Commit b0f2027c authored by Stefan Hajnoczi's avatar Stefan Hajnoczi
Browse files

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: default avatarKevin Wolf <kwolf@redhat.com>
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent 84db52d0

hw/block/dataplane/virtio-blk.c

+8 −0
Original line number Diff line number Diff line
@@ -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, "