11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * Copyright (C) 2001-2002 Sistina Software (UK) Limited. 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * This file is released under the GPL. 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds #include <linux/blkdev.h> 81da177e4SLinus Torvalds #include <linux/device-mapper.h> 990fa1527SMikulas Patocka #include <linux/delay.h> 101da177e4SLinus Torvalds #include <linux/fs.h> 111da177e4SLinus Torvalds #include <linux/init.h> 121da177e4SLinus Torvalds #include <linux/kdev_t.h> 131da177e4SLinus Torvalds #include <linux/list.h> 14f79ae415SNikos Tsironis #include <linux/list_bl.h> 151da177e4SLinus Torvalds #include <linux/mempool.h> 161da177e4SLinus Torvalds #include <linux/module.h> 171da177e4SLinus Torvalds #include <linux/slab.h> 181da177e4SLinus Torvalds #include <linux/vmalloc.h> 196f3c3f0aSvignesh babu #include <linux/log2.h> 20a765e20eSAlasdair G Kergon #include <linux/dm-kcopyd.h> 21721b1d98SNikos Tsironis #include <linux/semaphore.h> 221da177e4SLinus Torvalds 23b735fedeSMikulas Patocka #include "dm.h" 24b735fedeSMikulas Patocka 25aea53d92SJonathan Brassow #include "dm-exception-store.h" 261da177e4SLinus Torvalds 2772d94861SAlasdair G Kergon #define DM_MSG_PREFIX "snapshots" 2872d94861SAlasdair G Kergon 29d698aa45SMikulas Patocka static const char dm_snapshot_merge_target_name[] = "snapshot-merge"; 30d698aa45SMikulas Patocka 31d698aa45SMikulas Patocka #define dm_target_is_snapshot_merge(ti) \ 32d698aa45SMikulas Patocka ((ti)->type->name == dm_snapshot_merge_target_name) 33d698aa45SMikulas Patocka 341da177e4SLinus Torvalds /* 35cd45daffSMikulas Patocka * The size of the mempool used to track chunks in use. 36cd45daffSMikulas Patocka */ 37cd45daffSMikulas Patocka #define MIN_IOS 256 38cd45daffSMikulas Patocka 39ccc45ea8SJonathan Brassow #define DM_TRACKED_CHUNK_HASH_SIZE 16 40ccc45ea8SJonathan Brassow #define DM_TRACKED_CHUNK_HASH(x) ((unsigned long)(x) & \ 41ccc45ea8SJonathan Brassow (DM_TRACKED_CHUNK_HASH_SIZE - 1)) 42ccc45ea8SJonathan Brassow 43191437a5SJon Brassow struct dm_exception_table { 44ccc45ea8SJonathan Brassow uint32_t hash_mask; 45ccc45ea8SJonathan Brassow unsigned hash_shift; 46f79ae415SNikos Tsironis struct hlist_bl_head *table; 47ccc45ea8SJonathan Brassow }; 48ccc45ea8SJonathan Brassow 49ccc45ea8SJonathan Brassow struct dm_snapshot { 504ad8d880SNikos Tsironis struct rw_semaphore lock; 51ccc45ea8SJonathan Brassow 52ccc45ea8SJonathan Brassow struct dm_dev *origin; 53fc56f6fbSMike Snitzer struct dm_dev *cow; 54fc56f6fbSMike Snitzer 55fc56f6fbSMike Snitzer struct dm_target *ti; 56ccc45ea8SJonathan Brassow 57ccc45ea8SJonathan Brassow /* List of snapshots per Origin */ 58ccc45ea8SJonathan Brassow struct list_head list; 59ccc45ea8SJonathan Brassow 60d8ddb1cfSMike Snitzer /* 61d8ddb1cfSMike Snitzer * You can't use a snapshot if this is 0 (e.g. if full). 62d8ddb1cfSMike Snitzer * A snapshot-merge target never clears this. 63d8ddb1cfSMike Snitzer */ 64ccc45ea8SJonathan Brassow int valid; 65ccc45ea8SJonathan Brassow 6676c44f6dSMikulas Patocka /* 6776c44f6dSMikulas Patocka * The snapshot overflowed because of a write to the snapshot device. 6876c44f6dSMikulas Patocka * We don't have to invalidate the snapshot in this case, but we need 6976c44f6dSMikulas Patocka * to prevent further writes. 7076c44f6dSMikulas Patocka */ 7176c44f6dSMikulas Patocka int snapshot_overflowed; 7276c44f6dSMikulas Patocka 73ccc45ea8SJonathan Brassow /* Origin writes don't trigger exceptions until this is set */ 74ccc45ea8SJonathan Brassow int active; 75ccc45ea8SJonathan Brassow 76ccc45ea8SJonathan Brassow atomic_t pending_exceptions_count; 77ccc45ea8SJonathan Brassow 783f1637f2SNikos Tsironis spinlock_t pe_allocation_lock; 793f1637f2SNikos Tsironis 803f1637f2SNikos Tsironis /* Protected by "pe_allocation_lock" */ 81230c83afSMikulas Patocka sector_t exception_start_sequence; 82230c83afSMikulas Patocka 83230c83afSMikulas Patocka /* Protected by kcopyd single-threaded callback */ 84230c83afSMikulas Patocka sector_t exception_complete_sequence; 85230c83afSMikulas Patocka 86230c83afSMikulas Patocka /* 87230c83afSMikulas Patocka * A list of pending exceptions that completed out of order. 88230c83afSMikulas Patocka * Protected by kcopyd single-threaded callback. 89230c83afSMikulas Patocka */ 903db2776dSDavid Jeffery struct rb_root out_of_order_tree; 91230c83afSMikulas Patocka 926f1c819cSKent Overstreet mempool_t pending_pool; 93924e600dSMike Snitzer 94191437a5SJon Brassow struct dm_exception_table pending; 95191437a5SJon Brassow struct dm_exception_table complete; 96ccc45ea8SJonathan Brassow 97ccc45ea8SJonathan Brassow /* 98ccc45ea8SJonathan Brassow * pe_lock protects all pending_exception operations and access 99ccc45ea8SJonathan Brassow * as well as the snapshot_bios list. 100ccc45ea8SJonathan Brassow */ 101ccc45ea8SJonathan Brassow spinlock_t pe_lock; 102ccc45ea8SJonathan Brassow 103924e600dSMike Snitzer /* Chunks with outstanding reads */ 104924e600dSMike Snitzer spinlock_t tracked_chunk_lock; 105924e600dSMike Snitzer struct hlist_head tracked_chunk_hash[DM_TRACKED_CHUNK_HASH_SIZE]; 106924e600dSMike Snitzer 107ccc45ea8SJonathan Brassow /* The on disk metadata handler */ 108ccc45ea8SJonathan Brassow struct dm_exception_store *store; 109ccc45ea8SJonathan Brassow 110721b1d98SNikos Tsironis /* Maximum number of in-flight COW jobs. */ 111721b1d98SNikos Tsironis struct semaphore cow_count; 112721b1d98SNikos Tsironis 113ccc45ea8SJonathan Brassow struct dm_kcopyd_client *kcopyd_client; 114ccc45ea8SJonathan Brassow 115924e600dSMike Snitzer /* Wait for events based on state_bits */ 116924e600dSMike Snitzer unsigned long state_bits; 117924e600dSMike Snitzer 118924e600dSMike Snitzer /* Range of chunks currently being merged. */ 119924e600dSMike Snitzer chunk_t first_merging_chunk; 120924e600dSMike Snitzer int num_merging_chunks; 1211e03f97eSMikulas Patocka 122d8ddb1cfSMike Snitzer /* 123d8ddb1cfSMike Snitzer * The merge operation failed if this flag is set. 124d8ddb1cfSMike Snitzer * Failure modes are handled as follows: 125d8ddb1cfSMike Snitzer * - I/O error reading the header 126d8ddb1cfSMike Snitzer * => don't load the target; abort. 127d8ddb1cfSMike Snitzer * - Header does not have "valid" flag set 128d8ddb1cfSMike Snitzer * => use the origin; forget about the snapshot. 129d8ddb1cfSMike Snitzer * - I/O error when reading exceptions 130d8ddb1cfSMike Snitzer * => don't load the target; abort. 131d8ddb1cfSMike Snitzer * (We can't use the intermediate origin state.) 132d8ddb1cfSMike Snitzer * - I/O error while merging 133d8ddb1cfSMike Snitzer * => stop merging; set merge_failed; process I/O normally. 134d8ddb1cfSMike Snitzer */ 1352e602385SMike Snitzer bool merge_failed:1; 1362e602385SMike Snitzer 1372e602385SMike Snitzer bool discard_zeroes_cow:1; 1382e602385SMike Snitzer bool discard_passdown_origin:1; 139d8ddb1cfSMike Snitzer 1409fe86254SMikulas Patocka /* 1419fe86254SMikulas Patocka * Incoming bios that overlap with chunks being merged must wait 1429fe86254SMikulas Patocka * for them to be committed. 1439fe86254SMikulas Patocka */ 1449fe86254SMikulas Patocka struct bio_list bios_queued_during_merge; 145ccc45ea8SJonathan Brassow }; 146ccc45ea8SJonathan Brassow 1471e03f97eSMikulas Patocka /* 1481e03f97eSMikulas Patocka * state_bits: 1491e03f97eSMikulas Patocka * RUNNING_MERGE - Merge operation is in progress. 1501e03f97eSMikulas Patocka * SHUTDOWN_MERGE - Set to signal that merge needs to be stopped; 1511e03f97eSMikulas Patocka * cleared afterwards. 1521e03f97eSMikulas Patocka */ 1531e03f97eSMikulas Patocka #define RUNNING_MERGE 0 1541e03f97eSMikulas Patocka #define SHUTDOWN_MERGE 1 1551e03f97eSMikulas Patocka 156721b1d98SNikos Tsironis /* 157721b1d98SNikos Tsironis * Maximum number of chunks being copied on write. 158721b1d98SNikos Tsironis * 159721b1d98SNikos Tsironis * The value was decided experimentally as a trade-off between memory 160721b1d98SNikos Tsironis * consumption, stalling the kernel's workqueues and maintaining a high enough 161721b1d98SNikos Tsironis * throughput. 162721b1d98SNikos Tsironis */ 163721b1d98SNikos Tsironis #define DEFAULT_COW_THRESHOLD 2048 164721b1d98SNikos Tsironis 165721b1d98SNikos Tsironis static int cow_threshold = DEFAULT_COW_THRESHOLD; 166721b1d98SNikos Tsironis module_param_named(snapshot_cow_threshold, cow_threshold, int, 0644); 167721b1d98SNikos Tsironis MODULE_PARM_DESC(snapshot_cow_threshold, "Maximum number of chunks being copied on write"); 168721b1d98SNikos Tsironis 169df5d2e90SMikulas Patocka DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(snapshot_copy_throttle, 170df5d2e90SMikulas Patocka "A percentage of time allocated for copy on write"); 171df5d2e90SMikulas Patocka 172c2411045SMikulas Patocka struct dm_dev *dm_snap_origin(struct dm_snapshot *s) 173c2411045SMikulas Patocka { 174c2411045SMikulas Patocka return s->origin; 175c2411045SMikulas Patocka } 176c2411045SMikulas Patocka EXPORT_SYMBOL(dm_snap_origin); 177c2411045SMikulas Patocka 178fc56f6fbSMike Snitzer struct dm_dev *dm_snap_cow(struct dm_snapshot *s) 179fc56f6fbSMike Snitzer { 180fc56f6fbSMike Snitzer return s->cow; 181fc56f6fbSMike Snitzer } 182fc56f6fbSMike Snitzer EXPORT_SYMBOL(dm_snap_cow); 183fc56f6fbSMike Snitzer 184ccc45ea8SJonathan Brassow static sector_t chunk_to_sector(struct dm_exception_store *store, 185ccc45ea8SJonathan Brassow chunk_t chunk) 186ccc45ea8SJonathan Brassow { 187ccc45ea8SJonathan Brassow return chunk << store->chunk_shift; 188ccc45ea8SJonathan Brassow } 189ccc45ea8SJonathan Brassow 190ccc45ea8SJonathan Brassow static int bdev_equal(struct block_device *lhs, struct block_device *rhs) 191ccc45ea8SJonathan Brassow { 192ccc45ea8SJonathan Brassow /* 193ccc45ea8SJonathan Brassow * There is only ever one instance of a particular block 194ccc45ea8SJonathan Brassow * device so we can compare pointers safely. 195ccc45ea8SJonathan Brassow */ 196ccc45ea8SJonathan Brassow return lhs == rhs; 197ccc45ea8SJonathan Brassow } 198ccc45ea8SJonathan Brassow 199028867acSAlasdair G Kergon struct dm_snap_pending_exception { 2001d4989c8SJon Brassow struct dm_exception e; 2011da177e4SLinus Torvalds 2021da177e4SLinus Torvalds /* 2031da177e4SLinus Torvalds * Origin buffers waiting for this to complete are held 2041da177e4SLinus Torvalds * in a bio list 2051da177e4SLinus Torvalds */ 2061da177e4SLinus Torvalds struct bio_list origin_bios; 2071da177e4SLinus Torvalds struct bio_list snapshot_bios; 2081da177e4SLinus Torvalds 2091da177e4SLinus Torvalds /* Pointer back to snapshot context */ 2101da177e4SLinus Torvalds struct dm_snapshot *snap; 2111da177e4SLinus Torvalds 2121da177e4SLinus Torvalds /* 2131da177e4SLinus Torvalds * 1 indicates the exception has already been sent to 2141da177e4SLinus Torvalds * kcopyd. 2151da177e4SLinus Torvalds */ 2161da177e4SLinus Torvalds int started; 217a6e50b40SMikulas Patocka 218230c83afSMikulas Patocka /* There was copying error. */ 219230c83afSMikulas Patocka int copy_error; 220230c83afSMikulas Patocka 221230c83afSMikulas Patocka /* A sequence number, it is used for in-order completion. */ 222230c83afSMikulas Patocka sector_t exception_sequence; 223230c83afSMikulas Patocka 2243db2776dSDavid Jeffery struct rb_node out_of_order_node; 225230c83afSMikulas Patocka 226a6e50b40SMikulas Patocka /* 227a6e50b40SMikulas Patocka * For writing a complete chunk, bypassing the copy. 228a6e50b40SMikulas Patocka */ 229a6e50b40SMikulas Patocka struct bio *full_bio; 230a6e50b40SMikulas Patocka bio_end_io_t *full_bio_end_io; 2311da177e4SLinus Torvalds }; 2321da177e4SLinus Torvalds 2331da177e4SLinus Torvalds /* 2341da177e4SLinus Torvalds * Hash table mapping origin volumes to lists of snapshots and 2351da177e4SLinus Torvalds * a lock to protect it 2361da177e4SLinus Torvalds */ 237e18b890bSChristoph Lameter static struct kmem_cache *exception_cache; 238e18b890bSChristoph Lameter static struct kmem_cache *pending_cache; 2391da177e4SLinus Torvalds 240cd45daffSMikulas Patocka struct dm_snap_tracked_chunk { 241cd45daffSMikulas Patocka struct hlist_node node; 242cd45daffSMikulas Patocka chunk_t chunk; 243cd45daffSMikulas Patocka }; 244cd45daffSMikulas Patocka 245ee18026aSMikulas Patocka static void init_tracked_chunk(struct bio *bio) 246ee18026aSMikulas Patocka { 247ee18026aSMikulas Patocka struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk)); 248ee18026aSMikulas Patocka INIT_HLIST_NODE(&c->node); 249ee18026aSMikulas Patocka } 250ee18026aSMikulas Patocka 251ee18026aSMikulas Patocka static bool is_bio_tracked(struct bio *bio) 252ee18026aSMikulas Patocka { 253ee18026aSMikulas Patocka struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk)); 254ee18026aSMikulas Patocka return !hlist_unhashed(&c->node); 255ee18026aSMikulas Patocka } 256ee18026aSMikulas Patocka 257ee18026aSMikulas Patocka static void track_chunk(struct dm_snapshot *s, struct bio *bio, chunk_t chunk) 258cd45daffSMikulas Patocka { 25942bc954fSMikulas Patocka struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk)); 260cd45daffSMikulas Patocka 261cd45daffSMikulas Patocka c->chunk = chunk; 262cd45daffSMikulas Patocka 2639aa0c0e6SMikulas Patocka spin_lock_irq(&s->tracked_chunk_lock); 264cd45daffSMikulas Patocka hlist_add_head(&c->node, 265cd45daffSMikulas Patocka &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)]); 2669aa0c0e6SMikulas Patocka spin_unlock_irq(&s->tracked_chunk_lock); 267cd45daffSMikulas Patocka } 268cd45daffSMikulas Patocka 269ee18026aSMikulas Patocka static void stop_tracking_chunk(struct dm_snapshot *s, struct bio *bio) 270cd45daffSMikulas Patocka { 271ee18026aSMikulas Patocka struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk)); 272cd45daffSMikulas Patocka unsigned long flags; 273cd45daffSMikulas Patocka 274cd45daffSMikulas Patocka spin_lock_irqsave(&s->tracked_chunk_lock, flags); 275cd45daffSMikulas Patocka hlist_del(&c->node); 276cd45daffSMikulas Patocka spin_unlock_irqrestore(&s->tracked_chunk_lock, flags); 277cd45daffSMikulas Patocka } 278cd45daffSMikulas Patocka 279a8d41b59SMikulas Patocka static int __chunk_is_tracked(struct dm_snapshot *s, chunk_t chunk) 280a8d41b59SMikulas Patocka { 281a8d41b59SMikulas Patocka struct dm_snap_tracked_chunk *c; 282a8d41b59SMikulas Patocka int found = 0; 283a8d41b59SMikulas Patocka 284a8d41b59SMikulas Patocka spin_lock_irq(&s->tracked_chunk_lock); 285a8d41b59SMikulas Patocka 286b67bfe0dSSasha Levin hlist_for_each_entry(c, 287a8d41b59SMikulas Patocka &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)], node) { 288a8d41b59SMikulas Patocka if (c->chunk == chunk) { 289a8d41b59SMikulas Patocka found = 1; 290a8d41b59SMikulas Patocka break; 291a8d41b59SMikulas Patocka } 292a8d41b59SMikulas Patocka } 293a8d41b59SMikulas Patocka 294a8d41b59SMikulas Patocka spin_unlock_irq(&s->tracked_chunk_lock); 295a8d41b59SMikulas Patocka 296a8d41b59SMikulas Patocka return found; 297a8d41b59SMikulas Patocka } 298a8d41b59SMikulas Patocka 2991da177e4SLinus Torvalds /* 300615d1eb9SMike Snitzer * This conflicting I/O is extremely improbable in the caller, 301615d1eb9SMike Snitzer * so msleep(1) is sufficient and there is no need for a wait queue. 302615d1eb9SMike Snitzer */ 303615d1eb9SMike Snitzer static void __check_for_conflicting_io(struct dm_snapshot *s, chunk_t chunk) 304615d1eb9SMike Snitzer { 305615d1eb9SMike Snitzer while (__chunk_is_tracked(s, chunk)) 306615d1eb9SMike Snitzer msleep(1); 307615d1eb9SMike Snitzer } 308615d1eb9SMike Snitzer 309615d1eb9SMike Snitzer /* 3101da177e4SLinus Torvalds * One of these per registered origin, held in the snapshot_origins hash 3111da177e4SLinus Torvalds */ 3121da177e4SLinus Torvalds struct origin { 3131da177e4SLinus Torvalds /* The origin device */ 3141da177e4SLinus Torvalds struct block_device *bdev; 3151da177e4SLinus Torvalds 3161da177e4SLinus Torvalds struct list_head hash_list; 3171da177e4SLinus Torvalds 3181da177e4SLinus Torvalds /* List of snapshots for this origin */ 3191da177e4SLinus Torvalds struct list_head snapshots; 3201da177e4SLinus Torvalds }; 3211da177e4SLinus Torvalds 3221da177e4SLinus Torvalds /* 323b735fedeSMikulas Patocka * This structure is allocated for each origin target 324b735fedeSMikulas Patocka */ 325b735fedeSMikulas Patocka struct dm_origin { 326b735fedeSMikulas Patocka struct dm_dev *dev; 327b735fedeSMikulas Patocka struct dm_target *ti; 328b735fedeSMikulas Patocka unsigned split_boundary; 329b735fedeSMikulas Patocka struct list_head hash_list; 330b735fedeSMikulas Patocka }; 331b735fedeSMikulas Patocka 332b735fedeSMikulas Patocka /* 3331da177e4SLinus Torvalds * Size of the hash table for origin volumes. If we make this 3341da177e4SLinus Torvalds * the size of the minors list then it should be nearly perfect 3351da177e4SLinus Torvalds */ 3361da177e4SLinus Torvalds #define ORIGIN_HASH_SIZE 256 3371da177e4SLinus Torvalds #define ORIGIN_MASK 0xFF 3381da177e4SLinus Torvalds static struct list_head *_origins; 339b735fedeSMikulas Patocka static struct list_head *_dm_origins; 3401da177e4SLinus Torvalds static struct rw_semaphore _origins_lock; 3411da177e4SLinus Torvalds 34273dfd078SMikulas Patocka static DECLARE_WAIT_QUEUE_HEAD(_pending_exceptions_done); 34373dfd078SMikulas Patocka static DEFINE_SPINLOCK(_pending_exceptions_done_spinlock); 34473dfd078SMikulas Patocka static uint64_t _pending_exceptions_done_count; 34573dfd078SMikulas Patocka 3461da177e4SLinus Torvalds static int init_origin_hash(void) 3471da177e4SLinus Torvalds { 3481da177e4SLinus Torvalds int i; 3491da177e4SLinus Torvalds 3506da2ec56SKees Cook _origins = kmalloc_array(ORIGIN_HASH_SIZE, sizeof(struct list_head), 3511da177e4SLinus Torvalds GFP_KERNEL); 3521da177e4SLinus Torvalds if (!