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 /* Used for display of table */ 74ccc45ea8SJonathan Brassow char type; 75ccc45ea8SJonathan Brassow 76ccc45ea8SJonathan Brassow mempool_t *pending_pool; 77ccc45ea8SJonathan Brassow 78ccc45ea8SJonathan Brassow atomic_t pending_exceptions_count; 79ccc45ea8SJonathan Brassow 80ccc45ea8SJonathan Brassow struct exception_table pending; 81ccc45ea8SJonathan Brassow struct exception_table complete; 82ccc45ea8SJonathan Brassow 83ccc45ea8SJonathan Brassow /* 84ccc45ea8SJonathan Brassow * pe_lock protects all pending_exception operations and access 85ccc45ea8SJonathan Brassow * as well as the snapshot_bios list. 86ccc45ea8SJonathan Brassow */ 87ccc45ea8SJonathan Brassow spinlock_t pe_lock; 88ccc45ea8SJonathan Brassow 89ccc45ea8SJonathan Brassow /* The on disk metadata handler */ 90ccc45ea8SJonathan Brassow struct dm_exception_store *store; 91ccc45ea8SJonathan Brassow 92ccc45ea8SJonathan Brassow struct dm_kcopyd_client *kcopyd_client; 93ccc45ea8SJonathan Brassow 94ccc45ea8SJonathan Brassow /* Queue of snapshot writes for ksnapd to flush */ 95ccc45ea8SJonathan Brassow struct bio_list queued_bios; 96ccc45ea8SJonathan Brassow struct work_struct queued_bios_work; 97ccc45ea8SJonathan Brassow 98ccc45ea8SJonathan Brassow /* Chunks with outstanding reads */ 99ccc45ea8SJonathan Brassow mempool_t *tracked_chunk_pool; 100ccc45ea8SJonathan Brassow spinlock_t tracked_chunk_lock; 101ccc45ea8SJonathan Brassow struct hlist_head tracked_chunk_hash[DM_TRACKED_CHUNK_HASH_SIZE]; 102ccc45ea8SJonathan Brassow }; 103ccc45ea8SJonathan Brassow 104c642f9e0SAdrian Bunk static struct workqueue_struct *ksnapd; 105c4028958SDavid Howells static void flush_queued_bios(struct work_struct *work); 106ca3a931fSAlasdair G Kergon 107ccc45ea8SJonathan Brassow static sector_t chunk_to_sector(struct dm_exception_store *store, 108ccc45ea8SJonathan Brassow chunk_t chunk) 109ccc45ea8SJonathan Brassow { 110ccc45ea8SJonathan Brassow return chunk << store->chunk_shift; 111ccc45ea8SJonathan Brassow } 112ccc45ea8SJonathan Brassow 113ccc45ea8SJonathan Brassow static int bdev_equal(struct block_device *lhs, struct block_device *rhs) 114ccc45ea8SJonathan Brassow { 115ccc45ea8SJonathan Brassow /* 116ccc45ea8SJonathan Brassow * There is only ever one instance of a particular block 117ccc45ea8SJonathan Brassow * device so we can compare pointers safely. 118ccc45ea8SJonathan Brassow */ 119ccc45ea8SJonathan Brassow return lhs == rhs; 120ccc45ea8SJonathan Brassow } 121ccc45ea8SJonathan Brassow 122028867acSAlasdair G Kergon struct dm_snap_pending_exception { 123028867acSAlasdair G Kergon struct dm_snap_exception e; 1241da177e4SLinus Torvalds 1251da177e4SLinus Torvalds /* 1261da177e4SLinus Torvalds * Origin buffers waiting for this to complete are held 1271da177e4SLinus Torvalds * in a bio list 1281da177e4SLinus Torvalds */ 1291da177e4SLinus Torvalds struct bio_list origin_bios; 1301da177e4SLinus Torvalds struct bio_list snapshot_bios; 1311da177e4SLinus Torvalds 1321da177e4SLinus Torvalds /* 133eccf0817SAlasdair G Kergon * Short-term queue of pending exceptions prior to submission. 134eccf0817SAlasdair G Kergon */ 135eccf0817SAlasdair G Kergon struct list_head list; 136eccf0817SAlasdair G Kergon 137eccf0817SAlasdair G Kergon /* 138b4b610f6SAlasdair G Kergon * The primary pending_exception is the one that holds 1394b832e8dSAlasdair G Kergon * the ref_count and the list of origin_bios for a 140b4b610f6SAlasdair G Kergon * group of pending_exceptions. It is always last to get freed. 141b4b610f6SAlasdair G Kergon * These fields get set up when writing to the origin. 1421da177e4SLinus Torvalds */ 143028867acSAlasdair G Kergon struct dm_snap_pending_exception *primary_pe; 144b4b610f6SAlasdair G Kergon 145b4b610f6SAlasdair G Kergon /* 146b4b610f6SAlasdair G Kergon * Number of pending_exceptions processing this chunk. 147b4b610f6SAlasdair G Kergon * When this drops to zero we must complete the origin bios. 148b4b610f6SAlasdair G Kergon * If incrementing or decrementing this, hold pe->snap->lock for 149b4b610f6SAlasdair G Kergon * the sibling concerned and not pe->primary_pe->snap->lock unless 150b4b610f6SAlasdair G Kergon * they are the same. 151b4b610f6SAlasdair G Kergon */ 1524b832e8dSAlasdair G Kergon atomic_t ref_count; 1531da177e4SLinus Torvalds 1541da177e4SLinus Torvalds /* Pointer back to snapshot context */ 1551da177e4SLinus Torvalds struct dm_snapshot *snap; 1561da177e4SLinus Torvalds 1571da177e4SLinus Torvalds /* 1581da177e4SLinus Torvalds * 1 indicates the exception has already been sent to 1591da177e4SLinus Torvalds * kcopyd. 1601da177e4SLinus Torvalds */ 1611da177e4SLinus Torvalds int started; 1621da177e4SLinus Torvalds }; 1631da177e4SLinus Torvalds 1641da177e4SLinus Torvalds /* 1651da177e4SLinus Torvalds * Hash table mapping origin volumes to lists of snapshots and 1661da177e4SLinus Torvalds * a lock to protect it 1671da177e4SLinus Torvalds */ 168e18b890bSChristoph Lameter static struct kmem_cache *exception_cache; 169e18b890bSChristoph Lameter static struct kmem_cache *pending_cache; 1701da177e4SLinus Torvalds 171cd45daffSMikulas Patocka struct dm_snap_tracked_chunk { 172cd45daffSMikulas Patocka struct hlist_node node; 173cd45daffSMikulas Patocka chunk_t chunk; 174cd45daffSMikulas Patocka }; 175cd45daffSMikulas Patocka 176cd45daffSMikulas Patocka static struct kmem_cache *tracked_chunk_cache; 177cd45daffSMikulas Patocka 178cd45daffSMikulas Patocka static struct dm_snap_tracked_chunk *track_chunk(struct dm_snapshot *s, 179cd45daffSMikulas Patocka chunk_t chunk) 180cd45daffSMikulas Patocka { 181cd45daffSMikulas Patocka struct dm_snap_tracked_chunk *c = mempool_alloc(s->tracked_chunk_pool, 182cd45daffSMikulas Patocka GFP_NOIO); 183cd45daffSMikulas Patocka unsigned long flags; 184cd45daffSMikulas Patocka 185cd45daffSMikulas Patocka c->chunk = chunk; 186cd45daffSMikulas Patocka 187cd45daffSMikulas Patocka spin_lock_irqsave(&s->tracked_chunk_lock, flags); 188cd45daffSMikulas Patocka hlist_add_head(&c->node, 189cd45daffSMikulas Patocka &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)]); 190cd45daffSMikulas Patocka spin_unlock_irqrestore(&s->tracked_chunk_lock, flags); 191cd45daffSMikulas Patocka 192cd45daffSMikulas Patocka return c; 193cd45daffSMikulas Patocka } 194cd45daffSMikulas Patocka 195cd45daffSMikulas Patocka static void stop_tracking_chunk(struct dm_snapshot *s, 196cd45daffSMikulas Patocka struct dm_snap_tracked_chunk *c) 197cd45daffSMikulas Patocka { 198cd45daffSMikulas Patocka unsigned long flags; 199cd45daffSMikulas Patocka 200cd45daffSMikulas Patocka spin_lock_irqsave(&s->tracked_chunk_lock, flags); 201cd45daffSMikulas Patocka hlist_del(&c->node); 202cd45daffSMikulas Patocka spin_unlock_irqrestore(&s->tracked_chunk_lock, flags); 203cd45daffSMikulas Patocka 204cd45daffSMikulas Patocka mempool_free(c, s->tracked_chunk_pool); 205cd45daffSMikulas Patocka } 206cd45daffSMikulas Patocka 207a8d41b59SMikulas Patocka static int __chunk_is_tracked(struct dm_snapshot *s, chunk_t chunk) 208a8d41b59SMikulas Patocka { 209a8d41b59SMikulas Patocka struct dm_snap_tracked_chunk *c; 210a8d41b59SMikulas Patocka struct hlist_node *hn; 211a8d41b59SMikulas Patocka int found = 0; 212a8d41b59SMikulas Patocka 213a8d41b59SMikulas Patocka spin_lock_irq(&s->tracked_chunk_lock); 214a8d41b59SMikulas Patocka 215a8d41b59SMikulas Patocka hlist_for_each_entry(c, hn, 216a8d41b59SMikulas Patocka &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)], node) { 217a8d41b59SMikulas Patocka if (c->chunk == chunk) { 218a8d41b59SMikulas Patocka found = 1; 219a8d41b59SMikulas Patocka break; 220a8d41b59SMikulas Patocka } 221a8d41b59SMikulas Patocka } 222a8d41b59SMikulas Patocka 223a8d41b59SMikulas Patocka spin_unlock_irq(&s->tracked_chunk_lock); 224a8d41b59SMikulas Patocka 225a8d41b59SMikulas Patocka return found; 226a8d41b59SMikulas Patocka } 227a8d41b59SMikulas Patocka 2281da177e4SLinus Torvalds /* 2291da177e4SLinus Torvalds * One of these per registered origin, held in the snapshot_origins hash 2301da177e4SLinus Torvalds */ 2311da177e4SLinus Torvalds struct origin { 2321da177e4SLinus Torvalds /* The origin device */ 2331da177e4SLinus Torvalds struct block_device *bdev; 2341da177e4SLinus Torvalds 2351da177e4SLinus Torvalds struct list_head hash_list; 2361da177e4SLinus Torvalds 2371da177e4SLinus Torvalds /* List of snapshots for this origin */ 2381da177e4SLinus Torvalds struct list_head snapshots; 2391da177e4SLinus Torvalds }; 2401da177e4SLinus Torvalds 2411da177e4SLinus Torvalds /* 2421da177e4SLinus Torvalds * Size of the hash table for origin volumes. If we make this 2431da177e4SLinus Torvalds * the size of the minors list then it should be nearly perfect 2441da177e4SLinus Torvalds */ 2451da177e4SLinus Torvalds #define ORIGIN_HASH_SIZE 256 2461da177e4SLinus Torvalds #define ORIGIN_MASK 0xFF 2471da177e4SLinus Torvalds static struct list_head *_origins; 2481da177e4SLinus Torvalds static struct rw_semaphore _origins_lock; 2491da177e4SLinus Torvalds 2501da177e4SLinus Torvalds static int init_origin_hash(void) 2511da177e4SLinus Torvalds { 2521da177e4SLinus Torvalds int i; 2531da177e4SLinus Torvalds 2541da177e4SLinus Torvalds _origins = kmalloc(ORIGIN_HASH_SIZE * sizeof(struct list_head), 2551da177e4SLinus Torvalds GFP_KERNEL); 2561da177e4SLinus Torvalds if (!