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Merge changes I06043f8e,I872f271c 

* changes:
  libsnapshot: Use a two-phase merge for VABC.
  libsnapshot: Pass the correct source device to snapuserd.
This commit is contained in:
David Anderson 2021-01-21 21:10:38 +00:00 committed by Gerrit Code Review
parent 531e15e38c 86ba14be16
commit 4787c1fa28
6 changed files with 254 additions and 29 deletions
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22
fs_mgr/libsnapshot/android/snapshot/snapshot.proto
View File

@ -34,7 +34,19 @@ enum SnapshotState {
MERGE_COMPLETED = 3;
}
// Next: 10
// Next: 3
enum MergePhase {
// No merge is in progress.
NO_MERGE = 0;
// Shrunk partitions can merge.
FIRST_PHASE = 1;
// Grown partitions can merge.
SECOND_PHASE = 2;
}
// Next: 11
message SnapshotStatus {
// Name of the snapshot. This is usually the name of the snapshotted
// logical partition; for example, "system_b".
@ -87,6 +99,9 @@ message SnapshotStatus {
// True if compression is enabled, false otherwise.
bool compression_enabled = 9;
// The old partition size (if none existed, this will be zero).
uint64 old_partition_size = 10;
}
// Next: 8
@ -118,7 +133,7 @@ enum UpdateState {
Cancelled = 7;
};
// Next: 6
// Next: 7
message SnapshotUpdateStatus {
UpdateState state = 1;
@ -136,6 +151,9 @@ message SnapshotUpdateStatus {
// Whether compression/dm-user was used for any snapshots.
bool compression_enabled = 5;
// Merge phase (if state == MERGING).
MergePhase merge_phase = 6;
}
// Next: 4

13
fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
View File

@ -463,6 +463,10 @@ class SnapshotManager final : public ISnapshotManager {
const std::string& base_device, const std::chrono::milliseconds& timeout_ms,
std::string* path);
// Map the source device used for dm-user.
bool MapSourceDevice(LockedFile* lock, const std::string& name,
const std::chrono::milliseconds& timeout_ms, std::string* path);
// Map a COW image that was previous created with CreateCowImage.
std::optional<std::string> MapCowImage(const std::string& name,
const std::chrono::milliseconds& timeout_ms);
@ -521,11 +525,13 @@ class SnapshotManager final : public ISnapshotManager {
std::string GetMergeStateFilePath() const;
// Helpers for merging.
bool MergeSecondPhaseSnapshots(LockedFile* lock);
bool SwitchSnapshotToMerge(LockedFile* lock, const std::string& name);
bool RewriteSnapshotDeviceTable(const std::string& dm_name);
bool MarkSnapshotMergeCompleted(LockedFile* snapshot_lock, const std::string& snapshot_name);
void AcknowledgeMergeSuccess(LockedFile* lock);
void AcknowledgeMergeFailure();
MergePhase DecideMergePhase(const SnapshotStatus& status);
std::unique_ptr<LpMetadata> ReadCurrentMetadata();
enum class MetadataPartitionState {
@ -558,7 +564,8 @@ class SnapshotManager final : public ISnapshotManager {
// UpdateState::MergeNeedsReboot
UpdateState CheckMergeState(const std::function<bool()>& before_cancel);
UpdateState CheckMergeState(LockedFile* lock, const std::function<bool()>& before_cancel);
UpdateState CheckTargetMergeState(LockedFile* lock, const std::string& name);
UpdateState CheckTargetMergeState(LockedFile* lock, const std::string& name,
const SnapshotUpdateStatus& update_status);
// Interact with status files under /metadata/ota/snapshots.
bool WriteSnapshotStatus(LockedFile* lock, const SnapshotStatus& status);
@ -568,6 +575,9 @@ class SnapshotManager final : public ISnapshotManager {
std::string GetSnapshotBootIndicatorPath();
std::string GetRollbackIndicatorPath();
std::string GetForwardMergeIndicatorPath();
std::string GetOldPartitionMetadataPath();
const LpMetadata* ReadOldPartitionMetadata(LockedFile* lock);
bool MapAllPartitions(LockedFile* lock, const std::string& super_device, uint32_t slot,
const std::chrono::milliseconds& timeout_ms);
@ -716,6 +726,7 @@ class SnapshotManager final : public ISnapshotManager {
bool in_factory_data_reset_ = false;
std::function<bool(const std::string&)> uevent_regen_callback_;
std::unique_ptr<SnapuserdClient> snapuserd_client_;
std::unique_ptr<LpMetadata> old_partition_metadata_;
};
} // namespace snapshot

