Merge "Crash during OTA merge may lead to blocks with stale data" (39b47504) · Commits · e / os / android_system_core

fs_mgr/libsnapshot/snapuserd/cow_snapuserd_test.cpp

+203 −19

Original line number	Diff line number	Diff line
		@@ -96,6 +96,8 @@ class TempDevice {
		class CowSnapuserdTest final {
		public:
		bool Setup();
		bool SetupOrderedOps();
		bool SetupOrderedOpsInverted();
		bool SetupCopyOverlap_1();
		bool SetupCopyOverlap_2();
		bool Merge();
		@@ -103,6 +105,8 @@ class CowSnapuserdTest final {
		void ReadSnapshotDeviceAndValidate();
		void Shutdown();
		void MergeInterrupt();
		void MergeInterruptFixed(int duration);
		void MergeInterruptRandomly(int max_duration);
		void ReadDmUserBlockWithoutDaemon();

		std::string snapshot_dev() const { return snapshot_dev_->path(); }
		@@ -117,6 +121,8 @@ class CowSnapuserdTest final {
		void StartMerge();

		void CreateCowDevice();
		void CreateCowDeviceOrderedOps();
		void CreateCowDeviceOrderedOpsInverted();
		void CreateCowDeviceWithCopyOverlap_1();
		void CreateCowDeviceWithCopyOverlap_2();
		bool SetupDaemon();
		@@ -197,6 +203,18 @@ bool CowSnapuserdTest::Setup() {
		return setup_ok_;
		}

		bool CowSnapuserdTest::SetupOrderedOps() {
		CreateBaseDevice();
		CreateCowDeviceOrderedOps();
		return SetupDaemon();
		}

		bool CowSnapuserdTest::SetupOrderedOpsInverted() {
		CreateBaseDevice();
		CreateCowDeviceOrderedOpsInverted();
		return SetupDaemon();
		}

		bool CowSnapuserdTest::SetupCopyOverlap_1() {
		CreateBaseDevice();
		CreateCowDeviceWithCopyOverlap_1();
		@@ -383,6 +401,112 @@ void CowSnapuserdTest::CreateCowDeviceWithCopyOverlap_1() {
		true);
		}

		void CowSnapuserdTest::CreateCowDeviceOrderedOpsInverted() {
		unique_fd rnd_fd;
		loff_t offset = 0;

		std::string path = android::base::GetExecutableDirectory();
		cow_system_ = std::make_unique<TemporaryFile>(path);

		rnd_fd.reset(open("/dev/random", O_RDONLY));
		ASSERT_TRUE(rnd_fd > 0);

		std::unique_ptr<uint8_t[]> random_buffer_1_ = std::make_unique<uint8_t[]>(size_);

		// Fill random data
		for (size_t j = 0; j < (size_ / 1_MiB); j++) {
		ASSERT_EQ(ReadFullyAtOffset(rnd_fd, (char*)random_buffer_1_.get() + offset, 1_MiB, 0),
		true);

		offset += 1_MiB;
		}

		CowOptions options;
		options.compression = "gz";
		CowWriter writer(options);

		ASSERT_TRUE(writer.Initialize(cow_system_->fd));

		size_t num_blocks = size_ / options.block_size;
		size_t blk_end_copy = num_blocks * 2;
		size_t source_blk = num_blocks - 1;
		size_t blk_src_copy = blk_end_copy - 1;

		size_t x = num_blocks;
		while (1) {
		ASSERT_TRUE(writer.AddCopy(source_blk, blk_src_copy));
		x -= 1;
		if (x == 0) {
		break;
		}
		source_blk -= 1;
		blk_src_copy -= 1;
		}

