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1/*
2 * Copyright (C) 2012 Red Hat. All rights reserved.
3 *
4 * This file is released under the GPL.
5 */
6
7#include "dm.h"
8#include "dm-bio-prison.h"
9#include "dm-bio-record.h"
10#include "dm-cache-metadata.h"
11
12#include <linux/dm-io.h>
13#include <linux/dm-kcopyd.h>
14#include <linux/jiffies.h>
15#include <linux/init.h>
16#include <linux/mempool.h>
17#include <linux/module.h>
18#include <linux/slab.h>
19#include <linux/vmalloc.h>
20
21#define DM_MSG_PREFIX "cache"
22
23DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(cache_copy_throttle,
24 "A percentage of time allocated for copying to and/or from cache");
25
26/*----------------------------------------------------------------*/
27
28#define IOT_RESOLUTION 4
29
30struct io_tracker {
31 spinlock_t lock;
32
33 /*
34 * Sectors of in-flight IO.
35 */
36 sector_t in_flight;
37
38 /*
39 * The time, in jiffies, when this device became idle (if it is
40 * indeed idle).
41 */
42 unsigned long idle_time;
43 unsigned long last_update_time;
44};
45
46static void iot_init(struct io_tracker *iot)
47{
48 spin_lock_init(&iot->lock);
49 iot->in_flight = 0ul;
50 iot->idle_time = 0ul;
51 iot->last_update_time = jiffies;
52}
53
54static bool __iot_idle_for(struct io_tracker *iot, unsigned long jifs)
55{
56 if (iot->in_flight)
57 return false;
58
59 return time_after(jiffies, iot->idle_time + jifs);
60}
61
62static bool iot_idle_for(struct io_tracker *iot, unsigned long jifs)
63{
64 bool r;
65 unsigned long flags;
66
67 spin_lock_irqsave(&iot->lock, flags);
68 r = __iot_idle_for(iot, jifs);
69 spin_unlock_irqrestore(&iot->lock, flags);
70
71 return r;
72}
73
74static void iot_io_begin(struct io_tracker *iot, sector_t len)
75{
76 unsigned long flags;
77
78 spin_lock_irqsave(&iot->lock, flags);
79 iot->in_flight += len;
80 spin_unlock_irqrestore(&iot->lock, flags);
81}
82
83static void __iot_io_end(struct io_tracker *iot, sector_t len)
84{
85 iot->in_flight -= len;
86 if (!iot->in_flight)
87 iot->idle_time = jiffies;
88}
89
90static void iot_io_end(struct io_tracker *iot, sector_t len)
91{
92 unsigned long flags;
93
94 spin_lock_irqsave(&iot->lock, flags);
95 __iot_io_end(iot, len);
96 spin_unlock_irqrestore(&iot->lock, flags);
97}
98
99/*----------------------------------------------------------------*/
100
101/*
102 * Glossary:
103 *
104 * oblock: index of an origin block
105 * cblock: index of a cache block
106 * promotion: movement of a block from origin to cache
107 * demotion: movement of a block from cache to origin
108 * migration: movement of a block between the origin and cache device,
109 * either direction
110 */
111
112/*----------------------------------------------------------------*/
113
114/*
115 * There are a couple of places where we let a bio run, but want to do some
116 * work before calling its endio function. We do this by temporarily
117 * changing the endio fn.
118 */
119struct dm_hook_info {
120 bio_end_io_t *bi_end_io;
121};
122
123static void dm_hook_bio(struct dm_hook_info *h, struct bio *bio,
124 bio_end_io_t *bi_end_io, void *bi_private)
125{
126 h->bi_end_io = bio->bi_end_io;
127
128 bio->bi_end_io = bi_end_io;
129 bio->bi_private = bi_private;
130}
131
132static void dm_unhook_bio(struct dm_hook_info *h, struct bio *bio)
133{
134 bio->bi_end_io = h->bi_end_io;
135}
136
137/*----------------------------------------------------------------*/
138
139#define MIGRATION_POOL_SIZE 128
140#define COMMIT_PERIOD HZ
141#define MIGRATION_COUNT_WINDOW 10
142
143/*
144 * The block size of the device holding cache data must be
145 * between 32KB and 1GB.
146 */
147#define DATA_DEV_BLOCK_SIZE_MIN_SECTORS (32 * 1024 >> SECTOR_SHIFT)
148#define DATA_DEV_BLOCK_SIZE_MAX_SECTORS (1024 * 1024 * 1024 >> SECTOR_SHIFT)
149
150enum cache_metadata_mode {
151 CM_WRITE, /* metadata may be changed */
152 CM_READ_ONLY, /* metadata may not be changed */
153 CM_FAIL
154};
155
156enum cache_io_mode {
157 /*
158 * Data is written to cached blocks only. These blocks are marked
159 * dirty. If you lose the cache device you will lose data.
160 * Potential performance increase for both reads and writes.
161 */
162 CM_IO_WRITEBACK,
163
164 /*
165 * Data is written to both cache and origin. Blocks are never
166 * dirty. Potential performance benfit for reads only.
167 */
168 CM_IO_WRITETHROUGH,
169
170 /*
171 * A degraded mode useful for various cache coherency situations
172 * (eg, rolling back snapshots). Reads and writes always go to the
173 * origin. If a write goes to a cached oblock, then the cache
174 * block is invalidated.
175 */
176 CM_IO_PASSTHROUGH
177};
178
179struct cache_features {
180 enum cache_metadata_mode mode;
181 enum cache_io_mode io_mode;
182};
183
184struct cache_stats {
185 atomic_t read_hit;
186 atomic_t read_miss;
187 atomic_t write_hit;
188 atomic_t write_miss;
189 atomic_t demotion;
190 atomic_t promotion;
191 atomic_t copies_avoided;
192 atomic_t cache_cell_clash;
193 atomic_t commit_count;
194 atomic_t discard_count;
195};
196
197/*
198 * Defines a range of cblocks, begin to (end - 1) are in the range. end is
199 * the one-past-the-end value.
200 */
201struct cblock_range {
202 dm_cblock_t begin;
203 dm_cblock_t end;
204};
205
206struct invalidation_request {
207 struct list_head list;
208 struct cblock_range *cblocks;
209
210 atomic_t complete;
211 int err;
212
213 wait_queue_head_t result_wait;
214};
215
216struct cache {
217 struct dm_target *ti;
218 struct dm_target_callbacks callbacks;
219
220 struct dm_cache_metadata *cmd;
221
222 /*
223 * Metadata is written to this device.
224 */
225 struct dm_dev *metadata_dev;
226
227 /*
228 * The slower of the two data devices. Typically a spindle.
229 */
230 struct dm_dev *origin_dev;
231
232 /*
233 * The faster of the two data devices. Typically an SSD.
234 */
235 struct dm_dev *cache_dev;
236
237 /*
238 * Size of the origin device in _complete_ blocks and native sectors.
239 */
240 dm_oblock_t origin_blocks;
241 sector_t origin_sectors;
242
243 /*
244 * Size of the cache device in blocks.
245 */
246 dm_cblock_t cache_size;
247
248 /*
249 * Fields for converting from sectors to blocks.
250 */
251 uint32_t sectors_per_block;
252 int sectors_per_block_shift;
253
254 spinlock_t lock;
255 struct list_head deferred_cells;
256 struct bio_list deferred_bios;
257 struct bio_list deferred_flush_bios;
258 struct bio_list deferred_writethrough_bios;
259 struct list_head quiesced_migrations;
260 struct list_head completed_migrations;
261 struct list_head need_commit_migrations;
262 sector_t migration_threshold;
263 wait_queue_head_t migration_wait;
264 atomic_t nr_allocated_migrations;
265
266 /*
267 * The number of in flight migrations that are performing
268 * background io. eg, promotion, writeback.
269 */
270 atomic_t nr_io_migrations;
271
272 wait_queue_head_t quiescing_wait;
273 atomic_t quiescing;
274 atomic_t quiescing_ack;
275
276 /*
277 * cache_size entries, dirty if set
278 */
279 atomic_t nr_dirty;
280 unsigned long *dirty_bitset;
281
282 /*
283 * origin_blocks entries, discarded if set.
284 */
285 dm_dblock_t discard_nr_blocks;
286 unsigned long *discard_bitset;
287 uint32_t discard_block_size; /* a power of 2 times sectors per block */
288
289 /*
290 * Rather than reconstructing the table line for the status we just
291 * save it and regurgitate.
292 */
293 unsigned nr_ctr_args;
294 const char **ctr_args;
295
296 struct dm_kcopyd_client *copier;
297 struct workqueue_struct *wq;
298 struct work_struct worker;
299
300 struct delayed_work waker;
301 unsigned long last_commit_jiffies;
302
303 struct dm_bio_prison *prison;
304 struct dm_deferred_set *all_io_ds;
305
306 mempool_t *migration_pool;
307
308 struct dm_cache_policy *policy;
309 unsigned policy_nr_args;
310
311 bool need_tick_bio:1;
312 bool sized:1;
313 bool invalidate:1;
314 bool commit_requested:1;
315 bool loaded_mappings:1;
316 bool loaded_discards:1;
317
318 /*
319 * Cache features such as write-through.
320 */
321 struct cache_features features;
322
323 struct cache_stats stats;
324
325 /*
326 * Invalidation fields.
327 */
328 spinlock_t invalidation_lock;
329 struct list_head invalidation_requests;
330
331 struct io_tracker origin_tracker;
332};
333
334struct per_bio_data {
335 bool tick:1;
336 unsigned req_nr:2;
337 struct dm_deferred_entry *all_io_entry;
338 struct dm_hook_info hook_info;
339 sector_t len;
340
341 /*
342 * writethrough fields. These MUST remain at the end of this
343 * structure and the 'cache' member must be the first as it
344 * is used to determine the offset of the writethrough fields.
345 */
346 struct cache *cache;
347 dm_cblock_t cblock;
348 struct dm_bio_details bio_details;
349};
350
351struct dm_cache_migration {
352 struct list_head list;
353 struct cache *cache;
354
355 unsigned long start_jiffies;
356 dm_oblock_t old_oblock;
357 dm_oblock_t new_oblock;
358 dm_cblock_t cblock;
359
360 bool err:1;
361 bool discard:1;
362 bool writeback:1;
363 bool demote:1;
364 bool promote:1;
365 bool requeue_holder:1;
366 bool invalidate:1;
367
368 struct dm_bio_prison_cell *old_ocell;
369 struct dm_bio_prison_cell *new_ocell;
370};
371
372/*
373 * Processing a bio in the worker thread may require these memory
374 * allocations. We prealloc to avoid deadlocks (the same worker thread
375 * frees them back to the mempool).
376 */
377struct prealloc {
378 struct dm_cache_migration *mg;
379 struct dm_bio_prison_cell *cell1;
380 struct dm_bio_prison_cell *cell2;
381};
382
383static enum cache_metadata_mode get_cache_mode(struct cache *cache);
384
385static void wake_worker(struct cache *cache)
386{
387 queue_work(cache->wq, &cache->worker);
388}
389
390/*----------------------------------------------------------------*/
391
392static struct dm_bio_prison_cell *alloc_prison_cell(struct cache *cache)
393{
394 /* FIXME: change to use a local slab. */
395 return dm_bio_prison_alloc_cell(cache->prison, GFP_NOWAIT);
396}
397
398static void free_prison_cell(struct cache *cache, struct dm_bio_prison_cell *cell)
399{
400 dm_bio_prison_free_cell(cache->prison, cell);
401}
402
403static struct dm_cache_migration *alloc_migration(struct cache *cache)
404{
405 struct dm_cache_migration *mg;
406
407 mg = mempool_alloc(cache->migration_pool, GFP_NOWAIT);
408 if (mg) {
409 mg->cache = cache;
410 atomic_inc(&mg->cache->nr_allocated_migrations);
411 }
412
413 return mg;
414}
415
416static void free_migration(struct dm_cache_migration *mg)
417{
418 struct cache *cache = mg->cache;
419
420 if (atomic_dec_and_test(&cache->nr_allocated_migrations))
421 wake_up(&cache->migration_wait);
422
423 mempool_free(mg, cache->migration_pool);
424}
425
426static int prealloc_data_structs(struct cache *cache, struct prealloc *p)
427{
428 if (!p->mg) {
429 p->mg = alloc_migration(cache);
430 if (!p->mg)
431 return -ENOMEM;
432 }
433
434 if (!p->cell1) {
435 p->cell1 = alloc_prison_cell(cache);
436 if (!p->cell1)
437 return -ENOMEM;
438 }
439
440 if (!p->cell2) {
441 p->cell2 = alloc_prison_cell(cache);
442 if (!p->cell2)
443 return -ENOMEM;
444 }
445
446 return 0;
447}
448
449static void prealloc_free_structs(struct cache *cache, struct prealloc *p)
450{
451 if (p->cell2)
452 free_prison_cell(cache, p->cell2);
453
454 if (p->cell1)
455 free_prison_cell(cache, p->cell1);
456
457 if (p->mg)
458 free_migration(p->mg);
459}
460
461static struct dm_cache_migration *prealloc_get_migration(struct prealloc *p)
462{
463 struct dm_cache_migration *mg = p->mg;
464
465 BUG_ON(!mg);
466 p->mg = NULL;
467
468 return mg;
469}
470
471/*
472 * You must have a cell within the prealloc struct to return. If not this
473 * function will BUG() rather than returning NULL.
474 */
475static struct dm_bio_prison_cell *prealloc_get_cell(struct prealloc *p)
476{
477 struct dm_bio_prison_cell *r = NULL;
478
479 if (p->cell1) {
480 r = p->cell1;
481 p->cell1 = NULL;
482
483 } else if (p->cell2) {
484 r = p->cell2;
485 p->cell2 = NULL;
486 } else
487 BUG();
488
489 return r;
490}
491
492/*
493 * You can't have more than two cells in a prealloc struct. BUG() will be
494 * called if you try and overfill.
495 */
496static void prealloc_put_cell(struct prealloc *p, struct dm_bio_prison_cell *cell)
497{
498 if (!p->cell2)
499 p->cell2 = cell;
500
501 else if (!p->cell1)
502 p->cell1 = cell;
503
504 else
505 BUG();
506}
507
508/*----------------------------------------------------------------*/
509
510static void build_key(dm_oblock_t begin, dm_oblock_t end, struct dm_cell_key *key)
511{
512 key->virtual = 0;
513 key->dev = 0;
514 key->block_begin = from_oblock(begin);
515 key->block_end = from_oblock(end);
516}
517
518/*
519 * The caller hands in a preallocated cell, and a free function for it.
520 * The cell will be freed if there's an error, or if it wasn't used because
521 * a cell with that key already exists.
