Overlayroot not working with custom kernel
Problem
Overlayroot is not working with my custom kernel.
You can figure out the error message from /dev/.initramfs/overlayroot.log
$ cat /dev/.initramfs/overlayroot.log
builtin set cfgdisk='disabled'
swap=0 recurse=0 debug=0 dir=/overlay
device= mode=tmpfs
[warning]: configuring overlayroot with mode=tmpfs opts='recurse=0' per /dev/disk/by-uuid/54bccbc9-642f-432a-ac58-e131b14babb9/etc/overlayroot.conf
[failure]: missing kernel module overlayfs
Solution
Replace the name of kernel module: «overlayfs» to «overlay».
You need to modify two script files: /usr/share/initramfs-tools/hooks/overlayroot and /usr/share/initramfs-tools/scripts/init-bottom/overlayroot.
Refer to the following two scripts.
Overlayroot hooks script
It will replace the file: /usr/share/initramfs-tools/hooks/overlayroot.
#!/bin/sh
set -e
PREREQS="cryptsetup"
case $1 in
prereqs) echo "${PREREQS}"; exit 0;;
esac
. /usr/share/initramfs-tools/hook-functions
##
copy_exec /usr/bin/head /bin
copy_exec /usr/bin/sha512sum /bin
copy_exec /sbin/wipefs /sbin
copy_exec /sbin/cryptsetup /sbin
copy_exec /sbin/mke2fs /sbin
#manual_add_modules overlayfs
manual_add_modules overlay
manual_add_modules dm_mod
manual_add_modules dm_crypt
# this is '||' only in case this module isn't built
manual_add_modules aesni_intel || true
# Grab as much true random data as possible, up to 4KB, and stash it into a
# random seed in the initramfs
dd if=/dev/random of="${DESTDIR}/.random-seed" bs=1 count=4096 iflag=nonblock >/dev/null 2>&1 || true
# vi: ts=4 noexpandtab
Overlayroot init-bottom script
It will replace the file: /usr/share/initramfs-tools/scripts/init-bottom/overlayroot.
#!/bin/sh
# Copyright, 2012 Dustin Kirkland <kirkland@ubuntu.com>
# Copyright, 2012 Scott Moser <smoser@ubuntu.com>
# Copyright, 2012 Axel Heider
#
# Based on scripts from
# Sebastian P.
# Nicholas A. Schembri State College PA USA
# Axel Heider
# Dustin Kirkland
# Scott Moser
#
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see
# <http://www.gnu.org/licenses/>.
case "$1" in
# no pre-reqs
prereqs) echo ""; exit 0;;
esac
. /scripts/functions
PATH=/usr/sbin:/usr/bin:/sbin:/bin
MYTAG="overlayroot"
TEMP_D="${TMPDIR:-/tmp}/${0##*/}.configs"
VARIABLES="overlayroot overlayroot_cfgdisk"
# generic settings
# ${ROOT} and ${rootmnt} are predefined by caller of this script. Note that
# the root fs ${rootmnt} it mounted readonly on the initrams, which fits
# nicely for our purposes.
root_rw=/media/root-rw
root_ro=/media/root-ro
ROOTMNT=${rootmnt} # use global name to indicate created outside this
OVERLAYROOT_DEBUG=0
log() {
"log_${1}_msg" "$MYTAG: $2";
_debug "[$1]:" "$2"
}
log_fail() { log failure "$*"; }
log_success() { log success "$*"; }
log_warn() { log warning "$*"; }
fail() {
[ $# -eq 0 ] || log_fail "$@";
exit 0; # why do we exit success?
}
cleanup() {
[ -d "${TEMP_D}" ] && rm -Rf "${TEMP_D}"
}
debug() {
_debug "$@"
[ "${OVERLAYROOT_DEBUG:-0}" = "0" ] && return
echo "$MYTAG:" "$@"
}
_debug() {
if [ "${DEBUG_BUSTED:-0}" = "0" ]; then
{ echo "$@" >> "/dev/.initramfs/${MYTAG}.log"; } 2>/dev/null ||
{ DEBUG_BUSTED=1; log_warn "debug is busted"; }
fi
}
safe_string() {
local prev="$1" allowed="$2" cur=""
[ -n "$prev" ] || return 1
while cur="${prev#[${allowed}]}"; do
[ -z "$cur" ] && return 0
[ "$cur" = "$prev" ] && break
prev="$cur"
