remove);
1654
1655 else {
1656 /*
1657 * We can't call invalidate_remove() directly here because we
1658 * might still be in request context.
1659 */
1660 init_continuation(&mg->k, invalidate_remove);
1661 queue_work(cache->wq, &mg->k.ws);
1662 }
1663
1664 return 0;
1665}
1666
1667static int invalidate_start(struct cache *cache, dm_cblock_t cblock,
1668 dm_oblock_t oblock, struct bio *bio)
1669{
1670 struct dm_cache_migration *mg;
1671
1672 if (!background_work_begin(cache))
1673 return -EPERM;
1674
1675 mg = alloc_migration(cache);
1676 if (!mg) {
1677 background_work_end(cache);
1678 return -ENOMEM;
1679 }
1680
1681 mg->overwrite_bio = bio;
1682 mg->invalidate_cblock = cblock;
1683 mg->invalidate_oblock = oblock;
1684
1685 return invalidate_lock(mg);
1686}
1687
1688/*----------------------------------------------------------------
1689 * bio processing
1690 *--------------------------------------------------------------*/
1691
1692enum busy {
1693 IDLE,
1694 BUSY
1695};
1696
1697static enum busy spare_migration_bandwidth(struct cache *cache)
1698{
1699 bool idle = iot_idle_for(&cache->tracker, HZ);
1700 sector_t current_volume = (atomic_read(&cache->nr_io_migrations) + 1) *
1701 cache->sectors_per_block;
1702
1703 if (idle && current_volume <= cache->migration_threshold)
1704 return IDLE;
1705 else
1706 return BUSY;
1707}
1708
1709static void inc_hit_counter(struct cache *cache, struct bio *bio)
1710{
1711 atomic_inc(bio_data_dir(bio) == READ ?
1712 &cache->stats.read_hit : &cache->stats.write_hit);
1713}
1714
1715static void inc_miss_counter(struct cache *cache, struct bio *bio)
1716{
1717 atomic_inc(bio_data_dir(bio) == READ ?
1718 &cache->stats.read_miss : &cache->stats.write_miss);
1719}
1720
1721/*----------------------------------------------------------------*/
1722
1723static int map_bio(struct cache *cache, struct bio *bio, dm_oblock_t block,
1724 bool *commit_needed)
1725{
1726 int r, data_dir;
1727 bool rb, background_queued;
1728 dm_cblock_t cblock;
1729
1730 *commit_needed = false;
1731
1732 rb = bio_detain_shared(cache, block, bio);
1733 if (!rb) {
1734 /*
1735 * An exclusive lock is held for this block, so we have to
1736 * wait. We set the commit_needed flag so the current
1737 * transaction will be committed asap, allowing this lock
1738 * to be dropped.
1739 */
1740 *commit_needed = true;
1741 return DM_MAPIO_SUBMITTED;
1742 }
1743
1744 data_dir = bio_data_dir(bio);
1745
1746 if (optimisable_bio(cache, bio, block)) {
1747 struct policy_work *op = NULL;
1748
1749 r = policy_lookup_with_work(cache->policy, block, &cblock, data_dir, true, &op);
1750 if (unlikely(r && r != -ENOENT)) {
1751 DMERR_LIMIT("%s: policy_lookup_with_work() failed with r = %d",
1752 cache_device_name(cache), r);
1753 bio_io_error(bio);
1754 return DM_MAPIO_SUBMITTED;
1755 }
1756
1757 if (r == -ENOENT && op) {
1758 bio_drop_shared_lock(cache, bio);
1759 BUG_ON(op->op != POLICY_PROMOTE);
1760 mg_start(cache, op, bio);
1761 return DM_MAPIO_SUBMITTED;
1762 }
1763 } else {
1764 r = policy_lookup(cache->policy, block, &cblock, data_dir, false, &background_queued);
1765 if (unlikely(r && r != -ENOENT)) {
1766 DMERR_LIMIT("%s: policy_lookup() failed with r = %d",
1767 cache_device_name(cache), r);
1768 bio_io_error(bio);
1769 return DM_MAPIO_SUBMITTED;
1770 }
1771
1772 if (background_queued)
1773 wake_migration_worker(cache);
1774 }
1775
1776 if (r == -ENOENT) {
1777 struct per_bio_data *pb = get_per_bio_data(bio);
1778
1779 /*
1780 * Miss.
1781 */
1782 inc_miss_counter(cache, bio);
1783 if (pb->req_nr == 0) {
1784 accounted_begin(cache, bio);
1785 remap_to_origin_clear_discard(cache, bio, block);
1786 } else {
1787 /*
1788 * This is a duplicate writethrough io that is no
1789 * longer needed because the block has been demoted.
1790 */
1791 bio_endio(bio);
1792 return DM_MAPIO_SUBMITTED;
1793 }
1794 } else {
1795 /*
1796 * Hit.
1797 */
1798 inc_hit_counter(cache, bio);
1799
1800 /*
1801 * Passthrough always maps to the origin, invalidating any
1802 * cache blocks that are written to.
1803 */
1804 if (passthrough_mode(cache)) {
1805 if (bio_data_dir(bio) == WRITE) {
1806 bio_drop_shared_lock(cache, bio);
1807 atomic_inc(&cache->stats.demotion);
1808 invalidate_start(cache, cblock, block, bio);
1809 } else
1810 remap_to_origin_clear_discard(cache, bio, block);
1811 } else {
1812 if (bio_data_dir(bio) == WRITE && writethrough_mode(cache) &&
1813 !is_dirty(cache, cblock)) {
1814 remap_to_origin_and_cache(cache, bio, block, cblock);
1815 accounted_begin(cache, bio);
1816 } else
1817 remap_to_cache_dirty(cache, bio, block, cblock);
1818 }
1819 }
1820
1821 /*
1822 * dm core turns FUA requests into a separate payload and FLUSH req.
1823 */
1824 if (bio->bi_opf & REQ_FUA) {
1825 /*
1826 * issue_after_commit will call accounted_begin a second time. So
1827 * we call accounted_complete() to avoid double accounting.
1828 */
1829 accounted_complete(cache, bio);
1830 issue_after_commit(&cache->committer, bio);
1831 *commit_needed = true;
1832 return DM_MAPIO_SUBMITTED;
1833 }
1834
1835 return DM_MAPIO_REMAPPED;
1836}
1837
1838static bool process_bio(struct cache *cache, struct bio *bio)
1839{
1840 bool commit_needed;
1841
1842 if (map_bio(cache, bio, get_bio_block(cache, bio), &commit_needed) == DM_MAPIO_REMAPPED)
1843 generic_make_request(bio);
1844
1845 return commit_needed;
1846}
1847
1848/*
1849 * A non-zero return indicates read_only or fail_io mode.
1850 */
1851static int commit(struct cache *cache, bool clean_shutdown)
1852{
1853 int r;
1854
1855 if (get_cache_mode(cache) >= CM_READ_ONLY)
1856 return -EINVAL;
1857
1858 atomic_inc(&cache->stats.commit_count);
1859 r = dm_cache_commit(cache->cmd, clean_shutdown);
1860 if (r)
1861 metadata_operation_failed(cache, "dm_cache_commit", r);
1862
1863 return r;
1864}
1865
1866/*
1867 * Used by the batcher.
