[PATCH 0/2] Fix the initialization of max_hw_wzeroes_unmap_sectors for stacking drivers

[PATCH 0/2] Fix the initialization of max_hw_wzeroes_unmap_sectors for stacking drivers

[Zhang Yi]

From: Zhang Yi <yi.zhang@huawei.com>

Hello,

This series fixes the initialization of max_hw_wzeroes_unmap_sectors in
queue_limits for all md raid and drbd drivers, preventing
blk_validate_limits() failures on underlying devices that support the
unmap write zeroes command.

Best regards,
Yi.

Zhang Yi (2):
  md: init queue_limits->max_hw_wzeroes_unmap_sectors parameter
  drbd: init queue_limits->max_hw_wzeroes_unmap_sectors parameter

 drivers/block/drbd/drbd_nl.c | 1 +
 drivers/md/md-linear.c       | 1 +
 drivers/md/raid0.c           | 1 +
 drivers/md/raid1.c           | 1 +
 drivers/md/raid10.c          | 1 +
 drivers/md/raid5.c           | 1 +
 6 files changed, 6 insertions(+)

-- 
2.46.1

[PATCH 1/2] md: init queue_limits->max_hw_wzeroes_unmap_sectors parameter

[Zhang Yi]

From: Zhang Yi <yi.zhang@huawei.com>

The parameter max_hw_wzeroes_unmap_sectors in queue_limits should be
equal to max_write_zeroes_sectors if it is set to a non-zero value.
However, the stacked md drivers call md_init_stacking_limits() to
initialize this parameter to UINT_MAX but only adjust
max_write_zeroes_sectors when setting limits. Therefore, this
discrepancy triggers a value check failure in blk_validate_limits().

Fix this failure by explicitly setting max_hw_wzeroes_unmap_sectors to
zero.

Fixes: 0c40d7cb5ef3 ("block: introduce max_{hw|user}_wzeroes_unmap_sectors to queue limits")
Reported-by: John Garry <john.g.garry@oracle.com>
Closes: https://lore.kernel.org/linux-block/803a2183-a0bb-4b7a-92f1-afc5097630d2@oracle.com/
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
---
 drivers/md/md-linear.c | 1 +
 drivers/md/raid0.c     | 1 +
 drivers/md/raid1.c     | 1 +
 drivers/md/raid10.c    | 1 +
 drivers/md/raid5.c     | 1 +
 5 files changed, 5 insertions(+)

diff --git a/drivers/md/md-linear.c b/drivers/md/md-linear.c
index 5d9b08115375..3e1f165c2d20 100644
--- a/drivers/md/md-linear.c
+++ b/drivers/md/md-linear.c
@@ -73,6 +73,7 @@ static int linear_set_limits(struct mddev *mddev)
 	md_init_stacking_limits(&lim);
 	lim.max_hw_sectors = mddev->chunk_sectors;
 	lim.max_write_zeroes_sectors = mddev->chunk_sectors;
+	lim.max_hw_wzeroes_unmap_sectors = mddev->chunk_sectors;
 	lim.io_min = mddev->chunk_sectors << 9;
 	err = mddev_stack_rdev_limits(mddev, &lim, MDDEV_STACK_INTEGRITY);
 	if (err)
diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index f1d8811a542a..419139ad7663 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -382,6 +382,7 @@ static int raid0_set_limits(struct mddev *mddev)
 	md_init_stacking_limits(&lim);
 	lim.max_hw_sectors = mddev->chunk_sectors;
 	lim.max_write_zeroes_sectors = mddev->chunk_sectors;
+	lim.max_hw_wzeroes_unmap_sectors = mddev->chunk_sectors;
 	lim.io_min = mddev->chunk_sectors << 9;
 	lim.io_opt = lim.io_min * mddev->raid_disks;
 	lim.chunk_sectors = mddev->chunk_sectors;
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 408c26398321..35c6498b4917 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -3211,6 +3211,7 @@ static int raid1_set_limits(struct mddev *mddev)
 