done
return 1
}
parse_string() {
# parse a key/value string like:
# name=mapper,pass=foo,fstype=ext4,mkfs=1
# set variables under namespace 'ns'.
# _RET_name=mapper
# _RET_pass=foo
# _RET_fstype=ext4
# set _RET to the list of variables found
local input="${1}" delim="${2:-,}" ns="${3:-_RET_}"
local oifs="$IFS" tok="" keys="" key="" val=""
set -f; IFS="$delim"; set -- $input; IFS="$oifs"; set +f;
_RET=""
for tok in "$@"; do
key="${tok%%=*}"
val="${tok#${key}}"
val=${val#=}
safe_string "$key" "0-9a-zA-Z_" ||
{ debug "$key not a safe variable name"; return 1; }
eval "${ns}${key}"='${val}' || return 1
keys="${keys} ${ns}${key}"
done
_RET=${keys# }
return
}
get_varval() { eval _RET='${'$1'}'; }
write_kernel_cmdline_cfg() {
local cfg="$1" desc="${2:-kernel cmdline}"
local cmdline="" var=""
read cmdline < /proc/cmdline || return 1
: > "${cfg}" || return
set -f
{
echo "desc='${desc}'"
for tok in $cmdline; do
for var in $VARIABLES; do
if [ "$tok" = "$var" ]; then
log_warn "kernel param without value '${tok}'";
continue;
elif [ "${tok}" = "${var}=" ]; then
echo "${var}=''";
elif [ "${tok#${var}=}" != "${tok}" ]; then
echo "${var}='${tok#${var}=}'"
fi
done
done
} >> "$cfg"
set +f
}
wait_for_dev() {
local dev="$1" timeout="${2:-0}"
[ -b "$dev" ] && return 0
[ "$timeout" = "0" ] && return 1
# wait-for-root writes fstype to stdout, redirect to null
wait-for-root "$dev" "$timeout" >/dev/null
}
crypto_setup() {
local fstype="ext4" pass="" mapname="secure" mkfs="1" dev=""
local timeout=0
local entropy_sources="/proc/sys/kernel/random/boot_id /proc/sys/kernel/random/uuid /dev/urandom"
local seed=
# Seed the psuedo random number generator with available seeds
for seed in "/.random-seed" "${ROOTMNT}/var/lib/urandom/random-seed"; do
[ -f "${seed}" ] && cat "${seed}" > /dev/urandom ||
{ debug "missing rng seed [${seed}]"; }
done
# this does necessary crypto setup and sets _RET
# to the appropriate block device (ie /dev/mapper/secure)
# mkfs (default is 1):
# 0: never create filesystem
# 1: if pass is given and mount fails, create a new one
# if no pass given, create new
# 2: if pass is given and mount fails, fail
# if no pass given, create new
local options="$1"
parse_string "${options}" ||
{ log_fail "failed parsing '${options}'"; return 1; }
fstype=${_RET_fstype:-${fstype}}
pass=${_RET_pass:-${pass}}
mapname=${_RET_mapname:-${mapname}}
mkfs=${_RET_mkfs:-${mkfs}}
dev=${_RET_dev:-${dev}}
timeout=${_RET_timeout:-${timeout}}
[ -n "$dev" ] ||
{ log_fail "dev= argument not provided in '${options}'"; return 1; }
short2dev "$dev" ||
{ log_fail "failed to convert $dev to a device"; return 1; }
dev="${_RET}"
debug "fstype=${fstype} pass=${pass} mapname=${mapname}"
debug "mkfs=${mkfs} dev=${dev} timeout=${timeout}"
wait_for_dev "$dev" "$timeout" || {
log_fail "crypt dev device $dev does not exist after ${timeout}s";
return 1;
}
if [ -n "$pass" ]; then
printf "%s" "$pass" |
cryptsetup luksOpen "$dev" "$mapname" --key-file -
if [ $? -eq 0 ]; then
local tdev="/dev/mapper/$mapname"
log_warn "reusing existing luks device at $dev"
wait_for_dev "$tdev" 20 ||
{ log_fail "$tdev did not appear"; return 1; }
_RET_DEVICE="/dev/mapper/$mapname"
return 0
fi
if [ "$mkfs" != "1" ]; then
log_fail "luksOpen failed on $dev with mkfs=$mkfs";
return 1;
fi
log_warn "re-opening $dev failed with mkfs=$mkfs will create new"
