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 #include "dm-bio-list.h" 261da177e4SLinus Torvalds 2772d94861SAlasdair G Kergon #define DM_MSG_PREFIX "snapshots" 2872d94861SAlasdair G Kergon 291da177e4SLinus Torvalds /* 301da177e4SLinus Torvalds * The percentage increment we will wake up users at 311da177e4SLinus Torvalds */ 321da177e4SLinus Torvalds #define WAKE_UP_PERCENT 5 331da177e4SLinus Torvalds 341da177e4SLinus Torvalds /* 351da177e4SLinus Torvalds * kcopyd priority of snapshot operations 361da177e4SLinus Torvalds */ 371da177e4SLinus Torvalds #define SNAPSHOT_COPY_PRIORITY 2 381da177e4SLinus Torvalds 391da177e4SLinus Torvalds /* 408ee2767aSMilan Broz * Reserve 1MB for each snapshot initially (with minimum of 1 page). 411da177e4SLinus Torvalds */ 428ee2767aSMilan Broz #define SNAPSHOT_PAGES (((1UL << 20) >> PAGE_SHIFT) ? : 1) 431da177e4SLinus Torvalds 44cd45daffSMikulas Patocka /* 45cd45daffSMikulas Patocka * The size of the mempool used to track chunks in use. 46cd45daffSMikulas Patocka */ 47cd45daffSMikulas Patocka #define MIN_IOS 256 48cd45daffSMikulas Patocka 49ccc45ea8SJonathan Brassow #define DM_TRACKED_CHUNK_HASH_SIZE 16 50ccc45ea8SJonathan Brassow #define DM_TRACKED_CHUNK_HASH(x) ((unsigned long)(x) & \ 51ccc45ea8SJonathan Brassow (DM_TRACKED_CHUNK_HASH_SIZE - 1)) 52ccc45ea8SJonathan Brassow 53ccc45ea8SJonathan Brassow struct exception_table { 54ccc45ea8SJonathan Brassow uint32_t hash_mask; 55ccc45ea8SJonathan Brassow unsigned hash_shift; 56ccc45ea8SJonathan Brassow struct list_head *table; 57ccc45ea8SJonathan Brassow }; 58ccc45ea8SJonathan Brassow 59ccc45ea8SJonathan Brassow struct dm_snapshot { 60ccc45ea8SJonathan Brassow struct rw_semaphore lock; 61ccc45ea8SJonathan Brassow 62ccc45ea8SJonathan Brassow struct dm_dev *origin; 63ccc45ea8SJonathan Brassow 64ccc45ea8SJonathan Brassow /* List of snapshots per Origin */ 65ccc45ea8SJonathan Brassow struct list_head list; 66ccc45ea8SJonathan Brassow 67ccc45ea8SJonathan Brassow /* You can't use a snapshot if this is 0 (e.g. if full) */ 68ccc45ea8SJonathan Brassow int valid; 69ccc45ea8SJonathan Brassow 70ccc45ea8SJonathan Brassow /* Origin writes don't trigger exceptions until this is set */ 71ccc45ea8SJonathan Brassow int active; 72ccc45ea8SJonathan Brassow 73ccc45ea8SJonathan Brassow mempool_t *pending_pool; 74ccc45ea8SJonathan Brassow 75ccc45ea8SJonathan Brassow atomic_t pending_exceptions_count; 76ccc45ea8SJonathan Brassow 77ccc45ea8SJonathan Brassow struct exception_table pending; 78ccc45ea8SJonathan Brassow struct exception_table complete; 79ccc45ea8SJonathan Brassow 80ccc45ea8SJonathan Brassow /* 81ccc45ea8SJonathan Brassow * pe_lock protects all pending_exception operations and access 82ccc45ea8SJonathan Brassow * as well as the snapshot_bios list. 83ccc45ea8SJonathan Brassow */ 84ccc45ea8SJonathan Brassow spinlock_t pe_lock; 85ccc45ea8SJonathan Brassow 86ccc45ea8SJonathan Brassow /* The on disk metadata handler */ 87ccc45ea8SJonathan Brassow struct dm_exception_store *store; 88ccc45ea8SJonathan Brassow 89ccc45ea8SJonathan Brassow struct dm_kcopyd_client *kcopyd_client; 90ccc45ea8SJonathan Brassow 91ccc45ea8SJonathan Brassow /* Queue of snapshot writes for ksnapd to flush */ 92ccc45ea8SJonathan Brassow struct bio_list queued_bios; 93ccc45ea8SJonathan Brassow struct work_struct queued_bios_work; 94ccc45ea8SJonathan Brassow 95ccc45ea8SJonathan Brassow /* Chunks with outstanding reads */ 96ccc45ea8SJonathan Brassow mempool_t *tracked_chunk_pool; 97ccc45ea8SJonathan Brassow spinlock_t tracked_chunk_lock; 98ccc45ea8SJonathan Brassow struct hlist_head tracked_chunk_hash[DM_TRACKED_CHUNK_HASH_SIZE]; 99ccc45ea8SJonathan Brassow }; 100ccc45ea8SJonathan Brassow 101c642f9e0SAdrian Bunk static struct workqueue_struct *ksnapd; 102c4028958SDavid Howells static void flush_queued_bios(struct work_struct *work); 103ca3a931fSAlasdair G Kergon 104ccc45ea8SJonathan Brassow static sector_t chunk_to_sector(struct dm_exception_store *store, 105ccc45ea8SJonathan Brassow chunk_t chunk) 106ccc45ea8SJonathan Brassow { 107ccc45ea8SJonathan Brassow return chunk << store->chunk_shift; 108ccc45ea8SJonathan Brassow } 109ccc45ea8SJonathan Brassow 110ccc45ea8SJonathan Brassow static int bdev_equal(struct block_device *lhs, struct block_device *rhs) 111ccc45ea8SJonathan Brassow { 112ccc45ea8SJonathan Brassow /* 113ccc45ea8SJonathan Brassow * There is only ever one instance of a particular block 114ccc45ea8SJonathan Brassow * device so we can compare pointers safely. 115ccc45ea8SJonathan Brassow */ 116ccc45ea8SJonathan Brassow return lhs == rhs; 117ccc45ea8SJonathan Brassow } 118ccc45ea8SJonathan Brassow 119028867acSAlasdair G Kergon struct dm_snap_pending_exception { 120028867acSAlasdair G Kergon struct dm_snap_exception e; 1211da177e4SLinus Torvalds 1221da177e4SLinus Torvalds /* 1231da177e4SLinus Torvalds * Origin buffers waiting for this to complete are held 1241da177e4SLinus Torvalds * in a bio list 1251da177e4SLinus Torvalds */ 1261da177e4SLinus Torvalds struct bio_list origin_bios; 1271da177e4SLinus Torvalds struct bio_list snapshot_bios; 1281da177e4SLinus Torvalds 1291da177e4SLinus Torvalds /* 130eccf0817SAlasdair G Kergon * Short-term queue of pending exceptions prior to submission. 131eccf0817SAlasdair G Kergon */ 132eccf0817SAlasdair G Kergon struct list_head list; 133eccf0817SAlasdair G Kergon 134eccf0817SAlasdair G Kergon /* 135b4b610f6SAlasdair G Kergon * The primary pending_exception is the one that holds 1364b832e8dSAlasdair G Kergon * the ref_count and the list of origin_bios for a 137b4b610f6SAlasdair G Kergon * group of pending_exceptions. It is always last to get freed. 138b4b610f6SAlasdair G Kergon * These fields get set up when writing to the origin. 1391da177e4SLinus Torvalds */ 140028867acSAlasdair G Kergon struct dm_snap_pending_exception *primary_pe; 141b4b610f6SAlasdair G Kergon 142b4b610f6SAlasdair G Kergon /* 143b4b610f6SAlasdair G Kergon * Number of pending_exceptions processing this chunk. 144b4b610f6SAlasdair G Kergon * When this drops to zero we must complete the origin bios. 145b4b610f6SAlasdair G Kergon * If incrementing or decrementing this, hold pe->snap->lock for 146b4b610f6SAlasdair G Kergon * the sibling concerned and not pe->primary_pe->snap->lock unless 147b4b610f6SAlasdair G Kergon * they are the same. 148b4b610f6SAlasdair G Kergon */ 1494b832e8dSAlasdair G Kergon atomic_t ref_count; 1501da177e4SLinus Torvalds 1511da177e4SLinus Torvalds /* Pointer back to snapshot context */ 1521da177e4SLinus Torvalds struct dm_snapshot *snap; 1531da177e4SLinus Torvalds 1541da177e4SLinus Torvalds /* 1551da177e4SLinus Torvalds * 1 indicates the exception has already been sent to 1561da177e4SLinus Torvalds * kcopyd. 