mm: page-writeback: inline account_page_dirtied() into single caller

A follow-up patch would have changed the call signature.  To save the
trouble, just fold it instead.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: <stable@vger.kernel.org>	[3.17.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index ff24c9d..ff6a5b0 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2116,23 +2116,6 @@
 EXPORT_SYMBOL(account_page_dirtied);
 
 /*
- * Helper function for set_page_writeback family.
- *
- * The caller must hold mem_cgroup_begin/end_update_page_stat() lock
- * while calling this function.
- * See test_set_page_writeback for example.
- *
- * NOTE: Unlike account_page_dirtied this does not rely on being atomic
- * wrt interrupts.
- */
-void account_page_writeback(struct page *page)
-{
-	mem_cgroup_inc_page_stat(page, MEM_CGROUP_STAT_WRITEBACK);
-	inc_zone_page_state(page, NR_WRITEBACK);
-}
-EXPORT_SYMBOL(account_page_writeback);
-
-/*
  * For address_spaces which do not use buffers.  Just tag the page as dirty in
  * its radix tree.
  *
@@ -2410,8 +2393,10 @@
 	} else {
 		ret = TestSetPageWriteback(page);
 	}
-	if (!ret)
-		account_page_writeback(page);
+	if (!ret) {
+		mem_cgroup_inc_page_stat(page, MEM_CGROUP_STAT_WRITEBACK);
+		inc_zone_page_state(page, NR_WRITEBACK);
+	}
 	mem_cgroup_end_update_page_stat(page, &locked, &memcg_flags);
 	return ret;