From mboxrd@z Thu Jan 1 00:00:00 1970 From: Goswin von Brederlow Subject: Re: [fuse-devel] delta filesystem prototype Date: Tue, 03 Mar 2009 11:59:20 +0100 Message-ID: <87r61ec1o7.fsf@frosties.localdomain> References: <9884.1236069117@jrobl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Miklos Szeredi , linux-fsdevel@vger.kernel.org, fuse-devel@lists.sourceforge.net To: hooanon05@yahoo.co.jp Return-path: Received: from fmmailgate03.web.de ([217.72.192.234]:45286 "EHLO fmmailgate03.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750711AbZCCK7X (ORCPT ); Tue, 3 Mar 2009 05:59:23 -0500 In-Reply-To: <9884.1236069117@jrobl> (hooanon's message of "Tue, 03 Mar 2009 17:31:57 +0900") Sender: linux-fsdevel-owner@vger.kernel.org List-ID: hooanon05@yahoo.co.jp writes: > Miklos Szeredi: >> Here is my first try at a "delta" filesystem. It takes two > ::: >> Comments, bug reports are welcome. > > As I wrote before, it is unclear how do you implment mmap. > I am afrid you need to copyup the entire file to support MAP_SHARED. Why? When a page is accessed the filesystem gets a read request and reads it either from the RO branch or the delta branch. Why should it need to copy up the full file? MfG Goswin