'Update backing VM\'s disk UUID.
:param backing: Reference to backing VM
:param disk_uuid: New disk UUID'

def update_backing_disk_uuid(self, backing, disk_uuid):

    LOG.debug('Reconfiguring    backing    VM:    %(backing)s    to    change    disk    UUID    to:    %(disk_uuid)s.', {'backing': backing, 'disk_uuid': disk_uuid})
    disk_device = self._get_disk_device(backing)
    disk_device.backing.uuid = disk_uuid
    cf = self._session.vim.client.factory
    disk_spec = cf.create('ns0:VirtualDeviceConfigSpec')
    disk_spec.device = disk_device
    disk_spec.operation = 'edit'
    reconfig_spec = cf.create('ns0:VirtualMachineConfigSpec')
    reconfig_spec.deviceChange = [disk_spec]
    self._reconfigure_backing(backing, reconfig_spec)
    LOG.debug('Backing    VM:    %(backing)s    reconfigured    with    new    disk    UUID:    %(disk_uuid)s.', {'backing': backing, 'disk_uuid': disk_uuid})
