cgroups: make unlock sequence in cgroup_get_sb consistent

Make the last unlock sequence consistent with previous unlock sequeue.
Acked-by: NBalbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: NPaul Menage <menage@google.com>
Signed-off-by: NXiaotian Feng <dfeng@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

kernel/cgroup.c

@@ -1155,8 +1155,8 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
 		BUG_ON(root->number_of_cgroups != 1);
 
 		cgroup_populate_dir(root_cgrp);
-		mutex_unlock(&inode->i_mutex);
 		mutex_unlock(&cgroup_mutex);
+		mutex_unlock(&inode->i_mutex);
 	}
 
 	simple_set_mnt(mnt, sb);