Line data Source code
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 <linux/atomic.h>
16 :
17 : #ifdef CONFIG_BLOCK
18 :
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 */
24 : BH_Uptodate_Lock,/* Used by the first bh in a page, to serialise
25 : * IO completion of other buffers in the page
26 : */
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_Unwritten, /* Buffer is allocated on disk but not written */
36 : BH_Quiet, /* Buffer Error Prinks to be quiet */
37 : BH_Meta, /* Buffer contains metadata */
38 : BH_Prio, /* Buffer should be submitted with REQ_PRIO */
39 : BH_Defer_Completion, /* Defer AIO completion to workqueue */
40 :
41 : BH_PrivateStart,/* not a state bit, but the first bit available
42 : * for private allocation by other entities
43 : */
44 : };
45 :
46 : #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512)
47 :
48 : struct page;
49 : struct buffer_head;
50 : struct address_space;
51 : typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
52 :
53 : /*
54 : * Historically, a buffer_head was used to map a single block
55 : * within a page, and of course as the unit of I/O through the
56 : * filesystem and block layers. Nowadays the basic I/O unit
57 : * is the bio, and buffer_heads are used for extracting block
58 : * mappings (via a get_block_t call), for tracking state within
59 : * a page (via a page_mapping) and for wrapping bio submission
60 : * for backward compatibility reasons (e.g. submit_bh).
61 : */
62 : struct buffer_head {
63 : unsigned long b_state; /* buffer state bitmap (see above) */
64 : struct buffer_head *b_this_page;/* circular list of page's buffers */
65 : struct page *b_page; /* the page this bh is mapped to */
66 :
67 : sector_t b_blocknr; /* start block number */
68 : size_t b_size; /* size of mapping */
69 : char *b_data; /* pointer to data within the page */
70 :
71 : struct block_device *b_bdev;
72 : bh_end_io_t *b_end_io; /* I/O completion */
73 : void *b_private; /* reserved for b_end_io */
74 : struct list_head b_assoc_buffers; /* associated with another mapping */
75 : struct address_space *b_assoc_map; /* mapping this buffer is
76 : associated with */
77 : atomic_t b_count; /* users using this buffer_head */
78 : };
79 :
80 : /*
81 : * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
82 : * and buffer_foo() functions.
83 : */
84 : #define BUFFER_FNS(bit, name) \
85 : static inline void set_buffer_##name(struct buffer_head *bh) \
86 : { \
87 : set_bit(BH_##bit, &(bh)->b_state); \
88 : } \
89 : static inline void clear_buffer_##name(struct buffer_head *bh) \
90 : { \
91 : clear_bit(BH_##bit, &(bh)->b_state); \
92 : } \
93 : static inline int buffer_##name(const struct buffer_head *bh) \
94 : { \
95 : return test_bit(BH_##bit, &(bh)->b_state); \
96 : }
97 :
98 : /*
99 : * test_set_buffer_foo() and test_clear_buffer_foo()
100 : */
101 : #define TAS_BUFFER_FNS(bit, name) \
102 : static inline int test_set_buffer_##name(struct buffer_head *bh) \
103 : { \
104 : return test_and_set_bit(BH_##bit, &(bh)->b_state); \
105 : } \
106 : static inline int test_clear_buffer_##name(struct buffer_head *bh) \
107 : { \
108 : return test_and_clear_bit(BH_##bit, &(bh)->b_state); \
109 : } \
110 :
111 : /*
112 : * Emit the buffer bitops functions. Note that there are also functions
113 : * of the form "mark_buffer_foo()". These are higher-level functions which
114 : * do something in addition to setting a b_state bit.
115 : */
116 : BUFFER_FNS(Uptodate, uptodate)
117 : BUFFER_FNS(Dirty, dirty)
118 : TAS_BUFFER_FNS(Dirty, dirty)
119 : BUFFER_FNS(Lock, locked)
120 : BUFFER_FNS(Req, req)
121 : TAS_BUFFER_FNS(Req, req)
122 : BUFFER_FNS(Mapped, mapped)
123 : BUFFER_FNS(New, new)
124 : BUFFER_FNS(Async_Read, async_read)
125 : BUFFER_FNS(Async_Write, async_write)
126 : BUFFER_FNS(Delay, delay)
127 : BUFFER_FNS(Boundary, boundary)
128 : BUFFER_FNS(Write_EIO, write_io_error)
129 : BUFFER_FNS(Unwritten, unwritten)
130 : BUFFER_FNS(Meta, meta)
131 : BUFFER_FNS(Prio, prio)
132 : BUFFER_FNS(Defer_Completion, defer_completion)
133 :
134 : #define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK)
135 :
136 : /* If we *know* page->private refers to buffer_heads */
137 : #define page_buffers(page) \
138 : ({ \
139 : BUG_ON(!PagePrivate(page)); \
140 : ((struct buffer_head *)page_private(page)); \
141 : })
142 : #define page_has_buffers(page) PagePrivate(page)
143 :
144 : void buffer_check_dirty_writeback(struct page *page,
145 : bool *dirty, bool *writeback);
146 :
147 : /*
148 : * Declarations
149 : */
150 :
151 : void mark_buffer_dirty(struct buffer_head *bh);
152 : void init_buffer(struct buffer_head *, bh_end_io_t *, void *);
153 : void touch_buffer(struct buffer_head *bh);
154 : void set_bh_page(struct buffer_head *bh,
155 : struct page *page, unsigned long offset);
156 : int try_to_free_buffers(struct page *);
157 : struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
158 : int retry);
159 : void create_empty_buffers(struct page *, unsigned long,
160 : unsigned long b_state);
161 : void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
162 : void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
163 : void end_buffer_async_write(struct buffer_head *bh, int uptodate);
164 :
165 : /* Things to do with buffers at mapping->private_list */
166 : void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
167 : int inode_has_buffers(struct inode *);
168 : void invalidate_inode_buffers(struct inode *);
169 : int remove_inode_buffers(struct inode *inode);
170 : int sync_mapping_buffers(struct address_space *mapping);
171 : void unmap_underlying_metadata(struct block_device *bdev, sector_t block);
172 :
173 : void mark_buffer_async_write(struct buffer_head *bh);
174 : void __wait_on_buffer(struct buffer_head *);
175 : wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
176 : struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block,
177 : unsigned size);
178 : struct buffer_head *__getblk(struct block_device *bdev, sector_t block,
179 : unsigned size);
180 : void __brelse(struct buffer_head *);
181 : void __bforget(struct buffer_head *);
182 : void __breadahead(struct block_device *, sector_t block, unsigned int size);
183 : struct buffer_head *__bread(struct block_device *, sector_t block, unsigned size);
184 : void invalidate_bh_lrus(void);
185 : struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
186 : void free_buffer_head(struct buffer_head * bh);
187 : void unlock_buffer(struct buffer_head *bh);
188 : void __lock_buffer(struct buffer_head *bh);
189 : void ll_rw_block(int, int, struct buffer_head * bh[]);
190 : int sync_dirty_buffer(struct buffer_head *bh);
191 : int __sync_dirty_buffer(struct buffer_head *bh, int rw);
192 : void write_dirty_buffer(struct buffer_head *bh, int rw);
193 : int _submit_bh(int rw, struct buffer_head *bh, unsigned long bio_flags);
194 : int submit_bh(int, struct buffer_head *);
195 : void write_boundary_block(struct block_device *bdev,
196 : sector_t bblock, unsigned blocksize);
197 : int bh_uptodate_or_lock(struct buffer_head *bh);
198 : int bh_submit_read(struct buffer_head *bh);
199 :
200 : extern int buffer_heads_over_limit;
201 :
202 : /*
203 : * Generic address_space_operations implementations for buffer_head-backed
204 : * address_spaces.
