13bd94003SHeinz Mauelshagen // SPDX-License-Identifier: GPL-2.0-only 21da177e4SLinus Torvalds /* 31da177e4SLinus Torvalds * Copyright (C) 2001-2002 Sistina Software (UK) Limited. 41da177e4SLinus Torvalds * 51da177e4SLinus Torvalds * This file is released under the GPL. 61da177e4SLinus Torvalds */ 71da177e4SLinus Torvalds 81da177e4SLinus Torvalds #include <linux/blkdev.h> 91da177e4SLinus Torvalds #include <linux/device-mapper.h> 1090fa1527SMikulas Patocka #include <linux/delay.h> 111da177e4SLinus Torvalds #include <linux/fs.h> 121da177e4SLinus Torvalds #include <linux/init.h> 131da177e4SLinus Torvalds #include <linux/kdev_t.h> 141da177e4SLinus Torvalds #include <linux/list.h> 15f79ae415SNikos Tsironis #include <linux/list_bl.h> 161da177e4SLinus Torvalds #include <linux/mempool.h> 171da177e4SLinus Torvalds #include <linux/module.h> 181da177e4SLinus Torvalds #include <linux/slab.h> 191da177e4SLinus Torvalds #include <linux/vmalloc.h> 206f3c3f0aSvignesh babu #include <linux/log2.h> 21a765e20eSAlasdair G Kergon #include <linux/dm-kcopyd.h> 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; 4586a3238cSHeinz Mauelshagen unsigned int 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 11086a3238cSHeinz Mauelshagen unsigned int in_progress; 111b2155578SMikulas Patocka struct wait_queue_head in_progress_wait; 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 16586a3238cSHeinz Mauelshagen static unsigned int cow_threshold = DEFAULT_COW_THRESHOLD; 166b2155578SMikulas Patocka module_param_named(snapshot_cow_threshold, cow_threshold, uint, 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, 301238d991fSHeinz Mauelshagen * so fsleep(1000) 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)) 306238d991fSHeinz Mauelshagen fsleep(1000); 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; 32886a3238cSHeinz Mauelshagen unsigned int 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 38186a3238cSHeinz Mauelshagen static unsigned int 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, 65686a3238cSHeinz Mauelshagen uint32_t size, unsigned int 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; 6627a35693aSMatthew Wilcox (Oracle) et->table = kvmalloc_array(size, sizeof(struct hlist_bl_head), 6637a35693aSMatthew Wilcox (Oracle) GFP_KERNEL); 6641da177e4SLinus Torvalds if (!et->table) 6651da177e4SLinus Torvalds return -ENOMEM; 6661da177e4SLinus Torvalds 6671da177e4SLinus Torvalds for (i = 0; i < size; i++) 668f79ae415SNikos Tsironis INIT_HLIST_BL_HEAD(et->table + i); 6691da177e4SLinus Torvalds 6701da177e4SLinus Torvalds return 0; 6711da177e4SLinus Torvalds } 6721da177e4SLinus Torvalds 6733510cb94SJon Brassow static void dm_exception_table_exit(struct dm_exception_table *et, 674191437a5SJon Brassow struct kmem_cache *mem) 6751da177e4SLinus Torvalds { 676f79ae415SNikos Tsironis struct hlist_bl_head *slot; 677f79ae415SNikos Tsironis struct dm_exception *ex; 678f79ae415SNikos Tsironis struct hlist_bl_node *pos, *n; 6791da177e4SLinus Torvalds int i, size; 6801da177e4SLinus Torvalds 6811da177e4SLinus Torvalds size = et->hash_mask + 1; 6821da177e4SLinus Torvalds for (i = 0; i < size; i++) { 6831da177e4SLinus Torvalds slot = et->table + i; 6841da177e4SLinus Torvalds 685f79ae415SNikos Tsironis hlist_bl_for_each_entry_safe(ex, pos, n, slot, hash_list) 6861da177e4SLinus Torvalds kmem_cache_free(mem, ex); 6871da177e4SLinus Torvalds } 6881da177e4SLinus Torvalds 6897a35693aSMatthew Wilcox (Oracle) kvfree(et->table); 6901da177e4SLinus Torvalds } 6911da177e4SLinus Torvalds 692191437a5SJon Brassow static uint32_t exception_hash(struct dm_exception_table *et, chunk_t chunk) 6931da177e4SLinus Torvalds { 694d74f81f8SMilan Broz return (chunk >> et->hash_shift) & et->hash_mask; 6951da177e4SLinus Torvalds } 6961da177e4SLinus Torvalds 6973510cb94SJon Brassow static void dm_remove_exception(struct dm_exception *e) 6981da177e4SLinus Torvalds { 699f79ae415SNikos Tsironis hlist_bl_del(&e->hash_list); 7001da177e4SLinus Torvalds } 7011da177e4SLinus Torvalds 7021da177e4SLinus Torvalds /* 7031da177e4SLinus Torvalds * Return the exception data for a sector, or NULL if not 7041da177e4SLinus Torvalds * remapped. 7051da177e4SLinus Torvalds */ 7063510cb94SJon Brassow static struct dm_exception *dm_lookup_exception(struct dm_exception_table *et, 7071da177e4SLinus Torvalds chunk_t chunk) 7081da177e4SLinus Torvalds { 709f79ae415SNikos Tsironis struct hlist_bl_head *slot; 710f79ae415SNikos Tsironis struct hlist_bl_node *pos; 7111d4989c8SJon Brassow struct dm_exception *e; 7121da177e4SLinus Torvalds 7131da177e4SLinus Torvalds slot = &et->table[exception_hash(et, chunk)]; 714f79ae415SNikos Tsironis hlist_bl_for_each_entry(e, pos, slot, hash_list) 715d74f81f8SMilan Broz if (chunk >= e->old_chunk && 716d74f81f8SMilan Broz chunk <= e->old_chunk + dm_consecutive_chunk_count(e)) 7171da177e4SLinus Torvalds return e; 7181da177e4SLinus Torvalds 7191da177e4SLinus Torvalds return NULL; 7201da177e4SLinus Torvalds } 7211da177e4SLinus Torvalds 722119bc547SMikulas Patocka static struct dm_exception *alloc_completed_exception(gfp_t gfp) 7231da177e4SLinus Torvalds { 7241d4989c8SJon Brassow struct dm_exception *e; 7251da177e4SLinus Torvalds 726119bc547SMikulas Patocka e = kmem_cache_alloc(exception_cache, gfp); 727119bc547SMikulas Patocka if (!e && gfp == GFP_NOIO) 7281da177e4SLinus Torvalds e = kmem_cache_alloc(exception_cache, GFP_ATOMIC); 7291da177e4SLinus Torvalds 7301da177e4SLinus Torvalds return e; 7311da177e4SLinus Torvalds } 7321da177e4SLinus Torvalds 7333510cb94SJon Brassow static void free_completed_exception(struct dm_exception *e) 7341da177e4SLinus Torvalds { 7351da177e4SLinus Torvalds kmem_cache_free(exception_cache, e); 7361da177e4SLinus Torvalds } 7371da177e4SLinus Torvalds 73892e86812SMikulas Patocka static struct dm_snap_pending_exception *alloc_pending_exception(struct dm_snapshot *s) 7391da177e4SLinus Torvalds { 7406f1c819cSKent Overstreet struct dm_snap_pending_exception *pe = mempool_alloc(&s->pending_pool, 74192e86812SMikulas Patocka GFP_NOIO); 74292e86812SMikulas Patocka 743879129d2SMikulas Patocka atomic_inc(&s->pending_exceptions_count); 74492e86812SMikulas Patocka pe->snap = s; 74592e86812SMikulas Patocka 74692e86812SMikulas Patocka return pe; 7471da177e4SLinus Torvalds } 7481da177e4SLinus Torvalds 749028867acSAlasdair G Kergon static void free_pending_exception(struct dm_snap_pending_exception *pe) 7501da177e4SLinus Torvalds { 751879129d2SMikulas Patocka struct dm_snapshot *s = pe->snap; 752879129d2SMikulas Patocka 7536f1c819cSKent Overstreet mempool_free(pe, &s->pending_pool); 7544e857c58SPeter Zijlstra smp_mb__before_atomic(); 755879129d2SMikulas Patocka atomic_dec(&s->pending_exceptions_count); 7561da177e4SLinus Torvalds } 7571da177e4SLinus Torvalds 7583510cb94SJon Brassow static void dm_insert_exception(struct dm_exception_table *eh, 7591d4989c8SJon Brassow struct dm_exception *new_e) 760d74f81f8SMilan Broz { 761f79ae415SNikos Tsironis struct hlist_bl_head *l; 762f79ae415SNikos Tsironis struct hlist_bl_node *pos; 7631d4989c8SJon Brassow struct dm_exception *e = NULL; 764d74f81f8SMilan Broz 765d74f81f8SMilan Broz l = &eh->table[exception_hash(eh, new_e->old_chunk)]; 766d74f81f8SMilan Broz 767d74f81f8SMilan Broz /* Add immediately if this table doesn't support consecutive chunks */ 768d74f81f8SMilan Broz if (!eh->hash_shift) 769d74f81f8SMilan Broz goto out; 770d74f81f8SMilan Broz 771d74f81f8SMilan Broz /* List is ordered by old_chunk */ 772f79ae415SNikos Tsironis hlist_bl_for_each_entry(e, pos, l, hash_list) { 773d74f81f8SMilan Broz /* Insert after an existing chunk? */ 774d74f81f8SMilan Broz if (new_e->old_chunk == (e->old_chunk + 775d74f81f8SMilan Broz dm_consecutive_chunk_count(e) + 1) && 776d74f81f8SMilan Broz new_e->new_chunk == (dm_chunk_number(e->new_chunk) + 777d74f81f8SMilan Broz dm_consecutive_chunk_count(e) + 1)) { 778d74f81f8SMilan Broz dm_consecutive_chunk_count_inc(e); 7793510cb94SJon Brassow free_completed_exception(new_e); 780d74f81f8SMilan Broz return; 781d74f81f8SMilan Broz } 782d74f81f8SMilan Broz 783d74f81f8SMilan Broz /* Insert before an existing chunk? */ 784d74f81f8SMilan Broz if (new_e->old_chunk == (e->old_chunk - 1) && 785d74f81f8SMilan Broz new_e->new_chunk == (dm_chunk_number(e->new_chunk) - 1)) { 786d74f81f8SMilan Broz dm_consecutive_chunk_count_inc(e); 787d74f81f8SMilan Broz e->old_chunk--; 788d74f81f8SMilan Broz e->new_chunk--; 7893510cb94SJon Brassow free_completed_exception(new_e); 790d74f81f8SMilan Broz return; 791d74f81f8SMilan Broz } 792d74f81f8SMilan Broz 793f79ae415SNikos Tsironis if (new_e->old_chunk < e->old_chunk) 794d74f81f8SMilan Broz break; 795d74f81f8SMilan Broz } 796d74f81f8SMilan Broz 797d74f81f8SMilan Broz out: 798f79ae415SNikos Tsironis if (!e) { 799f79ae415SNikos Tsironis /* 800f79ae415SNikos Tsironis * Either the table doesn't support consecutive chunks or slot 801f79ae415SNikos Tsironis * l is empty. 802f79ae415SNikos Tsironis */ 803f79ae415SNikos Tsironis hlist_bl_add_head(&new_e->hash_list, l); 804f79ae415SNikos Tsironis } else if (new_e->old_chunk < e->old_chunk) { 805f79ae415SNikos Tsironis /* Add before an existing exception */ 806f79ae415SNikos Tsironis hlist_bl_add_before(&new_e->hash_list, &e->hash_list); 807f79ae415SNikos Tsironis } else { 808f79ae415SNikos Tsironis /* Add to l's tail: e is the last exception in this slot */ 809f79ae415SNikos Tsironis hlist_bl_add_behind(&new_e->hash_list, &e->hash_list); 810f79ae415SNikos Tsironis } 811d74f81f8SMilan Broz } 812d74f81f8SMilan Broz 813a159c1acSJonathan Brassow /* 814a159c1acSJonathan Brassow * Callback used by the exception stores to load exceptions when 815a159c1acSJonathan Brassow * initialising. 816a159c1acSJonathan Brassow */ 817a159c1acSJonathan Brassow static int dm_add_exception(void *context, chunk_t old, chunk_t new) 8181da177e4SLinus Torvalds { 819f79ae415SNikos Tsironis struct dm_exception_table_lock lock; 820a159c1acSJonathan Brassow struct dm_snapshot *s = context; 8211d4989c8SJon Brassow struct dm_exception *e; 8221da177e4SLinus Torvalds 823119bc547SMikulas Patocka e = alloc_completed_exception(GFP_KERNEL); 8241da177e4SLinus Torvalds if (!e) 8251da177e4SLinus Torvalds return -ENOMEM; 8261da177e4SLinus Torvalds 8271da177e4SLinus Torvalds e->old_chunk = old; 828d74f81f8SMilan Broz 829d74f81f8SMilan Broz /* Consecutive_count is implicitly initialised to zero */ 8301da177e4SLinus Torvalds e->new_chunk = new; 831d74f81f8SMilan Broz 832f79ae415SNikos Tsironis /* 833f79ae415SNikos Tsironis * Although there is no need to lock access to the exception tables 834f79ae415SNikos Tsironis * here, if we don't then hlist_bl_add_head(), called by 835f79ae415SNikos Tsironis * dm_insert_exception(), will complain about accessing the 836f79ae415SNikos Tsironis * corresponding list without locking it first. 837f79ae415SNikos Tsironis */ 838f79ae415SNikos Tsironis dm_exception_table_lock_init(s, old, &lock); 839f79ae415SNikos Tsironis 840f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 8413510cb94SJon Brassow dm_insert_exception(&s->complete, e); 842f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 843d74f81f8SMilan Broz 8441da177e4SLinus Torvalds return 0; 8451da177e4SLinus Torvalds } 8461da177e4SLinus Torvalds 8477e201b35SMikulas Patocka /* 8487e201b35SMikulas Patocka * Return a minimum chunk size of all snapshots that have the specified origin. 8497e201b35SMikulas Patocka * Return zero if the origin has no snapshots. 8507e201b35SMikulas Patocka */ 851542f9038SMike Snitzer static uint32_t __minimum_chunk_size(struct origin *o) 8527e201b35SMikulas Patocka { 8537e201b35SMikulas Patocka struct dm_snapshot *snap; 85486a3238cSHeinz Mauelshagen unsigned int chunk_size = rounddown_pow_of_two(UINT_MAX); 8557e201b35SMikulas Patocka 8567e201b35SMikulas Patocka if (o) 8577e201b35SMikulas Patocka list_for_each_entry(snap, &o->snapshots, list) 858f16dba5dSMikulas Patocka chunk_size = min_not_zero(chunk_size, 859f16dba5dSMikulas Patocka snap->store->chunk_size); 8607e201b35SMikulas Patocka 861542f9038SMike Snitzer return (uint32_t) chunk_size; 8627e201b35SMikulas Patocka } 8637e201b35SMikulas Patocka 8641da177e4SLinus Torvalds /* 8651da177e4SLinus Torvalds * Hard coded magic. 8661da177e4SLinus Torvalds */ 8671da177e4SLinus Torvalds static int calc_max_buckets(void) 8681da177e4SLinus Torvalds { 8691da177e4SLinus Torvalds /* use a fixed size of 2MB */ 8701da177e4SLinus Torvalds unsigned long mem = 2 * 1024 * 1024; 871f79ae415SNikos Tsironis mem /= sizeof(struct hlist_bl_head); 8721da177e4SLinus Torvalds 8731da177e4SLinus Torvalds return mem; 8741da177e4SLinus Torvalds } 8751da177e4SLinus Torvalds 8761da177e4SLinus Torvalds /* 8771da177e4SLinus Torvalds * Allocate room for a suitable hash table. 8781da177e4SLinus Torvalds */ 879fee1998eSJonathan Brassow static int init_hash_tables(struct dm_snapshot *s) 8801da177e4SLinus Torvalds { 88160e356f3SMikulas Patocka sector_t hash_size, cow_dev_size, max_buckets; 8821da177e4SLinus Torvalds 8831da177e4SLinus Torvalds /* 8841da177e4SLinus Torvalds * Calculate based on the size of the original volume or 8851da177e4SLinus Torvalds * the COW volume... 8861da177e4SLinus Torvalds */ 887fc56f6fbSMike Snitzer cow_dev_size = get_dev_size(s->cow->bdev); 8881da177e4SLinus Torvalds max_buckets = calc_max_buckets(); 8891da177e4SLinus Torvalds 89060e356f3SMikulas Patocka hash_size = cow_dev_size >> s->store->chunk_shift; 8911da177e4SLinus Torvalds hash_size = min(hash_size, max_buckets); 8921da177e4SLinus Torvalds 8938e87b9b8SMikulas Patocka if (hash_size < 64) 8948e87b9b8SMikulas Patocka hash_size = 64; 8958defd830SRobert P. J. Day hash_size = rounddown_pow_of_two(hash_size); 8963510cb94SJon Brassow if (dm_exception_table_init(&s->complete, hash_size, 897d74f81f8SMilan Broz DM_CHUNK_CONSECUTIVE_BITS)) 8981da177e4SLinus Torvalds return -ENOMEM; 8991da177e4SLinus Torvalds 9001da177e4SLinus Torvalds /* 9011da177e4SLinus Torvalds * Allocate hash table for in-flight exceptions 9021da177e4SLinus Torvalds * Make this smaller than the real hash table 9031da177e4SLinus Torvalds */ 9041da177e4SLinus Torvalds hash_size >>= 3; 9051da177e4SLinus Torvalds if (hash_size < 64) 9061da177e4SLinus Torvalds hash_size = 64; 9071da177e4SLinus Torvalds 9083510cb94SJon Brassow if (dm_exception_table_init(&s->pending, hash_size, 0)) { 9093510cb94SJon Brassow dm_exception_table_exit(&s->complete, exception_cache); 9101da177e4SLinus Torvalds return -ENOMEM; 9111da177e4SLinus Torvalds } 9121da177e4SLinus Torvalds 9131da177e4SLinus Torvalds return 0; 9141da177e4SLinus Torvalds } 9151da177e4SLinus Torvalds 9161e03f97eSMikulas Patocka static void merge_shutdown(struct dm_snapshot *s) 9171e03f97eSMikulas Patocka { 9181e03f97eSMikulas Patocka clear_bit_unlock(RUNNING_MERGE, &s->state_bits); 9194e857c58SPeter Zijlstra smp_mb__after_atomic(); 9201e03f97eSMikulas Patocka wake_up_bit(&s->state_bits, RUNNING_MERGE); 9211e03f97eSMikulas Patocka } 9221e03f97eSMikulas Patocka 9239fe86254SMikulas Patocka static struct bio *__release_queued_bios_after_merge(struct dm_snapshot *s) 9249fe86254SMikulas Patocka { 9259fe86254SMikulas Patocka s->first_merging_chunk = 0; 9269fe86254SMikulas Patocka s->num_merging_chunks = 0; 9279fe86254SMikulas Patocka 9289fe86254SMikulas Patocka return bio_list_get(&s->bios_queued_during_merge); 9299fe86254SMikulas Patocka } 9309fe86254SMikulas Patocka 9311e03f97eSMikulas Patocka /* 9321e03f97eSMikulas Patocka * Remove one chunk from the index of completed exceptions. 