From c3827fb6d1d80856ca9107758e07ba677bc0d43b Mon Sep 17 00:00:00 2001
From: Waiman Long <longman@redhat.com>
Date: Thu, 17 Aug 2017 15:33:09 -0400
Subject: [PATCH 5/7] cgroup: Add mount flag to enable cpuset to use v2
 behavior in v1 cgroup
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A new mount option "cpuset_v2_mode" is added to the v1 cgroupfs
filesystem to enable cpuset controller to use v2 behavior in a v1
cgroup. This mount option applies only to cpuset controller and have
no effect on other controllers.

Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
(cherry-picked from e1cba4b85daa71b710384d451ff6238d5e4d1ff6)
Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
---
 include/linux/cgroup-defs.h | 5 +++++
 kernel/cgroup/cgroup-v1.c   | 6 ++++++
 2 files changed, 11 insertions(+)

diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
index 09f4c7df1478..c344e77707a5 100644
--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -74,6 +74,11 @@ enum {
 	 * aren't writeable from inside the namespace.
 	 */
 	CGRP_ROOT_NS_DELEGATE	= (1 << 3),
+
+	/*
+	 * Enable cpuset controller in v1 cgroup to use v2 behavior.
+	 */
+	CGRP_ROOT_CPUSET_V2_MODE = (1 << 4),
 };
 
 /* cftype->flags */
diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
index 7bf4b1533f34..ce7426b875f5 100644
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -846,6 +846,8 @@ static int cgroup1_show_options(struct seq_file *seq, struct kernfs_root *kf_roo
 		seq_puts(seq, ",noprefix");
 	if (root->flags & CGRP_ROOT_XATTR)
 		seq_puts(seq, ",xattr");
+	if (root->flags & CGRP_ROOT_CPUSET_V2_MODE)
+		seq_puts(seq, ",cpuset_v2_mode");
 
 	spin_lock(&release_agent_path_lock);
 	if (strlen(root->release_agent_path))
@@ -900,6 +902,10 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
 			opts->cpuset_clone_children = true;
 			continue;
 		}
+		if (!strcmp(token, "cpuset_v2_mode")) {
+			opts->flags |= CGRP_ROOT_CPUSET_V2_MODE;
+			continue;
+		}
 		if (!strcmp(token, "xattr")) {
 			opts->flags |= CGRP_ROOT_XATTR;
 			continue;
-- 
2.14.2

