From patchwork Mon Jul 29 15:36:12 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 262828 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 5C46F2C00F3 for ; Tue, 30 Jul 2013 01:38:28 +1000 (EST) Received: from localhost ([::1]:47269 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V3pWk-0000cZ-6J for incoming@patchwork.ozlabs.org; Mon, 29 Jul 2013 11:38:26 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51561) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V3pUy-0006OK-4N for qemu-devel@nongnu.org; Mon, 29 Jul 2013 11:36:41 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1V3pUs-0002dZ-FN for qemu-devel@nongnu.org; Mon, 29 Jul 2013 11:36:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36413) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V3pUs-0002dM-7k; Mon, 29 Jul 2013 11:36:30 -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 r6TFaTE1024354 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Mon, 29 Jul 2013 11:36:29 -0400 Received: from localhost (ovpn-112-50.ams2.redhat.com [10.36.112.50]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id r6TFaSos021543; Mon, 29 Jul 2013 11:36:29 -0400 From: Stefan Hajnoczi To: Date: Mon, 29 Jul 2013 17:36:12 +0200 Message-Id: <1375112172-24863-7-git-send-email-stefanha@redhat.com> In-Reply-To: <1375112172-24863-1-git-send-email-stefanha@redhat.com> References: <1375112172-24863-1-git-send-email-stefanha@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.11 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: Anthony Liguori , qemu-stable@nongnu.org, Stefan Hajnoczi Subject: [Qemu-devel] [PATCH 6/6] dataplane: refuse to start if device is already in use X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Dataplane must check whether a block device is in use before launching the dataplane thread. This is necessary since the thread does not synchronize with the main loop and I/O requests could cause corruption. One example is when a drive is added and a block job is started before hotplugging the virtio-blk-pci adapter. In this case we must not use dataplane mode. Cc: qemu-stable@nongnu.org Reviewed-by: Kevin Wolf Signed-off-by: Stefan Hajnoczi --- hw/block/dataplane/virtio-blk.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c index 63c3ffa..411becc 100644 --- a/hw/block/dataplane/virtio-blk.c +++ b/hw/block/dataplane/virtio-blk.c @@ -415,6 +415,14 @@ bool virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *blk, return false; } + /* If dataplane is (re-)enabled while the guest is running there could be + * block jobs that can conflict. + */ + if (bdrv_in_use(blk->conf.bs)) { + error_report("cannot start dataplane thread while device is in use"); + return false; + } + fd = raw_get_aio_fd(blk->conf.bs); if (fd < 0) { error_report("drive is incompatible with x-data-plane, "