522 */
523typedef void (*cell_free_fn)(void *context, struct dm_bio_prison_cell *cell);
524
525static int bio_detain_range(struct cache *cache, dm_oblock_t oblock_begin, dm_oblock_t oblock_end,
526 struct bio *bio, struct dm_bio_prison_cell *cell_prealloc,
527 cell_free_fn free_fn, void *free_context,
528 struct dm_bio_prison_cell **cell_result)
529{
530 int r;
531 struct dm_cell_key key;
532
533 build_key(oblock_begin, oblock_end, &key);
534 r = dm_bio_detain(cache->prison, &key, bio, cell_prealloc, cell_result);
535 if (r)
536 free_fn(free_context, cell_prealloc);
537
538 return r;
539}
540
541static int bio_detain(struct cache *cache, dm_oblock_t oblock,
542 struct bio *bio, struct dm_bio_prison_cell *cell_prealloc,
543 cell_free_fn free_fn, void *free_context,
544 struct dm_bio_prison_cell **cell_result)
545{
546 dm_oblock_t end = to_oblock(from_oblock(oblock) + 1ULL);
547 return bio_detain_range(cache, oblock, end, bio,
548 cell_prealloc, free_fn, free_context, cell_result);
549}
550
551static int get_cell(struct cache *cache,
552 dm_oblock_t oblock,
553 struct prealloc *structs,
554 struct dm_bio_prison_cell **cell_result)
555{
556 int r;
557 struct dm_cell_key key;
558 struct dm_bio_prison_cell *cell_prealloc;
559
560 cell_prealloc = prealloc_get_cell(structs);
561
562 build_key(oblock, to_oblock(from_oblock(oblock) + 1ULL), &key);
563 r = dm_get_cell(cache->prison, &key, cell_prealloc, cell_result);
564 if (r)
565 prealloc_put_cell(structs, cell_prealloc);
566
567 return r;
568}
569
570/*----------------------------------------------------------------*/
571
572static bool is_dirty(struct cache *cache, dm_cblock_t b)
573{
574 return test_bit(from_cblock(b), cache->dirty_bitset);
575}
576
577static void set_dirty(struct cache *cache, dm_oblock_t oblock, dm_cblock_t cblock)
578{
579 if (!test_and_set_bit(from_cblock(cblock), cache->dirty_bitset)) {
580 atomic_inc(&cache->nr_dirty);
581 policy_set_dirty(cache->policy, oblock);
582 }
583}
584
585static void clear_dirty(struct cache *cache, dm_oblock_t oblock, dm_cblock_t cblock)
586{
587 if (test_and_clear_bit(from_cblock(cblock), cache->dirty_bitset)) {
588 policy_clear_dirty(cache->policy, oblock);
589 if (atomic_dec_return(&cache->nr_dirty) == 0)
590 dm_table_event(cache->ti->table);
591 }
592}
593
594/*----------------------------------------------------------------*/
595
596static bool block_size_is_power_of_two(struct cache *cache)
597{
598 return cache->sectors_per_block_shift >= 0;
599}
600
601/* gcc on ARM generates spurious references to __udivdi3 and __umoddi3 */
602#if defined(CONFIG_ARM) && __GNUC__ == 4 && __GNUC_MINOR__ <= 6
603__always_inline
604#endif
605static dm_block_t block_div(dm_block_t b, uint32_t n)
606{
607 do_div(b, n);
608
609 return b;
610}
611
612static dm_block_t oblocks_per_dblock(struct cache *cache)
613{
614 dm_block_t oblocks = cache->discard_block_size;
615
616 if (block_size_is_power_of_two(cache))
617 oblocks >>= cache->sectors_per_block_shift;
618 else
619 oblocks = block_div(oblocks, cache->sectors_per_block);
620
621 return oblocks;
622}
623
624static dm_dblock_t oblock_to_dblock(struct cache *cache, dm_oblock_t oblock)
625{
626 return to_dblock(block_div(from_oblock(oblock),
627 oblocks_per_dblock(cache)));
628}
629
630static dm_oblock_t dblock_to_oblock(struct cache *cache, dm_dblock_t dblock)
631{
632 return to_oblock(from_dblock(dblock) * oblocks_per_dblock(cache));
633}
634
635static void set_discard(struct cache *cache, dm_dblock_t b)
636{
637 unsigned long flags;
638
639 BUG_ON(from_dblock(b) >= from_dblock(cache->discard_nr_blocks));
640 atomic_inc(&cache->stats.discard_count);
641
642 spin_lock_irqsave(&cache->lock, flags);
643 set_bit(from_dblock(b), cache->discard_bitset);
644 spin_unlock_irqrestore(&cache->lock, flags);
645}
646
647static void clear_discard(struct cache *cache, dm_dblock_t b)
648{
649 unsigned long flags;
650
651 spin_lock_irqsave(&cache->lock, flags);
652 clear_bit(from_dblock(b), cache->discard_bitset);
653 spin_unlock_irqrestore(&cache->lock, flags);
654}
655
656static bool is_discarded(struct cache *cache, dm_dblock_t b)
657{
658 int r;
659 unsigned long flags;
660
661 spin_lock_irqsave(&cache->lock, flags);
662 r = test_bit(from_dblock(b), cache->discard_bitset);
663 spin_unlock_irqrestore(&cache->lock, flags);
664
665 return r;
666}
667
668static bool is_discarded_oblock(struct cache *cache, dm_oblock_t b)
669{
670 int r;
671 unsigned long flags;
672
673 spin_lock_irqsave(&cache->lock, flags);
674 r = test_bit(from_dblock(oblock_to_dblock(cache, b)),
675 cache->discard_bitset);
676 spin_unlock_irqrestore(&cache->lock, flags);
677
678 return r;
679}
680
681/*----------------------------------------------------------------*/
682
683static void load_stats(struct cache *cache)
684{
685 struct dm_cache_statistics stats;
686
687 dm_cache_metadata_get_stats(cache->cmd, &stats);
688 atomic_set(&cache->stats.read_hit, stats.read_hits);
689 atomic_set(&cache->stats.read_miss, stats.read_misses);
690 atomic_set(&cache->stats.write_hit, stats.write_hits);
691 atomic_set(&cache->stats.write_miss, stats.write_misses);
692}
693
694static void save_stats(struct cache *cache)
695{
696 struct dm_cache_statistics stats;
697
698 if (get_cache_mode(cache) >= CM_READ_ONLY)
699 return;
700
701 stats.read_hits = atomic_read(&cache->stats.read_hit);
702 stats.read_misses = atomic_read(&cache->stats.read_miss);
703 stats.write_hits = atomic_read(&cache->stats.write_hit);
704 stats.write_misses = atomic_read(&cache->stats.write_miss);
705
706 dm_cache_metadata_set_stats(cache->cmd, &stats);
707}
708
709/*----------------------------------------------------------------
710 * Per bio data
711 *--------------------------------------------------------------*/
712
713/*
714 * If using writeback, leave out struct per_bio_data's writethrough fields.
715 */
716#define PB_DATA_SIZE_WB (offsetof(struct per_bio_data, cache))
717#define PB_DATA_SIZE_WT (sizeof(struct per_bio_data))
718
719static bool writethrough_mode(struct cache_features *f)
720{
721 return f->io_mode == CM_IO_WRITETHROUGH;
722}
723
724static bool writeback_mode(struct cache_features *f)
725{
726 return f->io_mode == CM_IO_WRITEBACK;
727}
728
729static bool passthrough_mode(struct cache_features *f)
730{
731 return f->io_mode == CM_IO_PASSTHROUGH;
732}
733
734static size_t get_per_bio_data_size(struct cache *cache)
735{
736 return writethrough_mode(&cache->features) ? PB_DATA_SIZE_WT : PB_DATA_SIZE_WB;
737}
738
739static struct per_bio_data *get_per_bio_data(struct bio *bio, size_t data_size)
740{
741 struct per_bio_data *pb = dm_per_bio_data(bio, data_size);
742 BUG_ON(!pb);
743 return pb;
744}
745
746static struct per_bio_data *init_per_bio_data(struct bio *bio, size_t data_size)
747{
748 struct per_bio_data *pb = get_per_bio_data(bio, data_size);
749
750 pb->tick = false;
751 pb->req_nr = dm_bio_get_target_bio_nr(bio);
752 pb->all_io_entry = NULL;
753 pb->len = 0;
754
755 return pb;
756}
757
758/*----------------------------------------------------------------
759 * Remapping
760 *--------------------------------------------------------------*/
761static void remap_to_origin(struct cache *cache, struct bio *bio)
762{
763 bio->bi_bdev = cache->origin_dev->bdev;
764}
765
766static void remap_to_cache(struct cache *cache, struct bio *bio,
767 dm_cblock_t cblock)
768{
769 sector_t bi_sector = bio->bi_iter.bi_sector;
770 sector_t block = from_cblock(cblock);
771
772 bio->bi_bdev = cache->cache_dev->bdev;
773 if (!block_size_is_power_of_two(cache))
774 bio->bi_iter.bi_sector =
775 (block * cache->sectors_per_block) +
776 sector_div(bi_sector, cache->sectors_per_block);
777 else
778 bio->bi_iter.bi_sector =
779 (block << cache->sectors_per_block_shift) |
780 (bi_sector & (cache->sectors_per_block - 1));
781}
782
783static void check_if_tick_bio_needed(struct cache *cache, struct bio *bio)
784{
785 unsigned long flags;
786 size_t pb_data_size = get_per_bio_data_size(cache);
787 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
788
789 spin_lock_irqsave(&cache->lock, flags);
790 if (cache->need_tick_bio &&
791 !(bio->bi_rw & (REQ_FUA | REQ_FLUSH | REQ_DISCARD))) {
792 pb->tick = true;
793 cache->need_tick_bio = false;
794 }
795 spin_unlock_irqrestore(&cache->lock, flags);
796}
797
798static void remap_to_origin_clear_discard(struct cache *cache, struct bio *bio,
799 dm_oblock_t oblock)
800{
801 check_if_tick_bio_needed(cache, bio);
802 remap_to_origin(cache, bio);
803 if (bio_data_dir(bio) == WRITE)
804 clear_discard(cache, oblock_to_dblock(cache, oblock));
805}
806
807static void remap_to_cache_dirty(struct cache *cache, struct bio *bio,
808 dm_oblock_t oblock, dm_cblock_t cblock)
809{
810 check_if_tick_bio_needed(cache, bio);
811 remap_to_cache(cache, bio, cblock);
812 if (bio_data_dir(bio) == WRITE) {
813 set_dirty(cache, oblock, cblock);
814 clear_discard(cache, oblock_to_dblock(cache, oblock));
815 }
816}
817
818static dm_oblock_t get_bio_block(struct cache *cache, struct bio *bio)
819{
820 sector_t block_nr = bio->bi_iter.bi_sector;
821
822 if (!block_size_is_power_of_two(cache))
823 (void) sector_div(block_nr, cache->sectors_per_block);
824 else
825 block_nr >>= cache->sectors_per_block_shift;
826
827 return to_oblock(block_nr);
828}
829
830static int bio_triggers_commit(struct cache *cache, struct bio *bio)
831{
832 return bio->bi_rw & (REQ_FLUSH | REQ_FUA);
833}
834
835/*
836 * You must increment the deferred set whilst the prison cell is held. To
837 * encourage this, we ask for 'cell' to be passed in.
838 */
839static void inc_ds(struct cache *cache, struct bio *bio,
840 struct dm_bio_prison_cell *cell)
841{
842 size_t pb_data_size = get_per_bio_data_size(cache);
843 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
844
845 BUG_ON(!cell);
846 BUG_ON(pb->all_io_entry);
847
848 pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
849}
850
851static bool accountable_bio(struct cache *cache, struct bio *bio)
852{
853 return ((bio->bi_bdev == cache->origin_dev->bdev) &&
854 !(bio->bi_rw & REQ_DISCARD));
855}
856
857static void accounted_begin(struct cache *cache, struct bio *bio)
858{
859 size_t pb_data_size = get_per_bio_data_size(cache);
860 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
861
862 if (accountable_bio(cache, bio)) {
863 pb->len = bio_sectors(bio);
864 iot_io_begin(&cache->origin_tracker, pb->len);
865 }
866}
867
868static void accounted_complete(struct cache *cache, struct bio *bio)
869{
870 size_t pb_data_size = get_per_bio_data_size(cache);
871 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
872
873 iot_io_end(&cache->origin_tracker, pb->len);
874}
875
876static void accounted_request(struct cache *cache, struct bio *bio)
877{
878 accounted_begin(cache, bio);
879 generic_make_request(bio);
880}
881
882static void issue(struct cache *cache, struct bio *bio)
883{
884 unsigned long flags;
885
886 if (!bio_triggers_commit(cache, bio)) {
887 accounted_request(cache, bio);
888 return;
889 }
890
891 /*
892 * Batch together any bios that trigger commits and then issue a
893 * single commit for them in do_worker().
894 */
895 spin_lock_irqsave(&cache->lock, flags);
896 cache->commit_requested = true;
897 bio_list_add(&cache->deferred_flush_bios, bio);
898 spin_unlock_irqrestore(&cache->lock, flags);
899}
900
901static void inc_and_issue(struct cache *cache, struct bio *bio, struct dm_bio_prison_cell *cell)
902{
903 inc_ds(cache, bio, cell);
904 issue(cache, bio);
905}
906
907static void defer_writethrough_bio(struct cache *cache, struct bio *bio)
908{
909 unsigned long flags;
910
911 spin_lock_irqsave(&cache->lock, flags);
912 bio_list_add(&cache->deferred_writethrough_bios, bio);
913 spin_unlock_irqrestore(&cache->lock, flags);
914
915 wake_worker(cache);
916}
917
918static void writethrough_endio(struct bio *bio)
919{
920 struct per_bio_data *pb = get_per_bio_data(bio, PB_DATA_SIZE_WT);
921
922 dm_unhook_bio(&pb->hook_info, bio);
923
924 if (bio->bi_error) {
925 bio_endio(bio);
926 return;
927 }
928
929 dm_bio_restore(&pb->bio_details, bio);
930 remap_to_cache(pb->cache, bio, pb->cblock);
931
932 /*
933 * We can't issue this bio directly, since we're in interrupt
934 * context. So it gets put on a bio list for processing by the
935 * worker thread.
936 */
937 defer_writethrough_bio(pb->cache, bio);
938}
939
940/*
941 * When running in writethrough mode we need to send writes to clean blocks
942 * to both the cache and origin devices. In future we'd like to clone the
943 * bio and send them in parallel, but for now we're doing them in
944 * series as this is easier.
945 */
946static void remap_to_origin_then_cache(struct cache *cache, struct bio *bio,
947 dm_oblock_t oblock, dm_cblock_t cblock)
948{
949 struct per_bio_data *pb = get_per_bio_data(bio, PB_DATA_SIZE_WT);
950
951 pb->cache = cache;
952 pb->cblock = cblock;
953 dm_hook_bio(&pb->hook_info, bio, writethrough_endio, NULL);
954 dm_bio_record(&pb->bio_details, bio);
955
956 remap_to_origin_clear_discard(pb->cache, bio, oblock);
957}
958
959/*----------------------------------------------------------------
960 * Failure modes
961 *--------------------------------------------------------------*/
962static enum cache_metadata_mode get_cache_mode(struct cache *cache)
963{
964 return cache->features.mode;
965}
966
967static const char *cache_device_name(struct cache *cache)
968{
969 return dm_device_name(dm_table_get_md(cache->ti->table));
970}
971
972static void notify_mode_switch(struct cache *cache, enum cache_metadata_mode mode)
973{
974 const char *descs[] = {
975 "write",
976 "read-only",
977 "fail"
978 };
979
980 dm_table_event(cache->ti->table);
981 DMINFO("%s: switching cache to %s mode",
982 cache_device_name(cache), descs[(int)mode]);
983}
984
985static void set_cache_mode(struct cache *cache, enum cache_metadata_mode new_mode)
986{
987 bool needs_check;
988 enum cache_metadata_mode old_mode = get_cache_mode(cache);
989
990 if (dm_cache_metadata_needs_check(cache->cmd, &needs_check)) {
991 DMERR("unable to read needs_check flag, setting failure mode");
992 new_mode = CM_FAIL;
993 }
994
995 if (new_mode == CM_WRITE && needs_check) {
996 DMERR("%s: unable to switch cache to write mode until repaired.",
997 cache_device_name(cache));
998 if (old_mode != new_mode)
999 new_mode = old_mode;
1000 else
1001 new_mode = CM_READ_ONLY;
1002 }
1003
1004 /* Never move out of fail mode */
1005 if (old_mode == CM_FAIL)
1006 new_mode = CM_FAIL;
1007
1008 switch (new_mode) {
1009 case CM_FAIL:
1010 case CM_READ_ONLY:
1011 dm_cache_metadata_set_read_only(cache->cmd);
1012 break;
1013
1014 case CM_WRITE:
1015 dm_cache_metadata_set_read_write(cache->cmd);
1016 break;
1017 }
1018
1019 cache->features.mode = new_mode;
1020
1021 if (new_mode != old_mode)
1022 notify_mode_switch(cache, new_mode);
1023}
1024
1025static void abort_transaction(struct cache *cache)
1026{
1027 const char *dev_name = cache_device_name(cache);
1028
1029 if (get_cache_mode(cache) >= CM_READ_ONLY)
1030 return;
1031
1032 if (dm_cache_metadata_set_needs_check(cache->cmd)) {
1033 DMERR("%s: failed to set 'needs_check' flag in metadata", dev_name);
1034 set_cache_mode(cache, CM_FAIL);
1035 }
1036
1037 DMERR_LIMIT("%s: aborting current metadata transaction", dev_name);
1038 if (dm_cache_metadata_abort(cache->cmd)) {
1039 DMERR("%s: failed to abort metadata transaction", dev_name);
1040 set_cache_mode(cache, CM_FAIL);
1041 }
1042}
1043
1044static void metadata_operation_failed(struct cache *cache, const char *op, int r)
1045{
1046 DMERR_LIMIT("%s: metadata operation '%s' failed: error = %d",
1047 cache_device_name(cache), op, r);
1048 abort_transaction(cache);
1049 set_cache_mode(cache, CM_READ_ONLY);
1050}
1051
1052/*----------------------------------------------------------------
1053 * Migration processing
1054 *
1055 * Migration covers moving data from the origin device to the cache, or
1056 * vice versa.
