#!/bin/sh
# Tries to work around LP bug #696454, i.e. that if the root /dev/nbd0 device
# is unmounted on shutdown then nbd read errors occur, and if it isn't, then
# the nbd-server process on the server doesn't terminate.
# Called by init scripts on reboot or shutdown.

case "$RUNLEVEL" in
    0)
        key="o"
        message="Shutting down NOW."
        ;;
    6)
        key="b"
        message="Rebooting NOW."
        ;;
    *)
        echo "nbd-disconnect should only be called by initscripts on reboot/shutdown." >&2
        exit 1
        ;;
esac

disconnect() {
    echo "$message" >&2
    nbd-client -d /dev/nbd0
    echo $key > /proc/sysrq-trigger
}

# Disconnect swap nbd devices first
while read device etc; do
    case "$device" in
        /dev/nbd[1-9])
            swapoff "$device"
            nbd-client -d "$device"
            ;;
    esac
done < /proc/swaps

# If we're not using an nbd root, exit
grep -qw "nbdroot" /proc/cmdline || exit 0

trap "disconnect" 0 HUP INT QUIT KILL SEGV PIPE TERM
sync
# Give up to 5 seconds for other services to be called.
# If they finish before that time, process termination will start, and the trap
# will be called.
sleep 5