From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751434Ab0GQEOs (ORCPT ); Sat, 17 Jul 2010 00:14:48 -0400 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 ); Sat, 17 Jul 2010 00:14:46 -0400 X-Sasl-enc: h9oDaSS+faql183NF5izo7siXUEkeDkfEMx2iEo7RR1q 1279340082 Subject: Re: [PATCH 07/38] whiteout: Set S_OPAQUE inode flag when creating directories From: Ian Kent To: Valerie Aurora Cc: Alexander Viro , Miklos Szeredi , Jan Blunck , Christoph Hellwig , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org In-Reply-To: <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> <20100716201258.GB21201@shell> Content-Type: text/plain; charset="UTF-8" Date: Sat, 17 Jul 2010 12:14:36 +0800 Message-ID: <1279340076.2973.0.camel@localhost> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 (2.28.3-1.fc12) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@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 > > > > > > 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