[PATCH] pagemap_lru_lock wrapup

Some fallout from the pagemap_lru_lock changes:

- lru_cache_del() is no longer used.  Kill it.

- page_cache_release() almost never actually frees pages.  So inline
  page_cache_release() and move its rarely-called slow path into (the
  misnamed) mm/swap.c

- update the locking comment in filemap.c.  pagemap_lru_lock used to
  be one of the outermost locks in the VM locking hierarchy.  Now, we
  never take any other locks while holding pagemap_lru_lock.  So it
  doesn't have any relationship with anything.

- put_page() now removes pages from the LRU on the final put.  The
  lock is interrupt safe.

3 files changed, 12 insertions, 5 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index df42d899e41f..4d7de397481f 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -194,11 +194,16 @@ struct page {
  * routine so they can be sure the page doesn't go away from under them.
  */
 #define get_page(p)		atomic_inc(&(p)->count)
-#define put_page(p)		__free_page(p)
 #define __put_page(p)		atomic_dec(&(p)->count)
 #define put_page_testzero(p) 	atomic_dec_and_test(&(p)->count)
 #define page_count(p)		atomic_read(&(p)->count)
 #define set_page_count(p,v) 	atomic_set(&(p)->count, v)
+extern void FASTCALL(__page_cache_release(struct page *));
+#define put_page(p)					\
+	do {						\
+		if (put_page_testzero(p))		\
+			__page_cache_release(p);	\
+	} while (0)
 
 /*
  * Multiple processes may "see" the same page. E.g. for untouched
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 69e214920908..ff10783f8632 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -23,14 +23,18 @@
 #define PAGE_CACHE_ALIGN(addr)	(((addr)+PAGE_CACHE_SIZE-1)&PAGE_CACHE_MASK)
 
 #define page_cache_get(x)	get_page(x)
-extern void FASTCALL(page_cache_release(struct page *));
+
+static inline void page_cache_release(struct page *page)
+{
+	if (!PageReserved(page) && put_page_testzero(page))
+		__page_cache_release(page);
+}
 
 static inline struct page *page_cache_alloc(struct address_space *x)
 {
 	return alloc_pages(x->gfp_mask, 0);
 }
 
-
 typedef int filler_t(void *, struct page *);
 
 extern struct page * find_get_page(struct address_space *mapping,
diff --git a/include/linux/swap.h b/include/linux/swap.h
index e09e96170182..a7f1f96ff9f1 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -156,8 +156,6 @@ extern int FASTCALL(page_over_rsslimit(struct page *));
 
 /* linux/mm/swap.c */
 extern void FASTCALL(lru_cache_add(struct page *));
-extern void FASTCALL(__lru_cache_del(struct page *));
-extern void FASTCALL(lru_cache_del(struct page *));
 
 extern void FASTCALL(activate_page(struct page *));