11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * dm-snapshot.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 2001-2002 Sistina Software (UK) Limited. 51da177e4SLinus Torvalds * 61da177e4SLinus Torvalds * This file is released under the GPL. 71da177e4SLinus Torvalds */ 81da177e4SLinus Torvalds 91da177e4SLinus Torvalds #include <linux/blkdev.h> 101da177e4SLinus Torvalds #include <linux/device-mapper.h> 1190fa1527SMikulas Patocka #include <linux/delay.h> 121da177e4SLinus Torvalds #include <linux/fs.h> 131da177e4SLinus Torvalds #include <linux/init.h> 141da177e4SLinus Torvalds #include <linux/kdev_t.h> 151da177e4SLinus Torvalds #include <linux/list.h> 161da177e4SLinus Torvalds #include <linux/mempool.h> 171da177e4SLinus Torvalds #include <linux/module.h> 181da177e4SLinus Torvalds #include <linux/slab.h> 191da177e4SLinus Torvalds #include <linux/vmalloc.h> 206f3c3f0aSvignesh babu #include <linux/log2.h> 21a765e20eSAlasdair G Kergon #include <linux/dm-kcopyd.h> 22ccc45ea8SJonathan Brassow #include <linux/workqueue.h> 231da177e4SLinus Torvalds 24aea53d92SJonathan Brassow #include "dm-exception-store.h" 251da177e4SLinus Torvalds 2672d94861SAlasdair G Kergon #define DM_MSG_PREFIX "snapshots" 2772d94861SAlasdair G Kergon 281da177e4SLinus Torvalds /* 291da177e4SLinus Torvalds * The percentage increment we will wake up users at 301da177e4SLinus Torvalds */ 311da177e4SLinus Torvalds #define WAKE_UP_PERCENT 5 321da177e4SLinus Torvalds 331da177e4SLinus Torvalds /* 341da177e4SLinus Torvalds * kcopyd priority of snapshot operations 351da177e4SLinus Torvalds */ 361da177e4SLinus Torvalds #define SNAPSHOT_COPY_PRIORITY 2 371da177e4SLinus Torvalds 381da177e4SLinus Torvalds /* 398ee2767aSMilan Broz * Reserve 1MB for each snapshot initially (with minimum of 1 page). 401da177e4SLinus Torvalds */ 418ee2767aSMilan Broz #define SNAPSHOT_PAGES (((1UL << 20) >> PAGE_SHIFT) ? : 1) 421da177e4SLinus Torvalds 43cd45daffSMikulas Patocka /* 44cd45daffSMikulas Patocka * The size of the mempool used to track chunks in use. 45cd45daffSMikulas Patocka */ 46cd45daffSMikulas Patocka #define MIN_IOS 256 47cd45daffSMikulas Patocka 48ccc45ea8SJonathan Brassow #define DM_TRACKED_CHUNK_HASH_SIZE 16 49ccc45ea8SJonathan Brassow #define DM_TRACKED_CHUNK_HASH(x) ((unsigned long)(x) & \ 50ccc45ea8SJonathan Brassow (DM_TRACKED_CHUNK_HASH_SIZE - 1)) 51ccc45ea8SJonathan Brassow 52ccc45ea8SJonathan Brassow struct exception_table { 53ccc45ea8SJonathan Brassow uint32_t hash_mask; 54ccc45ea8SJonathan Brassow unsigned hash_shift; 55ccc45ea8SJonathan Brassow struct list_head *table; 56ccc45ea8SJonathan Brassow }; 57ccc45ea8SJonathan Brassow 58ccc45ea8SJonathan Brassow struct dm_snapshot { 59ccc45ea8SJonathan Brassow struct rw_semaphore lock; 60ccc45ea8SJonathan Brassow 61ccc45ea8SJonathan Brassow struct dm_dev *origin; 62ccc45ea8SJonathan Brassow 63ccc45ea8SJonathan Brassow /* List of snapshots per Origin */ 64ccc45ea8SJonathan Brassow struct list_head list; 65ccc45ea8SJonathan Brassow 66ccc45ea8SJonathan Brassow /* You can't use a snapshot if this is 0 (e.g. if full) */ 67ccc45ea8SJonathan Brassow int valid; 68ccc45ea8SJonathan Brassow 69ccc45ea8SJonathan Brassow /* Origin writes don't trigger exceptions until this is set */ 70ccc45ea8SJonathan Brassow int active; 71ccc45ea8SJonathan Brassow 72ccc45ea8SJonathan Brassow mempool_t *pending_pool; 73ccc45ea8SJonathan Brassow 74ccc45ea8SJonathan Brassow atomic_t pending_exceptions_count; 75ccc45ea8SJonathan Brassow 76ccc45ea8SJonathan Brassow struct exception_table pending; 77ccc45ea8SJonathan Brassow struct exception_table complete; 78ccc45ea8SJonathan Brassow 79ccc45ea8SJonathan Brassow /* 80ccc45ea8SJonathan Brassow * pe_lock protects all pending_exception operations and access 81ccc45ea8SJonathan Brassow * as well as the snapshot_bios list. 82ccc45ea8SJonathan Brassow */ 83ccc45ea8SJonathan Brassow spinlock_t pe_lock; 84ccc45ea8SJonathan Brassow 85ccc45ea8SJonathan Brassow /* The on disk metadata handler */ 86ccc45ea8SJonathan Brassow struct dm_exception_store *store; 87ccc45ea8SJonathan Brassow 88ccc45ea8SJonathan Brassow struct dm_kcopyd_client *kcopyd_client; 89ccc45ea8SJonathan Brassow 90ccc45ea8SJonathan Brassow /* Queue of snapshot writes for ksnapd to flush */ 91ccc45ea8SJonathan Brassow struct bio_list queued_bios; 92ccc45ea8SJonathan Brassow struct work_struct queued_bios_work; 93ccc45ea8SJonathan Brassow 94ccc45ea8SJonathan Brassow /* Chunks with outstanding reads */ 95ccc45ea8SJonathan Brassow mempool_t *tracked_chunk_pool; 96ccc45ea8SJonathan Brassow spinlock_t tracked_chunk_lock; 97ccc45ea8SJonathan Brassow struct hlist_head tracked_chunk_hash[DM_TRACKED_CHUNK_HASH_SIZE]; 98ccc45ea8SJonathan Brassow }; 99ccc45ea8SJonathan Brassow 100c642f9e0SAdrian Bunk static struct workqueue_struct *ksnapd; 101c4028958SDavid Howells static void flush_queued_bios(struct work_struct *work); 102ca3a931fSAlasdair G Kergon 103ccc45ea8SJonathan Brassow static sector_t chunk_to_sector(struct dm_exception_store *store, 104ccc45ea8SJonathan Brassow chunk_t chunk) 105ccc45ea8SJonathan Brassow { 106ccc45ea8SJonathan Brassow return chunk << store->chunk_shift; 107ccc45ea8SJonathan Brassow } 108ccc45ea8SJonathan Brassow 109ccc45ea8SJonathan Brassow static int bdev_equal(struct block_device *lhs, struct block_device *rhs) 110ccc45ea8SJonathan Brassow { 111ccc45ea8SJonathan Brassow /* 112ccc45ea8SJonathan Brassow * There is only ever one instance of a particular block 113ccc45ea8SJonathan Brassow * device so we can compare pointers safely. 114ccc45ea8SJonathan Brassow */ 115ccc45ea8SJonathan Brassow return lhs == rhs; 116ccc45ea8SJonathan Brassow } 117ccc45ea8SJonathan Brassow 118028867acSAlasdair G Kergon struct dm_snap_pending_exception { 1191d4989c8SJon Brassow struct dm_exception e; 1201da177e4SLinus Torvalds 1211da177e4SLinus Torvalds /* 1221da177e4SLinus Torvalds * Origin buffers waiting for this to complete are held 1231da177e4SLinus Torvalds * in a bio list 1241da177e4SLinus Torvalds */ 1251da177e4SLinus Torvalds struct bio_list origin_bios; 1261da177e4SLinus Torvalds struct bio_list snapshot_bios; 1271da177e4SLinus Torvalds 1281da177e4SLinus Torvalds /* 129eccf0817SAlasdair G Kergon * Short-term queue of pending exceptions prior to submission. 130eccf0817SAlasdair G Kergon */ 131eccf0817SAlasdair G Kergon struct list_head list; 132eccf0817SAlasdair G Kergon 133eccf0817SAlasdair G Kergon /* 134b4b610f6SAlasdair G Kergon * The primary pending_exception is the one that holds 1354b832e8dSAlasdair G Kergon * the ref_count and the list of origin_bios for a 136b4b610f6SAlasdair G Kergon * group of pending_exceptions. It is always last to get freed. 137b4b610f6SAlasdair G Kergon * These fields get set up when writing to the origin. 1381da177e4SLinus Torvalds */ 139028867acSAlasdair G Kergon struct dm_snap_pending_exception *primary_pe; 140b4b610f6SAlasdair G Kergon 141b4b610f6SAlasdair G Kergon /* 142b4b610f6SAlasdair G Kergon * Number of pending_exceptions processing this chunk. 143b4b610f6SAlasdair G Kergon * When this drops to zero we must complete the origin bios. 144b4b610f6SAlasdair G Kergon * If incrementing or decrementing this, hold pe->snap->lock for 145b4b610f6SAlasdair G Kergon * the sibling concerned and not pe->primary_pe->snap->lock unless 146b4b610f6SAlasdair G Kergon * they are the same. 147b4b610f6SAlasdair G Kergon */ 1484b832e8dSAlasdair G Kergon atomic_t ref_count; 1491da177e4SLinus Torvalds 1501da177e4SLinus Torvalds /* Pointer back to snapshot context */ 1511da177e4SLinus Torvalds struct dm_snapshot *snap; 1521da177e4SLinus Torvalds 1531da177e4SLinus Torvalds /* 1541da177e4SLinus Torvalds * 1 indicates the exception has already been sent to 1551da177e4SLinus Torvalds * kcopyd. 1561da177e4SLinus Torvalds */ 1571da177e4SLinus Torvalds int started; 1581da177e4SLinus Torvalds }; 1591da177e4SLinus Torvalds 1601da177e4SLinus Torvalds /* 1611da177e4SLinus Torvalds * Hash table mapping origin volumes to lists of snapshots and 1621da177e4SLinus Torvalds * a lock to protect it 1631da177e4SLinus Torvalds */ 164e18b890bSChristoph Lameter static struct kmem_cache *exception_cache; 165e18b890bSChristoph Lameter static struct kmem_cache *pending_cache; 1661da177e4SLinus Torvalds 167cd45daffSMikulas Patocka struct dm_snap_tracked_chunk { 168cd45daffSMikulas Patocka struct hlist_node node; 169cd45daffSMikulas Patocka chunk_t chunk; 170cd45daffSMikulas Patocka }; 171cd45daffSMikulas Patocka 172cd45daffSMikulas Patocka static struct kmem_cache *tracked_chunk_cache; 173cd45daffSMikulas Patocka 174cd45daffSMikulas Patocka static struct dm_snap_tracked_chunk *track_chunk(struct dm_snapshot *s, 175cd45daffSMikulas Patocka chunk_t chunk) 176cd45daffSMikulas Patocka { 177cd45daffSMikulas Patocka struct dm_snap_tracked_chunk *c = mempool_alloc(s->tracked_chunk_pool, 178cd45daffSMikulas Patocka GFP_NOIO); 179cd45daffSMikulas Patocka unsigned long flags; 180cd45daffSMikulas Patocka 181cd45daffSMikulas Patocka c->chunk = chunk; 182cd45daffSMikulas Patocka 183cd45daffSMikulas Patocka spin_lock_irqsave(&s->tracked_chunk_lock, flags); 184cd45daffSMikulas Patocka hlist_add_head(&c->node, 185cd45daffSMikulas Patocka &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)]); 186cd45daffSMikulas Patocka spin_unlock_irqrestore(&s->tracked_chunk_lock, flags); 187cd45daffSMikulas Patocka 188cd45daffSMikulas Patocka return c; 189cd45daffSMikulas Patocka } 190cd45daffSMikulas Patocka 191cd45daffSMikulas Patocka static void stop_tracking_chunk(struct dm_snapshot *s, 192cd45daffSMikulas Patocka struct dm_snap_tracked_chunk *c) 193cd45daffSMikulas Patocka { 194cd45daffSMikulas Patocka unsigned long flags; 195cd45daffSMikulas Patocka 196cd45daffSMikulas Patocka spin_lock_irqsave(&s->tracked_chunk_lock, flags); 197cd45daffSMikulas Patocka hlist_del(&c->node); 198cd45daffSMikulas Patocka spin_unlock_irqrestore(&s->tracked_chunk_lock, flags); 199cd45daffSMikulas Patocka 200cd45daffSMikulas Patocka mempool_free(c, s->tracked_chunk_pool); 201cd45daffSMikulas Patocka } 202cd45daffSMikulas Patocka 203a8d41b59SMikulas Patocka static int __chunk_is_tracked(struct dm_snapshot *s, chunk_t chunk) 204a8d41b59SMikulas Patocka { 205a8d41b59SMikulas Patocka struct dm_snap_tracked_chunk *c; 206a8d41b59SMikulas Patocka struct hlist_node *hn; 207a8d41b59SMikulas Patocka int found = 0; 208a8d41b59SMikulas Patocka 209a8d41b59SMikulas Patocka spin_lock_irq(&s->tracked_chunk_lock); 210a8d41b59SMikulas Patocka 211a8d41b59SMikulas Patocka hlist_for_each_entry(c, hn, 212a8d41b59SMikulas Patocka &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)], node) { 213a8d41b59SMikulas Patocka if (c->chunk == chunk) { 214a8d41b59SMikulas Patocka found = 1; 215a8d41b59SMikulas Patocka break; 216a8d41b59SMikulas Patocka } 217a8d41b59SMikulas Patocka } 218a8d41b59SMikulas Patocka 219a8d41b59SMikulas Patocka spin_unlock_irq(&s->tracked_chunk_lock); 220a8d41b59SMikulas Patocka 221a8d41b59SMikulas Patocka return found; 222a8d41b59SMikulas Patocka } 223a8d41b59SMikulas Patocka 2241da177e4SLinus Torvalds /* 2251da177e4SLinus Torvalds * One of these per registered origin, held in the snapshot_origins hash 2261da177e4SLinus Torvalds */ 2271da177e4SLinus Torvalds struct origin { 2281da177e4SLinus Torvalds /* The origin device */ 2291da177e4SLinus Torvalds struct block_device *bdev; 2301da177e4SLinus Torvalds 2311da177e4SLinus Torvalds struct list_head hash_list; 2321da177e4SLinus Torvalds 2331da177e4SLinus Torvalds /* List of snapshots for this origin */ 2341da177e4SLinus Torvalds struct list_head snapshots; 2351da177e4SLinus Torvalds }; 2361da177e4SLinus Torvalds 2371da177e4SLinus Torvalds /* 2381da177e4SLinus Torvalds * Size of the hash table for origin volumes. If we make this 2391da177e4SLinus Torvalds * the size of the minors list then it should be nearly perfect 2401da177e4SLinus Torvalds */ 2411da177e4SLinus Torvalds #define ORIGIN_HASH_SIZE 256 2421da177e4SLinus Torvalds #define ORIGIN_MASK 0xFF 2431da177e4SLinus Torvalds static struct list_head *_origins; 2441da177e4SLinus Torvalds static struct rw_semaphore _origins_lock; 2451da177e4SLinus Torvalds 2461da177e4SLinus Torvalds static int init_origin_hash(void) 2471da177e4SLinus Torvalds { 2481da177e4SLinus Torvalds int i; 2491da177e4SLinus Torvalds 2501da177e4SLinus Torvalds _origins = kmalloc(ORIGIN_HASH_SIZE * sizeof(struct list_head), 2511da177e4SLinus Torvalds GFP_KERNEL); 2521da177e4SLinus Torvalds if (!_origins) { 25372d94861SAlasdair G Kergon DMERR("unable to allocate memory"); 2541da177e4SLinus Torvalds return -ENOMEM; 2551da177e4SLinus Torvalds } 2561da177e4SLinus Torvalds 2571da177e4SLinus Torvalds for (i = 0; i < ORIGIN_HASH_SIZE; i++) 2581da177e4SLinus Torvalds INIT_LIST_HEAD(_origins + i); 2591da177e4SLinus Torvalds init_rwsem(&_origins_lock); 2601da177e4SLinus Torvalds 2611da177e4SLinus Torvalds return 0; 2621da177e4SLinus Torvalds } 2631da177e4SLinus Torvalds 2641da177e4SLinus Torvalds static void exit_origin_hash(void) 2651da177e4SLinus Torvalds { 2661da177e4SLinus Torvalds kfree(_origins); 2671da177e4SLinus Torvalds } 2681da177e4SLinus Torvalds 269028867acSAlasdair G Kergon static unsigned origin_hash(struct block_device *bdev) 2701da177e4SLinus Torvalds { 2711da177e4SLinus Torvalds return bdev->bd_dev & ORIGIN_MASK; 2721da177e4SLinus Torvalds } 2731da177e4SLinus Torvalds 2741da177e4SLinus Torvalds static struct origin *__lookup_origin(struct block_device *origin) 2751da177e4SLinus Torvalds { 2761da177e4SLinus Torvalds struct list_head *ol; 2771da177e4SLinus Torvalds struct origin *o; 2781da177e4SLinus Torvalds 2791da177e4SLinus Torvalds ol = &_origins[origin_hash(origin)]; 2801da177e4SLinus Torvalds list_for_each_entry (o, ol, hash_list) 2811da177e4SLinus Torvalds if (bdev_equal(o->bdev, origin)) 2821da177e4SLinus Torvalds return o; 2831da177e4SLinus Torvalds 2841da177e4SLinus Torvalds return NULL; 2851da177e4SLinus Torvalds } 2861da177e4SLinus Torvalds 2871da177e4SLinus Torvalds static void __insert_origin(struct origin *o) 2881da177e4SLinus Torvalds { 2891da177e4SLinus Torvalds struct list_head *sl = &_origins[origin_hash(o->bdev)]; 2901da177e4SLinus Torvalds list_add_tail(&o->hash_list, sl); 2911da177e4SLinus Torvalds } 2921da177e4SLinus Torvalds 2931da177e4SLinus Torvalds /* 2941da177e4SLinus Torvalds * Make a note of the snapshot and its origin so we can look it 2951da177e4SLinus Torvalds * up when the origin has a write on it. 2961da177e4SLinus Torvalds */ 2971da177e4SLinus Torvalds static int register_snapshot(struct dm_snapshot *snap) 2981da177e4SLinus Torvalds { 2996d45d93eSMikulas Patocka struct dm_snapshot *l; 30060c856c8SMikulas Patocka struct origin *o, *new_o; 3011da177e4SLinus Torvalds struct block_device *bdev = snap->origin->bdev; 3021da177e4SLinus Torvalds 30360c856c8SMikulas Patocka new_o = kmalloc(sizeof(*new_o), GFP_KERNEL); 30460c856c8SMikulas Patocka if (!new_o) 30560c856c8SMikulas Patocka return -ENOMEM; 30660c856c8SMikulas Patocka 3071da177e4SLinus Torvalds down_write(&_origins_lock); 3081da177e4SLinus Torvalds o = __lookup_origin(bdev); 3091da177e4SLinus Torvalds 31060c856c8SMikulas Patocka if (o) 31160c856c8SMikulas Patocka kfree(new_o); 31260c856c8SMikulas Patocka else { 3131da177e4SLinus Torvalds /* New origin */ 31460c856c8SMikulas Patocka o = new_o; 3151da177e4SLinus Torvalds 3161da177e4SLinus Torvalds /* Initialise the struct */ 3171da177e4SLinus Torvalds INIT_LIST_HEAD(&o->snapshots); 3181da177e4SLinus Torvalds o->bdev = bdev; 3191da177e4SLinus Torvalds 3201da177e4SLinus Torvalds __insert_origin(o); 3211da177e4SLinus Torvalds } 3221da177e4SLinus Torvalds 3236d45d93eSMikulas Patocka /* Sort the list according to chunk size, largest-first smallest-last */ 3246d45d93eSMikulas Patocka list_for_each_entry(l, &o->snapshots, list) 3256d45d93eSMikulas Patocka if (l->store->chunk_size < snap->store->chunk_size) 3266d45d93eSMikulas Patocka break; 3276d45d93eSMikulas Patocka list_add_tail(&snap->list, &l->list); 3281da177e4SLinus Torvalds 3291da177e4SLinus Torvalds up_write(&_origins_lock); 3301da177e4SLinus Torvalds return 0; 3311da177e4SLinus Torvalds } 3321da177e4SLinus Torvalds 3331da177e4SLinus Torvalds static void unregister_snapshot(struct dm_snapshot *s) 3341da177e4SLinus Torvalds { 3351da177e4SLinus Torvalds struct origin *o; 3361da177e4SLinus Torvalds 3371da177e4SLinus Torvalds down_write(&_origins_lock); 3381da177e4SLinus Torvalds o = __lookup_origin(s->origin->bdev); 3391da177e4SLinus Torvalds 3401da177e4SLinus Torvalds list_del(&s->list); 3411da177e4SLinus Torvalds if (list_empty(&o->snapshots)) { 3421da177e4SLinus Torvalds list_del(&o->hash_list); 3431da177e4SLinus Torvalds kfree(o); 3441da177e4SLinus Torvalds } 3451da177e4SLinus Torvalds 3461da177e4SLinus Torvalds up_write(&_origins_lock); 3471da177e4SLinus Torvalds } 3481da177e4SLinus Torvalds 3491da177e4SLinus Torvalds /* 3501da177e4SLinus Torvalds * Implementation of the exception hash tables. 351d74f81f8SMilan Broz * The lowest hash_shift bits of the chunk number are ignored, allowing 352d74f81f8SMilan Broz * some consecutive chunks to be grouped together. 3531da177e4SLinus Torvalds */ 354d74f81f8SMilan Broz static int init_exception_table(struct exception_table *et, uint32_t size, 355d74f81f8SMilan Broz unsigned hash_shift) 3561da177e4SLinus Torvalds { 3571da177e4SLinus Torvalds unsigned int i; 3581da177e4SLinus Torvalds 359d74f81f8SMilan Broz et->hash_shift = hash_shift; 3601da177e4SLinus Torvalds et->hash_mask = size - 1; 3611da177e4SLinus Torvalds et->table = dm_vcalloc(size, sizeof(struct list_head)); 3621da177e4SLinus Torvalds if (!et->table) 3631da177e4SLinus Torvalds return -ENOMEM; 3641da177e4SLinus Torvalds 3651da177e4SLinus Torvalds for (i = 0; i < size; i++) 3661da177e4SLinus Torvalds INIT_LIST_HEAD(et->table + i); 3671da177e4SLinus Torvalds 3681da177e4SLinus Torvalds return 0; 3691da177e4SLinus Torvalds } 3701da177e4SLinus Torvalds 371e18b890bSChristoph Lameter static void exit_exception_table(struct exception_table *et, struct kmem_cache *mem) 3721da177e4SLinus Torvalds { 3731da177e4SLinus Torvalds struct list_head *slot; 3741d4989c8SJon Brassow struct dm_exception *ex, *next; 3751da177e4SLinus Torvalds int i, size; 3761da177e4SLinus Torvalds 3771da177e4SLinus Torvalds size = et->hash_mask + 1; 3781da177e4SLinus Torvalds for (i = 0; i < size; i++) { 3791da177e4SLinus Torvalds slot = et->table + i; 3801da177e4SLinus Torvalds 3811da177e4SLinus Torvalds list_for_each_entry_safe (ex, next, slot, hash_list) 3821da177e4SLinus Torvalds kmem_cache_free(mem, ex); 3831da177e4SLinus Torvalds } 3841da177e4SLinus Torvalds 3851da177e4SLinus Torvalds vfree(et->table); 3861da177e4SLinus Torvalds } 3871da177e4SLinus Torvalds 388028867acSAlasdair G Kergon static uint32_t exception_hash(struct exception_table *et, chunk_t chunk) 3891da177e4SLinus Torvalds { 390d74f81f8SMilan Broz return (chunk >> et->hash_shift) & et->hash_mask; 3911da177e4SLinus Torvalds } 3921da177e4SLinus Torvalds 3931d4989c8SJon Brassow static void remove_exception(struct dm_exception *e) 3941da177e4SLinus Torvalds { 3951da177e4SLinus Torvalds list_del(&e->hash_list); 3961da177e4SLinus Torvalds } 3971da177e4SLinus Torvalds 3981da177e4SLinus Torvalds /* 3991da177e4SLinus Torvalds * Return the exception data for a sector, or NULL if not 4001da177e4SLinus Torvalds * remapped. 