2 * Copyright (C) 2011-2012 Red Hat UK.
4 * This file is released under the GPL.
7 #include "dm-thin-metadata.h"
8 #include "dm-bio-prison.h"
11 #include <linux/device-mapper.h>
12 #include <linux/dm-io.h>
13 #include <linux/dm-kcopyd.h>
14 #include <linux/list.h>
15 #include <linux/init.h>
16 #include <linux/module.h>
17 #include <linux/slab.h>
19 #define DM_MSG_PREFIX "thin"
24 #define ENDIO_HOOK_POOL_SIZE 1024
25 #define MAPPING_POOL_SIZE 1024
26 #define PRISON_CELLS 1024
27 #define COMMIT_PERIOD HZ
30 * The block size of the device holding pool data must be
31 * between 64KB and 1GB.
33 #define DATA_DEV_BLOCK_SIZE_MIN_SECTORS (64 * 1024 >> SECTOR_SHIFT)
34 #define DATA_DEV_BLOCK_SIZE_MAX_SECTORS (1024 * 1024 * 1024 >> SECTOR_SHIFT)
37 * Device id is restricted to 24 bits.
39 #define MAX_DEV_ID ((1 << 24) - 1)
42 * How do we handle breaking sharing of data blocks?
43 * =================================================
45 * We use a standard copy-on-write btree to store the mappings for the
46 * devices (note I'm talking about copy-on-write of the metadata here, not
47 * the data). When you take an internal snapshot you clone the root node
48 * of the origin btree. After this there is no concept of an origin or a
49 * snapshot. They are just two device trees that happen to point to the
52 * When we get a write in we decide if it's to a shared data block using
53 * some timestamp magic. If it is, we have to break sharing.
55 * Let's say we write to a shared block in what was the origin. The
58 * i) plug io further to this physical block. (see bio_prison code).
60 * ii) quiesce any read io to that shared data block. Obviously
61 * including all devices that share this block. (see dm_deferred_set code)
63 * iii) copy the data block to a newly allocate block. This step can be
64 * missed out if the io covers the block. (schedule_copy).
66 * iv) insert the new mapping into the origin's btree
67 * (process_prepared_mapping). This act of inserting breaks some
68 * sharing of btree nodes between the two devices. Breaking sharing only
69 * effects the btree of that specific device. Btrees for the other
70 * devices that share the block never change. The btree for the origin
71 * device as it was after the last commit is untouched, ie. we're using
72 * persistent data structures in the functional programming sense.
74 * v) unplug io to this physical block, including the io that triggered
75 * the breaking of sharing.
77 * Steps (ii) and (iii) occur in parallel.
79 * The metadata _doesn't_ need to be committed before the io continues. We
80 * get away with this because the io is always written to a _new_ block.
81 * If there's a crash, then:
83 * - The origin mapping will point to the old origin block (the shared
84 * one). This will contain the data as it was before the io that triggered
85 * the breaking of sharing came in.
87 * - The snap mapping still points to the old block. As it would after
90 * The downside of this scheme is the timestamp magic isn't perfect, and
91 * will continue to think that data block in the snapshot device is shared
92 * even after the write to the origin has broken sharing. I suspect data
93 * blocks will typically be shared by many different devices, so we're
94 * breaking sharing n + 1 times, rather than n, where n is the number of
95 * devices that reference this data block. At the moment I think the
96 * benefits far, far outweigh the disadvantages.
99 /*----------------------------------------------------------------*/
104 static void build_data_key(struct dm_thin_device *td,
105 dm_block_t b, struct dm_cell_key *key)
108 key->dev = dm_thin_dev_id(td);
112 static void build_virtual_key(struct dm_thin_device *td, dm_block_t b,
113 struct dm_cell_key *key)
116 key->dev = dm_thin_dev_id(td);
120 /*----------------------------------------------------------------*/
123 * A pool device ties together a metadata device and a data device. It
124 * also provides the interface for creating and destroying internal
127 struct dm_thin_new_mapping;
130 * The pool runs in 3 modes. Ordered in degraded order for comparisons.
133 PM_WRITE, /* metadata may be changed */
134 PM_READ_ONLY, /* metadata may not be changed */
135 PM_FAIL, /* all I/O fails */
138 struct pool_features {
141 bool zero_new_blocks:1;
142 bool discard_enabled:1;
143 bool discard_passdown:1;
147 typedef void (*process_bio_fn)(struct thin_c *tc, struct bio *bio);
148 typedef void (*process_mapping_fn)(struct dm_thin_new_mapping *m);
151 struct list_head list;
152 struct dm_target *ti; /* Only set if a pool target is bound */
154 struct mapped_device *pool_md;
155 struct block_device *md_dev;
156 struct dm_pool_metadata *pmd;
158 dm_block_t low_water_blocks;
159 uint32_t sectors_per_block;
160 int sectors_per_block_shift;
162 struct pool_features pf;
163 unsigned low_water_triggered:1; /* A dm event has been sent */
164 unsigned no_free_space:1; /* A -ENOSPC warning has been issued */
166 struct dm_bio_prison *prison;
167 struct dm_kcopyd_client *copier;
169 struct workqueue_struct *wq;
170 struct work_struct worker;
171 struct delayed_work waker;
173 unsigned long last_commit_jiffies;
177 struct bio_list deferred_bios;
178 struct bio_list deferred_flush_bios;
179 struct list_head prepared_mappings;
180 struct list_head prepared_discards;
182 struct bio_list retry_on_resume_list;
184 struct dm_deferred_set *shared_read_ds;
185 struct dm_deferred_set *all_io_ds;
187 struct dm_thin_new_mapping *next_mapping;
188 mempool_t *mapping_pool;
190 process_bio_fn process_bio;
191 process_bio_fn process_discard;
193 process_mapping_fn process_prepared_mapping;
194 process_mapping_fn process_prepared_discard;
197 static enum pool_mode get_pool_mode(struct pool *pool);
198 static void set_pool_mode(struct pool *pool, enum pool_mode mode);
201 * Target context for a pool.
204 struct dm_target *ti;
206 struct dm_dev *data_dev;
207 struct dm_dev *metadata_dev;
208 struct dm_target_callbacks callbacks;
210 dm_block_t low_water_blocks;
211 struct pool_features requested_pf; /* Features requested during table load */
212 struct pool_features adjusted_pf; /* Features used after adjusting for constituent devices */
216 * Target context for a thin.
219 struct dm_dev *pool_dev;
220 struct dm_dev *origin_dev;
224 struct dm_thin_device *td;
227 /*----------------------------------------------------------------*/
230 * A global list of pools that uses a struct mapped_device as a key.
232 static struct dm_thin_pool_table {
234 struct list_head pools;
235 } dm_thin_pool_table;
237 static void pool_table_init(void)
239 mutex_init(&dm_thin_pool_table.mutex);
240 INIT_LIST_HEAD(&dm_thin_pool_table.pools);
243 static void __pool_table_insert(struct pool *pool)
245 BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex));
246 list_add(&pool->list, &dm_thin_pool_table.pools);
249 static void __pool_table_remove(struct pool *pool)
251 BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex));
252 list_del(&pool->list);
255 static struct pool *__pool_table_lookup(struct mapped_device *md)
257 struct pool *pool = NULL, *tmp;
259 BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex));
261 list_for_each_entry(tmp, &dm_thin_pool_table.pools, list) {
262 if (tmp->pool_md == md) {
271 static struct pool *__pool_table_lookup_metadata_dev(struct block_device *md_dev)
273 struct pool *pool = NULL, *tmp;
275 BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex));
277 list_for_each_entry(tmp, &dm_thin_pool_table.pools, list) {
278 if (tmp->md_dev == md_dev) {
287 /*----------------------------------------------------------------*/
289 struct dm_thin_endio_hook {
291 struct dm_deferred_entry *shared_read_entry;
292 struct dm_deferred_entry *all_io_entry;
293 struct dm_thin_new_mapping *overwrite_mapping;
296 static void __requeue_bio_list(struct thin_c *tc, struct bio_list *master)
299 struct bio_list bios;
301 bio_list_init(&bios);
302 bio_list_merge(&bios, master);
303 bio_list_init(master);
305 while ((bio = bio_list_pop(&bios))) {
306 struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
309 bio_endio(bio, DM_ENDIO_REQUEUE);
311 bio_list_add(master, bio);
315 static void requeue_io(struct thin_c *tc)
317 struct pool *pool = tc->pool;
320 spin_lock_irqsave(&pool->lock, flags);
321 __requeue_bio_list(tc, &pool->deferred_bios);
322 __requeue_bio_list(tc, &pool->retry_on_resume_list);
323 spin_unlock_irqrestore(&pool->lock, flags);
327 * This section of code contains the logic for processing a thin device's IO.
