fs: kill 'nr_pages' argument from wakeup_flusher_threads()

Everybody is passing in 0 now, let's get rid of the argument.
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/fs-writeback.c

@@ -1947,12 +1947,12 @@ void wb_workfn(struct work_struct *work)
 }
 
 /*
- * Start writeback of `nr_pages' pages.  If `nr_pages' is zero, write back
- * the whole world.
+ * Wakeup the flusher threads to start writeback of all currently dirty pages
  */
-void wakeup_flusher_threads(long nr_pages, enum wb_reason reason)
+void wakeup_flusher_threads(enum wb_reason reason)
 {
 	struct backing_dev_info *bdi;
+	long nr_pages;
 
 	/*
 	 * If we are expecting writeback progress we must submit plugged IO.
@@ -1960,8 +1960,7 @@ void wakeup_flusher_threads(long nr_pages, enum wb_reason reason)
 	if (blk_needs_flush_plug(current))
 		blk_schedule_flush_plug(current);
 
-	if (!nr_pages)
-		nr_pages = get_nr_dirty_pages();
+	nr_pages = get_nr_dirty_pages();
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) {

fs/sync.c

@@ -108,7 +108,7 @@ SYSCALL_DEFINE0(sync)
 {
 	int nowait = 0, wait = 1;
 
-	wakeup_flusher_threads(0, WB_REASON_SYNC);
+	wakeup_flusher_threads(WB_REASON_SYNC);
 	iterate_supers(sync_inodes_one_sb, NULL);
 	iterate_supers(sync_fs_one_sb, &nowait);
 	iterate_supers(sync_fs_one_sb, &wait);

include/linux/writeback.h

@@ -189,7 +189,7 @@ bool try_to_writeback_inodes_sb(struct super_block *, enum wb_reason reason);
 bool try_to_writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
 				   enum wb_reason reason);
 void sync_inodes_sb(struct super_block *);
-void wakeup_flusher_threads(long nr_pages, enum wb_reason reason);
+void wakeup_flusher_threads(enum wb_reason reason);
 void inode_wait_for_writeback(struct inode *inode);
 
 /* writeback.h requires fs.h; it, too, is not included from here. */

mm/vmscan.c

@@ -1867,7 +1867,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
 		 * also allow kswapd to start writing pages during reclaim.
 		 */
 		if (stat.nr_unqueued_dirty == nr_taken) {
-			wakeup_flusher_threads(0, WB_REASON_VMSCAN);
+			wakeup_flusher_threads(WB_REASON_VMSCAN);
 			set_bit(PGDAT_DIRTY, &pgdat->flags);
 		}