_origins) { 353b735fedeSMikulas Patocka DMERR("unable to allocate memory for _origins"); 3541da177e4SLinus Torvalds return -ENOMEM; 3551da177e4SLinus Torvalds } 3561da177e4SLinus Torvalds for (i = 0; i < ORIGIN_HASH_SIZE; i++) 3571da177e4SLinus Torvalds INIT_LIST_HEAD(_origins + i); 358b735fedeSMikulas Patocka 3596da2ec56SKees Cook _dm_origins = kmalloc_array(ORIGIN_HASH_SIZE, 3606da2ec56SKees Cook sizeof(struct list_head), 361b735fedeSMikulas Patocka GFP_KERNEL); 362b735fedeSMikulas Patocka if (!_dm_origins) { 363b735fedeSMikulas Patocka DMERR("unable to allocate memory for _dm_origins"); 364b735fedeSMikulas Patocka kfree(_origins); 365b735fedeSMikulas Patocka return -ENOMEM; 366b735fedeSMikulas Patocka } 367b735fedeSMikulas Patocka for (i = 0; i < ORIGIN_HASH_SIZE; i++) 368b735fedeSMikulas Patocka INIT_LIST_HEAD(_dm_origins + i); 369b735fedeSMikulas Patocka 3701da177e4SLinus Torvalds init_rwsem(&_origins_lock); 3711da177e4SLinus Torvalds 3721da177e4SLinus Torvalds return 0; 3731da177e4SLinus Torvalds } 3741da177e4SLinus Torvalds 3751da177e4SLinus Torvalds static void exit_origin_hash(void) 3761da177e4SLinus Torvalds { 3771da177e4SLinus Torvalds kfree(_origins); 378b735fedeSMikulas Patocka kfree(_dm_origins); 3791da177e4SLinus Torvalds } 3801da177e4SLinus Torvalds 381028867acSAlasdair G Kergon static unsigned origin_hash(struct block_device *bdev) 3821da177e4SLinus Torvalds { 3831da177e4SLinus Torvalds return bdev->bd_dev & ORIGIN_MASK; 3841da177e4SLinus Torvalds } 3851da177e4SLinus Torvalds 3861da177e4SLinus Torvalds static struct origin *__lookup_origin(struct block_device *origin) 3871da177e4SLinus Torvalds { 3881da177e4SLinus Torvalds struct list_head *ol; 3891da177e4SLinus Torvalds struct origin *o; 3901da177e4SLinus Torvalds 3911da177e4SLinus Torvalds ol = &_origins[origin_hash(origin)]; 3921da177e4SLinus Torvalds list_for_each_entry (o, ol, hash_list) 3931da177e4SLinus Torvalds if (bdev_equal(o->bdev, origin)) 3941da177e4SLinus Torvalds return o; 3951da177e4SLinus Torvalds 3961da177e4SLinus Torvalds return NULL; 3971da177e4SLinus Torvalds } 3981da177e4SLinus Torvalds 3991da177e4SLinus Torvalds static void __insert_origin(struct origin *o) 4001da177e4SLinus Torvalds { 4011da177e4SLinus Torvalds struct list_head *sl = &_origins[origin_hash(o->bdev)]; 4021da177e4SLinus Torvalds list_add_tail(&o->hash_list, sl); 4031da177e4SLinus Torvalds } 4041da177e4SLinus Torvalds 405b735fedeSMikulas Patocka static struct dm_origin *__lookup_dm_origin(struct block_device *origin) 406b735fedeSMikulas Patocka { 407b735fedeSMikulas Patocka struct list_head *ol; 408b735fedeSMikulas Patocka struct dm_origin *o; 409b735fedeSMikulas Patocka 410b735fedeSMikulas Patocka ol = &_dm_origins[origin_hash(origin)]; 411b735fedeSMikulas Patocka list_for_each_entry (o, ol, hash_list) 412b735fedeSMikulas Patocka if (bdev_equal(o->dev->bdev, origin)) 413b735fedeSMikulas Patocka return o; 414b735fedeSMikulas Patocka 415b735fedeSMikulas Patocka return NULL; 416b735fedeSMikulas Patocka } 417b735fedeSMikulas Patocka 418b735fedeSMikulas Patocka static void __insert_dm_origin(struct dm_origin *o) 419b735fedeSMikulas Patocka { 420b735fedeSMikulas Patocka struct list_head *sl = &_dm_origins[origin_hash(o->dev->bdev)]; 421b735fedeSMikulas Patocka list_add_tail(&o->hash_list, sl); 422b735fedeSMikulas Patocka } 423b735fedeSMikulas Patocka 424b735fedeSMikulas Patocka static void __remove_dm_origin(struct dm_origin *o) 425b735fedeSMikulas Patocka { 426b735fedeSMikulas Patocka list_del(&o->hash_list); 427b735fedeSMikulas Patocka } 428b735fedeSMikulas Patocka 4291da177e4SLinus Torvalds /* 430c1f0c183SMike Snitzer * _origins_lock must be held when calling this function. 431c1f0c183SMike Snitzer * Returns number of snapshots registered using the supplied cow device, plus: 432c1f0c183SMike Snitzer * snap_src - a snapshot suitable for use as a source of exception handover 433c1f0c183SMike Snitzer * snap_dest - a snapshot capable of receiving exception handover. 4349d3b15c4SMikulas Patocka * snap_merge - an existing snapshot-merge target linked to the same origin. 4359d3b15c4SMikulas Patocka * There can be at most one snapshot-merge target. The parameter is optional. 436c1f0c183SMike Snitzer * 4379d3b15c4SMikulas Patocka * Possible return values and states of snap_src and snap_dest. 438c1f0c183SMike Snitzer * 0: NULL, NULL - first new snapshot 439c1f0c183SMike Snitzer * 1: snap_src, NULL - normal snapshot 440c1f0c183SMike Snitzer * 2: snap_src, snap_dest - waiting for handover 441c1f0c183SMike Snitzer * 2: snap_src, NULL - handed over, waiting for old to be deleted 442c1f0c183SMike Snitzer * 1: NULL, snap_dest - source got destroyed without handover 443c1f0c183SMike Snitzer */ 444c1f0c183SMike Snitzer static int __find_snapshots_sharing_cow(struct dm_snapshot *snap, 445c1f0c183SMike Snitzer struct dm_snapshot **snap_src, 4469d3b15c4SMikulas Patocka struct dm_snapshot **snap_dest, 4479d3b15c4SMikulas Patocka struct dm_snapshot **snap_merge) 448c1f0c183SMike Snitzer { 449c1f0c183SMike Snitzer struct dm_snapshot *s; 450c1f0c183SMike Snitzer struct origin *o; 451c1f0c183SMike Snitzer int count = 0; 452c1f0c183SMike Snitzer int active; 453c1f0c183SMike Snitzer 454c1f0c183SMike Snitzer o = __lookup_origin(snap->origin->bdev); 455c1f0c183SMike Snitzer if (!o) 456c1f0c183SMike Snitzer goto out; 457c1f0c183SMike Snitzer 458c1f0c183SMike Snitzer list_for_each_entry(s, &o->snapshots, list) { 4599d3b15c4SMikulas Patocka if (dm_target_is_snapshot_merge(s->ti) && snap_merge) 4609d3b15c4SMikulas Patocka *snap_merge = s; 461c1f0c183SMike Snitzer if (!bdev_equal(s->cow->bdev, snap->cow->bdev)) 462c1f0c183SMike Snitzer continue; 463c1f0c183SMike Snitzer 4644ad8d880SNikos Tsironis down_read(&s->lock); 465c1f0c183SMike Snitzer active = s->active; 4664ad8d880SNikos Tsironis up_read(&s->lock); 467c1f0c183SMike Snitzer 468c1f0c183SMike Snitzer if (active) { 469c1f0c183SMike Snitzer if (snap_src) 470c1f0c183SMike Snitzer *snap_src = s; 471c1f0c183SMike Snitzer } else if (snap_dest) 472c1f0c183SMike Snitzer *snap_dest = s; 473c1f0c183SMike Snitzer 474c1f0c183SMike Snitzer count++; 475c1f0c183SMike Snitzer } 476c1f0c183SMike Snitzer 477c1f0c183SMike Snitzer out: 478c1f0c183SMike Snitzer return count; 479c1f0c183SMike Snitzer } 480c1f0c183SMike Snitzer 481c1f0c183SMike Snitzer /* 482c1f0c183SMike Snitzer * On success, returns 1 if this snapshot is a handover destination, 483c1f0c183SMike Snitzer * otherwise returns 0. 484c1f0c183SMike Snitzer */ 485c1f0c183SMike Snitzer static int __validate_exception_handover(struct dm_snapshot *snap) 486c1f0c183SMike Snitzer { 487c1f0c183SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 4889d3b15c4SMikulas Patocka struct dm_snapshot *snap_merge = NULL; 489c1f0c183SMike Snitzer 490c1f0c183SMike Snitzer /* Does snapshot need exceptions handed over to it? */ 4919d3b15c4SMikulas Patocka if ((__find_snapshots_sharing_cow(snap, &snap_src, &snap_dest, 4929d3b15c4SMikulas Patocka &snap_merge) == 2) || 493c1f0c183SMike Snitzer snap_dest) { 494c1f0c183SMike Snitzer snap->ti->error = "Snapshot cow pairing for exception " 495c1f0c183SMike Snitzer "table handover failed"; 496c1f0c183SMike Snitzer return -EINVAL; 497c1f0c183SMike Snitzer } 498c1f0c183SMike Snitzer 499c1f0c183SMike Snitzer /* 500c1f0c183SMike Snitzer * If no snap_src was found, snap cannot become a handover 501c1f0c183SMike Snitzer * destination. 502c1f0c183SMike Snitzer */ 503c1f0c183SMike Snitzer if (!snap_src) 504c1f0c183SMike Snitzer return 0; 505c1f0c183SMike Snitzer 5069d3b15c4SMikulas Patocka /* 5079d3b15c4SMikulas Patocka * Non-snapshot-merge handover? 5089d3b15c4SMikulas Patocka */ 5099d3b15c4SMikulas Patocka if (!dm_target_is_snapshot_merge(snap->ti)) 5109d3b15c4SMikulas Patocka return 1; 5119d3b15c4SMikulas Patocka 5129d3b15c4SMikulas Patocka /* 5139d3b15c4SMikulas Patocka * Do not allow more than one merging snapshot. 5149d3b15c4SMikulas Patocka */ 5159d3b15c4SMikulas Patocka if (snap_merge) { 5169d3b15c4SMikulas Patocka snap->ti->error = "A snapshot is already merging."; 5179d3b15c4SMikulas Patocka return -EINVAL; 5189d3b15c4SMikulas Patocka } 5199d3b15c4SMikulas Patocka 5201e03f97eSMikulas Patocka if (!snap_src->store->type->prepare_merge || 5211e03f97eSMikulas Patocka !snap_src->store->type->commit_merge) { 5221e03f97eSMikulas Patocka snap->ti->error = "Snapshot exception store does not " 5231e03f97eSMikulas Patocka "support snapshot-merge."; 5241e03f97eSMikulas Patocka return -EINVAL; 5251e03f97eSMikulas Patocka } 5261e03f97eSMikulas Patocka 527c1f0c183SMike Snitzer return 1; 528c1f0c183SMike Snitzer } 529c1f0c183SMike Snitzer 530c1f0c183SMike Snitzer static void __insert_snapshot(struct origin *o, struct dm_snapshot *s) 531c1f0c183SMike Snitzer { 532c1f0c183SMike Snitzer struct dm_snapshot *l; 533c1f0c183SMike Snitzer 534c1f0c183SMike Snitzer /* Sort the list according to chunk size, largest-first smallest-last */ 535c1f0c183SMike Snitzer list_for_each_entry(l, &o->snapshots, list) 536c1f0c183SMike Snitzer if (l->store->chunk_size < s->store->chunk_size) 537c1f0c183SMike Snitzer break; 538c1f0c183SMike Snitzer list_add_tail(&s->list, &l->list); 539c1f0c183SMike Snitzer } 540c1f0c183SMike Snitzer 541c1f0c183SMike Snitzer /* 5421da177e4SLinus Torvalds * Make a note of the snapshot and its origin so we can look it 5431da177e4SLinus Torvalds * up when the origin has a write on it. 544c1f0c183SMike Snitzer * 545c1f0c183SMike Snitzer * Also validate snapshot exception store handovers. 546c1f0c183SMike Snitzer * On success, returns 1 if this registration is a handover destination, 547c1f0c183SMike Snitzer * otherwise returns 0. 5481da177e4SLinus Torvalds */ 5491da177e4SLinus Torvalds static int register_snapshot(struct dm_snapshot *snap) 5501da177e4SLinus Torvalds { 551c1f0c183SMike Snitzer struct origin *o, *new_o = NULL; 5521da177e4SLinus Torvalds struct block_device *bdev = snap->origin->bdev; 553c1f0c183SMike Snitzer int r = 0; 5541da177e4SLinus Torvalds 55560c856c8SMikulas Patocka new_o = kmalloc(sizeof(*new_o), GFP_KERNEL); 55660c856c8SMikulas Patocka if (!new_o) 55760c856c8SMikulas Patocka return -ENOMEM; 55860c856c8SMikulas Patocka 5591da177e4SLinus Torvalds down_write(&_origins_lock); 5601da177e4SLinus Torvalds 561c1f0c183SMike Snitzer r = __validate_exception_handover(snap); 562c1f0c183SMike Snitzer if (r < 0) { 563c1f0c183SMike Snitzer kfree(new_o); 564c1f0c183SMike Snitzer goto out; 565c1f0c183SMike Snitzer } 566c1f0c183SMike Snitzer 567c1f0c183SMike Snitzer o = __lookup_origin(bdev); 56860c856c8SMikulas Patocka if (o) 56960c856c8SMikulas Patocka kfree(new_o); 57060c856c8SMikulas Patocka else { 5711da177e4SLinus Torvalds /* New origin */ 57260c856c8SMikulas Patocka o = new_o; 5731da177e4SLinus Torvalds 5741da177e4SLinus Torvalds /* Initialise the struct */ 5751da177e4SLinus Torvalds INIT_LIST_HEAD(&o->snapshots); 5761da177e4SLinus Torvalds o->bdev = bdev; 5771da177e4SLinus Torvalds 5781da177e4SLinus Torvalds __insert_origin(o); 5791da177e4SLinus Torvalds } 5801da177e4SLinus Torvalds 581c1f0c183SMike Snitzer __insert_snapshot(o, snap); 582c1f0c183SMike Snitzer 583c1f0c183SMike Snitzer out: 584c1f0c183SMike Snitzer up_write(&_origins_lock); 585c1f0c183SMike Snitzer 586c1f0c183SMike Snitzer return r; 587c1f0c183SMike Snitzer } 588c1f0c183SMike Snitzer 589c1f0c183SMike Snitzer /* 590c1f0c183SMike Snitzer * Move snapshot to correct place in list according to chunk size. 591c1f0c183SMike Snitzer */ 592c1f0c183SMike Snitzer static void reregister_snapshot(struct dm_snapshot *s) 593c1f0c183SMike Snitzer { 594c1f0c183SMike Snitzer struct block_device *bdev = s->origin->bdev; 595c1f0c183SMike Snitzer 596c1f0c183SMike Snitzer down_write(&_origins_lock); 597c1f0c183SMike Snitzer 598c1f0c183SMike Snitzer list_del(&s->list); 599c1f0c183SMike Snitzer __insert_snapshot(__lookup_origin(bdev), s); 6001da177e4SLinus Torvalds 6011da177e4SLinus Torvalds up_write(&_origins_lock); 6021da177e4SLinus Torvalds } 6031da177e4SLinus Torvalds 6041da177e4SLinus Torvalds static void unregister_snapshot(struct dm_snapshot *s) 6051da177e4SLinus Torvalds { 6061da177e4SLinus Torvalds struct origin *o; 6071da177e4SLinus Torvalds 6081da177e4SLinus Torvalds down_write(&_origins_lock); 6091da177e4SLinus Torvalds o = __lookup_origin(s->origin->bdev); 6101da177e4SLinus Torvalds 6111da177e4SLinus Torvalds list_del(&s->list); 612c1f0c183SMike Snitzer if (o && list_empty(&o->snapshots)) { 6131da177e4SLinus Torvalds list_del(&o->hash_list); 6141da177e4SLinus Torvalds kfree(o); 6151da177e4SLinus Torvalds } 6161da177e4SLinus Torvalds 6171da177e4SLinus Torvalds up_write(&_origins_lock); 6181da177e4SLinus Torvalds } 6191da177e4SLinus Torvalds 6201da177e4SLinus Torvalds /* 6211da177e4SLinus Torvalds * Implementation of the exception hash tables. 622d74f81f8SMilan Broz * The lowest hash_shift bits of the chunk number are ignored, allowing 623d74f81f8SMilan Broz * some consecutive chunks to be grouped together. 6241da177e4SLinus Torvalds */ 625f79ae415SNikos Tsironis static uint32_t exception_hash(struct dm_exception_table *et, chunk_t chunk); 626f79ae415SNikos Tsironis 627f79ae415SNikos Tsironis /* Lock to protect access to the completed and pending exception hash tables. */ 628f79ae415SNikos Tsironis struct dm_exception_table_lock { 629f79ae415SNikos Tsironis struct hlist_bl_head *complete_slot; 630f79ae415SNikos Tsironis struct hlist_bl_head *pending_slot; 631f79ae415SNikos Tsironis }; 632f79ae415SNikos Tsironis 633f79ae415SNikos Tsironis static void dm_exception_table_lock_init(struct dm_snapshot *s, chunk_t chunk, 634f79ae415SNikos Tsironis struct dm_exception_table_lock *lock) 635f79ae415SNikos Tsironis { 636f79ae415SNikos Tsironis struct dm_exception_table *complete = &s->complete; 637f79ae415SNikos Tsironis struct dm_exception_table *pending = &s->pending; 638f79ae415SNikos Tsironis 639f79ae415SNikos Tsironis lock->complete_slot = &complete->table[exception_hash(complete, chunk)]; 640f79ae415SNikos Tsironis lock->pending_slot = &pending->table[exception_hash(pending, chunk)]; 641f79ae415SNikos Tsironis } 642f79ae415SNikos Tsironis 643f79ae415SNikos Tsironis static void dm_exception_table_lock(struct dm_exception_table_lock *lock) 644f79ae415SNikos Tsironis { 645f79ae415SNikos Tsironis hlist_bl_lock(lock->complete_slot); 646f79ae415SNikos Tsironis hlist_bl_lock(lock->pending_slot); 647f79ae415SNikos Tsironis } 648f79ae415SNikos Tsironis 649f79ae415SNikos Tsironis static void dm_exception_table_unlock(struct dm_exception_table_lock *lock) 650f79ae415SNikos Tsironis { 651f79ae415SNikos Tsironis hlist_bl_unlock(lock->pending_slot); 652f79ae415SNikos Tsironis hlist_bl_unlock(lock->complete_slot); 653f79ae415SNikos Tsironis } 654f79ae415SNikos Tsironis 6553510cb94SJon Brassow static int dm_exception_table_init(struct dm_exception_table *et, 6563510cb94SJon Brassow uint32_t size, unsigned hash_shift) 6571da177e4SLinus Torvalds { 6581da177e4SLinus Torvalds unsigned int i; 6591da177e4SLinus Torvalds 660d74f81f8SMilan Broz et->hash_shift = hash_shift; 6611da177e4SLinus Torvalds et->hash_mask = size - 1; 662f79ae415SNikos Tsironis et->table = dm_vcalloc(size, sizeof(struct hlist_bl_head)); 6631da177e4SLinus Torvalds if (!et->table) 6641da177e4SLinus Torvalds return -ENOMEM; 6651da177e4SLinus Torvalds 6661da177e4SLinus Torvalds for (i = 0; i < size; i++) 667f79ae415SNikos Tsironis INIT_HLIST_BL_HEAD(et->table + i); 6681da177e4SLinus Torvalds 6691da177e4SLinus Torvalds return 0; 6701da177e4SLinus Torvalds } 6711da177e4SLinus Torvalds 6723510cb94SJon Brassow static void dm_exception_table_exit(struct dm_exception_table *et, 673191437a5SJon Brassow struct kmem_cache *mem) 6741da177e4SLinus Torvalds { 675f79ae415SNikos Tsironis struct hlist_bl_head *slot; 676f79ae415SNikos Tsironis struct dm_exception *ex; 677f79ae415SNikos Tsironis struct hlist_bl_node *pos, *n; 6781da177e4SLinus Torvalds int i, size; 6791da177e4SLinus Torvalds 6801da177e4SLinus Torvalds size = et->hash_mask + 1; 6811da177e4SLinus Torvalds for (i = 0; i < size; i++) { 6821da177e4SLinus Torvalds slot = et->table + i; 6831da177e4SLinus Torvalds 684f79ae415SNikos Tsironis hlist_bl_for_each_entry_safe(ex, pos, n, slot, hash_list) 6851da177e4SLinus Torvalds kmem_cache_free(mem, ex); 6861da177e4SLinus Torvalds } 6871da177e4SLinus Torvalds 6881da177e4SLinus Torvalds vfree(et->table); 6891da177e4SLinus Torvalds } 6901da177e4SLinus Torvalds 691191437a5SJon Brassow static uint32_t exception_hash(struct dm_exception_table *et, chunk_t chunk) 6921da177e4SLinus Torvalds { 693d74f81f8SMilan Broz return (chunk >> et->hash_shift) & et->hash_mask; 6941da177e4SLinus Torvalds } 6951da177e4SLinus Torvalds 6963510cb94SJon Brassow static void dm_remove_exception(struct dm_exception *e) 6971da177e4SLinus Torvalds { 698f79ae415SNikos Tsironis hlist_bl_del(&e->hash_list); 6991da177e4SLinus Torvalds } 7001da177e4SLinus Torvalds 7011da177e4SLinus Torvalds /* 7021da177e4SLinus Torvalds * Return the exception data for a sector, or NULL if not 7031da177e4SLinus Torvalds * remapped. 