11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * dm-snapshot.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 2001-2002 Sistina Software (UK) Limited. 51da177e4SLinus Torvalds * 61da177e4SLinus Torvalds * This file is released under the GPL. 71da177e4SLinus Torvalds */ 81da177e4SLinus Torvalds 91da177e4SLinus Torvalds #include <linux/blkdev.h> 101da177e4SLinus Torvalds #include <linux/device-mapper.h> 1190fa1527SMikulas Patocka #include <linux/delay.h> 121da177e4SLinus Torvalds #include <linux/fs.h> 131da177e4SLinus Torvalds #include <linux/init.h> 141da177e4SLinus Torvalds #include <linux/kdev_t.h> 151da177e4SLinus Torvalds #include <linux/list.h> 161da177e4SLinus Torvalds #include <linux/mempool.h> 171da177e4SLinus Torvalds #include <linux/module.h> 181da177e4SLinus Torvalds #include <linux/slab.h> 191da177e4SLinus Torvalds #include <linux/vmalloc.h> 206f3c3f0aSvignesh babu #include <linux/log2.h> 21a765e20eSAlasdair G Kergon #include <linux/dm-kcopyd.h> 221da177e4SLinus Torvalds 23aea53d92SJonathan Brassow #include "dm-exception-store.h" 241da177e4SLinus Torvalds 2572d94861SAlasdair G Kergon #define DM_MSG_PREFIX "snapshots" 2672d94861SAlasdair G Kergon 27d698aa45SMikulas Patocka static const char dm_snapshot_merge_target_name[] = "snapshot-merge"; 28d698aa45SMikulas Patocka 29d698aa45SMikulas Patocka #define dm_target_is_snapshot_merge(ti) \ 30d698aa45SMikulas Patocka ((ti)->type->name == dm_snapshot_merge_target_name) 31d698aa45SMikulas Patocka 321da177e4SLinus Torvalds /* 33cd45daffSMikulas Patocka * The size of the mempool used to track chunks in use. 34cd45daffSMikulas Patocka */ 35cd45daffSMikulas Patocka #define MIN_IOS 256 36cd45daffSMikulas Patocka 37ccc45ea8SJonathan Brassow #define DM_TRACKED_CHUNK_HASH_SIZE 16 38ccc45ea8SJonathan Brassow #define DM_TRACKED_CHUNK_HASH(x) ((unsigned long)(x) & \ 39ccc45ea8SJonathan Brassow (DM_TRACKED_CHUNK_HASH_SIZE - 1)) 40ccc45ea8SJonathan Brassow 41191437a5SJon Brassow struct dm_exception_table { 42ccc45ea8SJonathan Brassow uint32_t hash_mask; 43ccc45ea8SJonathan Brassow unsigned hash_shift; 44ccc45ea8SJonathan Brassow struct list_head *table; 45ccc45ea8SJonathan Brassow }; 46ccc45ea8SJonathan Brassow 47ccc45ea8SJonathan Brassow struct dm_snapshot { 48ccc45ea8SJonathan Brassow struct rw_semaphore lock; 49ccc45ea8SJonathan Brassow 50ccc45ea8SJonathan Brassow struct dm_dev *origin; 51fc56f6fbSMike Snitzer struct dm_dev *cow; 52fc56f6fbSMike Snitzer 53fc56f6fbSMike Snitzer struct dm_target *ti; 54ccc45ea8SJonathan Brassow 55ccc45ea8SJonathan Brassow /* List of snapshots per Origin */ 56ccc45ea8SJonathan Brassow struct list_head list; 57ccc45ea8SJonathan Brassow 58d8ddb1cfSMike Snitzer /* 59d8ddb1cfSMike Snitzer * You can't use a snapshot if this is 0 (e.g. if full). 60d8ddb1cfSMike Snitzer * A snapshot-merge target never clears this. 61d8ddb1cfSMike Snitzer */ 62ccc45ea8SJonathan Brassow int valid; 63ccc45ea8SJonathan Brassow 64ccc45ea8SJonathan Brassow /* Origin writes don't trigger exceptions until this is set */ 65ccc45ea8SJonathan Brassow int active; 66ccc45ea8SJonathan Brassow 67ccc45ea8SJonathan Brassow atomic_t pending_exceptions_count; 68ccc45ea8SJonathan Brassow 69924e600dSMike Snitzer mempool_t *pending_pool; 70924e600dSMike Snitzer 71191437a5SJon Brassow struct dm_exception_table pending; 72191437a5SJon Brassow struct dm_exception_table complete; 73ccc45ea8SJonathan Brassow 74ccc45ea8SJonathan Brassow /* 75ccc45ea8SJonathan Brassow * pe_lock protects all pending_exception operations and access 76ccc45ea8SJonathan Brassow * as well as the snapshot_bios list. 77ccc45ea8SJonathan Brassow */ 78ccc45ea8SJonathan Brassow spinlock_t pe_lock; 79ccc45ea8SJonathan Brassow 80924e600dSMike Snitzer /* Chunks with outstanding reads */ 81924e600dSMike Snitzer spinlock_t tracked_chunk_lock; 82924e600dSMike Snitzer mempool_t *tracked_chunk_pool; 83924e600dSMike Snitzer struct hlist_head tracked_chunk_hash[DM_TRACKED_CHUNK_HASH_SIZE]; 84924e600dSMike Snitzer 85ccc45ea8SJonathan Brassow /* The on disk metadata handler */ 86ccc45ea8SJonathan Brassow struct dm_exception_store *store; 87ccc45ea8SJonathan Brassow 88ccc45ea8SJonathan Brassow struct dm_kcopyd_client *kcopyd_client; 89ccc45ea8SJonathan Brassow 90924e600dSMike Snitzer /* Wait for events based on state_bits */ 91924e600dSMike Snitzer unsigned long state_bits; 92924e600dSMike Snitzer 93924e600dSMike Snitzer /* Range of chunks currently being merged. */ 94924e600dSMike Snitzer chunk_t first_merging_chunk; 95924e600dSMike Snitzer int num_merging_chunks; 961e03f97eSMikulas Patocka 97d8ddb1cfSMike Snitzer /* 98d8ddb1cfSMike Snitzer * The merge operation failed if this flag is set. 99d8ddb1cfSMike Snitzer * Failure modes are handled as follows: 100d8ddb1cfSMike Snitzer * - I/O error reading the header 101d8ddb1cfSMike Snitzer * => don't load the target; abort. 102d8ddb1cfSMike Snitzer * - Header does not have "valid" flag set 103d8ddb1cfSMike Snitzer * => use the origin; forget about the snapshot. 104d8ddb1cfSMike Snitzer * - I/O error when reading exceptions 105d8ddb1cfSMike Snitzer * => don't load the target; abort. 106d8ddb1cfSMike Snitzer * (We can't use the intermediate origin state.) 107d8ddb1cfSMike Snitzer * - I/O error while merging 108d8ddb1cfSMike Snitzer * => stop merging; set merge_failed; process I/O normally. 109d8ddb1cfSMike Snitzer */ 110d8ddb1cfSMike Snitzer int merge_failed; 111d8ddb1cfSMike Snitzer 1129fe86254SMikulas Patocka /* 1139fe86254SMikulas Patocka * Incoming bios that overlap with chunks being merged must wait 1149fe86254SMikulas Patocka * for them to be committed. 1159fe86254SMikulas Patocka */ 1169fe86254SMikulas Patocka struct bio_list bios_queued_during_merge; 117ccc45ea8SJonathan Brassow }; 118ccc45ea8SJonathan Brassow 1191e03f97eSMikulas Patocka /* 1201e03f97eSMikulas Patocka * state_bits: 1211e03f97eSMikulas Patocka * RUNNING_MERGE - Merge operation is in progress. 1221e03f97eSMikulas Patocka * SHUTDOWN_MERGE - Set to signal that merge needs to be stopped; 1231e03f97eSMikulas Patocka * cleared afterwards. 1241e03f97eSMikulas Patocka */ 1251e03f97eSMikulas Patocka #define RUNNING_MERGE 0 1261e03f97eSMikulas Patocka #define SHUTDOWN_MERGE 1 1271e03f97eSMikulas Patocka 128c2411045SMikulas Patocka struct dm_dev *dm_snap_origin(struct dm_snapshot *s) 129c2411045SMikulas Patocka { 130c2411045SMikulas Patocka return s->origin; 131c2411045SMikulas Patocka } 132c2411045SMikulas Patocka EXPORT_SYMBOL(dm_snap_origin); 133c2411045SMikulas Patocka 134fc56f6fbSMike Snitzer struct dm_dev *dm_snap_cow(struct dm_snapshot *s) 135fc56f6fbSMike Snitzer { 136fc56f6fbSMike Snitzer return s->cow; 137fc56f6fbSMike Snitzer } 138fc56f6fbSMike Snitzer EXPORT_SYMBOL(dm_snap_cow); 139fc56f6fbSMike Snitzer 140ccc45ea8SJonathan Brassow static sector_t chunk_to_sector(struct dm_exception_store *store, 141ccc45ea8SJonathan Brassow chunk_t chunk) 142ccc45ea8SJonathan Brassow { 143ccc45ea8SJonathan Brassow return chunk << store->chunk_shift; 144ccc45ea8SJonathan Brassow } 145ccc45ea8SJonathan Brassow 146ccc45ea8SJonathan Brassow static int bdev_equal(struct block_device *lhs, struct block_device *rhs) 147ccc45ea8SJonathan Brassow { 148ccc45ea8SJonathan Brassow /* 149ccc45ea8SJonathan Brassow * There is only ever one instance of a particular block 150ccc45ea8SJonathan Brassow * device so we can compare pointers safely. 151ccc45ea8SJonathan Brassow */ 152ccc45ea8SJonathan Brassow return lhs == rhs; 153ccc45ea8SJonathan Brassow } 154ccc45ea8SJonathan Brassow 155028867acSAlasdair G Kergon struct dm_snap_pending_exception { 1561d4989c8SJon Brassow struct dm_exception e; 1571da177e4SLinus Torvalds 1581da177e4SLinus Torvalds /* 1591da177e4SLinus Torvalds * Origin buffers waiting for this to complete are held 1601da177e4SLinus Torvalds * in a bio list 1611da177e4SLinus Torvalds */ 1621da177e4SLinus Torvalds struct bio_list origin_bios; 1631da177e4SLinus Torvalds struct bio_list snapshot_bios; 1641da177e4SLinus Torvalds 1651da177e4SLinus Torvalds /* Pointer back to snapshot context */ 1661da177e4SLinus Torvalds struct dm_snapshot *snap; 1671da177e4SLinus Torvalds 1681da177e4SLinus Torvalds /* 1691da177e4SLinus Torvalds * 1 indicates the exception has already been sent to 1701da177e4SLinus Torvalds * kcopyd. 1711da177e4SLinus Torvalds */ 1721da177e4SLinus Torvalds int started; 173a6e50b40SMikulas Patocka 174a6e50b40SMikulas Patocka /* 175a6e50b40SMikulas Patocka * For writing a complete chunk, bypassing the copy. 176a6e50b40SMikulas Patocka */ 177a6e50b40SMikulas Patocka struct bio *full_bio; 178a6e50b40SMikulas Patocka bio_end_io_t *full_bio_end_io; 179a6e50b40SMikulas Patocka void *full_bio_private; 1801da177e4SLinus Torvalds }; 1811da177e4SLinus Torvalds 1821da177e4SLinus Torvalds /* 1831da177e4SLinus Torvalds * Hash table mapping origin volumes to lists of snapshots and 1841da177e4SLinus Torvalds * a lock to protect it 1851da177e4SLinus Torvalds */ 186e18b890bSChristoph Lameter static struct kmem_cache *exception_cache; 187e18b890bSChristoph Lameter static struct kmem_cache *pending_cache; 1881da177e4SLinus Torvalds 189cd45daffSMikulas Patocka struct dm_snap_tracked_chunk { 190cd45daffSMikulas Patocka struct hlist_node node; 191cd45daffSMikulas Patocka chunk_t chunk; 192cd45daffSMikulas Patocka }; 193cd45daffSMikulas Patocka 194cd45daffSMikulas Patocka static struct kmem_cache *tracked_chunk_cache; 195cd45daffSMikulas Patocka 196cd45daffSMikulas Patocka static struct dm_snap_tracked_chunk *track_chunk(struct dm_snapshot *s, 197cd45daffSMikulas Patocka chunk_t chunk) 198cd45daffSMikulas Patocka { 199cd45daffSMikulas Patocka struct dm_snap_tracked_chunk *c = mempool_alloc(s->tracked_chunk_pool, 200cd45daffSMikulas Patocka GFP_NOIO); 201cd45daffSMikulas Patocka unsigned long flags; 202cd45daffSMikulas Patocka 203cd45daffSMikulas Patocka c->chunk = chunk; 204cd45daffSMikulas Patocka 205cd45daffSMikulas Patocka spin_lock_irqsave(&s->tracked_chunk_lock, flags); 206cd45daffSMikulas Patocka hlist_add_head(&c->node, 207cd45daffSMikulas Patocka &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)]); 208cd45daffSMikulas Patocka spin_unlock_irqrestore(&s->tracked_chunk_lock, flags); 209cd45daffSMikulas Patocka 210cd45daffSMikulas Patocka return c; 211cd45daffSMikulas Patocka } 212cd45daffSMikulas Patocka 213cd45daffSMikulas Patocka static void stop_tracking_chunk(struct dm_snapshot *s, 214cd45daffSMikulas Patocka struct dm_snap_tracked_chunk *c) 215cd45daffSMikulas Patocka { 216cd45daffSMikulas Patocka unsigned long flags; 217cd45daffSMikulas Patocka 218cd45daffSMikulas Patocka spin_lock_irqsave(&s->tracked_chunk_lock, flags); 219cd45daffSMikulas Patocka hlist_del(&c->node); 220cd45daffSMikulas Patocka spin_unlock_irqrestore(&s->tracked_chunk_lock, flags); 221cd45daffSMikulas Patocka 222cd45daffSMikulas Patocka mempool_free(c, s->tracked_chunk_pool); 223cd45daffSMikulas Patocka } 224cd45daffSMikulas Patocka 225a8d41b59SMikulas Patocka static int __chunk_is_tracked(struct dm_snapshot *s, chunk_t chunk) 226a8d41b59SMikulas Patocka { 227a8d41b59SMikulas Patocka struct dm_snap_tracked_chunk *c; 228a8d41b59SMikulas Patocka struct hlist_node *hn; 229a8d41b59SMikulas Patocka int found = 0; 230a8d41b59SMikulas Patocka 231a8d41b59SMikulas Patocka spin_lock_irq(&s->tracked_chunk_lock); 232a8d41b59SMikulas Patocka 233a8d41b59SMikulas Patocka hlist_for_each_entry(c, hn, 234a8d41b59SMikulas Patocka &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)], node) { 235a8d41b59SMikulas Patocka if (c->chunk == chunk) { 236a8d41b59SMikulas Patocka found = 1; 237a8d41b59SMikulas Patocka break; 238a8d41b59SMikulas Patocka } 239a8d41b59SMikulas Patocka } 240a8d41b59SMikulas Patocka 241a8d41b59SMikulas Patocka spin_unlock_irq(&s->tracked_chunk_lock); 242a8d41b59SMikulas Patocka 243a8d41b59SMikulas Patocka return found; 244a8d41b59SMikulas Patocka } 245a8d41b59SMikulas Patocka 2461da177e4SLinus Torvalds /* 247615d1eb9SMike Snitzer * This conflicting I/O is extremely improbable in the caller, 248615d1eb9SMike Snitzer * so msleep(1) is sufficient and there is no need for a wait queue. 249615d1eb9SMike Snitzer */ 250615d1eb9SMike Snitzer static void __check_for_conflicting_io(struct dm_snapshot *s, chunk_t chunk) 251615d1eb9SMike Snitzer { 252615d1eb9SMike Snitzer while (__chunk_is_tracked(s, chunk)) 253615d1eb9SMike Snitzer msleep(1); 254615d1eb9SMike Snitzer } 255615d1eb9SMike Snitzer 256615d1eb9SMike Snitzer /* 2571da177e4SLinus Torvalds * One of these per registered origin, held in the snapshot_origins hash 2581da177e4SLinus Torvalds */ 2591da177e4SLinus Torvalds struct origin { 2601da177e4SLinus Torvalds /* The origin device */ 2611da177e4SLinus Torvalds struct block_device *bdev; 2621da177e4SLinus Torvalds 2631da177e4SLinus Torvalds struct list_head hash_list; 2641da177e4SLinus Torvalds 2651da177e4SLinus Torvalds /* List of snapshots for this origin */ 2661da177e4SLinus Torvalds struct list_head snapshots; 2671da177e4SLinus Torvalds }; 2681da177e4SLinus Torvalds 2691da177e4SLinus Torvalds /* 2701da177e4SLinus Torvalds * Size of the hash table for origin volumes. If we make this 2711da177e4SLinus Torvalds * the size of the minors list then it should be nearly perfect 2721da177e4SLinus Torvalds */ 2731da177e4SLinus Torvalds #define ORIGIN_HASH_SIZE 256 2741da177e4SLinus Torvalds #define ORIGIN_MASK 0xFF 2751da177e4SLinus Torvalds static struct list_head *_origins; 2761da177e4SLinus Torvalds static struct rw_semaphore _origins_lock; 2771da177e4SLinus Torvalds 27873dfd078SMikulas Patocka static DECLARE_WAIT_QUEUE_HEAD(_pending_exceptions_done); 27973dfd078SMikulas Patocka static DEFINE_SPINLOCK(_pending_exceptions_done_spinlock); 28073dfd078SMikulas Patocka static uint64_t _pending_exceptions_done_count; 28173dfd078SMikulas Patocka 2821da177e4SLinus Torvalds static int init_origin_hash(void) 2831da177e4SLinus Torvalds { 2841da177e4SLinus Torvalds int i; 2851da177e4SLinus Torvalds 2861da177e4SLinus Torvalds _origins = kmalloc(ORIGIN_HASH_SIZE * sizeof(struct list_head), 2871da177e4SLinus Torvalds GFP_KERNEL); 2881da177e4SLinus Torvalds if (!