 	md_init_stacking_limits(&lim);
 	lim.max_write_zeroes_sectors = 0;
+	lim.max_hw_wzeroes_unmap_sectors = 0;
 	lim.features |= BLK_FEAT_ATOMIC_WRITES;
 	err = mddev_stack_rdev_limits(mddev, &lim, MDDEV_STACK_INTEGRITY);
 	if (err)
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index b60c30bfb6c7..9832eefb2f15 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -4008,6 +4008,7 @@ static int raid10_set_queue_limits(struct mddev *mddev)
 
 	md_init_stacking_limits(&lim);
 	lim.max_write_zeroes_sectors = 0;
+	lim.max_hw_wzeroes_unmap_sectors = 0;
 	lim.io_min = mddev->chunk_sectors << 9;
 	lim.chunk_sectors = mddev->chunk_sectors;
 	lim.io_opt = lim.io_min * raid10_nr_stripes(conf);
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 023649fe2476..e385ef1355e8 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -7732,6 +7732,7 @@ static int raid5_set_limits(struct mddev *mddev)
 	lim.features |= BLK_FEAT_RAID_PARTIAL_STRIPES_EXPENSIVE;
 	lim.discard_granularity = stripe;
 	lim.max_write_zeroes_sectors = 0;
+	lim.max_hw_wzeroes_unmap_sectors = 0;
 	mddev_stack_rdev_limits(mddev, &lim, 0);
 	rdev_for_each(rdev, mddev)
 		queue_limits_stack_bdev(&lim, rdev->bdev, rdev->new_data_offset,
-- 
2.46.1

[PATCH 2/2] drbd: init queue_limits->max_hw_wzeroes_unmap_sectors parameter

[Zhang Yi]

From: Zhang Yi <yi.zhang@huawei.com>

The parameter max_hw_wzeroes_unmap_sectors in queue_limits should be
equal to max_write_zeroes_sectors if it is set to a non-zero value.
However, when the backend bdev is specified, this parameter is
initialized to UINT_MAX during the call to blk_set_stacking_limits(),
while only max_write_zeroes_sectors is adjusted. Therefore, this
discrepancy triggers a value check failure in blk_validate_limits().

Since the drvd driver doesn't yet support unmap write zeroes, so fix
this failure by explicitly setting max_hw_wzeroes_unmap_sectors to
zero.

Fixes: 0c40d7cb5ef3 ("block: introduce max_{hw|user}_wzeroes_unmap_sectors to queue limits")
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
---
 drivers/block/drbd/drbd_nl.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index e09930c2b226..91f3b8afb63c 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -1330,6 +1330,7 @@ void drbd_reconsider_queue_parameters(struct drbd_device *device,
 		lim.max_write_zeroes_sectors = DRBD_MAX_BBIO_SECTORS;
 	else
 		lim.max_write_zeroes_sectors = 0;
+	lim.max_hw_wzeroes_unmap_sectors = 0;
 
 	if ((lim.discard_granularity >> SECTOR_SHIFT) >
 	    lim.max_hw_discard_sectors) {
-- 
2.46.1

Re: [PATCH 1/2] md: init queue_limits->max_hw_wzeroes_unmap_sectors parameter

[Li Nan]

