From: Joel Becker Subject: Re: e4defrag and immutable files Date: Tue, 8 Jun 2010 18:10:28 -0700 Message-ID: <20100609011028.GD6795@mail.oracle.com> References: <4C002427.3010706@zytor.com> <4C05604D.2070401@oracle.com> <20100601194924.GF4426@thunk.org> <4C06083B.7050102@zytor.com> <4C069CAA.50304@oracle.com> <4C0EC034.6010603@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Sunil Mushran , tytso@mit.edu, linux-ext4@vger.kernel.org, Mark Fasheh To: "H. Peter Anvin" Return-path: Received: from rcsinet10.oracle.com ([148.87.113.121]:43130 "EHLO rcsinet10.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751810Ab0FIBLs (ORCPT ); Tue, 8 Jun 2010 21:11:48 -0400 Content-Disposition: inline In-Reply-To: <4C0EC034.6010603@zytor.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Tue, Jun 08, 2010 at 03:12:04PM -0700, H. Peter Anvin wrote: > On 06/02/2010 11:02 AM, Sunil Mushran wrote: > > "Immutable" means the contents do not change. But the file mappings > > could change. > > > > "Fixed mapping" means the mappings do not change but contents > > could (as long as the ondisk mappings don't). > > > > "Fixed metadata" means the entire inode (mappings included) cannot > > change but the contents could (as long as the ondisk mappings don't). > > (This does have the side effect of allowing writes without touching the > > mtime. Like XFS' invisible i/o.) > > > > Actually, if you're going to have three flags you might as well make > them orthogonal. That is, separate "fixed contents", "fixed mappings", > "fixed metadata" -- and don't consider the mapping as metadata for this > purpose. I think Sunil was defining terms, not suggesting three flags ;-) That said, it does allow all the possible characteristics in the discussion. The only ugly think I can see is that we'll have three new flags, plus the old immutable flag that means the same as setting all three new flags. Joel -- "But all my words come back to me In shades of mediocrity. Like emptiness in harmony I need someone to comfort me." Joel Becker Principal Software Developer Oracle E-mail: joel.becker@oracle.com Phone: (650) 506-8127