		// Flush operations
		ASSERT_TRUE(writer.Finalize());
		// Construct the buffer required for validation
		orig_buffer_ = std::make_unique<uint8_t[]>(total_base_size_);
		// Read the entire base device
		ASSERT_EQ(android::base::ReadFullyAtOffset(base_fd_, orig_buffer_.get(), total_base_size_, 0),
		true);
		// Merged Buffer
		memmove(orig_buffer_.get(), (char*)orig_buffer_.get() + size_, size_);
		}

		void CowSnapuserdTest::CreateCowDeviceOrderedOps() {
		unique_fd rnd_fd;
		loff_t offset = 0;

		std::string path = android::base::GetExecutableDirectory();
		cow_system_ = std::make_unique<TemporaryFile>(path);

		rnd_fd.reset(open("/dev/random", O_RDONLY));
		ASSERT_TRUE(rnd_fd > 0);

		std::unique_ptr<uint8_t[]> random_buffer_1_ = std::make_unique<uint8_t[]>(size_);

		// Fill random data
		for (size_t j = 0; j < (size_ / 1_MiB); j++) {
		ASSERT_EQ(ReadFullyAtOffset(rnd_fd, (char*)random_buffer_1_.get() + offset, 1_MiB, 0),
		true);

		offset += 1_MiB;
		}

		CowOptions options;
		options.compression = "gz";
		CowWriter writer(options);

		ASSERT_TRUE(writer.Initialize(cow_system_->fd));

		size_t num_blocks = size_ / options.block_size;
		size_t x = num_blocks;
		size_t source_blk = 0;
		size_t blk_src_copy = num_blocks;

		while (1) {
		ASSERT_TRUE(writer.AddCopy(source_blk, blk_src_copy));

		x -= 1;
		if (x == 0) {
		break;
		}
		source_blk += 1;
		blk_src_copy += 1;
		}

		// Flush operations
		ASSERT_TRUE(writer.Finalize());
		// Construct the buffer required for validation
		orig_buffer_ = std::make_unique<uint8_t[]>(total_base_size_);
		// Read the entire base device
		ASSERT_EQ(android::base::ReadFullyAtOffset(base_fd_, orig_buffer_.get(), total_base_size_, 0),
		true);
		// Merged Buffer
		memmove(orig_buffer_.get(), (char*)orig_buffer_.get() + size_, size_);
		}

		void CowSnapuserdTest::CreateCowDevice() {
		unique_fd rnd_fd;
		loff_t offset = 0;
		@@ -597,6 +721,7 @@ void CowSnapuserdTest::ValidateMerge() {

		void CowSnapuserdTest::SimulateDaemonRestart() {
		Shutdown();
		std::this_thread::sleep_for(500ms);
		SetDeviceControlName();
		StartSnapuserdDaemon();
		InitCowDevice();
		@@ -605,6 +730,34 @@ void CowSnapuserdTest::SimulateDaemonRestart() {
		CreateSnapshotDevice();
		}

		void CowSnapuserdTest::MergeInterruptRandomly(int max_duration) {
		std::srand(std::time(nullptr));
		StartMerge();

		for (int i = 0; i < 20; i++) {
		int duration = std::rand() % max_duration;
		std::this_thread::sleep_for(std::chrono::milliseconds(duration));
		SimulateDaemonRestart();
		StartMerge();
		}

		SimulateDaemonRestart();
		ASSERT_TRUE(Merge());
		}

		void CowSnapuserdTest::MergeInterruptFixed(int duration) {
		StartMerge();

		for (int i = 0; i < 25; i++) {
		std::this_thread::sleep_for(std::chrono::milliseconds(duration));
		SimulateDaemonRestart();
		StartMerge();
		}

