Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753325Ab1F3MoT (ORCPT ); Thu, 30 Jun 2011 08:44:19 -0400 Received: from mail-bw0-f46.google.com ([209.85.214.46]:63433 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751159Ab1F3MoP (ORCPT ); Thu, 30 Jun 2011 08:44:15 -0400 From: Miklos Szeredi To: David Howells Cc: Ric Wheeler , Michal Suchanek , Alexander Viro , Ian Kent , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Jeff Moyer , Christoph Hellwig Subject: Re: Union mount and overlayfs bake off? References: <4E0AF2BA.2040706@gmail.com> <1302756608.2854.10.camel@perseus.themaw.net> <4DA4B6A8.7030804@gmail.com> <4DA5DCB8.3040101@gmail.com> <4DA5F569.9020309@gmail.com> <24792.1302808448@redhat.com> <2477.1309342656@redhat.com> Date: Thu, 30 Jun 2011 14:44:59 +0200 In-Reply-To: <2477.1309342656@redhat.com> (David Howells's message of "Wed, 29 Jun 2011 11:17:36 +0100") Message-ID: <87vcvnpjxw.fsf@tucsk.pomaz.szeredi.hu> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.2 (gnu/linux) 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 Content-Length: 971 Lines: 26 David Howells writes: > I've been dealing with some of Al's issues with the unionmount > patches, but I know he's got more - I just can't remember them all. A couple of questions I have: 1) What happens to the union in a cloned namespace (CLONE_NEWNS)? 2) What's the overhead for non-unioned filesystems if CONFIG_UNION_MOUNTS is enabled? Does it show up in any microbenchmarks? 3) Is there a future strategy for making atomic operations really atomic? E.g. what happens if power is lost in the middle of a copy-up? Or if whiteout of source fails after a successful rename()? 4) Have you looked at overlayfs? Do you have any thoughts about the relative merrits of each solution? Thanks, Miklos -- 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/