iolog: fix Null pointer dereferences (FORWARD_NULL)

CID 494150: Null pointer dereferences (FORWARD_NULL) @ iolog.c:148 in ipo_special()
This patch removes the possibility of null pointer dereferencing(io_u->file)
throughout the call stack of get_io_u() → read_iolog_get() → dp_fill_dspec_data()

Signed-off-by: Hyunwoo Park <dshw.park@samsung.com>

iolog.c

@@ -236,15 +236,15 @@ int read_iolog_get(struct thread_data *td, struct io_u *io_u)
 						io_u->buflen, io_u->file->file_name);
 			if (ipo->delay)
 				iolog_delay(td, ipo->delay);
+
+			if (td->o.dp_type != FIO_DP_NONE)
+				dp_fill_dspec_data(td, io_u);
 		} else {
 			elapsed = mtime_since_genesis();
 			if (ipo->delay > elapsed)
 				usec_sleep(td, (ipo->delay - elapsed) * 1000);
 		}
 
-		if (td->o.dp_type != FIO_DP_NONE)
-			dp_fill_dspec_data(td, io_u);
-
 		free(ipo);
 
 		if (io_u->ddir != DDIR_WAIT)