1571da177e4SLinus Torvalds */ 1581da177e4SLinus Torvalds int started; 1591da177e4SLinus Torvalds }; 1601da177e4SLinus Torvalds 1611da177e4SLinus Torvalds /* 1621da177e4SLinus Torvalds * Hash table mapping origin volumes to lists of snapshots and 1631da177e4SLinus Torvalds * a lock to protect it 1641da177e4SLinus Torvalds */ 165e18b890bSChristoph Lameter static struct kmem_cache *exception_cache; 166e18b890bSChristoph Lameter static struct kmem_cache *pending_cache; 1671da177e4SLinus Torvalds 168cd45daffSMikulas Patocka struct dm_snap_tracked_chunk { 169cd45daffSMikulas Patocka struct hlist_node node; 170cd45daffSMikulas Patocka chunk_t chunk; 171cd45daffSMikulas Patocka }; 172cd45daffSMikulas Patocka 173cd45daffSMikulas Patocka static struct kmem_cache *tracked_chunk_cache; 174cd45daffSMikulas Patocka 175cd45daffSMikulas Patocka static struct dm_snap_tracked_chunk *track_chunk(struct dm_snapshot *s, 176cd45daffSMikulas Patocka chunk_t chunk) 177cd45daffSMikulas Patocka { 178cd45daffSMikulas Patocka struct dm_snap_tracked_chunk *c = mempool_alloc(s->tracked_chunk_pool, 179cd45daffSMikulas Patocka GFP_NOIO); 180cd45daffSMikulas Patocka unsigned long flags; 181cd45daffSMikulas Patocka 182cd45daffSMikulas Patocka c->chunk = chunk; 183cd45daffSMikulas Patocka 184cd45daffSMikulas Patocka spin_lock_irqsave(&s->tracked_chunk_lock, flags); 185cd45daffSMikulas Patocka hlist_add_head(&c->node, 186cd45daffSMikulas Patocka &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)]); 187cd45daffSMikulas Patocka spin_unlock_irqrestore(&s->tracked_chunk_lock, flags); 188cd45daffSMikulas Patocka 189cd45daffSMikulas Patocka return c; 190cd45daffSMikulas Patocka } 191cd45daffSMikulas Patocka 192cd45daffSMikulas Patocka static void stop_tracking_chunk(struct dm_snapshot *s, 193cd45daffSMikulas Patocka struct dm_snap_tracked_chunk *c) 194cd45daffSMikulas Patocka { 195cd45daffSMikulas Patocka unsigned long flags; 196cd45daffSMikulas Patocka 197cd45daffSMikulas Patocka spin_lock_irqsave(&s->tracked_chunk_lock, flags); 198cd45daffSMikulas Patocka hlist_del(&c->node); 199cd45daffSMikulas Patocka spin_unlock_irqrestore(&s->tracked_chunk_lock, flags); 200cd45daffSMikulas Patocka 201cd45daffSMikulas Patocka mempool_free(c, s->tracked_chunk_pool); 202cd45daffSMikulas Patocka } 203cd45daffSMikulas Patocka 204a8d41b59SMikulas Patocka static int __chunk_is_tracked(struct dm_snapshot *s, chunk_t chunk) 205a8d41b59SMikulas Patocka { 206a8d41b59SMikulas Patocka struct dm_snap_tracked_chunk *c; 207a8d41b59SMikulas Patocka struct hlist_node *hn; 208a8d41b59SMikulas Patocka int found = 0; 209a8d41b59SMikulas Patocka 210a8d41b59SMikulas Patocka spin_lock_irq(&s->tracked_chunk_lock); 211a8d41b59SMikulas Patocka 212a8d41b59SMikulas Patocka hlist_for_each_entry(c, hn, 213a8d41b59SMikulas Patocka &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)], node) { 214a8d41b59SMikulas Patocka if (c->chunk == chunk) { 215a8d41b59SMikulas Patocka found = 1; 216a8d41b59SMikulas Patocka break; 217a8d41b59SMikulas Patocka } 218a8d41b59SMikulas Patocka } 219a8d41b59SMikulas Patocka 220a8d41b59SMikulas Patocka spin_unlock_irq(&s->tracked_chunk_lock); 221a8d41b59SMikulas Patocka 222a8d41b59SMikulas Patocka return found; 223a8d41b59SMikulas Patocka } 224a8d41b59SMikulas Patocka 2251da177e4SLinus Torvalds /* 2261da177e4SLinus Torvalds * One of these per registered origin, held in the snapshot_origins hash 2271da177e4SLinus Torvalds */ 2281da177e4SLinus Torvalds struct origin { 2291da177e4SLinus Torvalds /* The origin device */ 2301da177e4SLinus Torvalds struct block_device *bdev; 2311da177e4SLinus Torvalds 2321da177e4SLinus Torvalds struct list_head hash_list; 2331da177e4SLinus Torvalds 2341da177e4SLinus Torvalds /* List of snapshots for this origin */ 2351da177e4SLinus Torvalds struct list_head snapshots; 2361da177e4SLinus Torvalds }; 2371da177e4SLinus Torvalds 2381da177e4SLinus Torvalds /* 2391da177e4SLinus Torvalds * Size of the hash table for origin volumes. If we make this 2401da177e4SLinus Torvalds * the size of the minors list then it should be nearly perfect 2411da177e4SLinus Torvalds */ 2421da177e4SLinus Torvalds #define ORIGIN_HASH_SIZE 256 2431da177e4SLinus Torvalds #define ORIGIN_MASK 0xFF 2441da177e4SLinus Torvalds static struct list_head *_origins; 2451da177e4SLinus Torvalds static struct rw_semaphore _origins_lock; 2461da177e4SLinus Torvalds 2471da177e4SLinus Torvalds static int init_origin_hash(void) 2481da177e4SLinus Torvalds { 2491da177e4SLinus Torvalds int i; 2501da177e4SLinus Torvalds 2511da177e4SLinus Torvalds _origins = kmalloc(ORIGIN_HASH_SIZE * sizeof(struct list_head), 2521da177e4SLinus Torvalds GFP_KERNEL); 2531da177e4SLinus Torvalds if (!_origins) { 25472d94861SAlasdair G Kergon DMERR("unable to allocate memory"); 2551da177e4SLinus Torvalds return -ENOMEM; 2561da177e4SLinus Torvalds } 2571da177e4SLinus Torvalds 2581da177e4SLinus Torvalds for (i = 0; i < ORIGIN_HASH_SIZE; i++) 2591da177e4SLinus Torvalds INIT_LIST_HEAD(_origins + i); 2601da177e4SLinus Torvalds init_rwsem(&_origins_lock); 2611da177e4SLinus Torvalds 2621da177e4SLinus Torvalds return 0; 2631da177e4SLinus Torvalds } 2641da177e4SLinus Torvalds 2651da177e4SLinus Torvalds static void exit_origin_hash(void) 2661da177e4SLinus Torvalds { 2671da177e4SLinus Torvalds kfree(_origins); 2681da177e4SLinus Torvalds } 2691da177e4SLinus Torvalds 270028867acSAlasdair G Kergon static unsigned origin_hash(struct block_device *bdev) 2711da177e4SLinus Torvalds { 2721da177e4SLinus Torvalds return bdev->bd_dev & ORIGIN_MASK; 2731da177e4SLinus Torvalds } 2741da177e4SLinus Torvalds 2751da177e4SLinus Torvalds static struct origin *__lookup_origin(struct block_device *origin) 2761da177e4SLinus Torvalds { 2771da177e4SLinus Torvalds struct list_head *ol; 2781da177e4SLinus Torvalds struct origin *o; 2791da177e4SLinus Torvalds 2801da177e4SLinus Torvalds ol = &_origins[origin_hash(origin)]; 2811da177e4SLinus Torvalds list_for_each_entry (o, ol, hash_list) 2821da177e4SLinus Torvalds if (bdev_equal(o->bdev, origin)) 2831da177e4SLinus Torvalds return o; 2841da177e4SLinus Torvalds 2851da177e4SLinus Torvalds return NULL; 2861da177e4SLinus Torvalds } 2871da177e4SLinus Torvalds 2881da177e4SLinus Torvalds static void __insert_origin(struct origin *o) 2891da177e4SLinus Torvalds { 2901da177e4SLinus Torvalds struct list_head *sl = &_origins[origin_hash(o->bdev)]; 2911da177e4SLinus Torvalds list_add_tail(&o->hash_list, sl); 2921da177e4SLinus Torvalds } 2931da177e4SLinus Torvalds 2941da177e4SLinus Torvalds /* 2951da177e4SLinus Torvalds * Make a note of the snapshot and its origin so we can look it 2961da177e4SLinus Torvalds * up when the origin has a write on it. 2971da177e4SLinus Torvalds */ 2981da177e4SLinus Torvalds static int register_snapshot(struct dm_snapshot *snap) 2991da177e4SLinus Torvalds { 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 3231da177e4SLinus Torvalds list_add_tail(&snap->list, &o->snapshots); 3241da177e4SLinus Torvalds 3251da177e4SLinus Torvalds up_write(&_origins_lock); 3261da177e4SLinus Torvalds return 0; 3271da177e4SLinus Torvalds } 3281da177e4SLinus Torvalds 3291da177e4SLinus Torvalds static void unregister_snapshot(struct dm_snapshot *s) 3301da177e4SLinus Torvalds { 3311da177e4SLinus Torvalds struct origin *o; 3321da177e4SLinus Torvalds 3331da177e4SLinus Torvalds down_write(&_origins_lock); 3341da177e4SLinus Torvalds o = __lookup_origin(s->origin->bdev); 3351da177e4SLinus Torvalds 3361da177e4SLinus Torvalds list_del(&s->list); 3371da177e4SLinus Torvalds if (list_empty(&o->snapshots)) { 3381da177e4SLinus Torvalds list_del(&o->hash_list); 3391da177e4SLinus Torvalds kfree(o); 3401da177e4SLinus Torvalds } 3411da177e4SLinus Torvalds 3421da177e4SLinus Torvalds up_write(&_origins_lock); 3431da177e4SLinus Torvalds } 3441da177e4SLinus Torvalds 3451da177e4SLinus Torvalds /* 3461da177e4SLinus Torvalds * Implementation of the exception hash tables. 