From: Mikulas Patocka <mpatocka@xxxxxxxxxx>
If we are merging an invalidated snapshot, redirect all accesses to the
origin device. This is safe because snapshot_merge_process() will
stop_merge() if the merging snapshot becomes invalid.
Allowing the origin device to remain functional is important because it
may contain the root filesystem.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Reviewed-by: Mike Snitzer <snitzer@xxxxxxxxxx>
---
drivers/md/dm-snap.c | 9 ++++-----
1 files changed, 4 insertions(+), 5 deletions(-)
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index c3578f5..257e2d1 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -1573,11 +1573,9 @@ static int snapshot_merge_map(struct dm_target *ti, struct bio *bio,
down_write(&s->lock);
- /* Full snapshots are not usable */
- if (!s->valid) {
- r = -EIO;
- goto out_unlock;
- }
+ /* Full merging snapshots are redirected to the origin */
+ if (!s->valid)
+ goto redirect_to_origin;
/* If the block is already remapped - use that */
e = dm_lookup_exception(&s->complete, chunk);
@@ -1600,6 +1598,7 @@ static int snapshot_merge_map(struct dm_target *ti, struct bio *bio,
goto out_unlock;
}
+ redirect_to_origin:
bio->bi_bdev = s->origin->bdev;
if (bio_rw(bio) == WRITE) {
--
1.6.5.2
--
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