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From: Miklos Szeredi <miklos@szeredi.hu>
Date: Wed, 10 Jan 2024 16:47:23 +0100
Message-ID: <CAJfpeguE6E=s_t8WFVrJcXUar9ifr5+rhsmoJZYW5xWrTzRbMw@mail.gmail.com>
Subject: Re: [PATCH v2 09/11] fuse: file: limit splice_read to virtiofs
To: =?UTF-8?Q?Ahelenia_Ziemia=C5=84ska?= <nabijaczleweli@nabijaczleweli.xyz>
Cc: Jens Axboe <axboe@kernel.dk>, Christian Brauner <brauner@kernel.org>, 
	Alexander Viro <viro@zeniv.linux.org.uk>, linux-fsdevel@vger.kernel.org, 
	Vivek Goyal <vgoyal@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>, linux-kernel@vger.kernel.org, 
	virtualization@lists.linux.dev
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On Wed, 10 Jan 2024 at 16:19, Ahelenia Ziemia=C5=84ska
<nabijaczleweli@nabijaczleweli.xyz> wrote:

> > We need to find an alternative to refusing splice, since this is not
> > going to fly, IMO.
> The alternative is to not hold the lock. See the references in the
> cover letter for why this wasn't done. IMO a potential slight perf
> hit flies more than a total exclusion on the pipe.

IDGI.  This will make splice(2) return EINVAL for unprivileged fuse
files, right?

That would be a regression, not a perf hit, if the application is not
falling back to plain read; a reasonable scenario, considering splice
from files (including fuse) has worked on linux for a *long* time.

Thanks,
Mikos