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/wait.h>
14 #include <asm/atomic.h>
17 BH_Uptodate, /* Contains valid data */
18 BH_Dirty, /* Is dirty */
19 BH_Lock, /* Is locked */
20 BH_Req, /* Has been submitted for I/O */
22 BH_Mapped, /* Has a disk mapping */
23 BH_New, /* Disk mapping was newly created by get_block */
24 BH_Async_Read, /* Is under end_buffer_async_read I/O */
25 BH_Async_Write, /* Is under end_buffer_async_write I/O */
26 BH_Delay, /* Buffer is not yet allocated on disk */
27 BH_Boundary, /* Block is followed by a discontiguity */
28 BH_Write_EIO, /* I/O error on write */
30 BH_PrivateStart,/* not a state bit, but the first bit available
31 * for private allocation by other entities
35 #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512)
40 typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
43 * Keep related fields in common cachelines. The most commonly accessed
44 * field (b_state) goes at the start so the compiler does not generate
45 * indexed addressing for it.
48 /* First cache line: */
49 unsigned long b_state; /* buffer state bitmap (see above) */
50 atomic_t b_count; /* users using this block */
51 struct buffer_head *b_this_page;/* circular list of page's buffers */
52 struct page *b_page; /* the page this bh is mapped to */
54 sector_t b_blocknr; /* block number */
55 u32 b_size; /* block size */
56 char *b_data; /* pointer to data block */
58 struct block_device *b_bdev;
59 bh_end_io_t *b_end_io; /* I/O completion */
60 void *b_private; /* reserved for b_end_io */
61 struct list_head b_assoc_buffers; /* associated with another mapping */
65 * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
66 * and buffer_foo() functions.
68 #define BUFFER_FNS(bit, name) \
69 static inline void set_buffer_##name(struct buffer_head *bh) \
71 set_bit(BH_##bit, &(bh)->b_state); \
73 static inline void clear_buffer_##name(struct buffer_head *bh) \
75 clear_bit(BH_##bit, &(bh)->b_state); \
77 static inline int buffer_##name(struct buffer_head *bh) \
79 return test_bit(BH_##bit, &(bh)->b_state); \
83 * test_set_buffer_foo() and test_clear_buffer_foo()
85 #define TAS_BUFFER_FNS(bit, name) \
86 static inline int test_set_buffer_##name(struct buffer_head *bh) \
88 return test_and_set_bit(BH_##bit, &(bh)->b_state); \
90 static inline int test_clear_buffer_##name(struct buffer_head *bh) \
92 return test_and_clear_bit(BH_##bit, &(bh)->b_state); \
96 * Emit the buffer bitops functions. Note that there are also functions
97 * of the form "mark_buffer_foo()". These are higher-level functions which
98 * do something in addition to setting a b_state bit.
100 BUFFER_FNS(Uptodate, uptodate)
101 BUFFER_FNS(Dirty, dirty)
102 TAS_BUFFER_FNS(Dirty, dirty)
103 BUFFER_FNS(Lock, locked)
104 TAS_BUFFER_FNS(Lock, locked)
106 TAS_BUFFER_FNS(Req, req)
107 BUFFER_FNS(Mapped, mapped)
109 BUFFER_FNS(Async_Read, async_read)
110 BUFFER_FNS(Async_Write, async_write)
111 BUFFER_FNS(Delay, delay)
112 BUFFER_FNS(Boundary, boundary)
113 BUFFER_FNS(Write_EIO,write_io_error)
115 #define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK)
116 #define touch_buffer(bh) mark_page_accessed(bh->b_page)
118 /* If we *know* page->private refers to buffer_heads */
119 #define page_buffers(page) \
121 BUG_ON(!PagePrivate(page)); \
122 ((struct buffer_head *)(page)->private); \
124 #define page_has_buffers(page) PagePrivate(page)
130 void FASTCALL(mark_buffer_dirty(struct buffer_head *bh));
131 void init_buffer(struct buffer_head *, bh_end_io_t *, void *);
132 void set_bh_page(struct buffer_head *bh,
133 struct page *page, unsigned long offset);
134 int try_to_free_buffers(struct page *);
135 void create_empty_buffers(struct page *, unsigned long,
136 unsigned long b_state);
137 void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
138 void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
139 void end_buffer_async_write(struct buffer_head *bh, int uptodate);
141 /* Things to do with buffers at mapping->private_list */
142 void buffer_insert_list(spinlock_t *lock,
143 struct buffer_head *, struct list_head *);
144 void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
145 int inode_has_buffers(struct inode *);
146 void invalidate_inode_buffers(struct inode *);
147 int remove_inode_buffers(struct inode *inode);
148 int fsync_buffers_list(spinlock_t *lock, struct list_head *);
149 int sync_mapping_buffers(struct address_space *mapping);
