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From: Uday Shankar <ushankar@purestorage.com>
To: Jens Axboe <axboe@kernel.dk>, Alasdair Kergon <agk@redhat.com>,
	Mike Snitzer <snitzer@kernel.org>
Cc: linux-block@vger.kernel.org, dm-devel@redhat.com,
	Uday Shankar <ushankar@purestorage.com>
Subject: [PATCH] blk-mq: enforce op-specific segment limits in blk_insert_cloned_request
Date: Wed, 15 Feb 2023 13:15:08 -0700	[thread overview]
Message-ID: <20230215201507.494152-1-ushankar@purestorage.com> (raw)

The block layer might merge together discard requests up until the
max_discard_segments limit is hit, but blk_insert_cloned_request checks
the segment count against max_segments regardless of the req op. This
can result in errors like the following when discards are issued through
a DM device and max_discard_segments exceeds max_segments for the queue
of the chosen underlying device.

blk_insert_cloned_request: over max segments limit. (256 > 129)

Fix this by looking at the req_op and enforcing the appropriate segment
limit - max_discard_segments for REQ_OP_DISCARDs and max_segments for
everything else.

Signed-off-by: Uday Shankar <ushankar@purestorage.com>
---
 block/blk-merge.c | 4 +---
 block/blk-mq.c    | 5 +++--
 block/blk.h       | 8 ++++++++
 3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/block/blk-merge.c b/block/blk-merge.c
index b7c193d67..7f663c2d3 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -588,9 +588,7 @@ EXPORT_SYMBOL(__blk_rq_map_sg);
 
 static inline unsigned int blk_rq_get_max_segments(struct request *rq)
 {
-	if (req_op(rq) == REQ_OP_DISCARD)
-		return queue_max_discard_segments(rq->q);
-	return queue_max_segments(rq->q);
+	return blk_queue_get_max_segments(rq->q, req_op(rq));
 }
 
 static inline unsigned int blk_rq_get_max_sectors(struct request *rq,
diff --git a/block/blk-mq.c b/block/blk-mq.c
index d3494a796..121b20230 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -3000,6 +3000,7 @@ blk_status_t blk_insert_cloned_request(struct request *rq)
 {
 	struct request_queue *q = rq->q;
 	unsigned int max_sectors = blk_queue_get_max_sectors(q, req_op(rq));
+	unsigned int max_segments = blk_queue_get_max_segments(q, req_op(rq));
 	blk_status_t ret;
 
 	if (blk_rq_sectors(rq) > max_sectors) {
@@ -3026,9 +3027,9 @@ blk_status_t blk_insert_cloned_request(struct request *rq)
 	 * original queue.
 	 */
 	rq->nr_phys_segments = blk_recalc_rq_segments(rq);
-	if (rq->nr_phys_segments > queue_max_segments(q)) {
+	if (rq->nr_phys_segments > max_segments) {
 		printk(KERN_ERR "%s: over max segments limit. (%hu > %hu)\n",
-			__func__, rq->nr_phys_segments, queue_max_segments(q));
+			__func__, rq->nr_phys_segments, max_segments);
 		return BLK_STS_IOERR;
 	}
 
diff --git a/block/blk.h b/block/blk.h
index f02381405..8d705c13a 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -169,6 +169,14 @@ static inline unsigned int blk_queue_get_max_sectors(struct request_queue *q,
 	return q->limits.max_sectors;
 }
 
+static inline unsigned int blk_queue_get_max_segments(struct request_queue *q,
+						      enum req_op op)
+{
+	if (op == REQ_OP_DISCARD)
+		return queue_max_discard_segments(q);
+	return queue_max_segments(q);
+}
+
 #ifdef CONFIG_BLK_DEV_INTEGRITY
 void blk_flush_integrity(void);
 bool __bio_integrity_endio(struct bio *);

base-commit: 6bea9ac7c6481c09eb2b61d7cd844fc64a526e3e
-- 
2.25.1


WARNING: multiple messages have this Message-ID (diff)
From: Uday Shankar <ushankar@purestorage.com>
To: Jens Axboe <axboe@kernel.dk>, Alasdair Kergon <agk@redhat.com>,
	Mike Snitzer <snitzer@kernel.org>
Cc: linux-block@vger.kernel.org, dm-devel@redhat.com,
	Uday Shankar <ushankar@purestorage.com>
Subject: [dm-devel] [PATCH] blk-mq: enforce op-specific segment limits in blk_insert_cloned_request
Date: Wed, 15 Feb 2023 13:15:08 -0700	[thread overview]
Message-ID: <20230215201507.494152-1-ushankar@purestorage.com> (raw)

The block layer might merge together discard requests up until the
max_discard_segments limit is hit, but blk_insert_cloned_request checks
the segment count against max_segments regardless of the req op. This
can result in errors like the following when discards are issued through
a DM device and max_discard_segments exceeds max_segments for the queue
of the chosen underlying device.

blk_insert_cloned_request: over max segments limit. (256 > 129)

Fix this by looking at the req_op and enforcing the appropriate segment
limit - max_discard_segments for REQ_OP_DISCARDs and max_segments for
everything else.