1868 */
1869static blk_status_t commit_op(void *context)
1870{
1871 struct cache *cache = context;
1872
1873 if (dm_cache_changed_this_transaction(cache->cmd))
1874 return errno_to_blk_status(commit(cache, false));
1875
1876 return 0;
1877}
1878
1879/*----------------------------------------------------------------*/
1880
1881static bool process_flush_bio(struct cache *cache, struct bio *bio)
1882{
1883 struct per_bio_data *pb = get_per_bio_data(bio);
1884
1885 if (!pb->req_nr)
1886 remap_to_origin(cache, bio);
1887 else
1888 remap_to_cache(cache, bio, 0);
1889
1890 issue_after_commit(&cache->committer, bio);
1891 return true;
1892}
1893
1894static bool process_discard_bio(struct cache *cache, struct bio *bio)
1895{
1896 dm_dblock_t b, e;
1897
1898 // FIXME: do we need to lock the region? Or can we just assume the
1899 // user wont be so foolish as to issue discard concurrently with
1900 // other IO?
1901 calc_discard_block_range(cache, bio, &b, &e);
1902 while (b != e) {
1903 set_discard(cache, b);
1904 b = to_dblock(from_dblock(b) + 1);
1905 }
1906
1907 bio_endio(bio);
1908
1909 return false;
1910}
1911
1912static void process_deferred_bios(struct work_struct *ws)
1913{
1914 struct cache *cache = container_of(ws, struct cache, deferred_bio_worker);
1915
1916 unsigned long flags;
1917 bool commit_needed = false;
1918 struct bio_list bios;
1919 struct bio *bio;
1920
1921 bio_list_init(&bios);
1922
1923 spin_lock_irqsave(&cache->lock, flags);
1924 bio_list_merge(&bios, &cache->deferred_bios);
1925 bio_list_init(&cache->deferred_bios);
1926 spin_unlock_irqrestore(&cache->lock, flags);
1927
1928 while ((bio = bio_list_pop(&bios))) {
1929 if (bio->bi_opf & REQ_PREFLUSH)
1930 commit_needed = process_flush_bio(cache, bio) || commit_needed;
1931
1932 else if (bio_op(bio) == REQ_OP_DISCARD)
1933 commit_needed = process_discard_bio(cache, bio) || commit_needed;
1934
1935 else
1936 commit_needed = process_bio(cache, bio) || commit_needed;
1937 }
1938
1939 if (commit_needed)
1940 schedule_commit(&cache->committer);
1941}
1942
1943/*----------------------------------------------------------------
1944 * Main worker loop
1945 *--------------------------------------------------------------*/
1946
1947static void requeue_deferred_bios(struct cache *cache)
1948{
1949 struct bio *bio;
1950 struct bio_list bios;
1951
1952 bio_list_init(&bios);
1953 bio_list_merge(&bios, &cache->deferred_bios);
1954 bio_list_init(&cache->deferred_bios);
1955
1956 while ((bio = bio_list_pop(&bios))) {
1957 bio->bi_status = BLK_STS_DM_REQUEUE;
1958 bio_endio(bio);
1959 }
1960}
1961
1962/*
1963 * We want to commit periodically so that not too much
1964 * unwritten metadata builds up.
1965 */
1966static void do_waker(struct work_struct *ws)
1967{
1968 struct cache *cache = container_of(to_delayed_work(ws), struct cache, waker);
1969
1970 policy_tick(cache->policy, true);
1971 wake_migration_worker(cache);
1972 schedule_commit(&cache->committer);
1973 queue_delayed_work(cache->wq, &cache->waker, COMMIT_PERIOD);
1974}
1975
1976static void check_migrations(struct work_struct *ws)
1977{
1978 int r;
1979 struct policy_work *op;
1980 struct cache *cache = container_of(ws, struct cache, migration_worker);
1981 enum busy b;
1982
1983 for (;;) {
1984 b = spare_migration_bandwidth(cache);
1985
1986 r = policy_get_background_work(cache->policy, b == IDLE, &op);
1987 if (r == -ENODATA)
1988 break;
1989
1990 if (r) {
1991 DMERR_LIMIT("%s: policy_background_work failed",
1992 cache_device_name(cache));
1993 break;
1994 }
1995
1996 r = mg_start(cache, op, NULL);
1997 if (r)
1998 break;
1999 }
2000}
2001
2002/*----------------------------------------------------------------
2003 * Target methods
2004 *--------------------------------------------------------------*/
2005
2006/*
2007 * This function gets called on the error paths of the constructor, so we
2008 * have to cope with a partially initialised struct.
2009 */
2010static void destroy(struct cache *cache)
2011{
2012 unsigned i;
2013
2014 mempool_destroy(cache->migration_pool);
2015
2016 if (cache->prison)
2017 dm_bio_prison_destroy_v2(cache->prison);
2018
2019 if (cache->wq)
2020 destroy_workqueue(cache->wq);
2021
2022 if (cache->dirty_bitset)
2023 free_bitset(cache->dirty_bitset);
2024
2025 if (cache->discard_bitset)
2026 free_bitset(cache->discard_bitset);
2027
2028 if (cache->copier)
2029 dm_kcopyd_client_destroy(cache->copier);
2030
2031 if (cache->cmd)
2032 dm_cache_metadata_close(cache->cmd);
2033
2034 if (cache->metadata_dev)
2035 dm_put_device(cache->ti, cache->metadata_dev);
2036
2037 if (cache->origin_dev)
2038 dm_put_device(cache->ti, cache->origin_dev);
2039
2040 if (cache->cache_dev)
2041 dm_put_device(cache->ti, cache->cache_dev);
2042
2043 if (cache->policy)
2044 dm_cache_policy_destroy(cache->policy);
2045
2046 for (i = 0; i < cache->nr_ctr_args ; i++)
2047 kfree(cache->ctr_args[i]);
2048 kfree(cache->ctr_args);
2049
2050 if (cache->bs)
2051 bioset_free(cache->bs);
2052
2053 kfree(cache);
2054}
2055
2056static void cache_dtr(struct dm_target *ti)
2057{
2058 struct cache *cache = ti->private;
2059
2060 destroy(cache);
2061}
2062
2063static sector_t get_dev_size(struct dm_dev *dev)
2064{
2065 return i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT;
2066}
2067
2068/*----------------------------------------------------------------*/
2069
2070/*
2071 * Construct a cache device mapping.
2072 *
2073 * cache <metadata dev> <cache dev> <origin dev> <block size>
2074 * <#feature args> [<feature arg>]*
2075 * <policy> <#policy args> [<policy arg>]*
2076 *
2077 * metadata dev : fast device holding the persistent metadata
2078 * cache dev : fast device holding cached data blocks
2079 * origin dev : slow device holding original data blocks
2080 * block size : cache unit size in sectors
2081 *
2082 * #feature args : number of feature arguments passed
2083 * feature args : writethrough. (The default is writeback.)
2084 *
2085 * policy : the replacement policy to use
2086 * #policy args : an even number of policy arguments corresponding
2087 * to key/value pairs passed to the policy
2088 * policy args : key/value pairs passed to the policy
2089 * E.g. 'sequential_threshold 1024'
2090 * See cache-policies.txt for details.
2091 *
2092 * Optional feature arguments are:
2093 * writethrough : write through caching that prohibits cache block
2094 * content from being different from origin block content.
2095 * Without this argument, the default behaviour is to write
2096 * back cache block contents later for performance reasons,
2097 * so they may differ from the corresponding origin blocks.