1057 *--------------------------------------------------------------*/
1058static void inc_io_migrations(struct cache *cache)
1059{
1060 atomic_inc(&cache->nr_io_migrations);
1061}
1062
1063static void dec_io_migrations(struct cache *cache)
1064{
1065 atomic_dec(&cache->nr_io_migrations);
1066}
1067
1068static bool discard_or_flush(struct bio *bio)
1069{
1070 return bio->bi_rw & (REQ_FLUSH | REQ_FUA | REQ_DISCARD);
1071}
1072
1073static void __cell_defer(struct cache *cache, struct dm_bio_prison_cell *cell)
1074{
1075 if (discard_or_flush(cell->holder)) {
1076 /*
1077 * We have to handle these bios individually.
1078 */
1079 dm_cell_release(cache->prison, cell, &cache->deferred_bios);
1080 free_prison_cell(cache, cell);
1081 } else
1082 list_add_tail(&cell->user_list, &cache->deferred_cells);
1083}
1084
1085static void cell_defer(struct cache *cache, struct dm_bio_prison_cell *cell, bool holder)
1086{
1087 unsigned long flags;
1088
1089 if (!holder && dm_cell_promote_or_release(cache->prison, cell)) {
1090 /*
1091 * There was no prisoner to promote to holder, the
1092 * cell has been released.
1093 */
1094 free_prison_cell(cache, cell);
1095 return;
1096 }
1097
1098 spin_lock_irqsave(&cache->lock, flags);
1099 __cell_defer(cache, cell);
1100 spin_unlock_irqrestore(&cache->lock, flags);
1101
1102 wake_worker(cache);
1103}
1104
1105static void cell_error_with_code(struct cache *cache, struct dm_bio_prison_cell *cell, int err)
1106{
1107 dm_cell_error(cache->prison, cell, err);
1108 free_prison_cell(cache, cell);
1109}
1110
1111static void cell_requeue(struct cache *cache, struct dm_bio_prison_cell *cell)
1112{
1113 cell_error_with_code(cache, cell, DM_ENDIO_REQUEUE);
1114}
1115
1116static void free_io_migration(struct dm_cache_migration *mg)
1117{
1118 struct cache *cache = mg->cache;
1119
1120 dec_io_migrations(cache);
1121 free_migration(mg);
1122 wake_worker(cache);
1123}
1124
1125static void migration_failure(struct dm_cache_migration *mg)
1126{
1127 struct cache *cache = mg->cache;
1128 const char *dev_name = cache_device_name(cache);
1129
1130 if (mg->writeback) {
1131 DMERR_LIMIT("%s: writeback failed; couldn't copy block", dev_name);
1132 set_dirty(cache, mg->old_oblock, mg->cblock);
1133 cell_defer(cache, mg->old_ocell, false);
1134
1135 } else if (mg->demote) {
1136 DMERR_LIMIT("%s: demotion failed; couldn't copy block", dev_name);
1137 policy_force_mapping(cache->policy, mg->new_oblock, mg->old_oblock);
1138
1139 cell_defer(cache, mg->old_ocell, mg->promote ? false : true);
1140 if (mg->promote)
1141 cell_defer(cache, mg->new_ocell, true);
1142 } else {
1143 DMERR_LIMIT("%s: promotion failed; couldn't copy block", dev_name);
1144 policy_remove_mapping(cache->policy, mg->new_oblock);
1145 cell_defer(cache, mg->new_ocell, true);
1146 }
1147
1148 free_io_migration(mg);
1149}
1150
1151static void migration_success_pre_commit(struct dm_cache_migration *mg)
1152{
1153 int r;
1154 unsigned long flags;
1155 struct cache *cache = mg->cache;
1156
1157 if (mg->writeback) {
1158 clear_dirty(cache, mg->old_oblock, mg->cblock);
1159 cell_defer(cache, mg->old_ocell, false);
1160 free_io_migration(mg);
1161 return;
1162
1163 } else if (mg->demote) {
1164 r = dm_cache_remove_mapping(cache->cmd, mg->cblock);
1165 if (r) {
1166 DMERR_LIMIT("%s: demotion failed; couldn't update on disk metadata",
1167 cache_device_name(cache));
1168 metadata_operation_failed(cache, "dm_cache_remove_mapping", r);
1169 policy_force_mapping(cache->policy, mg->new_oblock,
1170 mg->old_oblock);
1171 if (mg->promote)
1172 cell_defer(cache, mg->new_ocell, true);
1173 free_io_migration(mg);
1174 return;
1175 }
1176 } else {
1177 r = dm_cache_insert_mapping(cache->cmd, mg->cblock, mg->new_oblock);
1178 if (r) {
1179 DMERR_LIMIT("%s: promotion failed; couldn't update on disk metadata",
1180 cache_device_name(cache));
1181 metadata_operation_failed(cache, "dm_cache_insert_mapping", r);
1182 policy_remove_mapping(cache->policy, mg->new_oblock);
1183 free_io_migration(mg);
1184 return;
1185 }
1186 }
1187
1188 spin_lock_irqsave(&cache->lock, flags);
1189 list_add_tail(&mg->list, &cache->need_commit_migrations);
1190 cache->commit_requested = true;
1191 spin_unlock_irqrestore(&cache->lock, flags);
1192}
1193
1194static void migration_success_post_commit(struct dm_cache_migration *mg)
1195{
1196 unsigned long flags;
1197 struct cache *cache = mg->cache;
1198
1199 if (mg->writeback) {
1200 DMWARN_LIMIT("%s: writeback unexpectedly triggered commit",
1201 cache_device_name(cache));
1202 return;
1203
1204 } else if (mg->demote) {
1205 cell_defer(cache, mg->old_ocell, mg->promote ? false : true);
1206
1207 if (mg->promote) {
1208 mg->demote = false;
1209
1210 spin_lock_irqsave(&cache->lock, flags);
1211 list_add_tail(&mg->list, &cache->quiesced_migrations);
1212 spin_unlock_irqrestore(&cache->lock, flags);
1213
1214 } else {
1215 if (mg->invalidate)
1216 policy_remove_mapping(cache->policy, mg->old_oblock);
1217 free_io_migration(mg);
1218 }
1219
1220 } else {
1221 if (mg->requeue_holder) {
1222 clear_dirty(cache, mg->new_oblock, mg->cblock);
1223 cell_defer(cache, mg->new_ocell, true);
1224 } else {
1225 /*
1226 * The block was promoted via an overwrite, so it's dirty.
1227 */
1228 set_dirty(cache, mg->new_oblock, mg->cblock);
1229 bio_endio(mg->new_ocell->holder);
1230 cell_defer(cache, mg->new_ocell, false);
1231 }
1232 free_io_migration(mg);
1233 }
1234}
1235
1236static void copy_complete(int read_err, unsigned long write_err, void *context)
1237{
1238 unsigned long flags;
1239 struct dm_cache_migration *mg = (struct dm_cache_migration *) context;
1240 struct cache *cache = mg->cache;
1241
1242 if (read_err || write_err)
1243 mg->err = true;
1244
1245 spin_lock_irqsave(&cache->lock, flags);
1246 list_add_tail(&mg->list, &cache->completed_migrations);
1247 spin_unlock_irqrestore(&cache->lock, flags);
1248
1249 wake_worker(cache);
1250}
1251
1252static void issue_copy(struct dm_cache_migration *mg)
1253{
1254 int r;
1255 struct dm_io_region o_region, c_region;
1256 struct cache *cache = mg->cache;
1257 sector_t cblock = from_cblock(mg->cblock);
1258
1259 o_region.bdev = cache->origin_dev->bdev;
1260 o_region.count = cache->sectors_per_block;
1261
1262 c_region.bdev = cache->cache_dev->bdev;
1263 c_region.sector = cblock * cache->sectors_per_block;
1264 c_region.count = cache->sectors_per_block;
1265
1266 if (mg->writeback || mg->demote) {
1267 /* demote */
1268 o_region.sector = from_oblock(mg->old_oblock) * cache->sectors_per_block;
1269 r = dm_kcopyd_copy(cache->copier, &c_region, 1, &o_region, 0, copy_complete, mg);
1270 } else {
1271 /* promote */
1272 o_region.sector = from_oblock(mg->new_oblock) * cache->sectors_per_block;
1273 r = dm_kcopyd_copy(cache->copier, &o_region, 1, &c_region, 0, copy_complete, mg);
1274 }
1275
1276 if (r < 0) {
1277 DMERR_LIMIT("%s: issuing migration failed", cache_device_name(cache));
1278 migration_failure(mg);
1279 }
1280}
1281
1282static void overwrite_endio(struct bio *bio)
1283{
1284 struct dm_cache_migration *mg = bio->bi_private;
1285 struct cache *cache = mg->cache;
1286 size_t pb_data_size = get_per_bio_data_size(cache);
1287 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
1288 unsigned long flags;
1289
1290 dm_unhook_bio(&pb->hook_info, bio);
1291
1292 if (bio->bi_error)
1293 mg->err = true;
1294
1295 mg->requeue_holder = false;
1296
1297 spin_lock_irqsave(&cache->lock, flags);
1298 list_add_tail(&mg->list, &cache->completed_migrations);
1299 spin_unlock_irqrestore(&cache->lock, flags);
1300
1301 wake_worker(cache);
1302}
1303
1304static void issue_overwrite(struct dm_cache_migration *mg, struct bio *bio)
1305{
1306 size_t pb_data_size = get_per_bio_data_size(mg->cache);
1307 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
1308
1309 dm_hook_bio(&pb->hook_info, bio, overwrite_endio, mg);
1310 remap_to_cache_dirty(mg->cache, bio, mg->new_oblock, mg->cblock);
1311
1312 /*
1313 * No need to inc_ds() here, since the cell will be held for the
1314 * duration of the io.
1315 */
1316 accounted_request(mg->cache, bio);
1317}
1318
1319static bool bio_writes_complete_block(struct cache *cache, struct bio *bio)
1320{
1321 return (bio_data_dir(bio) == WRITE) &&
1322 (bio->bi_iter.bi_size == (cache->sectors_per_block << SECTOR_SHIFT));
1323}
1324
1325static void avoid_copy(struct dm_cache_migration *mg)
1326{
1327 atomic_inc(&mg->cache->stats.copies_avoided);
1328 migration_success_pre_commit(mg);
1329}
1330
1331static void calc_discard_block_range(struct cache *cache, struct bio *bio,
1332 dm_dblock_t *b, dm_dblock_t *e)
1333{
1334 sector_t sb = bio->bi_iter.bi_sector;
1335 sector_t se = bio_end_sector(bio);
1336
1337 *b = to_dblock(dm_sector_div_up(sb, cache->discard_block_size));
1338
1339 if (se - sb < cache->discard_block_size)
1340 *e = *b;
1341 else
1342 *e = to_dblock(block_div(se, cache->discard_block_size));
1343}
1344
1345static void issue_discard(struct dm_cache_migration *mg)
1346{
1347 dm_dblock_t b, e;
1348 struct bio *bio = mg->new_ocell->holder;
1349 struct cache *cache = mg->cache;
1350
1351 calc_discard_block_range(cache, bio, &b, &e);
1352 while (b != e) {
1353 set_discard(cache, b);
1354 b = to_dblock(from_dblock(b) + 1);
1355 }
1356
1357 bio_endio(bio);
1358 cell_defer(cache, mg->new_ocell, false);
1359 free_migration(mg);
1360 wake_worker(cache);
1361}
1362
1363static void issue_copy_or_discard(struct dm_cache_migration *mg)
1364{
1365 bool avoid;
1366 struct cache *cache = mg->cache;
1367
1368 if (mg->discard) {
1369 issue_discard(mg);
1370 return;
1371 }
1372
1373 if (mg->writeback || mg->demote)
1374 avoid = !is_dirty(cache, mg->cblock) ||
1375 is_discarded_oblock(cache, mg->old_oblock);
1376 else {
1377 struct bio *bio = mg->new_ocell->holder;
1378
1379 avoid = is_discarded_oblock(cache, mg->new_oblock);
1380
1381 if (writeback_mode(&cache->features) &&
1382 !avoid && bio_writes_complete_block(cache, bio)) {
1383 issue_overwrite(mg, bio);
1384 return;
1385 }
1386 }
1387
1388 avoid ? avoid_copy(mg) : issue_copy(mg);
1389}
1390
1391static void complete_migration(struct dm_cache_migration *mg)
1392{
1393 if (mg->err)
1394 migration_failure(mg);
1395 else
1396 migration_success_pre_commit(mg);
1397}
1398
1399static void process_migrations(struct cache *cache, struct list_head *head,
1400 void (*fn)(struct dm_cache_migration *))
1401{
1402 unsigned long flags;
1403 struct list_head list;
1404 struct dm_cache_migration *mg, *tmp;
1405
1406 INIT_LIST_HEAD(&list);
1407 spin_lock_irqsave(&cache->lock, flags);
1408 list_splice_init(head, &list);
1409 spin_unlock_irqrestore(&cache->lock, flags);
1410
1411 list_for_each_entry_safe(mg, tmp, &list, list)
1412 fn(mg);
1413}
1414
1415static void __queue_quiesced_migration(struct dm_cache_migration *mg)
1416{
1417 list_add_tail(&mg->list, &mg->cache->quiesced_migrations);
1418}
1419
1420static void queue_quiesced_migration(struct dm_cache_migration *mg)
1421{
1422 unsigned long flags;
1423 struct cache *cache = mg->cache;
1424
1425 spin_lock_irqsave(&cache->lock, flags);
1426 __queue_quiesced_migration(mg);
1427 spin_unlock_irqrestore(&cache->lock, flags);
1428
1429 wake_worker(cache);
1430}
1431
1432static void queue_quiesced_migrations(struct cache *cache, struct list_head *work)
1433{
1434 unsigned long flags;
1435 struct dm_cache_migration *mg, *tmp;
1436
1437 spin_lock_irqsave(&cache->lock, flags);
1438 list_for_each_entry_safe(mg, tmp, work, list)
1439 __queue_quiesced_migration(mg);
1440 spin_unlock_irqrestore(&cache->lock, flags);
1441
1442 wake_worker(cache);
1443}
1444
1445static void check_for_quiesced_migrations(struct cache *cache,
1446 struct per_bio_data *pb)
1447{
1448 struct list_head work;
1449
1450 if (!pb->all_io_entry)
1451 return;
1452
1453 INIT_LIST_HEAD(&work);
1454 dm_deferred_entry_dec(pb->all_io_entry, &work);
1455
1456 if (!list_empty(&work))
1457 queue_quiesced_migrations(cache, &work);
1458}
1459
1460static void quiesce_migration(struct dm_cache_migration *mg)
1461{
1462 if (!dm_deferred_set_add_work(mg->cache->all_io_ds, &mg->list))
1463 queue_quiesced_migration(mg);
1464}
1465
1466static void promote(struct cache *cache, struct prealloc *structs,
1467 dm_oblock_t oblock, dm_cblock_t cblock,
1468 struct dm_bio_prison_cell *cell)
1469{
1470 struct dm_cache_migration *mg = prealloc_get_migration(structs);
1471
1472 mg->err = false;
1473 mg->discard = false;
1474 mg->writeback = false;
1475 mg->demote = false;
1476 mg->promote = true;
1477 mg->requeue_holder = true;
1478 mg->invalidate = false;
1479 mg->cache = cache;
1480 mg->new_oblock = oblock;
1481 mg->cblock = cblock;
1482 mg->old_ocell = NULL;
1483 mg->new_ocell = cell;
1484 mg->start_jiffies = jiffies;
1485
1486 inc_io_migrations(cache);
1487 quiesce_migration(mg);
1488}
1489
1490static void writeback(struct cache *cache, struct prealloc *structs,
1491 dm_oblock_t oblock, dm_cblock_t cblock,
1492 struct dm_bio_prison_cell *cell)
1493{
1494 struct dm_cache_migration *mg = prealloc_get_migration(structs);
1495
1496 mg->err = false;
1497 mg->discard = false;
1498 mg->writeback = true;
1499 mg->demote = false;
1500 mg->promote = false;
1501 mg->requeue_holder = true;
1502 mg->invalidate = false;
1503 mg->cache = cache;
1504 mg->old_oblock = oblock;
1505 mg->cblock = cblock;
1506 mg->old_ocell = cell;
1507 mg->new_ocell = NULL;
1508 mg->start_jiffies = jiffies;
1509
1510 inc_io_migrations(cache);
1511 quiesce_migration(mg);
1512}
1513
1514static void demote_then_promote(struct cache *cache, struct prealloc *structs,
1515 dm_oblock_t old_oblock, dm_oblock_t new_oblock,
1516 dm_cblock_t cblock,
1517 struct dm_bio_prison_cell *old_ocell,
1518 struct dm_bio_prison_cell *new_ocell)
1519{
1520 struct dm_cache_migration *mg = prealloc_get_migration(structs);
1521
1522 mg->err = false;
1523 mg->discard = false;
1524 mg->writeback = false;
1525 mg->demote = true;
1526 mg->promote = true;
1527 mg->requeue_holder = true;
1528 mg->invalidate = false;
1529 mg->cache = cache;
1530 mg->old_oblock = old_oblock;
1531 mg->new_oblock = new_oblock;
1532 mg->cblock = cblock;
1533 mg->old_ocell = old_ocell;
1534 mg->new_ocell = new_ocell;
1535 mg->start_jiffies = jiffies;
1536
1537 inc_io_migrations(cache);
1538 quiesce_migration(mg);
1539}
1540
1541/*
1542 * Invalidate a cache entry. No writeback occurs; any changes in the cache
1543 * block are thrown away.
