11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * dm-snapshot.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 2001-2002 Sistina Software (UK) Limited. 51da177e4SLinus Torvalds * 61da177e4SLinus Torvalds * This file is released under the GPL. 71da177e4SLinus Torvalds */ 81da177e4SLinus Torvalds 91da177e4SLinus Torvalds #include <linux/blkdev.h> 101da177e4SLinus Torvalds #include <linux/device-mapper.h> 1190fa1527SMikulas Patocka #include <linux/delay.h> 121da177e4SLinus Torvalds #include <linux/fs.h> 131da177e4SLinus Torvalds #include <linux/init.h> 141da177e4SLinus Torvalds #include <linux/kdev_t.h> 151da177e4SLinus Torvalds #include <linux/list.h> 161da177e4SLinus Torvalds #include <linux/mempool.h> 171da177e4SLinus Torvalds #include <linux/module.h> 181da177e4SLinus Torvalds #include <linux/slab.h> 191da177e4SLinus Torvalds #include <linux/vmalloc.h> 206f3c3f0aSvignesh babu #include <linux/log2.h> 21a765e20eSAlasdair G Kergon #include <linux/dm-kcopyd.h> 221da177e4SLinus Torvalds 23aea53d92SJonathan Brassow #include "dm-exception-store.h" 241da177e4SLinus Torvalds 2572d94861SAlasdair G Kergon #define DM_MSG_PREFIX "snapshots" 2672d94861SAlasdair G Kergon 27d698aa45SMikulas Patocka static const char dm_snapshot_merge_target_name[] = "snapshot-merge"; 28d698aa45SMikulas Patocka 29d698aa45SMikulas Patocka #define dm_target_is_snapshot_merge(ti) \ 30d698aa45SMikulas Patocka ((ti)->type->name == dm_snapshot_merge_target_name) 31d698aa45SMikulas Patocka 321da177e4SLinus Torvalds /* 33cd45daffSMikulas Patocka * The size of the mempool used to track chunks in use. 34cd45daffSMikulas Patocka */ 35cd45daffSMikulas Patocka #define MIN_IOS 256 36cd45daffSMikulas Patocka 37ccc45ea8SJonathan Brassow #define DM_TRACKED_CHUNK_HASH_SIZE 16 38ccc45ea8SJonathan Brassow #define DM_TRACKED_CHUNK_HASH(x) ((unsigned long)(x) & \ 39ccc45ea8SJonathan Brassow (DM_TRACKED_CHUNK_HASH_SIZE - 1)) 40ccc45ea8SJonathan Brassow 41191437a5SJon Brassow struct dm_exception_table { 42ccc45ea8SJonathan Brassow uint32_t hash_mask; 43ccc45ea8SJonathan Brassow unsigned hash_shift; 44ccc45ea8SJonathan Brassow struct list_head *table; 45ccc45ea8SJonathan Brassow }; 46ccc45ea8SJonathan Brassow 47ccc45ea8SJonathan Brassow struct dm_snapshot { 48ccc45ea8SJonathan Brassow struct rw_semaphore lock; 49ccc45ea8SJonathan Brassow 50ccc45ea8SJonathan Brassow struct dm_dev *origin; 51fc56f6fbSMike Snitzer struct dm_dev *cow; 52fc56f6fbSMike Snitzer 53fc56f6fbSMike Snitzer struct dm_target *ti; 54ccc45ea8SJonathan Brassow 55ccc45ea8SJonathan Brassow /* List of snapshots per Origin */ 56ccc45ea8SJonathan Brassow struct list_head list; 57ccc45ea8SJonathan Brassow 58d8ddb1cfSMike Snitzer /* 59d8ddb1cfSMike Snitzer * You can't use a snapshot if this is 0 (e.g. if full). 60d8ddb1cfSMike Snitzer * A snapshot-merge target never clears this. 61d8ddb1cfSMike Snitzer */ 62ccc45ea8SJonathan Brassow int valid; 63ccc45ea8SJonathan Brassow 64ccc45ea8SJonathan Brassow /* Origin writes don't trigger exceptions until this is set */ 65ccc45ea8SJonathan Brassow int active; 66ccc45ea8SJonathan Brassow 67ccc45ea8SJonathan Brassow atomic_t pending_exceptions_count; 68ccc45ea8SJonathan Brassow 69924e600dSMike Snitzer mempool_t *pending_pool; 70924e600dSMike Snitzer 71191437a5SJon Brassow struct dm_exception_table pending; 72191437a5SJon Brassow struct dm_exception_table complete; 73ccc45ea8SJonathan Brassow 74ccc45ea8SJonathan Brassow /* 75ccc45ea8SJonathan Brassow * pe_lock protects all pending_exception operations and access 76ccc45ea8SJonathan Brassow * as well as the snapshot_bios list. 77ccc45ea8SJonathan Brassow */ 78ccc45ea8SJonathan Brassow spinlock_t pe_lock; 79ccc45ea8SJonathan Brassow 80924e600dSMike Snitzer /* Chunks with outstanding reads */ 81924e600dSMike Snitzer spinlock_t tracked_chunk_lock; 82924e600dSMike Snitzer struct hlist_head tracked_chunk_hash[DM_TRACKED_CHUNK_HASH_SIZE]; 83924e600dSMike Snitzer 84ccc45ea8SJonathan Brassow /* The on disk metadata handler */ 85ccc45ea8SJonathan Brassow struct dm_exception_store *store; 86ccc45ea8SJonathan Brassow 87ccc45ea8SJonathan Brassow struct dm_kcopyd_client *kcopyd_client; 88ccc45ea8SJonathan Brassow 89924e600dSMike Snitzer /* Wait for events based on state_bits */ 90924e600dSMike Snitzer unsigned long state_bits; 91924e600dSMike Snitzer 92924e600dSMike Snitzer /* Range of chunks currently being merged. */ 93924e600dSMike Snitzer chunk_t first_merging_chunk; 94924e600dSMike Snitzer int num_merging_chunks; 951e03f97eSMikulas Patocka 96d8ddb1cfSMike Snitzer /* 97d8ddb1cfSMike Snitzer * The merge operation failed if this flag is set. 98d8ddb1cfSMike Snitzer * Failure modes are handled as follows: 99d8ddb1cfSMike Snitzer * - I/O error reading the header 100d8ddb1cfSMike Snitzer * => don't load the target; abort. 101d8ddb1cfSMike Snitzer * - Header does not have "valid" flag set 102d8ddb1cfSMike Snitzer * => use the origin; forget about the snapshot. 103d8ddb1cfSMike Snitzer * - I/O error when reading exceptions 104d8ddb1cfSMike Snitzer * => don't load the target; abort. 105d8ddb1cfSMike Snitzer * (We can't use the intermediate origin state.) 106d8ddb1cfSMike Snitzer * - I/O error while merging 107d8ddb1cfSMike Snitzer * => stop merging; set merge_failed; process I/O normally. 108d8ddb1cfSMike Snitzer */ 109d8ddb1cfSMike Snitzer int merge_failed; 110d8ddb1cfSMike Snitzer 1119fe86254SMikulas Patocka /* 1129fe86254SMikulas Patocka * Incoming bios that overlap with chunks being merged must wait 1139fe86254SMikulas Patocka * for them to be committed. 1149fe86254SMikulas Patocka */ 1159fe86254SMikulas Patocka struct bio_list bios_queued_during_merge; 116ccc45ea8SJonathan Brassow }; 117ccc45ea8SJonathan Brassow 1181e03f97eSMikulas Patocka /* 1191e03f97eSMikulas Patocka * state_bits: 1201e03f97eSMikulas Patocka * RUNNING_MERGE - Merge operation is in progress. 1211e03f97eSMikulas Patocka * SHUTDOWN_MERGE - Set to signal that merge needs to be stopped; 1221e03f97eSMikulas Patocka * cleared afterwards. 1231e03f97eSMikulas Patocka */ 1241e03f97eSMikulas Patocka #define RUNNING_MERGE 0 1251e03f97eSMikulas Patocka #define SHUTDOWN_MERGE 1 1261e03f97eSMikulas Patocka 127df5d2e90SMikulas Patocka DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(snapshot_copy_throttle, 128df5d2e90SMikulas Patocka "A percentage of time allocated for copy on write"); 129df5d2e90SMikulas Patocka 130c2411045SMikulas Patocka struct dm_dev *dm_snap_origin(struct dm_snapshot *s) 131c2411045SMikulas Patocka { 132c2411045SMikulas Patocka return s->origin; 133c2411045SMikulas Patocka } 134c2411045SMikulas Patocka EXPORT_SYMBOL(dm_snap_origin); 135c2411045SMikulas Patocka 136fc56f6fbSMike Snitzer struct dm_dev *dm_snap_cow(struct dm_snapshot *s) 137fc56f6fbSMike Snitzer { 138fc56f6fbSMike Snitzer return s->cow; 139fc56f6fbSMike Snitzer } 140fc56f6fbSMike Snitzer EXPORT_SYMBOL(dm_snap_cow); 141fc56f6fbSMike Snitzer 142ccc45ea8SJonathan Brassow static sector_t chunk_to_sector(struct dm_exception_store *store, 143ccc45ea8SJonathan Brassow chunk_t chunk) 144ccc45ea8SJonathan Brassow { 145ccc45ea8SJonathan Brassow return chunk << store->chunk_shift; 146ccc45ea8SJonathan Brassow } 147ccc45ea8SJonathan Brassow 148ccc45ea8SJonathan Brassow static int bdev_equal(struct block_device *lhs, struct block_device *rhs) 149ccc45ea8SJonathan Brassow { 150ccc45ea8SJonathan Brassow /* 151ccc45ea8SJonathan Brassow * There is only ever one instance of a particular block 152ccc45ea8SJonathan Brassow * device so we can compare pointers safely. 153ccc45ea8SJonathan Brassow */ 154ccc45ea8SJonathan Brassow return lhs == rhs; 155ccc45ea8SJonathan Brassow } 156ccc45ea8SJonathan Brassow 157028867acSAlasdair G Kergon struct dm_snap_pending_exception { 1581d4989c8SJon Brassow struct dm_exception e; 1591da177e4SLinus Torvalds 1601da177e4SLinus Torvalds /* 1611da177e4SLinus Torvalds * Origin buffers waiting for this to complete are held 1621da177e4SLinus Torvalds * in a bio list 1631da177e4SLinus Torvalds */ 1641da177e4SLinus Torvalds struct bio_list origin_bios; 1651da177e4SLinus Torvalds struct bio_list snapshot_bios; 1661da177e4SLinus Torvalds 1671da177e4SLinus Torvalds /* Pointer back to snapshot context */ 1681da177e4SLinus Torvalds struct dm_snapshot *snap; 1691da177e4SLinus Torvalds 1701da177e4SLinus Torvalds /* 1711da177e4SLinus Torvalds * 1 indicates the exception has already been sent to 1721da177e4SLinus Torvalds * kcopyd. 1731da177e4SLinus Torvalds */ 1741da177e4SLinus Torvalds int started; 175a6e50b40SMikulas Patocka 176a6e50b40SMikulas Patocka /* 177a6e50b40SMikulas Patocka * For writing a complete chunk, bypassing the copy. 178a6e50b40SMikulas Patocka */ 179a6e50b40SMikulas Patocka struct bio *full_bio; 180a6e50b40SMikulas Patocka bio_end_io_t *full_bio_end_io; 181a6e50b40SMikulas Patocka void *full_bio_private; 1821da177e4SLinus Torvalds }; 1831da177e4SLinus Torvalds 1841da177e4SLinus Torvalds /* 1851da177e4SLinus Torvalds * Hash table mapping origin volumes to lists of snapshots and 1861da177e4SLinus Torvalds * a lock to protect it 1871da177e4SLinus Torvalds */ 188e18b890bSChristoph Lameter static struct kmem_cache *exception_cache; 189e18b890bSChristoph Lameter static struct kmem_cache *pending_cache; 1901da177e4SLinus Torvalds 191cd45daffSMikulas Patocka struct dm_snap_tracked_chunk { 192cd45daffSMikulas Patocka struct hlist_node node; 193cd45daffSMikulas Patocka chunk_t chunk; 194cd45daffSMikulas Patocka }; 195cd45daffSMikulas Patocka 196ee18026aSMikulas Patocka static void init_tracked_chunk(struct bio *bio) 197ee18026aSMikulas Patocka { 198ee18026aSMikulas Patocka struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk)); 199ee18026aSMikulas Patocka INIT_HLIST_NODE(&c->node); 200ee18026aSMikulas Patocka } 201ee18026aSMikulas Patocka 202ee18026aSMikulas Patocka static bool is_bio_tracked(struct bio *bio) 203ee18026aSMikulas Patocka { 204ee18026aSMikulas Patocka struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk)); 205ee18026aSMikulas Patocka return !hlist_unhashed(&c->node); 206ee18026aSMikulas Patocka } 207ee18026aSMikulas Patocka 208ee18026aSMikulas Patocka static void track_chunk(struct dm_snapshot *s, struct bio *bio, chunk_t chunk) 209cd45daffSMikulas Patocka { 21042bc954fSMikulas Patocka struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk)); 211cd45daffSMikulas Patocka 212cd45daffSMikulas Patocka c->chunk = chunk; 213cd45daffSMikulas Patocka 2149aa0c0e6SMikulas Patocka spin_lock_irq(&s->tracked_chunk_lock); 215cd45daffSMikulas Patocka hlist_add_head(&c->node, 216cd45daffSMikulas Patocka &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)]); 2179aa0c0e6SMikulas Patocka spin_unlock_irq(&s->tracked_chunk_lock); 218cd45daffSMikulas Patocka } 219cd45daffSMikulas Patocka 220ee18026aSMikulas Patocka static void stop_tracking_chunk(struct dm_snapshot *s, struct bio *bio) 221cd45daffSMikulas Patocka { 222ee18026aSMikulas Patocka struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk)); 223cd45daffSMikulas Patocka unsigned long flags; 224cd45daffSMikulas Patocka 225cd45daffSMikulas Patocka spin_lock_irqsave(&s->tracked_chunk_lock, flags); 226cd45daffSMikulas Patocka hlist_del(&c->node); 227cd45daffSMikulas Patocka spin_unlock_irqrestore(&s->tracked_chunk_lock, flags); 228cd45daffSMikulas Patocka } 229cd45daffSMikulas Patocka 230a8d41b59SMikulas Patocka static int __chunk_is_tracked(struct dm_snapshot *s, chunk_t chunk) 231a8d41b59SMikulas Patocka { 232a8d41b59SMikulas Patocka struct dm_snap_tracked_chunk *c; 233a8d41b59SMikulas Patocka int found = 0; 234a8d41b59SMikulas Patocka 235a8d41b59SMikulas Patocka spin_lock_irq(&s->tracked_chunk_lock); 236a8d41b59SMikulas Patocka 237b67bfe0dSSasha Levin hlist_for_each_entry(c, 238a8d41b59SMikulas Patocka &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)], node) { 239a8d41b59SMikulas Patocka if (c->chunk == chunk) { 240a8d41b59SMikulas Patocka found = 1; 241a8d41b59SMikulas Patocka break; 242a8d41b59SMikulas Patocka } 243a8d41b59SMikulas Patocka } 244a8d41b59SMikulas Patocka 245a8d41b59SMikulas Patocka spin_unlock_irq(&s->tracked_chunk_lock); 246a8d41b59SMikulas Patocka 247a8d41b59SMikulas Patocka return found; 248a8d41b59SMikulas Patocka } 249a8d41b59SMikulas Patocka 2501da177e4SLinus Torvalds /* 251615d1eb9SMike Snitzer * This conflicting I/O is extremely improbable in the caller, 252615d1eb9SMike Snitzer * so msleep(1) is sufficient and there is no need for a wait queue. 253615d1eb9SMike Snitzer */ 254615d1eb9SMike Snitzer static void __check_for_conflicting_io(struct dm_snapshot *s, chunk_t chunk) 255615d1eb9SMike Snitzer { 256615d1eb9SMike Snitzer while (__chunk_is_tracked(s, chunk)) 257615d1eb9SMike Snitzer msleep(1); 258615d1eb9SMike Snitzer } 259615d1eb9SMike Snitzer 260615d1eb9SMike Snitzer /* 2611da177e4SLinus Torvalds * One of these per registered origin, held in the snapshot_origins hash 2621da177e4SLinus Torvalds */ 2631da177e4SLinus Torvalds struct origin { 2641da177e4SLinus Torvalds /* The origin device */ 2651da177e4SLinus Torvalds struct block_device *bdev; 2661da177e4SLinus Torvalds 2671da177e4SLinus Torvalds struct list_head hash_list; 2681da177e4SLinus Torvalds 2691da177e4SLinus Torvalds /* List of snapshots for this origin */ 2701da177e4SLinus Torvalds struct list_head snapshots; 2711da177e4SLinus Torvalds }; 2721da177e4SLinus Torvalds 2731da177e4SLinus Torvalds /* 2741da177e4SLinus Torvalds * Size of the hash table for origin volumes. If we make this 2751da177e4SLinus Torvalds * the size of the minors list then it should be nearly perfect 2761da177e4SLinus Torvalds */ 2771da177e4SLinus Torvalds #define ORIGIN_HASH_SIZE 256 2781da177e4SLinus Torvalds #define ORIGIN_MASK 0xFF 2791da177e4SLinus Torvalds static struct list_head *_origins; 2801da177e4SLinus Torvalds static struct rw_semaphore _origins_lock; 2811da177e4SLinus Torvalds 28273dfd078SMikulas Patocka static DECLARE_WAIT_QUEUE_HEAD(_pending_exceptions_done); 28373dfd078SMikulas Patocka static DEFINE_SPINLOCK(_pending_exceptions_done_spinlock); 28473dfd078SMikulas Patocka static uint64_t _pending_exceptions_done_count; 28573dfd078SMikulas Patocka 2861da177e4SLinus Torvalds static int init_origin_hash(void) 2871da177e4SLinus Torvalds { 2881da177e4SLinus Torvalds int i; 2891da177e4SLinus Torvalds 2901da177e4SLinus Torvalds _origins = kmalloc(ORIGIN_HASH_SIZE * sizeof(struct list_head), 2911da177e4SLinus Torvalds GFP_KERNEL); 2921da177e4SLinus Torvalds if (!