7041da177e4SLinus Torvalds */ 7053510cb94SJon Brassow static struct dm_exception *dm_lookup_exception(struct dm_exception_table *et, 7061da177e4SLinus Torvalds chunk_t chunk) 7071da177e4SLinus Torvalds { 708f79ae415SNikos Tsironis struct hlist_bl_head *slot; 709f79ae415SNikos Tsironis struct hlist_bl_node *pos; 7101d4989c8SJon Brassow struct dm_exception *e; 7111da177e4SLinus Torvalds 7121da177e4SLinus Torvalds slot = &et->table[exception_hash(et, chunk)]; 713f79ae415SNikos Tsironis hlist_bl_for_each_entry(e, pos, slot, hash_list) 714d74f81f8SMilan Broz if (chunk >= e->old_chunk && 715d74f81f8SMilan Broz chunk <= e->old_chunk + dm_consecutive_chunk_count(e)) 7161da177e4SLinus Torvalds return e; 7171da177e4SLinus Torvalds 7181da177e4SLinus Torvalds return NULL; 7191da177e4SLinus Torvalds } 7201da177e4SLinus Torvalds 721119bc547SMikulas Patocka static struct dm_exception *alloc_completed_exception(gfp_t gfp) 7221da177e4SLinus Torvalds { 7231d4989c8SJon Brassow struct dm_exception *e; 7241da177e4SLinus Torvalds 725119bc547SMikulas Patocka e = kmem_cache_alloc(exception_cache, gfp); 726119bc547SMikulas Patocka if (!e && gfp == GFP_NOIO) 7271da177e4SLinus Torvalds e = kmem_cache_alloc(exception_cache, GFP_ATOMIC); 7281da177e4SLinus Torvalds 7291da177e4SLinus Torvalds return e; 7301da177e4SLinus Torvalds } 7311da177e4SLinus Torvalds 7323510cb94SJon Brassow static void free_completed_exception(struct dm_exception *e) 7331da177e4SLinus Torvalds { 7341da177e4SLinus Torvalds kmem_cache_free(exception_cache, e); 7351da177e4SLinus Torvalds } 7361da177e4SLinus Torvalds 73792e86812SMikulas Patocka static struct dm_snap_pending_exception *alloc_pending_exception(struct dm_snapshot *s) 7381da177e4SLinus Torvalds { 7396f1c819cSKent Overstreet struct dm_snap_pending_exception *pe = mempool_alloc(&s->pending_pool, 74092e86812SMikulas Patocka GFP_NOIO); 74192e86812SMikulas Patocka 742879129d2SMikulas Patocka atomic_inc(&s->pending_exceptions_count); 74392e86812SMikulas Patocka pe->snap = s; 74492e86812SMikulas Patocka 74592e86812SMikulas Patocka return pe; 7461da177e4SLinus Torvalds } 7471da177e4SLinus Torvalds 748028867acSAlasdair G Kergon static void free_pending_exception(struct dm_snap_pending_exception *pe) 7491da177e4SLinus Torvalds { 750879129d2SMikulas Patocka struct dm_snapshot *s = pe->snap; 751879129d2SMikulas Patocka 7526f1c819cSKent Overstreet mempool_free(pe, &s->pending_pool); 7534e857c58SPeter Zijlstra smp_mb__before_atomic(); 754879129d2SMikulas Patocka atomic_dec(&s->pending_exceptions_count); 7551da177e4SLinus Torvalds } 7561da177e4SLinus Torvalds 7573510cb94SJon Brassow static void dm_insert_exception(struct dm_exception_table *eh, 7581d4989c8SJon Brassow struct dm_exception *new_e) 759d74f81f8SMilan Broz { 760f79ae415SNikos Tsironis struct hlist_bl_head *l; 761f79ae415SNikos Tsironis struct hlist_bl_node *pos; 7621d4989c8SJon Brassow struct dm_exception *e = NULL; 763d74f81f8SMilan Broz 764d74f81f8SMilan Broz l = &eh->table[exception_hash(eh, new_e->old_chunk)]; 765d74f81f8SMilan Broz 766d74f81f8SMilan Broz /* Add immediately if this table doesn't support consecutive chunks */ 767d74f81f8SMilan Broz if (!eh->hash_shift) 768d74f81f8SMilan Broz goto out; 769d74f81f8SMilan Broz 770d74f81f8SMilan Broz /* List is ordered by old_chunk */ 771f79ae415SNikos Tsironis hlist_bl_for_each_entry(e, pos, l, hash_list) { 772d74f81f8SMilan Broz /* Insert after an existing chunk? */ 773d74f81f8SMilan Broz if (new_e->old_chunk == (e->old_chunk + 774d74f81f8SMilan Broz dm_consecutive_chunk_count(e) + 1) && 775d74f81f8SMilan Broz new_e->new_chunk == (dm_chunk_number(e->new_chunk) + 776d74f81f8SMilan Broz dm_consecutive_chunk_count(e) + 1)) { 777d74f81f8SMilan Broz dm_consecutive_chunk_count_inc(e); 7783510cb94SJon Brassow free_completed_exception(new_e); 779d74f81f8SMilan Broz return; 780d74f81f8SMilan Broz } 781d74f81f8SMilan Broz 782d74f81f8SMilan Broz /* Insert before an existing chunk? */ 783d74f81f8SMilan Broz if (new_e->old_chunk == (e->old_chunk - 1) && 784d74f81f8SMilan Broz new_e->new_chunk == (dm_chunk_number(e->new_chunk) - 1)) { 785d74f81f8SMilan Broz dm_consecutive_chunk_count_inc(e); 786d74f81f8SMilan Broz e->old_chunk--; 787d74f81f8SMilan Broz e->new_chunk--; 7883510cb94SJon Brassow free_completed_exception(new_e); 789d74f81f8SMilan Broz return; 790d74f81f8SMilan Broz } 791d74f81f8SMilan Broz 792f79ae415SNikos Tsironis if (new_e->old_chunk < e->old_chunk) 793d74f81f8SMilan Broz break; 794d74f81f8SMilan Broz } 795d74f81f8SMilan Broz 796d74f81f8SMilan Broz out: 797f79ae415SNikos Tsironis if (!e) { 798f79ae415SNikos Tsironis /* 799f79ae415SNikos Tsironis * Either the table doesn't support consecutive chunks or slot 800f79ae415SNikos Tsironis * l is empty. 801f79ae415SNikos Tsironis */ 802f79ae415SNikos Tsironis hlist_bl_add_head(&new_e->hash_list, l); 803f79ae415SNikos Tsironis } else if (new_e->old_chunk < e->old_chunk) { 804f79ae415SNikos Tsironis /* Add before an existing exception */ 805f79ae415SNikos Tsironis hlist_bl_add_before(&new_e->hash_list, &e->hash_list); 806f79ae415SNikos Tsironis } else { 807f79ae415SNikos Tsironis /* Add to l's tail: e is the last exception in this slot */ 808f79ae415SNikos Tsironis hlist_bl_add_behind(&new_e->hash_list, &e->hash_list); 809f79ae415SNikos Tsironis } 810d74f81f8SMilan Broz } 811d74f81f8SMilan Broz 812a159c1acSJonathan Brassow /* 813a159c1acSJonathan Brassow * Callback used by the exception stores to load exceptions when 814a159c1acSJonathan Brassow * initialising. 815a159c1acSJonathan Brassow */ 816a159c1acSJonathan Brassow static int dm_add_exception(void *context, chunk_t old, chunk_t new) 8171da177e4SLinus Torvalds { 818f79ae415SNikos Tsironis struct dm_exception_table_lock lock; 819a159c1acSJonathan Brassow struct dm_snapshot *s = context; 8201d4989c8SJon Brassow struct dm_exception *e; 8211da177e4SLinus Torvalds 822119bc547SMikulas Patocka e = alloc_completed_exception(GFP_KERNEL); 8231da177e4SLinus Torvalds if (!e) 8241da177e4SLinus Torvalds return -ENOMEM; 8251da177e4SLinus Torvalds 8261da177e4SLinus Torvalds e->old_chunk = old; 827d74f81f8SMilan Broz 828d74f81f8SMilan Broz /* Consecutive_count is implicitly initialised to zero */ 8291da177e4SLinus Torvalds e->new_chunk = new; 830d74f81f8SMilan Broz 831f79ae415SNikos Tsironis /* 832f79ae415SNikos Tsironis * Although there is no need to lock access to the exception tables 833f79ae415SNikos Tsironis * here, if we don't then hlist_bl_add_head(), called by 834f79ae415SNikos Tsironis * dm_insert_exception(), will complain about accessing the 835f79ae415SNikos Tsironis * corresponding list without locking it first. 836f79ae415SNikos Tsironis */ 837f79ae415SNikos Tsironis dm_exception_table_lock_init(s, old, &lock); 838f79ae415SNikos Tsironis 839f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 8403510cb94SJon Brassow dm_insert_exception(&s->complete, e); 841f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 842d74f81f8SMilan Broz 8431da177e4SLinus Torvalds return 0; 8441da177e4SLinus Torvalds } 8451da177e4SLinus Torvalds 8467e201b35SMikulas Patocka /* 8477e201b35SMikulas Patocka * Return a minimum chunk size of all snapshots that have the specified origin. 8487e201b35SMikulas Patocka * Return zero if the origin has no snapshots. 8497e201b35SMikulas Patocka */ 850542f9038SMike Snitzer static uint32_t __minimum_chunk_size(struct origin *o) 8517e201b35SMikulas Patocka { 8527e201b35SMikulas Patocka struct dm_snapshot *snap; 8537e201b35SMikulas Patocka unsigned chunk_size = 0; 8547e201b35SMikulas Patocka 8557e201b35SMikulas Patocka if (o) 8567e201b35SMikulas Patocka list_for_each_entry(snap, &o->snapshots, list) 8577e201b35SMikulas Patocka chunk_size = min_not_zero(chunk_size, 8587e201b35SMikulas Patocka snap->store->chunk_size); 8597e201b35SMikulas Patocka 860542f9038SMike Snitzer return (uint32_t) chunk_size; 8617e201b35SMikulas Patocka } 8627e201b35SMikulas Patocka 8631da177e4SLinus Torvalds /* 8641da177e4SLinus Torvalds * Hard coded magic. 8651da177e4SLinus Torvalds */ 8661da177e4SLinus Torvalds static int calc_max_buckets(void) 8671da177e4SLinus Torvalds { 8681da177e4SLinus Torvalds /* use a fixed size of 2MB */ 8691da177e4SLinus Torvalds unsigned long mem = 2 * 1024 * 1024; 870f79ae415SNikos Tsironis mem /= sizeof(struct hlist_bl_head); 8711da177e4SLinus Torvalds 8721da177e4SLinus Torvalds return mem; 8731da177e4SLinus Torvalds } 8741da177e4SLinus Torvalds 8751da177e4SLinus Torvalds /* 8761da177e4SLinus Torvalds * Allocate room for a suitable hash table. 8771da177e4SLinus Torvalds */ 878fee1998eSJonathan Brassow static int init_hash_tables(struct dm_snapshot *s) 8791da177e4SLinus Torvalds { 88060e356f3SMikulas Patocka sector_t hash_size, cow_dev_size, max_buckets; 8811da177e4SLinus Torvalds 8821da177e4SLinus Torvalds /* 8831da177e4SLinus Torvalds * Calculate based on the size of the original volume or 8841da177e4SLinus Torvalds * the COW volume... 8851da177e4SLinus Torvalds */ 886fc56f6fbSMike Snitzer cow_dev_size = get_dev_size(s->cow->bdev); 8871da177e4SLinus Torvalds max_buckets = calc_max_buckets(); 8881da177e4SLinus Torvalds 88960e356f3SMikulas Patocka hash_size = cow_dev_size >> s->store->chunk_shift; 8901da177e4SLinus Torvalds hash_size = min(hash_size, max_buckets); 8911da177e4SLinus Torvalds 8928e87b9b8SMikulas Patocka if (hash_size < 64) 8938e87b9b8SMikulas Patocka hash_size = 64; 8948defd830SRobert P. J. Day hash_size = rounddown_pow_of_two(hash_size); 8953510cb94SJon Brassow if (dm_exception_table_init(&s->complete, hash_size, 896d74f81f8SMilan Broz DM_CHUNK_CONSECUTIVE_BITS)) 8971da177e4SLinus Torvalds return -ENOMEM; 8981da177e4SLinus Torvalds 8991da177e4SLinus Torvalds /* 9001da177e4SLinus Torvalds * Allocate hash table for in-flight exceptions 9011da177e4SLinus Torvalds * Make this smaller than the real hash table 9021da177e4SLinus Torvalds */ 9031da177e4SLinus Torvalds hash_size >>= 3; 9041da177e4SLinus Torvalds if (hash_size < 64) 9051da177e4SLinus Torvalds hash_size = 64; 9061da177e4SLinus Torvalds 9073510cb94SJon Brassow if (dm_exception_table_init(&s->pending, hash_size, 0)) { 9083510cb94SJon Brassow dm_exception_table_exit(&s->complete, exception_cache); 9091da177e4SLinus Torvalds return -ENOMEM; 9101da177e4SLinus Torvalds } 9111da177e4SLinus Torvalds 9121da177e4SLinus Torvalds return 0; 9131da177e4SLinus Torvalds } 9141da177e4SLinus Torvalds 9151e03f97eSMikulas Patocka static void merge_shutdown(struct dm_snapshot *s) 9161e03f97eSMikulas Patocka { 9171e03f97eSMikulas Patocka clear_bit_unlock(RUNNING_MERGE, &s->state_bits); 9184e857c58SPeter Zijlstra smp_mb__after_atomic(); 9191e03f97eSMikulas Patocka wake_up_bit(&s->state_bits, RUNNING_MERGE); 9201e03f97eSMikulas Patocka } 9211e03f97eSMikulas Patocka 9229fe86254SMikulas Patocka static struct bio *__release_queued_bios_after_merge(struct dm_snapshot *s) 9239fe86254SMikulas Patocka { 9249fe86254SMikulas Patocka s->first_merging_chunk = 0; 9259fe86254SMikulas Patocka s->num_merging_chunks = 0; 9269fe86254SMikulas Patocka 9279fe86254SMikulas Patocka return bio_list_get(&s->bios_queued_during_merge); 9289fe86254SMikulas Patocka } 9299fe86254SMikulas Patocka 9301e03f97eSMikulas Patocka /* 9311e03f97eSMikulas Patocka * Remove one chunk from the index of completed exceptions. 9321e03f97eSMikulas Patocka */ 9331e03f97eSMikulas Patocka static int __remove_single_exception_chunk(struct dm_snapshot *s, 9341e03f97eSMikulas Patocka chunk_t old_chunk) 9351e03f97eSMikulas Patocka { 9361e03f97eSMikulas Patocka struct dm_exception *e; 9371e03f97eSMikulas Patocka 9381e03f97eSMikulas Patocka e = dm_lookup_exception(&s->complete, old_chunk); 9391e03f97eSMikulas Patocka if (!e) { 9401e03f97eSMikulas Patocka DMERR("Corruption detected: exception for block %llu is " 9411e03f97eSMikulas Patocka "on disk but not in memory", 9421e03f97eSMikulas Patocka (unsigned long long)old_chunk); 9431e03f97eSMikulas Patocka return -EINVAL; 9441e03f97eSMikulas Patocka } 9451e03f97eSMikulas Patocka 9461e03f97eSMikulas Patocka /* 9471e03f97eSMikulas Patocka * If this is the only chunk using this exception, remove exception. 9481e03f97eSMikulas Patocka */ 9491e03f97eSMikulas Patocka if (!dm_consecutive_chunk_count(e)) { 9501e03f97eSMikulas Patocka dm_remove_exception(e); 9511e03f97eSMikulas Patocka free_completed_exception(e); 9521e03f97eSMikulas Patocka return 0; 9531e03f97eSMikulas Patocka } 9541e03f97eSMikulas Patocka 9551e03f97eSMikulas Patocka /* 9561e03f97eSMikulas Patocka * The chunk may be either at the beginning or the end of a 9571e03f97eSMikulas Patocka * group of consecutive chunks - never in the middle. We are 9581e03f97eSMikulas Patocka * removing chunks in the opposite order to that in which they 9591e03f97eSMikulas Patocka * were added, so this should always be true. 9601e03f97eSMikulas Patocka * Decrement the consecutive chunk counter and adjust the 9611e03f97eSMikulas Patocka * starting point if necessary. 9621e03f97eSMikulas Patocka */ 9631e03f97eSMikulas Patocka if (old_chunk == e->old_chunk) { 9641e03f97eSMikulas Patocka e->old_chunk++; 9651e03f97eSMikulas Patocka e->new_chunk++; 9661e03f97eSMikulas Patocka } else if (old_chunk != e->old_chunk + 9671e03f97eSMikulas Patocka dm_consecutive_chunk_count(e)) { 9681e03f97eSMikulas Patocka DMERR("Attempt to merge block %llu from the " 9691e03f97eSMikulas Patocka "middle of a chunk range [%llu - %llu]", 9701e03f97eSMikulas Patocka (unsigned long long)old_chunk, 9711e03f97eSMikulas Patocka (unsigned long long)e->old_chunk, 9721e03f97eSMikulas Patocka (unsigned long long) 9731e03f97eSMikulas Patocka e->old_chunk + dm_consecutive_chunk_count(e)); 9741e03f97eSMikulas Patocka return -EINVAL; 9751e03f97eSMikulas Patocka } 9761e03f97eSMikulas Patocka 9771e03f97eSMikulas Patocka dm_consecutive_chunk_count_dec(e); 9781e03f97eSMikulas Patocka 9791e03f97eSMikulas Patocka return 0; 9801e03f97eSMikulas Patocka } 9811e03f97eSMikulas Patocka 9829fe86254SMikulas Patocka static void flush_bios(struct bio *bio); 9839fe86254SMikulas Patocka 9849fe86254SMikulas Patocka static int remove_single_exception_chunk(struct dm_snapshot *s) 9851e03f97eSMikulas Patocka { 9869fe86254SMikulas Patocka struct bio *b = NULL; 9879fe86254SMikulas Patocka int r; 9889fe86254SMikulas Patocka chunk_t old_chunk = s->first_merging_chunk + s->num_merging_chunks - 1; 9891e03f97eSMikulas Patocka 9904ad8d880SNikos Tsironis down_write(&s->lock); 9919fe86254SMikulas Patocka 9929fe86254SMikulas Patocka /* 9939fe86254SMikulas Patocka * Process chunks (and associated exceptions) in reverse order 9949fe86254SMikulas Patocka * so that dm_consecutive_chunk_count_dec() accounting works. 9959fe86254SMikulas Patocka */ 9969fe86254SMikulas Patocka do { 9971e03f97eSMikulas Patocka r = __remove_single_exception_chunk(s, old_chunk); 9989fe86254SMikulas Patocka if (r) 9999fe86254SMikulas Patocka goto out; 10009fe86254SMikulas Patocka } while (old_chunk-- > s->first_merging_chunk); 10019fe86254SMikulas Patocka 10029fe86254SMikulas Patocka b = __release_queued_bios_after_merge(s); 10039fe86254SMikulas Patocka 10049fe86254SMikulas Patocka out: 10054ad8d880SNikos Tsironis up_write(&s->lock); 10069fe86254SMikulas Patocka if (b) 10079fe86254SMikulas Patocka flush_bios(b); 10081e03f97eSMikulas Patocka 10091e03f97eSMikulas Patocka return r; 10101e03f97eSMikulas Patocka } 10111e03f97eSMikulas Patocka 101273dfd078SMikulas Patocka static int origin_write_extent(struct dm_snapshot *merging_snap, 101373dfd078SMikulas Patocka sector_t sector, unsigned chunk_size); 101473dfd078SMikulas Patocka 10151e03f97eSMikulas Patocka static void merge_callback(int read_err, unsigned long write_err, 10161e03f97eSMikulas Patocka void *context); 10171e03f97eSMikulas Patocka 101873dfd078SMikulas Patocka static uint64_t read_pending_exceptions_done_count(void) 101973dfd078SMikulas Patocka { 102073dfd078SMikulas Patocka uint64_t pending_exceptions_done; 102173dfd078SMikulas Patocka 102273dfd078SMikulas Patocka spin_lock(&_pending_exceptions_done_spinlock); 102373dfd078SMikulas Patocka pending_exceptions_done = _pending_exceptions_done_count; 102473dfd078SMikulas Patocka spin_unlock(&_pending_exceptions_done_spinlock); 102573dfd078SMikulas Patocka 102673dfd078SMikulas Patocka return pending_exceptions_done; 102773dfd078SMikulas Patocka } 102873dfd078SMikulas Patocka 102973dfd078SMikulas Patocka static void increment_pending_exceptions_done_count(void) 103073dfd078SMikulas Patocka { 103173dfd078SMikulas Patocka spin_lock(&_pending_exceptions_done_spinlock); 103273dfd078SMikulas Patocka _pending_exceptions_done_count++; 103373dfd078SMikulas Patocka spin_unlock(&_pending_exceptions_done_spinlock); 103473dfd078SMikulas Patocka 103573dfd078SMikulas Patocka wake_up_all(&_pending_exceptions_done); 103673dfd078SMikulas Patocka } 103773dfd078SMikulas Patocka 10381e03f97eSMikulas Patocka static void snapshot_merge_next_chunks(struct dm_snapshot *s) 10391e03f97eSMikulas Patocka { 10408a2d5286SMike Snitzer int i, linear_chunks; 10411e03f97eSMikulas Patocka chunk_t old_chunk, new_chunk; 10421e03f97eSMikulas Patocka struct dm_io_region src, dest; 10438a2d5286SMike Snitzer sector_t io_size; 104473dfd078SMikulas Patocka uint64_t previous_count; 10451e03f97eSMikulas Patocka 10461e03f97eSMikulas Patocka BUG_ON(!test_bit(RUNNING_MERGE, &s->state_bits)); 10471e03f97eSMikulas Patocka if (unlikely(test_bit(SHUTDOWN_MERGE, &s->state_bits))) 10481e03f97eSMikulas Patocka goto shut; 10491e03f97eSMikulas Patocka 10501e03f97eSMikulas Patocka /* 10511e03f97eSMikulas Patocka * valid flag never changes during merge, so no lock required. 