1544 */
1545static void invalidate(struct cache *cache, struct prealloc *structs,
1546 dm_oblock_t oblock, dm_cblock_t cblock,
1547 struct dm_bio_prison_cell *cell)
1548{
1549 struct dm_cache_migration *mg = prealloc_get_migration(structs);
1550
1551 mg->err = false;
1552 mg->discard = false;
1553 mg->writeback = false;
1554 mg->demote = true;
1555 mg->promote = false;
1556 mg->requeue_holder = true;
1557 mg->invalidate = true;
1558 mg->cache = cache;
1559 mg->old_oblock = oblock;
1560 mg->cblock = cblock;
1561 mg->old_ocell = cell;
1562 mg->new_ocell = NULL;
1563 mg->start_jiffies = jiffies;
1564
1565 inc_io_migrations(cache);
1566 quiesce_migration(mg);
1567}
1568
1569static void discard(struct cache *cache, struct prealloc *structs,
1570 struct dm_bio_prison_cell *cell)
1571{
1572 struct dm_cache_migration *mg = prealloc_get_migration(structs);
1573
1574 mg->err = false;
1575 mg->discard = true;
1576 mg->writeback = false;
1577 mg->demote = false;
1578 mg->promote = false;
1579 mg->requeue_holder = false;
1580 mg->invalidate = false;
1581 mg->cache = cache;
1582 mg->old_ocell = NULL;
1583 mg->new_ocell = cell;
1584 mg->start_jiffies = jiffies;
1585
1586 quiesce_migration(mg);
1587}
1588
1589/*----------------------------------------------------------------
1590 * bio processing
1591 *--------------------------------------------------------------*/
1592static void defer_bio(struct cache *cache, struct bio *bio)
1593{
1594 unsigned long flags;
1595
1596 spin_lock_irqsave(&cache->lock, flags);
1597 bio_list_add(&cache->deferred_bios, bio);
1598 spin_unlock_irqrestore(&cache->lock, flags);
1599
1600 wake_worker(cache);
1601}
1602
1603static void process_flush_bio(struct cache *cache, struct bio *bio)
1604{
1605 size_t pb_data_size = get_per_bio_data_size(cache);
1606 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
1607
1608 BUG_ON(bio->bi_iter.bi_size);
1609 if (!pb->req_nr)
1610 remap_to_origin(cache, bio);
1611 else
1612 remap_to_cache(cache, bio, 0);
1613
1614 /*
1615 * REQ_FLUSH is not directed at any particular block so we don't
1616 * need to inc_ds(). REQ_FUA's are split into a write + REQ_FLUSH
1617 * by dm-core.
1618 */
1619 issue(cache, bio);
1620}
1621
1622static void process_discard_bio(struct cache *cache, struct prealloc *structs,
1623 struct bio *bio)
1624{
1625 int r;
1626 dm_dblock_t b, e;
1627 struct dm_bio_prison_cell *cell_prealloc, *new_ocell;
1628
1629 calc_discard_block_range(cache, bio, &b, &e);
1630 if (b == e) {
1631 bio_endio(bio);
1632 return;
1633 }
1634
1635 cell_prealloc = prealloc_get_cell(structs);
1636 r = bio_detain_range(cache, dblock_to_oblock(cache, b), dblock_to_oblock(cache, e), bio, cell_prealloc,
1637 (cell_free_fn) prealloc_put_cell,
1638 structs, &new_ocell);
1639 if (r > 0)
1640 return;
1641
1642 discard(cache, structs, new_ocell);
1643}
1644
1645static bool spare_migration_bandwidth(struct cache *cache)
1646{
1647 sector_t current_volume = (atomic_read(&cache->nr_io_migrations) + 1) *
1648 cache->sectors_per_block;
1649 return current_volume < cache->migration_threshold;
1650}
1651
1652static void inc_hit_counter(struct cache *cache, struct bio *bio)
1653{
1654 atomic_inc(bio_data_dir(bio) == READ ?
1655 &cache->stats.read_hit : &cache->stats.write_hit);
1656}
1657
1658static void inc_miss_counter(struct cache *cache, struct bio *bio)
1659{
1660 atomic_inc(bio_data_dir(bio) == READ ?
1661 &cache->stats.read_miss : &cache->stats.write_miss);
1662}
1663
1664/*----------------------------------------------------------------*/
1665
1666struct inc_detail {
1667 struct cache *cache;
1668 struct bio_list bios_for_issue;
1669 struct bio_list unhandled_bios;
1670 bool any_writes;
1671};
1672
1673static void inc_fn(void *context, struct dm_bio_prison_cell *cell)
1674{
1675 struct bio *bio;
1676 struct inc_detail *detail = context;
1677 struct cache *cache = detail->cache;
1678
1679 inc_ds(cache, cell->holder, cell);
1680 if (bio_data_dir(cell->holder) == WRITE)
1681 detail->any_writes = true;
1682
1683 while ((bio = bio_list_pop(&cell->bios))) {
1684 if (discard_or_flush(bio)) {
1685 bio_list_add(&detail->unhandled_bios, bio);
1686 continue;
1687 }
1688
1689 if (bio_data_dir(bio) == WRITE)
1690 detail->any_writes = true;
1691
1692 bio_list_add(&detail->bios_for_issue, bio);
1693 inc_ds(cache, bio, cell);
1694 }
1695}
1696
1697// FIXME: refactor these two
1698static void remap_cell_to_origin_clear_discard(struct cache *cache,
1699 struct dm_bio_prison_cell *cell,
1700 dm_oblock_t oblock, bool issue_holder)
1701{
1702 struct bio *bio;
1703 unsigned long flags;
1704 struct inc_detail detail;
1705
1706 detail.cache = cache;
1707 bio_list_init(&detail.bios_for_issue);
1708 bio_list_init(&detail.unhandled_bios);
1709 detail.any_writes = false;
1710
1711 spin_lock_irqsave(&cache->lock, flags);
1712 dm_cell_visit_release(cache->prison, inc_fn, &detail, cell);
1713 bio_list_merge(&cache->deferred_bios, &detail.unhandled_bios);
1714 spin_unlock_irqrestore(&cache->lock, flags);
1715
1716 remap_to_origin(cache, cell->holder);
1717 if (issue_holder)
1718 issue(cache, cell->holder);
1719 else
1720 accounted_begin(cache, cell->holder);
1721
1722 if (detail.any_writes)
1723 clear_discard(cache, oblock_to_dblock(cache, oblock));
1724
1725 while ((bio = bio_list_pop(&detail.bios_for_issue))) {
1726 remap_to_origin(cache, bio);
1727 issue(cache, bio);
1728 }
1729
1730 free_prison_cell(cache, cell);
1731}
1732
1733static void remap_cell_to_cache_dirty(struct cache *cache, struct dm_bio_prison_cell *cell,
1734 dm_oblock_t oblock, dm_cblock_t cblock, bool issue_holder)
1735{
1736 struct bio *bio;
1737 unsigned long flags;
1738 struct inc_detail detail;
1739
1740 detail.cache = cache;
1741 bio_list_init(&detail.bios_for_issue);
1742 bio_list_init(&detail.unhandled_bios);
1743 detail.any_writes = false;
1744
1745 spin_lock_irqsave(&cache->lock, flags);
1746 dm_cell_visit_release(cache->prison, inc_fn, &detail, cell);
1747 bio_list_merge(&cache->deferred_bios, &detail.unhandled_bios);
1748 spin_unlock_irqrestore(&cache->lock, flags);
1749
1750 remap_to_cache(cache, cell->holder, cblock);
1751 if (issue_holder)
1752 issue(cache, cell->holder);
1753 else
1754 accounted_begin(cache, cell->holder);
1755
1756 if (detail.any_writes) {
1757 set_dirty(cache, oblock, cblock);
1758 clear_discard(cache, oblock_to_dblock(cache, oblock));
1759 }
1760
1761 while ((bio = bio_list_pop(&detail.bios_for_issue))) {
1762 remap_to_cache(cache, bio, cblock);
1763 issue(cache, bio);
1764 }
1765
1766 free_prison_cell(cache, cell);
1767}
1768
1769/*----------------------------------------------------------------*/
1770
1771struct old_oblock_lock {
1772 struct policy_locker locker;
1773 struct cache *cache;
1774 struct prealloc *structs;
1775 struct dm_bio_prison_cell *cell;
1776};
1777
1778static int null_locker(struct policy_locker *locker, dm_oblock_t b)
1779{
1780 /* This should never be called */
1781 BUG();
1782 return 0;
1783}
1784
1785static int cell_locker(struct policy_locker *locker, dm_oblock_t b)
1786{
1787 struct old_oblock_lock *l = container_of(locker, struct old_oblock_lock, locker);
1788 struct dm_bio_prison_cell *cell_prealloc = prealloc_get_cell(l->structs);
1789
1790 return bio_detain(l->cache, b, NULL, cell_prealloc,
1791 (cell_free_fn) prealloc_put_cell,
1792 l->structs, &l->cell);
1793}
1794
1795static void process_cell(struct cache *cache, struct prealloc *structs,
1796 struct dm_bio_prison_cell *new_ocell)
1797{
1798 int r;
1799 bool release_cell = true;
1800 struct bio *bio = new_ocell->holder;
1801 dm_oblock_t block = get_bio_block(cache, bio);
1802 struct policy_result lookup_result;
1803 bool passthrough = passthrough_mode(&cache->features);
1804 bool fast_promotion, can_migrate;
1805 struct old_oblock_lock ool;
1806
1807 fast_promotion = is_discarded_oblock(cache, block) || bio_writes_complete_block(cache, bio);
1808 can_migrate = !passthrough && (fast_promotion || spare_migration_bandwidth(cache));
1809
1810 ool.locker.fn = cell_locker;
1811 ool.cache = cache;
1812 ool.structs = structs;
1813 ool.cell = NULL;
1814 r = policy_map(cache->policy, block, true, can_migrate, fast_promotion,
1815 bio, &ool.locker, &lookup_result);
1816
1817 if (r == -EWOULDBLOCK)
1818 /* migration has been denied */
1819 lookup_result.op = POLICY_MISS;
1820
1821 switch (lookup_result.op) {
1822 case POLICY_HIT:
1823 if (passthrough) {
1824 inc_miss_counter(cache, bio);
1825
1826 /*
1827 * Passthrough always maps to the origin,
1828 * invalidating any cache blocks that are written
1829 * to.
1830 */
1831
1832 if (bio_data_dir(bio) == WRITE) {
1833 atomic_inc(&cache->stats.demotion);
1834 invalidate(cache, structs, block, lookup_result.cblock, new_ocell);
1835 release_cell = false;
1836
1837 } else {
1838 /* FIXME: factor out issue_origin() */
1839 remap_to_origin_clear_discard(cache, bio, block);
1840 inc_and_issue(cache, bio, new_ocell);
1841 }
1842 } else {
1843 inc_hit_counter(cache, bio);
1844
1845 if (bio_data_dir(bio) == WRITE &&
1846 writethrough_mode(&cache->features) &&
1847 !is_dirty(cache, lookup_result.cblock)) {
1848 remap_to_origin_then_cache(cache, bio, block, lookup_result.cblock);
1849 inc_and_issue(cache, bio, new_ocell);
1850
1851 } else {
1852 remap_cell_to_cache_dirty(cache, new_ocell, block, lookup_result.cblock, true);
1853 release_cell = false;
1854 }
1855 }
1856
1857 break;
1858
1859 case POLICY_MISS:
1860 inc_miss_counter(cache, bio);
1861 remap_cell_to_origin_clear_discard(cache, new_ocell, block, true);
1862 release_cell = false;
1863 break;
1864
1865 case POLICY_NEW:
1866 atomic_inc(&cache->stats.promotion);
1867 promote(cache, structs, block, lookup_result.cblock, new_ocell);
1868 release_cell = false;
1869 break;
1870
1871 case POLICY_REPLACE:
1872 atomic_inc(&cache->stats.demotion);
1873 atomic_inc(&cache->stats.promotion);
1874 demote_then_promote(cache, structs, lookup_result.old_oblock,
1875 block, lookup_result.cblock,
1876 ool.cell, new_ocell);
1877 release_cell = false;
1878 break;
1879
1880 default:
1881 DMERR_LIMIT("%s: %s: erroring bio, unknown policy op: %u",
1882 cache_device_name(cache), __func__,
1883 (unsigned) lookup_result.op);
1884 bio_io_error(bio);
1885 }
1886
1887 if (release_cell)
1888 cell_defer(cache, new_ocell, false);
1889}
1890
1891static void process_bio(struct cache *cache, struct prealloc *structs,
1892 struct bio *bio)
1893{
1894 int r;
1895 dm_oblock_t block = get_bio_block(cache, bio);
1896 struct dm_bio_prison_cell *cell_prealloc, *new_ocell;
1897
1898 /*
1899 * Check to see if that block is currently migrating.
1900 */
1901 cell_prealloc = prealloc_get_cell(structs);
1902 r = bio_detain(cache, block, bio, cell_prealloc,
1903 (cell_free_fn) prealloc_put_cell,
1904 structs, &new_ocell);
1905 if (r > 0)
1906 return;
1907
1908 process_cell(cache, structs, new_ocell);
1909}
1910
1911static int need_commit_due_to_time(struct cache *cache)
1912{
1913 return jiffies < cache->last_commit_jiffies ||
1914 jiffies > cache->last_commit_jiffies + COMMIT_PERIOD;
1915}
1916
1917/*
1918 * A non-zero return indicates read_only or fail_io mode.
