[PATCH] block: return ELEVATOR_DISCARD_MERGE if possible

[PATCH] block: return ELEVATOR_DISCARD_MERGE if possible

[Gwendal Grignou]

From: Ming Lei <ming.lei@redhat.com>

When merging one bio to request, if they are discard IO and the queue
supports multi-range discard, we need to return ELEVATOR_DISCARD_MERGE
because both block core and related drivers(nvme, virtio-blk) doesn't
handle mixed discard io merge(traditional IO merge together with
discard merge) well.

Fix the issue by returning ELEVATOR_DISCARD_MERGE in this situation,
so both blk-mq and drivers just need to handle multi-range discard.

Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Fixes: 2705dfb20947 ("block: fix discard request merge")
Link: https://lore.kernel.org/r/20210729034226.1591070-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

commit 866663b7b52d2 upstream.

Similar to commit 87aa69aa10b42 ("block: return ELEVATOR_DISCARD_MERGE if possible")
in 5.10 kernel.

Conflicts:
   block/blk-merge.c: function at a different place.
   block/mq-deadline-main.c: not in 5.4, use mq-deadline.c instead.

Cc: <stable@vger.kernel.org> # 5.4.y
Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
---
 block/bfq-iosched.c    |  3 +++
 block/blk-merge.c      | 15 ---------------
 block/elevator.c       |  3 +++
 block/mq-deadline.c    |  2 ++
 include/linux/blkdev.h | 16 ++++++++++++++++
 5 files changed, 24 insertions(+), 15 deletions(-)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 1d443d17cf7c5..d46806182b051 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -2251,6 +2251,9 @@ 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 a62692d135660..5219064cd72bb 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -721,21 +721,6 @@ static void blk_account_io_merge(struct request *req)
 		part_stat_unlock();
 	}
 }
-/*
- * 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 78805c74ea8a4..3ba826230c578 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -337,6 +337,9 @@ 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.c b/block/mq-deadline.c
index 19c6922e85f1b..6d6dda5cfffa3 100644
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c
@@ -452,6 +452,8 @@ 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 8cc766743270f..308c2d8cdca19 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1409,6 +1409,22 @@ 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);
-- 
2.36.1.124.g0e6072fb45-goog

Re: [PATCH] block: return ELEVATOR_DISCARD_MERGE if possible

[Greg KH]

On Sat, May 21, 2022 at 11:56:26AM -0700, Gwendal Grignou wrote:
> From: Ming Lei <ming.lei@redhat.com>
> 
> When merging one bio to request, if they are discard IO and the queue
> supports multi-range discard, we need to return ELEVATOR_DISCARD_MERGE
> because both block core and related drivers(nvme, virtio-blk) doesn't
> handle mixed discard io merge(traditional IO merge together with
> discard merge) well.
> 
> Fix the issue by returning ELEVATOR_DISCARD_MERGE in this situation,
> so both blk-mq and drivers just need to handle multi-range discard.
> 
> Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name>
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
> Fixes: 2705dfb20947 ("block: fix discard request merge")
> Link: https://lore.kernel.org/r/20210729034226.1591070-1-ming.lei@redhat.com
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> 
> commit 866663b7b52d2 upstream.
> 
> Similar to commit 87aa69aa10b42 ("block: return ELEVATOR_DISCARD_MERGE if possible")
> in 5.10 kernel.
> 
> Conflicts:
>    block/blk-merge.c: function at a different place.
>    block/mq-deadline-main.c: not in 5.4, use mq-deadline.c instead.
> 
> Cc: <stable@vger.kernel.org> # 5.4.y
> Signed-off-by: Gwendal Grignou <gwendal@chromium.org>

Now queued up, thanks.

greg k-h

[PATCH] block: return ELEVATOR_DISCARD_MERGE if possible

[Ming Lei]

When merging one bio to request, if they are discard IO and the queue
supports multi-range discard, we need to return ELEVATOR_DISCARD_MERGE
because both block core and related drivers(nvme, virtio-blk) doesn't
handle mixed discard io merge(traditional IO merge together with
discard merge) well.

Fix the issue by returning ELEVATOR_DISCARD_MERGE in this situation,
so both blk-mq and drivers just need to handle multi-range discard.

Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 block/bfq-iosched.c      |  3 +++
 block/blk-merge.c        | 16 ----------------
 block/elevator.c         |  3 +++
 block/mq-deadline-main.c |  2 ++
 include/linux/blkdev.h   | 16 ++++++++++++++++
 5 files changed, 24 insertions(+), 16 deletions(-)

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);
-- 
2.31.1

Re: [PATCH] block: return ELEVATOR_DISCARD_MERGE if possible

[Oleksandr Natalenko]

On čtvrtek 29. července 2021 5:42:26 CEST Ming Lei wrote:
> When merging one bio to request, if they are discard IO and the queue
> supports multi-range discard, we need to return ELEVATOR_DISCARD_MERGE
> because both block core and related drivers(nvme, virtio-blk) doesn't
> handle mixed discard io merge(traditional IO merge together with
> discard merge) well.
> 
> Fix the issue by returning ELEVATOR_DISCARD_MERGE in this situation,
> so both blk-mq and drivers just need to handle multi-range discard.
> 
> Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name>
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
>  block/bfq-iosched.c      |  3 +++
>  block/blk-merge.c        | 16 ----------------
>  block/elevator.c         |  3 +++
>  block/mq-deadline-main.c |  2 ++
>  include/linux/blkdev.h   | 16 ++++++++++++++++
>  5 files changed, 24 insertions(+), 16 deletions(-)
> 
> 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);

Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>

Also,

Fixes: ?

and possibly:

CC: stable@ # v5.x?

