xl: Fix ReadFile to keep the order always for reading the data back. (#1339)

Also fixes a stackoverflow bug in namespace locking.

object-api-multipart.go

@@ -297,6 +297,9 @@ func (o objectAPI) NewMultipartUpload(bucket, object string) (string, *probe.Err
 			// uploadIDPath doesn't exist, so create empty file to reserve the name
 			var w io.WriteCloser
 			if w, e = o.storage.CreateFile(minioMetaVolume, uploadIDPath); e == nil {
+				// Just write some data for erasure code, rather than zero bytes.
+				w.Write([]byte(uploadID))
+				// Close the writer.
 				if e = w.Close(); e != nil {
 					return "", probe.NewError(e)
 				}