btrfs-mksnapshot: detect default subvolume on "/"

diff --git a/btrfs/mksnapshot/btrfs-mksnapshot b/btrfs/mksnapshot/btrfs-mksnapshot
index 59b8c5644efe07da0100114a1a99d56f3680f45a..45289810034e2445f0922acd893cecb851ac24ad 100755 (executable)
--- a/btrfs/mksnapshot/btrfs-mksnapshot
+++ b/btrfs/mksnapshot/btrfs-mksnapshot
@@ -67,6 +67,9 @@ VOLUME_NAME=`grep " btrfs " /etc/fstab \
        | grep "subvol=" \
        | grep " $VOLUME_PATH " \
        | sed -r 's|.*subvol=([[:alnum:]]*).*|\1|'`
+if [ -z "$VOLUME_NAME" -a "$VOLUME_PATH" = "/" ]; then
+       VOLUME_NAME=`btrfs subvolume get-default / | cut -d' ' -f9`
+fi
 if [ -z "$VOLUME_NAME" ]; then
        echo "$NAME: Failed to detect btrfs subvolume name for \"$VOLUME_PATH\"!"
        exit 1