Return-Path: Received: from userp1040.oracle.com ([156.151.31.81]:45010 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932296AbbLGRTa convert rfc822-to-8bit (ORCPT ); Mon, 7 Dec 2015 12:19:30 -0500 Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2104\)) Subject: Re: [nfs-utils PATCH] statd: make statd_canonical_name emit a warning if the presentation address maps to an empty hostname From: Chuck Lever In-Reply-To: <20151207170414.GI4405@tonberry.usersys.redhat.com> Date: Mon, 7 Dec 2015 12:19:26 -0500 Cc: Steve Dickson , Linux NFS Mailing List Message-Id: <630B6619-1142-4717-A860-0FC0703FCE0B@oracle.com> References: <1449506523-21897-1-git-send-email-smayhew@redhat.com> <9457C117-431E-40ED-9A3A-5EBE866C7BAF@oracle.com> <20151207170414.GI4405@tonberry.usersys.redhat.com> To: Scott Mayhew Sender: linux-nfs-owner@vger.kernel.org List-ID: > On Dec 7, 2015, at 12:04 PM, Scott Mayhew wrote: > > On Mon, 07 Dec 2015, Chuck Lever wrote: > >> >>> On Dec 7, 2015, at 11:42 AM, Scott Mayhew wrote: >>> >>> Certain name resolution misconfigurations (for example, a hosts file >>> entry with an ip address but no hostnames) can cause get_nameinfo() to >>> return an empty string in buf, which will lead to this cryptic failure: >>> >>> Dec 7 09:37:44 hostname rpc.statd[8024]: Failed to insert: creating >>> /var/lib/nfs/statd/sm/: Is a directory >>> Dec 7 09:37:44 hostname rpc.statd[8024]: STAT_FAIL to >>> hostname.example.com for SM_MON of 192.168.1.2 >>> Dec 7 09:37:44 hostname kernel: lockd: cannot monitor 192.168.1.2 >>> >>> It's better in that case to just go ahead and use the presentation >>> address and log a more helpful warning: >> >> Doesn???t this change wire behavior? Some peers do not appreciate >> receiving a presentation address, which is why statd/sm_notify >> avoid sending them. > > I was just trying to keep it in line with the behavior you had added in > e22f5a9c (statd: statd fails to monitor if no reverse mapping of mon_name > exists). As it stands now, if get_nameinfo() fails outright then the > presentation address is used and we're able to monitor the peer just > fine... but get_nameinfo() succeeds and returns an empty hostname then > we ultimately wind up failing to monitor the peer. OK, I see the “bug-for-bug compatible” red flag in the description of e22f5a9c. I guess this shouldn’t even fire a warning then, it should just return the address. We should correct the documenting comment for statd_canonical_name(). Just delete the sentence that begins “We won’t monitor peers”. Reviewed-by: Chuck Lever >> I think it would be better to _skip_ this address and print the >> warning? IMO. >> > That's actually what I had at first and if you think that's better then > that's fine too. The rest of the errors would still get logged then, > but at least the reason would be a little more apparent. > > -Scott >> >>> Dec 7 10:24:52 hostname rpc.statd[14224]: get_nameinfo returned empty >>> hostname for 10.10.183.219. Fix your name resolution! >>> >>> Signed-off-by: Scott Mayhew >>> --- >>> utils/statd/hostname.c | 6 ++++++ >>> 1 file changed, 6 insertions(+) >>> >>> diff --git a/utils/statd/hostname.c b/utils/statd/hostname.c >>> index c61087c..86d11ca 100644 >>> --- a/utils/statd/hostname.c >>> +++ b/utils/statd/hostname.c >>> @@ -211,6 +211,12 @@ statd_canonical_name(const char *hostname) >>> /* OK to use presentation address, >>> * if no reverse map exists */ >>> return strdup(hostname); >>> + else if (buf[0] == '\0') { >>> + xlog_warn("get_nameinfo returned empty hostname for " >>> + "%s. Fix your name resolution!", >>> + hostname); >>> + return strdup(hostname); >>> + } >>> return strdup(buf); >>> } >>> >>> -- >>> 2.4.3 >>> >>> -- >>> 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 >> >> -- >> Chuck Lever >> >> >> >> > -- > 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 -- Chuck Lever