[Kernel] Fix data race on XFile position

src/xenia/kernel/xfile.cc

@@ -35,6 +35,16 @@ XFile::~XFile() {
   file_->Destroy();
 }
 
+uint64_t XFile::position() const {
+  std::lock_guard<std::mutex> lock(file_lock_);
+  return position_;
+}
+
+void XFile::set_position(uint64_t value) {
+  std::lock_guard<std::mutex> lock(file_lock_);
+  position_ = value;
+}
+
 X_STATUS XFile::QueryDirectory(X_FILE_DIRECTORY_INFORMATION* out_info,
                                size_t length, const std::string_view file_name,
                                bool restart) {

src/xenia/kernel/xfile.h

@@ -143,8 +143,8 @@ class XFile : public XObject {
   const std::string& path() const { return file_->entry()->path(); }
   const std::string& name() const { return file_->entry()->name(); }
 
-  uint64_t position() const { return position_; }
+  uint64_t position() const;
-  void set_position(uint64_t value) { position_ = value; }
+  void set_position(uint64_t value);
 
   X_STATUS QueryDirectory(X_FILE_DIRECTORY_INFORMATION* out_info, size_t length,
                           const std::string_view file_name, bool restart);
@@ -193,7 +193,7 @@ class XFile : public XObject {
   vfs::File* file_ = nullptr;
   std::unique_ptr<threading::Event> async_event_ = nullptr;
 
-  std::mutex file_lock_;
+  mutable std::mutex file_lock_;
   std::mutex completion_port_lock_;
   std::vector<std::pair<uint32_t, object_ref<XIOCompletion>>> completion_ports_;