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, 2 insertions, 91 deletions

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 8afe3331777e..a9f6db8abcda 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -58,9 +58,6 @@ struct blk_stat_callback;
 
 typedef void (rq_end_io_fn)(struct request *, blk_status_t);
 
-#define BLK_RL_SYNCFULL         (1U << 0)
-#define BLK_RL_ASYNCFULL        (1U << 1)
-
 struct request_list {
         struct request_queue    *q;     /* the queue this rl belongs to */
 #ifdef CONFIG_BLK_CGROUP
@@ -309,11 +306,8 @@ static inline unsigned short req_get_ioprio(struct request *req)
 
 struct blk_queue_ctx;
 
-typedef void (request_fn_proc) (struct request_queue *q);
 typedef blk_qc_t (make_request_fn) (struct request_queue *q, struct bio *bio);
 typedef bool (poll_q_fn) (struct request_queue *q, blk_qc_t);
-typedef int (prep_rq_fn) (struct request_queue *, struct request *);
-typedef void (unprep_rq_fn) (struct request_queue *, struct request *);
 
 struct bio_vec;
 typedef void (softirq_done_fn)(struct request *);
@@ -432,8 +426,6 @@ struct request_queue {
         struct list_head        queue_head;
         struct request          *last_merge;
         struct elevator_queue   *elevator;
-        int                     nr_rqs[2];      /* # allocated [a]sync rqs */
-        int                     nr_rqs_elvpriv; /* # allocated rqs w/ elvpriv */
 
         struct blk_queue_stats  *stats;
         struct rq_qos           *rq_qos;
@@ -446,11 +438,8 @@ struct request_queue {
          */
         struct request_list     root_rl;
 
-        request_fn_proc         *request_fn;
         make_request_fn         *make_request_fn;
         poll_q_fn               *poll_fn;
-        prep_rq_fn              *prep_rq_fn;
-        unprep_rq_fn            *unprep_rq_fn;
         softirq_done_fn         *softirq_done_fn;
         rq_timed_out_fn         *rq_timed_out_fn;
         dma_drain_needed_fn     *dma_drain_needed;
@@ -458,8 +447,6 @@ struct request_queue {
         init_rq_fn              *init_rq_fn;
         /* Called just before a request is freed */
         exit_rq_fn              *exit_rq_fn;
-        /* Called from inside blk_get_request() */
-        void (*initialize_rq_fn)(struct request *rq);
 
         const struct blk_mq_ops *mq_ops;
 
@@ -475,17 +462,6 @@ struct request_queue {
         struct blk_mq_hw_ctx    **queue_hw_ctx;
         unsigned int            nr_hw_queues;
 
-        /*
-         * Dispatch queue sorting
-         */
-        sector_t                end_sector;
-        struct request          *boundary_rq;
-
-        /*
-         * Delayed queue handling
-         */
-        struct delayed_work     delay_work;
-
         struct backing_dev_info *backing_dev_info;
 
         /*
@@ -548,9 +524,6 @@ struct request_queue {
          * queue settings
          */
         unsigned long           nr_requests;    /* Max # of requests */
-        unsigned int            nr_congestion_on;
-        unsigned int            nr_congestion_off;
-        unsigned int            nr_batching;
 
         unsigned int            dma_drain_size;
         void                    *dma_drain_buffer;
@@ -560,13 +533,6 @@ struct request_queue {
         unsigned int            nr_sorted;
         unsigned int            in_flight[2];
 
-        /*
-         * Number of active block driver functions for which blk_drain_queue()
-         * must wait. Must be incremented around functions that unlock the
-         * queue_lock internally, e.g. scsi_request_fn().
-         */
-        unsigned int            request_fn_active;
-
         unsigned int            rq_timeout;
         int                     poll_nsec;
 
@@ -740,11 +706,6 @@ bool blk_queue_flag_test_and_clear(unsigned int flag, struct request_queue *q);
 extern void blk_set_pm_only(struct request_queue *q);
 extern void blk_clear_pm_only(struct request_queue *q);
 
-static inline int queue_in_flight(struct request_queue *q)
-{
-        return q->in_flight[0] + q->in_flight[1];
-}
-
 static inline bool blk_account_rq(struct request *rq)
 {
         return (rq->rq_flags & RQF_STARTED) && !blk_rq_is_passthrough(rq);
@@ -765,7 +726,7 @@ static inline bool blk_account_rq(struct request *rq)
  */
 static inline bool queue_is_rq_based(struct request_queue *q)
 {
-        return q->request_fn || q->mq_ops;
+        return q->mq_ops;
 }
 
 static inline unsigned int blk_queue_cluster(struct request_queue *q)
@@ -828,27 +789,6 @@ static inline bool rq_is_sync(struct request *rq)
         return op_is_sync(rq->cmd_flags);
 }
 