1919 */
1920static int commit(struct cache *cache, bool clean_shutdown)
1921{
1922 int r;
1923
1924 if (get_cache_mode(cache) >= CM_READ_ONLY)
1925 return -EINVAL;
1926
1927 atomic_inc(&cache->stats.commit_count);
1928 r = dm_cache_commit(cache->cmd, clean_shutdown);
1929 if (r)
1930 metadata_operation_failed(cache, "dm_cache_commit", r);
1931
1932 return r;
1933}
1934
1935static int commit_if_needed(struct cache *cache)
1936{
1937 int r = 0;
1938
1939 if ((cache->commit_requested || need_commit_due_to_time(cache)) &&
1940 dm_cache_changed_this_transaction(cache->cmd)) {
1941 r = commit(cache, false);
1942 cache->commit_requested = false;
1943 cache->last_commit_jiffies = jiffies;
1944 }
1945
1946 return r;
1947}
1948
1949static void process_deferred_bios(struct cache *cache)
1950{
1951 bool prealloc_used = false;
1952 unsigned long flags;
1953 struct bio_list bios;
1954 struct bio *bio;
1955 struct prealloc structs;
1956
1957 memset(&structs, 0, sizeof(structs));
1958 bio_list_init(&bios);
1959
1960 spin_lock_irqsave(&cache->lock, flags);
1961 bio_list_merge(&bios, &cache->deferred_bios);
1962 bio_list_init(&cache->deferred_bios);
1963 spin_unlock_irqrestore(&cache->lock, flags);
1964
1965 while (!bio_list_empty(&bios)) {
1966 /*
1967 * If we've got no free migration structs, and processing
1968 * this bio might require one, we pause until there are some
1969 * prepared mappings to process.
1970 */
1971 prealloc_used = true;
1972 if (prealloc_data_structs(cache, &structs)) {
1973 spin_lock_irqsave(&cache->lock, flags);
1974 bio_list_merge(&cache->deferred_bios, &bios);
1975 spin_unlock_irqrestore(&cache->lock, flags);
1976 break;
1977 }
1978
1979 bio = bio_list_pop(&bios);
1980
1981 if (bio->bi_rw & REQ_FLUSH)
1982 process_flush_bio(cache, bio);
1983 else if (bio->bi_rw & REQ_DISCARD)
1984 process_discard_bio(cache, &structs, bio);
1985 else
1986 process_bio(cache, &structs, bio);
1987 }
1988
1989 if (prealloc_used)
1990 prealloc_free_structs(cache, &structs);
1991}
1992
1993static void process_deferred_cells(struct cache *cache)
1994{
1995 bool prealloc_used = false;
1996 unsigned long flags;
1997 struct dm_bio_prison_cell *cell, *tmp;
1998 struct list_head cells;
1999 struct prealloc structs;
2000
2001 memset(&structs, 0, sizeof(structs));
2002
2003 INIT_LIST_HEAD(&cells);
2004
2005 spin_lock_irqsave(&cache->lock, flags);
2006 list_splice_init(&cache->deferred_cells, &cells);
2007 spin_unlock_irqrestore(&cache->lock, flags);
2008
2009 list_for_each_entry_safe(cell, tmp, &cells, user_list) {
2010 /*
2011 * If we've got no free migration structs, and processing
2012 * this bio might require one, we pause until there are some
2013 * prepared mappings to process.
2014 */
2015 prealloc_used = true;
2016 if (prealloc_data_structs(cache, &structs)) {
2017 spin_lock_irqsave(&cache->lock, flags);
2018 list_splice(&cells, &cache->deferred_cells);
2019 spin_unlock_irqrestore(&cache->lock, flags);
2020 break;
2021 }
2022
2023 process_cell(cache, &structs, cell);
2024 }
2025
2026 if (prealloc_used)
2027 prealloc_free_structs(cache, &structs);
2028}
2029
2030static void process_deferred_flush_bios(struct cache *cache, bool submit_bios)
2031{
2032 unsigned long flags;
2033 struct bio_list bios;
2034 struct bio *bio;
2035
2036 bio_list_init(&bios);
2037
2038 spin_lock_irqsave(&cache->lock, flags);
2039 bio_list_merge(&bios, &cache->deferred_flush_bios);
2040 bio_list_init(&cache->deferred_flush_bios);
2041 spin_unlock_irqrestore(&cache->lock, flags);
2042
2043 /*
2044 * These bios have already been through inc_ds()
2045 */
2046 while ((bio = bio_list_pop(&bios)))
2047 submit_bios ? accounted_request(cache, bio) : bio_io_error(bio);
2048}
2049
2050static void process_deferred_writethrough_bios(struct cache *cache)
2051{
2052 unsigned long flags;
2053 struct bio_list bios;
2054 struct bio *bio;
2055
2056 bio_list_init(&bios);
2057
2058 spin_lock_irqsave(&cache->lock, flags);
2059 bio_list_merge(&bios, &cache->deferred_writethrough_bios);
2060 bio_list_init(&cache->deferred_writethrough_bios);
2061 spin_unlock_irqrestore(&cache->lock, flags);
2062
2063 /*
2064 * These bios have already been through inc_ds()
2065 */
2066 while ((bio = bio_list_pop(&bios)))
2067 accounted_request(cache, bio);
2068}
2069
2070static void writeback_some_dirty_blocks(struct cache *cache)
2071{
2072 bool prealloc_used = false;
2073 dm_oblock_t oblock;
2074 dm_cblock_t cblock;
2075 struct prealloc structs;
2076 struct dm_bio_prison_cell *old_ocell;
2077 bool busy = !iot_idle_for(&cache->origin_tracker, HZ);
2078
2079 memset(&structs, 0, sizeof(structs));
2080
2081 while (spare_migration_bandwidth(cache)) {
2082 if (policy_writeback_work(cache->policy, &oblock, &cblock, busy))
2083 break; /* no work to do */
2084
2085 prealloc_used = true;
2086 if (prealloc_data_structs(cache, &structs) ||
2087 get_cell(cache, oblock, &structs, &old_ocell)) {
2088 policy_set_dirty(cache->policy, oblock);
2089 break;
2090 }
2091
2092 writeback(cache, &structs, oblock, cblock, old_ocell);
2093 }
2094
2095 if (prealloc_used)
2096 prealloc_free_structs(cache, &structs);
2097}
2098
2099/*----------------------------------------------------------------
2100 * Invalidations.
2101 * Dropping something from the cache *without* writing back.
2102 *--------------------------------------------------------------*/
2103
2104static void process_invalidation_request(struct cache *cache, struct invalidation_request *req)
2105{
2106 int r = 0;
2107 uint64_t begin = from_cblock(req->cblocks->begin);
2108 uint64_t end = from_cblock(req->cblocks->end);
2109
2110 while (begin != end) {
2111 r = policy_remove_cblock(cache->policy, to_cblock(begin));
2112 if (!r) {
2113 r = dm_cache_remove_mapping(cache->cmd, to_cblock(begin));
2114 if (r) {
2115 metadata_operation_failed(cache, "dm_cache_remove_mapping", r);
2116 break;
2117 }
2118
2119 } else if (r == -ENODATA) {
2120 /* harmless, already unmapped */
2121 r = 0;
2122
2123 } else {
2124 DMERR("%s: policy_remove_cblock failed", cache_device_name(cache));
2125 break;
2126 }
2127
2128 begin++;
2129 }
2130
2131 cache->commit_requested = true;
2132
2133 req->err = r;
2134 atomic_set(&req->complete, 1);
2135
2136 wake_up(&req->result_wait);
2137}
2138
2139static void process_invalidation_requests(struct cache *cache)
2140{
2141 struct list_head list;
2142 struct invalidation_request *req, *tmp;
2143
2144 INIT_LIST_HEAD(&list);
2145 spin_lock(&cache->invalidation_lock);
2146 list_splice_init(&cache->invalidation_requests, &list);
2147 spin_unlock(&cache->invalidation_lock);
2148
2149 list_for_each_entry_safe (req, tmp, &list, list)
2150 process_invalidation_request(cache, req);
2151}
2152
2153/*----------------------------------------------------------------
2154 * Main worker loop
2155 *--------------------------------------------------------------*/
2156static bool is_quiescing(struct cache *cache)
2157{
2158 return atomic_read(&cache->quiescing);
2159}
2160
2161static void ack_quiescing(struct cache *cache)
2162{
2163 if (is_quiescing(cache)) {
2164 atomic_inc(&cache->quiescing_ack);
2165 wake_up(&cache->quiescing_wait);
2166 }
2167}
2168
2169static void wait_for_quiescing_ack(struct cache *cache)
2170{
2171 wait_event(cache->quiescing_wait, atomic_read(&cache->quiescing_ack));
2172}
2173
2174static void start_quiescing(struct cache *cache)
2175{
2176 atomic_inc(&cache->quiescing);
2177 wait_for_quiescing_ack(cache);
2178}
2179
2180static void stop_quiescing(struct cache *cache)
2181{
2182 atomic_set(&cache->quiescing, 0);
2183 atomic_set(&cache->quiescing_ack, 0);
2184}
2185
2186static void wait_for_migrations(struct cache *cache)
2187{
2188 wait_event(cache->migration_wait, !atomic_read(&cache->nr_allocated_migrations));
2189}
2190
2191static void stop_worker(struct cache *cache)
2192{
2193 cancel_delayed_work(&cache->waker);
2194 flush_workqueue(cache->wq);
2195}
2196
2197static void requeue_deferred_cells(struct cache *cache)
2198{
2199 unsigned long flags;
2200 struct list_head cells;
2201 struct dm_bio_prison_cell *cell, *tmp;
2202
2203 INIT_LIST_HEAD(&cells);
2204 spin_lock_irqsave(&cache->lock, flags);
2205 list_splice_init(&cache->deferred_cells, &cells);
2206 spin_unlock_irqrestore(&cache->lock, flags);
2207
2208 list_for_each_entry_safe(cell, tmp, &cells, user_list)
2209 cell_requeue(cache, cell);
2210}
2211
2212static void requeue_deferred_bios(struct cache *cache)
2213{
2214 struct bio *bio;
2215 struct bio_list bios;
2216
2217 bio_list_init(&bios);
2218 bio_list_merge(&bios, &cache->deferred_bios);
2219 bio_list_init(&cache->deferred_bios);
2220
2221 while ((bio = bio_list_pop(&bios))) {
2222 bio->bi_error = DM_ENDIO_REQUEUE;
2223 bio_endio(bio);
2224 }
2225}
2226
2227static int more_work(struct cache *cache)
2228{
2229 if (is_quiescing(cache))
2230 return !list_empty(&cache->quiesced_migrations) ||
2231 !list_empty(&cache->completed_migrations) ||
2232 !list_empty(&cache->need_commit_migrations);
2233 else
2234 return !bio_list_empty(&cache->deferred_bios) ||
2235 !list_empty(&cache->deferred_cells) ||
2236 !bio_list_empty(&cache->deferred_flush_bios) ||
2237 !bio_list_empty(&cache->deferred_writethrough_bios) ||
2238 !list_empty(&cache->quiesced_migrations) ||
2239 !list_empty(&cache->completed_migrations) ||
2240 !list_empty(&cache->need_commit_migrations) ||
2241 cache->invalidate;
2242}
2243
2244static void do_worker(struct work_struct *ws)
2245{
2246 struct cache *cache = container_of(ws, struct cache, worker);
2247
2248 do {
2249 if (!is_quiescing(cache)) {
2250 writeback_some_dirty_blocks(cache);
2251 process_deferred_writethrough_bios(cache);
2252 process_deferred_bios(cache);
2253 process_deferred_cells(cache);
2254 process_invalidation_requests(cache);
2255 }
2256
2257 process_migrations(cache, &cache->quiesced_migrations, issue_copy_or_discard);
2258 process_migrations(cache, &cache->completed_migrations, complete_migration);
2259
2260 if (commit_if_needed(cache)) {
2261 process_deferred_flush_bios(cache, false);
2262 process_migrations(cache, &cache->need_commit_migrations, migration_failure);
2263 } else {
2264 process_deferred_flush_bios(cache, true);
2265 process_migrations(cache, &cache->need_commit_migrations,
2266 migration_success_post_commit);
2267 }
2268
2269 ack_quiescing(cache);
2270
2271 } while (more_work(cache));
2272}
2273
2274/*
2275 * We want to commit periodically so that not too much
2276 * unwritten metadata builds up.
2277 */
2278static void do_waker(struct work_struct *ws)
2279{
2280 struct cache *cache = container_of(to_delayed_work(ws), struct cache, waker);
2281 policy_tick(cache->policy, true);
2282 wake_worker(cache);
2283 queue_delayed_work(cache->wq, &cache->waker, COMMIT_PERIOD);
2284}
2285
2286/*----------------------------------------------------------------*/
2287
2288static int is_congested(struct dm_dev *dev, int bdi_bits)
2289{
2290 struct request_queue *q = bdev_get_queue(dev->bdev);
2291 return bdi_congested(&q->backing_dev_info, bdi_bits);
2292}
2293
2294static int cache_is_congested(struct dm_target_callbacks *cb, int bdi_bits)
2295{
2296 struct cache *cache = container_of(cb, struct cache, callbacks);
2297
2298 return is_congested(cache->origin_dev, bdi_bits) ||
2299 is_congested(cache->cache_dev, bdi_bits);
2300}
2301
2302/*----------------------------------------------------------------
2303 * Target methods
2304 *--------------------------------------------------------------*/
2305
2306/*
2307 * This function gets called on the error paths of the constructor, so we
2308 * have to cope with a partially initialised struct.
2309 */
2310static void destroy(struct cache *cache)
2311{
2312 unsigned i;
2313
2314 mempool_destroy(cache->migration_pool);
2315
2316 if (cache->all_io_ds)
2317 dm_deferred_set_destroy(cache->all_io_ds);
2318
2319 if (cache->prison)
2320 dm_bio_prison_destroy(cache->prison);
2321
2322 if (cache->wq)
2323 destroy_workqueue(cache->wq);
2324
2325 if (cache->dirty_bitset)
2326 free_bitset(cache->dirty_bitset);
2327
2328 if (cache->discard_bitset)
2329 free_bitset(cache->discard_bitset);
2330
2331 if (cache->copier)
2332 dm_kcopyd_client_destroy(cache->copier);
2333
2334 if (cache->cmd)
2335 dm_cache_metadata_close(cache->cmd);
2336
2337 if (cache->metadata_dev)
2338 dm_put_device(cache->ti, cache->metadata_dev);
2339
2340 if (cache->origin_dev)
2341 dm_put_device(cache->ti, cache->origin_dev);
2342
2343 if (cache->cache_dev)
2344 dm_put_device(cache->ti, cache->cache_dev);
2345
2346 if (cache->policy)
2347 dm_cache_policy_destroy(cache->policy);
2348
2349 for (i = 0; i < cache->nr_ctr_args ; i++)
2350 kfree(cache->ctr_args[i]);
2351 kfree(cache->ctr_args);
2352
2353 kfree(cache);
2354}
2355
2356static void cache_dtr(struct dm_target *ti)
2357{
2358 struct cache *cache = ti->private;
2359
2360 destroy(cache);
2361}
2362
2363static sector_t get_dev_size(struct dm_dev *dev)
2364{
2365 return i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT;
2366}
2367
2368/*----------------------------------------------------------------*/
2369
2370/*
2371 * Construct a cache device mapping.
2372 *
2373 * cache <metadata dev> <cache dev> <origin dev> <block size>
2374 * <#feature args> [<feature arg>]*
2375 * <policy> <#policy args> [<policy arg>]*
2376 *
2377 * metadata dev : fast device holding the persistent metadata
2378 * cache dev : fast device holding cached data blocks
2379 * origin dev : slow device holding original data blocks
2380 * block size : cache unit size in sectors
2381 *
2382 * #feature args : number of feature arguments passed
2383 * feature args : writethrough. (The default is writeback.)
2384 *
2385 * policy : the replacement policy to use
2386 * #policy args : an even number of policy arguments corresponding
2387 * to key/value pairs passed to the policy
2388 * policy args : key/value pairs passed to the policy
2389 * E.g. 'sequential_threshold 1024'
2390 * See cache-policies.txt for details.
2391 *
2392 * Optional feature arguments are:
2393 * writethrough : write through caching that prohibits cache block
2394 * content from being different from origin block content.
2395 * Without this argument, the default behaviour is to write
2396 * back cache block contents later for performance reasons,
2397 * so they may differ from the corresponding origin blocks.
