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// Copyright (C) 2019 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include <libsnapshot/snapshot.h>
#include <dirent.h>
#include <fcntl.h>
#include <math.h>
#include <sys/file.h>
#include <sys/types.h>
#include <sys/unistd.h>
#include <optional>
#include <thread>
#include <unordered_set>
#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/parseint.h>
#include <android-base/properties.h>
#include <android-base/strings.h>
#include <android-base/unique_fd.h>
#include <cutils/sockets.h>
#include <ext4_utils/ext4_utils.h>
#include <fs_mgr.h>
#include <fs_mgr/file_wait.h>
#include <fs_mgr_dm_linear.h>
#include <fstab/fstab.h>
#include <libdm/dm.h>
#include <libfiemap/image_manager.h>
#include <liblp/liblp.h>
#include <android/snapshot/snapshot.pb.h>
#include <libsnapshot/snapshot_stats.h>
#include "device_info.h"
#include "partition_cow_creator.h"
#include "snapshot_metadata_updater.h"
#include "snapshot_reader.h"
#include "utility.h"
namespace android {
namespace snapshot {
using android::base::unique_fd;
using android::dm::DeviceMapper;
using android::dm::DmDeviceState;
using android::dm::DmTable;
using android::dm::DmTargetLinear;
using android::dm::DmTargetSnapshot;
using android::dm::DmTargetUser;
using android::dm::kSectorSize;
using android::dm::SnapshotStorageMode;
using android::fiemap::FiemapStatus;
using android::fiemap::IImageManager;
using android::fs_mgr::CreateDmTable;
using android::fs_mgr::CreateLogicalPartition;
using android::fs_mgr::CreateLogicalPartitionParams;
using android::fs_mgr::GetPartitionGroupName;
using android::fs_mgr::GetPartitionName;
using android::fs_mgr::LpMetadata;
using android::fs_mgr::MetadataBuilder;
using android::fs_mgr::SlotNumberForSlotSuffix;
using android::hardware::boot::V1_1::MergeStatus;
using chromeos_update_engine::DeltaArchiveManifest;
using chromeos_update_engine::Extent;
using chromeos_update_engine::FileDescriptor;
using chromeos_update_engine::PartitionUpdate;
template <typename T>
using RepeatedPtrField = google::protobuf::RepeatedPtrField<T>;
using std::chrono::duration_cast;
using namespace std::chrono_literals;
using namespace std::string_literals;
static constexpr char kBootIndicatorPath[] = "/metadata/ota/snapshot-boot";
static constexpr char kRollbackIndicatorPath[] = "/metadata/ota/rollback-indicator";
static constexpr auto kUpdateStateCheckInterval = 2s;
// Note: IImageManager is an incomplete type in the header, so the default
// destructor doesn't work.
SnapshotManager::~SnapshotManager() {}
std::unique_ptr<SnapshotManager> SnapshotManager::New(IDeviceInfo* info) {
if (!info) {
info = new DeviceInfo();
}
return std::unique_ptr<SnapshotManager>(new SnapshotManager(info));
}
std::unique_ptr<SnapshotManager> SnapshotManager::NewForFirstStageMount(IDeviceInfo* info) {
auto sm = New(info);
if (!sm || !sm->ForceLocalImageManager()) {
return nullptr;
}
// The first-stage version of snapuserd is explicitly started by init. Do
// not attempt to using it during tests (which run in normal AOSP).
if (!sm->device()->IsTestDevice()) {
sm->use_first_stage_snapuserd_ = true;
}
return sm;
}
SnapshotManager::SnapshotManager(IDeviceInfo* device) : device_(device) {
gsid_dir_ = device_->GetGsidDir();
metadata_dir_ = device_->GetMetadataDir();
}
static std::string GetCowName(const std::string& snapshot_name) {
return snapshot_name + "-cow";
}
static std::string GetDmUserCowName(const std::string& snapshot_name) {
return snapshot_name + "-user-cow";
}
static std::string GetCowImageDeviceName(const std::string& snapshot_name) {
return snapshot_name + "-cow-img";
}
static std::string GetBaseDeviceName(const std::string& partition_name) {
return partition_name + "-base";
}
static std::string GetSnapshotExtraDeviceName(const std::string& snapshot_name) {
return snapshot_name + "-inner";
}
bool SnapshotManager::BeginUpdate() {
bool needs_merge = false;
if (!TryCancelUpdate(&needs_merge)) {
return false;
}
if (needs_merge) {
LOG(INFO) << "Wait for merge (if any) before beginning a new update.";
auto state = ProcessUpdateState();
LOG(INFO) << "Merged with state = " << state;
}
auto file = LockExclusive();
if (!file) return false;
// Purge the ImageManager just in case there is a corrupt lp_metadata file
// lying around. (NB: no need to return false on an error, we can let the
// update try to progress.)
if (EnsureImageManager()) {
images_->RemoveAllImages();
}
auto state = ReadUpdateState(file.get());
if (state != UpdateState::None) {
LOG(ERROR) << "An update is already in progress, cannot begin a new update";
return false;
}
return WriteUpdateState(file.get(), UpdateState::Initiated);
}
bool SnapshotManager::CancelUpdate() {
bool needs_merge = false;
if (!TryCancelUpdate(&needs_merge)) {
return false;
}
if (needs_merge) {
LOG(ERROR) << "Cannot cancel update after it has completed or started merging";
}
return !needs_merge;
}
bool SnapshotManager::TryCancelUpdate(bool* needs_merge) {
*needs_merge = false;
auto file = LockExclusive();
if (!file) return false;
UpdateState state = ReadUpdateState(file.get());
if (state == UpdateState::None) return true;
if (state == UpdateState::Initiated) {
LOG(INFO) << "Update has been initiated, now canceling";
return RemoveAllUpdateState(file.get());
}
if (state == UpdateState::Unverified) {
// We completed an update, but it can still be canceled if we haven't booted into it.
auto slot = GetCurrentSlot();
if (slot != Slot::Target) {
LOG(INFO) << "Canceling previously completed updates (if any)";
return RemoveAllUpdateState(file.get());
}
}
*needs_merge = true;
return true;
}
std::string SnapshotManager::ReadUpdateSourceSlotSuffix() {
auto boot_file = GetSnapshotBootIndicatorPath();
std::string contents;
if (!android::base::ReadFileToString(boot_file, &contents)) {
PLOG(WARNING) << "Cannot read " << boot_file;
return {};
}
return contents;
}
SnapshotManager::Slot SnapshotManager::GetCurrentSlot() {
auto contents = ReadUpdateSourceSlotSuffix();
if (contents.empty()) {
return Slot::Unknown;
}
if (device_->GetSlotSuffix() == contents) {
return Slot::Source;
}
return Slot::Target;
}
static bool RemoveFileIfExists(const std::string& path) {
std::string message;
if (!android::base::RemoveFileIfExists(path, &message)) {
LOG(ERROR) << "Remove failed: " << path << ": " << message;
return false;
}
return true;
}
bool SnapshotManager::RemoveAllUpdateState(LockedFile* lock, const std::function<bool()>& prolog) {
if (prolog && !prolog()) {
LOG(WARNING) << "Can't RemoveAllUpdateState: prolog failed.";
return false;
}
LOG(INFO) << "Removing all update state.";
if (!RemoveAllSnapshots(lock)) {
LOG(ERROR) << "Could not remove all snapshots";
return false;
}
// It's okay if these fail:
// - For SnapshotBoot and Rollback, 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.
// - For ForwardMerge, FinishedSnapshotWrites asserts that the existence of the indicator
// matches the incoming update.
std::vector<std::string> files = {
GetSnapshotBootIndicatorPath(),
GetRollbackIndicatorPath(),
GetForwardMergeIndicatorPath(),
};
for (const auto& file : files) {
RemoveFileIfExists(file);
}
// If this fails, we'll keep trying to remove the update state (as the
// device reboots or starts a new update) until it finally succeeds.
return WriteUpdateState(lock, UpdateState::None);
}
bool SnapshotManager::FinishedSnapshotWrites(bool wipe) {
auto lock = LockExclusive();
if (!lock) return false;
auto update_state = ReadUpdateState(lock.get());
if (update_state == UpdateState::Unverified) {
LOG(INFO) << "FinishedSnapshotWrites already called before. Ignored.";
return true;
}
if (update_state != UpdateState::Initiated) {
LOG(ERROR) << "Can only transition to the Unverified state from the Initiated state.";
return false;
}
if (!EnsureNoOverflowSnapshot(lock.get())) {
LOG(ERROR) << "Cannot ensure there are no overflow snapshots.";
return false;
}
if (!UpdateForwardMergeIndicator(wipe)) {
return false;
}
// This file is written on boot to detect whether a rollback occurred. It
// MUST NOT exist before rebooting, otherwise, we're at risk of deleting
// snapshots too early.
if (!RemoveFileIfExists(GetRollbackIndicatorPath())) {
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 (!WriteStringToFileAtomic(contents, boot_file)) {
PLOG(ERROR) << "write failed: " << boot_file;
return false;
}
return WriteUpdateState(lock.get(), UpdateState::Unverified);
}
bool SnapshotManager::CreateSnapshot(LockedFile* lock, SnapshotStatus* status) {
CHECK(lock);
CHECK(lock->lock_mode() == LOCK_EX);
CHECK(status);
if (status->name().empty()) {
LOG(ERROR) << "SnapshotStatus has no name.";
return false;
}
// Check these sizes. Like liblp, we guarantee the partition size is
// respected, which means it has to be sector-aligned. (This guarantee is
// useful for locating avb footers correctly). The COW file size, however,
// can be arbitrarily larger than specified, so we can safely round it up.
if (status->device_size() % kSectorSize != 0) {
LOG(ERROR) << "Snapshot " << status->name()
<< " device size is not a multiple of the sector size: "
<< status->device_size();
return false;
}
if (status->snapshot_size() % kSectorSize != 0) {
LOG(ERROR) << "Snapshot " << status->name()
<< " snapshot size is not a multiple of the sector size: "
<< status->snapshot_size();
return false;
}
if (status->cow_partition_size() % kSectorSize != 0) {
LOG(ERROR) << "Snapshot " << status->name()
<< " cow partition size is not a multiple of the sector size: "
<< status->cow_partition_size();
return false;
}
if (status->cow_file_size() % kSectorSize != 0) {
LOG(ERROR) << "Snapshot " << status->name()
<< " cow file size is not a multiple of the sector size: "
<< status->cow_file_size();
return false;
}
status->set_state(SnapshotState::CREATED);
status->set_sectors_allocated(0);
status->set_metadata_sectors(0);
status->set_compression_enabled(IsCompressionEnabled());
if (!WriteSnapshotStatus(lock, *status)) {
PLOG(ERROR) << "Could not write snapshot status: " << status->name();
return false;
}
return true;
}
Return SnapshotManager::CreateCowImage(LockedFile* lock, const std::string& name) {
CHECK(lock);
CHECK(lock->lock_mode() == LOCK_EX);
if (!EnsureImageManager()) return Return::Error();
SnapshotStatus status;
if (!ReadSnapshotStatus(lock, name, &status)) {
return Return::Error();
}
// The COW file size should have been rounded up to the nearest sector in CreateSnapshot.
