11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * Copyright (C) 2001-2002 Sistina Software (UK) Limited. 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * This file is released under the GPL. 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds #include <linux/blkdev.h> 81da177e4SLinus Torvalds #include <linux/device-mapper.h> 990fa1527SMikulas Patocka #include <linux/delay.h> 101da177e4SLinus Torvalds #include <linux/fs.h> 111da177e4SLinus Torvalds #include <linux/init.h> 121da177e4SLinus Torvalds #include <linux/kdev_t.h> 131da177e4SLinus Torvalds #include <linux/list.h> 14f79ae415SNikos Tsironis #include <linux/list_bl.h> 151da177e4SLinus Torvalds #include <linux/mempool.h> 161da177e4SLinus Torvalds #include <linux/module.h> 171da177e4SLinus Torvalds #include <linux/slab.h> 181da177e4SLinus Torvalds #include <linux/vmalloc.h> 196f3c3f0aSvignesh babu #include <linux/log2.h> 20a765e20eSAlasdair G Kergon #include <linux/dm-kcopyd.h> 211da177e4SLinus Torvalds 22b735fedeSMikulas Patocka #include "dm.h" 23b735fedeSMikulas Patocka 24aea53d92SJonathan Brassow #include "dm-exception-store.h" 251da177e4SLinus Torvalds 2672d94861SAlasdair G Kergon #define DM_MSG_PREFIX "snapshots" 2772d94861SAlasdair G Kergon 28d698aa45SMikulas Patocka static const char dm_snapshot_merge_target_name[] = "snapshot-merge"; 29d698aa45SMikulas Patocka 30d698aa45SMikulas Patocka #define dm_target_is_snapshot_merge(ti) \ 31d698aa45SMikulas Patocka ((ti)->type->name == dm_snapshot_merge_target_name) 32d698aa45SMikulas Patocka 331da177e4SLinus Torvalds /* 34cd45daffSMikulas Patocka * The size of the mempool used to track chunks in use. 35cd45daffSMikulas Patocka */ 36cd45daffSMikulas Patocka #define MIN_IOS 256 37cd45daffSMikulas Patocka 38ccc45ea8SJonathan Brassow #define DM_TRACKED_CHUNK_HASH_SIZE 16 39ccc45ea8SJonathan Brassow #define DM_TRACKED_CHUNK_HASH(x) ((unsigned long)(x) & \ 40ccc45ea8SJonathan Brassow (DM_TRACKED_CHUNK_HASH_SIZE - 1)) 41ccc45ea8SJonathan Brassow 42191437a5SJon Brassow struct dm_exception_table { 43ccc45ea8SJonathan Brassow uint32_t hash_mask; 44ccc45ea8SJonathan Brassow unsigned hash_shift; 45f79ae415SNikos Tsironis struct hlist_bl_head *table; 46ccc45ea8SJonathan Brassow }; 47ccc45ea8SJonathan Brassow 48ccc45ea8SJonathan Brassow struct dm_snapshot { 494ad8d880SNikos Tsironis struct rw_semaphore lock; 50ccc45ea8SJonathan Brassow 51ccc45ea8SJonathan Brassow struct dm_dev *origin; 52fc56f6fbSMike Snitzer struct dm_dev *cow; 53fc56f6fbSMike Snitzer 54fc56f6fbSMike Snitzer struct dm_target *ti; 55ccc45ea8SJonathan Brassow 56ccc45ea8SJonathan Brassow /* List of snapshots per Origin */ 57ccc45ea8SJonathan Brassow struct list_head list; 58ccc45ea8SJonathan Brassow 59d8ddb1cfSMike Snitzer /* 60d8ddb1cfSMike Snitzer * You can't use a snapshot if this is 0 (e.g. if full). 61d8ddb1cfSMike Snitzer * A snapshot-merge target never clears this. 62d8ddb1cfSMike Snitzer */ 63ccc45ea8SJonathan Brassow int valid; 64ccc45ea8SJonathan Brassow 6576c44f6dSMikulas Patocka /* 6676c44f6dSMikulas Patocka * The snapshot overflowed because of a write to the snapshot device. 6776c44f6dSMikulas Patocka * We don't have to invalidate the snapshot in this case, but we need 6876c44f6dSMikulas Patocka * to prevent further writes. 6976c44f6dSMikulas Patocka */ 7076c44f6dSMikulas Patocka int snapshot_overflowed; 7176c44f6dSMikulas Patocka 72ccc45ea8SJonathan Brassow /* Origin writes don't trigger exceptions until this is set */ 73ccc45ea8SJonathan Brassow int active; 74ccc45ea8SJonathan Brassow 75ccc45ea8SJonathan Brassow atomic_t pending_exceptions_count; 76ccc45ea8SJonathan Brassow 773f1637f2SNikos Tsironis spinlock_t pe_allocation_lock; 783f1637f2SNikos Tsironis 793f1637f2SNikos Tsironis /* Protected by "pe_allocation_lock" */ 80230c83afSMikulas Patocka sector_t exception_start_sequence; 81230c83afSMikulas Patocka 82230c83afSMikulas Patocka /* Protected by kcopyd single-threaded callback */ 83230c83afSMikulas Patocka sector_t exception_complete_sequence; 84230c83afSMikulas Patocka 85230c83afSMikulas Patocka /* 86230c83afSMikulas Patocka * A list of pending exceptions that completed out of order. 87230c83afSMikulas Patocka * Protected by kcopyd single-threaded callback. 88230c83afSMikulas Patocka */ 893db2776dSDavid Jeffery struct rb_root out_of_order_tree; 90230c83afSMikulas Patocka 916f1c819cSKent Overstreet mempool_t pending_pool; 92924e600dSMike Snitzer 93191437a5SJon Brassow struct dm_exception_table pending; 94191437a5SJon Brassow struct dm_exception_table complete; 95ccc45ea8SJonathan Brassow 96ccc45ea8SJonathan Brassow /* 97ccc45ea8SJonathan Brassow * pe_lock protects all pending_exception operations and access 98ccc45ea8SJonathan Brassow * as well as the snapshot_bios list. 99ccc45ea8SJonathan Brassow */ 100ccc45ea8SJonathan Brassow spinlock_t pe_lock; 101ccc45ea8SJonathan Brassow 102924e600dSMike Snitzer /* Chunks with outstanding reads */ 103924e600dSMike Snitzer spinlock_t tracked_chunk_lock; 104924e600dSMike Snitzer struct hlist_head tracked_chunk_hash[DM_TRACKED_CHUNK_HASH_SIZE]; 105924e600dSMike Snitzer 106ccc45ea8SJonathan Brassow /* The on disk metadata handler */ 107ccc45ea8SJonathan Brassow struct dm_exception_store *store; 108ccc45ea8SJonathan Brassow 109b2155578SMikulas Patocka unsigned in_progress; 110b2155578SMikulas Patocka struct wait_queue_head in_progress_wait; 111721b1d98SNikos Tsironis 112ccc45ea8SJonathan Brassow struct dm_kcopyd_client *kcopyd_client; 113ccc45ea8SJonathan Brassow 114924e600dSMike Snitzer /* Wait for events based on state_bits */ 115924e600dSMike Snitzer unsigned long state_bits; 116924e600dSMike Snitzer 117924e600dSMike Snitzer /* Range of chunks currently being merged. */ 118924e600dSMike Snitzer chunk_t first_merging_chunk; 119924e600dSMike Snitzer int num_merging_chunks; 1201e03f97eSMikulas Patocka 121d8ddb1cfSMike Snitzer /* 122d8ddb1cfSMike Snitzer * The merge operation failed if this flag is set. 123d8ddb1cfSMike Snitzer * Failure modes are handled as follows: 124d8ddb1cfSMike Snitzer * - I/O error reading the header 125d8ddb1cfSMike Snitzer * => don't load the target; abort. 126d8ddb1cfSMike Snitzer * - Header does not have "valid" flag set 127d8ddb1cfSMike Snitzer * => use the origin; forget about the snapshot. 128d8ddb1cfSMike Snitzer * - I/O error when reading exceptions 129d8ddb1cfSMike Snitzer * => don't load the target; abort. 130d8ddb1cfSMike Snitzer * (We can't use the intermediate origin state.) 131d8ddb1cfSMike Snitzer * - I/O error while merging 132d8ddb1cfSMike Snitzer * => stop merging; set merge_failed; process I/O normally. 133d8ddb1cfSMike Snitzer */ 1342e602385SMike Snitzer bool merge_failed:1; 1352e602385SMike Snitzer 1362e602385SMike Snitzer bool discard_zeroes_cow:1; 1372e602385SMike Snitzer bool discard_passdown_origin:1; 138d8ddb1cfSMike Snitzer 1399fe86254SMikulas Patocka /* 1409fe86254SMikulas Patocka * Incoming bios that overlap with chunks being merged must wait 1419fe86254SMikulas Patocka * for them to be committed. 1429fe86254SMikulas Patocka */ 1439fe86254SMikulas Patocka struct bio_list bios_queued_during_merge; 144fcc42338SAkilesh Kailash 145fcc42338SAkilesh Kailash /* 146fcc42338SAkilesh Kailash * Flush data after merge. 147fcc42338SAkilesh Kailash */ 148fcc42338SAkilesh Kailash struct bio flush_bio; 149ccc45ea8SJonathan Brassow }; 150ccc45ea8SJonathan Brassow 1511e03f97eSMikulas Patocka /* 1521e03f97eSMikulas Patocka * state_bits: 1531e03f97eSMikulas Patocka * RUNNING_MERGE - Merge operation is in progress. 1541e03f97eSMikulas Patocka * SHUTDOWN_MERGE - Set to signal that merge needs to be stopped; 1551e03f97eSMikulas Patocka * cleared afterwards. 1561e03f97eSMikulas Patocka */ 1571e03f97eSMikulas Patocka #define RUNNING_MERGE 0 1581e03f97eSMikulas Patocka #define SHUTDOWN_MERGE 1 1591e03f97eSMikulas Patocka 160721b1d98SNikos Tsironis /* 161721b1d98SNikos Tsironis * Maximum number of chunks being copied on write. 162721b1d98SNikos Tsironis * 163721b1d98SNikos Tsironis * The value was decided experimentally as a trade-off between memory 164721b1d98SNikos Tsironis * consumption, stalling the kernel's workqueues and maintaining a high enough 165721b1d98SNikos Tsironis * throughput. 166721b1d98SNikos Tsironis */ 167721b1d98SNikos Tsironis #define DEFAULT_COW_THRESHOLD 2048 168721b1d98SNikos Tsironis 169b2155578SMikulas Patocka static unsigned cow_threshold = DEFAULT_COW_THRESHOLD; 170b2155578SMikulas Patocka module_param_named(snapshot_cow_threshold, cow_threshold, uint, 0644); 171721b1d98SNikos Tsironis MODULE_PARM_DESC(snapshot_cow_threshold, "Maximum number of chunks being copied on write"); 172721b1d98SNikos Tsironis 173df5d2e90SMikulas Patocka DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(snapshot_copy_throttle, 174df5d2e90SMikulas Patocka "A percentage of time allocated for copy on write"); 175df5d2e90SMikulas Patocka 176c2411045SMikulas Patocka struct dm_dev *dm_snap_origin(struct dm_snapshot *s) 177c2411045SMikulas Patocka { 178c2411045SMikulas Patocka return s->origin; 179c2411045SMikulas Patocka } 180c2411045SMikulas Patocka EXPORT_SYMBOL(dm_snap_origin); 181c2411045SMikulas Patocka 182fc56f6fbSMike Snitzer struct dm_dev *dm_snap_cow(struct dm_snapshot *s) 183fc56f6fbSMike Snitzer { 184fc56f6fbSMike Snitzer return s->cow; 185fc56f6fbSMike Snitzer } 186fc56f6fbSMike Snitzer EXPORT_SYMBOL(dm_snap_cow); 187fc56f6fbSMike Snitzer 188ccc45ea8SJonathan Brassow static sector_t chunk_to_sector(struct dm_exception_store *store, 189ccc45ea8SJonathan Brassow chunk_t chunk) 190ccc45ea8SJonathan Brassow { 191ccc45ea8SJonathan Brassow return chunk << store->chunk_shift; 192ccc45ea8SJonathan Brassow } 193ccc45ea8SJonathan Brassow 194ccc45ea8SJonathan Brassow static int bdev_equal(struct block_device *lhs, struct block_device *rhs) 195ccc45ea8SJonathan Brassow { 196ccc45ea8SJonathan Brassow /* 197ccc45ea8SJonathan Brassow * There is only ever one instance of a particular block 198ccc45ea8SJonathan Brassow * device so we can compare pointers safely. 199ccc45ea8SJonathan Brassow */ 200ccc45ea8SJonathan Brassow return lhs == rhs; 201ccc45ea8SJonathan Brassow } 202ccc45ea8SJonathan Brassow 203028867acSAlasdair G Kergon struct dm_snap_pending_exception { 2041d4989c8SJon Brassow struct dm_exception e; 2051da177e4SLinus Torvalds 2061da177e4SLinus Torvalds /* 2071da177e4SLinus Torvalds * Origin buffers waiting for this to complete are held 2081da177e4SLinus Torvalds * in a bio list 2091da177e4SLinus Torvalds */ 2101da177e4SLinus Torvalds struct bio_list origin_bios; 2111da177e4SLinus Torvalds struct bio_list snapshot_bios; 2121da177e4SLinus Torvalds 2131da177e4SLinus Torvalds /* Pointer back to snapshot context */ 2141da177e4SLinus Torvalds struct dm_snapshot *snap; 2151da177e4SLinus Torvalds 2161da177e4SLinus Torvalds /* 2171da177e4SLinus Torvalds * 1 indicates the exception has already been sent to 2181da177e4SLinus Torvalds * kcopyd. 2191da177e4SLinus Torvalds */ 2201da177e4SLinus Torvalds int started; 221a6e50b40SMikulas Patocka 222230c83afSMikulas Patocka /* There was copying error. */ 223230c83afSMikulas Patocka int copy_error; 224230c83afSMikulas Patocka 225230c83afSMikulas Patocka /* A sequence number, it is used for in-order completion. */ 226230c83afSMikulas Patocka sector_t exception_sequence; 227230c83afSMikulas Patocka 2283db2776dSDavid Jeffery struct rb_node out_of_order_node; 229230c83afSMikulas Patocka 230a6e50b40SMikulas Patocka /* 231a6e50b40SMikulas Patocka * For writing a complete chunk, bypassing the copy. 232a6e50b40SMikulas Patocka */ 233a6e50b40SMikulas Patocka struct bio *full_bio; 234a6e50b40SMikulas Patocka bio_end_io_t *full_bio_end_io; 2351da177e4SLinus Torvalds }; 2361da177e4SLinus Torvalds 2371da177e4SLinus Torvalds /* 2381da177e4SLinus Torvalds * Hash table mapping origin volumes to lists of snapshots and 2391da177e4SLinus Torvalds * a lock to protect it 2401da177e4SLinus Torvalds */ 241e18b890bSChristoph Lameter static struct kmem_cache *exception_cache; 242e18b890bSChristoph Lameter static struct kmem_cache *pending_cache; 2431da177e4SLinus Torvalds 244cd45daffSMikulas Patocka struct dm_snap_tracked_chunk { 245cd45daffSMikulas Patocka struct hlist_node node; 246cd45daffSMikulas Patocka chunk_t chunk; 247cd45daffSMikulas Patocka }; 248cd45daffSMikulas Patocka 249ee18026aSMikulas Patocka static void init_tracked_chunk(struct bio *bio) 250ee18026aSMikulas Patocka { 251ee18026aSMikulas Patocka struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk)); 252ee18026aSMikulas Patocka INIT_HLIST_NODE(&c->node); 253ee18026aSMikulas Patocka } 254ee18026aSMikulas Patocka 255ee18026aSMikulas Patocka static bool is_bio_tracked(struct bio *bio) 256ee18026aSMikulas Patocka { 257ee18026aSMikulas Patocka struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk)); 258ee18026aSMikulas Patocka return !hlist_unhashed(&c->node); 259ee18026aSMikulas Patocka } 260ee18026aSMikulas Patocka 261ee18026aSMikulas Patocka static void track_chunk(struct dm_snapshot *s, struct bio *bio, chunk_t chunk) 262cd45daffSMikulas Patocka { 26342bc954fSMikulas Patocka struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk)); 264cd45daffSMikulas Patocka 265cd45daffSMikulas Patocka c->chunk = chunk; 266cd45daffSMikulas Patocka 2679aa0c0e6SMikulas Patocka spin_lock_irq(&s->tracked_chunk_lock); 268cd45daffSMikulas Patocka hlist_add_head(&c->node, 269cd45daffSMikulas Patocka &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)]); 2709aa0c0e6SMikulas Patocka spin_unlock_irq(&s->tracked_chunk_lock); 271cd45daffSMikulas Patocka } 272cd45daffSMikulas Patocka 273ee18026aSMikulas Patocka static void stop_tracking_chunk(struct dm_snapshot *s, struct bio *bio) 274cd45daffSMikulas Patocka { 275ee18026aSMikulas Patocka struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk)); 276cd45daffSMikulas Patocka unsigned long flags; 277cd45daffSMikulas Patocka 278cd45daffSMikulas Patocka spin_lock_irqsave(&s->tracked_chunk_lock, flags); 279cd45daffSMikulas Patocka hlist_del(&c->node); 280cd45daffSMikulas Patocka spin_unlock_irqrestore(&s->tracked_chunk_lock, flags); 281cd45daffSMikulas Patocka } 282cd45daffSMikulas Patocka 283a8d41b59SMikulas Patocka static int __chunk_is_tracked(struct dm_snapshot *s, chunk_t chunk) 284a8d41b59SMikulas Patocka { 285a8d41b59SMikulas Patocka struct dm_snap_tracked_chunk *c; 286a8d41b59SMikulas Patocka int found = 0; 287a8d41b59SMikulas Patocka 288a8d41b59SMikulas Patocka spin_lock_irq(&s->tracked_chunk_lock); 289a8d41b59SMikulas Patocka 290b67bfe0dSSasha Levin hlist_for_each_entry(c, 291a8d41b59SMikulas Patocka &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)], node) { 292a8d41b59SMikulas Patocka if (c->chunk == chunk) { 293a8d41b59SMikulas Patocka found = 1; 294a8d41b59SMikulas Patocka break; 295a8d41b59SMikulas Patocka } 296a8d41b59SMikulas Patocka } 297a8d41b59SMikulas Patocka 298a8d41b59SMikulas Patocka spin_unlock_irq(&s->tracked_chunk_lock); 299a8d41b59SMikulas Patocka 300a8d41b59SMikulas Patocka return found; 301a8d41b59SMikulas Patocka } 302a8d41b59SMikulas Patocka 3031da177e4SLinus Torvalds /* 304615d1eb9SMike Snitzer * This conflicting I/O is extremely improbable in the caller, 305615d1eb9SMike Snitzer * so msleep(1) is sufficient and there is no need for a wait queue. 306615d1eb9SMike Snitzer */ 307615d1eb9SMike Snitzer static void __check_for_conflicting_io(struct dm_snapshot *s, chunk_t chunk) 308615d1eb9SMike Snitzer { 309615d1eb9SMike Snitzer while (__chunk_is_tracked(s, chunk)) 310615d1eb9SMike Snitzer msleep(1); 311615d1eb9SMike Snitzer } 312615d1eb9SMike Snitzer 313615d1eb9SMike Snitzer /* 3141da177e4SLinus Torvalds * One of these per registered origin, held in the snapshot_origins hash 3151da177e4SLinus Torvalds */ 3161da177e4SLinus Torvalds struct origin { 3171da177e4SLinus Torvalds /* The origin device */ 3181da177e4SLinus Torvalds struct block_device *bdev; 3191da177e4SLinus Torvalds 3201da177e4SLinus Torvalds struct list_head hash_list; 3211da177e4SLinus Torvalds 3221da177e4SLinus Torvalds /* List of snapshots for this origin */ 3231da177e4SLinus Torvalds struct list_head snapshots; 3241da177e4SLinus Torvalds }; 3251da177e4SLinus Torvalds 3261da177e4SLinus Torvalds /* 327b735fedeSMikulas Patocka * This structure is allocated for each origin target 328b735fedeSMikulas Patocka */ 329b735fedeSMikulas Patocka struct dm_origin { 330b735fedeSMikulas Patocka struct dm_dev *dev; 331b735fedeSMikulas Patocka struct dm_target *ti; 332b735fedeSMikulas Patocka unsigned split_boundary; 333b735fedeSMikulas Patocka struct list_head hash_list; 334b735fedeSMikulas Patocka }; 335b735fedeSMikulas Patocka 336b735fedeSMikulas Patocka /* 3371da177e4SLinus Torvalds * Size of the hash table for origin volumes. If we make this 3381da177e4SLinus Torvalds * the size of the minors list then it should be nearly perfect 3391da177e4SLinus Torvalds */ 3401da177e4SLinus Torvalds #define ORIGIN_HASH_SIZE 256 3411da177e4SLinus Torvalds #define ORIGIN_MASK 0xFF 3421da177e4SLinus Torvalds static struct list_head *_origins; 343b735fedeSMikulas Patocka static struct list_head *_dm_origins; 3441da177e4SLinus Torvalds static struct rw_semaphore _origins_lock; 3451da177e4SLinus Torvalds 34673dfd078SMikulas Patocka static DECLARE_WAIT_QUEUE_HEAD(_pending_exceptions_done); 34773dfd078SMikulas Patocka static DEFINE_SPINLOCK(_pending_exceptions_done_spinlock); 34873dfd078SMikulas Patocka static uint64_t _pending_exceptions_done_count; 34973dfd078SMikulas Patocka 3501da177e4SLinus Torvalds static int init_origin_hash(void) 3511da177e4SLinus Torvalds { 3521da177e4SLinus Torvalds int i; 3531da177e4SLinus Torvalds 3546da2ec56SKees Cook _origins = kmalloc_array(ORIGIN_HASH_SIZE, sizeof(struct list_head), 3551da177e4SLinus Torvalds GFP_KERNEL); 3561da177e4SLinus Torvalds if (!_origins) { 357b735fedeSMikulas Patocka DMERR("unable to allocate memory for _origins"); 3581da177e4SLinus Torvalds return -ENOMEM; 3591da177e4SLinus Torvalds } 3601da177e4SLinus Torvalds for (i = 0; i < ORIGIN_HASH_SIZE; i++) 3611da177e4SLinus Torvalds INIT_LIST_HEAD(_origins + i); 362b735fedeSMikulas Patocka 3636da2ec56SKees Cook _dm_origins = kmalloc_array(ORIGIN_HASH_SIZE, 3646da2ec56SKees Cook sizeof(struct list_head), 365b735fedeSMikulas Patocka GFP_KERNEL); 366b735fedeSMikulas Patocka if (!