Re: [PATCHSET 0/4] fs: Support for LOOKUP_CACHED / RESOLVE_CACHED

[Jens Axboe <axboe@kernel.dk>]

On 12/17/20 11:09 AM, Linus Torvalds wrote:
> On Thu, Dec 17, 2020 at 8:19 AM Jens Axboe <axboe@kernel.dk> wrote:
>> [..]
>> which shows a failed nonblock lookup, then punt to worker, and then we
>> complete with fd == 4. This takes 65 usec in total. Re-running the same
>> test case again:
>> [..]
>> shows the same request completing inline, also returning fd == 4. This
>> takes 6 usec.
> 
> I think this example needs to be part of the git history - either move
> it into the individual commits, or we just need to make sure it
> doesn't get lost as a cover letter and ends up part of the merge
> message.

I agree, and I think the best approach will depend a bit on whether
Al takes the core bits, and then I'm left with just the io_uring part,
or if the series goes in as a whole. In any case, I'll make sure it
gets in as either the merge message, or (at the least) in the io_uring
enablement of it.

> Despite having seen the patch series so many times now, I'm still just
> really impressed by how small and neat it is, considering the above
> numbers, and considering just how problematic this case was
> historically (ie I remember all the discussions we had about
> nonblocking opens back in the days).
> 
> So I continue to go "this is the RightWay(tm)" just from that.

Well, that's largely thanks to your and Al's feedback. I did attempt
this one time earlier, and the break through just wasn't there in
terms of condensing it properly. I'm very happy with it now.

-- 
Jens Axboe