_origins) { 29372d94861SAlasdair G Kergon DMERR("unable to allocate memory"); 2941da177e4SLinus Torvalds return -ENOMEM; 2951da177e4SLinus Torvalds } 2961da177e4SLinus Torvalds 2971da177e4SLinus Torvalds for (i = 0; i < ORIGIN_HASH_SIZE; i++) 2981da177e4SLinus Torvalds INIT_LIST_HEAD(_origins + i); 2991da177e4SLinus Torvalds init_rwsem(&_origins_lock); 3001da177e4SLinus Torvalds 3011da177e4SLinus Torvalds return 0; 3021da177e4SLinus Torvalds } 3031da177e4SLinus Torvalds 3041da177e4SLinus Torvalds static void exit_origin_hash(void) 3051da177e4SLinus Torvalds { 3061da177e4SLinus Torvalds kfree(_origins); 3071da177e4SLinus Torvalds } 3081da177e4SLinus Torvalds 309028867acSAlasdair G Kergon static unsigned origin_hash(struct block_device *bdev) 3101da177e4SLinus Torvalds { 3111da177e4SLinus Torvalds return bdev->bd_dev & ORIGIN_MASK; 3121da177e4SLinus Torvalds } 3131da177e4SLinus Torvalds 3141da177e4SLinus Torvalds static struct origin *__lookup_origin(struct block_device *origin) 3151da177e4SLinus Torvalds { 3161da177e4SLinus Torvalds struct list_head *ol; 3171da177e4SLinus Torvalds struct origin *o; 3181da177e4SLinus Torvalds 3191da177e4SLinus Torvalds ol = &_origins[origin_hash(origin)]; 3201da177e4SLinus Torvalds list_for_each_entry (o, ol, hash_list) 3211da177e4SLinus Torvalds if (bdev_equal(o->bdev, origin)) 3221da177e4SLinus Torvalds return o; 3231da177e4SLinus Torvalds 3241da177e4SLinus Torvalds return NULL; 3251da177e4SLinus Torvalds } 3261da177e4SLinus Torvalds 3271da177e4SLinus Torvalds static void __insert_origin(struct origin *o) 3281da177e4SLinus Torvalds { 3291da177e4SLinus Torvalds struct list_head *sl = &_origins[origin_hash(o->bdev)]; 3301da177e4SLinus Torvalds list_add_tail(&o->hash_list, sl); 3311da177e4SLinus Torvalds } 3321da177e4SLinus Torvalds 3331da177e4SLinus Torvalds /* 334c1f0c183SMike Snitzer * _origins_lock must be held when calling this function. 335c1f0c183SMike Snitzer * Returns number of snapshots registered using the supplied cow device, plus: 336c1f0c183SMike Snitzer * snap_src - a snapshot suitable for use as a source of exception handover 337c1f0c183SMike Snitzer * snap_dest - a snapshot capable of receiving exception handover. 3389d3b15c4SMikulas Patocka * snap_merge - an existing snapshot-merge target linked to the same origin. 3399d3b15c4SMikulas Patocka * There can be at most one snapshot-merge target. The parameter is optional. 340c1f0c183SMike Snitzer * 3419d3b15c4SMikulas Patocka * Possible return values and states of snap_src and snap_dest. 342c1f0c183SMike Snitzer * 0: NULL, NULL - first new snapshot 343c1f0c183SMike Snitzer * 1: snap_src, NULL - normal snapshot 344c1f0c183SMike Snitzer * 2: snap_src, snap_dest - waiting for handover 345c1f0c183SMike Snitzer * 2: snap_src, NULL - handed over, waiting for old to be deleted 346c1f0c183SMike Snitzer * 1: NULL, snap_dest - source got destroyed without handover 347c1f0c183SMike Snitzer */ 348c1f0c183SMike Snitzer static int __find_snapshots_sharing_cow(struct dm_snapshot *snap, 349c1f0c183SMike Snitzer struct dm_snapshot **snap_src, 3509d3b15c4SMikulas Patocka struct dm_snapshot **snap_dest, 3519d3b15c4SMikulas Patocka struct dm_snapshot **snap_merge) 352c1f0c183SMike Snitzer { 353c1f0c183SMike Snitzer struct dm_snapshot *s; 354c1f0c183SMike Snitzer struct origin *o; 355c1f0c183SMike Snitzer int count = 0; 356c1f0c183SMike Snitzer int active; 357c1f0c183SMike Snitzer 358c1f0c183SMike Snitzer o = __lookup_origin(snap->origin->bdev); 359c1f0c183SMike Snitzer if (!o) 360c1f0c183SMike Snitzer goto out; 361c1f0c183SMike Snitzer 362c1f0c183SMike Snitzer list_for_each_entry(s, &o->snapshots, list) { 3639d3b15c4SMikulas Patocka if (dm_target_is_snapshot_merge(s->ti) && snap_merge) 3649d3b15c4SMikulas Patocka *snap_merge = s; 365c1f0c183SMike Snitzer if (!bdev_equal(s->cow->bdev, snap->cow->bdev)) 366c1f0c183SMike Snitzer continue; 367c1f0c183SMike Snitzer 368c1f0c183SMike Snitzer down_read(&s->lock); 369c1f0c183SMike Snitzer active = s->active; 370c1f0c183SMike Snitzer up_read(&s->lock); 371c1f0c183SMike Snitzer 372c1f0c183SMike Snitzer if (active) { 373c1f0c183SMike Snitzer if (snap_src) 374c1f0c183SMike Snitzer *snap_src = s; 375c1f0c183SMike Snitzer } else if (snap_dest) 376c1f0c183SMike Snitzer *snap_dest = s; 377c1f0c183SMike Snitzer 378c1f0c183SMike Snitzer count++; 379c1f0c183SMike Snitzer } 380c1f0c183SMike Snitzer 381c1f0c183SMike Snitzer out: 382c1f0c183SMike Snitzer return count; 383c1f0c183SMike Snitzer } 384c1f0c183SMike Snitzer 385c1f0c183SMike Snitzer /* 386c1f0c183SMike Snitzer * On success, returns 1 if this snapshot is a handover destination, 387c1f0c183SMike Snitzer * otherwise returns 0. 388c1f0c183SMike Snitzer */ 389c1f0c183SMike Snitzer static int __validate_exception_handover(struct dm_snapshot *snap) 390c1f0c183SMike Snitzer { 391c1f0c183SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 3929d3b15c4SMikulas Patocka struct dm_snapshot *snap_merge = NULL; 393c1f0c183SMike Snitzer 394c1f0c183SMike Snitzer /* Does snapshot need exceptions handed over to it? */ 3959d3b15c4SMikulas Patocka if ((__find_snapshots_sharing_cow(snap, &snap_src, &snap_dest, 3969d3b15c4SMikulas Patocka &snap_merge) == 2) || 397c1f0c183SMike Snitzer snap_dest) { 398c1f0c183SMike Snitzer snap->ti->error = "Snapshot cow pairing for exception " 399c1f0c183SMike Snitzer "table handover failed"; 400c1f0c183SMike Snitzer return -EINVAL; 401c1f0c183SMike Snitzer } 402c1f0c183SMike Snitzer 403c1f0c183SMike Snitzer /* 404c1f0c183SMike Snitzer * If no snap_src was found, snap cannot become a handover 405c1f0c183SMike Snitzer * destination. 406c1f0c183SMike Snitzer */ 407c1f0c183SMike Snitzer if (!snap_src) 408c1f0c183SMike Snitzer return 0; 409c1f0c183SMike Snitzer 4109d3b15c4SMikulas Patocka /* 4119d3b15c4SMikulas Patocka * Non-snapshot-merge handover? 4129d3b15c4SMikulas Patocka */ 4139d3b15c4SMikulas Patocka if (!dm_target_is_snapshot_merge(snap->ti)) 4149d3b15c4SMikulas Patocka return 1; 4159d3b15c4SMikulas Patocka 4169d3b15c4SMikulas Patocka /* 4179d3b15c4SMikulas Patocka * Do not allow more than one merging snapshot. 4189d3b15c4SMikulas Patocka */ 4199d3b15c4SMikulas Patocka if (snap_merge) { 4209d3b15c4SMikulas Patocka snap->ti->error = "A snapshot is already merging."; 4219d3b15c4SMikulas Patocka return -EINVAL; 4229d3b15c4SMikulas Patocka } 4239d3b15c4SMikulas Patocka 4241e03f97eSMikulas Patocka if (!snap_src->store->type->prepare_merge || 4251e03f97eSMikulas Patocka !snap_src->store->type->commit_merge) { 4261e03f97eSMikulas Patocka snap->ti->error = "Snapshot exception store does not " 4271e03f97eSMikulas Patocka "support snapshot-merge."; 4281e03f97eSMikulas Patocka return -EINVAL; 4291e03f97eSMikulas Patocka } 4301e03f97eSMikulas Patocka 431c1f0c183SMike Snitzer return 1; 432c1f0c183SMike Snitzer } 433c1f0c183SMike Snitzer 434c1f0c183SMike Snitzer static void __insert_snapshot(struct origin *o, struct dm_snapshot *s) 435c1f0c183SMike Snitzer { 436c1f0c183SMike Snitzer struct dm_snapshot *l; 437c1f0c183SMike Snitzer 438c1f0c183SMike Snitzer /* Sort the list according to chunk size, largest-first smallest-last */ 439c1f0c183SMike Snitzer list_for_each_entry(l, &o->snapshots, list) 440c1f0c183SMike Snitzer if (l->store->chunk_size < s->store->chunk_size) 441c1f0c183SMike Snitzer break; 442c1f0c183SMike Snitzer list_add_tail(&s->list, &l->list); 443c1f0c183SMike Snitzer } 444c1f0c183SMike Snitzer 445c1f0c183SMike Snitzer /* 4461da177e4SLinus Torvalds * Make a note of the snapshot and its origin so we can look it 4471da177e4SLinus Torvalds * up when the origin has a write on it. 448c1f0c183SMike Snitzer * 449c1f0c183SMike Snitzer * Also validate snapshot exception store handovers. 450c1f0c183SMike Snitzer * On success, returns 1 if this registration is a handover destination, 451c1f0c183SMike Snitzer * otherwise returns 0. 4521da177e4SLinus Torvalds */ 4531da177e4SLinus Torvalds static int register_snapshot(struct dm_snapshot *snap) 4541da177e4SLinus Torvalds { 455c1f0c183SMike Snitzer struct origin *o, *new_o = NULL; 4561da177e4SLinus Torvalds struct block_device *bdev = snap->origin->bdev; 457c1f0c183SMike Snitzer int r = 0; 4581da177e4SLinus Torvalds 45960c856c8SMikulas Patocka new_o = kmalloc(sizeof(*new_o), GFP_KERNEL); 46060c856c8SMikulas Patocka if (!new_o) 46160c856c8SMikulas Patocka return -ENOMEM; 46260c856c8SMikulas Patocka 4631da177e4SLinus Torvalds down_write(&_origins_lock); 4641da177e4SLinus Torvalds 465c1f0c183SMike Snitzer r = __validate_exception_handover(snap); 466c1f0c183SMike Snitzer if (r < 0) { 467c1f0c183SMike Snitzer kfree(new_o); 468c1f0c183SMike Snitzer goto out; 469c1f0c183SMike Snitzer } 470c1f0c183SMike Snitzer 471c1f0c183SMike Snitzer o = __lookup_origin(bdev); 47260c856c8SMikulas Patocka if (o) 47360c856c8SMikulas Patocka kfree(new_o); 47460c856c8SMikulas Patocka else { 4751da177e4SLinus Torvalds /* New origin */ 47660c856c8SMikulas Patocka o = new_o; 4771da177e4SLinus Torvalds 4781da177e4SLinus Torvalds /* Initialise the struct */ 4791da177e4SLinus Torvalds INIT_LIST_HEAD(&o->snapshots); 4801da177e4SLinus Torvalds o->bdev = bdev; 4811da177e4SLinus Torvalds 4821da177e4SLinus Torvalds __insert_origin(o); 4831da177e4SLinus Torvalds } 4841da177e4SLinus Torvalds 485c1f0c183SMike Snitzer __insert_snapshot(o, snap); 486c1f0c183SMike Snitzer 487c1f0c183SMike Snitzer out: 488c1f0c183SMike Snitzer up_write(&_origins_lock); 489c1f0c183SMike Snitzer 490c1f0c183SMike Snitzer return r; 491c1f0c183SMike Snitzer } 492c1f0c183SMike Snitzer 493c1f0c183SMike Snitzer /* 494c1f0c183SMike Snitzer * Move snapshot to correct place in list according to chunk size. 495c1f0c183SMike Snitzer */ 496c1f0c183SMike Snitzer static void reregister_snapshot(struct dm_snapshot *s) 497c1f0c183SMike Snitzer { 498c1f0c183SMike Snitzer struct block_device *bdev = s->origin->bdev; 499c1f0c183SMike Snitzer 500c1f0c183SMike Snitzer down_write(&_origins_lock); 501c1f0c183SMike Snitzer 502c1f0c183SMike Snitzer list_del(&s->list); 503c1f0c183SMike Snitzer __insert_snapshot(__lookup_origin(bdev), s); 5041da177e4SLinus Torvalds 5051da177e4SLinus Torvalds up_write(&_origins_lock); 5061da177e4SLinus Torvalds } 5071da177e4SLinus Torvalds 5081da177e4SLinus Torvalds static void unregister_snapshot(struct dm_snapshot *s) 5091da177e4SLinus Torvalds { 5101da177e4SLinus Torvalds struct origin *o; 5111da177e4SLinus Torvalds 5121da177e4SLinus Torvalds down_write(&_origins_lock); 5131da177e4SLinus Torvalds o = __lookup_origin(s->origin->bdev); 5141da177e4SLinus Torvalds 5151da177e4SLinus Torvalds list_del(&s->list); 516c1f0c183SMike Snitzer if (o && list_empty(&o->snapshots)) { 5171da177e4SLinus Torvalds list_del(&o->hash_list); 5181da177e4SLinus Torvalds kfree(o); 5191da177e4SLinus Torvalds } 5201da177e4SLinus Torvalds 5211da177e4SLinus Torvalds up_write(&_origins_lock); 5221da177e4SLinus Torvalds } 5231da177e4SLinus Torvalds 5241da177e4SLinus Torvalds /* 5251da177e4SLinus Torvalds * Implementation of the exception hash tables. 526d74f81f8SMilan Broz * The lowest hash_shift bits of the chunk number are ignored, allowing 527d74f81f8SMilan Broz * some consecutive chunks to be grouped together. 5281da177e4SLinus Torvalds */ 5293510cb94SJon Brassow static int dm_exception_table_init(struct dm_exception_table *et, 5303510cb94SJon Brassow uint32_t size, unsigned hash_shift) 5311da177e4SLinus Torvalds { 5321da177e4SLinus Torvalds unsigned int i; 5331da177e4SLinus Torvalds 534d74f81f8SMilan Broz et->hash_shift = hash_shift; 5351da177e4SLinus Torvalds et->hash_mask = size - 1; 5361da177e4SLinus Torvalds et->table = dm_vcalloc(size, sizeof(struct list_head)); 5371da177e4SLinus Torvalds if (!et->table) 5381da177e4SLinus Torvalds return -ENOMEM; 5391da177e4SLinus Torvalds 5401da177e4SLinus Torvalds for (i = 0; i < size; i++) 5411da177e4SLinus Torvalds INIT_LIST_HEAD(et->table + i); 5421da177e4SLinus Torvalds 5431da177e4SLinus Torvalds return 0; 5441da177e4SLinus Torvalds } 5451da177e4SLinus Torvalds 5463510cb94SJon Brassow static void dm_exception_table_exit(struct dm_exception_table *et, 547191437a5SJon Brassow struct kmem_cache *mem) 5481da177e4SLinus Torvalds { 5491da177e4SLinus Torvalds struct list_head *slot; 5501d4989c8SJon Brassow struct dm_exception *ex, *next; 5511da177e4SLinus Torvalds int i, size; 5521da177e4SLinus Torvalds 5531da177e4SLinus Torvalds size = et->hash_mask + 1; 5541da177e4SLinus Torvalds for (i = 0; i < size; i++) { 5551da177e4SLinus Torvalds slot = et->table + i; 5561da177e4SLinus Torvalds 5571da177e4SLinus Torvalds list_for_each_entry_safe (ex, next, slot, hash_list) 5581da177e4SLinus Torvalds kmem_cache_free(mem, ex); 5591da177e4SLinus Torvalds } 5601da177e4SLinus Torvalds 5611da177e4SLinus Torvalds vfree(et->table); 5621da177e4SLinus Torvalds } 5631da177e4SLinus Torvalds 564191437a5SJon Brassow static uint32_t exception_hash(struct dm_exception_table *et, chunk_t chunk) 5651da177e4SLinus Torvalds { 566d74f81f8SMilan Broz return (chunk >> et->hash_shift) & et->hash_mask; 5671da177e4SLinus Torvalds } 5681da177e4SLinus Torvalds 5693510cb94SJon Brassow static void dm_remove_exception(struct dm_exception *e) 5701da177e4SLinus Torvalds { 5711da177e4SLinus Torvalds list_del(&e->hash_list); 5721da177e4SLinus Torvalds } 5731da177e4SLinus Torvalds 5741da177e4SLinus Torvalds /* 5751da177e4SLinus Torvalds * Return the exception data for a sector, or NULL if not 5761da177e4SLinus Torvalds * remapped. 