_origins) { 25772d94861SAlasdair G Kergon DMERR("unable to allocate memory"); 2581da177e4SLinus Torvalds return -ENOMEM; 2591da177e4SLinus Torvalds } 2601da177e4SLinus Torvalds 2611da177e4SLinus Torvalds for (i = 0; i < ORIGIN_HASH_SIZE; i++) 2621da177e4SLinus Torvalds INIT_LIST_HEAD(_origins + i); 2631da177e4SLinus Torvalds init_rwsem(&_origins_lock); 2641da177e4SLinus Torvalds 2651da177e4SLinus Torvalds return 0; 2661da177e4SLinus Torvalds } 2671da177e4SLinus Torvalds 2681da177e4SLinus Torvalds static void exit_origin_hash(void) 2691da177e4SLinus Torvalds { 2701da177e4SLinus Torvalds kfree(_origins); 2711da177e4SLinus Torvalds } 2721da177e4SLinus Torvalds 273028867acSAlasdair G Kergon static unsigned origin_hash(struct block_device *bdev) 2741da177e4SLinus Torvalds { 2751da177e4SLinus Torvalds return bdev->bd_dev & ORIGIN_MASK; 2761da177e4SLinus Torvalds } 2771da177e4SLinus Torvalds 2781da177e4SLinus Torvalds static struct origin *__lookup_origin(struct block_device *origin) 2791da177e4SLinus Torvalds { 2801da177e4SLinus Torvalds struct list_head *ol; 2811da177e4SLinus Torvalds struct origin *o; 2821da177e4SLinus Torvalds 2831da177e4SLinus Torvalds ol = &_origins[origin_hash(origin)]; 2841da177e4SLinus Torvalds list_for_each_entry (o, ol, hash_list) 2851da177e4SLinus Torvalds if (bdev_equal(o->bdev, origin)) 2861da177e4SLinus Torvalds return o; 2871da177e4SLinus Torvalds 2881da177e4SLinus Torvalds return NULL; 2891da177e4SLinus Torvalds } 2901da177e4SLinus Torvalds 2911da177e4SLinus Torvalds static void __insert_origin(struct origin *o) 2921da177e4SLinus Torvalds { 2931da177e4SLinus Torvalds struct list_head *sl = &_origins[origin_hash(o->bdev)]; 2941da177e4SLinus Torvalds list_add_tail(&o->hash_list, sl); 2951da177e4SLinus Torvalds } 2961da177e4SLinus Torvalds 2971da177e4SLinus Torvalds /* 2981da177e4SLinus Torvalds * Make a note of the snapshot and its origin so we can look it 2991da177e4SLinus Torvalds * up when the origin has a write on it. 3001da177e4SLinus Torvalds */ 3011da177e4SLinus Torvalds static int register_snapshot(struct dm_snapshot *snap) 3021da177e4SLinus Torvalds { 30360c856c8SMikulas Patocka struct origin *o, *new_o; 3041da177e4SLinus Torvalds struct block_device *bdev = snap->origin->bdev; 3051da177e4SLinus Torvalds 30660c856c8SMikulas Patocka new_o = kmalloc(sizeof(*new_o), GFP_KERNEL); 30760c856c8SMikulas Patocka if (!new_o) 30860c856c8SMikulas Patocka return -ENOMEM; 30960c856c8SMikulas Patocka 3101da177e4SLinus Torvalds down_write(&_origins_lock); 3111da177e4SLinus Torvalds o = __lookup_origin(bdev); 3121da177e4SLinus Torvalds 31360c856c8SMikulas Patocka if (o) 31460c856c8SMikulas Patocka kfree(new_o); 31560c856c8SMikulas Patocka else { 3161da177e4SLinus Torvalds /* New origin */ 31760c856c8SMikulas Patocka o = new_o; 3181da177e4SLinus Torvalds 3191da177e4SLinus Torvalds /* Initialise the struct */ 3201da177e4SLinus Torvalds INIT_LIST_HEAD(&o->snapshots); 3211da177e4SLinus Torvalds o->bdev = bdev; 3221da177e4SLinus Torvalds 3231da177e4SLinus Torvalds __insert_origin(o); 3241da177e4SLinus Torvalds } 3251da177e4SLinus Torvalds 3261da177e4SLinus Torvalds list_add_tail(&snap->list, &o->snapshots); 3271da177e4SLinus Torvalds 3281da177e4SLinus Torvalds up_write(&_origins_lock); 3291da177e4SLinus Torvalds return 0; 3301da177e4SLinus Torvalds } 3311da177e4SLinus Torvalds 3321da177e4SLinus Torvalds static void unregister_snapshot(struct dm_snapshot *s) 3331da177e4SLinus Torvalds { 3341da177e4SLinus Torvalds struct origin *o; 3351da177e4SLinus Torvalds 3361da177e4SLinus Torvalds down_write(&_origins_lock); 3371da177e4SLinus Torvalds o = __lookup_origin(s->origin->bdev); 3381da177e4SLinus Torvalds 3391da177e4SLinus Torvalds list_del(&s->list); 3401da177e4SLinus Torvalds if (list_empty(&o->snapshots)) { 3411da177e4SLinus Torvalds list_del(&o->hash_list); 3421da177e4SLinus Torvalds kfree(o); 3431da177e4SLinus Torvalds } 3441da177e4SLinus Torvalds 3451da177e4SLinus Torvalds up_write(&_origins_lock); 3461da177e4SLinus Torvalds } 3471da177e4SLinus Torvalds 3481da177e4SLinus Torvalds /* 3491da177e4SLinus Torvalds * Implementation of the exception hash tables. 350d74f81f8SMilan Broz * The lowest hash_shift bits of the chunk number are ignored, allowing 351d74f81f8SMilan Broz * some consecutive chunks to be grouped together. 3521da177e4SLinus Torvalds */ 353d74f81f8SMilan Broz static int init_exception_table(struct exception_table *et, uint32_t size, 354d74f81f8SMilan Broz unsigned hash_shift) 3551da177e4SLinus Torvalds { 3561da177e4SLinus Torvalds unsigned int i; 3571da177e4SLinus Torvalds 358d74f81f8SMilan Broz et->hash_shift = hash_shift; 3591da177e4SLinus Torvalds et->hash_mask = size - 1; 3601da177e4SLinus Torvalds et->table = dm_vcalloc(size, sizeof(struct list_head)); 3611da177e4SLinus Torvalds if (!et->table) 3621da177e4SLinus Torvalds return -ENOMEM; 3631da177e4SLinus Torvalds 3641da177e4SLinus Torvalds for (i = 0; i < size; i++) 3651da177e4SLinus Torvalds INIT_LIST_HEAD(et->table + i); 3661da177e4SLinus Torvalds 3671da177e4SLinus Torvalds return 0; 3681da177e4SLinus Torvalds } 3691da177e4SLinus Torvalds 370e18b890bSChristoph Lameter static void exit_exception_table(struct exception_table *et, struct kmem_cache *mem) 3711da177e4SLinus Torvalds { 3721da177e4SLinus Torvalds struct list_head *slot; 373028867acSAlasdair G Kergon struct dm_snap_exception *ex, *next; 3741da177e4SLinus Torvalds int i, size; 3751da177e4SLinus Torvalds 3761da177e4SLinus Torvalds size = et->hash_mask + 1; 3771da177e4SLinus Torvalds for (i = 0; i < size; i++) { 3781da177e4SLinus Torvalds slot = et->table + i; 3791da177e4SLinus Torvalds 3801da177e4SLinus Torvalds list_for_each_entry_safe (ex, next, slot, hash_list) 3811da177e4SLinus Torvalds kmem_cache_free(mem, ex); 3821da177e4SLinus Torvalds } 3831da177e4SLinus Torvalds 3841da177e4SLinus Torvalds vfree(et->table); 3851da177e4SLinus Torvalds } 3861da177e4SLinus Torvalds 387028867acSAlasdair G Kergon static uint32_t exception_hash(struct exception_table *et, chunk_t chunk) 3881da177e4SLinus Torvalds { 389d74f81f8SMilan Broz return (chunk >> et->hash_shift) & et->hash_mask; 3901da177e4SLinus Torvalds } 3911da177e4SLinus Torvalds 392028867acSAlasdair G Kergon static void insert_exception(struct exception_table *eh, 393028867acSAlasdair G Kergon struct dm_snap_exception *e) 3941da177e4SLinus Torvalds { 3951da177e4SLinus Torvalds struct list_head *l = &eh->table[exception_hash(eh, e->old_chunk)]; 3961da177e4SLinus Torvalds list_add(&e->hash_list, l); 3971da177e4SLinus Torvalds } 3981da177e4SLinus Torvalds 399028867acSAlasdair G Kergon static void remove_exception(struct dm_snap_exception *e) 4001da177e4SLinus Torvalds { 4011da177e4SLinus Torvalds list_del(&e->hash_list); 4021da177e4SLinus Torvalds } 4031da177e4SLinus Torvalds 4041da177e4SLinus Torvalds /* 4051da177e4SLinus Torvalds * Return the exception data for a sector, or NULL if not 4061da177e4SLinus Torvalds * remapped. 4071da177e4SLinus Torvalds */ 408028867acSAlasdair G Kergon static struct dm_snap_exception *lookup_exception(struct exception_table *et, 4091da177e4SLinus Torvalds chunk_t chunk) 4101da177e4SLinus Torvalds { 4111da177e4SLinus Torvalds struct list_head *slot; 412028867acSAlasdair G Kergon struct dm_snap_exception *e; 4131da177e4SLinus Torvalds 4141da177e4SLinus Torvalds slot = &et->table[exception_hash(et, chunk)]; 4151da177e4SLinus Torvalds list_for_each_entry (e, slot, hash_list) 416d74f81f8SMilan Broz if (chunk >= e->old_chunk && 417d74f81f8SMilan Broz chunk <= e->old_chunk + dm_consecutive_chunk_count(e)) 4181da177e4SLinus Torvalds return e; 4191da177e4SLinus Torvalds 4201da177e4SLinus Torvalds return NULL; 4211da177e4SLinus Torvalds } 4221da177e4SLinus Torvalds 423028867acSAlasdair G Kergon static struct dm_snap_exception *alloc_exception(void) 4241da177e4SLinus Torvalds { 425028867acSAlasdair G Kergon struct dm_snap_exception *e; 4261da177e4SLinus Torvalds 4271da177e4SLinus Torvalds e = kmem_cache_alloc(exception_cache, GFP_NOIO); 4281da177e4SLinus Torvalds if (!e) 4291da177e4SLinus Torvalds e = kmem_cache_alloc(exception_cache, GFP_ATOMIC); 4301da177e4SLinus Torvalds 4311da177e4SLinus Torvalds return e; 4321da177e4SLinus Torvalds } 4331da177e4SLinus Torvalds 434028867acSAlasdair G Kergon static void free_exception(struct dm_snap_exception *e) 4351da177e4SLinus Torvalds { 4361da177e4SLinus Torvalds kmem_cache_free(exception_cache, e); 4371da177e4SLinus Torvalds } 4381da177e4SLinus Torvalds 