Commit | Line | Data |
---|---|---|
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 | ||
9361401e DH |
17 | #ifdef CONFIG_BLOCK |
18 | ||
1da177e4 LT |
19 | enum bh_state_bits { |
20 | BH_Uptodate, /* Contains valid data */ | |
21 | BH_Dirty, /* Is dirty */ | |
22 | BH_Lock, /* Is locked */ | |
23 | BH_Req, /* Has been submitted for I/O */ | |
a3972203 NP |
24 | BH_Uptodate_Lock,/* Used by the first bh in a page, to serialise |
25 | * IO completion of other buffers in the page | |
26 | */ | |
1da177e4 LT |
27 | |
28 | BH_Mapped, /* Has a disk mapping */ | |
29 | BH_New, /* Disk mapping was newly created by get_block */ | |
30 | BH_Async_Read, /* Is under end_buffer_async_read I/O */ | |
31 | BH_Async_Write, /* Is under end_buffer_async_write I/O */ | |
32 | BH_Delay, /* Buffer is not yet allocated on disk */ | |
33 | BH_Boundary, /* Block is followed by a discontiguity */ | |
34 | BH_Write_EIO, /* I/O error on write */ | |
35 | BH_Ordered, /* ordered write */ | |
36 | BH_Eopnotsupp, /* operation not supported (barrier) */ | |
33a266dd | 37 | BH_Unwritten, /* Buffer is allocated on disk but not written */ |
08bafc03 | 38 | BH_Quiet, /* Buffer Error Prinks to be quiet */ |
1da177e4 LT |
39 | |
40 | BH_PrivateStart,/* not a state bit, but the first bit available | |
41 | * for private allocation by other entities | |
42 | */ | |
43 | }; | |
44 | ||
45 | #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512) | |
46 | ||
47 | struct page; | |
48 | struct buffer_head; | |
49 | struct address_space; | |
50 | typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate); | |
51 | ||
52 | /* | |
205f87f6 BP |
53 | * Historically, a buffer_head was used to map a single block |
54 | * within a page, and of course as the unit of I/O through the | |
55 | * filesystem and block layers. Nowadays the basic I/O unit | |
56 | * is the bio, and buffer_heads are used for extracting block | |
57 | * mappings (via a get_block_t call), for tracking state within | |
58 | * a page (via a page_mapping) and for wrapping bio submission | |
59 | * for backward compatibility reasons (e.g. submit_bh). | |
1da177e4 LT |
60 | */ |
61 | struct buffer_head { | |
1da177e4 LT |
62 | unsigned long b_state; /* buffer state bitmap (see above) */ |
63 | struct buffer_head *b_this_page;/* circular list of page's buffers */ | |
64 | struct page *b_page; /* the page this bh is mapped to */ | |
1da177e4 | 65 | |
205f87f6 BP |
66 | sector_t b_blocknr; /* start block number */ |
67 | size_t b_size; /* size of mapping */ | |
68 | char *b_data; /* pointer to data within the page */ | |
1da177e4 LT |
69 | |
70 | struct block_device *b_bdev; | |
71 | bh_end_io_t *b_end_io; /* I/O completion */ | |
72 | void *b_private; /* reserved for b_end_io */ | |
73 | struct list_head b_assoc_buffers; /* associated with another mapping */ | |
58ff407b JK |
74 | struct address_space *b_assoc_map; /* mapping this buffer is |
75 | associated with */ | |
205f87f6 | 76 | atomic_t b_count; /* users using this buffer_head */ |
1da177e4 LT |
77 | }; |
78 | ||
79 | /* | |
80 | * macro tricks to expand the set_buffer_foo(), clear_buffer_foo() | |
81 | * and buffer_foo() functions. | |
82 | */ | |
83 | #define BUFFER_FNS(bit, name) \ | |
84 | static inline void set_buffer_##name(struct buffer_head *bh) \ | |
85 | { \ | |
86 | set_bit(BH_##bit, &(bh)->b_state); \ | |
87 | } \ | |
88 | static inline void clear_buffer_##name(struct buffer_head *bh) \ | |
89 | { \ | |
90 | clear_bit(BH_##bit, &(bh)->b_state); \ | |
91 | } \ | |
92 | static inline int buffer_##name(const struct buffer_head *bh) \ | |
93 | { \ | |
94 | return test_bit(BH_##bit, &(bh)->b_state); \ | |
