Return-Path: Received: from fieldses.org ([173.255.197.46]:55886 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932709AbdC2BW6 (ORCPT ); Tue, 28 Mar 2017 21:22:58 -0400 Date: Tue, 28 Mar 2017 21:22:52 -0400 From: "J. Bruce Fields" To: Jeff Layton Cc: Chuck Lever , linux-nfs@vger.kernel.org Subject: Re: [PATCH] svcrdma: set XPT_CONG_CTRL flag for bc xprt Message-ID: <20170329012252.GB20963@fieldses.org> References: <20170326231254.1319.26075.stgit@manet.1015granger.net> <1490577699.6879.1.camel@poochiereds.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1490577699.6879.1.camel@poochiereds.net> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Sun, Mar 26, 2017 at 09:21:39PM -0400, Jeff Layton wrote: > On Sun, 2017-03-26 at 19:27 -0400, Chuck Lever wrote: > > Are we certain that all client implementations (including > > backchannel clients) will do something useful when presented with > > such a rejection? At least in the backchannel case, the Linux server > > had no idea what to do with RPC_PROG_MISMATCH on the backchannel. > > The workload stopped dead, no error report anywhere. > > > > Ouch. I think this would get translated into EPROTONOSUPPORT in the > client code. That should have ended up with nfsd4_mark_cb_down being > called with that error?...but I think that function may be effectively > neutered: Are we worrying now about a server that tries to open an NFSv4.0 callback connection using UDP? That would be a very broken server. And broken in a way that I think is pretty unlikely to actually happen in practice. Maybe I'm missing something. > static void warn_no_callback_path(struct nfs4_client *clp, int reason) > { > dprintk("NFSD: warning: no callback path to client %.*s: error %d\n", > (int)clp->cl_name.len, clp->cl_name.data, reason); > } In NFSv4.0 a failing callback connection is absolutely normal (e.g. if the client is behind a firewall). We might want to provide some better diagnostics to help people figure out why a given client isn't getting delegations, but we don't want to log this by default. Even in the 4.1 case I wonder if some pretty common failures (e.g. losing contact with the client) might get noticed by the callback code first. So, dprintk is right here. --b. > > Note that it emits a dprintk instead of a printk. Should we promote > that to something more visible? > > > net/sunrpc/xprtrdma/svc_rdma_transport.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c > > index c13a5c3..fc8f14c 100644 > > --- a/net/sunrpc/xprtrdma/svc_rdma_transport.c > > +++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c > > @@ -127,6 +127,7 @@ static struct svc_xprt *svc_rdma_bc_create(struct svc_serv *serv, > > xprt = &cma_xprt->sc_xprt; > > > > svc_xprt_init(net, &svc_rdma_bc_class, xprt, serv); > > + set_bit(XPT_CONG_CTRL, &xprt->xpt_flags); > > serv->sv_bc_xprt = xprt; > > > > dprintk("svcrdma: %s(%p)\n", __func__, xprt); > > > > -- > > 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