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 { 29960c856c8SMikulas Patocka struct origin *o, *new_o; 3001da177e4SLinus Torvalds struct block_device *bdev = snap->origin->bdev; 3011da177e4SLinus Torvalds 30260c856c8SMikulas Patocka new_o = kmalloc(sizeof(*new_o), GFP_KERNEL); 30360c856c8SMikulas Patocka if (!new_o) 30460c856c8SMikulas Patocka return -ENOMEM; 30560c856c8SMikulas Patocka 3061da177e4SLinus Torvalds down_write(&_origins_lock); 3071da177e4SLinus Torvalds o = __lookup_origin(bdev); 3081da177e4SLinus Torvalds 30960c856c8SMikulas Patocka if (o) 31060c856c8SMikulas Patocka kfree(new_o); 31160c856c8SMikulas Patocka else { 3121da177e4SLinus Torvalds /* New origin */ 31360c856c8SMikulas Patocka o = new_o; 3141da177e4SLinus Torvalds 3151da177e4SLinus Torvalds /* Initialise the struct */ 3161da177e4SLinus Torvalds INIT_LIST_HEAD(&o->snapshots); 3171da177e4SLinus Torvalds o->bdev = bdev; 3181da177e4SLinus Torvalds 3191da177e4SLinus Torvalds __insert_origin(o); 3201da177e4SLinus Torvalds } 3211da177e4SLinus Torvalds 3221da177e4SLinus Torvalds list_add_tail(&snap->list, &o->snapshots); 3231da177e4SLinus Torvalds 3241da177e4SLinus Torvalds up_write(&_origins_lock); 3251da177e4SLinus Torvalds return 0; 3261da177e4SLinus Torvalds } 3271da177e4SLinus Torvalds 3281da177e4SLinus Torvalds static void unregister_snapshot(struct dm_snapshot *s) 3291da177e4SLinus Torvalds { 3301da177e4SLinus Torvalds struct origin *o; 3311da177e4SLinus Torvalds 3321da177e4SLinus Torvalds down_write(&_origins_lock); 3331da177e4SLinus Torvalds o = __lookup_origin(s->origin->bdev); 3341da177e4SLinus Torvalds 3351da177e4SLinus Torvalds list_del(&s->list); 3361da177e4SLinus Torvalds if (list_empty(&o->snapshots)) { 3371da177e4SLinus Torvalds list_del(&o->hash_list); 3381da177e4SLinus Torvalds kfree(o); 3391da177e4SLinus Torvalds } 3401da177e4SLinus Torvalds 3411da177e4SLinus Torvalds up_write(&_origins_lock); 3421da177e4SLinus Torvalds } 3431da177e4SLinus Torvalds 3441da177e4SLinus Torvalds /* 3451da177e4SLinus Torvalds * Implementation of the exception hash tables. 346d74f81f8SMilan Broz * The lowest hash_shift bits of the chunk number are ignored, allowing 347d74f81f8SMilan Broz * some consecutive chunks to be grouped together. 3481da177e4SLinus Torvalds */ 349d74f81f8SMilan Broz static int init_exception_table(struct exception_table *et, uint32_t size, 350d74f81f8SMilan Broz unsigned hash_shift) 3511da177e4SLinus Torvalds { 3521da177e4SLinus Torvalds unsigned int i; 3531da177e4SLinus Torvalds 354d74f81f8SMilan Broz et->hash_shift = hash_shift; 3551da177e4SLinus Torvalds et->hash_mask = size - 1; 3561da177e4SLinus Torvalds et->table = dm_vcalloc(size, sizeof(struct list_head)); 3571da177e4SLinus Torvalds if (!et->table) 3581da177e4SLinus Torvalds return -ENOMEM; 3591da177e4SLinus Torvalds 3601da177e4SLinus Torvalds for (i = 0; i < size; i++) 3611da177e4SLinus Torvalds INIT_LIST_HEAD(et->table + i); 3621da177e4SLinus Torvalds 3631da177e4SLinus Torvalds return 0; 3641da177e4SLinus Torvalds } 3651da177e4SLinus Torvalds 366e18b890bSChristoph Lameter static void exit_exception_table(struct exception_table *et, struct kmem_cache *mem) 3671da177e4SLinus Torvalds { 3681da177e4SLinus Torvalds struct list_head *slot; 369028867acSAlasdair G Kergon struct dm_snap_exception *ex, *next; 3701da177e4SLinus Torvalds int i, size; 3711da177e4SLinus Torvalds 3721da177e4SLinus Torvalds size = et->hash_mask + 1; 3731da177e4SLinus Torvalds for (i = 0; i < size; i++) { 3741da177e4SLinus Torvalds slot = et->table + i; 3751da177e4SLinus Torvalds 3761da177e4SLinus Torvalds list_for_each_entry_safe (ex, next, slot, hash_list) 3771da177e4SLinus Torvalds kmem_cache_free(mem, ex); 3781da177e4SLinus Torvalds } 3791da177e4SLinus Torvalds 3801da177e4SLinus Torvalds vfree(et->table); 3811da177e4SLinus Torvalds } 3821da177e4SLinus Torvalds 383028867acSAlasdair G Kergon static uint32_t exception_hash(struct exception_table *et, chunk_t chunk) 3841da177e4SLinus Torvalds { 385d74f81f8SMilan Broz return (chunk >> et->hash_shift) & et->hash_mask; 3861da177e4SLinus Torvalds } 3871da177e4SLinus Torvalds 388028867acSAlasdair G Kergon static void insert_exception(struct exception_table *eh, 389028867acSAlasdair G Kergon struct dm_snap_exception *e) 3901da177e4SLinus Torvalds { 3911da177e4SLinus Torvalds struct list_head *l = &eh->table[exception_hash(eh, e->old_chunk)]; 3921da177e4SLinus Torvalds list_add(&e->hash_list, l); 3931da177e4SLinus Torvalds } 3941da177e4SLinus Torvalds 395028867acSAlasdair G Kergon static void remove_exception(struct dm_snap_exception *e) 3961da177e4SLinus Torvalds { 3971da177e4SLinus Torvalds list_del(&e->hash_list); 3981da177e4SLinus Torvalds } 3991da177e4SLinus Torvalds 4001da177e4SLinus Torvalds /* 4011da177e4SLinus Torvalds * Return the exception data for a sector, or NULL if not 4021da177e4SLinus Torvalds * remapped. 4031da177e4SLinus Torvalds */ 404028867acSAlasdair G Kergon static struct dm_snap_exception *lookup_exception(struct exception_table *et, 4051da177e4SLinus Torvalds chunk_t chunk) 4061da177e4SLinus Torvalds { 4071da177e4SLinus Torvalds struct list_head *slot; 408028867acSAlasdair G Kergon struct dm_snap_exception *e; 4091da177e4SLinus Torvalds 4101da177e4SLinus Torvalds slot = &et->table[exception_hash(et, chunk)]; 4111da177e4SLinus Torvalds list_for_each_entry (e, slot, hash_list) 412d74f81f8SMilan Broz if (chunk >= e->old_chunk && 413d74f81f8SMilan Broz chunk <= e->old_chunk + dm_consecutive_chunk_count(e)) 4141da177e4SLinus Torvalds return e; 4151da177e4SLinus Torvalds 4161da177e4SLinus Torvalds return NULL; 4171da177e4SLinus Torvalds } 4181da177e4SLinus Torvalds 419028867acSAlasdair G Kergon static struct dm_snap_exception *alloc_exception(void) 4201da177e4SLinus Torvalds { 421028867acSAlasdair G Kergon struct dm_snap_exception *e; 4221da177e4SLinus Torvalds 4231da177e4SLinus Torvalds e = kmem_cache_alloc(exception_cache, GFP_NOIO); 4241da177e4SLinus Torvalds if (!e) 4251da177e4SLinus Torvalds e = kmem_cache_alloc(exception_cache, GFP_ATOMIC); 4261da177e4SLinus Torvalds 4271da177e4SLinus Torvalds return e; 4281da177e4SLinus Torvalds } 4291da177e4SLinus Torvalds 430028867acSAlasdair G Kergon static void free_exception(struct dm_snap_exception *e) 4311da177e4SLinus Torvalds { 4321da177e4SLinus Torvalds kmem_cache_free(exception_cache, e); 4331da177e4SLinus Torvalds } 4341da177e4SLinus Torvalds 43592e86812SMikulas Patocka static struct dm_snap_pending_exception *alloc_pending_exception(struct dm_snapshot *s) 4361da177e4SLinus Torvalds { 43792e86812SMikulas Patocka struct dm_snap_pending_exception *pe = mempool_alloc(s->pending_pool, 43892e86812SMikulas Patocka GFP_NOIO); 43992e86812SMikulas Patocka 440879129d2SMikulas Patocka atomic_inc(&s->pending_exceptions_count); 44192e86812SMikulas Patocka pe->snap = s; 44292e86812SMikulas Patocka 44392e86812SMikulas Patocka return pe; 4441da177e4SLinus Torvalds } 4451da177e4SLinus Torvalds 446028867acSAlasdair G Kergon static void free_pending_exception(struct dm_snap_pending_exception *pe) 4471da177e4SLinus Torvalds { 448879129d2SMikulas Patocka struct dm_snapshot *s = pe->snap; 449879129d2SMikulas Patocka 450879129d2SMikulas Patocka mempool_free(pe, s->pending_pool); 451879129d2SMikulas Patocka smp_mb__before_atomic_dec(); 452879129d2SMikulas Patocka atomic_dec(&s->pending_exceptions_count); 4531da177e4SLinus Torvalds } 4541da177e4SLinus Torvalds 455d74f81f8SMilan Broz static void insert_completed_exception(struct dm_snapshot *s, 456d74f81f8SMilan Broz struct dm_snap_exception *new_e) 457d74f81f8SMilan Broz { 458d74f81f8SMilan Broz struct exception_table *eh = &s->complete; 