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=-2.5 required=3.0 tests=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 8D2F8C433DF for ; Wed, 24 Jun 2020 18:24:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 712DD20767 for ; Wed, 24 Jun 2020 18:24:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2406082AbgFXSYl (ORCPT ); Wed, 24 Jun 2020 14:24:41 -0400 Received: from verein.lst.de ([213.95.11.211]:45536 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405892AbgFXSYl (ORCPT ); Wed, 24 Jun 2020 14:24:41 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id E110B68B02; Wed, 24 Jun 2020 20:24:37 +0200 (CEST) Date: Wed, 24 Jun 2020 20:24:37 +0200 From: Christoph Hellwig To: Linus Torvalds Cc: Christoph Hellwig , Al Viro , Luis Chamberlain , Kees Cook , Iurii Zaikin , Linux Kernel Mailing List , linux-fsdevel Subject: Re: [PATCH 03/11] fs: add new read_uptr and write_uptr file operations Message-ID: <20200624182437.GB26405@lst.de> References: <20200624162901.1814136-1-hch@lst.de> <20200624162901.1814136-4-hch@lst.de> <20200624175548.GA25939@lst.de> <20200624181437.GA26277@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) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, Jun 24, 2020 at 11:20:26AM -0700, Linus Torvalds wrote: > On Wed, Jun 24, 2020 at 11:14 AM Christoph Hellwig wrote: > > > > So we'd need new user copy functions for just those cases > > No. We'd open-code them. They'd look at "oh, I'm supposed to use a > kernel pointer" and just use those. > > IOW, basically IN THE CODE that cares (and the whole argument is that > this code is one or two special cases) you do > > /* This has not been converted to the new world order */ > if (get_fs() == KERNEL_DS) memcpy(..) else copy_from_user(); > > You're overdesigning things. You're making them more complex than they > need to be. I wish it was so simple. I really don't like overdesigns, trust me. But please take a look at setsockopt and all the different instances (count 90 .setsockopt wireups, and they then branch out into various subroutines as well). I really don't want to open code that there, but we could do helper specific to setsockopt. Honestly my preference would be to say that no eBPF isn't actually a user API and just rip out the crap added to it, but I fear that is not an option. Because in that case we'd basically be done. > Basically, I do *NOT* want to pollute the VFS layer with new > interfaces that shouldn't exist in the long run. I'd much rather make > the eventual goal be to get rid of 'read/write' entirely in favour of > the 'iter' things, but what I absolutely do *NOT* want to see is to > make a _third_ interface for reading and writing. Quite the reverse. > We should strive to make it a _single_ interface, not add a new one. Completele agreement on this. I actually hate the new fops, and only added them reluctantly as I mis-interpreted what you said.