在 2025/8/25 16:33, Zhang Yi 写道:
> From: Zhang Yi <yi.zhang@huawei.com>
> 
> The parameter max_hw_wzeroes_unmap_sectors in queue_limits should be
> equal to max_write_zeroes_sectors if it is set to a non-zero value.
> However, the stacked md drivers call md_init_stacking_limits() to
> initialize this parameter to UINT_MAX but only adjust
> max_write_zeroes_sectors when setting limits. Therefore, this
> discrepancy triggers a value check failure in blk_validate_limits().
> 
> Fix this failure by explicitly setting max_hw_wzeroes_unmap_sectors to
> zero.
> 
> Fixes: 0c40d7cb5ef3 ("block: introduce max_{hw|user}_wzeroes_unmap_sectors to queue limits")
> Reported-by: John Garry <john.g.garry@oracle.com>
> Closes: https://lore.kernel.org/linux-block/803a2183-a0bb-4b7a-92f1-afc5097630d2@oracle.com/
> Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
> ---
>   drivers/md/md-linear.c | 1 +
>   drivers/md/raid0.c     | 1 +
>   drivers/md/raid1.c     | 1 +
>   drivers/md/raid10.c    | 1 +
>   drivers/md/raid5.c     | 1 +
>   5 files changed, 5 insertions(+)
> 
> diff --git a/drivers/md/md-linear.c b/drivers/md/md-linear.c
> index 5d9b08115375..3e1f165c2d20 100644
> --- a/drivers/md/md-linear.c
> +++ b/drivers/md/md-linear.c
> @@ -73,6 +73,7 @@ static int linear_set_limits(struct mddev *mddev)
>   	md_init_stacking_limits(&lim);
>   	lim.max_hw_sectors = mddev->chunk_sectors;
>   	lim.max_write_zeroes_sectors = mddev->chunk_sectors;
> +	lim.max_hw_wzeroes_unmap_sectors = mddev->chunk_sectors;
>   	lim.io_min = mddev->chunk_sectors << 9;
>   	err = mddev_stack_rdev_limits(mddev, &lim, MDDEV_STACK_INTEGRITY);
>   	if (err)
> diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
> index f1d8811a542a..419139ad7663 100644
> --- a/drivers/md/raid0.c
> +++ b/drivers/md/raid0.c
> @@ -382,6 +382,7 @@ static int raid0_set_limits(struct mddev *mddev)
>   	md_init_stacking_limits(&lim);
>   	lim.max_hw_sectors = mddev->chunk_sectors;
>   	lim.max_write_zeroes_sectors = mddev->chunk_sectors;
> +	lim.max_hw_wzeroes_unmap_sectors = mddev->chunk_sectors;
>   	lim.io_min = mddev->chunk_sectors << 9;
>   	lim.io_opt = lim.io_min * mddev->raid_disks;
>   	lim.chunk_sectors = mddev->chunk_sectors;
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index 408c26398321..35c6498b4917 100644
> --- a/drivers/md/raid1.c
> +++ b/drivers/md/raid1.c
> @@ -3211,6 +3211,7 @@ static int raid1_set_limits(struct mddev *mddev)
>   
>   	md_init_stacking_limits(&lim);
>   	lim.max_write_zeroes_sectors = 0;
> +	lim.max_hw_wzeroes_unmap_sectors = 0;
>   	lim.features |= BLK_FEAT_ATOMIC_WRITES;
>   	err = mddev_stack_rdev_limits(mddev, &lim, MDDEV_STACK_INTEGRITY);
>   	if (err)
> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
> index b60c30bfb6c7..9832eefb2f15 100644
> --- a/drivers/md/raid10.c
> +++ b/drivers/md/raid10.c
> @@ -4008,6 +4008,7 @@ static int raid10_set_queue_limits(struct mddev *mddev)
>   
>   	md_init_stacking_limits(&lim);
>   	lim.max_write_zeroes_sectors = 0;
> +	lim.max_hw_wzeroes_unmap_sectors = 0;
>   	lim.io_min = mddev->chunk_sectors << 9;
>   	lim.chunk_sectors = mddev->chunk_sectors;
>   	lim.io_opt = lim.io_min * raid10_nr_stripes(conf);
> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> index 023649fe2476..e385ef1355e8 100644
> --- a/drivers/md/raid5.c
> +++ b/drivers/md/raid5.c
> @@ -7732,6 +7732,7 @@ static int raid5_set_limits(struct mddev *mddev)
>   	lim.features |= BLK_FEAT_RAID_PARTIAL_STRIPES_EXPENSIVE;
>   	lim.discard_granularity = stripe;
>   	lim.max_write_zeroes_sectors = 0;
> +	lim.max_hw_wzeroes_unmap_sectors = 0;
>   	mddev_stack_rdev_limits(mddev, &lim, 0);
>   	rdev_for_each(rdev, mddev)
>   		queue_limits_stack_bdev(&lim, rdev->bdev, rdev->new_data_offset,



LGTM, feel free to add

Reviewed-by: Li Nan <linan122@huawei.com>

-- 
Thanks,
Nan

Re: [PATCH 1/2] md: init queue_limits->max_hw_wzeroes_unmap_sectors parameter

[Paul Menzel]

Dear Yi,


Thank you for your patch.

