diff options
Diffstat (limited to 'drivers/md/dm-snap.c')
| -rw-r--r-- | drivers/md/dm-snap.c | 1964 |
1 files changed, 1497 insertions, 467 deletions
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c index 4dc8a43c034..5bd2290cfb1 100644 --- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -7,8 +7,8 @@ */ #include <linux/blkdev.h> -#include <linux/ctype.h> #include <linux/device-mapper.h> +#include <linux/delay.h> #include <linux/fs.h> #include <linux/init.h> #include <linux/kdev_t.h> @@ -18,62 +18,163 @@ #include <linux/slab.h> #include <linux/vmalloc.h> #include <linux/log2.h> +#include <linux/dm-kcopyd.h> -#include "dm-snap.h" -#include "dm-bio-list.h" -#include "kcopyd.h" +#include "dm-exception-store.h" #define DM_MSG_PREFIX "snapshots" -/* - * The percentage increment we will wake up users at - */ -#define WAKE_UP_PERCENT 5 +static const char dm_snapshot_merge_target_name[] = "snapshot-merge"; -/* - * kcopyd priority of snapshot operations - */ -#define SNAPSHOT_COPY_PRIORITY 2 +#define dm_target_is_snapshot_merge(ti) \ + ((ti)->type->name == dm_snapshot_merge_target_name) /* - * Each snapshot reserves this many pages for io + * The size of the mempool used to track chunks in use. */ -#define SNAPSHOT_PAGES 256 +#define MIN_IOS 256 -static struct workqueue_struct *ksnapd; -static void flush_queued_bios(struct work_struct *work); +#define DM_TRACKED_CHUNK_HASH_SIZE 16 +#define DM_TRACKED_CHUNK_HASH(x) ((unsigned long)(x) & \ + (DM_TRACKED_CHUNK_HASH_SIZE - 1)) -struct dm_snap_pending_exception { - struct dm_snap_exception e; +struct dm_exception_table { + uint32_t hash_mask; + unsigned hash_shift; + struct list_head *table; +}; + +struct dm_snapshot { + struct rw_semaphore lock; + + struct dm_dev *origin; + struct dm_dev *cow; + + struct dm_target *ti; + + /* List of snapshots per Origin */ + struct list_head list; /* - * Origin buffers waiting for this to complete are held - * in a bio list + * You can't use a snapshot if this is 0 (e.g. if full). + * A snapshot-merge target never clears this. */ - struct bio_list origin_bios; - struct bio_list snapshot_bios; + int valid; + + /* Origin writes don't trigger exceptions until this is set */ + int active; + + atomic_t pending_exceptions_count; + + /* Protected by "lock" */ + sector_t exception_start_sequence; + + /* Protected by kcopyd single-threaded callback */ + sector_t exception_complete_sequence; /* - * Short-term queue of pending exceptions prior to submission. + * A list of pending exceptions that completed out of order. + * Protected by kcopyd single-threaded callback. */ - struct list_head list; + struct list_head out_of_order_list; + + mempool_t *pending_pool; + + struct dm_exception_table pending; + struct dm_exception_table complete; + + /* + * pe_lock protects all pending_exception operations and access + * as well as the snapshot_bios list. + */ + spinlock_t pe_lock; + + /* Chunks with outstanding reads */ + spinlock_t tracked_chunk_lock; + struct hlist_head tracked_chunk_hash[DM_TRACKED_CHUNK_HASH_SIZE]; + + /* The on disk metadata handler */ + struct dm_exception_store *store; + + struct dm_kcopyd_client *kcopyd_client; + + /* Wait for events based on state_bits */ + unsigned long state_bits; + + /* Range of chunks currently being merged. */ + chunk_t first_merging_chunk; + int num_merging_chunks; + + /* + * The merge operation failed if this flag is set. + * Failure modes are handled as follows: + * - I/O error reading the header + * => don't load the target; abort. + * - Header does not have "valid" flag set + * => use the origin; forget about the snapshot. + * - I/O error when reading exceptions + * => don't load the target; abort. + * (We can't use the intermediate origin state.) + * - I/O error while merging + * => stop merging; set merge_failed; process I/O normally. + */ + int merge_failed; + + /* + * Incoming bios that overlap with chunks being merged must wait + * for them to be committed. + */ + struct bio_list bios_queued_during_merge; +}; + +/* + * state_bits: + * RUNNING_MERGE - Merge operation is in progress. + * SHUTDOWN_MERGE - Set to signal that merge needs to be stopped; + * cleared afterwards. + */ +#define RUNNING_MERGE 0 +#define SHUTDOWN_MERGE 1 + +DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(snapshot_copy_throttle, + "A percentage of time allocated for copy on write"); + +struct dm_dev *dm_snap_origin(struct dm_snapshot *s) +{ + return s->origin; +} +EXPORT_SYMBOL(dm_snap_origin); + +struct dm_dev *dm_snap_cow(struct dm_snapshot *s) +{ + return s->cow; +} +EXPORT_SYMBOL(dm_snap_cow); +static sector_t chunk_to_sector(struct dm_exception_store *store, + chunk_t chunk) +{ + return chunk << store->chunk_shift; +} + +static int bdev_equal(struct block_device *lhs, struct block_device *rhs) +{ /* - * The primary pending_exception is the one that holds - * the ref_count and the list of origin_bios for a - * group of pending_exceptions. It is always last to get freed. - * These fields get set up when writing to the origin. + * There is only ever one instance of a particular block + * device so we can compare pointers safely. */ - struct dm_snap_pending_exception *primary_pe; + return lhs == rhs; +} + +struct dm_snap_pending_exception { + struct dm_exception e; /* - * Number of pending_exceptions processing this chunk. - * When this drops to zero we must complete the origin bios. - * If incrementing or decrementing this, hold pe->snap->lock for - * the sibling concerned and not pe->primary_pe->snap->lock unless - * they are the same. + * Origin buffers waiting for this to complete are held + * in a bio list */ - atomic_t ref_count; + struct bio_list origin_bios; + struct bio_list snapshot_bios; /* Pointer back to snapshot context */ struct dm_snapshot *snap; @@ -83,6 +184,21 @@ struct dm_snap_pending_exception { * kcopyd. */ int started; + + /* There was copying error. */ + int copy_error; + + /* A sequence number, it is used for in-order completion. */ + sector_t exception_sequence; + + struct list_head out_of_order_entry; + + /* + * For writing a complete chunk, bypassing the copy. + */ + struct bio *full_bio; + bio_end_io_t *full_bio_end_io; + void *full_bio_private; }; /* @@ -91,7 +207,75 @@ struct dm_snap_pending_exception { */ static struct kmem_cache *exception_cache; static struct kmem_cache *pending_cache; -static mempool_t *pending_pool; + +struct dm_snap_tracked_chunk { + struct hlist_node node; + chunk_t chunk; +}; + +static void init_tracked_chunk(struct bio *bio) +{ + struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk)); + INIT_HLIST_NODE(&c->node); +} + +static bool is_bio_tracked(struct bio *bio) +{ + struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk)); + return !hlist_unhashed(&c->node); +} + +static void track_chunk(struct dm_snapshot *s, struct bio *bio, chunk_t chunk) +{ + struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk)); + + c->chunk = chunk; + + spin_lock_irq(&s->tracked_chunk_lock); + hlist_add_head(&c->node, + &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)]); + spin_unlock_irq(&s->tracked_chunk_lock); +} + +static void stop_tracking_chunk(struct dm_snapshot *s, struct bio *bio) +{ + struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk)); + unsigned long flags; + + spin_lock_irqsave(&s->tracked_chunk_lock, flags); + hlist_del(&c->node); + spin_unlock_irqrestore(&s->tracked_chunk_lock, flags); +} + +static int __chunk_is_tracked(struct dm_snapshot *s, chunk_t chunk) +{ + struct dm_snap_tracked_chunk *c; + int found = 0; + + spin_lock_irq(&s->tracked_chunk_lock); + + hlist_for_each_entry(c, + &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)], node) { + if (c->chunk == chunk) { + found = 1; + break; + } + } + + spin_unlock_irq(&s->tracked_chunk_lock); + + return found; +} + +/* + * This conflicting I/O is extremely improbable in the caller, + * so msleep(1) is sufficient and there is no need for a wait queue. + */ +static void __check_for_conflicting_io(struct dm_snapshot *s, chunk_t chunk) +{ + while (__chunk_is_tracked(s, chunk)) + msleep(1); +} /* * One of these per registered origin, held in the snapshot_origins hash @@ -115,6 +299,10 @@ struct origin { static struct list_head *_origins; static struct rw_semaphore _origins_lock; +static DECLARE_WAIT_QUEUE_HEAD(_pending_exceptions_done); +static DEFINE_SPINLOCK(_pending_exceptions_done_spinlock); +static uint64_t _pending_exceptions_done_count; + static int init_origin_hash(void) { int i; @@ -163,24 +351,149 @@ static void __insert_origin(struct origin *o) } /* + * _origins_lock must be held when calling