328 * Much of the code depends on pool object resources (lists, workqueues, etc)
329 * but most is exclusively called from the thin target rather than the thin-pool
333 static dm_block_t get_bio_block(struct thin_c *tc, struct bio *bio)
335 sector_t block_nr = bio->bi_sector;
337 if (tc->pool->sectors_per_block_shift < 0)
338 (void) sector_div(block_nr, tc->pool->sectors_per_block);
340 block_nr >>= tc->pool->sectors_per_block_shift;
345 static void remap(struct thin_c *tc, struct bio *bio, dm_block_t block)
347 struct pool *pool = tc->pool;
348 sector_t bi_sector = bio->bi_sector;
350 bio->bi_bdev = tc->pool_dev->bdev;
351 if (tc->pool->sectors_per_block_shift < 0)
352 bio->bi_sector = (block * pool->sectors_per_block) +
353 sector_div(bi_sector, pool->sectors_per_block);
355 bio->bi_sector = (block << pool->sectors_per_block_shift) |
356 (bi_sector & (pool->sectors_per_block - 1));
359 static void remap_to_origin(struct thin_c *tc, struct bio *bio)
361 bio->bi_bdev = tc->origin_dev->bdev;
364 static int bio_triggers_commit(struct thin_c *tc, struct bio *bio)
366 return (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) &&
367 dm_thin_changed_this_transaction(tc->td);
370 static void inc_all_io_entry(struct pool *pool, struct bio *bio)
372 struct dm_thin_endio_hook *h;
374 if (bio->bi_rw & REQ_DISCARD)
377 h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
378 h->all_io_entry = dm_deferred_entry_inc(pool->all_io_ds);
381 static void issue(struct thin_c *tc, struct bio *bio)
383 struct pool *pool = tc->pool;
386 if (!bio_triggers_commit(tc, bio)) {
387 generic_make_request(bio);
392 * Complete bio with an error if earlier I/O caused changes to
393 * the metadata that can't be committed e.g, due to I/O errors
394 * on the metadata device.
396 if (dm_thin_aborted_changes(tc->td)) {
402 * Batch together any bios that trigger commits and then issue a
403 * single commit for them in process_deferred_bios().
405 spin_lock_irqsave(&pool->lock, flags);
406 bio_list_add(&pool->deferred_flush_bios, bio);
407 spin_unlock_irqrestore(&pool->lock, flags);
410 static void remap_to_origin_and_issue(struct thin_c *tc, struct bio *bio)
412 remap_to_origin(tc, bio);
416 static void remap_and_issue(struct thin_c *tc, struct bio *bio,
419 remap(tc, bio, block);
424 * wake_worker() is used when new work is queued and when pool_resume is
425 * ready to continue deferred IO processing.
427 static void wake_worker(struct pool *pool)
429 queue_work(pool->wq, &pool->worker);
432 /*----------------------------------------------------------------*/
435 * Bio endio functions.
437 struct dm_thin_new_mapping {
438 struct list_head list;
442 unsigned pass_discard:1;
445 dm_block_t virt_block;
446 dm_block_t data_block;
447 struct dm_bio_prison_cell *cell, *cell2;
451 * If the bio covers the whole area of a block then we can avoid
452 * zeroing or copying. Instead this bio is hooked. The bio will
453 * still be in the cell, so care has to be taken to avoid issuing
457 bio_end_io_t *saved_bi_end_io;
460 static void __maybe_add_mapping(struct dm_thin_new_mapping *m)
462 struct pool *pool = m->tc->pool;
464 if (m->quiesced && m->prepared) {
465 list_add(&m->list, &pool->prepared_mappings);
470 static void copy_complete(int read_err, unsigned long write_err, void *context)
473 struct dm_thin_new_mapping *m = context;
474 struct pool *pool = m->tc->pool;
476 m->err = read_err || write_err ? -EIO : 0;
478 spin_lock_irqsave(&pool->lock, flags);
480 __maybe_add_mapping(m);
481 spin_unlock_irqrestore(&pool->lock, flags);
484 static void overwrite_endio(struct bio *bio, int err)
487 struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
488 struct dm_thin_new_mapping *m = h->overwrite_mapping;
489 struct pool *pool = m->tc->pool;
493 spin_lock_irqsave(&pool->lock, flags);
495 __maybe_add_mapping(m);
496 spin_unlock_irqrestore(&pool->lock, flags);
499 /*----------------------------------------------------------------*/
506 * Prepared mapping jobs.
510 * This sends the bios in the cell back to the deferred_bios list.
512 static void cell_defer(struct thin_c *tc, struct dm_bio_prison_cell *cell)
514 struct pool *pool = tc->pool;
517 spin_lock_irqsave(&pool->lock, flags);
518 dm_cell_release(cell, &pool->deferred_bios);
519 spin_unlock_irqrestore(&tc->pool->lock, flags);
525 * Same as cell_defer except it omits the original holder of the cell.
527 static void cell_defer_no_holder(struct thin_c *tc, struct dm_bio_prison_cell *cell)
529 struct pool *pool = tc->pool;
532 spin_lock_irqsave(&pool->lock, flags);
533 dm_cell_release_no_holder(cell, &pool->deferred_bios);
534 spin_unlock_irqrestore(&pool->lock, flags);
539 static void process_prepared_mapping_fail(struct dm_thin_new_mapping *m)
542 m->bio->bi_end_io = m->saved_bi_end_io;
543 dm_cell_error(m->cell);
545 mempool_free(m, m->tc->pool->mapping_pool);
547 static void process_prepared_mapping(struct dm_thin_new_mapping *m)
549 struct thin_c *tc = m->tc;
555 bio->bi_end_io = m->saved_bi_end_io;
558 dm_cell_error(m->cell);
563 * Commit the prepared block into the mapping btree.
564 * Any I/O for this block arriving after this point will get
565 * remapped to it directly.
567 r = dm_thin_insert_block(tc->td, m->virt_block, m->data_block);
569 DMERR_LIMIT("dm_thin_insert_block() failed");
570 dm_cell_error(m->cell);
575 * Release any bios held while the block was being provisioned.
576 * If we are processing a write bio that completely covers the block,
577 * we already processed it so can ignore it now when processing
578 * the bios in the cell.
581 cell_defer_no_holder(tc, m->cell);
584 cell_defer(tc, m->cell);
588 mempool_free(m, tc->pool->mapping_pool);
591 static void process_prepared_discard_fail(struct dm_thin_new_mapping *m)
593 struct thin_c *tc = m->tc;
595 bio_io_error(m->bio);
596 cell_defer_no_holder(tc, m->cell);
597 cell_defer_no_holder(tc, m->cell2);
598 mempool_free(m, tc->pool->mapping_pool);
601 static void process_prepared_discard_passdown(struct dm_thin_new_mapping *m)
603 struct thin_c *tc = m->tc;
605 inc_all_io_entry(tc->pool, m->bio);
606 cell_defer_no_holder(tc, m->cell);
607 cell_defer_no_holder(tc, m->cell2);
610 remap_and_issue(tc, m->bio, m->data_block);
612 bio_endio(m->bio, 0);
614 mempool_free(m, tc->pool->mapping_pool);
617 static void process_prepared_discard(struct dm_thin_new_mapping *m)
620 struct thin_c *tc = m->tc;
622 r = dm_thin_remove_block(tc->td, m->virt_block);
624 DMERR_LIMIT("dm_thin_remove_block() failed");
626 process_prepared_discard_passdown(m);
629 static void process_prepared(struct pool *pool, struct list_head *head,
630 process_mapping_fn *fn)
633 struct list_head maps;
634 struct dm_thin_new_mapping *m, *tmp;
636 INIT_LIST_HEAD(&maps);
637 spin_lock_irqsave(&pool->lock, flags);
638 list_splice_init(head, &maps);
639 spin_unlock_irqrestore(&pool->lock, flags);
641 list_for_each_entry_safe(m, tmp, &maps, list)
648 static int io_overlaps_block(struct pool *pool, struct bio *bio)
650 return bio->bi_size == (pool->sectors_per_block << SECTOR_SHIFT);
653 static int io_overwrites_block(struct pool *pool, struct bio *bio)
655 return (bio_data_dir(bio) == WRITE) &&
656 io_overlaps_block(pool, bio);
659 static void save_and_set_endio(struct bio *bio, bio_end_io_t **save,
662 *save = bio->bi_end_io;
666 static int ensure_next_mapping(struct pool *pool)
668 if (pool->next_mapping)
671 pool->next_mapping = mempool_alloc(pool->mapping_pool, GFP_ATOMIC);
673 return pool->next_mapping ? 0 : -ENOMEM;
676 static struct dm_thin_new_mapping *get_next_mapping(struct pool *pool)
678 struct dm_thin_new_mapping *r = pool->next_mapping;
680 BUG_ON(!pool->next_mapping);
682 pool->next_mapping = NULL;
687 static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,
688 struct dm_dev *origin, dm_block_t data_origin,
689 dm_block_t data_dest,
690 struct dm_bio_prison_cell *cell, struct bio *bio)
693 struct pool *pool = tc->pool;
694 struct dm_thin_new_mapping *m = get_next_mapping(pool);
696 INIT_LIST_HEAD(&m->list);
700 m->virt_block = virt_block;
701 m->data_block = data_dest;
706 if (!dm_deferred_set_add_work(pool->shared_read_ds, &m->list))
710 * IO to pool_dev remaps to the pool target's data_dev.
712 * If the whole block of data is being overwritten, we can issue the
713 * bio immediately. Otherwise we use kcopyd to clone the data first.
