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1da177e4 LT |
1 | /* |
2 | * include/linux/buffer_head.h | |
3 | * | |
4 | * Everything to do with buffer_heads. | |
5 | */ | |
6 | ||
7 | #ifndef _LINUX_BUFFER_HEAD_H | |
8 | #define _LINUX_BUFFER_HEAD_H | |
9 | ||
10 | #include <linux/types.h> | |
11 | #include <linux/fs.h> | |
12 | #include <linux/linkage.h> | |
13 | #include <linux/pagemap.h> | |
14 | #include <linux/wait.h> | |
15 | #include <asm/atomic.h> | |
16 | ||
17 | enum bh_state_bits { | |
18 | BH_Uptodate, /* Contains valid data */ | |
19 | BH_Dirty, /* Is dirty */ | |
20 | BH_Lock, /* Is locked */ | |
21 | BH_Req, /* Has been submitted for I/O */ | |
22 | ||
23 | BH_Mapped, /* Has a disk mapping */ | |
24 | BH_New, /* Disk mapping was newly created by get_block */ | |
25 | BH_Async_Read, /* Is under end_buffer_async_read I/O */ | |
26 | BH_Async_Write, /* Is under end_buffer_async_write I/O */ | |
27 | BH_Delay, /* Buffer is not yet allocated on disk */ | |
28 | BH_Boundary, /* Block is followed by a discontiguity */ | |
29 | BH_Write_EIO, /* I/O error on write */ | |
30 | BH_Ordered, /* ordered write */ | |
31 | BH_Eopnotsupp, /* operation not supported (barrier) */ | |
32 | ||
33 | BH_PrivateStart,/* not a state bit, but the first bit available | |
34 | * for private allocation by other entities | |
35 | */ | |
36 | }; | |
37 | ||
38 | #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512) | |
39 | ||
40 | struct page; | |
41 | struct buffer_head; | |
42 | struct address_space; | |
43 | typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate); | |
44 | ||
45 | /* | |
46 | * Keep related fields in common cachelines. The most commonly accessed | |
47 | * field (b_state) goes at the start so the compiler does not generate | |
48 | * indexed addressing for it. | |
49 | */ | |
50 | struct buffer_head { | |
51 | /* First cache line: */ | |
52 | unsigned long b_state; /* buffer state bitmap (see above) */ | |
53 | struct buffer_head *b_this_page;/* circular list of page's buffers */ | |
54 | struct page *b_page; /* the page this bh is mapped to */ | |
55 | atomic_t b_count; /* users using this block */ | |
56 | u32 b_size; /* block size */ | |
57 | ||
58 | sector_t b_blocknr; /* block number */ | |
59 | char *b_data; /* pointer to data block */ | |
60 | ||
61 | struct block_device *b_bdev; | |
62 | bh_end_io_t *b_end_io; /* I/O completion */ | |
63 | void *b_private; /* reserved for b_end_io */ | |
64 | struct list_head b_assoc_buffers; /* associated with another mapping */ | |
65 | }; | |
66 | ||
67 | /* | |
68 | * macro tricks to expand the set_buffer_foo(), clear_buffer_foo() | |
69 | * and buffer_foo() functions. | |
70 | */ | |
71 | #define BUFFER_FNS(bit, name) \ | |
72 | static inline void set_buffer_##name(struct buffer_head *bh) \ | |
73 | { \ | |
74 | set_bit(BH_##bit, &(bh)->b_state); \ | |
75 | } \ | |
76 | static inline void clear_buffer_##name(struct buffer_head *bh) \ | |
77 | { \ | |
78 | clear_bit(BH_##bit, &(bh)->b_state); \ | |
79 | } \ | |
80 | static inline int buffer_##name(const struct buffer_head *bh) \ | |
81 | { \ | |
82 | return test_bit(BH_##bit, &(bh)->b_state); \ | |
83 | } | |
84 | ||
85 | /* | |
86 | * test_set_buffer_foo() and test_clear_buffer_foo() | |
87 | */ | |
88 | #define TAS_BUFFER_FNS(bit, name) \ | |
89 | static inline int test_set_buffer_##name(struct buffer_head *bh) \ | |
90 | { \ | |
91 | return test_and_set_bit(BH_##bit, &(bh)->b_state); \ | |
92 | } \ | |
93 | static inline int test_clear_buffer_##name(struct buffer_head *bh) \ | |
94 | { \ | |
95 | return test_and_clear_bit(BH_##bit, &(bh)->b_state); \ | |
96 | } \ | |
97 | ||
98 | /* | |
99 | * Emit the buffer bitops functions. Note that there are also functions | |
100 | * of the form "mark_buffer_foo()". These are higher-level functions which | |
101 | * do something in addition to setting a b_state bit. | |
102 | */ | |
103 | BUFFER_FNS(Uptodate, uptodate) | |
104 | BUFFER_FNS(Dirty, dirty) | |