this function. + * Returns number of snapshots registered using the supplied cow device, plus: + * snap_src - a snapshot suitable for use as a source of exception handover + * snap_dest - a snapshot capable of receiving exception handover. + * snap_merge - an existing snapshot-merge target linked to the same origin. + * There can be at most one snapshot-merge target. The parameter is optional. + * + * Possible return values and states of snap_src and snap_dest. + * 0: NULL, NULL - first new snapshot + * 1: snap_src, NULL - normal snapshot + * 2: snap_src, snap_dest - waiting for handover + * 2: snap_src, NULL - handed over, waiting for old to be deleted + * 1: NULL, snap_dest - source got destroyed without handover + */ +static int __find_snapshots_sharing_cow(struct dm_snapshot *snap, + struct dm_snapshot **snap_src, + struct dm_snapshot **snap_dest, + struct dm_snapshot **snap_merge) +{ + struct dm_snapshot *s; + struct origin *o; + int count = 0; + int active; + + o = __lookup_origin(snap->origin->bdev); + if (!o) + goto out; + + list_for_each_entry(s, &o->snapshots, list) { + if (dm_target_is_snapshot_merge(s->ti) && snap_merge) + *snap_merge = s; + if (!bdev_equal(s->cow->bdev, snap->cow->bdev)) + continue; + + down_read(&s->lock); + active = s->active; + up_read(&s->lock); + + if (active) { + if (snap_src) + *snap_src = s; + } else if (snap_dest) + *snap_dest = s; + + count++; + } + +out: + return count; +} + +/* + * On success, returns 1 if this snapshot is a handover destination, + * otherwise returns 0. + */ +static int __validate_exception_handover(struct dm_snapshot *snap) +{ + struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; + struct dm_snapshot *snap_merge = NULL; + + /* Does snapshot need exceptions handed over to it? */ + if ((__find_snapshots_sharing_cow(snap, &snap_src, &snap_dest, + &snap_merge) == 2) || + snap_dest) { + snap->ti->error = "Snapshot cow pairing for exception " + "table handover failed"; + return -EINVAL; + } + + /* + * If no snap_src was found, snap cannot become a handover + * destination. + */ + if (!snap_src) + return 0; + + /* + * Non-snapshot-merge handover? + */ + if (!dm_target_is_snapshot_merge(snap->ti)) + return 1; + + /* + * Do not allow more than one merging snapshot. + */ + if (snap_merge) { + snap->ti->error = "A snapshot is already merging."; + return -EINVAL; + } + + if (!snap_src->store->type->prepare_merge || + !snap_src->store->type->commit_merge) { + snap->ti->error = "Snapshot exception store does not " + "support snapshot-merge."; + return -EINVAL; + } + + return 1; +} + +static void __insert_snapshot(struct origin *o, struct dm_snapshot *s) +{ + struct dm_snapshot *l; + + /* Sort the list according to chunk size, largest-first smallest-last */ + list_for_each_entry(l, &o->snapshots, list) + if (l->store->chunk_size < s->store->chunk_size) + break; + list_add_tail(&s->list, &l->list); +} + +/* * Make a note of the snapshot and its origin so we can look it * up when the origin has a write on it. + * + * Also validate snapshot exception store handovers. + * On success, returns 1 if this registration is a handover destination, + * otherwise returns 0. */ static int register_snapshot(struct dm_snapshot *snap) { - struct origin *o; + struct origin *o, *new_o = NULL; struct block_device *bdev = snap->origin->bdev; + int r = 0; + + new_o = kmalloc(sizeof(*new_o), GFP_KERNEL); + if (!new_o) + return -ENOMEM; down_write(&_origins_lock); - o = __lookup_origin(bdev); - if (!o) { + r = __validate_exception_handover(snap); + if (r < 0) { + kfree(new_o); + goto out; + } + + o = __lookup_origin(bdev); + if (o) + kfree(new_o); + else { /* New origin */ - o = kmalloc(sizeof(*o), GFP_KERNEL); - if (!o) { - up_write(&_origins_lock); - return -ENOMEM; - } + o = new_o; /* Initialise the struct */ INIT_LIST_HEAD(&o->snapshots); @@ -189,10 +502,27 @@ static int register_snapshot(struct dm_snapshot *snap) __insert_origin(o); } - list_add_tail(&snap->list, &o->snapshots); + __insert_snapshot(o, snap); + +out: + up_write(&_origins_lock); + + return r; +} + +/* + * Move snapshot to correct place in list according to chunk size. + */ +static void reregister_snapshot(struct dm_snapshot *s) +{ + struct block_device *bdev = s->origin->bdev; + + down_write(&_origins_lock); + + list_del(&s->list); + __insert_snapshot(__lookup_origin(bdev), s); up_write(&_origins_lock); - return 0; } static void unregister_snapshot(struct dm_snapshot *s) @@ -203,7 +533,7 @@ static void unregister_snapshot(struct dm_snapshot *s) o = __lookup_origin(s->origin->bdev); list_del(&s->list); - if (list_empty(&o->snapshots)) { + if (o && list_empty(&o->snapshots)) { list_del(&o->hash_list); kfree(o); } @@ -216,8 +546,8 @@ static void unregister_snapshot(struct dm_snapshot *s) * The lowest hash_shift bits of the chunk number are ignored, allowing * some consecutive chunks to be grouped together. */ -static int init_exception_table(struct exception_table *et, uint32_t size, - unsigned hash_shift) +static int dm_exception_table_init(struct dm_exception_table *et, + uint32_t size, unsigned hash_shift) { unsigned int i; @@ -233,10 +563,11 @@ static int init_exception_table(struct exception_table *et, uint32_t size, return 0; } -static void exit_exception_table(struct exception_table *et, struct kmem_cache *mem) +static void dm_exception_table_exit(struct dm_exception_table *et, + struct kmem_cache *mem) { struct list_head *slot; - struct dm_snap_exception *ex, *next; + struct dm_exception *ex, *next; int i, size; size = et->hash_mask + 1; @@ -250,19 +581,12 @@ static void exit_exception_table(struct exception_table *et, struct kmem_cache * vfree(et->table); } -static uint32_t exception_hash(struct exception_table *et, chunk_t chunk) +static uint32_t exception_hash(struct dm_exception_table *et, chunk_t chunk) { return (chunk >> et->hash_shift) & et->hash_mask; } -static void insert_exception(struct exception_table *eh, - struct dm_snap_exception *e) -{ - struct list_head *l = &eh->table[exception_hash(eh, e->old_chunk)]; - list_add(&e->hash_list, l); -} - -static void remove_exception(struct dm_snap_exception *e) +static void dm_remove_exception(struct dm_exception *e) { list_del(&e->hash_list); } @@ -271,11 +595,11 @@ static void remove_exception(struct dm_snap_exception *e) * Return the exception data for a sector, or NULL if not * remapped. */ -static struct dm_snap_exception *lookup_exception(struct exception_table *et, - chunk_t chunk) +static struct dm_exception *dm_lookup_exception(struct dm_exception_table *et, + chunk_t chunk) { struct list_head *slot; - struct dm_snap_exception *e; + struct dm_exception *e; slot = &et->table[exception_hash(et, chunk)]; list_for_each_entry (e, slot, hash_list) @@ -286,38 +610,47 @@ static struct dm_snap_exception *lookup_exception(struct exception_table *et, return NULL; } -static struct dm_snap_exception *alloc_exception(void) +static struct dm_exception *alloc_completed_exception(gfp_t gfp) { - struct dm_snap_exception *e; + struct dm_exception *e; - e = kmem_cache_alloc(exception_cache, GFP_NOIO); - if (!e) + e = kmem_cache_alloc(exception_cache, gfp); + if (!e && gfp == GFP_NOIO) e = kmem_cache_alloc(exception_cache, GFP_ATOMIC); return e; } -static void free_exception(struct dm_snap_exception *e) +static void free_completed_exception(struct dm_exception *e) { kmem_cache_free(exception_cache, e); } -static struct dm_snap_pending_exception *alloc_pending_exception(void) +static struct dm_snap_pending_exception *alloc_pending_exception(struct dm_snapshot *s) { - return mempool_alloc(pending_pool, GFP_NOIO); + struct dm_snap_pending_exception *pe = mempool_alloc(s->pending_pool, + GFP_NOIO); + + atomic_inc(&s->pending_exceptions_count); + pe->snap = s; + + return pe; } static void free_pending_exception(struct dm_snap_pending_exception *pe) { - mempool_free(pe, pending_pool); + struct dm_snapshot *s = pe->snap; + + mempool_free(pe, s->pending_pool); + smp_mb__before_atomic(); + atomic_dec(&s->pending_exceptions_count); } -static void insert_completed_exception(struct dm_snapshot *s, - struct dm_snap_exception *new_e) +static void dm_insert_exception(struct dm_exception_table *eh, + struct dm_exception *new_e) { - struct exception_table *eh = &s->complete; struct list_head *l; - struct dm_snap_exception *e = NULL; + struct dm_exception *e = NULL; l = &eh->table[exception_hash(eh, new_e->old_chunk)]; @@ -333,7 +666,7 @@ static void insert_completed_exception(struct dm_snapshot *s, new_e->new_chunk == (dm_chunk_number(e->new_chunk) + dm_consecutive_chunk_count(e) + 