_dm_origins) { 367b735fedeSMikulas Patocka DMERR("unable to allocate memory for _dm_origins"); 368b735fedeSMikulas Patocka kfree(_origins); 369b735fedeSMikulas Patocka return -ENOMEM; 370b735fedeSMikulas Patocka } 371b735fedeSMikulas Patocka for (i = 0; i < ORIGIN_HASH_SIZE; i++) 372b735fedeSMikulas Patocka INIT_LIST_HEAD(_dm_origins + i); 373b735fedeSMikulas Patocka 3741da177e4SLinus Torvalds init_rwsem(&_origins_lock); 3751da177e4SLinus Torvalds 3761da177e4SLinus Torvalds return 0; 3771da177e4SLinus Torvalds } 3781da177e4SLinus Torvalds 3791da177e4SLinus Torvalds static void exit_origin_hash(void) 3801da177e4SLinus Torvalds { 3811da177e4SLinus Torvalds kfree(_origins); 382b735fedeSMikulas Patocka kfree(_dm_origins); 3831da177e4SLinus Torvalds } 3841da177e4SLinus Torvalds 385028867acSAlasdair G Kergon static unsigned origin_hash(struct block_device *bdev) 3861da177e4SLinus Torvalds { 3871da177e4SLinus Torvalds return bdev->bd_dev & ORIGIN_MASK; 3881da177e4SLinus Torvalds } 3891da177e4SLinus Torvalds 3901da177e4SLinus Torvalds static struct origin *__lookup_origin(struct block_device *origin) 3911da177e4SLinus Torvalds { 3921da177e4SLinus Torvalds struct list_head *ol; 3931da177e4SLinus Torvalds struct origin *o; 3941da177e4SLinus Torvalds 3951da177e4SLinus Torvalds ol = &_origins[origin_hash(origin)]; 3961da177e4SLinus Torvalds list_for_each_entry (o, ol, hash_list) 3971da177e4SLinus Torvalds if (bdev_equal(o->bdev, origin)) 3981da177e4SLinus Torvalds return o; 3991da177e4SLinus Torvalds 4001da177e4SLinus Torvalds return NULL; 4011da177e4SLinus Torvalds } 4021da177e4SLinus Torvalds 4031da177e4SLinus Torvalds static void __insert_origin(struct origin *o) 4041da177e4SLinus Torvalds { 4051da177e4SLinus Torvalds struct list_head *sl = &_origins[origin_hash(o->bdev)]; 4061da177e4SLinus Torvalds list_add_tail(&o->hash_list, sl); 4071da177e4SLinus Torvalds } 4081da177e4SLinus Torvalds 409b735fedeSMikulas Patocka static struct dm_origin *__lookup_dm_origin(struct block_device *origin) 410b735fedeSMikulas Patocka { 411b735fedeSMikulas Patocka struct list_head *ol; 412b735fedeSMikulas Patocka struct dm_origin *o; 413b735fedeSMikulas Patocka 414b735fedeSMikulas Patocka ol = &_dm_origins[origin_hash(origin)]; 415b735fedeSMikulas Patocka list_for_each_entry (o, ol, hash_list) 416b735fedeSMikulas Patocka if (bdev_equal(o->dev->bdev, origin)) 417b735fedeSMikulas Patocka return o; 418b735fedeSMikulas Patocka 419b735fedeSMikulas Patocka return NULL; 420b735fedeSMikulas Patocka } 421b735fedeSMikulas Patocka 422b735fedeSMikulas Patocka static void __insert_dm_origin(struct dm_origin *o) 423b735fedeSMikulas Patocka { 424b735fedeSMikulas Patocka struct list_head *sl = &_dm_origins[origin_hash(o->dev->bdev)]; 425b735fedeSMikulas Patocka list_add_tail(&o->hash_list, sl); 426b735fedeSMikulas Patocka } 427b735fedeSMikulas Patocka 428b735fedeSMikulas Patocka static void __remove_dm_origin(struct dm_origin *o) 429b735fedeSMikulas Patocka { 430b735fedeSMikulas Patocka list_del(&o->hash_list); 431b735fedeSMikulas Patocka } 432b735fedeSMikulas Patocka 4331da177e4SLinus Torvalds /* 434c1f0c183SMike Snitzer * _origins_lock must be held when calling this function. 435c1f0c183SMike Snitzer * Returns number of snapshots registered using the supplied cow device, plus: 436c1f0c183SMike Snitzer * snap_src - a snapshot suitable for use as a source of exception handover 437c1f0c183SMike Snitzer * snap_dest - a snapshot capable of receiving exception handover. 4389d3b15c4SMikulas Patocka * snap_merge - an existing snapshot-merge target linked to the same origin. 4399d3b15c4SMikulas Patocka * There can be at most one snapshot-merge target. The parameter is optional. 440c1f0c183SMike Snitzer * 4419d3b15c4SMikulas Patocka * Possible return values and states of snap_src and snap_dest. 442c1f0c183SMike Snitzer * 0: NULL, NULL - first new snapshot 443c1f0c183SMike Snitzer * 1: snap_src, NULL - normal snapshot 444c1f0c183SMike Snitzer * 2: snap_src, snap_dest - waiting for handover 445c1f0c183SMike Snitzer * 2: snap_src, NULL - handed over, waiting for old to be deleted 446c1f0c183SMike Snitzer * 1: NULL, snap_dest - source got destroyed without handover 447c1f0c183SMike Snitzer */ 448c1f0c183SMike Snitzer static int __find_snapshots_sharing_cow(struct dm_snapshot *snap, 449c1f0c183SMike Snitzer struct dm_snapshot **snap_src, 4509d3b15c4SMikulas Patocka struct dm_snapshot **snap_dest, 4519d3b15c4SMikulas Patocka struct dm_snapshot **snap_merge) 452c1f0c183SMike Snitzer { 453c1f0c183SMike Snitzer struct dm_snapshot *s; 454c1f0c183SMike Snitzer struct origin *o; 455c1f0c183SMike Snitzer int count = 0; 456c1f0c183SMike Snitzer int active; 457c1f0c183SMike Snitzer 458c1f0c183SMike Snitzer o = __lookup_origin(snap->origin->bdev); 459c1f0c183SMike Snitzer if (!o) 460c1f0c183SMike Snitzer goto out; 461c1f0c183SMike Snitzer 462c1f0c183SMike Snitzer list_for_each_entry(s, &o->snapshots, list) { 4639d3b15c4SMikulas Patocka if (dm_target_is_snapshot_merge(s->ti) && snap_merge) 4649d3b15c4SMikulas Patocka *snap_merge = s; 465c1f0c183SMike Snitzer if (!bdev_equal(s->cow->bdev, snap->cow->bdev)) 466c1f0c183SMike Snitzer continue; 467c1f0c183SMike Snitzer 4684ad8d880SNikos Tsironis down_read(&s->lock); 469c1f0c183SMike Snitzer active = s->active; 4704ad8d880SNikos Tsironis up_read(&s->lock); 471c1f0c183SMike Snitzer 472c1f0c183SMike Snitzer if (active) { 473c1f0c183SMike Snitzer if (snap_src) 474c1f0c183SMike Snitzer *snap_src = s; 475c1f0c183SMike Snitzer } else if (snap_dest) 476c1f0c183SMike Snitzer *snap_dest = s; 477c1f0c183SMike Snitzer 478c1f0c183SMike Snitzer count++; 479c1f0c183SMike Snitzer } 480c1f0c183SMike Snitzer 481c1f0c183SMike Snitzer out: 482c1f0c183SMike Snitzer return count; 483c1f0c183SMike Snitzer } 484c1f0c183SMike Snitzer 485c1f0c183SMike Snitzer /* 486c1f0c183SMike Snitzer * On success, returns 1 if this snapshot is a handover destination, 487c1f0c183SMike Snitzer * otherwise returns 0. 488c1f0c183SMike Snitzer */ 489c1f0c183SMike Snitzer static int __validate_exception_handover(struct dm_snapshot *snap) 490c1f0c183SMike Snitzer { 491c1f0c183SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 4929d3b15c4SMikulas Patocka struct dm_snapshot *snap_merge = NULL; 493c1f0c183SMike Snitzer 494c1f0c183SMike Snitzer /* Does snapshot need exceptions handed over to it? */ 4959d3b15c4SMikulas Patocka if ((__find_snapshots_sharing_cow(snap, &snap_src, &snap_dest, 4969d3b15c4SMikulas Patocka &snap_merge) == 2) || 497c1f0c183SMike Snitzer snap_dest) { 498c1f0c183SMike Snitzer snap->ti->error = "Snapshot cow pairing for exception " 499c1f0c183SMike Snitzer "table handover failed"; 500c1f0c183SMike Snitzer return -EINVAL; 501c1f0c183SMike Snitzer } 502c1f0c183SMike Snitzer 503c1f0c183SMike Snitzer /* 504c1f0c183SMike Snitzer * If no snap_src was found, snap cannot become a handover 505c1f0c183SMike Snitzer * destination. 506c1f0c183SMike Snitzer */ 507c1f0c183SMike Snitzer if (!snap_src) 508c1f0c183SMike Snitzer return 0; 509c1f0c183SMike Snitzer 5109d3b15c4SMikulas Patocka /* 5119d3b15c4SMikulas Patocka * Non-snapshot-merge handover? 5129d3b15c4SMikulas Patocka */ 5139d3b15c4SMikulas Patocka if (!dm_target_is_snapshot_merge(snap->ti)) 5149d3b15c4SMikulas Patocka return 1; 5159d3b15c4SMikulas Patocka 5169d3b15c4SMikulas Patocka /* 5179d3b15c4SMikulas Patocka * Do not allow more than one merging snapshot. 5189d3b15c4SMikulas Patocka */ 5199d3b15c4SMikulas Patocka if (snap_merge) { 5209d3b15c4SMikulas Patocka snap->ti->error = "A snapshot is already merging."; 5219d3b15c4SMikulas Patocka return -EINVAL; 5229d3b15c4SMikulas Patocka } 5239d3b15c4SMikulas Patocka 5241e03f97eSMikulas Patocka if (!snap_src->store->type->prepare_merge || 5251e03f97eSMikulas Patocka !snap_src->store->type->commit_merge) { 5261e03f97eSMikulas Patocka snap->ti->error = "Snapshot exception store does not " 5271e03f97eSMikulas Patocka "support snapshot-merge."; 5281e03f97eSMikulas Patocka return -EINVAL; 5291e03f97eSMikulas Patocka } 5301e03f97eSMikulas Patocka 531c1f0c183SMike Snitzer return 1; 532c1f0c183SMike Snitzer } 533c1f0c183SMike Snitzer 534c1f0c183SMike Snitzer static void __insert_snapshot(struct origin *o, struct dm_snapshot *s) 535c1f0c183SMike Snitzer { 536c1f0c183SMike Snitzer struct dm_snapshot *l; 537c1f0c183SMike Snitzer 538c1f0c183SMike Snitzer /* Sort the list according to chunk size, largest-first smallest-last */ 539c1f0c183SMike Snitzer list_for_each_entry(l, &o->snapshots, list) 540c1f0c183SMike Snitzer if (l->store->chunk_size < s->store->chunk_size) 541c1f0c183SMike Snitzer break; 542c1f0c183SMike Snitzer list_add_tail(&s->list, &l->list); 543c1f0c183SMike Snitzer } 544c1f0c183SMike Snitzer 545c1f0c183SMike Snitzer /* 5461da177e4SLinus Torvalds * Make a note of the snapshot and its origin so we can look it 5471da177e4SLinus Torvalds * up when the origin has a write on it. 548c1f0c183SMike Snitzer * 549c1f0c183SMike Snitzer * Also validate snapshot exception store handovers. 550c1f0c183SMike Snitzer * On success, returns 1 if this registration is a handover destination, 551c1f0c183SMike Snitzer * otherwise returns 0. 5521da177e4SLinus Torvalds */ 5531da177e4SLinus Torvalds static int register_snapshot(struct dm_snapshot *snap) 5541da177e4SLinus Torvalds { 555c1f0c183SMike Snitzer struct origin *o, *new_o = NULL; 5561da177e4SLinus Torvalds struct block_device *bdev = snap->origin->bdev; 557c1f0c183SMike Snitzer int r = 0; 5581da177e4SLinus Torvalds 55960c856c8SMikulas Patocka new_o = kmalloc(sizeof(*new_o), GFP_KERNEL); 56060c856c8SMikulas Patocka if (!new_o) 56160c856c8SMikulas Patocka return -ENOMEM; 56260c856c8SMikulas Patocka 5631da177e4SLinus Torvalds down_write(&_origins_lock); 5641da177e4SLinus Torvalds 565c1f0c183SMike Snitzer r = __validate_exception_handover(snap); 566c1f0c183SMike Snitzer if (r < 0) { 567c1f0c183SMike Snitzer kfree(new_o); 568c1f0c183SMike Snitzer goto out; 569c1f0c183SMike Snitzer } 570c1f0c183SMike Snitzer 571c1f0c183SMike Snitzer o = __lookup_origin(bdev); 57260c856c8SMikulas Patocka if (o) 57360c856c8SMikulas Patocka kfree(new_o); 57460c856c8SMikulas Patocka else { 5751da177e4SLinus Torvalds /* New origin */ 57660c856c8SMikulas Patocka o = new_o; 5771da177e4SLinus Torvalds 5781da177e4SLinus Torvalds /* Initialise the struct */ 5791da177e4SLinus Torvalds INIT_LIST_HEAD(&o->snapshots); 5801da177e4SLinus Torvalds o->bdev = bdev; 5811da177e4SLinus Torvalds 5821da177e4SLinus Torvalds __insert_origin(o); 5831da177e4SLinus Torvalds } 5841da177e4SLinus Torvalds 585c1f0c183SMike Snitzer __insert_snapshot(o, snap); 586c1f0c183SMike Snitzer 587c1f0c183SMike Snitzer out: 588c1f0c183SMike Snitzer up_write(&_origins_lock); 589c1f0c183SMike Snitzer 590c1f0c183SMike Snitzer return r; 591c1f0c183SMike Snitzer } 592c1f0c183SMike Snitzer 593c1f0c183SMike Snitzer /* 594c1f0c183SMike Snitzer * Move snapshot to correct place in list according to chunk size. 595c1f0c183SMike Snitzer */ 596c1f0c183SMike Snitzer static void reregister_snapshot(struct dm_snapshot *s) 597c1f0c183SMike Snitzer { 598c1f0c183SMike Snitzer struct block_device *bdev = s->origin->bdev; 599c1f0c183SMike Snitzer 600c1f0c183SMike Snitzer down_write(&_origins_lock); 601c1f0c183SMike Snitzer 602c1f0c183SMike Snitzer list_del(&s->list); 603c1f0c183SMike Snitzer __insert_snapshot(__lookup_origin(bdev), s); 6041da177e4SLinus Torvalds 6051da177e4SLinus Torvalds up_write(&_origins_lock); 6061da177e4SLinus Torvalds } 6071da177e4SLinus Torvalds 6081da177e4SLinus Torvalds static void unregister_snapshot(struct dm_snapshot *s) 6091da177e4SLinus Torvalds { 6101da177e4SLinus Torvalds struct origin *o; 6111da177e4SLinus Torvalds 6121da177e4SLinus Torvalds down_write(&_origins_lock); 6131da177e4SLinus Torvalds o = __lookup_origin(s->origin->bdev); 6141da177e4SLinus Torvalds 6151da177e4SLinus Torvalds list_del(&s->list); 616c1f0c183SMike Snitzer if (o && list_empty(&o->snapshots)) { 6171da177e4SLinus Torvalds list_del(&o->hash_list); 6181da177e4SLinus Torvalds kfree(o); 6191da177e4SLinus Torvalds } 6201da177e4SLinus Torvalds 6211da177e4SLinus Torvalds up_write(&_origins_lock); 6221da177e4SLinus Torvalds } 6231da177e4SLinus Torvalds 6241da177e4SLinus Torvalds /* 6251da177e4SLinus Torvalds * Implementation of the exception hash tables. 626d74f81f8SMilan Broz * The lowest hash_shift bits of the chunk number are ignored, allowing 627d74f81f8SMilan Broz * some consecutive chunks to be grouped together. 6281da177e4SLinus Torvalds */ 629f79ae415SNikos Tsironis static uint32_t exception_hash(struct dm_exception_table *et, chunk_t chunk); 630f79ae415SNikos Tsironis 631f79ae415SNikos Tsironis /* Lock to protect access to the completed and pending exception hash tables. */ 632f79ae415SNikos Tsironis struct dm_exception_table_lock { 633f79ae415SNikos Tsironis struct hlist_bl_head *complete_slot; 634f79ae415SNikos Tsironis struct hlist_bl_head *pending_slot; 635f79ae415SNikos Tsironis }; 636f79ae415SNikos Tsironis 637f79ae415SNikos Tsironis static void dm_exception_table_lock_init(struct dm_snapshot *s, chunk_t chunk, 638f79ae415SNikos Tsironis struct dm_exception_table_lock *lock) 639f79ae415SNikos Tsironis { 640f79ae415SNikos Tsironis struct dm_exception_table *complete = &s->complete; 641f79ae415SNikos Tsironis struct dm_exception_table *pending = &s->pending; 642f79ae415SNikos Tsironis 643f79ae415SNikos Tsironis lock->complete_slot = &complete->table[exception_hash(complete, chunk)]; 644f79ae415SNikos Tsironis lock->pending_slot = &pending->table[exception_hash(pending, chunk)]; 645f79ae415SNikos Tsironis } 646f79ae415SNikos Tsironis 647f79ae415SNikos Tsironis static void dm_exception_table_lock(struct dm_exception_table_lock *lock) 648f79ae415SNikos Tsironis { 649f79ae415SNikos Tsironis hlist_bl_lock(lock->complete_slot); 650f79ae415SNikos Tsironis hlist_bl_lock(lock->pending_slot); 651f79ae415SNikos Tsironis } 652f79ae415SNikos Tsironis 653f79ae415SNikos Tsironis static void dm_exception_table_unlock(struct dm_exception_table_lock *lock) 654f79ae415SNikos Tsironis { 655f79ae415SNikos Tsironis hlist_bl_unlock(lock->pending_slot); 656f79ae415SNikos Tsironis hlist_bl_unlock(lock->complete_slot); 657f79ae415SNikos Tsironis } 658f79ae415SNikos Tsironis 6593510cb94SJon Brassow static int dm_exception_table_init(struct dm_exception_table *et, 6603510cb94SJon Brassow uint32_t size, unsigned hash_shift) 6611da177e4SLinus Torvalds { 6621da177e4SLinus Torvalds unsigned int i; 6631da177e4SLinus Torvalds 664d74f81f8SMilan Broz et->hash_shift = hash_shift; 6651da177e4SLinus Torvalds et->hash_mask = size - 1; 6667a35693aSMatthew Wilcox (Oracle) et->table = kvmalloc_array(size, sizeof(struct hlist_bl_head), 6677a35693aSMatthew Wilcox (Oracle) GFP_KERNEL); 6681da177e4SLinus Torvalds if (!et->table) 6691da177e4SLinus Torvalds return -ENOMEM; 6701da177e4SLinus Torvalds 6711da177e4SLinus Torvalds for (i = 0; i < size; i++) 672f79ae415SNikos Tsironis INIT_HLIST_BL_HEAD(et->table + i); 6731da177e4SLinus Torvalds 6741da177e4SLinus Torvalds return 0; 6751da177e4SLinus Torvalds } 6761da177e4SLinus Torvalds 6773510cb94SJon Brassow static void dm_exception_table_exit(struct dm_exception_table *et, 678191437a5SJon Brassow struct kmem_cache *mem) 6791da177e4SLinus Torvalds { 680f79ae415SNikos Tsironis struct hlist_bl_head *slot; 681f79ae415SNikos Tsironis struct dm_exception *ex; 682f79ae415SNikos Tsironis struct hlist_bl_node *pos, *n; 6831da177e4SLinus Torvalds int i, size; 6841da177e4SLinus Torvalds 6851da177e4SLinus Torvalds size = et->hash_mask + 1; 6861da177e4SLinus Torvalds for (i = 0; i < size; i++) { 6871da177e4SLinus Torvalds slot = et->table + i; 6881da177e4SLinus Torvalds 689f79ae415SNikos Tsironis hlist_bl_for_each_entry_safe(ex, pos, n, slot, hash_list) 6901da177e4SLinus Torvalds kmem_cache_free(mem, ex); 6911da177e4SLinus Torvalds } 6921da177e4SLinus Torvalds 6937a35693aSMatthew Wilcox (Oracle) kvfree(et->table); 6941da177e4SLinus Torvalds } 6951da177e4SLinus Torvalds 696191437a5SJon Brassow static uint32_t exception_hash(struct dm_exception_table *et, chunk_t chunk) 6971da177e4SLinus Torvalds { 698d74f81f8SMilan Broz return (chunk >> et->hash_shift) & et->hash_mask; 6991da177e4SLinus Torvalds } 7001da177e4SLinus Torvalds 7013510cb94SJon Brassow static void dm_remove_exception(struct dm_exception *e) 7021da177e4SLinus Torvalds { 703f79ae415SNikos Tsironis hlist_bl_del(&e->hash_list); 7041da177e4SLinus Torvalds } 7051da177e4SLinus Torvalds 7061da177e4SLinus Torvalds /* 7071da177e4SLinus Torvalds * Return the exception data for a sector, or NULL if not 7081da177e4SLinus Torvalds * remapped. 