'Return information about the current state of all volumes.
:return: Result indicating success.'

@app.route('/VolumeDriver.List', methods=['POST'])
@_endpoint(u'List')
def volumedriver_list(self):

    listing = DeferredContext(self._flocker_client.list_datasets_configuration())
    def got_configured(configured):
        results = []
        for dataset in configured:
            if (NAME_FIELD not in dataset.metadata):
                continue
            dataset_name = dataset.metadata[NAME_FIELD]
            d = self._get_path_from_dataset_id(dataset.dataset_id)
            d.addCallback((lambda path, name=dataset_name: (path, name)))
            results.append(d)
        return gatherResults(results)
    listing.addCallback(got_configured)
    def got_paths(results):
        return {u'Err': u'', u'Volumes': sorted([{u'Name': name, u'Mountpoint': (u'' if (path is None) else path.path)} for (path, name) in results])}
    listing.addCallback(got_paths)
    return listing.result