43992e86812SMikulas Patocka static struct dm_snap_pending_exception *alloc_pending_exception(struct dm_snapshot *s) 4401da177e4SLinus Torvalds { 44192e86812SMikulas Patocka struct dm_snap_pending_exception *pe = mempool_alloc(s->pending_pool, 44292e86812SMikulas Patocka GFP_NOIO); 44392e86812SMikulas Patocka 444879129d2SMikulas Patocka atomic_inc(&s->pending_exceptions_count); 44592e86812SMikulas Patocka pe->snap = s; 44692e86812SMikulas Patocka 44792e86812SMikulas Patocka return pe; 4481da177e4SLinus Torvalds } 4491da177e4SLinus Torvalds 450028867acSAlasdair G Kergon static void free_pending_exception(struct dm_snap_pending_exception *pe) 4511da177e4SLinus Torvalds { 452879129d2SMikulas Patocka struct dm_snapshot *s = pe->snap; 453879129d2SMikulas Patocka 454879129d2SMikulas Patocka mempool_free(pe, s->pending_pool); 455879129d2SMikulas Patocka smp_mb__before_atomic_dec(); 456879129d2SMikulas Patocka atomic_dec(&s->pending_exceptions_count); 4571da177e4SLinus Torvalds } 4581da177e4SLinus Torvalds 459d74f81f8SMilan Broz static void insert_completed_exception(struct dm_snapshot *s, 460d74f81f8SMilan Broz struct dm_snap_exception *new_e) 461d74f81f8SMilan Broz { 462d74f81f8SMilan Broz struct exception_table *eh = &s->complete; 463d74f81f8SMilan Broz struct list_head *l; 464d74f81f8SMilan Broz struct dm_snap_exception *e = NULL; 465d74f81f8SMilan Broz 466d74f81f8SMilan Broz l = &eh->table[exception_hash(eh, new_e->old_chunk)]; 467d74f81f8SMilan Broz 468d74f81f8SMilan Broz /* Add immediately if this table doesn't support consecutive chunks */ 469d74f81f8SMilan Broz if (!eh->hash_shift) 470d74f81f8SMilan Broz goto out; 471d74f81f8SMilan Broz 472d74f81f8SMilan Broz /* List is ordered by old_chunk */ 473d74f81f8SMilan Broz list_for_each_entry_reverse(e, l, hash_list) { 474d74f81f8SMilan Broz /* Insert after an existing chunk? */ 475d74f81f8SMilan Broz if (new_e->old_chunk == (e->old_chunk + 476d74f81f8SMilan Broz dm_consecutive_chunk_count(e) + 1) && 477d74f81f8SMilan Broz new_e->new_chunk == (dm_chunk_number(e->new_chunk) + 478d74f81f8SMilan Broz dm_consecutive_chunk_count(e) + 1)) { 479d74f81f8SMilan Broz dm_consecutive_chunk_count_inc(e); 480d74f81f8SMilan Broz free_exception(new_e); 481d74f81f8SMilan Broz return; 482d74f81f8SMilan Broz } 483d74f81f8SMilan Broz 484d74f81f8SMilan Broz /* Insert before an existing chunk? */ 485d74f81f8SMilan Broz if (new_e->old_chunk == (e->old_chunk - 1) && 486d74f81f8SMilan Broz new_e->new_chunk == (dm_chunk_number(e->new_chunk) - 1)) { 487d74f81f8SMilan Broz dm_consecutive_chunk_count_inc(e); 488d74f81f8SMilan Broz e->old_chunk--; 489d74f81f8SMilan Broz e->new_chunk--; 490d74f81f8SMilan Broz free_exception(new_e); 491d74f81f8SMilan Broz return; 492d74f81f8SMilan Broz } 493d74f81f8SMilan Broz 494d74f81f8SMilan Broz if (new_e->old_chunk > e->old_chunk) 495d74f81f8SMilan Broz break; 496d74f81f8SMilan Broz } 497d74f81f8SMilan Broz 498d74f81f8SMilan Broz out: 499d74f81f8SMilan Broz list_add(&new_e->hash_list, e ? &e->hash_list : l); 500d74f81f8SMilan Broz } 501d74f81f8SMilan Broz 502a159c1acSJonathan Brassow /* 503a159c1acSJonathan Brassow * Callback used by the exception stores to load exceptions when 504a159c1acSJonathan Brassow * initialising. 505a159c1acSJonathan Brassow */ 506a159c1acSJonathan Brassow static int dm_add_exception(void *context, chunk_t old, chunk_t new) 5071da177e4SLinus Torvalds { 508a159c1acSJonathan Brassow struct dm_snapshot *s = context; 509028867acSAlasdair G Kergon struct dm_snap_exception *e; 5101da177e4SLinus Torvalds 5111da177e4SLinus Torvalds e = alloc_exception(); 5121da177e4SLinus Torvalds if (!e) 5131da177e4SLinus Torvalds return -ENOMEM; 5141da177e4SLinus Torvalds 5151da177e4SLinus Torvalds e->old_chunk = old; 516d74f81f8SMilan Broz 517d74f81f8SMilan Broz /* Consecutive_count is implicitly initialised to zero */ 5181da177e4SLinus Torvalds e->new_chunk = new; 519d74f81f8SMilan Broz 520d74f81f8SMilan Broz insert_completed_exception(s, e); 521d74f81f8SMilan Broz 5221da177e4SLinus Torvalds return 0; 5231da177e4SLinus Torvalds } 5241da177e4SLinus Torvalds 5251da177e4SLinus Torvalds /* 5261da177e4SLinus Torvalds * Hard coded magic. 5271da177e4SLinus Torvalds */ 5281da177e4SLinus Torvalds static int calc_max_buckets(void) 5291da177e4SLinus Torvalds { 5301da177e4SLinus Torvalds /* use a fixed size of 2MB */ 5311da177e4SLinus Torvalds unsigned long mem = 2 * 1024 * 1024; 5321da177e4SLinus Torvalds mem /= sizeof(struct list_head); 5331da177e4SLinus Torvalds 5341da177e4SLinus Torvalds return mem; 5351da177e4SLinus Torvalds } 5361da177e4SLinus Torvalds 5371da177e4SLinus Torvalds /* 5381da177e4SLinus Torvalds * Allocate room for a suitable hash table. 5391da177e4SLinus Torvalds */ 540fee1998eSJonathan Brassow static int init_hash_tables(struct dm_snapshot *s) 5411da177e4SLinus Torvalds { 5421da177e4SLinus Torvalds sector_t hash_size, cow_dev_size, origin_dev_size, max_buckets; 5431da177e4SLinus Torvalds 5441da177e4SLinus Torvalds /* 5451da177e4SLinus Torvalds * Calculate based on the size of the original volume or 5461da177e4SLinus Torvalds * the COW volume... 5471da177e4SLinus Torvalds */ 548fee1998eSJonathan Brassow cow_dev_size = get_dev_size(s->store->cow->bdev); 5491da177e4SLinus Torvalds origin_dev_size = get_dev_size(s->origin->bdev); 5501da177e4SLinus Torvalds max_buckets = calc_max_buckets(); 5511da177e4SLinus Torvalds 552fee1998eSJonathan Brassow hash_size = min(origin_dev_size, cow_dev_size) >> s->store->chunk_shift; 5531da177e4SLinus Torvalds hash_size = min(hash_size, max_buckets); 5541da177e4SLinus Torvalds 5558defd830SRobert P. J. Day hash_size = rounddown_pow_of_two(hash_size); 556d74f81f8SMilan Broz if (init_exception_table(&s->complete, hash_size, 557d74f81f8SMilan Broz DM_CHUNK_CONSECUTIVE_BITS)) 5581da177e4SLinus Torvalds return -ENOMEM; 5591da177e4SLinus Torvalds 5601da177e4SLinus Torvalds /* 5611da177e4SLinus Torvalds * Allocate hash table for in-flight exceptions 5621da177e4SLinus Torvalds * Make this smaller than the real hash table 5631da177e4SLinus Torvalds */ 5641da177e4SLinus Torvalds hash_size >>= 3; 5651da177e4SLinus Torvalds if (hash_size < 64) 5661da177e4SLinus Torvalds hash_size = 64; 5671da177e4SLinus Torvalds 568d74f81f8SMilan Broz if (init_exception_table(&s->pending, hash_size, 0)) { 5691da177e4SLinus Torvalds exit_exception_table(&s->complete, exception_cache); 5701da177e4SLinus Torvalds return -ENOMEM; 5711da177e4SLinus Torvalds } 5721da177e4SLinus Torvalds 5731da177e4SLinus Torvalds return 0; 5741da177e4SLinus Torvalds } 5751da177e4SLinus Torvalds 5761da177e4SLinus Torvalds /* 5771da177e4SLinus Torvalds * Construct a snapshot mapping: <origin_dev> <COW-dev> <p/n> <chunk-size> 5781da177e4SLinus Torvalds */ 5791da177e4SLinus Torvalds static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv) 5801da177e4SLinus Torvalds { 5811da177e4SLinus Torvalds struct dm_snapshot *s; 582cd45daffSMikulas Patocka int i; 5831da177e4SLinus Torvalds int r = -EINVAL; 5841da177e4SLinus Torvalds char *origin_path; 585fee1998eSJonathan Brassow struct dm_exception_store *store; 586fee1998eSJonathan Brassow unsigned args_used; 5871da177e4SLinus Torvalds 5884c7e3bf4SMark McLoughlin if (argc != 4) { 58972d94861SAlasdair G Kergon ti->error = "requires exactly 4 arguments"; 5901da177e4SLinus Torvalds r = -EINVAL; 591fee1998eSJonathan Brassow goto bad_args; 5921da177e4SLinus Torvalds } 5931da177e4SLinus Torvalds 5941da177e4SLinus Torvalds origin_path = argv[0]; 595fee1998eSJonathan Brassow argv++; 596fee1998eSJonathan Brassow argc--; 5971da177e4SLinus Torvalds 598fee1998eSJonathan Brassow r = dm_exception_store_create(ti, argc, argv, &args_used, &store); 599fee1998eSJonathan Brassow if (r) { 600fee1998eSJonathan Brassow ti->error = "Couldn't create exception store"; 6011da177e4SLinus Torvalds r = -EINVAL; 602fee1998eSJonathan Brassow goto bad_args; 6031da177e4SLinus Torvalds } 6041da177e4SLinus Torvalds 605fee1998eSJonathan Brassow argv += args_used; 606fee1998eSJonathan Brassow argc -= args_used; 607fee1998eSJonathan Brassow 6081da177e4SLinus Torvalds s = kmalloc(sizeof(*s), GFP_KERNEL); 609fee1998eSJonathan Brassow if (!s) { 6101da177e4SLinus Torvalds ti->error = "Cannot allocate snapshot context private " 6111da177e4SLinus Torvalds "structure"; 6121da177e4SLinus Torvalds r = -ENOMEM; 613fee1998eSJonathan Brassow goto bad_snap; 6141da177e4SLinus Torvalds } 6151da177e4SLinus Torvalds 6161da177e4SLinus Torvalds r = dm_get_device(ti, origin_path, 0, ti->len, FMODE_READ, &s->origin); 6171da177e4SLinus Torvalds if (r) { 6181da177e4SLinus Torvalds ti->error = "Cannot get origin device"; 619fee1998eSJonathan Brassow goto bad_origin; 6201da177e4SLinus Torvalds } 6211da177e4SLinus Torvalds 622fee1998eSJonathan Brassow s->store = store; 6231da177e4SLinus Torvalds s->valid = 1; 624aa14edebSAlasdair G Kergon s->active = 0; 625879129d2SMikulas Patocka