2 * include/linux/buffer_head.h
4 * Everything to do with buffer_heads.
7 #ifndef _LINUX_BUFFER_HEAD_H
8 #define _LINUX_BUFFER_HEAD_H
10 #include <linux/types.h>
12 #include <linux/linkage.h>
13 #include <linux/pagemap.h>
14 #include <linux/wait.h>
15 #include <asm/atomic.h>
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
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) */
37 BH_Unwritten
, /* Buffer is allocated on disk but not written */
39 BH_PrivateStart
,/* not a state bit, but the first bit available
40 * for private allocation by other entities
44 #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512)
49 typedef void (bh_end_io_t
)(struct buffer_head
*bh
, int uptodate
);
52 * Historically, a buffer_head was used to map a single block
53 * within a page, and of course as the unit of I/O through the
54 * filesystem and block layers. Nowadays the basic I/O unit
55 * is the bio, and buffer_heads are used for extracting block
56 * mappings (via a get_block_t call), for tracking state within
57 * a page (via a page_mapping) and for wrapping bio submission
58 * for backward compatibility reasons (e.g. submit_bh).
61 unsigned long b_state
; /* buffer state bitmap (see above) */
62 struct buffer_head
*b_this_page
;/* circular list of page's buffers */
63 struct page
*b_page
; /* the page this bh is mapped to */
65 sector_t b_blocknr
; /* start block number */
66 size_t b_size
; /* size of mapping */
67 char *b_data
; /* pointer to data within the page */
69 struct block_device
*b_bdev
;
70 bh_end_io_t
*b_end_io
; /* I/O completion */
71 void *b_private
; /* reserved for b_end_io */
72 struct list_head b_assoc_buffers
; /* associated with another mapping */
73 struct address_space
*b_assoc_map
; /* mapping this buffer is
75 atomic_t b_count
; /* users using this buffer_head */
79 * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
80 * and buffer_foo() functions.
82 #define BUFFER_FNS(bit, name) \
83 static inline void set_buffer_##name(struct buffer_head *bh) \
85 set_bit(BH_##bit, &(bh)->b_state); \
87 static inline void clear_buffer_##name(struct buffer_head *bh) \
89 clear_bit(BH_##bit, &(bh)->b_state); \
91 static inline int buffer_##name(const struct buffer_head *bh) \
93 return test_bit(BH_##bit, &(bh)->b_state); \
97 * test_set_buffer_foo() and test_clear_buffer_foo()
99 #define TAS_BUFFER_FNS(bit, name) \
100 static inline int test_set_buffer_##name(struct buffer_head *bh) \
102 return test_and_set_bit(BH_##bit, &(bh)->b_state); \
104 static inline int test_clear_buffer_##name(struct buffer_head *bh) \
106 return test_and_clear_bit(BH_##bit, &(bh)->b_state); \
110 * Emit the buffer bitops functions. Note that there are also functions
111 * of the form "mark_buffer_foo()". These are higher-level functions which
112 * do something in addition to setting a b_state bit.
