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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
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 bool discard_passdown:1;
357};
358
359struct cache_stats {
360 atomic_t read_hit;
361 atomic_t read_miss;
362 atomic_t write_hit;
363 atomic_t write_miss;
364 atomic_t demotion;
365 atomic_t promotion;
366 atomic_t writeback;
367 atomic_t copies_avoided;
368 atomic_t cache_cell_clash;
369 atomic_t commit_count;
370 atomic_t discard_count;
371};
372
373struct cache {
374 struct dm_target *ti;
375 spinlock_t lock;
376
377 /*
378 * Fields for converting from sectors to blocks.
379 */
380 int sectors_per_block_shift;
381 sector_t sectors_per_block;
382
383 struct dm_cache_metadata *cmd;
384
385 /*
386 * Metadata is written to this device.
387 */
388 struct dm_dev *metadata_dev;
389
390 /*
391 * The slower of the two data devices. Typically a spindle.
392 */
393 struct dm_dev *origin_dev;
394
395 /*
396 * The faster of the two data devices. Typically an SSD.
397 */
398 struct dm_dev *cache_dev;
399
400 /*
401 * Size of the origin device in _complete_ blocks and native sectors.
402 */
403 dm_oblock_t origin_blocks;
404 sector_t origin_sectors;
405
406 /*
407 * Size of the cache device in blocks.
408 */
409 dm_cblock_t cache_size;
410
411 /*
412 * Invalidation fields.
413 */
414 spinlock_t invalidation_lock;
415 struct list_head invalidation_requests;
416
417 sector_t migration_threshold;
418 wait_queue_head_t migration_wait;
419 atomic_t nr_allocated_migrations;
420
421 /*
422 * The number of in flight migrations that are performing
423 * background io. eg, promotion, writeback.
424 */
425 atomic_t nr_io_migrations;
426
427 struct bio_list deferred_bios;
428
429 struct rw_semaphore quiesce_lock;
430
431 struct dm_target_callbacks callbacks;
432
433 /*
434 * origin_blocks entries, discarded if set.
435 */
436 dm_dblock_t discard_nr_blocks;
437 unsigned long *discard_bitset;
438 uint32_t discard_block_size; /* a power of 2 times sectors per block */
439
440 /*
441 * Rather than reconstructing the table line for the status we just
442 * save it and regurgitate.
443 */
444 unsigned nr_ctr_args;
445 const char **ctr_args;
446
447 struct dm_kcopyd_client *copier;
448 struct work_struct deferred_bio_worker;
449 struct work_struct migration_worker;
450 struct workqueue_struct *wq;
451 struct delayed_work waker;
452 struct dm_bio_prison_v2 *prison;
453
454 /*
455 * cache_size entries, dirty if set
456 */
457 unsigned long *dirty_bitset;
458 atomic_t nr_dirty;
459
460 unsigned policy_nr_args;
461 struct dm_cache_policy *policy;
462
463 /*
464 * Cache features such as write-through.
465 */
466 struct cache_features features;
467
468 struct cache_stats stats;
469
470 bool need_tick_bio:1;
471 bool sized:1;
472 bool invalidate:1;
473 bool commit_requested:1;
474 bool loaded_mappings:1;
475 bool loaded_discards:1;
476
477 struct rw_semaphore background_work_lock;
478
479 struct batcher committer;
480 struct work_struct commit_ws;
481
482 struct io_tracker tracker;
483
484 mempool_t migration_pool;
485
486 struct bio_set bs;
487};
488
489struct per_bio_data {
490 bool tick:1;
491 unsigned req_nr:2;
492 struct dm_bio_prison_cell_v2 *cell;
493 struct dm_hook_info hook_info;
494 sector_t len;
495};
496
497struct dm_cache_migration {
498 struct continuation k;
499 struct cache *cache;
500
501 struct policy_work *op;
502 struct bio *overwrite_bio;
503 struct dm_bio_prison_cell_v2 *cell;
504
505 dm_cblock_t invalidate_cblock;
506 dm_oblock_t invalidate_oblock;
507};
508
509/*----------------------------------------------------------------*/
510
511static bool writethrough_mode(struct cache *cache)
512{
513 return cache->features.io_mode == CM_IO_WRITETHROUGH;
514}
515
516static bool writeback_mode(struct cache *cache)
517{
518 return cache->features.io_mode == CM_IO_WRITEBACK;
519}
520
521static inline bool passthrough_mode(struct cache *cache)
522{
523 return unlikely(cache->features.io_mode == CM_IO_PASSTHROUGH);
524}
525
526/*----------------------------------------------------------------*/
527
528static void wake_deferred_bio_worker(struct cache *cache)
529{
530 queue_work(cache->wq, &cache->deferred_bio_worker);
531}
532
533static void wake_migration_worker(struct cache *cache)
534{
535 if (passthrough_mode(cache))
536 return;
537
538 queue_work(cache->wq, &cache->migration_worker);
539}
540
541/*----------------------------------------------------------------*/
542
543static struct dm_bio_prison_cell_v2 *alloc_prison_cell(struct cache *cache)
544{
545 return dm_bio_prison_alloc_cell_v2(cache->prison, GFP_NOIO);
546}
547
548static void free_prison_cell(struct cache *cache, struct dm_bio_prison_cell_v2 *cell)
549{
550 dm_bio_prison_free_cell_v2(cache->prison, cell);
551}
552
553static struct dm_cache_migration *alloc_migration(struct cache *cache)
554{
555 struct dm_cache_migration *mg;
556
557 mg = mempool_alloc(&cache->migration_pool, GFP_NOIO);
558
559 memset(mg, 0, sizeof(*mg));
560
561 mg->cache = cache;
562 atomic_inc(&cache->nr_allocated_migrations);
563
564 return mg;
565}
566
567static void free_migration(struct dm_cache_migration *mg)
568{
569 struct cache *cache = mg->cache;
570
571 if (atomic_dec_and_test(&cache->nr_allocated_migrations))
572 wake_up(&cache->migration_wait);
573
574 mempool_free(mg, &cache->migration_pool);
575}
576
577/*----------------------------------------------------------------*/
578
579static inline dm_oblock_t oblock_succ(dm_oblock_t b)
580{
581 return to_oblock(from_oblock(b) + 1ull);
582}
583
584static void build_key(dm_oblock_t begin, dm_oblock_t end, struct dm_cell_key_v2 *key)
585{
586 key->virtual = 0;
587 key->dev = 0;
588 key->block_begin = from_oblock(begin);
589 key->block_end = from_oblock(end);
590}
591
592/*
593 * We have two lock levels. Level 0, which is used to prevent WRITEs, and
594 * level 1 which prevents *both* READs and WRITEs.
595 */
596#define WRITE_LOCK_LEVEL 0
597#define READ_WRITE_LOCK_LEVEL 1
598
599static unsigned lock_level(struct bio *bio)
600{
601 return bio_data_dir(bio) == WRITE ?
602 WRITE_LOCK_LEVEL :
603 READ_WRITE_LOCK_LEVEL;
604}
605
606/*----------------------------------------------------------------
607 * Per bio data
608 *--------------------------------------------------------------*/
609
610static struct per_bio_data *get_per_bio_data(struct bio *bio)
611{
612 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
613 BUG_ON(!pb);
614 return pb;
615}
616
617static struct per_bio_data *init_per_bio_data(struct bio *bio)
618{
619 struct per_bio_data *pb = get_per_bio_data(bio);
620
621 pb->tick = false;
622 pb->req_nr = dm_bio_get_target_bio_nr(bio);
623 pb->cell = NULL;
624 pb->len = 0;
625
626 return pb;
627}
628
629/*----------------------------------------------------------------*/
630
631static void defer_bio(struct cache *cache, struct bio *bio)
632{
633 unsigned long flags;
634
635 spin_lock_irqsave(&cache->lock, flags);
636 bio_list_add(&cache->deferred_bios, bio);
637 spin_unlock_irqrestore(&cache->lock, flags);
638
639 wake_deferred_bio_worker(cache);
640}
641
642static void defer_bios(struct cache *cache, struct bio_list *bios)
643{
644 unsigned long flags;
645
646 spin_lock_irqsave(&cache->lock, flags);
647 bio_list_merge(&cache->deferred_bios, bios);
648 bio_list_init(bios);
649 spin_unlock_irqrestore(&cache->lock, flags);
650
651 wake_deferred_bio_worker(cache);
652}
653
654/*----------------------------------------------------------------*/
655
656static bool bio_detain_shared(struct cache *cache, dm_oblock_t oblock, struct bio *bio)
657{
658 bool r;
659 struct per_bio_data *pb;
660 struct dm_cell_key_v2 key;
661 dm_oblock_t end = to_oblock(from_oblock(oblock) + 1ULL);
662 struct dm_bio_prison_cell_v2 *cell_prealloc, *cell;
663
664 cell_prealloc = alloc_prison_cell(cache); /* FIXME: allow wait if calling from worker */
665
666 build_key(oblock, end, &key);
667 r = dm_cell_get_v2(cache->prison, &key, lock_level(bio), bio, cell_prealloc, &cell);
668 if (!r) {
669 /*
670 * Failed to get the lock.
671 */
672 free_prison_cell(cache, cell_prealloc);
673 return r;
674 }
675
676 if (cell != cell_prealloc)
677 free_prison_cell(cache, cell_prealloc);
678
679 pb = get_per_bio_data(bio);
680 pb->cell = cell;
681
682 return r;
683}
684
685/*----------------------------------------------------------------*/
686
687static bool is_dirty(struct cache *cache, dm_cblock_t b)
688{
689 return test_bit(from_cblock(b), cache->dirty_bitset);
690}
691
692static void set_dirty(struct cache *cache, dm_cblock_t cblock)
693{
694 if (!test_and_set_bit(from_cblock(cblock), cache->dirty_bitset)) {
695 atomic_inc(&cache->nr_dirty);
696 policy_set_dirty(cache->policy, cblock);
697 }
698}
699
700/*
701 * These two are called when setting after migrations to force the policy
702 * and dirty bitset to be in sync.
