From: Andreas Dilger Subject: Re: [Ext4 punch hole 1/5] Ext4 Punch Hole Support: Convert Blocks to Uninit Exts Date: Wed, 2 Mar 2011 17:56:52 -0700 Message-ID: <4CB90DB0-DA5C-4A64-9DC0-53F46BE40915@dilger.ca> References: <4D6C6318.2010105@linux.vnet.ibm.com> <02A57041-5FC1-419D-89D2-47D541616DD4@dilger.ca> <20110302202313.GA15097@dastard> Mime-Version: 1.0 (iPhone Mail 8C148a) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8BIT Cc: Allison Henderson , "linux-ext4@vger.kernel.org" To: Dave Chinner Return-path: Received: from shawmail.shawcable.com ([64.59.128.220]:35242 "EHLO mail.shawcable.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752551Ab1CCA45 convert rfc822-to-8bit (ORCPT ); Wed, 2 Mar 2011 19:56:57 -0500 In-Reply-To: <20110302202313.GA15097@dastard> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 2011-03-02, at 13:23, Dave Chinner wrote: > On Mon, Feb 28, 2011 at 11:42:48PM -0700, Andreas Dilger wrote: >> On 2011-02-28, at 8:08 PM, Allison Henderson wrote: >>> This first patch adds a function to convert a range of blocks >>> to an uninitialized extent. This function will >>> be used to first convert the blocks to extents before >>> punching them out. >> >> This was proposed as a separate function for FALLOCATE by Dave >> Chinner (based on XFS_IOC_ZERO_RANGE), so this is useful as a >> standalone function. > > XFS_IOC_ZERO_RANGE converts a range to unwritten extents, not > uninitialised extents. An uninitialised extent is one that is > allocated but had not data written to it (i.e. contains stale data), > while an unwritten/preallocated extent is guaranteed to contain > zeros. For ext4 at least there is no distinction at least. Still, it is good to use the right terms so that we are all on the same page. > This may be just a terminology issue, but we should try to > use the same jargon across all filesystems... Cheers, Andreas