else
[ "$mkfs" = "0" ] &&
{ log_fail "mkfs=0, but no password provided"; return 1; }
entropy_sources="$entropy_sources $dev"
local pass_file=$(mktemp /dev/.initramfs/${MYTAG}.XXXXXX) ||
{ log_fail "failed creation of password file"; return 1; }
stat -L /dev/* /proc/* /sys/* >${pass_file} 2>&1 ||
{ log_warn "could not seed with stat entropy [$entropy_sources]"; }
head -c 4096 $entropy_sources >> ${pass_file} ||
{ log_fail "failed reading entropy [$entropy_sources]"; return 1; }
pass=$(sha512sum ${pass_file}) ||
{ log_fail "failed generation of password"; return 1; }
pass=${pass%% *}
printf "%s" "${pass}" > ${pass_file}
fi
log_warn "setting up new luks device at $dev"
# clear backing device
wipefs -a "$dev" ||
{ log_fail "failed to wipe $dev"; return 1; }
printf "%s" "$pass" | cryptsetup luksFormat "$dev" --key-file - ||
{ log_fail "luksFormat $dev failed"; return 1; }
printf "%s" "$pass" |
cryptsetup luksOpen "$dev" "$mapname" --key-file - ||
{ log_fail "luksOpen $dev failed"; return 1; }
mke2fs -t "${fstype}" "/dev/mapper/${mapname}" || {
log_fail "failed to mkfs -t $fstype on map $mapname";
return 1;
}
_RET_DEVICE="/dev/mapper/$mapname"
return 0
}
dev_setup() {
local options="$1" dev="" timeout=0 path="/"
# options supported:
# dev=device,timeout=X,path=/
parse_string "${options}" ||
{ log_fail "failed parsing '${options}'"; return 1; }
dev=${_RET_dev:-${dev}}
timeout=${_RET_timeout:-${timeout}}
[ -n "$dev" ] ||
{ log_fail "dev= argument not provided in '${options}'"; return 1; }
short2dev "$dev" ||
{ log_fail "failed to convert $dev to a device"; return 1; }
dev="${_RET}"
debug "dev=${dev} timeout=${timeout}"
wait_for_dev "$dev" "$timeout"
_RET_DEVICE="$dev"
}
overlayrootify_fstab() {
# overlayrootify_fstab(input, root_ro, root_rw, dir_prefix, recurse, swap)
# read input fstab file, write an overlayroot version to stdout
# also returns (_RET) a list of directories that will need to be made
local input="$1" root_ro="${2:-/media/root-ro}"
local root_rw="${3:-/media/root-rw}" dir_prefix="${4:-/}"
local recurse=${5:-1} swap=${6:-0}
local hash="#" oline="" ospec="" upper="" dirs="" copy_opts=""
local vfstypes=" proc sys tmpfs dev udev "
local spec file vfstype opts pass freq line ro_line
dir_prefix="${dir_prefix#/}"
[ -f "$input" ] || return 1
while read spec file vfstype opts pass freq; do
line="$spec $file $vfstype $opts $pass $freq"
case ",$opts," in
*,ro,*) ro_opts="$opts";;
*) ro_opts="ro,${opts}";;
esac
ro_line="$spec ${root_ro}$file $vfstype ${ro_opts} $pass $freq"
if [ "${spec#${hash}}" != "$spec" ] ||
[ -z "$freq" ]; then
# line has a comment in first field, or not 6 fields
echo "$line"
elif [ "${vfstypes# *${vfstype} }" != "${vfstypes}" ]; then
# this is a virtual filesystem, just let it through
echo "${line}"
elif [ "$vfstype" = "swap" ]; then
if [ "$swap" = "0" ]; then
# comment out swap lines
echo "#overlayroot:swap=${swap}#${line}"
elif [ "${spec#/}" != "${spec}" ] &&
[ "${spec#/dev/}" = "${spec}" ]; then
# comment out swap files (spec starts with / and not in /dev)
echo "#overlayroot:swapfile#${line}"
else
echo "${line}"
fi
else
ospec="${root_ro}${file}"
copy_opts=""
[ "${opts#*nobootwait*}" != "${opts}" ] &&
copy_opts=",nobootwait"
upper="${root_rw%/}/${dir_prefix%/}${file%/}"
oline="${ospec} ${file} overlay "
oline="${oline}lowerdir=${root_ro}${file},"