7091da177e4SLinus Torvalds */ 7103510cb94SJon Brassow static struct dm_exception *dm_lookup_exception(struct dm_exception_table *et, 7111da177e4SLinus Torvalds chunk_t chunk) 7121da177e4SLinus Torvalds { 713f79ae415SNikos Tsironis struct hlist_bl_head *slot; 714f79ae415SNikos Tsironis struct hlist_bl_node *pos; 7151d4989c8SJon Brassow struct dm_exception *e; 7161da177e4SLinus Torvalds 7171da177e4SLinus Torvalds slot = &et->table[exception_hash(et, chunk)]; 718f79ae415SNikos Tsironis hlist_bl_for_each_entry(e, pos, slot, hash_list) 719d74f81f8SMilan Broz if (chunk >= e->old_chunk && 720d74f81f8SMilan Broz chunk <= e->old_chunk + dm_consecutive_chunk_count(e)) 7211da177e4SLinus Torvalds return e; 7221da177e4SLinus Torvalds 7231da177e4SLinus Torvalds return NULL; 7241da177e4SLinus Torvalds } 7251da177e4SLinus Torvalds 726119bc547SMikulas Patocka static struct dm_exception *alloc_completed_exception(gfp_t gfp) 7271da177e4SLinus Torvalds { 7281d4989c8SJon Brassow struct dm_exception *e; 7291da177e4SLinus Torvalds 730119bc547SMikulas Patocka e = kmem_cache_alloc(exception_cache, gfp); 731119bc547SMikulas Patocka if (!e && gfp == GFP_NOIO) 7321da177e4SLinus Torvalds e = kmem_cache_alloc(exception_cache, GFP_ATOMIC); 7331da177e4SLinus Torvalds 7341da177e4SLinus Torvalds return e; 7351da177e4SLinus Torvalds } 7361da177e4SLinus Torvalds 7373510cb94SJon Brassow static void free_completed_exception(struct dm_exception *e) 7381da177e4SLinus Torvalds { 7391da177e4SLinus Torvalds kmem_cache_free(exception_cache, e); 7401da177e4SLinus Torvalds } 7411da177e4SLinus Torvalds 74292e86812SMikulas Patocka static struct dm_snap_pending_exception *alloc_pending_exception(struct dm_snapshot *s) 7431da177e4SLinus Torvalds { 7446f1c819cSKent Overstreet struct dm_snap_pending_exception *pe = mempool_alloc(&s->pending_pool, 74592e86812SMikulas Patocka GFP_NOIO); 74692e86812SMikulas Patocka 747879129d2SMikulas Patocka atomic_inc(&s->pending_exceptions_count); 74892e86812SMikulas Patocka pe->snap = s; 74992e86812SMikulas Patocka 75092e86812SMikulas Patocka return pe; 7511da177e4SLinus Torvalds } 7521da177e4SLinus Torvalds 753028867acSAlasdair G Kergon static void free_pending_exception(struct dm_snap_pending_exception *pe) 7541da177e4SLinus Torvalds { 755879129d2SMikulas Patocka struct dm_snapshot *s = pe->snap; 756879129d2SMikulas Patocka 7576f1c819cSKent Overstreet mempool_free(pe, &s->pending_pool); 7584e857c58SPeter Zijlstra smp_mb__before_atomic(); 759879129d2SMikulas Patocka atomic_dec(&s->pending_exceptions_count); 7601da177e4SLinus Torvalds } 7611da177e4SLinus Torvalds 7623510cb94SJon Brassow static void dm_insert_exception(struct dm_exception_table *eh, 7631d4989c8SJon Brassow struct dm_exception *new_e) 764d74f81f8SMilan Broz { 765f79ae415SNikos Tsironis struct hlist_bl_head *l; 766f79ae415SNikos Tsironis struct hlist_bl_node *pos; 7671d4989c8SJon Brassow struct dm_exception *e = NULL; 768d74f81f8SMilan Broz 769d74f81f8SMilan Broz l = &eh->table[exception_hash(eh, new_e->old_chunk)]; 770d74f81f8SMilan Broz 771d74f81f8SMilan Broz /* Add immediately if this table doesn't support consecutive chunks */ 772d74f81f8SMilan Broz if (!eh->hash_shift) 773d74f81f8SMilan Broz goto out; 774d74f81f8SMilan Broz 775d74f81f8SMilan Broz /* List is ordered by old_chunk */ 776f79ae415SNikos Tsironis hlist_bl_for_each_entry(e, pos, l, hash_list) { 777d74f81f8SMilan Broz /* Insert after an existing chunk? */ 778d74f81f8SMilan Broz if (new_e->old_chunk == (e->old_chunk + 779d74f81f8SMilan Broz dm_consecutive_chunk_count(e) + 1) && 780d74f81f8SMilan Broz new_e->new_chunk == (dm_chunk_number(e->new_chunk) + 781d74f81f8SMilan Broz dm_consecutive_chunk_count(e) + 1)) { 782d74f81f8SMilan Broz dm_consecutive_chunk_count_inc(e); 7833510cb94SJon Brassow free_completed_exception(new_e); 784d74f81f8SMilan Broz return; 785d74f81f8SMilan Broz } 786d74f81f8SMilan Broz 787d74f81f8SMilan Broz /* Insert before an existing chunk? */ 788d74f81f8SMilan Broz if (new_e->old_chunk == (e->old_chunk - 1) && 789d74f81f8SMilan Broz new_e->new_chunk == (dm_chunk_number(e->new_chunk) - 1)) { 790d74f81f8SMilan Broz dm_consecutive_chunk_count_inc(e); 791d74f81f8SMilan Broz e->old_chunk--; 792d74f81f8SMilan Broz e->new_chunk--; 7933510cb94SJon Brassow free_completed_exception(new_e); 794d74f81f8SMilan Broz return; 795d74f81f8SMilan Broz } 796d74f81f8SMilan Broz 797f79ae415SNikos Tsironis if (new_e->old_chunk < e->old_chunk) 798d74f81f8SMilan Broz break; 799d74f81f8SMilan Broz } 800d74f81f8SMilan Broz 801d74f81f8SMilan Broz out: 802f79ae415SNikos Tsironis if (!e) { 803f79ae415SNikos Tsironis /* 804f79ae415SNikos Tsironis * Either the table doesn't support consecutive chunks or slot 805f79ae415SNikos Tsironis * l is empty. 806f79ae415SNikos Tsironis */ 807f79ae415SNikos Tsironis hlist_bl_add_head(&new_e->hash_list, l); 808f79ae415SNikos Tsironis } else if (new_e->old_chunk < e->old_chunk) { 809f79ae415SNikos Tsironis /* Add before an existing exception */ 810f79ae415SNikos Tsironis hlist_bl_add_before(&new_e->hash_list, &e->hash_list); 811f79ae415SNikos Tsironis } else { 812f79ae415SNikos Tsironis /* Add to l's tail: e is the last exception in this slot */ 813f79ae415SNikos Tsironis hlist_bl_add_behind(&new_e->hash_list, &e->hash_list); 814f79ae415SNikos Tsironis } 815d74f81f8SMilan Broz } 816d74f81f8SMilan Broz 817a159c1acSJonathan Brassow /* 818a159c1acSJonathan Brassow * Callback used by the exception stores to load exceptions when 819a159c1acSJonathan Brassow * initialising. 820a159c1acSJonathan Brassow */ 821a159c1acSJonathan Brassow static int dm_add_exception(void *context, chunk_t old, chunk_t new) 8221da177e4SLinus Torvalds { 823f79ae415SNikos Tsironis struct dm_exception_table_lock lock; 824a159c1acSJonathan Brassow struct dm_snapshot *s = context; 8251d4989c8SJon Brassow struct dm_exception *e; 8261da177e4SLinus Torvalds 827119bc547SMikulas Patocka e = alloc_completed_exception(GFP_KERNEL); 8281da177e4SLinus Torvalds if (!e) 8291da177e4SLinus Torvalds return -ENOMEM; 8301da177e4SLinus Torvalds 8311da177e4SLinus Torvalds e->old_chunk = old; 832d74f81f8SMilan Broz 833d74f81f8SMilan Broz /* Consecutive_count is implicitly initialised to zero */ 8341da177e4SLinus Torvalds e->new_chunk = new; 835d74f81f8SMilan Broz 836f79ae415SNikos Tsironis /* 837f79ae415SNikos Tsironis * Although there is no need to lock access to the exception tables 838f79ae415SNikos Tsironis * here, if we don't then hlist_bl_add_head(), called by 839f79ae415SNikos Tsironis * dm_insert_exception(), will complain about accessing the 840f79ae415SNikos Tsironis * corresponding list without locking it first. 841f79ae415SNikos Tsironis */ 842f79ae415SNikos Tsironis dm_exception_table_lock_init(s, old, &lock); 843f79ae415SNikos Tsironis 844f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 8453510cb94SJon Brassow dm_insert_exception(&s->complete, e); 846f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 847d74f81f8SMilan Broz 8481da177e4SLinus Torvalds return 0; 8491da177e4SLinus Torvalds } 8501da177e4SLinus Torvalds 8517e201b35SMikulas Patocka /* 8527e201b35SMikulas Patocka * Return a minimum chunk size of all snapshots that have the specified origin. 8537e201b35SMikulas Patocka * Return zero if the origin has no snapshots. 8547e201b35SMikulas Patocka */ 855542f9038SMike Snitzer static uint32_t __minimum_chunk_size(struct origin *o) 8567e201b35SMikulas Patocka { 8577e201b35SMikulas Patocka struct dm_snapshot *snap; 8587ee06ddcSMikulas Patocka unsigned chunk_size = rounddown_pow_of_two(UINT_MAX); 8597e201b35SMikulas Patocka 8607e201b35SMikulas Patocka if (o) 8617e201b35SMikulas Patocka list_for_each_entry(snap, &o->snapshots, list) 8627ee06ddcSMikulas Patocka chunk_size = min(chunk_size, snap->store->chunk_size); 8637e201b35SMikulas Patocka 864542f9038SMike Snitzer return (uint32_t) chunk_size; 8657e201b35SMikulas Patocka } 8667e201b35SMikulas Patocka 8671da177e4SLinus Torvalds /* 8681da177e4SLinus Torvalds * Hard coded magic. 8691da177e4SLinus Torvalds */ 8701da177e4SLinus Torvalds static int calc_max_buckets(void) 8711da177e4SLinus Torvalds { 8721da177e4SLinus Torvalds /* use a fixed size of 2MB */ 8731da177e4SLinus Torvalds unsigned long mem = 2 * 1024 * 1024; 874f79ae415SNikos Tsironis mem /= sizeof(struct hlist_bl_head); 8751da177e4SLinus Torvalds 8761da177e4SLinus Torvalds return mem; 8771da177e4SLinus Torvalds } 8781da177e4SLinus Torvalds 8791da177e4SLinus Torvalds /* 8801da177e4SLinus Torvalds * Allocate room for a suitable hash table. 8811da177e4SLinus Torvalds */ 882fee1998eSJonathan Brassow static int init_hash_tables(struct dm_snapshot *s) 8831da177e4SLinus Torvalds { 88460e356f3SMikulas Patocka sector_t hash_size, cow_dev_size, max_buckets; 8851da177e4SLinus Torvalds 8861da177e4SLinus Torvalds /* 8871da177e4SLinus Torvalds * Calculate based on the size of the original volume or 8881da177e4SLinus Torvalds * the COW volume... 8891da177e4SLinus Torvalds */ 890fc56f6fbSMike Snitzer cow_dev_size = get_dev_size(s->cow->bdev); 8911da177e4SLinus Torvalds max_buckets = calc_max_buckets(); 8921da177e4SLinus Torvalds 89360e356f3SMikulas Patocka hash_size = cow_dev_size >> s->store->chunk_shift; 8941da177e4SLinus Torvalds hash_size = min(hash_size, max_buckets); 8951da177e4SLinus Torvalds 8968e87b9b8SMikulas Patocka if (hash_size < 64) 8978e87b9b8SMikulas Patocka hash_size = 64; 8988defd830SRobert P. J. Day hash_size = rounddown_pow_of_two(hash_size); 8993510cb94SJon Brassow if (dm_exception_table_init(&s->complete, hash_size, 900d74f81f8SMilan Broz DM_CHUNK_CONSECUTIVE_BITS)) 9011da177e4SLinus Torvalds return -ENOMEM; 9021da177e4SLinus Torvalds 9031da177e4SLinus Torvalds /* 9041da177e4SLinus Torvalds * Allocate hash table for in-flight exceptions 9051da177e4SLinus Torvalds * Make this smaller than the real hash table 9061da177e4SLinus Torvalds */ 9071da177e4SLinus Torvalds hash_size >>= 3; 9081da177e4SLinus Torvalds if (hash_size < 64) 9091da177e4SLinus Torvalds hash_size = 64; 9101da177e4SLinus Torvalds 9113510cb94SJon Brassow if (dm_exception_table_init(&s->pending, hash_size, 0)) { 9123510cb94SJon Brassow dm_exception_table_exit(&s->complete, exception_cache); 9131da177e4SLinus Torvalds return -ENOMEM; 9141da177e4SLinus Torvalds } 9151da177e4SLinus Torvalds 9161da177e4SLinus Torvalds return 0; 9171da177e4SLinus Torvalds } 9181da177e4SLinus Torvalds 9191e03f97eSMikulas Patocka static void merge_shutdown(struct dm_snapshot *s) 9201e03f97eSMikulas Patocka { 9211e03f97eSMikulas Patocka clear_bit_unlock(RUNNING_MERGE, &s->state_bits); 9224e857c58SPeter Zijlstra smp_mb__after_atomic(); 9231e03f97eSMikulas Patocka wake_up_bit(&s->state_bits, RUNNING_MERGE); 9241e03f97eSMikulas Patocka } 9251e03f97eSMikulas Patocka 9269fe86254SMikulas Patocka static struct bio *__release_queued_bios_after_merge(struct dm_snapshot *s) 9279fe86254SMikulas Patocka { 9289fe86254SMikulas Patocka s->first_merging_chunk = 0; 9299fe86254SMikulas Patocka s->num_merging_chunks = 0; 9309fe86254SMikulas Patocka 9319fe86254SMikulas Patocka return bio_list_get(&s->bios_queued_during_merge); 9329fe86254SMikulas Patocka } 9339fe86254SMikulas Patocka 9341e03f97eSMikulas Patocka /* 9351e03f97eSMikulas Patocka * Remove one chunk from the index of completed exceptions. 9361e03f97eSMikulas Patocka */ 9371e03f97eSMikulas Patocka static int __remove_single_exception_chunk(struct dm_snapshot *s, 9381e03f97eSMikulas Patocka chunk_t old_chunk) 9391e03f97eSMikulas Patocka { 9401e03f97eSMikulas Patocka struct dm_exception *e; 9411e03f97eSMikulas Patocka 9421e03f97eSMikulas Patocka e = dm_lookup_exception(&s->complete, old_chunk); 9431e03f97eSMikulas Patocka if (!e) { 9441e03f97eSMikulas Patocka DMERR("Corruption detected: exception for block %llu is " 9451e03f97eSMikulas Patocka "on disk but not in memory", 9461e03f97eSMikulas Patocka (unsigned long long)old_chunk); 9471e03f97eSMikulas Patocka return -EINVAL; 9481e03f97eSMikulas Patocka } 9491e03f97eSMikulas Patocka 9501e03f97eSMikulas Patocka /* 9511e03f97eSMikulas Patocka * If this is the only chunk using this exception, remove exception. 9521e03f97eSMikulas Patocka */ 9531e03f97eSMikulas Patocka if (!dm_consecutive_chunk_count(e)) { 9541e03f97eSMikulas Patocka dm_remove_exception(e); 9551e03f97eSMikulas Patocka free_completed_exception(e); 9561e03f97eSMikulas Patocka return 0; 9571e03f97eSMikulas Patocka } 9581e03f97eSMikulas Patocka 9591e03f97eSMikulas Patocka /* 9601e03f97eSMikulas Patocka * The chunk may be either at the beginning or the end of a 9611e03f97eSMikulas Patocka * group of consecutive chunks - never in the middle. We are 9621e03f97eSMikulas Patocka * removing chunks in the opposite order to that in which they 9631e03f97eSMikulas Patocka * were added, so this should always be true. 9641e03f97eSMikulas Patocka * Decrement the consecutive chunk counter and adjust the 9651e03f97eSMikulas Patocka * starting point if necessary. 9661e03f97eSMikulas Patocka */ 9671e03f97eSMikulas Patocka if (old_chunk == e->old_chunk) { 9681e03f97eSMikulas Patocka e->old_chunk++; 9691e03f97eSMikulas Patocka e->new_chunk++; 9701e03f97eSMikulas Patocka } else if (old_chunk != e->old_chunk + 9711e03f97eSMikulas Patocka dm_consecutive_chunk_count(e)) { 9721e03f97eSMikulas Patocka DMERR("Attempt to merge block %llu from the " 9731e03f97eSMikulas Patocka "middle of a chunk range [%llu - %llu]", 9741e03f97eSMikulas Patocka (unsigned long long)old_chunk, 9751e03f97eSMikulas Patocka (unsigned long long)e->old_chunk, 9761e03f97eSMikulas Patocka (unsigned long long) 9771e03f97eSMikulas Patocka e->old_chunk + dm_consecutive_chunk_count(e)); 9781e03f97eSMikulas Patocka return -EINVAL; 9791e03f97eSMikulas Patocka } 9801e03f97eSMikulas Patocka 9811e03f97eSMikulas Patocka dm_consecutive_chunk_count_dec(e); 9821e03f97eSMikulas Patocka 9831e03f97eSMikulas Patocka return 0; 9841e03f97eSMikulas Patocka } 9851e03f97eSMikulas Patocka 9869fe86254SMikulas Patocka static void flush_bios(struct bio *bio); 9879fe86254SMikulas Patocka 9889fe86254SMikulas Patocka static int remove_single_exception_chunk(struct dm_snapshot *s) 9891e03f97eSMikulas Patocka { 9909fe86254SMikulas Patocka struct bio *b = NULL; 9919fe86254SMikulas Patocka int r; 9929fe86254SMikulas Patocka chunk_t old_chunk = s->first_merging_chunk + s->num_merging_chunks - 1; 9931e03f97eSMikulas Patocka 9944ad8d880SNikos Tsironis down_write(&s->lock); 9959fe86254SMikulas Patocka 9969fe86254SMikulas Patocka /* 9979fe86254SMikulas Patocka * Process chunks (and associated exceptions) in reverse order 9989fe86254SMikulas Patocka * so that dm_consecutive_chunk_count_dec() accounting works. 9999fe86254SMikulas Patocka */ 10009fe86254SMikulas Patocka do { 10011e03f97eSMikulas Patocka r = __remove_single_exception_chunk(s, old_chunk); 10029fe86254SMikulas Patocka if (r) 10039fe86254SMikulas Patocka goto out; 10049fe86254SMikulas Patocka } while (old_chunk-- > s->first_merging_chunk); 10059fe86254SMikulas Patocka 10069fe86254SMikulas Patocka b = __release_queued_bios_after_merge(s); 10079fe86254SMikulas Patocka 10089fe86254SMikulas Patocka out: 10094ad8d880SNikos Tsironis up_write(&s->lock); 10109fe86254SMikulas Patocka if (b) 10119fe86254SMikulas Patocka flush_bios(b); 10121e03f97eSMikulas Patocka 10131e03f97eSMikulas Patocka return r; 10141e03f97eSMikulas Patocka } 10151e03f97eSMikulas Patocka 101673dfd078SMikulas Patocka static int origin_write_extent(struct dm_snapshot *merging_snap, 101773dfd078SMikulas Patocka sector_t sector, unsigned chunk_size); 101873dfd078SMikulas Patocka 10191e03f97eSMikulas Patocka static void merge_callback(int read_err, unsigned long write_err, 10201e03f97eSMikulas Patocka void *context); 10211e03f97eSMikulas Patocka 102273dfd078SMikulas Patocka static uint64_t read_pending_exceptions_done_count(void) 102373dfd078SMikulas Patocka { 102473dfd078SMikulas Patocka uint64_t pending_exceptions_done; 102573dfd078SMikulas Patocka 102673dfd078SMikulas Patocka spin_lock(&_pending_exceptions_done_spinlock); 102773dfd078SMikulas Patocka pending_exceptions_done = _pending_exceptions_done_count; 102873dfd078SMikulas Patocka spin_unlock(&_pending_exceptions_done_spinlock); 102973dfd078SMikulas Patocka 103073dfd078SMikulas Patocka return pending_exceptions_done; 103173dfd078SMikulas Patocka } 103273dfd078SMikulas Patocka 103373dfd078SMikulas Patocka static void increment_pending_exceptions_done_count(void) 103473dfd078SMikulas Patocka { 103573dfd078SMikulas Patocka spin_lock(&_pending_exceptions_done_spinlock); 103673dfd078SMikulas Patocka _pending_exceptions_done_count++; 103773dfd078SMikulas Patocka spin_unlock(&_pending_exceptions_done_spinlock); 103873dfd078SMikulas Patocka 103973dfd078SMikulas Patocka wake_up_all(&_pending_exceptions_done); 104073dfd078SMikulas Patocka } 104173dfd078SMikulas Patocka 10421e03f97eSMikulas Patocka static void snapshot_merge_next_chunks(struct dm_snapshot *s) 10431e03f97eSMikulas Patocka { 10448a2d5286SMike Snitzer int i, linear_chunks; 10451e03f97eSMikulas Patocka chunk_t old_chunk, new_chunk; 10461e03f97eSMikulas Patocka struct dm_io_region src, dest; 10478a2d5286SMike Snitzer sector_t io_size; 104873dfd078SMikulas Patocka uint64_t previous_count; 10491e03f97eSMikulas Patocka 10501e03f97eSMikulas Patocka BUG_ON(!test_bit(RUNNING_MERGE, &s->state_bits)); 10511e03f97eSMikulas Patocka if (unlikely(test_bit(SHUTDOWN_MERGE, &s->state_bits))) 10521e03f97eSMikulas Patocka goto shut; 10531e03f97eSMikulas Patocka 10541e03f97eSMikulas Patocka /* 10551e03f97eSMikulas Patocka * valid flag never changes during merge, so no lock required. 10561e03f97eSMikulas Patocka */ 10571e03f97eSMikulas Patocka if (!s->valid) { 10581e03f97eSMikulas Patocka DMERR("Snapshot is invalid: can't merge"); 10591e03f97eSMikulas Patocka goto shut; 10601e03f97eSMikulas Patocka } 10611e03f97eSMikulas Patocka 10628a2d5286SMike Snitzer linear_chunks = s->store->type->prepare_merge(s->store, &old_chunk, 10638a2d5286SMike Snitzer &new_chunk); 10648a2d5286SMike Snitzer if (linear_chunks <= 0) { 1065d8ddb1cfSMike Snitzer if (linear_chunks < 0) { 10661e03f97eSMikulas Patocka DMERR("Read error in exception store: " 10671e03f97eSMikulas Patocka "shutting down merge"); 10684ad8d880SNikos Tsironis down_write(&s->lock); 10691d1dda8cSzhengbin s->merge_failed = true; 10704ad8d880SNikos Tsironis up_write(&s->lock); 1071d8ddb1cfSMike Snitzer } 10721e03f97eSMikulas Patocka goto shut; 10731e03f97eSMikulas Patocka } 10741e03f97eSMikulas Patocka 10758a2d5286SMike Snitzer /* Adjust old_chunk and new_chunk to reflect start of linear region */ 10768a2d5286SMike Snitzer old_chunk = old_chunk + 1 - linear_chunks; 10778a2d5286SMike Snitzer new_chunk = new_chunk + 1 - linear_chunks; 10788a2d5286SMike Snitzer 10798a2d5286SMike Snitzer /* 10808a2d5286SMike Snitzer * Use one (potentially large) I/O to copy all 'linear_chunks' 10818a2d5286SMike Snitzer * from the exception store to the origin 10828a2d5286SMike Snitzer */ 10838a2d5286SMike Snitzer io_size = linear_chunks * s->store->chunk_size; 10841e03f97eSMikulas Patocka 10851e03f97eSMikulas Patocka dest.bdev = s->origin->bdev; 10861e03f97eSMikulas Patocka dest.sector = chunk_to_sector(s->store, old_chunk); 10878a2d5286SMike Snitzer dest.count = min(io_size, get_dev_size(dest.bdev) - dest.sector); 10881e03f97eSMikulas Patocka 10891e03f97eSMikulas Patocka src.bdev = s->cow->bdev; 10901e03f97eSMikulas Patocka src.sector = chunk_to_sector(s->store, new_chunk); 10911e03f97eSMikulas Patocka src.count = dest.count; 10921e03f97eSMikulas Patocka 109373dfd078SMikulas Patocka /* 109473dfd078SMikulas Patocka * Reallocate any exceptions needed in other snapshots then 109573dfd078SMikulas Patocka * wait for the pending exceptions to complete. 