atomic_set(&s->pending_exceptions_count, 0); 6261da177e4SLinus Torvalds init_rwsem(&s->lock); 627ca3a931fSAlasdair G Kergon spin_lock_init(&s->pe_lock); 6281da177e4SLinus Torvalds 6291da177e4SLinus Torvalds /* Allocate hash table for COW data */ 630fee1998eSJonathan Brassow if (init_hash_tables(s)) { 6311da177e4SLinus Torvalds ti->error = "Unable to allocate hash table space"; 6321da177e4SLinus Torvalds r = -ENOMEM; 633fee1998eSJonathan Brassow goto bad_hash_tables; 6341da177e4SLinus Torvalds } 6351da177e4SLinus Torvalds 636eb69aca5SHeinz Mauelshagen r = dm_kcopyd_client_create(SNAPSHOT_PAGES, &s->kcopyd_client); 6371da177e4SLinus Torvalds if (r) { 6381da177e4SLinus Torvalds ti->error = "Could not create kcopyd client"; 639fee1998eSJonathan Brassow goto bad_kcopyd; 6401da177e4SLinus Torvalds } 6411da177e4SLinus Torvalds 64292e86812SMikulas Patocka s->pending_pool = mempool_create_slab_pool(MIN_IOS, pending_cache); 64392e86812SMikulas Patocka if (!s->pending_pool) { 64492e86812SMikulas Patocka ti->error = "Could not allocate mempool for pending exceptions"; 645fee1998eSJonathan Brassow goto bad_pending_pool; 64692e86812SMikulas Patocka } 64792e86812SMikulas Patocka 648cd45daffSMikulas Patocka s->tracked_chunk_pool = mempool_create_slab_pool(MIN_IOS, 649cd45daffSMikulas Patocka tracked_chunk_cache); 650cd45daffSMikulas Patocka if (!s->tracked_chunk_pool) { 651cd45daffSMikulas Patocka ti->error = "Could not allocate tracked_chunk mempool for " 652cd45daffSMikulas Patocka "tracking reads"; 65392e86812SMikulas Patocka goto bad_tracked_chunk_pool; 654cd45daffSMikulas Patocka } 655cd45daffSMikulas Patocka 656cd45daffSMikulas Patocka for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) 657cd45daffSMikulas Patocka INIT_HLIST_HEAD(&s->tracked_chunk_hash[i]); 658cd45daffSMikulas Patocka 659cd45daffSMikulas Patocka spin_lock_init(&s->tracked_chunk_lock); 660cd45daffSMikulas Patocka 661aa14edebSAlasdair G Kergon /* Metadata must only be loaded into one table at once */ 662493df71cSJonathan Brassow r = s->store->type->read_metadata(s->store, dm_add_exception, 663493df71cSJonathan Brassow (void *)s); 6640764147bSMilan Broz if (r < 0) { 665f9cea4f7SMark McLoughlin ti->error = "Failed to read snapshot metadata"; 666cd45daffSMikulas Patocka goto bad_load_and_register; 6670764147bSMilan Broz } else if (r > 0) { 6680764147bSMilan Broz s->valid = 0; 6690764147bSMilan Broz DMWARN("Snapshot is marked invalid."); 670f9cea4f7SMark McLoughlin } 671aa14edebSAlasdair G Kergon 672ca3a931fSAlasdair G Kergon bio_list_init(&s->queued_bios); 673c4028958SDavid Howells INIT_WORK(&s->queued_bios_work, flush_queued_bios); 674ca3a931fSAlasdair G Kergon 6751da177e4SLinus Torvalds /* Add snapshot to the list of snapshots for this origin */ 676aa14edebSAlasdair G Kergon /* Exceptions aren't triggered till snapshot_resume() is called */ 6771da177e4SLinus Torvalds if (register_snapshot(s)) { 6781da177e4SLinus Torvalds r = -EINVAL; 6791da177e4SLinus Torvalds ti->error = "Cannot register snapshot origin"; 680cd45daffSMikulas Patocka goto bad_load_and_register; 6811da177e4SLinus Torvalds } 6821da177e4SLinus Torvalds 6831da177e4SLinus Torvalds ti->private = s; 684d0216849SJonathan Brassow ti->split_io = s->store->chunk_size; 6851da177e4SLinus Torvalds 6861da177e4SLinus Torvalds return 0; 6871da177e4SLinus Torvalds 688cd45daffSMikulas Patocka bad_load_and_register: 689cd45daffSMikulas Patocka mempool_destroy(s->tracked_chunk_pool); 690cd45daffSMikulas Patocka 69192e86812SMikulas Patocka bad_tracked_chunk_pool: 69292e86812SMikulas Patocka mempool_destroy(s->pending_pool); 69392e86812SMikulas Patocka 694fee1998eSJonathan Brassow bad_pending_pool: 695eb69aca5SHeinz Mauelshagen dm_kcopyd_client_destroy(s->kcopyd_client); 6961da177e4SLinus Torvalds 697fee1998eSJonathan Brassow bad_kcopyd: 6981da177e4SLinus Torvalds exit_exception_table(&s->pending, pending_cache); 6991da177e4SLinus Torvalds exit_exception_table(&s->complete, exception_cache); 7001da177e4SLinus Torvalds 701fee1998eSJonathan Brassow bad_hash_tables: 7021da177e4SLinus Torvalds dm_put_device(ti, s->origin); 7031da177e4SLinus Torvalds 704fee1998eSJonathan Brassow bad_origin: 7051da177e4SLinus Torvalds kfree(s); 7061da177e4SLinus Torvalds 707fee1998eSJonathan Brassow bad_snap: 708fee1998eSJonathan Brassow dm_exception_store_destroy(store); 709fee1998eSJonathan Brassow 710fee1998eSJonathan Brassow bad_args: 7111da177e4SLinus Torvalds return r; 7121da177e4SLinus Torvalds } 7131da177e4SLinus Torvalds 71431c93a0cSMilan Broz static void __free_exceptions(struct dm_snapshot *s) 71531c93a0cSMilan Broz { 716eb69aca5SHeinz Mauelshagen dm_kcopyd_client_destroy(s->kcopyd_client); 71731c93a0cSMilan Broz s->kcopyd_client = NULL; 71831c93a0cSMilan Broz 71931c93a0cSMilan Broz exit_exception_table(&s->pending, pending_cache); 72031c93a0cSMilan Broz exit_exception_table(&s->complete, exception_cache); 72131c93a0cSMilan Broz } 72231c93a0cSMilan Broz 7231da177e4SLinus Torvalds static void snapshot_dtr(struct dm_target *ti) 7241da177e4SLinus Torvalds { 725cd45daffSMikulas Patocka #ifdef CONFIG_DM_DEBUG 726cd45daffSMikulas Patocka int i; 727cd45daffSMikulas Patocka #endif 728028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 7291da177e4SLinus Torvalds 730ca3a931fSAlasdair G Kergon flush_workqueue(ksnapd); 731ca3a931fSAlasdair G Kergon 732138728dcSAlasdair G Kergon /* Prevent further origin writes from using this snapshot. */ 733138728dcSAlasdair G Kergon /* After this returns there can be no new kcopyd jobs. */ 7341da177e4SLinus Torvalds unregister_snapshot(s); 7351da177e4SLinus Torvalds 736879129d2SMikulas Patocka while (atomic_read(&s->pending_exceptions_count)) 73790fa1527SMikulas Patocka msleep(1); 738879129d2SMikulas Patocka /* 739879129d2SMikulas Patocka * Ensure instructions in mempool_destroy aren't reordered 740879129d2SMikulas Patocka * before atomic_read. 741879129d2SMikulas Patocka */ 742879129d2SMikulas Patocka smp_mb(); 743879129d2SMikulas Patocka 744cd45daffSMikulas Patocka #ifdef CONFIG_DM_DEBUG 745cd45daffSMikulas Patocka for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) 746cd45daffSMikulas Patocka BUG_ON(!hlist_empty(&s->tracked_chunk_hash[i])); 747cd45daffSMikulas Patocka #endif 748cd45daffSMikulas Patocka 749cd45daffSMikulas Patocka mempool_destroy(s->tracked_chunk_pool); 750cd45daffSMikulas Patocka 75131c93a0cSMilan Broz __free_exceptions(s); 7521da177e4SLinus Torvalds 75392e86812SMikulas Patocka mempool_destroy(s->pending_pool); 75492e86812SMikulas Patocka 7551da177e4SLinus Torvalds dm_put_device(ti, s->origin); 756fee1998eSJonathan Brassow 757fee1998eSJonathan Brassow dm_exception_store_destroy(s->store); 758138728dcSAlasdair G Kergon 7591da177e4SLinus Torvalds kfree(s); 7601da177e4SLinus Torvalds } 7611da177e4SLinus Torvalds 7621da177e4SLinus Torvalds /* 7631da177e4SLinus Torvalds * Flush a list of buffers. 7641da177e4SLinus Torvalds */ 7651da177e4SLinus Torvalds static void flush_bios(struct bio *bio) 7661da177e4SLinus Torvalds { 7671da177e4SLinus Torvalds struct bio *n; 7681da177e4SLinus Torvalds 7691da177e4SLinus Torvalds while (bio) { 7701da177e4SLinus Torvalds n = bio->bi_next; 7711da177e4SLinus Torvalds bio->bi_next = NULL; 7721da177e4SLinus Torvalds generic_make_request(bio); 7731da177e4SLinus Torvalds bio = n; 7741da177e4SLinus Torvalds } 7751da177e4SLinus Torvalds } 7761da177e4SLinus Torvalds 777c4028958SDavid Howells static void flush_queued_bios(struct work_struct *work) 778ca3a931fSAlasdair G Kergon { 779c4028958SDavid Howells struct dm_snapshot *s = 780c4028958SDavid Howells container_of(work, struct dm_snapshot, queued_bios_work); 781ca3a931fSAlasdair G Kergon struct bio *queued_bios; 782ca3a931fSAlasdair G Kergon unsigned long flags; 783ca3a931fSAlasdair G Kergon 784ca3a931fSAlasdair G Kergon spin_lock_irqsave(&s->pe_lock, flags); 785ca3a931fSAlasdair G Kergon queued_bios = bio_list_get(&s->queued_bios); 786ca3a931fSAlasdair G Kergon spin_unlock_irqrestore(&s->pe_lock, flags); 787ca3a931fSAlasdair G Kergon 788ca3a931fSAlasdair G Kergon flush_bios(queued_bios); 789ca3a931fSAlasdair G Kergon } 790ca3a931fSAlasdair G Kergon 7911da177e4SLinus Torvalds /* 7921da177e4SLinus Torvalds * Error a list of buffers. 