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=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 9C6D3C4338F for ; Fri, 20 Aug 2021 02:18:39 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 486C460FF2 for ; Fri, 20 Aug 2021 02:18:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 486C460FF2 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id D8AC76B0071; Thu, 19 Aug 2021 22:18:38 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D3B8A6B0072; Thu, 19 Aug 2021 22:18:38 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C02638D0001; Thu, 19 Aug 2021 22:18:38 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0143.hostedemail.com [216.40.44.143]) by kanga.kvack.org (Postfix) with ESMTP id A39366B0071 for ; Thu, 19 Aug 2021 22:18:38 -0400 (EDT) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 4F856180269F7 for ; Fri, 20 Aug 2021 02:18:38 +0000 (UTC) X-FDA: 78493850316.20.5E411C2 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf04.hostedemail.com (Postfix) with ESMTP id B4DC650000A1 for ; Fri, 20 Aug 2021 02:18:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=XSjREASVEvDR589eO6Ijn0bZU+wzCen1b/RgVCWKb2s=; b=H4jwt/iwZH+J07Ms0xFu4grwYh 6omomnqIBNoFTTCWp0YdBtyQp6jA2olzsf31U0XPG+HjMeaBZRs6AKaozY0P7j9wsPCCKMHV+vcER 8z9egjZURpkPkQH/OQxf1R97pwRN+turgoLRoTu0EcSh+eFkmshp0nG2kC+CinoDpwFLYTez5MVIE dnAwHIZ49meqESwtfsgqjqkWTTWhSQ0k+MoZ9+W5hfZduTGkhy+4t9GN3vIkMiqrAqjoUGsRUvudq AKOjDs5LHGbOnIPKy8zq1pyp9gmQPn4If4jfhDdgb3xEpRCGi3fZQsC8utNkSpZz5H8cEI5OeYP4Z pYYnbQdQ==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mGtys-005stK-2d; Fri, 20 Aug 2021 02:10:21 +0000 Date: Fri, 20 Aug 2021 03:10:02 +0100 From: Matthew Wilcox To: Linus Torvalds Cc: Jeff Layton , "Eric W. Biederman" , Andy Lutomirski , David Laight , David Hildenbrand , Linux Kernel Mailing List , Andrew Morton , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Al Viro , Alexey Dobriyan , Steven Rostedt , "Peter Zijlstra (Intel)" , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Petr Mladek , Sergey Senozhatsky , Andy Shevchenko , Rasmus Villemoes , Kees Cook , Greg Ungerer , Geert Uytterhoeven , Mike Rapoport , Vlastimil Babka , Vincenzo Frascino , Chinwen Chang , Michel Lespinasse , Catalin Marinas , Huang Ying , Jann Horn , Feng Tang , Kevin Brodsky , Michael Ellerman , Shawn Anastasio , Steven Price , Nicholas Piggin , Christian Brauner , Jens Axboe , Gabriel Krisman Bertazi , Peter Xu , Suren Baghdasaryan , Shakeel Butt , Marco Elver , Daniel Jordan , Nicolas Viennot , Thomas Cedeno , Collin Fijalkovich , Michal Hocko , Miklos Szeredi , Chengguang Xu , Christian =?iso-8859-1?Q?K=F6nig?= , "linux-unionfs@vger.kernel.org" , Linux API , the arch/x86 maintainers , "" , Linux-MM , Florian Weimer , Michael Kerrisk Subject: Re: Removing Mandatory Locks Message-ID: References: <5b0d7c1e73ca43ef9ce6665fec6c4d7e@AcuMS.aculab.com> <87h7ft2j68.fsf@disp2133> <87k0kkxbjn.fsf_-_@disp2133> <0c2af732e4e9f74c9d20b09fc4b6cbae40351085.camel@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: B4DC650000A1 Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b="H4jwt/iw"; dmarc=none; spf=none (imf04.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org X-Rspamd-Server: rspam04 X-Stat-Signature: ugmpy54o9ixnkn7nun5ik4i597ci7ksr X-HE-Tag: 1629425917-682541 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Aug 19, 2021 at 01:31:35PM -0700, Linus Torvalds wrote: > Yes, yes, currently if you turn off CONFIG_MANDATORY_FILE_LOCKING, we > already do that > > VFS: "mand" mount option not supported > > warning print, but then we fail the mount. > > If CONFIG_MANDATORY_FILE_LOCKING goes away entirely, it might make > sense to turn that warning into something bigger, but then let the > mount continue - since now that "mand" flag would be purely a legacy > thing. > > And yes, if we do that, we'd want the warning to be a big ugly thing, > just to make people very aware of it happening. Right now it's a > one-liner that is easy to miss, and the "oh, the mount failed" is the > thing that hopefully informs people about the fact that they need to > enable CONFIG_MANDATORY_FILE_LOCKING. When I ripped out the NFS "intr" mount option fourteen years ago, I just turned it into a noop (commit 150030b78a45). It has greatly amused me every article I've read that's been written since then that recommends using it. Just shows how much tribal knowledge we have. I think this is a little different, though; I was essetially making the *wanted* behaviour of 'intr' the default (and disabling the unwanted behaviour). With 'mand', we're losing the behaviour entirely, and it's plausible that someone might care. Maybe something more like the old sys_bdflush implementation? if (msg_count < 5) { msg_count++; printk(KERN_INFO "warning: process `%s' used the obsolete bdflush" " system call\n", current->comm); printk(KERN_INFO "Fix your initscripts?\n"); }