Merge "libsnapshot: Track the source slot across reboots." (49ea4d95) · Commits · e / os / android_system_core

fs_mgr/libsnapshot/Android.bp

+1 −0

Original line number	Diff line number	Diff line
		@@ -33,6 +33,7 @@ cc_defaults {
		"libext2_uuid",
		"libext4_utils",
		"libfiemap",
		"libfstab",
		],
		export_include_dirs: ["include"],
		}

fs_mgr/libsnapshot/include/libsnapshot/snapshot.h

+9 −5

Original line number	Diff line number	Diff line
		@@ -71,11 +71,7 @@ class SnapshotManager final {
		virtual ~IDeviceInfo() {}
		virtual std::string GetGsidDir() const = 0;
		virtual std::string GetMetadataDir() const = 0;

		// Return true if the device is currently running off snapshot devices,
		// indicating that we have booted after applying (but not merging) an
		// OTA.
		virtual bool IsRunningSnapshot() const = 0;
		virtual std::string GetSlotSuffix() const = 0;
		};

		~SnapshotManager();
		@@ -93,6 +89,11 @@ class SnapshotManager final {
		// state != Initiated or None.
		bool CancelUpdate();

		// Mark snapshot writes as having completed. After this, new snapshots cannot
		// be created, and the device must either cancel the OTA (either before
		// rebooting or after rolling back), or merge the OTA.
		bool FinishedSnapshotWrites();

		// Initiate a merge on all snapshot devices. This should only be used after an
		// update has been marked successful after booting.
		bool InitiateMerge();
		@@ -261,6 +262,9 @@ class SnapshotManager final {
		bool ReadSnapshotStatus(LockedFile* lock, const std::string& name, SnapshotStatus* status);
		std::string GetSnapshotStatusFilePath(const std::string& name);

		std::string GetSnapshotBootIndicatorPath();
		void RemoveSnapshotBootIndicator();

		// Return the name of the device holding the "snapshot" or "snapshot-merge"
		// target. This may not be the final device presented via MapSnapshot(), if
		// for example there is a linear segment.

fs_mgr/libsnapshot/snapshot.cpp

+51 −8

Original line number	Diff line number	Diff line
		@@ -27,6 +27,7 @@
		#include <android-base/strings.h>
		#include <android-base/unique_fd.h>
		#include <ext4_utils/ext4_utils.h>
		#include <fstab/fstab.h>
		#include <libdm/dm.h>
		#include <libfiemap/image_manager.h>

		@@ -48,18 +49,15 @@ using namespace std::string_literals;
		// Unit is sectors, this is a 4K chunk.
		static constexpr uint32_t kSnapshotChunkSize = 8;

		static constexpr char kSnapshotBootIndicatorFile[] = "snapshot-boot";

		class DeviceInfo final : public SnapshotManager::IDeviceInfo {
		public:
		std::string GetGsidDir() const override { return "ota"s; }
		std::string GetMetadataDir() const override { return "/metadata/ota"s; }
		bool IsRunningSnapshot() const override;
		std::string GetSlotSuffix() const override { return fs_mgr_get_slot_suffix(); }
		};

		bool DeviceInfo::IsRunningSnapshot() const {
		// :TODO: implement this check.
		return true;
		}

		// Note: IIMageManager is an incomplete type in the header, so the default
		// destructor doesn't work.
		SnapshotManager::~SnapshotManager() {}
		@@ -115,6 +113,27 @@ bool SnapshotManager::CancelUpdate() {
		return true;
		}

		bool SnapshotManager::FinishedSnapshotWrites() {
		auto lock = LockExclusive();
		if (!lock) return false;

		if (ReadUpdateState(lock.get()) != UpdateState::Initiated) {
		LOG(ERROR) << "Can only transition to the Unverified state from the Initiated state.";
		return false;
		}

		// This file acts as both a quick indicator for init (it can use access(2)
		// to decide how to do first-stage mounts), and it stores the old slot, so
		// we can tell whether or not we performed a rollback.
		auto contents = device_->GetSlotSuffix();
		auto boot_file = GetSnapshotBootIndicatorPath();
		if (!android::base::WriteStringToFile(contents, boot_file)) {
		PLOG(ERROR) << "write failed: " << boot_file;
		return false;
		}
		return WriteUpdateState(lock.get(), UpdateState::Unverified);
		}

		bool SnapshotManager::CreateSnapshot(LockedFile* lock, const std::string& name,
		uint64_t device_size, uint64_t snapshot_size,
		uint64_t cow_size) {
		@@ -339,8 +358,16 @@ bool SnapshotManager::InitiateMerge() {
		LOG(ERROR) << "Cannot begin a merge if an update has not been verified";
		return false;
		}
		if (!device_->IsRunningSnapshot()) {
		LOG(ERROR) << "Cannot begin a merge if the device is not booted off a snapshot";

		std::string old_slot;
		auto boot_file = GetSnapshotBootIndicatorPath();
		if (!android::base::ReadFileToString(boot_file, &old_slot)) {
		LOG(ERROR) << "Could not determine the previous slot; aborting merge";
		return false;
		}
		auto new_slot = device_->GetSlotSuffix();
		if (new_slot == old_slot) {
		LOG(ERROR) << "Device cannot merge while booting off old slot " << old_slot;
		return false;
		}