_origins) { 28972d94861SAlasdair G Kergon DMERR("unable to allocate memory"); 2901da177e4SLinus Torvalds return -ENOMEM; 2911da177e4SLinus Torvalds } 2921da177e4SLinus Torvalds 2931da177e4SLinus Torvalds for (i = 0; i < ORIGIN_HASH_SIZE; i++) 2941da177e4SLinus Torvalds INIT_LIST_HEAD(_origins + i); 2951da177e4SLinus Torvalds init_rwsem(&_origins_lock); 2961da177e4SLinus Torvalds 2971da177e4SLinus Torvalds return 0; 2981da177e4SLinus Torvalds } 2991da177e4SLinus Torvalds 3001da177e4SLinus Torvalds static void exit_origin_hash(void) 3011da177e4SLinus Torvalds { 3021da177e4SLinus Torvalds kfree(_origins); 3031da177e4SLinus Torvalds } 3041da177e4SLinus Torvalds 305028867acSAlasdair G Kergon static unsigned origin_hash(struct block_device *bdev) 3061da177e4SLinus Torvalds { 3071da177e4SLinus Torvalds return bdev->bd_dev & ORIGIN_MASK; 3081da177e4SLinus Torvalds } 3091da177e4SLinus Torvalds 3101da177e4SLinus Torvalds static struct origin *__lookup_origin(struct block_device *origin) 3111da177e4SLinus Torvalds { 3121da177e4SLinus Torvalds struct list_head *ol; 3131da177e4SLinus Torvalds struct origin *o; 3141da177e4SLinus Torvalds 3151da177e4SLinus Torvalds ol = &_origins[origin_hash(origin)]; 3161da177e4SLinus Torvalds list_for_each_entry (o, ol, hash_list) 3171da177e4SLinus Torvalds if (bdev_equal(o->bdev, origin)) 3181da177e4SLinus Torvalds return o; 3191da177e4SLinus Torvalds 3201da177e4SLinus Torvalds return NULL; 3211da177e4SLinus Torvalds } 3221da177e4SLinus Torvalds 3231da177e4SLinus Torvalds static void __insert_origin(struct origin *o) 3241da177e4SLinus Torvalds { 3251da177e4SLinus Torvalds struct list_head *sl = &_origins[origin_hash(o->bdev)]; 3261da177e4SLinus Torvalds list_add_tail(&o->hash_list, sl); 3271da177e4SLinus Torvalds } 3281da177e4SLinus Torvalds 3291da177e4SLinus Torvalds /* 330c1f0c183SMike Snitzer * _origins_lock must be held when calling this function. 331c1f0c183SMike Snitzer * Returns number of snapshots registered using the supplied cow device, plus: 332c1f0c183SMike Snitzer * snap_src - a snapshot suitable for use as a source of exception handover 333c1f0c183SMike Snitzer * snap_dest - a snapshot capable of receiving exception handover. 3349d3b15c4SMikulas Patocka * snap_merge - an existing snapshot-merge target linked to the same origin. 3359d3b15c4SMikulas Patocka * There can be at most one snapshot-merge target. The parameter is optional. 336c1f0c183SMike Snitzer * 3379d3b15c4SMikulas Patocka * Possible return values and states of snap_src and snap_dest. 338c1f0c183SMike Snitzer * 0: NULL, NULL - first new snapshot 339c1f0c183SMike Snitzer * 1: snap_src, NULL - normal snapshot 340c1f0c183SMike Snitzer * 2: snap_src, snap_dest - waiting for handover 341c1f0c183SMike Snitzer * 2: snap_src, NULL - handed over, waiting for old to be deleted 342c1f0c183SMike Snitzer * 1: NULL, snap_dest - source got destroyed without handover 343c1f0c183SMike Snitzer */ 344c1f0c183SMike Snitzer static int __find_snapshots_sharing_cow(struct dm_snapshot *snap, 345c1f0c183SMike Snitzer struct dm_snapshot **snap_src, 3469d3b15c4SMikulas Patocka struct dm_snapshot **snap_dest, 3479d3b15c4SMikulas Patocka struct dm_snapshot **snap_merge) 348c1f0c183SMike Snitzer { 349c1f0c183SMike Snitzer struct dm_snapshot *s; 350c1f0c183SMike Snitzer struct origin *o; 351c1f0c183SMike Snitzer int count = 0; 352c1f0c183SMike Snitzer int active; 353c1f0c183SMike Snitzer 354c1f0c183SMike Snitzer o = __lookup_origin(snap->origin->bdev); 355c1f0c183SMike Snitzer if (!o) 356c1f0c183SMike Snitzer goto out; 357c1f0c183SMike Snitzer 358c1f0c183SMike Snitzer list_for_each_entry(s, &o->snapshots, list) { 3599d3b15c4SMikulas Patocka if (dm_target_is_snapshot_merge(s->ti) && snap_merge) 3609d3b15c4SMikulas Patocka *snap_merge = s; 361c1f0c183SMike Snitzer if (!bdev_equal(s->cow->bdev, snap->cow->bdev)) 362c1f0c183SMike Snitzer continue; 363c1f0c183SMike Snitzer 364c1f0c183SMike Snitzer down_read(&s->lock); 365c1f0c183SMike Snitzer active = s->active; 366c1f0c183SMike Snitzer up_read(&s->lock); 367c1f0c183SMike Snitzer 368c1f0c183SMike Snitzer if (active) { 369c1f0c183SMike Snitzer if (snap_src) 370c1f0c183SMike Snitzer *snap_src = s; 371c1f0c183SMike Snitzer } else if (snap_dest) 372c1f0c183SMike Snitzer *snap_dest = s; 373c1f0c183SMike Snitzer 374c1f0c183SMike Snitzer count++; 375c1f0c183SMike Snitzer } 376c1f0c183SMike Snitzer 377c1f0c183SMike Snitzer out: 378c1f0c183SMike Snitzer return count; 379c1f0c183SMike Snitzer } 380c1f0c183SMike Snitzer 381c1f0c183SMike Snitzer /* 382c1f0c183SMike Snitzer * On success, returns 1 if this snapshot is a handover destination, 383c1f0c183SMike Snitzer * otherwise returns 0. 384c1f0c183SMike Snitzer */ 385c1f0c183SMike Snitzer static int __validate_exception_handover(struct dm_snapshot *snap) 386c1f0c183SMike Snitzer { 387c1f0c183SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 3889d3b15c4SMikulas Patocka struct dm_snapshot *snap_merge = NULL; 389c1f0c183SMike Snitzer 390c1f0c183SMike Snitzer /* Does snapshot need exceptions handed over to it? */ 3919d3b15c4SMikulas Patocka if ((__find_snapshots_sharing_cow(snap, &snap_src, &snap_dest, 3929d3b15c4SMikulas Patocka &snap_merge) == 2) || 393c1f0c183SMike Snitzer snap_dest) { 394c1f0c183SMike Snitzer snap->ti->error = "Snapshot cow pairing for exception " 395c1f0c183SMike Snitzer "table handover failed"; 396c1f0c183SMike Snitzer return -EINVAL; 397c1f0c183SMike Snitzer } 398c1f0c183SMike Snitzer 399c1f0c183SMike Snitzer /* 400c1f0c183SMike Snitzer * If no snap_src was found, snap cannot become a handover 401c1f0c183SMike Snitzer * destination. 402c1f0c183SMike Snitzer */ 403c1f0c183SMike Snitzer if (!snap_src) 404c1f0c183SMike Snitzer return 0; 405c1f0c183SMike Snitzer 4069d3b15c4SMikulas Patocka /* 4079d3b15c4SMikulas Patocka * Non-snapshot-merge handover? 4089d3b15c4SMikulas Patocka */ 4099d3b15c4SMikulas Patocka if (!dm_target_is_snapshot_merge(snap->ti)) 4109d3b15c4SMikulas Patocka return 1; 4119d3b15c4SMikulas Patocka 4129d3b15c4SMikulas Patocka /* 4139d3b15c4SMikulas Patocka * Do not allow more than one merging snapshot. 4149d3b15c4SMikulas Patocka */ 4159d3b15c4SMikulas Patocka if (snap_merge) { 4169d3b15c4SMikulas Patocka snap->ti->error = "A snapshot is already merging."; 4179d3b15c4SMikulas Patocka return -EINVAL; 4189d3b15c4SMikulas Patocka } 4199d3b15c4SMikulas Patocka 4201e03f97eSMikulas Patocka if (!snap_src->store->type->prepare_merge || 4211e03f97eSMikulas Patocka !snap_src->store->type->commit_merge) { 4221e03f97eSMikulas Patocka snap->ti->error = "Snapshot exception store does not " 4231e03f97eSMikulas Patocka "support snapshot-merge."; 4241e03f97eSMikulas Patocka return -EINVAL; 4251e03f97eSMikulas Patocka } 4261e03f97eSMikulas Patocka 427c1f0c183SMike Snitzer return 1; 428c1f0c183SMike Snitzer } 429c1f0c183SMike Snitzer 430c1f0c183SMike Snitzer static void __insert_snapshot(struct origin *o, struct dm_snapshot *s) 431c1f0c183SMike Snitzer { 432c1f0c183SMike Snitzer struct dm_snapshot *l; 433c1f0c183SMike Snitzer 434c1f0c183SMike Snitzer /* Sort the list according to chunk size, largest-first smallest-last */ 435c1f0c183SMike Snitzer list_for_each_entry(l, &o->snapshots, list) 436c1f0c183SMike Snitzer if (l->store->chunk_size < s->store->chunk_size) 437c1f0c183SMike Snitzer break; 438c1f0c183SMike Snitzer list_add_tail(&s->list, &l->list); 439c1f0c183SMike Snitzer } 440c1f0c183SMike Snitzer 441c1f0c183SMike Snitzer /* 4421da177e4SLinus Torvalds * Make a note of the snapshot and its origin so we can look it 4431da177e4SLinus Torvalds * up when the origin has a write on it. 444c1f0c183SMike Snitzer * 445c1f0c183SMike Snitzer * Also validate snapshot exception store handovers. 446c1f0c183SMike Snitzer * On success, returns 1 if this registration is a handover destination, 447c1f0c183SMike Snitzer * otherwise returns 0. 4481da177e4SLinus Torvalds */ 4491da177e4SLinus Torvalds static int register_snapshot(struct dm_snapshot *snap) 4501da177e4SLinus Torvalds { 451c1f0c183SMike Snitzer struct origin *o, *new_o = NULL; 4521da177e4SLinus Torvalds struct block_device *bdev = snap->origin->bdev; 453c1f0c183SMike Snitzer int r = 0; 4541da177e4SLinus Torvalds 45560c856c8SMikulas Patocka new_o = kmalloc(sizeof(*new_o), GFP_KERNEL); 45660c856c8SMikulas Patocka if (!new_o) 45760c856c8SMikulas Patocka return -ENOMEM; 45860c856c8SMikulas Patocka 4591da177e4SLinus Torvalds down_write(&_origins_lock); 4601da177e4SLinus Torvalds 461c1f0c183SMike Snitzer r = __validate_exception_handover(snap); 462c1f0c183SMike Snitzer if (r < 0) { 463c1f0c183SMike Snitzer kfree(new_o); 464c1f0c183SMike Snitzer goto out; 465c1f0c183SMike Snitzer } 466c1f0c183SMike Snitzer 467c1f0c183SMike Snitzer o = __lookup_origin(bdev); 46860c856c8SMikulas Patocka if (o) 46960c856c8SMikulas Patocka kfree(new_o); 47060c856c8SMikulas Patocka else { 4711da177e4SLinus Torvalds /* New origin */ 47260c856c8SMikulas Patocka o = new_o; 4731da177e4SLinus Torvalds 4741da177e4SLinus Torvalds /* Initialise the struct */ 4751da177e4SLinus Torvalds INIT_LIST_HEAD(&o->snapshots); 4761da177e4SLinus Torvalds o->bdev = bdev; 4771da177e4SLinus Torvalds 4781da177e4SLinus Torvalds __insert_origin(o); 4791da177e4SLinus Torvalds } 4801da177e4SLinus Torvalds 481c1f0c183SMike Snitzer __insert_snapshot(o, snap); 482c1f0c183SMike Snitzer 483c1f0c183SMike Snitzer out: 484c1f0c183SMike Snitzer up_write(&_origins_lock); 485c1f0c183SMike Snitzer 486c1f0c183SMike Snitzer return r; 487c1f0c183SMike Snitzer } 488c1f0c183SMike Snitzer 489c1f0c183SMike Snitzer /* 490c1f0c183SMike Snitzer * Move snapshot to correct place in list according to chunk size. 491c1f0c183SMike Snitzer */ 492c1f0c183SMike Snitzer static void reregister_snapshot(struct dm_snapshot *s) 493c1f0c183SMike Snitzer { 494c1f0c183SMike Snitzer struct block_device *bdev = s->origin->bdev; 495c1f0c183SMike Snitzer 496c1f0c183SMike Snitzer down_write(&_origins_lock); 497c1f0c183SMike Snitzer 498c1f0c183SMike Snitzer list_del(&s->list); 499c1f0c183SMike Snitzer __insert_snapshot(__lookup_origin(bdev), s); 5001da177e4SLinus Torvalds 5011da177e4SLinus Torvalds up_write(&_origins_lock); 5021da177e4SLinus Torvalds } 5031da177e4SLinus Torvalds 5041da177e4SLinus Torvalds static void unregister_snapshot(struct dm_snapshot *s) 5051da177e4SLinus Torvalds { 5061da177e4SLinus Torvalds struct origin *o; 5071da177e4SLinus Torvalds 5081da177e4SLinus Torvalds down_write(&_origins_lock); 5091da177e4SLinus Torvalds o = __lookup_origin(s->origin->bdev); 5101da177e4SLinus Torvalds 5111da177e4SLinus Torvalds list_del(&s->list); 512c1f0c183SMike Snitzer if (o && list_empty(&o->snapshots)) { 5131da177e4SLinus Torvalds list_del(&o->hash_list); 5141da177e4SLinus Torvalds kfree(o); 5151da177e4SLinus Torvalds } 5161da177e4SLinus Torvalds 5171da177e4SLinus Torvalds up_write(&_origins_lock); 5181da177e4SLinus Torvalds } 5191da177e4SLinus Torvalds 5201da177e4SLinus Torvalds /* 5211da177e4SLinus Torvalds * Implementation of the exception hash tables. 522d74f81f8SMilan Broz * The lowest hash_shift bits of the chunk number are ignored, allowing 523d74f81f8SMilan Broz * some consecutive chunks to be grouped together. 5241da177e4SLinus Torvalds */ 5253510cb94SJon Brassow static int dm_exception_table_init(struct dm_exception_table *et, 5263510cb94SJon Brassow uint32_t size, unsigned hash_shift) 5271da177e4SLinus Torvalds { 5281da177e4SLinus Torvalds unsigned int i; 5291da177e4SLinus Torvalds 530d74f81f8SMilan Broz et->hash_shift = hash_shift; 5311da177e4SLinus Torvalds et->hash_mask = size - 1; 5321da177e4SLinus Torvalds et->table = dm_vcalloc(size, sizeof(struct list_head)); 5331da177e4SLinus Torvalds if (!et->table) 5341da177e4SLinus Torvalds return -ENOMEM; 5351da177e4SLinus Torvalds 5361da177e4SLinus Torvalds for (i = 0; i < size; i++) 5371da177e4SLinus Torvalds INIT_LIST_HEAD(et->table + i); 5381da177e4SLinus Torvalds 5391da177e4SLinus Torvalds return 0; 5401da177e4SLinus Torvalds } 5411da177e4SLinus Torvalds 5423510cb94SJon Brassow static void dm_exception_table_exit(struct dm_exception_table *et, 543191437a5SJon Brassow struct kmem_cache *mem) 5441da177e4SLinus Torvalds { 5451da177e4SLinus Torvalds struct list_head *slot; 5461d4989c8SJon Brassow struct dm_exception *ex, *next; 5471da177e4SLinus Torvalds int i, size; 5481da177e4SLinus Torvalds 5491da177e4SLinus Torvalds size = et->hash_mask + 1; 5501da177e4SLinus Torvalds for (i = 0; i < size; i++) { 5511da177e4SLinus Torvalds slot = et->table + i; 5521da177e4SLinus Torvalds 5531da177e4SLinus Torvalds list_for_each_entry_safe (ex, next, slot, hash_list) 5541da177e4SLinus Torvalds kmem_cache_free(mem, ex); 5551da177e4SLinus Torvalds } 5561da177e4SLinus Torvalds 5571da177e4SLinus Torvalds vfree(et->table); 5581da177e4SLinus Torvalds } 5591da177e4SLinus Torvalds 560191437a5SJon Brassow static uint32_t exception_hash(struct dm_exception_table *et, chunk_t chunk) 5611da177e4SLinus Torvalds { 562d74f81f8SMilan Broz return (chunk >> et->hash_shift) & et->hash_mask; 5631da177e4SLinus Torvalds } 5641da177e4SLinus Torvalds 5653510cb94SJon Brassow static void dm_remove_exception(struct dm_exception *e) 5661da177e4SLinus Torvalds { 5671da177e4SLinus Torvalds list_del(&e->hash_list); 5681da177e4SLinus Torvalds } 5691da177e4SLinus Torvalds 5701da177e4SLinus Torvalds /* 5711da177e4SLinus Torvalds * Return the exception data for a sector, or NULL if not 5721da177e4SLinus Torvalds * remapped. 