Return-Path: linux-nfs-owner@vger.kernel.org Received: from mail-wi0-f180.google.com ([209.85.212.180]:61426 "EHLO mail-wi0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754062AbaKMT0V (ORCPT ); Thu, 13 Nov 2014 14:26:21 -0500 Received: by mail-wi0-f180.google.com with SMTP id hi2so560093wib.13 for ; Thu, 13 Nov 2014 11:26:20 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20141113190213.GA28516@fieldses.org> References: <5463787A.7080404@RedHat.com> <43A888DD-6114-48FC-AE99-DBE6BBF19A7B@oracle.com> <5463A282.8060803@RedHat.com> <5463C066.8030205@Netapp.com> <5463C3F8.50004@RedHat.com> <5464F10D.3010402@RedHat.com> <20141113190213.GA28516@fieldses.org> Date: Thu, 13 Nov 2014 14:26:20 -0500 Message-ID: Subject: Re: mount default minor version behavior From: Trond Myklebust To: "J. Bruce Fields" Cc: Steve Dickson , Anna Schumaker , Chuck Lever , Benjamin Coddington , Linux NFS Mailing List Content-Type: text/plain; charset=UTF-8 Sender: linux-nfs-owner@vger.kernel.org List-ID: On Thu, Nov 13, 2014 at 2:02 PM, J. Bruce Fields wrote: > On Thu, Nov 13, 2014 at 01:52:09PM -0500, Trond Myklebust wrote: >> On Thu, Nov 13, 2014 at 12:57 PM, Steve Dickson wrote: >> > On 11/12/2014 05:42 PM, Trond Myklebust wrote: >> >>>> NFS v4.0, 4.1, and 4.2 are all part of the same module, though. Is there a way to analyze modules and determine what is compiled in? >> >>> > Maybe come up with some global bit field could be used? >> >>> > Each bit signifies a minor version is enabled... >> >>> > >> >> No. This means that mount.nfs now suddenly needs to know the names of >> >> the NFS modules and how to load them before it calls mount() just so >> >> that it knows which parameters to try. This is a rathole we don't want >> >> to explore... >> > I don't think mount.nfs needs to know any names... Just >> > a file /proc/fs/nfs/mount that tells mount.nfs where >> > to start the negotiation.... >> > >> >> The kernel does not have that information until the NFSv4 module is loaded. > > I still don't get it. All it needs to know is an upper bound--that > could be a single compile-time constant. Is there any reason not to > build that number into the main nfs module? > Firstly, the main nfs module isn't preloaded either. Secondly, that's a layering violation. The main nfs module has no business knowing anything about the sub-modules other than how to load them when needed. If I want to recompile my NFSv4 module to add NFSv4.2 support, then I shouldn't have to recompile the entire contents of my nfs directory. -- Trond Myklebust Linux NFS client maintainer, PrimaryData trond.myklebust@primarydata.com