oline="${oline}upperdir=${upper}${copy_opts} $pass $freq"
if [ "$recurse" != "0" ]; then
echo "$ro_line"
echo "$oline"
dirs="${dirs} ${upper}"
else
echo "$line"
[ "$file" = "/" ] && dirs="${dirs} ${upper}"
fi
fi
done < "$input"
_RET=${dirs# }
}
short2dev() {
# turn 'LABEL=' or 'UUID=' into a device path
# also support /dev/* and 'vdb' or 'xvda'
local input="$1" oifs="$IFS" dev newdev s
case "$input" in
LABEL=*)
dev="${input#LABEL=}"
case "${dev}" in
*/*) dev="$(echo "${dev}" | sed 's,/,\x2f,g')";;
esac
dev="/dev/disk/by-label/${dev}"
;;
UUID=*) dev="/dev/disk/by-uuid/${input#UUID=}" ;;
/dev/*) dev="${input}";;
*) dev="/dev/${input}";;
esac
_RET=$dev
}
get_cfg() {
# get_cfg(device, file, cfg, timeout=0)
# copy the file $cfg off $device to $file, waiting $timeout for
# $device to appear
local dev="$1" file="$2" cfg="${3:-overlayroot.conf}" timeout="${4:-0}"
local cfgdev="" success=0 didmnt=false mp="" pre="get_cfg($dev):"
[ -z "$dev" ] && return 1
if [ "$timeout" != "0" ]; then
wait_for_dev "$dev" "$timeout" ||
{ debug "$pre did not appear in $timeout"; return 1; }
else
udevadm settle
fi
short2dev "$dev" && cfgdev="$_RET" && [ -b "$cfgdev" ] ||
{ debug "$pre not present"; return 1; }
if mp="${TEMP_D}/mp" && mkdir "$mp" &&
mount -o ro "$cfgdev" "$mp"; then
if [ -f "$mp/$cfg" ]; then
cp "$mp/$cfg" "$file" && success=1 ||
debug "$pre copy failed"
else
debug "$pre '$file' file not found"
fi
umount "$mp"
else
debug "$pre mount failed"
fi
[ -d "$mp" ] || rmdir "$mp"
[ $success -eq 1 ] || return 1
_RET="$dev/$cfg"
}
parse_cfg() {
# parse_cfg($file,$desc,$vars)
# this reasonably safely sources the "config" file $file
# and then declares the variables listed to stdout
#
# known issues:
# * sourced file could re-define 'echo'
# * just fails if a value has a ' in it
[ -f "$1" ] || return 0
tick="'" sh -c '
__tick=$tick
__file=$1; __desc=$2;
__unset__="__unset__"
shift 2
__vars="$*"
readonly __tick __file __desc __vars
. "${__file}"
if [ $? -ne 0 ]; then
echo "failed source "${__file}" ($__desc)" 1>&2
return 1
fi
set -e
echo "desc=${__tick}${__desc}${__tick}"
for var in ${__vars}; do
eval val=${${var}-${__unset__}} ||
{ echo "eval of $var failed"; exit 1; }
[ "${val#*${__tick}}" = "${val}" ] || {
echo "variable "$var" had single tick in it. fail";
exit 1;
}
[ "${val}" = "${__unset__}" ] ||
echo "$var=${__tick}${val}${__tick}"
done
' -- "$@"
}
readcfgd() {
local cfg_d="$1"
# this kind of stinks, each VARIABLE goes into global scope
local or="" or_cfgdisk=""
_RET_desc_oroot=""
_RET_desc_cfgdisk=""
set +f
for f in "${cfg_d}"/*; do
. "$f" || fail "failed reading $f"
[ "$or" != "${overlayroot}" ] &&
_RET_desc_oroot="$desc"
[ "${or_cfgdisk}" != "${overlayroot_cfgdisk}" ] &&
_RET_desc_cfgdisk="$desc"
or=${overlayroot}
or_cfgdisk=${overlayroot_cfgdisk}
done
set -f
}
fix_upstart_overlayfs() {
# inotify events on an overlayfs underlay do not propogate through
# a newly created overlay. This causes job creation and deletion issues
# for upstart, which uses inotify on /etc/init. So ensure that the overlay
# explicitly has a /etc/init (LP: #1213925)
local root="$1"
local initctl="$root/sbin/initctl"
local eifile="/etc/init/.overlayfs-upstart-helper"
[ -e "$initctl" -o -L "$initctl" ] || return 0
[ -d "$root/etc/init" ] || return 0
echo "#upstart needs help for overlayfs (LP: #1213925)."
