[PATCH] change buffer_head.b_size to size_t
[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         BH_Uptodate_Lock,/* Used by the first bh in a page, to serialise
23                           * IO completion of other buffers in the page
24                           */
25
26         BH_Mapped,      /* Has a disk mapping */
27         BH_New,         /* Disk mapping was newly created by get_block */
28         BH_Async_Read,  /* Is under end_buffer_async_read I/O */
29         BH_Async_Write, /* Is under end_buffer_async_write I/O */
30         BH_Delay,       /* Buffer is not yet allocated on disk */
31         BH_Boundary,    /* Block is followed by a discontiguity */
32         BH_Write_EIO,   /* I/O error on write */
33         BH_Ordered,     /* ordered write */
34         BH_Eopnotsupp,  /* operation not supported (barrier) */
35
36         BH_PrivateStart,/* not a state bit, but the first bit available
37                          * for private allocation by other entities
38                          */
39 };
40
41 #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512)
42
43 struct page;
44 struct buffer_head;
45 struct address_space;
46 typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
47
48 /*
49  * Historically, a buffer_head was used to map a single block
50  * within a page, and of course as the unit of I/O through the
51  * filesystem and block layers.  Nowadays the basic I/O unit
52  * is the bio, and buffer_heads are used for extracting block
53  * mappings (via a get_block_t call), for tracking state within
54  * a page (via a page_mapping) and for wrapping bio submission
55  * for backward compatibility reasons (e.g. submit_bh).
56  */
57 struct buffer_head {
58         unsigned long b_state;          /* buffer state bitmap (see above) */
59         struct buffer_head *b_this_page;/* circular list of page's buffers */
60         struct page *b_page;            /* the page this bh is mapped to */
61
62         sector_t b_blocknr;             /* start block number */
63         size_t b_size;                  /* size of mapping */
64         char *b_data;                   /* pointer to data within the page */
65
66         struct block_device *b_bdev;
67         bh_end_io_t *b_end_io;          /* I/O completion */
68         void *b_private;                /* reserved for b_end_io */
69         struct list_head b_assoc_buffers; /* associated with another mapping */
70         atomic_t b_count;               /* users using this buffer_head */
71 };
72
73 /*
74  * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
75  * and buffer_foo() functions.
76  */
77 #define BUFFER_FNS(bit, name)                                           \
78 static inline void set_buffer_##name(struct buffer_head *bh)            \
79 {                                                                       \
80         set_bit(BH_##bit, &(bh)->b_state);                              \
81 }                                                                       \
82 static inline void clear_buffer_##name(struct buffer_head *bh)          \
83 {                                                                       \
84         clear_bit(BH_##bit, &(bh)->b_state);                            \
85 }                                                                       \
86 static inline int buffer_##name(const struct buffer_head *bh)           \
87 {                                                                       \
88         return test_bit(BH_##bit, &(bh)->b_state);                      \
89 }
90
91 /*
92  * test_set_buffer_foo() and test_clear_buffer_foo()
93  */
94 #define TAS_BUFFER_FNS(bit, name)                                       \
95 static inline int test_set_buffer_##name(struct buffer_head *bh)        \
96 {                                                                       \
97         return test_and_set_bit(BH_##bit, &(bh)->b_state);              \
98 }                                                                       \
99 static inline int test_clear_buffer_##name(struct buffer_head *bh)      \
100 {                                                                       \
101         return test_and_clear_bit(BH_##bit, &(bh)->b_state);            \
102 }                                                                       \
103
104 /*
105  * Emit the buffer bitops functions.   Note that there are also functions
106  * of the form "mark_buffer_foo()".  These are higher-level functions which
107  * do something in addition to setting a b_state bit.
108  */
109 BUFFER_FNS(Uptodate, uptodate)
110 BUFFER_FNS(Dirty, dirty)
111 TAS_BUFFER_FNS(Dirty, dirty)
112 BUFFER_FNS(Lock, locked)
113 TAS_BUFFER_FNS(Lock, locked)
114 BUFFER_FNS(Req, req)
115 TAS_BUFFER_FNS(Req, req)
116 BUFFER_FNS(Mapped, mapped)
117 BUFFER_FNS(New, new)
118 BUFFER_FNS(Async_Read, async_read)
119 BUFFER_FNS(Async_Write, async_write)
120 BUFFER_FNS(Delay, delay)
121 BUFFER_FNS(Boundary, boundary)
122 BUFFER_FNS(Write_EIO, write_io_error)
123 BUFFER_FNS(Ordered, ordered)
124 BUFFER_FNS(Eopnotsupp, eopnotsupp)
125
126 #define bh_offset(bh)           ((unsigned long)(bh)->b_data & ~PAGE_MASK)
127 #define touch_buffer(bh)        mark_page_accessed(bh->b_page)
128
129 /* If we *know* page->private refers to buffer_heads */
130 #define page_buffers(page)                                      \
131         ({                                                      \
132                 BUG_ON(!PagePrivate(page));                     \
133                 ((struct buffer_head *)page_private(page));     \
134         })
135 #define page_has_buffers(page)  PagePrivate(page)
136
137 /*
138  * Declarations
139  */
140
141 void FASTCALL(mark_buffer_dirty(struct buffer_head *bh));
142 void init_buffer(struct buffer_head *, bh_end_io_t *, void *);
143 void set_bh_page(struct buffer_head *bh,
144                 struct page *page, unsigned long offset);
145 int try_to_free_buffers(struct page *);
146 struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
