[PATCH] Document ->queue() in the skeleton engine
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/engines/skeleton_external.c b/engines/skeleton_external.c
index 2c330f0..785b9a6 100644
--- a/engines/skeleton_external.c
+++ b/engines/skeleton_external.c
@@ -57,6 +57,12 @@
* The ->queue() hook is responsible for initiating io on the io_u
* being passed in. If the io engine is a synchronous one, io may complete
* before ->queue() returns. Required.
+ *
+ * The io engine must transfer in the direction noted by io_u->ddir
+ * to the buffer pointed to by io_u->xfer_buf for as many bytes as
+ * io_u->xfer_buflen. Residual data count may be set in io_u->residual
+ * for a short read/write. Should return 0 for io_u complete, < 0 for
+ * an error, and > 0 for the number of bytes transferred.
*/
static int fio_skeleton_queue(struct thread_data *td, struct io_u *io_u)
{