fs: kill block_prepare_write
[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 #ifdef CONFIG_BLOCK
18
19 enum bh_state_bits {
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
26                           */
27
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
38         BH_PrivateStart,/* not a state bit, but the first bit available
39                          * for private allocation by other entities
40                          */
41 };
42
43 #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512)
44
45 struct page;
46 struct buffer_head;
47 struct address_space;
48 typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
49
50 /*
51  * Historically, a buffer_head was used to map a single block
52  * within a page, and of course as the unit of I/O through the
53  * filesystem and block layers.  Nowadays the basic I/O unit
54  * is the bio, and buffer_heads are used for extracting block
55  * mappings (via a get_block_t call), for tracking state within
56  * a page (via a page_mapping) and for wrapping bio submission
57  * for backward compatibility reasons (e.g. submit_bh).
58  */
59 struct buffer_head {
60         unsigned long b_state;          /* buffer state bitmap (see above) */
61         struct buffer_head *b_this_page;/* circular list of page's buffers */
62         struct page *b_page;            /* the page this bh is mapped to */
63
64         sector_t b_blocknr;             /* start block number */
65         size_t b_size;                  /* size of mapping */
66         char *b_data;                   /* pointer to data within the page */
67
68         struct block_device *b_bdev;
69         bh_end_io_t *b_end_io;          /* I/O completion */
70         void *b_private;                /* reserved for b_end_io */
71         struct list_head b_assoc_buffers; /* associated with another mapping */
72         struct address_space *b_assoc_map;      /* mapping this buffer is
73                                                    associated with */
74         atomic_t b_count;               /* users using this buffer_head */
75 };
76
77 /*
78  * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
79  * and buffer_foo() functions.
80  */
81 #define BUFFER_FNS(bit, name)                                           \
82 static inline void set_buffer_##name(struct buffer_head *bh)            \
83 {                                                                       \
84         set_bit(BH_##bit, &(bh)->b_state);                              \
85 }                                                                       \
86 static inline void clear_buffer_##name(struct buffer_head *bh)          \
87 {                                                                       \
88         clear_bit(BH_##bit, &(bh)->b_state);                            \
89 }                                                                       \
90 static inline int buffer_##name(const struct buffer_head *bh)           \
91 {                                                                       \
92         return test_bit(BH_##bit, &(bh)->b_state);                      \
93 }
94
95 /*
96  * test_set_buffer_foo() and test_clear_buffer_foo()
97  */
98 #define TAS_BUFFER_FNS(bit, name)                                       \
99 static inline int test_set_buffer_##name(struct buffer_head *bh)        \
100 {                                                                       \
101         return test_and_set_bit(BH_##bit, &(bh)->b_state);              \
102 }                                                                       \
103 static inline int test_clear_buffer_##name(struct buffer_head *bh)      \
104 {                                                                       \
105         return test_and_clear_bit(BH_##bit, &(bh)->b_state);            \
106 }                                                                       \
107
108 /*
109  * Emit the buffer bitops functions.   Note that there are also functions
110  * of the form "mark_buffer_foo()".  These are higher-level functions which
111  * do something in addition to setting a b_state bit.
