blkcg: add blkg_policy_data->plid

Add pd->plid so that the policy a pd belongs to can be identified
easily.  This will be used to implement hierarchical blkg_[rw]stats.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index 24462258200e..40f5b9768aac 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -81,8 +81,9 @@ struct blkg_rwstat {
  * beginning and pd_size can't be smaller than pd.
  */
 struct blkg_policy_data {
-        /* the blkg this per-policy data belongs to */
+        /* the blkg and policy id this per-policy data belongs to */
         struct blkcg_gq                 *blkg;
+        int                             plid;
 
         /* used during policy activation */
         struct list_head                alloc_node;