split cgroups mounting out of sysfs

This is neceessary to allow cgroups to be mounted in an lxc/lxd
container.

Fixes https://github.com/openrc/openrc/issues/187

NEWS.md

@@ -5,6 +5,23 @@ the information in this file is in reverse order.
 
 ## OpenRC 0.35
 
+In this version, the cgroups mounting logic has been moved from the
+sysfs service to the cgroups service. This was done so cgroups can be
+mounted inside an lxc/lxd container without using the other parts of the
+sysfs service.
+
+?As a result of this change, if you are upgrading, you need to add
+cgroups to your sysinit runlevel by running the following command as
+root:
+
+```
+# rc-update add cgroups sysinit
+```
+
+For more information, see the following issue:
+
+https://github.com/openrc/openrc/issues/187
+
 Consider this your second notification with regard to /etc/mtab being a
 file instead of a symbolic link.
 

init.d/.gitignore

@@ -1,5 +1,6 @@
 agetty
 binfmt
+cgroups
 modules-load
 bootmisc
 fsck

init.d/Makefile

@@ -21,9 +21,10 @@ SRCS-FreeBSD=	hostid.in modules.in moused.in newsyslog.in pf.in rarpd.in \
 SRCS-FreeBSD+=	adjkerntz.in devd.in dumpon.in encswap.in ipfw.in \
 		modules-load.in mixer.in nscd.in powerd.in syscons.in
 
-SRCS-Linux=	agetty.in binfmt.in devfs.in dmesg.in hwclock.in consolefont.in \
-	keymaps.in killprocs.in modules.in modules-load.in mount-ro.in mtab.in \
-	numlock.in procfs.in net-online.in sysfs.in termencoding.in
+SRCS-Linux=	agetty.in binfmt.in devfs.in cgroups.in dmesg.in hwclock.in \
+	consolefont.in keymaps.in killprocs.in modules.in modules-load.in \
+	mount-ro.in mtab.in numlock.in procfs.in net-online.in sysfs.in \
+termencoding.in
 