112  */
113 BUFFER_FNS(Uptodate, uptodate)
114 BUFFER_FNS(Dirty, dirty)
115 TAS_BUFFER_FNS(Dirty, dirty)
116 BUFFER_FNS(Lock, locked)
117 BUFFER_FNS(Req, req)
118 TAS_BUFFER_FNS(Req, req)
119 BUFFER_FNS(Mapped, mapped)
120 BUFFER_FNS(New, new)
121 BUFFER_FNS(Async_Read, async_read)
122 BUFFER_FNS(Async_Write, async_write)
123 BUFFER_FNS(Delay, delay)
124 BUFFER_FNS(Boundary, boundary)
125 BUFFER_FNS(Write_EIO, write_io_error)
126 BUFFER_FNS(Unwritten, unwritten)
127
128 #define bh_offset(bh)           ((unsigned long)(bh)->b_data & ~PAGE_MASK)
129 #define touch_buffer(bh)        mark_page_accessed(bh->b_page)
130
131 /* If we *know* page->private refers to buffer_heads */
132 #define page_buffers(page)                                      \
133         ({                                                      \
134                 BUG_ON(!PagePrivate(page));                     \
135                 ((struct buffer_head *)page_private(page));     \
136         })
137 #define page_has_buffers(page)  PagePrivate(page)
138
139 /*
140  * Declarations
141  */
142
143 void mark_buffer_dirty(struct buffer_head *bh);
144 void init_buffer(struct buffer_head *, bh_end_io_t *, void *);
145 void set_bh_page(struct buffer_head *bh,
146                 struct page *page, unsigned long offset);
147 int try_to_free_buffers(struct page *);
148 struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
149                 int retry);
150 void create_empty_buffers(struct page *, unsigned long,
151                         unsigned long b_state);
152 void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
153 void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
154 void end_buffer_async_write(struct buffer_head *bh, int uptodate);
155
156 /* Things to do with buffers at mapping->private_list */
157 void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
158 int inode_has_buffers(struct inode *);
159 void invalidate_inode_buffers(struct inode *);
160 int remove_inode_buffers(struct inode *inode);
161 int sync_mapping_buffers(struct address_space *mapping);
162 void unmap_underlying_metadata(struct block_device *bdev, sector_t block);
163
164 void mark_buffer_async_write(struct buffer_head *bh);
165 void __wait_on_buffer(struct buffer_head *);
166 wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
167 struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block,
168                         unsigned size);
169 struct buffer_head *__getblk(struct block_device *bdev, sector_t block,
170                         unsigned size);
171 void __brelse(struct buffer_head *);
172 void __bforget(struct buffer_head *);
173 void __breadahead(struct block_device *, sector_t block, unsigned int size);
174 struct buffer_head *__bread(struct block_device *, sector_t block, unsigned size);
175 void invalidate_bh_lrus(void);
176 struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
177 void free_buffer_head(struct buffer_head * bh);
178 void unlock_buffer(struct buffer_head *bh);
179 void __lock_buffer(struct buffer_head *bh);
180 void ll_rw_block(int, int, struct buffer_head * bh[]);
181 int sync_dirty_buffer(struct buffer_head *bh);
182 int __sync_dirty_buffer(struct buffer_head *bh, int rw);
183 void write_dirty_buffer(struct buffer_head *bh, int rw);
184 int submit_bh(int, struct buffer_head *);
185 void write_boundary_block(struct block_device *bdev,
186                         sector_t bblock, unsigned blocksize);
187 int bh_uptodate_or_lock(struct buffer_head *bh);
188 int bh_submit_read(struct buffer_head *bh);
189
190 extern int buffer_heads_over_limit;
191
192 /*
193  * Generic address_space_operations implementations for buffer_head-backed
194  * address_spaces.
