From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754120Ab2IYJEo (ORCPT ); Tue, 25 Sep 2012 05:04:44 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:38619 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750847Ab2IYJEm (ORCPT ); Tue, 25 Sep 2012 05:04:42 -0400 Message-ID: <506173A6.2050705@canonical.com> Date: Tue, 25 Sep 2012 11:04:38 +0200 From: Maarten Lankhorst User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120827 Thunderbird/15.0 MIME-Version: 1.0 To: "Eric W. Biederman" CC: al viro , linux-fsdevel@vger.kernel.org, LKML Subject: Re: [PATCH] Revert "__d_unalias() should refuse to move mountpoints" References: <50609C43.1070702@canonical.com> <87txumrct6.fsf@xmission.com> <50615268.1040805@canonical.com> <8db34325-e8e4-4e24-85dd-c8951769e2b6@email.android.com> In-Reply-To: <8db34325-e8e4-4e24-85dd-c8951769e2b6@email.android.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hey, Op 25-09-12 09:05, Eric W. Biederman schreef: > Maarten Lankhorst wrote: > >> Hey, >> >> Op 25-09-12 05:39, Eric W. Biederman schreef: >>> Maarten Lankhorst writes: >>> >>>> This reverts commit ee3efa91e240f513898050ef305a49a653c8ed90. >>>> >>>> Signed-off-by: Maarten Lankhorst >>>> >>>> My thread about the regression seemed to have been ignored, so I can >> only >>>> conclude nobody objects against a full revert of this patch. >>>> >>>> My testcase is simply booting through netboot with / and ~/nfs as >> separate >>>> nfs filesystems, then doing 'ls ~/nfs' followed by 'ls ~' in a >> gnome-terminal >>>> window, then I get: >>> Do I read your description correctly: Without using a bind mount you >>> have the same nfs filesystem mounted on / and on ~/nfs? >>> >>> Something is definitely off with your configuration but if to work >> you >>> need to move mount points around then that something seems much >> deeper >>> than the __d_unalias change. >>> >>> What filesystems do you have mounted where? >>> >> / is a nfs filesystem, ~/nfs is a different nfs filesystem. > Are both filesystems on the same server? > > Are the two filesystems distinct filesystem on the server? > > Unless there is duplication of something somewhere the d_unalias code should not trigger. They're both on the same physical filesystem on the server, but unique exports: /home/mlankhorst/nfs *(no_subtree_check,insecure,rw,all_squash,anonuid=1000,anongid=1000) /home/mlankhorst/kvm/quantal-amd64 *(no_subtree_check,insecure,rw,no_root_squash) Rootfs is mounted by the kernel itself, I used a custom init script to mount /lib/modules early on: mount -t nfs -o nolock,vers=3 192.168.1.128:/home/mlankhorst/nfs /home/mlankhorst/nfs && mkdir -p /lib/modules/$(uname -r)/kernel && mount --bind /home/mlankhorst/nfs/linux /lib/modules/$(uname -r)/kernel && ([ -f /lib/modules/$(uname -r)/modules.symbols ] || depmod) exec /sbin/init >> Just doing >> ls / is enough >> to make all filesystems mounted on / return -EBUSY and disappear. >> >> I also have a subdir of ~/nfs/ bind mounted to /lib/modules/$(uname >> -r)/kernel >> for easy debugging so just doing 'make' in the kernel tree is enough to >> get the >> new modules + bzImage, but I don't know if it is a factor in >> reproducing this bug >> or not. > Unlikely. But interesting. It at least fits the criteria of showing up to different places. It should not be enough for d_materialise uniqe. > Either way until the root cause is found could this patch be reverted? ~Maarten