Re: lk 3.17-rc4 blk_mq large write problems

[Christoph Hellwig <hch@infradead.org>]

On Wed, Sep 10, 2014 at 12:26:57PM -0600, Jens Axboe wrote:
> > I have to.  It's set by start_request, so we need to pass down the last
> > argument to keep the old behavior.  And once we pass the argument we
> > can just it directly.
> 
> It could still be done in the caller, but arguably, you'd have to do it
> twice unless the ->queue_rq() call was rolled into a function.

At which point we'd better do it the right way and just pass the flag
instead of wasting a request flag for it.  The other benefit is that
there is a clear compile time API break for ->queue_rq that reminds
people that need to start using blk_mq_start_request.

Anyway, still waiting for test reports of the people that can reproduce
the timeouts.  By the time I'll submit the patch it should have a much
better changelog.