ResetStatus deletes snapshots for VAB.

When ResetStatus() is called, delete snapshots to free up space on
VAB devices.

On regular A/B, there is no need to cancel the update completely so that
the update may be resumed next time. However, on VAB devices, a
cancelled update should not occupy previously allocated space.

Test: manually call update_engine_client --cancel when an update is in progress, then
      call update_engine_client --reset_status, then
      call snapshotctl dump to check that snapshots are deleted.
      Then, re-apply the update.

Test: manually kill update_engine when an update is in progress, then
      call update_engine_client --reset_status, then
      call snapshotctl dump to check that snapshots are deleted.
      Then, re-apply the update.

Test: manually apply an update until UPDATED_NEED_REBOOT, then
      call update_engine_client --reset_status, then
      call snapshotctl dump to check that snapshots are deleted.
      Then, re-apply the update.

Test: manually apply an update until UPDATED_NEED_REBOOT, then
      kill update_engine, then
      call update_engine_client --reset_status, then
      call snapshotctl dump to check that snapshots are deleted.
      Then, re-apply the update.

Bug: 147696014

Change-Id: Ic7049772091a34e0e666fd7ae361ef474d5a28aa
Merged-In: Ic7049772091a34e0e666fd7ae361ef474d5a28aa

1 files changed, 16 insertions, 0 deletions

diff --git a/common/dynamic_partition_control_interface.h b/common/dynamic_partition_control_interface.h
index a878f2e9..d5db9bcd 100644
--- a/common/dynamic_partition_control_interface.h
+++ b/common/dynamic_partition_control_interface.h
@@ -98,10 +98,26 @@ class DynamicPartitionControlInterface {
   // - If any error, but caller should retry after reboot, action completes with
   //   kError.
   // - If any irrecoverable failures, action completes with kDeviceCorrupted.
+  //
+  // See ResetUpdate for differences between CleanuPreviousUpdateAction and
+  // ResetUpdate.
   virtual std::unique_ptr<AbstractAction> GetCleanupPreviousUpdateAction(
       BootControlInterface* boot_control,
       PrefsInterface* prefs,
       CleanupPreviousUpdateActionDelegateInterface* delegate) = 0;
+
+  // Called after an unwanted payload has been successfully applied and the
+  // device has not yet been rebooted.
+  //
+  // For snapshot updates (Virtual A/B), it calls
+  // DeltaPerformer::ResetUpdateProgress(false /* quick */) and
+  // frees previously allocated space; the next update will need to be
+  // started over.
+  //
+  // Note: CleanupPreviousUpdateAction does not do anything if an update is in
+  // progress, while ResetUpdate() forcefully free previously
+  // allocated space for snapshot updates.
+  virtual bool ResetUpdate(PrefsInterface* prefs) = 0;
 };
 
 }  // namespace chromeos_update_engine