10521e03f97eSMikulas Patocka */ 10531e03f97eSMikulas Patocka if (!s->valid) { 10541e03f97eSMikulas Patocka DMERR("Snapshot is invalid: can't merge"); 10551e03f97eSMikulas Patocka goto shut; 10561e03f97eSMikulas Patocka } 10571e03f97eSMikulas Patocka 10588a2d5286SMike Snitzer linear_chunks = s->store->type->prepare_merge(s->store, &old_chunk, 10598a2d5286SMike Snitzer &new_chunk); 10608a2d5286SMike Snitzer if (linear_chunks <= 0) { 1061d8ddb1cfSMike Snitzer if (linear_chunks < 0) { 10621e03f97eSMikulas Patocka DMERR("Read error in exception store: " 10631e03f97eSMikulas Patocka "shutting down merge"); 10644ad8d880SNikos Tsironis down_write(&s->lock); 1065d8ddb1cfSMike Snitzer s->merge_failed = 1; 10664ad8d880SNikos Tsironis up_write(&s->lock); 1067d8ddb1cfSMike Snitzer } 10681e03f97eSMikulas Patocka goto shut; 10691e03f97eSMikulas Patocka } 10701e03f97eSMikulas Patocka 10718a2d5286SMike Snitzer /* Adjust old_chunk and new_chunk to reflect start of linear region */ 10728a2d5286SMike Snitzer old_chunk = old_chunk + 1 - linear_chunks; 10738a2d5286SMike Snitzer new_chunk = new_chunk + 1 - linear_chunks; 10748a2d5286SMike Snitzer 10758a2d5286SMike Snitzer /* 10768a2d5286SMike Snitzer * Use one (potentially large) I/O to copy all 'linear_chunks' 10778a2d5286SMike Snitzer * from the exception store to the origin 10788a2d5286SMike Snitzer */ 10798a2d5286SMike Snitzer io_size = linear_chunks * s->store->chunk_size; 10801e03f97eSMikulas Patocka 10811e03f97eSMikulas Patocka dest.bdev = s->origin->bdev; 10821e03f97eSMikulas Patocka dest.sector = chunk_to_sector(s->store, old_chunk); 10838a2d5286SMike Snitzer dest.count = min(io_size, get_dev_size(dest.bdev) - dest.sector); 10841e03f97eSMikulas Patocka 10851e03f97eSMikulas Patocka src.bdev = s->cow->bdev; 10861e03f97eSMikulas Patocka src.sector = chunk_to_sector(s->store, new_chunk); 10871e03f97eSMikulas Patocka src.count = dest.count; 10881e03f97eSMikulas Patocka 108973dfd078SMikulas Patocka /* 109073dfd078SMikulas Patocka * Reallocate any exceptions needed in other snapshots then 109173dfd078SMikulas Patocka * wait for the pending exceptions to complete. 109273dfd078SMikulas Patocka * Each time any pending exception (globally on the system) 109373dfd078SMikulas Patocka * completes we are woken and repeat the process to find out 109473dfd078SMikulas Patocka * if we can proceed. While this may not seem a particularly 109573dfd078SMikulas Patocka * efficient algorithm, it is not expected to have any 109673dfd078SMikulas Patocka * significant impact on performance. 109773dfd078SMikulas Patocka */ 109873dfd078SMikulas Patocka previous_count = read_pending_exceptions_done_count(); 10998a2d5286SMike Snitzer while (origin_write_extent(s, dest.sector, io_size)) { 110073dfd078SMikulas Patocka wait_event(_pending_exceptions_done, 110173dfd078SMikulas Patocka (read_pending_exceptions_done_count() != 110273dfd078SMikulas Patocka previous_count)); 110373dfd078SMikulas Patocka /* Retry after the wait, until all exceptions are done. */ 110473dfd078SMikulas Patocka previous_count = read_pending_exceptions_done_count(); 110573dfd078SMikulas Patocka } 110673dfd078SMikulas Patocka 11074ad8d880SNikos Tsironis down_write(&s->lock); 11089fe86254SMikulas Patocka s->first_merging_chunk = old_chunk; 11098a2d5286SMike Snitzer s->num_merging_chunks = linear_chunks; 11104ad8d880SNikos Tsironis up_write(&s->lock); 11119fe86254SMikulas Patocka 11128a2d5286SMike Snitzer /* Wait until writes to all 'linear_chunks' drain */ 11138a2d5286SMike Snitzer for (i = 0; i < linear_chunks; i++) 11148a2d5286SMike Snitzer __check_for_conflicting_io(s, old_chunk + i); 11159fe86254SMikulas Patocka 11161e03f97eSMikulas Patocka dm_kcopyd_copy(s->kcopyd_client, &src, 1, &dest, 0, merge_callback, s); 11171e03f97eSMikulas Patocka return; 11181e03f97eSMikulas Patocka 11191e03f97eSMikulas Patocka shut: 11201e03f97eSMikulas Patocka merge_shutdown(s); 11211e03f97eSMikulas Patocka } 11221e03f97eSMikulas Patocka 11239fe86254SMikulas Patocka static void error_bios(struct bio *bio); 11249fe86254SMikulas Patocka 11251e03f97eSMikulas Patocka static void merge_callback(int read_err, unsigned long write_err, void *context) 11261e03f97eSMikulas Patocka { 11271e03f97eSMikulas Patocka struct dm_snapshot *s = context; 11289fe86254SMikulas Patocka struct bio *b = NULL; 11291e03f97eSMikulas Patocka 11301e03f97eSMikulas Patocka if (read_err || write_err) { 11311e03f97eSMikulas Patocka if (read_err) 11321e03f97eSMikulas Patocka DMERR("Read error: shutting down merge."); 11331e03f97eSMikulas Patocka else 11341e03f97eSMikulas Patocka DMERR("Write error: shutting down merge."); 11351e03f97eSMikulas Patocka goto shut; 11361e03f97eSMikulas Patocka } 11371e03f97eSMikulas Patocka 11389fe86254SMikulas Patocka if (s->store->type->commit_merge(s->store, 11399fe86254SMikulas Patocka s->num_merging_chunks) < 0) { 11401e03f97eSMikulas Patocka DMERR("Write error in exception store: shutting down merge"); 11411e03f97eSMikulas Patocka goto shut; 11421e03f97eSMikulas Patocka } 11431e03f97eSMikulas Patocka 11449fe86254SMikulas Patocka if (remove_single_exception_chunk(s) < 0) 11459fe86254SMikulas Patocka goto shut; 11469fe86254SMikulas Patocka 11471e03f97eSMikulas Patocka snapshot_merge_next_chunks(s); 11481e03f97eSMikulas Patocka 11491e03f97eSMikulas Patocka return; 11501e03f97eSMikulas Patocka 11511e03f97eSMikulas Patocka shut: 11524ad8d880SNikos Tsironis down_write(&s->lock); 1153d8ddb1cfSMike Snitzer s->merge_failed = 1; 11549fe86254SMikulas Patocka b = __release_queued_bios_after_merge(s); 11554ad8d880SNikos Tsironis up_write(&s->lock); 11569fe86254SMikulas Patocka error_bios(b); 11579fe86254SMikulas Patocka 11581e03f97eSMikulas Patocka merge_shutdown(s); 11591e03f97eSMikulas Patocka } 11601e03f97eSMikulas Patocka 11611e03f97eSMikulas Patocka static void start_merge(struct dm_snapshot *s) 11621e03f97eSMikulas Patocka { 11631e03f97eSMikulas Patocka if (!test_and_set_bit(RUNNING_MERGE, &s->state_bits)) 11641e03f97eSMikulas Patocka snapshot_merge_next_chunks(s); 11651e03f97eSMikulas Patocka } 11661e03f97eSMikulas Patocka 11671e03f97eSMikulas Patocka /* 11681e03f97eSMikulas Patocka * Stop the merging process and wait until it finishes. 11691e03f97eSMikulas Patocka */ 11701e03f97eSMikulas Patocka static void stop_merge(struct dm_snapshot *s) 11711e03f97eSMikulas Patocka { 11721e03f97eSMikulas Patocka set_bit(SHUTDOWN_MERGE, &s->state_bits); 117374316201SNeilBrown wait_on_bit(&s->state_bits, RUNNING_MERGE, TASK_UNINTERRUPTIBLE); 11741e03f97eSMikulas Patocka clear_bit(SHUTDOWN_MERGE, &s->state_bits); 11751e03f97eSMikulas Patocka } 11761e03f97eSMikulas Patocka 11772e602385SMike Snitzer static int parse_snapshot_features(struct dm_arg_set *as, struct dm_snapshot *s, 11782e602385SMike Snitzer struct dm_target *ti) 11792e602385SMike Snitzer { 11802e602385SMike Snitzer int r; 11812e602385SMike Snitzer unsigned argc; 11822e602385SMike Snitzer const char *arg_name; 11832e602385SMike Snitzer 11842e602385SMike Snitzer static const struct dm_arg _args[] = { 11852e602385SMike Snitzer {0, 2, "Invalid number of feature arguments"}, 11862e602385SMike Snitzer }; 11872e602385SMike Snitzer 11881da177e4SLinus Torvalds /* 11892e602385SMike Snitzer * No feature arguments supplied. 11902e602385SMike Snitzer */ 11912e602385SMike Snitzer if (!as->argc) 11922e602385SMike Snitzer return 0; 11932e602385SMike Snitzer 11942e602385SMike Snitzer r = dm_read_arg_group(_args, as, &argc, &ti->error); 11952e602385SMike Snitzer if (r) 11962e602385SMike Snitzer return -EINVAL; 11972e602385SMike Snitzer 11982e602385SMike Snitzer while (argc && !r) { 11992e602385SMike Snitzer arg_name = dm_shift_arg(as); 12002e602385SMike Snitzer argc--; 12012e602385SMike Snitzer 12022e602385SMike Snitzer if (!strcasecmp(arg_name, "discard_zeroes_cow")) 12032e602385SMike Snitzer s->discard_zeroes_cow = true; 12042e602385SMike Snitzer 12052e602385SMike Snitzer else if (!strcasecmp(arg_name, "discard_passdown_origin")) 12062e602385SMike Snitzer s->discard_passdown_origin = true; 12072e602385SMike Snitzer 12082e602385SMike Snitzer else { 12092e602385SMike Snitzer ti->error = "Unrecognised feature requested"; 12102e602385SMike Snitzer r = -EINVAL; 12112e602385SMike Snitzer break; 12122e602385SMike Snitzer } 12132e602385SMike Snitzer } 12142e602385SMike Snitzer 12152e602385SMike Snitzer if (!s->discard_zeroes_cow && s->discard_passdown_origin) { 12162e602385SMike Snitzer /* 12172e602385SMike Snitzer * TODO: really these are disjoint.. but ti->num_discard_bios 12182e602385SMike Snitzer * and dm_bio_get_target_bio_nr() require rigid constraints. 12192e602385SMike Snitzer */ 12202e602385SMike Snitzer ti->error = "discard_passdown_origin feature depends on discard_zeroes_cow"; 12212e602385SMike Snitzer r = -EINVAL; 12222e602385SMike Snitzer } 12232e602385SMike Snitzer 12242e602385SMike Snitzer return r; 12252e602385SMike Snitzer } 12262e602385SMike Snitzer 12272e602385SMike Snitzer /* 12282e602385SMike Snitzer * Construct a snapshot mapping: 12292e602385SMike Snitzer * <origin_dev> <COW-dev> <p|po|n> <chunk-size> [<# feature args> [<arg>]*] 12301da177e4SLinus Torvalds */ 12311da177e4SLinus Torvalds static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv) 12321da177e4SLinus Torvalds { 12331da177e4SLinus Torvalds struct dm_snapshot *s; 12342e602385SMike Snitzer struct dm_arg_set as; 1235cd45daffSMikulas Patocka int i; 12361da177e4SLinus Torvalds int r = -EINVAL; 1237fc56f6fbSMike Snitzer char *origin_path, *cow_path; 12384df2bf46SDingXiang dev_t origin_dev, cow_dev; 123955a62eefSAlasdair G Kergon unsigned args_used, num_flush_bios = 1; 124010b8106aSMike Snitzer fmode_t origin_mode = FMODE_READ; 12411da177e4SLinus Torvalds 12422e602385SMike Snitzer if (argc < 4) { 12432e602385SMike Snitzer ti->error = "requires 4 or more arguments"; 12441da177e4SLinus Torvalds r = -EINVAL; 1245fc56f6fbSMike Snitzer goto bad; 12461da177e4SLinus Torvalds } 12471da177e4SLinus Torvalds 124810b8106aSMike Snitzer if (dm_target_is_snapshot_merge(ti)) { 124955a62eefSAlasdair G Kergon num_flush_bios = 2; 125010b8106aSMike Snitzer origin_mode = FMODE_WRITE; 125110b8106aSMike Snitzer } 125210b8106aSMike Snitzer 1253d3775354SKent Overstreet s = kzalloc(sizeof(*s), GFP_KERNEL); 1254fee1998eSJonathan Brassow if (!s) { 1255a2d2b034SJonathan Brassow ti->error = "Cannot allocate private snapshot structure"; 12561da177e4SLinus Torvalds r = -ENOMEM; 1257fc56f6fbSMike Snitzer goto bad; 12581da177e4SLinus Torvalds } 12591da177e4SLinus Torvalds 12602e602385SMike Snitzer as.argc = argc; 12612e602385SMike Snitzer as.argv = argv; 12622e602385SMike Snitzer dm_consume_args(&as, 4); 12632e602385SMike Snitzer r = parse_snapshot_features(&as, s, ti); 12642e602385SMike Snitzer if (r) 12652e602385SMike Snitzer goto bad_features; 12662e602385SMike Snitzer 1267c2411045SMikulas Patocka origin_path = argv[0]; 1268c2411045SMikulas Patocka argv++; 1269c2411045SMikulas Patocka argc--; 1270c2411045SMikulas Patocka 1271c2411045SMikulas Patocka r = dm_get_device(ti, origin_path, origin_mode, &s->origin); 1272c2411045SMikulas Patocka if (r) { 1273c2411045SMikulas Patocka ti->error = "Cannot get origin device"; 1274c2411045SMikulas Patocka goto bad_origin; 1275c2411045SMikulas Patocka } 12764df2bf46SDingXiang origin_dev = s->origin->bdev->bd_dev; 1277c2411045SMikulas Patocka 1278fc56f6fbSMike Snitzer cow_path = argv[0]; 1279fc56f6fbSMike Snitzer argv++; 1280fc56f6fbSMike Snitzer argc--; 1281fc56f6fbSMike Snitzer 12824df2bf46SDingXiang cow_dev = dm_get_dev_t(cow_path); 12834df2bf46SDingXiang if (cow_dev && cow_dev == origin_dev) { 12844df2bf46SDingXiang ti->error = "COW device cannot be the same as origin device"; 12854df2bf46SDingXiang r = -EINVAL; 12864df2bf46SDingXiang goto bad_cow; 12874df2bf46SDingXiang } 12884df2bf46SDingXiang 1289024d37e9SMilan Broz r = dm_get_device(ti, cow_path, dm_table_get_mode(ti->table), &s->cow); 1290fc56f6fbSMike Snitzer if (r) { 1291fc56f6fbSMike Snitzer ti->error = "Cannot get COW device"; 1292fc56f6fbSMike Snitzer goto bad_cow; 1293fc56f6fbSMike Snitzer } 1294fc56f6fbSMike Snitzer 1295fc56f6fbSMike Snitzer r = dm_exception_store_create(ti, argc, argv, s, &args_used, &s->store); 1296fc56f6fbSMike Snitzer if (r) { 1297fc56f6fbSMike Snitzer ti->error = "Couldn't create exception store"; 1298fc56f6fbSMike Snitzer r = -EINVAL; 1299fc56f6fbSMike Snitzer goto bad_store; 1300fc56f6fbSMike Snitzer } 1301fc56f6fbSMike Snitzer 1302fc56f6fbSMike Snitzer argv += args_used; 1303fc56f6fbSMike Snitzer argc -= args_used; 1304fc56f6fbSMike Snitzer 1305fc56f6fbSMike Snitzer s->ti = ti; 13061da177e4SLinus Torvalds s->valid = 1; 130776c44f6dSMikulas Patocka s->snapshot_overflowed = 0; 1308aa14edebSAlasdair G Kergon s->active = 0; 1309879129d2SMikulas Patocka atomic_set(&s->pending_exceptions_count, 0); 13103f1637f2SNikos Tsironis spin_lock_init(&s->pe_allocation_lock); 1311230c83afSMikulas Patocka s->exception_start_sequence = 0; 1312230c83afSMikulas Patocka s->exception_complete_sequence = 0; 13133db2776dSDavid Jeffery s->out_of_order_tree = RB_ROOT; 13144ad8d880SNikos Tsironis init_rwsem(&s->lock); 1315c1f0c183SMike Snitzer INIT_LIST_HEAD(&s->list); 1316ca3a931fSAlasdair G Kergon spin_lock_init(&s->pe_lock); 13171e03f97eSMikulas Patocka s->state_bits = 0; 1318d8ddb1cfSMike Snitzer s->merge_failed = 0; 13199fe86254SMikulas Patocka s->first_merging_chunk = 0; 13209fe86254SMikulas Patocka s->num_merging_chunks = 0; 13219fe86254SMikulas Patocka bio_list_init(&s->bios_queued_during_merge); 13221da177e4SLinus Torvalds 13231da177e4SLinus Torvalds /* Allocate hash table for COW data */ 1324fee1998eSJonathan Brassow if (init_hash_tables(s)) { 13251da177e4SLinus Torvalds ti->error = "Unable to allocate hash table space"; 13261da177e4SLinus Torvalds r = -ENOMEM; 1327fee1998eSJonathan Brassow goto bad_hash_tables; 13281da177e4SLinus Torvalds } 13291da177e4SLinus Torvalds 1330721b1d98SNikos Tsironis sema_init(&s->cow_count, (cow_threshold > 0) ? cow_threshold : INT_MAX); 1331721b1d98SNikos Tsironis 1332df5d2e90SMikulas Patocka s->kcopyd_client = dm_kcopyd_client_create(&dm_kcopyd_throttle); 1333fa34ce73SMikulas Patocka if (IS_ERR(s->kcopyd_client)) { 1334fa34ce73SMikulas Patocka r = PTR_ERR(s->kcopyd_client); 13351da177e4SLinus Torvalds ti->error = "Could not create kcopyd client"; 1336fee1998eSJonathan Brassow goto bad_kcopyd; 13371da177e4SLinus Torvalds } 13381da177e4SLinus Torvalds 13396f1c819cSKent Overstreet r = mempool_init_slab_pool(&s->pending_pool, MIN_IOS, pending_cache); 13406f1c819cSKent Overstreet if (r) { 134192e86812SMikulas Patocka ti->error = "Could not allocate mempool for pending exceptions"; 1342fee1998eSJonathan Brassow goto bad_pending_pool; 134392e86812SMikulas Patocka } 134492e86812SMikulas Patocka 1345cd45daffSMikulas Patocka for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) 1346cd45daffSMikulas Patocka INIT_HLIST_HEAD(&s->tracked_chunk_hash[i]); 1347cd45daffSMikulas Patocka 1348cd45daffSMikulas Patocka spin_lock_init(&s->tracked_chunk_lock); 1349cd45daffSMikulas Patocka 1350c1f0c183SMike Snitzer ti->private = s; 135155a62eefSAlasdair G Kergon ti->num_flush_bios = num_flush_bios; 13522e602385SMike Snitzer if (s->discard_zeroes_cow) 13532e602385SMike Snitzer ti->num_discard_bios = (s->discard_passdown_origin ? 2 : 1); 135430187e1dSMike Snitzer ti->per_io_data_size = sizeof(struct dm_snap_tracked_chunk); 1355c1f0c183SMike Snitzer 1356c1f0c183SMike Snitzer /* Add snapshot to the list of snapshots for this origin */ 1357c1f0c183SMike Snitzer /* Exceptions aren't triggered till snapshot_resume() is called */ 1358c1f0c183SMike Snitzer r = register_snapshot(s); 1359c1f0c183SMike Snitzer if (r == -ENOMEM) { 1360c1f0c183SMike Snitzer ti->error = "Snapshot origin struct allocation failed"; 1361c1f0c183SMike Snitzer goto bad_load_and_register; 1362c1f0c183SMike Snitzer } else if (r < 0) { 1363c1f0c183SMike Snitzer /* invalid handover, register_snapshot has set ti->error */ 1364c1f0c183SMike Snitzer goto bad_load_and_register; 1365c1f0c183SMike Snitzer } 1366c1f0c183SMike Snitzer 1367c1f0c183SMike Snitzer /* 1368c1f0c183SMike Snitzer * Metadata must only be loaded into one table at once, so skip this 1369c1f0c183SMike Snitzer * if metadata will be handed over during resume. 1370c1f0c183SMike Snitzer * Chunk size will be set during the handover - set it to zero to 1371c1f0c183SMike Snitzer * ensure it's ignored. 1372c1f0c183SMike Snitzer */ 1373c1f0c183SMike Snitzer if (r > 0) { 1374c1f0c183SMike Snitzer s->store->chunk_size = 0; 1375c1f0c183SMike Snitzer return 0; 1376c1f0c183SMike Snitzer } 1377c1f0c183SMike Snitzer 1378493df71cSJonathan Brassow r = s->store->type->read_metadata(s->store, dm_add_exception, 1379493df71cSJonathan Brassow (void *)s); 13800764147bSMilan Broz if (r < 0) { 1381f9cea4f7SMark McLoughlin ti->error = "Failed to read snapshot metadata"; 1382c1f0c183SMike Snitzer goto bad_read_metadata; 13830764147bSMilan Broz } else if (r > 0) { 13840764147bSMilan Broz s->valid = 0; 13850764147bSMilan Broz DMWARN("Snapshot is marked invalid."); 1386f9cea4f7SMark McLoughlin } 1387aa14edebSAlasdair G Kergon 13883f2412dcSMikulas Patocka if (!s->store->chunk_size) { 13893f2412dcSMikulas Patocka ti->error = "Chunk size not set"; 1390c1f0c183SMike Snitzer goto bad_read_metadata; 13913f2412dcSMikulas Patocka } 1392542f9038SMike Snitzer 1393542f9038SMike Snitzer r = dm_set_target_max_io_len(ti, s->store->chunk_size); 1394542f9038SMike Snitzer if (r) 1395542f9038SMike Snitzer goto bad_read_metadata; 13961da177e4SLinus Torvalds 13971da177e4SLinus Torvalds return 0; 13981da177e4SLinus Torvalds 1399c1f0c183SMike Snitzer bad_read_metadata: 1400c1f0c183SMike Snitzer unregister_snapshot(s); 1401cd45daffSMikulas Patocka bad_load_and_register: 14026f1c819cSKent Overstreet mempool_exit(&s->pending_pool); 1403fee1998eSJonathan Brassow bad_pending_pool: 1404eb69aca5SHeinz Mauelshagen dm_kcopyd_client_destroy(s->kcopyd_client); 1405fee1998eSJonathan Brassow bad_kcopyd: 14063510cb94SJon Brassow dm_exception_table_exit(&s->pending, pending_cache); 14073510cb94SJon Brassow dm_exception_table_exit(&s->complete, exception_cache); 1408fee1998eSJonathan Brassow bad_hash_tables: 1409fc56f6fbSMike Snitzer dm_exception_store_destroy(s->store); 1410fc56f6fbSMike Snitzer bad_store: 1411fc56f6fbSMike Snitzer dm_put_device(ti, s->cow); 1412fc56f6fbSMike Snitzer bad_cow: 1413c2411045SMikulas Patocka dm_put_device(ti, s->origin); 1414c2411045SMikulas Patocka bad_origin: 14152e602385SMike Snitzer bad_features: 14161da177e4SLinus Torvalds kfree(s); 1417fc56f6fbSMike Snitzer bad: 14181da177e4SLinus Torvalds return r; 14191da177e4SLinus Torvalds } 14201da177e4SLinus Torvalds 142131c93a0cSMilan Broz static void __free_exceptions(struct dm_snapshot *s) 142231c93a0cSMilan Broz { 1423eb69aca5SHeinz Mauelshagen dm_kcopyd_client_destroy(s->kcopyd_client); 142431c93a0cSMilan Broz s->kcopyd_client = NULL; 142531c93a0cSMilan Broz 14263510cb94SJon Brassow dm_exception_table_exit(&s->pending, pending_cache); 14273510cb94SJon Brassow dm_exception_table_exit(&s->complete, exception_cache); 142831c93a0cSMilan Broz } 142931c93a0cSMilan Broz 1430c1f0c183SMike Snitzer static void __handover_exceptions(struct dm_snapshot *snap_src, 1431c1f0c183SMike Snitzer struct dm_snapshot *snap_dest) 1432c1f0c183SMike Snitzer { 1433c1f0c183SMike Snitzer union { 1434c1f0c183SMike Snitzer struct dm_exception_table table_swap; 1435c1f0c183SMike Snitzer struct dm_exception_store *store_swap; 1436c1f0c183SMike Snitzer } u; 1437c1f0c183SMike Snitzer 1438c1f0c183SMike Snitzer /* 1439c1f0c183SMike Snitzer * Swap all snapshot context information between the two instances. 