[Pkg-sysvinit-devel] Bug#601757: updated mountcgroupsubsys.sh

[Marcus Osdoba]

As an lxc user, I like a semi-automatic (distributional way) of setting 
up the needed cgroup-subsystems.
Ubuntu uses a lightweight variant of cgroups-bin (currently blocked in 
wheezy).

As always you may have more than one way to achive a proper cgroup handling.
Attached is my (updated) solution which is an initscript in parallel to 
such as mountdevsubfs.sh and similar.

I use this on Squeeze-server running with latest lxc-7.5.x from Wheezy.
It was never tested together with systemd. All subsystems are mounted in 
their own subdirectories.

Feel free to examine the functionality and reuse it in initscripts for 
future cgroup handling in wheezy.
-------------- next part --------------
#! /bin/sh
### BEGIN INIT INFO
# Provides:          mountcgroupsubsys
# Required-Start:    mountkernfs
# Required-Stop:
# Should-Start:      
# Default-Start:     S
# Default-Stop:
# Short-Description: Mount cgroup subsystems
# Description:       Mounts every cgroup subsystem
#                    in it's own directory under /sys/fs/cgroup
### END INIT INFO

PATH=/sbin:/bin
. /lib/init/vars.sh

. /lib/lsb/init-functions
. /lib/init/mount-functions.sh

[ -f /etc/default/tmpfs ] && . /etc/default/tmpfs

CGROUP_MOUNTTAB=/proc/mounts # /etc/mtab does not show cgroup subsystems after stop/start
export CGROUP_MOUNTTAB

do_start () {
	#
	# Mount cgroup on /sys/fs/cgroup
	#
	# Only mount cgroup if it is supported and enabled in /etc/default/tmpfs
	if grep -E -qs "cgroup\$" /proc/filesystems && [ -d /sys/fs/cgroup ] && [ yes = "$CGROUPSUBSYSTEMS" ]
	then
		RW_OPT=
		[ "${RW_SIZE:=$TMPFS_SIZE}" ] && RW_OPT=",size=$RW_SIZE"
		domount tmpfs "" /sys/fs/cgroup tmpfs -omode=0755,nosuid$RW_OPT
		CGROUP_EXCL_SUBSYS=${CGROUP_EXCL_SUBSYS:-"ns"} # ns (namespace) subsystem marked as deprecated
		grep -v "^#" /proc/cgroups | while read subsysline; do
			subsys=$(echo $subsysline | /usr/bin/awk '{print $1}' )
			subsys_enabled=$(echo $subsysline | /usr/bin/awk '{print $4}' )
			if [ ! -d /sys/fs/cgroup/${subsys} -a "$subsys_enabled" = "1" ]
			then
				mkdir /sys/fs/cgroup/${subsys}
				domount cgroup "" /sys/fs/cgroup/${subsys} cgroup -o${subsys}
				[ $? -eq 0 ] && log_success_msg "Successfully mounted /sys/fs/cgroup/${subsys}."
			else
				log_warning_msg "Directory /sys/fs/cgroup/${subsys} does already exists or subsystem is not enabled. Do not try to mount cgroup subsystem named $subsys."
			fi
		done
	else
		log_warning_msg "Cgroups not supported by kernel or CGROUPSUBSYSTEMS not set to 'yes' in /etc/default/tmpfs."
	fi


}

do_stop () {
	if [ -d /sys/fs/cgroup ]
	then
		for subsys in $(/usr/bin/awk '{print $1}' /proc/cgroups); do
			if [ -d /sys/fs/cgroup/${subsys} ]
			then
				umount /sys/fs/cgroup/${subsys}
				[ $? -ne 0 ] && log_warning_msg "Could not unmount /sys/fs/cgroup/${subsys}."
				rmdir /sys/fs/cgroup/${subsys}
				[ $? -eq 0 ] && log_success_msg "Successfully removed /sys/fs/cgroup/${subsys}."
			fi
		done
		grep "/sys/fs/cgroup" $CGROUP_MOUNTTAB > /dev/null 
		if [ $? -eq 0 ]
		then
			umount /sys/fs/cgroup
			[ $? -eq 0 ] && log_success_msg "Successfully unmounted /sys/fs/cgroup."
		fi
	else
		log_warning_msg "Directory /sys/fs/cgroup not found. Do not try to unmount cgroup subsystems."
	fi
}

do_status () {
	grep "/sys/fs/cgroup" $CGROUP_MOUNTTAB > /dev/null
	if [ -d /sys/fs/cgroup -a $? -eq 0 ]
        then
		for subsys in $(/usr/bin/awk '{print $1}' /proc/cgroups); do
			if [ -d /sys/fs/cgroup/${subsys} ]
			then
				log_action_msg "Cgroup subsystem ${subsys} found in /sys/fs/cgroup/${subsys}"
			fi
		done
	else
		log_action_msg "Did not find mounted /sys/fs/cgroup"
	fi
}

case "$1" in
  "")
	echo "Warning: mountcgroupsubsys should be called with the 'start' argument." >&2
	do_start
	;;
  start)
	do_start
	;;
  status)
	do_status
	;;
  restart|reload|force-reload)
	echo "Error: argument '$1' not supported" >&2
	exit 3
	;;
  stop)
	do_stop
	;;
  *)
	echo "Usage: mountcgroupsubsys [start|stop]" >&2
	exit 3
	;;
esac