blkio: Take care of cgroup deletion and cfq group reference counting

o One can choose to change elevator or delete a cgroup. Implement group
  reference counting so that both elevator exit and cgroup deletion can
  take place gracefully.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Nauman Rafique <nauman@google.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index ba5703f69b42..cd50a2f8733e 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -26,6 +26,7 @@ struct blkio_group {
         /* An rcu protected unique identifier for the group */
         void *key;
         struct hlist_node blkcg_node;
+        unsigned short blkcg_id;
 };
 
 #define BLKIO_WEIGHT_MIN        100