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Diffstat (limited to 'drivers/md/dm-snap.c')
-rw-r--r--drivers/md/dm-snap.c107
1 files changed, 97 insertions, 10 deletions
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 1ba8a47d61b1..de302702ab3e 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -40,6 +40,11 @@
40 */ 40 */
41#define SNAPSHOT_PAGES (((1UL << 20) >> PAGE_SHIFT) ? : 1) 41#define SNAPSHOT_PAGES (((1UL << 20) >> PAGE_SHIFT) ? : 1)
42 42
43/*
44 * The size of the mempool used to track chunks in use.
45 */
46#define MIN_IOS 256
47
43static struct workqueue_struct *ksnapd; 48static struct workqueue_struct *ksnapd;
44static void flush_queued_bios(struct work_struct *work); 49static void flush_queued_bios(struct work_struct *work);
45 50
@@ -93,6 +98,42 @@ static struct kmem_cache *exception_cache;
93static struct kmem_cache *pending_cache; 98static struct kmem_cache *pending_cache;
94static mempool_t *pending_pool; 99static mempool_t *pending_pool;
95 100
101struct dm_snap_tracked_chunk {
102 struct hlist_node node;
103 chunk_t chunk;
104};
105
106static struct kmem_cache *tracked_chunk_cache;
107
108static struct dm_snap_tracked_chunk *track_chunk(struct dm_snapshot *s,
109 chunk_t chunk)
110{
111 struct dm_snap_tracked_chunk *c = mempool_alloc(s->tracked_chunk_pool,
112 GFP_NOIO);
113 unsigned long flags;
114
115 c->chunk = chunk;
116
117 spin_lock_irqsave(&s->tracked_chunk_lock, flags);
118 hlist_add_head(&c->node,
119 &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)]);
120 spin_unlock_irqrestore(&s->tracked_chunk_lock, flags);
121
122 return c;
123}
124
125static void stop_tracking_chunk(struct dm_snapshot *s,
126 struct dm_snap_tracked_chunk *c)
127{
128 unsigned long flags;
129
130 spin_lock_irqsave(&s->tracked_chunk_lock, flags);
131 hlist_del(&c->node);
132 spin_unlock_irqrestore(&s->tracked_chunk_lock, flags);
133
134 mempool_free(c, s->tracked_chunk_pool);
135}
136
96/* 137/*
97 * One of these per registered origin, held in the snapshot_origins hash 138 * One of these per registered origin, held in the snapshot_origins hash
98 */ 139 */
@@ -482,6 +523,7 @@ static int set_chunk_size(struct dm_snapshot *s, const char *chunk_size_arg,
482static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv) 523static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
483{ 524{
484 struct dm_snapshot *s; 525 struct dm_snapshot *s;
526 int i;
485 int r = -EINVAL; 527 int r = -EINVAL;
486 char persistent; 528 char persistent;
487 char *origin_path; 529 char *origin_path;
@@ -564,11 +606,24 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
564 goto bad5; 606 goto bad5;
565 } 607 }
566 608
609 s->tracked_chunk_pool = mempool_create_slab_pool(MIN_IOS,
610 tracked_chunk_cache);
611 if (!s->tracked_chunk_pool) {
612 ti->error = "Could not allocate tracked_chunk mempool for "
613 "tracking reads";
614 goto bad6;
615 }
616
617 for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++)
618 INIT_HLIST_HEAD(&s->tracked_chunk_hash[i]);
619
620 spin_lock_init(&s->tracked_chunk_lock);
621
567 /* Metadata must only be loaded into one table at once */ 622 /* Metadata must only be loaded into one table at once */
568 r = s->store.read_metadata(&s->store); 623 r = s->store.read_metadata(&s->store);
569 if (r < 0) { 624 if (r < 0) {
570 ti->error = "Failed to read snapshot metadata"; 625 ti->error = "Failed to read snapshot metadata";
571 goto bad6; 626 goto bad_load_and_register;
572 } else if (r > 0) { 627 } else if (r > 0) {
573 s->valid = 0; 628 s->valid = 0;
574 DMWARN("Snapshot is marked invalid."); 629 DMWARN("Snapshot is marked invalid.");
@@ -582,7 +637,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
582 if (register_snapshot(s)) { 637 if (register_snapshot(s)) {
583 r = -EINVAL; 638 r = -EINVAL;
584 ti->error = "Cannot register snapshot origin"; 639 ti->error = "Cannot register snapshot origin";
585 goto bad6; 640 goto bad_load_and_register;
586 } 641 }
587 642
588 ti->private = s; 643 ti->private = s;
@@ -590,6 +645,9 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
590 645
591 return 0; 646 return 0;
592 647
648 bad_load_and_register:
649 mempool_destroy(s->tracked_chunk_pool);
650
593 bad6: 651 bad6:
594 dm_kcopyd_client_destroy(s->kcopyd_client); 652 dm_kcopyd_client_destroy(s->kcopyd_client);
595 653
@@ -624,6 +682,9 @@ static void __free_exceptions(struct dm_snapshot *s)
624 682
625static void snapshot_dtr(struct dm_target *ti) 683static void snapshot_dtr(struct dm_target *ti)
626{ 684{
685#ifdef CONFIG_DM_DEBUG
686 int i;
687#endif
627 struct dm_snapshot *s = ti->private; 688 struct dm_snapshot *s = ti->private;
628 689
629 flush_workqueue(ksnapd); 690 flush_workqueue(ksnapd);
@@ -632,6 +693,13 @@ static void snapshot_dtr(struct dm_target *ti)
632 /* After this returns there can be no new kcopyd jobs. */ 693 /* After this returns there can be no new kcopyd jobs. */
633 unregister_snapshot(s); 694 unregister_snapshot(s);
634 695
696#ifdef CONFIG_DM_DEBUG
697 for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++)
698 BUG_ON(!hlist_empty(&s->tracked_chunk_hash[i]));
699#endif
700
701 mempool_destroy(s->tracked_chunk_pool);
702
635 __free_exceptions(s); 703 __free_exceptions(s);
636 704
637 dm_put_device(ti, s->origin); 705 dm_put_device(ti, s->origin);
@@ -974,14 +1042,10 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio,
974 start_copy(pe); 1042 start_copy(pe);
975 goto out; 1043 goto out;
976 } 1044 }
977 } else 1045 } else {
978 /*
979 * FIXME: this read path scares me because we
980 * always use the origin when we have a pending
981 * exception. However I can't think of a
982 * situation where this is wrong - ejt.
