[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 <[email protected]>
---
include/linux/elevator.h | 12 ++++++++++++
1 files changed, 12 insertions(+), 0 deletions(-)
diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index 38f0f0d..6e1c903 100644
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -167,4 +167,16 @@ enum {
#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
--
1.4.1.ged0e0
--
Jens Axboe
-
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