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

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  1 /* SPDX-License-Identifier: GPL-2.0 */
  2 /*
  3  * include/linux/buffer_head.h
  4  *
  5  * Everything to do with buffer_heads.
  6  */
  7 
  8 #ifndef _LINUX_BUFFER_HEAD_H
  9 #define _LINUX_BUFFER_HEAD_H
 10 
 11 #include <linux/types.h>
 12 #include <linux/fs.h>
 13 #include <linux/linkage.h>
 14 #include <linux/pagemap.h>
 15 #include <linux/wait.h>
 16 #include <linux/atomic.h>
 17 
 18 #ifdef CONFIG_BLOCK
 19 
 20 enum bh_state_bits {
 21         BH_Uptodate,    /* Contains valid data */
 22         BH_Dirty,       /* Is dirty */
 23         BH_Lock,        /* Is locked */
 24         BH_Req,         /* Has been submitted for I/O */
 25         BH_Uptodate_Lock,/* Used by the first bh in a page, to serialise
 26                           * IO completion of other buffers in the page
 27                           */
 28 
 29         BH_Mapped,      /* Has a disk mapping */
 30         BH_New,         /* Disk mapping was newly created by get_block */
 31         BH_Async_Read,  /* Is under end_buffer_async_read I/O */
 32         BH_Async_Write, /* Is under end_buffer_async_write I/O */
 33         BH_Delay,       /* Buffer is not yet allocated on disk */
 34         BH_Boundary,    /* Block is followed by a discontiguity */
 35         BH_Write_EIO,   /* I/O error on write */
 36         BH_Unwritten,   /* Buffer is allocated on disk but not written */
 37         BH_Quiet,       /* Buffer Error Prinks to be quiet */
 38         BH_Meta,        /* Buffer contains metadata */
 39         BH_Prio,        /* Buffer should be submitted with REQ_PRIO */
 40         BH_Defer_Completion, /* Defer AIO completion to workqueue */
 41 
 42         BH_PrivateStart,/* not a state bit, but the first bit available
 43                          * for private allocation by other entities
 44                          */
 45 };
 46 
 47 #define MAX_BUF_PER_PAGE (PAGE_SIZE / 512)
 48 
 49 struct page;
 50 struct buffer_head;
 51 struct address_space;
 52 typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
 53 
 54 /*
 55  * Historically, a buffer_head was used to map a single block
 56  * within a page, and of course as the unit of I/O through the
 57  * filesystem and block layers.  Nowadays the basic I/O unit
 58  * is the bio, and buffer_heads are used for extracting block
 59  * mappings (via a get_block_t call), for tracking state within
 60  * a page (via a page_mapping) and for wrapping bio submission
 61  * for backward compatibility reasons (e.g. submit_bh).
 62  */
 63 struct buffer_head {
 64         unsigned long b_state;          /* buffer state bitmap (see above) */
 65         struct buffer_head *b_this_page;/* circular list of page's buffers */
 66         struct page *b_page;            /* the page this bh is mapped to */
 67 
 68         sector_t b_blocknr;             /* start block number */
 69         size_t b_size;                  /* size of mapping */
 70         char *b_data;                   /* pointer to data within the page */
 71 
 72         struct block_device *b_bdev;
 73         bh_end_io_t *b_end_io;          /* I/O completion */
 74         void *b_private;                /* reserved for b_end_io */
 75         struct list_head b_assoc_buffers; /* associated with another mapping */
 76         struct address_space *b_assoc_map;      /* mapping this buffer is
 77                                                    associated with */
 78         atomic_t b_count;               /* users using this buffer_head */
 79 };
 80 
 81 /*
 82  * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
 83  * and buffer_foo() functions.