5731da177e4SLinus Torvalds */ 5743510cb94SJon Brassow static struct dm_exception *dm_lookup_exception(struct dm_exception_table *et, 5751da177e4SLinus Torvalds chunk_t chunk) 5761da177e4SLinus Torvalds { 5771da177e4SLinus Torvalds struct list_head *slot; 5781d4989c8SJon Brassow struct dm_exception *e; 5791da177e4SLinus Torvalds 5801da177e4SLinus Torvalds slot = &et->table[exception_hash(et, chunk)]; 5811da177e4SLinus Torvalds list_for_each_entry (e, slot, hash_list) 582d74f81f8SMilan Broz if (chunk >= e->old_chunk && 583d74f81f8SMilan Broz chunk <= e->old_chunk + dm_consecutive_chunk_count(e)) 5841da177e4SLinus Torvalds return e; 5851da177e4SLinus Torvalds 5861da177e4SLinus Torvalds return NULL; 5871da177e4SLinus Torvalds } 5881da177e4SLinus Torvalds 5893510cb94SJon Brassow static struct dm_exception *alloc_completed_exception(void) 5901da177e4SLinus Torvalds { 5911d4989c8SJon Brassow struct dm_exception *e; 5921da177e4SLinus Torvalds 5931da177e4SLinus Torvalds e = kmem_cache_alloc(exception_cache, GFP_NOIO); 5941da177e4SLinus Torvalds if (!e) 5951da177e4SLinus Torvalds e = kmem_cache_alloc(exception_cache, GFP_ATOMIC); 5961da177e4SLinus Torvalds 5971da177e4SLinus Torvalds return e; 5981da177e4SLinus Torvalds } 5991da177e4SLinus Torvalds 6003510cb94SJon Brassow static void free_completed_exception(struct dm_exception *e) 6011da177e4SLinus Torvalds { 6021da177e4SLinus Torvalds kmem_cache_free(exception_cache, e); 6031da177e4SLinus Torvalds } 6041da177e4SLinus Torvalds 60592e86812SMikulas Patocka static struct dm_snap_pending_exception *alloc_pending_exception(struct dm_snapshot *s) 6061da177e4SLinus Torvalds { 60792e86812SMikulas Patocka struct dm_snap_pending_exception *pe = mempool_alloc(s->pending_pool, 60892e86812SMikulas Patocka GFP_NOIO); 60992e86812SMikulas Patocka 610879129d2SMikulas Patocka atomic_inc(&s->pending_exceptions_count); 61192e86812SMikulas Patocka pe->snap = s; 61292e86812SMikulas Patocka 61392e86812SMikulas Patocka return pe; 6141da177e4SLinus Torvalds } 6151da177e4SLinus Torvalds 616028867acSAlasdair G Kergon static void free_pending_exception(struct dm_snap_pending_exception *pe) 6171da177e4SLinus Torvalds { 618879129d2SMikulas Patocka struct dm_snapshot *s = pe->snap; 619879129d2SMikulas Patocka 620879129d2SMikulas Patocka mempool_free(pe, s->pending_pool); 621879129d2SMikulas Patocka smp_mb__before_atomic_dec(); 622879129d2SMikulas Patocka atomic_dec(&s->pending_exceptions_count); 6231da177e4SLinus Torvalds } 6241da177e4SLinus Torvalds 6253510cb94SJon Brassow static void dm_insert_exception(struct dm_exception_table *eh, 6261d4989c8SJon Brassow struct dm_exception *new_e) 627d74f81f8SMilan Broz { 628d74f81f8SMilan Broz struct list_head *l; 6291d4989c8SJon Brassow struct dm_exception *e = NULL; 630d74f81f8SMilan Broz 631d74f81f8SMilan Broz l = &eh->table[exception_hash(eh, new_e->old_chunk)]; 632d74f81f8SMilan Broz 633d74f81f8SMilan Broz /* Add immediately if this table doesn't support consecutive chunks */ 634d74f81f8SMilan Broz if (!eh->hash_shift) 635d74f81f8SMilan Broz goto out; 636d74f81f8SMilan Broz 637d74f81f8SMilan Broz /* List is ordered by old_chunk */ 638d74f81f8SMilan Broz list_for_each_entry_reverse(e, l, hash_list) { 639d74f81f8SMilan Broz /* Insert after an existing chunk? */ 640d74f81f8SMilan Broz if (new_e->old_chunk == (e->old_chunk + 641d74f81f8SMilan Broz dm_consecutive_chunk_count(e) + 1) && 642d74f81f8SMilan Broz new_e->new_chunk == (dm_chunk_number(e->new_chunk) + 643d74f81f8SMilan Broz dm_consecutive_chunk_count(e) + 1)) { 644d74f81f8SMilan Broz dm_consecutive_chunk_count_inc(e); 6453510cb94SJon Brassow free_completed_exception(new_e); 646d74f81f8SMilan Broz return; 647d74f81f8SMilan Broz } 648d74f81f8SMilan Broz 649d74f81f8SMilan Broz /* Insert before an existing chunk? */ 650d74f81f8SMilan Broz if (new_e->old_chunk == (e->old_chunk - 1) && 651d74f81f8SMilan Broz new_e->new_chunk == (dm_chunk_number(e->new_chunk) - 1)) { 652d74f81f8SMilan Broz dm_consecutive_chunk_count_inc(e); 653d74f81f8SMilan Broz e->old_chunk--; 654d74f81f8SMilan Broz e->new_chunk--; 6553510cb94SJon Brassow free_completed_exception(new_e); 656d74f81f8SMilan Broz return; 657d74f81f8SMilan Broz } 658d74f81f8SMilan Broz 659d74f81f8SMilan Broz if (new_e->old_chunk > e->old_chunk) 660d74f81f8SMilan Broz break; 661d74f81f8SMilan Broz } 662d74f81f8SMilan Broz 663d74f81f8SMilan Broz out: 664d74f81f8SMilan Broz list_add(&new_e->hash_list, e ? &e->hash_list : l); 665d74f81f8SMilan Broz } 666d74f81f8SMilan Broz 667a159c1acSJonathan Brassow /* 668a159c1acSJonathan Brassow * Callback used by the exception stores to load exceptions when 669a159c1acSJonathan Brassow * initialising. 670a159c1acSJonathan Brassow */ 671a159c1acSJonathan Brassow static int dm_add_exception(void *context, chunk_t old, chunk_t new) 6721da177e4SLinus Torvalds { 673a159c1acSJonathan Brassow struct dm_snapshot *s = context; 6741d4989c8SJon Brassow struct dm_exception *e; 6751da177e4SLinus Torvalds 6763510cb94SJon Brassow e = alloc_completed_exception(); 6771da177e4SLinus Torvalds if (!e) 6781da177e4SLinus Torvalds return -ENOMEM; 6791da177e4SLinus Torvalds 6801da177e4SLinus Torvalds e->old_chunk = old; 681d74f81f8SMilan Broz 682d74f81f8SMilan Broz /* Consecutive_count is implicitly initialised to zero */ 6831da177e4SLinus Torvalds e->new_chunk = new; 684d74f81f8SMilan Broz 6853510cb94SJon Brassow dm_insert_exception(&s->complete, e); 686d74f81f8SMilan Broz 6871da177e4SLinus Torvalds return 0; 6881da177e4SLinus Torvalds } 6891da177e4SLinus Torvalds 6907e201b35SMikulas Patocka /* 6917e201b35SMikulas Patocka * Return a minimum chunk size of all snapshots that have the specified origin. 6927e201b35SMikulas Patocka * Return zero if the origin has no snapshots. 6937e201b35SMikulas Patocka */ 694542f9038SMike Snitzer static uint32_t __minimum_chunk_size(struct origin *o) 6957e201b35SMikulas Patocka { 6967e201b35SMikulas Patocka struct dm_snapshot *snap; 6977e201b35SMikulas Patocka unsigned chunk_size = 0; 6987e201b35SMikulas Patocka 6997e201b35SMikulas Patocka if (o) 7007e201b35SMikulas Patocka list_for_each_entry(snap, &o->snapshots, list) 7017e201b35SMikulas Patocka chunk_size = min_not_zero(chunk_size, 7027e201b35SMikulas Patocka snap->store->chunk_size); 7037e201b35SMikulas Patocka 704542f9038SMike Snitzer return (uint32_t) chunk_size; 7057e201b35SMikulas Patocka } 7067e201b35SMikulas Patocka 7071da177e4SLinus Torvalds /* 7081da177e4SLinus Torvalds * Hard coded magic. 7091da177e4SLinus Torvalds */ 7101da177e4SLinus Torvalds static int calc_max_buckets(void) 7111da177e4SLinus Torvalds { 7121da177e4SLinus Torvalds /* use a fixed size of 2MB */ 7131da177e4SLinus Torvalds unsigned long mem = 2 * 1024 * 1024; 7141da177e4SLinus Torvalds mem /= sizeof(struct list_head); 7151da177e4SLinus Torvalds 7161da177e4SLinus Torvalds return mem; 7171da177e4SLinus Torvalds } 7181da177e4SLinus Torvalds 7191da177e4SLinus Torvalds /* 7201da177e4SLinus Torvalds * Allocate room for a suitable hash table. 7211da177e4SLinus Torvalds */ 722fee1998eSJonathan Brassow static int init_hash_tables(struct dm_snapshot *s) 7231da177e4SLinus Torvalds { 7241da177e4SLinus Torvalds sector_t hash_size, cow_dev_size, origin_dev_size, max_buckets; 7251da177e4SLinus Torvalds 7261da177e4SLinus Torvalds /* 7271da177e4SLinus Torvalds * Calculate based on the size of the original volume or 7281da177e4SLinus Torvalds * the COW volume... 7291da177e4SLinus Torvalds */ 730fc56f6fbSMike Snitzer cow_dev_size = get_dev_size(s->cow->bdev); 7311da177e4SLinus Torvalds origin_dev_size = get_dev_size(s->origin->bdev); 7321da177e4SLinus Torvalds max_buckets = calc_max_buckets(); 7331da177e4SLinus Torvalds 734fee1998eSJonathan Brassow hash_size = min(origin_dev_size, cow_dev_size) >> s->store->chunk_shift; 7351da177e4SLinus Torvalds hash_size = min(hash_size, max_buckets); 7361da177e4SLinus Torvalds 7378e87b9b8SMikulas Patocka if (hash_size < 64) 7388e87b9b8SMikulas Patocka hash_size = 64; 7398defd830SRobert P. J. Day hash_size = rounddown_pow_of_two(hash_size); 7403510cb94SJon Brassow if (dm_exception_table_init(&s->complete, hash_size, 741d74f81f8SMilan Broz DM_CHUNK_CONSECUTIVE_BITS)) 7421da177e4SLinus Torvalds return -ENOMEM; 7431da177e4SLinus Torvalds 7441da177e4SLinus Torvalds /* 7451da177e4SLinus Torvalds * Allocate hash table for in-flight exceptions 7461da177e4SLinus Torvalds * Make this smaller than the real hash table 7471da177e4SLinus Torvalds */ 7481da177e4SLinus Torvalds hash_size >>= 3; 7491da177e4SLinus Torvalds if (hash_size < 64) 7501da177e4SLinus Torvalds hash_size = 64; 7511da177e4SLinus Torvalds 7523510cb94SJon Brassow if (dm_exception_table_init(&s->pending, hash_size, 0)) { 7533510cb94SJon Brassow dm_exception_table_exit(&s->complete, exception_cache); 7541da177e4SLinus Torvalds return -ENOMEM; 7551da177e4SLinus Torvalds } 7561da177e4SLinus Torvalds 7571da177e4SLinus Torvalds return 0; 7581da177e4SLinus Torvalds } 7591da177e4SLinus Torvalds 7601e03f97eSMikulas Patocka static void merge_shutdown(struct dm_snapshot *s) 7611e03f97eSMikulas Patocka { 7621e03f97eSMikulas Patocka clear_bit_unlock(RUNNING_MERGE, &s->state_bits); 7631e03f97eSMikulas Patocka smp_mb__after_clear_bit(); 7641e03f97eSMikulas Patocka wake_up_bit(&s->state_bits, RUNNING_MERGE); 7651e03f97eSMikulas Patocka } 7661e03f97eSMikulas Patocka 7679fe86254SMikulas Patocka static struct bio *__release_queued_bios_after_merge(struct dm_snapshot *s) 7689fe86254SMikulas Patocka { 7699fe86254SMikulas Patocka s->first_merging_chunk = 0; 7709fe86254SMikulas Patocka s->num_merging_chunks = 0; 7719fe86254SMikulas Patocka 7729fe86254SMikulas Patocka return bio_list_get(&s->bios_queued_during_merge); 7739fe86254SMikulas Patocka } 7749fe86254SMikulas Patocka 7751e03f97eSMikulas Patocka /* 7761e03f97eSMikulas Patocka * Remove one chunk from the index of completed exceptions. 7771e03f97eSMikulas Patocka */ 7781e03f97eSMikulas Patocka static int __remove_single_exception_chunk(struct dm_snapshot *s, 7791e03f97eSMikulas Patocka chunk_t old_chunk) 7801e03f97eSMikulas Patocka { 7811e03f97eSMikulas Patocka struct dm_exception *e; 7821e03f97eSMikulas Patocka 7831e03f97eSMikulas Patocka e = dm_lookup_exception(&s->complete, old_chunk); 7841e03f97eSMikulas Patocka if (!e) { 7851e03f97eSMikulas Patocka DMERR("Corruption detected: exception for block %llu is " 7861e03f97eSMikulas Patocka "on disk but not in memory", 7871e03f97eSMikulas Patocka (unsigned long long)old_chunk); 7881e03f97eSMikulas Patocka return -EINVAL; 7891e03f97eSMikulas Patocka } 7901e03f97eSMikulas Patocka 7911e03f97eSMikulas Patocka /* 7921e03f97eSMikulas Patocka * If this is the only chunk using this exception, remove exception. 7931e03f97eSMikulas Patocka */ 7941e03f97eSMikulas Patocka if (!dm_consecutive_chunk_count(e)) { 7951e03f97eSMikulas Patocka dm_remove_exception(e); 7961e03f97eSMikulas Patocka free_completed_exception(e); 7971e03f97eSMikulas Patocka return 0; 7981e03f97eSMikulas Patocka } 7991e03f97eSMikulas Patocka 8001e03f97eSMikulas Patocka /* 8011e03f97eSMikulas Patocka * The chunk may be either at the beginning or the end of a 8021e03f97eSMikulas Patocka * group of consecutive chunks - never in the middle. We are 8031e03f97eSMikulas Patocka * removing chunks in the opposite order to that in which they 8041e03f97eSMikulas Patocka * were added, so this should always be true. 8051e03f97eSMikulas Patocka * Decrement the consecutive chunk counter and adjust the 8061e03f97eSMikulas Patocka * starting point if necessary. 8071e03f97eSMikulas Patocka */ 8081e03f97eSMikulas Patocka if (old_chunk == e->old_chunk) { 8091e03f97eSMikulas Patocka e->old_chunk++; 8101e03f97eSMikulas Patocka e->new_chunk++; 8111e03f97eSMikulas Patocka } else if (old_chunk != e->old_chunk + 8121e03f97eSMikulas Patocka dm_consecutive_chunk_count(e)) { 8131e03f97eSMikulas Patocka DMERR("Attempt to merge block %llu from the " 8141e03f97eSMikulas Patocka "middle of a chunk range [%llu - %llu]", 8151e03f97eSMikulas Patocka (unsigned long long)old_chunk, 8161e03f97eSMikulas Patocka (unsigned long long)e->old_chunk, 8171e03f97eSMikulas Patocka (unsigned long long) 8181e03f97eSMikulas Patocka e->old_chunk + dm_consecutive_chunk_count(e)); 8191e03f97eSMikulas Patocka return -EINVAL; 8201e03f97eSMikulas Patocka } 8211e03f97eSMikulas Patocka 8221e03f97eSMikulas Patocka dm_consecutive_chunk_count_dec(e); 8231e03f97eSMikulas Patocka 8241e03f97eSMikulas Patocka return 0; 8251e03f97eSMikulas Patocka } 8261e03f97eSMikulas Patocka 8279fe86254SMikulas Patocka static void flush_bios(struct bio *bio); 8289fe86254SMikulas Patocka 8299fe86254SMikulas Patocka static int remove_single_exception_chunk(struct dm_snapshot *s) 8301e03f97eSMikulas Patocka { 8319fe86254SMikulas Patocka struct bio *b = NULL; 8329fe86254SMikulas Patocka int r; 8339fe86254SMikulas Patocka chunk_t old_chunk = s->first_merging_chunk + s->num_merging_chunks - 1; 8341e03f97eSMikulas Patocka 8351e03f97eSMikulas Patocka down_write(&s->lock); 8369fe86254SMikulas Patocka 8379fe86254SMikulas Patocka /* 8389fe86254SMikulas Patocka * Process chunks (and associated exceptions) in reverse order 8399fe86254SMikulas Patocka * so that dm_consecutive_chunk_count_dec() accounting works. 8409fe86254SMikulas Patocka */ 8419fe86254SMikulas Patocka do { 8421e03f97eSMikulas Patocka r = __remove_single_exception_chunk(s, old_chunk); 8439fe86254SMikulas Patocka if (r) 8449fe86254SMikulas Patocka goto out; 8459fe86254SMikulas Patocka } while (old_chunk-- > s->first_merging_chunk); 8469fe86254SMikulas Patocka 8479fe86254SMikulas Patocka b = __release_queued_bios_after_merge(s); 8489fe86254SMikulas Patocka 8499fe86254SMikulas Patocka out: 8501e03f97eSMikulas Patocka up_write(&s->lock); 8519fe86254SMikulas Patocka if (b) 8529fe86254SMikulas Patocka flush_bios(b); 8531e03f97eSMikulas Patocka 8541e03f97eSMikulas Patocka return r; 8551e03f97eSMikulas Patocka } 8561e03f97eSMikulas Patocka 85773dfd078SMikulas Patocka static int origin_write_extent(struct dm_snapshot *merging_snap, 85873dfd078SMikulas Patocka sector_t sector, unsigned chunk_size); 85973dfd078SMikulas Patocka 8601e03f97eSMikulas Patocka static void merge_callback(int read_err, unsigned long write_err, 8611e03f97eSMikulas Patocka void *context); 8621e03f97eSMikulas Patocka 86373dfd078SMikulas Patocka static uint64_t read_pending_exceptions_done_count(void) 86473dfd078SMikulas Patocka { 86573dfd078SMikulas Patocka uint64_t pending_exceptions_done; 86673dfd078SMikulas Patocka 86773dfd078SMikulas Patocka spin_lock(&_pending_exceptions_done_spinlock); 86873dfd078SMikulas Patocka pending_exceptions_done = _pending_exceptions_done_count; 86973dfd078SMikulas Patocka spin_unlock(&_pending_exceptions_done_spinlock); 87073dfd078SMikulas Patocka 87173dfd078SMikulas Patocka return pending_exceptions_done; 87273dfd078SMikulas Patocka } 87373dfd078SMikulas Patocka 87473dfd078SMikulas Patocka static void increment_pending_exceptions_done_count(void) 87573dfd078SMikulas Patocka { 87673dfd078SMikulas Patocka spin_lock(&_pending_exceptions_done_spinlock); 87773dfd078SMikulas Patocka _pending_exceptions_done_count++; 87873dfd078SMikulas Patocka spin_unlock(&_pending_exceptions_done_spinlock); 87973dfd078SMikulas Patocka 88073dfd078SMikulas Patocka wake_up_all(&_pending_exceptions_done); 88173dfd078SMikulas Patocka } 88273dfd078SMikulas Patocka 8831e03f97eSMikulas Patocka static void snapshot_merge_next_chunks(struct dm_snapshot *s) 8841e03f97eSMikulas Patocka { 8858a2d5286SMike Snitzer int i, linear_chunks; 8861e03f97eSMikulas Patocka chunk_t old_chunk, new_chunk; 8871e03f97eSMikulas Patocka struct dm_io_region src, dest; 8888a2d5286SMike Snitzer sector_t io_size; 88973dfd078SMikulas Patocka uint64_t previous_count; 8901e03f97eSMikulas Patocka 8911e03f97eSMikulas Patocka BUG_ON(!test_bit(RUNNING_MERGE, &s->state_bits)); 8921e03f97eSMikulas Patocka if (unlikely(test_bit(SHUTDOWN_MERGE, &s->state_bits))) 8931e03f97eSMikulas Patocka goto shut; 8941e03f97eSMikulas Patocka 8951e03f97eSMikulas Patocka /* 8961e03f97eSMikulas Patocka * valid flag never changes during merge, so no lock required. 