Initial commit for TRIM/DISCARD support

Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
diff --git a/engines/splice.c b/engines/splice.c
index e9b6aad..427b4e5 100644
--- a/engines/splice.c
+++ b/engines/splice.c
@@ -223,6 +223,8 @@
 			ret = fio_splice_read_old(td, io_u);
 	} else if (io_u->ddir == DDIR_WRITE)
 		ret = fio_splice_write(td, io_u);
+	else if (io_u->ddir == DDIR_TRIM)
+		ret = do_io_u_trim(td, io_u);
 	else
 		ret = do_io_u_sync(td, io_u);