16fde5f2c2
When copying L2 tables (this happens only with internal snapshots), the order wasn't completely safe, so that after a crash you could end up with a L2 table that has too low refcount, possibly leading to corruption in the long run. This patch puts the operations in the right order: First allocate the new L2 table and replace the reference, and only then decrease the refcount of the old table. Signed-off-by: Kevin Wolf <kwolf@redhat.com>