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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2012 Red Hat. All rights reserved.
4 *
5 * This file is released under the GPL.
6 */
7
8#include "dm.h"
9#include "dm-bio-prison-v2.h"
10#include "dm-bio-record.h"
11#include "dm-cache-metadata.h"
12#include "dm-io-tracker.h"
13
14#include <linux/dm-io.h>
15#include <linux/dm-kcopyd.h>
16#include <linux/jiffies.h>
17#include <linux/init.h>
18#include <linux/mempool.h>
19#include <linux/module.h>
20#include <linux/rwsem.h>
21#include <linux/slab.h>
22#include <linux/vmalloc.h>
23
24#define DM_MSG_PREFIX "cache"
25
26DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(cache_copy_throttle,
27 "A percentage of time allocated for copying to and/or from cache");
28
29/*----------------------------------------------------------------*/
30
31/*
32 * Glossary:
33 *
34 * oblock: index of an origin block
35 * cblock: index of a cache block
36 * promotion: movement of a block from origin to cache
37 * demotion: movement of a block from cache to origin
38 * migration: movement of a block between the origin and cache device,
39 * either direction
40 */
41
42/*----------------------------------------------------------------*/
43
44/*
45 * Represents a chunk of future work. 'input' allows continuations to pass
46 * values between themselves, typically error values.
47 */
48struct continuation {
49 struct work_struct ws;
50 blk_status_t input;
51};
52
53static inline void init_continuation(struct continuation *k,
54 void (*fn)(struct work_struct *))
55{
56 INIT_WORK(&k->ws, fn);
57 k->input = 0;
58}
59
60static inline void queue_continuation(struct workqueue_struct *wq,
61 struct continuation *k)
62{
63 queue_work(wq, &k->ws);
64}
65
66/*----------------------------------------------------------------*/
67
68/*
69 * The batcher collects together pieces of work that need a particular
70 * operation to occur before they can proceed (typically a commit).
71 */
72struct batcher {
73 /*
74 * The operation that everyone is waiting for.
75 */
76 blk_status_t (*commit_op)(void *context);
77 void *commit_context;
78
79 /*
80 * This is how bios should be issued once the commit op is complete
81 * (accounted_request).
82 */
83 void (*issue_op)(struct bio *bio, void *context);
84 void *issue_context;
85
86 /*
87 * Queued work gets put on here after commit.
88 */
89 struct workqueue_struct *wq;
90
91 spinlock_t lock;
92 struct list_head work_items;
93 struct bio_list bios;
94 struct work_struct commit_work;
95
96 bool commit_scheduled;
97};
98
99static void __commit(struct work_struct *_ws)
100{
101 struct batcher *b = container_of(_ws, struct batcher, commit_work);
102 blk_status_t r;
103 struct list_head work_items;
104 struct work_struct *ws, *tmp;
105 struct continuation *k;
106 struct bio *bio;
107 struct bio_list bios;
108
109 INIT_LIST_HEAD(&work_items);
110 bio_list_init(&bios);
111
112 /*
113 * We have to grab these before the commit_op to avoid a race
114 * condition.
115 */
116 spin_lock_irq(&b->lock);
117 list_splice_init(&b->work_items, &work_items);
118 bio_list_merge(&bios, &b->bios);
119 bio_list_init(&b->bios);
120 b->commit_scheduled = false;
121 spin_unlock_irq(&b->lock);
122
123 r = b->commit_op(b->commit_context);
124
125 list_for_each_entry_safe(ws, tmp, &work_items, entry) {
126 k = container_of(ws, struct continuation, ws);
127 k->input = r;
128 INIT_LIST_HEAD(&ws->entry); /* to avoid a WARN_ON */
129 queue_work(b->wq, ws);
130 }
131
132 while ((bio = bio_list_pop(&bios))) {
133 if (r) {
134 bio->bi_status = r;
135 bio_endio(bio);
136 } else
137 b->issue_op(bio, b->issue_context);
138 }
139}
140
141static void batcher_init(struct batcher *b,
142 blk_status_t (*commit_op)(void *),
143 void *commit_context,
144 void (*issue_op)(struct bio *bio, void *),
145 void *issue_context,
146 struct workqueue_struct *wq)
147{
148 b->commit_op = commit_op;
149 b->commit_context = commit_context;
150 b->issue_op = issue_op;
151 b->issue_context = issue_context;
152 b->wq = wq;
153
154 spin_lock_init(&b->lock);
155 INIT_LIST_HEAD(&b->work_items);
156 bio_list_init(&b->bios);
157 INIT_WORK(&b->commit_work, __commit);
158 b->commit_scheduled = false;
159}
160
161static void async_commit(struct batcher *b)
162{
163 queue_work(b->wq, &b->commit_work);
164}
165
166static void continue_after_commit(struct batcher *b, struct continuation *k)
167{
168 bool commit_scheduled;
169
170 spin_lock_irq(&b->lock);
171 commit_scheduled = b->commit_scheduled;
172 list_add_tail(&k->ws.entry, &b->work_items);
173 spin_unlock_irq(&b->lock);
174
175 if (commit_scheduled)
176 async_commit(b);
177}
178
179/*
180 * Bios are errored if commit failed.
181 */
182static void issue_after_commit(struct batcher *b, struct bio *bio)
183{
184 bool commit_scheduled;
185
186 spin_lock_irq(&b->lock);
187 commit_scheduled = b->commit_scheduled;
188 bio_list_add(&b->bios, bio);
189 spin_unlock_irq(&b->lock);
190
191 if (commit_scheduled)
192 async_commit(b);
193}
194
195/*
196 * Call this if some urgent work is waiting for the commit to complete.
197 */
198static void schedule_commit(struct batcher *b)
199{
200 bool immediate;
201
202 spin_lock_irq(&b->lock);
203 immediate = !list_empty(&b->work_items) || !bio_list_empty(&b->bios);
204 b->commit_scheduled = true;
205 spin_unlock_irq(&b->lock);
206
207 if (immediate)
208 async_commit(b);
209}
210
211/*
212 * There are a couple of places where we let a bio run, but want to do some
213 * work before calling its endio function. We do this by temporarily
214 * changing the endio fn.
215 */
216struct dm_hook_info {
217 bio_end_io_t *bi_end_io;
218};
219
220static void dm_hook_bio(struct dm_hook_info *h, struct bio *bio,
221 bio_end_io_t *bi_end_io, void *bi_private)
222{
223 h->bi_end_io = bio->bi_end_io;
224
225 bio->bi_end_io = bi_end_io;
226 bio->bi_private = bi_private;
227}
228
229static void dm_unhook_bio(struct dm_hook_info *h, struct bio *bio)
230{
231 bio->bi_end_io = h->bi_end_io;
232}
233
234/*----------------------------------------------------------------*/
235
236#define MIGRATION_POOL_SIZE 128
237#define COMMIT_PERIOD HZ
238#define MIGRATION_COUNT_WINDOW 10
239
240/*
241 * The block size of the device holding cache data must be
242 * between 32KB and 1GB.
243 */
244#define DATA_DEV_BLOCK_SIZE_MIN_SECTORS (32 * 1024 >> SECTOR_SHIFT)
245#define DATA_DEV_BLOCK_SIZE_MAX_SECTORS (1024 * 1024 * 1024 >> SECTOR_SHIFT)
246
247enum cache_metadata_mode {
248 CM_WRITE, /* metadata may be changed */
249 CM_READ_ONLY, /* metadata may not be changed */
250 CM_FAIL
251};
252
253enum cache_io_mode {
254 /*
255 * Data is written to cached blocks only. These blocks are marked
256 * dirty. If you lose the cache device you will lose data.
257 * Potential performance increase for both reads and writes.
258 */
259 CM_IO_WRITEBACK,
260
261 /*
262 * Data is written to both cache and origin. Blocks are never
263 * dirty. Potential performance benfit for reads only.
264 */
265 CM_IO_WRITETHROUGH,
266
267 /*
268 * A degraded mode useful for various cache coherency situations
269 * (eg, rolling back snapshots). Reads and writes always go to the
270 * origin. If a write goes to a cached oblock, then the cache
271 * block is invalidated.
272 */
273 CM_IO_PASSTHROUGH
274};
275
276struct cache_features {
277 enum cache_metadata_mode mode;
278 enum cache_io_mode io_mode;
279 unsigned int metadata_version;
280 bool discard_passdown:1;
281};
282
283struct cache_stats {
284 atomic_t read_hit;
285 atomic_t read_miss;
286 atomic_t write_hit;
287 atomic_t write_miss;
288 atomic_t demotion;
289 atomic_t promotion;
290 atomic_t writeback;
291 atomic_t copies_avoided;
292 atomic_t cache_cell_clash;
293 atomic_t commit_count;
294 atomic_t discard_count;
295};
296
297struct cache {
298 struct dm_target *ti;
299 spinlock_t lock;
300
301 /*
302 * Fields for converting from sectors to blocks.
303 */
304 int sectors_per_block_shift;
305 sector_t sectors_per_block;
306
307 struct dm_cache_metadata *cmd;
308
309 /*
310 * Metadata is written to this device.
311 */
312 struct dm_dev *metadata_dev;
313
314 /*
315 * The slower of the two data devices. Typically a spindle.
316 */
317 struct dm_dev *origin_dev;
318
319 /*
320 * The faster of the two data devices. Typically an SSD.
321 */
322 struct dm_dev *cache_dev;
323
324 /*
325 * Size of the origin device in _complete_ blocks and native sectors.
326 */
327 dm_oblock_t origin_blocks;
328 sector_t origin_sectors;
329
330 /*
331 * Size of the cache device in blocks.
332 */
333 dm_cblock_t cache_size;
334
335 /*
336 * Invalidation fields.
337 */
338 spinlock_t invalidation_lock;
339 struct list_head invalidation_requests;
340
341 sector_t migration_threshold;
342 wait_queue_head_t migration_wait;
343 atomic_t nr_allocated_migrations;
344
345 /*
346 * The number of in flight migrations that are performing
347 * background io. eg, promotion, writeback.
348 */
349 atomic_t nr_io_migrations;
350
351 struct bio_list deferred_bios;
352
353 struct rw_semaphore quiesce_lock;
354
355 /*
356 * origin_blocks entries, discarded if set.
357 */
358 dm_dblock_t discard_nr_blocks;
359 unsigned long *discard_bitset;
360 uint32_t discard_block_size; /* a power of 2 times sectors per block */
361
362 /*
363 * Rather than reconstructing the table line for the status we just
364 * save it and regurgitate.
365 */
366 unsigned int nr_ctr_args;
367 const char **ctr_args;
368
369 struct dm_kcopyd_client *copier;
370 struct work_struct deferred_bio_worker;
371 struct work_struct migration_worker;
372 struct workqueue_struct *wq;
373 struct delayed_work waker;
374 struct dm_bio_prison_v2 *prison;
375
376 /*
377 * cache_size entries, dirty if set
378 */
379 unsigned long *dirty_bitset;
380 atomic_t nr_dirty;
381
382 unsigned int policy_nr_args;
383 struct dm_cache_policy *policy;
384
385 /*
386 * Cache features such as write-through.
387 */
388 struct cache_features features;
389
390 struct cache_stats stats;
391
392 bool need_tick_bio:1;
393 bool sized:1;
394 bool invalidate:1;
395 bool commit_requested:1;
396 bool loaded_mappings:1;
397 bool loaded_discards:1;
398
399 struct rw_semaphore background_work_lock;
400
401 struct batcher committer;
402 struct work_struct commit_ws;
403
404 struct dm_io_tracker tracker;
405
406 mempool_t migration_pool;
407
408 struct bio_set bs;
409};
410
411struct per_bio_data {
412 bool tick:1;
413 unsigned int req_nr:2;
414 struct dm_bio_prison_cell_v2 *cell;
415 struct dm_hook_info hook_info;
416 sector_t len;
417};
418
419struct dm_cache_migration {
420 struct continuation k;
421 struct cache *cache;
422
423 struct policy_work *op;
424 struct bio *overwrite_bio;
425 struct dm_bio_prison_cell_v2 *cell;
426
427 dm_cblock_t invalidate_cblock;
428 dm_oblock_t invalidate_oblock;
429};
430
431/*----------------------------------------------------------------*/
432
433static bool writethrough_mode(struct cache *cache)
434{
435 return cache->features.io_mode == CM_IO_WRITETHROUGH;
436}
437
438static bool writeback_mode(struct cache *cache)
439{
440 return cache->features.io_mode == CM_IO_WRITEBACK;
441}
442
443static inline bool passthrough_mode(struct cache *cache)
444{
445 return unlikely(cache->features.io_mode == CM_IO_PASSTHROUGH);
446}
447
448/*----------------------------------------------------------------*/
449
450static void wake_deferred_bio_worker(struct cache *cache)
451{
452 queue_work(cache->wq, &cache->deferred_bio_worker);
453}
454
455static void wake_migration_worker(struct cache *cache)
456{
457 if (passthrough_mode(cache))
458 return;
459
460 queue_work(cache->wq, &cache->migration_worker);
461}
462
463/*----------------------------------------------------------------*/
464
465static struct dm_bio_prison_cell_v2 *alloc_prison_cell(struct cache *cache)
466{
467 return dm_bio_prison_alloc_cell_v2(cache->prison, GFP_NOIO);
468}
469
470static void free_prison_cell(struct cache *cache, struct dm_bio_prison_cell_v2 *cell)
471{
472 dm_bio_prison_free_cell_v2(cache->prison, cell);
473}
474
475static struct dm_cache_migration *alloc_migration(struct cache *cache)
476{
477 struct dm_cache_migration *mg;
478
479 mg = mempool_alloc(&cache->migration_pool, GFP_NOIO);
480
481 memset(mg, 0, sizeof(*mg));
482
483 mg->cache = cache;
484 atomic_inc(&cache->nr_allocated_migrations);
485
486 return mg;
487}
488
489static void free_migration(struct dm_cache_migration *mg)
490{
491 struct cache *cache = mg->cache;
492
493 if (atomic_dec_and_test(&cache->nr_allocated_migrations))
494 wake_up(&cache->migration_wait);
495
496 mempool_free(mg, &cache->migration_pool);
497}
498
499/*----------------------------------------------------------------*/
500
501static inline dm_oblock_t oblock_succ(dm_oblock_t b)
502{
503 return to_oblock(from_oblock(b) + 1ull);
504}
505
506static void build_key(dm_oblock_t begin, dm_oblock_t end, struct dm_cell_key_v2 *key)
507{
508 key->virtual = 0;
509 key->dev = 0;
510 key->block_begin = from_oblock(begin);
511 key->block_end = from_oblock(end);
512}
513
514/*
515 * We have two lock levels. Level 0, which is used to prevent WRITEs, and
516 * level 1 which prevents *both* READs and WRITEs.
517 */
518#define WRITE_LOCK_LEVEL 0
519#define READ_WRITE_LOCK_LEVEL 1
520
521static unsigned int lock_level(struct bio *bio)
522{
523 return bio_data_dir(bio) == WRITE ?
524 WRITE_LOCK_LEVEL :
525 READ_WRITE_LOCK_LEVEL;
526}
527
528/*
529 *--------------------------------------------------------------
530 * Per bio data
531 *--------------------------------------------------------------
532 */
533
534static struct per_bio_data *get_per_bio_data(struct bio *bio)
535{
536 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
537
538 BUG_ON(!pb);
539 return pb;
540}
541
542static struct per_bio_data *init_per_bio_data(struct bio *bio)
543{
544 struct per_bio_data *pb = get_per_bio_data(bio);
545
546 pb->tick = false;
547 pb->req_nr = dm_bio_get_target_bio_nr(bio);
548 pb->cell = NULL;
549 pb->len = 0;
550
551 return pb;
552}
553
554/*----------------------------------------------------------------*/
555
556static void defer_bio(struct cache *cache, struct bio *bio)
557{
558 spin_lock_irq(&cache->lock);
559 bio_list_add(&cache->deferred_bios, bio);
560 spin_unlock_irq(&cache->lock);
561
562 wake_deferred_bio_worker(cache);
563}
564
565static void defer_bios(struct cache *cache, struct bio_list *bios)
566{
567 spin_lock_irq(&cache->lock);
568 bio_list_merge(&cache->deferred_bios, bios);
569 bio_list_init(bios);
570 spin_unlock_irq(&cache->lock);
571
572 wake_deferred_bio_worker(cache);
573}
574
575/*----------------------------------------------------------------*/
576
577static bool bio_detain_shared(struct cache *cache, dm_oblock_t oblock, struct bio *bio)
578{
579 bool r;
580 struct per_bio_data *pb;
581 struct dm_cell_key_v2 key;
582 dm_oblock_t end = to_oblock(from_oblock(oblock) + 1ULL);
583 struct dm_bio_prison_cell_v2 *cell_prealloc, *cell;
584
585 cell_prealloc = alloc_prison_cell(cache); /* FIXME: allow wait if calling from worker */
586
587 build_key(oblock, end, &key);
588 r = dm_cell_get_v2(cache->prison, &key, lock_level(bio), bio, cell_prealloc, &cell);
589 if (!r) {
590 /*
591 * Failed to get the lock.
592 */
593 free_prison_cell(cache, cell_prealloc);
594 return r;
595 }
596
597 if (cell != cell_prealloc)
598 free_prison_cell(cache, cell_prealloc);
599
600 pb = get_per_bio_data(bio);
601 pb->cell = cell;
602
603 return r;
604}
605
606/*----------------------------------------------------------------*/
607
608static bool is_dirty(struct cache *cache, dm_cblock_t b)
609{
610 return test_bit(from_cblock(b), cache->dirty_bitset);
611}
612
613static void set_dirty(struct cache *cache, dm_cblock_t cblock)
614{
615 if (!test_and_set_bit(from_cblock(cblock), cache->dirty_bitset)) {
616 atomic_inc(&cache->nr_dirty);
617 policy_set_dirty(cache->policy, cblock);
618 }
619}
620
621/*
622 * These two are called when setting after migrations to force the policy
623 * and dirty bitset to be in sync.
624 */
625static void force_set_dirty(struct cache *cache, dm_cblock_t cblock)
626{
627 if (!test_and_set_bit(from_cblock(cblock), cache->dirty_bitset))
628 atomic_inc(&cache->nr_dirty);
629 policy_set_dirty(cache->policy, cblock);
630}
631
632static void force_clear_dirty(struct cache *cache, dm_cblock_t cblock)
633{
634 if (test_and_clear_bit(from_cblock(cblock), cache->dirty_bitset)) {
635 if (atomic_dec_return(&cache->nr_dirty) == 0)
636 dm_table_event(cache->ti->table);
637 }
638
639 policy_clear_dirty(cache->policy, cblock);
640}
641
642/*----------------------------------------------------------------*/
643
644static bool block_size_is_power_of_two(struct cache *cache)
645{
646 return cache->sectors_per_block_shift >= 0;
647}
648
649static dm_block_t block_div(dm_block_t b, uint32_t n)
650{
651 do_div(b, n);
652
653 return b;
654}
655
656static dm_block_t oblocks_per_dblock(struct cache *cache)
657{
658 dm_block_t oblocks = cache->discard_block_size;
659
660 if (block_size_is_power_of_two(cache))
661 oblocks >>= cache->sectors_per_block_shift;
662 else
663 oblocks = block_div(oblocks, cache->sectors_per_block);
664
665 return oblocks;
666}
667
668static dm_dblock_t oblock_to_dblock(struct cache *cache, dm_oblock_t oblock)
669{
670 return to_dblock(block_div(from_oblock(oblock),
671 oblocks_per_dblock(cache)));
672}
673
674static void set_discard(struct cache *cache, dm_dblock_t b)
675{
676 BUG_ON(from_dblock(b) >= from_dblock(cache->discard_nr_blocks));
677 atomic_inc(&cache->stats.discard_count);
678
679 spin_lock_irq(&cache->lock);
680 set_bit(from_dblock(b), cache->discard_bitset);
681 spin_unlock_irq(&cache->lock);
682}
683
684static void clear_discard(struct cache *cache, dm_dblock_t b)
685{
686 spin_lock_irq(&cache->lock);
687 clear_bit(from_dblock(b), cache->discard_bitset);
688 spin_unlock_irq(&cache->lock);
689}
690
691static bool is_discarded(struct cache *cache, dm_dblock_t b)
692{
693 int r;
694
695 spin_lock_irq(&cache->lock);
696 r = test_bit(from_dblock(b), cache->discard_bitset);
697 spin_unlock_irq(&cache->lock);
698
699 return r;
700}
701
702static bool is_discarded_oblock(struct cache *cache, dm_oblock_t b)
703{
704 int r;
705
706 spin_lock_irq(&cache->lock);
707 r = test_bit(from_dblock(oblock_to_dblock(cache, b)),
708 cache->discard_bitset);
709 spin_unlock_irq(&cache->lock);
710
711 return r;
712}
713
714/*
715 * -------------------------------------------------------------
716 * Remapping
717 *--------------------------------------------------------------
718 */
719static void remap_to_origin(struct cache *cache, struct bio *bio)
720{
721 bio_set_dev(bio, cache->origin_dev->bdev);
722}
723
724static void remap_to_cache(struct cache *cache, struct bio *bio,
725 dm_cblock_t cblock)
726{
727 sector_t bi_sector = bio->bi_iter.bi_sector;
728 sector_t block = from_cblock(cblock);
729
730 bio_set_dev(bio, cache->cache_dev->bdev);
731 if (!block_size_is_power_of_two(cache))
732 bio->bi_iter.bi_sector =
733 (block * cache->sectors_per_block) +
734 sector_div(bi_sector, cache->sectors_per_block);
735 else
736 bio->bi_iter.bi_sector =
737 (block << cache->sectors_per_block_shift) |
738 (bi_sector & (cache->sectors_per_block - 1));
739}
740
741static void check_if_tick_bio_needed(struct cache *cache, struct bio *bio)
742{
743 struct per_bio_data *pb;
744
745 spin_lock_irq(&cache->lock);
746 if (cache->need_tick_bio && !op_is_flush(bio->bi_opf) &&
747 bio_op(bio) != REQ_OP_DISCARD) {
748 pb = get_per_bio_data(bio);
749 pb->tick = true;
750 cache->need_tick_bio = false;
751 }
752 spin_unlock_irq(&cache->lock);
753}
754
755static void remap_to_origin_clear_discard(struct cache *cache, struct bio *bio,
756 dm_oblock_t oblock)
757{
758 // FIXME: check_if_tick_bio_needed() is called way too much through this interface
759 check_if_tick_bio_needed(cache, bio);
760 remap_to_origin(cache, bio);
761 if (bio_data_dir(bio) == WRITE)
762 clear_discard(cache, oblock_to_dblock(cache, oblock));
763}
764
765static void remap_to_cache_dirty(struct cache *cache, struct bio *bio,
766 dm_oblock_t oblock, dm_cblock_t cblock)
767{
768 check_if_tick_bio_needed(cache, bio);
769 remap_to_cache(cache, bio, cblock);
770 if (bio_data_dir(bio) == WRITE) {
771 set_dirty(cache, cblock);
772 clear_discard(cache, oblock_to_dblock(cache, oblock));
773 }
774}
775
776static dm_oblock_t get_bio_block(struct cache *cache, struct bio *bio)
777{
778 sector_t block_nr = bio->bi_iter.bi_sector;
779
780 if (!block_size_is_power_of_two(cache))
781 (void) sector_div(block_nr, cache->sectors_per_block);
782 else
783 block_nr >>= cache->sectors_per_block_shift;
784
785 return to_oblock(block_nr);
786}
787
788static bool accountable_bio(struct cache *cache, struct bio *bio)
789{
790 return bio_op(bio) != REQ_OP_DISCARD;
791}
792
793static void accounted_begin(struct cache *cache, struct bio *bio)
794{
795 struct per_bio_data *pb;
796
797 if (accountable_bio(cache, bio)) {
798 pb = get_per_bio_data(bio);
799 pb->len = bio_sectors(bio);
800 dm_iot_io_begin(&cache->tracker, pb->len);
801 }
802}
803
804static void accounted_complete(struct cache *cache, struct bio *bio)
805{
806 struct per_bio_data *pb = get_per_bio_data(bio);
807
808 dm_iot_io_end(&cache->tracker, pb->len);
809}
810
811static void accounted_request(struct cache *cache, struct bio *bio)
812{
813 accounted_begin(cache, bio);
814 dm_submit_bio_remap(bio, NULL);
815}
816
817static void issue_op(struct bio *bio, void *context)
818{
819 struct cache *cache = context;
820
821 accounted_request(cache, bio);
822}
823
824/*
825 * When running in writethrough mode we need to send writes to clean blocks
826 * to both the cache and origin devices. Clone the bio and send them in parallel.
