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, 36 deletions

diff --git a/block/blk-settings.c b/block/blk-settings.c
index ac8b8ba4b126..39c3c301a687 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -20,40 +20,6 @@ EXPORT_SYMBOL(blk_max_low_pfn);
 
 unsigned long blk_max_pfn;
 
-/**
- * blk_queue_prep_rq - set a prepare_request function for queue
- * @q:		queue
- * @pfn:	prepare_request function
- *
- * It's possible for a queue to register a prepare_request callback which
- * is invoked before the request is handed to the request_fn. The goal of
- * the function is to prepare a request for I/O, it can be used to build a
- * cdb from the request data for instance.
- *
- */
-void blk_queue_prep_rq(struct request_queue *q, prep_rq_fn *pfn)
-{
-	q->prep_rq_fn = pfn;
-}
-EXPORT_SYMBOL(blk_queue_prep_rq);
-
-/**
- * blk_queue_unprep_rq - set an unprepare_request function for queue
- * @q:		queue
- * @ufn:	unprepare_request function
- *
- * It's possible for a queue to register an unprepare_request callback
- * which is invoked before the request is finally completed. The goal
- * of the function is to deallocate any data that was allocated in the
- * prepare_request callback.
- *
- */
-void blk_queue_unprep_rq(struct request_queue *q, unprep_rq_fn *ufn)
-{
-	q->unprep_rq_fn = ufn;
-}
-EXPORT_SYMBOL(blk_queue_unprep_rq);
-
 void blk_queue_softirq_done(struct request_queue *q, softirq_done_fn *fn)
 {
 	q->softirq_done_fn = fn;
@@ -163,8 +129,6 @@ void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn)
 
 	q->make_request_fn = mfn;
 	blk_queue_dma_alignment(q, 511);
-	blk_queue_congestion_threshold(q);
-	q->nr_batching = BLK_BATCH_REQ;
 
 	blk_set_default_limits(&q->limits);
 }