code: func listMeta(tx *bolt.Tx) []volumeMetadata {
  	var ls []volumeMetadata
  	b := tx.Bucket(volumeBucketName)
  	b.ForEach(func(k, v []byte) error {
  		if len(v) == 0 {
  			// don't try to unmarshal an empty value
  			return nil
  		}
  
  		var m volumeMetadata
  		if err := json.Unmarshal(v, &m); err != nil {
  			// Just log the error
  			logrus.Errorf("Error while reading volume metadata for volume %q: %v", string(k), err)
  			return nil
  		}
  		ls = append(ls, m)
  		return nil
  	})
  	return ls
  }
docs: // listMeta is used during restore to get the list of volume metadata
  // from the on-disk database.
  // Any errors that occur are only logged.