5771da177e4SLinus Torvalds */ 5783510cb94SJon Brassow static struct dm_exception *dm_lookup_exception(struct dm_exception_table *et, 5791da177e4SLinus Torvalds chunk_t chunk) 5801da177e4SLinus Torvalds { 5811da177e4SLinus Torvalds struct list_head *slot; 5821d4989c8SJon Brassow struct dm_exception *e; 5831da177e4SLinus Torvalds 5841da177e4SLinus Torvalds slot = &et->table[exception_hash(et, chunk)]; 5851da177e4SLinus Torvalds list_for_each_entry (e, slot, hash_list) 586d74f81f8SMilan Broz if (chunk >= e->old_chunk && 587d74f81f8SMilan Broz chunk <= e->old_chunk + dm_consecutive_chunk_count(e)) 5881da177e4SLinus Torvalds return e; 5891da177e4SLinus Torvalds 5901da177e4SLinus Torvalds return NULL; 5911da177e4SLinus Torvalds } 5921da177e4SLinus Torvalds 5933510cb94SJon Brassow static struct dm_exception *alloc_completed_exception(void) 5941da177e4SLinus Torvalds { 5951d4989c8SJon Brassow struct dm_exception *e; 5961da177e4SLinus Torvalds 5971da177e4SLinus Torvalds e = kmem_cache_alloc(exception_cache, GFP_NOIO); 5981da177e4SLinus Torvalds if (!e) 5991da177e4SLinus Torvalds e = kmem_cache_alloc(exception_cache, GFP_ATOMIC); 6001da177e4SLinus Torvalds 6011da177e4SLinus Torvalds return e; 6021da177e4SLinus Torvalds } 6031da177e4SLinus Torvalds 6043510cb94SJon Brassow static void free_completed_exception(struct dm_exception *e) 6051da177e4SLinus Torvalds { 6061da177e4SLinus Torvalds kmem_cache_free(exception_cache, e); 6071da177e4SLinus Torvalds } 6081da177e4SLinus Torvalds 60992e86812SMikulas Patocka static struct dm_snap_pending_exception *alloc_pending_exception(struct dm_snapshot *s) 6101da177e4SLinus Torvalds { 61192e86812SMikulas Patocka struct dm_snap_pending_exception *pe = mempool_alloc(s->pending_pool, 61292e86812SMikulas Patocka GFP_NOIO); 61392e86812SMikulas Patocka 614879129d2SMikulas Patocka atomic_inc(&s->pending_exceptions_count); 61592e86812SMikulas Patocka pe->snap = s; 61692e86812SMikulas Patocka 61792e86812SMikulas Patocka return pe; 6181da177e4SLinus Torvalds } 6191da177e4SLinus Torvalds 620028867acSAlasdair G Kergon static void free_pending_exception(struct dm_snap_pending_exception *pe) 6211da177e4SLinus Torvalds { 622879129d2SMikulas Patocka struct dm_snapshot *s = pe->snap; 623879129d2SMikulas Patocka 624879129d2SMikulas Patocka mempool_free(pe, s->pending_pool); 625879129d2SMikulas Patocka smp_mb__before_atomic_dec(); 626879129d2SMikulas Patocka atomic_dec(&s->pending_exceptions_count); 6271da177e4SLinus Torvalds } 6281da177e4SLinus Torvalds 6293510cb94SJon Brassow static void dm_insert_exception(struct dm_exception_table *eh, 6301d4989c8SJon Brassow struct dm_exception *new_e) 631d74f81f8SMilan Broz { 632d74f81f8SMilan Broz struct list_head *l; 6331d4989c8SJon Brassow struct dm_exception *e = NULL; 634d74f81f8SMilan Broz 635d74f81f8SMilan Broz l = &eh->table[exception_hash(eh, new_e->old_chunk)]; 636d74f81f8SMilan Broz 637d74f81f8SMilan Broz /* Add immediately if this table doesn't support consecutive chunks */ 638d74f81f8SMilan Broz if (!eh->hash_shift) 639d74f81f8SMilan Broz goto out; 640d74f81f8SMilan Broz 641d74f81f8SMilan Broz /* List is ordered by old_chunk */ 642d74f81f8SMilan Broz list_for_each_entry_reverse(e, l, hash_list) { 643d74f81f8SMilan Broz /* Insert after an existing chunk? */ 644d74f81f8SMilan Broz if (new_e->old_chunk == (e->old_chunk + 645d74f81f8SMilan Broz dm_consecutive_chunk_count(e) + 1) && 646d74f81f8SMilan Broz new_e->new_chunk == (dm_chunk_number(e->new_chunk) + 647d74f81f8SMilan Broz dm_consecutive_chunk_count(e) + 1)) { 648d74f81f8SMilan Broz dm_consecutive_chunk_count_inc(e); 6493510cb94SJon Brassow free_completed_exception(new_e); 650d74f81f8SMilan Broz return; 651d74f81f8SMilan Broz } 652d74f81f8SMilan Broz 653d74f81f8SMilan Broz /* Insert before an existing chunk? */ 654d74f81f8SMilan Broz if (new_e->old_chunk == (e->old_chunk - 1) && 655d74f81f8SMilan Broz new_e->new_chunk == (dm_chunk_number(e->new_chunk) - 1)) { 656d74f81f8SMilan Broz dm_consecutive_chunk_count_inc(e); 657d74f81f8SMilan Broz e->old_chunk--; 658d74f81f8SMilan Broz e->new_chunk--; 6593510cb94SJon Brassow free_completed_exception(new_e); 660d74f81f8SMilan Broz return; 661d74f81f8SMilan Broz } 662d74f81f8SMilan Broz 663d74f81f8SMilan Broz if (new_e->old_chunk > e->old_chunk) 664d74f81f8SMilan Broz break; 665d74f81f8SMilan Broz } 666d74f81f8SMilan Broz 667d74f81f8SMilan Broz out: 668d74f81f8SMilan Broz list_add(&new_e->hash_list, e ? &e->hash_list : l); 669d74f81f8SMilan Broz } 670d74f81f8SMilan Broz 671a159c1acSJonathan Brassow /* 672a159c1acSJonathan Brassow * Callback used by the exception stores to load exceptions when 673a159c1acSJonathan Brassow * initialising. 674a159c1acSJonathan Brassow */ 675a159c1acSJonathan Brassow static int dm_add_exception(void *context, chunk_t old, chunk_t new) 6761da177e4SLinus Torvalds { 677a159c1acSJonathan Brassow struct dm_snapshot *s = context; 6781d4989c8SJon Brassow struct dm_exception *e; 6791da177e4SLinus Torvalds 6803510cb94SJon Brassow e = alloc_completed_exception(); 6811da177e4SLinus Torvalds if (!e) 6821da177e4SLinus Torvalds return -ENOMEM; 6831da177e4SLinus Torvalds 6841da177e4SLinus Torvalds e->old_chunk = old; 685d74f81f8SMilan Broz 686d74f81f8SMilan Broz /* Consecutive_count is implicitly initialised to zero */ 6871da177e4SLinus Torvalds e->new_chunk = new; 688d74f81f8SMilan Broz 6893510cb94SJon Brassow dm_insert_exception(&s->complete, e); 690d74f81f8SMilan Broz 6911da177e4SLinus Torvalds return 0; 6921da177e4SLinus Torvalds } 6931da177e4SLinus Torvalds 6947e201b35SMikulas Patocka /* 6957e201b35SMikulas Patocka * Return a minimum chunk size of all snapshots that have the specified origin. 6967e201b35SMikulas Patocka * Return zero if the origin has no snapshots. 6977e201b35SMikulas Patocka */ 698542f9038SMike Snitzer static uint32_t __minimum_chunk_size(struct origin *o) 6997e201b35SMikulas Patocka { 7007e201b35SMikulas Patocka struct dm_snapshot *snap; 7017e201b35SMikulas Patocka unsigned chunk_size = 0; 7027e201b35SMikulas Patocka 7037e201b35SMikulas Patocka if (o) 7047e201b35SMikulas Patocka list_for_each_entry(snap, &o->snapshots, list) 7057e201b35SMikulas Patocka chunk_size = min_not_zero(chunk_size, 7067e201b35SMikulas Patocka snap->store->chunk_size); 7077e201b35SMikulas Patocka 708542f9038SMike Snitzer return (uint32_t) chunk_size; 7097e201b35SMikulas Patocka } 7107e201b35SMikulas Patocka 7111da177e4SLinus Torvalds /* 7121da177e4SLinus Torvalds * Hard coded magic. 7131da177e4SLinus Torvalds */ 7141da177e4SLinus Torvalds static int calc_max_buckets(void) 7151da177e4SLinus Torvalds { 7161da177e4SLinus Torvalds /* use a fixed size of 2MB */ 7171da177e4SLinus Torvalds unsigned long mem = 2 * 1024 * 1024; 7181da177e4SLinus Torvalds mem /= sizeof(struct list_head); 7191da177e4SLinus Torvalds 7201da177e4SLinus Torvalds return mem; 7211da177e4SLinus Torvalds } 7221da177e4SLinus Torvalds 7231da177e4SLinus Torvalds /* 7241da177e4SLinus Torvalds * Allocate room for a suitable hash table. 7251da177e4SLinus Torvalds */ 726fee1998eSJonathan Brassow static int init_hash_tables(struct dm_snapshot *s) 7271da177e4SLinus Torvalds { 72860e356f3SMikulas Patocka sector_t hash_size, cow_dev_size, max_buckets; 7291da177e4SLinus Torvalds 7301da177e4SLinus Torvalds /* 7311da177e4SLinus Torvalds * Calculate based on the size of the original volume or 7321da177e4SLinus Torvalds * the COW volume... 7331da177e4SLinus Torvalds */ 734fc56f6fbSMike Snitzer cow_dev_size = get_dev_size(s->cow->bdev); 7351da177e4SLinus Torvalds max_buckets = calc_max_buckets(); 7361da177e4SLinus Torvalds 73760e356f3SMikulas Patocka hash_size = cow_dev_size >> s->store->chunk_shift; 7381da177e4SLinus Torvalds hash_size = min(hash_size, max_buckets); 7391da177e4SLinus Torvalds 7408e87b9b8SMikulas Patocka if (hash_size < 64) 7418e87b9b8SMikulas Patocka hash_size = 64; 7428defd830SRobert P. J. Day hash_size = rounddown_pow_of_two(hash_size); 7433510cb94SJon Brassow if (dm_exception_table_init(&s->complete, hash_size, 744d74f81f8SMilan Broz DM_CHUNK_CONSECUTIVE_BITS)) 7451da177e4SLinus Torvalds return -ENOMEM; 7461da177e4SLinus Torvalds 7471da177e4SLinus Torvalds /* 7481da177e4SLinus Torvalds * Allocate hash table for in-flight exceptions 7491da177e4SLinus Torvalds * Make this smaller than the real hash table 7501da177e4SLinus Torvalds */ 7511da177e4SLinus Torvalds hash_size >>= 3; 7521da177e4SLinus Torvalds if (hash_size < 64) 7531da177e4SLinus Torvalds hash_size = 64; 7541da177e4SLinus Torvalds 7553510cb94SJon Brassow if (dm_exception_table_init(&s->pending, hash_size, 0)) { 7563510cb94SJon Brassow dm_exception_table_exit(&s->complete, exception_cache); 7571da177e4SLinus Torvalds return -ENOMEM; 7581da177e4SLinus Torvalds } 7591da177e4SLinus Torvalds 7601da177e4SLinus Torvalds return 0; 7611da177e4SLinus Torvalds } 7621da177e4SLinus Torvalds 7631e03f97eSMikulas Patocka static void merge_shutdown(struct dm_snapshot *s) 7641e03f97eSMikulas Patocka { 7651e03f97eSMikulas Patocka clear_bit_unlock(RUNNING_MERGE, &s->state_bits); 7661e03f97eSMikulas Patocka smp_mb__after_clear_bit(); 7671e03f97eSMikulas Patocka wake_up_bit(&s->state_bits, RUNNING_MERGE); 7681e03f97eSMikulas Patocka } 7691e03f97eSMikulas Patocka 7709fe86254SMikulas Patocka static struct bio *__release_queued_bios_after_merge(struct dm_snapshot *s) 7719fe86254SMikulas Patocka { 7729fe86254SMikulas Patocka s->first_merging_chunk = 0; 7739fe86254SMikulas Patocka s->num_merging_chunks = 0; 7749fe86254SMikulas Patocka 7759fe86254SMikulas Patocka return bio_list_get(&s->bios_queued_during_merge); 7769fe86254SMikulas Patocka } 7779fe86254SMikulas Patocka 7781e03f97eSMikulas Patocka /* 7791e03f97eSMikulas Patocka * Remove one chunk from the index of completed exceptions. 7801e03f97eSMikulas Patocka */ 7811e03f97eSMikulas Patocka static int __remove_single_exception_chunk(struct dm_snapshot *s, 7821e03f97eSMikulas Patocka chunk_t old_chunk) 7831e03f97eSMikulas Patocka { 7841e03f97eSMikulas Patocka struct dm_exception *e; 7851e03f97eSMikulas Patocka 7861e03f97eSMikulas Patocka e = dm_lookup_exception(&s->complete, old_chunk); 7871e03f97eSMikulas Patocka if (!e) { 7881e03f97eSMikulas Patocka DMERR("Corruption detected: exception for block %llu is " 7891e03f97eSMikulas Patocka "on disk but not in memory", 7901e03f97eSMikulas Patocka (unsigned long long)old_chunk); 7911e03f97eSMikulas Patocka return -EINVAL; 7921e03f97eSMikulas Patocka } 7931e03f97eSMikulas Patocka 7941e03f97eSMikulas Patocka /* 7951e03f97eSMikulas Patocka * If this is the only chunk using this exception, remove exception. 7961e03f97eSMikulas Patocka */ 7971e03f97eSMikulas Patocka if (!dm_consecutive_chunk_count(e)) { 7981e03f97eSMikulas Patocka dm_remove_exception(e); 7991e03f97eSMikulas Patocka free_completed_exception(e); 8001e03f97eSMikulas Patocka return 0; 8011e03f97eSMikulas Patocka } 8021e03f97eSMikulas Patocka 8031e03f97eSMikulas Patocka /* 8041e03f97eSMikulas Patocka * The chunk may be either at the beginning or the end of a 8051e03f97eSMikulas Patocka * group of consecutive chunks - never in the middle. We are 8061e03f97eSMikulas Patocka * removing chunks in the opposite order to that in which they 8071e03f97eSMikulas Patocka * were added, so this should always be true. 8081e03f97eSMikulas Patocka * Decrement the consecutive chunk counter and adjust the 8091e03f97eSMikulas Patocka * starting point if necessary. 8101e03f97eSMikulas Patocka */ 8111e03f97eSMikulas Patocka if (old_chunk == e->old_chunk) { 8121e03f97eSMikulas Patocka e->old_chunk++; 8131e03f97eSMikulas Patocka e->new_chunk++; 8141e03f97eSMikulas Patocka } else if (old_chunk != e->old_chunk + 8151e03f97eSMikulas Patocka dm_consecutive_chunk_count(e)) { 8161e03f97eSMikulas Patocka DMERR("Attempt to merge block %llu from the " 8171e03f97eSMikulas Patocka "middle of a chunk range [%llu - %llu]", 8181e03f97eSMikulas Patocka (unsigned long long)old_chunk, 8191e03f97eSMikulas Patocka (unsigned long long)e->old_chunk, 8201e03f97eSMikulas Patocka (unsigned long long) 8211e03f97eSMikulas Patocka e->old_chunk + dm_consecutive_chunk_count(e)); 8221e03f97eSMikulas Patocka return -EINVAL; 8231e03f97eSMikulas Patocka } 8241e03f97eSMikulas Patocka 8251e03f97eSMikulas Patocka dm_consecutive_chunk_count_dec(e); 8261e03f97eSMikulas Patocka 8271e03f97eSMikulas Patocka return 0; 8281e03f97eSMikulas Patocka } 8291e03f97eSMikulas Patocka 8309fe86254SMikulas Patocka static void flush_bios(struct bio *bio); 8319fe86254SMikulas Patocka 8329fe86254SMikulas Patocka static int remove_single_exception_chunk(struct dm_snapshot *s) 8331e03f97eSMikulas Patocka { 8349fe86254SMikulas Patocka struct bio *b = NULL; 8359fe86254SMikulas Patocka int r; 8369fe86254SMikulas Patocka chunk_t old_chunk = s->first_merging_chunk + s->num_merging_chunks - 1; 8371e03f97eSMikulas Patocka 8381e03f97eSMikulas Patocka down_write(&s->lock); 8399fe86254SMikulas Patocka 8409fe86254SMikulas Patocka /* 8419fe86254SMikulas Patocka * Process chunks (and associated exceptions) in reverse order 8429fe86254SMikulas Patocka * so that dm_consecutive_chunk_count_dec() accounting works. 8439fe86254SMikulas Patocka */ 8449fe86254SMikulas Patocka do { 8451e03f97eSMikulas Patocka r = __remove_single_exception_chunk(s, old_chunk); 8469fe86254SMikulas Patocka if (r) 8479fe86254SMikulas Patocka goto out; 8489fe86254SMikulas Patocka } while (old_chunk-- > s->first_merging_chunk); 8499fe86254SMikulas Patocka 8509fe86254SMikulas Patocka b = __release_queued_bios_after_merge(s); 8519fe86254SMikulas Patocka 8529fe86254SMikulas Patocka out: 8531e03f97eSMikulas Patocka up_write(&s->lock); 8549fe86254SMikulas Patocka if (b) 8559fe86254SMikulas Patocka flush_bios(b); 8561e03f97eSMikulas Patocka 8571e03f97eSMikulas Patocka return r; 8581e03f97eSMikulas Patocka } 8591e03f97eSMikulas Patocka 86073dfd078SMikulas Patocka static int origin_write_extent(struct dm_snapshot *merging_snap, 86173dfd078SMikulas Patocka sector_t sector, unsigned chunk_size); 86273dfd078SMikulas Patocka 8631e03f97eSMikulas Patocka static void merge_callback(int read_err, unsigned long write_err, 8641e03f97eSMikulas Patocka void *context); 8651e03f97eSMikulas Patocka 86673dfd078SMikulas Patocka static uint64_t read_pending_exceptions_done_count(void) 86773dfd078SMikulas Patocka { 86873dfd078SMikulas Patocka uint64_t pending_exceptions_done; 86973dfd078SMikulas Patocka 87073dfd078SMikulas Patocka spin_lock(&_pending_exceptions_done_spinlock); 87173dfd078SMikulas Patocka pending_exceptions_done = _pending_exceptions_done_count; 87273dfd078SMikulas Patocka spin_unlock(&_pending_exceptions_done_spinlock); 87373dfd078SMikulas Patocka 87473dfd078SMikulas Patocka return pending_exceptions_done; 87573dfd078SMikulas Patocka } 87673dfd078SMikulas Patocka 87773dfd078SMikulas Patocka static void increment_pending_exceptions_done_count(void) 87873dfd078SMikulas Patocka { 87973dfd078SMikulas Patocka spin_lock(&_pending_exceptions_done_spinlock); 88073dfd078SMikulas Patocka _pending_exceptions_done_count++; 88173dfd078SMikulas Patocka spin_unlock(&_pending_exceptions_done_spinlock); 88273dfd078SMikulas Patocka 88373dfd078SMikulas Patocka wake_up_all(&_pending_exceptions_done); 88473dfd078SMikulas Patocka } 88573dfd078SMikulas Patocka 8861e03f97eSMikulas Patocka static void snapshot_merge_next_chunks(struct dm_snapshot *s) 8871e03f97eSMikulas Patocka { 8888a2d5286SMike Snitzer int i, linear_chunks; 8891e03f97eSMikulas Patocka chunk_t old_chunk, new_chunk; 8901e03f97eSMikulas Patocka struct dm_io_region src, dest; 8918a2d5286SMike Snitzer sector_t io_size; 89273dfd078SMikulas Patocka uint64_t previous_count; 8931e03f97eSMikulas Patocka 8941e03f97eSMikulas Patocka BUG_ON(!test_bit(RUNNING_MERGE, &s->state_bits)); 8951e03f97eSMikulas Patocka if (unlikely(test_bit(SHUTDOWN_MERGE, &s->state_bits))) 8961e03f97eSMikulas Patocka goto shut; 8971e03f97eSMikulas Patocka 8981e03f97eSMikulas Patocka /* 8991e03f97eSMikulas Patocka * valid flag never changes during merge, so no lock required. 