		SimulateDaemonRestart();
		ASSERT_TRUE(Merge());
		}

		void CowSnapuserdTest::MergeInterrupt() {
		// Interrupt merge at various intervals
		StartMerge();
		@@ -669,10 +822,9 @@ void CowSnapuserdMetadataTest::ValidatePartialFilledArea() {
		void* buffer = snapuserd_->GetExceptionBuffer(1);
		loff_t offset = 0;
		struct disk_exception* de;
		for (int i = 0; i < 12; i++) {
		for (int i = 11; i >= 0; i--) {
		de = reinterpret_cast<struct disk_exception>((char)buffer + offset);
		ASSERT_EQ(de->old_chunk, i);
		ASSERT_EQ(de->new_chunk, new_chunk);
		offset += sizeof(struct disk_exception);
		new_chunk += 1;
		}
		@@ -811,71 +963,71 @@ void CowSnapuserdMetadataTest::ValidateMetadata() {

		de = reinterpret_cast<struct disk_exception>((char)buffer + offset);
		ASSERT_EQ(de->old_chunk, 100);
		ASSERT_EQ(de->new_chunk, 522);
		ASSERT_EQ(de->new_chunk, 521);
		offset += sizeof(struct disk_exception);

		de = reinterpret_cast<struct disk_exception>((char)buffer + offset);
		ASSERT_EQ(de->old_chunk, 105);
		ASSERT_EQ(de->new_chunk, 524);
		ASSERT_EQ(de->new_chunk, 522);
		offset += sizeof(struct disk_exception);

		de = reinterpret_cast<struct disk_exception>((char)buffer + offset);
		ASSERT_EQ(de->old_chunk, 110);
		ASSERT_EQ(de->new_chunk, 526);
		ASSERT_EQ(de->new_chunk, 523);
		offset += sizeof(struct disk_exception);

		// The next 4 operations are batch merged as
		// both old and new chunk are contiguous
		de = reinterpret_cast<struct disk_exception>((char)buffer + offset);
		ASSERT_EQ(de->old_chunk, 50);
		ASSERT_EQ(de->new_chunk, 528);
		ASSERT_EQ(de->old_chunk, 53);
		ASSERT_EQ(de->new_chunk, 524);
		offset += sizeof(struct disk_exception);

		de = reinterpret_cast<struct disk_exception>((char)buffer + offset);
		ASSERT_EQ(de->old_chunk, 51);
		ASSERT_EQ(de->new_chunk, 529);
		ASSERT_EQ(de->old_chunk, 52);
		ASSERT_EQ(de->new_chunk, 525);
		offset += sizeof(struct disk_exception);

		de = reinterpret_cast<struct disk_exception>((char)buffer + offset);
		ASSERT_EQ(de->old_chunk, 52);
		ASSERT_EQ(de->new_chunk, 530);
		ASSERT_EQ(de->old_chunk, 51);
		ASSERT_EQ(de->new_chunk, 526);
		offset += sizeof(struct disk_exception);

		de = reinterpret_cast<struct disk_exception>((char)buffer + offset);
		ASSERT_EQ(de->old_chunk, 53);
		ASSERT_EQ(de->new_chunk, 531);
		ASSERT_EQ(de->old_chunk, 50);
		ASSERT_EQ(de->new_chunk, 527);
		offset += sizeof(struct disk_exception);

		// This is handling overlap operation with
		// two batch merge operations.
		de = reinterpret_cast<struct disk_exception>((char)buffer + offset);
		ASSERT_EQ(de->old_chunk, 18);
		ASSERT_EQ(de->new_chunk, 533);
		ASSERT_EQ(de->new_chunk, 528);
		offset += sizeof(struct disk_exception);

		de = reinterpret_cast<struct disk_exception>((char)buffer + offset);
		ASSERT_EQ(de->old_chunk, 19);
		ASSERT_EQ(de->new_chunk, 534);
		ASSERT_EQ(de->new_chunk, 529);
		offset += sizeof(struct disk_exception);

		de = reinterpret_cast<struct disk_exception>((char)buffer + offset);
		ASSERT_EQ(de->old_chunk, 20);
		ASSERT_EQ(de->new_chunk, 535);
		ASSERT_EQ(de->new_chunk, 530);
		offset += sizeof(struct disk_exception);