 84  */
 85 #define BUFFER_FNS(bit, name)                                           \
 86 static __always_inline void set_buffer_##name(struct buffer_head *bh)   \
 87 {                                                                       \
 88         set_bit(BH_##bit, &(bh)->b_state);                              \
 89 }                                                                       \
 90 static __always_inline void clear_buffer_##name(struct buffer_head *bh) \
 91 {                                                                       \
 92         clear_bit(BH_##bit, &(bh)->b_state);                            \
 93 }                                                                       \
 94 static __always_inline int buffer_##name(const struct buffer_head *bh)  \
 95 {                                                                       \
 96         return test_bit(BH_##bit, &(bh)->b_state);                      \
 97 }
 98 
 99 /*
100  * test_set_buffer_foo() and test_clear_buffer_foo()
101  */
102 #define TAS_BUFFER_FNS(bit, name)                                       \
103 static __always_inline int test_set_buffer_##name(struct buffer_head *bh) \
104 {                                                                       \
105         return test_and_set_bit(BH_##bit, &(bh)->b_state);              \
106 }                                                                       \
107 static __always_inline int test_clear_buffer_##name(struct buffer_head *bh) \
108 {                                                                       \
109         return test_and_clear_bit(BH_##bit, &(bh)->b_state);            \
110 }                                                                       \
111 
112 /*
113  * Emit the buffer bitops functions.   Note that there are also functions
114  * of the form "mark_buffer_foo()".  These are higher-level functions which
115  * do something in addition to setting a b_state bit.
116  */
117 BUFFER_FNS(Uptodate, uptodate)
118 BUFFER_FNS(Dirty, dirty)
119 TAS_BUFFER_FNS(Dirty, dirty)
120 BUFFER_FNS(Lock, locked)
121 BUFFER_FNS(Req, req)
122 TAS_BUFFER_FNS(Req, req)
123 BUFFER_FNS(Mapped, mapped)
124 BUFFER_FNS(New, new)
125 BUFFER_FNS(Async_Read, async_read)
126 BUFFER_FNS(Async_Write, async_write)
127 BUFFER_FNS(Delay, delay)
128 BUFFER_FNS(Boundary, boundary)
129 BUFFER_FNS(Write_EIO, write_io_error)
130 BUFFER_FNS(Unwritten, unwritten)
131 BUFFER_FNS(Meta, meta)
132 BUFFER_FNS(Prio, prio)
133 BUFFER_FNS(Defer_Completion, defer_completion)
134 
135 #define bh_offset(bh)           ((unsigned long)(bh)->b_data & ~PAGE_MASK)
136 
137 /* If we *know* page->private refers to buffer_heads */
138 #define page_buffers(page)                                      \
139         ({                                                      \
140                 BUG_ON(!PagePrivate(page));                     \
141                 ((struct buffer_head *)page_private(page));     \
142         })
143 #define page_has_buffers(page)  PagePrivate(page)
144 
145 void buffer_check_dirty_writeback(struct page *page,
146                                      bool *dirty, bool *writeback);
147 
148 /*
149  * Declarations
150  */
151 
152 void mark_buffer_dirty(struct buffer_head *bh);
153 void mark_buffer_write_io_error(struct buffer_head *bh);
154 void init_buffer(struct buffer_head *, bh_end_io_t *, void *);
155 void touch_buffer(struct buffer_head *bh);
156 void set_bh_page(struct buffer_head *bh,
157                 struct page *page, unsigned long offset);
158 int try_to_free_buffers(struct page *);
159 struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
160                 bool retry);
161 void create_empty_buffers(struct page *, unsigned long,
162                         unsigned long b_state);
163 void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
164 void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
165 void end_buffer_async_write(struct buffer_head *bh, int uptodate);
166 
167 /* Things to do with buffers at mapping->private_list */
168 void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
169 int inode_has_buffers(struct inode *);
170 void invalidate_inode_buffers(struct inode *);
171 int remove_inode_buffers(struct inode *inode);
172 int sync_mapping_buffers(struct address_space *mapping);
173 void clean_bdev_aliases(struct block_device *bdev, sector_t block,
174                         sector_t len);
175 static inline void clean_bdev_bh_alias(struct buffer_head *bh)
176 {
177         clean_bdev_aliases(bh->b_bdev, bh->b_blocknr, 1);
178 }
179 
180 void mark_buffer_async_write(struct buffer_head *bh);