1440c1f0c183SMike Snitzer */ 1441c1f0c183SMike Snitzer u.table_swap = snap_dest->complete; 1442c1f0c183SMike Snitzer snap_dest->complete = snap_src->complete; 1443c1f0c183SMike Snitzer snap_src->complete = u.table_swap; 1444c1f0c183SMike Snitzer 1445c1f0c183SMike Snitzer u.store_swap = snap_dest->store; 1446c1f0c183SMike Snitzer snap_dest->store = snap_src->store; 1447b0d3cc01SMike Snitzer snap_dest->store->userspace_supports_overflow = u.store_swap->userspace_supports_overflow; 1448c1f0c183SMike Snitzer snap_src->store = u.store_swap; 1449c1f0c183SMike Snitzer 1450c1f0c183SMike Snitzer snap_dest->store->snap = snap_dest; 1451c1f0c183SMike Snitzer snap_src->store->snap = snap_src; 1452c1f0c183SMike Snitzer 1453542f9038SMike Snitzer snap_dest->ti->max_io_len = snap_dest->store->chunk_size; 1454c1f0c183SMike Snitzer snap_dest->valid = snap_src->valid; 145576c44f6dSMikulas Patocka snap_dest->snapshot_overflowed = snap_src->snapshot_overflowed; 1456c1f0c183SMike Snitzer 1457c1f0c183SMike Snitzer /* 1458c1f0c183SMike Snitzer * Set source invalid to ensure it receives no further I/O. 1459c1f0c183SMike Snitzer */ 1460c1f0c183SMike Snitzer snap_src->valid = 0; 1461c1f0c183SMike Snitzer } 1462c1f0c183SMike Snitzer 14631da177e4SLinus Torvalds static void snapshot_dtr(struct dm_target *ti) 14641da177e4SLinus Torvalds { 1465cd45daffSMikulas Patocka #ifdef CONFIG_DM_DEBUG 1466cd45daffSMikulas Patocka int i; 1467cd45daffSMikulas Patocka #endif 1468028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 1469c1f0c183SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 14701da177e4SLinus Torvalds 1471c1f0c183SMike Snitzer down_read(&_origins_lock); 1472c1f0c183SMike Snitzer /* Check whether exception handover must be cancelled */ 14739d3b15c4SMikulas Patocka (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); 1474c1f0c183SMike Snitzer if (snap_src && snap_dest && (s == snap_src)) { 14754ad8d880SNikos Tsironis down_write(&snap_dest->lock); 1476c1f0c183SMike Snitzer snap_dest->valid = 0; 14774ad8d880SNikos Tsironis up_write(&snap_dest->lock); 1478c1f0c183SMike Snitzer DMERR("Cancelling snapshot handover."); 1479c1f0c183SMike Snitzer } 1480c1f0c183SMike Snitzer up_read(&_origins_lock); 1481c1f0c183SMike Snitzer 14821e03f97eSMikulas Patocka if (dm_target_is_snapshot_merge(ti)) 14831e03f97eSMikulas Patocka stop_merge(s); 14841e03f97eSMikulas Patocka 1485138728dcSAlasdair G Kergon /* Prevent further origin writes from using this snapshot. */ 1486138728dcSAlasdair G Kergon /* After this returns there can be no new kcopyd jobs. */ 14871da177e4SLinus Torvalds unregister_snapshot(s); 14881da177e4SLinus Torvalds 1489879129d2SMikulas Patocka while (atomic_read(&s->pending_exceptions_count)) 149090fa1527SMikulas Patocka msleep(1); 1491879129d2SMikulas Patocka /* 14926f1c819cSKent Overstreet * Ensure instructions in mempool_exit aren't reordered 1493879129d2SMikulas Patocka * before atomic_read. 1494879129d2SMikulas Patocka */ 1495879129d2SMikulas Patocka smp_mb(); 1496879129d2SMikulas Patocka 1497cd45daffSMikulas Patocka #ifdef CONFIG_DM_DEBUG 1498cd45daffSMikulas Patocka for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) 1499cd45daffSMikulas Patocka BUG_ON(!hlist_empty(&s->tracked_chunk_hash[i])); 1500cd45daffSMikulas Patocka #endif 1501cd45daffSMikulas Patocka 150231c93a0cSMilan Broz __free_exceptions(s); 15031da177e4SLinus Torvalds 15046f1c819cSKent Overstreet mempool_exit(&s->pending_pool); 150592e86812SMikulas Patocka 1506fee1998eSJonathan Brassow dm_exception_store_destroy(s->store); 1507138728dcSAlasdair G Kergon 1508fc56f6fbSMike Snitzer dm_put_device(ti, s->cow); 1509fc56f6fbSMike Snitzer 1510c2411045SMikulas Patocka dm_put_device(ti, s->origin); 1511c2411045SMikulas Patocka 15121da177e4SLinus Torvalds kfree(s); 15131da177e4SLinus Torvalds } 15141da177e4SLinus Torvalds 1515a2f83e8bSMikulas Patocka static void account_start_copy(struct dm_snapshot *s) 1516a2f83e8bSMikulas Patocka { 1517a2f83e8bSMikulas Patocka down(&s->cow_count); 1518a2f83e8bSMikulas Patocka } 1519a2f83e8bSMikulas Patocka 1520a2f83e8bSMikulas Patocka static void account_end_copy(struct dm_snapshot *s) 1521a2f83e8bSMikulas Patocka { 1522a2f83e8bSMikulas Patocka up(&s->cow_count); 1523a2f83e8bSMikulas Patocka } 1524a2f83e8bSMikulas Patocka 15251da177e4SLinus Torvalds /* 15261da177e4SLinus Torvalds * Flush a list of buffers. 15271da177e4SLinus Torvalds */ 15281da177e4SLinus Torvalds static void flush_bios(struct bio *bio) 15291da177e4SLinus Torvalds { 15301da177e4SLinus Torvalds struct bio *n; 15311da177e4SLinus Torvalds 15321da177e4SLinus Torvalds while (bio) { 15331da177e4SLinus Torvalds n = bio->bi_next; 15341da177e4SLinus Torvalds bio->bi_next = NULL; 15351da177e4SLinus Torvalds generic_make_request(bio); 15361da177e4SLinus Torvalds bio = n; 15371da177e4SLinus Torvalds } 15381da177e4SLinus Torvalds } 15391da177e4SLinus Torvalds 1540515ad66cSMikulas Patocka static int do_origin(struct dm_dev *origin, struct bio *bio); 1541515ad66cSMikulas Patocka 1542515ad66cSMikulas Patocka /* 1543515ad66cSMikulas Patocka * Flush a list of buffers. 1544515ad66cSMikulas Patocka */ 1545515ad66cSMikulas Patocka static void retry_origin_bios(struct dm_snapshot *s, struct bio *bio) 1546515ad66cSMikulas Patocka { 1547515ad66cSMikulas Patocka struct bio *n; 1548515ad66cSMikulas Patocka int r; 1549515ad66cSMikulas Patocka 1550515ad66cSMikulas Patocka while (bio) { 1551515ad66cSMikulas Patocka n = bio->bi_next; 1552515ad66cSMikulas Patocka bio->bi_next = NULL; 1553515ad66cSMikulas Patocka r = do_origin(s->origin, bio); 1554515ad66cSMikulas Patocka if (r == DM_MAPIO_REMAPPED) 1555515ad66cSMikulas Patocka generic_make_request(bio); 1556515ad66cSMikulas Patocka bio = n; 1557515ad66cSMikulas Patocka } 1558515ad66cSMikulas Patocka } 1559515ad66cSMikulas Patocka 15601da177e4SLinus Torvalds /* 15611da177e4SLinus Torvalds * Error a list of buffers. 15621da177e4SLinus Torvalds */ 15631da177e4SLinus Torvalds static void error_bios(struct bio *bio) 15641da177e4SLinus Torvalds { 15651da177e4SLinus Torvalds struct bio *n; 15661da177e4SLinus Torvalds 15671da177e4SLinus Torvalds while (bio) { 15681da177e4SLinus Torvalds n = bio->bi_next; 15691da177e4SLinus Torvalds bio->bi_next = NULL; 15706712ecf8SNeilBrown bio_io_error(bio); 15711da177e4SLinus Torvalds bio = n; 15721da177e4SLinus Torvalds } 15731da177e4SLinus Torvalds } 15741da177e4SLinus Torvalds 1575695368acSAlasdair G Kergon static void __invalidate_snapshot(struct dm_snapshot *s, int err) 157676df1c65SAlasdair G Kergon { 157776df1c65SAlasdair G Kergon if (!s->valid) 157876df1c65SAlasdair G Kergon return; 157976df1c65SAlasdair G Kergon 158076df1c65SAlasdair G Kergon if (err == -EIO) 158176df1c65SAlasdair G Kergon DMERR("Invalidating snapshot: Error reading/writing."); 158276df1c65SAlasdair G Kergon else if (err == -ENOMEM) 158376df1c65SAlasdair G Kergon DMERR("Invalidating snapshot: Unable to allocate exception."); 158476df1c65SAlasdair G Kergon 1585493df71cSJonathan Brassow if (s->store->type->drop_snapshot) 1586493df71cSJonathan Brassow s->store->type->drop_snapshot(s->store); 158776df1c65SAlasdair G Kergon 158876df1c65SAlasdair G Kergon s->valid = 0; 158976df1c65SAlasdair G Kergon 1590fc56f6fbSMike Snitzer dm_table_event(s->ti->table); 159176df1c65SAlasdair G Kergon } 159276df1c65SAlasdair G Kergon 15933f1637f2SNikos Tsironis static void invalidate_snapshot(struct dm_snapshot *s, int err) 15943f1637f2SNikos Tsironis { 15953f1637f2SNikos Tsironis down_write(&s->lock); 15963f1637f2SNikos Tsironis __invalidate_snapshot(s, err); 15973f1637f2SNikos Tsironis up_write(&s->lock); 15983f1637f2SNikos Tsironis } 15993f1637f2SNikos Tsironis 1600385277bfSMikulas Patocka static void pending_complete(void *context, int success) 16011da177e4SLinus Torvalds { 1602385277bfSMikulas Patocka struct dm_snap_pending_exception *pe = context; 16031d4989c8SJon Brassow struct dm_exception *e; 16041da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 16059d493fa8SAlasdair G Kergon struct bio *origin_bios = NULL; 16069d493fa8SAlasdair G Kergon struct bio *snapshot_bios = NULL; 1607a6e50b40SMikulas Patocka struct bio *full_bio = NULL; 1608f79ae415SNikos Tsironis struct dm_exception_table_lock lock; 16099d493fa8SAlasdair G Kergon int error = 0; 16101da177e4SLinus Torvalds 1611f79ae415SNikos Tsironis dm_exception_table_lock_init(s, pe->e.old_chunk, &lock); 1612f79ae415SNikos Tsironis 161376df1c65SAlasdair G Kergon if (!success) { 161476df1c65SAlasdair G Kergon /* Read/write error - snapshot is unusable */ 16153f1637f2SNikos Tsironis invalidate_snapshot(s, -EIO); 16169d493fa8SAlasdair G Kergon error = 1; 1617f79ae415SNikos Tsironis 1618f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 161976df1c65SAlasdair G Kergon goto out; 162076df1c65SAlasdair G Kergon } 162176df1c65SAlasdair G Kergon 1622119bc547SMikulas Patocka e = alloc_completed_exception(GFP_NOIO); 162376df1c65SAlasdair G Kergon if (!e) { 16243f1637f2SNikos Tsironis invalidate_snapshot(s, -ENOMEM); 16259d493fa8SAlasdair G Kergon error = 1; 1626f79ae415SNikos Tsironis 1627f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 16281da177e4SLinus Torvalds goto out; 16291da177e4SLinus Torvalds } 16301da177e4SLinus Torvalds *e = pe->e; 16311da177e4SLinus Torvalds 16323f1637f2SNikos Tsironis down_read(&s->lock); 1633f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 16349d493fa8SAlasdair G Kergon if (!s->valid) { 16353f1637f2SNikos Tsironis up_read(&s->lock); 16363510cb94SJon Brassow free_completed_exception(e); 16379d493fa8SAlasdair G Kergon error = 1; 16383f1637f2SNikos Tsironis 16399d493fa8SAlasdair G Kergon goto out; 16409d493fa8SAlasdair G Kergon } 16419d493fa8SAlasdair G Kergon 1642a8d41b59SMikulas Patocka /* 164365fc7c37SNikos Tsironis * Add a proper exception. After inserting the completed exception all 164465fc7c37SNikos Tsironis * subsequent snapshot reads to this chunk will be redirected to the 164565fc7c37SNikos Tsironis * COW device. This ensures that we do not starve. Moreover, as long 164665fc7c37SNikos Tsironis * as the pending exception exists, neither origin writes nor snapshot 164765fc7c37SNikos Tsironis * merging can overwrite the chunk in origin. 16481da177e4SLinus Torvalds */ 16493510cb94SJon Brassow dm_insert_exception(&s->complete, e); 16503f1637f2SNikos Tsironis up_read(&s->lock); 16511da177e4SLinus Torvalds 165265fc7c37SNikos Tsironis /* Wait for conflicting reads to drain */ 165365fc7c37SNikos Tsironis if (__chunk_is_tracked(s, pe->e.old_chunk)) { 1654f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 165565fc7c37SNikos Tsironis __check_for_conflicting_io(s, pe->e.old_chunk); 1656f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 165765fc7c37SNikos Tsironis } 165865fc7c37SNikos Tsironis 16591da177e4SLinus Torvalds out: 166065fc7c37SNikos Tsironis /* Remove the in-flight exception from the list */ 16613510cb94SJon Brassow dm_remove_exception(&pe->e); 1662f79ae415SNikos Tsironis 1663f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 1664f79ae415SNikos Tsironis 16659d493fa8SAlasdair G Kergon snapshot_bios = bio_list_get(&pe->snapshot_bios); 1666515ad66cSMikulas Patocka origin_bios = bio_list_get(&pe->origin_bios); 1667a6e50b40SMikulas Patocka full_bio = pe->full_bio; 1668fe3265b1SMikulas Patocka if (full_bio) 1669a6e50b40SMikulas Patocka full_bio->bi_end_io = pe->full_bio_end_io; 167073dfd078SMikulas Patocka increment_pending_exceptions_done_count(); 167173dfd078SMikulas Patocka 16729d493fa8SAlasdair G Kergon /* Submit any pending write bios */ 1673a6e50b40SMikulas Patocka if (error) { 1674a6e50b40SMikulas Patocka if (full_bio) 1675a6e50b40SMikulas Patocka bio_io_error(full_bio); 16769d493fa8SAlasdair G Kergon error_bios(snapshot_bios); 1677a6e50b40SMikulas Patocka } else { 1678a6e50b40SMikulas Patocka if (full_bio) 16794246a0b6SChristoph Hellwig bio_endio(full_bio); 16809d493fa8SAlasdair G Kergon flush_bios(snapshot_bios); 1681a6e50b40SMikulas Patocka } 16829d493fa8SAlasdair G Kergon 1683515ad66cSMikulas Patocka retry_origin_bios(s, origin_bios); 168422aa66a3SMikulas Patocka 168522aa66a3SMikulas Patocka free_pending_exception(pe); 16861da177e4SLinus Torvalds } 16871da177e4SLinus Torvalds 1688230c83afSMikulas Patocka static void complete_exception(struct dm_snap_pending_exception *pe) 1689230c83afSMikulas Patocka { 1690230c83afSMikulas Patocka struct dm_snapshot *s = pe->snap; 1691230c83afSMikulas Patocka 1692230c83afSMikulas Patocka /* Update the metadata if we are persistent */ 1693385277bfSMikulas Patocka s->store->type->commit_exception(s->store, &pe->e, !pe->copy_error, 1694385277bfSMikulas Patocka pending_complete, pe); 1695230c83afSMikulas Patocka } 1696230c83afSMikulas Patocka 16971da177e4SLinus Torvalds /* 16981da177e4SLinus Torvalds * Called when the copy I/O has finished. kcopyd actually runs 16991da177e4SLinus Torvalds * this code so don't block. 17001da177e4SLinus Torvalds */ 17014cdc1d1fSAlasdair G Kergon static void copy_callback(int read_err, unsigned long write_err, void *context) 17021da177e4SLinus Torvalds { 1703028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = context; 17041da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 17051da177e4SLinus Torvalds 1706230c83afSMikulas Patocka pe->copy_error = read_err || write_err; 17071da177e4SLinus Torvalds 1708230c83afSMikulas Patocka if (pe->exception_sequence == s->exception_complete_sequence) { 17093db2776dSDavid Jeffery struct rb_node *next; 17103db2776dSDavid Jeffery 1711230c83afSMikulas Patocka s->exception_complete_sequence++; 1712230c83afSMikulas Patocka complete_exception(pe); 1713230c83afSMikulas Patocka 17143db2776dSDavid Jeffery next = rb_first(&s->out_of_order_tree); 17153db2776dSDavid Jeffery while (next) { 17163db2776dSDavid Jeffery pe = rb_entry(next, struct dm_snap_pending_exception, 17173db2776dSDavid Jeffery out_of_order_node); 1718230c83afSMikulas Patocka if (pe->exception_sequence != s->exception_complete_sequence) 1719230c83afSMikulas Patocka break; 17203db2776dSDavid Jeffery next = rb_next(next); 1721230c83afSMikulas Patocka s->exception_complete_sequence++; 17223db2776dSDavid Jeffery rb_erase(&pe->out_of_order_node, &s->out_of_order_tree); 1723230c83afSMikulas Patocka complete_exception(pe); 17243db2776dSDavid Jeffery cond_resched(); 1725230c83afSMikulas Patocka } 1726230c83afSMikulas Patocka } else { 17273db2776dSDavid Jeffery struct rb_node *parent = NULL; 17283db2776dSDavid Jeffery struct rb_node **p = &s->out_of_order_tree.rb_node; 1729230c83afSMikulas Patocka struct dm_snap_pending_exception *pe2; 1730230c83afSMikulas Patocka 17313db2776dSDavid Jeffery while (*p) { 17323db2776dSDavid Jeffery pe2 = rb_entry(*p, struct dm_snap_pending_exception, out_of_order_node); 17333db2776dSDavid Jeffery parent = *p; 17343db2776dSDavid Jeffery 17353db2776dSDavid Jeffery BUG_ON(pe->exception_sequence == pe2->exception_sequence); 17363db2776dSDavid Jeffery if (pe->exception_sequence < pe2->exception_sequence) 17373db2776dSDavid Jeffery p = &((*p)->rb_left); 17383db2776dSDavid Jeffery else 17393db2776dSDavid Jeffery p = &((*p)->rb_right); 1740230c83afSMikulas Patocka } 17413db2776dSDavid Jeffery 17423db2776dSDavid Jeffery rb_link_node(&pe->out_of_order_node, parent, p); 17433db2776dSDavid Jeffery rb_insert_color(&pe->out_of_order_node, &s->out_of_order_tree); 1744230c83afSMikulas Patocka } 1745a2f83e8bSMikulas Patocka account_end_copy(s); 17461da177e4SLinus Torvalds } 17471da177e4SLinus Torvalds 17481da177e4SLinus Torvalds /* 17491da177e4SLinus Torvalds * Dispatches the copy operation to kcopyd. 17501da177e4SLinus Torvalds */ 1751028867acSAlasdair G Kergon static void start_copy(struct dm_snap_pending_exception *pe) 17521da177e4SLinus Torvalds { 17531da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 175422a1ceb1SHeinz Mauelshagen struct dm_io_region src, dest; 17551da177e4SLinus Torvalds struct block_device *bdev = s->origin->bdev; 17561da177e4SLinus Torvalds sector_t dev_size; 17571da177e4SLinus Torvalds 17581da177e4SLinus Torvalds dev_size = get_dev_size(bdev); 17591da177e4SLinus Torvalds 17601da177e4SLinus Torvalds src.bdev = bdev; 176171fab00aSJonathan Brassow src.sector = chunk_to_sector(s->store, pe->e.old_chunk); 1762df96eee6SMikulas Patocka src.count = min((sector_t)s->store->chunk_size, dev_size - src.sector); 17631da177e4SLinus Torvalds 1764fc56f6fbSMike Snitzer dest.bdev = s->cow->bdev; 176571fab00aSJonathan Brassow dest.sector = chunk_to_sector(s->store, pe->e.new_chunk); 17661da177e4SLinus Torvalds dest.count = src.count; 17671da177e4SLinus Torvalds 17681da177e4SLinus Torvalds /* Hand over to kcopyd */ 1769a2f83e8bSMikulas Patocka account_start_copy(s); 1770a2d2b034SJonathan Brassow dm_kcopyd_copy(s->kcopyd_client, &src, 1, &dest, 0, copy_callback, pe); 17711da177e4SLinus Torvalds } 17721da177e4SLinus Torvalds 17734246a0b6SChristoph Hellwig static void full_bio_end_io(struct bio *bio) 1774a6e50b40SMikulas Patocka { 1775a6e50b40SMikulas Patocka void *callback_data = bio->bi_private; 1776a6e50b40SMikulas Patocka 17774e4cbee9SChristoph Hellwig dm_kcopyd_do_callback(callback_data, 0, bio->bi_status ? 