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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:   Wed, 21 Jun 2023 18:40:21 +0900
From:   Keiichi Watanabe <keiichiw@...omium.org>
To:     Miklos Szeredi <miklos@...redi.hu>
Cc:     Junichi Uekawa (上川純一) 
        <uekawa@...gle.com>, 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, Jun 21, 2023 at 1:07 PM Miklos Szeredi <miklos@...redi.hu> wrote:
>
> 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.


Oh, good to know!
I could make it work in our VMM (crosvm) without any kernel changes.
https://crrev.com/c/4630879
Thanks a lot!

Keiichi


>
>
> Thanks,
> Miklos