8971e03f97eSMikulas Patocka */ 8981e03f97eSMikulas Patocka if (!s->valid) { 8991e03f97eSMikulas Patocka DMERR("Snapshot is invalid: can't merge"); 9001e03f97eSMikulas Patocka goto shut; 9011e03f97eSMikulas Patocka } 9021e03f97eSMikulas Patocka 9038a2d5286SMike Snitzer linear_chunks = s->store->type->prepare_merge(s->store, &old_chunk, 9048a2d5286SMike Snitzer &new_chunk); 9058a2d5286SMike Snitzer if (linear_chunks <= 0) { 906d8ddb1cfSMike Snitzer if (linear_chunks < 0) { 9071e03f97eSMikulas Patocka DMERR("Read error in exception store: " 9081e03f97eSMikulas Patocka "shutting down merge"); 909d8ddb1cfSMike Snitzer down_write(&s->lock); 910d8ddb1cfSMike Snitzer s->merge_failed = 1; 911d8ddb1cfSMike Snitzer up_write(&s->lock); 912d8ddb1cfSMike Snitzer } 9131e03f97eSMikulas Patocka goto shut; 9141e03f97eSMikulas Patocka } 9151e03f97eSMikulas Patocka 9168a2d5286SMike Snitzer /* Adjust old_chunk and new_chunk to reflect start of linear region */ 9178a2d5286SMike Snitzer old_chunk = old_chunk + 1 - linear_chunks; 9188a2d5286SMike Snitzer new_chunk = new_chunk + 1 - linear_chunks; 9198a2d5286SMike Snitzer 9208a2d5286SMike Snitzer /* 9218a2d5286SMike Snitzer * Use one (potentially large) I/O to copy all 'linear_chunks' 9228a2d5286SMike Snitzer * from the exception store to the origin 9238a2d5286SMike Snitzer */ 9248a2d5286SMike Snitzer io_size = linear_chunks * s->store->chunk_size; 9251e03f97eSMikulas Patocka 9261e03f97eSMikulas Patocka dest.bdev = s->origin->bdev; 9271e03f97eSMikulas Patocka dest.sector = chunk_to_sector(s->store, old_chunk); 9288a2d5286SMike Snitzer dest.count = min(io_size, get_dev_size(dest.bdev) - dest.sector); 9291e03f97eSMikulas Patocka 9301e03f97eSMikulas Patocka src.bdev = s->cow->bdev; 9311e03f97eSMikulas Patocka src.sector = chunk_to_sector(s->store, new_chunk); 9321e03f97eSMikulas Patocka src.count = dest.count; 9331e03f97eSMikulas Patocka 93473dfd078SMikulas Patocka /* 93573dfd078SMikulas Patocka * Reallocate any exceptions needed in other snapshots then 93673dfd078SMikulas Patocka * wait for the pending exceptions to complete. 93773dfd078SMikulas Patocka * Each time any pending exception (globally on the system) 93873dfd078SMikulas Patocka * completes we are woken and repeat the process to find out 93973dfd078SMikulas Patocka * if we can proceed. While this may not seem a particularly 94073dfd078SMikulas Patocka * efficient algorithm, it is not expected to have any 94173dfd078SMikulas Patocka * significant impact on performance. 94273dfd078SMikulas Patocka */ 94373dfd078SMikulas Patocka previous_count = read_pending_exceptions_done_count(); 9448a2d5286SMike Snitzer while (origin_write_extent(s, dest.sector, io_size)) { 94573dfd078SMikulas Patocka wait_event(_pending_exceptions_done, 94673dfd078SMikulas Patocka (read_pending_exceptions_done_count() != 94773dfd078SMikulas Patocka previous_count)); 94873dfd078SMikulas Patocka /* Retry after the wait, until all exceptions are done. */ 94973dfd078SMikulas Patocka previous_count = read_pending_exceptions_done_count(); 95073dfd078SMikulas Patocka } 95173dfd078SMikulas Patocka 9529fe86254SMikulas Patocka down_write(&s->lock); 9539fe86254SMikulas Patocka s->first_merging_chunk = old_chunk; 9548a2d5286SMike Snitzer s->num_merging_chunks = linear_chunks; 9559fe86254SMikulas Patocka up_write(&s->lock); 9569fe86254SMikulas Patocka 9578a2d5286SMike Snitzer /* Wait until writes to all 'linear_chunks' drain */ 9588a2d5286SMike Snitzer for (i = 0; i < linear_chunks; i++) 9598a2d5286SMike Snitzer __check_for_conflicting_io(s, old_chunk + i); 9609fe86254SMikulas Patocka 9611e03f97eSMikulas Patocka dm_kcopyd_copy(s->kcopyd_client, &src, 1, &dest, 0, merge_callback, s); 9621e03f97eSMikulas Patocka return; 9631e03f97eSMikulas Patocka 9641e03f97eSMikulas Patocka shut: 9651e03f97eSMikulas Patocka merge_shutdown(s); 9661e03f97eSMikulas Patocka } 9671e03f97eSMikulas Patocka 9689fe86254SMikulas Patocka static void error_bios(struct bio *bio); 9699fe86254SMikulas Patocka 9701e03f97eSMikulas Patocka static void merge_callback(int read_err, unsigned long write_err, void *context) 9711e03f97eSMikulas Patocka { 9721e03f97eSMikulas Patocka struct dm_snapshot *s = context; 9739fe86254SMikulas Patocka struct bio *b = NULL; 9741e03f97eSMikulas Patocka 9751e03f97eSMikulas Patocka if (read_err || write_err) { 9761e03f97eSMikulas Patocka if (read_err) 9771e03f97eSMikulas Patocka DMERR("Read error: shutting down merge."); 9781e03f97eSMikulas Patocka else 9791e03f97eSMikulas Patocka DMERR("Write error: shutting down merge."); 9801e03f97eSMikulas Patocka goto shut; 9811e03f97eSMikulas Patocka } 9821e03f97eSMikulas Patocka 9839fe86254SMikulas Patocka if (s->store->type->commit_merge(s->store, 9849fe86254SMikulas Patocka s->num_merging_chunks) < 0) { 9851e03f97eSMikulas Patocka DMERR("Write error in exception store: shutting down merge"); 9861e03f97eSMikulas Patocka goto shut; 9871e03f97eSMikulas Patocka } 9881e03f97eSMikulas Patocka 9899fe86254SMikulas Patocka if (remove_single_exception_chunk(s) < 0) 9909fe86254SMikulas Patocka goto shut; 9919fe86254SMikulas Patocka 9921e03f97eSMikulas Patocka snapshot_merge_next_chunks(s); 9931e03f97eSMikulas Patocka 9941e03f97eSMikulas Patocka return; 9951e03f97eSMikulas Patocka 9961e03f97eSMikulas Patocka shut: 9979fe86254SMikulas Patocka down_write(&s->lock); 998d8ddb1cfSMike Snitzer s->merge_failed = 1; 9999fe86254SMikulas Patocka b = __release_queued_bios_after_merge(s); 10009fe86254SMikulas Patocka up_write(&s->lock); 10019fe86254SMikulas Patocka error_bios(b); 10029fe86254SMikulas Patocka 10031e03f97eSMikulas Patocka merge_shutdown(s); 10041e03f97eSMikulas Patocka } 10051e03f97eSMikulas Patocka 10061e03f97eSMikulas Patocka static void start_merge(struct dm_snapshot *s) 10071e03f97eSMikulas Patocka { 10081e03f97eSMikulas Patocka if (!test_and_set_bit(RUNNING_MERGE, &s->state_bits)) 10091e03f97eSMikulas Patocka snapshot_merge_next_chunks(s); 10101e03f97eSMikulas Patocka } 10111e03f97eSMikulas Patocka 10121e03f97eSMikulas Patocka static int wait_schedule(void *ptr) 10131e03f97eSMikulas Patocka { 10141e03f97eSMikulas Patocka schedule(); 10151e03f97eSMikulas Patocka 10161e03f97eSMikulas Patocka return 0; 10171e03f97eSMikulas Patocka } 10181e03f97eSMikulas Patocka 10191e03f97eSMikulas Patocka /* 10201e03f97eSMikulas Patocka * Stop the merging process and wait until it finishes. 10211e03f97eSMikulas Patocka */ 10221e03f97eSMikulas Patocka static void stop_merge(struct dm_snapshot *s) 10231e03f97eSMikulas Patocka { 10241e03f97eSMikulas Patocka set_bit(SHUTDOWN_MERGE, &s->state_bits); 10251e03f97eSMikulas Patocka wait_on_bit(&s->state_bits, RUNNING_MERGE, wait_schedule, 10261e03f97eSMikulas Patocka TASK_UNINTERRUPTIBLE); 10271e03f97eSMikulas Patocka clear_bit(SHUTDOWN_MERGE, &s->state_bits); 10281e03f97eSMikulas Patocka } 10291e03f97eSMikulas Patocka 10301da177e4SLinus Torvalds /* 10311da177e4SLinus Torvalds * Construct a snapshot mapping: <origin_dev> <COW-dev> <p/n> <chunk-size> 10321da177e4SLinus Torvalds */ 10331da177e4SLinus Torvalds static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv) 10341da177e4SLinus Torvalds { 10351da177e4SLinus Torvalds struct dm_snapshot *s; 1036cd45daffSMikulas Patocka int i; 10371da177e4SLinus Torvalds int r = -EINVAL; 1038fc56f6fbSMike Snitzer char *origin_path, *cow_path; 103910b8106aSMike Snitzer unsigned args_used, num_flush_requests = 1; 104010b8106aSMike Snitzer fmode_t origin_mode = FMODE_READ; 10411da177e4SLinus Torvalds 10424c7e3bf4SMark McLoughlin if (argc != 4) { 104372d94861SAlasdair G Kergon ti->error = "requires exactly 4 arguments"; 10441da177e4SLinus Torvalds r = -EINVAL; 1045fc56f6fbSMike Snitzer goto bad; 10461da177e4SLinus Torvalds } 10471da177e4SLinus Torvalds 104810b8106aSMike Snitzer if (dm_target_is_snapshot_merge(ti)) { 104910b8106aSMike Snitzer num_flush_requests = 2; 105010b8106aSMike Snitzer origin_mode = FMODE_WRITE; 105110b8106aSMike Snitzer } 105210b8106aSMike Snitzer 10531da177e4SLinus Torvalds s = kmalloc(sizeof(*s), GFP_KERNEL); 1054fee1998eSJonathan Brassow if (!s) { 1055a2d2b034SJonathan Brassow ti->error = "Cannot allocate private snapshot structure"; 10561da177e4SLinus Torvalds r = -ENOMEM; 1057fc56f6fbSMike Snitzer goto bad; 10581da177e4SLinus Torvalds } 10591da177e4SLinus Torvalds 1060c2411045SMikulas Patocka origin_path = argv[0]; 1061c2411045SMikulas Patocka argv++; 1062c2411045SMikulas Patocka argc--; 1063c2411045SMikulas Patocka 1064c2411045SMikulas Patocka r = dm_get_device(ti, origin_path, origin_mode, &s->origin); 1065c2411045SMikulas Patocka if (r) { 1066c2411045SMikulas Patocka ti->error = "Cannot get origin device"; 1067c2411045SMikulas Patocka goto bad_origin; 1068c2411045SMikulas Patocka } 1069c2411045SMikulas Patocka 1070fc56f6fbSMike Snitzer cow_path = argv[0]; 1071fc56f6fbSMike Snitzer argv++; 1072fc56f6fbSMike Snitzer argc--; 1073fc56f6fbSMike Snitzer 1074024d37e9SMilan Broz r = dm_get_device(ti, cow_path, dm_table_get_mode(ti->table), &s->cow); 1075fc56f6fbSMike Snitzer if (r) { 1076fc56f6fbSMike Snitzer ti->error = "Cannot get COW device"; 1077fc56f6fbSMike Snitzer goto bad_cow; 1078fc56f6fbSMike Snitzer } 1079fc56f6fbSMike Snitzer 1080fc56f6fbSMike Snitzer r = dm_exception_store_create(ti, argc, argv, s, &args_used, &s->store); 1081fc56f6fbSMike Snitzer if (r) { 1082fc56f6fbSMike Snitzer ti->error = "Couldn't create exception store"; 1083fc56f6fbSMike Snitzer r = -EINVAL; 1084fc56f6fbSMike Snitzer goto bad_store; 1085fc56f6fbSMike Snitzer } 1086fc56f6fbSMike Snitzer 1087fc56f6fbSMike Snitzer argv += args_used; 1088fc56f6fbSMike Snitzer argc -= args_used; 1089fc56f6fbSMike Snitzer 1090fc56f6fbSMike Snitzer s->ti = ti; 10911da177e4SLinus Torvalds s->valid = 1; 1092aa14edebSAlasdair G Kergon s->active = 0; 1093879129d2SMikulas Patocka atomic_set(&s->pending_exceptions_count, 0); 10941da177e4SLinus Torvalds init_rwsem(&s->lock); 1095c1f0c183SMike Snitzer INIT_LIST_HEAD(&s->list); 1096ca3a931fSAlasdair G Kergon spin_lock_init(&s->pe_lock); 10971e03f97eSMikulas Patocka s->state_bits = 0; 1098d8ddb1cfSMike Snitzer s->merge_failed = 0; 10999fe86254SMikulas Patocka s->first_merging_chunk = 0; 11009fe86254SMikulas Patocka s->num_merging_chunks = 0; 11019fe86254SMikulas Patocka bio_list_init(&s->bios_queued_during_merge); 11021da177e4SLinus Torvalds 11031da177e4SLinus Torvalds /* Allocate hash table for COW data */ 1104fee1998eSJonathan Brassow if (init_hash_tables(s)) { 11051da177e4SLinus Torvalds ti->error = "Unable to allocate hash table space"; 11061da177e4SLinus Torvalds r = -ENOMEM; 1107fee1998eSJonathan Brassow goto bad_hash_tables; 11081da177e4SLinus Torvalds } 11091da177e4SLinus Torvalds 1110fa34ce73SMikulas Patocka s->kcopyd_client = dm_kcopyd_client_create(); 1111fa34ce73SMikulas Patocka if (IS_ERR(s->kcopyd_client)) { 1112fa34ce73SMikulas Patocka r = PTR_ERR(s->kcopyd_client); 11131da177e4SLinus Torvalds ti->error = "Could not create kcopyd client"; 1114fee1998eSJonathan Brassow goto bad_kcopyd; 11151da177e4SLinus Torvalds } 11161da177e4SLinus Torvalds 111792e86812SMikulas Patocka s->pending_pool = mempool_create_slab_pool(MIN_IOS, pending_cache); 111892e86812SMikulas Patocka if (!s->pending_pool) { 111992e86812SMikulas Patocka ti->error = "Could not allocate mempool for pending exceptions"; 1120fee1998eSJonathan Brassow goto bad_pending_pool; 112192e86812SMikulas Patocka } 112292e86812SMikulas Patocka 1123cd45daffSMikulas Patocka s->tracked_chunk_pool = mempool_create_slab_pool(MIN_IOS, 1124cd45daffSMikulas Patocka tracked_chunk_cache); 1125cd45daffSMikulas Patocka if (!s->tracked_chunk_pool) { 1126cd45daffSMikulas Patocka ti->error = "Could not allocate tracked_chunk mempool for " 1127cd45daffSMikulas Patocka "tracking reads"; 112892e86812SMikulas Patocka goto bad_tracked_chunk_pool; 1129cd45daffSMikulas Patocka } 1130cd45daffSMikulas Patocka 1131cd45daffSMikulas Patocka for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) 1132cd45daffSMikulas Patocka INIT_HLIST_HEAD(&s->tracked_chunk_hash[i]); 1133cd45daffSMikulas Patocka 1134cd45daffSMikulas Patocka spin_lock_init(&s->tracked_chunk_lock); 1135cd45daffSMikulas Patocka 1136c1f0c183SMike Snitzer ti->private = s; 113710b8106aSMike Snitzer ti->num_flush_requests = num_flush_requests; 1138c1f0c183SMike Snitzer 1139c1f0c183SMike Snitzer /* Add snapshot to the list of snapshots for this origin */ 1140c1f0c183SMike Snitzer /* Exceptions aren't triggered till snapshot_resume() is called */ 1141c1f0c183SMike Snitzer r = register_snapshot(s); 1142c1f0c183SMike Snitzer if (r == -ENOMEM) { 1143c1f0c183SMike Snitzer ti->error = "Snapshot origin struct allocation failed"; 1144c1f0c183SMike Snitzer goto bad_load_and_register; 1145c1f0c183SMike Snitzer } else if (r < 0) { 1146c1f0c183SMike Snitzer /* invalid handover, register_snapshot has set ti->error */ 1147c1f0c183SMike Snitzer goto bad_load_and_register; 1148c1f0c183SMike Snitzer } 1149c1f0c183SMike Snitzer 1150c1f0c183SMike Snitzer /* 1151c1f0c183SMike Snitzer * Metadata must only be loaded into one table at once, so skip this 1152c1f0c183SMike Snitzer * if metadata will be handed over during resume. 1153c1f0c183SMike Snitzer * Chunk size will be set during the handover - set it to zero to 1154c1f0c183SMike Snitzer * ensure it's ignored. 