234
fs_mgr/libsnapshot/snapshot.cpp
View File

@ -132,6 +132,10 @@ static std::string GetBaseDeviceName(const std::string& partition_name) {
return partition_name + "-base";
}
static std::string GetSourceDeviceName(const std::string& partition_name) {
return partition_name + "-src";
}
bool SnapshotManager::BeginUpdate() {
bool needs_merge = false;
if (!TryCancelUpdate(&needs_merge)) {
@ -153,6 +157,9 @@ bool SnapshotManager::BeginUpdate() {
images_->RemoveAllImages();
}
// Clear any cached metadata (this allows re-using one manager across tests).
old_partition_metadata_ = nullptr;
auto state = ReadUpdateState(file.get());
if (state != UpdateState::None) {
LOG(ERROR) << "An update is already in progress, cannot begin a new update";
@ -251,6 +258,7 @@ bool SnapshotManager::RemoveAllUpdateState(LockedFile* lock, const std::function
GetSnapshotBootIndicatorPath(),
GetRollbackIndicatorPath(),
GetForwardMergeIndicatorPath(),
GetOldPartitionMetadataPath(),
};
for (const auto& file : files) {
RemoveFileIfExists(file);
@ -475,7 +483,8 @@ bool SnapshotManager::MapSnapshot(LockedFile* lock, const std::string& name,
// have completed merging, but the start of the merge process is considered
// atomic.
SnapshotStorageMode mode;
switch (ReadUpdateState(lock)) {
SnapshotUpdateStatus update_status = ReadSnapshotUpdateStatus(lock);
switch (update_status.state()) {
case UpdateState::MergeCompleted:
case UpdateState::MergeNeedsReboot:
LOG(ERROR) << "Should not create a snapshot device for " << name
@ -485,7 +494,11 @@ bool SnapshotManager::MapSnapshot(LockedFile* lock, const std::string& name,
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;
if (DecideMergePhase(status) == update_status.merge_phase()) {
mode = SnapshotStorageMode::Merge;
} else {
mode = SnapshotStorageMode::Persistent;
}
break;
default:
mode = SnapshotStorageMode::Persistent;
@ -526,6 +539,36 @@ std::optional<std::string> SnapshotManager::MapCowImage(
return std::nullopt;
}
bool SnapshotManager::MapSourceDevice(LockedFile* lock, const std::string& name,
const std::chrono::milliseconds& timeout_ms,
std::string* path) {
CHECK(lock);
auto metadata = ReadOldPartitionMetadata(lock);
if (!metadata) {
LOG(ERROR) << "Could not map source device due to missing or corrupt metadata";
return false;
}
auto old_name = GetOtherPartitionName(name);
auto slot_suffix = device_->GetSlotSuffix();
auto slot = SlotNumberForSlotSuffix(slot_suffix);
CreateLogicalPartitionParams params = {
.block_device = device_->GetSuperDevice(slot),
.metadata = metadata,
.partition_name = old_name,
.timeout_ms = timeout_ms,
.device_name = GetSourceDeviceName(name),
.partition_opener = &device_->GetPartitionOpener(),
};
if (!CreateLogicalPartition(std::move(params), path)) {
LOG(ERROR) << "Could not create source device for snapshot " << name;
return false;
}
return true;
}
bool SnapshotManager::UnmapSnapshot(LockedFile* lock, const std::string& name) {
CHECK(lock);
@ -640,6 +683,8 @@ bool SnapshotManager::InitiateMerge(uint64_t* cow_file_size) {
bool compression_enabled = false;
std::vector<std::string> first_merge_group;
uint64_t total_cow_file_size = 0;
DmTargetSnapshot::Status initial_target_values = {};
for (const auto& snapshot : snapshots) {
@ -658,6 +703,9 @@ bool SnapshotManager::InitiateMerge(uint64_t* cow_file_size) {
total_cow_file_size += snapshot_status.cow_file_size();
compression_enabled |= snapshot_status.compression_enabled();
if (DecideMergePhase(snapshot_status) == MergePhase::FIRST_PHASE) {
first_merge_group.emplace_back(snapshot);
}
}
if (cow_file_size) {
@ -671,14 +719,26 @@ bool SnapshotManager::InitiateMerge(uint64_t* cow_file_size) {
initial_status.set_metadata_sectors(initial_target_values.metadata_sectors);
initial_status.set_compression_enabled(compression_enabled);
// If any partitions shrunk, we need to merge them before we merge any other