459d74f81f8SMilan Broz struct list_head *l; 460d74f81f8SMilan Broz struct dm_snap_exception *e = NULL; 461d74f81f8SMilan Broz 462d74f81f8SMilan Broz l = &eh->table[exception_hash(eh, new_e->old_chunk)]; 463d74f81f8SMilan Broz 464d74f81f8SMilan Broz /* Add immediately if this table doesn't support consecutive chunks */ 465d74f81f8SMilan Broz if (!eh->hash_shift) 466d74f81f8SMilan Broz goto out; 467d74f81f8SMilan Broz 468d74f81f8SMilan Broz /* List is ordered by old_chunk */ 469d74f81f8SMilan Broz list_for_each_entry_reverse(e, l, hash_list) { 470d74f81f8SMilan Broz /* Insert after an existing chunk? */ 471d74f81f8SMilan Broz if (new_e->old_chunk == (e->old_chunk + 472d74f81f8SMilan Broz dm_consecutive_chunk_count(e) + 1) && 473d74f81f8SMilan Broz new_e->new_chunk == (dm_chunk_number(e->new_chunk) + 474d74f81f8SMilan Broz dm_consecutive_chunk_count(e) + 1)) { 475d74f81f8SMilan Broz dm_consecutive_chunk_count_inc(e); 476d74f81f8SMilan Broz free_exception(new_e); 477d74f81f8SMilan Broz return; 478d74f81f8SMilan Broz } 479d74f81f8SMilan Broz 480d74f81f8SMilan Broz /* Insert before an existing chunk? */ 481d74f81f8SMilan Broz if (new_e->old_chunk == (e->old_chunk - 1) && 482d74f81f8SMilan Broz new_e->new_chunk == (dm_chunk_number(e->new_chunk) - 1)) { 483d74f81f8SMilan Broz dm_consecutive_chunk_count_inc(e); 484d74f81f8SMilan Broz e->old_chunk--; 485d74f81f8SMilan Broz e->new_chunk--; 486d74f81f8SMilan Broz free_exception(new_e); 487d74f81f8SMilan Broz return; 488d74f81f8SMilan Broz } 489d74f81f8SMilan Broz 490d74f81f8SMilan Broz if (new_e->old_chunk > e->old_chunk) 491d74f81f8SMilan Broz break; 492d74f81f8SMilan Broz } 493d74f81f8SMilan Broz 494d74f81f8SMilan Broz out: 495d74f81f8SMilan Broz list_add(&new_e->hash_list, e ? &e->hash_list : l); 496d74f81f8SMilan Broz } 497d74f81f8SMilan Broz 498a159c1acSJonathan Brassow /* 499a159c1acSJonathan Brassow * Callback used by the exception stores to load exceptions when 500a159c1acSJonathan Brassow * initialising. 501a159c1acSJonathan Brassow */ 502a159c1acSJonathan Brassow static int dm_add_exception(void *context, chunk_t old, chunk_t new) 5031da177e4SLinus Torvalds { 504a159c1acSJonathan Brassow struct dm_snapshot *s = context; 505028867acSAlasdair G Kergon struct dm_snap_exception *e; 5061da177e4SLinus Torvalds 5071da177e4SLinus Torvalds e = alloc_exception(); 5081da177e4SLinus Torvalds if (!e) 5091da177e4SLinus Torvalds return -ENOMEM; 5101da177e4SLinus Torvalds 5111da177e4SLinus Torvalds e->old_chunk = old; 512d74f81f8SMilan Broz 513d74f81f8SMilan Broz /* Consecutive_count is implicitly initialised to zero */ 5141da177e4SLinus Torvalds e->new_chunk = new; 515d74f81f8SMilan Broz 516d74f81f8SMilan Broz insert_completed_exception(s, e); 517d74f81f8SMilan Broz 5181da177e4SLinus Torvalds return 0; 5191da177e4SLinus Torvalds } 5201da177e4SLinus Torvalds 5211da177e4SLinus Torvalds /* 5221da177e4SLinus Torvalds * Hard coded magic. 5231da177e4SLinus Torvalds */ 5241da177e4SLinus Torvalds static int calc_max_buckets(void) 5251da177e4SLinus Torvalds { 5261da177e4SLinus Torvalds /* use a fixed size of 2MB */ 5271da177e4SLinus Torvalds unsigned long mem = 2 * 1024 * 1024; 5281da177e4SLinus Torvalds mem /= sizeof(struct list_head); 5291da177e4SLinus Torvalds 5301da177e4SLinus Torvalds return mem; 5311da177e4SLinus Torvalds } 5321da177e4SLinus Torvalds 5331da177e4SLinus Torvalds /* 5341da177e4SLinus Torvalds * Allocate room for a suitable hash table. 5351da177e4SLinus Torvalds */ 536fee1998eSJonathan Brassow static int init_hash_tables(struct dm_snapshot *s) 5371da177e4SLinus Torvalds { 5381da177e4SLinus Torvalds sector_t hash_size, cow_dev_size, origin_dev_size, max_buckets; 5391da177e4SLinus Torvalds 5401da177e4SLinus Torvalds /* 5411da177e4SLinus Torvalds * Calculate based on the size of the original volume or 5421da177e4SLinus Torvalds * the COW volume... 5431da177e4SLinus Torvalds */ 544fee1998eSJonathan Brassow cow_dev_size = get_dev_size(s->store->cow->bdev); 5451da177e4SLinus Torvalds origin_dev_size = get_dev_size(s->origin->bdev); 5461da177e4SLinus Torvalds max_buckets = calc_max_buckets(); 5471da177e4SLinus Torvalds 548fee1998eSJonathan Brassow hash_size = min(origin_dev_size, cow_dev_size) >> s->store->chunk_shift; 5491da177e4SLinus Torvalds hash_size = min(hash_size, max_buckets); 5501da177e4SLinus Torvalds 5518defd830SRobert P. J. Day hash_size = rounddown_pow_of_two(hash_size); 552d74f81f8SMilan Broz if (init_exception_table(&s->complete, hash_size, 553d74f81f8SMilan Broz DM_CHUNK_CONSECUTIVE_BITS)) 5541da177e4SLinus Torvalds return -ENOMEM; 5551da177e4SLinus Torvalds 5561da177e4SLinus Torvalds /* 5571da177e4SLinus Torvalds * Allocate hash table for in-flight exceptions 5581da177e4SLinus Torvalds * Make this smaller than the real hash table 5591da177e4SLinus Torvalds */ 5601da177e4SLinus Torvalds hash_size >>= 3; 5611da177e4SLinus Torvalds if (hash_size < 64) 5621da177e4SLinus Torvalds hash_size = 64; 5631da177e4SLinus Torvalds 564d74f81f8SMilan Broz if (init_exception_table(&s->pending, hash_size, 0)) { 5651da177e4SLinus Torvalds exit_exception_table(&s->complete, exception_cache); 5661da177e4SLinus Torvalds return -ENOMEM; 5671da177e4SLinus Torvalds } 5681da177e4SLinus Torvalds 5691da177e4SLinus Torvalds return 0; 5701da177e4SLinus Torvalds } 5711da177e4SLinus Torvalds 5721da177e4SLinus Torvalds /* 5731da177e4SLinus Torvalds * Construct a snapshot mapping: <origin_dev> <COW-dev> <p/n> <chunk-size> 5741da177e4SLinus Torvalds */ 5751da177e4SLinus Torvalds static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv) 5761da177e4SLinus Torvalds { 5771da177e4SLinus Torvalds struct dm_snapshot *s; 578cd45daffSMikulas Patocka int i; 5791da177e4SLinus Torvalds int r = -EINVAL; 5801da177e4SLinus Torvalds char *origin_path; 581fee1998eSJonathan Brassow struct dm_exception_store *store; 582fee1998eSJonathan Brassow unsigned args_used; 5831da177e4SLinus Torvalds 5844c7e3bf4SMark McLoughlin if (argc != 4) { 58572d94861SAlasdair G Kergon ti->error = "requires exactly 4 arguments"; 5861da177e4SLinus Torvalds r = -EINVAL; 587fee1998eSJonathan Brassow goto bad_args; 5881da177e4SLinus Torvalds } 5891da177e4SLinus Torvalds 5901da177e4SLinus Torvalds origin_path = argv[0]; 591fee1998eSJonathan Brassow argv++; 592fee1998eSJonathan Brassow argc--; 5931da177e4SLinus Torvalds 594fee1998eSJonathan Brassow r = dm_exception_store_create(ti, argc, argv, &args_used, &store); 595fee1998eSJonathan Brassow if (r) { 596fee1998eSJonathan Brassow ti->error = "Couldn't create exception store"; 5971da177e4SLinus Torvalds r = -EINVAL; 598fee1998eSJonathan Brassow goto bad_args; 5991da177e4SLinus Torvalds } 6001da177e4SLinus Torvalds 601fee1998eSJonathan Brassow argv += args_used; 602fee1998eSJonathan Brassow argc -= args_used; 603fee1998eSJonathan Brassow 6041da177e4SLinus Torvalds s = kmalloc(sizeof(*s), GFP_KERNEL); 605fee1998eSJonathan Brassow if (!s) { 6061da177e4SLinus Torvalds ti->error = "Cannot allocate snapshot context private " 6071da177e4SLinus Torvalds "structure"; 6081da177e4SLinus Torvalds r = -ENOMEM; 609fee1998eSJonathan Brassow goto bad_snap; 6101da177e4SLinus Torvalds } 6111da177e4SLinus Torvalds 6121da177e4SLinus Torvalds r = dm_get_device(ti, origin_path, 0, ti->len, FMODE_READ, &s->origin); 6131da177e4SLinus Torvalds if (r) { 6141da177e4SLinus Torvalds ti->error = "Cannot get origin device"; 615fee1998eSJonathan Brassow goto bad_origin; 6161da177e4SLinus Torvalds } 6171da177e4SLinus Torvalds 618fee1998eSJonathan Brassow s->store = store; 6191da177e4SLinus Torvalds s->valid = 1; 620aa14edebSAlasdair G Kergon s->active = 0; 621879129d2SMikulas Patocka