1)) { dm_consecutive_chunk_count_inc(e); - free_exception(new_e); + free_completed_exception(new_e); return; } @@ -343,7 +676,7 @@ static void insert_completed_exception(struct dm_snapshot *s, dm_consecutive_chunk_count_inc(e); e->old_chunk--; e->new_chunk--; - free_exception(new_e); + free_completed_exception(new_e); return; } @@ -355,11 +688,16 @@ out: list_add(&new_e->hash_list, e ? &e->hash_list : l); } -int dm_add_exception(struct dm_snapshot *s, chunk_t old, chunk_t new) +/* + * Callback used by the exception stores to load exceptions when + * initialising. + */ +static int dm_add_exception(void *context, chunk_t old, chunk_t new) { - struct dm_snap_exception *e; + struct dm_snapshot *s = context; + struct dm_exception *e; - e = alloc_exception(); + e = alloc_completed_exception(GFP_KERNEL); if (!e) return -ENOMEM; @@ -368,12 +706,29 @@ int dm_add_exception(struct dm_snapshot *s, chunk_t old, chunk_t new) /* Consecutive_count is implicitly initialised to zero */ e->new_chunk = new; - insert_completed_exception(s, e); + dm_insert_exception(&s->complete, e); return 0; } /* + * Return a minimum chunk size of all snapshots that have the specified origin. + * Return zero if the origin has no snapshots. + */ +static uint32_t __minimum_chunk_size(struct origin *o) +{ + struct dm_snapshot *snap; + unsigned chunk_size = 0; + + if (o) + list_for_each_entry(snap, &o->snapshots, list) + chunk_size = min_not_zero(chunk_size, + snap->store->chunk_size); + + return (uint32_t) chunk_size; +} + +/* * Hard coded magic. */ static int calc_max_buckets(void) @@ -390,22 +745,23 @@ static int calc_max_buckets(void) */ static int init_hash_tables(struct dm_snapshot *s) { - sector_t hash_size, cow_dev_size, origin_dev_size, max_buckets; + sector_t hash_size, cow_dev_size, max_buckets; /* * Calculate based on the size of the original volume or * the COW volume... */ cow_dev_size = get_dev_size(s->cow->bdev); - origin_dev_size = get_dev_size(s->origin->bdev); max_buckets = calc_max_buckets(); - hash_size = min(origin_dev_size, cow_dev_size) >> s->chunk_shift; + hash_size = cow_dev_size >> s->store->chunk_shift; hash_size = min(hash_size, max_buckets); + if (hash_size < 64) + hash_size = 64; hash_size = rounddown_pow_of_two(hash_size); - if (init_exception_table(&s->complete, hash_size, - DM_CHUNK_CONSECUTIVE_BITS)) + if (dm_exception_table_init(&s->complete, hash_size, + DM_CHUNK_CONSECUTIVE_BITS)) return -ENOMEM; /* @@ -416,227 +772,551 @@ static int init_hash_tables(struct dm_snapshot *s) if (hash_size < 64) hash_size = 64; - if (init_exception_table(&s->pending, hash_size, 0)) { - exit_exception_table(&s->complete, exception_cache); + if (dm_exception_table_init(&s->pending, hash_size, 0)) { + dm_exception_table_exit(&s->complete, exception_cache); return -ENOMEM; } return 0; } -/* - * Round a number up to the nearest 'size' boundary. size must - * be a power of 2. - */ -static ulong round_up(ulong n, ulong size) +static void merge_shutdown(struct dm_snapshot *s) { - size--; - return (n + size) & ~size; + clear_bit_unlock(RUNNING_MERGE, &s->state_bits); + smp_mb__after_atomic(); + wake_up_bit(&s->state_bits, RUNNING_MERGE); } -static int set_chunk_size(struct dm_snapshot *s, const char *chunk_size_arg, - char **error) +static struct bio *__release_queued_bios_after_merge(struct dm_snapshot *s) +{ + s->first_merging_chunk = 0; + s->num_merging_chunks = 0; + + return bio_list_get(&s->bios_queued_during_merge); +} + +/* + * Remove one chunk from the index of completed exceptions. + */ +static int __remove_single_exception_chunk(struct dm_snapshot *s, + chunk_t old_chunk) { - unsigned long chunk_size; - char *value; + struct dm_exception *e; - chunk_size = simple_strtoul(chunk_size_arg, &value, 10); - if (*chunk_size_arg == '\0' || *value != '\0') { - *error = "Invalid chunk size"; + e = dm_lookup_exception(&s->complete, old_chunk); + if (!e) { + DMERR("Corruption detected: exception for block %llu is " + "on disk but not in memory", + (unsigned long long)old_chunk); return -EINVAL; } - if (!chunk_size) { - s->chunk_size = s->chunk_mask = s->chunk_shift = 0; + /* + * If this is the only chunk using this exception, remove exception. + */ + if (!dm_consecutive_chunk_count(e)) { + dm_remove_exception(e); + free_completed_exception(e); return 0; } /* - * Chunk size must be multiple of page size. Silently - * round up if it's not. + * The chunk may be either at the beginning or the end of a + * group of consecutive chunks - never in the middle. We are + * removing chunks in the opposite order to that in which they + * were added, so this should always be true. + * Decrement the consecutive chunk counter and adjust the + * starting point if necessary. */ - chunk_size = round_up(chunk_size, PAGE_SIZE >> 9); - - /* Check chunk_size is a power of 2 */ - if (!is_power_of_2(chunk_size)) { - *error = "Chunk size is not a power of 2"; + if (old_chunk == e->old_chunk) { + e->old_chunk++; + e->new_chunk++; + } else if (old_chunk != e->old_chunk + + dm_consecutive_chunk_count(e)) { + DMERR("Attempt to merge block %llu from the " + "middle of a chunk range [%llu - %llu]", + (unsigned long long)old_chunk, + (unsigned long long)e->old_chunk, + (unsigned long long) + e->old_chunk + dm_consecutive_chunk_count(e)); return -EINVAL; } - /* Validate the chunk size against the device block size */ - if (chunk_size % (bdev_hardsect_size(s->cow->bdev) >> 9)) { - *error = "Chunk size is not a multiple of device blocksize"; - return -EINVAL; + dm_consecutive_chunk_count_dec(e); + + return 0; +} + +static void flush_bios(struct bio *bio); + +static int remove_single_exception_chunk(struct dm_snapshot *s) +{ + struct bio *b = NULL; + int r; + chunk_t old_chunk = s->first_merging_chunk + s->num_merging_chunks - 1; + + down_write(&s->lock); + + /* + * Process chunks (and associated exceptions) in reverse order + * so that dm_consecutive_chunk_count_dec() accounting works. + */ + do { + r = __remove_single_exception_chunk(s, old_chunk); + if (r) + goto out; + } while (old_chunk-- > s->first_merging_chunk); + + b = __release_queued_bios_after_merge(s); + +out: + up_write(&s->lock); + if (b) + flush_bios(b); + + return r; +} + +static int origin_write_extent(struct dm_snapshot *merging_snap, + sector_t sector, unsigned chunk_size); + +static void merge_callback(int read_err, unsigned long write_err, + void *context); + +static uint64_t read_pending_exceptions_done_count(void) +{ + uint64_t pending_exceptions_done; + + spin_lock(&_pending_exceptions_done_spinlock); + pending_exceptions_done = _pending_exceptions_done_count; + spin_unlock(&_pending_exceptions_done_spinlock); + + return pending_exceptions_done; +} + +static void increment_pending_exceptions_done_count(void) +{ + spin_lock(&_pending_exceptions_done_spinlock); + _pending_exceptions_done_count++; + spin_unlock(&_pending_exceptions_done_spinlock); + + wake_up_all(&_pending_exceptions_done); +} + +static void snapshot_merge_next_chunks(struct dm_snapshot *s) +{ + int i, linear_chunks; + chunk_t old_chunk, new_chunk; + struct dm_io_region src, dest; + sector_t io_size; + uint64_t previous_count; + + BUG_ON(!test_bit(RUNNING_MERGE, &s->state_bits)); + if (unlikely(test_bit(SHUTDOWN_MERGE, &s->state_bits))) + goto shut; + + /* + * valid flag never changes during merge, so no lock required. + */ + if (!s->valid) { + DMERR("Snapshot is invalid: can't merge"); + goto shut; + } + + linear_chunks = s->store->type->prepare_merge(s->store, &old_chunk, + &new_chunk); + if (linear_chunks <= 0) { + if (linear_chunks < 0) { + DMERR("Read error in exception store: " + "shutting down merge"); + down_write(&s->lock); + s->merge_failed = 1; + up_write(&s->lock); + } + goto shut; + } + + /* Adjust old_chunk and new_chunk to reflect start of linear region */ + old_chunk = old_chunk + 1 - linear_chunks; + new_chunk = new_chunk + 1 - linear_chunks; + + /* + * Use one (potentially large) I/O to copy all 'linear_chunks' + * from the exception store to the origin + */ + io_size = linear_chunks * s->store->chunk_size; + + dest.bdev = s->origin->bdev; + dest.sector = chunk_to_sector(s->store, old_chunk); + dest.count = min(io_size, get_dev_size(dest.bdev) - dest.sector); + + src.bdev = s->cow->bdev; + src.sector = chunk_to_sector(s->store, new_chunk); + src.count = dest.count; + + /* + * Reallocate any exceptions needed in other snapshots then + * wait for the pending exceptions to complete. + * Each time any pending exception (globally on the system) + * completes we are woken and repeat the process to find out + * if we can proceed. While this may not seem a particularly + * efficient algorithm, it is not expected to have any + * significant impact on performance. + */ + previous_count = read_pending_exceptions_done_count(); + while (origin_write_extent(s, dest.sector, io_size)) { + wait_event(_pending_exceptions_done, + (read_pending_exceptions_done_count() != + previous_count)); + /* Retry after the wait, until all exceptions are done. */ + previous_count = read_pending_exceptions_done_count(); + } + + down_write(&s->lock); + s->first_merging_chunk = old_chunk; + s->num_merging_chunks = linear_chunks; + up_write(&s->lock); + + /* Wait until writes to all 'linear_chunks' drain */ + for (i = 0; i < linear_chunks; i++) + __check_for_conflicting_io(s, old_chunk + i); + + dm_kcopyd_copy(s->kcopyd_client, &src, 1, &dest, 0, merge_callback, s); + return; + +shut: + merge_shutdown(s); +} + +static void error_bios(struct bio *bio); + +static void merge_callback(int read_err, unsigned long write_err, void *context) +{ + struct dm_snapshot *s = context; + struct bio *b = NULL; + + if (read_err || write_err) { + if (read_err) + DMERR("Read error: shutting down merge."); + else + DMERR("Write error: shutting down merge."); + goto shut; } - s->chunk_size = chunk_size; - s->chunk_mask = chunk_size - 1; - s->chunk_shift = ffs(chunk_size) - 1; + if (s->store->type->commit_merge(s->store, + s->num_merging_chunks) < 0) { + DMERR("Write error in exception store: shutting down merge"); + goto shut; + } + + if (remove_single_exception_chunk(s) < 0) + goto shut; + + snapshot_merge_next_chunks(s); + + return; + +shut: + down_write(&s->lock); + s->merge_failed = 1; + b = __release_queued_bios_after_merge(s); + up_write(&s->lock); + error_bios(b); + + merge_shutdown(s); +} + +static void start_merge(struct dm_snapshot *s) +{ + if (!test_and_set_bit(RUNNING_MERGE, &s->state_bits)) + snapshot_merge_next_chunks(s); +} + +static int wait_schedule(void *ptr) +{ + schedule(); return 0; } /* + * Stop the merging process and wait until it finishes. + */ +static void stop_merge(struct dm_snapshot *s) +{ + set_bit(SHUTDOWN_MERGE, &s->state_bits); + wait_on_bit(&s->state_bits, RUNNING_MERGE, wait_schedule, + TASK_UNINTERRUPTIBLE); + clear_bit(SHUTDOWN_MERGE, &s->state_bits); +} + +/* * Construct a snapshot mapping: <origin_dev> <COW-dev> <p/n> <chunk-size> */ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv) { struct dm_snapshot *s; + int i; int r = -EINVAL; - char persistent; - char *origin_path; - char *cow_path; + char *origin_path, *cow_path; + unsigned args_used, num_flush_bios = 1; + fmode_t origin_mode = FMODE_READ; if (argc != 4) { ti->error = "requires exactly 4 arguments"; r = -EINVAL; - goto bad1; + goto bad; } - origin_path = argv[0]; - cow_path = argv[1]; - persistent = toupper(*argv[2]); - - if (persistent != 'P' && persistent != 'N') { - ti->error = "Persistent flag is not P or N"; - r = -EINVAL; - goto bad1; + if (dm_target_is_snapshot_merge(ti)) { + num_flush_bios = 2; + origin_mode = FMODE_WRITE; } s = kmalloc(sizeof(*s), GFP_KERNEL); - if (s == NULL) { - ti->error = "Cannot allocate snapshot context private " - "structure"; + if (!s) { + ti->error = "Cannot allocate private snapshot structure"; r = -ENOMEM; - goto bad1; + goto bad; } - r = dm_get_device(ti, origin_path, 0, ti->len, FMODE_READ, &s->origin); + origin_path = argv[0]; + argv++; + argc--; + + r = dm_get_device(ti, origin_path, origin_mode, &s->origin); if (r) { ti->error = "Cannot get origin device"; - goto bad2; + goto bad_origin; } - r = dm_get_device(ti, cow_path, 0, 0, - FMODE_READ | FMODE_WRITE, &s->cow); + cow_path = argv[0]; + argv++; + argc--; + + r = dm_get_device(ti, cow_path, dm_table_get_mode(ti->table), &s->cow); if (r) { - dm_put_device(ti, s->origin); ti->error = "Cannot get COW device"; - goto bad2; + goto bad_cow; } - r = set_chunk_size(s, argv[3], &ti->error); - if (r) - goto bad3; + r = dm_exception_store_create(ti, argc, argv, s, &args_used, &s->store); + if (r) { + ti->error = "Couldn't create exception store"; + r = -EINVAL; + goto bad_store; + } - s->type = persistent; + argv += args_used; + argc -= args_used; + s->ti = ti; s->valid = 1; s->active = 0; - s->last_percent = 0; + atomic_set(&s->pending_exceptions_count, 0); + s->exception_start_sequence = 0; + s->exception_complete_sequence = 0; + INIT_LIST_HEAD(&s->out_of_order_list); init_rwsem(&s->lock); + INIT_LIST_HEAD(&s->list); spin_lock_init(&s->pe_lock); - s->table = ti->table; + s->state_bits = 0; + s->merge_failed = 0; + s->first_merging_chunk = 0; + s->num_merging_chunks = 0; + bio_list_init(&s->bios_queued_during_merge); /* Allocate hash table for COW data */ if (init_hash_tables(s)) { ti->error = "Unable to allocate hash table space"; r = -ENOMEM; - goto bad3; + goto bad_hash_tables; } - s->store.snap = s; + s->kcopyd_client = dm_kcopyd_client_create(&dm_kcopyd_throttle); + if (IS_ERR(s->kcopyd_client)) { + r = PTR_ERR(s->kcopyd_client); + ti->error = "Could not create kcopyd client"; + goto bad_kcopyd; + } - if (persistent == 'P') - r = dm_create_persistent(&s->store); - else - r = dm_create_transient(&s->store); + s->pending_pool = mempool_create_slab_pool(MIN_IOS, pending_cache); + if (!s->pending_pool) { + ti->error = "Could not allocate mempool for pending exceptions"; + r = -ENOMEM; + goto bad_pending_pool; + } - if (r) { - ti->error = "Couldn't create exception store"; - r = -EINVAL; - goto bad4; + for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) + INIT_HLIST_HEAD(&s->tracked_chunk_hash[i]); + + spin_lock_init(&s->tracked_chunk_lock); + + ti->private = s; + ti->num_flush_bios = num_flush_bios; + ti->per_bio_data_size = sizeof(struct dm_snap_tracked_chunk); + + /* Add snapshot to the list of snapshots for this origin */ + /* Exceptions aren't triggered till snapshot_resume() is called */ + r = register_snapshot(s); + if (r == -ENOMEM) { + ti->error = "Snapshot origin struct allocation failed"; + goto bad_load_and_register; + } else if (r < 0) { + /* invalid handover, register_snapshot has set ti->error */ + goto bad_load_and_register; } - r = kcopyd_client_create(SNAPSHOT_PAGES, &s->kcopyd_client); - if (r) { - ti->error = "Could not create kcopyd client"; - goto bad5; + /* + * Metadata must only be loaded into one table at once, so skip this + * if metadata will be handed over during resume. + * Chunk size will be set during the handover - set it to zero to + * ensure it's ignored. + */ + if (r > 0) { + s->store->chunk_size = 0; + return 0; } - /* Metadata must only be loaded into one table at once */ - r = s->store.read_metadata(&s->store); + r = s->store->type->read_metadata(s->store, dm_add_exception, + (void *)s); if (r < 0) { ti->error = "Failed to read snapshot metadata"; - goto bad6; + goto bad_read_metadata; } else if (r > 0) { s->valid = 0; DMWARN("Snapshot is marked invalid."); } - bio_list_init(&s->queued_bios); - INIT_WORK(&s->queued_bios_work, flush_queued_bios); - - /* Add snapshot to the list of snapshots for this origin */ - /* Exceptions aren't triggered till snapshot_resume() is called */ - if (register_snapshot(s)) { - r = -EINVAL; - ti->error = "Cannot register snapshot origin"; - goto bad6; + if (!s->store->chunk_size) { + ti->error = "Chunk size not set"; + goto bad_read_metadata; } - ti->private = s; - ti->split_io = s->chunk_size; + r = dm_set_target_max_io_len(ti, s->store->chunk_size); + if (r) + goto bad_read_metadata; return 0; - bad6: - kcopyd_client_destroy(s->kcopyd_client); +bad_read_metadata: + unregister_snapshot(s); + +bad_load_and_register: + mempool_destroy(s->pending_pool); + +bad_pending_pool: + dm_kcopyd_client_destroy(s->kcopyd_client); - bad5: - s->store.destroy(&s->store); +bad_kcopyd: + dm_exception_table_exit(&s->pending, pending_cache); + dm_exception_table_exit(&s->complete, exception_cache); - bad4: - exit_exception_table(&s->pending, pending_cache); - exit_exception_table(&s->complete, exception_cache); +bad_hash_tables: + dm_exception_store_destroy(s->store); - bad3: +bad_store: dm_put_device(ti, s->cow); + +bad_cow: dm_put_device(ti, s->origin); - bad2: +bad_origin: kfree(s); - bad1: +bad: return r; } static void __free_exceptions(struct dm_snapshot *s) { - kcopyd_client_destroy(s->kcopyd_client); + dm_kcopyd_client_destroy(s->kcopyd_client); s->kcopyd_client = NULL; - exit_exception_table(&s->pending, pending_cache); - exit_exception_table(&s->complete, exception_cache); + dm_exception_table_exit(&s->pending, pending_cache); + dm_exception_table_exit(&s->complete, exception_cache); +} + +static void __handover_exceptions(struct dm_snapshot *snap_src, + struct dm_snapshot *snap_dest) +{ + union { + struct