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 { 119028867acSAlasdair G Kergon struct dm_snap_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; 374028867acSAlasdair G Kergon struct dm_snap_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 393028867acSAlasdair G Kergon static void insert_exception(struct exception_table *eh, 394028867acSAlasdair G Kergon struct dm_snap_exception *e) 3951da177e4SLinus Torvalds { 3961da177e4SLinus Torvalds struct list_head *l = &eh->table[exception_hash(eh, e->old_chunk)]; 3971da177e4SLinus Torvalds list_add(&e->hash_list, l); 3981da177e4SLinus Torvalds } 3991da177e4SLinus Torvalds 400028867acSAlasdair G Kergon static void remove_exception(struct dm_snap_exception *e) 4011da177e4SLinus Torvalds { 4021da177e4SLinus Torvalds list_del(&e->hash_list); 4031da177e4SLinus Torvalds } 4041da177e4SLinus Torvalds 4051da177e4SLinus Torvalds /* 4061da177e4SLinus Torvalds * Return the exception data for a sector, or NULL if not 4071da177e4SLinus Torvalds * remapped. 4081da177e4SLinus Torvalds */ 409028867acSAlasdair G Kergon static struct dm_snap_exception *lookup_exception(struct exception_table *et, 4101da177e4SLinus Torvalds chunk_t chunk) 4111da177e4SLinus Torvalds { 4121da177e4SLinus Torvalds struct list_head *slot; 413028867acSAlasdair G Kergon struct dm_snap_exception *e; 4141da177e4SLinus Torvalds 4151da177e4SLinus Torvalds slot = &et->table[exception_hash(et, chunk)]; 4161da177e4SLinus Torvalds list_for_each_entry (e, slot, hash_list) 417d74f81f8SMilan Broz if (chunk >= e->old_chunk && 418d74f81f8SMilan Broz chunk <= e->old_chunk + dm_consecutive_chunk_count(e)) 4191da177e4SLinus Torvalds return e; 4201da177e4SLinus Torvalds 4211da177e4SLinus Torvalds return NULL; 4221da177e4SLinus Torvalds } 4231da177e4SLinus Torvalds 424028867acSAlasdair G Kergon static struct dm_snap_exception *alloc_exception(void) 4251da177e4SLinus Torvalds { 426028867acSAlasdair G Kergon struct dm_snap_exception *e; 4271da177e4SLinus Torvalds 4281da177e4SLinus Torvalds e = kmem_cache_alloc(exception_cache, GFP_NOIO); 4291da177e4SLinus Torvalds if (!e) 4301da177e4SLinus Torvalds e = kmem_cache_alloc(exception_cache, GFP_ATOMIC); 4311da177e4SLinus Torvalds 4321da177e4SLinus Torvalds return e; 4331da177e4SLinus Torvalds } 4341da177e4SLinus Torvalds 435028867acSAlasdair G Kergon static void free_exception(struct dm_snap_exception *e) 4361da177e4SLinus Torvalds { 4371da177e4SLinus Torvalds kmem_cache_free(exception_cache, e); 4381da177e4SLinus Torvalds } 4391da177e4SLinus Torvalds 44092e86812SMikulas Patocka static struct dm_snap_pending_exception *alloc_pending_exception(struct dm_snapshot *s) 4411da177e4SLinus Torvalds { 44292e86812SMikulas Patocka struct dm_snap_pending_exception *pe = mempool_alloc(s->pending_pool, 44392e86812SMikulas Patocka GFP_NOIO); 44492e86812SMikulas Patocka 445879129d2SMikulas Patocka atomic_inc(&s->pending_exceptions_count); 44692e86812SMikulas Patocka pe->snap = s; 44792e86812SMikulas Patocka 44892e86812SMikulas Patocka return pe; 4491da177e4SLinus Torvalds } 4501da177e4SLinus Torvalds 451028867acSAlasdair G Kergon static void free_pending_exception(struct dm_snap_pending_exception *pe) 4521da177e4SLinus Torvalds { 453879129d2SMikulas Patocka struct dm_snapshot *s = pe->snap; 454879129d2SMikulas Patocka 455879129d2SMikulas Patocka mempool_free(pe, s->pending_pool); 456879129d2SMikulas Patocka smp_mb__before_atomic_dec(); 457879129d2SMikulas Patocka atomic_dec(&s->pending_exceptions_count); 4581da177e4SLinus Torvalds } 4591da177e4SLinus Torvalds 460d74f81f8SMilan Broz static void insert_completed_exception(struct dm_snapshot *s, 461d74f81f8SMilan Broz struct dm_snap_exception *new_e) 462d74f81f8SMilan Broz { 463d74f81f8SMilan Broz struct exception_table *eh = &s->complete; 464d74f81f8SMilan Broz struct list_head *l; 465d74f81f8SMilan Broz struct dm_snap_exception *e = NULL; 466d74f81f8SMilan Broz 467d74f81f8SMilan Broz l = &eh->table[exception_hash(eh, new_e->old_chunk)]; 468d74f81f8SMilan Broz 469d74f81f8SMilan Broz /* Add immediately if this table doesn't support consecutive chunks */ 470d74f81f8SMilan Broz if (!eh->hash_shift) 471d74f81f8SMilan Broz goto out; 472d74f81f8SMilan Broz 473d74f81f8SMilan Broz /* List is ordered by old_chunk */ 474d74f81f8SMilan Broz list_for_each_entry_reverse(e, l, hash_list) { 475d74f81f8SMilan Broz /* Insert after an existing chunk? */ 476d74f81f8SMilan Broz if (new_e->old_chunk == (e->old_chunk + 477d74f81f8SMilan Broz dm_consecutive_chunk_count(e) + 1) && 478d74f81f8SMilan Broz new_e->new_chunk == (dm_chunk_number(e->new_chunk) + 479d74f81f8SMilan Broz dm_consecutive_chunk_count(e) + 1)) { 480d74f81f8SMilan Broz dm_consecutive_chunk_count_inc(e); 481d74f81f8SMilan Broz free_exception(new_e); 482d74f81f8SMilan Broz return; 483d74f81f8SMilan Broz } 484d74f81f8SMilan Broz 485d74f81f8SMilan Broz /* Insert before an existing chunk? */ 486d74f81f8SMilan Broz if (new_e->old_chunk == (e->old_chunk - 1) && 487d74f81f8SMilan Broz new_e->new_chunk == (dm_chunk_number(e->new_chunk) - 1)) { 488d74f81f8SMilan Broz dm_consecutive_chunk_count_inc(e); 489d74f81f8SMilan Broz e->old_chunk--; 490d74f81f8SMilan Broz e->new_chunk--; 491d74f81f8SMilan Broz free_exception(new_e); 492d74f81f8SMilan Broz return; 493d74f81f8SMilan Broz } 494d74f81f8SMilan Broz 495d74f81f8SMilan Broz if (new_e->old_chunk > e->old_chunk) 496d74f81f8SMilan Broz break; 497d74f81f8SMilan Broz } 498d74f81f8SMilan Broz 499d74f81f8SMilan Broz out: 500d74f81f8SMilan Broz list_add(&new_e->hash_list, e ? &e->hash_list : l); 501d74f81f8SMilan Broz } 502d74f81f8SMilan Broz 503a159c1acSJonathan Brassow /* 504a159c1acSJonathan Brassow * Callback used by the exception stores to load exceptions when 505a159c1acSJonathan Brassow * initialising. 506a159c1acSJonathan Brassow */ 507a159c1acSJonathan Brassow static int dm_add_exception(void *context, chunk_t old, chunk_t new) 5081da177e4SLinus Torvalds { 509a159c1acSJonathan Brassow struct dm_snapshot *s = context; 510028867acSAlasdair G Kergon struct dm_snap_exception *e; 5111da177e4SLinus Torvalds 5121da177e4SLinus Torvalds e = alloc_exception(); 5131da177e4SLinus Torvalds if (!e) 5141da177e4SLinus Torvalds return -ENOMEM; 5151da177e4SLinus Torvalds 5161da177e4SLinus Torvalds e->old_chunk = old; 517d74f81f8SMilan Broz 518d74f81f8SMilan Broz /* Consecutive_count is implicitly initialised to zero */ 5191da177e4SLinus Torvalds e->new_chunk = new; 520d74f81f8SMilan Broz 521d74f81f8SMilan Broz insert_completed_exception(s, e); 522d74f81f8SMilan Broz 5231da177e4SLinus Torvalds return 0; 5241da177e4SLinus Torvalds } 5251da177e4SLinus Torvalds 5261da177e4SLinus Torvalds /* 5271da177e4SLinus Torvalds * Hard coded magic. 5281da177e4SLinus Torvalds */ 5291da177e4SLinus Torvalds static int calc_max_buckets(void) 5301da177e4SLinus Torvalds { 5311da177e4SLinus Torvalds /* use a fixed size of 2MB */ 5321da177e4SLinus Torvalds unsigned long mem = 2 * 1024 * 1024; 5331da177e4SLinus Torvalds mem /= sizeof(struct list_head); 5341da177e4SLinus Torvalds 5351da177e4SLinus Torvalds return mem; 5361da177e4SLinus Torvalds } 5371da177e4SLinus Torvalds 5381da177e4SLinus Torvalds /* 5391da177e4SLinus Torvalds * Allocate room for a suitable hash table. 