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> 22ccc45ea8SJonathan Brassow #include <linux/workqueue.h> 231da177e4SLinus Torvalds 24aea53d92SJonathan Brassow #include "dm-exception-store.h" 251da177e4SLinus Torvalds 2672d94861SAlasdair G Kergon #define DM_MSG_PREFIX "snapshots" 2772d94861SAlasdair G Kergon 28d698aa45SMikulas Patocka static const char dm_snapshot_merge_target_name[] = "snapshot-merge"; 29d698aa45SMikulas Patocka 30d698aa45SMikulas Patocka #define dm_target_is_snapshot_merge(ti) \ 31d698aa45SMikulas Patocka ((ti)->type->name == dm_snapshot_merge_target_name) 32d698aa45SMikulas Patocka 331da177e4SLinus Torvalds /* 341da177e4SLinus Torvalds * The percentage increment we will wake up users at 351da177e4SLinus Torvalds */ 361da177e4SLinus Torvalds #define WAKE_UP_PERCENT 5 371da177e4SLinus Torvalds 381da177e4SLinus Torvalds /* 391da177e4SLinus Torvalds * kcopyd priority of snapshot operations 401da177e4SLinus Torvalds */ 411da177e4SLinus Torvalds #define SNAPSHOT_COPY_PRIORITY 2 421da177e4SLinus Torvalds 431da177e4SLinus Torvalds /* 448ee2767aSMilan Broz * Reserve 1MB for each snapshot initially (with minimum of 1 page). 451da177e4SLinus Torvalds */ 468ee2767aSMilan Broz #define SNAPSHOT_PAGES (((1UL << 20) >> PAGE_SHIFT) ? : 1) 471da177e4SLinus Torvalds 48cd45daffSMikulas Patocka /* 49cd45daffSMikulas Patocka * The size of the mempool used to track chunks in use. 50cd45daffSMikulas Patocka */ 51cd45daffSMikulas Patocka #define MIN_IOS 256 52cd45daffSMikulas Patocka 53ccc45ea8SJonathan Brassow #define DM_TRACKED_CHUNK_HASH_SIZE 16 54ccc45ea8SJonathan Brassow #define DM_TRACKED_CHUNK_HASH(x) ((unsigned long)(x) & \ 55ccc45ea8SJonathan Brassow (DM_TRACKED_CHUNK_HASH_SIZE - 1)) 56ccc45ea8SJonathan Brassow 57191437a5SJon Brassow struct dm_exception_table { 58ccc45ea8SJonathan Brassow uint32_t hash_mask; 59ccc45ea8SJonathan Brassow unsigned hash_shift; 60ccc45ea8SJonathan Brassow struct list_head *table; 61ccc45ea8SJonathan Brassow }; 62ccc45ea8SJonathan Brassow 63ccc45ea8SJonathan Brassow struct dm_snapshot { 64ccc45ea8SJonathan Brassow struct rw_semaphore lock; 65ccc45ea8SJonathan Brassow 66ccc45ea8SJonathan Brassow struct dm_dev *origin; 67fc56f6fbSMike Snitzer struct dm_dev *cow; 68fc56f6fbSMike Snitzer 69fc56f6fbSMike Snitzer struct dm_target *ti; 70ccc45ea8SJonathan Brassow 71ccc45ea8SJonathan Brassow /* List of snapshots per Origin */ 72ccc45ea8SJonathan Brassow struct list_head list; 73ccc45ea8SJonathan Brassow 74d8ddb1cfSMike Snitzer /* 75d8ddb1cfSMike Snitzer * You can't use a snapshot if this is 0 (e.g. if full). 76d8ddb1cfSMike Snitzer * A snapshot-merge target never clears this. 77d8ddb1cfSMike Snitzer */ 78ccc45ea8SJonathan Brassow int valid; 79ccc45ea8SJonathan Brassow 80ccc45ea8SJonathan Brassow /* Origin writes don't trigger exceptions until this is set */ 81ccc45ea8SJonathan Brassow int active; 82ccc45ea8SJonathan Brassow 83c26655caSMike Snitzer /* Whether or not owning mapped_device is suspended */ 84c26655caSMike Snitzer int suspended; 85c26655caSMike Snitzer 86ccc45ea8SJonathan Brassow mempool_t *pending_pool; 87ccc45ea8SJonathan Brassow 88ccc45ea8SJonathan Brassow atomic_t pending_exceptions_count; 89ccc45ea8SJonathan Brassow 90191437a5SJon Brassow struct dm_exception_table pending; 91191437a5SJon Brassow struct dm_exception_table complete; 92ccc45ea8SJonathan Brassow 93ccc45ea8SJonathan Brassow /* 94ccc45ea8SJonathan Brassow * pe_lock protects all pending_exception operations and access 95ccc45ea8SJonathan Brassow * as well as the snapshot_bios list. 96ccc45ea8SJonathan Brassow */ 97ccc45ea8SJonathan Brassow spinlock_t pe_lock; 98ccc45ea8SJonathan Brassow 99ccc45ea8SJonathan Brassow /* The on disk metadata handler */ 100ccc45ea8SJonathan Brassow struct dm_exception_store *store; 101ccc45ea8SJonathan Brassow 102ccc45ea8SJonathan Brassow struct dm_kcopyd_client *kcopyd_client; 103ccc45ea8SJonathan Brassow 104ccc45ea8SJonathan Brassow /* Queue of snapshot writes for ksnapd to flush */ 105ccc45ea8SJonathan Brassow struct bio_list queued_bios; 106ccc45ea8SJonathan Brassow struct work_struct queued_bios_work; 107ccc45ea8SJonathan Brassow 108ccc45ea8SJonathan Brassow /* Chunks with outstanding reads */ 109ccc45ea8SJonathan Brassow mempool_t *tracked_chunk_pool; 110ccc45ea8SJonathan Brassow spinlock_t tracked_chunk_lock; 111ccc45ea8SJonathan Brassow struct hlist_head tracked_chunk_hash[DM_TRACKED_CHUNK_HASH_SIZE]; 1121e03f97eSMikulas Patocka 113d8ddb1cfSMike Snitzer /* 114d8ddb1cfSMike Snitzer * The merge operation failed if this flag is set. 115d8ddb1cfSMike Snitzer * Failure modes are handled as follows: 116d8ddb1cfSMike Snitzer * - I/O error reading the header 117d8ddb1cfSMike Snitzer * => don't load the target; abort. 118d8ddb1cfSMike Snitzer * - Header does not have "valid" flag set 119d8ddb1cfSMike Snitzer * => use the origin; forget about the snapshot. 120d8ddb1cfSMike Snitzer * - I/O error when reading exceptions 121d8ddb1cfSMike Snitzer * => don't load the target; abort. 122d8ddb1cfSMike Snitzer * (We can't use the intermediate origin state.) 123d8ddb1cfSMike Snitzer * - I/O error while merging 124d8ddb1cfSMike Snitzer * => stop merging; set merge_failed; process I/O normally. 125d8ddb1cfSMike Snitzer */ 126d8ddb1cfSMike Snitzer int merge_failed; 127d8ddb1cfSMike Snitzer 1281e03f97eSMikulas Patocka /* Wait for events based on state_bits */ 1291e03f97eSMikulas Patocka unsigned long state_bits; 1309fe86254SMikulas Patocka 1319fe86254SMikulas Patocka /* Range of chunks currently being merged. */ 1329fe86254SMikulas Patocka chunk_t first_merging_chunk; 1339fe86254SMikulas Patocka int num_merging_chunks; 1349fe86254SMikulas Patocka 1359fe86254SMikulas Patocka /* 1369fe86254SMikulas Patocka * Incoming bios that overlap with chunks being merged must wait 1379fe86254SMikulas Patocka * for them to be committed. 1389fe86254SMikulas Patocka */ 1399fe86254SMikulas Patocka struct bio_list bios_queued_during_merge; 140ccc45ea8SJonathan Brassow }; 141ccc45ea8SJonathan Brassow 1421e03f97eSMikulas Patocka /* 1431e03f97eSMikulas Patocka * state_bits: 1441e03f97eSMikulas Patocka * RUNNING_MERGE - Merge operation is in progress. 1451e03f97eSMikulas Patocka * SHUTDOWN_MERGE - Set to signal that merge needs to be stopped; 1461e03f97eSMikulas Patocka * cleared afterwards. 1471e03f97eSMikulas Patocka */ 1481e03f97eSMikulas Patocka #define RUNNING_MERGE 0 1491e03f97eSMikulas Patocka #define SHUTDOWN_MERGE 1 1501e03f97eSMikulas Patocka 151fc56f6fbSMike Snitzer struct dm_dev *dm_snap_cow(struct dm_snapshot *s) 152fc56f6fbSMike Snitzer { 153fc56f6fbSMike Snitzer return s->cow; 154fc56f6fbSMike Snitzer } 155fc56f6fbSMike Snitzer EXPORT_SYMBOL(dm_snap_cow); 156fc56f6fbSMike Snitzer 157c642f9e0SAdrian Bunk static struct workqueue_struct *ksnapd; 158c4028958SDavid Howells static void flush_queued_bios(struct work_struct *work); 159ca3a931fSAlasdair G Kergon 160ccc45ea8SJonathan Brassow static sector_t chunk_to_sector(struct dm_exception_store *store, 161ccc45ea8SJonathan Brassow chunk_t chunk) 162ccc45ea8SJonathan Brassow { 163ccc45ea8SJonathan Brassow return chunk << store->chunk_shift; 164ccc45ea8SJonathan Brassow } 165ccc45ea8SJonathan Brassow 166ccc45ea8SJonathan Brassow static int bdev_equal(struct block_device *lhs, struct block_device *rhs) 167ccc45ea8SJonathan Brassow { 168ccc45ea8SJonathan Brassow /* 169ccc45ea8SJonathan Brassow * There is only ever one instance of a particular block 170ccc45ea8SJonathan Brassow * device so we can compare pointers safely. 171ccc45ea8SJonathan Brassow */ 172ccc45ea8SJonathan Brassow return lhs == rhs; 173ccc45ea8SJonathan Brassow } 174ccc45ea8SJonathan Brassow 175028867acSAlasdair G Kergon struct dm_snap_pending_exception { 1761d4989c8SJon Brassow struct dm_exception e; 1771da177e4SLinus Torvalds 1781da177e4SLinus Torvalds /* 1791da177e4SLinus Torvalds * Origin buffers waiting for this to complete are held 1801da177e4SLinus Torvalds * in a bio list 1811da177e4SLinus Torvalds */ 1821da177e4SLinus Torvalds struct bio_list origin_bios; 1831da177e4SLinus Torvalds struct bio_list snapshot_bios; 1841da177e4SLinus Torvalds 1851da177e4SLinus Torvalds /* Pointer back to snapshot context */ 1861da177e4SLinus Torvalds struct dm_snapshot *snap; 1871da177e4SLinus Torvalds 1881da177e4SLinus Torvalds /* 1891da177e4SLinus Torvalds * 1 indicates the exception has already been sent to 1901da177e4SLinus Torvalds * kcopyd. 1911da177e4SLinus Torvalds */ 1921da177e4SLinus Torvalds int started; 1931da177e4SLinus Torvalds }; 1941da177e4SLinus Torvalds 1951da177e4SLinus Torvalds /* 1961da177e4SLinus Torvalds * Hash table mapping origin volumes to lists of snapshots and 1971da177e4SLinus Torvalds * a lock to protect it 1981da177e4SLinus Torvalds */ 199e18b890bSChristoph Lameter static struct kmem_cache *exception_cache; 200e18b890bSChristoph Lameter static struct kmem_cache *pending_cache; 2011da177e4SLinus Torvalds 202cd45daffSMikulas Patocka struct dm_snap_tracked_chunk { 203cd45daffSMikulas Patocka struct hlist_node node; 204cd45daffSMikulas Patocka chunk_t chunk; 205cd45daffSMikulas Patocka }; 206cd45daffSMikulas Patocka 207cd45daffSMikulas Patocka static struct kmem_cache *tracked_chunk_cache; 208cd45daffSMikulas Patocka 209cd45daffSMikulas Patocka static struct dm_snap_tracked_chunk *track_chunk(struct dm_snapshot *s, 210cd45daffSMikulas Patocka chunk_t chunk) 211cd45daffSMikulas Patocka { 212cd45daffSMikulas Patocka struct dm_snap_tracked_chunk *c = mempool_alloc(s->tracked_chunk_pool, 213cd45daffSMikulas Patocka GFP_NOIO); 214cd45daffSMikulas Patocka unsigned long flags; 215cd45daffSMikulas Patocka 216cd45daffSMikulas Patocka c->chunk = chunk; 217cd45daffSMikulas Patocka 218cd45daffSMikulas Patocka spin_lock_irqsave(&s->tracked_chunk_lock, flags); 219cd45daffSMikulas Patocka hlist_add_head(&c->node, 220cd45daffSMikulas Patocka &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)]); 221cd45daffSMikulas Patocka spin_unlock_irqrestore(&s->tracked_chunk_lock, flags); 222cd45daffSMikulas Patocka 223cd45daffSMikulas Patocka return c; 224cd45daffSMikulas Patocka } 225cd45daffSMikulas Patocka 226cd45daffSMikulas Patocka static void stop_tracking_chunk(struct dm_snapshot *s, 227cd45daffSMikulas Patocka struct dm_snap_tracked_chunk *c) 228cd45daffSMikulas Patocka { 229cd45daffSMikulas Patocka unsigned long flags; 230cd45daffSMikulas Patocka 231cd45daffSMikulas Patocka spin_lock_irqsave(&s->tracked_chunk_lock, flags); 232cd45daffSMikulas Patocka hlist_del(&c->node); 233cd45daffSMikulas Patocka spin_unlock_irqrestore(&s->tracked_chunk_lock, flags); 234cd45daffSMikulas Patocka 235cd45daffSMikulas Patocka mempool_free(c, s->tracked_chunk_pool); 236cd45daffSMikulas Patocka } 237cd45daffSMikulas Patocka 238a8d41b59SMikulas Patocka static int __chunk_is_tracked(struct dm_snapshot *s, chunk_t chunk) 239a8d41b59SMikulas Patocka { 240a8d41b59SMikulas Patocka struct dm_snap_tracked_chunk *c; 241a8d41b59SMikulas Patocka struct hlist_node *hn; 242a8d41b59SMikulas Patocka int found = 0; 243a8d41b59SMikulas Patocka 244a8d41b59SMikulas Patocka spin_lock_irq(&s->tracked_chunk_lock); 245a8d41b59SMikulas Patocka 246a8d41b59SMikulas Patocka hlist_for_each_entry(c, hn, 247a8d41b59SMikulas Patocka &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)], node) { 248a8d41b59SMikulas Patocka if (c->chunk == chunk) { 249a8d41b59SMikulas Patocka found = 1; 250a8d41b59SMikulas Patocka break; 251a8d41b59SMikulas Patocka } 252a8d41b59SMikulas Patocka } 253a8d41b59SMikulas Patocka 254a8d41b59SMikulas Patocka spin_unlock_irq(&s->tracked_chunk_lock); 255a8d41b59SMikulas Patocka 256a8d41b59SMikulas Patocka return found; 257a8d41b59SMikulas Patocka } 258a8d41b59SMikulas Patocka 2591da177e4SLinus Torvalds /* 260615d1eb9SMike Snitzer * This conflicting I/O is extremely improbable in the caller, 261615d1eb9SMike Snitzer * so msleep(1) is sufficient and there is no need for a wait queue. 262615d1eb9SMike Snitzer */ 263615d1eb9SMike Snitzer static void __check_for_conflicting_io(struct dm_snapshot *s, chunk_t chunk) 264615d1eb9SMike Snitzer { 265615d1eb9SMike Snitzer while (__chunk_is_tracked(s, chunk)) 266615d1eb9SMike Snitzer msleep(1); 267615d1eb9SMike Snitzer } 268615d1eb9SMike Snitzer 269615d1eb9SMike Snitzer /* 2701da177e4SLinus Torvalds * One of these per registered origin, held in the snapshot_origins hash 2711da177e4SLinus Torvalds */ 2721da177e4SLinus Torvalds struct origin { 2731da177e4SLinus Torvalds /* The origin device */ 2741da177e4SLinus Torvalds struct block_device *bdev; 2751da177e4SLinus Torvalds 2761da177e4SLinus Torvalds struct list_head hash_list; 2771da177e4SLinus Torvalds 2781da177e4SLinus Torvalds /* List of snapshots for this origin */ 2791da177e4SLinus Torvalds struct list_head snapshots; 2801da177e4SLinus Torvalds }; 2811da177e4SLinus Torvalds 2821da177e4SLinus Torvalds /* 2831da177e4SLinus Torvalds * Size of the hash table for origin volumes. If we make this 2841da177e4SLinus Torvalds * the size of the minors list then it should be nearly perfect 2851da177e4SLinus Torvalds */ 2861da177e4SLinus Torvalds #define ORIGIN_HASH_SIZE 256 2871da177e4SLinus Torvalds #define ORIGIN_MASK 0xFF 2881da177e4SLinus Torvalds static struct list_head *_origins; 2891da177e4SLinus Torvalds static struct rw_semaphore _origins_lock; 2901da177e4SLinus Torvalds 29173dfd078SMikulas Patocka static DECLARE_WAIT_QUEUE_HEAD(_pending_exceptions_done); 29273dfd078SMikulas Patocka static DEFINE_SPINLOCK(_pending_exceptions_done_spinlock); 29373dfd078SMikulas Patocka static uint64_t _pending_exceptions_done_count; 29473dfd078SMikulas Patocka 2951da177e4SLinus Torvalds static int init_origin_hash(void) 2961da177e4SLinus Torvalds { 2971da177e4SLinus Torvalds int i; 2981da177e4SLinus Torvalds 2991da177e4SLinus Torvalds _origins = kmalloc(ORIGIN_HASH_SIZE * sizeof(struct list_head), 3001da177e4SLinus Torvalds GFP_KERNEL); 3011da177e4SLinus Torvalds if (!