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TOMOYO Linux Cross Reference
Linux/include/linux/buffer_head.h

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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 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_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         if (err == 0)
239                 return VM_FAULT_LOCKED;
240         if (err == -EFAULT)
241                 return VM_FAULT_NOPAGE;
242         if (err == -ENOMEM)
243                 return VM_FAULT_OOM;
244         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         set_page_private(page, (unsigned long)head);
272 }
273 
274 static inline void get_bh(struct buffer_head *bh)
275 {
276         atomic_inc(&bh->b_count);
277 }
278 
279 static inline void put_bh(struct buffer_head *bh)
280 {
281         smp_mb__before_atomic_dec();
282         atomic_dec(&bh->b_count);
283 }
284 
285 static inline void brelse(struct buffer_head *bh)
286 {
287         if (bh)
288                 __brelse(bh);
289 }
290 
291 static inline void bforget(struct buffer_head *bh)
292 {
293         if (bh)
294                 __bforget(bh);
295 }
296 
297 static inline struct buffer_head *
298 sb_bread(struct super_block *sb, sector_t block)
299 {
300         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         __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         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         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         bh->b_bdev = sb->s_bdev;
326         bh->b_blocknr = block;
327         bh->b_size = sb->s_blocksize;
328 }
329 
330 static inline void wait_on_buffer(struct buffer_head *bh)
331 {
332         might_sleep();
333         if (buffer_locked(bh))
334                 __wait_on_buffer(bh);
335 }
336 
337 static inline int trylock_buffer(struct buffer_head *bh)
338 {
339         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         if (!trylock_buffer(bh))
346                 __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 */
362 

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