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 6763f2412dcSMikulas Patocka if (!s->store->chunk_size) { 6773f2412dcSMikulas Patocka ti->error = "Chunk size not set"; 6783f2412dcSMikulas Patocka goto bad_load_and_register; 6793f2412dcSMikulas Patocka } 6803f2412dcSMikulas Patocka 6811da177e4SLinus Torvalds /* Add snapshot to the list of snapshots for this origin */ 682aa14edebSAlasdair G Kergon /* Exceptions aren't triggered till snapshot_resume() is called */ 6831da177e4SLinus Torvalds if (register_snapshot(s)) { 6841da177e4SLinus Torvalds r = -EINVAL; 6851da177e4SLinus Torvalds ti->error = "Cannot register snapshot origin"; 686cd45daffSMikulas Patocka goto bad_load_and_register; 6871da177e4SLinus Torvalds } 6881da177e4SLinus Torvalds 6891da177e4SLinus Torvalds ti->private = s; 690d0216849SJonathan Brassow ti->split_io = s->store->chunk_size; 691494b3ee7SMikulas Patocka ti->num_flush_requests = 1; 6921da177e4SLinus Torvalds 6931da177e4SLinus Torvalds return 0; 6941da177e4SLinus Torvalds 695cd45daffSMikulas Patocka bad_load_and_register: 696cd45daffSMikulas Patocka mempool_destroy(s->tracked_chunk_pool); 697cd45daffSMikulas Patocka 69892e86812SMikulas Patocka bad_tracked_chunk_pool: 69992e86812SMikulas Patocka mempool_destroy(s->pending_pool); 70092e86812SMikulas Patocka 701fee1998eSJonathan Brassow bad_pending_pool: 702eb69aca5SHeinz Mauelshagen dm_kcopyd_client_destroy(s->kcopyd_client); 7031da177e4SLinus Torvalds 704fee1998eSJonathan Brassow bad_kcopyd: 7051da177e4SLinus Torvalds exit_exception_table(&s->pending, pending_cache); 7061da177e4SLinus Torvalds exit_exception_table(&s->complete, exception_cache); 7071da177e4SLinus Torvalds 708fee1998eSJonathan Brassow bad_hash_tables: 7091da177e4SLinus Torvalds dm_put_device(ti, s->origin); 7101da177e4SLinus Torvalds 711fee1998eSJonathan Brassow bad_origin: 7121da177e4SLinus Torvalds kfree(s); 7131da177e4SLinus Torvalds 714fee1998eSJonathan Brassow bad_snap: 715fee1998eSJonathan Brassow dm_exception_store_destroy(store); 716fee1998eSJonathan Brassow 717fee1998eSJonathan Brassow bad_args: 7181da177e4SLinus Torvalds return r; 7191da177e4SLinus Torvalds } 7201da177e4SLinus Torvalds 72131c93a0cSMilan Broz static void __free_exceptions(struct dm_snapshot *s) 72231c93a0cSMilan Broz { 723eb69aca5SHeinz Mauelshagen dm_kcopyd_client_destroy(s->kcopyd_client); 72431c93a0cSMilan Broz s->kcopyd_client = NULL; 72531c93a0cSMilan Broz 72631c93a0cSMilan Broz exit_exception_table(&s->pending, pending_cache); 72731c93a0cSMilan Broz exit_exception_table(&s->complete, exception_cache); 72831c93a0cSMilan Broz } 72931c93a0cSMilan Broz 7301da177e4SLinus Torvalds static void snapshot_dtr(struct dm_target *ti) 7311da177e4SLinus Torvalds { 732cd45daffSMikulas Patocka #ifdef CONFIG_DM_DEBUG 733cd45daffSMikulas Patocka int i; 734cd45daffSMikulas Patocka #endif 735028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 7361da177e4SLinus Torvalds 737ca3a931fSAlasdair G Kergon flush_workqueue(ksnapd); 738ca3a931fSAlasdair G Kergon 739138728dcSAlasdair G Kergon /* Prevent further origin writes from using this snapshot. */ 740138728dcSAlasdair G Kergon /* After this returns there can be no new kcopyd jobs. */ 7411da177e4SLinus Torvalds unregister_snapshot(s); 7421da177e4SLinus Torvalds 743879129d2SMikulas Patocka while (atomic_read(&s->pending_exceptions_count)) 74490fa1527SMikulas Patocka msleep(1); 745879129d2SMikulas Patocka /* 746879129d2SMikulas Patocka * Ensure instructions in mempool_destroy aren't reordered 747879129d2SMikulas Patocka * before atomic_read. 748879129d2SMikulas Patocka */ 749879129d2SMikulas Patocka smp_mb(); 750879129d2SMikulas Patocka 751cd45daffSMikulas Patocka #ifdef CONFIG_DM_DEBUG 752cd45daffSMikulas Patocka for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) 753cd45daffSMikulas Patocka BUG_ON(!hlist_empty(&s->tracked_chunk_hash[i])); 754cd45daffSMikulas Patocka #endif 755cd45daffSMikulas Patocka 756cd45daffSMikulas Patocka mempool_destroy(s->tracked_chunk_pool); 757cd45daffSMikulas Patocka 75831c93a0cSMilan Broz __free_exceptions(s); 7591da177e4SLinus Torvalds 76092e86812SMikulas Patocka mempool_destroy(s->pending_pool); 76192e86812SMikulas Patocka 7621da177e4SLinus Torvalds dm_put_device(ti, s->origin); 763fee1998eSJonathan Brassow 764fee1998eSJonathan Brassow dm_exception_store_destroy(s->store); 765138728dcSAlasdair G Kergon 7661da177e4SLinus Torvalds kfree(s); 7671da177e4SLinus Torvalds } 7681da177e4SLinus Torvalds 7691da177e4SLinus Torvalds /* 7701da177e4SLinus Torvalds * Flush a list of buffers. 7711da177e4SLinus Torvalds */ 7721da177e4SLinus Torvalds static void flush_bios(struct bio *bio) 7731da177e4SLinus Torvalds { 7741da177e4SLinus Torvalds struct bio *n; 7751da177e4SLinus Torvalds 7761da177e4SLinus Torvalds while (bio) { 7771da177e4SLinus Torvalds n = bio->bi_next; 7781da177e4SLinus Torvalds bio->bi_next = NULL; 7791da177e4SLinus Torvalds generic_make_request(bio); 7801da177e4SLinus Torvalds bio = n; 7811da177e4SLinus Torvalds } 7821da177e4SLinus Torvalds } 7831da177e4SLinus Torvalds 784c4028958SDavid Howells static void flush_queued_bios(struct work_struct *work) 785ca3a931fSAlasdair G Kergon { 786c4028958SDavid Howells struct dm_snapshot *s = 787c4028958SDavid Howells container_of(work, struct dm_snapshot, queued_bios_work); 788ca3a931fSAlasdair G Kergon struct bio *queued_bios; 789ca3a931fSAlasdair G Kergon unsigned long flags; 790ca3a931fSAlasdair G Kergon 791ca3a931fSAlasdair G Kergon spin_lock_irqsave(&s->pe_lock, flags); 792ca3a931fSAlasdair G Kergon queued_bios = bio_list_get(&s->queued_bios); 793ca3a931fSAlasdair G Kergon spin_unlock_irqrestore(&s->pe_lock, flags); 794ca3a931fSAlasdair G Kergon 795ca3a931fSAlasdair G Kergon flush_bios(queued_bios); 796ca3a931fSAlasdair G Kergon } 797ca3a931fSAlasdair G Kergon 7981da177e4SLinus Torvalds /* 7991da177e4SLinus Torvalds * Error a list of buffers. 