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
  22 static 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  */
  31 static 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)
  52 void release_pages(struct page **pages, int nr, int cold);
  53
  54 #ifdef CONFIG_NUMA
  55 extern struct page *page_cache_alloc(struct address_space *x);
  56 extern struct page *page_cache_alloc_cold(struct address_space *x);
  57 #else
  58 static inline struct page *page_cache_alloc(struct address_space *x)
  59 {
  60         return alloc_pages(mapping_gfp_mask(x), 0);
  61 }
  62
  63 static 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
  69 typedef int filler_t(void *, struct page *);
  70
  71 extern struct page * find_get_page(struct address_space *mapping,
  72                                 unsigned long index);
  73 extern struct page * find_lock_page(struct address_space *mapping,
  74                                 unsigned long index);
  75 extern __deprecated_for_modules struct page * find_trylock_page(
  76                         struct address_space *mapping, unsigned long index);
  77 extern struct page * find_or_create_page(struct address_space *mapping,
  78                                 unsigned long index, gfp_t gfp_mask);
  79 unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
  80                         unsigned int nr_pages, struct page **pages);
  81 unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,
  82                                unsigned int nr_pages, struct page **pages);
  83 unsigned 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  */
  89 static 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
  94 extern struct page * grab_cache_page_nowait(struct address_space *mapping,
  95                                 unsigned long index);
  96 extern struct page * read_cache_page(struct address_space *mapping,
  97                                 unsigned long index, filler_t *filler,
  98                                 void *data);
  99 extern int read_cache_pages(struct address_space *mapping,
 100                 struct list_head *pages, filler_t *filler, void *data);
 101
 102 static 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
 109 int add_to_page_cache(struct page *page, struct address_space *mapping,
 110                                 unsigned long index, gfp_t gfp_mask);
 111 int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
 112                                 unsigned long index, gfp_t gfp_mask);
 113 extern void remove_from_page_cache(struct page *page);
 114 extern void __remove_from_page_cache(struct page *page);
 115
 116 /*
 117  * Return byte-offset into filesystem object for page.
 118  */
 119 static inline loff_t page_offset(struct page *page)
 120 {
 121         return ((loff_t)page->index) << PAGE_CACHE_SHIFT;
 122 }
 123
 124 static 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
 132 extern void FASTCALL(__lock_page(struct page *page));
 133 extern void FASTCALL(unlock_page(struct page *page));
 134
 135 static 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  */
 146 extern 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  */
 155 static 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  */
 164 static inline void wait_on_page_writeback(struct page *page)
 165 {
 166         if (PageWriteback(page))
 167                 wait_on_page_bit(page, PG_writeback);
 168 }
 169
 170 extern 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  */
 178 static 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
 201 static 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 */