this works great and support long file names

weed/filer2/abstract_sql/hashing.go

@@ -0,0 +1,13 @@
+package abstract_sql
+
+import (
+	"crypto/md5"
+	"io"
+)
+
+// returns a 128 bit hash
+func md5hash(dir string) []byte {
+	h := md5.New()
+	io.WriteString(h, dir)
+	return h.Sum(nil)
+}