		@@ -676,7 +703,23 @@ UpdateState SnapshotManager::CheckTargetMergeState(LockedFile* lock, const std::
		return UpdateState::MergeCompleted;
		}

		std::string SnapshotManager::GetSnapshotBootIndicatorPath() {
		return metadata_dir_ + "/" + kSnapshotBootIndicatorFile;
		}

		void SnapshotManager::RemoveSnapshotBootIndicator() {
		// It's okay if this fails - first-stage init performs a deeper check after
		// reading the indicator file, so it's not a problem if it still exists
		// after the update completes.
		auto boot_file = GetSnapshotBootIndicatorPath();
		if (unlink(boot_file.c_str()) == -1 && errno != ENOENT) {
		PLOG(ERROR) << "unlink " << boot_file;
		}
		}

		void SnapshotManager::AcknowledgeMergeSuccess(LockedFile* lock) {
		RemoveSnapshotBootIndicator();

		if (!WriteUpdateState(lock, UpdateState::None)) {
		// We'll try again next reboot, ad infinitum.
		return;

fs_mgr/libsnapshot/snapshot_test.cpp

+10 −17

Original line number	Diff line number	Diff line
		@@ -43,12 +43,12 @@ class TestDeviceInfo : public SnapshotManager::IDeviceInfo {
		public:
		std::string GetGsidDir() const override { return "ota/test"s; }
		std::string GetMetadataDir() const override { return "/metadata/ota/test"s; }
		bool IsRunningSnapshot() const override { return is_running_snapshot_; }
		std::string GetSlotSuffix() const override { return slot_suffix_; }

		void set_is_running_snapshot(bool value) { is_running_snapshot_ = value; }
		void set_slot_suffix(const std::string& suffix) { slot_suffix_ = suffix; }

		private:
		bool is_running_snapshot_;
		std::string slot_suffix_;
		};

		std::unique_ptr<SnapshotManager> sm;
		@@ -60,7 +60,7 @@ class SnapshotTest : public ::testing::Test {

		protected:
		void SetUp() override {
		test_device->set_is_running_snapshot(false);
		test_device->set_slot_suffix("_a");

		if (sm->GetUpdateState() != UpdateState::None) {
		CleanupTestArtifacts();
		@@ -189,15 +189,9 @@ TEST_F(SnapshotTest, MapPartialSnapshot) {
		}

		TEST_F(SnapshotTest, NoMergeBeforeReboot) {
		ASSERT_TRUE(AcquireLock());

		// Set the state to Unverified, as if we finished an update.
		ASSERT_TRUE(sm->WriteUpdateState(lock_.get(), UpdateState::Unverified));
		ASSERT_TRUE(sm->FinishedSnapshotWrites());

		// Release the lock.
		lock_ = nullptr;

		// Merge should fail, since we didn't mark the device as rebooted.
		// Merge should fail, since the slot hasn't changed.
		ASSERT_FALSE(sm->InitiateMerge());
		}

		@@ -231,7 +225,7 @@ TEST_F(SnapshotTest, Merge) {
		// Release the lock.
		lock_ = nullptr;

		test_device->set_is_running_snapshot(true);
		test_device->set_slot_suffix("_b");
		ASSERT_TRUE(sm->InitiateMerge());

		// The device should have been switched to a snapshot-merge target.
		@@ -273,13 +267,12 @@ TEST_F(SnapshotTest, MergeCannotRemoveCow) {
		unique_fd fd(open(cow_path.c_str(), O_RDONLY \| O_CLOEXEC));
		ASSERT_GE(fd, 0);

		// Set the state to Unverified, as if we finished an update.
		ASSERT_TRUE(sm->WriteUpdateState(lock_.get(), UpdateState::Unverified));

		// Release the lock.
		lock_ = nullptr;

		test_device->set_is_running_snapshot(true);
		ASSERT_TRUE(sm->FinishedSnapshotWrites());

		test_device->set_slot_suffix("_b");
		ASSERT_TRUE(sm->InitiateMerge());

		// COW cannot be removed due to open fd, so expect a soft failure.