get rid of cont_write_begin_newtrunc
[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_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 */
39
40         BH_PrivateStart,/* not a state bit, but the first bit available
41                          * for private allocation by other entities
42                          */
43 };
44
45 #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512)
46
47 struct page;
48 struct buffer_head;
49 struct address_space;
50 typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
51
52 /*
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).
60  */
61 struct buffer_head {
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 */
65
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 */
69
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
75                                                    associated with */
76         atomic_t b_count;               /* users using this buffer_head */
77 };
78
79 /*
80  * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
81  * and buffer_foo() functions.
82  */
83 #define BUFFER_FNS(bit, name)                                           \
84 static inline void set_buffer_##name(struct buffer_head *bh)            \
85 {                                                                       \
86         set_bit(BH_##bit, &(bh)->b_state);                              \
87 }                                                                       \
88 static inline void clear_buffer_##name(struct buffer_head *bh)          \
89 {                                                                       \
90         clear_bit(BH_##bit, &(bh)->b_state);                            \
91 }                                                                       \
92 static inline int buffer_##name(const struct buffer_head *bh)           \
93 {                                                                       \
94         return test_bit(BH_##bit, &(bh)->b_state);                      \
95 }
96
97 /*
98  * test_set_buffer_foo() and test_clear_buffer_foo()
99  */
100 #define TAS_BUFFER_FNS(bit, name)                                       \
101 static inline int test_set_buffer_##name(struct buffer_head *bh)        \
102 {                                                                       \
103         return test_and_set_bit(BH_##bit, &(bh)->b_state);              \
104 }                                                                       \
105 static inline int test_clear_buffer_##name(struct buffer_head *bh)      \
106 {                                                                       \
107         return test_and_clear_bit(BH_##bit, &(bh)->b_state);            \
108 }                                                                       \
109
110 /*
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.
114  */
115 BUFFER_FNS(Uptodate, uptodate)
116 BUFFER_FNS(Dirty, dirty)
117 TAS_BUFFER_FNS(Dirty, dirty)
118 BUFFER_FNS(Lock, locked)
119 BUFFER_FNS(Req, req)
120 TAS_BUFFER_FNS(Req, req)
121 BUFFER_FNS(Mapped, mapped)
122 BUFFER_FNS(New, new)
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)
131
132 #define bh_offset(bh)           ((unsigned long)(bh)->b_data & ~PAGE_MASK)
133 #define touch_buffer(bh)        mark_page_accessed(bh->b_page)
134
135 /* If we *know* page->private refers to buffer_heads */
136 #define page_buffers(page)                                      \
137         ({                                                      \
138                 BUG_ON(!PagePrivate(page));                     \
139                 ((struct buffer_head *)page_private(page));     \
140         })
141 #define page_has_buffers(page)  PagePrivate(page)
142
143 /*
144  * Declarations
145  */
146
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,
153                 int retry);
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);
159
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);
167
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,
172                         unsigned size);
173 struct buffer_head *__getblk(struct block_device *bdev, sector_t block,
174                         unsigned size);
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 submit_bh(int, struct buffer_head *);
187 void write_boundary_block(struct block_device *bdev,
188                         sector_t bblock, unsigned blocksize);
189 int bh_uptodate_or_lock(struct buffer_head *bh);
190 int bh_submit_read(struct buffer_head *bh);
191
192 extern int buffer_heads_over_limit;
193
194 /*
195  * Generic address_space_operations implementations for buffer_head-backed
196  * address_spaces.