Am 25.08.25 um 10:33 schrieb Zhang Yi:
> From: Zhang Yi <yi.zhang@huawei.com>
> 
> The parameter max_hw_wzeroes_unmap_sectors in queue_limits should be
> equal to max_write_zeroes_sectors if it is set to a non-zero value.

Excuse my ignorance, but why?

> However, the stacked md drivers call md_init_stacking_limits() to
> initialize this parameter to UINT_MAX but only adjust
> max_write_zeroes_sectors when setting limits. Therefore, this
> discrepancy triggers a value check failure in blk_validate_limits().
> 
> Fix this failure by explicitly setting max_hw_wzeroes_unmap_sectors to
> zero.

In `linear_set_limits()` and `raid0_set_limits()` you set it to 
`mddev->chunk_sectors`. Is that intentional?

> Fixes: 0c40d7cb5ef3 ("block: introduce max_{hw|user}_wzeroes_unmap_sectors to queue limits")
> Reported-by: John Garry <john.g.garry@oracle.com>
> Closes: https://lore.kernel.org/linux-block/803a2183-a0bb-4b7a-92f1-afc5097630d2@oracle.com/

It’d be great if you added the test case to the commit message.

> Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
> ---
>   drivers/md/md-linear.c | 1 +
>   drivers/md/raid0.c     | 1 +
>   drivers/md/raid1.c     | 1 +
>   drivers/md/raid10.c    | 1 +
>   drivers/md/raid5.c     | 1 +
>   5 files changed, 5 insertions(+)
> 
> diff --git a/drivers/md/md-linear.c b/drivers/md/md-linear.c
> index 5d9b08115375..3e1f165c2d20 100644
> --- a/drivers/md/md-linear.c
> +++ b/drivers/md/md-linear.c
> @@ -73,6 +73,7 @@ static int linear_set_limits(struct mddev *mddev)
>   	md_init_stacking_limits(&lim);
>   	lim.max_hw_sectors = mddev->chunk_sectors;
>   	lim.max_write_zeroes_sectors = mddev->chunk_sectors;
> +	lim.max_hw_wzeroes_unmap_sectors = mddev->chunk_sectors;
>   	lim.io_min = mddev->chunk_sectors << 9;
>   	err = mddev_stack_rdev_limits(mddev, &lim, MDDEV_STACK_INTEGRITY);
>   	if (err)
> diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
> index f1d8811a542a..419139ad7663 100644
> --- a/drivers/md/raid0.c
> +++ b/drivers/md/raid0.c
> @@ -382,6 +382,7 @@ static int raid0_set_limits(struct mddev *mddev)
>   	md_init_stacking_limits(&lim);
>   	lim.max_hw_sectors = mddev->chunk_sectors;
>   	lim.max_write_zeroes_sectors = mddev->chunk_sectors;
> +	lim.max_hw_wzeroes_unmap_sectors = mddev->chunk_sectors;
>   	lim.io_min = mddev->chunk_sectors << 9;
>   	lim.io_opt = lim.io_min * mddev->raid_disks;
>   	lim.chunk_sectors = mddev->chunk_sectors;
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index 408c26398321..35c6498b4917 100644
> --- a/drivers/md/raid1.c
> +++ b/drivers/md/raid1.c
> @@ -3211,6 +3211,7 @@ static int raid1_set_limits(struct mddev *mddev)
>   
>   	md_init_stacking_limits(&lim);
>   	lim.max_write_zeroes_sectors = 0;
> +	lim.max_hw_wzeroes_unmap_sectors = 0;
>   	lim.features |= BLK_FEAT_ATOMIC_WRITES;
>   	err = mddev_stack_rdev_limits(mddev, &lim, MDDEV_STACK_INTEGRITY);
>   	if (err)
> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
> index b60c30bfb6c7..9832eefb2f15 100644
> --- a/drivers/md/raid10.c
> +++ b/drivers/md/raid10.c
> @@ -4008,6 +4008,7 @@ static int raid10_set_queue_limits(struct mddev *mddev)
>   
>   	md_init_stacking_limits(&lim);
>   	lim.max_write_zeroes_sectors = 0;
> +	lim.max_hw_wzeroes_unmap_sectors = 0;
>   	lim.io_min = mddev->chunk_sectors << 9;
>   	lim.chunk_sectors = mddev->chunk_sectors;
>   	lim.io_opt = lim.io_min * raid10_nr_stripes(conf);
> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> index 023649fe2476..e385ef1355e8 100644
> --- a/drivers/md/raid5.c
> +++ b/drivers/md/raid5.c
> @@ -7732,6 +7732,7 @@ static int raid5_set_limits(struct mddev *mddev)
>   	lim.features |= BLK_FEAT_RAID_PARTIAL_STRIPES_EXPENSIVE;
>   	lim.discard_granularity = stripe;
>   	lim.max_write_zeroes_sectors = 0;
> +	lim.max_hw_wzeroes_unmap_sectors = 0;
>   	mddev_stack_rdev_limits(mddev, &lim, 0);
>   	rdev_for_each(rdev, mddev)
>   		queue_limits_stack_bdev(&lim, rdev->bdev, rdev->new_data_offset,

