libsnapshot: Cancel/merge existing update before begin
Attempt to cancel or merge an existing update before starting
a new one.
Test: libsnapshot_test
Change-Id: Ic534db846f1fe97bd7ca1f176a9494fbc6a0f8d5
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h b/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
index 8d29e40..6130a10 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
@@ -127,8 +127,9 @@
// will fail if GetUpdateState() != None.
bool BeginUpdate();
- // Cancel an update; any snapshots will be deleted. This will fail if the
- // state != Initiated or None.
+ // Cancel an update; any snapshots will be deleted. This is allowed if the
+ // state == Initiated, None, or Unverified (before rebooting to the new
+ // slot).
bool CancelUpdate();
// Mark snapshot writes as having completed. After this, new snapshots cannot
@@ -395,6 +396,13 @@
// The reverse of MapPartitionWithSnapshot.
bool UnmapPartitionWithSnapshot(LockedFile* lock, const std::string& target_partition_name);
+ // If there isn't a previous update, return true. |needs_merge| is set to false.
+ // If there is a previous update but the device has not boot into it, tries to cancel the
+ // update and delete any snapshots. Return true if successful. |needs_merge| is set to false.
+ // If there is a previous update and the device has boot into it, do nothing and return true.
+ // |needs_merge| is set to true.
+ bool TryCancelUpdate(bool* needs_merge);
+
std::string gsid_dir_;
std::string metadata_dir_;
std::unique_ptr<IDeviceInfo> device_;
diff --git a/fs_mgr/libsnapshot/snapshot.cpp b/fs_mgr/libsnapshot/snapshot.cpp
index 0bf0365..803bdb5 100644
--- a/fs_mgr/libsnapshot/snapshot.cpp
+++ b/fs_mgr/libsnapshot/snapshot.cpp
@@ -131,6 +131,16 @@
}
bool SnapshotManager::BeginUpdate() {
+ bool needs_merge = false;
+ if (!TryCancelUpdate(&needs_merge)) {
+ return false;
+ }
+ if (needs_merge) {
+ LOG(INFO) << "Wait for merge (if any) before beginning a new update.";
+ auto state = ProcessUpdateState();
+ LOG(INFO) << "Merged with state = " << state;
+ }
+
auto file = LockExclusive();
if (!file) return false;
@@ -143,6 +153,19 @@
}
bool SnapshotManager::CancelUpdate() {
+ bool needs_merge = false;
+ if (!TryCancelUpdate(&needs_merge)) {
+ return false;
+ }
+ if (needs_merge) {
+ LOG(ERROR) << "Cannot cancel update after it has completed or started merging";
+ }
+ return !needs_merge;
+}
+
+bool SnapshotManager::TryCancelUpdate(bool* needs_merge) {
+ *needs_merge = false;
+
auto file = LockExclusive();
if (!file) return false;
@@ -167,8 +190,8 @@
return RemoveAllUpdateState(file.get());
}
}
- LOG(ERROR) << "Cannot cancel update after it has completed or started merging";
- return false;
+ *needs_merge = true;
+ return true;
}
bool SnapshotManager::RemoveAllUpdateState(LockedFile* lock) {
diff --git a/fs_mgr/libsnapshot/snapshot_test.cpp b/fs_mgr/libsnapshot/snapshot_test.cpp
index 36982a9..bc764fd 100644
--- a/fs_mgr/libsnapshot/snapshot_test.cpp
+++ b/fs_mgr/libsnapshot/snapshot_test.cpp
@@ -761,8 +761,7 @@
// Also test UnmapUpdateSnapshot unmaps everything.
// Also test first stage mount and merge after this.
TEST_F(SnapshotUpdateTest, FullUpdateFlow) {
- // OTA client calls CancelUpdate then BeginUpdate before doing anything.
- ASSERT_TRUE(sm->CancelUpdate());
+ // OTA client calls BeginUpdate before doing anything.
ASSERT_TRUE(sm->BeginUpdate());
// OTA client blindly unmaps all partitions that are possibly mapped.