linux-kernel - Re: [PATCH RFC] vfs: make fstatat retry on ESTALE errors from getattr call

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Date:	Tue, 17 Apr 2012 14:04:34 +0000
From:	"Myklebust, Trond" <Trond.Myklebust@...app.com>
To:	Jeff Layton <jlayton@...hat.com>
CC:	Miklos Szeredi <miklos@...redi.hu>,
	Bernd Schubert <bernd.schubert@...m.fraunhofer.de>,
	Malahal Naineni <malahal@...ibm.com>,
	"linux-nfs@...r.kernel.org" <linux-nfs@...r.kernel.org>,
	"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"pstaubach@...grid.com" <pstaubach@...grid.com>,
	"viro@...IV.linux.org.uk" <viro@...IV.linux.org.uk>,
	"hch@...radead.org" <hch@...radead.org>,
	"michael.brantley@...haw.com" <michael.brantley@...haw.com>,
	"sven.breuner@...m.fraunhofer.de" <sven.breuner@...m.fraunhofer.de>
Subject: Re: [PATCH RFC] vfs: make fstatat retry on ESTALE errors from
 getattr call

On Tue, 2012-04-17 at 09:32 -0400, Jeff Layton wrote:
> On Tue, 17 Apr 2012 15:12:20 +0200
> Miklos Szeredi <miklos@...redi.hu> wrote:

> To do that would require protocol support that we simply don't have. We
> don't have a way to (for instance) say via NFS "give me the attributes
> for this filename". Well, at least not for NFSv3...

What's wrong with LOOKUP?

> With v4 you could theoretically construct a compound that does that,
> but you'd have to assume that the server won't release the reference to
> the inode midway through the compound. That's a reasonably safe
> assumption.

Actually, NFSv4 is the one that has the problem: there are no atomicity
guarantees within compounds, so you could theoretically get an ESTALE in
the GETATTR part of our lookup compound.

-- 
Trond Myklebust
Linux NFS client maintainer

NetApp
Trond.Myklebust@...app.com
www.netapp.com