703 */
704static void force_set_dirty(struct cache *cache, dm_cblock_t cblock)
705{
706 if (!test_and_set_bit(from_cblock(cblock), cache->dirty_bitset))
707 atomic_inc(&cache->nr_dirty);
708 policy_set_dirty(cache->policy, cblock);
709}
710
711static void force_clear_dirty(struct cache *cache, dm_cblock_t cblock)
712{
713 if (test_and_clear_bit(from_cblock(cblock), cache->dirty_bitset)) {
714 if (atomic_dec_return(&cache->nr_dirty) == 0)
715 dm_table_event(cache->ti->table);
716 }
717
718 policy_clear_dirty(cache->policy, cblock);
719}
720
721/*----------------------------------------------------------------*/
722
723static bool block_size_is_power_of_two(struct cache *cache)
724{
725 return cache->sectors_per_block_shift >= 0;
726}
727
728/* gcc on ARM generates spurious references to __udivdi3 and __umoddi3 */
729#if defined(CONFIG_ARM) && __GNUC__ == 4 && __GNUC_MINOR__ <= 6
730__always_inline
731#endif
732static dm_block_t block_div(dm_block_t b, uint32_t n)
733{
734 do_div(b, n);
735
736 return b;
737}
738
739static dm_block_t oblocks_per_dblock(struct cache *cache)
740{
741 dm_block_t oblocks = cache->discard_block_size;
742
743 if (block_size_is_power_of_two(cache))
744 oblocks >>= cache->sectors_per_block_shift;
745 else
746 oblocks = block_div(oblocks, cache->sectors_per_block);
747
748 return oblocks;
749}
750
751static dm_dblock_t oblock_to_dblock(struct cache *cache, dm_oblock_t oblock)
752{
753 return to_dblock(block_div(from_oblock(oblock),
754 oblocks_per_dblock(cache)));
755}
756
757static void set_discard(struct cache *cache, dm_dblock_t b)
758{
759 unsigned long flags;
760
761 BUG_ON(from_dblock(b) >= from_dblock(cache->discard_nr_blocks));
762 atomic_inc(&cache->stats.discard_count);
763
764 spin_lock_irqsave(&cache->lock, flags);
765 set_bit(from_dblock(b), cache->discard_bitset);
766 spin_unlock_irqrestore(&cache->lock, flags);
767}
768
769static void clear_discard(struct cache *cache, dm_dblock_t b)
770{
771 unsigned long flags;
772
773 spin_lock_irqsave(&cache->lock, flags);
774 clear_bit(from_dblock(b), cache->discard_bitset);
775 spin_unlock_irqrestore(&cache->lock, flags);
776}
777
778static bool is_discarded(struct cache *cache, dm_dblock_t b)
779{
780 int r;
781 unsigned long flags;
782
783 spin_lock_irqsave(&cache->lock, flags);
784 r = test_bit(from_dblock(b), cache->discard_bitset);
785 spin_unlock_irqrestore(&cache->lock, flags);
786
787 return r;
788}
789
790static bool is_discarded_oblock(struct cache *cache, dm_oblock_t b)
791{
792 int r;
793 unsigned long flags;
794
795 spin_lock_irqsave(&cache->lock, flags);
796 r = test_bit(from_dblock(oblock_to_dblock(cache, b)),
797 cache->discard_bitset);
798 spin_unlock_irqrestore(&cache->lock, flags);
799
800 return r;
801}
802
803/*----------------------------------------------------------------
804 * Remapping
805 *--------------------------------------------------------------*/
806static void remap_to_origin(struct cache *cache, struct bio *bio)
807{
808 bio_set_dev(bio, cache->origin_dev->bdev);
809}
810
811static void remap_to_cache(struct cache *cache, struct bio *bio,
812 dm_cblock_t cblock)
813{
814 sector_t bi_sector = bio->bi_iter.bi_sector;
815 sector_t block = from_cblock(cblock);
816
817 bio_set_dev(bio, cache->cache_dev->bdev);
818 if (!block_size_is_power_of_two(cache))
819 bio->bi_iter.bi_sector =
820 (block * cache->sectors_per_block) +
821 sector_div(bi_sector, cache->sectors_per_block);
822 else
823 bio->bi_iter.bi_sector =
824 (block << cache->sectors_per_block_shift) |
825 (bi_sector & (cache->sectors_per_block - 1));
826}
827
828static void check_if_tick_bio_needed(struct cache *cache, struct bio *bio)
829{
830 unsigned long flags;
831 struct per_bio_data *pb;
832
833 spin_lock_irqsave(&cache->lock, flags);
834 if (cache->need_tick_bio && !op_is_flush(bio->bi_opf) &&
835 bio_op(bio) != REQ_OP_DISCARD) {
836 pb = get_per_bio_data(bio);
837 pb->tick = true;
838 cache->need_tick_bio = false;
839 }
840 spin_unlock_irqrestore(&cache->lock, flags);
841}
842
843static void __remap_to_origin_clear_discard(struct cache *cache, struct bio *bio,
844 dm_oblock_t oblock, bool bio_has_pbd)
845{
846 if (bio_has_pbd)
847 check_if_tick_bio_needed(cache, bio);
848 remap_to_origin(cache, bio);
849 if (bio_data_dir(bio) == WRITE)
850 clear_discard(cache, oblock_to_dblock(cache, oblock));
851}
852
853static void remap_to_origin_clear_discard(struct cache *cache, struct bio *bio,
854 dm_oblock_t oblock)
855{
856 // FIXME: check_if_tick_bio_needed() is called way too much through this interface
857 __remap_to_origin_clear_discard(cache, bio, oblock, true);
858}
859
860static void remap_to_cache_dirty(struct cache *cache, struct bio *bio,
861 dm_oblock_t oblock, dm_cblock_t cblock)
862{
863 check_if_tick_bio_needed(cache, bio);
864 remap_to_cache(cache, bio, cblock);
865 if (bio_data_dir(bio) == WRITE) {
866 set_dirty(cache, cblock);
867 clear_discard(cache, oblock_to_dblock(cache, oblock));
868 }
869}
870
871static dm_oblock_t get_bio_block(struct cache *cache, struct bio *bio)
872{
873 sector_t block_nr = bio->bi_iter.bi_sector;
874
875 if (!block_size_is_power_of_two(cache))
876 (void) sector_div(block_nr, cache->sectors_per_block);
877 else
878 block_nr >>= cache->sectors_per_block_shift;
879
880 return to_oblock(block_nr);
881}
882
883static bool accountable_bio(struct cache *cache, struct bio *bio)
884{
885 return bio_op(bio) != REQ_OP_DISCARD;
886}
887
888static void accounted_begin(struct cache *cache, struct bio *bio)
889{
890 struct per_bio_data *pb;
891
892 if (accountable_bio(cache, bio)) {
893 pb = get_per_bio_data(bio);
894 pb->len = bio_sectors(bio);
895 iot_io_begin(&cache->tracker, pb->len);
896 }
897}
898
899static void accounted_complete(struct cache *cache, struct bio *bio)
900{
901 struct per_bio_data *pb = get_per_bio_data(bio);
902
903 iot_io_end(&cache->tracker, pb->len);
904}
905
906static void accounted_request(struct cache *cache, struct bio *bio)
907{
908 accounted_begin(cache, bio);
909 generic_make_request(bio);
910}
911
912static void issue_op(struct bio *bio, void *context)
913{
914 struct cache *cache = context;
915 accounted_request(cache, bio);
916}
917
918/*
919 * When running in writethrough mode we need to send writes to clean blocks
920 * to both the cache and origin devices. Clone the bio and send them in parallel.
921 */
922static void remap_to_origin_and_cache(struct cache *cache, struct bio *bio,
923 dm_oblock_t oblock, dm_cblock_t cblock)
924{
925 struct bio *origin_bio = bio_clone_fast(bio, GFP_NOIO, &cache->bs);
926
927 BUG_ON(!origin_bio);
928
929 bio_chain(origin_bio, bio);
930 /*
931 * Passing false to __remap_to_origin_clear_discard() skips
932 * all code that might use per_bio_data (since clone doesn't have it)
933 */
934 __remap_to_origin_clear_discard(cache, origin_bio, oblock, false);
935 submit_bio(origin_bio);
936
937 remap_to_cache(cache, bio, cblock);
938}
939
940/*----------------------------------------------------------------
941 * Failure modes
942 *--------------------------------------------------------------*/
943static enum cache_metadata_mode get_cache_mode(struct cache *cache)
944{
945 return cache->features.mode;
946}
947
948static const char *cache_device_name(struct cache *cache)
949{
950 return dm_device_name(dm_table_get_md(cache->ti->table));
951}
952
953static void notify_mode_switch(struct cache *cache, enum cache_metadata_mode mode)
954{
955 const char *descs[] = {
956 "write",
957 "read-only",
958 "fail"
959 };
960
961 dm_table_event(cache->ti->table);
962 DMINFO("%s: switching cache to %s mode",
963 cache_device_name(cache), descs[(int)mode]);
964}
965
966static void set_cache_mode(struct cache *cache, enum cache_metadata_mode new_mode)
967{
968 bool needs_check;
969 enum cache_metadata_mode old_mode = get_cache_mode(cache);
970
971 if (dm_cache_metadata_needs_check(cache->cmd, &needs_check)) {
972 DMERR("%s: unable to read needs_check flag, setting failure mode.",
973 cache_device_name(cache));
974 new_mode = CM_FAIL;
975 }
976
977 if (new_mode == CM_WRITE && needs_check) {
978 DMERR("%s: unable to switch cache to write mode until repaired.",
979 cache_device_name(cache));
980 if (old_mode != new_mode)
981 new_mode = old_mode;
982 else
983 new_mode = CM_READ_ONLY;
984 }
985
986 /* Never move out of fail mode */
987 if (old_mode == CM_FAIL)
988 new_mode = CM_FAIL;
989
990 switch (new_mode) {
991 case CM_FAIL:
992 case CM_READ_ONLY:
993 dm_cache_metadata_set_read_only(cache->cmd);
994 break;
995
996 case CM_WRITE:
997 dm_cache_metadata_set_read_write(cache->cmd);
998 break;
999 }
1000
1001 cache->features.mode = new_mode;
1002
1003 if (new_mode != old_mode)
1004 notify_mode_switch(cache, new_mode);
1005}
1006
1007static void abort_transaction(struct cache *cache)
1008{
1009 const char *dev_name = cache_device_name(cache);
1010
1011 if (get_cache_mode(cache) >= CM_READ_ONLY)
1012 return;
1013
1014 if (dm_cache_metadata_set_needs_check(cache->cmd)) {
1015 DMERR("%s: failed to set 'needs_check' flag in metadata", dev_name);
1016 set_cache_mode(cache, CM_FAIL);
1017 }
1018
1019 DMERR_LIMIT("%s: aborting current metadata transaction", dev_name);
1020 if (dm_cache_metadata_abort(cache->cmd)) {
1021 DMERR("%s: failed to abort metadata transaction", dev_name);
1022 set_cache_mode(cache, CM_FAIL);
1023 }
1024}
1025
1026static void metadata_operation_failed(struct cache *cache, const char *op, int r)
1027{
1028 DMERR_LIMIT("%s: metadata operation '%s' failed: error = %d",
1029 cache_device_name(cache), op, r);
1030 abort_transaction(cache);
1031 set_cache_mode(cache, CM_READ_ONLY);
1032}
1033
1034/*----------------------------------------------------------------*/
1035
1036static void load_stats(struct cache *cache)
1037{
1038 struct dm_cache_statistics stats;
1039
1040 dm_cache_metadata_get_stats(cache->cmd, &stats);
1041 atomic_set(&cache->stats.read_hit, stats.read_hits);
1042 atomic_set(&cache->stats.read_miss, stats.read_misses);
1043 atomic_set(&cache->stats.write_hit, stats.write_hits);
1044 atomic_set(&cache->stats.write_miss, stats.write_misses);
1045}
1046
1047static void save_stats(struct cache *cache)
1048{
1049 struct dm_cache_statistics stats;
1050
1051 if (get_cache_mode(cache) >= CM_READ_ONLY)
1052 return;
1053
1054 stats.read_hits = atomic_read(&cache->stats.read_hit);
1055 stats.read_misses = atomic_read(&cache->stats.read_miss);
1056 stats.write_hits = atomic_read(&cache->stats.write_hit);
1057 stats.write_misses = atomic_read(&cache->stats.write_miss);
1058
1059 dm_cache_metadata_set_stats(cache->cmd, &stats);
1060}
1061
1062static void update_stats(struct cache_stats *stats, enum policy_operation op)
1063{
1064 switch (op) {
1065 case POLICY_PROMOTE:
1066 atomic_inc(&stats->promotion);
1067 break;
1068
1069 case POLICY_DEMOTE:
1070 atomic_inc(&stats->demotion);
1071 break;
1072
1073 case POLICY_WRITEBACK:
1074 atomic_inc(&stats->writeback);
1075 break;
1076 }
1077}
1078
1079/*----------------------------------------------------------------
1080 * Migration processing
1081 *
1082 * Migration covers moving data from the origin device to the cache, or
1083 * vice versa.
1084 *--------------------------------------------------------------*/
1085
1086static void inc_io_migrations(struct cache *cache)
1087{
1088 atomic_inc(&cache->nr_io_migrations);
1089}
1090
1091static void dec_io_migrations(struct cache *cache)
1092{
1093 atomic_dec(&cache->nr_io_migrations);
1094}
1095
1096static bool discard_or_flush(struct bio *bio)
1097{
1098 return bio_op(bio) == REQ_OP_DISCARD || op_is_flush(bio->bi_opf);
1099}
1100
1101static void calc_discard_block_range(struct cache *cache, struct bio *bio,
1102 dm_dblock_t *b, dm_dblock_t *e)
1103{
1104 sector_t sb = bio->bi_iter.bi_sector;
1105 sector_t se = bio_end_sector(bio);
1106
1107 *b = to_dblock(dm_sector_div_up(sb, cache->discard_block_size));
1108
1109 if (se - sb < cache->discard_block_size)
1110 *e = *b;
1111 else
1112 *e = to_dblock(block_div(se, cache->discard_block_size));
1113}
1114
1115/*----------------------------------------------------------------*/
1116
1117static void prevent_background_work(struct cache *cache)
1118{
1119 lockdep_off();
1120 down_write(&cache->background_work_lock);
1121 lockdep_on();
1122}
1123
1124static void allow_background_work(struct cache *cache)
1125{
1126 lockdep_off();
1127 up_write(&cache->background_work_lock);
1128 lockdep_on();
1129}
1130
1131static bool background_work_begin(struct cache *cache)
1132{
1133 bool r;
1134
1135 lockdep_off();
1136 r = down_read_trylock(&cache->background_work_lock);
1137 lockdep_on();
1138
1139 return r;
1140}
1141
1142static void background_work_end(struct cache *cache)
1143{
1144 lockdep_off();
1145 up_read(&cache->background_work_lock);
1146 lockdep_on();
1147}
1148
1149/*----------------------------------------------------------------*/
1150
1151static bool bio_writes_complete_block(struct cache *cache, struct bio *bio)
1152{
1153 return (bio_data_dir(bio) == WRITE) &&
1154 (bio->bi_iter.bi_size == (cache->sectors_per_block << SECTOR_SHIFT));
1155}
1156
1157static bool optimisable_bio(struct cache *cache, struct bio *bio, dm_oblock_t block)
1158{
1159 return writeback_mode(cache) &&
1160 (is_discarded_oblock(cache, block) || bio_writes_complete_block(cache, bio));
1161}
1162
1163static void quiesce(struct dm_cache_migration *mg,
1164 void (*continuation)(struct work_struct *))
1165{
1166 init_continuation(&mg->k, continuation);
1167 dm_cell_quiesce_v2(mg->cache->prison, mg->cell, &mg->k.ws);
1168}
1169
1170static struct dm_cache_migration *ws_to_mg(struct work_struct *ws)
1171{
1172 struct continuation *k = container_of(ws, struct continuation, ws);
1173 return container_of(k, struct dm_cache_migration, k);
1174}
1175
1176static void copy_complete(int read_err, unsigned long write_err, void *context)
1177{
1178 struct dm_cache_migration *mg = container_of(context, struct dm_cache_migration, k);
1179
1180 if (read_err || write_err)
1181 mg->k.input = BLK_STS_IOERR;
1182
1183 queue_continuation(mg->cache->wq, &mg->k);
1184}
1185
1186static void copy(struct dm_cache_migration *mg, bool promote)
1187{
1188 struct dm_io_region o_region, c_region;
1189 struct cache *cache = mg->cache;
1190
1191 o_region.bdev = cache->origin_dev->bdev;
1192 o_region.sector = from_oblock(mg->op->oblock) * cache->sectors_per_block;
1193 o_region.count = cache->sectors_per_block;
1194
1195 c_region.bdev = cache->cache_dev->bdev;
1196 c_region.sector = from_cblock(mg->op->cblock) * cache->sectors_per_block;
1197 c_region.count = cache->sectors_per_block;
1198
1199 if (promote)
1200 dm_kcopyd_copy(cache->copier, &o_region, 1, &c_region, 0, copy_complete, &mg->k);
1201 else
1202 dm_kcopyd_copy(cache->copier, &c_region, 1, &o_region, 0, copy_complete, &mg->k);
1203}
1204
1205static void bio_drop_shared_lock(struct cache *cache, struct bio *bio)
1206{
1207 struct per_bio_data *pb = get_per_bio_data(bio);
1208
1209 if (pb->cell && dm_cell_put_v2(cache->prison, pb->cell))
1210 free_prison_cell(cache, pb->cell);
1211 pb->cell = NULL;
1212}
1213
1214static void overwrite_endio(struct bio *bio)
1215{
1216 struct dm_cache_migration *mg = bio->bi_private;
1217 struct cache *cache = mg->cache;
1218 struct per_bio_data *pb = get_per_bio_data(bio);
1219
1220 dm_unhook_bio(&pb->hook_info, bio);
1221
1222 if (bio->bi_status)
1223 mg->k.input = bio->bi_status;
1224
1225 queue_continuation(cache->wq, &mg->k);
1226}
1227
1228static void overwrite(struct dm_cache_migration *mg,
1229 void (*continuation)(struct work_struct *))
1230{
1231 struct bio *bio = mg->overwrite_bio;
1232 struct per_bio_data *pb = get_per_bio_data(bio);
1233
1234 dm_hook_bio(&pb->hook_info, bio, overwrite_endio, mg);
1235
1236 /*
1237 * The overwrite bio is part of the copy operation, as such it does
1238 * not set/clear discard or dirty flags.
