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From:   Miklos Szeredi <miklos@szeredi.hu>
Date:   Wed, 21 Jun 2023 06:07:30 +0200
Message-ID: <CAJfpegtNjAELur_AtqiGdO6LJRDyT+WQ1UKtG-o=Em0rAhOKMg@mail.gmail.com>
Subject: Re: [PATCH 2/3] fuse: Add negative_dentry_timeout option
To:     =?UTF-8?B?SnVuaWNoaSBVZWthd2EgKOS4iuW3nee0lOS4gCk=?= 
        <uekawa@google.com>
Cc:     Keiichi Watanabe <keiichiw@chromium.org>,
        LKML <linux-kernel@vger.kernel.org>, mhiramat@google.com,
        takayas@chromium.org, drosen@google.com, sarthakkukreti@google.com,
        Jonathan Corbet <corbet@lwn.net>, linux-doc@vger.kernel.org,
        linux-fsdevel@vger.kernel.org
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On Wed, 21 Jun 2023 at 00:53, Junichi Uekawa (=E4=B8=8A=E5=B7=9D=E7=B4=94=
=E4=B8=80) <uekawa@google.com> wrote:
>
> Hi
>
>
>
> 2023=E5=B9=B46=E6=9C=8821=E6=97=A5(=E6=B0=B4) 4:28 Miklos Szeredi <miklos=
@szeredi.hu>:
>>
>> On Tue, 20 Jun 2023 at 17:14, Keiichi Watanabe <keiichiw@chromium.org> w=
rote:
>> >
>> > 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=3D0 er=
r=3D0 (instead of ENOENT) with e.entry_timeout=3Dnegative_timeout,
> for each lookup (and there's no global configuration but that's okay) ?

Yes.

Thanks,
Miklos