Merge "libsnapshot: Fetch device size from header" into main (74287053) · Commits · e / os / android_system_core

fs_mgr/libsnapshot/snapshot.cpp

+10 −7

Original line number	Diff line number	Diff line
		@@ -508,8 +508,6 @@ bool SnapshotManager::MapDmUserCow(LockedFile* lock, const std::string& name,
		// When snapshots are on current slot, we determine the size
		// of block device based on the number of COW operations. We cannot
		// use base device as it will be from older image.
		size_t num_ops = 0;
		uint64_t dev_sz = 0;
		unique_fd fd(open(cow_file.c_str(), O_RDONLY \| O_CLOEXEC));
		if (fd < 0) {
		PLOG(ERROR) << "Failed to open " << cow_file;
		@@ -522,13 +520,18 @@ bool SnapshotManager::MapDmUserCow(LockedFile* lock, const std::string& name,
		return false;
		}

		uint64_t dev_sz = 0;
		const auto& header = reader.GetHeader();
		if (header.prefix.major_version > 2) {
		LOG(ERROR) << "COW format not supported";
		return false;
		}
		num_ops = reader.get_num_total_data_ops();
		if (header.prefix.major_version == 2) {
		const size_t num_ops = reader.get_num_total_data_ops();
		dev_sz = (num_ops * header.block_size);
		} else {
		// create_snapshot will skip in-place copy ops. Hence, fetch this
		// information directly from v3 header.
		const auto& v3_header = reader.header_v3();
		dev_sz = v3_header.op_count_max * v3_header.block_size;
		}

		base_sectors = dev_sz >> 9;
		} else {
		// For userspace snapshots, the size of the base device is taken as the