From 2c945820cab96ebf265598d998e63ef22393d0d4 Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Mon, 3 Mar 2014 17:19:22 -0500 Subject: [PATCH] dm snapshot: fix metadata corruption Commit 55494bf2947dccdf2 ("dm snapshot: use dm-bufio") broke snapshots. Before that 3.14-rc1 commit, loading a snapshot's list of exceptions involved reading exception areas one by one into ps->area and inserting those exceptions into the hash table. Commit 55494bf2947dccdf2 changed it so that dm-bufio with prefetch is used to load exceptions in batchs. Exceptions are loaded correctly, but ps->area is left uninitialized. When a new exception is allocated, it is stored in this uninitialized ps->area which will be written to the disk. This causes metadata corruption. Fix this corruption by copying the last area that was read via dm-bufio into ps->area. Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer --- drivers/md/dm-snap-persistent.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/md/dm-snap-persistent.c b/drivers/md/dm-snap-persistent.c index afc3d01..d6e8817 100644 --- a/drivers/md/dm-snap-persistent.c +++ b/drivers/md/dm-snap-persistent.c @@ -546,6 +546,9 @@ static int read_exceptions(struct pstore *ps, r = insert_exceptions(ps, area, callback, callback_context, &full); + if (!full) + memcpy(ps->area, area, ps->store->chunk_size << SECTOR_SHIFT); + dm_bufio_release(bp); dm_bufio_forget(client, chunk); -- 2.7.4