diff --git a/common/dynamic_partition_control_interface.h b/common/dynamic_partition_control_interface.h
index da27932..d5e1d8d 100644
--- a/common/dynamic_partition_control_interface.h
+++ b/common/dynamic_partition_control_interface.h
@@ -165,7 +165,9 @@
       const std::string& unsuffixed_partition_name,
       const std::optional<std::string>&,
       bool is_append = false) = 0;
-  virtual FileDescriptorPtr OpenCowReader(
+  // Open a general purpose FD capable to reading and writing to COW. Note that
+  // writes must be block aligned.
+  virtual FileDescriptorPtr OpenCowFd(
       const std::string& unsuffixed_partition_name,
       const std::optional<std::string>&,
       bool is_append = false) = 0;
diff --git a/common/dynamic_partition_control_stub.cc b/common/dynamic_partition_control_stub.cc
index 05803fe..dd30a8b 100644
--- a/common/dynamic_partition_control_stub.cc
+++ b/common/dynamic_partition_control_stub.cc
@@ -98,13 +98,6 @@
   return nullptr;
 }
 
-FileDescriptorPtr DynamicPartitionControlStub::OpenCowReader(
-    const std::string& unsuffixed_partition_name,
-    const std::optional<std::string>&,
-    bool /*is_append */) {
-  return nullptr;
-}
-
 bool DynamicPartitionControlStub::MapAllPartitions() {
   return false;
 }
diff --git a/common/dynamic_partition_control_stub.h b/common/dynamic_partition_control_stub.h
index eb7154c..515ec7c 100644
--- a/common/dynamic_partition_control_stub.h
+++ b/common/dynamic_partition_control_stub.h
@@ -64,9 +64,12 @@
       const std::string& unsuffixed_partition_name,
       const std::optional<std::string>&,
       bool is_append) override;
-  FileDescriptorPtr OpenCowReader(const std::string& unsuffixed_partition_name,
-                                  const std::optional<std::string>&,
-                                  bool is_append = false) override;
+
+  FileDescriptorPtr OpenCowFd(const std::string& unsuffixed_partition_name,
+                              const std::optional<std::string>&,
+                              bool is_append = false) override {
+    return nullptr;
+  }
 
   bool MapAllPartitions() override;
   bool UnmapAllPartitions() override;
diff --git a/common/mock_dynamic_partition_control.h b/common/mock_dynamic_partition_control.h
index 391d3eb..bfd1b0c 100644
--- a/common/mock_dynamic_partition_control.h
+++ b/common/mock_dynamic_partition_control.h
@@ -37,7 +37,7 @@
   MOCK_METHOD(FeatureFlag, GetVirtualAbFeatureFlag, (), (override));
   MOCK_METHOD(bool, FinishUpdate, (bool), (override));
   MOCK_METHOD(FileDescriptorPtr,
-              OpenCowReader,
+              OpenCowFd,
               (const std::string& unsuffixed_partition_name,
                const std::optional<std::string>& source_path,
                bool is_append),