827 */
828static void remap_to_origin_and_cache(struct cache *cache, struct bio *bio,
829 dm_oblock_t oblock, dm_cblock_t cblock)
830{
831 struct bio *origin_bio = bio_alloc_clone(cache->origin_dev->bdev, bio,
832 GFP_NOIO, &cache->bs);
833
834 BUG_ON(!origin_bio);
835
836 bio_chain(origin_bio, bio);
837
838 if (bio_data_dir(origin_bio) == WRITE)
839 clear_discard(cache, oblock_to_dblock(cache, oblock));
840 submit_bio(origin_bio);
841
842 remap_to_cache(cache, bio, cblock);
843}
844
845/*
846 *--------------------------------------------------------------
847 * Failure modes
848 *--------------------------------------------------------------
849 */
850static enum cache_metadata_mode get_cache_mode(struct cache *cache)
851{
852 return cache->features.mode;
853}
854
855static const char *cache_device_name(struct cache *cache)
856{
857 return dm_table_device_name(cache->ti->table);
858}
859
860static void notify_mode_switch(struct cache *cache, enum cache_metadata_mode mode)
861{
862 static const char *descs[] = {
863 "write",
864 "read-only",
865 "fail"
866 };
867
868 dm_table_event(cache->ti->table);
869 DMINFO("%s: switching cache to %s mode",
870 cache_device_name(cache), descs[(int)mode]);
871}
872
873static void set_cache_mode(struct cache *cache, enum cache_metadata_mode new_mode)
874{
875 bool needs_check;
876 enum cache_metadata_mode old_mode = get_cache_mode(cache);
877
878 if (dm_cache_metadata_needs_check(cache->cmd, &needs_check)) {
879 DMERR("%s: unable to read needs_check flag, setting failure mode.",
880 cache_device_name(cache));
881 new_mode = CM_FAIL;
882 }
883
884 if (new_mode == CM_WRITE && needs_check) {
885 DMERR("%s: unable to switch cache to write mode until repaired.",
886 cache_device_name(cache));
887 if (old_mode != new_mode)
888 new_mode = old_mode;
889 else
890 new_mode = CM_READ_ONLY;
891 }
892
893 /* Never move out of fail mode */
894 if (old_mode == CM_FAIL)
895 new_mode = CM_FAIL;
896
897 switch (new_mode) {
898 case CM_FAIL:
899 case CM_READ_ONLY:
900 dm_cache_metadata_set_read_only(cache->cmd);
901 break;
902
903 case CM_WRITE:
904 dm_cache_metadata_set_read_write(cache->cmd);
905 break;
906 }
907
908 cache->features.mode = new_mode;
909
910 if (new_mode != old_mode)
911 notify_mode_switch(cache, new_mode);
912}
913
914static void abort_transaction(struct cache *cache)
915{
916 const char *dev_name = cache_device_name(cache);
917
918 if (get_cache_mode(cache) >= CM_READ_ONLY)
919 return;
920
921 DMERR_LIMIT("%s: aborting current metadata transaction", dev_name);
922 if (dm_cache_metadata_abort(cache->cmd)) {
923 DMERR("%s: failed to abort metadata transaction", dev_name);
924 set_cache_mode(cache, CM_FAIL);
925 }
926
927 if (dm_cache_metadata_set_needs_check(cache->cmd)) {
928 DMERR("%s: failed to set 'needs_check' flag in metadata", dev_name);
929 set_cache_mode(cache, CM_FAIL);
930 }
931}
932
933static void metadata_operation_failed(struct cache *cache, const char *op, int r)
934{
935 DMERR_LIMIT("%s: metadata operation '%s' failed: error = %d",
936 cache_device_name(cache), op, r);
937 abort_transaction(cache);
938 set_cache_mode(cache, CM_READ_ONLY);
939}
940
941/*----------------------------------------------------------------*/
942
943static void load_stats(struct cache *cache)
944{
945 struct dm_cache_statistics stats;
946
947 dm_cache_metadata_get_stats(cache->cmd, &stats);
948 atomic_set(&cache->stats.read_hit, stats.read_hits);
949 atomic_set(&cache->stats.read_miss, stats.read_misses);
950 atomic_set(&cache->stats.write_hit, stats.write_hits);
951 atomic_set(&cache->stats.write_miss, stats.write_misses);
952}
953
954static void save_stats(struct cache *cache)
955{
956 struct dm_cache_statistics stats;
957
958 if (get_cache_mode(cache) >= CM_READ_ONLY)
959 return;
960
961 stats.read_hits = atomic_read(&cache->stats.read_hit);
962 stats.read_misses = atomic_read(&cache->stats.read_miss);
963 stats.write_hits = atomic_read(&cache->stats.write_hit);
964 stats.write_misses = atomic_read(&cache->stats.write_miss);
965
966 dm_cache_metadata_set_stats(cache->cmd, &stats);
967}
968
969static void update_stats(struct cache_stats *stats, enum policy_operation op)
970{
971 switch (op) {
972 case POLICY_PROMOTE:
973 atomic_inc(&stats->promotion);
974 break;
975
976 case POLICY_DEMOTE:
977 atomic_inc(&stats->demotion);
978 break;
979
980 case POLICY_WRITEBACK:
981 atomic_inc(&stats->writeback);
982 break;
983 }
984}
985
986/*
987 *---------------------------------------------------------------------
988 * Migration processing
989 *
990 * Migration covers moving data from the origin device to the cache, or
991 * vice versa.
992 *---------------------------------------------------------------------
993 */
994static void inc_io_migrations(struct cache *cache)
995{
996 atomic_inc(&cache->nr_io_migrations);
997}
998
999static void dec_io_migrations(struct cache *cache)
1000{
1001 atomic_dec(&cache->nr_io_migrations);
1002}
1003
1004static bool discard_or_flush(struct bio *bio)
1005{
1006 return bio_op(bio) == REQ_OP_DISCARD || op_is_flush(bio->bi_opf);
1007}
1008
1009static void calc_discard_block_range(struct cache *cache, struct bio *bio,
1010 dm_dblock_t *b, dm_dblock_t *e)
1011{
1012 sector_t sb = bio->bi_iter.bi_sector;
1013 sector_t se = bio_end_sector(bio);
1014
1015 *b = to_dblock(dm_sector_div_up(sb, cache->discard_block_size));
1016
1017 if (se - sb < cache->discard_block_size)
1018 *e = *b;
1019 else
1020 *e = to_dblock(block_div(se, cache->discard_block_size));
1021}
1022
1023/*----------------------------------------------------------------*/
1024
1025static void prevent_background_work(struct cache *cache)
1026{
1027 lockdep_off();
1028 down_write(&cache->background_work_lock);
1029 lockdep_on();
1030}
1031
1032static void allow_background_work(struct cache *cache)
1033{
1034 lockdep_off();
1035 up_write(&cache->background_work_lock);
1036 lockdep_on();
1037}
1038
1039static bool background_work_begin(struct cache *cache)
1040{
1041 bool r;
1042
1043 lockdep_off();
1044 r = down_read_trylock(&cache->background_work_lock);
1045 lockdep_on();
1046
1047 return r;
1048}
1049
1050static void background_work_end(struct cache *cache)
1051{
1052 lockdep_off();
1053 up_read(&cache->background_work_lock);
1054 lockdep_on();
1055}
1056
1057/*----------------------------------------------------------------*/
1058
1059static bool bio_writes_complete_block(struct cache *cache, struct bio *bio)
1060{
1061 return (bio_data_dir(bio) == WRITE) &&
1062 (bio->bi_iter.bi_size == (cache->sectors_per_block << SECTOR_SHIFT));
1063}
1064
1065static bool optimisable_bio(struct cache *cache, struct bio *bio, dm_oblock_t block)
1066{
1067 return writeback_mode(cache) &&
1068 (is_discarded_oblock(cache, block) || bio_writes_complete_block(cache, bio));
1069}
1070
1071static void quiesce(struct dm_cache_migration *mg,
1072 void (*continuation)(struct work_struct *))
1073{
1074 init_continuation(&mg->k, continuation);
1075 dm_cell_quiesce_v2(mg->cache->prison, mg->cell, &mg->k.ws);
1076}
1077
1078static struct dm_cache_migration *ws_to_mg(struct work_struct *ws)
1079{
1080 struct continuation *k = container_of(ws, struct continuation, ws);
1081
1082 return container_of(k, struct dm_cache_migration, k);
1083}
1084
1085static void copy_complete(int read_err, unsigned long write_err, void *context)
1086{
1087 struct dm_cache_migration *mg = container_of(context, struct dm_cache_migration, k);
1088
1089 if (read_err || write_err)
1090 mg->k.input = BLK_STS_IOERR;
1091
1092 queue_continuation(mg->cache->wq, &mg->k);
1093}
1094
1095static void copy(struct dm_cache_migration *mg, bool promote)
1096{
1097 struct dm_io_region o_region, c_region;
1098 struct cache *cache = mg->cache;
1099
1100 o_region.bdev = cache->origin_dev->bdev;
1101 o_region.sector = from_oblock(mg->op->oblock) * cache->sectors_per_block;
1102 o_region.count = cache->sectors_per_block;
1103
1104 c_region.bdev = cache->cache_dev->bdev;
1105 c_region.sector = from_cblock(mg->op->cblock) * cache->sectors_per_block;
1106 c_region.count = cache->sectors_per_block;
1107
1108 if (promote)
1109 dm_kcopyd_copy(cache->copier, &o_region, 1, &c_region, 0, copy_complete, &mg->k);
1110 else
1111 dm_kcopyd_copy(cache->copier, &c_region, 1, &o_region, 0, copy_complete, &mg->k);
1112}
1113
1114static void bio_drop_shared_lock(struct cache *cache, struct bio *bio)
1115{
1116 struct per_bio_data *pb = get_per_bio_data(bio);
1117
1118 if (pb->cell && dm_cell_put_v2(cache->prison, pb->cell))
1119 free_prison_cell(cache, pb->cell);
1120 pb->cell = NULL;
1121}
1122
1123static void overwrite_endio(struct bio *bio)
1124{
1125 struct dm_cache_migration *mg = bio->bi_private;
1126 struct cache *cache = mg->cache;
1127 struct per_bio_data *pb = get_per_bio_data(bio);
1128
1129 dm_unhook_bio(&pb->hook_info, bio);
1130
1131 if (bio->bi_status)
1132 mg->k.input = bio->bi_status;
1133
1134 queue_continuation(cache->wq, &mg->k);
1135}
1136
1137static void overwrite(struct dm_cache_migration *mg,
1138 void (*continuation)(struct work_struct *))
1139{
1140 struct bio *bio = mg->overwrite_bio;
1141 struct per_bio_data *pb = get_per_bio_data(bio);
1142
1143 dm_hook_bio(&pb->hook_info, bio, overwrite_endio, mg);
1144
1145 /*
1146 * The overwrite bio is part of the copy operation, as such it does
1147 * not set/clear discard or dirty flags.
1148 */
1149 if (mg->op->op == POLICY_PROMOTE)
1150 remap_to_cache(mg->cache, bio, mg->op->cblock);
1151 else
1152 remap_to_origin(mg->cache, bio);
1153
1154 init_continuation(&mg->k, continuation);
1155 accounted_request(mg->cache, bio);
1156}
1157
1158/*
1159 * Migration steps:
1160 *
1161 * 1) exclusive lock preventing WRITEs
1162 * 2) quiesce
1163 * 3) copy or issue overwrite bio
1164 * 4) upgrade to exclusive lock preventing READs and WRITEs
1165 * 5) quiesce
1166 * 6) update metadata and commit
1167 * 7) unlock
1168 */
1169static void mg_complete(struct dm_cache_migration *mg, bool success)
1170{
1171 struct bio_list bios;
1172 struct cache *cache = mg->cache;
1173 struct policy_work *op = mg->op;
1174 dm_cblock_t cblock = op->cblock;
1175
1176 if (success)
1177 update_stats(&cache->stats, op->op);
1178
1179 switch (op->op) {
1180 case POLICY_PROMOTE:
1181 clear_discard(cache, oblock_to_dblock(cache, op->oblock));
1182 policy_complete_background_work(cache->policy, op, success);
1183
1184 if (mg->overwrite_bio) {
1185 if (success)
1186 force_set_dirty(cache, cblock);
1187 else if (mg->k.input)
1188 mg->overwrite_bio->bi_status = mg->k.input;
1189 else
1190 mg->overwrite_bio->bi_status = BLK_STS_IOERR;
1191 bio_endio(mg->overwrite_bio);
1192 } else {
1193 if (success)
1194 force_clear_dirty(cache, cblock);
1195 dec_io_migrations(cache);
1196 }
1197 break;
1198
1199 case POLICY_DEMOTE:
1200 /*
1201 * We clear dirty here to update the nr_dirty counter.
1202 */
1203 if (success)
1204 force_clear_dirty(cache, cblock);
1205 policy_complete_background_work(cache->policy, op, success);
1206 dec_io_migrations(cache);
1207 break;
1208
1209 case POLICY_WRITEBACK:
1210 if (success)
1211 force_clear_dirty(cache, cblock);
1212 policy_complete_background_work(cache->policy, op, success);
1213 dec_io_migrations(cache);
1214 break;
1215 }
1216
1217 bio_list_init(&bios);
1218 if (mg->cell) {
1219 if (dm_cell_unlock_v2(cache->prison, mg->cell, &bios))
1220 free_prison_cell(cache, mg->cell);
1221 }
1222
1223 free_migration(mg);
1224 defer_bios(cache, &bios);
1225 wake_migration_worker(cache);
1226
1227 background_work_end(cache);
1228}
1229
1230static void mg_success(struct work_struct *ws)
1231{
1232 struct dm_cache_migration *mg = ws_to_mg(ws);
1233
1234 mg_complete(mg, mg->k.input == 0);
1235}
1236
1237static void mg_update_metadata(struct work_struct *ws)
1238{
1239 int r;
1240 struct dm_cache_migration *mg = ws_to_mg(ws);
1241 struct cache *cache = mg->cache;
1242 struct policy_work *op = mg->op;
1243
1244 switch (op->op) {
1245 case POLICY_PROMOTE:
1246 r = dm_cache_insert_mapping(cache->cmd, op->cblock, op->oblock);
1247 if (r) {
1248 DMERR_LIMIT("%s: migration failed; couldn't insert mapping",
1249 cache_device_name(cache));
1250 metadata_operation_failed(cache, "dm_cache_insert_mapping", r);
1251
1252 mg_complete(mg, false);
1253 return;
1254 }
1255 mg_complete(mg, true);
1256 break;
1257
1258 case POLICY_DEMOTE:
1259 r = dm_cache_remove_mapping(cache->cmd, op->cblock);
1260 if (r) {
1261 DMERR_LIMIT("%s: migration failed; couldn't update on disk metadata",
1262 cache_device_name(cache));
1263 metadata_operation_failed(cache, "dm_cache_remove_mapping", r);
1264
1265 mg_complete(mg, false);
1266 return;
1267 }
1268
1269 /*
1270 * It would be nice if we only had to commit when a REQ_FLUSH
1271 * comes through. But there's one scenario that we have to
1272 * look out for:
1273 *
1274 * - vblock x in a cache block
1275 * - domotion occurs
1276 * - cache block gets reallocated and over written
1277 * - crash
1278 *
1279 * When we recover, because there was no commit the cache will
1280 * rollback to having the data for vblock x in the cache block.
1281 * But the cache block has since been overwritten, so it'll end
1282 * up pointing to data that was never in 'x' during the history
1283 * of the device.
1284 *
1285 * To avoid this issue we require a commit as part of the
1286 * demotion operation.
1287 */
1288 init_continuation(&mg->k, mg_success);
1289 continue_after_commit(&cache->committer, &mg->k);
1290 schedule_commit(&cache->committer);
1291 break;
1292
1293 case POLICY_WRITEBACK:
1294 mg_complete(mg, true);
1295 break;
1296 }
1297}
1298
1299static void mg_update_metadata_after_copy(struct work_struct *ws)
1300{
1301 struct dm_cache_migration *mg = ws_to_mg(ws);
1302
1303 /*
1304 * Did the copy succeed?
1305 */
1306 if (mg->k.input)
1307 mg_complete(mg, false);
1308 else
1309 mg_update_metadata(ws);
1310}
1311
1312static void mg_upgrade_lock(struct work_struct *ws)
1313{
1314 int r;
1315 struct dm_cache_migration *mg = ws_to_mg(ws);
1316
1317 /*
1318 * Did the copy succeed?
1319 */
1320 if (mg->k.input)
1321 mg_complete(mg, false);
1322
1323 else {
1324 /*
1325 * Now we want the lock to prevent both reads and writes.
1326 */
1327 r = dm_cell_lock_promote_v2(mg->cache->prison, mg->cell,
1328 READ_WRITE_LOCK_LEVEL);
1329 if (r < 0)
1330 mg_complete(mg, false);
1331
1332 else if (r)
1333 quiesce(mg, mg_update_metadata);
1334
1335 else
1336 mg_update_metadata(ws);
1337 }
1338}
1339
1340static void mg_full_copy(struct work_struct *ws)
1341{
1342 struct dm_cache_migration *mg = ws_to_mg(ws);
1343 struct cache *cache = mg->cache;
1344 struct policy_work *op = mg->op;
1345 bool is_policy_promote = (op->op == POLICY_PROMOTE);
1346
1347 if ((!is_policy_promote && !is_dirty(cache, op->cblock)) ||
1348 is_discarded_oblock(cache, op->oblock)) {
1349 mg_upgrade_lock(ws);
1350 return;
1351 }
1352
1353 init_continuation(&mg->k, mg_upgrade_lock);
1354 copy(mg, is_policy_promote);
1355}
1356
1357static void mg_copy(struct work_struct *ws)
1358{
1359 struct dm_cache_migration *mg = ws_to_mg(ws);
1360
1361 if (mg->overwrite_bio) {
1362 /*
1363 * No exclusive lock was held when we last checked if the bio
1364 * was optimisable. So we have to check again in case things
1365 * have changed (eg, the block may no longer be discarded).
1366 */
1367 if (!optimisable_bio(mg->cache, mg->overwrite_bio, mg->op->oblock)) {
1368 /*
1369 * Fallback to a real full copy after doing some tidying up.
1370 */
1371 bool rb = bio_detain_shared(mg->cache, mg->op->oblock, mg->overwrite_bio);
1372
1373 BUG_ON(rb); /* An exclussive lock must _not_ be held for this block */
1374 mg->overwrite_bio = NULL;
1375 inc_io_migrations(mg->cache);
1376 mg_full_copy(ws);
1377 return;
1378 }
1379
1380 /*
1381 * It's safe to do this here, even though it's new data
1382 * because all IO has been locked out of the block.
1383 *
1384 * mg_lock_writes() already took READ_WRITE_LOCK_LEVEL
1385 * so _not_ using mg_upgrade_lock() as continutation.
1386 */
1387 overwrite(mg, mg_update_metadata_after_copy);
1388
1389 } else
1390 mg_full_copy(ws);
1391}
1392
1393static int mg_lock_writes(struct dm_cache_migration *mg)
1394{
1395 int r;
1396 struct dm_cell_key_v2 key;
1397 struct cache *cache = mg->cache;
1398 struct dm_bio_prison_cell_v2 *prealloc;
1399
1400 prealloc = alloc_prison_cell(cache);
1401
1402 /*
1403 * Prevent writes to the block, but allow reads to continue.
1404 * Unless we're using an overwrite bio, in which case we lock
1405 * everything.
1406 */
1407 build_key(mg->op->oblock, oblock_succ(mg->op->oblock), &key);
1408 r = dm_cell_lock_v2(cache->prison, &key,
1409 mg->overwrite_bio ? READ_WRITE_LOCK_LEVEL : WRITE_LOCK_LEVEL,
1410 prealloc, &mg->cell);
1411 if (r < 0) {
1412 free_prison_cell(cache, prealloc);
1413 mg_complete(mg, false);
1414 return r;
1415 }
1416
1417 if (mg->cell != prealloc)
1418 free_prison_cell(cache, prealloc);
1419
1420 if (r == 0)
1421 mg_copy(&mg->k.ws);
1422 else
1423 quiesce(mg, mg_copy);
1424
1425 return 0;
1426}
1427
1428static int mg_start(struct cache *cache, struct policy_work *op, struct bio *bio)
1429{
1430 struct dm_cache_migration *mg;
1431
1432 if (!background_work_begin(cache)) {
1433 policy_complete_background_work(cache->policy, op, false);
1434 return -EPERM;
1435 }
1436
1437 mg = alloc_migration(cache);
1438
1439 mg->op = op;
1440 mg->overwrite_bio = bio;
1441
1442 if (!bio)
1443 inc_io_migrations(cache);
1444
1445 return mg_lock_writes(mg);
1446}
1447
1448/*
1449 *--------------------------------------------------------------
1450 * invalidation processing
1451 *--------------------------------------------------------------
1452 */
1453
1454static void invalidate_complete(struct dm_cache_migration *mg, bool success)
1455{
1456 struct bio_list bios;
1457 struct cache *cache = mg->cache;
1458
1459 bio_list_init(&bios);
1460 if (dm_cell_unlock_v2(cache->prison, mg->cell, &bios))
1461 free_prison_cell(cache, mg->cell);
1462
1463 if (!success && mg->overwrite_bio)
1464 bio_io_error(mg->overwrite_bio);
1465
1466 free_migration(mg);
1467 defer_bios(cache, &bios);
1468
1469 background_work_end(cache);
1470}
1471
1472static void invalidate_completed(struct work_struct *ws)
1473{
1474 struct dm_cache_migration *mg = ws_to_mg(ws);
1475
1476 invalidate_complete(mg, !mg->k.input);
1477}
1478
1479static int invalidate_cblock(struct cache *cache, dm_cblock_t cblock)
1480{
1481 int r;
1482
1483 r = policy_invalidate_mapping(cache->policy, cblock);
1484 if (!r) {
1485 r = dm_cache_remove_mapping(cache->cmd, cblock);
1486 if (r) {
1487 DMERR_LIMIT("%s: invalidation failed; couldn't update on disk metadata",
1488 cache_device_name(cache));
1489 metadata_operation_failed(cache, "dm_cache_remove_mapping", r);
1490 }
1491
1492 } else if (r == -ENODATA) {
1493 /*
1494 * Harmless, already unmapped.
1495 */
1496 r = 0;
1497
1498 } else
1499 DMERR("%s: policy_invalidate_mapping failed", cache_device_name(cache));
1500
1501 return r;
1502}
1503
1504static void invalidate_remove(struct work_struct *ws)
1505{
1506 int r;
1507 struct dm_cache_migration *mg = ws_to_mg(ws);
1508 struct cache *cache = mg->cache;
1509
1510 r = invalidate_cblock(cache, mg->invalidate_cblock);
1511 if (r) {
1512 invalidate_complete(mg, false);
1513 return;
1514 }
1515
1516 init_continuation(&mg->k, invalidate_completed);
1517 continue_after_commit(&cache->committer, &mg->k);
1518 remap_to_origin_clear_discard(cache, mg->overwrite_bio, mg->invalidate_oblock);
1519 mg->overwrite_bio = NULL;
1520 schedule_commit(&cache->committer);
1521}
1522
1523static int invalidate_lock(struct dm_cache_migration *mg)
1524{
1525 int r;
1526 struct dm_cell_key_v2 key;
1527 struct cache *cache = mg->cache;
1528 struct dm_bio_prison_cell_v2 *prealloc;
1529
1530 prealloc = alloc_prison_cell(cache);
1531
1532 build_key(mg->invalidate_oblock, oblock_succ(mg->invalidate_oblock), &key);
1533 r = dm_cell_lock_v2(cache->prison, &key,
1534 READ_WRITE_LOCK_LEVEL, prealloc, &mg->cell);
1535 if (r < 0) {
1536 free_prison_cell(cache, prealloc);
1537 invalidate_complete(mg, false);
1538 return r;
1539 }
1540
1541 if (mg->cell != prealloc)
1542 free_prison_cell(cache, prealloc);
1543
1544 if (r)
1545 quiesce(mg, invalidate_remove);
1546
1547 else {
1548 /*
1549 * We can't call invalidate_remove() directly here because we
1550 * might still be in request context.
1551 */
1552 init_continuation(&mg->k, invalidate_remove);
1553 queue_work(cache->wq, &mg->k.ws);
1554 }
1555
1556 return 0;
1557}
1558
1559static int invalidate_start(struct cache *cache, dm_cblock_t cblock,
1560 dm_oblock_t oblock, struct bio *bio)
1561{
1562 struct dm_cache_migration *mg;
1563
1564 if (!background_work_begin(cache))
1565 return -EPERM;
1566
1567 mg = alloc_migration(cache);
1568
1569 mg->overwrite_bio = bio;
1570 mg->invalidate_cblock = cblock;
1571 mg->invalidate_oblock = oblock;
1572
1573 return invalidate_lock(mg);
1574}
1575
1576/*
1577 *--------------------------------------------------------------
1578 * bio processing
1579 *--------------------------------------------------------------
1580 */
1581
1582enum busy {
1583 IDLE,
1584 BUSY
1585};
1586
1587static enum busy spare_migration_bandwidth(struct cache *cache)
1588{
1589 bool idle = dm_iot_idle_for(&cache->tracker, HZ);
1590 sector_t current_volume = (atomic_read(&cache->nr_io_migrations) + 1) *
1591 cache->sectors_per_block;
1592
1593 if (idle && current_volume <= cache->migration_threshold)
1594 return IDLE;
1595 else
1596 return BUSY;
1597}
1598
1599static void inc_hit_counter(struct cache *cache, struct bio *bio)
1600{
1601 atomic_inc(bio_data_dir(bio) == READ ?
1602 &cache->stats.read_hit : &cache->stats.write_hit);
1603}
1604
1605static void inc_miss_counter(struct cache *cache, struct bio *bio)
1606{
1607 atomic_inc(bio_data_dir(bio) == READ ?
1608 &cache->stats.read_miss : &cache->stats.write_miss);
1609}
1610
1611/*----------------------------------------------------------------*/
1612
1613static int map_bio(struct cache *cache, struct bio *bio, dm_oblock_t block,
1614 bool *commit_needed)
1615{
1616 int r, data_dir;
1617 bool rb, background_queued;
1618 dm_cblock_t cblock;
1619
1620 *commit_needed = false;
1621
1622 rb = bio_detain_shared(cache, block, bio);
1623 if (!rb) {
1624 /*
1625 * An exclusive lock is held for this block, so we have to
1626 * wait. We set the commit_needed flag so the current
1627 * transaction will be committed asap, allowing this lock
1628 * to be dropped.
1629 */
1630 *commit_needed = true;
1631 return DM_MAPIO_SUBMITTED;
1632 }
1633
1634 data_dir = bio_data_dir(bio);
1635
1636 if (optimisable_bio(cache, bio, block)) {
1637 struct policy_work *op = NULL;
1638
1639 r = policy_lookup_with_work(cache->policy, block, &cblock, data_dir, true, &op);
1640 if (unlikely(r && r != -ENOENT)) {
1641 DMERR_LIMIT("%s: policy_lookup_with_work() failed with r = %d",
1642 cache_device_name(cache), r);
1643 bio_io_error(bio);
1644 return DM_MAPIO_SUBMITTED;
1645 }
1646
1647 if (r == -ENOENT && op) {
1648 bio_drop_shared_lock(cache, bio);
1649 BUG_ON(op->op != POLICY_PROMOTE);
1650 mg_start(cache, op, bio);
1651 return DM_MAPIO_SUBMITTED;
1652 }
1653 } else {
1654 r = policy_lookup(cache->policy, block, &cblock, data_dir, false, &background_queued);
1655 if (unlikely(r && r != -ENOENT)) {
1656 DMERR_LIMIT("%s: policy_lookup() failed with r = %d",
1657 cache_device_name(cache), r);
1658 bio_io_error(bio);
1659 return DM_MAPIO_SUBMITTED;
1660 }
1661
1662 if (background_queued)
1663 wake_migration_worker(cache);
1664 }
1665
1666 if (r == -ENOENT) {
1667 struct per_bio_data *pb = get_per_bio_data(bio);
1668
1669 /*
1670 * Miss.
1671 */
1672 inc_miss_counter(cache, bio);
1673 if (pb->req_nr == 0) {
1674 accounted_begin(cache, bio);
1675 remap_to_origin_clear_discard(cache, bio, block);
1676 } else {
1677 /*
1678 * This is a duplicate writethrough io that is no
1679 * longer needed because the block has been demoted.
1680 */
1681 bio_endio(bio);
1682 return DM_MAPIO_SUBMITTED;
1683 }
1684 } else {
1685 /*
1686 * Hit.
1687 */
1688 inc_hit_counter(cache, bio);
1689
1690 /*
1691 * Passthrough always maps to the origin, invalidating any
1692 * cache blocks that are written to.