4011da177e4SLinus Torvalds */ 4021d4989c8SJon Brassow static struct dm_exception *lookup_exception(struct exception_table *et, 4031da177e4SLinus Torvalds chunk_t chunk) 4041da177e4SLinus Torvalds { 4051da177e4SLinus Torvalds struct list_head *slot; 4061d4989c8SJon Brassow struct dm_exception *e; 4071da177e4SLinus Torvalds 4081da177e4SLinus Torvalds slot = &et->table[exception_hash(et, chunk)]; 4091da177e4SLinus Torvalds list_for_each_entry (e, slot, hash_list) 410d74f81f8SMilan Broz if (chunk >= e->old_chunk && 411d74f81f8SMilan Broz chunk <= e->old_chunk + dm_consecutive_chunk_count(e)) 4121da177e4SLinus Torvalds return e; 4131da177e4SLinus Torvalds 4141da177e4SLinus Torvalds return NULL; 4151da177e4SLinus Torvalds } 4161da177e4SLinus Torvalds 4171d4989c8SJon Brassow static struct dm_exception *alloc_exception(void) 4181da177e4SLinus Torvalds { 4191d4989c8SJon Brassow struct dm_exception *e; 4201da177e4SLinus Torvalds 4211da177e4SLinus Torvalds e = kmem_cache_alloc(exception_cache, GFP_NOIO); 4221da177e4SLinus Torvalds if (!e) 4231da177e4SLinus Torvalds e = kmem_cache_alloc(exception_cache, GFP_ATOMIC); 4241da177e4SLinus Torvalds 4251da177e4SLinus Torvalds return e; 4261da177e4SLinus Torvalds } 4271da177e4SLinus Torvalds 4281d4989c8SJon Brassow static void free_exception(struct dm_exception *e) 4291da177e4SLinus Torvalds { 4301da177e4SLinus Torvalds kmem_cache_free(exception_cache, e); 4311da177e4SLinus Torvalds } 4321da177e4SLinus Torvalds 43392e86812SMikulas Patocka static struct dm_snap_pending_exception *alloc_pending_exception(struct dm_snapshot *s) 4341da177e4SLinus Torvalds { 43592e86812SMikulas Patocka struct dm_snap_pending_exception *pe = mempool_alloc(s->pending_pool, 43692e86812SMikulas Patocka GFP_NOIO); 43792e86812SMikulas Patocka 438879129d2SMikulas Patocka atomic_inc(&s->pending_exceptions_count); 43992e86812SMikulas Patocka pe->snap = s; 44092e86812SMikulas Patocka 44192e86812SMikulas Patocka return pe; 4421da177e4SLinus Torvalds } 4431da177e4SLinus Torvalds 444028867acSAlasdair G Kergon static void free_pending_exception(struct dm_snap_pending_exception *pe) 4451da177e4SLinus Torvalds { 446879129d2SMikulas Patocka struct dm_snapshot *s = pe->snap; 447879129d2SMikulas Patocka 448879129d2SMikulas Patocka mempool_free(pe, s->pending_pool); 449879129d2SMikulas Patocka smp_mb__before_atomic_dec(); 450879129d2SMikulas Patocka atomic_dec(&s->pending_exceptions_count); 4511da177e4SLinus Torvalds } 4521da177e4SLinus Torvalds 453d32a6ea6SJon Brassow static void insert_exception(struct exception_table *eh, 4541d4989c8SJon Brassow struct dm_exception *new_e) 455d74f81f8SMilan Broz { 456d74f81f8SMilan Broz struct list_head *l; 4571d4989c8SJon Brassow struct dm_exception *e = NULL; 458d74f81f8SMilan Broz 459d74f81f8SMilan Broz l = &eh->table[exception_hash(eh, new_e->old_chunk)]; 460d74f81f8SMilan Broz 461d74f81f8SMilan Broz /* Add immediately if this table doesn't support consecutive chunks */ 462d74f81f8SMilan Broz if (!eh->hash_shift) 463d74f81f8SMilan Broz goto out; 464d74f81f8SMilan Broz 465d74f81f8SMilan Broz /* List is ordered by old_chunk */ 466d74f81f8SMilan Broz list_for_each_entry_reverse(e, l, hash_list) { 467d74f81f8SMilan Broz /* Insert after an existing chunk? */ 468d74f81f8SMilan Broz if (new_e->old_chunk == (e->old_chunk + 469d74f81f8SMilan Broz dm_consecutive_chunk_count(e) + 1) && 470d74f81f8SMilan Broz new_e->new_chunk == (dm_chunk_number(e->new_chunk) + 471d74f81f8SMilan Broz dm_consecutive_chunk_count(e) + 1)) { 472d74f81f8SMilan Broz dm_consecutive_chunk_count_inc(e); 473d74f81f8SMilan Broz free_exception(new_e); 474d74f81f8SMilan Broz return; 475d74f81f8SMilan Broz } 476d74f81f8SMilan Broz 477d74f81f8SMilan Broz /* Insert before an existing chunk? */ 478d74f81f8SMilan Broz if (new_e->old_chunk == (e->old_chunk - 1) && 479d74f81f8SMilan Broz new_e->new_chunk == (dm_chunk_number(e->new_chunk) - 1)) { 480d74f81f8SMilan Broz dm_consecutive_chunk_count_inc(e); 481d74f81f8SMilan Broz e->old_chunk--; 482d74f81f8SMilan Broz e->new_chunk--; 483d74f81f8SMilan Broz free_exception(new_e); 484d74f81f8SMilan Broz return; 485d74f81f8SMilan Broz } 486d74f81f8SMilan Broz 487d74f81f8SMilan Broz if (new_e->old_chunk > e->old_chunk) 488d74f81f8SMilan Broz break; 489d74f81f8SMilan Broz } 490d74f81f8SMilan Broz 491d74f81f8SMilan Broz out: 492d74f81f8SMilan Broz list_add(&new_e->hash_list, e ? &e->hash_list : l); 493d74f81f8SMilan Broz } 494d74f81f8SMilan Broz 495a159c1acSJonathan Brassow /* 496a159c1acSJonathan Brassow * Callback used by the exception stores to load exceptions when 497a159c1acSJonathan Brassow * initialising. 498a159c1acSJonathan Brassow */ 499a159c1acSJonathan Brassow static int dm_add_exception(void *context, chunk_t old, chunk_t new) 5001da177e4SLinus Torvalds { 501a159c1acSJonathan Brassow struct dm_snapshot *s = context; 5021d4989c8SJon Brassow struct dm_exception *e; 5031da177e4SLinus Torvalds 5041da177e4SLinus Torvalds e = alloc_exception(); 5051da177e4SLinus Torvalds if (!e) 5061da177e4SLinus Torvalds return -ENOMEM; 5071da177e4SLinus Torvalds 5081da177e4SLinus Torvalds e->old_chunk = old; 509d74f81f8SMilan Broz 510d74f81f8SMilan Broz /* Consecutive_count is implicitly initialised to zero */ 5111da177e4SLinus Torvalds e->new_chunk = new; 512d74f81f8SMilan Broz 513d32a6ea6SJon Brassow insert_exception(&s->complete, e); 514d74f81f8SMilan Broz 5151da177e4SLinus Torvalds return 0; 5161da177e4SLinus Torvalds } 5171da177e4SLinus Torvalds 5187e201b35SMikulas Patocka #define min_not_zero(l, r) (((l) == 0) ? (r) : (((r) == 0) ? (l) : min(l, r))) 5197e201b35SMikulas Patocka 5207e201b35SMikulas Patocka /* 5217e201b35SMikulas Patocka * Return a minimum chunk size of all snapshots that have the specified origin. 5227e201b35SMikulas Patocka * Return zero if the origin has no snapshots. 5237e201b35SMikulas Patocka */ 5247e201b35SMikulas Patocka static sector_t __minimum_chunk_size(struct origin *o) 5257e201b35SMikulas Patocka { 5267e201b35SMikulas Patocka struct dm_snapshot *snap; 5277e201b35SMikulas Patocka unsigned chunk_size = 0; 5287e201b35SMikulas Patocka 5297e201b35SMikulas Patocka if (o) 5307e201b35SMikulas Patocka list_for_each_entry(snap, &o->snapshots, list) 5317e201b35SMikulas Patocka chunk_size = min_not_zero(chunk_size, 5327e201b35SMikulas Patocka snap->store->chunk_size); 5337e201b35SMikulas Patocka 5347e201b35SMikulas Patocka return chunk_size; 5357e201b35SMikulas Patocka } 5367e201b35SMikulas Patocka 5371da177e4SLinus Torvalds /* 5381da177e4SLinus Torvalds * Hard coded magic. 5391da177e4SLinus Torvalds */ 5401da177e4SLinus Torvalds static int calc_max_buckets(void) 5411da177e4SLinus Torvalds { 5421da177e4SLinus Torvalds /* use a fixed size of 2MB */ 5431da177e4SLinus Torvalds unsigned long mem = 2 * 1024 * 1024; 5441da177e4SLinus Torvalds mem /= sizeof(struct list_head); 5451da177e4SLinus Torvalds 5461da177e4SLinus Torvalds return mem; 5471da177e4SLinus Torvalds } 5481da177e4SLinus Torvalds 5491da177e4SLinus Torvalds /* 5501da177e4SLinus Torvalds * Allocate room for a suitable hash table. 5511da177e4SLinus Torvalds */ 552fee1998eSJonathan Brassow static int init_hash_tables(struct dm_snapshot *s) 5531da177e4SLinus Torvalds { 5541da177e4SLinus Torvalds sector_t hash_size, cow_dev_size, origin_dev_size, max_buckets; 5551da177e4SLinus Torvalds 5561da177e4SLinus Torvalds /* 5571da177e4SLinus Torvalds * Calculate based on the size of the original volume or 5581da177e4SLinus Torvalds * the COW volume... 5591da177e4SLinus Torvalds */ 560fee1998eSJonathan Brassow cow_dev_size = get_dev_size(s->store->cow->bdev); 5611da177e4SLinus Torvalds origin_dev_size = get_dev_size(s->origin->bdev); 5621da177e4SLinus Torvalds max_buckets = calc_max_buckets(); 5631da177e4SLinus Torvalds 564fee1998eSJonathan Brassow hash_size = min(origin_dev_size, cow_dev_size) >> s->store->chunk_shift; 5651da177e4SLinus Torvalds hash_size = min(hash_size, max_buckets); 5661da177e4SLinus Torvalds 5678e87b9b8SMikulas Patocka if (hash_size < 64) 5688e87b9b8SMikulas Patocka hash_size = 64; 5698defd830SRobert P. J. Day hash_size = rounddown_pow_of_two(hash_size); 570d74f81f8SMilan Broz if (init_exception_table(&s->complete, hash_size, 571d74f81f8SMilan Broz DM_CHUNK_CONSECUTIVE_BITS)) 5721da177e4SLinus Torvalds return -ENOMEM; 5731da177e4SLinus Torvalds 5741da177e4SLinus Torvalds /* 5751da177e4SLinus Torvalds * Allocate hash table for in-flight exceptions 5761da177e4SLinus Torvalds * Make this smaller than the real hash table 5771da177e4SLinus Torvalds */ 5781da177e4SLinus Torvalds hash_size >>= 3; 5791da177e4SLinus Torvalds if (hash_size < 64) 5801da177e4SLinus Torvalds hash_size = 64; 5811da177e4SLinus Torvalds 582d74f81f8SMilan Broz if (init_exception_table(&s->pending, hash_size, 0)) { 5831da177e4SLinus Torvalds exit_exception_table(&s->complete, exception_cache); 5841da177e4SLinus Torvalds return -ENOMEM; 5851da177e4SLinus Torvalds } 5861da177e4SLinus Torvalds 5871da177e4SLinus Torvalds return 0; 5881da177e4SLinus Torvalds } 5891da177e4SLinus Torvalds 5901da177e4SLinus Torvalds /* 5911da177e4SLinus Torvalds * Construct a snapshot mapping: <origin_dev> <COW-dev> <p/n> <chunk-size> 5921da177e4SLinus Torvalds */ 5931da177e4SLinus Torvalds static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv) 5941da177e4SLinus Torvalds { 5951da177e4SLinus Torvalds struct dm_snapshot *s; 596cd45daffSMikulas Patocka int i; 5971da177e4SLinus Torvalds