Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755160Ab1CAB1n (ORCPT ); Mon, 28 Feb 2011 20:27:43 -0500 Received: from mail-vx0-f174.google.com ([209.85.220.174]:41250 "EHLO mail-vx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753228Ab1CAB1m convert rfc822-to-8bit (ORCPT ); Mon, 28 Feb 2011 20:27:42 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=NX0LVajE4LpNAYPsETyP29q33fbq9fkrV9c533rQ2RmHSx1GpJaGcL6FSNY7O9hDT4 z2UBRZf+AL8C37D2GaY1Xym47dvy/2xSWgUZQPYK0YjqEGovnw/ereWi5dDBCo8H5/xj 4mrGK3GftsptTMJrZ/fwi8eo7j6cJX6RtErcU= MIME-Version: 1.0 In-Reply-To: <4D6BBCA2.8030104@redhat.com> References: <20110228131118.GA18193@dhcp231-156.rdu.redhat.com> <4D6BBCA2.8030104@redhat.com> Date: Tue, 1 Mar 2011 09:27:40 +0800 Message-ID: Subject: Re: ext2/3/4: punch support? From: Dave Young To: Eric Sandeen Cc: Josef Bacik , Theodore Tso , linux-ext4@vger.kernel.org, Linux Kernel Mailing List , Andrew Morton Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2050 Lines: 61 On Mon, Feb 28, 2011 at 11:17 PM, Eric Sandeen wrote: > On 2/28/11 8:29 AM, Dave Young wrote: >> On Mon, Feb 28, 2011 at 9:11 PM, Josef Bacik wrote: >>> On Mon, Feb 28, 2011 at 03:03:40PM +0800, Dave Young wrote: >>>> Hi, josef and ext guys >>>> >>>> Do you have any plan with ext4 hole punching support? And the >>>> fallocate for ext2/3? >>>> >>>> What's the obstacle to work on this? could someone tell the status of >>>> this issue? >>> >>> There is no obstacle, just nobody has bothered to do it.  If you want to do it >>> go for it.  Thanks, >> >> Yes, I want to do some kvm image space discard stuff, >> I use ext4 as my filesystem, but currently only xfs support something >> like trim/discard. > > As Lukas said, ext4 & ext3 support various forms of trim/discard already. > > But that's different from punch... Lukas and Eric, thanks for pointing out, I think I means punch, although trim/discard is useful as well in guest side. > > And as for fallocate on ext3, you need somewhere to put the metadata to indicate a block is allocated but not written.  This was a lot more straightforward for ext4, since it describes a large range of blocks with a single extent structure. As for ext3 fallocate, I found some interesting discuss: http://www.mail-archive.com/linux-ext4@vger.kernel.org/msg02371.html Andrew, do you know what's the status of above issue? > > -Eric > >> I know general knowledge about ext filesystem, but nearly new to ext4 code, >> could you give some hint where to start? >> >> -- >> Thanks >> dave >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at  http://vger.kernel.org/majordomo-info.html > > -- Regards dave -- 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/