From: Goswin von Brederlow Subject: Re: zero out blocks of freed user data for operation a virtual machine environment Date: Mon, 25 May 2009 15:14:02 +0200 Message-ID: <87ab51qq91.fsf@frosties.localdomain> References: <20090524170045.GC24753@cip.informatik.uni-erlangen.de> <20090524101551.57b706e9@infradead.org> <20090524173933.GD24753@cip.informatik.uni-erlangen.de> <20090525120320.GA25908@mit.edu> <20090525123430.GA5534@cip.informatik.uni-erlangen.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Theodore Tso , Arjan van de Ven , tytso@thunk.org, LKML , linux-ext4@vger.kernel.org To: Thomas Glanzmann Return-path: Received: from fmmailgate01.web.de ([217.72.192.221]:57405 "EHLO fmmailgate01.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751746AbZEYNOC (ORCPT ); Mon, 25 May 2009 09:14:02 -0400 In-Reply-To: <20090525123430.GA5534@cip.informatik.uni-erlangen.de> (Thomas Glanzmann's message of "Mon, 25 May 2009 14:34:30 +0200") Sender: linux-ext4-owner@vger.kernel.org List-ID: Thomas Glanzmann writes: > Hello Ted, > >> Yes, it does, sb_issue_discard(). So if you wanted to hook into this >> routine with a function which issued calls to zero out blocks, it >> would be easy to create a private patch. > > that sounds good because it wouldn't only target the most used > filesystem but every other filesystem that uses the interface as well. > Do you think that a tunable or configurable patch has a chance to hit > upstream as well? > > Thomas I could imagine a device mapper target that eats TRIM commands and writes out zeroes instead. That should be easy to maintain outside or inside the upstream kernel source. MfG Goswin