197  */
198 void block_invalidatepage(struct page *page, unsigned long offset);
199 int block_write_full_page(struct page *page, get_block_t *get_block,
200                                 struct writeback_control *wbc);
201 int block_write_full_page_endio(struct page *page, get_block_t *get_block,
202                         struct writeback_control *wbc, bh_end_io_t *handler);
203 int block_read_full_page(struct page*, get_block_t*);
204 int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc,
205                                 unsigned long from);
206 int block_write_begin_newtrunc(struct file *, struct address_space *,
207                                 loff_t, unsigned, unsigned,
208                                 struct page **, void **, get_block_t*);
209 int block_write_begin(struct file *, struct address_space *,
210                                 loff_t, unsigned, unsigned,
211                                 struct page **, void **, get_block_t*);
212 int block_write_end(struct file *, struct address_space *,
213                                 loff_t, unsigned, unsigned,
214                                 struct page *, void *);
215 int generic_write_end(struct file *, struct address_space *,
216                                 loff_t, unsigned, unsigned,
217                                 struct page *, void *);
218 void page_zero_new_buffers(struct page *page, unsigned from, unsigned to);
219 int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
220 int cont_write_begin(struct file *, struct address_space *, loff_t,
221                         unsigned, unsigned, struct page **, void **,
222                         get_block_t *, loff_t *);
223 int generic_cont_expand_simple(struct inode *inode, loff_t size);
224 int block_commit_write(struct page *page, unsigned from, unsigned to);
225 int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
226                                 get_block_t get_block);
227 void block_sync_page(struct page *);
228 sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
229 int block_truncate_page(struct address_space *, loff_t, get_block_t *);
230 int file_fsync(struct file *, int);
231 int nobh_write_begin(struct address_space *, loff_t, unsigned, unsigned,
232                                 struct page **, void **, get_block_t*);
233 int nobh_write_end(struct file *, struct address_space *,
234                                 loff_t, unsigned, unsigned,
235                                 struct page *, void *);
236 int nobh_truncate_page(struct address_space *, loff_t, get_block_t *);
237 int nobh_writepage(struct page *page, get_block_t *get_block,
238                         struct writeback_control *wbc);
239
240 void buffer_init(void);
241
242 /*
243  * inline definitions
244  */
245
246 static inline void attach_page_buffers(struct page *page,
247                 struct buffer_head *head)
248 {
249         page_cache_get(page);
250         SetPagePrivate(page);
251         set_page_private(page, (unsigned long)head);
252 }
253
254 static inline void get_bh(struct buffer_head *bh)
255 {
256         atomic_inc(&bh->b_count);
257 }
258
259 static inline void put_bh(struct buffer_head *bh)
260 {
261         smp_mb__before_atomic_dec();
262         atomic_dec(&bh->b_count);
263 }
264
265 static inline void brelse(struct buffer_head *bh)
266 {
267         if (bh)
268                 __brelse(bh);
269 }
270
271 static inline void bforget(struct buffer_head *bh)
272 {
273         if (bh)
274                 __bforget(bh);
275 }
276
277 static inline struct buffer_head *
278 sb_bread(struct super_block *sb, sector_t block)
279 {
280         return __bread(sb->s_bdev, block, sb->s_blocksize);
281 }
282
283 static inline void
284 sb_breadahead(struct super_block *sb, sector_t block)
285 {
286         __breadahead(sb->s_bdev, block, sb->s_blocksize);
287 }
288
289 static inline struct buffer_head *
290 sb_getblk(struct super_block *sb, sector_t block)
291 {
292         return __getblk(sb->s_bdev, block, sb->s_blocksize);
293 }
294
295 static inline struct buffer_head *
296 sb_find_get_block(struct super_block *sb, sector_t block)
297 {
298         return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
299 }
300
301 static inline void
302 map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
303 {
304         set_buffer_mapped(bh);
305         bh->b_bdev = sb->s_bdev;
306         bh->b_blocknr = block;
307         bh->b_size = sb->s_blocksize;
308 }
309
310 /*
311  * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into
312  * __wait_on_buffer() just to trip a debug check.  Because debug code in inline
313  * functions is bloaty.
314  */
315 static inline void wait_on_buffer(struct buffer_head *bh)
316 {
317         might_sleep();
318         if (buffer_locked(bh) || atomic_read(&bh->b_count) == 0)
319                 __wait_on_buffer(bh);
320 }
321
322 static inline int trylock_buffer(struct buffer_head *bh)
323 {
324         return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));
325 }
326
327 static inline void lock_buffer(struct buffer_head *bh)
328 {
329         might_sleep();
330         if (!trylock_buffer(bh))
331                 __lock_buffer(bh);
332 }
333
334 extern int __set_page_dirty_buffers(struct page *page);
335
336 #else /* CONFIG_BLOCK */
337
338 static inline void buffer_init(void) {}
339 static inline int try_to_free_buffers(struct page *page) { return 1; }
340 static inline int inode_has_buffers(struct inode *inode) { return 0; }
341 static inline void invalidate_inode_buffers(struct inode *inode) {}
342 static inline int remove_inode_buffers(struct inode *inode) { return 1; }
343 static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
344
345 #endif /* CONFIG_BLOCK */
346 #endif /* _LINUX_BUFFER_HEAD_H */