[PATCH 04/14] block: use queue_limits_commit_update in queue_max_sectors_store

[Christoph Hellwig]

On Tue, Jan 30, 2024 at 12:14:32PM +0000, John Garry wrote:
> On 28/01/2024 16:58, Christoph Hellwig wrote:
>> Convert queue_max_sectors_store to use queue_limits_commit_update to
>> check and update the max_sectors limit and freeze the queue before
>> doing so to ensure we don't have requests in flight while changing
>> the limits.
>>
>> Note that this removes the previously held queue_lock that doesn't
>> protect against any other reader or writer.
>
> I don't really get why we specifically locked that code segment in 
> queue_max_sectors_store() previously. Was it to ensure max_sectors and 
> q->disk->bdi->io_pages are always atomically updated?

It's been there basically forever.  Back in the day before blk-mq
and lock splitting it might actually have protected something.