From: Josef Sipek Subject: Re: [RFC][PATCH] Secure Deletion and Trash-Bin Support for Ext4 Date: Wed, 6 Dec 2006 19:56:19 -0500 Message-ID: <20061207005619.GA12320@filer.fsl.cs.sunysb.edu> References: <20061204235042.GS33919298@melbourne.sgi.com> <20061206091100.GA33919298@melbourne.sgi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Nikolai Joukov , linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org Return-path: Received: from filer.fsl.cs.sunysb.edu ([130.245.126.2]:48107 "EHLO filer.fsl.cs.sunysb.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S937871AbWLGA43 (ORCPT ); Wed, 6 Dec 2006 19:56:29 -0500 To: David Chinner Content-Disposition: inline In-Reply-To: <20061206091100.GA33919298@melbourne.sgi.com> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Wed, Dec 06, 2006 at 08:11:00PM +1100, David Chinner wrote: > They are defined but unused in 2.6.19, right? I can't see anywhere > in the 2.6.19 ext2/3/4/reiser trees that actually those flags, > including setting and retrieving them from disk. JFS i can see > sets, clears and retreives them, but not the fielsystems you > mention. Though I might just be blind..... ;) > > If all we need to add to XFS is support for those flags, then XFS > support would be trivial to add. > > Oh, damn. I take that back. We're almost out of flag space in the on > disk inode - these two flags would use the last 2 flag bits so this > may require an on disk inode format change in XFS. This will be > a little more complex than I first thought, but not impossible > as we already support two on-disk inode format versions. Hrm. I was toying around with the idea of using a flag to mark inodes as whiteouts (similar to what BSD does) for Unionfs. I remember that Jan Blunck tried similar thing in his implementation of VFS unionfs mounts. I am not entirely convinced that whiteout inode flag is the right way to do things, but I'm just raising this now as I wouldn't want to wait for new ondisk format for XFS to say that Unionfs supports XFS. (Assuming that it is the right approach.) ;-) Josef "Jeff" Sipek. -- I already backed up the box once, I can do it again!