2398 */
2399struct cache_args {
2400 struct dm_target *ti;
2401
2402 struct dm_dev *metadata_dev;
2403
2404 struct dm_dev *cache_dev;
2405 sector_t cache_sectors;
2406
2407 struct dm_dev *origin_dev;
2408 sector_t origin_sectors;
2409
2410 uint32_t block_size;
2411
2412 const char *policy_name;
2413 int policy_argc;
2414 const char **policy_argv;
2415
2416 struct cache_features features;
2417};
2418
2419static void destroy_cache_args(struct cache_args *ca)
2420{
2421 if (ca->metadata_dev)
2422 dm_put_device(ca->ti, ca->metadata_dev);
2423
2424 if (ca->cache_dev)
2425 dm_put_device(ca->ti, ca->cache_dev);
2426
2427 if (ca->origin_dev)
2428 dm_put_device(ca->ti, ca->origin_dev);
2429
2430 kfree(ca);
2431}
2432
2433static bool at_least_one_arg(struct dm_arg_set *as, char **error)
2434{
2435 if (!as->argc) {
2436 *error = "Insufficient args";
2437 return false;
2438 }
2439
2440 return true;
2441}
2442
2443static int parse_metadata_dev(struct cache_args *ca, struct dm_arg_set *as,
2444 char **error)
2445{
2446 int r;
2447 sector_t metadata_dev_size;
2448 char b[BDEVNAME_SIZE];
2449
2450 if (!at_least_one_arg(as, error))
2451 return -EINVAL;
2452
2453 r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
2454 &ca->metadata_dev);
2455 if (r) {
2456 *error = "Error opening metadata device";
2457 return r;
2458 }
2459
2460 metadata_dev_size = get_dev_size(ca->metadata_dev);
2461 if (metadata_dev_size > DM_CACHE_METADATA_MAX_SECTORS_WARNING)
2462 DMWARN("Metadata device %s is larger than %u sectors: excess space will not be used.",
2463 bdevname(ca->metadata_dev->bdev, b), THIN_METADATA_MAX_SECTORS);
2464
2465 return 0;
2466}
2467
2468static int parse_cache_dev(struct cache_args *ca, struct dm_arg_set *as,
2469 char **error)
2470{
2471 int r;
2472
2473 if (!at_least_one_arg(as, error))
2474 return -EINVAL;
2475
2476 r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
2477 &ca->cache_dev);
2478 if (r) {
2479 *error = "Error opening cache device";
2480 return r;
2481 }
2482 ca->cache_sectors = get_dev_size(ca->cache_dev);
2483
2484 return 0;
2485}
2486
2487static int parse_origin_dev(struct cache_args *ca, struct dm_arg_set *as,
2488 char **error)
2489{
2490 int r;
2491
2492 if (!at_least_one_arg(as, error))
2493 return -EINVAL;
2494
2495 r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
2496 &ca->origin_dev);
2497 if (r) {
2498 *error = "Error opening origin device";
2499 return r;
2500 }
2501
2502 ca->origin_sectors = get_dev_size(ca->origin_dev);
2503 if (ca->ti->len > ca->origin_sectors) {
2504 *error = "Device size larger than cached device";
2505 return -EINVAL;
2506 }
2507
2508 return 0;
2509}
2510
2511static int parse_block_size(struct cache_args *ca, struct dm_arg_set *as,
2512 char **error)
2513{
2514 unsigned long block_size;
2515
2516 if (!at_least_one_arg(as, error))
2517 return -EINVAL;
2518
2519 if (kstrtoul(dm_shift_arg(as), 10, &block_size) || !block_size ||
2520 block_size < DATA_DEV_BLOCK_SIZE_MIN_SECTORS ||
2521 block_size > DATA_DEV_BLOCK_SIZE_MAX_SECTORS ||
2522 block_size & (DATA_DEV_BLOCK_SIZE_MIN_SECTORS - 1)) {
2523 *error = "Invalid data block size";
2524 return -EINVAL;
2525 }
2526
2527 if (block_size > ca->cache_sectors) {
2528 *error = "Data block size is larger than the cache device";
2529 return -EINVAL;
2530 }
2531
2532 ca->block_size = block_size;
2533
2534 return 0;
2535}
2536
2537static void init_features(struct cache_features *cf)
2538{
2539 cf->mode = CM_WRITE;
2540 cf->io_mode = CM_IO_WRITEBACK;
2541}
2542
2543static int parse_features(struct cache_args *ca, struct dm_arg_set *as,
2544 char **error)
2545{
2546 static struct dm_arg _args[] = {
2547 {0, 1, "Invalid number of cache feature arguments"},
2548 };
2549
2550 int r;
2551 unsigned argc;
2552 const char *arg;
2553 struct cache_features *cf = &ca->features;
2554
2555 init_features(cf);
2556
2557 r = dm_read_arg_group(_args, as, &argc, error);
2558 if (r)
2559 return -EINVAL;
2560
2561 while (argc--) {
2562 arg = dm_shift_arg(as);
2563
2564 if (!strcasecmp(arg, "writeback"))
2565 cf->io_mode = CM_IO_WRITEBACK;
2566
2567 else if (!strcasecmp(arg, "writethrough"))
2568 cf->io_mode = CM_IO_WRITETHROUGH;
2569
2570 else if (!strcasecmp(arg, "passthrough"))
2571 cf->io_mode = CM_IO_PASSTHROUGH;
2572
2573 else {
2574 *error = "Unrecognised cache feature requested";
2575 return -EINVAL;
2576 }
2577 }
2578
2579 return 0;
2580}
2581
2582static int parse_policy(struct cache_args *ca, struct dm_arg_set *as,
2583 char **error)
2584{
2585 static struct dm_arg _args[] = {
2586 {0, 1024, "Invalid number of policy arguments"},
2587 };
2588
2589 int r;
2590
2591 if (!at_least_one_arg(as, error))
2592 return -EINVAL;
2593
2594 ca->policy_name = dm_shift_arg(as);
2595
2596 r = dm_read_arg_group(_args, as, &ca->policy_argc, error);
2597 if (r)
2598 return -EINVAL;
2599
2600 ca->policy_argv = (const char **)as->argv;
2601 dm_consume_args(as, ca->policy_argc);
2602
2603 return 0;
2604}
2605
2606static int parse_cache_args(struct cache_args *ca, int argc, char **argv,
2607 char **error)
2608{
2609 int r;
2610 struct dm_arg_set as;
2611
2612 as.argc = argc;
2613 as.argv = argv;
2614
2615 r = parse_metadata_dev(ca, &as, error);
2616 if (r)
2617 return r;
2618
2619 r = parse_cache_dev(ca, &as, error);
2620 if (r)
2621 return r;
2622
2623 r = parse_origin_dev(ca, &as, error);
2624 if (r)
2625 return r;
2626
2627 r = parse_block_size(ca, &as, error);
2628 if (r)
2629 return r;
2630
2631 r = parse_features(ca, &as, error);
2632 if (r)
2633 return r;
2634
2635 r = parse_policy(ca, &as, error);
2636 if (r)
2637 return r;
2638
2639 return 0;
2640}
2641
2642/*----------------------------------------------------------------*/
2643
2644static struct kmem_cache *migration_cache;
2645
2646#define NOT_CORE_OPTION 1
2647
2648static int process_config_option(struct cache *cache, const char *key, const char *value)
2649{
2650 unsigned long tmp;
2651
2652 if (!strcasecmp(key, "migration_threshold")) {
2653 if (kstrtoul(value, 10, &tmp))
2654 return -EINVAL;
2655
2656 cache->migration_threshold = tmp;
2657 return 0;
2658 }
2659
2660 return NOT_CORE_OPTION;
2661}
2662
2663static int set_config_value(struct cache *cache, const char *key, const char *value)
2664{
2665 int r = process_config_option(cache, key, value);
2666
2667 if (r == NOT_CORE_OPTION)
2668 r = policy_set_config_value(cache->policy, key, value);
2669
2670 if (r)
2671 DMWARN("bad config value for %s: %s", key, value);
2672
2673 return r;
2674}
2675
2676static int set_config_values(struct cache *cache, int argc, const char **argv)
2677{
2678 int r = 0;
2679
2680 if (argc & 1) {
2681 DMWARN("Odd number of policy arguments given but they should be <key> <value> pairs.");
2682 return -EINVAL;
2683 }
2684
2685 while (argc) {
2686 r = set_config_value(cache, argv[0], argv[1]);
2687 if (r)
2688 break;
2689
2690 argc -= 2;
2691 argv += 2;
2692 }
2693
2694 return r;
2695}
2696
2697static int create_cache_policy(struct cache *cache, struct cache_args *ca,
2698 char **error)
2699{
2700 struct dm_cache_policy *p = dm_cache_policy_create(ca->policy_name,
2701 cache->cache_size,
2702 cache->origin_sectors,
2703 cache->sectors_per_block);
2704 if (IS_ERR(p)) {
2705 *error = "Error creating cache's policy";
2706 return PTR_ERR(p);
2707 }
2708 cache->policy = p;
2709
2710 return 0;
2711}
2712
2713/*
2714 * We want the discard block size to be at least the size of the cache
2715 * block size and have no more than 2^14 discard blocks across the origin.
2716 */
2717#define MAX_DISCARD_BLOCKS (1 << 14)
2718
2719static bool too_many_discard_blocks(sector_t discard_block_size,
2720 sector_t origin_size)
2721{
2722 (void) sector_div(origin_size, discard_block_size);
2723
2724 return origin_size > MAX_DISCARD_BLOCKS;
2725}
2726
2727static sector_t calculate_discard_block_size(sector_t cache_block_size,
2728 sector_t origin_size)
2729{
2730 sector_t discard_block_size = cache_block_size;
2731
2732 if (origin_size)
2733 while (too_many_discard_blocks(discard_block_size, origin_size))
2734 discard_block_size *= 2;
2735
2736 return discard_block_size;
2737}
2738
2739static void set_cache_size(struct cache *cache, dm_cblock_t size)
2740{
2741 dm_block_t nr_blocks = from_cblock(size);
2742
2743 if (nr_blocks > (1 << 20) && cache->cache_size != size)
2744 DMWARN_LIMIT("You have created a cache device with a lot of individual cache blocks (%llu)\n"
2745 "All these mappings can consume a lot of kernel memory, and take some time to read/write.\n"
2746 "Please consider increasing the cache block size to reduce the overall cache block count.",
2747 (unsigned long long) nr_blocks);
2748
2749 cache->cache_size = size;
2750}
2751
2752#define DEFAULT_MIGRATION_THRESHOLD 2048
2753
2754static int cache_create(struct cache_args *ca, struct cache **result)
2755{
2756 int r = 0;
2757 char **error = &ca->ti->error;
2758 struct cache *cache;
2759 struct dm_target *ti = ca->ti;
2760 dm_block_t origin_blocks;
2761 struct dm_cache_metadata *cmd;
2762 bool may_format = ca->features.mode == CM_WRITE;
2763
2764 cache = kzalloc(sizeof(*cache), GFP_KERNEL);
2765 if (!cache)
2766 return -ENOMEM;
2767
2768 cache->ti = ca->ti;
2769 ti->private = cache;
2770 ti->num_flush_bios = 2;
2771 ti->flush_supported = true;
2772
2773 ti->num_discard_bios = 1;
2774 ti->discards_supported = true;
2775 ti->discard_zeroes_data_unsupported = true;
2776 ti->split_discard_bios = false;
2777
2778 cache->features = ca->features;
2779 ti->per_io_data_size = get_per_bio_data_size(cache);
2780
2781 cache->callbacks.congested_fn = cache_is_congested;
2782 dm_table_add_target_callbacks(ti->table, &cache->callbacks);
2783
2784 cache->metadata_dev = ca->metadata_dev;
2785 cache->origin_dev = ca->origin_dev;
2786 cache->cache_dev = ca->cache_dev;
2787
2788 ca->metadata_dev = ca->origin_dev = ca->cache_dev = NULL;
2789
2790 /* FIXME: factor out this whole section */
2791 origin_blocks = cache->origin_sectors = ca->origin_sectors;
2792 origin_blocks = block_div(origin_blocks, ca->block_size);
2793 cache->origin_blocks = to_oblock(origin_blocks);
2794
2795 cache->sectors_per_block = ca->block_size;
2796 if (dm_set_target_max_io_len(ti, cache->sectors_per_block)) {
2797 r = -EINVAL;
2798 goto bad;
2799 }
2800
2801 if (ca->block_size & (ca->block_size - 1)) {
2802 dm_block_t cache_size = ca->cache_sectors;
2803
2804 cache->sectors_per_block_shift = -1;
2805 cache_size = block_div(cache_size, ca->block_size);
2806 set_cache_size(cache, to_cblock(cache_size));
2807 } else {
2808 cache->sectors_per_block_shift = __ffs(ca->block_size);
2809 set_cache_size(cache, to_cblock(ca->cache_sectors >> cache->sectors_per_block_shift));
2810 }
2811
2812 r = create_cache_policy(cache, ca, error);
2813 if (r)
2814 goto bad;
2815
2816 cache->policy_nr_args = ca->policy_argc;
2817 cache->migration_threshold = DEFAULT_MIGRATION_THRESHOLD;
2818
2819 r = set_config_values(cache, ca->policy_argc, ca->policy_argv);
2820 if (r) {
2821 *error = "Error setting cache policy's config values";
2822 goto bad;
2823 }
2824
2825 cmd = dm_cache_metadata_open(cache->metadata_dev->bdev,
2826 ca->block_size, may_format,
2827 dm_cache_policy_get_hint_size(cache->policy));
2828 if (IS_ERR(cmd)) {
2829 *error = "Error creating metadata object";
2830 r = PTR_ERR(cmd);
2831 goto bad;
2832 }
2833 cache->cmd = cmd;
2834 set_cache_mode(cache, CM_WRITE);
2835 if (get_cache_mode(cache) != CM_WRITE) {
2836 *error = "Unable to get write access to metadata, please check/repair metadata.";
2837 r = -EINVAL;
2838 goto bad;
2839 }
2840
2841 if (passthrough_mode(&cache->features)) {
2842 bool all_clean;
2843
2844 r = dm_cache_metadata_all_clean(cache->cmd, &all_clean);
2845 if (r) {
2846 *error = "dm_cache_metadata_all_clean() failed";
2847 goto bad;
2848 }
2849
2850 if (!all_clean) {
2851 *error = "Cannot enter passthrough mode unless all blocks are clean";
2852 r = -EINVAL;
2853 goto bad;
2854 }
2855 }
2856
2857 spin_lock_init(&cache->lock);
2858 INIT_LIST_HEAD(&cache->deferred_cells);
2859 bio_list_init(&cache->deferred_bios);
2860 bio_list_init(&cache->deferred_flush_bios);
2861 bio_list_init(&cache->deferred_writethrough_bios);
2862 INIT_LIST_HEAD(&cache->quiesced_migrations);
2863 INIT_LIST_HEAD(&cache->completed_migrations);
2864 INIT_LIST_HEAD(&cache->need_commit_migrations);
2865 atomic_set(&cache->nr_allocated_migrations, 0);
2866 atomic_set(&cache->nr_io_migrations, 0);
2867 init_waitqueue_head(&cache->migration_wait);
2868
2869 init_waitqueue_head(&cache->quiescing_wait);
2870 atomic_set(&cache->quiescing, 0);
2871 atomic_set(&cache->quiescing_ack, 0);
2872
2873 r = -ENOMEM;
2874 atomic_set(&cache->nr_dirty, 0);
2875 cache->dirty_bitset = alloc_bitset(from_cblock(cache->cache_size));
2876 if (!cache->dirty_bitset) {
2877 *error = "could not allocate dirty bitset";
2878 goto bad;
2879 }
2880 clear_bitset(cache->dirty_bitset, from_cblock(cache->cache_size));
2881
2882 cache->discard_block_size =
2883 calculate_discard_block_size(cache->sectors_per_block,
2884 cache->origin_sectors);
2885 cache->discard_nr_blocks = to_dblock(dm_sector_div_up(cache->origin_sectors,
2886 cache->discard_block_size));
2887 cache->discard_bitset = alloc_bitset(from_dblock(cache->discard_nr_blocks));
2888 if (!cache->discard_bitset) {
2889 *error = "could not allocate discard bitset";
2890 goto bad;
2891 }
2892 clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks));
2893
2894 cache->copier = dm_kcopyd_client_create(&dm_kcopyd_throttle);
2895 if (IS_ERR(cache->copier)) {
2896 *error = "could not create kcopyd client";
2897 r = PTR_ERR(cache->copier);
2898 goto bad;
2899 }
2900
2901 cache->wq = alloc_ordered_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM);
2902 if (!cache->wq) {
2903 *error = "could not create workqueue for metadata object";
2904 goto bad;
2905 }
2906 INIT_WORK(&cache->worker, do_worker);
2907 INIT_DELAYED_WORK(&cache->waker, do_waker);
2908 cache->last_commit_jiffies = jiffies;
2909
2910 cache->prison = dm_bio_prison_create();
2911 if (!cache->prison) {
2912 *error = "could not create bio prison";
2913 goto bad;
2914 }
2915
2916 cache->all_io_ds = dm_deferred_set_create();
2917 if (!cache->all_io_ds) {
2918 *error = "could not create all_io deferred set";
2919 goto bad;
2920 }
2921
2922 cache->migration_pool = mempool_create_slab_pool(MIGRATION_POOL_SIZE,
2923 migration_cache);
2924 if (!cache->migration_pool) {
2925 *error = "Error creating cache's migration mempool";
2926 goto bad;
2927 }
2928
2929 cache->need_tick_bio = true;
2930 cache->sized = false;
2931 cache->invalidate = false;
2932 cache->commit_requested = false;
2933 cache->loaded_mappings = false;
2934 cache->loaded_discards = false;
2935
2936 load_stats(cache);
2937
2938 atomic_set(&cache->stats.demotion, 0);
2939 atomic_set(&cache->stats.promotion, 0);
2940 atomic_set(&cache->stats.copies_avoided, 0);
2941 atomic_set(&cache->stats.cache_cell_clash, 0);
2942 atomic_set(&cache->stats.commit_count, 0);
2943 atomic_set(&cache->stats.discard_count, 0);
2944
2945 spin_lock_init(&cache->invalidation_lock);
2946 INIT_LIST_HEAD(&cache->invalidation_requests);
2947
2948 iot_init(&cache->origin_tracker);
2949
2950 *result = cache;
2951 return 0;
2952
2953bad:
2954 destroy(cache);
2955 return r;
2956}
2957
2958static int copy_ctr_args(struct cache *cache, int argc, const char **argv)
2959{
2960 unsigned i;
2961 const char **copy;
2962
2963 copy = kcalloc(argc, sizeof(*copy), GFP_KERNEL);
2964 if (!copy)
2965 return -ENOMEM;
2966 for (i = 0; i < argc; i++) {
2967 copy[i] = kstrdup(argv[i], GFP_KERNEL);
2968 if (!copy[i]) {
2969 while (i--)
2970 kfree(copy[i]);
2971 kfree(copy);
2972 return -ENOMEM;
2973 }
2974 }
2975
2976 cache->nr_ctr_args = argc;
2977 cache->ctr_args = copy;
2978
2979 return 0;
2980}
2981
2982static int cache_ctr(struct dm_target *ti, unsigned argc, char **argv)
2983{
2984 int r = -EINVAL;
2985 struct cache_args *ca;
2986 struct cache *cache = NULL;
2987
2988 ca = kzalloc(sizeof(*ca), GFP_KERNEL);
2989 if (!ca) {
2990 ti->error = "Error allocating memory for cache";
2991 return -ENOMEM;
2992 }
2993 ca->ti = ti;
2994
2995 r = parse_cache_args(ca, argc, argv, &ti->error);
2996 if (r)
2997 goto out;
2998
2999 r = cache_create(ca, &cache);
3000 if (r)
3001 goto out;
3002
3003 r = copy_ctr_args(cache, argc - 3, (const char **)argv + 3);
3004 if (r) {
3005 destroy(cache);
3006 goto out;
3007 }
3008
3009 ti->private = cache;
3010
3011out:
3012 destroy_cache_args(ca);
3013 return r;
3014}
3015
3016/*----------------------------------------------------------------*/
3017
3018static int cache_map(struct dm_target *ti, struct bio *bio)
3019{
3020 struct cache *cache = ti->private;
3021
3022 int r;
3023 struct dm_bio_prison_cell *cell = NULL;
3024 dm_oblock_t block = get_bio_block(cache, bio);
3025 size_t pb_data_size = get_per_bio_data_size(cache);
3026 bool can_migrate = false;
3027 bool fast_promotion;
3028 struct policy_result lookup_result;
3029 struct per_bio_data *pb = init_per_bio_data(bio, pb_data_size);
3030 struct old_oblock_lock ool;
3031
3032 ool.locker.fn = null_locker;
3033
3034 if (unlikely(from_oblock(block) >= from_oblock(cache->origin_blocks))) {
3035 /*
3036 * This can only occur if the io goes to a partial block at
3037 * the end of the origin device. We don't cache these.