715 if (io_overwrites_block(pool, bio)) {
716 struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
718 h->overwrite_mapping = m;
720 save_and_set_endio(bio, &m->saved_bi_end_io, overwrite_endio);
721 inc_all_io_entry(pool, bio);
722 remap_and_issue(tc, bio, data_dest);
724 struct dm_io_region from, to;
726 from.bdev = origin->bdev;
727 from.sector = data_origin * pool->sectors_per_block;
728 from.count = pool->sectors_per_block;
730 to.bdev = tc->pool_dev->bdev;
731 to.sector = data_dest * pool->sectors_per_block;
732 to.count = pool->sectors_per_block;
734 r = dm_kcopyd_copy(pool->copier, &from, 1, &to,
735 0, copy_complete, m);
737 mempool_free(m, pool->mapping_pool);
738 DMERR_LIMIT("dm_kcopyd_copy() failed");
744 static void schedule_internal_copy(struct thin_c *tc, dm_block_t virt_block,
745 dm_block_t data_origin, dm_block_t data_dest,
746 struct dm_bio_prison_cell *cell, struct bio *bio)
748 schedule_copy(tc, virt_block, tc->pool_dev,
749 data_origin, data_dest, cell, bio);
752 static void schedule_external_copy(struct thin_c *tc, dm_block_t virt_block,
753 dm_block_t data_dest,
754 struct dm_bio_prison_cell *cell, struct bio *bio)
756 schedule_copy(tc, virt_block, tc->origin_dev,
757 virt_block, data_dest, cell, bio);
760 static void schedule_zero(struct thin_c *tc, dm_block_t virt_block,
761 dm_block_t data_block, struct dm_bio_prison_cell *cell,
764 struct pool *pool = tc->pool;
765 struct dm_thin_new_mapping *m = get_next_mapping(pool);
767 INIT_LIST_HEAD(&m->list);
771 m->virt_block = virt_block;
772 m->data_block = data_block;
778 * If the whole block of data is being overwritten or we are not
779 * zeroing pre-existing data, we can issue the bio immediately.
780 * Otherwise we use kcopyd to zero the data first.
782 if (!pool->pf.zero_new_blocks)
783 process_prepared_mapping(m);
785 else if (io_overwrites_block(pool, bio)) {
786 struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
788 h->overwrite_mapping = m;
790 save_and_set_endio(bio, &m->saved_bi_end_io, overwrite_endio);
791 inc_all_io_entry(pool, bio);
792 remap_and_issue(tc, bio, data_block);
795 struct dm_io_region to;
797 to.bdev = tc->pool_dev->bdev;
798 to.sector = data_block * pool->sectors_per_block;
799 to.count = pool->sectors_per_block;
801 r = dm_kcopyd_zero(pool->copier, 1, &to, 0, copy_complete, m);
803 mempool_free(m, pool->mapping_pool);
804 DMERR_LIMIT("dm_kcopyd_zero() failed");
810 static int commit(struct pool *pool)
814 r = dm_pool_commit_metadata(pool->pmd);
816 DMERR_LIMIT("commit failed: error = %d", r);
822 * A non-zero return indicates read_only or fail_io mode.
823 * Many callers don't care about the return value.
825 static int commit_or_fallback(struct pool *pool)
829 if (get_pool_mode(pool) != PM_WRITE)
834 set_pool_mode(pool, PM_READ_ONLY);
839 static int alloc_data_block(struct thin_c *tc, dm_block_t *result)
842 dm_block_t free_blocks;
844 struct pool *pool = tc->pool;
846 r = dm_pool_get_free_block_count(pool->pmd, &free_blocks);
850 if (free_blocks <= pool->low_water_blocks && !pool->low_water_triggered) {
851 DMWARN("%s: reached low water mark, sending event.",
852 dm_device_name(pool->pool_md));
853 spin_lock_irqsave(&pool->lock, flags);
854 pool->low_water_triggered = 1;
855 spin_unlock_irqrestore(&pool->lock, flags);
856 dm_table_event(pool->ti->table);
860 if (pool->no_free_space)
864 * Try to commit to see if that will free up some
867 (void) commit_or_fallback(pool);
869 r = dm_pool_get_free_block_count(pool->pmd, &free_blocks);
874 * If we still have no space we set a flag to avoid
875 * doing all this checking and return -ENOSPC.
878 DMWARN("%s: no free space available.",
879 dm_device_name(pool->pool_md));
880 spin_lock_irqsave(&pool->lock, flags);
881 pool->no_free_space = 1;
882 spin_unlock_irqrestore(&pool->lock, flags);
888 r = dm_pool_alloc_data_block(pool->pmd, result);
896 * If we have run out of space, queue bios until the device is
897 * resumed, presumably after having been reloaded with more space.
899 static void retry_on_resume(struct bio *bio)
901 struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
902 struct thin_c *tc = h->tc;
903 struct pool *pool = tc->pool;
906 spin_lock_irqsave(&pool->lock, flags);
907 bio_list_add(&pool->retry_on_resume_list, bio);
908 spin_unlock_irqrestore(&pool->lock, flags);
911 static void no_space(struct dm_bio_prison_cell *cell)
914 struct bio_list bios;
916 bio_list_init(&bios);
917 dm_cell_release(cell, &bios);
919 while ((bio = bio_list_pop(&bios)))
920 retry_on_resume(bio);
923 static void process_discard(struct thin_c *tc, struct bio *bio)
927 struct pool *pool = tc->pool;
928 struct dm_bio_prison_cell *cell, *cell2;
929 struct dm_cell_key key, key2;
930 dm_block_t block = get_bio_block(tc, bio);
931 struct dm_thin_lookup_result lookup_result;
932 struct dm_thin_new_mapping *m;
934 build_virtual_key(tc->td, block, &key);
935 if (dm_bio_detain(tc->pool->prison, &key, bio, &cell))
938 r = dm_thin_find_block(tc->td, block, 1, &lookup_result);
942 * Check nobody is fiddling with this pool block. This can
943 * happen if someone's in the process of breaking sharing
946 build_data_key(tc->td, lookup_result.block, &key2);
947 if (dm_bio_detain(tc->pool->prison, &key2, bio, &cell2)) {
948 cell_defer_no_holder(tc, cell);
952 if (io_overlaps_block(pool, bio)) {
954 * IO may still be going to the destination block. We must
955 * quiesce before we can do the removal.
957 m = get_next_mapping(pool);
959 m->pass_discard = (!lookup_result.shared) && pool->pf.discard_passdown;
960 m->virt_block = block;
961 m->data_block = lookup_result.block;
967 if (!dm_deferred_set_add_work(pool->all_io_ds, &m->list)) {
968 spin_lock_irqsave(&pool->lock, flags);
969 list_add(&m->list, &pool->prepared_discards);
970 spin_unlock_irqrestore(&pool->lock, flags);
974 inc_all_io_entry(pool, bio);
975 cell_defer_no_holder(tc, cell);
976 cell_defer_no_holder(tc, cell2);
979 * The DM core makes sure that the discard doesn't span
980 * a block boundary. So we submit the discard of a
981 * partial block appropriately.
983 if ((!lookup_result.shared) && pool->pf.discard_passdown)
984 remap_and_issue(tc, bio, lookup_result.block);
992 * It isn't provisioned, just forget it.
994 cell_defer_no_holder(tc, cell);
999 DMERR_LIMIT("%s: dm_thin_find_block() failed: error = %d",
1001 cell_defer_no_holder(tc, cell);
1007 static void break_sharing(struct thin_c *tc, struct bio *bio, dm_block_t block,
1008 struct dm_cell_key *key,
1009 struct dm_thin_lookup_result *lookup_result,
1010 struct dm_bio_prison_cell *cell)
1013 dm_block_t data_block;
1015 r = alloc_data_block(tc, &data_block);
1018 schedule_internal_copy(tc, block, lookup_result->block,
1019 data_block, cell, bio);
1027 DMERR_LIMIT("%s: alloc_data_block() failed: error = %d",
1029 dm_cell_error(cell);
1034 static void process_shared_bio(struct thin_c *tc, struct bio *bio,
1036 struct dm_thin_lookup_result *lookup_result)
1038 struct dm_bio_prison_cell *cell;
1039 struct pool *pool = tc->pool;
1040 struct dm_cell_key key;
1043 * If cell is already occupied, then sharing is already in the process
1044 * of being broken so we have nothing further to do here.
1046 build_data_key(tc->td, lookup_result->block, &key);
1047 if (dm_bio_detain(pool->prison, &key, bio, &cell))
1050 if (bio_data_dir(bio) == WRITE && bio->bi_size)
1051 break_sharing(tc, bio, block, &key, lookup_result, cell);
1053 struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
1055 h->shared_read_entry = dm_deferred_entry_inc(pool->shared_read_ds);
1056 inc_all_io_entry(pool, bio);
1057 cell_defer_no_holder(tc, cell);
1059 remap_and_issue(tc, bio, lookup_result->block);
1063 static void provision_block(struct thin_c *tc, struct bio *bio, dm_block_t block,
1064 struct dm_bio_prison_cell *cell)
1067 dm_block_t data_block;
1070 * Remap empty bios (flushes) immediately, without provisioning.
1072 if (!bio->bi_size) {
1073 inc_all_io_entry(tc->pool, bio);
1074 cell_defer_no_holder(tc, cell);
1076 remap_and_issue(tc, bio, 0);
1081 * Fill read bios with zeroes and complete them immediately.