1693 */
1694 if (passthrough_mode(cache)) {
1695 if (bio_data_dir(bio) == WRITE) {
1696 bio_drop_shared_lock(cache, bio);
1697 atomic_inc(&cache->stats.demotion);
1698 invalidate_start(cache, cblock, block, bio);
1699 } else
1700 remap_to_origin_clear_discard(cache, bio, block);
1701 } else {
1702 if (bio_data_dir(bio) == WRITE && writethrough_mode(cache) &&
1703 !is_dirty(cache, cblock)) {
1704 remap_to_origin_and_cache(cache, bio, block, cblock);
1705 accounted_begin(cache, bio);
1706 } else
1707 remap_to_cache_dirty(cache, bio, block, cblock);
1708 }
1709 }
1710
1711 /*
1712 * dm core turns FUA requests into a separate payload and FLUSH req.
1713 */
1714 if (bio->bi_opf & REQ_FUA) {
1715 /*
1716 * issue_after_commit will call accounted_begin a second time. So
1717 * we call accounted_complete() to avoid double accounting.
1718 */
1719 accounted_complete(cache, bio);
1720 issue_after_commit(&cache->committer, bio);
1721 *commit_needed = true;
1722 return DM_MAPIO_SUBMITTED;
1723 }
1724
1725 return DM_MAPIO_REMAPPED;
1726}
1727
1728static bool process_bio(struct cache *cache, struct bio *bio)
1729{
1730 bool commit_needed;
1731
1732 if (map_bio(cache, bio, get_bio_block(cache, bio), &commit_needed) == DM_MAPIO_REMAPPED)
1733 dm_submit_bio_remap(bio, NULL);
1734
1735 return commit_needed;
1736}
1737
1738/*
1739 * A non-zero return indicates read_only or fail_io mode.
1740 */
1741static int commit(struct cache *cache, bool clean_shutdown)
1742{
1743 int r;
1744
1745 if (get_cache_mode(cache) >= CM_READ_ONLY)
1746 return -EINVAL;
1747
1748 atomic_inc(&cache->stats.commit_count);
1749 r = dm_cache_commit(cache->cmd, clean_shutdown);
1750 if (r)
1751 metadata_operation_failed(cache, "dm_cache_commit", r);
1752
1753 return r;
1754}
1755
1756/*
1757 * Used by the batcher.
1758 */
1759static blk_status_t commit_op(void *context)
1760{
1761 struct cache *cache = context;
1762
1763 if (dm_cache_changed_this_transaction(cache->cmd))
1764 return errno_to_blk_status(commit(cache, false));
1765
1766 return 0;
1767}
1768
1769/*----------------------------------------------------------------*/
1770
1771static bool process_flush_bio(struct cache *cache, struct bio *bio)
1772{
1773 struct per_bio_data *pb = get_per_bio_data(bio);
1774
1775 if (!pb->req_nr)
1776 remap_to_origin(cache, bio);
1777 else
1778 remap_to_cache(cache, bio, 0);
1779
1780 issue_after_commit(&cache->committer, bio);
1781 return true;
1782}
1783
1784static bool process_discard_bio(struct cache *cache, struct bio *bio)
1785{
1786 dm_dblock_t b, e;
1787
1788 /*
1789 * FIXME: do we need to lock the region? Or can we just assume the
1790 * user wont be so foolish as to issue discard concurrently with
1791 * other IO?
1792 */
1793 calc_discard_block_range(cache, bio, &b, &e);
1794 while (b != e) {
1795 set_discard(cache, b);
1796 b = to_dblock(from_dblock(b) + 1);
1797 }
1798
1799 if (cache->features.discard_passdown) {
1800 remap_to_origin(cache, bio);
1801 dm_submit_bio_remap(bio, NULL);
1802 } else
1803 bio_endio(bio);
1804
1805 return false;
1806}
1807
1808static void process_deferred_bios(struct work_struct *ws)
1809{
1810 struct cache *cache = container_of(ws, struct cache, deferred_bio_worker);
1811
1812 bool commit_needed = false;
1813 struct bio_list bios;
1814 struct bio *bio;
1815
1816 bio_list_init(&bios);
1817
1818 spin_lock_irq(&cache->lock);
1819 bio_list_merge(&bios, &cache->deferred_bios);
1820 bio_list_init(&cache->deferred_bios);
1821 spin_unlock_irq(&cache->lock);
1822
1823 while ((bio = bio_list_pop(&bios))) {
1824 if (bio->bi_opf & REQ_PREFLUSH)
1825 commit_needed = process_flush_bio(cache, bio) || commit_needed;
1826
1827 else if (bio_op(bio) == REQ_OP_DISCARD)
1828 commit_needed = process_discard_bio(cache, bio) || commit_needed;
1829
1830 else
1831 commit_needed = process_bio(cache, bio) || commit_needed;
1832 cond_resched();
1833 }
1834
1835 if (commit_needed)
1836 schedule_commit(&cache->committer);
1837}
1838
1839/*
1840 *--------------------------------------------------------------
1841 * Main worker loop
1842 *--------------------------------------------------------------
1843 */
1844static void requeue_deferred_bios(struct cache *cache)
1845{
1846 struct bio *bio;
1847 struct bio_list bios;
1848
1849 bio_list_init(&bios);
1850 bio_list_merge(&bios, &cache->deferred_bios);
1851 bio_list_init(&cache->deferred_bios);
1852
1853 while ((bio = bio_list_pop(&bios))) {
1854 bio->bi_status = BLK_STS_DM_REQUEUE;
1855 bio_endio(bio);
1856 cond_resched();
1857 }
1858}
1859
1860/*
1861 * We want to commit periodically so that not too much
1862 * unwritten metadata builds up.
1863 */
1864static void do_waker(struct work_struct *ws)
1865{
1866 struct cache *cache = container_of(to_delayed_work(ws), struct cache, waker);
1867
1868 policy_tick(cache->policy, true);
1869 wake_migration_worker(cache);
1870 schedule_commit(&cache->committer);
1871 queue_delayed_work(cache->wq, &cache->waker, COMMIT_PERIOD);
1872}
1873
1874static void check_migrations(struct work_struct *ws)
1875{
1876 int r;
1877 struct policy_work *op;
1878 struct cache *cache = container_of(ws, struct cache, migration_worker);
1879 enum busy b;
1880
1881 for (;;) {
1882 b = spare_migration_bandwidth(cache);
1883
1884 r = policy_get_background_work(cache->policy, b == IDLE, &op);
1885 if (r == -ENODATA)
1886 break;
1887
1888 if (r) {
1889 DMERR_LIMIT("%s: policy_background_work failed",
1890 cache_device_name(cache));
1891 break;
1892 }
1893
1894 r = mg_start(cache, op, NULL);
1895 if (r)
1896 break;
1897
1898 cond_resched();
1899 }
1900}
1901
1902/*
1903 *--------------------------------------------------------------
1904 * Target methods
1905 *--------------------------------------------------------------
1906 */
1907
1908/*
1909 * This function gets called on the error paths of the constructor, so we
1910 * have to cope with a partially initialised struct.
1911 */
1912static void destroy(struct cache *cache)
1913{
1914 unsigned int i;
1915
1916 mempool_exit(&cache->migration_pool);
1917
1918 if (cache->prison)
1919 dm_bio_prison_destroy_v2(cache->prison);
1920
1921 cancel_delayed_work_sync(&cache->waker);
1922 if (cache->wq)
1923 destroy_workqueue(cache->wq);
1924
1925 if (cache->dirty_bitset)
1926 free_bitset(cache->dirty_bitset);
1927
1928 if (cache->discard_bitset)
1929 free_bitset(cache->discard_bitset);
1930
1931 if (cache->copier)
1932 dm_kcopyd_client_destroy(cache->copier);
1933
1934 if (cache->cmd)
1935 dm_cache_metadata_close(cache->cmd);
1936
1937 if (cache->metadata_dev)
1938 dm_put_device(cache->ti, cache->metadata_dev);
1939
1940 if (cache->origin_dev)
1941 dm_put_device(cache->ti, cache->origin_dev);
1942
1943 if (cache->cache_dev)
1944 dm_put_device(cache->ti, cache->cache_dev);
1945
1946 if (cache->policy)
1947 dm_cache_policy_destroy(cache->policy);
1948
1949 for (i = 0; i < cache->nr_ctr_args ; i++)
1950 kfree(cache->ctr_args[i]);
1951 kfree(cache->ctr_args);
1952
1953 bioset_exit(&cache->bs);
1954
1955 kfree(cache);
1956}
1957
1958static void cache_dtr(struct dm_target *ti)
1959{
1960 struct cache *cache = ti->private;
1961
1962 destroy(cache);
1963}
1964
1965static sector_t get_dev_size(struct dm_dev *dev)
1966{
1967 return bdev_nr_sectors(dev->bdev);
1968}
1969
1970/*----------------------------------------------------------------*/
1971
1972/*
1973 * Construct a cache device mapping.
1974 *
1975 * cache <metadata dev> <cache dev> <origin dev> <block size>
1976 * <#feature args> [<feature arg>]*
1977 * <policy> <#policy args> [<policy arg>]*
1978 *
1979 * metadata dev : fast device holding the persistent metadata
1980 * cache dev : fast device holding cached data blocks
1981 * origin dev : slow device holding original data blocks
1982 * block size : cache unit size in sectors
1983 *
1984 * #feature args : number of feature arguments passed
1985 * feature args : writethrough. (The default is writeback.)
1986 *
1987 * policy : the replacement policy to use
1988 * #policy args : an even number of policy arguments corresponding
1989 * to key/value pairs passed to the policy
1990 * policy args : key/value pairs passed to the policy
1991 * E.g. 'sequential_threshold 1024'
1992 * See cache-policies.txt for details.
1993 *
1994 * Optional feature arguments are:
1995 * writethrough : write through caching that prohibits cache block
1996 * content from being different from origin block content.
1997 * Without this argument, the default behaviour is to write
1998 * back cache block contents later for performance reasons,
1999 * so they may differ from the corresponding origin blocks.
2000 */
2001struct cache_args {
2002 struct dm_target *ti;
2003
2004 struct dm_dev *metadata_dev;
2005
2006 struct dm_dev *cache_dev;
2007 sector_t cache_sectors;
2008
2009 struct dm_dev *origin_dev;
2010 sector_t origin_sectors;
2011
2012 uint32_t block_size;
2013
2014 const char *policy_name;
2015 int policy_argc;
2016 const char **policy_argv;
2017
2018 struct cache_features features;
2019};
2020
2021static void destroy_cache_args(struct cache_args *ca)
2022{
2023 if (ca->metadata_dev)
2024 dm_put_device(ca->ti, ca->metadata_dev);
2025
2026 if (ca->cache_dev)
2027 dm_put_device(ca->ti, ca->cache_dev);
2028
2029 if (ca->origin_dev)
2030 dm_put_device(ca->ti, ca->origin_dev);
2031
2032 kfree(ca);
2033}
2034
2035static bool at_least_one_arg(struct dm_arg_set *as, char **error)
2036{
2037 if (!as->argc) {
2038 *error = "Insufficient args";
2039 return false;
2040 }
2041
2042 return true;
2043}
2044
2045static int parse_metadata_dev(struct cache_args *ca, struct dm_arg_set *as,
2046 char **error)
2047{
2048 int r;
2049 sector_t metadata_dev_size;
2050
2051 if (!at_least_one_arg(as, error))
2052 return -EINVAL;
2053
2054 r = dm_get_device(ca->ti, dm_shift_arg(as),
2055 BLK_OPEN_READ | BLK_OPEN_WRITE, &ca->metadata_dev);
2056 if (r) {
2057 *error = "Error opening metadata device";
2058 return r;
2059 }
2060
2061 metadata_dev_size = get_dev_size(ca->metadata_dev);
2062 if (metadata_dev_size > DM_CACHE_METADATA_MAX_SECTORS_WARNING)
2063 DMWARN("Metadata device %pg is larger than %u sectors: excess space will not be used.",
2064 ca->metadata_dev->bdev, THIN_METADATA_MAX_SECTORS);
2065
2066 return 0;
2067}
2068
2069static int parse_cache_dev(struct cache_args *ca, struct dm_arg_set *as,
2070 char **error)
2071{
2072 int r;
2073
2074 if (!at_least_one_arg(as, error))
2075 return -EINVAL;
2076
2077 r = dm_get_device(ca->ti, dm_shift_arg(as),
2078 BLK_OPEN_READ | BLK_OPEN_WRITE, &ca->cache_dev);
2079 if (r) {
2080 *error = "Error opening cache device";
2081 return r;
2082 }
2083 ca->cache_sectors = get_dev_size(ca->cache_dev);
2084
2085 return 0;
2086}
2087
2088static int parse_origin_dev(struct cache_args *ca, struct dm_arg_set *as,
2089 char **error)
2090{
2091 int r;
2092
2093 if (!at_least_one_arg(as, error))
2094 return -EINVAL;
2095
2096 r = dm_get_device(ca->ti, dm_shift_arg(as),
2097 BLK_OPEN_READ | BLK_OPEN_WRITE, &ca->origin_dev);
2098 if (r) {
2099 *error = "Error opening origin device";
2100 return r;
2101 }
2102
2103 ca->origin_sectors = get_dev_size(ca->origin_dev);
2104 if (ca->ti->len > ca->origin_sectors) {
2105 *error = "Device size larger than cached device";
2106 return -EINVAL;
2107 }
2108
2109 return 0;
2110}
2111
2112static int parse_block_size(struct cache_args *ca, struct dm_arg_set *as,
2113 char **error)
2114{
2115 unsigned long block_size;
2116
2117 if (!at_least_one_arg(as, error))
2118 return -EINVAL;
2119
2120 if (kstrtoul(dm_shift_arg(as), 10, &block_size) || !block_size ||
2121 block_size < DATA_DEV_BLOCK_SIZE_MIN_SECTORS ||
2122 block_size > DATA_DEV_BLOCK_SIZE_MAX_SECTORS ||
2123 block_size & (DATA_DEV_BLOCK_SIZE_MIN_SECTORS - 1)) {
2124 *error = "Invalid data block size";
2125 return -EINVAL;
2126 }
2127
2128 if (block_size > ca->cache_sectors) {
2129 *error = "Data block size is larger than the cache device";
2130 return -EINVAL;
2131 }
2132
2133 ca->block_size = block_size;
2134
2135 return 0;
2136}
2137
2138static void init_features(struct cache_features *cf)
2139{
2140 cf->mode = CM_WRITE;
2141 cf->io_mode = CM_IO_WRITEBACK;
2142 cf->metadata_version = 1;
2143 cf->discard_passdown = true;
2144}
2145
2146static int parse_features(struct cache_args *ca, struct dm_arg_set *as,
2147 char **error)
2148{
2149 static const struct dm_arg _args[] = {
2150 {0, 3, "Invalid number of cache feature arguments"},
2151 };
2152
2153 int r, mode_ctr = 0;
2154 unsigned int argc;
2155 const char *arg;
2156 struct cache_features *cf = &ca->features;
2157
2158 init_features(cf);
2159
2160 r = dm_read_arg_group(_args, as, &argc, error);
2161 if (r)
2162 return -EINVAL;
2163
2164 while (argc--) {
2165 arg = dm_shift_arg(as);
2166
2167 if (!strcasecmp(arg, "writeback")) {
2168 cf->io_mode = CM_IO_WRITEBACK;
2169 mode_ctr++;
2170 }
2171
2172 else if (!strcasecmp(arg, "writethrough")) {
2173 cf->io_mode = CM_IO_WRITETHROUGH;
2174 mode_ctr++;
2175 }
2176
2177 else if (!strcasecmp(arg, "passthrough")) {
2178 cf->io_mode = CM_IO_PASSTHROUGH;
2179 mode_ctr++;
2180 }
2181
2182 else if (!strcasecmp(arg, "metadata2"))
2183 cf->metadata_version = 2;
2184
2185 else if (!strcasecmp(arg, "no_discard_passdown"))
2186 cf->discard_passdown = false;
2187
2188 else {
2189 *error = "Unrecognised cache feature requested";
2190 return -EINVAL;
2191 }
2192 }
2193
2194 if (mode_ctr > 1) {
2195 *error = "Duplicate cache io_mode features requested";
2196 return -EINVAL;
2197 }
2198
2199 return 0;
2200}
2201
2202static int parse_policy(struct cache_args *ca, struct dm_arg_set *as,
2203 char **error)
2204{
2205 static const struct dm_arg _args[] = {
2206 {0, 1024, "Invalid number of policy arguments"},
2207 };
2208
2209 int r;
2210
2211 if (!at_least_one_arg(as, error))
2212 return -EINVAL;
2213
2214 ca->policy_name = dm_shift_arg(as);
2215
2216 r = dm_read_arg_group(_args, as, &ca->policy_argc, error);
2217 if (r)
2218 return -EINVAL;
2219
2220 ca->policy_argv = (const char **)as->argv;
2221 dm_consume_args(as, ca->policy_argc);
2222
2223 return 0;
2224}
2225
2226static int parse_cache_args(struct cache_args *ca, int argc, char **argv,
2227 char **error)
2228{
2229 int r;
2230 struct dm_arg_set as;
2231
2232 as.argc = argc;
2233 as.argv = argv;
2234
2235 r = parse_metadata_dev(ca, &as, error);
2236 if (r)
2237 return r;
2238
2239 r = parse_cache_dev(ca, &as, error);
2240 if (r)
2241 return r;
2242
2243 r = parse_origin_dev(ca, &as, error);
2244 if (r)
2245 return r;
2246
2247 r = parse_block_size(ca, &as, error);
2248 if (r)
2249 return r;
2250
2251 r = parse_features(ca, &as, error);
2252 if (r)
2253 return r;
2254
2255 r = parse_policy(ca, &as, error);
2256 if (r)
2257 return r;
2258
2259 return 0;
2260}
2261
2262/*----------------------------------------------------------------*/
2263
2264static struct kmem_cache *migration_cache;
2265
2266#define NOT_CORE_OPTION 1
2267
2268static int process_config_option(struct cache *cache, const char *key, const char *value)
2269{
2270 unsigned long tmp;
2271
2272 if (!strcasecmp(key, "migration_threshold")) {
2273 if (kstrtoul(value, 10, &tmp))
2274 return -EINVAL;
2275
2276 cache->migration_threshold = tmp;
2277 return 0;
2278 }
2279
2280 return NOT_CORE_OPTION;
2281}
2282
2283static int set_config_value(struct cache *cache, const char *key, const char *value)
2284{
2285 int r = process_config_option(cache, key, value);
2286
2287 if (r == NOT_CORE_OPTION)
2288 r = policy_set_config_value(cache->policy, key, value);
2289
2290 if (r)
2291 DMWARN("bad config value for %s: %s", key, value);
2292
2293 return r;
2294}
2295
2296static int set_config_values(struct cache *cache, int argc, const char **argv)
2297{
2298 int r = 0;
2299
2300 if (argc & 1) {
2301 DMWARN("Odd number of policy arguments given but they should be <key> <value> pairs.");
2302 return -EINVAL;
2303 }
2304
2305 while (argc) {
2306 r = set_config_value(cache, argv[0], argv[1]);
2307 if (r)
2308 break;
2309
2310 argc -= 2;
2311 argv += 2;
2312 }
2313
2314 return r;
2315}
2316
2317static int create_cache_policy(struct cache *cache, struct cache_args *ca,
2318 char **error)
2319{
2320 struct dm_cache_policy *p = dm_cache_policy_create(ca->policy_name,
2321 cache->cache_size,
2322 cache->origin_sectors,
2323 cache->sectors_per_block);
2324 if (IS_ERR(p)) {
2325 *error = "Error creating cache's policy";
2326 return PTR_ERR(p);
2327 }
2328 cache->policy = p;
2329 BUG_ON(!cache->policy);
2330
2331 return 0;
2332}
2333
2334/*
2335 * We want the discard block size to be at least the size of the cache
2336 * block size and have no more than 2^14 discard blocks across the origin.
2337 */
2338#define MAX_DISCARD_BLOCKS (1 << 14)
2339
2340static bool too_many_discard_blocks(sector_t discard_block_size,
2341 sector_t origin_size)
2342{
2343 (void) sector_div(origin_size, discard_block_size);
2344
2345 return origin_size > MAX_DISCARD_BLOCKS;
2346}
2347
2348static sector_t calculate_discard_block_size(sector_t cache_block_size,
2349 sector_t origin_size)
2350{
2351 sector_t discard_block_size = cache_block_size;
2352
2353 if (origin_size)
2354 while (too_many_discard_blocks(discard_block_size, origin_size))
2355 discard_block_size *= 2;
2356
2357 return discard_block_size;
2358}
2359
2360static void set_cache_size(struct cache *cache, dm_cblock_t size)
2361{
2362 dm_block_t nr_blocks = from_cblock(size);
2363
2364 if (nr_blocks > (1 << 20) && cache->cache_size != size)
2365 DMWARN_LIMIT("You have created a cache device with a lot of individual cache blocks (%llu)\n"
2366 "All these mappings can consume a lot of kernel memory, and take some time to read/write.\n"
2367 "Please consider increasing the cache block size to reduce the overall cache block count.",
2368 (unsigned long long) nr_blocks);
2369
2370 cache->cache_size = size;
2371}
2372
2373#define DEFAULT_MIGRATION_THRESHOLD 2048
2374
2375static int cache_create(struct cache_args *ca, struct cache **result)
2376{
2377 int r = 0;
2378 char **error = &ca->ti->error;
2379 struct cache *cache;
2380 struct dm_target *ti = ca->ti;
2381 dm_block_t origin_blocks;
2382 struct dm_cache_metadata *cmd;
2383 bool may_format = ca->features.mode == CM_WRITE;
2384
2385 cache = kzalloc(sizeof(*cache), GFP_KERNEL);
2386 if (!cache)
2387 return -ENOMEM;
2388
2389 cache->ti = ca->ti;
2390 ti->private = cache;
2391 ti->accounts_remapped_io = true;
2392 ti->num_flush_bios = 2;
2393 ti->flush_supported = true;
2394
2395 ti->num_discard_bios = 1;
2396 ti->discards_supported = true;
2397
2398 ti->per_io_data_size = sizeof(struct per_bio_data);
2399
2400 cache->features = ca->features;
2401 if (writethrough_mode(cache)) {
2402 /* Create bioset for writethrough bios issued to origin */
2403 r = bioset_init(&cache->bs, BIO_POOL_SIZE, 0, 0);
2404 if (r)
2405 goto bad;
2406 }
2407
2408 cache->metadata_dev = ca->metadata_dev;
2409 cache->origin_dev = ca->origin_dev;
2410 cache->cache_dev = ca->cache_dev;
2411
2412 ca->metadata_dev = ca->origin_dev = ca->cache_dev = NULL;
2413
2414 origin_blocks = cache->origin_sectors = ca->origin_sectors;
2415 origin_blocks = block_div(origin_blocks, ca->block_size);
2416 cache->origin_blocks = to_oblock(origin_blocks);
2417
2418 cache->sectors_per_block = ca->block_size;
2419 if (dm_set_target_max_io_len(ti, cache->sectors_per_block)) {
2420 r = -EINVAL;
2421 goto bad;
2422 }
2423
2424 if (ca->block_size & (ca->block_size - 1)) {
2425 dm_block_t cache_size = ca->cache_sectors;
2426
2427 cache->sectors_per_block_shift = -1;
2428 cache_size = block_div(cache_size, ca->block_size);
2429 set_cache_size(cache, to_cblock(cache_size));
2430 } else {
2431 cache->sectors_per_block_shift = __ffs(ca->block_size);
2432 set_cache_size(cache, to_cblock(ca->cache_sectors >> cache->sectors_per_block_shift));
2433 }
2434
2435 r = create_cache_policy(cache, ca, error);
2436 if (r)
2437 goto bad;
2438
2439 cache->policy_nr_args = ca->policy_argc;
2440 cache->migration_threshold = DEFAULT_MIGRATION_THRESHOLD;
2441
2442 r = set_config_values(cache, ca->policy_argc, ca->policy_argv);
2443 if (r) {
2444 *error = "Error setting cache policy's config values";
2445 goto bad;
2446 }
2447
2448 cmd = dm_cache_metadata_open(cache->metadata_dev->bdev,
2449 ca->block_size, may_format,
2450 dm_cache_policy_get_hint_size(cache->policy),
2451 ca->features.metadata_version);
2452 if (IS_ERR(cmd)) {
2453 *error = "Error creating metadata object";
2454 r = PTR_ERR(cmd);
2455 goto bad;
2456 }
2457 cache->cmd = cmd;
2458 set_cache_mode(cache, CM_WRITE);
2459 if (get_cache_mode(cache) != CM_WRITE) {
2460 *error = "Unable to get write access to metadata, please check/repair metadata.";
2461 r = -EINVAL;
2462 goto bad;
2463 }
2464
2465 if (passthrough_mode(cache)) {
2466 bool all_clean;
2467
2468 r = dm_cache_metadata_all_clean(cache->cmd, &all_clean);
2469 if (r) {
2470 *error = "dm_cache_metadata_all_clean() failed";
2471 goto bad;
2472 }
2473
2474 if (!all_clean) {
2475 *error = "Cannot enter passthrough mode unless all blocks are clean";
2476 r = -EINVAL;
2477 goto bad;
2478 }
2479
2480 policy_allow_migrations(cache->policy, false);
2481 }
2482
2483 spin_lock_init(&cache->lock);
2484 bio_list_init(&cache->deferred_bios);
2485 atomic_set(&cache->nr_allocated_migrations, 0);
2486 atomic_set(&cache->nr_io_migrations, 0);
2487 init_waitqueue_head(&cache->migration_wait);
2488
2489 r = -ENOMEM;
2490 atomic_set(&cache->nr_dirty, 0);
2491 cache->dirty_bitset = alloc_bitset(from_cblock(cache->cache_size));
2492 if (!cache->dirty_bitset) {
2493 *error = "could not allocate dirty bitset";
2494 goto bad;
2495 }
2496 clear_bitset(cache->dirty_bitset, from_cblock(cache->cache_size));
2497
2498 cache->discard_block_size =
2499 calculate_discard_block_size(cache->sectors_per_block,
2500 cache->origin_sectors);
2501 cache->discard_nr_blocks = to_dblock(dm_sector_div_up(cache->origin_sectors,
2502 cache->discard_block_size));
2503 cache->discard_bitset = alloc_bitset(from_dblock(cache->discard_nr_blocks));
2504 if (!cache->discard_bitset) {
2505 *error = "could not allocate discard bitset";
2506 goto bad;
2507 }
2508 clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks));
2509
2510 cache->copier = dm_kcopyd_client_create(&dm_kcopyd_throttle);
2511 if (IS_ERR(cache->copier)) {
2512 *error = "could not create kcopyd client";
2513 r = PTR_ERR(cache->copier);
2514 goto bad;
2515 }
2516
2517 cache->wq = alloc_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM, 0);
2518 if (!cache->wq) {
2519 *error = "could not create workqueue for metadata object";
2520 goto bad;
2521 }
2522 INIT_WORK(&cache->deferred_bio_worker, process_deferred_bios);
2523 INIT_WORK(&cache->migration_worker, check_migrations);
2524 INIT_DELAYED_WORK(&cache->waker, do_waker);
2525
2526 cache->prison = dm_bio_prison_create_v2(cache->wq);
2527 if (!cache->prison) {
2528 *error = "could not create bio prison";
2529 goto bad;
2530 }
2531
2532 r = mempool_init_slab_pool(&cache->migration_pool, MIGRATION_POOL_SIZE,
2533 migration_cache);
2534 if (r) {
2535 *error = "Error creating cache's migration mempool";
2536 goto bad;
2537 }
2538
2539 cache->need_tick_bio = true;
2540 cache->sized = false;
2541 cache->invalidate = false;
2542 cache->commit_requested = false;
2543 cache->loaded_mappings = false;
2544 cache->loaded_discards = false;
2545
2546 load_stats(cache);
2547
2548 atomic_set(&cache->stats.demotion, 0);
2549 atomic_set(&cache->stats.promotion, 0);
2550 atomic_set(&cache->stats.copies_avoided, 0);
2551 atomic_set(&cache->stats.cache_cell_clash, 0);
2552 atomic_set(&cache->stats.commit_count, 0);
2553 atomic_set(&cache->stats.discard_count, 0);
2554
2555 spin_lock_init(&cache->invalidation_lock);
2556 INIT_LIST_HEAD(&cache->invalidation_requests);
2557
2558 batcher_init(&cache->committer, commit_op, cache,
2559 issue_op, cache, cache->wq);
2560 dm_iot_init(&cache->tracker);
2561
2562 init_rwsem(&cache->background_work_lock);
2563 prevent_background_work(cache);
2564
2565 *result = cache;
2566 return 0;
2567bad:
2568 destroy(cache);
2569 return r;
2570}
2571
2572static int copy_ctr_args(struct cache *cache, int argc, const char **argv)
2573{
2574 unsigned int i;
2575 const char **copy;
2576
2577 copy = kcalloc(argc, sizeof(*copy), GFP_KERNEL);
2578 if (!copy)
2579 return -ENOMEM;
2580 for (i = 0; i < argc; i++) {
2581 copy[i] = kstrdup(argv[i], GFP_KERNEL);
2582 if (!copy[i]) {
2583 while (i--)
2584 kfree(copy[i]);
2585 kfree(copy);
2586 return -ENOMEM;
2587 }
2588 }
2589
2590 cache->nr_ctr_args = argc;
2591 cache->ctr_args = copy;
2592
2593 return 0;
2594}
2595
2596static int cache_ctr(struct dm_target *ti, unsigned int argc, char **argv)
2597{
2598 int r = -EINVAL;
2599 struct cache_args *ca;
2600 struct cache *cache = NULL;
2601
2602 ca = kzalloc(sizeof(*ca), GFP_KERNEL);
2603 if (!ca) {
2604 ti->error = "Error allocating memory for cache";
2605 return -ENOMEM;
2606 }
2607 ca->ti = ti;
2608
2609 r = parse_cache_args(ca, argc, argv, &ti->error);
2610 if (r)
2611 goto out;
2612
2613 r = cache_create(ca, &cache);
2614 if (r)
2615 goto out;
2616
2617 r = copy_ctr_args(cache, argc - 3, (const char **)argv + 3);
2618 if (r) {
2619 destroy(cache);
2620 goto out;
2621 }
2622
2623 ti->private = cache;
2624out:
2625 destroy_cache_args(ca);
2626 return r;
2627}
2628
2629/*----------------------------------------------------------------*/
2630
2631static int cache_map(struct dm_target *ti, struct bio *bio)
2632{
2633 struct cache *cache = ti->private;
2634
2635 int r;
2636 bool commit_needed;
2637 dm_oblock_t block = get_bio_block(cache, bio);
2638
2639 init_per_bio_data(bio);
2640 if (unlikely(from_oblock(block) >= from_oblock(cache->origin_blocks))) {
2641 /*
2642 * This can only occur if the io goes to a partial block at
2643 * the end of the origin device. We don't cache these.
