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                                unsigned long index);
  88extern struct page * find_lock_page(struct address_space *mapping,
  89                                unsigned long index);
  90extern struct page * find_or_create_page(struct address_space *mapping,
  91                                unsigned long 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
  99/*
 100 * Returns locked page at given index in given cache, creating it if needed.
 101 */
 102static 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
 107extern struct page * grab_cache_page_nowait(struct address_space *mapping,
 108                                unsigned long index);
 109extern struct page * read_cache_page_async(struct address_space *mapping,
 110                                unsigned long index, filler_t *filler,
 111                                void *data);
 112extern struct page * read_cache_page(struct address_space *mapping,
 113                                unsigned long index, filler_t *filler,
 114                                void *data);
 115extern int read_cache_pages(struct address_space *mapping,
 116                struct list_head *pages, filler_t *filler, void *data);
 117
 118static 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
 126static 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
 133int add_to_page_cache(struct page *page, struct address_space *mapping,
 134                                unsigned long index, gfp_t gfp_mask);
 135int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
 136                                unsigned long index, gfp_t gfp_mask);
 137extern void remove_from_page_cache(struct page *page);
 138extern void __remove_from_page_cache(struct page *page);
 139
 140/*
 141 * Return byte-offset into filesystem object for page.
 142 */
 143static inline loff_t page_offset(struct page *page)
 144{
 145        return ((loff_t)page->index) << PAGE_CACHE_SHIFT;
 146}
 147
 148static 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
 156extern void FASTCALL(__lock_page(struct page *page));
 157extern void FASTCALL(__lock_page_nosync(struct page *page));
 158extern 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 */
 163static 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 */
 174static 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 */
 185extern 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 */
 194static 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 */
 203static inline void wait_on_page_writeback(struct page *page)
 204{
 205        if (PageWriteback(page))
 206                wait_on_page_bit(page, PG_writeback);
 207}
 208
 209extern 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 */
 217static 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
 240static 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 */
 256