atomic_set(&s->pending_exceptions_count, 0); 6221da177e4SLinus Torvalds init_rwsem(&s->lock); 623ca3a931fSAlasdair G Kergon spin_lock_init(&s->pe_lock); 6241da177e4SLinus Torvalds 6251da177e4SLinus Torvalds /* Allocate hash table for COW data */ 626fee1998eSJonathan Brassow if (init_hash_tables(s)) { 6271da177e4SLinus Torvalds ti->error = "Unable to allocate hash table space"; 6281da177e4SLinus Torvalds r = -ENOMEM; 629fee1998eSJonathan Brassow goto bad_hash_tables; 6301da177e4SLinus Torvalds } 6311da177e4SLinus Torvalds 632eb69aca5SHeinz Mauelshagen r = dm_kcopyd_client_create(SNAPSHOT_PAGES, &s->kcopyd_client); 6331da177e4SLinus Torvalds if (r) { 6341da177e4SLinus Torvalds ti->error = "Could not create kcopyd client"; 635fee1998eSJonathan Brassow goto bad_kcopyd; 6361da177e4SLinus Torvalds } 6371da177e4SLinus Torvalds 63892e86812SMikulas Patocka s->pending_pool = mempool_create_slab_pool(MIN_IOS, pending_cache); 63992e86812SMikulas Patocka if (!s->pending_pool) { 64092e86812SMikulas Patocka ti->error = "Could not allocate mempool for pending exceptions"; 641fee1998eSJonathan Brassow goto bad_pending_pool; 64292e86812SMikulas Patocka } 64392e86812SMikulas Patocka 644cd45daffSMikulas Patocka s->tracked_chunk_pool = mempool_create_slab_pool(MIN_IOS, 645cd45daffSMikulas Patocka tracked_chunk_cache); 646cd45daffSMikulas Patocka if (!s->tracked_chunk_pool) { 647cd45daffSMikulas Patocka ti->error = "Could not allocate tracked_chunk mempool for " 648cd45daffSMikulas Patocka "tracking reads"; 64992e86812SMikulas Patocka goto bad_tracked_chunk_pool; 650cd45daffSMikulas Patocka } 651cd45daffSMikulas Patocka 652cd45daffSMikulas Patocka for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) 653cd45daffSMikulas Patocka INIT_HLIST_HEAD(&s->tracked_chunk_hash[i]); 654cd45daffSMikulas Patocka 655cd45daffSMikulas Patocka spin_lock_init(&s->tracked_chunk_lock); 656cd45daffSMikulas Patocka 657aa14edebSAlasdair G Kergon /* Metadata must only be loaded into one table at once */ 658493df71cSJonathan Brassow r = s->store->type->read_metadata(s->store, dm_add_exception, 659493df71cSJonathan Brassow (void *)s); 6600764147bSMilan Broz if (r < 0) { 661f9cea4f7SMark McLoughlin ti->error = "Failed to read snapshot metadata"; 662cd45daffSMikulas Patocka goto bad_load_and_register; 6630764147bSMilan Broz } else if (r > 0) { 6640764147bSMilan Broz s->valid = 0; 6650764147bSMilan Broz DMWARN("Snapshot is marked invalid."); 666f9cea4f7SMark McLoughlin } 667aa14edebSAlasdair G Kergon 668ca3a931fSAlasdair G Kergon bio_list_init(&s->queued_bios); 669c4028958SDavid Howells INIT_WORK(&s->queued_bios_work, flush_queued_bios); 670ca3a931fSAlasdair G Kergon 6711da177e4SLinus Torvalds /* Add snapshot to the list of snapshots for this origin */ 672aa14edebSAlasdair G Kergon /* Exceptions aren't triggered till snapshot_resume() is called */ 6731da177e4SLinus Torvalds if (register_snapshot(s)) { 6741da177e4SLinus Torvalds r = -EINVAL; 6751da177e4SLinus Torvalds ti->error = "Cannot register snapshot origin"; 676cd45daffSMikulas Patocka goto bad_load_and_register; 6771da177e4SLinus Torvalds } 6781da177e4SLinus Torvalds 6791da177e4SLinus Torvalds ti->private = s; 680d0216849SJonathan Brassow ti->split_io = s->store->chunk_size; 681494b3ee7SMikulas Patocka ti->num_flush_requests = 1; 6821da177e4SLinus Torvalds 6831da177e4SLinus Torvalds return 0; 6841da177e4SLinus Torvalds 685cd45daffSMikulas Patocka bad_load_and_register: 686cd45daffSMikulas Patocka mempool_destroy(s->tracked_chunk_pool); 687cd45daffSMikulas Patocka 68892e86812SMikulas Patocka bad_tracked_chunk_pool: 68992e86812SMikulas Patocka mempool_destroy(s->pending_pool); 69092e86812SMikulas Patocka 691fee1998eSJonathan Brassow bad_pending_pool: 692eb69aca5SHeinz Mauelshagen dm_kcopyd_client_destroy(s->kcopyd_client); 6931da177e4SLinus Torvalds 694fee1998eSJonathan Brassow bad_kcopyd: 6951da177e4SLinus Torvalds exit_exception_table(&s->pending, pending_cache); 6961da177e4SLinus Torvalds exit_exception_table(&s->complete, exception_cache); 6971da177e4SLinus Torvalds 698fee1998eSJonathan Brassow bad_hash_tables: 6991da177e4SLinus Torvalds dm_put_device(ti, s->origin); 7001da177e4SLinus Torvalds 701fee1998eSJonathan Brassow bad_origin: 7021da177e4SLinus Torvalds kfree(s); 7031da177e4SLinus Torvalds 704fee1998eSJonathan Brassow bad_snap: 705fee1998eSJonathan Brassow dm_exception_store_destroy(store); 706fee1998eSJonathan Brassow 707fee1998eSJonathan Brassow bad_args: 7081da177e4SLinus Torvalds return r; 7091da177e4SLinus Torvalds } 7101da177e4SLinus Torvalds 71131c93a0cSMilan Broz static void __free_exceptions(struct dm_snapshot *s) 71231c93a0cSMilan Broz { 713eb69aca5SHeinz Mauelshagen dm_kcopyd_client_destroy(s->kcopyd_client); 71431c93a0cSMilan Broz s->kcopyd_client = NULL; 71531c93a0cSMilan Broz 71631c93a0cSMilan Broz exit_exception_table(&s->pending, pending_cache); 71731c93a0cSMilan Broz exit_exception_table(&s->complete, exception_cache); 71831c93a0cSMilan Broz } 71931c93a0cSMilan Broz 7201da177e4SLinus Torvalds static void snapshot_dtr(struct dm_target *ti) 7211da177e4SLinus Torvalds { 722cd45daffSMikulas Patocka #ifdef CONFIG_DM_DEBUG 723cd45daffSMikulas Patocka int i; 724cd45daffSMikulas Patocka #endif 725028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 7261da177e4SLinus Torvalds 727ca3a931fSAlasdair G Kergon flush_workqueue(ksnapd); 728ca3a931fSAlasdair G Kergon 729138728dcSAlasdair G Kergon /* Prevent further origin writes from using this snapshot. */ 730138728dcSAlasdair G Kergon /* After this returns there can be no new kcopyd jobs. */ 7311da177e4SLinus Torvalds unregister_snapshot(s); 7321da177e4SLinus Torvalds 733879129d2SMikulas Patocka while (atomic_read(&s->pending_exceptions_count)) 73490fa1527SMikulas Patocka msleep(1); 735879129d2SMikulas Patocka /* 736879129d2SMikulas Patocka * Ensure instructions in mempool_destroy aren't reordered 737879129d2SMikulas Patocka * before atomic_read. 738879129d2SMikulas Patocka */ 739879129d2SMikulas Patocka smp_mb(); 740879129d2SMikulas Patocka 741cd45daffSMikulas Patocka #ifdef CONFIG_DM_DEBUG 742cd45daffSMikulas Patocka for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) 743cd45daffSMikulas Patocka BUG_ON(!hlist_empty(&s->tracked_chunk_hash[i])); 744cd45daffSMikulas Patocka #endif 745cd45daffSMikulas Patocka 746cd45daffSMikulas Patocka mempool_destroy(s->tracked_chunk_pool); 747cd45daffSMikulas Patocka 74831c93a0cSMilan Broz __free_exceptions(s); 7491da177e4SLinus Torvalds 75092e86812SMikulas Patocka mempool_destroy(s->pending_pool); 75192e86812SMikulas Patocka 7521da177e4SLinus Torvalds dm_put_device(ti, s->origin); 753fee1998eSJonathan Brassow 754fee1998eSJonathan Brassow dm_exception_store_destroy(s->store); 755138728dcSAlasdair G Kergon 7561da177e4SLinus Torvalds kfree(s); 7571da177e4SLinus Torvalds } 7581da177e4SLinus Torvalds 7591da177e4SLinus Torvalds /* 7601da177e4SLinus Torvalds * Flush a list of buffers. 7611da177e4SLinus Torvalds */ 7621da177e4SLinus Torvalds static void flush_bios(struct bio *bio) 7631da177e4SLinus Torvalds { 7641da177e4SLinus Torvalds struct bio *n; 7651da177e4SLinus Torvalds 7661da177e4SLinus Torvalds while (bio) { 7671da177e4SLinus Torvalds n = bio->bi_next; 7681da177e4SLinus Torvalds bio->bi_next = NULL; 7691da177e4SLinus Torvalds generic_make_request(bio); 7701da177e4SLinus Torvalds bio = n; 7711da177e4SLinus Torvalds } 7721da177e4SLinus Torvalds } 7731da177e4SLinus Torvalds 774c4028958SDavid Howells static void flush_queued_bios(struct work_struct *work) 775ca3a931fSAlasdair G Kergon { 776c4028958SDavid Howells struct dm_snapshot *s = 777c4028958SDavid Howells container_of(work, struct dm_snapshot, queued_bios_work); 778ca3a931fSAlasdair G Kergon struct bio *queued_bios; 779ca3a931fSAlasdair G Kergon unsigned long flags; 780ca3a931fSAlasdair G Kergon 781ca3a931fSAlasdair G Kergon spin_lock_irqsave(&s->pe_lock, flags); 782ca3a931fSAlasdair G Kergon queued_bios = bio_list_get(&s->queued_bios); 783ca3a931fSAlasdair G Kergon spin_unlock_irqrestore(&s->pe_lock, flags); 784ca3a931fSAlasdair G Kergon 785ca3a931fSAlasdair G Kergon flush_bios(queued_bios); 786ca3a931fSAlasdair G Kergon } 787ca3a931fSAlasdair G Kergon 7881da177e4SLinus Torvalds /* 7891da177e4SLinus Torvalds * Error a list of buffers. 