11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * dm-snapshot.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 2001-2002 Sistina Software (UK) Limited. 51da177e4SLinus Torvalds * 61da177e4SLinus Torvalds * This file is released under the GPL. 71da177e4SLinus Torvalds */ 81da177e4SLinus Torvalds 91da177e4SLinus Torvalds #include <linux/blkdev.h> 101da177e4SLinus Torvalds #include <linux/device-mapper.h> 1190fa1527SMikulas Patocka #include <linux/delay.h> 121da177e4SLinus Torvalds #include <linux/fs.h> 131da177e4SLinus Torvalds #include <linux/init.h> 141da177e4SLinus Torvalds #include <linux/kdev_t.h> 151da177e4SLinus Torvalds #include <linux/list.h> 161da177e4SLinus Torvalds #include <linux/mempool.h> 171da177e4SLinus Torvalds #include <linux/module.h> 181da177e4SLinus Torvalds #include <linux/slab.h> 191da177e4SLinus Torvalds #include <linux/vmalloc.h> 206f3c3f0aSvignesh babu #include <linux/log2.h> 21a765e20eSAlasdair G Kergon #include <linux/dm-kcopyd.h> 22721b1d98SNikos Tsironis #include <linux/semaphore.h> 231da177e4SLinus Torvalds 24b735fedeSMikulas Patocka #include "dm.h" 25b735fedeSMikulas Patocka 26aea53d92SJonathan Brassow #include "dm-exception-store.h" 271da177e4SLinus Torvalds 2872d94861SAlasdair G Kergon #define DM_MSG_PREFIX "snapshots" 2972d94861SAlasdair G Kergon 30d698aa45SMikulas Patocka static const char dm_snapshot_merge_target_name[] = "snapshot-merge"; 31d698aa45SMikulas Patocka 32d698aa45SMikulas Patocka #define dm_target_is_snapshot_merge(ti) \ 33d698aa45SMikulas Patocka ((ti)->type->name == dm_snapshot_merge_target_name) 34d698aa45SMikulas Patocka 351da177e4SLinus Torvalds /* 36cd45daffSMikulas Patocka * The size of the mempool used to track chunks in use. 37cd45daffSMikulas Patocka */ 38cd45daffSMikulas Patocka #define MIN_IOS 256 39cd45daffSMikulas Patocka 40ccc45ea8SJonathan Brassow #define DM_TRACKED_CHUNK_HASH_SIZE 16 41ccc45ea8SJonathan Brassow #define DM_TRACKED_CHUNK_HASH(x) ((unsigned long)(x) & \ 42ccc45ea8SJonathan Brassow (DM_TRACKED_CHUNK_HASH_SIZE - 1)) 43ccc45ea8SJonathan Brassow 44191437a5SJon Brassow struct dm_exception_table { 45ccc45ea8SJonathan Brassow uint32_t hash_mask; 46ccc45ea8SJonathan Brassow unsigned hash_shift; 47ccc45ea8SJonathan Brassow struct list_head *table; 48ccc45ea8SJonathan Brassow }; 49ccc45ea8SJonathan Brassow 50ccc45ea8SJonathan Brassow struct dm_snapshot { 51ae1093beSMikulas Patocka struct mutex lock; 52ccc45ea8SJonathan Brassow 53ccc45ea8SJonathan Brassow struct dm_dev *origin; 54fc56f6fbSMike Snitzer struct dm_dev *cow; 55fc56f6fbSMike Snitzer 56fc56f6fbSMike Snitzer struct dm_target *ti; 57ccc45ea8SJonathan Brassow 58ccc45ea8SJonathan Brassow /* List of snapshots per Origin */ 59ccc45ea8SJonathan Brassow struct list_head list; 60ccc45ea8SJonathan Brassow 61d8ddb1cfSMike Snitzer /* 62d8ddb1cfSMike Snitzer * You can't use a snapshot if this is 0 (e.g. if full). 63d8ddb1cfSMike Snitzer * A snapshot-merge target never clears this. 64d8ddb1cfSMike Snitzer */ 65ccc45ea8SJonathan Brassow int valid; 66ccc45ea8SJonathan Brassow 6776c44f6dSMikulas Patocka /* 6876c44f6dSMikulas Patocka * The snapshot overflowed because of a write to the snapshot device. 6976c44f6dSMikulas Patocka * We don't have to invalidate the snapshot in this case, but we need 7076c44f6dSMikulas Patocka * to prevent further writes. 7176c44f6dSMikulas Patocka */ 7276c44f6dSMikulas Patocka int snapshot_overflowed; 7376c44f6dSMikulas Patocka 74ccc45ea8SJonathan Brassow /* Origin writes don't trigger exceptions until this is set */ 75ccc45ea8SJonathan Brassow int active; 76ccc45ea8SJonathan Brassow 77ccc45ea8SJonathan Brassow atomic_t pending_exceptions_count; 78ccc45ea8SJonathan Brassow 79230c83afSMikulas Patocka /* Protected by "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 109721b1d98SNikos Tsironis /* Maximum number of in-flight COW jobs. */ 110721b1d98SNikos Tsironis struct semaphore cow_count; 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 */ 134d8ddb1cfSMike Snitzer int merge_failed; 135d8ddb1cfSMike Snitzer 1369fe86254SMikulas Patocka /* 1379fe86254SMikulas Patocka * Incoming bios that overlap with chunks being merged must wait 1389fe86254SMikulas Patocka * for them to be committed. 1399fe86254SMikulas Patocka */ 1409fe86254SMikulas Patocka struct bio_list bios_queued_during_merge; 141ccc45ea8SJonathan Brassow }; 142ccc45ea8SJonathan Brassow 1431e03f97eSMikulas Patocka /* 1441e03f97eSMikulas Patocka * state_bits: 1451e03f97eSMikulas Patocka * RUNNING_MERGE - Merge operation is in progress. 1461e03f97eSMikulas Patocka * SHUTDOWN_MERGE - Set to signal that merge needs to be stopped; 1471e03f97eSMikulas Patocka * cleared afterwards. 1481e03f97eSMikulas Patocka */ 1491e03f97eSMikulas Patocka #define RUNNING_MERGE 0 1501e03f97eSMikulas Patocka #define SHUTDOWN_MERGE 1 1511e03f97eSMikulas Patocka 152721b1d98SNikos Tsironis /* 153721b1d98SNikos Tsironis * Maximum number of chunks being copied on write. 154721b1d98SNikos Tsironis * 155721b1d98SNikos Tsironis * The value was decided experimentally as a trade-off between memory 156721b1d98SNikos Tsironis * consumption, stalling the kernel's workqueues and maintaining a high enough 157721b1d98SNikos Tsironis * throughput. 158721b1d98SNikos Tsironis */ 159721b1d98SNikos Tsironis #define DEFAULT_COW_THRESHOLD 2048 160721b1d98SNikos Tsironis 161721b1d98SNikos Tsironis static int cow_threshold = DEFAULT_COW_THRESHOLD; 162721b1d98SNikos Tsironis module_param_named(snapshot_cow_threshold, cow_threshold, int, 0644); 163721b1d98SNikos Tsironis MODULE_PARM_DESC(snapshot_cow_threshold, "Maximum number of chunks being copied on write"); 164721b1d98SNikos Tsironis 165df5d2e90SMikulas Patocka DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(snapshot_copy_throttle, 166df5d2e90SMikulas Patocka "A percentage of time allocated for copy on write"); 167df5d2e90SMikulas Patocka 168c2411045SMikulas Patocka struct dm_dev *dm_snap_origin(struct dm_snapshot *s) 169c2411045SMikulas Patocka { 170c2411045SMikulas Patocka return s->origin; 171c2411045SMikulas Patocka } 172c2411045SMikulas Patocka EXPORT_SYMBOL(dm_snap_origin); 173c2411045SMikulas Patocka 174fc56f6fbSMike Snitzer struct dm_dev *dm_snap_cow(struct dm_snapshot *s) 175fc56f6fbSMike Snitzer { 176fc56f6fbSMike Snitzer return s->cow; 177fc56f6fbSMike Snitzer } 178fc56f6fbSMike Snitzer EXPORT_SYMBOL(dm_snap_cow); 179fc56f6fbSMike Snitzer 180ccc45ea8SJonathan Brassow static sector_t chunk_to_sector(struct dm_exception_store *store, 181ccc45ea8SJonathan Brassow chunk_t chunk) 182ccc45ea8SJonathan Brassow { 183ccc45ea8SJonathan Brassow return chunk << store->chunk_shift; 184ccc45ea8SJonathan Brassow } 185ccc45ea8SJonathan Brassow 186ccc45ea8SJonathan Brassow static int bdev_equal(struct block_device *lhs, struct block_device *rhs) 187ccc45ea8SJonathan Brassow { 188ccc45ea8SJonathan Brassow /* 189ccc45ea8SJonathan Brassow * There is only ever one instance of a particular block 190ccc45ea8SJonathan Brassow * device so we can compare pointers safely. 191ccc45ea8SJonathan Brassow */ 192ccc45ea8SJonathan Brassow return lhs == rhs; 193ccc45ea8SJonathan Brassow } 194ccc45ea8SJonathan Brassow 195028867acSAlasdair G Kergon struct dm_snap_pending_exception { 1961d4989c8SJon Brassow struct dm_exception e; 1971da177e4SLinus Torvalds 1981da177e4SLinus Torvalds /* 1991da177e4SLinus Torvalds * Origin buffers waiting for this to complete are held 2001da177e4SLinus Torvalds * in a bio list 2011da177e4SLinus Torvalds */ 2021da177e4SLinus Torvalds struct bio_list origin_bios; 2031da177e4SLinus Torvalds struct bio_list snapshot_bios; 2041da177e4SLinus Torvalds 2051da177e4SLinus Torvalds /* Pointer back to snapshot context */ 2061da177e4SLinus Torvalds struct dm_snapshot *snap; 2071da177e4SLinus Torvalds 2081da177e4SLinus Torvalds /* 2091da177e4SLinus Torvalds * 1 indicates the exception has already been sent to 2101da177e4SLinus Torvalds * kcopyd. 2111da177e4SLinus Torvalds */ 2121da177e4SLinus Torvalds int started; 213a6e50b40SMikulas Patocka 214230c83afSMikulas Patocka /* There was copying error. */ 215230c83afSMikulas Patocka int copy_error; 216230c83afSMikulas Patocka 217230c83afSMikulas Patocka /* A sequence number, it is used for in-order completion. */ 218230c83afSMikulas Patocka sector_t exception_sequence; 219230c83afSMikulas Patocka 2203db2776dSDavid Jeffery struct rb_node out_of_order_node; 221230c83afSMikulas Patocka 222a6e50b40SMikulas Patocka /* 223a6e50b40SMikulas Patocka * For writing a complete chunk, bypassing the copy. 224a6e50b40SMikulas Patocka */ 225a6e50b40SMikulas Patocka struct bio *full_bio; 226a6e50b40SMikulas Patocka bio_end_io_t *full_bio_end_io; 2271da177e4SLinus Torvalds }; 2281da177e4SLinus Torvalds 2291da177e4SLinus Torvalds /* 2301da177e4SLinus Torvalds * Hash table mapping origin volumes to lists of snapshots and 2311da177e4SLinus Torvalds * a lock to protect it 2321da177e4SLinus Torvalds */ 233e18b890bSChristoph Lameter static struct kmem_cache *exception_cache; 234e18b890bSChristoph Lameter static struct kmem_cache *pending_cache; 2351da177e4SLinus Torvalds 236cd45daffSMikulas Patocka struct dm_snap_tracked_chunk { 237cd45daffSMikulas Patocka struct hlist_node node; 238cd45daffSMikulas Patocka chunk_t chunk; 239cd45daffSMikulas Patocka }; 240cd45daffSMikulas Patocka 241ee18026aSMikulas Patocka static void init_tracked_chunk(struct bio *bio) 242ee18026aSMikulas Patocka { 243ee18026aSMikulas Patocka struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk)); 244ee18026aSMikulas Patocka INIT_HLIST_NODE(&c->node); 245ee18026aSMikulas Patocka } 246ee18026aSMikulas Patocka 247ee18026aSMikulas Patocka static bool is_bio_tracked(struct bio *bio) 248ee18026aSMikulas Patocka { 249ee18026aSMikulas Patocka struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk)); 250ee18026aSMikulas Patocka return !hlist_unhashed(&c->node); 251ee18026aSMikulas Patocka } 252ee18026aSMikulas Patocka 253ee18026aSMikulas Patocka static void track_chunk(struct dm_snapshot *s, struct bio *bio, chunk_t chunk) 254cd45daffSMikulas Patocka { 25542bc954fSMikulas Patocka struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk)); 256cd45daffSMikulas Patocka 257cd45daffSMikulas Patocka c->chunk = chunk; 258cd45daffSMikulas Patocka 2599aa0c0e6SMikulas Patocka spin_lock_irq(&s->tracked_chunk_lock); 260cd45daffSMikulas Patocka hlist_add_head(&c->node, 261cd45daffSMikulas Patocka &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)]); 2629aa0c0e6SMikulas Patocka spin_unlock_irq(&s->tracked_chunk_lock); 263cd45daffSMikulas Patocka } 264cd45daffSMikulas Patocka 265ee18026aSMikulas Patocka static void stop_tracking_chunk(struct dm_snapshot *s, struct bio *bio) 266cd45daffSMikulas Patocka { 267ee18026aSMikulas Patocka struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk)); 268cd45daffSMikulas Patocka unsigned long flags; 269cd45daffSMikulas Patocka 270cd45daffSMikulas Patocka spin_lock_irqsave(&s->tracked_chunk_lock, flags); 271cd45daffSMikulas Patocka hlist_del(&c->node); 272cd45daffSMikulas Patocka spin_unlock_irqrestore(&s->tracked_chunk_lock, flags); 273cd45daffSMikulas Patocka } 274cd45daffSMikulas Patocka 275a8d41b59SMikulas Patocka static int __chunk_is_tracked(struct dm_snapshot *s, chunk_t chunk) 276a8d41b59SMikulas Patocka { 277a8d41b59SMikulas Patocka struct dm_snap_tracked_chunk *c; 278a8d41b59SMikulas Patocka int found = 0; 279a8d41b59SMikulas Patocka 280a8d41b59SMikulas Patocka spin_lock_irq(&s->tracked_chunk_lock); 281a8d41b59SMikulas Patocka 282b67bfe0dSSasha Levin hlist_for_each_entry(c, 283a8d41b59SMikulas Patocka &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)], node) { 284a8d41b59SMikulas Patocka if (c->chunk == chunk) { 285a8d41b59SMikulas Patocka found = 1; 286a8d41b59SMikulas Patocka break; 287a8d41b59SMikulas Patocka } 288a8d41b59SMikulas Patocka } 289a8d41b59SMikulas Patocka 290a8d41b59SMikulas Patocka spin_unlock_irq(&s->tracked_chunk_lock); 291a8d41b59SMikulas Patocka 292a8d41b59SMikulas Patocka return found; 293a8d41b59SMikulas Patocka } 294a8d41b59SMikulas Patocka 2951da177e4SLinus Torvalds /* 296615d1eb9SMike Snitzer * This conflicting I/O is extremely improbable in the caller, 297615d1eb9SMike Snitzer * so msleep(1) is sufficient and there is no need for a wait queue. 298615d1eb9SMike Snitzer */ 299615d1eb9SMike Snitzer static void __check_for_conflicting_io(struct dm_snapshot *s, chunk_t chunk) 300615d1eb9SMike Snitzer { 301615d1eb9SMike Snitzer while (__chunk_is_tracked(s, chunk)) 302615d1eb9SMike Snitzer msleep(1); 303615d1eb9SMike Snitzer } 304615d1eb9SMike Snitzer 305615d1eb9SMike Snitzer /* 3061da177e4SLinus Torvalds * One of these per registered origin, held in the snapshot_origins hash 3071da177e4SLinus Torvalds */ 3081da177e4SLinus Torvalds struct origin { 3091da177e4SLinus Torvalds /* The origin device */ 3101da177e4SLinus Torvalds struct block_device *bdev; 3111da177e4SLinus Torvalds 3121da177e4SLinus Torvalds struct list_head hash_list; 3131da177e4SLinus Torvalds 3141da177e4SLinus Torvalds /* List of snapshots for this origin */ 3151da177e4SLinus Torvalds struct list_head snapshots; 3161da177e4SLinus Torvalds }; 3171da177e4SLinus Torvalds 3181da177e4SLinus Torvalds /* 319b735fedeSMikulas Patocka * This structure is allocated for each origin target 320b735fedeSMikulas Patocka */ 321b735fedeSMikulas Patocka struct dm_origin { 322b735fedeSMikulas Patocka struct dm_dev *dev; 323b735fedeSMikulas Patocka struct dm_target *ti; 324b735fedeSMikulas Patocka unsigned split_boundary; 325b735fedeSMikulas Patocka struct list_head hash_list; 326b735fedeSMikulas Patocka }; 327b735fedeSMikulas Patocka 328b735fedeSMikulas Patocka /* 3291da177e4SLinus Torvalds * Size of the hash table for origin volumes. If we make this 3301da177e4SLinus Torvalds * the size of the minors list then it should be nearly perfect 3311da177e4SLinus Torvalds */ 3321da177e4SLinus Torvalds #define ORIGIN_HASH_SIZE 256 3331da177e4SLinus Torvalds #define ORIGIN_MASK 0xFF 3341da177e4SLinus Torvalds static struct list_head *_origins; 335b735fedeSMikulas Patocka static struct list_head *_dm_origins; 3361da177e4SLinus Torvalds static struct rw_semaphore _origins_lock; 3371da177e4SLinus Torvalds 33873dfd078SMikulas Patocka static DECLARE_WAIT_QUEUE_HEAD(_pending_exceptions_done); 33973dfd078SMikulas Patocka static DEFINE_SPINLOCK(_pending_exceptions_done_spinlock); 34073dfd078SMikulas Patocka static uint64_t _pending_exceptions_done_count; 34173dfd078SMikulas Patocka 3421da177e4SLinus Torvalds static int init_origin_hash(void) 3431da177e4SLinus Torvalds { 3441da177e4SLinus Torvalds int i; 3451da177e4SLinus Torvalds 3466da2ec56SKees Cook _origins = kmalloc_array(ORIGIN_HASH_SIZE, sizeof(struct list_head), 3471da177e4SLinus Torvalds GFP_KERNEL); 3481da177e4SLinus Torvalds if (!_origins) { 349b735fedeSMikulas Patocka DMERR("unable to allocate memory for _origins"); 3501da177e4SLinus Torvalds return -ENOMEM; 3511da177e4SLinus Torvalds } 3521da177e4SLinus Torvalds for (i = 0; i < ORIGIN_HASH_SIZE; i++) 3531da177e4SLinus Torvalds INIT_LIST_HEAD(_origins + i); 354b735fedeSMikulas Patocka 3556da2ec56SKees Cook _dm_origins = kmalloc_array(ORIGIN_HASH_SIZE, 3566da2ec56SKees Cook sizeof(struct list_head), 357b735fedeSMikulas Patocka GFP_KERNEL); 358b735fedeSMikulas Patocka if (!