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                                 unsigned long index);
  88 extern struct page * find_lock_page(struct address_space *mapping,
  89                                 unsigned long index);
  90 extern struct page * find_or_create_page(struct address_space *mapping,
  91                                 unsigned long 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 /*
 100  * Returns locked page at given index in given cache, creating it if needed.
 101  */
 102 static inline struct page *grab_cache_page(struct address_space *mapping, unsigned long index)
 103 {
 104         return find_or_create_page(mapping, index, mapping_gfp_mask(mapping));
 105 }
 106
 107 extern struct page * grab_cache_page_nowait(struct address_space *mapping,
 108                                 unsigned long index);
 109 extern struct page * read_cache_page_async(struct address_space *mapping,
 110                                 unsigned long index, filler_t *filler,
 111                                 void *data);
 112 extern struct page * read_cache_page(struct address_space *mapping,
 113                                 unsigned long index, filler_t *filler,
 114                                 void *data);
 115 extern int read_cache_pages(struct address_space *mapping,
 116                 struct list_head *pages, filler_t *filler, void *data);
 117
 118 static inline struct page *read_mapping_page_async(
 119                                                 struct address_space *mapping,
 120                                              unsigned long index, void *data)
 121 {
 122         filler_t *filler = (filler_t *)mapping->a_ops->readpage;
 123         return read_cache_page_async(mapping, index, filler, data);
 124 }
 125
 126 static inline struct page *read_mapping_page(struct address_space *mapping,
 127                                              unsigned long index, void *data)
 128 {
 129         filler_t *filler = (filler_t *)mapping->a_ops->readpage;
 130         return read_cache_page(mapping, index, filler, data);
 131 }
 132
 133 int add_to_page_cache(struct page *page, struct address_space *mapping,
 134                                 unsigned long index, gfp_t gfp_mask);
 135 int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
 136                                 unsigned long index, gfp_t gfp_mask);
 137 extern void remove_from_page_cache(struct page *page);
 138 extern void __remove_from_page_cache(struct page *page);
 139
 140 /*
 141  * Return byte-offset into filesystem object for page.
 142  */
 143 static inline loff_t page_offset(struct page *page)
 144 {
 145         return ((loff_t)page->index) << PAGE_CACHE_SHIFT;
 146 }
 147
 148 static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
 149                                         unsigned long address)
 150 {
 151         pgoff_t pgoff = (address - vma->vm_start) >> PAGE_SHIFT;
 152         pgoff += vma->vm_pgoff;
 153         return pgoff >> (PAGE_CACHE_SHIFT - PAGE_SHIFT);
 154 }
 155
 156 extern void FASTCALL(__lock_page(struct page *page));
 157 extern void FASTCALL(__lock_page_nosync(struct page *page));
 158 extern void FASTCALL(unlock_page(struct page *page));
 159
 160 /*
 161  * lock_page may only be called if we have the page's inode pinned.
 162  */
 163 static inline void lock_page(struct page *page)
 164 {
 165         might_sleep();
 166         if (TestSetPageLocked(page))
 167                 __lock_page(page);
 168 }
 169
 170 /*
 171  * lock_page_nosync should only be used if we can't pin the page's inode.
 172  * Doesn't play quite so well with block device plugging.
 173  */
 174 static inline void lock_page_nosync(struct page *page)
 175 {
 176         might_sleep();
 177         if (TestSetPageLocked(page))
 178                 __lock_page_nosync(page);
 179 }
 180
 181 /*
 182  * This is exported only for wait_on_page_locked/wait_on_page_writeback.
 183  * Never use this directly!
 184  */
 185 extern void FASTCALL(wait_on_page_bit(struct page *page, int bit_nr));
 186
 187 /*
 188  * Wait for a page to be unlocked.
 189  *
 190  * This must be called with the caller "holding" the page,
 191  * ie with increased "page->count" so that the page won't
 192  * go away during the wait..
 193  */
 194 static inline void wait_on_page_locked(struct page *page)
 195 {
 196         if (PageLocked(page))
 197                 wait_on_page_bit(page, PG_locked);
 198 }
 199
 200 /*
 201  * Wait for a page to complete writeback
 202  */
 203 static inline void wait_on_page_writeback(struct page *page)
 204 {
 205         if (PageWriteback(page))
 206                 wait_on_page_bit(page, PG_writeback);
 207 }
 208
 209 extern void end_page_writeback(struct page *page);
 210
 211 /*
 212  * Fault a userspace page into pagetables.  Return non-zero on a fault.
 213  *
 214  * This assumes that two userspace pages are always sufficient.  That's
 215  * not true if PAGE_CACHE_SIZE > PAGE_SIZE.
 216  */
 217 static inline int fault_in_pages_writeable(char __user *uaddr, int size)
 218 {
 219         int ret;
 220
 221         /*
 222          * Writing zeroes into userspace here is OK, because we know that if
 223          * the zero gets there, we'll be overwriting it.
 224          */
 225         ret = __put_user(0, uaddr);
 226         if (ret == 0) {
 227                 char __user *end = uaddr + size - 1;
 228
 229                 /*
 230                  * If the page was already mapped, this will get a cache miss
 231                  * for sure, so try to avoid doing it.
 232                  */
 233                 if (((unsigned long)uaddr & PAGE_MASK) !=
 234                                 ((unsigned long)end & PAGE_MASK))
 235                         ret = __put_user(0, end);
 236         }
 237         return ret;
 238 }
 239
 240 static inline void fault_in_pages_readable(const char __user *uaddr, int size)
 241 {
 242         volatile char c;
 243         int ret;
 244
 245         ret = __get_user(c, uaddr);
 246         if (ret == 0) {
 247                 const char __user *end = uaddr + size - 1;
 248
 249                 if (((unsigned long)uaddr & PAGE_MASK) !=
 250                                 ((unsigned long)end & PAGE_MASK))
 251                         __get_user(c, end);
 252         }
 253 }
 254
 255 #endif /* _LINUX_PAGEMAP_H */