109673dfd078SMikulas Patocka * Each time any pending exception (globally on the system) 109773dfd078SMikulas Patocka * completes we are woken and repeat the process to find out 109873dfd078SMikulas Patocka * if we can proceed. While this may not seem a particularly 109973dfd078SMikulas Patocka * efficient algorithm, it is not expected to have any 110073dfd078SMikulas Patocka * significant impact on performance. 110173dfd078SMikulas Patocka */ 110273dfd078SMikulas Patocka previous_count = read_pending_exceptions_done_count(); 11038a2d5286SMike Snitzer while (origin_write_extent(s, dest.sector, io_size)) { 110473dfd078SMikulas Patocka wait_event(_pending_exceptions_done, 110573dfd078SMikulas Patocka (read_pending_exceptions_done_count() != 110673dfd078SMikulas Patocka previous_count)); 110773dfd078SMikulas Patocka /* Retry after the wait, until all exceptions are done. */ 110873dfd078SMikulas Patocka previous_count = read_pending_exceptions_done_count(); 110973dfd078SMikulas Patocka } 111073dfd078SMikulas Patocka 11114ad8d880SNikos Tsironis down_write(&s->lock); 11129fe86254SMikulas Patocka s->first_merging_chunk = old_chunk; 11138a2d5286SMike Snitzer s->num_merging_chunks = linear_chunks; 11144ad8d880SNikos Tsironis up_write(&s->lock); 11159fe86254SMikulas Patocka 11168a2d5286SMike Snitzer /* Wait until writes to all 'linear_chunks' drain */ 11178a2d5286SMike Snitzer for (i = 0; i < linear_chunks; i++) 11188a2d5286SMike Snitzer __check_for_conflicting_io(s, old_chunk + i); 11199fe86254SMikulas Patocka 11201e03f97eSMikulas Patocka dm_kcopyd_copy(s->kcopyd_client, &src, 1, &dest, 0, merge_callback, s); 11211e03f97eSMikulas Patocka return; 11221e03f97eSMikulas Patocka 11231e03f97eSMikulas Patocka shut: 11241e03f97eSMikulas Patocka merge_shutdown(s); 11251e03f97eSMikulas Patocka } 11261e03f97eSMikulas Patocka 11279fe86254SMikulas Patocka static void error_bios(struct bio *bio); 11289fe86254SMikulas Patocka 1129fcc42338SAkilesh Kailash static int flush_data(struct dm_snapshot *s) 1130fcc42338SAkilesh Kailash { 1131fcc42338SAkilesh Kailash struct bio *flush_bio = &s->flush_bio; 1132fcc42338SAkilesh Kailash 1133fcc42338SAkilesh Kailash bio_reset(flush_bio); 1134fcc42338SAkilesh Kailash bio_set_dev(flush_bio, s->origin->bdev); 1135fcc42338SAkilesh Kailash flush_bio->bi_opf = REQ_OP_WRITE | REQ_PREFLUSH; 1136fcc42338SAkilesh Kailash 1137fcc42338SAkilesh Kailash return submit_bio_wait(flush_bio); 1138fcc42338SAkilesh Kailash } 1139fcc42338SAkilesh Kailash 11401e03f97eSMikulas Patocka static void merge_callback(int read_err, unsigned long write_err, void *context) 11411e03f97eSMikulas Patocka { 11421e03f97eSMikulas Patocka struct dm_snapshot *s = context; 11439fe86254SMikulas Patocka struct bio *b = NULL; 11441e03f97eSMikulas Patocka 11451e03f97eSMikulas Patocka if (read_err || write_err) { 11461e03f97eSMikulas Patocka if (read_err) 11471e03f97eSMikulas Patocka DMERR("Read error: shutting down merge."); 11481e03f97eSMikulas Patocka else 11491e03f97eSMikulas Patocka DMERR("Write error: shutting down merge."); 11501e03f97eSMikulas Patocka goto shut; 11511e03f97eSMikulas Patocka } 11521e03f97eSMikulas Patocka 1153fcc42338SAkilesh Kailash if (flush_data(s) < 0) { 1154fcc42338SAkilesh Kailash DMERR("Flush after merge failed: shutting down merge"); 1155fcc42338SAkilesh Kailash goto shut; 1156fcc42338SAkilesh Kailash } 1157fcc42338SAkilesh Kailash 11589fe86254SMikulas Patocka if (s->store->type->commit_merge(s->store, 11599fe86254SMikulas Patocka s->num_merging_chunks) < 0) { 11601e03f97eSMikulas Patocka DMERR("Write error in exception store: shutting down merge"); 11611e03f97eSMikulas Patocka goto shut; 11621e03f97eSMikulas Patocka } 11631e03f97eSMikulas Patocka 11649fe86254SMikulas Patocka if (remove_single_exception_chunk(s) < 0) 11659fe86254SMikulas Patocka goto shut; 11669fe86254SMikulas Patocka 11671e03f97eSMikulas Patocka snapshot_merge_next_chunks(s); 11681e03f97eSMikulas Patocka 11691e03f97eSMikulas Patocka return; 11701e03f97eSMikulas Patocka 11711e03f97eSMikulas Patocka shut: 11724ad8d880SNikos Tsironis down_write(&s->lock); 11731d1dda8cSzhengbin s->merge_failed = true; 11749fe86254SMikulas Patocka b = __release_queued_bios_after_merge(s); 11754ad8d880SNikos Tsironis up_write(&s->lock); 11769fe86254SMikulas Patocka error_bios(b); 11779fe86254SMikulas Patocka 11781e03f97eSMikulas Patocka merge_shutdown(s); 11791e03f97eSMikulas Patocka } 11801e03f97eSMikulas Patocka 11811e03f97eSMikulas Patocka static void start_merge(struct dm_snapshot *s) 11821e03f97eSMikulas Patocka { 11831e03f97eSMikulas Patocka if (!test_and_set_bit(RUNNING_MERGE, &s->state_bits)) 11841e03f97eSMikulas Patocka snapshot_merge_next_chunks(s); 11851e03f97eSMikulas Patocka } 11861e03f97eSMikulas Patocka 11871e03f97eSMikulas Patocka /* 11881e03f97eSMikulas Patocka * Stop the merging process and wait until it finishes. 11891e03f97eSMikulas Patocka */ 11901e03f97eSMikulas Patocka static void stop_merge(struct dm_snapshot *s) 11911e03f97eSMikulas Patocka { 11921e03f97eSMikulas Patocka set_bit(SHUTDOWN_MERGE, &s->state_bits); 119374316201SNeilBrown wait_on_bit(&s->state_bits, RUNNING_MERGE, TASK_UNINTERRUPTIBLE); 11941e03f97eSMikulas Patocka clear_bit(SHUTDOWN_MERGE, &s->state_bits); 11951e03f97eSMikulas Patocka } 11961e03f97eSMikulas Patocka 11972e602385SMike Snitzer static int parse_snapshot_features(struct dm_arg_set *as, struct dm_snapshot *s, 11982e602385SMike Snitzer struct dm_target *ti) 11992e602385SMike Snitzer { 12002e602385SMike Snitzer int r; 12012e602385SMike Snitzer unsigned argc; 12022e602385SMike Snitzer const char *arg_name; 12032e602385SMike Snitzer 12042e602385SMike Snitzer static const struct dm_arg _args[] = { 12052e602385SMike Snitzer {0, 2, "Invalid number of feature arguments"}, 12062e602385SMike Snitzer }; 12072e602385SMike Snitzer 12081da177e4SLinus Torvalds /* 12092e602385SMike Snitzer * No feature arguments supplied. 12102e602385SMike Snitzer */ 12112e602385SMike Snitzer if (!as->argc) 12122e602385SMike Snitzer return 0; 12132e602385SMike Snitzer 12142e602385SMike Snitzer r = dm_read_arg_group(_args, as, &argc, &ti->error); 12152e602385SMike Snitzer if (r) 12162e602385SMike Snitzer return -EINVAL; 12172e602385SMike Snitzer 12182e602385SMike Snitzer while (argc && !r) { 12192e602385SMike Snitzer arg_name = dm_shift_arg(as); 12202e602385SMike Snitzer argc--; 12212e602385SMike Snitzer 12222e602385SMike Snitzer if (!strcasecmp(arg_name, "discard_zeroes_cow")) 12232e602385SMike Snitzer s->discard_zeroes_cow = true; 12242e602385SMike Snitzer 12252e602385SMike Snitzer else if (!strcasecmp(arg_name, "discard_passdown_origin")) 12262e602385SMike Snitzer s->discard_passdown_origin = true; 12272e602385SMike Snitzer 12282e602385SMike Snitzer else { 12292e602385SMike Snitzer ti->error = "Unrecognised feature requested"; 12302e602385SMike Snitzer r = -EINVAL; 12312e602385SMike Snitzer break; 12322e602385SMike Snitzer } 12332e602385SMike Snitzer } 12342e602385SMike Snitzer 12352e602385SMike Snitzer if (!s->discard_zeroes_cow && s->discard_passdown_origin) { 12362e602385SMike Snitzer /* 12372e602385SMike Snitzer * TODO: really these are disjoint.. but ti->num_discard_bios 12382e602385SMike Snitzer * and dm_bio_get_target_bio_nr() require rigid constraints. 12392e602385SMike Snitzer */ 12402e602385SMike Snitzer ti->error = "discard_passdown_origin feature depends on discard_zeroes_cow"; 12412e602385SMike Snitzer r = -EINVAL; 12422e602385SMike Snitzer } 12432e602385SMike Snitzer 12442e602385SMike Snitzer return r; 12452e602385SMike Snitzer } 12462e602385SMike Snitzer 12472e602385SMike Snitzer /* 12482e602385SMike Snitzer * Construct a snapshot mapping: 12492e602385SMike Snitzer * <origin_dev> <COW-dev> <p|po|n> <chunk-size> [<# feature args> [<arg>]*] 12501da177e4SLinus Torvalds */ 12511da177e4SLinus Torvalds static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv) 12521da177e4SLinus Torvalds { 12531da177e4SLinus Torvalds struct dm_snapshot *s; 12542e602385SMike Snitzer struct dm_arg_set as; 1255cd45daffSMikulas Patocka int i; 12561da177e4SLinus Torvalds int r = -EINVAL; 1257fc56f6fbSMike Snitzer char *origin_path, *cow_path; 12584df2bf46SDingXiang dev_t origin_dev, cow_dev; 125955a62eefSAlasdair G Kergon unsigned args_used, num_flush_bios = 1; 126010b8106aSMike Snitzer fmode_t origin_mode = FMODE_READ; 12611da177e4SLinus Torvalds 12622e602385SMike Snitzer if (argc < 4) { 12632e602385SMike Snitzer ti->error = "requires 4 or more arguments"; 12641da177e4SLinus Torvalds r = -EINVAL; 1265fc56f6fbSMike Snitzer goto bad; 12661da177e4SLinus Torvalds } 12671da177e4SLinus Torvalds 126810b8106aSMike Snitzer if (dm_target_is_snapshot_merge(ti)) { 126955a62eefSAlasdair G Kergon num_flush_bios = 2; 127010b8106aSMike Snitzer origin_mode = FMODE_WRITE; 127110b8106aSMike Snitzer } 127210b8106aSMike Snitzer 1273d3775354SKent Overstreet s = kzalloc(sizeof(*s), GFP_KERNEL); 1274fee1998eSJonathan Brassow if (!s) { 1275a2d2b034SJonathan Brassow ti->error = "Cannot allocate private snapshot structure"; 12761da177e4SLinus Torvalds r = -ENOMEM; 1277fc56f6fbSMike Snitzer goto bad; 12781da177e4SLinus Torvalds } 12791da177e4SLinus Torvalds 12802e602385SMike Snitzer as.argc = argc; 12812e602385SMike Snitzer as.argv = argv; 12822e602385SMike Snitzer dm_consume_args(&as, 4); 12832e602385SMike Snitzer r = parse_snapshot_features(&as, s, ti); 12842e602385SMike Snitzer if (r) 12852e602385SMike Snitzer goto bad_features; 12862e602385SMike Snitzer 1287c2411045SMikulas Patocka origin_path = argv[0]; 1288c2411045SMikulas Patocka argv++; 1289c2411045SMikulas Patocka argc--; 1290c2411045SMikulas Patocka 1291c2411045SMikulas Patocka r = dm_get_device(ti, origin_path, origin_mode, &s->origin); 1292c2411045SMikulas Patocka if (r) { 1293c2411045SMikulas Patocka ti->error = "Cannot get origin device"; 1294c2411045SMikulas Patocka goto bad_origin; 1295c2411045SMikulas Patocka } 12964df2bf46SDingXiang origin_dev = s->origin->bdev->bd_dev; 1297c2411045SMikulas Patocka 1298fc56f6fbSMike Snitzer cow_path = argv[0]; 1299fc56f6fbSMike Snitzer argv++; 1300fc56f6fbSMike Snitzer argc--; 1301fc56f6fbSMike Snitzer 13024df2bf46SDingXiang cow_dev = dm_get_dev_t(cow_path); 13034df2bf46SDingXiang if (cow_dev && cow_dev == origin_dev) { 13044df2bf46SDingXiang ti->error = "COW device cannot be the same as origin device"; 13054df2bf46SDingXiang r = -EINVAL; 13064df2bf46SDingXiang goto bad_cow; 13074df2bf46SDingXiang } 13084df2bf46SDingXiang 1309024d37e9SMilan Broz r = dm_get_device(ti, cow_path, dm_table_get_mode(ti->table), &s->cow); 1310fc56f6fbSMike Snitzer if (r) { 1311fc56f6fbSMike Snitzer ti->error = "Cannot get COW device"; 1312fc56f6fbSMike Snitzer goto bad_cow; 1313fc56f6fbSMike Snitzer } 1314fc56f6fbSMike Snitzer 1315fc56f6fbSMike Snitzer r = dm_exception_store_create(ti, argc, argv, s, &args_used, &s->store); 1316fc56f6fbSMike Snitzer if (r) { 1317fc56f6fbSMike Snitzer ti->error = "Couldn't create exception store"; 1318fc56f6fbSMike Snitzer r = -EINVAL; 1319fc56f6fbSMike Snitzer goto bad_store; 1320fc56f6fbSMike Snitzer } 1321fc56f6fbSMike Snitzer 1322fc56f6fbSMike Snitzer argv += args_used; 1323fc56f6fbSMike Snitzer argc -= args_used; 1324fc56f6fbSMike Snitzer 1325fc56f6fbSMike Snitzer s->ti = ti; 13261da177e4SLinus Torvalds s->valid = 1; 132776c44f6dSMikulas Patocka s->snapshot_overflowed = 0; 1328aa14edebSAlasdair G Kergon s->active = 0; 1329879129d2SMikulas Patocka atomic_set(&s->pending_exceptions_count, 0); 13303f1637f2SNikos Tsironis spin_lock_init(&s->pe_allocation_lock); 1331230c83afSMikulas Patocka s->exception_start_sequence = 0; 1332230c83afSMikulas Patocka s->exception_complete_sequence = 0; 13333db2776dSDavid Jeffery s->out_of_order_tree = RB_ROOT; 13344ad8d880SNikos Tsironis init_rwsem(&s->lock); 1335c1f0c183SMike Snitzer INIT_LIST_HEAD(&s->list); 1336ca3a931fSAlasdair G Kergon spin_lock_init(&s->pe_lock); 13371e03f97eSMikulas Patocka s->state_bits = 0; 13381d1dda8cSzhengbin s->merge_failed = false; 13399fe86254SMikulas Patocka s->first_merging_chunk = 0; 13409fe86254SMikulas Patocka s->num_merging_chunks = 0; 13419fe86254SMikulas Patocka bio_list_init(&s->bios_queued_during_merge); 1342fcc42338SAkilesh Kailash bio_init(&s->flush_bio, NULL, 0); 13431da177e4SLinus Torvalds 13441da177e4SLinus Torvalds /* Allocate hash table for COW data */ 1345fee1998eSJonathan Brassow if (init_hash_tables(s)) { 13461da177e4SLinus Torvalds ti->error = "Unable to allocate hash table space"; 13471da177e4SLinus Torvalds r = -ENOMEM; 1348fee1998eSJonathan Brassow goto bad_hash_tables; 13491da177e4SLinus Torvalds } 13501da177e4SLinus Torvalds 1351b2155578SMikulas Patocka init_waitqueue_head(&s->in_progress_wait); 1352721b1d98SNikos Tsironis 1353df5d2e90SMikulas Patocka s->kcopyd_client = dm_kcopyd_client_create(&dm_kcopyd_throttle); 1354fa34ce73SMikulas Patocka if (IS_ERR(s->kcopyd_client)) { 1355fa34ce73SMikulas Patocka r = PTR_ERR(s->kcopyd_client); 13561da177e4SLinus Torvalds ti->error = "Could not create kcopyd client"; 1357fee1998eSJonathan Brassow goto bad_kcopyd; 13581da177e4SLinus Torvalds } 13591da177e4SLinus Torvalds 13606f1c819cSKent Overstreet r = mempool_init_slab_pool(&s->pending_pool, MIN_IOS, pending_cache); 13616f1c819cSKent Overstreet if (r) { 136292e86812SMikulas Patocka ti->error = "Could not allocate mempool for pending exceptions"; 1363fee1998eSJonathan Brassow goto bad_pending_pool; 136492e86812SMikulas Patocka } 136592e86812SMikulas Patocka 1366cd45daffSMikulas Patocka for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) 1367cd45daffSMikulas Patocka INIT_HLIST_HEAD(&s->tracked_chunk_hash[i]); 1368cd45daffSMikulas Patocka 1369cd45daffSMikulas Patocka spin_lock_init(&s->tracked_chunk_lock); 1370cd45daffSMikulas Patocka 1371c1f0c183SMike Snitzer ti->private = s; 137255a62eefSAlasdair G Kergon ti->num_flush_bios = num_flush_bios; 13732e602385SMike Snitzer if (s->discard_zeroes_cow) 13742e602385SMike Snitzer ti->num_discard_bios = (s->discard_passdown_origin ? 2 : 1); 137530187e1dSMike Snitzer ti->per_io_data_size = sizeof(struct dm_snap_tracked_chunk); 1376c1f0c183SMike Snitzer 1377c1f0c183SMike Snitzer /* Add snapshot to the list of snapshots for this origin */ 1378c1f0c183SMike Snitzer /* Exceptions aren't triggered till snapshot_resume() is called */ 1379c1f0c183SMike Snitzer r = register_snapshot(s); 1380c1f0c183SMike Snitzer if (r == -ENOMEM) { 1381c1f0c183SMike Snitzer ti->error = "Snapshot origin struct allocation failed"; 1382c1f0c183SMike Snitzer goto bad_load_and_register; 1383c1f0c183SMike Snitzer } else if (r < 0) { 1384c1f0c183SMike Snitzer /* invalid handover, register_snapshot has set ti->error */ 1385c1f0c183SMike Snitzer goto bad_load_and_register; 1386c1f0c183SMike Snitzer } 1387c1f0c183SMike Snitzer 1388c1f0c183SMike Snitzer /* 1389c1f0c183SMike Snitzer * Metadata must only be loaded into one table at once, so skip this 1390c1f0c183SMike Snitzer * if metadata will be handed over during resume. 1391c1f0c183SMike Snitzer * Chunk size will be set during the handover - set it to zero to 1392c1f0c183SMike Snitzer * ensure it's ignored. 1393c1f0c183SMike Snitzer */ 1394c1f0c183SMike Snitzer if (r > 0) { 1395c1f0c183SMike Snitzer s->store->chunk_size = 0; 1396c1f0c183SMike Snitzer return 0; 1397c1f0c183SMike Snitzer } 1398c1f0c183SMike Snitzer 1399493df71cSJonathan Brassow r = s->store->type->read_metadata(s->store, dm_add_exception, 1400493df71cSJonathan Brassow (void *)s); 14010764147bSMilan Broz if (r < 0) { 1402f9cea4f7SMark McLoughlin ti->error = "Failed to read snapshot metadata"; 1403c1f0c183SMike Snitzer goto bad_read_metadata; 14040764147bSMilan Broz } else if (r > 0) { 14050764147bSMilan Broz s->valid = 0; 14060764147bSMilan Broz DMWARN("Snapshot is marked invalid."); 1407f9cea4f7SMark McLoughlin } 1408aa14edebSAlasdair G Kergon 14093f2412dcSMikulas Patocka if (!s->store->chunk_size) { 14103f2412dcSMikulas Patocka ti->error = "Chunk size not set"; 1411*c699a0dbSMikulas Patocka r = -EINVAL; 1412c1f0c183SMike Snitzer goto bad_read_metadata; 14133f2412dcSMikulas Patocka } 1414542f9038SMike Snitzer 1415542f9038SMike Snitzer r = dm_set_target_max_io_len(ti, s->store->chunk_size); 1416542f9038SMike Snitzer if (r) 1417542f9038SMike Snitzer goto bad_read_metadata; 14181da177e4SLinus Torvalds 14191da177e4SLinus Torvalds return 0; 14201da177e4SLinus Torvalds 1421c1f0c183SMike Snitzer bad_read_metadata: 1422c1f0c183SMike Snitzer unregister_snapshot(s); 1423cd45daffSMikulas Patocka bad_load_and_register: 14246f1c819cSKent Overstreet mempool_exit(&s->pending_pool); 1425fee1998eSJonathan Brassow bad_pending_pool: 1426eb69aca5SHeinz Mauelshagen dm_kcopyd_client_destroy(s->kcopyd_client); 1427fee1998eSJonathan Brassow bad_kcopyd: 14283510cb94SJon Brassow dm_exception_table_exit(&s->pending, pending_cache); 14293510cb94SJon Brassow dm_exception_table_exit(&s->complete, exception_cache); 1430fee1998eSJonathan Brassow bad_hash_tables: 1431fc56f6fbSMike Snitzer dm_exception_store_destroy(s->store); 1432fc56f6fbSMike Snitzer bad_store: 1433fc56f6fbSMike Snitzer dm_put_device(ti, s->cow); 1434fc56f6fbSMike Snitzer bad_cow: 1435c2411045SMikulas Patocka dm_put_device(ti, s->origin); 1436c2411045SMikulas Patocka bad_origin: 14372e602385SMike Snitzer bad_features: 14381da177e4SLinus Torvalds kfree(s); 1439fc56f6fbSMike Snitzer bad: 14401da177e4SLinus Torvalds return r; 14411da177e4SLinus Torvalds } 14421da177e4SLinus Torvalds 144331c93a0cSMilan Broz static void __free_exceptions(struct dm_snapshot *s) 144431c93a0cSMilan Broz { 1445eb69aca5SHeinz Mauelshagen dm_kcopyd_client_destroy(s->kcopyd_client); 144631c93a0cSMilan Broz s->kcopyd_client = NULL; 144731c93a0cSMilan Broz 14483510cb94SJon Brassow dm_exception_table_exit(&s->pending, pending_cache); 14493510cb94SJon Brassow dm_exception_table_exit(&s->complete, exception_cache); 145031c93a0cSMilan Broz } 145131c93a0cSMilan Broz 1452c1f0c183SMike Snitzer static void __handover_exceptions(struct dm_snapshot *snap_src, 1453c1f0c183SMike Snitzer struct dm_snapshot *snap_dest) 1454c1f0c183SMike Snitzer { 1455c1f0c183SMike Snitzer union { 1456c1f0c183SMike Snitzer struct dm_exception_table table_swap; 1457c1f0c183SMike Snitzer struct dm_exception_store *store_swap; 1458c1f0c183SMike Snitzer } u; 1459c1f0c183SMike Snitzer 1460c1f0c183SMike Snitzer /* 1461c1f0c183SMike Snitzer * Swap all snapshot context information between the two instances. 