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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,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 8837FC43144 for ; Fri, 29 Jun 2018 04:44:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 37BBC249D1 for ; Fri, 29 Jun 2018 04:44:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 37BBC249D1 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=fromorbit.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932516AbeF2Eop (ORCPT ); Fri, 29 Jun 2018 00:44:45 -0400 Received: from ipmail06.adl6.internode.on.net ([150.101.137.145]:2036 "EHLO ipmail06.adl6.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932408AbeF2Eoo (ORCPT ); Fri, 29 Jun 2018 00:44:44 -0400 Received: from ppp59-167-129-252.static.internode.on.net (HELO dastard) ([59.167.129.252]) by ipmail06.adl6.internode.on.net with ESMTP; 29 Jun 2018 14:14:42 +0930 Received: from dave by dastard with local (Exim 4.80) (envelope-from ) id 1fYlGy-0002RK-B4; Fri, 29 Jun 2018 14:44:40 +1000 Date: Fri, 29 Jun 2018 14:44:40 +1000 From: Dave Chinner To: Steve French Cc: ronnie sahlberg , Theodore Tso , linux-fsdevel , LKML , samba-technical , CIFS Subject: Re: config files and how to have persistent Linux kernel Driver/File System configuration info saved Message-ID: <20180629044440.GK19934@dastard> References: <20180628225857.GB1231@thunk.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-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 28, 2018 at 06:24:59PM -0500, Steve French wrote: > On Thu, Jun 28, 2018 at 6:21 PM ronnie sahlberg > wrote: > > > > On Fri, Jun 29, 2018 at 8:58 AM, Theodore Y. Ts'o via samba-technical > > wrote: > > > On Thu, Jun 28, 2018 at 05:37:15PM -0500, Steve French wrote: > > >> Ronnie brought up an interesting point about the problems consistently > > >> configuring file systems (or any Linux module for that matter) so that > > >> reboot doesn't wipe away security or performance tuning changes. > > > > > > In general it's considered best practice to make the file system > > > auto-tune itself as much as possible, because the sad fact is that > > > 99.9999% of the customers aren't going to bother to add any tuning > > > parameters. So there hasn't been a push to try to create something > > > more complex, because it's generally not needed. > > > > True, but in these cases I think we are more looking at server or > > mountpoint specific options than > > actual fs tuning. > > > > For example nfsmount.conf can be used to say "only use NFSv4 when > > accessing server abc" etc. > > For the case of CIFS I could imagine that an administrator might want > > to set "disable smb1 protocol globally" > > Or perhaps > "disable smb1 on " ... various public networks but allow it on > private networks The way the policy is configured depends on the mechanism used to configure the policy. If it's a sysctl or a mount option, then we've already got everything we need. If it's something dynamic in sysfs, then I think you're on your own. FYI, I have been looking at making sysctl be able to work on /sys rather than just /proc/sys (I have a 10 line hack to enable it) so we could re-use it with custom per-mount error config files in /etc/xfs/ for XFS that we inject based on a uevent delivered to udev. It works, but the fact is modifying sysctl in this way exposes it to a whole bunch of stuff sysctl doesn't understand, shouldn't be accessing and/or trying modify. i.e. sysctl is disturbingly dumb, and it gets away with it because of it's restricted scope and API presented by /proc/sys. So, really, I'm probably just going roll our own sysfs config file mechanism into xfs_spaceman (probably based on the new config file parser we have for mkfs.xfs) and hide the mess with a nice, simple xfs_admin interface for udev to call. i.e. roll our own :) Cheers, Dave. -- Dave Chinner david@fromorbit.com