[PATCH 1/3] dm-integrity: fix mismatched queue limits

[PATCH 1/3] dm-integrity: fix mismatched queue limits

[Keith Busch]

From: Keith Busch <kbusch@kernel.org>

A user can integritysetup a device with a backing device using a 4k
logical block size, but request the dm device use 1k or 2k. This
mismatch creates an inconsistency such that the dm device would report
limits for IO that it can't actually execute. Fix this by using the
backing device's limits if they are larger.

Signed-off-by: Keith Busch <kbusch@kernel.org>
---
 drivers/md/dm-integrity.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c
index 06e805902151c..8dfd498ed1ffd 100644
--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -4047,9 +4047,15 @@ static void dm_integrity_io_hints(struct dm_target *ti, struct queue_limits *lim
 	struct dm_integrity_c *ic = ti->private;
 
 	if (ic->sectors_per_block > 1) {
-		limits->logical_block_size = ic->sectors_per_block << SECTOR_SHIFT;
-		limits->physical_block_size = ic->sectors_per_block << SECTOR_SHIFT;
-		limits->io_min = ic->sectors_per_block << SECTOR_SHIFT;
+		limits->logical_block_size =
+				max(limits->logical_block_size,
+				    ic->sectors_per_block << SECTOR_SHIFT);
+		limits->physical_block_size =
+				max(limits->physical_block_size,
+				    ic->sectors_per_block << SECTOR_SHIFT);
+		limits->io_min =
+				max(limits->io_min,
+				    ic->sectors_per_block << SECTOR_SHIFT);
 		limits->dma_alignment = limits->logical_block_size - 1;
 		limits->discard_granularity = ic->sectors_per_block << SECTOR_SHIFT;
 	}
-- 
2.52.0

[PATCH 2/3] dm-integrity: always set the io hints

[Keith Busch]

From: Keith Busch <kbusch@kernel.org>

Don't depend on the defaults to be what is desired if the integrity
device was set up with 512b sector size. Always set the queue limits to
be at least what the device mapper wants.

Signed-off-by: Keith Busch <kbusch@kernel.org>
---
 drivers/md/dm-integrity.c | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c
index 8dfd498ed1ffd..d64c15c761d0a 100644
--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -4046,19 +4046,14 @@ static void dm_integrity_io_hints(struct dm_target *ti, struct queue_limits *lim
 {
 	struct dm_integrity_c *ic = ti->private;
 
-	if (ic->sectors_per_block > 1) {
-		limits->logical_block_size =
-				max(limits->logical_block_size,
-				    ic->sectors_per_block << SECTOR_SHIFT);
-		limits->physical_block_size =
-				max(limits->physical_block_size,
-				    ic->sectors_per_block << SECTOR_SHIFT);
-		limits->io_min =
-				max(limits->io_min,
-				    ic->sectors_per_block << SECTOR_SHIFT);
-		limits->dma_alignment = limits->logical_block_size - 1;
-		limits->discard_granularity = ic->sectors_per_block << SECTOR_SHIFT;
-	}
+	limits->logical_block_size = max(limits->logical_block_size,
+			    ic->sectors_per_block << SECTOR_SHIFT);
+	limits->physical_block_size = max(limits->physical_block_size,
+			    ic->sectors_per_block << SECTOR_SHIFT);
+	limits->io_min = max(limits->io_min,
+			    ic->sectors_per_block << SECTOR_SHIFT);
+	limits->dma_alignment = limits->logical_block_size - 1;
+	limits->discard_granularity = ic->sectors_per_block << SECTOR_SHIFT;
 
 	if (!ic->internal_hash) {
 		struct blk_integrity *bi = &limits->integrity;
-- 
2.52.0

[PATCH 3/3] dm: provide helper to set stacked limits

[Keith Busch]

From: Keith Busch <kbusch@kernel.org>

There are multiple device mappers that set up their stacking limits
exactly the same for the logical, physical and minimum IO queue limits.
Provide a helper for it.

Signed-off-by: Keith Busch <kbusch@kernel.org>
---
 drivers/md/dm-crypt.c         |  6 +-----
 drivers/md/dm-integrity.c     |  7 +------
 drivers/md/dm-verity-target.c |  8 +-------
 drivers/md/dm-writecache.c    | 10 +---------
 include/linux/device-mapper.h |  7 +++++++
 5 files changed, 11 insertions(+), 27 deletions(-)

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 885208a82c55f..60642cee8609d 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -3684,11 +3684,7 @@ static void crypt_io_hints(struct dm_target *ti, struct queue_limits *limits)
 {
 	struct crypt_config *cc = ti->private;
 