1462c1f0c183SMike Snitzer */ 1463c1f0c183SMike Snitzer u.table_swap = snap_dest->complete; 1464c1f0c183SMike Snitzer snap_dest->complete = snap_src->complete; 1465c1f0c183SMike Snitzer snap_src->complete = u.table_swap; 1466c1f0c183SMike Snitzer 1467c1f0c183SMike Snitzer u.store_swap = snap_dest->store; 1468c1f0c183SMike Snitzer snap_dest->store = snap_src->store; 1469b0d3cc01SMike Snitzer snap_dest->store->userspace_supports_overflow = u.store_swap->userspace_supports_overflow; 1470c1f0c183SMike Snitzer snap_src->store = u.store_swap; 1471c1f0c183SMike Snitzer 1472c1f0c183SMike Snitzer snap_dest->store->snap = snap_dest; 1473c1f0c183SMike Snitzer snap_src->store->snap = snap_src; 1474c1f0c183SMike Snitzer 1475542f9038SMike Snitzer snap_dest->ti->max_io_len = snap_dest->store->chunk_size; 1476c1f0c183SMike Snitzer snap_dest->valid = snap_src->valid; 147776c44f6dSMikulas Patocka snap_dest->snapshot_overflowed = snap_src->snapshot_overflowed; 1478c1f0c183SMike Snitzer 1479c1f0c183SMike Snitzer /* 1480c1f0c183SMike Snitzer * Set source invalid to ensure it receives no further I/O. 1481c1f0c183SMike Snitzer */ 1482c1f0c183SMike Snitzer snap_src->valid = 0; 1483c1f0c183SMike Snitzer } 1484c1f0c183SMike Snitzer 14851da177e4SLinus Torvalds static void snapshot_dtr(struct dm_target *ti) 14861da177e4SLinus Torvalds { 1487cd45daffSMikulas Patocka #ifdef CONFIG_DM_DEBUG 1488cd45daffSMikulas Patocka int i; 1489cd45daffSMikulas Patocka #endif 1490028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 1491c1f0c183SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 14921da177e4SLinus Torvalds 1493c1f0c183SMike Snitzer down_read(&_origins_lock); 1494c1f0c183SMike Snitzer /* Check whether exception handover must be cancelled */ 14959d3b15c4SMikulas Patocka (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); 1496c1f0c183SMike Snitzer if (snap_src && snap_dest && (s == snap_src)) { 14974ad8d880SNikos Tsironis down_write(&snap_dest->lock); 1498c1f0c183SMike Snitzer snap_dest->valid = 0; 14994ad8d880SNikos Tsironis up_write(&snap_dest->lock); 1500c1f0c183SMike Snitzer DMERR("Cancelling snapshot handover."); 1501c1f0c183SMike Snitzer } 1502c1f0c183SMike Snitzer up_read(&_origins_lock); 1503c1f0c183SMike Snitzer 15041e03f97eSMikulas Patocka if (dm_target_is_snapshot_merge(ti)) 15051e03f97eSMikulas Patocka stop_merge(s); 15061e03f97eSMikulas Patocka 1507138728dcSAlasdair G Kergon /* Prevent further origin writes from using this snapshot. */ 1508138728dcSAlasdair G Kergon /* After this returns there can be no new kcopyd jobs. */ 15091da177e4SLinus Torvalds unregister_snapshot(s); 15101da177e4SLinus Torvalds 1511879129d2SMikulas Patocka while (atomic_read(&s->pending_exceptions_count)) 151290fa1527SMikulas Patocka msleep(1); 1513879129d2SMikulas Patocka /* 15146f1c819cSKent Overstreet * Ensure instructions in mempool_exit aren't reordered 1515879129d2SMikulas Patocka * before atomic_read. 1516879129d2SMikulas Patocka */ 1517879129d2SMikulas Patocka smp_mb(); 1518879129d2SMikulas Patocka 1519cd45daffSMikulas Patocka #ifdef CONFIG_DM_DEBUG 1520cd45daffSMikulas Patocka for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) 1521cd45daffSMikulas Patocka BUG_ON(!hlist_empty(&s->tracked_chunk_hash[i])); 1522cd45daffSMikulas Patocka #endif 1523cd45daffSMikulas Patocka 152431c93a0cSMilan Broz __free_exceptions(s); 15251da177e4SLinus Torvalds 15266f1c819cSKent Overstreet mempool_exit(&s->pending_pool); 152792e86812SMikulas Patocka 1528fee1998eSJonathan Brassow dm_exception_store_destroy(s->store); 1529138728dcSAlasdair G Kergon 1530fcc42338SAkilesh Kailash bio_uninit(&s->flush_bio); 1531fcc42338SAkilesh Kailash 1532fc56f6fbSMike Snitzer dm_put_device(ti, s->cow); 1533fc56f6fbSMike Snitzer 1534c2411045SMikulas Patocka dm_put_device(ti, s->origin); 1535c2411045SMikulas Patocka 1536b2155578SMikulas Patocka WARN_ON(s->in_progress); 1537b2155578SMikulas Patocka 15381da177e4SLinus Torvalds kfree(s); 15391da177e4SLinus Torvalds } 15401da177e4SLinus Torvalds 1541a2f83e8bSMikulas Patocka static void account_start_copy(struct dm_snapshot *s) 1542a2f83e8bSMikulas Patocka { 1543b2155578SMikulas Patocka spin_lock(&s->in_progress_wait.lock); 1544b2155578SMikulas Patocka s->in_progress++; 1545b2155578SMikulas Patocka spin_unlock(&s->in_progress_wait.lock); 1546a2f83e8bSMikulas Patocka } 1547a2f83e8bSMikulas Patocka 1548a2f83e8bSMikulas Patocka static void account_end_copy(struct dm_snapshot *s) 1549a2f83e8bSMikulas Patocka { 1550b2155578SMikulas Patocka spin_lock(&s->in_progress_wait.lock); 1551b2155578SMikulas Patocka BUG_ON(!s->in_progress); 1552b2155578SMikulas Patocka s->in_progress--; 1553b2155578SMikulas Patocka if (likely(s->in_progress <= cow_threshold) && 1554b2155578SMikulas Patocka unlikely(waitqueue_active(&s->in_progress_wait))) 1555b2155578SMikulas Patocka wake_up_locked(&s->in_progress_wait); 1556b2155578SMikulas Patocka spin_unlock(&s->in_progress_wait.lock); 1557b2155578SMikulas Patocka } 1558b2155578SMikulas Patocka 1559b2155578SMikulas Patocka static bool wait_for_in_progress(struct dm_snapshot *s, bool unlock_origins) 1560b2155578SMikulas Patocka { 1561b2155578SMikulas Patocka if (unlikely(s->in_progress > cow_threshold)) { 1562b2155578SMikulas Patocka spin_lock(&s->in_progress_wait.lock); 1563b2155578SMikulas Patocka if (likely(s->in_progress > cow_threshold)) { 1564b2155578SMikulas Patocka /* 1565b2155578SMikulas Patocka * NOTE: this throttle doesn't account for whether 1566b2155578SMikulas Patocka * the caller is servicing an IO that will trigger a COW 1567b2155578SMikulas Patocka * so excess throttling may result for chunks not required 1568b2155578SMikulas Patocka * to be COW'd. But if cow_threshold was reached, extra 1569b2155578SMikulas Patocka * throttling is unlikely to negatively impact performance. 1570b2155578SMikulas Patocka */ 1571b2155578SMikulas Patocka DECLARE_WAITQUEUE(wait, current); 1572b2155578SMikulas Patocka __add_wait_queue(&s->in_progress_wait, &wait); 1573b2155578SMikulas Patocka __set_current_state(TASK_UNINTERRUPTIBLE); 1574b2155578SMikulas Patocka spin_unlock(&s->in_progress_wait.lock); 1575b2155578SMikulas Patocka if (unlock_origins) 1576b2155578SMikulas Patocka up_read(&_origins_lock); 1577b2155578SMikulas Patocka io_schedule(); 1578b2155578SMikulas Patocka remove_wait_queue(&s->in_progress_wait, &wait); 1579b2155578SMikulas Patocka return false; 1580b2155578SMikulas Patocka } 1581b2155578SMikulas Patocka spin_unlock(&s->in_progress_wait.lock); 1582b2155578SMikulas Patocka } 1583b2155578SMikulas Patocka return true; 1584a2f83e8bSMikulas Patocka } 1585a2f83e8bSMikulas Patocka 15861da177e4SLinus Torvalds /* 15871da177e4SLinus Torvalds * Flush a list of buffers. 15881da177e4SLinus Torvalds */ 15891da177e4SLinus Torvalds static void flush_bios(struct bio *bio) 15901da177e4SLinus Torvalds { 15911da177e4SLinus Torvalds struct bio *n; 15921da177e4SLinus Torvalds 15931da177e4SLinus Torvalds while (bio) { 15941da177e4SLinus Torvalds n = bio->bi_next; 15951da177e4SLinus Torvalds bio->bi_next = NULL; 1596ed00aabdSChristoph Hellwig submit_bio_noacct(bio); 15971da177e4SLinus Torvalds bio = n; 15981da177e4SLinus Torvalds } 15991da177e4SLinus Torvalds } 16001da177e4SLinus Torvalds 1601b2155578SMikulas Patocka static int do_origin(struct dm_dev *origin, struct bio *bio, bool limit); 1602515ad66cSMikulas Patocka 1603515ad66cSMikulas Patocka /* 1604515ad66cSMikulas Patocka * Flush a list of buffers. 1605515ad66cSMikulas Patocka */ 1606515ad66cSMikulas Patocka static void retry_origin_bios(struct dm_snapshot *s, struct bio *bio) 1607515ad66cSMikulas Patocka { 1608515ad66cSMikulas Patocka struct bio *n; 1609515ad66cSMikulas Patocka int r; 1610515ad66cSMikulas Patocka 1611515ad66cSMikulas Patocka while (bio) { 1612515ad66cSMikulas Patocka n = bio->bi_next; 1613515ad66cSMikulas Patocka bio->bi_next = NULL; 1614b2155578SMikulas Patocka r = do_origin(s->origin, bio, false); 1615515ad66cSMikulas Patocka if (r == DM_MAPIO_REMAPPED) 1616ed00aabdSChristoph Hellwig submit_bio_noacct(bio); 1617515ad66cSMikulas Patocka bio = n; 1618515ad66cSMikulas Patocka } 1619515ad66cSMikulas Patocka } 1620515ad66cSMikulas Patocka 16211da177e4SLinus Torvalds /* 16221da177e4SLinus Torvalds * Error a list of buffers. 16231da177e4SLinus Torvalds */ 16241da177e4SLinus Torvalds static void error_bios(struct bio *bio) 16251da177e4SLinus Torvalds { 16261da177e4SLinus Torvalds struct bio *n; 16271da177e4SLinus Torvalds 16281da177e4SLinus Torvalds while (bio) { 16291da177e4SLinus Torvalds n = bio->bi_next; 16301da177e4SLinus Torvalds bio->bi_next = NULL; 16316712ecf8SNeilBrown bio_io_error(bio); 16321da177e4SLinus Torvalds bio = n; 16331da177e4SLinus Torvalds } 16341da177e4SLinus Torvalds } 16351da177e4SLinus Torvalds 1636695368acSAlasdair G Kergon static void __invalidate_snapshot(struct dm_snapshot *s, int err) 163776df1c65SAlasdair G Kergon { 163876df1c65SAlasdair G Kergon if (!s->valid) 163976df1c65SAlasdair G Kergon return; 164076df1c65SAlasdair G Kergon 164176df1c65SAlasdair G Kergon if (err == -EIO) 164276df1c65SAlasdair G Kergon DMERR("Invalidating snapshot: Error reading/writing."); 164376df1c65SAlasdair G Kergon else if (err == -ENOMEM) 164476df1c65SAlasdair G Kergon DMERR("Invalidating snapshot: Unable to allocate exception."); 164576df1c65SAlasdair G Kergon 1646493df71cSJonathan Brassow if (s->store->type->drop_snapshot) 1647493df71cSJonathan Brassow s->store->type->drop_snapshot(s->store); 164876df1c65SAlasdair G Kergon 164976df1c65SAlasdair G Kergon s->valid = 0; 165076df1c65SAlasdair G Kergon 1651fc56f6fbSMike Snitzer dm_table_event(s->ti->table); 165276df1c65SAlasdair G Kergon } 165376df1c65SAlasdair G Kergon 16543f1637f2SNikos Tsironis static void invalidate_snapshot(struct dm_snapshot *s, int err) 16553f1637f2SNikos Tsironis { 16563f1637f2SNikos Tsironis down_write(&s->lock); 16573f1637f2SNikos Tsironis __invalidate_snapshot(s, err); 16583f1637f2SNikos Tsironis up_write(&s->lock); 16593f1637f2SNikos Tsironis } 16603f1637f2SNikos Tsironis 1661385277bfSMikulas Patocka static void pending_complete(void *context, int success) 16621da177e4SLinus Torvalds { 1663385277bfSMikulas Patocka struct dm_snap_pending_exception *pe = context; 16641d4989c8SJon Brassow struct dm_exception *e; 16651da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 16669d493fa8SAlasdair G Kergon struct bio *origin_bios = NULL; 16679d493fa8SAlasdair G Kergon struct bio *snapshot_bios = NULL; 1668a6e50b40SMikulas Patocka struct bio *full_bio = NULL; 1669f79ae415SNikos Tsironis struct dm_exception_table_lock lock; 16709d493fa8SAlasdair G Kergon int error = 0; 16711da177e4SLinus Torvalds 1672f79ae415SNikos Tsironis dm_exception_table_lock_init(s, pe->e.old_chunk, &lock); 1673f79ae415SNikos Tsironis 167476df1c65SAlasdair G Kergon if (!success) { 167576df1c65SAlasdair G Kergon /* Read/write error - snapshot is unusable */ 16763f1637f2SNikos Tsironis invalidate_snapshot(s, -EIO); 16779d493fa8SAlasdair G Kergon error = 1; 1678f79ae415SNikos Tsironis 1679f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 168076df1c65SAlasdair G Kergon goto out; 168176df1c65SAlasdair G Kergon } 168276df1c65SAlasdair G Kergon 1683119bc547SMikulas Patocka e = alloc_completed_exception(GFP_NOIO); 168476df1c65SAlasdair G Kergon if (!e) { 16853f1637f2SNikos Tsironis invalidate_snapshot(s, -ENOMEM); 16869d493fa8SAlasdair G Kergon error = 1; 1687f79ae415SNikos Tsironis 1688f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 16891da177e4SLinus Torvalds goto out; 16901da177e4SLinus Torvalds } 16911da177e4SLinus Torvalds *e = pe->e; 16921da177e4SLinus Torvalds 16933f1637f2SNikos Tsironis down_read(&s->lock); 1694f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 16959d493fa8SAlasdair G Kergon if (!s->valid) { 16963f1637f2SNikos Tsironis up_read(&s->lock); 16973510cb94SJon Brassow free_completed_exception(e); 16989d493fa8SAlasdair G Kergon error = 1; 16993f1637f2SNikos Tsironis 17009d493fa8SAlasdair G Kergon goto out; 17019d493fa8SAlasdair G Kergon } 17029d493fa8SAlasdair G Kergon 1703a8d41b59SMikulas Patocka /* 170465fc7c37SNikos Tsironis * Add a proper exception. After inserting the completed exception all 170565fc7c37SNikos Tsironis * subsequent snapshot reads to this chunk will be redirected to the 170665fc7c37SNikos Tsironis * COW device. This ensures that we do not starve. Moreover, as long 170765fc7c37SNikos Tsironis * as the pending exception exists, neither origin writes nor snapshot 170865fc7c37SNikos Tsironis * merging can overwrite the chunk in origin. 17091da177e4SLinus Torvalds */ 17103510cb94SJon Brassow dm_insert_exception(&s->complete, e); 17113f1637f2SNikos Tsironis up_read(&s->lock); 17121da177e4SLinus Torvalds 171365fc7c37SNikos Tsironis /* Wait for conflicting reads to drain */ 171465fc7c37SNikos Tsironis if (__chunk_is_tracked(s, pe->e.old_chunk)) { 1715f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 171665fc7c37SNikos Tsironis __check_for_conflicting_io(s, pe->e.old_chunk); 1717f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 171865fc7c37SNikos Tsironis } 171965fc7c37SNikos Tsironis 17201da177e4SLinus Torvalds out: 172165fc7c37SNikos Tsironis /* Remove the in-flight exception from the list */ 17223510cb94SJon Brassow dm_remove_exception(&pe->e); 1723f79ae415SNikos Tsironis 1724f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 1725f79ae415SNikos Tsironis 17269d493fa8SAlasdair G Kergon snapshot_bios = bio_list_get(&pe->snapshot_bios); 1727515ad66cSMikulas Patocka origin_bios = bio_list_get(&pe->origin_bios); 1728a6e50b40SMikulas Patocka full_bio = pe->full_bio; 1729fe3265b1SMikulas Patocka if (full_bio) 1730a6e50b40SMikulas Patocka full_bio->bi_end_io = pe->full_bio_end_io; 173173dfd078SMikulas Patocka increment_pending_exceptions_done_count(); 173273dfd078SMikulas Patocka 17339d493fa8SAlasdair G Kergon /* Submit any pending write bios */ 1734a6e50b40SMikulas Patocka if (error) { 1735a6e50b40SMikulas Patocka if (full_bio) 1736a6e50b40SMikulas Patocka bio_io_error(full_bio); 17379d493fa8SAlasdair G Kergon error_bios(snapshot_bios); 1738a6e50b40SMikulas Patocka } else { 1739a6e50b40SMikulas Patocka if (full_bio) 17404246a0b6SChristoph Hellwig bio_endio(full_bio); 17419d493fa8SAlasdair G Kergon flush_bios(snapshot_bios); 1742a6e50b40SMikulas Patocka } 17439d493fa8SAlasdair G Kergon 1744515ad66cSMikulas Patocka retry_origin_bios(s, origin_bios); 174522aa66a3SMikulas Patocka 174622aa66a3SMikulas Patocka free_pending_exception(pe); 17471da177e4SLinus Torvalds } 17481da177e4SLinus Torvalds 1749230c83afSMikulas Patocka static void complete_exception(struct dm_snap_pending_exception *pe) 1750230c83afSMikulas Patocka { 1751230c83afSMikulas Patocka struct dm_snapshot *s = pe->snap; 1752230c83afSMikulas Patocka 1753230c83afSMikulas Patocka /* Update the metadata if we are persistent */ 1754385277bfSMikulas Patocka s->store->type->commit_exception(s->store, &pe->e, !pe->copy_error, 1755385277bfSMikulas Patocka pending_complete, pe); 1756230c83afSMikulas Patocka } 1757230c83afSMikulas Patocka 17581da177e4SLinus Torvalds /* 17591da177e4SLinus Torvalds * Called when the copy I/O has finished. kcopyd actually runs 17601da177e4SLinus Torvalds * this code so don't block. 17611da177e4SLinus Torvalds */ 17624cdc1d1fSAlasdair G Kergon static void copy_callback(int read_err, unsigned long write_err, void *context) 17631da177e4SLinus Torvalds { 1764028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = context; 17651da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 17661da177e4SLinus Torvalds 1767230c83afSMikulas Patocka pe->copy_error = read_err || write_err; 17681da177e4SLinus Torvalds 1769230c83afSMikulas Patocka if (pe->exception_sequence == s->exception_complete_sequence) { 17703db2776dSDavid Jeffery struct rb_node *next; 17713db2776dSDavid Jeffery 1772230c83afSMikulas Patocka s->exception_complete_sequence++; 1773230c83afSMikulas Patocka complete_exception(pe); 1774230c83afSMikulas Patocka 17753db2776dSDavid Jeffery next = rb_first(&s->out_of_order_tree); 17763db2776dSDavid Jeffery while (next) { 17773db2776dSDavid Jeffery pe = rb_entry(next, struct dm_snap_pending_exception, 17783db2776dSDavid Jeffery out_of_order_node); 1779230c83afSMikulas Patocka if (pe->exception_sequence != s->exception_complete_sequence) 1780230c83afSMikulas Patocka break; 17813db2776dSDavid Jeffery next = rb_next(next); 1782230c83afSMikulas Patocka s->exception_complete_sequence++; 17833db2776dSDavid Jeffery rb_erase(&pe->out_of_order_node, &s->out_of_order_tree); 1784230c83afSMikulas Patocka complete_exception(pe); 17853db2776dSDavid Jeffery cond_resched(); 1786230c83afSMikulas Patocka } 1787230c83afSMikulas Patocka } else { 17883db2776dSDavid Jeffery struct rb_node *parent = NULL; 17893db2776dSDavid Jeffery struct rb_node **p = &s->out_of_order_tree.rb_node; 1790230c83afSMikulas Patocka struct dm_snap_pending_exception *pe2; 1791230c83afSMikulas Patocka 17923db2776dSDavid Jeffery while (*p) { 17933db2776dSDavid Jeffery pe2 = rb_entry(*p, struct dm_snap_pending_exception, out_of_order_node); 17943db2776dSDavid Jeffery parent = *p; 17953db2776dSDavid Jeffery 17963db2776dSDavid Jeffery BUG_ON(pe->exception_sequence == pe2->exception_sequence); 17973db2776dSDavid Jeffery if (pe->exception_sequence < pe2->exception_sequence) 17983db2776dSDavid Jeffery p = &((*p)->rb_left); 17993db2776dSDavid Jeffery else 18003db2776dSDavid Jeffery p = &((*p)->rb_right); 1801230c83afSMikulas Patocka } 18023db2776dSDavid Jeffery 18033db2776dSDavid Jeffery rb_link_node(&pe->out_of_order_node, parent, p); 18043db2776dSDavid Jeffery rb_insert_color(&pe->out_of_order_node, &s->out_of_order_tree); 1805230c83afSMikulas Patocka } 1806a2f83e8bSMikulas Patocka account_end_copy(s); 18071da177e4SLinus Torvalds } 18081da177e4SLinus Torvalds 18091da177e4SLinus Torvalds /* 18101da177e4SLinus Torvalds * Dispatches the copy operation to kcopyd. 