1155c1f0c183SMike Snitzer */ 1156c1f0c183SMike Snitzer if (r > 0) { 1157c1f0c183SMike Snitzer s->store->chunk_size = 0; 1158c1f0c183SMike Snitzer return 0; 1159c1f0c183SMike Snitzer } 1160c1f0c183SMike Snitzer 1161493df71cSJonathan Brassow r = s->store->type->read_metadata(s->store, dm_add_exception, 1162493df71cSJonathan Brassow (void *)s); 11630764147bSMilan Broz if (r < 0) { 1164f9cea4f7SMark McLoughlin ti->error = "Failed to read snapshot metadata"; 1165c1f0c183SMike Snitzer goto bad_read_metadata; 11660764147bSMilan Broz } else if (r > 0) { 11670764147bSMilan Broz s->valid = 0; 11680764147bSMilan Broz DMWARN("Snapshot is marked invalid."); 1169f9cea4f7SMark McLoughlin } 1170aa14edebSAlasdair G Kergon 11713f2412dcSMikulas Patocka if (!s->store->chunk_size) { 11723f2412dcSMikulas Patocka ti->error = "Chunk size not set"; 1173c1f0c183SMike Snitzer goto bad_read_metadata; 11743f2412dcSMikulas Patocka } 1175542f9038SMike Snitzer 1176542f9038SMike Snitzer r = dm_set_target_max_io_len(ti, s->store->chunk_size); 1177542f9038SMike Snitzer if (r) 1178542f9038SMike Snitzer goto bad_read_metadata; 11791da177e4SLinus Torvalds 11801da177e4SLinus Torvalds return 0; 11811da177e4SLinus Torvalds 1182c1f0c183SMike Snitzer bad_read_metadata: 1183c1f0c183SMike Snitzer unregister_snapshot(s); 1184c1f0c183SMike Snitzer 1185cd45daffSMikulas Patocka bad_load_and_register: 1186cd45daffSMikulas Patocka mempool_destroy(s->tracked_chunk_pool); 1187cd45daffSMikulas Patocka 118892e86812SMikulas Patocka bad_tracked_chunk_pool: 118992e86812SMikulas Patocka mempool_destroy(s->pending_pool); 119092e86812SMikulas Patocka 1191fee1998eSJonathan Brassow bad_pending_pool: 1192eb69aca5SHeinz Mauelshagen dm_kcopyd_client_destroy(s->kcopyd_client); 11931da177e4SLinus Torvalds 1194fee1998eSJonathan Brassow bad_kcopyd: 11953510cb94SJon Brassow dm_exception_table_exit(&s->pending, pending_cache); 11963510cb94SJon Brassow dm_exception_table_exit(&s->complete, exception_cache); 11971da177e4SLinus Torvalds 1198fee1998eSJonathan Brassow bad_hash_tables: 1199fc56f6fbSMike Snitzer dm_exception_store_destroy(s->store); 1200fc56f6fbSMike Snitzer 1201fc56f6fbSMike Snitzer bad_store: 1202fc56f6fbSMike Snitzer dm_put_device(ti, s->cow); 1203fc56f6fbSMike Snitzer 1204fc56f6fbSMike Snitzer bad_cow: 1205c2411045SMikulas Patocka dm_put_device(ti, s->origin); 1206c2411045SMikulas Patocka 1207c2411045SMikulas Patocka bad_origin: 12081da177e4SLinus Torvalds kfree(s); 12091da177e4SLinus Torvalds 1210fc56f6fbSMike Snitzer bad: 12111da177e4SLinus Torvalds return r; 12121da177e4SLinus Torvalds } 12131da177e4SLinus Torvalds 121431c93a0cSMilan Broz static void __free_exceptions(struct dm_snapshot *s) 121531c93a0cSMilan Broz { 1216eb69aca5SHeinz Mauelshagen dm_kcopyd_client_destroy(s->kcopyd_client); 121731c93a0cSMilan Broz s->kcopyd_client = NULL; 121831c93a0cSMilan Broz 12193510cb94SJon Brassow dm_exception_table_exit(&s->pending, pending_cache); 12203510cb94SJon Brassow dm_exception_table_exit(&s->complete, exception_cache); 122131c93a0cSMilan Broz } 122231c93a0cSMilan Broz 1223c1f0c183SMike Snitzer static void __handover_exceptions(struct dm_snapshot *snap_src, 1224c1f0c183SMike Snitzer struct dm_snapshot *snap_dest) 1225c1f0c183SMike Snitzer { 1226c1f0c183SMike Snitzer union { 1227c1f0c183SMike Snitzer struct dm_exception_table table_swap; 1228c1f0c183SMike Snitzer struct dm_exception_store *store_swap; 1229c1f0c183SMike Snitzer } u; 1230c1f0c183SMike Snitzer 1231c1f0c183SMike Snitzer /* 1232c1f0c183SMike Snitzer * Swap all snapshot context information between the two instances. 1233c1f0c183SMike Snitzer */ 1234c1f0c183SMike Snitzer u.table_swap = snap_dest->complete; 1235c1f0c183SMike Snitzer snap_dest->complete = snap_src->complete; 1236c1f0c183SMike Snitzer snap_src->complete = u.table_swap; 1237c1f0c183SMike Snitzer 1238c1f0c183SMike Snitzer u.store_swap = snap_dest->store; 1239c1f0c183SMike Snitzer snap_dest->store = snap_src->store; 1240c1f0c183SMike Snitzer snap_src->store = u.store_swap; 1241c1f0c183SMike Snitzer 1242c1f0c183SMike Snitzer snap_dest->store->snap = snap_dest; 1243c1f0c183SMike Snitzer snap_src->store->snap = snap_src; 1244c1f0c183SMike Snitzer 1245542f9038SMike Snitzer snap_dest->ti->max_io_len = snap_dest->store->chunk_size; 1246c1f0c183SMike Snitzer snap_dest->valid = snap_src->valid; 1247c1f0c183SMike Snitzer 1248c1f0c183SMike Snitzer /* 1249c1f0c183SMike Snitzer * Set source invalid to ensure it receives no further I/O. 1250c1f0c183SMike Snitzer */ 1251c1f0c183SMike Snitzer snap_src->valid = 0; 1252c1f0c183SMike Snitzer } 1253c1f0c183SMike Snitzer 12541da177e4SLinus Torvalds static void snapshot_dtr(struct dm_target *ti) 12551da177e4SLinus Torvalds { 1256cd45daffSMikulas Patocka #ifdef CONFIG_DM_DEBUG 1257cd45daffSMikulas Patocka int i; 1258cd45daffSMikulas Patocka #endif 1259028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 1260c1f0c183SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 12611da177e4SLinus Torvalds 1262c1f0c183SMike Snitzer down_read(&_origins_lock); 1263c1f0c183SMike Snitzer /* Check whether exception handover must be cancelled */ 12649d3b15c4SMikulas Patocka (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); 1265c1f0c183SMike Snitzer if (snap_src && snap_dest && (s == snap_src)) { 1266c1f0c183SMike Snitzer down_write(&snap_dest->lock); 1267c1f0c183SMike Snitzer snap_dest->valid = 0; 1268c1f0c183SMike Snitzer up_write(&snap_dest->lock); 1269c1f0c183SMike Snitzer DMERR("Cancelling snapshot handover."); 1270c1f0c183SMike Snitzer } 1271c1f0c183SMike Snitzer up_read(&_origins_lock); 1272c1f0c183SMike Snitzer 12731e03f97eSMikulas Patocka if (dm_target_is_snapshot_merge(ti)) 12741e03f97eSMikulas Patocka stop_merge(s); 12751e03f97eSMikulas Patocka 1276138728dcSAlasdair G Kergon /* Prevent further origin writes from using this snapshot. */ 1277138728dcSAlasdair G Kergon /* After this returns there can be no new kcopyd jobs. */ 12781da177e4SLinus Torvalds unregister_snapshot(s); 12791da177e4SLinus Torvalds 1280879129d2SMikulas Patocka while (atomic_read(&s->pending_exceptions_count)) 128190fa1527SMikulas Patocka msleep(1); 1282879129d2SMikulas Patocka /* 1283879129d2SMikulas Patocka * Ensure instructions in mempool_destroy aren't reordered 1284879129d2SMikulas Patocka * before atomic_read. 1285879129d2SMikulas Patocka */ 1286879129d2SMikulas Patocka smp_mb(); 1287879129d2SMikulas Patocka 1288cd45daffSMikulas Patocka #ifdef CONFIG_DM_DEBUG 1289cd45daffSMikulas Patocka for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) 1290cd45daffSMikulas Patocka BUG_ON(!hlist_empty(&s->tracked_chunk_hash[i])); 1291cd45daffSMikulas Patocka #endif 1292cd45daffSMikulas Patocka 1293cd45daffSMikulas Patocka mempool_destroy(s->tracked_chunk_pool); 1294cd45daffSMikulas Patocka 129531c93a0cSMilan Broz __free_exceptions(s); 12961da177e4SLinus Torvalds 129792e86812SMikulas Patocka mempool_destroy(s->pending_pool); 129892e86812SMikulas Patocka 1299fee1998eSJonathan Brassow dm_exception_store_destroy(s->store); 1300138728dcSAlasdair G Kergon 1301fc56f6fbSMike Snitzer dm_put_device(ti, s->cow); 1302fc56f6fbSMike Snitzer 1303c2411045SMikulas Patocka dm_put_device(ti, s->origin); 1304c2411045SMikulas Patocka 13051da177e4SLinus Torvalds kfree(s); 13061da177e4SLinus Torvalds } 13071da177e4SLinus Torvalds 13081da177e4SLinus Torvalds /* 13091da177e4SLinus Torvalds * Flush a list of buffers. 13101da177e4SLinus Torvalds */ 13111da177e4SLinus Torvalds static void flush_bios(struct bio *bio) 13121da177e4SLinus Torvalds { 13131da177e4SLinus Torvalds struct bio *n; 13141da177e4SLinus Torvalds 13151da177e4SLinus Torvalds while (bio) { 13161da177e4SLinus Torvalds n = bio->bi_next; 13171da177e4SLinus Torvalds bio->bi_next = NULL; 13181da177e4SLinus Torvalds generic_make_request(bio); 13191da177e4SLinus Torvalds bio = n; 13201da177e4SLinus Torvalds } 13211da177e4SLinus Torvalds } 13221da177e4SLinus Torvalds 1323515ad66cSMikulas Patocka static int do_origin(struct dm_dev *origin, struct bio *bio); 1324515ad66cSMikulas Patocka 1325515ad66cSMikulas Patocka /* 1326515ad66cSMikulas Patocka * Flush a list of buffers. 1327515ad66cSMikulas Patocka */ 1328515ad66cSMikulas Patocka static void retry_origin_bios(struct dm_snapshot *s, struct bio *bio) 1329515ad66cSMikulas Patocka { 1330515ad66cSMikulas Patocka struct bio *n; 1331515ad66cSMikulas Patocka int r; 1332515ad66cSMikulas Patocka 1333515ad66cSMikulas Patocka while (bio) { 1334515ad66cSMikulas Patocka n = bio->bi_next; 1335515ad66cSMikulas Patocka bio->bi_next = NULL; 1336515ad66cSMikulas Patocka r = do_origin(s->origin, bio); 1337515ad66cSMikulas Patocka if (r == DM_MAPIO_REMAPPED) 1338515ad66cSMikulas Patocka generic_make_request(bio); 1339515ad66cSMikulas Patocka bio = n; 1340515ad66cSMikulas Patocka } 1341515ad66cSMikulas Patocka } 1342515ad66cSMikulas Patocka 13431da177e4SLinus Torvalds /* 13441da177e4SLinus Torvalds * Error a list of buffers. 13451da177e4SLinus Torvalds */ 13461da177e4SLinus Torvalds static void error_bios(struct bio *bio) 13471da177e4SLinus Torvalds { 13481da177e4SLinus Torvalds struct bio *n; 13491da177e4SLinus Torvalds 13501da177e4SLinus Torvalds while (bio) { 13511da177e4SLinus Torvalds n = bio->bi_next; 13521da177e4SLinus Torvalds bio->bi_next = NULL; 13536712ecf8SNeilBrown bio_io_error(bio); 13541da177e4SLinus Torvalds bio = n; 13551da177e4SLinus Torvalds } 13561da177e4SLinus Torvalds } 13571da177e4SLinus Torvalds 1358695368acSAlasdair G Kergon static void __invalidate_snapshot(struct dm_snapshot *s, int err) 135976df1c65SAlasdair G Kergon { 136076df1c65SAlasdair G Kergon if (!s->valid) 136176df1c65SAlasdair G Kergon return; 136276df1c65SAlasdair G Kergon 136376df1c65SAlasdair G Kergon if (err == -EIO) 136476df1c65SAlasdair G Kergon DMERR("Invalidating snapshot: Error reading/writing."); 136576df1c65SAlasdair G Kergon else if (err == -ENOMEM) 136676df1c65SAlasdair G Kergon DMERR("Invalidating snapshot: Unable to allocate exception."); 136776df1c65SAlasdair G Kergon 1368493df71cSJonathan Brassow if (s->store->type->drop_snapshot) 1369493df71cSJonathan Brassow s->store->type->drop_snapshot(s->store); 137076df1c65SAlasdair G Kergon 137176df1c65SAlasdair G Kergon s->valid = 0; 137276df1c65SAlasdair G Kergon 1373fc56f6fbSMike Snitzer dm_table_event(s->ti->table); 137476df1c65SAlasdair G Kergon } 137576df1c65SAlasdair G Kergon 1376028867acSAlasdair G Kergon static void pending_complete(struct dm_snap_pending_exception *pe, int success) 13771da177e4SLinus Torvalds { 13781d4989c8SJon Brassow struct dm_exception *e; 13791da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 13809d493fa8SAlasdair G Kergon struct bio *origin_bios = NULL; 13819d493fa8SAlasdair G Kergon struct bio *snapshot_bios = NULL; 1382a6e50b40SMikulas Patocka struct bio *full_bio = NULL; 13839d493fa8SAlasdair G Kergon int error = 0; 13841da177e4SLinus Torvalds 138576df1c65SAlasdair G Kergon if (!success) { 138676df1c65SAlasdair G Kergon /* Read/write error - snapshot is unusable */ 13871da177e4SLinus Torvalds down_write(&s->lock); 1388695368acSAlasdair G Kergon __invalidate_snapshot(s, -EIO); 13899d493fa8SAlasdair G Kergon error = 1; 139076df1c65SAlasdair G Kergon goto out; 139176df1c65SAlasdair G Kergon } 139276df1c65SAlasdair G Kergon 13933510cb94SJon Brassow e = alloc_completed_exception(); 139476df1c65SAlasdair G Kergon if (!e) { 139576df1c65SAlasdair G Kergon down_write(&s->lock); 1396695368acSAlasdair G Kergon __invalidate_snapshot(s, -ENOMEM); 13979d493fa8SAlasdair G Kergon error = 1; 13981da177e4SLinus Torvalds goto out; 13991da177e4SLinus Torvalds } 14001da177e4SLinus Torvalds *e = pe->e; 14011da177e4SLinus Torvalds 14029d493fa8SAlasdair G Kergon down_write(&s->lock); 14039d493fa8SAlasdair G Kergon if (!s->valid) { 14043510cb94SJon Brassow free_completed_exception(e); 14059d493fa8SAlasdair G Kergon error = 1; 14069d493fa8SAlasdair G Kergon goto out; 14079d493fa8SAlasdair G Kergon } 14089d493fa8SAlasdair G Kergon 1409615d1eb9SMike Snitzer /* Check for conflicting reads */ 1410615d1eb9SMike Snitzer __check_for_conflicting_io(s, pe->e.old_chunk); 1411a8d41b59SMikulas Patocka 1412a8d41b59SMikulas Patocka /* 14131da177e4SLinus Torvalds * Add a proper exception, and remove the 14141da177e4SLinus Torvalds * in-flight exception from the list. 14151da177e4SLinus Torvalds */ 14163510cb94SJon Brassow dm_insert_exception(&s->complete, e); 14171da177e4SLinus Torvalds 14181da177e4SLinus Torvalds out: 14193510cb94SJon Brassow dm_remove_exception(&pe->e); 14209d493fa8SAlasdair G Kergon snapshot_bios = bio_list_get(&pe->snapshot_bios); 1421515ad66cSMikulas Patocka origin_bios = bio_list_get(&pe->origin_bios); 1422a6e50b40SMikulas Patocka full_bio = pe->full_bio; 1423a6e50b40SMikulas Patocka if (full_bio) { 1424a6e50b40SMikulas Patocka full_bio->bi_end_io = pe->full_bio_end_io; 1425a6e50b40SMikulas Patocka full_bio->bi_private = pe->full_bio_private; 1426a6e50b40SMikulas Patocka } 1427515ad66cSMikulas Patocka free_pending_exception(pe); 1428b4b610f6SAlasdair G Kergon 142973dfd078SMikulas Patocka increment_pending_exceptions_done_count(); 143073dfd078SMikulas Patocka 14319d493fa8SAlasdair G Kergon up_write(&s->lock); 14329d493fa8SAlasdair G Kergon 14339d493fa8SAlasdair G Kergon /* Submit any pending write bios */ 1434a6e50b40SMikulas Patocka if (error) { 1435a6e50b40SMikulas Patocka if (full_bio) 1436a6e50b40SMikulas Patocka bio_io_error(full_bio); 14379d493fa8SAlasdair G Kergon error_bios(snapshot_bios); 1438a6e50b40SMikulas Patocka } else { 1439a6e50b40SMikulas Patocka if (full_bio) 1440a6e50b40SMikulas Patocka bio_endio(full_bio, 0); 14419d493fa8SAlasdair G Kergon flush_bios(snapshot_bios); 1442a6e50b40SMikulas Patocka } 14439d493fa8SAlasdair G Kergon 1444515ad66cSMikulas Patocka retry_origin_bios(s, origin_bios); 14451da177e4SLinus Torvalds } 14461da177e4SLinus Torvalds 14471da177e4SLinus Torvalds static void commit_callback(void *context, int success) 14481da177e4SLinus Torvalds { 1449028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = context; 1450028867acSAlasdair G Kergon 14511da177e4SLinus Torvalds pending_complete(pe, success); 14521da177e4SLinus Torvalds } 14531da177e4SLinus Torvalds 14541da177e4SLinus Torvalds /* 14551da177e4SLinus Torvalds * Called when the copy I/O has finished. kcopyd actually runs 14561da177e4SLinus Torvalds * this code so don't block. 14571da177e4SLinus Torvalds */ 14584cdc1d1fSAlasdair G Kergon static void copy_callback(int read_err, unsigned long write_err, void *context) 14591da177e4SLinus Torvalds { 1460028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = context; 14611da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 14621da177e4SLinus Torvalds 14631da177e4SLinus Torvalds if (read_err || write_err) 14641da177e4SLinus Torvalds pending_complete(pe, 0); 14651da177e4SLinus Torvalds 14661da177e4SLinus Torvalds else 14671da177e4SLinus Torvalds /* Update the metadata if we are persistent */ 1468493df71cSJonathan Brassow s->store->type->commit_exception(s->store, &pe->e, 1469b2a11465SJonathan Brassow commit_callback, pe); 14701da177e4SLinus Torvalds } 14711da177e4SLinus Torvalds 14721da177e4SLinus Torvalds /* 14731da177e4SLinus Torvalds * Dispatches the copy operation to kcopyd. 14741da177e4SLinus Torvalds */ 1475028867acSAlasdair G Kergon static void start_copy(struct dm_snap_pending_exception *pe) 14761da177e4SLinus Torvalds { 14771da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 147822a1ceb1SHeinz Mauelshagen struct dm_io_region src, dest; 14791da177e4SLinus Torvalds struct block_device *bdev = s->origin->bdev; 14801da177e4SLinus Torvalds sector_t dev_size; 14811da177e4SLinus Torvalds 14821da177e4SLinus Torvalds dev_size = get_dev_size(bdev); 14831da177e4SLinus Torvalds 14841da177e4SLinus Torvalds src.bdev = bdev; 148571fab00aSJonathan Brassow src.sector = chunk_to_sector(s->store, pe->e.old_chunk); 1486df96eee6SMikulas Patocka src.count = min((sector_t)s->store->chunk_size, dev_size - src.sector); 14871da177e4SLinus Torvalds 1488fc56f6fbSMike Snitzer dest.bdev = s->cow->bdev; 148971fab00aSJonathan Brassow dest.sector = chunk_to_sector(s->store, pe->e.new_chunk); 14901da177e4SLinus Torvalds dest.count = src.count; 14911da177e4SLinus Torvalds 14921da177e4SLinus Torvalds /* Hand over to kcopyd */ 1493a2d2b034SJonathan Brassow dm_kcopyd_copy(s->kcopyd_client, &src, 1, &dest, 0, copy_callback, pe); 14941da177e4SLinus Torvalds } 14951da177e4SLinus Torvalds 1496a6e50b40SMikulas Patocka static void full_bio_end_io(struct bio *bio, int error) 1497a6e50b40SMikulas Patocka { 1498a6e50b40SMikulas Patocka void *callback_data = bio->bi_private; 1499a6e50b40SMikulas Patocka 1500a6e50b40SMikulas Patocka dm_kcopyd_do_callback(callback_data, 0, error ? 1 : 0); 1501a6e50b40SMikulas Patocka } 1502a6e50b40SMikulas Patocka 1503a6e50b40SMikulas Patocka static void start_full_bio(struct dm_snap_pending_exception *pe, 1504a6e50b40SMikulas Patocka struct bio *bio) 1505a6e50b40SMikulas Patocka { 1506a6e50b40SMikulas Patocka struct dm_snapshot *s = pe->snap; 1507a6e50b40SMikulas Patocka void *callback_data; 1508a6e50b40SMikulas Patocka 1509a6e50b40SMikulas Patocka pe->full_bio = bio; 1510a6e50b40SMikulas Patocka pe->full_bio_end_io = bio->bi_end_io; 1511a6e50b40SMikulas Patocka pe->full_bio_private = bio->bi_private; 1512a6e50b40SMikulas Patocka 1513a6e50b40SMikulas Patocka callback_data = dm_kcopyd_prepare_callback(s->kcopyd_client, 1514a6e50b40SMikulas Patocka copy_callback, pe); 1515a6e50b40SMikulas Patocka 1516a6e50b40SMikulas Patocka bio->bi_end_io = full_bio_end_io; 1517a6e50b40SMikulas Patocka bio->bi_private = callback_data; 1518a6e50b40SMikulas Patocka 1519a6e50b40SMikulas Patocka generic_make_request(bio); 1520a6e50b40SMikulas Patocka } 1521a6e50b40SMikulas Patocka 15222913808eSMikulas Patocka static struct dm_snap_pending_exception * 15232913808eSMikulas Patocka __lookup_pending_exception(struct dm_snapshot *s, chunk_t chunk) 15242913808eSMikulas Patocka { 15253510cb94SJon Brassow struct dm_exception *e = dm_lookup_exception(&s->pending, chunk); 15262913808eSMikulas Patocka 15272913808eSMikulas Patocka if (!e) 15282913808eSMikulas Patocka return NULL; 15292913808eSMikulas Patocka 15302913808eSMikulas Patocka return container_of(e, struct dm_snap_pending_exception, e); 15312913808eSMikulas Patocka } 15322913808eSMikulas Patocka 15331da177e4SLinus Torvalds /* 15341da177e4SLinus Torvalds * Looks to see if this snapshot already has a pending exception 15351da177e4SLinus Torvalds * for this chunk, otherwise it allocates a new one and inserts 15361da177e4SLinus Torvalds * it into the pending table. 15371da177e4SLinus Torvalds * 15381da177e4SLinus Torvalds * NOTE: a write lock must be held on snap->lock before calling 15391da177e4SLinus Torvalds * this. 15401da177e4SLinus Torvalds */ 1541028867acSAlasdair G Kergon static struct dm_snap_pending_exception * 1542c6621392SMikulas Patocka __find_pending_exception(struct dm_snapshot *s, 1543c6621392SMikulas Patocka struct dm_snap_pending_exception *pe, chunk_t chunk) 15441da177e4SLinus Torvalds { 1545c6621392SMikulas Patocka struct dm_snap_pending_exception *pe2; 154676df1c65SAlasdair G Kergon 15472913808eSMikulas Patocka pe2 = __lookup_pending_exception(s, chunk); 15482913808eSMikulas Patocka if (pe2) { 15491da177e4SLinus Torvalds free_pending_exception(pe); 15502913808eSMikulas Patocka return pe2; 155176df1c65SAlasdair G Kergon } 155276df1c65SAlasdair G Kergon 15531da177e4SLinus Torvalds pe->e.old_chunk = chunk; 15541da177e4SLinus Torvalds bio_list_init(&pe->origin_bios); 15551da177e4SLinus Torvalds bio_list_init(&pe->snapshot_bios); 15561da177e4SLinus Torvalds pe->started = 0; 1557a6e50b40SMikulas Patocka pe->full_bio = NULL; 15581da177e4SLinus Torvalds 1559493df71cSJonathan Brassow if (s->store->type->prepare_exception(s->store, &pe->e)) { 15601da177e4SLinus Torvalds free_pending_exception(pe); 15611da177e4SLinus Torvalds return NULL; 15621da177e4SLinus Torvalds } 15631da177e4SLinus Torvalds 15643510cb94SJon Brassow dm_insert_exception(&s->pending, &pe->e); 15651da177e4SLinus Torvalds 15661da177e4SLinus Torvalds return pe; 15671da177e4SLinus Torvalds } 15681da177e4SLinus Torvalds 15691d4989c8SJon Brassow static void remap_exception(struct dm_snapshot *s, struct dm_exception *e, 1570d74f81f8SMilan Broz struct bio *bio, chunk_t chunk) 15711da177e4SLinus Torvalds { 1572fc56f6fbSMike Snitzer bio->bi_bdev = s->cow->bdev; 157371fab00aSJonathan Brassow bio->bi_sector = chunk_to_sector(s->store, 157471fab00aSJonathan Brassow dm_chunk_number(e->new_chunk) + 1575d74f81f8SMilan Broz (chunk - e->old_chunk)) + 157671fab00aSJonathan Brassow (bio->bi_sector & 157771fab00aSJonathan Brassow s->store->chunk_mask); 15781da177e4SLinus Torvalds } 15791da177e4SLinus Torvalds 15801da177e4SLinus Torvalds static int snapshot_map(struct dm_target *ti, struct bio *bio, 15811da177e4SLinus Torvalds union map_info *map_context) 15821da177e4SLinus Torvalds { 15831d4989c8SJon Brassow struct dm_exception *e; 1584028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 1585d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED; 15861da177e4SLinus Torvalds chunk_t chunk; 1587028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = NULL; 15881da177e4SLinus Torvalds 1589d87f4c14STejun Heo if (bio->bi_rw & REQ_FLUSH) { 1590fc56f6fbSMike Snitzer bio->bi_bdev = s->cow->bdev; 1591494b3ee7SMikulas Patocka return DM_MAPIO_REMAPPED; 1592494b3ee7SMikulas Patocka } 1593494b3ee7SMikulas Patocka 159471fab00aSJonathan Brassow chunk = sector_to_chunk(s->store, bio->bi_sector); 15951da177e4SLinus Torvalds 15961da177e4SLinus Torvalds /* Full snapshots are not usable */ 159776df1c65SAlasdair G Kergon /* To get here the table must be live so s->active is always set. */ 15981da177e4SLinus Torvalds if (!s->valid) 1599f6a80ea8SAlasdair G Kergon return -EIO; 16001da177e4SLinus Torvalds 16011da177e4SLinus Torvalds /* FIXME: should only take write lock if we need 16021da177e4SLinus Torvalds * to copy an exception */ 16031da177e4SLinus Torvalds down_write(&s->lock); 16041da177e4SLinus Torvalds 160576df1c65SAlasdair G Kergon if (!s->valid) { 160676df1c65SAlasdair G Kergon r = -EIO; 160776df1c65SAlasdair G Kergon goto out_unlock; 160876df1c65SAlasdair G Kergon } 160976df1c65SAlasdair G Kergon 16101da177e4SLinus Torvalds /* If the block is already remapped - use that, else remap it */ 16113510cb94SJon Brassow e = dm_lookup_exception(&s->complete, chunk); 16121da177e4SLinus Torvalds if (e) { 1613d74f81f8SMilan Broz remap_exception(s, e, bio, chunk); 161476df1c65SAlasdair G Kergon goto out_unlock; 161576df1c65SAlasdair G Kergon } 16161da177e4SLinus Torvalds 1617ba40a2aaSAlasdair G Kergon /* 1618ba40a2aaSAlasdair G Kergon * Write to snapshot - higher level takes care of RW/RO 1619ba40a2aaSAlasdair G Kergon * flags so we should only get this if we are 1620ba40a2aaSAlasdair G Kergon * writeable. 1621ba40a2aaSAlasdair G Kergon */ 1622ba40a2aaSAlasdair G Kergon if (bio_rw(bio) == WRITE) { 16232913808eSMikulas Patocka pe = __lookup_pending_exception(s, chunk); 16242913808eSMikulas Patocka if (!pe) { 1625c6621392SMikulas Patocka up_write(&s->lock); 1626c6621392SMikulas Patocka pe = alloc_pending_exception(s); 1627c6621392SMikulas Patocka down_write(&s->lock); 1628c6621392SMikulas Patocka 1629c6621392SMikulas Patocka if (!s->valid) { 1630c6621392SMikulas Patocka free_pending_exception(pe); 1631c6621392SMikulas Patocka r = -EIO; 1632c6621392SMikulas Patocka goto out_unlock; 1633c6621392SMikulas Patocka } 1634c6621392SMikulas Patocka 16353510cb94SJon Brassow e = dm_lookup_exception(&s->complete, chunk); 163635bf659bSMikulas Patocka if (e) { 163735bf659bSMikulas Patocka free_pending_exception(pe); 163835bf659bSMikulas Patocka remap_exception(s, e, bio, chunk); 163935bf659bSMikulas Patocka goto out_unlock; 164035bf659bSMikulas Patocka } 164135bf659bSMikulas Patocka 1642c6621392SMikulas Patocka pe = __find_pending_exception(s, pe, chunk); 16431da177e4SLinus Torvalds if (!pe) { 1644695368acSAlasdair G Kergon __invalidate_snapshot(s, -ENOMEM); 16451da177e4SLinus Torvalds r = -EIO; 164676df1c65SAlasdair G Kergon goto out_unlock; 164776df1c65SAlasdair G Kergon } 16482913808eSMikulas Patocka } 164976df1c65SAlasdair G Kergon 1650d74f81f8SMilan Broz remap_exception(s, &pe->e, bio, chunk); 16511da177e4SLinus Torvalds 1652d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 1653ba40a2aaSAlasdair G Kergon 1654a6e50b40SMikulas Patocka if (!pe->started && 1655a6e50b40SMikulas Patocka bio->bi_size == (s->store->chunk_size << SECTOR_SHIFT)) { 1656a6e50b40SMikulas Patocka pe->started = 1; 1657a6e50b40SMikulas Patocka up_write(&s->lock); 1658a6e50b40SMikulas Patocka start_full_bio(pe, bio); 1659a6e50b40SMikulas Patocka goto out; 1660a6e50b40SMikulas Patocka } 1661a6e50b40SMikulas Patocka 1662a6e50b40SMikulas Patocka bio_list_add(&pe->snapshot_bios, bio); 1663a6e50b40SMikulas Patocka 16641da177e4SLinus Torvalds if (!pe->started) { 16651da177e4SLinus Torvalds /* this is protected by snap->lock */ 16661da177e4SLinus Torvalds pe->started = 1; 166776df1c65SAlasdair G Kergon up_write(&s->lock); 166876df1c65SAlasdair G Kergon start_copy(pe); 1669ba40a2aaSAlasdair G Kergon goto out; 1670ba40a2aaSAlasdair G Kergon } 1671cd45daffSMikulas Patocka } else { 16721da177e4SLinus Torvalds bio->bi_bdev = s->origin->bdev; 1673cd45daffSMikulas Patocka map_context->ptr = track_chunk(s, chunk); 1674cd45daffSMikulas Patocka } 16751da177e4SLinus Torvalds 1676ba40a2aaSAlasdair G Kergon out_unlock: 1677ba40a2aaSAlasdair G Kergon up_write(&s->lock); 1678ba40a2aaSAlasdair G Kergon out: 16791da177e4SLinus Torvalds return r; 16801da177e4SLinus Torvalds } 16811da177e4SLinus Torvalds 16823452c2a1SMikulas Patocka /* 16833452c2a1SMikulas Patocka * A snapshot-merge target behaves like a combination of a snapshot 16843452c2a1SMikulas Patocka * target and a snapshot-origin target. It only generates new 16853452c2a1SMikulas Patocka * exceptions in other snapshots and not in the one that is being 16863452c2a1SMikulas Patocka * merged. 16873452c2a1SMikulas Patocka * 16883452c2a1SMikulas Patocka * For each chunk, if there is an existing exception, it is used to 16893452c2a1SMikulas Patocka * redirect I/O to the cow device. Otherwise I/O is sent to the origin, 16903452c2a1SMikulas Patocka * which in turn might generate exceptions in other snapshots. 16919fe86254SMikulas Patocka * If merging is currently taking place on the chunk in question, the 16929fe86254SMikulas Patocka * I/O is deferred by adding it to s->bios_queued_during_merge. 16933452c2a1SMikulas Patocka */ 16943452c2a1SMikulas Patocka static int snapshot_merge_map(struct dm_target *ti, struct bio *bio, 16953452c2a1SMikulas Patocka union map_info *map_context) 16963452c2a1SMikulas Patocka { 16973452c2a1SMikulas Patocka struct dm_exception *e; 16983452c2a1SMikulas Patocka struct dm_snapshot *s = ti->private; 16993452c2a1SMikulas Patocka int r = DM_MAPIO_REMAPPED; 17003452c2a1SMikulas Patocka chunk_t chunk; 17013452c2a1SMikulas Patocka 1702d87f4c14STejun Heo if (bio->bi_rw & REQ_FLUSH) { 170357cba5d3SMike Snitzer if (!map_context->target_request_nr) 170410b8106aSMike Snitzer bio->bi_bdev = s->origin->bdev; 170510b8106aSMike Snitzer else 170610b8106aSMike Snitzer bio->bi_bdev = s->cow->bdev; 170710b8106aSMike Snitzer map_context->ptr = NULL; 170810b8106aSMike Snitzer return DM_MAPIO_REMAPPED; 170910b8106aSMike Snitzer } 171010b8106aSMike Snitzer 17113452c2a1SMikulas Patocka chunk = sector_to_chunk(s->store, bio->bi_sector); 17123452c2a1SMikulas Patocka 17139fe86254SMikulas Patocka down_write(&s->lock); 17143452c2a1SMikulas Patocka 1715d2fdb776SMikulas Patocka /* Full merging snapshots are redirected to the origin */ 1716d2fdb776SMikulas Patocka if (!s->valid) 1717d2fdb776SMikulas Patocka goto redirect_to_origin; 17183452c2a1SMikulas Patocka 17193452c2a1SMikulas Patocka /* If the block is already remapped - use that */ 17203452c2a1SMikulas Patocka e = dm_lookup_exception(&s->complete, chunk); 17213452c2a1SMikulas Patocka if (e) { 17229fe86254SMikulas Patocka /* Queue writes overlapping with chunks being merged */ 17239fe86254SMikulas Patocka if (bio_rw(bio) == WRITE && 17249fe86254SMikulas Patocka chunk >= s->first_merging_chunk && 17259fe86254SMikulas Patocka chunk < (s->first_merging_chunk + 17269fe86254SMikulas Patocka s->num_merging_chunks)) { 17279fe86254SMikulas Patocka bio->bi_bdev = s->origin->bdev; 17289fe86254SMikulas Patocka bio_list_add(&s->bios_queued_during_merge, bio); 17299fe86254SMikulas Patocka r = DM_MAPIO_SUBMITTED; 17309fe86254SMikulas Patocka goto out_unlock; 17319fe86254SMikulas Patocka } 173217aa0332SMikulas Patocka 17333452c2a1SMikulas Patocka remap_exception(s, e, bio, chunk); 173417aa0332SMikulas Patocka 173517aa0332SMikulas Patocka if (bio_rw(bio) == WRITE) 173617aa0332SMikulas Patocka map_context->ptr = track_chunk(s, chunk); 17373452c2a1SMikulas Patocka goto out_unlock; 17383452c2a1SMikulas Patocka } 17393452c2a1SMikulas Patocka 1740d2fdb776SMikulas Patocka redirect_to_origin: 17413452c2a1SMikulas Patocka bio->bi_bdev = s->origin->bdev; 17423452c2a1SMikulas Patocka 17433452c2a1SMikulas Patocka if (bio_rw(bio) == WRITE) { 17449fe86254SMikulas Patocka up_write(&s->lock); 17453452c2a1SMikulas Patocka return do_origin(s->origin, bio); 17463452c2a1SMikulas Patocka } 17473452c2a1SMikulas Patocka 17483452c2a1SMikulas Patocka out_unlock: 17499fe86254SMikulas Patocka up_write(&s->lock); 17503452c2a1SMikulas Patocka 17513452c2a1SMikulas Patocka return r; 17523452c2a1SMikulas Patocka } 17533452c2a1SMikulas Patocka 1754cd45daffSMikulas Patocka static int snapshot_end_io(struct dm_target *ti, struct bio *bio, 1755cd45daffSMikulas Patocka int error, union map_info *map_context) 1756cd45daffSMikulas Patocka { 1757cd45daffSMikulas Patocka struct dm_snapshot *s = ti->private; 1758cd45daffSMikulas Patocka struct dm_snap_tracked_chunk *c = map_context->ptr; 1759cd45daffSMikulas Patocka 1760cd45daffSMikulas Patocka if (c) 1761cd45daffSMikulas Patocka stop_tracking_chunk(s, c); 1762cd45daffSMikulas Patocka 1763cd45daffSMikulas Patocka return 0; 1764cd45daffSMikulas Patocka } 1765cd45daffSMikulas Patocka 17661e03f97eSMikulas Patocka static void snapshot_merge_presuspend(struct dm_target *ti) 17671e03f97eSMikulas Patocka { 17681e03f97eSMikulas Patocka struct dm_snapshot *s = ti->private; 17691e03f97eSMikulas Patocka 17701e03f97eSMikulas Patocka stop_merge(s); 17711e03f97eSMikulas Patocka } 17721e03f97eSMikulas Patocka 1773c1f0c183SMike Snitzer static int snapshot_preresume(struct dm_target *ti) 1774c1f0c183SMike Snitzer { 1775c1f0c183SMike Snitzer int r = 0; 1776c1f0c183SMike Snitzer struct dm_snapshot *s = ti->private; 1777c1f0c183SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 1778c1f0c183SMike Snitzer 1779c1f0c183SMike Snitzer down_read(&_origins_lock); 17809d3b15c4SMikulas Patocka (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); 1781c1f0c183SMike Snitzer if (snap_src && snap_dest) { 1782c1f0c183SMike Snitzer down_read(&snap_src->lock); 1783c1f0c183SMike Snitzer if (s == snap_src) { 1784c1f0c183SMike Snitzer DMERR("Unable to resume snapshot source until " 1785c1f0c183SMike Snitzer "handover completes."); 1786c1f0c183SMike Snitzer r = -EINVAL; 1787b83b2f29SMike Snitzer } else if (!dm_suspended(snap_src->ti)) { 1788c1f0c183SMike Snitzer DMERR("Unable to perform snapshot handover until " 1789c1f0c183SMike Snitzer "source is suspended."); 1790c1f0c183SMike Snitzer r = -EINVAL; 1791c1f0c183SMike Snitzer } 1792c1f0c183SMike Snitzer up_read(&snap_src->lock); 1793c1f0c183SMike Snitzer } 1794c1f0c183SMike Snitzer up_read(&_origins_lock); 1795c1f0c183SMike Snitzer 1796c1f0c183SMike Snitzer return r; 1797c1f0c183SMike Snitzer } 1798c1f0c183SMike Snitzer 17991da177e4SLinus Torvalds static void snapshot_resume(struct dm_target *ti) 18001da177e4SLinus Torvalds { 1801028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 1802c1f0c183SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 1803c1f0c183SMike Snitzer 1804c1f0c183SMike Snitzer down_read(&_origins_lock); 18059d3b15c4SMikulas Patocka (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); 1806c1f0c183SMike Snitzer if (snap_src && snap_dest) { 1807c1f0c183SMike Snitzer down_write(&snap_src->lock); 1808c1f0c183SMike Snitzer down_write_nested(&snap_dest->lock, SINGLE_DEPTH_NESTING); 1809c1f0c183SMike Snitzer __handover_exceptions(snap_src, snap_dest); 1810c1f0c183SMike Snitzer up_write(&snap_dest->lock); 1811c1f0c183SMike Snitzer up_write(&snap_src->lock); 1812c1f0c183SMike Snitzer } 1813c1f0c183SMike Snitzer up_read(&_origins_lock); 1814c1f0c183SMike Snitzer 1815c1f0c183SMike Snitzer /* Now we have correct chunk size, reregister */ 1816c1f0c183SMike Snitzer reregister_snapshot(s); 18171da177e4SLinus Torvalds 1818aa14edebSAlasdair G Kergon down_write(&s->lock); 1819aa14edebSAlasdair G Kergon s->active = 1; 1820aa14edebSAlasdair G Kergon up_write(&s->lock); 18211da177e4SLinus Torvalds } 18221da177e4SLinus Torvalds 1823542f9038SMike Snitzer static uint32_t get_origin_minimum_chunksize(struct block_device *bdev) 18241e03f97eSMikulas Patocka { 1825542f9038SMike Snitzer uint32_t min_chunksize; 18261e03f97eSMikulas Patocka 18271e03f97eSMikulas Patocka down_read(&_origins_lock); 18281e03f97eSMikulas Patocka min_chunksize = __minimum_chunk_size(__lookup_origin(bdev)); 18291e03f97eSMikulas Patocka up_read(&_origins_lock); 18301e03f97eSMikulas Patocka 18311e03f97eSMikulas Patocka return min_chunksize; 18321e03f97eSMikulas Patocka } 18331e03f97eSMikulas Patocka 18341e03f97eSMikulas Patocka static void snapshot_merge_resume(struct dm_target *ti) 18351e03f97eSMikulas Patocka { 18361e03f97eSMikulas Patocka struct dm_snapshot *s = ti->private; 18371e03f97eSMikulas Patocka 18381e03f97eSMikulas Patocka /* 18391e03f97eSMikulas Patocka * Handover exceptions from existing snapshot. 18401e03f97eSMikulas Patocka */ 18411e03f97eSMikulas Patocka snapshot_resume(ti); 18421e03f97eSMikulas Patocka 18431e03f97eSMikulas Patocka /* 1844542f9038SMike Snitzer * snapshot-merge acts as an origin, so set ti->max_io_len 18451e03f97eSMikulas Patocka */ 1846542f9038SMike Snitzer ti->max_io_len = get_origin_minimum_chunksize(s->origin->bdev); 18471e03f97eSMikulas Patocka 18481e03f97eSMikulas Patocka start_merge(s); 18491e03f97eSMikulas Patocka } 18501e03f97eSMikulas Patocka 18511da177e4SLinus Torvalds static int snapshot_status(struct dm_target *ti, status_type_t type, 18521da177e4SLinus Torvalds char *result, unsigned int maxlen) 18531da177e4SLinus Torvalds { 18542e4a31dfSJonathan Brassow unsigned sz = 0; 1855028867acSAlasdair G Kergon struct dm_snapshot *snap = ti->private; 18561da177e4SLinus Torvalds 18571da177e4SLinus Torvalds switch (type) { 18581da177e4SLinus Torvalds case STATUSTYPE_INFO: 185994e76572SMikulas Patocka 186094e76572SMikulas Patocka down_write(&snap->lock); 186194e76572SMikulas Patocka 18621da177e4SLinus Torvalds if (!snap->valid) 18632e4a31dfSJonathan Brassow DMEMIT("Invalid"); 1864d8ddb1cfSMike Snitzer else if (snap->merge_failed) 1865d8ddb1cfSMike Snitzer DMEMIT("Merge failed"); 18661da177e4SLinus Torvalds else { 1867985903bbSMike Snitzer if (snap->store->type->usage) { 1868985903bbSMike Snitzer sector_t total_sectors, sectors_allocated, 1869985903bbSMike Snitzer metadata_sectors; 1870985903bbSMike Snitzer snap->store->type->usage(snap->store, 1871985903bbSMike Snitzer &total_sectors, 1872985903bbSMike Snitzer §ors_allocated, 1873985903bbSMike Snitzer &metadata_sectors); 1874985903bbSMike Snitzer DMEMIT("%llu/%llu %llu", 1875985903bbSMike Snitzer (unsigned long long)sectors_allocated, 1876985903bbSMike Snitzer (unsigned long long)total_sectors, 1877985903bbSMike Snitzer (unsigned long long)metadata_sectors); 18781da177e4SLinus Torvalds } 18791da177e4SLinus Torvalds else 18802e4a31dfSJonathan Brassow DMEMIT("Unknown"); 18811da177e4SLinus Torvalds } 188294e76572SMikulas Patocka 188394e76572SMikulas Patocka up_write(&snap->lock); 188494e76572SMikulas Patocka 18851da177e4SLinus Torvalds break; 18861da177e4SLinus Torvalds 18871da177e4SLinus Torvalds case STATUSTYPE_TABLE: 18881da177e4SLinus Torvalds /* 18891da177e4SLinus Torvalds * kdevname returns a static pointer so we need 18901da177e4SLinus Torvalds * to make private copies if the output is to 18911da177e4SLinus Torvalds * make sense. 18921da177e4SLinus Torvalds */ 1893fc56f6fbSMike Snitzer DMEMIT("%s %s", snap->origin->name, snap->cow->name); 18941e302a92SJonathan Brassow snap->store->type->status(snap->store, type, result + sz, 18951e302a92SJonathan Brassow maxlen - sz); 18961da177e4SLinus Torvalds break; 18971da177e4SLinus Torvalds } 18981da177e4SLinus Torvalds 18991da177e4SLinus Torvalds return 0; 19001da177e4SLinus Torvalds } 19011da177e4SLinus Torvalds 19028811f46cSMike Snitzer static int snapshot_iterate_devices(struct dm_target *ti, 19038811f46cSMike Snitzer iterate_devices_callout_fn fn, void *data) 19048811f46cSMike Snitzer { 19058811f46cSMike Snitzer struct dm_snapshot *snap = ti->private; 19061e5554c8SMikulas Patocka int r; 19078811f46cSMike Snitzer 19081e5554c8SMikulas Patocka r = fn(ti, snap->origin, 0, ti->len, data); 19091e5554c8SMikulas Patocka 19101e5554c8SMikulas Patocka if (!r) 19111e5554c8SMikulas Patocka r = fn(ti, snap->cow, 0, get_dev_size(snap->cow->bdev), data); 19121e5554c8SMikulas Patocka 19131e5554c8SMikulas Patocka return r; 19148811f46cSMike Snitzer } 19158811f46cSMike Snitzer 19168811f46cSMike Snitzer 19171da177e4SLinus Torvalds /*----------------------------------------------------------------- 19181da177e4SLinus Torvalds * Origin methods 19191da177e4SLinus Torvalds *---------------------------------------------------------------*/ 19209eaae8ffSMikulas Patocka 19219eaae8ffSMikulas Patocka /* 19229eaae8ffSMikulas Patocka * If no exceptions need creating, DM_MAPIO_REMAPPED is returned and any 19239eaae8ffSMikulas Patocka * supplied bio was ignored. The caller may submit it immediately. 19249eaae8ffSMikulas Patocka * (No remapping actually occurs as the origin is always a direct linear 19259eaae8ffSMikulas Patocka * map.) 19269eaae8ffSMikulas Patocka * 19279eaae8ffSMikulas Patocka * If further exceptions are required, DM_MAPIO_SUBMITTED is returned 19289eaae8ffSMikulas Patocka * and any supplied bio is added to a list to be submitted once all 19299eaae8ffSMikulas Patocka * the necessary exceptions exist. 19309eaae8ffSMikulas Patocka */ 19319eaae8ffSMikulas Patocka static int __origin_write(struct list_head *snapshots, sector_t sector, 19329eaae8ffSMikulas Patocka struct bio *bio) 19331da177e4SLinus Torvalds { 1934515ad66cSMikulas Patocka int r = DM_MAPIO_REMAPPED; 19351da177e4SLinus Torvalds struct dm_snapshot *snap; 19361d4989c8SJon Brassow struct dm_exception *e; 1937515ad66cSMikulas Patocka struct dm_snap_pending_exception *pe; 1938515ad66cSMikulas Patocka struct dm_snap_pending_exception *pe_to_start_now = NULL; 1939515ad66cSMikulas Patocka struct dm_snap_pending_exception *pe_to_start_last = NULL; 19401da177e4SLinus Torvalds chunk_t chunk; 19411da177e4SLinus Torvalds 19421da177e4SLinus Torvalds /* Do all the snapshots on this origin */ 19431da177e4SLinus Torvalds list_for_each_entry (snap, snapshots, list) { 19443452c2a1SMikulas Patocka /* 19453452c2a1SMikulas Patocka * Don't make new exceptions in a merging snapshot 19463452c2a1SMikulas Patocka * because it has effectively been deleted 19473452c2a1SMikulas Patocka */ 19483452c2a1SMikulas Patocka if (dm_target_is_snapshot_merge(snap->ti)) 19493452c2a1SMikulas Patocka continue; 19503452c2a1SMikulas Patocka 195176df1c65SAlasdair G Kergon down_write(&snap->lock); 195276df1c65SAlasdair G Kergon 1953aa14edebSAlasdair G Kergon /* Only deal with valid and active snapshots */ 1954aa14edebSAlasdair G Kergon if (!snap->valid || !snap->active) 195576df1c65SAlasdair G Kergon goto next_snapshot; 19561da177e4SLinus Torvalds 1957d5e404c1SAlasdair G Kergon /* Nothing to do if writing beyond end of snapshot */ 19589eaae8ffSMikulas Patocka if (sector >= dm_table_get_size(snap->ti->table)) 195976df1c65SAlasdair G Kergon goto next_snapshot; 19601da177e4SLinus Torvalds 19611da177e4SLinus Torvalds /* 19621da177e4SLinus Torvalds * Remember, different snapshots can have 19631da177e4SLinus Torvalds * different chunk sizes. 19641da177e4SLinus Torvalds */ 19659eaae8ffSMikulas Patocka chunk = sector_to_chunk(snap->store, sector); 19661da177e4SLinus Torvalds 19671da177e4SLinus Torvalds /* 19681da177e4SLinus Torvalds * Check exception table to see if block 19691da177e4SLinus Torvalds * is already remapped in this snapshot 19701da177e4SLinus Torvalds * and trigger an exception if not. 19711da177e4SLinus Torvalds */ 19723510cb94SJon Brassow e = dm_lookup_exception(&snap->complete, chunk); 197376df1c65SAlasdair G Kergon if (e) 197476df1c65SAlasdair G Kergon goto next_snapshot; 197576df1c65SAlasdair G Kergon 19762913808eSMikulas Patocka pe = __lookup_pending_exception(snap, chunk); 19772913808eSMikulas Patocka if (!pe) { 1978c6621392SMikulas Patocka up_write(&snap->lock); 1979c6621392SMikulas Patocka pe = alloc_pending_exception(snap); 1980c6621392SMikulas Patocka down_write(&snap->lock); 1981c6621392SMikulas Patocka 1982c6621392SMikulas Patocka if (!snap->valid) { 1983c6621392SMikulas Patocka free_pending_exception(pe); 1984c6621392SMikulas Patocka goto next_snapshot; 1985c6621392SMikulas Patocka } 1986c6621392SMikulas Patocka 19873510cb94SJon Brassow e = dm_lookup_exception(&snap->complete, chunk); 198835bf659bSMikulas Patocka if (e) { 198935bf659bSMikulas Patocka free_pending_exception(pe); 199035bf659bSMikulas Patocka goto next_snapshot; 199135bf659bSMikulas Patocka } 199235bf659bSMikulas Patocka 1993c6621392SMikulas Patocka pe = __find_pending_exception(snap, pe, chunk); 19941da177e4SLinus Torvalds if (!pe) { 1995695368acSAlasdair G Kergon __invalidate_snapshot(snap, -ENOMEM); 199676df1c65SAlasdair G Kergon goto next_snapshot; 199776df1c65SAlasdair G Kergon } 19982913808eSMikulas Patocka } 19991da177e4SLinus Torvalds 2000d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 200176df1c65SAlasdair G Kergon 2002515ad66cSMikulas Patocka /* 2003515ad66cSMikulas Patocka * If an origin bio was supplied, queue it to wait for the 2004515ad66cSMikulas Patocka * completion of this exception, and start this one last, 2005515ad66cSMikulas Patocka * at the end of the function. 2006515ad66cSMikulas Patocka */ 2007515ad66cSMikulas Patocka if (bio) { 2008515ad66cSMikulas Patocka bio_list_add(&pe->origin_bios, bio); 2009515ad66cSMikulas Patocka bio = NULL; 2010515ad66cSMikulas Patocka 2011515ad66cSMikulas Patocka if (!pe->started) { 2012515ad66cSMikulas Patocka pe->started = 1; 2013515ad66cSMikulas Patocka pe_to_start_last = pe; 2014515ad66cSMikulas Patocka } 2015b4b610f6SAlasdair G Kergon } 201676df1c65SAlasdair G Kergon 2017eccf0817SAlasdair G Kergon if (!pe->started) { 2018eccf0817SAlasdair G Kergon pe->started = 1; 2019515ad66cSMikulas Patocka pe_to_start_now = pe; 2020eccf0817SAlasdair G Kergon } 20211da177e4SLinus Torvalds 202276df1c65SAlasdair G Kergon next_snapshot: 20231da177e4SLinus Torvalds up_write(&snap->lock); 2024515ad66cSMikulas Patocka 2025515ad66cSMikulas Patocka if (pe_to_start_now) { 2026515ad66cSMikulas Patocka start_copy(pe_to_start_now); 2027515ad66cSMikulas Patocka pe_to_start_now = NULL; 20281da177e4SLinus Torvalds } 2029b4b610f6SAlasdair G Kergon } 2030b4b610f6SAlasdair G Kergon 20311da177e4SLinus Torvalds /* 2032515ad66cSMikulas Patocka * Submit the exception against which the bio is queued last, 2033515ad66cSMikulas Patocka * to give the other exceptions a head start. 20341da177e4SLinus Torvalds */ 2035515ad66cSMikulas Patocka if (pe_to_start_last) 2036515ad66cSMikulas Patocka start_copy(pe_to_start_last); 20371da177e4SLinus Torvalds 20381da177e4SLinus Torvalds return r; 20391da177e4SLinus Torvalds } 20401da177e4SLinus Torvalds 20411da177e4SLinus Torvalds /* 20421da177e4SLinus Torvalds * Called on a write from the origin driver. 