7931da177e4SLinus Torvalds */ 7941da177e4SLinus Torvalds static void error_bios(struct bio *bio) 7951da177e4SLinus Torvalds { 7961da177e4SLinus Torvalds struct bio *n; 7971da177e4SLinus Torvalds 7981da177e4SLinus Torvalds while (bio) { 7991da177e4SLinus Torvalds n = bio->bi_next; 8001da177e4SLinus Torvalds bio->bi_next = NULL; 8016712ecf8SNeilBrown bio_io_error(bio); 8021da177e4SLinus Torvalds bio = n; 8031da177e4SLinus Torvalds } 8041da177e4SLinus Torvalds } 8051da177e4SLinus Torvalds 806695368acSAlasdair G Kergon static void __invalidate_snapshot(struct dm_snapshot *s, int err) 80776df1c65SAlasdair G Kergon { 80876df1c65SAlasdair G Kergon if (!s->valid) 80976df1c65SAlasdair G Kergon return; 81076df1c65SAlasdair G Kergon 81176df1c65SAlasdair G Kergon if (err == -EIO) 81276df1c65SAlasdair G Kergon DMERR("Invalidating snapshot: Error reading/writing."); 81376df1c65SAlasdair G Kergon else if (err == -ENOMEM) 81476df1c65SAlasdair G Kergon DMERR("Invalidating snapshot: Unable to allocate exception."); 81576df1c65SAlasdair G Kergon 816493df71cSJonathan Brassow if (s->store->type->drop_snapshot) 817493df71cSJonathan Brassow s->store->type->drop_snapshot(s->store); 81876df1c65SAlasdair G Kergon 81976df1c65SAlasdair G Kergon s->valid = 0; 82076df1c65SAlasdair G Kergon 8210cea9c78SJonathan Brassow dm_table_event(s->store->ti->table); 82276df1c65SAlasdair G Kergon } 82376df1c65SAlasdair G Kergon 824028867acSAlasdair G Kergon static void get_pending_exception(struct dm_snap_pending_exception *pe) 8254b832e8dSAlasdair G Kergon { 8264b832e8dSAlasdair G Kergon atomic_inc(&pe->ref_count); 8274b832e8dSAlasdair G Kergon } 8284b832e8dSAlasdair G Kergon 829028867acSAlasdair G Kergon static struct bio *put_pending_exception(struct dm_snap_pending_exception *pe) 8304b832e8dSAlasdair G Kergon { 831028867acSAlasdair G Kergon struct dm_snap_pending_exception *primary_pe; 8324b832e8dSAlasdair G Kergon struct bio *origin_bios = NULL; 8334b832e8dSAlasdair G Kergon 8344b832e8dSAlasdair G Kergon primary_pe = pe->primary_pe; 8354b832e8dSAlasdair G Kergon 8364b832e8dSAlasdair G Kergon /* 8374b832e8dSAlasdair G Kergon * If this pe is involved in a write to the origin and 8384b832e8dSAlasdair G Kergon * it is the last sibling to complete then release 8394b832e8dSAlasdair G Kergon * the bios for the original write to the origin. 8404b832e8dSAlasdair G Kergon */ 8414b832e8dSAlasdair G Kergon if (primary_pe && 8427c5f78b9SMikulas Patocka atomic_dec_and_test(&primary_pe->ref_count)) { 8434b832e8dSAlasdair G Kergon origin_bios = bio_list_get(&primary_pe->origin_bios); 8447c5f78b9SMikulas Patocka free_pending_exception(primary_pe); 8457c5f78b9SMikulas Patocka } 8464b832e8dSAlasdair G Kergon 8474b832e8dSAlasdair G Kergon /* 8484b832e8dSAlasdair G Kergon * Free the pe if it's not linked to an origin write or if 8494b832e8dSAlasdair G Kergon * it's not itself a primary pe. 8504b832e8dSAlasdair G Kergon */ 8514b832e8dSAlasdair G Kergon if (!primary_pe || primary_pe != pe) 8524b832e8dSAlasdair G Kergon free_pending_exception(pe); 8534b832e8dSAlasdair G Kergon 8544b832e8dSAlasdair G Kergon return origin_bios; 8554b832e8dSAlasdair G Kergon } 8564b832e8dSAlasdair G Kergon 857028867acSAlasdair G Kergon static void pending_complete(struct dm_snap_pending_exception *pe, int success) 8581da177e4SLinus Torvalds { 859028867acSAlasdair G Kergon struct dm_snap_exception *e; 8601da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 8619d493fa8SAlasdair G Kergon struct bio *origin_bios = NULL; 8629d493fa8SAlasdair G Kergon struct bio *snapshot_bios = NULL; 8639d493fa8SAlasdair G Kergon int error = 0; 8641da177e4SLinus Torvalds 86576df1c65SAlasdair G Kergon if (!success) { 86676df1c65SAlasdair G Kergon /* Read/write error - snapshot is unusable */ 8671da177e4SLinus Torvalds down_write(&s->lock); 868695368acSAlasdair G Kergon __invalidate_snapshot(s, -EIO); 8699d493fa8SAlasdair G Kergon error = 1; 87076df1c65SAlasdair G Kergon goto out; 87176df1c65SAlasdair G Kergon } 87276df1c65SAlasdair G Kergon 87376df1c65SAlasdair G Kergon e = alloc_exception(); 87476df1c65SAlasdair G Kergon if (!e) { 87576df1c65SAlasdair G Kergon down_write(&s->lock); 876695368acSAlasdair G Kergon __invalidate_snapshot(s, -ENOMEM); 8779d493fa8SAlasdair G Kergon error = 1; 8781da177e4SLinus Torvalds goto out; 8791da177e4SLinus Torvalds } 8801da177e4SLinus Torvalds *e = pe->e; 8811da177e4SLinus Torvalds 8829d493fa8SAlasdair G Kergon down_write(&s->lock); 8839d493fa8SAlasdair G Kergon if (!s->valid) { 8849d493fa8SAlasdair G Kergon free_exception(e); 8859d493fa8SAlasdair G Kergon error = 1; 8869d493fa8SAlasdair G Kergon goto out; 8879d493fa8SAlasdair G Kergon } 8889d493fa8SAlasdair G Kergon 8891da177e4SLinus Torvalds /* 890a8d41b59SMikulas Patocka * Check for conflicting reads. This is extremely improbable, 89190fa1527SMikulas Patocka * so msleep(1) is sufficient and there is no need for a wait queue. 892a8d41b59SMikulas Patocka */ 893a8d41b59SMikulas Patocka while (__chunk_is_tracked(s, pe->e.old_chunk)) 89490fa1527SMikulas Patocka msleep(1); 895a8d41b59SMikulas Patocka 896a8d41b59SMikulas Patocka /* 8971da177e4SLinus Torvalds * Add a proper exception, and remove the 8981da177e4SLinus Torvalds * in-flight exception from the list. 8991da177e4SLinus Torvalds */ 900d74f81f8SMilan Broz insert_completed_exception(s, e); 9011da177e4SLinus Torvalds 9021da177e4SLinus Torvalds out: 903695368acSAlasdair G Kergon remove_exception(&pe->e); 9049d493fa8SAlasdair G Kergon snapshot_bios = bio_list_get(&pe->snapshot_bios); 9054b832e8dSAlasdair G Kergon origin_bios = put_pending_exception(pe); 906b4b610f6SAlasdair G Kergon 9079d493fa8SAlasdair G Kergon up_write(&s->lock); 9089d493fa8SAlasdair G Kergon 9099d493fa8SAlasdair G Kergon /* Submit any pending write bios */ 9109d493fa8SAlasdair G Kergon if (error) 9119d493fa8SAlasdair G Kergon error_bios(snapshot_bios); 9129d493fa8SAlasdair G Kergon else 9139d493fa8SAlasdair G Kergon flush_bios(snapshot_bios); 9149d493fa8SAlasdair G Kergon 9159d493fa8SAlasdair G Kergon flush_bios(origin_bios); 9161da177e4SLinus Torvalds } 9171da177e4SLinus Torvalds 9181da177e4SLinus Torvalds static void commit_callback(void *context, int success) 9191da177e4SLinus Torvalds { 920028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = context; 921028867acSAlasdair G Kergon 9221da177e4SLinus Torvalds pending_complete(pe, success); 9231da177e4SLinus Torvalds } 9241da177e4SLinus Torvalds 9251da177e4SLinus Torvalds /* 9261da177e4SLinus Torvalds * Called when the copy I/O has finished. kcopyd actually runs 9271da177e4SLinus Torvalds * this code so don't block. 9281da177e4SLinus Torvalds */ 9294cdc1d1fSAlasdair G Kergon static void copy_callback(int read_err, unsigned long write_err, void *context) 9301da177e4SLinus Torvalds { 931028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = context; 9321da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 9331da177e4SLinus Torvalds 9341da177e4SLinus Torvalds if (read_err || write_err) 9351da177e4SLinus Torvalds pending_complete(pe, 0); 9361da177e4SLinus Torvalds 9371da177e4SLinus Torvalds else 9381da177e4SLinus Torvalds /* Update the metadata if we are persistent */ 939493df71cSJonathan Brassow s->store->type->commit_exception(s->store, &pe->e, 940b2a11465SJonathan Brassow commit_callback, pe); 9411da177e4SLinus Torvalds } 9421da177e4SLinus Torvalds 9431da177e4SLinus Torvalds /* 9441da177e4SLinus Torvalds * Dispatches the copy operation to kcopyd. 9451da177e4SLinus Torvalds */ 946028867acSAlasdair G Kergon static void start_copy(struct dm_snap_pending_exception *pe) 9471da177e4SLinus Torvalds { 9481da177e4SLinus Torvalds struct dm_snapshot *s = pe->snap; 94922a1ceb1SHeinz Mauelshagen struct dm_io_region src, dest; 9501da177e4SLinus Torvalds struct block_device *bdev = s->origin->bdev; 9511da177e4SLinus Torvalds sector_t dev_size; 9521da177e4SLinus Torvalds 9531da177e4SLinus Torvalds dev_size = get_dev_size(bdev); 9541da177e4SLinus Torvalds 9551da177e4SLinus Torvalds src.bdev = bdev; 95671fab00aSJonathan Brassow src.sector = chunk_to_sector(s->store, pe->e.old_chunk); 957d0216849SJonathan Brassow src.count = min(s->store->chunk_size, dev_size - src.sector); 9581da177e4SLinus Torvalds 95949beb2b8SJonathan Brassow dest.bdev = s->store->cow->bdev; 96071fab00aSJonathan Brassow dest.sector = chunk_to_sector(s->store, pe->e.new_chunk); 9611da177e4SLinus Torvalds dest.count = src.count; 9621da177e4SLinus Torvalds 9631da177e4SLinus Torvalds /* Hand over to kcopyd */ 964eb69aca5SHeinz Mauelshagen dm_kcopyd_copy(s->kcopyd_client, 9651da177e4SLinus Torvalds &src, 1, &dest, 0, copy_callback, pe); 9661da177e4SLinus Torvalds } 9671da177e4SLinus Torvalds 9682913808eSMikulas Patocka static struct dm_snap_pending_exception * 9692913808eSMikulas Patocka __lookup_pending_exception(struct dm_snapshot *s, chunk_t chunk) 9702913808eSMikulas Patocka { 9712913808eSMikulas Patocka struct dm_snap_exception *e = lookup_exception(&s->pending, chunk); 9722913808eSMikulas Patocka 9732913808eSMikulas Patocka if (!e) 9742913808eSMikulas Patocka return NULL; 9752913808eSMikulas Patocka 9762913808eSMikulas Patocka return container_of(e, struct dm_snap_pending_exception, e); 9772913808eSMikulas Patocka } 9782913808eSMikulas Patocka 9791da177e4SLinus Torvalds /* 9801da177e4SLinus Torvalds * Looks to see if this snapshot already has a pending exception 9811da177e4SLinus Torvalds * for this chunk, otherwise it allocates a new one and inserts 9821da177e4SLinus Torvalds * it into the pending table. 