int r = -EINVAL; 5981da177e4SLinus Torvalds char *origin_path; 599fee1998eSJonathan Brassow struct dm_exception_store *store; 600fee1998eSJonathan Brassow unsigned args_used; 6011da177e4SLinus Torvalds 6024c7e3bf4SMark McLoughlin if (argc != 4) { 60372d94861SAlasdair G Kergon ti->error = "requires exactly 4 arguments"; 6041da177e4SLinus Torvalds r = -EINVAL; 605fee1998eSJonathan Brassow goto bad_args; 6061da177e4SLinus Torvalds } 6071da177e4SLinus Torvalds 6081da177e4SLinus Torvalds origin_path = argv[0]; 609fee1998eSJonathan Brassow argv++; 610fee1998eSJonathan Brassow argc--; 6111da177e4SLinus Torvalds 612fee1998eSJonathan Brassow r = dm_exception_store_create(ti, argc, argv, &args_used, &store); 613fee1998eSJonathan Brassow if (r) { 614fee1998eSJonathan Brassow ti->error = "Couldn't create exception store"; 6151da177e4SLinus Torvalds r = -EINVAL; 616fee1998eSJonathan Brassow goto bad_args; 6171da177e4SLinus Torvalds } 6181da177e4SLinus Torvalds 619fee1998eSJonathan Brassow argv += args_used; 620fee1998eSJonathan Brassow argc -= args_used; 621fee1998eSJonathan Brassow 6221da177e4SLinus Torvalds s = kmalloc(sizeof(*s), GFP_KERNEL); 623fee1998eSJonathan Brassow if (!s) { 6241da177e4SLinus Torvalds ti->error = "Cannot allocate snapshot context private " 6251da177e4SLinus Torvalds "structure"; 6261da177e4SLinus Torvalds r = -ENOMEM; 627fee1998eSJonathan Brassow goto bad_snap; 6281da177e4SLinus Torvalds } 6291da177e4SLinus Torvalds 6301da177e4SLinus Torvalds r = dm_get_device(ti, origin_path, 0, ti->len, FMODE_READ, &s->origin); 6311da177e4SLinus Torvalds if (r) { 6321da177e4SLinus Torvalds ti->error = "Cannot get origin device"; 633fee1998eSJonathan Brassow goto bad_origin; 6341da177e4SLinus Torvalds } 6351da177e4SLinus Torvalds 636fee1998eSJonathan Brassow s->store = store; 6371da177e4SLinus Torvalds s->valid = 1; 638aa14edebSAlasdair G Kergon s->active = 0; 639879129d2SMikulas Patocka atomic_set(&s->pending_exceptions_count, 0); 6401da177e4SLinus Torvalds init_rwsem(&s->lock); 641ca3a931fSAlasdair G Kergon spin_lock_init(&s->pe_lock); 6421da177e4SLinus Torvalds 6431da177e4SLinus Torvalds /* Allocate hash table for COW data */ 644fee1998eSJonathan Brassow if (init_hash_tables(s)) { 6451da177e4SLinus Torvalds ti->error = "Unable to allocate hash table space"; 6461da177e4SLinus Torvalds r = -ENOMEM; 647fee1998eSJonathan Brassow goto bad_hash_tables; 6481da177e4SLinus Torvalds } 6491da177e4SLinus Torvalds 650eb69aca5SHeinz Mauelshagen r = dm_kcopyd_client_create(SNAPSHOT_PAGES, &s->kcopyd_client); 6511da177e4SLinus Torvalds if (r) { 6521da177e4SLinus Torvalds ti->error = "Could not create kcopyd client"; 653fee1998eSJonathan Brassow goto bad_kcopyd; 6541da177e4SLinus Torvalds } 6551da177e4SLinus Torvalds 65692e86812SMikulas Patocka s->pending_pool = mempool_create_slab_pool(MIN_IOS, pending_cache); 65792e86812SMikulas Patocka if (!s->pending_pool) { 65892e86812SMikulas Patocka ti->error = "Could not allocate mempool for pending exceptions"; 659fee1998eSJonathan Brassow goto bad_pending_pool; 66092e86812SMikulas Patocka } 66192e86812SMikulas Patocka 662cd45daffSMikulas Patocka s->tracked_chunk_pool = mempool_create_slab_pool(MIN_IOS, 663cd45daffSMikulas Patocka tracked_chunk_cache); 664cd45daffSMikulas Patocka if (!s->tracked_chunk_pool) { 665cd45daffSMikulas Patocka ti->error = "Could not allocate tracked_chunk mempool for " 666cd45daffSMikulas Patocka "tracking reads"; 66792e86812SMikulas Patocka goto bad_tracked_chunk_pool; 668cd45daffSMikulas Patocka } 669cd45daffSMikulas Patocka 670cd45daffSMikulas Patocka for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) 671cd45daffSMikulas Patocka INIT_HLIST_HEAD(&s->tracked_chunk_hash[i]); 672cd45daffSMikulas Patocka 673cd45daffSMikulas Patocka spin_lock_init(&s->tracked_chunk_lock); 674cd45daffSMikulas Patocka 675aa14edebSAlasdair G Kergon /* Metadata must only be loaded into one table at once */ 676493df71cSJonathan Brassow r = s->store->type->read_metadata(s->store, dm_add_exception, 677493df71cSJonathan Brassow (void *)s); 6780764147bSMilan Broz if (r < 0) { 679f9cea4f7SMark McLoughlin ti->error = "Failed to read snapshot metadata"; 680cd45daffSMikulas Patocka goto bad_load_and_register; 6810764147bSMilan Broz } else if (r > 0) { 6820764147bSMilan Broz s->valid = 0; 6830764147bSMilan Broz DMWARN("Snapshot is marked invalid."); 684f9cea4f7SMark McLoughlin } 685aa14edebSAlasdair G Kergon 686ca3a931fSAlasdair G Kergon bio_list_init(&s->queued_bios); 687c4028958SDavid Howells INIT_WORK(&s->queued_bios_work, flush_queued_bios); 688ca3a931fSAlasdair G Kergon 6893f2412dcSMikulas Patocka if (!s->store->chunk_size) { 6903f2412dcSMikulas Patocka ti->error = "Chunk size not set"; 6913f2412dcSMikulas Patocka goto bad_load_and_register; 6923f2412dcSMikulas Patocka } 6933f2412dcSMikulas Patocka 6941da177e4SLinus Torvalds /* Add snapshot to the list of snapshots for this origin */ 695aa14edebSAlasdair G Kergon /* Exceptions aren't triggered till snapshot_resume() is called */ 6961da177e4SLinus Torvalds if (register_snapshot(s)) { 6971da177e4SLinus Torvalds r = -EINVAL; 6981da177e4SLinus Torvalds ti->error = "Cannot register snapshot origin"; 699cd45daffSMikulas Patocka goto bad_load_and_register; 7001da177e4SLinus Torvalds } 7011da177e4SLinus Torvalds 7021da177e4SLinus Torvalds ti->private = s; 703d0216849SJonathan Brassow ti->split_io = s->store->chunk_size; 704494b3ee7SMikulas Patocka ti->num_flush_requests = 1; 7051da177e4SLinus Torvalds 7061da177e4SLinus Torvalds return 0; 7071da177e4SLinus Torvalds 708cd45daffSMikulas Patocka bad_load_and_register: 709cd45daffSMikulas Patocka mempool_destroy(s->tracked_chunk_pool); 710cd45daffSMikulas Patocka 71192e86812SMikulas Patocka bad_tracked_chunk_pool: 71292e86812SMikulas Patocka mempool_destroy(s->pending_pool); 71392e86812SMikulas Patocka 714fee1998eSJonathan Brassow bad_pending_pool: 715eb69aca5SHeinz Mauelshagen dm_kcopyd_client_destroy(s->kcopyd_client); 7161da177e4SLinus Torvalds 717fee1998eSJonathan Brassow bad_kcopyd: 7181da177e4SLinus Torvalds exit_exception_table(&s->pending, pending_cache); 7191da177e4SLinus Torvalds exit_exception_table(&s->complete, exception_cache); 7201da177e4SLinus Torvalds 721fee1998eSJonathan Brassow bad_hash_tables: 7221da177e4SLinus Torvalds dm_put_device(ti, s->origin); 7231da177e4SLinus Torvalds 724fee1998eSJonathan Brassow bad_origin: 7251da177e4SLinus Torvalds kfree(s); 7261da177e4SLinus Torvalds 727fee1998eSJonathan Brassow bad_snap: 728fee1998eSJonathan Brassow dm_exception_store_destroy(store); 729fee1998eSJonathan Brassow 730fee1998eSJonathan Brassow bad_args: 7311da177e4SLinus Torvalds return r; 7321da177e4SLinus Torvalds } 7331da177e4SLinus Torvalds 73431c93a0cSMilan Broz static void __free_exceptions(struct dm_snapshot *s) 73531c93a0cSMilan Broz { 736eb69aca5SHeinz Mauelshagen dm_kcopyd_client_destroy(s->kcopyd_client); 73731c93a0cSMilan Broz s->kcopyd_client = NULL; 73831c93a0cSMilan Broz 73931c93a0cSMilan Broz exit_exception_table(&s->pending, pending_cache); 74031c93a0cSMilan Broz exit_exception_table(&s->complete, exception_cache); 74131c93a0cSMilan Broz } 74231c93a0cSMilan Broz 7431da177e4SLinus Torvalds static void snapshot_dtr(struct dm_target *ti) 7441da177e4SLinus Torvalds { 745cd45daffSMikulas Patocka #ifdef CONFIG_DM_DEBUG 746cd45daffSMikulas Patocka int i; 747cd45daffSMikulas Patocka #endif 748028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 7491da177e4SLinus Torvalds 750ca3a931fSAlasdair G Kergon flush_workqueue(ksnapd); 751ca3a931fSAlasdair G Kergon 752138728dcSAlasdair G Kergon /* Prevent further origin writes from using this snapshot. */ 753138728dcSAlasdair G Kergon /* After this returns there can be no new kcopyd jobs. */ 7541da177e4SLinus Torvalds unregister_snapshot(s); 7551da177e4SLinus Torvalds 756879129d2SMikulas Patocka while (atomic_read(&s->pending_exceptions_count)) 75790fa1527SMikulas Patocka msleep(1); 758879129d2SMikulas Patocka /* 759879129d2SMikulas Patocka * Ensure instructions in mempool_destroy aren't reordered 760879129d2SMikulas Patocka * before atomic_read. 761879129d2SMikulas Patocka */ 762879129d2SMikulas Patocka smp_mb(); 763879129d2SMikulas Patocka 764cd45daffSMikulas Patocka #ifdef CONFIG_DM_DEBUG 765cd45daffSMikulas Patocka for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) 766cd45daffSMikulas Patocka BUG_ON(!hlist_empty(&s->tracked_chunk_hash[i])); 767cd45daffSMikulas Patocka #endif 768cd45daffSMikulas Patocka 769cd45daffSMikulas Patocka mempool_destroy(s->tracked_chunk_pool); 770cd45daffSMikulas Patocka 77131c93a0cSMilan Broz __free_exceptions(s); 7721da177e4SLinus Torvalds 77392e86812SMikulas Patocka mempool_destroy(s->pending_pool); 77492e86812SMikulas Patocka 7751da177e4SLinus Torvalds dm_put_device(ti, s->origin); 776fee1998eSJonathan Brassow 777fee1998eSJonathan Brassow dm_exception_store_destroy(s->store); 778138728dcSAlasdair G Kergon 7791da177e4SLinus Torvalds kfree(s); 7801da177e4SLinus Torvalds } 7811da177e4SLinus Torvalds 7821da177e4SLinus Torvalds /* 7831da177e4SLinus Torvalds * Flush a list of buffers. 