LXR linux-old/include/linux/pagemap.h

   1#ifndef _LINUX_PAGEMAP_H
   2#define _LINUX_PAGEMAP_H
   3
   4/*
   5 * Page-mapping primitive inline functions
   6 *
   7 * Copyright 1995 Linus Torvalds
   8 */
   9
  10#include <linux/mm.h>
  11#include <linux/fs.h>
  12#include <linux/list.h>
  13
  14#include <asm/system.h>
  15#include <asm/pgtable.h>
  16#include <linux/highmem.h>
  17
  18/*
  19 * The page cache can done in larger chunks than
  20 * one page, because it allows for more efficient
  21 * throughput (it can then be mapped into user
  22 * space in smaller chunks for same flexibility).
  23 *
  24 * Or rather, it _will_ be done in larger chunks.
  25 */
  26#define PAGE_CACHE_SHIFT        PAGE_SHIFT
  27#define PAGE_CACHE_SIZE         PAGE_SIZE
  28#define PAGE_CACHE_MASK         PAGE_MASK
  29#define PAGE_CACHE_ALIGN(addr)  (((addr)+PAGE_CACHE_SIZE-1)&PAGE_CACHE_MASK)
  30
  31#define page_cache_get(x)       get_page(x)
  32#define page_cache_release(x)   __free_page(x)
  33
  34static inline struct page *page_cache_alloc(struct address_space *x)
  35{
  36        return alloc_pages(x->gfp_mask, 0);
  37}
  38
  39/*
  40 * From a kernel address, get the "struct page *"
  41 */
  42#define page_cache_entry(x)     virt_to_page(x)
  43
  44extern unsigned int page_hash_bits;
  45#define PAGE_HASH_BITS (page_hash_bits)
  46#define PAGE_HASH_SIZE (1 << PAGE_HASH_BITS)
  47
  48extern unsigned long page_cache_size; /* # of pages currently in the hash table */
  49extern struct page **page_hash_table;
  50
  51extern void page_cache_init(unsigned long);
  52
  53/*
  54 * We use a power-of-two hash table to avoid a modulus,
  55 * and get a reasonable hash by knowing roughly how the
  56 * inode pointer and indexes are distributed (ie, we
  57 * roughly know which bits are "significant")
  58 *
  59 * For the time being it will work for struct address_space too (most of
  60 * them sitting inside the inodes). We might want to change it later.
  61 */
  62static inline unsigned long _page_hashfn(struct address_space * mapping, unsigned long index)
  63{
  64#define i (((unsigned long) mapping)/(sizeof(struct inode) & ~ (sizeof(struct inode) - 1)))
  65#define s(x) ((x)+((x)>>PAGE_HASH_BITS))
  66        return s(i+index) & (PAGE_HASH_SIZE-1);
  67#undef i
  68#undef s
  69}
  70
  71#define page_hash(mapping,index) (page_hash_table+_page_hashfn(mapping,index))
  72
  73extern struct page * __find_get_page(struct address_space *mapping,
  74                                unsigned long index, struct page **hash);
  75#define find_get_page(mapping, index) \
  76        __find_get_page(mapping, index, page_hash(mapping, index))
  77extern struct page * __find_lock_page (struct address_space * mapping,
  78                                unsigned long index, struct page **hash);
  79extern struct page * find_or_create_page(struct address_space *mapping,
  80                                unsigned long index, unsigned int gfp_mask);
  81
  82extern void FASTCALL(lock_page(struct page *page));
  83extern void FASTCALL(unlock_page(struct page *page));
  84#define find_lock_page(mapping, index) \
  85        __find_lock_page(mapping, index, page_hash(mapping, index))
  86extern struct page *find_trylock_page(struct address_space *, unsigned long);
  87
  88extern void add_to_page_cache(struct page * page, struct address_space *mapping, unsigned long index);
  89extern void add_to_page_cache_locked(struct page * page, struct address_space *mapping, unsigned long index);
  90extern int add_to_page_cache_unique(struct page * page, struct address_space *mapping, unsigned long index, struct page **hash);
  91
  92extern void ___wait_on_page(struct page *);
  93
  94static inline void wait_on_page(struct page * page)
  95{
  96        if (PageLocked(page))
  97                ___wait_on_page(page);
  98}
  99
 100extern void FASTCALL(wakeup_page_waiters(struct page * page));
 101
 102/*
 103 * Returns locked page at given index in given cache, creating it if needed.
 104 */
 105static inline struct page *grab_cache_page(struct address_space *mapping, unsigned long index)
 106{
 107        return find_or_create_page(mapping, index, mapping->gfp_mask);
 108}
 109
 110
 111extern struct page * grab_cache_page_nowait (struct address_space *, unsigned long);
 112
 113typedef int filler_t(void *, struct page*);
 114
 115extern struct page *read_cache_page(struct address_space *, unsigned long,
 116                                filler_t *, void *);
 117#endif
 118