8001da177e4SLinus Torvalds */ 8011da177e4SLinus Torvalds static void error_bios(struct bio *bio) 8021da177e4SLinus Torvalds { 8031da177e4SLinus Torvalds struct bio *n; 8041da177e4SLinus Torvalds 8051da177e4SLinus Torvalds while (bio) { 8061da177e4SLinus Torvalds n = bio->bi_next; 8071da177e4SLinus Torvalds bio->bi_next = NULL; 8086712ecf8SNeilBrown bio_io_error(bio); 8091da177e4SLinus Torvalds bio = n; 8101da177e4SLinus Torvalds } 8111da177e4SLinus Torvalds } 8121da177e4SLinus Torvalds 813695368acSAlasdair G Kergon static void __invalidate_snapshot(struct dm_snapshot *s, int err) 81476df1c65SAlasdair G Kergon { 81576df1c65SAlasdair G Kergon if (!s->valid) 81676df1c65SAlasdair G Kergon return; 81776df1c65SAlasdair G Kergon 81876df1c65SAlasdair G Kergon if (err == -EIO) 81976df1c65SAlasdair G Kergon DMERR("Invalidating snapshot: Error reading/writing."); 82076df1c65SAlasdair G Kergon else if (err == -ENOMEM) 82176df1c65SAlasdair G Kergon DMERR("Invalidating snapshot: Unable to allocate exception."); 82276df1c65SAlasdair G Kergon 823493df71cSJonathan Brassow if (s->store->type->drop_snapshot) 824493df71cSJonathan Brassow s->store->type->drop_snapshot(s->store); 82576df1c65SAlasdair G Kergon 82676df1c65SAlasdair G Kergon s->valid = 0; 82776df1c65SAlasdair G Kergon 8280cea9c78SJonathan Brassow dm_table_event(s->store->ti->table); 82976df1c65SAlasdair G Kergon } 83076df1c65SAlasdair G Kergon 831028867acSAlasdair G Kergon static void get_pending_exception(struct dm_snap_pending_exception *pe) 8324b832e8dSAlasdair G Kergon { 8334b832e8dSAlasdair G Kergon atomic_inc(&pe->ref_count); 8344b832e8dSAlasdair G Kergon } 8354b832e8dSAlasdair G Kergon 836028867acSAlasdair G Kergon static struct bio *put_pending_exception(struct dm_snap_pending_exception *pe) 8374b832e8dSAlasdair G Kergon { 838028867acSAlasdair G Kergon struct dm_snap_pending_exception *primary_pe; 8394b832e8dSAlasdair G Kergon struct bio *origin_bios = NULL; 8404b832e8dSAlasdair G Kergon 8414b832e8dSAlasdair G Kergon primary_pe = pe->primary_pe; 8424b832e8dSAlasdair G Kergon 8434b832e8dSAlasdair G Kergon /* 8444b832e8dSAlasdair G Kergon * If this pe is involved in a write to the origin and 8454b832e8dSAlasdair G Kergon * it is the last sibling to complete then release 8464b832e8dSAlasdair G Kergon * the bios for the original write to the origin. 8474b832e8dSAlasdair G Kergon */ 8484b832e8dSAlasdair G Kergon if (primary_pe && 8497c5f78b9SMikulas Patocka atomic_dec_and_test(&primary_pe->ref_count)) { 8504b832e8dSAlasdair G Kergon origin_bios = bio_list_get(&primary_pe->origin_bios); 8517c5f78b9SMikulas Patocka free_pending_exception(primary_pe); 8527c5f78b9SMikulas Patocka } 8534b832e8dSAlasdair G Kergon 8544b832e8dSAlasdair G Kergon /* 8554b832e8dSAlasdair G Kergon * Free the pe if it's not linked to an origin write or if 8564b832e8dSAlasdair G Kergon * it's not itself a primary pe. 8574b832e8dSAlasdair G Kergon */ 8584b832e8dSAlasdair G Kergon if (!primary_pe || primary_pe != pe) 8594b832e8dSAlasdair G Kergon free_pending_exception(pe); 8604b832e8dSAlasdair G Kergon 8614b832e8dSAlasdair G Kergon return origin_bios; 8624b832e8dSAlasdair G Kergon } 8634b832e8dSAlasdair G Kergon 864028867acSAlasdair G Kergon static void pending_complete(struct dm_snap_pending_exception *pe, int success) 8651da177e4SLinus Torvalds { 866028867acSAlasdair G Kergon struct dm_snap_exception *e; 8671da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 8689d493fa8SAlasdair G Kergon struct bio *origin_bios = NULL; 8699d493fa8SAlasdair G Kergon struct bio *snapshot_bios = NULL; 8709d493fa8SAlasdair G Kergon int error = 0; 8711da177e4SLinus Torvalds 87276df1c65SAlasdair G Kergon if (!success) { 87376df1c65SAlasdair G Kergon /* Read/write error - snapshot is unusable */ 8741da177e4SLinus Torvalds down_write(&s->lock); 875695368acSAlasdair G Kergon __invalidate_snapshot(s, -EIO); 8769d493fa8SAlasdair G Kergon error = 1; 87776df1c65SAlasdair G Kergon goto out; 87876df1c65SAlasdair G Kergon } 87976df1c65SAlasdair G Kergon 88076df1c65SAlasdair G Kergon e = alloc_exception(); 88176df1c65SAlasdair G Kergon if (!e) { 88276df1c65SAlasdair G Kergon down_write(&s->lock); 883695368acSAlasdair G Kergon __invalidate_snapshot(s, -ENOMEM); 8849d493fa8SAlasdair G Kergon error = 1; 8851da177e4SLinus Torvalds goto out; 8861da177e4SLinus Torvalds } 8871da177e4SLinus Torvalds *e = pe->e; 8881da177e4SLinus Torvalds 8899d493fa8SAlasdair G Kergon down_write(&s->lock); 8909d493fa8SAlasdair G Kergon if (!s->valid) { 8919d493fa8SAlasdair G Kergon free_exception(e); 8929d493fa8SAlasdair G Kergon error = 1; 8939d493fa8SAlasdair G Kergon goto out; 8949d493fa8SAlasdair G Kergon } 8959d493fa8SAlasdair G Kergon 8961da177e4SLinus Torvalds /* 897a8d41b59SMikulas Patocka * Check for conflicting reads. This is extremely improbable, 89890fa1527SMikulas Patocka * so msleep(1) is sufficient and there is no need for a wait queue. 