avoid additional serialize call

pageserver/src/layered_repository/delta_layer.rs

@@ -672,6 +672,25 @@ impl DeltaLayerWriter {
         Ok(())
     }
 
+    pub fn put_value_bytes(
+        &mut self,
+        key: Key,
+        lsn: Lsn,
+        val: &[u8],
+        will_init: bool,
+    ) -> Result<()> {
+        assert!(self.lsn_range.start <= lsn);
+
+        let off = self.blob_writer.write_blob(val)?;
+
+        let blob_ref = BlobRef::new(off, will_init);
+
+        let delta_key = DeltaKey::from_key_lsn(&key, lsn);
+        self.tree.append(&delta_key.0, blob_ref.0)?;
+
+        Ok(())
+    }
+
     pub fn size(&self) -> u64 {
         self.blob_writer.size() + self.tree.borrow_writer().size()
     }

pageserver/src/layered_repository/inmemory_layer.rs

@@ -352,8 +352,8 @@ impl InMemoryLayer {
             // Write all page versions
             for (lsn, pos) in vec_map.as_slice() {
                 cursor.read_blob_into_buf(*pos, &mut buf)?;
-                let val = Value::des(&buf)?;
-                delta_layer_writer.put_value(key, *lsn, val)?;
+                let will_init = Value::des(&buf)?.will_init();
+                delta_layer_writer.put_value_bytes(key, *lsn, &buf, will_init)?;
             }
         }