-	limits->logical_block_size =
-		max_t(unsigned int, limits->logical_block_size, cc->sector_size);
-	limits->physical_block_size =
-		max_t(unsigned int, limits->physical_block_size, cc->sector_size);
-	limits->io_min = max_t(unsigned int, limits->io_min, cc->sector_size);
+	dm_stack_bs_limits(limits, cc->sector_size);
 	limits->dma_alignment = limits->logical_block_size - 1;
 
 	/*
diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c
index d64c15c761d0a..65c30dec82220 100644
--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -4046,12 +4046,7 @@ static void dm_integrity_io_hints(struct dm_target *ti, struct queue_limits *lim
 {
 	struct dm_integrity_c *ic = ti->private;
 
-	limits->logical_block_size = max(limits->logical_block_size,
-			    ic->sectors_per_block << SECTOR_SHIFT);
-	limits->physical_block_size = max(limits->physical_block_size,
-			    ic->sectors_per_block << SECTOR_SHIFT);
-	limits->io_min = max(limits->io_min,
-			    ic->sectors_per_block << SECTOR_SHIFT);
+	dm_stack_bs_limits(limits, ic->sectors_per_block << SECTOR_SHIFT);
 	limits->dma_alignment = limits->logical_block_size - 1;
 	limits->discard_granularity = ic->sectors_per_block << SECTOR_SHIFT;
 
diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c
index e1d435c79e96c..9a9847f94c460 100644
--- a/drivers/md/dm-verity-target.c
+++ b/drivers/md/dm-verity-target.c
@@ -1011,13 +1011,7 @@ static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
 {
 	struct dm_verity *v = ti->private;
 
-	if (limits->logical_block_size < 1 << v->data_dev_block_bits)
-		limits->logical_block_size = 1 << v->data_dev_block_bits;
-
-	if (limits->physical_block_size < 1 << v->data_dev_block_bits)
-		limits->physical_block_size = 1 << v->data_dev_block_bits;
-
-	limits->io_min = limits->logical_block_size;
+	dm_stack_bs_limits(limits, 1 << v->data_dev_block_bits);
 
 	/*
 	 * Similar to what dm-crypt does, opt dm-verity out of support for
diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c
index 98bd945f6da7b..493f5202ad042 100644
--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -1640,17 +1640,9 @@ static void writecache_io_hints(struct dm_target *ti, struct queue_limits *limit
 {
 	struct dm_writecache *wc = ti->private;
 
-	if (limits->logical_block_size < wc->block_size)
-		limits->logical_block_size = wc->block_size;
-
-	if (limits->physical_block_size < wc->block_size)
-		limits->physical_block_size = wc->block_size;
-
-	if (limits->io_min < wc->block_size)
-		limits->io_min = wc->block_size;
+	dm_stack_bs_limits(limits, wc->block_size);
 }
 
-
 static void writecache_writeback_endio(struct bio *bio)
 {
 	struct writeback_struct *wb = container_of(bio, struct writeback_struct, bio);
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 38f625af6ab47..cd4faaf5d4275 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -755,4 +755,11 @@ static inline unsigned long to_bytes(sector_t n)
 	return (n << SECTOR_SHIFT);
 }
 
+static inline void dm_stack_bs_limits(struct queue_limits *limits, unsigned int bs)
+{
+	limits->logical_block_size = max(limits->logical_block_size, bs);
+	limits->physical_block_size = max(limits->physical_block_size, bs);
+	limits->io_min = max(limits->io_min, bs);
+}
+
 #endif	/* _LINUX_DEVICE_MAPPER_H */
-- 
2.52.0

Re: [PATCH 1/3] dm-integrity: fix mismatched queue limits

[Benjamin Marzinski]

On Wed, Mar 25, 2026 at 12:36:06PM -0700, Keith Busch wrote:
> From: Keith Busch <kbusch@kernel.org>
> 
> A user can integritysetup a device with a backing device using a 4k
> logical block size, but request the dm device use 1k or 2k. This
> mismatch creates an inconsistency such that the dm device would report
> limits for IO that it can't actually execute. Fix this by using the
> backing device's limits if they are larger.
> 
> Signed-off-by: Keith Busch <kbusch@kernel.org>
> ---
>  drivers/md/dm-integrity.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c
> index 06e805902151c..8dfd498ed1ffd 100644
> --- a/drivers/md/dm-integrity.c
> +++ b/drivers/md/dm-integrity.c
> @@ -4047,9 +4047,15 @@ static void dm_integrity_io_hints(struct dm_target *ti, struct queue_limits *lim
>  	struct dm_integrity_c *ic = ti->private;
>  
>  	if (ic->sectors_per_block > 1) {
> -		limits->logical_block_size = ic->sectors_per_block << SECTOR_SHIFT;
> -		limits->physical_block_size = ic->sectors_per_block << SECTOR_SHIFT;
> -		limits->io_min = ic->sectors_per_block << SECTOR_SHIFT;
> +		limits->logical_block_size =
> +				max(limits->logical_block_size,
> +				    ic->sectors_per_block << SECTOR_SHIFT);
> +		limits->physical_block_size =
> +				max(limits->physical_block_size,
> +				    ic->sectors_per_block << SECTOR_SHIFT);
> +		limits->io_min =
> +				max(limits->io_min,
> +				    ic->sectors_per_block << SECTOR_SHIFT);
>  		limits->dma_alignment = limits->logical_block_size - 1;
>  		limits->discard_granularity = ic->sectors_per_block << SECTOR_SHIFT;

Shouldn't this also respect the underlying device's discard_granularity?