95 | } | |
96 | ||
97 | /* | |
98 | * test_set_buffer_foo() and test_clear_buffer_foo() | |
99 | */ | |
100 | #define TAS_BUFFER_FNS(bit, name) \ | |
101 | static inline int test_set_buffer_##name(struct buffer_head *bh) \ | |
102 | { \ | |
103 | return test_and_set_bit(BH_##bit, &(bh)->b_state); \ | |
104 | } \ | |
105 | static inline int test_clear_buffer_##name(struct buffer_head *bh) \ | |
106 | { \ | |
107 | return test_and_clear_bit(BH_##bit, &(bh)->b_state); \ | |
108 | } \ | |
109 | ||
110 | /* | |
111 | * Emit the buffer bitops functions. Note that there are also functions | |
112 | * of the form "mark_buffer_foo()". These are higher-level functions which | |
113 | * do something in addition to setting a b_state bit. | |
114 | */ | |
115 | BUFFER_FNS(Uptodate, uptodate) | |
116 | BUFFER_FNS(Dirty, dirty) | |
117 | TAS_BUFFER_FNS(Dirty, dirty) | |
118 | BUFFER_FNS(Lock, locked) | |
1da177e4 LT |
119 | BUFFER_FNS(Req, req) |
120 | TAS_BUFFER_FNS(Req, req) | |
121 | BUFFER_FNS(Mapped, mapped) | |
122 | BUFFER_FNS(New, new) | |
123 | BUFFER_FNS(Async_Read, async_read) | |
124 | BUFFER_FNS(Async_Write, async_write) | |
125 | BUFFER_FNS(Delay, delay) | |
126 | BUFFER_FNS(Boundary, boundary) | |
127 | BUFFER_FNS(Write_EIO, write_io_error) | |
128 | BUFFER_FNS(Ordered, ordered) | |
129 | BUFFER_FNS(Eopnotsupp, eopnotsupp) | |
33a266dd | 130 | BUFFER_FNS(Unwritten, unwritten) |
1da177e4 LT |
131 | |
132 | #define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK) | |
133 | #define touch_buffer(bh) mark_page_accessed(bh->b_page) | |
134 | ||
135 | /* If we *know* page->private refers to buffer_heads */ | |
136 | #define page_buffers(page) \ | |
137 | ({ \ | |
4c21e2f2 HD |
138 | BUG_ON(!PagePrivate(page)); \ |
139 | ((struct buffer_head *)page_private(page)); \ | |
1da177e4 LT |
140 | }) |
141 | #define page_has_buffers(page) PagePrivate(page) | |
142 | ||
143 | /* | |
144 | * Declarations | |
145 | */ | |
146 | ||
b3c97528 | 147 | void mark_buffer_dirty(struct buffer_head *bh); |
1da177e4 LT |
148 | void init_buffer(struct buffer_head *, bh_end_io_t *, void *); |
149 | void set_bh_page(struct buffer_head *bh, | |
150 | struct page *page, unsigned long offset); | |
151 | int try_to_free_buffers(struct page *); | |
152 | struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, | |
153 | int retry); | |
154 | void create_empty_buffers(struct page *, unsigned long, | |
155 | unsigned long b_state); | |
156 | void end_buffer_read_sync(struct buffer_head *bh, int uptodate); | |
157 | void end_buffer_write_sync(struct buffer_head *bh, int uptodate); | |
35c80d5f | 158 | void end_buffer_async_write(struct buffer_head *bh, int uptodate); |
1da177e4 LT |
159 | |
160 | /* Things to do with buffers at mapping->private_list */ | |
161 | void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode); | |
162 | int inode_has_buffers(struct inode *); | |
163 | void invalidate_inode_buffers(struct inode *); | |
164 | int remove_inode_buffers(struct inode *inode); | |
165 | int sync_mapping_buffers(struct address_space *mapping); | |
166 | void unmap_underlying_metadata(struct block_device *bdev, sector_t block); | |
167 | ||
168 | void mark_buffer_async_write(struct buffer_head *bh); | |
1da177e4 LT |
169 | void __wait_on_buffer(struct buffer_head *); |
170 | wait_queue_head_t *bh_waitq_head(struct buffer_head *bh); | |
3991d3bd TK |
171 | struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block, |
172 | unsigned size); | |
173 | struct buffer_head *__getblk(struct block_device *bdev, sector_t block, | |
174 | unsigned size); | |
1da177e4 LT |
175 | void __brelse(struct buffer_head *); |