 # Generic BSD scripts
 SRCS-NetBSD=	hostid.in moused.in newsyslog.in pf.in rarpd.in rc-enabled.in \

init.d/cgroups.in

@@ -0,0 +1,147 @@
+#!@SBINDIR@/openrc-run
+# Copyright (c) 2017 The OpenRC Authors.
+# See the Authors file at the top-level directory of this distribution and
+# https://github.com/OpenRC/openrc/blob/master/AUTHORS
+#
+# This file is part of OpenRC. It is subject to the license terms in
+# the LICENSE file found in the top-level directory of this
+# distribution and at https://github.com/OpenRC/openrc/blob/master/LICENSE
+# This file may not be copied, modified, propagated, or distributed
+# except according to the terms contained in the LICENSE file.
+
+description="Mount the control groups."
+
+cgroup_opts=nodev,noexec,nosuid
+
+depend()
+{
+	keyword -docker -prefix -systemd-nspawn -vserver
+	after sysfs
+}
+
+cgroup1_base()
+{
+	grep -qw cgroup /proc/filesystems || return 0
+	if ! mountinfo -q /sys/fs/cgroup; then
+		ebegin "Mounting cgroup filesystem"
+		local opts="${cgroup_opts},mode=755,size=${rc_cgroupsize:-10m}"
+		mount -n -t tmpfs -o "${opts}" cgroup_root /sys/fs/cgroup
+		eend $?
+	fi
+
+	if ! mountinfo -q /sys/fs/cgroup/openrc; then
+		local agent="${RC_LIBEXECDIR}/sh/cgroup-release-agent.sh"
+		mkdir /sys/fs/cgroup/openrc
+		mount -n -t cgroup \
+			-o none,${cgroup_opts},name=openrc,release_agent="$agent" \
+			openrc /sys/fs/cgroup/openrc
+		printf 1 > /sys/fs/cgroup/openrc/notify_on_release
+	fi
+	return 0
+}
+
+cgroup1_controllers()
+{
+	yesno "${rc_controller_cgroups:-YES}" && [ -e /proc/cgroups ] || return 0
+	while read -r name _ _ enabled _; do
+		case "${enabled}" in
+			1)	mountinfo -q "/sys/fs/cgroup/${name}" && continue
+				local x
+				for x in $rc_cgroup_controllers; do
+				[ "${name}" = "blkio" ] && [ "${x}" = "io" ] &&
+					continue 2
+				[ "${name}" = "${x}" ] &&
+				continue 2
+				done
+				mkdir "/sys/fs/cgroup/${name}"
+				mount -n -t cgroup -o "${cgroup_opts},${name}" \
+					"${name}" "/sys/fs/cgroup/${name}"
+				;;
+		esac
+	done < /proc/cgroups
+	return 0
+}
+
+cgroup2_base()
+{
+	local base
+	base="$(cgroup2_find_path)"
+	mkdir -p "${base}"
+	mount -t cgroup2 none -o "${cgroup_opts},nsdelegate" "${base}" 2> /dev/null ||
+		mount -t cgroup2 none -o "${cgroup_opts}" "${base}"
+	return 0
+}
+
+cgroup2_controllers()
+{
+	local active cgroup_path x y
+	cgroup_path="$(cgroup2_find_path)"
+	[ -z "${cgroup_path}" ] && return 0
+	[ -e "${cgroup_path}/cgroup.controllers" ] &&
+	read -r active < "${cgroup_path}/cgroup.controllers"
+	for x in ${rc_cgroup_controllers}; do
+		for y in ${active}; do
+		[ "$x" = "$y" ] &&
+			[ -e "${cgroup_path}/cgroup.subtree_control" ]&&
+			echo "+${x}"  > "${cgroup_path}/cgroup.subtree_control"
+		done
+	done
+	return 0
+}
+
+cgroups_hybrid()
+{
+	grep -qw cgroup /proc/filesystems || return 0
+	cgroup1_base
+	if grep -qw cgroup2 /proc/filesystems; then
+		cgroup2_base
+		cgroup2_controllers
+	fi
+	cgroup1_controllers
+	return 0
+}
+
+cgroups_legacy()
+{
+	grep -qw cgroup /proc/filesystems || return 0
+	cgroup1_base
+	cgroup1_controllers
+	return 0
+}
+
+cgroups_unified()
+{
+	cgroup2_base
+	cgroup2_controllers
+	return 0
+}
+
+mount_cgroups()
+{
+	case "${rc_cgroup_mode:-hybrid}" in
+	hybrid) cgroups_hybrid ;;
+	legacy) cgroups_legacy ;;
+	unified) cgroups_unified ;;
+	esac
+	return 0
+}
+
+restorecon_cgroups()
+{
+	if [ -x /sbin/restorecon ]; then
+		ebegin "Restoring SELinux contexts in /sys/fs/cgroup"
+		restorecon -rF /sys/fs/cgroup >/dev/null 2>&1
+		eend $?
+	fi
+	return 0
+}
+
+start()
+{
+	# set up kernel support for cgroups
+	if [ -d /sys/fs/cgroup ]; then
+		mount_cgroups
+		restorecon_cgroups
+	fi
+	return 0
+}

