From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH 01/24] Unionfs: Documentation Date: Tue, 9 Jan 2007 09:53:45 +0000 Message-ID: <20070109095345.GB12406@infradead.org> References: <20070108140224.3a814b7d.akpm@osdl.org> <200701090003.l0903Z2O017720@agora.fsl.cs.sunysb.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Andrew Morton , Shaya Potter , Josef 'Jeff' Sipek , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, hch@infradead.org, viro@ftp.linux.org.uk, torvalds@osdl.org, mhalcrow@us.ibm.com, David Quigley Return-path: Received: from pentafluge.infradead.org ([213.146.154.40]:43378 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751256AbXAIJxw (ORCPT ); Tue, 9 Jan 2007 04:53:52 -0500 To: Erez Zadok Content-Disposition: inline In-Reply-To: <200701090003.l0903Z2O017720@agora.fsl.cs.sunysb.edu> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Mon, Jan 08, 2007 at 07:03:35PM -0500, Erez Zadok wrote: > However, I must caution that a file system like ecryptfs is very different > from Unionfs, the latter being a fan-out file system---and both have very > different goals. The common code between the two file systems, at this > stage, is not much (and we've already extracted some of it into the "stackfs > layer"). I think that's an very important point. We have a chance to get that non-fanout filesystems right quite easily - something I wished that would have been done before the ecryptfs merge - while getting fan-out stackable filesystems is a really hard task. In addition to that I know exactly one fan-out stackable filesystem that is posisbly useful, which is unionfs. Because of that I'm much more inclined to add VFS asistance for this particular problem (unioning) instead of adding complex infrastructure to solve a general problem that people don't benefit from.