test/fsync: error out if we submit less than we wanted

This failure is expected on kernels that don't support the DRAIN
primitive.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

test/fsync.c

@@ -95,7 +95,10 @@ static int test_barrier_fsync(struct io_uring *ring)
 	sqe->flags = IOSQE_IO_DRAIN;
 
 	ret = io_uring_submit(ring);
-	if (ret <= 0) {
+	if (ret < 5) {
+		printf("Submitted only %d\n", ret);
+		goto err;
+	} else if (ret < 0) {
 		printf("sqe submit failed\n");
 		if (ret == EINVAL)
 			printf("kernel may not support barrier fsync yet\n");