blkid: add type display for btrfs

Signed-off-by: Sven-Göran Bergh <svengbergh-busybox@yahoo.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/util-linux/volume_id/btrfs.c b/util-linux/volume_id/btrfs.c
index 777b809..ee71d2e 100644
--- a/util-linux/volume_id/btrfs.c
+++ b/util-linux/volume_id/btrfs.c
@@ -102,6 +102,7 @@
 	// N.B.: btrfs natively supports 256 (>VOLUME_ID_LABEL_SIZE) size labels
 	volume_id_set_label_string(id, sb->label, VOLUME_ID_LABEL_SIZE);
 	volume_id_set_uuid(id, sb->fsid, UUID_DCE);
+	IF_FEATURE_BLKID_TYPE(id->type = "btrfs";)
 
 	return 0;
 }