1 : 0); 1778a6e50b40SMikulas Patocka } 1779a6e50b40SMikulas Patocka 1780a6e50b40SMikulas Patocka static void start_full_bio(struct dm_snap_pending_exception *pe, 1781a6e50b40SMikulas Patocka struct bio *bio) 1782a6e50b40SMikulas Patocka { 1783a6e50b40SMikulas Patocka struct dm_snapshot *s = pe->snap; 1784a6e50b40SMikulas Patocka void *callback_data; 1785a6e50b40SMikulas Patocka 1786a6e50b40SMikulas Patocka pe->full_bio = bio; 1787a6e50b40SMikulas Patocka pe->full_bio_end_io = bio->bi_end_io; 1788a6e50b40SMikulas Patocka 1789a2f83e8bSMikulas Patocka account_start_copy(s); 1790a6e50b40SMikulas Patocka callback_data = dm_kcopyd_prepare_callback(s->kcopyd_client, 1791a6e50b40SMikulas Patocka copy_callback, pe); 1792a6e50b40SMikulas Patocka 1793a6e50b40SMikulas Patocka bio->bi_end_io = full_bio_end_io; 1794a6e50b40SMikulas Patocka bio->bi_private = callback_data; 1795a6e50b40SMikulas Patocka 1796a6e50b40SMikulas Patocka generic_make_request(bio); 1797a6e50b40SMikulas Patocka } 1798a6e50b40SMikulas Patocka 17992913808eSMikulas Patocka static struct dm_snap_pending_exception * 18002913808eSMikulas Patocka __lookup_pending_exception(struct dm_snapshot *s, chunk_t chunk) 18012913808eSMikulas Patocka { 18023510cb94SJon Brassow struct dm_exception *e = dm_lookup_exception(&s->pending, chunk); 18032913808eSMikulas Patocka 18042913808eSMikulas Patocka if (!e) 18052913808eSMikulas Patocka return NULL; 18062913808eSMikulas Patocka 18072913808eSMikulas Patocka return container_of(e, struct dm_snap_pending_exception, e); 18082913808eSMikulas Patocka } 18092913808eSMikulas Patocka 18101da177e4SLinus Torvalds /* 181165fc7c37SNikos Tsironis * Inserts a pending exception into the pending table. 181265fc7c37SNikos Tsironis * 18133f1637f2SNikos Tsironis * NOTE: a write lock must be held on the chunk's pending exception table slot 18143f1637f2SNikos Tsironis * before calling this. 181565fc7c37SNikos Tsironis */ 181665fc7c37SNikos Tsironis static struct dm_snap_pending_exception * 181765fc7c37SNikos Tsironis __insert_pending_exception(struct dm_snapshot *s, 181865fc7c37SNikos Tsironis struct dm_snap_pending_exception *pe, chunk_t chunk) 181965fc7c37SNikos Tsironis { 182065fc7c37SNikos Tsironis pe->e.old_chunk = chunk; 182165fc7c37SNikos Tsironis bio_list_init(&pe->origin_bios); 182265fc7c37SNikos Tsironis bio_list_init(&pe->snapshot_bios); 182365fc7c37SNikos Tsironis pe->started = 0; 182465fc7c37SNikos Tsironis pe->full_bio = NULL; 182565fc7c37SNikos Tsironis 18263f1637f2SNikos Tsironis spin_lock(&s->pe_allocation_lock); 182765fc7c37SNikos Tsironis if (s->store->type->prepare_exception(s->store, &pe->e)) { 18283f1637f2SNikos Tsironis spin_unlock(&s->pe_allocation_lock); 182965fc7c37SNikos Tsironis free_pending_exception(pe); 183065fc7c37SNikos Tsironis return NULL; 183165fc7c37SNikos Tsironis } 183265fc7c37SNikos Tsironis 183365fc7c37SNikos Tsironis pe->exception_sequence = s->exception_start_sequence++; 18343f1637f2SNikos Tsironis spin_unlock(&s->pe_allocation_lock); 183565fc7c37SNikos Tsironis 183665fc7c37SNikos Tsironis dm_insert_exception(&s->pending, &pe->e); 183765fc7c37SNikos Tsironis 183865fc7c37SNikos Tsironis return pe; 183965fc7c37SNikos Tsironis } 184065fc7c37SNikos Tsironis 184165fc7c37SNikos Tsironis /* 18421da177e4SLinus Torvalds * Looks to see if this snapshot already has a pending exception 18431da177e4SLinus Torvalds * for this chunk, otherwise it allocates a new one and inserts 18441da177e4SLinus Torvalds * it into the pending table. 18451da177e4SLinus Torvalds * 18463f1637f2SNikos Tsironis * NOTE: a write lock must be held on the chunk's pending exception table slot 18473f1637f2SNikos Tsironis * before calling this. 18481da177e4SLinus Torvalds */ 1849028867acSAlasdair G Kergon static struct dm_snap_pending_exception * 1850c6621392SMikulas Patocka __find_pending_exception(struct dm_snapshot *s, 1851c6621392SMikulas Patocka struct dm_snap_pending_exception *pe, chunk_t chunk) 18521da177e4SLinus Torvalds { 1853c6621392SMikulas Patocka struct dm_snap_pending_exception *pe2; 185476df1c65SAlasdair G Kergon 18552913808eSMikulas Patocka pe2 = __lookup_pending_exception(s, chunk); 18562913808eSMikulas Patocka if (pe2) { 18571da177e4SLinus Torvalds free_pending_exception(pe); 18582913808eSMikulas Patocka return pe2; 185976df1c65SAlasdair G Kergon } 186076df1c65SAlasdair G Kergon 186165fc7c37SNikos Tsironis return __insert_pending_exception(s, pe, chunk); 18621da177e4SLinus Torvalds } 18631da177e4SLinus Torvalds 18641d4989c8SJon Brassow static void remap_exception(struct dm_snapshot *s, struct dm_exception *e, 1865d74f81f8SMilan Broz struct bio *bio, chunk_t chunk) 18661da177e4SLinus Torvalds { 186774d46992SChristoph Hellwig bio_set_dev(bio, s->cow->bdev); 18684f024f37SKent Overstreet bio->bi_iter.bi_sector = 18694f024f37SKent Overstreet chunk_to_sector(s->store, dm_chunk_number(e->new_chunk) + 1870d74f81f8SMilan Broz (chunk - e->old_chunk)) + 18714f024f37SKent Overstreet (bio->bi_iter.bi_sector & s->store->chunk_mask); 18721da177e4SLinus Torvalds } 18731da177e4SLinus Torvalds 18742e602385SMike Snitzer static void zero_callback(int read_err, unsigned long write_err, void *context) 18752e602385SMike Snitzer { 18762e602385SMike Snitzer struct bio *bio = context; 18772e602385SMike Snitzer struct dm_snapshot *s = bio->bi_private; 18782e602385SMike Snitzer 1879a2f83e8bSMikulas Patocka account_end_copy(s); 18802e602385SMike Snitzer bio->bi_status = write_err ? BLK_STS_IOERR : 0; 18812e602385SMike Snitzer bio_endio(bio); 18822e602385SMike Snitzer } 18832e602385SMike Snitzer 18842e602385SMike Snitzer static void zero_exception(struct dm_snapshot *s, struct dm_exception *e, 18852e602385SMike Snitzer struct bio *bio, chunk_t chunk) 18862e602385SMike Snitzer { 18872e602385SMike Snitzer struct dm_io_region dest; 18882e602385SMike Snitzer 18892e602385SMike Snitzer dest.bdev = s->cow->bdev; 18902e602385SMike Snitzer dest.sector = bio->bi_iter.bi_sector; 18912e602385SMike Snitzer dest.count = s->store->chunk_size; 18922e602385SMike Snitzer 1893a2f83e8bSMikulas Patocka account_start_copy(s); 18942e602385SMike Snitzer WARN_ON_ONCE(bio->bi_private); 18952e602385SMike Snitzer bio->bi_private = s; 18962e602385SMike Snitzer dm_kcopyd_zero(s->kcopyd_client, 1, &dest, 0, zero_callback, bio); 18972e602385SMike Snitzer } 18982e602385SMike Snitzer 18992e602385SMike Snitzer static bool io_overlaps_chunk(struct dm_snapshot *s, struct bio *bio) 19002e602385SMike Snitzer { 19012e602385SMike Snitzer return bio->bi_iter.bi_size == 19022e602385SMike Snitzer (s->store->chunk_size << SECTOR_SHIFT); 19032e602385SMike Snitzer } 19042e602385SMike Snitzer 19057de3ee57SMikulas Patocka static int snapshot_map(struct dm_target *ti, struct bio *bio) 19061da177e4SLinus Torvalds { 19071d4989c8SJon Brassow struct dm_exception *e; 1908028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 1909d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED; 19101da177e4SLinus Torvalds chunk_t chunk; 1911028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = NULL; 1912f79ae415SNikos Tsironis struct dm_exception_table_lock lock; 19131da177e4SLinus Torvalds 1914ee18026aSMikulas Patocka init_tracked_chunk(bio); 1915ee18026aSMikulas Patocka 19161eff9d32SJens Axboe if (bio->bi_opf & REQ_PREFLUSH) { 191774d46992SChristoph Hellwig bio_set_dev(bio, s->cow->bdev); 1918494b3ee7SMikulas Patocka return DM_MAPIO_REMAPPED; 1919494b3ee7SMikulas Patocka } 1920494b3ee7SMikulas Patocka 19214f024f37SKent Overstreet chunk = sector_to_chunk(s->store, bio->bi_iter.bi_sector); 1922f79ae415SNikos Tsironis dm_exception_table_lock_init(s, chunk, &lock); 19231da177e4SLinus Torvalds 19241da177e4SLinus Torvalds /* Full snapshots are not usable */ 192576df1c65SAlasdair G Kergon /* To get here the table must be live so s->active is always set. */ 19261da177e4SLinus Torvalds if (!s->valid) 1927846785e6SChristoph Hellwig return DM_MAPIO_KILL; 19281da177e4SLinus Torvalds 19293f1637f2SNikos Tsironis down_read(&s->lock); 1930f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 19311da177e4SLinus Torvalds 193270246286SChristoph Hellwig if (!s->valid || (unlikely(s->snapshot_overflowed) && 193370246286SChristoph Hellwig bio_data_dir(bio) == WRITE)) { 1934846785e6SChristoph Hellwig r = DM_MAPIO_KILL; 193576df1c65SAlasdair G Kergon goto out_unlock; 193676df1c65SAlasdair G Kergon } 193776df1c65SAlasdair G Kergon 19382e602385SMike Snitzer if (unlikely(bio_op(bio) == REQ_OP_DISCARD)) { 19392e602385SMike Snitzer if (s->discard_passdown_origin && dm_bio_get_target_bio_nr(bio)) { 19402e602385SMike Snitzer /* 19412e602385SMike Snitzer * passdown discard to origin (without triggering 19422e602385SMike Snitzer * snapshot exceptions via do_origin; doing so would 19432e602385SMike Snitzer * defeat the goal of freeing space in origin that is 19442e602385SMike Snitzer * implied by the "discard_passdown_origin" feature) 19452e602385SMike Snitzer */ 19462e602385SMike Snitzer bio_set_dev(bio, s->origin->bdev); 19472e602385SMike Snitzer track_chunk(s, bio, chunk); 19482e602385SMike Snitzer goto out_unlock; 19492e602385SMike Snitzer } 19502e602385SMike Snitzer /* discard to snapshot (target_bio_nr == 0) zeroes exceptions */ 19512e602385SMike Snitzer } 19522e602385SMike Snitzer 19531da177e4SLinus Torvalds /* If the block is already remapped - use that, else remap it */ 19543510cb94SJon Brassow e = dm_lookup_exception(&s->complete, chunk); 19551da177e4SLinus Torvalds if (e) { 1956d74f81f8SMilan Broz remap_exception(s, e, bio, chunk); 19572e602385SMike Snitzer if (unlikely(bio_op(bio) == REQ_OP_DISCARD) && 19582e602385SMike Snitzer io_overlaps_chunk(s, bio)) { 19592e602385SMike Snitzer dm_exception_table_unlock(&lock); 19602e602385SMike Snitzer up_read(&s->lock); 19612e602385SMike Snitzer zero_exception(s, e, bio, chunk); 19622e602385SMike Snitzer r = DM_MAPIO_SUBMITTED; /* discard is not issued */ 19632e602385SMike Snitzer goto out; 19642e602385SMike Snitzer } 19652e602385SMike Snitzer goto out_unlock; 19662e602385SMike Snitzer } 19672e602385SMike Snitzer 19682e602385SMike Snitzer if (unlikely(bio_op(bio) == REQ_OP_DISCARD)) { 19692e602385SMike Snitzer /* 19702e602385SMike Snitzer * If no exception exists, complete discard immediately 19712e602385SMike Snitzer * otherwise it'll trigger copy-out. 19722e602385SMike Snitzer */ 19732e602385SMike Snitzer bio_endio(bio); 19742e602385SMike Snitzer r = DM_MAPIO_SUBMITTED; 197576df1c65SAlasdair G Kergon goto out_unlock; 197676df1c65SAlasdair G Kergon } 19771da177e4SLinus Torvalds 1978ba40a2aaSAlasdair G Kergon /* 1979ba40a2aaSAlasdair G Kergon * Write to snapshot - higher level takes care of RW/RO 1980ba40a2aaSAlasdair G Kergon * flags so we should only get this if we are 1981ba40a2aaSAlasdair G Kergon * writeable. 1982ba40a2aaSAlasdair G Kergon */ 198370246286SChristoph Hellwig if (bio_data_dir(bio) == WRITE) { 19842913808eSMikulas Patocka pe = __lookup_pending_exception(s, chunk); 19852913808eSMikulas Patocka if (!pe) { 1986f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 1987c6621392SMikulas Patocka pe = alloc_pending_exception(s); 1988f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 1989c6621392SMikulas Patocka 19903510cb94SJon Brassow e = dm_lookup_exception(&s->complete, chunk); 199135bf659bSMikulas Patocka if (e) { 199235bf659bSMikulas Patocka free_pending_exception(pe); 199335bf659bSMikulas Patocka remap_exception(s, e, bio, chunk); 199435bf659bSMikulas Patocka goto out_unlock; 199535bf659bSMikulas Patocka } 199635bf659bSMikulas Patocka 1997c6621392SMikulas Patocka pe = __find_pending_exception(s, pe, chunk); 19981da177e4SLinus Torvalds if (!pe) { 1999f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 20003f1637f2SNikos Tsironis up_read(&s->lock); 20013f1637f2SNikos Tsironis 20023f1637f2SNikos Tsironis down_write(&s->lock); 2003f79ae415SNikos Tsironis 2004b0d3cc01SMike Snitzer if (s->store->userspace_supports_overflow) { 20053f1637f2SNikos Tsironis if (s->valid && !s->snapshot_overflowed) { 200676c44f6dSMikulas Patocka s->snapshot_overflowed = 1; 200776c44f6dSMikulas Patocka DMERR("Snapshot overflowed: Unable to allocate exception."); 20083f1637f2SNikos Tsironis } 2009b0d3cc01SMike Snitzer } else 2010b0d3cc01SMike Snitzer __invalidate_snapshot(s, -ENOMEM); 2011f79ae415SNikos Tsironis up_write(&s->lock); 2012f79ae415SNikos Tsironis 2013846785e6SChristoph Hellwig r = DM_MAPIO_KILL; 2014f79ae415SNikos Tsironis goto out; 201576df1c65SAlasdair G Kergon } 20162913808eSMikulas Patocka } 201776df1c65SAlasdair G Kergon 2018d74f81f8SMilan Broz remap_exception(s, &pe->e, bio, chunk); 20191da177e4SLinus Torvalds 2020d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 2021ba40a2aaSAlasdair G Kergon 20222e602385SMike Snitzer if (!pe->started && io_overlaps_chunk(s, bio)) { 2023a6e50b40SMikulas Patocka pe->started = 1; 20243f1637f2SNikos Tsironis 2025f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 20263f1637f2SNikos Tsironis up_read(&s->lock); 20273f1637f2SNikos Tsironis 2028a6e50b40SMikulas Patocka start_full_bio(pe, bio); 2029a6e50b40SMikulas Patocka goto out; 2030a6e50b40SMikulas Patocka } 2031a6e50b40SMikulas Patocka 2032a6e50b40SMikulas Patocka bio_list_add(&pe->snapshot_bios, bio); 2033a6e50b40SMikulas Patocka 20341da177e4SLinus Torvalds if (!pe->started) { 20353f1637f2SNikos Tsironis /* this is protected by the exception table lock */ 20361da177e4SLinus Torvalds pe->started = 1; 20373f1637f2SNikos Tsironis 2038f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 20393f1637f2SNikos Tsironis up_read(&s->lock); 20403f1637f2SNikos Tsironis 204176df1c65SAlasdair G Kergon start_copy(pe); 2042ba40a2aaSAlasdair G Kergon goto out; 2043ba40a2aaSAlasdair G Kergon } 2044cd45daffSMikulas Patocka } else { 204574d46992SChristoph Hellwig bio_set_dev(bio, s->origin->bdev); 2046ee18026aSMikulas Patocka track_chunk(s, bio, chunk); 2047cd45daffSMikulas Patocka } 20481da177e4SLinus Torvalds 2049ba40a2aaSAlasdair G Kergon out_unlock: 2050f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 20513f1637f2SNikos Tsironis up_read(&s->lock); 2052ba40a2aaSAlasdair G Kergon out: 20531da177e4SLinus Torvalds return r; 20541da177e4SLinus Torvalds } 20551da177e4SLinus Torvalds 20563452c2a1SMikulas Patocka /* 20573452c2a1SMikulas Patocka * A snapshot-merge target behaves like a combination of a snapshot 20583452c2a1SMikulas Patocka * target and a snapshot-origin target. It only generates new 20593452c2a1SMikulas Patocka * exceptions in other snapshots and not in the one that is being 20603452c2a1SMikulas Patocka * merged. 20613452c2a1SMikulas Patocka * 20623452c2a1SMikulas Patocka * For each chunk, if there is an existing exception, it is used to 20633452c2a1SMikulas Patocka * redirect I/O to the cow device. Otherwise I/O is sent to the origin, 20643452c2a1SMikulas Patocka * which in turn might generate exceptions in other snapshots. 20659fe86254SMikulas Patocka * If merging is currently taking place on the chunk in question, the 20669fe86254SMikulas Patocka * I/O is deferred by adding it to s->bios_queued_during_merge. 