/*
* can we safely merge with this request?
*/
-int elv_rq_merge_ok(struct request *rq, struct bio *bio)
+bool elv_rq_merge_ok(struct request *rq, struct bio *bio)
{
- if (!rq_mergeable(rq))
- return 0;
-
- /*
- * Don't merge file system requests and discard requests
- */
- if ((bio->bi_rw & REQ_DISCARD) != (rq->bio->bi_rw & REQ_DISCARD))
- return 0;
-
- /*
- * Don't merge discard requests and secure discard requests
- */
- if ((bio->bi_rw & REQ_SECURE) != (rq->bio->bi_rw & REQ_SECURE))
- return 0;
-
- /*
- * different data direction or already started, don't merge
- */
- if (bio_data_dir(bio) != rq_data_dir(rq))
- return 0;
-
- /*
- * must be same device and not a special request
- */
- if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special)
- return 0;
-
- /*
- * only merge integrity protected bio into ditto rq
- */
- if (bio_integrity(bio) != blk_integrity_rq(rq))
+ if (!blk_rq_merge_ok(rq, bio))
return 0;
if (!elv_iosched_allow_merge(rq, bio))
}
EXPORT_SYMBOL(elv_rq_merge_ok);
-int elv_try_merge(struct request *__rq, struct bio *bio)
-{
- int ret = ELEVATOR_NO_MERGE;
-
- /*
- * we can merge and sequence is ok, check if it's possible
- */
- if (elv_rq_merge_ok(__rq, bio)) {
- if (blk_rq_pos(__rq) + blk_rq_sectors(__rq) == bio->bi_sector)
- ret = ELEVATOR_BACK_MERGE;
- else if (blk_rq_pos(__rq) - bio_sectors(bio) == bio->bi_sector)
- ret = ELEVATOR_FRONT_MERGE;
- }
-
- return ret;
-}
-
static struct elevator_type *elevator_find(const char *name)
{
struct elevator_type *e;
return e;
}
-static int elevator_init_queue(struct request_queue *q,
- struct elevator_queue *eq)
-{
- eq->elevator_data = eq->type->ops.elevator_init_fn(q);
- if (eq->elevator_data)
- return 0;
- return -ENOMEM;
-}
-
static char chosen_elevator[ELV_NAME_MAX];
static int __init elevator_setup(char *str)
int elevator_init(struct request_queue *q, char *name)
{
struct elevator_type *e = NULL;
- struct elevator_queue *eq;
int err;
if (unlikely(q->elevator))
}
}
- eq = elevator_alloc(q, e);
- if (!eq)
+ q->elevator = elevator_alloc(q, e);
+ if (!q->elevator)
return -ENOMEM;
- err = elevator_init_queue(q, eq);
+ err = e->ops.elevator_init_fn(q);
if (err) {
- kobject_put(&eq->kobj);
+ kobject_put(&q->elevator->kobj);
return err;
}
- q->elevator = eq;
return 0;
}
EXPORT_SYMBOL(elevator_init);
/*
* First try one-hit cache.
*/
- if (q->last_merge) {
- ret = elv_try_merge(q->last_merge, bio);
+ if (q->last_merge && elv_rq_merge_ok(q->last_merge, bio)) {
+ ret = blk_try_merge(q->last_merge, bio);
if (ret != ELEVATOR_NO_MERGE) {
*req = q->last_merge;
return ret;
.release = elevator_release,
};
-int __elv_register_queue(struct request_queue *q, struct elevator_queue *e)
+int elv_register_queue(struct request_queue *q)
{
+ struct elevator_queue *e = q->elevator;
int error;
error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched");
}
return error;
}
-
-int elv_register_queue(struct request_queue *q)
-{
- return __elv_register_queue(q, q->elevator);
-}
EXPORT_SYMBOL(elv_register_queue);
void elv_unregister_queue(struct request_queue *q)
*/
static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
{
- struct elevator_queue *old_elevator, *e;
+ struct elevator_queue *old = q->elevator;
+ bool registered = old->registered;
int err;
- /* allocate new elevator */
- e = elevator_alloc(q, new_e);
- if (!e)
- return -ENOMEM;
-
- err = elevator_init_queue(q, e);
- if (err) {
- kobject_put(&e->kobj);
- return err;
- }
-
- /* turn on BYPASS and drain all requests w/ elevator private data */
+ /*
+ * Turn on BYPASS and drain all requests w/ elevator private data.
+ * Block layer doesn't call into a quiesced elevator - all requests
+ * are directly put on the dispatch list without elevator data
+ * using INSERT_BACK. All requests have SOFTBARRIER set and no
+ * merge happens either.
+ */
elv_quiesce_start(q);
- /* unregister old queue, register new one and kill old elevator */
- if (q->elevator->registered) {
+ /* unregister and clear all auxiliary data of the old elevator */
+ if (registered)
elv_unregister_queue(q);
- err = __elv_register_queue(q, e);
- if (err)
- goto fail_register;
- }
- /* done, clear io_cq's, switch elevators and turn off BYPASS */
spin_lock_irq(q->queue_lock);
ioc_clear_queue(q);
- old_elevator = q->elevator;
- q->elevator = e;
spin_unlock_irq(q->queue_lock);
- elevator_exit(old_elevator);
+ /* allocate, init and register new elevator */
+ err = -ENOMEM;
+ q->elevator = elevator_alloc(q, new_e);
+ if (!q->elevator)
+ goto fail_init;
+
+ err = new_e->ops.elevator_init_fn(q);
+ if (err) {
+ kobject_put(&q->elevator->kobj);
+ goto fail_init;
+ }
+
+ if (registered) {
+ err = elv_register_queue(q);
+ if (err)
+ goto fail_register;
+ }
+
+ /* done, kill the old one and finish */
+ elevator_exit(old);
elv_quiesce_end(q);
- blk_add_trace_msg(q, "elv switch: %s", e->type->elevator_name);
+ blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name);
return 0;
fail_register:
- /*
- * switch failed, exit the new io scheduler and reattach the old
- * one again (along with re-adding the sysfs dir)
- */
- elevator_exit(e);
+ elevator_exit(q->elevator);
+fail_init:
+ /* switch failed, restore and re-register old elevator */
+ q->elevator = old;
elv_register_queue(q);
elv_quiesce_end(q);
git.samba.org / sfrench / cifs-2.6.git / blobdiff