block: move the initial blkg lookup into blkg_tryget_closest (13c7863d) · Commits · 戴 / test

block/blk-cgroup.c

+14 −19

Original line number	Diff line number	Diff line
		@@ -1716,19 +1716,20 @@ void blkcg_add_delay(struct blkcg_gq *blkg, u64 now, u64 delta)

		/**
		* blkg_tryget_closest - try and get a blkg ref on the closet blkg
		* @blkg: blkg to get
		* @bio: target bio
		* @css: target css
		*
		* This needs to be called rcu protected. As the failure mode here is to walk
		* up the blkg tree, this ensure that the blkg->parent pointers are always
		* valid. This returns the blkg that it ended up taking a reference on or %NULL
		* if no reference was taken.
		* As the failure mode here is to walk up the blkg tree, this ensure that the
		* blkg->parent pointers are always valid. This returns the blkg that it ended
		* up taking a reference on or %NULL if no reference was taken.
		*/
		static inline struct blkcg_gq blkg_tryget_closest(struct blkcg_gq blkg)
		static inline struct blkcg_gq blkg_tryget_closest(struct bio bio,
		struct cgroup_subsys_state *css)
		{
		struct blkcg_gq *ret_blkg = NULL;

		WARN_ON_ONCE(!rcu_read_lock_held());
		struct blkcg_gq blkg, ret_blkg = NULL;

		rcu_read_lock();
		blkg = blkg_lookup_create(css_to_blkcg(css), bio->bi_disk->queue);
		while (blkg) {
		if (blkg_tryget(blkg)) {
		ret_blkg = blkg;
		@@ -1736,6 +1737,7 @@ static inline struct blkcg_gq blkg_tryget_closest(struct blkcg_gq blkg)
		}
		blkg = blkg->parent;
		}
		rcu_read_unlock();

		return ret_blkg;
		}
		@@ -1757,21 +1759,14 @@ static inline struct blkcg_gq blkg_tryget_closest(struct blkcg_gq blkg)
		void bio_associate_blkg_from_css(struct bio *bio,
		struct cgroup_subsys_state *css)
		{
		struct request_queue *q = bio->bi_disk->queue;

		if (bio->bi_blkg)
		blkg_put(bio->bi_blkg);

		if (css && css->parent) {
		struct blkcg_gq *blkg;

		rcu_read_lock();
		blkg = blkg_lookup_create(css_to_blkcg(css), q);
		bio->bi_blkg = blkg_tryget_closest(blkg);
		rcu_read_unlock();
		bio->bi_blkg = blkg_tryget_closest(bio, css);
		} else {
		blkg_get(q->root_blkg);
		bio->bi_blkg = q->root_blkg;
		blkg_get(bio->bi_disk->queue->root_blkg);
		bio->bi_blkg = bio->bi_disk->queue->root_blkg;
		}
		}
		EXPORT_SYMBOL_GPL(bio_associate_blkg_from_css);

Admin message