_origins) { 30272d94861SAlasdair G Kergon DMERR("unable to allocate memory"); 3031da177e4SLinus Torvalds return -ENOMEM; 3041da177e4SLinus Torvalds } 3051da177e4SLinus Torvalds 3061da177e4SLinus Torvalds for (i = 0; i < ORIGIN_HASH_SIZE; i++) 3071da177e4SLinus Torvalds INIT_LIST_HEAD(_origins + i); 3081da177e4SLinus Torvalds init_rwsem(&_origins_lock); 3091da177e4SLinus Torvalds 3101da177e4SLinus Torvalds return 0; 3111da177e4SLinus Torvalds } 3121da177e4SLinus Torvalds 3131da177e4SLinus Torvalds static void exit_origin_hash(void) 3141da177e4SLinus Torvalds { 3151da177e4SLinus Torvalds kfree(_origins); 3161da177e4SLinus Torvalds } 3171da177e4SLinus Torvalds 318028867acSAlasdair G Kergon static unsigned origin_hash(struct block_device *bdev) 3191da177e4SLinus Torvalds { 3201da177e4SLinus Torvalds return bdev->bd_dev & ORIGIN_MASK; 3211da177e4SLinus Torvalds } 3221da177e4SLinus Torvalds 3231da177e4SLinus Torvalds static struct origin *__lookup_origin(struct block_device *origin) 3241da177e4SLinus Torvalds { 3251da177e4SLinus Torvalds struct list_head *ol; 3261da177e4SLinus Torvalds struct origin *o; 3271da177e4SLinus Torvalds 3281da177e4SLinus Torvalds ol = &_origins[origin_hash(origin)]; 3291da177e4SLinus Torvalds list_for_each_entry (o, ol, hash_list) 3301da177e4SLinus Torvalds if (bdev_equal(o->bdev, origin)) 3311da177e4SLinus Torvalds return o; 3321da177e4SLinus Torvalds 3331da177e4SLinus Torvalds return NULL; 3341da177e4SLinus Torvalds } 3351da177e4SLinus Torvalds 3361da177e4SLinus Torvalds static void __insert_origin(struct origin *o) 3371da177e4SLinus Torvalds { 3381da177e4SLinus Torvalds struct list_head *sl = &_origins[origin_hash(o->bdev)]; 3391da177e4SLinus Torvalds list_add_tail(&o->hash_list, sl); 3401da177e4SLinus Torvalds } 3411da177e4SLinus Torvalds 3421da177e4SLinus Torvalds /* 343c1f0c183SMike Snitzer * _origins_lock must be held when calling this function. 344c1f0c183SMike Snitzer * Returns number of snapshots registered using the supplied cow device, plus: 345c1f0c183SMike Snitzer * snap_src - a snapshot suitable for use as a source of exception handover 346c1f0c183SMike Snitzer * snap_dest - a snapshot capable of receiving exception handover. 3479d3b15c4SMikulas Patocka * snap_merge - an existing snapshot-merge target linked to the same origin. 3489d3b15c4SMikulas Patocka * There can be at most one snapshot-merge target. The parameter is optional. 349c1f0c183SMike Snitzer * 3509d3b15c4SMikulas Patocka * Possible return values and states of snap_src and snap_dest. 351c1f0c183SMike Snitzer * 0: NULL, NULL - first new snapshot 352c1f0c183SMike Snitzer * 1: snap_src, NULL - normal snapshot 353c1f0c183SMike Snitzer * 2: snap_src, snap_dest - waiting for handover 354c1f0c183SMike Snitzer * 2: snap_src, NULL - handed over, waiting for old to be deleted 355c1f0c183SMike Snitzer * 1: NULL, snap_dest - source got destroyed without handover 356c1f0c183SMike Snitzer */ 357c1f0c183SMike Snitzer static int __find_snapshots_sharing_cow(struct dm_snapshot *snap, 358c1f0c183SMike Snitzer struct dm_snapshot **snap_src, 3599d3b15c4SMikulas Patocka struct dm_snapshot **snap_dest, 3609d3b15c4SMikulas Patocka struct dm_snapshot **snap_merge) 361c1f0c183SMike Snitzer { 362c1f0c183SMike Snitzer struct dm_snapshot *s; 363c1f0c183SMike Snitzer struct origin *o; 364c1f0c183SMike Snitzer int count = 0; 365c1f0c183SMike Snitzer int active; 366c1f0c183SMike Snitzer 367c1f0c183SMike Snitzer o = __lookup_origin(snap->origin->bdev); 368c1f0c183SMike Snitzer if (!o) 369c1f0c183SMike Snitzer goto out; 370c1f0c183SMike Snitzer 371c1f0c183SMike Snitzer list_for_each_entry(s, &o->snapshots, list) { 3729d3b15c4SMikulas Patocka if (dm_target_is_snapshot_merge(s->ti) && snap_merge) 3739d3b15c4SMikulas Patocka *snap_merge = s; 374c1f0c183SMike Snitzer if (!bdev_equal(s->cow->bdev, snap->cow->bdev)) 375c1f0c183SMike Snitzer continue; 376c1f0c183SMike Snitzer 377c1f0c183SMike Snitzer down_read(&s->lock); 378c1f0c183SMike Snitzer active = s->active; 379c1f0c183SMike Snitzer up_read(&s->lock); 380c1f0c183SMike Snitzer 381c1f0c183SMike Snitzer if (active) { 382c1f0c183SMike Snitzer if (snap_src) 383c1f0c183SMike Snitzer *snap_src = s; 384c1f0c183SMike Snitzer } else if (snap_dest) 385c1f0c183SMike Snitzer *snap_dest = s; 386c1f0c183SMike Snitzer 387c1f0c183SMike Snitzer count++; 388c1f0c183SMike Snitzer } 389c1f0c183SMike Snitzer 390c1f0c183SMike Snitzer out: 391c1f0c183SMike Snitzer return count; 392c1f0c183SMike Snitzer } 393c1f0c183SMike Snitzer 394c1f0c183SMike Snitzer /* 395c1f0c183SMike Snitzer * On success, returns 1 if this snapshot is a handover destination, 396c1f0c183SMike Snitzer * otherwise returns 0. 397c1f0c183SMike Snitzer */ 398c1f0c183SMike Snitzer static int __validate_exception_handover(struct dm_snapshot *snap) 399c1f0c183SMike Snitzer { 400c1f0c183SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 4019d3b15c4SMikulas Patocka struct dm_snapshot *snap_merge = NULL; 402c1f0c183SMike Snitzer 403c1f0c183SMike Snitzer /* Does snapshot need exceptions handed over to it? */ 4049d3b15c4SMikulas Patocka if ((__find_snapshots_sharing_cow(snap, &snap_src, &snap_dest, 4059d3b15c4SMikulas Patocka &snap_merge) == 2) || 406c1f0c183SMike Snitzer snap_dest) { 407c1f0c183SMike Snitzer snap->ti->error = "Snapshot cow pairing for exception " 408c1f0c183SMike Snitzer "table handover failed"; 409c1f0c183SMike Snitzer return -EINVAL; 410c1f0c183SMike Snitzer } 411c1f0c183SMike Snitzer 412c1f0c183SMike Snitzer /* 413c1f0c183SMike Snitzer * If no snap_src was found, snap cannot become a handover 414c1f0c183SMike Snitzer * destination. 415c1f0c183SMike Snitzer */ 416c1f0c183SMike Snitzer if (!snap_src) 417c1f0c183SMike Snitzer return 0; 418c1f0c183SMike Snitzer 4199d3b15c4SMikulas Patocka /* 4209d3b15c4SMikulas Patocka * Non-snapshot-merge handover? 4219d3b15c4SMikulas Patocka */ 4229d3b15c4SMikulas Patocka if (!dm_target_is_snapshot_merge(snap->ti)) 4239d3b15c4SMikulas Patocka return 1; 4249d3b15c4SMikulas Patocka 4259d3b15c4SMikulas Patocka /* 4269d3b15c4SMikulas Patocka * Do not allow more than one merging snapshot. 4279d3b15c4SMikulas Patocka */ 4289d3b15c4SMikulas Patocka if (snap_merge) { 4299d3b15c4SMikulas Patocka snap->ti->error = "A snapshot is already merging."; 4309d3b15c4SMikulas Patocka return -EINVAL; 4319d3b15c4SMikulas Patocka } 4329d3b15c4SMikulas Patocka 4331e03f97eSMikulas Patocka if (!snap_src->store->type->prepare_merge || 4341e03f97eSMikulas Patocka !snap_src->store->type->commit_merge) { 4351e03f97eSMikulas Patocka snap->ti->error = "Snapshot exception store does not " 4361e03f97eSMikulas Patocka "support snapshot-merge."; 4371e03f97eSMikulas Patocka return -EINVAL; 4381e03f97eSMikulas Patocka } 4391e03f97eSMikulas Patocka 440c1f0c183SMike Snitzer return 1; 441c1f0c183SMike Snitzer } 442c1f0c183SMike Snitzer 443c1f0c183SMike Snitzer static void __insert_snapshot(struct origin *o, struct dm_snapshot *s) 444c1f0c183SMike Snitzer { 445c1f0c183SMike Snitzer struct dm_snapshot *l; 446c1f0c183SMike Snitzer 447c1f0c183SMike Snitzer /* Sort the list according to chunk size, largest-first smallest-last */ 448c1f0c183SMike Snitzer list_for_each_entry(l, &o->snapshots, list) 449c1f0c183SMike Snitzer if (l->store->chunk_size < s->store->chunk_size) 450c1f0c183SMike Snitzer break; 451c1f0c183SMike Snitzer list_add_tail(&s->list, &l->list); 452c1f0c183SMike Snitzer } 453c1f0c183SMike Snitzer 454c1f0c183SMike Snitzer /* 4551da177e4SLinus Torvalds * Make a note of the snapshot and its origin so we can look it 4561da177e4SLinus Torvalds * up when the origin has a write on it. 457c1f0c183SMike Snitzer * 458c1f0c183SMike Snitzer * Also validate snapshot exception store handovers. 459c1f0c183SMike Snitzer * On success, returns 1 if this registration is a handover destination, 460c1f0c183SMike Snitzer * otherwise returns 0. 4611da177e4SLinus Torvalds */ 4621da177e4SLinus Torvalds static int register_snapshot(struct dm_snapshot *snap) 4631da177e4SLinus Torvalds { 464c1f0c183SMike Snitzer struct origin *o, *new_o = NULL; 4651da177e4SLinus Torvalds struct block_device *bdev = snap->origin->bdev; 466c1f0c183SMike Snitzer int r = 0; 4671da177e4SLinus Torvalds 46860c856c8SMikulas Patocka new_o = kmalloc(sizeof(*new_o), GFP_KERNEL); 46960c856c8SMikulas Patocka if (!new_o) 47060c856c8SMikulas Patocka return -ENOMEM; 47160c856c8SMikulas Patocka 4721da177e4SLinus Torvalds down_write(&_origins_lock); 4731da177e4SLinus Torvalds 474c1f0c183SMike Snitzer r = __validate_exception_handover(snap); 475c1f0c183SMike Snitzer if (r < 0) { 476c1f0c183SMike Snitzer kfree(new_o); 477c1f0c183SMike Snitzer goto out; 478c1f0c183SMike Snitzer } 479c1f0c183SMike Snitzer 480c1f0c183SMike Snitzer o = __lookup_origin(bdev); 48160c856c8SMikulas Patocka if (o) 48260c856c8SMikulas Patocka kfree(new_o); 48360c856c8SMikulas Patocka else { 4841da177e4SLinus Torvalds /* New origin */ 48560c856c8SMikulas Patocka o = new_o; 4861da177e4SLinus Torvalds 4871da177e4SLinus Torvalds /* Initialise the struct */ 4881da177e4SLinus Torvalds INIT_LIST_HEAD(&o->snapshots); 4891da177e4SLinus Torvalds o->bdev = bdev; 4901da177e4SLinus Torvalds 4911da177e4SLinus Torvalds __insert_origin(o); 4921da177e4SLinus Torvalds } 4931da177e4SLinus Torvalds 494c1f0c183SMike Snitzer __insert_snapshot(o, snap); 495c1f0c183SMike Snitzer 496c1f0c183SMike Snitzer out: 497c1f0c183SMike Snitzer up_write(&_origins_lock); 498c1f0c183SMike Snitzer 499c1f0c183SMike Snitzer return r; 500c1f0c183SMike Snitzer } 501c1f0c183SMike Snitzer 502c1f0c183SMike Snitzer /* 503c1f0c183SMike Snitzer * Move snapshot to correct place in list according to chunk size. 504c1f0c183SMike Snitzer */ 505c1f0c183SMike Snitzer static void reregister_snapshot(struct dm_snapshot *s) 506c1f0c183SMike Snitzer { 507c1f0c183SMike Snitzer struct block_device *bdev = s->origin->bdev; 508c1f0c183SMike Snitzer 509c1f0c183SMike Snitzer down_write(&_origins_lock); 510c1f0c183SMike Snitzer 511c1f0c183SMike Snitzer list_del(&s->list); 512c1f0c183SMike Snitzer __insert_snapshot(__lookup_origin(bdev), s); 5131da177e4SLinus Torvalds 5141da177e4SLinus Torvalds up_write(&_origins_lock); 5151da177e4SLinus Torvalds } 5161da177e4SLinus Torvalds 5171da177e4SLinus Torvalds static void unregister_snapshot(struct dm_snapshot *s) 5181da177e4SLinus Torvalds { 5191da177e4SLinus Torvalds struct origin *o; 5201da177e4SLinus Torvalds 5211da177e4SLinus Torvalds down_write(&_origins_lock); 5221da177e4SLinus Torvalds o = __lookup_origin(s->origin->bdev); 5231da177e4SLinus Torvalds 5241da177e4SLinus Torvalds list_del(&s->list); 525c1f0c183SMike Snitzer if (o && list_empty(&o->snapshots)) { 5261da177e4SLinus Torvalds list_del(&o->hash_list); 5271da177e4SLinus Torvalds kfree(o); 5281da177e4SLinus Torvalds } 5291da177e4SLinus Torvalds 5301da177e4SLinus Torvalds up_write(&_origins_lock); 5311da177e4SLinus Torvalds } 5321da177e4SLinus Torvalds 5331da177e4SLinus Torvalds /* 5341da177e4SLinus Torvalds * Implementation of the exception hash tables. 535d74f81f8SMilan Broz * The lowest hash_shift bits of the chunk number are ignored, allowing 536d74f81f8SMilan Broz * some consecutive chunks to be grouped together. 5371da177e4SLinus Torvalds */ 5383510cb94SJon Brassow static int dm_exception_table_init(struct dm_exception_table *et, 5393510cb94SJon Brassow uint32_t size, unsigned hash_shift) 5401da177e4SLinus Torvalds { 5411da177e4SLinus Torvalds unsigned int i; 5421da177e4SLinus Torvalds 543d74f81f8SMilan Broz et->hash_shift = hash_shift; 5441da177e4SLinus Torvalds et->hash_mask = size - 1; 5451da177e4SLinus Torvalds et->table = dm_vcalloc(size, sizeof(struct list_head)); 5461da177e4SLinus Torvalds if (!et->table) 5471da177e4SLinus Torvalds return -ENOMEM; 5481da177e4SLinus Torvalds 5491da177e4SLinus Torvalds for (i = 0; i < size; i++) 5501da177e4SLinus Torvalds INIT_LIST_HEAD(et->table + i); 5511da177e4SLinus Torvalds 5521da177e4SLinus Torvalds return 0; 5531da177e4SLinus Torvalds } 5541da177e4SLinus Torvalds 5553510cb94SJon Brassow static void dm_exception_table_exit(struct dm_exception_table *et, 556191437a5SJon Brassow struct kmem_cache *mem) 5571da177e4SLinus Torvalds { 5581da177e4SLinus Torvalds struct list_head *slot; 5591d4989c8SJon Brassow struct dm_exception *ex, *next; 5601da177e4SLinus Torvalds int i, size; 5611da177e4SLinus Torvalds 5621da177e4SLinus Torvalds size = et->hash_mask + 1; 5631da177e4SLinus Torvalds for (i = 0; i < size; i++) { 5641da177e4SLinus Torvalds slot = et->table + i; 5651da177e4SLinus Torvalds 5661da177e4SLinus Torvalds list_for_each_entry_safe (ex, next, slot, hash_list) 5671da177e4SLinus Torvalds kmem_cache_free(mem, ex); 5681da177e4SLinus Torvalds } 5691da177e4SLinus Torvalds 5701da177e4SLinus Torvalds vfree(et->table); 5711da177e4SLinus Torvalds } 5721da177e4SLinus Torvalds 573191437a5SJon Brassow static uint32_t exception_hash(struct dm_exception_table *et, chunk_t chunk) 5741da177e4SLinus Torvalds { 575d74f81f8SMilan Broz return (chunk >> et->hash_shift) & et->hash_mask; 5761da177e4SLinus Torvalds } 5771da177e4SLinus Torvalds 5783510cb94SJon Brassow static void dm_remove_exception(struct dm_exception *e) 5791da177e4SLinus Torvalds { 5801da177e4SLinus Torvalds list_del(&e->hash_list); 5811da177e4SLinus Torvalds } 5821da177e4SLinus Torvalds 5831da177e4SLinus Torvalds /* 5841da177e4SLinus Torvalds * Return the exception data for a sector, or NULL if not 5851da177e4SLinus Torvalds * remapped. 5861da177e4SLinus Torvalds */ 5873510cb94SJon Brassow static struct dm_exception *dm_lookup_exception(struct dm_exception_table *et, 5881da177e4SLinus Torvalds chunk_t chunk) 5891da177e4SLinus Torvalds { 5901da177e4SLinus Torvalds struct list_head *slot; 5911d4989c8SJon Brassow struct dm_exception *e; 5921da177e4SLinus Torvalds 5931da177e4SLinus Torvalds slot = &et->table[exception_hash(et, chunk)]; 5941da177e4SLinus Torvalds list_for_each_entry (e, slot, hash_list) 595d74f81f8SMilan Broz if (chunk >= e->old_chunk && 596d74f81f8SMilan Broz chunk <= e->old_chunk + dm_consecutive_chunk_count(e)) 5971da177e4SLinus Torvalds return e; 5981da177e4SLinus Torvalds 5991da177e4SLinus Torvalds return NULL; 6001da177e4SLinus Torvalds } 6011da177e4SLinus Torvalds 6023510cb94SJon Brassow static struct dm_exception *alloc_completed_exception(void) 6031da177e4SLinus Torvalds { 6041d4989c8SJon Brassow struct dm_exception *e; 6051da177e4SLinus Torvalds 6061da177e4SLinus Torvalds e = kmem_cache_alloc(exception_cache, GFP_NOIO); 6071da177e4SLinus Torvalds if (!e) 6081da177e4SLinus Torvalds e = kmem_cache_alloc(exception_cache, GFP_ATOMIC); 6091da177e4SLinus Torvalds 6101da177e4SLinus Torvalds return e; 6111da177e4SLinus Torvalds } 6121da177e4SLinus Torvalds 6133510cb94SJon Brassow static void free_completed_exception(struct dm_exception *e) 6141da177e4SLinus Torvalds { 6151da177e4SLinus Torvalds kmem_cache_free(exception_cache, e); 6161da177e4SLinus Torvalds } 6171da177e4SLinus Torvalds 61892e86812SMikulas Patocka static struct dm_snap_pending_exception *alloc_pending_exception(struct dm_snapshot *s) 6191da177e4SLinus Torvalds { 62092e86812SMikulas Patocka struct dm_snap_pending_exception *pe = mempool_alloc(s->pending_pool, 62192e86812SMikulas Patocka GFP_NOIO); 62292e86812SMikulas Patocka 623879129d2SMikulas Patocka atomic_inc(&s->pending_exceptions_count); 62492e86812SMikulas Patocka pe->snap = s; 62592e86812SMikulas Patocka 62692e86812SMikulas Patocka return pe; 6271da177e4SLinus Torvalds } 6281da177e4SLinus Torvalds 629028867acSAlasdair G Kergon static void free_pending_exception(struct dm_snap_pending_exception *pe) 6301da177e4SLinus Torvalds { 631879129d2SMikulas Patocka struct dm_snapshot *s = pe->snap; 632879129d2SMikulas Patocka 633879129d2SMikulas Patocka mempool_free(pe, s->pending_pool); 634879129d2SMikulas Patocka smp_mb__before_atomic_dec(); 635879129d2SMikulas Patocka atomic_dec(&s->pending_exceptions_count); 6361da177e4SLinus Torvalds } 6371da177e4SLinus Torvalds 6383510cb94SJon Brassow static void dm_insert_exception(struct dm_exception_table *eh, 6391d4989c8SJon Brassow struct dm_exception *new_e) 640d74f81f8SMilan Broz { 641d74f81f8SMilan Broz struct list_head *l; 6421d4989c8SJon Brassow struct dm_exception *e = NULL; 643d74f81f8SMilan Broz 644d74f81f8SMilan Broz l = &eh->table[exception_hash(eh, new_e->old_chunk)]; 645d74f81f8SMilan Broz 646d74f81f8SMilan Broz /* Add immediately if this table doesn't support consecutive chunks */ 647d74f81f8SMilan Broz if (!eh->hash_shift) 648d74f81f8SMilan Broz goto out; 649d74f81f8SMilan Broz 650d74f81f8SMilan Broz /* List is ordered by old_chunk */ 651d74f81f8SMilan Broz list_for_each_entry_reverse(e, l, hash_list) { 652d74f81f8SMilan Broz /* Insert after an existing chunk? */ 653d74f81f8SMilan Broz if (new_e->old_chunk == (e->old_chunk + 654d74f81f8SMilan Broz dm_consecutive_chunk_count(e) + 1) && 655d74f81f8SMilan Broz new_e->new_chunk == (dm_chunk_number(e->new_chunk) + 656d74f81f8SMilan Broz dm_consecutive_chunk_count(e) + 1)) { 657d74f81f8SMilan Broz dm_consecutive_chunk_count_inc(e); 6583510cb94SJon Brassow free_completed_exception(new_e); 659d74f81f8SMilan Broz return; 660d74f81f8SMilan Broz } 661d74f81f8SMilan Broz 662d74f81f8SMilan Broz /* Insert before an existing chunk? */ 663d74f81f8SMilan Broz if (new_e->old_chunk == (e->old_chunk - 1) && 664d74f81f8SMilan Broz new_e->new_chunk == (dm_chunk_number(e->new_chunk) - 1)) { 665d74f81f8SMilan Broz dm_consecutive_chunk_count_inc(e); 666d74f81f8SMilan Broz e->old_chunk--; 667d74f81f8SMilan Broz e->new_chunk--; 6683510cb94SJon Brassow free_completed_exception(new_e); 669d74f81f8SMilan Broz return; 670d74f81f8SMilan Broz } 671d74f81f8SMilan Broz 672d74f81f8SMilan Broz if (new_e->old_chunk > e->old_chunk) 673d74f81f8SMilan Broz break; 674d74f81f8SMilan Broz } 675d74f81f8SMilan Broz 676d74f81f8SMilan Broz out: 677d74f81f8SMilan Broz list_add(&new_e->hash_list, e ? &e->hash_list : l); 678d74f81f8SMilan Broz } 679d74f81f8SMilan Broz 680a159c1acSJonathan Brassow /* 681a159c1acSJonathan Brassow * Callback used by the exception stores to load exceptions when 682a159c1acSJonathan Brassow * initialising. 683a159c1acSJonathan Brassow */ 684a159c1acSJonathan Brassow static int dm_add_exception(void *context, chunk_t old, chunk_t new) 6851da177e4SLinus Torvalds { 686a159c1acSJonathan Brassow struct dm_snapshot *s = context; 6871d4989c8SJon Brassow struct dm_exception *e; 6881da177e4SLinus Torvalds 6893510cb94SJon Brassow e = alloc_completed_exception(); 6901da177e4SLinus Torvalds if (!e) 6911da177e4SLinus Torvalds return -ENOMEM; 6921da177e4SLinus Torvalds 6931da177e4SLinus Torvalds e->old_chunk = old; 694d74f81f8SMilan Broz 695d74f81f8SMilan Broz /* Consecutive_count is implicitly initialised to zero */ 6961da177e4SLinus Torvalds e->new_chunk = new; 697d74f81f8SMilan Broz 6983510cb94SJon Brassow dm_insert_exception(&s->complete, e); 699d74f81f8SMilan Broz 7001da177e4SLinus Torvalds return 0; 7011da177e4SLinus Torvalds } 7021da177e4SLinus Torvalds 7037e201b35SMikulas Patocka #define min_not_zero(l, r) (((l) == 0) ? (r) : (((r) == 0) ? (l) : min(l, r))) 7047e201b35SMikulas Patocka 7057e201b35SMikulas Patocka /* 7067e201b35SMikulas Patocka * Return a minimum chunk size of all snapshots that have the specified origin. 7077e201b35SMikulas Patocka * Return zero if the origin has no snapshots. 7087e201b35SMikulas Patocka */ 7097e201b35SMikulas Patocka static sector_t __minimum_chunk_size(struct origin *o) 7107e201b35SMikulas Patocka { 7117e201b35SMikulas Patocka struct dm_snapshot *snap; 7127e201b35SMikulas Patocka unsigned chunk_size = 0; 7137e201b35SMikulas Patocka 7147e201b35SMikulas Patocka if (o) 7157e201b35SMikulas Patocka list_for_each_entry(snap, &o->snapshots, list) 7167e201b35SMikulas Patocka chunk_size = min_not_zero(chunk_size, 7177e201b35SMikulas Patocka snap->store->chunk_size); 7187e201b35SMikulas Patocka 7197e201b35SMikulas Patocka return chunk_size; 7207e201b35SMikulas Patocka } 7217e201b35SMikulas Patocka 7221da177e4SLinus Torvalds /* 7231da177e4SLinus Torvalds * Hard coded magic. 7241da177e4SLinus Torvalds */ 7251da177e4SLinus Torvalds static int calc_max_buckets(void) 7261da177e4SLinus Torvalds { 7271da177e4SLinus Torvalds /* use a fixed size of 2MB */ 7281da177e4SLinus Torvalds unsigned long mem = 2 * 1024 * 1024; 7291da177e4SLinus Torvalds mem /= sizeof(struct list_head); 7301da177e4SLinus Torvalds 7311da177e4SLinus Torvalds return mem; 7321da177e4SLinus Torvalds } 7331da177e4SLinus Torvalds 7341da177e4SLinus Torvalds /* 7351da177e4SLinus Torvalds * Allocate room for a suitable hash table. 7361da177e4SLinus Torvalds */ 737fee1998eSJonathan Brassow static int init_hash_tables(struct dm_snapshot *s) 7381da177e4SLinus Torvalds { 7391da177e4SLinus Torvalds sector_t hash_size, cow_dev_size, origin_dev_size, max_buckets; 7401da177e4SLinus Torvalds 7411da177e4SLinus Torvalds /* 7421da177e4SLinus Torvalds * Calculate based on the size of the original volume or 7431da177e4SLinus Torvalds * the COW volume... 7441da177e4SLinus Torvalds */ 745fc56f6fbSMike Snitzer cow_dev_size = get_dev_size(s->cow->bdev); 7461da177e4SLinus Torvalds origin_dev_size = get_dev_size(s->origin->bdev); 7471da177e4SLinus Torvalds max_buckets = calc_max_buckets(); 7481da177e4SLinus Torvalds 749fee1998eSJonathan Brassow hash_size = min(origin_dev_size, cow_dev_size) >> s->store->chunk_shift; 7501da177e4SLinus Torvalds hash_size = min(hash_size, max_buckets); 7511da177e4SLinus Torvalds 7528e87b9b8SMikulas Patocka if (hash_size < 64) 7538e87b9b8SMikulas Patocka hash_size = 64; 7548defd830SRobert P. J. Day hash_size = rounddown_pow_of_two(hash_size); 7553510cb94SJon Brassow if (dm_exception_table_init(&s->complete, hash_size, 756d74f81f8SMilan Broz DM_CHUNK_CONSECUTIVE_BITS)) 7571da177e4SLinus Torvalds return -ENOMEM; 7581da177e4SLinus Torvalds 7591da177e4SLinus Torvalds /* 7601da177e4SLinus Torvalds * Allocate hash table for in-flight exceptions 7611da177e4SLinus Torvalds * Make this smaller than the real hash table 7621da177e4SLinus Torvalds */ 7631da177e4SLinus Torvalds hash_size >>= 3; 7641da177e4SLinus Torvalds if (hash_size < 64) 7651da177e4SLinus Torvalds hash_size = 64; 7661da177e4SLinus Torvalds 7673510cb94SJon Brassow if (dm_exception_table_init(&s->pending, hash_size, 0)) { 7683510cb94SJon Brassow dm_exception_table_exit(&s->complete, exception_cache); 7691da177e4SLinus Torvalds return -ENOMEM; 7701da177e4SLinus Torvalds } 7711da177e4SLinus Torvalds 7721da177e4SLinus Torvalds return 0; 7731da177e4SLinus Torvalds } 7741da177e4SLinus Torvalds 7751e03f97eSMikulas Patocka static void merge_shutdown(struct dm_snapshot *s) 7761e03f97eSMikulas Patocka { 7771e03f97eSMikulas Patocka clear_bit_unlock(RUNNING_MERGE, &s->state_bits); 7781e03f97eSMikulas Patocka smp_mb__after_clear_bit(); 7791e03f97eSMikulas Patocka wake_up_bit(&s->state_bits, RUNNING_MERGE); 7801e03f97eSMikulas Patocka } 7811e03f97eSMikulas Patocka 7829fe86254SMikulas Patocka static struct bio *__release_queued_bios_after_merge(struct dm_snapshot *s) 7839fe86254SMikulas Patocka { 7849fe86254SMikulas Patocka s->first_merging_chunk = 0; 7859fe86254SMikulas Patocka s->num_merging_chunks = 0; 7869fe86254SMikulas Patocka 7879fe86254SMikulas Patocka return bio_list_get(&s->bios_queued_during_merge); 7889fe86254SMikulas Patocka } 7899fe86254SMikulas Patocka 7901e03f97eSMikulas Patocka /* 7911e03f97eSMikulas Patocka * Remove one chunk from the index of completed exceptions. 7921e03f97eSMikulas Patocka */ 7931e03f97eSMikulas Patocka static int __remove_single_exception_chunk(struct dm_snapshot *s, 7941e03f97eSMikulas Patocka chunk_t old_chunk) 7951e03f97eSMikulas Patocka { 7961e03f97eSMikulas Patocka struct dm_exception *e; 7971e03f97eSMikulas Patocka 7981e03f97eSMikulas Patocka e = dm_lookup_exception(&s->complete, old_chunk); 7991e03f97eSMikulas Patocka if (!e) { 8001e03f97eSMikulas Patocka DMERR("Corruption detected: exception for block %llu is " 8011e03f97eSMikulas Patocka "on disk but not in memory", 8021e03f97eSMikulas Patocka (unsigned long long)old_chunk); 8031e03f97eSMikulas Patocka return -EINVAL; 8041e03f97eSMikulas Patocka } 8051e03f97eSMikulas Patocka 8061e03f97eSMikulas Patocka /* 8071e03f97eSMikulas Patocka * If this is the only chunk using this exception, remove exception. 8081e03f97eSMikulas Patocka */ 8091e03f97eSMikulas Patocka if (!dm_consecutive_chunk_count(e)) { 8101e03f97eSMikulas Patocka dm_remove_exception(e); 8111e03f97eSMikulas Patocka free_completed_exception(e); 8121e03f97eSMikulas Patocka return 0; 8131e03f97eSMikulas Patocka } 8141e03f97eSMikulas Patocka 8151e03f97eSMikulas Patocka /* 8161e03f97eSMikulas Patocka * The chunk may be either at the beginning or the end of a 8171e03f97eSMikulas Patocka * group of consecutive chunks - never in the middle. We are 8181e03f97eSMikulas Patocka * removing chunks in the opposite order to that in which they 8191e03f97eSMikulas Patocka * were added, so this should always be true. 8201e03f97eSMikulas Patocka * Decrement the consecutive chunk counter and adjust the 8211e03f97eSMikulas Patocka * starting point if necessary. 8221e03f97eSMikulas Patocka */ 8231e03f97eSMikulas Patocka if (old_chunk == e->old_chunk) { 8241e03f97eSMikulas Patocka e->old_chunk++; 8251e03f97eSMikulas Patocka e->new_chunk++; 8261e03f97eSMikulas Patocka } else if (old_chunk != e->old_chunk + 8271e03f97eSMikulas Patocka dm_consecutive_chunk_count(e)) { 8281e03f97eSMikulas Patocka DMERR("Attempt to merge block %llu from the " 8291e03f97eSMikulas Patocka "middle of a chunk range [%llu - %llu]", 8301e03f97eSMikulas Patocka (unsigned long long)old_chunk, 8311e03f97eSMikulas Patocka (unsigned long long)e->old_chunk, 8321e03f97eSMikulas Patocka (unsigned long long) 8331e03f97eSMikulas Patocka e->old_chunk + dm_consecutive_chunk_count(e)); 8341e03f97eSMikulas Patocka return -EINVAL; 8351e03f97eSMikulas Patocka } 8361e03f97eSMikulas Patocka 8371e03f97eSMikulas Patocka dm_consecutive_chunk_count_dec(e); 8381e03f97eSMikulas Patocka 8391e03f97eSMikulas Patocka return 0; 8401e03f97eSMikulas Patocka } 8411e03f97eSMikulas Patocka 8429fe86254SMikulas Patocka static void flush_bios(struct bio *bio); 8439fe86254SMikulas Patocka 8449fe86254SMikulas Patocka static int remove_single_exception_chunk(struct dm_snapshot *s) 8451e03f97eSMikulas Patocka { 8469fe86254SMikulas Patocka struct bio *b = NULL; 8479fe86254SMikulas Patocka int r; 8489fe86254SMikulas Patocka chunk_t old_chunk = s->first_merging_chunk + s->num_merging_chunks - 1; 8491e03f97eSMikulas Patocka 8501e03f97eSMikulas Patocka down_write(&s->lock); 8519fe86254SMikulas Patocka 8529fe86254SMikulas Patocka /* 8539fe86254SMikulas Patocka * Process chunks (and associated exceptions) in reverse order 8549fe86254SMikulas Patocka * so that dm_consecutive_chunk_count_dec() accounting works. 8559fe86254SMikulas Patocka */ 8569fe86254SMikulas Patocka do { 8571e03f97eSMikulas Patocka r = __remove_single_exception_chunk(s, old_chunk); 8589fe86254SMikulas Patocka if (r) 8599fe86254SMikulas Patocka goto out; 8609fe86254SMikulas Patocka } while (old_chunk-- > s->first_merging_chunk); 8619fe86254SMikulas Patocka 8629fe86254SMikulas Patocka b = __release_queued_bios_after_merge(s); 8639fe86254SMikulas Patocka 8649fe86254SMikulas Patocka out: 8651e03f97eSMikulas Patocka up_write(&s->lock); 8669fe86254SMikulas Patocka if (b) 8679fe86254SMikulas Patocka flush_bios(b); 8681e03f97eSMikulas Patocka 8691e03f97eSMikulas Patocka return r; 8701e03f97eSMikulas Patocka } 8711e03f97eSMikulas Patocka 87273dfd078SMikulas Patocka static int origin_write_extent(struct dm_snapshot *merging_snap, 87373dfd078SMikulas Patocka sector_t sector, unsigned chunk_size); 87473dfd078SMikulas Patocka 8751e03f97eSMikulas Patocka static void merge_callback(int read_err, unsigned long write_err, 8761e03f97eSMikulas Patocka void *context); 8771e03f97eSMikulas Patocka 87873dfd078SMikulas Patocka static uint64_t read_pending_exceptions_done_count(void) 87973dfd078SMikulas Patocka { 88073dfd078SMikulas Patocka uint64_t pending_exceptions_done; 88173dfd078SMikulas Patocka 88273dfd078SMikulas Patocka spin_lock(&_pending_exceptions_done_spinlock); 88373dfd078SMikulas Patocka pending_exceptions_done = _pending_exceptions_done_count; 88473dfd078SMikulas Patocka spin_unlock(&_pending_exceptions_done_spinlock); 88573dfd078SMikulas Patocka 88673dfd078SMikulas Patocka return pending_exceptions_done; 88773dfd078SMikulas Patocka } 88873dfd078SMikulas Patocka 88973dfd078SMikulas Patocka static void increment_pending_exceptions_done_count(void) 89073dfd078SMikulas Patocka { 89173dfd078SMikulas Patocka spin_lock(&_pending_exceptions_done_spinlock); 89273dfd078SMikulas Patocka _pending_exceptions_done_count++; 89373dfd078SMikulas Patocka spin_unlock(&_pending_exceptions_done_spinlock); 89473dfd078SMikulas Patocka 89573dfd078SMikulas Patocka wake_up_all(&_pending_exceptions_done); 89673dfd078SMikulas Patocka } 89773dfd078SMikulas Patocka 8981e03f97eSMikulas Patocka static void snapshot_merge_next_chunks(struct dm_snapshot *s) 8991e03f97eSMikulas Patocka { 9008a2d5286SMike Snitzer int i, linear_chunks; 9011e03f97eSMikulas Patocka chunk_t old_chunk, new_chunk; 9021e03f97eSMikulas Patocka struct dm_io_region src, dest; 9038a2d5286SMike Snitzer sector_t io_size; 90473dfd078SMikulas Patocka uint64_t previous_count; 9051e03f97eSMikulas Patocka 9061e03f97eSMikulas Patocka BUG_ON(!test_bit(RUNNING_MERGE, &s->state_bits)); 9071e03f97eSMikulas Patocka if (unlikely(test_bit(SHUTDOWN_MERGE, &s->state_bits))) 9081e03f97eSMikulas Patocka goto shut; 9091e03f97eSMikulas Patocka 9101e03f97eSMikulas Patocka /* 9111e03f97eSMikulas Patocka * valid flag never changes during merge, so no lock required. 