linux-kernel - [PATCH] block: don't merge bios with different app

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Message-ID: <20260106200838.152055-1-csander@purestorage.com>
Date: Tue,  6 Jan 2026 13:08:37 -0700
From: Caleb Sander Mateos <csander@...estorage.com>
To: Jens Axboe <axboe@...nel.dk>
Cc: Kanchan Joshi <joshi.k@...sung.com>,
	Ming Lei <ming.lei@...hat.com>,
	Caleb Sander Mateos <csander@...estorage.com>,
	linux-block@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] block: don't merge bios with different app_tags

nvme_set_app_tag() uses the app_tag value from the bio_integrity_payload
of the struct request's first bio. This assumes all the request's bios
have the same app_tag. However, it is possible for bios with different
app_tag values to be merged into a single request.
Add a check in blk_integrity_merge_{bio,rq}() to prevent the merging of
bios/requests with different app_tag values if BIP_CHECK_APPTAG is set.

Signed-off-by: Caleb Sander Mateos <csander@...estorage.com>
Fixes: 3d8b5a22d404 ("block: add support to pass user meta buffer")
---
 block/blk-integrity.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/block/blk-integrity.c b/block/blk-integrity.c
index 9b27963680dc..964eebbee14d 100644
--- a/block/blk-integrity.c
+++ b/block/blk-integrity.c
@@ -138,18 +138,25 @@ int blk_rq_integrity_map_user(struct request *rq, void __user *ubuf,
 EXPORT_SYMBOL_GPL(blk_rq_integrity_map_user);
 
 bool blk_integrity_merge_rq(struct request_queue *q, struct request *req,
 			    struct request *next)
 {
+	struct bio_integrity_payload *bip, *bip_next;
+
 	if (blk_integrity_rq(req) == 0 && blk_integrity_rq(next) == 0)
 		return true;
 
 	if (blk_integrity_rq(req) == 0 || blk_integrity_rq(next) == 0)
 		return false;
 
-	if (bio_integrity(req->bio)->bip_flags !=
-	    bio_integrity(next->bio)->bip_flags)
+	bip = bio_integrity(req->bio);
+	bip_next = bio_integrity(next->bio);
+	if (bip->bip_flags != bip_next->bip_flags)
+		return false;
+
+	if (bip->bip_flags & BIP_CHECK_APPTAG &&
+	    bip->app_tag != bip_next->app_tag)
 		return false;
 
 	if (req->nr_integrity_segments + next->nr_integrity_segments >
 	    q->limits.max_integrity_segments)
 		return false;
@@ -161,19 +168,25 @@ bool blk_integrity_merge_rq(struct request_queue *q, struct request *req,
 }
 
 bool blk_integrity_merge_bio(struct request_queue *q, struct request *req,
 			     struct bio *bio)
 {
+	struct bio_integrity_payload *bip, *bip_bio = bio_integrity(bio);
 	int nr_integrity_segs;
 
-	if (blk_integrity_rq(req) == 0 && bio_integrity(bio) == NULL)
+	if (blk_integrity_rq(req) == 0 && bip_bio == NULL)
 		return true;
 
-	if (blk_integrity_rq(req) == 0 || bio_integrity(bio) == NULL)
+	if (blk_integrity_rq(req) == 0 || bip_bio == NULL)
+		return false;
+
+	bip = bio_integrity(req->bio);
+	if (bip->bip_flags != bip_bio->bip_flags)
 		return false;
 
-	if (bio_integrity(req->bio)->bip_flags != bio_integrity(bio)->bip_flags)
+	if (bip->bip_flags & BIP_CHECK_APPTAG &&
+	    bip->app_tag != bip_bio->app_tag)
 		return false;
 
 	nr_integrity_segs = blk_rq_count_integrity_sg(q, bio);
 	if (req->nr_integrity_segments + nr_integrity_segs >
 	    q->limits.max_integrity_segments)
-- 
2.45.2