Support batch writes for V3 cow format (557104c8) · Commits · e / os / android_system_core

fs_mgr/libsnapshot/libsnapshot_cow/writer_v3.cpp

+66 −37

Original line number	Diff line number	Diff line
		@@ -38,6 +38,7 @@
		#include <linux/fs.h>
		#include <sys/ioctl.h>
		#include <unistd.h>
		#include <numeric>

		// The info messages here are spammy, but as useful for update_engine. Disable
		// them when running on the host.
		@@ -55,7 +56,7 @@ static_assert(sizeof(off_t) == sizeof(uint64_t));
		using android::base::unique_fd;

		CowWriterV3::CowWriterV3(const CowOptions& options, unique_fd&& fd)
		: CowWriterBase(options, std::move(fd)) {
		: CowWriterBase(options, std::move(fd)), batch_size_(std::max<size_t>(options.cluster_ops, 1)) {
		SetupHeaders();
		}

		@@ -70,6 +71,9 @@ void CowWriterV3::SetupHeaders() {
		header_.block_size = options_.block_size;
		header_.num_merge_ops = options_.num_merge_ops;
		header_.cluster_ops = 0;
		if (batch_size_ > 1) {
		LOG(INFO) << "Batch writes enabled with batch size of " << batch_size_;
		}
		if (options_.scratch_space) {
		header_.buffer_size = BUFFER_REGION_DEFAULT_SIZE;
		}
		@@ -258,40 +262,49 @@ bool CowWriterV3::EmitBlocks(uint64_t new_block_start, const void* data, size_t
		}
		op.data_length = header_.block_size;
		}
		return WriteOperation({ops.data(), ops.size()},
		{reinterpret_cast<const uint8_t*>(data), size});
		return WriteOperation({ops.data(), ops.size()}, data, size);
		}

		const auto saved_op_count = header_.op_count;
		const auto saved_data_pos = next_data_pos_;
		for (size_t i = 0; i < num_blocks; i++) {
		for (size_t i = 0; i < num_blocks; i += batch_size_) {
		const auto blocks_to_write = std::min<size_t>(batch_size_, num_blocks - i);
		std::vector<std::basic_string<uint8_t>> compressed_blocks(blocks_to_write);
		std::vector<CowOperationV3> ops(blocks_to_write);
		std::vector<struct iovec> vec(blocks_to_write);
		size_t compressed_bytes = 0;
		for (size_t j = 0; j < blocks_to_write; j++) {
		const uint8_t* const iter =
		reinterpret_cast<const uint8_t>(data) + (header_.block_size i);
		reinterpret_cast<const uint8_t>(data) + (header_.block_size (i + j));

		CowOperation op{};
		op.new_block = new_block_start + i;
		CowOperation& op = ops[j];
		op.new_block = new_block_start + i + j;

		op.set_type(type);
		if (type == kCowXorOp) {
		op.set_source((old_block + i) * header_.block_size + offset);
		op.set_source((old_block + i + j) * header_.block_size + offset);
		} else {
		op.set_source(next_data_pos_);
		op.set_source(next_data_pos_ + compressed_bytes);
		}
		const void* out_data = iter;

		op.data_length = header_.block_size;

		const std::basic_string<uint8_t> compressed_data =
		compressor_->Compress(out_data, header_.block_size);
		if (compressed_data.size() < op.data_length) {
		out_data = compressed_data.data();
		op.data_length = compressed_data.size();
		std::basic_string<uint8_t> compressed_data =
		compressor_->Compress(iter, header_.block_size);
		if (compressed_data.empty()) {
		LOG(ERROR) << "Compression failed during EmitBlocks(" << new_block_start << ", "
		<< num_blocks << ");";
		return false;
		}
		if (!WriteOperation(op, out_data, op.data_length)) {
		if (compressed_data.size() >= header_.block_size) {
		compressed_data.resize(header_.block_size);
		std::memcpy(compressed_data.data(), iter, header_.block_size);
		}
		compressed_blocks[j] = std::move(compressed_data);
		vec[j] = {.iov_base = compressed_blocks[j].data(),
		.iov_len = compressed_blocks[j].size()};
		op.data_length = vec[j].iov_len;
		compressed_bytes += op.data_length;
		}
		if (!WriteOperation({ops.data(), ops.size()}, {vec.data(), vec.size()})) {
		PLOG(ERROR) << "AddRawBlocks with compression: write failed. new block: "
		<< new_block_start << " compression: " << compression_.algorithm;
		header_.op_count = saved_op_count;
		next_data_pos_ = saved_data_pos;
		return false;
		}
		}
		@@ -299,14 +312,14 @@ bool CowWriterV3::EmitBlocks(uint64_t new_block_start, const void* data, size_t
		return true;
		}

