From: Jan Kara Subject: Re: Online defragmentation and ext4migrate Date: Mon, 21 May 2007 12:42:03 +0200 Message-ID: <20070521104203.GC29416@atrey.karlin.mff.cuni.cz> References: <464DA4ED.9040408@linux.vnet.ibm.com> <1179519594.6109.40.camel@eric-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Eric , linux-ext4 To: Aneesh Kumar Return-path: Received: from atrey.karlin.mff.cuni.cz ([195.113.31.123]:39938 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756383AbXEUKmE (ORCPT ); Mon, 21 May 2007 06:42:04 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org > On 5/19/07, Eric wrote: > >On Fri, 2007-05-18 at 18:36 +0530, Aneesh Kumar K.V wrote: > >> The reason why i am asking this is to understand the > >> usefulness of doing a ext4migrate followed by defrag. > >> [...] > >> Also looking at the version 0.4 I see that defrag ioctl only work if we > >> have EXT4_EXTENTS_FL flag set. > > > >ext4migrate is necessary because the current ext4 defrag routines will > >only defragment files stored as extents. AFAIK, converting a file to > >extents does not allow the defrag routine to defragment it "better" than > >an indirect block map inode, but converting any file to extents has > >performance benefits regardless of whether it is later defragmented. > > > >> What are the plans for making defrag work > >> with indirect block map inode ? > > > >I think there is a second set of patches to defragment non-extent > >files. > > > > I was looking at this and didn't find the changes needed to defrag the > non extent files. > > http://www.mail-archive.com/linux-ext4@vger.kernel.org/msg01522.html I've written a patch that defragments non-extent files but after discussion with XFS guys I've decided that the interfaces should be made more generic, so that XFS and other filesystems can use them too... Honza -- Jan Kara SuSE CR Labs