Re: [PATCH v15 3/9] fuse: implement ioctls to manage backing files

From: Miklos Szeredi <miklos@szeredi.hu>
To: Jens Axboe <axboe@kernel.dk>
Cc: Amir Goldstein <amir73il@gmail.com>,
	Jingbo Xu <jefflexu@linux.alibaba.com>,
	 Bernd Schubert <bernd.schubert@fastmail.fm>,
	linux-fsdevel@vger.kernel.org,
	 Alessio Balsini <balsini@android.com>,
	Christian Brauner <brauner@kernel.org>
Subject: Re: [PATCH v15 3/9] fuse: implement ioctls to manage backing files
Date: Wed, 28 Feb 2024 16:01:17 +0100	[thread overview]
Message-ID: <CAJfpegsAs3V8jU2UWyJUB33FCbmoFiOSp9Cjzrgc9+XcomN0Uw@mail.gmail.com> (raw)
In-Reply-To: <4e3d80ad-3c61-4adf-b74f-0c62e468eb54@kernel.dk>

On Wed, 28 Feb 2024 at 15:32, Jens Axboe <axboe@kernel.dk> wrote:
>
> On 2/28/24 4:28 AM, Amir Goldstein wrote:

> > Are fixed files visible to lsof?
>
> lsof won't show them, but you can read the fdinfo of the io_uring fd to
> see them. Would probably be possible to make lsof find and show them
> too, but haven't looked into that.

Okay, that approach could be used with fuse as well.  This isn't
perfect, but we can think improving the interface for both.

> > Do they get accounted in rlimit? of which user?
>
> The fixed file table is limited in size by RLIMIT_NOFILE by the user
> that registers it.

That's different for fuse as the server wouldn't register the whole
file table in one go.  The number of used slots could be limited by
RLIMIT_NOFILE, I think.

Thanks,
Miklos