2644 * Just remap to the origin and carry on.
2645 */
2646 remap_to_origin(cache, bio);
2647 accounted_begin(cache, bio);
2648 return DM_MAPIO_REMAPPED;
2649 }
2650
2651 if (discard_or_flush(bio)) {
2652 defer_bio(cache, bio);
2653 return DM_MAPIO_SUBMITTED;
2654 }
2655
2656 r = map_bio(cache, bio, block, &commit_needed);
2657 if (commit_needed)
2658 schedule_commit(&cache->committer);
2659
2660 return r;
2661}
2662
2663static int cache_end_io(struct dm_target *ti, struct bio *bio, blk_status_t *error)
2664{
2665 struct cache *cache = ti->private;
2666 unsigned long flags;
2667 struct per_bio_data *pb = get_per_bio_data(bio);
2668
2669 if (pb->tick) {
2670 policy_tick(cache->policy, false);
2671
2672 spin_lock_irqsave(&cache->lock, flags);
2673 cache->need_tick_bio = true;
2674 spin_unlock_irqrestore(&cache->lock, flags);
2675 }
2676
2677 bio_drop_shared_lock(cache, bio);
2678 accounted_complete(cache, bio);
2679
2680 return DM_ENDIO_DONE;
2681}
2682
2683static int write_dirty_bitset(struct cache *cache)
2684{
2685 int r;
2686
2687 if (get_cache_mode(cache) >= CM_READ_ONLY)
2688 return -EINVAL;
2689
2690 r = dm_cache_set_dirty_bits(cache->cmd, from_cblock(cache->cache_size), cache->dirty_bitset);
2691 if (r)
2692 metadata_operation_failed(cache, "dm_cache_set_dirty_bits", r);
2693
2694 return r;
2695}
2696
2697static int write_discard_bitset(struct cache *cache)
2698{
2699 unsigned int i, r;
2700
2701 if (get_cache_mode(cache) >= CM_READ_ONLY)
2702 return -EINVAL;
2703
2704 r = dm_cache_discard_bitset_resize(cache->cmd, cache->discard_block_size,
2705 cache->discard_nr_blocks);
2706 if (r) {
2707 DMERR("%s: could not resize on-disk discard bitset", cache_device_name(cache));
2708 metadata_operation_failed(cache, "dm_cache_discard_bitset_resize", r);
2709 return r;
2710 }
2711
2712 for (i = 0; i < from_dblock(cache->discard_nr_blocks); i++) {
2713 r = dm_cache_set_discard(cache->cmd, to_dblock(i),
2714 is_discarded(cache, to_dblock(i)));
2715 if (r) {
2716 metadata_operation_failed(cache, "dm_cache_set_discard", r);
2717 return r;
2718 }
2719 }
2720
2721 return 0;
2722}
2723
2724static int write_hints(struct cache *cache)
2725{
2726 int r;
2727
2728 if (get_cache_mode(cache) >= CM_READ_ONLY)
2729 return -EINVAL;
2730
2731 r = dm_cache_write_hints(cache->cmd, cache->policy);
2732 if (r) {
2733 metadata_operation_failed(cache, "dm_cache_write_hints", r);
2734 return r;
2735 }
2736
2737 return 0;
2738}
2739
2740/*
2741 * returns true on success
2742 */
2743static bool sync_metadata(struct cache *cache)
2744{
2745 int r1, r2, r3, r4;
2746
2747 r1 = write_dirty_bitset(cache);
2748 if (r1)
2749 DMERR("%s: could not write dirty bitset", cache_device_name(cache));
2750
2751 r2 = write_discard_bitset(cache);
2752 if (r2)
2753 DMERR("%s: could not write discard bitset", cache_device_name(cache));
2754
2755 save_stats(cache);
2756
2757 r3 = write_hints(cache);
2758 if (r3)
2759 DMERR("%s: could not write hints", cache_device_name(cache));
2760
2761 /*
2762 * If writing the above metadata failed, we still commit, but don't
2763 * set the clean shutdown flag. This will effectively force every
2764 * dirty bit to be set on reload.
2765 */
2766 r4 = commit(cache, !r1 && !r2 && !r3);
2767 if (r4)
2768 DMERR("%s: could not write cache metadata", cache_device_name(cache));
2769
2770 return !r1 && !r2 && !r3 && !r4;
2771}
2772
2773static void cache_postsuspend(struct dm_target *ti)
2774{
2775 struct cache *cache = ti->private;
2776
2777 prevent_background_work(cache);
2778 BUG_ON(atomic_read(&cache->nr_io_migrations));
2779
2780 cancel_delayed_work_sync(&cache->waker);
2781 drain_workqueue(cache->wq);
2782 WARN_ON(cache->tracker.in_flight);
2783
2784 /*
2785 * If it's a flush suspend there won't be any deferred bios, so this
2786 * call is harmless.
2787 */
2788 requeue_deferred_bios(cache);
2789
2790 if (get_cache_mode(cache) == CM_WRITE)
2791 (void) sync_metadata(cache);
2792}
2793
2794static int load_mapping(void *context, dm_oblock_t oblock, dm_cblock_t cblock,
2795 bool dirty, uint32_t hint, bool hint_valid)
2796{
2797 struct cache *cache = context;
2798
2799 if (dirty) {
2800 set_bit(from_cblock(cblock), cache->dirty_bitset);
2801 atomic_inc(&cache->nr_dirty);
2802 } else
2803 clear_bit(from_cblock(cblock), cache->dirty_bitset);
2804
2805 return policy_load_mapping(cache->policy, oblock, cblock, dirty, hint, hint_valid);
2806}
2807
2808/*
2809 * The discard block size in the on disk metadata is not
2810 * necessarily the same as we're currently using. So we have to
2811 * be careful to only set the discarded attribute if we know it
2812 * covers a complete block of the new size.
2813 */
2814struct discard_load_info {
2815 struct cache *cache;
2816
2817 /*
2818 * These blocks are sized using the on disk dblock size, rather
2819 * than the current one.
2820 */
2821 dm_block_t block_size;
2822 dm_block_t discard_begin, discard_end;
2823};
2824
2825static void discard_load_info_init(struct cache *cache,
2826 struct discard_load_info *li)
2827{
2828 li->cache = cache;
2829 li->discard_begin = li->discard_end = 0;
2830}
2831
2832static void set_discard_range(struct discard_load_info *li)
2833{
2834 sector_t b, e;
2835
2836 if (li->discard_begin == li->discard_end)
2837 return;
2838
2839 /*
2840 * Convert to sectors.
2841 */
2842 b = li->discard_begin * li->block_size;
2843 e = li->discard_end * li->block_size;
2844
2845 /*
2846 * Then convert back to the current dblock size.
2847 */
2848 b = dm_sector_div_up(b, li->cache->discard_block_size);
2849 sector_div(e, li->cache->discard_block_size);
2850
2851 /*
2852 * The origin may have shrunk, so we need to check we're still in
2853 * bounds.
2854 */
2855 if (e > from_dblock(li->cache->discard_nr_blocks))
2856 e = from_dblock(li->cache->discard_nr_blocks);
2857
2858 for (; b < e; b++)
2859 set_discard(li->cache, to_dblock(b));
2860}
2861
2862static int load_discard(void *context, sector_t discard_block_size,
2863 dm_dblock_t dblock, bool discard)
2864{
2865 struct discard_load_info *li = context;
2866
2867 li->block_size = discard_block_size;
2868
2869 if (discard) {
2870 if (from_dblock(dblock) == li->discard_end)
2871 /*
2872 * We're already in a discard range, just extend it.
2873 */
2874 li->discard_end = li->discard_end + 1ULL;
2875
2876 else {
2877 /*
2878 * Emit the old range and start a new one.
2879 */
2880 set_discard_range(li);
2881 li->discard_begin = from_dblock(dblock);
2882 li->discard_end = li->discard_begin + 1ULL;
2883 }
2884 } else {
2885 set_discard_range(li);
2886 li->discard_begin = li->discard_end = 0;
2887 }
2888
2889 return 0;
2890}
2891
2892static dm_cblock_t get_cache_dev_size(struct cache *cache)
2893{
2894 sector_t size = get_dev_size(cache->cache_dev);
2895 (void) sector_div(size, cache->sectors_per_block);
2896 return to_cblock(size);
2897}
2898
2899static bool can_resize(struct cache *cache, dm_cblock_t new_size)
2900{
2901 if (from_cblock(new_size) > from_cblock(cache->cache_size)) {
2902 if (cache->sized) {
2903 DMERR("%s: unable to extend cache due to missing cache table reload",
2904 cache_device_name(cache));
2905 return false;
2906 }
2907 }
2908
2909 /*
2910 * We can't drop a dirty block when shrinking the cache.
2911 */
2912 while (from_cblock(new_size) < from_cblock(cache->cache_size)) {
2913 new_size = to_cblock(from_cblock(new_size) + 1);
2914 if (is_dirty(cache, new_size)) {
2915 DMERR("%s: unable to shrink cache; cache block %llu is dirty",
2916 cache_device_name(cache),
2917 (unsigned long long) from_cblock(new_size));
2918 return false;
2919 }
2920 }
2921
2922 return true;
2923}
2924
2925static int resize_cache_dev(struct cache *cache, dm_cblock_t new_size)
2926{
2927 int r;
2928
2929 r = dm_cache_resize(cache->cmd, new_size);
2930 if (r) {
2931 DMERR("%s: could not resize cache metadata", cache_device_name(cache));
2932 metadata_operation_failed(cache, "dm_cache_resize", r);
2933 return r;
2934 }
2935
2936 set_cache_size(cache, new_size);
2937
2938 return 0;
2939}
2940
2941static int cache_preresume(struct dm_target *ti)
2942{
2943 int r = 0;
2944 struct cache *cache = ti->private;
2945 dm_cblock_t csize = get_cache_dev_size(cache);
2946
2947 /*
2948 * Check to see if the cache has resized.
2949 */
2950 if (!cache->sized) {
2951 r = resize_cache_dev(cache, csize);
2952 if (r)
2953 return r;
2954
2955 cache->sized = true;
2956
2957 } else if (csize != cache->cache_size) {
2958 if (!can_resize(cache, csize))
2959 return -EINVAL;
2960
2961 r = resize_cache_dev(cache, csize);
2962 if (r)
2963 return r;
2964 }
2965
2966 if (!cache->loaded_mappings) {
2967 r = dm_cache_load_mappings(cache->cmd, cache->policy,
2968 load_mapping, cache);
2969 if (r) {
2970 DMERR("%s: could not load cache mappings", cache_device_name(cache));
2971 metadata_operation_failed(cache, "dm_cache_load_mappings", r);
2972 return r;
2973 }
2974
2975 cache->loaded_mappings = true;
2976 }
2977
2978 if (!cache->loaded_discards) {
2979 struct discard_load_info li;
2980
2981 /*
2982 * The discard bitset could have been resized, or the
2983 * discard block size changed. To be safe we start by
2984 * setting every dblock to not discarded.
2985 */
2986 clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks));
2987
2988 discard_load_info_init(cache, &li);
2989 r = dm_cache_load_discards(cache->cmd, load_discard, &li);
2990 if (r) {
2991 DMERR("%s: could not load origin discards", cache_device_name(cache));
2992 metadata_operation_failed(cache, "dm_cache_load_discards", r);
2993 return r;
2994 }
2995 set_discard_range(&li);
2996
2997 cache->loaded_discards = true;
2998 }
2999
3000 return r;
3001}
3002
3003static void cache_resume(struct dm_target *ti)
3004{
3005 struct cache *cache = ti->private;
3006
3007 cache->need_tick_bio = true;
3008 allow_background_work(cache);
3009 do_waker(&cache->waker.work);
3010}
3011
3012static void emit_flags(struct cache *cache, char *result,
3013 unsigned int maxlen, ssize_t *sz_ptr)
3014{
3015 ssize_t sz = *sz_ptr;
3016 struct cache_features *cf = &cache->features;
3017 unsigned int count = (cf->metadata_version == 2) + !cf->discard_passdown + 1;
3018
3019 DMEMIT("%u ", count);
3020
3021 if (cf->metadata_version == 2)
3022 DMEMIT("metadata2 ");
3023
3024 if (writethrough_mode(cache))
3025 DMEMIT("writethrough ");
3026
3027 else if (passthrough_mode(cache))
3028 DMEMIT("passthrough ");
3029
3030 else if (writeback_mode(cache))
3031 DMEMIT("writeback ");
3032
3033 else {
3034 DMEMIT("unknown ");
3035 DMERR("%s: internal error: unknown io mode: %d",
3036 cache_device_name(cache), (int) cf->io_mode);
3037 }
3038
3039 if (!cf->discard_passdown)
3040 DMEMIT("no_discard_passdown ");
3041
3042 *sz_ptr = sz;
3043}
3044
3045/*
3046 * Status format:
3047 *
3048 * <metadata block size> <#used metadata blocks>/<#total metadata blocks>
3049 * <cache block size> <#used cache blocks>/<#total cache blocks>
3050 * <#read hits> <#read misses> <#write hits> <#write misses>
3051 * <#demotions> <#promotions> <#dirty>
3052 * <#features> <features>*
3053 * <#core args> <core args>
3054 * <policy name> <#policy args> <policy args>* <cache metadata mode> <needs_check>
3055 */
3056static void cache_status(struct dm_target *ti, status_type_t type,
3057 unsigned int status_flags, char *result, unsigned int maxlen)
3058{
3059 int r = 0;
3060 unsigned int i;
3061 ssize_t sz = 0;
3062 dm_block_t nr_free_blocks_metadata = 0;
3063 dm_block_t nr_blocks_metadata = 0;
3064 char buf[BDEVNAME_SIZE];
3065 struct cache *cache = ti->private;
3066 dm_cblock_t residency;
3067 bool needs_check;
3068
3069 switch (type) {
3070 case STATUSTYPE_INFO:
3071 if (get_cache_mode(cache) == CM_FAIL) {
3072 DMEMIT("Fail");
3073 break;
3074 }
3075
3076 /* Commit to ensure statistics aren't out-of-date */
3077 if (!(status_flags & DM_STATUS_NOFLUSH_FLAG) && !dm_suspended(ti))
3078 (void) commit(cache, false);
3079
3080 r = dm_cache_get_free_metadata_block_count(cache->cmd, &nr_free_blocks_metadata);
3081 if (r) {
3082 DMERR("%s: dm_cache_get_free_metadata_block_count returned %d",
3083 cache_device_name(cache), r);
3084 goto err;
3085 }
3086
3087 r = dm_cache_get_metadata_dev_size(cache->cmd, &nr_blocks_metadata);
3088 if (r) {
3089 DMERR("%s: dm_cache_get_metadata_dev_size returned %d",
3090 cache_device_name(cache), r);
3091 goto err;
3092 }
3093
3094 residency = policy_residency(cache->policy);
3095
3096 DMEMIT("%u %llu/%llu %llu %llu/%llu %u %u %u %u %u %u %lu ",
3097 (unsigned int)DM_CACHE_METADATA_BLOCK_SIZE,
3098 (unsigned long long)(nr_blocks_metadata - nr_free_blocks_metadata),
3099 (unsigned long long)nr_blocks_metadata,
3100 (unsigned long long)cache->sectors_per_block,
3101 (unsigned long long) from_cblock(residency),
3102 (unsigned long long) from_cblock(cache->cache_size),
3103 (unsigned int) atomic_read(&cache->stats.read_hit),
3104 (unsigned int) atomic_read(&cache->stats.read_miss),
3105 (unsigned int) atomic_read(&cache->stats.write_hit),
3106 (unsigned int) atomic_read(&cache->stats.write_miss),
3107 (unsigned int) atomic_read(&cache->stats.demotion),
3108 (unsigned int) atomic_read(&cache->stats.promotion),
3109 (unsigned long) atomic_read(&cache->nr_dirty));
3110
3111 emit_flags(cache, result, maxlen, &sz);
3112
3113 DMEMIT("2 migration_threshold %llu ", (unsigned long long) cache->migration_threshold);
3114
3115 DMEMIT("%s ", dm_cache_policy_get_name(cache->policy));
3116 if (sz < maxlen) {
3117 r = policy_emit_config_values(cache->policy, result, maxlen, &sz);
3118 if (r)
3119 DMERR("%s: policy_emit_config_values returned %d",
3120 cache_device_name(cache), r);
3121 }
3122
3123 if (get_cache_mode(cache) == CM_READ_ONLY)
3124 DMEMIT("ro ");
3125 else
3126 DMEMIT("rw ");
3127
3128 r = dm_cache_metadata_needs_check(cache->cmd, &needs_check);
3129
3130 if (r || needs_check)
3131 DMEMIT("needs_check ");
3132 else
3133 DMEMIT("- ");
3134
3135 break;
3136
3137 case STATUSTYPE_TABLE:
3138 format_dev_t(buf, cache->metadata_dev->bdev->bd_dev);
3139 DMEMIT("%s ", buf);
3140 format_dev_t(buf, cache->cache_dev->bdev->bd_dev);
3141 DMEMIT("%s ", buf);
3142 format_dev_t(buf, cache->origin_dev->bdev->bd_dev);
3143 DMEMIT("%s", buf);
3144
3145 for (i = 0; i < cache->nr_ctr_args - 1; i++)
3146 DMEMIT(" %s", cache->ctr_args[i]);
3147 if (cache->nr_ctr_args)
3148 DMEMIT(" %s", cache->ctr_args[cache->nr_ctr_args - 1]);
3149 break;
3150
3151 case STATUSTYPE_IMA:
3152 DMEMIT_TARGET_NAME_VERSION(ti->type);
3153 if (get_cache_mode(cache) == CM_FAIL)
3154 DMEMIT(",metadata_mode=fail");
3155 else if (get_cache_mode(cache) == CM_READ_ONLY)
3156 DMEMIT(",metadata_mode=ro");
3157 else
3158 DMEMIT(",metadata_mode=rw");
3159
3160 format_dev_t(buf, cache->metadata_dev->bdev->bd_dev);
3161 DMEMIT(",cache_metadata_device=%s", buf);
3162 format_dev_t(buf, cache->cache_dev->bdev->bd_dev);
3163 DMEMIT(",cache_device=%s", buf);
3164 format_dev_t(buf, cache->origin_dev->bdev->bd_dev);
3165 DMEMIT(",cache_origin_device=%s", buf);
3166 DMEMIT(",writethrough=%c", writethrough_mode(cache) ? 'y' : 'n');
3167 DMEMIT(",writeback=%c", writeback_mode(cache) ? 'y' : 'n');
3168 DMEMIT(",passthrough=%c", passthrough_mode(cache) ? 'y' : 'n');
3169 DMEMIT(",metadata2=%c", cache->features.metadata_version == 2 ? 'y' : 'n');
3170 DMEMIT(",no_discard_passdown=%c", cache->features.discard_passdown ? 'n' : 'y');
3171 DMEMIT(";");
3172 break;
3173 }
3174
3175 return;
3176
3177err:
3178 DMEMIT("Error");
3179}
3180
3181/*
3182 * Defines a range of cblocks, begin to (end - 1) are in the range. end is
3183 * the one-past-the-end value.
3184 */
3185struct cblock_range {
3186 dm_cblock_t begin;
3187 dm_cblock_t end;
3188};
3189
3190/*
3191 * A cache block range can take two forms:
3192 *
3193 * i) A single cblock, eg. '3456'
3194 * ii) A begin and end cblock with a dash between, eg. 123-234
3195 */
3196static int parse_cblock_range(struct cache *cache, const char *str,
3197 struct cblock_range *result)
3198{
3199 char dummy;
3200 uint64_t b, e;
3201 int r;
3202
3203 /*
3204 * Try and parse form (ii) first.
3205 */
3206 r = sscanf(str, "%llu-%llu%c", &b, &e, &dummy);
3207 if (r < 0)
3208 return r;
3209
3210 if (r == 2) {
3211 result->begin = to_cblock(b);
3212 result->end = to_cblock(e);
3213 return 0;
3214 }
3215
3216 /*
3217 * That didn't work, try form (i).
3218 */
3219 r = sscanf(str, "%llu%c", &b, &dummy);
3220 if (r < 0)
3221 return r;
3222
3223 if (r == 1) {
3224 result->begin = to_cblock(b);
3225 result->end = to_cblock(from_cblock(result->begin) + 1u);
3226 return 0;
3227 }
3228
3229 DMERR("%s: invalid cblock range '%s'", cache_device_name(cache), str);
3230 return -EINVAL;
3231}
3232
3233static int validate_cblock_range(struct cache *cache, struct cblock_range *range)
3234{
3235 uint64_t b = from_cblock(range->begin);
3236 uint64_t e = from_cblock(range->end);
3237 uint64_t n = from_cblock(cache->cache_size);
3238
3239 if (b >= n) {
3240 DMERR("%s: begin cblock out of range: %llu >= %llu",
3241 cache_device_name(cache), b, n);
3242 return -EINVAL;
3243 }
3244
3245 if (e > n) {
3246 DMERR("%s: end cblock out of range: %llu > %llu",
3247 cache_device_name(cache), e, n);
3248 return -EINVAL;
3249 }
3250
3251 if (b >= e) {
3252 DMERR("%s: invalid cblock range: %llu >= %llu",
3253 cache_device_name(cache), b, e);
3254 return -EINVAL;
3255 }
3256
3257 return 0;
3258}
3259
3260static inline dm_cblock_t cblock_succ(dm_cblock_t b)
3261{
3262 return to_cblock(from_cblock(b) + 1);
3263}
3264
3265static int request_invalidation(struct cache *cache, struct cblock_range *range)
3266{
3267 int r = 0;
3268
3269 /*
3270 * We don't need to do any locking here because we know we're in
3271 * passthrough mode. There's is potential for a race between an
3272 * invalidation triggered by an io and an invalidation message. This
3273 * is harmless, we must not worry if the policy call fails.
3274 */
3275 while (range->begin != range->end) {
3276 r = invalidate_cblock(cache, range->begin);
3277 if (r)
3278 return r;
3279
3280 range->begin = cblock_succ(range->begin);
3281 }
3282
3283 cache->commit_requested = true;
3284 return r;
3285}
3286
3287static int process_invalidate_cblocks_message(struct cache *cache, unsigned int count,
3288 const char **cblock_ranges)
3289{
3290 int r = 0;
3291 unsigned int i;
3292 struct cblock_range range;
3293
3294 if (!passthrough_mode(cache)) {
3295 DMERR("%s: cache has to be in passthrough mode for invalidation",
3296 cache_device_name(cache));
3297 return -EPERM;
3298 }
3299
3300 for (i = 0; i < count; i++) {
3301 r = parse_cblock_range(cache, cblock_ranges[i], &range);
3302 if (r)
3303 break;
3304
3305 r = validate_cblock_range(cache, &range);
3306 if (r)
3307 break;
3308
3309 /*
3310 * Pass begin and end origin blocks to the worker and wake it.
3311 */
3312 r = request_invalidation(cache, &range);
3313 if (r)
3314 break;
3315 }
3316
3317 return r;
3318}
3319
3320/*
3321 * Supports
3322 * "<key> <value>"
3323 * and
3324 * "invalidate_cblocks [(<begin>)|(<begin>-<end>)]*
3325 *
3326 * The key migration_threshold is supported by the cache target core.
