Now that op blockers are in use, we can ensure that no other sources are
generating I/O on a BlockDriverState. Therefore it is possible to drain
requests for a single BDS.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 1413889440-32577-7-git-send-email-stefanha@redhat.com