dm_exception_table table_swap; + struct dm_exception_store *store_swap; + } u; + + /* + * Swap all snapshot context information between the two instances. + */ + u.table_swap = snap_dest->complete; + snap_dest->complete = snap_src->complete; + snap_src->complete = u.table_swap; + + u.store_swap = snap_dest->store; + snap_dest->store = snap_src->store; + snap_src->store = u.store_swap; + + snap_dest->store->snap = snap_dest; + snap_src->store->snap = snap_src; + + snap_dest->ti->max_io_len = snap_dest->store->chunk_size; + snap_dest->valid = snap_src->valid; - s->store.destroy(&s->store); + /* + * Set source invalid to ensure it receives no further I/O. + */ + snap_src->valid = 0; } static void snapshot_dtr(struct dm_target *ti) { +#ifdef CONFIG_DM_DEBUG + int i; +#endif struct dm_snapshot *s = ti->private; + struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; - flush_workqueue(ksnapd); + down_read(&_origins_lock); + /* Check whether exception handover must be cancelled */ + (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); + if (snap_src && snap_dest && (s == snap_src)) { + down_write(&snap_dest->lock); + snap_dest->valid = 0; + up_write(&snap_dest->lock); + DMERR("Cancelling snapshot handover."); + } + up_read(&_origins_lock); + + if (dm_target_is_snapshot_merge(ti)) + stop_merge(s); /* Prevent further origin writes from using this snapshot. */ /* After this returns there can be no new kcopyd jobs. */ unregister_snapshot(s); + while (atomic_read(&s->pending_exceptions_count)) + msleep(1); + /* + * Ensure instructions in mempool_destroy aren't reordered + * before atomic_read. + */ + smp_mb(); + +#ifdef CONFIG_DM_DEBUG + for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) + BUG_ON(!hlist_empty(&s->tracked_chunk_hash[i])); +#endif + __free_exceptions(s); - dm_put_device(ti, s->origin); + mempool_destroy(s->pending_pool); + + dm_exception_store_destroy(s->store); + dm_put_device(ti, s->cow); + dm_put_device(ti, s->origin); + kfree(s); } @@ -655,18 +1335,24 @@ static void flush_bios(struct bio *bio) } } -static void flush_queued_bios(struct work_struct *work) -{ - struct dm_snapshot *s = - container_of(work, struct dm_snapshot, queued_bios_work); - struct bio *queued_bios; - unsigned long flags; +static int do_origin(struct dm_dev *origin, struct bio *bio); - spin_lock_irqsave(&s->pe_lock, flags); - queued_bios = bio_list_get(&s->queued_bios); - spin_unlock_irqrestore(&s->pe_lock, flags); +/* + * Flush a list of buffers. + */ +static void retry_origin_bios(struct dm_snapshot *s, struct bio *bio) +{ + struct bio *n; + int r; - flush_bios(queued_bios); + while (bio) { + n = bio->bi_next; + bio->bi_next = NULL; + r = do_origin(s->origin, bio); + if (r == DM_MAPIO_REMAPPED) + generic_make_request(bio); + bio = n; + } } /* @@ -694,57 +1380,21 @@ static void __invalidate_snapshot(struct dm_snapshot *s, int err) else if (err == -ENOMEM) DMERR("Invalidating snapshot: Unable to allocate exception."); - if (s->store.drop_snapshot) - s->store.drop_snapshot(&s->store); + if (s->store->type->drop_snapshot) + s->store->type->drop_snapshot(s->store); s->valid = 0; - dm_table_event(s->table); -} - -static void get_pending_exception(struct dm_snap_pending_exception *pe) -{ - atomic_inc(&pe->ref_count); -} - -static struct bio *put_pending_exception(struct dm_snap_pending_exception *pe) -{ - struct dm_snap_pending_exception *primary_pe; - struct bio *origin_bios = NULL; - - primary_pe = pe->primary_pe; - - /* - * If this pe is involved in a write to the origin and - * it is the last sibling to complete then release - * the bios for the original write to the origin. - */ - if (primary_pe && - atomic_dec_and_test(&primary_pe->ref_count)) - origin_bios = bio_list_get(&primary_pe->origin_bios); - - /* - * Free the pe if it's not linked to an origin write or if - * it's not itself a primary pe. - */ - if (!primary_pe || primary_pe != pe) - free_pending_exception(pe); - - /* - * Free the primary pe if nothing references it. - */ - if (primary_pe && !atomic_read(&primary_pe->ref_count)) - free_pending_exception(primary_pe); - - return origin_bios; + dm_table_event(s->ti->table); } static void pending_complete(struct dm_snap_pending_exception *pe, int success) { - struct dm_snap_exception *e; + struct dm_exception *e; struct dm_snapshot *s = pe->snap; struct bio *origin_bios = NULL; struct bio *snapshot_bios = NULL; + struct bio *full_bio = NULL; int error = 0; if (!success) { @@ -755,7 +1405,7 @@ static void pending_complete(struct dm_snap_pending_exception *pe, int success) goto out; } - e = alloc_exception(); + e = alloc_completed_exception(GFP_NOIO); if (!e) { down_write(&s->lock); __invalidate_snapshot(s, -ENOMEM); @@ -766,31 +1416,48 @@ static void pending_complete(struct dm_snap_pending_exception *pe, int success) down_write(&s->lock); if (!s->valid) { - free_exception(e); + free_completed_exception(e); error = 1; goto out; } + /* Check for conflicting reads */ + __check_for_conflicting_io(s, pe->e.old_chunk); + /* * Add a proper exception, and remove the * in-flight exception from the list. */ - insert_completed_exception(s, e); + dm_insert_exception(&s->complete, e); - out: - remove_exception(&pe->e); +out: + dm_remove_exception(&pe->e); snapshot_bios = bio_list_get(&pe->snapshot_bios); - origin_bios = put_pending_exception(pe); + origin_bios = bio_list_get(&pe->origin_bios); + full_bio = pe->full_bio; + if (full_bio) { + full_bio->bi_end_io = pe->full_bio_end_io; + full_bio->bi_private = pe->full_bio_private; + atomic_inc(&full_bio->bi_remaining); + } + free_pending_exception(pe); + + increment_pending_exceptions_done_count(); up_write(&s->lock); /* Submit any pending write bios */ - if (error) + if (error) { + if (full_bio) + bio_io_error(full_bio); error_bios(snapshot_bios); - else + } else { + if (full_bio) + bio_endio(full_bio, 0); flush_bios(snapshot_bios); + } - flush_bios(origin_bios); + retry_origin_bios(s, origin_bios); } static void commit_callback(void *context, int success) @@ -800,6 +1467,19 @@ static void commit_callback(void *context, int success) pending_complete(pe, success); } +static void complete_exception(struct dm_snap_pending_exception *pe) +{ + struct dm_snapshot *s = pe->snap; + + if (unlikely(pe->copy_error)) + pending_complete(pe, 0); + + else + /* Update the metadata if we are persistent */ + s->store->type->commit_exception(s->store, &pe->e, + commit_callback, pe); +} + /* * Called when the copy I/O has finished. kcopyd actually runs * this code so don't block. @@ -809,13 +1489,32 @@ static void copy_callback(int read_err, unsigned long write_err, void *context) struct dm_snap_pending_exception *pe = context; struct dm_snapshot *s = pe->snap; - if (read_err || write_err) - pending_complete(pe, 0); + pe->copy_error = read_err || write_err; - else - /* Update the metadata if we are persistent */ - s->store.commit_exception(&s->store, &pe->e, commit_callback, - pe); + if (pe->exception_sequence == s->exception_complete_sequence) { + s->exception_complete_sequence++; + complete_exception(pe); + + while (!list_empty(&s->out_of_order_list)) { + pe = list_entry(s->out_of_order_list.next, + struct dm_snap_pending_exception, out_of_order_entry); + if (pe->exception_sequence != s->exception_complete_sequence) + break; + s->exception_complete_sequence++; + list_del(&pe->out_of_order_entry); + complete_exception(pe); + } + } else { + struct list_head *lh; + struct dm_snap_pending_exception *pe2; + + list_for_each_prev(lh, &s->out_of_order_list) { + pe2 = list_entry(lh, struct dm_snap_pending_exception, out_of_order_entry); + if (pe2->exception_sequence < pe->exception_sequence) + break; + } + list_add(&pe->out_of_order_entry, lh); + } } /* @@ -824,23 +1523,59 @@ static void copy_callback(int read_err, unsigned long write_err, void *context) static void start_copy(struct dm_snap_pending_exception *pe) { struct dm_snapshot *s = pe->snap; - struct io_region src, dest; + struct dm_io_region src, dest; struct block_device *bdev = s->origin->bdev; sector_t dev_size; dev_size = get_dev_size(bdev); src.bdev = bdev; - src.sector = chunk_to_sector(s, pe->e.old_chunk); - src.count = min(s->chunk_size, dev_size - src.sector); + src.sector = chunk_to_sector(s->store, pe->e.old_chunk); + src.count = min((sector_t)s->store->chunk_size, dev_size - src.sector); dest.bdev = s->cow->bdev; - dest.sector = chunk_to_sector(s, pe->e.new_chunk); + dest.sector = chunk_to_sector(s->store, pe->e.new_chunk); dest.count = src.count; /* Hand over to kcopyd */ - kcopyd_copy(s->kcopyd_client, - &src, 1, &dest, 0, copy_callback, pe); + dm_kcopyd_copy(s->kcopyd_client, &src, 1, &dest, 0, copy_callback, pe); +} + +static void full_bio_end_io(struct bio *bio, int error) +{ + void *callback_data = bio->bi_private; + + dm_kcopyd_do_callback(callback_data, 0, error ? 