Merge pull request #1217 from vojtechtrefny/3.9-devel_btrfs-list-subv…

…olumes-fix

Misc fixes related to btrfs subvolume listing

blivet/devices/btrfs.py

@@ -40,6 +40,7 @@
 from ..formats import get_format, DeviceFormat
 from ..size import Size
 from ..mounts import mounts_cache
+from .. import missing_plugs
 
 import logging
 log = logging.getLogger("blivet")
@@ -374,12 +375,17 @@ def _list_subvolumes(self, mountpoint, snapshots_only=False):
         except (blockdev.BtrfsError, blockdev.BlockDevNotImplementedError) as e:
             log.debug("failed to list subvolumes: %s", e)
         else:
-            self._get_default_subvolume_id()
+            self._get_default_subvolume_id(mountpoint)
 
         return subvols
 
     def list_subvolumes(self, snapshots_only=False):
         subvols = []
+
+        if "btrfs" in missing_plugs:
+            log.debug("not listing btrfs subvolumes, libblockdev btrfs plugin is missing")
+            return subvols
+
         if flags.auto_dev_updates:
             self.setup(orig=True)
 
@@ -404,13 +410,16 @@ def list_subvolumes(self, snapshots_only=False):
     def remove_subvolume(self, name):
         raise NotImplementedError()
 
-    def _get_default_subvolume_id(self):
+    def _get_default_subvolume_id(self, mountpoint=None):
         subvolid = None
-        with self._do_temp_mount() as mountpoint:
-            try:
+
+        try:
+            if mountpoint:
                 subvolid = blockdev.btrfs.get_default_subvolume_id(mountpoint)
-            except (blockdev.BtrfsError, blockdev.BlockDevNotImplementedError) as e:
-                log.debug("failed to get default subvolume id: %s", e)
+            elif flags.auto_dev_updates:
+                subvolid = blockdev.btrfs.get_default_subvolume_id(mountpoint)
+        except (blockdev.BtrfsError, blockdev.BlockDevNotImplementedError) as e:
+            log.debug("failed to get default subvolume id: %s", e)
 
         self._default_subvolume_id = subvolid
 

tests/unit_tests/devices_test/btrfs_test.py

@@ -1,16 +1,17 @@
 import unittest
 
 try:
-    from unittest.mock import patch
+    from unittest.mock import patch, PropertyMock
 except ImportError:
-    from mock import patch
+    from mock import patch, PropertyMock
 
 import blivet
 
 from blivet.devices import StorageDevice
 from blivet.devices import BTRFSVolumeDevice
 from blivet.devices import BTRFSSubVolumeDevice
 from blivet.size import Size
+from blivet.formats.fs import BTRFS
 
 
 DEVICE_CLASSES = [
@@ -65,3 +66,28 @@ def test_device_id(self):
 
         sub = BTRFSSubVolumeDevice("testsub", parents=[vol])
         self.assertEqual(sub.device_id, "BTRFS-" + vol.uuid + "-testsub")
+
+    def test_btrfs_list_subvolumes(self):
+        bd = StorageDevice("bd1", fmt=blivet.formats.get_format("btrfs"),
+                           size=Size("2 GiB"), exists=True)
+
+        vol = BTRFSVolumeDevice("testvolume", parents=[bd])
+
+        with patch("blivet.devices.btrfs.blockdev.btrfs") as blockdev:
+            # not mounted and flags.auto_dev_updates is not set
+            vol.list_subvolumes()
+            blockdev.list_subvolumes.assert_not_called()
+            blockdev.get_default_subvolume_id.assert_not_called()
+
+            # mounted
+            with patch.object(BTRFS, "system_mountpoint", new=PropertyMock(return_value='/fake/mountpoint')):
+                vol.list_subvolumes()
+                blockdev.list_subvolumes.assert_called_with("/fake/mountpoint", snapshots_only=False)
+                blockdev.get_default_subvolume_id.assert_called_with("/fake/mountpoint")
+
+                # mounted but libblockdev btrfs plugin not available
+                blockdev.reset_mock()
+                with patch("blivet.devices.btrfs.missing_plugs", new={"btrfs"}):
+                    vol.list_subvolumes()
+                    blockdev.list_subvolumes.assert_not_called()
+                    blockdev.get_default_subvolume_id.assert_not_called()