From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261444AbUCAVki (ORCPT ); Mon, 1 Mar 2004 16:40:38 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261450AbUCAVkh (ORCPT ); Mon, 1 Mar 2004 16:40:37 -0500 Received: from s2.ukfsn.org ([217.158.120.143]:63445 "EHLO mail.ukfsn.org") by vger.kernel.org with ESMTP id S261444AbUCAVkZ (ORCPT ); Mon, 1 Mar 2004 16:40:25 -0500 Subject: Re: Ibm Serveraid Problem with 2.4.25 From: Alan Swanson To: linux-kernel@vger.kernel.org Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-9CgXedFZTxpHHD06zT8Z" Message-Id: <1078177104.7677.6.camel@zeus.local> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.5 Date: Mon, 01 Mar 2004 21:38:25 +0000 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --=-9CgXedFZTxpHHD06zT8Z Content-Type: text/plain Content-Transfer-Encoding: quoted-printable Marcelo Tosatti wrote: > On Mon, 1 Mar 2004, Chuck Lever wrote: > > > hi marcelo- > > > > your "fix" will break readahead again for NFS. with the ">=3D" as you > > propose, the read ahead code will never be able to read the last page o= f > > the file as a coalesced read, it will always be a separate 4KB read. > >=20 > > the problem is not the readahead code, it is the driver code that tries > > to read beyond the end of the device. my change merely exposed this > > misbehavior. > > > > so there is a broken assumption somewhere about how the index of the la= st > > page of a file/device is computed. i think it is a problem when the fi= le > > ends exactly on a page boundary. > > > > alain, if you don't use the NFS client, marcelo's fix should work just > > fine for you. but i believe that in general it is incorrect. > > Okey, most drivers do no exhibit this problem indeed. > > We should try to fix the problematic drivers, then. > > If we can't do it easily and in a straightforward manner, I'm afraid we > will have to undo your change because even if the "read end beyond of > device" accesses are harmless (are they really harmless?), they must > fixed. > > Agreed? > > I'll take a look at them later today, but I'm no expert, so help is very > appreciated. > > We know that these have problems: > > - Promise ATA > - ips (serveraid) Also seeing this with the siimage driver with a 3112 SATA chipset. --=20 Alan. "One must never be purposelessnessnesslessness." --=-9CgXedFZTxpHHD06zT8Z Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.2 (GNU/Linux) iD8DBQBAQ61QagoW53DrKMIRAosDAKCJVbg+ATjv/pEq6DKY5mJ3yNiTEQCgsQUr lLfqoam2m7glclGNVV08RAw= =u/16 -----END PGP SIGNATURE----- --=-9CgXedFZTxpHHD06zT8Z--