don't reorder requests passed to ->queue_rqs

[Christoph Hellwig]

On Wed, Nov 13, 2024 at 01:51:48PM -0700, Jens Axboe wrote:
> Thanks for testing, but you can't verify any kind of perf change with
> that kind of setup. I'll be willing to bet that it'll be 1-2% drop at
> higher rates, which is substantial. But the reordering is a problem, not
> just for zoned devices, which is why I chose to merge this.

So I did not see any variation, but I also don't have access to a really
beefy setup right now.  If there is a degradation it probably is that
touching rq_next for each request actually has an effect if the list is
big enough and they aren't cache hot any more.  I can cook up a patch
that goes back to the scheme currently used upstream in nvme and virtio
that just cuts of the list at a hctx change instead of moving the
requests one by one now that the block layer doesn't mess up the order.