1 : 0); +} + +static void start_full_bio(struct dm_snap_pending_exception *pe, + struct bio *bio) +{ + struct dm_snapshot *s = pe->snap; + void *callback_data; + + pe->full_bio = bio; + pe->full_bio_end_io = bio->bi_end_io; + pe->full_bio_private = bio->bi_private; + + callback_data = dm_kcopyd_prepare_callback(s->kcopyd_client, + copy_callback, pe); + + bio->bi_end_io = full_bio_end_io; + bio->bi_private = callback_data; + + generic_make_request(bio); +} + +static struct dm_snap_pending_exception * +__lookup_pending_exception(struct dm_snapshot *s, chunk_t chunk) +{ + struct dm_exception *e = dm_lookup_exception(&s->pending, chunk); + + if (!e) + return NULL; + + return container_of(e, struct dm_snap_pending_exception, e); } /* @@ -852,81 +1587,61 @@ static void start_copy(struct dm_snap_pending_exception *pe) * this. */ static struct dm_snap_pending_exception * -__find_pending_exception(struct dm_snapshot *s, struct bio *bio) +__find_pending_exception(struct dm_snapshot *s, + struct dm_snap_pending_exception *pe, chunk_t chunk) { - struct dm_snap_exception *e; - struct dm_snap_pending_exception *pe; - chunk_t chunk = sector_to_chunk(s, bio->bi_sector); - - /* - * Is there a pending exception for this already ? - */ - e = lookup_exception(&s->pending, chunk); - if (e) { - /* cast the exception to a pending exception */ - pe = container_of(e, struct dm_snap_pending_exception, e); - goto out; - } - - /* - * Create a new pending exception, we don't want - * to hold the lock while we do this. - */ - up_write(&s->lock); - pe = alloc_pending_exception(); - down_write(&s->lock); + struct dm_snap_pending_exception *pe2; - if (!s->valid) { + pe2 = __lookup_pending_exception(s, chunk); + if (pe2) { free_pending_exception(pe); - return NULL; - } - - e = lookup_exception(&s->pending, chunk); - if (e) { - free_pending_exception(pe); - pe = container_of(e, struct dm_snap_pending_exception, e); - goto out; + return pe2; } pe->e.old_chunk = chunk; bio_list_init(&pe->origin_bios); bio_list_init(&pe->snapshot_bios); - pe->primary_pe = NULL; - atomic_set(&pe->ref_count, 0); - pe->snap = s; pe->started = 0; + pe->full_bio = NULL; - if (s->store.prepare_exception(&s->store, &pe->e)) { + if (s->store->type->prepare_exception(s->store, &pe->e)) { free_pending_exception(pe); return NULL; } - get_pending_exception(pe); - insert_exception(&s->pending, &pe->e); + pe->exception_sequence = s->exception_start_sequence++; + + dm_insert_exception(&s->pending, &pe->e); - out: return pe; } -static void remap_exception(struct dm_snapshot *s, struct dm_snap_exception *e, +static void remap_exception(struct dm_snapshot *s, struct dm_exception *e, struct bio *bio, chunk_t chunk) { bio->bi_bdev = s->cow->bdev; - bio->bi_sector = chunk_to_sector(s, dm_chunk_number(e->new_chunk) + - (chunk - e->old_chunk)) + - (bio->bi_sector & s->chunk_mask); + bio->bi_iter.bi_sector = + chunk_to_sector(s->store, dm_chunk_number(e->new_chunk) + + (chunk - e->old_chunk)) + + (bio->bi_iter.bi_sector & s->store->chunk_mask); } -static int snapshot_map(struct dm_target *ti, struct bio *bio, - union map_info *map_context) +static int snapshot_map(struct dm_target *ti, struct bio *bio) { - struct dm_snap_exception *e; + struct dm_exception *e; struct dm_snapshot *s = ti->private; int r = DM_MAPIO_REMAPPED; chunk_t chunk; struct dm_snap_pending_exception *pe = NULL; - chunk = sector_to_chunk(s, bio->bi_sector); + init_tracked_chunk(bio); + + if (bio->bi_rw & REQ_FLUSH) { + bio->bi_bdev = s->cow->bdev; + return DM_MAPIO_REMAPPED; + } + + chunk = sector_to_chunk(s->store, bio->bi_iter.bi_sector); /* Full snapshots are not usable */ /* To get here the table must be live so s->active is always set. */ @@ -943,7 +1658,7 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio, } /* If the block is already remapped - use that, else remap it */ - e = lookup_exception(&s->complete, chunk); + e = dm_lookup_exception(&s->complete, chunk); if (e) { remap_exception(s, e, bio, chunk); goto out_unlock; @@ -955,18 +1670,48 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio, * writeable. */ if (bio_rw(bio) == WRITE) { - pe = __find_pending_exception(s, bio); + pe = __lookup_pending_exception(s, chunk); if (!pe) { - __invalidate_snapshot(s, -ENOMEM); - r = -EIO; - goto out_unlock; + up_write(&s->lock); + pe = alloc_pending_exception(s); + down_write(&s->lock); + + if (!s->valid) { + free_pending_exception(pe); + r = -EIO; + goto out_unlock; + } + + e = dm_lookup_exception(&s->complete, chunk); + if (e) { + free_pending_exception(pe); + remap_exception(s, e, bio, chunk); + goto out_unlock; + } + + pe = __find_pending_exception(s, pe, chunk); + if (!pe) { + __invalidate_snapshot(s, -ENOMEM); + r = -EIO; + goto out_unlock; + } } remap_exception(s, &pe->e, bio, chunk); - bio_list_add(&pe->snapshot_bios, bio); r = DM_MAPIO_SUBMITTED; + if (!pe->started && + bio->bi_iter.bi_size == + (s->store->chunk_size << SECTOR_SHIFT)) { + pe->started = 1; + up_write(&s->lock); + start_full_bio(pe, bio); + goto out; + } + + bio_list_add(&pe->snapshot_bios, bio); + if (!pe->started) { /* this is protected by snap->lock */ pe->started = 1; @@ -974,52 +1719,218 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio, start_copy(pe); goto out; } - } else - /* - * FIXME: this read path scares me because we - * always use the origin when we have a pending - * exception. However I can't think of a - * situation where this is wrong - ejt. - */ + } else { bio->bi_bdev = s->origin->bdev; + track_chunk(s, bio, chunk); + } + +out_unlock: + up_write(&s->lock); +out: + return r; +} + +/* + * A snapshot-merge target behaves like a combination of a snapshot + * target and a snapshot-origin target. It only generates new + * exceptions in other snapshots and not in the one that is being + * merged. + * + * For each chunk, if there is an existing exception, it is used to + * redirect I/O to the cow device. Otherwise I/O is sent to the origin, + * which in turn might generate exceptions in other snapshots. + * If merging is currently taking place on the chunk in question, the + * I/O is deferred by adding it to s->bios_queued_during_merge. + */ +static int snapshot_merge_map(struct dm_target *ti, struct bio *bio) +{ + struct dm_exception *e; + struct dm_snapshot *s = ti->private; + int r = DM_MAPIO_REMAPPED; + chunk_t chunk; + + init_tracked_chunk(bio); + + if (bio->bi_rw & REQ_FLUSH) { + if (!dm_bio_get_target_bio_nr(bio)) + bio->bi_bdev = s->origin->bdev; + else + bio->bi_bdev = s->cow->bdev; + return DM_MAPIO_REMAPPED; + } - out_unlock: + chunk = sector_to_chunk(s->store, bio->bi_iter.bi_sector); + + down_write(&s->lock); + + /* Full merging snapshots are redirected to the origin */ + if (!s->valid) + goto redirect_to_origin; + + /* If the block is already remapped - use that */ + e = dm_lookup_exception(&s->complete, chunk); + if (e) { + /* Queue writes overlapping with chunks being merged */ + if (bio_rw(bio) == WRITE && + chunk >= s->first_merging_chunk && + chunk < (s->first_merging_chunk + + s->num_merging_chunks)) { + bio->bi_bdev = s->origin->bdev; + bio_list_add(&s->bios_queued_during_merge, bio); + r = DM_MAPIO_SUBMITTED; + goto out_unlock; + } + + remap_exception(s, e, bio, chunk); + + if (bio_rw(bio) == WRITE) + track_chunk(s, bio, chunk); + goto out_unlock; + } + +redirect_to_origin: + bio->bi_bdev = s->origin->bdev; + + if (bio_rw(bio) == WRITE) { + up_write(&s->lock); + return do_origin(s->origin, bio); + } + +out_unlock: up_write(&s->lock); - out: + + return r; +} + +static int snapshot_end_io(struct dm_target *ti, struct bio *bio, int error) +{ + struct dm_snapshot *s = ti->private; + + if (is_bio_tracked(bio)) + stop_tracking_chunk(s, bio); + + return 0; +} + +static void snapshot_merge_presuspend(struct dm_target *ti) +{ + struct dm_snapshot *s = ti->private; + + stop_merge(s); +} + +static int snapshot_preresume(struct dm_target *ti) +{ + int r = 0; + struct dm_snapshot *s = ti->private; + struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; + + down_read(&_origins_lock); + (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); + if (snap_src && snap_dest) { + down_read(&snap_src->lock); + if (s == snap_src) { + DMERR("Unable to resume snapshot source until " + "handover completes."); + r = -EINVAL; + } else if (!dm_suspended(snap_src->ti)) { + DMERR("Unable to perform snapshot handover until " + "source is suspended."); + r = -EINVAL; + } + up_read(&snap_src->lock); + } + up_read(&_origins_lock); + return r; } static void snapshot_resume(struct dm_target *ti) { struct dm_snapshot *s = ti->private; + struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; + + down_read(&_origins_lock); + (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); + if (snap_src && snap_dest) { + down_write(&snap_src->lock); + down_write_nested(&snap_dest->lock, SINGLE_DEPTH_NESTING); + __handover_exceptions(snap_src, snap_dest); + up_write(&snap_dest->lock); + up_write(&snap_src->lock); + } + up_read(&_origins_lock); + + /* Now we have correct chunk size, reregister */ + reregister_snapshot(s); down_write(&s->lock); s->active = 1; up_write(&s->lock); } -static int snapshot_status(struct dm_target *ti, status_type_t type, - char *result, unsigned int maxlen) +static uint32_t get_origin_minimum_chunksize(struct block_device *bdev) { + uint32_t min_chunksize; + + down_read(&_origins_lock); + min_chunksize = __minimum_chunk_size(__lookup_origin(bdev)); + up_read(&_origins_lock); + + return min_chunksize; +} + +static void snapshot_merge_resume(struct dm_target *ti) +{ + struct dm_snapshot *s = ti->private; + + /* + * Handover exceptions from existing snapshot. + */ + snapshot_resume(ti); + + /* + * snapshot-merge acts as an origin, so set ti->max_io_len + */ + ti->max_io_len = get_origin_minimum_chunksize(s->origin->bdev); + + start_merge(s); +} + +static void snapshot_status(struct dm_target *ti, status_type_t type, + unsigned status_flags, char *result, unsigned maxlen) +{ + unsigned sz = 0; struct dm_snapshot *snap = ti->private; switch (type) { case STATUSTYPE_INFO: + + down_write(&snap->lock); + if (!snap->valid) - snprintf(result, maxlen, "Invalid"); + DMEMIT("Invalid"); + else if (snap->merge_failed) + DMEMIT("Merge failed"); else { - if (snap->store.fraction_full) { - sector_t numerator, denominator; - snap->store.fraction_full(&snap->store, - &numerator, - &denominator); - snprintf(result, maxlen, "%llu/%llu", - (unsigned long long)numerator, - (unsigned long long)denominator); + if (snap->store->type->usage) { + sector_t total_sectors, sectors_allocated, + metadata_sectors; + snap->store->type->usage(snap->store, + &total_sectors, + §ors_allocated, + &metadata_sectors); + DMEMIT("%llu/%llu %llu", + (unsigned long long)sectors_allocated, + (unsigned long long)total_sectors, + (unsigned long long)metadata_sectors); } else - snprintf(result, maxlen, "Unknown"); + DMEMIT("Unknown"); } + + up_write(&snap->lock); + break; case STATUSTYPE_TABLE: @@ -1028,30 +1939,61 @@ static int snapshot_status(struct dm_target *ti, status_type_t type, * to make private copies if the output is to * make sense. */ - snprintf(result, maxlen, "%s %s %c %llu", - snap->origin->name, snap->cow->name, - snap->type, - (unsigned long long)snap->chunk_size); + DMEMIT("%s %s", snap->origin->name, snap->cow->name); + snap->store->type->status(snap->store, type, result + sz, + maxlen - sz); break; } +} - return 0; +static int snapshot_iterate_devices(struct dm_target *ti, + iterate_devices_callout_fn fn, void *data) +{ + struct dm_snapshot *snap = ti->private; + int r; + + r = fn(ti, snap->origin, 0, ti->len, data); + + if (!r) + r = fn(ti, snap->cow, 0, get_dev_size(snap->cow->bdev), data); + + return r; } + /*----------------------------------------------------------------- * Origin methods *---------------------------------------------------------------*/ -static int __origin_write(struct list_head *snapshots, struct bio *bio) + +/* + * If no exceptions need creating, DM_MAPIO_REMAPPED is returned and any + * supplied bio was ignored. The caller may submit it immediately. + * (No remapping actually occurs as the origin is always a direct linear + * map.) + * + * If further exceptions are required, DM_MAPIO_SUBMITTED is returned + * and any supplied bio is added to a list to be submitted once all + * the necessary exceptions exist. + */ +static int __origin_write(struct list_head *snapshots, sector_t sector, + struct bio *bio) { - int r = DM_MAPIO_REMAPPED, first = 0; + int r = DM_MAPIO_REMAPPED; struct dm_snapshot *snap; - struct dm_snap_exception *e; - struct dm_snap_pending_exception *pe, *next_pe, *primary_pe = NULL; + struct dm_exception *e; + struct dm_snap_pending_exception *pe; + struct dm_snap_pending_exception *pe_to_start_now = NULL; + struct dm_snap_pending_exception *pe_to_start_last = NULL; chunk_t chunk; - LIST_HEAD(pe_queue); /* Do all the snapshots on this origin */ list_for_each_entry (snap, snapshots, list) { + /* + * Don't make new exceptions in a merging snapshot + * because it has effectively been deleted + */ + if (dm_target_is_snapshot_merge(snap->ti)) + continue; down_write(&snap->lock); @@ -1060,86 +2002,85 @@ static int __origin_write(struct list_head *snapshots, struct bio *bio) goto next_snapshot; /* Nothing to do if writing beyond end of snapshot */ - if (bio->bi_sector >= dm_table_get_size(snap->table)) + if (sector >= dm_table_get_size(snap->ti->table)) goto next_snapshot; /* * Remember, different snapshots can have * different chunk sizes. */ - chunk = sector_to_chunk(snap, bio->bi_sector); + chunk = sector_to_chunk(snap->store, sector); /* * Check exception table to see if block * is already remapped in this snapshot * and trigger an exception if not. - * - * ref_count is initialised to 1 so pending_complete() - * won't destroy the primary_pe while we're inside this loop. */ - e = lookup_exception(&snap->complete, chunk); + e = dm_lookup_exception(&snap->complete, chunk); if (e) goto next_snapshot; - pe = __find_pending_exception(snap, bio); + pe = __lookup_pending_exception(snap, chunk); if (!pe) { - __invalidate_snapshot(snap, -ENOMEM); - goto next_snapshot; - } + up_write(&snap->lock); + pe = alloc_pending_exception(snap); + down_write(&snap->lock); - if (!primary_pe) { - /* - * Either every pe here has same - * primary_pe or none has one yet. - */ - if (pe->primary_pe) - primary_pe = pe->primary_pe; - else { - primary_pe = pe; - first = 1; + if (!snap->valid) { + free_pending_exception(pe); + goto next_snapshot; } - bio_list_add(&primary_pe->origin_bios, bio); + e = dm_lookup_exception(&snap->complete, chunk); + if (e) { + free_pending_exception(pe); + goto next_snapshot; + } - r = DM_MAPIO_SUBMITTED; + pe = __find_pending_exception(snap, pe, chunk); + if (!pe) { + __invalidate_snapshot(snap, -ENOMEM); + goto next_snapshot; + } } - if (!pe->primary_pe) { - pe->primary_pe = primary_pe; - get_pending_exception(primary_pe); + r = DM_MAPIO_SUBMITTED; + + /* + * If an origin bio was supplied, queue it to wait for the + * completion of this exception, and start this one last, + * at the end of the function. + */ + if (bio) { + bio_list_add(&pe->origin_bios, bio); + bio = NULL; + + if (!pe->started) { + pe->started = 1; + pe_to_start_last = pe; + } } if (!pe->started) { pe->started = 1; - list_add_tail(&pe->list, &pe_queue); + pe_to_start_now = pe; } - next_snapshot: +next_snapshot: up_write(&snap->lock); - } - - if (!primary_pe) - return r; - - /* - * If this is the first time we're processing this chunk and - * ref_count is now 1 it means all the pending exceptions - * got completed while we were in the loop above, so it falls to - * us here to remove the primary_pe and submit any origin_bios. - */ - if (first && atomic_dec_and_test(&primary_pe->ref_count)) { - flush_bios(bio_list_get(&primary_pe->origin_bios)); - free_pending_exception(primary_pe); - /* If we got here, pe_queue is necessarily empty. */ - return r; + if (pe_to_start_now) { + start_copy(pe_to_start_now); + pe_to_start_now = NULL; + } } /* - * Now that we have a complete pe list we can start the copying. + * Submit the exception against which the bio is queued last, + * to give the other exceptions a head start. */ - list_for_each_entry_safe(pe, next_pe, &pe_queue, list) - start_copy(pe); + if (pe_to_start_last) + start_copy(pe_to_start_last); return r; } @@ -1155,16 +2096,56 @@ static int do_origin(struct dm_dev *origin, struct bio *bio) down_read(&_origins_lock); o = __lookup_origin(origin->bdev); if (o) - r = __origin_write(&o->snapshots, bio); + r = __origin_write(&o->snapshots, bio->bi_iter.bi_sector, bio); up_read(&_origins_lock); return r; } /* + * Trigger exceptions in all non-merging snapshots. + * + * The chunk size of the merging snapshot may be larger than the chunk + * size of some other snapshot so we may need to reallocate multiple + * chunks in other snapshots. + * + * We scan all the overlapping exceptions in the other snapshots. + * Returns 1 if