2098 */
2099struct cache_args {
2100 struct dm_target *ti;
2101
2102 struct dm_dev *metadata_dev;
2103
2104 struct dm_dev *cache_dev;
2105 sector_t cache_sectors;
2106
2107 struct dm_dev *origin_dev;
2108 sector_t origin_sectors;
2109
2110 uint32_t block_size;
2111
2112 const char *policy_name;
2113 int policy_argc;
2114 const char **policy_argv;
2115
2116 struct cache_features features;
2117};
2118
2119static void destroy_cache_args(struct cache_args *ca)
2120{
2121 if (ca->metadata_dev)
2122 dm_put_device(ca->ti, ca->metadata_dev);
2123
2124 if (ca->cache_dev)
2125 dm_put_device(ca->ti, ca->cache_dev);
2126
2127 if (ca->origin_dev)
2128 dm_put_device(ca->ti, ca->origin_dev);
2129
2130 kfree(ca);
2131}
2132
2133static bool at_least_one_arg(struct dm_arg_set *as, char **error)
2134{
2135 if (!as->argc) {
2136 *error = "Insufficient args";
2137 return false;
2138 }
2139
2140 return true;
2141}
2142
2143static int parse_metadata_dev(struct cache_args *ca, struct dm_arg_set *as,
2144 char **error)
2145{
2146 int r;
2147 sector_t metadata_dev_size;
2148 char b[BDEVNAME_SIZE];
2149
2150 if (!at_least_one_arg(as, error))
2151 return -EINVAL;
2152
2153 r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
2154 &ca->metadata_dev);
2155 if (r) {
2156 *error = "Error opening metadata device";
2157 return r;
2158 }
2159
2160 metadata_dev_size = get_dev_size(ca->metadata_dev);
2161 if (metadata_dev_size > DM_CACHE_METADATA_MAX_SECTORS_WARNING)
2162 DMWARN("Metadata device %s is larger than %u sectors: excess space will not be used.",
2163 bdevname(ca->metadata_dev->bdev, b), THIN_METADATA_MAX_SECTORS);
2164
2165 return 0;
2166}
2167
2168static int parse_cache_dev(struct cache_args *ca, struct dm_arg_set *as,
2169 char **error)
2170{
2171 int r;
2172
2173 if (!at_least_one_arg(as, error))
2174 return -EINVAL;
2175
2176 r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
2177 &ca->cache_dev);
2178 if (r) {
2179 *error = "Error opening cache device";
2180 return r;
2181 }
2182 ca->cache_sectors = get_dev_size(ca->cache_dev);
2183
2184 return 0;
2185}
2186
2187static int parse_origin_dev(struct cache_args *ca, struct dm_arg_set *as,
2188 char **error)
2189{
2190 int r;
2191
2192 if (!at_least_one_arg(as, error))
2193 return -EINVAL;
2194
2195 r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
2196 &ca->origin_dev);
2197 if (r) {
2198 *error = "Error opening origin device";
2199 return r;
2200 }
2201
2202 ca->origin_sectors = get_dev_size(ca->origin_dev);
2203 if (ca->ti->len > ca->origin_sectors) {
2204 *error = "Device size larger than cached device";
2205 return -EINVAL;
2206 }
2207
2208 return 0;
2209}
2210
2211static int parse_block_size(struct cache_args *ca, struct dm_arg_set *as,
2212 char **error)
2213{
2214 unsigned long block_size;
2215
2216 if (!at_least_one_arg(as, error))
2217 return -EINVAL;
2218
2219 if (kstrtoul(dm_shift_arg(as), 10, &block_size) || !block_size ||
2220 block_size < DATA_DEV_BLOCK_SIZE_MIN_SECTORS ||
2221 block_size > DATA_DEV_BLOCK_SIZE_MAX_SECTORS ||
2222 block_size & (DATA_DEV_BLOCK_SIZE_MIN_SECTORS - 1)) {
2223 *error = "Invalid data block size";
2224 return -EINVAL;
2225 }
2226
2227 if (block_size > ca->cache_sectors) {
2228 *error = "Data block size is larger than the cache device";
2229 return -EINVAL;
2230 }
2231
2232 ca->block_size = block_size;
2233
2234 return 0;
2235}
2236
2237static void init_features(struct cache_features *cf)
2238{
2239 cf->mode = CM_WRITE;
2240 cf->io_mode = CM_IO_WRITEBACK;
2241 cf->metadata_version = 1;
2242}
2243
2244static int parse_features(struct cache_args *ca, struct dm_arg_set *as,
2245 char **error)
2246{
2247 static const struct dm_arg _args[] = {
2248 {0, 2, "Invalid number of cache feature arguments"},
2249 };
2250
2251 int r;
2252 unsigned argc;
2253 const char *arg;
2254 struct cache_features *cf = &ca->features;
2255
2256 init_features(cf);
2257
2258 r = dm_read_arg_group(_args, as, &argc, error);
2259 if (r)
2260 return -EINVAL;
2261
2262 while (argc--) {
2263 arg = dm_shift_arg(as);
2264
2265 if (!strcasecmp(arg, "writeback"))
2266 cf->io_mode = CM_IO_WRITEBACK;
2267
2268 else if (!strcasecmp(arg, "writethrough"))
2269 cf->io_mode = CM_IO_WRITETHROUGH;
2270
2271 else if (!strcasecmp(arg, "passthrough"))
2272 cf->io_mode = CM_IO_PASSTHROUGH;
2273
2274 else if (!strcasecmp(arg, "metadata2"))
2275 cf->metadata_version = 2;
2276
2277 else {
2278 *error = "Unrecognised cache feature requested";
2279 return -EINVAL;
2280 }
2281 }
2282
2283 return 0;
2284}
2285
2286static int parse_policy(struct cache_args *ca, struct dm_arg_set *as,
2287 char **error)
2288{
2289 static const struct dm_arg _args[] = {
2290 {0, 1024, "Invalid number of policy arguments"},
2291 };
2292
2293 int r;
2294
2295 if (!at_least_one_arg(as, error))
2296 return -EINVAL;
2297
2298 ca->policy_name = dm_shift_arg(as);
2299
2300 r = dm_read_arg_group(_args, as, &ca->policy_argc, error);
2301 if (r)
2302 return -EINVAL;
2303
2304 ca->policy_argv = (const char **)as->argv;
2305 dm_consume_args(as, ca->policy_argc);
2306
2307 return 0;
2308}
2309
2310static int parse_cache_args(struct cache_args *ca, int argc, char **argv,
2311 char **error)
2312{
2313 int r;
2314 struct dm_arg_set as;
2315
2316 as.argc = argc;
2317 as.argv = argv;
2318
2319 r = parse_metadata_dev(ca, &as, error);
2320 if (r)
2321 return r;
2322
2323 r = parse_cache_dev(ca, &as, error);
2324 if (r)
2325 return r;
2326
2327 r = parse_origin_dev(ca, &as, error);
2328 if (r)
2329 return r;
2330
2331 r = parse_block_size(ca, &as, error);
2332 if (r)
2333 return r;
2334
2335 r = parse_features(ca, &as, error);
2336 if (r)
2337 return r;
2338
2339 r = parse_policy(ca, &as, error);
2340 if (r)
2341 return r;
2342
2343 return 0;
2344}
2345
2346/*----------------------------------------------------------------*/
2347
2348static struct kmem_cache *migration_cache;
2349
2350#define NOT_CORE_OPTION 1
2351
2352static int process_config_option(struct cache *cache, const char *key, const char *value)
2353{
2354 unsigned long tmp;
2355
2356 if (!strcasecmp(key, "migration_threshold")) {
2357 if (kstrtoul(value, 10, &tmp))
2358 return -EINVAL;
2359
2360 cache->migration_threshold = tmp;
2361 return 0;
2362 }
2363
2364 return NOT_CORE_OPTION;
2365}
2366
2367static int set_config_value(struct cache *cache, const char *key, const char *value)
2368{
2369 int r = process_config_option(cache, key, value);
2370
2371 if (r == NOT_CORE_OPTION)
2372 r = policy_set_config_value(cache->policy, key, value);
2373
2374 if (r)
2375 DMWARN("bad config value for %s: %s", key, value);
2376
2377 return r;
2378}
2379
2380static int set_config_values(struct cache *cache, int argc, const char **argv)
2381{
2382 int r = 0;
2383
2384 if (argc & 1) {
2385 DMWARN("Odd number of policy arguments given but they should be <key> <value> pairs.");
2386 return -EINVAL;
2387 }
2388
2389 while (argc) {
2390 r = set_config_value(cache, argv[0], argv[1]);
2391 if (r)
2392 break;
2393
2394 argc -= 2;
2395 argv += 2;
2396 }
2397
2398 return r;
2399}
2400
2401static int create_cache_policy(struct cache *cache, struct cache_args *ca,
2402 char **error)
2403{
2404 struct dm_cache_policy *p = dm_cache_policy_create(ca->policy_name,
2405 cache->cache_size,
2406 cache->origin_sectors,
2407 cache->sectors_per_block);
2408 if (IS_ERR(p)) {
2409 *error = "Error creating cache's policy";
2410 return PTR_ERR(p);
2411 }
2412 cache->policy = p;
2413 BUG_ON(!cache->policy);
2414
2415 return 0;
2416}
2417
2418/*
2419 * We want the discard block size to be at least the size of the cache
2420 * block size and have no more than 2^14 discard blocks across the origin.
