cgroup: fix to allow mounting a hierarchy by name

If we mount a hierarchy with a specified name, the name is unique,
and we can use it to mount the hierarchy without specifying its
set of subsystem names. This feature is documented is
Documentation/cgroups/cgroups.txt section 2.3

Here's an example:

	# mount -t cgroup -o cpuset,name=myhier xxx /cgroup1
	# mount -t cgroup -o name=myhier xxx /cgroup2

But it was broken by commit 32a8cf235e2f192eb002755076994525cdbaa35a
(cgroup: make the mount options parsing more accurate)

This fixes the regression.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index bab5c17..39c7cae 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1193,10 +1193,10 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
 
        /*
         * If the 'all' option was specified select all the subsystems,
-        * otherwise 'all, 'none' and a subsystem name options were not
-        * specified, let's default to 'all'
+        * otherwise if 'none', 'name=' and a subsystem name options
+        * were not specified, let's default to 'all'
         */
-       if (all_ss || (!all_ss && !one_ss && !opts->none)) {
+       if (all_ss || (!one_ss && !opts->none && !opts->name)) {
                for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
                        struct cgroup_subsys *ss = subsys[i];
                        if (ss == NULL)