9001e03f97eSMikulas Patocka */ 9011e03f97eSMikulas Patocka if (!s->valid) { 9021e03f97eSMikulas Patocka DMERR("Snapshot is invalid: can't merge"); 9031e03f97eSMikulas Patocka goto shut; 9041e03f97eSMikulas Patocka } 9051e03f97eSMikulas Patocka 9068a2d5286SMike Snitzer linear_chunks = s->store->type->prepare_merge(s->store, &old_chunk, 9078a2d5286SMike Snitzer &new_chunk); 9088a2d5286SMike Snitzer if (linear_chunks <= 0) { 909d8ddb1cfSMike Snitzer if (linear_chunks < 0) { 9101e03f97eSMikulas Patocka DMERR("Read error in exception store: " 9111e03f97eSMikulas Patocka "shutting down merge"); 912d8ddb1cfSMike Snitzer down_write(&s->lock); 913d8ddb1cfSMike Snitzer s->merge_failed = 1; 914d8ddb1cfSMike Snitzer up_write(&s->lock); 915d8ddb1cfSMike Snitzer } 9161e03f97eSMikulas Patocka goto shut; 9171e03f97eSMikulas Patocka } 9181e03f97eSMikulas Patocka 9198a2d5286SMike Snitzer /* Adjust old_chunk and new_chunk to reflect start of linear region */ 9208a2d5286SMike Snitzer old_chunk = old_chunk + 1 - linear_chunks; 9218a2d5286SMike Snitzer new_chunk = new_chunk + 1 - linear_chunks; 9228a2d5286SMike Snitzer 9238a2d5286SMike Snitzer /* 9248a2d5286SMike Snitzer * Use one (potentially large) I/O to copy all 'linear_chunks' 9258a2d5286SMike Snitzer * from the exception store to the origin 9268a2d5286SMike Snitzer */ 9278a2d5286SMike Snitzer io_size = linear_chunks * s->store->chunk_size; 9281e03f97eSMikulas Patocka 9291e03f97eSMikulas Patocka dest.bdev = s->origin->bdev; 9301e03f97eSMikulas Patocka dest.sector = chunk_to_sector(s->store, old_chunk); 9318a2d5286SMike Snitzer dest.count = min(io_size, get_dev_size(dest.bdev) - dest.sector); 9321e03f97eSMikulas Patocka 9331e03f97eSMikulas Patocka src.bdev = s->cow->bdev; 9341e03f97eSMikulas Patocka src.sector = chunk_to_sector(s->store, new_chunk); 9351e03f97eSMikulas Patocka src.count = dest.count; 9361e03f97eSMikulas Patocka 93773dfd078SMikulas Patocka /* 93873dfd078SMikulas Patocka * Reallocate any exceptions needed in other snapshots then 93973dfd078SMikulas Patocka * wait for the pending exceptions to complete. 94073dfd078SMikulas Patocka * Each time any pending exception (globally on the system) 94173dfd078SMikulas Patocka * completes we are woken and repeat the process to find out 94273dfd078SMikulas Patocka * if we can proceed. While this may not seem a particularly 94373dfd078SMikulas Patocka * efficient algorithm, it is not expected to have any 94473dfd078SMikulas Patocka * significant impact on performance. 94573dfd078SMikulas Patocka */ 94673dfd078SMikulas Patocka previous_count = read_pending_exceptions_done_count(); 9478a2d5286SMike Snitzer while (origin_write_extent(s, dest.sector, io_size)) { 94873dfd078SMikulas Patocka wait_event(_pending_exceptions_done, 94973dfd078SMikulas Patocka (read_pending_exceptions_done_count() != 95073dfd078SMikulas Patocka previous_count)); 95173dfd078SMikulas Patocka /* Retry after the wait, until all exceptions are done. */ 95273dfd078SMikulas Patocka previous_count = read_pending_exceptions_done_count(); 95373dfd078SMikulas Patocka } 95473dfd078SMikulas Patocka 9559fe86254SMikulas Patocka down_write(&s->lock); 9569fe86254SMikulas Patocka s->first_merging_chunk = old_chunk; 9578a2d5286SMike Snitzer s->num_merging_chunks = linear_chunks; 9589fe86254SMikulas Patocka up_write(&s->lock); 9599fe86254SMikulas Patocka 9608a2d5286SMike Snitzer /* Wait until writes to all 'linear_chunks' drain */ 9618a2d5286SMike Snitzer for (i = 0; i < linear_chunks; i++) 9628a2d5286SMike Snitzer __check_for_conflicting_io(s, old_chunk + i); 9639fe86254SMikulas Patocka 9641e03f97eSMikulas Patocka dm_kcopyd_copy(s->kcopyd_client, &src, 1, &dest, 0, merge_callback, s); 9651e03f97eSMikulas Patocka return; 9661e03f97eSMikulas Patocka 9671e03f97eSMikulas Patocka shut: 9681e03f97eSMikulas Patocka merge_shutdown(s); 9691e03f97eSMikulas Patocka } 9701e03f97eSMikulas Patocka 9719fe86254SMikulas Patocka static void error_bios(struct bio *bio); 9729fe86254SMikulas Patocka 9731e03f97eSMikulas Patocka static void merge_callback(int read_err, unsigned long write_err, void *context) 9741e03f97eSMikulas Patocka { 9751e03f97eSMikulas Patocka struct dm_snapshot *s = context; 9769fe86254SMikulas Patocka struct bio *b = NULL; 9771e03f97eSMikulas Patocka 9781e03f97eSMikulas Patocka if (read_err || write_err) { 9791e03f97eSMikulas Patocka if (read_err) 9801e03f97eSMikulas Patocka DMERR("Read error: shutting down merge."); 9811e03f97eSMikulas Patocka else 9821e03f97eSMikulas Patocka DMERR("Write error: shutting down merge."); 9831e03f97eSMikulas Patocka goto shut; 9841e03f97eSMikulas Patocka } 9851e03f97eSMikulas Patocka 9869fe86254SMikulas Patocka if (s->store->type->commit_merge(s->store, 9879fe86254SMikulas Patocka s->num_merging_chunks) < 0) { 9881e03f97eSMikulas Patocka DMERR("Write error in exception store: shutting down merge"); 9891e03f97eSMikulas Patocka goto shut; 9901e03f97eSMikulas Patocka } 9911e03f97eSMikulas Patocka 9929fe86254SMikulas Patocka if (remove_single_exception_chunk(s) < 0) 9939fe86254SMikulas Patocka goto shut; 9949fe86254SMikulas Patocka 9951e03f97eSMikulas Patocka snapshot_merge_next_chunks(s); 9961e03f97eSMikulas Patocka 9971e03f97eSMikulas Patocka return; 9981e03f97eSMikulas Patocka 9991e03f97eSMikulas Patocka shut: 10009fe86254SMikulas Patocka down_write(&s->lock); 1001d8ddb1cfSMike Snitzer s->merge_failed = 1; 10029fe86254SMikulas Patocka b = __release_queued_bios_after_merge(s); 10039fe86254SMikulas Patocka up_write(&s->lock); 10049fe86254SMikulas Patocka error_bios(b); 10059fe86254SMikulas Patocka 10061e03f97eSMikulas Patocka merge_shutdown(s); 10071e03f97eSMikulas Patocka } 10081e03f97eSMikulas Patocka 10091e03f97eSMikulas Patocka static void start_merge(struct dm_snapshot *s) 10101e03f97eSMikulas Patocka { 10111e03f97eSMikulas Patocka if (!test_and_set_bit(RUNNING_MERGE, &s->state_bits)) 10121e03f97eSMikulas Patocka snapshot_merge_next_chunks(s); 10131e03f97eSMikulas Patocka } 10141e03f97eSMikulas Patocka 10151e03f97eSMikulas Patocka static int wait_schedule(void *ptr) 10161e03f97eSMikulas Patocka { 10171e03f97eSMikulas Patocka schedule(); 10181e03f97eSMikulas Patocka 10191e03f97eSMikulas Patocka return 0; 10201e03f97eSMikulas Patocka } 10211e03f97eSMikulas Patocka 10221e03f97eSMikulas Patocka /* 10231e03f97eSMikulas Patocka * Stop the merging process and wait until it finishes. 10241e03f97eSMikulas Patocka */ 10251e03f97eSMikulas Patocka static void stop_merge(struct dm_snapshot *s) 10261e03f97eSMikulas Patocka { 10271e03f97eSMikulas Patocka set_bit(SHUTDOWN_MERGE, &s->state_bits); 10281e03f97eSMikulas Patocka wait_on_bit(&s->state_bits, RUNNING_MERGE, wait_schedule, 10291e03f97eSMikulas Patocka TASK_UNINTERRUPTIBLE); 10301e03f97eSMikulas Patocka clear_bit(SHUTDOWN_MERGE, &s->state_bits); 10311e03f97eSMikulas Patocka } 10321e03f97eSMikulas Patocka 10331da177e4SLinus Torvalds /* 10341da177e4SLinus Torvalds * Construct a snapshot mapping: <origin_dev> <COW-dev> <p/n> <chunk-size> 10351da177e4SLinus Torvalds */ 10361da177e4SLinus Torvalds static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv) 10371da177e4SLinus Torvalds { 10381da177e4SLinus Torvalds struct dm_snapshot *s; 1039cd45daffSMikulas Patocka int i; 10401da177e4SLinus Torvalds int r = -EINVAL; 1041fc56f6fbSMike Snitzer char *origin_path, *cow_path; 104255a62eefSAlasdair G Kergon unsigned args_used, num_flush_bios = 1; 104310b8106aSMike Snitzer fmode_t origin_mode = FMODE_READ; 10441da177e4SLinus Torvalds 10454c7e3bf4SMark McLoughlin if (argc != 4) { 104672d94861SAlasdair G Kergon ti->error = "requires exactly 4 arguments"; 10471da177e4SLinus Torvalds r = -EINVAL; 1048fc56f6fbSMike Snitzer goto bad; 10491da177e4SLinus Torvalds } 10501da177e4SLinus Torvalds 105110b8106aSMike Snitzer if (dm_target_is_snapshot_merge(ti)) { 105255a62eefSAlasdair G Kergon num_flush_bios = 2; 105310b8106aSMike Snitzer origin_mode = FMODE_WRITE; 105410b8106aSMike Snitzer } 105510b8106aSMike Snitzer 10561da177e4SLinus Torvalds s = kmalloc(sizeof(*s), GFP_KERNEL); 1057fee1998eSJonathan Brassow if (!s) { 1058a2d2b034SJonathan Brassow ti->error = "Cannot allocate private snapshot structure"; 10591da177e4SLinus Torvalds r = -ENOMEM; 1060fc56f6fbSMike Snitzer goto bad; 10611da177e4SLinus Torvalds } 10621da177e4SLinus Torvalds 1063c2411045SMikulas Patocka origin_path = argv[0]; 1064c2411045SMikulas Patocka argv++; 1065c2411045SMikulas Patocka argc--; 1066c2411045SMikulas Patocka 1067c2411045SMikulas Patocka r = dm_get_device(ti, origin_path, origin_mode, &s->origin); 1068c2411045SMikulas Patocka if (r) { 1069c2411045SMikulas Patocka ti->error = "Cannot get origin device"; 1070c2411045SMikulas Patocka goto bad_origin; 1071c2411045SMikulas Patocka } 1072c2411045SMikulas Patocka 1073fc56f6fbSMike Snitzer cow_path = argv[0]; 1074fc56f6fbSMike Snitzer argv++; 1075fc56f6fbSMike Snitzer argc--; 1076fc56f6fbSMike Snitzer 1077024d37e9SMilan Broz r = dm_get_device(ti, cow_path, dm_table_get_mode(ti->table), &s->cow); 1078fc56f6fbSMike Snitzer if (r) { 1079fc56f6fbSMike Snitzer ti->error = "Cannot get COW device"; 1080fc56f6fbSMike Snitzer goto bad_cow; 1081fc56f6fbSMike Snitzer } 1082fc56f6fbSMike Snitzer 1083fc56f6fbSMike Snitzer r = dm_exception_store_create(ti, argc, argv, s, &args_used, &s->store); 1084fc56f6fbSMike Snitzer if (r) { 1085fc56f6fbSMike Snitzer ti->error = "Couldn't create exception store"; 1086fc56f6fbSMike Snitzer r = -EINVAL; 1087fc56f6fbSMike Snitzer goto bad_store; 1088fc56f6fbSMike Snitzer } 1089fc56f6fbSMike Snitzer 1090fc56f6fbSMike Snitzer argv += args_used; 1091fc56f6fbSMike Snitzer argc -= args_used; 1092fc56f6fbSMike Snitzer 1093fc56f6fbSMike Snitzer s->ti = ti; 10941da177e4SLinus Torvalds s->valid = 1; 1095aa14edebSAlasdair G Kergon s->active = 0; 1096879129d2SMikulas Patocka atomic_set(&s->pending_exceptions_count, 0); 10971da177e4SLinus Torvalds init_rwsem(&s->lock); 1098c1f0c183SMike Snitzer INIT_LIST_HEAD(&s->list); 1099ca3a931fSAlasdair G Kergon spin_lock_init(&s->pe_lock); 11001e03f97eSMikulas Patocka s->state_bits = 0; 1101d8ddb1cfSMike Snitzer s->merge_failed = 0; 11029fe86254SMikulas Patocka s->first_merging_chunk = 0; 11039fe86254SMikulas Patocka s->num_merging_chunks = 0; 11049fe86254SMikulas Patocka bio_list_init(&s->bios_queued_during_merge); 11051da177e4SLinus Torvalds 11061da177e4SLinus Torvalds /* Allocate hash table for COW data */ 1107fee1998eSJonathan Brassow if (init_hash_tables(s)) { 11081da177e4SLinus Torvalds ti->error = "Unable to allocate hash table space"; 11091da177e4SLinus Torvalds r = -ENOMEM; 1110fee1998eSJonathan Brassow goto bad_hash_tables; 11111da177e4SLinus Torvalds } 11121da177e4SLinus Torvalds 1113df5d2e90SMikulas Patocka s->kcopyd_client = dm_kcopyd_client_create(&dm_kcopyd_throttle); 1114fa34ce73SMikulas Patocka if (IS_ERR(s->kcopyd_client)) { 1115fa34ce73SMikulas Patocka r = PTR_ERR(s->kcopyd_client); 11161da177e4SLinus Torvalds ti->error = "Could not create kcopyd client"; 1117fee1998eSJonathan Brassow goto bad_kcopyd; 11181da177e4SLinus Torvalds } 11191da177e4SLinus Torvalds 112092e86812SMikulas Patocka s->pending_pool = mempool_create_slab_pool(MIN_IOS, pending_cache); 112192e86812SMikulas Patocka if (!s->pending_pool) { 112292e86812SMikulas Patocka ti->error = "Could not allocate mempool for pending exceptions"; 112309e8b813SWei Yongjun r = -ENOMEM; 1124fee1998eSJonathan Brassow goto bad_pending_pool; 112592e86812SMikulas Patocka } 112692e86812SMikulas Patocka 1127cd45daffSMikulas Patocka for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) 1128cd45daffSMikulas Patocka INIT_HLIST_HEAD(&s->tracked_chunk_hash[i]); 1129cd45daffSMikulas Patocka 1130cd45daffSMikulas Patocka spin_lock_init(&s->tracked_chunk_lock); 1131cd45daffSMikulas Patocka 1132c1f0c183SMike Snitzer ti->private = s; 113355a62eefSAlasdair G Kergon ti->num_flush_bios = num_flush_bios; 113442bc954fSMikulas Patocka ti->per_bio_data_size = sizeof(struct dm_snap_tracked_chunk); 1135c1f0c183SMike Snitzer 1136c1f0c183SMike Snitzer /* Add snapshot to the list of snapshots for this origin */ 1137c1f0c183SMike Snitzer /* Exceptions aren't triggered till snapshot_resume() is called */ 1138c1f0c183SMike Snitzer r = register_snapshot(s); 1139c1f0c183SMike Snitzer if (r == -ENOMEM) { 1140c1f0c183SMike Snitzer ti->error = "Snapshot origin struct allocation failed"; 1141c1f0c183SMike Snitzer goto bad_load_and_register; 1142c1f0c183SMike Snitzer } else if (r < 0) { 1143c1f0c183SMike Snitzer /* invalid handover, register_snapshot has set ti->error */ 1144c1f0c183SMike Snitzer goto bad_load_and_register; 1145c1f0c183SMike Snitzer } 1146c1f0c183SMike Snitzer 1147c1f0c183SMike Snitzer /* 1148c1f0c183SMike Snitzer * Metadata must only be loaded into one table at once, so skip this 1149c1f0c183SMike Snitzer * if metadata will be handed over during resume. 1150c1f0c183SMike Snitzer * Chunk size will be set during the handover - set it to zero to 1151c1f0c183SMike Snitzer * ensure it's ignored. 