Commit | Line | Data |
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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 */ | |
a3972203 NP |
22 | BH_Uptodate_Lock,/* Used by the first bh in a page, to serialise |
23 | * IO completion of other buffers in the page | |
24 | */ | |
1da177e4 LT |
25 | |
26 | BH_Mapped, /* Has a disk mapping */ | |
27 | BH_New, /* Disk mapping was newly created by get_block */ | |
28 | BH_Async_Read, /* Is under end_buffer_async_read I/O */ | |
29 | BH_Async_Write, /* Is under end_buffer_async_write I/O */ | |
30 | BH_Delay, /* Buffer is not yet allocated on disk */ | |
31 | BH_Boundary, /* Block is followed by a discontiguity */ | |
32 | BH_Write_EIO, /* I/O error on write */ | |
33 | BH_Ordered, /* ordered write */ | |
34 | BH_Eopnotsupp, /* operation not supported (barrier) */ | |
35 | ||
36 | BH_PrivateStart,/* not a state bit, but the first bit available | |
37 | * for private allocation by other entities | |
38 | */ | |
39 | }; | |
40 | ||
41 | #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512) | |
42 | ||
43 | struct page; | |
44 | struct buffer_head; | |
45 | struct address_space; | |
46 | typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate); | |
47 | ||
48 | /* | |
205f87f6 BP |
49 | * Historically, a buffer_head was used to map a single block |
50 | * within a page, and of course as the unit of I/O through the | |
51 | * filesystem and block layers. Nowadays the basic I/O unit | |
52 | * is the bio, and buffer_heads are used for extracting block | |
53 | * mappings (via a get_block_t call), for tracking state within | |
54 | * a page (via a page_mapping) and for wrapping bio submission | |
55 | * for backward compatibility reasons (e.g. submit_bh). | |
1da177e4 LT |
56 | */ |
57 | struct buffer_head { | |
1da177e4 LT |
58 | unsigned long b_state; /* buffer state bitmap (see above) */ |
59 | struct buffer_head *b_this_page;/* circular list of page's buffers */ | |
60 | struct page *b_page; /* the page this bh is mapped to */ | |
1da177e4 | 61 | |
205f87f6 BP |
62 | sector_t b_blocknr; /* start block number */ |
63 | size_t b_size; /* size of mapping */ | |
64 | char *b_data; /* pointer to data within the page */ | |
1da177e4 LT |
65 | |
66 | struct block_device *b_bdev; | |
67 | bh_end_io_t *b_end_io; /* I/O completion */ | |
68 | void *b_private; /* reserved for b_end_io */ | |
69 | struct list_head b_assoc_buffers; /* associated with another mapping */ | |
205f87f6 | 70 | atomic_t b_count; /* users using this buffer_head */ |
1da177e4 LT |
71 | }; |
72 | ||
73 | /* | |
74 | * macro tricks to expand the set_buffer_foo(), clear_buffer_foo() | |
75 | * and buffer_foo() functions. | |
76 | */ | |
77 | #define BUFFER_FNS(bit, name) \ | |
78 | static inline void set_buffer_##name(struct buffer_head *bh) \ | |
79 | { \ | |
80 | set_bit(BH_##bit, &(bh)->b_state); \ | |
81 | } \ | |
82 | static inline void clear_buffer_##name(struct buffer_head *bh) \ | |
83 | { \ | |
84 | clear_bit(BH_##bit, &(bh)->b_state); \ | |
85 | } \ | |
86 | static inline int buffer_##name(const struct buffer_head *bh) \ | |
87 | { \ | |
88 | return test_bit(BH_##bit, &(bh)->b_state); \ | |
89 | } | |
90 | ||
91 | /* | |
92 | * test_set_buffer_foo() and test_clear_buffer_foo() | |
93 | */ | |
94 | #define TAS_BUFFER_FNS(bit, name) \ | |
95 | static inline int test_set_buffer_##name(struct buffer_head *bh) \ | |
96 | { \ | |
97 | return test_and_set_bit(BH_##bit, &(bh)->b_state); \ | |
98 | } \ | |
99 | static inline int test_clear_buffer_##name(struct buffer_head *bh) \ | |
100 | { \ | |
101 | return test_and_clear_bit(BH_##bit, &(bh)->b_state); \ | |
102 | } \ | |
103 | ||
104 | /* | |
105 | * Emit the buffer bitops functions. Note that there are also functions | |
106 | * of the form "mark_buffer_foo()". These are higher-level functions which | |
107 | * do something in addition to setting a b_state bit. | |
108 | */ | |
109 | BUFFER_FNS(Uptodate, uptodate) | |
110 | BUFFER_FNS(Dirty, dirty) | |
111 | TAS_BUFFER_FNS(Dirty, dirty) | |
112 | BUFFER_FNS(Lock, locked) | |
113 | TAS_BUFFER_FNS(Lock, locked) | |