9331e03f97eSMikulas Patocka */ 9341e03f97eSMikulas Patocka static int __remove_single_exception_chunk(struct dm_snapshot *s, 9351e03f97eSMikulas Patocka chunk_t old_chunk) 9361e03f97eSMikulas Patocka { 9371e03f97eSMikulas Patocka struct dm_exception *e; 9381e03f97eSMikulas Patocka 9391e03f97eSMikulas Patocka e = dm_lookup_exception(&s->complete, old_chunk); 9401e03f97eSMikulas Patocka if (!e) { 9411e03f97eSMikulas Patocka DMERR("Corruption detected: exception for block %llu is " 9421e03f97eSMikulas Patocka "on disk but not in memory", 9431e03f97eSMikulas Patocka (unsigned long long)old_chunk); 9441e03f97eSMikulas Patocka return -EINVAL; 9451e03f97eSMikulas Patocka } 9461e03f97eSMikulas Patocka 9471e03f97eSMikulas Patocka /* 9481e03f97eSMikulas Patocka * If this is the only chunk using this exception, remove exception. 9491e03f97eSMikulas Patocka */ 9501e03f97eSMikulas Patocka if (!dm_consecutive_chunk_count(e)) { 9511e03f97eSMikulas Patocka dm_remove_exception(e); 9521e03f97eSMikulas Patocka free_completed_exception(e); 9531e03f97eSMikulas Patocka return 0; 9541e03f97eSMikulas Patocka } 9551e03f97eSMikulas Patocka 9561e03f97eSMikulas Patocka /* 9571e03f97eSMikulas Patocka * The chunk may be either at the beginning or the end of a 9581e03f97eSMikulas Patocka * group of consecutive chunks - never in the middle. We are 9591e03f97eSMikulas Patocka * removing chunks in the opposite order to that in which they 9601e03f97eSMikulas Patocka * were added, so this should always be true. 9611e03f97eSMikulas Patocka * Decrement the consecutive chunk counter and adjust the 9621e03f97eSMikulas Patocka * starting point if necessary. 9631e03f97eSMikulas Patocka */ 9641e03f97eSMikulas Patocka if (old_chunk == e->old_chunk) { 9651e03f97eSMikulas Patocka e->old_chunk++; 9661e03f97eSMikulas Patocka e->new_chunk++; 9671e03f97eSMikulas Patocka } else if (old_chunk != e->old_chunk + 9681e03f97eSMikulas Patocka dm_consecutive_chunk_count(e)) { 9691e03f97eSMikulas Patocka DMERR("Attempt to merge block %llu from the " 9701e03f97eSMikulas Patocka "middle of a chunk range [%llu - %llu]", 9711e03f97eSMikulas Patocka (unsigned long long)old_chunk, 9721e03f97eSMikulas Patocka (unsigned long long)e->old_chunk, 9731e03f97eSMikulas Patocka (unsigned long long) 9741e03f97eSMikulas Patocka e->old_chunk + dm_consecutive_chunk_count(e)); 9751e03f97eSMikulas Patocka return -EINVAL; 9761e03f97eSMikulas Patocka } 9771e03f97eSMikulas Patocka 9781e03f97eSMikulas Patocka dm_consecutive_chunk_count_dec(e); 9791e03f97eSMikulas Patocka 9801e03f97eSMikulas Patocka return 0; 9811e03f97eSMikulas Patocka } 9821e03f97eSMikulas Patocka 9839fe86254SMikulas Patocka static void flush_bios(struct bio *bio); 9849fe86254SMikulas Patocka 9859fe86254SMikulas Patocka static int remove_single_exception_chunk(struct dm_snapshot *s) 9861e03f97eSMikulas Patocka { 9879fe86254SMikulas Patocka struct bio *b = NULL; 9889fe86254SMikulas Patocka int r; 9899fe86254SMikulas Patocka chunk_t old_chunk = s->first_merging_chunk + s->num_merging_chunks - 1; 9901e03f97eSMikulas Patocka 9914ad8d880SNikos Tsironis down_write(&s->lock); 9929fe86254SMikulas Patocka 9939fe86254SMikulas Patocka /* 9949fe86254SMikulas Patocka * Process chunks (and associated exceptions) in reverse order 9959fe86254SMikulas Patocka * so that dm_consecutive_chunk_count_dec() accounting works. 9969fe86254SMikulas Patocka */ 9979fe86254SMikulas Patocka do { 9981e03f97eSMikulas Patocka r = __remove_single_exception_chunk(s, old_chunk); 9999fe86254SMikulas Patocka if (r) 10009fe86254SMikulas Patocka goto out; 10019fe86254SMikulas Patocka } while (old_chunk-- > s->first_merging_chunk); 10029fe86254SMikulas Patocka 10039fe86254SMikulas Patocka b = __release_queued_bios_after_merge(s); 10049fe86254SMikulas Patocka 10059fe86254SMikulas Patocka out: 10064ad8d880SNikos Tsironis up_write(&s->lock); 10079fe86254SMikulas Patocka if (b) 10089fe86254SMikulas Patocka flush_bios(b); 10091e03f97eSMikulas Patocka 10101e03f97eSMikulas Patocka return r; 10111e03f97eSMikulas Patocka } 10121e03f97eSMikulas Patocka 101373dfd078SMikulas Patocka static int origin_write_extent(struct dm_snapshot *merging_snap, 101486a3238cSHeinz Mauelshagen sector_t sector, unsigned int chunk_size); 101573dfd078SMikulas Patocka 10161e03f97eSMikulas Patocka static void merge_callback(int read_err, unsigned long write_err, 10171e03f97eSMikulas Patocka void *context); 10181e03f97eSMikulas Patocka 101973dfd078SMikulas Patocka static uint64_t read_pending_exceptions_done_count(void) 102073dfd078SMikulas Patocka { 102173dfd078SMikulas Patocka uint64_t pending_exceptions_done; 102273dfd078SMikulas Patocka 102373dfd078SMikulas Patocka spin_lock(&_pending_exceptions_done_spinlock); 102473dfd078SMikulas Patocka pending_exceptions_done = _pending_exceptions_done_count; 102573dfd078SMikulas Patocka spin_unlock(&_pending_exceptions_done_spinlock); 102673dfd078SMikulas Patocka 102773dfd078SMikulas Patocka return pending_exceptions_done; 102873dfd078SMikulas Patocka } 102973dfd078SMikulas Patocka 103073dfd078SMikulas Patocka static void increment_pending_exceptions_done_count(void) 103173dfd078SMikulas Patocka { 103273dfd078SMikulas Patocka spin_lock(&_pending_exceptions_done_spinlock); 103373dfd078SMikulas Patocka _pending_exceptions_done_count++; 103473dfd078SMikulas Patocka spin_unlock(&_pending_exceptions_done_spinlock); 103573dfd078SMikulas Patocka 103673dfd078SMikulas Patocka wake_up_all(&_pending_exceptions_done); 103773dfd078SMikulas Patocka } 103873dfd078SMikulas Patocka 10391e03f97eSMikulas Patocka static void snapshot_merge_next_chunks(struct dm_snapshot *s) 10401e03f97eSMikulas Patocka { 10418a2d5286SMike Snitzer int i, linear_chunks; 10421e03f97eSMikulas Patocka chunk_t old_chunk, new_chunk; 10431e03f97eSMikulas Patocka struct dm_io_region src, dest; 10448a2d5286SMike Snitzer sector_t io_size; 104573dfd078SMikulas Patocka uint64_t previous_count; 10461e03f97eSMikulas Patocka 10471e03f97eSMikulas Patocka BUG_ON(!test_bit(RUNNING_MERGE, &s->state_bits)); 10481e03f97eSMikulas Patocka if (unlikely(test_bit(SHUTDOWN_MERGE, &s->state_bits))) 10491e03f97eSMikulas Patocka goto shut; 10501e03f97eSMikulas Patocka 10511e03f97eSMikulas Patocka /* 10521e03f97eSMikulas Patocka * valid flag never changes during merge, so no lock required. 10531e03f97eSMikulas Patocka */ 10541e03f97eSMikulas Patocka if (!s->valid) { 10551e03f97eSMikulas Patocka DMERR("Snapshot is invalid: can't merge"); 10561e03f97eSMikulas Patocka goto shut; 10571e03f97eSMikulas Patocka } 10581e03f97eSMikulas Patocka 10598a2d5286SMike Snitzer linear_chunks = s->store->type->prepare_merge(s->store, &old_chunk, 10608a2d5286SMike Snitzer &new_chunk); 10618a2d5286SMike Snitzer if (linear_chunks <= 0) { 1062d8ddb1cfSMike Snitzer if (linear_chunks < 0) { 10631e03f97eSMikulas Patocka DMERR("Read error in exception store: " 10641e03f97eSMikulas Patocka "shutting down merge"); 10654ad8d880SNikos Tsironis down_write(&s->lock); 10661d1dda8cSzhengbin s->merge_failed = true; 10674ad8d880SNikos Tsironis up_write(&s->lock); 1068d8ddb1cfSMike Snitzer } 10691e03f97eSMikulas Patocka goto shut; 10701e03f97eSMikulas Patocka } 10711e03f97eSMikulas Patocka 10728a2d5286SMike Snitzer /* Adjust old_chunk and new_chunk to reflect start of linear region */ 10738a2d5286SMike Snitzer old_chunk = old_chunk + 1 - linear_chunks; 10748a2d5286SMike Snitzer new_chunk = new_chunk + 1 - linear_chunks; 10758a2d5286SMike Snitzer 10768a2d5286SMike Snitzer /* 10778a2d5286SMike Snitzer * Use one (potentially large) I/O to copy all 'linear_chunks' 10788a2d5286SMike Snitzer * from the exception store to the origin 10798a2d5286SMike Snitzer */ 10808a2d5286SMike Snitzer io_size = linear_chunks * s->store->chunk_size; 10811e03f97eSMikulas Patocka 10821e03f97eSMikulas Patocka dest.bdev = s->origin->bdev; 10831e03f97eSMikulas Patocka dest.sector = chunk_to_sector(s->store, old_chunk); 10848a2d5286SMike Snitzer dest.count = min(io_size, get_dev_size(dest.bdev) - dest.sector); 10851e03f97eSMikulas Patocka 10861e03f97eSMikulas Patocka src.bdev = s->cow->bdev; 10871e03f97eSMikulas Patocka src.sector = chunk_to_sector(s->store, new_chunk); 10881e03f97eSMikulas Patocka src.count = dest.count; 10891e03f97eSMikulas Patocka 109073dfd078SMikulas Patocka /* 109173dfd078SMikulas Patocka * Reallocate any exceptions needed in other snapshots then 109273dfd078SMikulas Patocka * wait for the pending exceptions to complete. 109373dfd078SMikulas Patocka * Each time any pending exception (globally on the system) 109473dfd078SMikulas Patocka * completes we are woken and repeat the process to find out 109573dfd078SMikulas Patocka * if we can proceed. While this may not seem a particularly 109673dfd078SMikulas Patocka * efficient algorithm, it is not expected to have any 109773dfd078SMikulas Patocka * significant impact on performance. 109873dfd078SMikulas Patocka */ 109973dfd078SMikulas Patocka previous_count = read_pending_exceptions_done_count(); 11008a2d5286SMike Snitzer while (origin_write_extent(s, dest.sector, io_size)) { 110173dfd078SMikulas Patocka wait_event(_pending_exceptions_done, 110273dfd078SMikulas Patocka (read_pending_exceptions_done_count() != 110373dfd078SMikulas Patocka previous_count)); 110473dfd078SMikulas Patocka /* Retry after the wait, until all exceptions are done. */ 110573dfd078SMikulas Patocka previous_count = read_pending_exceptions_done_count(); 110673dfd078SMikulas Patocka } 110773dfd078SMikulas Patocka 11084ad8d880SNikos Tsironis down_write(&s->lock); 11099fe86254SMikulas Patocka s->first_merging_chunk = old_chunk; 11108a2d5286SMike Snitzer s->num_merging_chunks = linear_chunks; 11114ad8d880SNikos Tsironis up_write(&s->lock); 11129fe86254SMikulas Patocka 11138a2d5286SMike Snitzer /* Wait until writes to all 'linear_chunks' drain */ 11148a2d5286SMike Snitzer for (i = 0; i < linear_chunks; i++) 11158a2d5286SMike Snitzer __check_for_conflicting_io(s, old_chunk + i); 11169fe86254SMikulas Patocka 11171e03f97eSMikulas Patocka dm_kcopyd_copy(s->kcopyd_client, &src, 1, &dest, 0, merge_callback, s); 11181e03f97eSMikulas Patocka return; 11191e03f97eSMikulas Patocka 11201e03f97eSMikulas Patocka shut: 11211e03f97eSMikulas Patocka merge_shutdown(s); 11221e03f97eSMikulas Patocka } 11231e03f97eSMikulas Patocka 11249fe86254SMikulas Patocka static void error_bios(struct bio *bio); 11259fe86254SMikulas Patocka 11261e03f97eSMikulas Patocka static void merge_callback(int read_err, unsigned long write_err, void *context) 11271e03f97eSMikulas Patocka { 11281e03f97eSMikulas Patocka struct dm_snapshot *s = context; 11299fe86254SMikulas Patocka struct bio *b = NULL; 11301e03f97eSMikulas Patocka 11311e03f97eSMikulas Patocka if (read_err || write_err) { 11321e03f97eSMikulas Patocka if (read_err) 11331e03f97eSMikulas Patocka DMERR("Read error: shutting down merge."); 11341e03f97eSMikulas Patocka else 11351e03f97eSMikulas Patocka DMERR("Write error: shutting down merge."); 11361e03f97eSMikulas Patocka goto shut; 11371e03f97eSMikulas Patocka } 11381e03f97eSMikulas Patocka 1139eba33b8eSChristoph Hellwig if (blkdev_issue_flush(s->origin->bdev) < 0) { 1140fcc42338SAkilesh Kailash DMERR("Flush after merge failed: shutting down merge"); 1141fcc42338SAkilesh Kailash goto shut; 1142fcc42338SAkilesh Kailash } 1143fcc42338SAkilesh Kailash 11449fe86254SMikulas Patocka if (s->store->type->commit_merge(s->store, 11459fe86254SMikulas Patocka s->num_merging_chunks) < 0) { 11461e03f97eSMikulas Patocka DMERR("Write error in exception store: shutting down merge"); 11471e03f97eSMikulas Patocka goto shut; 11481e03f97eSMikulas Patocka } 11491e03f97eSMikulas Patocka 11509fe86254SMikulas Patocka if (remove_single_exception_chunk(s) < 0) 11519fe86254SMikulas Patocka goto shut; 11529fe86254SMikulas Patocka 11531e03f97eSMikulas Patocka snapshot_merge_next_chunks(s); 11541e03f97eSMikulas Patocka 11551e03f97eSMikulas Patocka return; 11561e03f97eSMikulas Patocka 11571e03f97eSMikulas Patocka shut: 11584ad8d880SNikos Tsironis down_write(&s->lock); 11591d1dda8cSzhengbin s->merge_failed = true; 11609fe86254SMikulas Patocka b = __release_queued_bios_after_merge(s); 11614ad8d880SNikos Tsironis up_write(&s->lock); 11629fe86254SMikulas Patocka error_bios(b); 11639fe86254SMikulas Patocka 11641e03f97eSMikulas Patocka merge_shutdown(s); 11651e03f97eSMikulas Patocka } 11661e03f97eSMikulas Patocka 11671e03f97eSMikulas Patocka static void start_merge(struct dm_snapshot *s) 11681e03f97eSMikulas Patocka { 11691e03f97eSMikulas Patocka if (!test_and_set_bit(RUNNING_MERGE, &s->state_bits)) 11701e03f97eSMikulas Patocka snapshot_merge_next_chunks(s); 11711e03f97eSMikulas Patocka } 11721e03f97eSMikulas Patocka 11731e03f97eSMikulas Patocka /* 11741e03f97eSMikulas Patocka * Stop the merging process and wait until it finishes. 