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#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
  23static 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
  33static 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 */
  42static 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)
  63void release_pages(struct page **pages, int nr, int cold);
  64
  65#ifdef CONFIG_NUMA
  66extern struct page *__page_cache_alloc(gfp_t gfp);
  67#else
  68static inline struct page *__page_cache_alloc(gfp_t gfp)
  69{
  70        return alloc_pages(gfp, 0);
  71}
  72#endif
  73
  74static inline struct page *page_cache_alloc(struct address_space *x)
  75{
  76        return __page_cache_alloc(mapping_gfp_mask(x));
  77}
  78
  79static 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
  84typedef int filler_t(void *, struct page *);
  85
  86extern struct page * find_get_page(struct address_space *mapping,
  87                                pgoff_t index);
  88extern struct page * find_lock_page(struct address_space *mapping,
  89                                pgoff_t index);
  90extern struct page * find_or_create_page(struct address_space *mapping,
  91                                pgoff_t index, gfp_t gfp_mask);
  92unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
  93                        unsigned int nr_pages, struct page **pages);
  94unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,
  95                               unsigned int nr_pages, struct page **pages);
  96unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
  97                        int tag, unsigned int nr_pages, struct page **pages);
  98
  99struct 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 */
 104static 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
 110extern struct page * grab_cache_page_nowait(struct address_space *mapping,
 111                                pgoff_t index);
 112extern struct page * read_cache_page_async(struct address_space *mapping,
 113                                pgoff_t index, filler_t *filler,
 114                                void *data);
 115extern struct page * read_cache_page(struct address_space *mapping,
 116                                pgoff_t index, filler_t *filler,
 117                                void *data);
 118extern int read_cache_pages(struct address_space *mapping,
 119                struct list_head *pages, filler_t *filler, void *data);
 120
 121static 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
 129static 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
 136int add_to_page_cache(struct page *page, struct address_space *mapping,
 137                                pgoff_t index, gfp_t gfp_mask);
 138int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
 139                                pgoff_t index, gfp_t gfp_mask);
 140extern void remove_from_page_cache(struct page *page);
 141extern void __remove_from_page_cache(struct page *page);
 142
 143/*
 144 * Return byte-offset into filesystem object for page.
 145 */
 146static inline loff_t page_offset(struct page *page)
 147{
 148        return ((loff_t)page->index) << PAGE_CACHE_SHIFT;
 149}
 150
 151static 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
 159extern void __lock_page(struct page *page);
 160extern int __lock_page_killable(struct page *page);
 161extern void __lock_page_nosync(struct page *page);
 162extern void unlock_page(struct page *page);
 163
 164/*
 165 * lock_page may only be called if we have the page's inode pinned.
 166 */
 167static inline void lock_page(struct page *page)
 168{
 169        might_sleep();
 170        if (TestSetPageLocked(page))
 171                __lock_page(page);
 172}
 173
 174/*
 175 * lock_page_killable is like lock_page but can be interrupted by fatal
 176 * signals.  It returns 0 if it locked the page and -EINTR if it was
 177 * killed while waiting.
 178 */
 179static inline int lock_page_killable(struct page *page)
 180{
 181        might_sleep();
 182        if (TestSetPageLocked(page))
 183                return __lock_page_killable(page);
 184        return 0;
 185}
 186
 187/*
 188 * lock_page_nosync should only be used if we can't pin the page's inode.
 189 * Doesn't play quite so well with block device plugging.
 190 */
 191static inline void lock_page_nosync(struct page *page)
 192{
 193        might_sleep();
 194        if (TestSetPageLocked(page))
 195                __lock_page_nosync(page);
 196}
 197        
 198/*
 199 * This is exported only for wait_on_page_locked/wait_on_page_writeback.
 200 * Never use this directly!
 201 */
 202extern void wait_on_page_bit(struct page *page, int bit_nr);
 203
 204/* 
 205 * Wait for a page to be unlocked.
 206 *
 207 * This must be called with the caller "holding" the page,
 208 * ie with increased "page->count" so that the page won't
 209 * go away during the wait..
 210 */
 211static inline void wait_on_page_locked(struct page *page)
 212{
 213        if (PageLocked(page))
 214                wait_on_page_bit(page, PG_locked);
 215}
 216
 217/* 
 218 * Wait for a page to complete writeback
 219 */
 220static inline void wait_on_page_writeback(struct page *page)
 221{
 222        if (PageWriteback(page))
 223                wait_on_page_bit(page, PG_writeback);
 224}
 225
 226extern void end_page_writeback(struct page *page);
 227
 228/*
 229 * Fault a userspace page into pagetables.  Return non-zero on a fault.
 230 *
 231 * This assumes that two userspace pages are always sufficient.  That's
 232 * not true if PAGE_CACHE_SIZE > PAGE_SIZE.
 233 */
 234static inline int fault_in_pages_writeable(char __user *uaddr, int size)
 235{
 236        int ret;
 237
 238        if (unlikely(size == 0))
 239                return 0;
 240
 241        /*
 242         * Writing zeroes into userspace here is OK, because we know that if
 243         * the zero gets there, we'll be overwriting it.
 244         */
 245        ret = __put_user(0, uaddr);
 246        if (ret == 0) {
 247                char __user *end = uaddr + size - 1;
 248
 249                /*
 250                 * If the page was already mapped, this will get a cache miss
 251                 * for sure, so try to avoid doing it.
 252                 */
 253                if (((unsigned long)uaddr & PAGE_MASK) !=
 254                                ((unsigned long)end & PAGE_MASK))
 255                        ret = __put_user(0, end);
 256        }
 257        return ret;
 258}
 259
 260static inline int fault_in_pages_readable(const char __user *uaddr, int size)
 261{
 262        volatile char c;
 263        int ret;
 264
 265        if (unlikely(size == 0))
 266                return 0;
 267
 268        ret = __get_user(c, uaddr);
 269        if (ret == 0) {
 270                const char __user *end = uaddr + size - 1;
 271
 272                if (((unsigned long)uaddr & PAGE_MASK) !=
 273                                ((unsigned long)end & PAGE_MASK))
 274                        ret = __get_user(c, end);
 275        }
 276        return ret;
 277}
 278
 279#endif /* _LINUX_PAGEMAP_H */
 280