Signed-off-by: Uday Shankar <ushankar@purestorage.com>
---
 block/blk-merge.c | 4 +---
 block/blk-mq.c    | 5 +++--
 block/blk.h       | 8 ++++++++
 3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/block/blk-merge.c b/block/blk-merge.c
index b7c193d67..7f663c2d3 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -588,9 +588,7 @@ EXPORT_SYMBOL(__blk_rq_map_sg);
 
 static inline unsigned int blk_rq_get_max_segments(struct request *rq)
 {
-	if (req_op(rq) == REQ_OP_DISCARD)
-		return queue_max_discard_segments(rq->q);
-	return queue_max_segments(rq->q);
+	return blk_queue_get_max_segments(rq->q, req_op(rq));
 }
 
 static inline unsigned int blk_rq_get_max_sectors(struct request *rq,
diff --git a/block/blk-mq.c b/block/blk-mq.c
index d3494a796..121b20230 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -3000,6 +3000,7 @@ blk_status_t blk_insert_cloned_request(struct request *rq)
 {
 	struct request_queue *q = rq->q;
 	unsigned int max_sectors = blk_queue_get_max_sectors(q, req_op(rq));
+	unsigned int max_segments = blk_queue_get_max_segments(q, req_op(rq));
 	blk_status_t ret;
 
 	if (blk_rq_sectors(rq) > max_sectors) {
@@ -3026,9 +3027,9 @@ blk_status_t blk_insert_cloned_request(struct request *rq)
 	 * original queue.
 	 */
 	rq->nr_phys_segments = blk_recalc_rq_segments(rq);
-	if (rq->nr_phys_segments > queue_max_segments(q)) {
+	if (rq->nr_phys_segments > max_segments) {
 		printk(KERN_ERR "%s: over max segments limit. (%hu > %hu)\n",
-			__func__, rq->nr_phys_segments, queue_max_segments(q));
+			__func__, rq->nr_phys_segments, max_segments);
 		return BLK_STS_IOERR;
 	}
 
diff --git a/block/blk.h b/block/blk.h
index f02381405..8d705c13a 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -169,6 +169,14 @@ static inline unsigned int blk_queue_get_max_sectors(struct request_queue *q,
 	return q->limits.max_sectors;
 }
 
+static inline unsigned int blk_queue_get_max_segments(struct request_queue *q,
+						      enum req_op op)
+{
+	if (op == REQ_OP_DISCARD)
+		return queue_max_discard_segments(q);
+	return queue_max_segments(q);
+}
+
 #ifdef CONFIG_BLK_DEV_INTEGRITY
 void blk_flush_integrity(void);
 bool __bio_integrity_endio(struct bio *);

base-commit: 6bea9ac7c6481c09eb2b61d7cd844fc64a526e3e
-- 
2.25.1

--
dm-devel mailing list
dm-devel@redhat.com
https://listman.redhat.com/mailman/listinfo/dm-devel


             reply	other threads:[~2023-02-15 20:16 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-15 20:15 Uday Shankar [this message]
2023-02-15 20:15 ` [dm-devel] [PATCH] blk-mq: enforce op-specific segment limits in blk_insert_cloned_request Uday Shankar
2023-02-16  6:09 ` Christoph Hellwig
2023-02-16  6:09   ` [dm-devel] " Christoph Hellwig
2023-02-16 19:27   ` Uday Shankar
2023-02-16 19:27     ` [dm-devel] " Uday Shankar
2023-02-17  0:13     ` Mike Snitzer
2023-02-17  0:13       ` [dm-devel] " Mike Snitzer
2023-02-17 16:16     ` [PATCH] " Christoph Hellwig
2023-02-17 16:16       ` [dm-devel] " Christoph Hellwig
2023-02-17 16:43       ` [dm-devel] " Mike Snitzer
2023-02-17 16:43         ` Mike Snitzer
2023-02-17 21:41         ` Uday Shankar
2023-02-17 21:41           ` [dm-devel] " Uday Shankar
2023-02-16 13:06 ` [PATCH] " kernel test robot
2023-02-16 13:06   ` [dm-devel] " kernel test robot

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