include/linux/rmap.h

   1 #ifndef _LINUX_RMAP_H
   2 #define _LINUX_RMAP_H
   3 /*
   4  * Declarations for Reverse Mapping functions in mm/rmap.c
   5  */
   6
   7 #include <linux/config.h>
   8 #include <linux/list.h>
   9 #include <linux/slab.h>
  10 #include <linux/mm.h>
  11 #include <linux/spinlock.h>
  12
  13 /*
  14  * The anon_vma heads a list of private "related" vmas, to scan if
  15  * an anonymous page pointing to this anon_vma needs to be unmapped:
  16  * the vmas on the list will be related by forking, or by splitting.
  17  *
  18  * Since vmas come and go as they are split and merged (particularly
  19  * in mprotect), the mapping field of an anonymous page cannot point
  20  * directly to a vma: instead it points to an anon_vma, on whose list
  21  * the related vmas can be easily linked or unlinked.
  22  *
  23  * After unlinking the last vma on the list, we must garbage collect
  24  * the anon_vma object itself: we're guaranteed no page can be
  25  * pointing to this anon_vma once its vma list is empty.
  26  */
  27 struct anon_vma {
  28         spinlock_t lock;        /* Serialize access to vma list */
  29         struct list_head head;  /* List of private "related" vmas */
  30 };
  31
  32 #ifdef CONFIG_MMU
  33
  34 extern kmem_cache_t *anon_vma_cachep;
  35
  36 static inline struct anon_vma *anon_vma_alloc(void)
  37 {
  38         return kmem_cache_alloc(anon_vma_cachep, SLAB_KERNEL);
  39 }
  40
  41 static inline void anon_vma_free(struct anon_vma *anon_vma)
  42 {
  43         kmem_cache_free(anon_vma_cachep, anon_vma);
  44 }
  45
  46 static inline void anon_vma_lock(struct vm_area_struct *vma)
  47 {
  48         struct anon_vma *anon_vma = vma->anon_vma;
  49         if (anon_vma)
  50                 spin_lock(&anon_vma->lock);
  51 }
  52
  53 static inline void anon_vma_unlock(struct vm_area_struct *vma)
  54 {
  55         struct anon_vma *anon_vma = vma->anon_vma;
  56         if (anon_vma)
  57                 spin_unlock(&anon_vma->lock);
  58 }
  59
  60 /*
  61  * anon_vma helper functions.
  62  */
  63 void anon_vma_init(void);       /* create anon_vma_cachep */
  64 int  anon_vma_prepare(struct vm_area_struct *);
  65 void __anon_vma_merge(struct vm_area_struct *, struct vm_area_struct *);
  66 void anon_vma_unlink(struct vm_area_struct *);
  67 void anon_vma_link(struct vm_area_struct *);
  68 void __anon_vma_link(struct vm_area_struct *);
  69
  70 /*
  71  * rmap interfaces called when adding or removing pte of page
  72  */
  73 void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
  74 void page_add_file_rmap(struct page *);
  75 void page_remove_rmap(struct page *);
  76
  77 /**
  78  * page_dup_rmap - duplicate pte mapping to a page
  79  * @page:       the page to add the mapping to
  80  *
  81  * For copy_page_range only: minimal extract from page_add_rmap,
  82  * avoiding unnecessary tests (already checked) so it's quicker.
  83  */
  84 static inline void page_dup_rmap(struct page *page)
  85 {
  86         atomic_inc(&page->_mapcount);
  87 }
  88
  89 /*
  90  * Called from mm/vmscan.c to handle paging out
  91  */
  92 int page_referenced(struct page *, int is_locked, int ignore_token);
  93 int try_to_unmap(struct page *);
  94
  95 /*
  96  * Called from mm/filemap_xip.c to unmap empty zero page
  97  */
  98 pte_t *page_check_address(struct page *, struct mm_struct *,
  99                                 unsigned long, spinlock_t **);
 100
 101 /*
 102  * Used by swapoff to help locate where page is expected in vma.
 103  */
 104 unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
 105
 106 #else   /* !CONFIG_MMU */
 107
 108 #define anon_vma_init()         do {} while (0)
 109 #define anon_vma_prepare(vma)   (0)
 110 #define anon_vma_link(vma)      do {} while (0)
 111
 112 #define page_referenced(page,l,i) TestClearPageReferenced(page)
 113 #define try_to_unmap(page)      SWAP_FAIL
 114
 115 #endif  /* CONFIG_MMU */
 116
 117 /*
 118  * Return values of try_to_unmap
 119  */
 120 #define SWAP_SUCCESS    0
 121 #define SWAP_AGAIN      1
 122 #define SWAP_FAIL       2
 123
 124 #endif  /* _LINUX_RMAP_H */