3327 */
3328static int cache_message(struct dm_target *ti, unsigned int argc, char **argv,
3329 char *result, unsigned int maxlen)
3330{
3331 struct cache *cache = ti->private;
3332
3333 if (!argc)
3334 return -EINVAL;
3335
3336 if (get_cache_mode(cache) >= CM_READ_ONLY) {
3337 DMERR("%s: unable to service cache target messages in READ_ONLY or FAIL mode",
3338 cache_device_name(cache));
3339 return -EOPNOTSUPP;
3340 }
3341
3342 if (!strcasecmp(argv[0], "invalidate_cblocks"))
3343 return process_invalidate_cblocks_message(cache, argc - 1, (const char **) argv + 1);
3344
3345 if (argc != 2)
3346 return -EINVAL;
3347
3348 return set_config_value(cache, argv[0], argv[1]);
3349}
3350
3351static int cache_iterate_devices(struct dm_target *ti,
3352 iterate_devices_callout_fn fn, void *data)
3353{
3354 int r = 0;
3355 struct cache *cache = ti->private;
3356
3357 r = fn(ti, cache->cache_dev, 0, get_dev_size(cache->cache_dev), data);
3358 if (!r)
3359 r = fn(ti, cache->origin_dev, 0, ti->len, data);
3360
3361 return r;
3362}
3363
3364/*
3365 * If discard_passdown was enabled verify that the origin device
3366 * supports discards. Disable discard_passdown if not.
3367 */
3368static void disable_passdown_if_not_supported(struct cache *cache)
3369{
3370 struct block_device *origin_bdev = cache->origin_dev->bdev;
3371 struct queue_limits *origin_limits = &bdev_get_queue(origin_bdev)->limits;
3372 const char *reason = NULL;
3373
3374 if (!cache->features.discard_passdown)
3375 return;
3376
3377 if (!bdev_max_discard_sectors(origin_bdev))
3378 reason = "discard unsupported";
3379
3380 else if (origin_limits->max_discard_sectors < cache->sectors_per_block)
3381 reason = "max discard sectors smaller than a block";
3382
3383 if (reason) {
3384 DMWARN("Origin device (%pg) %s: Disabling discard passdown.",
3385 origin_bdev, reason);
3386 cache->features.discard_passdown = false;
3387 }
3388}
3389
3390static void set_discard_limits(struct cache *cache, struct queue_limits *limits)
3391{
3392 struct block_device *origin_bdev = cache->origin_dev->bdev;
3393 struct queue_limits *origin_limits = &bdev_get_queue(origin_bdev)->limits;
3394
3395 if (!cache->features.discard_passdown) {
3396 /* No passdown is done so setting own virtual limits */
3397 limits->max_discard_sectors = min_t(sector_t, cache->discard_block_size * 1024,
3398 cache->origin_sectors);
3399 limits->discard_granularity = cache->discard_block_size << SECTOR_SHIFT;
3400 return;
3401 }
3402
3403 /*
3404 * cache_iterate_devices() is stacking both origin and fast device limits
3405 * but discards aren't passed to fast device, so inherit origin's limits.
3406 */
3407 limits->max_discard_sectors = origin_limits->max_discard_sectors;
3408 limits->max_hw_discard_sectors = origin_limits->max_hw_discard_sectors;
3409 limits->discard_granularity = origin_limits->discard_granularity;
3410 limits->discard_alignment = origin_limits->discard_alignment;
3411 limits->discard_misaligned = origin_limits->discard_misaligned;
3412}
3413
3414static void cache_io_hints(struct dm_target *ti, struct queue_limits *limits)
3415{
3416 struct cache *cache = ti->private;
3417 uint64_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;
3418
3419 /*
3420 * If the system-determined stacked limits are compatible with the
3421 * cache's blocksize (io_opt is a factor) do not override them.
3422 */
3423 if (io_opt_sectors < cache->sectors_per_block ||
3424 do_div(io_opt_sectors, cache->sectors_per_block)) {
3425 blk_limits_io_min(limits, cache->sectors_per_block << SECTOR_SHIFT);
3426 blk_limits_io_opt(limits, cache->sectors_per_block << SECTOR_SHIFT);
3427 }
3428
3429 disable_passdown_if_not_supported(cache);
3430 set_discard_limits(cache, limits);
3431}
3432
3433/*----------------------------------------------------------------*/
3434
3435static struct target_type cache_target = {
3436 .name = "cache",
3437 .version = {2, 2, 0},
3438 .module = THIS_MODULE,
3439 .ctr = cache_ctr,
3440 .dtr = cache_dtr,
3441 .map = cache_map,
3442 .end_io = cache_end_io,
3443 .postsuspend = cache_postsuspend,
3444 .preresume = cache_preresume,
3445 .resume = cache_resume,
3446 .status = cache_status,
3447 .message = cache_message,
3448 .iterate_devices = cache_iterate_devices,
3449 .io_hints = cache_io_hints,
3450};
3451
3452static int __init dm_cache_init(void)
3453{
3454 int r;
3455
3456 migration_cache = KMEM_CACHE(dm_cache_migration, 0);
3457 if (!migration_cache)
3458 return -ENOMEM;
3459
3460 r = dm_register_target(&cache_target);
3461 if (r) {
3462 kmem_cache_destroy(migration_cache);
3463 return r;
3464 }
3465
3466 return 0;
3467}
3468
3469static void __exit dm_cache_exit(void)
3470{
3471 dm_unregister_target(&cache_target);
3472 kmem_cache_destroy(migration_cache);
3473}
3474
3475module_init(dm_cache_init);
3476module_exit(dm_cache_exit);
3477
3478MODULE_DESCRIPTION(DM_NAME " cache target");
3479MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
3480MODULE_LICENSE("GPL");
1/*
2 * Copyright (C) 2012 Red Hat. All rights reserved.
3 *
4 * This file is released under the GPL.
5 */
6
7#include "dm.h"
8#include "dm-bio-prison.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/init.h>
15#include <linux/mempool.h>
16#include <linux/module.h>
17#include <linux/slab.h>
18#include <linux/vmalloc.h>
19
20#define DM_MSG_PREFIX "cache"
21
22DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(cache_copy_throttle,
23 "A percentage of time allocated for copying to and/or from cache");
24
25/*----------------------------------------------------------------*/
26
27/*
28 * Glossary:
29 *
30 * oblock: index of an origin block
31 * cblock: index of a cache block
32 * promotion: movement of a block from origin to cache
33 * demotion: movement of a block from cache to origin
34 * migration: movement of a block between the origin and cache device,
35 * either direction
36 */
37
38/*----------------------------------------------------------------*/
39
40static size_t bitset_size_in_bytes(unsigned nr_entries)
41{
42 return sizeof(unsigned long) * dm_div_up(nr_entries, BITS_PER_LONG);
43}
44
45static unsigned long *alloc_bitset(unsigned nr_entries)
46{
47 size_t s = bitset_size_in_bytes(nr_entries);
48 return vzalloc(s);
49}
50
51static void clear_bitset(void *bitset, unsigned nr_entries)
52{
53 size_t s = bitset_size_in_bytes(nr_entries);
54 memset(bitset, 0, s);
55}
56
57static void free_bitset(unsigned long *bits)
58{
59 vfree(bits);
60}
61
62/*----------------------------------------------------------------*/
63
64/*
65 * There are a couple of places where we let a bio run, but want to do some
66 * work before calling its endio function. We do this by temporarily
67 * changing the endio fn.
68 */
69struct dm_hook_info {
70 bio_end_io_t *bi_end_io;
71 void *bi_private;
72};
73
74static void dm_hook_bio(struct dm_hook_info *h, struct bio *bio,
75 bio_end_io_t *bi_end_io, void *bi_private)
76{
77 h->bi_end_io = bio->bi_end_io;
78 h->bi_private = bio->bi_private;
79
80 bio->bi_end_io = bi_end_io;
81 bio->bi_private = bi_private;
82}
83
84static void dm_unhook_bio(struct dm_hook_info *h, struct bio *bio)
85{
86 bio->bi_end_io = h->bi_end_io;
87 bio->bi_private = h->bi_private;
88
89 /*
90 * Must bump bi_remaining to allow bio to complete with
91 * restored bi_end_io.
92 */
93 atomic_inc(&bio->bi_remaining);
94}
95
96/*----------------------------------------------------------------*/
97
98#define PRISON_CELLS 1024
99#define MIGRATION_POOL_SIZE 128
100#define COMMIT_PERIOD HZ
101#define MIGRATION_COUNT_WINDOW 10
102
103/*
104 * The block size of the device holding cache data must be
105 * between 32KB and 1GB.
106 */
107#define DATA_DEV_BLOCK_SIZE_MIN_SECTORS (32 * 1024 >> SECTOR_SHIFT)
108#define DATA_DEV_BLOCK_SIZE_MAX_SECTORS (1024 * 1024 * 1024 >> SECTOR_SHIFT)
109
110/*
111 * FIXME: the cache is read/write for the time being.
112 */
113enum cache_metadata_mode {
114 CM_WRITE, /* metadata may be changed */
115 CM_READ_ONLY, /* metadata may not be changed */
116};
117
118enum cache_io_mode {
119 /*
120 * Data is written to cached blocks only. These blocks are marked
121 * dirty. If you lose the cache device you will lose data.
122 * Potential performance increase for both reads and writes.
123 */
124 CM_IO_WRITEBACK,
125
126 /*
127 * Data is written to both cache and origin. Blocks are never
128 * dirty. Potential performance benfit for reads only.
129 */
130 CM_IO_WRITETHROUGH,
131
132 /*
133 * A degraded mode useful for various cache coherency situations
134 * (eg, rolling back snapshots). Reads and writes always go to the
135 * origin. If a write goes to a cached oblock, then the cache
136 * block is invalidated.
137 */
138 CM_IO_PASSTHROUGH
139};
140
141struct cache_features {
142 enum cache_metadata_mode mode;
143 enum cache_io_mode io_mode;
144};
145
146struct cache_stats {
147 atomic_t read_hit;
148 atomic_t read_miss;
149 atomic_t write_hit;
150 atomic_t write_miss;
151 atomic_t demotion;
152 atomic_t promotion;
153 atomic_t copies_avoided;
154 atomic_t cache_cell_clash;
155 atomic_t commit_count;
156 atomic_t discard_count;
157};
158
159/*
160 * Defines a range of cblocks, begin to (end - 1) are in the range. end is
161 * the one-past-the-end value.
162 */
163struct cblock_range {
164 dm_cblock_t begin;
165 dm_cblock_t end;
166};
167
168struct invalidation_request {
169 struct list_head list;
170 struct cblock_range *cblocks;
171
172 atomic_t complete;
173 int err;
174
175 wait_queue_head_t result_wait;
176};
177
178struct cache {
179 struct dm_target *ti;
180 struct dm_target_callbacks callbacks;
181
182 struct dm_cache_metadata *cmd;
183
184 /*
185 * Metadata is written to this device.
186 */
187 struct dm_dev *metadata_dev;
188
189 /*
190 * The slower of the two data devices. Typically a spindle.
191 */
192 struct dm_dev *origin_dev;
193
194 /*
195 * The faster of the two data devices. Typically an SSD.
196 */
197 struct dm_dev *cache_dev;
198
199 /*
200 * Size of the origin device in _complete_ blocks and native sectors.
201 */
202 dm_oblock_t origin_blocks;
203 sector_t origin_sectors;
204
205 /*
206 * Size of the cache device in blocks.
207 */
208 dm_cblock_t cache_size;
209
210 /*
211 * Fields for converting from sectors to blocks.
212 */
213 uint32_t sectors_per_block;
214 int sectors_per_block_shift;
215
216 spinlock_t lock;
217 struct bio_list deferred_bios;
218 struct bio_list deferred_flush_bios;
219 struct bio_list deferred_writethrough_bios;
220 struct list_head quiesced_migrations;
221 struct list_head completed_migrations;
222 struct list_head need_commit_migrations;
223 sector_t migration_threshold;
224 wait_queue_head_t migration_wait;
225 atomic_t nr_migrations;
226
227 wait_queue_head_t quiescing_wait;
228 atomic_t quiescing;
229 atomic_t quiescing_ack;
230
231 /*
232 * cache_size entries, dirty if set
233 */
234 dm_cblock_t nr_dirty;
235 unsigned long *dirty_bitset;
236
237 /*
238 * origin_blocks entries, discarded if set.
239 */
240 dm_oblock_t discard_nr_blocks;
241 unsigned long *discard_bitset;
242
243 /*
244 * Rather than reconstructing the table line for the status we just
245 * save it and regurgitate.
246 */
247 unsigned nr_ctr_args;
248 const char **ctr_args;
249
250 struct dm_kcopyd_client *copier;
251 struct workqueue_struct *wq;
252 struct work_struct worker;
253
254 struct delayed_work waker;
255 unsigned long last_commit_jiffies;
256
257 struct dm_bio_prison *prison;
258 struct dm_deferred_set *all_io_ds;
259
260 mempool_t *migration_pool;
261 struct dm_cache_migration *next_migration;
262
263 struct dm_cache_policy *policy;
264 unsigned policy_nr_args;
265
266 bool need_tick_bio:1;
267 bool sized:1;
268 bool invalidate:1;
269 bool commit_requested:1;
270 bool loaded_mappings:1;
271 bool loaded_discards:1;
272
273 /*
274 * Cache features such as write-through.
275 */
276 struct cache_features features;
277
278 struct cache_stats stats;
279
280 /*
281 * Invalidation fields.
282 */
283 spinlock_t invalidation_lock;
284 struct list_head invalidation_requests;
285};
286
287struct per_bio_data {
288 bool tick:1;
289 unsigned req_nr:2;
290 struct dm_deferred_entry *all_io_entry;
291 struct dm_hook_info hook_info;
292
293 /*
294 * writethrough fields. These MUST remain at the end of this
295 * structure and the 'cache' member must be the first as it
296 * is used to determine the offset of the writethrough fields.
297 */
298 struct cache *cache;
299 dm_cblock_t cblock;
300 struct dm_bio_details bio_details;
301};
302
303struct dm_cache_migration {
304 struct list_head list;
305 struct cache *cache;
306
307 unsigned long start_jiffies;
308 dm_oblock_t old_oblock;
309 dm_oblock_t new_oblock;
310 dm_cblock_t cblock;
311
312 bool err:1;
313 bool writeback:1;
314 bool demote:1;
315 bool promote:1;
316 bool requeue_holder:1;
317 bool invalidate:1;
318
319 struct dm_bio_prison_cell *old_ocell;
320 struct dm_bio_prison_cell *new_ocell;
321};
322
323/*
324 * Processing a bio in the worker thread may require these memory
325 * allocations. We prealloc to avoid deadlocks (the same worker thread
326 * frees them back to the mempool).
327 */
328struct prealloc {
329 struct dm_cache_migration *mg;
330 struct dm_bio_prison_cell *cell1;
331 struct dm_bio_prison_cell *cell2;
332};
333
334static void wake_worker(struct cache *cache)
335{
336 queue_work(cache->wq, &cache->worker);
337}
338
339/*----------------------------------------------------------------*/
340
341static struct dm_bio_prison_cell *alloc_prison_cell(struct cache *cache)
342{
343 /* FIXME: change to use a local slab. */
344 return dm_bio_prison_alloc_cell(cache->prison, GFP_NOWAIT);
345}
346
347static void free_prison_cell(struct cache *cache, struct dm_bio_prison_cell *cell)
348{
349 dm_bio_prison_free_cell(cache->prison, cell);
350}
351
352static int prealloc_data_structs(struct cache *cache, struct prealloc *p)
353{
354 if (!p->mg) {
355 p->mg = mempool_alloc(cache->migration_pool, GFP_NOWAIT);
356 if (!p->mg)
357 return -ENOMEM;
358 }
359
360 if (!p->cell1) {
361 p->cell1 = alloc_prison_cell(cache);
362 if (!p->cell1)
363 return -ENOMEM;
364 }
365
366 if (!p->cell2) {
367 p->cell2 = alloc_prison_cell(cache);
368 if (!p->cell2)
369 return -ENOMEM;
370 }
371
372 return 0;
373}
374
375static void prealloc_free_structs(struct cache *cache, struct prealloc *p)
376{
377 if (p->cell2)
378 free_prison_cell(cache, p->cell2);
379
380 if (p->cell1)
381 free_prison_cell(cache, p->cell1);
382
383 if (p->mg)
384 mempool_free(p->mg, cache->migration_pool);
385}
386
387static struct dm_cache_migration *prealloc_get_migration(struct prealloc *p)
388{
389 struct dm_cache_migration *mg = p->mg;
390
391 BUG_ON(!mg);
392 p->mg = NULL;
393
394 return mg;
395}
396
397/*
398 * You must have a cell within the prealloc struct to return. If not this
399 * function will BUG() rather than returning NULL.
400 */
401static struct dm_bio_prison_cell *prealloc_get_cell(struct prealloc *p)
402{
403 struct dm_bio_prison_cell *r = NULL;
404
405 if (p->cell1) {
406 r = p->cell1;
407 p->cell1 = NULL;
408
409 } else if (p->cell2) {
410 r = p->cell2;
411 p->cell2 = NULL;
412 } else
413 BUG();
414
415 return r;
416}
417
418/*
419 * You can't have more than two cells in a prealloc struct. BUG() will be
420 * called if you try and overfill.
421 */
422static void prealloc_put_cell(struct prealloc *p, struct dm_bio_prison_cell *cell)
423{
424 if (!p->cell2)
425 p->cell2 = cell;
426
427 else if (!p->cell1)
428 p->cell1 = cell;
429
430 else
431 BUG();
432}
433
434/*----------------------------------------------------------------*/
435
436static void build_key(dm_oblock_t oblock, struct dm_cell_key *key)
437{
438 key->virtual = 0;
439 key->dev = 0;
440 key->block = from_oblock(oblock);
441}
442
443/*
444 * The caller hands in a preallocated cell, and a free function for it.
445 * The cell will be freed if there's an error, or if it wasn't used because
446 * a cell with that key already exists.
447 */
448typedef void (*cell_free_fn)(void *context, struct dm_bio_prison_cell *cell);
449
450static int bio_detain(struct cache *cache, dm_oblock_t oblock,
451 struct bio *bio, struct dm_bio_prison_cell *cell_prealloc,
452 cell_free_fn free_fn, void *free_context,
453 struct dm_bio_prison_cell **cell_result)
454{
455 int r;
456 struct dm_cell_key key;
457
458 build_key(oblock, &key);
459 r = dm_bio_detain(cache->prison, &key, bio, cell_prealloc, cell_result);
460 if (r)
461 free_fn(free_context, cell_prealloc);
462
463 return r;
464}
465
466static int get_cell(struct cache *cache,
467 dm_oblock_t oblock,
468 struct prealloc *structs,
469 struct dm_bio_prison_cell **cell_result)
470{
471 int r;
472 struct dm_cell_key key;
473 struct dm_bio_prison_cell *cell_prealloc;
474
475 cell_prealloc = prealloc_get_cell(structs);
476
477 build_key(oblock, &key);
478 r = dm_get_cell(cache->prison, &key, cell_prealloc, cell_result);
479 if (r)
480 prealloc_put_cell(structs, cell_prealloc);
481
482 return r;
483}
484
485/*----------------------------------------------------------------*/
486
487static bool is_dirty(struct cache *cache, dm_cblock_t b)
488{
489 return test_bit(from_cblock(b), cache->dirty_bitset);
490}
491
492static void set_dirty(struct cache *cache, dm_oblock_t oblock, dm_cblock_t cblock)
493{
494 if (!test_and_set_bit(from_cblock(cblock), cache->dirty_bitset)) {
495 cache->nr_dirty = to_cblock(from_cblock(cache->nr_dirty) + 1);
496 policy_set_dirty(cache->policy, oblock);
497 }
498}
499
500static void clear_dirty(struct cache *cache, dm_oblock_t oblock, dm_cblock_t cblock)
501{
502 if (test_and_clear_bit(from_cblock(cblock), cache->dirty_bitset)) {
503 policy_clear_dirty(cache->policy, oblock);
504 cache->nr_dirty = to_cblock(from_cblock(cache->nr_dirty) - 1);
505 if (!from_cblock(cache->nr_dirty))
506 dm_table_event(cache->ti->table);
507 }
508}
509
510/*----------------------------------------------------------------*/
511
512static bool block_size_is_power_of_two(struct cache *cache)
513{
514 return cache->sectors_per_block_shift >= 0;
515}
516
517/* gcc on ARM generates spurious references to __udivdi3 and __umoddi3 */
518#if defined(CONFIG_ARM) && __GNUC__ == 4 && __GNUC_MINOR__ <= 6
519__always_inline
520#endif
521static dm_block_t block_div(dm_block_t b, uint32_t n)
522{
523 do_div(b, n);
524
525 return b;
526}
527
528static void set_discard(struct cache *cache, dm_oblock_t b)
529{
530 unsigned long flags;
531
532 atomic_inc(&cache->stats.discard_count);
533
534 spin_lock_irqsave(&cache->lock, flags);
535 set_bit(from_oblock(b), cache->discard_bitset);
536 spin_unlock_irqrestore(&cache->lock, flags);
537}
538
539static void clear_discard(struct cache *cache, dm_oblock_t b)
540{
541 unsigned long flags;
542
543 spin_lock_irqsave(&cache->lock, flags);
544 clear_bit(from_oblock(b), cache->discard_bitset);
545 spin_unlock_irqrestore(&cache->lock, flags);
546}
547
548static bool is_discarded(struct cache *cache, dm_oblock_t b)
549{
550 int r;
551 unsigned long flags;
552
553 spin_lock_irqsave(&cache->lock, flags);
554 r = test_bit(from_oblock(b), cache->discard_bitset);
555 spin_unlock_irqrestore(&cache->lock, flags);
556
557 return r;
558}
559
560static bool is_discarded_oblock(struct cache *cache, dm_oblock_t b)
561{
562 int r;
563 unsigned long flags;
564
565 spin_lock_irqsave(&cache->lock, flags);
566 r = test_bit(from_oblock(b), cache->discard_bitset);
567 spin_unlock_irqrestore(&cache->lock, flags);
568
569 return r;
570}
571
572/*----------------------------------------------------------------*/
573
574static void load_stats(struct cache *cache)
575{
576 struct dm_cache_statistics stats;
577
578 dm_cache_metadata_get_stats(cache->cmd, &stats);
579 atomic_set(&cache->stats.read_hit, stats.read_hits);
580 atomic_set(&cache->stats.read_miss, stats.read_misses);
581 atomic_set(&cache->stats.write_hit, stats.write_hits);
582 atomic_set(&cache->stats.write_miss, stats.write_misses);
583}
584
585static void save_stats(struct cache *cache)
586{
587 struct dm_cache_statistics stats;
588
589 stats.read_hits = atomic_read(&cache->stats.read_hit);
590 stats.read_misses = atomic_read(&cache->stats.read_miss);
591 stats.write_hits = atomic_read(&cache->stats.write_hit);
592 stats.write_misses = atomic_read(&cache->stats.write_miss);
593
594 dm_cache_metadata_set_stats(cache->cmd, &stats);
595}
596
597/*----------------------------------------------------------------
598 * Per bio data
599 *--------------------------------------------------------------*/
600
601/*
602 * If using writeback, leave out struct per_bio_data's writethrough fields.
603 */
604#define PB_DATA_SIZE_WB (offsetof(struct per_bio_data, cache))
605#define PB_DATA_SIZE_WT (sizeof(struct per_bio_data))
606
607static bool writethrough_mode(struct cache_features *f)
608{
609 return f->io_mode == CM_IO_WRITETHROUGH;
610}
611
612static bool writeback_mode(struct cache_features *f)
613{
614 return f->io_mode == CM_IO_WRITEBACK;
615}
616
617static bool passthrough_mode(struct cache_features *f)
618{
619 return f->io_mode == CM_IO_PASSTHROUGH;
620}
621
622static size_t get_per_bio_data_size(struct cache *cache)
623{
624 return writethrough_mode(&cache->features) ? PB_DATA_SIZE_WT : PB_DATA_SIZE_WB;
625}
626
627static struct per_bio_data *get_per_bio_data(struct bio *bio, size_t data_size)
628{
629 struct per_bio_data *pb = dm_per_bio_data(bio, data_size);
630 BUG_ON(!pb);
631 return pb;
632}
633
634static struct per_bio_data *init_per_bio_data(struct bio *bio, size_t data_size)
635{
636 struct per_bio_data *pb = get_per_bio_data(bio, data_size);
637
638 pb->tick = false;
639 pb->req_nr = dm_bio_get_target_bio_nr(bio);
640 pb->all_io_entry = NULL;
641
642 return pb;
643}
644
645/*----------------------------------------------------------------
646 * Remapping
647 *--------------------------------------------------------------*/
648static void remap_to_origin(struct cache *cache, struct bio *bio)
649{
650 bio->bi_bdev = cache->origin_dev->bdev;
651}
652
653static void remap_to_cache(struct cache *cache, struct bio *bio,
654 dm_cblock_t cblock)
655{
656 sector_t bi_sector = bio->bi_iter.bi_sector;
657 sector_t block = from_cblock(cblock);
658
659 bio->bi_bdev = cache->cache_dev->bdev;
660 if (!block_size_is_power_of_two(cache))
661 bio->bi_iter.bi_sector =
662 (block * cache->sectors_per_block) +
663 sector_div(bi_sector, cache->sectors_per_block);
664 else
665 bio->bi_iter.bi_sector =
666 (block << cache->sectors_per_block_shift) |
667 (bi_sector & (cache->sectors_per_block - 1));
668}
669
670static void check_if_tick_bio_needed(struct cache *cache, struct bio *bio)
671{
672 unsigned long flags;
673 size_t pb_data_size = get_per_bio_data_size(cache);
674 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
675
676 spin_lock_irqsave(&cache->lock, flags);
677 if (cache->need_tick_bio &&
678 !(bio->bi_rw & (REQ_FUA | REQ_FLUSH | REQ_DISCARD))) {
679 pb->tick = true;
680 cache->need_tick_bio = false;
681 }
682 spin_unlock_irqrestore(&cache->lock, flags);
683}
684
685static void remap_to_origin_clear_discard(struct cache *cache, struct bio *bio,
686 dm_oblock_t oblock)
687{
688 check_if_tick_bio_needed(cache, bio);
689 remap_to_origin(cache, bio);
690 if (bio_data_dir(bio) == WRITE)
691 clear_discard(cache, oblock);
692}
693
694static void remap_to_cache_dirty(struct cache *cache, struct bio *bio,
695 dm_oblock_t oblock, dm_cblock_t cblock)
696{
697 check_if_tick_bio_needed(cache, bio);
698 remap_to_cache(cache, bio, cblock);
699 if (bio_data_dir(bio) == WRITE) {
700 set_dirty(cache, oblock, cblock);
701 clear_discard(cache, oblock);
702 }
703}
704
705static dm_oblock_t get_bio_block(struct cache *cache, struct bio *bio)
706{
707 sector_t block_nr = bio->bi_iter.bi_sector;
708
709 if (!block_size_is_power_of_two(cache))
710 (void) sector_div(block_nr, cache->sectors_per_block);
711 else
712 block_nr >>= cache->sectors_per_block_shift;
713
714 return to_oblock(block_nr);
715}
716
717static int bio_triggers_commit(struct cache *cache, struct bio *bio)
718{
719 return bio->bi_rw & (REQ_FLUSH | REQ_FUA);
720}
721
722static void issue(struct cache *cache, struct bio *bio)
723{
724 unsigned long flags;
725
726 if (!bio_triggers_commit(cache, bio)) {
727 generic_make_request(bio);
728 return;
729 }
730
731 /*
732 * Batch together any bios that trigger commits and then issue a
733 * single commit for them in do_worker().