1239 */
1240 if (mg->op->op == POLICY_PROMOTE)
1241 remap_to_cache(mg->cache, bio, mg->op->cblock);
1242 else
1243 remap_to_origin(mg->cache, bio);
1244
1245 init_continuation(&mg->k, continuation);
1246 accounted_request(mg->cache, bio);
1247}
1248
1249/*
1250 * Migration steps:
1251 *
1252 * 1) exclusive lock preventing WRITEs
1253 * 2) quiesce
1254 * 3) copy or issue overwrite bio
1255 * 4) upgrade to exclusive lock preventing READs and WRITEs
1256 * 5) quiesce
1257 * 6) update metadata and commit
1258 * 7) unlock
1259 */
1260static void mg_complete(struct dm_cache_migration *mg, bool success)
1261{
1262 struct bio_list bios;
1263 struct cache *cache = mg->cache;
1264 struct policy_work *op = mg->op;
1265 dm_cblock_t cblock = op->cblock;
1266
1267 if (success)
1268 update_stats(&cache->stats, op->op);
1269
1270 switch (op->op) {
1271 case POLICY_PROMOTE:
1272 clear_discard(cache, oblock_to_dblock(cache, op->oblock));
1273 policy_complete_background_work(cache->policy, op, success);
1274
1275 if (mg->overwrite_bio) {
1276 if (success)
1277 force_set_dirty(cache, cblock);
1278 else if (mg->k.input)
1279 mg->overwrite_bio->bi_status = mg->k.input;
1280 else
1281 mg->overwrite_bio->bi_status = BLK_STS_IOERR;
1282 bio_endio(mg->overwrite_bio);
1283 } else {
1284 if (success)
1285 force_clear_dirty(cache, cblock);
1286 dec_io_migrations(cache);
1287 }
1288 break;
1289
1290 case POLICY_DEMOTE:
1291 /*
1292 * We clear dirty here to update the nr_dirty counter.
1293 */
1294 if (success)
1295 force_clear_dirty(cache, cblock);
1296 policy_complete_background_work(cache->policy, op, success);
1297 dec_io_migrations(cache);
1298 break;
1299
1300 case POLICY_WRITEBACK:
1301 if (success)
1302 force_clear_dirty(cache, cblock);
1303 policy_complete_background_work(cache->policy, op, success);
1304 dec_io_migrations(cache);
1305 break;
1306 }
1307
1308 bio_list_init(&bios);
1309 if (mg->cell) {
1310 if (dm_cell_unlock_v2(cache->prison, mg->cell, &bios))
1311 free_prison_cell(cache, mg->cell);
1312 }
1313
1314 free_migration(mg);
1315 defer_bios(cache, &bios);
1316 wake_migration_worker(cache);
1317
1318 background_work_end(cache);
1319}
1320
1321static void mg_success(struct work_struct *ws)
1322{
1323 struct dm_cache_migration *mg = ws_to_mg(ws);
1324 mg_complete(mg, mg->k.input == 0);
1325}
1326
1327static void mg_update_metadata(struct work_struct *ws)
1328{
1329 int r;
1330 struct dm_cache_migration *mg = ws_to_mg(ws);
1331 struct cache *cache = mg->cache;
1332 struct policy_work *op = mg->op;
1333
1334 switch (op->op) {
1335 case POLICY_PROMOTE:
1336 r = dm_cache_insert_mapping(cache->cmd, op->cblock, op->oblock);
1337 if (r) {
1338 DMERR_LIMIT("%s: migration failed; couldn't insert mapping",
1339 cache_device_name(cache));
1340 metadata_operation_failed(cache, "dm_cache_insert_mapping", r);
1341
1342 mg_complete(mg, false);
1343 return;
1344 }
1345 mg_complete(mg, true);
1346 break;
1347
1348 case POLICY_DEMOTE:
1349 r = dm_cache_remove_mapping(cache->cmd, op->cblock);
1350 if (r) {
1351 DMERR_LIMIT("%s: migration failed; couldn't update on disk metadata",
1352 cache_device_name(cache));
1353 metadata_operation_failed(cache, "dm_cache_remove_mapping", r);
1354
1355 mg_complete(mg, false);
1356 return;
1357 }
1358
1359 /*
1360 * It would be nice if we only had to commit when a REQ_FLUSH
1361 * comes through. But there's one scenario that we have to
1362 * look out for:
1363 *
1364 * - vblock x in a cache block
1365 * - domotion occurs
1366 * - cache block gets reallocated and over written
1367 * - crash
1368 *
1369 * When we recover, because there was no commit the cache will
1370 * rollback to having the data for vblock x in the cache block.
1371 * But the cache block has since been overwritten, so it'll end
1372 * up pointing to data that was never in 'x' during the history
1373 * of the device.
1374 *
1375 * To avoid this issue we require a commit as part of the
1376 * demotion operation.
1377 */
1378 init_continuation(&mg->k, mg_success);
1379 continue_after_commit(&cache->committer, &mg->k);
1380 schedule_commit(&cache->committer);
1381 break;
1382
1383 case POLICY_WRITEBACK:
1384 mg_complete(mg, true);
1385 break;
1386 }
1387}
1388
1389static void mg_update_metadata_after_copy(struct work_struct *ws)
1390{
1391 struct dm_cache_migration *mg = ws_to_mg(ws);
1392
1393 /*
1394 * Did the copy succeed?
1395 */
1396 if (mg->k.input)
1397 mg_complete(mg, false);
1398 else
1399 mg_update_metadata(ws);
1400}
1401
1402static void mg_upgrade_lock(struct work_struct *ws)
1403{
1404 int r;
1405 struct dm_cache_migration *mg = ws_to_mg(ws);
1406
1407 /*
1408 * Did the copy succeed?
1409 */
1410 if (mg->k.input)
1411 mg_complete(mg, false);
1412
1413 else {
1414 /*
1415 * Now we want the lock to prevent both reads and writes.
1416 */
1417 r = dm_cell_lock_promote_v2(mg->cache->prison, mg->cell,
1418 READ_WRITE_LOCK_LEVEL);
1419 if (r < 0)
1420 mg_complete(mg, false);
1421
1422 else if (r)
1423 quiesce(mg, mg_update_metadata);
1424
1425 else
1426 mg_update_metadata(ws);
1427 }
1428}
1429
1430static void mg_full_copy(struct work_struct *ws)
1431{
1432 struct dm_cache_migration *mg = ws_to_mg(ws);
1433 struct cache *cache = mg->cache;
1434 struct policy_work *op = mg->op;
1435 bool is_policy_promote = (op->op == POLICY_PROMOTE);
1436
1437 if ((!is_policy_promote && !is_dirty(cache, op->cblock)) ||
1438 is_discarded_oblock(cache, op->oblock)) {
1439 mg_upgrade_lock(ws);
1440 return;
1441 }
1442
1443 init_continuation(&mg->k, mg_upgrade_lock);
1444 copy(mg, is_policy_promote);
1445}
1446
1447static void mg_copy(struct work_struct *ws)
1448{
1449 struct dm_cache_migration *mg = ws_to_mg(ws);
1450
1451 if (mg->overwrite_bio) {
1452 /*
1453 * No exclusive lock was held when we last checked if the bio
1454 * was optimisable. So we have to check again in case things
1455 * have changed (eg, the block may no longer be discarded).
1456 */
1457 if (!optimisable_bio(mg->cache, mg->overwrite_bio, mg->op->oblock)) {
1458 /*
1459 * Fallback to a real full copy after doing some tidying up.
1460 */
1461 bool rb = bio_detain_shared(mg->cache, mg->op->oblock, mg->overwrite_bio);
1462 BUG_ON(rb); /* An exclussive lock must _not_ be held for this block */
1463 mg->overwrite_bio = NULL;
1464 inc_io_migrations(mg->cache);
1465 mg_full_copy(ws);
1466 return;
1467 }
1468
1469 /*
1470 * It's safe to do this here, even though it's new data
1471 * because all IO has been locked out of the block.
1472 *
1473 * mg_lock_writes() already took READ_WRITE_LOCK_LEVEL
1474 * so _not_ using mg_upgrade_lock() as continutation.
1475 */
1476 overwrite(mg, mg_update_metadata_after_copy);
1477
1478 } else
1479 mg_full_copy(ws);
1480}
1481
1482static int mg_lock_writes(struct dm_cache_migration *mg)
1483{
1484 int r;
1485 struct dm_cell_key_v2 key;
1486 struct cache *cache = mg->cache;
1487 struct dm_bio_prison_cell_v2 *prealloc;
1488
1489 prealloc = alloc_prison_cell(cache);
1490
1491 /*
1492 * Prevent writes to the block, but allow reads to continue.
1493 * Unless we're using an overwrite bio, in which case we lock
1494 * everything.
1495 */
1496 build_key(mg->op->oblock, oblock_succ(mg->op->oblock), &key);
1497 r = dm_cell_lock_v2(cache->prison, &key,
1498 mg->overwrite_bio ? READ_WRITE_LOCK_LEVEL : WRITE_LOCK_LEVEL,
1499 prealloc, &mg->cell);
1500 if (r < 0) {
1501 free_prison_cell(cache, prealloc);
1502 mg_complete(mg, false);
1503 return r;
1504 }
1505
1506 if (mg->cell != prealloc)
1507 free_prison_cell(cache, prealloc);
1508
1509 if (r == 0)
1510 mg_copy(&mg->k.ws);
1511 else
1512 quiesce(mg, mg_copy);
1513
1514 return 0;
1515}
1516
1517static int mg_start(struct cache *cache, struct policy_work *op, struct bio *bio)
1518{
1519 struct dm_cache_migration *mg;
1520
1521 if (!background_work_begin(cache)) {
1522 policy_complete_background_work(cache->policy, op, false);
1523 return -EPERM;
1524 }
1525
1526 mg = alloc_migration(cache);
1527
1528 mg->op = op;
1529 mg->overwrite_bio = bio;
1530
1531 if (!bio)
1532 inc_io_migrations(cache);
1533
1534 return mg_lock_writes(mg);
1535}
1536
1537/*----------------------------------------------------------------
1538 * invalidation processing
1539 *--------------------------------------------------------------*/
1540
1541static void invalidate_complete(struct dm_cache_migration *mg, bool success)
1542{
1543 struct bio_list bios;
1544 struct cache *cache = mg->cache;
1545
1546 bio_list_init(&bios);
1547 if (dm_cell_unlock_v2(cache->prison, mg->cell, &bios))
1548 free_prison_cell(cache, mg->cell);
1549
1550 if (!success && mg->overwrite_bio)
1551 bio_io_error(mg->overwrite_bio);
1552
1553 free_migration(mg);
1554 defer_bios(cache, &bios);
1555
1556 background_work_end(cache);
1557}
1558
1559static void invalidate_completed(struct work_struct *ws)
1560{
1561 struct dm_cache_migration *mg = ws_to_mg(ws);
1562 invalidate_complete(mg, !mg->k.input);
1563}
1564
1565static int invalidate_cblock(struct cache *cache, dm_cblock_t cblock)
1566{
1567 int r = policy_invalidate_mapping(cache->policy, cblock);
1568 if (!r) {
1569 r = dm_cache_remove_mapping(cache->cmd, cblock);
1570 if (r) {
1571 DMERR_LIMIT("%s: invalidation failed; couldn't update on disk metadata",
1572 cache_device_name(cache));
1573 metadata_operation_failed(cache, "dm_cache_remove_mapping", r);
1574 }
1575
1576 } else if (r == -ENODATA) {
1577 /*
1578 * Harmless, already unmapped.
