linux-kernel - Re: [V9fs-developer] [RFC] we should solve create-unlink-getattr idiom

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Message-ID: <20180209123342.11b17062@bahia.lan>
Date:   Fri, 9 Feb 2018 12:33:42 +0100
From:   Greg Kurz <groug@...d.org>
To:     jiangyiwen <jiangyiwen@...wei.com>
Cc:     Eric Van Hensbergen <ericvh@...il.com>,
        <v9fs-developer@...ts.sourceforge.net>, <qemu-devel@...gnu.org>,
        <aneesh.kumar@...ux.vnet.ibm.com>,
        Ron Minnich <rminnich@...dia.gov>,
        Latchesar Ionkov <lucho@...kov.net>,
        <linux-kernel@...r.kernel.org>, <kernel-janitors@...r.kernel.org>,
        Veaceslav Falico <veaceslav.falico@...wei.com>
Subject: Re: [V9fs-developer] [RFC] we should solve create-unlink-getattr
 idiom

On Fri, 9 Feb 2018 15:10:46 +0800
jiangyiwen <jiangyiwen@...wei.com> wrote:

> Hi Eric and Greg,
> 
> I encountered the similar problem with create-unlink-getattr idiom.
> I use the testcase that create-unlink-setattr idiom, and I see the
> bug is reported at https://bugs.launchpad.net/qemu/+bug/1336794.
> Then I also see you already fix the issue and push the patch to upstream.
> https://github.com/ericvh/linux/commit/eaf70223eac094291169f5a6de580351890162a2
> http://patchwork.ozlabs.org/patch/626194/
> 
> Unfortunately, the two patches are not merged into master, I don't know
> the reason, so I suggest if the patche can be merged into master, and
> it will solve the create-unlink-getattr idiom.
> 

I had tried to go a bit further and address the general issue of f*() syscalls
versus unlinked files:

QEMU:
http://lists.gnu.org/archive/html/qemu-devel/2016-06/msg07586.html

Linux 9p driver:
https://sourceforge.net/p/v9fs/mailman/message/35175775/

I remember that some issues were then reported during review of the
linux patches, and I never got bandwidth to investigate further...

But if you'd like to resurrect these threads, please do. :)

> Thanks,
> Yiwen
> 

Cheers,

--
Greg