Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758236AbXF3LNv (ORCPT ); Sat, 30 Jun 2007 07:13:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755798AbXF3LNn (ORCPT ); Sat, 30 Jun 2007 07:13:43 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:43467 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755770AbXF3LNm (ORCPT ); Sat, 30 Jun 2007 07:13:42 -0400 Date: Sat, 30 Jun 2007 12:13:40 +0100 From: Christoph Hellwig To: Jeff Garzik Cc: Christoph Hellwig , Nick Piggin , Linux Kernel Mailing List , Linux Memory Management List , linux-fsdevel@vger.kernel.org, Andrew Morton Subject: Re: [RFC] fsblock Message-ID: <20070630111340.GA24946@infradead.org> Mail-Followup-To: Christoph Hellwig , Jeff Garzik , Nick Piggin , Linux Kernel Mailing List , Linux Memory Management List , linux-fsdevel@vger.kernel.org, Andrew Morton References: <20070624014528.GA17609@wotan.suse.de> <467DE00A.9080700@garzik.org> <20070630104244.GC24123@infradead.org> <46863A23.2010001@garzik.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <46863A23.2010001@garzik.org> User-Agent: Mutt/1.4.2.3i X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1110 Lines: 25 On Sat, Jun 30, 2007 at 07:10:27AM -0400, Jeff Garzik wrote: > >Not really, the current behaviour is a bug. And it's not actually buffer > >layer specific - XFS now has a fix for that bug and it's generic enough > >that everyone could use it. > > I'm not sure I follow. If you require block allocation at mmap(2) time, > rather than when a page is actually dirtied, you are denying userspace > the ability to do sparse files with mmap. > > A quick Google readily turns up people who have built upon the > mmap-sparse-file assumption, and I don't think we want to break those > assumptions as a "bug fix." > > Where is the bug? It's not mmap time but page dirtying time. Currently the default behaviour is not to allocate at page dirtying time but rather at writeout time in some scenarious. (and s/allocation/reservation/ applies for delalloc of course) - 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/