From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: util-linux-owner@vger.kernel.org Received: from mail5.vodafone.ie ([213.233.128.176]:20505 "EHLO mail5.vodafone.ie" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750984AbaAXBA6 (ORCPT ); Thu, 23 Jan 2014 20:00:58 -0500 Message-ID: <52E1BB47.80609@draigBrady.com> Date: Fri, 24 Jan 2014 01:00:55 +0000 From: =?ISO-8859-1?Q?P=E1draig_Brady?= MIME-Version: 1.0 To: Rodrigo Campos CC: util-linux@vger.kernel.org Subject: Re: drill: Make a file sparse without using extra disk space References: <20140123212813.GE20054@sdfg.com.ar> In-Reply-To: <20140123212813.GE20054@sdfg.com.ar> Content-Type: text/plain; charset=ISO-8859-1 Sender: util-linux-owner@vger.kernel.org List-ID: On 01/23/2014 09:28 PM, Rodrigo Campos wrote: > Hi! > > I've written a small simple tool to make a file sparse without using extra disk > space, it just digs holes on the file when possible. To dig the hole uses the > Linux-specific fallocate(2) syscall with FALLOC_FL_PUNCH_HOLE. So, also, it only > works on some file-systems. > > Do you think that util-linux would be a good place for such a simple, linux-only > program ? The case I see it can be useful is to use on VM images file backed (or > I wrote it with this in mind, at least :)). > > The code is quite simple, it's written in plain C (C99 actually) and doesn't > have any external dependencies. You can see the gitweb here: > > http://sdfg.com.ar/git/?p=drill.git > > or just clone it from: > > git://sdfg.com.ar/drill.git > > > Given that there is a fallocate tool that uses the other mode of fallocate(2) > already, all the detection for fallocate is already there. So it should, I > guess, be easy to integrate to the code-base, adding also the #ifndef > fallocate.c has and that compatibility stuff. > > Also, as you can see in the commits, I just started it some days ago. So if > you think it should have some other feature, or something else, please let me > know :) > > I'm not sure how this work, but I can write a patch against util-linux if you > think it can be added. If you know there is something I should particulary take > into account for that, I will really appreciate if you let me know :) > > > > > Thanks a lot, > Rodrigo > -- > To unsubscribe from this list: send the line "unsubscribe util-linux" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > This functionality is useful. Would it be possible to just add to fallocate with --punch-hole=sparse or something? Also dd has the conv=sparse option, so maybe this functionality can be added there. We're currently discussing that on the GNU coreutils mailing list. thanks, Pádraig.