20673452c2a1SMikulas Patocka */ 20687de3ee57SMikulas Patocka static int snapshot_merge_map(struct dm_target *ti, struct bio *bio) 20693452c2a1SMikulas Patocka { 20703452c2a1SMikulas Patocka struct dm_exception *e; 20713452c2a1SMikulas Patocka struct dm_snapshot *s = ti->private; 20723452c2a1SMikulas Patocka int r = DM_MAPIO_REMAPPED; 20733452c2a1SMikulas Patocka chunk_t chunk; 20743452c2a1SMikulas Patocka 2075ee18026aSMikulas Patocka init_tracked_chunk(bio); 2076ee18026aSMikulas Patocka 20771eff9d32SJens Axboe if (bio->bi_opf & REQ_PREFLUSH) { 207855a62eefSAlasdair G Kergon if (!dm_bio_get_target_bio_nr(bio)) 207974d46992SChristoph Hellwig bio_set_dev(bio, s->origin->bdev); 208010b8106aSMike Snitzer else 208174d46992SChristoph Hellwig bio_set_dev(bio, s->cow->bdev); 208210b8106aSMike Snitzer return DM_MAPIO_REMAPPED; 208310b8106aSMike Snitzer } 208410b8106aSMike Snitzer 20853ee25485SMike Snitzer if (unlikely(bio_op(bio) == REQ_OP_DISCARD)) { 20863ee25485SMike Snitzer /* Once merging, discards no longer effect change */ 20873ee25485SMike Snitzer bio_endio(bio); 20883ee25485SMike Snitzer return DM_MAPIO_SUBMITTED; 20893ee25485SMike Snitzer } 20903ee25485SMike Snitzer 20914f024f37SKent Overstreet chunk = sector_to_chunk(s->store, bio->bi_iter.bi_sector); 20923452c2a1SMikulas Patocka 20934ad8d880SNikos Tsironis down_write(&s->lock); 20943452c2a1SMikulas Patocka 2095d2fdb776SMikulas Patocka /* Full merging snapshots are redirected to the origin */ 2096d2fdb776SMikulas Patocka if (!s->valid) 2097d2fdb776SMikulas Patocka goto redirect_to_origin; 20983452c2a1SMikulas Patocka 20993452c2a1SMikulas Patocka /* If the block is already remapped - use that */ 21003452c2a1SMikulas Patocka e = dm_lookup_exception(&s->complete, chunk); 21013452c2a1SMikulas Patocka if (e) { 21029fe86254SMikulas Patocka /* Queue writes overlapping with chunks being merged */ 210370246286SChristoph Hellwig if (bio_data_dir(bio) == WRITE && 21049fe86254SMikulas Patocka chunk >= s->first_merging_chunk && 21059fe86254SMikulas Patocka chunk < (s->first_merging_chunk + 21069fe86254SMikulas Patocka s->num_merging_chunks)) { 210774d46992SChristoph Hellwig bio_set_dev(bio, s->origin->bdev); 21089fe86254SMikulas Patocka bio_list_add(&s->bios_queued_during_merge, bio); 21099fe86254SMikulas Patocka r = DM_MAPIO_SUBMITTED; 21109fe86254SMikulas Patocka goto out_unlock; 21119fe86254SMikulas Patocka } 211217aa0332SMikulas Patocka 21133452c2a1SMikulas Patocka remap_exception(s, e, bio, chunk); 211417aa0332SMikulas Patocka 211570246286SChristoph Hellwig if (bio_data_dir(bio) == WRITE) 2116ee18026aSMikulas Patocka track_chunk(s, bio, chunk); 21173452c2a1SMikulas Patocka goto out_unlock; 21183452c2a1SMikulas Patocka } 21193452c2a1SMikulas Patocka 2120d2fdb776SMikulas Patocka redirect_to_origin: 212174d46992SChristoph Hellwig bio_set_dev(bio, s->origin->bdev); 21223452c2a1SMikulas Patocka 212370246286SChristoph Hellwig if (bio_data_dir(bio) == WRITE) { 21244ad8d880SNikos Tsironis up_write(&s->lock); 21253452c2a1SMikulas Patocka return do_origin(s->origin, bio); 21263452c2a1SMikulas Patocka } 21273452c2a1SMikulas Patocka 21283452c2a1SMikulas Patocka out_unlock: 21294ad8d880SNikos Tsironis up_write(&s->lock); 21303452c2a1SMikulas Patocka 21313452c2a1SMikulas Patocka return r; 21323452c2a1SMikulas Patocka } 21333452c2a1SMikulas Patocka 21344e4cbee9SChristoph Hellwig static int snapshot_end_io(struct dm_target *ti, struct bio *bio, 21354e4cbee9SChristoph Hellwig blk_status_t *error) 2136cd45daffSMikulas Patocka { 2137cd45daffSMikulas Patocka struct dm_snapshot *s = ti->private; 2138cd45daffSMikulas Patocka 2139ee18026aSMikulas Patocka if (is_bio_tracked(bio)) 2140ee18026aSMikulas Patocka stop_tracking_chunk(s, bio); 2141cd45daffSMikulas Patocka 21421be56909SChristoph Hellwig return DM_ENDIO_DONE; 2143cd45daffSMikulas Patocka } 2144cd45daffSMikulas Patocka 21451e03f97eSMikulas Patocka static void snapshot_merge_presuspend(struct dm_target *ti) 21461e03f97eSMikulas Patocka { 21471e03f97eSMikulas Patocka struct dm_snapshot *s = ti->private; 21481e03f97eSMikulas Patocka 21491e03f97eSMikulas Patocka stop_merge(s); 21501e03f97eSMikulas Patocka } 21511e03f97eSMikulas Patocka 2152c1f0c183SMike Snitzer static int snapshot_preresume(struct dm_target *ti) 2153c1f0c183SMike Snitzer { 2154c1f0c183SMike Snitzer int r = 0; 2155c1f0c183SMike Snitzer struct dm_snapshot *s = ti->private; 2156c1f0c183SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 2157c1f0c183SMike Snitzer 2158c1f0c183SMike Snitzer down_read(&_origins_lock); 21599d3b15c4SMikulas Patocka (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); 2160c1f0c183SMike Snitzer if (snap_src && snap_dest) { 21614ad8d880SNikos Tsironis down_read(&snap_src->lock); 2162c1f0c183SMike Snitzer if (s == snap_src) { 2163c1f0c183SMike Snitzer DMERR("Unable to resume snapshot source until " 2164c1f0c183SMike Snitzer "handover completes."); 2165c1f0c183SMike Snitzer r = -EINVAL; 2166b83b2f29SMike Snitzer } else if (!dm_suspended(snap_src->ti)) { 2167c1f0c183SMike Snitzer DMERR("Unable to perform snapshot handover until " 2168c1f0c183SMike Snitzer "source is suspended."); 2169c1f0c183SMike Snitzer r = -EINVAL; 2170c1f0c183SMike Snitzer } 21714ad8d880SNikos Tsironis up_read(&snap_src->lock); 2172c1f0c183SMike Snitzer } 2173c1f0c183SMike Snitzer up_read(&_origins_lock); 2174c1f0c183SMike Snitzer 2175c1f0c183SMike Snitzer return r; 2176c1f0c183SMike Snitzer } 2177c1f0c183SMike Snitzer 21781da177e4SLinus Torvalds static void snapshot_resume(struct dm_target *ti) 21791da177e4SLinus Torvalds { 2180028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 218109ee96b2SMikulas Patocka struct dm_snapshot *snap_src = NULL, *snap_dest = NULL, *snap_merging = NULL; 2182b735fedeSMikulas Patocka struct dm_origin *o; 2183b735fedeSMikulas Patocka struct mapped_device *origin_md = NULL; 218409ee96b2SMikulas Patocka bool must_restart_merging = false; 2185c1f0c183SMike Snitzer 2186c1f0c183SMike Snitzer down_read(&_origins_lock); 2187b735fedeSMikulas Patocka 2188b735fedeSMikulas Patocka o = __lookup_dm_origin(s->origin->bdev); 2189b735fedeSMikulas Patocka if (o) 2190b735fedeSMikulas Patocka origin_md = dm_table_get_md(o->ti->table); 219109ee96b2SMikulas Patocka if (!origin_md) { 219209ee96b2SMikulas Patocka (void) __find_snapshots_sharing_cow(s, NULL, NULL, &snap_merging); 219309ee96b2SMikulas Patocka if (snap_merging) 219409ee96b2SMikulas Patocka origin_md = dm_table_get_md(snap_merging->ti->table); 219509ee96b2SMikulas Patocka } 2196b735fedeSMikulas Patocka if (origin_md == dm_table_get_md(ti->table)) 2197b735fedeSMikulas Patocka origin_md = NULL; 219809ee96b2SMikulas Patocka if (origin_md) { 219909ee96b2SMikulas Patocka if (dm_hold(origin_md)) 220009ee96b2SMikulas Patocka origin_md = NULL; 220109ee96b2SMikulas Patocka } 2202b735fedeSMikulas Patocka 220309ee96b2SMikulas Patocka up_read(&_origins_lock); 220409ee96b2SMikulas Patocka 220509ee96b2SMikulas Patocka if (origin_md) { 2206b735fedeSMikulas Patocka dm_internal_suspend_fast(origin_md); 220709ee96b2SMikulas Patocka if (snap_merging && test_bit(RUNNING_MERGE, &snap_merging->state_bits)) { 220809ee96b2SMikulas Patocka must_restart_merging = true; 220909ee96b2SMikulas Patocka stop_merge(snap_merging); 221009ee96b2SMikulas Patocka } 221109ee96b2SMikulas Patocka } 221209ee96b2SMikulas Patocka 221309ee96b2SMikulas Patocka down_read(&_origins_lock); 2214b735fedeSMikulas Patocka 22159d3b15c4SMikulas Patocka (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); 2216c1f0c183SMike Snitzer if (snap_src && snap_dest) { 22174ad8d880SNikos Tsironis down_write(&snap_src->lock); 22184ad8d880SNikos Tsironis down_write_nested(&snap_dest->lock, SINGLE_DEPTH_NESTING); 2219c1f0c183SMike Snitzer __handover_exceptions(snap_src, snap_dest); 22204ad8d880SNikos Tsironis up_write(&snap_dest->lock); 22214ad8d880SNikos Tsironis up_write(&snap_src->lock); 2222c1f0c183SMike Snitzer } 2223b735fedeSMikulas Patocka 2224c1f0c183SMike Snitzer up_read(&_origins_lock); 2225c1f0c183SMike Snitzer 222609ee96b2SMikulas Patocka if (origin_md) { 222709ee96b2SMikulas Patocka if (must_restart_merging) 222809ee96b2SMikulas Patocka start_merge(snap_merging); 222909ee96b2SMikulas Patocka dm_internal_resume_fast(origin_md); 223009ee96b2SMikulas Patocka dm_put(origin_md); 223109ee96b2SMikulas Patocka } 223209ee96b2SMikulas Patocka 2233c1f0c183SMike Snitzer /* Now we have correct chunk size, reregister */ 2234c1f0c183SMike Snitzer reregister_snapshot(s); 22351da177e4SLinus Torvalds 22364ad8d880SNikos Tsironis down_write(&s->lock); 2237aa14edebSAlasdair G Kergon s->active = 1; 22384ad8d880SNikos Tsironis up_write(&s->lock); 22391da177e4SLinus Torvalds } 22401da177e4SLinus Torvalds 2241542f9038SMike Snitzer static uint32_t get_origin_minimum_chunksize(struct block_device *bdev) 22421e03f97eSMikulas Patocka { 2243542f9038SMike Snitzer uint32_t min_chunksize; 22441e03f97eSMikulas Patocka 22451e03f97eSMikulas Patocka down_read(&_origins_lock); 22461e03f97eSMikulas Patocka min_chunksize = __minimum_chunk_size(__lookup_origin(bdev)); 22471e03f97eSMikulas Patocka up_read(&_origins_lock); 22481e03f97eSMikulas Patocka 22491e03f97eSMikulas Patocka return min_chunksize; 22501e03f97eSMikulas Patocka } 22511e03f97eSMikulas Patocka 22521e03f97eSMikulas Patocka static void snapshot_merge_resume(struct dm_target *ti) 22531e03f97eSMikulas Patocka { 22541e03f97eSMikulas Patocka struct dm_snapshot *s = ti->private; 22551e03f97eSMikulas Patocka 22561e03f97eSMikulas Patocka /* 22571e03f97eSMikulas Patocka * Handover exceptions from existing snapshot. 22581e03f97eSMikulas Patocka */ 22591e03f97eSMikulas Patocka snapshot_resume(ti); 22601e03f97eSMikulas Patocka 22611e03f97eSMikulas Patocka /* 2262542f9038SMike Snitzer * snapshot-merge acts as an origin, so set ti->max_io_len 22631e03f97eSMikulas Patocka */ 2264542f9038SMike Snitzer ti->max_io_len = get_origin_minimum_chunksize(s->origin->bdev); 22651e03f97eSMikulas Patocka 22661e03f97eSMikulas Patocka start_merge(s); 22671e03f97eSMikulas Patocka } 22681e03f97eSMikulas Patocka 2269fd7c092eSMikulas Patocka static void snapshot_status(struct dm_target *ti, status_type_t type, 22701f4e0ff0SAlasdair G Kergon unsigned status_flags, char *result, unsigned maxlen) 22711da177e4SLinus Torvalds { 22722e4a31dfSJonathan Brassow unsigned sz = 0; 2273028867acSAlasdair G Kergon struct dm_snapshot *snap = ti->private; 22742e602385SMike Snitzer unsigned num_features; 22751da177e4SLinus Torvalds 22761da177e4SLinus Torvalds switch (type) { 22771da177e4SLinus Torvalds case STATUSTYPE_INFO: 227894e76572SMikulas Patocka 22794ad8d880SNikos Tsironis down_write(&snap->lock); 228094e76572SMikulas Patocka 22811da177e4SLinus Torvalds if (!snap->valid) 22822e4a31dfSJonathan Brassow DMEMIT("Invalid"); 2283d8ddb1cfSMike Snitzer else if (snap->merge_failed) 2284d8ddb1cfSMike Snitzer DMEMIT("Merge failed"); 228576c44f6dSMikulas Patocka else if (snap->snapshot_overflowed) 228676c44f6dSMikulas Patocka DMEMIT("Overflow"); 22871da177e4SLinus Torvalds else { 2288985903bbSMike Snitzer if (snap->store->type->usage) { 2289985903bbSMike Snitzer sector_t total_sectors, sectors_allocated, 2290985903bbSMike Snitzer metadata_sectors; 2291985903bbSMike Snitzer snap->store->type->usage(snap->store, 2292985903bbSMike Snitzer &total_sectors, 2293985903bbSMike Snitzer §ors_allocated, 2294985903bbSMike Snitzer &metadata_sectors); 2295985903bbSMike Snitzer DMEMIT("%llu/%llu %llu", 2296985903bbSMike Snitzer (unsigned long long)sectors_allocated, 2297985903bbSMike Snitzer (unsigned long long)total_sectors, 2298985903bbSMike Snitzer (unsigned long long)metadata_sectors); 22991da177e4SLinus Torvalds } 23001da177e4SLinus Torvalds else 23012e4a31dfSJonathan Brassow DMEMIT("Unknown"); 23021da177e4SLinus Torvalds } 230394e76572SMikulas Patocka 23044ad8d880SNikos Tsironis up_write(&snap->lock); 230594e76572SMikulas Patocka 23061da177e4SLinus Torvalds break; 23071da177e4SLinus Torvalds 23081da177e4SLinus Torvalds case STATUSTYPE_TABLE: 23091da177e4SLinus Torvalds /* 23101da177e4SLinus Torvalds * kdevname returns a static pointer so we need 23111da177e4SLinus Torvalds * to make private copies if the output is to 23121da177e4SLinus Torvalds * make sense. 23131da177e4SLinus Torvalds */ 2314fc56f6fbSMike Snitzer DMEMIT("%s %s", snap->origin->name, snap->cow->name); 23152e602385SMike Snitzer sz += snap->store->type->status(snap->store, type, result + sz, 23161e302a92SJonathan Brassow maxlen - sz); 23172e602385SMike Snitzer num_features = snap->discard_zeroes_cow + snap->discard_passdown_origin; 23182e602385SMike Snitzer if (num_features) { 23192e602385SMike Snitzer DMEMIT(" %u", num_features); 23202e602385SMike Snitzer if (snap->discard_zeroes_cow) 23212e602385SMike Snitzer DMEMIT(" discard_zeroes_cow"); 23222e602385SMike Snitzer if (snap->discard_passdown_origin) 23232e602385SMike Snitzer DMEMIT(" discard_passdown_origin"); 23242e602385SMike Snitzer } 23251da177e4SLinus Torvalds break; 23261da177e4SLinus Torvalds } 23271da177e4SLinus Torvalds } 23281da177e4SLinus Torvalds 23298811f46cSMike Snitzer static int snapshot_iterate_devices(struct dm_target *ti, 23308811f46cSMike Snitzer iterate_devices_callout_fn fn, void *data) 23318811f46cSMike Snitzer { 23328811f46cSMike Snitzer struct dm_snapshot *snap = ti->private; 23331e5554c8SMikulas Patocka int r; 23348811f46cSMike Snitzer 23351e5554c8SMikulas Patocka r = fn(ti, snap->origin, 0, ti->len, data); 23361e5554c8SMikulas Patocka 23371e5554c8SMikulas Patocka if (!r) 23381e5554c8SMikulas Patocka r = fn(ti, snap->cow, 0, get_dev_size(snap->cow->bdev), data); 23391e5554c8SMikulas Patocka 23401e5554c8SMikulas Patocka return r; 23418811f46cSMike Snitzer } 23428811f46cSMike Snitzer 23432e602385SMike Snitzer static void snapshot_io_hints(struct dm_target *ti, struct queue_limits *limits) 23442e602385SMike Snitzer { 23452e602385SMike Snitzer struct dm_snapshot *snap = ti->private; 23462e602385SMike Snitzer 23472e602385SMike Snitzer if (snap->discard_zeroes_cow) { 23482e602385SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 23492e602385SMike Snitzer 23503ee25485SMike Snitzer down_read(&_origins_lock); 23513ee25485SMike Snitzer 23522e602385SMike Snitzer (void) __find_snapshots_sharing_cow(snap, &snap_src, &snap_dest, NULL); 23532e602385SMike Snitzer if (snap_src && snap_dest) 23542e602385SMike Snitzer snap = snap_src; 23552e602385SMike Snitzer 23562e602385SMike Snitzer /* All discards are split on chunk_size boundary */ 23572e602385SMike Snitzer limits->discard_granularity = snap->store->chunk_size; 23582e602385SMike Snitzer limits->max_discard_sectors = snap->store->chunk_size; 23593ee25485SMike Snitzer 23603ee25485SMike Snitzer up_read(&_origins_lock); 23612e602385SMike Snitzer } 23622e602385SMike Snitzer } 23638811f46cSMike Snitzer 23641da177e4SLinus Torvalds /*----------------------------------------------------------------- 23651da177e4SLinus Torvalds * Origin methods 23661da177e4SLinus Torvalds *---------------------------------------------------------------*/ 23679eaae8ffSMikulas Patocka 23689eaae8ffSMikulas Patocka /* 23699eaae8ffSMikulas Patocka * If no exceptions need creating, DM_MAPIO_REMAPPED is returned and any 23709eaae8ffSMikulas Patocka * supplied bio was ignored. The caller may submit it immediately. 23719eaae8ffSMikulas Patocka * (No remapping actually occurs as the origin is always a direct linear 23729eaae8ffSMikulas Patocka * map.) 23739eaae8ffSMikulas Patocka * 23749eaae8ffSMikulas Patocka * If further exceptions are required, DM_MAPIO_SUBMITTED is returned 23759eaae8ffSMikulas Patocka * and any supplied bio is added to a list to be submitted once all 23769eaae8ffSMikulas Patocka * the necessary exceptions exist. 23779eaae8ffSMikulas Patocka */ 23789eaae8ffSMikulas Patocka static int __origin_write(struct list_head *snapshots, sector_t sector, 23799eaae8ffSMikulas Patocka struct bio *bio) 23801da177e4SLinus Torvalds { 2381515ad66cSMikulas Patocka int r = DM_MAPIO_REMAPPED; 23821da177e4SLinus Torvalds struct dm_snapshot *snap; 23831d4989c8SJon Brassow struct dm_exception *e; 238465fc7c37SNikos Tsironis struct dm_snap_pending_exception *pe, *pe2; 2385515ad66cSMikulas Patocka struct dm_snap_pending_exception *pe_to_start_now = NULL; 2386515ad66cSMikulas Patocka struct dm_snap_pending_exception *pe_to_start_last = NULL; 2387f79ae415SNikos Tsironis struct dm_exception_table_lock lock; 23881da177e4SLinus Torvalds chunk_t chunk; 23891da177e4SLinus Torvalds 23901da177e4SLinus Torvalds /* Do all the snapshots on this origin */ 23911da177e4SLinus Torvalds list_for_each_entry (snap, snapshots, list) { 23923452c2a1SMikulas Patocka /* 23933452c2a1SMikulas Patocka * Don't make new exceptions in a merging snapshot 23943452c2a1SMikulas Patocka * because it has effectively been deleted 23953452c2a1SMikulas Patocka */ 23963452c2a1SMikulas Patocka if (dm_target_is_snapshot_merge(snap->ti)) 23973452c2a1SMikulas Patocka continue; 23983452c2a1SMikulas Patocka 2399d5e404c1SAlasdair G Kergon /* Nothing to do if writing beyond end of snapshot */ 24009eaae8ffSMikulas Patocka if (sector >= dm_table_get_size(snap->ti->table)) 2401f79ae415SNikos Tsironis continue; 24021da177e4SLinus Torvalds 24031da177e4SLinus Torvalds /* 24041da177e4SLinus Torvalds * Remember, different snapshots can have 24051da177e4SLinus Torvalds * different chunk sizes. 24061da177e4SLinus Torvalds */ 24079eaae8ffSMikulas Patocka chunk = sector_to_chunk(snap->store, sector); 2408f79ae415SNikos Tsironis dm_exception_table_lock_init(snap, chunk, &lock); 2409f79ae415SNikos Tsironis 24103f1637f2SNikos Tsironis down_read(&snap->lock); 2411f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 2412f79ae415SNikos Tsironis 2413f79ae415SNikos Tsironis /* Only deal with valid and active snapshots */ 2414f79ae415SNikos Tsironis if (!snap->valid || !snap->active) 2415f79ae415SNikos Tsironis goto next_snapshot; 24161da177e4SLinus Torvalds 241765fc7c37SNikos Tsironis pe = __lookup_pending_exception(snap, chunk); 241865fc7c37SNikos Tsironis if (!pe) { 24191da177e4SLinus Torvalds /* 242065fc7c37SNikos Tsironis * Check exception table to see if block is already 242165fc7c37SNikos Tsironis * remapped in this snapshot and trigger an exception 242265fc7c37SNikos Tsironis * if not. 24231da177e4SLinus Torvalds */ 24243510cb94SJon Brassow e = dm_lookup_exception(&snap->complete, chunk); 242576df1c65SAlasdair G Kergon if (e) 242676df1c65SAlasdair G Kergon goto next_snapshot; 242776df1c65SAlasdair G Kergon 2428f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 2429c6621392SMikulas Patocka pe = alloc_pending_exception(snap); 2430f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 2431c6621392SMikulas Patocka 243265fc7c37SNikos Tsironis pe2 = __lookup_pending_exception(snap, chunk); 243365fc7c37SNikos Tsironis 243465fc7c37SNikos Tsironis if (!pe2) { 24353510cb94SJon Brassow e = dm_lookup_exception(&snap->complete, chunk); 243635bf659bSMikulas Patocka if (e) { 243735bf659bSMikulas Patocka free_pending_exception(pe); 243835bf659bSMikulas Patocka goto next_snapshot; 243935bf659bSMikulas Patocka } 244035bf659bSMikulas Patocka 244165fc7c37SNikos Tsironis pe = __insert_pending_exception(snap, pe, chunk); 24421da177e4SLinus Torvalds if (!pe) { 2443f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 24443f1637f2SNikos Tsironis up_read(&snap->lock); 2445f79ae415SNikos Tsironis 24463f1637f2SNikos Tsironis invalidate_snapshot(snap, -ENOMEM); 2447f79ae415SNikos Tsironis continue; 244876df1c65SAlasdair G Kergon } 244965fc7c37SNikos Tsironis } else { 245065fc7c37SNikos Tsironis free_pending_exception(pe); 245165fc7c37SNikos Tsironis pe = pe2; 245265fc7c37SNikos Tsironis } 24532913808eSMikulas Patocka } 24541da177e4SLinus Torvalds 2455d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 245676df1c65SAlasdair G Kergon 2457515ad66cSMikulas Patocka /* 2458515ad66cSMikulas Patocka * If an origin bio was supplied, queue it to wait for the 2459515ad66cSMikulas Patocka * completion of this exception, and start this one last, 2460515ad66cSMikulas Patocka * at the end of the function. 