1083 if (bio_data_dir(bio) == READ) {
1085 cell_defer_no_holder(tc, cell);
1090 r = alloc_data_block(tc, &data_block);
1094 schedule_external_copy(tc, block, data_block, cell, bio);
1096 schedule_zero(tc, block, data_block, cell, bio);
1104 DMERR_LIMIT("%s: alloc_data_block() failed: error = %d",
1106 set_pool_mode(tc->pool, PM_READ_ONLY);
1107 dm_cell_error(cell);
1112 static void process_bio(struct thin_c *tc, struct bio *bio)
1115 dm_block_t block = get_bio_block(tc, bio);
1116 struct dm_bio_prison_cell *cell;
1117 struct dm_cell_key key;
1118 struct dm_thin_lookup_result lookup_result;
1121 * If cell is already occupied, then the block is already
1122 * being provisioned so we have nothing further to do here.
1124 build_virtual_key(tc->td, block, &key);
1125 if (dm_bio_detain(tc->pool->prison, &key, bio, &cell))
1128 r = dm_thin_find_block(tc->td, block, 1, &lookup_result);
1131 if (lookup_result.shared) {
1132 process_shared_bio(tc, bio, block, &lookup_result);
1133 cell_defer_no_holder(tc, cell);
1135 inc_all_io_entry(tc->pool, bio);
1136 cell_defer_no_holder(tc, cell);
1138 remap_and_issue(tc, bio, lookup_result.block);
1143 if (bio_data_dir(bio) == READ && tc->origin_dev) {
1144 inc_all_io_entry(tc->pool, bio);
1145 cell_defer_no_holder(tc, cell);
1147 remap_to_origin_and_issue(tc, bio);
1149 provision_block(tc, bio, block, cell);
1153 DMERR_LIMIT("%s: dm_thin_find_block() failed: error = %d",
1155 cell_defer_no_holder(tc, cell);
1161 static void process_bio_read_only(struct thin_c *tc, struct bio *bio)
1164 int rw = bio_data_dir(bio);
1165 dm_block_t block = get_bio_block(tc, bio);
1166 struct dm_thin_lookup_result lookup_result;
1168 r = dm_thin_find_block(tc->td, block, 1, &lookup_result);
1171 if (lookup_result.shared && (rw == WRITE) && bio->bi_size)
1174 inc_all_io_entry(tc->pool, bio);
1175 remap_and_issue(tc, bio, lookup_result.block);
1185 if (tc->origin_dev) {
1186 inc_all_io_entry(tc->pool, bio);
1187 remap_to_origin_and_issue(tc, bio);
1196 DMERR_LIMIT("%s: dm_thin_find_block() failed: error = %d",
1203 static void process_bio_fail(struct thin_c *tc, struct bio *bio)
1208 static int need_commit_due_to_time(struct pool *pool)
1210 return jiffies < pool->last_commit_jiffies ||
1211 jiffies > pool->last_commit_jiffies + COMMIT_PERIOD;
1214 static void process_deferred_bios(struct pool *pool)
1216 unsigned long flags;
1218 struct bio_list bios;
1220 bio_list_init(&bios);
1222 spin_lock_irqsave(&pool->lock, flags);
1223 bio_list_merge(&bios, &pool->deferred_bios);
1224 bio_list_init(&pool->deferred_bios);
1225 spin_unlock_irqrestore(&pool->lock, flags);
1227 while ((bio = bio_list_pop(&bios))) {
1228 struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
1229 struct thin_c *tc = h->tc;
1232 * If we've got no free new_mapping structs, and processing
1233 * this bio might require one, we pause until there are some
1234 * prepared mappings to process.
1236 if (ensure_next_mapping(pool)) {
1237 spin_lock_irqsave(&pool->lock, flags);
1238 bio_list_merge(&pool->deferred_bios, &bios);
1239 spin_unlock_irqrestore(&pool->lock, flags);
1244 if (bio->bi_rw & REQ_DISCARD)
1245 pool->process_discard(tc, bio);
1247 pool->process_bio(tc, bio);
1251 * If there are any deferred flush bios, we must commit
1252 * the metadata before issuing them.
1254 bio_list_init(&bios);
1255 spin_lock_irqsave(&pool->lock, flags);
1256 bio_list_merge(&bios, &pool->deferred_flush_bios);
1257 bio_list_init(&pool->deferred_flush_bios);
1258 spin_unlock_irqrestore(&pool->lock, flags);
1260 if (bio_list_empty(&bios) && !need_commit_due_to_time(pool))
1263 if (commit_or_fallback(pool)) {
1264 while ((bio = bio_list_pop(&bios)))
1268 pool->last_commit_jiffies = jiffies;
1270 while ((bio = bio_list_pop(&bios)))
1271 generic_make_request(bio);
1274 static void do_worker(struct work_struct *ws)
1276 struct pool *pool = container_of(ws, struct pool, worker);
1278 process_prepared(pool, &pool->prepared_mappings, &pool->process_prepared_mapping);
1279 process_prepared(pool, &pool->prepared_discards, &pool->process_prepared_discard);
1280 process_deferred_bios(pool);
1284 * We want to commit periodically so that not too much
1285 * unwritten data builds up.
1287 static void do_waker(struct work_struct *ws)
1289 struct pool *pool = container_of(to_delayed_work(ws), struct pool, waker);
1291 queue_delayed_work(pool->wq, &pool->waker, COMMIT_PERIOD);
1294 /*----------------------------------------------------------------*/
1296 static enum pool_mode get_pool_mode(struct pool *pool)
1298 return pool->pf.mode;
1301 static void set_pool_mode(struct pool *pool, enum pool_mode mode)
1305 pool->pf.mode = mode;
1309 DMERR("switching pool to failure mode");
1310 pool->process_bio = process_bio_fail;
1311 pool->process_discard = process_bio_fail;
1312 pool->process_prepared_mapping = process_prepared_mapping_fail;
1313 pool->process_prepared_discard = process_prepared_discard_fail;
1317 DMERR("switching pool to read-only mode");
1318 r = dm_pool_abort_metadata(pool->pmd);
1320 DMERR("aborting transaction failed");
1321 set_pool_mode(pool, PM_FAIL);
1323 dm_pool_metadata_read_only(pool->pmd);
1324 pool->process_bio = process_bio_read_only;
1325 pool->process_discard = process_discard;
1326 pool->process_prepared_mapping = process_prepared_mapping_fail;
1327 pool->process_prepared_discard = process_prepared_discard_passdown;
1332 pool->process_bio = process_bio;
1333 pool->process_discard = process_discard;
1334 pool->process_prepared_mapping = process_prepared_mapping;
1335 pool->process_prepared_discard = process_prepared_discard;
1340 /*----------------------------------------------------------------*/
1343 * Mapping functions.
1347 * Called only while mapping a thin bio to hand it over to the workqueue.
1349 static void thin_defer_bio(struct thin_c *tc, struct bio *bio)
1351 unsigned long flags;
1352 struct pool *pool = tc->pool;
1354 spin_lock_irqsave(&pool->lock, flags);
1355 bio_list_add(&pool->deferred_bios, bio);
1356 spin_unlock_irqrestore(&pool->lock, flags);
1361 static void thin_hook_bio(struct thin_c *tc, struct bio *bio)
1363 struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
1366 h->shared_read_entry = NULL;
1367 h->all_io_entry = NULL;
1368 h->overwrite_mapping = NULL;
1372 * Non-blocking function called from the thin target's map function.
1374 static int thin_bio_map(struct dm_target *ti, struct bio *bio,
1375 union map_info *map_context)
1378 struct thin_c *tc = ti->private;
1379 dm_block_t block = get_bio_block(tc, bio);
1380 struct dm_thin_device *td = tc->td;
1381 struct dm_thin_lookup_result result;
1382 struct dm_bio_prison_cell *cell1, *cell2;
1383 struct dm_cell_key key;
1385 thin_hook_bio(tc, bio);
1387 if (get_pool_mode(tc->pool) == PM_FAIL) {
1389 return DM_MAPIO_SUBMITTED;
1392 if (bio->bi_rw & (REQ_DISCARD | REQ_FLUSH | REQ_FUA)) {
1393 thin_defer_bio(tc, bio);
1394 return DM_MAPIO_SUBMITTED;
1397 r = dm_thin_find_block(td, block, 0, &result);
1400 * Note that we defer readahead too.
1404 if (unlikely(result.shared)) {
1406 * We have a race condition here between the
1407 * result.shared value returned by the lookup and
1408 * snapshot creation, which may cause new
1411 * To avoid this always quiesce the origin before
1412 * taking the snap. You want to do this anyway to
1413 * ensure a consistent application view
1416 * More distant ancestors are irrelevant. The
1417 * shared flag will be set in their case.
1419 thin_defer_bio(tc, bio);
1420 return DM_MAPIO_SUBMITTED;
1423 build_virtual_key(tc->td, block, &key);
1424 if (dm_bio_detain(tc->pool->prison, &key, bio, &cell1))
1425 return DM_MAPIO_SUBMITTED;
1427 build_data_key(tc->td, result.block, &key);
1428 if (dm_bio_detain(tc->pool->prison, &key, bio, &cell2)) {
1429 cell_defer_no_holder(tc, cell1);
1430 return DM_MAPIO_SUBMITTED;
1433 inc_all_io_entry(tc->pool, bio);
1434 cell_defer_no_holder(tc, cell2);
1435 cell_defer_no_holder(tc, cell1);
1437 remap(tc, bio, result.block);
1438 return DM_MAPIO_REMAPPED;
1441 if (get_pool_mode(tc->pool) == PM_READ_ONLY) {
1443 * This block isn't provisioned, and we have no way
1444 * of doing so. Just error it.