9121e03f97eSMikulas Patocka */ 9131e03f97eSMikulas Patocka if (!s->valid) { 9141e03f97eSMikulas Patocka DMERR("Snapshot is invalid: can't merge"); 9151e03f97eSMikulas Patocka goto shut; 9161e03f97eSMikulas Patocka } 9171e03f97eSMikulas Patocka 9188a2d5286SMike Snitzer linear_chunks = s->store->type->prepare_merge(s->store, &old_chunk, 9198a2d5286SMike Snitzer &new_chunk); 9208a2d5286SMike Snitzer if (linear_chunks <= 0) { 921d8ddb1cfSMike Snitzer if (linear_chunks < 0) { 9221e03f97eSMikulas Patocka DMERR("Read error in exception store: " 9231e03f97eSMikulas Patocka "shutting down merge"); 924d8ddb1cfSMike Snitzer down_write(&s->lock); 925d8ddb1cfSMike Snitzer s->merge_failed = 1; 926d8ddb1cfSMike Snitzer up_write(&s->lock); 927d8ddb1cfSMike Snitzer } 9281e03f97eSMikulas Patocka goto shut; 9291e03f97eSMikulas Patocka } 9301e03f97eSMikulas Patocka 9318a2d5286SMike Snitzer /* Adjust old_chunk and new_chunk to reflect start of linear region */ 9328a2d5286SMike Snitzer old_chunk = old_chunk + 1 - linear_chunks; 9338a2d5286SMike Snitzer new_chunk = new_chunk + 1 - linear_chunks; 9348a2d5286SMike Snitzer 9358a2d5286SMike Snitzer /* 9368a2d5286SMike Snitzer * Use one (potentially large) I/O to copy all 'linear_chunks' 9378a2d5286SMike Snitzer * from the exception store to the origin 9388a2d5286SMike Snitzer */ 9398a2d5286SMike Snitzer io_size = linear_chunks * s->store->chunk_size; 9401e03f97eSMikulas Patocka 9411e03f97eSMikulas Patocka dest.bdev = s->origin->bdev; 9421e03f97eSMikulas Patocka dest.sector = chunk_to_sector(s->store, old_chunk); 9438a2d5286SMike Snitzer dest.count = min(io_size, get_dev_size(dest.bdev) - dest.sector); 9441e03f97eSMikulas Patocka 9451e03f97eSMikulas Patocka src.bdev = s->cow->bdev; 9461e03f97eSMikulas Patocka src.sector = chunk_to_sector(s->store, new_chunk); 9471e03f97eSMikulas Patocka src.count = dest.count; 9481e03f97eSMikulas Patocka 94973dfd078SMikulas Patocka /* 95073dfd078SMikulas Patocka * Reallocate any exceptions needed in other snapshots then 95173dfd078SMikulas Patocka * wait for the pending exceptions to complete. 95273dfd078SMikulas Patocka * Each time any pending exception (globally on the system) 95373dfd078SMikulas Patocka * completes we are woken and repeat the process to find out 95473dfd078SMikulas Patocka * if we can proceed. While this may not seem a particularly 95573dfd078SMikulas Patocka * efficient algorithm, it is not expected to have any 95673dfd078SMikulas Patocka * significant impact on performance. 95773dfd078SMikulas Patocka */ 95873dfd078SMikulas Patocka previous_count = read_pending_exceptions_done_count(); 9598a2d5286SMike Snitzer while (origin_write_extent(s, dest.sector, io_size)) { 96073dfd078SMikulas Patocka wait_event(_pending_exceptions_done, 96173dfd078SMikulas Patocka (read_pending_exceptions_done_count() != 96273dfd078SMikulas Patocka previous_count)); 96373dfd078SMikulas Patocka /* Retry after the wait, until all exceptions are done. */ 96473dfd078SMikulas Patocka previous_count = read_pending_exceptions_done_count(); 96573dfd078SMikulas Patocka } 96673dfd078SMikulas Patocka 9679fe86254SMikulas Patocka down_write(&s->lock); 9689fe86254SMikulas Patocka s->first_merging_chunk = old_chunk; 9698a2d5286SMike Snitzer s->num_merging_chunks = linear_chunks; 9709fe86254SMikulas Patocka up_write(&s->lock); 9719fe86254SMikulas Patocka 9728a2d5286SMike Snitzer /* Wait until writes to all 'linear_chunks' drain */ 9738a2d5286SMike Snitzer for (i = 0; i < linear_chunks; i++) 9748a2d5286SMike Snitzer __check_for_conflicting_io(s, old_chunk + i); 9759fe86254SMikulas Patocka 9761e03f97eSMikulas Patocka dm_kcopyd_copy(s->kcopyd_client, &src, 1, &dest, 0, merge_callback, s); 9771e03f97eSMikulas Patocka return; 9781e03f97eSMikulas Patocka 9791e03f97eSMikulas Patocka shut: 9801e03f97eSMikulas Patocka merge_shutdown(s); 9811e03f97eSMikulas Patocka } 9821e03f97eSMikulas Patocka 9839fe86254SMikulas Patocka static void error_bios(struct bio *bio); 9849fe86254SMikulas Patocka 9851e03f97eSMikulas Patocka static void merge_callback(int read_err, unsigned long write_err, void *context) 9861e03f97eSMikulas Patocka { 9871e03f97eSMikulas Patocka struct dm_snapshot *s = context; 9889fe86254SMikulas Patocka struct bio *b = NULL; 9891e03f97eSMikulas Patocka 9901e03f97eSMikulas Patocka if (read_err || write_err) { 9911e03f97eSMikulas Patocka if (read_err) 9921e03f97eSMikulas Patocka DMERR("Read error: shutting down merge."); 9931e03f97eSMikulas Patocka else 9941e03f97eSMikulas Patocka DMERR("Write error: shutting down merge."); 9951e03f97eSMikulas Patocka goto shut; 9961e03f97eSMikulas Patocka } 9971e03f97eSMikulas Patocka 9989fe86254SMikulas Patocka if (s->store->type->commit_merge(s->store, 9999fe86254SMikulas Patocka s->num_merging_chunks) < 0) { 10001e03f97eSMikulas Patocka DMERR("Write error in exception store: shutting down merge"); 10011e03f97eSMikulas Patocka goto shut; 10021e03f97eSMikulas Patocka } 10031e03f97eSMikulas Patocka 10049fe86254SMikulas Patocka if (remove_single_exception_chunk(s) < 0) 10059fe86254SMikulas Patocka goto shut; 10069fe86254SMikulas Patocka 10071e03f97eSMikulas Patocka snapshot_merge_next_chunks(s); 10081e03f97eSMikulas Patocka 10091e03f97eSMikulas Patocka return; 10101e03f97eSMikulas Patocka 10111e03f97eSMikulas Patocka shut: 10129fe86254SMikulas Patocka down_write(&s->lock); 1013d8ddb1cfSMike Snitzer s->merge_failed = 1; 10149fe86254SMikulas Patocka b = __release_queued_bios_after_merge(s); 10159fe86254SMikulas Patocka up_write(&s->lock); 10169fe86254SMikulas Patocka error_bios(b); 10179fe86254SMikulas Patocka 10181e03f97eSMikulas Patocka merge_shutdown(s); 10191e03f97eSMikulas Patocka } 10201e03f97eSMikulas Patocka 10211e03f97eSMikulas Patocka static void start_merge(struct dm_snapshot *s) 10221e03f97eSMikulas Patocka { 10231e03f97eSMikulas Patocka if (!test_and_set_bit(RUNNING_MERGE, &s->state_bits)) 10241e03f97eSMikulas Patocka snapshot_merge_next_chunks(s); 10251e03f97eSMikulas Patocka } 10261e03f97eSMikulas Patocka 10271e03f97eSMikulas Patocka static int wait_schedule(void *ptr) 10281e03f97eSMikulas Patocka { 10291e03f97eSMikulas Patocka schedule(); 10301e03f97eSMikulas Patocka 10311e03f97eSMikulas Patocka return 0; 10321e03f97eSMikulas Patocka } 10331e03f97eSMikulas Patocka 10341e03f97eSMikulas Patocka /* 10351e03f97eSMikulas Patocka * Stop the merging process and wait until it finishes. 10361e03f97eSMikulas Patocka */ 10371e03f97eSMikulas Patocka static void stop_merge(struct dm_snapshot *s) 10381e03f97eSMikulas Patocka { 10391e03f97eSMikulas Patocka set_bit(SHUTDOWN_MERGE, &s->state_bits); 10401e03f97eSMikulas Patocka wait_on_bit(&s->state_bits, RUNNING_MERGE, wait_schedule, 10411e03f97eSMikulas Patocka TASK_UNINTERRUPTIBLE); 10421e03f97eSMikulas Patocka clear_bit(SHUTDOWN_MERGE, &s->state_bits); 10431e03f97eSMikulas Patocka } 10441e03f97eSMikulas Patocka 10451da177e4SLinus Torvalds /* 10461da177e4SLinus Torvalds * Construct a snapshot mapping: <origin_dev> <COW-dev> <p/n> <chunk-size> 10471da177e4SLinus Torvalds */ 10481da177e4SLinus Torvalds static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv) 10491da177e4SLinus Torvalds { 10501da177e4SLinus Torvalds struct dm_snapshot *s; 1051cd45daffSMikulas Patocka int i; 10521da177e4SLinus Torvalds int r = -EINVAL; 1053fc56f6fbSMike Snitzer char *origin_path, *cow_path; 105410b8106aSMike Snitzer unsigned args_used, num_flush_requests = 1; 105510b8106aSMike Snitzer fmode_t origin_mode = FMODE_READ; 10561da177e4SLinus Torvalds 10574c7e3bf4SMark McLoughlin if (argc != 4) { 105872d94861SAlasdair G Kergon ti->error = "requires exactly 4 arguments"; 10591da177e4SLinus Torvalds r = -EINVAL; 1060fc56f6fbSMike Snitzer goto bad; 10611da177e4SLinus Torvalds } 10621da177e4SLinus Torvalds 106310b8106aSMike Snitzer if (dm_target_is_snapshot_merge(ti)) { 106410b8106aSMike Snitzer num_flush_requests = 2; 106510b8106aSMike Snitzer origin_mode = FMODE_WRITE; 106610b8106aSMike Snitzer } 106710b8106aSMike Snitzer 10681da177e4SLinus Torvalds origin_path = argv[0]; 1069fee1998eSJonathan Brassow argv++; 1070fee1998eSJonathan Brassow argc--; 10711da177e4SLinus Torvalds 10721da177e4SLinus Torvalds s = kmalloc(sizeof(*s), GFP_KERNEL); 1073fee1998eSJonathan Brassow if (!s) { 10741da177e4SLinus Torvalds ti->error = "Cannot allocate snapshot context private " 10751da177e4SLinus Torvalds "structure"; 10761da177e4SLinus Torvalds r = -ENOMEM; 1077fc56f6fbSMike Snitzer goto bad; 10781da177e4SLinus Torvalds } 10791da177e4SLinus Torvalds 1080fc56f6fbSMike Snitzer cow_path = argv[0]; 1081fc56f6fbSMike Snitzer argv++; 1082fc56f6fbSMike Snitzer argc--; 1083fc56f6fbSMike Snitzer 1084fc56f6fbSMike Snitzer r = dm_get_device(ti, cow_path, 0, 0, 1085fc56f6fbSMike Snitzer FMODE_READ | FMODE_WRITE, &s->cow); 1086fc56f6fbSMike Snitzer if (r) { 1087fc56f6fbSMike Snitzer ti->error = "Cannot get COW device"; 1088fc56f6fbSMike Snitzer goto bad_cow; 1089fc56f6fbSMike Snitzer } 1090fc56f6fbSMike Snitzer 1091fc56f6fbSMike Snitzer r = dm_exception_store_create(ti, argc, argv, s, &args_used, &s->store); 1092fc56f6fbSMike Snitzer if (r) { 1093fc56f6fbSMike Snitzer ti->error = "Couldn't create exception store"; 1094fc56f6fbSMike Snitzer r = -EINVAL; 1095fc56f6fbSMike Snitzer goto bad_store; 1096fc56f6fbSMike Snitzer } 1097fc56f6fbSMike Snitzer 1098fc56f6fbSMike Snitzer argv += args_used; 1099fc56f6fbSMike Snitzer argc -= args_used; 1100fc56f6fbSMike Snitzer 110110b8106aSMike Snitzer r = dm_get_device(ti, origin_path, 0, ti->len, origin_mode, &s->origin); 11021da177e4SLinus Torvalds if (r) { 11031da177e4SLinus Torvalds ti->error = "Cannot get origin device"; 1104fee1998eSJonathan Brassow goto bad_origin; 11051da177e4SLinus Torvalds } 11061da177e4SLinus Torvalds 1107fc56f6fbSMike Snitzer s->ti = ti; 11081da177e4SLinus Torvalds s->valid = 1; 1109aa14edebSAlasdair G Kergon s->active = 0; 1110c26655caSMike Snitzer s->suspended = 0; 1111879129d2SMikulas Patocka atomic_set(&s->pending_exceptions_count, 0); 11121da177e4SLinus Torvalds init_rwsem(&s->lock); 1113c1f0c183SMike Snitzer INIT_LIST_HEAD(&s->list); 1114ca3a931fSAlasdair G Kergon spin_lock_init(&s->pe_lock); 11151e03f97eSMikulas Patocka s->state_bits = 0; 1116d8ddb1cfSMike Snitzer s->merge_failed = 0; 11179fe86254SMikulas Patocka s->first_merging_chunk = 0; 11189fe86254SMikulas Patocka s->num_merging_chunks = 0; 11199fe86254SMikulas Patocka bio_list_init(&s->bios_queued_during_merge); 11201da177e4SLinus Torvalds 11211da177e4SLinus Torvalds /* Allocate hash table for COW data */ 1122fee1998eSJonathan Brassow if (init_hash_tables(s)) { 11231da177e4SLinus Torvalds ti->error = "Unable to allocate hash table space"; 11241da177e4SLinus Torvalds r = -ENOMEM; 1125fee1998eSJonathan Brassow goto bad_hash_tables; 11261da177e4SLinus Torvalds } 11271da177e4SLinus Torvalds 1128eb69aca5SHeinz Mauelshagen r = dm_kcopyd_client_create(SNAPSHOT_PAGES, &s->kcopyd_client); 11291da177e4SLinus Torvalds if (r) { 11301da177e4SLinus Torvalds ti->error = "Could not create kcopyd client"; 1131fee1998eSJonathan Brassow goto bad_kcopyd; 11321da177e4SLinus Torvalds } 11331da177e4SLinus Torvalds 113492e86812SMikulas Patocka s->pending_pool = mempool_create_slab_pool(MIN_IOS, pending_cache); 113592e86812SMikulas Patocka if (!s->pending_pool) { 113692e86812SMikulas Patocka ti->error = "Could not allocate mempool for pending exceptions"; 1137fee1998eSJonathan Brassow goto bad_pending_pool; 113892e86812SMikulas Patocka } 113992e86812SMikulas Patocka 1140cd45daffSMikulas Patocka s->tracked_chunk_pool = mempool_create_slab_pool(MIN_IOS, 1141cd45daffSMikulas Patocka tracked_chunk_cache); 1142cd45daffSMikulas Patocka if (!s->tracked_chunk_pool) { 1143cd45daffSMikulas Patocka ti->error = "Could not allocate tracked_chunk mempool for " 1144cd45daffSMikulas Patocka "tracking reads"; 114592e86812SMikulas Patocka goto bad_tracked_chunk_pool; 1146cd45daffSMikulas Patocka } 1147cd45daffSMikulas Patocka 1148cd45daffSMikulas Patocka for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) 1149cd45daffSMikulas Patocka INIT_HLIST_HEAD(&s->tracked_chunk_hash[i]); 1150cd45daffSMikulas Patocka 1151cd45daffSMikulas Patocka spin_lock_init(&s->tracked_chunk_lock); 1152cd45daffSMikulas Patocka 1153c1f0c183SMike Snitzer bio_list_init(&s->queued_bios); 1154c1f0c183SMike Snitzer INIT_WORK(&s->queued_bios_work, flush_queued_bios); 1155c1f0c183SMike Snitzer 1156c1f0c183SMike Snitzer ti->private = s; 115710b8106aSMike Snitzer ti->num_flush_requests = num_flush_requests; 1158c1f0c183SMike Snitzer 1159c1f0c183SMike Snitzer /* Add snapshot to the list of snapshots for this origin */ 1160c1f0c183SMike Snitzer /* Exceptions aren't triggered till snapshot_resume() is called */ 1161c1f0c183SMike Snitzer r = register_snapshot(s); 1162c1f0c183SMike Snitzer if (r == -ENOMEM) { 1163c1f0c183SMike Snitzer ti->error = "Snapshot origin struct allocation failed"; 1164c1f0c183SMike Snitzer goto bad_load_and_register; 1165c1f0c183SMike Snitzer } else if (r < 0) { 1166c1f0c183SMike Snitzer /* invalid handover, register_snapshot has set ti->error */ 1167c1f0c183SMike Snitzer goto bad_load_and_register; 1168c1f0c183SMike Snitzer } 1169c1f0c183SMike Snitzer 1170c1f0c183SMike Snitzer /* 1171c1f0c183SMike Snitzer * Metadata must only be loaded into one table at once, so skip this 1172c1f0c183SMike Snitzer * if metadata will be handed over during resume. 1173c1f0c183SMike Snitzer * Chunk size will be set during the handover - set it to zero to 1174c1f0c183SMike Snitzer * ensure it's ignored. 