From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1087BC28CC0 for ; Wed, 29 May 2019 13:24:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E141D2183F for ; Wed, 29 May 2019 13:24:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726702AbfE2NYm (ORCPT ); Wed, 29 May 2019 09:24:42 -0400 Received: from fieldses.org ([173.255.197.46]:39642 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726029AbfE2NYm (ORCPT ); Wed, 29 May 2019 09:24:42 -0400 Received: by fieldses.org (Postfix, from userid 2815) id B0B311E3A; Wed, 29 May 2019 09:24:41 -0400 (EDT) Date: Wed, 29 May 2019 09:24:41 -0400 From: "J. Bruce Fields" To: Steve Dickson Cc: Jeff Layton , linux-nfs@vger.kernel.org, jfajerski@suse.com Subject: Re: [PATCH] manpage: explain why showmount doesn't really work against a v4-only server Message-ID: <20190529132441.GA8235@fieldses.org> References: <20190510215445.1823-1-jlayton@kernel.org> <20190511135442.GA15721@fieldses.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On Wed, May 29, 2019 at 09:15:35AM -0400, Steve Dickson wrote: > Bruce, > > On 5/11/19 9:54 AM, J. Bruce Fields wrote: > > On Fri, May 10, 2019 at 05:54:45PM -0400, Jeff Layton wrote: > >> From: Jeff Layton > >> > >> I occasionally see people that expect valid info when running showmount > >> against a server that may export some or all filesystems via NFSv4. > >> Let's make it clear that it only works by talking to the remote MNT > >> service, and that that may not be available from a v4-only server. > > > > Looks fine. > > > > I wonder if it'd also be helpful for showmount to detect this case and > > say something. E.g. the following (not even compileable, but you get > > the idea). > > > > We've also talked about trying to cobble together an export list by > > scanning the root filesystem over NFSv4, but that's likely to be > > complicated and wouldn't give all the same results without further > > protocol extensions anyway, so I think that idea's dead. > > > > --b. > I'm a bit confused... Does this patch go along with Jeff's manpage change? It's separate. And doesn't even compile. You can ignore it for now. --b. > > steved. > > > > diff --git a/utils/showmount/showmount.c b/utils/showmount/showmount.c > > index 394f5284a219..de9a6d38783a 100644 > > --- a/utils/showmount/showmount.c > > +++ b/utils/showmount/showmount.c > > @@ -115,6 +115,22 @@ static CLIENT *nfs_get_mount_client(const char *hostname, rpcvers_t vers) > > exit(1); > > } > > > > +void warn_if_v4_only(char *hostname) > > +{ > > + struct sockaddr_in server_addr, client_addr; > > + > > + if (fill_ipv4_sockaddr(hostname, &serveraddr)) > > + return; > > + server_addr.sin_port = htnos(NFS_PORT); > > + client_addr.sin_family = 0; > > + client_addr.sin_addr.s_addr = 0; > > + clnt_ping(&server_addr, NFS_PROGRAM, 4, "tcp", &client_addr); > > + > > + if (rpc.createerr == RPC_SUCCESS) > > + printf("Server responding to NFSv4 but not MNT; try mounting " > > + "%s:/ instead of showmount", hostname); > > +} > > + > > int main(int argc, char **argv) > > { > > char hostname_buf[MAXHOSTLEN]; > > @@ -199,6 +215,7 @@ int main(int argc, char **argv) > > fprintf(stderr, "%s: unable to create RPC auth handle.\n", > > program_name); > > clnt_destroy(mclient); > > + warn_if_v4_only(hostname); > > exit(1); > > } > > total_timeout.tv_sec = TOTAL_TIMEOUT; > >