		de = reinterpret_cast<struct disk_exception>((char)buffer + offset);
		ASSERT_EQ(de->old_chunk, 21);
		ASSERT_EQ(de->new_chunk, 537);
		ASSERT_EQ(de->new_chunk, 532);
		offset += sizeof(struct disk_exception);

		de = reinterpret_cast<struct disk_exception>((char)buffer + offset);
		ASSERT_EQ(de->old_chunk, 22);
		ASSERT_EQ(de->new_chunk, 538);
		ASSERT_EQ(de->new_chunk, 533);
		offset += sizeof(struct disk_exception);

		de = reinterpret_cast<struct disk_exception>((char)buffer + offset);
		ASSERT_EQ(de->old_chunk, 23);
		ASSERT_EQ(de->new_chunk, 539);
		ASSERT_EQ(de->new_chunk, 534);
		offset += sizeof(struct disk_exception);

		// End of metadata
		@@ -945,6 +1097,38 @@ TEST(Snapuserd_Test, ReadDmUserBlockWithoutDaemon) {
		harness.ReadDmUserBlockWithoutDaemon();
		}

		TEST(Snapuserd_Test, Snapshot_Merge_Crash_Fixed_Ordered) {
		CowSnapuserdTest harness;
		ASSERT_TRUE(harness.SetupOrderedOps());
		harness.MergeInterruptFixed(300);
		harness.ValidateMerge();
		harness.Shutdown();
		}

		TEST(Snapuserd_Test, Snapshot_Merge_Crash_Random_Ordered) {
		CowSnapuserdTest harness;
		ASSERT_TRUE(harness.SetupOrderedOps());
		harness.MergeInterruptRandomly(500);
		harness.ValidateMerge();
		harness.Shutdown();
		}

		TEST(Snapuserd_Test, Snapshot_Merge_Crash_Fixed_Inverted) {
		CowSnapuserdTest harness;
		ASSERT_TRUE(harness.SetupOrderedOpsInverted());
		harness.MergeInterruptFixed(50);
		harness.ValidateMerge();
		harness.Shutdown();
		}

		TEST(Snapuserd_Test, Snapshot_Merge_Crash_Random_Inverted) {
		CowSnapuserdTest harness;
		ASSERT_TRUE(harness.SetupOrderedOpsInverted());
		harness.MergeInterruptRandomly(50);
		harness.ValidateMerge();
		harness.Shutdown();
		}

		} // namespace snapshot
		} // namespace android

fs_mgr/libsnapshot/snapuserd/snapuserd.cpp

+18 −70

Original line number	Diff line number	Diff line
		@@ -436,8 +436,9 @@ bool Snapuserd::ReadMetadata() {

		int num_ra_ops_per_iter = ((GetBufferDataSize()) / BLOCK_SZ);
		std::optional<chunk_t> prev_id = {};
		std::map<uint64_t, const CowOperation*> map;
		std::vector<const CowOperation*> vec;
		std::set<uint64_t> dest_blocks;
		std::set<uint64_t> source_blocks;
		size_t pending_copy_ops = exceptions_per_area_ - num_ops;
		uint64_t total_copy_ops = reader_->get_num_ordered_ops_to_merge();