18111da177e4SLinus Torvalds */ 1812028867acSAlasdair G Kergon static void start_copy(struct dm_snap_pending_exception *pe) 18131da177e4SLinus Torvalds { 18141da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 181522a1ceb1SHeinz Mauelshagen struct dm_io_region src, dest; 18161da177e4SLinus Torvalds struct block_device *bdev = s->origin->bdev; 18171da177e4SLinus Torvalds sector_t dev_size; 18181da177e4SLinus Torvalds 18191da177e4SLinus Torvalds dev_size = get_dev_size(bdev); 18201da177e4SLinus Torvalds 18211da177e4SLinus Torvalds src.bdev = bdev; 182271fab00aSJonathan Brassow src.sector = chunk_to_sector(s->store, pe->e.old_chunk); 1823df96eee6SMikulas Patocka src.count = min((sector_t)s->store->chunk_size, dev_size - src.sector); 18241da177e4SLinus Torvalds 1825fc56f6fbSMike Snitzer dest.bdev = s->cow->bdev; 182671fab00aSJonathan Brassow dest.sector = chunk_to_sector(s->store, pe->e.new_chunk); 18271da177e4SLinus Torvalds dest.count = src.count; 18281da177e4SLinus Torvalds 18291da177e4SLinus Torvalds /* Hand over to kcopyd */ 1830a2f83e8bSMikulas Patocka account_start_copy(s); 1831a2d2b034SJonathan Brassow dm_kcopyd_copy(s->kcopyd_client, &src, 1, &dest, 0, copy_callback, pe); 18321da177e4SLinus Torvalds } 18331da177e4SLinus Torvalds 18344246a0b6SChristoph Hellwig static void full_bio_end_io(struct bio *bio) 1835a6e50b40SMikulas Patocka { 1836a6e50b40SMikulas Patocka void *callback_data = bio->bi_private; 1837a6e50b40SMikulas Patocka 18384e4cbee9SChristoph Hellwig dm_kcopyd_do_callback(callback_data, 0, bio->bi_status ? 1 : 0); 1839a6e50b40SMikulas Patocka } 1840a6e50b40SMikulas Patocka 1841a6e50b40SMikulas Patocka static void start_full_bio(struct dm_snap_pending_exception *pe, 1842a6e50b40SMikulas Patocka struct bio *bio) 1843a6e50b40SMikulas Patocka { 1844a6e50b40SMikulas Patocka struct dm_snapshot *s = pe->snap; 1845a6e50b40SMikulas Patocka void *callback_data; 1846a6e50b40SMikulas Patocka 1847a6e50b40SMikulas Patocka pe->full_bio = bio; 1848a6e50b40SMikulas Patocka pe->full_bio_end_io = bio->bi_end_io; 1849a6e50b40SMikulas Patocka 1850a2f83e8bSMikulas Patocka account_start_copy(s); 1851a6e50b40SMikulas Patocka callback_data = dm_kcopyd_prepare_callback(s->kcopyd_client, 1852a6e50b40SMikulas Patocka copy_callback, pe); 1853a6e50b40SMikulas Patocka 1854a6e50b40SMikulas Patocka bio->bi_end_io = full_bio_end_io; 1855a6e50b40SMikulas Patocka bio->bi_private = callback_data; 1856a6e50b40SMikulas Patocka 1857ed00aabdSChristoph Hellwig submit_bio_noacct(bio); 1858a6e50b40SMikulas Patocka } 1859a6e50b40SMikulas Patocka 18602913808eSMikulas Patocka static struct dm_snap_pending_exception * 18612913808eSMikulas Patocka __lookup_pending_exception(struct dm_snapshot *s, chunk_t chunk) 18622913808eSMikulas Patocka { 18633510cb94SJon Brassow struct dm_exception *e = dm_lookup_exception(&s->pending, chunk); 18642913808eSMikulas Patocka 18652913808eSMikulas Patocka if (!e) 18662913808eSMikulas Patocka return NULL; 18672913808eSMikulas Patocka 18682913808eSMikulas Patocka return container_of(e, struct dm_snap_pending_exception, e); 18692913808eSMikulas Patocka } 18702913808eSMikulas Patocka 18711da177e4SLinus Torvalds /* 187265fc7c37SNikos Tsironis * Inserts a pending exception into the pending table. 187365fc7c37SNikos Tsironis * 18743f1637f2SNikos Tsironis * NOTE: a write lock must be held on the chunk's pending exception table slot 18753f1637f2SNikos Tsironis * before calling this. 187665fc7c37SNikos Tsironis */ 187765fc7c37SNikos Tsironis static struct dm_snap_pending_exception * 187865fc7c37SNikos Tsironis __insert_pending_exception(struct dm_snapshot *s, 187965fc7c37SNikos Tsironis struct dm_snap_pending_exception *pe, chunk_t chunk) 188065fc7c37SNikos Tsironis { 188165fc7c37SNikos Tsironis pe->e.old_chunk = chunk; 188265fc7c37SNikos Tsironis bio_list_init(&pe->origin_bios); 188365fc7c37SNikos Tsironis bio_list_init(&pe->snapshot_bios); 188465fc7c37SNikos Tsironis pe->started = 0; 188565fc7c37SNikos Tsironis pe->full_bio = NULL; 188665fc7c37SNikos Tsironis 18873f1637f2SNikos Tsironis spin_lock(&s->pe_allocation_lock); 188865fc7c37SNikos Tsironis if (s->store->type->prepare_exception(s->store, &pe->e)) { 18893f1637f2SNikos Tsironis spin_unlock(&s->pe_allocation_lock); 189065fc7c37SNikos Tsironis free_pending_exception(pe); 189165fc7c37SNikos Tsironis return NULL; 189265fc7c37SNikos Tsironis } 189365fc7c37SNikos Tsironis 189465fc7c37SNikos Tsironis pe->exception_sequence = s->exception_start_sequence++; 18953f1637f2SNikos Tsironis spin_unlock(&s->pe_allocation_lock); 189665fc7c37SNikos Tsironis 189765fc7c37SNikos Tsironis dm_insert_exception(&s->pending, &pe->e); 189865fc7c37SNikos Tsironis 189965fc7c37SNikos Tsironis return pe; 190065fc7c37SNikos Tsironis } 190165fc7c37SNikos Tsironis 190265fc7c37SNikos Tsironis /* 19031da177e4SLinus Torvalds * Looks to see if this snapshot already has a pending exception 19041da177e4SLinus Torvalds * for this chunk, otherwise it allocates a new one and inserts 19051da177e4SLinus Torvalds * it into the pending table. 19061da177e4SLinus Torvalds * 19073f1637f2SNikos Tsironis * NOTE: a write lock must be held on the chunk's pending exception table slot 19083f1637f2SNikos Tsironis * before calling this. 19091da177e4SLinus Torvalds */ 1910028867acSAlasdair G Kergon static struct dm_snap_pending_exception * 1911c6621392SMikulas Patocka __find_pending_exception(struct dm_snapshot *s, 1912c6621392SMikulas Patocka struct dm_snap_pending_exception *pe, chunk_t chunk) 19131da177e4SLinus Torvalds { 1914c6621392SMikulas Patocka struct dm_snap_pending_exception *pe2; 191576df1c65SAlasdair G Kergon 19162913808eSMikulas Patocka pe2 = __lookup_pending_exception(s, chunk); 19172913808eSMikulas Patocka if (pe2) { 19181da177e4SLinus Torvalds free_pending_exception(pe); 19192913808eSMikulas Patocka return pe2; 192076df1c65SAlasdair G Kergon } 192176df1c65SAlasdair G Kergon 192265fc7c37SNikos Tsironis return __insert_pending_exception(s, pe, chunk); 19231da177e4SLinus Torvalds } 19241da177e4SLinus Torvalds 19251d4989c8SJon Brassow static void remap_exception(struct dm_snapshot *s, struct dm_exception *e, 1926d74f81f8SMilan Broz struct bio *bio, chunk_t chunk) 19271da177e4SLinus Torvalds { 192874d46992SChristoph Hellwig bio_set_dev(bio, s->cow->bdev); 19294f024f37SKent Overstreet bio->bi_iter.bi_sector = 19304f024f37SKent Overstreet chunk_to_sector(s->store, dm_chunk_number(e->new_chunk) + 1931d74f81f8SMilan Broz (chunk - e->old_chunk)) + 19324f024f37SKent Overstreet (bio->bi_iter.bi_sector & s->store->chunk_mask); 19331da177e4SLinus Torvalds } 19341da177e4SLinus Torvalds 19352e602385SMike Snitzer static void zero_callback(int read_err, unsigned long write_err, void *context) 19362e602385SMike Snitzer { 19372e602385SMike Snitzer struct bio *bio = context; 19382e602385SMike Snitzer struct dm_snapshot *s = bio->bi_private; 19392e602385SMike Snitzer 1940a2f83e8bSMikulas Patocka account_end_copy(s); 19412e602385SMike Snitzer bio->bi_status = write_err ? BLK_STS_IOERR : 0; 19422e602385SMike Snitzer bio_endio(bio); 19432e602385SMike Snitzer } 19442e602385SMike Snitzer 19452e602385SMike Snitzer static void zero_exception(struct dm_snapshot *s, struct dm_exception *e, 19462e602385SMike Snitzer struct bio *bio, chunk_t chunk) 19472e602385SMike Snitzer { 19482e602385SMike Snitzer struct dm_io_region dest; 19492e602385SMike Snitzer 19502e602385SMike Snitzer dest.bdev = s->cow->bdev; 19512e602385SMike Snitzer dest.sector = bio->bi_iter.bi_sector; 19522e602385SMike Snitzer dest.count = s->store->chunk_size; 19532e602385SMike Snitzer 1954a2f83e8bSMikulas Patocka account_start_copy(s); 19552e602385SMike Snitzer WARN_ON_ONCE(bio->bi_private); 19562e602385SMike Snitzer bio->bi_private = s; 19572e602385SMike Snitzer dm_kcopyd_zero(s->kcopyd_client, 1, &dest, 0, zero_callback, bio); 19582e602385SMike Snitzer } 19592e602385SMike Snitzer 19602e602385SMike Snitzer static bool io_overlaps_chunk(struct dm_snapshot *s, struct bio *bio) 19612e602385SMike Snitzer { 19622e602385SMike Snitzer return bio->bi_iter.bi_size == 19632e602385SMike Snitzer (s->store->chunk_size << SECTOR_SHIFT); 19642e602385SMike Snitzer } 19652e602385SMike Snitzer 19667de3ee57SMikulas Patocka static int snapshot_map(struct dm_target *ti, struct bio *bio) 19671da177e4SLinus Torvalds { 19681d4989c8SJon Brassow struct dm_exception *e; 1969028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 1970d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED; 19711da177e4SLinus Torvalds chunk_t chunk; 1972028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = NULL; 1973f79ae415SNikos Tsironis struct dm_exception_table_lock lock; 19741da177e4SLinus Torvalds 1975ee18026aSMikulas Patocka init_tracked_chunk(bio); 1976ee18026aSMikulas Patocka 19771eff9d32SJens Axboe if (bio->bi_opf & REQ_PREFLUSH) { 197874d46992SChristoph Hellwig bio_set_dev(bio, s->cow->bdev); 1979494b3ee7SMikulas Patocka return DM_MAPIO_REMAPPED; 1980494b3ee7SMikulas Patocka } 1981494b3ee7SMikulas Patocka 19824f024f37SKent Overstreet chunk = sector_to_chunk(s->store, bio->bi_iter.bi_sector); 1983f79ae415SNikos Tsironis dm_exception_table_lock_init(s, chunk, &lock); 19841da177e4SLinus Torvalds 19851da177e4SLinus Torvalds /* Full snapshots are not usable */ 198676df1c65SAlasdair G Kergon /* To get here the table must be live so s->active is always set. */ 19871da177e4SLinus Torvalds if (!s->valid) 1988846785e6SChristoph Hellwig return DM_MAPIO_KILL; 19891da177e4SLinus Torvalds 1990b2155578SMikulas Patocka if (bio_data_dir(bio) == WRITE) { 1991b2155578SMikulas Patocka while (unlikely(!wait_for_in_progress(s, false))) 1992b2155578SMikulas Patocka ; /* wait_for_in_progress() has slept */ 1993b2155578SMikulas Patocka } 1994b2155578SMikulas Patocka 19953f1637f2SNikos Tsironis down_read(&s->lock); 1996f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 19971da177e4SLinus Torvalds 199870246286SChristoph Hellwig if (!s->valid || (unlikely(s->snapshot_overflowed) && 199970246286SChristoph Hellwig bio_data_dir(bio) == WRITE)) { 2000846785e6SChristoph Hellwig r = DM_MAPIO_KILL; 200176df1c65SAlasdair G Kergon goto out_unlock; 200276df1c65SAlasdair G Kergon } 200376df1c65SAlasdair G Kergon 20042e602385SMike Snitzer if (unlikely(bio_op(bio) == REQ_OP_DISCARD)) { 20052e602385SMike Snitzer if (s->discard_passdown_origin && dm_bio_get_target_bio_nr(bio)) { 20062e602385SMike Snitzer /* 20072e602385SMike Snitzer * passdown discard to origin (without triggering 20082e602385SMike Snitzer * snapshot exceptions via do_origin; doing so would 20092e602385SMike Snitzer * defeat the goal of freeing space in origin that is 20102e602385SMike Snitzer * implied by the "discard_passdown_origin" feature) 20112e602385SMike Snitzer */ 20122e602385SMike Snitzer bio_set_dev(bio, s->origin->bdev); 20132e602385SMike Snitzer track_chunk(s, bio, chunk); 20142e602385SMike Snitzer goto out_unlock; 20152e602385SMike Snitzer } 20162e602385SMike Snitzer /* discard to snapshot (target_bio_nr == 0) zeroes exceptions */ 20172e602385SMike Snitzer } 20182e602385SMike Snitzer 20191da177e4SLinus Torvalds /* If the block is already remapped - use that, else remap it */ 20203510cb94SJon Brassow e = dm_lookup_exception(&s->complete, chunk); 20211da177e4SLinus Torvalds if (e) { 2022d74f81f8SMilan Broz remap_exception(s, e, bio, chunk); 20232e602385SMike Snitzer if (unlikely(bio_op(bio) == REQ_OP_DISCARD) && 20242e602385SMike Snitzer io_overlaps_chunk(s, bio)) { 20252e602385SMike Snitzer dm_exception_table_unlock(&lock); 20262e602385SMike Snitzer up_read(&s->lock); 20272e602385SMike Snitzer zero_exception(s, e, bio, chunk); 20282e602385SMike Snitzer r = DM_MAPIO_SUBMITTED; /* discard is not issued */ 20292e602385SMike Snitzer goto out; 20302e602385SMike Snitzer } 20312e602385SMike Snitzer goto out_unlock; 20322e602385SMike Snitzer } 20332e602385SMike Snitzer 20342e602385SMike Snitzer if (unlikely(bio_op(bio) == REQ_OP_DISCARD)) { 20352e602385SMike Snitzer /* 20362e602385SMike Snitzer * If no exception exists, complete discard immediately 20372e602385SMike Snitzer * otherwise it'll trigger copy-out. 20382e602385SMike Snitzer */ 20392e602385SMike Snitzer bio_endio(bio); 20402e602385SMike Snitzer r = DM_MAPIO_SUBMITTED; 204176df1c65SAlasdair G Kergon goto out_unlock; 204276df1c65SAlasdair G Kergon } 20431da177e4SLinus Torvalds 2044ba40a2aaSAlasdair G Kergon /* 2045ba40a2aaSAlasdair G Kergon * Write to snapshot - higher level takes care of RW/RO 2046ba40a2aaSAlasdair G Kergon * flags so we should only get this if we are 2047ba40a2aaSAlasdair G Kergon * writeable. 2048ba40a2aaSAlasdair G Kergon */ 204970246286SChristoph Hellwig if (bio_data_dir(bio) == WRITE) { 20502913808eSMikulas Patocka pe = __lookup_pending_exception(s, chunk); 20512913808eSMikulas Patocka if (!pe) { 2052f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 2053c6621392SMikulas Patocka pe = alloc_pending_exception(s); 2054f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 2055c6621392SMikulas Patocka 20563510cb94SJon Brassow e = dm_lookup_exception(&s->complete, chunk); 205735bf659bSMikulas Patocka if (e) { 205835bf659bSMikulas Patocka free_pending_exception(pe); 205935bf659bSMikulas Patocka remap_exception(s, e, bio, chunk); 206035bf659bSMikulas Patocka goto out_unlock; 206135bf659bSMikulas Patocka } 206235bf659bSMikulas Patocka 2063c6621392SMikulas Patocka pe = __find_pending_exception(s, pe, chunk); 20641da177e4SLinus Torvalds if (!pe) { 2065f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 20663f1637f2SNikos Tsironis up_read(&s->lock); 20673f1637f2SNikos Tsironis 20683f1637f2SNikos Tsironis down_write(&s->lock); 2069f79ae415SNikos Tsironis 2070b0d3cc01SMike Snitzer if (s->store->userspace_supports_overflow) { 20713f1637f2SNikos Tsironis if (s->valid && !s->snapshot_overflowed) { 207276c44f6dSMikulas Patocka s->snapshot_overflowed = 1; 207376c44f6dSMikulas Patocka DMERR("Snapshot overflowed: Unable to allocate exception."); 20743f1637f2SNikos Tsironis } 2075b0d3cc01SMike Snitzer } else 2076b0d3cc01SMike Snitzer __invalidate_snapshot(s, -ENOMEM); 2077f79ae415SNikos Tsironis up_write(&s->lock); 2078f79ae415SNikos Tsironis 2079846785e6SChristoph Hellwig r = DM_MAPIO_KILL; 2080f79ae415SNikos Tsironis goto out; 208176df1c65SAlasdair G Kergon } 20822913808eSMikulas Patocka } 208376df1c65SAlasdair G Kergon 2084d74f81f8SMilan Broz remap_exception(s, &pe->e, bio, chunk); 20851da177e4SLinus Torvalds 2086d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 2087ba40a2aaSAlasdair G Kergon 20882e602385SMike Snitzer if (!pe->started && io_overlaps_chunk(s, bio)) { 2089a6e50b40SMikulas Patocka pe->started = 1; 20903f1637f2SNikos Tsironis 2091f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 20923f1637f2SNikos Tsironis up_read(&s->lock); 20933f1637f2SNikos Tsironis 2094a6e50b40SMikulas Patocka start_full_bio(pe, bio); 2095a6e50b40SMikulas Patocka goto out; 2096a6e50b40SMikulas Patocka } 2097a6e50b40SMikulas Patocka 2098a6e50b40SMikulas Patocka bio_list_add(&pe->snapshot_bios, bio); 2099a6e50b40SMikulas Patocka 21001da177e4SLinus Torvalds if (!pe->started) { 21013f1637f2SNikos Tsironis /* this is protected by the exception table lock */ 21021da177e4SLinus Torvalds pe->started = 1; 21033f1637f2SNikos Tsironis 2104f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 21053f1637f2SNikos Tsironis up_read(&s->lock); 21063f1637f2SNikos Tsironis 210776df1c65SAlasdair G Kergon start_copy(pe); 2108ba40a2aaSAlasdair G Kergon goto out; 2109ba40a2aaSAlasdair G Kergon } 2110cd45daffSMikulas Patocka } else { 211174d46992SChristoph Hellwig bio_set_dev(bio, s->origin->bdev); 2112ee18026aSMikulas Patocka track_chunk(s, bio, chunk); 2113cd45daffSMikulas Patocka } 21141da177e4SLinus Torvalds 2115ba40a2aaSAlasdair G Kergon out_unlock: 2116f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 21173f1637f2SNikos Tsironis up_read(&s->lock); 2118ba40a2aaSAlasdair G Kergon out: 21191da177e4SLinus Torvalds return r; 21201da177e4SLinus Torvalds } 21211da177e4SLinus Torvalds 21223452c2a1SMikulas Patocka /* 21233452c2a1SMikulas Patocka * A snapshot-merge target behaves like a combination of a snapshot 21243452c2a1SMikulas Patocka * target and a snapshot-origin target. It only generates new 21253452c2a1SMikulas Patocka * exceptions in other snapshots and not in the one that is being 21263452c2a1SMikulas Patocka * merged. 21273452c2a1SMikulas Patocka * 21283452c2a1SMikulas Patocka * For each chunk, if there is an existing exception, it is used to 21293452c2a1SMikulas Patocka * redirect I/O to the cow device. Otherwise I/O is sent to the origin, 21303452c2a1SMikulas Patocka * which in turn might generate exceptions in other snapshots. 21319fe86254SMikulas Patocka * If merging is currently taking place on the chunk in question, the 21329fe86254SMikulas Patocka * I/O is deferred by adding it to s->bios_queued_during_merge. 