1152c1f0c183SMike Snitzer */ 1153c1f0c183SMike Snitzer if (r > 0) { 1154c1f0c183SMike Snitzer s->store->chunk_size = 0; 1155c1f0c183SMike Snitzer return 0; 1156c1f0c183SMike Snitzer } 1157c1f0c183SMike Snitzer 1158493df71cSJonathan Brassow r = s->store->type->read_metadata(s->store, dm_add_exception, 1159493df71cSJonathan Brassow (void *)s); 11600764147bSMilan Broz if (r < 0) { 1161f9cea4f7SMark McLoughlin ti->error = "Failed to read snapshot metadata"; 1162c1f0c183SMike Snitzer goto bad_read_metadata; 11630764147bSMilan Broz } else if (r > 0) { 11640764147bSMilan Broz s->valid = 0; 11650764147bSMilan Broz DMWARN("Snapshot is marked invalid."); 1166f9cea4f7SMark McLoughlin } 1167aa14edebSAlasdair G Kergon 11683f2412dcSMikulas Patocka if (!s->store->chunk_size) { 11693f2412dcSMikulas Patocka ti->error = "Chunk size not set"; 1170c1f0c183SMike Snitzer goto bad_read_metadata; 11713f2412dcSMikulas Patocka } 1172542f9038SMike Snitzer 1173542f9038SMike Snitzer r = dm_set_target_max_io_len(ti, s->store->chunk_size); 1174542f9038SMike Snitzer if (r) 1175542f9038SMike Snitzer goto bad_read_metadata; 11761da177e4SLinus Torvalds 11771da177e4SLinus Torvalds return 0; 11781da177e4SLinus Torvalds 1179c1f0c183SMike Snitzer bad_read_metadata: 1180c1f0c183SMike Snitzer unregister_snapshot(s); 1181c1f0c183SMike Snitzer 1182cd45daffSMikulas Patocka bad_load_and_register: 118392e86812SMikulas Patocka mempool_destroy(s->pending_pool); 118492e86812SMikulas Patocka 1185fee1998eSJonathan Brassow bad_pending_pool: 1186eb69aca5SHeinz Mauelshagen dm_kcopyd_client_destroy(s->kcopyd_client); 11871da177e4SLinus Torvalds 1188fee1998eSJonathan Brassow bad_kcopyd: 11893510cb94SJon Brassow dm_exception_table_exit(&s->pending, pending_cache); 11903510cb94SJon Brassow dm_exception_table_exit(&s->complete, exception_cache); 11911da177e4SLinus Torvalds 1192fee1998eSJonathan Brassow bad_hash_tables: 1193fc56f6fbSMike Snitzer dm_exception_store_destroy(s->store); 1194fc56f6fbSMike Snitzer 1195fc56f6fbSMike Snitzer bad_store: 1196fc56f6fbSMike Snitzer dm_put_device(ti, s->cow); 1197fc56f6fbSMike Snitzer 1198fc56f6fbSMike Snitzer bad_cow: 1199c2411045SMikulas Patocka dm_put_device(ti, s->origin); 1200c2411045SMikulas Patocka 1201c2411045SMikulas Patocka bad_origin: 12021da177e4SLinus Torvalds kfree(s); 12031da177e4SLinus Torvalds 1204fc56f6fbSMike Snitzer bad: 12051da177e4SLinus Torvalds return r; 12061da177e4SLinus Torvalds } 12071da177e4SLinus Torvalds 120831c93a0cSMilan Broz static void __free_exceptions(struct dm_snapshot *s) 120931c93a0cSMilan Broz { 1210eb69aca5SHeinz Mauelshagen dm_kcopyd_client_destroy(s->kcopyd_client); 121131c93a0cSMilan Broz s->kcopyd_client = NULL; 121231c93a0cSMilan Broz 12133510cb94SJon Brassow dm_exception_table_exit(&s->pending, pending_cache); 12143510cb94SJon Brassow dm_exception_table_exit(&s->complete, exception_cache); 121531c93a0cSMilan Broz } 121631c93a0cSMilan Broz 1217c1f0c183SMike Snitzer static void __handover_exceptions(struct dm_snapshot *snap_src, 1218c1f0c183SMike Snitzer struct dm_snapshot *snap_dest) 1219c1f0c183SMike Snitzer { 1220c1f0c183SMike Snitzer union { 1221c1f0c183SMike Snitzer struct dm_exception_table table_swap; 1222c1f0c183SMike Snitzer struct dm_exception_store *store_swap; 1223c1f0c183SMike Snitzer } u; 1224c1f0c183SMike Snitzer 1225c1f0c183SMike Snitzer /* 1226c1f0c183SMike Snitzer * Swap all snapshot context information between the two instances. 1227c1f0c183SMike Snitzer */ 1228c1f0c183SMike Snitzer u.table_swap = snap_dest->complete; 1229c1f0c183SMike Snitzer snap_dest->complete = snap_src->complete; 1230c1f0c183SMike Snitzer snap_src->complete = u.table_swap; 1231c1f0c183SMike Snitzer 1232c1f0c183SMike Snitzer u.store_swap = snap_dest->store; 1233c1f0c183SMike Snitzer snap_dest->store = snap_src->store; 1234c1f0c183SMike Snitzer snap_src->store = u.store_swap; 1235c1f0c183SMike Snitzer 1236c1f0c183SMike Snitzer snap_dest->store->snap = snap_dest; 1237c1f0c183SMike Snitzer snap_src->store->snap = snap_src; 1238c1f0c183SMike Snitzer 1239542f9038SMike Snitzer snap_dest->ti->max_io_len = snap_dest->store->chunk_size; 1240c1f0c183SMike Snitzer snap_dest->valid = snap_src->valid; 1241c1f0c183SMike Snitzer 1242c1f0c183SMike Snitzer /* 1243c1f0c183SMike Snitzer * Set source invalid to ensure it receives no further I/O. 1244c1f0c183SMike Snitzer */ 1245c1f0c183SMike Snitzer snap_src->valid = 0; 1246c1f0c183SMike Snitzer } 1247c1f0c183SMike Snitzer 12481da177e4SLinus Torvalds static void snapshot_dtr(struct dm_target *ti) 12491da177e4SLinus Torvalds { 1250cd45daffSMikulas Patocka #ifdef CONFIG_DM_DEBUG 1251cd45daffSMikulas Patocka int i; 1252cd45daffSMikulas Patocka #endif 1253028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 1254c1f0c183SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 12551da177e4SLinus Torvalds 1256c1f0c183SMike Snitzer down_read(&_origins_lock); 1257c1f0c183SMike Snitzer /* Check whether exception handover must be cancelled */ 12589d3b15c4SMikulas Patocka (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); 1259c1f0c183SMike Snitzer if (snap_src && snap_dest && (s == snap_src)) { 1260c1f0c183SMike Snitzer down_write(&snap_dest->lock); 1261c1f0c183SMike Snitzer snap_dest->valid = 0; 1262c1f0c183SMike Snitzer up_write(&snap_dest->lock); 1263c1f0c183SMike Snitzer DMERR("Cancelling snapshot handover."); 1264c1f0c183SMike Snitzer } 1265c1f0c183SMike Snitzer up_read(&_origins_lock); 1266c1f0c183SMike Snitzer 12671e03f97eSMikulas Patocka if (dm_target_is_snapshot_merge(ti)) 12681e03f97eSMikulas Patocka stop_merge(s); 12691e03f97eSMikulas Patocka 1270138728dcSAlasdair G Kergon /* Prevent further origin writes from using this snapshot. */ 1271138728dcSAlasdair G Kergon /* After this returns there can be no new kcopyd jobs. */ 12721da177e4SLinus Torvalds unregister_snapshot(s); 12731da177e4SLinus Torvalds 1274879129d2SMikulas Patocka while (atomic_read(&s->pending_exceptions_count)) 127590fa1527SMikulas Patocka msleep(1); 1276879129d2SMikulas Patocka /* 1277879129d2SMikulas Patocka * Ensure instructions in mempool_destroy aren't reordered 1278879129d2SMikulas Patocka * before atomic_read. 1279879129d2SMikulas Patocka */ 1280879129d2SMikulas Patocka smp_mb(); 1281879129d2SMikulas Patocka 1282cd45daffSMikulas Patocka #ifdef CONFIG_DM_DEBUG 1283cd45daffSMikulas Patocka for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) 1284cd45daffSMikulas Patocka BUG_ON(!hlist_empty(&s->tracked_chunk_hash[i])); 1285cd45daffSMikulas Patocka #endif 1286cd45daffSMikulas Patocka 128731c93a0cSMilan Broz __free_exceptions(s); 12881da177e4SLinus Torvalds 128992e86812SMikulas Patocka mempool_destroy(s->pending_pool); 129092e86812SMikulas Patocka 1291fee1998eSJonathan Brassow dm_exception_store_destroy(s->store); 1292138728dcSAlasdair G Kergon 1293fc56f6fbSMike Snitzer dm_put_device(ti, s->cow); 1294fc56f6fbSMike Snitzer 1295c2411045SMikulas Patocka dm_put_device(ti, s->origin); 1296c2411045SMikulas Patocka 12971da177e4SLinus Torvalds kfree(s); 12981da177e4SLinus Torvalds } 12991da177e4SLinus Torvalds 13001da177e4SLinus Torvalds /* 13011da177e4SLinus Torvalds * Flush a list of buffers. 13021da177e4SLinus Torvalds */ 13031da177e4SLinus Torvalds static void flush_bios(struct bio *bio) 13041da177e4SLinus Torvalds { 13051da177e4SLinus Torvalds struct bio *n; 13061da177e4SLinus Torvalds 13071da177e4SLinus Torvalds while (bio) { 13081da177e4SLinus Torvalds n = bio->bi_next; 13091da177e4SLinus Torvalds bio->bi_next = NULL; 13101da177e4SLinus Torvalds generic_make_request(bio); 13111da177e4SLinus Torvalds bio = n; 13121da177e4SLinus Torvalds } 13131da177e4SLinus Torvalds } 13141da177e4SLinus Torvalds 1315515ad66cSMikulas Patocka static int do_origin(struct dm_dev *origin, struct bio *bio); 1316515ad66cSMikulas Patocka 1317515ad66cSMikulas Patocka /* 1318515ad66cSMikulas Patocka * Flush a list of buffers. 1319515ad66cSMikulas Patocka */ 1320515ad66cSMikulas Patocka static void retry_origin_bios(struct dm_snapshot *s, struct bio *bio) 1321515ad66cSMikulas Patocka { 1322515ad66cSMikulas Patocka struct bio *n; 1323515ad66cSMikulas Patocka int r; 1324515ad66cSMikulas Patocka 1325515ad66cSMikulas Patocka while (bio) { 1326515ad66cSMikulas Patocka n = bio->bi_next; 1327515ad66cSMikulas Patocka bio->bi_next = NULL; 1328515ad66cSMikulas Patocka r = do_origin(s->origin, bio); 1329515ad66cSMikulas Patocka if (r == DM_MAPIO_REMAPPED) 1330515ad66cSMikulas Patocka generic_make_request(bio); 1331515ad66cSMikulas Patocka bio = n; 1332515ad66cSMikulas Patocka } 1333515ad66cSMikulas Patocka } 1334515ad66cSMikulas Patocka 13351da177e4SLinus Torvalds /* 13361da177e4SLinus Torvalds * Error a list of buffers. 13371da177e4SLinus Torvalds */ 13381da177e4SLinus Torvalds static void error_bios(struct bio *bio) 13391da177e4SLinus Torvalds { 13401da177e4SLinus Torvalds struct bio *n; 13411da177e4SLinus Torvalds 13421da177e4SLinus Torvalds while (bio) { 13431da177e4SLinus Torvalds n = bio->bi_next; 13441da177e4SLinus Torvalds bio->bi_next = NULL; 13456712ecf8SNeilBrown bio_io_error(bio); 13461da177e4SLinus Torvalds bio = n; 13471da177e4SLinus Torvalds } 13481da177e4SLinus Torvalds } 13491da177e4SLinus Torvalds 1350695368acSAlasdair G Kergon static void __invalidate_snapshot(struct dm_snapshot *s, int err) 135176df1c65SAlasdair G Kergon { 135276df1c65SAlasdair G Kergon if (!s->valid) 135376df1c65SAlasdair G Kergon return; 135476df1c65SAlasdair G Kergon 135576df1c65SAlasdair G Kergon if (err == -EIO) 135676df1c65SAlasdair G Kergon DMERR("Invalidating snapshot: Error reading/writing."); 135776df1c65SAlasdair G Kergon else if (err == -ENOMEM) 135876df1c65SAlasdair G Kergon DMERR("Invalidating snapshot: Unable to allocate exception."); 135976df1c65SAlasdair G Kergon 1360493df71cSJonathan Brassow if (s->store->type->drop_snapshot) 1361493df71cSJonathan Brassow s->store->type->drop_snapshot(s->store); 136276df1c65SAlasdair G Kergon 136376df1c65SAlasdair G Kergon s->valid = 0; 136476df1c65SAlasdair G Kergon 1365fc56f6fbSMike Snitzer dm_table_event(s->ti->table); 136676df1c65SAlasdair G Kergon } 136776df1c65SAlasdair G Kergon 1368028867acSAlasdair G Kergon static void pending_complete(struct dm_snap_pending_exception *pe, int success) 13691da177e4SLinus Torvalds { 13701d4989c8SJon Brassow struct dm_exception *e; 13711da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 13729d493fa8SAlasdair G Kergon struct bio *origin_bios = NULL; 13739d493fa8SAlasdair G Kergon struct bio *snapshot_bios = NULL; 1374a6e50b40SMikulas Patocka struct bio *full_bio = NULL; 13759d493fa8SAlasdair G Kergon int error = 0; 13761da177e4SLinus Torvalds 137776df1c65SAlasdair G Kergon if (!success) { 137876df1c65SAlasdair G Kergon /* Read/write error - snapshot is unusable */ 13791da177e4SLinus Torvalds down_write(&s->lock); 1380695368acSAlasdair G Kergon __invalidate_snapshot(s, -EIO); 13819d493fa8SAlasdair G Kergon error = 1; 138276df1c65SAlasdair G Kergon goto out; 138376df1c65SAlasdair G Kergon } 138476df1c65SAlasdair G Kergon 13853510cb94SJon Brassow e = alloc_completed_exception(); 138676df1c65SAlasdair G Kergon if (!e) { 138776df1c65SAlasdair G Kergon down_write(&s->lock); 1388695368acSAlasdair G Kergon __invalidate_snapshot(s, -ENOMEM); 13899d493fa8SAlasdair G Kergon error = 1; 13901da177e4SLinus Torvalds goto out; 13911da177e4SLinus Torvalds } 13921da177e4SLinus Torvalds *e = pe->e; 13931da177e4SLinus Torvalds 13949d493fa8SAlasdair G Kergon down_write(&s->lock); 13959d493fa8SAlasdair G Kergon if (!s->valid) { 13963510cb94SJon Brassow free_completed_exception(e); 13979d493fa8SAlasdair G Kergon error = 1; 13989d493fa8SAlasdair G Kergon goto out; 13999d493fa8SAlasdair G Kergon } 14009d493fa8SAlasdair G Kergon 1401615d1eb9SMike Snitzer /* Check for conflicting reads */ 1402615d1eb9SMike Snitzer __check_for_conflicting_io(s, pe->e.old_chunk); 1403a8d41b59SMikulas Patocka 1404a8d41b59SMikulas Patocka /* 14051da177e4SLinus Torvalds * Add a proper exception, and remove the 14061da177e4SLinus Torvalds * in-flight exception from the list. 14071da177e4SLinus Torvalds */ 14083510cb94SJon Brassow dm_insert_exception(&s->complete, e); 14091da177e4SLinus Torvalds 14101da177e4SLinus Torvalds out: 14113510cb94SJon Brassow dm_remove_exception(&pe->e); 14129d493fa8SAlasdair G Kergon snapshot_bios = bio_list_get(&pe->snapshot_bios); 1413515ad66cSMikulas Patocka origin_bios = bio_list_get(&pe->origin_bios); 1414a6e50b40SMikulas Patocka full_bio = pe->full_bio; 1415a6e50b40SMikulas Patocka if (full_bio) { 1416a6e50b40SMikulas Patocka full_bio->bi_end_io = pe->full_bio_end_io; 1417a6e50b40SMikulas Patocka full_bio->bi_private = pe->full_bio_private; 1418a6e50b40SMikulas Patocka } 1419515ad66cSMikulas Patocka free_pending_exception(pe); 1420b4b610f6SAlasdair G Kergon 142173dfd078SMikulas Patocka increment_pending_exceptions_done_count(); 142273dfd078SMikulas Patocka 14239d493fa8SAlasdair G Kergon up_write(&s->lock); 14249d493fa8SAlasdair G Kergon 14259d493fa8SAlasdair G Kergon /* Submit any pending write bios */ 1426a6e50b40SMikulas Patocka if (error) { 1427a6e50b40SMikulas Patocka if (full_bio) 1428a6e50b40SMikulas Patocka bio_io_error(full_bio); 14299d493fa8SAlasdair G Kergon error_bios(snapshot_bios); 1430a6e50b40SMikulas Patocka } else { 1431a6e50b40SMikulas Patocka if (full_bio) 1432a6e50b40SMikulas Patocka bio_endio(full_bio, 0); 14339d493fa8SAlasdair G Kergon flush_bios(snapshot_bios); 1434a6e50b40SMikulas Patocka } 14359d493fa8SAlasdair G Kergon 1436515ad66cSMikulas Patocka retry_origin_bios(s, origin_bios); 14371da177e4SLinus Torvalds } 14381da177e4SLinus Torvalds 14391da177e4SLinus Torvalds static void commit_callback(void *context, int success) 14401da177e4SLinus Torvalds { 1441028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = context; 1442028867acSAlasdair G Kergon 14431da177e4SLinus Torvalds pending_complete(pe, success); 14441da177e4SLinus Torvalds } 14451da177e4SLinus Torvalds 14461da177e4SLinus Torvalds /* 14471da177e4SLinus Torvalds * Called when the copy I/O has finished. kcopyd actually runs 14481da177e4SLinus Torvalds * this code so don't block. 14491da177e4SLinus Torvalds */ 14504cdc1d1fSAlasdair G Kergon static void copy_callback(int read_err, unsigned long write_err, void *context) 14511da177e4SLinus Torvalds { 1452028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = context; 14531da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 14541da177e4SLinus Torvalds 14551da177e4SLinus Torvalds if (read_err || write_err) 14561da177e4SLinus Torvalds pending_complete(pe, 0); 14571da177e4SLinus Torvalds 14581da177e4SLinus Torvalds else 14591da177e4SLinus Torvalds /* Update the metadata if we are persistent */ 1460493df71cSJonathan Brassow s->store->type->commit_exception(s->store, &pe->e, 1461b2a11465SJonathan Brassow commit_callback, pe); 14621da177e4SLinus Torvalds } 14631da177e4SLinus Torvalds 14641da177e4SLinus Torvalds /* 14651da177e4SLinus Torvalds * Dispatches the copy operation to kcopyd. 