From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36186) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UjwyV-0003Ja-Mf for qemu-devel@nongnu.org; Tue, 04 Jun 2013 15:33:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UjwyQ-0004LL-QS for qemu-devel@nongnu.org; Tue, 04 Jun 2013 15:32:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:7825) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UjwyQ-0004LE-IP for qemu-devel@nongnu.org; Tue, 04 Jun 2013 15:32:50 -0400 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r54JWnOp020213 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Tue, 4 Jun 2013 15:32:49 -0400 Message-ID: <51AE40E0.2010401@redhat.com> Date: Tue, 04 Jun 2013 13:32:48 -0600 From: Eric Blake MIME-Version: 1.0 References: <1370271492-5259-1-git-send-email-stefanha@redhat.com> <87ppw1rfw8.fsf@blackfin.pond.sub.org> <51AE1E3B.9030006@redhat.com> <87fvwxllwo.fsf@blackfin.pond.sub.org> In-Reply-To: <87fvwxllwo.fsf@blackfin.pond.sub.org> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="----enig2KBPKWJNPFMKWXFVVLCKK" Subject: Re: [Qemu-devel] [PATCH] blockdev: reset werror/rerror on drive_del List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Markus Armbruster Cc: Kevin Wolf , Paolo Bonzini , qemu-devel@nongnu.org, Stefan Hajnoczi , dron@redhat.com This is an OpenPGP/MIME signed message (RFC 4880 and 3156) ------enig2KBPKWJNPFMKWXFVVLCKK Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 06/04/2013 01:24 PM, Markus Armbruster wrote: > Paolo Bonzini writes: >=20 >> Il 04/06/2013 18:37, Markus Armbruster ha scritto: >>> I figure the bit that can't be resolved now is letting the user switc= h >>> off "stop on error" safely before a drive_del. Even if we had a comm= and >>> for that, there'd still be a window between that command's execution = and >>> drive_del's. Your patch solves the problem by having drive_del switc= h >>> it off unconditionally. Oookay, but please document it, because it's= >>> not exactly obvious. >> >> It is not obvious, but it is not surprising either when you see it (i.= e. >> you won't really be surprised by the errors in the guest and won't nee= d >> to know that, under the hood, rerror has been changed from the value y= ou >> specified). >> > This is drive_add's documentation in hmp-commands.hx: >=20 > Remove host block device. The result is that guest generated IO is= > no longer submitted against the host device underlying the disk. > Once a drive has been deleted, the QEMU Block layer returns -EIO > which results in IO errors in the guest for applications that are > reading/writing to the device. >=20 > Suggest to add: >=20 > These errors are always reported to the guest, regardless of the > drive's error actions (drive options rerror, werror). >=20 > Independently, libvirt needs fixing. Total agreement that libvirt needs to use a saner disk hot-unplug sequence when it is known that qemu provides one. I've filed https://bugzilla.redhat.com/show_bug.cgi?id=3D970761 to remind us to fix libvirt. --=20 Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org ------enig2KBPKWJNPFMKWXFVVLCKK Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.13 (GNU/Linux) Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBCAAGBQJRrkDgAAoJEKeha0olJ0Nqr/YH/ReMvyWSlC2MqKG2ntY8iz83 xQ3Kj7apGp1BniCbvPUEAJ5pEV6oM4huIi0/EAV6zgBGHcmbGGkYYhm4rrhctQAM fr0RC7QAvLcRi2D44a3fQuXqVYWACun65LK1AXKfIEC/mUFbo8HPK67n2x0kt4+J CFw1gDXtShZks7iS4t3MPhOETLzFscgpagA+KULvyQxPZJc5BQAlAfiOqT6tRlsR NIXuiwnPTjLqxA2PAKO7nQhNd1k7JTQKgKsEomAdRA0Igtn9GnheNFTaWb9V0L9k Yz9bPF5BYrLjoTlk5K9OjEnxY70OoKG/J/B948puW8GXX+twpjlradMEDLqCRXo= =NYd2 -----END PGP SIGNATURE----- ------enig2KBPKWJNPFMKWXFVVLCKK--