9831da177e4SLinus Torvalds * 9841da177e4SLinus Torvalds * NOTE: a write lock must be held on snap->lock before calling 9851da177e4SLinus Torvalds * this. 9861da177e4SLinus Torvalds */ 987028867acSAlasdair G Kergon static struct dm_snap_pending_exception * 988c6621392SMikulas Patocka __find_pending_exception(struct dm_snapshot *s, 989c6621392SMikulas Patocka struct dm_snap_pending_exception *pe, chunk_t chunk) 9901da177e4SLinus Torvalds { 991c6621392SMikulas Patocka struct dm_snap_pending_exception *pe2; 99276df1c65SAlasdair G Kergon 9932913808eSMikulas Patocka pe2 = __lookup_pending_exception(s, chunk); 9942913808eSMikulas Patocka if (pe2) { 9951da177e4SLinus Torvalds free_pending_exception(pe); 9962913808eSMikulas Patocka return pe2; 99776df1c65SAlasdair G Kergon } 99876df1c65SAlasdair G Kergon 9991da177e4SLinus Torvalds pe->e.old_chunk = chunk; 10001da177e4SLinus Torvalds bio_list_init(&pe->origin_bios); 10011da177e4SLinus Torvalds bio_list_init(&pe->snapshot_bios); 1002b4b610f6SAlasdair G Kergon pe->primary_pe = NULL; 10034b832e8dSAlasdair G Kergon atomic_set(&pe->ref_count, 0); 10041da177e4SLinus Torvalds pe->started = 0; 10051da177e4SLinus Torvalds 1006493df71cSJonathan Brassow if (s->store->type->prepare_exception(s->store, &pe->e)) { 10071da177e4SLinus Torvalds free_pending_exception(pe); 10081da177e4SLinus Torvalds return NULL; 10091da177e4SLinus Torvalds } 10101da177e4SLinus Torvalds 10114b832e8dSAlasdair G Kergon get_pending_exception(pe); 10121da177e4SLinus Torvalds insert_exception(&s->pending, &pe->e); 10131da177e4SLinus Torvalds 10141da177e4SLinus Torvalds return pe; 10151da177e4SLinus Torvalds } 10161da177e4SLinus Torvalds 1017028867acSAlasdair G Kergon static void remap_exception(struct dm_snapshot *s, struct dm_snap_exception *e, 1018d74f81f8SMilan Broz struct bio *bio, chunk_t chunk) 10191da177e4SLinus Torvalds { 102049beb2b8SJonathan Brassow bio->bi_bdev = s->store->cow->bdev; 102171fab00aSJonathan Brassow bio->bi_sector = chunk_to_sector(s->store, 102271fab00aSJonathan Brassow dm_chunk_number(e->new_chunk) + 1023d74f81f8SMilan Broz (chunk - e->old_chunk)) + 102471fab00aSJonathan Brassow (bio->bi_sector & 102571fab00aSJonathan Brassow s->store->chunk_mask); 10261da177e4SLinus Torvalds } 10271da177e4SLinus Torvalds 10281da177e4SLinus Torvalds static int snapshot_map(struct dm_target *ti, struct bio *bio, 10291da177e4SLinus Torvalds union map_info *map_context) 10301da177e4SLinus Torvalds { 1031028867acSAlasdair G Kergon struct dm_snap_exception *e; 1032028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 1033d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED; 10341da177e4SLinus Torvalds chunk_t chunk; 1035028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe = NULL; 10361da177e4SLinus Torvalds 103771fab00aSJonathan Brassow chunk = sector_to_chunk(s->store, bio->bi_sector); 10381da177e4SLinus Torvalds 10391da177e4SLinus Torvalds /* Full snapshots are not usable */ 104076df1c65SAlasdair G Kergon /* To get here the table must be live so s->active is always set. */ 10411da177e4SLinus Torvalds if (!s->valid) 1042f6a80ea8SAlasdair G Kergon return -EIO; 10431da177e4SLinus Torvalds 10441da177e4SLinus Torvalds /* FIXME: should only take write lock if we need 10451da177e4SLinus Torvalds * to copy an exception */ 10461da177e4SLinus Torvalds down_write(&s->lock); 10471da177e4SLinus Torvalds 104876df1c65SAlasdair G Kergon if (!s->valid) { 104976df1c65SAlasdair G Kergon r = -EIO; 105076df1c65SAlasdair G Kergon goto out_unlock; 105176df1c65SAlasdair G Kergon } 105276df1c65SAlasdair G Kergon 10531da177e4SLinus Torvalds /* If the block is already remapped - use that, else remap it */ 10541da177e4SLinus Torvalds e = lookup_exception(&s->complete, chunk); 10551da177e4SLinus Torvalds if (e) { 1056d74f81f8SMilan Broz remap_exception(s, e, bio, chunk); 105776df1c65SAlasdair G Kergon goto out_unlock; 105876df1c65SAlasdair G Kergon } 10591da177e4SLinus Torvalds 1060ba40a2aaSAlasdair G Kergon /* 1061ba40a2aaSAlasdair G Kergon * Write to snapshot - higher level takes care of RW/RO 1062ba40a2aaSAlasdair G Kergon * flags so we should only get this if we are 1063ba40a2aaSAlasdair G Kergon * writeable. 1064ba40a2aaSAlasdair G Kergon */ 1065ba40a2aaSAlasdair G Kergon if (bio_rw(bio) == WRITE) { 10662913808eSMikulas Patocka pe = __lookup_pending_exception(s, chunk); 10672913808eSMikulas Patocka if (!pe) { 1068c6621392SMikulas Patocka up_write(&s->lock); 1069c6621392SMikulas Patocka pe = alloc_pending_exception(s); 1070c6621392SMikulas Patocka down_write(&s->lock); 1071c6621392SMikulas Patocka 1072c6621392SMikulas Patocka if (!s->valid) { 1073c6621392SMikulas Patocka free_pending_exception(pe); 1074c6621392SMikulas Patocka r = -EIO; 1075c6621392SMikulas Patocka goto out_unlock; 1076c6621392SMikulas Patocka } 1077c6621392SMikulas Patocka 107835bf659bSMikulas Patocka e = lookup_exception(&s->complete, chunk); 107935bf659bSMikulas Patocka if (e) { 108035bf659bSMikulas Patocka free_pending_exception(pe); 108135bf659bSMikulas Patocka remap_exception(s, e, bio, chunk); 108235bf659bSMikulas Patocka goto out_unlock; 108335bf659bSMikulas Patocka } 108435bf659bSMikulas Patocka 1085c6621392SMikulas Patocka pe = __find_pending_exception(s, pe, chunk); 10861da177e4SLinus Torvalds if (!pe) { 1087695368acSAlasdair G Kergon __invalidate_snapshot(s, -ENOMEM); 10881da177e4SLinus Torvalds r = -EIO; 108976df1c65SAlasdair G Kergon goto out_unlock; 109076df1c65SAlasdair G Kergon } 10912913808eSMikulas Patocka } 109276df1c65SAlasdair G Kergon 1093d74f81f8SMilan Broz remap_exception(s, &pe->e, bio, chunk); 10941da177e4SLinus Torvalds bio_list_add(&pe->snapshot_bios, bio); 10951da177e4SLinus Torvalds 1096d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 1097ba40a2aaSAlasdair G Kergon 10981da177e4SLinus Torvalds if (!pe->started) { 10991da177e4SLinus Torvalds /* this is protected by snap->lock */ 11001da177e4SLinus Torvalds pe->started = 1; 110176df1c65SAlasdair G Kergon up_write(&s->lock); 110276df1c65SAlasdair G Kergon start_copy(pe); 1103ba40a2aaSAlasdair G Kergon goto out; 1104ba40a2aaSAlasdair G Kergon } 1105cd45daffSMikulas Patocka } else { 11061da177e4SLinus Torvalds bio->bi_bdev = s->origin->bdev; 1107cd45daffSMikulas Patocka map_context->ptr = track_chunk(s, chunk); 1108cd45daffSMikulas Patocka } 11091da177e4SLinus Torvalds 1110ba40a2aaSAlasdair G Kergon out_unlock: 1111ba40a2aaSAlasdair G Kergon up_write(&s->lock); 1112ba40a2aaSAlasdair G Kergon out: 11131da177e4SLinus Torvalds return r; 11141da177e4SLinus Torvalds } 11151da177e4SLinus Torvalds 1116cd45daffSMikulas Patocka static int snapshot_end_io(struct dm_target *ti, struct bio *bio, 1117cd45daffSMikulas Patocka int error, union map_info *map_context) 1118cd45daffSMikulas Patocka { 1119cd45daffSMikulas Patocka struct dm_snapshot *s = ti->private; 1120cd45daffSMikulas Patocka struct dm_snap_tracked_chunk *c = map_context->ptr; 1121cd45daffSMikulas Patocka 1122cd45daffSMikulas Patocka if (c) 1123cd45daffSMikulas Patocka stop_tracking_chunk(s, c); 1124cd45daffSMikulas Patocka 1125cd45daffSMikulas Patocka return 0; 1126cd45daffSMikulas Patocka } 1127cd45daffSMikulas Patocka 11281da177e4SLinus Torvalds static void snapshot_resume(struct dm_target *ti) 11291da177e4SLinus Torvalds { 1130028867acSAlasdair G Kergon struct dm_snapshot *s = ti->private; 11311da177e4SLinus Torvalds 1132aa14edebSAlasdair G Kergon down_write(&s->lock); 1133aa14edebSAlasdair G Kergon s->active = 1; 1134aa14edebSAlasdair G Kergon up_write(&s->lock); 11351da177e4SLinus Torvalds } 11361da177e4SLinus Torvalds 11371da177e4SLinus Torvalds static int snapshot_status(struct dm_target *ti, status_type_t type, 11381da177e4SLinus Torvalds char *result, unsigned int maxlen) 11391da177e4SLinus Torvalds { 11402e4a31dfSJonathan Brassow unsigned sz = 0; 1141028867acSAlasdair G Kergon struct dm_snapshot *snap = ti->private; 11421da177e4SLinus Torvalds 11431da177e4SLinus Torvalds switch (type) { 11441da177e4SLinus Torvalds case STATUSTYPE_INFO: 11451da177e4SLinus Torvalds if (!snap->valid) 11462e4a31dfSJonathan Brassow DMEMIT("Invalid"); 11471da177e4SLinus Torvalds else { 1148493df71cSJonathan Brassow if (snap->store->type->fraction_full) { 11491da177e4SLinus Torvalds sector_t numerator, denominator; 1150493df71cSJonathan Brassow snap->store->type->fraction_full(snap->store, 11511da177e4SLinus Torvalds &numerator, 11521da177e4SLinus Torvalds &denominator); 11532e4a31dfSJonathan Brassow DMEMIT("%llu/%llu", 11544ee218cdSAndrew Morton (unsigned long long)numerator, 11554ee218cdSAndrew Morton (unsigned long long)denominator); 11561da177e4SLinus Torvalds } 11571da177e4SLinus Torvalds else 11582e4a31dfSJonathan Brassow DMEMIT("Unknown"); 11591da177e4SLinus Torvalds } 11601da177e4SLinus Torvalds break; 11611da177e4SLinus Torvalds 11621da177e4SLinus Torvalds case STATUSTYPE_TABLE: 11631da177e4SLinus Torvalds /* 11641da177e4SLinus Torvalds * kdevname returns a static pointer so we need 11651da177e4SLinus Torvalds * to make private copies if the output is to 11661da177e4SLinus Torvalds * make sense. 