Re: blk-mq flush fix

From: Christoph Hellwig
Date: Mon Oct 28 2013 - 04:48:30 EST


On Sun, Oct 27, 2013 at 10:29:25PM +0000, Jens Axboe wrote:
> On Sat, Oct 26 2013, Christoph Hellwig wrote:
> > I think this variant of the patch from Alexander should fix the issue
> > in a minimally invasive way. Longer term I'd prefer to use q->flush_rq
> > like in the non-mq case by copying over the context and tag information.
>
> This one is pretty simple, we could definitely use it as a band aid. I
> too would greatly prefer using the static ->flush_rq instead. Just have
> it marked to bypass most of the free logic.

We already bypass the free logical by setting and end_io callback for
a while, similar to what the old code does. Maybe it's not all that
hard to prealloc the request, let me give a sping. Using the static
allocated one will be hard due to the driver-specific extra data,
though.

> I'll add this one.

Gimme another day or so to figure this out.
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