[PATCH] memcg: remove redundant code in mem_cgroup_force_empty_write()

[Li Zefan <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>]

vfs guarantees the cgroup won't be destroyed, so it's redundant
to get a css reference.

Signed-off-by: Li Zefan <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
---
 mm/memcontrol.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 03c8bf7..aa3e478 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5015,15 +5015,10 @@ static int mem_cgroup_force_empty(struct mem_cgroup *memcg)
 static int mem_cgroup_force_empty_write(struct cgroup *cont, unsigned int event)
 {
 	struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
-	int ret;
 
 	if (mem_cgroup_is_root(memcg))
 		return -EINVAL;
-	css_get(&memcg->css);
-	ret = mem_cgroup_force_empty(memcg);
-	css_put(&memcg->css);
-
-	return ret;
+	return mem_cgroup_force_empty(memcg);
 }
 
 
-- 
1.8.0.2