blockdev: preserve readonly and snapshot states across media changes If readonly=on is given at device creation time, the ->readonly flag needs to be set in the block driver state for this device so that readonly-ness is preserved across media changes (qmp change command). Similarly, to preserve the snapshot property requires ->open_flags to be correct. Signed-off-by: Kevin Shanahan <kmshanah@disenchant.net> Signed-off-by: Kevin Wolf <kwolf@redhat.com>