Merge "libsnapshot:snapuserd: Snapshot merge support." (d29c2f5d) · Commits · e / os / android_system_core

fs_mgr/libsnapshot/cow_reader.cpp

+20 −0

Original line number	Diff line number	Diff line
		@@ -193,6 +193,26 @@ bool CowReader::ParseOps() {
		} else {
		LOG(INFO) << "No Footer, recovered data";
		}

		if (header_.num_merge_ops > 0) {
		uint64_t merge_ops = header_.num_merge_ops;
		uint64_t metadata_ops = 0;
		current_op_num = 0;

		CHECK(ops_buffer->size() >= merge_ops);
		while (merge_ops) {
		auto& current_op = ops_buffer->data()[current_op_num];
		if (current_op.type == kCowLabelOp \|\| current_op.type == kCowFooterOp) {
		metadata_ops += 1;
		} else {
		merge_ops -= 1;
		}
		current_op_num += 1;
		}
		ops_buffer->erase(ops_buffer.get()->begin(),
		ops_buffer.get()->begin() + header_.num_merge_ops + metadata_ops);
		}

		ops_ = ops_buffer;
		return true;
		}

fs_mgr/libsnapshot/cow_writer.cpp

+29 −0

Original line number	Diff line number	Diff line
		@@ -91,6 +91,7 @@ void CowWriter::SetupHeaders() {
		header_.header_size = sizeof(CowHeader);
		header_.footer_size = sizeof(CowFooter);
		header_.block_size = options_.block_size;
		header_.num_merge_ops = 0;
		footer_ = {};
		footer_.op.data_length = 64;
		footer_.op.type = kCowFooterOp;
		@@ -125,6 +126,12 @@ bool CowWriter::SetFd(android::base::borrowed_fd fd) {
		return true;
		}

		void CowWriter::InitializeMerge(borrowed_fd fd, CowHeader* header) {
		fd_ = fd;
		memcpy(&header_, header, sizeof(CowHeader));
		merge_in_progress_ = true;
		}

		bool CowWriter::Initialize(unique_fd&& fd) {
		owned_fd_ = std::move(fd);
		return Initialize(borrowed_fd{owned_fd_});
		@@ -223,6 +230,7 @@ bool CowWriter::OpenForAppend(uint64_t label) {
		}

		bool CowWriter::EmitCopy(uint64_t new_block, uint64_t old_block) {
		CHECK(!merge_in_progress_);
		CowOperation op = {};
		op.type = kCowCopyOp;
		op.new_block = new_block;
		@@ -233,6 +241,7 @@ bool CowWriter::EmitCopy(uint64_t new_block, uint64_t old_block) {
		bool CowWriter::EmitRawBlocks(uint64_t new_block_start, const void* data, size_t size) {
		const uint8_t* iter = reinterpret_cast<const uint8_t*>(data);
		uint64_t pos;
		CHECK(!merge_in_progress_);
		for (size_t i = 0; i < size / header_.block_size; i++) {
		CowOperation op = {};
		op.type = kCowReplaceOp;
		@@ -271,6 +280,7 @@ bool CowWriter::EmitRawBlocks(uint64_t new_block_start, const void* data, size_t
		}

		bool CowWriter::EmitZeroBlocks(uint64_t new_block_start, uint64_t num_blocks) {
		CHECK(!merge_in_progress_);
		for (uint64_t i = 0; i < num_blocks; i++) {
		CowOperation op = {};
		op.type = kCowZeroOp;
		@@ -282,6 +292,7 @@ bool CowWriter::EmitZeroBlocks(uint64_t new_block_start, uint64_t num_blocks) {
		}

		bool CowWriter::EmitLabel(uint64_t label) {
		CHECK(!merge_in_progress_);
		CowOperation op = {};
		op.type = kCowLabelOp;
		op.source = label;
		@@ -416,5 +427,23 @@ bool CowWriter::Sync() {
		return true;
		}

		bool CowWriter::CommitMerge(int merged_ops) {
		CHECK(merge_in_progress_);
		header_.num_merge_ops += merged_ops;

		if (lseek(fd_.get(), 0, SEEK_SET) < 0) {
		PLOG(ERROR) << "lseek failed";
		return false;
		}

		if (!android::base::WriteFully(fd_, reinterpret_cast<const uint8_t*>(&header_),
		sizeof(header_))) {
		PLOG(ERROR) << "WriteFully failed";
		return false;
		}

		return Sync();
		}

		} // namespace snapshot
		} // namespace android

fs_mgr/libsnapshot/include/libsnapshot/cow_format.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -59,6 +59,9 @@ struct CowHeader {

		// The size of block operations, in bytes.
		uint32_t block_size;

		// Tracks merge operations completed
		uint64_t num_merge_ops;
		} __attribute__((packed));

		// This structure is the same size of a normal Operation, but is repurposed for the footer.

fs_mgr/libsnapshot/include/libsnapshot/cow_reader.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -135,6 +135,8 @@ class CowReader : public ICowReader {

		bool GetRawBytes(uint64_t offset, void* buffer, size_t len, size_t* read);

		void UpdateMergeProgress(uint64_t merge_ops) { header_.num_merge_ops += merge_ops; }

		private:
		bool ParseOps();

fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -97,6 +97,9 @@ class CowWriter : public ICowWriter {
		bool InitializeAppend(android::base::unique_fd&&, uint64_t label);
		bool InitializeAppend(android::base::borrowed_fd fd, uint64_t label);

		void InitializeMerge(android::base::borrowed_fd fd, CowHeader* header);
		bool CommitMerge(int merged_ops);

		bool Finalize() override;

		uint64_t GetCowSize() override;
		@@ -129,6 +132,7 @@ class CowWriter : public ICowWriter {
		int compression_ = 0;
		uint64_t next_op_pos_ = 0;
		bool is_dev_null_ = false;
		bool merge_in_progress_ = false;

		// :TODO: this is not efficient, but stringstream ubsan aborts because some
		// bytes overflow a signed char.