7841da177e4SLinus Torvalds */ 7851da177e4SLinus Torvalds static void flush_bios(struct bio *bio) 7861da177e4SLinus Torvalds { 7871da177e4SLinus Torvalds struct bio *n; 7881da177e4SLinus Torvalds 7891da177e4SLinus Torvalds while (bio) { 7901da177e4SLinus Torvalds n = bio->bi_next; 7911da177e4SLinus Torvalds bio->bi_next = NULL; 7921da177e4SLinus Torvalds generic_make_request(bio); 7931da177e4SLinus Torvalds bio = n; 7941da177e4SLinus Torvalds } 7951da177e4SLinus Torvalds } 7961da177e4SLinus Torvalds 797c4028958SDavid Howells static void flush_queued_bios(struct work_struct *work) 798ca3a931fSAlasdair G Kergon { 799c4028958SDavid Howells struct dm_snapshot *s = 800c4028958SDavid Howells container_of(work, struct dm_snapshot, queued_bios_work); 801ca3a931fSAlasdair G Kergon struct bio *queued_bios; 802ca3a931fSAlasdair G Kergon unsigned long flags; 803ca3a931fSAlasdair G Kergon 804ca3a931fSAlasdair G Kergon spin_lock_irqsave(&s->pe_lock, flags); 805ca3a931fSAlasdair G Kergon queued_bios = bio_list_get(&s->queued_bios); 806ca3a931fSAlasdair G Kergon spin_unlock_irqrestore(&s->pe_lock, flags); 807ca3a931fSAlasdair G Kergon 808ca3a931fSAlasdair G Kergon flush_bios(queued_bios); 809ca3a931fSAlasdair G Kergon } 810ca3a931fSAlasdair G Kergon 8111da177e4SLinus Torvalds /* 8121da177e4SLinus Torvalds * Error a list of buffers. 8131da177e4SLinus Torvalds */ 8141da177e4SLinus Torvalds static void error_bios(struct bio *bio) 8151da177e4SLinus Torvalds { 8161da177e4SLinus Torvalds struct bio *n; 8171da177e4SLinus Torvalds 8181da177e4SLinus Torvalds while (bio) { 8191da177e4SLinus Torvalds n = bio->bi_next; 8201da177e4SLinus Torvalds bio->bi_next = NULL; 8216712ecf8SNeilBrown bio_io_error(bio); 8221da177e4SLinus Torvalds bio = n; 8231da177e4SLinus Torvalds } 8241da177e4SLinus Torvalds } 8251da177e4SLinus Torvalds 826695368acSAlasdair G Kergon static void __invalidate_snapshot(struct dm_snapshot *s, int err) 82776df1c65SAlasdair G Kergon { 82876df1c65SAlasdair G Kergon if (!s->valid) 82976df1c65SAlasdair G Kergon return; 83076df1c65SAlasdair G Kergon 83176df1c65SAlasdair G Kergon if (err == -EIO) 83276df1c65SAlasdair G Kergon DMERR("Invalidating snapshot: Error reading/writing."); 83376df1c65SAlasdair G Kergon else if (err == -ENOMEM) 83476df1c65SAlasdair G Kergon DMERR("Invalidating snapshot: Unable to allocate exception."); 83576df1c65SAlasdair G Kergon 836493df71cSJonathan Brassow if (s->store->type->drop_snapshot) 837493df71cSJonathan Brassow s->store->type->drop_snapshot(s->store); 83876df1c65SAlasdair G Kergon 83976df1c65SAlasdair G Kergon s->valid = 0; 84076df1c65SAlasdair G Kergon 8410cea9c78SJonathan Brassow dm_table_event(s->store->ti->table); 84276df1c65SAlasdair G Kergon } 84376df1c65SAlasdair G Kergon 844028867acSAlasdair G Kergon static void get_pending_exception(struct dm_snap_pending_exception *pe) 8454b832e8dSAlasdair G Kergon { 8464b832e8dSAlasdair G Kergon atomic_inc(&pe->ref_count); 8474b832e8dSAlasdair G Kergon } 8484b832e8dSAlasdair G Kergon 849028867acSAlasdair G Kergon static struct bio *put_pending_exception(struct dm_snap_pending_exception *pe) 8504b832e8dSAlasdair G Kergon { 851028867acSAlasdair G Kergon struct dm_snap_pending_exception *primary_pe; 8524b832e8dSAlasdair G Kergon struct bio *origin_bios = NULL; 8534b832e8dSAlasdair G Kergon 8544b832e8dSAlasdair G Kergon primary_pe = pe->primary_pe; 8554b832e8dSAlasdair G Kergon 8564b832e8dSAlasdair G Kergon /* 8574b832e8dSAlasdair G Kergon * If this pe is involved in a write to the origin and 8584b832e8dSAlasdair G Kergon * it is the last sibling to complete then release 8594b832e8dSAlasdair G Kergon * the bios for the original write to the origin. 8604b832e8dSAlasdair G Kergon */ 8614b832e8dSAlasdair G Kergon if (primary_pe && 8627c5f78b9SMikulas Patocka atomic_dec_and_test(&primary_pe->ref_count)) { 8634b832e8dSAlasdair G Kergon origin_bios = bio_list_get(&primary_pe->origin_bios); 8647c5f78b9SMikulas Patocka free_pending_exception(primary_pe); 8657c5f78b9SMikulas Patocka } 8664b832e8dSAlasdair G Kergon 8674b832e8dSAlasdair G Kergon /* 8684b832e8dSAlasdair G Kergon * Free the pe if it's not linked to an origin write or if 8694b832e8dSAlasdair G Kergon * it's not itself a primary pe. 8704b832e8dSAlasdair G Kergon */ 8714b832e8dSAlasdair G Kergon if (!primary_pe || primary_pe != pe) 8724b832e8dSAlasdair G Kergon free_pending_exception(pe); 8734b832e8dSAlasdair G Kergon 8744b832e8dSAlasdair G Kergon return origin_bios; 8754b832e8dSAlasdair G Kergon } 8764b832e8dSAlasdair G Kergon 877028867acSAlasdair G Kergon static void pending_complete(struct dm_snap_pending_exception *pe, int success) 8781da177e4SLinus Torvalds { 8791d4989c8SJon Brassow struct dm_exception *e; 8801da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 8819d493fa8SAlasdair G Kergon struct bio *origin_bios = NULL; 8829d493fa8SAlasdair G Kergon struct bio *snapshot_bios = NULL; 8839d493fa8SAlasdair G Kergon int error = 0; 8841da177e4SLinus Torvalds 88576df1c65SAlasdair G Kergon if (!success) { 88676df1c65SAlasdair G Kergon /* Read/write error - snapshot is unusable */ 8871da177e4SLinus Torvalds down_write(&s->lock); 888695368acSAlasdair G Kergon __invalidate_snapshot(s, -EIO); 8899d493fa8SAlasdair G Kergon error = 1; 89076df1c65SAlasdair G Kergon goto out; 89176df1c65SAlasdair G Kergon } 89276df1c65SAlasdair G Kergon 89376df1c65SAlasdair G Kergon e = alloc_exception(); 89476df1c65SAlasdair G Kergon if (!e) { 89576df1c65SAlasdair G Kergon down_write(&s->lock); 896695368acSAlasdair G Kergon __invalidate_snapshot(s, -ENOMEM); 8979d493fa8SAlasdair G Kergon error = 1; 8981da177e4SLinus Torvalds goto out; 8991da177e4SLinus Torvalds } 9001da177e4SLinus Torvalds *e = pe->e; 9011da177e4SLinus Torvalds 9029d493fa8SAlasdair G Kergon down_write(&s->lock); 9039d493fa8SAlasdair G Kergon if (!s->valid) { 9049d493fa8SAlasdair G Kergon free_exception(e); 9059d493fa8SAlasdair G Kergon error = 1; 9069d493fa8SAlasdair G Kergon goto out; 9079d493fa8SAlasdair G Kergon } 9089d493fa8SAlasdair G Kergon 9091da177e4SLinus Torvalds /* 910a8d41b59SMikulas Patocka * Check for conflicting reads. This is extremely improbable, 91190fa1527SMikulas Patocka * so msleep(1) is sufficient and there is no need for a wait queue. 912a8d41b59SMikulas Patocka */ 913a8d41b59SMikulas Patocka while (__chunk_is_tracked(s, pe->e.old_chunk)) 91490fa1527SMikulas Patocka msleep(1); 915a8d41b59SMikulas Patocka 916a8d41b59SMikulas Patocka /* 9171da177e4SLinus Torvalds * Add a proper exception, and remove the 9181da177e4SLinus Torvalds * in-flight exception from the list. 9191da177e4SLinus Torvalds */ 920d32a6ea6SJon Brassow insert_exception(&s->complete, e); 9211da177e4SLinus Torvalds 9221da177e4SLinus Torvalds out: 923695368acSAlasdair G Kergon remove_exception(&pe->e); 9249d493fa8SAlasdair G Kergon snapshot_bios = bio_list_get(&pe->snapshot_bios); 9254b832e8dSAlasdair G Kergon origin_bios = put_pending_exception(pe); 926b4b610f6SAlasdair G Kergon 9279d493fa8SAlasdair G Kergon up_write(&s->lock); 9289d493fa8SAlasdair G Kergon 9299d493fa8SAlasdair G Kergon /* Submit any pending write bios */ 9309d493fa8SAlasdair G Kergon if (error) 9319d493fa8SAlasdair G Kergon error_bios(snapshot_bios); 9329d493fa8SAlasdair G Kergon else 9339d493fa8SAlasdair G Kergon flush_bios(snapshot_bios); 9349d493fa8SAlasdair G Kergon 9359d493fa8SAlasdair G Kergon flush_bios(origin_bios); 9361da177e4SLinus Torvalds } 9371da177e4SLinus Torvalds 9381da177e4SLinus Torvalds static void commit_callback(void *context, int success) 9391da177e4SLinus Torvalds { 940028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = context; 941028867acSAlasdair G Kergon 9421da177e4SLinus Torvalds pending_complete(pe, success); 9431da177e4SLinus Torvalds } 9441da177e4SLinus Torvalds 9451da177e4SLinus Torvalds /* 9461da177e4SLinus Torvalds * Called when the copy I/O has finished. kcopyd actually runs 9471da177e4SLinus Torvalds * this code so don't block. 9481da177e4SLinus Torvalds */ 9494cdc1d1fSAlasdair G Kergon static void copy_callback(int read_err, unsigned long write_err, void *context) 9501da177e4SLinus Torvalds { 951028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = context; 9521da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 9531da177e4SLinus Torvalds 9541da177e4SLinus Torvalds if (read_err || write_err) 9551da177e4SLinus Torvalds pending_complete(pe, 0); 9561da177e4SLinus Torvalds 9571da177e4SLinus Torvalds else 9581da177e4SLinus Torvalds /* Update the metadata if we are persistent */ 959493df71cSJonathan Brassow s->store->type->commit_exception(s->store, &pe->e, 960b2a11465SJonathan Brassow commit_callback, pe); 9611da177e4SLinus Torvalds } 9621da177e4SLinus Torvalds 9631da177e4SLinus Torvalds /* 9641da177e4SLinus Torvalds * Dispatches the copy operation to kcopyd. 9651da177e4SLinus Torvalds */ 966028867acSAlasdair G Kergon static void start_copy(struct dm_snap_pending_exception *pe) 9671da177e4SLinus Torvalds { 9681da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 96922a1ceb1SHeinz Mauelshagen struct dm_io_region src, dest; 9701da177e4SLinus Torvalds struct block_device *bdev = s->origin->bdev; 9711da177e4SLinus Torvalds sector_t dev_size; 9721da177e4SLinus Torvalds 9731da177e4SLinus Torvalds dev_size = get_dev_size(bdev); 9741da177e4SLinus Torvalds 9751da177e4SLinus Torvalds src.bdev = bdev; 97671fab00aSJonathan Brassow src.sector = chunk_to_sector(s->store, pe->e.old_chunk); 977df96eee6SMikulas Patocka src.count = min((sector_t)s->store->chunk_size, dev_size - src.sector); 9781da177e4SLinus Torvalds 97949beb2b8SJonathan Brassow dest.bdev = s->store->cow->bdev; 98071fab00aSJonathan Brassow dest.sector = chunk_to_sector(s->store, pe->e.new_chunk); 9811da177e4SLinus Torvalds dest.count = src.count; 9821da177e4SLinus Torvalds 9831da177e4SLinus Torvalds /* Hand over to kcopyd */ 984eb69aca5SHeinz Mauelshagen dm_kcopyd_copy(s->kcopyd_client, 9851da177e4SLinus Torvalds &src, 1, &dest, 0, copy_callback, pe); 9861da177e4SLinus Torvalds } 9871da177e4SLinus Torvalds 9882913808eSMikulas Patocka static struct dm_snap_pending_exception * 9892913808eSMikulas Patocka __lookup_pending_exception(struct dm_snapshot *s, chunk_t chunk) 9902913808eSMikulas Patocka { 9911d4989c8SJon Brassow struct dm_exception *e = lookup_exception(&s->pending, chunk); 9922913808eSMikulas Patocka 9932913808eSMikulas Patocka if (!e) 9942913808eSMikulas Patocka return NULL; 9952913808eSMikulas Patocka 9962913808eSMikulas Patocka return container_of(e, struct dm_snap_pending_exception, e); 9972913808eSMikulas Patocka } 9982913808eSMikulas Patocka 9991da177e4SLinus Torvalds /* 10001da177e4SLinus Torvalds * Looks to see if this snapshot already has a pending exception 10011da177e4SLinus Torvalds * for this chunk, otherwise it allocates a new one and inserts 10021da177e4SLinus Torvalds * it into the pending table. 