add logs

add logs for https://github.com/chrislusf/seaweedfs/issues/1064

weed/s3api/filer_util.go

@@ -89,6 +89,7 @@ func (s3a *S3ApiServer) list(ctx context.Context, parentDirectoryPath, prefix, s
 		glog.V(4).Infof("read directory: %v", request)
 		resp, err := client.ListEntries(ctx, request)
 		if err != nil {
+			glog.V(0).Infof("read directory %v: %v", request, err)
 			return fmt.Errorf("list dir %v: %v", parentDirectoryPath, err)
 		}