_dm_origins) { 359b735fedeSMikulas Patocka DMERR("unable to allocate memory for _dm_origins"); 360b735fedeSMikulas Patocka kfree(_origins); 361b735fedeSMikulas Patocka return -ENOMEM; 362b735fedeSMikulas Patocka } 363b735fedeSMikulas Patocka for (i = 0; i < ORIGIN_HASH_SIZE; i++) 364b735fedeSMikulas Patocka INIT_LIST_HEAD(_dm_origins + i); 365b735fedeSMikulas Patocka 3661da177e4SLinus Torvalds init_rwsem(&_origins_lock); 3671da177e4SLinus Torvalds 3681da177e4SLinus Torvalds return 0; 3691da177e4SLinus Torvalds } 3701da177e4SLinus Torvalds 3711da177e4SLinus Torvalds static void exit_origin_hash(void) 3721da177e4SLinus Torvalds { 3731da177e4SLinus Torvalds kfree(_origins); 374b735fedeSMikulas Patocka kfree(_dm_origins); 3751da177e4SLinus Torvalds } 3761da177e4SLinus Torvalds 377028867acSAlasdair G Kergon static unsigned origin_hash(struct block_device *bdev) 3781da177e4SLinus Torvalds { 3791da177e4SLinus Torvalds return bdev->bd_dev & ORIGIN_MASK; 3801da177e4SLinus Torvalds } 3811da177e4SLinus Torvalds 3821da177e4SLinus Torvalds static struct origin *__lookup_origin(struct block_device *origin) 3831da177e4SLinus Torvalds { 3841da177e4SLinus Torvalds struct list_head *ol; 3851da177e4SLinus Torvalds struct origin *o; 3861da177e4SLinus Torvalds 3871da177e4SLinus Torvalds ol = &_origins[origin_hash(origin)]; 3881da177e4SLinus Torvalds list_for_each_entry (o, ol, hash_list) 3891da177e4SLinus Torvalds if (bdev_equal(o->bdev, origin)) 3901da177e4SLinus Torvalds return o; 3911da177e4SLinus Torvalds 3921da177e4SLinus Torvalds return NULL; 3931da177e4SLinus Torvalds } 3941da177e4SLinus Torvalds 3951da177e4SLinus Torvalds static void __insert_origin(struct origin *o) 3961da177e4SLinus Torvalds { 3971da177e4SLinus Torvalds struct list_head *sl = &_origins[origin_hash(o->bdev)]; 3981da177e4SLinus Torvalds list_add_tail(&o->hash_list, sl); 3991da177e4SLinus Torvalds } 4001da177e4SLinus Torvalds 401b735fedeSMikulas Patocka static struct dm_origin *__lookup_dm_origin(struct block_device *origin) 402b735fedeSMikulas Patocka { 403b735fedeSMikulas Patocka struct list_head *ol; 404b735fedeSMikulas Patocka struct dm_origin *o; 405b735fedeSMikulas Patocka 406b735fedeSMikulas Patocka ol = &_dm_origins[origin_hash(origin)]; 407b735fedeSMikulas Patocka list_for_each_entry (o, ol, hash_list) 408b735fedeSMikulas Patocka if (bdev_equal(o->dev->bdev, origin)) 409b735fedeSMikulas Patocka return o; 410b735fedeSMikulas Patocka 411b735fedeSMikulas Patocka return NULL; 412b735fedeSMikulas Patocka } 413b735fedeSMikulas Patocka 414b735fedeSMikulas Patocka static void __insert_dm_origin(struct dm_origin *o) 415b735fedeSMikulas Patocka { 416b735fedeSMikulas Patocka struct list_head *sl = &_dm_origins[origin_hash(o->dev->bdev)]; 417b735fedeSMikulas Patocka list_add_tail(&o->hash_list, sl); 418b735fedeSMikulas Patocka } 419b735fedeSMikulas Patocka 420b735fedeSMikulas Patocka static void __remove_dm_origin(struct dm_origin *o) 421b735fedeSMikulas Patocka { 422b735fedeSMikulas Patocka list_del(&o->hash_list); 423b735fedeSMikulas Patocka } 424b735fedeSMikulas Patocka 4251da177e4SLinus Torvalds /* 426c1f0c183SMike Snitzer * _origins_lock must be held when calling this function. 427c1f0c183SMike Snitzer * Returns number of snapshots registered using the supplied cow device, plus: 428c1f0c183SMike Snitzer * snap_src - a snapshot suitable for use as a source of exception handover 429c1f0c183SMike Snitzer * snap_dest - a snapshot capable of receiving exception handover. 4309d3b15c4SMikulas Patocka * snap_merge - an existing snapshot-merge target linked to the same origin. 4319d3b15c4SMikulas Patocka * There can be at most one snapshot-merge target. The parameter is optional. 432c1f0c183SMike Snitzer * 4339d3b15c4SMikulas Patocka * Possible return values and states of snap_src and snap_dest. 434c1f0c183SMike Snitzer * 0: NULL, NULL - first new snapshot 435c1f0c183SMike Snitzer * 1: snap_src, NULL - normal snapshot 436c1f0c183SMike Snitzer * 2: snap_src, snap_dest - waiting for handover 437c1f0c183SMike Snitzer * 2: snap_src, NULL - handed over, waiting for old to be deleted 438c1f0c183SMike Snitzer * 1: NULL, snap_dest - source got destroyed without handover 439c1f0c183SMike Snitzer */ 440c1f0c183SMike Snitzer static int __find_snapshots_sharing_cow(struct dm_snapshot *snap, 441c1f0c183SMike Snitzer struct dm_snapshot **snap_src, 4429d3b15c4SMikulas Patocka struct dm_snapshot **snap_dest, 4439d3b15c4SMikulas Patocka struct dm_snapshot **snap_merge) 444c1f0c183SMike Snitzer { 445c1f0c183SMike Snitzer struct dm_snapshot *s; 446c1f0c183SMike Snitzer struct origin *o; 447c1f0c183SMike Snitzer int count = 0; 448c1f0c183SMike Snitzer int active; 449c1f0c183SMike Snitzer 450c1f0c183SMike Snitzer o = __lookup_origin(snap->origin->bdev); 451c1f0c183SMike Snitzer if (!o) 452c1f0c183SMike Snitzer goto out; 453c1f0c183SMike Snitzer 454c1f0c183SMike Snitzer list_for_each_entry(s, &o->snapshots, list) { 4559d3b15c4SMikulas Patocka if (dm_target_is_snapshot_merge(s->ti) && snap_merge) 4569d3b15c4SMikulas Patocka *snap_merge = s; 457c1f0c183SMike Snitzer if (!bdev_equal(s->cow->bdev, snap->cow->bdev)) 458c1f0c183SMike Snitzer continue; 459c1f0c183SMike Snitzer 460ae1093beSMikulas Patocka mutex_lock(&s->lock); 461c1f0c183SMike Snitzer active = s->active; 462ae1093beSMikulas Patocka mutex_unlock(&s->lock); 463c1f0c183SMike Snitzer 464c1f0c183SMike Snitzer if (active) { 465c1f0c183SMike Snitzer if (snap_src) 466c1f0c183SMike Snitzer *snap_src = s; 467c1f0c183SMike Snitzer } else if (snap_dest) 468c1f0c183SMike Snitzer *snap_dest = s; 469c1f0c183SMike Snitzer 470c1f0c183SMike Snitzer count++; 471c1f0c183SMike Snitzer } 472c1f0c183SMike Snitzer 473c1f0c183SMike Snitzer out: 474c1f0c183SMike Snitzer return count; 475c1f0c183SMike Snitzer } 476c1f0c183SMike Snitzer 477c1f0c183SMike Snitzer /* 478c1f0c183SMike Snitzer * On success, returns 1 if this snapshot is a handover destination, 479c1f0c183SMike Snitzer * otherwise returns 0. 480c1f0c183SMike Snitzer */ 481c1f0c183SMike Snitzer static int __validate_exception_handover(struct dm_snapshot *snap) 482c1f0c183SMike Snitzer { 483c1f0c183SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 4849d3b15c4SMikulas Patocka struct dm_snapshot *snap_merge = NULL; 485c1f0c183SMike Snitzer 486c1f0c183SMike Snitzer /* Does snapshot need exceptions handed over to it? */ 4879d3b15c4SMikulas Patocka if ((__find_snapshots_sharing_cow(snap, &snap_src, &snap_dest, 4889d3b15c4SMikulas Patocka &snap_merge) == 2) || 489c1f0c183SMike Snitzer snap_dest) { 490c1f0c183SMike Snitzer snap->ti->error = "Snapshot cow pairing for exception " 491c1f0c183SMike Snitzer "table handover failed"; 492c1f0c183SMike Snitzer return -EINVAL; 493c1f0c183SMike Snitzer } 494c1f0c183SMike Snitzer 495c1f0c183SMike Snitzer /* 496c1f0c183SMike Snitzer * If no snap_src was found, snap cannot become a handover 497c1f0c183SMike Snitzer * destination. 498c1f0c183SMike Snitzer */ 499c1f0c183SMike Snitzer if (!snap_src) 500c1f0c183SMike Snitzer return 0; 501c1f0c183SMike Snitzer 5029d3b15c4SMikulas Patocka /* 5039d3b15c4SMikulas Patocka * Non-snapshot-merge handover? 5049d3b15c4SMikulas Patocka */ 5059d3b15c4SMikulas Patocka if (!dm_target_is_snapshot_merge(snap->ti)) 5069d3b15c4SMikulas Patocka return 1; 5079d3b15c4SMikulas Patocka 5089d3b15c4SMikulas Patocka /* 5099d3b15c4SMikulas Patocka * Do not allow more than one merging snapshot. 5109d3b15c4SMikulas Patocka */ 5119d3b15c4SMikulas Patocka if (snap_merge) { 5129d3b15c4SMikulas Patocka snap->ti->error = "A snapshot is already merging."; 5139d3b15c4SMikulas Patocka return -EINVAL; 5149d3b15c4SMikulas Patocka } 5159d3b15c4SMikulas Patocka 5161e03f97eSMikulas Patocka if (!snap_src->store->type->prepare_merge || 5171e03f97eSMikulas Patocka !snap_src->store->type->commit_merge) { 5181e03f97eSMikulas Patocka snap->ti->error = "Snapshot exception store does not " 5191e03f97eSMikulas Patocka "support snapshot-merge."; 5201e03f97eSMikulas Patocka return -EINVAL; 5211e03f97eSMikulas Patocka } 5221e03f97eSMikulas Patocka 523c1f0c183SMike Snitzer return 1; 524c1f0c183SMike Snitzer } 525c1f0c183SMike Snitzer 526c1f0c183SMike Snitzer static void __insert_snapshot(struct origin *o, struct dm_snapshot *s) 527c1f0c183SMike Snitzer { 528c1f0c183SMike Snitzer struct dm_snapshot *l; 529c1f0c183SMike Snitzer 530c1f0c183SMike Snitzer /* Sort the list according to chunk size, largest-first smallest-last */ 531c1f0c183SMike Snitzer list_for_each_entry(l, &o->snapshots, list) 532c1f0c183SMike Snitzer if (l->store->chunk_size < s->store->chunk_size) 533c1f0c183SMike Snitzer break; 534c1f0c183SMike Snitzer list_add_tail(&s->list, &l->list); 535c1f0c183SMike Snitzer } 536c1f0c183SMike Snitzer 537c1f0c183SMike Snitzer /* 5381da177e4SLinus Torvalds * Make a note of the snapshot and its origin so we can look it 5391da177e4SLinus Torvalds * up when the origin has a write on it. 540c1f0c183SMike Snitzer * 541c1f0c183SMike Snitzer * Also validate snapshot exception store handovers. 542c1f0c183SMike Snitzer * On success, returns 1 if this registration is a handover destination, 543c1f0c183SMike Snitzer * otherwise returns 0. 5441da177e4SLinus Torvalds */ 5451da177e4SLinus Torvalds static int register_snapshot(struct dm_snapshot *snap) 5461da177e4SLinus Torvalds { 547c1f0c183SMike Snitzer struct origin *o, *new_o = NULL; 5481da177e4SLinus Torvalds struct block_device *bdev = snap->origin->bdev; 549c1f0c183SMike Snitzer int r = 0; 5501da177e4SLinus Torvalds 55160c856c8SMikulas Patocka new_o = kmalloc(sizeof(*new_o), GFP_KERNEL); 55260c856c8SMikulas Patocka if (!new_o) 55360c856c8SMikulas Patocka return -ENOMEM; 55460c856c8SMikulas Patocka 5551da177e4SLinus Torvalds down_write(&_origins_lock); 5561da177e4SLinus Torvalds 557c1f0c183SMike Snitzer r = __validate_exception_handover(snap); 558c1f0c183SMike Snitzer if (r < 0) { 559c1f0c183SMike Snitzer kfree(new_o); 560c1f0c183SMike Snitzer goto out; 561c1f0c183SMike Snitzer } 562c1f0c183SMike Snitzer 563c1f0c183SMike Snitzer o = __lookup_origin(bdev); 56460c856c8SMikulas Patocka if (o) 56560c856c8SMikulas Patocka kfree(new_o); 56660c856c8SMikulas Patocka else { 5671da177e4SLinus Torvalds /* New origin */ 56860c856c8SMikulas Patocka o = new_o; 5691da177e4SLinus Torvalds 5701da177e4SLinus Torvalds /* Initialise the struct */ 5711da177e4SLinus Torvalds INIT_LIST_HEAD(&o->snapshots); 5721da177e4SLinus Torvalds o->bdev = bdev; 5731da177e4SLinus Torvalds 5741da177e4SLinus Torvalds __insert_origin(o); 5751da177e4SLinus Torvalds } 5761da177e4SLinus Torvalds 577c1f0c183SMike Snitzer __insert_snapshot(o, snap); 578c1f0c183SMike Snitzer 579c1f0c183SMike Snitzer out: 580c1f0c183SMike Snitzer up_write(&_origins_lock); 581c1f0c183SMike Snitzer 582c1f0c183SMike Snitzer return r; 583c1f0c183SMike Snitzer } 584c1f0c183SMike Snitzer 585c1f0c183SMike Snitzer /* 586c1f0c183SMike Snitzer * Move snapshot to correct place in list according to chunk size. 587c1f0c183SMike Snitzer */ 588c1f0c183SMike Snitzer static void reregister_snapshot(struct dm_snapshot *s) 589c1f0c183SMike Snitzer { 590c1f0c183SMike Snitzer struct block_device *bdev = s->origin->bdev; 591c1f0c183SMike Snitzer 592c1f0c183SMike Snitzer down_write(&_origins_lock); 593c1f0c183SMike Snitzer 594c1f0c183SMike Snitzer list_del(&s->list); 595c1f0c183SMike Snitzer __insert_snapshot(__lookup_origin(bdev), s); 5961da177e4SLinus Torvalds 5971da177e4SLinus Torvalds up_write(&_origins_lock); 5981da177e4SLinus Torvalds } 5991da177e4SLinus Torvalds 6001da177e4SLinus Torvalds static void unregister_snapshot(struct dm_snapshot *s) 6011da177e4SLinus Torvalds { 6021da177e4SLinus Torvalds struct origin *o; 6031da177e4SLinus Torvalds 6041da177e4SLinus Torvalds down_write(&_origins_lock); 6051da177e4SLinus Torvalds o = __lookup_origin(s->origin->bdev); 6061da177e4SLinus Torvalds 6071da177e4SLinus Torvalds list_del(&s->list); 608c1f0c183SMike Snitzer if (o && list_empty(&o->snapshots)) { 6091da177e4SLinus Torvalds list_del(&o->hash_list); 6101da177e4SLinus Torvalds kfree(o); 6111da177e4SLinus Torvalds } 6121da177e4SLinus Torvalds 6131da177e4SLinus Torvalds up_write(&_origins_lock); 6141da177e4SLinus Torvalds } 6151da177e4SLinus Torvalds 6161da177e4SLinus Torvalds /* 6171da177e4SLinus Torvalds * Implementation of the exception hash tables. 618d74f81f8SMilan Broz * The lowest hash_shift bits of the chunk number are ignored, allowing 619d74f81f8SMilan Broz * some consecutive chunks to be grouped together. 6201da177e4SLinus Torvalds */ 6213510cb94SJon Brassow static int dm_exception_table_init(struct dm_exception_table *et, 6223510cb94SJon Brassow uint32_t size, unsigned hash_shift) 6231da177e4SLinus Torvalds { 6241da177e4SLinus Torvalds unsigned int i; 6251da177e4SLinus Torvalds 626d74f81f8SMilan Broz et->hash_shift = hash_shift; 6271da177e4SLinus Torvalds et->hash_mask = size - 1; 6281da177e4SLinus Torvalds et->table = dm_vcalloc(size, sizeof(struct list_head)); 6291da177e4SLinus Torvalds if (!et->table) 6301da177e4SLinus Torvalds return -ENOMEM; 6311da177e4SLinus Torvalds 6321da177e4SLinus Torvalds for (i = 0; i < size; i++) 6331da177e4SLinus Torvalds INIT_LIST_HEAD(et->table + i); 6341da177e4SLinus Torvalds 6351da177e4SLinus Torvalds return 0; 6361da177e4SLinus Torvalds } 6371da177e4SLinus Torvalds 6383510cb94SJon Brassow static void dm_exception_table_exit(struct dm_exception_table *et, 639191437a5SJon Brassow struct kmem_cache *mem) 6401da177e4SLinus Torvalds { 6411da177e4SLinus Torvalds struct list_head *slot; 6421d4989c8SJon Brassow struct dm_exception *ex, *next; 6431da177e4SLinus Torvalds int i, size; 6441da177e4SLinus Torvalds 6451da177e4SLinus Torvalds size = et->hash_mask + 1; 6461da177e4SLinus Torvalds for (i = 0; i < size; i++) { 6471da177e4SLinus Torvalds slot = et->table + i; 6481da177e4SLinus Torvalds 6491da177e4SLinus Torvalds list_for_each_entry_safe (ex, next, slot, hash_list) 6501da177e4SLinus Torvalds kmem_cache_free(mem, ex); 6511da177e4SLinus Torvalds } 6521da177e4SLinus Torvalds 6531da177e4SLinus Torvalds vfree(et->table); 6541da177e4SLinus Torvalds } 6551da177e4SLinus Torvalds 656191437a5SJon Brassow static uint32_t exception_hash(struct dm_exception_table *et, chunk_t chunk) 6571da177e4SLinus Torvalds { 658d74f81f8SMilan Broz return (chunk >> et->hash_shift) & et->hash_mask; 6591da177e4SLinus Torvalds } 6601da177e4SLinus Torvalds 6613510cb94SJon Brassow static void dm_remove_exception(struct dm_exception *e) 6621da177e4SLinus Torvalds { 6631da177e4SLinus Torvalds list_del(&e->hash_list); 6641da177e4SLinus Torvalds } 6651da177e4SLinus Torvalds 6661da177e4SLinus Torvalds /* 6671da177e4SLinus Torvalds * Return the exception data for a sector, or NULL if not 6681da177e4SLinus Torvalds * remapped. 