7901da177e4SLinus Torvalds */ 7911da177e4SLinus Torvalds static void error_bios(struct bio *bio) 7921da177e4SLinus Torvalds { 7931da177e4SLinus Torvalds struct bio *n; 7941da177e4SLinus Torvalds 7951da177e4SLinus Torvalds while (bio) { 7961da177e4SLinus Torvalds n = bio->bi_next; 7971da177e4SLinus Torvalds bio->bi_next = NULL; 7986712ecf8SNeilBrown bio_io_error(bio); 7991da177e4SLinus Torvalds bio = n; 8001da177e4SLinus Torvalds } 8011da177e4SLinus Torvalds } 8021da177e4SLinus Torvalds 803695368acSAlasdair G Kergon static void __invalidate_snapshot(struct dm_snapshot *s, int err) 80476df1c65SAlasdair G Kergon { 80576df1c65SAlasdair G Kergon if (!s->valid) 80676df1c65SAlasdair G Kergon return; 80776df1c65SAlasdair G Kergon 80876df1c65SAlasdair G Kergon if (err == -EIO) 80976df1c65SAlasdair G Kergon DMERR("Invalidating snapshot: Error reading/writing."); 81076df1c65SAlasdair G Kergon else if (err == -ENOMEM) 81176df1c65SAlasdair G Kergon DMERR("Invalidating snapshot: Unable to allocate exception."); 81276df1c65SAlasdair G Kergon 813493df71cSJonathan Brassow if (s->store->type->drop_snapshot) 814493df71cSJonathan Brassow s->store->type->drop_snapshot(s->store); 81576df1c65SAlasdair G Kergon 81676df1c65SAlasdair G Kergon s->valid = 0; 81776df1c65SAlasdair G Kergon 8180cea9c78SJonathan Brassow dm_table_event(s->store->ti->table); 81976df1c65SAlasdair G Kergon } 82076df1c65SAlasdair G Kergon 821028867acSAlasdair G Kergon static void get_pending_exception(struct dm_snap_pending_exception *pe) 8224b832e8dSAlasdair G Kergon { 8234b832e8dSAlasdair G Kergon atomic_inc(&pe->ref_count); 8244b832e8dSAlasdair G Kergon } 8254b832e8dSAlasdair G Kergon 826028867acSAlasdair G Kergon static struct bio *put_pending_exception(struct dm_snap_pending_exception *pe) 8274b832e8dSAlasdair G Kergon { 828028867acSAlasdair G Kergon struct dm_snap_pending_exception *primary_pe; 8294b832e8dSAlasdair G Kergon struct bio *origin_bios = NULL; 8304b832e8dSAlasdair G Kergon 8314b832e8dSAlasdair G Kergon primary_pe = pe->primary_pe; 8324b832e8dSAlasdair G Kergon 8334b832e8dSAlasdair G Kergon /* 8344b832e8dSAlasdair G Kergon * If this pe is involved in a write to the origin and 8354b832e8dSAlasdair G Kergon * it is the last sibling to complete then release 8364b832e8dSAlasdair G Kergon * the bios for the original write to the origin. 8374b832e8dSAlasdair G Kergon */ 8384b832e8dSAlasdair G Kergon if (primary_pe && 8397c5f78b9SMikulas Patocka atomic_dec_and_test(&primary_pe->ref_count)) { 8404b832e8dSAlasdair G Kergon origin_bios = bio_list_get(&primary_pe->origin_bios); 8417c5f78b9SMikulas Patocka free_pending_exception(primary_pe); 8427c5f78b9SMikulas Patocka } 8434b832e8dSAlasdair G Kergon 8444b832e8dSAlasdair G Kergon /* 8454b832e8dSAlasdair G Kergon * Free the pe if it's not linked to an origin write or if 8464b832e8dSAlasdair G Kergon * it's not itself a primary pe. 8474b832e8dSAlasdair G Kergon */ 8484b832e8dSAlasdair G Kergon if (!primary_pe || primary_pe != pe) 8494b832e8dSAlasdair G Kergon free_pending_exception(pe); 8504b832e8dSAlasdair G Kergon 8514b832e8dSAlasdair G Kergon return origin_bios; 8524b832e8dSAlasdair G Kergon } 8534b832e8dSAlasdair G Kergon 854028867acSAlasdair G Kergon static void pending_complete(struct dm_snap_pending_exception *pe, int success) 8551da177e4SLinus Torvalds { 856028867acSAlasdair G Kergon struct dm_snap_exception *e; 8571da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 8589d493fa8SAlasdair G Kergon struct bio *origin_bios = NULL; 8599d493fa8SAlasdair G Kergon struct bio *snapshot_bios = NULL; 8609d493fa8SAlasdair G Kergon int error = 0; 8611da177e4SLinus Torvalds 86276df1c65SAlasdair G Kergon if (!success) { 86376df1c65SAlasdair G Kergon /* Read/write error - snapshot is unusable */ 8641da177e4SLinus Torvalds down_write(&s->lock); 865695368acSAlasdair G Kergon __invalidate_snapshot(s, -EIO); 8669d493fa8SAlasdair G Kergon error = 1; 86776df1c65SAlasdair G Kergon goto out; 86876df1c65SAlasdair G Kergon } 86976df1c65SAlasdair G Kergon 87076df1c65SAlasdair G Kergon e = alloc_exception(); 87176df1c65SAlasdair G Kergon if (!e) { 87276df1c65SAlasdair G Kergon down_write(&s->lock); 873695368acSAlasdair G Kergon __invalidate_snapshot(s, -ENOMEM); 8749d493fa8SAlasdair G Kergon error = 1; 8751da177e4SLinus Torvalds goto out; 8761da177e4SLinus Torvalds } 8771da177e4SLinus Torvalds *e = pe->e; 8781da177e4SLinus Torvalds 8799d493fa8SAlasdair G Kergon down_write(&s->lock); 8809d493fa8SAlasdair G Kergon if (!s->valid) { 8819d493fa8SAlasdair G Kergon free_exception(e); 8829d493fa8SAlasdair G Kergon error = 1; 8839d493fa8SAlasdair G Kergon goto out; 8849d493fa8SAlasdair G Kergon } 8859d493fa8SAlasdair G Kergon 8861da177e4SLinus Torvalds /* 887a8d41b59SMikulas Patocka * Check for conflicting reads. This is extremely improbable, 88890fa1527SMikulas Patocka * so msleep(1) is sufficient and there is no need for a wait queue. 889a8d41b59SMikulas Patocka */ 890a8d41b59SMikulas Patocka while (__chunk_is_tracked(s, pe->e.old_chunk)) 89190fa1527SMikulas Patocka msleep(1); 892a8d41b59SMikulas Patocka 893a8d41b59SMikulas Patocka /* 8941da177e4SLinus Torvalds * Add a proper exception, and remove the 8951da177e4SLinus Torvalds * in-flight exception from the list. 8961da177e4SLinus Torvalds */ 897d74f81f8SMilan Broz insert_completed_exception(s, e); 8981da177e4SLinus Torvalds 8991da177e4SLinus Torvalds out: 900695368acSAlasdair G Kergon remove_exception(&pe->e); 9019d493fa8SAlasdair G Kergon snapshot_bios = bio_list_get(&pe->snapshot_bios); 9024b832e8dSAlasdair G Kergon origin_bios = put_pending_exception(pe); 903b4b610f6SAlasdair G Kergon 9049d493fa8SAlasdair G Kergon up_write(&s->lock); 9059d493fa8SAlasdair G Kergon 9069d493fa8SAlasdair G Kergon /* Submit any pending write bios */ 9079d493fa8SAlasdair G Kergon if (error) 9089d493fa8SAlasdair G Kergon error_bios(snapshot_bios); 9099d493fa8SAlasdair G Kergon else 9109d493fa8SAlasdair G Kergon flush_bios(snapshot_bios); 9119d493fa8SAlasdair G Kergon 9129d493fa8SAlasdair G Kergon flush_bios(origin_bios); 9131da177e4SLinus Torvalds } 9141da177e4SLinus Torvalds 9151da177e4SLinus Torvalds static void commit_callback(void *context, int success) 9161da177e4SLinus Torvalds { 917028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = context; 918028867acSAlasdair G Kergon 9191da177e4SLinus Torvalds pending_complete(pe, success); 9201da177e4SLinus Torvalds } 9211da177e4SLinus Torvalds 9221da177e4SLinus Torvalds /* 9231da177e4SLinus Torvalds * Called when the copy I/O has finished. kcopyd actually runs 9241da177e4SLinus Torvalds * this code so don't block. 