linux-kernel - Re: [PATCH RFC 2/2] io_uring: add support for getdents

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Message-ID: <20230430231528.GB2155823@dread.disaster.area>
Date:   Mon, 1 May 2023 09:15:28 +1000
From:   Dave Chinner <david@...morbit.com>
To:     Dominique Martinet <asmadeus@...ewreck.org>
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        Christian Brauner <brauner@...nel.org>,
        Jens Axboe <axboe@...nel.dk>,
        Pavel Begunkov <asml.silence@...il.com>,
        Stefan Roesch <shr@...com>, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, io-uring@...r.kernel.org
Subject: Re: [PATCH RFC 2/2] io_uring: add support for getdents

On Fri, Apr 28, 2023 at 08:27:53PM +0900, Dominique Martinet wrote:
> Dominique Martinet wrote on Fri, Apr 28, 2023 at 03:14:52PM +0900:
> > > We already pass a struct dir_context to ->iterate_shared(), so we
> > > have a simple way to add context specific flags down the filesystem
> > > from iterate_dir(). This is similar to the iocb for file data IO
> > > that contains the flags field that holds the IOCB_NOWAIT context for
> > > io_uring based IO. So the infrastructure to plumb it all the way
> > > down the fs implementation of ->iterate_shared is already there.
> > 
> > Sure, that sounds like a good approach that isn't breaking the API (not
> > breaking iterate/iterate_shared implementations that don't look at the
> > flags and allowing the fs that want to look at it to do so)
> 
> Hmm actually I said that, but io_getdents() needs to know if the flag
> will be honored or not (if it will be honored, we can call this when
> issue_flags & IO_URING_F_NONBLOCK but if we're not sure the fs handles
> it then we risk blocking)

See the new FMODE_DIO_PARALLEL_WRITE flag for triggering filesystem
specific non-blocking io_uring behaviour....

-Dave.
-- 
Dave Chinner
david@...morbit.com