		@@ -491,99 +492,45 @@ bool Snapuserd::ReadMetadata() {
		// scratch space and re-construct it thereby there
		// is no loss of data.
		//
		// Note that we will follow the same order of COW operations
		// as present in the COW file. This will make sure that
		// the merge of operations are done based on the ops present
		// in the file.
		//===========================================================
		//
		// Case 2:
		//
		// Let's say we have three copy operations written to COW file
		// in the following order:
		//
		// op-1: 15 -> 18
		// op-2: 16 -> 19
		// op-3: 17 -> 20
		//
		// As aforementioned, kernel will initiate merge in reverse order.
		// Hence, we will read these ops in reverse order so that all these
		// ops are exectued in the same order as requested. Thus, we will
		// read the metadata in reverse order and for the kernel it will
		// look like:
		//
		// op-3: 17 -> 20
		// op-2: 16 -> 19
		// op-1: 15 -> 18 <-- Merge starts here in the kernel
		//
		// Now, this is problematic as kernel cannot batch merge them.
		//
		// Merge sequence will look like:
		//
		// Merge-1: op-1: 15 -> 18
		// Merge-2: op-2: 16 -> 19
		// Merge-3: op-3: 17 -> 20
		//
		// We have three merge operations.
		//
		// Even though the blocks are contiguous, kernel can batch merge
		// them if the blocks are in descending order. Update engine
		// addresses this issue partially for overlapping operations as
		// we see that op-1 to op-3 and op-4 to op-6 operatiosn are in
		// descending order. However, if the copy operations are not
		// overlapping, update engine cannot write these blocks
		// in descending order. Hence, we will try to address it.
		// Thus, we will send these blocks to the kernel and it will
		// look like:
		//
		// op-3: 15 -> 18
		// op-2: 16 -> 19
		// op-1: 17 -> 20 <-- Merge starts here in the kernel
		//
		// Now with this change, we can batch merge all these three
		// operations. Merge sequence will look like:
		//
		// Merge-1: {op-1: 17 -> 20, op-2: 16 -> 19, op-3: 15 -> 18}
		//
		// Note that we have changed the ordering of merge; However, this
		// is ok as each of these copy operations are independent and there
		// is no overlap.
		//
		//===================================================================
		if (prev_id.has_value()) {
		chunk_t diff = (cow_op->new_block > prev_id.value())
		? (cow_op->new_block - prev_id.value())
		: (prev_id.value() - cow_op->new_block);
		if (diff != 1) {
		break;
		}

		if (dest_blocks.count(cow_op->new_block) \|\| map.count(cow_op->source) > 0) {
		if (dest_blocks.count(cow_op->new_block) \|\| source_blocks.count(cow_op->source)) {
		break;
		}
		}
		metadata_found = true;
		pending_copy_ops -= 1;
		map[cow_op->new_block] = cow_op;
		vec.push_back(cow_op);
		dest_blocks.insert(cow_op->source);
		source_blocks.insert(cow_op->new_block);
		prev_id = cow_op->new_block;
		cowop_rm_iter->Next();
		} while (!cowop_rm_iter->Done() && pending_copy_ops);

		data_chunk_id = GetNextAllocatableChunkId(data_chunk_id);
		SNAP_LOG(DEBUG) << "Batch Merge copy-ops of size: " << map.size()
		SNAP_LOG(DEBUG) << "Batch Merge copy-ops of size: " << vec.size()
		<< " Area: " << vec_.size() << " Area offset: " << offset
		<< " Pending-copy-ops in this area: " << pending_copy_ops;

		for (auto it = map.begin(); it != map.end(); it++) {
		for (size_t i = 0; i < vec.size(); i++) {
		struct disk_exception* de =
		reinterpret_cast<struct disk_exception>((char)de_ptr.get() + offset);
		de->old_chunk = it->first;
		const CowOperation* cow_op = vec[i];

		de->old_chunk = cow_op->new_block;
		de->new_chunk = data_chunk_id;

		// Store operation pointer.
		chunk_vec_.push_back(std::make_pair(ChunkToSector(data_chunk_id), it->second));
		chunk_vec_.push_back(std::make_pair(ChunkToSector(data_chunk_id), cow_op));
		offset += sizeof(struct disk_exception);
		num_ops += 1;
		copy_ops++;
		if (read_ahead_feature_) {
		read_ahead_ops_.push_back(it->second);
		read_ahead_ops_.push_back(cow_op);
		}

		SNAP_LOG(DEBUG) << num_ops << ":"
		@@ -626,8 +573,9 @@ bool Snapuserd::ReadMetadata() {
		data_chunk_id = GetNextAllocatableChunkId(data_chunk_id);
		}
		}
		map.clear();
		vec.clear();
		dest_blocks.clear();
		source_blocks.clear();
		prev_id.reset();
		}