899a8d41b59SMikulas Patocka */ 900a8d41b59SMikulas Patocka while (__chunk_is_tracked(s, pe->e.old_chunk)) 90190fa1527SMikulas Patocka msleep(1); 902a8d41b59SMikulas Patocka 903a8d41b59SMikulas Patocka /* 9041da177e4SLinus Torvalds * Add a proper exception, and remove the 9051da177e4SLinus Torvalds * in-flight exception from the list. 9061da177e4SLinus Torvalds */ 907d74f81f8SMilan Broz insert_completed_exception(s, e); 9081da177e4SLinus Torvalds 9091da177e4SLinus Torvalds out: 910695368acSAlasdair G Kergon remove_exception(&pe->e); 9119d493fa8SAlasdair G Kergon snapshot_bios = bio_list_get(&pe->snapshot_bios); 9124b832e8dSAlasdair G Kergon origin_bios = put_pending_exception(pe); 913b4b610f6SAlasdair G Kergon 9149d493fa8SAlasdair G Kergon up_write(&s->lock); 9159d493fa8SAlasdair G Kergon 9169d493fa8SAlasdair G Kergon /* Submit any pending write bios */ 9179d493fa8SAlasdair G Kergon if (error) 9189d493fa8SAlasdair G Kergon error_bios(snapshot_bios); 9199d493fa8SAlasdair G Kergon else 9209d493fa8SAlasdair G Kergon flush_bios(snapshot_bios); 9219d493fa8SAlasdair G Kergon 9229d493fa8SAlasdair G Kergon flush_bios(origin_bios); 9231da177e4SLinus Torvalds } 9241da177e4SLinus Torvalds 9251da177e4SLinus Torvalds static void commit_callback(void *context, int success) 9261da177e4SLinus Torvalds { 927028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = context; 928028867acSAlasdair G Kergon 9291da177e4SLinus Torvalds pending_complete(pe, success); 9301da177e4SLinus Torvalds } 9311da177e4SLinus Torvalds 9321da177e4SLinus Torvalds /* 9331da177e4SLinus Torvalds * Called when the copy I/O has finished. kcopyd actually runs 9341da177e4SLinus Torvalds * this code so don't block. 9351da177e4SLinus Torvalds */ 9364cdc1d1fSAlasdair G Kergon static void copy_callback(int read_err, unsigned long write_err, void *context) 9371da177e4SLinus Torvalds { 938028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = context; 9391da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 9401da177e4SLinus Torvalds 9411da177e4SLinus Torvalds if (read_err || write_err) 9421da177e4SLinus Torvalds pending_complete(pe, 0); 9431da177e4SLinus Torvalds 9441da177e4SLinus Torvalds else 9451da177e4SLinus Torvalds /* Update the metadata if we are persistent */ 946493df71cSJonathan Brassow s->store->type->commit_exception(s->store, &pe->e, 947b2a11465SJonathan Brassow commit_callback, pe); 9481da177e4SLinus Torvalds } 9491da177e4SLinus Torvalds 9501da177e4SLinus Torvalds /* 9511da177e4SLinus Torvalds * Dispatches the copy operation to kcopyd. 9521da177e4SLinus Torvalds */ 953028867acSAlasdair G Kergon static void start_copy(struct dm_snap_pending_exception *pe) 9541da177e4SLinus Torvalds { 9551da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 95622a1ceb1SHeinz Mauelshagen struct dm_io_region src, dest; 9571da177e4SLinus Torvalds struct block_device *bdev = s->origin->bdev; 9581da177e4SLinus Torvalds sector_t dev_size; 9591da177e4SLinus Torvalds 9601da177e4SLinus Torvalds dev_size = get_dev_size(bdev); 9611da177e4SLinus Torvalds 9621da177e4SLinus Torvalds src.bdev = bdev; 96371fab00aSJonathan Brassow src.sector = chunk_to_sector(s->store, pe->e.old_chunk); 964df96eee6SMikulas Patocka src.count = min((sector_t)s->store->chunk_size, dev_size - src.sector); 9651da177e4SLinus Torvalds 96649beb2b8SJonathan Brassow dest.bdev = s->store->cow->bdev; 96771fab00aSJonathan Brassow dest.sector = chunk_to_sector(s->store, pe->e.new_chunk); 9681da177e4SLinus Torvalds dest.count = src.count; 9691da177e4SLinus Torvalds 9701da177e4SLinus Torvalds /* Hand over to kcopyd */ 971eb69aca5SHeinz Mauelshagen dm_kcopyd_copy(s->kcopyd_client, 9721da177e4SLinus Torvalds &src, 1, &dest, 0, copy_callback, pe); 9731da177e4SLinus Torvalds } 9741da177e4SLinus Torvalds 9752913808eSMikulas Patocka static struct dm_snap_pending_exception * 9762913808eSMikulas Patocka __lookup_pending_exception(struct dm_snapshot *s, chunk_t chunk) 9772913808eSMikulas Patocka { 9782913808eSMikulas Patocka struct dm_snap_exception *e = lookup_exception(&s->pending, chunk); 9792913808eSMikulas Patocka 9802913808eSMikulas Patocka if (!e) 9812913808eSMikulas Patocka return NULL; 9822913808eSMikulas Patocka 9832913808eSMikulas Patocka return container_of(e, struct dm_snap_pending_exception, e); 9842913808eSMikulas Patocka } 9852913808eSMikulas Patocka 9861da177e4SLinus Torvalds /* 9871da177e4SLinus Torvalds * Looks to see if this snapshot already has a pending exception 9881da177e4SLinus Torvalds * for this chunk, otherwise it allocates a new one and inserts 9891da177e4SLinus Torvalds * it into the pending table. 9901da177e4SLinus Torvalds * 9911da177e4SLinus Torvalds * NOTE: a write lock must be held on snap->lock before calling 9921da177e4SLinus Torvalds * this. 9931da177e4SLinus Torvalds */ 994028867acSAlasdair G Kergon static struct dm_snap_pending_exception * 995c6621392SMikulas Patocka __find_pending_exception(struct dm_snapshot *s, 996c6621392SMikulas Patocka struct dm_snap_pending_exception *pe, chunk_t chunk) 9971da177e4SLinus Torvalds { 998c6621392SMikulas Patocka struct dm_snap_pending_exception *pe2; 99976df1c65SAlasdair G Kergon 10002913808eSMikulas Patocka pe2 = __lookup_pending_exception(s, chunk); 10012913808eSMikulas Patocka if (pe2) { 10021da177e4SLinus Torvalds free_pending_exception(pe); 10032913808eSMikulas Patocka return pe2; 100476df1c65SAlasdair G Kergon } 100576df1c65SAlasdair G Kergon 10061da177e4SLinus Torvalds pe->e.old_chunk = chunk; 10071da177e4SLinus Torvalds bio_list_init(&pe->origin_bios); 10081da177e4SLinus Torvalds bio_list_init(&pe->snapshot_bios); 1009b4b610f6SAlasdair G Kergon pe->primary_pe = NULL; 10104b832e8dSAlasdair