6691da177e4SLinus Torvalds */ 6703510cb94SJon Brassow static struct dm_exception *dm_lookup_exception(struct dm_exception_table *et, 6711da177e4SLinus Torvalds chunk_t chunk) 6721da177e4SLinus Torvalds { 6731da177e4SLinus Torvalds struct list_head *slot; 6741d4989c8SJon Brassow struct dm_exception *e; 6751da177e4SLinus Torvalds 6761da177e4SLinus Torvalds slot = &et->table[exception_hash(et, chunk)]; 6771da177e4SLinus Torvalds list_for_each_entry (e, slot, hash_list) 678d74f81f8SMilan Broz if (chunk >= e->old_chunk && 679d74f81f8SMilan Broz chunk <= e->old_chunk + dm_consecutive_chunk_count(e)) 6801da177e4SLinus Torvalds return e; 6811da177e4SLinus Torvalds 6821da177e4SLinus Torvalds return NULL; 6831da177e4SLinus Torvalds } 6841da177e4SLinus Torvalds 685119bc547SMikulas Patocka static struct dm_exception *alloc_completed_exception(gfp_t gfp) 6861da177e4SLinus Torvalds { 6871d4989c8SJon Brassow struct dm_exception *e; 6881da177e4SLinus Torvalds 689119bc547SMikulas Patocka e = kmem_cache_alloc(exception_cache, gfp); 690119bc547SMikulas Patocka if (!e && gfp == GFP_NOIO) 6911da177e4SLinus Torvalds e = kmem_cache_alloc(exception_cache, GFP_ATOMIC); 6921da177e4SLinus Torvalds 6931da177e4SLinus Torvalds return e; 6941da177e4SLinus Torvalds } 6951da177e4SLinus Torvalds 6963510cb94SJon Brassow static void free_completed_exception(struct dm_exception *e) 6971da177e4SLinus Torvalds { 6981da177e4SLinus Torvalds kmem_cache_free(exception_cache, e); 6991da177e4SLinus Torvalds } 7001da177e4SLinus Torvalds 70192e86812SMikulas Patocka static struct dm_snap_pending_exception *alloc_pending_exception(struct dm_snapshot *s) 7021da177e4SLinus Torvalds { 7036f1c819cSKent Overstreet struct dm_snap_pending_exception *pe = mempool_alloc(&s->pending_pool, 70492e86812SMikulas Patocka GFP_NOIO); 70592e86812SMikulas Patocka 706879129d2SMikulas Patocka atomic_inc(&s->pending_exceptions_count); 70792e86812SMikulas Patocka pe->snap = s; 70892e86812SMikulas Patocka 70992e86812SMikulas Patocka return pe; 7101da177e4SLinus Torvalds } 7111da177e4SLinus Torvalds 712028867acSAlasdair G Kergon static void free_pending_exception(struct dm_snap_pending_exception *pe) 7131da177e4SLinus Torvalds { 714879129d2SMikulas Patocka struct dm_snapshot *s = pe->snap; 715879129d2SMikulas Patocka 7166f1c819cSKent Overstreet mempool_free(pe, &s->pending_pool); 7174e857c58SPeter Zijlstra smp_mb__before_atomic(); 718879129d2SMikulas Patocka atomic_dec(&s->pending_exceptions_count); 7191da177e4SLinus Torvalds } 7201da177e4SLinus Torvalds 7213510cb94SJon Brassow static void dm_insert_exception(struct dm_exception_table *eh, 7221d4989c8SJon Brassow struct dm_exception *new_e) 723d74f81f8SMilan Broz { 724d74f81f8SMilan Broz struct list_head *l; 7251d4989c8SJon Brassow struct dm_exception *e = NULL; 726d74f81f8SMilan Broz 727d74f81f8SMilan Broz l = &eh->table[exception_hash(eh, new_e->old_chunk)]; 728d74f81f8SMilan Broz 729d74f81f8SMilan Broz /* Add immediately if this table doesn't support consecutive chunks */ 730d74f81f8SMilan Broz if (!eh->hash_shift) 731d74f81f8SMilan Broz goto out; 732d74f81f8SMilan Broz 733d74f81f8SMilan Broz /* List is ordered by old_chunk */ 734d74f81f8SMilan Broz list_for_each_entry_reverse(e, l, hash_list) { 735d74f81f8SMilan Broz /* Insert after an existing chunk? */ 736d74f81f8SMilan Broz if (new_e->old_chunk == (e->old_chunk + 737d74f81f8SMilan Broz dm_consecutive_chunk_count(e) + 1) && 738d74f81f8SMilan Broz new_e->new_chunk == (dm_chunk_number(e->new_chunk) + 739d74f81f8SMilan Broz dm_consecutive_chunk_count(e) + 1)) { 740d74f81f8SMilan Broz dm_consecutive_chunk_count_inc(e); 7413510cb94SJon Brassow free_completed_exception(new_e); 742d74f81f8SMilan Broz return; 743d74f81f8SMilan Broz } 744d74f81f8SMilan Broz 745d74f81f8SMilan Broz /* Insert before an existing chunk? */ 746d74f81f8SMilan Broz if (new_e->old_chunk == (e->old_chunk - 1) && 747d74f81f8SMilan Broz new_e->new_chunk == (dm_chunk_number(e->new_chunk) - 1)) { 748d74f81f8SMilan Broz dm_consecutive_chunk_count_inc(e); 749d74f81f8SMilan Broz e->old_chunk--; 750d74f81f8SMilan Broz e->new_chunk--; 7513510cb94SJon Brassow free_completed_exception(new_e); 752d74f81f8SMilan Broz return; 753d74f81f8SMilan Broz } 754d74f81f8SMilan Broz 755d74f81f8SMilan Broz if (new_e->old_chunk > e->old_chunk) 756d74f81f8SMilan Broz break; 757d74f81f8SMilan Broz } 758d74f81f8SMilan Broz 759d74f81f8SMilan Broz out: 760d74f81f8SMilan Broz list_add(&new_e->hash_list, e ? &e->hash_list : l); 761d74f81f8SMilan Broz } 762d74f81f8SMilan Broz 763a159c1acSJonathan Brassow /* 764a159c1acSJonathan Brassow * Callback used by the exception stores to load exceptions when 765a159c1acSJonathan Brassow * initialising. 766a159c1acSJonathan Brassow */ 767a159c1acSJonathan Brassow static int dm_add_exception(void *context, chunk_t old, chunk_t new) 7681da177e4SLinus Torvalds { 769a159c1acSJonathan Brassow struct dm_snapshot *s = context; 7701d4989c8SJon Brassow struct dm_exception *e; 7711da177e4SLinus Torvalds 772119bc547SMikulas Patocka e = alloc_completed_exception(GFP_KERNEL); 7731da177e4SLinus Torvalds if (!e) 7741da177e4SLinus Torvalds return -ENOMEM; 7751da177e4SLinus Torvalds 7761da177e4SLinus Torvalds e->old_chunk = old; 777d74f81f8SMilan Broz 778d74f81f8SMilan Broz /* Consecutive_count is implicitly initialised to zero */ 7791da177e4SLinus Torvalds e->new_chunk = new; 780d74f81f8SMilan Broz 7813510cb94SJon Brassow dm_insert_exception(&s->complete, e); 782d74f81f8SMilan Broz 7831da177e4SLinus Torvalds return 0; 7841da177e4SLinus Torvalds } 7851da177e4SLinus Torvalds 7867e201b35SMikulas Patocka /* 7877e201b35SMikulas Patocka * Return a minimum chunk size of all snapshots that have the specified origin. 7887e201b35SMikulas Patocka * Return zero if the origin has no snapshots. 7897e201b35SMikulas Patocka */ 790542f9038SMike Snitzer static uint32_t __minimum_chunk_size(struct origin *o) 7917e201b35SMikulas Patocka { 7927e201b35SMikulas Patocka struct dm_snapshot *snap; 7937e201b35SMikulas Patocka unsigned chunk_size = 0; 7947e201b35SMikulas Patocka 7957e201b35SMikulas Patocka if (o) 7967e201b35SMikulas Patocka list_for_each_entry(snap, &o->snapshots, list) 7977e201b35SMikulas Patocka chunk_size = min_not_zero(chunk_size, 7987e201b35SMikulas Patocka snap->store->chunk_size); 7997e201b35SMikulas Patocka 800542f9038SMike Snitzer return (uint32_t) chunk_size; 8017e201b35SMikulas Patocka } 8027e201b35SMikulas Patocka 8031da177e4SLinus Torvalds /* 8041da177e4SLinus Torvalds * Hard coded magic. 8051da177e4SLinus Torvalds */ 8061da177e4SLinus Torvalds static int calc_max_buckets(void) 8071da177e4SLinus Torvalds { 8081da177e4SLinus Torvalds /* use a fixed size of 2MB */ 8091da177e4SLinus Torvalds unsigned long mem = 2 * 1024 * 1024; 8101da177e4SLinus Torvalds mem /= sizeof(struct list_head); 8111da177e4SLinus Torvalds 8121da177e4SLinus Torvalds return mem; 8131da177e4SLinus Torvalds } 8141da177e4SLinus Torvalds 8151da177e4SLinus Torvalds /* 8161da177e4SLinus Torvalds * Allocate room for a suitable hash table. 8171da177e4SLinus Torvalds */ 818fee1998eSJonathan Brassow static int init_hash_tables(struct dm_snapshot *s) 8191da177e4SLinus Torvalds { 82060e356f3SMikulas Patocka sector_t hash_size, cow_dev_size, max_buckets; 8211da177e4SLinus Torvalds 8221da177e4SLinus Torvalds /* 8231da177e4SLinus Torvalds * Calculate based on the size of the original volume or 8241da177e4SLinus Torvalds * the COW volume... 8251da177e4SLinus Torvalds */ 826fc56f6fbSMike Snitzer cow_dev_size = get_dev_size(s->cow->bdev); 8271da177e4SLinus Torvalds max_buckets = calc_max_buckets(); 8281da177e4SLinus Torvalds 82960e356f3SMikulas Patocka hash_size = cow_dev_size >> s->store->chunk_shift; 8301da177e4SLinus Torvalds hash_size = min(hash_size, max_buckets); 8311da177e4SLinus Torvalds 8328e87b9b8SMikulas Patocka if (hash_size < 64) 8338e87b9b8SMikulas Patocka hash_size = 64; 8348defd830SRobert P. J. Day hash_size = rounddown_pow_of_two(hash_size); 8353510cb94SJon Brassow if (dm_exception_table_init(&s->complete, hash_size, 836d74f81f8SMilan Broz DM_CHUNK_CONSECUTIVE_BITS)) 8371da177e4SLinus Torvalds return -ENOMEM; 8381da177e4SLinus Torvalds 8391da177e4SLinus Torvalds /* 8401da177e4SLinus Torvalds * Allocate hash table for in-flight exceptions 8411da177e4SLinus Torvalds * Make this smaller than the real hash table 8421da177e4SLinus Torvalds */ 8431da177e4SLinus Torvalds hash_size >>= 3; 8441da177e4SLinus Torvalds if (hash_size < 64) 8451da177e4SLinus Torvalds hash_size = 64; 8461da177e4SLinus Torvalds 8473510cb94SJon Brassow if (dm_exception_table_init(&s->pending, hash_size, 0)) { 8483510cb94SJon Brassow dm_exception_table_exit(&s->complete, exception_cache); 8491da177e4SLinus Torvalds return -ENOMEM; 8501da177e4SLinus Torvalds } 8511da177e4SLinus Torvalds 8521da177e4SLinus Torvalds return 0; 8531da177e4SLinus Torvalds } 8541da177e4SLinus Torvalds 8551e03f97eSMikulas Patocka static void merge_shutdown(struct dm_snapshot *s) 8561e03f97eSMikulas Patocka { 8571e03f97eSMikulas Patocka clear_bit_unlock(RUNNING_MERGE, &s->state_bits); 8584e857c58SPeter Zijlstra smp_mb__after_atomic(); 8591e03f97eSMikulas Patocka wake_up_bit(&s->state_bits, RUNNING_MERGE); 8601e03f97eSMikulas Patocka } 8611e03f97eSMikulas Patocka 8629fe86254SMikulas Patocka static struct bio *__release_queued_bios_after_merge(struct dm_snapshot *s) 8639fe86254SMikulas Patocka { 8649fe86254SMikulas Patocka s->first_merging_chunk = 0; 8659fe86254SMikulas Patocka s->num_merging_chunks = 0; 8669fe86254SMikulas Patocka 8679fe86254SMikulas Patocka return bio_list_get(&s->bios_queued_during_merge); 8689fe86254SMikulas Patocka } 8699fe86254SMikulas Patocka 8701e03f97eSMikulas Patocka /* 8711e03f97eSMikulas Patocka * Remove one chunk from the index of completed exceptions. 8721e03f97eSMikulas Patocka */ 8731e03f97eSMikulas Patocka static int __remove_single_exception_chunk(struct dm_snapshot *s, 8741e03f97eSMikulas Patocka chunk_t old_chunk) 8751e03f97eSMikulas Patocka { 8761e03f97eSMikulas Patocka struct dm_exception *e; 8771e03f97eSMikulas Patocka 8781e03f97eSMikulas Patocka e = dm_lookup_exception(&s->complete, old_chunk); 8791e03f97eSMikulas Patocka if (!e) { 8801e03f97eSMikulas Patocka DMERR("Corruption detected: exception for block %llu is " 8811e03f97eSMikulas Patocka "on disk but not in memory", 8821e03f97eSMikulas Patocka (unsigned long long)old_chunk); 8831e03f97eSMikulas Patocka return -EINVAL; 8841e03f97eSMikulas Patocka } 8851e03f97eSMikulas Patocka 8861e03f97eSMikulas Patocka /* 8871e03f97eSMikulas Patocka * If this is the only chunk using this exception, remove exception. 8881e03f97eSMikulas Patocka */ 8891e03f97eSMikulas Patocka if (!dm_consecutive_chunk_count(e)) { 8901e03f97eSMikulas Patocka dm_remove_exception(e); 8911e03f97eSMikulas Patocka free_completed_exception(e); 8921e03f97eSMikulas Patocka return 0; 8931e03f97eSMikulas Patocka } 8941e03f97eSMikulas Patocka 8951e03f97eSMikulas Patocka /* 8961e03f97eSMikulas Patocka * The chunk may be either at the beginning or the end of a 8971e03f97eSMikulas Patocka * group of consecutive chunks - never in the middle. We are 8981e03f97eSMikulas Patocka * removing chunks in the opposite order to that in which they 8991e03f97eSMikulas Patocka * were added, so this should always be true. 9001e03f97eSMikulas Patocka * Decrement the consecutive chunk counter and adjust the 9011e03f97eSMikulas Patocka * starting point if necessary. 9021e03f97eSMikulas Patocka */ 9031e03f97eSMikulas Patocka if (old_chunk == e->old_chunk) { 9041e03f97eSMikulas Patocka e->old_chunk++; 9051e03f97eSMikulas Patocka e->new_chunk++; 9061e03f97eSMikulas Patocka } else if (old_chunk != e->old_chunk + 9071e03f97eSMikulas Patocka dm_consecutive_chunk_count(e)) { 9081e03f97eSMikulas Patocka DMERR("Attempt to merge block %llu from the " 9091e03f97eSMikulas Patocka "middle of a chunk range [%llu - %llu]", 9101e03f97eSMikulas Patocka (unsigned long long)old_chunk, 9111e03f97eSMikulas Patocka (unsigned long long)e->old_chunk, 9121e03f97eSMikulas Patocka (unsigned long long) 9131e03f97eSMikulas Patocka e->old_chunk + dm_consecutive_chunk_count(e)); 9141e03f97eSMikulas Patocka return -EINVAL; 9151e03f97eSMikulas Patocka } 9161e03f97eSMikulas Patocka 9171e03f97eSMikulas Patocka dm_consecutive_chunk_count_dec(e); 9181e03f97eSMikulas Patocka 9191e03f97eSMikulas Patocka return 0; 9201e03f97eSMikulas Patocka } 9211e03f97eSMikulas Patocka 9229fe86254SMikulas Patocka static void flush_bios(struct bio *bio); 9239fe86254SMikulas Patocka 9249fe86254SMikulas Patocka static int remove_single_exception_chunk(struct dm_snapshot *s) 9251e03f97eSMikulas Patocka { 9269fe86254SMikulas Patocka struct bio *b = NULL; 9279fe86254SMikulas Patocka int r; 9289fe86254SMikulas Patocka chunk_t old_chunk = s->first_merging_chunk + s->num_merging_chunks - 1; 9291e03f97eSMikulas Patocka 930ae1093beSMikulas Patocka mutex_lock(&s->lock); 9319fe86254SMikulas Patocka 9329fe86254SMikulas Patocka /* 9339fe86254SMikulas Patocka * Process chunks (and associated exceptions) in reverse order 9349fe86254SMikulas Patocka * so that dm_consecutive_chunk_count_dec() accounting works. 9359fe86254SMikulas Patocka */ 9369fe86254SMikulas Patocka do { 9371e03f97eSMikulas Patocka r = __remove_single_exception_chunk(s, old_chunk); 9389fe86254SMikulas Patocka if (r) 9399fe86254SMikulas Patocka goto out; 9409fe86254SMikulas Patocka } while (old_chunk-- > s->first_merging_chunk); 9419fe86254SMikulas Patocka 9429fe86254SMikulas Patocka b = __release_queued_bios_after_merge(s); 9439fe86254SMikulas Patocka 9449fe86254SMikulas Patocka out: 945ae1093beSMikulas Patocka mutex_unlock(&s->lock); 9469fe86254SMikulas Patocka if (b) 9479fe86254SMikulas Patocka flush_bios(b); 9481e03f97eSMikulas Patocka 9491e03f97eSMikulas Patocka return r; 9501e03f97eSMikulas Patocka } 9511e03f97eSMikulas Patocka 95273dfd078SMikulas Patocka static int origin_write_extent(struct dm_snapshot *merging_snap, 95373dfd078SMikulas Patocka sector_t sector, unsigned chunk_size); 95473dfd078SMikulas Patocka 9551e03f97eSMikulas Patocka static void merge_callback(int read_err, unsigned long write_err, 9561e03f97eSMikulas Patocka void *context); 9571e03f97eSMikulas Patocka 95873dfd078SMikulas Patocka static uint64_t read_pending_exceptions_done_count(void) 95973dfd078SMikulas Patocka { 96073dfd078SMikulas Patocka uint64_t pending_exceptions_done; 96173dfd078SMikulas Patocka 96273dfd078SMikulas Patocka spin_lock(&_pending_exceptions_done_spinlock); 96373dfd078SMikulas Patocka pending_exceptions_done = _pending_exceptions_done_count; 96473dfd078SMikulas Patocka spin_unlock(&_pending_exceptions_done_spinlock); 96573dfd078SMikulas Patocka 96673dfd078SMikulas Patocka return pending_exceptions_done; 96773dfd078SMikulas Patocka } 96873dfd078SMikulas Patocka 96973dfd078SMikulas Patocka static void increment_pending_exceptions_done_count(void) 97073dfd078SMikulas Patocka { 97173dfd078SMikulas Patocka spin_lock(&_pending_exceptions_done_spinlock); 97273dfd078SMikulas Patocka _pending_exceptions_done_count++; 97373dfd078SMikulas Patocka spin_unlock(&_pending_exceptions_done_spinlock); 97473dfd078SMikulas Patocka 97573dfd078SMikulas Patocka wake_up_all(&_pending_exceptions_done); 97673dfd078SMikulas Patocka } 97773dfd078SMikulas Patocka 9781e03f97eSMikulas Patocka static void snapshot_merge_next_chunks(struct dm_snapshot *s) 9791e03f97eSMikulas Patocka { 9808a2d5286SMike Snitzer int i, linear_chunks; 9811e03f97eSMikulas Patocka chunk_t old_chunk, new_chunk; 9821e03f97eSMikulas Patocka struct dm_io_region src, dest; 9838a2d5286SMike Snitzer sector_t io_size; 98473dfd078SMikulas Patocka uint64_t previous_count; 9851e03f97eSMikulas Patocka 9861e03f97eSMikulas Patocka BUG_ON(!test_bit(RUNNING_MERGE, &s->state_bits)); 9871e03f97eSMikulas Patocka if (unlikely(test_bit(SHUTDOWN_MERGE, &s->state_bits))) 9881e03f97eSMikulas Patocka goto shut; 9891e03f97eSMikulas Patocka 9901e03f97eSMikulas Patocka /* 9911e03f97eSMikulas Patocka * valid flag never changes during merge, so no lock required. 