1579 */
1580 r = 0;
1581
1582 } else
1583 DMERR("%s: policy_invalidate_mapping failed", cache_device_name(cache));
1584
1585 return r;
1586}
1587
1588static void invalidate_remove(struct work_struct *ws)
1589{
1590 int r;
1591 struct dm_cache_migration *mg = ws_to_mg(ws);
1592 struct cache *cache = mg->cache;
1593
1594 r = invalidate_cblock(cache, mg->invalidate_cblock);
1595 if (r) {
1596 invalidate_complete(mg, false);
1597 return;
1598 }
1599
1600 init_continuation(&mg->k, invalidate_completed);
1601 continue_after_commit(&cache->committer, &mg->k);
1602 remap_to_origin_clear_discard(cache, mg->overwrite_bio, mg->invalidate_oblock);
1603 mg->overwrite_bio = NULL;
1604 schedule_commit(&cache->committer);
1605}
1606
1607static int invalidate_lock(struct dm_cache_migration *mg)
1608{
1609 int r;
1610 struct dm_cell_key_v2 key;
1611 struct cache *cache = mg->cache;
1612 struct dm_bio_prison_cell_v2 *prealloc;
1613
1614 prealloc = alloc_prison_cell(cache);
1615
1616 build_key(mg->invalidate_oblock, oblock_succ(mg->invalidate_oblock), &key);
1617 r = dm_cell_lock_v2(cache->prison, &key,
1618 READ_WRITE_LOCK_LEVEL, prealloc, &mg->cell);
1619 if (r < 0) {
1620 free_prison_cell(cache, prealloc);
1621 invalidate_complete(mg, false);
1622 return r;
1623 }
1624
1625 if (mg->cell != prealloc)
1626 free_prison_cell(cache, prealloc);
1627
1628 if (r)
1629 quiesce(mg, invalidate_remove);
1630
1631 else {
1632 /*
1633 * We can't call invalidate_remove() directly here because we
1634 * might still be in request context.
1635 */
1636 init_continuation(&mg->k, invalidate_remove);
1637 queue_work(cache->wq, &mg->k.ws);
1638 }
1639
1640 return 0;
1641}
1642
1643static int invalidate_start(struct cache *cache, dm_cblock_t cblock,
1644 dm_oblock_t oblock, struct bio *bio)
1645{
1646 struct dm_cache_migration *mg;
1647
1648 if (!background_work_begin(cache))
1649 return -EPERM;
1650
1651 mg = alloc_migration(cache);
1652
1653 mg->overwrite_bio = bio;
1654 mg->invalidate_cblock = cblock;
1655 mg->invalidate_oblock = oblock;
1656
1657 return invalidate_lock(mg);
1658}
1659
1660/*----------------------------------------------------------------
1661 * bio processing
1662 *--------------------------------------------------------------*/
1663
1664enum busy {
1665 IDLE,
1666 BUSY
1667};
1668
1669static enum busy spare_migration_bandwidth(struct cache *cache)
1670{
1671 bool idle = iot_idle_for(&cache->tracker, HZ);
1672 sector_t current_volume = (atomic_read(&cache->nr_io_migrations) + 1) *
1673 cache->sectors_per_block;
1674
1675 if (idle && current_volume <= cache->migration_threshold)
1676 return IDLE;
1677 else
1678 return BUSY;
1679}
1680
1681static void inc_hit_counter(struct cache *cache, struct bio *bio)
1682{
1683 atomic_inc(bio_data_dir(bio) == READ ?
1684 &cache->stats.read_hit : &cache->stats.write_hit);
1685}
1686
1687static void inc_miss_counter(struct cache *cache, struct bio *bio)
1688{
1689 atomic_inc(bio_data_dir(bio) == READ ?
1690 &cache->stats.read_miss : &cache->stats.write_miss);
1691}
1692
1693/*----------------------------------------------------------------*/
1694
1695static int map_bio(struct cache *cache, struct bio *bio, dm_oblock_t block,
1696 bool *commit_needed)
1697{
1698 int r, data_dir;
1699 bool rb, background_queued;
1700 dm_cblock_t cblock;
1701
1702 *commit_needed = false;
1703
1704 rb = bio_detain_shared(cache, block, bio);
1705 if (!rb) {
1706 /*
1707 * An exclusive lock is held for this block, so we have to
1708 * wait. We set the commit_needed flag so the current
1709 * transaction will be committed asap, allowing this lock
1710 * to be dropped.
1711 */
1712 *commit_needed = true;
1713 return DM_MAPIO_SUBMITTED;
1714 }
1715
1716 data_dir = bio_data_dir(bio);
1717
1718 if (optimisable_bio(cache, bio, block)) {
1719 struct policy_work *op = NULL;
1720
1721 r = policy_lookup_with_work(cache->policy, block, &cblock, data_dir, true, &op);
1722 if (unlikely(r && r != -ENOENT)) {
1723 DMERR_LIMIT("%s: policy_lookup_with_work() failed with r = %d",
1724 cache_device_name(cache), r);
1725 bio_io_error(bio);
1726 return DM_MAPIO_SUBMITTED;
1727 }
1728
1729 if (r == -ENOENT && op) {
1730 bio_drop_shared_lock(cache, bio);
1731 BUG_ON(op->op != POLICY_PROMOTE);
1732 mg_start(cache, op, bio);
1733 return DM_MAPIO_SUBMITTED;
1734 }
1735 } else {
1736 r = policy_lookup(cache->policy, block, &cblock, data_dir, false, &background_queued);
1737 if (unlikely(r && r != -ENOENT)) {
1738 DMERR_LIMIT("%s: policy_lookup() failed with r = %d",
1739 cache_device_name(cache), r);
1740 bio_io_error(bio);
1741 return DM_MAPIO_SUBMITTED;
1742 }
1743
1744 if (background_queued)
1745 wake_migration_worker(cache);
1746 }
1747
1748 if (r == -ENOENT) {
1749 struct per_bio_data *pb = get_per_bio_data(bio);
1750
1751 /*
1752 * Miss.
1753 */
1754 inc_miss_counter(cache, bio);
1755 if (pb->req_nr == 0) {
1756 accounted_begin(cache, bio);
1757 remap_to_origin_clear_discard(cache, bio, block);
1758 } else {
1759 /*
1760 * This is a duplicate writethrough io that is no
1761 * longer needed because the block has been demoted.
1762 */
1763 bio_endio(bio);
1764 return DM_MAPIO_SUBMITTED;
1765 }
1766 } else {
1767 /*
1768 * Hit.
1769 */
1770 inc_hit_counter(cache, bio);
1771
1772 /*
1773 * Passthrough always maps to the origin, invalidating any
1774 * cache blocks that are written to.
1775 */
1776 if (passthrough_mode(cache)) {
1777 if (bio_data_dir(bio) == WRITE) {
1778 bio_drop_shared_lock(cache, bio);
1779 atomic_inc(&cache->stats.demotion);
1780 invalidate_start(cache, cblock, block, bio);
1781 } else
1782 remap_to_origin_clear_discard(cache, bio, block);
1783 } else {
1784 if (bio_data_dir(bio) == WRITE && writethrough_mode(cache) &&
1785 !is_dirty(cache, cblock)) {
1786 remap_to_origin_and_cache(cache, bio, block, cblock);
1787 accounted_begin(cache, bio);
1788 } else
1789 remap_to_cache_dirty(cache, bio, block, cblock);
1790 }
1791 }
1792
1793 /*
1794 * dm core turns FUA requests into a separate payload and FLUSH req.
1795 */
1796 if (bio->bi_opf & REQ_FUA) {
1797 /*
1798 * issue_after_commit will call accounted_begin a second time. So
1799 * we call accounted_complete() to avoid double accounting.
1800 */
1801 accounted_complete(cache, bio);
1802 issue_after_commit(&cache->committer, bio);
1803 *commit_needed = true;
1804 return DM_MAPIO_SUBMITTED;
1805 }
1806
1807 return DM_MAPIO_REMAPPED;
1808}
1809
1810static bool process_bio(struct cache *cache, struct bio *bio)
1811{
1812 bool commit_needed;
1813
1814 if (map_bio(cache, bio, get_bio_block(cache, bio), &commit_needed) == DM_MAPIO_REMAPPED)
1815 generic_make_request(bio);
1816
1817 return commit_needed;
1818}
1819
1820/*
1821 * A non-zero return indicates read_only or fail_io mode.
1822 */
1823static int commit(struct cache *cache, bool clean_shutdown)
1824{
1825 int r;
1826
1827 if (get_cache_mode(cache) >= CM_READ_ONLY)
1828 return -EINVAL;
1829
1830 atomic_inc(&cache->stats.commit_count);
1831 r = dm_cache_commit(cache->cmd, clean_shutdown);
1832 if (r)
1833 metadata_operation_failed(cache, "dm_cache_commit", r);
1834
1835 return r;
1836}
1837
1838/*
1839 * Used by the batcher.
1840 */
1841static blk_status_t commit_op(void *context)
1842{
1843 struct cache *cache = context;
1844
1845 if (dm_cache_changed_this_transaction(cache->cmd))
1846 return errno_to_blk_status(commit(cache, false));
1847
1848 return 0;
1849}
1850
1851/*----------------------------------------------------------------*/
1852
1853static bool process_flush_bio(struct cache *cache, struct bio *bio)
1854{
1855 struct per_bio_data *pb = get_per_bio_data(bio);
1856
1857 if (!pb->req_nr)
1858 remap_to_origin(cache, bio);
1859 else
1860 remap_to_cache(cache, bio, 0);
1861
1862 issue_after_commit(&cache->committer, bio);
1863 return true;
1864}
1865
1866static bool process_discard_bio(struct cache *cache, struct bio *bio)
1867{
1868 dm_dblock_t b, e;
1869
1870 // FIXME: do we need to lock the region? Or can we just assume the
1871 // user wont be so foolish as to issue discard concurrently with
1872 // other IO?
1873 calc_discard_block_range(cache, bio, &b, &e);
1874 while (b != e) {
1875 set_discard(cache, b);
1876 b = to_dblock(from_dblock(b) + 1);
1877 }
1878
1879 if (cache->features.discard_passdown) {
1880 remap_to_origin(cache, bio);
1881 generic_make_request(bio);
1882 } else
1883 bio_endio(bio);
1884
1885 return false;
1886}
1887
1888static void process_deferred_bios(struct work_struct *ws)
1889{
1890 struct cache *cache = container_of(ws, struct cache, deferred_bio_worker);
1891
1892 unsigned long flags;
1893 bool commit_needed = false;
1894 struct bio_list bios;
1895 struct bio *bio;
1896
1897 bio_list_init(&bios);
1898
1899 spin_lock_irqsave(&cache->lock, flags);
1900 bio_list_merge(&bios, &cache->deferred_bios);
1901 bio_list_init(&cache->deferred_bios);
1902 spin_unlock_irqrestore(&cache->lock, flags);
1903
1904 while ((bio = bio_list_pop(&bios))) {
1905 if (bio->bi_opf & REQ_PREFLUSH)
1906 commit_needed = process_flush_bio(cache, bio) || commit_needed;
1907
1908 else if (bio_op(bio) == REQ_OP_DISCARD)
1909 commit_needed = process_discard_bio(cache, bio) || commit_needed;
1910
1911 else
1912 commit_needed = process_bio(cache, bio) || commit_needed;
1913 }
1914
1915 if (commit_needed)
1916 schedule_commit(&cache->committer);
1917}
1918
1919/*----------------------------------------------------------------
1920 * Main worker loop
1921 *--------------------------------------------------------------*/
1922
1923static void requeue_deferred_bios(struct cache *cache)
1924{
1925 struct bio *bio;
1926 struct bio_list bios;
1927
1928 bio_list_init(&bios);
1929 bio_list_merge(&bios, &cache->deferred_bios);
1930 bio_list_init(&cache->deferred_bios);
1931
1932 while ((bio = bio_list_pop(&bios))) {
1933 bio->bi_status = BLK_STS_DM_REQUEUE;
1934 bio_endio(bio);
1935 }
1936}
1937
1938/*
1939 * We want to commit periodically so that not too much
1940 * unwritten metadata builds up.
1941 */
1942static void do_waker(struct work_struct *ws)
1943{
1944 struct cache *cache = container_of(to_delayed_work(ws), struct cache, waker);
1945
1946 policy_tick(cache->policy, true);
1947 wake_migration_worker(cache);
1948 schedule_commit(&cache->committer);
1949 queue_delayed_work(cache->wq, &cache->waker, COMMIT_PERIOD);
1950}
1951
1952static void check_migrations(struct work_struct *ws)
1953{
1954 int r;
1955 struct policy_work *op;
1956 struct cache *cache = container_of(ws, struct cache, migration_worker);
1957 enum busy b;
1958
1959 for (;;) {
1960 b = spare_migration_bandwidth(cache);
1961
1962 r = policy_get_background_work(cache->policy, b == IDLE, &op);
1963 if (r == -ENODATA)
1964 break;
1965
1966 if (r) {
1967 DMERR_LIMIT("%s: policy_background_work failed",
1968 cache_device_name(cache));
1969 break;
1970 }
1971
1972 r = mg_start(cache, op, NULL);
1973 if (r)
1974 break;
1975 }
1976}
1977
1978/*----------------------------------------------------------------
1979 * Target methods
1980 *--------------------------------------------------------------*/
1981
1982/*
1983 * This function gets called on the error paths of the constructor, so we
1984 * have to cope with a partially initialised struct.
