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 #include <linux/bitops.h>
  15
  16 /*
  17  * Bits in mapping->flags.  The lower __GFP_BITS_SHIFT bits are the page
  18  * allocation mode flags.
  19  */
  20 #define AS_EIO          (__GFP_BITS_SHIFT + 0)  /* IO error on async write */
  21 #define AS_ENOSPC       (__GFP_BITS_SHIFT + 1)  /* ENOSPC on async write */
  22
  23 static inline void mapping_set_error(struct address_space *mapping, int error)
  24 {
  25         if (error) {
  26                 if (error == -ENOSPC)
  27                         set_bit(AS_ENOSPC, &mapping->flags);
  28                 else
  29                         set_bit(AS_EIO, &mapping->flags);
  30         }
  31 }
  32
  33 static inline gfp_t mapping_gfp_mask(struct address_space * mapping)
  34 {
  35         return (__force gfp_t)mapping->flags & __GFP_BITS_MASK;
  36 }
  37
  38 /*
  39  * This is non-atomic.  Only to be used before the mapping is activated.
  40  * Probably needs a barrier...
  41  */
  42 static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
  43 {
  44         m->flags = (m->flags & ~(__force unsigned long)__GFP_BITS_MASK) |
  45                                 (__force unsigned long)mask;
  46 }
  47
  48 /*
  49  * The page cache can done in larger chunks than
  50  * one page, because it allows for more efficient
  51  * throughput (it can then be mapped into user
  52  * space in smaller chunks for same flexibility).
  53  *
  54  * Or rather, it _will_ be done in larger chunks.
  55  */
  56 #define PAGE_CACHE_SHIFT        PAGE_SHIFT
  57 #define PAGE_CACHE_SIZE         PAGE_SIZE
  58 #define PAGE_CACHE_MASK         PAGE_MASK
  59 #define PAGE_CACHE_ALIGN(addr)  (((addr)+PAGE_CACHE_SIZE-1)&PAGE_CACHE_MASK)
  60
  61 #define page_cache_get(page)            get_page(page)
  62 #define page_cache_release(page)        put_page(page)
  63 void release_pages(struct page **pages, int nr, int cold);
  64
  65 #ifdef CONFIG_NUMA
  66 extern struct page *__page_cache_alloc(gfp_t gfp);
  67 #else
  68 static inline struct page *__page_cache_alloc(gfp_t gfp)
  69 {
  70         return alloc_pages(gfp, 0);
  71 }
  72 #endif
  73
  74 static inline struct page *page_cache_alloc(struct address_space *x)
  75 {
  76         return __page_cache_alloc(mapping_gfp_mask(x));
  77 }
  78
  79 static inline struct page *page_cache_alloc_cold(struct address_space *x)
  80 {
  81         return __page_cache_alloc(mapping_gfp_mask(x)|__GFP_COLD);
  82 }
  83
  84 typedef int filler_t(void *, struct page *);
  85
  86 extern struct page * find_get_page(struct address_space *mapping,
  87                                 pgoff_t index);
  88 extern struct page * find_lock_page(struct address_space *mapping,
  89                                 pgoff_t index);
  90 extern struct page * find_or_create_page(struct address_space *mapping,
  91                                 pgoff_t index, gfp_t gfp_mask);
  92 unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
  93                         unsigned int nr_pages, struct page **pages);
  94 unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,
  95                                unsigned int nr_pages, struct page **pages);
  96 unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
  97                         int tag, unsigned int nr_pages, struct page **pages);
  98
  99 struct page *__grab_cache_page(struct address_space *mapping, pgoff_t index);
 100
 101 /*
 102  * Returns locked page at given index in given cache, creating it if needed.
 103  */
 104 static inline struct page *grab_cache_page(struct address_space *mapping,
 105                                                                 pgoff_t index)
 106 {
 107         return find_or_create_page(mapping, index, mapping_gfp_mask(mapping));
 108 }
 109
 110 extern struct page * grab_cache_page_nowait(struct address_space *mapping,
 111                                 pgoff_t index);
 112 extern struct page * read_cache_page_async(struct address_space *mapping,
 113                                 pgoff_t index, filler_t *filler,
 114                                 void *data);
 115 extern struct page * read_cache_page(struct address_space *mapping,
 116                                 pgoff_t index, filler_t *filler,
 117                                 void *data);
 118 extern int read_cache_pages(struct address_space *mapping,
 119                 struct list_head *pages, filler_t *filler, void *data);
 120
 121 static inline struct page *read_mapping_page_async(
 122                                                 struct address_space *mapping,
 123                                                      pgoff_t index, void *data)
 124 {
 125         filler_t *filler = (filler_t *)mapping->a_ops->readpage;
 126         return read_cache_page_async(mapping, index, filler, data);
 127 }
 128
 129 static inline struct page *read_mapping_page(struct address_space *mapping,
 130                                              pgoff_t index, void *data)
 131 {
 132         filler_t *filler = (filler_t *)mapping->a_ops->readpage;
 133         return read_cache_page(mapping, index, filler, data);
 134 }
 135
 136 int add_to_page_cache(struct page *page, struct address_space *mapping,
 137                                 pgoff_t index, gfp_t gfp_mask);
 138 int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
 139                                 pgoff_t index, gfp_t gfp_mask);
 140 extern void remove_from_page_cache(struct page *page);
 141 extern void __remove_from_page_cache(struct page *page);
 142
 143 /*
 144  * Return byte-offset into filesystem object for page.
