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 <linux/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_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 */
40 BH_PrivateStart
,/* not a state bit, but the first bit available
41 * for private allocation by other entities
45 #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512)
50 typedef void (bh_end_io_t
)(struct buffer_head
*bh
, int uptodate
);
53 * Historically, a buffer_head was used to map a single block
54 * within a page, and of course as the unit of I/O through the
55 * filesystem and block layers. Nowadays the basic I/O unit
56 * is the bio, and buffer_heads are used for extracting block
57 * mappings (via a get_block_t call), for tracking state within
58 * a page (via a page_mapping) and for wrapping bio submission
59 * for backward compatibility reasons (e.g. submit_bh).
62 unsigned long b_state
; /* buffer state bitmap (see above) */
63 struct buffer_head
*b_this_page
;/* circular list of page's buffers */
64 struct page
*b_page
; /* the page this bh is mapped to */
66 sector_t b_blocknr
; /* start block number */
67 size_t b_size
; /* size of mapping */
68 char *b_data
; /* pointer to data within the page */
70 struct block_device
*b_bdev
;
71 bh_end_io_t
*b_end_io
; /* I/O completion */
72 void *b_private
; /* reserved for b_end_io */
73 struct list_head b_assoc_buffers
; /* associated with another mapping */
74 struct address_space
*b_assoc_map
; /* mapping this buffer is
76 atomic_t b_count
; /* users using this buffer_head */
80 * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
81 * and buffer_foo() functions.
83 #define BUFFER_FNS(bit, name) \
84 static inline void set_buffer_##name(struct buffer_head *bh) \
86 set_bit(BH_##bit, &(bh)->b_state); \
88 static inline void clear_buffer_##name(struct buffer_head *bh) \
90 clear_bit(BH_##bit, &(bh)->b_state); \
92 static inline int buffer_##name(const struct buffer_head *bh) \
94 return test_bit(BH_##bit, &(bh)->b_state); \
98 * test_set_buffer_foo() and test_clear_buffer_foo()
100 #define TAS_BUFFER_FNS(bit, name) \
101 static inline int test_set_buffer_##name(struct buffer_head *bh) \
103 return test_and_set_bit(BH_##bit, &(bh)->b_state); \
105 static inline int test_clear_buffer_##name(struct buffer_head *bh) \
107 return test_and_clear_bit(BH_##bit, &(bh)->b_state); \
111 * Emit the buffer bitops functions. Note that there are also functions
112 * of the form "mark_buffer_foo()". These are higher-level functions which
113 * do something in addition to setting a b_state bit.
115 BUFFER_FNS(Uptodate
, uptodate
)
116 BUFFER_FNS(Dirty
, dirty
)
117 TAS_BUFFER_FNS(Dirty
, dirty
)
118 BUFFER_FNS(Lock
, locked
)
120 TAS_BUFFER_FNS(Req
, req
)
121 BUFFER_FNS(Mapped
, mapped
)
123 BUFFER_FNS(Async_Read
, async_read
)
124 BUFFER_FNS(Async_Write
, async_write
)
125 BUFFER_FNS(Delay
, delay
)
126 BUFFER_FNS(Boundary
, boundary
)
127 BUFFER_FNS(Write_EIO
, write_io_error
)
128 BUFFER_FNS(Unwritten
, unwritten
)
129 BUFFER_FNS(Meta
, meta
)
130 BUFFER_FNS(Prio
, prio
)
132 #define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK)
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 touch_buffer(struct buffer_head
*bh
);
149 void set_bh_page(struct buffer_head
*bh
,
150 struct page
*page
, unsigned long offset
);
151 int try_to_free_buffers(struct page
*);
152 struct buffer_head
*alloc_page_buffers(struct page
*page
, unsigned long size
,
154 void create_empty_buffers(struct page
*, unsigned long,
155 unsigned long b_state
);
156 void end_buffer_read_sync(struct buffer_head
*bh
, int uptodate
);
157 void end_buffer_write_sync(struct buffer_head
*bh
, int uptodate
);
158 void end_buffer_async_write(struct buffer_head
*bh
, int uptodate
);
160 /* Things to do with buffers at mapping->private_list */
161 void mark_buffer_dirty_inode(struct buffer_head
*bh
, struct inode
*inode
);
162 int inode_has_buffers(struct inode
*);
163 void invalidate_inode_buffers(struct inode
*);
164 int remove_inode_buffers(struct inode
*inode
);
165 int sync_mapping_buffers(struct address_space
*mapping
);
166 void unmap_underlying_metadata(struct block_device
*bdev
, sector_t block
);
168 void mark_buffer_async_write(struct buffer_head
*bh
);
169 void __wait_on_buffer(struct buffer_head
*);
170 wait_queue_head_t
*bh_waitq_head(struct buffer_head
*bh
);
171 struct buffer_head
*__find_get_block(struct block_device
*bdev
, sector_t block
,
173 struct buffer_head
*__getblk(struct block_device
*bdev
, sector_t block
,
175 void __brelse(struct buffer_head
*);
176 void __bforget(struct buffer_head
*);
177 void __breadahead(struct block_device
*, sector_t block
, unsigned int size
);
178 struct buffer_head
*__bread(struct block_device
*, sector_t block
, unsigned size
);
179 void invalidate_bh_lrus(void);
180 struct buffer_head
*alloc_buffer_head(gfp_t gfp_flags
);
181 void free_buffer_head(struct buffer_head
* bh
);
182 void unlock_buffer(struct buffer_head
*bh
);
183 void __lock_buffer(struct buffer_head
