[PATCH] ->queue() error handling

We return 1/0 for failure/success and put the error in io_u->error.
The libaio engine didn't quite do that.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/engines/fio-engine-libaio.c b/engines/fio-engine-libaio.c
index 5e394e3..daee659 100644
--- a/engines/fio-engine-libaio.c
+++ b/engines/fio-engine-libaio.c
@@ -78,9 +78,13 @@
 			break;
 	} while (1);
 
-	assert(ret);
+	if (ret <= 0) {
+		io_u->resid = io_u->buflen;
+		io_u->error = -ret;
+		return 1;
+	}
 
-	return (int) -ret;
+	return 0;
 }
 
 static int fio_libaio_cancel(struct thread_data *td, struct io_u *io_u)