linux 2.6.16.38 w/ vs2.0.3-rc1

[linux-2.6.git] / include / linux / mm.h

diff --git a/include/linux/mm.h b/include/linux/mm.h
index e4183fa..279446e 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -285,34 +285,43 @@ 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)
  */
-static inline int put_page_testzero(struct page *page)
-{
-       BUG_ON(atomic_read(&page->_count) == 0);
-       return atomic_dec_and_test(&page->_count);
-}
+#define put_page_testzero(p)                           \
+       ({                                              \
+               BUG_ON(atomic_read(&(p)->_count) == -1);\
+               atomic_add_negative(-1, &(p)->_count);  \
+       })
 
 /*
- * Try to grab a ref unless the page has a refcount of zero, return false if
- * that is the case.
+ * 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
  */
-static inline int get_page_unless_zero(struct page *page)
-{
-       return atomic_inc_not_zero(&page->_count);
-}
+#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)
 
 extern void FASTCALL(__page_cache_release(struct page *));
 
 static inline int page_count(struct page *page)
 {
-       if (unlikely(PageCompound(page)))
+       if (PageCompound(page))
                page = (struct page *)page_private(page);
-       return atomic_read(&page->_count);
+       return atomic_read(&page->_count) + 1;
 }
 
 static inline void get_page(struct page *page)
@@ -322,19 +331,8 @@ 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
@@ -917,19 +915,7 @@ extern struct vm_area_struct *copy_vma(struct vm_area_struct **,
 extern void exit_mmap(struct mm_struct *);
 extern int may_expand_vm(struct mm_struct *mm, unsigned long npages);
 
-extern unsigned long get_unmapped_area_prot(struct file *, unsigned long, unsigned long, unsigned long, unsigned long, int);
-
-
-static inline unsigned long get_unmapped_area(struct file * file, unsigned long addr,
-               unsigned long len, unsigned long pgoff, unsigned long flags)
-{
-       return get_unmapped_area_prot(file, addr, len, pgoff, flags, 0);
-}
-
-extern int install_special_mapping(struct mm_struct *mm,
-                                  unsigned long addr, unsigned long len,
-                                  unsigned long vm_flags, pgprot_t pgprot,
-                                  struct page **pages);
+extern unsigned long get_unmapped_area(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
 
 extern unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
        unsigned long len, unsigned long prot,
@@ -981,7 +967,7 @@ unsigned long page_cache_readahead(struct address_space *mapping,
                          struct file *filp,
                          pgoff_t offset,
                          unsigned long size);
-void handle_ra_miss(struct address_space *mapping,
+void handle_ra_miss(struct address_space *mapping, 
                    struct file_ra_state *ra, pgoff_t offset);
 unsigned long max_sane_readahead(unsigned long nr);
 
@@ -1059,7 +1045,7 @@ 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 *);
-unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
+int shrink_slab(unsigned long scanned, gfp_t gfp_mask,
                        unsigned long lru_pages);
 void drop_pagecache(void);
 void drop_slab(void);