1447 return DM_MAPIO_SUBMITTED;
1453 * In future, the failed dm_thin_find_block above could
1454 * provide the hint to load the metadata into cache.
1456 thin_defer_bio(tc, bio);
1457 return DM_MAPIO_SUBMITTED;
1461 * Must always call bio_io_error on failure.
1462 * dm_thin_find_block can fail with -EINVAL if the
1463 * pool is switched to fail-io mode.
1466 return DM_MAPIO_SUBMITTED;
1470 static int pool_is_congested(struct dm_target_callbacks *cb, int bdi_bits)
1473 unsigned long flags;
1474 struct pool_c *pt = container_of(cb, struct pool_c, callbacks);
1476 spin_lock_irqsave(&pt->pool->lock, flags);
1477 r = !bio_list_empty(&pt->pool->retry_on_resume_list);
1478 spin_unlock_irqrestore(&pt->pool->lock, flags);
1481 struct request_queue *q = bdev_get_queue(pt->data_dev->bdev);
1482 r = bdi_congested(&q->backing_dev_info, bdi_bits);
1488 static void __requeue_bios(struct pool *pool)
1490 bio_list_merge(&pool->deferred_bios, &pool->retry_on_resume_list);
1491 bio_list_init(&pool->retry_on_resume_list);
1494 /*----------------------------------------------------------------
1495 * Binding of control targets to a pool object
1496 *--------------------------------------------------------------*/
1497 static bool data_dev_supports_discard(struct pool_c *pt)
1499 struct request_queue *q = bdev_get_queue(pt->data_dev->bdev);
1501 return q && blk_queue_discard(q);
1505 * If discard_passdown was enabled verify that the data device
1506 * supports discards. Disable discard_passdown if not.
1508 static void disable_passdown_if_not_supported(struct pool_c *pt)
1510 struct pool *pool = pt->pool;
1511 struct block_device *data_bdev = pt->data_dev->bdev;
1512 struct queue_limits *data_limits = &bdev_get_queue(data_bdev)->limits;
1513 sector_t block_size = pool->sectors_per_block << SECTOR_SHIFT;
1514 const char *reason = NULL;
1515 char buf[BDEVNAME_SIZE];
1517 if (!pt->adjusted_pf.discard_passdown)
1520 if (!data_dev_supports_discard(pt))
1521 reason = "discard unsupported";
1523 else if (data_limits->max_discard_sectors < pool->sectors_per_block)
1524 reason = "max discard sectors smaller than a block";
1526 else if (data_limits->discard_granularity > block_size)
1527 reason = "discard granularity larger than a block";
1529 else if (block_size & (data_limits->discard_granularity - 1))
1530 reason = "discard granularity not a factor of block size";
1533 DMWARN("Data device (%s) %s: Disabling discard passdown.", bdevname(data_bdev, buf), reason);
1534 pt->adjusted_pf.discard_passdown = false;
1538 static int bind_control_target(struct pool *pool, struct dm_target *ti)
1540 struct pool_c *pt = ti->private;
1543 * We want to make sure that degraded pools are never upgraded.
1545 enum pool_mode old_mode = pool->pf.mode;
1546 enum pool_mode new_mode = pt->adjusted_pf.mode;
1548 if (old_mode > new_mode)
1549 new_mode = old_mode;
1552 pool->low_water_blocks = pt->low_water_blocks;
1553 pool->pf = pt->adjusted_pf;
1555 set_pool_mode(pool, new_mode);
1560 static void unbind_control_target(struct pool *pool, struct dm_target *ti)
1566 /*----------------------------------------------------------------
1568 *--------------------------------------------------------------*/
1569 /* Initialize pool features. */
1570 static void pool_features_init(struct pool_features *pf)
1572 pf->mode = PM_WRITE;
1573 pf->zero_new_blocks = true;
1574 pf->discard_enabled = true;
1575 pf->discard_passdown = true;
1578 static void __pool_destroy(struct pool *pool)
1580 __pool_table_remove(pool);
1582 if (dm_pool_metadata_close(pool->pmd) < 0)
1583 DMWARN("%s: dm_pool_metadata_close() failed.", __func__);
1585 dm_bio_prison_destroy(pool->prison);
1586 dm_kcopyd_client_destroy(pool->copier);
1589 destroy_workqueue(pool->wq);
1591 if (pool->next_mapping)
1592 mempool_free(pool->next_mapping, pool->mapping_pool);
1593 mempool_destroy(pool->mapping_pool);
1594 dm_deferred_set_destroy(pool->shared_read_ds);
1595 dm_deferred_set_destroy(pool->all_io_ds);
1599 static struct kmem_cache *_new_mapping_cache;
1601 static struct pool *pool_create(struct mapped_device *pool_md,
1602 struct block_device *metadata_dev,
1603 unsigned long block_size,
1604 int read_only, char **error)
1609 struct dm_pool_metadata *pmd;
1610 bool format_device = read_only ? false : true;
1612 pmd = dm_pool_metadata_open(metadata_dev, block_size, format_device);
1614 *error = "Error creating metadata object";
1615 return (struct pool *)pmd;
1618 pool = kmalloc(sizeof(*pool), GFP_KERNEL);
1620 *error = "Error allocating memory for pool";
1621 err_p = ERR_PTR(-ENOMEM);
1626 pool->sectors_per_block = block_size;
1627 if (block_size & (block_size - 1))
1628 pool->sectors_per_block_shift = -1;
1630 pool->sectors_per_block_shift = __ffs(block_size);
1631 pool->low_water_blocks = 0;
1632 pool_features_init(&pool->pf);
1633 pool->prison = dm_bio_prison_create(PRISON_CELLS);
1634 if (!pool->prison) {
1635 *error = "Error creating pool's bio prison";
1636 err_p = ERR_PTR(-ENOMEM);
1640 pool->copier = dm_kcopyd_client_create();
1641 if (IS_ERR(pool->copier)) {
1642 r = PTR_ERR(pool->copier);
1643 *error = "Error creating pool's kcopyd client";
1645 goto bad_kcopyd_client;
1649 * Create singlethreaded workqueue that will service all devices
1650 * that use this metadata.
1652 pool->wq = alloc_ordered_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM);
1654 *error = "Error creating pool's workqueue";
1655 err_p = ERR_PTR(-ENOMEM);
1659 INIT_WORK(&pool->worker, do_worker);
1660 INIT_DELAYED_WORK(&pool->waker, do_waker);
1661 spin_lock_init(&pool->lock);
1662 bio_list_init(&pool->deferred_bios);
1663 bio_list_init(&pool->deferred_flush_bios);
1664 INIT_LIST_HEAD(&pool->prepared_mappings);
1665 INIT_LIST_HEAD(&pool->prepared_discards);
1666 pool->low_water_triggered = 0;
1667 pool->no_free_space = 0;
1668 bio_list_init(&pool->retry_on_resume_list);
1670 pool->shared_read_ds = dm_deferred_set_create();
1671 if (!pool->shared_read_ds) {
1672 *error = "Error creating pool's shared read deferred set";
1673 err_p = ERR_PTR(-ENOMEM);
1674 goto bad_shared_read_ds;
1677 pool->all_io_ds = dm_deferred_set_create();
1678 if (!pool->all_io_ds) {
1679 *error = "Error creating pool's all io deferred set";
1680 err_p = ERR_PTR(-ENOMEM);
1684 pool->next_mapping = NULL;
1685 pool->mapping_pool = mempool_create_slab_pool(MAPPING_POOL_SIZE,
1686 _new_mapping_cache);
1687 if (!pool->mapping_pool) {
1688 *error = "Error creating pool's mapping mempool";
1689 err_p = ERR_PTR(-ENOMEM);
1690 goto bad_mapping_pool;
1693 pool->ref_count = 1;
1694 pool->last_commit_jiffies = jiffies;
1695 pool->pool_md = pool_md;
1696 pool->md_dev = metadata_dev;
1697 __pool_table_insert(pool);
1702 dm_deferred_set_destroy(pool->all_io_ds);
1704 dm_deferred_set_destroy(pool->shared_read_ds);
1706 destroy_workqueue(pool->wq);
1708 dm_kcopyd_client_destroy(pool->copier);
1710 dm_bio_prison_destroy(pool->prison);
1714 if (dm_pool_metadata_close(pmd))
1715 DMWARN("%s: dm_pool_metadata_close() failed.", __func__);
1720 static void __pool_inc(struct pool *pool)
1722 BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex));
1726 static void __pool_dec(struct pool *pool)
1728 BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex));
1729 BUG_ON(!pool->ref_count);
1730 if (!--pool->ref_count)
1731 __pool_destroy(pool);
1734 static struct pool *__pool_find(struct mapped_device *pool_md,
1735 struct block_device *metadata_dev,
1736 unsigned long block_size, int read_only,
1737 char **error, int *created)
1739 struct pool *pool = __pool_table_lookup_metadata_dev(metadata_dev);
1742 if (pool->pool_md != pool_md) {
1743 *error = "metadata device already in use by a pool";
1744 return ERR_PTR(-EBUSY);
1749 pool = __pool_table_lookup(pool_md);
1751 if (pool->md_dev != metadata_dev) {
1752 *error = "different pool cannot replace a pool";
1753 return ERR_PTR(-EINVAL);
1758 pool = pool_create(pool_md, metadata_dev, block_size, read_only, error);
1766 /*----------------------------------------------------------------
1767 * Pool target methods
1768 *--------------------------------------------------------------*/
1769 static void pool_dtr(struct dm_target *ti)
1771 struct pool_c *pt = ti->private;
1773 mutex_lock(&dm_thin_pool_table.mutex);
1775 unbind_control_target(pt->pool, ti);
1776 __pool_dec(pt->pool);
1777 dm_put_device(ti, pt->metadata_dev);
1778 dm_put_device(ti, pt->data_dev);
1781 mutex_unlock(&dm_thin_pool_table.mutex);
1784 static int parse_pool_features(struct dm_arg_set *as, struct pool_features *pf,
1785 struct dm_target *ti)
1789 const char *arg_name;
1791 static struct dm_arg _args[] = {
1792 {0, 3, "Invalid number of pool feature arguments"},
1796 * No feature arguments supplied.