G Kergon atomic_set(&pe->ref_count, 0); 10111da177e4SLinus Torvalds pe->started = 0; 10121da177e4SLinus Torvalds 1013493df71cSJonathan Brassow if (s->store->type->prepare_exception(s->store, &pe->e)) { 10141da177e4SLinus Torvalds free_pending_exception(pe); 10151da177e4SLinus Torvalds return NULL; 10161da177e4SLinus Torvalds } 10171da177e4SLinus Torvalds 10184b832e8dSAlasdair G Kergon get_pending_exception(pe); 10191da177e4SLinus Torvalds insert_exception(&s->pending, &pe->e); 10201da177e4SLinus Torvalds 10211da177e4SLinus Torvalds return pe; 10221da177e4SLinus Torvalds } 10231da177e4SLinus Torvalds 1024028867acSAlasdair G Kergon static void remap_exception(struct dm_snapshot *s, struct dm_snap_exception *e, 1025d74f81f8SMilan Broz struct bio *bio, chunk_t chunk) 10261da177e4SLinus Torvalds { 102749beb2b8SJonathan Brassow bio->bi_bdev = s->store->cow->bdev; 102871fab00aSJonathan Brassow bio->bi_sector = chunk_to_sector(s->store, 102971fab00aSJonathan Brassow dm_chunk_number(e->new_chunk) + 1030d74f81f8SMilan Broz (chunk - e->old_chunk)) + 103171fab00aSJonathan Brassow (bio->bi_sector & 103271fab00aSJonathan Brassow s->store->chunk_mask); 10331da177e4SLinus Torvalds } 10341da177e4SLinus Torvalds 10351da177e4SLinus Torvalds static int snapshot_map(struct dm_target *ti, struct bio *bio, 10361da177e4SLinus Torvalds union map_info *map_context) 10371da177e4SLinus Torvalds { 1038028867acSAlasdair G Kergon struct dm_snap_exception *e; 1039028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 1040d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED; 10411da177e4SLinus Torvalds chunk_t chunk; 1042028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = NULL; 10431da177e4SLinus Torvalds 1044494b3ee7SMikulas Patocka if (unlikely(bio_empty_barrier(bio))) { 1045494b3ee7SMikulas Patocka bio->bi_bdev = s->store->cow->bdev; 1046494b3ee7SMikulas Patocka return DM_MAPIO_REMAPPED; 1047494b3ee7SMikulas Patocka } 1048494b3ee7SMikulas Patocka 104971fab00aSJonathan Brassow chunk = sector_to_chunk(s->store, bio->bi_sector); 10501da177e4SLinus Torvalds 10511da177e4SLinus Torvalds /* Full snapshots are not usable */ 105276df1c65SAlasdair G Kergon /* To get here the table must be live so s->active is always set. */ 10531da177e4SLinus Torvalds if (!s->valid) 1054f6a80ea8SAlasdair G Kergon return -EIO; 10551da177e4SLinus Torvalds 10561da177e4SLinus Torvalds /* FIXME: should only take write lock if we need 10571da177e4SLinus Torvalds * to copy an exception */ 10581da177e4SLinus Torvalds down_write(&s->lock); 10591da177e4SLinus Torvalds 106076df1c65SAlasdair G Kergon if (!s->valid) { 106176df1c65SAlasdair G Kergon r = -EIO; 106276df1c65SAlasdair G Kergon goto out_unlock; 106376df1c65SAlasdair G Kergon } 106476df1c65SAlasdair G Kergon 10651da177e4SLinus Torvalds /* If the block is already remapped - use that, else remap it */ 10661da177e4SLinus Torvalds e = lookup_exception(&s->complete, chunk); 10671da177e4SLinus Torvalds if (e) { 1068d74f81f8SMilan Broz remap_exception(s, e, bio, chunk); 106976df1c65SAlasdair G Kergon goto out_unlock; 107076df1c65SAlasdair G Kergon } 10711da177e4SLinus Torvalds 1072ba40a2aaSAlasdair G Kergon /* 1073ba40a2aaSAlasdair G Kergon * Write to snapshot - higher level takes care of RW/RO 1074ba40a2aaSAlasdair G Kergon * flags so we should only get this if we are 1075ba40a2aaSAlasdair G Kergon * writeable. 1076ba40a2aaSAlasdair G Kergon */ 1077ba40a2aaSAlasdair G Kergon if (bio_rw(bio) == WRITE) { 10782913808eSMikulas Patocka pe = __lookup_pending_exception(s, chunk); 10792913808eSMikulas Patocka if (!pe) { 1080c6621392SMikulas Patocka up_write(&s->lock); 1081c6621392SMikulas Patocka pe = alloc_pending_exception(s); 1082c6621392SMikulas Patocka down_write(&s->lock); 1083c6621392SMikulas Patocka 1084c6621392SMikulas Patocka if (!s->valid) { 1085c6621392SMikulas Patocka free_pending_exception(pe); 1086c6621392SMikulas Patocka r = -EIO; 1087c6621392SMikulas Patocka goto out_unlock; 1088c6621392SMikulas Patocka } 1089c6621392SMikulas Patocka 109035bf659bSMikulas Patocka e = lookup_exception(&s->complete, chunk); 109135bf659bSMikulas Patocka if (e) { 109235bf659bSMikulas Patocka free_pending_exception(pe); 109335bf659bSMikulas Patocka remap_exception(s, e, bio, chunk); 109435bf659bSMikulas Patocka goto out_unlock; 109535bf659bSMikulas Patocka } 109635bf659bSMikulas Patocka 1097c6621392SMikulas Patocka pe = __find_pending_exception(s, pe, chunk); 10981da177e4SLinus Torvalds if (!pe) { 1099695368acSAlasdair G Kergon __invalidate_snapshot(s, -ENOMEM); 11001da177e4SLinus Torvalds r = -EIO; 110176df1c65SAlasdair G Kergon goto out_unlock; 110276df1c65SAlasdair G Kergon } 11032913808eSMikulas Patocka } 110476df1c65SAlasdair G Kergon 1105d74f81f8SMilan Broz remap_exception(s, &pe->e, bio, chunk); 11061da177e4SLinus Torvalds bio_list_add(&pe->snapshot_bios, bio); 11071da177e4SLinus Torvalds 1108d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 1109ba40a2aaSAlasdair G Kergon 11101da177e4SLinus Torvalds if (!pe->started) { 11111da177e4SLinus Torvalds /* this is protected by snap->lock */ 11121da177e4SLinus Torvalds pe->started = 1; 111376df1c65SAlasdair G Kergon up_write(&s->lock); 111476df1c65SAlasdair G Kergon start_copy(pe); 1115ba40a2aaSAlasdair G Kergon goto out; 1116ba40a2aaSAlasdair G Kergon } 1117cd45daffSMikulas Patocka } else { 11181da177e4SLinus Torvalds bio->bi_bdev = s->origin->bdev; 1119cd45daffSMikulas Patocka map_context->ptr = track_chunk(s, chunk); 1120cd45daffSMikulas