From 43d9f1833fd79d9fef8b7847f9aeb27b4d51fa6f Mon Sep 17 00:00:00 2001
From: David Anderson <dvander@google.com>
Date: Tue, 10 Dec 2019 21:18:28 -0800
Subject: [PATCH] remount: Refactor fs_mgr_overlayfs_teardown

This pulls code for mapping the scratch device into a separate function.
It also avoids implicitly failing by passing an empty device string.
Finally, it calls GetScratchDevice, to remove a caller of the deprecated
method fs_mgr_overlayfs_scratch_device().

Bug: 134949511
Test: adb remount and adb_remount_test.sh
Change-Id: If4a543d3fa26af3f8578ec8b236859c8e4d9bfd8
---
 fs_mgr/fs_mgr_overlayfs.cpp | 38 ++++++++++++++++++++++++-------------
 1 file changed, 25 insertions(+), 13 deletions(-)

diff --git a/fs_mgr/fs_mgr_overlayfs.cpp b/fs_mgr/fs_mgr_overlayfs.cpp
index a2fe22e5c..e236d79e1 100644
--- a/fs_mgr/fs_mgr_overlayfs.cpp
+++ b/fs_mgr/fs_mgr_overlayfs.cpp
@@ -1252,6 +1252,27 @@ bool fs_mgr_overlayfs_setup(const char* backing, const char* mount_point, bool*
     return ret;
 }
 
+static bool GetAndMapScratchDeviceIfNeeded(std::string* device) {
+    *device = GetScratchDevice();
+    if (!device->empty()) {
+        return true;
+    }
+
+    auto strategy = GetScratchStrategy();
+    if (strategy == ScratchStrategy::kDynamicPartition) {
+        auto metadata_slot = fs_mgr_overlayfs_slot_number();
+        CreateLogicalPartitionParams params = {
+                .block_device = fs_mgr_overlayfs_super_device(metadata_slot),
+                .metadata_slot = metadata_slot,
+                .partition_name = android::base::Basename(kScratchMountPoint),
+                .force_writable = true,
+                .timeout_ms = 10s,
+        };
+        return CreateLogicalPartition(params, device);
+    }
+    return false;
+}
+
 // Returns false if teardown not permitted, errno set to last error.
 // If something is altered, set *change.
 bool fs_mgr_overlayfs_teardown(const char* mount_point, bool* change) {
@@ -1261,20 +1282,11 @@ bool fs_mgr_overlayfs_teardown(const char* mount_point, bool* change) {
     // specific override entries.
     auto mount_scratch = false;
     if ((mount_point != nullptr) && !fs_mgr_overlayfs_already_mounted(kScratchMountPoint, false)) {
-        auto scratch_device = fs_mgr_overlayfs_scratch_device();
-        if (scratch_device.empty()) {
-            auto metadata_slot = fs_mgr_overlayfs_slot_number();
-            CreateLogicalPartitionParams params = {
-                    .block_device = fs_mgr_overlayfs_super_device(metadata_slot),
-                    .metadata_slot = metadata_slot,
-                    .partition_name = android::base::Basename(kScratchMountPoint),
-                    .force_writable = true,
-                    .timeout_ms = 10s,
-            };
-            CreateLogicalPartition(params, &scratch_device);
+        std::string scratch_device;
+        if (GetAndMapScratchDeviceIfNeeded(&scratch_device)) {
+            mount_scratch = fs_mgr_overlayfs_mount_scratch(scratch_device,
+                                                           fs_mgr_overlayfs_scratch_mount_type());
         }
-        mount_scratch = fs_mgr_overlayfs_mount_scratch(scratch_device,
-                                                       fs_mgr_overlayfs_scratch_mount_type());
     }
     for (const auto& overlay_mount_point : kOverlayMountPoints) {
         ret &= fs_mgr_overlayfs_teardown_one(