if (status.cow_file_size() % kSectorSize != 0) {
LOG(ERROR) << "Snapshot " << name << " COW file size is not a multiple of the sector size: "
<< status.cow_file_size();
return Return::Error();
}
std::string cow_image_name = GetCowImageDeviceName(name);
int cow_flags = IImageManager::CREATE_IMAGE_DEFAULT;
return Return(images_->CreateBackingImage(cow_image_name, status.cow_file_size(), cow_flags));
}
bool SnapshotManager::MapDmUserCow(LockedFile* lock, const std::string& name,
const std::string& cow_file, const std::string& base_device,
const std::chrono::milliseconds& timeout_ms, std::string* path) {
CHECK(lock);
auto& dm = DeviceMapper::Instance();
// Use an extra decoration for first-stage init, so we can transition
// to a new table entry in second-stage.
std::string misc_name = name;
if (use_first_stage_snapuserd_) {
misc_name += "-init";
}
if (!EnsureSnapuserdConnected()) {
return false;
}
uint64_t base_sectors = snapuserd_client_->InitDmUserCow(misc_name, cow_file, base_device);
if (base_sectors == 0) {
LOG(ERROR) << "Failed to retrieve base_sectors from Snapuserd";
return false;
}
DmTable table;
table.Emplace<DmTargetUser>(0, base_sectors, misc_name);
if (!dm.CreateDevice(name, table, path, timeout_ms)) {
return false;
}
if (!WaitForDevice(*path, timeout_ms)) {
return false;
}
auto control_device = "/dev/dm-user/" + misc_name;
if (!WaitForDevice(control_device, timeout_ms)) {
return false;
}
return snapuserd_client_->AttachDmUser(misc_name);
}
bool SnapshotManager::MapSnapshot(LockedFile* lock, const std::string& name,
const std::string& base_device, const std::string& cow_device,
const std::chrono::milliseconds& timeout_ms,
std::string* dev_path) {
CHECK(lock);
SnapshotStatus status;
if (!ReadSnapshotStatus(lock, name, &status)) {
return false;
}
if (status.state() == SnapshotState::NONE || status.state() == SnapshotState::MERGE_COMPLETED) {
LOG(ERROR) << "Should not create a snapshot device for " << name
<< " after merging has completed.";
return false;
}
// Validate the block device size, as well as the requested snapshot size.
// Note that during first-stage init, we don't have the device paths.
if (android::base::StartsWith(base_device, "/")) {
unique_fd fd(open(base_device.c_str(), O_RDONLY | O_CLOEXEC));
if (fd < 0) {
PLOG(ERROR) << "open failed: " << base_device;
return false;
}
auto dev_size = get_block_device_size(fd);
if (!dev_size) {
PLOG(ERROR) << "Could not determine block device size: " << base_device;
return false;
}
if (status.device_size() != dev_size) {
LOG(ERROR) << "Block device size for " << base_device << " does not match"
<< "(expected " << status.device_size() << ", got " << dev_size << ")";
return false;
}
}
if (status.device_size() % kSectorSize != 0) {
LOG(ERROR) << "invalid blockdev size for " << base_device << ": " << status.device_size();
return false;
}
if (status.snapshot_size() % kSectorSize != 0 ||
status.snapshot_size() > status.device_size()) {
LOG(ERROR) << "Invalid snapshot size for " << base_device << ": " << status.snapshot_size();
return false;
}
uint64_t snapshot_sectors = status.snapshot_size() / kSectorSize;
uint64_t linear_sectors = (status.device_size() - status.snapshot_size()) / kSectorSize;
auto& dm = DeviceMapper::Instance();
// Note that merging is a global state. We do track whether individual devices
// have completed merging, but the start of the merge process is considered
// atomic.
SnapshotStorageMode mode;
switch (ReadUpdateState(lock)) {
case UpdateState::MergeCompleted:
case UpdateState::MergeNeedsReboot:
LOG(ERROR) << "Should not create a snapshot device for " << name
<< " after global merging has completed.";
return false;
case UpdateState::Merging:
case UpdateState::MergeFailed:
// Note: MergeFailed indicates that a merge is in progress, but
// is possibly stalled. We still have to honor the merge.
mode = SnapshotStorageMode::Merge;
break;
default:
mode = SnapshotStorageMode::Persistent;
break;
}
// The kernel (tested on 4.19) crashes horribly if a device has both a snapshot
// and a linear target in the same table. Instead, we stack them, and give the
// snapshot device a different name. It is not exposed to the caller in this
// case.
auto snap_name = (linear_sectors > 0) ? GetSnapshotExtraDeviceName(name) : name;
DmTable table;
table.Emplace<DmTargetSnapshot>(0, snapshot_sectors, base_device, cow_device, mode,
kSnapshotChunkSize);
if (!dm.CreateDevice(snap_name, table, dev_path, timeout_ms)) {
LOG(ERROR) << "Could not create snapshot device: " << snap_name;
return false;
}
if (linear_sectors) {
std::string snap_dev;
if (!dm.GetDeviceString(snap_name, &snap_dev)) {
LOG(ERROR) << "Cannot determine major/minor for: " << snap_name;
return false;
}
// Our stacking will looks like this:
// [linear, linear] ; to snapshot, and non-snapshot region of base device
// [snapshot-inner]
// [base device] [cow]
DmTable table;
table.Emplace<DmTargetLinear>(0, snapshot_sectors, snap_dev, 0);
table.Emplace<DmTargetLinear>(snapshot_sectors, linear_sectors, base_device,
snapshot_sectors);
if (!dm.CreateDevice(name, table, dev_path, timeout_ms)) {
LOG(ERROR) << "Could not create outer snapshot device: " << name;
dm.DeleteDevice(snap_name);
return false;
}
}
// :TODO: when merging is implemented, we need to add an argument to the
// status indicating how much progress is left to merge. (device-mapper
// does not retain the initial values, so we can't derive them.)
return true;
}
std::optional<std::string> SnapshotManager::MapCowImage(
const std::string& name, const std::chrono::milliseconds& timeout_ms) {
if (!EnsureImageManager()) return std::nullopt;
auto cow_image_name = GetCowImageDeviceName(name);
bool ok;
std::string cow_dev;
if (has_local_image_manager_) {
// If we forced a local image manager, it means we don't have binder,
// which means first-stage init. We must use device-mapper.
const auto& opener = device_->GetPartitionOpener();
ok = images_->MapImageWithDeviceMapper(opener, cow_image_name, &cow_dev);
} else {
ok = images_->MapImageDevice(cow_image_name, timeout_ms, &cow_dev);
}
if (ok) {
LOG(INFO) << "Mapped " << cow_image_name << " to " << cow_dev;
return cow_dev;
}
LOG(ERROR) << "Could not map image device: " << cow_image_name;
return std::nullopt;
}
bool SnapshotManager::UnmapSnapshot(LockedFile* lock, const std::string& name) {
CHECK(lock);
auto& dm = DeviceMapper::Instance();
if (!dm.DeleteDeviceIfExists(name)) {
LOG(ERROR) << "Could not delete snapshot device: " << name;
return false;
}
auto snapshot_extra_device = GetSnapshotExtraDeviceName(name);
if (!dm.DeleteDeviceIfExists(snapshot_extra_device)) {
LOG(ERROR) << "Could not delete snapshot inner device: " << snapshot_extra_device;
return false;
}
return true;
}
bool SnapshotManager::UnmapCowImage(const std::string& name) {
if (!EnsureImageManager()) return false;
return images_->UnmapImageIfExists(GetCowImageDeviceName(name));
}
bool SnapshotManager::DeleteSnapshot(LockedFile* lock, const std::string& name) {
CHECK(lock);
CHECK(lock->lock_mode() == LOCK_EX);
if (!EnsureImageManager()) return false;
if (!UnmapCowDevices(lock, name)) {
return false;
}
// We can't delete snapshots in recovery. The only way we'd try is it we're
// completing or canceling a merge in preparation for a data wipe, in which
// case, we don't care if the file sticks around.
if (device_->IsRecovery()) {
LOG(INFO) << "Skipping delete of snapshot " << name << " in recovery.";
return true;
}
auto cow_image_name = GetCowImageDeviceName(name);
if (images_->BackingImageExists(cow_image_name)) {
if (!images_->DeleteBackingImage(cow_image_name)) {
return false;
}
}
std::string error;
auto file_path = GetSnapshotStatusFilePath(name);
if (!android::base::RemoveFileIfExists(file_path, &error)) {
LOG(ERROR) << "Failed to remove status file " << file_path << ": " << error;
return false;
}
return true;
}
bool SnapshotManager::InitiateMerge(uint64_t* cow_file_size) {
auto lock = LockExclusive();
if (!lock) return false;
UpdateState state = ReadUpdateState(lock.get());
if (state != UpdateState::Unverified) {
LOG(ERROR) << "Cannot begin a merge if an update has not been verified";
return false;
}
auto slot = GetCurrentSlot();
if (slot != Slot::Target) {
LOG(ERROR) << "Device cannot merge while not booting from new slot";
return false;
}
std::vector<std::string> snapshots;
if (!ListSnapshots(lock.get(), &snapshots)) {
LOG(ERROR) << "Could not list snapshots";
return false;
}
auto other_suffix = device_->GetOtherSlotSuffix();
auto& dm = DeviceMapper::Instance();
for (const auto& snapshot : snapshots) {
if (android::base::EndsWith(snapshot, other_suffix)) {
// Allow the merge to continue, but log this unexpected case.
LOG(ERROR) << "Unexpected snapshot found during merge: " << snapshot;
continue;
}
// The device has to be mapped, since everything should be merged at
// the same time. This is a fairly serious error. We could forcefully
// map everything here, but it should have been mapped during first-
// stage init.
if (dm.GetState(snapshot) == DmDeviceState::INVALID) {
LOG(ERROR) << "Cannot begin merge; device " << snapshot << " is not mapped.";
return false;
}
}
auto metadata = ReadCurrentMetadata();
for (auto it = snapshots.begin(); it != snapshots.end();) {
switch (GetMetadataPartitionState(*metadata, *it)) {
case MetadataPartitionState::Flashed:
LOG(WARNING) << "Detected re-flashing for partition " << *it
<< ". Skip merging it.";
[[fallthrough]];
case MetadataPartitionState::None: {
LOG(WARNING) << "Deleting snapshot for partition " << *it;
if (!DeleteSnapshot(lock.get(), *it)) {
LOG(WARNING) << "Cannot delete snapshot for partition " << *it
<< ". Skip merging it anyways.";
}
it = snapshots.erase(it);
} break;
case MetadataPartitionState::Updated: {
++it;
} break;
}
}
uint64_t total_cow_file_size = 0;
DmTargetSnapshot::Status initial_target_values = {};
for (const auto& snapshot : snapshots) {
DmTargetSnapshot::Status current_status;
if (!QuerySnapshotStatus(snapshot, nullptr, &current_status)) {
return false;
}
initial_target_values.sectors_allocated += current_status.sectors_allocated;
initial_target_values.total_sectors += current_status.total_sectors;
initial_target_values.metadata_sectors += current_status.metadata_sectors;
SnapshotStatus snapshot_status;
if (!ReadSnapshotStatus(lock.get(), snapshot, &snapshot_status)) {
return false;
}
total_cow_file_size += snapshot_status.cow_file_size();
}
if (cow_file_size) {
*cow_file_size = total_cow_file_size;
}
SnapshotUpdateStatus initial_status;
initial_status.set_state(UpdateState::Merging);
initial_status.set_sectors_allocated(initial_target_values.sectors_allocated);
initial_status.set_total_sectors(initial_target_values.total_sectors);
initial_status.set_metadata_sectors(initial_target_values.metadata_sectors);
// Point of no return - mark that we're starting a merge. From now on every
// snapshot must be a merge target.
