'Extend an existing volume.'

def extend_volume(self, volume, new_size):

    name = (self.configuration.zadara_vol_name_template % volume['name'])
    (vpsa_vol, size) = self._get_vpsa_volume_name_and_size(name)
    if (not vpsa_vol):
        msg = (_('Volume    %(name)s    could    not    be    found.    It    might    be    already    deleted') % {'name': name})
        LOG.error(msg)
        raise exception.ZadaraVolumeNotFound(reason=msg)
    if (new_size < size):
        raise exception.InvalidInput(reason=(_('%(new_size)s    <    current    size    %(size)s') % {'new_size': new_size, 'size': size}))
    expand_size = (new_size - size)
    self.vpsa.send_cmd('expand_volume', vpsa_vol=vpsa_vol, size=expand_size)
