libsnapshot: Refactor CreateLogicalAndSnapshotPartitions (31fda7e4) · Commits · e / os / android_system_core

fs_mgr/libsnapshot/include/libsnapshot/snapshot.h

+4 −0

Original line number	Original line	Diff line number	Diff line
	@@ -329,6 +329,10 @@ class SnapshotManager final {
	std::string GetSnapshotDeviceName(const std::string& snapshot_name,		std::string GetSnapshotDeviceName(const std::string& snapshot_name,
	const SnapshotStatus& status);		const SnapshotStatus& status);

			// Map the base device, COW devices, and snapshot device.
			bool MapPartitionWithSnapshot(LockedFile* lock, CreateLogicalPartitionParams params,
			std::string* path);

	std::string gsid_dir_;		std::string gsid_dir_;
	std::string metadata_dir_;		std::string metadata_dir_;
	std::unique_ptr<IDeviceInfo> device_;		std::unique_ptr<IDeviceInfo> device_;

fs_mgr/libsnapshot/snapshot.cpp

+82 −54

Original line number	Original line	Diff line number	Diff line
	@@ -19,6 +19,7 @@
	#include <sys/types.h>		#include <sys/types.h>
	#include <sys/unistd.h>		#include <sys/unistd.h>

			#include <optional>
	#include <thread>		#include <thread>
	#include <unordered_set>		#include <unordered_set>

	@@ -1102,22 +1103,6 @@ bool SnapshotManager::CreateLogicalAndSnapshotPartitions(const std::string& supe
	auto lock = LockExclusive();		auto lock = LockExclusive();
	if (!lock) return false;		if (!lock) return false;

	std::vector<std::string> snapshot_list;
	if (!ListSnapshots(lock.get(), &snapshot_list)) {
	return false;
	}

	std::unordered_set<std::string> live_snapshots;
	for (const auto& snapshot : snapshot_list) {
	SnapshotStatus status;
	if (!ReadSnapshotStatus(lock.get(), snapshot, &status)) {
	return false;
	}
	if (status.state != SnapshotState::MergeCompleted) {
	live_snapshots.emplace(snapshot);
	}
	}

	const auto& opener = device_->GetPartitionOpener();		const auto& opener = device_->GetPartitionOpener();
	uint32_t slot = SlotNumberForSlotSuffix(device_->GetSlotSuffix());		uint32_t slot = SlotNumberForSlotSuffix(device_->GetSlotSuffix());
	auto metadata = android::fs_mgr::ReadMetadata(opener, super_device, slot);		auto metadata = android::fs_mgr::ReadMetadata(opener, super_device, slot);
	@@ -1126,45 +1111,86 @@ bool SnapshotManager::CreateLogicalAndSnapshotPartitions(const std::string& supe
	return false;		return false;
	}		}

	// Map logical partitions.
	auto& dm = DeviceMapper::Instance();
	for (const auto& partition : metadata->partitions) {		for (const auto& partition : metadata->partitions) {
	auto partition_name = GetPartitionName(partition);
	if (!partition.num_extents) {
	LOG(INFO) << "Skipping zero-length logical partition: " << partition_name;
	continue;
	}

	if (!(partition.attributes & LP_PARTITION_ATTR_UPDATED)) {
	LOG(INFO) << "Detected re-flashing of partition, will skip snapshot: "
	<< partition_name;
	live_snapshots.erase(partition_name);
	}

	CreateLogicalPartitionParams params = {		CreateLogicalPartitionParams params = {
	.block_device = super_device,		.block_device = super_device,
	.metadata = metadata.get(),		.metadata = metadata.get(),
	.partition = &partition,		.partition = &partition,
	.partition_opener = &opener,		.partition_opener = &opener,
	};		};
			std::string ignore_path;
			if (!MapPartitionWithSnapshot(lock.get(), std::move(params), &ignore_path)) {
			return false;
			}
			}

	if (auto iter = live_snapshots.find(partition_name); iter != live_snapshots.end()) {		LOG(INFO) << "Created logical partitions with snapshot.";
	// If the device has a snapshot, it'll need to be writable, and		return true;
	// we'll need to create the logical partition with a marked-up name		}
	// (since the snapshot will use the partition name).
			bool SnapshotManager::MapPartitionWithSnapshot(LockedFile* lock,
			CreateLogicalPartitionParams params,
			std::string* path) {
			CHECK(lock);
			path->clear();

