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=-0.8 required=3.0 tests=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 70040C33CB1 for ; Wed, 15 Jan 2020 10:21:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3CDF12075B for ; Wed, 15 Jan 2020 10:21:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729715AbgAOKVt convert rfc822-to-8bit (ORCPT ); Wed, 15 Jan 2020 05:21:49 -0500 Received: from eu-smtp-delivery-151.mimecast.com ([207.82.80.151]:26496 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729631AbgAOKVt (ORCPT ); Wed, 15 Jan 2020 05:21:49 -0500 Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-224-1qiFO4UbN9aTPeO6iSwoTA-1; Wed, 15 Jan 2020 10:21:46 +0000 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) by AcuMS.aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Wed, 15 Jan 2020 10:21:45 +0000 Received: from AcuMS.Aculab.com ([fe80::43c:695e:880f:8750]) by AcuMS.aculab.com ([fe80::43c:695e:880f:8750%12]) with mapi id 15.00.1347.000; Wed, 15 Jan 2020 10:21:45 +0000 From: David Laight To: "'ira.weiny@intel.com'" , "linux-kernel@vger.kernel.org" CC: Alexander Viro , "Darrick J. Wong" , Dan Williams , "Dave Chinner" , Christoph Hellwig , "Theodore Y. Ts'o" , Jan Kara , "linux-ext4@vger.kernel.org" , "linux-xfs@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" Subject: RE: [RFC PATCH V2 09/12] fs: Prevent mode change if file is mmap'ed Thread-Topic: [RFC PATCH V2 09/12] fs: Prevent mode change if file is mmap'ed Thread-Index: AQHVx+xw3fI16+EnrkucPW5Ge+vrG6frihyw Date: Wed, 15 Jan 2020 10:21:45 +0000 Message-ID: <06258747f6824a35adfaa999ab4c2261@AcuMS.aculab.com> References: <20200110192942.25021-1-ira.weiny@intel.com> <20200110192942.25021-10-ira.weiny@intel.com> In-Reply-To: <20200110192942.25021-10-ira.weiny@intel.com> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-MC-Unique: 1qiFO4UbN9aTPeO6iSwoTA-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >From ira.weiny@intel.com > Sent: 10 January 2020 19:30 > > Page faults need to ensure the inode mode is correct and consistent with > the vmf information at the time of the fault. There is no easy way to > ensure the vmf information is correct if a mode change is in progress. > Furthermore, there is no good use case to require a mode change while > the file is mmap'ed. > > Track mmap's of the file and fail the mode change if the file is > mmap'ed. This seems wrong to me. I presume the 'mode changes' are from things like 'chmod -w ...'. mmap() should be no different to open(). Only the permissions set when the file is opened count. Next you'll be stopping unlink() when a file is open :-) David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)