347d74f81f8SMilan Broz * The lowest hash_shift bits of the chunk number are ignored, allowing 348d74f81f8SMilan Broz * some consecutive chunks to be grouped together. 3491da177e4SLinus Torvalds */ 350d74f81f8SMilan Broz static int init_exception_table(struct exception_table *et, uint32_t size, 351d74f81f8SMilan Broz unsigned hash_shift) 3521da177e4SLinus Torvalds { 3531da177e4SLinus Torvalds unsigned int i; 3541da177e4SLinus Torvalds 355d74f81f8SMilan Broz et->hash_shift = hash_shift; 3561da177e4SLinus Torvalds et->hash_mask = size - 1; 3571da177e4SLinus Torvalds et->table = dm_vcalloc(size, sizeof(struct list_head)); 3581da177e4SLinus Torvalds if (!et->table) 3591da177e4SLinus Torvalds return -ENOMEM; 3601da177e4SLinus Torvalds 3611da177e4SLinus Torvalds for (i = 0; i < size; i++) 3621da177e4SLinus Torvalds INIT_LIST_HEAD(et->table + i); 3631da177e4SLinus Torvalds 3641da177e4SLinus Torvalds return 0; 3651da177e4SLinus Torvalds } 3661da177e4SLinus Torvalds 367e18b890bSChristoph Lameter static void exit_exception_table(struct exception_table *et, struct kmem_cache *mem) 3681da177e4SLinus Torvalds { 3691da177e4SLinus Torvalds struct list_head *slot; 370028867acSAlasdair G Kergon struct dm_snap_exception *ex, *next; 3711da177e4SLinus Torvalds int i, size; 3721da177e4SLinus Torvalds 3731da177e4SLinus Torvalds size = et->hash_mask + 1; 3741da177e4SLinus Torvalds for (i = 0; i < size; i++) { 3751da177e4SLinus Torvalds slot = et->table + i; 3761da177e4SLinus Torvalds 3771da177e4SLinus Torvalds list_for_each_entry_safe (ex, next, slot, hash_list) 3781da177e4SLinus Torvalds kmem_cache_free(mem, ex); 3791da177e4SLinus Torvalds } 3801da177e4SLinus Torvalds 3811da177e4SLinus Torvalds vfree(et->table); 3821da177e4SLinus Torvalds } 3831da177e4SLinus Torvalds 384028867acSAlasdair G Kergon static uint32_t exception_hash(struct exception_table *et, chunk_t chunk) 3851da177e4SLinus Torvalds { 386d74f81f8SMilan Broz return (chunk >> et->hash_shift) & et->hash_mask; 3871da177e4SLinus Torvalds } 3881da177e4SLinus Torvalds 389028867acSAlasdair G Kergon static void insert_exception(struct exception_table *eh, 390028867acSAlasdair G Kergon struct dm_snap_exception *e) 3911da177e4SLinus Torvalds { 3921da177e4SLinus Torvalds struct list_head *l = &eh->table[exception_hash(eh, e->old_chunk)]; 3931da177e4SLinus Torvalds list_add(&e->hash_list, l); 3941da177e4SLinus Torvalds } 3951da177e4SLinus Torvalds 396028867acSAlasdair G Kergon static void remove_exception(struct dm_snap_exception *e) 3971da177e4SLinus Torvalds { 3981da177e4SLinus Torvalds list_del(&e->hash_list); 3991da177e4SLinus Torvalds } 4001da177e4SLinus Torvalds 4011da177e4SLinus Torvalds /* 4021da177e4SLinus Torvalds * Return the exception data for a sector, or NULL if not 4031da177e4SLinus Torvalds * remapped. 4041da177e4SLinus Torvalds */ 405028867acSAlasdair G Kergon static struct dm_snap_exception *lookup_exception(struct exception_table *et, 4061da177e4SLinus Torvalds chunk_t chunk) 4071da177e4SLinus Torvalds { 4081da177e4SLinus Torvalds struct list_head *slot; 409028867acSAlasdair G Kergon struct dm_snap_exception *e; 4101da177e4SLinus Torvalds 4111da177e4SLinus Torvalds slot = &et->table[exception_hash(et, chunk)]; 4121da177e4SLinus Torvalds list_for_each_entry (e, slot, hash_list) 413d74f81f8SMilan Broz if (chunk >= e->old_chunk && 414d74f81f8SMilan Broz chunk <= e->old_chunk + dm_consecutive_chunk_count(e)) 4151da177e4SLinus Torvalds return e; 4161da177e4SLinus Torvalds 4171da177e4SLinus Torvalds return NULL; 4181da177e4SLinus Torvalds } 4191da177e4SLinus Torvalds 420028867acSAlasdair G Kergon static struct dm_snap_exception *alloc_exception(void) 4211da177e4SLinus Torvalds { 422028867acSAlasdair G Kergon struct dm_snap_exception *e; 4231da177e4SLinus Torvalds 4241da177e4SLinus Torvalds e = kmem_cache_alloc(exception_cache, GFP_NOIO); 4251da177e4SLinus Torvalds if (!e) 4261da177e4SLinus Torvalds e = kmem_cache_alloc(exception_cache, GFP_ATOMIC); 4271da177e4SLinus Torvalds 4281da177e4SLinus Torvalds return e; 4291da177e4SLinus Torvalds } 4301da177e4SLinus Torvalds 431028867acSAlasdair G Kergon static void free_exception(struct dm_snap_exception *e) 4321da177e4SLinus Torvalds { 4331da177e4SLinus Torvalds kmem_cache_free(exception_cache, e); 4341da177e4SLinus Torvalds } 4351da177e4SLinus Torvalds 43692e86812SMikulas Patocka static struct dm_snap_pending_exception *alloc_pending_exception(struct dm_snapshot *s) 4371da177e4SLinus Torvalds { 43892e86812SMikulas Patocka struct dm_snap_pending_exception *pe = mempool_alloc(s->pending_pool, 43992e86812SMikulas Patocka GFP_NOIO); 44092e86812SMikulas Patocka 441879129d2SMikulas Patocka atomic_inc(&s->pending_exceptions_count); 44292e86812SMikulas Patocka pe->snap = s; 44392e86812SMikulas Patocka 44492e86812SMikulas Patocka return pe; 4451da177e4SLinus Torvalds } 4461da177e4SLinus Torvalds 447028867acSAlasdair G Kergon static void free_pending_exception(struct dm_snap_pending_exception *pe) 4481da177e4SLinus Torvalds { 449879129d2SMikulas Patocka struct dm_snapshot *s = pe->snap; 450879129d2SMikulas Patocka 451879129d2SMikulas Patocka mempool_free(pe, s->pending_pool); 452879129d2SMikulas Patocka smp_mb__before_atomic_dec(); 453879129d2SMikulas Patocka atomic_dec(&s->pending_exceptions_count); 4541da177e4SLinus Torvalds } 4551da177e4SLinus Torvalds 456d74f81f8SMilan Broz static void insert_completed_exception(struct dm_snapshot *s, 457d74f81f8SMilan Broz struct dm_snap_exception *new_e) 458d74f81f8SMilan Broz { 459d74f81f8SMilan Broz struct exception_table *eh = &s->complete; 460d74f81f8SMilan Broz struct list_head *l; 461d74f81f8SMilan Broz struct dm_snap_exception *e = NULL; 462d74f81f8SMilan Broz 463d74f81f8SMilan Broz l = &eh->table[exception_hash(eh, new_e->old_chunk)]; 464d74f81f8SMilan Broz 465d74f81f8SMilan Broz /* Add immediately if this table doesn't support consecutive chunks */ 466d74f81f8SMilan Broz if (!eh->hash_shift) 467d74f81f8SMilan Broz goto out; 468d74f81f8SMilan Broz 469d74f81f8SMilan