11671da177e4SLinus Torvalds */ 11682e4a31dfSJonathan Brassow DMEMIT("%s", snap->origin->name); 11692e4a31dfSJonathan Brassow DMEMIT(" %s %s %llu", snap->store->cow->name, 1170493df71cSJonathan Brassow snap->store->type->name, 1171d0216849SJonathan Brassow (unsigned long long)snap->store->chunk_size); 11721da177e4SLinus Torvalds break; 11731da177e4SLinus Torvalds } 11741da177e4SLinus Torvalds 11751da177e4SLinus Torvalds return 0; 11761da177e4SLinus Torvalds } 11771da177e4SLinus Torvalds 11781da177e4SLinus Torvalds /*----------------------------------------------------------------- 11791da177e4SLinus Torvalds * Origin methods 11801da177e4SLinus Torvalds *---------------------------------------------------------------*/ 11811da177e4SLinus Torvalds static int __origin_write(struct list_head *snapshots, struct bio *bio) 11821da177e4SLinus Torvalds { 1183d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED, first = 0; 11841da177e4SLinus Torvalds struct dm_snapshot *snap; 1185028867acSAlasdair G Kergon struct dm_snap_exception *e; 1186028867acSAlasdair G Kergon struct dm_snap_pending_exception *pe, *next_pe, *primary_pe = NULL; 11871da177e4SLinus Torvalds chunk_t chunk; 1188eccf0817SAlasdair G Kergon LIST_HEAD(pe_queue); 11891da177e4SLinus Torvalds 11901da177e4SLinus Torvalds /* Do all the snapshots on this origin */ 11911da177e4SLinus Torvalds list_for_each_entry (snap, snapshots, list) { 11921da177e4SLinus Torvalds 119376df1c65SAlasdair G Kergon down_write(&snap->lock); 119476df1c65SAlasdair G Kergon 1195aa14edebSAlasdair G Kergon /* Only deal with valid and active snapshots */ 1196aa14edebSAlasdair G Kergon if (!snap->valid || !snap->active) 119776df1c65SAlasdair G Kergon goto next_snapshot; 11981da177e4SLinus Torvalds 1199d5e404c1SAlasdair G Kergon /* Nothing to do if writing beyond end of snapshot */ 12000cea9c78SJonathan Brassow if (bio->bi_sector >= dm_table_get_size(snap->store->ti->table)) 120176df1c65SAlasdair G Kergon goto next_snapshot; 12021da177e4SLinus Torvalds 12031da177e4SLinus Torvalds /* 12041da177e4SLinus Torvalds * Remember, different snapshots can have 12051da177e4SLinus Torvalds * different chunk sizes. 12061da177e4SLinus Torvalds */ 120771fab00aSJonathan Brassow chunk = sector_to_chunk(snap->store, bio->bi_sector); 12081da177e4SLinus Torvalds 12091da177e4SLinus Torvalds /* 12101da177e4SLinus Torvalds * Check exception table to see if block 12111da177e4SLinus Torvalds * is already remapped in this snapshot 12121da177e4SLinus Torvalds * and trigger an exception if not. 1213b4b610f6SAlasdair G Kergon * 12144b832e8dSAlasdair G Kergon * ref_count is initialised to 1 so pending_complete() 1215b4b610f6SAlasdair G Kergon * won't destroy the primary_pe while we're inside this loop. 12161da177e4SLinus Torvalds */ 12171da177e4SLinus Torvalds e = lookup_exception(&snap->complete, chunk); 121876df1c65SAlasdair G Kergon if (e) 121976df1c65SAlasdair G Kergon goto next_snapshot; 122076df1c65SAlasdair G Kergon 12212913808eSMikulas Patocka pe = __lookup_pending_exception(snap, chunk); 12222913808eSMikulas Patocka if (!pe) { 1223c6621392SMikulas Patocka up_write(&snap->lock); 1224c6621392SMikulas Patocka pe = alloc_pending_exception(snap); 1225c6621392SMikulas Patocka down_write(&snap->lock); 1226c6621392SMikulas Patocka 1227c6621392SMikulas Patocka if (!snap->valid) { 1228c6621392SMikulas Patocka free_pending_exception(pe); 1229c6621392SMikulas Patocka goto next_snapshot; 1230c6621392SMikulas Patocka } 1231c6621392SMikulas Patocka 123235bf659bSMikulas Patocka e = lookup_exception(&snap->complete, chunk); 123335bf659bSMikulas Patocka if (e) { 123435bf659bSMikulas Patocka free_pending_exception(pe); 123535bf659bSMikulas Patocka goto next_snapshot; 123635bf659bSMikulas Patocka } 123735bf659bSMikulas Patocka 1238c6621392SMikulas Patocka pe = __find_pending_exception(snap, pe, chunk); 12391da177e4SLinus Torvalds if (!pe) { 1240695368acSAlasdair G Kergon __invalidate_snapshot(snap, -ENOMEM); 124176df1c65SAlasdair G Kergon goto next_snapshot; 124276df1c65SAlasdair G Kergon } 12432913808eSMikulas Patocka } 12441da177e4SLinus Torvalds 1245b4b610f6SAlasdair G Kergon if (!primary_pe) { 1246b4b610f6SAlasdair G Kergon /* 1247b4b610f6SAlasdair G Kergon * Either every pe here has same 1248b4b610f6SAlasdair G Kergon * primary_pe or none has one yet. 1249b4b610f6SAlasdair G Kergon */ 1250b4b610f6SAlasdair G Kergon if (pe->primary_pe) 1251b4b610f6SAlasdair G Kergon primary_pe = pe->primary_pe; 1252b4b610f6SAlasdair G Kergon else { 1253b4b610f6SAlasdair G Kergon primary_pe = pe; 1254b4b610f6SAlasdair G Kergon first = 1; 1255eccf0817SAlasdair G Kergon } 1256b4b610f6SAlasdair G Kergon 125776df1c65SAlasdair G Kergon bio_list_add(&primary_pe->origin_bios, bio); 125876df1c65SAlasdair G Kergon 1259d2a7ad29SKiyoshi Ueda r = DM_MAPIO_SUBMITTED; 1260b4b610f6SAlasdair G Kergon } 126176df1c65SAlasdair G Kergon 1262b4b610f6SAlasdair G Kergon if (!pe->primary_pe) { 1263b4b610f6SAlasdair G Kergon pe->primary_pe = primary_pe; 12644b832e8dSAlasdair G Kergon get_pending_exception(primary_pe); 1265b4b610f6SAlasdair G Kergon } 126676df1c65SAlasdair G Kergon 1267eccf0817SAlasdair G Kergon if (!pe->started) { 1268eccf0817SAlasdair G Kergon pe->started = 1; 1269eccf0817SAlasdair G Kergon list_add_tail(&pe->list, &pe_queue); 1270eccf0817SAlasdair G Kergon } 12711da177e4SLinus Torvalds 127276df1c65SAlasdair G Kergon next_snapshot: 12731da177e4SLinus Torvalds up_write(&snap->lock); 12741da177e4SLinus Torvalds } 12751da177e4SLinus Torvalds 1276b4b610f6SAlasdair G Kergon if (!primary_pe) 12774b832e8dSAlasdair G Kergon return r; 1278b4b610f6SAlasdair G Kergon 1279b4b610f6SAlasdair G Kergon /* 1280b4b610f6SAlasdair G Kergon * If this is the first time we're processing this chunk and 12814b832e8dSAlasdair G Kergon * ref_count is now 1 it means all the pending exceptions 1282b4b610f6SAlasdair G Kergon * got completed while we were in the loop above, so it falls to 1283b4b610f6SAlasdair G Kergon * us here to remove the primary_pe and submit any origin_bios. 1284b4b610f6SAlasdair G Kergon */ 1285b4b610f6SAlasdair G Kergon 12864b832e8dSAlasdair G Kergon if (first && atomic_dec_and_test(&primary_pe->ref_count)) { 1287b4b610f6SAlasdair G Kergon flush_bios(bio_list_get(&primary_pe->origin_bios)); 1288b4b610f6SAlasdair G Kergon free_pending_exception(primary_pe); 1289b4b610f6SAlasdair G Kergon /* If we got here, pe_queue is necessarily empty. */ 12904b832e8dSAlasdair G Kergon return r; 1291b4b610f6SAlasdair G Kergon } 1292b4b610f6SAlasdair G Kergon 12931da177e4SLinus Torvalds /* 12941da177e4SLinus Torvalds * Now that we have a complete pe list we can start the copying. 12951da177e4SLinus Torvalds */ 1296eccf0817SAlasdair G Kergon list_for_each_entry_safe(pe, next_pe, &pe_queue, list) 12971da177e4SLinus Torvalds start_copy(pe); 12981da177e4SLinus Torvalds 12991da177e4SLinus Torvalds return r; 13001da177e4SLinus Torvalds } 13011da177e4SLinus Torvalds 13021da177e4SLinus Torvalds /* 13031da177e4SLinus Torvalds * Called on a write from the origin driver. 13041da177e4SLinus Torvalds */ 13051da177e4SLinus Torvalds static int do_origin(struct dm_dev *origin, struct bio *bio) 13061da177e4SLinus Torvalds { 13071da177e4SLinus Torvalds struct origin *o; 1308d2a7ad29SKiyoshi Ueda int r = DM_MAPIO_REMAPPED; 13091da177e4SLinus Torvalds 13101da177e4SLinus Torvalds down_read(&_origins_lock); 13111da177e4SLinus Torvalds o = __lookup_origin(origin->bdev); 13121da177e4SLinus Torvalds if (o) 13131da177e4SLinus Torvalds r = __origin_write(&o->snapshots, bio); 13141da177e4SLinus Torvalds up_read(&_origins_lock); 13151da177e4SLinus Torvalds 13161da177e4SLinus Torvalds return r; 13171da177e4SLinus Torvalds } 13181da177e4SLinus Torvalds 13191da177e4SLinus Torvalds /* 13201da177e4SLinus Torvalds * Origin: maps a linear range of a device, with hooks for snapshotting. 13211da177e4SLinus Torvalds */ 13221da177e4SLinus Torvalds 13231da177e4SLinus Torvalds /* 13241da177e4SLinus Torvalds * Construct an origin mapping: <dev_path> 13251da177e4SLinus Torvalds * The context for an origin is merely a 'struct dm_dev *' 13261da177e4SLinus Torvalds * pointing to the real device. 