linux-kernel - [PATCH 5/6] cgroup: make cgroup filesystem mounts performed by task inside isolation root see its isolation root as top cgroup

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Date:	Fri, 30 Sep 2011 13:36:24 +0200
From:	Witold Krecicki <wpk@...m.net>
To:	Paul Menage <paul@...lmenage.org>, Li Zefan <lizf@...fujitsu.com>,
	containers@...ts.linux-foundation.org
Cc:	linux-kernel@...r.kernel.org, Witold Krecicki <wpk@...m.net>
Subject: [PATCH 5/6] cgroup: make cgroup filesystem mounts performed by task inside isolation root see its isolation root as top cgroup

This patch makes all mounts of cgroup filesystems performed by task
contained in isolation root see its isolation root as top cgroup.

Signed-off-by: Witold Krecicki <wpk@...m.net>
---
 kernel/cgroup.c |   14 +++++++++++++-
 1 files changed, 13 insertions(+), 1 deletions(-)

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index c3fee33..db66a82 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1504,6 +1504,7 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
 	int ret = 0;
 	struct super_block *sb;
 	struct cgroupfs_root *new_root;
+	struct dentry *dret;
 
 	/* First find the desired set of subsystems */
 	mutex_lock(&cgroup_mutex);
@@ -1624,7 +1625,9 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
 		revert_creds(cred);
 		mutex_unlock(&cgroup_mutex);
 		mutex_unlock(&inode->i_mutex);
+		dret = sb->s_root;
 	} else {
+		struct cgroup *isol_root;
 		/*
 		 * We re-used an existing hierarchy - the new root (if
 		 * any) is not needed
@@ -1632,11 +1635,20 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
 		cgroup_drop_root(opts.new_root);
 		/* no subsys rebinding, so refcounts don't change */
 		drop_parsed_module_refcounts(opts.subsys_bits);
+		/* If root isolation is enabled give partial root */
+		cgroup_lock();
+		isol_root = cgroup_get_isolation_root(
+				task_cgroup_from_root(current, root));
+		if (isol_root)
+			dret = isol_root->dentry;
+		else
+			dret = sb->s_root;
+		cgroup_unlock();
 	}
 
 	kfree(opts.release_agent);
 	kfree(opts.name);
-	return dget(sb->s_root);
+	return dget(dret);
 
  drop_new_super:
 	deactivate_locked_super(sb);
-- 
1.7.4.1

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