1175c1f0c183SMike Snitzer */ 1176c1f0c183SMike Snitzer if (r > 0) { 1177c1f0c183SMike Snitzer s->store->chunk_size = 0; 1178c1f0c183SMike Snitzer return 0; 1179c1f0c183SMike Snitzer } 1180c1f0c183SMike Snitzer 1181493df71cSJonathan Brassow r = s->store->type->read_metadata(s->store, dm_add_exception, 1182493df71cSJonathan Brassow (void *)s); 11830764147bSMilan Broz if (r < 0) { 1184f9cea4f7SMark McLoughlin ti->error = "Failed to read snapshot metadata"; 1185c1f0c183SMike Snitzer goto bad_read_metadata; 11860764147bSMilan Broz } else if (r > 0) { 11870764147bSMilan Broz s->valid = 0; 11880764147bSMilan Broz DMWARN("Snapshot is marked invalid."); 1189f9cea4f7SMark McLoughlin } 1190aa14edebSAlasdair G Kergon 11913f2412dcSMikulas Patocka if (!s->store->chunk_size) { 11923f2412dcSMikulas Patocka ti->error = "Chunk size not set"; 1193c1f0c183SMike Snitzer goto bad_read_metadata; 11943f2412dcSMikulas Patocka } 1195d0216849SJonathan Brassow ti->split_io = s->store->chunk_size; 11961da177e4SLinus Torvalds 11971da177e4SLinus Torvalds return 0; 11981da177e4SLinus Torvalds 1199c1f0c183SMike Snitzer bad_read_metadata: 1200c1f0c183SMike Snitzer unregister_snapshot(s); 1201c1f0c183SMike Snitzer 1202cd45daffSMikulas Patocka bad_load_and_register: 1203cd45daffSMikulas Patocka mempool_destroy(s->tracked_chunk_pool); 1204cd45daffSMikulas Patocka 120592e86812SMikulas Patocka bad_tracked_chunk_pool: 120692e86812SMikulas Patocka mempool_destroy(s->pending_pool); 120792e86812SMikulas Patocka 1208fee1998eSJonathan Brassow bad_pending_pool: 1209eb69aca5SHeinz Mauelshagen dm_kcopyd_client_destroy(s->kcopyd_client); 12101da177e4SLinus Torvalds 1211fee1998eSJonathan Brassow bad_kcopyd: 12123510cb94SJon Brassow dm_exception_table_exit(&s->pending, pending_cache); 12133510cb94SJon Brassow dm_exception_table_exit(&s->complete, exception_cache); 12141da177e4SLinus Torvalds 1215fee1998eSJonathan Brassow bad_hash_tables: 12161da177e4SLinus Torvalds dm_put_device(ti, s->origin); 12171da177e4SLinus Torvalds 1218fee1998eSJonathan Brassow bad_origin: 1219fc56f6fbSMike Snitzer dm_exception_store_destroy(s->store); 1220fc56f6fbSMike Snitzer 1221fc56f6fbSMike Snitzer bad_store: 1222fc56f6fbSMike Snitzer dm_put_device(ti, s->cow); 1223fc56f6fbSMike Snitzer 1224fc56f6fbSMike Snitzer bad_cow: 12251da177e4SLinus Torvalds kfree(s); 12261da177e4SLinus Torvalds 1227fc56f6fbSMike Snitzer bad: 12281da177e4SLinus Torvalds return r; 12291da177e4SLinus Torvalds } 12301da177e4SLinus Torvalds 123131c93a0cSMilan Broz static void __free_exceptions(struct dm_snapshot *s) 123231c93a0cSMilan Broz { 1233eb69aca5SHeinz Mauelshagen dm_kcopyd_client_destroy(s->kcopyd_client); 123431c93a0cSMilan Broz s->kcopyd_client = NULL; 123531c93a0cSMilan Broz 12363510cb94SJon Brassow dm_exception_table_exit(&s->pending, pending_cache); 12373510cb94SJon Brassow dm_exception_table_exit(&s->complete, exception_cache); 123831c93a0cSMilan Broz } 123931c93a0cSMilan Broz 1240c1f0c183SMike Snitzer static void __handover_exceptions(struct dm_snapshot *snap_src, 1241c1f0c183SMike Snitzer struct dm_snapshot *snap_dest) 1242c1f0c183SMike Snitzer { 1243c1f0c183SMike Snitzer union { 1244c1f0c183SMike Snitzer struct dm_exception_table table_swap; 1245c1f0c183SMike Snitzer struct dm_exception_store *store_swap; 1246c1f0c183SMike Snitzer } u; 1247c1f0c183SMike Snitzer 1248c1f0c183SMike Snitzer /* 1249c1f0c183SMike Snitzer * Swap all snapshot context information between the two instances. 1250c1f0c183SMike Snitzer */ 1251c1f0c183SMike Snitzer u.table_swap = snap_dest->complete; 1252c1f0c183SMike Snitzer snap_dest->complete = snap_src->complete; 1253c1f0c183SMike Snitzer snap_src->complete = u.table_swap; 1254c1f0c183SMike Snitzer 1255c1f0c183SMike Snitzer u.store_swap = snap_dest->store; 1256c1f0c183SMike Snitzer snap_dest->store = snap_src->store; 1257c1f0c183SMike Snitzer snap_src->store = u.store_swap; 1258c1f0c183SMike Snitzer 1259c1f0c183SMike Snitzer snap_dest->store->snap = snap_dest; 1260c1f0c183SMike Snitzer snap_src->store->snap = snap_src; 1261c1f0c183SMike Snitzer 1262c1f0c183SMike Snitzer snap_dest->ti->split_io = snap_dest->store->chunk_size; 1263c1f0c183SMike Snitzer snap_dest->valid = snap_src->valid; 1264c1f0c183SMike Snitzer 1265c1f0c183SMike Snitzer /* 1266c1f0c183SMike Snitzer * Set source invalid to ensure it receives no further I/O. 1267c1f0c183SMike Snitzer */ 1268c1f0c183SMike Snitzer snap_src->valid = 0; 1269c1f0c183SMike Snitzer } 1270c1f0c183SMike Snitzer 12711da177e4SLinus Torvalds static void snapshot_dtr(struct dm_target *ti) 12721da177e4SLinus Torvalds { 1273cd45daffSMikulas Patocka #ifdef CONFIG_DM_DEBUG 1274cd45daffSMikulas Patocka int i; 1275cd45daffSMikulas Patocka #endif 1276028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 1277c1f0c183SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 12781da177e4SLinus Torvalds 1279ca3a931fSAlasdair G Kergon flush_workqueue(ksnapd); 1280ca3a931fSAlasdair G Kergon 1281c1f0c183SMike Snitzer down_read(&_origins_lock); 1282c1f0c183SMike Snitzer /* Check whether exception handover must be cancelled */ 12839d3b15c4SMikulas Patocka (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); 1284c1f0c183SMike Snitzer if (snap_src && snap_dest && (s == snap_src)) { 1285c1f0c183SMike Snitzer down_write(&snap_dest->lock); 1286c1f0c183SMike Snitzer snap_dest->valid = 0; 1287c1f0c183SMike Snitzer up_write(&snap_dest->lock); 1288c1f0c183SMike Snitzer DMERR("Cancelling snapshot handover."); 1289c1f0c183SMike Snitzer } 1290c1f0c183SMike Snitzer up_read(&_origins_lock); 1291c1f0c183SMike Snitzer 12921e03f97eSMikulas Patocka if (dm_target_is_snapshot_merge(ti)) 12931e03f97eSMikulas Patocka stop_merge(s); 12941e03f97eSMikulas Patocka 1295138728dcSAlasdair G Kergon /* Prevent further origin writes from using this snapshot. */ 1296138728dcSAlasdair G Kergon /* After this returns there can be no new kcopyd jobs. */ 12971da177e4SLinus Torvalds unregister_snapshot(s); 12981da177e4SLinus Torvalds 1299879129d2SMikulas Patocka while (atomic_read(&s->pending_exceptions_count)) 130090fa1527SMikulas Patocka msleep(1); 1301879129d2SMikulas Patocka /* 1302879129d2SMikulas Patocka * Ensure instructions in mempool_destroy aren't reordered 1303879129d2SMikulas Patocka * before atomic_read. 1304879129d2SMikulas Patocka */ 1305879129d2SMikulas Patocka smp_mb(); 1306879129d2SMikulas Patocka 1307cd45daffSMikulas Patocka #ifdef CONFIG_DM_DEBUG 1308cd45daffSMikulas Patocka for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) 1309cd45daffSMikulas Patocka BUG_ON(!hlist_empty(&s->tracked_chunk_hash[i])); 1310cd45daffSMikulas Patocka #endif 1311cd45daffSMikulas Patocka 1312cd45daffSMikulas Patocka mempool_destroy(s->tracked_chunk_pool); 1313cd45daffSMikulas Patocka 131431c93a0cSMilan Broz __free_exceptions(s); 13151da177e4SLinus Torvalds 131692e86812SMikulas Patocka mempool_destroy(s->pending_pool); 131792e86812SMikulas Patocka 13181da177e4SLinus Torvalds dm_put_device(ti, s->origin); 1319fee1998eSJonathan Brassow 1320fee1998eSJonathan Brassow dm_exception_store_destroy(s->store); 1321138728dcSAlasdair G Kergon 1322fc56f6fbSMike Snitzer dm_put_device(ti, s->cow); 1323fc56f6fbSMike Snitzer 13241da177e4SLinus Torvalds kfree(s); 13251da177e4SLinus Torvalds } 13261da177e4SLinus Torvalds 13271da177e4SLinus Torvalds /* 13281da177e4SLinus Torvalds * Flush a list of buffers. 13291da177e4SLinus Torvalds */ 13301da177e4SLinus Torvalds static void flush_bios(struct bio *bio) 13311da177e4SLinus Torvalds { 13321da177e4SLinus Torvalds struct bio *n; 13331da177e4SLinus Torvalds 13341da177e4SLinus Torvalds while (bio) { 13351da177e4SLinus Torvalds n = bio->bi_next; 13361da177e4SLinus Torvalds bio->bi_next = NULL; 13371da177e4SLinus Torvalds generic_make_request(bio); 13381da177e4SLinus Torvalds bio = n; 13391da177e4SLinus Torvalds } 13401da177e4SLinus Torvalds } 13411da177e4SLinus Torvalds 1342c4028958SDavid Howells static void flush_queued_bios(struct work_struct *work) 1343ca3a931fSAlasdair G Kergon { 1344c4028958SDavid Howells struct dm_snapshot *s = 1345c4028958SDavid Howells container_of(work, struct dm_snapshot, queued_bios_work); 1346ca3a931fSAlasdair G Kergon struct bio *queued_bios; 1347ca3a931fSAlasdair G Kergon unsigned long flags; 1348ca3a931fSAlasdair G Kergon 1349ca3a931fSAlasdair G Kergon spin_lock_irqsave(&s->pe_lock, flags); 1350ca3a931fSAlasdair G Kergon queued_bios = bio_list_get(&s->queued_bios); 1351ca3a931fSAlasdair G Kergon spin_unlock_irqrestore(&s->pe_lock, flags); 1352ca3a931fSAlasdair G Kergon 1353ca3a931fSAlasdair G Kergon flush_bios(queued_bios); 1354ca3a931fSAlasdair G Kergon } 1355ca3a931fSAlasdair G Kergon 1356515ad66cSMikulas Patocka static int do_origin(struct dm_dev *origin, struct bio *bio); 1357515ad66cSMikulas Patocka 1358515ad66cSMikulas Patocka /* 1359515ad66cSMikulas Patocka * Flush a list of buffers. 1360515ad66cSMikulas Patocka */ 1361515ad66cSMikulas Patocka static void retry_origin_bios(struct dm_snapshot *s, struct bio *bio) 1362515ad66cSMikulas Patocka { 1363515ad66cSMikulas Patocka struct bio *n; 1364515ad66cSMikulas Patocka int r; 1365515ad66cSMikulas Patocka 1366515ad66cSMikulas Patocka while (bio) { 1367515ad66cSMikulas Patocka n = bio->bi_next; 1368515ad66cSMikulas Patocka bio->bi_next = NULL; 1369515ad66cSMikulas Patocka r = do_origin(s->origin, bio); 1370515ad66cSMikulas Patocka if (r == DM_MAPIO_REMAPPED) 1371515ad66cSMikulas Patocka generic_make_request(bio); 1372515ad66cSMikulas Patocka bio = n; 1373515ad66cSMikulas Patocka } 1374515ad66cSMikulas Patocka } 1375515ad66cSMikulas Patocka 13761da177e4SLinus Torvalds /* 13771da177e4SLinus Torvalds * Error a list of buffers. 13781da177e4SLinus Torvalds */ 13791da177e4SLinus Torvalds static void error_bios(struct bio *bio) 13801da177e4SLinus Torvalds { 13811da177e4SLinus Torvalds struct bio *n; 13821da177e4SLinus Torvalds 13831da177e4SLinus Torvalds while (bio) { 13841da177e4SLinus Torvalds n = bio->bi_next; 13851da177e4SLinus Torvalds bio->bi_next = NULL; 13866712ecf8SNeilBrown bio_io_error(bio); 13871da177e4SLinus Torvalds bio = n; 13881da177e4SLinus Torvalds } 13891da177e4SLinus Torvalds } 13901da177e4SLinus Torvalds 1391695368acSAlasdair G Kergon static void __invalidate_snapshot(struct dm_snapshot *s, int err) 139276df1c65SAlasdair G Kergon { 139376df1c65SAlasdair G Kergon if (!s->valid) 139476df1c65SAlasdair G Kergon return; 139576df1c65SAlasdair G Kergon 139676df1c65SAlasdair G Kergon if (err == -EIO) 139776df1c65SAlasdair G Kergon DMERR("Invalidating snapshot: Error reading/writing."); 139876df1c65SAlasdair G Kergon else if (err == -ENOMEM) 139976df1c65SAlasdair G Kergon DMERR("Invalidating snapshot: Unable to allocate exception."); 140076df1c65SAlasdair G Kergon 1401493df71cSJonathan Brassow if (s->store->type->drop_snapshot) 1402493df71cSJonathan Brassow s->store->type->drop_snapshot(s->store); 140376df1c65SAlasdair G Kergon 140476df1c65SAlasdair G Kergon s->valid = 0; 140576df1c65SAlasdair G Kergon 1406fc56f6fbSMike Snitzer dm_table_event(s->ti->table); 140776df1c65SAlasdair G Kergon } 140876df1c65SAlasdair G Kergon 1409028867acSAlasdair G Kergon static void pending_complete(struct dm_snap_pending_exception *pe, int success) 14101da177e4SLinus Torvalds { 14111d4989c8SJon Brassow struct dm_exception *e; 14121da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 14139d493fa8SAlasdair G Kergon struct bio *origin_bios = NULL; 14149d493fa8SAlasdair G Kergon struct bio *snapshot_bios = NULL; 14159d493fa8SAlasdair G Kergon int error = 0; 14161da177e4SLinus Torvalds 141776df1c65SAlasdair G Kergon if (!success) { 141876df1c65SAlasdair G Kergon /* Read/write error - snapshot is unusable */ 14191da177e4SLinus Torvalds down_write(&s->lock); 1420695368acSAlasdair G Kergon __invalidate_snapshot(s, -EIO); 14219d493fa8SAlasdair G Kergon error = 1; 142276df1c65SAlasdair G Kergon goto out; 142376df1c65SAlasdair G Kergon } 142476df1c65SAlasdair G Kergon 14253510cb94SJon Brassow e = alloc_completed_exception(); 142676df1c65SAlasdair G Kergon if (!e) { 142776df1c65SAlasdair G Kergon down_write(&s->lock); 1428695368acSAlasdair G Kergon __invalidate_snapshot(s, -ENOMEM); 14299d493fa8SAlasdair G Kergon error = 1; 14301da177e4SLinus Torvalds goto out; 14311da177e4SLinus Torvalds } 14321da177e4SLinus Torvalds *e = pe->e; 14331da177e4SLinus Torvalds 14349d493fa8SAlasdair G Kergon down_write(&s->lock); 14359d493fa8SAlasdair G Kergon if (!s->valid) { 14363510cb94SJon Brassow free_completed_exception(e); 14379d493fa8SAlasdair G Kergon error = 1; 14389d493fa8SAlasdair G Kergon goto out; 14399d493fa8SAlasdair G Kergon } 14409d493fa8SAlasdair G Kergon 1441615d1eb9SMike Snitzer /* Check for conflicting reads */ 1442615d1eb9SMike Snitzer __check_for_conflicting_io(s, pe->e.old_chunk); 1443a8d41b59SMikulas Patocka 1444a8d41b59SMikulas Patocka /* 14451da177e4SLinus Torvalds * Add a proper exception, and remove the 14461da177e4SLinus Torvalds * in-flight exception from the list. 14471da177e4SLinus Torvalds */ 14483510cb94SJon Brassow dm_insert_exception(&s->complete, e); 14491da177e4SLinus Torvalds 14501da177e4SLinus Torvalds out: 14513510cb94SJon Brassow dm_remove_exception(&pe->e); 14529d493fa8SAlasdair G Kergon snapshot_bios = bio_list_get(&pe->snapshot_bios); 1453515ad66cSMikulas Patocka origin_bios = bio_list_get(&pe->origin_bios); 1454515ad66cSMikulas Patocka free_pending_exception(pe); 1455b4b610f6SAlasdair G Kergon 145673dfd078SMikulas Patocka increment_pending_exceptions_done_count(); 145773dfd078SMikulas Patocka 14589d493fa8SAlasdair G Kergon up_write(&s->lock); 14599d493fa8SAlasdair G Kergon 14609d493fa8SAlasdair G Kergon /* Submit any pending write bios */ 14619d493fa8SAlasdair G Kergon if (error) 14629d493fa8SAlasdair G Kergon error_bios(snapshot_bios); 14639d493fa8SAlasdair G Kergon else 14649d493fa8SAlasdair G Kergon flush_bios(snapshot_bios); 14659d493fa8SAlasdair G Kergon 1466515ad66cSMikulas Patocka retry_origin_bios(s, origin_bios); 14671da177e4SLinus Torvalds } 14681da177e4SLinus Torvalds 14691da177e4SLinus Torvalds static void commit_callback(void *context, int success) 14701da177e4SLinus Torvalds { 1471028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = context; 1472028867acSAlasdair G Kergon 14731da177e4SLinus Torvalds pending_complete(pe, success); 14741da177e4SLinus Torvalds } 14751da177e4SLinus Torvalds 14761da177e4SLinus Torvalds /* 14771da177e4SLinus Torvalds * Called when the copy I/O has finished. kcopyd actually runs 14781da177e4SLinus Torvalds * this code so don't block. 