Linux-2.6.12-rc2
[linux-2.6.git] / include / linux / buffer_head.h
1 /*
2  * include/linux/buffer_head.h
3  *
4  * Everything to do with buffer_heads.
5  */
6
7 #ifndef _LINUX_BUFFER_HEAD_H
8 #define _LINUX_BUFFER_HEAD_H
9
10 #include <linux/types.h>
11 #include <linux/fs.h>
12 #include <linux/linkage.h>
13 #include <linux/pagemap.h>
14 #include <linux/wait.h>
15 #include <asm/atomic.h>
16
17 enum bh_state_bits {
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
23         BH_Mapped,      /* Has a disk mapping */
24         BH_New,         /* Disk mapping was newly created by get_block */
25         BH_Async_Read,  /* Is under end_buffer_async_read I/O */
26         BH_Async_Write, /* Is under end_buffer_async_write I/O */
27         BH_Delay,       /* Buffer is not yet allocated on disk */
28         BH_Boundary,    /* Block is followed by a discontiguity */
29         BH_Write_EIO,   /* I/O error on write */
30         BH_Ordered,     /* ordered write */
31         BH_Eopnotsupp,  /* operation not supported (barrier) */
32
33         BH_PrivateStart,/* not a state bit, but the first bit available
34                          * for private allocation by other entities
35                          */
36 };
37
38 #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512)
39
40 struct page;
41 struct buffer_head;
42 struct address_space;
43 typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
44
45 /*
46  * Keep related fields in common cachelines.  The most commonly accessed
47  * field (b_state) goes at the start so the compiler does not generate
48  * indexed addressing for it.
49  */
50 struct buffer_head {
51         /* First cache line: */
52         unsigned long b_state;          /* buffer state bitmap (see above) */
53         struct buffer_head *b_this_page;/* circular list of page's buffers */
54         struct page *b_page;            /* the page this bh is mapped to */
55         atomic_t b_count;               /* users using this block */
56         u32 b_size;                     /* block size */
57
58         sector_t b_blocknr;             /* block number */
59         char *b_data;                   /* pointer to data block */
60
61         struct block_device *b_bdev;
62         bh_end_io_t *b_end_io;          /* I/O completion */
63         void *b_private;                /* reserved for b_end_io */
64         struct list_head b_assoc_buffers; /* associated with another mapping */
65 };
66
67 /*
68  * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
69  * and buffer_foo() functions.
70  */
71 #define BUFFER_FNS(bit, name)                                           \
72 static inline void set_buffer_##name(struct buffer_head *bh)            \
73 {                                                                       \
74         set_bit(BH_##bit, &(bh)->b_state);                              \
75 }                                                                       \
76 static inline void clear_buffer_##name(struct buffer_head *bh)          \
77 {                                                                       \
78         clear_bit(BH_##bit, &(bh)->b_state);                            \
79 }                                                                       \
80 static inline int buffer_##name(const struct buffer_head *bh)           \
81 {                                                                       \
82         return test_bit(BH_##bit, &(bh)->b_state);                      \
83 }
84
85 /*
86  * test_set_buffer_foo() and test_clear_buffer_foo()
87  */
88 #define TAS_BUFFER_FNS(bit, name)                                       \
89 static inline int test_set_buffer_##name(struct buffer_head *bh)        \
90 {                                                                       \
91         return test_and_set_bit(BH_##bit, &(bh)->b_state);              \
92 }                                                                       \
93 static inline int test_clear_buffer_##name(struct buffer_head *bh)      \
94 {                                                                       \
95         return test_and_clear_bit(BH_##bit, &(bh)->b_state);            \
96 }                                                                       \
97
98 /*
99  * Emit the buffer bitops functions.   Note that there are also functions
100  * of the form "mark_buffer_foo()".  These are higher-level functions which
101  * do something in addition to setting a b_state bit.
102  */
103 BUFFER_FNS(Uptodate, uptodate)
104 BUFFER_FNS(Dirty, dirty)
105 TAS_BUFFER_FNS(Dirty, dirty)
106 BUFFER_FNS(Lock, locked)
107 TAS_BUFFER_FNS(Lock, locked)
108 BUFFER_FNS(Req, req)
109 TAS_BUFFER_FNS(Req, req)
110 BUFFER_FNS(Mapped, mapped)
111 BUFFER_FNS(New, new)
112 BUFFER_FNS(Async_Read, async_read)
113 BUFFER_FNS(Async_Write, async_write)
114 BUFFER_FNS(Delay, delay)
115 BUFFER_FNS(Boundary, boundary)
116 BUFFER_FNS(Write_EIO, write_io_error)
117 BUFFER_FNS(Ordered, ordered)
118 BUFFER_FNS(Eopnotsupp, eopnotsupp)
119
120 #define bh_offset(bh)           ((unsigned long)(bh)->b_data & ~PAGE_MASK)
121 #define touch_buffer(bh)        mark_page_accessed(bh->b_page)
122
123 /* If we *know* page->private refers to buffer_heads */
124 #define page_buffers(page)                                      \
125         ({                                                      \
126                 BUG_ON(!PagePrivate(page));             \
127                 ((struct buffer_head *)(page)->private);        \
128         })
129 #define page_has_buffers(page)  PagePrivate(page)
130
131 /*
132  * Declarations
133  */
134
135 void FASTCALL(mark_buffer_dirty(struct buffer_head *bh));
136 void init_buffer(struct buffer_head *, bh_end_io_t *, void *);
137 void set_bh_page(struct buffer_head *bh,
138                 struct page *page, unsigned long offset);
139 int try_to_free_buffers(struct page *);
140 struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
141                 int retry);