if (!WriteSnapshotUpdateStatus(lock.get(), initial_status)) {
return false;
}
bool rewrote_all = true;
for (const auto& snapshot : snapshots) {
// If this fails, we have no choice but to continue. Everything must
// be merged. This is not an ideal state to be in, but it is safe,
// because we the next boot will try again.
if (!SwitchSnapshotToMerge(lock.get(), snapshot)) {
LOG(ERROR) << "Failed to switch snapshot to a merge target: " << snapshot;
rewrote_all = false;
}
}
// If we couldn't switch everything to a merge target, pre-emptively mark
// this merge as failed. It will get acknowledged when WaitForMerge() is
// called.
if (!rewrote_all) {
WriteUpdateState(lock.get(), UpdateState::MergeFailed);
}
// Return true no matter what, because a merge was initiated.
return true;
}
bool SnapshotManager::SwitchSnapshotToMerge(LockedFile* lock, const std::string& name) {
SnapshotStatus status;
if (!ReadSnapshotStatus(lock, name, &status)) {
return false;
}
if (status.state() != SnapshotState::CREATED) {
LOG(WARNING) << "Snapshot " << name
<< " has unexpected state: " << SnapshotState_Name(status.state());
}
// After this, we return true because we technically did switch to a merge
// target. Everything else we do here is just informational.
auto dm_name = GetSnapshotDeviceName(name, status);
if (!RewriteSnapshotDeviceTable(dm_name)) {
return false;
}
status.set_state(SnapshotState::MERGING);
DmTargetSnapshot::Status dm_status;
if (!QuerySnapshotStatus(dm_name, nullptr, &dm_status)) {
LOG(ERROR) << "Could not query merge status for snapshot: " << dm_name;
}
status.set_sectors_allocated(dm_status.sectors_allocated);
status.set_metadata_sectors(dm_status.metadata_sectors);
if (!WriteSnapshotStatus(lock, status)) {
LOG(ERROR) << "Could not update status file for snapshot: " << name;
}
return true;
}
bool SnapshotManager::RewriteSnapshotDeviceTable(const std::string& dm_name) {
auto& dm = DeviceMapper::Instance();
std::vector<DeviceMapper::TargetInfo> old_targets;
if (!dm.GetTableInfo(dm_name, &old_targets)) {
LOG(ERROR) << "Could not read snapshot device table: " << dm_name;
return false;
}
if (old_targets.size() != 1 || DeviceMapper::GetTargetType(old_targets[0].spec) != "snapshot") {
LOG(ERROR) << "Unexpected device-mapper table for snapshot: " << dm_name;
return false;
}
std::string base_device, cow_device;
if (!DmTargetSnapshot::GetDevicesFromParams(old_targets[0].data, &base_device, &cow_device)) {
LOG(ERROR) << "Could not derive underlying devices for snapshot: " << dm_name;
return false;
}
DmTable table;
table.Emplace<DmTargetSnapshot>(0, old_targets[0].spec.length, base_device, cow_device,
SnapshotStorageMode::Merge, kSnapshotChunkSize);
if (!dm.LoadTableAndActivate(dm_name, table)) {
LOG(ERROR) << "Could not swap device-mapper tables on snapshot device " << dm_name;
return false;
}
LOG(INFO) << "Successfully switched snapshot device to a merge target: " << dm_name;
return true;
}
enum class TableQuery {
Table,
Status,
};
static bool GetSingleTarget(const std::string& dm_name, TableQuery query,
DeviceMapper::TargetInfo* target) {
auto& dm = DeviceMapper::Instance();
if (dm.GetState(dm_name) == DmDeviceState::INVALID) {
return false;
}
std::vector<DeviceMapper::TargetInfo> targets;
bool result;
if (query == TableQuery::Status) {
result = dm.GetTableStatus(dm_name, &targets);
} else {
result = dm.GetTableInfo(dm_name, &targets);
}
if (!result) {
LOG(ERROR) << "Could not query device: " << dm_name;
return false;
}
if (targets.size() != 1) {
return false;
}
*target = std::move(targets[0]);
return true;
}
bool SnapshotManager::IsSnapshotDevice(const std::string& dm_name, TargetInfo* target) {
DeviceMapper::TargetInfo snap_target;
if (!GetSingleTarget(dm_name, TableQuery::Status, &snap_target)) {
return false;
}
auto type = DeviceMapper::GetTargetType(snap_target.spec);
if (type != "snapshot" && type != "snapshot-merge") {
return false;
}
if (target) {
*target = std::move(snap_target);
}
return true;
}
bool SnapshotManager::QuerySnapshotStatus(const std::string& dm_name, std::string* target_type,
DmTargetSnapshot::Status* status) {
DeviceMapper::TargetInfo target;
if (!IsSnapshotDevice(dm_name, &target)) {
LOG(ERROR) << "Device " << dm_name << " is not a snapshot or snapshot-merge device";
return false;
}
if (!DmTargetSnapshot::ParseStatusText(target.data, status)) {
LOG(ERROR) << "Could not parse snapshot status text: " << dm_name;
return false;
}
if (target_type) {
*target_type = DeviceMapper::GetTargetType(target.spec);
}
return true;
}
// Note that when a merge fails, we will *always* try again to complete the
// merge each time the device boots. There is no harm in doing so, and if
// the problem was transient, we might manage to get a new outcome.
UpdateState SnapshotManager::ProcessUpdateState(const std::function<bool()>& callback,
const std::function<bool()>& before_cancel) {
while (true) {
UpdateState state = CheckMergeState(before_cancel);
if (state == UpdateState::MergeFailed) {
AcknowledgeMergeFailure();
}
if (state != UpdateState::Merging) {
// Either there is no merge, or the merge was finished, so no need
// to keep waiting.
return state;
}
if (callback && !callback()) {
return state;
}
// This wait is not super time sensitive, so we have a relatively
// low polling frequency.
std::this_thread::sleep_for(kUpdateStateCheckInterval);
}
}
UpdateState SnapshotManager::CheckMergeState(const std::function<bool()>& before_cancel) {
auto lock = LockExclusive();
if (!lock) {
return UpdateState::MergeFailed;
}
UpdateState state = CheckMergeState(lock.get(), before_cancel);
if (state == UpdateState::MergeCompleted) {
// Do this inside the same lock. Failures get acknowledged without the
// lock, because flock() might have failed.
AcknowledgeMergeSuccess(lock.get());
} else if (state == UpdateState::Cancelled) {
if (!RemoveAllUpdateState(lock.get(), before_cancel)) {
return ReadSnapshotUpdateStatus(lock.get()).state();
}
}
return state;
}
UpdateState SnapshotManager::CheckMergeState(LockedFile* lock,
const std::function<bool()>& before_cancel) {
UpdateState state = ReadUpdateState(lock);
switch (state) {
case UpdateState::None:
case UpdateState::MergeCompleted:
// Harmless races are allowed between two callers of WaitForMerge,
// so in both of these cases we just propagate the state.
return state;
case UpdateState::Merging:
case UpdateState::MergeNeedsReboot:
case UpdateState::MergeFailed:
// We'll poll each snapshot below. Note that for the NeedsReboot
// case, we always poll once to give cleanup another opportunity to
// run.
break;
case UpdateState::Unverified:
// This is an edge case. Normally cancelled updates are detected
// via the merge poll below, but if we never started a merge, we
// need to also check here.
if (HandleCancelledUpdate(lock, before_cancel)) {
return UpdateState::Cancelled;
}
return state;
default:
return state;
}
std::vector<std::string> snapshots;
if (!ListSnapshots(lock, &snapshots)) {
return UpdateState::MergeFailed;
}
bool cancelled = false;
bool failed = false;
bool merging = false;
bool needs_reboot = false;
for (const auto& snapshot : snapshots) {
UpdateState snapshot_state = CheckTargetMergeState(lock, snapshot);
switch (snapshot_state) {
case UpdateState::MergeFailed:
failed = true;
break;
case UpdateState::Merging:
merging = true;
break;
case UpdateState::MergeNeedsReboot:
needs_reboot = true;
break;
case UpdateState::MergeCompleted:
break;
case UpdateState::Cancelled:
cancelled = true;
break;
default:
LOG(ERROR) << "Unknown merge status for \"" << snapshot << "\": "
<< "\"" << snapshot_state << "\"";
failed = true;
break;
}
}
if (merging) {
// Note that we handle "Merging" before we handle anything else. We
// want to poll until *nothing* is merging if we can, so everything has
// a chance to get marked as completed or failed.
return UpdateState::Merging;
}
if (failed) {
// Note: since there are many drop-out cases for failure, we acknowledge
// it in WaitForMerge rather than here and elsewhere.
return UpdateState::MergeFailed;
}
if (needs_reboot) {
WriteUpdateState(lock, UpdateState::MergeNeedsReboot);
return UpdateState::MergeNeedsReboot;
}
if (cancelled) {
// This is an edge case, that we handle as correctly as we sensibly can.
// The underlying partition has changed behind update_engine, and we've
// removed the snapshot as a result. The exact state of the update is
// undefined now, but this can only happen on an unlocked device where
// partitions can be flashed without wiping userdata.
return UpdateState::Cancelled;
}
return UpdateState::MergeCompleted;
}
UpdateState SnapshotManager::CheckTargetMergeState(LockedFile* lock, const std::string& name) {
SnapshotStatus snapshot_status;
if (!ReadSnapshotStatus(lock, name, &snapshot_status)) {
return UpdateState::MergeFailed;
}
std::string dm_name = GetSnapshotDeviceName(name, snapshot_status);
std::unique_ptr<LpMetadata> current_metadata;
if (!IsSnapshotDevice(dm_name)) {
if (!current_metadata) {
current_metadata = ReadCurrentMetadata();
}
if (!current_metadata ||
GetMetadataPartitionState(*current_metadata, name) != MetadataPartitionState::Updated) {
DeleteSnapshot(lock, name);
return UpdateState::Cancelled;
}
// During a check, we decided the merge was complete, but we were unable to
// collapse the device-mapper stack and perform COW cleanup. If we haven't
// rebooted after this check, the device will still be a snapshot-merge
// target. If the have rebooted, the device will now be a linear target,
// and we can try cleanup again.
if (snapshot_status.state() == SnapshotState::MERGE_COMPLETED) {
// NB: It's okay if this fails now, we gave cleanup our best effort.
OnSnapshotMergeComplete(lock, name, snapshot_status);
return UpdateState::MergeCompleted;
}
LOG(ERROR) << "Expected snapshot or snapshot-merge for device: " << dm_name;
return UpdateState::MergeFailed;
}
// This check is expensive so it is only enabled for debugging.
DCHECK((current_metadata = ReadCurrentMetadata()) &&
GetMetadataPartitionState(*current_metadata, name) == MetadataPartitionState::Updated);
std::string target_type;
DmTargetSnapshot::Status status;
if (!QuerySnapshotStatus(dm_name, &target_type, &status)) {
return UpdateState::MergeFailed;
}
if (target_type != "snapshot-merge") {
// We can get here if we failed to rewrite the target type in
// InitiateMerge(). If we failed to create the target in first-stage
// init, boot would not succeed.
LOG(ERROR) << "Snapshot " << name << " has incorrect target type: " << target_type;
return UpdateState::MergeFailed;
}
// These two values are equal when merging is complete.
if (status.sectors_allocated != status.metadata_sectors) {
if (snapshot_status.state() == SnapshotState::MERGE_COMPLETED) {
LOG(ERROR) << "Snapshot " << name << " is merging after being marked merge-complete.";
return UpdateState::MergeFailed;
}
return UpdateState::Merging;
}
// Merging is done. First, update the status file to indicate the merge
// is complete. We do this before calling OnSnapshotMergeComplete, even
// though this means the write is potentially wasted work (since in the
// ideal case we'll immediately delete the file).