Re: [PATCH 1/2] md: init queue_limits->max_hw_wzeroes_unmap_sectors parameter

[Zhang Yi]

Hi, Paul!

On 8/25/2025 4:59 PM, Paul Menzel wrote:
> Dear Yi,
> 
> 
> Thank you for your patch.
> 
> Am 25.08.25 um 10:33 schrieb Zhang Yi:
>> From: Zhang Yi <yi.zhang@huawei.com>
>>
>> The parameter max_hw_wzeroes_unmap_sectors in queue_limits should be
>> equal to max_write_zeroes_sectors if it is set to a non-zero value.
> 
> Excuse my ignorance, but why?

Currently, the max_hw_wzeroes_unmap_sectors parameter is used only to
determine whether the backend device supports the "unmap write zeroes"
operation. If it is set to a non-zero value, it indicates that the
device supports this operation. It depends on the device supports the
write zeroes command, which means that the max_write_zeroes_sectors
should not be zero. However, we do not use this specific value, so the
max_hw_wzeroes_unmap_sectors can only have one of two values:
max_write_zeroes_sectors or 0, any other value is meaningless.

> 
>> However, the stacked md drivers call md_init_stacking_limits() to
>> initialize this parameter to UINT_MAX but only adjust
>> max_write_zeroes_sectors when setting limits. Therefore, this
>> discrepancy triggers a value check failure in blk_validate_limits().
>>
>> Fix this failure by explicitly setting max_hw_wzeroes_unmap_sectors to
>> zero.
> 
> In `linear_set_limits()` and `raid0_set_limits()` you set it to `mddev->chunk_sectors`. Is that intentional?

Yes, the linear and raid0 drivers can support unmap write zeroes
operation if all of the backend devices supports it, so we can initialize
it to chunk_sectors (the same to max_write_zeroes_sectors). raid1/10/5
drivers doesn't support write zeroes, so we have to set it to zero.

> 
>> Fixes: 0c40d7cb5ef3 ("block: introduce max_{hw|user}_wzeroes_unmap_sectors to queue limits")
>> Reported-by: John Garry <john.g.garry@oracle.com>
>> Closes: https://lore.kernel.org/linux-block/803a2183-a0bb-4b7a-92f1-afc5097630d2@oracle.com/
> 
> It’d be great if you added the test case to the commit message.

Yeah, I will add a test to blktests.

Thanks,
Yi.