2421 */
2422#define MAX_DISCARD_BLOCKS (1 << 14)
2423
2424static bool too_many_discard_blocks(sector_t discard_block_size,
2425 sector_t origin_size)
2426{
2427 (void) sector_div(origin_size, discard_block_size);
2428
2429 return origin_size > MAX_DISCARD_BLOCKS;
2430}
2431
2432static sector_t calculate_discard_block_size(sector_t cache_block_size,
2433 sector_t origin_size)
2434{
2435 sector_t discard_block_size = cache_block_size;
2436
2437 if (origin_size)
2438 while (too_many_discard_blocks(discard_block_size, origin_size))
2439 discard_block_size *= 2;
2440
2441 return discard_block_size;
2442}
2443
2444static void set_cache_size(struct cache *cache, dm_cblock_t size)
2445{
2446 dm_block_t nr_blocks = from_cblock(size);
2447
2448 if (nr_blocks > (1 << 20) && cache->cache_size != size)
2449 DMWARN_LIMIT("You have created a cache device with a lot of individual cache blocks (%llu)\n"
2450 "All these mappings can consume a lot of kernel memory, and take some time to read/write.\n"
2451 "Please consider increasing the cache block size to reduce the overall cache block count.",
2452 (unsigned long long) nr_blocks);
2453
2454 cache->cache_size = size;
2455}
2456
2457static int is_congested(struct dm_dev *dev, int bdi_bits)
2458{
2459 struct request_queue *q = bdev_get_queue(dev->bdev);
2460 return bdi_congested(q->backing_dev_info, bdi_bits);
2461}
2462
2463static int cache_is_congested(struct dm_target_callbacks *cb, int bdi_bits)
2464{
2465 struct cache *cache = container_of(cb, struct cache, callbacks);
2466
2467 return is_congested(cache->origin_dev, bdi_bits) ||
2468 is_congested(cache->cache_dev, bdi_bits);
2469}
2470
2471#define DEFAULT_MIGRATION_THRESHOLD 2048
2472
2473static int cache_create(struct cache_args *ca, struct cache **result)
2474{
2475 int r = 0;
2476 char **error = &ca->ti->error;
2477 struct cache *cache;
2478 struct dm_target *ti = ca->ti;
2479 dm_block_t origin_blocks;
2480 struct dm_cache_metadata *cmd;
2481 bool may_format = ca->features.mode == CM_WRITE;
2482
2483 cache = kzalloc(sizeof(*cache), GFP_KERNEL);
2484 if (!cache)
2485 return -ENOMEM;
2486
2487 cache->ti = ca->ti;
2488 ti->private = cache;
2489 ti->num_flush_bios = 2;
2490 ti->flush_supported = true;
2491
2492 ti->num_discard_bios = 1;
2493 ti->discards_supported = true;
2494 ti->split_discard_bios = false;
2495
2496 ti->per_io_data_size = sizeof(struct per_bio_data);
2497
2498 cache->features = ca->features;
2499 if (writethrough_mode(cache)) {
2500 /* Create bioset for writethrough bios issued to origin */
2501 cache->bs = bioset_create(BIO_POOL_SIZE, 0, 0);
2502 if (!cache->bs)
2503 goto bad;
2504 }
2505
2506 cache->callbacks.congested_fn = cache_is_congested;
2507 dm_table_add_target_callbacks(ti->table, &cache->callbacks);
2508
2509 cache->metadata_dev = ca->metadata_dev;
2510 cache->origin_dev = ca->origin_dev;
2511 cache->cache_dev = ca->cache_dev;
2512
2513 ca->metadata_dev = ca->origin_dev = ca->cache_dev = NULL;
2514
2515 origin_blocks = cache->origin_sectors = ca->origin_sectors;
2516 origin_blocks = block_div(origin_blocks, ca->block_size);
2517 cache->origin_blocks = to_oblock(origin_blocks);
2518
2519 cache->sectors_per_block = ca->block_size;
2520 if (dm_set_target_max_io_len(ti, cache->sectors_per_block)) {
2521 r = -EINVAL;
2522 goto bad;
2523 }
2524
2525 if (ca->block_size & (ca->block_size - 1)) {
2526 dm_block_t cache_size = ca->cache_sectors;
2527
2528 cache->sectors_per_block_shift = -1;
2529 cache_size = block_div(cache_size, ca->block_size);
2530 set_cache_size(cache, to_cblock(cache_size));
2531 } else {
2532 cache->sectors_per_block_shift = __ffs(ca->block_size);
2533 set_cache_size(cache, to_cblock(ca->cache_sectors >> cache->sectors_per_block_shift));
2534 }
2535
2536 r = create_cache_policy(cache, ca, error);
2537 if (r)
2538 goto bad;
2539
2540 cache->policy_nr_args = ca->policy_argc;
2541 cache->migration_threshold = DEFAULT_MIGRATION_THRESHOLD;
2542
2543 r = set_config_values(cache, ca->policy_argc, ca->policy_argv);
2544 if (r) {
2545 *error = "Error setting cache policy's config values";
2546 goto bad;
2547 }
2548
2549 cmd = dm_cache_metadata_open(cache->metadata_dev->bdev,
2550 ca->block_size, may_format,
2551 dm_cache_policy_get_hint_size(cache->policy),
2552 ca->features.metadata_version);
2553 if (IS_ERR(cmd)) {
2554 *error = "Error creating metadata object";
2555 r = PTR_ERR(cmd);
2556 goto bad;
2557 }
2558 cache->cmd = cmd;
2559 set_cache_mode(cache, CM_WRITE);
2560 if (get_cache_mode(cache) != CM_WRITE) {
2561 *error = "Unable to get write access to metadata, please check/repair metadata.";
2562 r = -EINVAL;
2563 goto bad;
2564 }
2565
2566 if (passthrough_mode(cache)) {
2567 bool all_clean;
2568
2569 r = dm_cache_metadata_all_clean(cache->cmd, &all_clean);
2570 if (r) {
2571 *error = "dm_cache_metadata_all_clean() failed";
2572 goto bad;
2573 }
2574
2575 if (!all_clean) {
2576 *error = "Cannot enter passthrough mode unless all blocks are clean";
2577 r = -EINVAL;
2578 goto bad;
2579 }
2580
2581 policy_allow_migrations(cache->policy, false);
2582 }
2583
2584 spin_lock_init(&cache->lock);
2585 bio_list_init(&cache->deferred_bios);
2586 atomic_set(&cache->nr_allocated_migrations, 0);
2587 atomic_set(&cache->nr_io_migrations, 0);
2588 init_waitqueue_head(&cache->migration_wait);
2589
2590 r = -ENOMEM;
2591 atomic_set(&cache->nr_dirty, 0);
2592 cache->dirty_bitset = alloc_bitset(from_cblock(cache->cache_size));
2593 if (!cache->dirty_bitset) {
2594 *error = "could not allocate dirty bitset";
2595 goto bad;
2596 }
2597 clear_bitset(cache->dirty_bitset, from_cblock(cache->cache_size));
2598
2599 cache->discard_block_size =
2600 calculate_discard_block_size(cache->sectors_per_block,
2601 cache->origin_sectors);
2602 cache->discard_nr_blocks = to_dblock(dm_sector_div_up(cache->origin_sectors,
2603 cache->discard_block_size));
2604 cache->discard_bitset = alloc_bitset(from_dblock(cache->discard_nr_blocks));
2605 if (!cache->discard_bitset) {
2606 *error = "could not allocate discard bitset";
2607 goto bad;
2608 }
2609 clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks));
2610
2611 cache->copier = dm_kcopyd_client_create(&dm_kcopyd_throttle);
2612 if (IS_ERR(cache->copier)) {
2613 *error = "could not create kcopyd client";
2614 r = PTR_ERR(cache->copier);
2615 goto bad;
2616 }
2617
2618 cache->wq = alloc_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM, 0);
2619 if (!cache->wq) {
2620 *error = "could not create workqueue for metadata object";
