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=-5.0 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 86C5BC4338F for ; Wed, 18 Aug 2021 15:42:21 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1C7BD60EFF for ; Wed, 18 Aug 2021 15:42:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 1C7BD60EFF Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=fieldses.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 87A888D0001; Wed, 18 Aug 2021 11:42:20 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 82A266B0072; Wed, 18 Aug 2021 11:42:20 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6F18A8D0001; Wed, 18 Aug 2021 11:42:20 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0118.hostedemail.com [216.40.44.118]) by kanga.kvack.org (Postfix) with ESMTP id 51D346B006C for ; Wed, 18 Aug 2021 11:42:20 -0400 (EDT) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id EBBEF267F6 for ; Wed, 18 Aug 2021 15:42:19 +0000 (UTC) X-FDA: 78488617998.05.2CD1CBC Received: from fieldses.org (fieldses.org [173.255.197.46]) by imf26.hostedemail.com (Postfix) with ESMTP id 45037200150B for ; Wed, 18 Aug 2021 15:42:19 +0000 (UTC) Received: by fieldses.org (Postfix, from userid 2815) id 839857C78; Wed, 18 Aug 2021 11:42:17 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.11.0 fieldses.org 839857C78 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fieldses.org; s=default; t=1629301337; bh=FC/u5PHU9ytrdzLe82ecXUKTKca95aRfgvSHOdfIXFI=; h=Date:To:Cc:Subject:References:In-Reply-To:From:From; b=IoOG1oC+EZ/ID0s+DoSOxYoI1E9Tu+nwDKzBTCpDP7QVUB+APnj3BhbpYTcklzF+V cJBa9or753k6Le4EKbbv5VxjwUJjjWE6p3alhBll+UZTrJxa7eUtdrtUsIsXnI25Wg eIt/1B5dUXgfEFVIgoXy37fTL/OHhwDk6bfyZPRg= Date: Wed, 18 Aug 2021 11:42:17 -0400 To: Andy Lutomirski Cc: Linus Torvalds , "Eric W. Biederman" , 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 , "Matthew Wilcox (Oracle)" , 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 =?utf-8?B?S8O2bmln?= , "linux-unionfs@vger.kernel.org" , Linux API , the arch/x86 maintainers , "" , Linux-MM , Florian Weimer , Michael Kerrisk Subject: Re: [PATCH v1 0/7] Remove in-tree usage of MAP_DENYWRITE Message-ID: <20210818154217.GB24115@fieldses.org> References: <20210812084348.6521-1-david@redhat.com> <87o8a2d0wf.fsf@disp2133> <60db2e61-6b00-44fa-b718-e4361fcc238c@www.fastmail.com> <87lf56bllc.fsf@disp2133> <87eeay8pqx.fsf@disp2133> <5b0d7c1e73ca43ef9ce6665fec6c4d7e@AcuMS.aculab.com> <87h7ft2j68.fsf@disp2133> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) From: bfields@fieldses.org (J. Bruce Fields) X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 45037200150B X-Stat-Signature: d7wybppncby9pbm7mfdhtfyiser96uzf Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=fieldses.org header.s=default header.b=IoOG1oC+; dmarc=none; spf=pass (imf26.hostedemail.com: domain of bfields@fieldses.org designates 173.255.197.46 as permitted sender) smtp.mailfrom=bfields@fieldses.org X-HE-Tag: 1629301339-913020 Content-Transfer-Encoding: quoted-printable 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 Fri, Aug 13, 2021 at 05:49:19PM -0700, Andy Lutomirski wrote: > I=E2=80=99ll bite. How about we attack this in the opposite direction:= remove > the deny write mechanism entirely. For what it's worth, Windows has open flags that allow denying read or write opens. They also made their way into the NFSv4 protocol, but knfsd enforces them only against other NFSv4 clients. Last I checked, Samba attempted to emulate them using flock (and there's a comment to that effect on the flock syscall in fs/locks.c). I don't know what Wine does. Pavel Shilovsky posted flags adding O_DENY* flags years ago: https://lwn.net/Articles/581005/ I keep thinking I should look back at those some day but will probably never get to it. I've no idea how Windows applications use them, though I'm told it's common. --b.