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(gfp_t gfp);
  56 #else
  57 static inline struct page *__page_cache_alloc(gfp_t gfp)
  58 {
  59         return alloc_pages(gfp, 0);
  60 }
  61 #endif
  62
  63 static inline struct page *page_cache_alloc(struct address_space *x)
  64 {
  65         return __page_cache_alloc(mapping_gfp_mask(x));
  66 }
  67
  68 static inline struct page *page_cache_alloc_cold(struct address_space *x)
  69 {
  70         return __page_cache_alloc(mapping_gfp_mask(x)|__GFP_COLD);
  71 }
  72
  73 typedef int filler_t(void *, struct page *);
  74
  75 extern struct page * find_get_page(struct address_space *mapping,
  76                                 unsigned long index);
  77 extern struct page * find_lock_page(struct address_space *mapping,
  78                                 unsigned long index);
  79 extern struct page * find_or_create_page(struct address_space *mapping,
  80                                 unsigned long index, gfp_t gfp_mask);
  81 unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
  82                         unsigned int nr_pages, struct page **pages);
  83 unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,
  84                                unsigned int nr_pages, struct page **pages);
  85 unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
  86                         int tag, unsigned int nr_pages, struct page **pages);
  87
  88 /*
  89  * Returns locked page at given index in given cache, creating it if needed.
  90  */
  91 static inline struct page *grab_cache_page(struct address_space *mapping, unsigned long index)
  92 {
  93         return find_or_create_page(mapping, index, mapping_gfp_mask(mapping));
  94 }
  95
  96 extern struct page * grab_cache_page_nowait(struct address_space *mapping,
  97                                 unsigned long index);
  98 extern struct page * read_cache_page(struct address_space *mapping,
  99                                 unsigned long index, filler_t *filler,
 100                                 void *data);
 101 extern int read_cache_pages(struct address_space *mapping,
 102                 struct list_head *pages, filler_t *filler, void *data);
 103
 104 static inline struct page *read_mapping_page(struct address_space *mapping,
 105                                              unsigned long index, void *data)
 106 {
 107         filler_t *filler = (filler_t *)mapping->a_ops->readpage;
 108         return read_cache_page(mapping, index, filler, data);
 109 }
 110
 111 int add_to_page_cache(struct page *page, struct address_space *mapping,
 112                                 unsigned long index, gfp_t gfp_mask);
 113 int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
 114                                 unsigned long index, gfp_t gfp_mask);
 115 extern void remove_from_page_cache(struct page *page);
 116 extern void __remove_from_page_cache(struct page *page);
 117
 118 /*
 119  * Return byte-offset into filesystem object for page.
 120  */
 121 static inline loff_t page_offset(struct page *page)
 122 {
 123         return ((loff_t)page->index) << PAGE_CACHE_SHIFT;
 124 }
 125
 126 static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
 127                                         unsigned long address)
 128 {
 129         pgoff_t pgoff = (address - vma->vm_start) >> PAGE_SHIFT;
 130         pgoff += vma->vm_pgoff;
 131         return pgoff >> (PAGE_CACHE_SHIFT - PAGE_SHIFT);
 132 }
 133
 134 extern void FASTCALL(__lock_page(struct page *page));
 135 extern void FASTCALL(__lock_page_nosync(struct page *page));
 136 extern void FASTCALL(unlock_page(struct page *page));
 137
 138 /*
 139  * lock_page may only be called if we have the page's inode pinned.
 140  */
 141 static inline void lock_page(struct page *page)
 142 {
 143         might_sleep();
 144         if (TestSetPageLocked(page))
 145                 __lock_page(page);
 146 }
 147
 148 /*
 149  * lock_page_nosync should only be used if we can't pin the page's inode.
 150  * Doesn't play quite so well with block device plugging.
 151  */
 152 static inline void lock_page_nosync(struct page *page)
 153 {
 154         might_sleep();
 155         if (TestSetPageLocked(page))
 156                 __lock_page_nosync(page);
 157 }
 158
 159 /*
 160  * This is exported only for wait_on_page_locked/wait_on_page_writeback.
 161  * Never use this directly!
 162  */
 163 extern void FASTCALL(wait_on_page_bit(struct page *page, int bit_nr));
 164
 165 /*
 166  * Wait for a page to be unlocked.
 167  *
 168  * This must be called with the caller "holding" the page,
 169  * ie with increased "page->count" so that the page won't
 170  * go away during the wait..
 171  */
 172 static inline void wait_on_page_locked(struct page *page)
 173 {
 174         if (PageLocked(page))
 175                 wait_on_page_bit(page, PG_locked);
 176 }
 177
 178 /*
 179  * Wait for a page to complete writeback
 180  */
 181 static inline void wait_on_page_writeback(struct page *page)
 182 {
 183         if (PageWriteback(page))
 184                 wait_on_page_bit(page, PG_writeback);
 185 }
 186
 187 extern void end_page_writeback(struct page *page);
 188
 189 /*
 190  * Fault a userspace page into pagetables.  Return non-zero on a fault.
 191  *
 192  * This assumes that two userspace pages are always sufficient.  That's
 193  * not true if PAGE_CACHE_SIZE > PAGE_SIZE.
 194  */
 195 static inline int fault_in_pages_writeable(char __user *uaddr, int size)
 196 {
 197         int ret;
 198
 199         /*
 200          * Writing zeroes into userspace here is OK, because we know that if
 201          * the zero gets there, we'll be overwriting it.
 202          */
 203         ret = __put_user(0, uaddr);
 204         if (ret == 0) {
 205                 char __user *end = uaddr + size - 1;
 206
 207                 /*
 208                  * If the page was already mapped, this will get a cache miss
 209                  * for sure, so try to avoid doing it.
 210                  */
 211                 if (((unsigned long)uaddr & PAGE_MASK) !=
 212                                 ((unsigned long)end & PAGE_MASK))
 213                         ret = __put_user(0, end);
 214         }
 215         return ret;
 216 }
 217
 218 static inline void fault_in_pages_readable(const char __user *uaddr, int size)
 219 {
 220         volatile char c;
 221         int ret;
 222
 223         ret = __get_user(c, uaddr);
 224         if (ret == 0) {
 225                 const char __user *end = uaddr + size - 1;
 226
 227                 if (((unsigned long)uaddr & PAGE_MASK) !=
 228                                 ((unsigned long)end & PAGE_MASK))
 229                         __get_user(c, end);
 230         }
 231 }
 232
 233 #endif /* _LINUX_PAGEMAP_H */