11751e03f97eSMikulas Patocka */ 11761e03f97eSMikulas Patocka static void stop_merge(struct dm_snapshot *s) 11771e03f97eSMikulas Patocka { 11781e03f97eSMikulas Patocka set_bit(SHUTDOWN_MERGE, &s->state_bits); 117974316201SNeilBrown wait_on_bit(&s->state_bits, RUNNING_MERGE, TASK_UNINTERRUPTIBLE); 11801e03f97eSMikulas Patocka clear_bit(SHUTDOWN_MERGE, &s->state_bits); 11811e03f97eSMikulas Patocka } 11821e03f97eSMikulas Patocka 11832e602385SMike Snitzer static int parse_snapshot_features(struct dm_arg_set *as, struct dm_snapshot *s, 11842e602385SMike Snitzer struct dm_target *ti) 11852e602385SMike Snitzer { 11862e602385SMike Snitzer int r; 118786a3238cSHeinz Mauelshagen unsigned int argc; 11882e602385SMike Snitzer const char *arg_name; 11892e602385SMike Snitzer 11902e602385SMike Snitzer static const struct dm_arg _args[] = { 11912e602385SMike Snitzer {0, 2, "Invalid number of feature arguments"}, 11922e602385SMike Snitzer }; 11932e602385SMike Snitzer 11941da177e4SLinus Torvalds /* 11952e602385SMike Snitzer * No feature arguments supplied. 11962e602385SMike Snitzer */ 11972e602385SMike Snitzer if (!as->argc) 11982e602385SMike Snitzer return 0; 11992e602385SMike Snitzer 12002e602385SMike Snitzer r = dm_read_arg_group(_args, as, &argc, &ti->error); 12012e602385SMike Snitzer if (r) 12022e602385SMike Snitzer return -EINVAL; 12032e602385SMike Snitzer 12042e602385SMike Snitzer while (argc && !r) { 12052e602385SMike Snitzer arg_name = dm_shift_arg(as); 12062e602385SMike Snitzer argc--; 12072e602385SMike Snitzer 12082e602385SMike Snitzer if (!strcasecmp(arg_name, "discard_zeroes_cow")) 12092e602385SMike Snitzer s->discard_zeroes_cow = true; 12102e602385SMike Snitzer 12112e602385SMike Snitzer else if (!strcasecmp(arg_name, "discard_passdown_origin")) 12122e602385SMike Snitzer s->discard_passdown_origin = true; 12132e602385SMike Snitzer 12142e602385SMike Snitzer else { 12152e602385SMike Snitzer ti->error = "Unrecognised feature requested"; 12162e602385SMike Snitzer r = -EINVAL; 12172e602385SMike Snitzer break; 12182e602385SMike Snitzer } 12192e602385SMike Snitzer } 12202e602385SMike Snitzer 12212e602385SMike Snitzer if (!s->discard_zeroes_cow && s->discard_passdown_origin) { 12222e602385SMike Snitzer /* 12232e602385SMike Snitzer * TODO: really these are disjoint.. but ti->num_discard_bios 12242e602385SMike Snitzer * and dm_bio_get_target_bio_nr() require rigid constraints. 12252e602385SMike Snitzer */ 12262e602385SMike Snitzer ti->error = "discard_passdown_origin feature depends on discard_zeroes_cow"; 12272e602385SMike Snitzer r = -EINVAL; 12282e602385SMike Snitzer } 12292e602385SMike Snitzer 12302e602385SMike Snitzer return r; 12312e602385SMike Snitzer } 12322e602385SMike Snitzer 12332e602385SMike Snitzer /* 12342e602385SMike Snitzer * Construct a snapshot mapping: 12352e602385SMike Snitzer * <origin_dev> <COW-dev> <p|po|n> <chunk-size> [<# feature args> [<arg>]*] 12361da177e4SLinus Torvalds */ 12371da177e4SLinus Torvalds static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv) 12381da177e4SLinus Torvalds { 12391da177e4SLinus Torvalds struct dm_snapshot *s; 12402e602385SMike Snitzer struct dm_arg_set as; 1241cd45daffSMikulas Patocka int i; 12421da177e4SLinus Torvalds int r = -EINVAL; 1243fc56f6fbSMike Snitzer char *origin_path, *cow_path; 12444df2bf46SDingXiang dev_t origin_dev, cow_dev; 124586a3238cSHeinz Mauelshagen unsigned int args_used, num_flush_bios = 1; 124610b8106aSMike Snitzer fmode_t origin_mode = FMODE_READ; 12471da177e4SLinus Torvalds 12482e602385SMike Snitzer if (argc < 4) { 12492e602385SMike Snitzer ti->error = "requires 4 or more arguments"; 12501da177e4SLinus Torvalds r = -EINVAL; 1251fc56f6fbSMike Snitzer goto bad; 12521da177e4SLinus Torvalds } 12531da177e4SLinus Torvalds 125410b8106aSMike Snitzer if (dm_target_is_snapshot_merge(ti)) { 125555a62eefSAlasdair G Kergon num_flush_bios = 2; 125610b8106aSMike Snitzer origin_mode = FMODE_WRITE; 125710b8106aSMike Snitzer } 125810b8106aSMike Snitzer 1259d3775354SKent Overstreet s = kzalloc(sizeof(*s), GFP_KERNEL); 1260fee1998eSJonathan Brassow if (!s) { 1261a2d2b034SJonathan Brassow ti->error = "Cannot allocate private snapshot structure"; 12621da177e4SLinus Torvalds r = -ENOMEM; 1263fc56f6fbSMike Snitzer goto bad; 12641da177e4SLinus Torvalds } 12651da177e4SLinus Torvalds 12662e602385SMike Snitzer as.argc = argc; 12672e602385SMike Snitzer as.argv = argv; 12682e602385SMike Snitzer dm_consume_args(&as, 4); 12692e602385SMike Snitzer r = parse_snapshot_features(&as, s, ti); 12702e602385SMike Snitzer if (r) 12712e602385SMike Snitzer goto bad_features; 12722e602385SMike Snitzer 1273c2411045SMikulas Patocka origin_path = argv[0]; 1274c2411045SMikulas Patocka argv++; 1275c2411045SMikulas Patocka argc--; 1276c2411045SMikulas Patocka 1277c2411045SMikulas Patocka r = dm_get_device(ti, origin_path, origin_mode, &s->origin); 1278c2411045SMikulas Patocka if (r) { 1279c2411045SMikulas Patocka ti->error = "Cannot get origin device"; 1280c2411045SMikulas Patocka goto bad_origin; 1281c2411045SMikulas Patocka } 12824df2bf46SDingXiang origin_dev = s->origin->bdev->bd_dev; 1283c2411045SMikulas Patocka 1284fc56f6fbSMike Snitzer cow_path = argv[0]; 1285fc56f6fbSMike Snitzer argv++; 1286fc56f6fbSMike Snitzer argc--; 1287fc56f6fbSMike Snitzer 12884df2bf46SDingXiang cow_dev = dm_get_dev_t(cow_path); 12894df2bf46SDingXiang if (cow_dev && cow_dev == origin_dev) { 12904df2bf46SDingXiang ti->error = "COW device cannot be the same as origin device"; 12914df2bf46SDingXiang r = -EINVAL; 12924df2bf46SDingXiang goto bad_cow; 12934df2bf46SDingXiang } 12944df2bf46SDingXiang 1295024d37e9SMilan Broz r = dm_get_device(ti, cow_path, dm_table_get_mode(ti->table), &s->cow); 1296fc56f6fbSMike Snitzer if (r) { 1297fc56f6fbSMike Snitzer ti->error = "Cannot get COW device"; 1298fc56f6fbSMike Snitzer goto bad_cow; 1299fc56f6fbSMike Snitzer } 1300fc56f6fbSMike Snitzer 1301fc56f6fbSMike Snitzer r = dm_exception_store_create(ti, argc, argv, s, &args_used, &s->store); 1302fc56f6fbSMike Snitzer if (r) { 1303fc56f6fbSMike Snitzer ti->error = "Couldn't create exception store"; 1304fc56f6fbSMike Snitzer r = -EINVAL; 1305fc56f6fbSMike Snitzer goto bad_store; 1306fc56f6fbSMike Snitzer } 1307fc56f6fbSMike Snitzer 1308fc56f6fbSMike Snitzer argv += args_used; 1309fc56f6fbSMike Snitzer argc -= args_used; 1310fc56f6fbSMike Snitzer 1311fc56f6fbSMike Snitzer s->ti = ti; 13121da177e4SLinus Torvalds s->valid = 1; 131376c44f6dSMikulas Patocka s->snapshot_overflowed = 0; 1314aa14edebSAlasdair G Kergon s->active = 0; 1315879129d2SMikulas Patocka atomic_set(&s->pending_exceptions_count, 0); 13163f1637f2SNikos Tsironis spin_lock_init(&s->pe_allocation_lock); 1317230c83afSMikulas Patocka s->exception_start_sequence = 0; 1318230c83afSMikulas Patocka s->exception_complete_sequence = 0; 13193db2776dSDavid Jeffery s->out_of_order_tree = RB_ROOT; 13204ad8d880SNikos Tsironis init_rwsem(&s->lock); 1321c1f0c183SMike Snitzer INIT_LIST_HEAD(&s->list); 1322ca3a931fSAlasdair G Kergon spin_lock_init(&s->pe_lock); 13231e03f97eSMikulas Patocka s->state_bits = 0; 13241d1dda8cSzhengbin s->merge_failed = false; 13259fe86254SMikulas Patocka s->first_merging_chunk = 0; 13269fe86254SMikulas Patocka s->num_merging_chunks = 0; 13279fe86254SMikulas Patocka bio_list_init(&s->bios_queued_during_merge); 13281da177e4SLinus Torvalds 13291da177e4SLinus Torvalds /* Allocate hash table for COW data */ 1330fee1998eSJonathan Brassow if (init_hash_tables(s)) { 13311da177e4SLinus Torvalds ti->error = "Unable to allocate hash table space"; 13321da177e4SLinus Torvalds r = -ENOMEM; 1333fee1998eSJonathan Brassow goto bad_hash_tables; 13341da177e4SLinus Torvalds } 13351da177e4SLinus Torvalds 1336b2155578SMikulas Patocka init_waitqueue_head(&s->in_progress_wait); 1337721b1d98SNikos Tsironis 1338df5d2e90SMikulas Patocka s->kcopyd_client = dm_kcopyd_client_create(&dm_kcopyd_throttle); 1339fa34ce73SMikulas Patocka if (IS_ERR(s->kcopyd_client)) { 1340fa34ce73SMikulas Patocka r = PTR_ERR(s->kcopyd_client); 13411da177e4SLinus Torvalds ti->error = "Could not create kcopyd client"; 1342fee1998eSJonathan Brassow goto bad_kcopyd; 13431da177e4SLinus Torvalds } 13441da177e4SLinus Torvalds 13456f1c819cSKent Overstreet r = mempool_init_slab_pool(&s->pending_pool, MIN_IOS, pending_cache); 13466f1c819cSKent Overstreet if (r) { 134792e86812SMikulas Patocka ti->error = "Could not allocate mempool for pending exceptions"; 1348fee1998eSJonathan Brassow goto bad_pending_pool; 134992e86812SMikulas Patocka } 135092e86812SMikulas Patocka 1351cd45daffSMikulas Patocka for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) 1352cd45daffSMikulas Patocka INIT_HLIST_HEAD(&s->tracked_chunk_hash[i]); 1353cd45daffSMikulas Patocka 1354cd45daffSMikulas Patocka spin_lock_init(&s->tracked_chunk_lock); 1355cd45daffSMikulas Patocka 1356c1f0c183SMike Snitzer ti->private = s; 135755a62eefSAlasdair G Kergon ti->num_flush_bios = num_flush_bios; 13582e602385SMike Snitzer if (s->discard_zeroes_cow) 13592e602385SMike Snitzer ti->num_discard_bios = (s->discard_passdown_origin ? 2 : 1); 136030187e1dSMike Snitzer ti->per_io_data_size = sizeof(struct dm_snap_tracked_chunk); 1361c1f0c183SMike Snitzer 1362c1f0c183SMike Snitzer /* Add snapshot to the list of snapshots for this origin */ 1363c1f0c183SMike Snitzer /* Exceptions aren't triggered till snapshot_resume() is called */ 1364c1f0c183SMike Snitzer r = register_snapshot(s); 1365c1f0c183SMike Snitzer if (r == -ENOMEM) { 1366c1f0c183SMike Snitzer ti->error = "Snapshot origin struct allocation failed"; 1367c1f0c183SMike Snitzer goto bad_load_and_register; 1368c1f0c183SMike Snitzer } else if (r < 0) { 1369c1f0c183SMike Snitzer /* invalid handover, register_snapshot has set ti->error */ 1370c1f0c183SMike Snitzer goto bad_load_and_register; 1371c1f0c183SMike Snitzer } 1372c1f0c183SMike Snitzer 1373c1f0c183SMike Snitzer /* 1374c1f0c183SMike Snitzer * Metadata must only be loaded into one table at once, so skip this 1375c1f0c183SMike Snitzer * if metadata will be handed over during resume. 1376c1f0c183SMike Snitzer * Chunk size will be set during the handover - set it to zero to 1377c1f0c183SMike Snitzer * ensure it's ignored. 1378c1f0c183SMike Snitzer */ 1379c1f0c183SMike Snitzer if (r > 0) { 1380c1f0c183SMike Snitzer s->store->chunk_size = 0; 1381c1f0c183SMike Snitzer return 0; 1382c1f0c183SMike Snitzer } 1383c1f0c183SMike Snitzer 1384493df71cSJonathan Brassow r = s->store->type->read_metadata(s->store, dm_add_exception, 1385493df71cSJonathan Brassow (void *)s); 13860764147bSMilan Broz if (r < 0) { 1387f9cea4f7SMark McLoughlin ti->error = "Failed to read snapshot metadata"; 1388c1f0c183SMike Snitzer goto bad_read_metadata; 13890764147bSMilan Broz } else if (r > 0) { 13900764147bSMilan Broz s->valid = 0; 13910764147bSMilan Broz DMWARN("Snapshot is marked invalid."); 1392f9cea4f7SMark McLoughlin } 1393aa14edebSAlasdair G Kergon 13943f2412dcSMikulas Patocka if (!s->store->chunk_size) { 13953f2412dcSMikulas Patocka ti->error = "Chunk size not set"; 1396c699a0dbSMikulas Patocka r = -EINVAL; 1397c1f0c183SMike Snitzer goto bad_read_metadata; 13983f2412dcSMikulas Patocka } 1399542f9038SMike Snitzer 1400542f9038SMike Snitzer r = dm_set_target_max_io_len(ti, s->store->chunk_size); 1401542f9038SMike Snitzer if (r) 1402542f9038SMike Snitzer goto bad_read_metadata; 14031da177e4SLinus Torvalds 14041da177e4SLinus Torvalds return 0; 14051da177e4SLinus Torvalds 1406c1f0c183SMike Snitzer bad_read_metadata: 1407c1f0c183SMike Snitzer unregister_snapshot(s); 1408cd45daffSMikulas Patocka bad_load_and_register: 14096f1c819cSKent Overstreet mempool_exit(&s->pending_pool); 1410fee1998eSJonathan Brassow bad_pending_pool: 1411eb69aca5SHeinz Mauelshagen dm_kcopyd_client_destroy(s->kcopyd_client); 1412fee1998eSJonathan Brassow bad_kcopyd: 14133510cb94SJon Brassow dm_exception_table_exit(&s->pending, pending_cache); 14143510cb94SJon Brassow dm_exception_table_exit(&s->complete, exception_cache); 1415fee1998eSJonathan Brassow bad_hash_tables: 1416fc56f6fbSMike Snitzer dm_exception_store_destroy(s->store); 1417fc56f6fbSMike Snitzer bad_store: 1418fc56f6fbSMike Snitzer dm_put_device(ti, s->cow); 1419fc56f6fbSMike Snitzer bad_cow: 1420c2411045SMikulas Patocka dm_put_device(ti, s->origin); 1421c2411045SMikulas Patocka bad_origin: 14222e602385SMike Snitzer bad_features: 14231da177e4SLinus Torvalds kfree(s); 1424fc56f6fbSMike Snitzer bad: 14251da177e4SLinus Torvalds return r; 14261da177e4SLinus Torvalds } 14271da177e4SLinus Torvalds 142831c93a0cSMilan Broz static void __free_exceptions(struct dm_snapshot *s) 142931c93a0cSMilan Broz { 1430eb69aca5SHeinz Mauelshagen dm_kcopyd_client_destroy(s->kcopyd_client); 143131c93a0cSMilan Broz s->kcopyd_client = NULL; 143231c93a0cSMilan Broz 14333510cb94SJon Brassow dm_exception_table_exit(&s->pending, pending_cache); 14343510cb94SJon Brassow dm_exception_table_exit(&s->complete, exception_cache); 143531c93a0cSMilan Broz } 143631c93a0cSMilan Broz 1437c1f0c183SMike Snitzer static void __handover_exceptions(struct dm_snapshot *snap_src, 1438c1f0c183SMike Snitzer struct dm_snapshot *snap_dest) 1439c1f0c183SMike Snitzer { 1440c1f0c183SMike Snitzer union { 1441c1f0c183SMike Snitzer struct dm_exception_table table_swap; 1442c1f0c183SMike Snitzer struct dm_exception_store *store_swap; 1443c1f0c183SMike Snitzer } u; 1444c1f0c183SMike Snitzer 1445c1f0c183SMike Snitzer /* 1446c1f0c183SMike Snitzer * Swap all snapshot context information between the two instances. 