//
// This makes it simpler to reason about the next reboot: no matter what
// part of cleanup failed, first-stage init won't try to create another
// snapshot device for this partition.
snapshot_status.set_state(SnapshotState::MERGE_COMPLETED);
if (!WriteSnapshotStatus(lock, snapshot_status)) {
return UpdateState::MergeFailed;
}
if (!OnSnapshotMergeComplete(lock, name, snapshot_status)) {
return UpdateState::MergeNeedsReboot;
}
return UpdateState::MergeCompleted;
}
std::string SnapshotManager::GetSnapshotBootIndicatorPath() {
return metadata_dir_ + "/" + android::base::Basename(kBootIndicatorPath);
}
std::string SnapshotManager::GetRollbackIndicatorPath() {
return metadata_dir_ + "/" + android::base::Basename(kRollbackIndicatorPath);
}
std::string SnapshotManager::GetForwardMergeIndicatorPath() {
return metadata_dir_ + "/allow-forward-merge";
}
void SnapshotManager::AcknowledgeMergeSuccess(LockedFile* lock) {
// It's not possible to remove update state in recovery, so write an
// indicator that cleanup is needed on reboot. If a factory data reset
// was requested, it doesn't matter, everything will get wiped anyway.
// To make testing easier we consider a /data wipe as cleaned up.
if (device_->IsRecovery() && !in_factory_data_reset_) {
WriteUpdateState(lock, UpdateState::MergeCompleted);
return;
}
RemoveAllUpdateState(lock);
}
void SnapshotManager::AcknowledgeMergeFailure() {
// Log first, so worst case, we always have a record of why the calls below
// were being made.
LOG(ERROR) << "Merge could not be completed and will be marked as failed.";
auto lock = LockExclusive();
if (!lock) return;
// Since we released the lock in between WaitForMerge and here, it's
// possible (1) the merge successfully completed or (2) was already
// marked as a failure. So make sure to check the state again, and
// only mark as a failure if appropriate.
UpdateState state = ReadUpdateState(lock.get());
if (state != UpdateState::Merging && state != UpdateState::MergeNeedsReboot) {
return;
}
WriteUpdateState(lock.get(), UpdateState::MergeFailed);
}
bool SnapshotManager::OnSnapshotMergeComplete(LockedFile* lock, const std::string& name,
const SnapshotStatus& status) {
auto dm_name = GetSnapshotDeviceName(name, status);
if (IsSnapshotDevice(dm_name)) {
// We are extra-cautious here, to avoid deleting the wrong table.
std::string target_type;
DmTargetSnapshot::Status dm_status;
if (!QuerySnapshotStatus(dm_name, &target_type, &dm_status)) {
return false;
}
if (target_type != "snapshot-merge") {
LOG(ERROR) << "Unexpected target type " << target_type
<< " for snapshot device: " << dm_name;
return false;
}
if (dm_status.sectors_allocated != dm_status.metadata_sectors) {
LOG(ERROR) << "Merge is unexpectedly incomplete for device " << dm_name;
return false;
}
if (!CollapseSnapshotDevice(name, status)) {
LOG(ERROR) << "Unable to collapse snapshot: " << name;
return false;
}
// Note that collapsing is implicitly an Unmap, so we don't need to
// unmap the snapshot.
}
if (!DeleteSnapshot(lock, name)) {
LOG(ERROR) << "Could not delete snapshot: " << name;
return false;
}
return true;
}
bool SnapshotManager::CollapseSnapshotDevice(const std::string& name,
const SnapshotStatus& status) {
auto& dm = DeviceMapper::Instance();
auto dm_name = GetSnapshotDeviceName(name, status);
// Verify we have a snapshot-merge device.
DeviceMapper::TargetInfo target;
if (!GetSingleTarget(dm_name, TableQuery::Table, &target)) {
return false;
}
if (DeviceMapper::GetTargetType(target.spec) != "snapshot-merge") {
// This should be impossible, it was checked earlier.
LOG(ERROR) << "Snapshot device has invalid target type: " << dm_name;
return false;
}
std::string base_device, cow_device;
if (!DmTargetSnapshot::GetDevicesFromParams(target.data, &base_device, &cow_device)) {
LOG(ERROR) << "Could not parse snapshot device " << dm_name
<< " parameters: " << target.data;
return false;
}
uint64_t snapshot_sectors = status.snapshot_size() / kSectorSize;
if (snapshot_sectors * kSectorSize != status.snapshot_size()) {
LOG(ERROR) << "Snapshot " << name
<< " size is not sector aligned: " << status.snapshot_size();
return false;
}
if (dm_name != name) {
// We've derived the base device, but we actually need to replace the
// table of the outermost device. Do a quick verification that this
// device looks like we expect it to.
std::vector<DeviceMapper::TargetInfo> outer_table;
if (!dm.GetTableInfo(name, &outer_table)) {
LOG(ERROR) << "Could not validate outer snapshot table: " << name;
return false;
}
if (outer_table.size() != 2) {
LOG(ERROR) << "Expected 2 dm-linear targets for table " << name
<< ", got: " << outer_table.size();
return false;
}
for (const auto& target : outer_table) {
auto target_type = DeviceMapper::GetTargetType(target.spec);
if (target_type != "linear") {
LOG(ERROR) << "Outer snapshot table may only contain linear targets, but " << name
<< " has target: " << target_type;
return false;
}
}
if (outer_table[0].spec.length != snapshot_sectors) {
LOG(ERROR) << "dm-snapshot " << name << " should have " << snapshot_sectors
<< " sectors, got: " << outer_table[0].spec.length;
return false;
}
uint64_t expected_device_sectors = status.device_size() / kSectorSize;
uint64_t actual_device_sectors = outer_table[0].spec.length + outer_table[1].spec.length;
if (expected_device_sectors != actual_device_sectors) {
LOG(ERROR) << "Outer device " << name << " should have " << expected_device_sectors
<< " sectors, got: " << actual_device_sectors;
return false;
}
}
uint32_t slot = SlotNumberForSlotSuffix(device_->GetSlotSuffix());
// Create a DmTable that is identical to the base device.
CreateLogicalPartitionParams base_device_params{
.block_device = device_->GetSuperDevice(slot),
.metadata_slot = slot,
.partition_name = name,
.partition_opener = &device_->GetPartitionOpener(),
};
DmTable table;
if (!CreateDmTable(base_device_params, &table)) {
LOG(ERROR) << "Could not create a DmTable for partition: " << name;
return false;
}
// Note: we are replacing the *outer* table here, so we do not use dm_name.
if (!dm.LoadTableAndActivate(name, table)) {
return false;
}
// Attempt to delete the snapshot device if one still exists. Nothing
// should be depending on the device, and device-mapper should have
// flushed remaining I/O. We could in theory replace with dm-zero (or
// re-use the table above), but for now it's better to know why this
// would fail.
if (dm_name != name && !dm.DeleteDeviceIfExists(dm_name)) {
LOG(ERROR) << "Unable to delete snapshot device " << dm_name << ", COW cannot be "
<< "reclaimed until after reboot.";
return false;
}
if (status.compression_enabled()) {
UnmapDmUserDevice(name);
}
// Cleanup the base device as well, since it is no longer used. This does
// not block cleanup.
auto base_name = GetBaseDeviceName(name);
if (!dm.DeleteDeviceIfExists(base_name)) {
LOG(ERROR) << "Unable to delete base device for snapshot: " << base_name;
}
return true;
}
bool SnapshotManager::HandleCancelledUpdate(LockedFile* lock,
const std::function<bool()>& before_cancel) {
auto slot = GetCurrentSlot();
if (slot == Slot::Unknown) {
return false;
}
// If all snapshots were reflashed, then cancel the entire update.
if (AreAllSnapshotsCancelled(lock)) {
LOG(WARNING) << "Detected re-flashing, cancelling unverified update.";
return RemoveAllUpdateState(lock, before_cancel);
}
// If update has been rolled back, then cancel the entire update.
// Client (update_engine) is responsible for doing additional cleanup work on its own states
// when ProcessUpdateState() returns UpdateState::Cancelled.
auto current_slot = GetCurrentSlot();
if (current_slot != Slot::Source) {
LOG(INFO) << "Update state is being processed while booting at " << current_slot
<< " slot, taking no action.";
return false;
}
// current_slot == Source. Attempt to detect rollbacks.
if (access(GetRollbackIndicatorPath().c_str(), F_OK) != 0) {
// This unverified update is not attempted. Take no action.
PLOG(INFO) << "Rollback indicator not detected. "
<< "Update state is being processed before reboot, taking no action.";
return false;
}
LOG(WARNING) << "Detected rollback, cancelling unverified update.";
return RemoveAllUpdateState(lock, before_cancel);
}
bool SnapshotManager::PerformInitTransition(InitTransition transition,
std::vector<std::string>* snapuserd_argv) {
LOG(INFO) << "Performing transition for snapuserd.";
// Don't use EnsuerSnapuserdConnected() because this is called from init,
// and attempting to do so will deadlock.
if (!snapuserd_client_ && transition != InitTransition::SELINUX_DETACH) {
snapuserd_client_ = SnapuserdClient::Connect(kSnapuserdSocket, 10s);
if (!snapuserd_client_) {
LOG(ERROR) << "Unable to connect to snapuserd";
return false;
}
}
auto& dm = DeviceMapper::Instance();
auto lock = LockExclusive();
if (!lock) return false;
std::vector<std::string> snapshots;
if (!ListSnapshots(lock.get(), &snapshots)) {
LOG(ERROR) << "Failed to list snapshots.";
return false;
}
size_t num_cows = 0;
size_t ok_cows = 0;
for (const auto& snapshot : snapshots) {
std::string user_cow_name = GetDmUserCowName(snapshot);
if (dm.GetState(user_cow_name) == DmDeviceState::INVALID) {
continue;
}
DeviceMapper::TargetInfo target;
if (!GetSingleTarget(user_cow_name, TableQuery::Table, &target)) {
continue;
}
auto target_type = DeviceMapper::GetTargetType(target.spec);
if (target_type != "user") {
LOG(ERROR) << "Unexpected target type for " << user_cow_name << ": " << target_type;
continue;
}
num_cows++;
SnapshotStatus snapshot_status;
if (!ReadSnapshotStatus(lock.get(), snapshot, &snapshot_status)) {
LOG(ERROR) << "Unable to read snapshot status: " << snapshot;
continue;
}
auto misc_name = user_cow_name;
if (transition == InitTransition::SELINUX_DETACH) {
misc_name += "-selinux";
}
DmTable table;
table.Emplace<DmTargetUser>(0, target.spec.length, misc_name);
if (!dm.LoadTableAndActivate(user_cow_name, table)) {
LOG(ERROR) << "Unable to swap tables for " << misc_name;
continue;
}
std::string backing_device;
if (!dm.GetDmDevicePathByName(GetBaseDeviceName(snapshot), &backing_device)) {
LOG(ERROR) << "Could not get device path for " << GetBaseDeviceName(snapshot);
continue;
}
// If no partition was created (the COW exists entirely on /data), the
// device-mapper layering is different than if we had a partition.
std::string cow_image_name;
if (snapshot_status.cow_partition_size() == 0) {
cow_image_name = GetCowImageDeviceName(snapshot);
} else {
cow_image_name = GetCowName(snapshot);
}
std::string cow_image_device;
if (!dm.GetDmDevicePathByName(cow_image_name, &cow_image_device)) {
LOG(ERROR) << "Could not get device path for " << cow_image_name;
continue;
}
// Wait for ueventd to acknowledge and create the control device node.
std::string control_device = "/dev/dm-user/" + misc_name;
if (!WaitForDevice(control_device, 10s)) {
continue;
}
if (transition == InitTransition::SELINUX_DETACH) {
auto message = misc_name + "," + cow_image_device + "," + backing_device;
snapuserd_argv->emplace_back(std::move(message));
// Do not attempt to connect to the new snapuserd yet, it hasn't
// been started. We do however want to wait for the misc device
// to have been created.
ok_cows++;
continue;
}
uint64_t base_sectors =
snapuserd_client_->InitDmUserCow(misc_name, cow_image_device, backing_device);
if (base_sectors == 0) {
// Unrecoverable as metadata reads from cow device failed
LOG(FATAL) << "Failed to retrieve base_sectors from Snapuserd";
return false;
}
CHECK(base_sectors == target.spec.length);
if (!snapuserd_client_->AttachDmUser(misc_name)) {
// This error is unrecoverable. We cannot proceed because reads to
// the underlying device will fail.