9921e03f97eSMikulas Patocka */ 9931e03f97eSMikulas Patocka if (!s->valid) { 9941e03f97eSMikulas Patocka DMERR("Snapshot is invalid: can't merge"); 9951e03f97eSMikulas Patocka goto shut; 9961e03f97eSMikulas Patocka } 9971e03f97eSMikulas Patocka 9988a2d5286SMike Snitzer linear_chunks = s->store->type->prepare_merge(s->store, &old_chunk, 9998a2d5286SMike Snitzer &new_chunk); 10008a2d5286SMike Snitzer if (linear_chunks <= 0) { 1001d8ddb1cfSMike Snitzer if (linear_chunks < 0) { 10021e03f97eSMikulas Patocka DMERR("Read error in exception store: " 10031e03f97eSMikulas Patocka "shutting down merge"); 1004ae1093beSMikulas Patocka mutex_lock(&s->lock); 1005d8ddb1cfSMike Snitzer s->merge_failed = 1; 1006ae1093beSMikulas Patocka mutex_unlock(&s->lock); 1007d8ddb1cfSMike Snitzer } 10081e03f97eSMikulas Patocka goto shut; 10091e03f97eSMikulas Patocka } 10101e03f97eSMikulas Patocka 10118a2d5286SMike Snitzer /* Adjust old_chunk and new_chunk to reflect start of linear region */ 10128a2d5286SMike Snitzer old_chunk = old_chunk + 1 - linear_chunks; 10138a2d5286SMike Snitzer new_chunk = new_chunk + 1 - linear_chunks; 10148a2d5286SMike Snitzer 10158a2d5286SMike Snitzer /* 10168a2d5286SMike Snitzer * Use one (potentially large) I/O to copy all 'linear_chunks' 10178a2d5286SMike Snitzer * from the exception store to the origin 10188a2d5286SMike Snitzer */ 10198a2d5286SMike Snitzer io_size = linear_chunks * s->store->chunk_size; 10201e03f97eSMikulas Patocka 10211e03f97eSMikulas Patocka dest.bdev = s->origin->bdev; 10221e03f97eSMikulas Patocka dest.sector = chunk_to_sector(s->store, old_chunk); 10238a2d5286SMike Snitzer dest.count = min(io_size, get_dev_size(dest.bdev) - dest.sector); 10241e03f97eSMikulas Patocka 10251e03f97eSMikulas Patocka src.bdev = s->cow->bdev; 10261e03f97eSMikulas Patocka src.sector = chunk_to_sector(s->store, new_chunk); 10271e03f97eSMikulas Patocka src.count = dest.count; 10281e03f97eSMikulas Patocka 102973dfd078SMikulas Patocka /* 103073dfd078SMikulas Patocka * Reallocate any exceptions needed in other snapshots then 103173dfd078SMikulas Patocka * wait for the pending exceptions to complete. 103273dfd078SMikulas Patocka * Each time any pending exception (globally on the system) 103373dfd078SMikulas Patocka * completes we are woken and repeat the process to find out 103473dfd078SMikulas Patocka * if we can proceed. While this may not seem a particularly 103573dfd078SMikulas Patocka * efficient algorithm, it is not expected to have any 103673dfd078SMikulas Patocka * significant impact on performance. 103773dfd078SMikulas Patocka */ 103873dfd078SMikulas Patocka previous_count = read_pending_exceptions_done_count(); 10398a2d5286SMike Snitzer while (origin_write_extent(s, dest.sector, io_size)) { 104073dfd078SMikulas Patocka wait_event(_pending_exceptions_done, 104173dfd078SMikulas Patocka (read_pending_exceptions_done_count() != 104273dfd078SMikulas Patocka previous_count)); 104373dfd078SMikulas Patocka /* Retry after the wait, until all exceptions are done. */ 104473dfd078SMikulas Patocka previous_count = read_pending_exceptions_done_count(); 104573dfd078SMikulas Patocka } 104673dfd078SMikulas Patocka 1047ae1093beSMikulas Patocka mutex_lock(&s->lock); 10489fe86254SMikulas Patocka s->first_merging_chunk = old_chunk; 10498a2d5286SMike Snitzer s->num_merging_chunks = linear_chunks; 1050ae1093beSMikulas Patocka mutex_unlock(&s->lock); 10519fe86254SMikulas Patocka 10528a2d5286SMike Snitzer /* Wait until writes to all 'linear_chunks' drain */ 10538a2d5286SMike Snitzer for (i = 0; i < linear_chunks; i++) 10548a2d5286SMike Snitzer __check_for_conflicting_io(s, old_chunk + i); 10559fe86254SMikulas Patocka 10561e03f97eSMikulas Patocka dm_kcopyd_copy(s->kcopyd_client, &src, 1, &dest, 0, merge_callback, s); 10571e03f97eSMikulas Patocka return; 10581e03f97eSMikulas Patocka 10591e03f97eSMikulas Patocka shut: 10601e03f97eSMikulas Patocka merge_shutdown(s); 10611e03f97eSMikulas Patocka } 10621e03f97eSMikulas Patocka 10639fe86254SMikulas Patocka static void error_bios(struct bio *bio); 10649fe86254SMikulas Patocka 10651e03f97eSMikulas Patocka static void merge_callback(int read_err, unsigned long write_err, void *context) 10661e03f97eSMikulas Patocka { 10671e03f97eSMikulas Patocka struct dm_snapshot *s = context; 10689fe86254SMikulas Patocka struct bio *b = NULL; 10691e03f97eSMikulas Patocka 10701e03f97eSMikulas Patocka if (read_err || write_err) { 10711e03f97eSMikulas Patocka if (read_err) 10721e03f97eSMikulas Patocka DMERR("Read error: shutting down merge."); 10731e03f97eSMikulas Patocka else 10741e03f97eSMikulas Patocka DMERR("Write error: shutting down merge."); 10751e03f97eSMikulas Patocka goto shut; 10761e03f97eSMikulas Patocka } 10771e03f97eSMikulas Patocka 10789fe86254SMikulas Patocka if (s->store->type->commit_merge(s->store, 10799fe86254SMikulas Patocka s->num_merging_chunks) < 0) { 10801e03f97eSMikulas Patocka DMERR("Write error in exception store: shutting down merge"); 10811e03f97eSMikulas Patocka goto shut; 10821e03f97eSMikulas Patocka } 10831e03f97eSMikulas Patocka 10849fe86254SMikulas Patocka if (remove_single_exception_chunk(s) < 0) 10859fe86254SMikulas Patocka goto shut; 10869fe86254SMikulas Patocka 10871e03f97eSMikulas Patocka snapshot_merge_next_chunks(s); 10881e03f97eSMikulas Patocka 10891e03f97eSMikulas Patocka return; 10901e03f97eSMikulas Patocka 10911e03f97eSMikulas Patocka shut: 1092ae1093beSMikulas Patocka mutex_lock(&s->lock); 1093d8ddb1cfSMike Snitzer s->merge_failed = 1; 10949fe86254SMikulas Patocka b = __release_queued_bios_after_merge(s); 1095ae1093beSMikulas Patocka mutex_unlock(&s->lock); 10969fe86254SMikulas Patocka error_bios(b); 10979fe86254SMikulas Patocka 10981e03f97eSMikulas Patocka merge_shutdown(s); 10991e03f97eSMikulas Patocka } 11001e03f97eSMikulas Patocka 11011e03f97eSMikulas Patocka static void start_merge(struct dm_snapshot *s) 11021e03f97eSMikulas Patocka { 11031e03f97eSMikulas Patocka if (!test_and_set_bit(RUNNING_MERGE, &s->state_bits)) 11041e03f97eSMikulas Patocka snapshot_merge_next_chunks(s); 11051e03f97eSMikulas Patocka } 11061e03f97eSMikulas Patocka 11071e03f97eSMikulas Patocka /* 11081e03f97eSMikulas Patocka * Stop the merging process and wait until it finishes. 11091e03f97eSMikulas Patocka */ 11101e03f97eSMikulas Patocka static void stop_merge(struct dm_snapshot *s) 11111e03f97eSMikulas Patocka { 11121e03f97eSMikulas Patocka set_bit(SHUTDOWN_MERGE, &s->state_bits); 111374316201SNeilBrown wait_on_bit(&s->state_bits, RUNNING_MERGE, TASK_UNINTERRUPTIBLE); 11141e03f97eSMikulas Patocka clear_bit(SHUTDOWN_MERGE, &s->state_bits); 11151e03f97eSMikulas Patocka } 11161e03f97eSMikulas Patocka 11171da177e4SLinus Torvalds /* 1118b0d3cc01SMike Snitzer * Construct a snapshot mapping: <origin_dev> <COW-dev> <p|po|n> <chunk-size> 11191da177e4SLinus Torvalds */ 11201da177e4SLinus Torvalds static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv) 11211da177e4SLinus Torvalds { 11221da177e4SLinus Torvalds struct dm_snapshot *s; 1123cd45daffSMikulas Patocka int i; 11241da177e4SLinus Torvalds int r = -EINVAL; 1125fc56f6fbSMike Snitzer char *origin_path, *cow_path; 11264df2bf46SDingXiang dev_t origin_dev, cow_dev; 112755a62eefSAlasdair G Kergon unsigned args_used, num_flush_bios = 1; 112810b8106aSMike Snitzer fmode_t origin_mode = FMODE_READ; 11291da177e4SLinus Torvalds 11304c7e3bf4SMark McLoughlin if (argc != 4) { 113172d94861SAlasdair G Kergon ti->error = "requires exactly 4 arguments"; 11321da177e4SLinus Torvalds r = -EINVAL; 1133fc56f6fbSMike Snitzer goto bad; 11341da177e4SLinus Torvalds } 11351da177e4SLinus Torvalds 113610b8106aSMike Snitzer if (dm_target_is_snapshot_merge(ti)) { 113755a62eefSAlasdair G Kergon num_flush_bios = 2; 113810b8106aSMike Snitzer origin_mode = FMODE_WRITE; 113910b8106aSMike Snitzer } 114010b8106aSMike Snitzer 1141d3775354SKent Overstreet s = kzalloc(sizeof(*s), GFP_KERNEL); 1142fee1998eSJonathan Brassow if (!s) { 1143a2d2b034SJonathan Brassow ti->error = "Cannot allocate private snapshot structure"; 11441da177e4SLinus Torvalds r = -ENOMEM; 1145fc56f6fbSMike Snitzer goto bad; 11461da177e4SLinus Torvalds } 11471da177e4SLinus Torvalds 1148c2411045SMikulas Patocka origin_path = argv[0]; 1149c2411045SMikulas Patocka argv++; 1150c2411045SMikulas Patocka argc--; 1151c2411045SMikulas Patocka 1152c2411045SMikulas Patocka r = dm_get_device(ti, origin_path, origin_mode, &s->origin); 1153c2411045SMikulas Patocka if (r) { 1154c2411045SMikulas Patocka ti->error = "Cannot get origin device"; 1155c2411045SMikulas Patocka goto bad_origin; 1156c2411045SMikulas Patocka } 11574df2bf46SDingXiang origin_dev = s->origin->bdev->bd_dev; 1158c2411045SMikulas Patocka 1159fc56f6fbSMike Snitzer cow_path = argv[0]; 1160fc56f6fbSMike Snitzer argv++; 1161fc56f6fbSMike Snitzer argc--; 1162fc56f6fbSMike Snitzer 11634df2bf46SDingXiang cow_dev = dm_get_dev_t(cow_path); 11644df2bf46SDingXiang if (cow_dev && cow_dev == origin_dev) { 11654df2bf46SDingXiang ti->error = "COW device cannot be the same as origin device"; 11664df2bf46SDingXiang r = -EINVAL; 11674df2bf46SDingXiang goto bad_cow; 11684df2bf46SDingXiang } 11694df2bf46SDingXiang 1170024d37e9SMilan Broz r = dm_get_device(ti, cow_path, dm_table_get_mode(ti->table), &s->cow); 1171fc56f6fbSMike Snitzer if (r) { 1172fc56f6fbSMike Snitzer ti->error = "Cannot get COW device"; 1173fc56f6fbSMike Snitzer goto bad_cow; 1174fc56f6fbSMike Snitzer } 1175fc56f6fbSMike Snitzer 1176fc56f6fbSMike Snitzer r = dm_exception_store_create(ti, argc, argv, s, &args_used, &s->store); 1177fc56f6fbSMike Snitzer if (r) { 1178fc56f6fbSMike Snitzer ti->error = "Couldn't create exception store"; 1179fc56f6fbSMike Snitzer r = -EINVAL; 1180fc56f6fbSMike Snitzer goto bad_store; 1181fc56f6fbSMike Snitzer } 1182fc56f6fbSMike Snitzer 1183fc56f6fbSMike Snitzer argv += args_used; 1184fc56f6fbSMike Snitzer argc -= args_used; 1185fc56f6fbSMike Snitzer 1186fc56f6fbSMike Snitzer s->ti = ti; 11871da177e4SLinus Torvalds s->valid = 1; 118876c44f6dSMikulas Patocka s->snapshot_overflowed = 0; 1189aa14edebSAlasdair G Kergon s->active = 0; 1190879129d2SMikulas Patocka atomic_set(&s->pending_exceptions_count, 0); 1191230c83afSMikulas Patocka s->exception_start_sequence = 0; 1192230c83afSMikulas Patocka s->exception_complete_sequence = 0; 11933db2776dSDavid Jeffery s->out_of_order_tree = RB_ROOT; 1194ae1093beSMikulas Patocka mutex_init(&s->lock); 1195c1f0c183SMike Snitzer INIT_LIST_HEAD(&s->list); 1196ca3a931fSAlasdair G Kergon spin_lock_init(&s->pe_lock); 11971e03f97eSMikulas Patocka s->state_bits = 0; 1198d8ddb1cfSMike Snitzer s->merge_failed = 0; 11999fe86254SMikulas Patocka s->first_merging_chunk = 0; 12009fe86254SMikulas Patocka s->num_merging_chunks = 0; 12019fe86254SMikulas Patocka bio_list_init(&s->bios_queued_during_merge); 12021da177e4SLinus Torvalds 12031da177e4SLinus Torvalds /* Allocate hash table for COW data */ 1204fee1998eSJonathan Brassow if (init_hash_tables(s)) { 12051da177e4SLinus Torvalds ti->error = "Unable to allocate hash table space"; 12061da177e4SLinus Torvalds r = -ENOMEM; 1207fee1998eSJonathan Brassow goto bad_hash_tables; 12081da177e4SLinus Torvalds } 12091da177e4SLinus Torvalds 1210721b1d98SNikos Tsironis sema_init(&s->cow_count, (cow_threshold > 0) ? cow_threshold : INT_MAX); 1211721b1d98SNikos Tsironis 1212df5d2e90SMikulas Patocka s->kcopyd_client = dm_kcopyd_client_create(&dm_kcopyd_throttle); 1213fa34ce73SMikulas Patocka if (IS_ERR(s->kcopyd_client)) { 1214fa34ce73SMikulas Patocka r = PTR_ERR(s->kcopyd_client); 12151da177e4SLinus Torvalds ti->error = "Could not create kcopyd client"; 1216fee1998eSJonathan Brassow goto bad_kcopyd; 12171da177e4SLinus Torvalds } 12181da177e4SLinus Torvalds 12196f1c819cSKent Overstreet r = mempool_init_slab_pool(&s->pending_pool, MIN_IOS, pending_cache); 12206f1c819cSKent Overstreet if (r) { 122192e86812SMikulas Patocka ti->error = "Could not allocate mempool for pending exceptions"; 1222fee1998eSJonathan Brassow goto bad_pending_pool; 122392e86812SMikulas Patocka } 122492e86812SMikulas Patocka 1225cd45daffSMikulas Patocka for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) 1226cd45daffSMikulas Patocka INIT_HLIST_HEAD(&s->tracked_chunk_hash[i]); 1227cd45daffSMikulas Patocka 1228cd45daffSMikulas Patocka spin_lock_init(&s->tracked_chunk_lock); 1229cd45daffSMikulas Patocka 1230c1f0c183SMike Snitzer ti->private = s; 123155a62eefSAlasdair G Kergon ti->num_flush_bios = num_flush_bios; 123230187e1dSMike Snitzer ti->per_io_data_size = sizeof(struct dm_snap_tracked_chunk); 1233c1f0c183SMike Snitzer 1234c1f0c183SMike Snitzer /* Add snapshot to the list of snapshots for this origin */ 1235c1f0c183SMike Snitzer /* Exceptions aren't triggered till snapshot_resume() is called */ 1236c1f0c183SMike Snitzer r = register_snapshot(s); 1237c1f0c183SMike Snitzer if (r == -ENOMEM) { 1238c1f0c183SMike Snitzer ti->error = "Snapshot origin struct allocation failed"; 1239c1f0c183SMike Snitzer goto bad_load_and_register; 1240c1f0c183SMike Snitzer } else if (r < 0) { 1241c1f0c183SMike Snitzer /* invalid handover, register_snapshot has set ti->error */ 1242c1f0c183SMike Snitzer goto bad_load_and_register; 1243c1f0c183SMike Snitzer } 1244c1f0c183SMike Snitzer 1245c1f0c183SMike Snitzer /* 1246c1f0c183SMike Snitzer * Metadata must only be loaded into one table at once, so skip this 1247c1f0c183SMike Snitzer * if metadata will be handed over during resume. 1248c1f0c183SMike Snitzer * Chunk size will be set during the handover - set it to zero to 1249c1f0c183SMike Snitzer * ensure it's ignored. 1250c1f0c183SMike Snitzer */ 1251c1f0c183SMike Snitzer if (r > 0) { 1252c1f0c183SMike Snitzer s->store->chunk_size = 0; 1253c1f0c183SMike Snitzer return 0; 1254c1f0c183SMike Snitzer } 1255c1f0c183SMike Snitzer 1256493df71cSJonathan Brassow r = s->store->type->read_metadata(s->store, dm_add_exception, 1257493df71cSJonathan Brassow (void *)s); 12580764147bSMilan Broz if (r < 0) { 1259f9cea4f7SMark McLoughlin ti->error = "Failed to read snapshot metadata"; 1260c1f0c183SMike Snitzer goto bad_read_metadata; 12610764147bSMilan Broz } else if (r > 0) { 12620764147bSMilan Broz s->valid = 0; 12630764147bSMilan Broz DMWARN("Snapshot is marked invalid."); 1264f9cea4f7SMark McLoughlin } 1265aa14edebSAlasdair G Kergon 12663f2412dcSMikulas Patocka if (!s->store->chunk_size) { 12673f2412dcSMikulas Patocka ti->error = "Chunk size not set"; 1268c1f0c183SMike Snitzer goto bad_read_metadata; 12693f2412dcSMikulas Patocka } 1270542f9038SMike Snitzer 1271542f9038SMike Snitzer r = dm_set_target_max_io_len(ti, s->store->chunk_size); 1272542f9038SMike Snitzer if (r) 1273542f9038SMike Snitzer goto bad_read_metadata; 12741da177e4SLinus Torvalds 12751da177e4SLinus Torvalds return 0; 12761da177e4SLinus Torvalds 1277c1f0c183SMike Snitzer bad_read_metadata: 1278c1f0c183SMike Snitzer unregister_snapshot(s); 1279c1f0c183SMike Snitzer 1280cd45daffSMikulas Patocka bad_load_and_register: 12816f1c819cSKent Overstreet mempool_exit(&s->pending_pool); 128292e86812SMikulas Patocka 1283fee1998eSJonathan Brassow bad_pending_pool: 1284eb69aca5SHeinz Mauelshagen dm_kcopyd_client_destroy(s->kcopyd_client); 12851da177e4SLinus Torvalds 1286fee1998eSJonathan Brassow bad_kcopyd: 12873510cb94SJon Brassow dm_exception_table_exit(&s->pending, pending_cache); 12883510cb94SJon Brassow dm_exception_table_exit(&s->complete, exception_cache); 12891da177e4SLinus Torvalds 1290fee1998eSJonathan Brassow bad_hash_tables: 1291fc56f6fbSMike Snitzer dm_exception_store_destroy(s->store); 1292fc56f6fbSMike Snitzer 1293fc56f6fbSMike Snitzer bad_store: 1294fc56f6fbSMike Snitzer dm_put_device(ti, s->cow); 1295fc56f6fbSMike Snitzer 1296fc56f6fbSMike Snitzer bad_cow: 1297c2411045SMikulas Patocka dm_put_device(ti, s->origin); 1298c2411045SMikulas Patocka 1299c2411045SMikulas Patocka bad_origin: 13001da177e4SLinus Torvalds kfree(s); 13011da177e4SLinus Torvalds 1302fc56f6fbSMike Snitzer bad: 13031da177e4SLinus Torvalds return r; 13041da177e4SLinus Torvalds } 13051da177e4SLinus Torvalds 130631c93a0cSMilan Broz static void __free_exceptions(struct dm_snapshot *s) 130731c93a0cSMilan Broz { 1308eb69aca5SHeinz Mauelshagen dm_kcopyd_client_destroy(s->kcopyd_client); 130931c93a0cSMilan Broz s->kcopyd_client = NULL; 131031c93a0cSMilan Broz 13113510cb94SJon Brassow dm_exception_table_exit(&s->pending, pending_cache); 13123510cb94SJon Brassow dm_exception_table_exit(&s->complete, exception_cache); 131331c93a0cSMilan Broz } 131431c93a0cSMilan Broz 1315c1f0c183SMike Snitzer static void __handover_exceptions(struct dm_snapshot *snap_src, 1316c1f0c183SMike Snitzer struct dm_snapshot *snap_dest) 1317c1f0c183SMike Snitzer { 1318c1f0c183SMike Snitzer union { 1319c1f0c183SMike Snitzer struct dm_exception_table table_swap; 1320c1f0c183SMike Snitzer struct dm_exception_store *store_swap; 1321c1f0c183SMike Snitzer } u; 1322c1f0c183SMike Snitzer 1323c1f0c183SMike Snitzer /* 1324c1f0c183SMike Snitzer * Swap all snapshot context information between the two instances. 