Expanding root partition and filesystem

This article relies on the following:

Accessing web interface / command-line interface
Managing configs / packages / services / logs

extroot_configuration provides an alternative way of creating a exroot partition.

These instructions can be used to expand the root partition and filesystem of your OpenWrt install on an x86 target which was installed using ext4 or squashfs images.

Support ext4 and squashfs image types.
Automatically identify the root partition and filesystem.
Expand the root partition and filesystem using free space.
Preserve the scripts through firmware upgrade.
Automatically run after firmware upgrade.

The instructions below can be used to download and execute a script which will perform the expansion automatically.

Do not follow these instructions if you have an NVMe device. There is currently a long standing issue with NVMe devices where these instructions will effectively brick your install after the first reboot with error:

failed to execute /usr/libexec/login.

If you are using an NVMe device, you will need to use an installation method that doesn't require you to image your NVMe device and expand it. For example, manually creating partitions, installing grub, formatting the root partition and copying in the files from rootfs.tar.gz.

# Install packages
apk update
apk add parted losetup resize2fs blkid
 
# Download expand-root.sh
wget -U "" -O expand-root.sh "https://openwrt.org/_export/code/docs/guide-user/advanced/expand_root?codeblock=3"
chmod +x expand-root.sh
 
# Source the script (creates /etc/uci-defaults/70-rootpt-resize and /etc/uci-defaults/80-rootfs-resize, and adds them to /etc/sysupgrade.conf so they will be re-run after a sysupgrade)
. ./expand-root.sh
 
# Resize root partition and filesystem (will resize partiton, reboot resize filesystem, and reboot again)
sh /etc/uci-defaults/70-rootpt-resize

# Install packages
opkg update
opkg install parted losetup resize2fs blkid
 
# Download expand-root.sh
wget -U "" -O expand-root.sh "https://openwrt.org/_export/code/docs/guide-user/advanced/expand_root?codeblock=3"
 
# Source the script (creates /etc/uci-defaults/70-rootpt-resize and /etc/uci-defaults/80-rootpt-resize, and adds them to /etc/sysupgrade.conf so they will be re-run after a sysupgrade)
. ./expand-root.sh
 
# Resize root partition and filesystem (will resize partiton, reboot resize filesystem, and reboot again)
sh /etc/uci-defaults/70-rootpt-resize

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# Configure startup scripts
cat << "EOF" > /etc/uci-defaults/70-rootpt-resize
if [ ! -e /etc/rootpt-resize ] \
&& type parted > /dev/null \
&& lock -n /var/lock/root-resize
then
ROOT_BLK="$(readlink -f /sys/dev/block/"$(awk -e \
'$9=="/dev/root"{print $3}' /proc/self/mountinfo)")"
ROOT_DISK="/dev/$(basename "${ROOT_BLK%/*}")"
ROOT_PART="${ROOT_BLK##*[^0-9]}"
parted -f -s "${ROOT_DISK}" \
resizepart "${ROOT_PART}" 100%
mount_root done
touch /etc/rootpt-resize
 
if [ -e /boot/cmdline.txt ]
then 
NEW_UUID=`blkid ${ROOT_DISK}p${ROOT_PART} | sed -n 's/.*PARTUUID="\([^"]*\)".*/\1/p'`
sed -i "s/PARTUUID=[^ ]*/PARTUUID=${NEW_UUID}/" /boot/cmdline.txt
fi
 
reboot
fi
exit 1
EOF
cat << "EOF" > /etc/uci-defaults/80-rootfs-resize
if [ ! -e /etc/rootfs-resize ] \
&& [ -e /etc/rootpt-resize ] \
&& type losetup > /dev/null \
&& type resize2fs > /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}" "${ROOT_DEV}"
fi
resize2fs -f "${LOOP_DEV}"
mount_root done
touch /etc/rootfs-resize
reboot
fi
exit 1
EOF
cat << "EOF" >> /etc/sysupgrade.conf
/etc/uci-defaults/70-rootpt-resize
/etc/uci-defaults/80-rootfs-resize
EOF

OpenWrt Versions >= 25.12

# Install packages
apk update
apk add parted losetup resize2fs blkid
 
# Expand root partition/filesystem
sh /etc/uci-defaults/70-rootpt-resize

OpenWrt Version < 25.12

# Install packages
opkg update
opkg install parted losetup resize2fs blkid
 
# Expand root partition/filesystem
sh /etc/uci-defaults/70-rootpt-resize

If the root partition has already been expanded and the expand-root.sh script has previously run, attempting to run it again will not work by default. To perform an additional root expansion, you need remove previous script flags:

rm /etc/rootpt-resize
rm /etc/rootfs-resize

Open the /etc/sysupgrade.conf file and remove the following lines:

/etc/uci-defaults/70-rootpt-resize
/etc/uci-defaults/80-rootfs-resize

This ensures that the system no longer considers the scripts as already executed and then you can re-run script.

Expanding root partition and filesystem

Introduction

Features

Instructions

OpenWrt Versions >= 25.12

OpenWrt Versions < 25.12

Manual Instructions

Troubleshooting