cgroup: build list of all cgroups under a given cgroupfs_root

Build a list of all cgroups anchored at cgroupfs_root->allcg_list and
going through cgroup->allcg_node.  The list is protected by
cgroup_mutex and will be used to improve cgroup file handling.

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

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 5a85b3415c1b..ad2a14680b7f 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -191,6 +191,8 @@ struct cgroup {
          */
         struct list_head css_sets;
 
+        struct list_head allcg_node;    /* cgroupfs_root->allcg_list */
+
         /*
          * Linked list running through all cgroups that can
          * potentially be reaped by the release agent. Protected by