5401da177e4SLinus Torvalds */ 541fee1998eSJonathan Brassow static int init_hash_tables(struct dm_snapshot *s) 5421da177e4SLinus Torvalds { 5431da177e4SLinus Torvalds sector_t hash_size, cow_dev_size, origin_dev_size, max_buckets; 5441da177e4SLinus Torvalds 5451da177e4SLinus Torvalds /* 5461da177e4SLinus Torvalds * Calculate based on the size of the original volume or 5471da177e4SLinus Torvalds * the COW volume... 5481da177e4SLinus Torvalds */ 549fee1998eSJonathan Brassow cow_dev_size = get_dev_size(s->store->cow->bdev); 5501da177e4SLinus Torvalds origin_dev_size = get_dev_size(s->origin->bdev); 5511da177e4SLinus Torvalds max_buckets = calc_max_buckets(); 5521da177e4SLinus Torvalds 553fee1998eSJonathan Brassow hash_size = min(origin_dev_size, cow_dev_size) >> s->store->chunk_shift; 5541da177e4SLinus Torvalds hash_size = min(hash_size, max_buckets); 5551da177e4SLinus Torvalds 5568defd830SRobert P. J. Day hash_size = rounddown_pow_of_two(hash_size); 557d74f81f8SMilan Broz if (init_exception_table(&s->complete, hash_size, 558d74f81f8SMilan Broz DM_CHUNK_CONSECUTIVE_BITS)) 5591da177e4SLinus Torvalds return -ENOMEM; 5601da177e4SLinus Torvalds 5611da177e4SLinus Torvalds /* 5621da177e4SLinus Torvalds * Allocate hash table for in-flight exceptions 5631da177e4SLinus Torvalds * Make this smaller than the real hash table 5641da177e4SLinus Torvalds */ 5651da177e4SLinus Torvalds hash_size >>= 3; 5661da177e4SLinus Torvalds if (hash_size < 64) 5671da177e4SLinus Torvalds hash_size = 64; 5681da177e4SLinus Torvalds 569d74f81f8SMilan Broz if (init_exception_table(&s->pending, hash_size, 0)) { 5701da177e4SLinus Torvalds exit_exception_table(&s->complete, exception_cache); 5711da177e4SLinus Torvalds return -ENOMEM; 5721da177e4SLinus Torvalds } 5731da177e4SLinus Torvalds 5741da177e4SLinus Torvalds return 0; 5751da177e4SLinus Torvalds } 5761da177e4SLinus Torvalds 5771da177e4SLinus Torvalds /* 5781da177e4SLinus Torvalds * Construct a snapshot mapping: <origin_dev> <COW-dev> <p/n> <chunk-size> 5791da177e4SLinus Torvalds */ 5801da177e4SLinus Torvalds static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv) 5811da177e4SLinus Torvalds { 5821da177e4SLinus Torvalds struct dm_snapshot *s; 583cd45daffSMikulas Patocka int i; 5841da177e4SLinus Torvalds int r = -EINVAL; 5851da177e4SLinus Torvalds char *origin_path; 586fee1998eSJonathan Brassow struct dm_exception_store *store; 587fee1998eSJonathan Brassow unsigned args_used; 5881da177e4SLinus Torvalds 5894c7e3bf4SMark McLoughlin if (argc != 4) { 59072d94861SAlasdair G Kergon ti->error = "requires exactly 4 arguments"; 5911da177e4SLinus Torvalds r = -EINVAL; 592fee1998eSJonathan Brassow goto bad_args; 5931da177e4SLinus Torvalds } 5941da177e4SLinus Torvalds 5951da177e4SLinus Torvalds origin_path = argv[0]; 596fee1998eSJonathan Brassow argv++; 597fee1998eSJonathan Brassow argc--; 5981da177e4SLinus Torvalds 599fee1998eSJonathan Brassow r = dm_exception_store_create(ti, argc, argv, &args_used, &store); 600fee1998eSJonathan Brassow if (r) { 601fee1998eSJonathan Brassow ti->error = "Couldn't create exception store"; 6021da177e4SLinus Torvalds r = -EINVAL; 603fee1998eSJonathan Brassow goto bad_args; 6041da177e4SLinus Torvalds } 6051da177e4SLinus Torvalds 606fee1998eSJonathan Brassow argv += args_used; 607fee1998eSJonathan Brassow argc -= args_used; 608fee1998eSJonathan Brassow 6091da177e4SLinus Torvalds s = kmalloc(sizeof(*s), GFP_KERNEL); 610fee1998eSJonathan Brassow if (!s) { 6111da177e4SLinus Torvalds ti->error = "Cannot allocate snapshot context private " 6121da177e4SLinus Torvalds "structure"; 6131da177e4SLinus Torvalds r = -ENOMEM; 614fee1998eSJonathan Brassow goto bad_snap; 6151da177e4SLinus Torvalds } 6161da177e4SLinus Torvalds 6171da177e4SLinus Torvalds r = dm_get_device(ti, origin_path, 0, ti->len, FMODE_READ, &s->origin); 6181da177e4SLinus Torvalds if (r) { 6191da177e4SLinus Torvalds ti->error = "Cannot get origin device"; 620fee1998eSJonathan Brassow goto bad_origin; 6211da177e4SLinus Torvalds } 6221da177e4SLinus Torvalds 623fee1998eSJonathan Brassow s->store = store; 6241da177e4SLinus Torvalds s->valid = 1; 625aa14edebSAlasdair G Kergon s->active = 0; 626879129d2SMikulas Patocka atomic_set(&s->pending_exceptions_count, 0); 6271da177e4SLinus Torvalds init_rwsem(&s->lock); 628ca3a931fSAlasdair G Kergon spin_lock_init(&s->pe_lock); 6291da177e4SLinus Torvalds 6301da177e4SLinus Torvalds /* Allocate hash table for COW data */ 631fee1998eSJonathan Brassow if (init_hash_tables(s)) { 6321da177e4SLinus Torvalds ti->error = "Unable to allocate hash table space"; 6331da177e4SLinus Torvalds r = -ENOMEM; 634fee1998eSJonathan Brassow goto bad_hash_tables; 6351da177e4SLinus Torvalds } 6361da177e4SLinus Torvalds 637eb69aca5SHeinz Mauelshagen r = dm_kcopyd_client_create(SNAPSHOT_PAGES, &s->kcopyd_client); 6381da177e4SLinus Torvalds if (r) { 6391da177e4SLinus Torvalds ti->error = "Could not create kcopyd client"; 640fee1998eSJonathan Brassow goto bad_kcopyd; 6411da177e4SLinus Torvalds } 6421da177e4SLinus Torvalds 64392e86812SMikulas Patocka s->pending_pool = mempool_create_slab_pool(MIN_IOS, pending_cache); 64492e86812SMikulas Patocka if (!s->pending_pool) { 64592e86812SMikulas Patocka ti->error = "Could not allocate mempool for pending exceptions"; 646fee1998eSJonathan Brassow goto bad_pending_pool; 64792e86812SMikulas Patocka } 64892e86812SMikulas Patocka 649cd45daffSMikulas Patocka s->tracked_chunk_pool = mempool_create_slab_pool(MIN_IOS, 650cd45daffSMikulas Patocka tracked_chunk_cache); 651cd45daffSMikulas Patocka if (!s->tracked_chunk_pool) { 652cd45daffSMikulas Patocka ti->error = "Could not allocate tracked_chunk mempool for " 653cd45daffSMikulas Patocka "tracking reads"; 65492e86812SMikulas Patocka goto bad_tracked_chunk_pool; 655cd45daffSMikulas Patocka } 656cd45daffSMikulas Patocka 657cd45daffSMikulas Patocka for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) 658cd45daffSMikulas Patocka INIT_HLIST_HEAD(&s->tracked_chunk_hash[i]); 659cd45daffSMikulas Patocka 660cd45daffSMikulas Patocka spin_lock_init(&s->tracked_chunk_lock); 661cd45daffSMikulas Patocka 662aa14edebSAlasdair G Kergon /* Metadata must only be loaded into one table at once */ 663493df71cSJonathan Brassow r = s->store->type->read_metadata(s->store, dm_add_exception, 664493df71cSJonathan Brassow (void *)s); 6650764147bSMilan Broz if (r < 0) { 666f9cea4f7SMark McLoughlin ti->error = "Failed to read snapshot metadata"; 667cd45daffSMikulas Patocka goto bad_load_and_register; 6680764147bSMilan Broz } else if (r > 0) { 6690764147bSMilan Broz s->valid = 0; 6700764147bSMilan Broz DMWARN("Snapshot is marked invalid."); 671f9cea4f7SMark McLoughlin } 672aa14edebSAlasdair G Kergon 673ca3a931fSAlasdair G Kergon bio_list_init(&s->queued_bios); 674c4028958SDavid Howells INIT_WORK(&s->queued_bios_work, flush_queued_bios); 675ca3a931fSAlasdair G Kergon 6761da177e4SLinus Torvalds /* Add snapshot to the list of snapshots for this origin */ 677aa14edebSAlasdair G Kergon /* Exceptions aren't triggered till snapshot_resume() is called */ 6781da177e4SLinus Torvalds if (register_snapshot(s)) { 6791da177e4SLinus Torvalds r = -EINVAL; 