From: Stefan Hajnoczi <stefa...@redhat.com>
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-sta...@nongnu.org
Reviewed-by: Kevin Wolf <kw...@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
(cherry picked from commit b0f2027cde31c645524256763672e09eeb204a9a)
Signed-off-by: Michael Roth <mdr...@linux.vnet.ibm.com>
---
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 0356665..a58cc53 100644
--- a/hw/block/dataplane/virtio-blk.c
+++ b/hw/block/dataplane/virtio-blk.c
@@ -418,6 +418,14 @@ 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, "
--
1.7.9.5