Broz /* List is ordered by old_chunk */ 470d74f81f8SMilan Broz list_for_each_entry_reverse(e, l, hash_list) { 471d74f81f8SMilan Broz /* Insert after an existing chunk? */ 472d74f81f8SMilan Broz if (new_e->old_chunk == (e->old_chunk + 473d74f81f8SMilan Broz dm_consecutive_chunk_count(e) + 1) && 474d74f81f8SMilan Broz new_e->new_chunk == (dm_chunk_number(e->new_chunk) + 475d74f81f8SMilan Broz dm_consecutive_chunk_count(e) + 1)) { 476d74f81f8SMilan Broz dm_consecutive_chunk_count_inc(e); 477d74f81f8SMilan Broz free_exception(new_e); 478d74f81f8SMilan Broz return; 479d74f81f8SMilan Broz } 480d74f81f8SMilan Broz 481d74f81f8SMilan Broz /* Insert before an existing chunk? */ 482d74f81f8SMilan Broz if (new_e->old_chunk == (e->old_chunk - 1) && 483d74f81f8SMilan Broz new_e->new_chunk == (dm_chunk_number(e->new_chunk) - 1)) { 484d74f81f8SMilan Broz dm_consecutive_chunk_count_inc(e); 485d74f81f8SMilan Broz e->old_chunk--; 486d74f81f8SMilan Broz e->new_chunk--; 487d74f81f8SMilan Broz free_exception(new_e); 488d74f81f8SMilan Broz return; 489d74f81f8SMilan Broz } 490d74f81f8SMilan Broz 491d74f81f8SMilan Broz if (new_e->old_chunk > e->old_chunk) 492d74f81f8SMilan Broz break; 493d74f81f8SMilan Broz } 494d74f81f8SMilan Broz 495d74f81f8SMilan Broz out: 496d74f81f8SMilan Broz list_add(&new_e->hash_list, e ? &e->hash_list : l); 497d74f81f8SMilan Broz } 498d74f81f8SMilan Broz 499a159c1acSJonathan Brassow /* 500a159c1acSJonathan Brassow * Callback used by the exception stores to load exceptions when 501a159c1acSJonathan Brassow * initialising. 502a159c1acSJonathan Brassow */ 503a159c1acSJonathan Brassow static int dm_add_exception(void *context, chunk_t old, chunk_t new) 5041da177e4SLinus Torvalds { 505a159c1acSJonathan Brassow struct dm_snapshot *s = context; 506028867acSAlasdair G Kergon struct dm_snap_exception *e; 5071da177e4SLinus Torvalds 5081da177e4SLinus Torvalds e = alloc_exception(); 5091da177e4SLinus Torvalds if (!e) 5101da177e4SLinus Torvalds return -ENOMEM; 5111da177e4SLinus Torvalds 5121da177e4SLinus Torvalds e->old_chunk = old; 513d74f81f8SMilan Broz 514d74f81f8SMilan Broz /* Consecutive_count is implicitly initialised to zero */ 5151da177e4SLinus Torvalds e->new_chunk = new; 516d74f81f8SMilan Broz 517d74f81f8SMilan Broz insert_completed_exception(s, e); 518d74f81f8SMilan Broz 5191da177e4SLinus Torvalds return 0; 5201da177e4SLinus Torvalds } 5211da177e4SLinus Torvalds 5221da177e4SLinus Torvalds /* 5231da177e4SLinus Torvalds * Hard coded magic. 5241da177e4SLinus Torvalds */ 5251da177e4SLinus Torvalds static int calc_max_buckets(void) 5261da177e4SLinus Torvalds { 5271da177e4SLinus Torvalds /* use a fixed size of 2MB */ 5281da177e4SLinus Torvalds unsigned long mem = 2 * 1024 * 1024; 5291da177e4SLinus Torvalds mem /= sizeof(struct list_head); 5301da177e4SLinus Torvalds 5311da177e4SLinus Torvalds return mem; 5321da177e4SLinus Torvalds } 5331da177e4SLinus Torvalds 5341da177e4SLinus Torvalds /* 5351da177e4SLinus Torvalds * Allocate room for a suitable hash table. 5361da177e4SLinus Torvalds */ 537fee1998eSJonathan Brassow static int init_hash_tables(struct dm_snapshot *s) 5381da177e4SLinus Torvalds { 5391da177e4SLinus Torvalds sector_t hash_size, cow_dev_size, origin_dev_size, max_buckets; 5401da177e4SLinus Torvalds 5411da177e4SLinus Torvalds /* 5421da177e4SLinus Torvalds * Calculate based on the size of the original volume or 5431da177e4SLinus Torvalds * the COW volume... 5441da177e4SLinus Torvalds */ 545fee1998eSJonathan Brassow cow_dev_size = get_dev_size(s->store->cow->bdev); 5461da177e4SLinus Torvalds origin_dev_size = get_dev_size(s->origin->bdev); 5471da177e4SLinus Torvalds max_buckets = calc_max_buckets(); 5481da177e4SLinus Torvalds 549fee1998eSJonathan Brassow hash_size = min(origin_dev_size, cow_dev_size) >> s->store->chunk_shift; 5501da177e4SLinus Torvalds hash_size = min(hash_size, max_buckets); 5511da177e4SLinus Torvalds 5528defd830SRobert P. J. Day hash_size = rounddown_pow_of_two(hash_size); 553d74f81f8SMilan Broz if (init_exception_table(&s->complete, hash_size, 554d74f81f8SMilan Broz DM_CHUNK_CONSECUTIVE_BITS)) 5551da177e4SLinus Torvalds return -ENOMEM; 5561da177e4SLinus Torvalds 5571da177e4SLinus Torvalds /* 5581da177e4SLinus Torvalds * Allocate hash table for in-flight exceptions 5591da177e4SLinus Torvalds * Make this smaller than the real hash table 5601da177e4SLinus Torvalds */ 5611da177e4SLinus Torvalds hash_size >>= 3; 5621da177e4SLinus Torvalds if (hash_size < 64) 5631da177e4SLinus Torvalds hash_size = 64; 5641da177e4SLinus Torvalds 565d74f81f8SMilan Broz if (init_exception_table(&s->pending, hash_size, 0)) { 5661da177e4SLinus Torvalds exit_exception_table(&s->complete, exception_cache); 5671da177e4SLinus Torvalds return -ENOMEM; 5681da177e4SLinus Torvalds } 5691da177e4SLinus Torvalds 5701da177e4SLinus Torvalds return 0; 5711da177e4SLinus Torvalds } 5721da177e4SLinus Torvalds 5731da177e4SLinus Torvalds /* 5741da177e4SLinus Torvalds * Construct a snapshot mapping: <origin_dev> <COW-dev> <p/n> <chunk-size> 5751da177e4SLinus Torvalds */ 5761da177e4SLinus Torvalds static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv) 5771da177e4SLinus Torvalds { 5781da177e4SLinus Torvalds struct dm_snapshot *s; 579cd45daffSMikulas Patocka int i; 5801da177e4SLinus Torvalds int r = -EINVAL; 5811da177e4SLinus Torvalds char *origin_path; 582fee1998eSJonathan Brassow struct dm_exception_store *store; 583fee1998eSJonathan Brassow unsigned args_used; 5841da177e4SLinus Torvalds 5854c7e3bf4SMark McLoughlin if (argc != 4) { 58672d94861SAlasdair G Kergon ti->error = "requires exactly 4 arguments"; 5871da177e4SLinus Torvalds r = -EINVAL; 588fee1998eSJonathan Brassow goto bad_args; 5891da177e4SLinus Torvalds } 5901da177e4SLinus Torvalds 5911da177e4SLinus Torvalds origin_path = argv[0]; 592fee1998eSJonathan Brassow argv++; 593fee1998eSJonathan Brassow argc--; 5941da177e4SLinus Torvalds 595fee1998eSJonathan Brassow r = dm_exception_store_create(ti, argc, argv, &args_used, &store); 596fee1998eSJonathan Brassow if (r) { 597fee1998eSJonathan Brassow ti->error = "Couldn't create exception store"; 5981da177e4SLinus Torvalds r = -EINVAL; 599fee1998eSJonathan Brassow goto bad_args; 6001da177e4SLinus Torvalds } 6011da177e4SLinus Torvalds 602fee1998eSJonathan Brassow argv += args_used; 603fee1998eSJonathan Brassow argc -= args_used; 604fee1998eSJonathan Brassow 6051da177e4SLinus Torvalds s = kmalloc(sizeof(*s), GFP_KERNEL); 606fee1998eSJonathan Brassow if (!s) { 6071da177e4SLinus Torvalds ti->error = "Cannot allocate snapshot context private " 6081da177e4SLinus Torvalds "structure"; 6091da177e4SLinus Torvalds r = -ENOMEM; 610fee1998eSJonathan Brassow goto bad_snap; 6111da177e4SLinus Torvalds } 6121da177e4SLinus Torvalds 6131da177e4SLinus Torvalds r = dm_get_device(ti, origin_path, 0, ti->len, FMODE_READ, &s->origin); 6141da177e4SLinus Torvalds if (r) { 6151da177e4SLinus