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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/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");