The copy-on-read feature is expressed by adding a new node layer in
qemu when using -blockdev. Since we will keep these per-disk (as opposed
to per storage source) we need to store the appropriate node names in
the disk definition.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>