20431da177e4SLinus Torvalds */ 20441da177e4SLinus Torvalds static int do_origin(struct dm_dev *origin, struct bio *bio) 20451da177e4SLinus Torvalds { 20461da177e4SLinus Torvalds struct origin *o; 2047d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED; 20481da177e4SLinus Torvalds 20491da177e4SLinus Torvalds down_read(&_origins_lock); 20501da177e4SLinus Torvalds o = __lookup_origin(origin->bdev); 20511da177e4SLinus Torvalds if (o) 20529eaae8ffSMikulas Patocka r = __origin_write(&o->snapshots, bio->bi_sector, bio); 20531da177e4SLinus Torvalds up_read(&_origins_lock); 20541da177e4SLinus Torvalds 20551da177e4SLinus Torvalds return r; 20561da177e4SLinus Torvalds } 20571da177e4SLinus Torvalds 20581da177e4SLinus Torvalds /* 205973dfd078SMikulas Patocka * Trigger exceptions in all non-merging snapshots. 206073dfd078SMikulas Patocka * 206173dfd078SMikulas Patocka * The chunk size of the merging snapshot may be larger than the chunk 206273dfd078SMikulas Patocka * size of some other snapshot so we may need to reallocate multiple 206373dfd078SMikulas Patocka * chunks in other snapshots. 206473dfd078SMikulas Patocka * 206573dfd078SMikulas Patocka * We scan all the overlapping exceptions in the other snapshots. 206673dfd078SMikulas Patocka * Returns 1 if anything was reallocated and must be waited for, 206773dfd078SMikulas Patocka * otherwise returns 0. 206873dfd078SMikulas Patocka * 206973dfd078SMikulas Patocka * size must be a multiple of merging_snap's chunk_size. 207073dfd078SMikulas Patocka */ 207173dfd078SMikulas Patocka static int origin_write_extent(struct dm_snapshot *merging_snap, 207273dfd078SMikulas Patocka sector_t sector, unsigned size) 207373dfd078SMikulas Patocka { 207473dfd078SMikulas Patocka int must_wait = 0; 207573dfd078SMikulas Patocka sector_t n; 207673dfd078SMikulas Patocka struct origin *o; 207773dfd078SMikulas Patocka 207873dfd078SMikulas Patocka /* 2079542f9038SMike Snitzer * The origin's __minimum_chunk_size() got stored in max_io_len 208073dfd078SMikulas Patocka * by snapshot_merge_resume(). 208173dfd078SMikulas Patocka */ 208273dfd078SMikulas Patocka down_read(&_origins_lock); 208373dfd078SMikulas Patocka o = __lookup_origin(merging_snap->origin->bdev); 2084542f9038SMike Snitzer for (n = 0; n < size; n += merging_snap->ti->max_io_len) 208573dfd078SMikulas Patocka if (__origin_write(&o->snapshots, sector + n, NULL) == 208673dfd078SMikulas Patocka DM_MAPIO_SUBMITTED) 208773dfd078SMikulas Patocka must_wait = 1; 208873dfd078SMikulas Patocka up_read(&_origins_lock); 208973dfd078SMikulas Patocka 209073dfd078SMikulas Patocka return must_wait; 209173dfd078SMikulas Patocka } 209273dfd078SMikulas Patocka 209373dfd078SMikulas Patocka /* 20941da177e4SLinus Torvalds * Origin: maps a linear range of a device, with hooks for snapshotting. 20951da177e4SLinus Torvalds */ 20961da177e4SLinus Torvalds 20971da177e4SLinus Torvalds /* 20981da177e4SLinus Torvalds * Construct an origin mapping: <dev_path> 20991da177e4SLinus Torvalds * The context for an origin is merely a 'struct dm_dev *' 21001da177e4SLinus Torvalds * pointing to the real device. 21011da177e4SLinus Torvalds */ 21021da177e4SLinus Torvalds static int origin_ctr(struct dm_target *ti, unsigned int argc, char **argv) 21031da177e4SLinus Torvalds { 21041da177e4SLinus Torvalds int r; 21051da177e4SLinus Torvalds struct dm_dev *dev; 21061da177e4SLinus Torvalds 21071da177e4SLinus Torvalds if (argc != 1) { 210872d94861SAlasdair G Kergon ti->error = "origin: incorrect number of arguments"; 21091da177e4SLinus Torvalds return -EINVAL; 21101da177e4SLinus Torvalds } 21111da177e4SLinus Torvalds 21128215d6ecSNikanth Karthikesan r = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &dev); 21131da177e4SLinus Torvalds if (r) { 21141da177e4SLinus Torvalds ti->error = "Cannot get target device"; 21151da177e4SLinus Torvalds return r; 21161da177e4SLinus Torvalds } 21171da177e4SLinus Torvalds 21181da177e4SLinus Torvalds ti->private = dev; 2119494b3ee7SMikulas Patocka ti->num_flush_requests = 1; 2120494b3ee7SMikulas Patocka 21211da177e4SLinus Torvalds return 0; 21221da177e4SLinus Torvalds } 21231da177e4SLinus Torvalds 21241da177e4SLinus Torvalds static void origin_dtr(struct dm_target *ti) 21251da177e4SLinus Torvalds { 2126028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 21271da177e4SLinus Torvalds dm_put_device(ti, dev); 21281da177e4SLinus Torvalds } 21291da177e4SLinus Torvalds 21301da177e4SLinus Torvalds static int origin_map(struct dm_target *ti, struct bio *bio, 21311da177e4SLinus Torvalds union map_info *map_context) 21321da177e4SLinus Torvalds { 2133028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 21341da177e4SLinus Torvalds bio->bi_bdev = dev->bdev; 21351da177e4SLinus Torvalds 2136d87f4c14STejun Heo if (bio->bi_rw & REQ_FLUSH) 2137494b3ee7SMikulas Patocka return DM_MAPIO_REMAPPED; 2138494b3ee7SMikulas Patocka 21391da177e4SLinus Torvalds /* Only tell snapshots if this is a write */ 2140d2a7ad29SKiyoshi Ueda return (bio_rw(bio) == WRITE) ? do_origin(dev, bio) : DM_MAPIO_REMAPPED; 21411da177e4SLinus Torvalds } 21421da177e4SLinus Torvalds 21431da177e4SLinus Torvalds /* 2144542f9038SMike Snitzer * Set the target "max_io_len" field to the minimum of all the snapshots' 21451da177e4SLinus Torvalds * chunk sizes. 21461da177e4SLinus Torvalds */ 21471da177e4SLinus Torvalds static void origin_resume(struct dm_target *ti) 21481da177e4SLinus Torvalds { 2149028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 21501da177e4SLinus Torvalds 2151542f9038SMike Snitzer ti->max_io_len = get_origin_minimum_chunksize(dev->bdev); 21521da177e4SLinus Torvalds } 21531da177e4SLinus Torvalds 21541da177e4SLinus Torvalds static int origin_status(struct dm_target *ti, status_type_t type, char *result, 21551da177e4SLinus Torvalds unsigned int maxlen) 21561da177e4SLinus Torvalds { 2157028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 21581da177e4SLinus Torvalds 21591da177e4SLinus Torvalds switch (type) { 21601da177e4SLinus Torvalds case STATUSTYPE_INFO: 21611da177e4SLinus Torvalds result[0] = '\0'; 21621da177e4SLinus Torvalds break; 21631da177e4SLinus Torvalds 21641da177e4SLinus Torvalds case STATUSTYPE_TABLE: 21651da177e4SLinus Torvalds snprintf(result, maxlen, "%s", dev->name); 21661da177e4SLinus Torvalds break; 21671da177e4SLinus Torvalds } 21681da177e4SLinus Torvalds 21691da177e4SLinus Torvalds return 0; 21701da177e4SLinus Torvalds } 21711da177e4SLinus Torvalds 2172b1d55528SMikulas Patocka static int origin_merge(struct dm_target *ti, struct bvec_merge_data *bvm, 2173b1d55528SMikulas Patocka struct bio_vec *biovec, int max_size) 2174b1d55528SMikulas Patocka { 2175b1d55528SMikulas Patocka struct dm_dev *dev = ti->private; 2176b1d55528SMikulas Patocka struct request_queue *q = bdev_get_queue(dev->bdev); 2177b1d55528SMikulas Patocka 2178b1d55528SMikulas Patocka if (!q->merge_bvec_fn) 2179b1d55528SMikulas Patocka return max_size; 2180b1d55528SMikulas Patocka 2181b1d55528SMikulas Patocka bvm->bi_bdev = dev->bdev; 2182b1d55528SMikulas Patocka 2183b1d55528SMikulas Patocka return min(max_size, q->merge_bvec_fn(q, bvm, biovec)); 2184b1d55528SMikulas Patocka } 2185b1d55528SMikulas Patocka 21868811f46cSMike Snitzer static int origin_iterate_devices(struct dm_target *ti, 21878811f46cSMike Snitzer iterate_devices_callout_fn fn, void *data) 21888811f46cSMike Snitzer { 21898811f46cSMike Snitzer struct dm_dev *dev = ti->private; 21908811f46cSMike Snitzer 21918811f46cSMike Snitzer return fn(ti, dev, 0, ti->len, data); 21928811f46cSMike Snitzer } 21938811f46cSMike Snitzer 21941da177e4SLinus Torvalds static struct target_type origin_target = { 21951da177e4SLinus Torvalds .name = "snapshot-origin", 2196b83b2f29SMike Snitzer .version = {1, 7, 1}, 21971da177e4SLinus Torvalds .module = THIS_MODULE, 21981da177e4SLinus Torvalds .ctr = origin_ctr, 21991da177e4SLinus Torvalds .dtr = origin_dtr, 22001da177e4SLinus Torvalds .map = origin_map, 22011da177e4SLinus Torvalds .resume = origin_resume, 22021da177e4SLinus Torvalds .status = origin_status, 2203b1d55528SMikulas Patocka .merge = origin_merge, 22048811f46cSMike Snitzer .iterate_devices = origin_iterate_devices, 22051da177e4SLinus Torvalds }; 22061da177e4SLinus Torvalds 22071da177e4SLinus Torvalds static struct target_type snapshot_target = { 22081da177e4SLinus Torvalds .name = "snapshot", 2209b83b2f29SMike Snitzer .version = {1, 10, 0}, 22101da177e4SLinus Torvalds .module = THIS_MODULE, 22111da177e4SLinus Torvalds .ctr = snapshot_ctr, 22121da177e4SLinus Torvalds .dtr = snapshot_dtr, 22131da177e4SLinus Torvalds .map = snapshot_map, 2214cd45daffSMikulas Patocka .end_io = snapshot_end_io, 2215c1f0c183SMike Snitzer .preresume = snapshot_preresume, 22161da177e4SLinus Torvalds .resume = snapshot_resume, 22171da177e4SLinus Torvalds .status = snapshot_status, 22188811f46cSMike Snitzer .iterate_devices = snapshot_iterate_devices, 22191da177e4SLinus Torvalds }; 22201da177e4SLinus Torvalds 2221d698aa45SMikulas Patocka static struct target_type merge_target = { 2222d698aa45SMikulas Patocka .name = dm_snapshot_merge_target_name, 2223b83b2f29SMike Snitzer .version = {1, 1, 0}, 2224d698aa45SMikulas Patocka .module = THIS_MODULE, 2225d698aa45SMikulas Patocka .ctr = snapshot_ctr, 2226d698aa45SMikulas Patocka .dtr = snapshot_dtr, 22273452c2a1SMikulas Patocka .map = snapshot_merge_map, 2228d698aa45SMikulas Patocka .end_io = snapshot_end_io, 22291e03f97eSMikulas Patocka .presuspend = snapshot_merge_presuspend, 2230d698aa45SMikulas Patocka .preresume = snapshot_preresume, 22311e03f97eSMikulas Patocka .resume = snapshot_merge_resume, 2232d698aa45SMikulas Patocka .status = snapshot_status, 2233d698aa45SMikulas Patocka .iterate_devices = snapshot_iterate_devices, 2234d698aa45SMikulas Patocka }; 2235d698aa45SMikulas Patocka 22361da177e4SLinus Torvalds static int __init dm_snapshot_init(void) 22371da177e4SLinus Torvalds { 22381da177e4SLinus Torvalds int r; 22391da177e4SLinus Torvalds 22404db6bfe0SAlasdair G Kergon r = dm_exception_store_init(); 22414db6bfe0SAlasdair G Kergon if (r) { 22424db6bfe0SAlasdair G Kergon DMERR("Failed to initialize exception stores"); 22434db6bfe0SAlasdair G Kergon return r; 22444db6bfe0SAlasdair G Kergon } 22454db6bfe0SAlasdair G Kergon 22461da177e4SLinus Torvalds r = dm_register_target(&snapshot_target); 2247d698aa45SMikulas Patocka if (r < 0) { 22481da177e4SLinus Torvalds DMERR("snapshot target register failed %d", r); 2249034a186dSJonathan Brassow goto bad_register_snapshot_target; 22501da177e4SLinus Torvalds } 22511da177e4SLinus Torvalds 22521da177e4SLinus Torvalds r = dm_register_target(&origin_target); 22531da177e4SLinus Torvalds if (r < 0) { 225472d94861SAlasdair G Kergon DMERR("Origin target register failed %d", r); 2255d698aa45SMikulas Patocka goto bad_register_origin_target; 2256d698aa45SMikulas Patocka } 2257d698aa45SMikulas Patocka 2258d698aa45SMikulas Patocka r = dm_register_target(&merge_target); 2259d698aa45SMikulas Patocka if (r < 0) { 2260d698aa45SMikulas Patocka DMERR("Merge target register failed %d", r); 2261d698aa45SMikulas Patocka goto bad_register_merge_target; 22621da177e4SLinus Torvalds } 22631da177e4SLinus Torvalds 22641da177e4SLinus Torvalds r = init_origin_hash(); 22651da177e4SLinus Torvalds if (r) { 22661da177e4SLinus Torvalds DMERR("init_origin_hash failed."); 2267d698aa45SMikulas Patocka goto bad_origin_hash; 22681da177e4SLinus Torvalds } 22691da177e4SLinus Torvalds 22701d4989c8SJon Brassow exception_cache = KMEM_CACHE(dm_exception, 0); 22711da177e4SLinus Torvalds if (!exception_cache) { 22721da177e4SLinus Torvalds DMERR("Couldn't create exception cache."); 22731da177e4SLinus Torvalds r = -ENOMEM; 2274d698aa45SMikulas Patocka goto bad_exception_cache; 22751da177e4SLinus Torvalds } 22761da177e4SLinus Torvalds 2277028867acSAlasdair G Kergon pending_cache = KMEM_CACHE(dm_snap_pending_exception, 0); 22781da177e4SLinus Torvalds if (!pending_cache) { 22791da177e4SLinus Torvalds DMERR("Couldn't create pending cache."); 22801da177e4SLinus Torvalds r = -ENOMEM; 2281d698aa45SMikulas Patocka goto bad_pending_cache; 22821da177e4SLinus Torvalds } 22831da177e4SLinus Torvalds 2284cd45daffSMikulas Patocka tracked_chunk_cache = KMEM_CACHE(dm_snap_tracked_chunk, 0); 2285cd45daffSMikulas Patocka if (!tracked_chunk_cache) { 2286cd45daffSMikulas Patocka DMERR("Couldn't create cache to track chunks in use."); 2287cd45daffSMikulas Patocka r = -ENOMEM; 2288d698aa45SMikulas Patocka goto bad_tracked_chunk_cache; 2289cd45daffSMikulas Patocka } 2290cd45daffSMikulas Patocka 22911da177e4SLinus Torvalds return 0; 22921da177e4SLinus Torvalds 2293d698aa45SMikulas Patocka bad_tracked_chunk_cache: 22941da177e4SLinus Torvalds kmem_cache_destroy(pending_cache); 2295d698aa45SMikulas Patocka bad_pending_cache: 22961da177e4SLinus Torvalds kmem_cache_destroy(exception_cache); 2297d698aa45SMikulas Patocka bad_exception_cache: 22981da177e4SLinus Torvalds exit_origin_hash(); 2299d698aa45SMikulas Patocka bad_origin_hash: 2300d698aa45SMikulas Patocka dm_unregister_target(&merge_target); 2301d698aa45SMikulas Patocka bad_register_merge_target: 23021da177e4SLinus Torvalds dm_unregister_target(&origin_target); 2303d698aa45SMikulas Patocka bad_register_origin_target: 23041da177e4SLinus Torvalds dm_unregister_target(&snapshot_target); 2305034a186dSJonathan Brassow bad_register_snapshot_target: 2306034a186dSJonathan Brassow dm_exception_store_exit(); 2307d698aa45SMikulas Patocka 23081da177e4SLinus Torvalds return r; 23091da177e4SLinus Torvalds } 23101da177e4SLinus Torvalds 23111da177e4SLinus Torvalds static void __exit dm_snapshot_exit(void) 23121da177e4SLinus Torvalds { 231310d3bd09SMikulas Patocka dm_unregister_target(&snapshot_target); 231410d3bd09SMikulas Patocka dm_unregister_target(&origin_target); 2315d698aa45SMikulas Patocka dm_unregister_target(&merge_target); 23161da177e4SLinus Torvalds 23171da177e4SLinus Torvalds exit_origin_hash(); 23181da177e4SLinus Torvalds kmem_cache_destroy(pending_cache); 23191da177e4SLinus Torvalds kmem_cache_destroy(exception_cache); 2320cd45daffSMikulas Patocka kmem_cache_destroy(tracked_chunk_cache); 23214db6bfe0SAlasdair G Kergon 23224db6bfe0SAlasdair G Kergon dm_exception_store_exit(); 23231da177e4SLinus Torvalds } 23241da177e4SLinus Torvalds 23251da177e4SLinus Torvalds /* Module hooks */ 23261da177e4SLinus Torvalds module_init(dm_snapshot_init); 23271da177e4SLinus Torvalds module_exit(dm_snapshot_exit); 23281da177e4SLinus Torvalds 23291da177e4SLinus Torvalds MODULE_DESCRIPTION(DM_NAME " snapshot target"); 23301da177e4SLinus Torvalds MODULE_AUTHOR("Joe Thornber"); 23311da177e4SLinus Torvalds MODULE_LICENSE("GPL"); 2332