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
23 static 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
33 static 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 */
42 static 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)
63 void release_pages(struct page **pages, int nr, int cold);
64
65 #ifdef CONFIG_NUMA
66 extern struct page *__page_cache_alloc(gfp_t gfp);
67 #else
68 static inline struct page *__page_cache_alloc(gfp_t gfp)
69 {
70 return alloc_pages(gfp, 0);
71 }
72 #endif
73
74 static inline struct page *page_cache_alloc(struct address_space *x)
75 {
76 return __page_cache_alloc(mapping_gfp_mask(x));
77 }
78
79 static 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
84 typedef int filler_t(void *, struct page *);
85
86 extern struct page * find_get_page(struct address_space *mapping,
87 pgoff_t index);
88 extern struct page * find_lock_page(struct address_space *mapping,
89 pgoff_t index);
90 extern struct page * find_or_create_page(struct address_space *mapping,
91 pgoff_t index, gfp_t gfp_mask);
92 unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
93 unsigned int nr_pages, struct page **pages);
94 unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,
95 unsigned int nr_pages, struct page **pages);
96 unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
97 int tag, unsigned int nr_pages, struct page **pages);
98
99 struct 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 */
104 static 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
110 extern struct page * grab_cache_page_nowait(struct address_space *mapping,
111 pgoff_t index);
112 extern struct page * read_cache_page_async(struct address_space *mapping,
113 pgoff_t index, filler_t *filler,
114 void *data);
115 extern struct page * read_cache_page(struct address_space *mapping,
116 pgoff_t index, filler_t *filler,
117 void *data);
118 extern int read_cache_pages(struct address_space *mapping,
119 struct list_head *pages, filler_t *filler, void *data);
120
121 static 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
129 static 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
136 int add_to_page_cache(struct page *page, struct address_space *mapping,
137 pgoff_t index, gfp_t gfp_mask);
138 int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
139 pgoff_t index, gfp_t gfp_mask);
140 extern void remove_from_page_cache(struct page *page);
141 extern void __remove_from_page_cache(struct page *page);
142
143 /*
144 * Return byte-offset into filesystem object for page.
145 */
146 static inline loff_t page_offset(struct page *page)
147 {
148 return ((loff_t)page->index) << PAGE_CACHE_SHIFT;
149 }
150
151 static 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
159 extern void __lock_page(struct page *page);
160 extern int __lock_page_killable(struct page *page);
161 extern void __lock_page_nosync(struct page *page);
162 extern void unlock_page(struct page *page);
163
164 /*
165 * lock_page may only be called if we have the page's inode pinned.
166 */
167 static 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 */
179 static 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 */
191 static 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 */
202 extern 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 */
211 static 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 */
220 static inline void wait_on_page_writeback(struct page *page)
221 {
222 if (PageWriteback(page))
223 wait_on_page_bit(page, PG_writeback);
224 }
225
226 extern 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 */
234 static 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
260 static 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
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