176 | void __bforget(struct buffer_head *); | |
3991d3bd TK |
177 | void __breadahead(struct block_device *, sector_t block, unsigned int size); |
178 | struct buffer_head *__bread(struct block_device *, sector_t block, unsigned size); | |
f9a14399 | 179 | void invalidate_bh_lrus(void); |
dd0fc66f | 180 | struct buffer_head *alloc_buffer_head(gfp_t gfp_flags); |
1da177e4 | 181 | void free_buffer_head(struct buffer_head * bh); |
b3c97528 HH |
182 | void unlock_buffer(struct buffer_head *bh); |
183 | void __lock_buffer(struct buffer_head *bh); | |
1da177e4 LT |
184 | void ll_rw_block(int, int, struct buffer_head * bh[]); |
185 | int sync_dirty_buffer(struct buffer_head *bh); | |
186 | int submit_bh(int, struct buffer_head *); | |
187 | void write_boundary_block(struct block_device *bdev, | |
188 | sector_t bblock, unsigned blocksize); | |
389d1b08 AK |
189 | int bh_uptodate_or_lock(struct buffer_head *bh); |
190 | int bh_submit_read(struct buffer_head *bh); | |
1da177e4 LT |
191 | |
192 | extern int buffer_heads_over_limit; | |
193 | ||
194 | /* | |
195 | * Generic address_space_operations implementations for buffer_head-backed | |
196 | * address_spaces. | |
197 | */ | |
2ff28e22 | 198 | void block_invalidatepage(struct page *page, unsigned long offset); |
1da177e4 LT |
199 | int block_write_full_page(struct page *page, get_block_t *get_block, |
200 | struct writeback_control *wbc); | |
35c80d5f CM |
201 | int block_write_full_page_endio(struct page *page, get_block_t *get_block, |
202 | struct writeback_control *wbc, bh_end_io_t *handler); | |
1da177e4 | 203 | int block_read_full_page(struct page*, get_block_t*); |
8ab22b9a HH |
204 | int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc, |
205 | unsigned long from); | |
afddba49 NP |
206 | int block_write_begin(struct file *, struct address_space *, |
207 | loff_t, unsigned, unsigned, | |
208 | struct page **, void **, get_block_t*); | |
209 | int block_write_end(struct file *, struct address_space *, | |
210 | loff_t, unsigned, unsigned, | |
211 | struct page *, void *); | |
212 | int generic_write_end(struct file *, struct address_space *, | |
213 | loff_t, unsigned, unsigned, | |
214 | struct page *, void *); | |
215 | void page_zero_new_buffers(struct page *page, unsigned from, unsigned to); | |
1da177e4 | 216 | int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*); |
89e10787 NP |
217 | int cont_write_begin(struct file *, struct address_space *, loff_t, |
218 | unsigned, unsigned, struct page **, void **, | |
219 | get_block_t *, loff_t *); | |
05eb0b51 | 220 | int generic_cont_expand_simple(struct inode *inode, loff_t size); |
1da177e4 | 221 | int block_commit_write(struct page *page, unsigned from, unsigned to); |
c2ec175c | 222 | int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, |
54171690 | 223 | get_block_t get_block); |
3978d717 | 224 | void block_sync_page(struct page *); |
1da177e4 | 225 | sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *); |
1da177e4 LT |
226 | int block_truncate_page(struct address_space *, loff_t, get_block_t *); |
227 | int file_fsync(struct file *, struct dentry *, int); | |
03158cd7 NP |
228 | int nobh_write_begin(struct file *, struct address_space *, |
229 | loff_t, unsigned, unsigned, | |
230 | struct page **, void **, get_block_t*); | |
231 | int nobh_write_end(struct file *, struct address_space *, | |
232 | loff_t, unsigned, unsigned, | |
233 | struct page *, void *); | |
234 | int nobh_truncate_page(struct address_space *, loff_t, get_block_t *); | |
1da177e4 LT |
235 | int nobh_writepage(struct page *page, get_block_t *get_block, |
236 | struct writeback_control *wbc); | |
237 | ||
