perf: use io copy with buffer pool (#6389)

* feat: add io methods with buffer

* chore: move io.Copy calls to utils.CopyWithBuffer

drivers/thunder/util.go

@@ -190,7 +190,7 @@ func getGcid(r io.Reader, size int64) (string, error) {
 	readSize := calcBlockSize(size)
 	for {
 		hash2.Reset()
-		if n, err := io.CopyN(hash2, r, readSize); err != nil && n == 0 {
+		if n, err := utils.CopyWithBufferN(hash2, r, readSize); err != nil && n == 0 {
 			if err != io.EOF {
 				return "", err
 			}