linux-kernel - Re: [PATCH 0/7] Permit filesystem local caching and NFS superblock sharing [try #13]

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Message-ID: <4987.1157452656@warthog.cambridge.redhat.com>
Date:	Tue, 05 Sep 2006 11:37:36 +0100
From:	David Howells <dhowells@...hat.com>
To:	Ian Kent <raven@...maw.net>
Cc:	David Howells <dhowells@...hat.com>,
	Trond Myklebust <trond.myklebust@....uio.no>,
	Andrew Morton <akpm@...l.org>, torvalds@...l.org,
	steved@...hat.com, linux-fsdevel@...r.kernel.org,
	linux-cachefs@...hat.com, nfsv4@...ux-nfs.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/7] Permit filesystem local caching and NFS superblock sharing [try #13] 

Ian Kent <raven@...maw.net> wrote:

> > As long as you don't rely on stat...mkdir working.  That can go wrong if the
> > dentry gets booted from the dcache by memory pressure in the "...".
> 
> I'm not clear on your point here.

I was wondering if you were going to rely on stat() forcing the dentry to be
correctly initialised before you did mkdir(), but it seems not.

> If I stat a path and it exists then all is good and I'm done.
> If I stat a path and I get something other than ENOENT then all is bad
> and I return fail.
> Otherwise I can just attempt to create the directory and fail if all is
> bad with that.

Okay, I suppose.  But that still doesn't seem to deal with the case of creating
a directory on the client that then overlays a symlink on the server that you
can't yet access.

You may also get ENOENT because you stat a symlink, though you'll get EEXIST
from mkdir, even if there's nothing at the far end.

David
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