13271da177e4SLinus Torvalds */ 13281da177e4SLinus Torvalds static int origin_ctr(struct dm_target *ti, unsigned int argc, char **argv) 13291da177e4SLinus Torvalds { 13301da177e4SLinus Torvalds int r; 13311da177e4SLinus Torvalds struct dm_dev *dev; 13321da177e4SLinus Torvalds 13331da177e4SLinus Torvalds if (argc != 1) { 133472d94861SAlasdair G Kergon ti->error = "origin: incorrect number of arguments"; 13351da177e4SLinus Torvalds return -EINVAL; 13361da177e4SLinus Torvalds } 13371da177e4SLinus Torvalds 13381da177e4SLinus Torvalds r = dm_get_device(ti, argv[0], 0, ti->len, 13391da177e4SLinus Torvalds dm_table_get_mode(ti->table), &dev); 13401da177e4SLinus Torvalds if (r) { 13411da177e4SLinus Torvalds ti->error = "Cannot get target device"; 13421da177e4SLinus Torvalds return r; 13431da177e4SLinus Torvalds } 13441da177e4SLinus Torvalds 13451da177e4SLinus Torvalds ti->private = dev; 13461da177e4SLinus Torvalds return 0; 13471da177e4SLinus Torvalds } 13481da177e4SLinus Torvalds 13491da177e4SLinus Torvalds static void origin_dtr(struct dm_target *ti) 13501da177e4SLinus Torvalds { 1351028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 13521da177e4SLinus Torvalds dm_put_device(ti, dev); 13531da177e4SLinus Torvalds } 13541da177e4SLinus Torvalds 13551da177e4SLinus Torvalds static int origin_map(struct dm_target *ti, struct bio *bio, 13561da177e4SLinus Torvalds union map_info *map_context) 13571da177e4SLinus Torvalds { 1358028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 13591da177e4SLinus Torvalds bio->bi_bdev = dev->bdev; 13601da177e4SLinus Torvalds 13611da177e4SLinus Torvalds /* Only tell snapshots if this is a write */ 1362d2a7ad29SKiyoshi Ueda return (bio_rw(bio) == WRITE) ? do_origin(dev, bio) : DM_MAPIO_REMAPPED; 13631da177e4SLinus Torvalds } 13641da177e4SLinus Torvalds 13651da177e4SLinus Torvalds #define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r)) 13661da177e4SLinus Torvalds 13671da177e4SLinus Torvalds /* 13681da177e4SLinus Torvalds * Set the target "split_io" field to the minimum of all the snapshots' 13691da177e4SLinus Torvalds * chunk sizes. 13701da177e4SLinus Torvalds */ 13711da177e4SLinus Torvalds static void origin_resume(struct dm_target *ti) 13721da177e4SLinus Torvalds { 1373028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 13741da177e4SLinus Torvalds struct dm_snapshot *snap; 13751da177e4SLinus Torvalds struct origin *o; 13761da177e4SLinus Torvalds chunk_t chunk_size = 0; 13771da177e4SLinus Torvalds 13781da177e4SLinus Torvalds down_read(&_origins_lock); 13791da177e4SLinus Torvalds o = __lookup_origin(dev->bdev); 13801da177e4SLinus Torvalds if (o) 13811da177e4SLinus Torvalds list_for_each_entry (snap, &o->snapshots, list) 1382d0216849SJonathan Brassow chunk_size = min_not_zero(chunk_size, 1383d0216849SJonathan Brassow snap->store->chunk_size); 13841da177e4SLinus Torvalds up_read(&_origins_lock); 13851da177e4SLinus Torvalds 13861da177e4SLinus Torvalds ti->split_io = chunk_size; 13871da177e4SLinus Torvalds } 13881da177e4SLinus Torvalds 13891da177e4SLinus Torvalds static int origin_status(struct dm_target *ti, status_type_t type, char *result, 13901da177e4SLinus Torvalds unsigned int maxlen) 13911da177e4SLinus Torvalds { 1392028867acSAlasdair G Kergon struct dm_dev *dev = ti->private; 13931da177e4SLinus Torvalds 13941da177e4SLinus Torvalds switch (type) { 13951da177e4SLinus Torvalds case STATUSTYPE_INFO: 13961da177e4SLinus Torvalds result[0] = '\0'; 13971da177e4SLinus Torvalds break; 13981da177e4SLinus Torvalds 13991da177e4SLinus Torvalds case STATUSTYPE_TABLE: 14001da177e4SLinus Torvalds snprintf(result, maxlen, "%s", dev->name); 14011da177e4SLinus Torvalds break; 14021da177e4SLinus Torvalds } 14031da177e4SLinus Torvalds 14041da177e4SLinus Torvalds return 0; 14051da177e4SLinus Torvalds } 14061da177e4SLinus Torvalds 14071da177e4SLinus Torvalds static struct target_type origin_target = { 14081da177e4SLinus Torvalds .name = "snapshot-origin", 1409d74f81f8SMilan Broz .version = {1, 6, 0}, 14101da177e4SLinus Torvalds .module = THIS_MODULE, 14111da177e4SLinus Torvalds .ctr = origin_ctr, 14121da177e4SLinus Torvalds .dtr = origin_dtr, 14131da177e4SLinus Torvalds .map = origin_map, 14141da177e4SLinus Torvalds .resume = origin_resume, 14151da177e4SLinus Torvalds .status = origin_status, 14161da177e4SLinus Torvalds }; 14171da177e4SLinus Torvalds 14181da177e4SLinus Torvalds static struct target_type snapshot_target = { 14191da177e4SLinus Torvalds .name = "snapshot", 1420d74f81f8SMilan Broz .version = {1, 6, 0}, 14211da177e4SLinus Torvalds .module = THIS_MODULE, 14221da177e4SLinus Torvalds .ctr = snapshot_ctr, 14231da177e4SLinus Torvalds .dtr = snapshot_dtr, 14241da177e4SLinus Torvalds .map = snapshot_map, 1425cd45daffSMikulas Patocka .end_io = snapshot_end_io, 14261da177e4SLinus Torvalds .resume = snapshot_resume, 14271da177e4SLinus Torvalds .status = snapshot_status, 14281da177e4SLinus Torvalds }; 14291da177e4SLinus Torvalds 14301da177e4SLinus Torvalds static int __init dm_snapshot_init(void) 14311da177e4SLinus Torvalds { 14321da177e4SLinus Torvalds int r; 14331da177e4SLinus Torvalds 14344db6bfe0SAlasdair G Kergon r = dm_exception_store_init(); 14354db6bfe0SAlasdair G Kergon if (r) { 14364db6bfe0SAlasdair G Kergon DMERR("Failed to initialize exception stores"); 14374db6bfe0SAlasdair G Kergon return r; 14384db6bfe0SAlasdair G Kergon } 14394db6bfe0SAlasdair G Kergon 14401da177e4SLinus Torvalds r = dm_register_target(&snapshot_target); 14411da177e4SLinus Torvalds if (r) { 14421da177e4SLinus Torvalds DMERR("snapshot target register failed %d", r); 14431da177e4SLinus Torvalds return r; 14441da177e4SLinus Torvalds } 14451da177e4SLinus Torvalds 14461da177e4SLinus Torvalds r = dm_register_target(&origin_target); 14471da177e4SLinus Torvalds if (r < 0) { 144872d94861SAlasdair G Kergon DMERR("Origin target register failed %d", r); 14491da177e4SLinus Torvalds goto bad1; 14501da177e4SLinus Torvalds } 14511da177e4SLinus Torvalds 14521da177e4SLinus Torvalds r = init_origin_hash(); 14531da177e4SLinus Torvalds if (r) { 14541da177e4SLinus Torvalds DMERR("init_origin_hash failed."); 14551da177e4SLinus Torvalds goto bad2; 14561da177e4SLinus Torvalds } 14571da177e4SLinus Torvalds 1458028867acSAlasdair G Kergon exception_cache = KMEM_CACHE(dm_snap_exception, 0); 14591da177e4SLinus Torvalds if (!exception_cache) { 14601da177e4SLinus Torvalds DMERR("Couldn't create exception cache."); 14611da177e4SLinus Torvalds r = -ENOMEM; 14621da177e4SLinus Torvalds goto bad3; 14631da177e4SLinus Torvalds } 14641da177e4SLinus Torvalds 1465028867acSAlasdair G Kergon pending_cache = KMEM_CACHE(dm_snap_pending_exception, 0); 14661da177e4SLinus Torvalds if (!pending_cache) { 14671da177e4SLinus Torvalds DMERR("Couldn't create pending cache."); 14681da177e4SLinus Torvalds r = -ENOMEM; 14691da177e4SLinus Torvalds goto bad4; 14701da177e4SLinus Torvalds } 14711da177e4SLinus Torvalds 1472cd45daffSMikulas Patocka tracked_chunk_cache = KMEM_CACHE(dm_snap_tracked_chunk, 0); 1473cd45daffSMikulas Patocka if (!tracked_chunk_cache) { 1474cd45daffSMikulas Patocka DMERR("Couldn't create cache to track chunks in use."); 1475cd45daffSMikulas Patocka r = -ENOMEM; 1476cd45daffSMikulas Patocka goto bad5; 1477cd45daffSMikulas Patocka } 1478cd45daffSMikulas Patocka 1479ca3a931fSAlasdair G Kergon ksnapd = create_singlethread_workqueue("ksnapd"); 1480ca3a931fSAlasdair G Kergon if (!ksnapd) { 1481ca3a931fSAlasdair G Kergon DMERR("Failed to create ksnapd workqueue."); 1482ca3a931fSAlasdair G Kergon r = -ENOMEM; 148392e86812SMikulas Patocka goto bad_pending_pool; 1484ca3a931fSAlasdair G Kergon } 1485ca3a931fSAlasdair G Kergon 14861da177e4SLinus Torvalds return 0; 14871da177e4SLinus Torvalds 1488cd45daffSMikulas Patocka bad_pending_pool: 1489cd45daffSMikulas Patocka kmem_cache_destroy(tracked_chunk_cache); 14901da177e4SLinus Torvalds bad5: 14911da177e4SLinus Torvalds kmem_cache_destroy(pending_cache); 14921da177e4SLinus Torvalds bad4: 14931da177e4SLinus Torvalds kmem_cache_destroy(exception_cache); 14941da177e4SLinus Torvalds bad3: 14951da177e4SLinus Torvalds exit_origin_hash(); 14961da177e4SLinus Torvalds bad2: 14971da177e4SLinus Torvalds dm_unregister_target(&origin_target); 14981da177e4SLinus Torvalds bad1: 14991da177e4SLinus Torvalds dm_unregister_target(&snapshot_target); 15001da177e4SLinus Torvalds return r; 15011da177e4SLinus Torvalds } 15021da177e4SLinus Torvalds 15031da177e4SLinus Torvalds static void __exit dm_snapshot_exit(void) 15041da177e4SLinus Torvalds { 1505ca3a931fSAlasdair G Kergon destroy_workqueue(ksnapd); 1506ca3a931fSAlasdair G Kergon 150710d3bd09SMikulas Patocka dm_unregister_target(&snapshot_target); 150810d3bd09SMikulas Patocka dm_unregister_target(&origin_target); 15091da177e4SLinus Torvalds 15101da177e4SLinus Torvalds exit_origin_hash(); 15111da177e4SLinus Torvalds kmem_cache_destroy(pending_cache); 15121da177e4SLinus Torvalds kmem_cache_destroy(exception_cache); 1513cd45daffSMikulas Patocka kmem_cache_destroy(tracked_chunk_cache); 15144db6bfe0SAlasdair G Kergon 15154db6bfe0SAlasdair G Kergon dm_exception_store_exit(); 15161da177e4SLinus Torvalds } 15171da177e4SLinus Torvalds 15181da177e4SLinus Torvalds /* Module hooks */ 15191da177e4SLinus Torvalds module_init(dm_snapshot_init); 15201da177e4SLinus Torvalds module_exit(dm_snapshot_exit); 15211da177e4SLinus Torvalds 15221da177e4SLinus Torvalds MODULE_DESCRIPTION(DM_NAME " snapshot target"); 15231da177e4SLinus Torvalds MODULE_AUTHOR("Joe Thornber"); 15241da177e4SLinus Torvalds MODULE_LICENSE("GPL"); 1525