LOG(FATAL) << "Could not initialize snapuserd for " << user_cow_name;
return false;
}
ok_cows++;
}
if (ok_cows != num_cows) {
LOG(ERROR) << "Could not transition all snapuserd consumers.";
return false;
}
return true;
}
std::unique_ptr<LpMetadata> SnapshotManager::ReadCurrentMetadata() {
const auto& opener = device_->GetPartitionOpener();
uint32_t slot = SlotNumberForSlotSuffix(device_->GetSlotSuffix());
auto super_device = device_->GetSuperDevice(slot);
auto metadata = android::fs_mgr::ReadMetadata(opener, super_device, slot);
if (!metadata) {
LOG(ERROR) << "Could not read dynamic partition metadata for device: " << super_device;
return nullptr;
}
return metadata;
}
SnapshotManager::MetadataPartitionState SnapshotManager::GetMetadataPartitionState(
const LpMetadata& metadata, const std::string& name) {
auto partition = android::fs_mgr::FindPartition(metadata, name);
if (!partition) return MetadataPartitionState::None;
if (partition->attributes & LP_PARTITION_ATTR_UPDATED) {
return MetadataPartitionState::Updated;
}
return MetadataPartitionState::Flashed;
}
bool SnapshotManager::AreAllSnapshotsCancelled(LockedFile* lock) {
std::vector<std::string> snapshots;
if (!ListSnapshots(lock, &snapshots)) {
LOG(WARNING) << "Failed to list snapshots to determine whether device has been flashed "
<< "after applying an update. Assuming no snapshots.";
// Let HandleCancelledUpdate resets UpdateState.
return true;
}
std::map<std::string, bool> flashing_status;
if (!GetSnapshotFlashingStatus(lock, snapshots, &flashing_status)) {
LOG(WARNING) << "Failed to determine whether partitions have been flashed. Not"
<< "removing update states.";
return false;
}
bool all_snapshots_cancelled = std::all_of(flashing_status.begin(), flashing_status.end(),
[](const auto& pair) { return pair.second; });
if (all_snapshots_cancelled) {
LOG(WARNING) << "All partitions are re-flashed after update, removing all update states.";
}
return all_snapshots_cancelled;
}
bool SnapshotManager::GetSnapshotFlashingStatus(LockedFile* lock,
const std::vector<std::string>& snapshots,
std::map<std::string, bool>* out) {
CHECK(lock);
auto source_slot_suffix = ReadUpdateSourceSlotSuffix();
if (source_slot_suffix.empty()) {
return false;
}
uint32_t source_slot = SlotNumberForSlotSuffix(source_slot_suffix);
uint32_t target_slot = (source_slot == 0) ? 1 : 0;
// Attempt to detect re-flashing on each partition.
// - If all partitions are re-flashed, we can proceed to cancel the whole update.
// - If only some of the partitions are re-flashed, snapshots for re-flashed partitions are
// deleted. Caller is responsible for merging the rest of the snapshots.
// - If none of the partitions are re-flashed, caller is responsible for merging the snapshots.
//
// Note that we use target slot metadata, since if an OTA has been applied
// to the target slot, we can detect the UPDATED flag. Any kind of flash
// operation against dynamic partitions ensures that all copies of the
// metadata are in sync, so flashing all partitions on the source slot will
// remove the UPDATED flag on the target slot as well.
const auto& opener = device_->GetPartitionOpener();
auto super_device = device_->GetSuperDevice(target_slot);
auto metadata = android::fs_mgr::ReadMetadata(opener, super_device, target_slot);
if (!metadata) {
return false;
}
for (const auto& snapshot_name : snapshots) {
if (GetMetadataPartitionState(*metadata, snapshot_name) ==
MetadataPartitionState::Updated) {
out->emplace(snapshot_name, false);
} else {
// Delete snapshots for partitions that are re-flashed after the update.
LOG(WARNING) << "Detected re-flashing of partition " << snapshot_name << ".";
out->emplace(snapshot_name, true);
}
}
return true;
}
bool SnapshotManager::RemoveAllSnapshots(LockedFile* lock) {
std::vector<std::string> snapshots;
if (!ListSnapshots(lock, &snapshots)) {
LOG(ERROR) << "Could not list snapshots";
return false;
}
std::map<std::string, bool> flashing_status;
if (!GetSnapshotFlashingStatus(lock, snapshots, &flashing_status)) {
LOG(WARNING) << "Failed to get flashing status";
}
auto current_slot = GetCurrentSlot();
bool ok = true;
bool has_mapped_cow_images = false;
for (const auto& name : snapshots) {
// If booting off source slot, it is okay to unmap and delete all the snapshots.
// If boot indicator is missing, update state is None or Initiated, so
// it is also okay to unmap and delete all the snapshots.
// If booting off target slot,
// - should not unmap because:
// - In Android mode, snapshots are not mapped, but
// filesystems are mounting off dm-linear targets directly.
// - In recovery mode, assume nothing is mapped, so it is optional to unmap.
// - If partition is flashed or unknown, it is okay to delete snapshots.
// Otherwise (UPDATED flag), only delete snapshots if they are not mapped
// as dm-snapshot (for example, after merge completes).
bool should_unmap = current_slot != Slot::Target;
bool should_delete = ShouldDeleteSnapshot(lock, flashing_status, current_slot, name);
bool partition_ok = true;
if (should_unmap && !UnmapPartitionWithSnapshot(lock, name)) {
partition_ok = false;
}
if (partition_ok && should_delete && !DeleteSnapshot(lock, name)) {
partition_ok = false;
}
if (!partition_ok) {
// Remember whether or not we were able to unmap the cow image.
auto cow_image_device = GetCowImageDeviceName(name);
has_mapped_cow_images |=
(EnsureImageManager() && images_->IsImageMapped(cow_image_device));
ok = false;
}
}
if (ok || !has_mapped_cow_images) {
// Delete any image artifacts as a precaution, in case an update is
// being cancelled due to some corrupted state in an lp_metadata file.
// Note that we do not do this if some cow images are still mapped,
// since we must not remove backing storage if it's in use.
if (!EnsureImageManager() || !images_->RemoveAllImages()) {
LOG(ERROR) << "Could not remove all snapshot artifacts";
return false;
}
}
return ok;
}
// See comments in RemoveAllSnapshots().
bool SnapshotManager::ShouldDeleteSnapshot(LockedFile* lock,
const std::map<std::string, bool>& flashing_status,
Slot current_slot, const std::string& name) {
if (current_slot != Slot::Target) {
return true;
}
auto it = flashing_status.find(name);
if (it == flashing_status.end()) {
LOG(WARNING) << "Can't determine flashing status for " << name;
return true;
}
if (it->second) {
// partition flashed, okay to delete obsolete snapshots
return true;
}
// partition updated, only delete if not dm-snapshot
SnapshotStatus status;
if (!ReadSnapshotStatus(lock, name, &status)) {
LOG(WARNING) << "Unable to read snapshot status for " << name
<< ", guessing snapshot device name";
auto extra_name = GetSnapshotExtraDeviceName(name);
return !IsSnapshotDevice(name) && !IsSnapshotDevice(extra_name);
}
auto dm_name = GetSnapshotDeviceName(name, status);
return !IsSnapshotDevice(dm_name);
}
UpdateState SnapshotManager::GetUpdateState(double* progress) {
// If we've never started an update, the state file won't exist.
auto state_file = GetStateFilePath();
if (access(state_file.c_str(), F_OK) != 0 && errno == ENOENT) {
return UpdateState::None;
}
auto lock = LockShared();
if (!lock) {
return UpdateState::None;
}
SnapshotUpdateStatus update_status = ReadSnapshotUpdateStatus(lock.get());
auto state = update_status.state();
if (progress == nullptr) {
return state;
}
if (state == UpdateState::MergeCompleted) {
*progress = 100.0;
return state;
}
*progress = 0.0;
if (state != UpdateState::Merging) {
return state;
}
// Sum all the snapshot states as if the system consists of a single huge
// snapshots device, then compute the merge completion percentage of that
// device.
std::vector<std::string> snapshots;
if (!ListSnapshots(lock.get(), &snapshots)) {
LOG(ERROR) << "Could not list snapshots";
return state;
}
DmTargetSnapshot::Status fake_snapshots_status = {};
for (const auto& snapshot : snapshots) {
DmTargetSnapshot::Status current_status;
if (!QuerySnapshotStatus(snapshot, nullptr, &current_status)) continue;
fake_snapshots_status.sectors_allocated += current_status.sectors_allocated;
fake_snapshots_status.total_sectors += current_status.total_sectors;
fake_snapshots_status.metadata_sectors += current_status.metadata_sectors;
}
*progress = DmTargetSnapshot::MergePercent(fake_snapshots_status,
update_status.sectors_allocated());
return state;
}
bool SnapshotManager::ListSnapshots(LockedFile* lock, std::vector<std::string>* snapshots) {
CHECK(lock);
auto dir_path = metadata_dir_ + "/snapshots"s;
std::unique_ptr<DIR, decltype(&closedir)> dir(opendir(dir_path.c_str()), closedir);
if (!dir) {
PLOG(ERROR) << "opendir failed: " << dir_path;
return false;
}
struct dirent* dp;
while ((dp = readdir(dir.get())) != nullptr) {
if (dp->d_type != DT_REG) continue;
snapshots->emplace_back(dp->d_name);
}
return true;
}
bool SnapshotManager::IsSnapshotManagerNeeded() {
return access(kBootIndicatorPath, F_OK) == 0;
}
std::string SnapshotManager::GetGlobalRollbackIndicatorPath() {
return kRollbackIndicatorPath;
}
bool SnapshotManager::NeedSnapshotsInFirstStageMount() {
// If we fail to read, we'll wind up using CreateLogicalPartitions, which
// will create devices that look like the old slot, except with extra
// content at the end of each device. This will confuse dm-verity, and
// ultimately we'll fail to boot. Why not make it a fatal error and have
// the reason be clearer? Because the indicator file still exists, and
// if this was FATAL, reverting to the old slot would be broken.
auto slot = GetCurrentSlot();
if (slot != Slot::Target) {
if (slot == Slot::Source) {
// Device is rebooting into the original slot, so mark this as a
// rollback.
