Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750734AbXAHX35 (ORCPT ); Mon, 8 Jan 2007 18:29:57 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750729AbXAHX35 (ORCPT ); Mon, 8 Jan 2007 18:29:57 -0500 Received: from filer.fsl.cs.sunysb.edu ([130.245.126.2]:52230 "EHLO filer.fsl.cs.sunysb.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750722AbXAHX34 (ORCPT ); Mon, 8 Jan 2007 18:29:56 -0500 Date: Mon, 8 Jan 2007 18:25:16 -0500 From: Josef Sipek To: Andrew Morton Cc: 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 , Erez Zadok Subject: Re: [PATCH 01/24] Unionfs: Documentation Message-ID: <20070108232516.GB1269@filer.fsl.cs.sunysb.edu> References: <1168229596580-git-send-email-jsipek@cs.sunysb.edu> <1168229596875-git-send-email-jsipek@cs.sunysb.edu> <20070108111852.ee156a90.akpm@osdl.org> <20070108131957.cbaf6736.akpm@osdl.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070108131957.cbaf6736.akpm@osdl.org> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1263 Lines: 33 On Mon, Jan 08, 2007 at 01:19:57PM -0800, Andrew Morton wrote: ... > If it's not in the changelog or the documentation, it doesn't exist. Good point. I'll add it for next time. > > It's the same thing as modifying a block > > device while a file system is using it. Now, when unionfs gets confused, > > it shouldn't oops, but would one expect ext3 to allow one to modify its > > backing store while its using it? > > There's no such problem with bind mounts. It's surprising to see such a > restriction with union mounts. Bind mounts are a purely VFS level construct. Unionfs is, as the name implies, a filesystem. Last year at OLS, it seemed that a lot of people agreed that unioning is neither purely a fs construct, nor purely a vfs construct. I'm using Unionfs (and ecryptfs) as guinea pigs to make linux fs stacking friendly - a topic to be discussed at LSF in about a month. Josef "Jeff" Sipek. -- Computer Science is no more about computers than astronomy is about telescopes. - Edsger Dijkstra - 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/