From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51310) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V25k1-0007Ir-Pq for qemu-devel@nongnu.org; Wed, 24 Jul 2013 16:32:58 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1V25k0-0006j7-Nx for qemu-devel@nongnu.org; Wed, 24 Jul 2013 16:32:57 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56827) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V25k0-0006io-Gx for qemu-devel@nongnu.org; Wed, 24 Jul 2013 16:32:56 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r6OKWtpO027778 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Wed, 24 Jul 2013 16:32:55 -0400 Message-ID: <51F039F5.90109@redhat.com> Date: Wed, 24 Jul 2013 14:32:53 -0600 From: Eric Blake MIME-Version: 1.0 References: <1374530960-22031-1-git-send-email-imain@redhat.com> <1374530960-22031-2-git-send-email-imain@redhat.com> <20130724105543.GA3623@dhcp-200-207.str.redhat.com> In-Reply-To: <20130724105543.GA3623@dhcp-200-207.str.redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="cxeexl4bi0xhsTmUq4dmgCoLMx55gsf3v" Subject: Re: [Qemu-devel] [PATCH V6 1/3] Implement sync modes for drive-backup. List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: famz@redhat.com, qemu-devel@nongnu.org, rjones@redhat.com, Ian Main , stefanha@redhat.com, pbonzini@redhat.com This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --cxeexl4bi0xhsTmUq4dmgCoLMx55gsf3v Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 07/24/2013 04:55 AM, Kevin Wolf wrote: > Unconditionally overriding format for NEW_IMAGE_MODE_EXISTING is > definitely wrong. It's the user's choice which COW format to use for th= e > backup image. There's no reason why it has to be the same format as the= > image that is being backed up. >=20 > Before, bs->drv->format_name was a default for the case where a new > image had to be created and no format was given; and the format of > existing images could be probed. This is still what makes most sense to= > me. What's even the goal with this change? Furthermore, I'm proposing that for 1.6, we should make the format argument mandatory for drive-backup. We made it optional for drive-mirror, to allow for probing, but there have been CVEs in the past due to probing of a raw file gone wrong. We can always relax a mandatory argument into an optional one in 1.7, if we decide that probing can be done safely, but we can never turn an optional argument into a mandatory one once the initial release bakes in the option. It would make the code a lot simpler to just have a mandatory format argument, instead of having to bake in and document hueristics on which format is picked when the caller doesn't provide one. --=20 Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org --cxeexl4bi0xhsTmUq4dmgCoLMx55gsf3v 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/ iQEcBAEBCAAGBQJR8Dn1AAoJEKeha0olJ0Nq7aYH/ii3DAfAPUcTbIQVIgHbC7zf 56FCudER9F3kL2f61yRnvdr7hsT1i2yUEQQc1Dg/2PjhQU9HDXZW1KmZ0XAM79py rEhlWuaSmk/XwOmGKNPWRzI2uIxTeRSMjvJpgHsP8Fx0nmfhhcAxa08QmvhHGOEA g4dPl8LQXCDNkKYVSUgruXiVlkHQa8Y8t0T5LL9WNnR8p7K4eQrydzkY0DeEx27z 3toS997CJwGmOlN7tGkv/nG+T3h2OZtXsaZVKVcA80LcuJM+tYwPP7xSIix8Qx7U ir0bOuiJFBKhm+2ANb1nut3hEFdPhrtpig9d0BTzw+o/zXk/PUdXWBeMU3o8I7g= =WYrF -----END PGP SIGNATURE----- --cxeexl4bi0xhsTmUq4dmgCoLMx55gsf3v--