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, 1 insertions, 89 deletions

diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index 015bb59c0331..158004f1754d 100644
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -23,74 +23,6 @@ enum elv_merge {
 	ELEVATOR_DISCARD_MERGE	= 3,
 };
 
-typedef enum elv_merge (elevator_merge_fn) (struct request_queue *, struct request **,
-				 struct bio *);
-
-typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
-
-typedef void (elevator_merged_fn) (struct request_queue *, struct request *, enum elv_merge);
-
-typedef int (elevator_allow_bio_merge_fn) (struct request_queue *,
-					   struct request *, struct bio *);
-
-typedef int (elevator_allow_rq_merge_fn) (struct request_queue *,
-					  struct request *, struct request *);
-
-typedef void (elevator_bio_merged_fn) (struct request_queue *,
-						struct request *, struct bio *);
-
-typedef int (elevator_dispatch_fn) (struct request_queue *, int);
-
-typedef void (elevator_add_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 *, unsigned int);
-
-typedef void (elevator_init_icq_fn) (struct io_cq *);
-typedef void (elevator_exit_icq_fn) (struct io_cq *);
-typedef int (elevator_set_req_fn) (struct request_queue *, struct request *,
-				   struct bio *, gfp_t);
-typedef void (elevator_put_req_fn) (struct request *);
-typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
-typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
-
-typedef int (elevator_init_fn) (struct request_queue *,
-				struct elevator_type *e);
-typedef void (elevator_exit_fn) (struct elevator_queue *);
-typedef void (elevator_registered_fn) (struct request_queue *);
-
-struct elevator_ops
-{
-	elevator_merge_fn *elevator_merge_fn;
-	elevator_merged_fn *elevator_merged_fn;
-	elevator_merge_req_fn *elevator_merge_req_fn;
-	elevator_allow_bio_merge_fn *elevator_allow_bio_merge_fn;
-	elevator_allow_rq_merge_fn *elevator_allow_rq_merge_fn;
-	elevator_bio_merged_fn *elevator_bio_merged_fn;
-
-	elevator_dispatch_fn *elevator_dispatch_fn;
-	elevator_add_req_fn *elevator_add_req_fn;
-	elevator_activate_req_fn *elevator_activate_req_fn;
-	elevator_deactivate_req_fn *elevator_deactivate_req_fn;
-
-	elevator_completed_req_fn *elevator_completed_req_fn;
-
-	elevator_request_list_fn *elevator_former_req_fn;
-	elevator_request_list_fn *elevator_latter_req_fn;
-
-	elevator_init_icq_fn *elevator_init_icq_fn;	/* see iocontext.h */
-	elevator_exit_icq_fn *elevator_exit_icq_fn;	/* ditto */
-
-	elevator_set_req_fn *elevator_set_req_fn;
-	elevator_put_req_fn *elevator_put_req_fn;
-
-	elevator_may_queue_fn *elevator_may_queue_fn;
-
-	elevator_init_fn *elevator_init_fn;
-	elevator_exit_fn *elevator_exit_fn;
-	elevator_registered_fn *elevator_registered_fn;
-};
-
 struct blk_mq_alloc_data;
 struct blk_mq_hw_ctx;
 
@@ -138,16 +70,15 @@ struct elevator_type
 
 	/* fields provided by elevator implementation */
 	union {
-		struct elevator_ops sq;
 		struct elevator_mq_ops mq;
 	} ops;
+
 	size_t icq_size;	/* see iocontext.h */
 	size_t icq_align;	/* ditto */
 	struct elv_fs_entry *elevator_attrs;
 	char elevator_name[ELV_NAME_MAX];
 	const char *elevator_alias;
 	struct module *elevator_owner;
-	bool uses_mq;
 #ifdef CONFIG_BLK_DEBUG_FS
 	const struct blk_mq_debugfs_attr *queue_debugfs_attrs;
 	const struct blk_mq_debugfs_attr *hctx_debugfs_attrs;
@@ -175,40 +106,25 @@ struct elevator_queue
 	struct kobject kobj;
 	struct mutex sysfs_lock;
 	unsigned int registered:1;
-	unsigned int uses_mq:1;
 	DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
 };
 
 /*
  * block elevator interface
  */
-extern void elv_dispatch_sort(struct request_queue *, struct request *);
-extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
-extern void elv_add_request(struct request_queue *, struct request *, int);
-extern void __elv_add_request(struct request_queue *, struct request *, int);
 extern enum elv_merge elv_merge(struct request_queue *, struct request **,
 		struct bio *);
 extern void elv_merge_requests(struct request_queue *, struct request *,
 			       struct request *);
 extern void elv_merged_request(struct request_queue *, struct request *,
 		enum elv_merge);
-extern void elv_bio_merged(struct request_queue *q, struct request *,
-				struct bio *);
 extern bool elv_attempt_insert_merge(struct request_queue *, struct request *);
-extern void elv_requeue_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_may_queue(struct request_queue *, unsigned int);
-extern void elv_completed_request(struct request_queue *, struct request *);
-extern int elv_set_request(struct request_queue *q, struct request *rq,
-			   struct bio *bio, gfp_t gfp_mask);
-extern void elv_put_request(struct request_queue *, struct request *);
-extern void elv_drain_elevator(struct request_queue *);
 
 /*
  * io scheduler registration
  */
-extern void __init load_default_elevator_module(void);
 extern int elv_register(struct elevator_type *);
 extern void elv_unregister(struct elevator_type *);
 
@@ -260,9 +176,5 @@ enum {
 #define rq_entry_fifo(ptr)	list_entry((ptr), struct request, queuelist)
 #define rq_fifo_clear(rq)	list_del_init(&(rq)->queuelist)
 
-#else /* CONFIG_BLOCK */
-
-static inline void load_default_elevator_module(void) { }
-
 #endif /* CONFIG_BLOCK */
 #endif