734 */
735 spin_lock_irqsave(&cache->lock, flags);
736 cache->commit_requested = true;
737 bio_list_add(&cache->deferred_flush_bios, bio);
738 spin_unlock_irqrestore(&cache->lock, flags);
739}
740
741static void defer_writethrough_bio(struct cache *cache, struct bio *bio)
742{
743 unsigned long flags;
744
745 spin_lock_irqsave(&cache->lock, flags);
746 bio_list_add(&cache->deferred_writethrough_bios, bio);
747 spin_unlock_irqrestore(&cache->lock, flags);
748
749 wake_worker(cache);
750}
751
752static void writethrough_endio(struct bio *bio, int err)
753{
754 struct per_bio_data *pb = get_per_bio_data(bio, PB_DATA_SIZE_WT);
755
756 dm_unhook_bio(&pb->hook_info, bio);
757
758 if (err) {
759 bio_endio(bio, err);
760 return;
761 }
762
763 dm_bio_restore(&pb->bio_details, bio);
764 remap_to_cache(pb->cache, bio, pb->cblock);
765
766 /*
767 * We can't issue this bio directly, since we're in interrupt
768 * context. So it gets put on a bio list for processing by the
769 * worker thread.
770 */
771 defer_writethrough_bio(pb->cache, bio);
772}
773
774/*
775 * When running in writethrough mode we need to send writes to clean blocks
776 * to both the cache and origin devices. In future we'd like to clone the
777 * bio and send them in parallel, but for now we're doing them in
778 * series as this is easier.
779 */
780static void remap_to_origin_then_cache(struct cache *cache, struct bio *bio,
781 dm_oblock_t oblock, dm_cblock_t cblock)
782{
783 struct per_bio_data *pb = get_per_bio_data(bio, PB_DATA_SIZE_WT);
784
785 pb->cache = cache;
786 pb->cblock = cblock;
787 dm_hook_bio(&pb->hook_info, bio, writethrough_endio, NULL);
788 dm_bio_record(&pb->bio_details, bio);
789
790 remap_to_origin_clear_discard(pb->cache, bio, oblock);
791}
792
793/*----------------------------------------------------------------
794 * Migration processing
795 *
796 * Migration covers moving data from the origin device to the cache, or
797 * vice versa.
798 *--------------------------------------------------------------*/
799static void free_migration(struct dm_cache_migration *mg)
800{
801 mempool_free(mg, mg->cache->migration_pool);
802}
803
804static void inc_nr_migrations(struct cache *cache)
805{
806 atomic_inc(&cache->nr_migrations);
807}
808
809static void dec_nr_migrations(struct cache *cache)
810{
811 atomic_dec(&cache->nr_migrations);
812
813 /*
814 * Wake the worker in case we're suspending the target.
815 */
816 wake_up(&cache->migration_wait);
817}
818
819static void __cell_defer(struct cache *cache, struct dm_bio_prison_cell *cell,
820 bool holder)
821{
822 (holder ? dm_cell_release : dm_cell_release_no_holder)
823 (cache->prison, cell, &cache->deferred_bios);
824 free_prison_cell(cache, cell);
825}
826
827static void cell_defer(struct cache *cache, struct dm_bio_prison_cell *cell,
828 bool holder)
829{
830 unsigned long flags;
831
832 spin_lock_irqsave(&cache->lock, flags);
833 __cell_defer(cache, cell, holder);
834 spin_unlock_irqrestore(&cache->lock, flags);
835
836 wake_worker(cache);
837}
838
839static void cleanup_migration(struct dm_cache_migration *mg)
840{
841 struct cache *cache = mg->cache;
842 free_migration(mg);
843 dec_nr_migrations(cache);
844}
845
846static void migration_failure(struct dm_cache_migration *mg)
847{
848 struct cache *cache = mg->cache;
849
850 if (mg->writeback) {
851 DMWARN_LIMIT("writeback failed; couldn't copy block");
852 set_dirty(cache, mg->old_oblock, mg->cblock);
853 cell_defer(cache, mg->old_ocell, false);
854
855 } else if (mg->demote) {
856 DMWARN_LIMIT("demotion failed; couldn't copy block");
857 policy_force_mapping(cache->policy, mg->new_oblock, mg->old_oblock);
858
859 cell_defer(cache, mg->old_ocell, mg->promote ? false : true);
860 if (mg->promote)
861 cell_defer(cache, mg->new_ocell, true);
862 } else {
863 DMWARN_LIMIT("promotion failed; couldn't copy block");
864 policy_remove_mapping(cache->policy, mg->new_oblock);
865 cell_defer(cache, mg->new_ocell, true);
866 }
867
868 cleanup_migration(mg);
869}
870
871static void migration_success_pre_commit(struct dm_cache_migration *mg)
872{
873 unsigned long flags;
874 struct cache *cache = mg->cache;
875
876 if (mg->writeback) {
877 cell_defer(cache, mg->old_ocell, false);
878 clear_dirty(cache, mg->old_oblock, mg->cblock);
879 cleanup_migration(mg);
880 return;
881
882 } else if (mg->demote) {
883 if (dm_cache_remove_mapping(cache->cmd, mg->cblock)) {
884 DMWARN_LIMIT("demotion failed; couldn't update on disk metadata");
885 policy_force_mapping(cache->policy, mg->new_oblock,
886 mg->old_oblock);
887 if (mg->promote)
888 cell_defer(cache, mg->new_ocell, true);
889 cleanup_migration(mg);
890 return;
891 }
892 } else {
893 if (dm_cache_insert_mapping(cache->cmd, mg->cblock, mg->new_oblock)) {
894 DMWARN_LIMIT("promotion failed; couldn't update on disk metadata");
895 policy_remove_mapping(cache->policy, mg->new_oblock);
896 cleanup_migration(mg);
897 return;
898 }
899 }
900
901 spin_lock_irqsave(&cache->lock, flags);
902 list_add_tail(&mg->list, &cache->need_commit_migrations);
903 cache->commit_requested = true;
904 spin_unlock_irqrestore(&cache->lock, flags);
905}
906
907static void migration_success_post_commit(struct dm_cache_migration *mg)
908{
909 unsigned long flags;
910 struct cache *cache = mg->cache;
911
912 if (mg->writeback) {
913 DMWARN("writeback unexpectedly triggered commit");
914 return;
915
916 } else if (mg->demote) {
917 cell_defer(cache, mg->old_ocell, mg->promote ? false : true);
918
919 if (mg->promote) {
920 mg->demote = false;
921
922 spin_lock_irqsave(&cache->lock, flags);
923 list_add_tail(&mg->list, &cache->quiesced_migrations);
924 spin_unlock_irqrestore(&cache->lock, flags);
925
926 } else {
927 if (mg->invalidate)
928 policy_remove_mapping(cache->policy, mg->old_oblock);
929 cleanup_migration(mg);
930 }
931
932 } else {
933 if (mg->requeue_holder)
934 cell_defer(cache, mg->new_ocell, true);
935 else {
936 bio_endio(mg->new_ocell->holder, 0);
937 cell_defer(cache, mg->new_ocell, false);
938 }
939 clear_dirty(cache, mg->new_oblock, mg->cblock);
940 cleanup_migration(mg);
941 }
942}
943
944static void copy_complete(int read_err, unsigned long write_err, void *context)
945{
946 unsigned long flags;
947 struct dm_cache_migration *mg = (struct dm_cache_migration *) context;
948 struct cache *cache = mg->cache;
949
950 if (read_err || write_err)
951 mg->err = true;
952
953 spin_lock_irqsave(&cache->lock, flags);
954 list_add_tail(&mg->list, &cache->completed_migrations);
955 spin_unlock_irqrestore(&cache->lock, flags);
956
957 wake_worker(cache);
958}
959
960static void issue_copy_real(struct dm_cache_migration *mg)
961{
962 int r;
963 struct dm_io_region o_region, c_region;
964 struct cache *cache = mg->cache;
965 sector_t cblock = from_cblock(mg->cblock);
966
967 o_region.bdev = cache->origin_dev->bdev;
968 o_region.count = cache->sectors_per_block;
969
970 c_region.bdev = cache->cache_dev->bdev;
971 c_region.sector = cblock * cache->sectors_per_block;
972 c_region.count = cache->sectors_per_block;
973
974 if (mg->writeback || mg->demote) {
975 /* demote */
976 o_region.sector = from_oblock(mg->old_oblock) * cache->sectors_per_block;
977 r = dm_kcopyd_copy(cache->copier, &c_region, 1, &o_region, 0, copy_complete, mg);
978 } else {
979 /* promote */
980 o_region.sector = from_oblock(mg->new_oblock) * cache->sectors_per_block;
981 r = dm_kcopyd_copy(cache->copier, &o_region, 1, &c_region, 0, copy_complete, mg);
982 }
983
984 if (r < 0) {
985 DMERR_LIMIT("issuing migration failed");
986 migration_failure(mg);
987 }
988}
989
990static void overwrite_endio(struct bio *bio, int err)
991{
992 struct dm_cache_migration *mg = bio->bi_private;
993 struct cache *cache = mg->cache;
994 size_t pb_data_size = get_per_bio_data_size(cache);
995 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
996 unsigned long flags;
997
998 dm_unhook_bio(&pb->hook_info, bio);
999
1000 if (err)
1001 mg->err = true;
1002
1003 mg->requeue_holder = false;
1004
1005 spin_lock_irqsave(&cache->lock, flags);
1006 list_add_tail(&mg->list, &cache->completed_migrations);
1007 spin_unlock_irqrestore(&cache->lock, flags);
1008
1009 wake_worker(cache);
1010}
1011
1012static void issue_overwrite(struct dm_cache_migration *mg, struct bio *bio)
1013{
1014 size_t pb_data_size = get_per_bio_data_size(mg->cache);
1015 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
1016
1017 dm_hook_bio(&pb->hook_info, bio, overwrite_endio, mg);
1018 remap_to_cache_dirty(mg->cache, bio, mg->new_oblock, mg->cblock);
1019 generic_make_request(bio);
1020}
1021
1022static bool bio_writes_complete_block(struct cache *cache, struct bio *bio)
1023{
1024 return (bio_data_dir(bio) == WRITE) &&
1025 (bio->bi_iter.bi_size == (cache->sectors_per_block << SECTOR_SHIFT));
1026}
1027
1028static void avoid_copy(struct dm_cache_migration *mg)
1029{
1030 atomic_inc(&mg->cache->stats.copies_avoided);
1031 migration_success_pre_commit(mg);
1032}
1033
1034static void issue_copy(struct dm_cache_migration *mg)
1035{
1036 bool avoid;
1037 struct cache *cache = mg->cache;
1038
1039 if (mg->writeback || mg->demote)
1040 avoid = !is_dirty(cache, mg->cblock) ||
1041 is_discarded_oblock(cache, mg->old_oblock);
1042 else {
1043 struct bio *bio = mg->new_ocell->holder;
1044
1045 avoid = is_discarded_oblock(cache, mg->new_oblock);
1046
1047 if (!avoid && bio_writes_complete_block(cache, bio)) {
1048 issue_overwrite(mg, bio);
1049 return;
1050 }
1051 }
1052
1053 avoid ? avoid_copy(mg) : issue_copy_real(mg);
1054}
1055
1056static void complete_migration(struct dm_cache_migration *mg)
1057{
1058 if (mg->err)
1059 migration_failure(mg);
1060 else
1061 migration_success_pre_commit(mg);
1062}
1063
1064static void process_migrations(struct cache *cache, struct list_head *head,
1065 void (*fn)(struct dm_cache_migration *))
1066{
1067 unsigned long flags;
1068 struct list_head list;
1069 struct dm_cache_migration *mg, *tmp;
1070
1071 INIT_LIST_HEAD(&list);
1072 spin_lock_irqsave(&cache->lock, flags);
1073 list_splice_init(head, &list);
1074 spin_unlock_irqrestore(&cache->lock, flags);
1075
1076 list_for_each_entry_safe(mg, tmp, &list, list)
1077 fn(mg);
1078}
1079
1080static void __queue_quiesced_migration(struct dm_cache_migration *mg)
1081{
1082 list_add_tail(&mg->list, &mg->cache->quiesced_migrations);
1083}
1084
1085static void queue_quiesced_migration(struct dm_cache_migration *mg)
1086{
1087 unsigned long flags;
1088 struct cache *cache = mg->cache;
1089
1090 spin_lock_irqsave(&cache->lock, flags);
1091 __queue_quiesced_migration(mg);
1092 spin_unlock_irqrestore(&cache->lock, flags);
1093
1094 wake_worker(cache);
1095}
1096
1097static void queue_quiesced_migrations(struct cache *cache, struct list_head *work)
1098{
1099 unsigned long flags;
1100 struct dm_cache_migration *mg, *tmp;
1101
1102 spin_lock_irqsave(&cache->lock, flags);
1103 list_for_each_entry_safe(mg, tmp, work, list)
1104 __queue_quiesced_migration(mg);
1105 spin_unlock_irqrestore(&cache->lock, flags);
1106
1107 wake_worker(cache);
1108}
1109
1110static void check_for_quiesced_migrations(struct cache *cache,
1111 struct per_bio_data *pb)
1112{
1113 struct list_head work;
1114
1115 if (!pb->all_io_entry)
1116 return;
1117
1118 INIT_LIST_HEAD(&work);
1119 if (pb->all_io_entry)
1120 dm_deferred_entry_dec(pb->all_io_entry, &work);
1121
1122 if (!list_empty(&work))
1123 queue_quiesced_migrations(cache, &work);
1124}
1125
1126static void quiesce_migration(struct dm_cache_migration *mg)
1127{
1128 if (!dm_deferred_set_add_work(mg->cache->all_io_ds, &mg->list))
1129 queue_quiesced_migration(mg);
1130}
1131
1132static void promote(struct cache *cache, struct prealloc *structs,
1133 dm_oblock_t oblock, dm_cblock_t cblock,
1134 struct dm_bio_prison_cell *cell)
1135{
1136 struct dm_cache_migration *mg = prealloc_get_migration(structs);
1137
1138 mg->err = false;
1139 mg->writeback = false;
1140 mg->demote = false;
1141 mg->promote = true;
1142 mg->requeue_holder = true;
1143 mg->invalidate = false;
1144 mg->cache = cache;
1145 mg->new_oblock = oblock;
1146 mg->cblock = cblock;
1147 mg->old_ocell = NULL;
1148 mg->new_ocell = cell;
1149 mg->start_jiffies = jiffies;
1150
1151 inc_nr_migrations(cache);
1152 quiesce_migration(mg);
1153}
1154
1155static void writeback(struct cache *cache, struct prealloc *structs,
1156 dm_oblock_t oblock, dm_cblock_t cblock,
1157 struct dm_bio_prison_cell *cell)
1158{
1159 struct dm_cache_migration *mg = prealloc_get_migration(structs);
1160
1161 mg->err = false;
1162 mg->writeback = true;
1163 mg->demote = false;
1164 mg->promote = false;
1165 mg->requeue_holder = true;
1166 mg->invalidate = false;
1167 mg->cache = cache;
1168 mg->old_oblock = oblock;
1169 mg->cblock = cblock;
1170 mg->old_ocell = cell;
1171 mg->new_ocell = NULL;
1172 mg->start_jiffies = jiffies;
1173
1174 inc_nr_migrations(cache);
1175 quiesce_migration(mg);
1176}
1177
1178static void demote_then_promote(struct cache *cache, struct prealloc *structs,
1179 dm_oblock_t old_oblock, dm_oblock_t new_oblock,
1180 dm_cblock_t cblock,
1181 struct dm_bio_prison_cell *old_ocell,
1182 struct dm_bio_prison_cell *new_ocell)
1183{
1184 struct dm_cache_migration *mg = prealloc_get_migration(structs);
1185
1186 mg->err = false;
1187 mg->writeback = false;
1188 mg->demote = true;
1189 mg->promote = true;
1190 mg->requeue_holder = true;
1191 mg->invalidate = false;
1192 mg->cache = cache;
1193 mg->old_oblock = old_oblock;
1194 mg->new_oblock = new_oblock;
1195 mg->cblock = cblock;
1196 mg->old_ocell = old_ocell;
1197 mg->new_ocell = new_ocell;
1198 mg->start_jiffies = jiffies;
1199
1200 inc_nr_migrations(cache);
1201 quiesce_migration(mg);
1202}
1203
1204/*
1205 * Invalidate a cache entry. No writeback occurs; any changes in the cache
1206 * block are thrown away.
1207 */
1208static void invalidate(struct cache *cache, struct prealloc *structs,
1209 dm_oblock_t oblock, dm_cblock_t cblock,
1210 struct dm_bio_prison_cell *cell)
1211{
1212 struct dm_cache_migration *mg = prealloc_get_migration(structs);
1213
1214 mg->err = false;
1215 mg->writeback = false;
1216 mg->demote = true;
1217 mg->promote = false;
1218 mg->requeue_holder = true;
1219 mg->invalidate = true;
1220 mg->cache = cache;
1221 mg->old_oblock = oblock;
1222 mg->cblock = cblock;
1223 mg->old_ocell = cell;
1224 mg->new_ocell = NULL;
1225 mg->start_jiffies = jiffies;
1226
1227 inc_nr_migrations(cache);
1228 quiesce_migration(mg);
1229}
1230
1231/*----------------------------------------------------------------
1232 * bio processing
1233 *--------------------------------------------------------------*/
1234static void defer_bio(struct cache *cache, struct bio *bio)
1235{
1236 unsigned long flags;
1237
1238 spin_lock_irqsave(&cache->lock, flags);
1239 bio_list_add(&cache->deferred_bios, bio);
1240 spin_unlock_irqrestore(&cache->lock, flags);
1241
1242 wake_worker(cache);
1243}
1244
1245static void process_flush_bio(struct cache *cache, struct bio *bio)
1246{
1247 size_t pb_data_size = get_per_bio_data_size(cache);
1248 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
1249
1250 BUG_ON(bio->bi_iter.bi_size);
1251 if (!pb->req_nr)
1252 remap_to_origin(cache, bio);
1253 else
1254 remap_to_cache(cache, bio, 0);
1255
1256 issue(cache, bio);
1257}
1258
1259/*
1260 * People generally discard large parts of a device, eg, the whole device
1261 * when formatting. Splitting these large discards up into cache block
1262 * sized ios and then quiescing (always neccessary for discard) takes too
1263 * long.
1264 *
1265 * We keep it simple, and allow any size of discard to come in, and just
1266 * mark off blocks on the discard bitset. No passdown occurs!
1267 *
1268 * To implement passdown we need to change the bio_prison such that a cell
1269 * can have a key that spans many blocks.
1270 */
1271static void process_discard_bio(struct cache *cache, struct bio *bio)
1272{
1273 dm_block_t start_block = dm_sector_div_up(bio->bi_iter.bi_sector,
1274 cache->sectors_per_block);
1275 dm_block_t end_block = bio_end_sector(bio);
1276 dm_block_t b;
1277
1278 end_block = block_div(end_block, cache->sectors_per_block);
1279
1280 for (b = start_block; b < end_block; b++)
1281 set_discard(cache, to_oblock(b));
1282
1283 bio_endio(bio, 0);
1284}
1285
1286static bool spare_migration_bandwidth(struct cache *cache)
1287{
1288 sector_t current_volume = (atomic_read(&cache->nr_migrations) + 1) *
1289 cache->sectors_per_block;
1290 return current_volume < cache->migration_threshold;
1291}
1292
1293static void inc_hit_counter(struct cache *cache, struct bio *bio)
1294{
1295 atomic_inc(bio_data_dir(bio) == READ ?
1296 &cache->stats.read_hit : &cache->stats.write_hit);
1297}
1298
1299static void inc_miss_counter(struct cache *cache, struct bio *bio)
1300{
1301 atomic_inc(bio_data_dir(bio) == READ ?
1302 &cache->stats.read_miss : &cache->stats.write_miss);
1303}
1304
1305static void issue_cache_bio(struct cache *cache, struct bio *bio,
1306 struct per_bio_data *pb,
1307 dm_oblock_t oblock, dm_cblock_t cblock)
1308{
1309 pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
1310 remap_to_cache_dirty(cache, bio, oblock, cblock);
1311 issue(cache, bio);
1312}
1313
1314static void process_bio(struct cache *cache, struct prealloc *structs,
1315 struct bio *bio)
1316{
1317 int r;
1318 bool release_cell = true;
1319 dm_oblock_t block = get_bio_block(cache, bio);
1320 struct dm_bio_prison_cell *cell_prealloc, *old_ocell, *new_ocell;
1321 struct policy_result lookup_result;
1322 size_t pb_data_size = get_per_bio_data_size(cache);
1323 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
1324 bool discarded_block = is_discarded_oblock(cache, block);
1325 bool passthrough = passthrough_mode(&cache->features);
1326 bool can_migrate = !passthrough && (discarded_block || spare_migration_bandwidth(cache));
1327
1328 /*
1329 * Check to see if that block is currently migrating.
1330 */
1331 cell_prealloc = prealloc_get_cell(structs);
1332 r = bio_detain(cache, block, bio, cell_prealloc,
1333 (cell_free_fn) prealloc_put_cell,
1334 structs, &new_ocell);
1335 if (r > 0)
1336 return;
1337
1338 r = policy_map(cache->policy, block, true, can_migrate, discarded_block,
1339 bio, &lookup_result);
1340
1341 if (r == -EWOULDBLOCK)
1342 /* migration has been denied */
1343 lookup_result.op = POLICY_MISS;
1344
1345 switch (lookup_result.op) {
1346 case POLICY_HIT:
1347 if (passthrough) {
1348 inc_miss_counter(cache, bio);
1349
1350 /*
1351 * Passthrough always maps to the origin,
1352 * invalidating any cache blocks that are written
1353 * to.
1354 */
1355
1356 if (bio_data_dir(bio) == WRITE) {
1357 atomic_inc(&cache->stats.demotion);
1358 invalidate(cache, structs, block, lookup_result.cblock, new_ocell);
1359 release_cell = false;
1360
1361 } else {
1362 /* FIXME: factor out issue_origin() */
1363 pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
1364 remap_to_origin_clear_discard(cache, bio, block);
1365 issue(cache, bio);
1366 }
1367 } else {
1368 inc_hit_counter(cache, bio);
1369
1370 if (bio_data_dir(bio) == WRITE &&
1371 writethrough_mode(&cache->features) &&
1372 !is_dirty(cache, lookup_result.cblock)) {
1373 pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
1374 remap_to_origin_then_cache(cache, bio, block, lookup_result.cblock);
1375 issue(cache, bio);
1376 } else
1377 issue_cache_bio(cache, bio, pb, block, lookup_result.cblock);
1378 }
1379
1380 break;
1381
1382 case POLICY_MISS:
1383 inc_miss_counter(cache, bio);
1384 pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
1385 remap_to_origin_clear_discard(cache, bio, block);
1386 issue(cache, bio);
1387 break;
1388
1389 case POLICY_NEW:
1390 atomic_inc(&cache->stats.promotion);
1391 promote(cache, structs, block, lookup_result.cblock, new_ocell);
1392 release_cell = false;
1393 break;
1394
1395 case POLICY_REPLACE:
1396 cell_prealloc = prealloc_get_cell(structs);
1397 r = bio_detain(cache, lookup_result.old_oblock, bio, cell_prealloc,
1398 (cell_free_fn) prealloc_put_cell,
1399 structs, &old_ocell);
1400 if (r > 0) {
1401 /*
1402 * We have to be careful to avoid lock inversion of
1403 * the cells. So we back off, and wait for the
1404 * old_ocell to become free.
1405 */
1406 policy_force_mapping(cache->policy, block,
1407 lookup_result.old_oblock);
1408 atomic_inc(&cache->stats.cache_cell_clash);
1409 break;
1410 }
1411 atomic_inc(&cache->stats.demotion);
1412 atomic_inc(&cache->stats.promotion);
1413
1414 demote_then_promote(cache, structs, lookup_result.old_oblock,
1415 block, lookup_result.cblock,
1416 old_ocell, new_ocell);
1417 release_cell = false;
1418 break;
1419
1420 default:
1421 DMERR_LIMIT("%s: erroring bio, unknown policy op: %u", __func__,
1422 (unsigned) lookup_result.op);
1423 bio_io_error(bio);
1424 }
1425
1426 if (release_cell)
1427 cell_defer(cache, new_ocell, false);
1428}
1429
1430static int need_commit_due_to_time(struct cache *cache)
1431{
1432 return jiffies < cache->last_commit_jiffies ||
1433 jiffies > cache->last_commit_jiffies + COMMIT_PERIOD;
1434}
1435
1436static int commit_if_needed(struct cache *cache)
1437{
1438 int r = 0;
1439
1440 if ((cache->commit_requested || need_commit_due_to_time(cache)) &&
1441 dm_cache_changed_this_transaction(cache->cmd)) {
1442 atomic_inc(&cache->stats.commit_count);
1443 cache->commit_requested = false;
1444 r = dm_cache_commit(cache->cmd, false);
1445 cache->last_commit_jiffies = jiffies;
1446 }
1447
1448 return r;
1449}
1450
1451static void process_deferred_bios(struct cache *cache)
1452{
1453 unsigned long flags;
1454 struct bio_list bios;
1455 struct bio *bio;
1456 struct prealloc structs;
1457
1458 memset(&structs, 0, sizeof(structs));
1459 bio_list_init(&bios);
1460
1461 spin_lock_irqsave(&cache->lock, flags);
1462 bio_list_merge(&bios, &cache->deferred_bios);
1463 bio_list_init(&cache->deferred_bios);
1464 spin_unlock_irqrestore(&cache->lock, flags);
1465
1466 while (!bio_list_empty(&bios)) {
1467 /*
1468 * If we've got no free migration structs, and processing
1469 * this bio might require one, we pause until there are some
1470 * prepared mappings to process.
