+/**
+ * __blkg_lookup - internal version of blkg_lookup()
+ * @blkcg: blkcg of interest
+ * @q: request_queue of interest
+ * @update_hint: whether to update lookup hint with the result or not
+ *
+ * This is internal version and shouldn't be used by policy
+ * implementations. Looks up blkgs for the @blkcg - @q pair regardless of
+ * @q's bypass state. If @update_hint is %true, the caller should be
+ * holding @q->queue_lock and lookup hint is updated on success.
+ */
+static inline struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg,
+ struct request_queue *q,
+ bool update_hint)
+{
+ 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;
+
+ return blkg_lookup_slowpath(blkcg, q, update_hint);
+}
+
+/**
+ * blkg_lookup - lookup blkg for the specified blkcg - q pair
+ * @blkcg: blkcg of interest
+ * @q: request_queue of interest
+ *
+ * Lookup blkg for the @blkcg - @q pair. This function should be called
+ * under RCU read lock and is guaranteed to return %NULL if @q is bypassing
+ * - see blk_queue_bypass_start() for details.
+ */
+static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg,
+ struct request_queue *q)
+{
+ WARN_ON_ONCE(!rcu_read_lock_held());
+
+ if (unlikely(blk_queue_bypass(q)))
+ return NULL;
+ return __blkg_lookup(blkcg, q, false);
+}
+