remount: Use /data for backing scratch storage.

Currently, this is only enabled for Virtual A/B devices. When /data uses
F2FS, then proper pinning support must be enabled.

Because /data cannot be mounted in recovery, we can't delete the scratch
image backed by /data while in fastbootd. Instead, we mark it as
disabled in /metadata. The remount command now has an init script that
checks for and removes a disabled scratch partition.

Bug: 134949511
Test: adb remount on V A/B device with patched F2FS
Change-Id: Ifc8720378259654472d3822e97059b6c366f601d

1 files changed, 22 insertions, 0 deletions

diff --git a/fs_mgr/clean_scratch_files.cpp b/fs_mgr/clean_scratch_files.cpp
new file mode 100644
index 000000000..42fe35a59
--- /dev/null
+++ b/fs_mgr/clean_scratch_files.cpp
@@ -0,0 +1,22 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <fs_mgr_overlayfs.h>
+
+int main() {
+    android::fs_mgr::CleanupOldScratchFiles();
+    return 0;
+}