Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756262AbZFHWoN (ORCPT ); Mon, 8 Jun 2009 18:44:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752633AbZFHWoA (ORCPT ); Mon, 8 Jun 2009 18:44:00 -0400 Received: from sith.mimuw.edu.pl ([193.0.96.4]:38503 "EHLO sith.mimuw.edu.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752484AbZFHWn7 (ORCPT ); Mon, 8 Jun 2009 18:43:59 -0400 Date: Tue, 9 Jun 2009 00:44:06 +0200 From: Jan Rekorajski To: Valerie Aurora Cc: Jan Blunck , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, viro@zeniv.linux.org.uk, bharata@in.ibm.com, dwmw2@infradead.org, mszeredi@suse.cz Subject: Re: [PATCH 00/32] VFS based Union Mount (V3) Message-ID: <20090608224406.GA6801@sith.mimuw.edu.pl> Mail-Followup-To: Jan Rekorajski , Valerie Aurora , Jan Blunck , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, viro@zeniv.linux.org.uk, bharata@in.ibm.com, dwmw2@infradead.org, mszeredi@suse.cz References: <1242662968-11684-1-git-send-email-jblunck@suse.de> <20090521125419.GM30663@sith.mimuw.edu.pl> <20090608195752.GD4363@fsbox> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090608195752.GD4363@fsbox> X-Operating-System: Linux 2.6.29.4 x86_64 User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2255 Lines: 59 On Mon, 08 Jun 2009, Valerie Aurora wrote: > On Thu, May 21, 2009 at 02:54:19PM +0200, Jan Rekorajski wrote: > > On Mon, 18 May 2009, Jan Blunck wrote: > > > > > Here is another post of the VFS based union mount implementation. > > > > Is there any chance this will support NFS? I can union-mount tmpfs over > > NFS as the read-only layer ought to work. NFS as the read-write layer > is still up in the air. As I don't need rw NFS, i didn't even try that :) > > nfs mounted fs, but if I try to mount --union two NFS filesystems I > > always get -EBUSY on second mount on the same mountpoint. > > > > Something along these lines: > > > > doesn't matter if I use --union on first mount, the result is always the > > same. > > > > mount <--union> -t nfs server:/export/system /mnt > > OK > > mount --union -t nfs server:/export/profile /mnt > > mount.nfs: /mnt is busy or already mounted > > > > I patched mount.nfs so it knows about MS_UNION, and strace shows me that > > it passes that flag to kernel. > > FYI, using --union on the first mount will make it union with the > local directory below it. The --union option is not needed when you > mount the lower read-only layer. Thanks for clarification. > You'll get -EBUSY on the second mount of any NFS file system over > another - try it again with the --union flag. Support for NFS on NFS > union mount would have to change this. I did just that, --union didn't change standard NFS behaviour. mount -t nfs server:/export/system /mnt mount --union -t nfs server:/export/profile /mnt mount.nfs: /mnt is busy or already mounted I did an experiment by using different IP of the server (same machine) when mounting the second fs, mount worked then, but 'ls -1 /mnt' oopsed. I can reproduce this and send you the oops next week. -- Jan Rekorajski | ALL SUSPECTS ARE GUILTY. PERIOD! bagginsmimuw.edu.pl | OTHERWISE THEY WOULDN'T BE SUSPECTS, WOULD THEY? BOFH, MANIAC | -- TROOPS by Kevin Rubio -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/