 145  */
 146 static inline loff_t page_offset(struct page *page)
 147 {
 148         return ((loff_t)page->index) << PAGE_CACHE_SHIFT;
 149 }
 150
 151 static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
 152                                         unsigned long address)
 153 {
 154         pgoff_t pgoff = (address - vma->vm_start) >> PAGE_SHIFT;
 155         pgoff += vma->vm_pgoff;
 156         return pgoff >> (PAGE_CACHE_SHIFT - PAGE_SHIFT);
 157 }
 158
 159 extern void FASTCALL(__lock_page(struct page *page));
 160 extern void FASTCALL(__lock_page_nosync(struct page *page));
 161 extern void FASTCALL(unlock_page(struct page *page));
 162
 163 /*
 164  * lock_page may only be called if we have the page's inode pinned.
 165  */
 166 static inline void lock_page(struct page *page)
 167 {
 168         might_sleep();
 169         if (TestSetPageLocked(page))
 170                 __lock_page(page);
 171 }
 172
 173 /*
 174  * lock_page_nosync should only be used if we can't pin the page's inode.
 175  * Doesn't play quite so well with block device plugging.
 176  */
 177 static inline void lock_page_nosync(struct page *page)
 178 {
 179         might_sleep();
 180         if (TestSetPageLocked(page))
 181                 __lock_page_nosync(page);
 182 }
 183
 184 /*
 185  * This is exported only for wait_on_page_locked/wait_on_page_writeback.
 186  * Never use this directly!
 187  */
 188 extern void FASTCALL(wait_on_page_bit(struct page *page, int bit_nr));
 189
 190 /*
 191  * Wait for a page to be unlocked.
 192  *
 193  * This must be called with the caller "holding" the page,
 194  * ie with increased "page->count" so that the page won't
 195  * go away during the wait..
 196  */
 197 static inline void wait_on_page_locked(struct page *page)
 198 {
 199         if (PageLocked(page))
 200                 wait_on_page_bit(page, PG_locked);
 201 }
 202
 203 /*
 204  * Wait for a page to complete writeback
 205  */
 206 static inline void wait_on_page_writeback(struct page *page)
 207 {
 208         if (PageWriteback(page))
 209                 wait_on_page_bit(page, PG_writeback);
 210 }
 211
 212 extern void end_page_writeback(struct page *page);
 213
 214 /*
 215  * Fault a userspace page into pagetables.  Return non-zero on a fault.
 216  *
 217  * This assumes that two userspace pages are always sufficient.  That's
 218  * not true if PAGE_CACHE_SIZE > PAGE_SIZE.
 219  */
 220 static inline int fault_in_pages_writeable(char __user *uaddr, int size)
 221 {
 222         int ret;
 223
 224         if (unlikely(size == 0))
 225                 return 0;
 226
 227         /*
 228          * Writing zeroes into userspace here is OK, because we know that if
 229          * the zero gets there, we'll be overwriting it.
 230          */
 231         ret = __put_user(0, uaddr);
 232         if (ret == 0) {
 233                 char __user *end = uaddr + size - 1;
 234
 235                 /*
 236                  * If the page was already mapped, this will get a cache miss
 237                  * for sure, so try to avoid doing it.
 238                  */
 239                 if (((unsigned long)uaddr & PAGE_MASK) !=
 240                                 ((unsigned long)end & PAGE_MASK))
 241                         ret = __put_user(0, end);
 242         }
 243         return ret;
 244 }
 245
 246 static inline int fault_in_pages_readable(const char __user *uaddr, int size)
 247 {
 248         volatile char c;
 249         int ret;
 250
 251         if (unlikely(size == 0))
 252                 return 0;
 253
 254         ret = __get_user(c, uaddr);
 255         if (ret == 0) {
 256                 const char __user *end = uaddr + size - 1;
 257
 258                 if (((unsigned long)uaddr & PAGE_MASK) !=
 259                                 ((unsigned long)end & PAGE_MASK))
 260                         ret = __get_user(c, end);
 261         }
 262         return ret;
 263 }
 264
 265 #endif /* _LINUX_PAGEMAP_H */