cgroups: refactor cgroups

add a deprecation warning for cgroups v1, and rework rc-cgroups.sh into
cgroups.sh with an api focused on cgroups v2

move into a new layout with a supervision root cgroup as /rc, services
will then go in /rc/$RC_SVCNAME, and compatibility with the old
/openrc.$RC_SVCNAME is kept though restarting a service will use the new
layout

this also fixes a bug where cgroup_cleanup would not ever trigger due to
a bug in cgroup_running

Author: navi-desu

init.d/cgroups.in

@@ -21,6 +21,7 @@ depend()
 
 cgroup1_base()
 {
+	eerror "cgroups v1 is deprecated. Please unset rc_cgroup_mode."
 	grep -qw cgroup /proc/filesystems || return 0
 	if ! mountinfo -q /sys/fs/cgroup; then
 		ebegin "Mounting cgroup filesystem"
@@ -44,63 +45,65 @@ cgroup1_controllers()
 {
 	yesno "${rc_controller_cgroups:-YES}" && [ -e /proc/cgroups ]  &&
 	grep -qw cgroup /proc/filesystems || return 0
+
 	while read -r name _ _ enabled _; do
-		case "${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}"
-				yesno "${rc_cgroup_memory_use_hierarchy:-no}" &&
-					[ "${name}" = memory ] &&
-					echo 1 > /sys/fs/cgroup/memory/memory.use_hierarchy
-				;;
-		esac
+		[ "$enabled" = 1 ] || continue;
+		mountinfo -q "/sys/fs/cgroup/${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}"
+		if [ yesno "${rc_cgroup_memory_use_hierarchy:-no}" && [ "${name}" = memory ]; then
+			echo 1 > /sys/fs/cgroup/memory/memory.use_hierarchy
+		fi
 	done < /proc/cgroups
 	return 0
 }
 
 cgroup2_base()
 {
 	grep -qw cgroup2 /proc/filesystems || return 0
-	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
+
+	mkdir -p "${cgroup_root}"
+	mount -t cgroup2 none -o "${cgroup_opts},nsdelegate" "${cgroup_root}" 2> /dev/null ||
+		mount -t cgroup2 none -o "${cgroup_opts}" "${cgroup_root}"
+	mkdir -p "${cgroup_root}/rc"
 }
 
-cgroup2_controllers()
+setup_controller()
 {
-	grep -qw cgroup2 /proc/filesystems || return 0
-	local active cgroup_path x y
-	cgroup_path="$(cgroup2_find_path)"
-	[ -z "${cgroup_path}" ] && return 0
-	[ ! -e "${cgroup_path}/cgroup.controllers" ] && return 0
-	[ ! -e "${cgroup_path}/cgroup.subtree_control" ]&& return 0
-	read -r active < "${cgroup_path}/cgroup.controllers"
-	for x in ${active}; do
-	case "${rc_cgroup_mode:-unified}" in
-		unified)
-			echo "+${x}"  > "${cgroup_path}/cgroup.subtree_control"
-			;;
+	local root="$1" controller allowed
+	shift
+
+	[ ! -e "${root}/cgroup.controllers" ] && return 0
+	[ ! -e "${root}/cgroup.subtree_control" ] && return 0
+
+	for controller; do
+		case "${rc_cgroup_mode:-unified}" in
+		unified) echo "+${controller}" > "${root}/cgroup.subtree_control" ;;
 		hybrid)
-			for y in ${rc_cgroup_controllers}; do
-				if [ "$x" = "$y" ]; then
-					echo "+${x}"  > "${cgroup_path}/cgroup.subtree_control"
+			for allowed in ${rc_cgroup_controllers}; do
+				if [ "$controller" = "$allowed" ]; then
+					echo "+${controller}" > "${root}/cgroup.subtree_control"
 				fi
 			done
 			;;
 		esac
 	done
-	return 0
+}
+
+cgroup2_controllers()
+{
+	grep -qw cgroup2 /proc/filesystems || return 0
+	local active
+	read -r active < "${cgroup_root}/cgroup.controllers"
+	setup_controller "${cgroup_root}" $active
+	setup_controller "${cgroup_root}/rc" $active
 }
 
 cgroups_hybrid()
@@ -109,21 +112,18 @@ cgroups_hybrid()
 	cgroup2_base
 	cgroup2_controllers
 	cgroup1_controllers
-	return 0
 }
 
 cgroups_legacy()
 {
 	cgroup1_base
 	cgroup1_controllers
-	return 0
 }
 
 cgroups_unified()
 {
 	cgroup2_base
 	cgroup2_controllers
-	return 0
 }
 
 mount_cgroups()
@@ -133,7 +133,6 @@ mount_cgroups()
 	legacy) cgroups_legacy ;;
 	unified) cgroups_unified ;;
 	esac
-	return 0
 }
 
 restorecon_cgroups()
@@ -143,7 +142,6 @@ restorecon_cgroups()
 		restorecon -rF /sys/fs/cgroup >/dev/null 2>&1
 		eend $?
 	fi
-	return 0
 }
 
 start()
@@ -153,5 +151,6 @@ start()
 		mount_cgroups
 		restorecon_cgroups
 	fi
+
 	return 0
 }