1325c1f0c183SMike Snitzer */ 1326c1f0c183SMike Snitzer u.table_swap = snap_dest->complete; 1327c1f0c183SMike Snitzer snap_dest->complete = snap_src->complete; 1328c1f0c183SMike Snitzer snap_src->complete = u.table_swap; 1329c1f0c183SMike Snitzer 1330c1f0c183SMike Snitzer u.store_swap = snap_dest->store; 1331c1f0c183SMike Snitzer snap_dest->store = snap_src->store; 1332b0d3cc01SMike Snitzer snap_dest->store->userspace_supports_overflow = u.store_swap->userspace_supports_overflow; 1333c1f0c183SMike Snitzer snap_src->store = u.store_swap; 1334c1f0c183SMike Snitzer 1335c1f0c183SMike Snitzer snap_dest->store->snap = snap_dest; 1336c1f0c183SMike Snitzer snap_src->store->snap = snap_src; 1337c1f0c183SMike Snitzer 1338542f9038SMike Snitzer snap_dest->ti->max_io_len = snap_dest->store->chunk_size; 1339c1f0c183SMike Snitzer snap_dest->valid = snap_src->valid; 134076c44f6dSMikulas Patocka snap_dest->snapshot_overflowed = snap_src->snapshot_overflowed; 1341c1f0c183SMike Snitzer 1342c1f0c183SMike Snitzer /* 1343c1f0c183SMike Snitzer * Set source invalid to ensure it receives no further I/O. 1344c1f0c183SMike Snitzer */ 1345c1f0c183SMike Snitzer snap_src->valid = 0; 1346c1f0c183SMike Snitzer } 1347c1f0c183SMike Snitzer 13481da177e4SLinus Torvalds static void snapshot_dtr(struct dm_target *ti) 13491da177e4SLinus Torvalds { 1350cd45daffSMikulas Patocka #ifdef CONFIG_DM_DEBUG 1351cd45daffSMikulas Patocka int i; 1352cd45daffSMikulas Patocka #endif 1353028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 1354c1f0c183SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 13551da177e4SLinus Torvalds 1356c1f0c183SMike Snitzer down_read(&_origins_lock); 1357c1f0c183SMike Snitzer /* Check whether exception handover must be cancelled */ 13589d3b15c4SMikulas Patocka (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); 1359c1f0c183SMike Snitzer if (snap_src && snap_dest && (s == snap_src)) { 1360ae1093beSMikulas Patocka mutex_lock(&snap_dest->lock); 1361c1f0c183SMike Snitzer snap_dest->valid = 0; 1362ae1093beSMikulas Patocka mutex_unlock(&snap_dest->lock); 1363c1f0c183SMike Snitzer DMERR("Cancelling snapshot handover."); 1364c1f0c183SMike Snitzer } 1365c1f0c183SMike Snitzer up_read(&_origins_lock); 1366c1f0c183SMike Snitzer 13671e03f97eSMikulas Patocka if (dm_target_is_snapshot_merge(ti)) 13681e03f97eSMikulas Patocka stop_merge(s); 13691e03f97eSMikulas Patocka 1370138728dcSAlasdair G Kergon /* Prevent further origin writes from using this snapshot. */ 1371138728dcSAlasdair G Kergon /* After this returns there can be no new kcopyd jobs. */ 13721da177e4SLinus Torvalds unregister_snapshot(s); 13731da177e4SLinus Torvalds 1374879129d2SMikulas Patocka while (atomic_read(&s->pending_exceptions_count)) 137590fa1527SMikulas Patocka msleep(1); 1376879129d2SMikulas Patocka /* 13776f1c819cSKent Overstreet * Ensure instructions in mempool_exit aren't reordered 1378879129d2SMikulas Patocka * before atomic_read. 1379879129d2SMikulas Patocka */ 1380879129d2SMikulas Patocka smp_mb(); 1381879129d2SMikulas Patocka 1382cd45daffSMikulas Patocka #ifdef CONFIG_DM_DEBUG 1383cd45daffSMikulas Patocka for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) 1384cd45daffSMikulas Patocka BUG_ON(!hlist_empty(&s->tracked_chunk_hash[i])); 1385cd45daffSMikulas Patocka #endif 1386cd45daffSMikulas Patocka 138731c93a0cSMilan Broz __free_exceptions(s); 13881da177e4SLinus Torvalds 13896f1c819cSKent Overstreet mempool_exit(&s->pending_pool); 139092e86812SMikulas Patocka 1391fee1998eSJonathan Brassow dm_exception_store_destroy(s->store); 1392138728dcSAlasdair G Kergon 1393ae1093beSMikulas Patocka mutex_destroy(&s->lock); 1394ae1093beSMikulas Patocka 1395fc56f6fbSMike Snitzer dm_put_device(ti, s->cow); 1396fc56f6fbSMike Snitzer 1397c2411045SMikulas Patocka dm_put_device(ti, s->origin); 1398c2411045SMikulas Patocka 13991da177e4SLinus Torvalds kfree(s); 14001da177e4SLinus Torvalds } 14011da177e4SLinus Torvalds 14021da177e4SLinus Torvalds /* 14031da177e4SLinus Torvalds * Flush a list of buffers. 14041da177e4SLinus Torvalds */ 14051da177e4SLinus Torvalds static void flush_bios(struct bio *bio) 14061da177e4SLinus Torvalds { 14071da177e4SLinus Torvalds struct bio *n; 14081da177e4SLinus Torvalds 14091da177e4SLinus Torvalds while (bio) { 14101da177e4SLinus Torvalds n = bio->bi_next; 14111da177e4SLinus Torvalds bio->bi_next = NULL; 14121da177e4SLinus Torvalds generic_make_request(bio); 14131da177e4SLinus Torvalds bio = n; 14141da177e4SLinus Torvalds } 14151da177e4SLinus Torvalds } 14161da177e4SLinus Torvalds 1417515ad66cSMikulas Patocka static int do_origin(struct dm_dev *origin, struct bio *bio); 1418515ad66cSMikulas Patocka 1419515ad66cSMikulas Patocka /* 1420515ad66cSMikulas Patocka * Flush a list of buffers. 1421515ad66cSMikulas Patocka */ 1422515ad66cSMikulas Patocka static void retry_origin_bios(struct dm_snapshot *s, struct bio *bio) 1423515ad66cSMikulas Patocka { 1424515ad66cSMikulas Patocka struct bio *n; 1425515ad66cSMikulas Patocka int r; 1426515ad66cSMikulas Patocka 1427515ad66cSMikulas Patocka while (bio) { 1428515ad66cSMikulas Patocka n = bio->bi_next; 1429515ad66cSMikulas Patocka bio->bi_next = NULL; 1430515ad66cSMikulas Patocka r = do_origin(s->origin, bio); 1431515ad66cSMikulas Patocka if (r == DM_MAPIO_REMAPPED) 1432515ad66cSMikulas Patocka generic_make_request(bio); 1433515ad66cSMikulas Patocka bio = n; 1434515ad66cSMikulas Patocka } 1435515ad66cSMikulas Patocka } 1436515ad66cSMikulas Patocka 14371da177e4SLinus Torvalds /* 14381da177e4SLinus Torvalds * Error a list of buffers. 14391da177e4SLinus Torvalds */ 14401da177e4SLinus Torvalds static void error_bios(struct bio *bio) 14411da177e4SLinus Torvalds { 14421da177e4SLinus Torvalds struct bio *n; 14431da177e4SLinus Torvalds 14441da177e4SLinus Torvalds while (bio) { 14451da177e4SLinus Torvalds n = bio->bi_next; 14461da177e4SLinus Torvalds bio->bi_next = NULL; 14476712ecf8SNeilBrown bio_io_error(bio); 14481da177e4SLinus Torvalds bio = n; 14491da177e4SLinus Torvalds } 14501da177e4SLinus Torvalds } 14511da177e4SLinus Torvalds 1452695368acSAlasdair G Kergon static void __invalidate_snapshot(struct dm_snapshot *s, int err) 145376df1c65SAlasdair G Kergon { 145476df1c65SAlasdair G Kergon if (!s->valid) 145576df1c65SAlasdair G Kergon return; 145676df1c65SAlasdair G Kergon 145776df1c65SAlasdair G Kergon if (err == -EIO) 145876df1c65SAlasdair G Kergon DMERR("Invalidating snapshot: Error reading/writing."); 145976df1c65SAlasdair G Kergon else if (err == -ENOMEM) 146076df1c65SAlasdair G Kergon DMERR("Invalidating snapshot: Unable to allocate exception."); 146176df1c65SAlasdair G Kergon 1462493df71cSJonathan Brassow if (s->store->type->drop_snapshot) 1463493df71cSJonathan Brassow s->store->type->drop_snapshot(s->store); 146476df1c65SAlasdair G Kergon 146576df1c65SAlasdair G Kergon s->valid = 0; 146676df1c65SAlasdair G Kergon 1467fc56f6fbSMike Snitzer dm_table_event(s->ti->table); 146876df1c65SAlasdair G Kergon } 146976df1c65SAlasdair G Kergon 1470385277bfSMikulas Patocka static void pending_complete(void *context, int success) 14711da177e4SLinus Torvalds { 1472385277bfSMikulas Patocka struct dm_snap_pending_exception *pe = context; 14731d4989c8SJon Brassow struct dm_exception *e; 14741da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 14759d493fa8SAlasdair G Kergon struct bio *origin_bios = NULL; 14769d493fa8SAlasdair G Kergon struct bio *snapshot_bios = NULL; 1477a6e50b40SMikulas Patocka struct bio *full_bio = NULL; 14789d493fa8SAlasdair G Kergon int error = 0; 14791da177e4SLinus Torvalds 148076df1c65SAlasdair G Kergon if (!success) { 148176df1c65SAlasdair G Kergon /* Read/write error - snapshot is unusable */ 1482ae1093beSMikulas Patocka mutex_lock(&s->lock); 1483695368acSAlasdair G Kergon __invalidate_snapshot(s, -EIO); 14849d493fa8SAlasdair G Kergon error = 1; 148576df1c65SAlasdair G Kergon goto out; 148676df1c65SAlasdair G Kergon } 148776df1c65SAlasdair G Kergon 1488119bc547SMikulas Patocka e = alloc_completed_exception(GFP_NOIO); 148976df1c65SAlasdair G Kergon if (!e) { 1490ae1093beSMikulas Patocka mutex_lock(&s->lock); 1491695368acSAlasdair G Kergon __invalidate_snapshot(s, -ENOMEM); 14929d493fa8SAlasdair G Kergon error = 1; 14931da177e4SLinus Torvalds goto out; 14941da177e4SLinus Torvalds } 14951da177e4SLinus Torvalds *e = pe->e; 14961da177e4SLinus Torvalds 1497ae1093beSMikulas Patocka mutex_lock(&s->lock); 14989d493fa8SAlasdair G Kergon if (!s->valid) { 14993510cb94SJon Brassow free_completed_exception(e); 15009d493fa8SAlasdair G Kergon error = 1; 15019d493fa8SAlasdair G Kergon goto out; 15029d493fa8SAlasdair G Kergon } 15039d493fa8SAlasdair G Kergon 1504a8d41b59SMikulas Patocka /* 150565fc7c37SNikos Tsironis * Add a proper exception. After inserting the completed exception all 150665fc7c37SNikos Tsironis * subsequent snapshot reads to this chunk will be redirected to the 150765fc7c37SNikos Tsironis * COW device. This ensures that we do not starve. Moreover, as long 150865fc7c37SNikos Tsironis * as the pending exception exists, neither origin writes nor snapshot 150965fc7c37SNikos Tsironis * merging can overwrite the chunk in origin. 15101da177e4SLinus Torvalds */ 15113510cb94SJon Brassow dm_insert_exception(&s->complete, e); 15121da177e4SLinus Torvalds 151365fc7c37SNikos Tsironis /* Wait for conflicting reads to drain */ 151465fc7c37SNikos Tsironis if (__chunk_is_tracked(s, pe->e.old_chunk)) { 151565fc7c37SNikos Tsironis mutex_unlock(&s->lock); 151665fc7c37SNikos Tsironis __check_for_conflicting_io(s, pe->e.old_chunk); 151765fc7c37SNikos Tsironis mutex_lock(&s->lock); 151865fc7c37SNikos Tsironis } 151965fc7c37SNikos Tsironis 15201da177e4SLinus Torvalds out: 152165fc7c37SNikos Tsironis /* Remove the in-flight exception from the list */ 15223510cb94SJon Brassow dm_remove_exception(&pe->e); 15239d493fa8SAlasdair G Kergon snapshot_bios = bio_list_get(&pe->snapshot_bios); 1524515ad66cSMikulas Patocka origin_bios = bio_list_get(&pe->origin_bios); 1525a6e50b40SMikulas Patocka full_bio = pe->full_bio; 1526fe3265b1SMikulas Patocka if (full_bio) 1527a6e50b40SMikulas Patocka full_bio->bi_end_io = pe->full_bio_end_io; 152873dfd078SMikulas Patocka increment_pending_exceptions_done_count(); 152973dfd078SMikulas Patocka 1530ae1093beSMikulas Patocka mutex_unlock(&s->lock); 15319d493fa8SAlasdair G Kergon 15329d493fa8SAlasdair G Kergon /* Submit any pending write bios */ 1533a6e50b40SMikulas Patocka if (error) { 1534a6e50b40SMikulas Patocka if (full_bio) 1535a6e50b40SMikulas Patocka bio_io_error(full_bio); 15369d493fa8SAlasdair G Kergon error_bios(snapshot_bios); 1537a6e50b40SMikulas Patocka } else { 1538a6e50b40SMikulas Patocka if (full_bio) 15394246a0b6SChristoph Hellwig bio_endio(full_bio); 15409d493fa8SAlasdair G Kergon flush_bios(snapshot_bios); 1541a6e50b40SMikulas Patocka } 15429d493fa8SAlasdair G Kergon 1543515ad66cSMikulas Patocka retry_origin_bios(s, origin_bios); 154422aa66a3SMikulas Patocka 154522aa66a3SMikulas Patocka free_pending_exception(pe); 15461da177e4SLinus Torvalds } 15471da177e4SLinus Torvalds 1548230c83afSMikulas Patocka static void complete_exception(struct dm_snap_pending_exception *pe) 1549230c83afSMikulas Patocka { 1550230c83afSMikulas Patocka struct dm_snapshot *s = pe->snap; 1551230c83afSMikulas Patocka 1552230c83afSMikulas Patocka /* Update the metadata if we are persistent */ 1553385277bfSMikulas Patocka s->store->type->commit_exception(s->store, &pe->e, !pe->copy_error, 1554385277bfSMikulas Patocka pending_complete, pe); 1555230c83afSMikulas Patocka } 1556230c83afSMikulas Patocka 15571da177e4SLinus Torvalds /* 15581da177e4SLinus Torvalds * Called when the copy I/O has finished. kcopyd actually runs 15591da177e4SLinus Torvalds * this code so don't block. 15601da177e4SLinus Torvalds */ 15614cdc1d1fSAlasdair G Kergon static void copy_callback(int read_err, unsigned long write_err, void *context) 15621da177e4SLinus Torvalds { 1563028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = context; 15641da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 15651da177e4SLinus Torvalds 1566230c83afSMikulas Patocka pe->copy_error = read_err || write_err; 15671da177e4SLinus Torvalds 1568230c83afSMikulas Patocka if (pe->exception_sequence == s->exception_complete_sequence) { 15693db2776dSDavid Jeffery struct rb_node *next; 15703db2776dSDavid Jeffery 1571230c83afSMikulas Patocka s->exception_complete_sequence++; 1572230c83afSMikulas Patocka complete_exception(pe); 1573230c83afSMikulas Patocka 15743db2776dSDavid Jeffery next = rb_first(&s->out_of_order_tree); 15753db2776dSDavid Jeffery while (next) { 15763db2776dSDavid Jeffery pe = rb_entry(next, struct dm_snap_pending_exception, 15773db2776dSDavid Jeffery out_of_order_node); 1578230c83afSMikulas Patocka if (pe->exception_sequence != s->exception_complete_sequence) 1579230c83afSMikulas Patocka break; 15803db2776dSDavid Jeffery next = rb_next(next); 1581230c83afSMikulas Patocka s->exception_complete_sequence++; 15823db2776dSDavid Jeffery rb_erase(&pe->out_of_order_node, &s->out_of_order_tree); 1583230c83afSMikulas Patocka complete_exception(pe); 15843db2776dSDavid Jeffery cond_resched(); 1585230c83afSMikulas Patocka } 1586230c83afSMikulas Patocka } else { 15873db2776dSDavid Jeffery struct rb_node *parent = NULL; 15883db2776dSDavid Jeffery struct rb_node **p = &s->out_of_order_tree.rb_node; 1589230c83afSMikulas Patocka struct dm_snap_pending_exception *pe2; 1590230c83afSMikulas Patocka 15913db2776dSDavid Jeffery while (*p) { 15923db2776dSDavid Jeffery pe2 = rb_entry(*p, struct dm_snap_pending_exception, out_of_order_node); 15933db2776dSDavid Jeffery parent = *p; 15943db2776dSDavid Jeffery 15953db2776dSDavid Jeffery BUG_ON(pe->exception_sequence == pe2->exception_sequence); 15963db2776dSDavid Jeffery if (pe->exception_sequence < pe2->exception_sequence) 15973db2776dSDavid Jeffery p = &((*p)->rb_left); 15983db2776dSDavid Jeffery else 15993db2776dSDavid Jeffery p = &((*p)->rb_right); 1600230c83afSMikulas Patocka } 16013db2776dSDavid Jeffery 16023db2776dSDavid Jeffery rb_link_node(&pe->out_of_order_node, parent, p); 16033db2776dSDavid Jeffery rb_insert_color(&pe->out_of_order_node, &s->out_of_order_tree); 1604230c83afSMikulas Patocka } 1605721b1d98SNikos Tsironis up(&s->cow_count); 16061da177e4SLinus Torvalds } 16071da177e4SLinus Torvalds 16081da177e4SLinus Torvalds /* 16091da177e4SLinus Torvalds * Dispatches the copy operation to kcopyd. 