mm: move all laptop_mode handling to backing-dev.c

[Christoph Hellwig]

It isn't block-device specific and oddly spread over multiple files
at the moment:

TODO: audit that the unregistration changes are fine

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 block/blk-core.c          |  3 ---
 include/linux/writeback.h |  6 ------
 mm/backing-dev.c          | 36 ++++++++++++++++++++++++++++++++++++
 mm/page-writeback.c       | 36 ------------------------------------
 4 files changed, 36 insertions(+), 45 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 14f7674fa0b1..f5f916b28c40 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -662,7 +662,6 @@ void blk_cleanup_queue(struct request_queue *q)
 	blk_flush_integrity();
 
 	/* @q won't process any more request, flush async actions */
-	del_timer_sync(&q->backing_dev_info->laptop_mode_wb_timer);
 	blk_sync_queue(q);
 
 	if (q->mq_ops)
@@ -841,8 +840,6 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
 	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);
 	INIT_LIST_HEAD(&q->queue_head);
 	INIT_LIST_HEAD(&q->timeout_list);
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 9c0091678af4..e6ba35a5e1f7 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -327,14 +327,8 @@ static inline void cgroup_writeback_umount(void)
 /*
  * mm/page-writeback.c
  */
-#ifdef CONFIG_BLOCK
 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);
-#else
-static inline void laptop_sync_completion(void) { }
-#endif
 bool node_dirty_ok(struct pglist_data *pgdat);
 int wb_domain_init(struct wb_domain *dom, gfp_t gfp);
 #ifdef CONFIG_CGROUP_WRITEBACK
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index e19606bb41a0..cb36f07f2af2 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -822,6 +822,38 @@ static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
 
 #endif	/* CONFIG_CGROUP_WRITEBACK */
 
+static void laptop_mode_timer_fn(unsigned long data)
+{
+	struct backing_dev_info *bdi = (struct backing_dev_info *)data;
+
+	wakeup_flusher_threads_bdi(bdi, WB_REASON_LAPTOP_TIMER);
+}
+
+/*
+ * We've spun up the disk and we're in laptop mode: schedule writeback
+ * of all dirty data a few seconds from now.  If the flush is already scheduled
+ * then push it back - the user is still using the disk.
+ */
+void laptop_io_completion(struct backing_dev_info *bdi)
+{
+	mod_timer(&bdi->laptop_mode_wb_timer, jiffies + laptop_mode);
+}
+
+/*
+ * We're in laptop mode and we've just synced. The sync's writes will have
+ * caused another writeback to be scheduled by laptop_io_completion.
+ * Nothing needs to be written back anymore, so we unschedule the writeback.
+ */
+void laptop_sync_completion(void)
+{
+	struct backing_dev_info *bdi;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(bdi, &bdi_list, bdi_list)
+		del_timer(&bdi->laptop_mode_wb_timer);
+	rcu_read_unlock();
+}
+
 static int bdi_init(struct backing_dev_info *bdi)
 {
 	int ret;
@@ -835,6 +867,8 @@ static int bdi_init(struct backing_dev_info *bdi)
 	INIT_LIST_HEAD(&bdi->bdi_list);
 	INIT_LIST_HEAD(&bdi->wb_list);
 	init_waitqueue_head(&bdi->wb_waitq);
+	setup_timer(&bdi->laptop_mode_wb_timer,
+		    laptop_mode_timer_fn, (unsigned long)bdi);
 
 	ret = cgwb_bdi_init(bdi);
 
@@ -916,6 +950,8 @@ EXPORT_SYMBOL(bdi_register_owner);
  */
 static void bdi_remove_from_list(struct backing_dev_info *bdi)
 {
+	del_timer_sync(&bdi->laptop_mode_wb_timer);
+
 	spin_lock_bh(&bdi_lock);
 	list_del_rcu(&bdi->bdi_list);
 	spin_unlock_bh(&bdi_lock);
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 8d1fc593bce8..f8fe90dc529d 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1976,42 +1976,6 @@ int dirty_writeback_centisecs_handler(struct ctl_table *table, int write,
 	return 0;
 }
 
-#ifdef CONFIG_BLOCK
-void laptop_mode_timer_fn(unsigned long data)
-{
-	struct request_queue *q = (struct request_queue *)data;
-
-	wakeup_flusher_threads_bdi(q->backing_dev_info, WB_REASON_LAPTOP_TIMER);
-}
-
-/*
- * We've spun up the disk and we're in laptop mode: schedule writeback
- * of all dirty data a few seconds from now.  If the flush is already scheduled
- * then push it back - the user is still using the disk.
- */
-void laptop_io_completion(struct backing_dev_info *info)
-{
-	mod_timer(&info->laptop_mode_wb_timer, jiffies + laptop_mode);
-}
-
-/*
- * We're in laptop mode and we've just synced. The sync's writes will have
- * caused another writeback to be scheduled by laptop_io_completion.
- * Nothing needs to be written back anymore, so we unschedule the writeback.
- */
-void laptop_sync_completion(void)
-{
-	struct backing_dev_info *bdi;
-
-	rcu_read_lock();
-
-	list_for_each_entry_rcu(bdi, &bdi_list, bdi_list)
-		del_timer(&bdi->laptop_mode_wb_timer);
-
-	rcu_read_unlock();
-}
-#endif
-
 /*
  * If ratelimit_pages is too high then we can get into dirty-data overload
  * if a large number of processes all perform writes at the same time.
-- 
2.14.1