From b0f2027cde31c645524256763672e09eeb204a9a Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Mon, 29 Jul 2013 15:02:00 +0200 Subject: [PATCH] dataplane: refuse to start if device is already in use 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, " -- 2.7.4