Re: [patch]blk-mq: blk_mq_tag_to_rq should handle flush request

[Jens Axboe]

On 2014-05-09 22:00, Shaohua Li wrote:
> On Fri, May 09, 2014 at 08:00:18AM -0700, Christoph Hellwig wrote:
> > On Fri, May 09, 2014 at 08:07:33PM +0800, Shaohua Li wrote:
> > > flush request is special, which borrows tag from other request. Need a special
> > > handling to get it from tag.
> >
> > Thanks, we probably need this one.  But I think you can simply test
> > REQ_FLUSH_SEQ the passed in request instead of the flush_rq_tag_valid
> > flag/
>
> fair enough. updated one.
>
>
> Subject: blk-mq: blk_mq_tag_to_rq should handle flush request
>
> flush request is special, which borrows tag from other request. Need a special
> handling to get it from tag.

I have applied this one, but it irks me a little bit since we have to 
touch q->flush_rq->stuff from a potential hot path. I haven't thought 
much about this yet, but it would be a lot better if we could fold in 
the flush tag somehow.

--
Jens Axboe

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