libsnapshot: Refactor CreateLogicalAndSnapshotPartitions
Create SnapshotManager::MapPartitionWithSnapshot that deals
with one partition so that the code can be re-used later.
Test: libsnapshot_test
Change-Id: Iba36e6c05f8541397323361f7ceb62a6472d2e1c
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h b/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
index 1f3828e..6f0e804 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
@@ -329,6 +329,10 @@
std::string GetSnapshotDeviceName(const std::string& snapshot_name,
const SnapshotStatus& status);
+ // Map the base device, COW devices, and snapshot device.
+ bool MapPartitionWithSnapshot(LockedFile* lock, CreateLogicalPartitionParams params,
+ std::string* path);
+
std::string gsid_dir_;
std::string metadata_dir_;
std::unique_ptr<IDeviceInfo> device_;
diff --git a/fs_mgr/libsnapshot/snapshot.cpp b/fs_mgr/libsnapshot/snapshot.cpp
index 7f37dc5..1f675d4 100644
--- a/fs_mgr/libsnapshot/snapshot.cpp
+++ b/fs_mgr/libsnapshot/snapshot.cpp
@@ -19,6 +19,7 @@
#include <sys/types.h>
#include <sys/unistd.h>
+#include <optional>
#include <thread>
#include <unordered_set>
@@ -1102,22 +1103,6 @@
auto lock = LockExclusive();
if (!lock) return false;
- std::vector<std::string> snapshot_list;
- if (!ListSnapshots(lock.get(), &snapshot_list)) {
- return false;
- }
-
- std::unordered_set<std::string> live_snapshots;
- for (const auto& snapshot : snapshot_list) {
- SnapshotStatus status;
- if (!ReadSnapshotStatus(lock.get(), snapshot, &status)) {
- return false;
- }
- if (status.state != SnapshotState::MergeCompleted) {
- live_snapshots.emplace(snapshot);
- }
- }
-
const auto& opener = device_->GetPartitionOpener();
uint32_t slot = SlotNumberForSlotSuffix(device_->GetSlotSuffix());
auto metadata = android::fs_mgr::ReadMetadata(opener, super_device, slot);
@@ -1126,59 +1111,102 @@
return false;
}
- // Map logical partitions.
- auto& dm = DeviceMapper::Instance();
for (const auto& partition : metadata->partitions) {
- auto partition_name = GetPartitionName(partition);
- if (!partition.num_extents) {
- LOG(INFO) << "Skipping zero-length logical partition: " << partition_name;
- continue;
- }
-
- if (!(partition.attributes & LP_PARTITION_ATTR_UPDATED)) {
- LOG(INFO) << "Detected re-flashing of partition, will skip snapshot: "
- << partition_name;
- live_snapshots.erase(partition_name);
- }
-
CreateLogicalPartitionParams params = {
.block_device = super_device,
.metadata = metadata.get(),
.partition = &partition,
.partition_opener = &opener,
};
-
- if (auto iter = live_snapshots.find(partition_name); iter != live_snapshots.end()) {
- // If the device has a snapshot, it'll need to be writable, and
- // we'll need to create the logical partition with a marked-up name
- // (since the snapshot will use the partition name).
- params.force_writable = true;
- params.device_name = GetBaseDeviceName(partition_name);
- }
-
std::string ignore_path;
- if (!CreateLogicalPartition(params, &ignore_path)) {
- LOG(ERROR) << "Could not create logical partition " << partition_name << " as device "
- << params.GetDeviceName();
- return false;
- }
- if (!params.force_writable) {
- // No snapshot.
- continue;
- }
-
- // 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;
- }
- if (!MapSnapshot(lock.get(), partition_name, base_device, {}, &ignore_path)) {
- LOG(ERROR) << "Could not map snapshot for partition: " << partition_name;
+ if (!MapPartitionWithSnapshot(lock.get(), std::move(params), &ignore_path)) {
return false;
}
}
+
+ LOG(INFO) << "Created logical partitions with snapshot.";
+ return true;
+}
+
+bool SnapshotManager::MapPartitionWithSnapshot(LockedFile* lock,
+ CreateLogicalPartitionParams params,
+ std::string* path) {
+ CHECK(lock);
+ path->clear();
+
+ // Fill out fields in CreateLogicalPartitionParams so that we have more information (e.g. by
+ // reading super partition metadata).
+ CreateLogicalPartitionParams::OwnedData params_owned_data;
+ if (!params.InitDefaults(¶ms_owned_data)) {
+ return false;
+ }
+
+ if (!params.partition->num_extents) {
+ LOG(INFO) << "Skipping zero-length logical partition: " << params.GetPartitionName();
+ return true; // leave path empty to indicate that nothing is mapped.
+ }
+
+ // Determine if there is a live snapshot for the SnapshotStatus of the partition; i.e. if the
+ // partition still has a snapshot that needs to be mapped. If no live snapshot or merge
+ // completed, live_snapshot_status is set to nullopt.
+ std::optional<SnapshotStatus> live_snapshot_status;
+ do {
+ if (!(params.partition->attributes & LP_PARTITION_ATTR_UPDATED)) {
+ LOG(INFO) << "Detected re-flashing of partition, will skip snapshot: "
+ << params.GetPartitionName();
+ break;
+ }
+ auto file_path = GetSnapshotStatusFilePath(params.GetPartitionName());
+ if (access(file_path.c_str(), F_OK) != 0) {
+ if (errno != ENOENT) {
+ PLOG(INFO) << "Can't map snapshot for " << params.GetPartitionName()
+ << ": Can't access " << file_path;
+ return false;
+ }
+ break;
+ }
+ live_snapshot_status = std::make_optional<SnapshotStatus>();
+ if (!ReadSnapshotStatus(lock, params.GetPartitionName(), &*live_snapshot_status)) {
+ return false;
+ }
+ // No live snapshot if merge is completed.
+ if (live_snapshot_status->state == SnapshotState::MergeCompleted) {
+ live_snapshot_status.reset();
+ }
+ } while (0);
+
+ if (live_snapshot_status.has_value()) {
+ // dm-snapshot requires the base device to be writable.
+ params.force_writable = true;
+ // Map the base device with a different name to avoid collision.
+ params.device_name = GetBaseDeviceName(params.GetPartitionName());
+ }
+
+ auto& dm = DeviceMapper::Instance();
+ std::string ignore_path;
+ if (!CreateLogicalPartition(params, &ignore_path)) {
+ LOG(ERROR) << "Could not create logical partition " << params.GetPartitionName()
+ << " as device " << params.GetDeviceName();
+ return false;
+ }
+ if (!live_snapshot_status.has_value()) {
+ 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;
+ }
+ if (!MapSnapshot(lock, params.GetPartitionName(), base_device, {}, path)) {
+ LOG(ERROR) << "Could not map snapshot for partition: " << params.GetPartitionName();
+ return false;
+ }
+
+ LOG(INFO) << "Mapped " << params.GetPartitionName() << " as snapshot device at " << *path;
+
return true;
}