1447c1f0c183SMike Snitzer */ 1448c1f0c183SMike Snitzer u.table_swap = snap_dest->complete; 1449c1f0c183SMike Snitzer snap_dest->complete = snap_src->complete; 1450c1f0c183SMike Snitzer snap_src->complete = u.table_swap; 1451c1f0c183SMike Snitzer 1452c1f0c183SMike Snitzer u.store_swap = snap_dest->store; 1453c1f0c183SMike Snitzer snap_dest->store = snap_src->store; 1454b0d3cc01SMike Snitzer snap_dest->store->userspace_supports_overflow = u.store_swap->userspace_supports_overflow; 1455c1f0c183SMike Snitzer snap_src->store = u.store_swap; 1456c1f0c183SMike Snitzer 1457c1f0c183SMike Snitzer snap_dest->store->snap = snap_dest; 1458c1f0c183SMike Snitzer snap_src->store->snap = snap_src; 1459c1f0c183SMike Snitzer 1460542f9038SMike Snitzer snap_dest->ti->max_io_len = snap_dest->store->chunk_size; 1461c1f0c183SMike Snitzer snap_dest->valid = snap_src->valid; 146276c44f6dSMikulas Patocka snap_dest->snapshot_overflowed = snap_src->snapshot_overflowed; 1463c1f0c183SMike Snitzer 1464c1f0c183SMike Snitzer /* 1465c1f0c183SMike Snitzer * Set source invalid to ensure it receives no further I/O. 1466c1f0c183SMike Snitzer */ 1467c1f0c183SMike Snitzer snap_src->valid = 0; 1468c1f0c183SMike Snitzer } 1469c1f0c183SMike Snitzer 14701da177e4SLinus Torvalds static void snapshot_dtr(struct dm_target *ti) 14711da177e4SLinus Torvalds { 1472cd45daffSMikulas Patocka #ifdef CONFIG_DM_DEBUG 1473cd45daffSMikulas Patocka int i; 1474cd45daffSMikulas Patocka #endif 1475028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 1476c1f0c183SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 14771da177e4SLinus Torvalds 1478c1f0c183SMike Snitzer down_read(&_origins_lock); 1479c1f0c183SMike Snitzer /* Check whether exception handover must be cancelled */ 14809d3b15c4SMikulas Patocka (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); 1481c1f0c183SMike Snitzer if (snap_src && snap_dest && (s == snap_src)) { 14824ad8d880SNikos Tsironis down_write(&snap_dest->lock); 1483c1f0c183SMike Snitzer snap_dest->valid = 0; 14844ad8d880SNikos Tsironis up_write(&snap_dest->lock); 1485c1f0c183SMike Snitzer DMERR("Cancelling snapshot handover."); 1486c1f0c183SMike Snitzer } 1487c1f0c183SMike Snitzer up_read(&_origins_lock); 1488c1f0c183SMike Snitzer 14891e03f97eSMikulas Patocka if (dm_target_is_snapshot_merge(ti)) 14901e03f97eSMikulas Patocka stop_merge(s); 14911e03f97eSMikulas Patocka 1492138728dcSAlasdair G Kergon /* Prevent further origin writes from using this snapshot. */ 1493138728dcSAlasdair G Kergon /* After this returns there can be no new kcopyd jobs. */ 14941da177e4SLinus Torvalds unregister_snapshot(s); 14951da177e4SLinus Torvalds 1496879129d2SMikulas Patocka while (atomic_read(&s->pending_exceptions_count)) 1497238d991fSHeinz Mauelshagen fsleep(1000); 1498879129d2SMikulas Patocka /* 14996f1c819cSKent Overstreet * Ensure instructions in mempool_exit aren't reordered 1500879129d2SMikulas Patocka * before atomic_read. 1501879129d2SMikulas Patocka */ 1502879129d2SMikulas Patocka smp_mb(); 1503879129d2SMikulas Patocka 1504cd45daffSMikulas Patocka #ifdef CONFIG_DM_DEBUG 1505cd45daffSMikulas Patocka for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) 1506cd45daffSMikulas Patocka BUG_ON(!hlist_empty(&s->tracked_chunk_hash[i])); 1507cd45daffSMikulas Patocka #endif 1508cd45daffSMikulas Patocka 150931c93a0cSMilan Broz __free_exceptions(s); 15101da177e4SLinus Torvalds 15116f1c819cSKent Overstreet mempool_exit(&s->pending_pool); 151292e86812SMikulas Patocka 1513fee1998eSJonathan Brassow dm_exception_store_destroy(s->store); 1514138728dcSAlasdair G Kergon 1515fc56f6fbSMike Snitzer dm_put_device(ti, s->cow); 1516fc56f6fbSMike Snitzer 1517c2411045SMikulas Patocka dm_put_device(ti, s->origin); 1518c2411045SMikulas Patocka 1519b2155578SMikulas Patocka WARN_ON(s->in_progress); 1520b2155578SMikulas Patocka 15211da177e4SLinus Torvalds kfree(s); 15221da177e4SLinus Torvalds } 15231da177e4SLinus Torvalds 1524a2f83e8bSMikulas Patocka static void account_start_copy(struct dm_snapshot *s) 1525a2f83e8bSMikulas Patocka { 1526b2155578SMikulas Patocka spin_lock(&s->in_progress_wait.lock); 1527b2155578SMikulas Patocka s->in_progress++; 1528b2155578SMikulas Patocka spin_unlock(&s->in_progress_wait.lock); 1529a2f83e8bSMikulas Patocka } 1530a2f83e8bSMikulas Patocka 1531a2f83e8bSMikulas Patocka static void account_end_copy(struct dm_snapshot *s) 1532a2f83e8bSMikulas Patocka { 1533b2155578SMikulas Patocka spin_lock(&s->in_progress_wait.lock); 1534b2155578SMikulas Patocka BUG_ON(!s->in_progress); 1535b2155578SMikulas Patocka s->in_progress--; 1536b2155578SMikulas Patocka if (likely(s->in_progress <= cow_threshold) && 1537b2155578SMikulas Patocka unlikely(waitqueue_active(&s->in_progress_wait))) 1538b2155578SMikulas Patocka wake_up_locked(&s->in_progress_wait); 1539b2155578SMikulas Patocka spin_unlock(&s->in_progress_wait.lock); 1540b2155578SMikulas Patocka } 1541b2155578SMikulas Patocka 1542b2155578SMikulas Patocka static bool wait_for_in_progress(struct dm_snapshot *s, bool unlock_origins) 1543b2155578SMikulas Patocka { 1544b2155578SMikulas Patocka if (unlikely(s->in_progress > cow_threshold)) { 1545b2155578SMikulas Patocka spin_lock(&s->in_progress_wait.lock); 1546b2155578SMikulas Patocka if (likely(s->in_progress > cow_threshold)) { 1547b2155578SMikulas Patocka /* 1548b2155578SMikulas Patocka * NOTE: this throttle doesn't account for whether 1549b2155578SMikulas Patocka * the caller is servicing an IO that will trigger a COW 1550b2155578SMikulas Patocka * so excess throttling may result for chunks not required 1551b2155578SMikulas Patocka * to be COW'd. But if cow_threshold was reached, extra 1552b2155578SMikulas Patocka * throttling is unlikely to negatively impact performance. 1553b2155578SMikulas Patocka */ 1554b2155578SMikulas Patocka DECLARE_WAITQUEUE(wait, current); 1555b2155578SMikulas Patocka __add_wait_queue(&s->in_progress_wait, &wait); 1556b2155578SMikulas Patocka __set_current_state(TASK_UNINTERRUPTIBLE); 1557b2155578SMikulas Patocka spin_unlock(&s->in_progress_wait.lock); 1558b2155578SMikulas Patocka if (unlock_origins) 1559b2155578SMikulas Patocka up_read(&_origins_lock); 1560b2155578SMikulas Patocka io_schedule(); 1561b2155578SMikulas Patocka remove_wait_queue(&s->in_progress_wait, &wait); 1562b2155578SMikulas Patocka return false; 1563b2155578SMikulas Patocka } 1564b2155578SMikulas Patocka spin_unlock(&s->in_progress_wait.lock); 1565b2155578SMikulas Patocka } 1566b2155578SMikulas Patocka return true; 1567a2f83e8bSMikulas Patocka } 1568a2f83e8bSMikulas Patocka 15691da177e4SLinus Torvalds /* 15701da177e4SLinus Torvalds * Flush a list of buffers. 15711da177e4SLinus Torvalds */ 15721da177e4SLinus Torvalds static void flush_bios(struct bio *bio) 15731da177e4SLinus Torvalds { 15741da177e4SLinus Torvalds struct bio *n; 15751da177e4SLinus Torvalds 15761da177e4SLinus Torvalds while (bio) { 15771da177e4SLinus Torvalds n = bio->bi_next; 15781da177e4SLinus Torvalds bio->bi_next = NULL; 1579ed00aabdSChristoph Hellwig submit_bio_noacct(bio); 15801da177e4SLinus Torvalds bio = n; 15811da177e4SLinus Torvalds } 15821da177e4SLinus Torvalds } 15831da177e4SLinus Torvalds 1584b2155578SMikulas Patocka static int do_origin(struct dm_dev *origin, struct bio *bio, bool limit); 1585515ad66cSMikulas Patocka 1586515ad66cSMikulas Patocka /* 1587515ad66cSMikulas Patocka * Flush a list of buffers. 1588515ad66cSMikulas Patocka */ 1589515ad66cSMikulas Patocka static void retry_origin_bios(struct dm_snapshot *s, struct bio *bio) 1590515ad66cSMikulas Patocka { 1591515ad66cSMikulas Patocka struct bio *n; 1592515ad66cSMikulas Patocka int r; 1593515ad66cSMikulas Patocka 1594515ad66cSMikulas Patocka while (bio) { 1595515ad66cSMikulas Patocka n = bio->bi_next; 1596515ad66cSMikulas Patocka bio->bi_next = NULL; 1597b2155578SMikulas Patocka r = do_origin(s->origin, bio, false); 1598515ad66cSMikulas Patocka if (r == DM_MAPIO_REMAPPED) 1599ed00aabdSChristoph Hellwig submit_bio_noacct(bio); 1600515ad66cSMikulas Patocka bio = n; 1601515ad66cSMikulas Patocka } 1602515ad66cSMikulas Patocka } 1603515ad66cSMikulas Patocka 16041da177e4SLinus Torvalds /* 16051da177e4SLinus Torvalds * Error a list of buffers. 16061da177e4SLinus Torvalds */ 16071da177e4SLinus Torvalds static void error_bios(struct bio *bio) 16081da177e4SLinus Torvalds { 16091da177e4SLinus Torvalds struct bio *n; 16101da177e4SLinus Torvalds 16111da177e4SLinus Torvalds while (bio) { 16121da177e4SLinus Torvalds n = bio->bi_next; 16131da177e4SLinus Torvalds bio->bi_next = NULL; 16146712ecf8SNeilBrown bio_io_error(bio); 16151da177e4SLinus Torvalds bio = n; 16161da177e4SLinus Torvalds } 16171da177e4SLinus Torvalds } 16181da177e4SLinus Torvalds 1619695368acSAlasdair G Kergon static void __invalidate_snapshot(struct dm_snapshot *s, int err) 162076df1c65SAlasdair G Kergon { 162176df1c65SAlasdair G Kergon if (!s->valid) 162276df1c65SAlasdair G Kergon return; 162376df1c65SAlasdair G Kergon 162476df1c65SAlasdair G Kergon if (err == -EIO) 162576df1c65SAlasdair G Kergon DMERR("Invalidating snapshot: Error reading/writing."); 162676df1c65SAlasdair G Kergon else if (err == -ENOMEM) 162776df1c65SAlasdair G Kergon DMERR("Invalidating snapshot: Unable to allocate exception."); 162876df1c65SAlasdair G Kergon 1629493df71cSJonathan Brassow if (s->store->type->drop_snapshot) 1630493df71cSJonathan Brassow s->store->type->drop_snapshot(s->store); 163176df1c65SAlasdair G Kergon 163276df1c65SAlasdair G Kergon s->valid = 0; 163376df1c65SAlasdair G Kergon 1634fc56f6fbSMike Snitzer dm_table_event(s->ti->table); 163576df1c65SAlasdair G Kergon } 163676df1c65SAlasdair G Kergon 16373f1637f2SNikos Tsironis static void invalidate_snapshot(struct dm_snapshot *s, int err) 16383f1637f2SNikos Tsironis { 16393f1637f2SNikos Tsironis down_write(&s->lock); 16403f1637f2SNikos Tsironis __invalidate_snapshot(s, err); 16413f1637f2SNikos Tsironis up_write(&s->lock); 16423f1637f2SNikos Tsironis } 16433f1637f2SNikos Tsironis 1644385277bfSMikulas Patocka static void pending_complete(void *context, int success) 16451da177e4SLinus Torvalds { 1646385277bfSMikulas Patocka struct dm_snap_pending_exception *pe = context; 16471d4989c8SJon Brassow struct dm_exception *e; 16481da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 16499d493fa8SAlasdair G Kergon struct bio *origin_bios = NULL; 16509d493fa8SAlasdair G Kergon struct bio *snapshot_bios = NULL; 1651a6e50b40SMikulas Patocka struct bio *full_bio = NULL; 1652f79ae415SNikos Tsironis struct dm_exception_table_lock lock; 16539d493fa8SAlasdair G Kergon int error = 0; 16541da177e4SLinus Torvalds 1655f79ae415SNikos Tsironis dm_exception_table_lock_init(s, pe->e.old_chunk, &lock); 1656f79ae415SNikos Tsironis 165776df1c65SAlasdair G Kergon if (!success) { 165876df1c65SAlasdair G Kergon /* Read/write error - snapshot is unusable */ 16593f1637f2SNikos Tsironis invalidate_snapshot(s, -EIO); 16609d493fa8SAlasdair G Kergon error = 1; 1661f79ae415SNikos Tsironis 1662f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 166376df1c65SAlasdair G Kergon goto out; 166476df1c65SAlasdair G Kergon } 166576df1c65SAlasdair G Kergon 1666119bc547SMikulas Patocka e = alloc_completed_exception(GFP_NOIO); 166776df1c65SAlasdair G Kergon if (!e) { 16683f1637f2SNikos Tsironis invalidate_snapshot(s, -ENOMEM); 16699d493fa8SAlasdair G Kergon error = 1; 1670f79ae415SNikos Tsironis 1671f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 16721da177e4SLinus Torvalds goto out; 16731da177e4SLinus Torvalds } 16741da177e4SLinus Torvalds *e = pe->e; 16751da177e4SLinus Torvalds 16763f1637f2SNikos Tsironis down_read(&s->lock); 1677f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 16789d493fa8SAlasdair G Kergon if (!s->valid) { 16793f1637f2SNikos Tsironis up_read(&s->lock); 16803510cb94SJon Brassow free_completed_exception(e); 16819d493fa8SAlasdair G Kergon error = 1; 16823f1637f2SNikos Tsironis 16839d493fa8SAlasdair G Kergon goto out; 16849d493fa8SAlasdair G Kergon } 16859d493fa8SAlasdair G Kergon 1686a8d41b59SMikulas Patocka /* 168765fc7c37SNikos Tsironis * Add a proper exception. After inserting the completed exception all 168865fc7c37SNikos Tsironis * subsequent snapshot reads to this chunk will be redirected to the 168965fc7c37SNikos Tsironis * COW device. This ensures that we do not starve. Moreover, as long 169065fc7c37SNikos Tsironis * as the pending exception exists, neither origin writes nor snapshot 169165fc7c37SNikos Tsironis * merging can overwrite the chunk in origin. 16921da177e4SLinus Torvalds */ 16933510cb94SJon Brassow dm_insert_exception(&s->complete, e); 16943f1637f2SNikos Tsironis up_read(&s->lock); 16951da177e4SLinus Torvalds 169665fc7c37SNikos Tsironis /* Wait for conflicting reads to drain */ 169765fc7c37SNikos Tsironis if (__chunk_is_tracked(s, pe->e.old_chunk)) { 1698f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 169965fc7c37SNikos Tsironis __check_for_conflicting_io(s, pe->e.old_chunk); 1700f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 170165fc7c37SNikos Tsironis } 170265fc7c37SNikos Tsironis 17031da177e4SLinus Torvalds out: 170465fc7c37SNikos Tsironis /* Remove the in-flight exception from the list */ 17053510cb94SJon Brassow dm_remove_exception(&pe->e); 1706f79ae415SNikos Tsironis 1707f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 1708f79ae415SNikos Tsironis 17099d493fa8SAlasdair G Kergon snapshot_bios = bio_list_get(&pe->snapshot_bios); 1710515ad66cSMikulas Patocka origin_bios = bio_list_get(&pe->origin_bios); 1711a6e50b40SMikulas Patocka full_bio = pe->full_bio; 1712fe3265b1SMikulas Patocka if (full_bio) 1713a6e50b40SMikulas Patocka full_bio->bi_end_io = pe->full_bio_end_io; 171473dfd078SMikulas Patocka increment_pending_exceptions_done_count(); 171573dfd078SMikulas Patocka 17169d493fa8SAlasdair G Kergon /* Submit any pending write bios */ 1717a6e50b40SMikulas Patocka if (error) { 1718a6e50b40SMikulas Patocka if (full_bio) 1719a6e50b40SMikulas Patocka bio_io_error(full_bio); 17209d493fa8SAlasdair G Kergon error_bios(snapshot_bios); 1721a6e50b40SMikulas Patocka } else { 1722a6e50b40SMikulas Patocka if (full_bio) 17234246a0b6SChristoph Hellwig bio_endio(full_bio); 17249d493fa8SAlasdair G Kergon flush_bios(snapshot_bios); 1725a6e50b40SMikulas Patocka } 17269d493fa8SAlasdair G Kergon 1727515ad66cSMikulas Patocka retry_origin_bios(s, origin_bios); 172822aa66a3SMikulas Patocka 172922aa66a3SMikulas Patocka free_pending_exception(pe); 17301da177e4SLinus Torvalds } 17311da177e4SLinus Torvalds 1732230c83afSMikulas Patocka static void complete_exception(struct dm_snap_pending_exception *pe) 1733230c83afSMikulas Patocka { 1734230c83afSMikulas Patocka struct dm_snapshot *s = pe->snap; 1735230c83afSMikulas Patocka 1736230c83afSMikulas Patocka /* Update the metadata if we are persistent */ 1737385277bfSMikulas Patocka s->store->type->commit_exception(s->store, &pe->e, !pe->copy_error, 1738385277bfSMikulas Patocka pending_complete, pe); 1739230c83afSMikulas Patocka } 1740230c83afSMikulas Patocka 17411da177e4SLinus Torvalds /* 17421da177e4SLinus Torvalds * Called when the copy I/O has finished. kcopyd actually runs 17431da177e4SLinus Torvalds * this code so don't block. 