From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966146Ab0GPUNS (ORCPT ); Fri, 16 Jul 2010 16:13:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:8011 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759208Ab0GPUNQ (ORCPT ); Fri, 16 Jul 2010 16:13:16 -0400 Date: Fri, 16 Jul 2010 16:12:58 -0400 From: Valerie Aurora To: Ian Kent Cc: Alexander Viro , Miklos Szeredi , Jan Blunck , Christoph Hellwig , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH 07/38] whiteout: Set S_OPAQUE inode flag when creating directories Message-ID: <20100716201258.GB21201@shell> References: <1276627208-17242-1-git-send-email-vaurora@redhat.com> <1276627208-17242-8-git-send-email-vaurora@redhat.com> <20100713040555.GB3949@zeus.themaw.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100713040555.GB3949@zeus.themaw.net> User-Agent: Mutt/1.4.2.2i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 13, 2010 at 12:05:56PM +0800, Ian Kent wrote: > On Tue, Jun 15, 2010 at 11:39:37AM -0700, Valerie Aurora wrote: > > From: Jan Blunck > > > > In case of an union directory we don't want that the directories on lower > > layers of the union "show through". So to prevent that the contents of > > underlying directories magically shows up after a mkdir() we set the S_OPAQUE > > flag if directories are created where a whiteout existed before. > > I found this hard to understand. > > Do you mean: > > For directories within a union that are whiteouts we don't want the entries of > lower layer file system to "show through". To achieve this we set the S_OPAQUE > flag after a mkdir() on directories that are whiteouts. That is much clearer. I ended up with this version, what do you think? whiteout: Set opaque flag if new directory was previously a whiteout If we mkdir() a directory on the top layer of a union, we don't want entries from a matching directory on the lower layer to "show through" suddenly. To prevent this, we set the opaque flag on a directory if there was previously a white-out with the same name. (If there is no white-out and the directory exists in a lower layer, then mkdir() will fail with EEXIST.) -VAL