6801da177e4SLinus Torvalds ti->error = "Cannot register snapshot origin"; 681cd45daffSMikulas Patocka goto bad_load_and_register; 6821da177e4SLinus Torvalds } 6831da177e4SLinus Torvalds 6841da177e4SLinus Torvalds ti->private = s; 685d0216849SJonathan Brassow ti->split_io = s->store->chunk_size; 686494b3ee7SMikulas Patocka ti->num_flush_requests = 1; 6871da177e4SLinus Torvalds 6881da177e4SLinus Torvalds return 0; 6891da177e4SLinus Torvalds 690cd45daffSMikulas Patocka bad_load_and_register: 691cd45daffSMikulas Patocka mempool_destroy(s->tracked_chunk_pool); 692cd45daffSMikulas Patocka 69392e86812SMikulas Patocka bad_tracked_chunk_pool: 69492e86812SMikulas Patocka mempool_destroy(s->pending_pool); 69592e86812SMikulas Patocka 696fee1998eSJonathan Brassow bad_pending_pool: 697eb69aca5SHeinz Mauelshagen dm_kcopyd_client_destroy(s->kcopyd_client); 6981da177e4SLinus Torvalds 699fee1998eSJonathan Brassow bad_kcopyd: 7001da177e4SLinus Torvalds exit_exception_table(&s->pending, pending_cache); 7011da177e4SLinus Torvalds exit_exception_table(&s->complete, exception_cache); 7021da177e4SLinus Torvalds 703fee1998eSJonathan Brassow bad_hash_tables: 7041da177e4SLinus Torvalds dm_put_device(ti, s->origin); 7051da177e4SLinus Torvalds 706fee1998eSJonathan Brassow bad_origin: 7071da177e4SLinus Torvalds kfree(s); 7081da177e4SLinus Torvalds 709fee1998eSJonathan Brassow bad_snap: 710fee1998eSJonathan Brassow dm_exception_store_destroy(store); 711fee1998eSJonathan Brassow 712fee1998eSJonathan Brassow bad_args: 7131da177e4SLinus Torvalds return r; 7141da177e4SLinus Torvalds } 7151da177e4SLinus Torvalds 71631c93a0cSMilan Broz static void __free_exceptions(struct dm_snapshot *s) 71731c93a0cSMilan Broz { 718eb69aca5SHeinz Mauelshagen dm_kcopyd_client_destroy(s->kcopyd_client); 71931c93a0cSMilan Broz s->kcopyd_client = NULL; 72031c93a0cSMilan Broz 72131c93a0cSMilan Broz exit_exception_table(&s->pending, pending_cache); 72231c93a0cSMilan Broz exit_exception_table(&s->complete, exception_cache); 72331c93a0cSMilan Broz } 72431c93a0cSMilan Broz 7251da177e4SLinus Torvalds static void snapshot_dtr(struct dm_target *ti) 7261da177e4SLinus Torvalds { 727cd45daffSMikulas Patocka #ifdef CONFIG_DM_DEBUG 728cd45daffSMikulas Patocka int i; 729cd45daffSMikulas Patocka #endif 730028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 7311da177e4SLinus Torvalds 732ca3a931fSAlasdair G Kergon flush_workqueue(ksnapd); 733ca3a931fSAlasdair G Kergon 734138728dcSAlasdair G Kergon /* Prevent further origin writes from using this snapshot. */ 735138728dcSAlasdair G Kergon /* After this returns there can be no new kcopyd jobs. */ 7361da177e4SLinus Torvalds unregister_snapshot(s); 7371da177e4SLinus Torvalds 738879129d2SMikulas Patocka while (atomic_read(&s->pending_exceptions_count)) 73990fa1527SMikulas Patocka msleep(1); 740879129d2SMikulas Patocka /* 741879129d2SMikulas Patocka * Ensure instructions in mempool_destroy aren't reordered 742879129d2SMikulas Patocka * before atomic_read. 743879129d2SMikulas Patocka */ 744879129d2SMikulas Patocka smp_mb(); 745879129d2SMikulas Patocka 746cd45daffSMikulas Patocka #ifdef CONFIG_DM_DEBUG 747cd45daffSMikulas Patocka for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) 748cd45daffSMikulas Patocka BUG_ON(!hlist_empty(&s->tracked_chunk_hash[i])); 749cd45daffSMikulas Patocka #endif 750cd45daffSMikulas Patocka 751cd45daffSMikulas Patocka mempool_destroy(s->tracked_chunk_pool); 752cd45daffSMikulas Patocka 75331c93a0cSMilan Broz __free_exceptions(s); 7541da177e4SLinus Torvalds 75592e86812SMikulas Patocka mempool_destroy(s->pending_pool); 75692e86812SMikulas Patocka 7571da177e4SLinus Torvalds dm_put_device(ti, s->origin); 758fee1998eSJonathan Brassow 759fee1998eSJonathan Brassow dm_exception_store_destroy(s->store); 760138728dcSAlasdair G Kergon 7611da177e4SLinus Torvalds kfree(s); 7621da177e4SLinus Torvalds } 7631da177e4SLinus Torvalds 7641da177e4SLinus Torvalds /* 7651da177e4SLinus Torvalds * Flush a list of buffers. 7661da177e4SLinus Torvalds */ 7671da177e4SLinus Torvalds static void flush_bios(struct bio *bio) 7681da177e4SLinus Torvalds { 7691da177e4SLinus Torvalds struct bio *n; 7701da177e4SLinus Torvalds 7711da177e4SLinus Torvalds while (bio) { 7721da177e4SLinus Torvalds n = bio->bi_next; 7731da177e4SLinus Torvalds bio->bi_next = NULL; 7741da177e4SLinus Torvalds generic_make_request(bio); 7751da177e4SLinus Torvalds bio = n; 7761da177e4SLinus Torvalds } 7771da177e4SLinus Torvalds } 7781da177e4SLinus Torvalds 779c4028958SDavid Howells static void flush_queued_bios(struct work_struct *work) 780ca3a931fSAlasdair G Kergon { 781c4028958SDavid Howells struct dm_snapshot *s = 782c4028958SDavid Howells container_of(work, struct dm_snapshot, queued_bios_work); 783ca3a931fSAlasdair G Kergon struct bio *queued_bios; 784ca3a931fSAlasdair G Kergon unsigned long flags; 785ca3a931fSAlasdair G Kergon 786ca3a931fSAlasdair G Kergon spin_lock_irqsave(&s->pe_lock, flags); 787ca3a931fSAlasdair G Kergon queued_bios = bio_list_get(&s->queued_bios); 788ca3a931fSAlasdair G Kergon spin_unlock_irqrestore(&s->pe_lock, flags); 789ca3a931fSAlasdair G Kergon 790ca3a931fSAlasdair G Kergon flush_bios(queued_bios); 791ca3a931fSAlasdair G Kergon } 792ca3a931fSAlasdair G Kergon 7931da177e4SLinus Torvalds /* 7941da177e4SLinus Torvalds * Error a list of buffers. 7951da177e4SLinus Torvalds */ 7961da177e4SLinus Torvalds static void error_bios(struct bio *bio) 7971da177e4SLinus Torvalds { 7981da177e4SLinus Torvalds struct bio *n; 7991da177e4SLinus Torvalds 8001da177e4SLinus Torvalds while (bio) { 8011da177e4SLinus Torvalds n = bio->bi_next; 8021da177e4SLinus Torvalds bio->bi_next = NULL; 8036712ecf8SNeilBrown bio_io_error(bio); 8041da177e4SLinus Torvalds bio = n; 8051da177e4SLinus Torvalds } 8061da177e4SLinus Torvalds } 8071da177e4SLinus Torvalds 808695368acSAlasdair G Kergon static void __invalidate_snapshot(struct dm_snapshot *s, int err) 80976df1c65SAlasdair G Kergon { 81076df1c65SAlasdair G Kergon if (!s->valid) 81176df1c65SAlasdair G Kergon return; 81276df1c65SAlasdair G Kergon 81376df1c65SAlasdair G Kergon if (err == -EIO) 81476df1c65SAlasdair G Kergon DMERR("Invalidating snapshot: Error reading/writing."); 81576df1c65SAlasdair G Kergon else if (err == -ENOMEM) 81676df1c65SAlasdair G Kergon DMERR("Invalidating snapshot: Unable to allocate exception."); 81776df1c65SAlasdair G Kergon 818493df71cSJonathan Brassow if (s->store->type->drop_snapshot) 819493df71cSJonathan Brassow s->store->type->drop_snapshot(s->store); 82076df1c65SAlasdair G Kergon 82176df1c65SAlasdair G Kergon s->valid = 0; 82276df1c65SAlasdair G Kergon 8230cea9c78SJonathan Brassow dm_table_event(s->store->ti->table); 82476df1c65SAlasdair G Kergon } 82576df1c65SAlasdair G Kergon 826028867acSAlasdair G Kergon static void get_pending_exception(struct dm_snap_pending_exception *pe) 8274b832e8dSAlasdair G Kergon { 8284b832e8dSAlasdair G Kergon atomic_inc(&pe->ref_count); 8294b832e8dSAlasdair G Kergon } 8304b832e8dSAlasdair G Kergon 831028867acSAlasdair G Kergon static struct bio *put_pending_exception(struct dm_snap_pending_exception *pe) 8324b832e8dSAlasdair G Kergon { 833028867acSAlasdair G Kergon struct dm_snap_pending_exception *primary_pe; 8344b832e8dSAlasdair G Kergon struct bio *origin_bios = NULL; 8354b832e8dSAlasdair G Kergon 8364b832e8dSAlasdair G Kergon primary_pe = pe->primary_pe; 8374b832e8dSAlasdair G Kergon 8384b832e8dSAlasdair G Kergon /* 8394b832e8dSAlasdair G Kergon * If this pe is involved in a write to the origin and 8404b832e8dSAlasdair G Kergon * it is the last sibling to complete then release 8414b832e8dSAlasdair G Kergon * the bios for the original write to the origin. 