17441da177e4SLinus Torvalds */ 17454cdc1d1fSAlasdair G Kergon static void copy_callback(int read_err, unsigned long write_err, void *context) 17461da177e4SLinus Torvalds { 1747028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = context; 17481da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 17491da177e4SLinus Torvalds 1750230c83afSMikulas Patocka pe->copy_error = read_err || write_err; 17511da177e4SLinus Torvalds 1752230c83afSMikulas Patocka if (pe->exception_sequence == s->exception_complete_sequence) { 17533db2776dSDavid Jeffery struct rb_node *next; 17543db2776dSDavid Jeffery 1755230c83afSMikulas Patocka s->exception_complete_sequence++; 1756230c83afSMikulas Patocka complete_exception(pe); 1757230c83afSMikulas Patocka 17583db2776dSDavid Jeffery next = rb_first(&s->out_of_order_tree); 17593db2776dSDavid Jeffery while (next) { 17603db2776dSDavid Jeffery pe = rb_entry(next, struct dm_snap_pending_exception, 17613db2776dSDavid Jeffery out_of_order_node); 1762230c83afSMikulas Patocka if (pe->exception_sequence != s->exception_complete_sequence) 1763230c83afSMikulas Patocka break; 17643db2776dSDavid Jeffery next = rb_next(next); 1765230c83afSMikulas Patocka s->exception_complete_sequence++; 17663db2776dSDavid Jeffery rb_erase(&pe->out_of_order_node, &s->out_of_order_tree); 1767230c83afSMikulas Patocka complete_exception(pe); 17683db2776dSDavid Jeffery cond_resched(); 1769230c83afSMikulas Patocka } 1770230c83afSMikulas Patocka } else { 17713db2776dSDavid Jeffery struct rb_node *parent = NULL; 17723db2776dSDavid Jeffery struct rb_node **p = &s->out_of_order_tree.rb_node; 1773230c83afSMikulas Patocka struct dm_snap_pending_exception *pe2; 1774230c83afSMikulas Patocka 17753db2776dSDavid Jeffery while (*p) { 17763db2776dSDavid Jeffery pe2 = rb_entry(*p, struct dm_snap_pending_exception, out_of_order_node); 17773db2776dSDavid Jeffery parent = *p; 17783db2776dSDavid Jeffery 17793db2776dSDavid Jeffery BUG_ON(pe->exception_sequence == pe2->exception_sequence); 17803db2776dSDavid Jeffery if (pe->exception_sequence < pe2->exception_sequence) 17813db2776dSDavid Jeffery p = &((*p)->rb_left); 17823db2776dSDavid Jeffery else 17833db2776dSDavid Jeffery p = &((*p)->rb_right); 1784230c83afSMikulas Patocka } 17853db2776dSDavid Jeffery 17863db2776dSDavid Jeffery rb_link_node(&pe->out_of_order_node, parent, p); 17873db2776dSDavid Jeffery rb_insert_color(&pe->out_of_order_node, &s->out_of_order_tree); 1788230c83afSMikulas Patocka } 1789a2f83e8bSMikulas Patocka account_end_copy(s); 17901da177e4SLinus Torvalds } 17911da177e4SLinus Torvalds 17921da177e4SLinus Torvalds /* 17931da177e4SLinus Torvalds * Dispatches the copy operation to kcopyd. 17941da177e4SLinus Torvalds */ 1795028867acSAlasdair G Kergon static void start_copy(struct dm_snap_pending_exception *pe) 17961da177e4SLinus Torvalds { 17971da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 179822a1ceb1SHeinz Mauelshagen struct dm_io_region src, dest; 17991da177e4SLinus Torvalds struct block_device *bdev = s->origin->bdev; 18001da177e4SLinus Torvalds sector_t dev_size; 18011da177e4SLinus Torvalds 18021da177e4SLinus Torvalds dev_size = get_dev_size(bdev); 18031da177e4SLinus Torvalds 18041da177e4SLinus Torvalds src.bdev = bdev; 180571fab00aSJonathan Brassow src.sector = chunk_to_sector(s->store, pe->e.old_chunk); 1806df96eee6SMikulas Patocka src.count = min((sector_t)s->store->chunk_size, dev_size - src.sector); 18071da177e4SLinus Torvalds 1808fc56f6fbSMike Snitzer dest.bdev = s->cow->bdev; 180971fab00aSJonathan Brassow dest.sector = chunk_to_sector(s->store, pe->e.new_chunk); 18101da177e4SLinus Torvalds dest.count = src.count; 18111da177e4SLinus Torvalds 18121da177e4SLinus Torvalds /* Hand over to kcopyd */ 1813a2f83e8bSMikulas Patocka account_start_copy(s); 1814a2d2b034SJonathan Brassow dm_kcopyd_copy(s->kcopyd_client, &src, 1, &dest, 0, copy_callback, pe); 18151da177e4SLinus Torvalds } 18161da177e4SLinus Torvalds 18174246a0b6SChristoph Hellwig static void full_bio_end_io(struct bio *bio) 1818a6e50b40SMikulas Patocka { 1819a6e50b40SMikulas Patocka void *callback_data = bio->bi_private; 1820a6e50b40SMikulas Patocka 18214e4cbee9SChristoph Hellwig dm_kcopyd_do_callback(callback_data, 0, bio->bi_status ? 1 : 0); 1822a6e50b40SMikulas Patocka } 1823a6e50b40SMikulas Patocka 1824a6e50b40SMikulas Patocka static void start_full_bio(struct dm_snap_pending_exception *pe, 1825a6e50b40SMikulas Patocka struct bio *bio) 1826a6e50b40SMikulas Patocka { 1827a6e50b40SMikulas Patocka struct dm_snapshot *s = pe->snap; 1828a6e50b40SMikulas Patocka void *callback_data; 1829a6e50b40SMikulas Patocka 1830a6e50b40SMikulas Patocka pe->full_bio = bio; 1831a6e50b40SMikulas Patocka pe->full_bio_end_io = bio->bi_end_io; 1832a6e50b40SMikulas Patocka 1833a2f83e8bSMikulas Patocka account_start_copy(s); 1834a6e50b40SMikulas Patocka callback_data = dm_kcopyd_prepare_callback(s->kcopyd_client, 1835a6e50b40SMikulas Patocka copy_callback, pe); 1836a6e50b40SMikulas Patocka 1837a6e50b40SMikulas Patocka bio->bi_end_io = full_bio_end_io; 1838a6e50b40SMikulas Patocka bio->bi_private = callback_data; 1839a6e50b40SMikulas Patocka 1840ed00aabdSChristoph Hellwig submit_bio_noacct(bio); 1841a6e50b40SMikulas Patocka } 1842a6e50b40SMikulas Patocka 18432913808eSMikulas Patocka static struct dm_snap_pending_exception * 18442913808eSMikulas Patocka __lookup_pending_exception(struct dm_snapshot *s, chunk_t chunk) 18452913808eSMikulas Patocka { 18463510cb94SJon Brassow struct dm_exception *e = dm_lookup_exception(&s->pending, chunk); 18472913808eSMikulas Patocka 18482913808eSMikulas Patocka if (!e) 18492913808eSMikulas Patocka return NULL; 18502913808eSMikulas Patocka 18512913808eSMikulas Patocka return container_of(e, struct dm_snap_pending_exception, e); 18522913808eSMikulas Patocka } 18532913808eSMikulas Patocka 18541da177e4SLinus Torvalds /* 185565fc7c37SNikos Tsironis * Inserts a pending exception into the pending table. 185665fc7c37SNikos Tsironis * 18573f1637f2SNikos Tsironis * NOTE: a write lock must be held on the chunk's pending exception table slot 18583f1637f2SNikos Tsironis * before calling this. 185965fc7c37SNikos Tsironis */ 186065fc7c37SNikos Tsironis static struct dm_snap_pending_exception * 186165fc7c37SNikos Tsironis __insert_pending_exception(struct dm_snapshot *s, 186265fc7c37SNikos Tsironis struct dm_snap_pending_exception *pe, chunk_t chunk) 186365fc7c37SNikos Tsironis { 186465fc7c37SNikos Tsironis pe->e.old_chunk = chunk; 186565fc7c37SNikos Tsironis bio_list_init(&pe->origin_bios); 186665fc7c37SNikos Tsironis bio_list_init(&pe->snapshot_bios); 186765fc7c37SNikos Tsironis pe->started = 0; 186865fc7c37SNikos Tsironis pe->full_bio = NULL; 186965fc7c37SNikos Tsironis 18703f1637f2SNikos Tsironis spin_lock(&s->pe_allocation_lock); 187165fc7c37SNikos Tsironis if (s->store->type->prepare_exception(s->store, &pe->e)) { 18723f1637f2SNikos Tsironis spin_unlock(&s->pe_allocation_lock); 187365fc7c37SNikos Tsironis free_pending_exception(pe); 187465fc7c37SNikos Tsironis return NULL; 187565fc7c37SNikos Tsironis } 187665fc7c37SNikos Tsironis 187765fc7c37SNikos Tsironis pe->exception_sequence = s->exception_start_sequence++; 18783f1637f2SNikos Tsironis spin_unlock(&s->pe_allocation_lock); 187965fc7c37SNikos Tsironis 188065fc7c37SNikos Tsironis dm_insert_exception(&s->pending, &pe->e); 188165fc7c37SNikos Tsironis 188265fc7c37SNikos Tsironis return pe; 188365fc7c37SNikos Tsironis } 188465fc7c37SNikos Tsironis 188565fc7c37SNikos Tsironis /* 18861da177e4SLinus Torvalds * Looks to see if this snapshot already has a pending exception 18871da177e4SLinus Torvalds * for this chunk, otherwise it allocates a new one and inserts 18881da177e4SLinus Torvalds * it into the pending table. 18891da177e4SLinus Torvalds * 18903f1637f2SNikos Tsironis * NOTE: a write lock must be held on the chunk's pending exception table slot 18913f1637f2SNikos Tsironis * before calling this. 18921da177e4SLinus Torvalds */ 1893028867acSAlasdair G Kergon static struct dm_snap_pending_exception * 1894c6621392SMikulas Patocka __find_pending_exception(struct dm_snapshot *s, 1895c6621392SMikulas Patocka struct dm_snap_pending_exception *pe, chunk_t chunk) 18961da177e4SLinus Torvalds { 1897c6621392SMikulas Patocka struct dm_snap_pending_exception *pe2; 189876df1c65SAlasdair G Kergon 18992913808eSMikulas Patocka pe2 = __lookup_pending_exception(s, chunk); 19002913808eSMikulas Patocka if (pe2) { 19011da177e4SLinus Torvalds free_pending_exception(pe); 19022913808eSMikulas Patocka return pe2; 190376df1c65SAlasdair G Kergon } 190476df1c65SAlasdair G Kergon 190565fc7c37SNikos Tsironis return __insert_pending_exception(s, pe, chunk); 19061da177e4SLinus Torvalds } 19071da177e4SLinus Torvalds 19081d4989c8SJon Brassow static void remap_exception(struct dm_snapshot *s, struct dm_exception *e, 1909d74f81f8SMilan Broz struct bio *bio, chunk_t chunk) 19101da177e4SLinus Torvalds { 191174d46992SChristoph Hellwig bio_set_dev(bio, s->cow->bdev); 19124f024f37SKent Overstreet bio->bi_iter.bi_sector = 19134f024f37SKent Overstreet chunk_to_sector(s->store, dm_chunk_number(e->new_chunk) + 1914d74f81f8SMilan Broz (chunk - e->old_chunk)) + 19154f024f37SKent Overstreet (bio->bi_iter.bi_sector & s->store->chunk_mask); 19161da177e4SLinus Torvalds } 19171da177e4SLinus Torvalds 19182e602385SMike Snitzer static void zero_callback(int read_err, unsigned long write_err, void *context) 19192e602385SMike Snitzer { 19202e602385SMike Snitzer struct bio *bio = context; 19212e602385SMike Snitzer struct dm_snapshot *s = bio->bi_private; 19222e602385SMike Snitzer 1923a2f83e8bSMikulas Patocka account_end_copy(s); 19242e602385SMike Snitzer bio->bi_status = write_err ? BLK_STS_IOERR : 0; 19252e602385SMike Snitzer bio_endio(bio); 19262e602385SMike Snitzer } 19272e602385SMike Snitzer 19282e602385SMike Snitzer static void zero_exception(struct dm_snapshot *s, struct dm_exception *e, 19292e602385SMike Snitzer struct bio *bio, chunk_t chunk) 19302e602385SMike Snitzer { 19312e602385SMike Snitzer struct dm_io_region dest; 19322e602385SMike Snitzer 19332e602385SMike Snitzer dest.bdev = s->cow->bdev; 19342e602385SMike Snitzer dest.sector = bio->bi_iter.bi_sector; 19352e602385SMike Snitzer dest.count = s->store->chunk_size; 19362e602385SMike Snitzer 1937a2f83e8bSMikulas Patocka account_start_copy(s); 19382e602385SMike Snitzer WARN_ON_ONCE(bio->bi_private); 19392e602385SMike Snitzer bio->bi_private = s; 19402e602385SMike Snitzer dm_kcopyd_zero(s->kcopyd_client, 1, &dest, 0, zero_callback, bio); 19412e602385SMike Snitzer } 19422e602385SMike Snitzer 19432e602385SMike Snitzer static bool io_overlaps_chunk(struct dm_snapshot *s, struct bio *bio) 19442e602385SMike Snitzer { 19452e602385SMike Snitzer return bio->bi_iter.bi_size == 19462e602385SMike Snitzer (s->store->chunk_size << SECTOR_SHIFT); 19472e602385SMike Snitzer } 19482e602385SMike Snitzer 19497de3ee57SMikulas Patocka static int snapshot_map(struct dm_target *ti, struct bio *bio) 19501da177e4SLinus Torvalds { 19511d4989c8SJon Brassow struct dm_exception *e; 1952028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 1953d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED; 19541da177e4SLinus Torvalds chunk_t chunk; 1955028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = NULL; 1956f79ae415SNikos Tsironis struct dm_exception_table_lock lock; 19571da177e4SLinus Torvalds 1958ee18026aSMikulas Patocka init_tracked_chunk(bio); 1959ee18026aSMikulas Patocka 19601eff9d32SJens Axboe if (bio->bi_opf & REQ_PREFLUSH) { 196174d46992SChristoph Hellwig bio_set_dev(bio, s->cow->bdev); 1962494b3ee7SMikulas Patocka return DM_MAPIO_REMAPPED; 1963494b3ee7SMikulas Patocka } 1964494b3ee7SMikulas Patocka 19654f024f37SKent Overstreet chunk = sector_to_chunk(s->store, bio->bi_iter.bi_sector); 1966f79ae415SNikos Tsironis dm_exception_table_lock_init(s, chunk, &lock); 19671da177e4SLinus Torvalds 19681da177e4SLinus Torvalds /* Full snapshots are not usable */ 196976df1c65SAlasdair G Kergon /* To get here the table must be live so s->active is always set. */ 19701da177e4SLinus Torvalds if (!s->valid) 1971846785e6SChristoph Hellwig return DM_MAPIO_KILL; 19721da177e4SLinus Torvalds 1973b2155578SMikulas Patocka if (bio_data_dir(bio) == WRITE) { 1974b2155578SMikulas Patocka while (unlikely(!wait_for_in_progress(s, false))) 1975b2155578SMikulas Patocka ; /* wait_for_in_progress() has slept */ 1976b2155578SMikulas Patocka } 1977b2155578SMikulas Patocka 19783f1637f2SNikos Tsironis down_read(&s->lock); 1979f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 19801da177e4SLinus Torvalds 198170246286SChristoph Hellwig if (!s->valid || (unlikely(s->snapshot_overflowed) && 198270246286SChristoph Hellwig bio_data_dir(bio) == WRITE)) { 1983846785e6SChristoph Hellwig r = DM_MAPIO_KILL; 198476df1c65SAlasdair G Kergon goto out_unlock; 198576df1c65SAlasdair G Kergon } 198676df1c65SAlasdair G Kergon 19872e602385SMike Snitzer if (unlikely(bio_op(bio) == REQ_OP_DISCARD)) { 19882e602385SMike Snitzer if (s->discard_passdown_origin && dm_bio_get_target_bio_nr(bio)) { 19892e602385SMike Snitzer /* 19902e602385SMike Snitzer * passdown discard to origin (without triggering 19912e602385SMike Snitzer * snapshot exceptions via do_origin; doing so would 19922e602385SMike Snitzer * defeat the goal of freeing space in origin that is 19932e602385SMike Snitzer * implied by the "discard_passdown_origin" feature) 19942e602385SMike Snitzer */ 19952e602385SMike Snitzer bio_set_dev(bio, s->origin->bdev); 19962e602385SMike Snitzer track_chunk(s, bio, chunk); 19972e602385SMike Snitzer goto out_unlock; 19982e602385SMike Snitzer } 19992e602385SMike Snitzer /* discard to snapshot (target_bio_nr == 0) zeroes exceptions */ 20002e602385SMike Snitzer } 20012e602385SMike Snitzer 20021da177e4SLinus Torvalds /* If the block is already remapped - use that, else remap it */ 20033510cb94SJon Brassow e = dm_lookup_exception(&s->complete, chunk); 20041da177e4SLinus Torvalds if (e) { 2005d74f81f8SMilan Broz remap_exception(s, e, bio, chunk); 20062e602385SMike Snitzer if (unlikely(bio_op(bio) == REQ_OP_DISCARD) && 20072e602385SMike Snitzer io_overlaps_chunk(s, bio)) { 20082e602385SMike Snitzer dm_exception_table_unlock(&lock); 20092e602385SMike Snitzer up_read(&s->lock); 20102e602385SMike Snitzer zero_exception(s, e, bio, chunk); 20112e602385SMike Snitzer r = DM_MAPIO_SUBMITTED; /* discard is not issued */ 20122e602385SMike Snitzer goto out; 20132e602385SMike Snitzer } 20142e602385SMike Snitzer goto out_unlock; 20152e602385SMike Snitzer } 20162e602385SMike Snitzer 20172e602385SMike Snitzer if (unlikely(bio_op(bio) == REQ_OP_DISCARD)) { 20182e602385SMike Snitzer /* 20192e602385SMike Snitzer * If no exception exists, complete discard immediately 20202e602385SMike Snitzer * otherwise it'll trigger copy-out. 20212e602385SMike Snitzer */ 20222e602385SMike Snitzer bio_endio(bio); 20232e602385SMike Snitzer r = DM_MAPIO_SUBMITTED; 202476df1c65SAlasdair G Kergon goto out_unlock; 202576df1c65SAlasdair G Kergon } 20261da177e4SLinus Torvalds 2027ba40a2aaSAlasdair G Kergon /* 2028ba40a2aaSAlasdair G Kergon * Write to snapshot - higher level takes care of RW/RO 2029ba40a2aaSAlasdair G Kergon * flags so we should only get this if we are 2030962c6296SZhang Jiaming * writable. 