Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758969Ab0DHTim (ORCPT ); Thu, 8 Apr 2010 15:38:42 -0400 Received: from 0122700014.0.fullrate.dk ([95.166.99.235]:57084 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757316Ab0DHTik (ORCPT ); Thu, 8 Apr 2010 15:38:40 -0400 Date: Thu, 8 Apr 2010 21:38:38 +0200 From: Jens Axboe To: Tvrtko Ursulin Cc: Nikanth Karthikesan , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] loop: Update mtime when writing using aops Message-ID: <20100408193838.GY10103@kernel.dk> References: <201004081551.37824.knikanth@suse.de> <20100408124539.GM10103@kernel.dk> <201004081515.56161.tvrtko.ursulin@sophos.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201004081515.56161.tvrtko.ursulin@sophos.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1367 Lines: 34 On Thu, Apr 08 2010, Tvrtko Ursulin wrote: > On Thursday 08 April 2010 13:45:39 Jens Axboe wrote: > > On Thu, Apr 08 2010, Nikanth Karthikesan wrote: > > > Update mtime when writing to backing filesystem using the address space > > > operations write_begin and write_end. > > > > You forgot to include a 'why' :-) > > > > Not that I disagree with the patch, just curious what made you make the > > change. > > You mean how the bug was found? I originally reported this problem against > openSUSE 11.2 kernel, where when you have a dm-crypt loop filesystem the > container file modification time does not get updated with use. Consequence > of that is that backup runs would miss the fact container has changed. > > Maybe one could argue it is a security feature in this scenario :), but as the > problem turns out to be unrelated to the crypto case, rather contained in the > loop driver itself, it looks like that would not hold. :-) I suppose you could update the mtime on tear down, since then it would also be safe to actually backup. But same difference in the end I suppose, I'll add the patch. -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/