// partitions (see b/177935716). Otherwise, a merge from another partition
// may overwrite the source block of a copy operation.
const std::vector<std::string>* merge_group;
if (first_merge_group.empty()) {
merge_group = &snapshots;
initial_status.set_merge_phase(MergePhase::SECOND_PHASE);
} else {
merge_group = &first_merge_group;
initial_status.set_merge_phase(MergePhase::FIRST_PHASE);
}
// Point of no return - mark that we're starting a merge. From now on every
// snapshot must be a merge target.
// eligible snapshot must be a merge target.
if (!WriteSnapshotUpdateStatus(lock.get(), initial_status)) {
return false;
}
bool rewrote_all = true;
for (const auto& snapshot : snapshots) {
for (const auto& snapshot : *merge_group) {
// 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.
@ -869,13 +929,13 @@ UpdateState SnapshotManager::CheckMergeState(const std::function<bool()>& before
UpdateState SnapshotManager::CheckMergeState(LockedFile* lock,
const std::function<bool()>& before_cancel) {
UpdateState state = ReadUpdateState(lock);
switch (state) {
SnapshotUpdateStatus update_status = ReadSnapshotUpdateStatus(lock);
switch (update_status.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;
return update_status.state();
case UpdateState::Merging:
case UpdateState::MergeNeedsReboot:
@ -892,10 +952,10 @@ UpdateState SnapshotManager::CheckMergeState(LockedFile* lock,
if (HandleCancelledUpdate(lock, before_cancel)) {
return UpdateState::Cancelled;
}
return state;
return update_status.state();
default:
return state;
return update_status.state();
}
std::vector<std::string> snapshots;
@ -907,8 +967,9 @@ UpdateState SnapshotManager::CheckMergeState(LockedFile* lock,
bool failed = false;
bool merging = false;
bool needs_reboot = false;
bool wrong_phase = false;
for (const auto& snapshot : snapshots) {
UpdateState snapshot_state = CheckTargetMergeState(lock, snapshot);
UpdateState snapshot_state = CheckTargetMergeState(lock, snapshot, update_status);
switch (snapshot_state) {
case UpdateState::MergeFailed:
failed = true;
@ -924,6 +985,9 @@ UpdateState SnapshotManager::CheckMergeState(LockedFile* lock,
case UpdateState::Cancelled:
cancelled = true;
break;
case UpdateState::None:
wrong_phase = true;
break;
default:
LOG(ERROR) << "Unknown merge status for \"" << snapshot << "\": "
<< "\"" << snapshot_state << "\"";
@ -943,6 +1007,14 @@ UpdateState SnapshotManager::CheckMergeState(LockedFile* lock,
// it in WaitForMerge rather than here and elsewhere.
return UpdateState::MergeFailed;
}
if (wrong_phase) {
// If we got here, no other partitions are being merged, and nothing
// failed to merge. It's safe to move to the next merge phase.
if (!MergeSecondPhaseSnapshots(lock)) {
return UpdateState::MergeFailed;
}
return UpdateState::Merging;
}
if (needs_reboot) {
WriteUpdateState(lock, UpdateState::MergeNeedsReboot);
return UpdateState::MergeNeedsReboot;
@ -958,7 +1030,8 @@ UpdateState SnapshotManager::CheckMergeState(LockedFile* lock,
return UpdateState::MergeCompleted;
}
UpdateState SnapshotManager::CheckTargetMergeState(LockedFile* lock, const std::string& name) {
UpdateState SnapshotManager::CheckTargetMergeState(LockedFile* lock, const std::string& name,
const SnapshotUpdateStatus& update_status) {
SnapshotStatus snapshot_status;
if (!ReadSnapshotStatus(lock, name, &snapshot_status)) {
return UpdateState::MergeFailed;
@ -980,7 +1053,7 @@ UpdateState SnapshotManager::CheckTargetMergeState(LockedFile* lock, const std::
// 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,
// target. If we 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.
@ -1001,6 +1074,12 @@ UpdateState SnapshotManager::CheckTargetMergeState(LockedFile* lock, const std::
if (!QuerySnapshotStatus(name, &target_type, &status)) {
return UpdateState::MergeFailed;
}
