linux-kernel - Re: Re: [PATCH RFC v2 0/2] fuse: compound commands

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Message-ID: <aVON2GgM7KK4oBb_@fedora.fritz.box>
Date: Tue, 30 Dec 2025 09:36:45 +0100
From: Horst Birthelmer <horst@...thelmer.de>
To: Jingbo Xu <jefflexu@...ux.alibaba.com>
Cc: Horst Birthelmer <hbirthelmer@...glemail.com>, 
	Miklos Szeredi <miklos@...redi.hu>, Bernd Schubert <bschubert@....com>, linux-kernel@...r.kernel.org, 
	linux-fsdevel@...r.kernel.org, Horst Birthelmer <hbirthelmer@....com>, 
	syzbot@...kaller.appspotmail.com
Subject: Re: Re: [PATCH RFC v2 0/2] fuse: compound commands

On Mon, Dec 29, 2025 at 02:03:02PM +0800, Jingbo Xu wrote:
> Hi Horst & Bernd,
> 
> On 12/24/25 6:13 AM, Horst Birthelmer wrote:
> > In the discussion about open+getattr here [1] Bernd and Miklos talked
> > about the need for a compound command in fuse that could send multiple
> > commands to a fuse server.
> >     
> > Here's a propsal for exactly that compound command with an example
> > (the mentioned open+getattr).
> >     
> > [1] https://lore.kernel.org/linux-fsdevel/CAJfpegshcrjXJ0USZ8RRdBy=e0MxmBTJSCE0xnxG8LXgXy-xuQ@mail.gmail.com/
> > 
> 
> To achieve close-to-open, why not just invalidate the cached attr on
> open so that the following access to the attr would trigger a new
> FUSE_GETATTR request to fetch the latest attr from server?
> 

Hi Jingbo,

you are probably right, that it can be achieved that way. I thas some consequences that can be avoided, like having to wait at a later moment for the attributes to be fetched.

The main goal of this patch however was not close-to-open, even though it was discussed in that context.

We can do a lot more with the compounds than just fix close-to-open consistency. As Bernd mentioned, I am very close to havin implemented the fuse_atomic_open() call with compounds, namely the atomic combination of lookup+create.
And there are some more ideas out there.

open+getattr was just the low hanging fruit in this case.

Cheers,
Horst