1801 r = dm_read_arg_group(_args, as, &argc, &ti->error);
1805 while (argc && !r) {
1806 arg_name = dm_shift_arg(as);
1809 if (!strcasecmp(arg_name, "skip_block_zeroing"))
1810 pf->zero_new_blocks = false;
1812 else if (!strcasecmp(arg_name, "ignore_discard"))
1813 pf->discard_enabled = false;
1815 else if (!strcasecmp(arg_name, "no_discard_passdown"))
1816 pf->discard_passdown = false;
1818 else if (!strcasecmp(arg_name, "read_only"))
1819 pf->mode = PM_READ_ONLY;
1822 ti->error = "Unrecognised pool feature requested";
1832 * thin-pool <metadata dev> <data dev>
1833 * <data block size (sectors)>
1834 * <low water mark (blocks)>
1835 * [<#feature args> [<arg>]*]
1837 * Optional feature arguments are:
1838 * skip_block_zeroing: skips the zeroing of newly-provisioned blocks.
1839 * ignore_discard: disable discard
1840 * no_discard_passdown: don't pass discards down to the data device
1842 static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
1844 int r, pool_created = 0;
1847 struct pool_features pf;
1848 struct dm_arg_set as;
1849 struct dm_dev *data_dev;
1850 unsigned long block_size;
1851 dm_block_t low_water_blocks;
1852 struct dm_dev *metadata_dev;
1853 sector_t metadata_dev_size;
1854 char b[BDEVNAME_SIZE];
1857 * FIXME Remove validation from scope of lock.
1859 mutex_lock(&dm_thin_pool_table.mutex);
1862 ti->error = "Invalid argument count";
1869 r = dm_get_device(ti, argv[0], FMODE_READ | FMODE_WRITE, &metadata_dev);
1871 ti->error = "Error opening metadata block device";
1875 metadata_dev_size = i_size_read(metadata_dev->bdev->bd_inode) >> SECTOR_SHIFT;
1876 if (metadata_dev_size > THIN_METADATA_MAX_SECTORS_WARNING)
1877 DMWARN("Metadata device %s is larger than %u sectors: excess space will not be used.",
1878 bdevname(metadata_dev->bdev, b), THIN_METADATA_MAX_SECTORS);
1880 r = dm_get_device(ti, argv[1], FMODE_READ | FMODE_WRITE, &data_dev);
1882 ti->error = "Error getting data device";
1886 if (kstrtoul(argv[2], 10, &block_size) || !block_size ||
1887 block_size < DATA_DEV_BLOCK_SIZE_MIN_SECTORS ||
1888 block_size > DATA_DEV_BLOCK_SIZE_MAX_SECTORS ||
1889 block_size & (DATA_DEV_BLOCK_SIZE_MIN_SECTORS - 1)) {
1890 ti->error = "Invalid block size";
1895 if (kstrtoull(argv[3], 10, (unsigned long long *)&low_water_blocks)) {
1896 ti->error = "Invalid low water mark";
1902 * Set default pool features.
1904 pool_features_init(&pf);
1906 dm_consume_args(&as, 4);
1907 r = parse_pool_features(&as, &pf, ti);
1911 pt = kzalloc(sizeof(*pt), GFP_KERNEL);
1917 pool = __pool_find(dm_table_get_md(ti->table), metadata_dev->bdev,
1918 block_size, pf.mode == PM_READ_ONLY, &ti->error, &pool_created);
1925 * 'pool_created' reflects whether this is the first table load.
1926 * Top level discard support is not allowed to be changed after
1927 * initial load. This would require a pool reload to trigger thin
1930 if (!pool_created && pf.discard_enabled != pool->pf.discard_enabled) {
1931 ti->error = "Discard support cannot be disabled once enabled";
1933 goto out_flags_changed;
1938 pt->metadata_dev = metadata_dev;
1939 pt->data_dev = data_dev;
1940 pt->low_water_blocks = low_water_blocks;
1941 pt->adjusted_pf = pt->requested_pf = pf;
1942 ti->num_flush_requests = 1;
1945 * Only need to enable discards if the pool should pass
1946 * them down to the data device. The thin device's discard
1947 * processing will cause mappings to be removed from the btree.
1949 if (pf.discard_enabled && pf.discard_passdown) {
1950 ti->num_discard_requests = 1;
1953 * Setting 'discards_supported' circumvents the normal
1954 * stacking of discard limits (this keeps the pool and
1955 * thin devices' discard limits consistent).
1957 ti->discards_supported = true;
1958 ti->discard_zeroes_data_unsupported = true;
1962 pt->callbacks.congested_fn = pool_is_congested;
1963 dm_table_add_target_callbacks(ti->table, &pt->callbacks);
1965 mutex_unlock(&dm_thin_pool_table.mutex);
1974 dm_put_device(ti, data_dev);
1976 dm_put_device(ti, metadata_dev);
1978 mutex_unlock(&dm_thin_pool_table.mutex);
1983 static int pool_map(struct dm_target *ti, struct bio *bio,
1984 union map_info *map_context)
1987 struct pool_c *pt = ti->private;
1988 struct pool *pool = pt->pool;
1989 unsigned long flags;
1992 * As this is a singleton target, ti->begin is always zero.
1994 spin_lock_irqsave(&pool->lock, flags);
1995 bio->bi_bdev = pt->data_dev->bdev;
1996 r = DM_MAPIO_REMAPPED;
1997 spin_unlock_irqrestore(&pool->lock, flags);
2003 * Retrieves the number of blocks of the data device from
2004 * the superblock and compares it to the actual device size,
2005 * thus resizing the data device in case it has grown.
2007 * This both copes with opening preallocated data devices in the ctr
2008 * being followed by a resume
2010 * calling the resume method individually after userspace has
2011 * grown the data device in reaction to a table event.
2013 static int pool_preresume(struct dm_target *ti)
2016 struct pool_c *pt = ti->private;
2017 struct pool *pool = pt->pool;
2018 sector_t data_size = ti->len;
2019 dm_block_t sb_data_size;
2022 * Take control of the pool object.
