Return-Path: Received: from fieldses.org ([173.255.197.46]:51940 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932167AbcGAUHo (ORCPT ); Fri, 1 Jul 2016 16:07:44 -0400 Date: Fri, 1 Jul 2016 16:07:42 -0400 From: Bruce Fields To: Marc Eshel Cc: linux-nfs@vger.kernel.org Subject: Re: grace period Message-ID: <20160701200742.GA24269@fieldses.org> References: <1465939516-44769-1-git-send-email-trond.myklebust@primarydata.com> <20160701160857.GB20327@fieldses.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Sender: linux-nfs-owner@vger.kernel.org List-ID: On Fri, Jul 01, 2016 at 10:31:55AM -0700, Marc Eshel wrote: > It used to be that sending KILL signal to lockd would free locks and start > Grace period, and when setting nfsd threads to zero, nfsd_last_thread() > calls nfsd_shutdown that called lockd_down that I believe was causing both > freeing of locks and starting grace period or maybe it was setting it back > to a value > 0 that started the grace period. OK, apologies, I didn't know (or forgot) that. > Any way starting with the kernels that are in RHEL7.1 and up echo 0 > > /proc/fs/nfsd/threads doesn't do it anymore, I assume going to common > grace period for NLM and NFSv4 changed things. > The question is how to do IP fail-over, so when a node fails and the IP is > moving to another node, we need to go into grace period on all the nodes > in the cluster so the locks of the failed node are not given to anyone > other than the client that is reclaiming his locks. Restarting NFS server > is to distractive. What's the difference? Just that clients don't have to reestablish tcp connections? --b. > For NFSv3 KILL signal to lockd still works but for > NFSv4 have no way to do it for v4. > Marc. > > > > From: Bruce Fields > To: Marc Eshel/Almaden/IBM@IBMUS > Cc: linux-nfs@vger.kernel.org > Date: 07/01/2016 09:09 AM > Subject: Re: grace period > > > > On Thu, Jun 30, 2016 at 02:46:19PM -0700, Marc Eshel wrote: > > I see that setting the number of nfsd threads to 0 (echo 0 > > > /proc/fs/nfsd/threads) is not releasing the locks and putting the server > > > in grace mode. > > Writing 0 to /proc/fs/nfsd/threads shuts down knfsd. So it should > certainly drop locks. If that's not happening, there's a bug, but we'd > need to know more details (version numbers, etc.) to help. > > That alone has never been enough to start a grace period--you'd have to > start knfsd again to do that. > > > What is the best way to go into grace period, in new version of the > > kernel, without restarting the nfs server? > > Restarting the nfs server is the only way. That's true on older kernels > true, as far as I know. (OK, you can apparently make lockd do something > like this with a signal, I don't know if that's used much, and I doubt > it works outside an NFSv3-only environment.) > > So if you want locks dropped and a new grace period, then you should run > "systemctl restart nfs-server", or your distro's equivalent. > > But you're probably doing something more complicated than that. I'm not > sure I understand the question.... > > --b. > > > >