From 8f7c332e488f88e5845a3c7954af7934c2f1e37b Mon Sep 17 00:00:00 2001 From: Kairui Song Date: Mon, 15 Feb 2021 23:08:47 +0800 Subject: [PATCH] refactor(squash): structure in a cleaner way Simplify the squash mount layout. Instead of overlay on each top directory (/etc, /usr), just mount and switch_root into the squash image, with a overlay on top of it. Also install the binaries and setup scripts separately, so the squash setup code and the squash image content is independent of each other, all squash setup script and binaries can be deleted safely upon switch_root. With this change, previous squash clean up service and other tricky implementations are all gone. This commit depends on systemd commits from: https://github.com/systemd/systemd/pull/18124 Previouly systemd doesn't recognize non-ramfs initramfs, now this is doable with SYSTEMD_IN_INITRD=lenient Signed-off-by: Kairui Song --- dracut-initramfs-restore.sh | 4 +- dracut.sh | 4 +- lsinitrd.sh | 2 +- modules.d/99squash/clear-squash.sh | 6 -- modules.d/99squash/init-squash.sh | 70 ++++++--------------- modules.d/99squash/module-setup.sh | 56 ++++++----------- modules.d/99squash/squash-mnt-clear.service | 17 ----- 7 files changed, 42 insertions(+), 117 deletions(-) delete mode 100755 modules.d/99squash/clear-squash.sh delete mode 100644 modules.d/99squash/squash-mnt-clear.service diff --git a/dracut-initramfs-restore.sh b/dracut-initramfs-restore.sh index ff6c3869..1feec108 100644 --- a/dracut-initramfs-restore.sh +++ b/dracut-initramfs-restore.sh @@ -48,9 +48,9 @@ else fi if [[ -d squash ]]; then - unsquashfs -no-xattrs -f -d . squash/root.img >/dev/null + unsquashfs -no-xattrs -f -d . squash-root.img >/dev/null if [ $? -ne 0 ]; then - echo "Squash module is enabled for this initramfs but failed to unpack squash/root.img" >&2 + echo "Squash module is enabled for this initramfs but failed to unpack squash-root.img" >&2 rm -f -- /run/initramfs/shutdown exit 1 fi diff --git a/dracut.sh b/dracut.sh index 184e4769..421fc1b1 100755 --- a/dracut.sh +++ b/dracut.sh @@ -2057,8 +2057,8 @@ fi if dracut_module_included "squash"; then readonly squash_dir="$initdir/squash/root" - readonly squash_img="$initdir/squash/root.img" - + readonly squash_img="$initdir/squash-root.img" + mkdir -p "$squash_dir" dinfo "*** Install squash loader ***" DRACUT_SQUASH_POST_INST=1 module_install "squash" fi diff --git a/lsinitrd.sh b/lsinitrd.sh index ffdb4a4f..66cfa9bc 100755 --- a/lsinitrd.sh +++ b/lsinitrd.sh @@ -169,7 +169,7 @@ list_files() list_squash_content() { - SQUASH_IMG="squash/root.img" + SQUASH_IMG="squash-root.img" SQUASH_TMPFILE="$TMPDIR/initrd.root.sqsh" $CAT "$image" 2>/dev/null | cpio --extract --verbose --quiet --to-stdout -- \ diff --git a/modules.d/99squash/clear-squash.sh b/modules.d/99squash/clear-squash.sh deleted file mode 100755 index 4f357817..00000000 --- a/modules.d/99squash/clear-squash.sh +++ /dev/null @@ -1,6 +0,0 @@ -#!/bin/bash -mnt="/squash/root" -for dir in jsquash/root/*; do - mnt="$mnt ${dir#$SQUASH_MNT}" -done -umount --lazy -- $mnt diff --git a/modules.d/99squash/init-squash.sh b/modules.d/99squash/init-squash.sh index fee0105e..3de6f819 100755 --- a/modules.d/99squash/init-squash.sh +++ b/modules.d/99squash/init-squash.sh @@ -1,61 +1,29 @@ -#!/bin/bash +#!/bin/sh PATH=/bin:/sbin -SQUASH_IMG=/squash/root.img -SQUASH_MNT=/squash/root +# Basic mounts for mounting a squash image +mkdir /proc /sys /dev /run +mount -t proc -o nosuid,noexec,nodev proc /proc +mount -t sysfs -o nosuid,noexec,nodev sysfs /sys +mount -t devtmpfs -o mode=755,noexec,nosuid,strictatime devtmpfs /dev +mount -t tmpfs -o mode=755,nodev,nosuid,strictatime tmpfs /run -# Following mount points are neccessary for mounting a squash image - -[ ! -d /proc/self ] && \ - mount -t proc -o nosuid,noexec,nodev proc /proc - -[ ! -d /sys/kernel ] && \ - mount -t sysfs -o nosuid,noexec,nodev sysfs /sys - -[ ! -e /dev/loop-control ] && \ - mount -t devtmpfs -o mode=0755,noexec,nosuid,strictatime devtmpfs /dev - -# Need a loop device backend, overlayfs, and squashfs module +# Load required modules modprobe loop -if [ $? != 0 ]; then - echo "Unable to setup loop module" -fi - modprobe squashfs -if [ $? != 0 ]; then - echo "Unable to setup squashfs module" -fi - modprobe overlay -if [ $? != 0 ]; then - echo "Unable to setup overlay module" -fi -[ ! -d "$SQUASH_MNT" ] && \ - mkdir -m 0755 -p $SQUASH_MNT +# Mount the squash image +mount -t ramfs ramfs /squash +mkdir -p /squash/root /squash/overlay/upper /squash/overlay/work +mount -t squashfs -o ro,loop /squash-root.img /squash/root -# Mount the squashfs image -mount -t squashfs -o ro,loop $SQUASH_IMG $SQUASH_MNT +# Setup new root overlay +mkdir /newroot +mount -t overlay overlay -o lowerdir=/squash/root,upperdir=/squash/overlay/upper,workdir=/squash/overlay/work/ /newroot/ -if [ $? != 0 ]; then - echo "Unable to mount squashed initramfs image" -fi +# Move all mount points to new root to prepare chroot +mount --move /squash /newroot/squash -for file in $SQUASH_MNT/*; do - file=${file#$SQUASH_MNT/} - lowerdir=$SQUASH_MNT/$file - workdir=/squash/overlay-work/$file - upperdir=/$file - mntdir=/$file - - mkdir -m 0755 -p $workdir - mkdir -m 0755 -p $mntdir - - mount -t overlay overlay -o\ - lowerdir=$lowerdir,upperdir=$upperdir,workdir=$workdir $mntdir -done - -exec /init.orig - -echo "Something went wrong when trying to exec original init!" -exit 1 +# Jump to new root and clean setup files +SYSTEMD_IN_INITRD=lenient exec switch_root /newroot /init diff --git a/modules.d/99squash/module-setup.sh b/modules.d/99squash/module-setup.sh index 59933447..50c92c31 100644 --- a/modules.d/99squash/module-setup.sh +++ b/modules.d/99squash/module-setup.sh @@ -19,56 +19,36 @@ depends() { } installpost() { - local squash_candidate=( "usr" "etc" ) - - # shellcheck disable=SC2174 - mkdir -m 0755 -p "$squash_dir" - for folder in "${squash_candidate[@]}"; do - mv "$initdir/$folder" "$squash_dir/$folder" + # Move everything under $initdir except $squash_dir + # itself into squash image + for i in "$initdir"/*; do + [[ "$squash_dir" == "$i"/* ]] || mv "$i" "$squash_dir"/ done - # Move some files out side of the squash image, including: - # - Files required to boot and mount the squashfs image - # - Files need to be accessible without mounting the squash image - # - Initramfs marker - for file in \ - "$squash_dir"/usr/lib/dracut/* \ - "$squash_dir"/etc/initrd-release - do + # Create mount points for squash loader + mkdir -p "$initdir"/squash/ + mkdir -p "$squash_dir"/squash/ + + # Copy dracut spec files out side of the squash image + # so dracut rebuild and lsinitrd can work + for file in "$squash_dir"/usr/lib/dracut/*; do [[ -f $file ]] || continue DRACUT_RESOLVE_DEPS=1 dracutsysrootdir="$squash_dir" inst "${file#$squash_dir}" - rm "$file" done - # Install required files for the squash image setup script. - inst_multiple modprobe mount mkdir ln echo rm - - mv "$initdir"/init "$initdir"/init.orig - inst "$moddir"/init-squash.sh /init - inst "$moddir"/clear-squash.sh /squash/clear-squash.sh - - # Keep systemctl outsite if we need switch root - if [[ ! -f "$initdir/lib/dracut/no-switch-root" ]]; then - inst "systemctl" - fi - - # Remove duplicated files - for folder in "${squash_candidate[@]}"; do - find "$initdir/$folder/" -not -type d \ - -exec bash -c 'mv -f "$squash_dir${1#$initdir}" "$1"' -- "{}" \; - done - - # Install required modules for the squash image init script. + # Install required modules and binaries for the squash image init script. + DRACUT_RESOLVE_DEPS=1 inst_multiple sh mount modprobe mkdir switch_root hostonly="" instmods "loop" "squashfs" "overlay" dracut_kernel_post + + # Install squash image init script. + ln -sfn /usr/bin "$initdir/bin" + ln -sfn /usr/sbin "$initdir/sbin" + inst_simple "$moddir"/init-squash.sh /init } install() { if [[ $DRACUT_SQUASH_POST_INST ]]; then installpost - return fi - - inst "$moddir/squash-mnt-clear.service" "$systemdsystemunitdir/squash-mnt-clear.service" - $SYSTEMCTL -q --root "$initdir" add-wants initrd-switch-root.target squash-mnt-clear.service } diff --git a/modules.d/99squash/squash-mnt-clear.service b/modules.d/99squash/squash-mnt-clear.service deleted file mode 100644 index 9d94c524..00000000 --- a/modules.d/99squash/squash-mnt-clear.service +++ /dev/null @@ -1,17 +0,0 @@ -# This file is part of dracut. -# - -[Unit] -Description=Cleanup squashfs mounts when switch root -DefaultDependencies=no -Before=initrd-switch-root.service -After=initrd-switch-root.target -ConditionPathExists=/squash/root - -[Service] -Type=oneshot -RemainAfterExit=no -StandardInput=null -StandardOutput=journal+console -StandardError=journal+console -ExecStart=/squash/clear-squash.sh