[PATCH] add page_mkwrite() vm_operations method

[pandora-kernel.git] / include / linux / mm.h

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 498ff87..3b09444 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -7,7 +7,6 @@
 
 #ifdef __KERNEL__
 
-#include <linux/config.h>
 #include <linux/gfp.h>
 #include <linux/list.h>
 #include <linux/mmzone.h>
@@ -200,6 +199,10 @@ struct vm_operations_struct {
        void (*close)(struct vm_area_struct * area);
        struct page * (*nopage)(struct vm_area_struct * area, unsigned long address, int *type);
        int (*populate)(struct vm_area_struct * area, unsigned long address, unsigned long len, pgprot_t prot, unsigned long pgoff, int nonblock);
+
+       /* notification that a previously read-only page is about to become
+        * writable, if an error is returned it will cause a SIGBUS */
+       int (*page_mkwrite)(struct vm_area_struct *vma, struct page *page);
 #ifdef CONFIG_NUMA
        int (*set_policy)(struct vm_area_struct *vma, struct mempolicy *new);
        struct mempolicy *(*get_policy)(struct vm_area_struct *vma,
@@ -229,10 +232,9 @@ struct page {
                unsigned long private;          /* Mapping-private opaque data:
                                                 * usually used for buffer_heads
                                                 * if PagePrivate set; used for
-                                                * swp_entry_t if PageSwapCache.
-                                                * When page is free, this
+                                                * swp_entry_t if PageSwapCache;
                                                 * indicates order in the buddy
-                                                * system.
+                                                * system if PG_buddy is set.
                                                 */
                struct address_space *mapping;  /* If low bit clear, points to
                                                 * inode address_space, or NULL.
@@ -286,43 +288,34 @@ struct page {
  *
  * Also, many kernel routines increase the page count before a critical
  * routine so they can be sure the page doesn't go away from under them.
- *
- * Since 2.6.6 (approx), a free page has ->_count = -1.  This is so that we
- * can use atomic_add_negative(-1, page->_count) to detect when the page
- * becomes free and so that we can also use atomic_inc_and_test to atomically
- * detect when we just tried to grab a ref on a page which some other CPU has
- * already deemed to be freeable.
- *
- * NO code should make assumptions about this internal detail!  Use the provided
- * macros which retain the old rules: page_count(page) == 0 is a free page.
  */
 
 /*
  * Drop a ref, return true if the logical refcount fell to zero (the page has
  * no users)
  */
-#define put_page_testzero(p)                           \
-       ({                                              \
-               BUG_ON(atomic_read(&(p)->_count) == -1);\
-               atomic_add_negative(-1, &(p)->_count);  \
-       })
+static inline int put_page_testzero(struct page *page)
+{
+       BUG_ON(atomic_read(&page->_count) == 0);
+       return atomic_dec_and_test(&page->_count);
+}
 
 /*
- * Grab a ref, return true if the page previously had a logical refcount of
- * zero.  ie: returns true if we just grabbed an already-deemed-to-be-free page
+ * Try to grab a ref unless the page has a refcount of zero, return false if
+ * that is the case.
  */
-#define get_page_testone(p)    atomic_inc_and_test(&(p)->_count)
-
-#define set_page_count(p,v)    atomic_set(&(p)->_count, (v) - 1)
-#define __put_page(p)          atomic_dec(&(p)->_count)
+static inline int get_page_unless_zero(struct page *page)
+{
+       return atomic_inc_not_zero(&page->_count);
+}
 
 extern void FASTCALL(__page_cache_release(struct page *));
 
 static inline int page_count(struct page *page)
 {
-       if (PageCompound(page))
+       if (unlikely(PageCompound(page)))
                page = (struct page *)page_private(page);
-       return atomic_read(&page->_count) + 1;
+       return atomic_read(&page->_count);
 }
 
 static inline void get_page(struct page *page)
@@ -332,8 +325,19 @@ static inline void get_page(struct page *page)
        atomic_inc(&page->_count);
 }
 
+/*
+ * Setup the page count before being freed into the page allocator for
+ * the first time (boot or memory hotplug)
+ */
+static inline void init_page_count(struct page *page)
+{
+       atomic_set(&page->_count, 1);
+}
+
 void put_page(struct page *page);
 
+void split_page(struct page *page, unsigned int order);
+
 /*
  * Multiple processes may "see" the same page. E.g. for untouched
  * mappings of /dev/null, all processes see the same page full of
@@ -465,10 +469,13 @@ static inline unsigned long page_zonenum(struct page *page)
 struct zone;
 extern struct zone *zone_table[];
 
+static inline int page_zone_id(struct page *page)
+{
+       return (page->flags >> ZONETABLE_PGSHIFT) & ZONETABLE_MASK;
+}
 static inline struct zone *page_zone(struct page *page)
 {
-       return zone_table[(page->flags >> ZONETABLE_PGSHIFT) &
-                       ZONETABLE_MASK];
+       return zone_table[page_zone_id(page)];
 }
 
 static inline unsigned long page_to_nid(struct page *page)
@@ -1046,7 +1053,7 @@ int in_gate_area_no_task(unsigned long addr);
 
 int drop_caches_sysctl_handler(struct ctl_table *, int, struct file *,
                                        void __user *, size_t *, loff_t *);
-int shrink_slab(unsigned long scanned, gfp_t gfp_mask,
+unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
                        unsigned long lru_pages);
 void drop_pagecache(void);
 void drop_slab(void);