2621 goto bad;
2622 }
2623 INIT_WORK(&cache->deferred_bio_worker, process_deferred_bios);
2624 INIT_WORK(&cache->migration_worker, check_migrations);
2625 INIT_DELAYED_WORK(&cache->waker, do_waker);
2626
2627 cache->prison = dm_bio_prison_create_v2(cache->wq);
2628 if (!cache->prison) {
2629 *error = "could not create bio prison";
2630 goto bad;
2631 }
2632
2633 cache->migration_pool = mempool_create_slab_pool(MIGRATION_POOL_SIZE,
2634 migration_cache);
2635 if (!cache->migration_pool) {
2636 *error = "Error creating cache's migration mempool";
2637 goto bad;
2638 }
2639
2640 cache->need_tick_bio = true;
2641 cache->sized = false;
2642 cache->invalidate = false;
2643 cache->commit_requested = false;
2644 cache->loaded_mappings = false;
2645 cache->loaded_discards = false;
2646
2647 load_stats(cache);
2648
2649 atomic_set(&cache->stats.demotion, 0);
2650 atomic_set(&cache->stats.promotion, 0);
2651 atomic_set(&cache->stats.copies_avoided, 0);
2652 atomic_set(&cache->stats.cache_cell_clash, 0);
2653 atomic_set(&cache->stats.commit_count, 0);
2654 atomic_set(&cache->stats.discard_count, 0);
2655
2656 spin_lock_init(&cache->invalidation_lock);
2657 INIT_LIST_HEAD(&cache->invalidation_requests);
2658
2659 batcher_init(&cache->committer, commit_op, cache,
2660 issue_op, cache, cache->wq);
2661 iot_init(&cache->tracker);
2662
2663 init_rwsem(&cache->background_work_lock);
2664 prevent_background_work(cache);
2665
2666 *result = cache;
2667 return 0;
2668bad:
2669 destroy(cache);
2670 return r;
2671}
2672
2673static int copy_ctr_args(struct cache *cache, int argc, const char **argv)
2674{
2675 unsigned i;
2676 const char **copy;
2677
2678 copy = kcalloc(argc, sizeof(*copy), GFP_KERNEL);
2679 if (!copy)
2680 return -ENOMEM;
2681 for (i = 0; i < argc; i++) {
2682 copy[i] = kstrdup(argv[i], GFP_KERNEL);
2683 if (!copy[i]) {
2684 while (i--)
2685 kfree(copy[i]);
2686 kfree(copy);
2687 return -ENOMEM;
2688 }
2689 }
2690
2691 cache->nr_ctr_args = argc;
2692 cache->ctr_args = copy;
2693
2694 return 0;
2695}
2696
2697static int cache_ctr(struct dm_target *ti, unsigned argc, char **argv)
2698{
2699 int r = -EINVAL;
2700 struct cache_args *ca;
2701 struct cache *cache = NULL;
2702
2703 ca = kzalloc(sizeof(*ca), GFP_KERNEL);
2704 if (!ca) {
2705 ti->error = "Error allocating memory for cache";
2706 return -ENOMEM;
2707 }
2708 ca->ti = ti;
2709
2710 r = parse_cache_args(ca, argc, argv, &ti->error);
2711 if (r)
2712 goto out;
2713
2714 r = cache_create(ca, &cache);
2715 if (r)
2716 goto out;
2717
2718 r = copy_ctr_args(cache, argc - 3, (const char **)argv + 3);
2719 if (r) {
2720 destroy(cache);
2721 goto out;
2722 }
2723
2724 ti->private = cache;
2725out:
2726 destroy_cache_args(ca);
2727 return r;
2728}
2729
2730/*----------------------------------------------------------------*/
2731
2732static int cache_map(struct dm_target *ti, struct bio *bio)
2733{
2734 struct cache *cache = ti->private;
2735
2736 int r;
2737 bool commit_needed;
2738 dm_oblock_t block = get_bio_block(cache, bio);
2739
2740 init_per_bio_data(bio);
2741 if (unlikely(from_oblock(block) >= from_oblock(cache->origin_blocks))) {
2742 /*
2743 * This can only occur if the io goes to a partial block at
2744 * the end of the origin device. We don't cache these.
2745 * Just remap to the origin and carry on.
2746 */
2747 remap_to_origin(cache, bio);
2748 accounted_begin(cache, bio);
2749 return DM_MAPIO_REMAPPED;
2750 }
2751
2752 if (discard_or_flush(bio)) {
2753 defer_bio(cache, bio);
2754 return DM_MAPIO_SUBMITTED;
2755 }
2756
2757 r = map_bio(cache, bio, block, &commit_needed);
2758 if (commit_needed)
2759 schedule_commit(&cache->committer);
2760
2761 return r;
2762}
2763
2764static int cache_end_io(struct dm_target *ti, struct bio *bio, blk_status_t *error)
2765{
2766 struct cache *cache = ti->private;
2767 unsigned long flags;
2768 struct per_bio_data *pb = get_per_bio_data(bio);
2769
2770 if (pb->tick) {
2771 policy_tick(cache->policy, false);
2772
2773 spin_lock_irqsave(&cache->lock, flags);
2774 cache->need_tick_bio = true;
2775 spin_unlock_irqrestore(&cache->lock, flags);
2776 }
2777
2778 bio_drop_shared_lock(cache, bio);
2779 accounted_complete(cache, bio);
2780
2781 return DM_ENDIO_DONE;
2782}
2783
2784static int write_dirty_bitset(struct cache *cache)
2785{
2786 int r;
2787
2788 if (get_cache_mode(cache) >= CM_READ_ONLY)
2789 return -EINVAL;
2790
2791 r = dm_cache_set_dirty_bits(cache->cmd, from_cblock(cache->cache_size), cache->dirty_bitset);
2792 if (r)
2793 metadata_operation_failed(cache, "dm_cache_set_dirty_bits", r);
2794
2795 return r;
2796}
2797
2798static int write_discard_bitset(struct cache *cache)
2799{
2800 unsigned i, r;
2801
2802 if (get_cache_mode(cache) >= CM_READ_ONLY)
2803 return -EINVAL;
2804
2805 r = dm_cache_discard_bitset_resize(cache->cmd, cache->discard_block_size,
2806 cache->discard_nr_blocks);
2807 if (r) {
2808 DMERR("%s: could not resize on-disk discard bitset", cache_device_name(cache));
2809 metadata_operation_failed(cache, "dm_cache_discard_bitset_resize", r);
2810 return r;
2811 }
2812
2813 for (i = 0; i < from_dblock(cache->discard_nr_blocks); i++) {
2814 r = dm_cache_set_discard(cache->cmd, to_dblock(i),
2815 is_discarded(cache, to_dblock(i)));
2816 if (r) {
2817 metadata_operation_failed(cache, "dm_cache_set_discard", r);
2818 return r;
2819 }
2820 }
2821
2822 return 0;
2823}
2824
2825static int write_hints(struct cache *cache)
2826{
2827 int r;
2828
2829 if (get_cache_mode(cache) >= CM_READ_ONLY)
2830 return -EINVAL;
2831
2832 r = dm_cache_write_hints(cache->cmd, cache->policy);
2833 if (r) {
2834 metadata_operation_failed(cache, "dm_cache_write_hints", r);
2835 return r;
2836 }
2837
2838 return 0;
2839}
2840
2841/*
2842 * returns true on success
2843 */
2844static bool sync_metadata(struct cache *cache)
2845{
2846 int r1, r2, r3, r4;
2847
2848 r1 = write_dirty_bitset(cache);
2849 if (r1)
2850 DMERR("%s: could not write dirty bitset", cache_device_name(cache));
2851
2852 r2 = write_discard_bitset(cache);
2853 if (r2)
2854 DMERR("%s: could not write discard bitset", cache_device_name(cache));
2855
2856 save_stats(cache);
2857
2858 r3 = write_hints(cache);
2859 if (r3)
2860 DMERR("%s: could not write hints", cache_device_name(cache));
2861
2862 /*
2863 * If writing the above metadata failed, we still commit, but don't
2864 * set the clean shutdown flag. This will effectively force every
2865 * dirty bit to be set on reload.