21333452c2a1SMikulas Patocka */ 21347de3ee57SMikulas Patocka static int snapshot_merge_map(struct dm_target *ti, struct bio *bio) 21353452c2a1SMikulas Patocka { 21363452c2a1SMikulas Patocka struct dm_exception *e; 21373452c2a1SMikulas Patocka struct dm_snapshot *s = ti->private; 21383452c2a1SMikulas Patocka int r = DM_MAPIO_REMAPPED; 21393452c2a1SMikulas Patocka chunk_t chunk; 21403452c2a1SMikulas Patocka 2141ee18026aSMikulas Patocka init_tracked_chunk(bio); 2142ee18026aSMikulas Patocka 21431eff9d32SJens Axboe if (bio->bi_opf & REQ_PREFLUSH) { 214455a62eefSAlasdair G Kergon if (!dm_bio_get_target_bio_nr(bio)) 214574d46992SChristoph Hellwig bio_set_dev(bio, s->origin->bdev); 214610b8106aSMike Snitzer else 214774d46992SChristoph Hellwig bio_set_dev(bio, s->cow->bdev); 214810b8106aSMike Snitzer return DM_MAPIO_REMAPPED; 214910b8106aSMike Snitzer } 215010b8106aSMike Snitzer 21513ee25485SMike Snitzer if (unlikely(bio_op(bio) == REQ_OP_DISCARD)) { 21523ee25485SMike Snitzer /* Once merging, discards no longer effect change */ 21533ee25485SMike Snitzer bio_endio(bio); 21543ee25485SMike Snitzer return DM_MAPIO_SUBMITTED; 21553ee25485SMike Snitzer } 21563ee25485SMike Snitzer 21574f024f37SKent Overstreet chunk = sector_to_chunk(s->store, bio->bi_iter.bi_sector); 21583452c2a1SMikulas Patocka 21594ad8d880SNikos Tsironis down_write(&s->lock); 21603452c2a1SMikulas Patocka 2161d2fdb776SMikulas Patocka /* Full merging snapshots are redirected to the origin */ 2162d2fdb776SMikulas Patocka if (!s->valid) 2163d2fdb776SMikulas Patocka goto redirect_to_origin; 21643452c2a1SMikulas Patocka 21653452c2a1SMikulas Patocka /* If the block is already remapped - use that */ 21663452c2a1SMikulas Patocka e = dm_lookup_exception(&s->complete, chunk); 21673452c2a1SMikulas Patocka if (e) { 21689fe86254SMikulas Patocka /* Queue writes overlapping with chunks being merged */ 216970246286SChristoph Hellwig if (bio_data_dir(bio) == WRITE && 21709fe86254SMikulas Patocka chunk >= s->first_merging_chunk && 21719fe86254SMikulas Patocka chunk < (s->first_merging_chunk + 21729fe86254SMikulas Patocka s->num_merging_chunks)) { 217374d46992SChristoph Hellwig bio_set_dev(bio, s->origin->bdev); 21749fe86254SMikulas Patocka bio_list_add(&s->bios_queued_during_merge, bio); 21759fe86254SMikulas Patocka r = DM_MAPIO_SUBMITTED; 21769fe86254SMikulas Patocka goto out_unlock; 21779fe86254SMikulas Patocka } 217817aa0332SMikulas Patocka 21793452c2a1SMikulas Patocka remap_exception(s, e, bio, chunk); 218017aa0332SMikulas Patocka 218170246286SChristoph Hellwig if (bio_data_dir(bio) == WRITE) 2182ee18026aSMikulas Patocka track_chunk(s, bio, chunk); 21833452c2a1SMikulas Patocka goto out_unlock; 21843452c2a1SMikulas Patocka } 21853452c2a1SMikulas Patocka 2186d2fdb776SMikulas Patocka redirect_to_origin: 218774d46992SChristoph Hellwig bio_set_dev(bio, s->origin->bdev); 21883452c2a1SMikulas Patocka 218970246286SChristoph Hellwig if (bio_data_dir(bio) == WRITE) { 21904ad8d880SNikos Tsironis up_write(&s->lock); 2191b2155578SMikulas Patocka return do_origin(s->origin, bio, false); 21923452c2a1SMikulas Patocka } 21933452c2a1SMikulas Patocka 21943452c2a1SMikulas Patocka out_unlock: 21954ad8d880SNikos Tsironis up_write(&s->lock); 21963452c2a1SMikulas Patocka 21973452c2a1SMikulas Patocka return r; 21983452c2a1SMikulas Patocka } 21993452c2a1SMikulas Patocka 22004e4cbee9SChristoph Hellwig static int snapshot_end_io(struct dm_target *ti, struct bio *bio, 22014e4cbee9SChristoph Hellwig blk_status_t *error) 2202cd45daffSMikulas Patocka { 2203cd45daffSMikulas Patocka struct dm_snapshot *s = ti->private; 2204cd45daffSMikulas Patocka 2205ee18026aSMikulas Patocka if (is_bio_tracked(bio)) 2206ee18026aSMikulas Patocka stop_tracking_chunk(s, bio); 2207cd45daffSMikulas Patocka 22081be56909SChristoph Hellwig return DM_ENDIO_DONE; 2209cd45daffSMikulas Patocka } 2210cd45daffSMikulas Patocka 22111e03f97eSMikulas Patocka static void snapshot_merge_presuspend(struct dm_target *ti) 22121e03f97eSMikulas Patocka { 22131e03f97eSMikulas Patocka struct dm_snapshot *s = ti->private; 22141e03f97eSMikulas Patocka 22151e03f97eSMikulas Patocka stop_merge(s); 22161e03f97eSMikulas Patocka } 22171e03f97eSMikulas Patocka 2218c1f0c183SMike Snitzer static int snapshot_preresume(struct dm_target *ti) 2219c1f0c183SMike Snitzer { 2220c1f0c183SMike Snitzer int r = 0; 2221c1f0c183SMike Snitzer struct dm_snapshot *s = ti->private; 2222c1f0c183SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 2223c1f0c183SMike Snitzer 2224c1f0c183SMike Snitzer down_read(&_origins_lock); 22259d3b15c4SMikulas Patocka (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); 2226c1f0c183SMike Snitzer if (snap_src && snap_dest) { 22274ad8d880SNikos Tsironis down_read(&snap_src->lock); 2228c1f0c183SMike Snitzer if (s == snap_src) { 2229c1f0c183SMike Snitzer DMERR("Unable to resume snapshot source until " 2230c1f0c183SMike Snitzer "handover completes."); 2231c1f0c183SMike Snitzer r = -EINVAL; 2232b83b2f29SMike Snitzer } else if (!dm_suspended(snap_src->ti)) { 2233c1f0c183SMike Snitzer DMERR("Unable to perform snapshot handover until " 2234c1f0c183SMike Snitzer "source is suspended."); 2235c1f0c183SMike Snitzer r = -EINVAL; 2236c1f0c183SMike Snitzer } 22374ad8d880SNikos Tsironis up_read(&snap_src->lock); 2238c1f0c183SMike Snitzer } 2239c1f0c183SMike Snitzer up_read(&_origins_lock); 2240c1f0c183SMike Snitzer 2241c1f0c183SMike Snitzer return r; 2242c1f0c183SMike Snitzer } 2243c1f0c183SMike Snitzer 22441da177e4SLinus Torvalds static void snapshot_resume(struct dm_target *ti) 22451da177e4SLinus Torvalds { 2246028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 224709ee96b2SMikulas Patocka struct dm_snapshot *snap_src = NULL, *snap_dest = NULL, *snap_merging = NULL; 2248b735fedeSMikulas Patocka struct dm_origin *o; 2249b735fedeSMikulas Patocka struct mapped_device *origin_md = NULL; 225009ee96b2SMikulas Patocka bool must_restart_merging = false; 2251c1f0c183SMike Snitzer 2252c1f0c183SMike Snitzer down_read(&_origins_lock); 2253b735fedeSMikulas Patocka 2254b735fedeSMikulas Patocka o = __lookup_dm_origin(s->origin->bdev); 2255b735fedeSMikulas Patocka if (o) 2256b735fedeSMikulas Patocka origin_md = dm_table_get_md(o->ti->table); 225709ee96b2SMikulas Patocka if (!origin_md) { 225809ee96b2SMikulas Patocka (void) __find_snapshots_sharing_cow(s, NULL, NULL, &snap_merging); 225909ee96b2SMikulas Patocka if (snap_merging) 226009ee96b2SMikulas Patocka origin_md = dm_table_get_md(snap_merging->ti->table); 226109ee96b2SMikulas Patocka } 2262b735fedeSMikulas Patocka if (origin_md == dm_table_get_md(ti->table)) 2263b735fedeSMikulas Patocka origin_md = NULL; 226409ee96b2SMikulas Patocka if (origin_md) { 226509ee96b2SMikulas Patocka if (dm_hold(origin_md)) 226609ee96b2SMikulas Patocka origin_md = NULL; 226709ee96b2SMikulas Patocka } 2268b735fedeSMikulas Patocka 226909ee96b2SMikulas Patocka up_read(&_origins_lock); 227009ee96b2SMikulas Patocka 227109ee96b2SMikulas Patocka if (origin_md) { 2272b735fedeSMikulas Patocka dm_internal_suspend_fast(origin_md); 227309ee96b2SMikulas Patocka if (snap_merging && test_bit(RUNNING_MERGE, &snap_merging->state_bits)) { 227409ee96b2SMikulas Patocka must_restart_merging = true; 227509ee96b2SMikulas Patocka stop_merge(snap_merging); 227609ee96b2SMikulas Patocka } 227709ee96b2SMikulas Patocka } 227809ee96b2SMikulas Patocka 227909ee96b2SMikulas Patocka down_read(&_origins_lock); 2280b735fedeSMikulas Patocka 22819d3b15c4SMikulas Patocka (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); 2282c1f0c183SMike Snitzer if (snap_src && snap_dest) { 22834ad8d880SNikos Tsironis down_write(&snap_src->lock); 22844ad8d880SNikos Tsironis down_write_nested(&snap_dest->lock, SINGLE_DEPTH_NESTING); 2285c1f0c183SMike Snitzer __handover_exceptions(snap_src, snap_dest); 22864ad8d880SNikos Tsironis up_write(&snap_dest->lock); 22874ad8d880SNikos Tsironis up_write(&snap_src->lock); 2288c1f0c183SMike Snitzer } 2289b735fedeSMikulas Patocka 2290c1f0c183SMike Snitzer up_read(&_origins_lock); 2291c1f0c183SMike Snitzer 229209ee96b2SMikulas Patocka if (origin_md) { 229309ee96b2SMikulas Patocka if (must_restart_merging) 229409ee96b2SMikulas Patocka start_merge(snap_merging); 229509ee96b2SMikulas Patocka dm_internal_resume_fast(origin_md); 229609ee96b2SMikulas Patocka dm_put(origin_md); 229709ee96b2SMikulas Patocka } 229809ee96b2SMikulas Patocka 2299c1f0c183SMike Snitzer /* Now we have correct chunk size, reregister */ 2300c1f0c183SMike Snitzer reregister_snapshot(s); 23011da177e4SLinus Torvalds 23024ad8d880SNikos Tsironis down_write(&s->lock); 2303aa14edebSAlasdair G Kergon s->active = 1; 23044ad8d880SNikos Tsironis up_write(&s->lock); 23051da177e4SLinus Torvalds } 23061da177e4SLinus Torvalds 2307542f9038SMike Snitzer static uint32_t get_origin_minimum_chunksize(struct block_device *bdev) 23081e03f97eSMikulas Patocka { 2309542f9038SMike Snitzer uint32_t min_chunksize; 23101e03f97eSMikulas Patocka 23111e03f97eSMikulas Patocka down_read(&_origins_lock); 23121e03f97eSMikulas Patocka min_chunksize = __minimum_chunk_size(__lookup_origin(bdev)); 23131e03f97eSMikulas Patocka up_read(&_origins_lock); 23141e03f97eSMikulas Patocka 23151e03f97eSMikulas Patocka return min_chunksize; 23161e03f97eSMikulas Patocka } 23171e03f97eSMikulas Patocka 23181e03f97eSMikulas Patocka static void snapshot_merge_resume(struct dm_target *ti) 23191e03f97eSMikulas Patocka { 23201e03f97eSMikulas Patocka struct dm_snapshot *s = ti->private; 23211e03f97eSMikulas Patocka 23221e03f97eSMikulas Patocka /* 23231e03f97eSMikulas Patocka * Handover exceptions from existing snapshot. 23241e03f97eSMikulas Patocka */ 23251e03f97eSMikulas Patocka snapshot_resume(ti); 23261e03f97eSMikulas Patocka 23271e03f97eSMikulas Patocka /* 2328542f9038SMike Snitzer * snapshot-merge acts as an origin, so set ti->max_io_len 23291e03f97eSMikulas Patocka */ 2330542f9038SMike Snitzer ti->max_io_len = get_origin_minimum_chunksize(s->origin->bdev); 23311e03f97eSMikulas Patocka 23321e03f97eSMikulas Patocka start_merge(s); 23331e03f97eSMikulas Patocka } 23341e03f97eSMikulas Patocka 2335fd7c092eSMikulas Patocka static void snapshot_status(struct dm_target *ti, status_type_t type, 23361f4e0ff0SAlasdair G Kergon unsigned status_flags, char *result, unsigned maxlen) 23371da177e4SLinus Torvalds { 23382e4a31dfSJonathan Brassow unsigned sz = 0; 2339028867acSAlasdair G Kergon struct dm_snapshot *snap = ti->private; 23402e602385SMike Snitzer unsigned num_features; 23411da177e4SLinus Torvalds 23421da177e4SLinus Torvalds switch (type) { 23431da177e4SLinus Torvalds case STATUSTYPE_INFO: 234494e76572SMikulas Patocka 23454ad8d880SNikos Tsironis down_write(&snap->lock); 234694e76572SMikulas Patocka 23471da177e4SLinus Torvalds if (!snap->valid) 23482e4a31dfSJonathan Brassow DMEMIT("Invalid"); 2349d8ddb1cfSMike Snitzer else if (snap->merge_failed) 2350d8ddb1cfSMike Snitzer DMEMIT("Merge failed"); 235176c44f6dSMikulas Patocka else if (snap->snapshot_overflowed) 235276c44f6dSMikulas Patocka DMEMIT("Overflow"); 23531da177e4SLinus Torvalds else { 2354985903bbSMike Snitzer if (snap->store->type->usage) { 2355985903bbSMike Snitzer sector_t total_sectors, sectors_allocated, 2356985903bbSMike Snitzer metadata_sectors; 2357985903bbSMike Snitzer snap->store->type->usage(snap->store, 2358985903bbSMike Snitzer &total_sectors, 2359985903bbSMike Snitzer §ors_allocated, 2360985903bbSMike Snitzer &metadata_sectors); 2361985903bbSMike Snitzer DMEMIT("%llu/%llu %llu", 2362985903bbSMike Snitzer (unsigned long long)sectors_allocated, 2363985903bbSMike Snitzer (unsigned long long)total_sectors, 2364985903bbSMike Snitzer (unsigned long long)metadata_sectors); 23651da177e4SLinus Torvalds } 23661da177e4SLinus Torvalds else 23672e4a31dfSJonathan Brassow DMEMIT("Unknown"); 23681da177e4SLinus Torvalds } 236994e76572SMikulas Patocka 23704ad8d880SNikos Tsironis up_write(&snap->lock); 237194e76572SMikulas Patocka 23721da177e4SLinus Torvalds break; 23731da177e4SLinus Torvalds 23741da177e4SLinus Torvalds case STATUSTYPE_TABLE: 23751da177e4SLinus Torvalds /* 23761da177e4SLinus Torvalds * kdevname returns a static pointer so we need 23771da177e4SLinus Torvalds * to make private copies if the output is to 23781da177e4SLinus Torvalds * make sense. 23791da177e4SLinus Torvalds */ 2380fc56f6fbSMike Snitzer DMEMIT("%s %s", snap->origin->name, snap->cow->name); 23812e602385SMike Snitzer sz += snap->store->type->status(snap->store, type, result + sz, 23821e302a92SJonathan Brassow maxlen - sz); 23832e602385SMike Snitzer num_features = snap->discard_zeroes_cow + snap->discard_passdown_origin; 23842e602385SMike Snitzer if (num_features) { 23852e602385SMike Snitzer DMEMIT(" %u", num_features); 23862e602385SMike Snitzer if (snap->discard_zeroes_cow) 23872e602385SMike Snitzer DMEMIT(" discard_zeroes_cow"); 23882e602385SMike Snitzer if (snap->discard_passdown_origin) 23892e602385SMike Snitzer DMEMIT(" discard_passdown_origin"); 23902e602385SMike Snitzer } 23911da177e4SLinus Torvalds break; 23921da177e4SLinus Torvalds } 23931da177e4SLinus Torvalds } 23941da177e4SLinus Torvalds 23958811f46cSMike Snitzer static int snapshot_iterate_devices(struct dm_target *ti, 23968811f46cSMike Snitzer iterate_devices_callout_fn fn, void *data) 23978811f46cSMike Snitzer { 23988811f46cSMike Snitzer struct dm_snapshot *snap = ti->private; 23991e5554c8SMikulas Patocka int r; 24008811f46cSMike Snitzer 24011e5554c8SMikulas Patocka r = fn(ti, snap->origin, 0, ti->len, data); 24021e5554c8SMikulas Patocka 24031e5554c8SMikulas Patocka if (!r) 24041e5554c8SMikulas Patocka r = fn(ti, snap->cow, 0, get_dev_size(snap->cow->bdev), data); 24051e5554c8SMikulas Patocka 24061e5554c8SMikulas Patocka return r; 24078811f46cSMike Snitzer } 24088811f46cSMike Snitzer 24092e602385SMike Snitzer static void snapshot_io_hints(struct dm_target *ti, struct queue_limits *limits) 24102e602385SMike Snitzer { 24112e602385SMike Snitzer struct dm_snapshot *snap = ti->private; 24122e602385SMike Snitzer 24132e602385SMike Snitzer if (snap->discard_zeroes_cow) { 24142e602385SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 24152e602385SMike Snitzer 24163ee25485SMike Snitzer down_read(&_origins_lock); 24173ee25485SMike Snitzer 24182e602385SMike Snitzer (void) __find_snapshots_sharing_cow(snap, &snap_src, &snap_dest, NULL); 24192e602385SMike Snitzer if (snap_src && snap_dest) 24202e602385SMike Snitzer snap = snap_src; 24212e602385SMike Snitzer 24222e602385SMike Snitzer /* All discards are split on chunk_size boundary */ 24232e602385SMike Snitzer limits->discard_granularity = snap->store->chunk_size; 24242e602385SMike Snitzer limits->max_discard_sectors = snap->store->chunk_size; 24253ee25485SMike Snitzer 24263ee25485SMike Snitzer up_read(&_origins_lock); 24272e602385SMike Snitzer } 24282e602385SMike Snitzer } 24298811f46cSMike Snitzer 24301da177e4SLinus Torvalds /*----------------------------------------------------------------- 24311da177e4SLinus Torvalds * Origin methods 24321da177e4SLinus Torvalds *---------------------------------------------------------------*/ 24339eaae8ffSMikulas Patocka 24349eaae8ffSMikulas Patocka /* 24359eaae8ffSMikulas Patocka * If no exceptions need creating, DM_MAPIO_REMAPPED is returned and any 24369eaae8ffSMikulas Patocka * supplied bio was ignored. The caller may submit it immediately. 24379eaae8ffSMikulas Patocka * (No remapping actually occurs as the origin is always a direct linear 24389eaae8ffSMikulas Patocka * map.) 24399eaae8ffSMikulas Patocka * 24409eaae8ffSMikulas Patocka * If further exceptions are required, DM_MAPIO_SUBMITTED is returned 24419eaae8ffSMikulas Patocka * and any supplied bio is added to a list to be submitted once all 24429eaae8ffSMikulas Patocka * the necessary exceptions exist. 24439eaae8ffSMikulas Patocka */ 24449eaae8ffSMikulas Patocka static int __origin_write(struct list_head *snapshots, sector_t sector, 24459eaae8ffSMikulas Patocka struct bio *bio) 24461da177e4SLinus Torvalds { 2447515ad66cSMikulas Patocka int r = DM_MAPIO_REMAPPED; 24481da177e4SLinus Torvalds struct dm_snapshot *snap; 24491d4989c8SJon Brassow struct dm_exception *e; 245065fc7c37SNikos Tsironis struct dm_snap_pending_exception *pe, *pe2; 2451515ad66cSMikulas Patocka struct dm_snap_pending_exception *pe_to_start_now = NULL; 2452515ad66cSMikulas Patocka struct dm_snap_pending_exception *pe_to_start_last = NULL; 2453f79ae415SNikos Tsironis struct dm_exception_table_lock lock; 24541da177e4SLinus Torvalds chunk_t chunk; 24551da177e4SLinus Torvalds 24561da177e4SLinus Torvalds /* Do all the snapshots on this origin */ 24571da177e4SLinus Torvalds list_for_each_entry (snap, snapshots, list) { 24583452c2a1SMikulas Patocka /* 24593452c2a1SMikulas Patocka * Don't make new exceptions in a merging snapshot 24603452c2a1SMikulas Patocka * because it has effectively been deleted 24613452c2a1SMikulas Patocka */ 24623452c2a1SMikulas Patocka if (dm_target_is_snapshot_merge(snap->ti)) 24633452c2a1SMikulas Patocka continue; 24643452c2a1SMikulas Patocka 2465d5e404c1SAlasdair G Kergon /* Nothing to do if writing beyond end of snapshot */ 24669eaae8ffSMikulas Patocka if (sector >= dm_table_get_size(snap->ti->table)) 2467f79ae415SNikos Tsironis continue; 24681da177e4SLinus Torvalds 24691da177e4SLinus Torvalds /* 24701da177e4SLinus Torvalds * Remember, different snapshots can have 24711da177e4SLinus Torvalds * different chunk sizes. 24721da177e4SLinus Torvalds */ 24739eaae8ffSMikulas Patocka chunk = sector_to_chunk(snap->store, sector); 2474f79ae415SNikos Tsironis dm_exception_table_lock_init(snap, chunk, &lock); 2475f79ae415SNikos Tsironis 24763f1637f2SNikos Tsironis down_read(&snap->lock); 2477f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 2478f79ae415SNikos Tsironis 2479f79ae415SNikos Tsironis /* Only deal with valid and active snapshots */ 2480f79ae415SNikos Tsironis if (!snap->valid || !snap->active) 2481f79ae415SNikos Tsironis goto next_snapshot; 24821da177e4SLinus Torvalds 248365fc7c37SNikos Tsironis pe = __lookup_pending_exception(snap, chunk); 248465fc7c37SNikos Tsironis if (!pe) { 24851da177e4SLinus Torvalds /* 248665fc7c37SNikos Tsironis * Check exception table to see if block is already 248765fc7c37SNikos Tsironis * remapped in this snapshot and trigger an exception 248865fc7c37SNikos Tsironis * if not. 24891da177e4SLinus Torvalds */ 24903510cb94SJon Brassow e = dm_lookup_exception(&snap->complete, chunk); 249176df1c65SAlasdair G Kergon if (e) 249276df1c65SAlasdair G Kergon goto next_snapshot; 249376df1c65SAlasdair G Kergon 2494f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 2495c6621392SMikulas Patocka pe = alloc_pending_exception(snap); 2496f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 2497c6621392SMikulas Patocka 249865fc7c37SNikos Tsironis pe2 = __lookup_pending_exception(snap, chunk); 249965fc7c37SNikos Tsironis 250065fc7c37SNikos Tsironis if (!pe2) { 25013510cb94SJon Brassow e = dm_lookup_exception(&snap->complete, chunk); 250235bf659bSMikulas Patocka if (e) { 250335bf659bSMikulas Patocka free_pending_exception(pe); 250435bf659bSMikulas Patocka goto next_snapshot; 250535bf659bSMikulas Patocka } 250635bf659bSMikulas Patocka 250765fc7c37SNikos Tsironis pe = __insert_pending_exception(snap, pe, chunk); 25081da177e4SLinus Torvalds if (!pe) { 2509f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 25103f1637f2SNikos Tsironis up_read(&snap->lock); 2511f79ae415SNikos Tsironis 25123f1637f2SNikos Tsironis invalidate_snapshot(snap, -ENOMEM); 2513f79ae415SNikos Tsironis continue; 251476df1c65SAlasdair G Kergon } 251565fc7c37SNikos Tsironis } else { 251665fc7c37SNikos Tsironis free_pending_exception(pe); 251765fc7c37SNikos Tsironis pe = pe2; 251865fc7c37SNikos Tsironis } 25192913808eSMikulas Patocka } 25201da177e4SLinus Torvalds 2521d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 252276df1c65SAlasdair G Kergon 2523515ad66cSMikulas Patocka /* 2524515ad66cSMikulas Patocka * If an origin bio was supplied, queue it to wait for the 2525515ad66cSMikulas Patocka * completion of this exception, and start this one last, 2526515ad66cSMikulas Patocka * at the end of the function. 