105 | TAS_BUFFER_FNS(Dirty, dirty) | |
106 | BUFFER_FNS(Lock, locked) | |
107 | TAS_BUFFER_FNS(Lock, locked) | |
108 | BUFFER_FNS(Req, req) | |
109 | TAS_BUFFER_FNS(Req, req) | |
110 | BUFFER_FNS(Mapped, mapped) | |
111 | BUFFER_FNS(New, new) | |
112 | BUFFER_FNS(Async_Read, async_read) | |
113 | BUFFER_FNS(Async_Write, async_write) | |
114 | BUFFER_FNS(Delay, delay) | |
115 | BUFFER_FNS(Boundary, boundary) | |
116 | BUFFER_FNS(Write_EIO, write_io_error) | |
117 | BUFFER_FNS(Ordered, ordered) | |
118 | BUFFER_FNS(Eopnotsupp, eopnotsupp) | |
119 | ||
120 | #define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK) | |
121 | #define touch_buffer(bh) mark_page_accessed(bh->b_page) | |
122 | ||
123 | /* If we *know* page->private refers to buffer_heads */ | |
124 | #define page_buffers(page) \ | |
125 | ({ \ | |
126 | BUG_ON(!PagePrivate(page)); \ | |
127 | ((struct buffer_head *)(page)->private); \ | |
128 | }) | |
129 | #define page_has_buffers(page) PagePrivate(page) | |
130 | ||
131 | /* | |
132 | * Declarations | |
133 | */ | |
134 | ||
135 | void FASTCALL(mark_buffer_dirty(struct buffer_head *bh)); | |
136 | void init_buffer(struct buffer_head *, bh_end_io_t *, void *); | |
137 | void set_bh_page(struct buffer_head *bh, | |
138 | struct page *page, unsigned long offset); | |
139 | int try_to_free_buffers(struct page *); | |
140 | struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, | |
141 | int retry); | |
142 | void create_empty_buffers(struct page *, unsigned long, | |
143 | unsigned long b_state); | |
144 | void end_buffer_read_sync(struct buffer_head *bh, int uptodate); | |
145 | void end_buffer_write_sync(struct buffer_head *bh, int uptodate); | |
146 | void end_buffer_async_write(struct buffer_head *bh, int uptodate); | |
147 | ||
148 | /* Things to do with buffers at mapping->private_list */ | |
149 | void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode); | |
150 | int inode_has_buffers(struct inode *); | |
151 | void invalidate_inode_buffers(struct inode *); | |
152 | int remove_inode_buffers(struct inode *inode); | |
153 | int sync_mapping_buffers(struct address_space *mapping); | |
154 | void unmap_underlying_metadata(struct block_device *bdev, sector_t block); | |
155 | ||
156 | void mark_buffer_async_write(struct buffer_head *bh); | |
157 | void invalidate_bdev(struct block_device *, int); | |
158 | int sync_blockdev(struct block_device *bdev); | |
159 | void __wait_on_buffer(struct buffer_head *); | |
160 | wait_queue_head_t *bh_waitq_head(struct buffer_head *bh); | |
161 | int fsync_bdev(struct block_device *); | |
162 | struct super_block *freeze_bdev(struct block_device *); | |
163 | void thaw_bdev(struct block_device *, struct super_block *); | |
164 | int fsync_super(struct super_block *); | |
165 | int fsync_no_super(struct block_device *); | |
166 | struct buffer_head *__find_get_block(struct block_device *, sector_t, int); | |
167 | struct buffer_head * __getblk(struct block_device *, sector_t, int); | |
168 | void __brelse(struct buffer_head *); | |
169 | void __bforget(struct buffer_head *); | |
170 | void __breadahead(struct block_device *, sector_t block, int size); | |
171 | struct buffer_head *__bread(struct block_device *, sector_t block, int size); | |
172 | struct buffer_head *alloc_buffer_head(unsigned int __nocast gfp_flags); | |
173 | void free_buffer_head(struct buffer_head * bh); | |
174 | void FASTCALL(unlock_buffer(struct buffer_head *bh)); | |
175 | void FASTCALL(__lock_buffer(struct buffer_head *bh)); | |
176 | void ll_rw_block(int, int, struct buffer_head * bh[]); | |
177 | int sync_dirty_buffer(struct buffer_head *bh); | |
178 | int submit_bh(int, struct buffer_head *); | |
179 | void write_boundary_block(struct block_device *bdev, | |
180 | sector_t bblock, unsigned blocksize); | |
181 | ||
182 | extern int buffer_heads_over_limit; | |
183 | ||
184 | /* | |
185 | * Generic address_space_operations implementations for buffer_head-backed | |