if (target_type == "snapshot" &&
DecideMergePhase(snapshot_status) == MergePhase::SECOND_PHASE &&
update_status.merge_phase() == MergePhase::FIRST_PHASE) {
// The snapshot is not being merged because it's in the wrong phase.
return UpdateState::None;
}
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
@ -1036,6 +1115,38 @@ UpdateState SnapshotManager::CheckTargetMergeState(LockedFile* lock, const std::
return UpdateState::MergeCompleted;
}
bool SnapshotManager::MergeSecondPhaseSnapshots(LockedFile* lock) {
std::vector<std::string> snapshots;
if (!ListSnapshots(lock, &snapshots)) {
return UpdateState::MergeFailed;
}
SnapshotUpdateStatus update_status = ReadSnapshotUpdateStatus(lock);
CHECK(update_status.state() == UpdateState::Merging);
CHECK(update_status.merge_phase() == MergePhase::FIRST_PHASE);
update_status.set_merge_phase(MergePhase::SECOND_PHASE);
if (!WriteSnapshotUpdateStatus(lock, update_status)) {
return false;
}
bool rewrote_all = true;
for (const auto& snapshot : snapshots) {
SnapshotStatus snapshot_status;
if (!ReadSnapshotStatus(lock, snapshot, &snapshot_status)) {
return UpdateState::MergeFailed;
}
if (DecideMergePhase(snapshot_status) != MergePhase::SECOND_PHASE) {
continue;
}
if (!SwitchSnapshotToMerge(lock, snapshot)) {
LOG(ERROR) << "Failed to switch snapshot to a second-phase merge target: " << snapshot;
rewrote_all = false;
}
}
return rewrote_all;
}
std::string SnapshotManager::GetSnapshotBootIndicatorPath() {
return metadata_dir_ + "/" + android::base::Basename(kBootIndicatorPath);
}
@ -1048,6 +1159,10 @@ std::string SnapshotManager::GetForwardMergeIndicatorPath() {
return metadata_dir_ + "/allow-forward-merge";
}
std::string SnapshotManager::GetOldPartitionMetadataPath() {
return metadata_dir_ + "/old-partition-metadata";
}
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
@ -1172,6 +1287,10 @@ bool SnapshotManager::CollapseSnapshotDevice(const std::string& name,
if (!dm.DeleteDeviceIfExists(base_name)) {
LOG(ERROR) << "Unable to delete base device for snapshot: " << base_name;
}
auto source_name = GetSourceDeviceName(name);
if (!dm.DeleteDeviceIfExists(source_name)) {
LOG(ERROR) << "Unable to delete source device for snapshot: " << source_name;
}
return true;
}
@ -1274,9 +1393,9 @@ bool SnapshotManager::PerformInitTransition(InitTransition transition,
continue;
}
std::string backing_device;
if (!dm.GetDmDevicePathByName(GetBaseDeviceName(snapshot), &backing_device)) {
LOG(ERROR) << "Could not get device path for " << GetBaseDeviceName(snapshot);
std::string source_device;
if (!dm.GetDmDevicePathByName(GetSourceDeviceName(snapshot), &source_device)) {
LOG(ERROR) << "Could not get device path for " << GetSourceDeviceName(snapshot);
continue;
}
@ -1302,7 +1421,7 @@ bool SnapshotManager::PerformInitTransition(InitTransition transition,
}
if (transition == InitTransition::SELINUX_DETACH) {
auto message = misc_name + "," + cow_image_device + "," + backing_device;
auto message = misc_name + "," + cow_image_device + "," + source_device;
snapuserd_argv->emplace_back(std::move(message));
// Do not attempt to connect to the new snapuserd yet, it hasn't
@ -1313,7 +1432,7 @@ bool SnapshotManager::PerformInitTransition(InitTransition transition,
}
uint64_t base_sectors =
snapuserd_client_->InitDmUserCow(misc_name, cow_image_device, backing_device);
snapuserd_client_->InitDmUserCow(misc_name, cow_image_device, source_device);
if (base_sectors == 0) {
// Unrecoverable as metadata reads from cow device failed
LOG(FATAL) << "Failed to retrieve base_sectors from Snapuserd";
@ -1822,24 +1941,35 @@ bool SnapshotManager::MapPartitionWithSnapshot(LockedFile* lock,
}
if (live_snapshot_status->compression_enabled()) {
auto name = GetDmUserCowName(params.GetPartitionName());
// Get the source device (eg the view of the partition from before it was resized).
