[PATCH] cgroup mount: ignore nsroot=

As of the patch "cgroup namespaces: add a 'nsroot=' mountinfo field", 
cgroupfs mountinfo output shows 'nsroot='.  If userspace like criu
copy/pastes mount options from there into a new mount command, we should
ignore it.

Signed-off-by: Serge Hallyn <serge.hallyn-GeWIH/nMZzLQT0dZR+AlfA@public.gmane.org>
---
 kernel/cgroup.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index ef0c25d..69fb112 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c

@@ -1680,6 +1680,10 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
 			opts->none = true;
 			continue;
 		}
+		if (!strncmp(token, "nsroot=", 7)) {
+			/* ignore nsroot= copied from mountinfo */
+			continue;
+		}
 		if (!strcmp(token, "all")) {
 			/* Mutually exclusive option 'all' + subsystem name */
 			if (one_ss)

-- 
2.7.0