-Ben

>  	}
> -- 
> 2.52.0
> 

Re: [PATCH 1/3] dm-integrity: fix mismatched queue limits

[Keith Busch]

On Fri, Mar 27, 2026 at 03:41:50PM -0400, Benjamin Marzinski wrote:
> > @@ -4047,9 +4047,15 @@ static void dm_integrity_io_hints(struct dm_target *ti, struct queue_limits *lim
> >  	struct dm_integrity_c *ic = ti->private;
> >  
> >  	if (ic->sectors_per_block > 1) {
> > -		limits->logical_block_size = ic->sectors_per_block << SECTOR_SHIFT;
> > -		limits->physical_block_size = ic->sectors_per_block << SECTOR_SHIFT;
> > -		limits->io_min = ic->sectors_per_block << SECTOR_SHIFT;
> > +		limits->logical_block_size =
> > +				max(limits->logical_block_size,
> > +				    ic->sectors_per_block << SECTOR_SHIFT);
> > +		limits->physical_block_size =
> > +				max(limits->physical_block_size,
> > +				    ic->sectors_per_block << SECTOR_SHIFT);
> > +		limits->io_min =
> > +				max(limits->io_min,
> > +				    ic->sectors_per_block << SECTOR_SHIFT);
> >  		limits->dma_alignment = limits->logical_block_size - 1;
> >  		limits->discard_granularity = ic->sectors_per_block << SECTOR_SHIFT;
> 
> Shouldn't this also respect the underlying device's discard_granularity?

It doesn't appear to. I left it unchanged as I'm not very familiar with
this device mapper, so that seemed safer. But I thought it was fine as
is: this dm doesn't appear to forward discards, so the underlying
device's constraints aren't brought into the operation. It looks like it
just sets a "DISCARD_FILLER" pattern into metadata.

Re: [PATCH 1/3] dm-integrity: fix mismatched queue limits

[Mikulas Patocka]

Hi

I accepted all three patches.

Mikulas



On Wed, 25 Mar 2026, Keith Busch wrote:

> From: Keith Busch <kbusch@kernel.org>
> 
> A user can integritysetup a device with a backing device using a 4k
> logical block size, but request the dm device use 1k or 2k. This
> mismatch creates an inconsistency such that the dm device would report
> limits for IO that it can't actually execute. Fix this by using the
> backing device's limits if they are larger.
> 
> Signed-off-by: Keith Busch <kbusch@kernel.org>
> ---
>  drivers/md/dm-integrity.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c
> index 06e805902151c..8dfd498ed1ffd 100644
> --- a/drivers/md/dm-integrity.c
> +++ b/drivers/md/dm-integrity.c
> @@ -4047,9 +4047,15 @@ static void dm_integrity_io_hints(struct dm_target *ti, struct queue_limits *lim
>  	struct dm_integrity_c *ic = ti->private;
>  
>  	if (ic->sectors_per_block > 1) {
> -		limits->logical_block_size = ic->sectors_per_block << SECTOR_SHIFT;
> -		limits->physical_block_size = ic->sectors_per_block << SECTOR_SHIFT;
> -		limits->io_min = ic->sectors_per_block << SECTOR_SHIFT;
> +		limits->logical_block_size =
> +				max(limits->logical_block_size,
> +				    ic->sectors_per_block << SECTOR_SHIFT);
> +		limits->physical_block_size =
> +				max(limits->physical_block_size,
> +				    ic->sectors_per_block << SECTOR_SHIFT);
> +		limits->io_min =
> +				max(limits->io_min,
> +				    ic->sectors_per_block << SECTOR_SHIFT);
>  		limits->dma_alignment = limits->logical_block_size - 1;
>  		limits->discard_granularity = ic->sectors_per_block << SECTOR_SHIFT;
>  	}
> -- 
> 2.52.0
> 

Re: [PATCH 1/3] dm-integrity: fix mismatched queue limits

[Benjamin Marzinski]

