block: Add support for reinsert a dispatched req
Add support for reinserting a dispatched request back to the
scheduler's internal data structures.
This capability is used by the device driver when it chooses to
interrupt the current request transmission and execute another (more
urgent) pending request. For example: interrupting long write in order
to handle pending read. The device driver re-inserts the
remaining write request back to the scheduler, to be rescheduled
for transmission later on.
Add API for verifying whether the current scheduler
supports reinserting requests mechanism. If reinsert mechanism isn't
supported by the scheduler, this code path will never be activated.
Change-Id: I5c982a66b651ebf544aae60063ac8a340d79e67f
Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index 7d4e035..c07b63b 100644
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -22,6 +22,8 @@
typedef int (elevator_dispatch_fn) (struct request_queue *, int);
typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
+typedef int (elevator_reinsert_req_fn) (struct request_queue *,
+ struct request *);
typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
typedef int (elevator_may_queue_fn) (struct request_queue *, int);
@@ -46,6 +48,8 @@
elevator_dispatch_fn *elevator_dispatch_fn;
elevator_add_req_fn *elevator_add_req_fn;
+ elevator_reinsert_req_fn *elevator_reinsert_req_fn;
+
elevator_activate_req_fn *elevator_activate_req_fn;
elevator_deactivate_req_fn *elevator_deactivate_req_fn;
@@ -122,6 +126,7 @@
extern void elv_bio_merged(struct request_queue *q, struct request *,
struct bio *);
extern void elv_requeue_request(struct request_queue *, struct request *);
+extern int elv_reinsert_request(struct request_queue *, struct request *);
extern struct request *elv_former_request(struct request_queue *, struct request *);
extern struct request *elv_latter_request(struct request_queue *, struct request *);
extern int elv_register_queue(struct request_queue *q);