2461515ad66cSMikulas Patocka */ 2462515ad66cSMikulas Patocka if (bio) { 2463515ad66cSMikulas Patocka bio_list_add(&pe->origin_bios, bio); 2464515ad66cSMikulas Patocka bio = NULL; 2465515ad66cSMikulas Patocka 2466515ad66cSMikulas Patocka if (!pe->started) { 2467515ad66cSMikulas Patocka pe->started = 1; 2468515ad66cSMikulas Patocka pe_to_start_last = pe; 2469515ad66cSMikulas Patocka } 2470b4b610f6SAlasdair G Kergon } 247176df1c65SAlasdair G Kergon 2472eccf0817SAlasdair G Kergon if (!pe->started) { 2473eccf0817SAlasdair G Kergon pe->started = 1; 2474515ad66cSMikulas Patocka pe_to_start_now = pe; 2475eccf0817SAlasdair G Kergon } 24761da177e4SLinus Torvalds 247776df1c65SAlasdair G Kergon next_snapshot: 2478f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 24793f1637f2SNikos Tsironis up_read(&snap->lock); 2480515ad66cSMikulas Patocka 2481515ad66cSMikulas Patocka if (pe_to_start_now) { 2482515ad66cSMikulas Patocka start_copy(pe_to_start_now); 2483515ad66cSMikulas Patocka pe_to_start_now = NULL; 24841da177e4SLinus Torvalds } 2485b4b610f6SAlasdair G Kergon } 2486b4b610f6SAlasdair G Kergon 24871da177e4SLinus Torvalds /* 2488515ad66cSMikulas Patocka * Submit the exception against which the bio is queued last, 2489515ad66cSMikulas Patocka * to give the other exceptions a head start. 24901da177e4SLinus Torvalds */ 2491515ad66cSMikulas Patocka if (pe_to_start_last) 2492515ad66cSMikulas Patocka start_copy(pe_to_start_last); 24931da177e4SLinus Torvalds 24941da177e4SLinus Torvalds return r; 24951da177e4SLinus Torvalds } 24961da177e4SLinus Torvalds 24971da177e4SLinus Torvalds /* 24981da177e4SLinus Torvalds * Called on a write from the origin driver. 24991da177e4SLinus Torvalds */ 25001da177e4SLinus Torvalds static int do_origin(struct dm_dev *origin, struct bio *bio) 25011da177e4SLinus Torvalds { 25021da177e4SLinus Torvalds struct origin *o; 2503d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED; 25041da177e4SLinus Torvalds 25051da177e4SLinus Torvalds down_read(&_origins_lock); 25061da177e4SLinus Torvalds o = __lookup_origin(origin->bdev); 25071da177e4SLinus Torvalds if (o) 25084f024f37SKent Overstreet r = __origin_write(&o->snapshots, bio->bi_iter.bi_sector, bio); 25091da177e4SLinus Torvalds up_read(&_origins_lock); 25101da177e4SLinus Torvalds 25111da177e4SLinus Torvalds return r; 25121da177e4SLinus Torvalds } 25131da177e4SLinus Torvalds 25141da177e4SLinus Torvalds /* 251573dfd078SMikulas Patocka * Trigger exceptions in all non-merging snapshots. 251673dfd078SMikulas Patocka * 251773dfd078SMikulas Patocka * The chunk size of the merging snapshot may be larger than the chunk 251873dfd078SMikulas Patocka * size of some other snapshot so we may need to reallocate multiple 251973dfd078SMikulas Patocka * chunks in other snapshots. 252073dfd078SMikulas Patocka * 252173dfd078SMikulas Patocka * We scan all the overlapping exceptions in the other snapshots. 252273dfd078SMikulas Patocka * Returns 1 if anything was reallocated and must be waited for, 252373dfd078SMikulas Patocka * otherwise returns 0. 252473dfd078SMikulas Patocka * 252573dfd078SMikulas Patocka * size must be a multiple of merging_snap's chunk_size. 252673dfd078SMikulas Patocka */ 252773dfd078SMikulas Patocka static int origin_write_extent(struct dm_snapshot *merging_snap, 252873dfd078SMikulas Patocka sector_t sector, unsigned size) 252973dfd078SMikulas Patocka { 253073dfd078SMikulas Patocka int must_wait = 0; 253173dfd078SMikulas Patocka sector_t n; 253273dfd078SMikulas Patocka struct origin *o; 253373dfd078SMikulas Patocka 253473dfd078SMikulas Patocka /* 2535542f9038SMike Snitzer * The origin's __minimum_chunk_size() got stored in max_io_len 253673dfd078SMikulas Patocka * by snapshot_merge_resume(). 253773dfd078SMikulas Patocka */ 253873dfd078SMikulas Patocka down_read(&_origins_lock); 253973dfd078SMikulas Patocka o = __lookup_origin(merging_snap->origin->bdev); 2540542f9038SMike Snitzer for (n = 0; n < size; n += merging_snap->ti->max_io_len) 254173dfd078SMikulas Patocka if (__origin_write(&o->snapshots, sector + n, NULL) == 254273dfd078SMikulas Patocka DM_MAPIO_SUBMITTED) 254373dfd078SMikulas Patocka must_wait = 1; 254473dfd078SMikulas Patocka up_read(&_origins_lock); 254573dfd078SMikulas Patocka 254673dfd078SMikulas Patocka return must_wait; 254773dfd078SMikulas Patocka } 254873dfd078SMikulas Patocka 254973dfd078SMikulas Patocka /* 25501da177e4SLinus Torvalds * Origin: maps a linear range of a device, with hooks for snapshotting. 25511da177e4SLinus Torvalds */ 25521da177e4SLinus Torvalds 25531da177e4SLinus Torvalds /* 25541da177e4SLinus Torvalds * Construct an origin mapping: <dev_path> 25551da177e4SLinus Torvalds * The context for an origin is merely a 'struct dm_dev *' 25561da177e4SLinus Torvalds * pointing to the real device. 25571da177e4SLinus Torvalds */ 25581da177e4SLinus Torvalds static int origin_ctr(struct dm_target *ti, unsigned int argc, char **argv) 25591da177e4SLinus Torvalds { 25601da177e4SLinus Torvalds int r; 2561599cdf3bSMikulas Patocka struct dm_origin *o; 25621da177e4SLinus Torvalds 25631da177e4SLinus Torvalds if (argc != 1) { 256472d94861SAlasdair G Kergon ti->error = "origin: incorrect number of arguments"; 25651da177e4SLinus Torvalds return -EINVAL; 25661da177e4SLinus Torvalds } 25671da177e4SLinus Torvalds 2568599cdf3bSMikulas Patocka o = kmalloc(sizeof(struct dm_origin), GFP_KERNEL); 2569599cdf3bSMikulas Patocka if (!o) { 2570599cdf3bSMikulas Patocka ti->error = "Cannot allocate private origin structure"; 2571599cdf3bSMikulas Patocka r = -ENOMEM; 2572599cdf3bSMikulas Patocka goto bad_alloc; 25731da177e4SLinus Torvalds } 25741da177e4SLinus Torvalds 2575599cdf3bSMikulas Patocka r = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &o->dev); 2576599cdf3bSMikulas Patocka if (r) { 2577599cdf3bSMikulas Patocka ti->error = "Cannot get target device"; 2578599cdf3bSMikulas Patocka goto bad_open; 2579599cdf3bSMikulas Patocka } 2580599cdf3bSMikulas Patocka 2581b735fedeSMikulas Patocka o->ti = ti; 2582599cdf3bSMikulas Patocka ti->private = o; 258355a62eefSAlasdair G Kergon ti->num_flush_bios = 1; 2584494b3ee7SMikulas Patocka 25851da177e4SLinus Torvalds return 0; 2586599cdf3bSMikulas Patocka 2587599cdf3bSMikulas Patocka bad_open: 2588599cdf3bSMikulas Patocka kfree(o); 2589599cdf3bSMikulas Patocka bad_alloc: 2590599cdf3bSMikulas Patocka return r; 25911da177e4SLinus Torvalds } 25921da177e4SLinus Torvalds 25931da177e4SLinus Torvalds static void origin_dtr(struct dm_target *ti) 25941da177e4SLinus Torvalds { 2595599cdf3bSMikulas Patocka struct dm_origin *o = ti->private; 2596b735fedeSMikulas Patocka 2597599cdf3bSMikulas Patocka dm_put_device(ti, o->dev); 2598599cdf3bSMikulas Patocka kfree(o); 25991da177e4SLinus Torvalds } 26001da177e4SLinus Torvalds 26017de3ee57SMikulas Patocka static int origin_map(struct dm_target *ti, struct bio *bio) 26021da177e4SLinus Torvalds { 2603599cdf3bSMikulas Patocka struct dm_origin *o = ti->private; 2604298eaa89SMikulas Patocka unsigned available_sectors; 26051da177e4SLinus Torvalds 260674d46992SChristoph Hellwig bio_set_dev(bio, o->dev->bdev); 26071da177e4SLinus Torvalds 26081eff9d32SJens Axboe if (unlikely(bio->bi_opf & REQ_PREFLUSH)) 2609494b3ee7SMikulas Patocka return DM_MAPIO_REMAPPED; 2610494b3ee7SMikulas Patocka 261170246286SChristoph Hellwig if (bio_data_dir(bio) != WRITE) 2612298eaa89SMikulas Patocka return DM_MAPIO_REMAPPED; 2613298eaa89SMikulas Patocka 2614298eaa89SMikulas Patocka available_sectors = o->split_boundary - 2615298eaa89SMikulas Patocka ((unsigned)bio->bi_iter.bi_sector & (o->split_boundary - 1)); 2616298eaa89SMikulas Patocka 2617298eaa89SMikulas Patocka if (bio_sectors(bio) > available_sectors) 2618298eaa89SMikulas Patocka dm_accept_partial_bio(bio, available_sectors); 2619298eaa89SMikulas Patocka 26201da177e4SLinus Torvalds /* Only tell snapshots if this is a write */ 2621298eaa89SMikulas Patocka return do_origin(o->dev, bio); 26221da177e4SLinus Torvalds } 26231da177e4SLinus Torvalds 26241da177e4SLinus Torvalds /* 2625542f9038SMike Snitzer * Set the target "max_io_len" field to the minimum of all the snapshots' 26261da177e4SLinus Torvalds * chunk sizes. 26271da177e4SLinus Torvalds */ 26281da177e4SLinus Torvalds static void origin_resume(struct dm_target *ti) 26291da177e4SLinus Torvalds { 2630599cdf3bSMikulas Patocka struct dm_origin *o = ti->private; 26311da177e4SLinus Torvalds 2632298eaa89SMikulas Patocka o->split_boundary = get_origin_minimum_chunksize(o->dev->bdev); 2633b735fedeSMikulas Patocka 2634b735fedeSMikulas Patocka down_write(&_origins_lock); 2635b735fedeSMikulas Patocka __insert_dm_origin(o); 2636b735fedeSMikulas Patocka up_write(&_origins_lock); 2637b735fedeSMikulas Patocka } 2638b735fedeSMikulas Patocka 2639b735fedeSMikulas Patocka static void origin_postsuspend(struct dm_target *ti) 2640b735fedeSMikulas Patocka { 2641b735fedeSMikulas Patocka struct dm_origin *o = ti->private; 2642b735fedeSMikulas Patocka 2643b735fedeSMikulas Patocka down_write(&_origins_lock); 2644b735fedeSMikulas Patocka __remove_dm_origin(o); 2645b735fedeSMikulas Patocka up_write(&_origins_lock); 26461da177e4SLinus Torvalds } 26471da177e4SLinus Torvalds 2648fd7c092eSMikulas Patocka static void origin_status(struct dm_target *ti, status_type_t type, 26491f4e0ff0SAlasdair G Kergon unsigned status_flags, char *result, unsigned maxlen) 26501da177e4SLinus Torvalds { 2651599cdf3bSMikulas Patocka struct dm_origin *o = ti->private; 26521da177e4SLinus Torvalds 26531da177e4SLinus Torvalds switch (type) { 26541da177e4SLinus Torvalds case STATUSTYPE_INFO: 26551da177e4SLinus Torvalds result[0] = '\0'; 26561da177e4SLinus Torvalds break; 26571da177e4SLinus Torvalds 26581da177e4SLinus Torvalds case STATUSTYPE_TABLE: 2659599cdf3bSMikulas Patocka snprintf(result, maxlen, "%s", o->dev->name); 26601da177e4SLinus Torvalds break; 26611da177e4SLinus Torvalds } 26621da177e4SLinus Torvalds } 26631da177e4SLinus Torvalds 26648811f46cSMike Snitzer static int origin_iterate_devices(struct dm_target *ti, 26658811f46cSMike Snitzer iterate_devices_callout_fn fn, void *data) 26668811f46cSMike Snitzer { 2667599cdf3bSMikulas Patocka struct dm_origin *o = ti->private; 26688811f46cSMike Snitzer 2669599cdf3bSMikulas Patocka return fn(ti, o->dev, 0, ti->len, data); 26708811f46cSMike Snitzer } 26718811f46cSMike Snitzer 26721da177e4SLinus Torvalds static struct target_type origin_target = { 26731da177e4SLinus Torvalds .name = "snapshot-origin", 2674b735fedeSMikulas Patocka .version = {1, 9, 0}, 26751da177e4SLinus Torvalds .module = THIS_MODULE, 26761da177e4SLinus Torvalds .ctr = origin_ctr, 26771da177e4SLinus Torvalds .dtr = origin_dtr, 26781da177e4SLinus Torvalds .map = origin_map, 26791da177e4SLinus Torvalds .resume = origin_resume, 2680b735fedeSMikulas Patocka .postsuspend = origin_postsuspend, 26811da177e4SLinus Torvalds .status = origin_status, 26828811f46cSMike Snitzer .iterate_devices = origin_iterate_devices, 26831da177e4SLinus Torvalds }; 26841da177e4SLinus Torvalds 26851da177e4SLinus Torvalds static struct target_type snapshot_target = { 26861da177e4SLinus Torvalds .name = "snapshot", 26872e602385SMike Snitzer .version = {1, 16, 0}, 26881da177e4SLinus Torvalds .module = THIS_MODULE, 26891da177e4SLinus Torvalds .ctr = snapshot_ctr, 26901da177e4SLinus Torvalds .dtr = snapshot_dtr, 26911da177e4SLinus Torvalds .map = snapshot_map, 2692cd45daffSMikulas Patocka .end_io = snapshot_end_io, 2693c1f0c183SMike Snitzer .preresume = snapshot_preresume, 26941da177e4SLinus Torvalds .resume = snapshot_resume, 26951da177e4SLinus Torvalds .status = snapshot_status, 26968811f46cSMike Snitzer .iterate_devices = snapshot_iterate_devices, 26972e602385SMike Snitzer .io_hints = snapshot_io_hints, 26981da177e4SLinus Torvalds }; 26991da177e4SLinus Torvalds 2700d698aa45SMikulas Patocka static struct target_type merge_target = { 2701d698aa45SMikulas Patocka .name = dm_snapshot_merge_target_name, 27022e602385SMike Snitzer .version = {1, 5, 0}, 2703d698aa45SMikulas Patocka .module = THIS_MODULE, 2704d698aa45SMikulas Patocka .ctr = snapshot_ctr, 2705d698aa45SMikulas Patocka .dtr = snapshot_dtr, 27063452c2a1SMikulas Patocka .map = snapshot_merge_map, 2707d698aa45SMikulas Patocka .end_io = snapshot_end_io, 27081e03f97eSMikulas Patocka .presuspend = snapshot_merge_presuspend, 2709d698aa45SMikulas Patocka .preresume = snapshot_preresume, 27101e03f97eSMikulas Patocka .resume = snapshot_merge_resume, 2711d698aa45SMikulas Patocka .status = snapshot_status, 2712d698aa45SMikulas Patocka .iterate_devices = snapshot_iterate_devices, 27132e602385SMike Snitzer .io_hints = snapshot_io_hints, 2714d698aa45SMikulas Patocka }; 2715d698aa45SMikulas Patocka 27161da177e4SLinus Torvalds static int __init dm_snapshot_init(void) 27171da177e4SLinus Torvalds { 27181da177e4SLinus Torvalds int r; 27191da177e4SLinus Torvalds 27204db6bfe0SAlasdair G Kergon r = dm_exception_store_init(); 27214db6bfe0SAlasdair G Kergon if (r) { 27224db6bfe0SAlasdair G Kergon DMERR("Failed to initialize exception stores"); 27234db6bfe0SAlasdair G Kergon return r; 27244db6bfe0SAlasdair G Kergon } 27254db6bfe0SAlasdair G Kergon 27261da177e4SLinus Torvalds r = init_origin_hash(); 27271da177e4SLinus Torvalds if (r) { 27281da177e4SLinus Torvalds DMERR("init_origin_hash failed."); 2729d698aa45SMikulas Patocka goto bad_origin_hash; 27301da177e4SLinus Torvalds } 27311da177e4SLinus Torvalds 27321d4989c8SJon Brassow exception_cache = KMEM_CACHE(dm_exception, 0); 27331da177e4SLinus Torvalds if (!exception_cache) { 27341da177e4SLinus Torvalds DMERR("Couldn't create exception cache."); 27351da177e4SLinus Torvalds r = -ENOMEM; 2736d698aa45SMikulas Patocka goto bad_exception_cache; 27371da177e4SLinus Torvalds } 27381da177e4SLinus Torvalds 2739028867acSAlasdair G Kergon pending_cache = KMEM_CACHE(dm_snap_pending_exception, 0); 27401da177e4SLinus Torvalds if (!pending_cache) { 27411da177e4SLinus Torvalds DMERR("Couldn't create pending cache."); 27421da177e4SLinus Torvalds r = -ENOMEM; 2743d698aa45SMikulas Patocka goto bad_pending_cache; 27441da177e4SLinus Torvalds } 27451da177e4SLinus Torvalds 27467e6358d2Smonty_pavel@sina.com r = dm_register_target(&snapshot_target); 27477e6358d2Smonty_pavel@sina.com if (r < 0) { 27487e6358d2Smonty_pavel@sina.com DMERR("snapshot target register failed %d", r); 27497e6358d2Smonty_pavel@sina.com goto bad_register_snapshot_target; 27507e6358d2Smonty_pavel@sina.com } 27517e6358d2Smonty_pavel@sina.com 27527e6358d2Smonty_pavel@sina.com r = dm_register_target(&origin_target); 27537e6358d2Smonty_pavel@sina.com if (r < 0) { 27547e6358d2Smonty_pavel@sina.com DMERR("Origin target register failed %d", r); 27557e6358d2Smonty_pavel@sina.com goto bad_register_origin_target; 27567e6358d2Smonty_pavel@sina.com } 27577e6358d2Smonty_pavel@sina.com 27587e6358d2Smonty_pavel@sina.com r = dm_register_target(&merge_target); 27597e6358d2Smonty_pavel@sina.com if (r < 0) { 27607e6358d2Smonty_pavel@sina.com DMERR("Merge target register failed %d", r); 27617e6358d2Smonty_pavel@sina.com goto bad_register_merge_target; 27627e6358d2Smonty_pavel@sina.com } 27637e6358d2Smonty_pavel@sina.com 27641da177e4SLinus Torvalds return 0; 27651da177e4SLinus Torvalds 2766d698aa45SMikulas Patocka bad_register_merge_target: 27671da177e4SLinus Torvalds dm_unregister_target(&origin_target); 2768d698aa45SMikulas Patocka bad_register_origin_target: 27691da177e4SLinus Torvalds dm_unregister_target(&snapshot_target); 2770034a186dSJonathan Brassow bad_register_snapshot_target: 27717e6358d2Smonty_pavel@sina.com kmem_cache_destroy(pending_cache); 27727e6358d2Smonty_pavel@sina.com bad_pending_cache: 27737e6358d2Smonty_pavel@sina.com kmem_cache_destroy(exception_cache); 27747e6358d2Smonty_pavel@sina.com bad_exception_cache: 27757e6358d2Smonty_pavel@sina.com exit_origin_hash(); 27767e6358d2Smonty_pavel@sina.com bad_origin_hash: 2777034a186dSJonathan Brassow dm_exception_store_exit(); 2778d698aa45SMikulas Patocka 27791da177e4SLinus Torvalds return r; 27801da177e4SLinus Torvalds } 27811da177e4SLinus Torvalds 27821da177e4SLinus Torvalds static void __exit dm_snapshot_exit(void) 27831da177e4SLinus Torvalds { 278410d3bd09SMikulas Patocka dm_unregister_target(&snapshot_target); 278510d3bd09SMikulas Patocka dm_unregister_target(&origin_target); 2786d698aa45SMikulas Patocka dm_unregister_target(&merge_target); 27871da177e4SLinus Torvalds 27881da177e4SLinus Torvalds exit_origin_hash(); 27891da177e4SLinus Torvalds kmem_cache_destroy(pending_cache); 27901da177e4SLinus Torvalds kmem_cache_destroy(exception_cache); 27914db6bfe0SAlasdair G Kergon 27924db6bfe0SAlasdair G Kergon dm_exception_store_exit(); 27931da177e4SLinus Torvalds } 27941da177e4SLinus Torvalds 27951da177e4SLinus Torvalds /* Module hooks */ 27961da177e4SLinus Torvalds module_init(dm_snapshot_init); 27971da177e4SLinus Torvalds module_exit(dm_snapshot_exit); 27981da177e4SLinus Torvalds 27991da177e4SLinus Torvalds MODULE_DESCRIPTION(DM_NAME " snapshot target"); 28001da177e4SLinus Torvalds MODULE_AUTHOR("Joe Thornber"); 28011da177e4SLinus Torvalds MODULE_LICENSE("GPL"); 280223cb2109SMikulas Patocka MODULE_ALIAS("dm-snapshot-origin"); 280323cb2109SMikulas Patocka MODULE_ALIAS("dm-snapshot-merge"); 2804