8424b832e8dSAlasdair G Kergon */ 8434b832e8dSAlasdair G Kergon if (primary_pe && 8447c5f78b9SMikulas Patocka atomic_dec_and_test(&primary_pe->ref_count)) { 8454b832e8dSAlasdair G Kergon origin_bios = bio_list_get(&primary_pe->origin_bios); 8467c5f78b9SMikulas Patocka free_pending_exception(primary_pe); 8477c5f78b9SMikulas Patocka } 8484b832e8dSAlasdair G Kergon 8494b832e8dSAlasdair G Kergon /* 8504b832e8dSAlasdair G Kergon * Free the pe if it's not linked to an origin write or if 8514b832e8dSAlasdair G Kergon * it's not itself a primary pe. 8524b832e8dSAlasdair G Kergon */ 8534b832e8dSAlasdair G Kergon if (!primary_pe || primary_pe != pe) 8544b832e8dSAlasdair G Kergon free_pending_exception(pe); 8554b832e8dSAlasdair G Kergon 8564b832e8dSAlasdair G Kergon return origin_bios; 8574b832e8dSAlasdair G Kergon } 8584b832e8dSAlasdair G Kergon 859028867acSAlasdair G Kergon static void pending_complete(struct dm_snap_pending_exception *pe, int success) 8601da177e4SLinus Torvalds { 861028867acSAlasdair G Kergon struct dm_snap_exception *e; 8621da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 8639d493fa8SAlasdair G Kergon struct bio *origin_bios = NULL; 8649d493fa8SAlasdair G Kergon struct bio *snapshot_bios = NULL; 8659d493fa8SAlasdair G Kergon int error = 0; 8661da177e4SLinus Torvalds 86776df1c65SAlasdair G Kergon if (!success) { 86876df1c65SAlasdair G Kergon /* Read/write error - snapshot is unusable */ 8691da177e4SLinus Torvalds down_write(&s->lock); 870695368acSAlasdair G Kergon __invalidate_snapshot(s, -EIO); 8719d493fa8SAlasdair G Kergon error = 1; 87276df1c65SAlasdair G Kergon goto out; 87376df1c65SAlasdair G Kergon } 87476df1c65SAlasdair G Kergon 87576df1c65SAlasdair G Kergon e = alloc_exception(); 87676df1c65SAlasdair G Kergon if (!e) { 87776df1c65SAlasdair G Kergon down_write(&s->lock); 878695368acSAlasdair G Kergon __invalidate_snapshot(s, -ENOMEM); 8799d493fa8SAlasdair G Kergon error = 1; 8801da177e4SLinus Torvalds goto out; 8811da177e4SLinus Torvalds } 8821da177e4SLinus Torvalds *e = pe->e; 8831da177e4SLinus Torvalds 8849d493fa8SAlasdair G Kergon down_write(&s->lock); 8859d493fa8SAlasdair G Kergon if (!s->valid) { 8869d493fa8SAlasdair G Kergon free_exception(e); 8879d493fa8SAlasdair G Kergon error = 1; 8889d493fa8SAlasdair G Kergon goto out; 8899d493fa8SAlasdair G Kergon } 8909d493fa8SAlasdair G Kergon 8911da177e4SLinus Torvalds /* 892a8d41b59SMikulas Patocka * Check for conflicting reads. This is extremely improbable, 89390fa1527SMikulas Patocka * so msleep(1) is sufficient and there is no need for a wait queue. 894a8d41b59SMikulas Patocka */ 895a8d41b59SMikulas Patocka while (__chunk_is_tracked(s, pe->e.old_chunk)) 89690fa1527SMikulas Patocka msleep(1); 897a8d41b59SMikulas Patocka 898a8d41b59SMikulas Patocka /* 8991da177e4SLinus Torvalds * Add a proper exception, and remove the 9001da177e4SLinus Torvalds * in-flight exception from the list. 9011da177e4SLinus Torvalds */ 902d74f81f8SMilan Broz insert_completed_exception(s, e); 9031da177e4SLinus Torvalds 9041da177e4SLinus Torvalds out: 905695368acSAlasdair G Kergon remove_exception(&pe->e); 9069d493fa8SAlasdair G Kergon snapshot_bios = bio_list_get(&pe->snapshot_bios); 9074b832e8dSAlasdair G Kergon origin_bios = put_pending_exception(pe); 908b4b610f6SAlasdair G Kergon 9099d493fa8SAlasdair G Kergon up_write(&s->lock); 9109d493fa8SAlasdair G Kergon 9119d493fa8SAlasdair G Kergon /* Submit any pending write bios */ 9129d493fa8SAlasdair G Kergon if (error) 9139d493fa8SAlasdair G Kergon error_bios(snapshot_bios); 9149d493fa8SAlasdair G Kergon else 9159d493fa8SAlasdair G Kergon flush_bios(snapshot_bios); 9169d493fa8SAlasdair G Kergon 9179d493fa8SAlasdair G Kergon flush_bios(origin_bios); 9181da177e4SLinus Torvalds } 9191da177e4SLinus Torvalds 9201da177e4SLinus Torvalds static void commit_callback(void *context, int success) 9211da177e4SLinus Torvalds { 922028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = context; 923028867acSAlasdair G Kergon 9241da177e4SLinus Torvalds pending_complete(pe, success); 9251da177e4SLinus Torvalds } 9261da177e4SLinus Torvalds 9271da177e4SLinus Torvalds /* 9281da177e4SLinus Torvalds * Called when the copy I/O has finished. kcopyd actually runs 9291da177e4SLinus Torvalds * this code so don't block. 9301da177e4SLinus Torvalds */ 9314cdc1d1fSAlasdair G Kergon static void copy_callback(int read_err, unsigned long write_err, void *context) 9321da177e4SLinus Torvalds { 933028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = context; 9341da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 9351da177e4SLinus Torvalds 9361da177e4SLinus Torvalds if (read_err || write_err) 9371da177e4SLinus Torvalds pending_complete(pe, 0); 9381da177e4SLinus Torvalds 9391da177e4SLinus Torvalds else 9401da177e4SLinus Torvalds /* Update the metadata if we are persistent */ 941493df71cSJonathan Brassow s->store->type->commit_exception(s->store, &pe->e, 942b2a11465SJonathan Brassow commit_callback, pe); 9431da177e4SLinus Torvalds } 9441da177e4SLinus Torvalds 9451da177e4SLinus Torvalds /* 9461da177e4SLinus Torvalds * Dispatches the copy operation to kcopyd. 9471da177e4SLinus Torvalds */ 948028867acSAlasdair G Kergon static void start_copy(struct dm_snap_pending_exception *pe) 9491da177e4SLinus Torvalds { 9501da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 95122a1ceb1SHeinz Mauelshagen struct dm_io_region src, dest; 9521da177e4SLinus Torvalds struct block_device *bdev = s->origin->bdev; 9531da177e4SLinus Torvalds sector_t dev_size; 9541da177e4SLinus Torvalds 9551da177e4SLinus Torvalds dev_size = get_dev_size(bdev); 9561da177e4SLinus Torvalds 9571da177e4SLinus Torvalds src.bdev = bdev; 95871fab00aSJonathan Brassow src.sector = chunk_to_sector(s->store, pe->e.old_chunk); 959d0216849SJonathan Brassow src.count = min(s->store->chunk_size, dev_size - src.sector); 9601da177e4SLinus Torvalds 96149beb2b8SJonathan Brassow dest.bdev = s->store->cow->bdev; 96271fab00aSJonathan Brassow dest.sector = chunk_to_sector(s->store, pe->e.new_chunk); 9631da177e4SLinus Torvalds dest.count = src.count; 9641da177e4SLinus Torvalds 9651da177e4SLinus Torvalds /* Hand over to kcopyd */ 966eb69aca5SHeinz Mauelshagen dm_kcopyd_copy(s->kcopyd_client, 9671da177e4SLinus Torvalds &src, 1, &dest, 0, copy_callback, pe); 9681da177e4SLinus Torvalds } 9691da177e4SLinus Torvalds 9702913808eSMikulas Patocka static struct dm_snap_pending_exception * 9712913808eSMikulas Patocka __lookup_pending_exception(struct dm_snapshot *s, chunk_t chunk) 9722913808eSMikulas Patocka { 9732913808eSMikulas Patocka struct dm_snap_exception *e = lookup_exception(&s->pending, chunk); 9742913808eSMikulas Patocka 9752913808eSMikulas Patocka if (!e) 9762913808eSMikulas Patocka return NULL; 9772913808eSMikulas Patocka 9782913808eSMikulas Patocka return container_of(e, struct dm_snap_pending_exception, e); 9792913808eSMikulas Patocka } 9802913808eSMikulas Patocka 9811da177e4SLinus Torvalds /* 9821da177e4SLinus Torvalds * Looks to see if this snapshot already has a pending exception 9831da177e4SLinus Torvalds * for this chunk, otherwise it allocates a new one and inserts 9841da177e4SLinus Torvalds * it into the pending table. 