blkcg: move root blkg lookup optimization from throtl_lookup_tg() to __blkg_lookup()
Currently, both throttle and cfq policies implement their own root
blkg (blkcg_gq) lookup fast path. This patch moves root blkg
optimization from throtl_lookup_tg() to __blkg_lookup(). cfq-iosched
currently doesn't use blkg_lookup() but will be converted and drop the
optimization too.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
(cherry picked from commit 85b6bc9db6d5ab6980b43c38b5cbd11d24414ce4)
Signed-off-by: Alex Shi <alex.shi@linaro.org>
diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index 51d6bff..ab22db6 100644
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -249,6 +249,9 @@
{
struct blkcg_gq *blkg;
+ if (blkcg == &blkcg_root)
+ return q->root_blkg;
+
blkg = rcu_dereference(blkcg->blkg_hint);
if (blkg && blkg->q == q)
return blkg;