			// Fill out fields in CreateLogicalPartitionParams so that we have more information (e.g. by
			// reading super partition metadata).
			CreateLogicalPartitionParams::OwnedData params_owned_data;
			if (!params.InitDefaults(&params_owned_data)) {
			return false;
			}

			if (!params.partition->num_extents) {
			LOG(INFO) << "Skipping zero-length logical partition: " << params.GetPartitionName();
			return true; // leave path empty to indicate that nothing is mapped.
			}

			// Determine if there is a live snapshot for the SnapshotStatus of the partition; i.e. if the
			// partition still has a snapshot that needs to be mapped. If no live snapshot or merge
			// completed, live_snapshot_status is set to nullopt.
			std::optional<SnapshotStatus> live_snapshot_status;
			do {
			if (!(params.partition->attributes & LP_PARTITION_ATTR_UPDATED)) {
			LOG(INFO) << "Detected re-flashing of partition, will skip snapshot: "
			<< params.GetPartitionName();
			break;
			}
			auto file_path = GetSnapshotStatusFilePath(params.GetPartitionName());
			if (access(file_path.c_str(), F_OK) != 0) {
			if (errno != ENOENT) {
			PLOG(INFO) << "Can't map snapshot for " << params.GetPartitionName()
			<< ": Can't access " << file_path;
			return false;
			}
			break;
			}
			live_snapshot_status = std::make_optional<SnapshotStatus>();
			if (!ReadSnapshotStatus(lock, params.GetPartitionName(), &*live_snapshot_status)) {
			return false;
			}
			// No live snapshot if merge is completed.
			if (live_snapshot_status->state == SnapshotState::MergeCompleted) {
			live_snapshot_status.reset();
			}
			} while (0);

			if (live_snapshot_status.has_value()) {
			// dm-snapshot requires the base device to be writable.
	params.force_writable = true;		params.force_writable = true;
	params.device_name = GetBaseDeviceName(partition_name);		// Map the base device with a different name to avoid collision.
			params.device_name = GetBaseDeviceName(params.GetPartitionName());
	}		}

			auto& dm = DeviceMapper::Instance();
	std::string ignore_path;		std::string ignore_path;
	if (!CreateLogicalPartition(params, &ignore_path)) {		if (!CreateLogicalPartition(params, &ignore_path)) {
	LOG(ERROR) << "Could not create logical partition " << partition_name << " as device "		LOG(ERROR) << "Could not create logical partition " << params.GetPartitionName()
	<< params.GetDeviceName();		<< " as device " << params.GetDeviceName();
	return false;		return false;
	}		}
	if (!params.force_writable) {		if (!live_snapshot_status.has_value()) {
	// No snapshot.		return true;
	continue;
	}		}

	// We don't have ueventd in first-stage init, so use device major:minor		// We don't have ueventd in first-stage init, so use device major:minor
	@@ -1174,11 +1200,13 @@ bool SnapshotManager::CreateLogicalAndSnapshotPartitions(const std::string& supe
	LOG(ERROR) << "Could not determine major/minor for: " << params.GetDeviceName();		LOG(ERROR) << "Could not determine major/minor for: " << params.GetDeviceName();
	return false;		return false;
	}		}
	if (!MapSnapshot(lock.get(), partition_name, base_device, {}, &ignore_path)) {		if (!MapSnapshot(lock, params.GetPartitionName(), base_device, {}, path)) {
	LOG(ERROR) << "Could not map snapshot for partition: " << partition_name;		LOG(ERROR) << "Could not map snapshot for partition: " << params.GetPartitionName();
	return false;		return false;
	}		}
	}
			LOG(INFO) << "Mapped " << params.GetPartitionName() << " as snapshot device at " << *path;

	return true;		return true;
	}		}