From owner-freebsd-fs@FreeBSD.ORG Fri Jul 15 10:27:14 2011 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id E7888106566C for ; Fri, 15 Jul 2011 10:27:13 +0000 (UTC) (envelope-from Martin.Birgmeier@aon.at) Received: from email.aon.at (nat-warsl417-01.aon.at [195.3.96.119]) by mx1.freebsd.org (Postfix) with ESMTP id 3123F8FC0A for ; Fri, 15 Jul 2011 10:27:12 +0000 (UTC) Received: (qmail 15662 invoked from network); 15 Jul 2011 10:27:11 -0000 Received: from smarthub96.highway.telekom.at (HELO email.aon.at) ([172.18.5.235]) (envelope-sender ) by fallback43.highway.telekom.at (qmail-ldap-1.03) with SMTP for ; 15 Jul 2011 10:27:11 -0000 Received: (qmail 26343 invoked from network); 15 Jul 2011 10:27:08 -0000 X-Spam-Checker-Version: SpamAssassin 3.2.0 (2007-05-01) on WARSBL603.highway.telekom.at X-Spam-Level: Received: from 188-23-47-138.adsl.highway.telekom.at (HELO gandalf.xyzzy) ([188.23.47.138]) (envelope-sender ) by smarthub96.highway.telekom.at (qmail-ldap-1.03) with SMTP for ; 15 Jul 2011 10:27:08 -0000 Received: from atpcdvvc.xyzzy (atpcdvvc.xyzzy [IPv6:fec0:0:0:4d42::84]) by gandalf.xyzzy (8.14.4/8.14.4) with ESMTP id p6FAR8ME009261 for ; Fri, 15 Jul 2011 12:27:08 +0200 (CEST) (envelope-from Martin.Birgmeier@aon.at) Message-ID: <4E2015FC.8020906@aon.at> Date: Fri, 15 Jul 2011 12:27:08 +0200 From: Martin Birgmeier User-Agent: Mozilla/5.0 (X11; FreeBSD i386; rv:5.0) Gecko/20110708 Thunderbird/5.0 MIME-Version: 1.0 To: freebsd-fs@freebsd.org References: <201107081310.p68DA3Nj019275@freefall.freebsd.org> <20110715101308.GB87688@pm513-1.comsys.ntu-kpi.kiev.ua> In-Reply-To: <20110715101308.GB87688@pm513-1.comsys.ntu-kpi.kiev.ua> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: kern/131342: [nfs] mounting/unmounting of disks causes NFS to fail X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 15 Jul 2011 10:27:14 -0000 I do not think what you write has to do with the error condition I describe, for two reasons: first, mountd is only consulted while doing mounts, and the client is not doing a mount, but rather only a file access on an already mounted file system; and second, this happens when I mount a file system on the server which is not exported and thus does not cause the exports list to be changed. Regards, Martin On 07/15/11 12:13, Andrey Simonenko wrote: > On Fri, Jul 08, 2011 at 01:10:03PM +0000, Martin Birgmeier wrote: >> The following reply was made to PR kern/131342; it has been noted by GNATS. >> >> From: Martin Birgmeier >> To: bug-followup@FreeBSD.org >> Cc: >> Subject: Re: kern/131342: [nfs] mounting/unmounting of disks causes NFS to >> fail >> Date: Fri, 08 Jul 2011 15:00:03 +0200 >> >> This is a friendly reminder that some kind soul with knowledge of the >> relevant kernel parts look into this... the error can easily be >> reproduced. I just had it on a 7.4 system which did heavy reading from >> an 8.2 server. When I mounted something on the server, the client got a >> "Permission denied" reply. >> >> So, to recap the scenario: >> >> 7.4 NFS client >> 8.2 NFS server >> client mounts a fs from the server (via IPv4, might be interesting to >> look at http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/151681, too, but >> that is unrelated) >> client does heavy i/o on the mounted fs >> server does a mount (on its side, in this case it was from an md device) >> >> --> error: client gets back some NFS error (in this case "permission >> denied") >> > This is a well-known behaviour of NFS server on FreeBSD when some file > system is mounted on a server part. This happens because when mount(8) > mounts something it sends the SIGHUP signal to mountd(8), it then re-reads > exports(5) file and loads new settings into NFS server. Since mountd(8) > flushes current settings, loads new settings in a step-by-step style, all > these changes are happened in nonatomic way. As a result exports settings > in the NFS server are incomplete in any point of time during configuration > loading or reloading. > > This time window allows "denied" clients to access not allowed parts of > exported file systems and "allowed" clients can get access denied errors. > > If you are interested in this topic, you can look on the kern/136865 > and my messages related to this topic (information in [3] is outdated > and in [4] is very outdated): > > 1. NFS exports atomic and on-the-fly atomic updates > http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/136865 > > 2. NFSE: new NFS exports support for FreeBSD > http://nfse.sourceforge.net/ > > 3. NFS exports atomic and on-the-fly atomic updates > http://lists.freebsd.org/pipermail/freebsd-hackers/2009-June/028782.html > > 4. Atomic updates of NFS export lists > http://lists.freebsd.org/pipermail/freebsd-hackers/2006-April/016248.html > > 5. CFT: nfse compatible mode with mountd (NFS exports file) > http://lists.freebsd.org/pipermail/freebsd-fs/2010-May/008421.html > >