14791da177e4SLinus Torvalds */ 14804cdc1d1fSAlasdair G Kergon static void copy_callback(int read_err, unsigned long write_err, void *context) 14811da177e4SLinus Torvalds { 1482028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = context; 14831da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 14841da177e4SLinus Torvalds 14851da177e4SLinus Torvalds if (read_err || write_err) 14861da177e4SLinus Torvalds pending_complete(pe, 0); 14871da177e4SLinus Torvalds 14881da177e4SLinus Torvalds else 14891da177e4SLinus Torvalds /* Update the metadata if we are persistent */ 1490493df71cSJonathan Brassow s->store->type->commit_exception(s->store, &pe->e, 1491b2a11465SJonathan Brassow commit_callback, pe); 14921da177e4SLinus Torvalds } 14931da177e4SLinus Torvalds 14941da177e4SLinus Torvalds /* 14951da177e4SLinus Torvalds * Dispatches the copy operation to kcopyd. 14961da177e4SLinus Torvalds */ 1497028867acSAlasdair G Kergon static void start_copy(struct dm_snap_pending_exception *pe) 14981da177e4SLinus Torvalds { 14991da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 150022a1ceb1SHeinz Mauelshagen struct dm_io_region src, dest; 15011da177e4SLinus Torvalds struct block_device *bdev = s->origin->bdev; 15021da177e4SLinus Torvalds sector_t dev_size; 15031da177e4SLinus Torvalds 15041da177e4SLinus Torvalds dev_size = get_dev_size(bdev); 15051da177e4SLinus Torvalds 15061da177e4SLinus Torvalds src.bdev = bdev; 150771fab00aSJonathan Brassow src.sector = chunk_to_sector(s->store, pe->e.old_chunk); 1508df96eee6SMikulas Patocka src.count = min((sector_t)s->store->chunk_size, dev_size - src.sector); 15091da177e4SLinus Torvalds 1510fc56f6fbSMike Snitzer dest.bdev = s->cow->bdev; 151171fab00aSJonathan Brassow dest.sector = chunk_to_sector(s->store, pe->e.new_chunk); 15121da177e4SLinus Torvalds dest.count = src.count; 15131da177e4SLinus Torvalds 15141da177e4SLinus Torvalds /* Hand over to kcopyd */ 1515eb69aca5SHeinz Mauelshagen dm_kcopyd_copy(s->kcopyd_client, 15161da177e4SLinus Torvalds &src, 1, &dest, 0, copy_callback, pe); 15171da177e4SLinus Torvalds } 15181da177e4SLinus Torvalds 15192913808eSMikulas Patocka static struct dm_snap_pending_exception * 15202913808eSMikulas Patocka __lookup_pending_exception(struct dm_snapshot *s, chunk_t chunk) 15212913808eSMikulas Patocka { 15223510cb94SJon Brassow struct dm_exception *e = dm_lookup_exception(&s->pending, chunk); 15232913808eSMikulas Patocka 15242913808eSMikulas Patocka if (!e) 15252913808eSMikulas Patocka return NULL; 15262913808eSMikulas Patocka 15272913808eSMikulas Patocka return container_of(e, struct dm_snap_pending_exception, e); 15282913808eSMikulas Patocka } 15292913808eSMikulas Patocka 15301da177e4SLinus Torvalds /* 15311da177e4SLinus Torvalds * Looks to see if this snapshot already has a pending exception 15321da177e4SLinus Torvalds * for this chunk, otherwise it allocates a new one and inserts 15331da177e4SLinus Torvalds * it into the pending table. 15341da177e4SLinus Torvalds * 15351da177e4SLinus Torvalds * NOTE: a write lock must be held on snap->lock before calling 15361da177e4SLinus Torvalds * this. 15371da177e4SLinus Torvalds */ 1538028867acSAlasdair G Kergon static struct dm_snap_pending_exception * 1539c6621392SMikulas Patocka __find_pending_exception(struct dm_snapshot *s, 1540c6621392SMikulas Patocka struct dm_snap_pending_exception *pe, chunk_t chunk) 15411da177e4SLinus Torvalds { 1542c6621392SMikulas Patocka struct dm_snap_pending_exception *pe2; 154376df1c65SAlasdair G Kergon 15442913808eSMikulas Patocka pe2 = __lookup_pending_exception(s, chunk); 15452913808eSMikulas Patocka if (pe2) { 15461da177e4SLinus Torvalds free_pending_exception(pe); 15472913808eSMikulas Patocka return pe2; 154876df1c65SAlasdair G Kergon } 154976df1c65SAlasdair G Kergon 15501da177e4SLinus Torvalds pe->e.old_chunk = chunk; 15511da177e4SLinus Torvalds bio_list_init(&pe->origin_bios); 15521da177e4SLinus Torvalds bio_list_init(&pe->snapshot_bios); 15531da177e4SLinus Torvalds pe->started = 0; 15541da177e4SLinus Torvalds 1555493df71cSJonathan Brassow if (s->store->type->prepare_exception(s->store, &pe->e)) { 15561da177e4SLinus Torvalds free_pending_exception(pe); 15571da177e4SLinus Torvalds return NULL; 15581da177e4SLinus Torvalds } 15591da177e4SLinus Torvalds 15603510cb94SJon Brassow dm_insert_exception(&s->pending, &pe->e); 15611da177e4SLinus Torvalds 15621da177e4SLinus Torvalds return pe; 15631da177e4SLinus Torvalds } 15641da177e4SLinus Torvalds 15651d4989c8SJon Brassow static void remap_exception(struct dm_snapshot *s, struct dm_exception *e, 1566d74f81f8SMilan Broz struct bio *bio, chunk_t chunk) 15671da177e4SLinus Torvalds { 1568fc56f6fbSMike Snitzer bio->bi_bdev = s->cow->bdev; 156971fab00aSJonathan Brassow bio->bi_sector = chunk_to_sector(s->store, 157071fab00aSJonathan Brassow dm_chunk_number(e->new_chunk) + 1571d74f81f8SMilan Broz (chunk - e->old_chunk)) + 157271fab00aSJonathan Brassow (bio->bi_sector & 157371fab00aSJonathan Brassow s->store->chunk_mask); 15741da177e4SLinus Torvalds } 15751da177e4SLinus Torvalds 15761da177e4SLinus Torvalds static int snapshot_map(struct dm_target *ti, struct bio *bio, 15771da177e4SLinus Torvalds union map_info *map_context) 15781da177e4SLinus Torvalds { 15791d4989c8SJon Brassow struct dm_exception *e; 1580028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 1581d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED; 15821da177e4SLinus Torvalds chunk_t chunk; 1583028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = NULL; 15841da177e4SLinus Torvalds 1585494b3ee7SMikulas Patocka if (unlikely(bio_empty_barrier(bio))) { 1586fc56f6fbSMike Snitzer bio->bi_bdev = s->cow->bdev; 1587494b3ee7SMikulas Patocka return DM_MAPIO_REMAPPED; 1588494b3ee7SMikulas Patocka } 1589494b3ee7SMikulas Patocka 159071fab00aSJonathan Brassow chunk = sector_to_chunk(s->store, bio->bi_sector); 15911da177e4SLinus Torvalds 15921da177e4SLinus Torvalds /* Full snapshots are not usable */ 159376df1c65SAlasdair G Kergon /* To get here the table must be live so s->active is always set. */ 15941da177e4SLinus Torvalds if (!s->valid) 1595f6a80ea8SAlasdair G Kergon return -EIO; 15961da177e4SLinus Torvalds 15971da177e4SLinus Torvalds /* FIXME: should only take write lock if we need 15981da177e4SLinus Torvalds * to copy an exception */ 15991da177e4SLinus Torvalds down_write(&s->lock); 16001da177e4SLinus Torvalds 160176df1c65SAlasdair G Kergon if (!s->valid) { 160276df1c65SAlasdair G Kergon r = -EIO; 160376df1c65SAlasdair G Kergon goto out_unlock; 160476df1c65SAlasdair G Kergon } 160576df1c65SAlasdair G Kergon 16061da177e4SLinus Torvalds /* If the block is already remapped - use that, else remap it */ 16073510cb94SJon Brassow e = dm_lookup_exception(&s->complete, chunk); 16081da177e4SLinus Torvalds if (e) { 1609d74f81f8SMilan Broz remap_exception(s, e, bio, chunk); 161076df1c65SAlasdair G Kergon goto out_unlock; 161176df1c65SAlasdair G Kergon } 16121da177e4SLinus Torvalds 1613ba40a2aaSAlasdair G Kergon /* 1614ba40a2aaSAlasdair G Kergon * Write to snapshot - higher level takes care of RW/RO 1615ba40a2aaSAlasdair G Kergon * flags so we should only get this if we are 1616ba40a2aaSAlasdair G Kergon * writeable. 1617ba40a2aaSAlasdair G Kergon */ 1618ba40a2aaSAlasdair G Kergon if (bio_rw(bio) == WRITE) { 16192913808eSMikulas Patocka pe = __lookup_pending_exception(s, chunk); 16202913808eSMikulas Patocka if (!pe) { 1621c6621392SMikulas Patocka up_write(&s->lock); 1622c6621392SMikulas Patocka pe = alloc_pending_exception(s); 1623c6621392SMikulas Patocka down_write(&s->lock); 1624c6621392SMikulas Patocka 1625c6621392SMikulas Patocka if (!s->valid) { 1626c6621392SMikulas Patocka free_pending_exception(pe); 1627c6621392SMikulas Patocka r = -EIO; 1628c6621392SMikulas Patocka goto out_unlock; 1629c6621392SMikulas Patocka } 1630c6621392SMikulas Patocka 16313510cb94SJon Brassow e = dm_lookup_exception(&s->complete, chunk); 163235bf659bSMikulas Patocka if (e) { 163335bf659bSMikulas Patocka free_pending_exception(pe); 163435bf659bSMikulas Patocka remap_exception(s, e, bio, chunk); 163535bf659bSMikulas Patocka goto out_unlock; 163635bf659bSMikulas Patocka } 163735bf659bSMikulas Patocka 1638c6621392SMikulas Patocka pe = __find_pending_exception(s, pe, chunk); 16391da177e4SLinus Torvalds if (!pe) { 1640695368acSAlasdair G Kergon __invalidate_snapshot(s, -ENOMEM); 16411da177e4SLinus Torvalds r = -EIO; 164276df1c65SAlasdair G Kergon goto out_unlock; 164376df1c65SAlasdair G Kergon } 16442913808eSMikulas Patocka } 164576df1c65SAlasdair G Kergon 1646d74f81f8SMilan Broz remap_exception(s, &pe->e, bio, chunk); 16471da177e4SLinus Torvalds bio_list_add(&pe->snapshot_bios, bio); 16481da177e4SLinus Torvalds 1649d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 1650ba40a2aaSAlasdair G Kergon 16511da177e4SLinus Torvalds if (!pe->started) { 16521da177e4SLinus Torvalds /* this is protected by snap->lock */ 16531da177e4SLinus Torvalds pe->started = 1; 165476df1c65SAlasdair G Kergon up_write(&s->lock); 165576df1c65SAlasdair G Kergon start_copy(pe); 1656ba40a2aaSAlasdair G Kergon goto out; 1657ba40a2aaSAlasdair G Kergon } 1658cd45daffSMikulas Patocka } else { 16591da177e4SLinus Torvalds bio->bi_bdev = s->origin->bdev; 1660cd45daffSMikulas Patocka map_context->ptr = track_chunk(s, chunk); 1661cd45daffSMikulas Patocka } 16621da177e4SLinus Torvalds 1663ba40a2aaSAlasdair G Kergon out_unlock: 1664ba40a2aaSAlasdair G Kergon up_write(&s->lock); 1665ba40a2aaSAlasdair G Kergon out: 16661da177e4SLinus Torvalds return r; 16671da177e4SLinus Torvalds } 16681da177e4SLinus Torvalds 16693452c2a1SMikulas Patocka /* 16703452c2a1SMikulas Patocka * A snapshot-merge target behaves like a combination of a snapshot 16713452c2a1SMikulas Patocka * target and a snapshot-origin target. It only generates new 16723452c2a1SMikulas Patocka * exceptions in other snapshots and not in the one that is being 16733452c2a1SMikulas Patocka * merged. 16743452c2a1SMikulas Patocka * 16753452c2a1SMikulas Patocka * For each chunk, if there is an existing exception, it is used to 16763452c2a1SMikulas Patocka * redirect I/O to the cow device. Otherwise I/O is sent to the origin, 16773452c2a1SMikulas Patocka * which in turn might generate exceptions in other snapshots. 16789fe86254SMikulas Patocka * If merging is currently taking place on the chunk in question, the 16799fe86254SMikulas Patocka * I/O is deferred by adding it to s->bios_queued_during_merge. 16803452c2a1SMikulas Patocka */ 16813452c2a1SMikulas Patocka static int snapshot_merge_map(struct dm_target *ti, struct bio *bio, 16823452c2a1SMikulas Patocka union map_info *map_context) 16833452c2a1SMikulas Patocka { 16843452c2a1SMikulas Patocka struct dm_exception *e; 16853452c2a1SMikulas Patocka struct dm_snapshot *s = ti->private; 16863452c2a1SMikulas Patocka int r = DM_MAPIO_REMAPPED; 16873452c2a1SMikulas Patocka chunk_t chunk; 16883452c2a1SMikulas Patocka 168910b8106aSMike Snitzer if (unlikely(bio_empty_barrier(bio))) { 169010b8106aSMike Snitzer if (!map_context->flush_request) 169110b8106aSMike Snitzer bio->bi_bdev = s->origin->bdev; 169210b8106aSMike Snitzer else 169310b8106aSMike Snitzer bio->bi_bdev = s->cow->bdev; 169410b8106aSMike Snitzer map_context->ptr = NULL; 169510b8106aSMike Snitzer return DM_MAPIO_REMAPPED; 169610b8106aSMike Snitzer } 169710b8106aSMike Snitzer 16983452c2a1SMikulas Patocka chunk = sector_to_chunk(s->store, bio->bi_sector); 16993452c2a1SMikulas Patocka 17009fe86254SMikulas Patocka down_write(&s->lock); 17013452c2a1SMikulas Patocka 1702d2fdb776SMikulas Patocka /* Full merging snapshots are redirected to the origin */ 1703d2fdb776SMikulas Patocka if (!s->valid) 1704d2fdb776SMikulas Patocka goto redirect_to_origin; 17053452c2a1SMikulas Patocka 17063452c2a1SMikulas Patocka /* If the block is already remapped - use that */ 17073452c2a1SMikulas Patocka e = dm_lookup_exception(&s->complete, chunk); 17083452c2a1SMikulas Patocka if (e) { 17099fe86254SMikulas Patocka /* Queue writes overlapping with chunks being merged */ 17109fe86254SMikulas Patocka if (bio_rw(bio) == WRITE && 17119fe86254SMikulas Patocka chunk >= s->first_merging_chunk && 17129fe86254SMikulas Patocka chunk < (s->first_merging_chunk + 17139fe86254SMikulas Patocka s->num_merging_chunks)) { 17149fe86254SMikulas Patocka bio->bi_bdev = s->origin->bdev; 17159fe86254SMikulas Patocka bio_list_add(&s->bios_queued_during_merge, bio); 17169fe86254SMikulas Patocka r = DM_MAPIO_SUBMITTED; 17179fe86254SMikulas Patocka goto out_unlock; 17189fe86254SMikulas Patocka } 171917aa0332SMikulas Patocka 17203452c2a1SMikulas Patocka remap_exception(s, e, bio, chunk); 172117aa0332SMikulas Patocka 172217aa0332SMikulas Patocka if (bio_rw(bio) == WRITE) 172317aa0332SMikulas Patocka map_context->ptr = track_chunk(s, chunk); 17243452c2a1SMikulas Patocka goto out_unlock; 17253452c2a1SMikulas Patocka } 17263452c2a1SMikulas Patocka 1727d2fdb776SMikulas Patocka redirect_to_origin: 17283452c2a1SMikulas Patocka bio->bi_bdev = s->origin->bdev; 17293452c2a1SMikulas Patocka 17303452c2a1SMikulas Patocka if (bio_rw(bio) == WRITE) { 17319fe86254SMikulas Patocka up_write(&s->lock); 17323452c2a1SMikulas Patocka return do_origin(s->origin, bio); 17333452c2a1SMikulas Patocka } 17343452c2a1SMikulas Patocka 17353452c2a1SMikulas Patocka out_unlock: 17369fe86254SMikulas Patocka up_write(&s->lock); 17373452c2a1SMikulas Patocka 17383452c2a1SMikulas Patocka return r; 17393452c2a1SMikulas Patocka } 17403452c2a1SMikulas Patocka 1741cd45daffSMikulas Patocka static int snapshot_end_io(struct dm_target *ti, struct bio *bio, 1742cd45daffSMikulas Patocka int error, union map_info *map_context) 1743cd45daffSMikulas Patocka { 1744cd45daffSMikulas Patocka struct dm_snapshot *s = ti->private; 1745cd45daffSMikulas Patocka struct dm_snap_tracked_chunk *c = map_context->ptr; 1746cd45daffSMikulas Patocka 1747cd45daffSMikulas Patocka if (c) 1748cd45daffSMikulas Patocka stop_tracking_chunk(s, c); 1749cd45daffSMikulas Patocka 1750cd45daffSMikulas Patocka return 0; 1751cd45daffSMikulas Patocka } 1752cd45daffSMikulas Patocka 17531e03f97eSMikulas