[PATCH] call mm/page-writeback.c:set_ratelimit() when new pages are hot-added

ratelimit_pages in page-writeback.c is recalculated (in set_ratelimit())
every time a CPU is hot-added/removed.  But this value is not recalculated
when new pages are hot-added.

This patch fixes that problem by calling set_ratelimit() when new pages
are hot-added.

[[email protected]: cleanups]
Signed-off-by: Chandra Seetharaman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 56a23a0..9d4074e 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -117,6 +117,7 @@
 int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
 			   loff_t pos, loff_t count);
 void set_page_dirty_balance(struct page *page);
+void writeback_set_ratelimit(void);
 
 /* pdflush.c */
 extern int nr_pdflush_threads;	/* Global so it can be exported to sysctl