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 */
38 BH_Quiet, /* Buffer Error Prinks to be quiet */
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(Ordered, ordered)
129 BUFFER_FNS(Eopnotsupp, eopnotsupp)
130 BUFFER_FNS(Unwritten, unwritten)
132 #define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK)
133 #define touch_buffer(bh) mark_page_accessed(bh->b_page)
135 /* If we *know* page->private refers to buffer_heads */
136 #define page_buffers(page) \
138 BUG_ON(!PagePrivate(page)); \
139 ((struct buffer_head *)page_private(page)); \
141 #define page_has_buffers(page) PagePrivate(page)
147 void mark_buffer_dirty(struct buffer_head *bh);
148 void init_buffer(struct buffer_head *, bh_end_io_t *, void *);
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 int __wait_on_buffer_async(struct buffer_head *, struct wait_bit_queue *);
171 wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
172 struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block,
174 struct buffer_head *__getblk(struct block_device *bdev, sector_t block,
176 void __brelse(struct buffer_head *);
177 void __bforget(struct buffer_head *);
178 void __breadahead(struct block_device *, sector_t block, unsigned int size);
179 struct buffer_head *__bread(struct block_device *, sector_t block, unsigned size);
180 void invalidate_bh_lrus(void);
181 struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
182 void free_buffer_head(struct buffer_head * bh);
183 void unlock_buffer(struct buffer_head *bh);
184 void __lock_buffer(struct buffer_head *bh);
185 void ll_rw_block(int, int, struct buffer_head * bh[]);
186 int sync_dirty_buffer(struct buffer_head *bh);
187 int submit_bh(int, struct buffer_head *);
188 void write_boundary_block(struct block_device *bdev,
189 sector_t bblock, unsigned blocksize);
190 int bh_uptodate_or_lock(struct buffer_head *bh);
191 int bh_submit_read(struct buffer_head *bh);
193 extern int buffer_heads_over_limit;
196 * Generic address_space_operations implementations for buffer_head-backed
199 void block_invalidatepage(struct page *page, unsigned long offset);
200 int block_write_full_page(struct page *page, get_block_t *get_block,
201 struct writeback_control *wbc);
202 int block_write_full_page_endio(struct page *page, get_block_t *get_block,
203 struct writeback_control *wbc, bh_end_io_t *handler);
204 int block_read_full_page(struct page*, get_block_t*);
205 int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc,
207 int block_write_begin(struct file *, struct address_space *,
208 loff_t, unsigned, unsigned,
209 struct page **, void **, get_block_t*);
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 file_fsync(struct file *, struct dentry *, int);
229 int nobh_write_begin(struct file *, struct address_space *,
230 loff_t, unsigned, unsigned,
231 struct page **, void **, get_block_t*);
232 int nobh_write_end(struct file *, struct address_space *,
233 loff_t, unsigned, unsigned,
234 struct page *, void *);
235 int nobh_truncate_page(struct address_space *, loff_t, get_block_t *);
236 int nobh_writepage(struct page *page, get_block_t *get_block,
237 struct writeback_control *wbc);
239 void buffer_init(void);
245 static inline void attach_page_buffers(struct page *page,
246 struct buffer_head *head)
248 page_cache_get(page);
249 SetPagePrivate(page);
250 set_page_private(page, (unsigned long)head);
253 static inline void get_bh(struct buffer_head *bh)
255 atomic_inc(&bh->b_count);
258 static inline void put_bh(struct buffer_head *bh)
260 smp_mb__before_atomic_dec();
261 atomic_dec(&bh->b_count);
264 static inline void brelse(struct buffer_head *bh)
270 static inline void bforget(struct buffer_head *bh)
276 static inline struct buffer_head *
277 sb_bread(struct super_block *sb, sector_t block)
279 return __bread(sb->s_bdev, block, sb->s_blocksize);
283 sb_breadahead(struct super_block *sb, sector_t block)
285 __breadahead(sb->s_bdev, block, sb->s_blocksize);
288 static inline struct buffer_head *
289 sb_getblk(struct super_block *sb, sector_t block)
291 return __getblk(sb->s_bdev, block, sb->s_blocksize);
294 static inline struct buffer_head *
295 sb_find_get_block(struct super_block *sb, sector_t block)
297 return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
301 map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
303 set_buffer_mapped(bh);
304 bh->b_bdev = sb->s_bdev;
305 bh->b_blocknr = block;
306 bh->b_size = sb->s_blocksize;
310 * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into
311 * __wait_on_buffer() just to trip a debug check. Because debug code in inline
312 * functions is bloaty.
314 static inline void wait_on_buffer(struct buffer_head *bh)
317 if (buffer_locked(bh) || atomic_read(&bh->b_count) == 0)
318 __wait_on_buffer(bh);
321 static inline int wait_on_buffer_async(struct buffer_head *bh,
322 struct wait_bit_queue *wait)
324 if (buffer_locked(bh) || atomic_read(&bh->b_count) == 0)
325 return __wait_on_buffer_async(bh, wait);
330 static inline int trylock_buffer(struct buffer_head *bh)
332 return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));
335 static inline void lock_buffer(struct buffer_head *bh)
338 if (!trylock_buffer(bh))
342 extern int __set_page_dirty_buffers(struct page *page);
344 #else /* CONFIG_BLOCK */
346 static inline void buffer_init(void) {}
347 static inline int try_to_free_buffers(struct page *page) { return 1; }
348 static inline int inode_has_buffers(struct inode *inode) { return 0; }
349 static inline void invalidate_inode_buffers(struct inode *inode) {}
350 static inline int remove_inode_buffers(struct inode *inode) { return 1; }
351 static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
353 #endif /* CONFIG_BLOCK */
354 #endif /* _LINUX_BUFFER_HEAD_H */