LXR linux/include/linux/pagemap.h

   1#ifndef _LINUX_PAGEMAP_H
   2#define _LINUX_PAGEMAP_H
   3
   4/*
   5 * Copyright 1995 Linus Torvalds
   6 */
   7#include <linux/mm.h>
   8#include <linux/fs.h>
   9#include <linux/list.h>
  10#include <linux/highmem.h>
  11#include <linux/compiler.h>
  12#include <asm/uaccess.h>
  13#include <linux/gfp.h>
  14
  15/*
  16 * Bits in mapping->flags.  The lower __GFP_BITS_SHIFT bits are the page
  17 * allocation mode flags.
  18 */
  19#define AS_EIO          (__GFP_BITS_SHIFT + 0)  /* IO error on async write */
  20#define AS_ENOSPC       (__GFP_BITS_SHIFT + 1)  /* ENOSPC on async write */
  21
  22static inline gfp_t mapping_gfp_mask(struct address_space * mapping)
  23{
  24        return (__force gfp_t)mapping->flags & __GFP_BITS_MASK;
  25}
  26
  27/*
  28 * This is non-atomic.  Only to be used before the mapping is activated.
  29 * Probably needs a barrier...
  30 */
  31static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
  32{
  33        m->flags = (m->flags & ~(__force unsigned long)__GFP_BITS_MASK) |
  34                                (__force unsigned long)mask;
  35}
  36
  37/*
  38 * The page cache can done in larger chunks than
  39 * one page, because it allows for more efficient
  40 * throughput (it can then be mapped into user
  41 * space in smaller chunks for same flexibility).
  42 *
  43 * Or rather, it _will_ be done in larger chunks.
  44 */
  45#define PAGE_CACHE_SHIFT        PAGE_SHIFT
  46#define PAGE_CACHE_SIZE         PAGE_SIZE
  47#define PAGE_CACHE_MASK         PAGE_MASK
  48#define PAGE_CACHE_ALIGN(addr)  (((addr)+PAGE_CACHE_SIZE-1)&PAGE_CACHE_MASK)
  49
  50#define page_cache_get(page)            get_page(page)
  51#define page_cache_release(page)        put_page(page)
  52void release_pages(struct page **pages, int nr, int cold);
  53
  54#ifdef CONFIG_NUMA
  55extern struct page *page_cache_alloc(struct address_space *x);
  56extern struct page *page_cache_alloc_cold(struct address_space *x);
  57#else
  58static inline struct page *page_cache_alloc(struct address_space *x)
  59{
  60        return alloc_pages(mapping_gfp_mask(x), 0);
  61}
  62
  63static inline struct page *page_cache_alloc_cold(struct address_space *x)
  64{
  65        return alloc_pages(mapping_gfp_mask(x)|__GFP_COLD, 0);
  66}
  67#endif
  68
  69typedef int filler_t(void *, struct page *);
  70
  71extern struct page * find_get_page(struct address_space *mapping,
  72                                unsigned long index);
  73extern struct page * find_lock_page(struct address_space *mapping,
  74                                unsigned long index);
  75extern __deprecated_for_modules struct page * find_trylock_page(
  76                        struct address_space *mapping, unsigned long index);
  77extern struct page * find_or_create_page(struct address_space *mapping,
  78                                unsigned long index, gfp_t gfp_mask);
  79unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
  80                        unsigned int nr_pages, struct page **pages);
  81unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,
  82                               unsigned int nr_pages, struct page **pages);
  83unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
  84                        int tag, unsigned int nr_pages, struct page **pages);
  85
  86/*
  87 * Returns locked page at given index in given cache, creating it if needed.
