'Extend an existing volume.
:param volume: volume reference
:param new_size: volume new size in GB'

def extend_volume(self, volume, new_size):

    LOG.info('Extending    volume:    %(id)s    New    size:    %(size)s    GB', {'id': volume['id'], 'size': new_size})
    (pool, group, name) = self._get_volume_path(volume).split('/')
    url = ('storage/pools/%(pool)s/volumeGroups/%(group)s/volumes/%(name)s' % {'pool': pool, 'group': group, 'name': name})
    self.nef.put(url, {'volumeSize': (new_size * units.Gi)})