1985 */
1986static void destroy(struct cache *cache)
1987{
1988 unsigned i;
1989
1990 mempool_exit(&cache->migration_pool);
1991
1992 if (cache->prison)
1993 dm_bio_prison_destroy_v2(cache->prison);
1994
1995 if (cache->wq)
1996 destroy_workqueue(cache->wq);
1997
1998 if (cache->dirty_bitset)
1999 free_bitset(cache->dirty_bitset);
2000
2001 if (cache->discard_bitset)
2002 free_bitset(cache->discard_bitset);
2003
2004 if (cache->copier)
2005 dm_kcopyd_client_destroy(cache->copier);
2006
2007 if (cache->cmd)
2008 dm_cache_metadata_close(cache->cmd);
2009
2010 if (cache->metadata_dev)
2011 dm_put_device(cache->ti, cache->metadata_dev);
2012
2013 if (cache->origin_dev)
2014 dm_put_device(cache->ti, cache->origin_dev);
2015
2016 if (cache->cache_dev)
2017 dm_put_device(cache->ti, cache->cache_dev);
2018
2019 if (cache->policy)
2020 dm_cache_policy_destroy(cache->policy);
2021
2022 for (i = 0; i < cache->nr_ctr_args ; i++)
2023 kfree(cache->ctr_args[i]);
2024 kfree(cache->ctr_args);
2025
2026 bioset_exit(&cache->bs);
2027
2028 kfree(cache);
2029}
2030
2031static void cache_dtr(struct dm_target *ti)
2032{
2033 struct cache *cache = ti->private;
2034
2035 destroy(cache);
2036}
2037
2038static sector_t get_dev_size(struct dm_dev *dev)
2039{
2040 return i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT;
2041}
2042
2043/*----------------------------------------------------------------*/
2044
2045/*
2046 * Construct a cache device mapping.
2047 *
2048 * cache <metadata dev> <cache dev> <origin dev> <block size>
2049 * <#feature args> [<feature arg>]*
2050 * <policy> <#policy args> [<policy arg>]*
2051 *
2052 * metadata dev : fast device holding the persistent metadata
2053 * cache dev : fast device holding cached data blocks
2054 * origin dev : slow device holding original data blocks
2055 * block size : cache unit size in sectors
2056 *
2057 * #feature args : number of feature arguments passed
2058 * feature args : writethrough. (The default is writeback.)
2059 *
2060 * policy : the replacement policy to use
2061 * #policy args : an even number of policy arguments corresponding
2062 * to key/value pairs passed to the policy
2063 * policy args : key/value pairs passed to the policy
2064 * E.g. 'sequential_threshold 1024'
2065 * See cache-policies.txt for details.
2066 *
2067 * Optional feature arguments are:
2068 * writethrough : write through caching that prohibits cache block
2069 * content from being different from origin block content.
2070 * Without this argument, the default behaviour is to write
2071 * back cache block contents later for performance reasons,
2072 * so they may differ from the corresponding origin blocks.
2073 */
2074struct cache_args {
2075 struct dm_target *ti;
2076
2077 struct dm_dev *metadata_dev;
2078
2079 struct dm_dev *cache_dev;
2080 sector_t cache_sectors;
2081
2082 struct dm_dev *origin_dev;
2083 sector_t origin_sectors;
2084
2085 uint32_t block_size;
2086
2087 const char *policy_name;
2088 int policy_argc;
2089 const char **policy_argv;
2090
2091 struct cache_features features;
2092};
2093
2094static void destroy_cache_args(struct cache_args *ca)
2095{
2096 if (ca->metadata_dev)
2097 dm_put_device(ca->ti, ca->metadata_dev);
2098
2099 if (ca->cache_dev)
2100 dm_put_device(ca->ti, ca->cache_dev);
2101
2102 if (ca->origin_dev)
2103 dm_put_device(ca->ti, ca->origin_dev);
2104
2105 kfree(ca);
2106}
2107
2108static bool at_least_one_arg(struct dm_arg_set *as, char **error)
2109{
2110 if (!as->argc) {
2111 *error = "Insufficient args";
2112 return false;
2113 }
2114
2115 return true;
2116}
2117
2118static int parse_metadata_dev(struct cache_args *ca, struct dm_arg_set *as,
2119 char **error)
2120{
2121 int r;
2122 sector_t metadata_dev_size;
2123 char b[BDEVNAME_SIZE];
2124
2125 if (!at_least_one_arg(as, error))
2126 return -EINVAL;
2127
2128 r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
2129 &ca->metadata_dev);
2130 if (r) {
2131 *error = "Error opening metadata device";
2132 return r;
2133 }
2134
2135 metadata_dev_size = get_dev_size(ca->metadata_dev);
2136 if (metadata_dev_size > DM_CACHE_METADATA_MAX_SECTORS_WARNING)
2137 DMWARN("Metadata device %s is larger than %u sectors: excess space will not be used.",
2138 bdevname(ca->metadata_dev->bdev, b), THIN_METADATA_MAX_SECTORS);
2139
2140 return 0;
2141}
2142
2143static int parse_cache_dev(struct cache_args *ca, struct dm_arg_set *as,
2144 char **error)
2145{
2146 int r;
2147
2148 if (!at_least_one_arg(as, error))
2149 return -EINVAL;
2150
2151 r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
2152 &ca->cache_dev);
2153 if (r) {
2154 *error = "Error opening cache device";
2155 return r;
2156 }
2157 ca->cache_sectors = get_dev_size(ca->cache_dev);
2158
2159 return 0;
2160}
2161
2162static int parse_origin_dev(struct cache_args *ca, struct dm_arg_set *as,
2163 char **error)
2164{
2165 int r;
2166
2167 if (!at_least_one_arg(as, error))
2168 return -EINVAL;
2169
2170 r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
2171 &ca->origin_dev);
2172 if (r) {
2173 *error = "Error opening origin device";
2174 return r;
2175 }
2176
2177 ca->origin_sectors = get_dev_size(ca->origin_dev);
2178 if (ca->ti->len > ca->origin_sectors) {
2179 *error = "Device size larger than cached device";
2180 return -EINVAL;
2181 }
2182
2183 return 0;
2184}
2185
2186static int parse_block_size(struct cache_args *ca, struct dm_arg_set *as,
2187 char **error)
2188{
2189 unsigned long block_size;
2190
2191 if (!at_least_one_arg(as, error))
2192 return -EINVAL;
2193
2194 if (kstrtoul(dm_shift_arg(as), 10, &block_size) || !block_size ||
2195 block_size < DATA_DEV_BLOCK_SIZE_MIN_SECTORS ||
2196 block_size > DATA_DEV_BLOCK_SIZE_MAX_SECTORS ||
2197 block_size & (DATA_DEV_BLOCK_SIZE_MIN_SECTORS - 1)) {
2198 *error = "Invalid data block size";
2199 return -EINVAL;
2200 }
2201
2202 if (block_size > ca->cache_sectors) {
2203 *error = "Data block size is larger than the cache device";
2204 return -EINVAL;
2205 }
2206
2207 ca->block_size = block_size;
2208
2209 return 0;
2210}
2211
2212static void init_features(struct cache_features *cf)
2213{
2214 cf->mode = CM_WRITE;
2215 cf->io_mode = CM_IO_WRITEBACK;
2216 cf->metadata_version = 1;
2217 cf->discard_passdown = true;
2218}
2219
2220static int parse_features(struct cache_args *ca, struct dm_arg_set *as,
2221 char **error)
2222{
2223 static const struct dm_arg _args[] = {
2224 {0, 3, "Invalid number of cache feature arguments"},
2225 };
2226
2227 int r, mode_ctr = 0;
2228 unsigned argc;
2229 const char *arg;
2230 struct cache_features *cf = &ca->features;
2231
2232 init_features(cf);
2233
2234 r = dm_read_arg_group(_args, as, &argc, error);
2235 if (r)
2236 return -EINVAL;
2237
2238 while (argc--) {
2239 arg = dm_shift_arg(as);
2240
2241 if (!strcasecmp(arg, "writeback")) {
2242 cf->io_mode = CM_IO_WRITEBACK;
2243 mode_ctr++;
2244 }
2245
2246 else if (!strcasecmp(arg, "writethrough")) {
2247 cf->io_mode = CM_IO_WRITETHROUGH;
2248 mode_ctr++;
2249 }
2250
2251 else if (!strcasecmp(arg, "passthrough")) {
2252 cf->io_mode = CM_IO_PASSTHROUGH;
2253 mode_ctr++;
2254 }
2255
2256 else if (!strcasecmp(arg, "metadata2"))
2257 cf->metadata_version = 2;
2258
2259 else if (!strcasecmp(arg, "no_discard_passdown"))
2260 cf->discard_passdown = false;
2261
2262 else {
2263 *error = "Unrecognised cache feature requested";
2264 return -EINVAL;
2265 }
2266 }
2267
2268 if (mode_ctr > 1) {
2269 *error = "Duplicate cache io_mode features requested";
2270 return -EINVAL;
2271 }
2272
2273 return 0;
2274}
2275
2276static int parse_policy(struct cache_args *ca, struct dm_arg_set *as,
2277 char **error)
2278{
2279 static const struct dm_arg _args[] = {
2280 {0, 1024, "Invalid number of policy arguments"},
2281 };
2282
2283 int r;
2284
2285 if (!at_least_one_arg(as, error))
2286 return -EINVAL;
2287
2288 ca->policy_name = dm_shift_arg(as);
2289
2290 r = dm_read_arg_group(_args, as, &ca->policy_argc, error);
2291 if (r)
2292 return -EINVAL;
2293
2294 ca->policy_argv = (const char **)as->argv;
2295 dm_consume_args(as, ca->policy_argc);
2296
2297 return 0;
2298}
2299
2300static int parse_cache_args(struct cache_args *ca, int argc, char **argv,
2301 char **error)
2302{
2303 int r;
2304 struct dm_arg_set as;
2305
2306 as.argc = argc;
2307 as.argv = argv;
2308
2309 r = parse_metadata_dev(ca, &as, error);
2310 if (r)
2311 return r;
2312
2313 r = parse_cache_dev(ca, &as, error);
2314 if (r)
2315 return r;
2316
2317 r = parse_origin_dev(ca, &as, error);
2318 if (r)
2319 return r;
2320
2321 r = parse_block_size(ca, &as, error);
2322 if (r)
2323 return r;
2324
2325 r = parse_features(ca, &as, error);
2326 if (r)
2327 return r;
2328
2329 r = parse_policy(ca, &as, error);
2330 if (r)
2331 return r;
2332
2333 return 0;
2334}
2335
2336/*----------------------------------------------------------------*/
2337
2338static struct kmem_cache *migration_cache;
2339
2340#define NOT_CORE_OPTION 1
2341
2342static int process_config_option(struct cache *cache, const char *key, const char *value)
2343{
2344 unsigned long tmp;
2345
2346 if (!strcasecmp(key, "migration_threshold")) {
2347 if (kstrtoul(value, 10, &tmp))
2348 return -EINVAL;
2349
2350 cache->migration_threshold = tmp;
2351 return 0;
2352 }
2353
2354 return NOT_CORE_OPTION;
2355}
2356
2357static int set_config_value(struct cache *cache, const char *key, const char *value)
2358{
2359 int r = process_config_option(cache, key, value);
2360
2361 if (r == NOT_CORE_OPTION)
2362 r = policy_set_config_value(cache->policy, key, value);
2363
2364 if (r)
2365 DMWARN("bad config value for %s: %s", key, value);
2366
2367 return r;
2368}
2369
2370static int set_config_values(struct cache *cache, int argc, const char **argv)
2371{
2372 int r = 0;
2373
2374 if (argc & 1) {
2375 DMWARN("Odd number of policy arguments given but they should be <key> <value> pairs.");
2376 return -EINVAL;
2377 }
2378
2379 while (argc) {
2380 r = set_config_value(cache, argv[0], argv[1]);
2381 if (r)
2382 break;
2383
2384 argc -= 2;
2385 argv += 2;
2386 }
2387
2388 return r;
2389}
2390
2391static int create_cache_policy(struct cache *cache, struct cache_args *ca,
2392 char **error)
2393{
2394 struct dm_cache_policy *p = dm_cache_policy_create(ca->policy_name,
2395 cache->cache_size,
2396 cache->origin_sectors,
2397 cache->sectors_per_block);
2398 if (IS_ERR(p)) {
2399 *error = "Error creating cache's policy";
2400 return PTR_ERR(p);
2401 }
2402 cache->policy = p;
2403 BUG_ON(!cache->policy);
2404
2405 return 0;
2406}
2407
2408/*
2409 * We want the discard block size to be at least the size of the cache
2410 * block size and have no more than 2^14 discard blocks across the origin.