2866 */
2867 r4 = commit(cache, !r1 && !r2 && !r3);
2868 if (r4)
2869 DMERR("%s: could not write cache metadata", cache_device_name(cache));
2870
2871 return !r1 && !r2 && !r3 && !r4;
2872}
2873
2874static void cache_postsuspend(struct dm_target *ti)
2875{
2876 struct cache *cache = ti->private;
2877
2878 prevent_background_work(cache);
2879 BUG_ON(atomic_read(&cache->nr_io_migrations));
2880
2881 cancel_delayed_work(&cache->waker);
2882 flush_workqueue(cache->wq);
2883 WARN_ON(cache->tracker.in_flight);
2884
2885 /*
2886 * If it's a flush suspend there won't be any deferred bios, so this
2887 * call is harmless.
2888 */
2889 requeue_deferred_bios(cache);
2890
2891 if (get_cache_mode(cache) == CM_WRITE)
2892 (void) sync_metadata(cache);
2893}
2894
2895static int load_mapping(void *context, dm_oblock_t oblock, dm_cblock_t cblock,
2896 bool dirty, uint32_t hint, bool hint_valid)
2897{
2898 int r;
2899 struct cache *cache = context;
2900
2901 if (dirty) {
2902 set_bit(from_cblock(cblock), cache->dirty_bitset);
2903 atomic_inc(&cache->nr_dirty);
2904 } else
2905 clear_bit(from_cblock(cblock), cache->dirty_bitset);
2906
2907 r = policy_load_mapping(cache->policy, oblock, cblock, dirty, hint, hint_valid);
2908 if (r)
2909 return r;
2910
2911 return 0;
2912}
2913
2914/*
2915 * The discard block size in the on disk metadata is not
2916 * neccessarily the same as we're currently using. So we have to
2917 * be careful to only set the discarded attribute if we know it
2918 * covers a complete block of the new size.
2919 */
2920struct discard_load_info {
2921 struct cache *cache;
2922
2923 /*
2924 * These blocks are sized using the on disk dblock size, rather
2925 * than the current one.
2926 */
2927 dm_block_t block_size;
2928 dm_block_t discard_begin, discard_end;
2929};
2930
2931static void discard_load_info_init(struct cache *cache,
2932 struct discard_load_info *li)
2933{
2934 li->cache = cache;
2935 li->discard_begin = li->discard_end = 0;
2936}
2937
2938static void set_discard_range(struct discard_load_info *li)
2939{
2940 sector_t b, e;
2941
2942 if (li->discard_begin == li->discard_end)
2943 return;
2944
2945 /*
2946 * Convert to sectors.
2947 */
2948 b = li->discard_begin * li->block_size;
2949 e = li->discard_end * li->block_size;
2950
2951 /*
2952 * Then convert back to the current dblock size.
2953 */
2954 b = dm_sector_div_up(b, li->cache->discard_block_size);
2955 sector_div(e, li->cache->discard_block_size);
2956
2957 /*
2958 * The origin may have shrunk, so we need to check we're still in
2959 * bounds.
2960 */
2961 if (e > from_dblock(li->cache->discard_nr_blocks))
2962 e = from_dblock(li->cache->discard_nr_blocks);
2963
2964 for (; b < e; b++)
2965 set_discard(li->cache, to_dblock(b));
2966}
2967
2968static int load_discard(void *context, sector_t discard_block_size,
2969 dm_dblock_t dblock, bool discard)
2970{
2971 struct discard_load_info *li = context;
2972
2973 li->block_size = discard_block_size;
2974
2975 if (discard) {
2976 if (from_dblock(dblock) == li->discard_end)
2977 /*
2978 * We're already in a discard range, just extend it.
2979 */
2980 li->discard_end = li->discard_end + 1ULL;
2981
2982 else {
2983 /*
2984 * Emit the old range and start a new one.
2985 */
2986 set_discard_range(li);
2987 li->discard_begin = from_dblock(dblock);
2988 li->discard_end = li->discard_begin + 1ULL;
2989 }
2990 } else {
2991 set_discard_range(li);
2992 li->discard_begin = li->discard_end = 0;
2993 }
2994
2995 return 0;
2996}
2997
2998static dm_cblock_t get_cache_dev_size(struct cache *cache)
2999{
3000 sector_t size = get_dev_size(cache->cache_dev);
3001 (void) sector_div(size, cache->sectors_per_block);
3002 return to_cblock(size);
3003}
3004
3005static bool can_resize(struct cache *cache, dm_cblock_t new_size)
3006{
3007 if (from_cblock(new_size) > from_cblock(cache->cache_size))
3008 return true;
3009
3010 /*
3011 * We can't drop a dirty block when shrinking the cache.
3012 */
3013 while (from_cblock(new_size) < from_cblock(cache->cache_size)) {
3014 new_size = to_cblock(from_cblock(new_size) + 1);
3015 if (is_dirty(cache, new_size)) {
3016 DMERR("%s: unable to shrink cache; cache block %llu is dirty",
3017 cache_device_name(cache),
3018 (unsigned long long) from_cblock(new_size));
3019 return false;
3020 }
3021 }
3022
3023 return true;
3024}
3025
3026static int resize_cache_dev(struct cache *cache, dm_cblock_t new_size)
3027{
3028 int r;
3029
3030 r = dm_cache_resize(cache->cmd, new_size);
3031 if (r) {
3032 DMERR("%s: could not resize cache metadata", cache_device_name(cache));
3033 metadata_operation_failed(cache, "dm_cache_resize", r);
3034 return r;
3035 }
3036
3037 set_cache_size(cache, new_size);
3038
3039 return 0;
3040}
3041
3042static int cache_preresume(struct dm_target *ti)
3043{
3044 int r = 0;
3045 struct cache *cache = ti->private;
3046 dm_cblock_t csize = get_cache_dev_size(cache);
3047
3048 /*
3049 * Check to see if the cache has resized.