114 BUFFER_FNS(Uptodate
, uptodate
)
115 BUFFER_FNS(Dirty
, dirty
)
116 TAS_BUFFER_FNS(Dirty
, dirty
)
117 BUFFER_FNS(Lock
, locked
)
119 TAS_BUFFER_FNS(Req
, req
)
120 BUFFER_FNS(Mapped
, mapped
)
122 BUFFER_FNS(Async_Read
, async_read
)
123 BUFFER_FNS(Async_Write
, async_write
)
124 BUFFER_FNS(Delay
, delay
)
125 BUFFER_FNS(Boundary
, boundary
)
126 BUFFER_FNS(Write_EIO
, write_io_error
)
127 BUFFER_FNS(Ordered
, ordered
)
128 BUFFER_FNS(Eopnotsupp
, eopnotsupp
)
129 BUFFER_FNS(Unwritten
, unwritten
)
131 #define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK)
132 #define touch_buffer(bh) mark_page_accessed(bh->b_page)
134 /* If we *know* page->private refers to buffer_heads */
135 #define page_buffers(page) \
137 BUG_ON(!PagePrivate(page)); \
138 ((struct buffer_head *)page_private(page)); \
140 #define page_has_buffers(page) PagePrivate(page)
146 void mark_buffer_dirty(struct buffer_head
*bh
);
147 void init_buffer(struct buffer_head
*, bh_end_io_t
*, void *);
148 void set_bh_page(struct buffer_head
*bh
,
149 struct page
*page
, unsigned long offset
);
150 int try_to_free_buffers(struct page
*);
151 struct buffer_head
*alloc_page_buffers(struct page
*page
, unsigned long size
,
153 void create_empty_buffers(struct page
*, unsigned long,
154 unsigned long b_state
);
155 void end_buffer_read_sync(struct buffer_head
*bh
, int uptodate
);
156 void end_buffer_write_sync(struct buffer_head
*bh
, int uptodate
);
158 /* Things to do with buffers at mapping->private_list */
159 void mark_buffer_dirty_inode(struct buffer_head
*bh
, struct inode
*inode
);
160 int inode_has_buffers(struct inode
*);
161 void invalidate_inode_buffers(struct inode
*);
162 int remove_inode_buffers(struct inode
*inode
);
163 int sync_mapping_buffers(struct address_space
*mapping
);
164 void unmap_underlying_metadata(struct block_device
*bdev
, sector_t block
);
166 void mark_buffer_async_write(struct buffer_head
*bh
);
167 void invalidate_bdev(struct block_device
*);
168 int sync_blockdev(struct block_device
*bdev
);
169 void __wait_on_buffer(struct buffer_head
*);
170 wait_queue_head_t
*bh_waitq_head(struct buffer_head
*bh
);
171 int fsync_bdev(struct block_device
*);
172 struct super_block
*freeze_bdev(struct block_device
*);
173 void thaw_bdev(struct block_device
*, struct super_block
*);
174 int fsync_super(struct super_block
*);
175 int fsync_no_super(struct block_device
*);
176 struct buffer_head
*__find_get_block(struct block_device
*bdev
, sector_t block
,
178 struct buffer_head
*__getblk(struct block_device
*bdev
, sector_t block
,
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 submit_bh(int, struct buffer_head
*);
192 void write_boundary_block(struct block_device
*bdev
,
193 sector_t bblock
, unsigned blocksize
);
194 int bh_uptodate_or_lock(struct buffer_head
*bh
);
195 int bh_submit_read(struct buffer_head
*bh
);
197 extern int buffer_heads_over_limit
;
200 * Generic address_space_operations implementations for buffer_head-backed
203 void block_invalidatepage(struct page
*page
, unsigned long offset
);
204 int block_write_full_page(struct page
*page
, get_block_t
*get_block
,
205 struct writeback_control
*wbc
);
206 int block_read_full_page(struct page
*, get_block_t
*);
207 int block_is_partially_uptodate(struct page
*page
, read_descriptor_t
*desc
,
209 int block_write_begin(struct file
*, struct address_space
*,
210 loff_t
, unsigned, unsigned,
211 struct page
**, void **, get_block_t
*);
212 int block_write_end(struct file
*, struct address_space
*,
213 loff_t
, unsigned, unsigned,
214 struct page
*, void *);
215 int generic_write_end(struct file
*, struct address_space
*,
216 loff_t
, unsigned, unsigned,
217 struct page
*, void *);
218 void page_zero_new_buffers(struct page
*page
, unsigned from
, unsigned to
);
219 int block_prepare_write(struct page
