block: don't bother checking the data direction for merges

Because it already is encoded in the opcode.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20241119161157.1328171-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-merge.c

@@ -864,9 +864,6 @@ 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))
-		return NULL;
-
 	if (req->bio && next->bio) {
 		/* Don't merge requests with different write hints. */
 		if (req->bio->bi_write_hint != next->bio->bi_write_hint)
@@ -986,10 +983,6 @@ bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
 	if (req_op(rq) != bio_op(bio))
 		return false;
 
-	/* different data direction or already started, don't merge */
-	if (bio_data_dir(bio) != rq_data_dir(rq))
-		return false;
-
 	/* don't merge across cgroup boundaries */
 	if (!blk_cgroup_mergeable(rq, bio))
 		return false;