blkcg: remove blkcg->id

blkcg->id is a unique id given to each blkcg; however, the
cgroup_subsys_state which each blkcg embeds already has ->serial_nr
which can be used for the same purpose.  Drop blkcg->id and replace
its uses with blkcg->css.serial_nr.  Rename cfq_cgroup->blkcg_id to
->blkcg_serial_nr and @id in check_blkcg_changed() to @serial_nr for
consistency.

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

1 files changed, 0 insertions, 3 deletions

diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index d3fd7aa3d2a3..c567865b5f1d 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -50,9 +50,6 @@ struct blkcg {
         struct blkcg_gq                 *blkg_hint;
         struct hlist_head               blkg_list;
 
-        /* for policies to test whether associated blkcg has changed */
-        uint64_t                        id;
-
         /* TODO: per-policy storage in blkcg */
         unsigned int                    cfq_weight;     /* belongs to cfq */
         unsigned int                    cfq_leaf_weight;