181 void __wait_on_buffer(struct buffer_head *);
182 wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
183 struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block,
184                         unsigned size);
185 struct buffer_head *__getblk_gfp(struct block_device *bdev, sector_t block,
186                                   unsigned size, gfp_t gfp);
187 void __brelse(struct buffer_head *);
188 void __bforget(struct buffer_head *);
189 void __breadahead(struct block_device *, sector_t block, unsigned int size);
190 struct buffer_head *__bread_gfp(struct block_device *,
191                                 sector_t block, unsigned size, gfp_t gfp);
192 void invalidate_bh_lrus(void);
193 struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
194 void free_buffer_head(struct buffer_head * bh);
195 void unlock_buffer(struct buffer_head *bh);
196 void __lock_buffer(struct buffer_head *bh);
197 void ll_rw_block(int, int, int, struct buffer_head * bh[]);
198 int sync_dirty_buffer(struct buffer_head *bh);
199 int __sync_dirty_buffer(struct buffer_head *bh, int op_flags);
200 void write_dirty_buffer(struct buffer_head *bh, int op_flags);
201 int submit_bh(int, int, struct buffer_head *);
202 void write_boundary_block(struct block_device *bdev,
203                         sector_t bblock, unsigned blocksize);
204 int bh_uptodate_or_lock(struct buffer_head *bh);
205 int bh_submit_read(struct buffer_head *bh);
206 loff_t page_cache_seek_hole_data(struct inode *inode, loff_t offset,
207                                  loff_t length, int whence);
208 
209 extern int buffer_heads_over_limit;
210 
211 /*
212  * Generic address_space_operations implementations for buffer_head-backed
213  * address_spaces.
214  */
215 void block_invalidatepage(struct page *page, unsigned int offset,
216                           unsigned int length);
217 int block_write_full_page(struct page *page, get_block_t *get_block,
218                                 struct writeback_control *wbc);
219 int __block_write_full_page(struct inode *inode, struct page *page,
220                         get_block_t *get_block, struct writeback_control *wbc,
221                         bh_end_io_t *handler);
222 int block_read_full_page(struct page*, get_block_t*);
223 int block_is_partially_uptodate(struct page *page, unsigned long from,
224                                 unsigned long count);
225 int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
226                 unsigned flags, struct page **pagep, get_block_t *get_block);
227 int __block_write_begin(struct page *page, loff_t pos, unsigned len,
228                 get_block_t *get_block);
229 int block_write_end(struct file *, struct address_space *,
230                                 loff_t, unsigned, unsigned,
231                                 struct page *, void *);
232 int generic_write_end(struct file *, struct address_space *,
233                                 loff_t, unsigned, unsigned,
234                                 struct page *, void *);
235 void page_zero_new_buffers(struct page *page, unsigned from, unsigned to);
236 void clean_page_buffers(struct page *page);
237 int cont_write_begin(struct file *, struct address_space *, loff_t,
238                         unsigned, unsigned, struct page **, void **,
239                         get_block_t *, loff_t *);
240 int generic_cont_expand_simple(struct inode *inode, loff_t size);
241 int block_commit_write(struct page *page, unsigned from, unsigned to);
242 int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
243                                 get_block_t get_block);
244 /* Convert errno to return value from ->page_mkwrite() call */
245 static inline int block_page_mkwrite_return(int err)
246 {
247         if (err == 0)
248                 return VM_FAULT_LOCKED;
249         if (err == -EFAULT || err == -EAGAIN)
250                 return VM_FAULT_NOPAGE;
251         if (err == -ENOMEM)
252                 return VM_FAULT_OOM;
253         /* -ENOSPC, -EDQUOT, -EIO ... */
254         return VM_FAULT_SIGBUS;
255 }
256 sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
257 int block_truncate_page(struct address_space *, loff_t, get_block_t *);
258 int nobh_write_begin(struct address_space *, loff_t, unsigned, unsigned,
259                                 struct page **, void **, get_block_t*);
260 int nobh_write_end(struct file *, struct address_space *,
261                                 loff_t, unsigned, unsigned,
262                                 struct page *, void *);
263 int nobh_truncate_page(struct address_space *, loff_t, get_block_t *);
