Re: New warning in nvme_setup_discard

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 727955918563..673a634eadd9 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c

@@ -2361,6 +2361,9 @@ static int bfq_request_merge(struct request_queue *q,

struct request **req, __rq = bfq_find_rq_fmerge(bfqd, bio, q);
 	if (__rq && elv_bio_merge_ok(__rq, bio)) {
 		*req = __rq;
+
+		if (blk_discard_mergable(__rq))
+			return ELEVATOR_DISCARD_MERGE;
 		return ELEVATOR_FRONT_MERGE;
 	}

diff --git a/block/blk-merge.c b/block/blk-merge.c
index a11b3b53717e..f8707ff7e2fc 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c

@@ -705,22 +705,6 @@ static void blk_account_io_merge_request(struct request

*req) }
 }

-/*
- * Two cases of handling DISCARD merge:
- * If max_discard_segments > 1, the driver takes every bio
- * as a range and send them to controller together. The ranges
- * needn't to be contiguous.
- * Otherwise, the bios/requests will be handled as same as
- * others which should be contiguous.
- */
-static inline bool blk_discard_mergable(struct request *req)
-{
-	if (req_op(req) == REQ_OP_DISCARD &&
-	    queue_max_discard_segments(req->q) > 1)
-		return true;
-	return false;
-}
-
 static enum elv_merge blk_try_req_merge(struct request *req,
 					struct request *next)
 {

diff --git a/block/elevator.c b/block/elevator.c
index 52ada14cfe45..a5fe2615ec0f 100644
--- a/block/elevator.c
+++ b/block/elevator.c

@@ -336,6 +336,9 @@ enum elv_merge elv_merge(struct request_queue *q, struct

request **req, __rq = elv_rqhash_find(q, bio->bi_iter.bi_sector);
 	if (__rq && elv_bio_merge_ok(__rq, bio)) {
 		*req = __rq;
+
+		if (blk_discard_mergable(__rq))
+			return ELEVATOR_DISCARD_MERGE;
 		return ELEVATOR_BACK_MERGE;
 	}

diff --git a/block/mq-deadline-main.c b/block/mq-deadline-main.c
index 6f612e6dc82b..294be0c0db65 100644
--- a/block/mq-deadline-main.c
+++ b/block/mq-deadline-main.c

@@ -677,6 +677,8 @@ static int dd_request_merge(struct request_queue *q,

struct request **rq,

 		if (elv_bio_merge_ok(__rq, bio)) {
 			*rq = __rq;
+			if (blk_discard_mergable(__rq))
+				return ELEVATOR_DISCARD_MERGE;
 			return ELEVATOR_FRONT_MERGE;
 		}
 	}

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 3177181c4326..87f00292fd7a 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h

@@ -1521,6 +1521,22 @@ static inline int

queue_limit_discard_alignment(struct queue_limits *lim, sector return
offset << SECTOR_SHIFT;
 }

+/*
+ * Two cases of handling DISCARD merge:
+ * If max_discard_segments > 1, the driver takes every bio
+ * as a range and send them to controller together. The ranges
+ * needn't to be contiguous.
+ * Otherwise, the bios/requests will be handled as same as
+ * others which should be contiguous.
+ */
+static inline bool blk_discard_mergable(struct request *req)
+{
+	if (req_op(req) == REQ_OP_DISCARD &&
+	    queue_max_discard_segments(req->q) > 1)
+		return true;
+	return false;
+}
+
 static inline int bdev_discard_alignment(struct block_device *bdev)
 {
 	struct request_queue *q = bdev_get_queue(bdev);