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 int offset,
202 unsigned int length);
203 int block_write_full_page(struct page *page, get_block_t *get_block,
204 struct writeback_control *wbc);
205 int block_write_full_page_endio(struct page *page, get_block_t *get_block,
206 struct writeback_control *wbc, bh_end_io_t *handler);
207 int block_read_full_page(struct page*, get_block_t*);
208 int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc,
210 int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
211 unsigned flags, struct page **pagep, get_block_t *get_block);
212 int __block_write_begin(struct page *page, loff_t pos, unsigned len,
213 get_block_t *get_block);
214 int block_write_end(struct file *, struct address_space *,
215 loff_t, unsigned, unsigned,
216 struct page *, void *);
217 int generic_write_end(struct file *, struct address_space *,
218 loff_t, unsigned, unsigned,
219 struct page *, void *);
220 void page_zero_new_buffers(struct page *page, unsigned from, unsigned to);
221 int cont_write_begin(struct file *, struct address_space *, loff_t,
222 unsigned, unsigned, struct page **, void **,
223 get_block_t *, loff_t *);
224 int generic_cont_expand_simple(struct inode *inode, loff_t size);
225 int block_commit_write(struct page *page, unsigned from, unsigned to);
226 int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
227 get_block_t get_block);
228 int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
229 get_block_t get_block);
230 /* Convert errno to return value from ->page_mkwrite() call */
231 static inline int block_page_mkwrite_return(int err)
234 return VM_FAULT_LOCKED;
236 return VM_FAULT_NOPAGE;
240 return VM_FAULT_RETRY;
241 /* -ENOSPC, -EDQUOT, -EIO ... */
242 return VM_FAULT_SIGBUS;
244 sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
245 int block_truncate_page(struct address_space *, loff_t, get_block_t *);
246 int nobh_write_begin(struct address_space *, loff_t, unsigned, unsigned,
247 struct page **, void **, get_block_t*);
248 int nobh_write_end(struct file *, struct address_space *,
249 loff_t, unsigned, unsigned,
250 struct page *, void *);
251 int nobh_truncate_page(struct address_space *, loff_t, get_block_t *);
252 int nobh_writepage(struct page *page, get_block_t *get_block,
253 struct writeback_control *wbc);
255 void buffer_init(void);
261 static inline void attach_page_buffers(struct page *page,
262 struct buffer_head *head)
264 page_cache_get(page);
265 SetPagePrivate(page);
266 set_page_private(page, (unsigned long)head);
269 static inline void get_bh(struct buffer_head *bh)
271 atomic_inc(&bh->b_count);
274 static inline void put_bh(struct buffer_head *bh)
276 smp_mb__before_atomic_dec();
277 atomic_dec(&bh->b_count);
280 static inline void brelse(struct buffer_head *bh)
286 static inline void bforget(struct buffer_head *bh)
292 static inline struct buffer_head *
293 sb_bread(struct super_block *sb, sector_t block)
295 return __bread(sb->s_bdev, block, sb->s_blocksize);
299 sb_breadahead(struct super_block *sb, sector_t block)
301 __breadahead(sb->s_bdev, block, sb->s_blocksize);
304 static inline struct buffer_head *
305 sb_getblk(struct super_block *sb, sector_t block)
307 return __getblk(sb->s_bdev, block, sb->s_blocksize);
310 static inline struct buffer_head *
311 sb_find_get_block(struct super_block *sb, sector_t block)
313 return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
317 map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
319 set_buffer_mapped(bh);
320 bh->b_bdev = sb->s_bdev;
321 bh->b_blocknr = block;
322 bh->b_size = sb->s_blocksize;
325 static inline void wait_on_buffer(struct buffer_head *bh)
328 if (buffer_locked(bh))
329 __wait_on_buffer(bh);
332 static inline int trylock_buffer(struct buffer_head *bh)
334 return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));
337 static inline void lock_buffer(struct buffer_head *bh)
340 if (!trylock_buffer(bh))
344 extern int __set_page_dirty_buffers(struct page *page);
346 #else /* CONFIG_BLOCK */
348 static inline void buffer_init(void) {}
349 static inline int try_to_free_buffers(struct page *page) { return 1; }
350 static inline int inode_has_buffers(struct inode *inode) { return 0; }
351 static inline void invalidate_inode_buffers(struct inode *inode) {}
352 static inline int remove_inode_buffers(struct inode *inode) { return 1; }
353 static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
355 #endif /* CONFIG_BLOCK */
356 #endif /* _LINUX_BUFFER_HEAD_H */