9251da177e4SLinus Torvalds */ 9264cdc1d1fSAlasdair G Kergon static void copy_callback(int read_err, unsigned long write_err, void *context) 9271da177e4SLinus Torvalds { 928028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = context; 9291da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 9301da177e4SLinus Torvalds 9311da177e4SLinus Torvalds if (read_err || write_err) 9321da177e4SLinus Torvalds pending_complete(pe, 0); 9331da177e4SLinus Torvalds 9341da177e4SLinus Torvalds else 9351da177e4SLinus Torvalds /* Update the metadata if we are persistent */ 936493df71cSJonathan Brassow s->store->type->commit_exception(s->store, &pe->e, 937b2a11465SJonathan Brassow commit_callback, pe); 9381da177e4SLinus Torvalds } 9391da177e4SLinus Torvalds 9401da177e4SLinus Torvalds /* 9411da177e4SLinus Torvalds * Dispatches the copy operation to kcopyd. 9421da177e4SLinus Torvalds */ 943028867acSAlasdair G Kergon static void start_copy(struct dm_snap_pending_exception *pe) 9441da177e4SLinus Torvalds { 9451da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 94622a1ceb1SHeinz Mauelshagen struct dm_io_region src, dest; 9471da177e4SLinus Torvalds struct block_device *bdev = s->origin->bdev; 9481da177e4SLinus Torvalds sector_t dev_size; 9491da177e4SLinus Torvalds 9501da177e4SLinus Torvalds dev_size = get_dev_size(bdev); 9511da177e4SLinus Torvalds 9521da177e4SLinus Torvalds src.bdev = bdev; 95371fab00aSJonathan Brassow src.sector = chunk_to_sector(s->store, pe->e.old_chunk); 954d0216849SJonathan Brassow src.count = min(s->store->chunk_size, dev_size - src.sector); 9551da177e4SLinus Torvalds 95649beb2b8SJonathan Brassow dest.bdev = s->store->cow->bdev; 95771fab00aSJonathan Brassow dest.sector = chunk_to_sector(s->store, pe->e.new_chunk); 9581da177e4SLinus Torvalds dest.count = src.count; 9591da177e4SLinus Torvalds 9601da177e4SLinus Torvalds /* Hand over to kcopyd */ 961eb69aca5SHeinz Mauelshagen dm_kcopyd_copy(s->kcopyd_client, 9621da177e4SLinus Torvalds &src, 1, &dest, 0, copy_callback, pe); 9631da177e4SLinus Torvalds } 9641da177e4SLinus Torvalds 9652913808eSMikulas Patocka static struct dm_snap_pending_exception * 9662913808eSMikulas Patocka __lookup_pending_exception(struct dm_snapshot *s, chunk_t chunk) 9672913808eSMikulas Patocka { 9682913808eSMikulas Patocka struct dm_snap_exception *e = lookup_exception(&s->pending, chunk); 9692913808eSMikulas Patocka 9702913808eSMikulas Patocka if (!e) 9712913808eSMikulas Patocka return NULL; 9722913808eSMikulas Patocka 9732913808eSMikulas Patocka return container_of(e, struct dm_snap_pending_exception, e); 9742913808eSMikulas Patocka } 9752913808eSMikulas Patocka 9761da177e4SLinus Torvalds /* 9771da177e4SLinus Torvalds * Looks to see if this snapshot already has a pending exception 9781da177e4SLinus Torvalds * for this chunk, otherwise it allocates a new one and inserts 9791da177e4SLinus Torvalds * it into the pending table. 9801da177e4SLinus Torvalds * 9811da177e4SLinus Torvalds * NOTE: a write lock must be held on snap->lock before calling 9821da177e4SLinus Torvalds * this. 9831da177e4SLinus Torvalds */ 984028867acSAlasdair G Kergon static struct dm_snap_pending_exception * 985c6621392SMikulas Patocka __find_pending_exception(struct dm_snapshot *s, 986c6621392SMikulas Patocka struct dm_snap_pending_exception *pe, chunk_t chunk) 9871da177e4SLinus Torvalds { 988c6621392SMikulas Patocka struct dm_snap_pending_exception *pe2; 98976df1c65SAlasdair G Kergon 9902913808eSMikulas Patocka pe2 = __lookup_pending_exception(s, chunk); 9912913808eSMikulas Patocka if (pe2) { 9921da177e4SLinus Torvalds free_pending_exception(pe); 9932913808eSMikulas Patocka return pe2; 99476df1c65SAlasdair G Kergon } 99576df1c65SAlasdair G Kergon 9961da177e4SLinus Torvalds pe->e.old_chunk = chunk; 9971da177e4SLinus Torvalds bio_list_init(&pe->origin_bios); 9981da177e4SLinus Torvalds bio_list_init(&pe->snapshot_bios); 999b4b610f6SAlasdair G Kergon pe->primary_pe = NULL; 10004b832e8dSAlasdair G Kergon atomic_set(&pe->ref_count, 0); 10011da177e4SLinus Torvalds pe->started = 0; 10021da177e4SLinus Torvalds 1003493df71cSJonathan Brassow if (s->store->type->prepare_exception(s->store, &pe->e)) { 10041da177e4SLinus Torvalds free_pending_exception(pe); 10051da177e4SLinus Torvalds return NULL; 10061da177e4SLinus Torvalds } 10071da177e4SLinus Torvalds 10084b832e8dSAlasdair G Kergon get_pending_exception(pe); 10091da177e4SLinus Torvalds insert_exception(&s->pending, &pe->e); 10101da177e4SLinus Torvalds 10111da177e4SLinus Torvalds return pe; 10121da177e4SLinus Torvalds } 10131da177e4SLinus Torvalds 1014028867acSAlasdair G Kergon static void remap_exception(struct dm_snapshot *s, struct dm_snap_exception *e, 1015d74f81f8SMilan Broz struct bio *bio, chunk_t chunk) 10161da177e4SLinus Torvalds { 101749beb2b8SJonathan Brassow bio->bi_bdev = s->store->cow->bdev; 101871fab00aSJonathan Brassow bio->bi_sector = chunk_to_sector(s->store, 101971fab00aSJonathan Brassow dm_chunk_number(e->new_chunk) + 1020d74f81f8SMilan Broz (chunk - e->old_chunk)) + 102171fab00aSJonathan Brassow (bio->bi_sector & 102271fab00aSJonathan Brassow s->store->chunk_mask); 10231da177e4SLinus Torvalds } 10241da177e4SLinus Torvalds 10251da177e4SLinus Torvalds static int snapshot_map(struct dm_target *ti, struct bio *bio, 10261da177e4SLinus Torvalds union map_info *map_context) 10271da177e4SLinus Torvalds { 1028028867acSAlasdair G Kergon struct dm_snap_exception *e; 1029028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 1030d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED; 10311da177e4SLinus Torvalds chunk_t chunk; 1032028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = NULL; 10331da177e4SLinus Torvalds 1034494b3ee7SMikulas Patocka if (unlikely(bio_empty_barrier(bio))) { 1035494b3ee7SMikulas Patocka bio->bi_bdev = s->store->cow->bdev; 1036494b3ee7SMikulas Patocka return DM_MAPIO_REMAPPED; 1037494b3ee7SMikulas Patocka } 1038494b3ee7SMikulas Patocka 103971fab00aSJonathan Brassow chunk = sector_to_chunk(s->store, bio->bi_sector); 10401da177e4SLinus Torvalds 10411da177e4SLinus Torvalds /* Full snapshots are not usable */ 104276df1c65SAlasdair G Kergon /* To get here the table must be live so s->active is always set. */ 10431da177e4SLinus Torvalds if (!s->valid) 1044f6a80ea8SAlasdair G Kergon return -EIO; 10451da177e4SLinus Torvalds 10461da177e4SLinus Torvalds /* FIXME: should only take write lock if we need 10471da177e4SLinus Torvalds * to copy an exception */ 10481da177e4SLinus Torvalds down_write(&s->lock); 10491da177e4SLinus Torvalds 105076df1c65SAlasdair G Kergon if (!s->valid) { 105176df1c65SAlasdair G Kergon r = -EIO; 105276df1c65SAlasdair G Kergon goto out_unlock; 105376df1c65SAlasdair G Kergon } 105476df1c65SAlasdair G Kergon 10551da177e4SLinus Torvalds /* If the block is already remapped - use that, else remap it */ 10561da177e4SLinus Torvalds e = lookup_exception(&s->complete, chunk); 10571da177e4SLinus Torvalds if (e) { 1058d74f81f8SMilan Broz remap_exception(s, e, bio, chunk); 105976df1c65SAlasdair G Kergon goto out_unlock; 106076df1c65SAlasdair G Kergon } 10611da177e4SLinus Torvalds 1062ba40a2aaSAlasdair G Kergon /* 1063ba40a2aaSAlasdair G Kergon * Write to snapshot - higher level takes care of RW/RO 1064ba40a2aaSAlasdair G Kergon * flags so we should only get this if we are 1065ba40a2aaSAlasdair G Kergon * writeable. 