From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: linux-nfs-owner@vger.kernel.org Received: from zeniv.linux.org.uk ([195.92.253.2]:36015 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752629Ab3AUDJp (ORCPT ); Sun, 20 Jan 2013 22:09:45 -0500 Date: Mon, 21 Jan 2013 03:09:40 +0000 From: Al Viro To: NeilBrown Cc: "Myklebust, Trond" , NFS Subject: Re: NFSv4 cannot unmount ESTALE directories (in some cases). Message-ID: <20130121030940.GS4939@ZenIV.linux.org.uk> References: <20130121134859.24fbd103@notabene.brown> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20130121134859.24fbd103@notabene.brown> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Mon, Jan 21, 2013 at 01:48:59PM +1100, NeilBrown wrote: > > If you use NFSv4 to "mount server:/foo/bar /mnt", then "rm -r" /foo/bar on the > server, then accesses to /mnt will naturally return ESTALE. > > Unfortunately "umount /mnt" will also return ESTALE and leave the stale > directory mounted. Adding "-l" or "-f" to "umount" doesn't help. > > The problem is that nfs_lookup_revalidate fails. As the mountpoint is never > not accessed by a lookup (after the initial mount) it seems a bit pointless > calling d_revalidate in this case ... by maybe not. > > I can make the problem go away by testing for LOOKUP_JUMP and having > nfs_lookup_revalidate never fail if that flag it set (for a directory). > However I cannot easily tell if this is an elegant solution of an ugly hack, The latter. Definitely. > and am hoping that someone who understands revalidation and LOOKUP_JUMPED > better than I (who only discovered the latter today) could provide advice. > > Al? Trond? Should I make this into a formal patch submission, or is there > a better way? I really suspect that mountpoint crossing on umount ought to be done differently. I'll need to play with possible variants a bit before I can offer any replacement though...