2411 */
2412#define MAX_DISCARD_BLOCKS (1 << 14)
2413
2414static bool too_many_discard_blocks(sector_t discard_block_size,
2415 sector_t origin_size)
2416{
2417 (void) sector_div(origin_size, discard_block_size);
2418
2419 return origin_size > MAX_DISCARD_BLOCKS;
2420}
2421
2422static sector_t calculate_discard_block_size(sector_t cache_block_size,
2423 sector_t origin_size)
2424{
2425 sector_t discard_block_size = cache_block_size;
2426
2427 if (origin_size)
2428 while (too_many_discard_blocks(discard_block_size, origin_size))
2429 discard_block_size *= 2;
2430
2431 return discard_block_size;
2432}
2433
2434static void set_cache_size(struct cache *cache, dm_cblock_t size)
2435{
2436 dm_block_t nr_blocks = from_cblock(size);
2437
2438 if (nr_blocks > (1 << 20) && cache->cache_size != size)
2439 DMWARN_LIMIT("You have created a cache device with a lot of individual cache blocks (%llu)\n"
2440 "All these mappings can consume a lot of kernel memory, and take some time to read/write.\n"
2441 "Please consider increasing the cache block size to reduce the overall cache block count.",
2442 (unsigned long long) nr_blocks);
2443
2444 cache->cache_size = size;
2445}
2446
2447static int is_congested(struct dm_dev *dev, int bdi_bits)
2448{
2449 struct request_queue *q = bdev_get_queue(dev->bdev);
2450 return bdi_congested(q->backing_dev_info, bdi_bits);
2451}
2452
2453static int cache_is_congested(struct dm_target_callbacks *cb, int bdi_bits)
2454{
2455 struct cache *cache = container_of(cb, struct cache, callbacks);
2456
2457 return is_congested(cache->origin_dev, bdi_bits) ||
2458 is_congested(cache->cache_dev, bdi_bits);
2459}
2460
2461#define DEFAULT_MIGRATION_THRESHOLD 2048
2462
2463static int cache_create(struct cache_args *ca, struct cache **result)
2464{
2465 int r = 0;
2466 char **error = &ca->ti->error;
2467 struct cache *cache;
2468 struct dm_target *ti = ca->ti;
2469 dm_block_t origin_blocks;
2470 struct dm_cache_metadata *cmd;
2471 bool may_format = ca->features.mode == CM_WRITE;
2472
2473 cache = kzalloc(sizeof(*cache), GFP_KERNEL);
2474 if (!cache)
2475 return -ENOMEM;
2476
2477 cache->ti = ca->ti;
2478 ti->private = cache;
2479 ti->num_flush_bios = 2;
2480 ti->flush_supported = true;
2481
2482 ti->num_discard_bios = 1;
2483 ti->discards_supported = true;
2484
2485 ti->per_io_data_size = sizeof(struct per_bio_data);
2486
2487 cache->features = ca->features;
2488 if (writethrough_mode(cache)) {
2489 /* Create bioset for writethrough bios issued to origin */
2490 r = bioset_init(&cache->bs, BIO_POOL_SIZE, 0, 0);
2491 if (r)
2492 goto bad;
2493 }
2494
2495 cache->callbacks.congested_fn = cache_is_congested;
2496 dm_table_add_target_callbacks(ti->table, &cache->callbacks);
2497
2498 cache->metadata_dev = ca->metadata_dev;
2499 cache->origin_dev = ca->origin_dev;
2500 cache->cache_dev = ca->cache_dev;
2501
2502 ca->metadata_dev = ca->origin_dev = ca->cache_dev = NULL;
2503
2504 origin_blocks = cache->origin_sectors = ca->origin_sectors;
2505 origin_blocks = block_div(origin_blocks, ca->block_size);
2506 cache->origin_blocks = to_oblock(origin_blocks);
2507
2508 cache->sectors_per_block = ca->block_size;
2509 if (dm_set_target_max_io_len(ti, cache->sectors_per_block)) {
2510 r = -EINVAL;
2511 goto bad;
2512 }
2513
2514 if (ca->block_size & (ca->block_size - 1)) {
2515 dm_block_t cache_size = ca->cache_sectors;
2516
2517 cache->sectors_per_block_shift = -1;
2518 cache_size = block_div(cache_size, ca->block_size);
2519 set_cache_size(cache, to_cblock(cache_size));
2520 } else {
2521 cache->sectors_per_block_shift = __ffs(ca->block_size);
2522 set_cache_size(cache, to_cblock(ca->cache_sectors >> cache->sectors_per_block_shift));
2523 }
2524
2525 r = create_cache_policy(cache, ca, error);
2526 if (r)
2527 goto bad;
2528
2529 cache->policy_nr_args = ca->policy_argc;
2530 cache->migration_threshold = DEFAULT_MIGRATION_THRESHOLD;
2531
2532 r = set_config_values(cache, ca->policy_argc, ca->policy_argv);
2533 if (r) {
2534 *error = "Error setting cache policy's config values";
2535 goto bad;
2536 }
2537
2538 cmd = dm_cache_metadata_open(cache->metadata_dev->bdev,
2539 ca->block_size, may_format,
2540 dm_cache_policy_get_hint_size(cache->policy),
2541 ca->features.metadata_version);
2542 if (IS_ERR(cmd)) {
2543 *error = "Error creating metadata object";
2544 r = PTR_ERR(cmd);
2545 goto bad;
2546 }
2547 cache->cmd = cmd;
2548 set_cache_mode(cache, CM_WRITE);
2549 if (get_cache_mode(cache) != CM_WRITE) {
2550 *error = "Unable to get write access to metadata, please check/repair metadata.";
2551 r = -EINVAL;
2552 goto bad;
2553 }
2554
2555 if (passthrough_mode(cache)) {
2556 bool all_clean;
2557
2558 r = dm_cache_metadata_all_clean(cache->cmd, &all_clean);
2559 if (r) {
2560 *error = "dm_cache_metadata_all_clean() failed";
2561 goto bad;
2562 }
2563
2564 if (!all_clean) {
2565 *error = "Cannot enter passthrough mode unless all blocks are clean";
2566 r = -EINVAL;
2567 goto bad;
2568 }
2569
2570 policy_allow_migrations(cache->policy, false);
2571 }
2572
2573 spin_lock_init(&cache->lock);
2574 bio_list_init(&cache->deferred_bios);
2575 atomic_set(&cache->nr_allocated_migrations, 0);
2576 atomic_set(&cache->nr_io_migrations, 0);
2577 init_waitqueue_head(&cache->migration_wait);
2578
2579 r = -ENOMEM;
2580 atomic_set(&cache->nr_dirty, 0);
2581 cache->dirty_bitset = alloc_bitset(from_cblock(cache->cache_size));
2582 if (!cache->dirty_bitset) {
2583 *error = "could not allocate dirty bitset";
2584 goto bad;
2585 }
2586 clear_bitset(cache->dirty_bitset, from_cblock(cache->cache_size));
2587
2588 cache->discard_block_size =
2589 calculate_discard_block_size(cache->sectors_per_block,
2590 cache->origin_sectors);
2591 cache->discard_nr_blocks = to_dblock(dm_sector_div_up(cache->origin_sectors,
2592 cache->discard_block_size));
2593 cache->discard_bitset = alloc_bitset(from_dblock(cache->discard_nr_blocks));
2594 if (!cache->discard_bitset) {
2595 *error = "could not allocate discard bitset";
2596 goto bad;
2597 }
2598 clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks));
2599
2600 cache->copier = dm_kcopyd_client_create(&dm_kcopyd_throttle);
2601 if (IS_ERR(cache->copier)) {
2602 *error = "could not create kcopyd client";
2603 r = PTR_ERR(cache->copier);
2604 goto bad;
2605 }
2606
2607 cache->wq = alloc_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM, 0);
2608 if (!cache->wq) {
2609 *error = "could not create workqueue for metadata object";
2610 goto bad;
2611 }
2612 INIT_WORK(&cache->deferred_bio_worker, process_deferred_bios);
2613 INIT_WORK(&cache->migration_worker, check_migrations);
2614 INIT_DELAYED_WORK(&cache->waker, do_waker);
2615
2616 cache->prison = dm_bio_prison_create_v2(cache->wq);
2617 if (!cache->prison) {
2618 *error = "could not create bio prison";
2619 goto bad;
2620 }
2621
2622 r = mempool_init_slab_pool(&cache->migration_pool, MIGRATION_POOL_SIZE,
2623 migration_cache);
2624 if (r) {
2625 *error = "Error creating cache's migration mempool";
2626 goto bad;
2627 }
2628
2629 cache->need_tick_bio = true;
2630 cache->sized = false;
2631 cache->invalidate = false;
2632 cache->commit_requested = false;
2633 cache->loaded_mappings = false;
2634 cache->loaded_discards = false;
2635
2636 load_stats(cache);
2637
2638 atomic_set(&cache->stats.demotion, 0);
2639 atomic_set(&cache->stats.promotion, 0);
2640 atomic_set(&cache->stats.copies_avoided, 0);
2641 atomic_set(&cache->stats.cache_cell_clash, 0);
2642 atomic_set(&cache->stats.commit_count, 0);
2643 atomic_set(&cache->stats.discard_count, 0);
2644
2645 spin_lock_init(&cache->invalidation_lock);
2646 INIT_LIST_HEAD(&cache->invalidation_requests);
2647
2648 batcher_init(&cache->committer, commit_op, cache,
2649 issue_op, cache, cache->wq);
2650 iot_init(&cache->tracker);
2651
2652 init_rwsem(&cache->background_work_lock);
2653 prevent_background_work(cache);
2654
2655 *result = cache;
2656 return 0;
2657bad:
2658 destroy(cache);
2659 return r;
2660}
2661
2662static int copy_ctr_args(struct cache *cache, int argc, const char **argv)
2663{
2664 unsigned i;
2665 const char **copy;
2666
2667 copy = kcalloc(argc, sizeof(*copy), GFP_KERNEL);
2668 if (!copy)
2669 return -ENOMEM;
2670 for (i = 0; i < argc; i++) {
2671 copy[i] = kstrdup(argv[i], GFP_KERNEL);
2672 if (!copy[i]) {
2673 while (i--)
2674 kfree(copy[i]);
2675 kfree(copy);
2676 return -ENOMEM;
2677 }
2678 }
2679
2680 cache->nr_ctr_args = argc;
2681 cache->ctr_args = copy;
2682
2683 return 0;
2684}
2685
2686static int cache_ctr(struct dm_target *ti, unsigned argc, char **argv)
2687{
2688 int r = -EINVAL;
2689 struct cache_args *ca;
2690 struct cache *cache = NULL;
2691
2692 ca = kzalloc(sizeof(*ca), GFP_KERNEL);
2693 if (!ca) {
2694 ti->error = "Error allocating memory for cache";
2695 return -ENOMEM;
2696 }
2697 ca->ti = ti;
2698
2699 r = parse_cache_args(ca, argc, argv, &ti->error);
2700 if (r)
2701 goto out;
2702
2703 r = cache_create(ca, &cache);
2704 if (r)
2705 goto out;
2706
2707 r = copy_ctr_args(cache, argc - 3, (const char **)argv + 3);
2708 if (r) {
2709 destroy(cache);
2710 goto out;
2711 }
2712
2713 ti->private = cache;
2714out:
2715 destroy_cache_args(ca);
2716 return r;
2717}
2718
2719/*----------------------------------------------------------------*/
2720
2721static int cache_map(struct dm_target *ti, struct bio *bio)
2722{
2723 struct cache *cache = ti->private;
2724
2725 int r;
2726 bool commit_needed;
2727 dm_oblock_t block = get_bio_block(cache, bio);
2728
2729 init_per_bio_data(bio);
2730 if (unlikely(from_oblock(block) >= from_oblock(cache->origin_blocks))) {
2731 /*
2732 * This can only occur if the io goes to a partial block at
2733 * the end of the origin device. We don't cache these.
2734 * Just remap to the origin and carry on.
