'Check if instance files located on shared storage.
This runs check on the destination host, and then calls
back to the source host to check the results.
:param context: security context
:param instance: nova.objects.instance.Instance object
:returns:
- tempfile: A dict containing the tempfile info on the destination
host
- None:
1. If the instance path is not existing.
2. If the image backend is shared block storage type.'

def check_instance_shared_storage_local(self, context, instance):

    if self.image_backend.backend().is_shared_block_storage():
        return None
    dirpath = libvirt_utils.get_instance_path(instance)
    if (not os.path.exists(dirpath)):
        return None
    (fd, tmp_file) = tempfile.mkstemp(dir=dirpath)
    LOG.debug('Creating    tmpfile    %s    to    verify    with    other    compute    node    that    the    instance    is    on    the    same    shared    storage.', tmp_file, instance=instance)
    os.close(fd)
    return {'filename': tmp_file}
