Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:63521 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756294Ab0A0Wa5 (ORCPT ); Wed, 27 Jan 2010 17:30:57 -0500 Message-ID: <4B60BE9E.6020702@redhat.com> Date: Wed, 27 Jan 2010 17:30:54 -0500 From: Peter Staubach To: Chuck Lever CC: Steve Dickson , Linux NFS Mailing list Subject: Re: [PATCH] mount.nfs: Don't fail mounts when /etc/netconfig is nonexistent References: <4B606CA5.2090607@RedHat.com> <4B60816E.5070108@oracle.com> <4B608905.90708@RedHat.com> <25FE1491-19BF-47AC-8AF2-50D474E67B7D@oracle.com> In-Reply-To: <25FE1491-19BF-47AC-8AF2-50D474E67B7D@oracle.com> Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 Chuck Lever wrote: > On Jan 27, 2010, at 1:42 PM, Steve Dickson wrote: >> On 01/27/2010 01:09 PM, Chuck Lever wrote: >>>> Author: Steve Dickson >>>> Date: Wed Jan 27 11:19:00 2010 -0500 >>>> >>>> In a very sparse environments certain system files (like >>>> /etc/netconfig) may not exist. In these environments don't >>>> fail mount if all the need information (like network protocols) >>>> exist and are well known. >>>> >>>> Signed-off-by: Steve Dickson >>> >>> I totally disagree with this. If HAVE_LIBTIRPC is set, then the runtime >>> TI-RPC package should be installed, in its entirety, on the run-time >>> systems. If autoconf and RPM can't trust the given dependency >>> information, then all bets are off. >> Well in some environments "all bets are off" is just not good enough... > > Limited disk space does not mean that RPM is suddenly allowed to ignore > dependencies. Clearly someone decided that it was OK to install only > part of the TI-RPC run-time on this system, despite the dependency > nfs-utils has on libtirpc. > >> Mount has always worked in these type of environments before and >> I think we should continue to... > > No one is arguing that point. > >>> The right fix is to either: >>> >>> a) install a non-TI-RPC version of mount.nfs, or >>> >>> b) make sure /etc/netconfig is available when RPM, pkgconfig, and >>> autoconf say it should be. >>> >> Sparse environments generally have a finite amount of space, that >> is simple unchangeable... so the above "luxuries" are simply not >> available... > > I'm sorry you feel that /etc/netconfig is a luxury, but the fact is it's > currently a mandatory part of the TI-RPC run-time. Why be surprised if > TI-RPC based applications stop working when the run-time they depend on > is incorrectly installed? > > If /etc/rpc and /etc/protocols are installed on this system, then > there's no reason to exclude /etc/netconfig. The file is all of 768 > bytes (and can be made smaller immediately by leaving out the block > comment at the top). If there really is no room for an additional file, > then you need a different solution (see below). > > Frankly, if disk space is so tight on this system, you should embrace > using the non-TI-RPC mount.nfs, because it's disk footprint is > significantly smaller than the current TI-RPC based mount.nfs, and you > get exactly the functionality that you get with your patch applied. > >>> I assume since you are not patching other parts of mount.nfs that look >>> for /etc/rpc and /etc/protocols that these files _do_ exist? Or does >>> glibc also do this hack of filling in well-known values? >>> >> Lets keep this in perspective... the "well-known" values in this patch >> things like TCP and UDP... when protocol == IPPROTO_TCP the well known >> value >> is "tcp" (or "tcp6" depending on the family)... Values that have not >> changed for years and will not change for years... >> >> On the umount side, the file should not be consulted in the first place >> since all the information needed in /etc/mtab... Of course things >> can change between mount and umounts but I truly do no think the >> meaning of "udp" will change from being IPPROTO_UDP.... >> >> Making mount more bullet proof and allowing it (continue to) work in all >> different types of environments is a good thing... imho... > > You've fundamentally misunderstood my objection to your patch. > > In nfs-utils, we've replaced the glibc RPC implementation with TI-RPC. > Today, if you want the TI-RPC versions of these utilities to "just work" > then the whole TI-RPC run-time must be installed on the target systems. > Note well that the TI-RPC enabled statd will also fail to start if > /etc/netconfig does not exist, and this will cause NFS mounts to fail as > well. Likewise, a TI-RPC enabled mountd will fail to start in this > situation. > > Now, if you want to ensure that TI-RPC applications will continue to > work in the absence of parts of the TI-RPC run-time, then you should > address that in libtirpc, not in every application that uses it. > /etc/netconfig is not a part of mount.nfs, it's a part of TI-RPC. > > It also appears that your new logic might assume the values of "tcp" and > "udp" when an admin purposely excludes them from /etc/netconfig. What > if an admin wants to start only IPv6 listeners for statd, nfsd, and > mountd? Somehow, mounting "tcp" and "udp" still work, even though we > claim in the man page that these are netids, not protocol names. That > would be a bug. > Chuck, it feels as if you are under the impression that this is a general purpose deployment that Steve is attempting to make to work. It is not. It is a very restricted use, ie. to install a system. Thus, the resources available are very restricted. The restriction is not diskspace, per se, but the memory footprint which would be required to hold it. The suggestion to use the non-TI-RPC version is interesting, but has some very negative ramifications. It would mean that we would have to test the TI-RPC flavor and the non-TI-RPC flavor. It would also limit future development to that which could be supported via the non-TI-RPC version. This seems unnecessarily limiting. While I don't agree with what the anaconda folks have done, picking and choosing as they have, they have done so. I think that we should work with them to figure out why they have chosen to do so and whether it is valid or not. All that said, what is the technical problem with including this support? There is no possibility that "tcp" or "udp" will ever change meaning, at least not in our lifetimes. The bottom line is that I could agree, that this isn't the most aesthetically pleasing architecture and implementation. However, sometimes, the code must run in a non-perfect world and hence, compromises must be made. Thanx... ps