195  */
196 void block_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_write_full_page_endio(struct page *page, get_block_t *get_block,
200                         struct writeback_control *wbc, bh_end_io_t *handler);
201 int block_read_full_page(struct page*, get_block_t*);
202 int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc,
203                                 unsigned long from);
204 int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
205                 unsigned flags, struct page **pagep, get_block_t *get_block);
206 int __block_write_begin(struct page *page, loff_t pos, unsigned len,
207                 get_block_t *get_block);
208 int block_write_end(struct file *, struct address_space *,
209                                 loff_t, unsigned, unsigned,
210                                 struct page *, void *);
211 int generic_write_end(struct file *, struct address_space *,
212                                 loff_t, unsigned, unsigned,
213                                 struct page *, void *);
214 void page_zero_new_buffers(struct page *page, unsigned from, unsigned to);
215 int cont_write_begin(struct file *, struct address_space *, loff_t,
216                         unsigned, unsigned, struct page **, void **,
217                         get_block_t *, loff_t *);
218 int generic_cont_expand_simple(struct inode *inode, loff_t size);
219 int block_commit_write(struct page *page, unsigned from, unsigned to);
220 int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
221                                 get_block_t get_block);
222 void block_sync_page(struct page *);
223 sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
224 int block_truncate_page(struct address_space *, loff_t, get_block_t *);
225 int nobh_write_begin(struct address_space *, loff_t, unsigned, unsigned,
226                                 struct page **, void **, get_block_t*);
227 int nobh_write_end(struct file *, struct address_space *,
228                                 loff_t, unsigned, unsigned,
229                                 struct page *, void *);
230 int nobh_truncate_page(struct address_space *, loff_t, get_block_t *);
231 int nobh_writepage(struct page *page, get_block_t *get_block,
232                         struct writeback_control *wbc);
233
234 void buffer_init(void);
235
236 /*
237  * inline definitions
238  */
239
240 static inline void attach_page_buffers(struct page *page,
241                 struct buffer_head *head)
242 {
243         page_cache_get(page);
244         SetPagePrivate(page);
245         set_page_private(page, (unsigned long)head);
246 }
247
248 static inline void get_bh(struct buffer_head *bh)
249 {
250         atomic_inc(&bh->b_count);
251 }
252
253 static inline void put_bh(struct buffer_head *bh)
254 {
255         smp_mb__before_atomic_dec();
256         atomic_dec(&bh->b_count);
257 }
258
259 static inline void brelse(struct buffer_head *bh)
260 {
261         if (bh)
262                 __brelse(bh);
263 }
264
265 static inline void bforget(struct buffer_head *bh)
266 {
267         if (bh)
268                 __bforget(bh);
269 }
270
271 static inline struct buffer_head *
272 sb_bread(struct super_block *sb, sector_t block)
273 {
274         return __bread(sb->s_bdev, block, sb->s_blocksize);
275 }
276
277 static inline void
278 sb_breadahead(struct super_block *sb, sector_t block)
279 {
280         __breadahead(sb->s_bdev, block, sb->s_blocksize);
281 }
282
283 static inline struct buffer_head *
284 sb_getblk(struct super_block *sb, sector_t block)
285 {
286         return __getblk(sb->s_bdev, block, sb->s_blocksize);
287 }
288
289 static inline struct buffer_head *
290 sb_find_get_block(struct super_block *sb, sector_t block)
291 {
292         return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
293 }
294
295 static inline void
296 map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
297 {
298         set_buffer_mapped(bh);
299         bh->b_bdev = sb->s_bdev;
300         bh->b_blocknr = block;
301         bh->b_size = sb->s_blocksize;
302 }
303
304 static inline void wait_on_buffer(struct buffer_head *bh)
305 {
306         might_sleep();
307         if (buffer_locked(bh))
308                 __wait_on_buffer(bh);
309 }
310
311 static inline int trylock_buffer(struct buffer_head *bh)
312 {
313         return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));
314 }
315
316 static inline void lock_buffer(struct buffer_head *bh)
317 {
318         might_sleep();
319         if (!trylock_buffer(bh))
320                 __lock_buffer(bh);
321 }
322
323 extern int __set_page_dirty_buffers(struct page *page);
324
325 #else /* CONFIG_BLOCK */
326
327 static inline void buffer_init(void) {}
328 static inline int try_to_free_buffers(struct page *page) { return 1; }
329 static inline int inode_has_buffers(struct inode *inode) { return 0; }
330 static inline void invalidate_inode_buffers(struct inode *inode) {}
331 static inline int remove_inode_buffers(struct inode *inode) { return 1; }
332 static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
333
334 #endif /* CONFIG_BLOCK */
335 #endif /* _LINUX_BUFFER_HEAD_H */