From: Trond Myklebust <trond.myklebust@fys.uio.no>
Subject: Re: Marking inodes as stale can be wrong
Date: Thu, 29 Apr 2004 13:09:30 -0400
Sender: nfs-admin@lists.sourceforge.net
Message-ID: <1083258570.3686.38.camel@lade.trondhjem.org>
References: <20040429144012.GA15361@suse.de>
	 <1083257096.3686.27.camel@lade.trondhjem.org>
	 <20040429165802.GA18748@suse.de>
Mime-Version: 1.0
Content-Type: text/plain
Cc: nfs@lists.sourceforge.net
To: Olaf Kirch <okir@suse.de>
In-Reply-To: <20040429165802.GA18748@suse.de>
Errors-To: nfs-admin@lists.sourceforge.net

On Thu, 2004-04-29 at 12:58, Olaf Kirch wrote:
> On Thu, Apr 29, 2004 at 12:44:56PM -0400, Trond Myklebust wrote:
> > On Thu, 2004-04-29 at 10:40, Olaf Kirch wrote:
> > > 	fh_verify did the subtree check, and found that
> > > 	~/Mail was mode 700, and hence user nobody didn't
> > > 	have x permissions on the directory. So it would
> > > 	return ESTALE to the client.
> > 
> > This is a bug!
> 
> Yes, probably. Even though I'm not entirely sure NFSERR_ACCES is a valid
> return for all NFS operations.

The problem is that Neil is using NFSERR_STALE as a standin for
NFSERR_ACCES precisely because the latter is not on the list of accepted
return value for GETATTR in RFC1813.
IMO this is *worse* behaviour than just returning the non-rfc compatible
error.

> However, machines with 2.4 will be out there for a while, so the question
> I'm asking myself is how to cope with those in the client.

I am totally uninterested in fixing up a broken server option (even if
it is a default option) inside the client. These "fixes" have a tendency
to persist for way too long in the kernel code, and end up causing way
more problems in the long run.

"subtree_check" has a number of other RFC-violating bugs (most notably
with cross-directory renames) that mean we should *never* have made it a
default option in the first place.
The correct workaround here is to advise people to *always* use
"no_subtree_check" and then to look into fixing these problems in future
revisions of the server, not the client.

Cheers,
  Trond


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