*bh
);
184 void ll_rw_block(int, int, struct buffer_head
* bh
[]);
185 int sync_dirty_buffer(struct buffer_head
*bh
);
186 int __sync_dirty_buffer(struct buffer_head
*bh
, int rw
);
187 void write_dirty_buffer(struct buffer_head
*bh
, int rw
);
188 int _submit_bh(int rw
, struct buffer_head
*bh
, unsigned long bio_flags
);
189 int submit_bh(int, struct buffer_head
*);
190 void write_boundary_block(struct block_device
*bdev
,
191 sector_t bblock
, unsigned blocksize
);
192 int bh_uptodate_or_lock(struct buffer_head
*bh
);
193 int bh_submit_read(struct buffer_head
*bh
);
195 extern int buffer_heads_over_limit
;
198 * Generic address_space_operations implementations for buffer_head-backed
201 void block_invalidatepage(struct page
*page
, unsigned long offset
);
202 int block_write_full_page(struct page
*page
, get_block_t
*get_block
,
203 struct writeback_control
*wbc
);
204 int block_write_full_page_endio(struct page
*page
, get_block_t
*get_block
,
205 struct writeback_control
*wbc
, bh_end_io_t
*handler
);
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 address_space
*mapping
, loff_t pos
, unsigned len
,
210 unsigned flags
, struct page
**pagep
, get_block_t
*get_block
);
211 int __block_write_begin(struct page
*page
, loff_t pos
, unsigned len
,
212 get_block_t
*get_block
);
213 int block_write_end(struct file
*, struct address_space
*,
214 loff_t
, unsigned, unsigned,
215 struct page
*, void *);
216 int generic_write_end(struct file
*, struct address_space
*,
217 loff_t
, unsigned, unsigned,
218 struct page
*, void *);
219 void page_zero_new_buffers(struct page
*page
, unsigned from
, unsigned to
);
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 vm_fault
*vmf
,
226 get_block_t get_block
);
227 int block_page_mkwrite(struct vm_area_struct
*vma
, struct vm_fault
*vmf
,
228 get_block_t get_block
);
229 /* Convert errno to return value from ->page_mkwrite() call */
230 static inline int block_page_mkwrite_return(int err
)
233 return VM_FAULT_LOCKED
;
235 return VM_FAULT_NOPAGE
;
239 return VM_FAULT_RETRY
;
240 /* -ENOSPC, -EDQUOT, -EIO ... */
241 return VM_FAULT_SIGBUS
;
243 sector_t
generic_block_bmap(struct address_space
*, sector_t
, get_block_t
*);
244 int block_truncate_page(struct address_space
*, loff_t
, get_block_t
*);
245 int nobh_write_begin(struct address_space
*, loff_t
, unsigned, unsigned,
246 struct page
**, void **, get_block_t
*);
247 int nobh_write_end(struct file
*, struct address_space
*,
248 loff_t
, unsigned, unsigned,
249 struct page
*, void *);
250 int nobh_truncate_page(struct address_space
*, loff_t
, get_block_t
*);
251 int nobh_writepage(struct page
*page
, get_block_t
*get_block
,
252 struct writeback_control
*wbc
);
254 void buffer_init(void);
260 static inline void attach_page_buffers(struct page
*page
,
261 struct buffer_head
*head
)
263 page_cache_get(page
);
264 SetPagePrivate(page
);
265 set_page_private(page
, (unsigned long)head
);
268 static inline void get_bh(struct buffer_head
*bh
)
270 atomic_inc(&bh
->b_count
);
273 static inline void put_bh(struct buffer_head
*bh
)
275 smp_mb__before_atomic_dec();
276 atomic_dec(&bh
->b_count
);
279 static inline void brelse(struct buffer_head
*bh
)
285 static inline void bforget(struct buffer_head
*bh
)
291 static inline struct buffer_head
*
292 sb_bread(struct super_block
*sb
, sector_t block
)
294 return __bread(sb
->s_bdev
, block
, sb
->s_blocksize
);
298 sb_breadahead(struct super_block
*sb
, sector_t block
)
300 __breadahead(sb
->s_bdev
, block
, sb
->s_blocksize
);
303 static inline struct buffer_head
*
304 sb_getblk(struct super_block
*sb
, sector_t block
)
306 return __getblk(sb
->s_bdev
, block
, sb
->s_blocksize
);
309 static inline struct buffer_head
*
310 sb_find_get_block(struct super_block
*sb
, sector_t block
)
312 return __find_get_block(sb
->s_bdev
, block
, sb
->s_blocksize
);
316 map_bh(struct buffer_head
*bh
, struct super_block
*sb
, sector_t block
)
318 set_buffer_mapped(bh
);
319 bh
->b_bdev
= sb
->s_bdev
;
320 bh
->b_blocknr
= block
;
321 bh
->b_size
= sb
->s_blocksize
;
324 static inline void wait_on_buffer(struct buffer_head
*bh
)
327 if (buffer_locked(bh
))
328 __wait_on_buffer(bh
);
331 static inline int trylock_buffer(struct buffer_head
*bh
)
333 return likely(!test_and_set_bit_lock(BH_Lock
, &bh
->b_state
));
336 static inline void lock_buffer(struct buffer_head
*bh
)
339 if (!trylock_buffer(bh
))
343 extern int __set_page_dirty_buffers(struct page
*page
);
345 #else /* CONFIG_BLOCK */
347 static inline void buffer_init(void) {}
348 static inline int try_to_free_buffers(struct page
*page
) { return 1; }
349 static inline int inode_has_buffers(struct inode
*inode
) { return 0; }
350 static inline void invalidate_inode_buffers(struct inode
*inode
) {}
351 static inline int remove_inode_buffers(struct inode
*inode
) { return 1; }
352 static inline int sync_mapping_buffers(struct address_space
*mapping
) { return 0; }
354 #endif /* CONFIG_BLOCK */
355 #endif /* _LINUX_BUFFER_HEAD_H */