From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754990Ab2IYKnF (ORCPT ); Tue, 25 Sep 2012 06:43:05 -0400 Received: from out03.mta.xmission.com ([166.70.13.233]:57820 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754009Ab2IYKnC (ORCPT ); Tue, 25 Sep 2012 06:43:02 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: Maarten Lankhorst Cc: al viro , linux-fsdevel@vger.kernel.org, LKML References: <50609C43.1070702@canonical.com> <87txumrct6.fsf@xmission.com> <50615268.1040805@canonical.com> <8db34325-e8e4-4e24-85dd-c8951769e2b6@email.android.com> <506173A6.2050705@canonical.com> Date: Tue, 25 Sep 2012 03:42:50 -0700 In-Reply-To: <506173A6.2050705@canonical.com> (Maarten Lankhorst's message of "Tue, 25 Sep 2012 11:04:38 +0200") Message-ID: <87ipb2pemt.fsf@xmission.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=;;;mid=;;;hst=in01.mta.xmission.com;;;ip=98.207.153.68;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1/WJ+eHFOhvDQzUZ3093IHkJGj9a3S3yec= X-SA-Exim-Connect-IP: 98.207.153.68 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.1 XMSubLong Long Subject * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -3.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0033] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa01 1397; Body=1 Fuz1=1 Fuz2=1] * 0.0 T_TooManySym_01 4+ unique symbols in subject * 0.0 T_TooManySym_02 5+ unique symbols in subject X-Spam-DCC: XMission; sa01 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Maarten Lankhorst X-Spam-Relay-Country: Subject: Re: [PATCH] Revert "__d_unalias() should refuse to move mountpoints" X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Fri, 06 Aug 2010 16:31:04 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Maarten Lankhorst writes: > 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) Modern NFS does some interesting things with disconnected roots and the like. I don't think it should be connecting those two filesytems together because there are no overlapping directories. I really don't get why using one filesystem causes confusion in the other. > 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 Could you try the following patch? This should report what directories cannot be renamed because one of them is a mount point and it gives some real insight into what is going on. Eric diff --git a/fs/dcache.c b/fs/dcache.c index 8086636..193b7be 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -2374,6 +2374,7 @@ struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2) return NULL; } +static char *__dentry_path(struct dentry *dentry, char *buf, int buflen); /* * This helper attempts to cope with remotely renamed directories * @@ -2401,6 +2402,18 @@ static struct dentry *__d_unalias(struct inode *inode, goto out_err; m2 = &alias->d_parent->d_inode->i_mutex; out_unalias: +#if 1 + if (d_mountpoint(alias)) { + static char buf1[8192]; + static char buf2[8192]; + char *alias_name, *dentry_name; + alias_name = __dentry_path(alias, buf1, sizeof(buf1)); + dentry_name = __dentry_path(dentry, buf2, sizeof(buf2)); + + printk(KERN_DEBUG "%s: %s -> %s\n", + __func__, alias_name, dentry_name); + } +#endif if (likely(!d_mountpoint(alias))) { __d_move(alias, dentry); ret = alias;