block: remove dead elevator code

This removes a bunch of core and elevator related code. On the core
front, we remove anything related to queue running, draining,
initialization, plugging, and congestions. We also kill anything
related to request allocation, merging, retrieval, and completion.

Remove any checking for single queue IO schedulers, as they no
longer exist. This means we can also delete a bunch of code related
to request issue, adding, completion, etc - and all the SQ related
ops and helpers.

Also kill the load_default_modules(), as all that did was provide
for a way to load the default single queue elevator.

Tested-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 0 insertions, 51 deletions

diff --git a/block/blk.h b/block/blk.h
index 57a302bf5a70..e2604ae7ddfa 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -7,12 +7,6 @@
 #include <xen/xen.h>
 #include "blk-mq.h"
 
-/* Amount of time in which a process may batch requests */
-#define BLK_BATCH_TIME	(HZ/50UL)
-
-/* Number of requests a "batching" process may submit */
-#define BLK_BATCH_REQ	32
-
 /* Max future timer expiry for timeouts */
 #define BLK_MAX_TIMEOUT		(5 * HZ)
 
@@ -132,9 +126,6 @@ void blk_exit_rl(struct request_queue *q, struct request_list *rl);
 void blk_exit_queue(struct request_queue *q);
 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
 			struct bio *bio);
-void blk_queue_bypass_start(struct request_queue *q);
-void blk_queue_bypass_end(struct request_queue *q);
-void __blk_queue_free_tags(struct request_queue *q);
 void blk_freeze_queue(struct request_queue *q);
 
 static inline void blk_queue_enter_live(struct request_queue *q)
@@ -281,23 +272,6 @@ static inline bool blk_rq_is_complete(struct request *rq)
 
 void blk_insert_flush(struct request *rq);
 
-static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
-{
-	struct elevator_queue *e = q->elevator;
-
-	if (e->type->ops.sq.elevator_activate_req_fn)
-		e->type->ops.sq.elevator_activate_req_fn(q, rq);
-}
-
-static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
-{
-	struct elevator_queue *e = q->elevator;
-
-	if (e->type->ops.sq.elevator_deactivate_req_fn)
-		e->type->ops.sq.elevator_deactivate_req_fn(q, rq);
-}
-
-int elevator_init(struct request_queue *);
 int elevator_init_mq(struct request_queue *q);
 int elevator_switch_mq(struct request_queue *q,
 			      struct elevator_type *new_e);
@@ -332,31 +306,8 @@ void blk_rq_set_mixed_merge(struct request *rq);
 bool blk_rq_merge_ok(struct request *rq, struct bio *bio);
 enum elv_merge blk_try_merge(struct request *rq, struct bio *bio);
 
-void blk_queue_congestion_threshold(struct request_queue *q);
-
 int blk_dev_init(void);
 
-
-/*
- * Return the threshold (number of used requests) at which the queue is
- * considered to be congested.  It include a little hysteresis to keep the
- * context switch rate down.
- */
-static inline int queue_congestion_on_threshold(struct request_queue *q)
-{
-	return q->nr_congestion_on;
-}
-
-/*
- * The threshold at which a queue is considered to be uncongested
- */
-static inline int queue_congestion_off_threshold(struct request_queue *q)
-{
-	return q->nr_congestion_off;
-}
-
-extern int blk_update_nr_requests(struct request_queue *, unsigned int);
-
 /*
  * Contribute to IO statistics IFF:
  *
@@ -478,8 +429,6 @@ static inline void blk_queue_bounce(struct request_queue *q, struct bio **bio)
 }
 #endif /* CONFIG_BOUNCE */
 
-extern void blk_drain_queue(struct request_queue *q);
-
 #ifdef CONFIG_BLK_CGROUP_IOLATENCY
 extern int blk_iolatency_init(struct request_queue *q);
 #else