Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261567AbUCVAZM (ORCPT ); Sun, 21 Mar 2004 19:25:12 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261576AbUCVAZM (ORCPT ); Sun, 21 Mar 2004 19:25:12 -0500 Received: from x35.xmailserver.org ([69.30.125.51]:26499 "EHLO x35.xmailserver.org") by vger.kernel.org with ESMTP id S261567AbUCVAZD (ORCPT ); Sun, 21 Mar 2004 19:25:03 -0500 X-AuthUser: davidel@xmailserver.org Date: Sun, 21 Mar 2004 16:25:31 -0800 (PST) From: Davide Libenzi X-X-Sender: davide@bigblue.dev.mdolabs.com To: "Eric W. Biederman" cc: =?iso-8859-1?q?J=F6rn?= Engel , "Patrick J. LoPresti" , Linux Kernel Mailing List Subject: Re: [PATCH] cowlinks v2 In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1760 Lines: 40 On 21 Mar 2004, Eric W. Biederman wrote: > J?rn Engel writes: > > > On Sun, 21 March 2004 09:59:39 -0800, Davide Libenzi wrote: > > > > > > When I did that, fumes of an in-kernel implementation invaded my head for > > > a little while. Then you start thinking that you have to teach apps of new > > > open(2) semantics, you have to bloat kernel code a little bit and you have > > > to deal with a new set of errors cases that open(2) is not expected to > > > deal with. A fully userspace implementation did fit my needs at that time, > > > even if the LD_PRELOAD trick might break if weak aliases setup for open > > > functions change inside glibc. > > > > 209 fairly simple lines definitely have more appear than a full > > in-kernel implementation with many new corner-cases, yes. But it > > looks as if you ignore the -ENOSPC case, so you cheated a little. ;) > > > > No matter how you try, there is no way around an additional return > > code for open(), so we have to break compatibility anyway. The good > > news is that a) people not using this feature won't notice and b) all > > programs I tried so far can deal with the problem. Vim even has a > > decent error message - as if my patch was anticipated already. > > Actually there is... You don't do the copy until an actual write occurs. > Some files are opened read/write when there is simply the chance they might > be written to so delaying the copy is generally a win. What about open+mmap? - Davide - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/