1471 */
1472 if (prealloc_data_structs(cache, &structs)) {
1473 spin_lock_irqsave(&cache->lock, flags);
1474 bio_list_merge(&cache->deferred_bios, &bios);
1475 spin_unlock_irqrestore(&cache->lock, flags);
1476 break;
1477 }
1478
1479 bio = bio_list_pop(&bios);
1480
1481 if (bio->bi_rw & REQ_FLUSH)
1482 process_flush_bio(cache, bio);
1483 else if (bio->bi_rw & REQ_DISCARD)
1484 process_discard_bio(cache, bio);
1485 else
1486 process_bio(cache, &structs, bio);
1487 }
1488
1489 prealloc_free_structs(cache, &structs);
1490}
1491
1492static void process_deferred_flush_bios(struct cache *cache, bool submit_bios)
1493{
1494 unsigned long flags;
1495 struct bio_list bios;
1496 struct bio *bio;
1497
1498 bio_list_init(&bios);
1499
1500 spin_lock_irqsave(&cache->lock, flags);
1501 bio_list_merge(&bios, &cache->deferred_flush_bios);
1502 bio_list_init(&cache->deferred_flush_bios);
1503 spin_unlock_irqrestore(&cache->lock, flags);
1504
1505 while ((bio = bio_list_pop(&bios)))
1506 submit_bios ? generic_make_request(bio) : bio_io_error(bio);
1507}
1508
1509static void process_deferred_writethrough_bios(struct cache *cache)
1510{
1511 unsigned long flags;
1512 struct bio_list bios;
1513 struct bio *bio;
1514
1515 bio_list_init(&bios);
1516
1517 spin_lock_irqsave(&cache->lock, flags);
1518 bio_list_merge(&bios, &cache->deferred_writethrough_bios);
1519 bio_list_init(&cache->deferred_writethrough_bios);
1520 spin_unlock_irqrestore(&cache->lock, flags);
1521
1522 while ((bio = bio_list_pop(&bios)))
1523 generic_make_request(bio);
1524}
1525
1526static void writeback_some_dirty_blocks(struct cache *cache)
1527{
1528 int r = 0;
1529 dm_oblock_t oblock;
1530 dm_cblock_t cblock;
1531 struct prealloc structs;
1532 struct dm_bio_prison_cell *old_ocell;
1533
1534 memset(&structs, 0, sizeof(structs));
1535
1536 while (spare_migration_bandwidth(cache)) {
1537 if (prealloc_data_structs(cache, &structs))
1538 break;
1539
1540 r = policy_writeback_work(cache->policy, &oblock, &cblock);
1541 if (r)
1542 break;
1543
1544 r = get_cell(cache, oblock, &structs, &old_ocell);
1545 if (r) {
1546 policy_set_dirty(cache->policy, oblock);
1547 break;
1548 }
1549
1550 writeback(cache, &structs, oblock, cblock, old_ocell);
1551 }
1552
1553 prealloc_free_structs(cache, &structs);
1554}
1555
1556/*----------------------------------------------------------------
1557 * Invalidations.
1558 * Dropping something from the cache *without* writing back.
1559 *--------------------------------------------------------------*/
1560
1561static void process_invalidation_request(struct cache *cache, struct invalidation_request *req)
1562{
1563 int r = 0;
1564 uint64_t begin = from_cblock(req->cblocks->begin);
1565 uint64_t end = from_cblock(req->cblocks->end);
1566
1567 while (begin != end) {
1568 r = policy_remove_cblock(cache->policy, to_cblock(begin));
1569 if (!r) {
1570 r = dm_cache_remove_mapping(cache->cmd, to_cblock(begin));
1571 if (r)
1572 break;
1573
1574 } else if (r == -ENODATA) {
1575 /* harmless, already unmapped */
1576 r = 0;
1577
1578 } else {
1579 DMERR("policy_remove_cblock failed");
1580 break;
1581 }
1582
1583 begin++;
1584 }
1585
1586 cache->commit_requested = true;
1587
1588 req->err = r;
1589 atomic_set(&req->complete, 1);
1590
1591 wake_up(&req->result_wait);
1592}
1593
1594static void process_invalidation_requests(struct cache *cache)
1595{
1596 struct list_head list;
1597 struct invalidation_request *req, *tmp;
1598
1599 INIT_LIST_HEAD(&list);
1600 spin_lock(&cache->invalidation_lock);
1601 list_splice_init(&cache->invalidation_requests, &list);
1602 spin_unlock(&cache->invalidation_lock);
1603
1604 list_for_each_entry_safe (req, tmp, &list, list)
1605 process_invalidation_request(cache, req);
1606}
1607
1608/*----------------------------------------------------------------
1609 * Main worker loop
1610 *--------------------------------------------------------------*/
1611static bool is_quiescing(struct cache *cache)
1612{
1613 return atomic_read(&cache->quiescing);
1614}
1615
1616static void ack_quiescing(struct cache *cache)
1617{
1618 if (is_quiescing(cache)) {
1619 atomic_inc(&cache->quiescing_ack);
1620 wake_up(&cache->quiescing_wait);
1621 }
1622}
1623
1624static void wait_for_quiescing_ack(struct cache *cache)
1625{
1626 wait_event(cache->quiescing_wait, atomic_read(&cache->quiescing_ack));
1627}
1628
1629static void start_quiescing(struct cache *cache)
1630{
1631 atomic_inc(&cache->quiescing);
1632 wait_for_quiescing_ack(cache);
1633}
1634
1635static void stop_quiescing(struct cache *cache)
1636{
1637 atomic_set(&cache->quiescing, 0);
1638 atomic_set(&cache->quiescing_ack, 0);
1639}
1640
1641static void wait_for_migrations(struct cache *cache)
1642{
1643 wait_event(cache->migration_wait, !atomic_read(&cache->nr_migrations));
1644}
1645
1646static void stop_worker(struct cache *cache)
1647{
1648 cancel_delayed_work(&cache->waker);
1649 flush_workqueue(cache->wq);
1650}
1651
1652static void requeue_deferred_io(struct cache *cache)
1653{
1654 struct bio *bio;
1655 struct bio_list bios;
1656
1657 bio_list_init(&bios);
1658 bio_list_merge(&bios, &cache->deferred_bios);
1659 bio_list_init(&cache->deferred_bios);
1660
1661 while ((bio = bio_list_pop(&bios)))
1662 bio_endio(bio, DM_ENDIO_REQUEUE);
1663}
1664
1665static int more_work(struct cache *cache)
1666{
1667 if (is_quiescing(cache))
1668 return !list_empty(&cache->quiesced_migrations) ||
1669 !list_empty(&cache->completed_migrations) ||
1670 !list_empty(&cache->need_commit_migrations);
1671 else
1672 return !bio_list_empty(&cache->deferred_bios) ||
1673 !bio_list_empty(&cache->deferred_flush_bios) ||
1674 !bio_list_empty(&cache->deferred_writethrough_bios) ||
1675 !list_empty(&cache->quiesced_migrations) ||
1676 !list_empty(&cache->completed_migrations) ||
1677 !list_empty(&cache->need_commit_migrations) ||
1678 cache->invalidate;
1679}
1680
1681static void do_worker(struct work_struct *ws)
1682{
1683 struct cache *cache = container_of(ws, struct cache, worker);
1684
1685 do {
1686 if (!is_quiescing(cache)) {
1687 writeback_some_dirty_blocks(cache);
1688 process_deferred_writethrough_bios(cache);
1689 process_deferred_bios(cache);
1690 process_invalidation_requests(cache);
1691 }
1692
1693 process_migrations(cache, &cache->quiesced_migrations, issue_copy);
1694 process_migrations(cache, &cache->completed_migrations, complete_migration);
1695
1696 if (commit_if_needed(cache)) {
1697 process_deferred_flush_bios(cache, false);
1698
1699 /*
1700 * FIXME: rollback metadata or just go into a
1701 * failure mode and error everything
1702 */
1703 } else {
1704 process_deferred_flush_bios(cache, true);
1705 process_migrations(cache, &cache->need_commit_migrations,
1706 migration_success_post_commit);
1707 }
1708
1709 ack_quiescing(cache);
1710
1711 } while (more_work(cache));
1712}
1713
1714/*
1715 * We want to commit periodically so that not too much
1716 * unwritten metadata builds up.
1717 */
1718static void do_waker(struct work_struct *ws)
1719{
1720 struct cache *cache = container_of(to_delayed_work(ws), struct cache, waker);
1721 policy_tick(cache->policy);
1722 wake_worker(cache);
1723 queue_delayed_work(cache->wq, &cache->waker, COMMIT_PERIOD);
1724}
1725
1726/*----------------------------------------------------------------*/
1727
1728static int is_congested(struct dm_dev *dev, int bdi_bits)
1729{
1730 struct request_queue *q = bdev_get_queue(dev->bdev);
1731 return bdi_congested(&q->backing_dev_info, bdi_bits);
1732}
1733
1734static int cache_is_congested(struct dm_target_callbacks *cb, int bdi_bits)
1735{
1736 struct cache *cache = container_of(cb, struct cache, callbacks);
1737
1738 return is_congested(cache->origin_dev, bdi_bits) ||
1739 is_congested(cache->cache_dev, bdi_bits);
1740}
1741
1742/*----------------------------------------------------------------
1743 * Target methods
1744 *--------------------------------------------------------------*/
1745
1746/*
1747 * This function gets called on the error paths of the constructor, so we
1748 * have to cope with a partially initialised struct.
1749 */
1750static void destroy(struct cache *cache)
1751{
1752 unsigned i;
1753
1754 if (cache->next_migration)
1755 mempool_free(cache->next_migration, cache->migration_pool);
1756
1757 if (cache->migration_pool)
1758 mempool_destroy(cache->migration_pool);
1759
1760 if (cache->all_io_ds)
1761 dm_deferred_set_destroy(cache->all_io_ds);
1762
1763 if (cache->prison)
1764 dm_bio_prison_destroy(cache->prison);
1765
1766 if (cache->wq)
1767 destroy_workqueue(cache->wq);
1768
1769 if (cache->dirty_bitset)
1770 free_bitset(cache->dirty_bitset);
1771
1772 if (cache->discard_bitset)
1773 free_bitset(cache->discard_bitset);
1774
1775 if (cache->copier)
1776 dm_kcopyd_client_destroy(cache->copier);
1777
1778 if (cache->cmd)
1779 dm_cache_metadata_close(cache->cmd);
1780
1781 if (cache->metadata_dev)
1782 dm_put_device(cache->ti, cache->metadata_dev);
1783
1784 if (cache->origin_dev)
1785 dm_put_device(cache->ti, cache->origin_dev);
1786
1787 if (cache->cache_dev)
1788 dm_put_device(cache->ti, cache->cache_dev);
1789
1790 if (cache->policy)
1791 dm_cache_policy_destroy(cache->policy);
1792
1793 for (i = 0; i < cache->nr_ctr_args ; i++)
1794 kfree(cache->ctr_args[i]);
1795 kfree(cache->ctr_args);
1796
1797 kfree(cache);
1798}
1799
1800static void cache_dtr(struct dm_target *ti)
1801{
1802 struct cache *cache = ti->private;
1803
1804 destroy(cache);
1805}
1806
1807static sector_t get_dev_size(struct dm_dev *dev)
1808{
1809 return i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT;
1810}
1811
1812/*----------------------------------------------------------------*/
1813
1814/*
1815 * Construct a cache device mapping.
1816 *
1817 * cache <metadata dev> <cache dev> <origin dev> <block size>
1818 * <#feature args> [<feature arg>]*
1819 * <policy> <#policy args> [<policy arg>]*
1820 *
1821 * metadata dev : fast device holding the persistent metadata
1822 * cache dev : fast device holding cached data blocks
1823 * origin dev : slow device holding original data blocks
1824 * block size : cache unit size in sectors
1825 *
1826 * #feature args : number of feature arguments passed
1827 * feature args : writethrough. (The default is writeback.)
1828 *
1829 * policy : the replacement policy to use
1830 * #policy args : an even number of policy arguments corresponding
1831 * to key/value pairs passed to the policy
1832 * policy args : key/value pairs passed to the policy
1833 * E.g. 'sequential_threshold 1024'
1834 * See cache-policies.txt for details.
1835 *
1836 * Optional feature arguments are:
1837 * writethrough : write through caching that prohibits cache block
1838 * content from being different from origin block content.
1839 * Without this argument, the default behaviour is to write
1840 * back cache block contents later for performance reasons,
1841 * so they may differ from the corresponding origin blocks.
1842 */
1843struct cache_args {
1844 struct dm_target *ti;
1845
1846 struct dm_dev *metadata_dev;
1847
1848 struct dm_dev *cache_dev;
1849 sector_t cache_sectors;
1850
1851 struct dm_dev *origin_dev;
1852 sector_t origin_sectors;
1853
1854 uint32_t block_size;
1855
1856 const char *policy_name;
1857 int policy_argc;
1858 const char **policy_argv;
1859
1860 struct cache_features features;
1861};
1862
1863static void destroy_cache_args(struct cache_args *ca)
1864{
1865 if (ca->metadata_dev)
1866 dm_put_device(ca->ti, ca->metadata_dev);
1867
1868 if (ca->cache_dev)
1869 dm_put_device(ca->ti, ca->cache_dev);
1870
1871 if (ca->origin_dev)
1872 dm_put_device(ca->ti, ca->origin_dev);
1873
1874 kfree(ca);
1875}
1876
1877static bool at_least_one_arg(struct dm_arg_set *as, char **error)
1878{
1879 if (!as->argc) {
1880 *error = "Insufficient args";
1881 return false;
1882 }
1883
1884 return true;
1885}
1886
1887static int parse_metadata_dev(struct cache_args *ca, struct dm_arg_set *as,
1888 char **error)
1889{
1890 int r;
1891 sector_t metadata_dev_size;
1892 char b[BDEVNAME_SIZE];
1893
1894 if (!at_least_one_arg(as, error))
1895 return -EINVAL;
1896
1897 r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
1898 &ca->metadata_dev);
1899 if (r) {
1900 *error = "Error opening metadata device";
1901 return r;
1902 }
1903
1904 metadata_dev_size = get_dev_size(ca->metadata_dev);
1905 if (metadata_dev_size > DM_CACHE_METADATA_MAX_SECTORS_WARNING)
1906 DMWARN("Metadata device %s is larger than %u sectors: excess space will not be used.",
1907 bdevname(ca->metadata_dev->bdev, b), THIN_METADATA_MAX_SECTORS);
1908
1909 return 0;
1910}
1911
1912static int parse_cache_dev(struct cache_args *ca, struct dm_arg_set *as,
1913 char **error)
1914{
1915 int r;
1916
1917 if (!at_least_one_arg(as, error))
1918 return -EINVAL;
1919
1920 r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
1921 &ca->cache_dev);
1922 if (r) {
1923 *error = "Error opening cache device";
1924 return r;
1925 }
1926 ca->cache_sectors = get_dev_size(ca->cache_dev);
1927
1928 return 0;
1929}
1930
1931static int parse_origin_dev(struct cache_args *ca, struct dm_arg_set *as,
1932 char **error)
1933{
1934 int r;
1935
1936 if (!at_least_one_arg(as, error))
1937 return -EINVAL;
1938
1939 r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
1940 &ca->origin_dev);
1941 if (r) {
1942 *error = "Error opening origin device";
1943 return r;
1944 }
1945
1946 ca->origin_sectors = get_dev_size(ca->origin_dev);
1947 if (ca->ti->len > ca->origin_sectors) {
1948 *error = "Device size larger than cached device";
1949 return -EINVAL;
1950 }
1951
1952 return 0;
1953}
1954
1955static int parse_block_size(struct cache_args *ca, struct dm_arg_set *as,
1956 char **error)
1957{
1958 unsigned long block_size;
1959
1960 if (!at_least_one_arg(as, error))
1961 return -EINVAL;
1962
1963 if (kstrtoul(dm_shift_arg(as), 10, &block_size) || !block_size ||
1964 block_size < DATA_DEV_BLOCK_SIZE_MIN_SECTORS ||
1965 block_size > DATA_DEV_BLOCK_SIZE_MAX_SECTORS ||
1966 block_size & (DATA_DEV_BLOCK_SIZE_MIN_SECTORS - 1)) {
1967 *error = "Invalid data block size";
1968 return -EINVAL;
1969 }
1970
1971 if (block_size > ca->cache_sectors) {
1972 *error = "Data block size is larger than the cache device";
1973 return -EINVAL;
1974 }
1975
1976 ca->block_size = block_size;
1977
1978 return 0;
1979}
1980
1981static void init_features(struct cache_features *cf)
1982{
1983 cf->mode = CM_WRITE;
1984 cf->io_mode = CM_IO_WRITEBACK;
1985}
1986
1987static int parse_features(struct cache_args *ca, struct dm_arg_set *as,
1988 char **error)
1989{
1990 static struct dm_arg _args[] = {
1991 {0, 1, "Invalid number of cache feature arguments"},
1992 };
1993
1994 int r;
1995 unsigned argc;
1996 const char *arg;
1997 struct cache_features *cf = &ca->features;
1998
1999 init_features(cf);
2000
2001 r = dm_read_arg_group(_args, as, &argc, error);
2002 if (r)
2003 return -EINVAL;
2004
2005 while (argc--) {
2006 arg = dm_shift_arg(as);
2007
2008 if (!strcasecmp(arg, "writeback"))
2009 cf->io_mode = CM_IO_WRITEBACK;
2010
2011 else if (!strcasecmp(arg, "writethrough"))
2012 cf->io_mode = CM_IO_WRITETHROUGH;
2013
2014 else if (!strcasecmp(arg, "passthrough"))
2015 cf->io_mode = CM_IO_PASSTHROUGH;
2016
2017 else {
2018 *error = "Unrecognised cache feature requested";
2019 return -EINVAL;
2020 }
2021 }
2022
2023 return 0;
2024}
2025
2026static int parse_policy(struct cache_args *ca, struct dm_arg_set *as,
2027 char **error)
2028{
2029 static struct dm_arg _args[] = {
2030 {0, 1024, "Invalid number of policy arguments"},
2031 };
2032
2033 int r;
2034
2035 if (!at_least_one_arg(as, error))
2036 return -EINVAL;
2037
2038 ca->policy_name = dm_shift_arg(as);
2039
2040 r = dm_read_arg_group(_args, as, &ca->policy_argc, error);
2041 if (r)
2042 return -EINVAL;
2043
2044 ca->policy_argv = (const char **)as->argv;
2045 dm_consume_args(as, ca->policy_argc);
2046
2047 return 0;
2048}
2049
2050static int parse_cache_args(struct cache_args *ca, int argc, char **argv,
2051 char **error)
2052{
2053 int r;
2054 struct dm_arg_set as;
2055
2056 as.argc = argc;
2057 as.argv = argv;
2058
2059 r = parse_metadata_dev(ca, &as, error);
2060 if (r)
2061 return r;
2062
2063 r = parse_cache_dev(ca, &as, error);
2064 if (r)
2065 return r;
2066
2067 r = parse_origin_dev(ca, &as, error);
2068 if (r)
2069 return r;
2070
2071 r = parse_block_size(ca, &as, error);
2072 if (r)
2073 return r;
2074
2075 r = parse_features(ca, &as, error);
2076 if (r)
2077 return r;
2078
2079 r = parse_policy(ca, &as, error);
2080 if (r)
2081 return r;
2082
2083 return 0;
2084}
2085
2086/*----------------------------------------------------------------*/
2087
2088static struct kmem_cache *migration_cache;
2089
2090#define NOT_CORE_OPTION 1
2091
2092static int process_config_option(struct cache *cache, const char *key, const char *value)
2093{
2094 unsigned long tmp;
2095
2096 if (!strcasecmp(key, "migration_threshold")) {
2097 if (kstrtoul(value, 10, &tmp))
2098 return -EINVAL;
2099
2100 cache->migration_threshold = tmp;
2101 return 0;
2102 }
2103
2104 return NOT_CORE_OPTION;
2105}
2106
2107static int set_config_value(struct cache *cache, const char *key, const char *value)
2108{
2109 int r = process_config_option(cache, key, value);
2110
2111 if (r == NOT_CORE_OPTION)
2112 r = policy_set_config_value(cache->policy, key, value);
2113
2114 if (r)
2115 DMWARN("bad config value for %s: %s", key, value);
2116
2117 return r;
2118}
2119
2120static int set_config_values(struct cache *cache, int argc, const char **argv)
2121{
2122 int r = 0;
2123
2124 if (argc & 1) {
2125 DMWARN("Odd number of policy arguments given but they should be <key> <value> pairs.");
2126 return -EINVAL;
2127 }
2128
2129 while (argc) {
2130 r = set_config_value(cache, argv[0], argv[1]);
2131 if (r)
2132 break;
2133
2134 argc -= 2;
2135 argv += 2;
2136 }
2137
2138 return r;
2139}
2140
2141static int create_cache_policy(struct cache *cache, struct cache_args *ca,
2142 char **error)
2143{
2144 struct dm_cache_policy *p = dm_cache_policy_create(ca->policy_name,
2145 cache->cache_size,
2146 cache->origin_sectors,
2147 cache->sectors_per_block);
2148 if (IS_ERR(p)) {
2149 *error = "Error creating cache's policy";
2150 return PTR_ERR(p);
2151 }
2152 cache->policy = p;
2153
2154 return 0;
2155}
2156
2157#define DEFAULT_MIGRATION_THRESHOLD 2048
2158
2159static int cache_create(struct cache_args *ca, struct cache **result)
2160{
2161 int r = 0;
2162 char **error = &ca->ti->error;
2163 struct cache *cache;
2164 struct dm_target *ti = ca->ti;
2165 dm_block_t origin_blocks;
2166 struct dm_cache_metadata *cmd;
2167 bool may_format = ca->features.mode == CM_WRITE;
2168
2169 cache = kzalloc(sizeof(*cache), GFP_KERNEL);
2170 if (!cache)
2171 return -ENOMEM;
2172
2173 cache->ti = ca->ti;
2174 ti->private = cache;
2175 ti->num_flush_bios = 2;
2176 ti->flush_supported = true;
2177
2178 ti->num_discard_bios = 1;
2179 ti->discards_supported = true;
2180 ti->discard_zeroes_data_unsupported = true;
2181 /* Discard bios must be split on a block boundary */
2182 ti->split_discard_bios = true;
2183
2184 cache->features = ca->features;
2185 ti->per_bio_data_size = get_per_bio_data_size(cache);
2186
2187 cache->callbacks.congested_fn = cache_is_congested;
2188 dm_table_add_target_callbacks(ti->table, &cache->callbacks);
2189
2190 cache->metadata_dev = ca->metadata_dev;
2191 cache->origin_dev = ca->origin_dev;
2192 cache->cache_dev = ca->cache_dev;
2193
2194 ca->metadata_dev = ca->origin_dev = ca->cache_dev = NULL;
2195
2196 /* FIXME: factor out this whole section */
2197 origin_blocks = cache->origin_sectors = ca->origin_sectors;
2198 origin_blocks = block_div(origin_blocks, ca->block_size);
2199 cache->origin_blocks = to_oblock(origin_blocks);
2200
2201 cache->sectors_per_block = ca->block_size;
2202 if (dm_set_target_max_io_len(ti, cache->sectors_per_block)) {
2203 r = -EINVAL;
2204 goto bad;
2205 }
2206
2207 if (ca->block_size & (ca->block_size - 1)) {
2208 dm_block_t cache_size = ca->cache_sectors;
2209
2210 cache->sectors_per_block_shift = -1;
2211 cache_size = block_div(cache_size, ca->block_size);
2212 cache->cache_size = to_cblock(cache_size);
2213 } else {
2214 cache->sectors_per_block_shift = __ffs(ca->block_size);
2215 cache->cache_size = to_cblock(ca->cache_sectors >> cache->sectors_per_block_shift);
2216 }
2217
2218 r = create_cache_policy(cache, ca, error);
2219 if (r)
2220 goto bad;
2221
2222 cache->policy_nr_args = ca->policy_argc;
2223 cache->migration_threshold = DEFAULT_MIGRATION_THRESHOLD;
2224
2225 r = set_config_values(cache, ca->policy_argc, ca->policy_argv);
2226 if (r) {
2227 *error = "Error setting cache policy's config values";
2228 goto bad;
2229 }
2230
2231 cmd = dm_cache_metadata_open(cache->metadata_dev->bdev,
2232 ca->block_size, may_format,
2233 dm_cache_policy_get_hint_size(cache->policy));
2234 if (IS_ERR(cmd)) {
2235 *error = "Error creating metadata object";
2236 r = PTR_ERR(cmd);
2237 goto bad;
2238 }
2239 cache->cmd = cmd;
2240
2241 if (passthrough_mode(&cache->features)) {
2242 bool all_clean;
2243
2244 r = dm_cache_metadata_all_clean(cache->cmd, &all_clean);
2245 if (r) {
2246 *error = "dm_cache_metadata_all_clean() failed";
2247 goto bad;
2248 }
2249
2250 if (!all_clean) {
2251 *error = "Cannot enter passthrough mode unless all blocks are clean";
2252 r = -EINVAL;
2253 goto bad;
2254 }
2255 }
2256
2257 spin_lock_init(&cache->lock);
2258 bio_list_init(&cache->deferred_bios);
2259 bio_list_init(&cache->deferred_flush_bios);
2260 bio_list_init(&cache->deferred_writethrough_bios);
2261 INIT_LIST_HEAD(&cache->quiesced_migrations);
2262 INIT_LIST_HEAD(&cache->completed_migrations);
2263 INIT_LIST_HEAD(&cache->need_commit_migrations);
2264 atomic_set(&cache->nr_migrations, 0);
2265 init_waitqueue_head(&cache->migration_wait);
2266
2267 init_waitqueue_head(&cache->quiescing_wait);
2268 atomic_set(&cache->quiescing, 0);
2269 atomic_set(&cache->quiescing_ack, 0);
2270
2271 r = -ENOMEM;
2272 cache->nr_dirty = 0;
2273 cache->dirty_bitset = alloc_bitset(from_cblock(cache->cache_size));
2274 if (!cache->dirty_bitset) {
2275 *error = "could not allocate dirty bitset";
2276 goto bad;
2277 }
2278 clear_bitset(cache->dirty_bitset, from_cblock(cache->cache_size));
2279
2280 cache->discard_nr_blocks = cache->origin_blocks;
2281 cache->discard_bitset = alloc_bitset(from_oblock(cache->discard_nr_blocks));
2282 if (!cache->discard_bitset) {
2283 *error = "could not allocate discard bitset";
2284 goto bad;
2285 }
2286 clear_bitset(cache->discard_bitset, from_oblock(cache->discard_nr_blocks));
2287
2288 cache->copier = dm_kcopyd_client_create(&dm_kcopyd_throttle);
2289 if (IS_ERR(cache->copier)) {
2290 *error = "could not create kcopyd client";
2291 r = PTR_ERR(cache->copier);
2292 goto bad;
2293 }
2294
2295 cache->wq = alloc_ordered_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM);
2296 if (!cache->wq) {
2297 *error = "could not create workqueue for metadata object";
2298 goto bad;
2299 }
2300 INIT_WORK(&cache->worker, do_worker);
2301 INIT_DELAYED_WORK(&cache->waker, do_waker);
2302 cache->last_commit_jiffies = jiffies;
2303
2304 cache->prison = dm_bio_prison_create(PRISON_CELLS);
2305 if (!cache->prison) {
2306 *error = "could not create bio prison";
2307 goto bad;
2308 }
2309
2310 cache->all_io_ds = dm_deferred_set_create();
2311 if (!cache->all_io_ds) {
2312 *error = "could not create all_io deferred set";
2313 goto bad;
2314 }
2315
2316 cache->migration_pool = mempool_create_slab_pool(MIGRATION_POOL_SIZE,
2317 migration_cache);
2318 if (!cache->migration_pool) {
2319 *error = "Error creating cache's migration mempool";
2320 goto bad;
2321 }
2322
2323 cache->next_migration = NULL;
2324
2325 cache->need_tick_bio = true;
2326 cache->sized = false;
2327 cache->invalidate = false;
2328 cache->commit_requested = false;
2329 cache->loaded_mappings = false;
2330 cache->loaded_discards = false;
2331
2332 load_stats(cache);
2333
2334 atomic_set(&cache->stats.demotion, 0);
2335 atomic_set(&cache->stats.promotion, 0);
2336 atomic_set(&cache->stats.copies_avoided, 0);
2337 atomic_set(&cache->stats.cache_cell_clash, 0);
2338 atomic_set(&cache->stats.commit_count, 0);
2339 atomic_set(&cache->stats.discard_count, 0);
2340
2341 spin_lock_init(&cache->invalidation_lock);
2342 INIT_LIST_HEAD(&cache->invalidation_requests);
2343
2344 *result = cache;
2345 return 0;
2346
2347bad:
2348 destroy(cache);
2349 return r;
2350}
2351
2352static int copy_ctr_args(struct cache *cache, int argc, const char **argv)
2353{
2354 unsigned i;
2355 const char **copy;
2356
2357 copy = kcalloc(argc, sizeof(*copy), GFP_KERNEL);
2358 if (!copy)
2359 return -ENOMEM;
2360 for (i = 0; i < argc; i++) {
2361 copy[i] = kstrdup(argv[i], GFP_KERNEL);
2362 if (!copy[i]) {
2363 while (i--)
2364 kfree(copy[i]);
2365 kfree(copy);
2366 return -ENOMEM;
2367 }
2368 }
2369
2370 cache->nr_ctr_args = argc;
2371 cache->ctr_args = copy;
2372
2373 return 0;
2374}
2375
2376static int cache_ctr(struct dm_target *ti, unsigned argc, char **argv)
2377{
2378 int r = -EINVAL;
2379 struct cache_args *ca;
2380 struct cache *cache = NULL;
2381
2382 ca = kzalloc(sizeof(*ca), GFP_KERNEL);
2383 if (!ca) {
2384 ti->error = "Error allocating memory for cache";
2385 return -ENOMEM;
2386 }
2387 ca->ti = ti;
2388
2389 r = parse_cache_args(ca, argc, argv, &ti->error);
2390 if (r)
2391 goto out;
2392
2393 r = cache_create(ca, &cache);
2394 if (r)
2395 goto out;
2396
2397 r = copy_ctr_args(cache, argc - 3, (const char **)argv + 3);
2398 if (r) {
2399 destroy(cache);
2400 goto out;
2401 }
2402
2403 ti->private = cache;
2404
2405out:
2406 destroy_cache_args(ca);
2407 return r;
2408}
2409
2410static int cache_map(struct dm_target *ti, struct bio *bio)
2411{
2412 struct cache *cache = ti->private;
2413
2414 int r;
2415 dm_oblock_t block = get_bio_block(cache, bio);
2416 size_t pb_data_size = get_per_bio_data_size(cache);
2417 bool can_migrate = false;
2418 bool discarded_block;
2419 struct dm_bio_prison_cell *cell;
2420 struct policy_result lookup_result;
2421 struct per_bio_data *pb = init_per_bio_data(bio, pb_data_size);
2422
2423 if (unlikely(from_oblock(block) >= from_oblock(cache->origin_blocks))) {
2424 /*
2425 * This can only occur if the io goes to a partial block at
2426 * the end of the origin device. We don't cache these.
