diff options
Diffstat (limited to 'block/noop-iosched.c')
-rw-r--r-- | block/noop-iosched.c | 119 |
1 files changed, 119 insertions, 0 deletions
diff --git a/block/noop-iosched.c b/block/noop-iosched.c new file mode 100644 index 00000000000..f370e4a7fe6 --- /dev/null +++ b/block/noop-iosched.c @@ -0,0 +1,119 @@ +/* + * elevator noop + */ +#include <linux/blkdev.h> +#include <linux/elevator.h> +#include <linux/bio.h> +#include <linux/module.h> +#include <linux/init.h> + +struct noop_data { + struct list_head queue; +}; + +static void noop_merged_requests(request_queue_t *q, struct request *rq, + struct request *next) +{ + list_del_init(&next->queuelist); +} + +static int noop_dispatch(request_queue_t *q, int force) +{ + struct noop_data *nd = q->elevator->elevator_data; + + if (!list_empty(&nd->queue)) { + struct request *rq; + rq = list_entry(nd->queue.next, struct request, queuelist); + list_del_init(&rq->queuelist); + elv_dispatch_sort(q, rq); + return 1; + } + return 0; +} + +static void noop_add_request(request_queue_t *q, struct request *rq) +{ + struct noop_data *nd = q->elevator->elevator_data; + + list_add_tail(&rq->queuelist, &nd->queue); +} + +static int noop_queue_empty(request_queue_t *q) +{ + struct noop_data *nd = q->elevator->elevator_data; + + return list_empty(&nd->queue); +} + +static struct request * +noop_former_request(request_queue_t *q, struct request *rq) +{ + struct noop_data *nd = q->elevator->elevator_data; + + if (rq->queuelist.prev == &nd->queue) + return NULL; + return list_entry(rq->queuelist.prev, struct request, queuelist); +} + +static struct request * +noop_latter_request(request_queue_t *q, struct request *rq) +{ + struct noop_data *nd = q->elevator->elevator_data; + + if (rq->queuelist.next == &nd->queue) + return NULL; + return list_entry(rq->queuelist.next, struct request, queuelist); +} + +static int noop_init_queue(request_queue_t *q, elevator_t *e) +{ + struct noop_data *nd; + + nd = kmalloc(sizeof(*nd), GFP_KERNEL); + if (!nd) + return -ENOMEM; + INIT_LIST_HEAD(&nd->queue); + e->elevator_data = nd; + return 0; +} + +static void noop_exit_queue(elevator_t *e) +{ + struct noop_data *nd = e->elevator_data; + + BUG_ON(!list_empty(&nd->queue)); + kfree(nd); +} + +static struct elevator_type elevator_noop = { + .ops = { + .elevator_merge_req_fn = noop_merged_requests, + .elevator_dispatch_fn = noop_dispatch, + .elevator_add_req_fn = noop_add_request, + .elevator_queue_empty_fn = noop_queue_empty, + .elevator_former_req_fn = noop_former_request, + .elevator_latter_req_fn = noop_latter_request, + .elevator_init_fn = noop_init_queue, + .elevator_exit_fn = noop_exit_queue, + }, + .elevator_name = "noop", + .elevator_owner = THIS_MODULE, +}; + +static int __init noop_init(void) +{ + return elv_register(&elevator_noop); +} + +static void __exit noop_exit(void) +{ + elv_unregister(&elevator_noop); +} + +module_init(noop_init); +module_exit(noop_exit); + + +MODULE_AUTHOR("Jens Axboe"); +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("No-op IO scheduler"); |