Return-Path: Received: from fieldses.org ([173.255.197.46]:55574 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1422719AbcFMUyl (ORCPT ); Mon, 13 Jun 2016 16:54:41 -0400 Date: Mon, 13 Jun 2016 16:54:40 -0400 From: "J. Bruce Fields" To: Trond Myklebust Cc: Anna Schumaker , "linux-nfs@vger.kernel.org" Subject: Re: [PATCH 0/3] fix backchannel crash due to multipath Message-ID: <20160613205440.GA20974@fieldses.org> References: <20160613182104.GA19825@fieldses.org> <285640B8-5ACD-4108-BFF6-F9342E857102@primarydata.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <285640B8-5ACD-4108-BFF6-F9342E857102@primarydata.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Mon, Jun 13, 2016 at 07:24:06PM +0000, Trond Myklebust wrote: > > > On 6/13/16, 14:21, "J. Bruce Fields" wrote: > > >On March 24 J. Bruce Fields said: > >> pynfs can crash the nfs server since the new multipath code. The > >> problem is that pynfs uses the same tcp connection for multiple v4 > >> clients (something the spec explicitly allows). The callback client in > >> such cases has to share the same rpc_xprt. The new rpc code, when it > >> creates two callback clients sharing the same rpc_xprt, ends up trying > >> to keep that rpc_xprt on the lists of two different rpc_xprt_switch's. > >> The first symptom I see is a list corruption warning. > >> > >> So, I'm enforcing the requirement that there be only one backchannel > >> rpc_xprt_switch per tcp connection by doing as we do in the rpc_xprt > >> case: keeping a pointer to it in the svc_xprt, and using that when it's > >> available instead of allocating a new one. > > > >> That's a pretty straightforward fix (and I've verified it works), but > >> doesn't look very elegant. If there's a better solution, I'm all ears. > > > >I haven't come up with anything neater, and kind of need the crash > >fixed. ACK or NACK? I can take it through my tree if it's an ACK. > > > >--b. > > > > Ack Thanks!--b.