This is in preparation to mark bdrv_set_backing_hd() as
GRAPH_UNLOCKED.
Switch to using the bdrv_set_backing_hd_drained() variant. For the
first pair of calls to avoid draining and locking twice in a row
within the individual calls. For the third call, so that the drained
and locked section can also cover bdrv_cow_bs().
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Message-ID: <20250530151125.955508-27-f.ebner@proxmox.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>