16101da177e4SLinus Torvalds */ 1611028867acSAlasdair G Kergon static void start_copy(struct dm_snap_pending_exception *pe) 16121da177e4SLinus Torvalds { 16131da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 161422a1ceb1SHeinz Mauelshagen struct dm_io_region src, dest; 16151da177e4SLinus Torvalds struct block_device *bdev = s->origin->bdev; 16161da177e4SLinus Torvalds sector_t dev_size; 16171da177e4SLinus Torvalds 16181da177e4SLinus Torvalds dev_size = get_dev_size(bdev); 16191da177e4SLinus Torvalds 16201da177e4SLinus Torvalds src.bdev = bdev; 162171fab00aSJonathan Brassow src.sector = chunk_to_sector(s->store, pe->e.old_chunk); 1622df96eee6SMikulas Patocka src.count = min((sector_t)s->store->chunk_size, dev_size - src.sector); 16231da177e4SLinus Torvalds 1624fc56f6fbSMike Snitzer dest.bdev = s->cow->bdev; 162571fab00aSJonathan Brassow dest.sector = chunk_to_sector(s->store, pe->e.new_chunk); 16261da177e4SLinus Torvalds dest.count = src.count; 16271da177e4SLinus Torvalds 16281da177e4SLinus Torvalds /* Hand over to kcopyd */ 1629721b1d98SNikos Tsironis down(&s->cow_count); 1630a2d2b034SJonathan Brassow dm_kcopyd_copy(s->kcopyd_client, &src, 1, &dest, 0, copy_callback, pe); 16311da177e4SLinus Torvalds } 16321da177e4SLinus Torvalds 16334246a0b6SChristoph Hellwig static void full_bio_end_io(struct bio *bio) 1634a6e50b40SMikulas Patocka { 1635a6e50b40SMikulas Patocka void *callback_data = bio->bi_private; 1636a6e50b40SMikulas Patocka 16374e4cbee9SChristoph Hellwig dm_kcopyd_do_callback(callback_data, 0, bio->bi_status ? 1 : 0); 1638a6e50b40SMikulas Patocka } 1639a6e50b40SMikulas Patocka 1640a6e50b40SMikulas Patocka static void start_full_bio(struct dm_snap_pending_exception *pe, 1641a6e50b40SMikulas Patocka struct bio *bio) 1642a6e50b40SMikulas Patocka { 1643a6e50b40SMikulas Patocka struct dm_snapshot *s = pe->snap; 1644a6e50b40SMikulas Patocka void *callback_data; 1645a6e50b40SMikulas Patocka 1646a6e50b40SMikulas Patocka pe->full_bio = bio; 1647a6e50b40SMikulas Patocka pe->full_bio_end_io = bio->bi_end_io; 1648a6e50b40SMikulas Patocka 1649721b1d98SNikos Tsironis down(&s->cow_count); 1650a6e50b40SMikulas Patocka callback_data = dm_kcopyd_prepare_callback(s->kcopyd_client, 1651a6e50b40SMikulas Patocka copy_callback, pe); 1652a6e50b40SMikulas Patocka 1653a6e50b40SMikulas Patocka bio->bi_end_io = full_bio_end_io; 1654a6e50b40SMikulas Patocka bio->bi_private = callback_data; 1655a6e50b40SMikulas Patocka 1656a6e50b40SMikulas Patocka generic_make_request(bio); 1657a6e50b40SMikulas Patocka } 1658a6e50b40SMikulas Patocka 16592913808eSMikulas Patocka static struct dm_snap_pending_exception * 16602913808eSMikulas Patocka __lookup_pending_exception(struct dm_snapshot *s, chunk_t chunk) 16612913808eSMikulas Patocka { 16623510cb94SJon Brassow struct dm_exception *e = dm_lookup_exception(&s->pending, chunk); 16632913808eSMikulas Patocka 16642913808eSMikulas Patocka if (!e) 16652913808eSMikulas Patocka return NULL; 16662913808eSMikulas Patocka 16672913808eSMikulas Patocka return container_of(e, struct dm_snap_pending_exception, e); 16682913808eSMikulas Patocka } 16692913808eSMikulas Patocka 16701da177e4SLinus Torvalds /* 167165fc7c37SNikos Tsironis * Inserts a pending exception into the pending table. 167265fc7c37SNikos Tsironis * 167365fc7c37SNikos Tsironis * NOTE: a write lock must be held on snap->lock before calling 167465fc7c37SNikos Tsironis * this. 167565fc7c37SNikos Tsironis */ 167665fc7c37SNikos Tsironis static struct dm_snap_pending_exception * 167765fc7c37SNikos Tsironis __insert_pending_exception(struct dm_snapshot *s, 167865fc7c37SNikos Tsironis struct dm_snap_pending_exception *pe, chunk_t chunk) 167965fc7c37SNikos Tsironis { 168065fc7c37SNikos Tsironis pe->e.old_chunk = chunk; 168165fc7c37SNikos Tsironis bio_list_init(&pe->origin_bios); 168265fc7c37SNikos Tsironis bio_list_init(&pe->snapshot_bios); 168365fc7c37SNikos Tsironis pe->started = 0; 168465fc7c37SNikos Tsironis pe->full_bio = NULL; 168565fc7c37SNikos Tsironis 168665fc7c37SNikos Tsironis if (s->store->type->prepare_exception(s->store, &pe->e)) { 168765fc7c37SNikos Tsironis free_pending_exception(pe); 168865fc7c37SNikos Tsironis return NULL; 168965fc7c37SNikos Tsironis } 169065fc7c37SNikos Tsironis 169165fc7c37SNikos Tsironis pe->exception_sequence = s->exception_start_sequence++; 169265fc7c37SNikos Tsironis 169365fc7c37SNikos Tsironis dm_insert_exception(&s->pending, &pe->e); 169465fc7c37SNikos Tsironis 169565fc7c37SNikos Tsironis return pe; 169665fc7c37SNikos Tsironis } 169765fc7c37SNikos Tsironis 169865fc7c37SNikos Tsironis /* 16991da177e4SLinus Torvalds * Looks to see if this snapshot already has a pending exception 17001da177e4SLinus Torvalds * for this chunk, otherwise it allocates a new one and inserts 17011da177e4SLinus Torvalds * it into the pending table. 17021da177e4SLinus Torvalds * 17031da177e4SLinus Torvalds * NOTE: a write lock must be held on snap->lock before calling 17041da177e4SLinus Torvalds * this. 17051da177e4SLinus Torvalds */ 1706028867acSAlasdair G Kergon static struct dm_snap_pending_exception * 1707c6621392SMikulas Patocka __find_pending_exception(struct dm_snapshot *s, 1708c6621392SMikulas Patocka struct dm_snap_pending_exception *pe, chunk_t chunk) 17091da177e4SLinus Torvalds { 1710c6621392SMikulas Patocka struct dm_snap_pending_exception *pe2; 171176df1c65SAlasdair G Kergon 17122913808eSMikulas Patocka pe2 = __lookup_pending_exception(s, chunk); 17132913808eSMikulas Patocka if (pe2) { 17141da177e4SLinus Torvalds free_pending_exception(pe); 17152913808eSMikulas Patocka return pe2; 171676df1c65SAlasdair G Kergon } 171776df1c65SAlasdair G Kergon 171865fc7c37SNikos Tsironis return __insert_pending_exception(s, pe, chunk); 17191da177e4SLinus Torvalds } 17201da177e4SLinus Torvalds 17211d4989c8SJon Brassow static void remap_exception(struct dm_snapshot *s, struct dm_exception *e, 1722d74f81f8SMilan Broz struct bio *bio, chunk_t chunk) 17231da177e4SLinus Torvalds { 172474d46992SChristoph Hellwig bio_set_dev(bio, s->cow->bdev); 17254f024f37SKent Overstreet bio->bi_iter.bi_sector = 17264f024f37SKent Overstreet chunk_to_sector(s->store, dm_chunk_number(e->new_chunk) + 1727d74f81f8SMilan Broz (chunk - e->old_chunk)) + 17284f024f37SKent Overstreet (bio->bi_iter.bi_sector & s->store->chunk_mask); 17291da177e4SLinus Torvalds } 17301da177e4SLinus Torvalds 17317de3ee57SMikulas Patocka static int snapshot_map(struct dm_target *ti, struct bio *bio) 17321da177e4SLinus Torvalds { 17331d4989c8SJon Brassow struct dm_exception *e; 1734028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 1735d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED; 17361da177e4SLinus Torvalds chunk_t chunk; 1737028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = NULL; 17381da177e4SLinus Torvalds 1739ee18026aSMikulas Patocka init_tracked_chunk(bio); 1740ee18026aSMikulas Patocka 17411eff9d32SJens Axboe if (bio->bi_opf & REQ_PREFLUSH) { 174274d46992SChristoph Hellwig bio_set_dev(bio, s->cow->bdev); 1743494b3ee7SMikulas Patocka return DM_MAPIO_REMAPPED; 1744494b3ee7SMikulas Patocka } 1745494b3ee7SMikulas Patocka 17464f024f37SKent Overstreet chunk = sector_to_chunk(s->store, bio->bi_iter.bi_sector); 17471da177e4SLinus Torvalds 17481da177e4SLinus Torvalds /* Full snapshots are not usable */ 174976df1c65SAlasdair G Kergon /* To get here the table must be live so s->active is always set. */ 17501da177e4SLinus Torvalds if (!s->valid) 1751846785e6SChristoph Hellwig return DM_MAPIO_KILL; 17521da177e4SLinus Torvalds 1753ae1093beSMikulas Patocka mutex_lock(&s->lock); 17541da177e4SLinus Torvalds 175570246286SChristoph Hellwig if (!s->valid || (unlikely(s->snapshot_overflowed) && 175670246286SChristoph Hellwig bio_data_dir(bio) == WRITE)) { 1757846785e6SChristoph Hellwig r = DM_MAPIO_KILL; 175876df1c65SAlasdair G Kergon goto out_unlock; 175976df1c65SAlasdair G Kergon } 176076df1c65SAlasdair G Kergon 17611da177e4SLinus Torvalds /* If the block is already remapped - use that, else remap it */ 17623510cb94SJon Brassow e = dm_lookup_exception(&s->complete, chunk); 17631da177e4SLinus Torvalds if (e) { 1764d74f81f8SMilan Broz remap_exception(s, e, bio, chunk); 176576df1c65SAlasdair G Kergon goto out_unlock; 176676df1c65SAlasdair G Kergon } 17671da177e4SLinus Torvalds 1768ba40a2aaSAlasdair G Kergon /* 1769ba40a2aaSAlasdair G Kergon * Write to snapshot - higher level takes care of RW/RO 1770ba40a2aaSAlasdair G Kergon * flags so we should only get this if we are 1771ba40a2aaSAlasdair G Kergon * writeable. 1772ba40a2aaSAlasdair G Kergon */ 177370246286SChristoph Hellwig if (bio_data_dir(bio) == WRITE) { 17742913808eSMikulas Patocka pe = __lookup_pending_exception(s, chunk); 17752913808eSMikulas Patocka if (!pe) { 1776ae1093beSMikulas Patocka mutex_unlock(&s->lock); 1777c6621392SMikulas Patocka pe = alloc_pending_exception(s); 1778ae1093beSMikulas Patocka mutex_lock(&s->lock); 1779c6621392SMikulas Patocka 178076c44f6dSMikulas Patocka if (!s->valid || s->snapshot_overflowed) { 1781c6621392SMikulas Patocka free_pending_exception(pe); 1782846785e6SChristoph Hellwig r = DM_MAPIO_KILL; 1783c6621392SMikulas Patocka goto out_unlock; 1784c6621392SMikulas Patocka } 1785c6621392SMikulas Patocka 17863510cb94SJon Brassow e = dm_lookup_exception(&s->complete, chunk); 178735bf659bSMikulas Patocka if (e) { 178835bf659bSMikulas Patocka free_pending_exception(pe); 178935bf659bSMikulas Patocka remap_exception(s, e, bio, chunk); 179035bf659bSMikulas Patocka goto out_unlock; 179135bf659bSMikulas Patocka } 179235bf659bSMikulas Patocka 1793c6621392SMikulas Patocka pe = __find_pending_exception(s, pe, chunk); 17941da177e4SLinus Torvalds if (!pe) { 1795b0d3cc01SMike Snitzer if (s->store->userspace_supports_overflow) { 179676c44f6dSMikulas Patocka s->snapshot_overflowed = 1; 179776c44f6dSMikulas Patocka DMERR("Snapshot overflowed: Unable to allocate exception."); 1798b0d3cc01SMike Snitzer } else 1799b0d3cc01SMike Snitzer __invalidate_snapshot(s, -ENOMEM); 1800846785e6SChristoph Hellwig r = DM_MAPIO_KILL; 180176df1c65SAlasdair G Kergon goto out_unlock; 180276df1c65SAlasdair G Kergon } 18032913808eSMikulas Patocka } 180476df1c65SAlasdair G Kergon 1805d74f81f8SMilan Broz remap_exception(s, &pe->e, bio, chunk); 18061da177e4SLinus Torvalds 1807d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 1808ba40a2aaSAlasdair G Kergon 1809a6e50b40SMikulas Patocka if (!pe->started && 18104f024f37SKent Overstreet bio->bi_iter.bi_size == 18114f024f37SKent Overstreet (s->store->chunk_size << SECTOR_SHIFT)) { 1812a6e50b40SMikulas Patocka pe->started = 1; 1813ae1093beSMikulas Patocka mutex_unlock(&s->lock); 1814a6e50b40SMikulas Patocka start_full_bio(pe, bio); 1815a6e50b40SMikulas Patocka goto out; 1816a6e50b40SMikulas Patocka } 1817a6e50b40SMikulas Patocka 1818a6e50b40SMikulas Patocka bio_list_add(&pe->snapshot_bios, bio); 1819a6e50b40SMikulas Patocka 18201da177e4SLinus Torvalds if (!pe->started) { 18211da177e4SLinus Torvalds /* this is protected by snap->lock */ 18221da177e4SLinus Torvalds pe->started = 1; 1823ae1093beSMikulas Patocka mutex_unlock(&s->lock); 182476df1c65SAlasdair G Kergon start_copy(pe); 1825ba40a2aaSAlasdair G Kergon goto out; 1826ba40a2aaSAlasdair G Kergon } 1827cd45daffSMikulas Patocka } else { 182874d46992SChristoph Hellwig bio_set_dev(bio, s->origin->bdev); 1829ee18026aSMikulas Patocka track_chunk(s, bio, chunk); 1830cd45daffSMikulas Patocka } 18311da177e4SLinus Torvalds 1832ba40a2aaSAlasdair G Kergon out_unlock: 1833ae1093beSMikulas Patocka mutex_unlock(&s->lock); 1834ba40a2aaSAlasdair G Kergon out: 18351da177e4SLinus Torvalds return r; 18361da177e4SLinus Torvalds } 18371da177e4SLinus Torvalds 18383452c2a1SMikulas Patocka /* 18393452c2a1SMikulas Patocka * A snapshot-merge target behaves like a combination of a snapshot 18403452c2a1SMikulas Patocka * target and a snapshot-origin target. It only generates new 18413452c2a1SMikulas Patocka * exceptions in other snapshots and not in the one that is being 18423452c2a1SMikulas Patocka * merged. 18433452c2a1SMikulas Patocka * 18443452c2a1SMikulas Patocka * For each chunk, if there is an existing exception, it is used to 18453452c2a1SMikulas Patocka * redirect I/O to the cow device. Otherwise I/O is sent to the origin, 18463452c2a1SMikulas Patocka * which in turn might generate exceptions in other snapshots. 18479fe86254SMikulas Patocka * If merging is currently taking place on the chunk in question, the 18489fe86254SMikulas Patocka * I/O is deferred by adding it to s->bios_queued_during_merge. 18493452c2a1SMikulas Patocka */ 18507de3ee57SMikulas Patocka static int snapshot_merge_map(struct dm_target *ti, struct bio *bio) 18513452c2a1SMikulas Patocka { 18523452c2a1SMikulas Patocka struct dm_exception *e; 18533452c2a1SMikulas Patocka struct dm_snapshot *s = ti->private; 18543452c2a1SMikulas Patocka int r = DM_MAPIO_REMAPPED; 18553452c2a1SMikulas Patocka chunk_t chunk; 18563452c2a1SMikulas Patocka 1857ee18026aSMikulas Patocka init_tracked_chunk(bio); 1858ee18026aSMikulas Patocka 18591eff9d32SJens Axboe if (bio->bi_opf & REQ_PREFLUSH) { 186055a62eefSAlasdair G Kergon if (!dm_bio_get_target_bio_nr(bio)) 186174d46992SChristoph Hellwig bio_set_dev(bio, s->origin->bdev); 186210b8106aSMike Snitzer else 186374d46992SChristoph Hellwig bio_set_dev(bio, s->cow->bdev); 186410b8106aSMike Snitzer return DM_MAPIO_REMAPPED; 186510b8106aSMike Snitzer } 186610b8106aSMike Snitzer 18674f024f37SKent Overstreet chunk = sector_to_chunk(s->store, bio->bi_iter.bi_sector); 18683452c2a1SMikulas Patocka 1869ae1093beSMikulas Patocka mutex_lock(&s->lock); 18703452c2a1SMikulas Patocka 1871d2fdb776SMikulas Patocka /* Full merging snapshots are redirected to the origin */ 1872d2fdb776SMikulas Patocka if (!s->valid) 1873d2fdb776SMikulas Patocka goto redirect_to_origin; 18743452c2a1SMikulas Patocka 18753452c2a1SMikulas Patocka /* If the block is already remapped - use that */ 18763452c2a1SMikulas Patocka e = dm_lookup_exception(&s->complete, chunk); 18773452c2a1SMikulas Patocka if (e) { 18789fe86254SMikulas Patocka /* Queue writes overlapping with chunks being merged */ 187970246286SChristoph Hellwig if (bio_data_dir(bio) == WRITE && 18809fe86254SMikulas Patocka chunk >= s->first_merging_chunk && 18819fe86254SMikulas Patocka chunk < (s->first_merging_chunk + 18829fe86254SMikulas Patocka s->num_merging_chunks)) { 188374d46992SChristoph Hellwig bio_set_dev(bio, s->origin->bdev); 18849fe86254SMikulas Patocka bio_list_add(&s->bios_queued_during_merge, bio); 18859fe86254SMikulas Patocka r = DM_MAPIO_SUBMITTED; 18869fe86254SMikulas Patocka goto out_unlock; 18879fe86254SMikulas Patocka } 188817aa0332SMikulas Patocka 18893452c2a1SMikulas Patocka remap_exception(s, e, bio, chunk); 189017aa0332SMikulas Patocka 189170246286SChristoph Hellwig if (bio_data_dir(bio) == WRITE) 1892ee18026aSMikulas Patocka track_chunk(s, bio, chunk); 18933452c2a1SMikulas Patocka goto out_unlock; 18943452c2a1SMikulas Patocka } 18953452c2a1SMikulas Patocka 1896d2fdb776SMikulas Patocka redirect_to_origin: 189774d46992SChristoph Hellwig bio_set_dev(bio, s->origin->bdev); 18983452c2a1SMikulas Patocka 189970246286SChristoph Hellwig if (bio_data_dir(bio) == WRITE) { 1900ae1093beSMikulas Patocka mutex_unlock(&s->lock); 19013452c2a1SMikulas Patocka return do_origin(s->origin, bio); 19023452c2a1SMikulas Patocka } 19033452c2a1SMikulas Patocka 19043452c2a1SMikulas Patocka out_unlock: 1905ae1093beSMikulas Patocka mutex_unlock(&s->lock); 19063452c2a1SMikulas Patocka 19073452c2a1SMikulas Patocka return r; 19083452c2a1SMikulas Patocka } 19093452c2a1SMikulas Patocka 19104e4cbee9SChristoph Hellwig static int snapshot_end_io(struct dm_target *ti, struct bio *bio, 19114e4cbee9SChristoph Hellwig blk_status_t *error) 1912cd45daffSMikulas Patocka { 1913cd45daffSMikulas Patocka struct dm_snapshot *s = ti->private; 1914cd45daffSMikulas Patocka 1915ee18026aSMikulas Patocka if (is_bio_tracked(bio)) 1916ee18026aSMikulas Patocka stop_tracking_chunk(s, bio); 1917cd45daffSMikulas Patocka 19181be56909SChristoph Hellwig return DM_ENDIO_DONE; 1919cd45daffSMikulas Patocka } 1920cd45daffSMikulas Patocka 19211e03f97eSMikulas Patocka static void snapshot_merge_presuspend(struct dm_target *ti) 19221e03f97eSMikulas Patocka { 19231e03f97eSMikulas Patocka struct dm_snapshot *s = ti->private; 19241e03f97eSMikulas Patocka 19251e03f97eSMikulas Patocka stop_merge(s); 19261e03f97eSMikulas Patocka } 19271e03f97eSMikulas