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Subject: Re: [PATCH 0/7] Permit filesystem local caching and NFS superblock
	sharing [try #13]
From: Trond Myklebust <trond.myklebust@fys.uio.no>
To: Ian Kent <raven@themaw.net>
Cc: David Howells <dhowells@redhat.com>, Andrew Morton <akpm@osdl.org>,
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Date: Tue, 05 Sep 2006 00:17:29 -0400
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On Tue, 2006-09-05 at 12:11 +0800, Ian Kent wrote:
> On Mon, 2006-09-04 at 14:46 +0100, David Howells wrote:
> > Ian Kent <raven@themaw.net> wrote:
> > 
> > > This is the point I'm trying to make.
> > > I'm able to reproduce this with exports that don't have "nohide".
> > > The mkdir used to return EEXIST, possibly before getting to the EACCES
> > > test. It appears to be a change in semantic behavior and I can't see
> > > where it is coming from. autofs expects an EEXIST but not an EACCES and
> > > so doesn't perform the mount. I could ignore the EACCES but that would
> > > be cheating.
> > 
> > Here's something you can try:  Look in fs/nfs/dir.c.  Find nfs_lookup().  In
> > there, find the following lines:
> > 
> > 	/* If we're doing an exclusive create, optimize away the lookup */
> > 	if (nfs_is_exclusive_create(dir, nd))
> > 		goto no_entry;
> > 
> > Comment that bit out and see what the effect it.
> 
> Yes.
> 
> Commenting this out results in the expected behavior.
> No doubt this is because the following NFS lookup to the server returns
> EEXIST which is then returned to userspace.

It also breaks open(O_EXCL). Removing that is unacceptable.