2031ba40a2aaSAlasdair G Kergon */ 203270246286SChristoph Hellwig if (bio_data_dir(bio) == WRITE) { 20332913808eSMikulas Patocka pe = __lookup_pending_exception(s, chunk); 20342913808eSMikulas Patocka if (!pe) { 2035f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 2036c6621392SMikulas Patocka pe = alloc_pending_exception(s); 2037f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 2038c6621392SMikulas Patocka 20393510cb94SJon Brassow e = dm_lookup_exception(&s->complete, chunk); 204035bf659bSMikulas Patocka if (e) { 204135bf659bSMikulas Patocka free_pending_exception(pe); 204235bf659bSMikulas Patocka remap_exception(s, e, bio, chunk); 204335bf659bSMikulas Patocka goto out_unlock; 204435bf659bSMikulas Patocka } 204535bf659bSMikulas Patocka 2046c6621392SMikulas Patocka pe = __find_pending_exception(s, pe, chunk); 20471da177e4SLinus Torvalds if (!pe) { 2048f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 20493f1637f2SNikos Tsironis up_read(&s->lock); 20503f1637f2SNikos Tsironis 20513f1637f2SNikos Tsironis down_write(&s->lock); 2052f79ae415SNikos Tsironis 2053b0d3cc01SMike Snitzer if (s->store->userspace_supports_overflow) { 20543f1637f2SNikos Tsironis if (s->valid && !s->snapshot_overflowed) { 205576c44f6dSMikulas Patocka s->snapshot_overflowed = 1; 205676c44f6dSMikulas Patocka DMERR("Snapshot overflowed: Unable to allocate exception."); 20573f1637f2SNikos Tsironis } 2058b0d3cc01SMike Snitzer } else 2059b0d3cc01SMike Snitzer __invalidate_snapshot(s, -ENOMEM); 2060f79ae415SNikos Tsironis up_write(&s->lock); 2061f79ae415SNikos Tsironis 2062846785e6SChristoph Hellwig r = DM_MAPIO_KILL; 2063f79ae415SNikos Tsironis goto out; 206476df1c65SAlasdair G Kergon } 20652913808eSMikulas Patocka } 206676df1c65SAlasdair G Kergon 2067d74f81f8SMilan Broz remap_exception(s, &pe->e, bio, chunk); 20681da177e4SLinus Torvalds 2069d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 2070ba40a2aaSAlasdair G Kergon 20712e602385SMike Snitzer if (!pe->started && io_overlaps_chunk(s, bio)) { 2072a6e50b40SMikulas Patocka pe->started = 1; 20733f1637f2SNikos Tsironis 2074f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 20753f1637f2SNikos Tsironis up_read(&s->lock); 20763f1637f2SNikos Tsironis 2077a6e50b40SMikulas Patocka start_full_bio(pe, bio); 2078a6e50b40SMikulas Patocka goto out; 2079a6e50b40SMikulas Patocka } 2080a6e50b40SMikulas Patocka 2081a6e50b40SMikulas Patocka bio_list_add(&pe->snapshot_bios, bio); 2082a6e50b40SMikulas Patocka 20831da177e4SLinus Torvalds if (!pe->started) { 20843f1637f2SNikos Tsironis /* this is protected by the exception table lock */ 20851da177e4SLinus Torvalds pe->started = 1; 20863f1637f2SNikos Tsironis 2087f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 20883f1637f2SNikos Tsironis up_read(&s->lock); 20893f1637f2SNikos Tsironis 209076df1c65SAlasdair G Kergon start_copy(pe); 2091ba40a2aaSAlasdair G Kergon goto out; 2092ba40a2aaSAlasdair G Kergon } 2093cd45daffSMikulas Patocka } else { 209474d46992SChristoph Hellwig bio_set_dev(bio, s->origin->bdev); 2095ee18026aSMikulas Patocka track_chunk(s, bio, chunk); 2096cd45daffSMikulas Patocka } 20971da177e4SLinus Torvalds 2098ba40a2aaSAlasdair G Kergon out_unlock: 2099f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 21003f1637f2SNikos Tsironis up_read(&s->lock); 2101ba40a2aaSAlasdair G Kergon out: 21021da177e4SLinus Torvalds return r; 21031da177e4SLinus Torvalds } 21041da177e4SLinus Torvalds 21053452c2a1SMikulas Patocka /* 21063452c2a1SMikulas Patocka * A snapshot-merge target behaves like a combination of a snapshot 21073452c2a1SMikulas Patocka * target and a snapshot-origin target. It only generates new 21083452c2a1SMikulas Patocka * exceptions in other snapshots and not in the one that is being 21093452c2a1SMikulas Patocka * merged. 21103452c2a1SMikulas Patocka * 21113452c2a1SMikulas Patocka * For each chunk, if there is an existing exception, it is used to 21123452c2a1SMikulas Patocka * redirect I/O to the cow device. Otherwise I/O is sent to the origin, 21133452c2a1SMikulas Patocka * which in turn might generate exceptions in other snapshots. 21149fe86254SMikulas Patocka * If merging is currently taking place on the chunk in question, the 21159fe86254SMikulas Patocka * I/O is deferred by adding it to s->bios_queued_during_merge. 21163452c2a1SMikulas Patocka */ 21177de3ee57SMikulas Patocka static int snapshot_merge_map(struct dm_target *ti, struct bio *bio) 21183452c2a1SMikulas Patocka { 21193452c2a1SMikulas Patocka struct dm_exception *e; 21203452c2a1SMikulas Patocka struct dm_snapshot *s = ti->private; 21213452c2a1SMikulas Patocka int r = DM_MAPIO_REMAPPED; 21223452c2a1SMikulas Patocka chunk_t chunk; 21233452c2a1SMikulas Patocka 2124ee18026aSMikulas Patocka init_tracked_chunk(bio); 2125ee18026aSMikulas Patocka 21261eff9d32SJens Axboe if (bio->bi_opf & REQ_PREFLUSH) { 212755a62eefSAlasdair G Kergon if (!dm_bio_get_target_bio_nr(bio)) 212874d46992SChristoph Hellwig bio_set_dev(bio, s->origin->bdev); 212910b8106aSMike Snitzer else 213074d46992SChristoph Hellwig bio_set_dev(bio, s->cow->bdev); 213110b8106aSMike Snitzer return DM_MAPIO_REMAPPED; 213210b8106aSMike Snitzer } 213310b8106aSMike Snitzer 21343ee25485SMike Snitzer if (unlikely(bio_op(bio) == REQ_OP_DISCARD)) { 21353ee25485SMike Snitzer /* Once merging, discards no longer effect change */ 21363ee25485SMike Snitzer bio_endio(bio); 21373ee25485SMike Snitzer return DM_MAPIO_SUBMITTED; 21383ee25485SMike Snitzer } 21393ee25485SMike Snitzer 21404f024f37SKent Overstreet chunk = sector_to_chunk(s->store, bio->bi_iter.bi_sector); 21413452c2a1SMikulas Patocka 21424ad8d880SNikos Tsironis down_write(&s->lock); 21433452c2a1SMikulas Patocka 2144d2fdb776SMikulas Patocka /* Full merging snapshots are redirected to the origin */ 2145d2fdb776SMikulas Patocka if (!s->valid) 2146d2fdb776SMikulas Patocka goto redirect_to_origin; 21473452c2a1SMikulas Patocka 21483452c2a1SMikulas Patocka /* If the block is already remapped - use that */ 21493452c2a1SMikulas Patocka e = dm_lookup_exception(&s->complete, chunk); 21503452c2a1SMikulas Patocka if (e) { 21519fe86254SMikulas Patocka /* Queue writes overlapping with chunks being merged */ 215270246286SChristoph Hellwig if (bio_data_dir(bio) == WRITE && 21539fe86254SMikulas Patocka chunk >= s->first_merging_chunk && 21549fe86254SMikulas Patocka chunk < (s->first_merging_chunk + 21559fe86254SMikulas Patocka s->num_merging_chunks)) { 215674d46992SChristoph Hellwig bio_set_dev(bio, s->origin->bdev); 21579fe86254SMikulas Patocka bio_list_add(&s->bios_queued_during_merge, bio); 21589fe86254SMikulas Patocka r = DM_MAPIO_SUBMITTED; 21599fe86254SMikulas Patocka goto out_unlock; 21609fe86254SMikulas Patocka } 216117aa0332SMikulas Patocka 21623452c2a1SMikulas Patocka remap_exception(s, e, bio, chunk); 216317aa0332SMikulas Patocka 216470246286SChristoph Hellwig if (bio_data_dir(bio) == WRITE) 2165ee18026aSMikulas Patocka track_chunk(s, bio, chunk); 21663452c2a1SMikulas Patocka goto out_unlock; 21673452c2a1SMikulas Patocka } 21683452c2a1SMikulas Patocka 2169d2fdb776SMikulas Patocka redirect_to_origin: 217074d46992SChristoph Hellwig bio_set_dev(bio, s->origin->bdev); 21713452c2a1SMikulas Patocka 217270246286SChristoph Hellwig if (bio_data_dir(bio) == WRITE) { 21734ad8d880SNikos Tsironis up_write(&s->lock); 2174b2155578SMikulas Patocka return do_origin(s->origin, bio, false); 21753452c2a1SMikulas Patocka } 21763452c2a1SMikulas Patocka 21773452c2a1SMikulas Patocka out_unlock: 21784ad8d880SNikos Tsironis up_write(&s->lock); 21793452c2a1SMikulas Patocka 21803452c2a1SMikulas Patocka return r; 21813452c2a1SMikulas Patocka } 21823452c2a1SMikulas Patocka 21834e4cbee9SChristoph Hellwig static int snapshot_end_io(struct dm_target *ti, struct bio *bio, 21844e4cbee9SChristoph Hellwig blk_status_t *error) 2185cd45daffSMikulas Patocka { 2186cd45daffSMikulas Patocka struct dm_snapshot *s = ti->private; 2187cd45daffSMikulas Patocka 2188ee18026aSMikulas Patocka if (is_bio_tracked(bio)) 2189ee18026aSMikulas Patocka stop_tracking_chunk(s, bio); 2190cd45daffSMikulas Patocka 21911be56909SChristoph Hellwig return DM_ENDIO_DONE; 2192cd45daffSMikulas Patocka } 2193cd45daffSMikulas Patocka 21941e03f97eSMikulas Patocka static void snapshot_merge_presuspend(struct dm_target *ti) 21951e03f97eSMikulas Patocka { 21961e03f97eSMikulas Patocka struct dm_snapshot *s = ti->private; 21971e03f97eSMikulas Patocka 21981e03f97eSMikulas Patocka stop_merge(s); 21991e03f97eSMikulas Patocka } 22001e03f97eSMikulas Patocka 2201c1f0c183SMike Snitzer static int snapshot_preresume(struct dm_target *ti) 2202c1f0c183SMike Snitzer { 2203c1f0c183SMike Snitzer int r = 0; 2204c1f0c183SMike Snitzer struct dm_snapshot *s = ti->private; 2205c1f0c183SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 2206c1f0c183SMike Snitzer 2207c1f0c183SMike Snitzer down_read(&_origins_lock); 22089d3b15c4SMikulas Patocka (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); 2209c1f0c183SMike Snitzer if (snap_src && snap_dest) { 22104ad8d880SNikos Tsironis down_read(&snap_src->lock); 2211c1f0c183SMike Snitzer if (s == snap_src) { 2212c1f0c183SMike Snitzer DMERR("Unable to resume snapshot source until " 2213c1f0c183SMike Snitzer "handover completes."); 2214c1f0c183SMike Snitzer r = -EINVAL; 2215b83b2f29SMike Snitzer } else if (!dm_suspended(snap_src->ti)) { 2216c1f0c183SMike Snitzer DMERR("Unable to perform snapshot handover until " 2217c1f0c183SMike Snitzer "source is suspended."); 2218c1f0c183SMike Snitzer r = -EINVAL; 2219c1f0c183SMike Snitzer } 22204ad8d880SNikos Tsironis up_read(&snap_src->lock); 2221c1f0c183SMike Snitzer } 2222c1f0c183SMike Snitzer up_read(&_origins_lock); 2223c1f0c183SMike Snitzer 2224c1f0c183SMike Snitzer return r; 2225c1f0c183SMike Snitzer } 2226c1f0c183SMike Snitzer 22271da177e4SLinus Torvalds static void snapshot_resume(struct dm_target *ti) 22281da177e4SLinus Torvalds { 2229028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 223009ee96b2SMikulas Patocka struct dm_snapshot *snap_src = NULL, *snap_dest = NULL, *snap_merging = NULL; 2231b735fedeSMikulas Patocka struct dm_origin *o; 2232b735fedeSMikulas Patocka struct mapped_device *origin_md = NULL; 223309ee96b2SMikulas Patocka bool must_restart_merging = false; 2234c1f0c183SMike Snitzer 2235c1f0c183SMike Snitzer down_read(&_origins_lock); 2236b735fedeSMikulas Patocka 2237b735fedeSMikulas Patocka o = __lookup_dm_origin(s->origin->bdev); 2238b735fedeSMikulas Patocka if (o) 2239b735fedeSMikulas Patocka origin_md = dm_table_get_md(o->ti->table); 224009ee96b2SMikulas Patocka if (!origin_md) { 224109ee96b2SMikulas Patocka (void) __find_snapshots_sharing_cow(s, NULL, NULL, &snap_merging); 224209ee96b2SMikulas Patocka if (snap_merging) 224309ee96b2SMikulas Patocka origin_md = dm_table_get_md(snap_merging->ti->table); 224409ee96b2SMikulas Patocka } 2245b735fedeSMikulas Patocka if (origin_md == dm_table_get_md(ti->table)) 2246b735fedeSMikulas Patocka origin_md = NULL; 224709ee96b2SMikulas Patocka if (origin_md) { 224809ee96b2SMikulas Patocka if (dm_hold(origin_md)) 224909ee96b2SMikulas Patocka origin_md = NULL; 225009ee96b2SMikulas Patocka } 2251b735fedeSMikulas Patocka 225209ee96b2SMikulas Patocka up_read(&_origins_lock); 225309ee96b2SMikulas Patocka 225409ee96b2SMikulas Patocka if (origin_md) { 2255b735fedeSMikulas Patocka dm_internal_suspend_fast(origin_md); 225609ee96b2SMikulas Patocka if (snap_merging && test_bit(RUNNING_MERGE, &snap_merging->state_bits)) { 225709ee96b2SMikulas Patocka must_restart_merging = true; 225809ee96b2SMikulas Patocka stop_merge(snap_merging); 225909ee96b2SMikulas Patocka } 226009ee96b2SMikulas Patocka } 226109ee96b2SMikulas Patocka 226209ee96b2SMikulas Patocka down_read(&_origins_lock); 2263b735fedeSMikulas Patocka 22649d3b15c4SMikulas Patocka (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); 2265c1f0c183SMike Snitzer if (snap_src && snap_dest) { 22664ad8d880SNikos Tsironis down_write(&snap_src->lock); 22674ad8d880SNikos Tsironis down_write_nested(&snap_dest->lock, SINGLE_DEPTH_NESTING); 2268c1f0c183SMike Snitzer __handover_exceptions(snap_src, snap_dest); 22694ad8d880SNikos Tsironis up_write(&snap_dest->lock); 22704ad8d880SNikos Tsironis up_write(&snap_src->lock); 2271c1f0c183SMike Snitzer } 2272b735fedeSMikulas Patocka 2273c1f0c183SMike Snitzer up_read(&_origins_lock); 2274c1f0c183SMike Snitzer 227509ee96b2SMikulas Patocka if (origin_md) { 227609ee96b2SMikulas Patocka if (must_restart_merging) 227709ee96b2SMikulas Patocka start_merge(snap_merging); 227809ee96b2SMikulas Patocka dm_internal_resume_fast(origin_md); 227909ee96b2SMikulas Patocka dm_put(origin_md); 228009ee96b2SMikulas Patocka } 228109ee96b2SMikulas Patocka 2282c1f0c183SMike Snitzer /* Now we have correct chunk size, reregister */ 2283c1f0c183SMike Snitzer reregister_snapshot(s); 22841da177e4SLinus Torvalds 22854ad8d880SNikos Tsironis down_write(&s->lock); 2286aa14edebSAlasdair G Kergon s->active = 1; 22874ad8d880SNikos Tsironis up_write(&s->lock); 22881da177e4SLinus Torvalds } 22891da177e4SLinus Torvalds 2290542f9038SMike Snitzer static uint32_t get_origin_minimum_chunksize(struct block_device *bdev) 22911e03f97eSMikulas Patocka { 2292542f9038SMike Snitzer uint32_t min_chunksize; 22931e03f97eSMikulas Patocka 22941e03f97eSMikulas Patocka down_read(&_origins_lock); 22951e03f97eSMikulas Patocka min_chunksize = __minimum_chunk_size(__lookup_origin(bdev)); 22961e03f97eSMikulas Patocka up_read(&_origins_lock); 22971e03f97eSMikulas Patocka 22981e03f97eSMikulas Patocka return min_chunksize; 22991e03f97eSMikulas Patocka } 23001e03f97eSMikulas Patocka 23011e03f97eSMikulas Patocka static void snapshot_merge_resume(struct dm_target *ti) 23021e03f97eSMikulas Patocka { 23031e03f97eSMikulas Patocka struct dm_snapshot *s = ti->private; 23041e03f97eSMikulas Patocka 23051e03f97eSMikulas Patocka /* 23061e03f97eSMikulas Patocka * Handover exceptions from existing snapshot. 