Patocka } 11211da177e4SLinus Torvalds 1122ba40a2aaSAlasdair G Kergon out_unlock: 1123ba40a2aaSAlasdair G Kergon up_write(&s->lock); 1124ba40a2aaSAlasdair G Kergon out: 11251da177e4SLinus Torvalds return r; 11261da177e4SLinus Torvalds } 11271da177e4SLinus Torvalds 1128cd45daffSMikulas Patocka static int snapshot_end_io(struct dm_target *ti, struct bio *bio, 1129cd45daffSMikulas Patocka int error, union map_info *map_context) 1130cd45daffSMikulas Patocka { 1131cd45daffSMikulas Patocka struct dm_snapshot *s = ti->private; 1132cd45daffSMikulas Patocka struct dm_snap_tracked_chunk *c = map_context->ptr; 1133cd45daffSMikulas Patocka 1134cd45daffSMikulas Patocka if (c) 1135cd45daffSMikulas Patocka stop_tracking_chunk(s, c); 1136cd45daffSMikulas Patocka 1137cd45daffSMikulas Patocka return 0; 1138cd45daffSMikulas Patocka } 1139cd45daffSMikulas Patocka 11401da177e4SLinus Torvalds static void snapshot_resume(struct dm_target *ti) 11411da177e4SLinus Torvalds { 1142028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 11431da177e4SLinus Torvalds 1144aa14edebSAlasdair G Kergon down_write(&s->lock); 1145aa14edebSAlasdair G Kergon s->active = 1; 1146aa14edebSAlasdair G Kergon up_write(&s->lock); 11471da177e4SLinus Torvalds } 11481da177e4SLinus Torvalds 11491da177e4SLinus Torvalds static int snapshot_status(struct dm_target *ti, status_type_t type, 11501da177e4SLinus Torvalds char *result, unsigned int maxlen) 11511da177e4SLinus Torvalds { 11522e4a31dfSJonathan Brassow unsigned sz = 0; 1153028867acSAlasdair G Kergon struct dm_snapshot *snap = ti->private; 11541da177e4SLinus Torvalds 11551da177e4SLinus Torvalds switch (type) { 11561da177e4SLinus Torvalds case STATUSTYPE_INFO: 115794e76572SMikulas Patocka 115894e76572SMikulas Patocka down_write(&snap->lock); 115994e76572SMikulas Patocka 11601da177e4SLinus Torvalds if (!snap->valid) 11612e4a31dfSJonathan Brassow DMEMIT("Invalid"); 11621da177e4SLinus Torvalds else { 1163493df71cSJonathan Brassow if (snap->store->type->fraction_full) { 11641da177e4SLinus Torvalds sector_t numerator, denominator; 1165493df71cSJonathan Brassow snap->store->type->fraction_full(snap->store, 11661da177e4SLinus Torvalds &numerator, 11671da177e4SLinus Torvalds &denominator); 11682e4a31dfSJonathan Brassow DMEMIT("%llu/%llu", 11694ee218cdSAndrew Morton (unsigned long long)numerator, 11704ee218cdSAndrew Morton (unsigned long long)denominator); 11711da177e4SLinus Torvalds } 11721da177e4SLinus Torvalds else 11732e4a31dfSJonathan Brassow DMEMIT("Unknown"); 11741da177e4SLinus Torvalds } 117594e76572SMikulas Patocka 117694e76572SMikulas Patocka up_write(&snap->lock); 117794e76572SMikulas Patocka 11781da177e4SLinus Torvalds break; 11791da177e4SLinus Torvalds 11801da177e4SLinus Torvalds case STATUSTYPE_TABLE: 11811da177e4SLinus Torvalds /* 11821da177e4SLinus Torvalds * kdevname returns a static pointer so we need 11831da177e4SLinus Torvalds * to make private copies if the output is to 11841da177e4SLinus Torvalds * make sense. 11851da177e4SLinus Torvalds */ 11862e4a31dfSJonathan Brassow DMEMIT("%s", snap->origin->name); 11871e302a92SJonathan Brassow snap->store->type->status(snap->store, type, result + sz, 11881e302a92SJonathan Brassow maxlen - sz); 11891da177e4SLinus Torvalds break; 11901da177e4SLinus Torvalds } 11911da177e4SLinus Torvalds 11921da177e4SLinus Torvalds return 0; 11931da177e4SLinus Torvalds } 11941da177e4SLinus Torvalds 11958811f46cSMike Snitzer static int snapshot_iterate_devices(struct dm_target *ti, 11968811f46cSMike Snitzer iterate_devices_callout_fn fn, void *data) 11978811f46cSMike Snitzer { 11988811f46cSMike Snitzer struct dm_snapshot *snap = ti->private; 11998811f46cSMike Snitzer 12008811f46cSMike Snitzer return fn(ti, snap->origin, 0, ti->len, data); 12018811f46cSMike Snitzer } 12028811f46cSMike Snitzer 12038811f46cSMike Snitzer 12041da177e4SLinus Torvalds /*----------------------------------------------------------------- 12051da177e4SLinus Torvalds * Origin methods 12061da177e4SLinus Torvalds *---------------------------------------------------------------*/ 12071da177e4SLinus Torvalds static int __origin_write(struct list_head *snapshots, struct bio *bio) 12081da177e4SLinus Torvalds { 1209d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED, first = 0; 12101da177e4SLinus Torvalds struct dm_snapshot *snap; 1211028867acSAlasdair G Kergon struct dm_snap_exception *e; 1212028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe, *next_pe, *primary_pe = NULL; 12131da177e4SLinus Torvalds chunk_t chunk; 1214eccf0817SAlasdair G Kergon LIST_HEAD(pe_queue); 12151da177e4SLinus Torvalds 12161da177e4SLinus Torvalds /* Do all the snapshots on this origin */ 12171da177e4SLinus Torvalds list_for_each_entry (snap, snapshots, list) { 12181da177e4SLinus Torvalds 121976df1c65SAlasdair G Kergon down_write(&snap->lock); 122076df1c65SAlasdair G Kergon 1221aa14edebSAlasdair G Kergon /* Only deal with valid and active snapshots */ 1222aa14edebSAlasdair G Kergon if (!snap->valid || !snap->active) 122376df1c65SAlasdair G Kergon goto next_snapshot; 12241da177e4SLinus Torvalds 1225d5e404c1SAlasdair G Kergon /* Nothing to do if writing beyond end of snapshot */ 12260cea9c78SJonathan Brassow if (bio->bi_sector >= dm_table_get_size(snap->store->ti->table)) 122776df1c65SAlasdair G Kergon goto next_snapshot; 12281da177e4SLinus Torvalds 12291da177e4SLinus Torvalds /* 12301da177e4SLinus Torvalds * Remember, different snapshots can have 12311da177e4SLinus Torvalds * different chunk sizes. 