std::string source_device_path;
if (!MapSourceDevice(lock, params.GetPartitionName(), remaining_time,
&source_device_path)) {
LOG(ERROR) << "Could not map source device for: " << cow_name;
return false;
}
auto source_device = GetSourceDeviceName(params.GetPartitionName());
created_devices.EmplaceBack<AutoUnmapDevice>(&dm, source_device);
if (!WaitForDevice(source_device_path, remaining_time)) {
return false;
}
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;
}
auto name = GetDmUserCowName(params.GetPartitionName());
std::string new_cow_device;
if (!MapDmUserCow(lock, name, cow_path, base_path, remaining_time, &new_cow_device)) {
if (!MapDmUserCow(lock, name, cow_path, source_device_path, remaining_time,
&new_cow_device)) {
LOG(ERROR) << "Could not map dm-user device for partition "
<< params.GetPartitionName();
return false;
@ -1883,12 +2013,18 @@ bool SnapshotManager::UnmapPartitionWithSnapshot(LockedFile* lock,
}
auto& dm = DeviceMapper::Instance();
std::string base_name = GetBaseDeviceName(target_partition_name);
auto base_name = GetBaseDeviceName(target_partition_name);
if (!dm.DeleteDeviceIfExists(base_name)) {
LOG(ERROR) << "Cannot delete base device: " << base_name;
return false;
}
auto source_name = GetSourceDeviceName(target_partition_name);
if (!dm.DeleteDeviceIfExists(source_name)) {
LOG(ERROR) << "Cannot delete source device: " << source_name;
return false;
}
LOG(INFO) << "Successfully unmapped snapshot " << target_partition_name;
return true;
@ -2480,6 +2616,24 @@ Return SnapshotManager::CreateUpdateSnapshots(const DeltaArchiveManifest& manife
return Return::Error();
}
// If compression is enabled, we need to retain a copy of the old metadata
// so we can access original blocks in case they are moved around. We do
// not want to rely on the old super metadata slot because we don't
// guarantee its validity after the slot switch is successful.
if (cow_creator.compression_enabled) {
auto metadata = current_metadata->Export();
if (!metadata) {
LOG(ERROR) << "Could not export current metadata";
return Return::Error();
}
auto path = GetOldPartitionMetadataPath();
if (!android::fs_mgr::WriteToImageFile(path, *metadata.get())) {
LOG(ERROR) << "Cannot write old metadata to " << path;
return Return::Error();
}
}
SnapshotUpdateStatus status = {};
status.set_state(update_state);
status.set_compression_enabled(cow_creator.compression_enabled);
@ -2580,6 +2734,15 @@ Return SnapshotManager::CreateUpdateSnapshotsInternal(
continue;
}
// Find the original partition size.
auto name = target_partition->name();
auto old_partition_name =
name.substr(0, name.size() - target_suffix.size()) + cow_creator->current_suffix;
auto old_partition = cow_creator->current_metadata->FindPartition(old_partition_name);
if (old_partition) {
cow_creator_ret->snapshot_status.set_old_partition_size(old_partition->size());
}
// Store these device sizes to snapshot status file.
if (!CreateSnapshot(lock, &cow_creator_ret->snapshot_status)) {
return Return::Error();
@ -3267,5 +3430,26 @@ bool SnapshotManager::PerformSecondStageInitTransition() {
return PerformInitTransition(InitTransition::SECOND_STAGE);
}
const LpMetadata* SnapshotManager::ReadOldPartitionMetadata(LockedFile* lock) {
CHECK(lock);
if (!old_partition_metadata_) {
auto path = GetOldPartitionMetadataPath();
old_partition_metadata_ = android::fs_mgr::ReadFromImageFile(path);
if (!old_partition_metadata_) {
LOG(ERROR) << "Could not read old partition metadata from " << path;
return nullptr;
}
}
return old_partition_metadata_.get();
}
MergePhase SnapshotManager::DecideMergePhase(const SnapshotStatus& status) {
if (status.compression_enabled() && status.device_size() < status.old_partition_size()) {
return MergePhase::FIRST_PHASE;
}
return MergePhase::SECOND_PHASE;
}
} // namespace snapshot
} // namespace android