983 */
984 bio->bi_bdev = s->origin->bdev; 1046 bio->bi_bdev = s->origin->bdev;
1047 map_context->ptr = track_chunk(s, chunk);
1048 }
985 1049
986 out_unlock: 1050 out_unlock:
987 up_write(&s->lock); 1051 up_write(&s->lock);
@@ -989,6 +1053,18 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio,
989 return r; 1053 return r;
990} 1054}
991 1055
1056static int snapshot_end_io(struct dm_target *ti, struct bio *bio,
1057 int error, union map_info *map_context)
1058{
1059 struct dm_snapshot *s = ti->private;
1060 struct dm_snap_tracked_chunk *c = map_context->ptr;
1061
1062 if (c)
1063 stop_tracking_chunk(s, c);
1064
1065 return 0;
1066}
1067
992static void snapshot_resume(struct dm_target *ti) 1068static void snapshot_resume(struct dm_target *ti)
993{ 1069{
994 struct dm_snapshot *s = ti->private; 1070 struct dm_snapshot *s = ti->private;
@@ -1266,6 +1342,7 @@ static struct target_type snapshot_target = {
1266 .ctr = snapshot_ctr, 1342 .ctr = snapshot_ctr,
1267 .dtr = snapshot_dtr, 1343 .dtr = snapshot_dtr,
1268 .map = snapshot_map, 1344 .map = snapshot_map,
1345 .end_io = snapshot_end_io,
1269 .resume = snapshot_resume, 1346 .resume = snapshot_resume,
1270 .status = snapshot_status, 1347 .status = snapshot_status,
1271}; 1348};
@@ -1306,11 +1383,18 @@ static int __init dm_snapshot_init(void)
1306 goto bad4; 1383 goto bad4;
1307 } 1384 }
1308 1385
1386 tracked_chunk_cache = KMEM_CACHE(dm_snap_tracked_chunk, 0);
1387 if (!tracked_chunk_cache) {
1388 DMERR("Couldn't create cache to track chunks in use.");
1389 r = -ENOMEM;
1390 goto bad5;
1391 }
1392
1309 pending_pool = mempool_create_slab_pool(128, pending_cache); 1393 pending_pool = mempool_create_slab_pool(128, pending_cache);
1310 if (!pending_pool) { 1394 if (!pending_pool) {
1311 DMERR("Couldn't create pending pool."); 1395 DMERR("Couldn't create pending pool.");
1312 r = -ENOMEM; 1396 r = -ENOMEM;
1313 goto bad5; 1397 goto bad_pending_pool;
1314 } 1398 }
1315 1399
1316 ksnapd = create_singlethread_workqueue("ksnapd"); 1400 ksnapd = create_singlethread_workqueue("ksnapd");
@@ -1324,6 +1408,8 @@ static int __init dm_snapshot_init(void)
1324 1408
1325 bad6: 1409 bad6:
1326 mempool_destroy(pending_pool); 1410 mempool_destroy(pending_pool);
1411 bad_pending_pool:
1412 kmem_cache_destroy(tracked_chunk_cache);
1327 bad5: 1413 bad5:
1328 kmem_cache_destroy(pending_cache); 1414 kmem_cache_destroy(pending_cache);
1329 bad4: 1415 bad4:
@@ -1355,6 +1441,7 @@ static void __exit dm_snapshot_exit(void)
1355 mempool_destroy(pending_pool); 1441 mempool_destroy(pending_pool);
1356 kmem_cache_destroy(pending_cache); 1442 kmem_cache_destroy(pending_cache);
1357 kmem_cache_destroy(exception_cache); 1443 kmem_cache_destroy(exception_cache);
1444 kmem_cache_destroy(tracked_chunk_cache);
1358} 1445}
1359 1446
1360/* Module hooks */ 1447/* Module hooks */