1066ba40a2aaSAlasdair G Kergon */ 1067ba40a2aaSAlasdair G Kergon if (bio_rw(bio) == WRITE) { 10682913808eSMikulas Patocka pe = __lookup_pending_exception(s, chunk); 10692913808eSMikulas Patocka if (!pe) { 1070c6621392SMikulas Patocka up_write(&s->lock); 1071c6621392SMikulas Patocka pe = alloc_pending_exception(s); 1072c6621392SMikulas Patocka down_write(&s->lock); 1073c6621392SMikulas Patocka 1074c6621392SMikulas Patocka if (!s->valid) { 1075c6621392SMikulas Patocka free_pending_exception(pe); 1076c6621392SMikulas Patocka r = -EIO; 1077c6621392SMikulas Patocka goto out_unlock; 1078c6621392SMikulas Patocka } 1079c6621392SMikulas Patocka 108035bf659bSMikulas Patocka e = lookup_exception(&s->complete, chunk); 108135bf659bSMikulas Patocka if (e) { 108235bf659bSMikulas Patocka free_pending_exception(pe); 108335bf659bSMikulas Patocka remap_exception(s, e, bio, chunk); 108435bf659bSMikulas Patocka goto out_unlock; 108535bf659bSMikulas Patocka } 108635bf659bSMikulas Patocka 1087c6621392SMikulas Patocka pe = __find_pending_exception(s, pe, chunk); 10881da177e4SLinus Torvalds if (!pe) { 1089695368acSAlasdair G Kergon __invalidate_snapshot(s, -ENOMEM); 10901da177e4SLinus Torvalds r = -EIO; 109176df1c65SAlasdair G Kergon goto out_unlock; 109276df1c65SAlasdair G Kergon } 10932913808eSMikulas Patocka } 109476df1c65SAlasdair G Kergon 1095d74f81f8SMilan Broz remap_exception(s, &pe->e, bio, chunk); 10961da177e4SLinus Torvalds bio_list_add(&pe->snapshot_bios, bio); 10971da177e4SLinus Torvalds 1098d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 1099ba40a2aaSAlasdair G Kergon 11001da177e4SLinus Torvalds if (!pe->started) { 11011da177e4SLinus Torvalds /* this is protected by snap->lock */ 11021da177e4SLinus Torvalds pe->started = 1; 110376df1c65SAlasdair G Kergon up_write(&s->lock); 110476df1c65SAlasdair G Kergon start_copy(pe); 1105ba40a2aaSAlasdair G Kergon goto out; 1106ba40a2aaSAlasdair G Kergon } 1107cd45daffSMikulas Patocka } else { 11081da177e4SLinus Torvalds bio->bi_bdev = s->origin->bdev; 1109cd45daffSMikulas Patocka map_context->ptr = track_chunk(s, chunk); 1110cd45daffSMikulas Patocka } 11111da177e4SLinus Torvalds 1112ba40a2aaSAlasdair G Kergon out_unlock: 1113ba40a2aaSAlasdair G Kergon up_write(&s->lock); 1114ba40a2aaSAlasdair G Kergon out: 11151da177e4SLinus Torvalds return r; 11161da177e4SLinus Torvalds } 11171da177e4SLinus Torvalds 1118cd45daffSMikulas Patocka static int snapshot_end_io(struct dm_target *ti, struct bio *bio, 1119cd45daffSMikulas Patocka int error, union map_info *map_context) 1120cd45daffSMikulas Patocka { 1121cd45daffSMikulas Patocka struct dm_snapshot *s = ti->private; 1122cd45daffSMikulas Patocka struct dm_snap_tracked_chunk *c = map_context->ptr; 1123cd45daffSMikulas Patocka 1124cd45daffSMikulas Patocka if (c) 1125cd45daffSMikulas Patocka stop_tracking_chunk(s, c); 1126cd45daffSMikulas Patocka 1127cd45daffSMikulas Patocka return 0; 1128cd45daffSMikulas Patocka } 1129cd45daffSMikulas Patocka 11301da177e4SLinus Torvalds static void snapshot_resume(struct dm_target *ti) 11311da177e4SLinus Torvalds { 1132028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 11331da177e4SLinus Torvalds 1134aa14edebSAlasdair G Kergon down_write(&s->lock); 1135aa14edebSAlasdair G Kergon s->active = 1; 1136aa14edebSAlasdair G Kergon up_write(&s->lock); 11371da177e4SLinus Torvalds } 11381da177e4SLinus Torvalds 11391da177e4SLinus Torvalds static int snapshot_status(struct dm_target *ti, status_type_t type, 11401da177e4SLinus Torvalds char *result, unsigned int maxlen) 11411da177e4SLinus Torvalds { 11422e4a31dfSJonathan Brassow unsigned sz = 0; 1143028867acSAlasdair G Kergon struct dm_snapshot *snap = ti->private; 11441da177e4SLinus Torvalds 11451da177e4SLinus Torvalds switch (type) { 11461da177e4SLinus Torvalds case STATUSTYPE_INFO: 11471da177e4SLinus Torvalds if (!snap->valid) 11482e4a31dfSJonathan Brassow DMEMIT("Invalid"); 11491da177e4SLinus Torvalds else { 1150493df71cSJonathan Brassow if (snap->store->type->fraction_full) { 11511da177e4SLinus Torvalds sector_t numerator, denominator; 1152493df71cSJonathan Brassow snap->store->type->fraction_full(snap->store, 11531da177e4SLinus Torvalds &numerator, 11541da177e4SLinus Torvalds &denominator); 11552e4a31dfSJonathan Brassow DMEMIT("%llu/%llu", 11564ee218cdSAndrew Morton (unsigned long long)numerator, 11574ee218cdSAndrew Morton (unsigned long long)denominator); 11581da177e4SLinus Torvalds } 11591da177e4SLinus Torvalds else 11602e4a31dfSJonathan Brassow DMEMIT("Unknown"); 11611da177e4SLinus Torvalds } 11621da177e4SLinus Torvalds break; 11631da177e4SLinus Torvalds 11641da177e4SLinus Torvalds case STATUSTYPE_TABLE: 11651da177e4SLinus Torvalds /* 11661da177e4SLinus Torvalds * kdevname returns a static pointer so we need 11671da177e4SLinus Torvalds * to make private copies if the output is to 11681da177e4SLinus Torvalds * make sense. 11691da177e4SLinus Torvalds */ 11702e4a31dfSJonathan Brassow DMEMIT("%s", snap->origin->name); 11711e302a92SJonathan Brassow snap->store->type->status(snap->store, type, result + sz, 11721e302a92SJonathan Brassow maxlen - sz); 11731da177e4SLinus Torvalds break; 11741da177e4SLinus Torvalds } 11751da177e4SLinus Torvalds 11761da177e4SLinus Torvalds return 0; 11771da177e4SLinus Torvalds } 11781da177e4SLinus Torvalds 11798811f46cSMike Snitzer static int snapshot_iterate_devices(struct dm_target *ti, 11808811f46cSMike Snitzer iterate_devices_callout_fn fn, void *data) 11818811f46cSMike Snitzer { 11828811f46cSMike Snitzer struct dm_snapshot *snap = ti->private; 11838811f46cSMike Snitzer 11848811f46cSMike Snitzer return fn(ti, snap->origin, 0, ti->len, data); 11858811f46cSMike Snitzer } 11868811f46cSMike Snitzer 11878811f46cSMike Snitzer 11881da177e4SLinus Torvalds /*----------------------------------------------------------------- 11891da177e4SLinus Torvalds * Origin methods 11901da177e4SLinus Torvalds *---------------------------------------------------------------*/ 11911da177e4SLinus Torvalds static int __origin_write(struct list_head *snapshots, struct bio *bio) 11921da177e4SLinus Torvalds { 1193d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED, first = 0; 11941da177e4SLinus Torvalds struct dm_snapshot *snap; 1195028867acSAlasdair G Kergon struct dm_snap_exception *e; 1196028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe, *next_pe, *primary_pe = NULL; 11971da177e4SLinus Torvalds chunk_t chunk; 1198eccf0817SAlasdair G Kergon LIST_HEAD(pe_queue); 11991da177e4SLinus Torvalds 12001da177e4SLinus Torvalds /* Do all the snapshots on this origin */ 12011da177e4SLinus Torvalds list_for_each_entry (snap, snapshots, list) { 12021da177e4SLinus Torvalds 120376df1c65SAlasdair G Kergon down_write(&snap->lock); 120476df1c65SAlasdair G Kergon 1205aa14edebSAlasdair G Kergon /* Only deal with valid and active snapshots */ 1206aa14edebSAlasdair G Kergon if (!snap->valid || !snap->active) 120776df1c65SAlasdair G Kergon goto next_snapshot; 12081da177e4SLinus Torvalds 1209d5e404c1SAlasdair G Kergon /* Nothing to do if writing beyond end of snapshot */ 12100cea9c78SJonathan Brassow if (bio->bi_sector >= dm_table_get_size(snap->store->ti->table)) 121176df1c65SAlasdair G Kergon goto next_snapshot; 12121da177e4SLinus Torvalds 12131da177e4SLinus Torvalds /* 12141da177e4SLinus Torvalds * Remember, different snapshots can have 12151da177e4SLinus Torvalds * different chunk sizes. 