Patocka 1928c1f0c183SMike Snitzer static int snapshot_preresume(struct dm_target *ti) 1929c1f0c183SMike Snitzer { 1930c1f0c183SMike Snitzer int r = 0; 1931c1f0c183SMike Snitzer struct dm_snapshot *s = ti->private; 1932c1f0c183SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 1933c1f0c183SMike Snitzer 1934c1f0c183SMike Snitzer down_read(&_origins_lock); 19359d3b15c4SMikulas Patocka (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); 1936c1f0c183SMike Snitzer if (snap_src && snap_dest) { 1937ae1093beSMikulas Patocka mutex_lock(&snap_src->lock); 1938c1f0c183SMike Snitzer if (s == snap_src) { 1939c1f0c183SMike Snitzer DMERR("Unable to resume snapshot source until " 1940c1f0c183SMike Snitzer "handover completes."); 1941c1f0c183SMike Snitzer r = -EINVAL; 1942b83b2f29SMike Snitzer } else if (!dm_suspended(snap_src->ti)) { 1943c1f0c183SMike Snitzer DMERR("Unable to perform snapshot handover until " 1944c1f0c183SMike Snitzer "source is suspended."); 1945c1f0c183SMike Snitzer r = -EINVAL; 1946c1f0c183SMike Snitzer } 1947ae1093beSMikulas Patocka mutex_unlock(&snap_src->lock); 1948c1f0c183SMike Snitzer } 1949c1f0c183SMike Snitzer up_read(&_origins_lock); 1950c1f0c183SMike Snitzer 1951c1f0c183SMike Snitzer return r; 1952c1f0c183SMike Snitzer } 1953c1f0c183SMike Snitzer 19541da177e4SLinus Torvalds static void snapshot_resume(struct dm_target *ti) 19551da177e4SLinus Torvalds { 1956028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 195709ee96b2SMikulas Patocka struct dm_snapshot *snap_src = NULL, *snap_dest = NULL, *snap_merging = NULL; 1958b735fedeSMikulas Patocka struct dm_origin *o; 1959b735fedeSMikulas Patocka struct mapped_device *origin_md = NULL; 196009ee96b2SMikulas Patocka bool must_restart_merging = false; 1961c1f0c183SMike Snitzer 1962c1f0c183SMike Snitzer down_read(&_origins_lock); 1963b735fedeSMikulas Patocka 1964b735fedeSMikulas Patocka o = __lookup_dm_origin(s->origin->bdev); 1965b735fedeSMikulas Patocka if (o) 1966b735fedeSMikulas Patocka origin_md = dm_table_get_md(o->ti->table); 196709ee96b2SMikulas Patocka if (!origin_md) { 196809ee96b2SMikulas Patocka (void) __find_snapshots_sharing_cow(s, NULL, NULL, &snap_merging); 196909ee96b2SMikulas Patocka if (snap_merging) 197009ee96b2SMikulas Patocka origin_md = dm_table_get_md(snap_merging->ti->table); 197109ee96b2SMikulas Patocka } 1972b735fedeSMikulas Patocka if (origin_md == dm_table_get_md(ti->table)) 1973b735fedeSMikulas Patocka origin_md = NULL; 197409ee96b2SMikulas Patocka if (origin_md) { 197509ee96b2SMikulas Patocka if (dm_hold(origin_md)) 197609ee96b2SMikulas Patocka origin_md = NULL; 197709ee96b2SMikulas Patocka } 1978b735fedeSMikulas Patocka 197909ee96b2SMikulas Patocka up_read(&_origins_lock); 198009ee96b2SMikulas Patocka 198109ee96b2SMikulas Patocka if (origin_md) { 1982b735fedeSMikulas Patocka dm_internal_suspend_fast(origin_md); 198309ee96b2SMikulas Patocka if (snap_merging && test_bit(RUNNING_MERGE, &snap_merging->state_bits)) { 198409ee96b2SMikulas Patocka must_restart_merging = true; 198509ee96b2SMikulas Patocka stop_merge(snap_merging); 198609ee96b2SMikulas Patocka } 198709ee96b2SMikulas Patocka } 198809ee96b2SMikulas Patocka 198909ee96b2SMikulas Patocka down_read(&_origins_lock); 1990b735fedeSMikulas Patocka 19919d3b15c4SMikulas Patocka (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); 1992c1f0c183SMike Snitzer if (snap_src && snap_dest) { 1993ae1093beSMikulas Patocka mutex_lock(&snap_src->lock); 1994ae1093beSMikulas Patocka mutex_lock_nested(&snap_dest->lock, SINGLE_DEPTH_NESTING); 1995c1f0c183SMike Snitzer __handover_exceptions(snap_src, snap_dest); 1996ae1093beSMikulas Patocka mutex_unlock(&snap_dest->lock); 1997ae1093beSMikulas Patocka mutex_unlock(&snap_src->lock); 1998c1f0c183SMike Snitzer } 1999b735fedeSMikulas Patocka 2000c1f0c183SMike Snitzer up_read(&_origins_lock); 2001c1f0c183SMike Snitzer 200209ee96b2SMikulas Patocka if (origin_md) { 200309ee96b2SMikulas Patocka if (must_restart_merging) 200409ee96b2SMikulas Patocka start_merge(snap_merging); 200509ee96b2SMikulas Patocka dm_internal_resume_fast(origin_md); 200609ee96b2SMikulas Patocka dm_put(origin_md); 200709ee96b2SMikulas Patocka } 200809ee96b2SMikulas Patocka 2009c1f0c183SMike Snitzer /* Now we have correct chunk size, reregister */ 2010c1f0c183SMike Snitzer reregister_snapshot(s); 20111da177e4SLinus Torvalds 2012ae1093beSMikulas Patocka mutex_lock(&s->lock); 2013aa14edebSAlasdair G Kergon s->active = 1; 2014ae1093beSMikulas Patocka mutex_unlock(&s->lock); 20151da177e4SLinus Torvalds } 20161da177e4SLinus Torvalds 2017542f9038SMike Snitzer static uint32_t get_origin_minimum_chunksize(struct block_device *bdev) 20181e03f97eSMikulas Patocka { 2019542f9038SMike Snitzer uint32_t min_chunksize; 20201e03f97eSMikulas Patocka 20211e03f97eSMikulas Patocka down_read(&_origins_lock); 20221e03f97eSMikulas Patocka min_chunksize = __minimum_chunk_size(__lookup_origin(bdev)); 20231e03f97eSMikulas Patocka up_read(&_origins_lock); 20241e03f97eSMikulas Patocka 20251e03f97eSMikulas Patocka return min_chunksize; 20261e03f97eSMikulas Patocka } 20271e03f97eSMikulas Patocka 20281e03f97eSMikulas Patocka static void snapshot_merge_resume(struct dm_target *ti) 20291e03f97eSMikulas Patocka { 20301e03f97eSMikulas Patocka struct dm_snapshot *s = ti->private; 20311e03f97eSMikulas Patocka 20321e03f97eSMikulas Patocka /* 20331e03f97eSMikulas Patocka * Handover exceptions from existing snapshot. 20341e03f97eSMikulas Patocka */ 20351e03f97eSMikulas Patocka snapshot_resume(ti); 20361e03f97eSMikulas Patocka 20371e03f97eSMikulas Patocka /* 2038542f9038SMike Snitzer * snapshot-merge acts as an origin, so set ti->max_io_len 20391e03f97eSMikulas Patocka */ 2040542f9038SMike Snitzer ti->max_io_len = get_origin_minimum_chunksize(s->origin->bdev); 20411e03f97eSMikulas Patocka 20421e03f97eSMikulas Patocka start_merge(s); 20431e03f97eSMikulas Patocka } 20441e03f97eSMikulas Patocka 2045fd7c092eSMikulas Patocka static void snapshot_status(struct dm_target *ti, status_type_t type, 20461f4e0ff0SAlasdair G Kergon unsigned status_flags, char *result, unsigned maxlen) 20471da177e4SLinus Torvalds { 20482e4a31dfSJonathan Brassow unsigned sz = 0; 2049028867acSAlasdair G Kergon struct dm_snapshot *snap = ti->private; 20501da177e4SLinus Torvalds 20511da177e4SLinus Torvalds switch (type) { 20521da177e4SLinus Torvalds case STATUSTYPE_INFO: 205394e76572SMikulas Patocka 2054ae1093beSMikulas Patocka mutex_lock(&snap->lock); 205594e76572SMikulas Patocka 20561da177e4SLinus Torvalds if (!snap->valid) 20572e4a31dfSJonathan Brassow DMEMIT("Invalid"); 2058d8ddb1cfSMike Snitzer else if (snap->merge_failed) 2059d8ddb1cfSMike Snitzer DMEMIT("Merge failed"); 206076c44f6dSMikulas Patocka else if (snap->snapshot_overflowed) 206176c44f6dSMikulas Patocka DMEMIT("Overflow"); 20621da177e4SLinus Torvalds else { 2063985903bbSMike Snitzer if (snap->store->type->usage) { 2064985903bbSMike Snitzer sector_t total_sectors, sectors_allocated, 2065985903bbSMike Snitzer metadata_sectors; 2066985903bbSMike Snitzer snap->store->type->usage(snap->store, 2067985903bbSMike Snitzer &total_sectors, 2068985903bbSMike Snitzer §ors_allocated, 2069985903bbSMike Snitzer &metadata_sectors); 2070985903bbSMike Snitzer DMEMIT("%llu/%llu %llu", 2071985903bbSMike Snitzer (unsigned long long)sectors_allocated, 2072985903bbSMike Snitzer (unsigned long long)total_sectors, 2073985903bbSMike Snitzer (unsigned long long)metadata_sectors); 20741da177e4SLinus Torvalds } 20751da177e4SLinus Torvalds else 20762e4a31dfSJonathan Brassow DMEMIT("Unknown"); 20771da177e4SLinus Torvalds } 207894e76572SMikulas Patocka 2079ae1093beSMikulas Patocka mutex_unlock(&snap->lock); 208094e76572SMikulas Patocka 20811da177e4SLinus Torvalds break; 20821da177e4SLinus Torvalds 20831da177e4SLinus Torvalds case STATUSTYPE_TABLE: 20841da177e4SLinus Torvalds /* 20851da177e4SLinus Torvalds * kdevname returns a static pointer so we need 20861da177e4SLinus Torvalds * to make private copies if the output is to 20871da177e4SLinus Torvalds * make sense. 20881da177e4SLinus Torvalds */ 2089fc56f6fbSMike Snitzer DMEMIT("%s %s", snap->origin->name, snap->cow->name); 20901e302a92SJonathan Brassow snap->store->type->status(snap->store, type, result + sz, 20911e302a92SJonathan Brassow maxlen - sz); 20921da177e4SLinus Torvalds break; 20931da177e4SLinus Torvalds } 20941da177e4SLinus Torvalds } 20951da177e4SLinus Torvalds 20968811f46cSMike Snitzer static int snapshot_iterate_devices(struct dm_target *ti, 20978811f46cSMike Snitzer iterate_devices_callout_fn fn, void *data) 20988811f46cSMike Snitzer { 20998811f46cSMike Snitzer struct dm_snapshot *snap = ti->private; 21001e5554c8SMikulas Patocka int r; 21018811f46cSMike Snitzer 21021e5554c8SMikulas Patocka r = fn(ti, snap->origin, 0, ti->len, data); 21031e5554c8SMikulas Patocka 21041e5554c8SMikulas Patocka if (!r) 21051e5554c8SMikulas Patocka r = fn(ti, snap->cow, 0, get_dev_size(snap->cow->bdev), data); 21061e5554c8SMikulas Patocka 21071e5554c8SMikulas Patocka return r; 21088811f46cSMike Snitzer } 21098811f46cSMike Snitzer 21108811f46cSMike Snitzer 21111da177e4SLinus Torvalds /*----------------------------------------------------------------- 21121da177e4SLinus Torvalds * Origin methods 21131da177e4SLinus Torvalds *---------------------------------------------------------------*/ 21149eaae8ffSMikulas Patocka 21159eaae8ffSMikulas Patocka /* 21169eaae8ffSMikulas Patocka * If no exceptions need creating, DM_MAPIO_REMAPPED is returned and any 21179eaae8ffSMikulas Patocka * supplied bio was ignored. The caller may submit it immediately. 21189eaae8ffSMikulas Patocka * (No remapping actually occurs as the origin is always a direct linear 21199eaae8ffSMikulas Patocka * map.) 21209eaae8ffSMikulas Patocka * 21219eaae8ffSMikulas Patocka * If further exceptions are required, DM_MAPIO_SUBMITTED is returned 21229eaae8ffSMikulas Patocka * and any supplied bio is added to a list to be submitted once all 21239eaae8ffSMikulas Patocka * the necessary exceptions exist. 21249eaae8ffSMikulas Patocka */ 21259eaae8ffSMikulas Patocka static int __origin_write(struct list_head *snapshots, sector_t sector, 21269eaae8ffSMikulas Patocka struct bio *bio) 21271da177e4SLinus Torvalds { 2128515ad66cSMikulas Patocka int r = DM_MAPIO_REMAPPED; 21291da177e4SLinus Torvalds struct dm_snapshot *snap; 21301d4989c8SJon Brassow struct dm_exception *e; 213165fc7c37SNikos Tsironis struct dm_snap_pending_exception *pe, *pe2; 2132515ad66cSMikulas Patocka struct dm_snap_pending_exception *pe_to_start_now = NULL; 2133515ad66cSMikulas Patocka struct dm_snap_pending_exception *pe_to_start_last = NULL; 21341da177e4SLinus Torvalds chunk_t chunk; 21351da177e4SLinus Torvalds 21361da177e4SLinus Torvalds /* Do all the snapshots on this origin */ 21371da177e4SLinus Torvalds list_for_each_entry (snap, snapshots, list) { 21383452c2a1SMikulas Patocka /* 21393452c2a1SMikulas Patocka * Don't make new exceptions in a merging snapshot 21403452c2a1SMikulas Patocka * because it has effectively been deleted 21413452c2a1SMikulas Patocka */ 21423452c2a1SMikulas Patocka if (dm_target_is_snapshot_merge(snap->ti)) 21433452c2a1SMikulas Patocka continue; 21443452c2a1SMikulas Patocka 2145ae1093beSMikulas Patocka mutex_lock(&snap->lock); 214676df1c65SAlasdair G Kergon 2147aa14edebSAlasdair G Kergon /* Only deal with valid and active snapshots */ 2148aa14edebSAlasdair G Kergon if (!snap->valid || !snap->active) 214976df1c65SAlasdair G Kergon goto next_snapshot; 21501da177e4SLinus Torvalds 2151d5e404c1SAlasdair G Kergon /* Nothing to do if writing beyond end of snapshot */ 21529eaae8ffSMikulas Patocka if (sector >= dm_table_get_size(snap->ti->table)) 215376df1c65SAlasdair G Kergon goto next_snapshot; 21541da177e4SLinus Torvalds 21551da177e4SLinus Torvalds /* 21561da177e4SLinus Torvalds * Remember, different snapshots can have 21571da177e4SLinus Torvalds * different chunk sizes. 21581da177e4SLinus Torvalds */ 21599eaae8ffSMikulas Patocka chunk = sector_to_chunk(snap->store, sector); 21601da177e4SLinus Torvalds 216165fc7c37SNikos Tsironis pe = __lookup_pending_exception(snap, chunk); 216265fc7c37SNikos Tsironis if (!pe) { 21631da177e4SLinus Torvalds /* 216465fc7c37SNikos Tsironis * Check exception table to see if block is already 216565fc7c37SNikos Tsironis * remapped in this snapshot and trigger an exception 216665fc7c37SNikos Tsironis * if not. 21671da177e4SLinus Torvalds */ 21683510cb94SJon Brassow e = dm_lookup_exception(&snap->complete, chunk); 216976df1c65SAlasdair G Kergon if (e) 217076df1c65SAlasdair G Kergon goto next_snapshot; 217176df1c65SAlasdair G Kergon 2172ae1093beSMikulas Patocka mutex_unlock(&snap->lock); 2173c6621392SMikulas Patocka pe = alloc_pending_exception(snap); 2174ae1093beSMikulas Patocka mutex_lock(&snap->lock); 2175c6621392SMikulas Patocka 2176c6621392SMikulas Patocka if (!snap->valid) { 2177c6621392SMikulas Patocka free_pending_exception(pe); 2178c6621392SMikulas Patocka goto next_snapshot; 2179c6621392SMikulas Patocka } 2180c6621392SMikulas Patocka 218165fc7c37SNikos Tsironis pe2 = __lookup_pending_exception(snap, chunk); 218265fc7c37SNikos Tsironis 218365fc7c37SNikos Tsironis if (!pe2) { 21843510cb94SJon Brassow e = dm_lookup_exception(&snap->complete, chunk); 218535bf659bSMikulas Patocka if (e) { 218635bf659bSMikulas Patocka free_pending_exception(pe); 218735bf659bSMikulas Patocka goto next_snapshot; 218835bf659bSMikulas Patocka } 218935bf659bSMikulas Patocka 219065fc7c37SNikos Tsironis pe = __insert_pending_exception(snap, pe, chunk); 21911da177e4SLinus Torvalds if (!pe) { 2192695368acSAlasdair G Kergon __invalidate_snapshot(snap, -ENOMEM); 219376df1c65SAlasdair G Kergon goto next_snapshot; 219476df1c65SAlasdair G Kergon } 219565fc7c37SNikos Tsironis } else { 219665fc7c37SNikos Tsironis free_pending_exception(pe); 219765fc7c37SNikos Tsironis pe = pe2; 219865fc7c37SNikos Tsironis } 21992913808eSMikulas Patocka } 22001da177e4SLinus Torvalds 2201d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 220276df1c65SAlasdair G Kergon 2203515ad66cSMikulas Patocka /* 2204515ad66cSMikulas Patocka * If an origin bio was supplied, queue it to wait for the 2205515ad66cSMikulas Patocka * completion of this exception, and start this one last, 2206515ad66cSMikulas Patocka * at the end of the function. 2207515ad66cSMikulas Patocka */ 2208515ad66cSMikulas Patocka if (bio) { 2209515ad66cSMikulas Patocka bio_list_add(&pe->origin_bios, bio); 2210515ad66cSMikulas Patocka bio = NULL; 2211515ad66cSMikulas Patocka 2212515ad66cSMikulas Patocka if (!pe->started) { 2213515ad66cSMikulas Patocka pe->started = 1; 2214515ad66cSMikulas Patocka pe_to_start_last = pe; 2215515ad66cSMikulas Patocka } 2216b4b610f6SAlasdair G Kergon } 221776df1c65SAlasdair G Kergon 2218eccf0817SAlasdair G Kergon if (!pe->started) { 2219eccf0817SAlasdair G Kergon pe->started = 1; 2220515ad66cSMikulas Patocka pe_to_start_now = pe; 2221eccf0817SAlasdair G Kergon } 22221da177e4SLinus Torvalds 222376df1c65SAlasdair G Kergon next_snapshot: 2224ae1093beSMikulas Patocka mutex_unlock(&snap->lock); 2225515ad66cSMikulas Patocka 2226515ad66cSMikulas Patocka if (pe_to_start_now) { 2227515ad66cSMikulas Patocka start_copy(pe_to_start_now); 2228515ad66cSMikulas Patocka pe_to_start_now = NULL; 22291da177e4SLinus Torvalds } 2230b4b610f6SAlasdair G Kergon } 2231b4b610f6SAlasdair G Kergon 22321da177e4SLinus Torvalds /* 2233515ad66cSMikulas Patocka * Submit the exception against which the bio is queued last, 2234515ad66cSMikulas Patocka * to give the other exceptions a head start. 