init.d/sysfs.in

@@ -107,122 +107,11 @@ mount_misc()
 	fi
 }
 
-cgroup1_base()
-{
-	grep -qw cgroup /proc/filesystems || return 0
-	if ! mountinfo -q /sys/fs/cgroup; then
-		ebegin "Mounting cgroup filesystem"
-		local opts="${sysfs_opts},mode=755,size=${rc_cgroupsize:-10m}"
-		mount -n -t tmpfs -o "${opts}" cgroup_root /sys/fs/cgroup
-		eend $?
-	fi
-
-	if ! mountinfo -q /sys/fs/cgroup/openrc; then
-		local agent="${RC_LIBEXECDIR}/sh/cgroup-release-agent.sh"
-		mkdir /sys/fs/cgroup/openrc
-		mount -n -t cgroup \
-			-o none,${sysfs_opts},name=openrc,release_agent="$agent" \
-			openrc /sys/fs/cgroup/openrc
-		printf 1 > /sys/fs/cgroup/openrc/notify_on_release
-	fi
-	return 0
-}
-
-cgroup1_controllers()
-{
-	yesno "${rc_controller_cgroups:-YES}" && [ -e /proc/cgroups ] || return 0
-	while read -r name _ _ enabled rest; do
-		case "${enabled}" in
-			1)	mountinfo -q "/sys/fs/cgroup/${name}" && continue
-				local x
-				for x in $rc_cgroup_controllers; do
-				[ "${name}" = "blkio" ] && [ "${x}" = "io" ] &&
-					continue 2
-				[ "${name}" = "${x}" ] &&
-				continue 2
-				done
-				mkdir "/sys/fs/cgroup/${name}"
-				mount -n -t cgroup -o "${sysfs_opts},${name}" \
-					"${name}" "/sys/fs/cgroup/${name}"
-				;;
-		esac
-	done < /proc/cgroups
-	return 0
-}
-
-cgroup2_base()
-{
-	local base
-	base="$(cgroup2_find_path)"
-	mkdir -p "${base}"
-	mount -t cgroup2 none -o "${sysfs_opts},nsdelegate" "${base}" 2> /dev/null ||
-		mount -t cgroup2 none -o "${sysfs_opts}" "${base}"
-	return 0
-}
-
-cgroup2_controllers()
-{
-	local active cgroup_path x y
-	cgroup_path="$(cgroup2_find_path)"
-	[ -z "${cgroup_path}" ] && return 0
-	[ -e "${cgroup_path}/cgroup.controllers" ] &&
-	read -r active < "${cgroup_path}/cgroup.controllers"
-	for x in ${rc_cgroup_controllers}; do
-		for y in ${active}; do
-		[ "$x" = "$y" ] &&
-			[ -e "${cgroup_path}/cgroup.subtree_control" ]&&
-			echo "+${x}"  > "${cgroup_path}/cgroup.subtree_control"
-		done
-	done
-	return 0
-}
-
-cgroups_hybrid()
-{
-	grep -qw cgroup /proc/filesystems || return 0
-	cgroup1_base
-	if grep -qw cgroup2 /proc/filesystems; then
-		cgroup2_base
-		cgroup2_controllers
-	fi
-	cgroup1_controllers
-	return 0
-}
-
-cgroups_legacy()
-{
-	grep -qw cgroup /proc/filesystems || return 0
-	cgroup1_base
-	cgroup1_controllers
-	return 0
-}
-
-cgroups_unified()
-{
-	cgroup2_base
-	cgroup2_controllers
-	return 0
-}
-
-mount_cgroups()
-{
-	# set up kernel support for cgroups
-	if [ -d /sys/fs/cgroup ]; then
-		case "${rc_cgroup_mode:-hybrid}" in
-		hybrid) cgroups_hybrid ;;
-		legacy) cgroups_legacy ;;
-		unified) cgroups_unified ;;
-		esac
-	fi
-	return 0
-}
-
 restorecon_sys()
 {
 	if [ -x /sbin/restorecon ]; then
 		ebegin "Restoring SELinux contexts in /sys"
 		restorecon -F /sys/devices/system/cpu/online >/dev/null 2>&1
-		restorecon -rF /sys/fs/cgroup >/dev/null 2>&1
 		eend $?
 	fi
 }
@@ -231,7 +120,6 @@ start()
 {
 	mount_sys
 	mount_misc
-	mount_cgroups
 	restorecon_sys
 	return 0
 }

runlevels/Makefile

@@ -38,7 +38,7 @@ BOOT-FreeBSD+=	adjkerntz dumpon syscons
 
 BOOT-Linux+=	binfmt hwclock keymaps modules mtab procfs termencoding
 SHUTDOWN-Linux=	killprocs mount-ro
-SYSINIT-Linux=	devfs dmesg sysfs
+SYSINIT-Linux=	devfs cgroups dmesg sysfs
 
 # Generic BSD stuff
 BOOT-NetBSD+=	hostid newsyslog savecore syslogd