2427 * Just remap to the origin and carry on.
2428 */
2429 remap_to_origin(cache, bio);
2430 return DM_MAPIO_REMAPPED;
2431 }
2432
2433 if (bio->bi_rw & (REQ_FLUSH | REQ_FUA | REQ_DISCARD)) {
2434 defer_bio(cache, bio);
2435 return DM_MAPIO_SUBMITTED;
2436 }
2437
2438 /*
2439 * Check to see if that block is currently migrating.
2440 */
2441 cell = alloc_prison_cell(cache);
2442 if (!cell) {
2443 defer_bio(cache, bio);
2444 return DM_MAPIO_SUBMITTED;
2445 }
2446
2447 r = bio_detain(cache, block, bio, cell,
2448 (cell_free_fn) free_prison_cell,
2449 cache, &cell);
2450 if (r) {
2451 if (r < 0)
2452 defer_bio(cache, bio);
2453
2454 return DM_MAPIO_SUBMITTED;
2455 }
2456
2457 discarded_block = is_discarded_oblock(cache, block);
2458
2459 r = policy_map(cache->policy, block, false, can_migrate, discarded_block,
2460 bio, &lookup_result);
2461 if (r == -EWOULDBLOCK) {
2462 cell_defer(cache, cell, true);
2463 return DM_MAPIO_SUBMITTED;
2464
2465 } else if (r) {
2466 DMERR_LIMIT("Unexpected return from cache replacement policy: %d", r);
2467 bio_io_error(bio);
2468 return DM_MAPIO_SUBMITTED;
2469 }
2470
2471 r = DM_MAPIO_REMAPPED;
2472 switch (lookup_result.op) {
2473 case POLICY_HIT:
2474 if (passthrough_mode(&cache->features)) {
2475 if (bio_data_dir(bio) == WRITE) {
2476 /*
2477 * We need to invalidate this block, so
2478 * defer for the worker thread.
2479 */
2480 cell_defer(cache, cell, true);
2481 r = DM_MAPIO_SUBMITTED;
2482
2483 } else {
2484 pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
2485 inc_miss_counter(cache, bio);
2486 remap_to_origin_clear_discard(cache, bio, block);
2487
2488 cell_defer(cache, cell, false);
2489 }
2490
2491 } else {
2492 inc_hit_counter(cache, bio);
2493 pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
2494
2495 if (bio_data_dir(bio) == WRITE && writethrough_mode(&cache->features) &&
2496 !is_dirty(cache, lookup_result.cblock))
2497 remap_to_origin_then_cache(cache, bio, block, lookup_result.cblock);
2498 else
2499 remap_to_cache_dirty(cache, bio, block, lookup_result.cblock);
2500
2501 cell_defer(cache, cell, false);
2502 }
2503 break;
2504
2505 case POLICY_MISS:
2506 inc_miss_counter(cache, bio);
2507 pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
2508
2509 if (pb->req_nr != 0) {
2510 /*
2511 * This is a duplicate writethrough io that is no
2512 * longer needed because the block has been demoted.
2513 */
2514 bio_endio(bio, 0);
2515 cell_defer(cache, cell, false);
2516 return DM_MAPIO_SUBMITTED;
2517 } else {
2518 remap_to_origin_clear_discard(cache, bio, block);
2519 cell_defer(cache, cell, false);
2520 }
2521 break;
2522
2523 default:
2524 DMERR_LIMIT("%s: erroring bio: unknown policy op: %u", __func__,
2525 (unsigned) lookup_result.op);
2526 bio_io_error(bio);
2527 r = DM_MAPIO_SUBMITTED;
2528 }
2529
2530 return r;
2531}
2532
2533static int cache_end_io(struct dm_target *ti, struct bio *bio, int error)
2534{
2535 struct cache *cache = ti->private;
2536 unsigned long flags;
2537 size_t pb_data_size = get_per_bio_data_size(cache);
2538 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
2539
2540 if (pb->tick) {
2541 policy_tick(cache->policy);
2542
2543 spin_lock_irqsave(&cache->lock, flags);
2544 cache->need_tick_bio = true;
2545 spin_unlock_irqrestore(&cache->lock, flags);
2546 }
2547
2548 check_for_quiesced_migrations(cache, pb);
2549
2550 return 0;
2551}
2552
2553static int write_dirty_bitset(struct cache *cache)
2554{
2555 unsigned i, r;
2556
2557 for (i = 0; i < from_cblock(cache->cache_size); i++) {
2558 r = dm_cache_set_dirty(cache->cmd, to_cblock(i),
2559 is_dirty(cache, to_cblock(i)));
2560 if (r)
2561 return r;
2562 }
2563
2564 return 0;
2565}
2566
2567static int write_discard_bitset(struct cache *cache)
2568{
2569 unsigned i, r;
2570
2571 r = dm_cache_discard_bitset_resize(cache->cmd, cache->sectors_per_block,
2572 cache->origin_blocks);
2573 if (r) {
2574 DMERR("could not resize on-disk discard bitset");
2575 return r;
2576 }
2577
2578 for (i = 0; i < from_oblock(cache->discard_nr_blocks); i++) {
2579 r = dm_cache_set_discard(cache->cmd, to_oblock(i),
2580 is_discarded(cache, to_oblock(i)));
2581 if (r)
2582 return r;
2583 }
2584
2585 return 0;
2586}
2587
2588/*
2589 * returns true on success
2590 */
2591static bool sync_metadata(struct cache *cache)
2592{
2593 int r1, r2, r3, r4;
2594
2595 r1 = write_dirty_bitset(cache);
2596 if (r1)
2597 DMERR("could not write dirty bitset");
2598
2599 r2 = write_discard_bitset(cache);
2600 if (r2)
2601 DMERR("could not write discard bitset");
2602
2603 save_stats(cache);
2604
2605 r3 = dm_cache_write_hints(cache->cmd, cache->policy);
2606 if (r3)
2607 DMERR("could not write hints");
2608
2609 /*
2610 * If writing the above metadata failed, we still commit, but don't
2611 * set the clean shutdown flag. This will effectively force every
2612 * dirty bit to be set on reload.
2613 */
2614 r4 = dm_cache_commit(cache->cmd, !r1 && !r2 && !r3);
2615 if (r4)
2616 DMERR("could not write cache metadata. Data loss may occur.");
2617
2618 return !r1 && !r2 && !r3 && !r4;
2619}
2620
2621static void cache_postsuspend(struct dm_target *ti)
2622{
2623 struct cache *cache = ti->private;
2624
2625 start_quiescing(cache);
2626 wait_for_migrations(cache);
2627 stop_worker(cache);
2628 requeue_deferred_io(cache);
2629 stop_quiescing(cache);
2630
2631 (void) sync_metadata(cache);
2632}
2633
2634static int load_mapping(void *context, dm_oblock_t oblock, dm_cblock_t cblock,
2635 bool dirty, uint32_t hint, bool hint_valid)
2636{
2637 int r;
2638 struct cache *cache = context;
2639
2640 r = policy_load_mapping(cache->policy, oblock, cblock, hint, hint_valid);
2641 if (r)
2642 return r;
2643
2644 if (dirty)
2645 set_dirty(cache, oblock, cblock);
2646 else
2647 clear_dirty(cache, oblock, cblock);
2648
2649 return 0;
2650}
2651
2652static int load_discard(void *context, sector_t discard_block_size,
2653 dm_oblock_t oblock, bool discard)
2654{
2655 struct cache *cache = context;
2656
2657 if (discard)
2658 set_discard(cache, oblock);
2659 else
2660 clear_discard(cache, oblock);
2661
2662 return 0;
2663}
2664
2665static dm_cblock_t get_cache_dev_size(struct cache *cache)
2666{
2667 sector_t size = get_dev_size(cache->cache_dev);
2668 (void) sector_div(size, cache->sectors_per_block);
2669 return to_cblock(size);
2670}
2671
2672static bool can_resize(struct cache *cache, dm_cblock_t new_size)
2673{
2674 if (from_cblock(new_size) > from_cblock(cache->cache_size))
2675 return true;
2676
2677 /*
2678 * We can't drop a dirty block when shrinking the cache.
2679 */
2680 while (from_cblock(new_size) < from_cblock(cache->cache_size)) {
2681 new_size = to_cblock(from_cblock(new_size) + 1);
2682 if (is_dirty(cache, new_size)) {
2683 DMERR("unable to shrink cache; cache block %llu is dirty",
2684 (unsigned long long) from_cblock(new_size));
2685 return false;
2686 }
2687 }
2688
2689 return true;
2690}
2691
2692static int resize_cache_dev(struct cache *cache, dm_cblock_t new_size)
2693{
2694 int r;
2695
2696 r = dm_cache_resize(cache->cmd, new_size);
2697 if (r) {
2698 DMERR("could not resize cache metadata");
2699 return r;
2700 }
2701
2702 cache->cache_size = new_size;
2703
2704 return 0;
2705}
2706
2707static int cache_preresume(struct dm_target *ti)
2708{
2709 int r = 0;
2710 struct cache *cache = ti->private;
2711 dm_cblock_t csize = get_cache_dev_size(cache);
2712
2713 /*
2714 * Check to see if the cache has resized.
2715 */
2716 if (!cache->sized) {
2717 r = resize_cache_dev(cache, csize);
2718 if (r)
2719 return r;
2720
2721 cache->sized = true;
2722
2723 } else if (csize != cache->cache_size) {
2724 if (!can_resize(cache, csize))
2725 return -EINVAL;
2726
2727 r = resize_cache_dev(cache, csize);
2728 if (r)
2729 return r;
2730 }
2731
2732 if (!cache->loaded_mappings) {
2733 r = dm_cache_load_mappings(cache->cmd, cache->policy,
2734 load_mapping, cache);
2735 if (r) {
2736 DMERR("could not load cache mappings");
2737 return r;
2738 }
2739
2740 cache->loaded_mappings = true;
2741 }
2742
2743 if (!cache->loaded_discards) {
2744 r = dm_cache_load_discards(cache->cmd, load_discard, cache);
2745 if (r) {
2746 DMERR("could not load origin discards");
2747 return r;
2748 }
2749
2750 cache->loaded_discards = true;
2751 }
2752
2753 return r;
2754}
2755
2756static void cache_resume(struct dm_target *ti)
2757{
2758 struct cache *cache = ti->private;
2759
2760 cache->need_tick_bio = true;
2761 do_waker(&cache->waker.work);
2762}
2763
2764/*
2765 * Status format:
2766 *
2767 * <metadata block size> <#used metadata blocks>/<#total metadata blocks>
2768 * <cache block size> <#used cache blocks>/<#total cache blocks>
2769 * <#read hits> <#read misses> <#write hits> <#write misses>
2770 * <#demotions> <#promotions> <#dirty>
2771 * <#features> <features>*
2772 * <#core args> <core args>
2773 * <policy name> <#policy args> <policy args>*
2774 */
2775static void cache_status(struct dm_target *ti, status_type_t type,
2776 unsigned status_flags, char *result, unsigned maxlen)
2777{
2778 int r = 0;
2779 unsigned i;
2780 ssize_t sz = 0;
2781 dm_block_t nr_free_blocks_metadata = 0;
2782 dm_block_t nr_blocks_metadata = 0;
2783 char buf[BDEVNAME_SIZE];
2784 struct cache *cache = ti->private;
2785 dm_cblock_t residency;
2786
2787 switch (type) {
2788 case STATUSTYPE_INFO:
2789 /* Commit to ensure statistics aren't out-of-date */
2790 if (!(status_flags & DM_STATUS_NOFLUSH_FLAG) && !dm_suspended(ti)) {
2791 r = dm_cache_commit(cache->cmd, false);
2792 if (r)
2793 DMERR("could not commit metadata for accurate status");
2794 }
2795
2796 r = dm_cache_get_free_metadata_block_count(cache->cmd,
2797 &nr_free_blocks_metadata);
2798 if (r) {
2799 DMERR("could not get metadata free block count");
2800 goto err;
2801 }
2802
2803 r = dm_cache_get_metadata_dev_size(cache->cmd, &nr_blocks_metadata);
2804 if (r) {
2805 DMERR("could not get metadata device size");
2806 goto err;
2807 }
2808
2809 residency = policy_residency(cache->policy);
2810
2811 DMEMIT("%u %llu/%llu %u %llu/%llu %u %u %u %u %u %u %llu ",
2812 (unsigned)(DM_CACHE_METADATA_BLOCK_SIZE >> SECTOR_SHIFT),
2813 (unsigned long long)(nr_blocks_metadata - nr_free_blocks_metadata),
2814 (unsigned long long)nr_blocks_metadata,
2815 cache->sectors_per_block,
2816 (unsigned long long) from_cblock(residency),
2817 (unsigned long long) from_cblock(cache->cache_size),
2818 (unsigned) atomic_read(&cache->stats.read_hit),
2819 (unsigned) atomic_read(&cache->stats.read_miss),
2820 (unsigned) atomic_read(&cache->stats.write_hit),
2821 (unsigned) atomic_read(&cache->stats.write_miss),
2822 (unsigned) atomic_read(&cache->stats.demotion),
2823 (unsigned) atomic_read(&cache->stats.promotion),
2824 (unsigned long long) from_cblock(cache->nr_dirty));
2825
2826 if (writethrough_mode(&cache->features))
2827 DMEMIT("1 writethrough ");
2828
2829 else if (passthrough_mode(&cache->features))
2830 DMEMIT("1 passthrough ");
2831
2832 else if (writeback_mode(&cache->features))
2833 DMEMIT("1 writeback ");
2834
2835 else {
2836 DMERR("internal error: unknown io mode: %d", (int) cache->features.io_mode);
2837 goto err;
2838 }
2839
2840 DMEMIT("2 migration_threshold %llu ", (unsigned long long) cache->migration_threshold);
2841
2842 DMEMIT("%s ", dm_cache_policy_get_name(cache->policy));
2843 if (sz < maxlen) {
2844 r = policy_emit_config_values(cache->policy, result + sz, maxlen - sz);
2845 if (r)
2846 DMERR("policy_emit_config_values returned %d", r);
2847 }
2848
2849 break;
2850
2851 case STATUSTYPE_TABLE:
2852 format_dev_t(buf, cache->metadata_dev->bdev->bd_dev);
2853 DMEMIT("%s ", buf);
2854 format_dev_t(buf, cache->cache_dev->bdev->bd_dev);
2855 DMEMIT("%s ", buf);
2856 format_dev_t(buf, cache->origin_dev->bdev->bd_dev);
2857 DMEMIT("%s", buf);
2858
2859 for (i = 0; i < cache->nr_ctr_args - 1; i++)
2860 DMEMIT(" %s", cache->ctr_args[i]);
2861 if (cache->nr_ctr_args)
2862 DMEMIT(" %s", cache->ctr_args[cache->nr_ctr_args - 1]);
2863 }
2864
2865 return;
2866
2867err:
2868 DMEMIT("Error");
2869}
2870
2871/*
2872 * A cache block range can take two forms:
2873 *
2874 * i) A single cblock, eg. '3456'
2875 * ii) A begin and end cblock with dots between, eg. 123-234
2876 */
2877static int parse_cblock_range(struct cache *cache, const char *str,
2878 struct cblock_range *result)
2879{
2880 char dummy;
2881 uint64_t b, e;
2882 int r;
2883
2884 /*
2885 * Try and parse form (ii) first.
2886 */
2887 r = sscanf(str, "%llu-%llu%c", &b, &e, &dummy);
2888 if (r < 0)
2889 return r;
2890
2891 if (r == 2) {
2892 result->begin = to_cblock(b);
2893 result->end = to_cblock(e);
2894 return 0;
2895 }
2896
2897 /*
2898 * That didn't work, try form (i).
2899 */
2900 r = sscanf(str, "%llu%c", &b, &dummy);
2901 if (r < 0)
2902 return r;
2903
2904 if (r == 1) {
2905 result->begin = to_cblock(b);
2906 result->end = to_cblock(from_cblock(result->begin) + 1u);
2907 return 0;
2908 }
2909
2910 DMERR("invalid cblock range '%s'", str);
2911 return -EINVAL;
2912}
2913
2914static int validate_cblock_range(struct cache *cache, struct cblock_range *range)
2915{
2916 uint64_t b = from_cblock(range->begin);
2917 uint64_t e = from_cblock(range->end);
2918 uint64_t n = from_cblock(cache->cache_size);
2919
2920 if (b >= n) {
2921 DMERR("begin cblock out of range: %llu >= %llu", b, n);
2922 return -EINVAL;
2923 }
2924
2925 if (e > n) {
2926 DMERR("end cblock out of range: %llu > %llu", e, n);
2927 return -EINVAL;
2928 }
2929
2930 if (b >= e) {
2931 DMERR("invalid cblock range: %llu >= %llu", b, e);
2932 return -EINVAL;
2933 }
2934
2935 return 0;
2936}
2937
2938static int request_invalidation(struct cache *cache, struct cblock_range *range)
2939{
2940 struct invalidation_request req;
2941
2942 INIT_LIST_HEAD(&req.list);
2943 req.cblocks = range;
2944 atomic_set(&req.complete, 0);
2945 req.err = 0;
2946 init_waitqueue_head(&req.result_wait);
2947
2948 spin_lock(&cache->invalidation_lock);
2949 list_add(&req.list, &cache->invalidation_requests);
2950 spin_unlock(&cache->invalidation_lock);
2951 wake_worker(cache);
2952
2953 wait_event(req.result_wait, atomic_read(&req.complete));
2954 return req.err;
2955}
2956
2957static int process_invalidate_cblocks_message(struct cache *cache, unsigned count,
2958 const char **cblock_ranges)
2959{
2960 int r = 0;
2961 unsigned i;
2962 struct cblock_range range;
2963
2964 if (!passthrough_mode(&cache->features)) {
2965 DMERR("cache has to be in passthrough mode for invalidation");
2966 return -EPERM;
2967 }
2968
2969 for (i = 0; i < count; i++) {
2970 r = parse_cblock_range(cache, cblock_ranges[i], &range);
2971 if (r)
2972 break;
2973
2974 r = validate_cblock_range(cache, &range);
2975 if (r)
2976 break;
2977
2978 /*
2979 * Pass begin and end origin blocks to the worker and wake it.
2980 */
2981 r = request_invalidation(cache, &range);
2982 if (r)
2983 break;
2984 }
2985
2986 return r;
2987}
2988
2989/*
2990 * Supports
2991 * "<key> <value>"
2992 * and
2993 * "invalidate_cblocks [(<begin>)|(<begin>-<end>)]*
2994 *
2995 * The key migration_threshold is supported by the cache target core.
2996 */
2997static int cache_message(struct dm_target *ti, unsigned argc, char **argv)
2998{
2999 struct cache *cache = ti->private;
3000
3001 if (!argc)
3002 return -EINVAL;
3003
3004 if (!strcasecmp(argv[0], "invalidate_cblocks"))
3005 return process_invalidate_cblocks_message(cache, argc - 1, (const char **) argv + 1);
3006
3007 if (argc != 2)
3008 return -EINVAL;
3009
3010 return set_config_value(cache, argv[0], argv[1]);
3011}
3012
3013static int cache_iterate_devices(struct dm_target *ti,
3014 iterate_devices_callout_fn fn, void *data)
3015{
3016 int r = 0;
3017 struct cache *cache = ti->private;
3018
3019 r = fn(ti, cache->cache_dev, 0, get_dev_size(cache->cache_dev), data);
3020 if (!r)
3021 r = fn(ti, cache->origin_dev, 0, ti->len, data);
3022
3023 return r;
3024}
3025
3026/*
3027 * We assume I/O is going to the origin (which is the volume
3028 * more likely to have restrictions e.g. by being striped).
3029 * (Looking up the exact location of the data would be expensive
3030 * and could always be out of date by the time the bio is submitted.)
3031 */
3032static int cache_bvec_merge(struct dm_target *ti,
3033 struct bvec_merge_data *bvm,
3034 struct bio_vec *biovec, int max_size)
3035{
3036 struct cache *cache = ti->private;
3037 struct request_queue *q = bdev_get_queue(cache->origin_dev->bdev);
3038
3039 if (!q->merge_bvec_fn)
3040 return max_size;
3041
3042 bvm->bi_bdev = cache->origin_dev->bdev;
3043 return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
3044}
3045
3046static void set_discard_limits(struct cache *cache, struct queue_limits *limits)
3047{
3048 /*
3049 * FIXME: these limits may be incompatible with the cache device
3050 */
3051 limits->max_discard_sectors = cache->sectors_per_block;
3052 limits->discard_granularity = cache->sectors_per_block << SECTOR_SHIFT;
3053}
3054
3055static void cache_io_hints(struct dm_target *ti, struct queue_limits *limits)
3056{
3057 struct cache *cache = ti->private;
3058 uint64_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;
3059
3060 /*
3061 * If the system-determined stacked limits are compatible with the
3062 * cache's blocksize (io_opt is a factor) do not override them.
3063 */
3064 if (io_opt_sectors < cache->sectors_per_block ||
3065 do_div(io_opt_sectors, cache->sectors_per_block)) {
3066 blk_limits_io_min(limits, 0);
3067 blk_limits_io_opt(limits, cache->sectors_per_block << SECTOR_SHIFT);
3068 }
3069 set_discard_limits(cache, limits);
3070}
3071
3072/*----------------------------------------------------------------*/
3073
3074static struct target_type cache_target = {
3075 .name = "cache",
3076 .version = {1, 4, 0},
3077 .module = THIS_MODULE,
3078 .ctr = cache_ctr,
3079 .dtr = cache_dtr,
3080 .map = cache_map,
3081 .end_io = cache_end_io,
3082 .postsuspend = cache_postsuspend,
3083 .preresume = cache_preresume,
3084 .resume = cache_resume,
3085 .status = cache_status,
3086 .message = cache_message,
3087 .iterate_devices = cache_iterate_devices,
3088 .merge = cache_bvec_merge,
3089 .io_hints = cache_io_hints,
3090};
3091
3092static int __init dm_cache_init(void)
3093{
3094 int r;
3095
3096 r = dm_register_target(&cache_target);
3097 if (r) {
3098 DMERR("cache target registration failed: %d", r);
3099 return r;
3100 }
3101
3102 migration_cache = KMEM_CACHE(dm_cache_migration, 0);
3103 if (!migration_cache) {
3104 dm_unregister_target(&cache_target);
3105 return -ENOMEM;
3106 }
3107
3108 return 0;
3109}
3110
3111static void __exit dm_cache_exit(void)
3112{
3113 dm_unregister_target(&cache_target);
3114 kmem_cache_destroy(migration_cache);
3115}
3116
3117module_init(dm_cache_init);
3118module_exit(dm_cache_exit);
3119
3120MODULE_DESCRIPTION(DM_NAME " cache target");
3121MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
3122MODULE_LICENSE("GPL");