From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36206) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c6JSh-0006wu-LR for qemu-devel@nongnu.org; Mon, 14 Nov 2016 10:46:24 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1c6JSg-0000Fr-QO for qemu-devel@nongnu.org; Mon, 14 Nov 2016 10:46:23 -0500 References: <8b945cd9-a601-4c81-495f-c1837f8d8231@redhat.com> <20161114095007.GA4755@noname.str.redhat.com> From: Eric Blake Message-ID: <62d2eccd-6399-a23a-cb82-4ceae58228d8@redhat.com> Date: Mon, 14 Nov 2016 09:46:12 -0600 MIME-Version: 1.0 In-Reply-To: <20161114095007.GA4755@noname.str.redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="DxJMTwEsOoSddENjNK6d0F3tA9WnnrBM0" Subject: Re: [Qemu-devel] Assertion failure on qcow2 disk with cluster_size != 64k List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: Ed Swierk , qemu-block@nongnu.org, qemu-devel@nongnu.org, "Denis V. Lunev" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --DxJMTwEsOoSddENjNK6d0F3tA9WnnrBM0 From: Eric Blake To: Kevin Wolf Cc: Ed Swierk , qemu-block@nongnu.org, qemu-devel@nongnu.org, "Denis V. Lunev" Message-ID: <62d2eccd-6399-a23a-cb82-4ceae58228d8@redhat.com> Subject: Re: [Qemu-devel] Assertion failure on qcow2 disk with cluster_size != 64k References: <8b945cd9-a601-4c81-495f-c1837f8d8231@redhat.com> <20161114095007.GA4755@noname.str.redhat.com> In-Reply-To: <20161114095007.GA4755@noname.str.redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 11/14/2016 03:50 AM, Kevin Wolf wrote: > Am 24.10.2016 um 22:32 hat Eric Blake geschrieben: >> On 10/21/2016 08:14 AM, Ed Swierk wrote: >>> On Thu, Oct 20, 2016 at 6:38 PM, Eric Blake wrote= : >>>> On 10/20/2016 07:24 PM, Ed Swierk wrote: >>>>> Changing max_transfer in the normal write case to >>>>> MIN_NON_ZERO(alignment, MAX_WRITE_ZEROES_BOUNCE_BUFFER) appears to = fix >>>>> the problem, but I don't pretend to understand all the subtleties >>>>> here. >>>> >>>> That actually sounds like the right fix. But since the bug was prob= ably >>>> caused by my code, I'll formalize it into a patch and see if I can >>>> modify the testsuite to give it coverage. >>> >>> If alignment > MAX_WRITE_ZEROES_BOUNCE_BUFFER (however unlikely) we >>> have the same problem, so maybe this would be better? >> >> Our qcow2 support is currently limited to a maximum of 2M clusters; >> while MAX_WRITE_ZEROES_BOUNCE_BUFFER is 32k * 512, or 16M. The >> maximum-size bounce buffer should not be the problem here; but for som= e >> reason, it looks like alignment is larger than max_transfer which shou= ld >> not normally be possible. I'm still playing with what should be the >> right patch, but hope to have something posted soon. >=20 > Are you still playing with it? Patch was posted here: https://lists.gnu.org/archive/html/qemu-devel/2016-11/msg01603.html --=20 Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org --DxJMTwEsOoSddENjNK6d0F3tA9WnnrBM0 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBCAAGBQJYKdxEAAoJEKeha0olJ0NqpIcIAKcNoG0VPi3D95PAYusiSJ5O eS5ware4iD9L/7W/zM2pZNDsv7cvRxV15VRjnRrcMy7I0HvZIOG3MvR74XD7k4w/ vOn4KxxJwaoSrIypRWvKu/1Fc86D/uy1zzT9aExtKcGhsuKH/NnGB/ifJ2lcO48P l6MKfMkyCAc/LrvprRJoImjhsoh7lN147weAPBngSz0yoeQUalkzMjpGa26hqWQs ihVZC/142Dltj2LJQBnFujVv9VmQJ9MErN53i6X00pw8ao3IE56H8erhkXQA3czZ BSS1bhOZ5BDlNG8ughOtOfY0LpM2XPe4R4v13gDnVXD5UwvNPl9OXoJxtSSoamA= =606L -----END PGP SIGNATURE----- --DxJMTwEsOoSddENjNK6d0F3tA9WnnrBM0--