-static inline bool blk_rl_full(struct request_list *rl, bool sync)
-{
-        unsigned int flag = sync ? BLK_RL_SYNCFULL : BLK_RL_ASYNCFULL;
-
-        return rl->flags & flag;
-}
-
-static inline void blk_set_rl_full(struct request_list *rl, bool sync)
-{
-        unsigned int flag = sync ? BLK_RL_SYNCFULL : BLK_RL_ASYNCFULL;
-
-        rl->flags |= flag;
-}
-
-static inline void blk_clear_rl_full(struct request_list *rl, bool sync)
-{
-        unsigned int flag = sync ? BLK_RL_SYNCFULL : BLK_RL_ASYNCFULL;
-
-        rl->flags &= ~flag;
-}
-
 static inline bool rq_mergeable(struct request *rq)
 {
         if (blk_rq_is_passthrough(rq))
@@ -969,7 +909,6 @@ extern void blk_put_request(struct request *);
 extern void __blk_put_request(struct request_queue *, struct request *);
 extern struct request *blk_get_request(struct request_queue *, unsigned int op,
                                        blk_mq_req_flags_t flags);
-extern void blk_requeue_request(struct request_queue *, struct request *);
 extern int blk_lld_busy(struct request_queue *q);
 extern int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
                              struct bio_set *bs, gfp_t gfp_mask,
@@ -979,7 +918,6 @@ extern void blk_rq_unprep_clone(struct request *rq);
 extern blk_status_t blk_insert_cloned_request(struct request_queue *q,
                                      struct request *rq);
 extern int blk_rq_append_bio(struct request *rq, struct bio **bio);
-extern void blk_delay_queue(struct request_queue *, unsigned long);
 extern void blk_queue_split(struct request_queue *, struct bio **);
 extern void blk_recount_segments(struct request_queue *, struct bio *);
 extern int scsi_verify_blk_ioctl(struct block_device *, unsigned int);
@@ -992,15 +930,7 @@ extern int sg_scsi_ioctl(struct request_queue *, struct gendisk *, fmode_t,
 
 extern int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags);
 extern void blk_queue_exit(struct request_queue *q);
-extern void blk_start_queue(struct request_queue *q);
-extern void blk_start_queue_async(struct request_queue *q);
-extern void blk_stop_queue(struct request_queue *q);
 extern void blk_sync_queue(struct request_queue *q);
-extern void __blk_stop_queue(struct request_queue *q);
-extern void __blk_run_queue(struct request_queue *q);
-extern void __blk_run_queue_uncond(struct request_queue *q);
-extern void blk_run_queue(struct request_queue *);
-extern void blk_run_queue_async(struct request_queue *q);
 extern int blk_rq_map_user(struct request_queue *, struct request *,
                            struct rq_map_data *, void __user *, unsigned long,
                            gfp_t);
@@ -1155,13 +1085,6 @@ static inline unsigned int blk_rq_count_bios(struct request *rq)
         return nr_bios;
 }
 
-/*
- * Request issue related functions.
- */
-extern struct request *blk_peek_request(struct request_queue *q);
-extern void blk_start_request(struct request *rq);
-extern struct request *blk_fetch_request(struct request_queue *q);
-
 void blk_steal_bios(struct bio_list *list, struct request *rq);
 
 /*
@@ -1179,9 +1102,6 @@ void blk_steal_bios(struct bio_list *list, struct request *rq);
  */
 extern bool blk_update_request(struct request *rq, blk_status_t error,
                                unsigned int nr_bytes);
-extern void blk_finish_request(struct request *rq, blk_status_t error);
-extern bool blk_end_request(struct request *rq, blk_status_t error,
-                            unsigned int nr_bytes);
 extern void blk_end_request_all(struct request *rq, blk_status_t error);
 extern bool __blk_end_request(struct request *rq, blk_status_t error,
                               unsigned int nr_bytes);
@@ -1190,15 +1110,10 @@ extern bool __blk_end_request_cur(struct request *rq, blk_status_t error);
 
 extern void __blk_complete_request(struct request *);
 extern void blk_abort_request(struct request *);
-extern void blk_unprep_request(struct request *);
 
 /*
  * Access functions for manipulating queue properties
  */
-extern struct request_queue *blk_init_queue_node(request_fn_proc *rfn,
-                                        spinlock_t *lock, int node_id);
-extern struct request_queue *blk_init_queue(request_fn_proc *, spinlock_t *);
-extern int blk_init_allocated_queue(struct request_queue *);
 extern void blk_cleanup_queue(struct request_queue *);
 extern void blk_queue_make_request(struct request_queue *, make_request_fn *);
 extern void blk_queue_bounce_limit(struct request_queue *, u64);
@@ -1239,8 +1154,6 @@ extern int blk_queue_dma_drain(struct request_queue *q,
                                void *buf, unsigned int size);
 extern void blk_queue_segment_boundary(struct request_queue *, unsigned long);
 extern void blk_queue_virt_boundary(struct request_queue *, unsigned long);
-extern void blk_queue_prep_rq(struct request_queue *, prep_rq_fn *pfn);
-extern void blk_queue_unprep_rq(struct request_queue *, unprep_rq_fn *ufn);
 extern void blk_queue_dma_alignment(struct request_queue *, int);
 extern void blk_queue_update_dma_alignment(struct request_queue *, int);
 extern void blk_queue_softirq_done(struct request_queue *, softirq_done_fn *);
@@ -1298,7 +1211,6 @@ extern void blk_set_queue_dying(struct request_queue *);
  * schedule() where blk_schedule_flush_plug() is called.
  */
 struct blk_plug {
-        struct list_head list; /* requests */
         struct list_head mq_list; /* blk-mq requests */
         struct list_head cb_list; /* md requires an unplug callback */
 };
@@ -1339,8 +1251,7 @@ static inline bool blk_needs_flush_plug(struct task_struct *tsk)
         struct blk_plug *plug = tsk->plug;
 
         return plug &&
-                (!list_empty(&plug->list) ||
-                 !list_empty(&plug->mq_list) ||
+                 (!list_empty(&plug->mq_list) ||
                  !list_empty(&plug->cb_list));
 }