block: don't check ->rq_disk in merges

There is a 1:1 relationship between request_queues and gendisks now, so
no need for these extra checks.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20211126121802.2090656-3-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-merge.c

@@ -777,8 +777,7 @@ static struct request *attempt_merge(struct request_queue *q,
 	if (req_op(req) != req_op(next))
 		return NULL;
 
-	if (rq_data_dir(req) != rq_data_dir(next)
-	    || req->rq_disk != next->rq_disk)
+	if (rq_data_dir(req) != rq_data_dir(next))
 		return NULL;
 
 	if (req_op(req) == REQ_OP_WRITE_SAME &&
@@ -905,10 +904,6 @@ bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
 	if (bio_data_dir(bio) != rq_data_dir(rq))
 		return false;
 
-	/* must be same device */
-	if (rq->rq_disk != bio->bi_bdev->bd_disk)
-		return false;
-
 	/* only merge integrity protected bio into ditto rq */
 	if (blk_integrity_merge_bio(rq->q, rq, bio) == false)
 		return false;