Return-Path: linux-nfs-owner@vger.kernel.org Received: from mx12.netapp.com ([216.240.18.77]:20951 "EHLO mx12.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753906Ab3AWSNg convert rfc822-to-8bit (ORCPT ); Wed, 23 Jan 2013 13:13:36 -0500 From: "Myklebust, Trond" To: Peter Staubach CC: Alex Bligh , "linux-nfs@vger.kernel.org" , "ian.campbell@citrix.com" Subject: Re: Fatal crash with NFS, AIO & tcp retransmit Date: Wed, 23 Jan 2013 18:13:34 +0000 Message-ID: <4FA345DA4F4AE44899BD2B03EEEC2FA918332049@sacexcmbx05-prd.hq.netapp.com> References: <93D3AE9B4990994B2BCA75A9@Ximines.local> <4FA345DA4F4AE44899BD2B03EEEC2FA915C163B9@SACEXCMBX04-PRD.hq.netapp.com> <4FA345DA4F4AE44899BD2B03EEEC2FA915C17543@SACEXCMBX04-PRD.hq.netapp.com> <734E2E0455BD4515C657BA69@Ximines.local> <4FA345DA4F4AE44899BD2B03EEEC2FA915C1781E@SACEXCMBX04-PRD.hq.netapp.com> <4FA345DA4F4AE44899BD2B03EEEC2FA91832D572@sacexcmbx05-prd.hq.netapp.com> <5B18F9B0446E7F3CAA3BD81D@nimrod.local> <4FA345DA4F4AE44899BD2B03EEEC2FA918331EF5@sacexcmbx05-prd.hq.netapp.com> In-Reply-To: Content-Type: text/plain; charset=US-ASCII MIME-Version: 1.0 Sender: linux-nfs-owner@vger.kernel.org List-ID: On Wed, 2013-01-23 at 12:48 -0500, Peter Staubach wrote: > Hi. > > The theory is that the modified pages which need to get written to the server can't be released until they have been successfully written and committed to stable storage on the server. > > They can't disappear until they have been successfully transmitted and a response received. The problem here is that there were two requests sent or being sent and the page(s) can't be released until everyone, including TCP and such, are done with them. > > ps Right. The O_DIRECT write() system call will not return until it gets a reply. Similarly, we don't mark an aio/dio request as complete until it too gets a reply. So the data for those requests that need retransmission is still available to be resent through the socket. Cheers Trond > -----Original Message----- > From: linux-nfs-owner@vger.kernel.org [mailto:linux-nfs-owner@vger.kernel.org] On Behalf Of Alex Bligh > Sent: Wednesday, January 23, 2013 12:42 PM > To: Myklebust, Trond > Cc: linux-nfs@vger.kernel.org; ian.campbell@citrix.com; Alex Bligh > Subject: Re: Fatal crash with NFS, AIO & tcp retransmit > > Trond, > > --On 23 January 2013 17:37:08 +0000 "Myklebust, Trond" > wrote: > > >> If you break the connection, and the written data is now not > >> available to dom0 (as it's been mapped out), how would it ever get > >> resent? IE it's not going to be available to the RPC layer either. > > > > There are typically more than 1 outstanding RPC call at any one time. > > Breaking the connection would affect those other RPC calls. > > I understand that. I meant 'how does the write which failed ever get retransmitted now the data to be written has been lost?' > > -- > Alex Bligh > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html -- Trond Myklebust Linux NFS client maintainer NetApp Trond.Myklebust@netapp.com www.netapp.com