> "$root/$eifile" ||
{ log_fail "failed to write $root/$eifile"; return 1; }
debug "created $eifile under $root (LP: #1213925)"
}
cfgd="${TEMP_D}/configs"
mkdir -p "${cfgd}" || fail "failed to create tempdir"
trap cleanup EXIT
# collect the different config locations into a file
# write individual config files in $cfgd that contain
{
echo "desc='builtin'"
echo "overlayroot=''"
echo "overlayroot_cfgdisk='disabled'"
} > "$cfgd/00-builtin"
write_kernel_cmdline_cfg "${cfgd}/90-kernel" ||
fail "failed to read kernel command line!"
parse_cfg "/conf/conf.d/overlayroot" "initramfs config"
"$VARIABLES" > "${cfgd}/10-initramfs" ||
fail "failed parsing initramfs config"
parse_cfg "${ROOTMNT}/etc/overlayroot.conf" "$ROOT/etc/overlayroot.conf"
"$VARIABLES" > "${cfgd}/20-root-config" ||
fail "failed parsing root config"
parse_cfg "${ROOTMNT}/etc/overlayroot.local.conf"
"$ROOT/etc/overlayroot.local.conf"
"$VARIABLES" > "${cfgd}/30-root-local-config" ||
fail "failed parsing root config"
# now read the trusted configs, to see if overlayroot_cfgdisk is set
readcfgd "$cfgd" ||
fail "reading configs failed"
used_desc="${_RET_desc_oroot}"
[ -n "${_RET_desc_cfgdisk}" ] &&
debug "${_RET_desc_cfgdisk} set cfgdisk='${overlayroot_cfgdisk}'"
# if one of the trusted configs above gave us set the overlayroot_cfgdisk
# variable, then look for such a device and read a config from it.
cfgdisk=0
if [ "${overlayroot_cfgdisk:-disabled}" != "disabled" ] &&
get_cfg "${overlayroot_cfgdisk}" "${TEMP_D}/cfgdisk"; then
desc=${_RET}
parse_cfg "${TEMP_D}/cfgdisk" "${desc}" "$VARIABLES"
> "${cfgd}/80-cfgdisk" ||
fail "reading config from ${desc} failed"
used_desc="${_RET_desc_oroot}"