3050 */
3051 if (!cache->sized) {
3052 r = resize_cache_dev(cache, csize);
3053 if (r)
3054 return r;
3055
3056 cache->sized = true;
3057
3058 } else if (csize != cache->cache_size) {
3059 if (!can_resize(cache, csize))
3060 return -EINVAL;
3061
3062 r = resize_cache_dev(cache, csize);
3063 if (r)
3064 return r;
3065 }
3066
3067 if (!cache->loaded_mappings) {
3068 r = dm_cache_load_mappings(cache->cmd, cache->policy,
3069 load_mapping, cache);
3070 if (r) {
3071 DMERR("%s: could not load cache mappings", cache_device_name(cache));
3072 metadata_operation_failed(cache, "dm_cache_load_mappings", r);
3073 return r;
3074 }
3075
3076 cache->loaded_mappings = true;
3077 }
3078
3079 if (!cache->loaded_discards) {
3080 struct discard_load_info li;
3081
3082 /*
3083 * The discard bitset could have been resized, or the
3084 * discard block size changed. To be safe we start by
3085 * setting every dblock to not discarded.
3086 */
3087 clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks));
3088
3089 discard_load_info_init(cache, &li);
3090 r = dm_cache_load_discards(cache->cmd, load_discard, &li);
3091 if (r) {
3092 DMERR("%s: could not load origin discards", cache_device_name(cache));
3093 metadata_operation_failed(cache, "dm_cache_load_discards", r);
3094 return r;
3095 }
3096 set_discard_range(&li);
3097
3098 cache->loaded_discards = true;
3099 }
3100
3101 return r;
3102}
3103
3104static void cache_resume(struct dm_target *ti)
3105{
3106 struct cache *cache = ti->private;
3107
3108 cache->need_tick_bio = true;
3109 allow_background_work(cache);
3110 do_waker(&cache->waker.work);
3111}
3112
3113/*
3114 * Status format:
3115 *
3116 * <metadata block size> <#used metadata blocks>/<#total metadata blocks>
3117 * <cache block size> <#used cache blocks>/<#total cache blocks>
3118 * <#read hits> <#read misses> <#write hits> <#write misses>
3119 * <#demotions> <#promotions> <#dirty>
3120 * <#features> <features>*
3121 * <#core args> <core args>
3122 * <policy name> <#policy args> <policy args>* <cache metadata mode> <needs_check>
3123 */
3124static void cache_status(struct dm_target *ti, status_type_t type,
3125 unsigned status_flags, char *result, unsigned maxlen)
3126{
3127 int r = 0;
3128 unsigned i;
3129 ssize_t sz = 0;
3130 dm_block_t nr_free_blocks_metadata = 0;
3131 dm_block_t nr_blocks_metadata = 0;
3132 char buf[BDEVNAME_SIZE];
3133 struct cache *cache = ti->private;
3134 dm_cblock_t residency;
3135 bool needs_check;
3136
3137 switch (type) {
3138 case STATUSTYPE_INFO:
3139 if (get_cache_mode(cache) == CM_FAIL) {
3140 DMEMIT("Fail");
3141 break;
3142 }
3143
3144 /* Commit to ensure statistics aren't out-of-date */
3145 if (!(status_flags & DM_STATUS_NOFLUSH_FLAG) && !dm_suspended(ti))
3146 (void) commit(cache, false);
3147
3148 r = dm_cache_get_free_metadata_block_count(cache->cmd, &nr_free_blocks_metadata);
3149 if (r) {
3150 DMERR("%s: dm_cache_get_free_metadata_block_count returned %d",
3151 cache_device_name(cache), r);
3152 goto err;
3153 }
3154
3155 r = dm_cache_get_metadata_dev_size(cache->cmd, &nr_blocks_metadata);
3156 if (r) {
3157 DMERR("%s: dm_cache_get_metadata_dev_size returned %d",
3158 cache_device_name(cache), r);
3159 goto err;
3160 }
3161
3162 residency = policy_residency(cache->policy);
3163
3164 DMEMIT("%u %llu/%llu %llu %llu/%llu %u %u %u %u %u %u %lu ",
3165 (unsigned)DM_CACHE_METADATA_BLOCK_SIZE,
3166 (unsigned long long)(nr_blocks_metadata - nr_free_blocks_metadata),
3167 (unsigned long long)nr_blocks_metadata,
3168 (unsigned long long)cache->sectors_per_block,
3169 (unsigned long long) from_cblock(residency),
3170 (unsigned long long) from_cblock(cache->cache_size),
3171 (unsigned) atomic_read(&cache->stats.read_hit),
3172 (unsigned) atomic_read(&cache->stats.read_miss),
3173 (unsigned) atomic_read(&cache->stats.write_hit),
3174 (unsigned) atomic_read(&cache->stats.write_miss),
3175 (unsigned) atomic_read(&cache->stats.demotion),
3176 (unsigned) atomic_read(&cache->stats.promotion),
3177 (unsigned long) atomic_read(&cache->nr_dirty));
3178
3179 if (cache->features.metadata_version == 2)
3180 DMEMIT("2 metadata2 ");
3181 else
3182 DMEMIT("1 ");
3183
3184 if (writethrough_mode(cache))
3185 DMEMIT("writethrough ");
3186
3187 else if (passthrough_mode(cache))
3188 DMEMIT("passthrough ");
3189
3190 else if (writeback_mode(cache))
3191 DMEMIT("writeback ");
3192
3193 else {
3194 DMERR("%s: internal error: unknown io mode: %d",
3195 cache_device_name(cache), (int) cache->features.io_mode);
3196 goto err;
3197 }
3198
3199 DMEMIT("2 migration_threshold %llu ", (unsigned long long) cache->migration_threshold);
3200
3201 DMEMIT("%s ", dm_cache_policy_get_name(cache->policy));
3202 if (sz < maxlen) {
3203 r = policy_emit_config_values(cache->policy, result, maxlen, &sz);
3204 if (r)
3205 DMERR("%s: policy_emit_config_values returned %d",
3206 cache_device_name(cache), r);
3207 }
3208
3209 if (get_cache_mode(cache) == CM_READ_ONLY)
3210 DMEMIT("ro ");
3211 else
3212 DMEMIT("rw ");
3213
3214 r = dm_cache_metadata_needs_check(cache->cmd, &needs_check);
3215
3216 if (r || needs_check)
3217 DMEMIT("needs_check ");
3218 else
3219 DMEMIT("- ");
3220
3221 break;
3222
3223 case STATUSTYPE_TABLE:
3224 format_dev_t(buf, cache->metadata_dev->bdev->bd_dev);
3225 DMEMIT("%s ", buf);
3226 format_dev_t(buf, cache->cache_dev->bdev->bd_dev);
3227 DMEMIT("%s ", buf);
3228 format_dev_t(buf, cache->origin_dev->bdev->bd_dev);
3229 DMEMIT("%s", buf);
3230
3231 for (i = 0; i < cache->nr_ctr_args - 1; i++)
3232 DMEMIT(" %s", cache->ctr_args[i]);
3233 if (cache->nr_ctr_args)
3234 DMEMIT(" %s", cache->ctr_args[cache->nr_ctr_args - 1]);
3235 }
3236
3237 return;
3238
3239err:
3240 DMEMIT("Error");
3241}
3242
3243/*
3244 * Defines a range of cblocks, begin to (end - 1) are in the range. end is
3245 * the one-past-the-end value.
3246 */
3247struct cblock_range {
3248 dm_cblock_t begin;
3249 dm_cblock_t end;
3250};
3251
3252/*
3253 * A cache block range can take two forms:
3254 *
3255 * i) A single cblock, eg. '3456'
3256 * ii) A begin and end cblock with a dash between, eg. 123-234
3257 */
3258static int parse_cblock_range(struct cache *cache, const char *str,
3259 struct cblock_range *result)
3260{
3261 char dummy;
3262 uint64_t b, e;
3263 int r;
3264
3265 /*
3266 * Try and parse form (ii) first.