12161da177e4SLinus Torvalds */ 121771fab00aSJonathan Brassow chunk = sector_to_chunk(snap->store, bio->bi_sector); 12181da177e4SLinus Torvalds 12191da177e4SLinus Torvalds /* 12201da177e4SLinus Torvalds * Check exception table to see if block 12211da177e4SLinus Torvalds * is already remapped in this snapshot 12221da177e4SLinus Torvalds * and trigger an exception if not. 1223b4b610f6SAlasdair G Kergon * 12244b832e8dSAlasdair G Kergon * ref_count is initialised to 1 so pending_complete() 1225b4b610f6SAlasdair G Kergon * won't destroy the primary_pe while we're inside this loop. 12261da177e4SLinus Torvalds */ 12271da177e4SLinus Torvalds e = lookup_exception(&snap->complete, chunk); 122876df1c65SAlasdair G Kergon if (e) 122976df1c65SAlasdair G Kergon goto next_snapshot; 123076df1c65SAlasdair G Kergon 12312913808eSMikulas Patocka pe = __lookup_pending_exception(snap, chunk); 12322913808eSMikulas Patocka if (!pe) { 1233c6621392SMikulas Patocka up_write(&snap->lock); 1234c6621392SMikulas Patocka pe = alloc_pending_exception(snap); 1235c6621392SMikulas Patocka down_write(&snap->lock); 1236c6621392SMikulas Patocka 1237c6621392SMikulas Patocka if (!snap->valid) { 1238c6621392SMikulas Patocka free_pending_exception(pe); 1239c6621392SMikulas Patocka goto next_snapshot; 1240c6621392SMikulas Patocka } 1241c6621392SMikulas Patocka 124235bf659bSMikulas Patocka e = lookup_exception(&snap->complete, chunk); 124335bf659bSMikulas Patocka if (e) { 124435bf659bSMikulas Patocka free_pending_exception(pe); 124535bf659bSMikulas Patocka goto next_snapshot; 124635bf659bSMikulas Patocka } 124735bf659bSMikulas Patocka 1248c6621392SMikulas Patocka pe = __find_pending_exception(snap, pe, chunk); 12491da177e4SLinus Torvalds if (!pe) { 1250695368acSAlasdair G Kergon __invalidate_snapshot(snap, -ENOMEM); 125176df1c65SAlasdair G Kergon goto next_snapshot; 125276df1c65SAlasdair G Kergon } 12532913808eSMikulas Patocka } 12541da177e4SLinus Torvalds 1255b4b610f6SAlasdair G Kergon if (!primary_pe) { 1256b4b610f6SAlasdair G Kergon /* 1257b4b610f6SAlasdair G Kergon * Either every pe here has same 1258b4b610f6SAlasdair G Kergon * primary_pe or none has one yet. 1259b4b610f6SAlasdair G Kergon */ 1260b4b610f6SAlasdair G Kergon if (pe->primary_pe) 1261b4b610f6SAlasdair G Kergon primary_pe = pe->primary_pe; 1262b4b610f6SAlasdair G Kergon else { 1263b4b610f6SAlasdair G Kergon primary_pe = pe; 1264b4b610f6SAlasdair G Kergon first = 1; 1265eccf0817SAlasdair G Kergon } 1266b4b610f6SAlasdair G Kergon 126776df1c65SAlasdair G Kergon bio_list_add(&primary_pe->origin_bios, bio); 126876df1c65SAlasdair G Kergon 1269d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 1270b4b610f6SAlasdair G Kergon } 127176df1c65SAlasdair G Kergon 1272b4b610f6SAlasdair G Kergon if (!pe->primary_pe) { 1273b4b610f6SAlasdair G Kergon pe->primary_pe = primary_pe; 12744b832e8dSAlasdair G Kergon get_pending_exception(primary_pe); 1275b4b610f6SAlasdair G Kergon } 127676df1c65SAlasdair G Kergon 1277eccf0817SAlasdair G Kergon if (!pe->started) { 1278eccf0817SAlasdair G Kergon pe->started = 1; 1279eccf0817SAlasdair G Kergon list_add_tail(&pe->list, &pe_queue); 1280eccf0817SAlasdair G Kergon } 12811da177e4SLinus Torvalds 128276df1c65SAlasdair G Kergon next_snapshot: 12831da177e4SLinus Torvalds up_write(&snap->lock); 12841da177e4SLinus Torvalds } 12851da177e4SLinus Torvalds 1286b4b610f6SAlasdair G Kergon if (!primary_pe) 12874b832e8dSAlasdair G Kergon return r; 1288b4b610f6SAlasdair G Kergon 1289b4b610f6SAlasdair G Kergon /* 1290b4b610f6SAlasdair G Kergon * If this is the first time we're processing this chunk and 12914b832e8dSAlasdair G Kergon * ref_count is now 1 it means all the pending exceptions 1292b4b610f6SAlasdair G Kergon * got completed while we were in the loop above, so it falls to 1293b4b610f6SAlasdair G Kergon * us here to remove the primary_pe and submit any origin_bios. 1294b4b610f6SAlasdair G Kergon */ 1295b4b610f6SAlasdair G Kergon 12964b832e8dSAlasdair G Kergon if (first && atomic_dec_and_test(&primary_pe->ref_count)) { 1297b4b610f6SAlasdair G Kergon flush_bios(bio_list_get(&primary_pe->origin_bios)); 1298b4b610f6SAlasdair G Kergon free_pending_exception(primary_pe); 1299b4b610f6SAlasdair G Kergon /* If we got here, pe_queue is necessarily empty. */ 13004b832e8dSAlasdair G Kergon return r; 1301b4b610f6SAlasdair G Kergon } 1302b4b610f6SAlasdair G Kergon 13031da177e4SLinus Torvalds /* 13041da177e4SLinus Torvalds * Now that we have a complete pe list we can start the copying. 13051da177e4SLinus Torvalds */ 1306eccf0817SAlasdair G Kergon list_for_each_entry_safe(pe, next_pe, &pe_queue, list) 13071da177e4SLinus Torvalds start_copy(pe); 13081da177e4SLinus Torvalds 13091da177e4SLinus Torvalds return r; 13101da177e4SLinus Torvalds } 13111da177e4SLinus Torvalds 13121da177e4SLinus Torvalds /* 13131da177e4SLinus Torvalds * Called on a write from the origin driver. 13141da177e4SLinus Torvalds */ 13151da177e4SLinus Torvalds static int do_origin(struct dm_dev *origin, struct bio *bio) 13161da177e4SLinus Torvalds { 13171da177e4SLinus Torvalds struct origin *o; 1318d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED; 13191da177e4SLinus Torvalds 13201da177e4SLinus Torvalds down_read(&_origins_lock); 13211da177e4SLinus Torvalds o = __lookup_origin(origin->bdev); 13221da177e4SLinus Torvalds if (o) 13231da177e4SLinus Torvalds r = __origin_write(&o->snapshots, bio); 13241da177e4SLinus Torvalds up_read(&_origins_lock); 13251da177e4SLinus Torvalds 13261da177e4SLinus Torvalds return r; 13271da177e4SLinus Torvalds } 13281da177e4SLinus Torvalds 13291da177e4SLinus Torvalds /* 13301da177e4SLinus Torvalds * Origin: maps a linear range of a device, with hooks for snapshotting. 13311da177e4SLinus Torvalds */ 13321da177e4SLinus Torvalds 13331da177e4SLinus Torvalds /* 13341da177e4SLinus Torvalds * Construct an origin mapping: <dev_path> 13351da177e4SLinus Torvalds * The context for an origin is merely a 'struct dm_dev *' 13361da177e4SLinus Torvalds * pointing to the real device. 13371da177e4SLinus Torvalds */ 13381da177e4SLinus Torvalds static int origin_ctr(struct dm_target *ti, unsigned int argc, char **argv) 13391da177e4SLinus Torvalds { 13401da177e4SLinus Torvalds int r; 13411da177e4SLinus Torvalds struct dm_dev *dev; 13421da177e4SLinus Torvalds 13431da177e4SLinus Torvalds if (argc != 1) { 134472d94861SAlasdair G Kergon ti->error = "origin: incorrect number of arguments"; 13451da177e4SLinus Torvalds return -EINVAL; 13461da177e4SLinus Torvalds } 13471da177e4SLinus Torvalds 13481da177e4SLinus Torvalds r = dm_get_device(ti, argv[0], 0, ti->len, 13491da177e4SLinus Torvalds dm_table_get_mode(ti->table), &dev); 13501da177e4SLinus Torvalds if (r) { 13511da177e4SLinus Torvalds ti->error = "Cannot get target device"; 13521da177e4SLinus Torvalds return r; 13531da177e4SLinus Torvalds } 13541da177e4SLinus Torvalds 13551da177e4SLinus Torvalds ti->private = dev; 1356494b3ee7SMikulas Patocka ti->num_flush_requests = 1; 1357494b3ee7SMikulas Patocka 13581da177e4SLinus Torvalds return 0; 13591da177e4SLinus Torvalds } 13601da177e4SLinus Torvalds 13611da177e4SLinus Torvalds static void origin_dtr(struct dm_target *ti) 13621da177e4SLinus Torvalds { 1363028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 13641da177e4SLinus Torvalds dm_put_device(ti, dev); 13651da177e4SLinus Torvalds } 13661da177e4SLinus Torvalds 13671da177e4SLinus Torvalds static int origin_map(struct dm_target *ti, struct bio *bio, 13681da177e4SLinus Torvalds union map_info *map_context) 13691da177e4SLinus Torvalds { 1370028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 13711da177e4SLinus Torvalds bio->bi_bdev = dev->bdev; 13721da177e4SLinus Torvalds 1373494b3ee7SMikulas Patocka if (unlikely(bio_empty_barrier(bio))) 1374494b3ee7SMikulas Patocka return DM_MAPIO_REMAPPED; 1375494b3ee7SMikulas Patocka 13761da177e4SLinus Torvalds /* Only tell snapshots if this is a write */ 1377d2a7ad29SKiyoshi Ueda return (bio_rw(bio) == WRITE) ? do_origin(dev, bio) : DM_MAPIO_REMAPPED; 13781da177e4SLinus Torvalds } 13791da177e4SLinus Torvalds 13801da177e4SLinus Torvalds #define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r)) 13811da177e4SLinus Torvalds 13821da177e4SLinus Torvalds /* 13831da177e4SLinus Torvalds * Set the target "split_io" field to the minimum of all the snapshots' 13841da177e4SLinus Torvalds * chunk sizes. 