1 files changed, 11 insertions, 4 deletions

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 214e90b94946..bfd4ee59cb88 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -326,17 +326,24 @@ static inline int page_swapcount(struct page *page)
 }
 
 /*
- * We can use this swap cache entry directly
- * if there are no other references to it.
+ * We can write to an anon page without COW if there are no other references
+ * to it.  And as a side-effect, free up its swap: because the old content
+ * on disk will never be read, and seeking back there to write new content
+ * later would only waste time away from clustering.
  */
-int can_share_swap_page(struct page *page)
+int reuse_swap_page(struct page *page)
 {
         int count;
 
         VM_BUG_ON(!PageLocked(page));
         count = page_mapcount(page);
-        if (count <= 1 && PageSwapCache(page))
+        if (count <= 1 && PageSwapCache(page)) {
                 count += page_swapcount(page);
+                if (count == 1 && !PageWriteback(page)) {
+                        delete_from_swap_cache(page);
+                        SetPageDirty(page);
+                }
+        }
         return count == 1;
 }