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>
18 BH_Uptodate
, /* Contains valid data */
19 BH_Dirty
, /* Is dirty */
20 BH_Lock
, /* Is locked */
21 BH_Req
, /* Has been submitted for I/O */
22 BH_Uptodate_Lock
,/* Used by the first bh in a page, to serialise
23 * IO completion of other buffers in the page
26 BH_Mapped
, /* Has a disk mapping */
27 BH_New
, /* Disk mapping was newly created by get_block */
28 BH_Async_Read
, /* Is under end_buffer_async_read I/O */
29 BH_Async_Write
, /* Is under end_buffer_async_write I/O */
30 BH_Delay
, /* Buffer is not yet allocated on disk */
31 BH_Boundary
, /* Block is followed by a discontiguity */
32 BH_Write_EIO
, /* I/O error on write */
33 BH_Ordered
, /* ordered write */
34 BH_Eopnotsupp
, /* operation not supported (barrier) */
36 BH_PrivateStart
,/* not a state bit, but the first bit available
37 * for private allocation by other entities
41 #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512)
46 typedef void (bh_end_io_t
)(struct buffer_head
*bh
, int uptodate
);
49 * Historically, a buffer_head was used to map a single block
50 * within a page, and of course as the unit of I/O through the
51 * filesystem and block layers. Nowadays the basic I/O unit
52 * is the bio, and buffer_heads are used for extracting block
53 * mappings (via a get_block_t call), for tracking state within
54 * a page (via a page_mapping) and for wrapping bio submission
55 * for backward compatibility reasons (e.g. submit_bh).
58 unsigned long b_state
; /* buffer state bitmap (see above) */
59 struct buffer_head
*b_this_page
;/* circular list of page's buffers */
60 struct page
*b_page
; /* the page this bh is mapped to */
62 sector_t b_blocknr
; /* start block number */
63 size_t b_size
; /* size of mapping */
64 char *b_data
; /* pointer to data within the page */
66 struct block_device
*b_bdev
;
67 bh_end_io_t
*b_end_io
; /* I/O completion */
68 void *b_private
; /* reserved for b_end_io */
69 struct list_head b_assoc_buffers
; /* associated with another mapping */
70 atomic_t b_count
; /* users using this buffer_head */
74 * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
75 * and buffer_foo() functions.
77 #define BUFFER_FNS(bit, name) \
78 static inline void set_buffer_##name(struct buffer_head *bh) \
80 set_bit(BH_##bit, &(bh)->b_state); \
82 static inline void clear_buffer_##name(struct buffer_head *bh) \
84 clear_bit(BH_##bit, &(bh)->b_state); \
86 static inline int buffer_##name(const struct buffer_head *bh) \
88 return test_bit(BH_##bit, &(bh)->b_state); \
92 * test_set_buffer_foo() and test_clear_buffer_foo()
94 #define TAS_BUFFER_FNS(bit, name) \
95 static inline int test_set_buffer_##name(struct buffer_head *bh) \
97 return test_and_set_bit(BH_##bit, &(bh)->b_state); \
99 static inline int test_clear_buffer_##name(struct buffer_head *bh) \
101 return test_and_clear_bit(BH_##bit, &(bh)->b_state); \
105 * Emit the buffer bitops functions. Note that there are also functions
106 * of the form "mark_buffer_foo()". These are higher-level functions which
107 * do something in addition to setting a b_state bit.
109 BUFFER_FNS(Uptodate
, uptodate
)
110 BUFFER_FNS(Dirty
, dirty
)
111 TAS_BUFFER_FNS(Dirty
, dirty
)
112 BUFFER_FNS(Lock
, locked
)
113 TAS_BUFFER_FNS(Lock
, locked
)
115 TAS_BUFFER_FNS(Req
, req
)
116 BUFFER_FNS(Mapped
, mapped
)
118 BUFFER_FNS(Async_Read
, async_read
)
119 BUFFER_FNS(Async_Write
, async_write
)
120 BUFFER_FNS(Delay
, delay
)
121 BUFFER_FNS(Boundary
, boundary
)
122 BUFFER_FNS(Write_EIO
, write_io_error
)
123 BUFFER_FNS(Ordered
, ordered
)
124 BUFFER_FNS(Eopnotsupp
, eopnotsupp
)
126 #define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK)
127 #define touch_buffer(bh) mark_page_accessed(bh->b_page)
129 /* If we *know* page->private refers to buffer_heads */
130 #define page_buffers(page) \
132 BUG_ON(!PagePrivate(page)); \
133 ((struct buffer_head *)page_private(page)); \
135 #define page_has_buffers(page) PagePrivate(page)
141 void FASTCALL(mark_buffer_dirty(struct buffer_head
*bh
));
142 void init_buffer(struct buffer_head
*, bh_end_io_t
*, void *);
143 void set_bh_page(struct buffer_head
*bh
,
144 struct page
*page
, unsigned long offset
);
145 int try_to_free_buffers(struct page
*);
146 struct buffer_head
*alloc_page_buffers(struct page
*page
, unsigned long size
,
148 void create_empty_buffers(struct page
*, unsigned long,
149 unsigned long b_state
);
150 void end_buffer_read_sync(struct buffer_head
*bh
, int uptodate
);
151 void end_buffer_write_sync(struct buffer_head
*bh
, int uptodate
);
152 void end_buffer_async_write(struct buffer_head
*bh
, int uptodate
);
154 /* Things to do with buffers at mapping->private_list */
155 void mark_buffer_dirty_inode(struct buffer_head
*bh
, struct inode
*inode
);
156 int inode_has_buffers(struct inode
*);
157 void invalidate_inode_buffers(struct inode
*);
158 int remove_inode_buffers(struct inode
