+int ll_back_merge_fn(struct request_queue *q, struct request *req,
+ struct bio *bio);
+int ll_front_merge_fn(struct request_queue *q, struct request *req,
+ struct bio *bio);
+int attempt_back_merge(struct request_queue *q, struct request *rq);
+int attempt_front_merge(struct request_queue *q, struct request *rq);
+void blk_recalc_rq_segments(struct request *rq);
+void blk_recalc_rq_sectors(struct request *rq, int nsect);
+