22351da177e4SLinus Torvalds */ 2236515ad66cSMikulas Patocka if (pe_to_start_last) 2237515ad66cSMikulas Patocka start_copy(pe_to_start_last); 22381da177e4SLinus Torvalds 22391da177e4SLinus Torvalds return r; 22401da177e4SLinus Torvalds } 22411da177e4SLinus Torvalds 22421da177e4SLinus Torvalds /* 22431da177e4SLinus Torvalds * Called on a write from the origin driver. 22441da177e4SLinus Torvalds */ 22451da177e4SLinus Torvalds static int do_origin(struct dm_dev *origin, struct bio *bio) 22461da177e4SLinus Torvalds { 22471da177e4SLinus Torvalds struct origin *o; 2248d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED; 22491da177e4SLinus Torvalds 22501da177e4SLinus Torvalds down_read(&_origins_lock); 22511da177e4SLinus Torvalds o = __lookup_origin(origin->bdev); 22521da177e4SLinus Torvalds if (o) 22534f024f37SKent Overstreet r = __origin_write(&o->snapshots, bio->bi_iter.bi_sector, bio); 22541da177e4SLinus Torvalds up_read(&_origins_lock); 22551da177e4SLinus Torvalds 22561da177e4SLinus Torvalds return r; 22571da177e4SLinus Torvalds } 22581da177e4SLinus Torvalds 22591da177e4SLinus Torvalds /* 226073dfd078SMikulas Patocka * Trigger exceptions in all non-merging snapshots. 226173dfd078SMikulas Patocka * 226273dfd078SMikulas Patocka * The chunk size of the merging snapshot may be larger than the chunk 226373dfd078SMikulas Patocka * size of some other snapshot so we may need to reallocate multiple 226473dfd078SMikulas Patocka * chunks in other snapshots. 226573dfd078SMikulas Patocka * 226673dfd078SMikulas Patocka * We scan all the overlapping exceptions in the other snapshots. 226773dfd078SMikulas Patocka * Returns 1 if anything was reallocated and must be waited for, 226873dfd078SMikulas Patocka * otherwise returns 0. 226973dfd078SMikulas Patocka * 227073dfd078SMikulas Patocka * size must be a multiple of merging_snap's chunk_size. 227173dfd078SMikulas Patocka */ 227273dfd078SMikulas Patocka static int origin_write_extent(struct dm_snapshot *merging_snap, 227373dfd078SMikulas Patocka sector_t sector, unsigned size) 227473dfd078SMikulas Patocka { 227573dfd078SMikulas Patocka int must_wait = 0; 227673dfd078SMikulas Patocka sector_t n; 227773dfd078SMikulas Patocka struct origin *o; 227873dfd078SMikulas Patocka 227973dfd078SMikulas Patocka /* 2280542f9038SMike Snitzer * The origin's __minimum_chunk_size() got stored in max_io_len 228173dfd078SMikulas Patocka * by snapshot_merge_resume(). 228273dfd078SMikulas Patocka */ 228373dfd078SMikulas Patocka down_read(&_origins_lock); 228473dfd078SMikulas Patocka o = __lookup_origin(merging_snap->origin->bdev); 2285542f9038SMike Snitzer for (n = 0; n < size; n += merging_snap->ti->max_io_len) 228673dfd078SMikulas Patocka if (__origin_write(&o->snapshots, sector + n, NULL) == 228773dfd078SMikulas Patocka DM_MAPIO_SUBMITTED) 228873dfd078SMikulas Patocka must_wait = 1; 228973dfd078SMikulas Patocka up_read(&_origins_lock); 229073dfd078SMikulas Patocka 229173dfd078SMikulas Patocka return must_wait; 229273dfd078SMikulas Patocka } 229373dfd078SMikulas Patocka 229473dfd078SMikulas Patocka /* 22951da177e4SLinus Torvalds * Origin: maps a linear range of a device, with hooks for snapshotting. 22961da177e4SLinus Torvalds */ 22971da177e4SLinus Torvalds 22981da177e4SLinus Torvalds /* 22991da177e4SLinus Torvalds * Construct an origin mapping: <dev_path> 23001da177e4SLinus Torvalds * The context for an origin is merely a 'struct dm_dev *' 23011da177e4SLinus Torvalds * pointing to the real device. 23021da177e4SLinus Torvalds */ 23031da177e4SLinus Torvalds static int origin_ctr(struct dm_target *ti, unsigned int argc, char **argv) 23041da177e4SLinus Torvalds { 23051da177e4SLinus Torvalds int r; 2306599cdf3bSMikulas Patocka struct dm_origin *o; 23071da177e4SLinus Torvalds 23081da177e4SLinus Torvalds if (argc != 1) { 230972d94861SAlasdair G Kergon ti->error = "origin: incorrect number of arguments"; 23101da177e4SLinus Torvalds return -EINVAL; 23111da177e4SLinus Torvalds } 23121da177e4SLinus Torvalds 2313599cdf3bSMikulas Patocka o = kmalloc(sizeof(struct dm_origin), GFP_KERNEL); 2314599cdf3bSMikulas Patocka if (!o) { 2315599cdf3bSMikulas Patocka ti->error = "Cannot allocate private origin structure"; 2316599cdf3bSMikulas Patocka r = -ENOMEM; 2317599cdf3bSMikulas Patocka goto bad_alloc; 23181da177e4SLinus Torvalds } 23191da177e4SLinus Torvalds 2320599cdf3bSMikulas Patocka r = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &o->dev); 2321599cdf3bSMikulas Patocka if (r) { 2322599cdf3bSMikulas Patocka ti->error = "Cannot get target device"; 2323599cdf3bSMikulas Patocka goto bad_open; 2324599cdf3bSMikulas Patocka } 2325599cdf3bSMikulas Patocka 2326b735fedeSMikulas Patocka o->ti = ti; 2327599cdf3bSMikulas Patocka ti->private = o; 232855a62eefSAlasdair G Kergon ti->num_flush_bios = 1; 2329494b3ee7SMikulas Patocka 23301da177e4SLinus Torvalds return 0; 2331599cdf3bSMikulas Patocka 2332599cdf3bSMikulas Patocka bad_open: 2333599cdf3bSMikulas Patocka kfree(o); 2334599cdf3bSMikulas Patocka bad_alloc: 2335599cdf3bSMikulas Patocka return r; 23361da177e4SLinus Torvalds } 23371da177e4SLinus Torvalds 23381da177e4SLinus Torvalds static void origin_dtr(struct dm_target *ti) 23391da177e4SLinus Torvalds { 2340599cdf3bSMikulas Patocka struct dm_origin *o = ti->private; 2341b735fedeSMikulas Patocka 2342599cdf3bSMikulas Patocka dm_put_device(ti, o->dev); 2343599cdf3bSMikulas Patocka kfree(o); 23441da177e4SLinus Torvalds } 23451da177e4SLinus Torvalds 23467de3ee57SMikulas Patocka static int origin_map(struct dm_target *ti, struct bio *bio) 23471da177e4SLinus Torvalds { 2348599cdf3bSMikulas Patocka struct dm_origin *o = ti->private; 2349298eaa89SMikulas Patocka unsigned available_sectors; 23501da177e4SLinus Torvalds 235174d46992SChristoph Hellwig bio_set_dev(bio, o->dev->bdev); 23521da177e4SLinus Torvalds 23531eff9d32SJens Axboe if (unlikely(bio->bi_opf & REQ_PREFLUSH)) 2354494b3ee7SMikulas Patocka return DM_MAPIO_REMAPPED; 2355494b3ee7SMikulas Patocka 235670246286SChristoph Hellwig if (bio_data_dir(bio) != WRITE) 2357298eaa89SMikulas Patocka return DM_MAPIO_REMAPPED; 2358298eaa89SMikulas Patocka 2359298eaa89SMikulas Patocka available_sectors = o->split_boundary - 2360298eaa89SMikulas Patocka ((unsigned)bio->bi_iter.bi_sector & (o->split_boundary - 1)); 2361298eaa89SMikulas Patocka 2362298eaa89SMikulas Patocka if (bio_sectors(bio) > available_sectors) 2363298eaa89SMikulas Patocka dm_accept_partial_bio(bio, available_sectors); 2364298eaa89SMikulas Patocka 23651da177e4SLinus Torvalds /* Only tell snapshots if this is a write */ 2366298eaa89SMikulas Patocka return do_origin(o->dev, bio); 23671da177e4SLinus Torvalds } 23681da177e4SLinus Torvalds 23691da177e4SLinus Torvalds /* 2370542f9038SMike Snitzer * Set the target "max_io_len" field to the minimum of all the snapshots' 23711da177e4SLinus Torvalds * chunk sizes. 23721da177e4SLinus Torvalds */ 23731da177e4SLinus Torvalds static void origin_resume(struct dm_target *ti) 23741da177e4SLinus Torvalds { 2375599cdf3bSMikulas Patocka struct dm_origin *o = ti->private; 23761da177e4SLinus Torvalds 2377298eaa89SMikulas Patocka o->split_boundary = get_origin_minimum_chunksize(o->dev->bdev); 2378b735fedeSMikulas Patocka 2379b735fedeSMikulas Patocka down_write(&_origins_lock); 2380b735fedeSMikulas Patocka __insert_dm_origin(o); 2381b735fedeSMikulas Patocka up_write(&_origins_lock); 2382b735fedeSMikulas Patocka } 2383b735fedeSMikulas Patocka 2384b735fedeSMikulas Patocka static void origin_postsuspend(struct dm_target *ti) 2385b735fedeSMikulas Patocka { 2386b735fedeSMikulas Patocka struct dm_origin *o = ti->private; 2387b735fedeSMikulas Patocka 2388b735fedeSMikulas Patocka down_write(&_origins_lock); 2389b735fedeSMikulas Patocka __remove_dm_origin(o); 2390b735fedeSMikulas Patocka up_write(&_origins_lock); 23911da177e4SLinus Torvalds } 23921da177e4SLinus Torvalds 2393fd7c092eSMikulas Patocka static void origin_status(struct dm_target *ti, status_type_t type, 23941f4e0ff0SAlasdair G Kergon unsigned status_flags, char *result, unsigned maxlen) 23951da177e4SLinus Torvalds { 2396599cdf3bSMikulas Patocka struct dm_origin *o = ti->private; 23971da177e4SLinus Torvalds 23981da177e4SLinus Torvalds switch (type) { 23991da177e4SLinus Torvalds case STATUSTYPE_INFO: 24001da177e4SLinus Torvalds result[0] = '\0'; 24011da177e4SLinus Torvalds break; 24021da177e4SLinus Torvalds 24031da177e4SLinus Torvalds case STATUSTYPE_TABLE: 2404599cdf3bSMikulas Patocka snprintf(result, maxlen, "%s", o->dev->name); 24051da177e4SLinus Torvalds break; 24061da177e4SLinus Torvalds } 24071da177e4SLinus Torvalds } 24081da177e4SLinus Torvalds 24098811f46cSMike Snitzer static int origin_iterate_devices(struct dm_target *ti, 24108811f46cSMike Snitzer iterate_devices_callout_fn fn, void *data) 24118811f46cSMike Snitzer { 2412599cdf3bSMikulas Patocka struct dm_origin *o = ti->private; 24138811f46cSMike Snitzer 2414599cdf3bSMikulas Patocka return fn(ti, o->dev, 0, ti->len, data); 24158811f46cSMike Snitzer } 24168811f46cSMike Snitzer 24171da177e4SLinus Torvalds static struct target_type origin_target = { 24181da177e4SLinus Torvalds .name = "snapshot-origin", 2419b735fedeSMikulas Patocka .version = {1, 9, 0}, 24201da177e4SLinus Torvalds .module = THIS_MODULE, 24211da177e4SLinus Torvalds .ctr = origin_ctr, 24221da177e4SLinus Torvalds .dtr = origin_dtr, 24231da177e4SLinus Torvalds .map = origin_map, 24241da177e4SLinus Torvalds .resume = origin_resume, 2425b735fedeSMikulas Patocka .postsuspend = origin_postsuspend, 24261da177e4SLinus Torvalds .status = origin_status, 24278811f46cSMike Snitzer .iterate_devices = origin_iterate_devices, 24281da177e4SLinus Torvalds }; 24291da177e4SLinus Torvalds 24301da177e4SLinus Torvalds static struct target_type snapshot_target = { 24311da177e4SLinus Torvalds .name = "snapshot", 2432b0d3cc01SMike Snitzer .version = {1, 15, 0}, 24331da177e4SLinus Torvalds .module = THIS_MODULE, 24341da177e4SLinus Torvalds .ctr = snapshot_ctr, 24351da177e4SLinus Torvalds .dtr = snapshot_dtr, 24361da177e4SLinus Torvalds .map = snapshot_map, 2437cd45daffSMikulas Patocka .end_io = snapshot_end_io, 2438c1f0c183SMike Snitzer .preresume = snapshot_preresume, 24391da177e4SLinus Torvalds .resume = snapshot_resume, 24401da177e4SLinus Torvalds .status = snapshot_status, 24418811f46cSMike Snitzer .iterate_devices = snapshot_iterate_devices, 24421da177e4SLinus Torvalds }; 24431da177e4SLinus Torvalds 2444d698aa45SMikulas Patocka static struct target_type merge_target = { 2445d698aa45SMikulas Patocka .name = dm_snapshot_merge_target_name, 2446b0d3cc01SMike Snitzer .version = {1, 4, 0}, 2447d698aa45SMikulas Patocka .module = THIS_MODULE, 2448d698aa45SMikulas Patocka .ctr = snapshot_ctr, 2449d698aa45SMikulas Patocka .dtr = snapshot_dtr, 24503452c2a1SMikulas Patocka .map = snapshot_merge_map, 2451d698aa45SMikulas Patocka .end_io = snapshot_end_io, 24521e03f97eSMikulas Patocka .presuspend = snapshot_merge_presuspend, 2453d698aa45SMikulas Patocka .preresume = snapshot_preresume, 24541e03f97eSMikulas Patocka .resume = snapshot_merge_resume, 2455d698aa45SMikulas Patocka .status = snapshot_status, 2456d698aa45SMikulas Patocka .iterate_devices = snapshot_iterate_devices, 2457d698aa45SMikulas Patocka }; 2458d698aa45SMikulas Patocka 24591da177e4SLinus Torvalds static int __init dm_snapshot_init(void) 24601da177e4SLinus Torvalds { 24611da177e4SLinus Torvalds int r; 24621da177e4SLinus Torvalds 24634db6bfe0SAlasdair G Kergon r = dm_exception_store_init(); 24644db6bfe0SAlasdair G Kergon if (r) { 24654db6bfe0SAlasdair G Kergon DMERR("Failed to initialize exception stores"); 24664db6bfe0SAlasdair G Kergon return r; 24674db6bfe0SAlasdair G Kergon } 24684db6bfe0SAlasdair G Kergon 24691da177e4SLinus Torvalds r = init_origin_hash(); 24701da177e4SLinus Torvalds if (r) { 24711da177e4SLinus Torvalds DMERR("init_origin_hash failed."); 2472d698aa45SMikulas Patocka goto bad_origin_hash; 24731da177e4SLinus Torvalds } 24741da177e4SLinus Torvalds 24751d4989c8SJon Brassow exception_cache = KMEM_CACHE(dm_exception, 0); 24761da177e4SLinus Torvalds if (!exception_cache) { 24771da177e4SLinus Torvalds DMERR("Couldn't create exception cache."); 24781da177e4SLinus Torvalds r = -ENOMEM; 2479d698aa45SMikulas Patocka goto bad_exception_cache; 24801da177e4SLinus Torvalds } 24811da177e4SLinus Torvalds 2482028867acSAlasdair G Kergon pending_cache = KMEM_CACHE(dm_snap_pending_exception, 0); 24831da177e4SLinus Torvalds if (!pending_cache) { 24841da177e4SLinus Torvalds DMERR("Couldn't create pending cache."); 24851da177e4SLinus Torvalds r = -ENOMEM; 2486d698aa45SMikulas Patocka goto bad_pending_cache; 24871da177e4SLinus Torvalds } 24881da177e4SLinus Torvalds 24897e6358d2Smonty_pavel@sina.com r = dm_register_target(&snapshot_target); 24907e6358d2Smonty_pavel@sina.com if (r < 0) { 24917e6358d2Smonty_pavel@sina.com DMERR("snapshot target register failed %d", r); 24927e6358d2Smonty_pavel@sina.com goto bad_register_snapshot_target; 24937e6358d2Smonty_pavel@sina.com } 24947e6358d2Smonty_pavel@sina.com 24957e6358d2Smonty_pavel@sina.com r = dm_register_target(&origin_target); 24967e6358d2Smonty_pavel@sina.com if (r < 0) { 24977e6358d2Smonty_pavel@sina.com DMERR("Origin target register failed %d", r); 24987e6358d2Smonty_pavel@sina.com goto bad_register_origin_target; 24997e6358d2Smonty_pavel@sina.com } 25007e6358d2Smonty_pavel@sina.com 25017e6358d2Smonty_pavel@sina.com r = dm_register_target(&merge_target); 25027e6358d2Smonty_pavel@sina.com if (r < 0) { 25037e6358d2Smonty_pavel@sina.com DMERR("Merge target register failed %d", r); 25047e6358d2Smonty_pavel@sina.com goto bad_register_merge_target; 25057e6358d2Smonty_pavel@sina.com } 25067e6358d2Smonty_pavel@sina.com 25071da177e4SLinus Torvalds return 0; 25081da177e4SLinus Torvalds 2509d698aa45SMikulas Patocka bad_register_merge_target: 25101da177e4SLinus Torvalds dm_unregister_target(&origin_target); 2511d698aa45SMikulas Patocka bad_register_origin_target: 25121da177e4SLinus Torvalds dm_unregister_target(&snapshot_target); 2513034a186dSJonathan Brassow bad_register_snapshot_target: 25147e6358d2Smonty_pavel@sina.com kmem_cache_destroy(pending_cache); 25157e6358d2Smonty_pavel@sina.com bad_pending_cache: 25167e6358d2Smonty_pavel@sina.com kmem_cache_destroy(exception_cache); 25177e6358d2Smonty_pavel@sina.com bad_exception_cache: 25187e6358d2Smonty_pavel@sina.com exit_origin_hash(); 25197e6358d2Smonty_pavel@sina.com bad_origin_hash: 2520034a186dSJonathan Brassow dm_exception_store_exit(); 2521d698aa45SMikulas Patocka 25221da177e4SLinus Torvalds return r; 25231da177e4SLinus Torvalds } 25241da177e4SLinus Torvalds 25251da177e4SLinus Torvalds static void __exit dm_snapshot_exit(void) 25261da177e4SLinus Torvalds { 252710d3bd09SMikulas Patocka dm_unregister_target(&snapshot_target); 252810d3bd09SMikulas Patocka dm_unregister_target(&origin_target); 2529d698aa45SMikulas Patocka dm_unregister_target(&merge_target); 25301da177e4SLinus Torvalds 25311da177e4SLinus Torvalds exit_origin_hash(); 25321da177e4SLinus Torvalds kmem_cache_destroy(pending_cache); 25331da177e4SLinus Torvalds kmem_cache_destroy(exception_cache); 25344db6bfe0SAlasdair G Kergon 25354db6bfe0SAlasdair G Kergon dm_exception_store_exit(); 25361da177e4SLinus Torvalds } 25371da177e4SLinus Torvalds 25381da177e4SLinus Torvalds /* Module hooks */ 25391da177e4SLinus Torvalds module_init(dm_snapshot_init); 25401da177e4SLinus Torvalds module_exit(dm_snapshot_exit); 25411da177e4SLinus Torvalds 25421da177e4SLinus Torvalds MODULE_DESCRIPTION(DM_NAME " snapshot target"); 25431da177e4SLinus Torvalds MODULE_AUTHOR("Joe Thornber"); 25441da177e4SLinus Torvalds MODULE_LICENSE("GPL"); 254523cb2109SMikulas Patocka MODULE_ALIAS("dm-snapshot-origin"); 254623cb2109SMikulas Patocka MODULE_ALIAS("dm-snapshot-merge"); 2547