linux-kernel - Re: [PATCH] md/md-linear: Enable atomic writes

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Message-ID: <557f39a4-a760-4b10-80e3-229f7a4892cb@oracle.com>
Date: Tue, 23 Sep 2025 09:21:15 +0100
From: John Garry <john.g.garry@...cle.com>
To: Yu Kuai <yukuai1@...weicloud.com>, song@...nel.org
Cc: linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org,
        martin.petersen@...cle.com, "yukuai (C)" <yukuai3@...wei.com>
Subject: Re: [PATCH] md/md-linear: Enable atomic writes

On 05/09/2025 10:02, Yu Kuai wrote:
> 在 2025/09/04 0:10, John Garry 写道:
>> All the infrastructure has already been plumbed to support this for
>> stacked devices, so just enable the request_queue limits features flag.
>>
>> A note about chunk sectors for linear arrays:
>> While it is possible to set a chunk sectors param for building a linear
>> array, this is for specifying the granularity at which data sectors from
>> the device are used. It is not the same as a stripe size, like for RAID0.
>>
>> As such, it is not appropriate to set chunk_sectors request queue 
>> limit to
>> the same value, as chunk_sectors request limit is a boundary for which
>> requests cannot straddle.
>>
>> However, request_queue limit max_hw_sectors is set to chunk sectors, 
>> which
>> almost has the same effect as setting chunk_sectors limit.
>>
>> Signed-off-by: John Garry <john.g.garry@...cle.com>
>>
>> diff --git a/drivers/md/md-linear.c b/drivers/md/md-linear.c
>> index 5d9b081153757..30ac29b990c9b 100644
>> --- a/drivers/md/md-linear.c
>> +++ b/drivers/md/md-linear.c
>> @@ -74,6 +74,7 @@ static int linear_set_limits(struct mddev *mddev)
>>       lim.max_hw_sectors = mddev->chunk_sectors;
>>       lim.max_write_zeroes_sectors = mddev->chunk_sectors;
>>       lim.io_min = mddev->chunk_sectors << 9;
>> +    lim.features |= BLK_FEAT_ATOMIC_WRITES;
>>       err = mddev_stack_rdev_limits(mddev, &lim, MDDEV_STACK_INTEGRITY);
>>       if (err)
>>           return err;
>>
> 
> LGRM
> Reviewed-by: Yu Kuai <yukuai3@...wei.com>
> 

thanks

Could I have this picked up now? Maybe it was missed.