Merge changes from topic "snapuserd-enable-read-ahead"

* changes:
  libsnapshot: snapuserd: Enable read-ahead functionality
  libsnapshot: Bump up the kCowVersionManifest version
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h b/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h
index c05b7ef..000e5e1 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h
@@ -24,7 +24,7 @@
 static constexpr uint32_t kCowVersionMajor = 2;
 static constexpr uint32_t kCowVersionMinor = 0;
 
-static constexpr uint32_t kCowVersionManifest = 1;
+static constexpr uint32_t kCowVersionManifest = 2;
 
 static constexpr uint32_t BLOCK_SZ = 4096;
 static constexpr uint32_t BLOCK_SHIFT = (__builtin_ffs(BLOCK_SZ) - 1);
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h b/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h
index 1192e7d..f43ea68 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h
@@ -37,7 +37,7 @@
     // Number of CowOperations in a cluster. 0 for no clustering. Cannot be 1.
     uint32_t cluster_ops = 200;
 
-    bool scratch_space = false;
+    bool scratch_space = true;
 };
 
 // Interface for writing to a snapuserd COW. All operations are ordered; merges