142 void create_empty_buffers(struct page *, unsigned long,
143                         unsigned long b_state);
144 void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
145 void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
146 void end_buffer_async_write(struct buffer_head *bh, int uptodate);
147
148 /* Things to do with buffers at mapping->private_list */
149 void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
150 int inode_has_buffers(struct inode *);
151 void invalidate_inode_buffers(struct inode *);
152 int remove_inode_buffers(struct inode *inode);
153 int sync_mapping_buffers(struct address_space *mapping);
154 void unmap_underlying_metadata(struct block_device *bdev, sector_t block);
155
156 void mark_buffer_async_write(struct buffer_head *bh);
157 void invalidate_bdev(struct block_device *, int);
158 int sync_blockdev(struct block_device *bdev);
159 void __wait_on_buffer(struct buffer_head *);
160 wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
161 int fsync_bdev(struct block_device *);
162 struct super_block *freeze_bdev(struct block_device *);
163 void thaw_bdev(struct block_device *, struct super_block *);
164 int fsync_super(struct super_block *);
165 int fsync_no_super(struct block_device *);
166 struct buffer_head *__find_get_block(struct block_device *, sector_t, int);
167 struct buffer_head * __getblk(struct block_device *, sector_t, int);
168 void __brelse(struct buffer_head *);
169 void __bforget(struct buffer_head *);
170 void __breadahead(struct block_device *, sector_t block, int size);
171 struct buffer_head *__bread(struct block_device *, sector_t block, int size);
172 struct buffer_head *alloc_buffer_head(unsigned int __nocast gfp_flags);
173 void free_buffer_head(struct buffer_head * bh);
174 void FASTCALL(unlock_buffer(struct buffer_head *bh));
175 void FASTCALL(__lock_buffer(struct buffer_head *bh));
176 void ll_rw_block(int, int, struct buffer_head * bh[]);
177 int sync_dirty_buffer(struct buffer_head *bh);
178 int submit_bh(int, struct buffer_head *);
179 void write_boundary_block(struct block_device *bdev,
180                         sector_t bblock, unsigned blocksize);
181
182 extern int buffer_heads_over_limit;
183
184 /*
185  * Generic address_space_operations implementations for buffer_head-backed
186  * address_spaces.
187  */
188 int try_to_release_page(struct page * page, int gfp_mask);
189 int block_invalidatepage(struct page *page, unsigned long offset);
190 int block_write_full_page(struct page *page, get_block_t *get_block,
191                                 struct writeback_control *wbc);
192 int block_read_full_page(struct page*, get_block_t*);
193 int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
194 int cont_prepare_write(struct page*, unsigned, unsigned, get_block_t*,
195                                 loff_t *);
196 int generic_cont_expand(struct inode *inode, loff_t size) ;
197 int block_commit_write(struct page *page, unsigned from, unsigned to);
198 int block_sync_page(struct page *);
199 sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
200 int generic_commit_write(struct file *, struct page *, unsigned, unsigned);
201 int block_truncate_page(struct address_space *, loff_t, get_block_t *);
202 int file_fsync(struct file *, struct dentry *, int);
203 int nobh_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
204 int nobh_commit_write(struct file *, struct page *, unsigned, unsigned);
205 int nobh_truncate_page(struct address_space *, loff_t);
206 int nobh_writepage(struct page *page, get_block_t *get_block,
207                         struct writeback_control *wbc);
208
209
210 /*
211  * inline definitions
212  */
213
214 static inline void attach_page_buffers(struct page *page,
215                 struct buffer_head *head)
216 {
217         page_cache_get(page);
218         SetPagePrivate(page);
219         page->private = (unsigned long)head;
220 }
221
222 static inline void get_bh(struct buffer_head *bh)
223 {
224         atomic_inc(&bh->b_count);
225 }
226
227 static inline void put_bh(struct buffer_head *bh)
228 {
229         smp_mb__before_atomic_dec();
230         atomic_dec(&bh->b_count);
231 }
232
233 static inline void brelse(struct buffer_head *bh)
234 {
235         if (bh)
236                 __brelse(bh);
237 }
238
239 static inline void bforget(struct buffer_head *bh)
240 {
241         if (bh)
242                 __bforget(bh);
243 }
244
245 static inline struct buffer_head *
246 sb_bread(struct super_block *sb, sector_t block)
247 {
248         return __bread(sb->s_bdev, block, sb->s_blocksize);
249 }
250
251 static inline void
252 sb_breadahead(struct super_block *sb, sector_t block)
253 {
254         __breadahead(sb->s_bdev, block, sb->s_blocksize);
255 }
256
257 static inline struct buffer_head *
258 sb_getblk(struct super_block *sb, sector_t block)
259 {
260         return __getblk(sb->s_bdev, block, sb->s_blocksize);
261 }
262
263 static inline struct buffer_head *
264 sb_find_get_block(struct super_block *sb, sector_t block)
265 {
266         return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
267 }
268
269 static inline void
270 map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
271 {
272         set_buffer_mapped(bh);
273         bh->b_bdev = sb->s_bdev;
274         bh->b_blocknr = block;
275 }
276
277 /*
278  * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into
279  * __wait_on_buffer() just to trip a debug check.  Because debug code in inline
280  * functions is bloaty.
281  */
282 static inline void wait_on_buffer(struct buffer_head *bh)
283 {
284         might_sleep();
285         if (buffer_locked(bh) || atomic_read(&bh->b_count) == 0)
286                 __wait_on_buffer(bh);
287 }
288
289 static inline void lock_buffer(struct buffer_head *bh)
290 {
291         might_sleep();
292         if (test_set_buffer_locked(bh))
293                 __lock_buffer(bh);
294 }
295
296 #endif /* _LINUX_BUFFER_HEAD_H */