From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756129Ab1F2R3s (ORCPT ); Wed, 29 Jun 2011 13:29:48 -0400 Received: from rcsinet10.oracle.com ([148.87.113.121]:19480 "EHLO rcsinet10.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752701Ab1F2R3p (ORCPT ); Wed, 29 Jun 2011 13:29:45 -0400 Message-ID: <4E0B60DE.50908@oracle.com> Date: Wed, 29 Jun 2011 10:29:02 -0700 From: Sunil Mushran User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.17) Gecko/20110516 Lightning/1.0b2 Thunderbird/3.1.10 MIME-Version: 1.0 To: =?ISO-8859-1?Q?P=E1draig_Brady?= CC: Christoph Hellwig , Dave Chinner , Josef Bacik , linux-fsdevel@vger.kernel.org, viro@ZenIV.linux.org.uk, linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org, xfs@oss.sgi.com Subject: Re: [PATCH] xfstests 255: add a seek_data/seek_hole tester References: <1309275199-10801-1-git-send-email-josef@redhat.com> <1309275199-10801-5-git-send-email-josef@redhat.com> <20110629065306.GC1026@dastard> <20110629074021.GA26086@infradead.org> <4E0B019E.8080800@draigBrady.com> In-Reply-To: <4E0B019E.8080800@draigBrady.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Source-IP: rtcsinet22.oracle.com [66.248.204.30] X-CT-RefId: str=0001.0A090209.4E0B60F5.014F:SCFSTAT5015188,ss=1,re=-4.000,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/29/2011 03:42 AM, Pádraig Brady wrote: > There is the argument, that if this interface can distinguish > these dirty unwritten extents, then why can't the fiemap interface too? > The advantage of the fiemap interface is that it can distinguish > empty extents vs holes. Empty extents will become increasingly common > I think, given the fragmentation and space guarantee benefits they give. > It would be cool for cp for example to be able to efficiently copy > empty extents from source to dest. I'm not too sure about that. Atleast not enabled by default. Most users use cp to backup data. Not empty space. In this case, this empty extent may not even be de-dupable. Frankly I'd be happier of cp started to exploited fallocate() to create larger extents before copying data into them. Atleast for the large files.