Torvalds ti->error = "Cannot get origin device"; 616fee1998eSJonathan Brassow goto bad_origin; 6171da177e4SLinus Torvalds } 6181da177e4SLinus Torvalds 619fee1998eSJonathan Brassow s->store = store; 6201da177e4SLinus Torvalds s->valid = 1; 621aa14edebSAlasdair G Kergon s->active = 0; 622879129d2SMikulas Patocka atomic_set(&s->pending_exceptions_count, 0); 6231da177e4SLinus Torvalds init_rwsem(&s->lock); 624ca3a931fSAlasdair G Kergon spin_lock_init(&s->pe_lock); 6251da177e4SLinus Torvalds 6261da177e4SLinus Torvalds /* Allocate hash table for COW data */ 627fee1998eSJonathan Brassow if (init_hash_tables(s)) { 6281da177e4SLinus Torvalds ti->error = "Unable to allocate hash table space"; 6291da177e4SLinus Torvalds r = -ENOMEM; 630fee1998eSJonathan Brassow goto bad_hash_tables; 6311da177e4SLinus Torvalds } 6321da177e4SLinus Torvalds 633eb69aca5SHeinz Mauelshagen r = dm_kcopyd_client_create(SNAPSHOT_PAGES, &s->kcopyd_client); 6341da177e4SLinus Torvalds if (r) { 6351da177e4SLinus Torvalds ti->error = "Could not create kcopyd client"; 636fee1998eSJonathan Brassow goto bad_kcopyd; 6371da177e4SLinus Torvalds } 6381da177e4SLinus Torvalds 63992e86812SMikulas Patocka s->pending_pool = mempool_create_slab_pool(MIN_IOS, pending_cache); 64092e86812SMikulas Patocka if (!s->pending_pool) { 64192e86812SMikulas Patocka ti->error = "Could not allocate mempool for pending exceptions"; 642fee1998eSJonathan Brassow goto bad_pending_pool; 64392e86812SMikulas Patocka } 64492e86812SMikulas Patocka 645cd45daffSMikulas Patocka s->tracked_chunk_pool = mempool_create_slab_pool(MIN_IOS, 646cd45daffSMikulas Patocka tracked_chunk_cache); 647cd45daffSMikulas Patocka if (!s->tracked_chunk_pool) { 648cd45daffSMikulas Patocka ti->error = "Could not allocate tracked_chunk mempool for " 649cd45daffSMikulas Patocka "tracking reads"; 65092e86812SMikulas Patocka goto bad_tracked_chunk_pool; 651cd45daffSMikulas Patocka } 652cd45daffSMikulas Patocka 653cd45daffSMikulas Patocka for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) 654cd45daffSMikulas Patocka INIT_HLIST_HEAD(&s->tracked_chunk_hash[i]); 655cd45daffSMikulas Patocka 656cd45daffSMikulas Patocka spin_lock_init(&s->tracked_chunk_lock); 657cd45daffSMikulas Patocka 658aa14edebSAlasdair G Kergon /* Metadata must only be loaded into one table at once */ 659493df71cSJonathan Brassow r = s->store->type->read_metadata(s->store, dm_add_exception, 660493df71cSJonathan Brassow (void *)s); 6610764147bSMilan Broz if (r < 0) { 662f9cea4f7SMark McLoughlin ti->error = "Failed to read snapshot metadata"; 663cd45daffSMikulas Patocka goto bad_load_and_register; 6640764147bSMilan Broz } else if (r > 0) { 6650764147bSMilan Broz s->valid = 0; 6660764147bSMilan Broz DMWARN("Snapshot is marked invalid."); 667f9cea4f7SMark McLoughlin } 668aa14edebSAlasdair G Kergon 669ca3a931fSAlasdair G Kergon bio_list_init(&s->queued_bios); 670c4028958SDavid Howells INIT_WORK(&s->queued_bios_work, flush_queued_bios); 671ca3a931fSAlasdair G Kergon 6721da177e4SLinus Torvalds /* Add snapshot to the list of snapshots for this origin */ 673aa14edebSAlasdair G Kergon /* Exceptions aren't triggered till snapshot_resume() is called */ 6741da177e4SLinus Torvalds if (register_snapshot(s)) { 6751da177e4SLinus Torvalds r = -EINVAL; 6761da177e4SLinus Torvalds ti->error = "Cannot register snapshot origin"; 677cd45daffSMikulas Patocka goto bad_load_and_register; 6781da177e4SLinus Torvalds } 6791da177e4SLinus Torvalds 6801da177e4SLinus Torvalds ti->private = s; 681d0216849SJonathan Brassow ti->split_io = s->store->chunk_size; 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 103471fab00aSJonathan Brassow chunk = sector_to_chunk(s->store, bio->bi_sector); 10351da177e4SLinus Torvalds 10361da177e4SLinus Torvalds /* Full snapshots are not usable */ 103776df1c65SAlasdair G Kergon /* To get here the table must be live so s->active is always set. */ 10381da177e4SLinus Torvalds if (!s->valid) 1039f6a80ea8SAlasdair G Kergon return -EIO; 10401da177e4SLinus Torvalds 10411da177e4SLinus Torvalds /* FIXME: should only take write lock if we need 10421da177e4SLinus Torvalds * to copy an exception */ 10431da177e4SLinus Torvalds down_write(&s->lock); 10441da177e4SLinus Torvalds 104576df1c65SAlasdair G Kergon if (!s->valid) { 104676df1c65SAlasdair G Kergon r = -EIO; 104776df1c65SAlasdair G Kergon goto out_unlock; 104876df1c65SAlasdair G Kergon } 104976df1c65SAlasdair G Kergon 10501da177e4SLinus Torvalds /* If the block is already remapped - use that, else remap it */ 10511da177e4SLinus Torvalds e = lookup_exception(&s->complete, chunk); 10521da177e4SLinus Torvalds if (e) { 1053d74f81f8SMilan Broz remap_exception(s, e, bio, chunk); 105476df1c65SAlasdair G Kergon goto out_unlock; 105576df1c65SAlasdair G Kergon } 10561da177e4SLinus Torvalds 1057ba40a2aaSAlasdair G Kergon /* 1058ba40a2aaSAlasdair G Kergon * Write to snapshot - higher level takes care of RW/RO 1059ba40a2aaSAlasdair G Kergon * flags so we should only get this if we are 1060ba40a2aaSAlasdair G Kergon * writeable. 1061ba40a2aaSAlasdair G Kergon */ 1062ba40a2aaSAlasdair G Kergon if (bio_rw(bio) == WRITE) { 10632913808eSMikulas Patocka pe = __lookup_pending_exception(s, chunk); 10642913808eSMikulas Patocka if (!pe) { 1065c6621392SMikulas Patocka up_write(&s->lock); 1066c6621392SMikulas Patocka pe = alloc_pending_exception(s); 1067c6621392SMikulas Patocka down_write(&s->lock); 1068c6621392SMikulas Patocka 1069c6621392SMikulas Patocka if (!s->valid) { 1070c6621392SMikulas Patocka free_pending_exception(pe); 1071c6621392SMikulas Patocka r = -EIO; 1072c6621392SMikulas Patocka goto out_unlock; 1073c6621392SMikulas Patocka } 1074c6621392SMikulas Patocka 107535bf659bSMikulas Patocka e = lookup_exception(&s->complete, chunk); 107635bf659bSMikulas Patocka if (e) { 107735bf659bSMikulas Patocka free_pending_exception(pe); 107835bf659bSMikulas Patocka remap_exception(s, e, bio, chunk); 107935bf659bSMikulas Patocka goto out_unlock; 108035bf659bSMikulas Patocka } 108135bf659bSMikulas Patocka 1082c6621392SMikulas Patocka pe = __find_pending_exception(s, pe, chunk); 10831da177e4SLinus Torvalds if (!pe) { 1084695368acSAlasdair G Kergon __invalidate_snapshot(s, -ENOMEM); 10851da177e4SLinus Torvalds r = -EIO; 108676df1c65SAlasdair G Kergon goto out_unlock; 108776df1c65SAlasdair G Kergon } 10882913808eSMikulas Patocka } 108976df1c65SAlasdair G Kergon 1090d74f81f8SMilan Broz remap_exception(s, &pe->e, bio, chunk); 10911da177e4SLinus Torvalds bio_list_add(&pe->snapshot_bios, bio); 10921da177e4SLinus Torvalds 1093d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 1094ba40a2aaSAlasdair G Kergon 10951da177e4SLinus Torvalds if (!pe->started) { 10961da177e4SLinus Torvalds /* this is protected by snap->lock */ 10971da177e4SLinus Torvalds pe->started = 1; 109876df1c65SAlasdair G Kergon up_write(&s->lock); 109976df1c65SAlasdair G Kergon start_copy(pe); 