4 #include <linux/blkdev.h>
5 #include <linux/elevator.h>
7 #include <linux/module.h>
8 #include <linux/init.h>
11 * See if we can find a request that this buffer can be coalesced with.
13 static int elevator_noop_merge(request_queue_t *q, struct request **req,
18 ret = elv_try_last_merge(q, bio);
19 if (ret != ELEVATOR_NO_MERGE)
25 static void elevator_noop_merge_requests(request_queue_t *q, struct request *req,
28 list_del_init(&next->queuelist);
31 static void elevator_noop_add_request(request_queue_t *q, struct request *rq)
33 elv_dispatch_add_tail(q, rq);
36 * new merges must not precede this barrier
38 if (rq->flags & REQ_HARDBARRIER)
40 else if (!q->last_merge)
44 static int elevator_noop_dispatch(request_queue_t *q, int force)
49 static struct elevator_type elevator_noop = {
51 .elevator_merge_fn = elevator_noop_merge,
52 .elevator_merge_req_fn = elevator_noop_merge_requests,
53 .elevator_dispatch_fn = elevator_noop_dispatch,
54 .elevator_add_req_fn = elevator_noop_add_request,
56 .elevator_name = "noop",
57 .elevator_owner = THIS_MODULE,
60 static int __init noop_init(void)
62 return elv_register(&elevator_noop);
65 static void __exit noop_exit(void)
67 elv_unregister(&elevator_noop);
70 module_init(noop_init);
71 module_exit(noop_exit);
74 MODULE_AUTHOR("Jens Axboe");
75 MODULE_LICENSE("GPL");
76 MODULE_DESCRIPTION("No-op IO scheduler");