This flag signifies that a write request will not change the visible
disk content.  With this flag set, it is sufficient to have the
BLK_PERM_WRITE_UNCHANGED permission instead of BLK_PERM_WRITE.
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: NAlberto Garcia <berto@igalia.com>
Message-id: 20180421132929.21610-4-mreitz@redhat.com
Reviewed-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NMax Reitz <mreitz@redhat.com>