'Extend volume.'

def extend_volume(self, volume, new_size):

    LOG.debug('enter:    extend_volume:    volume    %s.', volume['name'])
    vdisk_name = volume['name']
    self._wait_vdisk_copy_completed(vdisk_name)
    extend_amt = (int(new_size) - volume['size'])
    ssh_cmd = ['svctask', 'expandvdisksize', '-size', six.text_type(extend_amt), '-unit', 'gb', vdisk_name]
    (out, err) = self._ssh(ssh_cmd)
    self._assert_ssh_return((not out.strip()), 'extend_volume', ssh_cmd, out, err)
    LOG.debug('leave:    extend_volume:    volume    %s.', volume['name'])