3
fs_mgr/libsnapshot/snapshot_test.cpp
View File

@ -234,7 +234,8 @@ class SnapshotTest : public ::testing::Test {
.partition_opener = &opener,
};
auto result = sm->OpenSnapshotWriter(params, {});
auto old_partition = "/dev/block/mapper/" + GetOtherPartitionName(name);
auto result = sm->OpenSnapshotWriter(params, {old_partition});
if (!result) {
return AssertionFailure() << "Cannot open snapshot for writing: " << name;
}

8
fs_mgr/libsnapshot/utility.cpp
View File

@ -187,5 +187,13 @@ bool IsCompressionEnabled() {
return android::base::GetBoolProperty("ro.virtual_ab.compression.enabled", false);
}
std::string GetOtherPartitionName(const std::string& name) {
auto suffix = android::fs_mgr::GetPartitionSlotSuffix(name);
CHECK(suffix == "_a" || suffix == "_b");
auto other_suffix = (suffix == "_a") ? "_b" : "_a";
return name.substr(0, name.size() - suffix.size()) + other_suffix;
}
} // namespace snapshot
} // namespace android

3
fs_mgr/libsnapshot/utility.h
View File

@ -131,5 +131,8 @@ void AppendExtent(google::protobuf::RepeatedPtrField<chromeos_update_engine::Ext
bool IsCompressionEnabled();
// Swap the suffix of a partition name.
std::string GetOtherPartitionName(const std::string& name);
} // namespace snapshot
} // namespace android