[PATCH] Make ->buflen == 0 on SYNC io_u's

It eases the error handling in the splice and sync io engine.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/io_u.c b/io_u.c
index 738f3e2..45e8bb8 100644
--- a/io_u.c
+++ b/io_u.c
@@ -229,6 +229,7 @@
 	if (!queue_full(td)) {
 		io_u = list_entry(td->io_u_freelist.next, struct io_u, list);
 
+		io_u->buflen = 0;
 		io_u->error = 0;
 		io_u->resid = 0;
 		list_del(&io_u->list);