crimson/os/seastore/linked_tree_node: set reserved_ptr to an 8-byte

aligned address

Maybe we shouldn't be using an instant integer as the invalid pointer.

Fixes: https://tracker.ceph.com/issues/70202
Signed-off-by: Xuehan Xu <[email protected]>

Author: xxhdx1985126

src/crimson/os/seastore/linked_tree_node.h

@@ -217,7 +217,10 @@ class BaseChildNode {
 // indirect mapping.
 template <typename T, typename node_key_t>
 inline BaseChildNode<T, node_key_t>* get_reserved_ptr() {
-  return (BaseChildNode<T, node_key_t>*)0x1;
+  //TODO: using instant integers as invalid pointers may
+  //	  not be a good practice.
+  constexpr uint64_t reserved_ptr = std::numeric_limits<size_t>::max() - 15;
+  return (BaseChildNode<T, node_key_t>*)reserved_ptr;
 }
 
 template <typename T, typename node_key_t>