13851da177e4SLinus Torvalds */ 13861da177e4SLinus Torvalds static void origin_resume(struct dm_target *ti) 13871da177e4SLinus Torvalds { 1388028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 13891da177e4SLinus Torvalds struct dm_snapshot *snap; 13901da177e4SLinus Torvalds struct origin *o; 13911da177e4SLinus Torvalds chunk_t chunk_size = 0; 13921da177e4SLinus Torvalds 13931da177e4SLinus Torvalds down_read(&_origins_lock); 13941da177e4SLinus Torvalds o = __lookup_origin(dev->bdev); 13951da177e4SLinus Torvalds if (o) 13961da177e4SLinus Torvalds list_for_each_entry (snap, &o->snapshots, list) 1397d0216849SJonathan Brassow chunk_size = min_not_zero(chunk_size, 1398d0216849SJonathan Brassow snap->store->chunk_size); 13991da177e4SLinus Torvalds up_read(&_origins_lock); 14001da177e4SLinus Torvalds 14011da177e4SLinus Torvalds ti->split_io = chunk_size; 14021da177e4SLinus Torvalds } 14031da177e4SLinus Torvalds 14041da177e4SLinus Torvalds static int origin_status(struct dm_target *ti, status_type_t type, char *result, 14051da177e4SLinus Torvalds unsigned int maxlen) 14061da177e4SLinus Torvalds { 1407028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 14081da177e4SLinus Torvalds 14091da177e4SLinus Torvalds switch (type) { 14101da177e4SLinus Torvalds case STATUSTYPE_INFO: 14111da177e4SLinus Torvalds result[0] = '\0'; 14121da177e4SLinus Torvalds break; 14131da177e4SLinus Torvalds 14141da177e4SLinus Torvalds case STATUSTYPE_TABLE: 14151da177e4SLinus Torvalds snprintf(result, maxlen, "%s", dev->name); 14161da177e4SLinus Torvalds break; 14171da177e4SLinus Torvalds } 14181da177e4SLinus Torvalds 14191da177e4SLinus Torvalds return 0; 14201da177e4SLinus Torvalds } 14211da177e4SLinus Torvalds 14228811f46cSMike Snitzer static int origin_iterate_devices(struct dm_target *ti, 14238811f46cSMike Snitzer iterate_devices_callout_fn fn, void *data) 14248811f46cSMike Snitzer { 14258811f46cSMike Snitzer struct dm_dev *dev = ti->private; 14268811f46cSMike Snitzer 14278811f46cSMike Snitzer return fn(ti, dev, 0, ti->len, data); 14288811f46cSMike Snitzer } 14298811f46cSMike Snitzer 14301da177e4SLinus Torvalds static struct target_type origin_target = { 14311da177e4SLinus Torvalds .name = "snapshot-origin", 14328811f46cSMike Snitzer .version = {1, 7, 0}, 14331da177e4SLinus Torvalds .module = THIS_MODULE, 14341da177e4SLinus Torvalds .ctr = origin_ctr, 14351da177e4SLinus Torvalds .dtr = origin_dtr, 14361da177e4SLinus Torvalds .map = origin_map, 14371da177e4SLinus Torvalds .resume = origin_resume, 14381da177e4SLinus Torvalds .status = origin_status, 14398811f46cSMike Snitzer .iterate_devices = origin_iterate_devices, 14401da177e4SLinus Torvalds }; 14411da177e4SLinus Torvalds 14421da177e4SLinus Torvalds static struct target_type snapshot_target = { 14431da177e4SLinus Torvalds .name = "snapshot", 14448811f46cSMike Snitzer .version = {1, 7, 0}, 14451da177e4SLinus Torvalds .module = THIS_MODULE, 14461da177e4SLinus Torvalds .ctr = snapshot_ctr, 14471da177e4SLinus Torvalds .dtr = snapshot_dtr, 14481da177e4SLinus Torvalds .map = snapshot_map, 1449cd45daffSMikulas Patocka .end_io = snapshot_end_io, 14501da177e4SLinus Torvalds .resume = snapshot_resume, 14511da177e4SLinus Torvalds .status = snapshot_status, 14528811f46cSMike Snitzer .iterate_devices = snapshot_iterate_devices, 14531da177e4SLinus Torvalds }; 14541da177e4SLinus Torvalds 14551da177e4SLinus Torvalds static int __init dm_snapshot_init(void) 14561da177e4SLinus Torvalds { 14571da177e4SLinus Torvalds int r; 14581da177e4SLinus Torvalds 14594db6bfe0SAlasdair G Kergon r = dm_exception_store_init(); 14604db6bfe0SAlasdair G Kergon if (r) { 14614db6bfe0SAlasdair G Kergon DMERR("Failed to initialize exception stores"); 14624db6bfe0SAlasdair G Kergon return r; 14634db6bfe0SAlasdair G Kergon } 14644db6bfe0SAlasdair G Kergon 14651da177e4SLinus Torvalds r = dm_register_target(&snapshot_target); 14661da177e4SLinus Torvalds if (r) { 14671da177e4SLinus Torvalds DMERR("snapshot target register failed %d", r); 14681da177e4SLinus Torvalds return r; 14691da177e4SLinus Torvalds } 14701da177e4SLinus Torvalds 14711da177e4SLinus Torvalds r = dm_register_target(&origin_target); 14721da177e4SLinus Torvalds if (r < 0) { 147372d94861SAlasdair G Kergon DMERR("Origin target register failed %d", r); 14741da177e4SLinus Torvalds goto bad1; 14751da177e4SLinus Torvalds } 14761da177e4SLinus Torvalds 14771da177e4SLinus Torvalds r = init_origin_hash(); 14781da177e4SLinus Torvalds if (r) { 14791da177e4SLinus Torvalds DMERR("init_origin_hash failed."); 14801da177e4SLinus Torvalds goto bad2; 14811da177e4SLinus Torvalds } 14821da177e4SLinus Torvalds 1483028867acSAlasdair G Kergon exception_cache = KMEM_CACHE(dm_snap_exception, 0); 14841da177e4SLinus Torvalds if (!exception_cache) { 14851da177e4SLinus Torvalds DMERR("Couldn't create exception cache."); 14861da177e4SLinus Torvalds r = -ENOMEM; 14871da177e4SLinus Torvalds goto bad3; 14881da177e4SLinus Torvalds } 14891da177e4SLinus Torvalds 1490028867acSAlasdair G Kergon pending_cache = KMEM_CACHE(dm_snap_pending_exception, 0); 14911da177e4SLinus Torvalds if (!pending_cache) { 14921da177e4SLinus Torvalds DMERR("Couldn't create pending cache."); 14931da177e4SLinus Torvalds r = -ENOMEM; 14941da177e4SLinus Torvalds goto bad4; 14951da177e4SLinus Torvalds } 14961da177e4SLinus Torvalds 1497cd45daffSMikulas Patocka tracked_chunk_cache = KMEM_CACHE(dm_snap_tracked_chunk, 0); 1498cd45daffSMikulas Patocka if (!tracked_chunk_cache) { 1499cd45daffSMikulas Patocka DMERR("Couldn't create cache to track chunks in use."); 1500cd45daffSMikulas Patocka r = -ENOMEM; 1501cd45daffSMikulas Patocka goto bad5; 1502cd45daffSMikulas Patocka } 1503cd45daffSMikulas Patocka 1504ca3a931fSAlasdair G Kergon ksnapd = create_singlethread_workqueue("ksnapd"); 1505ca3a931fSAlasdair G Kergon if (!ksnapd) { 1506ca3a931fSAlasdair G Kergon DMERR("Failed to create ksnapd workqueue."); 1507ca3a931fSAlasdair G Kergon r = -ENOMEM; 150892e86812SMikulas Patocka goto bad_pending_pool; 1509ca3a931fSAlasdair G Kergon } 1510ca3a931fSAlasdair G Kergon 15111da177e4SLinus Torvalds return 0; 15121da177e4SLinus Torvalds 1513cd45daffSMikulas Patocka bad_pending_pool: 1514cd45daffSMikulas Patocka kmem_cache_destroy(tracked_chunk_cache); 15151da177e4SLinus Torvalds bad5: 15161da177e4SLinus Torvalds kmem_cache_destroy(pending_cache); 15171da177e4SLinus Torvalds bad4: 15181da177e4SLinus Torvalds kmem_cache_destroy(exception_cache); 15191da177e4SLinus Torvalds bad3: 15201da177e4SLinus Torvalds exit_origin_hash(); 15211da177e4SLinus Torvalds bad2: 15221da177e4SLinus Torvalds dm_unregister_target(&origin_target); 15231da177e4SLinus Torvalds bad1: 15241da177e4SLinus Torvalds dm_unregister_target(&snapshot_target); 15251da177e4SLinus Torvalds return r; 15261da177e4SLinus Torvalds } 15271da177e4SLinus Torvalds 15281da177e4SLinus Torvalds static void __exit dm_snapshot_exit(void) 15291da177e4SLinus Torvalds { 1530ca3a931fSAlasdair G Kergon destroy_workqueue(ksnapd); 1531ca3a931fSAlasdair G Kergon 153210d3bd09SMikulas Patocka dm_unregister_target(&snapshot_target); 153310d3bd09SMikulas Patocka dm_unregister_target(&origin_target); 15341da177e4SLinus Torvalds 15351da177e4SLinus Torvalds exit_origin_hash(); 15361da177e4SLinus Torvalds kmem_cache_destroy(pending_cache); 15371da177e4SLinus Torvalds kmem_cache_destroy(exception_cache); 1538cd45daffSMikulas Patocka kmem_cache_destroy(tracked_chunk_cache); 15394db6bfe0SAlasdair G Kergon 15404db6bfe0SAlasdair G Kergon dm_exception_store_exit(); 15411da177e4SLinus Torvalds } 15421da177e4SLinus Torvalds 15431da177e4SLinus Torvalds /* Module hooks */ 15441da177e4SLinus Torvalds module_init(dm_snapshot_init); 15451da177e4SLinus Torvalds module_exit(dm_snapshot_exit); 15461da177e4SLinus Torvalds 15471da177e4SLinus Torvalds MODULE_DESCRIPTION(DM_NAME " snapshot target"); 15481da177e4SLinus Torvalds MODULE_AUTHOR("Joe Thornber"); 15491da177e4SLinus Torvalds MODULE_LICENSE("GPL"); 1550