23071e03f97eSMikulas Patocka */ 23081e03f97eSMikulas Patocka snapshot_resume(ti); 23091e03f97eSMikulas Patocka 23101e03f97eSMikulas Patocka /* 2311542f9038SMike Snitzer * snapshot-merge acts as an origin, so set ti->max_io_len 23121e03f97eSMikulas Patocka */ 2313542f9038SMike Snitzer ti->max_io_len = get_origin_minimum_chunksize(s->origin->bdev); 23141e03f97eSMikulas Patocka 23151e03f97eSMikulas Patocka start_merge(s); 23161e03f97eSMikulas Patocka } 23171e03f97eSMikulas Patocka 2318fd7c092eSMikulas Patocka static void snapshot_status(struct dm_target *ti, status_type_t type, 231986a3238cSHeinz Mauelshagen unsigned int status_flags, char *result, unsigned int maxlen) 23201da177e4SLinus Torvalds { 232186a3238cSHeinz Mauelshagen unsigned int sz = 0; 2322028867acSAlasdair G Kergon struct dm_snapshot *snap = ti->private; 232386a3238cSHeinz Mauelshagen unsigned int num_features; 23241da177e4SLinus Torvalds 23251da177e4SLinus Torvalds switch (type) { 23261da177e4SLinus Torvalds case STATUSTYPE_INFO: 232794e76572SMikulas Patocka 23284ad8d880SNikos Tsironis down_write(&snap->lock); 232994e76572SMikulas Patocka 23301da177e4SLinus Torvalds if (!snap->valid) 23312e4a31dfSJonathan Brassow DMEMIT("Invalid"); 2332d8ddb1cfSMike Snitzer else if (snap->merge_failed) 2333d8ddb1cfSMike Snitzer DMEMIT("Merge failed"); 233476c44f6dSMikulas Patocka else if (snap->snapshot_overflowed) 233576c44f6dSMikulas Patocka DMEMIT("Overflow"); 23361da177e4SLinus Torvalds else { 2337985903bbSMike Snitzer if (snap->store->type->usage) { 2338985903bbSMike Snitzer sector_t total_sectors, sectors_allocated, 2339985903bbSMike Snitzer metadata_sectors; 2340985903bbSMike Snitzer snap->store->type->usage(snap->store, 2341985903bbSMike Snitzer &total_sectors, 2342985903bbSMike Snitzer §ors_allocated, 2343985903bbSMike Snitzer &metadata_sectors); 2344985903bbSMike Snitzer DMEMIT("%llu/%llu %llu", 2345985903bbSMike Snitzer (unsigned long long)sectors_allocated, 2346985903bbSMike Snitzer (unsigned long long)total_sectors, 2347985903bbSMike Snitzer (unsigned long long)metadata_sectors); 2348*03b18887SHeinz Mauelshagen } else 23492e4a31dfSJonathan Brassow DMEMIT("Unknown"); 23501da177e4SLinus Torvalds } 235194e76572SMikulas Patocka 23524ad8d880SNikos Tsironis up_write(&snap->lock); 235394e76572SMikulas Patocka 23541da177e4SLinus Torvalds break; 23551da177e4SLinus Torvalds 23561da177e4SLinus Torvalds case STATUSTYPE_TABLE: 23571da177e4SLinus Torvalds /* 23581da177e4SLinus Torvalds * kdevname returns a static pointer so we need 23591da177e4SLinus Torvalds * to make private copies if the output is to 23601da177e4SLinus Torvalds * make sense. 23611da177e4SLinus Torvalds */ 2362fc56f6fbSMike Snitzer DMEMIT("%s %s", snap->origin->name, snap->cow->name); 23632e602385SMike Snitzer sz += snap->store->type->status(snap->store, type, result + sz, 23641e302a92SJonathan Brassow maxlen - sz); 23652e602385SMike Snitzer num_features = snap->discard_zeroes_cow + snap->discard_passdown_origin; 23662e602385SMike Snitzer if (num_features) { 23672e602385SMike Snitzer DMEMIT(" %u", num_features); 23682e602385SMike Snitzer if (snap->discard_zeroes_cow) 23692e602385SMike Snitzer DMEMIT(" discard_zeroes_cow"); 23702e602385SMike Snitzer if (snap->discard_passdown_origin) 23712e602385SMike Snitzer DMEMIT(" discard_passdown_origin"); 23722e602385SMike Snitzer } 23731da177e4SLinus Torvalds break; 23748ec45662STushar Sugandhi 23758ec45662STushar Sugandhi case STATUSTYPE_IMA: 23768ec45662STushar Sugandhi DMEMIT_TARGET_NAME_VERSION(ti->type); 23778ec45662STushar Sugandhi DMEMIT(",snap_origin_name=%s", snap->origin->name); 23788ec45662STushar Sugandhi DMEMIT(",snap_cow_name=%s", snap->cow->name); 23798ec45662STushar Sugandhi DMEMIT(",snap_valid=%c", snap->valid ? 'y' : 'n'); 23808ec45662STushar Sugandhi DMEMIT(",snap_merge_failed=%c", snap->merge_failed ? 'y' : 'n'); 23818ec45662STushar Sugandhi DMEMIT(",snapshot_overflowed=%c", snap->snapshot_overflowed ? 'y' : 'n'); 23828ec45662STushar Sugandhi DMEMIT(";"); 23838ec45662STushar Sugandhi break; 23841da177e4SLinus Torvalds } 23851da177e4SLinus Torvalds } 23861da177e4SLinus Torvalds 23878811f46cSMike Snitzer static int snapshot_iterate_devices(struct dm_target *ti, 23888811f46cSMike Snitzer iterate_devices_callout_fn fn, void *data) 23898811f46cSMike Snitzer { 23908811f46cSMike Snitzer struct dm_snapshot *snap = ti->private; 23911e5554c8SMikulas Patocka int r; 23928811f46cSMike Snitzer 23931e5554c8SMikulas Patocka r = fn(ti, snap->origin, 0, ti->len, data); 23941e5554c8SMikulas Patocka 23951e5554c8SMikulas Patocka if (!r) 23961e5554c8SMikulas Patocka r = fn(ti, snap->cow, 0, get_dev_size(snap->cow->bdev), data); 23971e5554c8SMikulas Patocka 23981e5554c8SMikulas Patocka return r; 23998811f46cSMike Snitzer } 24008811f46cSMike Snitzer 24012e602385SMike Snitzer static void snapshot_io_hints(struct dm_target *ti, struct queue_limits *limits) 24022e602385SMike Snitzer { 24032e602385SMike Snitzer struct dm_snapshot *snap = ti->private; 24042e602385SMike Snitzer 24052e602385SMike Snitzer if (snap->discard_zeroes_cow) { 24062e602385SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 24072e602385SMike Snitzer 24083ee25485SMike Snitzer down_read(&_origins_lock); 24093ee25485SMike Snitzer 24102e602385SMike Snitzer (void) __find_snapshots_sharing_cow(snap, &snap_src, &snap_dest, NULL); 24112e602385SMike Snitzer if (snap_src && snap_dest) 24122e602385SMike Snitzer snap = snap_src; 24132e602385SMike Snitzer 24142e602385SMike Snitzer /* All discards are split on chunk_size boundary */ 24152e602385SMike Snitzer limits->discard_granularity = snap->store->chunk_size; 24162e602385SMike Snitzer limits->max_discard_sectors = snap->store->chunk_size; 24173ee25485SMike Snitzer 24183ee25485SMike Snitzer up_read(&_origins_lock); 24192e602385SMike Snitzer } 24202e602385SMike Snitzer } 24218811f46cSMike Snitzer 2422a4a82ce3SHeinz Mauelshagen /* 2423a4a82ce3SHeinz Mauelshagen *--------------------------------------------------------------- 24241da177e4SLinus Torvalds * Origin methods 2425a4a82ce3SHeinz Mauelshagen *--------------------------------------------------------------- 2426a4a82ce3SHeinz Mauelshagen */ 24279eaae8ffSMikulas Patocka /* 24289eaae8ffSMikulas Patocka * If no exceptions need creating, DM_MAPIO_REMAPPED is returned and any 24299eaae8ffSMikulas Patocka * supplied bio was ignored. The caller may submit it immediately. 24309eaae8ffSMikulas Patocka * (No remapping actually occurs as the origin is always a direct linear 24319eaae8ffSMikulas Patocka * map.) 24329eaae8ffSMikulas Patocka * 24339eaae8ffSMikulas Patocka * If further exceptions are required, DM_MAPIO_SUBMITTED is returned 24349eaae8ffSMikulas Patocka * and any supplied bio is added to a list to be submitted once all 24359eaae8ffSMikulas Patocka * the necessary exceptions exist. 24369eaae8ffSMikulas Patocka */ 24379eaae8ffSMikulas Patocka static int __origin_write(struct list_head *snapshots, sector_t sector, 24389eaae8ffSMikulas Patocka struct bio *bio) 24391da177e4SLinus Torvalds { 2440515ad66cSMikulas Patocka int r = DM_MAPIO_REMAPPED; 24411da177e4SLinus Torvalds struct dm_snapshot *snap; 24421d4989c8SJon Brassow struct dm_exception *e; 244365fc7c37SNikos Tsironis struct dm_snap_pending_exception *pe, *pe2; 2444515ad66cSMikulas Patocka struct dm_snap_pending_exception *pe_to_start_now = NULL; 2445515ad66cSMikulas Patocka struct dm_snap_pending_exception *pe_to_start_last = NULL; 2446f79ae415SNikos Tsironis struct dm_exception_table_lock lock; 24471da177e4SLinus Torvalds chunk_t chunk; 24481da177e4SLinus Torvalds 24491da177e4SLinus Torvalds /* Do all the snapshots on this origin */ 24501da177e4SLinus Torvalds list_for_each_entry(snap, snapshots, list) { 24513452c2a1SMikulas Patocka /* 24523452c2a1SMikulas Patocka * Don't make new exceptions in a merging snapshot 24533452c2a1SMikulas Patocka * because it has effectively been deleted 24543452c2a1SMikulas Patocka */ 24553452c2a1SMikulas Patocka if (dm_target_is_snapshot_merge(snap->ti)) 24563452c2a1SMikulas Patocka continue; 24573452c2a1SMikulas Patocka 2458d5e404c1SAlasdair G Kergon /* Nothing to do if writing beyond end of snapshot */ 24599eaae8ffSMikulas Patocka if (sector >= dm_table_get_size(snap->ti->table)) 2460f79ae415SNikos Tsironis continue; 24611da177e4SLinus Torvalds 24621da177e4SLinus Torvalds /* 24631da177e4SLinus Torvalds * Remember, different snapshots can have 24641da177e4SLinus Torvalds * different chunk sizes. 24651da177e4SLinus Torvalds */ 24669eaae8ffSMikulas Patocka chunk = sector_to_chunk(snap->store, sector); 2467f79ae415SNikos Tsironis dm_exception_table_lock_init(snap, chunk, &lock); 2468f79ae415SNikos Tsironis 24693f1637f2SNikos Tsironis down_read(&snap->lock); 2470f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 2471f79ae415SNikos Tsironis 2472f79ae415SNikos Tsironis /* Only deal with valid and active snapshots */ 2473f79ae415SNikos Tsironis if (!snap->valid || !snap->active) 2474f79ae415SNikos Tsironis goto next_snapshot; 24751da177e4SLinus Torvalds 247665fc7c37SNikos Tsironis pe = __lookup_pending_exception(snap, chunk); 247765fc7c37SNikos Tsironis if (!pe) { 24781da177e4SLinus Torvalds /* 247965fc7c37SNikos Tsironis * Check exception table to see if block is already 248065fc7c37SNikos Tsironis * remapped in this snapshot and trigger an exception 248165fc7c37SNikos Tsironis * if not. 24821da177e4SLinus Torvalds */ 24833510cb94SJon Brassow e = dm_lookup_exception(&snap->complete, chunk); 248476df1c65SAlasdair G Kergon if (e) 248576df1c65SAlasdair G Kergon goto next_snapshot; 248676df1c65SAlasdair G Kergon 2487f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 2488c6621392SMikulas Patocka pe = alloc_pending_exception(snap); 2489f79ae415SNikos Tsironis dm_exception_table_lock(&lock); 2490c6621392SMikulas Patocka 249165fc7c37SNikos Tsironis pe2 = __lookup_pending_exception(snap, chunk); 249265fc7c37SNikos Tsironis 249365fc7c37SNikos Tsironis if (!pe2) { 24943510cb94SJon Brassow e = dm_lookup_exception(&snap->complete, chunk); 249535bf659bSMikulas Patocka if (e) { 249635bf659bSMikulas Patocka free_pending_exception(pe); 249735bf659bSMikulas Patocka goto next_snapshot; 249835bf659bSMikulas Patocka } 249935bf659bSMikulas Patocka 250065fc7c37SNikos Tsironis pe = __insert_pending_exception(snap, pe, chunk); 25011da177e4SLinus Torvalds if (!pe) { 2502f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 25033f1637f2SNikos Tsironis up_read(&snap->lock); 2504f79ae415SNikos Tsironis 25053f1637f2SNikos Tsironis invalidate_snapshot(snap, -ENOMEM); 2506f79ae415SNikos Tsironis continue; 250776df1c65SAlasdair G Kergon } 250865fc7c37SNikos Tsironis } else { 250965fc7c37SNikos Tsironis free_pending_exception(pe); 251065fc7c37SNikos Tsironis pe = pe2; 251165fc7c37SNikos Tsironis } 25122913808eSMikulas Patocka } 25131da177e4SLinus Torvalds 2514d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 251576df1c65SAlasdair G Kergon 2516515ad66cSMikulas Patocka /* 2517515ad66cSMikulas Patocka * If an origin bio was supplied, queue it to wait for the 2518515ad66cSMikulas Patocka * completion of this exception, and start this one last, 2519515ad66cSMikulas Patocka * at the end of the function. 2520515ad66cSMikulas Patocka */ 2521515ad66cSMikulas Patocka if (bio) { 2522515ad66cSMikulas Patocka bio_list_add(&pe->origin_bios, bio); 2523515ad66cSMikulas Patocka bio = NULL; 2524515ad66cSMikulas Patocka 2525515ad66cSMikulas Patocka if (!pe->started) { 2526515ad66cSMikulas Patocka pe->started = 1; 2527515ad66cSMikulas Patocka pe_to_start_last = pe; 2528515ad66cSMikulas Patocka } 2529b4b610f6SAlasdair G Kergon } 253076df1c65SAlasdair G Kergon 2531eccf0817SAlasdair G Kergon if (!pe->started) { 2532eccf0817SAlasdair G Kergon pe->started = 1; 2533515ad66cSMikulas Patocka pe_to_start_now = pe; 2534eccf0817SAlasdair G Kergon } 25351da177e4SLinus Torvalds 253676df1c65SAlasdair G Kergon next_snapshot: 2537f79ae415SNikos Tsironis dm_exception_table_unlock(&lock); 25383f1637f2SNikos Tsironis up_read(&snap->lock); 2539515ad66cSMikulas Patocka 2540515ad66cSMikulas Patocka if (pe_to_start_now) { 2541515ad66cSMikulas Patocka start_copy(pe_to_start_now); 2542515ad66cSMikulas Patocka pe_to_start_now = NULL; 25431da177e4SLinus Torvalds } 2544b4b610f6SAlasdair G Kergon } 2545b4b610f6SAlasdair G Kergon 25461da177e4SLinus Torvalds /* 2547515ad66cSMikulas Patocka * Submit the exception against which the bio is queued last, 2548515ad66cSMikulas Patocka * to give the other exceptions a head start. 25491da177e4SLinus Torvalds */ 2550515ad66cSMikulas Patocka if (pe_to_start_last) 2551515ad66cSMikulas Patocka start_copy(pe_to_start_last); 25521da177e4SLinus Torvalds 25531da177e4SLinus Torvalds return r; 25541da177e4SLinus Torvalds } 25551da177e4SLinus Torvalds 25561da177e4SLinus Torvalds /* 25571da177e4SLinus Torvalds * Called on a write from the origin driver. 25581da177e4SLinus Torvalds */ 2559b2155578SMikulas Patocka static int do_origin(struct dm_dev *origin, struct bio *bio, bool limit) 25601da177e4SLinus Torvalds { 25611da177e4SLinus Torvalds struct origin *o; 2562d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED; 25631da177e4SLinus Torvalds 2564b2155578SMikulas Patocka again: 25651da177e4SLinus Torvalds down_read(&_origins_lock); 25661da177e4SLinus Torvalds o = __lookup_origin(origin->bdev); 2567b2155578SMikulas Patocka if (o) { 2568b2155578SMikulas Patocka if (limit) { 2569b2155578SMikulas Patocka struct dm_snapshot *s; 2570b2155578SMikulas Patocka list_for_each_entry(s, &o->snapshots, list) 2571b2155578SMikulas Patocka if (unlikely(!wait_for_in_progress(s, true))) 2572b2155578SMikulas Patocka goto again; 2573b2155578SMikulas Patocka } 2574b2155578SMikulas Patocka 25754f024f37SKent Overstreet r = __origin_write(&o->snapshots, bio->bi_iter.bi_sector, bio); 2576b2155578SMikulas Patocka } 25771da177e4SLinus Torvalds up_read(&_origins_lock); 25781da177e4SLinus Torvalds 25791da177e4SLinus Torvalds return r; 25801da177e4SLinus Torvalds } 25811da177e4SLinus Torvalds 25821da177e4SLinus Torvalds /* 258373dfd078SMikulas Patocka * Trigger exceptions in all non-merging snapshots. 258473dfd078SMikulas Patocka * 258573dfd078SMikulas Patocka * The chunk size of the merging snapshot may be larger than the chunk 258673dfd078SMikulas Patocka * size of some other snapshot so we may need to reallocate multiple 258773dfd078SMikulas Patocka * chunks in other snapshots. 258873dfd078SMikulas Patocka * 258973dfd078SMikulas Patocka * We scan all the overlapping exceptions in the other snapshots. 