9851da177e4SLinus Torvalds * 9861da177e4SLinus Torvalds * NOTE: a write lock must be held on snap->lock before calling 9871da177e4SLinus Torvalds * this. 9881da177e4SLinus Torvalds */ 989028867acSAlasdair G Kergon static struct dm_snap_pending_exception * 990c6621392SMikulas Patocka __find_pending_exception(struct dm_snapshot *s, 991c6621392SMikulas Patocka struct dm_snap_pending_exception *pe, chunk_t chunk) 9921da177e4SLinus Torvalds { 993c6621392SMikulas Patocka struct dm_snap_pending_exception *pe2; 99476df1c65SAlasdair G Kergon 9952913808eSMikulas Patocka pe2 = __lookup_pending_exception(s, chunk); 9962913808eSMikulas Patocka if (pe2) { 9971da177e4SLinus Torvalds free_pending_exception(pe); 9982913808eSMikulas Patocka return pe2; 99976df1c65SAlasdair G Kergon } 100076df1c65SAlasdair G Kergon 10011da177e4SLinus Torvalds pe->e.old_chunk = chunk; 10021da177e4SLinus Torvalds bio_list_init(&pe->origin_bios); 10031da177e4SLinus Torvalds bio_list_init(&pe->snapshot_bios); 1004b4b610f6SAlasdair G Kergon pe->primary_pe = NULL; 10054b832e8dSAlasdair G Kergon atomic_set(&pe->ref_count, 0); 10061da177e4SLinus Torvalds pe->started = 0; 10071da177e4SLinus Torvalds 1008493df71cSJonathan Brassow if (s->store->type->prepare_exception(s->store, &pe->e)) { 10091da177e4SLinus Torvalds free_pending_exception(pe); 10101da177e4SLinus Torvalds return NULL; 10111da177e4SLinus Torvalds } 10121da177e4SLinus Torvalds 10134b832e8dSAlasdair G Kergon get_pending_exception(pe); 10141da177e4SLinus Torvalds insert_exception(&s->pending, &pe->e); 10151da177e4SLinus Torvalds 10161da177e4SLinus Torvalds return pe; 10171da177e4SLinus Torvalds } 10181da177e4SLinus Torvalds 1019028867acSAlasdair G Kergon static void remap_exception(struct dm_snapshot *s, struct dm_snap_exception *e, 1020d74f81f8SMilan Broz struct bio *bio, chunk_t chunk) 10211da177e4SLinus Torvalds { 102249beb2b8SJonathan Brassow bio->bi_bdev = s->store->cow->bdev; 102371fab00aSJonathan Brassow bio->bi_sector = chunk_to_sector(s->store, 102471fab00aSJonathan Brassow dm_chunk_number(e->new_chunk) + 1025d74f81f8SMilan Broz (chunk - e->old_chunk)) + 102671fab00aSJonathan Brassow (bio->bi_sector & 102771fab00aSJonathan Brassow s->store->chunk_mask); 10281da177e4SLinus Torvalds } 10291da177e4SLinus Torvalds 10301da177e4SLinus Torvalds static int snapshot_map(struct dm_target *ti, struct bio *bio, 10311da177e4SLinus Torvalds union map_info *map_context) 10321da177e4SLinus Torvalds { 1033028867acSAlasdair G Kergon struct dm_snap_exception *e; 1034028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 1035d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED; 10361da177e4SLinus Torvalds chunk_t chunk; 1037028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = NULL; 10381da177e4SLinus Torvalds 1039494b3ee7SMikulas Patocka if (unlikely(bio_empty_barrier(bio))) { 1040494b3ee7SMikulas Patocka bio->bi_bdev = s->store->cow->bdev; 1041494b3ee7SMikulas Patocka return DM_MAPIO_REMAPPED; 1042494b3ee7SMikulas Patocka } 1043494b3ee7SMikulas Patocka 104471fab00aSJonathan Brassow chunk = sector_to_chunk(s->store, bio->bi_sector); 10451da177e4SLinus Torvalds 10461da177e4SLinus Torvalds /* Full snapshots are not usable */ 104776df1c65SAlasdair G Kergon /* To get here the table must be live so s->active is always set. */ 10481da177e4SLinus Torvalds if (!s->valid) 1049f6a80ea8SAlasdair G Kergon return -EIO; 10501da177e4SLinus Torvalds 10511da177e4SLinus Torvalds /* FIXME: should only take write lock if we need 10521da177e4SLinus Torvalds * to copy an exception */ 10531da177e4SLinus Torvalds down_write(&s->lock); 10541da177e4SLinus Torvalds 105576df1c65SAlasdair G Kergon if (!s->valid) { 105676df1c65SAlasdair G Kergon r = -EIO; 105776df1c65SAlasdair G Kergon goto out_unlock; 105876df1c65SAlasdair G Kergon } 105976df1c65SAlasdair G Kergon 10601da177e4SLinus Torvalds /* If the block is already remapped - use that, else remap it */ 10611da177e4SLinus Torvalds e = lookup_exception(&s->complete, chunk); 10621da177e4SLinus Torvalds if (e) { 1063d74f81f8SMilan Broz remap_exception(s, e, bio, chunk); 106476df1c65SAlasdair G Kergon goto out_unlock; 106576df1c65SAlasdair G Kergon } 10661da177e4SLinus Torvalds 1067ba40a2aaSAlasdair G Kergon /* 1068ba40a2aaSAlasdair G Kergon * Write to snapshot - higher level takes care of RW/RO 1069ba40a2aaSAlasdair G Kergon * flags so we should only get this if we are 1070ba40a2aaSAlasdair G Kergon * writeable. 1071ba40a2aaSAlasdair G Kergon */ 1072ba40a2aaSAlasdair G Kergon if (bio_rw(bio) == WRITE) { 10732913808eSMikulas Patocka pe = __lookup_pending_exception(s, chunk); 10742913808eSMikulas Patocka if (!pe) { 1075c6621392SMikulas Patocka up_write(&s->lock); 1076c6621392SMikulas Patocka pe = alloc_pending_exception(s); 1077c6621392SMikulas Patocka down_write(&s->lock); 1078c6621392SMikulas Patocka 1079c6621392SMikulas Patocka if (!s->valid) { 1080c6621392SMikulas Patocka free_pending_exception(pe); 1081c6621392SMikulas Patocka r = -EIO; 1082c6621392SMikulas Patocka goto out_unlock; 1083c6621392SMikulas Patocka } 1084c6621392SMikulas Patocka 108535bf659bSMikulas Patocka e = lookup_exception(&s->complete, chunk); 108635bf659bSMikulas Patocka if (e) { 108735bf659bSMikulas Patocka free_pending_exception(pe); 108835bf659bSMikulas Patocka remap_exception(s, e, bio, chunk); 108935bf659bSMikulas Patocka goto out_unlock; 109035bf659bSMikulas Patocka } 109135bf659bSMikulas Patocka 1092c6621392SMikulas Patocka pe = __find_pending_exception(s, pe, chunk); 10931da177e4SLinus Torvalds if (!pe) { 1094695368acSAlasdair G Kergon __invalidate_snapshot(s, -ENOMEM); 10951da177e4SLinus Torvalds r = -EIO; 109676df1c65SAlasdair G Kergon goto out_unlock; 109776df1c65SAlasdair G Kergon } 10982913808eSMikulas Patocka } 109976df1c65SAlasdair G Kergon 1100d74f81f8SMilan Broz remap_exception(s, &pe->e, bio, chunk); 11011da177e4SLinus Torvalds bio_list_add(&pe->snapshot_bios, bio); 11021da177e4SLinus Torvalds 1103d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 1104ba40a2aaSAlasdair G Kergon 11051da177e4SLinus Torvalds if (!pe->started) { 11061da177e4SLinus Torvalds /* this is protected by snap->lock */ 11071da177e4SLinus Torvalds pe->started = 1; 110876df1c65SAlasdair G Kergon up_write(&s->lock); 110976df1c65SAlasdair G Kergon start_copy(pe); 1110ba40a2aaSAlasdair G Kergon goto out; 1111ba40a2aaSAlasdair G Kergon } 1112cd45daffSMikulas Patocka } else { 11131da177e4SLinus Torvalds bio->bi_bdev = s->origin->bdev; 1114cd45daffSMikulas Patocka map_context->ptr = track_chunk(s, chunk); 1115cd45daffSMikulas Patocka } 11161da177e4SLinus Torvalds 1117ba40a2aaSAlasdair G Kergon out_unlock: 1118ba40a2aaSAlasdair G Kergon up_write(&s->lock); 1119ba40a2aaSAlasdair G Kergon out: 