114 | BUFFER_FNS(Req, req) | |
115 | TAS_BUFFER_FNS(Req, req) | |
116 | BUFFER_FNS(Mapped, mapped) | |
117 | BUFFER_FNS(New, new) | |
118 | BUFFER_FNS(Async_Read, async_read) | |
119 | BUFFER_FNS(Async_Write, async_write) | |
120 | BUFFER_FNS(Delay, delay) | |
121 | BUFFER_FNS(Boundary, boundary) | |
122 | BUFFER_FNS(Write_EIO, write_io_error) | |
123 | BUFFER_FNS(Ordered, ordered) | |
124 | BUFFER_FNS(Eopnotsupp, eopnotsupp) | |
125 | ||
126 | #define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK) | |
127 | #define touch_buffer(bh) mark_page_accessed(bh->b_page) | |
128 | ||
129 | /* If we *know* page->private refers to buffer_heads */ | |
130 | #define page_buffers(page) \ | |
131 | ({ \ | |
4c21e2f2 HD |
132 | BUG_ON(!PagePrivate(page)); \ |
133 | ((struct buffer_head *)page_private(page)); \ | |
1da177e4 LT |
134 | }) |
135 | #define page_has_buffers(page) PagePrivate(page) | |
136 | ||
137 | /* | |
138 | * Declarations | |
139 | */ | |
140 | ||
141 | void FASTCALL(mark_buffer_dirty(struct buffer_head *bh)); | |
142 | void init_buffer(struct buffer_head *, bh_end_io_t *, void *); | |
143 | void set_bh_page(struct buffer_head *bh, | |
144 | struct page *page, unsigned long offset); | |
145 | int try_to_free_buffers(struct page *); | |
146 | struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, | |
147 | int retry); | |
148 | void create_empty_buffers(struct page *, unsigned long, | |
149 | unsigned long b_state); | |
150 | void end_buffer_read_sync(struct buffer_head *bh, int uptodate); | |
151 | void end_buffer_write_sync(struct buffer_head *bh, int uptodate); | |
1da177e4 LT |
152 | |
153 | /* Things to do with buffers at mapping->private_list */ | |
154 | void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode); | |
155 | int inode_has_buffers(struct inode *); | |
156 | void invalidate_inode_buffers(struct inode *); | |
157 | int remove_inode_buffers(struct inode *inode); | |
158 | int sync_mapping_buffers(struct address_space *mapping); | |
159 | void unmap_underlying_metadata(struct block_device *bdev, sector_t block); | |
160 | ||
161 | void mark_buffer_async_write(struct buffer_head *bh); | |
162 | void invalidate_bdev(struct block_device *, int); | |
163 | int sync_blockdev(struct block_device *bdev); | |
164 | void __wait_on_buffer(struct buffer_head *); | |
165 | wait_queue_head_t *bh_waitq_head(struct buffer_head *bh); | |
166 | int fsync_bdev(struct block_device *); | |
167 | struct super_block *freeze_bdev(struct block_device *); | |
168 | void thaw_bdev(struct block_device *, struct super_block *); | |
169 | int fsync_super(struct super_block *); | |
170 | int fsync_no_super(struct block_device *); | |
171 | struct buffer_head *__find_get_block(struct block_device *, sector_t, int); | |
172 | struct buffer_head * __getblk(struct block_device *, sector_t, int); | |
173 | void __brelse(struct buffer_head *); | |
174 | void __bforget(struct buffer_head *); | |
175 | void __breadahead(struct block_device *, sector_t block, int size); | |
176 | struct buffer_head *__bread(struct block_device *, sector_t block, int size); | |
dd0fc66f | 177 | struct buffer_head *alloc_buffer_head(gfp_t gfp_flags); |
1da177e4 LT |
178 | void free_buffer_head(struct buffer_head * bh); |
179 | void FASTCALL(unlock_buffer(struct buffer_head *bh)); | |
180 | void FASTCALL(__lock_buffer(struct buffer_head *bh)); | |
181 | void ll_rw_block(int, int, struct buffer_head * bh[]); | |
182 | int sync_dirty_buffer(struct buffer_head *bh); | |
183 | int submit_bh(int, struct buffer_head *); | |
184 | void write_boundary_block(struct block_device *bdev, | |
185 | sector_t bblock, unsigned blocksize); | |
186 | ||
187 | extern int buffer_heads_over_limit; | |
188 | ||
189 | /* | |
190 | * Generic address_space_operations implementations for buffer_head-backed | |
191 | * address_spaces. | |
192 | */ | |
27496a8c | 193 | int try_to_release_page(struct page * page, gfp_t gfp_mask); |
2ff28e22 N |
194 | void block_invalidatepage(struct page *page, unsigned long offset); |
195 | void do_invalidatepage(struct page *page, unsigned long offset); | |
