Adopt the solution for resizing root from openwrt expand_root guide

Closes: #37

defaults/70-rootpt-resize

@@ -12,8 +12,7 @@ parted -l ---pretend-input-tty << EOI
 ok
 fix
 EOI
-parted -s "${ROOT_DISK}" \
-resizepart "${ROOT_PART}" 100%
+parted -s "${ROOT_DISK}" resizepart "${ROOT_PART}" 100%
 mount_root done
 touch /etc/rootpt-resize
 reboot

defaults/80-rootfs-resize

@@ -1,4 +1,6 @@
 # Copied from https://openwrt.org/docs/guide-user/advanced/expand_root
+# Updated for f2fs using
+# https://github.com/anaelorlinski/OpenWrt-NanoPi-R2S-R4S-Builds/blob/main/docs/resize-f2fs.md
 
 if [ ! -e /etc/rootfs-resize ] \
 && [ -e /etc/rootpt-resize ] \
@@ -6,19 +8,16 @@ if [ ! -e /etc/rootfs-resize ] \
 && type resize.f2fs > /dev/null \
 && lock -n /var/lock/root-resize
 then
-ROOT_BLK="$(readlink -f /sys/dev/block/"$(awk -e \
-'$9=="/dev/root"{print $3}' /proc/self/mountinfo)")"
-ROOT_DEV="/dev/${ROOT_BLK##*/}"
-LOOP_DEV="$(awk -e '$5=="/overlay"{print $9}' \
-/proc/self/mountinfo)"
-if [ -z "${LOOP_DEV}" ]
-then
-LOOP_DEV="$(losetup -f)"
-losetup "${LOOP_DEV}" "${ROOT_DEV}"
-fi
-resize.f2fs "${LOOP_DEV}"
-mount_root done
-touch /etc/rootfs-resize
+LOOP="$(losetup -n -O NAME | sort | sed -n -e "1p")"
+ROOT="$(losetup -n -O BACK-FILE ${LOOP} | sed -e "s|^|/dev|")"
+OFFS="$(losetup -n -O OFFSET ${LOOP})"
+LOOP="$(losetup -f)"
+losetup -o ${OFFS} ${LOOP} ${ROOT}
+fsck.f2fs -f ${LOOP}
+mount ${LOOP} /mnt
+touch /mnt/upper/etc/rootfs-resize
+umount ${LOOP}
+resize.f2fs ${LOOP}
 reboot
 fi
 exit 1