Patocka static void snapshot_merge_presuspend(struct dm_target *ti) 17541e03f97eSMikulas Patocka { 17551e03f97eSMikulas Patocka struct dm_snapshot *s = ti->private; 17561e03f97eSMikulas Patocka 17571e03f97eSMikulas Patocka stop_merge(s); 17581e03f97eSMikulas Patocka } 17591e03f97eSMikulas Patocka 1760c26655caSMike Snitzer static void snapshot_postsuspend(struct dm_target *ti) 1761c26655caSMike Snitzer { 1762c26655caSMike Snitzer struct dm_snapshot *s = ti->private; 1763c26655caSMike Snitzer 1764c26655caSMike Snitzer down_write(&s->lock); 1765c26655caSMike Snitzer s->suspended = 1; 1766c26655caSMike Snitzer up_write(&s->lock); 1767c26655caSMike Snitzer } 1768c26655caSMike Snitzer 1769c1f0c183SMike Snitzer static int snapshot_preresume(struct dm_target *ti) 1770c1f0c183SMike Snitzer { 1771c1f0c183SMike Snitzer int r = 0; 1772c1f0c183SMike Snitzer struct dm_snapshot *s = ti->private; 1773c1f0c183SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 1774c1f0c183SMike Snitzer 1775c1f0c183SMike Snitzer down_read(&_origins_lock); 17769d3b15c4SMikulas Patocka (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); 1777c1f0c183SMike Snitzer if (snap_src && snap_dest) { 1778c1f0c183SMike Snitzer down_read(&snap_src->lock); 1779c1f0c183SMike Snitzer if (s == snap_src) { 1780c1f0c183SMike Snitzer DMERR("Unable to resume snapshot source until " 1781c1f0c183SMike Snitzer "handover completes."); 1782c1f0c183SMike Snitzer r = -EINVAL; 1783c1f0c183SMike Snitzer } else if (!snap_src->suspended) { 1784c1f0c183SMike Snitzer DMERR("Unable to perform snapshot handover until " 1785c1f0c183SMike Snitzer "source is suspended."); 1786c1f0c183SMike Snitzer r = -EINVAL; 1787c1f0c183SMike Snitzer } 1788c1f0c183SMike Snitzer up_read(&snap_src->lock); 1789c1f0c183SMike Snitzer } 1790c1f0c183SMike Snitzer up_read(&_origins_lock); 1791c1f0c183SMike Snitzer 1792c1f0c183SMike Snitzer return r; 1793c1f0c183SMike Snitzer } 1794c1f0c183SMike Snitzer 17951da177e4SLinus Torvalds static void snapshot_resume(struct dm_target *ti) 17961da177e4SLinus Torvalds { 1797028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 1798c1f0c183SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 1799c1f0c183SMike Snitzer 1800c1f0c183SMike Snitzer down_read(&_origins_lock); 18019d3b15c4SMikulas Patocka (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); 1802c1f0c183SMike Snitzer if (snap_src && snap_dest) { 1803c1f0c183SMike Snitzer down_write(&snap_src->lock); 1804c1f0c183SMike Snitzer down_write_nested(&snap_dest->lock, SINGLE_DEPTH_NESTING); 1805c1f0c183SMike Snitzer __handover_exceptions(snap_src, snap_dest); 1806c1f0c183SMike Snitzer up_write(&snap_dest->lock); 1807c1f0c183SMike Snitzer up_write(&snap_src->lock); 1808c1f0c183SMike Snitzer } 1809c1f0c183SMike Snitzer up_read(&_origins_lock); 1810c1f0c183SMike Snitzer 1811c1f0c183SMike Snitzer /* Now we have correct chunk size, reregister */ 1812c1f0c183SMike Snitzer reregister_snapshot(s); 18131da177e4SLinus Torvalds 1814aa14edebSAlasdair G Kergon down_write(&s->lock); 1815aa14edebSAlasdair G Kergon s->active = 1; 1816c26655caSMike Snitzer s->suspended = 0; 1817aa14edebSAlasdair G Kergon up_write(&s->lock); 18181da177e4SLinus Torvalds } 18191da177e4SLinus Torvalds 18201e03f97eSMikulas Patocka static sector_t get_origin_minimum_chunksize(struct block_device *bdev) 18211e03f97eSMikulas Patocka { 18221e03f97eSMikulas Patocka sector_t min_chunksize; 18231e03f97eSMikulas Patocka 18241e03f97eSMikulas Patocka down_read(&_origins_lock); 18251e03f97eSMikulas Patocka min_chunksize = __minimum_chunk_size(__lookup_origin(bdev)); 18261e03f97eSMikulas Patocka up_read(&_origins_lock); 18271e03f97eSMikulas Patocka 18281e03f97eSMikulas Patocka return min_chunksize; 18291e03f97eSMikulas Patocka } 18301e03f97eSMikulas Patocka 18311e03f97eSMikulas Patocka static void snapshot_merge_resume(struct dm_target *ti) 18321e03f97eSMikulas Patocka { 18331e03f97eSMikulas Patocka struct dm_snapshot *s = ti->private; 18341e03f97eSMikulas Patocka 18351e03f97eSMikulas Patocka /* 18361e03f97eSMikulas Patocka * Handover exceptions from existing snapshot. 18371e03f97eSMikulas Patocka */ 18381e03f97eSMikulas Patocka snapshot_resume(ti); 18391e03f97eSMikulas Patocka 18401e03f97eSMikulas Patocka /* 18411e03f97eSMikulas Patocka * snapshot-merge acts as an origin, so set ti->split_io 18421e03f97eSMikulas Patocka */ 18431e03f97eSMikulas Patocka ti->split_io = get_origin_minimum_chunksize(s->origin->bdev); 18441e03f97eSMikulas Patocka 18451e03f97eSMikulas Patocka start_merge(s); 18461e03f97eSMikulas Patocka } 18471e03f97eSMikulas Patocka 18481da177e4SLinus Torvalds static int snapshot_status(struct dm_target *ti, status_type_t type, 18491da177e4SLinus Torvalds char *result, unsigned int maxlen) 18501da177e4SLinus Torvalds { 18512e4a31dfSJonathan Brassow unsigned sz = 0; 1852028867acSAlasdair G Kergon struct dm_snapshot *snap = ti->private; 18531da177e4SLinus Torvalds 18541da177e4SLinus Torvalds switch (type) { 18551da177e4SLinus Torvalds case STATUSTYPE_INFO: 185694e76572SMikulas Patocka 185794e76572SMikulas Patocka down_write(&snap->lock); 185894e76572SMikulas Patocka 18591da177e4SLinus Torvalds if (!snap->valid) 18602e4a31dfSJonathan Brassow DMEMIT("Invalid"); 1861d8ddb1cfSMike Snitzer else if (snap->merge_failed) 1862d8ddb1cfSMike Snitzer DMEMIT("Merge failed"); 18631da177e4SLinus Torvalds else { 1864985903bbSMike Snitzer if (snap->store->type->usage) { 1865985903bbSMike Snitzer sector_t total_sectors, sectors_allocated, 1866985903bbSMike Snitzer metadata_sectors; 1867985903bbSMike Snitzer snap->store->type->usage(snap->store, 1868985903bbSMike Snitzer &total_sectors, 1869985903bbSMike Snitzer §ors_allocated, 1870985903bbSMike Snitzer &metadata_sectors); 1871985903bbSMike Snitzer DMEMIT("%llu/%llu %llu", 1872985903bbSMike Snitzer (unsigned long long)sectors_allocated, 1873985903bbSMike Snitzer (unsigned long long)total_sectors, 1874985903bbSMike Snitzer (unsigned long long)metadata_sectors); 18751da177e4SLinus Torvalds } 18761da177e4SLinus Torvalds else 18772e4a31dfSJonathan Brassow DMEMIT("Unknown"); 18781da177e4SLinus Torvalds } 187994e76572SMikulas Patocka 188094e76572SMikulas Patocka up_write(&snap->lock); 188194e76572SMikulas Patocka 18821da177e4SLinus Torvalds break; 18831da177e4SLinus Torvalds 18841da177e4SLinus Torvalds case STATUSTYPE_TABLE: 18851da177e4SLinus Torvalds /* 18861da177e4SLinus Torvalds * kdevname returns a static pointer so we need 18871da177e4SLinus Torvalds * to make private copies if the output is to 18881da177e4SLinus Torvalds * make sense. 18891da177e4SLinus Torvalds */ 1890fc56f6fbSMike Snitzer DMEMIT("%s %s", snap->origin->name, snap->cow->name); 18911e302a92SJonathan Brassow snap->store->type->status(snap->store, type, result + sz, 18921e302a92SJonathan Brassow maxlen - sz); 18931da177e4SLinus Torvalds break; 18941da177e4SLinus Torvalds } 18951da177e4SLinus Torvalds 18961da177e4SLinus Torvalds return 0; 18971da177e4SLinus Torvalds } 18981da177e4SLinus Torvalds 18998811f46cSMike Snitzer static int snapshot_iterate_devices(struct dm_target *ti, 19008811f46cSMike Snitzer iterate_devices_callout_fn fn, void *data) 19018811f46cSMike Snitzer { 19028811f46cSMike Snitzer struct dm_snapshot *snap = ti->private; 19038811f46cSMike Snitzer 19048811f46cSMike Snitzer return fn(ti, snap->origin, 0, ti->len, data); 19058811f46cSMike Snitzer } 19068811f46cSMike Snitzer 19078811f46cSMike Snitzer 19081da177e4SLinus Torvalds /*----------------------------------------------------------------- 19091da177e4SLinus Torvalds * Origin methods 19101da177e4SLinus Torvalds *---------------------------------------------------------------*/ 19119eaae8ffSMikulas Patocka 19129eaae8ffSMikulas Patocka /* 19139eaae8ffSMikulas Patocka * If no exceptions need creating, DM_MAPIO_REMAPPED is returned and any 19149eaae8ffSMikulas Patocka * supplied bio was ignored. The caller may submit it immediately. 19159eaae8ffSMikulas Patocka * (No remapping actually occurs as the origin is always a direct linear 19169eaae8ffSMikulas Patocka * map.) 19179eaae8ffSMikulas Patocka * 19189eaae8ffSMikulas Patocka * If further exceptions are required, DM_MAPIO_SUBMITTED is returned 19199eaae8ffSMikulas Patocka * and any supplied bio is added to a list to be submitted once all 19209eaae8ffSMikulas Patocka * the necessary exceptions exist. 19219eaae8ffSMikulas Patocka */ 19229eaae8ffSMikulas Patocka static int __origin_write(struct list_head *snapshots, sector_t sector, 19239eaae8ffSMikulas Patocka struct bio *bio) 19241da177e4SLinus Torvalds { 1925515ad66cSMikulas Patocka int r = DM_MAPIO_REMAPPED; 19261da177e4SLinus Torvalds struct dm_snapshot *snap; 19271d4989c8SJon Brassow struct dm_exception *e; 1928515ad66cSMikulas Patocka struct dm_snap_pending_exception *pe; 1929515ad66cSMikulas Patocka struct dm_snap_pending_exception *pe_to_start_now = NULL; 1930515ad66cSMikulas Patocka struct dm_snap_pending_exception *pe_to_start_last = NULL; 19311da177e4SLinus Torvalds chunk_t chunk; 19321da177e4SLinus Torvalds 19331da177e4SLinus Torvalds /* Do all the snapshots on this origin */ 19341da177e4SLinus Torvalds list_for_each_entry (snap, snapshots, list) { 19353452c2a1SMikulas Patocka /* 19363452c2a1SMikulas Patocka * Don't make new exceptions in a merging snapshot 19373452c2a1SMikulas Patocka * because it has effectively been deleted 19383452c2a1SMikulas Patocka */ 19393452c2a1SMikulas Patocka if (dm_target_is_snapshot_merge(snap->ti)) 19403452c2a1SMikulas Patocka continue; 19413452c2a1SMikulas Patocka 194276df1c65SAlasdair G Kergon down_write(&snap->lock); 194376df1c65SAlasdair G Kergon 1944aa14edebSAlasdair G Kergon /* Only deal with valid and active snapshots */ 1945aa14edebSAlasdair G Kergon if (!snap->valid || !snap->active) 194676df1c65SAlasdair G Kergon goto next_snapshot; 19471da177e4SLinus Torvalds 1948d5e404c1SAlasdair G Kergon /* Nothing to do if writing beyond end of snapshot */ 19499eaae8ffSMikulas Patocka if (sector >= dm_table_get_size(snap->ti->table)) 195076df1c65SAlasdair G Kergon goto next_snapshot; 19511da177e4SLinus Torvalds 19521da177e4SLinus Torvalds /* 19531da177e4SLinus Torvalds * Remember, different snapshots can have 19541da177e4SLinus Torvalds * different chunk sizes. 19551da177e4SLinus Torvalds */ 19569eaae8ffSMikulas Patocka chunk = sector_to_chunk(snap->store, sector); 19571da177e4SLinus Torvalds 19581da177e4SLinus Torvalds /* 19591da177e4SLinus Torvalds * Check exception table to see if block 19601da177e4SLinus Torvalds * is already remapped in this snapshot 19611da177e4SLinus Torvalds * and trigger an exception if not. 19621da177e4SLinus Torvalds */ 19633510cb94SJon Brassow e = dm_lookup_exception(&snap->complete, chunk); 196476df1c65SAlasdair G Kergon if (e) 196576df1c65SAlasdair G Kergon goto next_snapshot; 196676df1c65SAlasdair G Kergon 19672913808eSMikulas Patocka pe = __lookup_pending_exception(snap, chunk); 19682913808eSMikulas Patocka if (!pe) { 1969c6621392SMikulas Patocka up_write(&snap->lock); 1970c6621392SMikulas Patocka pe = alloc_pending_exception(snap); 1971c6621392SMikulas Patocka down_write(&snap->lock); 1972c6621392SMikulas Patocka 1973c6621392SMikulas Patocka if (!snap->valid) { 1974c6621392SMikulas Patocka free_pending_exception(pe); 1975c6621392SMikulas Patocka goto next_snapshot; 1976c6621392SMikulas Patocka } 1977c6621392SMikulas Patocka 19783510cb94SJon Brassow e = dm_lookup_exception(&snap->complete, chunk); 197935bf659bSMikulas Patocka if (e) { 198035bf659bSMikulas Patocka free_pending_exception(pe); 198135bf659bSMikulas Patocka goto next_snapshot; 198235bf659bSMikulas Patocka } 198335bf659bSMikulas Patocka 1984c6621392SMikulas Patocka pe = __find_pending_exception(snap, pe, chunk); 19851da177e4SLinus Torvalds if (!pe) { 1986695368acSAlasdair G Kergon __invalidate_snapshot(snap, -ENOMEM); 198776df1c65SAlasdair G Kergon goto next_snapshot; 198876df1c65SAlasdair G Kergon } 19892913808eSMikulas Patocka } 19901da177e4SLinus Torvalds 1991d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 199276df1c65SAlasdair G Kergon 1993515ad66cSMikulas Patocka /* 1994515ad66cSMikulas Patocka * If an origin bio was supplied, queue it to wait for the 1995515ad66cSMikulas Patocka * completion of this exception, and start this one last, 1996515ad66cSMikulas Patocka * at the end of the function. 1997515ad66cSMikulas Patocka */ 1998515ad66cSMikulas Patocka if (bio) { 1999515ad66cSMikulas Patocka bio_list_add(&pe->origin_bios, bio); 2000515ad66cSMikulas Patocka bio = NULL; 2001515ad66cSMikulas Patocka 2002515ad66cSMikulas Patocka if (!pe->started) { 2003515ad66cSMikulas Patocka pe->started = 1; 2004515ad66cSMikulas Patocka pe_to_start_last = pe; 2005515ad66cSMikulas Patocka } 2006b4b610f6SAlasdair G Kergon } 200776df1c65SAlasdair G Kergon 2008eccf0817SAlasdair G Kergon if (!pe->started) { 2009eccf0817SAlasdair G Kergon pe->started = 1; 2010515ad66cSMikulas Patocka pe_to_start_now = pe; 2011eccf0817SAlasdair G Kergon } 20121da177e4SLinus Torvalds 201376df1c65SAlasdair G Kergon next_snapshot: 20141da177e4SLinus Torvalds up_write(&snap->lock); 2015515ad66cSMikulas Patocka 2016515ad66cSMikulas Patocka if (pe_to_start_now) { 2017515ad66cSMikulas Patocka start_copy(pe_to_start_now); 2018515ad66cSMikulas Patocka pe_to_start_now = NULL; 20191da177e4SLinus Torvalds } 2020b4b610f6SAlasdair G Kergon } 2021b4b610f6SAlasdair G Kergon 20221da177e4SLinus Torvalds /* 2023515ad66cSMikulas Patocka * Submit the exception against which the bio is queued last, 2024515ad66cSMikulas Patocka * to give the other exceptions a head start. 20251da177e4SLinus Torvalds */ 2026515ad66cSMikulas Patocka if (pe_to_start_last) 2027515ad66cSMikulas Patocka start_copy(pe_to_start_last); 20281da177e4SLinus Torvalds 20291da177e4SLinus Torvalds return r; 20301da177e4SLinus Torvalds } 20311da177e4SLinus Torvalds 20321da177e4SLinus Torvalds /* 20331da177e4SLinus Torvalds * Called on a write from the origin driver. 