From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59199) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1an6V6-000437-7j for qemu-devel@nongnu.org; Mon, 04 Apr 2016 11:33:13 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1an6V1-0001iN-A9 for qemu-devel@nongnu.org; Mon, 04 Apr 2016 11:33:12 -0400 References: <1459783562-28859-1-git-send-email-kwolf@redhat.com> From: Eric Blake Message-ID: <57028919.6060006@redhat.com> Date: Mon, 4 Apr 2016 09:32:41 -0600 MIME-Version: 1.0 In-Reply-To: <1459783562-28859-1-git-send-email-kwolf@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="AsE5QcqxnvhqcifEblATlDdU2P7QouDA0" Subject: Re: [Qemu-devel] [PATCH for-2.6] block: Forbid I/O throttling on nodes with multiple parents for 2.6 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf , qemu-block@nongnu.org Cc: pbonzini@redhat.com, berto@igalia.com, qemu-devel@nongnu.org, stefanha@redhat.com This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --AsE5QcqxnvhqcifEblATlDdU2P7QouDA0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 04/04/2016 09:26 AM, Kevin Wolf wrote: > As the patches to move I/O throttling to BlockBackend didn't make it in= > time for the 2.6 release, but the release adds new ways of configuring > VMs whose behaviour would change once the move is done, we need to > outlaw such configurations temporarily. >=20 > The problem exists whenever a BDS has more users than just its BB, for > example it is used as a backing file for another node. (This wasn't > possible in 2.5 yet as we introduced node references to specify a > backing file only recently.) In these cases, the throttling would > apply to these other users now, but after moving throttling to the > BlockBackend the other users wouldn't be throttled any more. >=20 > This patch both prevents making new references to a throttled node as > well as using monitor commands to throttle a node with multiple parents= =2E >=20 > Compared to 2.5 this changes behaviour in some corner cases where > references were allowed before, like bs->file or Quorum children. It > seems reasonable to assume that users didn't use I/O throttling on such= > low level nodes. With the upcoming move of throttling into BlockBackend= , > such configurations won't be possible anyway. >=20 > Signed-off-by: Kevin Wolf > --- > block.c | 7 +++++++ > blockdev.c | 7 +++++++ > 2 files changed, 14 insertions(+) Reviewed-by: Eric Blake --=20 Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org --AsE5QcqxnvhqcifEblATlDdU2P7QouDA0 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/ iQEcBAEBCAAGBQJXAokZAAoJEKeha0olJ0NqRdEH/RKWRR+p++4LrFrsZd6JRqBy n20iBAt51h0VKPAgke7t+HXt6jmude8AENgiCGsDcxNCV932yKCFVqEBtUSc/7yW c0/rThKxoPYqHb7vpNTN+mjDEx4Ojo+jn0Cb4LtqHgrD2lqJxOG9Z6kNbDgnjXQ8 voJ4ShSh8ygrqtlkddD6BE/lqhlL11WfNj1gaUNVtBOQHCvfh+0MLxtPuWo64Sul tSW5sbOgD8VUqdgu2RIwfyzFhIkki2CJclOHpdvlNa+y2KEIRD8jBKLAW0oWVcmX m6UwiitH2eGklSchVHBDmSl3mLljbpE8XssodmQErsUf8a0VVLxQQvLjYJ2cjs0= =iIMj -----END PGP SIGNATURE----- --AsE5QcqxnvhqcifEblATlDdU2P7QouDA0--