build: label kernel and rootfs ext4 volumes

UUID of ext4 volumes generated by make_ext4fs are determined by volume
label and it will all be 57f8f4bc-abf4-655f-bf67-946fc0f9f25b when label
is empty

Labeling them does not make them unique but tools like block command
from fstools have a better chance differentiating them

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>

include/image.mk

@@ -287,7 +287,7 @@ define Image/mkfs/ubifs
 endef
 
 define Image/mkfs/ext4
-	$(STAGING_DIR_HOST)/bin/make_ext4fs \
+	$(STAGING_DIR_HOST)/bin/make_ext4fs -L rootfs \
 		-l $(ROOTFS_PARTSIZE) -b $(CONFIG_TARGET_EXT4_BLOCKSIZE) \
 		$(if $(CONFIG_TARGET_EXT4_RESERVED_PCT),-m $(CONFIG_TARGET_EXT4_RESERVED_PCT)) \
 		$(if $(CONFIG_TARGET_EXT4_JOURNAL),,-J) \

scripts/gen_image_generic.sh

@@ -30,6 +30,6 @@ ROOTFSSIZE="$(($4 / 512))"
 [ -n "$PADDING" ] && dd if=/dev/zero of="$OUTPUT" bs=512 seek="$ROOTFSOFFSET" conv=notrunc count="$ROOTFSSIZE"
 dd if="$ROOTFSIMAGE" of="$OUTPUT" bs=512 seek="$ROOTFSOFFSET" conv=notrunc
 
-make_ext4fs -J -l "$KERNELSIZE" "$OUTPUT.kernel" "$KERNELDIR"
+make_ext4fs -J -L kernel -l "$KERNELSIZE" "$OUTPUT.kernel" "$KERNELDIR"
 dd if="$OUTPUT.kernel" of="$OUTPUT" bs=512 seek="$KERNELOFFSET" conv=notrunc
 rm -f "$OUTPUT.kernel"

target/linux/mvebu/image/Makefile

@@ -38,7 +38,7 @@ define Build/boot-img-ext4
 	$(foreach dts,$(DEVICE_DTS), $(CP) $(KDIR)/image-$(dts).dtb $@.boot/$(dts).dtb;)
 	$(CP) $(IMAGE_KERNEL) $@.boot/$(KERNEL_NAME)
 	-$(CP) $@-boot.scr $@.boot/boot.scr
-	make_ext4fs -J -l $(CONFIG_TARGET_KERNEL_PARTSIZE)M $@.bootimg $@.boot
+	make_ext4fs -J -L kernel -l $(CONFIG_TARGET_KERNEL_PARTSIZE)M $@.bootimg $@.boot
 endef
 
 define Build/sdcard-img