*, unsigned, unsigned, get_block_t
*);
220 int cont_write_begin(struct file
*, struct address_space
*, loff_t
,
221 unsigned, unsigned, struct page
**, void **,
222 get_block_t
*, loff_t
*);
223 int generic_cont_expand_simple(struct inode
*inode
, loff_t size
);
224 int block_commit_write(struct page
*page
, unsigned from
, unsigned to
);
225 int block_page_mkwrite(struct vm_area_struct
*vma
, struct page
*page
,
226 get_block_t get_block
);
227 void block_sync_page(struct page
*);
228 sector_t
generic_block_bmap(struct address_space
*, sector_t
, get_block_t
*);
229 int block_truncate_page(struct address_space
*, loff_t
, get_block_t
*);
230 int file_fsync(struct file
*, struct dentry
*, int);
231 int nobh_write_begin(struct file
*, struct address_space
*,
232 loff_t
, unsigned, unsigned,
233 struct page
**, void **, get_block_t
*);
234 int nobh_write_end(struct file
*, struct address_space
*,
235 loff_t
, unsigned, unsigned,
236 struct page
*, void *);
237 int nobh_truncate_page(struct address_space
*, loff_t
, get_block_t
*);
238 int nobh_writepage(struct page
*page
, get_block_t
*get_block
,
239 struct writeback_control
*wbc
);
241 void buffer_init(void);
247 static inline void attach_page_buffers(struct page
*page
,
248 struct buffer_head
*head
)
250 page_cache_get(page
);
251 SetPagePrivate(page
);
252 set_page_private(page
, (unsigned long)head
);
255 static inline void get_bh(struct buffer_head
*bh
)
257 atomic_inc(&bh
->b_count
);
260 static inline void put_bh(struct buffer_head
*bh
)
262 smp_mb__before_atomic_dec();
263 atomic_dec(&bh
->b_count
);
266 static inline void brelse(struct buffer_head
*bh
)
272 static inline void bforget(struct buffer_head
*bh
)
278 static inline struct buffer_head
*
279 sb_bread(struct super_block
*sb
, sector_t block
)
281 return __bread(sb
->s_bdev
, block
, sb
->s_blocksize
);
285 sb_breadahead(struct super_block
*sb
, sector_t block
)
287 __breadahead(sb
->s_bdev
, block
, sb
->s_blocksize
);
290 static inline struct buffer_head
*
291 sb_getblk(struct super_block
*sb
, sector_t block
)
293 return __getblk(sb
->s_bdev
, block
, sb
->s_blocksize
);
296 static inline struct buffer_head
*
297 sb_find_get_block(struct super_block
*sb
, sector_t block
)
299 return __find_get_block(sb
->s_bdev
, block
, sb
->s_blocksize
);
303 map_bh(struct buffer_head
*bh
, struct super_block
*sb
, sector_t block
)
305 set_buffer_mapped(bh
);
306 bh
->b_bdev
= sb
->s_bdev
;
307 bh
->b_blocknr
= block
;
308 bh
->b_size
= sb
->s_blocksize
;
312 * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into
313 * __wait_on_buffer() just to trip a debug check. Because debug code in inline
314 * functions is bloaty.
316 static inline void wait_on_buffer(struct buffer_head
*bh
)
319 if (buffer_locked(bh
) || atomic_read(&bh
->b_count
) == 0)
320 __wait_on_buffer(bh
);
323 static inline int trylock_buffer(struct buffer_head
*bh
)
325 return likely(!test_and_set_bit(BH_Lock
, &bh
->b_state
));
328 static inline void lock_buffer(struct buffer_head
*bh
)
331 if (!trylock_buffer(bh
))
335 extern int __set_page_dirty_buffers(struct page
*page
);
337 #else /* CONFIG_BLOCK */
339 static inline void buffer_init(void) {}
340 static inline int try_to_free_buffers(struct page
*page
) { return 1; }
341 static inline int sync_blockdev(struct block_device
*bdev
) { return 0; }
342 static inline int inode_has_buffers(struct inode
*inode
) { return 0; }
343 static inline void invalidate_inode_buffers(struct inode
*inode
) {}
344 static inline int remove_inode_buffers(struct inode
*inode
) { return 1; }
345 static inline int sync_mapping_buffers(struct address_space
*mapping
) { return 0; }
346 static inline void invalidate_bdev(struct block_device
*bdev
) {}
349 #endif /* CONFIG_BLOCK */
350 #endif /* _LINUX_BUFFER_HEAD_H */