[20/42] cgroup: fix to allow mounting a hierarchy by name

3.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Li Zefan <redacted>

commit 0d19ea866562e46989412a0676412fa0983c9ce7 upstream.

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 <redacted>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 kernel/cgroup.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c

@@ -1175,10 +1175,10 @@ static int parse_cgroupfs_options(char *
 
 	/*
 	 * 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)