b6cd0b77 | 238 | void buffer_init(void); |
1da177e4 LT |
239 | |
240 | /* | |
241 | * inline definitions | |
242 | */ | |
243 | ||
244 | static inline void attach_page_buffers(struct page *page, | |
245 | struct buffer_head *head) | |
246 | { | |
247 | page_cache_get(page); | |
248 | SetPagePrivate(page); | |
4c21e2f2 | 249 | set_page_private(page, (unsigned long)head); |
1da177e4 LT |
250 | } |
251 | ||
252 | static inline void get_bh(struct buffer_head *bh) | |
253 | { | |
254 | atomic_inc(&bh->b_count); | |
255 | } | |
256 | ||
257 | static inline void put_bh(struct buffer_head *bh) | |
258 | { | |
259 | smp_mb__before_atomic_dec(); | |
260 | atomic_dec(&bh->b_count); | |
261 | } | |
262 | ||
263 | static inline void brelse(struct buffer_head *bh) | |
264 | { | |
265 | if (bh) | |
266 | __brelse(bh); | |
267 | } | |
268 | ||
269 | static inline void bforget(struct buffer_head *bh) | |
270 | { | |
271 | if (bh) | |
272 | __bforget(bh); | |
273 | } | |
274 | ||
275 | static inline struct buffer_head * | |
276 | sb_bread(struct super_block *sb, sector_t block) | |
277 | { | |
278 | return __bread(sb->s_bdev, block, sb->s_blocksize); | |
279 | } | |
280 | ||
281 | static inline void | |
282 | sb_breadahead(struct super_block *sb, sector_t block) | |
283 | { | |
284 | __breadahead(sb->s_bdev, block, sb->s_blocksize); | |
285 | } | |
286 | ||
287 | static inline struct buffer_head * | |
288 | sb_getblk(struct super_block *sb, sector_t block) | |
289 | { | |
290 | return __getblk(sb->s_bdev, block, sb->s_blocksize); | |
291 | } | |
292 | ||
293 | static inline struct buffer_head * | |
294 | sb_find_get_block(struct super_block *sb, sector_t block) | |
295 | { | |
296 | return __find_get_block(sb->s_bdev, block, sb->s_blocksize); | |
297 | } | |
298 | ||
299 | static inline void | |
300 | map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block) | |
301 | { | |
302 | set_buffer_mapped(bh); | |
303 | bh->b_bdev = sb->s_bdev; | |
304 | bh->b_blocknr = block; | |
b0cf2321 | 305 | bh->b_size = sb->s_blocksize; |
1da177e4 LT |
306 | } |
307 | ||
308 | /* | |
309 | * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into | |
310 | * __wait_on_buffer() just to trip a debug check. Because debug code in inline | |
311 | * functions is bloaty. | |
312 | */ | |
313 | static inline void wait_on_buffer(struct buffer_head *bh) | |
314 | { | |
315 | might_sleep(); | |
316 | if (buffer_locked(bh) || atomic_read(&bh->b_count) == 0) | |
317 | __wait_on_buffer(bh); | |
318 | } | |
319 | ||
ca5de404 NP |
320 | static inline int trylock_buffer(struct buffer_head *bh) |
321 | { | |
51b07fc3 | 322 | return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state)); |
ca5de404 NP |
323 | } |
324 | ||
1da177e4 LT |
325 | static inline void lock_buffer(struct buffer_head *bh) |
326 | { | |
327 | might_sleep(); | |
ca5de404 | 328 | if (!trylock_buffer(bh)) |
1da177e4 LT |
329 | __lock_buffer(bh); |
330 | } | |
331 | ||
cf9a2ae8 | 332 | extern int __set_page_dirty_buffers(struct page *page); |
9361401e DH |
333 | |
334 | #else /* CONFIG_BLOCK */ | |
335 | ||
336 | static inline void buffer_init(void) {} | |
337 | static inline int try_to_free_buffers(struct page *page) { return 1; } | |
9361401e DH |
338 | static inline int inode_has_buffers(struct inode *inode) { return 0; } |
339 | static inline void invalidate_inode_buffers(struct inode *inode) {} | |
340 | static inline int remove_inode_buffers(struct inode *inode) { return 1; } | |
341 | static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; } | |
9361401e DH |
342 | |
343 | #endif /* CONFIG_BLOCK */ | |
1da177e4 | 344 | #endif /* _LINUX_BUFFER_HEAD_H */ |