*inode
);
159 int sync_mapping_buffers(struct address_space
*mapping
);
160 void unmap_underlying_metadata(struct block_device
*bdev
, sector_t block
);
162 void mark_buffer_async_write(struct buffer_head
*bh
);
163 void invalidate_bdev(struct block_device
*, int);
164 int sync_blockdev(struct block_device
*bdev
);
165 void __wait_on_buffer(struct buffer_head
*);
166 wait_queue_head_t
*bh_waitq_head(struct buffer_head
*bh
);
167 int fsync_bdev(struct block_device
*);
168 struct super_block
*freeze_bdev(struct block_device
*);
169 void thaw_bdev(struct block_device
*, struct super_block
*);
170 int fsync_super(struct super_block
*);
171 int fsync_no_super(struct block_device
*);
172 struct buffer_head
*__find_get_block(struct block_device
*, sector_t
, int);
173 struct buffer_head
* __getblk(struct block_device
*, sector_t
, int);
174 void __brelse(struct buffer_head
*);
175 void __bforget(struct buffer_head
*);
176 void __breadahead(struct block_device
*, sector_t block
, int size
);
177 struct buffer_head
*__bread(struct block_device
*, sector_t block
, int size
);
178 struct buffer_head
*alloc_buffer_head(gfp_t gfp_flags
);
179 void free_buffer_head(struct buffer_head
* bh
);
180 void FASTCALL(unlock_buffer(struct buffer_head
*bh
));
181 void FASTCALL(__lock_buffer(struct buffer_head
*bh
));
182 void ll_rw_block(int, int, struct buffer_head
* bh
[]);
183 int sync_dirty_buffer(struct buffer_head
*bh
);
184 int submit_bh(int, struct buffer_head
*);
185 void write_boundary_block(struct block_device
*bdev
,
186 sector_t bblock
, unsigned blocksize
);
188 extern int buffer_heads_over_limit
;
191 * Generic address_space_operations implementations for buffer_head-backed
194 int try_to_release_page(struct page
* page
, gfp_t gfp_mask
);
195 void block_invalidatepage(struct page
*page
, unsigned long offset
);
196 void do_invalidatepage(struct page
*page
, unsigned long offset
);
197 int block_write_full_page(struct page
*page
, get_block_t
*get_block
,
198 struct writeback_control
*wbc
);
199 int block_read_full_page(struct page
*, get_block_t
*);
200 int block_prepare_write(struct page
*, unsigned, unsigned, get_block_t
*);
201 int cont_prepare_write(struct page
*, unsigned, unsigned, get_block_t
*,
203 int generic_cont_expand(struct inode
*inode
, loff_t size
);
204 int generic_cont_expand_simple(struct inode
*inode
, loff_t size
);
205 int block_commit_write(struct page
*page
, unsigned from
, unsigned to
);
206 void block_sync_page(struct page
*);
207 sector_t
generic_block_bmap(struct address_space
*, sector_t
, get_block_t
*);
208 int generic_commit_write(struct file
*, struct page
*, unsigned, unsigned);
209 int block_truncate_page(struct address_space
*, loff_t
, get_block_t
*);
210 int file_fsync(struct file
*, struct dentry
*, int);
211 int nobh_prepare_write(struct page
*, unsigned, unsigned, get_block_t
*);
212 int nobh_commit_write(struct file
*, struct page
*, unsigned, unsigned);
213 int nobh_truncate_page(struct address_space
*, loff_t
);
214 int nobh_writepage(struct page
*page
, get_block_t
*get_block
,
215 struct writeback_control
*wbc
);
222 static inline void attach_page_buffers(struct page
*page
,
223 struct buffer_head
*head
)
225 page_cache_get(page
);
226 SetPagePrivate(page
);
227 set_page_private(page
, (unsigned long)head
);
230 static inline void get_bh(struct buffer_head
*bh
)
232 atomic_inc(&bh
->b_count
);
235 static inline void put_bh(struct buffer_head
*bh
)
237 smp_mb__before_atomic_dec();
238 atomic_dec(&bh
->b_count
);
241 static inline void brelse(struct buffer_head
*bh
)
247 static inline void bforget(struct buffer_head
*bh
)
253 static inline struct buffer_head
*
254 sb_bread(struct super_block
*sb
, sector_t block
)
256 return __bread(sb
->s_bdev
, block
, sb
->s_blocksize
);
260 sb_breadahead(struct super_block
*sb
, sector_t block
)
262 __breadahead(sb
->s_bdev
, block
, sb
->s_blocksize
);
265 static inline struct buffer_head
*
266 sb_getblk(struct super_block
*sb
, sector_t block
)
268 return __getblk(sb
->s_bdev
, block
, sb
->s_blocksize
);
271 static inline struct buffer_head
*
272 sb_find_get_block(struct super_block
*sb
, sector_t block
)
274 return __find_get_block(sb
->s_bdev
, block
, sb
->s_blocksize
);
278 map_bh(struct buffer_head
*bh
, struct super_block
*sb
, sector_t block
)
280 set_buffer_mapped(bh
);
281 bh
->b_bdev
= sb
->s_bdev
;
282 bh
->b_blocknr
= block
;
283 bh
->b_size
= sb
->s_blocksize
;
287 * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into
288 * __wait_on_buffer() just to trip a debug check. Because debug code in inline
289 * functions is bloaty.
291 static inline void wait_on_buffer(struct buffer_head
*bh
)
294 if (buffer_locked(bh
) || atomic_read(&bh
->b_count
) == 0)
295 __wait_on_buffer(bh
);
298 static inline void lock_buffer(struct buffer_head
*bh
)
301 if (test_set_buffer_locked(bh
))
305 #endif /* _LINUX_BUFFER_HEAD_H */