1 #ifndef _LINUX_PAGEMAP_H
2 #define _LINUX_PAGEMAP_H
5 * Copyright 1995 Linus Torvalds
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>
16 * Bits in mapping->flags. The lower __GFP_BITS_SHIFT bits are the page
17 * allocation mode flags.
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 */
22 static inline gfp_t mapping_gfp_mask(struct address_space * mapping)
24 return (__force gfp_t)mapping->flags & __GFP_BITS_MASK;
28 * This is non-atomic. Only to be used before the mapping is activated.
29 * Probably needs a barrier...
31 static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
33 m->flags = (m->flags & ~(__force unsigned long)__GFP_BITS_MASK) |
34 (__force unsigned long)mask;
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).
43 * Or rather, it _will_ be done in larger chunks.
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)
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);
55 extern struct page *__page_cache_alloc(gfp_t gfp);
57 static inline struct page *__page_cache_alloc(gfp_t gfp)
59 return alloc_pages(gfp, 0);
63 static inline struct page *page_cache_alloc(struct address_space *x)
65 return __page_cache_alloc(mapping_gfp_mask(x));
68 static inline struct page *page_cache_alloc_cold(struct address_space *x)
70 return __page_cache_alloc(mapping_gfp_mask(x)|__GFP_COLD);
73 typedef int filler_t(void *, struct page *);
75 extern struct page * find_get_page(struct address_space *mapping,
77 extern struct page * find_lock_page(struct address_space *mapping,
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);
89 * Returns locked page at given index in given cache, creating it if needed.
91 static inline struct page *grab_cache_page(struct address_space *mapping, unsigned long index)
93 return find_or_create_page(mapping, index, mapping_gfp_mask(mapping));
96 extern struct page * grab_cache_page_nowait(struct address_space *mapping,
98 extern struct page * read_cache_page_async(struct address_space *mapping,
99 unsigned long index, filler_t *filler,
101 extern struct page * read_cache_page(struct address_space *mapping,
102 unsigned long index, filler_t *filler,
104 extern int read_cache_pages(struct address_space *mapping,
105 struct list_head *pages, filler_t *filler, void *data);
107 static inline struct page *read_mapping_page_async(
108 struct address_space *mapping,
109 unsigned long index, void *data)
111 filler_t *filler = (filler_t *)mapping->a_ops->readpage;
112 return read_cache_page_async(mapping, index, filler, data);
115 static inline struct page *read_mapping_page(struct address_space *mapping,
116 unsigned long index, void *data)
118 filler_t *filler = (filler_t *)mapping->a_ops->readpage;
119 return read_cache_page(mapping, index, filler, data);
122 int add_to_page_cache(struct page *page, struct address_space *mapping,
123 unsigned long index, gfp_t gfp_mask);
124 int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
125 unsigned long index, gfp_t gfp_mask);
126 extern void remove_from_page_cache(struct page *page);
127 extern void __remove_from_page_cache(struct page *page);
130 * Return byte-offset into filesystem object for page.
132 static inline loff_t page_offset(struct page *page)
134 return ((loff_t)page->index) << PAGE_CACHE_SHIFT;
137 static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
138 unsigned long address)
140 pgoff_t pgoff = (address - vma->vm_start) >> PAGE_SHIFT;
141 pgoff += vma->vm_pgoff;
142 return pgoff >> (PAGE_CACHE_SHIFT - PAGE_SHIFT);
145 extern void FASTCALL(__lock_page(struct page *page));
146 extern void FASTCALL(__lock_page_nosync(struct page *page));
147 extern void FASTCALL(unlock_page(struct page *page));
150 * lock_page may only be called if we have the page's inode pinned.
152 static inline void lock_page(struct page *page)
155 if (TestSetPageLocked(page))
160 * lock_page_nosync should only be used if we can't pin the page's inode.
161 * Doesn't play quite so well with block device plugging.
163 static inline void lock_page_nosync(struct page *page)
166 if (TestSetPageLocked(page))
167 __lock_page_nosync(page);
171 * This is exported only for wait_on_page_locked/wait_on_page_writeback.
172 * Never use this directly!
174 extern void FASTCALL(wait_on_page_bit(struct page *page, int bit_nr));
177 * Wait for a page to be unlocked.
179 * This must be called with the caller "holding" the page,
180 * ie with increased "page->count" so that the page won't
181 * go away during the wait..
183 static inline void wait_on_page_locked(struct page *page)
185 if (PageLocked(page))
186 wait_on_page_bit(page, PG_locked);
190 * Wait for a page to complete writeback
192 static inline void wait_on_page_writeback(struct page *page)
194 if (PageWriteback(page))
195 wait_on_page_bit(page, PG_writeback);
198 extern void end_page_writeback(struct page *page);
201 * Fault a userspace page into pagetables. Return non-zero on a fault.
203 * This assumes that two userspace pages are always sufficient. That's
204 * not true if PAGE_CACHE_SIZE > PAGE_SIZE.
206 static inline int fault_in_pages_writeable(char __user *uaddr, int size)
211 * Writing zeroes into userspace here is OK, because we know that if
212 * the zero gets there, we'll be overwriting it.
214 ret = __put_user(0, uaddr);
216 char __user *end = uaddr + size - 1;
219 * If the page was already mapped, this will get a cache miss
220 * for sure, so try to avoid doing it.
222 if (((unsigned long)uaddr & PAGE_MASK) !=
223 ((unsigned long)end & PAGE_MASK))
224 ret = __put_user(0, end);
229 static inline void fault_in_pages_readable(const char __user *uaddr, int size)
234 ret = __get_user(c, uaddr);
236 const char __user *end = uaddr + size - 1;
238 if (((unsigned long)uaddr & PAGE_MASK) !=
239 ((unsigned long)end & PAGE_MASK))
244 #endif /* _LINUX_PAGEMAP_H */