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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 : 7028571 : BUFFER_FNS(Uptodate, uptodate)
117 : 3547065 : BUFFER_FNS(Dirty, dirty)
118 : 2402460 : TAS_BUFFER_FNS(Dirty, dirty)
119 : : BUFFER_FNS(Lock, locked)
120 : 1720332 : BUFFER_FNS(Req, req)
121 : 118498 : TAS_BUFFER_FNS(Req, req)
122 : 4154515 : BUFFER_FNS(Mapped, mapped)
123 : 10090642 : BUFFER_FNS(New, new)
124 : 4720 : BUFFER_FNS(Async_Read, async_read)
125 : 1819240 : BUFFER_FNS(Async_Write, async_write)
126 : 5245302 : BUFFER_FNS(Delay, delay)
127 : 1 : BUFFER_FNS(Boundary, boundary)
128 : 25458 : BUFFER_FNS(Write_EIO, write_io_error)
129 : 2336003 : BUFFER_FNS(Unwritten, unwritten)
130 : 11096834 : BUFFER_FNS(Meta, meta)
131 : 11095102 : BUFFER_FNS(Prio, prio)
132 : 0 : 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_write_full_page_endio(struct page *page, get_block_t *get_block,
211 : : struct writeback_control *wbc, bh_end_io_t *handler);
212 : : int block_read_full_page(struct page*, get_block_t*);
213 : : int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc,
214 : : unsigned long from);
215 : : int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
216 : : unsigned flags, struct page **pagep, get_block_t *get_block);
217 : : int __block_write_begin(struct page *page, loff_t pos, unsigned len,
218 : : get_block_t *get_block);
219 : : int block_write_end(struct file *, struct address_space *,
220 : : loff_t, unsigned, unsigned,
221 : : struct page *, void *);
222 : : int generic_write_end(struct file *, struct address_space *,
223 : : loff_t, unsigned, unsigned,
224 : : struct page *, void *);
225 : : void page_zero_new_buffers(struct page *page, unsigned from, unsigned to);
226 : : int cont_write_begin(struct file *, struct address_space *, loff_t,
227 : : unsigned, unsigned, struct page **, void **,
228 : : get_block_t *, loff_t *);
229 : : int generic_cont_expand_simple(struct inode *inode, loff_t size);
230 : : int block_commit_write(struct page *page, unsigned from, unsigned to);
231 : : int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
232 : : get_block_t get_block);
233 : : int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
234 : : get_block_t get_block);
235 : : /* Convert errno to return value from ->page_mkwrite() call */
236 : : static inline int block_page_mkwrite_return(int err)
237 : : {
238 [ - + ][ # # ]: 205596 : if (err == 0)
239 : : return VM_FAULT_LOCKED;
240 [ # # ]: 0 : if (err == -EFAULT)
241 : : return VM_FAULT_NOPAGE;
242 [ # # ]: 0 : if (err == -ENOMEM)
243 : : return VM_FAULT_OOM;
244 [ # # ]: 205596 : if (err == -EAGAIN)
245 : : return VM_FAULT_RETRY;
246 : : /* -ENOSPC, -EDQUOT, -EIO ... */
247 : : return VM_FAULT_SIGBUS;
248 : : }
249 : : sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
250 : : int block_truncate_page(struct address_space *, loff_t, get_block_t *);
251 : : int nobh_write_begin(struct address_space *, loff_t, unsigned, unsigned,
252 : : struct page **, void **, get_block_t*);
253 : : int nobh_write_end(struct file *, struct address_space *,
254 : : loff_t, unsigned, unsigned,
255 : : struct page *, void *);
256 : : int nobh_truncate_page(struct address_space *, loff_t, get_block_t *);
257 : : int nobh_writepage(struct page *page, get_block_t *get_block,
258 : : struct writeback_control *wbc);
259 : :
260 : : void buffer_init(void);
261 : :
262 : : /*
263 : : * inline definitions
264 : : */
265 : :
266 : : static inline void attach_page_buffers(struct page *page,
267 : : struct buffer_head *head)
268 : : {
269 : : page_cache_get(page);
270 : : SetPagePrivate(page);
271 : 1827360 : set_page_private(page, (unsigned long)head);
272 : : }
273 : :
274 : : static inline void get_bh(struct buffer_head *bh)
275 : : {
276 : 221476 : atomic_inc(&bh->b_count);
277 : : }
278 : :
279 : : static inline void put_bh(struct buffer_head *bh)
280 : : {
281 : 19735472 : smp_mb__before_atomic_dec();
282 : 19732189 : atomic_dec(&bh->b_count);
283 : : }
284 : :
285 : : static inline void brelse(struct buffer_head *bh)
286 : : {
287 [ + + ][ + + ]: 11909708 : if (bh)
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288 : 10721357 : __brelse(bh);
289 : : }
290 : :
291 : : static inline void bforget(struct buffer_head *bh)
292 : : {
293 [ # # ][ # # ]: 0 : if (bh)
[ # # ][ # # ]
294 : 0 : __bforget(bh);
295 : : }
296 : :
297 : : static inline struct buffer_head *
298 : : sb_bread(struct super_block *sb, sector_t block)
299 : : {
300 : 120 : return __bread(sb->s_bdev, block, sb->s_blocksize);
301 : : }
302 : :
303 : : static inline void
304 : : sb_breadahead(struct super_block *sb, sector_t block)
305 : : {
306 : 6488 : __breadahead(sb->s_bdev, block, sb->s_blocksize);
307 : : }
308 : :
309 : : static inline struct buffer_head *
310 : : sb_getblk(struct super_block *sb, sector_t block)
311 : : {
312 : 10729064 : return __getblk(sb->s_bdev, block, sb->s_blocksize);
313 : : }
314 : :
315 : : static inline struct buffer_head *
316 : : sb_find_get_block(struct super_block *sb, sector_t block)
317 : : {
318 : 38290 : return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
319 : : }
320 : :
321 : : static inline void
322 : : map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
323 : : {
324 : : set_buffer_mapped(bh);
325 : 2285536 : bh->b_bdev = sb->s_bdev;
326 : 2285536 : bh->b_blocknr = block;
327 : 2285536 : bh->b_size = sb->s_blocksize;
328 : : }
329 : :
330 : : static inline void wait_on_buffer(struct buffer_head *bh)
331 : : {
332 : : might_sleep();
333 [ + + ][ + - : 711837 : if (buffer_locked(bh))
+ - + - ]
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334 : 39641 : __wait_on_buffer(bh);
335 : : }
336 : :
337 : : static inline int trylock_buffer(struct buffer_head *bh)
338 : : {
339 : 14401528 : return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));
340 : : }
341 : :
342 : : static inline void lock_buffer(struct buffer_head *bh)
343 : : {
344 : : might_sleep();
345 [ + + + + : 13755405 : if (!trylock_buffer(bh))
- + # # -
+ + + # #
- + - + ]
346 : 17597 : __lock_buffer(bh);
347 : : }
348 : :
349 : : extern int __set_page_dirty_buffers(struct page *page);
350 : :
351 : : #else /* CONFIG_BLOCK */
352 : :
353 : : static inline void buffer_init(void) {}
354 : : static inline int try_to_free_buffers(struct page *page) { return 1; }
355 : : static inline int inode_has_buffers(struct inode *inode) { return 0; }
356 : : static inline void invalidate_inode_buffers(struct inode *inode) {}
357 : : static inline int remove_inode_buffers(struct inode *inode) { return 1; }
358 : : static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
359 : :
360 : : #endif /* CONFIG_BLOCK */
361 : : #endif /* _LINUX_BUFFER_HEAD_H */
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