auto path = GetRollbackIndicatorPath();
if (!android::base::WriteStringToFile("1", path)) {
PLOG(ERROR) << "Unable to write rollback indicator: " << path;
} else {
LOG(INFO) << "Rollback detected, writing rollback indicator to " << path;
}
}
LOG(INFO) << "Not booting from new slot. Will not mount snapshots.";
return false;
}
// If we can't read the update state, it's unlikely anything else will
// succeed, so this is a fatal error. We'll eventually exhaust boot
// attempts and revert to the old slot.
auto lock = LockShared();
if (!lock) {
LOG(FATAL) << "Could not read update state to determine snapshot status";
return false;
}
switch (ReadUpdateState(lock.get())) {
case UpdateState::Unverified:
case UpdateState::Merging:
case UpdateState::MergeFailed:
return true;
default:
return false;
}
}
bool SnapshotManager::CreateLogicalAndSnapshotPartitions(
const std::string& super_device, const std::chrono::milliseconds& timeout_ms) {
LOG(INFO) << "Creating logical partitions with snapshots as needed";
auto lock = LockExclusive();
if (!lock) return false;
uint32_t slot = SlotNumberForSlotSuffix(device_->GetSlotSuffix());
return MapAllPartitions(lock.get(), super_device, slot, timeout_ms);
}
bool SnapshotManager::MapAllPartitions(LockedFile* lock, const std::string& super_device,
uint32_t slot, const std::chrono::milliseconds& timeout_ms) {
const auto& opener = device_->GetPartitionOpener();
auto metadata = android::fs_mgr::ReadMetadata(opener, super_device, slot);
if (!metadata) {
LOG(ERROR) << "Could not read dynamic partition metadata for device: " << super_device;
return false;
}
for (const auto& partition : metadata->partitions) {
if (GetPartitionGroupName(metadata->groups[partition.group_index]) == kCowGroupName) {
LOG(INFO) << "Skip mapping partition " << GetPartitionName(partition) << " in group "
<< kCowGroupName;
continue;
}
CreateLogicalPartitionParams params = {
.block_device = super_device,
.metadata = metadata.get(),
.partition = &partition,
.partition_opener = &opener,
.timeout_ms = timeout_ms,
};
if (!MapPartitionWithSnapshot(lock, std::move(params), SnapshotContext::Mount, nullptr)) {
return false;
}
}
LOG(INFO) << "Created logical partitions with snapshot.";
return true;
}
static std::chrono::milliseconds GetRemainingTime(
const std::chrono::milliseconds& timeout,
const std::chrono::time_point<std::chrono::steady_clock>& begin) {
// If no timeout is specified, execute all commands without specifying any timeout.
if (timeout.count() == 0) return std::chrono::milliseconds(0);
auto passed_time = std::chrono::steady_clock::now() - begin;
auto remaining_time = timeout - duration_cast<std::chrono::milliseconds>(passed_time);
if (remaining_time.count() <= 0) {
LOG(ERROR) << "MapPartitionWithSnapshot has reached timeout " << timeout.count() << "ms ("
<< remaining_time.count() << "ms remaining)";
// Return min() instead of remaining_time here because 0 is treated as a special value for
// no timeout, where the rest of the commands will still be executed.
return std::chrono::milliseconds::min();
}
return remaining_time;
}
bool SnapshotManager::MapPartitionWithSnapshot(LockedFile* lock,
CreateLogicalPartitionParams params,
SnapshotContext context, SnapshotPaths* paths) {
auto begin = std::chrono::steady_clock::now();
CHECK(lock);
if (params.GetPartitionName() != params.GetDeviceName()) {
LOG(ERROR) << "Mapping snapshot with a different name is unsupported: partition_name = "
<< params.GetPartitionName() << ", device_name = " << params.GetDeviceName();
return false;
}
// 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::MERGE_COMPLETED) {
live_snapshot_status.reset();
}
if (live_snapshot_status->state() == SnapshotState::NONE ||
live_snapshot_status->cow_partition_size() + live_snapshot_status->cow_file_size() ==
0) {
LOG(WARNING) << "Snapshot status for " << params.GetPartitionName()
<< " is invalid, ignoring: state = "
<< SnapshotState_Name(live_snapshot_status->state())
<< ", cow_partition_size = " << live_snapshot_status->cow_partition_size()
<< ", cow_file_size = " << live_snapshot_status->cow_file_size();
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;
// Map the base device with a different name to avoid collision.
params.device_name = GetBaseDeviceName(params.GetPartitionName());
}
AutoDeviceList created_devices;
// Create the base device for the snapshot, or if there is no snapshot, the
// device itself. This device consists of the real blocks in the super
// partition that this logical partition occupies.
auto& dm = DeviceMapper::Instance();
std::string base_path;
if (!CreateLogicalPartition(params, &base_path)) {
LOG(ERROR) << "Could not create logical partition " << params.GetPartitionName()
<< " as device " << params.GetDeviceName();
return false;
}
created_devices.EmplaceBack<AutoUnmapDevice>(&dm, params.GetDeviceName());
if (paths) {
paths->target_device = base_path;
}
if (!live_snapshot_status.has_value()) {
created_devices.Release();
return true;
}
// We don't have ueventd in first-stage init, so use device major:minor
// strings instead.
std::string base_device;
if (!dm.GetDeviceString(params.GetDeviceName(), &base_device)) {
LOG(ERROR) << "Could not determine major/minor for: " << params.GetDeviceName();
return false;
}
auto remaining_time = GetRemainingTime(params.timeout_ms, begin);
if (remaining_time.count() < 0) return false;
std::string cow_name;
CreateLogicalPartitionParams cow_params = params;
cow_params.timeout_ms = remaining_time;
if (!MapCowDevices(lock, cow_params, *live_snapshot_status, &created_devices, &cow_name)) {
return false;
}
std::string cow_device;
if (!GetMappedImageDeviceStringOrPath(cow_name, &cow_device)) {
LOG(ERROR) << "Could not determine major/minor for: " << cow_name;
return false;
}
if (paths) {
paths->cow_device_name = cow_name;
}
remaining_time = GetRemainingTime(params.timeout_ms, begin);
if (remaining_time.count() < 0) return false;
if (context == SnapshotContext::Update && live_snapshot_status->compression_enabled()) {
// Stop here, we can't run dm-user yet, the COW isn't built.
created_devices.Release();
return true;
}
if (live_snapshot_status->compression_enabled()) {
auto name = GetDmUserCowName(params.GetPartitionName());
std::string cow_path;
if (!GetMappedImageDevicePath(cow_name, &cow_path)) {
LOG(ERROR) << "Could not determine path for: " << cow_name;
return false;
}
// Ensure both |base_path| and |cow_path| are created, for snapuserd.
if (!WaitForDevice(base_path, remaining_time)) {
return false;
}
if (!WaitForDevice(cow_path, remaining_time)) {
return false;
}
std::string new_cow_device;
if (!MapDmUserCow(lock, name, cow_path, base_path, remaining_time, &new_cow_device)) {
LOG(ERROR) << "Could not map dm-user device for partition "
<< params.GetPartitionName();
return false;
}
created_devices.EmplaceBack<AutoUnmapDevice>(&dm, name);
remaining_time = GetRemainingTime(params.timeout_ms, begin);
if (remaining_time.count() < 0) return false;
cow_device = new_cow_device;
}
std::string path;
if (!MapSnapshot(lock, params.GetPartitionName(), base_device, cow_device, remaining_time,
&path)) {
LOG(ERROR) << "Could not map snapshot for partition: " << params.GetPartitionName();
return false;
}
// No need to add params.GetPartitionName() to created_devices since it is immediately released.
if (paths) {
paths->snapshot_device = path;
}
created_devices.Release();
LOG(INFO) << "Mapped " << params.GetPartitionName() << " as snapshot device at " << path;
return true;
}
bool SnapshotManager::UnmapPartitionWithSnapshot(LockedFile* lock,
const std::string& target_partition_name) {
CHECK(lock);
if (!UnmapSnapshot(lock, target_partition_name)) {
return false;
}
if (!UnmapCowDevices(lock, target_partition_name)) {
return false;
}
auto& dm = DeviceMapper::Instance();
std::string base_name = GetBaseDeviceName(target_partition_name);
if (!dm.DeleteDeviceIfExists(base_name)) {
LOG(ERROR) << "Cannot delete base device: " << base_name;
return false;
}
LOG(INFO) << "Successfully unmapped snapshot " << target_partition_name;
return true;
}
bool SnapshotManager::MapCowDevices(LockedFile* lock, const CreateLogicalPartitionParams& params,
const SnapshotStatus& snapshot_status,
AutoDeviceList* created_devices, std::string* cow_name) {
CHECK(lock);
CHECK(snapshot_status.cow_partition_size() + snapshot_status.cow_file_size() > 0);
auto begin = std::chrono::steady_clock::now();
std::string partition_name = params.GetPartitionName();
std::string cow_image_name = GetCowImageDeviceName(partition_name);
*cow_name = GetCowName(partition_name);
auto& dm = DeviceMapper::Instance();
// Map COW image if necessary.
if (snapshot_status.cow_file_size() > 0) {
if (!EnsureImageManager()) return false;
auto remaining_time = GetRemainingTime(params.timeout_ms, begin);
if (remaining_time.count() < 0) return false;
if (!MapCowImage(partition_name, remaining_time).has_value()) {
LOG(ERROR) << "Could not map cow image for partition: " << partition_name;
return false;
}
created_devices->EmplaceBack<AutoUnmapImage>(images_.get(), cow_image_name);
// If no COW partition exists, just return the image alone.
if (snapshot_status.cow_partition_size() == 0) {
*cow_name = std::move(cow_image_name);
LOG(INFO) << "Mapped COW image for " << partition_name << " at " << *cow_name;
return true;
}
}
auto remaining_time = GetRemainingTime(params.timeout_ms, begin);
if (remaining_time.count() < 0) return false;
CHECK(snapshot_status.cow_partition_size() > 0);
// Create the DmTable for the COW device. It is the DmTable of the COW partition plus
// COW image device as the last extent.
