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_Eopnotsupp, /* operation not supported (barrier) */
36 BH_Unwritten, /* Buffer is allocated on disk but not written */
37 BH_Quiet, /* Buffer Error Prinks to be quiet */
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(Eopnotsupp, eopnotsupp)
128 BUFFER_FNS(Unwritten, unwritten)
130 #define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK)
131 #define touch_buffer(bh) mark_page_accessed(bh->b_page)
133 /* If we *know* page->private refers to buffer_heads */
134 #define page_buffers(page) \
136 BUG_ON(!PagePrivate(page)); \
137 ((struct buffer_head *)page_private(page)); \
139 #define page_has_buffers(page) PagePrivate(page)
145 void mark_buffer_dirty(struct buffer_head *bh);
146 void init_buffer(struct buffer_head *, bh_end_io_t *, void *);
147 void set_bh_page(struct buffer_head *bh,
148 struct page *page, unsigned long offset);
149 int try_to_free_buffers(struct page *);
150 struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
152 void create_empty_buffers(struct page *, unsigned long,
153 unsigned long b_state);
154 void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
155 void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
156 void end_buffer_async_write(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 __wait_on_buffer(struct buffer_head *);
168 wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
169 struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block,
171 struct buffer_head *__getblk(struct block_device *bdev, sector_t block,
173 void __brelse(struct buffer_head *);
174 void __bforget(struct buffer_head *);
175 void __breadahead(struct block_device *, sector_t block, unsigned int size);
176 struct buffer_head *__bread(struct block_device *, sector_t block, unsigned size);
177 void invalidate_bh_lrus(void);
178 struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
179 void free_buffer_head(struct buffer_head * bh);
180 void unlock_buffer(struct buffer_head *bh);
181 void __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 __sync_dirty_buffer(struct buffer_head *bh, int rw);
185 void write_dirty_buffer(struct buffer_head *bh, int rw);
186 int submit_bh(int, struct buffer_head *);
187 void write_boundary_block(struct block_device *bdev,
188 sector_t bblock, unsigned blocksize);
189 int bh_uptodate_or_lock(struct buffer_head *bh);
190 int bh_submit_read(struct buffer_head *bh);
192 extern int buffer_heads_over_limit;
195 * Generic address_space_operations implementations for buffer_head-backed
198 void block_invalidatepage(struct page *page, unsigned long offset);
199 int block_write_full_page(struct page *page, get_block_t *get_block,
200 struct writeback_control *wbc);
201 int block_write_full_page_endio(struct page *page, get_block_t *get_block,
202 struct writeback_control *wbc, bh_end_io_t *handler);
203 int block_read_full_page(struct page*, get_block_t*);
204 int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc,
206 int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
207 unsigned flags, struct page **pagep, get_block_t *get_block);
208 int __block_write_begin(struct page *page, loff_t pos, unsigned len,
209 get_block_t *get_block);
210 int block_write_end(struct file *, struct address_space *,
211 loff_t, unsigned, unsigned,
212 struct page *, void *);
213 int generic_write_end(struct file *, struct address_space *,
214 loff_t, unsigned, unsigned,
215 struct page *, void *);
216 void page_zero_new_buffers(struct page *page, unsigned from, unsigned to);
217 int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
218 int cont_write_begin(struct file *, struct address_space *, loff_t,
219 unsigned, unsigned, struct page **, void **,
220 get_block_t *, loff_t *);
221 int generic_cont_expand_simple(struct inode *inode, loff_t size);
222 int block_commit_write(struct page *page, unsigned from, unsigned to);
223 int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
224 get_block_t get_block);
225 void block_sync_page(struct page *);
226 sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
227 int block_truncate_page(struct address_space *, loff_t, get_block_t *);
228 int nobh_write_begin(struct address_space *, loff_t, unsigned, unsigned,
229 struct page **, void **, get_block_t*);
230 int nobh_write_end(struct file *, struct address_space *,
231 loff_t, unsigned, unsigned,
232 struct page *, void *);
233 int nobh_truncate_page(struct address_space *, loff_t, get_block_t *);
234 int nobh_writepage(struct page *page, get_block_t *get_block,
235 struct writeback_control *wbc);
237 void buffer_init(void);
243 static inline void attach_page_buffers(struct page *page,
244 struct buffer_head *head)
246 page_cache_get(page);
247 SetPagePrivate(page);
248 set_page_private(page, (unsigned long)head);
251 static inline void get_bh(struct buffer_head *bh)
253 atomic_inc(&bh->b_count);
256 static inline void put_bh(struct buffer_head *bh)
258 smp_mb__before_atomic_dec();
259 atomic_dec(&bh->b_count);
262 static inline void brelse(struct buffer_head *bh)
268 static inline void bforget(struct buffer_head *bh)
274 static inline struct buffer_head *
275 sb_bread(struct super_block *sb, sector_t block)
277 return __bread(sb->s_bdev, block, sb->s_blocksize);
281 sb_breadahead(struct super_block *sb, sector_t block)
283 __breadahead(sb->s_bdev, block, sb->s_blocksize);
286 static inline struct buffer_head *
287 sb_getblk(struct super_block *sb, sector_t block)
289 return __getblk(sb->s_bdev, block, sb->s_blocksize);
292 static inline struct buffer_head *
293 sb_find_get_block(struct super_block *sb, sector_t block)
295 return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
299 map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
301 set_buffer_mapped(bh);
302 bh->b_bdev = sb->s_bdev;
303 bh->b_blocknr = block;
304 bh->b_size = sb->s_blocksize;
307 static inline void wait_on_buffer(struct buffer_head *bh)
310 if (buffer_locked(bh))
311 __wait_on_buffer(bh);
314 static inline int trylock_buffer(struct buffer_head *bh)
316 return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));
319 static inline void lock_buffer(struct buffer_head *bh)
322 if (!trylock_buffer(bh))
326 extern int __set_page_dirty_buffers(struct page *page);
328 #else /* CONFIG_BLOCK */
330 static inline void buffer_init(void) {}
331 static inline int try_to_free_buffers(struct page *page) { return 1; }
332 static inline int inode_has_buffers(struct inode *inode) { return 0; }
333 static inline void invalidate_inode_buffers(struct inode *inode) {}
334 static inline int remove_inode_buffers(struct inode *inode) { return 1; }
335 static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
337 #endif /* CONFIG_BLOCK */
338 #endif /* _LINUX_BUFFER_HEAD_H */