writeback: move wb_wakeup_delayed defination to fs-writeback.c

The wb_wakeup_delayed is only used in fs-writeback.c. Move it to
fs-writeback.c after defination of wb_wakeup and make it static.

Signed-off-by: Kemeng Shi <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Reviewed-by: Jan Kara <[e-mail]>
Signed-off-by: Christian Brauner <[e-mail]>

fs/fs-writeback.c

···
 	spin_unlock_irq(&wb->work_lock);
 }
 
+/*
+ * This function is used when the first inode for this wb is marked dirty. It
+ * wakes-up the corresponding bdi thread which should then take care of the
+ * periodic background write-out of dirty inodes. Since the write-out would
+ * starts only 'dirty_writeback_interval' centisecs from now anyway, we just
+ * set up a timer which wakes the bdi thread up later.
+ *
+ * Note, we wouldn't bother setting up the timer, but this function is on the
+ * fast-path (used by '__mark_inode_dirty()'), so we save few context switches
+ * by delaying the wake-up.
+ *
+ * We have to be careful not to postpone flush work if it is scheduled for
+ * earlier. Thus we use queue_delayed_work().
+ */
+static void wb_wakeup_delayed(struct bdi_writeback *wb)
+{
+	unsigned long timeout;
+
+	timeout = msecs_to_jiffies(dirty_writeback_interval * 10);
+	spin_lock_irq(&wb->work_lock);
+	if (test_bit(WB_registered, &wb->state))
+		queue_delayed_work(bdi_wq, &wb->dwork, timeout);
+	spin_unlock_irq(&wb->work_lock);
+}
+
 static void finish_writeback_work(struct bdi_writeback *wb,
 				  struct wb_writeback_work *work)
 {

include/linux/backing-dev.h

···
 
 void wb_start_background_writeback(struct bdi_writeback *wb);
 void wb_workfn(struct work_struct *work);
-void wb_wakeup_delayed(struct bdi_writeback *wb);
 
 void wb_wait_for_completion(struct wb_completion *done);
 

mm/backing-dev.c

···
 }
 subsys_initcall(default_bdi_init);
 
-/*
- * This function is used when the first inode for this wb is marked dirty. It
- * wakes-up the corresponding bdi thread which should then take care of the
- * periodic background write-out of dirty inodes. Since the write-out would
- * starts only 'dirty_writeback_interval' centisecs from now anyway, we just
- * set up a timer which wakes the bdi thread up later.
- *
- * Note, we wouldn't bother setting up the timer, but this function is on the
- * fast-path (used by '__mark_inode_dirty()'), so we save few context switches
- * by delaying the wake-up.
- *
- * We have to be careful not to postpone flush work if it is scheduled for
- * earlier. Thus we use queue_delayed_work().
- */
-void wb_wakeup_delayed(struct bdi_writeback *wb)
-{
-	unsigned long timeout;
-
-	timeout = msecs_to_jiffies(dirty_writeback_interval * 10);
-	spin_lock_irq(&wb->work_lock);
-	if (test_bit(WB_registered, &wb->state))
-		queue_delayed_work(bdi_wq, &wb->dwork, timeout);
-	spin_unlock_irq(&wb->work_lock);
-}
-
 static void wb_update_bandwidth_workfn(struct work_struct *work)
 {
 	struct bdi_writeback *wb = container_of(to_delayed_work(work),