3038 * Just remap to the origin and carry on.
3039 */
3040 remap_to_origin(cache, bio);
3041 accounted_begin(cache, bio);
3042 return DM_MAPIO_REMAPPED;
3043 }
3044
3045 if (discard_or_flush(bio)) {
3046 defer_bio(cache, bio);
3047 return DM_MAPIO_SUBMITTED;
3048 }
3049
3050 /*
3051 * Check to see if that block is currently migrating.
3052 */
3053 cell = alloc_prison_cell(cache);
3054 if (!cell) {
3055 defer_bio(cache, bio);
3056 return DM_MAPIO_SUBMITTED;
3057 }
3058
3059 r = bio_detain(cache, block, bio, cell,
3060 (cell_free_fn) free_prison_cell,
3061 cache, &cell);
3062 if (r) {
3063 if (r < 0)
3064 defer_bio(cache, bio);
3065
3066 return DM_MAPIO_SUBMITTED;
3067 }
3068
3069 fast_promotion = is_discarded_oblock(cache, block) || bio_writes_complete_block(cache, bio);
3070
3071 r = policy_map(cache->policy, block, false, can_migrate, fast_promotion,
3072 bio, &ool.locker, &lookup_result);
3073 if (r == -EWOULDBLOCK) {
3074 cell_defer(cache, cell, true);
3075 return DM_MAPIO_SUBMITTED;
3076
3077 } else if (r) {
3078 DMERR_LIMIT("%s: Unexpected return from cache replacement policy: %d",
3079 cache_device_name(cache), r);
3080 cell_defer(cache, cell, false);
3081 bio_io_error(bio);
3082 return DM_MAPIO_SUBMITTED;
3083 }
3084
3085 r = DM_MAPIO_REMAPPED;
3086 switch (lookup_result.op) {
3087 case POLICY_HIT:
3088 if (passthrough_mode(&cache->features)) {
3089 if (bio_data_dir(bio) == WRITE) {
3090 /*
3091 * We need to invalidate this block, so
3092 * defer for the worker thread.
3093 */
3094 cell_defer(cache, cell, true);
3095 r = DM_MAPIO_SUBMITTED;
3096
3097 } else {
3098 inc_miss_counter(cache, bio);
3099 remap_to_origin_clear_discard(cache, bio, block);
3100 accounted_begin(cache, bio);
3101 inc_ds(cache, bio, cell);
3102 // FIXME: we want to remap hits or misses straight
3103 // away rather than passing over to the worker.
3104 cell_defer(cache, cell, false);
3105 }
3106
3107 } else {
3108 inc_hit_counter(cache, bio);
3109 if (bio_data_dir(bio) == WRITE && writethrough_mode(&cache->features) &&
3110 !is_dirty(cache, lookup_result.cblock)) {
3111 remap_to_origin_then_cache(cache, bio, block, lookup_result.cblock);
3112 accounted_begin(cache, bio);
3113 inc_ds(cache, bio, cell);
3114 cell_defer(cache, cell, false);
3115
3116 } else
3117 remap_cell_to_cache_dirty(cache, cell, block, lookup_result.cblock, false);
3118 }
3119 break;
3120
3121 case POLICY_MISS:
3122 inc_miss_counter(cache, bio);
3123 if (pb->req_nr != 0) {
3124 /*
3125 * This is a duplicate writethrough io that is no
3126 * longer needed because the block has been demoted.
3127 */
3128 bio_endio(bio);
3129 // FIXME: remap everything as a miss
3130 cell_defer(cache, cell, false);
3131 r = DM_MAPIO_SUBMITTED;
3132
3133 } else
3134 remap_cell_to_origin_clear_discard(cache, cell, block, false);
3135 break;
3136
3137 default:
3138 DMERR_LIMIT("%s: %s: erroring bio: unknown policy op: %u",
3139 cache_device_name(cache), __func__,
3140 (unsigned) lookup_result.op);
3141 cell_defer(cache, cell, false);
3142 bio_io_error(bio);
3143 r = DM_MAPIO_SUBMITTED;
3144 }
3145
3146 return r;
3147}
3148
3149static int cache_end_io(struct dm_target *ti, struct bio *bio, int error)
3150{
3151 struct cache *cache = ti->private;
3152 unsigned long flags;
3153 size_t pb_data_size = get_per_bio_data_size(cache);
3154 struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);
3155
3156 if (pb->tick) {
3157 policy_tick(cache->policy, false);
3158
3159 spin_lock_irqsave(&cache->lock, flags);
3160 cache->need_tick_bio = true;
3161 spin_unlock_irqrestore(&cache->lock, flags);
3162 }
3163
3164 check_for_quiesced_migrations(cache, pb);
3165 accounted_complete(cache, bio);
3166
3167 return 0;
3168}
3169
3170static int write_dirty_bitset(struct cache *cache)
3171{
3172 unsigned i, r;
3173
3174 if (get_cache_mode(cache) >= CM_READ_ONLY)
3175 return -EINVAL;
3176
3177 for (i = 0; i < from_cblock(cache->cache_size); i++) {
3178 r = dm_cache_set_dirty(cache->cmd, to_cblock(i),
3179 is_dirty(cache, to_cblock(i)));
3180 if (r) {
3181 metadata_operation_failed(cache, "dm_cache_set_dirty", r);
3182 return r;
3183 }
3184 }
3185
3186 return 0;
3187}
3188
3189static int write_discard_bitset(struct cache *cache)
3190{
3191 unsigned i, r;
3192
3193 if (get_cache_mode(cache) >= CM_READ_ONLY)
3194 return -EINVAL;
3195
3196 r = dm_cache_discard_bitset_resize(cache->cmd, cache->discard_block_size,
3197 cache->discard_nr_blocks);
3198 if (r) {
3199 DMERR("%s: could not resize on-disk discard bitset", cache_device_name(cache));
3200 metadata_operation_failed(cache, "dm_cache_discard_bitset_resize", r);
3201 return r;
3202 }
3203
3204 for (i = 0; i < from_dblock(cache->discard_nr_blocks); i++) {
3205 r = dm_cache_set_discard(cache->cmd, to_dblock(i),
3206 is_discarded(cache, to_dblock(i)));
3207 if (r) {
3208 metadata_operation_failed(cache, "dm_cache_set_discard", r);
3209 return r;
3210 }
3211 }
3212
3213 return 0;
3214}
3215
3216static int write_hints(struct cache *cache)
3217{
3218 int r;
3219
3220 if (get_cache_mode(cache) >= CM_READ_ONLY)
3221 return -EINVAL;
3222
3223 r = dm_cache_write_hints(cache->cmd, cache->policy);
3224 if (r) {
3225 metadata_operation_failed(cache, "dm_cache_write_hints", r);
3226 return r;
3227 }
3228
3229 return 0;
3230}
3231
3232/*
3233 * returns true on success
3234 */
3235static bool sync_metadata(struct cache *cache)
3236{
3237 int r1, r2, r3, r4;
3238
3239 r1 = write_dirty_bitset(cache);
3240 if (r1)
3241 DMERR("%s: could not write dirty bitset", cache_device_name(cache));
3242
3243 r2 = write_discard_bitset(cache);
3244 if (r2)
3245 DMERR("%s: could not write discard bitset", cache_device_name(cache));
3246
3247 save_stats(cache);
3248
3249 r3 = write_hints(cache);
3250 if (r3)
3251 DMERR("%s: could not write hints", cache_device_name(cache));
3252
3253 /*
3254 * If writing the above metadata failed, we still commit, but don't
3255 * set the clean shutdown flag. This will effectively force every
3256 * dirty bit to be set on reload.
3257 */
3258 r4 = commit(cache, !r1 && !r2 && !r3);
3259 if (r4)
3260 DMERR("%s: could not write cache metadata", cache_device_name(cache));
3261
3262 return !r1 && !r2 && !r3 && !r4;
3263}
3264
3265static void cache_postsuspend(struct dm_target *ti)
3266{
3267 struct cache *cache = ti->private;
3268
3269 start_quiescing(cache);
3270 wait_for_migrations(cache);
3271 stop_worker(cache);
3272 requeue_deferred_bios(cache);
3273 requeue_deferred_cells(cache);
3274 stop_quiescing(cache);
3275
3276 if (get_cache_mode(cache) == CM_WRITE)
3277 (void) sync_metadata(cache);
3278}
3279
3280static int load_mapping(void *context, dm_oblock_t oblock, dm_cblock_t cblock,
3281 bool dirty, uint32_t hint, bool hint_valid)
3282{
3283 int r;
3284 struct cache *cache = context;
3285
3286 r = policy_load_mapping(cache->policy, oblock, cblock, hint, hint_valid);
3287 if (r)
3288 return r;
3289
3290 if (dirty)
3291 set_dirty(cache, oblock, cblock);
3292 else
3293 clear_dirty(cache, oblock, cblock);
3294
3295 return 0;
3296}
3297
3298/*
3299 * The discard block size in the on disk metadata is not
3300 * neccessarily the same as we're currently using. So we have to
3301 * be careful to only set the discarded attribute if we know it
3302 * covers a complete block of the new size.
3303 */
3304struct discard_load_info {
3305 struct cache *cache;
3306
3307 /*
3308 * These blocks are sized using the on disk dblock size, rather
3309 * than the current one.
3310 */
3311 dm_block_t block_size;
3312 dm_block_t discard_begin, discard_end;
3313};
3314
3315static void discard_load_info_init(struct cache *cache,
3316 struct discard_load_info *li)
3317{
3318 li->cache = cache;
3319 li->discard_begin = li->discard_end = 0;
3320}
3321
3322static void set_discard_range(struct discard_load_info *li)
3323{
3324 sector_t b, e;
3325
3326 if (li->discard_begin == li->discard_end)
3327 return;
3328
3329 /*
3330 * Convert to sectors.
3331 */
3332 b = li->discard_begin * li->block_size;
3333 e = li->discard_end * li->block_size;
3334
3335 /*
3336 * Then convert back to the current dblock size.
3337 */
3338 b = dm_sector_div_up(b, li->cache->discard_block_size);
3339 sector_div(e, li->cache->discard_block_size);
3340
3341 /*
3342 * The origin may have shrunk, so we need to check we're still in
3343 * bounds.
3344 */
3345 if (e > from_dblock(li->cache->discard_nr_blocks))
3346 e = from_dblock(li->cache->discard_nr_blocks);
3347
3348 for (; b < e; b++)
3349 set_discard(li->cache, to_dblock(b));
3350}
3351
3352static int load_discard(void *context, sector_t discard_block_size,
3353 dm_dblock_t dblock, bool discard)
3354{
3355 struct discard_load_info *li = context;
3356
3357 li->block_size = discard_block_size;
3358
3359 if (discard) {
3360 if (from_dblock(dblock) == li->discard_end)
3361 /*
3362 * We're already in a discard range, just extend it.
3363 */
3364 li->discard_end = li->discard_end + 1ULL;
3365
3366 else {
3367 /*
3368 * Emit the old range and start a new one.
3369 */
3370 set_discard_range(li);
3371 li->discard_begin = from_dblock(dblock);
3372 li->discard_end = li->discard_begin + 1ULL;
3373 }
3374 } else {
3375 set_discard_range(li);
3376 li->discard_begin = li->discard_end = 0;
3377 }
3378
3379 return 0;
3380}
3381
3382static dm_cblock_t get_cache_dev_size(struct cache *cache)
3383{
3384 sector_t size = get_dev_size(cache->cache_dev);
3385 (void) sector_div(size, cache->sectors_per_block);
3386 return to_cblock(size);
3387}
3388
3389static bool can_resize(struct cache *cache, dm_cblock_t new_size)
3390{
3391 if (from_cblock(new_size) > from_cblock(cache->cache_size))
3392 return true;
3393
3394 /*
3395 * We can't drop a dirty block when shrinking the cache.