1100ba40a2aaSAlasdair G Kergon goto out; 1101ba40a2aaSAlasdair G Kergon } 1102cd45daffSMikulas Patocka } else { 11031da177e4SLinus Torvalds bio->bi_bdev = s->origin->bdev; 1104cd45daffSMikulas Patocka map_context->ptr = track_chunk(s, chunk); 1105cd45daffSMikulas Patocka } 11061da177e4SLinus Torvalds 1107ba40a2aaSAlasdair G Kergon out_unlock: 1108ba40a2aaSAlasdair G Kergon up_write(&s->lock); 1109ba40a2aaSAlasdair G Kergon out: 11101da177e4SLinus Torvalds return r; 11111da177e4SLinus Torvalds } 11121da177e4SLinus Torvalds 1113cd45daffSMikulas Patocka static int snapshot_end_io(struct dm_target *ti, struct bio *bio, 1114cd45daffSMikulas Patocka int error, union map_info *map_context) 1115cd45daffSMikulas Patocka { 1116cd45daffSMikulas Patocka struct dm_snapshot *s = ti->private; 1117cd45daffSMikulas Patocka struct dm_snap_tracked_chunk *c = map_context->ptr; 1118cd45daffSMikulas Patocka 1119cd45daffSMikulas Patocka if (c) 1120cd45daffSMikulas Patocka stop_tracking_chunk(s, c); 1121cd45daffSMikulas Patocka 1122cd45daffSMikulas Patocka return 0; 1123cd45daffSMikulas Patocka } 1124cd45daffSMikulas Patocka 11251da177e4SLinus Torvalds static void snapshot_resume(struct dm_target *ti) 11261da177e4SLinus Torvalds { 1127028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 11281da177e4SLinus Torvalds 1129aa14edebSAlasdair G Kergon down_write(&s->lock); 1130aa14edebSAlasdair G Kergon s->active = 1; 1131aa14edebSAlasdair G Kergon up_write(&s->lock); 11321da177e4SLinus Torvalds } 11331da177e4SLinus Torvalds 11341da177e4SLinus Torvalds static int snapshot_status(struct dm_target *ti, status_type_t type, 11351da177e4SLinus Torvalds char *result, unsigned int maxlen) 11361da177e4SLinus Torvalds { 11372e4a31dfSJonathan Brassow unsigned sz = 0; 1138028867acSAlasdair G Kergon struct dm_snapshot *snap = ti->private; 11391da177e4SLinus Torvalds 11401da177e4SLinus Torvalds switch (type) { 11411da177e4SLinus Torvalds case STATUSTYPE_INFO: 11421da177e4SLinus Torvalds if (!snap->valid) 11432e4a31dfSJonathan Brassow DMEMIT("Invalid"); 11441da177e4SLinus Torvalds else { 1145493df71cSJonathan Brassow if (snap->store->type->fraction_full) { 11461da177e4SLinus Torvalds sector_t numerator, denominator; 1147493df71cSJonathan Brassow snap->store->type->fraction_full(snap->store, 11481da177e4SLinus Torvalds &numerator, 11491da177e4SLinus Torvalds &denominator); 11502e4a31dfSJonathan Brassow DMEMIT("%llu/%llu", 11514ee218cdSAndrew Morton (unsigned long long)numerator, 11524ee218cdSAndrew Morton (unsigned long long)denominator); 11531da177e4SLinus Torvalds } 11541da177e4SLinus Torvalds else 11552e4a31dfSJonathan Brassow DMEMIT("Unknown"); 11561da177e4SLinus Torvalds } 11571da177e4SLinus Torvalds break; 11581da177e4SLinus Torvalds 11591da177e4SLinus Torvalds case STATUSTYPE_TABLE: 11601da177e4SLinus Torvalds /* 11611da177e4SLinus Torvalds * kdevname returns a static pointer so we need 11621da177e4SLinus Torvalds * to make private copies if the output is to 11631da177e4SLinus Torvalds * make sense. 11641da177e4SLinus Torvalds */ 11652e4a31dfSJonathan Brassow DMEMIT("%s", snap->origin->name); 11661e302a92SJonathan Brassow snap->store->type->status(snap->store, type, result + sz, 11671e302a92SJonathan Brassow maxlen - sz); 11681da177e4SLinus Torvalds break; 11691da177e4SLinus Torvalds } 11701da177e4SLinus Torvalds 11711da177e4SLinus Torvalds return 0; 11721da177e4SLinus Torvalds } 11731da177e4SLinus Torvalds 11741da177e4SLinus Torvalds /*----------------------------------------------------------------- 11751da177e4SLinus Torvalds * Origin methods 11761da177e4SLinus Torvalds *---------------------------------------------------------------*/ 11771da177e4SLinus Torvalds static int __origin_write(struct list_head *snapshots, struct bio *bio) 11781da177e4SLinus Torvalds { 1179d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED, first = 0; 11801da177e4SLinus Torvalds struct dm_snapshot *snap; 1181028867acSAlasdair G Kergon struct dm_snap_exception *e; 1182028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe, *next_pe, *primary_pe = NULL; 11831da177e4SLinus Torvalds chunk_t chunk; 1184eccf0817SAlasdair G Kergon LIST_HEAD(pe_queue); 11851da177e4SLinus Torvalds 11861da177e4SLinus Torvalds /* Do all the snapshots on this origin */ 11871da177e4SLinus Torvalds list_for_each_entry (snap, snapshots, list) { 11881da177e4SLinus Torvalds 118976df1c65SAlasdair G Kergon down_write(&snap->lock); 119076df1c65SAlasdair G Kergon 1191aa14edebSAlasdair G Kergon /* Only deal with valid and active snapshots */ 1192aa14edebSAlasdair G Kergon if (!snap->valid || !snap->active) 119376df1c65SAlasdair G Kergon goto next_snapshot; 11941da177e4SLinus Torvalds 1195d5e404c1SAlasdair G Kergon /* Nothing to do if writing beyond end of snapshot */ 11960cea9c78SJonathan Brassow if (bio->bi_sector >= dm_table_get_size(snap->store->ti->table)) 119776df1c65SAlasdair G Kergon goto next_snapshot; 11981da177e4SLinus Torvalds 11991da177e4SLinus Torvalds /* 12001da177e4SLinus Torvalds * Remember, different snapshots can have 12011da177e4SLinus Torvalds * different chunk sizes. 12021da177e4SLinus Torvalds */ 120371fab00aSJonathan Brassow chunk = sector_to_chunk(snap->store, bio->bi_sector); 12041da177e4SLinus Torvalds 12051da177e4SLinus Torvalds /* 12061da177e4SLinus Torvalds * Check exception table to see if block 12071da177e4SLinus Torvalds * is already remapped in this snapshot 12081da177e4SLinus Torvalds * and trigger an exception if not. 1209b4b610f6SAlasdair G Kergon * 12104b832e8dSAlasdair G Kergon * ref_count is initialised to 1 so pending_complete() 1211b4b610f6SAlasdair G Kergon * won't destroy the primary_pe while we're inside this loop. 12121da177e4SLinus Torvalds */ 12131da177e4SLinus Torvalds e = lookup_exception(&snap->complete, chunk); 121476df1c65SAlasdair G Kergon if (e) 121576df1c65SAlasdair G Kergon goto next_snapshot; 121676df1c65SAlasdair G Kergon 12172913808eSMikulas Patocka pe = __lookup_pending_exception(snap, chunk); 12182913808eSMikulas Patocka if (!pe) { 1219c6621392SMikulas Patocka up_write(&snap->lock); 1220c6621392SMikulas Patocka pe = alloc_pending_exception(snap); 1221c6621392SMikulas Patocka down_write(&snap->lock); 1222c6621392SMikulas Patocka 1223c6621392SMikulas Patocka if (!snap->valid) { 1224c6621392SMikulas Patocka free_pending_exception(pe); 1225c6621392SMikulas Patocka goto next_snapshot; 1226c6621392SMikulas Patocka } 1227c6621392SMikulas Patocka 122835bf659bSMikulas Patocka e = lookup_exception(&snap->complete, chunk); 122935bf659bSMikulas Patocka if (e) { 123035bf659bSMikulas Patocka free_pending_exception(pe); 123135bf659bSMikulas Patocka goto next_snapshot; 123235bf659bSMikulas Patocka } 123335bf659bSMikulas Patocka 1234c6621392SMikulas Patocka pe = __find_pending_exception(snap, pe, chunk); 12351da177e4SLinus Torvalds if (!pe) { 1236695368acSAlasdair G Kergon __invalidate_snapshot(snap, -ENOMEM); 123776df1c65SAlasdair G Kergon goto next_snapshot; 123876df1c65SAlasdair G Kergon } 12392913808eSMikulas Patocka } 12401da177e4SLinus Torvalds 1241b4b610f6SAlasdair G Kergon if (!primary_pe) { 1242b4b610f6SAlasdair G Kergon /* 1243b4b610f6SAlasdair G Kergon * Either every pe here has same 1244b4b610f6SAlasdair G Kergon * primary_pe or none has one yet. 1245b4b610f6SAlasdair G Kergon */ 1246b4b610f6SAlasdair G Kergon if (pe->primary_pe) 1247b4b610f6SAlasdair G Kergon primary_pe = pe->primary_pe; 1248b4b610f6SAlasdair G Kergon else { 1249b4b610f6SAlasdair G Kergon primary_pe = pe; 1250b4b610f6SAlasdair G Kergon first = 1; 1251eccf0817SAlasdair G Kergon } 1252b4b610f6SAlasdair G Kergon 125376df1c65SAlasdair G Kergon bio_list_add(&primary_pe->origin_bios, bio); 125476df1c65SAlasdair G Kergon 1255d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 1256b4b610f6SAlasdair G Kergon } 125776df1c65SAlasdair G Kergon 1258b4b610f6SAlasdair G Kergon if (!pe->primary_pe) { 1259b4b610f6SAlasdair G Kergon pe->primary_pe = primary_pe; 12604b832e8dSAlasdair G Kergon get_pending_exception(primary_pe); 1261b4b610f6SAlasdair G Kergon } 126276df1c65SAlasdair G Kergon 1263eccf0817SAlasdair G Kergon if (!pe->started) { 1264eccf0817SAlasdair G Kergon pe->started = 1; 1265eccf0817SAlasdair G Kergon list_add_tail(&pe->list, &pe_queue); 1266eccf0817SAlasdair G Kergon } 12671da177e4SLinus Torvalds 126876df1c65SAlasdair G Kergon next_snapshot: 12691da177e4SLinus Torvalds up_write(&snap->lock); 12701da177e4SLinus Torvalds } 12711da177e4SLinus Torvalds 1272b4b610f6SAlasdair G Kergon if (!primary_pe) 12734b832e8dSAlasdair G Kergon return r; 1274b4b610f6SAlasdair G Kergon 1275b4b610f6SAlasdair G Kergon /* 1276b4b610f6SAlasdair G Kergon * If this is the first time we're processing this chunk and 12774b832e8dSAlasdair G Kergon * ref_count is now 1 it means all the pending exceptions 1278b4b610f6SAlasdair G Kergon * got completed while we were in the loop above, so it falls to 1279b4b610f6SAlasdair G Kergon * us here to remove the primary_pe and submit any origin_bios. 1280b4b610f6SAlasdair G Kergon */ 1281b4b610f6SAlasdair G Kergon 12824b832e8dSAlasdair G Kergon if (first && atomic_dec_and_test(&primary_pe->ref_count)) { 1283b4b610f6SAlasdair G Kergon flush_bios(bio_list_get(&primary_pe->origin_bios)); 1284b4b610f6SAlasdair G Kergon free_pending_exception(primary_pe); 1285b4b610f6SAlasdair G Kergon /* If we got here, pe_queue is necessarily empty. */ 12864b832e8dSAlasdair G Kergon return r; 1287b4b610f6SAlasdair G Kergon } 1288b4b610f6SAlasdair G Kergon 12891da177e4SLinus Torvalds /* 12901da177e4SLinus Torvalds * Now that we have a complete pe list we can start the copying. 12911da177e4SLinus Torvalds */ 1292eccf0817SAlasdair G Kergon list_for_each_entry_safe(pe, next_pe, &pe_queue, list) 12931da177e4SLinus Torvalds start_copy(pe); 12941da177e4SLinus Torvalds 12951da177e4SLinus Torvalds return r; 12961da177e4SLinus Torvalds } 12971da177e4SLinus Torvalds 12981da177e4SLinus Torvalds /* 12991da177e4SLinus Torvalds * Called on a write from the origin driver. 13001da177e4SLinus Torvalds */ 13011da177e4SLinus Torvalds static int do_origin(struct dm_dev *origin, struct bio *bio) 13021da177e4SLinus Torvalds { 13031da177e4SLinus Torvalds struct origin *o; 1304d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED; 13051da177e4SLinus Torvalds 13061da177e4SLinus Torvalds down_read(&_origins_lock); 13071da177e4SLinus Torvalds o = __lookup_origin(origin->bdev); 13081da177e4SLinus Torvalds if (o) 13091da177e4SLinus Torvalds r = __origin_write(&o->snapshots, bio); 13101da177e4SLinus Torvalds up_read(&_origins_lock); 13111da177e4SLinus Torvalds 13121da177e4SLinus Torvalds return r; 13131da177e4SLinus Torvalds } 13141da177e4SLinus Torvalds 13151da177e4SLinus Torvalds /* 13161da177e4SLinus Torvalds * Origin: maps a linear range of a device, with hooks for snapshotting. 13171da177e4SLinus Torvalds */ 13181da177e4SLinus Torvalds 13191da177e4SLinus Torvalds /* 13201da177e4SLinus Torvalds * Construct an origin mapping: <dev_path> 13211da177e4SLinus Torvalds * The context for an origin is merely a 'struct dm_dev *' 13221da177e4SLinus Torvalds * pointing to the real device. 13231da177e4SLinus Torvalds */ 13241da177e4SLinus Torvalds static int origin_ctr(struct dm_target *ti, unsigned int argc, char **argv) 13251da177e4SLinus Torvalds { 13261da177e4SLinus Torvalds int r; 13271da177e4SLinus Torvalds struct dm_dev *dev; 13281da177e4SLinus Torvalds 13291da177e4SLinus Torvalds if (argc != 1) { 133072d94861SAlasdair G Kergon ti->error = "origin: incorrect number of arguments"; 13311da177e4SLinus Torvalds return -EINVAL; 13321da177e4SLinus Torvalds } 13331da177e4SLinus Torvalds 13341da177e4SLinus Torvalds r = dm_get_device(ti, argv[0], 0, ti->len, 13351da177e4SLinus Torvalds dm_table_get_mode(ti->table), &dev); 13361da177e4SLinus Torvalds if (r) { 13371da177e4SLinus Torvalds ti->error = "Cannot get target device"; 13381da177e4SLinus Torvalds return r; 13391da177e4SLinus Torvalds } 13401da177e4SLinus Torvalds 13411da177e4SLinus Torvalds ti->private = dev; 13421da177e4SLinus Torvalds return 0; 13431da177e4SLinus Torvalds } 13441da177e4SLinus Torvalds 13451da177e4SLinus Torvalds static void origin_dtr(struct dm_target *ti) 13461da177e4SLinus Torvalds { 1347028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 13481da177e4SLinus Torvalds dm_put_device(ti, dev); 13491da177e4SLinus Torvalds } 13501da177e4SLinus Torvalds 13511da177e4SLinus Torvalds static int origin_map(struct dm_target *ti, struct bio *bio, 13521da177e4SLinus Torvalds union map_info *map_context) 13531da177e4SLinus Torvalds { 1354028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 13551da177e4SLinus Torvalds bio->bi_bdev = dev->bdev; 13561da177e4SLinus Torvalds 13571da177e4SLinus Torvalds /* Only tell snapshots if this is a write */ 1358d2a7ad29SKiyoshi Ueda return (bio_rw(bio) == WRITE) ? do_origin(dev, bio) : DM_MAPIO_REMAPPED; 13591da177e4SLinus Torvalds } 13601da177e4SLinus Torvalds 13611da177e4SLinus Torvalds #define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r)) 13621da177e4SLinus Torvalds 13631da177e4SLinus Torvalds /* 13641da177e4SLinus Torvalds * Set the target "split_io" field to the minimum of all the snapshots' 13651da177e4SLinus Torvalds * chunk sizes. 