[arch-projects] [PATCH] shutdown: add a shutdown hook

[Dan McGee]

On Fri, Jul 22, 2011 at 7:13 PM, Tom Gundersen <teg at jklm.no> wrote:
> Enabling the shutdown hook and using systemd v31
> (which is yet to be released), means that on shutdown the root
> will be pivoted to /run/initramfs, from where the rootfs and
> all its submonuts (such as /usr) are unmounted cleanly.
>
> The same functionality will be supported in a future release of
> initscript.
>
> A natural next step is to add an "/usr"-hook, which mounts the /usr
> partition (if it exists) in the initramfs, so initscripts (and systemd)
> can always rely on it being mounted, and we no longer need to move some
> binaries/libraries to /bin, /sbin and /lib (as this does not work well
> at the moment).
>
> One might argue that this functionality does not beling in mkinitrd.
> The reason I propose it for inclusion here is:
> - it is independent of initscripts, so does not really belong there either.
> - in the future one might imagine extending this to integrate more tightly
>  with the rest of the initramfs (e.g. store state/logs in /run/initramfs
>  to ease debugging, or add shutdown-hooks, to go with the boot-hooks, to
>  gracefully tear down things such as dm or nfs mounts at shutdown).
> - by behaving like dracut, integrating with systemd became trivial, and IMHO
>  there is no point in systemd/initscripts/dracut/mkinitrd differing at the
>  interface level.
>
> v2: copy the needed libraries to the new ramfs
> v3: support for 32-bit, and cleanup
If you put these below the --- (three dashes), they won't show up when
you commit to git. (Use git format-patch then edit the results before
send-email).

>
> Signed-off-by: Tom Gundersen <teg at jklm.no>
> ---
>  Makefile         |    1 +
>  hooks/shutdown   |   17 +++++++++++++++++
>  install/shutdown |   16 ++++++++++++++++
>  shutdown         |   12 ++++++++++++
>  4 files changed, 46 insertions(+), 0 deletions(-)
>  create mode 100644 hooks/shutdown
>  create mode 100644 install/shutdown
>  create mode 100644 shutdown
>
> diff --git a/Makefile b/Makefile
> index 18df47f..d4bb4e1 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -35,6 +35,7 @@ install: all
>        chmod 755 ${DESTDIR}/bin/lsinitcpio ${DESTDIR}/sbin/mkinitcpio
>
>        install -m644 mkinitcpio.conf ${DESTDIR}/etc/mkinitcpio.conf
> +       install -m755 -t ${DESTDIR}/lib/initcpio/shutdown shutdown
>        install -m755 -t ${DESTDIR}/lib/initcpio init
>        install -m644 -t ${DESTDIR}/lib/initcpio init_functions functions
>        install -m644 01-memdisk.rules ${DESTDIR}/lib/initcpio/udev/01-memdisk.rules
> diff --git a/hooks/shutdown b/hooks/shutdown
> new file mode 100644
> index 0000000..f22a0f0
> --- /dev/null
> +++ b/hooks/shutdown
> @@ -0,0 +1,17 @@
> +# vim: set ft=sh:
> +run_hook ()
> +{
> +    msg -n ":: Creating shutdown ramfs..."
> +    mkdir -p /run/initramfs/usr/bin
> +    mkdir /run/initramfs/usr/sbin
> +    mkdir /run/initramfs/bin
> +    mkdir /run/initramfs/sbin
> +    mkdir /run/initramfs/lib
One liner:
mkdir -p /run/initramfs/{usr/bin,usr/sbin,bin,sbin,lib}

> +    cp /bin/busybox /run/initramfs/bin/
> +    cp /lib/ld-* /run/initramfs/lib/
> +    cp /lib/libc.* /run/initramfs/lib/
> +
> +    chroot /run/initramfs /bin/busybox --install
> +    cp /shutdown /run/initramfs/
> +    msg "done."
> +}
> diff --git a/install/shutdown b/install/shutdown
> new file mode 100644
> index 0000000..019a6a5
> --- /dev/null
> +++ b/install/shutdown
> @@ -0,0 +1,16 @@
> +#!/bin/bash
> +
> +build() {
> +    SCRIPT="shutdown"
> +    add_binary /lib/initcpio/shutdown /shutdown
> +}
> +
> +help () {
> +    cat <<HELPEOF
> +This hook will create a shutdown initrd in /run/mkinitramfs
> +that we can pivot to on shutdown in order to unmount /
> +(and any submounts such as /usr) cleanly.
> +HELPEOF
> +}
> +
> +# vim: set ft=sh ts=4 sw=4 et:
> diff --git a/shutdown b/shutdown
> new file mode 100644
> index 0000000..db2d394
> --- /dev/null
> +++ b/shutdown
> @@ -0,0 +1,12 @@
> +#!/bin/sh
> +# shutdown
> +
> +# unmount everything that was mounted on the old root
> +umount `mount | awk '{ print $3 }' | grep "^/oldroot" | sort -r`
> +
> +# reboot / poweroff / halt, depending on the argument passed by init
> +# if something invalid is passed, we halt
> +case "$1" in
> +  reboot|poweroff|halt) "$1" -f ;;
> +  *) halt -f;;
> +esac
> --
> 1.7.6