147                 int retry);
148 void create_empty_buffers(struct page *, unsigned long,
149                         unsigned long b_state);
150 void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
151 void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
152 void end_buffer_async_write(struct buffer_head *bh, int uptodate);
153
154 /* Things to do with buffers at mapping->private_list */
155 void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
156 int inode_has_buffers(struct inode *);
157 void invalidate_inode_buffers(struct inode *);
158 int remove_inode_buffers(struct inode *inode);
159 int sync_mapping_buffers(struct address_space *mapping);
160 void unmap_underlying_metadata(struct block_device *bdev, sector_t block);
161
162 void mark_buffer_async_write(struct buffer_head *bh);
163 void invalidate_bdev(struct block_device *, int);
164 int sync_blockdev(struct block_device *bdev);
165 void __wait_on_buffer(struct buffer_head *);
166 wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
167 int fsync_bdev(struct block_device *);
168 struct super_block *freeze_bdev(struct block_device *);
169 void thaw_bdev(struct block_device *, struct super_block *);
170 int fsync_super(struct super_block *);
171 int fsync_no_super(struct block_device *);
172 struct buffer_head *__find_get_block(struct block_device *, sector_t, int);
173 struct buffer_head * __getblk(struct block_device *, sector_t, int);
174 void __brelse(struct buffer_head *);
175 void __bforget(struct buffer_head *);
176 void __breadahead(struct block_device *, sector_t block, int size);
177 struct buffer_head *__bread(struct block_device *, sector_t block, int size);
178 struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
179 void free_buffer_head(struct buffer_head * bh);
180 void FASTCALL(unlock_buffer(struct buffer_head *bh));
181 void FASTCALL(__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 submit_bh(int, struct buffer_head *);
185 void write_boundary_block(struct block_device *bdev,
186                         sector_t bblock, unsigned blocksize);
187
188 extern int buffer_heads_over_limit;
189
190 /*
191  * Generic address_space_operations implementations for buffer_head-backed
192  * address_spaces.
193  */
194 int try_to_release_page(struct page * page, gfp_t gfp_mask);
195 void block_invalidatepage(struct page *page, unsigned long offset);
196 void do_invalidatepage(struct page *page, unsigned long offset);
197 int block_write_full_page(struct page *page, get_block_t *get_block,
198                                 struct writeback_control *wbc);
199 int block_read_full_page(struct page*, get_block_t*);
200 int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
201 int cont_prepare_write(struct page*, unsigned, unsigned, get_block_t*,
202                                 loff_t *);
203 int generic_cont_expand(struct inode *inode, loff_t size);
204 int generic_cont_expand_simple(struct inode *inode, loff_t size);
205 int block_commit_write(struct page *page, unsigned from, unsigned to);
206 void block_sync_page(struct page *);
207 sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
208 int generic_commit_write(struct file *, struct page *, unsigned, unsigned);
209 int block_truncate_page(struct address_space *, loff_t, get_block_t *);
210 int file_fsync(struct file *, struct dentry *, int);
211 int nobh_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
212 int nobh_commit_write(struct file *, struct page *, unsigned, unsigned);
213 int nobh_truncate_page(struct address_space *, loff_t);
214 int nobh_writepage(struct page *page, get_block_t *get_block,
215                         struct writeback_control *wbc);
216
217
218 /*
219  * inline definitions
220  */
221
222 static inline void attach_page_buffers(struct page *page,
223                 struct buffer_head *head)
224 {
225         page_cache_get(page);
226         SetPagePrivate(page);
227         set_page_private(page, (unsigned long)head);
228 }
229
230 static inline void get_bh(struct buffer_head *bh)
231 {
232         atomic_inc(&bh->b_count);
233 }
234
235 static inline void put_bh(struct buffer_head *bh)
236 {
237         smp_mb__before_atomic_dec();
238         atomic_dec(&bh->b_count);
239 }
240
241 static inline void brelse(struct buffer_head *bh)
242 {
243         if (bh)
244                 __brelse(bh);
245 }
246
247 static inline void bforget(struct buffer_head *bh)
248 {
249         if (bh)
250                 __bforget(bh);
251 }
252
253 static inline struct buffer_head *
254 sb_bread(struct super_block *sb, sector_t block)
255 {
256         return __bread(sb->s_bdev, block, sb->s_blocksize);
257 }
258
259 static inline void
260 sb_breadahead(struct super_block *sb, sector_t block)
261 {
262         __breadahead(sb->s_bdev, block, sb->s_blocksize);
263 }
264
265 static inline struct buffer_head *
266 sb_getblk(struct super_block *sb, sector_t block)
267 {
268         return __getblk(sb->s_bdev, block, sb->s_blocksize);
269 }
270
271 static inline struct buffer_head *
272 sb_find_get_block(struct super_block *sb, sector_t block)
273 {
274         return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
275 }
276
277 static inline void
278 map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
279 {
280         set_buffer_mapped(bh);
281         bh->b_bdev = sb->s_bdev;
282         bh->b_blocknr = block;
283 }
284
285 /*
286  * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into
287  * __wait_on_buffer() just to trip a debug check.  Because debug code in inline
288  * functions is bloaty.
289  */
290 static inline void wait_on_buffer(struct buffer_head *bh)
291 {
292         might_sleep();
293         if (buffer_locked(bh) || atomic_read(&bh->b_count) == 0)
294                 __wait_on_buffer(bh);
295 }
296
297 static inline void lock_buffer(struct buffer_head *bh)
298 {
299         might_sleep();
300         if (test_set_buffer_locked(bh))
301                 __lock_buffer(bh);
302 }
303
304 #endif /* _LINUX_BUFFER_HEAD_H */