205 : */
206 : void block_invalidatepage(struct page *page, unsigned int offset,
207 : unsigned int length);
208 : int block_write_full_page(struct page *page, get_block_t *get_block,
209 : struct writeback_control *wbc);
210 : int block_read_full_page(struct page*, get_block_t*);
211 : int block_is_partially_uptodate(struct page *page, unsigned long from,
212 : unsigned long count);
213 : int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
214 : unsigned flags, struct page **pagep, get_block_t *get_block);
215 : int __block_write_begin(struct page *page, loff_t pos, unsigned len,
216 : get_block_t *get_block);
217 : int block_write_end(struct file *, struct address_space *,
218 : loff_t, unsigned, unsigned,
219 : struct page *, void *);
220 : int generic_write_end(struct file *, struct address_space *,
221 : loff_t, unsigned, unsigned,
222 : struct page *, void *);
223 : void page_zero_new_buffers(struct page *page, unsigned from, unsigned to);
224 : int cont_write_begin(struct file *, struct address_space *, loff_t,
225 : unsigned, unsigned, struct page **, void **,
226 : get_block_t *, loff_t *);
227 : int generic_cont_expand_simple(struct inode *inode, loff_t size);
228 : int block_commit_write(struct page *page, unsigned from, unsigned to);
229 : int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
230 : get_block_t get_block);
231 : int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
232 : get_block_t get_block);
233 : /* Convert errno to return value from ->page_mkwrite() call */
234 : static inline int block_page_mkwrite_return(int err)
235 : {
236 : if (err == 0)
237 : return VM_FAULT_LOCKED;
238 : if (err == -EFAULT)
239 : return VM_FAULT_NOPAGE;
240 : if (err == -ENOMEM)
241 : return VM_FAULT_OOM;
242 : if (err == -EAGAIN)
243 : return VM_FAULT_RETRY;
244 : /* -ENOSPC, -EDQUOT, -EIO ... */
245 : return VM_FAULT_SIGBUS;
246 : }
247 : sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
248 : int block_truncate_page(struct address_space *, loff_t, get_block_t *);
249 : int nobh_write_begin(struct address_space *, loff_t, unsigned, unsigned,
250 : struct page **, void **, get_block_t*);
251 : int nobh_write_end(struct file *, struct address_space *,
252 : loff_t, unsigned, unsigned,
253 : struct page *, void *);
254 : int nobh_truncate_page(struct address_space *, loff_t, get_block_t *);
255 : int nobh_writepage(struct page *page, get_block_t *get_block,
256 : struct writeback_control *wbc);
257 :
258 : void buffer_init(void);
259 :
260 : /*
261 : * inline definitions
262 : */
263 :
264 : static inline void attach_page_buffers(struct page *page,
265 : struct buffer_head *head)
266 : {
267 : page_cache_get(page);
268 : SetPagePrivate(page);
269 : set_page_private(page, (unsigned long)head);
270 : }
271 :
272 : static inline void get_bh(struct buffer_head *bh)
273 : {
274 5835 : atomic_inc(&bh->b_count);
275 : }
276 :
277 : static inline void put_bh(struct buffer_head *bh)
278 : {
279 5835 : smp_mb__before_atomic();
280 5835 : atomic_dec(&bh->b_count);
281 : }
282 :
283 : static inline void brelse(struct buffer_head *bh)
284 : {
285 12640 : if (bh)
286 12155 : __brelse(bh);
287 : }
288 :
289 : static inline void bforget(struct buffer_head *bh)
290 : {
291 : if (bh)
292 : __bforget(bh);
293 : }
294 :
295 : static inline struct buffer_head *
296 : sb_bread(struct super_block *sb, sector_t block)
297 : {
298 : return __bread(sb->s_bdev, block, sb->s_blocksize);
299 : }
300 :
301 : static inline void
302 : sb_breadahead(struct super_block *sb, sector_t block)
303 : {
304 : __breadahead(sb->s_bdev, block, sb->s_blocksize);
305 : }
306 :
307 : static inline struct buffer_head *
308 : sb_getblk(struct super_block *sb, sector_t block)
309 : {
310 : return __getblk(sb->s_bdev, block, sb->s_blocksize);
311 : }
312 :
313 : static inline struct buffer_head *
314 : sb_find_get_block(struct super_block *sb, sector_t block)
315 : {
316 : return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
317 : }
318 :
319 : static inline void
320 : map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
321 : {
322 : set_buffer_mapped(bh);
323 : bh->b_bdev = sb->s_bdev;
324 : bh->b_blocknr = block;
325 : bh->b_size = sb->s_blocksize;
326 : }
327 :
328 5835 : static inline void wait_on_buffer(struct buffer_head *bh)
329 : {
330 5835 : might_sleep();
331 5835 : if (buffer_locked(bh))
332 3612 : __wait_on_buffer(bh);
333 5835 : }
334 :
335 : static inline int trylock_buffer(struct buffer_head *bh)
336 : {
337 11670 : return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));
338 : }
339 :
340 5835 : static inline void lock_buffer(struct buffer_head *bh)
341 : {
342 5835 : might_sleep();
343 5835 : if (!trylock_buffer(bh))
344 0 : __lock_buffer(bh);
345 5835 : }
346 :
347 : extern int __set_page_dirty_buffers(struct page *page);
348 :
349 : #else /* CONFIG_BLOCK */
350 :
351 : static inline void buffer_init(void) {}
352 : static inline int try_to_free_buffers(struct page *page) { return 1; }
353 : static inline int inode_has_buffers(struct inode *inode) { return 0; }
354 : static inline void invalidate_inode_buffers(struct inode *inode) {}
355 : static inline int remove_inode_buffers(struct inode *inode) { return 1; }
356 : static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
357 :
358 : #endif /* CONFIG_BLOCK */
359 : #endif /* _LINUX_BUFFER_HEAD_H */
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