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October 6, 2022 18:31
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/etc/initramfs-tools/scripts/overlay
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# /etc/initramfs-tools/scripts/overlay | |
# default file generated by /usr/bin/raspi-config | |
# add highlighted lines to access lower and upper filesystems | |
# 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} ${ROOT} /lower | |
fi | |
modprobe overlay || insmod "/lower/lib/modules/$(uname -r)/kernel/fs/overlayfs/overlay.ko" | |
# 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} | |
############ ADD THIS TO ACCESS OVERLAYS ########### | |
mkdir ${rootmnt}/.ro | |
mount --bind /lower ${rootmnt}/.ro | |
mkdir ${rootmnt}/.rw | |
mount --bind /upper ${rootmnt}/.rw | |
#################################################### | |
} |
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