2735 */
2736 remap_to_origin(cache, bio);
2737 accounted_begin(cache, bio);
2738 return DM_MAPIO_REMAPPED;
2739 }
2740
2741 if (discard_or_flush(bio)) {
2742 defer_bio(cache, bio);
2743 return DM_MAPIO_SUBMITTED;
2744 }
2745
2746 r = map_bio(cache, bio, block, &commit_needed);
2747 if (commit_needed)
2748 schedule_commit(&cache->committer);
2749
2750 return r;
2751}
2752
2753static int cache_end_io(struct dm_target *ti, struct bio *bio, blk_status_t *error)
2754{
2755 struct cache *cache = ti->private;
2756 unsigned long flags;
2757 struct per_bio_data *pb = get_per_bio_data(bio);
2758
2759 if (pb->tick) {
2760 policy_tick(cache->policy, false);
2761
2762 spin_lock_irqsave(&cache->lock, flags);
2763 cache->need_tick_bio = true;
2764 spin_unlock_irqrestore(&cache->lock, flags);
2765 }
2766
2767 bio_drop_shared_lock(cache, bio);
2768 accounted_complete(cache, bio);
2769
2770 return DM_ENDIO_DONE;
2771}
2772
2773static int write_dirty_bitset(struct cache *cache)
2774{
2775 int r;
2776
2777 if (get_cache_mode(cache) >= CM_READ_ONLY)
2778 return -EINVAL;
2779
2780 r = dm_cache_set_dirty_bits(cache->cmd, from_cblock(cache->cache_size), cache->dirty_bitset);
2781 if (r)
2782 metadata_operation_failed(cache, "dm_cache_set_dirty_bits", r);
2783
2784 return r;
2785}
2786
2787static int write_discard_bitset(struct cache *cache)
2788{
2789 unsigned i, r;
2790
2791 if (get_cache_mode(cache) >= CM_READ_ONLY)
2792 return -EINVAL;
2793
2794 r = dm_cache_discard_bitset_resize(cache->cmd, cache->discard_block_size,
2795 cache->discard_nr_blocks);
2796 if (r) {
2797 DMERR("%s: could not resize on-disk discard bitset", cache_device_name(cache));
2798 metadata_operation_failed(cache, "dm_cache_discard_bitset_resize", r);
2799 return r;
2800 }
2801
2802 for (i = 0; i < from_dblock(cache->discard_nr_blocks); i++) {
2803 r = dm_cache_set_discard(cache->cmd, to_dblock(i),
2804 is_discarded(cache, to_dblock(i)));
2805 if (r) {
2806 metadata_operation_failed(cache, "dm_cache_set_discard", r);
2807 return r;
2808 }
2809 }
2810
2811 return 0;
2812}
2813
2814static int write_hints(struct cache *cache)
2815{
2816 int r;
2817
2818 if (get_cache_mode(cache) >= CM_READ_ONLY)
2819 return -EINVAL;
2820
2821 r = dm_cache_write_hints(cache->cmd, cache->policy);
2822 if (r) {
2823 metadata_operation_failed(cache, "dm_cache_write_hints", r);
2824 return r;
2825 }
2826
2827 return 0;
2828}
2829
2830/*
2831 * returns true on success
2832 */
2833static bool sync_metadata(struct cache *cache)
2834{
2835 int r1, r2, r3, r4;
2836
2837 r1 = write_dirty_bitset(cache);
2838 if (r1)
2839 DMERR("%s: could not write dirty bitset", cache_device_name(cache));
2840
2841 r2 = write_discard_bitset(cache);
2842 if (r2)
2843 DMERR("%s: could not write discard bitset", cache_device_name(cache));
2844
2845 save_stats(cache);
2846
2847 r3 = write_hints(cache);
2848 if (r3)
2849 DMERR("%s: could not write hints", cache_device_name(cache));
2850
2851 /*
2852 * If writing the above metadata failed, we still commit, but don't
2853 * set the clean shutdown flag. This will effectively force every
2854 * dirty bit to be set on reload.
2855 */
2856 r4 = commit(cache, !r1 && !r2 && !r3);
2857 if (r4)
2858 DMERR("%s: could not write cache metadata", cache_device_name(cache));
2859
2860 return !r1 && !r2 && !r3 && !r4;
2861}
2862
2863static void cache_postsuspend(struct dm_target *ti)
2864{
2865 struct cache *cache = ti->private;
2866
2867 prevent_background_work(cache);
2868 BUG_ON(atomic_read(&cache->nr_io_migrations));
2869
2870 cancel_delayed_work(&cache->waker);
2871 flush_workqueue(cache->wq);
2872 WARN_ON(cache->tracker.in_flight);
2873
2874 /*
2875 * If it's a flush suspend there won't be any deferred bios, so this
2876 * call is harmless.
2877 */
2878 requeue_deferred_bios(cache);
2879
2880 if (get_cache_mode(cache) == CM_WRITE)
2881 (void) sync_metadata(cache);
2882}
2883
2884static int load_mapping(void *context, dm_oblock_t oblock, dm_cblock_t cblock,
2885 bool dirty, uint32_t hint, bool hint_valid)
2886{
2887 int r;
2888 struct cache *cache = context;
2889
2890 if (dirty) {
2891 set_bit(from_cblock(cblock), cache->dirty_bitset);
2892 atomic_inc(&cache->nr_dirty);
2893 } else
2894 clear_bit(from_cblock(cblock), cache->dirty_bitset);
2895
2896 r = policy_load_mapping(cache->policy, oblock, cblock, dirty, hint, hint_valid);
2897 if (r)
2898 return r;
2899
2900 return 0;
2901}
2902
2903/*
2904 * The discard block size in the on disk metadata is not
2905 * neccessarily the same as we're currently using. So we have to
2906 * be careful to only set the discarded attribute if we know it
2907 * covers a complete block of the new size.
2908 */
2909struct discard_load_info {
2910 struct cache *cache;
2911
2912 /*
2913 * These blocks are sized using the on disk dblock size, rather
2914 * than the current one.
2915 */
2916 dm_block_t block_size;
2917 dm_block_t discard_begin, discard_end;
2918};
2919
2920static void discard_load_info_init(struct cache *cache,
2921 struct discard_load_info *li)
2922{
2923 li->cache = cache;
2924 li->discard_begin = li->discard_end = 0;
2925}
2926
2927static void set_discard_range(struct discard_load_info *li)
2928{
2929 sector_t b, e;
2930
2931 if (li->discard_begin == li->discard_end)
2932 return;
2933
2934 /*
2935 * Convert to sectors.
2936 */
2937 b = li->discard_begin * li->block_size;
2938 e = li->discard_end * li->block_size;
2939
2940 /*
2941 * Then convert back to the current dblock size.
2942 */
2943 b = dm_sector_div_up(b, li->cache->discard_block_size);
2944 sector_div(e, li->cache->discard_block_size);
2945
2946 /*
2947 * The origin may have shrunk, so we need to check we're still in
2948 * bounds.
2949 */
2950 if (e > from_dblock(li->cache->discard_nr_blocks))
2951 e = from_dblock(li->cache->discard_nr_blocks);
2952
2953 for (; b < e; b++)
2954 set_discard(li->cache, to_dblock(b));
2955}
2956
2957static int load_discard(void *context, sector_t discard_block_size,
2958 dm_dblock_t dblock, bool discard)
2959{
2960 struct discard_load_info *li = context;
2961
2962 li->block_size = discard_block_size;
2963
2964 if (discard) {
2965 if (from_dblock(dblock) == li->discard_end)
2966 /*
2967 * We're already in a discard range, just extend it.
2968 */
2969 li->discard_end = li->discard_end + 1ULL;
2970
2971 else {
2972 /*
2973 * Emit the old range and start a new one.
2974 */
2975 set_discard_range(li);
2976 li->discard_begin = from_dblock(dblock);
2977 li->discard_end = li->discard_begin + 1ULL;
2978 }
2979 } else {
2980 set_discard_range(li);
2981 li->discard_begin = li->discard_end = 0;
2982 }
2983
2984 return 0;
2985}
2986
2987static dm_cblock_t get_cache_dev_size(struct cache *cache)
2988{
2989 sector_t size = get_dev_size(cache->cache_dev);
2990 (void) sector_div(size, cache->sectors_per_block);
2991 return to_cblock(size);
2992}
2993
2994static bool can_resize(struct cache *cache, dm_cblock_t new_size)
2995{
2996 if (from_cblock(new_size) > from_cblock(cache->cache_size)) {
2997 if (cache->sized) {
2998 DMERR("%s: unable to extend cache due to missing cache table reload",
2999 cache_device_name(cache));
3000 return false;
3001 }
3002 }
3003
3004 /*
3005 * We can't drop a dirty block when shrinking the cache.
3006 */
3007 while (from_cblock(new_size) < from_cblock(cache->cache_size)) {
3008 new_size = to_cblock(from_cblock(new_size) + 1);
3009 if (is_dirty(cache, new_size)) {
3010 DMERR("%s: unable to shrink cache; cache block %llu is dirty",
3011 cache_device_name(cache),
3012 (unsigned long long) from_cblock(new_size));
3013 return false;
3014 }
3015 }
3016
3017 return true;
3018}
3019
3020static int resize_cache_dev(struct cache *cache, dm_cblock_t new_size)
3021{
3022 int r;
3023
3024 r = dm_cache_resize(cache->cmd, new_size);
3025 if (r) {
3026 DMERR("%s: could not resize cache metadata", cache_device_name(cache));
3027 metadata_operation_failed(cache, "dm_cache_resize", r);
3028 return r;
3029 }
3030
3031 set_cache_size(cache, new_size);
3032
3033 return 0;
3034}
3035
3036static int cache_preresume(struct dm_target *ti)
3037{
3038 int r = 0;
3039 struct cache *cache = ti->private;
3040 dm_cblock_t csize = get_cache_dev_size(cache);
3041
3042 /*
3043 * Check to see if the cache has resized.
3044 */
3045 if (!cache->sized) {
3046 r = resize_cache_dev(cache, csize);
3047 if (r)
3048 return r;
3049
3050 cache->sized = true;
3051
3052 } else if (csize != cache->cache_size) {
3053 if (!can_resize(cache, csize))
3054 return -EINVAL;
3055
3056 r = resize_cache_dev(cache, csize);
3057 if (r)
3058 return r;
3059 }
3060
3061 if (!cache->loaded_mappings) {
3062 r = dm_cache_load_mappings(cache->cmd, cache->policy,
3063 load_mapping, cache);
3064 if (r) {
3065 DMERR("%s: could not load cache mappings", cache_device_name(cache));
3066 metadata_operation_failed(cache, "dm_cache_load_mappings", r);
3067 return r;
3068 }
3069
3070 cache->loaded_mappings = true;
3071 }
3072
3073 if (!cache->loaded_discards) {
3074 struct discard_load_info li;
3075
3076 /*
3077 * The discard bitset could have been resized, or the
3078 * discard block size changed. To be safe we start by
3079 * setting every dblock to not discarded.
3080 */
3081 clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks));
3082
3083 discard_load_info_init(cache, &li);
3084 r = dm_cache_load_discards(cache->cmd, load_discard, &li);
3085 if (r) {
3086 DMERR("%s: could not load origin discards", cache_device_name(cache));
3087 metadata_operation_failed(cache, "dm_cache_load_discards", r);
3088 return r;
3089 }
3090 set_discard_range(&li);
3091
3092 cache->loaded_discards = true;
3093 }
3094
3095 return r;
3096}
3097
3098static void cache_resume(struct dm_target *ti)
3099{
3100 struct cache *cache = ti->private;
3101
3102 cache->need_tick_bio = true;
3103 allow_background_work(cache);
3104 do_waker(&cache->waker.work);
3105}
3106
3107static void emit_flags(struct cache *cache, char *result,
3108 unsigned maxlen, ssize_t *sz_ptr)
3109{
3110 ssize_t sz = *sz_ptr;
3111 struct cache_features *cf = &cache->features;
3112 unsigned count = (cf->metadata_version == 2) + !cf->discard_passdown + 1;
3113
3114 DMEMIT("%u ", count);
3115
3116 if (cf->metadata_version == 2)
3117 DMEMIT("metadata2 ");
3118
3119 if (writethrough_mode(cache))
3120 DMEMIT("writethrough ");
3121
3122 else if (passthrough_mode(cache))
3123 DMEMIT("passthrough ");
3124
3125 else if (writeback_mode(cache))
3126 DMEMIT("writeback ");
3127
3128 else {
3129 DMEMIT("unknown ");
3130 DMERR("%s: internal error: unknown io mode: %d",
3131 cache_device_name(cache), (int) cf->io_mode);
3132 }
3133
3134 if (!cf->discard_passdown)
3135 DMEMIT("no_discard_passdown ");
3136
3137 *sz_ptr = sz;
3138}
3139
3140/*
3141 * Status format:
3142 *
3143 * <metadata block size> <#used metadata blocks>/<#total metadata blocks>
3144 * <cache block size> <#used cache blocks>/<#total cache blocks>
3145 * <#read hits> <#read misses> <#write hits> <#write misses>
3146 * <#demotions> <#promotions> <#dirty>
3147 * <#features> <features>*
3148 * <#core args> <core args>
3149 * <policy name> <#policy args> <policy args>* <cache metadata mode> <needs_check>
3150 */
3151static void cache_status(struct dm_target *ti, status_type_t type,
3152 unsigned status_flags, char *result, unsigned maxlen)
3153{
3154 int r = 0;
3155 unsigned i;
3156 ssize_t sz = 0;
3157 dm_block_t nr_free_blocks_metadata = 0;
3158 dm_block_t nr_blocks_metadata = 0;
3159 char buf[BDEVNAME_SIZE];
3160 struct cache *cache = ti->private;
3161 dm_cblock_t residency;
3162 bool needs_check;
3163
3164 switch (type) {
3165 case STATUSTYPE_INFO:
3166 if (get_cache_mode(cache) == CM_FAIL) {
3167 DMEMIT("Fail");
3168 break;
3169 }
3170
3171 /* Commit to ensure statistics aren't out-of-date */
3172 if (!(status_flags & DM_STATUS_NOFLUSH_FLAG) && !dm_suspended(ti))
3173 (void) commit(cache, false);
3174
3175 r = dm_cache_get_free_metadata_block_count(cache->cmd, &nr_free_blocks_metadata);
3176 if (r) {
3177 DMERR("%s: dm_cache_get_free_metadata_block_count returned %d",
3178 cache_device_name(cache), r);
3179 goto err;
3180 }
3181
3182 r = dm_cache_get_metadata_dev_size(cache->cmd, &nr_blocks_metadata);
3183 if (r) {
3184 DMERR("%s: dm_cache_get_metadata_dev_size returned %d",
3185 cache_device_name(cache), r);
3186 goto err;
3187 }
3188
3189 residency = policy_residency(cache->policy);
3190
3191 DMEMIT("%u %llu/%llu %llu %llu/%llu %u %u %u %u %u %u %lu ",
3192 (unsigned)DM_CACHE_METADATA_BLOCK_SIZE,
3193 (unsigned long long)(nr_blocks_metadata - nr_free_blocks_metadata),
3194 (unsigned long long)nr_blocks_metadata,
3195 (unsigned long long)cache->sectors_per_block,
3196 (unsigned long long) from_cblock(residency),
3197 (unsigned long long) from_cblock(cache->cache_size),
3198 (unsigned) atomic_read(&cache->stats.read_hit),
3199 (unsigned) atomic_read(&cache->stats.read_miss),
3200 (unsigned) atomic_read(&cache->stats.write_hit),
3201 (unsigned) atomic_read(&cache->stats.write_miss),
3202 (unsigned) atomic_read(&cache->stats.demotion),
3203 (unsigned) atomic_read(&cache->stats.promotion),
3204 (unsigned long) atomic_read(&cache->nr_dirty));
3205
3206 emit_flags(cache, result, maxlen, &sz);
3207
3208 DMEMIT("2 migration_threshold %llu ", (unsigned long long) cache->migration_threshold);
3209
3210 DMEMIT("%s ", dm_cache_policy_get_name(cache->policy));
3211 if (sz < maxlen) {
3212 r = policy_emit_config_values(cache->policy, result, maxlen, &sz);
3213 if (r)
3214 DMERR("%s: policy_emit_config_values returned %d",
3215 cache_device_name(cache), r);
3216 }
3217
3218 if (get_cache_mode(cache) == CM_READ_ONLY)
3219 DMEMIT("ro ");
3220 else
3221 DMEMIT("rw ");
3222
3223 r = dm_cache_metadata_needs_check(cache->cmd, &needs_check);
3224
3225 if (r || needs_check)
3226 DMEMIT("needs_check ");
3227 else
3228 DMEMIT("- ");
3229
3230 break;
3231
3232 case STATUSTYPE_TABLE:
3233 format_dev_t(buf, cache->metadata_dev->bdev->bd_dev);
3234 DMEMIT("%s ", buf);
3235 format_dev_t(buf, cache->cache_dev->bdev->bd_dev);
3236 DMEMIT("%s ", buf);
3237 format_dev_t(buf, cache->origin_dev->bdev->bd_dev);
3238 DMEMIT("%s", buf);
3239
3240 for (i = 0; i < cache->nr_ctr_args - 1; i++)
3241 DMEMIT(" %s", cache->ctr_args[i]);
3242 if (cache->nr_ctr_args)
3243 DMEMIT(" %s", cache->ctr_args[cache->nr_ctr_args - 1]);
3244 }
3245
3246 return;
3247
3248err:
3249 DMEMIT("Error");
3250}
3251
3252/*
3253 * Defines a range of cblocks, begin to (end - 1) are in the range. end is
3254 * the one-past-the-end value.
