LXR linux/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/list.h>
   8#include <linux/slab.h>
   9#include <linux/mm.h>
  10#include <linux/spinlock.h>
  11
  12/*
  13 * The anon_vma heads a list of private "related" vmas, to scan if
  14 * an anonymous page pointing to this anon_vma needs to be unmapped:
  15 * the vmas on the list will be related by forking, or by splitting.
  16 *
  17 * Since vmas come and go as they are split and merged (particularly
  18 * in mprotect), the mapping field of an anonymous page cannot point
  19 * directly to a vma: instead it points to an anon_vma, on whose list
  20 * the related vmas can be easily linked or unlinked.
  21 *
  22 * After unlinking the last vma on the list, we must garbage collect
  23 * the anon_vma object itself: we're guaranteed no page can be
  24 * pointing to this anon_vma once its vma list is empty.
  25 */
  26struct anon_vma {
  27        spinlock_t lock;        /* Serialize access to vma list */
  28        struct list_head head;  /* List of private "related" vmas */
  29};
  30
  31#ifdef CONFIG_MMU
  32
  33extern kmem_cache_t *anon_vma_cachep;
  34
  35static inline struct anon_vma *anon_vma_alloc(void)
  36{
  37        return kmem_cache_alloc(anon_vma_cachep, SLAB_KERNEL);
  38}
  39
  40static inline void anon_vma_free(struct anon_vma *anon_vma)
  41{
  42        kmem_cache_free(anon_vma_cachep, anon_vma);
  43}
  44
  45static inline void anon_vma_lock(struct vm_area_struct *vma)
  46{
  47        struct anon_vma *anon_vma = vma->anon_vma;
  48        if (anon_vma)
  49                spin_lock(&anon_vma->lock);
  50}
  51
  52static inline void anon_vma_unlock(struct vm_area_struct *vma)
  53{
  54        struct anon_vma *anon_vma = vma->anon_vma;
  55        if (anon_vma)
  56                spin_unlock(&anon_vma->lock);
  57}
  58
  59/*
  60 * anon_vma helper functions.
  61 */
  62void anon_vma_init(void);       /* create anon_vma_cachep */
  63int  anon_vma_prepare(struct vm_area_struct *);
  64void __anon_vma_merge(struct vm_area_struct *, struct vm_area_struct *);
  65void anon_vma_unlink(struct vm_area_struct *);
  66void anon_vma_link(struct vm_area_struct *);
  67void __anon_vma_link(struct vm_area_struct *);
  68
  69/*
  70 * rmap interfaces called when adding or removing pte of page
  71 */
  72void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
  73void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
  74void page_add_file_rmap(struct page *);
  75void 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 */
  84static 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 */
  92int page_referenced(struct page *, int is_locked);
  93int try_to_unmap(struct page *, int ignore_refs);
  94
  95/*
  96 * Called from mm/filemap_xip.c to unmap empty zero page
  97 */
  98pte_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 */
 104unsigned 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) TestClearPageReferenced(page)
 113#define try_to_unmap(page, refs) 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 */
 125