'Unquiesce an instance on this host.
If snapshots\' image mapping is provided, it waits until snapshots are
completed before unqueiscing.'

@messaging.expected_exceptions(exception.InstanceQuiesceNotSupported, exception.QemuGuestAgentNotEnabled, exception.NovaException, NotImplementedError)
@wrap_exception()
def unquiesce_instance(self, context, instance, mapping=None):

    context = context.elevated()
    if mapping:
        try:
            self._wait_for_snapshots_completion(context, mapping)
        except Exception as error:
            LOG.exception('Exception    while    waiting    completion    of    volume    snapshots:    %s', error, instance=instance)
    image_meta = objects.ImageMeta.from_instance(instance)
    self.driver.unquiesce(context, instance, image_meta)