10031da177e4SLinus Torvalds * 10041da177e4SLinus Torvalds * NOTE: a write lock must be held on snap->lock before calling 10051da177e4SLinus Torvalds * this. 10061da177e4SLinus Torvalds */ 1007028867acSAlasdair G Kergon static struct dm_snap_pending_exception * 1008c6621392SMikulas Patocka __find_pending_exception(struct dm_snapshot *s, 1009c6621392SMikulas Patocka struct dm_snap_pending_exception *pe, chunk_t chunk) 10101da177e4SLinus Torvalds { 1011c6621392SMikulas Patocka struct dm_snap_pending_exception *pe2; 101276df1c65SAlasdair G Kergon 10132913808eSMikulas Patocka pe2 = __lookup_pending_exception(s, chunk); 10142913808eSMikulas Patocka if (pe2) { 10151da177e4SLinus Torvalds free_pending_exception(pe); 10162913808eSMikulas Patocka return pe2; 101776df1c65SAlasdair G Kergon } 101876df1c65SAlasdair G Kergon 10191da177e4SLinus Torvalds pe->e.old_chunk = chunk; 10201da177e4SLinus Torvalds bio_list_init(&pe->origin_bios); 10211da177e4SLinus Torvalds bio_list_init(&pe->snapshot_bios); 1022b4b610f6SAlasdair G Kergon pe->primary_pe = NULL; 10234b832e8dSAlasdair G Kergon atomic_set(&pe->ref_count, 0); 10241da177e4SLinus Torvalds pe->started = 0; 10251da177e4SLinus Torvalds 1026493df71cSJonathan Brassow if (s->store->type->prepare_exception(s->store, &pe->e)) { 10271da177e4SLinus Torvalds free_pending_exception(pe); 10281da177e4SLinus Torvalds return NULL; 10291da177e4SLinus Torvalds } 10301da177e4SLinus Torvalds 10314b832e8dSAlasdair G Kergon get_pending_exception(pe); 10321da177e4SLinus Torvalds insert_exception(&s->pending, &pe->e); 10331da177e4SLinus Torvalds 10341da177e4SLinus Torvalds return pe; 10351da177e4SLinus Torvalds } 10361da177e4SLinus Torvalds 10371d4989c8SJon Brassow static void remap_exception(struct dm_snapshot *s, struct dm_exception *e, 1038d74f81f8SMilan Broz struct bio *bio, chunk_t chunk) 10391da177e4SLinus Torvalds { 104049beb2b8SJonathan Brassow bio->bi_bdev = s->store->cow->bdev; 104171fab00aSJonathan Brassow bio->bi_sector = chunk_to_sector(s->store, 104271fab00aSJonathan Brassow dm_chunk_number(e->new_chunk) + 1043d74f81f8SMilan Broz (chunk - e->old_chunk)) + 104471fab00aSJonathan Brassow (bio->bi_sector & 104571fab00aSJonathan Brassow s->store->chunk_mask); 10461da177e4SLinus Torvalds } 10471da177e4SLinus Torvalds 10481da177e4SLinus Torvalds static int snapshot_map(struct dm_target *ti, struct bio *bio, 10491da177e4SLinus Torvalds union map_info *map_context) 10501da177e4SLinus Torvalds { 10511d4989c8SJon Brassow struct dm_exception *e; 1052028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 1053d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED; 10541da177e4SLinus Torvalds chunk_t chunk; 1055028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = NULL; 10561da177e4SLinus Torvalds 1057494b3ee7SMikulas Patocka if (unlikely(bio_empty_barrier(bio))) { 1058494b3ee7SMikulas Patocka bio->bi_bdev = s->store->cow->bdev; 1059494b3ee7SMikulas Patocka return DM_MAPIO_REMAPPED; 1060494b3ee7SMikulas Patocka } 1061494b3ee7SMikulas Patocka 106271fab00aSJonathan Brassow chunk = sector_to_chunk(s->store, bio->bi_sector); 10631da177e4SLinus Torvalds 10641da177e4SLinus Torvalds /* Full snapshots are not usable */ 106576df1c65SAlasdair G Kergon /* To get here the table must be live so s->active is always set. */ 10661da177e4SLinus Torvalds if (!s->valid) 1067f6a80ea8SAlasdair G Kergon return -EIO; 10681da177e4SLinus Torvalds 10691da177e4SLinus Torvalds /* FIXME: should only take write lock if we need 10701da177e4SLinus Torvalds * to copy an exception */ 10711da177e4SLinus Torvalds down_write(&s->lock); 10721da177e4SLinus Torvalds 107376df1c65SAlasdair G Kergon if (!s->valid) { 107476df1c65SAlasdair G Kergon r = -EIO; 107576df1c65SAlasdair G Kergon goto out_unlock; 107676df1c65SAlasdair G Kergon } 107776df1c65SAlasdair G Kergon 10781da177e4SLinus Torvalds /* If the block is already remapped - use that, else remap it */ 10791da177e4SLinus Torvalds e = lookup_exception(&s->complete, chunk); 10801da177e4SLinus Torvalds if (e) { 1081d74f81f8SMilan Broz remap_exception(s, e, bio, chunk); 108276df1c65SAlasdair G Kergon goto out_unlock; 108376df1c65SAlasdair G Kergon } 10841da177e4SLinus Torvalds 1085ba40a2aaSAlasdair G Kergon /* 1086ba40a2aaSAlasdair G Kergon * Write to snapshot - higher level takes care of RW/RO 1087ba40a2aaSAlasdair G Kergon * flags so we should only get this if we are 1088ba40a2aaSAlasdair G Kergon * writeable. 1089ba40a2aaSAlasdair G Kergon */ 1090ba40a2aaSAlasdair G Kergon if (bio_rw(bio) == WRITE) { 10912913808eSMikulas Patocka pe = __lookup_pending_exception(s, chunk); 10922913808eSMikulas Patocka if (!pe) { 1093c6621392SMikulas Patocka up_write(&s->lock); 1094c6621392SMikulas Patocka pe = alloc_pending_exception(s); 1095c6621392SMikulas Patocka down_write(&s->lock); 1096c6621392SMikulas Patocka 1097c6621392SMikulas Patocka if (!s->valid) { 1098c6621392SMikulas Patocka free_pending_exception(pe); 1099c6621392SMikulas Patocka r = -EIO; 1100c6621392SMikulas Patocka goto out_unlock; 1101c6621392SMikulas Patocka } 1102c6621392SMikulas Patocka 110335bf659bSMikulas Patocka e = lookup_exception(&s->complete, chunk); 110435bf659bSMikulas Patocka if (e) { 110535bf659bSMikulas Patocka free_pending_exception(pe); 110635bf659bSMikulas Patocka remap_exception(s, e, bio, chunk); 110735bf659bSMikulas Patocka goto out_unlock; 110835bf659bSMikulas Patocka } 110935bf659bSMikulas Patocka 1110c6621392SMikulas Patocka pe = __find_pending_exception(s, pe, chunk); 11111da177e4SLinus Torvalds if (!pe) { 1112695368acSAlasdair G Kergon __invalidate_snapshot(s, -ENOMEM); 11131da177e4SLinus Torvalds r = -EIO; 111476df1c65SAlasdair G Kergon goto out_unlock; 111576df1c65SAlasdair G Kergon } 11162913808eSMikulas Patocka } 111776df1c65SAlasdair G Kergon 1118d74f81f8SMilan Broz remap_exception(s, &pe->e, bio, chunk); 11191da177e4SLinus Torvalds bio_list_add(&pe->snapshot_bios, bio); 11201da177e4SLinus Torvalds 1121d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 1122ba40a2aaSAlasdair G Kergon 11231da177e4SLinus Torvalds if (!pe->started) { 11241da177e4SLinus Torvalds /* this is protected by snap->lock */ 11251da177e4SLinus Torvalds pe->started = 1; 112676df1c65SAlasdair G Kergon up_write(&s->lock); 112776df1c65SAlasdair G Kergon start_copy(pe); 1128ba40a2aaSAlasdair G Kergon goto out; 1129ba40a2aaSAlasdair G Kergon } 1130cd45daffSMikulas Patocka } else { 11311da177e4SLinus Torvalds bio->bi_bdev = s->origin->bdev; 1132cd45daffSMikulas Patocka map_context->ptr = track_chunk(s, chunk); 1133cd45daffSMikulas Patocka } 11341da177e4SLinus Torvalds 1135ba40a2aaSAlasdair G Kergon out_unlock: 1136ba40a2aaSAlasdair G Kergon up_write(&s->lock); 1137ba40a2aaSAlasdair G Kergon out: 11381da177e4SLinus Torvalds return r; 11391da177e4SLinus Torvalds } 11401da177e4SLinus Torvalds 1141cd45daffSMikulas Patocka static int snapshot_end_io(struct dm_target *ti, struct bio *bio, 1142cd45daffSMikulas Patocka int error, union map_info *map_context) 1143cd45daffSMikulas Patocka { 1144cd45daffSMikulas Patocka struct dm_snapshot *s = ti->private; 1145cd45daffSMikulas Patocka struct dm_snap_tracked_chunk *c = map_context->ptr; 1146cd45daffSMikulas Patocka 1147cd45daffSMikulas Patocka if (c) 1148cd45daffSMikulas Patocka stop_tracking_chunk(s, c); 1149cd45daffSMikulas Patocka 1150cd45daffSMikulas Patocka return 0; 1151cd45daffSMikulas Patocka } 1152cd45daffSMikulas Patocka 11531da177e4SLinus Torvalds static void snapshot_resume(struct dm_target *ti) 11541da177e4SLinus Torvalds { 1155028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 11561da177e4SLinus Torvalds 1157aa14edebSAlasdair G Kergon down_write(&s->lock); 1158aa14edebSAlasdair G Kergon s->active = 1; 1159aa14edebSAlasdair G Kergon up_write(&s->lock); 11601da177e4SLinus Torvalds } 11611da177e4SLinus Torvalds 11621da177e4SLinus Torvalds static int snapshot_status(struct dm_target *ti, status_type_t type, 11631da177e4SLinus Torvalds char *result, unsigned int maxlen) 11641da177e4SLinus Torvalds { 11652e4a31dfSJonathan Brassow unsigned sz = 0; 1166028867acSAlasdair G Kergon struct dm_snapshot *snap = ti->private; 11671da177e4SLinus Torvalds 11681da177e4SLinus Torvalds switch (type) { 11691da177e4SLinus Torvalds case STATUSTYPE_INFO: 117094e76572SMikulas Patocka 117194e76572SMikulas Patocka down_write(&snap->lock); 117294e76572SMikulas Patocka 11731da177e4SLinus Torvalds if (!snap->valid) 11742e4a31dfSJonathan Brassow DMEMIT("Invalid"); 11751da177e4SLinus Torvalds else { 1176493df71cSJonathan Brassow if (snap->store->type->fraction_full) { 11771da177e4SLinus Torvalds sector_t numerator, denominator; 1178493df71cSJonathan Brassow snap->store->type->fraction_full(snap->store, 11791da177e4SLinus Torvalds &numerator, 11801da177e4SLinus Torvalds &denominator); 11812e4a31dfSJonathan Brassow DMEMIT("%llu/%llu", 11824ee218cdSAndrew Morton (unsigned long long)numerator, 11834ee218cdSAndrew Morton (unsigned long long)denominator); 11841da177e4SLinus Torvalds } 11851da177e4SLinus Torvalds else 11862e4a31dfSJonathan Brassow DMEMIT("Unknown"); 11871da177e4SLinus Torvalds } 118894e76572SMikulas Patocka 118994e76572SMikulas Patocka up_write(&snap->lock); 119094e76572SMikulas Patocka 11911da177e4SLinus Torvalds break; 11921da177e4SLinus Torvalds 11931da177e4SLinus Torvalds case STATUSTYPE_TABLE: 11941da177e4SLinus Torvalds /* 11951da177e4SLinus Torvalds * kdevname returns a static pointer so we need 11961da177e4SLinus Torvalds * to make private copies if the output is to 11971da177e4SLinus Torvalds * make sense. 