CreateLogicalPartitionParams cow_partition_params = params;
cow_partition_params.partition = nullptr;
cow_partition_params.partition_name = *cow_name;
cow_partition_params.device_name.clear();
DmTable table;
if (!CreateDmTable(cow_partition_params, &table)) {
return false;
}
// If the COW image exists, append it as the last extent.
if (snapshot_status.cow_file_size() > 0) {
std::string cow_image_device;
if (!GetMappedImageDeviceStringOrPath(cow_image_name, &cow_image_device)) {
LOG(ERROR) << "Cannot determine major/minor for: " << cow_image_name;
return false;
}
auto cow_partition_sectors = snapshot_status.cow_partition_size() / kSectorSize;
auto cow_image_sectors = snapshot_status.cow_file_size() / kSectorSize;
table.Emplace<DmTargetLinear>(cow_partition_sectors, cow_image_sectors, cow_image_device,
0);
}
// We have created the DmTable now. Map it.
std::string cow_path;
if (!dm.CreateDevice(*cow_name, table, &cow_path, remaining_time)) {
LOG(ERROR) << "Could not create COW device: " << *cow_name;
return false;
}
created_devices->EmplaceBack<AutoUnmapDevice>(&dm, *cow_name);
LOG(INFO) << "Mapped COW device for " << params.GetPartitionName() << " at " << cow_path;
return true;
}
bool SnapshotManager::UnmapCowDevices(LockedFile* lock, const std::string& name) {
CHECK(lock);
if (!EnsureImageManager()) return false;
auto& dm = DeviceMapper::Instance();
if (IsCompressionEnabled() && !UnmapDmUserDevice(name)) {
return false;
}
auto cow_name = GetCowName(name);
if (!dm.DeleteDeviceIfExists(cow_name)) {
LOG(ERROR) << "Cannot unmap " << cow_name;
return false;
}
std::string cow_image_name = GetCowImageDeviceName(name);
if (!images_->UnmapImageIfExists(cow_image_name)) {
LOG(ERROR) << "Cannot unmap image " << cow_image_name;
return false;
}
return true;
}
bool SnapshotManager::UnmapDmUserDevice(const std::string& snapshot_name) {
auto& dm = DeviceMapper::Instance();
if (!EnsureSnapuserdConnected()) {
return false;
}
auto dm_user_name = GetDmUserCowName(snapshot_name);
if (dm.GetState(dm_user_name) == DmDeviceState::INVALID) {
return true;
}
if (!dm.DeleteDeviceIfExists(dm_user_name)) {
LOG(ERROR) << "Cannot unmap " << dm_user_name;
return false;
}
if (!snapuserd_client_->WaitForDeviceDelete(dm_user_name)) {
LOG(ERROR) << "Failed to wait for " << dm_user_name << " control device to delete";
return false;
}
// Ensure the control device is gone so we don't run into ABA problems.
auto control_device = "/dev/dm-user/" + dm_user_name;
if (!android::fs_mgr::WaitForFileDeleted(control_device, 10s)) {
LOG(ERROR) << "Timed out waiting for " << control_device << " to unlink";
return false;
}
return true;
}
bool SnapshotManager::MapAllSnapshots(const std::chrono::milliseconds& timeout_ms) {
auto lock = LockExclusive();
if (!lock) return false;
auto state = ReadUpdateState(lock.get());
if (state == UpdateState::Unverified) {
if (GetCurrentSlot() == Slot::Target) {
LOG(ERROR) << "Cannot call MapAllSnapshots when booting from the target slot.";
return false;
}
} else if (state != UpdateState::Initiated) {
LOG(ERROR) << "Cannot call MapAllSnapshots from update state: " << state;
return false;
}
if (!UnmapAllSnapshots(lock.get())) {
return false;
}
uint32_t slot = SlotNumberForSlotSuffix(device_->GetOtherSlotSuffix());
return MapAllPartitions(lock.get(), device_->GetSuperDevice(slot), slot, timeout_ms);
}
bool SnapshotManager::UnmapAllSnapshots() {
auto lock = LockExclusive();
if (!lock) return false;
return UnmapAllSnapshots(lock.get());
}
bool SnapshotManager::UnmapAllSnapshots(LockedFile* lock) {
std::vector<std::string> snapshots;
if (!ListSnapshots(lock, &snapshots)) {
return false;
}
for (const auto& snapshot : snapshots) {
if (!UnmapPartitionWithSnapshot(lock, snapshot)) {
LOG(ERROR) << "Failed to unmap snapshot: " << snapshot;
return false;
}
}
return true;
}
auto SnapshotManager::OpenFile(const std::string& file, int lock_flags)
-> std::unique_ptr<LockedFile> {
unique_fd fd(open(file.c_str(), O_RDONLY | O_CLOEXEC | O_NOFOLLOW));
if (fd < 0) {
PLOG(ERROR) << "Open failed: " << file;
return nullptr;
}
if (lock_flags != 0 && TEMP_FAILURE_RETRY(flock(fd, lock_flags)) < 0) {
PLOG(ERROR) << "Acquire flock failed: " << file;
return nullptr;
}
// For simplicity, we want to CHECK that lock_mode == LOCK_EX, in some
// calls, so strip extra flags.
int lock_mode = lock_flags & (LOCK_EX | LOCK_SH);
return std::make_unique<LockedFile>(file, std::move(fd), lock_mode);
}
SnapshotManager::LockedFile::~LockedFile() {
if (TEMP_FAILURE_RETRY(flock(fd_, LOCK_UN)) < 0) {
PLOG(ERROR) << "Failed to unlock file: " << path_;
}
}
std::string SnapshotManager::GetStateFilePath() const {
return metadata_dir_ + "/state"s;
}
std::string SnapshotManager::GetMergeStateFilePath() const {
return metadata_dir_ + "/merge_state"s;
}
std::string SnapshotManager::GetLockPath() const {
return metadata_dir_;
}
std::unique_ptr<SnapshotManager::LockedFile> SnapshotManager::OpenLock(int lock_flags) {
auto lock_file = GetLockPath();
return OpenFile(lock_file, lock_flags);
}
std::unique_ptr<SnapshotManager::LockedFile> SnapshotManager::LockShared() {
return OpenLock(LOCK_SH);
}
std::unique_ptr<SnapshotManager::LockedFile> SnapshotManager::LockExclusive() {
return OpenLock(LOCK_EX);
}
static UpdateState UpdateStateFromString(const std::string& contents) {
if (contents.empty() || contents == "none") {
return UpdateState::None;
} else if (contents == "initiated") {
return UpdateState::Initiated;
} else if (contents == "unverified") {
return UpdateState::Unverified;
} else if (contents == "merging") {
return UpdateState::Merging;
} else if (contents == "merge-completed") {
return UpdateState::MergeCompleted;
} else if (contents == "merge-needs-reboot") {
return UpdateState::MergeNeedsReboot;
} else if (contents == "merge-failed") {
return UpdateState::MergeFailed;
} else if (contents == "cancelled") {
return UpdateState::Cancelled;
} else {
LOG(ERROR) << "Unknown merge state in update state file: \"" << contents << "\"";
return UpdateState::None;
}
}
std::ostream& operator<<(std::ostream& os, UpdateState state) {
switch (state) {
case UpdateState::None:
return os << "none";
case UpdateState::Initiated:
return os << "initiated";
case UpdateState::Unverified:
return os << "unverified";
case UpdateState::Merging:
return os << "merging";
case UpdateState::MergeCompleted:
return os << "merge-completed";
case UpdateState::MergeNeedsReboot:
return os << "merge-needs-reboot";
case UpdateState::MergeFailed:
return os << "merge-failed";
case UpdateState::Cancelled:
return os << "cancelled";
default:
LOG(ERROR) << "Unknown update state: " << static_cast<uint32_t>(state);
return os;
}
}
UpdateState SnapshotManager::ReadUpdateState(LockedFile* lock) {
SnapshotUpdateStatus status = ReadSnapshotUpdateStatus(lock);
return status.state();
}
SnapshotUpdateStatus SnapshotManager::ReadSnapshotUpdateStatus(LockedFile* lock) {
CHECK(lock);
SnapshotUpdateStatus status = {};
std::string contents;
if (!android::base::ReadFileToString(GetStateFilePath(), &contents)) {
PLOG(ERROR) << "Read state file failed";
status.set_state(UpdateState::None);
return status;
}
if (!status.ParseFromString(contents)) {
LOG(WARNING) << "Unable to parse state file as SnapshotUpdateStatus, using the old format";
// Try to rollback to legacy file to support devices that are
// currently using the old file format.
// TODO(b/147409432)
status.set_state(UpdateStateFromString(contents));
}
return status;
}
bool SnapshotManager::WriteUpdateState(LockedFile* lock, UpdateState state) {
SnapshotUpdateStatus status = {};
status.set_state(state);
status.set_compression_enabled(IsCompressionEnabled());
return WriteSnapshotUpdateStatus(lock, status);
}
bool SnapshotManager::WriteSnapshotUpdateStatus(LockedFile* lock,
const SnapshotUpdateStatus& status) {
CHECK(lock);
CHECK(lock->lock_mode() == LOCK_EX);
std::string contents;
if (!status.SerializeToString(&contents)) {
LOG(ERROR) << "Unable to serialize SnapshotUpdateStatus.";
return false;
}
#ifdef LIBSNAPSHOT_USE_HAL
auto merge_status = MergeStatus::UNKNOWN;
switch (status.state()) {
// The needs-reboot and completed cases imply that /data and /metadata
// can be safely wiped, so we don't report a merge status.
case UpdateState::None:
case UpdateState::MergeNeedsReboot:
case UpdateState::MergeCompleted:
case UpdateState::Initiated:
merge_status = MergeStatus::NONE;
break;
case UpdateState::Unverified:
merge_status = MergeStatus::SNAPSHOTTED;
break;
case UpdateState::Merging:
case UpdateState::MergeFailed:
merge_status = MergeStatus::MERGING;
break;
default:
// Note that Cancelled flows to here - it is never written, since
// it only communicates a transient state to the caller.
LOG(ERROR) << "Unexpected update status: " << status.state();
break;
}
bool set_before_write =
merge_status == MergeStatus::SNAPSHOTTED || merge_status == MergeStatus::MERGING;
if (set_before_write && !device_->SetBootControlMergeStatus(merge_status)) {
return false;
}
#endif
if (!WriteStringToFileAtomic(contents, GetStateFilePath())) {
PLOG(ERROR) << "Could not write to state file";
return false;
}
#ifdef LIBSNAPSHOT_USE_HAL
if (!set_before_write && !device_->SetBootControlMergeStatus(merge_status)) {
return false;
}
#endif
return true;
}
std::string SnapshotManager::GetSnapshotStatusFilePath(const std::string& name) {
auto file = metadata_dir_ + "/snapshots/"s + name;
return file;
}
bool SnapshotManager::ReadSnapshotStatus(LockedFile* lock, const std::string& name,
SnapshotStatus* status) {
CHECK(lock);
auto path = GetSnapshotStatusFilePath(name);
unique_fd fd(open(path.c_str(), O_RDONLY | O_CLOEXEC | O_NOFOLLOW));
if (fd < 0) {
PLOG(ERROR) << "Open failed: " << path;
return false;
}
if (!status->ParseFromFileDescriptor(fd.get())) {
PLOG(ERROR) << "Unable to parse " << path << " as SnapshotStatus";
return false;
}
if (status->name() != name) {
LOG(WARNING) << "Found snapshot status named " << status->name() << " in " << path;
status->set_name(name);
}
return true;
}
bool SnapshotManager::WriteSnapshotStatus(LockedFile* lock, const SnapshotStatus& status) {
// The caller must take an exclusive lock to modify snapshots.
