blkcg: add request_queue->root_blkg
With per-queue policy activation, root blkg creation will be moved to
blkcg core. Add q->root_blkg in preparation. For blk-throtl, this
replaces throtl_data->root_tg; however, cfq needs to keep
cfqd->root_group for !CONFIG_CFQ_GROUP_IOSCHED.
This is to prepare for per-queue policy activation and doesn't cause
any functional difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index d2c69f8..b01c377 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -31,6 +31,7 @@
struct request;
struct sg_io_hdr;
struct bsg_job;
+struct blkio_group;
#define BLKDEV_MIN_RQ 4
#define BLKDEV_MAX_RQ 128 /* Default maximum */
@@ -369,6 +370,7 @@
struct list_head icq_list;
#ifdef CONFIG_BLK_CGROUP
+ struct blkio_group *root_blkg;
struct list_head blkg_list;
#endif