1da177e4 LT |
196 | int block_write_full_page(struct page *page, get_block_t *get_block, |
197 | struct writeback_control *wbc); | |
198 | int block_read_full_page(struct page*, get_block_t*); | |
199 | int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*); | |
200 | int cont_prepare_write(struct page*, unsigned, unsigned, get_block_t*, | |
201 | loff_t *); | |
05eb0b51 OH |
202 | int generic_cont_expand(struct inode *inode, loff_t size); |
203 | int generic_cont_expand_simple(struct inode *inode, loff_t size); | |
1da177e4 | 204 | int block_commit_write(struct page *page, unsigned from, unsigned to); |
3978d717 | 205 | void block_sync_page(struct page *); |
1da177e4 LT |
206 | sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *); |
207 | int generic_commit_write(struct file *, struct page *, unsigned, unsigned); | |
208 | int block_truncate_page(struct address_space *, loff_t, get_block_t *); | |
209 | int file_fsync(struct file *, struct dentry *, int); | |
210 | int nobh_prepare_write(struct page*, unsigned, unsigned, get_block_t*); | |
211 | int nobh_commit_write(struct file *, struct page *, unsigned, unsigned); | |
212 | int nobh_truncate_page(struct address_space *, loff_t); | |
213 | int nobh_writepage(struct page *page, get_block_t *get_block, | |
214 | struct writeback_control *wbc); | |
215 | ||
b6cd0b77 | 216 | void buffer_init(void); |
1da177e4 LT |
217 | |
218 | /* | |
219 | * inline definitions | |
220 | */ | |
221 | ||
222 | static inline void attach_page_buffers(struct page *page, | |
223 | struct buffer_head *head) | |
224 | { | |
225 | page_cache_get(page); | |
226 | SetPagePrivate(page); | |
4c21e2f2 | 227 | set_page_private(page, (unsigned long)head); |
1da177e4 LT |
228 | } |
229 | ||
230 | static inline void get_bh(struct buffer_head *bh) | |
231 | { | |
232 | atomic_inc(&bh->b_count); | |
233 | } | |
234 | ||
235 | static inline void put_bh(struct buffer_head *bh) | |
236 | { | |
237 | smp_mb__before_atomic_dec(); | |
238 | atomic_dec(&bh->b_count); | |
239 | } | |
240 | ||
241 | static inline void brelse(struct buffer_head *bh) | |
242 | { | |
243 | if (bh) | |
244 | __brelse(bh); | |
245 | } | |
246 | ||
247 | static inline void bforget(struct buffer_head *bh) | |
248 | { | |
249 | if (bh) | |
250 | __bforget(bh); | |
251 | } | |
252 | ||
253 | static inline struct buffer_head * | |
254 | sb_bread(struct super_block *sb, sector_t block) | |
255 | { | |
256 | return __bread(sb->s_bdev, block, sb->s_blocksize); | |
257 | } | |
258 | ||
259 | static inline void | |
260 | sb_breadahead(struct super_block *sb, sector_t block) | |
261 | { | |
262 | __breadahead(sb->s_bdev, block, sb->s_blocksize); | |
263 | } | |
264 | ||
265 | static inline struct buffer_head * | |
266 | sb_getblk(struct super_block *sb, sector_t block) | |
267 | { | |
268 | return __getblk(sb->s_bdev, block, sb->s_blocksize); | |
269 | } | |
270 | ||
271 | static inline struct buffer_head * | |
272 | sb_find_get_block(struct super_block *sb, sector_t block) | |
273 | { | |
274 | return __find_get_block(sb->s_bdev, block, sb->s_blocksize); | |
275 | } | |
276 | ||
277 | static inline void | |
278 | map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block) | |
279 | { | |
280 | set_buffer_mapped(bh); | |
281 | bh->b_bdev = sb->s_bdev; | |
282 | bh->b_blocknr = block; | |
b0cf2321 | 283 | bh->b_size = sb->s_blocksize; |
1da177e4 LT |
284 | } |
285 | ||
286 | /* | |
287 | * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into | |
288 | * __wait_on_buffer() just to trip a debug check. Because debug code in inline | |
289 | * functions is bloaty. | |
290 | */ | |
291 | static inline void wait_on_buffer(struct buffer_head *bh) | |
292 | { | |
293 | might_sleep(); | |
294 | if (buffer_locked(bh) || atomic_read(&bh->b_count) == 0) | |
295 | __wait_on_buffer(bh); | |
296 | } | |
297 | ||
298 | static inline void lock_buffer(struct buffer_head *bh) | |
299 | { | |
300 | might_sleep(); | |
301 | if (test_set_buffer_locked(bh)) | |
302 | __lock_buffer(bh); | |
303 | } | |
304 | ||
305 | #endif /* _LINUX_BUFFER_HEAD_H */ |