11201da177e4SLinus Torvalds return r; 11211da177e4SLinus Torvalds } 11221da177e4SLinus Torvalds 1123cd45daffSMikulas Patocka static int snapshot_end_io(struct dm_target *ti, struct bio *bio, 1124cd45daffSMikulas Patocka int error, union map_info *map_context) 1125cd45daffSMikulas Patocka { 1126cd45daffSMikulas Patocka struct dm_snapshot *s = ti->private; 1127cd45daffSMikulas Patocka struct dm_snap_tracked_chunk *c = map_context->ptr; 1128cd45daffSMikulas Patocka 1129cd45daffSMikulas Patocka if (c) 1130cd45daffSMikulas Patocka stop_tracking_chunk(s, c); 1131cd45daffSMikulas Patocka 1132cd45daffSMikulas Patocka return 0; 1133cd45daffSMikulas Patocka } 1134cd45daffSMikulas Patocka 11351da177e4SLinus Torvalds static void snapshot_resume(struct dm_target *ti) 11361da177e4SLinus Torvalds { 1137028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 11381da177e4SLinus Torvalds 1139aa14edebSAlasdair G Kergon down_write(&s->lock); 1140aa14edebSAlasdair G Kergon s->active = 1; 1141aa14edebSAlasdair G Kergon up_write(&s->lock); 11421da177e4SLinus Torvalds } 11431da177e4SLinus Torvalds 11441da177e4SLinus Torvalds static int snapshot_status(struct dm_target *ti, status_type_t type, 11451da177e4SLinus Torvalds char *result, unsigned int maxlen) 11461da177e4SLinus Torvalds { 11472e4a31dfSJonathan Brassow unsigned sz = 0; 1148028867acSAlasdair G Kergon struct dm_snapshot *snap = ti->private; 11491da177e4SLinus Torvalds 11501da177e4SLinus Torvalds switch (type) { 11511da177e4SLinus Torvalds case STATUSTYPE_INFO: 11521da177e4SLinus Torvalds if (!snap->valid) 11532e4a31dfSJonathan Brassow DMEMIT("Invalid"); 11541da177e4SLinus Torvalds else { 1155493df71cSJonathan Brassow if (snap->store->type->fraction_full) { 11561da177e4SLinus Torvalds sector_t numerator, denominator; 1157493df71cSJonathan Brassow snap->store->type->fraction_full(snap->store, 11581da177e4SLinus Torvalds &numerator, 11591da177e4SLinus Torvalds &denominator); 11602e4a31dfSJonathan Brassow DMEMIT("%llu/%llu", 11614ee218cdSAndrew Morton (unsigned long long)numerator, 11624ee218cdSAndrew Morton (unsigned long long)denominator); 11631da177e4SLinus Torvalds } 11641da177e4SLinus Torvalds else 11652e4a31dfSJonathan Brassow DMEMIT("Unknown"); 11661da177e4SLinus Torvalds } 11671da177e4SLinus Torvalds break; 11681da177e4SLinus Torvalds 11691da177e4SLinus Torvalds case STATUSTYPE_TABLE: 11701da177e4SLinus Torvalds /* 11711da177e4SLinus Torvalds * kdevname returns a static pointer so we need 11721da177e4SLinus Torvalds * to make private copies if the output is to 11731da177e4SLinus Torvalds * make sense. 11741da177e4SLinus Torvalds */ 11752e4a31dfSJonathan Brassow DMEMIT("%s", snap->origin->name); 11761e302a92SJonathan Brassow snap->store->type->status(snap->store, type, result + sz, 11771e302a92SJonathan Brassow maxlen - sz); 11781da177e4SLinus Torvalds break; 11791da177e4SLinus Torvalds } 11801da177e4SLinus Torvalds 11811da177e4SLinus Torvalds return 0; 11821da177e4SLinus Torvalds } 11831da177e4SLinus Torvalds 11848811f46cSMike Snitzer static int snapshot_iterate_devices(struct dm_target *ti, 11858811f46cSMike Snitzer iterate_devices_callout_fn fn, void *data) 11868811f46cSMike Snitzer { 11878811f46cSMike Snitzer struct dm_snapshot *snap = ti->private; 11888811f46cSMike Snitzer 11898811f46cSMike Snitzer return fn(ti, snap->origin, 0, ti->len, data); 11908811f46cSMike Snitzer } 11918811f46cSMike Snitzer 11928811f46cSMike Snitzer 11931da177e4SLinus Torvalds /*----------------------------------------------------------------- 11941da177e4SLinus Torvalds * Origin methods 11951da177e4SLinus Torvalds *---------------------------------------------------------------*/ 11961da177e4SLinus Torvalds static int __origin_write(struct list_head *snapshots, struct bio *bio) 11971da177e4SLinus Torvalds { 1198d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED, first = 0; 11991da177e4SLinus Torvalds struct dm_snapshot *snap; 1200028867acSAlasdair G Kergon struct dm_snap_exception *e; 1201028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe, *next_pe, *primary_pe = NULL; 12021da177e4SLinus Torvalds chunk_t chunk; 1203eccf0817SAlasdair G Kergon LIST_HEAD(pe_queue); 12041da177e4SLinus Torvalds 12051da177e4SLinus Torvalds /* Do all the snapshots on this origin */ 12061da177e4SLinus Torvalds list_for_each_entry (snap, snapshots, list) { 12071da177e4SLinus Torvalds 120876df1c65SAlasdair G Kergon down_write(&snap->lock); 120976df1c65SAlasdair G Kergon 1210aa14edebSAlasdair G Kergon /* Only deal with valid and active snapshots */ 1211aa14edebSAlasdair G Kergon if (!snap->valid || !snap->active) 121276df1c65SAlasdair G Kergon goto next_snapshot; 12131da177e4SLinus Torvalds 1214d5e404c1SAlasdair G Kergon /* Nothing to do if writing beyond end of snapshot */ 12150cea9c78SJonathan Brassow if (bio->bi_sector >= dm_table_get_size(snap->store->ti->table)) 121676df1c65SAlasdair G Kergon goto next_snapshot; 12171da177e4SLinus Torvalds 12181da177e4SLinus Torvalds /* 12191da177e4SLinus Torvalds * Remember, different snapshots can have 12201da177e4SLinus Torvalds * different chunk sizes. 12211da177e4SLinus Torvalds */ 122271fab00aSJonathan Brassow chunk = sector_to_chunk(snap->store, bio->bi_sector); 12231da177e4SLinus Torvalds 12241da177e4SLinus Torvalds /* 12251da177e4SLinus Torvalds * Check exception table to see if block 12261da177e4SLinus Torvalds * is already remapped in this snapshot 12271da177e4SLinus Torvalds * and trigger an exception if not. 1228b4b610f6SAlasdair G Kergon * 12294b832e8dSAlasdair G Kergon * ref_count is initialised to 1 so pending_complete() 1230b4b610f6SAlasdair G Kergon * won't destroy the primary_pe while we're inside this loop. 12311da177e4SLinus Torvalds */ 12321da177e4SLinus Torvalds e = lookup_exception(&snap->complete, chunk); 123376df1c65SAlasdair G Kergon if (e) 123476df1c65SAlasdair G Kergon goto next_snapshot; 123576df1c65SAlasdair G Kergon 12362913808eSMikulas Patocka pe = __lookup_pending_exception(snap, chunk); 12372913808eSMikulas Patocka if (!pe) { 1238c6621392SMikulas Patocka up_write(&snap->lock); 1239c6621392SMikulas Patocka pe = alloc_pending_exception(snap); 1240c6621392SMikulas Patocka down_write(&snap->lock); 1241c6621392SMikulas Patocka 1242c6621392SMikulas Patocka if (!snap->valid) { 1243c6621392SMikulas Patocka free_pending_exception(pe); 1244c6621392SMikulas Patocka goto next_snapshot; 1245c6621392SMikulas Patocka } 1246c6621392SMikulas Patocka 124735bf659bSMikulas Patocka e = lookup_exception(&snap->complete, chunk); 124835bf659bSMikulas Patocka if (e) { 124935bf659bSMikulas Patocka free_pending_exception(pe); 125035bf659bSMikulas Patocka goto next_snapshot; 125135bf659bSMikulas Patocka } 125235bf659bSMikulas Patocka 1253c6621392SMikulas Patocka pe = __find_pending_exception(snap, pe, chunk); 12541da177e4SLinus Torvalds if (!pe) { 1255695368acSAlasdair G Kergon __invalidate_snapshot(snap, -ENOMEM); 125676df1c65SAlasdair G Kergon goto next_snapshot; 125776df1c65SAlasdair G Kergon } 12582913808eSMikulas Patocka } 12591da177e4SLinus Torvalds 1260b4b610f6SAlasdair G Kergon if (!primary_pe) { 1261b4b610f6SAlasdair G Kergon /* 1262b4b610f6SAlasdair G Kergon * Either every pe here has same 