fix(extensions/lvm): resolve label mount point via findmnt, use case

Replace the `mount | grep | awk '{print $3}'` mount-point lookup with a
single findmnt call — robust to spaces in paths and to multiple mounts of
the same device — and convert the label dispatch and the unsupported-fs
guard from if/elif chains to case blocks.

Also label ext2 roots via e2label (previously only ext4 was matched, so
ext2 fell through to the skip branch), and drop the stray escaped quotes
in the xfs label command, which were otherwise embedded verbatim into the
filesystem label.

Assisted-by: Claude:claude-opus-4.8

Author: iav

extensions/lvm.sh

@@ -68,38 +68,53 @@ function prepare_root_device__create_volume_group() {
 }
 
 function label_partition() {
-	if [ "$ROOTFS_TYPE" == "ext4" ]; then
-		e2label "/dev/mapper/${LVM_VG_NAME}-root" "${ROOT_FS_LABEL}"
-	elif [ "$ROOTFS_TYPE" == "btrfs" ]; then
-		btrfs filesystem label "$(mount | grep "/dev/mapper/${LVM_VG_NAME}-root" | awk '{print $3}')" "${ROOT_FS_LABEL}"
-	elif [ "$ROOTFS_TYPE" == "nilfs2" ]; then
-		nilfs-tune -L "${ROOT_FS_LABEL}" "/dev/mapper/${LVM_VG_NAME}-root"
-	elif [ "$ROOTFS_TYPE" == "xfs" ]; then
-		xfs_io -c "label -s \"${ROOT_FS_LABEL}\"" "$(mount | grep "/dev/mapper/${LVM_VG_NAME}-root" | awk '{print $3}')"
-	fi
+	local rootdevice="/dev/mapper/${LVM_VG_NAME}-root"
+	# btrfs and xfs relabel via the mount point; resolve it structurally
+	# (findmnt is a single util-linux call, robust to spaces and to multiple
+	# mounts of the same device) instead of parsing mount(8) output.
+	local mountpoint
+	mountpoint="$(findmnt --noheadings --first-only --output TARGET --source "${rootdevice}")"
+
+	case "${ROOTFS_TYPE}" in
+		ext4 | ext2)
+			e2label "${rootdevice}" "${ROOT_FS_LABEL}"
+			;;
+		btrfs)
+			btrfs filesystem label "${mountpoint}" "${ROOT_FS_LABEL}"
+			;;
+		nilfs2)
+			nilfs-tune -L "${ROOT_FS_LABEL}" "${rootdevice}"
+			;;
+		xfs)
+			xfs_io -c "label -s ${ROOT_FS_LABEL}" "${mountpoint}"
+			;;
+	esac
 }
 
 function format_partitions__format_lvm() {
-	# Skip unknown filesystems
-	if echo "ext4 btrfs nilfs2 xfs" | grep -v -w -q "$ROOTFS_TYPE"; then
-		display_alert "LVM partition labels skipped" "${EXTENSION}" "info"
-		return
-	fi
+	# Only these filesystems support relabeling the mounted root here; skip the rest.
+	case "${ROOTFS_TYPE}" in
+		ext4 | ext2 | btrfs | nilfs2 | xfs) ;;
+		*)
+			display_alert "LVM partition labels skipped" "${EXTENSION} - unsupported ${ROOTFS_TYPE}" "info"
+			return
+			;;
+	esac
 
 	# Label the root volume
 	if label_partition; then
 		blkid | grep "${LVM_VG_NAME}" >> "${DEST}/${LOG_SUBPATH}/lvm.log" 2>&1
-		display_alert "LVM labeled $ROOTFS_TYPE partitions" "${EXTENSION}" "info"
+		display_alert "LVM labeled ${ROOTFS_TYPE} partitions" "${EXTENSION}" "info"
 	else
-		display_alert "LVM failed to label $ROOTFS_TYPE partition. Ignoring." "${EXTENSION}" "info"
+		display_alert "LVM failed to label ${ROOTFS_TYPE} partition. Ignoring." "${EXTENSION}" "info"
 	fi
 }
 
-function post_umount_final_image__cleanup_lvm(){
+function post_umount_final_image__cleanup_lvm() {
 	execute_and_remove_cleanup_handler cleanup_lvm
 }
 
 function cleanup_lvm() {
 	vgchange -a n "${LVM_VG_NAME}" >> "${DEST}/${LOG_SUBPATH}/lvm.log" 2>&1 || true
 	display_alert "LVM deactivated volume group" "${EXTENSION}" "info"
-}
+}