11981da177e4SLinus Torvalds */ 11992e4a31dfSJonathan Brassow DMEMIT("%s", snap->origin->name); 12001e302a92SJonathan Brassow snap->store->type->status(snap->store, type, result + sz, 12011e302a92SJonathan Brassow maxlen - sz); 12021da177e4SLinus Torvalds break; 12031da177e4SLinus Torvalds } 12041da177e4SLinus Torvalds 12051da177e4SLinus Torvalds return 0; 12061da177e4SLinus Torvalds } 12071da177e4SLinus Torvalds 12088811f46cSMike Snitzer static int snapshot_iterate_devices(struct dm_target *ti, 12098811f46cSMike Snitzer iterate_devices_callout_fn fn, void *data) 12108811f46cSMike Snitzer { 12118811f46cSMike Snitzer struct dm_snapshot *snap = ti->private; 12128811f46cSMike Snitzer 12138811f46cSMike Snitzer return fn(ti, snap->origin, 0, ti->len, data); 12148811f46cSMike Snitzer } 12158811f46cSMike Snitzer 12168811f46cSMike Snitzer 12171da177e4SLinus Torvalds /*----------------------------------------------------------------- 12181da177e4SLinus Torvalds * Origin methods 12191da177e4SLinus Torvalds *---------------------------------------------------------------*/ 12201da177e4SLinus Torvalds static int __origin_write(struct list_head *snapshots, struct bio *bio) 12211da177e4SLinus Torvalds { 1222d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED, first = 0; 12231da177e4SLinus Torvalds struct dm_snapshot *snap; 12241d4989c8SJon Brassow struct dm_exception *e; 1225028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe, *next_pe, *primary_pe = NULL; 12261da177e4SLinus Torvalds chunk_t chunk; 1227eccf0817SAlasdair G Kergon LIST_HEAD(pe_queue); 12281da177e4SLinus Torvalds 12291da177e4SLinus Torvalds /* Do all the snapshots on this origin */ 12301da177e4SLinus Torvalds list_for_each_entry (snap, snapshots, list) { 12311da177e4SLinus Torvalds 123276df1c65SAlasdair G Kergon down_write(&snap->lock); 123376df1c65SAlasdair G Kergon 1234aa14edebSAlasdair G Kergon /* Only deal with valid and active snapshots */ 1235aa14edebSAlasdair G Kergon if (!snap->valid || !snap->active) 123676df1c65SAlasdair G Kergon goto next_snapshot; 12371da177e4SLinus Torvalds 1238d5e404c1SAlasdair G Kergon /* Nothing to do if writing beyond end of snapshot */ 12390cea9c78SJonathan Brassow if (bio->bi_sector >= dm_table_get_size(snap->store->ti->table)) 124076df1c65SAlasdair G Kergon goto next_snapshot; 12411da177e4SLinus Torvalds 12421da177e4SLinus Torvalds /* 12431da177e4SLinus Torvalds * Remember, different snapshots can have 12441da177e4SLinus Torvalds * different chunk sizes. 12451da177e4SLinus Torvalds */ 124671fab00aSJonathan Brassow chunk = sector_to_chunk(snap->store, bio->bi_sector); 12471da177e4SLinus Torvalds 12481da177e4SLinus Torvalds /* 12491da177e4SLinus Torvalds * Check exception table to see if block 12501da177e4SLinus Torvalds * is already remapped in this snapshot 12511da177e4SLinus Torvalds * and trigger an exception if not. 1252b4b610f6SAlasdair G Kergon * 12534b832e8dSAlasdair G Kergon * ref_count is initialised to 1 so pending_complete() 1254b4b610f6SAlasdair G Kergon * won't destroy the primary_pe while we're inside this loop. 12551da177e4SLinus Torvalds */ 12561da177e4SLinus Torvalds e = lookup_exception(&snap->complete, chunk); 125776df1c65SAlasdair G Kergon if (e) 125876df1c65SAlasdair G Kergon goto next_snapshot; 125976df1c65SAlasdair G Kergon 12602913808eSMikulas Patocka pe = __lookup_pending_exception(snap, chunk); 12612913808eSMikulas Patocka if (!pe) { 1262c6621392SMikulas Patocka up_write(&snap->lock); 1263c6621392SMikulas Patocka pe = alloc_pending_exception(snap); 1264c6621392SMikulas Patocka down_write(&snap->lock); 1265c6621392SMikulas Patocka 1266c6621392SMikulas Patocka if (!snap->valid) { 1267c6621392SMikulas Patocka free_pending_exception(pe); 1268c6621392SMikulas Patocka goto next_snapshot; 1269c6621392SMikulas Patocka } 1270c6621392SMikulas Patocka 127135bf659bSMikulas Patocka e = lookup_exception(&snap->complete, chunk); 127235bf659bSMikulas Patocka if (e) { 127335bf659bSMikulas Patocka free_pending_exception(pe); 127435bf659bSMikulas Patocka goto next_snapshot; 127535bf659bSMikulas Patocka } 127635bf659bSMikulas Patocka 1277c6621392SMikulas Patocka pe = __find_pending_exception(snap, pe, chunk); 12781da177e4SLinus Torvalds if (!pe) { 1279695368acSAlasdair G Kergon __invalidate_snapshot(snap, -ENOMEM); 128076df1c65SAlasdair G Kergon goto next_snapshot; 128176df1c65SAlasdair G Kergon } 12822913808eSMikulas Patocka } 12831da177e4SLinus Torvalds 1284b4b610f6SAlasdair G Kergon if (!primary_pe) { 1285b4b610f6SAlasdair G Kergon /* 1286b4b610f6SAlasdair G Kergon * Either every pe here has same 1287b4b610f6SAlasdair G Kergon * primary_pe or none has one yet. 1288b4b610f6SAlasdair G Kergon */ 1289b4b610f6SAlasdair G Kergon if (pe->primary_pe) 1290b4b610f6SAlasdair G Kergon primary_pe = pe->primary_pe; 1291b4b610f6SAlasdair G Kergon else { 1292b4b610f6SAlasdair G Kergon primary_pe = pe; 1293b4b610f6SAlasdair G Kergon first = 1; 1294eccf0817SAlasdair G Kergon } 1295b4b610f6SAlasdair G Kergon 129676df1c65SAlasdair G Kergon bio_list_add(&primary_pe->origin_bios, bio); 129776df1c65SAlasdair G Kergon 1298d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 1299b4b610f6SAlasdair G Kergon } 130076df1c65SAlasdair G Kergon 1301b4b610f6SAlasdair G Kergon if (!pe->primary_pe) { 1302b4b610f6SAlasdair G Kergon pe->primary_pe = primary_pe; 13034b832e8dSAlasdair G Kergon get_pending_exception(primary_pe); 1304b4b610f6SAlasdair G Kergon } 130576df1c65SAlasdair G Kergon 1306eccf0817SAlasdair G Kergon if (!pe->started) { 1307eccf0817SAlasdair G Kergon pe->started = 1; 1308eccf0817SAlasdair G Kergon list_add_tail(&pe->list, &pe_queue); 1309eccf0817SAlasdair G Kergon } 13101da177e4SLinus Torvalds 131176df1c65SAlasdair G Kergon next_snapshot: 13121da177e4SLinus Torvalds up_write(&snap->lock); 13131da177e4SLinus Torvalds } 13141da177e4SLinus Torvalds 1315b4b610f6SAlasdair G Kergon if (!primary_pe) 13164b832e8dSAlasdair G Kergon return r; 1317b4b610f6SAlasdair G Kergon 1318b4b610f6SAlasdair G Kergon /* 1319b4b610f6SAlasdair G Kergon * If this is the first time we're processing this chunk and 13204b832e8dSAlasdair G Kergon * ref_count is now 1 it means all the pending exceptions 1321b4b610f6SAlasdair G Kergon * got completed while we were in the loop above, so it falls to 1322b4b610f6SAlasdair G Kergon * us here to remove the primary_pe and submit any origin_bios. 1323b4b610f6SAlasdair G Kergon */ 1324b4b610f6SAlasdair G Kergon 13254b832e8dSAlasdair G Kergon if (first && atomic_dec_and_test(&primary_pe->ref_count)) { 1326b4b610f6SAlasdair G Kergon flush_bios(bio_list_get(&primary_pe->origin_bios)); 1327b4b610f6SAlasdair G Kergon free_pending_exception(primary_pe); 1328b4b610f6SAlasdair G Kergon /* If we got here, pe_queue is necessarily empty. */ 13294b832e8dSAlasdair G Kergon return r; 1330b4b610f6SAlasdair G Kergon } 1331b4b610f6SAlasdair G Kergon 13321da177e4SLinus Torvalds /* 13331da177e4SLinus Torvalds * Now that we have a complete pe list we can start the copying. 13341da177e4SLinus Torvalds */ 1335eccf0817SAlasdair G Kergon list_for_each_entry_safe(pe, next_pe, &pe_queue, list) 13361da177e4SLinus Torvalds start_copy(pe); 13371da177e4SLinus Torvalds 13381da177e4SLinus Torvalds return r; 13391da177e4SLinus Torvalds } 13401da177e4SLinus Torvalds 13411da177e4SLinus Torvalds /* 13421da177e4SLinus Torvalds * Called on a write from the origin driver. 13431da177e4SLinus Torvalds */ 13441da177e4SLinus Torvalds static int do_origin(struct dm_dev *origin, struct bio *bio) 13451da177e4SLinus Torvalds { 13461da177e4SLinus Torvalds struct origin *o; 1347d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED; 13481da177e4SLinus Torvalds 13491da177e4SLinus Torvalds down_read(&_origins_lock); 13501da177e4SLinus Torvalds o = __lookup_origin(origin->bdev); 13511da177e4SLinus Torvalds if (o) 13521da177e4SLinus Torvalds r = __origin_write(&o->snapshots, bio); 13531da177e4SLinus Torvalds up_read(&_origins_lock); 13541da177e4SLinus Torvalds 13551da177e4SLinus Torvalds return r; 13561da177e4SLinus Torvalds } 13571da177e4SLinus Torvalds 13581da177e4SLinus Torvalds /* 13591da177e4SLinus Torvalds * Origin: maps a linear range of a device, with hooks for snapshotting. 13601da177e4SLinus Torvalds */ 13611da177e4SLinus Torvalds 13621da177e4SLinus Torvalds /* 13631da177e4SLinus Torvalds * Construct an origin mapping: <dev_path> 13641da177e4SLinus Torvalds * The context for an origin is merely a 'struct dm_dev *' 13651da177e4SLinus Torvalds * pointing to the real device. 