update_engine resize dynamic partitions during OTA.

update_engine uses device mapper to resize dynamic partitions
before opening the devices to apply the update.

* DeltaPerformer calls BootControlInterface::InitPartitionMetadata
  when parsing the update manifest. The implementation for
  BootControlAndroid::InitPartitionMetadata does the following
  if sizes for dynamic partitions are incorrect (assuming updating
  from slot A to B):
  * Load metadata from metadata slot A
  * Delete all extents of partitions at slot B (with _b suffix)
  * Add extents for partitions at slot B
  * Write metadata to metadata slot B
  * Re-map all partitions at slot B using metadata slot B with
    force_writable = true
* BootControlAndroid::GetPartitionDevice() checks device-mapper
  before returning static partitions.
* PostinstallRunnerAction::Cleanup calls BootControlInterface::Cleanup
  which unmaps all partitions at slot B.

A partition "foo" is considered dynamic if foo_a exists as a dynamic
partition OR foo_b does NOT exist as a static partition.

Bug: 110717529

Test: manual ota
Test: update_engine_unittests --gtest_filter=*BootControlAndroid*
Change-Id: I50f410b486a874242663624801c3694151bdda18

1 files changed, 13 insertions, 0 deletions

diff --git a/common/boot_control_interface.h b/common/boot_control_interface.h
index 659b3880..776333c8 100644
--- a/common/boot_control_interface.h
+++ b/common/boot_control_interface.h
@@ -18,6 +18,7 @@
 #define UPDATE_ENGINE_COMMON_BOOT_CONTROL_INTERFACE_H_
 
 #include <climits>
+#include <map>
 #include <string>
 
 #include <base/callback.h>
@@ -32,6 +33,7 @@ namespace chromeos_update_engine {
 class BootControlInterface {
  public:
   using Slot = unsigned int;
+  using PartitionSizes = std::map<std::string, uint64_t>;
 
   static const Slot kInvalidSlot = UINT_MAX;
 
@@ -77,6 +79,17 @@ class BootControlInterface {
   // of the operation.
   virtual bool MarkBootSuccessfulAsync(base::Callback<void(bool)> callback) = 0;
 
+  // Initialize metadata of underlying partitions for a given |slot|.
+  // Ensure that partitions at the specified |slot| has a given size, as
+  // specified by |partition_sizes|. |partition_sizes| has the format:
+  // {"vendor": 524288000, "system": 2097152000, ...}; values must be
+  // aligned to the logical block size of the super partition.
+  virtual bool InitPartitionMetadata(Slot slot,
+                                     const PartitionSizes& partition_sizes) = 0;
+
+  // Do necessary clean-up operations after the whole update.
+  virtual void Cleanup() = 0;
+
   // Return a human-readable slot name used for logging.
   static std::string SlotName(Slot slot) {
     if (slot == kInvalidSlot)