From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754661Ab1F2KR5 (ORCPT ); Wed, 29 Jun 2011 06:17:57 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47788 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753284Ab1F2KRz (ORCPT ); Wed, 29 Jun 2011 06:17:55 -0400 Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <4E0AF2BA.2040706@gmail.com> 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> To: Ric Wheeler Cc: dhowells@redhat.com, Michal Suchanek , Alexander Viro , Ian Kent , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Jeff Moyer , miklos@szeredi.hu, Christoph Hellwig Subject: Re: Union mount and overlayfs bake off? Date: Wed, 29 Jun 2011 11:17:36 +0100 Message-ID: <2477.1309342656@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ric Wheeler wrote: > I think that it has been a while since David reposted the refreshed patch set > for union mounts & know that overlayfs has recent updates as well. > > Despite that, I have not seen a lot of feedback from reviewers or testers. The main problem I've got is that it causes lockdep to generate warnings when the top layer and one of the lower layers are of the same filesystem type. The obvious way round this is to give each superblock its own i_mutex lock class rather than putting this in the file_system_type struct, but I'm not sure of the consequences (the two obvious problems are superblock transience and the fact that there may be so many more of them that it may explode lockdep). I've split out some of the VFS patches that we might be interested in taking upstream anyway. They're currently sat on Al's plate for his consideration. 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. David