14661da177e4SLinus Torvalds */ 1467028867acSAlasdair G Kergon static void start_copy(struct dm_snap_pending_exception *pe) 14681da177e4SLinus Torvalds { 14691da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 147022a1ceb1SHeinz Mauelshagen struct dm_io_region src, dest; 14711da177e4SLinus Torvalds struct block_device *bdev = s->origin->bdev; 14721da177e4SLinus Torvalds sector_t dev_size; 14731da177e4SLinus Torvalds 14741da177e4SLinus Torvalds dev_size = get_dev_size(bdev); 14751da177e4SLinus Torvalds 14761da177e4SLinus Torvalds src.bdev = bdev; 147771fab00aSJonathan Brassow src.sector = chunk_to_sector(s->store, pe->e.old_chunk); 1478df96eee6SMikulas Patocka src.count = min((sector_t)s->store->chunk_size, dev_size - src.sector); 14791da177e4SLinus Torvalds 1480fc56f6fbSMike Snitzer dest.bdev = s->cow->bdev; 148171fab00aSJonathan Brassow dest.sector = chunk_to_sector(s->store, pe->e.new_chunk); 14821da177e4SLinus Torvalds dest.count = src.count; 14831da177e4SLinus Torvalds 14841da177e4SLinus Torvalds /* Hand over to kcopyd */ 1485a2d2b034SJonathan Brassow dm_kcopyd_copy(s->kcopyd_client, &src, 1, &dest, 0, copy_callback, pe); 14861da177e4SLinus Torvalds } 14871da177e4SLinus Torvalds 1488a6e50b40SMikulas Patocka static void full_bio_end_io(struct bio *bio, int error) 1489a6e50b40SMikulas Patocka { 1490a6e50b40SMikulas Patocka void *callback_data = bio->bi_private; 1491a6e50b40SMikulas Patocka 1492a6e50b40SMikulas Patocka dm_kcopyd_do_callback(callback_data, 0, error ? 1 : 0); 1493a6e50b40SMikulas Patocka } 1494a6e50b40SMikulas Patocka 1495a6e50b40SMikulas Patocka static void start_full_bio(struct dm_snap_pending_exception *pe, 1496a6e50b40SMikulas Patocka struct bio *bio) 1497a6e50b40SMikulas Patocka { 1498a6e50b40SMikulas Patocka struct dm_snapshot *s = pe->snap; 1499a6e50b40SMikulas Patocka void *callback_data; 1500a6e50b40SMikulas Patocka 1501a6e50b40SMikulas Patocka pe->full_bio = bio; 1502a6e50b40SMikulas Patocka pe->full_bio_end_io = bio->bi_end_io; 1503a6e50b40SMikulas Patocka pe->full_bio_private = bio->bi_private; 1504a6e50b40SMikulas Patocka 1505a6e50b40SMikulas Patocka callback_data = dm_kcopyd_prepare_callback(s->kcopyd_client, 1506a6e50b40SMikulas Patocka copy_callback, pe); 1507a6e50b40SMikulas Patocka 1508a6e50b40SMikulas Patocka bio->bi_end_io = full_bio_end_io; 1509a6e50b40SMikulas Patocka bio->bi_private = callback_data; 1510a6e50b40SMikulas Patocka 1511a6e50b40SMikulas Patocka generic_make_request(bio); 1512a6e50b40SMikulas Patocka } 1513a6e50b40SMikulas Patocka 15142913808eSMikulas Patocka static struct dm_snap_pending_exception * 15152913808eSMikulas Patocka __lookup_pending_exception(struct dm_snapshot *s, chunk_t chunk) 15162913808eSMikulas Patocka { 15173510cb94SJon Brassow struct dm_exception *e = dm_lookup_exception(&s->pending, chunk); 15182913808eSMikulas Patocka 15192913808eSMikulas Patocka if (!e) 15202913808eSMikulas Patocka return NULL; 15212913808eSMikulas Patocka 15222913808eSMikulas Patocka return container_of(e, struct dm_snap_pending_exception, e); 15232913808eSMikulas Patocka } 15242913808eSMikulas Patocka 15251da177e4SLinus Torvalds /* 15261da177e4SLinus Torvalds * Looks to see if this snapshot already has a pending exception 15271da177e4SLinus Torvalds * for this chunk, otherwise it allocates a new one and inserts 15281da177e4SLinus Torvalds * it into the pending table. 15291da177e4SLinus Torvalds * 15301da177e4SLinus Torvalds * NOTE: a write lock must be held on snap->lock before calling 15311da177e4SLinus Torvalds * this. 15321da177e4SLinus Torvalds */ 1533028867acSAlasdair G Kergon static struct dm_snap_pending_exception * 1534c6621392SMikulas Patocka __find_pending_exception(struct dm_snapshot *s, 1535c6621392SMikulas Patocka struct dm_snap_pending_exception *pe, chunk_t chunk) 15361da177e4SLinus Torvalds { 1537c6621392SMikulas Patocka struct dm_snap_pending_exception *pe2; 153876df1c65SAlasdair G Kergon 15392913808eSMikulas Patocka pe2 = __lookup_pending_exception(s, chunk); 15402913808eSMikulas Patocka if (pe2) { 15411da177e4SLinus Torvalds free_pending_exception(pe); 15422913808eSMikulas Patocka return pe2; 154376df1c65SAlasdair G Kergon } 154476df1c65SAlasdair G Kergon 15451da177e4SLinus Torvalds pe->e.old_chunk = chunk; 15461da177e4SLinus Torvalds bio_list_init(&pe->origin_bios); 15471da177e4SLinus Torvalds bio_list_init(&pe->snapshot_bios); 15481da177e4SLinus Torvalds pe->started = 0; 1549a6e50b40SMikulas Patocka pe->full_bio = NULL; 15501da177e4SLinus Torvalds 1551493df71cSJonathan Brassow if (s->store->type->prepare_exception(s->store, &pe->e)) { 15521da177e4SLinus Torvalds free_pending_exception(pe); 15531da177e4SLinus Torvalds return NULL; 15541da177e4SLinus Torvalds } 15551da177e4SLinus Torvalds 15563510cb94SJon Brassow dm_insert_exception(&s->pending, &pe->e); 15571da177e4SLinus Torvalds 15581da177e4SLinus Torvalds return pe; 15591da177e4SLinus Torvalds } 15601da177e4SLinus Torvalds 15611d4989c8SJon Brassow static void remap_exception(struct dm_snapshot *s, struct dm_exception *e, 1562d74f81f8SMilan Broz struct bio *bio, chunk_t chunk) 15631da177e4SLinus Torvalds { 1564fc56f6fbSMike Snitzer bio->bi_bdev = s->cow->bdev; 15654f024f37SKent Overstreet bio->bi_iter.bi_sector = 15664f024f37SKent Overstreet chunk_to_sector(s->store, dm_chunk_number(e->new_chunk) + 1567d74f81f8SMilan Broz (chunk - e->old_chunk)) + 15684f024f37SKent Overstreet (bio->bi_iter.bi_sector & s->store->chunk_mask); 15691da177e4SLinus Torvalds } 15701da177e4SLinus Torvalds 15717de3ee57SMikulas Patocka static int snapshot_map(struct dm_target *ti, struct bio *bio) 15721da177e4SLinus Torvalds { 15731d4989c8SJon Brassow struct dm_exception *e; 1574028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 1575d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED; 15761da177e4SLinus Torvalds chunk_t chunk; 1577028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = NULL; 15781da177e4SLinus Torvalds 1579ee18026aSMikulas Patocka init_tracked_chunk(bio); 1580ee18026aSMikulas Patocka 1581d87f4c14STejun Heo if (bio->bi_rw & REQ_FLUSH) { 1582fc56f6fbSMike Snitzer bio->bi_bdev = s->cow->bdev; 1583494b3ee7SMikulas Patocka return DM_MAPIO_REMAPPED; 1584494b3ee7SMikulas Patocka } 1585494b3ee7SMikulas Patocka 15864f024f37SKent Overstreet chunk = sector_to_chunk(s->store, bio->bi_iter.bi_sector); 15871da177e4SLinus Torvalds 15881da177e4SLinus Torvalds /* Full snapshots are not usable */ 158976df1c65SAlasdair G Kergon /* To get here the table must be live so s->active is always set. */ 15901da177e4SLinus Torvalds if (!s->valid) 1591f6a80ea8SAlasdair G Kergon return -EIO; 15921da177e4SLinus Torvalds 15931da177e4SLinus Torvalds /* FIXME: should only take write lock if we need 15941da177e4SLinus Torvalds * to copy an exception */ 15951da177e4SLinus Torvalds down_write(&s->lock); 15961da177e4SLinus Torvalds 159776df1c65SAlasdair G Kergon if (!s->valid) { 159876df1c65SAlasdair G Kergon r = -EIO; 159976df1c65SAlasdair G Kergon goto out_unlock; 160076df1c65SAlasdair G Kergon } 160176df1c65SAlasdair G Kergon 16021da177e4SLinus Torvalds /* If the block is already remapped - use that, else remap it */ 16033510cb94SJon Brassow e = dm_lookup_exception(&s->complete, chunk); 16041da177e4SLinus Torvalds if (e) { 1605d74f81f8SMilan Broz remap_exception(s, e, bio, chunk); 160676df1c65SAlasdair G Kergon goto out_unlock; 160776df1c65SAlasdair G Kergon } 16081da177e4SLinus Torvalds 1609ba40a2aaSAlasdair G Kergon /* 1610ba40a2aaSAlasdair G Kergon * Write to snapshot - higher level takes care of RW/RO 1611ba40a2aaSAlasdair G Kergon * flags so we should only get this if we are 1612ba40a2aaSAlasdair G Kergon * writeable. 1613ba40a2aaSAlasdair G Kergon */ 1614ba40a2aaSAlasdair G Kergon if (bio_rw(bio) == WRITE) { 16152913808eSMikulas Patocka pe = __lookup_pending_exception(s, chunk); 16162913808eSMikulas Patocka if (!pe) { 1617c6621392SMikulas Patocka up_write(&s->lock); 1618c6621392SMikulas Patocka pe = alloc_pending_exception(s); 1619c6621392SMikulas Patocka down_write(&s->lock); 1620c6621392SMikulas Patocka 1621c6621392SMikulas Patocka if (!s->valid) { 1622c6621392SMikulas Patocka free_pending_exception(pe); 1623c6621392SMikulas Patocka r = -EIO; 1624c6621392SMikulas Patocka goto out_unlock; 1625c6621392SMikulas Patocka } 1626c6621392SMikulas Patocka 16273510cb94SJon Brassow e = dm_lookup_exception(&s->complete, chunk); 162835bf659bSMikulas Patocka if (e) { 162935bf659bSMikulas Patocka free_pending_exception(pe); 163035bf659bSMikulas Patocka remap_exception(s, e, bio, chunk); 163135bf659bSMikulas Patocka goto out_unlock; 163235bf659bSMikulas Patocka } 163335bf659bSMikulas Patocka 1634c6621392SMikulas Patocka pe = __find_pending_exception(s, pe, chunk); 16351da177e4SLinus Torvalds if (!pe) { 1636695368acSAlasdair G Kergon __invalidate_snapshot(s, -ENOMEM); 16371da177e4SLinus Torvalds r = -EIO; 163876df1c65SAlasdair G Kergon goto out_unlock; 163976df1c65SAlasdair G Kergon } 16402913808eSMikulas Patocka } 164176df1c65SAlasdair G Kergon 1642d74f81f8SMilan Broz remap_exception(s, &pe->e, bio, chunk); 16431da177e4SLinus Torvalds 1644d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 1645ba40a2aaSAlasdair G Kergon 1646a6e50b40SMikulas Patocka if (!pe->started && 16474f024f37SKent Overstreet bio->bi_iter.bi_size == 16484f024f37SKent Overstreet (s->store->chunk_size << SECTOR_SHIFT)) { 1649a6e50b40SMikulas Patocka pe->started = 1; 1650a6e50b40SMikulas Patocka up_write(&s->lock); 1651a6e50b40SMikulas Patocka start_full_bio(pe, bio); 1652a6e50b40SMikulas Patocka goto out; 1653a6e50b40SMikulas Patocka } 1654a6e50b40SMikulas Patocka 1655a6e50b40SMikulas Patocka bio_list_add(&pe->snapshot_bios, bio); 1656a6e50b40SMikulas Patocka 16571da177e4SLinus Torvalds if (!pe->started) { 16581da177e4SLinus Torvalds /* this is protected by snap->lock */ 16591da177e4SLinus Torvalds pe->started = 1; 166076df1c65SAlasdair G Kergon up_write(&s->lock); 166176df1c65SAlasdair G Kergon start_copy(pe); 1662ba40a2aaSAlasdair G Kergon goto out; 1663ba40a2aaSAlasdair G Kergon } 1664cd45daffSMikulas Patocka } else { 16651da177e4SLinus Torvalds bio->bi_bdev = s->origin->bdev; 1666ee18026aSMikulas Patocka track_chunk(s, bio, chunk); 1667cd45daffSMikulas Patocka } 16681da177e4SLinus Torvalds 1669ba40a2aaSAlasdair G Kergon out_unlock: 1670ba40a2aaSAlasdair G Kergon up_write(&s->lock); 1671ba40a2aaSAlasdair G Kergon out: 16721da177e4SLinus Torvalds return r; 16731da177e4SLinus Torvalds } 16741da177e4SLinus Torvalds 16753452c2a1SMikulas Patocka /* 16763452c2a1SMikulas Patocka * A snapshot-merge target behaves like a combination of a snapshot 16773452c2a1SMikulas Patocka * target and a snapshot-origin target. It only generates new 16783452c2a1SMikulas Patocka * exceptions in other snapshots and not in the one that is being 16793452c2a1SMikulas Patocka * merged. 16803452c2a1SMikulas Patocka * 16813452c2a1SMikulas Patocka * For each chunk, if there is an existing exception, it is used to 16823452c2a1SMikulas Patocka * redirect I/O to the cow device. Otherwise I/O is sent to the origin, 16833452c2a1SMikulas Patocka * which in turn might generate exceptions in other snapshots. 16849fe86254SMikulas Patocka * If merging is currently taking place on the chunk in question, the 16859fe86254SMikulas Patocka * I/O is deferred by adding it to s->bios_queued_during_merge. 16863452c2a1SMikulas Patocka */ 16877de3ee57SMikulas Patocka static int snapshot_merge_map(struct dm_target *ti, struct bio *bio) 16883452c2a1SMikulas Patocka { 16893452c2a1SMikulas Patocka struct dm_exception *e; 16903452c2a1SMikulas Patocka struct dm_snapshot *s = ti->private; 16913452c2a1SMikulas Patocka int r = DM_MAPIO_REMAPPED; 16923452c2a1SMikulas Patocka chunk_t chunk; 16933452c2a1SMikulas Patocka 1694ee18026aSMikulas Patocka init_tracked_chunk(bio); 1695ee18026aSMikulas Patocka 1696d87f4c14STejun Heo if (bio->bi_rw & REQ_FLUSH) { 169755a62eefSAlasdair G Kergon if (!dm_bio_get_target_bio_nr(bio)) 169810b8106aSMike Snitzer bio->bi_bdev = s->origin->bdev; 169910b8106aSMike Snitzer else 170010b8106aSMike Snitzer bio->bi_bdev = s->cow->bdev; 170110b8106aSMike Snitzer return DM_MAPIO_REMAPPED; 170210b8106aSMike Snitzer } 170310b8106aSMike Snitzer 17044f024f37SKent Overstreet chunk = sector_to_chunk(s->store, bio->bi_iter.bi_sector); 17053452c2a1SMikulas Patocka 17069fe86254SMikulas Patocka down_write(&s->lock); 17073452c2a1SMikulas Patocka 1708d2fdb776SMikulas Patocka /* Full merging snapshots are redirected to the origin */ 1709d2fdb776SMikulas Patocka if (!s->valid) 1710d2fdb776SMikulas Patocka goto redirect_to_origin; 17113452c2a1SMikulas Patocka 17123452c2a1SMikulas Patocka /* If the block is already remapped - use that */ 17133452c2a1SMikulas Patocka e = dm_lookup_exception(&s->complete, chunk); 17143452c2a1SMikulas Patocka if (e) { 17159fe86254SMikulas Patocka /* Queue writes overlapping with chunks being merged */ 17169fe86254SMikulas Patocka if (bio_rw(bio) == WRITE && 17179fe86254SMikulas Patocka chunk >= s->first_merging_chunk && 17189fe86254SMikulas Patocka chunk < (s->first_merging_chunk + 17199fe86254SMikulas Patocka s->num_merging_chunks)) { 17209fe86254SMikulas Patocka bio->bi_bdev = s->origin->bdev; 17219fe86254SMikulas Patocka bio_list_add(&s->bios_queued_during_merge, bio); 17229fe86254SMikulas Patocka r = DM_MAPIO_SUBMITTED; 17239fe86254SMikulas Patocka goto out_unlock; 17249fe86254SMikulas Patocka } 172517aa0332SMikulas Patocka 17263452c2a1SMikulas Patocka remap_exception(s, e, bio, chunk); 172717aa0332SMikulas Patocka 172817aa0332SMikulas Patocka if (bio_rw(bio) == WRITE) 1729ee18026aSMikulas Patocka track_chunk(s, bio, chunk); 17303452c2a1SMikulas Patocka goto out_unlock; 17313452c2a1SMikulas Patocka } 17323452c2a1SMikulas Patocka 1733d2fdb776SMikulas Patocka redirect_to_origin: 17343452c2a1SMikulas Patocka bio->bi_bdev = s->origin->bdev; 17353452c2a1SMikulas Patocka 17363452c2a1SMikulas Patocka if (bio_rw(bio) == WRITE) { 17379fe86254SMikulas Patocka up_write(&s->lock); 17383452c2a1SMikulas Patocka