3255 */
3256struct cblock_range {
3257 dm_cblock_t begin;
3258 dm_cblock_t end;
3259};
3260
3261/*
3262 * A cache block range can take two forms:
3263 *
3264 * i) A single cblock, eg. '3456'
3265 * ii) A begin and end cblock with a dash between, eg. 123-234
3266 */
3267static int parse_cblock_range(struct cache *cache, const char *str,
3268 struct cblock_range *result)
3269{
3270 char dummy;
3271 uint64_t b, e;
3272 int r;
3273
3274 /*
3275 * Try and parse form (ii) first.
3276 */
3277 r = sscanf(str, "%llu-%llu%c", &b, &e, &dummy);
3278 if (r < 0)
3279 return r;
3280
3281 if (r == 2) {
3282 result->begin = to_cblock(b);
3283 result->end = to_cblock(e);
3284 return 0;
3285 }
3286
3287 /*
3288 * That didn't work, try form (i).
3289 */
3290 r = sscanf(str, "%llu%c", &b, &dummy);
3291 if (r < 0)
3292 return r;
3293
3294 if (r == 1) {
3295 result->begin = to_cblock(b);
3296 result->end = to_cblock(from_cblock(result->begin) + 1u);
3297 return 0;
3298 }
3299
3300 DMERR("%s: invalid cblock range '%s'", cache_device_name(cache), str);
3301 return -EINVAL;
3302}
3303
3304static int validate_cblock_range(struct cache *cache, struct cblock_range *range)
3305{
3306 uint64_t b = from_cblock(range->begin);
3307 uint64_t e = from_cblock(range->end);
3308 uint64_t n = from_cblock(cache->cache_size);
3309
3310 if (b >= n) {
3311 DMERR("%s: begin cblock out of range: %llu >= %llu",
3312 cache_device_name(cache), b, n);
3313 return -EINVAL;
3314 }
3315
3316 if (e > n) {
3317 DMERR("%s: end cblock out of range: %llu > %llu",
3318 cache_device_name(cache), e, n);
3319 return -EINVAL;
3320 }
3321
3322 if (b >= e) {
3323 DMERR("%s: invalid cblock range: %llu >= %llu",
3324 cache_device_name(cache), b, e);
3325 return -EINVAL;
3326 }
3327
3328 return 0;
3329}
3330
3331static inline dm_cblock_t cblock_succ(dm_cblock_t b)
3332{
3333 return to_cblock(from_cblock(b) + 1);
3334}
3335
3336static int request_invalidation(struct cache *cache, struct cblock_range *range)
3337{
3338 int r = 0;
3339
3340 /*
3341 * We don't need to do any locking here because we know we're in
3342 * passthrough mode. There's is potential for a race between an
3343 * invalidation triggered by an io and an invalidation message. This
3344 * is harmless, we must not worry if the policy call fails.
3345 */
3346 while (range->begin != range->end) {
3347 r = invalidate_cblock(cache, range->begin);
3348 if (r)
3349 return r;
3350
3351 range->begin = cblock_succ(range->begin);
3352 }
3353
3354 cache->commit_requested = true;
3355 return r;
3356}
3357
3358static int process_invalidate_cblocks_message(struct cache *cache, unsigned count,
3359 const char **cblock_ranges)
3360{
3361 int r = 0;
3362 unsigned i;
3363 struct cblock_range range;
3364
3365 if (!passthrough_mode(cache)) {
3366 DMERR("%s: cache has to be in passthrough mode for invalidation",
3367 cache_device_name(cache));
3368 return -EPERM;
3369 }
3370
3371 for (i = 0; i < count; i++) {
3372 r = parse_cblock_range(cache, cblock_ranges[i], &range);
3373 if (r)
3374 break;
3375
3376 r = validate_cblock_range(cache, &range);
3377 if (r)
3378 break;
3379
3380 /*
3381 * Pass begin and end origin blocks to the worker and wake it.
3382 */
3383 r = request_invalidation(cache, &range);
3384 if (r)
3385 break;
3386 }
3387
3388 return r;
3389}
3390
3391/*
3392 * Supports
3393 * "<key> <value>"
3394 * and
3395 * "invalidate_cblocks [(<begin>)|(<begin>-<end>)]*
3396 *
3397 * The key migration_threshold is supported by the cache target core.
3398 */
3399static int cache_message(struct dm_target *ti, unsigned argc, char **argv,
3400 char *result, unsigned maxlen)
3401{
3402 struct cache *cache = ti->private;
3403
3404 if (!argc)
3405 return -EINVAL;
3406
3407 if (get_cache_mode(cache) >= CM_READ_ONLY) {
3408 DMERR("%s: unable to service cache target messages in READ_ONLY or FAIL mode",
3409 cache_device_name(cache));
3410 return -EOPNOTSUPP;
3411 }
3412
3413 if (!strcasecmp(argv[0], "invalidate_cblocks"))
3414 return process_invalidate_cblocks_message(cache, argc - 1, (const char **) argv + 1);
3415
3416 if (argc != 2)
3417 return -EINVAL;
3418
3419 return set_config_value(cache, argv[0], argv[1]);
3420}
3421
3422static int cache_iterate_devices(struct dm_target *ti,
3423 iterate_devices_callout_fn fn, void *data)
3424{
3425 int r = 0;
3426 struct cache *cache = ti->private;
3427
3428 r = fn(ti, cache->cache_dev, 0, get_dev_size(cache->cache_dev), data);
3429 if (!r)
3430 r = fn(ti, cache->origin_dev, 0, ti->len, data);
3431
3432 return r;
3433}
3434
3435static bool origin_dev_supports_discard(struct block_device *origin_bdev)
3436{
3437 struct request_queue *q = bdev_get_queue(origin_bdev);
3438
3439 return q && blk_queue_discard(q);
3440}
3441
3442/*
3443 * If discard_passdown was enabled verify that the origin device
3444 * supports discards. Disable discard_passdown if not.
3445 */
3446static void disable_passdown_if_not_supported(struct cache *cache)
3447{
3448 struct block_device *origin_bdev = cache->origin_dev->bdev;
3449 struct queue_limits *origin_limits = &bdev_get_queue(origin_bdev)->limits;
3450 const char *reason = NULL;
3451 char buf[BDEVNAME_SIZE];
3452
3453 if (!cache->features.discard_passdown)
3454 return;
3455
3456 if (!origin_dev_supports_discard(origin_bdev))
3457 reason = "discard unsupported";
3458
3459 else if (origin_limits->max_discard_sectors < cache->sectors_per_block)
3460 reason = "max discard sectors smaller than a block";
3461
3462 if (reason) {
3463 DMWARN("Origin device (%s) %s: Disabling discard passdown.",
3464 bdevname(origin_bdev, buf), reason);
3465 cache->features.discard_passdown = false;
3466 }
3467}
3468
3469static void set_discard_limits(struct cache *cache, struct queue_limits *limits)
3470{
3471 struct block_device *origin_bdev = cache->origin_dev->bdev;
3472 struct queue_limits *origin_limits = &bdev_get_queue(origin_bdev)->limits;
3473
3474 if (!cache->features.discard_passdown) {
3475 /* No passdown is done so setting own virtual limits */
3476 limits->max_discard_sectors = min_t(sector_t, cache->discard_block_size * 1024,
3477 cache->origin_sectors);
3478 limits->discard_granularity = cache->discard_block_size << SECTOR_SHIFT;
3479 return;
3480 }
3481
3482 /*
3483 * cache_iterate_devices() is stacking both origin and fast device limits
3484 * but discards aren't passed to fast device, so inherit origin's limits.
3485 */
3486 limits->max_discard_sectors = origin_limits->max_discard_sectors;
3487 limits->max_hw_discard_sectors = origin_limits->max_hw_discard_sectors;
3488 limits->discard_granularity = origin_limits->discard_granularity;
3489 limits->discard_alignment = origin_limits->discard_alignment;
3490 limits->discard_misaligned = origin_limits->discard_misaligned;
3491}
3492
3493static void cache_io_hints(struct dm_target *ti, struct queue_limits *limits)
3494{
3495 struct cache *cache = ti->private;
3496 uint64_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;
3497
3498 /*
3499 * If the system-determined stacked limits are compatible with the
3500 * cache's blocksize (io_opt is a factor) do not override them.
3501 */
3502 if (io_opt_sectors < cache->sectors_per_block ||
3503 do_div(io_opt_sectors, cache->sectors_per_block)) {
3504 blk_limits_io_min(limits, cache->sectors_per_block << SECTOR_SHIFT);
3505 blk_limits_io_opt(limits, cache->sectors_per_block << SECTOR_SHIFT);
3506 }
3507
3508 disable_passdown_if_not_supported(cache);
3509 set_discard_limits(cache, limits);
3510}
3511
3512/*----------------------------------------------------------------*/
3513
3514static struct target_type cache_target = {
3515 .name = "cache",
3516 .version = {2, 1, 0},
3517 .module = THIS_MODULE,
3518 .ctr = cache_ctr,
3519 .dtr = cache_dtr,
3520 .map = cache_map,
3521 .end_io = cache_end_io,
3522 .postsuspend = cache_postsuspend,
3523 .preresume = cache_preresume,
3524 .resume = cache_resume,
3525 .status = cache_status,
3526 .message = cache_message,
3527 .iterate_devices = cache_iterate_devices,
3528 .io_hints = cache_io_hints,
3529};
3530
3531static int __init dm_cache_init(void)
3532{
3533 int r;
3534
3535 migration_cache = KMEM_CACHE(dm_cache_migration, 0);
3536 if (!migration_cache)
3537 return -ENOMEM;
3538
3539 r = dm_register_target(&cache_target);
3540 if (r) {
3541 DMERR("cache target registration failed: %d", r);
3542 kmem_cache_destroy(migration_cache);
3543 return r;
3544 }
3545
3546 return 0;
3547}
3548
3549static void __exit dm_cache_exit(void)
3550{
3551 dm_unregister_target(&cache_target);
3552 kmem_cache_destroy(migration_cache);
3553}
3554
3555module_init(dm_cache_init);
3556module_exit(dm_cache_exit);
3557
3558MODULE_DESCRIPTION(DM_NAME " cache target");
3559MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
3560MODULE_LICENSE("GPL");