Add overlay file system setup functions

This commit is contained in:
Simon Long 2019-10-01 10:53:22 +01:00
parent fa4185ac04
commit 5d7664812b

View File

@ -1787,6 +1787,230 @@ do_apply_os_config() {
return 0
}
get_overlay_now() {
grep -q "boot=overlay" /proc/cmdline
}
get_overlay_conf() {
grep -q "boot=overlay" /boot/cmdline.txt
}
get_bootro_now() {
findmnt /boot | grep -q " ro,"
}
get_bootro_conf() {
grep /boot /etc/fstab | grep -q "defaults.*,ro "
}
enable_overlayfs() {
KERN=$(uname -r)
INITRD=initrd.img-"$KERN"-overlay
# mount the boot partition as writable if it isn't already
if get_bootro_now ; then
if ! mount -o remount,rw /boot 2>/dev/null ; then
echo "Unable to mount boot partition as writable - cannot enable"
return
fi
BOOTRO=yes
else
BOOTRO=no
fi
# check that the modified initramfs is available for the current kernel version
if [ ! -e /boot/"$INITRD" ]; then
# generate the modified initramfs - check that the overlay file is available
if [ ! -e /etc/initramfs-tools/scripts/overlay ]; then
cat > /etc/initramfs-tools/scripts/overlay << 'EOF'
# Local filesystem mounting -*- shell-script -*-
#
# This script overrides local_mount_root() in /scripts/local
# and mounts root as a read-only filesystem with a temporary (rw)
# overlay filesystem.
#
. /scripts/local
local_mount_root()
{
local_top
local_device_setup "${ROOT}" "root file system"
ROOT="${DEV}"
# Get the root filesystem type if not set
if [ -z "${ROOTFSTYPE}" ]; then
FSTYPE=$(get_fstype "${ROOT}")
else
FSTYPE=${ROOTFSTYPE}
fi
local_premount
# CHANGES TO THE ORIGINAL FUNCTION BEGIN HERE
# N.B. this code still lacks error checking
modprobe ${FSTYPE}
checkfs ${ROOT} root "${FSTYPE}"
# Create directories for root and the overlay
mkdir /lower /upper
# Mount read-only root to /lower
if [ "${FSTYPE}" != "unknown" ]; then
mount -r -t ${FSTYPE} ${ROOTFLAGS} ${ROOT} /lower
else
mount -r ${ROOTFLAGS} ${ROOT} /lower
fi
modprobe overlay
# Mount a tmpfs for the overlay in /upper
mount -t tmpfs tmpfs /upper
mkdir /upper/data /upper/work
# Mount the final overlay-root in $rootmnt
mount -t overlay \
-olowerdir=/lower,upperdir=/upper/data,workdir=/upper/work \
overlay ${rootmnt}
}
EOF
fi
# add the overlay to the list of modules
if ! grep overlay /etc/initramfs-tools/modules > /dev/null; then
echo overlay >> /etc/initramfs-tools/modules
fi
# build the new initramfs
update-initramfs -c -k "$KERN"
# rename it so we know it has overlay added
mv /boot/initrd.img-"$KERN" /boot/"$INITRD"
fi
# there is now a modified initramfs ready for use...
# modify config.txt
sed -i /boot/config.txt -e "/initramfs.*/d"
echo initramfs "$INITRD" >> /boot/config.txt
# modify command line
if ! grep -q "boot=overlay" /boot/cmdline.txt ; then
sed -i /boot/cmdline.txt -e "s/^/boot=overlay /"
fi
if [ "$BOOTRO" = "yes" ] ; then
if ! mount -o remount,ro /boot 2>/dev/null ; then
echo "Unable to remount boot partition as read-only"
fi
fi
}
disable_overlayfs() {
# mount the boot partition as writable if it isn't already
if get_bootro_now ; then
if ! mount -o remount,rw /boot 2>/dev/null ; then
echo "Unable to mount boot partition as writable - cannot disable"
return
fi
BOOTRO=yes
else
BOOTRO=no
fi
# modify config.txt
sed -i /boot/config.txt -e "/initramfs.*/d"
# modify command line
sed -i /boot/cmdline.txt -e "s/\(.*\)boot=overlay \(.*\)/\1\2/"
if [ "$BOOTRO" = "yes" ] ; then
if ! mount -o remount,ro /boot 2>/dev/null ; then
echo "Unable to remount boot partition as read-only"
fi
fi
}
enable_bootro() {
sed -i /etc/fstab -e "s/\(.*\/boot.*\)defaults\(.*\)/\1defaults,ro\2/"
}
disable_bootro() {
sed -i /etc/fstab -e "s/\(.*\/boot.*\)defaults,ro\(.*\)/\1defaults\2/"
}
do_overlayfs() {
DEFAULT=--defaultno
CURRENT=0
STATUS="disabled"
if get_overlay_conf; then
DEFAULT=
CURRENT=1
STATUS="enabled"
fi
if [ "$INTERACTIVE" = True ]; then
whiptail --yesno "Would you like the overlay file system to be enabled?" $DEFAULT 20 60 2
RET=$?
else
RET=$1
fi
if [ $RET -eq $CURRENT ]; then
if [ $RET -eq 0 ]; then
enable_overlayfs
STATUS="enabled"
elif [ $RET -eq 1 ]; then
disable_overlayfs
STATUS="disabled"
else
return $RET
fi
ASK_TO_REBOOT=1
fi
if [ "$INTERACTIVE" = True ]; then
whiptail --msgbox "The overlay file system is $STATUS." 20 60 1
fi
if get_overlay_now ; then
if get_bootro_conf; then
BPRO="read-only"
else
BPRO="writable"
fi
whiptail --msgbox "The boot partition is currently $BPRO. This cannot be changed while an overlay file system is enabled." 20 60 1
else
DEFAULT=--defaultno
CURRENT=0
STATUS="writable"
if get_bootro_conf; then
DEFAULT=
CURRENT=1
STATUS="read-only"
fi
if [ "$INTERACTIVE" = True ]; then
whiptail --yesno "Would you like the boot partition to be write-protected?" $DEFAULT 20 60 2
RET=$?
else
RET=$1
fi
if [ $RET -eq $CURRENT ]; then
if [ $RET -eq 0 ]; then
enable_bootro
STATUS="read-only"
elif [ $RET -eq 1 ]; then
disable_bootro
STATUS="writable"
else
return $RET
fi
ASK_TO_REBOOT=1
fi
if [ "$INTERACTIVE" = True ]; then
whiptail --msgbox "The boot partition is $STATUS." 20 60 1
fi
fi
}
nonint() {
"$@"
}
@ -1909,6 +2133,7 @@ do_advanced_menu() {
"A7 GL Driver" "Enable/Disable experimental desktop GL driver" \
"A8 Compositor" "Enable/Disable xcompmgr composition manager" \
"A9 Pi 4 Video Output" "Video output options for Pi 4" \
"AA Overlay FS" "Enable/Disable read-only file system" \
3>&1 1>&2 2>&3)
RET=$?
if [ $RET -eq 1 ]; then
@ -1924,6 +2149,7 @@ do_advanced_menu() {
A7\ *) do_gldriver ;;
A8\ *) do_xcompmgr ;;
A9\ *) do_pi4video ;;
AA\ *) do_overlayfs ;;
*) whiptail --msgbox "Programmer error: unrecognized option" 20 60 1 ;;
esac || whiptail --msgbox "There was an error running option $FUN" 20 60 1
fi