block, cfq: restructure io_cq creation path for io_context interface cleanup

Add elevator_ops->elevator_init_icq_fn() and restructure
cfq_create_cic() and rename it to ioc_create_icq().

The new function expects its caller to pass in io_context, uses
elevator_type->icq_cache, handles generic init, calls the new elevator
operation for elevator specific initialization, and returns pointer to
created or looked up icq.  This leaves cfq_icq_pool variable without
any user.  Removed.

This prepares for io_context interface cleanup and doesn't introduce
any functional difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index 06e4dd568717..c8f1e67a8ebe 100644
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -26,6 +26,7 @@ typedef struct request *(elevator_request_list_fn) (struct request_queue *, stru
 typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
 typedef int (elevator_may_queue_fn) (struct request_queue *, 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 *, gfp_t);
 typedef void (elevator_put_req_fn) (struct request *);
@@ -59,6 +60,7 @@ struct elevator_ops
         elevator_request_list_fn *elevator_former_req_fn;
         elevator_request_list_fn *elevator_latter_req_fn;
 
+        elevator_init_icq_fn *elevator_init_icq_fn;
         elevator_exit_icq_fn *elevator_exit_icq_fn;
 
         elevator_set_req_fn *elevator_set_req_fn;