linux-kernel - Re: [PATCH 2/3] fuse: Add negative_dentry

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Message-ID: <CAJfpegtNjAELur_AtqiGdO6LJRDyT+WQ1UKtG-o=Em0rAhOKMg@mail.gmail.com>
Date:   Wed, 21 Jun 2023 06:07:30 +0200
From:   Miklos Szeredi <miklos@...redi.hu>
To:     Junichi Uekawa (上川純一) 
        <uekawa@...gle.com>
Cc:     Keiichi Watanabe <keiichiw@...omium.org>,
        LKML <linux-kernel@...r.kernel.org>, mhiramat@...gle.com,
        takayas@...omium.org, drosen@...gle.com, sarthakkukreti@...gle.com,
        Jonathan Corbet <corbet@....net>, linux-doc@...r.kernel.org,
        linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH 2/3] fuse: Add negative_dentry_timeout option

On Wed, 21 Jun 2023 at 00:53, Junichi Uekawa (上川純一) <uekawa@...gle.com> wrote:
>
> Hi
>
>
>
> 2023年6月21日(水) 4:28 Miklos Szeredi <miklos@...redi.hu>:
>>
>> On Tue, 20 Jun 2023 at 17:14, Keiichi Watanabe <keiichiw@...omium.org> wrote:
>> >
>> > Add `negative_dentry_timeout` mount option for FUSE to cache negative
>> > dentries for the specified duration.
>>
>> This is already possible, no kernel changes needed.  See e.g.
>> xmp_init() in libfuse/example/passthrough.c.
>>
>
> Thank you for the pointer!
>
> So reading libfuse/fuse.c, fuse_lib_lookup does a reply with e.ino=0 err=0 (instead of ENOENT) with e.entry_timeout=negative_timeout,
> for each lookup (and there's no global configuration but that's okay) ?

Yes.

Thanks,
Miklos