  88 */
  89static inline struct page *grab_cache_page(struct address_space *mapping, unsigned long index)
  90{
  91        return find_or_create_page(mapping, index, mapping_gfp_mask(mapping));
  92}
  93
  94extern struct page * grab_cache_page_nowait(struct address_space *mapping,
  95                                unsigned long index);
  96extern struct page * read_cache_page(struct address_space *mapping,
  97                                unsigned long index, filler_t *filler,
  98                                void *data);
  99extern int read_cache_pages(struct address_space *mapping,
 100                struct list_head *pages, filler_t *filler, void *data);
 101
 102static inline struct page *read_mapping_page(struct address_space *mapping,
 103                                             unsigned long index, void *data)
 104{
 105        filler_t *filler = (filler_t *)mapping->a_ops->readpage;
 106        return read_cache_page(mapping, index, filler, data);
 107}
 108
 109int add_to_page_cache(struct page *page, struct address_space *mapping,
 110                                unsigned long index, gfp_t gfp_mask);
 111int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
 112                                unsigned long index, gfp_t gfp_mask);
 113extern void remove_from_page_cache(struct page *page);
 114extern void __remove_from_page_cache(struct page *page);
 115
 116/*
 117 * Return byte-offset into filesystem object for page.
 118 */
 119static inline loff_t page_offset(struct page *page)
 120{
 121        return ((loff_t)page->index) << PAGE_CACHE_SHIFT;
 122}
 123
 124static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
 125                                        unsigned long address)
 126{
 127        pgoff_t pgoff = (address - vma->vm_start) >> PAGE_SHIFT;
 128        pgoff += vma->vm_pgoff;
 129        return pgoff >> (PAGE_CACHE_SHIFT - PAGE_SHIFT);
 130}
 131
 132extern void FASTCALL(__lock_page(struct page *page));
 133extern void FASTCALL(unlock_page(struct page *page));
 134
 135static inline void lock_page(struct page *page)
 136{
 137        might_sleep();
 138        if (TestSetPageLocked(page))
 139                __lock_page(page);
 140}
 141        
 142/*
 143 * This is exported only for wait_on_page_locked/wait_on_page_writeback.
 144 * Never use this directly!
 145 */
 146extern void FASTCALL(wait_on_page_bit(struct page *page, int bit_nr));
 147
 148/* 
 149 * Wait for a page to be unlocked.
 150 *
 151 * This must be called with the caller "holding" the page,
 152 * ie with increased "page->count" so that the page won't
 153 * go away during the wait..
 154 */
 155static inline void wait_on_page_locked(struct page *page)
 156{
 157        if (PageLocked(page))
 158                wait_on_page_bit(page, PG_locked);
 159}
 160
 161/* 
 162 * Wait for a page to complete writeback
 163 */
 164static inline void wait_on_page_writeback(struct page *page)
 165{
 166        if (PageWriteback(page))
 167                wait_on_page_bit(page, PG_writeback);
 168}
 169
 170extern void end_page_writeback(struct page *page);
 171
 172/*
 173 * Fault a userspace page into pagetables.  Return non-zero on a fault.
 174 *
 175 * This assumes that two userspace pages are always sufficient.  That's
 176 * not true if PAGE_CACHE_SIZE > PAGE_SIZE.
 177 */
 178static inline int fault_in_pages_writeable(char __user *uaddr, int size)
 179{
 180        int ret;
 181
 182        /*
 183         * Writing zeroes into userspace here is OK, because we know that if
 184         * the zero gets there, we'll be overwriting it.
 185         */
 186        ret = __put_user(0, uaddr);
 187        if (ret == 0) {
 188                char __user *end = uaddr + size - 1;
 189
 190                /*
 191                 * If the page was already mapped, this will get a cache miss
 192                 * for sure, so try to avoid doing it.
 193                 */
 194                if (((unsigned long)uaddr & PAGE_MASK) !=
 195                                ((unsigned long)end & PAGE_MASK))
 196                        ret = __put_user(0, end);
 197        }
 198        return ret;
 199}
 200
 201static inline void fault_in_pages_readable(const char __user *uaddr, int size)
 202{
 203        volatile char c;
 204        int ret;
 205
 206        ret = __get_user(c, uaddr);
 207        if (ret == 0) {
 208                const char __user *end = uaddr + size - 1;
 209
 210                if (((unsigned long)uaddr & PAGE_MASK) !=
 211                                ((unsigned long)end & PAGE_MASK))
 212                        __get_user(c, end);
 213        }
 214}
 215
 216#endif /* _LINUX_PAGEMAP_H */
 217