From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755301Ab0IWNS7 (ORCPT ); Thu, 23 Sep 2010 09:18:59 -0400 Received: from borg.medozas.de ([188.40.89.202]:39062 "EHLO borg.medozas.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752604Ab0IWNS6 (ORCPT ); Thu, 23 Sep 2010 09:18:58 -0400 Date: Thu, 23 Sep 2010 15:18:57 +0200 (CEST) From: Jan Engelhardt To: Neil Brown cc: Miklos Szeredi , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, vaurora@redhat.com, viro@zeniv.linux.org.uk, jblunck@suse.de, hch@infradead.org Subject: Re: [PATCH 0/5] hybrid union filesystem prototype In-Reply-To: Message-ID: References: <20100826183340.027591901@szeredi.hu> <20100827170551.19616048@notabene> <20100827213502.31af4a4c@notabene> <20100829144207.4fbf2713@notabene> <20100902233200.586fcb31@notabene> User-Agent: Alpine 2.01 (LNX 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On ??, Miklos Szeredi wrote: On Thursday 2010-09-02 16:25, Jan Engelhardt wrote: >> >>There ought to be a reason that other implementations offer >>doing multiple branches with a single vfsmount. > >overdesign However, those implementations offer changing the branch configuration on the fly, e.g. pulling "out" a branch in the middle. With "two-branches only" overlayfs, a multi-branch layout would be multiple vfsmounts describable by something like "(((a b) c) d)". Say you want to remove branch B. (Supposedly) works today in aufs/unionfs. How do you pull it off with overlayfs? You can't umount the (a b) vfsmount because it is used by c.