return do_origin(s->origin, bio); 17393452c2a1SMikulas Patocka } 17403452c2a1SMikulas Patocka 17413452c2a1SMikulas Patocka out_unlock: 17429fe86254SMikulas Patocka up_write(&s->lock); 17433452c2a1SMikulas Patocka 17443452c2a1SMikulas Patocka return r; 17453452c2a1SMikulas Patocka } 17463452c2a1SMikulas Patocka 17477de3ee57SMikulas Patocka static int snapshot_end_io(struct dm_target *ti, struct bio *bio, int error) 1748cd45daffSMikulas Patocka { 1749cd45daffSMikulas Patocka struct dm_snapshot *s = ti->private; 1750cd45daffSMikulas Patocka 1751ee18026aSMikulas Patocka if (is_bio_tracked(bio)) 1752ee18026aSMikulas Patocka stop_tracking_chunk(s, bio); 1753cd45daffSMikulas Patocka 1754cd45daffSMikulas Patocka return 0; 1755cd45daffSMikulas Patocka } 1756cd45daffSMikulas Patocka 17571e03f97eSMikulas Patocka static void snapshot_merge_presuspend(struct dm_target *ti) 17581e03f97eSMikulas Patocka { 17591e03f97eSMikulas Patocka struct dm_snapshot *s = ti->private; 17601e03f97eSMikulas Patocka 17611e03f97eSMikulas Patocka stop_merge(s); 17621e03f97eSMikulas Patocka } 17631e03f97eSMikulas Patocka 1764c1f0c183SMike Snitzer static int snapshot_preresume(struct dm_target *ti) 1765c1f0c183SMike Snitzer { 1766c1f0c183SMike Snitzer int r = 0; 1767c1f0c183SMike Snitzer struct dm_snapshot *s = ti->private; 1768c1f0c183SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 1769c1f0c183SMike Snitzer 1770c1f0c183SMike Snitzer down_read(&_origins_lock); 17719d3b15c4SMikulas Patocka (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); 1772c1f0c183SMike Snitzer if (snap_src && snap_dest) { 1773c1f0c183SMike Snitzer down_read(&snap_src->lock); 1774c1f0c183SMike Snitzer if (s == snap_src) { 1775c1f0c183SMike Snitzer DMERR("Unable to resume snapshot source until " 1776c1f0c183SMike Snitzer "handover completes."); 1777c1f0c183SMike Snitzer r = -EINVAL; 1778b83b2f29SMike Snitzer } else if (!dm_suspended(snap_src->ti)) { 1779c1f0c183SMike Snitzer DMERR("Unable to perform snapshot handover until " 1780c1f0c183SMike Snitzer "source is suspended."); 1781c1f0c183SMike Snitzer r = -EINVAL; 1782c1f0c183SMike Snitzer } 1783c1f0c183SMike Snitzer up_read(&snap_src->lock); 1784c1f0c183SMike Snitzer } 1785c1f0c183SMike Snitzer up_read(&_origins_lock); 1786c1f0c183SMike Snitzer 1787c1f0c183SMike Snitzer return r; 1788c1f0c183SMike Snitzer } 1789c1f0c183SMike Snitzer 17901da177e4SLinus Torvalds static void snapshot_resume(struct dm_target *ti) 17911da177e4SLinus Torvalds { 1792028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 1793c1f0c183SMike Snitzer struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; 1794c1f0c183SMike Snitzer 1795c1f0c183SMike Snitzer down_read(&_origins_lock); 17969d3b15c4SMikulas Patocka (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); 1797c1f0c183SMike Snitzer if (snap_src && snap_dest) { 1798c1f0c183SMike Snitzer down_write(&snap_src->lock); 1799c1f0c183SMike Snitzer down_write_nested(&snap_dest->lock, SINGLE_DEPTH_NESTING); 1800c1f0c183SMike Snitzer __handover_exceptions(snap_src, snap_dest); 1801c1f0c183SMike Snitzer up_write(&snap_dest->lock); 1802c1f0c183SMike Snitzer up_write(&snap_src->lock); 1803c1f0c183SMike Snitzer } 1804c1f0c183SMike Snitzer up_read(&_origins_lock); 1805c1f0c183SMike Snitzer 1806c1f0c183SMike Snitzer /* Now we have correct chunk size, reregister */ 1807c1f0c183SMike Snitzer reregister_snapshot(s); 18081da177e4SLinus Torvalds 1809aa14edebSAlasdair G Kergon down_write(&s->lock); 1810aa14edebSAlasdair G Kergon s->active = 1; 1811aa14edebSAlasdair G Kergon up_write(&s->lock); 18121da177e4SLinus Torvalds } 18131da177e4SLinus Torvalds 1814542f9038SMike Snitzer static uint32_t get_origin_minimum_chunksize(struct block_device *bdev) 18151e03f97eSMikulas Patocka { 1816542f9038SMike Snitzer uint32_t min_chunksize; 18171e03f97eSMikulas Patocka 18181e03f97eSMikulas Patocka down_read(&_origins_lock); 18191e03f97eSMikulas Patocka min_chunksize = __minimum_chunk_size(__lookup_origin(bdev)); 18201e03f97eSMikulas Patocka up_read(&_origins_lock); 18211e03f97eSMikulas Patocka 18221e03f97eSMikulas Patocka return min_chunksize; 18231e03f97eSMikulas Patocka } 18241e03f97eSMikulas Patocka 18251e03f97eSMikulas Patocka static void snapshot_merge_resume(struct dm_target *ti) 18261e03f97eSMikulas Patocka { 18271e03f97eSMikulas Patocka struct dm_snapshot *s = ti->private; 18281e03f97eSMikulas Patocka 18291e03f97eSMikulas Patocka /* 18301e03f97eSMikulas Patocka * Handover exceptions from existing snapshot. 18311e03f97eSMikulas Patocka */ 18321e03f97eSMikulas Patocka snapshot_resume(ti); 18331e03f97eSMikulas Patocka 18341e03f97eSMikulas Patocka /* 1835542f9038SMike Snitzer * snapshot-merge acts as an origin, so set ti->max_io_len 18361e03f97eSMikulas Patocka */ 1837542f9038SMike Snitzer ti->max_io_len = get_origin_minimum_chunksize(s->origin->bdev); 18381e03f97eSMikulas Patocka 18391e03f97eSMikulas Patocka start_merge(s); 18401e03f97eSMikulas Patocka } 18411e03f97eSMikulas Patocka 1842fd7c092eSMikulas Patocka static void snapshot_status(struct dm_target *ti, status_type_t type, 18431f4e0ff0SAlasdair G Kergon unsigned status_flags, char *result, unsigned maxlen) 18441da177e4SLinus Torvalds { 18452e4a31dfSJonathan Brassow unsigned sz = 0; 1846028867acSAlasdair G Kergon struct dm_snapshot *snap = ti->private; 18471da177e4SLinus Torvalds 18481da177e4SLinus Torvalds switch (type) { 18491da177e4SLinus Torvalds case STATUSTYPE_INFO: 185094e76572SMikulas Patocka 185194e76572SMikulas Patocka down_write(&snap->lock); 185294e76572SMikulas Patocka 18531da177e4SLinus Torvalds if (!snap->valid) 18542e4a31dfSJonathan Brassow DMEMIT("Invalid"); 1855d8ddb1cfSMike Snitzer else if (snap->merge_failed) 1856d8ddb1cfSMike Snitzer DMEMIT("Merge failed"); 18571da177e4SLinus Torvalds else { 1858985903bbSMike Snitzer if (snap->store->type->usage) { 1859985903bbSMike Snitzer sector_t total_sectors, sectors_allocated, 1860985903bbSMike Snitzer metadata_sectors; 1861985903bbSMike Snitzer snap->store->type->usage(snap->store, 1862985903bbSMike Snitzer &total_sectors, 1863985903bbSMike Snitzer §ors_allocated, 1864985903bbSMike Snitzer &metadata_sectors); 1865985903bbSMike Snitzer DMEMIT("%llu/%llu %llu", 1866985903bbSMike Snitzer (unsigned long long)sectors_allocated, 1867985903bbSMike Snitzer (unsigned long long)total_sectors, 1868985903bbSMike Snitzer (unsigned long long)metadata_sectors); 18691da177e4SLinus Torvalds } 18701da177e4SLinus Torvalds else 18712e4a31dfSJonathan Brassow DMEMIT("Unknown"); 18721da177e4SLinus Torvalds } 187394e76572SMikulas Patocka 187494e76572SMikulas Patocka up_write(&snap->lock); 187594e76572SMikulas Patocka 18761da177e4SLinus Torvalds break; 18771da177e4SLinus Torvalds 18781da177e4SLinus Torvalds case STATUSTYPE_TABLE: 18791da177e4SLinus Torvalds /* 18801da177e4SLinus Torvalds * kdevname returns a static pointer so we need 18811da177e4SLinus Torvalds * to make private copies if the output is to 18821da177e4SLinus Torvalds * make sense. 18831da177e4SLinus Torvalds */ 1884fc56f6fbSMike Snitzer DMEMIT("%s %s", snap->origin->name, snap->cow->name); 18851e302a92SJonathan Brassow snap->store->type->status(snap->store, type, result + sz, 18861e302a92SJonathan Brassow maxlen - sz); 18871da177e4SLinus Torvalds break; 18881da177e4SLinus Torvalds } 18891da177e4SLinus Torvalds } 18901da177e4SLinus Torvalds 18918811f46cSMike Snitzer static int snapshot_iterate_devices(struct dm_target *ti, 18928811f46cSMike Snitzer iterate_devices_callout_fn fn, void *data) 18938811f46cSMike Snitzer { 18948811f46cSMike Snitzer struct dm_snapshot *snap = ti->private; 18951e5554c8SMikulas Patocka int r; 18968811f46cSMike Snitzer 18971e5554c8SMikulas Patocka r = fn(ti, snap->origin, 0, ti->len, data); 18981e5554c8SMikulas Patocka 18991e5554c8SMikulas Patocka if (!r) 19001e5554c8SMikulas Patocka r = fn(ti, snap->cow, 0, get_dev_size(snap->cow->bdev), data); 19011e5554c8SMikulas Patocka 19021e5554c8SMikulas Patocka return r; 19038811f46cSMike Snitzer } 19048811f46cSMike Snitzer 19058811f46cSMike Snitzer 19061da177e4SLinus Torvalds /*----------------------------------------------------------------- 19071da177e4SLinus Torvalds * Origin methods 19081da177e4SLinus Torvalds *---------------------------------------------------------------*/ 19099eaae8ffSMikulas Patocka 19109eaae8ffSMikulas Patocka /* 19119eaae8ffSMikulas Patocka * If no exceptions need creating, DM_MAPIO_REMAPPED is returned and any 19129eaae8ffSMikulas Patocka * supplied bio was ignored. The caller may submit it immediately. 19139eaae8ffSMikulas Patocka * (No remapping actually occurs as the origin is always a direct linear 19149eaae8ffSMikulas Patocka * map.) 19159eaae8ffSMikulas Patocka * 19169eaae8ffSMikulas Patocka * If further exceptions are required, DM_MAPIO_SUBMITTED is returned 19179eaae8ffSMikulas Patocka * and any supplied bio is added to a list to be submitted once all 19189eaae8ffSMikulas Patocka * the necessary exceptions exist. 19199eaae8ffSMikulas Patocka */ 19209eaae8ffSMikulas Patocka static int __origin_write(struct list_head *snapshots, sector_t sector, 19219eaae8ffSMikulas Patocka struct bio *bio) 19221da177e4SLinus Torvalds { 1923515ad66cSMikulas Patocka int r = DM_MAPIO_REMAPPED; 19241da177e4SLinus Torvalds struct dm_snapshot *snap; 19251d4989c8SJon Brassow struct dm_exception *e; 1926515ad66cSMikulas Patocka struct dm_snap_pending_exception *pe; 1927515ad66cSMikulas Patocka struct dm_snap_pending_exception *pe_to_start_now = NULL; 1928515ad66cSMikulas Patocka struct dm_snap_pending_exception *pe_to_start_last = NULL; 19291da177e4SLinus Torvalds chunk_t chunk; 19301da177e4SLinus Torvalds 19311da177e4SLinus Torvalds /* Do all the snapshots on this origin */ 19321da177e4SLinus Torvalds list_for_each_entry (snap, snapshots, list) { 19333452c2a1SMikulas Patocka /* 19343452c2a1SMikulas Patocka * Don't make new exceptions in a merging snapshot 19353452c2a1SMikulas Patocka * because it has effectively been deleted 19363452c2a1SMikulas Patocka */ 19373452c2a1SMikulas Patocka if (dm_target_is_snapshot_merge(snap->ti)) 19383452c2a1SMikulas Patocka continue; 19393452c2a1SMikulas Patocka 194076df1c65SAlasdair G Kergon down_write(&snap->lock); 194176df1c65SAlasdair G Kergon 1942aa14edebSAlasdair G Kergon /* Only deal with valid and active snapshots */ 1943aa14edebSAlasdair G Kergon if (!snap->valid || !snap->active) 194476df1c65SAlasdair G Kergon goto next_snapshot; 19451da177e4SLinus Torvalds 1946d5e404c1SAlasdair G Kergon /* Nothing to do if writing beyond end of snapshot */ 19479eaae8ffSMikulas Patocka if (sector >= dm_table_get_size(snap->ti->table)) 194876df1c65SAlasdair G Kergon goto next_snapshot; 19491da177e4SLinus Torvalds 19501da177e4SLinus Torvalds /* 19511da177e4SLinus Torvalds * Remember, different snapshots can have 19521da177e4SLinus Torvalds * different chunk sizes. 19531da177e4SLinus Torvalds */ 19549eaae8ffSMikulas Patocka chunk = sector_to_chunk(snap->store, sector); 19551da177e4SLinus Torvalds 19561da177e4SLinus Torvalds /* 19571da177e4SLinus Torvalds * Check exception table to see if block 19581da177e4SLinus Torvalds * is already remapped in this snapshot 19591da177e4SLinus Torvalds * and trigger an exception if not. 19601da177e4SLinus Torvalds */ 19613510cb94SJon Brassow e = dm_lookup_exception(&snap->complete, chunk); 196276df1c65SAlasdair G Kergon if (e) 196376df1c65SAlasdair G Kergon goto next_snapshot; 196476df1c65SAlasdair G Kergon 19652913808eSMikulas Patocka pe = __lookup_pending_exception(snap, chunk); 19662913808eSMikulas Patocka if (!pe) { 1967c6621392SMikulas Patocka up_write(&snap->lock); 1968c6621392SMikulas Patocka pe = alloc_pending_exception(snap); 1969c6621392SMikulas Patocka down_write(&snap->lock); 1970c6621392SMikulas Patocka 1971c6621392SMikulas Patocka if (!snap->valid) { 1972c6621392SMikulas Patocka free_pending_exception(pe); 1973c6621392SMikulas Patocka goto next_snapshot; 1974c6621392SMikulas Patocka } 1975c6621392SMikulas Patocka 19763510cb94SJon Brassow e = dm_lookup_exception(&snap->complete, chunk); 197735bf659bSMikulas Patocka if (e) { 197835bf659bSMikulas Patocka free_pending_exception(pe); 197935bf659bSMikulas Patocka goto next_snapshot; 198035bf659bSMikulas Patocka } 198135bf659bSMikulas Patocka 1982c6621392SMikulas Patocka pe = __find_pending_exception(snap, pe, chunk); 19831da177e4SLinus Torvalds if (!pe) { 1984695368acSAlasdair G Kergon __invalidate_snapshot(snap, -ENOMEM); 198576df1c65SAlasdair G Kergon goto next_snapshot; 198676df1c65SAlasdair G Kergon } 19872913808eSMikulas Patocka } 19881da177e4SLinus Torvalds 1989d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 199076df1c65SAlasdair G Kergon 1991515ad66cSMikulas Patocka /* 1992515ad66cSMikulas Patocka * If an origin bio was supplied, queue it to wait for the 1993515ad66cSMikulas Patocka * completion of this exception, and start this one last, 1994515ad66cSMikulas Patocka * at the end of the function. 1995515ad66cSMikulas Patocka */ 1996515ad66cSMikulas Patocka if (bio) { 1997515ad66cSMikulas Patocka bio_list_add(&pe->origin_bios, bio); 1998515ad66cSMikulas Patocka bio = NULL; 1999515ad66cSMikulas Patocka 2000515ad66cSMikulas Patocka if (!pe->started) { 2001515ad66cSMikulas Patocka pe->started = 1; 2002515ad66cSMikulas Patocka pe_to_start_last = pe; 2003515ad66cSMikulas Patocka } 2004b4b610f6SAlasdair G Kergon } 200576df1c65SAlasdair G Kergon 2006eccf0817SAlasdair G Kergon if (!pe->started) { 2007eccf0817SAlasdair G Kergon pe->started = 1; 2008515ad66cSMikulas Patocka pe_to_start_now = pe; 2009eccf0817SAlasdair G Kergon } 20101da177e4SLinus Torvalds 201176df1c65SAlasdair G Kergon next_snapshot: 20121da177e4SLinus Torvalds up_write(&snap->lock); 2013515ad66cSMikulas Patocka 2014515ad66cSMikulas Patocka if (pe_to_start_now) { 2015515ad66cSMikulas Patocka start_copy(pe_to_start_now); 2016515ad66cSMikulas Patocka pe_to_start_now = NULL; 20171da177e4SLinus Torvalds } 2018b4b610f6SAlasdair G Kergon } 2019b4b610f6SAlasdair G Kergon 20201da177e4SLinus Torvalds /* 2021515ad66cSMikulas Patocka * Submit the exception against which the bio is queued last, 2022515ad66cSMikulas Patocka * to give the other exceptions a head start. 