150 void unmap_underlying_metadata(struct block_device *bdev, sector_t block);
152 void mark_buffer_async_read(struct buffer_head *bh);
153 void mark_buffer_async_write(struct buffer_head *bh);
154 void invalidate_bdev(struct block_device *, int);
155 int sync_blockdev(struct block_device *bdev);
156 void __wait_on_buffer(struct buffer_head *);
157 wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
158 void wake_up_buffer(struct buffer_head *bh);
159 int fsync_bdev(struct block_device *);
160 struct super_block *freeze_bdev(struct block_device *);
161 void thaw_bdev(struct block_device *, struct super_block *);
162 int fsync_super(struct super_block *);
163 int fsync_no_super(struct block_device *);
164 struct buffer_head *__find_get_block(struct block_device *, sector_t, int);
165 struct buffer_head * __getblk(struct block_device *, sector_t, int);
166 void __brelse(struct buffer_head *);
167 void __bforget(struct buffer_head *);
168 void __breadahead(struct block_device *, sector_t block, int size);
169 struct buffer_head *__bread(struct block_device *, sector_t block, int size);
170 struct buffer_head *alloc_buffer_head(int gfp_flags);
171 void free_buffer_head(struct buffer_head * bh);
172 void FASTCALL(unlock_buffer(struct buffer_head *bh));
173 void FASTCALL(__lock_buffer(struct buffer_head *bh));
174 void ll_rw_block(int, int, struct buffer_head * bh[]);
175 void sync_dirty_buffer(struct buffer_head *bh);
176 void submit_bh(int, struct buffer_head *);
177 void write_boundary_block(struct block_device *bdev,
178 sector_t bblock, unsigned blocksize);
180 extern int buffer_heads_over_limit;
183 * Generic address_space_operations implementations for buffer_head-backed
186 int try_to_release_page(struct page * page, int gfp_mask);
187 int block_invalidatepage(struct page *page, unsigned long offset);
188 int block_write_full_page(struct page *page, get_block_t *get_block,
189 struct writeback_control *wbc);
190 int block_read_full_page(struct page*, get_block_t*);
191 int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
192 int cont_prepare_write(struct page*, unsigned, unsigned, get_block_t*,
194 int generic_cont_expand(struct inode *inode, loff_t size) ;
195 int block_commit_write(struct page *page, unsigned from, unsigned to);
196 int block_sync_page(struct page *);
197 sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
198 int generic_commit_write(struct file *, struct page *, unsigned, unsigned);
199 int block_truncate_page(struct address_space *, loff_t, get_block_t *);
200 int file_fsync(struct file *, struct dentry *, int);
201 int nobh_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
202 int nobh_commit_write(struct file *, struct page *, unsigned, unsigned);
203 int nobh_truncate_page(struct address_space *, loff_t);
205 #define OSYNC_METADATA (1<<0)
206 #define OSYNC_DATA (1<<1)
207 #define OSYNC_INODE (1<<2)
208 int generic_osync_inode(struct inode *, struct address_space *, int);
215 static inline void get_bh(struct buffer_head *bh)
217 atomic_inc(&bh->b_count);
220 static inline void put_bh(struct buffer_head *bh)
222 smp_mb__before_atomic_dec();
223 atomic_dec(&bh->b_count);
226 static inline void brelse(struct buffer_head *bh)
232 static inline void bforget(struct buffer_head *bh)
238 static inline struct buffer_head *
239 sb_bread(struct super_block *sb, sector_t block)
241 return __bread(sb->s_bdev, block, sb->s_blocksize);
245 sb_breadahead(struct super_block *sb, sector_t block)
247 __breadahead(sb->s_bdev, block, sb->s_blocksize);
250 static inline struct buffer_head *
251 sb_getblk(struct super_block *sb, sector_t block)
253 return __getblk(sb->s_bdev, block, sb->s_blocksize);
256 static inline struct buffer_head *
257 sb_find_get_block(struct super_block *sb, sector_t block)
259 return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
263 map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
265 set_buffer_mapped(bh);
266 bh->b_bdev = sb->s_bdev;
267 bh->b_blocknr = block;
271 * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into
272 * __wait_on_buffer() just to trip a debug check. Because debug code in inline
273 * functions is bloaty.
275 static inline void wait_on_buffer(struct buffer_head *bh)
277 if (buffer_locked(bh) || atomic_read(&bh->b_count) == 0)
278 __wait_on_buffer(bh);
281 static inline void lock_buffer(struct buffer_head *bh)
283 if (test_set_buffer_locked(bh))
287 #endif /* _LINUX_BUFFER_HEAD_H */