13661da177e4SLinus Torvalds */ 13671da177e4SLinus Torvalds static int origin_ctr(struct dm_target *ti, unsigned int argc, char **argv) 13681da177e4SLinus Torvalds { 13691da177e4SLinus Torvalds int r; 13701da177e4SLinus Torvalds struct dm_dev *dev; 13711da177e4SLinus Torvalds 13721da177e4SLinus Torvalds if (argc != 1) { 137372d94861SAlasdair G Kergon ti->error = "origin: incorrect number of arguments"; 13741da177e4SLinus Torvalds return -EINVAL; 13751da177e4SLinus Torvalds } 13761da177e4SLinus Torvalds 13771da177e4SLinus Torvalds r = dm_get_device(ti, argv[0], 0, ti->len, 13781da177e4SLinus Torvalds dm_table_get_mode(ti->table), &dev); 13791da177e4SLinus Torvalds if (r) { 13801da177e4SLinus Torvalds ti->error = "Cannot get target device"; 13811da177e4SLinus Torvalds return r; 13821da177e4SLinus Torvalds } 13831da177e4SLinus Torvalds 13841da177e4SLinus Torvalds ti->private = dev; 1385494b3ee7SMikulas Patocka ti->num_flush_requests = 1; 1386494b3ee7SMikulas Patocka 13871da177e4SLinus Torvalds return 0; 13881da177e4SLinus Torvalds } 13891da177e4SLinus Torvalds 13901da177e4SLinus Torvalds static void origin_dtr(struct dm_target *ti) 13911da177e4SLinus Torvalds { 1392028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 13931da177e4SLinus Torvalds dm_put_device(ti, dev); 13941da177e4SLinus Torvalds } 13951da177e4SLinus Torvalds 13961da177e4SLinus Torvalds static int origin_map(struct dm_target *ti, struct bio *bio, 13971da177e4SLinus Torvalds union map_info *map_context) 13981da177e4SLinus Torvalds { 1399028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 14001da177e4SLinus Torvalds bio->bi_bdev = dev->bdev; 14011da177e4SLinus Torvalds 1402494b3ee7SMikulas Patocka if (unlikely(bio_empty_barrier(bio))) 1403494b3ee7SMikulas Patocka return DM_MAPIO_REMAPPED; 1404494b3ee7SMikulas Patocka 14051da177e4SLinus Torvalds /* Only tell snapshots if this is a write */ 1406d2a7ad29SKiyoshi Ueda return (bio_rw(bio) == WRITE) ? do_origin(dev, bio) : DM_MAPIO_REMAPPED; 14071da177e4SLinus Torvalds } 14081da177e4SLinus Torvalds 14091da177e4SLinus Torvalds /* 14101da177e4SLinus Torvalds * Set the target "split_io" field to the minimum of all the snapshots' 14111da177e4SLinus Torvalds * chunk sizes. 14121da177e4SLinus Torvalds */ 14131da177e4SLinus Torvalds static void origin_resume(struct dm_target *ti) 14141da177e4SLinus Torvalds { 1415028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 14161da177e4SLinus Torvalds 14171da177e4SLinus Torvalds down_read(&_origins_lock); 14181da177e4SLinus Torvalds 14197e201b35SMikulas Patocka ti->split_io = __minimum_chunk_size(__lookup_origin(dev->bdev)); 14207e201b35SMikulas Patocka 14217e201b35SMikulas Patocka up_read(&_origins_lock); 14221da177e4SLinus Torvalds } 14231da177e4SLinus Torvalds 14241da177e4SLinus Torvalds static int origin_status(struct dm_target *ti, status_type_t type, char *result, 14251da177e4SLinus Torvalds unsigned int maxlen) 14261da177e4SLinus Torvalds { 1427028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 14281da177e4SLinus Torvalds 14291da177e4SLinus Torvalds switch (type) { 14301da177e4SLinus Torvalds case STATUSTYPE_INFO: 14311da177e4SLinus Torvalds result[0] = '\0'; 14321da177e4SLinus Torvalds break; 14331da177e4SLinus Torvalds 14341da177e4SLinus Torvalds case STATUSTYPE_TABLE: 14351da177e4SLinus Torvalds snprintf(result, maxlen, "%s", dev->name); 14361da177e4SLinus Torvalds break; 14371da177e4SLinus Torvalds } 14381da177e4SLinus Torvalds 14391da177e4SLinus Torvalds return 0; 14401da177e4SLinus Torvalds } 14411da177e4SLinus Torvalds 14428811f46cSMike Snitzer static int origin_iterate_devices(struct dm_target *ti, 14438811f46cSMike Snitzer iterate_devices_callout_fn fn, void *data) 14448811f46cSMike Snitzer { 14458811f46cSMike Snitzer struct dm_dev *dev = ti->private; 14468811f46cSMike Snitzer 14478811f46cSMike Snitzer return fn(ti, dev, 0, ti->len, data); 14488811f46cSMike Snitzer } 14498811f46cSMike Snitzer 14501da177e4SLinus Torvalds static struct target_type origin_target = { 14511da177e4SLinus Torvalds .name = "snapshot-origin", 14528811f46cSMike Snitzer .version = {1, 7, 0}, 14531da177e4SLinus Torvalds .module = THIS_MODULE, 14541da177e4SLinus Torvalds .ctr = origin_ctr, 14551da177e4SLinus Torvalds .dtr = origin_dtr, 14561da177e4SLinus Torvalds .map = origin_map, 14571da177e4SLinus Torvalds .resume = origin_resume, 14581da177e4SLinus Torvalds .status = origin_status, 14598811f46cSMike Snitzer .iterate_devices = origin_iterate_devices, 14601da177e4SLinus Torvalds }; 14611da177e4SLinus Torvalds 14621da177e4SLinus Torvalds static struct target_type snapshot_target = { 14631da177e4SLinus Torvalds .name = "snapshot", 14648811f46cSMike Snitzer .version = {1, 7, 0}, 14651da177e4SLinus Torvalds .module = THIS_MODULE, 14661da177e4SLinus Torvalds .ctr = snapshot_ctr, 14671da177e4SLinus Torvalds .dtr = snapshot_dtr, 14681da177e4SLinus Torvalds .map = snapshot_map, 1469cd45daffSMikulas Patocka .end_io = snapshot_end_io, 14701da177e4SLinus Torvalds .resume = snapshot_resume, 14711da177e4SLinus Torvalds .status = snapshot_status, 14728811f46cSMike Snitzer .iterate_devices = snapshot_iterate_devices, 14731da177e4SLinus Torvalds }; 14741da177e4SLinus Torvalds 14751da177e4SLinus Torvalds static int __init dm_snapshot_init(void) 14761da177e4SLinus Torvalds { 14771da177e4SLinus Torvalds int r; 14781da177e4SLinus Torvalds 14794db6bfe0SAlasdair G Kergon r = dm_exception_store_init(); 14804db6bfe0SAlasdair G Kergon if (r) { 14814db6bfe0SAlasdair G Kergon DMERR("Failed to initialize exception stores"); 14824db6bfe0SAlasdair G Kergon return r; 14834db6bfe0SAlasdair G Kergon } 14844db6bfe0SAlasdair G Kergon 14851da177e4SLinus Torvalds r = dm_register_target(&snapshot_target); 14861da177e4SLinus Torvalds if (r) { 14871da177e4SLinus Torvalds DMERR("snapshot target register failed %d", r); 1488034a186dSJonathan Brassow goto bad_register_snapshot_target; 14891da177e4SLinus Torvalds } 14901da177e4SLinus Torvalds 14911da177e4SLinus Torvalds r = dm_register_target(&origin_target); 14921da177e4SLinus Torvalds if (r < 0) { 149372d94861SAlasdair G Kergon DMERR("Origin target register failed %d", r); 14941da177e4SLinus Torvalds goto bad1; 14951da177e4SLinus Torvalds } 14961da177e4SLinus Torvalds 14971da177e4SLinus Torvalds r = init_origin_hash(); 14981da177e4SLinus Torvalds if (r) { 14991da177e4SLinus Torvalds DMERR("init_origin_hash failed."); 15001da177e4SLinus Torvalds goto bad2; 15011da177e4SLinus Torvalds } 15021da177e4SLinus Torvalds 15031d4989c8SJon Brassow exception_cache = KMEM_CACHE(dm_exception, 0); 15041da177e4SLinus Torvalds if (!exception_cache) { 15051da177e4SLinus Torvalds DMERR("Couldn't create exception cache."); 15061da177e4SLinus Torvalds r = -ENOMEM; 15071da177e4SLinus Torvalds goto bad3; 15081da177e4SLinus Torvalds } 15091da177e4SLinus Torvalds 1510028867acSAlasdair G Kergon pending_cache = KMEM_CACHE(dm_snap_pending_exception, 0); 15111da177e4SLinus Torvalds if (!pending_cache) { 15121da177e4SLinus Torvalds DMERR("Couldn't create pending cache."); 15131da177e4SLinus Torvalds r = -ENOMEM; 15141da177e4SLinus Torvalds goto bad4; 15151da177e4SLinus Torvalds } 15161da177e4SLinus Torvalds 1517cd45daffSMikulas Patocka tracked_chunk_cache = KMEM_CACHE(dm_snap_tracked_chunk, 0); 1518cd45daffSMikulas Patocka if (!tracked_chunk_cache) { 1519cd45daffSMikulas Patocka DMERR("Couldn't create cache to track chunks in use."); 1520cd45daffSMikulas Patocka r = -ENOMEM; 1521cd45daffSMikulas Patocka goto bad5; 1522cd45daffSMikulas Patocka } 1523cd45daffSMikulas Patocka 1524ca3a931fSAlasdair G Kergon ksnapd = create_singlethread_workqueue("ksnapd"); 1525ca3a931fSAlasdair G Kergon if (!ksnapd) { 1526ca3a931fSAlasdair G Kergon DMERR("Failed to create ksnapd workqueue."); 1527ca3a931fSAlasdair G Kergon r = -ENOMEM; 152892e86812SMikulas Patocka goto bad_pending_pool; 1529ca3a931fSAlasdair G Kergon } 1530ca3a931fSAlasdair G Kergon 15311da177e4SLinus Torvalds return 0; 15321da177e4SLinus Torvalds 1533cd45daffSMikulas Patocka bad_pending_pool: 1534cd45daffSMikulas Patocka kmem_cache_destroy(tracked_chunk_cache); 15351da177e4SLinus Torvalds bad5: 15361da177e4SLinus Torvalds kmem_cache_destroy(pending_cache); 15371da177e4SLinus Torvalds bad4: 15381da177e4SLinus Torvalds kmem_cache_destroy(exception_cache); 15391da177e4SLinus Torvalds bad3: 15401da177e4SLinus Torvalds exit_origin_hash(); 15411da177e4SLinus Torvalds bad2: 15421da177e4SLinus Torvalds dm_unregister_target(&origin_target); 15431da177e4SLinus Torvalds bad1: 15441da177e4SLinus Torvalds dm_unregister_target(&snapshot_target); 1545034a186dSJonathan Brassow 1546034a186dSJonathan Brassow bad_register_snapshot_target: 1547034a186dSJonathan Brassow dm_exception_store_exit(); 15481da177e4SLinus Torvalds return r; 15491da177e4SLinus Torvalds } 15501da177e4SLinus Torvalds 15511da177e4SLinus Torvalds static void __exit dm_snapshot_exit(void) 15521da177e4SLinus Torvalds { 1553ca3a931fSAlasdair G Kergon destroy_workqueue(ksnapd); 1554ca3a931fSAlasdair G Kergon 155510d3bd09SMikulas Patocka dm_unregister_target(&snapshot_target); 155610d3bd09SMikulas Patocka dm_unregister_target(&origin_target); 15571da177e4SLinus Torvalds 15581da177e4SLinus Torvalds exit_origin_hash(); 15591da177e4SLinus Torvalds kmem_cache_destroy(pending_cache); 15601da177e4SLinus Torvalds kmem_cache_destroy(exception_cache); 1561cd45daffSMikulas Patocka kmem_cache_destroy(tracked_chunk_cache); 15624db6bfe0SAlasdair G Kergon 15634db6bfe0SAlasdair G Kergon dm_exception_store_exit(); 15641da177e4SLinus Torvalds } 15651da177e4SLinus Torvalds 15661da177e4SLinus Torvalds /* Module hooks */ 15671da177e4SLinus Torvalds module_init(dm_snapshot_init); 15681da177e4SLinus Torvalds module_exit(dm_snapshot_exit); 15691da177e4SLinus Torvalds 15701da177e4SLinus Torvalds MODULE_DESCRIPTION(DM_NAME " snapshot target"); 15711da177e4SLinus Torvalds MODULE_AUTHOR("Joe Thornber"); 15721da177e4SLinus Torvalds MODULE_LICENSE("GPL"); 1573