Commit aa14edeb994f8f7e223d02ad14780bf2fa719f6d
Committed by
Linus Torvalds
Linus Torvalds
1 parent
cb82a6cdf9
Exists in
master
and in
4 other branches
[PATCH] device-mapper snapshot: load metadata on creation
Move snapshot metadata loading to happen when the table is created instead of when the device is resumed. Writes to the origin device don't trigger exceptions until each snapshot table becomes active when resume() is called on each snapshot. If you're using lvm2, for this patch to work properly you should update to lvm2 version 2.02.01 or later and device-mapper version 1.02.02 or later. Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Showing 2 changed files with 15 additions and 12 deletions Side-by-side Diff
drivers/md/dm-snap.c
| ... | ... | @@ -373,16 +373,11 @@ |
| 373 | 373 | |
| 374 | 374 | static void read_snapshot_metadata(struct dm_snapshot *s) |
| 375 | 375 | { |
| 376 | - if (s->have_metadata) | |
| 377 | - return; | |
| 378 | - | |
| 379 | 376 | if (s->store.read_metadata(&s->store)) { |
| 380 | 377 | down_write(&s->lock); |
| 381 | 378 | s->valid = 0; |
| 382 | 379 | up_write(&s->lock); |
| 383 | 380 | } |
| 384 | - | |
| 385 | - s->have_metadata = 1; | |
| 386 | 381 | } |
| 387 | 382 | |
| 388 | 383 | /* |
| ... | ... | @@ -471,7 +466,7 @@ |
| 471 | 466 | s->chunk_shift = ffs(chunk_size) - 1; |
| 472 | 467 | |
| 473 | 468 | s->valid = 1; |
| 474 | - s->have_metadata = 0; | |
| 469 | + s->active = 0; | |
| 475 | 470 | s->last_percent = 0; |
| 476 | 471 | init_rwsem(&s->lock); |
| 477 | 472 | s->table = ti->table; |
| 478 | 473 | |
| ... | ... | @@ -506,7 +501,11 @@ |
| 506 | 501 | goto bad5; |
| 507 | 502 | } |
| 508 | 503 | |
| 504 | + /* Metadata must only be loaded into one table at once */ | |
| 505 | + read_snapshot_metadata(s); | |
| 506 | + | |
| 509 | 507 | /* Add snapshot to the list of snapshots for this origin */ |
| 508 | + /* Exceptions aren't triggered till snapshot_resume() is called */ | |
| 510 | 509 | if (register_snapshot(s)) { |
| 511 | 510 | r = -EINVAL; |
| 512 | 511 | ti->error = "Cannot register snapshot origin"; |
| ... | ... | @@ -862,7 +861,9 @@ |
| 862 | 861 | { |
| 863 | 862 | struct dm_snapshot *s = (struct dm_snapshot *) ti->private; |
| 864 | 863 | |
| 865 | - read_snapshot_metadata(s); | |
| 864 | + down_write(&s->lock); | |
| 865 | + s->active = 1; | |
| 866 | + up_write(&s->lock); | |
| 866 | 867 | } |
| 867 | 868 | |
| 868 | 869 | static int snapshot_status(struct dm_target *ti, status_type_t type, |
| ... | ... | @@ -932,8 +933,8 @@ |
| 932 | 933 | /* Do all the snapshots on this origin */ |
| 933 | 934 | list_for_each_entry (snap, snapshots, list) { |
| 934 | 935 | |
| 935 | - /* Only deal with valid snapshots */ | |
| 936 | - if (!snap->valid) | |
| 936 | + /* Only deal with valid and active snapshots */ | |
| 937 | + if (!snap->valid || !snap->active) | |
| 937 | 938 | continue; |
| 938 | 939 | |
| 939 | 940 | /* Nothing to do if writing beyond end of snapshot */ |
| ... | ... | @@ -1104,7 +1105,7 @@ |
| 1104 | 1105 | |
| 1105 | 1106 | static struct target_type origin_target = { |
| 1106 | 1107 | .name = "snapshot-origin", |
| 1107 | - .version = {1, 0, 1}, | |
| 1108 | + .version = {1, 1, 0}, | |
| 1108 | 1109 | .module = THIS_MODULE, |
| 1109 | 1110 | .ctr = origin_ctr, |
| 1110 | 1111 | .dtr = origin_dtr, |
| ... | ... | @@ -1115,7 +1116,7 @@ |
| 1115 | 1116 | |
| 1116 | 1117 | static struct target_type snapshot_target = { |
| 1117 | 1118 | .name = "snapshot", |
| 1118 | - .version = {1, 0, 1}, | |
| 1119 | + .version = {1, 1, 0}, | |
| 1119 | 1120 | .module = THIS_MODULE, |
| 1120 | 1121 | .ctr = snapshot_ctr, |
| 1121 | 1122 | .dtr = snapshot_dtr, |
drivers/md/dm-snap.h
| ... | ... | @@ -99,7 +99,9 @@ |
| 99 | 99 | |
| 100 | 100 | /* You can't use a snapshot if this is 0 (e.g. if full) */ |
| 101 | 101 | int valid; |
| 102 | - int have_metadata; | |
| 102 | + | |
| 103 | + /* Origin writes don't trigger exceptions until this is set */ | |
| 104 | + int active; | |
| 103 | 105 | |
| 104 | 106 | /* Used for display of table */ |
| 105 | 107 | char type; |