2024 r = bind_control_target(pool, ti);
2028 (void) sector_div(data_size, pool->sectors_per_block);
2030 r = dm_pool_get_data_dev_size(pool->pmd, &sb_data_size);
2032 DMERR("failed to retrieve data device size");
2036 if (data_size < sb_data_size) {
2037 DMERR("pool target too small, is %llu blocks (expected %llu)",
2038 (unsigned long long)data_size, sb_data_size);
2041 } else if (data_size > sb_data_size) {
2042 r = dm_pool_resize_data_dev(pool->pmd, data_size);
2044 DMERR("failed to resize data device");
2045 /* FIXME Stricter than necessary: Rollback transaction instead here */
2046 set_pool_mode(pool, PM_READ_ONLY);
2050 (void) commit_or_fallback(pool);
2056 static void pool_resume(struct dm_target *ti)
2058 struct pool_c *pt = ti->private;
2059 struct pool *pool = pt->pool;
2060 unsigned long flags;
2062 spin_lock_irqsave(&pool->lock, flags);
2063 pool->low_water_triggered = 0;
2064 pool->no_free_space = 0;
2065 __requeue_bios(pool);
2066 spin_unlock_irqrestore(&pool->lock, flags);
2068 do_waker(&pool->waker.work);
2071 static void pool_postsuspend(struct dm_target *ti)
2073 struct pool_c *pt = ti->private;
2074 struct pool *pool = pt->pool;
2076 cancel_delayed_work(&pool->waker);
2077 flush_workqueue(pool->wq);
2078 (void) commit_or_fallback(pool);
2081 static int check_arg_count(unsigned argc, unsigned args_required)
2083 if (argc != args_required) {
2084 DMWARN("Message received with %u arguments instead of %u.",
2085 argc, args_required);
2092 static int read_dev_id(char *arg, dm_thin_id *dev_id, int warning)
2094 if (!kstrtoull(arg, 10, (unsigned long long *)dev_id) &&
2095 *dev_id <= MAX_DEV_ID)
2099 DMWARN("Message received with invalid device id: %s", arg);
2104 static int process_create_thin_mesg(unsigned argc, char **argv, struct pool *pool)
2109 r = check_arg_count(argc, 2);
2113 r = read_dev_id(argv[1], &dev_id, 1);
2117 r = dm_pool_create_thin(pool->pmd, dev_id);
2119 DMWARN("Creation of new thinly-provisioned device with id %s failed.",
2127 static int process_create_snap_mesg(unsigned argc, char **argv, struct pool *pool)
2130 dm_thin_id origin_dev_id;
2133 r = check_arg_count(argc, 3);
2137 r = read_dev_id(argv[1], &dev_id, 1);
2141 r = read_dev_id(argv[2], &origin_dev_id, 1);
2145 r = dm_pool_create_snap(pool->pmd, dev_id, origin_dev_id);
2147 DMWARN("Creation of new snapshot %s of device %s failed.",
2155 static int process_delete_mesg(unsigned argc, char **argv, struct pool *pool)
2160 r = check_arg_count(argc, 2);
2164 r = read_dev_id(argv[1], &dev_id, 1);
2168 r = dm_pool_delete_thin_device(pool->pmd, dev_id);
2170 DMWARN("Deletion of thin device %s failed.", argv[1]);
2175 static int process_set_transaction_id_mesg(unsigned argc, char **argv, struct pool *pool)
2177 dm_thin_id old_id, new_id;
2180 r = check_arg_count(argc, 3);
2184 if (kstrtoull(argv[1], 10, (unsigned long long *)&old_id)) {
2185 DMWARN("set_transaction_id message: Unrecognised id %s.", argv[1]);
2189 if (kstrtoull(argv[2], 10, (unsigned long long *)&new_id)) {
2190 DMWARN("set_transaction_id message: Unrecognised new id %s.", argv[2]);
2194 r = dm_pool_set_metadata_transaction_id(pool->pmd, old_id, new_id);
2196 DMWARN("Failed to change transaction id from %s to %s.",
2204 static int process_reserve_metadata_snap_mesg(unsigned argc, char **argv, struct pool *pool)
2208 r = check_arg_count(argc, 1);
2212 (void) commit_or_fallback(pool);
2214 r = dm_pool_reserve_metadata_snap(pool->pmd);
2216 DMWARN("reserve_metadata_snap message failed.");
2221 static int process_release_metadata_snap_mesg(unsigned argc, char **argv, struct pool *pool)
2225 r = check_arg_count(argc, 1);
2229 r = dm_pool_release_metadata_snap(pool->pmd);
2231 DMWARN("release_metadata_snap message failed.");
2237 * Messages supported:
2238 * create_thin <dev_id>
2239 * create_snap <dev_id> <origin_id>
2241 * trim <dev_id> <new_size_in_sectors>
2242 * set_transaction_id <current_trans_id> <new_trans_id>
2243 * reserve_metadata_snap
2244 * release_metadata_snap
2246 static int pool_message(struct dm_target *ti, unsigned argc, char **argv)
2249 struct pool_c *pt = ti->private;
2250 struct pool *pool = pt->pool;
2252 if (!strcasecmp(argv[0], "create_thin"))
2253 r = process_create_thin_mesg(argc, argv, pool);
2255 else if (!strcasecmp(argv[0], "create_snap"))
2256 r = process_create_snap_mesg(argc, argv, pool);
2258 else if (!strcasecmp(argv[0], "delete"))
2259 r = process_delete_mesg(argc, argv, pool);
2261 else if (!strcasecmp(argv[0], "set_transaction_id"))
2262 r = process_set_transaction_id_mesg(argc, argv, pool);
2264 else if (!strcasecmp(argv[0], "reserve_metadata_snap"))
2265 r = process_reserve_metadata_snap_mesg(argc, argv, pool);
2267 else if (!strcasecmp(argv[0], "release_metadata_snap"))
2268 r = process_release_metadata_snap_mesg(argc, argv, pool);
2271 DMWARN("Unrecognised thin pool target message received: %s", argv[0]);
2274 (void) commit_or_fallback(pool);
2279 static void emit_flags(struct pool_features *pf, char *result,
2280 unsigned sz, unsigned maxlen)
2282 unsigned count = !pf->zero_new_blocks + !pf->discard_enabled +
2283 !pf->discard_passdown + (pf->mode == PM_READ_ONLY);
2284 DMEMIT("%u ", count);
2286 if (!pf->zero_new_blocks)
2287 DMEMIT("skip_block_zeroing ");
2289 if (!pf->discard_enabled)
2290 DMEMIT("ignore_discard ");
2292 if (!pf->discard_passdown)
2293 DMEMIT("no_discard_passdown ");
2295 if (pf->mode == PM_READ_ONLY)
2296 DMEMIT("read_only ");
2301 * <transaction id> <used metadata sectors>/<total metadata sectors>
2302 * <used data sectors>/<total data sectors> <held metadata root>
2304 static int pool_status(struct dm_target *ti, status_type_t type,
2305 unsigned status_flags, char *result, unsigned maxlen)
2309 uint64_t transaction_id;
2310 dm_block_t nr_free_blocks_data;
2311 dm_block_t nr_free_blocks_metadata;
2312 dm_block_t nr_blocks_data;
2313 dm_block_t nr_blocks_metadata;
2314 dm_block_t held_root;
2315 char buf[BDEVNAME_SIZE];
2316 char buf2[BDEVNAME_SIZE];
2317 struct pool_c *pt = ti->private;
2318 struct pool *pool = pt->pool;
2321 case STATUSTYPE_INFO:
2322 if (get_pool_mode(pool) == PM_FAIL) {
2327 /* Commit to ensure statistics aren't out-of-date */
2328 if (!(status_flags & DM_STATUS_NOFLUSH_FLAG) && !dm_suspended(ti))
2329 (void) commit_or_fallback(pool);
2331 r = dm_pool_get_metadata_transaction_id(pool->pmd,
2336 r = dm_pool_get_free_metadata_block_count(pool->pmd,
2337 &nr_free_blocks_metadata);
2341 r = dm_pool_get_metadata_dev_size(pool->pmd, &nr_blocks_metadata);
2345 r = dm_pool_get_free_block_count(pool->pmd,
2346 &nr_free_blocks_data);
2350 r = dm_pool_get_data_dev_size(pool->pmd, &nr_blocks_data);
2354 r = dm_pool_get_metadata_snap(pool->pmd, &held_root);
2358 DMEMIT("%llu %llu/%llu %llu/%llu ",
2359 (unsigned long long)transaction_id,
2360 (unsigned long long)(nr_blocks_metadata - nr_free_blocks_metadata),
2361 (unsigned long long)nr_blocks_metadata,
2362 (unsigned long long)(nr_blocks_data - nr_free_blocks_data),
2363 (unsigned long long)nr_blocks_data);
2366 DMEMIT("%llu ", held_root);
2370 if (pool->pf.mode == PM_READ_ONLY)
2375 if (!pool->pf.discard_enabled)
2376 DMEMIT("ignore_discard");
2377 else if (pool->pf.discard_passdown)
2378 DMEMIT("discard_passdown");
2380 DMEMIT("no_discard_passdown");
2384 case STATUSTYPE_TABLE:
2385 DMEMIT("%s %s %lu %llu ",
2386 format_dev_t(buf, pt->metadata_dev->bdev->bd_dev),
2387 format_dev_t(buf2, pt->data_dev->bdev->bd_dev),
2388 (unsigned long)pool->sectors_per_block,
2389 (unsigned long long)pt->low_water_blocks);
2390 emit_flags(&pt->requested_pf, result, sz, maxlen);
2397 static int pool_iterate_devices(struct dm_target *ti,
2398 iterate_devices_callout_fn fn, void *data)
2400 struct pool_c *pt = ti->private;
2402 return fn(ti, pt->data_dev, 0, ti->len, data);
2405 static int pool_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
2406 struct bio_vec *biovec, int max_size)
2408 struct pool_c *pt = ti->private;
2409 struct request_queue *q = bdev_get_queue(pt->data_dev->bdev);
2411 if (!q->merge_bvec_fn)
2414 bvm->bi_bdev = pt->data_dev->bdev;
2416 return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
2419 static bool block_size_is_power_of_two(struct pool *pool)
2421 return pool->sectors_per_block_shift >= 0;
2424 static void set_discard_limits(struct pool_c *pt, struct queue_limits *limits)
2426 struct pool *pool = pt->pool;
2427 struct queue_limits *data_limits;
2429 limits->max_discard_sectors = pool->sectors_per_block;
2432 * discard_granularity is just a hint, and not enforced.
2434 if (pt->adjusted_pf.discard_passdown) {
2435 data_limits = &bdev_get_queue(pt->data_dev->bdev)->limits;
2436 limits->discard_granularity = data_limits->discard_granularity;
2437 } else if (block_size_is_power_of_two(pool))
2438 limits->discard_granularity = pool->sectors_per_block << SECTOR_SHIFT;
2441 * Use largest power of 2 that is a factor of sectors_per_block
2442 * but at least DATA_DEV_BLOCK_SIZE_MIN_SECTORS.
2444 limits->discard_granularity = max(1 << (ffs(pool->sectors_per_block) - 1),
2445 DATA_DEV_BLOCK_SIZE_MIN_SECTORS) << SECTOR_SHIFT;
2448 static void pool_io_hints(struct dm_target *ti, struct queue_limits *limits)
2450 struct pool_c *pt = ti->private;
2451 struct pool *pool = pt->pool;
2453 blk_limits_io_min(limits, 0);
2454 blk_limits_io_opt(limits, pool->sectors_per_block << SECTOR_SHIFT);
2457 * pt->adjusted_pf is a staging area for the actual features to use.