		bool CowWriterV3::EmitZeroBlocks(uint64_t new_block_start, uint64_t num_blocks) {
		bool CowWriterV3::EmitZeroBlocks(uint64_t new_block_start, const uint64_t num_blocks) {
		std::vector<CowOperationV3> ops(num_blocks);
		for (uint64_t i = 0; i < num_blocks; i++) {
		CowOperationV3& op = ops[i];
		for (uint64_t i = 0; i < ops.size(); i++) {
		auto& op = ops[i];
		op.set_type(kCowZeroOp);
		op.new_block = new_block_start + i;
		}
		if (!WriteOperation({ops.data(), ops.size()}, {})) {
		if (!WriteOperation({ops.data(), ops.size()})) {
		return false;
		}
		return true;
		@@ -353,8 +366,23 @@ bool CowWriterV3::EmitSequenceData(size_t num_ops, const uint32_t* data) {
		return true;
		}

		bool CowWriterV3::WriteOperation(std::basic_string_view<CowOperationV3> op, const void* data,
		size_t size) {
		struct iovec vec {
		.iov_len = size
		};
		// Dear C++ god, this is effectively a const_cast. I had to do this because
		// pwritev()'s struct iovec requires a non-const pointer. The input data
		// will not be modified, as the iovec is only used for a write operation.
		std::memcpy(&vec.iov_base, &data, sizeof(data));
		return WriteOperation(op, {&vec, 1});
		}

		bool CowWriterV3::WriteOperation(std::basic_string_view<CowOperationV3> ops,
		std::basic_string_view<uint8_t> data) {
		std::basic_string_view<struct iovec> data) {
		const auto total_data_size =
		std::transform_reduce(data.begin(), data.end(), 0, std::plus<size_t>{},
		[](const struct iovec& a) { return a.iov_len; });
		if (IsEstimating()) {
		header_.op_count += ops.size();
		if (header_.op_count > header_.op_count_max) {
		@@ -363,7 +391,7 @@ bool CowWriterV3::WriteOperation(std::basic_string_view<CowOperationV3> ops,
		next_data_pos_ += (header_.op_count - header_.op_count_max) * sizeof(CowOperationV3);
		header_.op_count_max = header_.op_count;
		}
		next_data_pos_ += data.size();
		next_data_pos_ += total_data_size;
		return true;
		}

		@@ -379,20 +407,21 @@ bool CowWriterV3::WriteOperation(std::basic_string_view<CowOperationV3> ops,
		return false;
		}
		if (!data.empty()) {
		if (!android::base::WriteFullyAtOffset(fd_, data.data(), data.size(), next_data_pos_)) {
		const auto ret = pwritev(fd_, data.data(), data.size(), next_data_pos_);
		if (ret != total_data_size) {
		PLOG(ERROR) << "write failed for data of size: " << data.size()
		<< " at offset: " << next_data_pos_;
		<< " at offset: " << next_data_pos_ << " " << ret;
		return false;
		}
		}
		header_.op_count += ops.size();
		next_data_pos_ += data.size();
		next_data_pos_ += total_data_size;

		return true;
		}

		bool CowWriterV3::WriteOperation(const CowOperationV3& op, const void* data, size_t size) {
		return WriteOperation({&op, 1}, {reinterpret_cast<const uint8_t*>(data), size});
		return WriteOperation({&op, 1}, data, size);
		}

		bool CowWriterV3::Finalize() {

fs_mgr/libsnapshot/libsnapshot_cow/writer_v3.h

+4 −1

Original line number	Diff line number	Diff line
		@@ -46,7 +46,9 @@ class CowWriterV3 : public CowWriterBase {
		bool OpenForWrite();
		bool OpenForAppend(uint64_t label);
		bool WriteOperation(std::basic_string_view<CowOperationV3> op,
		std::basic_string_view<uint8_t> data);
		std::basic_string_view<struct iovec> data);
		bool WriteOperation(std::basic_string_view<CowOperationV3> op, const void* data = nullptr,
		size_t size = 0);
		bool WriteOperation(const CowOperationV3& op, const void* data = nullptr, size_t size = 0);
		bool EmitBlocks(uint64_t new_block_start, const void* data, size_t size, uint64_t old_block,
		uint16_t offset, CowOperationType type);
		@@ -68,6 +70,7 @@ class CowWriterV3 : public CowWriterBase {
		// in the case that we are using one thread for compression, we can store and re-use the same
		// compressor
		int num_compress_threads_ = 1;
		size_t batch_size_ = 0;
		};

		} // namespace snapshot