root/include/linux/rmap.h

INCLUDED FROM

DEFINITIONS

1. anon_vma_alloc
2. anon_vma_free
3. anon_vma_lock
4. anon_vma_unlock
5. page_dup_rmap
6. page_mkclean

#ifndef _LINUX_RMAP_H
#define _LINUX_RMAP_H
/*
 * Declarations for Reverse Mapping functions in mm/rmap.c
 */

#include <linux/list.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/spinlock.h>
#include <linux/memcontrol.h>

/*
 * The anon_vma heads a list of private "related" vmas, to scan if
 * an anonymous page pointing to this anon_vma needs to be unmapped:
 * the vmas on the list will be related by forking, or by splitting.
 *
 * Since vmas come and go as they are split and merged (particularly
 * in mprotect), the mapping field of an anonymous page cannot point
 * directly to a vma: instead it points to an anon_vma, on whose list
 * the related vmas can be easily linked or unlinked.
 *
 * After unlinking the last vma on the list, we must garbage collect
 * the anon_vma object itself: we're guaranteed no page can be
 * pointing to this anon_vma once its vma list is empty.
 */
struct anon_vma {
        spinlock_t lock;        /* Serialize access to vma list */
        /*
         * NOTE: the LSB of the head.next is set by
         * mm_take_all_locks() _after_ taking the above lock. So the
         * head must only be read/written after taking the above lock
         * to be sure to see a valid next pointer. The LSB bit itself
         * is serialized by a system wide lock only visible to
         * mm_take_all_locks() (mm_all_locks_mutex).
         */
        struct list_head head;  /* List of private "related" vmas */
};

#ifdef CONFIG_MMU

extern struct kmem_cache *anon_vma_cachep;

static inline struct anon_vma *anon_vma_alloc(void)
{
        return kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL);
}

static inline void anon_vma_free(struct anon_vma *anon_vma)
{
        kmem_cache_free(anon_vma_cachep, anon_vma);
}

static inline void anon_vma_lock(struct vm_area_struct *vma)
{
        struct anon_vma *anon_vma = vma->anon_vma;
        if (anon_vma)
                spin_lock(&anon_vma->lock);
}

static inline void anon_vma_unlock(struct vm_area_struct *vma)
{
        struct anon_vma *anon_vma = vma->anon_vma;
        if (anon_vma)
                spin_unlock(&anon_vma->lock);
}

/*
 * anon_vma helper functions.
 */
void anon_vma_init(void);       /* create anon_vma_cachep */
int  anon_vma_prepare(struct vm_area_struct *);
void __anon_vma_merge(struct vm_area_struct *, struct vm_area_struct *);
void anon_vma_unlink(struct vm_area_struct *);
void anon_vma_link(struct vm_area_struct *);
void __anon_vma_link(struct vm_area_struct *);

/*
 * rmap interfaces called when adding or removing pte of page
 */
void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
void page_add_file_rmap(struct page *);
void page_remove_rmap(struct page *, struct vm_area_struct *);

#ifdef CONFIG_DEBUG_VM
void page_dup_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address);
#else
static inline void page_dup_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address)
{
        atomic_inc(&page->_mapcount);
}
#endif

/*
 * Called from mm/vmscan.c to handle paging out
 */
int page_referenced(struct page *, int is_locked, struct mem_cgroup *cnt);
int try_to_unmap(struct page *, int ignore_refs);

/*
 * Called from mm/filemap_xip.c to unmap empty zero page
 */
pte_t *page_check_address(struct page *, struct mm_struct *,
                                unsigned long, spinlock_t **, int);

/*
 * Used by swapoff to help locate where page is expected in vma.
 */
unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);

/*
 * Cleans the PTEs of shared mappings.
 * (and since clean PTEs should also be readonly, write protects them too)
 *
 * returns the number of cleaned PTEs.
 */
int page_mkclean(struct page *);

#else   /* !CONFIG_MMU */

#define anon_vma_init()         do {} while (0)
#define anon_vma_prepare(vma)   (0)
#define anon_vma_link(vma)      do {} while (0)

#define page_referenced(page,l,cnt) TestClearPageReferenced(page)
#define try_to_unmap(page, refs) SWAP_FAIL

static inline int page_mkclean(struct page *page)
{
        return 0;
}


#endif  /* CONFIG_MMU */

/*
 * Return values of try_to_unmap
 */
#define SWAP_SUCCESS    0
#define SWAP_AGAIN      1
#define SWAP_FAIL       2

#endif  /* _LINUX_RMAP_H */