Thanks.

-- 
Oleksandr Natalenko (post-factum)

Re: [PATCH] block: return ELEVATOR_DISCARD_MERGE if possible

[Ming Lei]

On Thu, Jul 29, 2021 at 09:17:28AM +0200, Oleksandr Natalenko wrote:
> On čtvrtek 29. července 2021 5:42:26 CEST Ming Lei wrote:
> > When merging one bio to request, if they are discard IO and the queue
> > supports multi-range discard, we need to return ELEVATOR_DISCARD_MERGE
> > because both block core and related drivers(nvme, virtio-blk) doesn't
> > handle mixed discard io merge(traditional IO merge together with
> > discard merge) well.
> > 
> > Fix the issue by returning ELEVATOR_DISCARD_MERGE in this situation,
> > so both blk-mq and drivers just need to handle multi-range discard.
> > 
> > Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name>
> > Signed-off-by: Ming Lei <ming.lei@redhat.com>
> > ---
> >  block/bfq-iosched.c      |  3 +++
> >  block/blk-merge.c        | 16 ----------------
> >  block/elevator.c         |  3 +++
> >  block/mq-deadline-main.c |  2 ++
> >  include/linux/blkdev.h   | 16 ++++++++++++++++
> >  5 files changed, 24 insertions(+), 16 deletions(-)
> > 
> > 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);
> 
> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
> 
> Also,
> 
> Fixes: ?

Fixes: 2705dfb20947 ("block: fix discard request merge")

In theory, the fixes should be 1e739730c5b9 ("block: optionally merge
discontiguous discard bios into a single request"). The reason why it
isn't be triggered before 2705dfb20947 is that the nr_segment of each
bio is exactly 1 for multi-range device.

> 
> and possibly:
> 
> CC: stable@ # v5.x?

CC: stable@ # v5.13


Thanks,
Ming

Re: [PATCH] block: return ELEVATOR_DISCARD_MERGE if possible

[Ming Lei]

On Thu, Jul 29, 2021 at 11:42:26AM +0800, Ming Lei wrote:
> When merging one bio to request, if they are discard IO and the queue
> supports multi-range discard, we need to return ELEVATOR_DISCARD_MERGE
> because both block core and related drivers(nvme, virtio-blk) doesn't
> handle mixed discard io merge(traditional IO merge together with
> discard merge) well.
> 
> Fix the issue by returning ELEVATOR_DISCARD_MERGE in this situation,
> so both blk-mq and drivers just need to handle multi-range discard.
> 
> Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name>
> Signed-off-by: Ming Lei <ming.lei@redhat.com>

Hello Jens and Guys,

Ping...


Thanks,
Ming

Re: [PATCH] block: return ELEVATOR_DISCARD_MERGE if possible

[Oleksandr Natalenko]

Hello.

On čtvrtek 5. srpna 2021 5:35:00 CEST Ming Lei wrote:
> On Thu, Jul 29, 2021 at 11:42:26AM +0800, Ming Lei wrote:
> > When merging one bio to request, if they are discard IO and the queue
> > supports multi-range discard, we need to return ELEVATOR_DISCARD_MERGE
> > because both block core and related drivers(nvme, virtio-blk) doesn't
> > handle mixed discard io merge(traditional IO merge together with
> > discard merge) well.
> > 
> > Fix the issue by returning ELEVATOR_DISCARD_MERGE in this situation,
> > so both blk-mq and drivers just need to handle multi-range discard.
> > 
> > Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name>
> > Signed-off-by: Ming Lei <ming.lei@redhat.com>
> 
> Hello Jens and Guys,
> 
> Ping...

Ping v2 here… I'm still running a couple of affected systems with this patch, 
and the issue doesn't pop up any more.

Thanks.

-- 
Oleksandr Natalenko (post-factum)

Re: [PATCH] block: return ELEVATOR_DISCARD_MERGE if possible

[Jens Axboe]

On 8/4/21 9:35 PM, Ming Lei wrote:
> On Thu, Jul 29, 2021 at 11:42:26AM +0800, Ming Lei wrote:
>> When merging one bio to request, if they are discard IO and the queue
>> supports multi-range discard, we need to return ELEVATOR_DISCARD_MERGE
>> because both block core and related drivers(nvme, virtio-blk) doesn't
>> handle mixed discard io merge(traditional IO merge together with
>> discard merge) well.
>>
>> Fix the issue by returning ELEVATOR_DISCARD_MERGE in this situation,
>> so both blk-mq and drivers just need to handle multi-range discard.
>>
>> Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name>
>> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> 
> Hello Jens and Guys,
> 
> Ping...