12321da177e4SLinus Torvalds */ 123371fab00aSJonathan Brassow chunk = sector_to_chunk(snap->store, bio->bi_sector); 12341da177e4SLinus Torvalds 12351da177e4SLinus Torvalds /* 12361da177e4SLinus Torvalds * Check exception table to see if block 12371da177e4SLinus Torvalds * is already remapped in this snapshot 12381da177e4SLinus Torvalds * and trigger an exception if not. 1239b4b610f6SAlasdair G Kergon * 12404b832e8dSAlasdair G Kergon * ref_count is initialised to 1 so pending_complete() 1241b4b610f6SAlasdair G Kergon * won't destroy the primary_pe while we're inside this loop. 12421da177e4SLinus Torvalds */ 12431da177e4SLinus Torvalds e = lookup_exception(&snap->complete, chunk); 124476df1c65SAlasdair G Kergon if (e) 124576df1c65SAlasdair G Kergon goto next_snapshot; 124676df1c65SAlasdair G Kergon 12472913808eSMikulas Patocka pe = __lookup_pending_exception(snap, chunk); 12482913808eSMikulas Patocka if (!pe) { 1249c6621392SMikulas Patocka up_write(&snap->lock); 1250c6621392SMikulas Patocka pe = alloc_pending_exception(snap); 1251c6621392SMikulas Patocka down_write(&snap->lock); 1252c6621392SMikulas Patocka 1253c6621392SMikulas Patocka if (!snap->valid) { 1254c6621392SMikulas Patocka free_pending_exception(pe); 1255c6621392SMikulas Patocka goto next_snapshot; 1256c6621392SMikulas Patocka } 1257c6621392SMikulas Patocka 125835bf659bSMikulas Patocka e = lookup_exception(&snap->complete, chunk); 125935bf659bSMikulas Patocka if (e) { 126035bf659bSMikulas Patocka free_pending_exception(pe); 126135bf659bSMikulas Patocka goto next_snapshot; 126235bf659bSMikulas Patocka } 126335bf659bSMikulas Patocka 1264c6621392SMikulas Patocka pe = __find_pending_exception(snap, pe, chunk); 12651da177e4SLinus Torvalds if (!pe) { 1266695368acSAlasdair G Kergon __invalidate_snapshot(snap, -ENOMEM); 126776df1c65SAlasdair G Kergon goto next_snapshot; 126876df1c65SAlasdair G Kergon } 12692913808eSMikulas Patocka } 12701da177e4SLinus Torvalds 1271b4b610f6SAlasdair G Kergon if (!primary_pe) { 1272b4b610f6SAlasdair G Kergon /* 1273b4b610f6SAlasdair G Kergon * Either every pe here has same 1274b4b610f6SAlasdair G Kergon * primary_pe or none has one yet. 1275b4b610f6SAlasdair G Kergon */ 1276b4b610f6SAlasdair G Kergon if (pe->primary_pe) 1277b4b610f6SAlasdair G Kergon primary_pe = pe->primary_pe; 1278b4b610f6SAlasdair G Kergon else { 1279b4b610f6SAlasdair G Kergon primary_pe = pe; 1280b4b610f6SAlasdair G Kergon first = 1; 1281eccf0817SAlasdair G Kergon } 1282b4b610f6SAlasdair G Kergon 128376df1c65SAlasdair G Kergon bio_list_add(&primary_pe->origin_bios, bio); 128476df1c65SAlasdair G Kergon 1285d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 1286b4b610f6SAlasdair G Kergon } 128776df1c65SAlasdair G Kergon 1288b4b610f6SAlasdair G Kergon if (!pe->primary_pe) { 1289b4b610f6SAlasdair G Kergon pe->primary_pe = primary_pe; 12904b832e8dSAlasdair G Kergon get_pending_exception(primary_pe); 1291b4b610f6SAlasdair G Kergon } 129276df1c65SAlasdair G Kergon 1293eccf0817SAlasdair G Kergon if (!pe->started) { 1294eccf0817SAlasdair G Kergon pe->started = 1; 1295eccf0817SAlasdair G Kergon list_add_tail(&pe->list, &pe_queue); 1296eccf0817SAlasdair G Kergon } 12971da177e4SLinus Torvalds 129876df1c65SAlasdair G Kergon next_snapshot: 12991da177e4SLinus Torvalds up_write(&snap->lock); 13001da177e4SLinus Torvalds } 13011da177e4SLinus Torvalds 1302b4b610f6SAlasdair G Kergon if (!primary_pe) 13034b832e8dSAlasdair G Kergon return r; 1304b4b610f6SAlasdair G Kergon 1305b4b610f6SAlasdair G Kergon /* 1306b4b610f6SAlasdair G Kergon * If this is the first time we're processing this chunk and 13074b832e8dSAlasdair G Kergon * ref_count is now 1 it means all the pending exceptions 1308b4b610f6SAlasdair G Kergon * got completed while we were in the loop above, so it falls to 1309b4b610f6SAlasdair G Kergon * us here to remove the primary_pe and submit any origin_bios. 1310b4b610f6SAlasdair G Kergon */ 1311b4b610f6SAlasdair G Kergon 13124b832e8dSAlasdair G Kergon if (first && atomic_dec_and_test(&primary_pe->ref_count)) { 1313b4b610f6SAlasdair G Kergon flush_bios(bio_list_get(&primary_pe->origin_bios)); 1314b4b610f6SAlasdair G Kergon free_pending_exception(primary_pe); 1315b4b610f6SAlasdair G Kergon /* If we got here, pe_queue is necessarily empty. */ 13164b832e8dSAlasdair G Kergon return r; 1317b4b610f6SAlasdair G Kergon } 1318b4b610f6SAlasdair G Kergon 13191da177e4SLinus Torvalds /* 13201da177e4SLinus Torvalds * Now that we have a complete pe list we can start the copying. 13211da177e4SLinus Torvalds */ 1322eccf0817SAlasdair G Kergon list_for_each_entry_safe(pe, next_pe, &pe_queue, list) 13231da177e4SLinus Torvalds start_copy(pe); 13241da177e4SLinus Torvalds 13251da177e4SLinus Torvalds return r; 13261da177e4SLinus Torvalds } 13271da177e4SLinus Torvalds 13281da177e4SLinus Torvalds /* 13291da177e4SLinus Torvalds * Called on a write from the origin driver. 13301da177e4SLinus Torvalds */ 13311da177e4SLinus Torvalds static int do_origin(struct dm_dev *origin, struct bio *bio) 13321da177e4SLinus Torvalds { 13331da177e4SLinus Torvalds struct origin *o; 1334d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED; 13351da177e4SLinus Torvalds 13361da177e4SLinus Torvalds down_read(&_origins_lock); 13371da177e4SLinus Torvalds o = __lookup_origin(origin->bdev); 13381da177e4SLinus Torvalds if (o) 13391da177e4SLinus Torvalds r = __origin_write(&o->snapshots, bio); 13401da177e4SLinus Torvalds up_read(&_origins_lock); 13411da177e4SLinus Torvalds 13421da177e4SLinus Torvalds return r; 13431da177e4SLinus Torvalds } 13441da177e4SLinus Torvalds 13451da177e4SLinus Torvalds /* 13461da177e4SLinus Torvalds * Origin: maps a linear range of a device, with hooks for snapshotting. 