> 
>> Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
>> ---
>>   drivers/md/md-linear.c | 1 +
>>   drivers/md/raid0.c     | 1 +
>>   drivers/md/raid1.c     | 1 +
>>   drivers/md/raid10.c    | 1 +
>>   drivers/md/raid5.c     | 1 +
>>   5 files changed, 5 insertions(+)
>>
>> diff --git a/drivers/md/md-linear.c b/drivers/md/md-linear.c
>> index 5d9b08115375..3e1f165c2d20 100644
>> --- a/drivers/md/md-linear.c
>> +++ b/drivers/md/md-linear.c
>> @@ -73,6 +73,7 @@ static int linear_set_limits(struct mddev *mddev)
>>       md_init_stacking_limits(&lim);
>>       lim.max_hw_sectors = mddev->chunk_sectors;
>>       lim.max_write_zeroes_sectors = mddev->chunk_sectors;
>> +    lim.max_hw_wzeroes_unmap_sectors = mddev->chunk_sectors;
>>       lim.io_min = mddev->chunk_sectors << 9;
>>       err = mddev_stack_rdev_limits(mddev, &lim, MDDEV_STACK_INTEGRITY);
>>       if (err)
>> diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
>> index f1d8811a542a..419139ad7663 100644
>> --- a/drivers/md/raid0.c
>> +++ b/drivers/md/raid0.c
>> @@ -382,6 +382,7 @@ static int raid0_set_limits(struct mddev *mddev)
>>       md_init_stacking_limits(&lim);
>>       lim.max_hw_sectors = mddev->chunk_sectors;
>>       lim.max_write_zeroes_sectors = mddev->chunk_sectors;
>> +    lim.max_hw_wzeroes_unmap_sectors = mddev->chunk_sectors;
>>       lim.io_min = mddev->chunk_sectors << 9;
>>       lim.io_opt = lim.io_min * mddev->raid_disks;
>>       lim.chunk_sectors = mddev->chunk_sectors;
>> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
>> index 408c26398321..35c6498b4917 100644
>> --- a/drivers/md/raid1.c
>> +++ b/drivers/md/raid1.c
>> @@ -3211,6 +3211,7 @@ static int raid1_set_limits(struct mddev *mddev)
>>         md_init_stacking_limits(&lim);
>>       lim.max_write_zeroes_sectors = 0;
>> +    lim.max_hw_wzeroes_unmap_sectors = 0;
>>       lim.features |= BLK_FEAT_ATOMIC_WRITES;
>>       err = mddev_stack_rdev_limits(mddev, &lim, MDDEV_STACK_INTEGRITY);
>>       if (err)
>> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
>> index b60c30bfb6c7..9832eefb2f15 100644
>> --- a/drivers/md/raid10.c
>> +++ b/drivers/md/raid10.c
>> @@ -4008,6 +4008,7 @@ static int raid10_set_queue_limits(struct mddev *mddev)
>>         md_init_stacking_limits(&lim);
>>       lim.max_write_zeroes_sectors = 0;
>> +    lim.max_hw_wzeroes_unmap_sectors = 0;
>>       lim.io_min = mddev->chunk_sectors << 9;
>>       lim.chunk_sectors = mddev->chunk_sectors;
>>       lim.io_opt = lim.io_min * raid10_nr_stripes(conf);
>> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
>> index 023649fe2476..e385ef1355e8 100644
>> --- a/drivers/md/raid5.c
>> +++ b/drivers/md/raid5.c
>> @@ -7732,6 +7732,7 @@ static int raid5_set_limits(struct mddev *mddev)
>>       lim.features |= BLK_FEAT_RAID_PARTIAL_STRIPES_EXPENSIVE;
>>       lim.discard_granularity = stripe;
>>       lim.max_write_zeroes_sectors = 0;
>> +    lim.max_hw_wzeroes_unmap_sectors = 0;
>>       mddev_stack_rdev_limits(mddev, &lim, 0);
>>       rdev_for_each(rdev, mddev)
>>           queue_limits_stack_bdev(&lim, rdev->bdev, rdev->new_data_offset,

Re: [PATCH 0/2] Fix the initialization of max_hw_wzeroes_unmap_sectors for stacking drivers

[Martin K. Petersen]

Zhang,

> This series fixes the initialization of max_hw_wzeroes_unmap_sectors
> in queue_limits for all md raid and drbd drivers, preventing
> blk_validate_limits() failures on underlying devices that support the
> unmap write zeroes command.

Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>

-- 
Martin K. Petersen

Re: [PATCH 0/2] Fix the initialization of max_hw_wzeroes_unmap_sectors for stacking drivers

[Yu Kuai]

在 2025/08/25 16:33, Zhang Yi 写道:
> From: Zhang Yi <yi.zhang@huawei.com>
> 
> Hello,
> 
> This series fixes the initialization of max_hw_wzeroes_unmap_sectors in
> queue_limits for all md raid and drbd drivers, preventing
> blk_validate_limits() failures on underlying devices that support the
> unmap write zeroes command.
> 
> Best regards,
> Yi.
> 
> Zhang Yi (2):
>    md: init queue_limits->max_hw_wzeroes_unmap_sectors parameter
>    drbd: init queue_limits->max_hw_wzeroes_unmap_sectors parameter
> 
>   drivers/block/drbd/drbd_nl.c | 1 +
>   drivers/md/md-linear.c       | 1 +
>   drivers/md/raid0.c           | 1 +
>   drivers/md/raid1.c           | 1 +
>   drivers/md/raid10.c          | 1 +
>   drivers/md/raid5.c           | 1 +
>   6 files changed, 6 insertions(+)
> 

For this set
Reviewed-by: Yu Kuai <yukuai3@huawei.com>

Thanks

Re: [PATCH 1/2] md: init queue_limits->max_hw_wzeroes_unmap_sectors parameter

[John Garry]

On 25/08/2025 09:33, Zhang Yi wrote:
> From: Zhang Yi <yi.zhang@huawei.com>
> 
> The parameter max_hw_wzeroes_unmap_sectors in queue_limits should be
> equal to max_write_zeroes_sectors if it is set to a non-zero value.
> However, the stacked md drivers call md_init_stacking_limits() to
> initialize this parameter to UINT_MAX but only adjust
> max_write_zeroes_sectors when setting limits. Therefore, this
> discrepancy triggers a value check failure in blk_validate_limits().
> 
> Fix this failure by explicitly setting max_hw_wzeroes_unmap_sectors to
> zero.
> 
> Fixes: 0c40d7cb5ef3 ("block: introduce max_{hw|user}_wzeroes_unmap_sectors to queue limits")
> Reported-by: John Garry <john.g.garry@oracle.com>
> Closes: https://lore.kernel.org/linux-block/803a2183-a0bb-4b7a-92f1-afc5097630d2@oracle.com/
> Signed-off-by: Zhang Yi <yi.zhang@huawei.com>

Tested-by: John Garry <john.g.garry@oracle.com> # raid 0/1/10

> diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
> index f1d8811a542a..419139ad7663 100644
> --- a/drivers/md/raid0.c
> +++ b/drivers/md/raid0.c
> @@ -382,6 +382,7 @@ static int raid0_set_limits(struct mddev *mddev)
>   	md_init_stacking_limits(&lim);
>   	lim.max_hw_sectors = mddev->chunk_sectors;
>   	lim.max_write_zeroes_sectors = mddev->chunk_sectors;
> +	lim.max_hw_wzeroes_unmap_sectors = mddev->chunk_sectors;
>   	lim.io_min = mddev->chunk_sectors << 9;
>   	lim.io_opt = lim.io_min * mddev->raid_disks;
>   	lim.chunk_sectors = mddev->chunk_sectors;
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index 408c26398321..35c6498b4917 100644
> --- a/drivers/md/raid1.c
> +++ b/drivers/md/raid1.c
> @@ -3211,6 +3211,7 @@ static int raid1_set_limits(struct mddev *mddev)
>   
>   	md_init_stacking_limits(&lim);
>   	lim.max_write_zeroes_sectors = 0;
> +	lim.max_hw_wzeroes_unmap_sectors = 0;

It would be better if we documented why we cannot support this on 
raid1/10, yet we can on raid0.

I am looking through the history of why max_write_zeroes_sectors is set 
to zero. I have gone as far back as 5026d7a9b, and this tells us that 
the retry mechanism for WRITE SAME causes an issue where mirrors are 
offlined (and so we disabled the support); and this was simply copied 
for write zeroes in 3deff1a70.