anything was reallocated and must be waited for, + * otherwise returns 0. + * + * size must be a multiple of merging_snap's chunk_size. + */ +static int origin_write_extent(struct dm_snapshot *merging_snap, + sector_t sector, unsigned size) +{ + int must_wait = 0; + sector_t n; + struct origin *o; + + /* + * The origin's __minimum_chunk_size() got stored in max_io_len + * by snapshot_merge_resume(). + */ + down_read(&_origins_lock); + o = __lookup_origin(merging_snap->origin->bdev); + for (n = 0; n < size; n += merging_snap->ti->max_io_len) + if (__origin_write(&o->snapshots, sector + n, NULL) == + DM_MAPIO_SUBMITTED) + must_wait = 1; + up_read(&_origins_lock); + + return must_wait; +} + +/* * Origin: maps a linear range of a device, with hooks for snapshotting. */ +struct dm_origin { + struct dm_dev *dev; + unsigned split_boundary; +}; + /* * Construct an origin mapping: <dev_path> * The context for an origin is merely a 'struct dm_dev *' @@ -1173,67 +2154,82 @@ static int do_origin(struct dm_dev *origin, struct bio *bio) static int origin_ctr(struct dm_target *ti, unsigned int argc, char **argv) { int r; - struct dm_dev *dev; + struct dm_origin *o; if (argc != 1) { ti->error = "origin: incorrect number of arguments"; return -EINVAL; } - r = dm_get_device(ti, argv[0], 0, ti->len, - dm_table_get_mode(ti->table), &dev); + o = kmalloc(sizeof(struct dm_origin), GFP_KERNEL); + if (!o) { + ti->error = "Cannot allocate private origin structure"; + r = -ENOMEM; + goto bad_alloc; + } + + r = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &o->dev); if (r) { ti->error = "Cannot get target device"; - return r; + goto bad_open; } - ti->private = dev; + ti->private = o; + ti->num_flush_bios = 1; + return 0; + +bad_open: + kfree(o); +bad_alloc: + return r; } static void origin_dtr(struct dm_target *ti) { - struct dm_dev *dev = ti->private; - dm_put_device(ti, dev); + struct dm_origin *o = ti->private; + dm_put_device(ti, o->dev); + kfree(o); } -static int origin_map(struct dm_target *ti, struct bio *bio, - union map_info *map_context) +static int origin_map(struct dm_target *ti, struct bio *bio) { - struct dm_dev *dev = ti->private; - bio->bi_bdev = dev->bdev; + struct dm_origin *o = ti->private; + unsigned available_sectors; + + bio->bi_bdev = o->dev->bdev; + + if (unlikely(bio->bi_rw & REQ_FLUSH)) + return DM_MAPIO_REMAPPED; + + if (bio_rw(bio) != WRITE) + return DM_MAPIO_REMAPPED; + + available_sectors = o->split_boundary - + ((unsigned)bio->bi_iter.bi_sector & (o->split_boundary - 1)); + + if (bio_sectors(bio) > available_sectors) + dm_accept_partial_bio(bio, available_sectors); /* Only tell snapshots if this is a write */ - return (bio_rw(bio) == WRITE) ? do_origin(dev, bio) : DM_MAPIO_REMAPPED; + return do_origin(o->dev, bio); } -#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r)) - /* - * Set the target "split_io" field to the minimum of all the snapshots' + * Set the target "max_io_len" field to the minimum of all the snapshots' * chunk sizes. */ static void origin_resume(struct dm_target *ti) { - struct dm_dev *dev = ti->private; - struct dm_snapshot *snap; - struct origin *o; - chunk_t chunk_size = 0; + struct dm_origin *o = ti->private; - down_read(&_origins_lock); - o = __lookup_origin(dev->bdev); - if (o) - list_for_each_entry (snap, &o->snapshots, list) - chunk_size = min_not_zero(chunk_size, snap->chunk_size); - up_read(&_origins_lock); - - ti->split_io = chunk_size; + o->split_boundary = get_origin_minimum_chunksize(o->dev->bdev); } -static int origin_status(struct dm_target *ti, status_type_t type, char *result, - unsigned int maxlen) +static void origin_status(struct dm_target *ti, status_type_t type, + unsigned status_flags, char *result, unsigned maxlen) { - struct dm_dev *dev = ti->private; + struct dm_origin *o = ti->private; switch (type) { case STATUSTYPE_INFO: @@ -1241,120 +2237,152 @@ static int origin_status(struct dm_target *ti, status_type_t type, char *result, break; case STATUSTYPE_TABLE: - snprintf(result, maxlen, "%s", dev->name); + snprintf(result, maxlen, "%s", o->dev->name); break; } +} - return 0; +static int origin_merge(struct dm_target *ti, struct bvec_merge_data *bvm, + struct bio_vec *biovec, int max_size) +{ + struct dm_origin *o = ti->private; + struct request_queue *q = bdev_get_queue(o->dev->bdev); + + if (!q->merge_bvec_fn) + return max_size; + + bvm->bi_bdev = o->dev->bdev; + + return min(max_size, q->merge_bvec_fn(q, bvm, biovec)); +} + +static int origin_iterate_devices(struct dm_target *ti, + iterate_devices_callout_fn fn, void *data) +{ + struct dm_origin *o = ti->private; + + return fn(ti, o->dev, 0, ti->len, data); } static struct target_type origin_target = { .name = "snapshot-origin", - .version = {1, 6, 0}, + .version = {1, 8, 1}, .module = THIS_MODULE, .ctr = origin_ctr, .dtr = origin_dtr, .map = origin_map, .resume = origin_resume, .status = origin_status, + .merge = origin_merge, + .iterate_devices = origin_iterate_devices, }; static struct target_type snapshot_target = { .name = "snapshot", - .version = {1, 6, 0}, + .version = {1, 12, 0}, .module = THIS_MODULE, .ctr = snapshot_ctr, .dtr = snapshot_dtr, .map = snapshot_map, + .end_io = snapshot_end_io, + .preresume = snapshot_preresume, .resume = snapshot_resume, .status = snapshot_status, + .iterate_devices = snapshot_iterate_devices, +}; + +static struct target_type merge_target = { + .name = dm_snapshot_merge_target_name, + .version = {1, 2, 0}, + .module = THIS_MODULE, + .ctr = snapshot_ctr, + .dtr = snapshot_dtr, + .map = snapshot_merge_map, + .end_io = snapshot_end_io, + .presuspend = snapshot_merge_presuspend, + .preresume = snapshot_preresume, + .resume = snapshot_merge_resume, + .status = snapshot_status, + .iterate_devices = snapshot_iterate_devices, }; static int __init dm_snapshot_init(void) { int r; - r = dm_register_target(&snapshot_target); + r = dm_exception_store_init(); if (r) { - DMERR("snapshot target register failed %d", r); + DMERR("Failed to initialize exception stores"); return r; } + r = dm_register_target(&snapshot_target); + if (r < 0) { + DMERR("snapshot target register failed %d", r); + goto bad_register_snapshot_target; + } + r = dm_register_target(&origin_target); if (r < 0) { DMERR("Origin target register failed %d", r); - goto bad1; + goto bad_register_origin_target; + } + + r = dm_register_target(&merge_target); + if (r < 0) { + DMERR("Merge target register failed %d", r); + goto bad_register_merge_target; } r = init_origin_hash(); if (r) { DMERR("init_origin_hash failed."); - goto bad2; + goto bad_origin_hash; } - exception_cache = KMEM_CACHE(dm_snap_exception, 0); + exception_cache = KMEM_CACHE(dm_exception, 0); if (!exception_cache) { DMERR("Couldn't create exception cache."); r = -ENOMEM; - goto bad3; + goto bad_exception_cache; } pending_cache = KMEM_CACHE(dm_snap_pending_exception, 0); if (!pending_cache) { DMERR("Couldn't create pending cache."); r = -ENOMEM; - goto bad4; - } - - pending_pool = mempool_create_slab_pool(128, pending_cache); - if (!pending_pool) { - DMERR("Couldn't create pending pool."); - r = -ENOMEM; - goto bad5; - } - - ksnapd = create_singlethread_workqueue("ksnapd"); - if (!ksnapd) { - DMERR("Failed to create ksnapd workqueue."); - r = -ENOMEM; - goto bad6; + goto bad_pending_cache; } return 0; - bad6: - mempool_destroy(pending_pool); - bad5: - kmem_cache_destroy(pending_cache); - bad4: +bad_pending_cache: kmem_cache_destroy(exception_cache); - bad3: +bad_exception_cache: exit_origin_hash(); - bad2: +bad_origin_hash: + dm_unregister_target(&merge_target); +bad_register_merge_target: dm_unregister_target(&origin_target); - bad1: +bad_register_origin_target: dm_unregister_target(&snapshot_target); +bad_register_snapshot_target: + dm_exception_store_exit(); + return r; } static void __exit dm_snapshot_exit(void) { - int r; - - destroy_workqueue(ksnapd); - - r = dm_unregister_target(&snapshot_target); - if (r) - DMERR("snapshot unregister failed %d", r); - - r = dm_unregister_target(&origin_target); - if (r) - DMERR("origin unregister failed %d", r); + dm_unregister_target(&snapshot_target); + dm_unregister_target(&origin_target); + dm_unregister_target(&merge_target); exit_origin_hash(); - mempool_destroy(pending_pool); kmem_cache_destroy(pending_cache); kmem_cache_destroy(exception_cache); + + dm_exception_store_exit(); } /* Module hooks */ @@ -1364,3 +2392,5 @@ module_exit(dm_snapshot_exit); MODULE_DESCRIPTION(DM_NAME " snapshot target"); MODULE_AUTHOR("Joe Thornber"); MODULE_LICENSE("GPL"); +MODULE_ALIAS("dm-snapshot-origin"); +MODULE_ALIAS("dm-snapshot-merge"); |