iotests.py: Allow concurrent qemu instances

By adding an optional suffix to the files used for communication with a
VM, we can launch multiple VM instances concurrently.

Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

tests/qemu-iotests/iotests.py

@@ -140,8 +140,10 @@ def log(msg, filters=[]):
 class VM(qtest.QEMUQtestMachine):
     '''A QEMU VM'''
 
-    def __init__(self):
-        super(VM, self).__init__(qemu_prog, qemu_opts, test_dir=test_dir,
+    def __init__(self, path_suffix=''):
+        name = "qemu%s-%d" % (path_suffix, os.getpid())
+        super(VM, self).__init__(qemu_prog, qemu_opts, name=name,
+                                 test_dir=test_dir,
                                  socket_scm_helper=socket_scm_helper)
         if debug:
             self._debug = True