block/laptop_mode: Convert timers to use timer_setup()

In preparation for unconditionally passing the struct timer_list pointer to
all timer callbacks, switch to using the new timer_setup() and from_timer()
to pass the timer pointer explicitly.

Cc: Jens Axboe <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: Andrew Morton <[e-mail]>
Cc: Jan Kara <[e-mail]>
Cc: Johannes Weiner <[e-mail]>
Cc: Nicholas Piggin <[e-mail]>
Cc: Vladimir Davydov <[e-mail]>
Cc: Matthew Wilcox <[e-mail]>
Cc: Jeff Layton <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Signed-off-by: Kees Cook <[e-mail]>

block/blk-core.c

···
 	wake_up_all(&q->mq_freeze_wq);
 }
 
-static void blk_rq_timed_out_timer(unsigned long data)
+static void blk_rq_timed_out_timer(struct timer_list *t)
 {
-	struct request_queue *q = (struct request_queue *)data;
+	struct request_queue *q = from_timer(q, t, timeout);
 
 	kblockd_schedule_work(&q->timeout_work);
 }
···
 	q->backing_dev_info->name = "block";
 	q->node = node_id;
 
-	setup_timer(&q->backing_dev_info->laptop_mode_wb_timer,
-		    laptop_mode_timer_fn, (unsigned long) q);
-	setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
+	timer_setup(&q->backing_dev_info->laptop_mode_wb_timer,
+		    laptop_mode_timer_fn, 0);
+	timer_setup(&q->timeout, blk_rq_timed_out_timer, 0);
 	INIT_WORK(&q->timeout_work, NULL);
 	INIT_LIST_HEAD(&q->queue_head);
 	INIT_LIST_HEAD(&q->timeout_list);

include/linux/writeback.h

···
 void laptop_io_completion(struct backing_dev_info *info);
 void laptop_sync_completion(void);
 void laptop_mode_sync(struct work_struct *work);
-void laptop_mode_timer_fn(unsigned long data);
+void laptop_mode_timer_fn(struct timer_list *t);
 #else
 static inline void laptop_sync_completion(void) { }
 #endif

mm/page-writeback.c

···
 }
 
 #ifdef CONFIG_BLOCK
-void laptop_mode_timer_fn(unsigned long data)
+void laptop_mode_timer_fn(struct timer_list *t)
 {
-	struct request_queue *q = (struct request_queue *)data;
+	struct backing_dev_info *backing_dev_info =
+		from_timer(backing_dev_info, t, laptop_mode_wb_timer);
 
-	wakeup_flusher_threads_bdi(q->backing_dev_info, WB_REASON_LAPTOP_TIMER);
+	wakeup_flusher_threads_bdi(backing_dev_info, WB_REASON_LAPTOP_TIMER);
 }
 
 /*