Re: [PATCH v3 2/7] md/raid1: advertise atomic write limits and handle runtime constraints

[Abd-Alrhman Masalkhi <abd.masalkhi@gmail.com>]

On Thu, Jul 09, 2026 at 13:11 +0100, John Garry wrote:
> On 08/07/2026 11:13, Abd-Alrhman Masalkhi wrote:
>> Atomic writes in RAID1 must fit within a single barrier unit. Set
>> chunk_sectors to BARRIER_UNIT_SECTOR_SIZE so that bios which would cross
>> a barrier-unit boundary are rejected by the block layer before reaching
>> MD.
>
> More accurate would be to say that we restrict the atomic write limits 
> so that we never produce a write which straddles BARRIER_UNIT_SECTOR_SIZE.
>
Yes, that is more accurate. I'll update the commit message accordingly.
Thanks for the suggestion.

>> 
>> A bio that passes block-layer validation may still become unserviceable
>> within RAID1 due to bad blocks or write-behind constraints. In the former
>> case, complete the bio with EIO. In the latter case, disable
>> write-behind rather than failing the bio with EIO.
>> 
>> Fixes: f2a38abf5f1c ("md/raid1: Atomic write support")
>> Fixes: a4c55c902670 ("md/raid1: simplify raid1_write_request() error handling")
>> Signed-off-by: Abd-Alrhman Masalkhi <abd.masalkhi@gmail.com>
>
> Reviewed-by: John Garry <john.g.garry@oracle.com>
>
>

-- 
Best Regards,
Abd-Alrhman