CHECK(lock);
CHECK(lock->lock_mode() == LOCK_EX);
CHECK(!status.name().empty());
auto path = GetSnapshotStatusFilePath(status.name());
std::string content;
if (!status.SerializeToString(&content)) {
LOG(ERROR) << "Unable to serialize SnapshotStatus for " << status.name();
return false;
}
if (!WriteStringToFileAtomic(content, path)) {
PLOG(ERROR) << "Unable to write SnapshotStatus to " << path;
return false;
}
return true;
}
std::string SnapshotManager::GetSnapshotDeviceName(const std::string& snapshot_name,
const SnapshotStatus& status) {
if (status.device_size() != status.snapshot_size()) {
return GetSnapshotExtraDeviceName(snapshot_name);
}
return snapshot_name;
}
bool SnapshotManager::EnsureImageManager() {
if (images_) return true;
// For now, use a preset timeout.
images_ = android::fiemap::IImageManager::Open(gsid_dir_, 15000ms);
if (!images_) {
LOG(ERROR) << "Could not open ImageManager";
return false;
}
return true;
}
bool SnapshotManager::EnsureSnapuserdConnected() {
if (snapuserd_client_) {
return true;
}
if (!use_first_stage_snapuserd_ && !EnsureSnapuserdStarted()) {
return false;
}
snapuserd_client_ = SnapuserdClient::Connect(kSnapuserdSocket, 10s);
if (!snapuserd_client_) {
LOG(ERROR) << "Unable to connect to snapuserd";
return false;
}
return true;
}
bool SnapshotManager::ForceLocalImageManager() {
images_ = android::fiemap::ImageManager::Open(gsid_dir_);
if (!images_) {
LOG(ERROR) << "Could not open ImageManager";
return false;
}
has_local_image_manager_ = true;
return true;
}
static void UnmapAndDeleteCowPartition(MetadataBuilder* current_metadata) {
auto& dm = DeviceMapper::Instance();
std::vector<std::string> to_delete;
for (auto* existing_cow_partition : current_metadata->ListPartitionsInGroup(kCowGroupName)) {
if (!dm.DeleteDeviceIfExists(existing_cow_partition->name())) {
LOG(WARNING) << existing_cow_partition->name()
<< " cannot be unmapped and its space cannot be reclaimed";
continue;
}
to_delete.push_back(existing_cow_partition->name());
}
for (const auto& name : to_delete) {
current_metadata->RemovePartition(name);
}
}
static Return AddRequiredSpace(Return orig,
const std::map<std::string, SnapshotStatus>& all_snapshot_status) {
if (orig.error_code() != Return::ErrorCode::NO_SPACE) {
return orig;
}
uint64_t sum = 0;
for (auto&& [name, status] : all_snapshot_status) {
sum += status.cow_file_size();
}
return Return::NoSpace(sum);
}
Return SnapshotManager::CreateUpdateSnapshots(const DeltaArchiveManifest& manifest) {
auto lock = LockExclusive();
if (!lock) return Return::Error();
// TODO(b/134949511): remove this check. Right now, with overlayfs mounted, the scratch
// partition takes up a big chunk of space in super, causing COW images to be created on
// retrofit Virtual A/B devices.
if (device_->IsOverlayfsSetup()) {
LOG(ERROR) << "Cannot create update snapshots with overlayfs setup. Run `adb enable-verity`"
<< ", reboot, then try again.";
return Return::Error();
}
const auto& opener = device_->GetPartitionOpener();
auto current_suffix = device_->GetSlotSuffix();
uint32_t current_slot = SlotNumberForSlotSuffix(current_suffix);
auto target_suffix = device_->GetOtherSlotSuffix();
uint32_t target_slot = SlotNumberForSlotSuffix(target_suffix);
auto current_super = device_->GetSuperDevice(current_slot);
auto current_metadata = MetadataBuilder::New(opener, current_super, current_slot);
if (current_metadata == nullptr) {
LOG(ERROR) << "Cannot create metadata builder.";
return Return::Error();
}
auto target_metadata =
MetadataBuilder::NewForUpdate(opener, current_super, current_slot, target_slot);
if (target_metadata == nullptr) {
LOG(ERROR) << "Cannot create target metadata builder.";
return Return::Error();
}
// Delete partitions with target suffix in |current_metadata|. Otherwise,
// partition_cow_creator recognizes these left-over partitions as used space.
for (const auto& group_name : current_metadata->ListGroups()) {
if (android::base::EndsWith(group_name, target_suffix)) {
current_metadata->RemoveGroupAndPartitions(group_name);
}
}
SnapshotMetadataUpdater metadata_updater(target_metadata.get(), target_slot, manifest);
if (!metadata_updater.Update()) {
LOG(ERROR) << "Cannot calculate new metadata.";
return Return::Error();
}
// Delete previous COW partitions in current_metadata so that PartitionCowCreator marks those as
// free regions.
UnmapAndDeleteCowPartition(current_metadata.get());
// Check that all these metadata is not retrofit dynamic partitions. Snapshots on
// devices with retrofit dynamic partitions does not make sense.
// This ensures that current_metadata->GetFreeRegions() uses the same device
// indices as target_metadata (i.e. 0 -> "super").
// This is also assumed in MapCowDevices() call below.
CHECK(current_metadata->GetBlockDevicePartitionName(0) == LP_METADATA_DEFAULT_PARTITION_NAME &&
target_metadata->GetBlockDevicePartitionName(0) == LP_METADATA_DEFAULT_PARTITION_NAME);
std::map<std::string, SnapshotStatus> all_snapshot_status;
// In case of error, automatically delete devices that are created along the way.
// Note that "lock" is destroyed after "created_devices", so it is safe to use |lock| for
// these devices.
AutoDeviceList created_devices;
PartitionCowCreator cow_creator{
.target_metadata = target_metadata.get(),
.target_suffix = target_suffix,
.target_partition = nullptr,
.current_metadata = current_metadata.get(),
.current_suffix = current_suffix,
.update = nullptr,
.extra_extents = {},
.compression_enabled = IsCompressionEnabled(),
};
auto ret = CreateUpdateSnapshotsInternal(lock.get(), manifest, &cow_creator, &created_devices,
&all_snapshot_status);
if (!ret.is_ok()) return ret;
auto exported_target_metadata = target_metadata->Export();
if (exported_target_metadata == nullptr) {
LOG(ERROR) << "Cannot export target metadata";
return Return::Error();
}
ret = InitializeUpdateSnapshots(lock.get(), target_metadata.get(),
exported_target_metadata.get(), target_suffix,
all_snapshot_status);
if (!ret.is_ok()) return ret;
if (!UpdatePartitionTable(opener, device_->GetSuperDevice(target_slot),
*exported_target_metadata, target_slot)) {
LOG(ERROR) << "Cannot write target metadata";
return Return::Error();
}
created_devices.Release();
LOG(INFO) << "Successfully created all snapshots for target slot " << target_suffix;
return Return::Ok();
}
Return SnapshotManager::CreateUpdateSnapshotsInternal(
LockedFile* lock, const DeltaArchiveManifest& manifest, PartitionCowCreator* cow_creator,
AutoDeviceList* created_devices,
std::map<std::string, SnapshotStatus>* all_snapshot_status) {
CHECK(lock);
auto* target_metadata = cow_creator->target_metadata;
const auto& target_suffix = cow_creator->target_suffix;
if (!target_metadata->AddGroup(kCowGroupName, 0)) {
LOG(ERROR) << "Cannot add group " << kCowGroupName;
return Return::Error();
}
std::map<std::string, const PartitionUpdate*> partition_map;
std::map<std::string, std::vector<Extent>> extra_extents_map;
for (const auto& partition_update : manifest.partitions()) {
auto suffixed_name = partition_update.partition_name() + target_suffix;
auto&& [it, inserted] = partition_map.emplace(suffixed_name, &partition_update);
if (!inserted) {
LOG(ERROR) << "Duplicated partition " << partition_update.partition_name()
<< " in update manifest.";
return Return::Error();
}
auto& extra_extents = extra_extents_map[suffixed_name];
if (partition_update.has_hash_tree_extent()) {
extra_extents.push_back(partition_update.hash_tree_extent());
}
if (partition_update.has_fec_extent()) {
extra_extents.push_back(partition_update.fec_extent());
}
}
for (auto* target_partition : ListPartitionsWithSuffix(target_metadata, target_suffix)) {
cow_creator->target_partition = target_partition;
cow_creator->update = nullptr;
auto iter = partition_map.find(target_partition->name());
if (iter != partition_map.end()) {
cow_creator->update = iter->second;
} else {
LOG(INFO) << target_partition->name()
<< " isn't included in the payload, skipping the cow creation.";
continue;
}
cow_creator->extra_extents.clear();
auto extra_extents_it = extra_extents_map.find(target_partition->name());
if (extra_extents_it != extra_extents_map.end()) {
cow_creator->extra_extents = std::move(extra_extents_it->second);
}
// Compute the device sizes for the partition.
auto cow_creator_ret = cow_creator->Run();
if (!cow_creator_ret.has_value()) {
LOG(ERROR) << "PartitionCowCreator returned no value for " << target_partition->name();
return Return::Error();
}
LOG(INFO) << "For partition " << target_partition->name()
<< ", device size = " << cow_creator_ret->snapshot_status.device_size()
<< ", snapshot size = " << cow_creator_ret->snapshot_status.snapshot_size()
<< ", cow partition size = "
<< cow_creator_ret->snapshot_status.cow_partition_size()
<< ", cow file size = " << cow_creator_ret->snapshot_status.cow_file_size();
// Delete any existing snapshot before re-creating one.
if (!DeleteSnapshot(lock, target_partition->name())) {
LOG(ERROR) << "Cannot delete existing snapshot before creating a new one for partition "
<< target_partition->name();
return Return::Error();
}
// It is possible that the whole partition uses free space in super, and snapshot / COW
// would not be needed. In this case, skip the partition.
bool needs_snapshot = cow_creator_ret->snapshot_status.snapshot_size() > 0;
bool needs_cow = (cow_creator_ret->snapshot_status.cow_partition_size() +
cow_creator_ret->snapshot_status.cow_file_size()) > 0;
CHECK(needs_snapshot == needs_cow);
if (!needs_snapshot) {
LOG(INFO) << "Skip creating snapshot for partition " << target_partition->name()
<< "because nothing needs to be snapshotted.";
continue;
}
// Store these device sizes to snapshot status file.
if (!CreateSnapshot(lock, &cow_creator_ret->snapshot_status)) {
return Return::Error();
}
created_devices->EmplaceBack<AutoDeleteSnapshot>(this, lock, target_partition->name());
// Create the COW partition. That is, use any remaining free space in super partition before
// creating the COW images.
if (cow_creator_ret->snapshot_status.cow_partition_size() > 0) {
CHECK(cow_creator_ret->snapshot_status.cow_partition_size() % kSectorSize == 0)
<< "cow_partition_size == "
<< cow_creator_ret->snapshot_status.cow_partition_size()
<< " is not a multiple of sector size " << kSectorSize;
auto cow_partition = target_metadata->AddPartition(GetCowName(target_partition->name()),
kCowGroupName, 0 /* flags */);
if (cow_partition == nullptr) {
return Return::Error();
}
if (!target_metadata->ResizePartition(
cow_partition, cow_creator_ret->snapshot_status.cow_partition_size(),
cow_creator_ret->cow_partition_usable_regions)) {
LOG(ERROR) << "Cannot create COW partition on metadata with size "
<< cow_creator_ret->snapshot_status.cow_partition_size();
return Return::Error();
}
// Only the in-memory target_metadata is modified; nothing to clean up if there is an
// error in the future.
}
all_snapshot_status->emplace(target_partition->name(),
std::move(cow_creator_ret->snapshot_status));
LOG(INFO) << "Successfully created snapshot partition for " << target_partition->name();
}
LOG(INFO) << "Allocating CoW images.";
for (auto&& [name, snapshot_status] : *all_snapshot_status) {
// Create the backing COW image if necessary.
if (snapshot_status.cow_file_size() > 0) {
auto ret = CreateCowImage(lock, name);
if (!ret.is_ok()) return AddRequiredSpace(ret, *all_snapshot_status);
}
LOG(INFO) << "Successfully created snapshot for " << name;
}
return Return::Ok();
}
Return SnapshotManager::InitializeUpdateSnapshots(
LockedFile* lock, MetadataBuilder* target_metadata,
const LpMetadata* exported_target_metadata, const std::string& target_suffix,
const std::map<std::string, SnapshotStatus>& all_snapshot_status) {
CHECK(lock);
CreateLogicalPartitionParams cow_params{
.block_device = LP_METADATA_DEFAULT_PARTITION_NAME,
.metadata = exported_target_metadata,
.timeout_ms = std::chrono::milliseconds::max(),