linux-kernel - Re: [RFC PATCH] fuse: modification of FUSE passthrough call sequence

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Message-ID: <CAOQ4uxgCi3nB4d7dLfhFRYdvH3+MHt+xDQQRKvaBN2U5oOuX6w@mail.gmail.com>
Date: Thu, 17 Jul 2025 08:16:47 +0200
From: Amir Goldstein <amir73il@...il.com>
To: hanqi <hanqi@...o.com>
Cc: Ed.Tsai@...iatek.com, miklos@...redi.hu, linux-fsdevel@...r.kernel.org, 
	linux-kernel@...r.kernel.org, liulei.rjpt@...o.com
Subject: Re: [RFC PATCH] fuse: modification of FUSE passthrough call sequence

On Thu, Jul 17, 2025 at 4:23 AM hanqi <hanqi@...o.com> wrote:
>
>
>
> 在 2025/7/16 20:14, Amir Goldstein 写道:
> > On Wed, Jul 16, 2025 at 1:49 PM Qi Han <hanqi@...o.com> wrote:
> >> Hi, Amir
> > Hi Qi,
> >
> >> In the commit [1], performing read/write operations with DIRECT_IO on
> >> a FUSE file path does not trigger FUSE passthrough. I am unclear about
> >> the reason behind this behavior. Is it possible to modify the call
> >> sequence to support passthrough for files opened with DIRECT_IO?
> > Are you talking about files opened by user with O_DIRECT or
> > files open by server with FOPEN_DIRECT_IO?
> >
> > Those are two different things.
> > IIRC, O_DIRECT to a backing passthrough file should be possible.
>
> Hi, Amir
> Thank you for your response. I am performing read/write operations on
> a file under a FUSE path opened with O_DIRECT, using code similar to [1].
> However, it seems that the FUSE daemon adds FOPEN_DIRECT_IO, as Ed
> mentioned. I need to further investigate the FUSE daemon code to confirm
> the reason behind this behavior.
>
> [1]
> fd_in = open(src_path, O_RDONLY | O_DIRECT);
> fd_out = open(dst_path, O_WRONLY | O_CREAT | O_TRUNC | O_DIRECT, 0644);
>

Seems like the server should be fixed.

Thanks,
Amir.