20341da177e4SLinus Torvalds */ 20351da177e4SLinus Torvalds static int do_origin(struct dm_dev *origin, struct bio *bio) 20361da177e4SLinus Torvalds { 20371da177e4SLinus Torvalds struct origin *o; 2038d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED; 20391da177e4SLinus Torvalds 20401da177e4SLinus Torvalds down_read(&_origins_lock); 20411da177e4SLinus Torvalds o = __lookup_origin(origin->bdev); 20421da177e4SLinus Torvalds if (o) 20439eaae8ffSMikulas Patocka r = __origin_write(&o->snapshots, bio->bi_sector, bio); 20441da177e4SLinus Torvalds up_read(&_origins_lock); 20451da177e4SLinus Torvalds 20461da177e4SLinus Torvalds return r; 20471da177e4SLinus Torvalds } 20481da177e4SLinus Torvalds 20491da177e4SLinus Torvalds /* 205073dfd078SMikulas Patocka * Trigger exceptions in all non-merging snapshots. 205173dfd078SMikulas Patocka * 205273dfd078SMikulas Patocka * The chunk size of the merging snapshot may be larger than the chunk 205373dfd078SMikulas Patocka * size of some other snapshot so we may need to reallocate multiple 205473dfd078SMikulas Patocka * chunks in other snapshots. 205573dfd078SMikulas Patocka * 205673dfd078SMikulas Patocka * We scan all the overlapping exceptions in the other snapshots. 205773dfd078SMikulas Patocka * Returns 1 if anything was reallocated and must be waited for, 205873dfd078SMikulas Patocka * otherwise returns 0. 205973dfd078SMikulas Patocka * 206073dfd078SMikulas Patocka * size must be a multiple of merging_snap's chunk_size. 206173dfd078SMikulas Patocka */ 206273dfd078SMikulas Patocka static int origin_write_extent(struct dm_snapshot *merging_snap, 206373dfd078SMikulas Patocka sector_t sector, unsigned size) 206473dfd078SMikulas Patocka { 206573dfd078SMikulas Patocka int must_wait = 0; 206673dfd078SMikulas Patocka sector_t n; 206773dfd078SMikulas Patocka struct origin *o; 206873dfd078SMikulas Patocka 206973dfd078SMikulas Patocka /* 207073dfd078SMikulas Patocka * The origin's __minimum_chunk_size() got stored in split_io 207173dfd078SMikulas Patocka * by snapshot_merge_resume(). 207273dfd078SMikulas Patocka */ 207373dfd078SMikulas Patocka down_read(&_origins_lock); 207473dfd078SMikulas Patocka o = __lookup_origin(merging_snap->origin->bdev); 207573dfd078SMikulas Patocka for (n = 0; n < size; n += merging_snap->ti->split_io) 207673dfd078SMikulas Patocka if (__origin_write(&o->snapshots, sector + n, NULL) == 207773dfd078SMikulas Patocka DM_MAPIO_SUBMITTED) 207873dfd078SMikulas Patocka must_wait = 1; 207973dfd078SMikulas Patocka up_read(&_origins_lock); 208073dfd078SMikulas Patocka 208173dfd078SMikulas Patocka return must_wait; 208273dfd078SMikulas Patocka } 208373dfd078SMikulas Patocka 208473dfd078SMikulas Patocka /* 20851da177e4SLinus Torvalds * Origin: maps a linear range of a device, with hooks for snapshotting. 20861da177e4SLinus Torvalds */ 20871da177e4SLinus Torvalds 20881da177e4SLinus Torvalds /* 20891da177e4SLinus Torvalds * Construct an origin mapping: <dev_path> 20901da177e4SLinus Torvalds * The context for an origin is merely a 'struct dm_dev *' 20911da177e4SLinus Torvalds * pointing to the real device. 20921da177e4SLinus Torvalds */ 20931da177e4SLinus Torvalds static int origin_ctr(struct dm_target *ti, unsigned int argc, char **argv) 20941da177e4SLinus Torvalds { 20951da177e4SLinus Torvalds int r; 20961da177e4SLinus Torvalds struct dm_dev *dev; 20971da177e4SLinus Torvalds 20981da177e4SLinus Torvalds if (argc != 1) { 209972d94861SAlasdair G Kergon ti->error = "origin: incorrect number of arguments"; 21001da177e4SLinus Torvalds return -EINVAL; 21011da177e4SLinus Torvalds } 21021da177e4SLinus Torvalds 21031da177e4SLinus Torvalds r = dm_get_device(ti, argv[0], 0, ti->len, 21041da177e4SLinus Torvalds dm_table_get_mode(ti->table), &dev); 21051da177e4SLinus Torvalds if (r) { 21061da177e4SLinus Torvalds ti->error = "Cannot get target device"; 21071da177e4SLinus Torvalds return r; 21081da177e4SLinus Torvalds } 21091da177e4SLinus Torvalds 21101da177e4SLinus Torvalds ti->private = dev; 2111494b3ee7SMikulas Patocka ti->num_flush_requests = 1; 2112494b3ee7SMikulas Patocka 21131da177e4SLinus Torvalds return 0; 21141da177e4SLinus Torvalds } 21151da177e4SLinus Torvalds 21161da177e4SLinus Torvalds static void origin_dtr(struct dm_target *ti) 21171da177e4SLinus Torvalds { 2118028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 21191da177e4SLinus Torvalds dm_put_device(ti, dev); 21201da177e4SLinus Torvalds } 21211da177e4SLinus Torvalds 21221da177e4SLinus Torvalds static int origin_map(struct dm_target *ti, struct bio *bio, 21231da177e4SLinus Torvalds union map_info *map_context) 21241da177e4SLinus Torvalds { 2125028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 21261da177e4SLinus Torvalds bio->bi_bdev = dev->bdev; 21271da177e4SLinus Torvalds 2128494b3ee7SMikulas Patocka if (unlikely(bio_empty_barrier(bio))) 2129494b3ee7SMikulas Patocka return DM_MAPIO_REMAPPED; 2130494b3ee7SMikulas Patocka 21311da177e4SLinus Torvalds /* Only tell snapshots if this is a write */ 2132d2a7ad29SKiyoshi Ueda return (bio_rw(bio) == WRITE) ? do_origin(dev, bio) : DM_MAPIO_REMAPPED; 21331da177e4SLinus Torvalds } 21341da177e4SLinus Torvalds 21351da177e4SLinus Torvalds /* 21361da177e4SLinus Torvalds * Set the target "split_io" field to the minimum of all the snapshots' 21371da177e4SLinus Torvalds * chunk sizes. 21381da177e4SLinus Torvalds */ 21391da177e4SLinus Torvalds static void origin_resume(struct dm_target *ti) 21401da177e4SLinus Torvalds { 2141028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 21421da177e4SLinus Torvalds 21431e03f97eSMikulas Patocka ti->split_io = get_origin_minimum_chunksize(dev->bdev); 21441da177e4SLinus Torvalds } 21451da177e4SLinus Torvalds 21461da177e4SLinus Torvalds static int origin_status(struct dm_target *ti, status_type_t type, char *result, 21471da177e4SLinus Torvalds unsigned int maxlen) 21481da177e4SLinus Torvalds { 2149028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 21501da177e4SLinus Torvalds 21511da177e4SLinus Torvalds switch (type) { 21521da177e4SLinus Torvalds case STATUSTYPE_INFO: 21531da177e4SLinus Torvalds result[0] = '\0'; 21541da177e4SLinus Torvalds break; 21551da177e4SLinus Torvalds 21561da177e4SLinus Torvalds case STATUSTYPE_TABLE: 21571da177e4SLinus Torvalds snprintf(result, maxlen, "%s", dev->name); 21581da177e4SLinus Torvalds break; 21591da177e4SLinus Torvalds } 21601da177e4SLinus Torvalds 21611da177e4SLinus Torvalds return 0; 21621da177e4SLinus Torvalds } 21631da177e4SLinus Torvalds 21648811f46cSMike Snitzer static int origin_iterate_devices(struct dm_target *ti, 21658811f46cSMike Snitzer iterate_devices_callout_fn fn, void *data) 21668811f46cSMike Snitzer { 21678811f46cSMike Snitzer struct dm_dev *dev = ti->private; 21688811f46cSMike Snitzer 21698811f46cSMike Snitzer return fn(ti, dev, 0, ti->len, data); 21708811f46cSMike Snitzer } 21718811f46cSMike Snitzer 21721da177e4SLinus Torvalds static struct target_type origin_target = { 21731da177e4SLinus Torvalds .name = "snapshot-origin", 21748811f46cSMike Snitzer .version = {1, 7, 0}, 21751da177e4SLinus Torvalds .module = THIS_MODULE, 21761da177e4SLinus Torvalds .ctr = origin_ctr, 21771da177e4SLinus Torvalds .dtr = origin_dtr, 21781da177e4SLinus Torvalds .map = origin_map, 21791da177e4SLinus Torvalds .resume = origin_resume, 21801da177e4SLinus Torvalds .status = origin_status, 21818811f46cSMike Snitzer .iterate_devices = origin_iterate_devices, 21821da177e4SLinus Torvalds }; 21831da177e4SLinus Torvalds 21841da177e4SLinus Torvalds static struct target_type snapshot_target = { 21851da177e4SLinus Torvalds .name = "snapshot", 2186c26655caSMike Snitzer .version = {1, 9, 0}, 21871da177e4SLinus Torvalds .module = THIS_MODULE, 21881da177e4SLinus Torvalds .ctr = snapshot_ctr, 21891da177e4SLinus Torvalds .dtr = snapshot_dtr, 21901da177e4SLinus Torvalds .map = snapshot_map, 2191cd45daffSMikulas Patocka .end_io = snapshot_end_io, 2192c26655caSMike Snitzer .postsuspend = snapshot_postsuspend, 2193c1f0c183SMike Snitzer .preresume = snapshot_preresume, 21941da177e4SLinus Torvalds .resume = snapshot_resume, 21951da177e4SLinus Torvalds .status = snapshot_status, 21968811f46cSMike Snitzer .iterate_devices = snapshot_iterate_devices, 21971da177e4SLinus Torvalds }; 21981da177e4SLinus Torvalds 2199d698aa45SMikulas Patocka static struct target_type merge_target = { 2200d698aa45SMikulas Patocka .name = dm_snapshot_merge_target_name, 2201d698aa45SMikulas Patocka .version = {1, 0, 0}, 2202d698aa45SMikulas Patocka .module = THIS_MODULE, 2203d698aa45SMikulas Patocka .ctr = snapshot_ctr, 2204d698aa45SMikulas Patocka .dtr = snapshot_dtr, 22053452c2a1SMikulas Patocka .map = snapshot_merge_map, 2206d698aa45SMikulas Patocka .end_io = snapshot_end_io, 22071e03f97eSMikulas Patocka .presuspend = snapshot_merge_presuspend, 2208d698aa45SMikulas Patocka .postsuspend = snapshot_postsuspend, 2209d698aa45SMikulas Patocka .preresume = snapshot_preresume, 22101e03f97eSMikulas Patocka .resume = snapshot_merge_resume, 2211d698aa45SMikulas Patocka .status = snapshot_status, 2212d698aa45SMikulas Patocka .iterate_devices = snapshot_iterate_devices, 2213d698aa45SMikulas Patocka }; 2214d698aa45SMikulas Patocka 22151da177e4SLinus Torvalds static int __init dm_snapshot_init(void) 22161da177e4SLinus Torvalds { 22171da177e4SLinus Torvalds int r; 22181da177e4SLinus Torvalds 22194db6bfe0SAlasdair G Kergon r = dm_exception_store_init(); 22204db6bfe0SAlasdair G Kergon if (r) { 22214db6bfe0SAlasdair G Kergon DMERR("Failed to initialize exception stores"); 22224db6bfe0SAlasdair G Kergon return r; 22234db6bfe0SAlasdair G Kergon } 22244db6bfe0SAlasdair G Kergon 22251da177e4SLinus Torvalds r = dm_register_target(&snapshot_target); 2226d698aa45SMikulas Patocka if (r < 0) { 22271da177e4SLinus Torvalds DMERR("snapshot target register failed %d", r); 2228034a186dSJonathan Brassow goto bad_register_snapshot_target; 22291da177e4SLinus Torvalds } 22301da177e4SLinus Torvalds 22311da177e4SLinus Torvalds r = dm_register_target(&origin_target); 22321da177e4SLinus Torvalds if (r < 0) { 223372d94861SAlasdair G Kergon DMERR("Origin target register failed %d", r); 2234d698aa45SMikulas Patocka goto bad_register_origin_target; 2235d698aa45SMikulas Patocka } 2236d698aa45SMikulas Patocka 2237d698aa45SMikulas Patocka r = dm_register_target(&merge_target); 2238d698aa45SMikulas Patocka if (r < 0) { 2239d698aa45SMikulas Patocka DMERR("Merge target register failed %d", r); 2240d698aa45SMikulas Patocka goto bad_register_merge_target; 22411da177e4SLinus Torvalds } 22421da177e4SLinus Torvalds 22431da177e4SLinus Torvalds r = init_origin_hash(); 22441da177e4SLinus Torvalds if (r) { 22451da177e4SLinus Torvalds DMERR("init_origin_hash failed."); 2246d698aa45SMikulas Patocka goto bad_origin_hash; 22471da177e4SLinus Torvalds } 22481da177e4SLinus Torvalds 22491d4989c8SJon Brassow exception_cache = KMEM_CACHE(dm_exception, 0); 22501da177e4SLinus Torvalds if (!exception_cache) { 22511da177e4SLinus Torvalds DMERR("Couldn't create exception cache."); 22521da177e4SLinus Torvalds r = -ENOMEM; 2253d698aa45SMikulas Patocka goto bad_exception_cache; 22541da177e4SLinus Torvalds } 22551da177e4SLinus Torvalds 2256028867acSAlasdair G Kergon pending_cache = KMEM_CACHE(dm_snap_pending_exception, 0); 22571da177e4SLinus Torvalds if (!pending_cache) { 22581da177e4SLinus Torvalds DMERR("Couldn't create pending cache."); 22591da177e4SLinus Torvalds r = -ENOMEM; 2260d698aa45SMikulas Patocka goto bad_pending_cache; 22611da177e4SLinus Torvalds } 22621da177e4SLinus Torvalds 2263cd45daffSMikulas Patocka tracked_chunk_cache = KMEM_CACHE(dm_snap_tracked_chunk, 0); 2264cd45daffSMikulas Patocka if (!tracked_chunk_cache) { 2265cd45daffSMikulas Patocka DMERR("Couldn't create cache to track chunks in use."); 2266cd45daffSMikulas Patocka r = -ENOMEM; 2267d698aa45SMikulas Patocka goto bad_tracked_chunk_cache; 2268cd45daffSMikulas Patocka } 2269cd45daffSMikulas Patocka 2270ca3a931fSAlasdair G Kergon ksnapd = create_singlethread_workqueue("ksnapd"); 2271ca3a931fSAlasdair G Kergon if (!ksnapd) { 2272ca3a931fSAlasdair G Kergon DMERR("Failed to create ksnapd workqueue."); 2273ca3a931fSAlasdair G Kergon r = -ENOMEM; 227492e86812SMikulas Patocka goto bad_pending_pool; 2275ca3a931fSAlasdair G Kergon } 2276ca3a931fSAlasdair G Kergon 22771da177e4SLinus Torvalds return 0; 22781da177e4SLinus Torvalds 2279cd45daffSMikulas Patocka bad_pending_pool: 2280cd45daffSMikulas Patocka kmem_cache_destroy(tracked_chunk_cache); 2281d698aa45SMikulas Patocka bad_tracked_chunk_cache: 22821da177e4SLinus Torvalds kmem_cache_destroy(pending_cache); 2283d698aa45SMikulas Patocka bad_pending_cache: 22841da177e4SLinus Torvalds kmem_cache_destroy(exception_cache); 2285d698aa45SMikulas Patocka bad_exception_cache: 22861da177e4SLinus Torvalds exit_origin_hash(); 2287d698aa45SMikulas Patocka bad_origin_hash: 2288d698aa45SMikulas Patocka dm_unregister_target(&merge_target); 2289d698aa45SMikulas Patocka bad_register_merge_target: 22901da177e4SLinus Torvalds dm_unregister_target(&origin_target); 2291d698aa45SMikulas Patocka bad_register_origin_target: 22921da177e4SLinus Torvalds dm_unregister_target(&snapshot_target); 2293034a186dSJonathan Brassow bad_register_snapshot_target: 2294034a186dSJonathan Brassow dm_exception_store_exit(); 2295d698aa45SMikulas Patocka 22961da177e4SLinus Torvalds return r; 22971da177e4SLinus Torvalds } 22981da177e4SLinus Torvalds 22991da177e4SLinus Torvalds static void __exit dm_snapshot_exit(void) 23001da177e4SLinus Torvalds { 2301ca3a931fSAlasdair G Kergon destroy_workqueue(ksnapd); 2302ca3a931fSAlasdair G Kergon 230310d3bd09SMikulas Patocka dm_unregister_target(&snapshot_target); 230410d3bd09SMikulas Patocka dm_unregister_target(&origin_target); 2305d698aa45SMikulas Patocka dm_unregister_target(&merge_target); 23061da177e4SLinus Torvalds 23071da177e4SLinus Torvalds exit_origin_hash(); 23081da177e4SLinus Torvalds kmem_cache_destroy(pending_cache); 23091da177e4SLinus Torvalds kmem_cache_destroy(exception_cache); 2310cd45daffSMikulas Patocka kmem_cache_destroy(tracked_chunk_cache); 23114db6bfe0SAlasdair G Kergon 23124db6bfe0SAlasdair G Kergon dm_exception_store_exit(); 23131da177e4SLinus Torvalds } 23141da177e4SLinus Torvalds 23151da177e4SLinus Torvalds /* Module hooks */ 23161da177e4SLinus Torvalds module_init(dm_snapshot_init); 23171da177e4SLinus Torvalds module_exit(dm_snapshot_exit); 23181da177e4SLinus Torvalds 23191da177e4SLinus Torvalds MODULE_DESCRIPTION(DM_NAME " snapshot target"); 23201da177e4SLinus Torvalds MODULE_AUTHOR("Joe Thornber"); 23211da177e4SLinus Torvalds MODULE_LICENSE("GPL"); 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