20231da177e4SLinus Torvalds */ 2024515ad66cSMikulas Patocka if (pe_to_start_last) 2025515ad66cSMikulas Patocka start_copy(pe_to_start_last); 20261da177e4SLinus Torvalds 20271da177e4SLinus Torvalds return r; 20281da177e4SLinus Torvalds } 20291da177e4SLinus Torvalds 20301da177e4SLinus Torvalds /* 20311da177e4SLinus Torvalds * Called on a write from the origin driver. 20321da177e4SLinus Torvalds */ 20331da177e4SLinus Torvalds static int do_origin(struct dm_dev *origin, struct bio *bio) 20341da177e4SLinus Torvalds { 20351da177e4SLinus Torvalds struct origin *o; 2036d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED; 20371da177e4SLinus Torvalds 20381da177e4SLinus Torvalds down_read(&_origins_lock); 20391da177e4SLinus Torvalds o = __lookup_origin(origin->bdev); 20401da177e4SLinus Torvalds if (o) 20414f024f37SKent Overstreet r = __origin_write(&o->snapshots, bio->bi_iter.bi_sector, bio); 20421da177e4SLinus Torvalds up_read(&_origins_lock); 20431da177e4SLinus Torvalds 20441da177e4SLinus Torvalds return r; 20451da177e4SLinus Torvalds } 20461da177e4SLinus Torvalds 20471da177e4SLinus Torvalds /* 204873dfd078SMikulas Patocka * Trigger exceptions in all non-merging snapshots. 204973dfd078SMikulas Patocka * 205073dfd078SMikulas Patocka * The chunk size of the merging snapshot may be larger than the chunk 205173dfd078SMikulas Patocka * size of some other snapshot so we may need to reallocate multiple 205273dfd078SMikulas Patocka * chunks in other snapshots. 205373dfd078SMikulas Patocka * 205473dfd078SMikulas Patocka * We scan all the overlapping exceptions in the other snapshots. 205573dfd078SMikulas Patocka * Returns 1 if anything was reallocated and must be waited for, 205673dfd078SMikulas Patocka * otherwise returns 0. 205773dfd078SMikulas Patocka * 205873dfd078SMikulas Patocka * size must be a multiple of merging_snap's chunk_size. 205973dfd078SMikulas Patocka */ 206073dfd078SMikulas Patocka static int origin_write_extent(struct dm_snapshot *merging_snap, 206173dfd078SMikulas Patocka sector_t sector, unsigned size) 206273dfd078SMikulas Patocka { 206373dfd078SMikulas Patocka int must_wait = 0; 206473dfd078SMikulas Patocka sector_t n; 206573dfd078SMikulas Patocka struct origin *o; 206673dfd078SMikulas Patocka 206773dfd078SMikulas Patocka /* 2068542f9038SMike Snitzer * The origin's __minimum_chunk_size() got stored in max_io_len 206973dfd078SMikulas Patocka * by snapshot_merge_resume(). 207073dfd078SMikulas Patocka */ 207173dfd078SMikulas Patocka down_read(&_origins_lock); 207273dfd078SMikulas Patocka o = __lookup_origin(merging_snap->origin->bdev); 2073542f9038SMike Snitzer for (n = 0; n < size; n += merging_snap->ti->max_io_len) 207473dfd078SMikulas Patocka if (__origin_write(&o->snapshots, sector + n, NULL) == 207573dfd078SMikulas Patocka DM_MAPIO_SUBMITTED) 207673dfd078SMikulas Patocka must_wait = 1; 207773dfd078SMikulas Patocka up_read(&_origins_lock); 207873dfd078SMikulas Patocka 207973dfd078SMikulas Patocka return must_wait; 208073dfd078SMikulas Patocka } 208173dfd078SMikulas Patocka 208273dfd078SMikulas Patocka /* 20831da177e4SLinus Torvalds * Origin: maps a linear range of a device, with hooks for snapshotting. 20841da177e4SLinus Torvalds */ 20851da177e4SLinus Torvalds 20861da177e4SLinus Torvalds /* 20871da177e4SLinus Torvalds * Construct an origin mapping: <dev_path> 20881da177e4SLinus Torvalds * The context for an origin is merely a 'struct dm_dev *' 20891da177e4SLinus Torvalds * pointing to the real device. 20901da177e4SLinus Torvalds */ 20911da177e4SLinus Torvalds static int origin_ctr(struct dm_target *ti, unsigned int argc, char **argv) 20921da177e4SLinus Torvalds { 20931da177e4SLinus Torvalds int r; 20941da177e4SLinus Torvalds struct dm_dev *dev; 20951da177e4SLinus Torvalds 20961da177e4SLinus Torvalds if (argc != 1) { 209772d94861SAlasdair G Kergon ti->error = "origin: incorrect number of arguments"; 20981da177e4SLinus Torvalds return -EINVAL; 20991da177e4SLinus Torvalds } 21001da177e4SLinus Torvalds 21018215d6ecSNikanth Karthikesan r = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &dev); 21021da177e4SLinus Torvalds if (r) { 21031da177e4SLinus Torvalds ti->error = "Cannot get target device"; 21041da177e4SLinus Torvalds return r; 21051da177e4SLinus Torvalds } 21061da177e4SLinus Torvalds 21071da177e4SLinus Torvalds ti->private = dev; 210855a62eefSAlasdair G Kergon ti->num_flush_bios = 1; 2109494b3ee7SMikulas Patocka 21101da177e4SLinus Torvalds return 0; 21111da177e4SLinus Torvalds } 21121da177e4SLinus Torvalds 21131da177e4SLinus Torvalds static void origin_dtr(struct dm_target *ti) 21141da177e4SLinus Torvalds { 2115028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 21161da177e4SLinus Torvalds dm_put_device(ti, dev); 21171da177e4SLinus Torvalds } 21181da177e4SLinus Torvalds 21197de3ee57SMikulas Patocka static int origin_map(struct dm_target *ti, struct bio *bio) 21201da177e4SLinus Torvalds { 2121028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 21221da177e4SLinus Torvalds bio->bi_bdev = dev->bdev; 21231da177e4SLinus Torvalds 2124d87f4c14STejun Heo if (bio->bi_rw & REQ_FLUSH) 2125494b3ee7SMikulas Patocka return DM_MAPIO_REMAPPED; 2126494b3ee7SMikulas Patocka 21271da177e4SLinus Torvalds /* Only tell snapshots if this is a write */ 2128d2a7ad29SKiyoshi Ueda return (bio_rw(bio) == WRITE) ? do_origin(dev, bio) : DM_MAPIO_REMAPPED; 21291da177e4SLinus Torvalds } 21301da177e4SLinus Torvalds 21311da177e4SLinus Torvalds /* 2132542f9038SMike Snitzer * Set the target "max_io_len" field to the minimum of all the snapshots' 21331da177e4SLinus Torvalds * chunk sizes. 21341da177e4SLinus Torvalds */ 21351da177e4SLinus Torvalds static void origin_resume(struct dm_target *ti) 21361da177e4SLinus Torvalds { 2137028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 21381da177e4SLinus Torvalds 2139542f9038SMike Snitzer ti->max_io_len = get_origin_minimum_chunksize(dev->bdev); 21401da177e4SLinus Torvalds } 21411da177e4SLinus Torvalds 2142fd7c092eSMikulas Patocka static void origin_status(struct dm_target *ti, status_type_t type, 21431f4e0ff0SAlasdair G Kergon unsigned status_flags, char *result, unsigned maxlen) 21441da177e4SLinus Torvalds { 2145028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 21461da177e4SLinus Torvalds 21471da177e4SLinus Torvalds switch (type) { 21481da177e4SLinus Torvalds case STATUSTYPE_INFO: 21491da177e4SLinus Torvalds result[0] = '\0'; 21501da177e4SLinus Torvalds break; 21511da177e4SLinus Torvalds 21521da177e4SLinus Torvalds case STATUSTYPE_TABLE: 21531da177e4SLinus Torvalds snprintf(result, maxlen, "%s", dev->name); 21541da177e4SLinus Torvalds break; 21551da177e4SLinus Torvalds } 21561da177e4SLinus Torvalds } 21571da177e4SLinus Torvalds 2158b1d55528SMikulas Patocka static int origin_merge(struct dm_target *ti, struct bvec_merge_data *bvm, 2159b1d55528SMikulas Patocka struct bio_vec *biovec, int max_size) 2160b1d55528SMikulas Patocka { 2161b1d55528SMikulas Patocka struct dm_dev *dev = ti->private; 2162b1d55528SMikulas Patocka struct request_queue *q = bdev_get_queue(dev->bdev); 2163b1d55528SMikulas Patocka 2164b1d55528SMikulas Patocka if (!q->merge_bvec_fn) 2165b1d55528SMikulas Patocka return max_size; 2166b1d55528SMikulas Patocka 2167b1d55528SMikulas Patocka bvm->bi_bdev = dev->bdev; 2168b1d55528SMikulas Patocka 2169b1d55528SMikulas Patocka return min(max_size, q->merge_bvec_fn(q, bvm, biovec)); 2170b1d55528SMikulas Patocka } 2171b1d55528SMikulas Patocka 21728811f46cSMike Snitzer static int origin_iterate_devices(struct dm_target *ti, 21738811f46cSMike Snitzer iterate_devices_callout_fn fn, void *data) 21748811f46cSMike Snitzer { 21758811f46cSMike Snitzer struct dm_dev *dev = ti->private; 21768811f46cSMike Snitzer 21778811f46cSMike Snitzer return fn(ti, dev, 0, ti->len, data); 21788811f46cSMike Snitzer } 21798811f46cSMike Snitzer 21801da177e4SLinus Torvalds static struct target_type origin_target = { 21811da177e4SLinus Torvalds .name = "snapshot-origin", 2182fd7c092eSMikulas Patocka .version = {1, 8, 1}, 21831da177e4SLinus Torvalds .module = THIS_MODULE, 21841da177e4SLinus Torvalds .ctr = origin_ctr, 21851da177e4SLinus Torvalds .dtr = origin_dtr, 21861da177e4SLinus Torvalds .map = origin_map, 21871da177e4SLinus Torvalds .resume = origin_resume, 21881da177e4SLinus Torvalds .status = origin_status, 2189b1d55528SMikulas Patocka .merge = origin_merge, 21908811f46cSMike Snitzer .iterate_devices = origin_iterate_devices, 21911da177e4SLinus Torvalds }; 21921da177e4SLinus Torvalds 21931da177e4SLinus Torvalds static struct target_type snapshot_target = { 21941da177e4SLinus Torvalds .name = "snapshot", 2195fd7c092eSMikulas Patocka .version = {1, 11, 1}, 21961da177e4SLinus Torvalds .module = THIS_MODULE, 21971da177e4SLinus Torvalds .ctr = snapshot_ctr, 21981da177e4SLinus Torvalds .dtr = snapshot_dtr, 21991da177e4SLinus Torvalds .map = snapshot_map, 2200cd45daffSMikulas Patocka .end_io = snapshot_end_io, 2201c1f0c183SMike Snitzer .preresume = snapshot_preresume, 22021da177e4SLinus Torvalds .resume = snapshot_resume, 22031da177e4SLinus Torvalds .status = snapshot_status, 22048811f46cSMike Snitzer .iterate_devices = snapshot_iterate_devices, 22051da177e4SLinus Torvalds }; 22061da177e4SLinus Torvalds 2207d698aa45SMikulas Patocka static struct target_type merge_target = { 2208d698aa45SMikulas Patocka .name = dm_snapshot_merge_target_name, 220942bc954fSMikulas Patocka .version = {1, 2, 0}, 2210d698aa45SMikulas Patocka .module = THIS_MODULE, 2211d698aa45SMikulas Patocka .ctr = snapshot_ctr, 2212d698aa45SMikulas Patocka .dtr = snapshot_dtr, 22133452c2a1SMikulas Patocka .map = snapshot_merge_map, 2214d698aa45SMikulas Patocka .end_io = snapshot_end_io, 22151e03f97eSMikulas Patocka .presuspend = snapshot_merge_presuspend, 2216d698aa45SMikulas Patocka .preresume = snapshot_preresume, 22171e03f97eSMikulas Patocka .resume = snapshot_merge_resume, 2218d698aa45SMikulas Patocka .status = snapshot_status, 2219d698aa45SMikulas Patocka .iterate_devices = snapshot_iterate_devices, 2220d698aa45SMikulas Patocka }; 2221d698aa45SMikulas Patocka 22221da177e4SLinus Torvalds static int __init dm_snapshot_init(void) 22231da177e4SLinus Torvalds { 22241da177e4SLinus Torvalds int r; 22251da177e4SLinus Torvalds 22264db6bfe0SAlasdair G Kergon r = dm_exception_store_init(); 22274db6bfe0SAlasdair G Kergon if (r) { 22284db6bfe0SAlasdair G Kergon DMERR("Failed to initialize exception stores"); 22294db6bfe0SAlasdair G Kergon return r; 22304db6bfe0SAlasdair G Kergon } 22314db6bfe0SAlasdair G Kergon 22321da177e4SLinus Torvalds r = dm_register_target(&snapshot_target); 2233d698aa45SMikulas Patocka if (r < 0) { 22341da177e4SLinus Torvalds DMERR("snapshot target register failed %d", r); 2235034a186dSJonathan Brassow goto bad_register_snapshot_target; 22361da177e4SLinus Torvalds } 22371da177e4SLinus Torvalds 22381da177e4SLinus Torvalds r = dm_register_target(&origin_target); 22391da177e4SLinus Torvalds if (r < 0) { 224072d94861SAlasdair G Kergon DMERR("Origin target register failed %d", r); 2241d698aa45SMikulas Patocka goto bad_register_origin_target; 2242d698aa45SMikulas Patocka } 2243d698aa45SMikulas Patocka 2244d698aa45SMikulas Patocka r = dm_register_target(&merge_target); 2245d698aa45SMikulas Patocka if (r < 0) { 2246d698aa45SMikulas Patocka DMERR("Merge target register failed %d", r); 2247d698aa45SMikulas Patocka goto bad_register_merge_target; 22481da177e4SLinus Torvalds } 22491da177e4SLinus Torvalds 22501da177e4SLinus Torvalds r = init_origin_hash(); 22511da177e4SLinus Torvalds if (r) { 22521da177e4SLinus Torvalds DMERR("init_origin_hash failed."); 2253d698aa45SMikulas Patocka goto bad_origin_hash; 22541da177e4SLinus Torvalds } 22551da177e4SLinus Torvalds 22561d4989c8SJon Brassow exception_cache = KMEM_CACHE(dm_exception, 0); 22571da177e4SLinus Torvalds if (!exception_cache) { 22581da177e4SLinus Torvalds DMERR("Couldn't create exception cache."); 22591da177e4SLinus Torvalds r = -ENOMEM; 2260d698aa45SMikulas Patocka goto bad_exception_cache; 22611da177e4SLinus Torvalds } 22621da177e4SLinus Torvalds 2263028867acSAlasdair G Kergon pending_cache = KMEM_CACHE(dm_snap_pending_exception, 0); 22641da177e4SLinus Torvalds if (!pending_cache) { 22651da177e4SLinus Torvalds DMERR("Couldn't create pending cache."); 22661da177e4SLinus Torvalds r = -ENOMEM; 2267d698aa45SMikulas Patocka goto bad_pending_cache; 22681da177e4SLinus Torvalds } 22691da177e4SLinus Torvalds 22701da177e4SLinus Torvalds return 0; 22711da177e4SLinus Torvalds 2272d698aa45SMikulas Patocka bad_pending_cache: 22731da177e4SLinus Torvalds kmem_cache_destroy(exception_cache); 2274d698aa45SMikulas Patocka bad_exception_cache: 22751da177e4SLinus Torvalds exit_origin_hash(); 2276d698aa45SMikulas Patocka bad_origin_hash: 2277d698aa45SMikulas Patocka dm_unregister_target(&merge_target); 2278d698aa45SMikulas Patocka bad_register_merge_target: 22791da177e4SLinus Torvalds dm_unregister_target(&origin_target); 2280d698aa45SMikulas Patocka bad_register_origin_target: 22811da177e4SLinus Torvalds dm_unregister_target(&snapshot_target); 2282034a186dSJonathan Brassow bad_register_snapshot_target: 2283034a186dSJonathan Brassow dm_exception_store_exit(); 2284d698aa45SMikulas Patocka 22851da177e4SLinus Torvalds return r; 22861da177e4SLinus Torvalds } 22871da177e4SLinus Torvalds 22881da177e4SLinus Torvalds static void __exit dm_snapshot_exit(void) 22891da177e4SLinus Torvalds { 229010d3bd09SMikulas Patocka dm_unregister_target(&snapshot_target); 229110d3bd09SMikulas Patocka dm_unregister_target(&origin_target); 2292d698aa45SMikulas Patocka dm_unregister_target(&merge_target); 22931da177e4SLinus Torvalds 22941da177e4SLinus Torvalds exit_origin_hash(); 22951da177e4SLinus Torvalds kmem_cache_destroy(pending_cache); 22961da177e4SLinus Torvalds kmem_cache_destroy(exception_cache); 22974db6bfe0SAlasdair G Kergon 22984db6bfe0SAlasdair G Kergon dm_exception_store_exit(); 22991da177e4SLinus Torvalds } 23001da177e4SLinus Torvalds 23011da177e4SLinus Torvalds /* Module hooks */ 23021da177e4SLinus Torvalds module_init(dm_snapshot_init); 23031da177e4SLinus Torvalds module_exit(dm_snapshot_exit); 23041da177e4SLinus Torvalds 23051da177e4SLinus Torvalds MODULE_DESCRIPTION(DM_NAME " snapshot target"); 23061da177e4SLinus Torvalds MODULE_AUTHOR("Joe Thornber"); 23071da177e4SLinus Torvalds MODULE_LICENSE("GPL"); 230823cb2109SMikulas Patocka MODULE_ALIAS("dm-snapshot-origin"); 230923cb2109SMikulas Patocka MODULE_ALIAS("dm-snapshot-merge"); 2310