1263b4b610f6SAlasdair G Kergon * primary_pe or none has one yet. 1264b4b610f6SAlasdair G Kergon */ 1265b4b610f6SAlasdair G Kergon if (pe->primary_pe) 1266b4b610f6SAlasdair G Kergon primary_pe = pe->primary_pe; 1267b4b610f6SAlasdair G Kergon else { 1268b4b610f6SAlasdair G Kergon primary_pe = pe; 1269b4b610f6SAlasdair G Kergon first = 1; 1270eccf0817SAlasdair G Kergon } 1271b4b610f6SAlasdair G Kergon 127276df1c65SAlasdair G Kergon bio_list_add(&primary_pe->origin_bios, bio); 127376df1c65SAlasdair G Kergon 1274d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 1275b4b610f6SAlasdair G Kergon } 127676df1c65SAlasdair G Kergon 1277b4b610f6SAlasdair G Kergon if (!pe->primary_pe) { 1278b4b610f6SAlasdair G Kergon pe->primary_pe = primary_pe; 12794b832e8dSAlasdair G Kergon get_pending_exception(primary_pe); 1280b4b610f6SAlasdair G Kergon } 128176df1c65SAlasdair G Kergon 1282eccf0817SAlasdair G Kergon if (!pe->started) { 1283eccf0817SAlasdair G Kergon pe->started = 1; 1284eccf0817SAlasdair G Kergon list_add_tail(&pe->list, &pe_queue); 1285eccf0817SAlasdair G Kergon } 12861da177e4SLinus Torvalds 128776df1c65SAlasdair G Kergon next_snapshot: 12881da177e4SLinus Torvalds up_write(&snap->lock); 12891da177e4SLinus Torvalds } 12901da177e4SLinus Torvalds 1291b4b610f6SAlasdair G Kergon if (!primary_pe) 12924b832e8dSAlasdair G Kergon return r; 1293b4b610f6SAlasdair G Kergon 1294b4b610f6SAlasdair G Kergon /* 1295b4b610f6SAlasdair G Kergon * If this is the first time we're processing this chunk and 12964b832e8dSAlasdair G Kergon * ref_count is now 1 it means all the pending exceptions 1297b4b610f6SAlasdair G Kergon * got completed while we were in the loop above, so it falls to 1298b4b610f6SAlasdair G Kergon * us here to remove the primary_pe and submit any origin_bios. 1299b4b610f6SAlasdair G Kergon */ 1300b4b610f6SAlasdair G Kergon 13014b832e8dSAlasdair G Kergon if (first && atomic_dec_and_test(&primary_pe->ref_count)) { 1302b4b610f6SAlasdair G Kergon flush_bios(bio_list_get(&primary_pe->origin_bios)); 1303b4b610f6SAlasdair G Kergon free_pending_exception(primary_pe); 1304b4b610f6SAlasdair G Kergon /* If we got here, pe_queue is necessarily empty. */ 13054b832e8dSAlasdair G Kergon return r; 1306b4b610f6SAlasdair G Kergon } 1307b4b610f6SAlasdair G Kergon 13081da177e4SLinus Torvalds /* 13091da177e4SLinus Torvalds * Now that we have a complete pe list we can start the copying. 13101da177e4SLinus Torvalds */ 1311eccf0817SAlasdair G Kergon list_for_each_entry_safe(pe, next_pe, &pe_queue, list) 13121da177e4SLinus Torvalds start_copy(pe); 13131da177e4SLinus Torvalds 13141da177e4SLinus Torvalds return r; 13151da177e4SLinus Torvalds } 13161da177e4SLinus Torvalds 13171da177e4SLinus Torvalds /* 13181da177e4SLinus Torvalds * Called on a write from the origin driver. 13191da177e4SLinus Torvalds */ 13201da177e4SLinus Torvalds static int do_origin(struct dm_dev *origin, struct bio *bio) 13211da177e4SLinus Torvalds { 13221da177e4SLinus Torvalds struct origin *o; 1323d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED; 13241da177e4SLinus Torvalds 13251da177e4SLinus Torvalds down_read(&_origins_lock); 13261da177e4SLinus Torvalds o = __lookup_origin(origin->bdev); 13271da177e4SLinus Torvalds if (o) 13281da177e4SLinus Torvalds r = __origin_write(&o->snapshots, bio); 13291da177e4SLinus Torvalds up_read(&_origins_lock); 13301da177e4SLinus Torvalds 13311da177e4SLinus Torvalds return r; 13321da177e4SLinus Torvalds } 13331da177e4SLinus Torvalds 13341da177e4SLinus Torvalds /* 13351da177e4SLinus Torvalds * Origin: maps a linear range of a device, with hooks for snapshotting. 13361da177e4SLinus Torvalds */ 13371da177e4SLinus Torvalds 13381da177e4SLinus Torvalds /* 13391da177e4SLinus Torvalds * Construct an origin mapping: <dev_path> 13401da177e4SLinus Torvalds * The context for an origin is merely a 'struct dm_dev *' 13411da177e4SLinus Torvalds * pointing to the real device. 13421da177e4SLinus Torvalds */ 13431da177e4SLinus Torvalds static int origin_ctr(struct dm_target *ti, unsigned int argc, char **argv) 13441da177e4SLinus Torvalds { 13451da177e4SLinus Torvalds int r; 13461da177e4SLinus Torvalds struct dm_dev *dev; 13471da177e4SLinus Torvalds 13481da177e4SLinus Torvalds if (argc != 1) { 134972d94861SAlasdair G Kergon ti->error = "origin: incorrect number of arguments"; 13501da177e4SLinus Torvalds return -EINVAL; 13511da177e4SLinus Torvalds } 13521da177e4SLinus Torvalds 13531da177e4SLinus Torvalds r = dm_get_device(ti, argv[0], 0, ti->len, 13541da177e4SLinus Torvalds dm_table_get_mode(ti->table), &dev); 13551da177e4SLinus Torvalds if (r) { 13561da177e4SLinus Torvalds ti->error = "Cannot get target device"; 13571da177e4SLinus Torvalds return r; 13581da177e4SLinus Torvalds } 13591da177e4SLinus Torvalds 13601da177e4SLinus Torvalds ti->private = dev; 1361494b3ee7SMikulas Patocka ti->num_flush_requests = 1; 1362494b3ee7SMikulas Patocka 13631da177e4SLinus Torvalds return 0; 13641da177e4SLinus Torvalds } 13651da177e4SLinus Torvalds 13661da177e4SLinus Torvalds static void origin_dtr(struct dm_target *ti) 13671da177e4SLinus Torvalds { 1368028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 13691da177e4SLinus Torvalds dm_put_device(ti, dev); 13701da177e4SLinus Torvalds } 13711da177e4SLinus Torvalds 13721da177e4SLinus Torvalds static int origin_map(struct dm_target *ti, struct bio *bio, 13731da177e4SLinus Torvalds union map_info *map_context) 13741da177e4SLinus Torvalds { 1375028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 13761da177e4SLinus Torvalds bio->bi_bdev = dev->bdev; 13771da177e4SLinus Torvalds 1378494b3ee7SMikulas Patocka if (unlikely(bio_empty_barrier(bio))) 1379494b3ee7SMikulas Patocka return DM_MAPIO_REMAPPED; 1380494b3ee7SMikulas Patocka 13811da177e4SLinus Torvalds /* Only tell snapshots if this is a write */ 1382d2a7ad29SKiyoshi Ueda return (bio_rw(bio) == WRITE) ? do_origin(dev, bio) : DM_MAPIO_REMAPPED; 13831da177e4SLinus Torvalds } 13841da177e4SLinus Torvalds 13851da177e4SLinus Torvalds #define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r)) 13861da177e4SLinus Torvalds 13871da177e4SLinus Torvalds /* 13881da177e4SLinus Torvalds * Set the target "split_io" field to the minimum of all the snapshots' 13891da177e4SLinus Torvalds * chunk sizes. 