On Fri, Mar 27, 2026 at 02:36:19PM -0600, Keith Busch wrote:
> On Fri, Mar 27, 2026 at 03:41:50PM -0400, Benjamin Marzinski wrote:
> > > @@ -4047,9 +4047,15 @@ static void dm_integrity_io_hints(struct dm_target *ti, struct queue_limits *lim
> > >  	struct dm_integrity_c *ic = ti->private;
> > >  
> > >  	if (ic->sectors_per_block > 1) {
> > > -		limits->logical_block_size = ic->sectors_per_block << SECTOR_SHIFT;
> > > -		limits->physical_block_size = ic->sectors_per_block << SECTOR_SHIFT;
> > > -		limits->io_min = ic->sectors_per_block << SECTOR_SHIFT;
> > > +		limits->logical_block_size =
> > > +				max(limits->logical_block_size,
> > > +				    ic->sectors_per_block << SECTOR_SHIFT);
> > > +		limits->physical_block_size =
> > > +				max(limits->physical_block_size,
> > > +				    ic->sectors_per_block << SECTOR_SHIFT);
> > > +		limits->io_min =
> > > +				max(limits->io_min,
> > > +				    ic->sectors_per_block << SECTOR_SHIFT);
> > >  		limits->dma_alignment = limits->logical_block_size - 1;
> > >  		limits->discard_granularity = ic->sectors_per_block << SECTOR_SHIFT;
> > 
> > Shouldn't this also respect the underlying device's discard_granularity?
> 
> It doesn't appear to. I left it unchanged as I'm not very familiar with
> this device mapper, so that seemed safer. But I thought it was fine as
> is: this dm doesn't appear to forward discards, so the underlying
> device's constraints aren't brought into the operation. It looks like it
> just sets a "DISCARD_FILLER" pattern into metadata.

If you set allow discards, dm-intergrity should pass them down.

For example:

VALID:
# modprobe scsi_debug dev_size_mb=1024 lbpu=1
# integritysetup format -s 1024 /dev/sda
# integritysetup open --allow-discards /dev/sda integrity-test
# cat /sys/block/sda/queue/discard_granularity                  
512
# cat /sys/block/dm-1/queue/discard_granularity
1024
# blkdiscard -o 1024 -l 16384 /dev/mapper/integrity-test
# echo $?
0

perf trace:
      blkdiscard   11852 [000] 256486.743981:    block:block_bio_queue: 253,1 DS 0 + 2 [blkdiscard]
 kworker/0:1-eve   11763 [000] 256486.744063:    block:block_bio_queue: 8,0 DS 16504 + 2 [kworker/0:1]
 kworker/0:1-eve   11763 [000] 256486.744076:     block:block_rq_issue: 8,0 DS 1024 () 16504 + 2 0x2,0,4 [kworker/0:1]
         swapper       0 [000] 256486.745099:  block:block_rq_complete: 8,0 DS () 16504 + 2 0x2,0,4 [0]
         swapper       0 [000] 256486.745104: block:block_bio_complete: 253,1 DS 0 + 2 [0]


INVALID:
# modprobe scsi_debug dev_size_mb=1024 lbpu=1 sector_size=4096
# integritysetup format -s 1024 /dev/sda
# integritysetup open --allow-discards /dev/sda integrity-test
# cat /sys/block/sda/queue/discard_granularity
2048
# cat /sys/block/dm-1/queue/discard_granularity
1024
# blkdiscard -o 1024 -l 16384 /dev/mapper/integrity-test
blkdiscard: BLKDISCARD: /dev/mapper/integrity-test ioctl failed: Input/output error
# echo $?
1

perf trace:
      blkdiscard   12191 [000] 257234.995337:    block:block_bio_queue: 253,1 DS 0 + 2 [blkdiscard]
 kworker/0:1-eve   11763 [000] 257235.046620:    block:block_bio_queue: 8,0 DS 16504 + 2 [kworker/0:1]
 kworker/0:1-eve   11763 [000] 257235.046623: block:block_bio_complete: 8,0 DS 16504 + 2 [-5]
 kworker/0:1-eve   11763 [000] 257235.046629: block:block_bio_complete: 253,1 DS 0 + 2 [-5]

-Ben

Re: [PATCH 1/3] dm-integrity: fix mismatched queue limits

[Keith Busch]

On Mon, Mar 30, 2026 at 01:41:34PM -0400, Benjamin Marzinski wrote:
> INVALID:
> # modprobe scsi_debug dev_size_mb=1024 lbpu=1 sector_size=4096
> # integritysetup format -s 1024 /dev/sda
> # integritysetup open --allow-discards /dev/sda integrity-test
> # cat /sys/block/sda/queue/discard_granularity
> 2048
> # cat /sys/block/dm-1/queue/discard_granularity
> 1024
> # blkdiscard -o 1024 -l 16384 /dev/mapper/integrity-test

This patch fixes that already since it overrides the physical_block_size
to match the backing device's, and blk_validate_limits() will update
dma_granularity to be at least that size as well.

But dm-integrity probably should unconditionally set it to at least the
backing device's too, just in case the backing device wants a larger
granularity than the physical block size.