259073dfd078SMikulas Patocka * Returns 1 if anything was reallocated and must be waited for, 259173dfd078SMikulas Patocka * otherwise returns 0. 259273dfd078SMikulas Patocka * 259373dfd078SMikulas Patocka * size must be a multiple of merging_snap's chunk_size. 259473dfd078SMikulas Patocka */ 259573dfd078SMikulas Patocka static int origin_write_extent(struct dm_snapshot *merging_snap, 259686a3238cSHeinz Mauelshagen sector_t sector, unsigned int size) 259773dfd078SMikulas Patocka { 259873dfd078SMikulas Patocka int must_wait = 0; 259973dfd078SMikulas Patocka sector_t n; 260073dfd078SMikulas Patocka struct origin *o; 260173dfd078SMikulas Patocka 260273dfd078SMikulas Patocka /* 2603542f9038SMike Snitzer * The origin's __minimum_chunk_size() got stored in max_io_len 260473dfd078SMikulas Patocka * by snapshot_merge_resume(). 260573dfd078SMikulas Patocka */ 260673dfd078SMikulas Patocka down_read(&_origins_lock); 260773dfd078SMikulas Patocka o = __lookup_origin(merging_snap->origin->bdev); 2608542f9038SMike Snitzer for (n = 0; n < size; n += merging_snap->ti->max_io_len) 260973dfd078SMikulas Patocka if (__origin_write(&o->snapshots, sector + n, NULL) == 261073dfd078SMikulas Patocka DM_MAPIO_SUBMITTED) 261173dfd078SMikulas Patocka must_wait = 1; 261273dfd078SMikulas Patocka up_read(&_origins_lock); 261373dfd078SMikulas Patocka 261473dfd078SMikulas Patocka return must_wait; 261573dfd078SMikulas Patocka } 261673dfd078SMikulas Patocka 261773dfd078SMikulas Patocka /* 26181da177e4SLinus Torvalds * Origin: maps a linear range of a device, with hooks for snapshotting. 26191da177e4SLinus Torvalds */ 26201da177e4SLinus Torvalds 26211da177e4SLinus Torvalds /* 26221da177e4SLinus Torvalds * Construct an origin mapping: <dev_path> 26231da177e4SLinus Torvalds * The context for an origin is merely a 'struct dm_dev *' 26241da177e4SLinus Torvalds * pointing to the real device. 26251da177e4SLinus Torvalds */ 26261da177e4SLinus Torvalds static int origin_ctr(struct dm_target *ti, unsigned int argc, char **argv) 26271da177e4SLinus Torvalds { 26281da177e4SLinus Torvalds int r; 2629599cdf3bSMikulas Patocka struct dm_origin *o; 26301da177e4SLinus Torvalds 26311da177e4SLinus Torvalds if (argc != 1) { 263272d94861SAlasdair G Kergon ti->error = "origin: incorrect number of arguments"; 26331da177e4SLinus Torvalds return -EINVAL; 26341da177e4SLinus Torvalds } 26351da177e4SLinus Torvalds 2636599cdf3bSMikulas Patocka o = kmalloc(sizeof(struct dm_origin), GFP_KERNEL); 2637599cdf3bSMikulas Patocka if (!o) { 2638599cdf3bSMikulas Patocka ti->error = "Cannot allocate private origin structure"; 2639599cdf3bSMikulas Patocka r = -ENOMEM; 2640599cdf3bSMikulas Patocka goto bad_alloc; 26411da177e4SLinus Torvalds } 26421da177e4SLinus Torvalds 2643599cdf3bSMikulas Patocka r = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &o->dev); 2644599cdf3bSMikulas Patocka if (r) { 2645599cdf3bSMikulas Patocka ti->error = "Cannot get target device"; 2646599cdf3bSMikulas Patocka goto bad_open; 2647599cdf3bSMikulas Patocka } 2648599cdf3bSMikulas Patocka 2649b735fedeSMikulas Patocka o->ti = ti; 2650599cdf3bSMikulas Patocka ti->private = o; 265155a62eefSAlasdair G Kergon ti->num_flush_bios = 1; 2652494b3ee7SMikulas Patocka 26531da177e4SLinus Torvalds return 0; 2654599cdf3bSMikulas Patocka 2655599cdf3bSMikulas Patocka bad_open: 2656599cdf3bSMikulas Patocka kfree(o); 2657599cdf3bSMikulas Patocka bad_alloc: 2658599cdf3bSMikulas Patocka return r; 26591da177e4SLinus Torvalds } 26601da177e4SLinus Torvalds 26611da177e4SLinus Torvalds static void origin_dtr(struct dm_target *ti) 26621da177e4SLinus Torvalds { 2663599cdf3bSMikulas Patocka struct dm_origin *o = ti->private; 2664b735fedeSMikulas Patocka 2665599cdf3bSMikulas Patocka dm_put_device(ti, o->dev); 2666599cdf3bSMikulas Patocka kfree(o); 26671da177e4SLinus Torvalds } 26681da177e4SLinus Torvalds 26697de3ee57SMikulas Patocka static int origin_map(struct dm_target *ti, struct bio *bio) 26701da177e4SLinus Torvalds { 2671599cdf3bSMikulas Patocka struct dm_origin *o = ti->private; 267286a3238cSHeinz Mauelshagen unsigned int available_sectors; 26731da177e4SLinus Torvalds 267474d46992SChristoph Hellwig bio_set_dev(bio, o->dev->bdev); 26751da177e4SLinus Torvalds 26761eff9d32SJens Axboe if (unlikely(bio->bi_opf & REQ_PREFLUSH)) 2677494b3ee7SMikulas Patocka return DM_MAPIO_REMAPPED; 2678494b3ee7SMikulas Patocka 267970246286SChristoph Hellwig if (bio_data_dir(bio) != WRITE) 2680298eaa89SMikulas Patocka return DM_MAPIO_REMAPPED; 2681298eaa89SMikulas Patocka 2682298eaa89SMikulas Patocka available_sectors = o->split_boundary - 268386a3238cSHeinz Mauelshagen ((unsigned int)bio->bi_iter.bi_sector & (o->split_boundary - 1)); 2684298eaa89SMikulas Patocka 2685298eaa89SMikulas Patocka if (bio_sectors(bio) > available_sectors) 2686298eaa89SMikulas Patocka dm_accept_partial_bio(bio, available_sectors); 2687298eaa89SMikulas Patocka 26881da177e4SLinus Torvalds /* Only tell snapshots if this is a write */ 2689b2155578SMikulas Patocka return do_origin(o->dev, bio, true); 26901da177e4SLinus Torvalds } 26911da177e4SLinus Torvalds 26921da177e4SLinus Torvalds /* 2693542f9038SMike Snitzer * Set the target "max_io_len" field to the minimum of all the snapshots' 26941da177e4SLinus Torvalds * chunk sizes. 26951da177e4SLinus Torvalds */ 26961da177e4SLinus Torvalds static void origin_resume(struct dm_target *ti) 26971da177e4SLinus Torvalds { 2698599cdf3bSMikulas Patocka struct dm_origin *o = ti->private; 26991da177e4SLinus Torvalds 2700298eaa89SMikulas Patocka o->split_boundary = get_origin_minimum_chunksize(o->dev->bdev); 2701b735fedeSMikulas Patocka 2702b735fedeSMikulas Patocka down_write(&_origins_lock); 2703b735fedeSMikulas Patocka __insert_dm_origin(o); 2704b735fedeSMikulas Patocka up_write(&_origins_lock); 2705b735fedeSMikulas Patocka } 2706b735fedeSMikulas Patocka 2707b735fedeSMikulas Patocka static void origin_postsuspend(struct dm_target *ti) 2708b735fedeSMikulas Patocka { 2709b735fedeSMikulas Patocka struct dm_origin *o = ti->private; 2710b735fedeSMikulas Patocka 2711b735fedeSMikulas Patocka down_write(&_origins_lock); 2712b735fedeSMikulas Patocka __remove_dm_origin(o); 2713b735fedeSMikulas Patocka up_write(&_origins_lock); 27141da177e4SLinus Torvalds } 27151da177e4SLinus Torvalds 2716fd7c092eSMikulas Patocka static void origin_status(struct dm_target *ti, status_type_t type, 271786a3238cSHeinz Mauelshagen unsigned int status_flags, char *result, unsigned int maxlen) 27181da177e4SLinus Torvalds { 2719599cdf3bSMikulas Patocka struct dm_origin *o = ti->private; 27201da177e4SLinus Torvalds 27211da177e4SLinus Torvalds switch (type) { 27221da177e4SLinus Torvalds case STATUSTYPE_INFO: 27231da177e4SLinus Torvalds result[0] = '\0'; 27241da177e4SLinus Torvalds break; 27251da177e4SLinus Torvalds 27261da177e4SLinus Torvalds case STATUSTYPE_TABLE: 2727599cdf3bSMikulas Patocka snprintf(result, maxlen, "%s", o->dev->name); 27281da177e4SLinus Torvalds break; 27298ec45662STushar Sugandhi case STATUSTYPE_IMA: 27308ec45662STushar Sugandhi result[0] = '\0'; 27318ec45662STushar Sugandhi break; 27321da177e4SLinus Torvalds } 27331da177e4SLinus Torvalds } 27341da177e4SLinus Torvalds 27358811f46cSMike Snitzer static int origin_iterate_devices(struct dm_target *ti, 27368811f46cSMike Snitzer iterate_devices_callout_fn fn, void *data) 27378811f46cSMike Snitzer { 2738599cdf3bSMikulas Patocka struct dm_origin *o = ti->private; 27398811f46cSMike Snitzer 2740599cdf3bSMikulas Patocka return fn(ti, o->dev, 0, ti->len, data); 27418811f46cSMike Snitzer } 27428811f46cSMike Snitzer 27431da177e4SLinus Torvalds static struct target_type origin_target = { 27441da177e4SLinus Torvalds .name = "snapshot-origin", 2745b735fedeSMikulas Patocka .version = {1, 9, 0}, 27461da177e4SLinus Torvalds .module = THIS_MODULE, 27471da177e4SLinus Torvalds .ctr = origin_ctr, 27481da177e4SLinus Torvalds .dtr = origin_dtr, 27491da177e4SLinus Torvalds .map = origin_map, 27501da177e4SLinus Torvalds .resume = origin_resume, 2751b735fedeSMikulas Patocka .postsuspend = origin_postsuspend, 27521da177e4SLinus Torvalds .status = origin_status, 27538811f46cSMike Snitzer .iterate_devices = origin_iterate_devices, 27541da177e4SLinus Torvalds }; 27551da177e4SLinus Torvalds 27561da177e4SLinus Torvalds static struct target_type snapshot_target = { 27571da177e4SLinus Torvalds .name = "snapshot", 27582e602385SMike Snitzer .version = {1, 16, 0}, 27591da177e4SLinus Torvalds .module = THIS_MODULE, 27601da177e4SLinus Torvalds .ctr = snapshot_ctr, 27611da177e4SLinus Torvalds .dtr = snapshot_dtr, 27621da177e4SLinus Torvalds .map = snapshot_map, 2763cd45daffSMikulas Patocka .end_io = snapshot_end_io, 2764c1f0c183SMike Snitzer .preresume = snapshot_preresume, 27651da177e4SLinus Torvalds .resume = snapshot_resume, 27661da177e4SLinus Torvalds .status = snapshot_status, 27678811f46cSMike Snitzer .iterate_devices = snapshot_iterate_devices, 27682e602385SMike Snitzer .io_hints = snapshot_io_hints, 27691da177e4SLinus Torvalds }; 27701da177e4SLinus Torvalds 2771d698aa45SMikulas Patocka static struct target_type merge_target = { 2772d698aa45SMikulas Patocka .name = dm_snapshot_merge_target_name, 27732e602385SMike Snitzer .version = {1, 5, 0}, 2774d698aa45SMikulas Patocka .module = THIS_MODULE, 2775d698aa45SMikulas Patocka .ctr = snapshot_ctr, 2776d698aa45SMikulas Patocka .dtr = snapshot_dtr, 27773452c2a1SMikulas Patocka .map = snapshot_merge_map, 2778d698aa45SMikulas Patocka .end_io = snapshot_end_io, 27791e03f97eSMikulas Patocka .presuspend = snapshot_merge_presuspend, 2780d698aa45SMikulas Patocka .preresume = snapshot_preresume, 27811e03f97eSMikulas Patocka .resume = snapshot_merge_resume, 2782d698aa45SMikulas Patocka .status = snapshot_status, 2783d698aa45SMikulas Patocka .iterate_devices = snapshot_iterate_devices, 27842e602385SMike Snitzer .io_hints = snapshot_io_hints, 2785d698aa45SMikulas Patocka }; 2786d698aa45SMikulas Patocka 27871da177e4SLinus Torvalds static int __init dm_snapshot_init(void) 27881da177e4SLinus Torvalds { 27891da177e4SLinus Torvalds int r; 27901da177e4SLinus Torvalds 27914db6bfe0SAlasdair G Kergon r = dm_exception_store_init(); 27924db6bfe0SAlasdair G Kergon if (r) { 27934db6bfe0SAlasdair G Kergon DMERR("Failed to initialize exception stores"); 27944db6bfe0SAlasdair G Kergon return r; 27954db6bfe0SAlasdair G Kergon } 27964db6bfe0SAlasdair G Kergon 27971da177e4SLinus Torvalds r = init_origin_hash(); 27981da177e4SLinus Torvalds if (r) { 27991da177e4SLinus Torvalds DMERR("init_origin_hash failed."); 2800d698aa45SMikulas Patocka goto bad_origin_hash; 28011da177e4SLinus Torvalds } 28021da177e4SLinus Torvalds 28031d4989c8SJon Brassow exception_cache = KMEM_CACHE(dm_exception, 0); 28041da177e4SLinus Torvalds if (!exception_cache) { 28051da177e4SLinus Torvalds DMERR("Couldn't create exception cache."); 28061da177e4SLinus Torvalds r = -ENOMEM; 2807d698aa45SMikulas Patocka goto bad_exception_cache; 28081da177e4SLinus Torvalds } 28091da177e4SLinus Torvalds 2810028867acSAlasdair G Kergon pending_cache = KMEM_CACHE(dm_snap_pending_exception, 0); 28111da177e4SLinus Torvalds if (!pending_cache) { 28121da177e4SLinus Torvalds DMERR("Couldn't create pending cache."); 28131da177e4SLinus Torvalds r = -ENOMEM; 2814d698aa45SMikulas Patocka goto bad_pending_cache; 28151da177e4SLinus Torvalds } 28161da177e4SLinus Torvalds 28177e6358d2Smonty_pavel@sina.com r = dm_register_target(&snapshot_target); 28187e6358d2Smonty_pavel@sina.com if (r < 0) { 28197e6358d2Smonty_pavel@sina.com DMERR("snapshot target register failed %d", r); 28207e6358d2Smonty_pavel@sina.com goto bad_register_snapshot_target; 28217e6358d2Smonty_pavel@sina.com } 28227e6358d2Smonty_pavel@sina.com 28237e6358d2Smonty_pavel@sina.com r = dm_register_target(&origin_target); 28247e6358d2Smonty_pavel@sina.com if (r < 0) { 28257e6358d2Smonty_pavel@sina.com DMERR("Origin target register failed %d", r); 28267e6358d2Smonty_pavel@sina.com goto bad_register_origin_target; 28277e6358d2Smonty_pavel@sina.com } 28287e6358d2Smonty_pavel@sina.com 28297e6358d2Smonty_pavel@sina.com r = dm_register_target(&merge_target); 28307e6358d2Smonty_pavel@sina.com if (r < 0) { 28317e6358d2Smonty_pavel@sina.com DMERR("Merge target register failed %d", r); 28327e6358d2Smonty_pavel@sina.com goto bad_register_merge_target; 28337e6358d2Smonty_pavel@sina.com } 28347e6358d2Smonty_pavel@sina.com 28351da177e4SLinus Torvalds return 0; 28361da177e4SLinus Torvalds 2837d698aa45SMikulas Patocka bad_register_merge_target: 28381da177e4SLinus Torvalds dm_unregister_target(&origin_target); 2839d698aa45SMikulas Patocka bad_register_origin_target: 28401da177e4SLinus Torvalds dm_unregister_target(&snapshot_target); 2841034a186dSJonathan Brassow bad_register_snapshot_target: 28427e6358d2Smonty_pavel@sina.com kmem_cache_destroy(pending_cache); 28437e6358d2Smonty_pavel@sina.com bad_pending_cache: 28447e6358d2Smonty_pavel@sina.com kmem_cache_destroy(exception_cache); 28457e6358d2Smonty_pavel@sina.com bad_exception_cache: 28467e6358d2Smonty_pavel@sina.com exit_origin_hash(); 28477e6358d2Smonty_pavel@sina.com bad_origin_hash: 2848034a186dSJonathan Brassow dm_exception_store_exit(); 2849d698aa45SMikulas Patocka 28501da177e4SLinus Torvalds return r; 28511da177e4SLinus Torvalds } 28521da177e4SLinus Torvalds 28531da177e4SLinus Torvalds static void __exit dm_snapshot_exit(void) 28541da177e4SLinus Torvalds { 285510d3bd09SMikulas Patocka dm_unregister_target(&snapshot_target); 285610d3bd09SMikulas Patocka dm_unregister_target(&origin_target); 2857d698aa45SMikulas Patocka dm_unregister_target(&merge_target); 28581da177e4SLinus Torvalds 28591da177e4SLinus Torvalds exit_origin_hash(); 28601da177e4SLinus Torvalds kmem_cache_destroy(pending_cache); 28611da177e4SLinus Torvalds kmem_cache_destroy(exception_cache); 28624db6bfe0SAlasdair G Kergon 28634db6bfe0SAlasdair G Kergon dm_exception_store_exit(); 28641da177e4SLinus Torvalds } 28651da177e4SLinus Torvalds 28661da177e4SLinus Torvalds /* Module hooks */ 28671da177e4SLinus Torvalds module_init(dm_snapshot_init); 28681da177e4SLinus Torvalds module_exit(dm_snapshot_exit); 28691da177e4SLinus Torvalds 28701da177e4SLinus Torvalds MODULE_DESCRIPTION(DM_NAME " snapshot target"); 28711da177e4SLinus Torvalds MODULE_AUTHOR("Joe Thornber"); 28721da177e4SLinus Torvalds MODULE_LICENSE("GPL"); 287323cb2109SMikulas Patocka MODULE_ALIAS("dm-snapshot-origin"); 287423cb2109SMikulas Patocka MODULE_ALIAS("dm-snapshot-merge"); 2875