From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755791Ab2FZLKe (ORCPT ); Tue, 26 Jun 2012 07:10:34 -0400 Received: from fieldses.org ([174.143.236.118]:55621 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754103Ab2FZLKb (ORCPT ); Tue, 26 Jun 2012 07:10:31 -0400 Date: Tue, 26 Jun 2012 07:10:24 -0400 From: Fields James To: Namjae Jeon Cc: "Myklebust, Trond" , Morton Andrew , Harrosh Boaz , "" , linux-kernel , Namjae Jeon , Vivek Trivedi , Amit Sahrawat Subject: Re: [RFC PATCH] nfs: Add NFS3PROC_UMOUNT procedure. Message-ID: <20120626111024.GB14279@fieldses.org> References: <1340448406-10161-1-git-send-email-linkinjeon@gmail.com> <02B16139-AFD6-4F06-99C0-C406B1A7E1DC@netapp.com> <20120623155710.GA10787@fieldses.org> <20120623160923.GB10787@fieldses.org> <20120625113025.GB16920@fieldses.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 26, 2012 at 02:51:52PM +0900, Namjae Jeon wrote: > 2012/6/25, Fields James : > > On Sun, Jun 24, 2012 at 02:12:49PM +0900, Namjae Jeon wrote: > >> 2012/6/24, Fields James : > >> > On Sat, Jun 23, 2012 at 11:57:10AM -0400, Fields James wrote: > >> >> On Sat, Jun 23, 2012 at 03:52:20PM +0000, Myklebust, Trond wrote: > >> >> > The other objection is that NFSv3 already has a way to do this via > >> >> > the > >> >> > MOUNT protocol. We already call MOUNTPROC3_UMNT/MOUNTPROC_UMNT on > >> >> > unmount of a filesystem. > >> >> > > >> >> > The problem with this approach is that if the NFS client crashes > >> >> > before > >> >> > it can call this function, then the server never gets notified. That > >> >> > is > >> >> > a problem that your patch has too... > >> >> > >> >> Yes. Could you instead work on describing *exactly* what the original > >> >> problem was that prompted this? > >> > > >> > ("You" here meaning Namjae Jeon, of course). > >> > > >> > And note here we've all read the changelog, that's not what I'm asking > >> > for. > >> > > >> > I want to know the details of *your* specific case. "I have X clients > >> > that I use for Y, periodically I want to unmount the exported > >> > filesystem > >> > to do Z, I tried doing W but it didn't work...". > >> As you remember, We discussed this > >> issue(http://www.spinics.net/lists/linux-nfs/msg29997.html) with you > >> before. you guided me to use exportfs -f call on nfs server. > >> It is hard to use this method on our system > > > > Why is it hard? > Two target are connected by only nfs.. we can't manually hand exportfs -f.. So how can you call umount? --b. > And I should make each new App on client / server to call exportfs -f. > > > > Could you hack umount to do the equivalent of "exportfs -f" before > > calling the umount? > Good Idea! I will check your suggestion. > > > > >> and nomally the user is > >> thinking it is problem device busy happen after umounting. > >> > >> The details of specific case. > >> 1. There are two target or two PC. and Client want to access files of > >> usb device on server. > >> 2. the client try to mount usb mount point using nfs on sever after > >> plugging usb device. > >> 3. we try to umount mount point directory on client. > >> 4. and when we try to umount usb device mount directory server, device > >> busy message occured like this (umount: can't umount /mnt: Device or > >> resource busy) > > > > Right, so I don't think you want protocol modifications. They take a > > few years to get hammered out and then make it into implementations, and > > they won't help a great deal with your problem anyway. (Because of > > problems like the possibility of lost "unmount" calls that Trond > > mentions.) > > > > Either modify umount itself to flush the export cache before attempting > > the unmount, or if that doesn't work perhaps you could patch the kernel > > to notify nfsd on unmount and let it attemt to clear its caches before > > deciding whether the filesystem is busy. > After checking your suggestion I will share with you. > Thanks a lot. James. > > > > --b. > >