# now read the parsed configs again.
readcfgd "$cfgd" ||
fail "reading configs failed"
[ -n "${_RET_desc_cfgdisk}" ] &&
debug "${_RET_desc_cfgdisk} set cfgdisk=${overlayroot_cfgdisk}"
[ -n "${_RET_desc_oroot}" ] &&
debug "${_RET_desc_oroot} set overlayroot=${overlayroot}"
fi
opts=""
cfgmsg="${used_desc:+ (per ${used_desc})}"
case "${overlayroot:-disabled}" in
tmpfs|tmpfs:*)
mode="tmpfs"
opts="${overlayroot#tmpfs}";
opts=${opts#:}
;;
/dev/*|device:*)
case "$overlayroot" in
/dev/*) opts="dev=${overlayroot}";;
*) opts="${overlayroot#device:}";;
esac
dev_setup "${opts}" ||
fail "failed setup overlay for ${overlayroot} [$opts]${cfgmsg}"
mode="device"
device="$_RET_DEVICE"
;;
crypt:*)
mode="crypt"
opts=${overlayroot#crypt:}
crypto_setup "${opts}" ||
fail "failed setup crypt for ${overlayroot}${cfgmsg}"
device="$_RET_DEVICE"
;;
disabled)
debug "overlayroot disabled${cfgmsg}"
exit 0;;
*)
fail "invalid value for overlayroot: ${overlayroot}${cfgmsg}"
exit 0;;
esac
parse_string "$opts" "," _RET_common_
swap=${_RET_common_swap:-0}
recurse=${_RET_common_recurse:-1}
OVERLAYROOT_DEBUG=${_RET_common_debug:-${OVERLAYROOT_DEBUG}}
dir_prefix=${_RET_common_dir:-"/overlay"}
debug "swap=$swap recurse=$recurse debug=$OVERLAYROOT_DEBUG dir=$dir_prefix"
debug "device=$device mode=$mode"
[ "$swap" = "0" -o "$swap" = "1" ] ||
fail "invalid setting for swap: $swap. must be '0' or '1'"
[ "$recurse" = "0" -o "$recurse" = "1" ] ||
fail "invalid setting for recurse: $recurse. must be '0' or '1'"
log_warn "configuring overlayroot with mode=$mode opts='$opts' per $used_desc"
# overlayroot_driver *could* be defined in one of the configs above
# but we're not documenting that.
overlayroot_driver=${overlayroot_driver:-overlay}
# settings based on overlayroot_driver
workdir=""
case "${overlayroot_driver}" in
overlay)
mount_type="overlay"
mount_opts="-o lowerdir=${root_ro},upperdir=${root_rw}/${dir_prefix}"
# 3.18+ require 'workdir=' option.
case "$(uname -r)" in
2*|3.1[01234567]*|3.[0-9].*) :;;
*)
workdir="${dir_prefix%/}-workdir"
mount_opts="${mount_opts},workdir=${root_rw}/${workdir}";;
esac
mount_opts="${mount_opts} overlayroot ${ROOTMNT}"
;;
aufs)
mount_type="aufs"
mount_opts="-o dirs=${root_rw}/${dir_prefix}:${root_ro}=ro aufs-root ${ROOTMNT}"
;;
*)
log_fail "invalid overlayroot driver: ${overlayroot_driver}"
panic "$MYTAG"
;;
esac
# check if kernel module exists
modprobe -qb "${overlayroot_driver}" ||
fail "missing kernel module ${overlayroot_driver}"
# make the mount point on the init root fs ${root_rw}
mkdir -p "${root_rw}" ||
fail "failed to create ${root_rw}"
# make the mount point on the init root fs ${root_ro}
mkdir -p "${root_ro}" ||
fail "failed to create ${root_ro}"
# mount the backing device to $root_rw
if [ "$mode" = "tmpfs" ]; then
# mount a tmpfs using the device name tmpfs-root
mount -t tmpfs tmpfs-root "${root_rw}" ||
fail "failed to create tmpfs"
else
# dev or crypto
mount "$device" "${root_rw}" ||
fail "failed mount backing device $device"
fi
mkdir -p "${root_rw}/${dir_prefix}" ||
fail "failed to create ${dir_prefix} on ${device}"
[ -z "$workdir" ] || mkdir -p "$root_rw/${workdir}" ||
fail "failed to create workdir '$workdir' on ${device}"
# root is mounted on ${ROOTMNT}, move it to ${ROOT_RO}.
mount --move "${ROOTMNT}" "${root_ro}" ||
fail "failed to move root away from ${ROOTMNT} to ${root_ro}"
