Wait until mount unit is deactivated on unmount (#4733)

* Wait until mount unit is deactivated on unmount

The current code does not wait until the (bind) mount unit has been
actually deactivated (state "inactive"). This is especially problematic
when restoring a backup, where we deactivate all bind mounts before
restoring the target folder. Before the tarball is actually restored,
we delete all contents of the target folder. This lead to the situation
where the "rm -rf" command got executed before the bind mount actually
got unmounted.

The current code polls the state using an exponentially increasing
delay. Wait up to 30s for the bind mount to actually deactivate.

* Fix function name

* Fix missing await

* Address pytest errors

Change state of systemd unit according to use cases. Note that this
is currently rather fragile, and ideally we should have a smarter
mock service instead.

* Fix pylint

* Fix remaining

* Check transition fo failed as well

* Used alternative mocking mechanism

* Remove state lists in test_manager

---------

Co-authored-by: Mike Degatano <michael.degatano@gmail.com>

tests/api/test_mounts.py

@@ -142,7 +142,7 @@ async def test_api_create_dbus_error_mount_not_added(
         "/org/freedesktop/systemd1/unit/tmp_2dyellow_2emount",
     ]
     systemd_service.response_start_transient_unit = "/org/freedesktop/systemd1/job/7623"
-    systemd_unit_service.active_state = "failed"
+    systemd_unit_service.active_state = ["failed", "failed", "inactive"]
 
     resp = await api_client.post(
         "/mounts",
@@ -219,8 +219,16 @@ async def test_api_create_mount_fails_missing_mount_propagation(
     )
 
 
-async def test_api_update_mount(api_client: TestClient, coresys: CoreSys, mount):
+async def test_api_update_mount(
+    api_client: TestClient,
+    coresys: CoreSys,
+    all_dbus_services: dict[str, DBusServiceMock],
+    mount,
+):
     """Test updating a mount via API."""
+    systemd_service: SystemdService = all_dbus_services["systemd"]
+    systemd_unit_service: SystemdUnitService = all_dbus_services["systemd_unit"]
+    systemd_service.mock_systemd_unit = systemd_unit_service
     resp = await api_client.put(
         "/mounts/backup_test",
         json={
@@ -280,6 +288,7 @@ async def test_api_update_dbus_error_mount_remains(
     """Test mount remains in list with unsuccessful state if dbus error occurs during update."""
     systemd_service: SystemdService = all_dbus_services["systemd"]
     systemd_unit_service: SystemdUnitService = all_dbus_services["systemd_unit"]
+    systemd_unit_service.active_state = ["failed", "inactive"]
     systemd_service.response_get_unit = [
         "/org/freedesktop/systemd1/unit/tmp_2dyellow_2emount",
         DBusError("org.freedesktop.systemd1.NoSuchUnit", "error"),
@@ -321,7 +330,13 @@ async def test_api_update_dbus_error_mount_remains(
         "/org/freedesktop/systemd1/unit/tmp_2dyellow_2emount",
     ]
     systemd_service.response_start_transient_unit = "/org/freedesktop/systemd1/job/7623"
-    systemd_unit_service.active_state = "failed"
+    systemd_unit_service.active_state = [
+        "failed",
+        "inactive",
+        "inactive",
+        "failed",
+        "inactive",
+    ]
 
     resp = await api_client.put(
         "/mounts/backup_test",
@@ -385,8 +400,16 @@ async def test_api_reload_error_mount_missing(
     )
 
 
-async def test_api_delete_mount(api_client: TestClient, coresys: CoreSys, mount):
+async def test_api_delete_mount(
+    api_client: TestClient,
+    coresys: CoreSys,
+    all_dbus_services: dict[str, DBusServiceMock],
+    mount,
+):
     """Test deleting a mount via API."""
+    systemd_service: SystemdService = all_dbus_services["systemd"]
+    systemd_unit_service: SystemdUnitService = all_dbus_services["systemd_unit"]
+    systemd_service.mock_systemd_unit = systemd_unit_service
     resp = await api_client.delete("/mounts/backup_test")
     result = await resp.json()
     assert result["result"] == "ok"
@@ -455,9 +478,16 @@ async def test_api_create_backup_mount_sets_default(
 
 
 async def test_update_backup_mount_changes_default(
-    api_client: TestClient, coresys: CoreSys, mount
+    api_client: TestClient,
+    coresys: CoreSys,
+    all_dbus_services: dict[str, DBusServiceMock],
+    mount,
 ):
     """Test updating a backup mount may unset the default."""
+    systemd_unit_service: SystemdUnitService = all_dbus_services["systemd_unit"]
+    systemd_service: SystemdService = all_dbus_services["systemd"]
+    systemd_service.mock_systemd_unit = systemd_unit_service
+
     # Make another backup mount for testing
     resp = await api_client.post(
         "/mounts",
@@ -502,9 +532,16 @@ async def test_update_backup_mount_changes_default(
 
 
 async def test_delete_backup_mount_changes_default(
-    api_client: TestClient, coresys: CoreSys, mount
+    api_client: TestClient,
+    coresys: CoreSys,
+    all_dbus_services: dict[str, DBusServiceMock],
+    mount,
 ):
     """Test deleting a backup mount may unset the default."""
+    systemd_unit_service: SystemdUnitService = all_dbus_services["systemd_unit"]
+    systemd_service: SystemdService = all_dbus_services["systemd"]
+    systemd_service.mock_systemd_unit = systemd_unit_service
+
     # Make another backup mount for testing
     resp = await api_client.post(
         "/mounts",
@@ -535,11 +572,15 @@ async def test_delete_backup_mount_changes_default(
 async def test_backup_mounts_reload_backups(
     api_client: TestClient,
     coresys: CoreSys,
+    all_dbus_services: dict[str, DBusServiceMock],
     tmp_supervisor_data,
     path_extern,
     mount_propagation,
 ):
     """Test actions on a backup mount reload backups."""
+    systemd_unit_service: SystemdUnitService = all_dbus_services["systemd_unit"]
+    systemd_service: SystemdService = all_dbus_services["systemd"]
+    systemd_service.mock_systemd_unit = systemd_unit_service
     await coresys.mounts.load()
 
     with patch.object(BackupManager, "reload") as reload: