'Makes REST API call to update a volume information.
:param name: name of the volume to be updated
:param vpool: name of vpool
:returns: Created task details in JSON response payload'

def update(self, prefix_path, name, vpool):

    namelist = []
    if isinstance(name, list):
        namelist = name
    else:
        namelist.append(name)
    volumeurilist = []
    for item in namelist:
        volume_uri = self.volume_query(prefix_path, item)
        volumeurilist.append(volume_uri)
    vpool_obj = virtualpool.VirtualPool(self.ipaddr, self.port)
    vpool_uri = vpool_obj.vpool_query(vpool, 'block')
    params = {'vpool': vpool_uri, 'volumes': volumeurilist}
    body = oslo_serialization.jsonutils.dumps(params)
    (s, h) = common.service_json_request(self.ipaddr, self.port, 'POST', Volume.URI_VOLUME_CHANGE_VPOOL, body)
    o = common.json_decode(s)
    return o