13661da177e4SLinus Torvalds */ 13671da177e4SLinus Torvalds static void origin_resume(struct dm_target *ti) 13681da177e4SLinus Torvalds { 1369028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 13701da177e4SLinus Torvalds struct dm_snapshot *snap; 13711da177e4SLinus Torvalds struct origin *o; 13721da177e4SLinus Torvalds chunk_t chunk_size = 0; 13731da177e4SLinus Torvalds 13741da177e4SLinus Torvalds down_read(&_origins_lock); 13751da177e4SLinus Torvalds o = __lookup_origin(dev->bdev); 13761da177e4SLinus Torvalds if (o) 13771da177e4SLinus Torvalds list_for_each_entry (snap, &o->snapshots, list) 1378d0216849SJonathan Brassow chunk_size = min_not_zero(chunk_size, 1379d0216849SJonathan Brassow snap->store->chunk_size); 13801da177e4SLinus Torvalds up_read(&_origins_lock); 13811da177e4SLinus Torvalds 13821da177e4SLinus Torvalds ti->split_io = chunk_size; 13831da177e4SLinus Torvalds } 13841da177e4SLinus Torvalds 13851da177e4SLinus Torvalds static int origin_status(struct dm_target *ti, status_type_t type, char *result, 13861da177e4SLinus Torvalds unsigned int maxlen) 13871da177e4SLinus Torvalds { 1388028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 13891da177e4SLinus Torvalds 13901da177e4SLinus Torvalds switch (type) { 13911da177e4SLinus Torvalds case STATUSTYPE_INFO: 13921da177e4SLinus Torvalds result[0] = '\0'; 13931da177e4SLinus Torvalds break; 13941da177e4SLinus Torvalds 13951da177e4SLinus Torvalds case STATUSTYPE_TABLE: 13961da177e4SLinus Torvalds snprintf(result, maxlen, "%s", dev->name); 13971da177e4SLinus Torvalds break; 13981da177e4SLinus Torvalds } 13991da177e4SLinus Torvalds 14001da177e4SLinus Torvalds return 0; 14011da177e4SLinus Torvalds } 14021da177e4SLinus Torvalds 14031da177e4SLinus Torvalds static struct target_type origin_target = { 14041da177e4SLinus Torvalds .name = "snapshot-origin", 1405d74f81f8SMilan Broz .version = {1, 6, 0}, 14061da177e4SLinus Torvalds .module = THIS_MODULE, 14071da177e4SLinus Torvalds .ctr = origin_ctr, 14081da177e4SLinus Torvalds .dtr = origin_dtr, 14091da177e4SLinus Torvalds .map = origin_map, 14101da177e4SLinus Torvalds .resume = origin_resume, 14111da177e4SLinus Torvalds .status = origin_status, 14121da177e4SLinus Torvalds }; 14131da177e4SLinus Torvalds 14141da177e4SLinus Torvalds static struct target_type snapshot_target = { 14151da177e4SLinus Torvalds .name = "snapshot", 1416d74f81f8SMilan Broz .version = {1, 6, 0}, 14171da177e4SLinus Torvalds .module = THIS_MODULE, 14181da177e4SLinus Torvalds .ctr = snapshot_ctr, 14191da177e4SLinus Torvalds .dtr = snapshot_dtr, 14201da177e4SLinus Torvalds .map = snapshot_map, 1421cd45daffSMikulas Patocka .end_io = snapshot_end_io, 14221da177e4SLinus Torvalds .resume = snapshot_resume, 14231da177e4SLinus Torvalds .status = snapshot_status, 14241da177e4SLinus Torvalds }; 14251da177e4SLinus Torvalds 14261da177e4SLinus Torvalds static int __init dm_snapshot_init(void) 14271da177e4SLinus Torvalds { 14281da177e4SLinus Torvalds int r; 14291da177e4SLinus Torvalds 14304db6bfe0SAlasdair G Kergon r = dm_exception_store_init(); 14314db6bfe0SAlasdair G Kergon if (r) { 14324db6bfe0SAlasdair G Kergon DMERR("Failed to initialize exception stores"); 14334db6bfe0SAlasdair G Kergon return r; 14344db6bfe0SAlasdair G Kergon } 14354db6bfe0SAlasdair G Kergon 14361da177e4SLinus Torvalds r = dm_register_target(&snapshot_target); 14371da177e4SLinus Torvalds if (r) { 14381da177e4SLinus Torvalds DMERR("snapshot target register failed %d", r); 14391da177e4SLinus Torvalds return r; 14401da177e4SLinus Torvalds } 14411da177e4SLinus Torvalds 14421da177e4SLinus Torvalds r = dm_register_target(&origin_target); 14431da177e4SLinus Torvalds if (r < 0) { 144472d94861SAlasdair G Kergon DMERR("Origin target register failed %d", r); 14451da177e4SLinus Torvalds goto bad1; 14461da177e4SLinus Torvalds } 14471da177e4SLinus Torvalds 14481da177e4SLinus Torvalds r = init_origin_hash(); 14491da177e4SLinus Torvalds if (r) { 14501da177e4SLinus Torvalds DMERR("init_origin_hash failed."); 14511da177e4SLinus Torvalds goto bad2; 14521da177e4SLinus Torvalds } 14531da177e4SLinus Torvalds 1454028867acSAlasdair G Kergon exception_cache = KMEM_CACHE(dm_snap_exception, 0); 14551da177e4SLinus Torvalds if (!exception_cache) { 14561da177e4SLinus Torvalds DMERR("Couldn't create exception cache."); 14571da177e4SLinus Torvalds r = -ENOMEM; 14581da177e4SLinus Torvalds goto bad3; 14591da177e4SLinus Torvalds } 14601da177e4SLinus Torvalds 1461028867acSAlasdair G Kergon pending_cache = KMEM_CACHE(dm_snap_pending_exception, 0); 14621da177e4SLinus Torvalds if (!pending_cache) { 14631da177e4SLinus Torvalds DMERR("Couldn't create pending cache."); 14641da177e4SLinus Torvalds r = -ENOMEM; 14651da177e4SLinus Torvalds goto bad4; 14661da177e4SLinus Torvalds } 14671da177e4SLinus Torvalds 1468cd45daffSMikulas Patocka tracked_chunk_cache = KMEM_CACHE(dm_snap_tracked_chunk, 0); 1469cd45daffSMikulas Patocka if (!tracked_chunk_cache) { 1470cd45daffSMikulas Patocka DMERR("Couldn't create cache to track chunks in use."); 1471cd45daffSMikulas Patocka r = -ENOMEM; 1472cd45daffSMikulas Patocka goto bad5; 1473cd45daffSMikulas Patocka } 1474cd45daffSMikulas Patocka 1475ca3a931fSAlasdair G Kergon ksnapd = create_singlethread_workqueue("ksnapd"); 1476ca3a931fSAlasdair G Kergon if (!ksnapd) { 1477ca3a931fSAlasdair G Kergon DMERR("Failed to create ksnapd workqueue."); 1478ca3a931fSAlasdair G Kergon r = -ENOMEM; 147992e86812SMikulas Patocka goto bad_pending_pool; 1480ca3a931fSAlasdair G Kergon } 1481ca3a931fSAlasdair G Kergon 14821da177e4SLinus Torvalds return 0; 14831da177e4SLinus Torvalds 1484cd45daffSMikulas Patocka bad_pending_pool: 1485cd45daffSMikulas Patocka kmem_cache_destroy(tracked_chunk_cache); 14861da177e4SLinus Torvalds bad5: 14871da177e4SLinus Torvalds kmem_cache_destroy(pending_cache); 14881da177e4SLinus Torvalds bad4: 14891da177e4SLinus Torvalds kmem_cache_destroy(exception_cache); 14901da177e4SLinus Torvalds bad3: 14911da177e4SLinus Torvalds exit_origin_hash(); 14921da177e4SLinus Torvalds bad2: 14931da177e4SLinus Torvalds dm_unregister_target(&origin_target); 14941da177e4SLinus Torvalds bad1: 14951da177e4SLinus Torvalds dm_unregister_target(&snapshot_target); 14961da177e4SLinus Torvalds return r; 14971da177e4SLinus Torvalds } 14981da177e4SLinus Torvalds 14991da177e4SLinus Torvalds static void __exit dm_snapshot_exit(void) 15001da177e4SLinus Torvalds { 1501ca3a931fSAlasdair G Kergon destroy_workqueue(ksnapd); 1502ca3a931fSAlasdair G Kergon 150310d3bd09SMikulas Patocka dm_unregister_target(&snapshot_target); 150410d3bd09SMikulas Patocka dm_unregister_target(&origin_target); 15051da177e4SLinus Torvalds 15061da177e4SLinus Torvalds exit_origin_hash(); 15071da177e4SLinus Torvalds kmem_cache_destroy(pending_cache); 15081da177e4SLinus Torvalds kmem_cache_destroy(exception_cache); 1509cd45daffSMikulas Patocka kmem_cache_destroy(tracked_chunk_cache); 15104db6bfe0SAlasdair G Kergon 15114db6bfe0SAlasdair G Kergon dm_exception_store_exit(); 15121da177e4SLinus Torvalds } 15131da177e4SLinus Torvalds 15141da177e4SLinus Torvalds /* Module hooks */ 15151da177e4SLinus Torvalds module_init(dm_snapshot_init); 15161da177e4SLinus Torvalds module_exit(dm_snapshot_exit); 15171da177e4SLinus Torvalds 15181da177e4SLinus Torvalds MODULE_DESCRIPTION(DM_NAME " snapshot target"); 15191da177e4SLinus Torvalds MODULE_AUTHOR("Joe Thornber"); 15201da177e4SLinus Torvalds MODULE_LICENSE("GPL"); 1521