Since this isn't a new regression this release and since this kind
of change always makes me a bit nervous, any objections to queueing
it up for 5.15 with the stable/fixes tags?

-- 
Jens Axboe

Re: [PATCH] block: return ELEVATOR_DISCARD_MERGE if possible

[Ming Lei]

On Mon, Aug 09, 2021 at 02:36:25PM -0600, Jens Axboe wrote:
> On 8/4/21 9:35 PM, Ming Lei wrote:
> > On Thu, Jul 29, 2021 at 11:42:26AM +0800, Ming Lei wrote:
> >> When merging one bio to request, if they are discard IO and the queue
> >> supports multi-range discard, we need to return ELEVATOR_DISCARD_MERGE
> >> because both block core and related drivers(nvme, virtio-blk) doesn't
> >> handle mixed discard io merge(traditional IO merge together with
> >> discard merge) well.
> >>
> >> Fix the issue by returning ELEVATOR_DISCARD_MERGE in this situation,
> >> so both blk-mq and drivers just need to handle multi-range discard.
> >>
> >> Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name>
> >> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> > 
> > Hello Jens and Guys,
> > 
> > Ping...
> 
> Since this isn't a new regression this release and since this kind
> of change always makes me a bit nervous, any objections to queueing
> it up for 5.15 with the stable/fixes tags?

Fine, will post a new version with fixes tag.

-- 
Ming

Re: [PATCH] block: return ELEVATOR_DISCARD_MERGE if possible

[Jens Axboe]

On 8/9/21 8:47 PM, Ming Lei wrote:
> On Mon, Aug 09, 2021 at 02:36:25PM -0600, Jens Axboe wrote:
>> On 8/4/21 9:35 PM, Ming Lei wrote:
>>> On Thu, Jul 29, 2021 at 11:42:26AM +0800, Ming Lei wrote:
>>>> When merging one bio to request, if they are discard IO and the queue
>>>> supports multi-range discard, we need to return ELEVATOR_DISCARD_MERGE
>>>> because both block core and related drivers(nvme, virtio-blk) doesn't
>>>> handle mixed discard io merge(traditional IO merge together with
>>>> discard merge) well.
>>>>
>>>> Fix the issue by returning ELEVATOR_DISCARD_MERGE in this situation,
>>>> so both blk-mq and drivers just need to handle multi-range discard.
>>>>
>>>> Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name>
>>>> Signed-off-by: Ming Lei <ming.lei@redhat.com>
>>>
>>> Hello Jens and Guys,
>>>
>>> Ping...
>>
>> Since this isn't a new regression this release and since this kind
>> of change always makes me a bit nervous, any objections to queueing
>> it up for 5.15 with the stable/fixes tags?
> 
> Fine, will post a new version with fixes tag.

Sorry if I wasn't clear, I mean are you fine with queueing this for
5.15? I already did add the fixes tag.

-- 
Jens Axboe

Re: [PATCH] block: return ELEVATOR_DISCARD_MERGE if possible

[Ming Lei]

On Mon, Aug 09, 2021 at 08:55:16PM -0600, Jens Axboe wrote:
> On 8/9/21 8:47 PM, Ming Lei wrote:
> > On Mon, Aug 09, 2021 at 02:36:25PM -0600, Jens Axboe wrote:
> >> On 8/4/21 9:35 PM, Ming Lei wrote:
> >>> On Thu, Jul 29, 2021 at 11:42:26AM +0800, Ming Lei wrote:
> >>>> When merging one bio to request, if they are discard IO and the queue
> >>>> supports multi-range discard, we need to return ELEVATOR_DISCARD_MERGE
> >>>> because both block core and related drivers(nvme, virtio-blk) doesn't
> >>>> handle mixed discard io merge(traditional IO merge together with
> >>>> discard merge) well.
> >>>>
> >>>> Fix the issue by returning ELEVATOR_DISCARD_MERGE in this situation,
> >>>> so both blk-mq and drivers just need to handle multi-range discard.
> >>>>
> >>>> Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name>
> >>>> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> >>>
> >>> Hello Jens and Guys,
> >>>
> >>> Ping...
> >>
> >> Since this isn't a new regression this release and since this kind
> >> of change always makes me a bit nervous, any objections to queueing
> >> it up for 5.15 with the stable/fixes tags?
> > 
> > Fine, will post a new version with fixes tag.
> 
> Sorry if I wasn't clear, I mean are you fine with queueing this for
> 5.15? I already did add the fixes tag.

Sorry for misunderstanding your point, yeah, I am fine with queuing in
5.15.


Thanks,
Ming