13901da177e4SLinus Torvalds */ 13911da177e4SLinus Torvalds static void origin_resume(struct dm_target *ti) 13921da177e4SLinus Torvalds { 1393028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 13941da177e4SLinus Torvalds struct dm_snapshot *snap; 13951da177e4SLinus Torvalds struct origin *o; 13961da177e4SLinus Torvalds chunk_t chunk_size = 0; 13971da177e4SLinus Torvalds 13981da177e4SLinus Torvalds down_read(&_origins_lock); 13991da177e4SLinus Torvalds o = __lookup_origin(dev->bdev); 14001da177e4SLinus Torvalds if (o) 14011da177e4SLinus Torvalds list_for_each_entry (snap, &o->snapshots, list) 1402d0216849SJonathan Brassow chunk_size = min_not_zero(chunk_size, 1403d0216849SJonathan Brassow snap->store->chunk_size); 14041da177e4SLinus Torvalds up_read(&_origins_lock); 14051da177e4SLinus Torvalds 14061da177e4SLinus Torvalds ti->split_io = chunk_size; 14071da177e4SLinus Torvalds } 14081da177e4SLinus Torvalds 14091da177e4SLinus Torvalds static int origin_status(struct dm_target *ti, status_type_t type, char *result, 14101da177e4SLinus Torvalds unsigned int maxlen) 14111da177e4SLinus Torvalds { 1412028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 14131da177e4SLinus Torvalds 14141da177e4SLinus Torvalds switch (type) { 14151da177e4SLinus Torvalds case STATUSTYPE_INFO: 14161da177e4SLinus Torvalds result[0] = '\0'; 14171da177e4SLinus Torvalds break; 14181da177e4SLinus Torvalds 14191da177e4SLinus Torvalds case STATUSTYPE_TABLE: 14201da177e4SLinus Torvalds snprintf(result, maxlen, "%s", dev->name); 14211da177e4SLinus Torvalds break; 14221da177e4SLinus Torvalds } 14231da177e4SLinus Torvalds 14241da177e4SLinus Torvalds return 0; 14251da177e4SLinus Torvalds } 14261da177e4SLinus Torvalds 14278811f46cSMike Snitzer static int origin_iterate_devices(struct dm_target *ti, 14288811f46cSMike Snitzer iterate_devices_callout_fn fn, void *data) 14298811f46cSMike Snitzer { 14308811f46cSMike Snitzer struct dm_dev *dev = ti->private; 14318811f46cSMike Snitzer 14328811f46cSMike Snitzer return fn(ti, dev, 0, ti->len, data); 14338811f46cSMike Snitzer } 14348811f46cSMike Snitzer 14351da177e4SLinus Torvalds static struct target_type origin_target = { 14361da177e4SLinus Torvalds .name = "snapshot-origin", 14378811f46cSMike Snitzer .version = {1, 7, 0}, 14381da177e4SLinus Torvalds .module = THIS_MODULE, 14391da177e4SLinus Torvalds .ctr = origin_ctr, 14401da177e4SLinus Torvalds .dtr = origin_dtr, 14411da177e4SLinus Torvalds .map = origin_map, 14421da177e4SLinus Torvalds .resume = origin_resume, 14431da177e4SLinus Torvalds .status = origin_status, 14448811f46cSMike Snitzer .iterate_devices = origin_iterate_devices, 14451da177e4SLinus Torvalds }; 14461da177e4SLinus Torvalds 14471da177e4SLinus Torvalds static struct target_type snapshot_target = { 14481da177e4SLinus Torvalds .name = "snapshot", 14498811f46cSMike Snitzer .version = {1, 7, 0}, 14501da177e4SLinus Torvalds .module = THIS_MODULE, 14511da177e4SLinus Torvalds .ctr = snapshot_ctr, 14521da177e4SLinus Torvalds .dtr = snapshot_dtr, 14531da177e4SLinus Torvalds .map = snapshot_map, 1454cd45daffSMikulas Patocka .end_io = snapshot_end_io, 14551da177e4SLinus Torvalds .resume = snapshot_resume, 14561da177e4SLinus Torvalds .status = snapshot_status, 14578811f46cSMike Snitzer .iterate_devices = snapshot_iterate_devices, 14581da177e4SLinus Torvalds }; 14591da177e4SLinus Torvalds 14601da177e4SLinus Torvalds static int __init dm_snapshot_init(void) 14611da177e4SLinus Torvalds { 14621da177e4SLinus Torvalds int r; 14631da177e4SLinus Torvalds 14644db6bfe0SAlasdair G Kergon r = dm_exception_store_init(); 14654db6bfe0SAlasdair G Kergon if (r) { 14664db6bfe0SAlasdair G Kergon DMERR("Failed to initialize exception stores"); 14674db6bfe0SAlasdair G Kergon return r; 14684db6bfe0SAlasdair G Kergon } 14694db6bfe0SAlasdair G Kergon 14701da177e4SLinus Torvalds r = dm_register_target(&snapshot_target); 14711da177e4SLinus Torvalds if (r) { 14721da177e4SLinus Torvalds DMERR("snapshot target register failed %d", r); 1473034a186dSJonathan Brassow goto bad_register_snapshot_target; 14741da177e4SLinus Torvalds } 14751da177e4SLinus Torvalds 14761da177e4SLinus Torvalds r = dm_register_target(&origin_target); 14771da177e4SLinus Torvalds if (r < 0) { 147872d94861SAlasdair G Kergon DMERR("Origin target register failed %d", r); 14791da177e4SLinus Torvalds goto bad1; 14801da177e4SLinus Torvalds } 14811da177e4SLinus Torvalds 14821da177e4SLinus Torvalds r = init_origin_hash(); 14831da177e4SLinus Torvalds if (r) { 14841da177e4SLinus Torvalds DMERR("init_origin_hash failed."); 14851da177e4SLinus Torvalds goto bad2; 14861da177e4SLinus Torvalds } 14871da177e4SLinus Torvalds 1488028867acSAlasdair G Kergon exception_cache = KMEM_CACHE(dm_snap_exception, 0); 14891da177e4SLinus Torvalds if (!exception_cache) { 14901da177e4SLinus Torvalds DMERR("Couldn't create exception cache."); 14911da177e4SLinus Torvalds r = -ENOMEM; 14921da177e4SLinus Torvalds goto bad3; 14931da177e4SLinus Torvalds } 14941da177e4SLinus Torvalds 1495028867acSAlasdair G Kergon pending_cache = KMEM_CACHE(dm_snap_pending_exception, 0); 14961da177e4SLinus Torvalds if (!pending_cache) { 14971da177e4SLinus Torvalds DMERR("Couldn't create pending cache."); 14981da177e4SLinus Torvalds r = -ENOMEM; 14991da177e4SLinus Torvalds goto bad4; 15001da177e4SLinus Torvalds } 15011da177e4SLinus Torvalds 1502cd45daffSMikulas Patocka tracked_chunk_cache = KMEM_CACHE(dm_snap_tracked_chunk, 0); 1503cd45daffSMikulas Patocka if (!tracked_chunk_cache) { 1504cd45daffSMikulas Patocka DMERR("Couldn't create cache to track chunks in use."); 1505cd45daffSMikulas Patocka r = -ENOMEM; 1506cd45daffSMikulas Patocka goto bad5; 1507cd45daffSMikulas Patocka } 1508cd45daffSMikulas Patocka 1509ca3a931fSAlasdair G Kergon ksnapd = create_singlethread_workqueue("ksnapd"); 1510ca3a931fSAlasdair G Kergon if (!ksnapd) { 1511ca3a931fSAlasdair G Kergon DMERR("Failed to create ksnapd workqueue."); 1512ca3a931fSAlasdair G Kergon r = -ENOMEM; 151392e86812SMikulas Patocka goto bad_pending_pool; 1514ca3a931fSAlasdair G Kergon } 1515ca3a931fSAlasdair G Kergon 15161da177e4SLinus Torvalds return 0; 15171da177e4SLinus Torvalds 1518cd45daffSMikulas Patocka bad_pending_pool: 1519cd45daffSMikulas Patocka kmem_cache_destroy(tracked_chunk_cache); 15201da177e4SLinus Torvalds bad5: 15211da177e4SLinus Torvalds kmem_cache_destroy(pending_cache); 15221da177e4SLinus Torvalds bad4: 15231da177e4SLinus Torvalds kmem_cache_destroy(exception_cache); 15241da177e4SLinus Torvalds bad3: 15251da177e4SLinus Torvalds exit_origin_hash(); 15261da177e4SLinus Torvalds bad2: 15271da177e4SLinus Torvalds dm_unregister_target(&origin_target); 15281da177e4SLinus Torvalds bad1: 15291da177e4SLinus Torvalds dm_unregister_target(&snapshot_target); 1530034a186dSJonathan Brassow 1531034a186dSJonathan Brassow bad_register_snapshot_target: 1532034a186dSJonathan Brassow dm_exception_store_exit(); 15331da177e4SLinus Torvalds return r; 15341da177e4SLinus Torvalds } 15351da177e4SLinus Torvalds 15361da177e4SLinus Torvalds static void __exit dm_snapshot_exit(void) 15371da177e4SLinus Torvalds { 1538ca3a931fSAlasdair G Kergon destroy_workqueue(ksnapd); 1539ca3a931fSAlasdair G Kergon 154010d3bd09SMikulas Patocka dm_unregister_target(&snapshot_target); 154110d3bd09SMikulas Patocka dm_unregister_target(&origin_target); 15421da177e4SLinus Torvalds 15431da177e4SLinus Torvalds exit_origin_hash(); 15441da177e4SLinus Torvalds kmem_cache_destroy(pending_cache); 15451da177e4SLinus Torvalds kmem_cache_destroy(exception_cache); 1546cd45daffSMikulas Patocka kmem_cache_destroy(tracked_chunk_cache); 15474db6bfe0SAlasdair G Kergon 15484db6bfe0SAlasdair G Kergon dm_exception_store_exit(); 15491da177e4SLinus Torvalds } 15501da177e4SLinus Torvalds 15511da177e4SLinus Torvalds /* Module hooks */ 15521da177e4SLinus Torvalds module_init(dm_snapshot_init); 15531da177e4SLinus Torvalds module_exit(dm_snapshot_exit); 15541da177e4SLinus Torvalds 15551da177e4SLinus Torvalds MODULE_DESCRIPTION(DM_NAME " snapshot target"); 15561da177e4SLinus Torvalds MODULE_AUTHOR("Joe Thornber"); 15571da177e4SLinus Torvalds MODULE_LICENSE("GPL"); 1558