From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39649) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V3n5o-0005fS-OH for qemu-devel@nongnu.org; Mon, 29 Jul 2013 09:02:33 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1V3n5j-00013q-NW for qemu-devel@nongnu.org; Mon, 29 Jul 2013 09:02:28 -0400 From: Stefan Hajnoczi Date: Mon, 29 Jul 2013 15:02:00 +0200 Message-Id: <1375102920-18817-5-git-send-email-stefanha@redhat.com> In-Reply-To: <1375102920-18817-1-git-send-email-stefanha@redhat.com> References: <1375102920-18817-1-git-send-email-stefanha@redhat.com> Subject: [Qemu-devel] [PATCH v3 4/4] dataplane: refuse to start if device is already in use List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Kevin Wolf , qemu-stable@nongnu.org, Stefan Hajnoczi , Juan Quintela 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 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, " -- 1.8.1.4