264 int nobh_writepage(struct page *page, get_block_t *get_block,
265                         struct writeback_control *wbc);
266 
267 void buffer_init(void);
268 
269 /*
270  * inline definitions
271  */
272 
273 static inline void attach_page_buffers(struct page *page,
274                 struct buffer_head *head)
275 {
276         get_page(page);
277         SetPagePrivate(page);
278         set_page_private(page, (unsigned long)head);
279 }
280 
281 static inline void get_bh(struct buffer_head *bh)
282 {
283         atomic_inc(&bh->b_count);
284 }
285 
286 static inline void put_bh(struct buffer_head *bh)
287 {
288         smp_mb__before_atomic();
289         atomic_dec(&bh->b_count);
290 }
291 
292 static inline void brelse(struct buffer_head *bh)
293 {
294         if (bh)
295                 __brelse(bh);
296 }
297 
298 static inline void bforget(struct buffer_head *bh)
299 {
300         if (bh)
301                 __bforget(bh);
302 }
303 
304 static inline struct buffer_head *
305 sb_bread(struct super_block *sb, sector_t block)
306 {
307         return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
308 }
309 
310 static inline struct buffer_head *
311 sb_bread_unmovable(struct super_block *sb, sector_t block)
312 {
313         return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, 0);
314 }
315 
316 static inline void
317 sb_breadahead(struct super_block *sb, sector_t block)
318 {
319         __breadahead(sb->s_bdev, block, sb->s_blocksize);
320 }
321 
322 static inline struct buffer_head *
323 sb_getblk(struct super_block *sb, sector_t block)
324 {
325         return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
326 }
327 
328 
329 static inline struct buffer_head *
330 sb_getblk_gfp(struct super_block *sb, sector_t block, gfp_t gfp)
331 {
332         return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, gfp);
333 }
334 
335 static inline struct buffer_head *
336 sb_find_get_block(struct super_block *sb, sector_t block)
337 {
338         return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
339 }
340 
341 static inline void
342 map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
343 {
344         set_buffer_mapped(bh);
345         bh->b_bdev = sb->s_bdev;
346         bh->b_blocknr = block;
347         bh->b_size = sb->s_blocksize;
348 }
349 
350 static inline void wait_on_buffer(struct buffer_head *bh)
351 {
352         might_sleep();
353         if (buffer_locked(bh))
354                 __wait_on_buffer(bh);
355 }
356 
357 static inline int trylock_buffer(struct buffer_head *bh)
358 {
359         return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));
360 }
361 
362 static inline void lock_buffer(struct buffer_head *bh)
363 {
364         might_sleep();
365         if (!trylock_buffer(bh))
366                 __lock_buffer(bh);
367 }
368 
369 static inline struct buffer_head *getblk_unmovable(struct block_device *bdev,
370                                                    sector_t block,
371                                                    unsigned size)
372 {
373         return __getblk_gfp(bdev, block, size, 0);
374 }
375 
376 static inline struct buffer_head *__getblk(struct block_device *bdev,
377                                            sector_t block,
378                                            unsigned size)
379 {
380         return __getblk_gfp(bdev, block, size, __GFP_MOVABLE);
381 }
382 
383 /**
384  *  __bread() - reads a specified block and returns the bh
385  *  @bdev: the block_device to read from
386  *  @block: number of block
387  *  @size: size (in bytes) to read
388  *
389  *  Reads a specified block, and returns buffer head that contains it.
390  *  The page cache is allocated from movable area so that it can be migrated.
391  *  It returns NULL if the block was unreadable.
392  */
393 static inline struct buffer_head *
394 __bread(struct block_device *bdev, sector_t block, unsigned size)
395 {
396         return __bread_gfp(bdev, block, size, __GFP_MOVABLE);
397 }
398 
399 extern int __set_page_dirty_buffers(struct page *page);
400 
401 #else /* CONFIG_BLOCK */
402 
403 static inline void buffer_init(void) {}
404 static inline int try_to_free_buffers(struct page *page) { return 1; }
405 static inline int inode_has_buffers(struct inode *inode) { return 0; }
406 static inline void invalidate_inode_buffers(struct inode *inode) {}
407 static inline int remove_inode_buffers(struct inode *inode) { return 1; }
408 static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
409 
410 #endif /* CONFIG_BLOCK */
411 #endif /* _LINUX_BUFFER_HEAD_H */
412 

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