3267 */
3268 r = sscanf(str, "%llu-%llu%c", &b, &e, &dummy);
3269 if (r < 0)
3270 return r;
3271
3272 if (r == 2) {
3273 result->begin = to_cblock(b);
3274 result->end = to_cblock(e);
3275 return 0;
3276 }
3277
3278 /*
3279 * That didn't work, try form (i).
3280 */
3281 r = sscanf(str, "%llu%c", &b, &dummy);
3282 if (r < 0)
3283 return r;
3284
3285 if (r == 1) {
3286 result->begin = to_cblock(b);
3287 result->end = to_cblock(from_cblock(result->begin) + 1u);
3288 return 0;
3289 }
3290
3291 DMERR("%s: invalid cblock range '%s'", cache_device_name(cache), str);
3292 return -EINVAL;
3293}
3294
3295static int validate_cblock_range(struct cache *cache, struct cblock_range *range)
3296{
3297 uint64_t b = from_cblock(range->begin);
3298 uint64_t e = from_cblock(range->end);
3299 uint64_t n = from_cblock(cache->cache_size);
3300
3301 if (b >= n) {
3302 DMERR("%s: begin cblock out of range: %llu >= %llu",
3303 cache_device_name(cache), b, n);
3304 return -EINVAL;
3305 }
3306
3307 if (e > n) {
3308 DMERR("%s: end cblock out of range: %llu > %llu",
3309 cache_device_name(cache), e, n);
3310 return -EINVAL;
3311 }
3312
3313 if (b >= e) {
3314 DMERR("%s: invalid cblock range: %llu >= %llu",
3315 cache_device_name(cache), b, e);
3316 return -EINVAL;
3317 }
3318
3319 return 0;
3320}
3321
3322static inline dm_cblock_t cblock_succ(dm_cblock_t b)
3323{
3324 return to_cblock(from_cblock(b) + 1);
3325}
3326
3327static int request_invalidation(struct cache *cache, struct cblock_range *range)
3328{
3329 int r = 0;
3330
3331 /*
3332 * We don't need to do any locking here because we know we're in
3333 * passthrough mode. There's is potential for a race between an
3334 * invalidation triggered by an io and an invalidation message. This
3335 * is harmless, we must not worry if the policy call fails.
3336 */
3337 while (range->begin != range->end) {
3338 r = invalidate_cblock(cache, range->begin);
3339 if (r)
3340 return r;
3341
3342 range->begin = cblock_succ(range->begin);
3343 }
3344
3345 cache->commit_requested = true;
3346 return r;
3347}
3348
3349static int process_invalidate_cblocks_message(struct cache *cache, unsigned count,
3350 const char **cblock_ranges)
3351{
3352 int r = 0;
3353 unsigned i;
3354 struct cblock_range range;
3355
3356 if (!passthrough_mode(cache)) {
3357 DMERR("%s: cache has to be in passthrough mode for invalidation",
3358 cache_device_name(cache));
3359 return -EPERM;
3360 }
3361
3362 for (i = 0; i < count; i++) {
3363 r = parse_cblock_range(cache, cblock_ranges[i], &range);
3364 if (r)
3365 break;
3366
3367 r = validate_cblock_range(cache, &range);
3368 if (r)
3369 break;
3370
3371 /*
3372 * Pass begin and end origin blocks to the worker and wake it.
3373 */
3374 r = request_invalidation(cache, &range);
3375 if (r)
3376 break;
3377 }
3378
3379 return r;
3380}
3381
3382/*
3383 * Supports
3384 * "<key> <value>"
3385 * and
3386 * "invalidate_cblocks [(<begin>)|(<begin>-<end>)]*
3387 *
3388 * The key migration_threshold is supported by the cache target core.
3389 */
3390static int cache_message(struct dm_target *ti, unsigned argc, char **argv,
3391 char *result, unsigned maxlen)
3392{
3393 struct cache *cache = ti->private;
3394
3395 if (!argc)
3396 return -EINVAL;
3397
3398 if (get_cache_mode(cache) >= CM_READ_ONLY) {
3399 DMERR("%s: unable to service cache target messages in READ_ONLY or FAIL mode",
3400 cache_device_name(cache));
3401 return -EOPNOTSUPP;
3402 }
3403
3404 if (!strcasecmp(argv[0], "invalidate_cblocks"))
3405 return process_invalidate_cblocks_message(cache, argc - 1, (const char **) argv + 1);
3406
3407 if (argc != 2)
3408 return -EINVAL;
3409
3410 return set_config_value(cache, argv[0], argv[1]);
3411}
3412
3413static int cache_iterate_devices(struct dm_target *ti,
3414 iterate_devices_callout_fn fn, void *data)
3415{
3416 int r = 0;
3417 struct cache *cache = ti->private;
3418
3419 r = fn(ti, cache->cache_dev, 0, get_dev_size(cache->cache_dev), data);
3420 if (!r)
3421 r = fn(ti, cache->origin_dev, 0, ti->len, data);
3422
3423 return r;
3424}
3425
3426static void set_discard_limits(struct cache *cache, struct queue_limits *limits)
3427{
3428 /*
3429 * FIXME: these limits may be incompatible with the cache device
3430 */
3431 limits->max_discard_sectors = min_t(sector_t, cache->discard_block_size * 1024,
3432 cache->origin_sectors);
3433 limits->discard_granularity = cache->discard_block_size << SECTOR_SHIFT;
3434}
3435
3436static void cache_io_hints(struct dm_target *ti, struct queue_limits *limits)
3437{
3438 struct cache *cache = ti->private;
3439 uint64_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;
3440
3441 /*
3442 * If the system-determined stacked limits are compatible with the
3443 * cache's blocksize (io_opt is a factor) do not override them.
3444 */
3445 if (io_opt_sectors < cache->sectors_per_block ||
3446 do_div(io_opt_sectors, cache->sectors_per_block)) {
3447 blk_limits_io_min(limits, cache->sectors_per_block << SECTOR_SHIFT);
3448 blk_limits_io_opt(limits, cache->sectors_per_block << SECTOR_SHIFT);
3449 }
3450 set_discard_limits(cache, limits);
3451}
3452
3453/*----------------------------------------------------------------*/
3454
3455static struct target_type cache_target = {
3456 .name = "cache",
3457 .version = {2, 0, 0},
3458 .module = THIS_MODULE,
3459 .ctr = cache_ctr,
3460 .dtr = cache_dtr,
3461 .map = cache_map,
3462 .end_io = cache_end_io,
3463 .postsuspend = cache_postsuspend,
3464 .preresume = cache_preresume,
3465 .resume = cache_resume,
3466 .status = cache_status,
3467 .message = cache_message,
3468 .iterate_devices = cache_iterate_devices,
3469 .io_hints = cache_io_hints,
3470};
3471
3472static int __init dm_cache_init(void)
3473{
3474 int r;
3475
3476 migration_cache = KMEM_CACHE(dm_cache_migration, 0);
3477 if (!migration_cache) {
3478 dm_unregister_target(&cache_target);
3479 return -ENOMEM;
3480 }
3481
3482 r = dm_register_target(&cache_target);
3483 if (r) {
3484 DMERR("cache target registration failed: %d", r);
3485 return r;
3486 }
3487
3488 return 0;
3489}
3490
3491static void __exit dm_cache_exit(void)
3492{
3493 dm_unregister_target(&cache_target);
3494 kmem_cache_destroy(migration_cache);
3495}
3496
3497module_init(dm_cache_init);
3498module_exit(dm_cache_exit);
3499
3500MODULE_DESCRIPTION(DM_NAME " cache target");
3501MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
3502MODULE_LICENSE("GPL");