linux-kernel - Re: [PATCH REBASE v2 0/5] return nxt propagation within io-wq ctx

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Date:   Sat, 29 Feb 2020 21:44:44 +0300
From:   Pavel Begunkov <asml.silence@...il.com>
To:     Jens Axboe <axboe@...nel.dk>, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH REBASE v2 0/5] return nxt propagation within io-wq ctx

On 29/02/2020 02:37, Pavel Begunkov wrote:
> After io_put_req_find_next() was patched, handlers no more return
> next work, but enqueue them through io_queue_async_work() (mostly
> by io_put_work() -> io_put_req()). The patchset fixes that.
> 
> Patches 1-2 clean up and removes all futile attempts to get nxt from
> the opcode handlers. The 3rd one moves all this propagation idea into
> work->put_work(). And the rest ones are small clean up on top.

And now I'm hesitant about the approach. It works fine, but I want to remove a
lot of excessive locking from io-wq, and it'll be in the way. Ignore this, I'll
try something else

The question is whether there was a problem with io_req_find_next() in the first
place... It was stealing @nxt, when it already completed a request and were
synchronous to the submission ref holder, thus it should have been fine.

> v2: rebase on top of poll changes
> 
> Pavel Begunkov (5):
>   io_uring: remove @nxt from the handlers
>   io_uring/io-wq: pass *work instead of **workptr
>   io_uring/io-wq: allow put_work return next work
>   io_uring: remove extra nxt check after punt
>   io_uring: remove io_prep_next_work()
> 
>  fs/io-wq.c    |  28 ++---
>  fs/io-wq.h    |   4 +-
>  fs/io_uring.c | 320 ++++++++++++++++++++------------------------------
>  3 files changed, 141 insertions(+), 211 deletions(-)
> 

-- 
Pavel Begunkov