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=-3.8 required=3.0 tests=BAYES_00, 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 AD4ADC433E1 for ; Thu, 27 Aug 2020 15:58:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 97AEB22CAF for ; Thu, 27 Aug 2020 15:58:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728063AbgH0P6H convert rfc822-to-8bit (ORCPT ); Thu, 27 Aug 2020 11:58:07 -0400 Received: from eu-smtp-delivery-151.mimecast.com ([185.58.86.151]:35092 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727894AbgH0P6G (ORCPT ); Thu, 27 Aug 2020 11:58:06 -0400 Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-127-1uCyu8HkODWHTq8BSgI4eA-1; Thu, 27 Aug 2020 16:58:02 +0100 X-MC-Unique: 1uCyu8HkODWHTq8BSgI4eA-1 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; Thu, 27 Aug 2020 16:58:02 +0100 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; Thu, 27 Aug 2020 16:58:02 +0100 From: David Laight To: 'Christoph Hellwig' , Linus Torvalds , Al Viro , "Michael Ellerman" , "x86@kernel.org" CC: "linux-fsdevel@vger.kernel.org" , "linux-arch@vger.kernel.org" , "linuxppc-dev@lists.ozlabs.org" , Kees Cook , "linux-kernel@vger.kernel.org" Subject: RE: [PATCH 01/10] fs: don't allow kernel reads and writes without iter ops Thread-Topic: [PATCH 01/10] fs: don't allow kernel reads and writes without iter ops Thread-Index: AQHWfINAnoKBzQpz30W83mcBiLuV+KlMG9NA Date: Thu, 27 Aug 2020 15:58:02 +0000 Message-ID: References: <20200827150030.282762-1-hch@lst.de> <20200827150030.282762-2-hch@lst.de> In-Reply-To: <20200827150030.282762-2-hch@lst.de> 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 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=C51A453 smtp.mailfrom=david.laight@aculab.com X-Mimecast-Spam-Score: 0.001 X-Mimecast-Originator: aculab.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: Christoph Hellwig > Sent: 27 August 2020 16:00 > > Don't allow calling ->read or ->write with set_fs as a preparation for > killing off set_fs. All the instances that we use kernel_read/write on > are using the iter ops already. > > If a file has both the regular ->read/->write methods and the iter > variants those could have different semantics for messed up enough > drivers. Also fails the kernel access to them in that case. Is there a real justification for that? For system calls supplying both methods makes sense to avoid the extra code paths for a simple read/write. Any one stupid enough to make them behave differently gets what they deserve. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)