From: Russell Cattelan Subject: Re: [RFC] Ext3 online defrag Date: Tue, 24 Oct 2006 15:31:08 -0500 Message-ID: <1161721868.29094.35.camel@xenon.msp.redhat.com> References: <20061023122710.GA12034@atrey.karlin.mff.cuni.cz> <20061023141641.GA29649@thunk.org> <20061024041433.GB12506@havoc.gtf.org> <20061024135928.GB11034@melbourne.sgi.com> <20061024194416.GB16087@thunk.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-ReSBdGW5mPuoFvtWApCO" Cc: David Chinner , Jeff Garzik , Alex Tomas , Jan Kara , linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org Return-path: Received: from cattelan-host202.dsl.visi.com ([208.42.117.202]:8408 "EHLO slurp.thebarn.com") by vger.kernel.org with ESMTP id S1161114AbWJXUcs (ORCPT ); Tue, 24 Oct 2006 16:32:48 -0400 To: Theodore Tso In-Reply-To: <20061024194416.GB16087@thunk.org> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org --=-ReSBdGW5mPuoFvtWApCO Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Tue, 2006-10-24 at 15:44 -0400, Theodore Tso wrote: > On Tue, Oct 24, 2006 at 11:59:28PM +1000, David Chinner wrote: > > That's the wrong way to look at it. if you want the userspace > > process to specify a location, then you should preallocate it first > > before doing anything else. There is no need to clutter a simple > > data mover interface with all sorts of unnecessary error handling. >=20 > This is doable, but it adds a huge amount of complexity before we > could implement on-line defragmentation. >=20 > First of all, we would need a way of allowing userpsace to specify > which blocks should be used in the preallocation. >=20 > Secondly, we would need a way of marking blocks as "preallocated but > not pre-zeroed"; otherwise we would have to zero out all of the blocks > in order to assure security (don't want userspace programs seeing the > previous contents of the data blocks), only to do the copy and the > extents vector swap Chris Mason page place holder work for DIRECT IO should be applicable to any pre-allocations? --=20 Russell Cattelan --=-ReSBdGW5mPuoFvtWApCO Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (GNU/Linux) iD8DBQBFPngMNRmM+OaGhBgRAs/xAJ0TspiyKdljn3HKa7UBmD+lQDHqeACcD6KM Sth36VIh+T+Uq5ThpcASWak= =H5Mh -----END PGP SIGNATURE----- --=-ReSBdGW5mPuoFvtWApCO--