186 | * address_spaces. | |
187 | */ | |
188 | int try_to_release_page(struct page * page, int gfp_mask); | |
189 | int block_invalidatepage(struct page *page, unsigned long offset); | |
190 | int block_write_full_page(struct page *page, get_block_t *get_block, | |
191 | struct writeback_control *wbc); | |
192 | int block_read_full_page(struct page*, get_block_t*); | |
193 | int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*); | |
194 | int cont_prepare_write(struct page*, unsigned, unsigned, get_block_t*, | |
195 | loff_t *); | |
196 | int generic_cont_expand(struct inode *inode, loff_t size) ; | |
197 | int block_commit_write(struct page *page, unsigned from, unsigned to); | |
198 | int block_sync_page(struct page *); | |
199 | sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *); | |
200 | int generic_commit_write(struct file *, struct page *, unsigned, unsigned); | |
201 | int block_truncate_page(struct address_space *, loff_t, get_block_t *); | |
202 | int file_fsync(struct file *, struct dentry *, int); | |
203 | int nobh_prepare_write(struct page*, unsigned, unsigned, get_block_t*); | |
204 | int nobh_commit_write(struct file *, struct page *, unsigned, unsigned); | |
205 | int nobh_truncate_page(struct address_space *, loff_t); | |
206 | int nobh_writepage(struct page *page, get_block_t *get_block, | |
207 | struct writeback_control *wbc); | |
208 | ||
209 | ||
210 | /* | |
211 | * inline definitions | |
212 | */ | |
213 | ||
214 | static inline void attach_page_buffers(struct page *page, | |
215 | struct buffer_head *head) | |
216 | { | |
217 | page_cache_get(page); | |
218 | SetPagePrivate(page); | |
219 | page->private = (unsigned long)head; | |
220 | } | |
221 | ||
222 | static inline void get_bh(struct buffer_head *bh) | |
223 | { | |
224 | atomic_inc(&bh->b_count); | |
225 | } | |
226 | ||
227 | static inline void put_bh(struct buffer_head *bh) | |
228 | { | |
229 | smp_mb__before_atomic_dec(); | |
230 | atomic_dec(&bh->b_count); | |
231 | } | |
232 | ||
233 | static inline void brelse(struct buffer_head *bh) | |
234 | { | |
235 | if (bh) | |
236 | __brelse(bh); | |
237 | } | |
238 | ||
239 | static inline void bforget(struct buffer_head *bh) | |
240 | { | |
241 | if (bh) | |
242 | __bforget(bh); | |
243 | } | |
244 | ||
245 | static inline struct buffer_head * | |
246 | sb_bread(struct super_block *sb, sector_t block) | |
247 | { | |
248 | return __bread(sb->s_bdev, block, sb->s_blocksize); | |
249 | } | |
250 | ||
251 | static inline void | |
252 | sb_breadahead(struct super_block *sb, sector_t block) | |
253 | { | |
254 | __breadahead(sb->s_bdev, block, sb->s_blocksize); | |
255 | } | |
256 | ||
257 | static inline struct buffer_head * | |
258 | sb_getblk(struct super_block *sb, sector_t block) | |
259 | { | |
260 | return __getblk(sb->s_bdev, block, sb->s_blocksize); | |
261 | } | |
262 | ||
263 | static inline struct buffer_head * | |
264 | sb_find_get_block(struct super_block *sb, sector_t block) | |
265 | { | |
266 | return __find_get_block(sb->s_bdev, block, sb->s_blocksize); | |
267 | } | |
268 | ||
269 | static inline void | |
270 | map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block) | |
271 | { | |
272 | set_buffer_mapped(bh); | |
273 | bh->b_bdev = sb->s_bdev; | |
274 | bh->b_blocknr = block; | |
275 | } | |
276 | ||
277 | /* | |
278 | * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into | |
279 | * __wait_on_buffer() just to trip a debug check. Because debug code in inline | |
280 | * functions is bloaty. | |
281 | */ | |
282 | static inline void wait_on_buffer(struct buffer_head *bh) | |
283 | { | |
284 | might_sleep(); | |
285 | if (buffer_locked(bh) || atomic_read(&bh->b_count) == 0) | |
286 | __wait_on_buffer(bh); | |
287 | } | |
288 | ||
289 | static inline void lock_buffer(struct buffer_head *bh) | |
290 | { | |
291 | might_sleep(); | |
292 | if (test_set_buffer_locked(bh)) | |
293 | __lock_buffer(bh); | |
294 | } | |
295 | ||
296 | #endif /* _LINUX_BUFFER_HEAD_H */ |