This patch is similar to 171e3d6b9997c98a97d0c525867f7cd9b640cadd
which fixed qcow2:
Returning -EIO is far from optimal, but at least it's an error code.
In addition to read/write failures, -EIO is also returned when
decompress_cluster failed.
Cc: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Weil <weil@mail.berlios.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>