2527515ad66cSMikulas Patocka */ 2528515ad66cSMikulas Patocka if (bio) { 2529515ad66cSMikulas Patocka bio_list_add(&pe->origin_bios, bio); 2530515ad66cSMikulas Patocka bio = NULL; 2531515ad66cSMikulas Patocka 2532515ad66cSMikulas Patocka if (!pe->started) { 2533515ad66cSMikulas Patocka pe->started = 1; 2534515ad66cSMikulas Patocka pe_to_start_last = pe; 2535515ad66cSMikulas Patocka } 2536b4b610f6SAlasdair G Kergon } 253776df1c65SAlasdair G Kergon 2538eccf0817SAlasdair G Kergon if (!pe->started) { 2539eccf0817SAlasdair G Kergon pe->started = 1; 2540515ad66cSMikulas Patocka pe_to_start_now = pe; 2541eccf0817SAlasdair G Kergon } 25421da177e4SLinus Torvalds 254376df1c65SAlasdair G Kergon next_snapshot: 2544f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 25453f1637f2SNikos Tsironis up_read(&snap->lock); 2546515ad66cSMikulas Patocka 2547515ad66cSMikulas Patocka if (pe_to_start_now) { 2548515ad66cSMikulas Patocka start_copy(pe_to_start_now); 2549515ad66cSMikulas Patocka pe_to_start_now = NULL; 25501da177e4SLinus Torvalds } 2551b4b610f6SAlasdair G Kergon } 2552b4b610f6SAlasdair G Kergon 25531da177e4SLinus Torvalds /* 2554515ad66cSMikulas Patocka * Submit the exception against which the bio is queued last, 2555515ad66cSMikulas Patocka * to give the other exceptions a head start. 25561da177e4SLinus Torvalds */ 2557515ad66cSMikulas Patocka if (pe_to_start_last) 2558515ad66cSMikulas Patocka start_copy(pe_to_start_last); 25591da177e4SLinus Torvalds 25601da177e4SLinus Torvalds return r; 25611da177e4SLinus Torvalds } 25621da177e4SLinus Torvalds 25631da177e4SLinus Torvalds /* 25641da177e4SLinus Torvalds * Called on a write from the origin driver. 25651da177e4SLinus Torvalds */ 2566b2155578SMikulas Patocka static int do_origin(struct dm_dev *origin, struct bio *bio, bool limit) 25671da177e4SLinus Torvalds { 25681da177e4SLinus Torvalds struct origin *o; 2569d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED; 25701da177e4SLinus Torvalds 2571b2155578SMikulas Patocka again: 25721da177e4SLinus Torvalds down_read(&_origins_lock); 25731da177e4SLinus Torvalds o = __lookup_origin(origin->bdev); 2574b2155578SMikulas Patocka if (o) { 2575b2155578SMikulas Patocka if (limit) { 2576b2155578SMikulas Patocka struct dm_snapshot *s; 2577b2155578SMikulas Patocka list_for_each_entry(s, &o->snapshots, list) 2578b2155578SMikulas Patocka if (unlikely(!wait_for_in_progress(s, true))) 2579b2155578SMikulas Patocka goto again; 2580b2155578SMikulas Patocka } 2581b2155578SMikulas Patocka 25824f024f37SKent Overstreet r = __origin_write(&o->snapshots, bio->bi_iter.bi_sector, bio); 2583b2155578SMikulas Patocka } 25841da177e4SLinus Torvalds up_read(&_origins_lock); 25851da177e4SLinus Torvalds 25861da177e4SLinus Torvalds return r; 25871da177e4SLinus Torvalds } 25881da177e4SLinus Torvalds 25891da177e4SLinus Torvalds /* 259073dfd078SMikulas Patocka * Trigger exceptions in all non-merging snapshots. 259173dfd078SMikulas Patocka * 259273dfd078SMikulas Patocka * The chunk size of the merging snapshot may be larger than the chunk 259373dfd078SMikulas Patocka * size of some other snapshot so we may need to reallocate multiple 259473dfd078SMikulas Patocka * chunks in other snapshots. 259573dfd078SMikulas Patocka * 259673dfd078SMikulas Patocka * We scan all the overlapping exceptions in the other snapshots. 259773dfd078SMikulas Patocka * Returns 1 if anything was reallocated and must be waited for, 259873dfd078SMikulas Patocka * otherwise returns 0. 259973dfd078SMikulas Patocka * 260073dfd078SMikulas Patocka * size must be a multiple of merging_snap's chunk_size. 260173dfd078SMikulas Patocka */ 260273dfd078SMikulas Patocka static int origin_write_extent(struct dm_snapshot *merging_snap, 260373dfd078SMikulas Patocka sector_t sector, unsigned size) 260473dfd078SMikulas Patocka { 260573dfd078SMikulas Patocka int must_wait = 0; 260673dfd078SMikulas Patocka sector_t n; 260773dfd078SMikulas Patocka struct origin *o; 260873dfd078SMikulas Patocka 260973dfd078SMikulas Patocka /* 2610542f9038SMike Snitzer * The origin's __minimum_chunk_size() got stored in max_io_len 261173dfd078SMikulas Patocka * by snapshot_merge_resume(). 261273dfd078SMikulas Patocka */ 261373dfd078SMikulas Patocka down_read(&_origins_lock); 261473dfd078SMikulas Patocka o = __lookup_origin(merging_snap->origin->bdev); 2615542f9038SMike Snitzer for (n = 0; n < size; n += merging_snap->ti->max_io_len) 261673dfd078SMikulas Patocka if (__origin_write(&o->snapshots, sector + n, NULL) == 261773dfd078SMikulas Patocka DM_MAPIO_SUBMITTED) 261873dfd078SMikulas Patocka must_wait = 1; 261973dfd078SMikulas Patocka up_read(&_origins_lock); 262073dfd078SMikulas Patocka 262173dfd078SMikulas Patocka return must_wait; 262273dfd078SMikulas Patocka } 262373dfd078SMikulas Patocka 262473dfd078SMikulas Patocka /* 26251da177e4SLinus Torvalds * Origin: maps a linear range of a device, with hooks for snapshotting. 26261da177e4SLinus Torvalds */ 26271da177e4SLinus Torvalds 26281da177e4SLinus Torvalds /* 26291da177e4SLinus Torvalds * Construct an origin mapping: <dev_path> 26301da177e4SLinus Torvalds * The context for an origin is merely a 'struct dm_dev *' 26311da177e4SLinus Torvalds * pointing to the real device. 26321da177e4SLinus Torvalds */ 26331da177e4SLinus Torvalds static int origin_ctr(struct dm_target *ti, unsigned int argc, char **argv) 26341da177e4SLinus Torvalds { 26351da177e4SLinus Torvalds int r; 2636599cdf3bSMikulas Patocka struct dm_origin *o; 26371da177e4SLinus Torvalds 26381da177e4SLinus Torvalds if (argc != 1) { 263972d94861SAlasdair G Kergon ti->error = "origin: incorrect number of arguments"; 26401da177e4SLinus Torvalds return -EINVAL; 26411da177e4SLinus Torvalds } 26421da177e4SLinus Torvalds 2643599cdf3bSMikulas Patocka o = kmalloc(sizeof(struct dm_origin), GFP_KERNEL); 2644599cdf3bSMikulas Patocka if (!o) { 2645599cdf3bSMikulas Patocka ti->error = "Cannot allocate private origin structure"; 2646599cdf3bSMikulas Patocka r = -ENOMEM; 2647599cdf3bSMikulas Patocka goto bad_alloc; 26481da177e4SLinus Torvalds } 26491da177e4SLinus Torvalds 2650599cdf3bSMikulas Patocka r = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &o->dev); 2651599cdf3bSMikulas Patocka if (r) { 2652599cdf3bSMikulas Patocka ti->error = "Cannot get target device"; 2653599cdf3bSMikulas Patocka goto bad_open; 2654599cdf3bSMikulas Patocka } 2655599cdf3bSMikulas Patocka 2656b735fedeSMikulas Patocka o->ti = ti; 2657599cdf3bSMikulas Patocka ti->private = o; 265855a62eefSAlasdair G Kergon ti->num_flush_bios = 1; 2659494b3ee7SMikulas Patocka 26601da177e4SLinus Torvalds return 0; 2661599cdf3bSMikulas Patocka 2662599cdf3bSMikulas Patocka bad_open: 2663599cdf3bSMikulas Patocka kfree(o); 2664599cdf3bSMikulas Patocka bad_alloc: 2665599cdf3bSMikulas Patocka return r; 26661da177e4SLinus Torvalds } 26671da177e4SLinus Torvalds 26681da177e4SLinus Torvalds static void origin_dtr(struct dm_target *ti) 26691da177e4SLinus Torvalds { 2670599cdf3bSMikulas Patocka struct dm_origin *o = ti->private; 2671b735fedeSMikulas Patocka 2672599cdf3bSMikulas Patocka dm_put_device(ti, o->dev); 2673599cdf3bSMikulas Patocka kfree(o); 26741da177e4SLinus Torvalds } 26751da177e4SLinus Torvalds 26767de3ee57SMikulas Patocka static int origin_map(struct dm_target *ti, struct bio *bio) 26771da177e4SLinus Torvalds { 2678599cdf3bSMikulas Patocka struct dm_origin *o = ti->private; 2679298eaa89SMikulas Patocka unsigned available_sectors; 26801da177e4SLinus Torvalds 268174d46992SChristoph Hellwig bio_set_dev(bio, o->dev->bdev); 26821da177e4SLinus Torvalds 26831eff9d32SJens Axboe if (unlikely(bio->bi_opf & REQ_PREFLUSH)) 2684494b3ee7SMikulas Patocka return DM_MAPIO_REMAPPED; 2685494b3ee7SMikulas Patocka 268670246286SChristoph Hellwig if (bio_data_dir(bio) != WRITE) 2687298eaa89SMikulas Patocka return DM_MAPIO_REMAPPED; 2688298eaa89SMikulas Patocka 2689298eaa89SMikulas Patocka available_sectors = o->split_boundary - 2690298eaa89SMikulas Patocka ((unsigned)bio->bi_iter.bi_sector & (o->split_boundary - 1)); 2691298eaa89SMikulas Patocka 2692298eaa89SMikulas Patocka if (bio_sectors(bio) > available_sectors) 2693298eaa89SMikulas Patocka dm_accept_partial_bio(bio, available_sectors); 2694298eaa89SMikulas Patocka 26951da177e4SLinus Torvalds /* Only tell snapshots if this is a write */ 2696b2155578SMikulas Patocka return do_origin(o->dev, bio, true); 26971da177e4SLinus Torvalds } 26981da177e4SLinus Torvalds 26991da177e4SLinus Torvalds /* 2700542f9038SMike Snitzer * Set the target "max_io_len" field to the minimum of all the snapshots' 27011da177e4SLinus Torvalds * chunk sizes. 27021da177e4SLinus Torvalds */ 27031da177e4SLinus Torvalds static void origin_resume(struct dm_target *ti) 27041da177e4SLinus Torvalds { 2705599cdf3bSMikulas Patocka struct dm_origin *o = ti->private; 27061da177e4SLinus Torvalds 2707298eaa89SMikulas Patocka o->split_boundary = get_origin_minimum_chunksize(o->dev->bdev); 2708b735fedeSMikulas Patocka 2709b735fedeSMikulas Patocka down_write(&_origins_lock); 2710b735fedeSMikulas Patocka __insert_dm_origin(o); 2711b735fedeSMikulas Patocka up_write(&_origins_lock); 2712b735fedeSMikulas Patocka } 2713b735fedeSMikulas Patocka 2714b735fedeSMikulas Patocka static void origin_postsuspend(struct dm_target *ti) 2715b735fedeSMikulas Patocka { 2716b735fedeSMikulas Patocka struct dm_origin *o = ti->private; 2717b735fedeSMikulas Patocka 2718b735fedeSMikulas Patocka down_write(&_origins_lock); 2719b735fedeSMikulas Patocka __remove_dm_origin(o); 2720b735fedeSMikulas Patocka up_write(&_origins_lock); 27211da177e4SLinus Torvalds } 27221da177e4SLinus Torvalds 2723fd7c092eSMikulas Patocka static void origin_status(struct dm_target *ti, status_type_t type, 27241f4e0ff0SAlasdair G Kergon unsigned status_flags, char *result, unsigned maxlen) 27251da177e4SLinus Torvalds { 2726599cdf3bSMikulas Patocka struct dm_origin *o = ti->private; 27271da177e4SLinus Torvalds 27281da177e4SLinus Torvalds switch (type) { 27291da177e4SLinus Torvalds case STATUSTYPE_INFO: 27301da177e4SLinus Torvalds result[0] = '\0'; 27311da177e4SLinus Torvalds break; 27321da177e4SLinus Torvalds 27331da177e4SLinus Torvalds case STATUSTYPE_TABLE: 2734599cdf3bSMikulas Patocka snprintf(result, maxlen, "%s", o->dev->name); 27351da177e4SLinus Torvalds break; 27361da177e4SLinus Torvalds } 27371da177e4SLinus Torvalds } 27381da177e4SLinus Torvalds 27398811f46cSMike Snitzer static int origin_iterate_devices(struct dm_target *ti, 27408811f46cSMike Snitzer iterate_devices_callout_fn fn, void *data) 27418811f46cSMike Snitzer { 2742599cdf3bSMikulas Patocka struct dm_origin *o = ti->private; 27438811f46cSMike Snitzer 2744599cdf3bSMikulas Patocka return fn(ti, o->dev, 0, ti->len, data); 27458811f46cSMike Snitzer } 27468811f46cSMike Snitzer 27471da177e4SLinus Torvalds static struct target_type origin_target = { 27481da177e4SLinus Torvalds .name = "snapshot-origin", 2749b735fedeSMikulas Patocka .version = {1, 9, 0}, 27501da177e4SLinus Torvalds .module = THIS_MODULE, 27511da177e4SLinus Torvalds .ctr = origin_ctr, 27521da177e4SLinus Torvalds .dtr = origin_dtr, 27531da177e4SLinus Torvalds .map = origin_map, 27541da177e4SLinus Torvalds .resume = origin_resume, 2755b735fedeSMikulas Patocka .postsuspend = origin_postsuspend, 27561da177e4SLinus Torvalds .status = origin_status, 27578811f46cSMike Snitzer .iterate_devices = origin_iterate_devices, 27581da177e4SLinus Torvalds }; 27591da177e4SLinus Torvalds 27601da177e4SLinus Torvalds static struct target_type snapshot_target = { 27611da177e4SLinus Torvalds .name = "snapshot", 27622e602385SMike Snitzer .version = {1, 16, 0}, 27631da177e4SLinus Torvalds .module = THIS_MODULE, 27641da177e4SLinus Torvalds .ctr = snapshot_ctr, 27651da177e4SLinus Torvalds .dtr = snapshot_dtr, 27661da177e4SLinus Torvalds .map = snapshot_map, 2767cd45daffSMikulas Patocka .end_io = snapshot_end_io, 2768c1f0c183SMike Snitzer .preresume = snapshot_preresume, 27691da177e4SLinus Torvalds .resume = snapshot_resume, 27701da177e4SLinus Torvalds .status = snapshot_status, 27718811f46cSMike Snitzer .iterate_devices = snapshot_iterate_devices, 27722e602385SMike Snitzer .io_hints = snapshot_io_hints, 27731da177e4SLinus Torvalds }; 27741da177e4SLinus Torvalds 2775d698aa45SMikulas Patocka static struct target_type merge_target = { 2776d698aa45SMikulas Patocka .name = dm_snapshot_merge_target_name, 27772e602385SMike Snitzer .version = {1, 5, 0}, 2778d698aa45SMikulas Patocka .module = THIS_MODULE, 2779d698aa45SMikulas Patocka .ctr = snapshot_ctr, 2780d698aa45SMikulas Patocka .dtr = snapshot_dtr, 27813452c2a1SMikulas Patocka .map = snapshot_merge_map, 2782d698aa45SMikulas Patocka .end_io = snapshot_end_io, 27831e03f97eSMikulas Patocka .presuspend = snapshot_merge_presuspend, 2784d698aa45SMikulas Patocka .preresume = snapshot_preresume, 27851e03f97eSMikulas Patocka .resume = snapshot_merge_resume, 2786d698aa45SMikulas Patocka .status = snapshot_status, 2787d698aa45SMikulas Patocka .iterate_devices = snapshot_iterate_devices, 27882e602385SMike Snitzer .io_hints = snapshot_io_hints, 2789d698aa45SMikulas Patocka }; 2790d698aa45SMikulas Patocka 27911da177e4SLinus Torvalds static int __init dm_snapshot_init(void) 27921da177e4SLinus Torvalds { 27931da177e4SLinus Torvalds int r; 27941da177e4SLinus Torvalds 27954db6bfe0SAlasdair G Kergon r = dm_exception_store_init(); 27964db6bfe0SAlasdair G Kergon if (r) { 27974db6bfe0SAlasdair G Kergon DMERR("Failed to initialize exception stores"); 27984db6bfe0SAlasdair G Kergon return r; 27994db6bfe0SAlasdair G Kergon } 28004db6bfe0SAlasdair G Kergon 28011da177e4SLinus Torvalds r = init_origin_hash(); 28021da177e4SLinus Torvalds if (r) { 28031da177e4SLinus Torvalds DMERR("init_origin_hash failed."); 2804d698aa45SMikulas Patocka goto bad_origin_hash; 28051da177e4SLinus Torvalds } 28061da177e4SLinus Torvalds 28071d4989c8SJon Brassow exception_cache = KMEM_CACHE(dm_exception, 0); 28081da177e4SLinus Torvalds if (!exception_cache) { 28091da177e4SLinus Torvalds DMERR("Couldn't create exception cache."); 28101da177e4SLinus Torvalds r = -ENOMEM; 2811d698aa45SMikulas Patocka goto bad_exception_cache; 28121da177e4SLinus Torvalds } 28131da177e4SLinus Torvalds 2814028867acSAlasdair G Kergon pending_cache = KMEM_CACHE(dm_snap_pending_exception, 0); 28151da177e4SLinus Torvalds if (!pending_cache) { 28161da177e4SLinus Torvalds DMERR("Couldn't create pending cache."); 28171da177e4SLinus Torvalds r = -ENOMEM; 2818d698aa45SMikulas Patocka goto bad_pending_cache; 28191da177e4SLinus Torvalds } 28201da177e4SLinus Torvalds 28217e6358d2Smonty_pavel@sina.com r = dm_register_target(&snapshot_target); 28227e6358d2Smonty_pavel@sina.com if (r < 0) { 28237e6358d2Smonty_pavel@sina.com DMERR("snapshot target register failed %d", r); 28247e6358d2Smonty_pavel@sina.com goto bad_register_snapshot_target; 28257e6358d2Smonty_pavel@sina.com } 28267e6358d2Smonty_pavel@sina.com 28277e6358d2Smonty_pavel@sina.com r = dm_register_target(&origin_target); 28287e6358d2Smonty_pavel@sina.com if (r < 0) { 28297e6358d2Smonty_pavel@sina.com DMERR("Origin target register failed %d", r); 28307e6358d2Smonty_pavel@sina.com goto bad_register_origin_target; 28317e6358d2Smonty_pavel@sina.com } 28327e6358d2Smonty_pavel@sina.com 28337e6358d2Smonty_pavel@sina.com r = dm_register_target(&merge_target); 28347e6358d2Smonty_pavel@sina.com if (r < 0) { 28357e6358d2Smonty_pavel@sina.com DMERR("Merge target register failed %d", r); 28367e6358d2Smonty_pavel@sina.com goto bad_register_merge_target; 28377e6358d2Smonty_pavel@sina.com } 28387e6358d2Smonty_pavel@sina.com 28391da177e4SLinus Torvalds return 0; 28401da177e4SLinus Torvalds 2841d698aa45SMikulas Patocka bad_register_merge_target: 28421da177e4SLinus Torvalds dm_unregister_target(&origin_target); 2843d698aa45SMikulas Patocka bad_register_origin_target: 28441da177e4SLinus Torvalds dm_unregister_target(&snapshot_target); 2845034a186dSJonathan Brassow bad_register_snapshot_target: 28467e6358d2Smonty_pavel@sina.com kmem_cache_destroy(pending_cache); 28477e6358d2Smonty_pavel@sina.com bad_pending_cache: 28487e6358d2Smonty_pavel@sina.com kmem_cache_destroy(exception_cache); 28497e6358d2Smonty_pavel@sina.com bad_exception_cache: 28507e6358d2Smonty_pavel@sina.com exit_origin_hash(); 28517e6358d2Smonty_pavel@sina.com bad_origin_hash: 2852034a186dSJonathan Brassow dm_exception_store_exit(); 2853d698aa45SMikulas Patocka 28541da177e4SLinus Torvalds return r; 28551da177e4SLinus Torvalds } 28561da177e4SLinus Torvalds 28571da177e4SLinus Torvalds static void __exit dm_snapshot_exit(void) 28581da177e4SLinus Torvalds { 285910d3bd09SMikulas Patocka dm_unregister_target(&snapshot_target); 286010d3bd09SMikulas Patocka dm_unregister_target(&origin_target); 2861d698aa45SMikulas Patocka dm_unregister_target(&merge_target); 28621da177e4SLinus Torvalds 28631da177e4SLinus Torvalds exit_origin_hash(); 28641da177e4SLinus Torvalds kmem_cache_destroy(pending_cache); 28651da177e4SLinus Torvalds kmem_cache_destroy(exception_cache); 28664db6bfe0SAlasdair G Kergon 28674db6bfe0SAlasdair G Kergon dm_exception_store_exit(); 28681da177e4SLinus Torvalds } 28691da177e4SLinus Torvalds 28701da177e4SLinus Torvalds /* Module hooks */ 28711da177e4SLinus Torvalds module_init(dm_snapshot_init); 28721da177e4SLinus Torvalds module_exit(dm_snapshot_exit); 28731da177e4SLinus Torvalds 28741da177e4SLinus Torvalds MODULE_DESCRIPTION(DM_NAME " snapshot target"); 28751da177e4SLinus Torvalds MODULE_AUTHOR("Joe Thornber"); 28761da177e4SLinus Torvalds MODULE_LICENSE("GPL"); 287723cb2109SMikulas Patocka MODULE_ALIAS("dm-snapshot-origin"); 287823cb2109SMikulas Patocka MODULE_ALIAS("dm-snapshot-merge"); 2879