3396 */
3397 while (from_cblock(new_size) < from_cblock(cache->cache_size)) {
3398 new_size = to_cblock(from_cblock(new_size) + 1);
3399 if (is_dirty(cache, new_size)) {
3400 DMERR("%s: unable to shrink cache; cache block %llu is dirty",
3401 cache_device_name(cache),
3402 (unsigned long long) from_cblock(new_size));
3403 return false;
3404 }
3405 }
3406
3407 return true;
3408}
3409
3410static int resize_cache_dev(struct cache *cache, dm_cblock_t new_size)
3411{
3412 int r;
3413
3414 r = dm_cache_resize(cache->cmd, new_size);
3415 if (r) {
3416 DMERR("%s: could not resize cache metadata", cache_device_name(cache));
3417 metadata_operation_failed(cache, "dm_cache_resize", r);
3418 return r;
3419 }
3420
3421 set_cache_size(cache, new_size);
3422
3423 return 0;
3424}
3425
3426static int cache_preresume(struct dm_target *ti)
3427{
3428 int r = 0;
3429 struct cache *cache = ti->private;
3430 dm_cblock_t csize = get_cache_dev_size(cache);
3431
3432 /*
3433 * Check to see if the cache has resized.
3434 */
3435 if (!cache->sized) {
3436 r = resize_cache_dev(cache, csize);
3437 if (r)
3438 return r;
3439
3440 cache->sized = true;
3441
3442 } else if (csize != cache->cache_size) {
3443 if (!can_resize(cache, csize))
3444 return -EINVAL;
3445
3446 r = resize_cache_dev(cache, csize);
3447 if (r)
3448 return r;
3449 }
3450
3451 if (!cache->loaded_mappings) {
3452 r = dm_cache_load_mappings(cache->cmd, cache->policy,
3453 load_mapping, cache);
3454 if (r) {
3455 DMERR("%s: could not load cache mappings", cache_device_name(cache));
3456 metadata_operation_failed(cache, "dm_cache_load_mappings", r);
3457 return r;
3458 }
3459
3460 cache->loaded_mappings = true;
3461 }
3462
3463 if (!cache->loaded_discards) {
3464 struct discard_load_info li;
3465
3466 /*
3467 * The discard bitset could have been resized, or the
3468 * discard block size changed. To be safe we start by
3469 * setting every dblock to not discarded.
3470 */
3471 clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks));
3472
3473 discard_load_info_init(cache, &li);
3474 r = dm_cache_load_discards(cache->cmd, load_discard, &li);
3475 if (r) {
3476 DMERR("%s: could not load origin discards", cache_device_name(cache));
3477 metadata_operation_failed(cache, "dm_cache_load_discards", r);
3478 return r;
3479 }
3480 set_discard_range(&li);
3481
3482 cache->loaded_discards = true;
3483 }
3484
3485 return r;
3486}
3487
3488static void cache_resume(struct dm_target *ti)
3489{
3490 struct cache *cache = ti->private;
3491
3492 cache->need_tick_bio = true;
3493 do_waker(&cache->waker.work);
3494}
3495
3496/*
3497 * Status format:
3498 *
3499 * <metadata block size> <#used metadata blocks>/<#total metadata blocks>
3500 * <cache block size> <#used cache blocks>/<#total cache blocks>
3501 * <#read hits> <#read misses> <#write hits> <#write misses>
3502 * <#demotions> <#promotions> <#dirty>
3503 * <#features> <features>*
3504 * <#core args> <core args>
3505 * <policy name> <#policy args> <policy args>* <cache metadata mode> <needs_check>
3506 */
3507static void cache_status(struct dm_target *ti, status_type_t type,
3508 unsigned status_flags, char *result, unsigned maxlen)
3509{
3510 int r = 0;
3511 unsigned i;
3512 ssize_t sz = 0;
3513 dm_block_t nr_free_blocks_metadata = 0;
3514 dm_block_t nr_blocks_metadata = 0;
3515 char buf[BDEVNAME_SIZE];
3516 struct cache *cache = ti->private;
3517 dm_cblock_t residency;
3518 bool needs_check;
3519
3520 switch (type) {
3521 case STATUSTYPE_INFO:
3522 if (get_cache_mode(cache) == CM_FAIL) {
3523 DMEMIT("Fail");
3524 break;
3525 }
3526
3527 /* Commit to ensure statistics aren't out-of-date */
3528 if (!(status_flags & DM_STATUS_NOFLUSH_FLAG) && !dm_suspended(ti))
3529 (void) commit(cache, false);
3530
3531 r = dm_cache_get_free_metadata_block_count(cache->cmd, &nr_free_blocks_metadata);
3532 if (r) {
3533 DMERR("%s: dm_cache_get_free_metadata_block_count returned %d",
3534 cache_device_name(cache), r);
3535 goto err;
3536 }
3537
3538 r = dm_cache_get_metadata_dev_size(cache->cmd, &nr_blocks_metadata);
3539 if (r) {
3540 DMERR("%s: dm_cache_get_metadata_dev_size returned %d",
3541 cache_device_name(cache), r);
3542 goto err;
3543 }
3544
3545 residency = policy_residency(cache->policy);
3546
3547 DMEMIT("%u %llu/%llu %u %llu/%llu %u %u %u %u %u %u %lu ",
3548 (unsigned)DM_CACHE_METADATA_BLOCK_SIZE,
3549 (unsigned long long)(nr_blocks_metadata - nr_free_blocks_metadata),
3550 (unsigned long long)nr_blocks_metadata,
3551 cache->sectors_per_block,
3552 (unsigned long long) from_cblock(residency),
3553 (unsigned long long) from_cblock(cache->cache_size),
3554 (unsigned) atomic_read(&cache->stats.read_hit),
3555 (unsigned) atomic_read(&cache->stats.read_miss),
3556 (unsigned) atomic_read(&cache->stats.write_hit),
3557 (unsigned) atomic_read(&cache->stats.write_miss),
3558 (unsigned) atomic_read(&cache->stats.demotion),
3559 (unsigned) atomic_read(&cache->stats.promotion),
3560 (unsigned long) atomic_read(&cache->nr_dirty));
3561
3562 if (writethrough_mode(&cache->features))
3563 DMEMIT("1 writethrough ");
3564
3565 else if (passthrough_mode(&cache->features))
3566 DMEMIT("1 passthrough ");
3567
3568 else if (writeback_mode(&cache->features))
3569 DMEMIT("1 writeback ");
3570
3571 else {
3572 DMERR("%s: internal error: unknown io mode: %d",
3573 cache_device_name(cache), (int) cache->features.io_mode);
3574 goto err;
3575 }
3576
3577 DMEMIT("2 migration_threshold %llu ", (unsigned long long) cache->migration_threshold);
3578
3579 DMEMIT("%s ", dm_cache_policy_get_name(cache->policy));
3580 if (sz < maxlen) {
3581 r = policy_emit_config_values(cache->policy, result, maxlen, &sz);
3582 if (r)
3583 DMERR("%s: policy_emit_config_values returned %d",
3584 cache_device_name(cache), r);
3585 }
3586
3587 if (get_cache_mode(cache) == CM_READ_ONLY)
3588 DMEMIT("ro ");
3589 else
3590 DMEMIT("rw ");
3591
3592 r = dm_cache_metadata_needs_check(cache->cmd, &needs_check);
3593
3594 if (r || needs_check)
3595 DMEMIT("needs_check ");
3596 else
3597 DMEMIT("- ");
3598
3599 break;
3600
3601 case STATUSTYPE_TABLE:
3602 format_dev_t(buf, cache->metadata_dev->bdev->bd_dev);
3603 DMEMIT("%s ", buf);
3604 format_dev_t(buf, cache->cache_dev->bdev->bd_dev);
3605 DMEMIT("%s ", buf);
3606 format_dev_t(buf, cache->origin_dev->bdev->bd_dev);
3607 DMEMIT("%s", buf);
3608
3609 for (i = 0; i < cache->nr_ctr_args - 1; i++)
3610 DMEMIT(" %s", cache->ctr_args[i]);
3611 if (cache->nr_ctr_args)
3612 DMEMIT(" %s", cache->ctr_args[cache->nr_ctr_args - 1]);
3613 }
3614
3615 return;
3616
3617err:
3618 DMEMIT("Error");
3619}
3620
3621/*
3622 * A cache block range can take two forms:
3623 *
3624 * i) A single cblock, eg. '3456'
3625 * ii) A begin and end cblock with dots between, eg. 123-234
3626 */
3627static int parse_cblock_range(struct cache *cache, const char *str,
3628 struct cblock_range *result)
3629{
3630 char dummy;
3631 uint64_t b, e;
3632 int r;
3633
3634 /*
3635 * Try and parse form (ii) first.
3636 */
3637 r = sscanf(str, "%llu-%llu%c", &b, &e, &dummy);
3638 if (r < 0)
3639 return r;
3640
3641 if (r == 2) {
3642 result->begin = to_cblock(b);
3643 result->end = to_cblock(e);
3644 return 0;
3645 }
3646
3647 /*
3648 * That didn't work, try form (i).
3649 */
3650 r = sscanf(str, "%llu%c", &b, &dummy);
3651 if (r < 0)
3652 return r;
3653
3654 if (r == 1) {
3655 result->begin = to_cblock(b);
3656 result->end = to_cblock(from_cblock(result->begin) + 1u);
3657 return 0;
3658 }
3659
3660 DMERR("%s: invalid cblock range '%s'", cache_device_name(cache), str);
3661 return -EINVAL;
3662}
3663
3664static int validate_cblock_range(struct cache *cache, struct cblock_range *range)
3665{
3666 uint64_t b = from_cblock(range->begin);
3667 uint64_t e = from_cblock(range->end);
3668 uint64_t n = from_cblock(cache->cache_size);
3669
3670 if (b >= n) {
3671 DMERR("%s: begin cblock out of range: %llu >= %llu",
3672 cache_device_name(cache), b, n);
3673 return -EINVAL;
3674 }
3675
3676 if (e > n) {
3677 DMERR("%s: end cblock out of range: %llu > %llu",
3678 cache_device_name(cache), e, n);
3679 return -EINVAL;
3680 }
3681
3682 if (b >= e) {
3683 DMERR("%s: invalid cblock range: %llu >= %llu",
3684 cache_device_name(cache), b, e);
3685 return -EINVAL;
3686 }
3687
3688 return 0;
3689}
3690
3691static int request_invalidation(struct cache *cache, struct cblock_range *range)
3692{
3693 struct invalidation_request req;
3694
3695 INIT_LIST_HEAD(&req.list);
3696 req.cblocks = range;
3697 atomic_set(&req.complete, 0);
3698 req.err = 0;
3699 init_waitqueue_head(&req.result_wait);
3700
3701 spin_lock(&cache->invalidation_lock);
3702 list_add(&req.list, &cache->invalidation_requests);
3703 spin_unlock(&cache->invalidation_lock);
3704 wake_worker(cache);
3705
3706 wait_event(req.result_wait, atomic_read(&req.complete));
3707 return req.err;
3708}
3709
3710static int process_invalidate_cblocks_message(struct cache *cache, unsigned count,
3711 const char **cblock_ranges)
3712{
3713 int r = 0;
3714 unsigned i;
3715 struct cblock_range range;
3716
3717 if (!passthrough_mode(&cache->features)) {
3718 DMERR("%s: cache has to be in passthrough mode for invalidation",
3719 cache_device_name(cache));
3720 return -EPERM;
3721 }
3722
3723 for (i = 0; i < count; i++) {
3724 r = parse_cblock_range(cache, cblock_ranges[i], &range);
3725 if (r)
3726 break;
3727
3728 r = validate_cblock_range(cache, &range);
3729 if (r)
3730 break;
3731
3732 /*
3733 * Pass begin and end origin blocks to the worker and wake it.
3734 */
3735 r = request_invalidation(cache, &range);
3736 if (r)
3737 break;
3738 }
3739
3740 return r;
3741}
3742
3743/*
3744 * Supports
3745 * "<key> <value>"
3746 * and
3747 * "invalidate_cblocks [(<begin>)|(<begin>-<end>)]*
3748 *
3749 * The key migration_threshold is supported by the cache target core.
3750 */
3751static int cache_message(struct dm_target *ti, unsigned argc, char **argv)
3752{
3753 struct cache *cache = ti->private;
3754
3755 if (!argc)
3756 return -EINVAL;
3757
3758 if (get_cache_mode(cache) >= CM_READ_ONLY) {
3759 DMERR("%s: unable to service cache target messages in READ_ONLY or FAIL mode",
3760 cache_device_name(cache));
3761 return -EOPNOTSUPP;
3762 }
3763
3764 if (!strcasecmp(argv[0], "invalidate_cblocks"))
3765 return process_invalidate_cblocks_message(cache, argc - 1, (const char **) argv + 1);
3766
3767 if (argc != 2)
3768 return -EINVAL;
3769
3770 return set_config_value(cache, argv[0], argv[1]);
3771}
3772
3773static int cache_iterate_devices(struct dm_target *ti,
3774 iterate_devices_callout_fn fn, void *data)
3775{
3776 int r = 0;
3777 struct cache *cache = ti->private;
3778
3779 r = fn(ti, cache->cache_dev, 0, get_dev_size(cache->cache_dev), data);
3780 if (!r)
3781 r = fn(ti, cache->origin_dev, 0, ti->len, data);
3782
3783 return r;
3784}
3785
3786static void set_discard_limits(struct cache *cache, struct queue_limits *limits)
3787{
3788 /*
3789 * FIXME: these limits may be incompatible with the cache device
3790 */
3791 limits->max_discard_sectors = min_t(sector_t, cache->discard_block_size * 1024,
3792 cache->origin_sectors);
3793 limits->discard_granularity = cache->discard_block_size << SECTOR_SHIFT;
3794}
3795
3796static void cache_io_hints(struct dm_target *ti, struct queue_limits *limits)
3797{
3798 struct cache *cache = ti->private;
3799 uint64_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;
3800
3801 /*
3802 * If the system-determined stacked limits are compatible with the
3803 * cache's blocksize (io_opt is a factor) do not override them.
3804 */
3805 if (io_opt_sectors < cache->sectors_per_block ||
3806 do_div(io_opt_sectors, cache->sectors_per_block)) {
3807 blk_limits_io_min(limits, cache->sectors_per_block << SECTOR_SHIFT);
3808 blk_limits_io_opt(limits, cache->sectors_per_block << SECTOR_SHIFT);
3809 }
3810 set_discard_limits(cache, limits);
3811}
3812
3813/*----------------------------------------------------------------*/
3814
3815static struct target_type cache_target = {
3816 .name = "cache",
3817 .version = {1, 9, 0},
3818 .module = THIS_MODULE,
3819 .ctr = cache_ctr,
3820 .dtr = cache_dtr,
3821 .map = cache_map,
3822 .end_io = cache_end_io,
3823 .postsuspend = cache_postsuspend,
3824 .preresume = cache_preresume,
3825 .resume = cache_resume,
3826 .status = cache_status,
3827 .message = cache_message,
3828 .iterate_devices = cache_iterate_devices,
3829 .io_hints = cache_io_hints,
3830};
3831
3832static int __init dm_cache_init(void)
3833{
3834 int r;
3835
3836 r = dm_register_target(&cache_target);
3837 if (r) {
3838 DMERR("cache target registration failed: %d", r);
3839 return r;
3840 }
3841
3842 migration_cache = KMEM_CACHE(dm_cache_migration, 0);
3843 if (!migration_cache) {
3844 dm_unregister_target(&cache_target);
3845 return -ENOMEM;
3846 }
3847
3848 return 0;
3849}
3850
3851static void __exit dm_cache_exit(void)
3852{
3853 dm_unregister_target(&cache_target);
3854 kmem_cache_destroy(migration_cache);
3855}
3856
3857module_init(dm_cache_init);
3858module_exit(dm_cache_exit);
3859
3860MODULE_DESCRIPTION(DM_NAME " cache target");
3861MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
3862MODULE_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");