Index: library/mongodb/nsfmongo.c
===================================================================
diff -u -r24571ae44c492c681d3efd2f2d2f5169ad7d6d57 -r919f731adf8e0104d8addfec4540159fba75ed81
--- library/mongodb/nsfmongo.c	(.../nsfmongo.c)	(revision 24571ae44c492c681d3efd2f2d2f5169ad7d6d57)
+++ library/mongodb/nsfmongo.c	(.../nsfmongo.c)	(revision 919f731adf8e0104d8addfec4540159fba75ed81)
@@ -1364,6 +1364,9 @@
       if (n > 0) {
 	iov.iov_len = n;
 	n = mongoc_gridfs_file_writev(gridFile, &iov, 1, 0);
+        if (n != iov.iov_len) {
+          NsfLog(interp, NSF_LOG_WARN, "mongodb: write of %d bytes returned %d", iov.iov_len, n);
+        }
       } else if (n == 0) {
 	break;
       } else {