// Stat a volume entry.
		if err = Access(volumeDir); err != nil {
			return convertAccessError(err, errVolumeAccessDenied)
		}
	}

	// Use a small block size to start sending quickly
	w := newMetacacheWriter(wr, 16<<10)
	w.reuseBlocks = true // We are not sharing results, so reuse buffers.
	defer w.Close()
	out, err := w.stream()
	if err != nil {
		return err
	}
	defer xioutil.SafeClose(out)