From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261520AbVFZEcu (ORCPT ); Sun, 26 Jun 2005 00:32:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261524AbVFZEct (ORCPT ); Sun, 26 Jun 2005 00:32:49 -0400 Received: from rwcrmhc12.comcast.net ([216.148.227.85]:14542 "EHLO rwcrmhc12.comcast.net") by vger.kernel.org with ESMTP id S261520AbVFZEcM (ORCPT ); Sun, 26 Jun 2005 00:32:12 -0400 Message-ID: <42BE2FCF.9010705@namesys.com> Date: Sat, 25 Jun 2005 21:32:15 -0700 From: Hans Reiser User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.5) Gecko/20041217 X-Accept-Language: en-us, en MIME-Version: 1.0 To: David Masover CC: Valdis.Kletnieks@vt.edu, Horst von Brand , Jeff Garzik , Christoph Hellwig , Andrew Morton , linux-kernel@vger.kernel.org, ReiserFS List Subject: Re: reiser4 plugins References: <200506240241.j5O2f1eb005609@laptop11.inf.utfsm.cl> <42BCD93B.7030608@slaphack.com> <200506251420.j5PEKce4006891@turing-police.cc.vt.edu> <42BDA377.6070303@slaphack.com> <200506252031.j5PKVb4Y004482@turing-police.cc.vt.edu> <42BE1D9A.80006@slaphack.com> In-Reply-To: <42BE1D9A.80006@slaphack.com> X-Enigmail-Version: 0.90.1.0 X-Enigmail-Supports: pgp-inline, pgp-mime Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Think of reiser4 as being designed to be 90% library routines, and 10% program. Now, can these libraries be used by other filesystems? Why yes, some can. How many of them should be used by other filesystems? Reality: few people are going to rewrite their existing filesytems to mostly use our code. However, people writing new filesystems, if we have done our job right, will decide that our code is the easiest code base to use for implementing whatever differentiates them while avoiding reinventing what they don't seek to be better at. Detail: Regarding our allocation and balance and compress and encrypt at flush time code, unless your filesystem is also based on balanced trees it might be the least reusable code in the filesystem. It is the hardest code in the filesystem, because the algorithms we implemented were simply hard. Number one task for me, after we go in and I can stop dealing with prerequisites to inclusion, is to review the vm interaction from beginning to end one more time (and kill the emergency flush code). Good part: if you want to implement new filesystem semantics, our storage layer is more suitable for your innovating on top of than any other. Less work to code it, more functionality and flexibility, plugins are great for hacking on top of. The storage layer is very very high performance, and if semantics are your focus, using our storage layer is likely to be a good choice because it is well abstracted and works without understanding what it works on. For example, you can invent new items for the tree to balance (e.g. new directory entry formats), and all you have to do is write an item handler for the item and you don't have to touch the balancing code. In general, if a new filesystem can do some narrow aspect better than our existing library routine, it should do its aspect using its innovative new code, and where it is not trying to be better than us, it can reuse our code more easily than any alternative. Many people who would write a new filesystem from scratch, can, if they use our code base, accomplish their objectives with just writing some new plugins and contributing them to the collection. Others can define a new filesystem to consist of a particular configuration of plugins and glue that are what you get when you mount fubarfs. We would be happy to accomodate that by creating subdirectories for different flavorings of reiser4 to live in. Because our code is 90% library routines (aka plugins), eliminating the plugin layer is like eliminating main() in a user space program. Hans David Masover wrote: > Actually, I'll have to go back on this a bit. There are different kinds > of plugins, and I'm not sure exactly which people want in the VFS. This > may be because nobody's said that, though. > > Still, while plugins may not depend on Reiser, Reiser depends on plugins. > >