# there is nothing left at ${ROOTMNT} now. So for any error we get we should
# either do recovery to restore ${ROOTMNT} for drop to a initramfs shell using
# "panic". Otherwise the boot process is very likely to fail with even more
# errors and leave the system in a wired state.
# mount virtual fs ${ROOTMNT} with rw-fs ${root_rw} on top or ro-fs ${root_ro}.
debug mount -t "$mount_type" $mount_opts
mount -t "$mount_type" $mount_opts
if [ $? -ne 0 ]; then
log_fail "failed to create new ro/rw layered ${ROOTMNT}"
log_fail "mount command was: mount -t $mount_type $mount_opts"
# do recovery and try resoring the mount for ${ROOTMNT}
mount --move ${root_ro} ${ROOTMNT}
if [ $? -ne 0 ]; then
# thats bad, drop to shell to let the user try fixing this
log_fail "RECOVERY_ERROR: failed to move $root_ro back to ${ROOTMNT}"
panic "$MYTAG"
fi
exit 0
fi
# now the real root fs is on ${root_ro} of the init file system, our
# layered root fs is set up at ${ROOTMNT}. So we can write anywhere in
# {ROOTMNT} and the changes will end up in ${root_rw} while ${root_ro} it
# not touched. However ${root_ro} and ${root_rw} are on the initramfs root
# fs, which will be removed an replaced by ${ROOTMNT}. Thus we must move
# ${root_ro} and ${root_rw} to the rootfs visible later, ie.
# ${ROOTMNT}${root_ro} and ${ROOTMNT}${root_ro}. Since the layered ro/rw
# is already up, these changes also end up on ${root_rw} while ${root_ro}
# is not touched.
# move mount from ${root_ro} to ${ROOTMNT}${root_ro}
mkdir -p "${ROOTMNT}/${root_ro}"
mount --move ${root_ro} "${ROOTMNT}${root_ro}" ||
fail "failed to move ${root_ro} to ${ROOTMNT}${root_ro}"
# move mount from ${root_rw} to ${ROOTMNT}${root_rw}
[ -d ${ROOTMNT}${root_rw} ] || mkdir -p ${ROOTMNT}${root_rw}
mount --move "${root_rw}" "${ROOTMNT}${root_rw}" ||
fail "failed to move ${root_rw} to ${ROOTMNT}${root_rw}"
# technically, everything is set up nicely now. Since ${ROOTMNT} had beend
# mounted read-only on the initfamfs already, ${ROOTMNT}${root_ro} is it,
# too. Now we init process could run - but unfortunately, we may have to
# prepare some more things here.
# Basically, there are two ways to deal with the read-only root fs. If the
# system is made aware of this, things can be simplified a lot. If it is
# not, things need to be done to our best knowledge.
#
# So we assume here, the system does not really know about our read-only
# root fs.
#
# Let's deal with /etc/fstab first. It usually contains an entry for the
# root fs, which is no longer valid now. We have to remove it and add our
# new ${root_ro} entry.
# Remember we are still on the initramfs root fs here, so we have to work
# on ${ROOTMNT}/etc/fstab. The original fstab is
# ${ROOTMNT}${root_ro}/etc/fstab.
cat <<EOF >${ROOTMNT}/etc/fstab
#
# This fstab is in an overlayfs. The real one can be found at
# ${root_ro}/etc/fstab
# The original entry for '/' and other mounts have been updated to be placed
# under $root_ro.
# To permanently modify this (or any other file), you should change-root into
# a writable view of the underlying filesystem using:
# sudo overlayroot-chroot
#
EOF
[ $? -eq 0 ] || log_fail "failed to modify /etc/fstab (step 1)"
overlayrootify_fstab ""${ROOTMNT}${root_ro}/etc/fstab"" "$root_ro"
"$root_rw" "$dir_prefix" "$recurse" "$swap" >> "${ROOTMNT}/etc/fstab" ||
log_fail "failed to modify /etc/fstab (step 2)"
# we have to make the directories in ${root_rw} because if they do not
# exist, then the 'upper=' argument to overlayfs will fail.
for d in ${_RET}; do
mkdir -p "${ROOTMNT}/$d"
done
if [ "${overlayroot_driver}" = "overlay" ]; then
fix_upstart_overlayfs "$ROOTMNT" ||
log_fail "failed to fix upstart for overlayfs"
fi
# if / is supposed to be mounted read-only (cmdline with 'ro')
# then mount our overlayfs as read-only just to be more normal
read cmdline < /proc/cmdline
cmdline=" $cmdline "
if [ "${cmdline#* ro }" != "$cmdline" ]; then
mount -o remount,ro "$ROOTMNT" ||
log_fail "failed to remount overlayroot read-only"
debug "mounted $ROOTMNT read-only per kernel cmdline"
fi
msg="configured root with '$overlayroot' using ${overlayroot_driver} per"
msg="$msg ${used_desc}"
log_success "$msg"
exit 0
# vi: ts=4 noexpandtab