2458 * They get transferred to the live pool in bind_control_target()
2459 * called from pool_preresume().
2461 if (!pt->adjusted_pf.discard_enabled)
2464 disable_passdown_if_not_supported(pt);
2466 set_discard_limits(pt, limits);
2469 static struct target_type pool_target = {
2470 .name = "thin-pool",
2471 .features = DM_TARGET_SINGLETON | DM_TARGET_ALWAYS_WRITEABLE |
2472 DM_TARGET_IMMUTABLE,
2473 .version = {1, 6, 0},
2474 .module = THIS_MODULE,
2478 .postsuspend = pool_postsuspend,
2479 .preresume = pool_preresume,
2480 .resume = pool_resume,
2481 .message = pool_message,
2482 .status = pool_status,
2483 .merge = pool_merge,
2484 .iterate_devices = pool_iterate_devices,
2485 .io_hints = pool_io_hints,
2488 /*----------------------------------------------------------------
2489 * Thin target methods
2490 *--------------------------------------------------------------*/
2491 static void thin_dtr(struct dm_target *ti)
2493 struct thin_c *tc = ti->private;
2495 mutex_lock(&dm_thin_pool_table.mutex);
2497 __pool_dec(tc->pool);
2498 dm_pool_close_thin_device(tc->td);
2499 dm_put_device(ti, tc->pool_dev);
2501 dm_put_device(ti, tc->origin_dev);
2504 mutex_unlock(&dm_thin_pool_table.mutex);
2508 * Thin target parameters:
2510 * <pool_dev> <dev_id> [origin_dev]
2512 * pool_dev: the path to the pool (eg, /dev/mapper/my_pool)
2513 * dev_id: the internal device identifier
2514 * origin_dev: a device external to the pool that should act as the origin
2516 * If the pool device has discards disabled, they get disabled for the thin
2519 static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv)
2523 struct dm_dev *pool_dev, *origin_dev;
2524 struct mapped_device *pool_md;
2526 mutex_lock(&dm_thin_pool_table.mutex);
2528 if (argc != 2 && argc != 3) {
2529 ti->error = "Invalid argument count";
2534 tc = ti->private = kzalloc(sizeof(*tc), GFP_KERNEL);
2536 ti->error = "Out of memory";
2542 r = dm_get_device(ti, argv[2], FMODE_READ, &origin_dev);
2544 ti->error = "Error opening origin device";
2545 goto bad_origin_dev;
2547 tc->origin_dev = origin_dev;
2550 r = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &pool_dev);
2552 ti->error = "Error opening pool device";
2555 tc->pool_dev = pool_dev;
2557 if (read_dev_id(argv[1], (unsigned long long *)&tc->dev_id, 0)) {
2558 ti->error = "Invalid device id";
2563 pool_md = dm_get_md(tc->pool_dev->bdev->bd_dev);
2565 ti->error = "Couldn't get pool mapped device";
2570 tc->pool = __pool_table_lookup(pool_md);
2572 ti->error = "Couldn't find pool object";
2574 goto bad_pool_lookup;
2576 __pool_inc(tc->pool);
2578 if (get_pool_mode(tc->pool) == PM_FAIL) {
2579 ti->error = "Couldn't open thin device, Pool is in fail mode";
2583 r = dm_pool_open_thin_device(tc->pool->pmd, tc->dev_id, &tc->td);
2585 ti->error = "Couldn't open thin internal device";
2589 r = dm_set_target_max_io_len(ti, tc->pool->sectors_per_block);
2593 ti->num_flush_requests = 1;
2594 ti->flush_supported = true;
2595 ti->per_bio_data_size = sizeof(struct dm_thin_endio_hook);
2597 /* In case the pool supports discards, pass them on. */
2598 if (tc->pool->pf.discard_enabled) {
2599 ti->discards_supported = true;
2600 ti->num_discard_requests = 1;
2601 ti->discard_zeroes_data_unsupported = true;
2602 /* Discard requests must be split on a block boundary */
2603 ti->split_discard_requests = true;
2608 mutex_unlock(&dm_thin_pool_table.mutex);
2613 __pool_dec(tc->pool);
2617 dm_put_device(ti, tc->pool_dev);
2620 dm_put_device(ti, tc->origin_dev);
2624 mutex_unlock(&dm_thin_pool_table.mutex);
2629 static int thin_map(struct dm_target *ti, struct bio *bio,
2630 union map_info *map_context)
2632 bio->bi_sector = dm_target_offset(ti, bio->bi_sector);
2634 return thin_bio_map(ti, bio, map_context);
2637 static int thin_endio(struct dm_target *ti,
2638 struct bio *bio, int err,
2639 union map_info *map_context)
2641 unsigned long flags;
2642 struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
2643 struct list_head work;
2644 struct dm_thin_new_mapping *m, *tmp;
2645 struct pool *pool = h->tc->pool;
2647 if (h->shared_read_entry) {
2648 INIT_LIST_HEAD(&work);
2649 dm_deferred_entry_dec(h->shared_read_entry, &work);
2651 spin_lock_irqsave(&pool->lock, flags);
2652 list_for_each_entry_safe(m, tmp, &work, list) {
2655 __maybe_add_mapping(m);
2657 spin_unlock_irqrestore(&pool->lock, flags);
2660 if (h->all_io_entry) {
2661 INIT_LIST_HEAD(&work);
2662 dm_deferred_entry_dec(h->all_io_entry, &work);
2663 if (!list_empty(&work)) {
2664 spin_lock_irqsave(&pool->lock, flags);
2665 list_for_each_entry_safe(m, tmp, &work, list)
2666 list_add(&m->list, &pool->prepared_discards);
2667 spin_unlock_irqrestore(&pool->lock, flags);
2675 static void thin_postsuspend(struct dm_target *ti)
2677 if (dm_noflush_suspending(ti))
2678 requeue_io((struct thin_c *)ti->private);
2682 * <nr mapped sectors> <highest mapped sector>
2684 static int thin_status(struct dm_target *ti, status_type_t type,
2685 unsigned status_flags, char *result, unsigned maxlen)
2689 dm_block_t mapped, highest;
2690 char buf[BDEVNAME_SIZE];
2691 struct thin_c *tc = ti->private;
2693 if (get_pool_mode(tc->pool) == PM_FAIL) {
2702 case STATUSTYPE_INFO:
2703 r = dm_thin_get_mapped_count(tc->td, &mapped);
2707 r = dm_thin_get_highest_mapped_block(tc->td, &highest);
2711 DMEMIT("%llu ", mapped * tc->pool->sectors_per_block);
2713 DMEMIT("%llu", ((highest + 1) *
2714 tc->pool->sectors_per_block) - 1);
2719 case STATUSTYPE_TABLE:
2721 format_dev_t(buf, tc->pool_dev->bdev->bd_dev),
2722 (unsigned long) tc->dev_id);
2724 DMEMIT(" %s", format_dev_t(buf, tc->origin_dev->bdev->bd_dev));
2732 static int thin_iterate_devices(struct dm_target *ti,
2733 iterate_devices_callout_fn fn, void *data)
2736 struct thin_c *tc = ti->private;
2737 struct pool *pool = tc->pool;
2740 * We can't call dm_pool_get_data_dev_size() since that blocks. So
2741 * we follow a more convoluted path through to the pool's target.
2744 return 0; /* nothing is bound */
2746 blocks = pool->ti->len;
2747 (void) sector_div(blocks, pool->sectors_per_block);
2749 return fn(ti, tc->pool_dev, 0, pool->sectors_per_block * blocks, data);
2755 * A thin device always inherits its queue limits from its pool.
2757 static void thin_io_hints(struct dm_target *ti, struct queue_limits *limits)
2759 struct thin_c *tc = ti->private;
2761 *limits = bdev_get_queue(tc->pool_dev->bdev)->limits;
2764 static struct target_type thin_target = {
2766 .version = {1, 6, 0},
2767 .module = THIS_MODULE,
2771 .end_io = thin_endio,
2772 .postsuspend = thin_postsuspend,
2773 .status = thin_status,
2774 .iterate_devices = thin_iterate_devices,
2775 .io_hints = thin_io_hints,
2778 /*----------------------------------------------------------------*/
2780 static int __init dm_thin_init(void)
2786 r = dm_register_target(&thin_target);
2790 r = dm_register_target(&pool_target);
2792 goto bad_pool_target;
2796 _new_mapping_cache = KMEM_CACHE(dm_thin_new_mapping, 0);
2797 if (!_new_mapping_cache)
2798 goto bad_new_mapping_cache;
2802 bad_new_mapping_cache:
2803 dm_unregister_target(&pool_target);
2805 dm_unregister_target(&thin_target);
2810 static void dm_thin_exit(void)
2812 dm_unregister_target(&thin_target);
2813 dm_unregister_target(&pool_target);
2815 kmem_cache_destroy(_new_mapping_cache);
2818 module_init(dm_thin_init);
2819 module_exit(dm_thin_exit);
2821 MODULE_DESCRIPTION(DM_NAME " thin provisioning target");
2822 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
2823 MODULE_LICENSE("GPL");