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/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 */
  27struct 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
  34extern kmem_cache_t *anon_vma_cachep;
  35
  36static inline struct anon_vma *anon_vma_alloc(void)
  37{
  38        return kmem_cache_alloc(anon_vma_cachep, SLAB_KERNEL);
  39}
  40
  41static inline void anon_vma_free(struct anon_vma *anon_vma)
  42{
  43        kmem_cache_free(anon_vma_cachep, anon_vma);
  44}
  45
  46static 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
  53static 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 */
  63void anon_vma_init(void);       /* create anon_vma_cachep */
  64int  anon_vma_prepare(struct vm_area_struct *);
  65void __anon_vma_merge(struct vm_area_struct *, struct vm_area_struct *);
  66void anon_vma_unlink(struct vm_area_struct *);
  67void anon_vma_link(struct vm_area_struct *);
  68void __anon_vma_link(struct vm_area_struct *);
  69
  70/*
  71 * rmap interfaces called when adding or removing pte of page
  72 */
  73void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
  74void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
  75void page_add_file_rmap(struct page *);
  76void page_remove_rmap(struct page *);
  77
  78/**
  79 * page_dup_rmap - duplicate pte mapping to a page
  80 * @page:       the page to add the mapping to
  81 *
  82 * For copy_page_range only: minimal extract from page_add_rmap,
  83 * avoiding unnecessary tests (already checked) so it's quicker.
  84 */
  85static inline void page_dup_rmap(struct page *page)
  86{
  87        atomic_inc(&page->_mapcount);
  88}
  89
  90/*
  91 * Called from mm/vmscan.c to handle paging out
  92 */
  93int page_referenced(struct page *, int is_locked);
  94int try_to_unmap(struct page *, int ignore_refs);
  95void remove_from_swap(struct page *page);
  96
  97/*
  98 * Called from mm/filemap_xip.c to unmap empty zero page
  99 */
 100pte_t *page_check_address(struct page *, struct mm_struct *,
 101                                unsigned long, spinlock_t **);
 102
 103/*
 104 * Used by swapoff to help locate where page is expected in vma.
 105 */
 106unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
 107
 108#else   /* !CONFIG_MMU */
 109
 110#define anon_vma_init()         do {} while (0)
 111#define anon_vma_prepare(vma)   (0)
 112#define anon_vma_link(vma)      do {} while (0)
 113
 114#define page_referenced(page,l) TestClearPageReferenced(page)
 115#define try_to_unmap(page, refs) SWAP_FAIL
 116
 117#endif  /* CONFIG_MMU */
 118
 119/*
 120 * Return values of try_to_unmap
 121 */
 122#define SWAP_SUCCESS    0
 123#define SWAP_AGAIN      1
 124#define SWAP_FAIL       2
 125
 126#endif  /* _LINUX_RMAP_H */
 127