utils_libvirt/libvirt_disk: add function to get disk by serial

Use the SERIAL that can be set via libvirt, to select
its disk path under /dev/.

Suggested-by: Chunfu Wen <[email protected]>
Signed-off-by: Sebastian Mitterle <[email protected]>

virttest/utils_libvirt/libvirt_disk.py

@@ -102,6 +102,31 @@ def get_non_root_disk_name(session):
         return name.strip(), mpoint.strip()
 
 
+def get_disk_by_serial(session, serial):
+    """
+    Gets the disk by its serial value
+
+    :param session: VM session
+    :param serial: The expected serial value
+    :return path: absolute path of disk
+                  e.g. /dev/sda
+    :raises TestError: If the disk cannot be found.
+    """
+    cmd = "lsblk -n -p -l -o NAME,SERIAL"
+    s, o = utils_misc.cmd_status_output(cmd,
+                                        ignore_status=False,
+                                        shell=True,
+                                        verbose=True,
+                                        session=session)
+    if s:
+        raise exceptions.TestError("Couldn't list block devices: '%s'" % o)
+    for line in o.split("\n"):
+        match = re.match(r'(/dev/[a-z]+)[\s\t]+%s' % serial, line)
+        if match:
+            return match.groups()[0]
+    raise exceptions.TestError("Couldn't find disk with serial in:\n%s" % o)
+
+
 def create_disk(disk_type, path=None, size="500M", disk_format="raw", extra='',
                 session=None):
     """