'Extend an existing volume.'

def extend_volume(self, volume, new_size):

    old_size = volume.size
    try:
        size = (int(new_size) * units.Gi)
        self._resize(volume, size=size)
    except Exception:
        msg = (_('Failed    to    Extend    Volume    %(volname)s') % {'volname': volume.name})
        LOG.error(msg)
        raise exception.VolumeBackendAPIException(data=msg)
    LOG.debug('Extend    volume    from    %(old_size)s    GB    to    %(new_size)s    GB.', {'old_size': old_size, 'new_size': new_size})
