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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 DA3B0C433E2 for ; Sat, 29 Aug 2020 09:26:02 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 587AE20936 for ; Sat, 29 Aug 2020 09:26:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 587AE20936 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4BdrgC5qwQzDqgN for ; Sat, 29 Aug 2020 19:25:59 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=lst.de (client-ip=213.95.11.211; helo=verein.lst.de; envelope-from=hch@lst.de; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=lst.de Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4Bdrcr1GF7zDqfX for ; Sat, 29 Aug 2020 19:23:54 +1000 (AEST) Received: by verein.lst.de (Postfix, from userid 2407) id 2BE3968C4E; Sat, 29 Aug 2020 11:23:48 +0200 (CEST) Date: Sat, 29 Aug 2020 11:23:47 +0200 From: 'Christoph Hellwig' To: David Laight Subject: Re: [PATCH 01/10] fs: don't allow kernel reads and writes without iter ops Message-ID: <20200829092347.GA8833@lst.de> References: <20200827150030.282762-1-hch@lst.de> <20200827150030.282762-2-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "linux-arch@vger.kernel.org" , Kees Cook , "x86@kernel.org" , "linuxppc-dev@lists.ozlabs.org" , "linux-kernel@vger.kernel.org" , Al Viro , "linux-fsdevel@vger.kernel.org" , Linus Torvalds , 'Christoph Hellwig' Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu, Aug 27, 2020 at 03:58:02PM +0000, David Laight wrote: > 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. Al asked for it as two of our four in-tree instances do have weird semantics, and we can't change that any more. And the other two don't make sense to be used with kernel_read and kernel_write ( (/dev/null and /dev/zero).