Return-Path: Received: from verein.lst.de ([213.95.11.211]:42862 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753116AbbLEMCZ (ORCPT ); Sat, 5 Dec 2015 07:02:25 -0500 Date: Sat, 5 Dec 2015 13:02:22 +0100 From: Christoph Hellwig To: Jeff Layton Cc: Christoph Hellwig , "J. Bruce Fields" , Kinglong Mee , linux-nfs@vger.kernel.org Subject: Re: [PATCH RFC] nfsd: serialize layout stateid morphing operations Message-ID: <20151205120222.GA27009@lst.de> References: <20151129084614.42fb1272@tlielax.poochiereds.net> <565BBB03.7020206@gmail.com> <20151130213420.GA31564@fieldses.org> <20151130193313.5bb10791@synchrony.poochiereds.net> <20151201115600.GA1557@lst.de> <20151201174800.407e2c40@synchrony.poochiereds.net> <20151202072504.GA15839@lst.de> <20151203220850.GC19518@fieldses.org> <20151204083803.GA2440@lst.de> <20151204155110.64a352dd@tlielax.poochiereds.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20151204155110.64a352dd@tlielax.poochiereds.net> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Fri, Dec 04, 2015 at 03:51:10PM -0500, Jeff Layton wrote: > > There is no reason not to do it, except for the significant effort > > to implement it a well as a synthetic test case to actually reproduce > > the behavior we want to handle. > > Could you end up livelocking here? Suppose you issue the callback and > the client returns success. He then returns the layout and gets a new > one just before the delay timer pops. We then end up recalling _that_ > layout...rinse, repeat... If we start allowing layoutgets before the whole range has been returned there is a great chance for livelocks, yes. But I don't think we should allow layoutgets to proceed before that.