[PATCH] elevator: introduce a way to reuse rq for internal FIFO handling
The io schedulers can use this instead of having to allocate space for
it themselves.
Signed-off-by: Jens Axboe <axboe@suse.de>
diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index 95b2a04..0e7b1a7 100644
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -166,4 +166,16 @@
#define rq_end_sector(rq) ((rq)->sector + (rq)->nr_sectors)
#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
+/*
+ * Hack to reuse the donelist list_head as the fifo time holder while
+ * the request is in the io scheduler. Saves an unsigned long in rq.
+ */
+#define rq_fifo_time(rq) ((unsigned long) (rq)->donelist.next)
+#define rq_set_fifo_time(rq,exp) ((rq)->donelist.next = (void *) (exp))
+#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
+#define rq_fifo_clear(rq) do { \
+ list_del_init(&(rq)->queuelist); \
+ INIT_LIST_HEAD(&(rq)->donelist); \
+ } while (0)
+
#endif