From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ian Kent <raven@themaw.net>
Subject: Re: [PATCH 07/38] whiteout: Set S_OPAQUE inode flag when creating
 directories
Date: Sat, 17 Jul 2010 12:14:36 +0800
Message-ID: <1279340076.2973.0.camel@localhost>
References: <1276627208-17242-1-git-send-email-vaurora@redhat.com>
	 <1276627208-17242-8-git-send-email-vaurora@redhat.com>
	 <20100713040555.GB3949@zeus.themaw.net>  <20100716201258.GB21201@shell>
Mime-Version: 1.0
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
	Miklos Szeredi <miklos@szeredi.hu>,
	Jan Blunck <jblunck@suse.de>,
	Christoph Hellwig <hch@infradead.org>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
To: Valerie Aurora <vaurora@redhat.com>
Return-path: <linux-fsdevel-owner@vger.kernel.org>
Received: from out1.smtp.messagingengine.com ([66.111.4.25]:34474 "EHLO
	out1.smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK)
	by vger.kernel.org with ESMTP id S1750799Ab0GQEOq (ORCPT
	<rfc822;linux-fsdevel@vger.kernel.org>);
	Sat, 17 Jul 2010 00:14:46 -0400
In-Reply-To: <20100716201258.GB21201@shell>
Sender: linux-fsdevel-owner@vger.kernel.org
List-ID: <linux-fsdevel.vger.kernel.org>

On Fri, 2010-07-16 at 16:12 -0400, Valerie Aurora wrote:
> 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 <jblunck@suse.de>
> > > 
> > > 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.)

That's much clearer IMHO.

> 
> -VAL