Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
To:     Pavel Begunkov <asml.silence@gmail.com>,
        Jens Axboe <axboe@kernel.dk>, io-uring@vger.kernel.org,
        Josh Triplett <josh@joshtriplett.org>
Cc:     "David S . Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org
References: <cover.1628871893.git.asml.silence@gmail.com>
From:   Stefan Metzmacher <metze@samba.org>
Subject: Re: [PATCH v2 0/4] open/accept directly into io_uring fixed file
 table
Message-ID: <17841c48-093e-af1c-c7c9-aa00859eb1b9@samba.org>
Date:   Mon, 16 Aug 2021 17:45:36 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.11.0
MIME-Version: 1.0
In-Reply-To: <cover.1628871893.git.asml.silence@gmail.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Precedence: bulk

Hi Pavel,

> The behaviour is controlled by setting sqe->file_index, where 0 implies
> the old behaviour. If non-zero value is specified, then it will behave
> as described and place the file into a fixed file slot
> sqe->file_index - 1. A file table should be already created, the slot
> should be valid and empty, otherwise the operation will fail.
> 
> Note 1: we can't use IOSQE_FIXED_FILE to switch between modes, because
> accept takes a file, and it already uses the flag with a different
> meaning.

Would it be hard to support IOSQE_FIXED_FILE for the dirfd of openat*, renameat, unlinkat, statx?
(And mkdirat, linkat, symlinkat when they arrive)
renameat and linkat might be trickier as they take two dirfds, but it
would make the feature more complete and useful.

metze