lvm zap: refuse to zap mapper devices

Fixes: http://tracker.ceph.com/issues/24504

Signed-off-by: Andrew Schoen <aschoen@redhat.com>
(cherry picked from commit 8e602d5)

src/ceph-volume/ceph_volume/devices/lvm/zap.py

@@ -49,6 +49,9 @@ def __init__(self, argv):
     @decorators.needs_root
     def zap(self, args):
         device = args.device
+        if disk.is_mapper_device(device):
+            terminal.error("Refusing to zap the mapper device: {}".format(device))
+            raise SystemExit(1)
         lv = api.get_lv_from_argument(device)
         if lv:
             # we are zapping a logical volume

src/ceph-volume/ceph_volume/tests/devices/test_zap.py

@@ -14,4 +14,13 @@ def test_main_shows_full_help(self, capsys):
             lvm.zap.Zap(argv=['--help']).main()
         stdout, stderr = capsys.readouterr()
         assert 'optional arguments' in stdout
-        assert 'positional arguments' in stdout
+
+    @pytest.mark.parametrize('device_name', [
+        '/dev/mapper/foo',
+        '/dev/dm-0',
+    ])
+    def test_can_not_zap_mapper_device(self, capsys, is_root, device_name):
+        with pytest.raises(SystemExit):
+            lvm.zap.Zap(argv=[device_name]).main()
+        stdout, stderr = capsys.readouterr()
+        assert 'Refusing to zap' in stdout