From: Jens Axboe <axboe@kernel.dk>
Date: Tue, 18 Nov 2025 15:37:26 +0000 (-0700)
Subject: Revert "block: consider discard merge last"
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=caebce24f6a7f8315b1b87505b74066efb592d92;p=thirdparty%2Flinux.git

Revert "block: consider discard merge last"

This reverts commit 2516c246d01c23a5f5310e9ac78d9f8aad9b1d0e.

Suspected issues with discard merging post this patch, hence revert
it for now.

Link: https://lore.kernel.org/linux-block/26acdfdf-de13-430b-8c73-f890c7689a84@kernel.dk/
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/block/blk-merge.c b/block/blk-merge.c
index db08bc9060916..d3115d7469df0 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -712,10 +712,10 @@ static void blk_account_io_merge_request(struct request *req)
 static enum elv_merge blk_try_req_merge(struct request *req,
 					struct request *next)
 {
-	if (blk_rq_pos(req) + blk_rq_sectors(req) == blk_rq_pos(next))
-		return ELEVATOR_BACK_MERGE;
-	else if (blk_discard_mergable(req))
+	if (blk_discard_mergable(req))
 		return ELEVATOR_DISCARD_MERGE;
+	else if (blk_rq_pos(req) + blk_rq_sectors(req) == blk_rq_pos(next))
+		return ELEVATOR_BACK_MERGE;
 
 	return ELEVATOR_NO_MERGE;
 }
@@ -903,12 +903,12 @@ bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
 
 enum elv_merge blk_try_merge(struct request *rq, struct bio *bio)
 {
-	if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector)
+	if (blk_discard_mergable(rq))
+		return ELEVATOR_DISCARD_MERGE;
+	else if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector)
 		return ELEVATOR_BACK_MERGE;
 	else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector)
 		return ELEVATOR_FRONT_MERGE;
-	else if (blk_discard_mergable(rq))
-		return ELEVATOR_DISCARD_MERGE;
 	return ELEVATOR_NO_MERGE;
 }