13471da177e4SLinus Torvalds */ 13481da177e4SLinus Torvalds 13491da177e4SLinus Torvalds /* 13501da177e4SLinus Torvalds * Construct an origin mapping: <dev_path> 13511da177e4SLinus Torvalds * The context for an origin is merely a 'struct dm_dev *' 13521da177e4SLinus Torvalds * pointing to the real device. 13531da177e4SLinus Torvalds */ 13541da177e4SLinus Torvalds static int origin_ctr(struct dm_target *ti, unsigned int argc, char **argv) 13551da177e4SLinus Torvalds { 13561da177e4SLinus Torvalds int r; 13571da177e4SLinus Torvalds struct dm_dev *dev; 13581da177e4SLinus Torvalds 13591da177e4SLinus Torvalds if (argc != 1) { 136072d94861SAlasdair G Kergon ti->error = "origin: incorrect number of arguments"; 13611da177e4SLinus Torvalds return -EINVAL; 13621da177e4SLinus Torvalds } 13631da177e4SLinus Torvalds 13641da177e4SLinus Torvalds r = dm_get_device(ti, argv[0], 0, ti->len, 13651da177e4SLinus Torvalds dm_table_get_mode(ti->table), &dev); 13661da177e4SLinus Torvalds if (r) { 13671da177e4SLinus Torvalds ti->error = "Cannot get target device"; 13681da177e4SLinus Torvalds return r; 13691da177e4SLinus Torvalds } 13701da177e4SLinus Torvalds 13711da177e4SLinus Torvalds ti->private = dev; 1372494b3ee7SMikulas Patocka ti->num_flush_requests = 1; 1373494b3ee7SMikulas Patocka 13741da177e4SLinus Torvalds return 0; 13751da177e4SLinus Torvalds } 13761da177e4SLinus Torvalds 13771da177e4SLinus Torvalds static void origin_dtr(struct dm_target *ti) 13781da177e4SLinus Torvalds { 1379028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 13801da177e4SLinus Torvalds dm_put_device(ti, dev); 13811da177e4SLinus Torvalds } 13821da177e4SLinus Torvalds 13831da177e4SLinus Torvalds static int origin_map(struct dm_target *ti, struct bio *bio, 13841da177e4SLinus Torvalds union map_info *map_context) 13851da177e4SLinus Torvalds { 1386028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 13871da177e4SLinus Torvalds bio->bi_bdev = dev->bdev; 13881da177e4SLinus Torvalds 1389494b3ee7SMikulas Patocka if (unlikely(bio_empty_barrier(bio))) 1390494b3ee7SMikulas Patocka return DM_MAPIO_REMAPPED; 1391494b3ee7SMikulas Patocka 13921da177e4SLinus Torvalds /* Only tell snapshots if this is a write */ 1393d2a7ad29SKiyoshi Ueda return (bio_rw(bio) == WRITE) ? do_origin(dev, bio) : DM_MAPIO_REMAPPED; 13941da177e4SLinus Torvalds } 13951da177e4SLinus Torvalds 13961da177e4SLinus Torvalds #define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r)) 13971da177e4SLinus Torvalds 13981da177e4SLinus Torvalds /* 13991da177e4SLinus Torvalds * Set the target "split_io" field to the minimum of all the snapshots' 14001da177e4SLinus Torvalds * chunk sizes. 14011da177e4SLinus Torvalds */ 14021da177e4SLinus Torvalds static void origin_resume(struct dm_target *ti) 14031da177e4SLinus Torvalds { 1404028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 14051da177e4SLinus Torvalds struct dm_snapshot *snap; 14061da177e4SLinus Torvalds struct origin *o; 1407df96eee6SMikulas Patocka unsigned chunk_size = 0; 14081da177e4SLinus Torvalds 14091da177e4SLinus Torvalds down_read(&_origins_lock); 14101da177e4SLinus Torvalds o = __lookup_origin(dev->bdev); 14111da177e4SLinus Torvalds if (o) 14121da177e4SLinus Torvalds list_for_each_entry (snap, &o->snapshots, list) 1413d0216849SJonathan Brassow chunk_size = min_not_zero(chunk_size, 1414d0216849SJonathan Brassow snap->store->chunk_size); 14151da177e4SLinus Torvalds up_read(&_origins_lock); 14161da177e4SLinus Torvalds 14171da177e4SLinus Torvalds ti->split_io = chunk_size; 14181da177e4SLinus Torvalds } 14191da177e4SLinus Torvalds 14201da177e4SLinus Torvalds static int origin_status(struct dm_target *ti, status_type_t type, char *result, 14211da177e4SLinus Torvalds unsigned int maxlen) 14221da177e4SLinus Torvalds { 1423028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 14241da177e4SLinus Torvalds 14251da177e4SLinus Torvalds switch (type) { 14261da177e4SLinus Torvalds case STATUSTYPE_INFO: 14271da177e4SLinus Torvalds result[0] = '\0'; 14281da177e4SLinus Torvalds break; 14291da177e4SLinus Torvalds 14301da177e4SLinus Torvalds case STATUSTYPE_TABLE: 14311da177e4SLinus Torvalds snprintf(result, maxlen, "%s", dev->name); 14321da177e4SLinus Torvalds break; 14331da177e4SLinus Torvalds } 14341da177e4SLinus Torvalds 14351da177e4SLinus Torvalds return 0; 14361da177e4SLinus Torvalds } 14371da177e4SLinus Torvalds 14388811f46cSMike Snitzer static int origin_iterate_devices(struct dm_target *ti, 14398811f46cSMike Snitzer iterate_devices_callout_fn fn, void *data) 14408811f46cSMike Snitzer { 14418811f46cSMike Snitzer struct dm_dev *dev = ti->private; 14428811f46cSMike Snitzer 14438811f46cSMike Snitzer return fn(ti, dev, 0, ti->len, data); 14448811f46cSMike Snitzer } 14458811f46cSMike Snitzer 14461da177e4SLinus Torvalds static struct target_type origin_target = { 14471da177e4SLinus Torvalds .name = "snapshot-origin", 14488811f46cSMike Snitzer .version = {1, 7, 0}, 14491da177e4SLinus Torvalds .module = THIS_MODULE, 14501da177e4SLinus Torvalds .ctr = origin_ctr, 14511da177e4SLinus Torvalds .dtr = origin_dtr, 14521da177e4SLinus Torvalds .map = origin_map, 14531da177e4SLinus Torvalds .resume = origin_resume, 14541da177e4SLinus Torvalds .status = origin_status, 14558811f46cSMike Snitzer .iterate_devices = origin_iterate_devices, 14561da177e4SLinus Torvalds }; 14571da177e4SLinus Torvalds 14581da177e4SLinus Torvalds static struct target_type snapshot_target = { 14591da177e4SLinus Torvalds .name = "snapshot", 14608811f46cSMike Snitzer .version = {1, 7, 0}, 14611da177e4SLinus Torvalds .module = THIS_MODULE, 14621da177e4SLinus Torvalds .ctr = snapshot_ctr, 14631da177e4SLinus Torvalds .dtr = snapshot_dtr, 14641da177e4SLinus Torvalds .map = snapshot_map, 1465cd45daffSMikulas Patocka .end_io = snapshot_end_io, 14661da177e4SLinus Torvalds .resume = snapshot_resume, 14671da177e4SLinus Torvalds .status = snapshot_status, 14688811f46cSMike Snitzer .iterate_devices = snapshot_iterate_devices, 14691da177e4SLinus Torvalds }; 14701da177e4SLinus Torvalds 14711da177e4SLinus Torvalds static int __init dm_snapshot_init(void) 14721da177e4SLinus Torvalds { 14731da177e4SLinus Torvalds int r; 14741da177e4SLinus Torvalds 14754db6bfe0SAlasdair G Kergon r = dm_exception_store_init(); 14764db6bfe0SAlasdair G Kergon if (r) { 14774db6bfe0SAlasdair G Kergon DMERR("Failed to initialize exception stores"); 14784db6bfe0SAlasdair G Kergon return r; 14794db6bfe0SAlasdair G Kergon } 14804db6bfe0SAlasdair G Kergon 14811da177e4SLinus Torvalds r = dm_register_target(&snapshot_target); 14821da177e4SLinus Torvalds if (r) { 14831da177e4SLinus Torvalds DMERR("snapshot target register failed %d", r); 1484034a186dSJonathan Brassow goto bad_register_snapshot_target; 14851da177e4SLinus Torvalds } 14861da177e4SLinus Torvalds 14871da177e4SLinus Torvalds r = dm_register_target(&origin_target); 14881da177e4SLinus Torvalds if (r < 0) { 148972d94861SAlasdair G Kergon DMERR("Origin target register failed %d", r); 14901da177e4SLinus Torvalds goto bad1; 14911da177e4SLinus Torvalds } 14921da177e4SLinus Torvalds 14931da177e4SLinus Torvalds r = init_origin_hash(); 14941da177e4SLinus Torvalds if (r) { 14951da177e4SLinus Torvalds DMERR("init_origin_hash failed."); 14961da177e4SLinus Torvalds goto bad2; 14971da177e4SLinus Torvalds } 14981da177e4SLinus Torvalds 1499028867acSAlasdair G Kergon exception_cache = KMEM_CACHE(dm_snap_exception, 0); 15001da177e4SLinus Torvalds if (!exception_cache) { 15011da177e4SLinus Torvalds DMERR("Couldn't create exception cache."); 15021da177e4SLinus Torvalds r = -ENOMEM; 15031da177e4SLinus Torvalds goto bad3; 15041da177e4SLinus Torvalds } 15051da177e4SLinus Torvalds 1506028867acSAlasdair G Kergon pending_cache = KMEM_CACHE(dm_snap_pending_exception, 0); 15071da177e4SLinus Torvalds if (!pending_cache) { 15081da177e4SLinus Torvalds DMERR("Couldn't create pending cache."); 15091da177e4SLinus Torvalds r = -ENOMEM; 15101da177e4SLinus Torvalds goto bad4; 15111da177e4SLinus Torvalds } 15121da177e4SLinus Torvalds 1513cd45daffSMikulas Patocka tracked_chunk_cache = KMEM_CACHE(dm_snap_tracked_chunk, 0); 1514cd45daffSMikulas Patocka if (!tracked_chunk_cache) { 1515cd45daffSMikulas Patocka DMERR("Couldn't create cache to track chunks in use."); 1516cd45daffSMikulas Patocka r = -ENOMEM; 1517cd45daffSMikulas Patocka goto bad5; 1518cd45daffSMikulas Patocka } 1519cd45daffSMikulas Patocka 1520ca3a931fSAlasdair G Kergon ksnapd = create_singlethread_workqueue("ksnapd"); 1521ca3a931fSAlasdair G Kergon if (!ksnapd) { 1522ca3a931fSAlasdair G Kergon DMERR("Failed to create ksnapd workqueue."); 1523ca3a931fSAlasdair G Kergon r = -ENOMEM; 152492e86812SMikulas Patocka goto bad_pending_pool; 1525ca3a931fSAlasdair G Kergon } 1526ca3a931fSAlasdair G Kergon 15271da177e4SLinus Torvalds return 0; 15281da177e4SLinus Torvalds 1529cd45daffSMikulas Patocka bad_pending_pool: 1530cd45daffSMikulas Patocka kmem_cache_destroy(tracked_chunk_cache); 15311da177e4SLinus Torvalds bad5: 15321da177e4SLinus Torvalds kmem_cache_destroy(pending_cache); 15331da177e4SLinus Torvalds bad4: 15341da177e4SLinus Torvalds kmem_cache_destroy(exception_cache); 15351da177e4SLinus Torvalds bad3: 15361da177e4SLinus Torvalds exit_origin_hash(); 15371da177e4SLinus Torvalds bad2: 15381da177e4SLinus Torvalds dm_unregister_target(&origin_target); 15391da177e4SLinus Torvalds bad1: 15401da177e4SLinus Torvalds dm_unregister_target(&snapshot_target); 1541034a186dSJonathan Brassow 1542034a186dSJonathan Brassow bad_register_snapshot_target: 1543034a186dSJonathan Brassow dm_exception_store_exit(); 15441da177e4SLinus Torvalds return r; 15451da177e4SLinus Torvalds } 15461da177e4SLinus Torvalds 15471da177e4SLinus Torvalds static void __exit dm_snapshot_exit(void) 15481da177e4SLinus Torvalds { 1549ca3a931fSAlasdair G Kergon destroy_workqueue(ksnapd); 1550ca3a931fSAlasdair G Kergon 155110d3bd09SMikulas Patocka dm_unregister_target(&snapshot_target); 155210d3bd09SMikulas Patocka dm_unregister_target(&origin_target); 15531da177e4SLinus Torvalds 15541da177e4SLinus Torvalds exit_origin_hash(); 15551da177e4SLinus Torvalds kmem_cache_destroy(pending_cache); 15561da177e4SLinus Torvalds kmem_cache_destroy(exception_cache); 1557cd45daffSMikulas Patocka kmem_cache_destroy(tracked_chunk_cache); 15584db6bfe0SAlasdair G Kergon 15594db6bfe0SAlasdair G Kergon dm_exception_store_exit(); 15601da177e4SLinus Torvalds } 15611da177e4SLinus Torvalds 15621da177e4SLinus Torvalds /* Module hooks */ 15631da177e4SLinus Torvalds module_init(dm_snapshot_init); 15641da177e4SLinus Torvalds module_exit(dm_snapshot_exit); 15651da177e4SLinus Torvalds 15661da177e4SLinus Torvalds MODULE_DESCRIPTION(DM_NAME " snapshot target"); 15671da177e4SLinus Torvalds MODULE_AUTHOR("Joe Thornber"); 15681da177e4SLinus Torvalds MODULE_LICENSE("GPL"); 1569