1 files changed, 80 insertions, 0 deletions
diff --git a/src/crimson/os/seastore/onode_manager/staged-fltree/node_extent_mutable.h b/src/crimson/os/seastore/onode_manager/staged-fltree/node_extent_mutable.h
new file mode 100644
index 000000000..52f10a013
--- /dev/null
+++ b/src/crimson/os/seastore/onode_manager/staged-fltree/node_extent_mutable.h
@@ -0,0 +1,80 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:nil -*-
+// vim: ts=8 sw=2 smarttab
+
+#include <cstring>
+
+#include "fwd.h"
+
+#pragma once
+
+namespace crimson::os::seastore::onode {
+
+class NodeExtent;
+
+/**
+ * NodeExtentMutable
+ *
+ * A thin wrapper of NodeExtent to make sure that only the newly allocated
+ * or the duplicated NodeExtent is mutable, and the memory modifications are
+ * safe within the extent range.
+ */
+class NodeExtentMutable {
+ public:
+  void copy_in_absolute(void* dst, const void* src, extent_len_t len) {
+    assert((char*)dst >= get_write());
+    assert((char*)dst + len <= buf_upper_bound());
+    std::memcpy(dst, src, len);
+  }
+  template <typename T>
+  void copy_in_absolute(void* dst, const T& src) {
+    copy_in_absolute(dst, &src, sizeof(T));
+  }
+
+  const void* copy_in_relative(
+      extent_len_t dst_offset, const void* src, extent_len_t len) {
+    auto dst = get_write() + dst_offset;
+    copy_in_absolute(dst, src, len);
+    return dst;
+  }
+  template <typename T>
+  const T* copy_in_relative(
+      extent_len_t dst_offset, const T& src) {
+    auto dst = copy_in_relative(dst_offset, &src, sizeof(T));
+    return static_cast<const T*>(dst);
+  }
+
+  void shift_absolute(const void* src, extent_len_t len, int offset) {
+    assert((const char*)src >= get_write());
+    assert((const char*)src + len <= buf_upper_bound());
+    char* to = (char*)src + offset;
+    assert(to >= get_write());
+    assert(to + len <= buf_upper_bound());
+    if (len != 0) {
+      std::memmove(to, src, len);
+    }
+  }
+  void shift_relative(extent_len_t src_offset, extent_len_t len, int offset) {
+    shift_absolute(get_write() + src_offset, len, offset);
+  }
+
+  template <typename T>
+  void validate_inplace_update(const T& updated) {
+    assert((const char*)&updated >= get_write());
+    assert((const char*)&updated + sizeof(T) <= buf_upper_bound());
+  }
+
+  const char* get_read() const;
+  char* get_write();
+  extent_len_t get_length() const;
+  laddr_t get_laddr() const;
+
+ private:
+  explicit NodeExtentMutable(NodeExtent&);
+  const char* buf_upper_bound() const;
+
+  NodeExtent& extent;
+
+  friend class NodeExtent;
+};
+
+}