From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49951) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZhiD6-00058b-E5 for qemu-devel@nongnu.org; Thu, 01 Oct 2015 14:04:08 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZhiD3-0005RQ-5m for qemu-devel@nongnu.org; Thu, 01 Oct 2015 14:04:04 -0400 Sender: Paolo Bonzini References: <1443717273-5280-1-git-send-email-jsnow@redhat.com> <1443717273-5280-2-git-send-email-jsnow@redhat.com> From: Paolo Bonzini Message-ID: <560D758E.7020309@redhat.com> Date: Thu, 1 Oct 2015 20:03:58 +0200 MIME-Version: 1.0 In-Reply-To: <1443717273-5280-2-git-send-email-jsnow@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [PATCH 1/3] block: prohibit migration during BlockJobs List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: John Snow , qemu-block@nongnu.org Cc: kwolf@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com On 01/10/2015 18:34, John Snow wrote: > Unless we can prove this to be safe for specific cases, > the default should be to prohibit migration during BlockJobs. Block jobs do not affect the current block, only other block device, hence they *are* safe for migration. What you want, I think, is the target not to be garbage when migration ends. Based on this you can block specific cases, namely mirror which you already do allow (patch 2) and backup except for sync='none'. Paolo > In conjunction with > "migration: disallow_migrate_add_blocker during migration", > this should be sufficient to disallow the blockjob from starting > in the event of an in-progress migration.