Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394...
[pandora-kernel.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_Eopnotsupp,  /* operation not supported (barrier) */
36         BH_Unwritten,   /* Buffer is allocated on disk but not written */
37         BH_Quiet,       /* Buffer Error Prinks to be quiet */
38
39         BH_PrivateStart,/* not a state bit, but the first bit available
40                          * for private allocation by other entities
41                          */
42 };
43
44 #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512)
45
46 struct page;
47 struct buffer_head;
48 struct address_space;
49 typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
50
51 /*
52  * Historically, a buffer_head was used to map a single block
53  * within a page, and of course as the unit of I/O through the
54  * filesystem and block layers.  Nowadays the basic I/O unit
55  * is the bio, and buffer_heads are used for extracting block
56  * mappings (via a get_block_t call), for tracking state within
57  * a page (via a page_mapping) and for wrapping bio submission
58  * for backward compatibility reasons (e.g. submit_bh).
59  */
60 struct buffer_head {
61         unsigned long b_state;          /* buffer state bitmap (see above) */
62         struct buffer_head *b_this_page;/* circular list of page's buffers */
63         struct page *b_page;            /* the page this bh is mapped to */
64
65         sector_t b_blocknr;             /* start block number */
66         size_t b_size;                  /* size of mapping */
67         char *b_data;                   /* pointer to data within the page */
68
69         struct block_device *b_bdev;
70         bh_end_io_t *b_end_io;          /* I/O completion */
71         void *b_private;                /* reserved for b_end_io */
72         struct list_head b_assoc_buffers; /* associated with another mapping */
73         struct address_space *b_assoc_map;      /* mapping this buffer is
74                                                    associated with */
75         atomic_t b_count;               /* users using this buffer_head */
76 };
77
78 /*
79  * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
80  * and buffer_foo() functions.
81  */
82 #define BUFFER_FNS(bit, name)                                           \
83 static inline void set_buffer_##name(struct buffer_head *bh)            \
84 {                                                                       \
85         set_bit(BH_##bit, &(bh)->b_state);                              \
86 }                                                                       \
87 static inline void clear_buffer_##name(struct buffer_head *bh)          \
88 {                                                                       \
89         clear_bit(BH_##bit, &(bh)->b_state);                            \
90 }                                                                       \
91 static inline int buffer_##name(const struct buffer_head *bh)           \
92 {                                                                       \
93         return test_bit(BH_##bit, &(bh)->b_state);                      \
94 }
95
96 /*
97  * test_set_buffer_foo() and test_clear_buffer_foo()
98  */
99 #define TAS_BUFFER_FNS(bit, name)                                       \
100 static inline int test_set_buffer_##name(struct buffer_head *bh)        \
101 {                                                                       \
102         return test_and_set_bit(BH_##bit, &(bh)->b_state);              \
103 }                                                                       \
104 static inline int test_clear_buffer_##name(struct buffer_head *bh)      \
105 {                                                                       \
106         return test_and_clear_bit(BH_##bit, &(bh)->b_state);            \
107 }                                                                       \
108
109 /*
110  * Emit the buffer bitops functions.   Note that there are also functions
111  * of the form "mark_buffer_foo()".  These are higher-level functions which
112  * do something in addition to setting a b_state bit.
113  */
114 BUFFER_FNS(Uptodate, uptodate)
115 BUFFER_FNS(Dirty, dirty)
116 TAS_BUFFER_FNS(Dirty, dirty)
117 BUFFER_FNS(Lock, locked)
118 BUFFER_FNS(Req, req)
119 TAS_BUFFER_FNS(Req, req)
120 BUFFER_FNS(Mapped, mapped)
121 BUFFER_FNS(New, new)
122 BUFFER_FNS(Async_Read, async_read)
123 BUFFER_FNS(Async_Write, async_write)
124 BUFFER_FNS(Delay, delay)
125 BUFFER_FNS(Boundary, boundary)
126 BUFFER_FNS(Write_EIO, write_io_error)
127 BUFFER_FNS(Eopnotsupp, eopnotsupp)
128 BUFFER_FNS(Unwritten, unwritten)
129
130 #define bh_offset(bh)           ((unsigned long)(bh)->b_data & ~PAGE_MASK)
131 #define touch_buffer(bh)        mark_page_accessed(bh->b_page)
132
133 /* If we *know* page->private refers to buffer_heads */
134 #define page_buffers(page)                                      \
135         ({                                                      \
136                 BUG_ON(!PagePrivate(page));                     \
137                 ((struct buffer_head *)page_private(page));     \
138         })
139 #define page_has_buffers(page)  PagePrivate(page)
140
141 /*
142  * Declarations
143  */
144
145 void mark_buffer_dirty(struct buffer_head *bh);
146 void init_buffer(struct buffer_head *, bh_end_io_t *, void *);
147 void set_bh_page(struct buffer_head *bh,
148                 struct page *page, unsigned long offset);
149 int try_to_free_buffers(struct page *);
150 struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
151                 int retry);
152 void create_empty_buffers(struct page *, unsigned long,
153                         unsigned long b_state);
154 void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
155 void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
156 void end_buffer_async_write(struct buffer_head *bh, int uptodate);
157
158 /* Things to do with buffers at mapping->private_list */
159 void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
160 int inode_has_buffers(struct inode *);
161 void invalidate_inode_buffers(struct inode *);
162 int remove_inode_buffers(struct inode *inode);
163 int sync_mapping_buffers(struct address_space *mapping);
164 void unmap_underlying_metadata(struct block_device *bdev, sector_t block);
165
166 void mark_buffer_async_write(struct buffer_head *bh);
167 void __wait_on_buffer(struct buffer_head *);
168 wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
169 struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block,
170                         unsigned size);
171 struct buffer_head *__getblk(struct block_device *bdev, sector_t block,
172                         unsigned size);
173 void __brelse(struct buffer_head *);
174 void __bforget(struct buffer_head *);
175 void __breadahead(struct block_device *, sector_t block, unsigned int size);
176 struct buffer_head *__bread(struct block_device *, sector_t block, unsigned size);
177 void invalidate_bh_lrus(void);
178 struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
179 void free_buffer_head(struct buffer_head * bh);
180 void unlock_buffer(struct buffer_head *bh);
181 void __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 __sync_dirty_buffer(struct buffer_head *bh, int rw);
185 void write_dirty_buffer(struct buffer_head *bh, int rw);
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(struct address_space *mapping, loff_t pos, unsigned len,
207                 unsigned flags, struct page **pagep, get_block_t *get_block);
208 int __block_write_begin(struct page *page, loff_t pos, unsigned len,
209                 get_block_t *get_block);
210 int block_write_end(struct file *, struct address_space *,
211                                 loff_t, unsigned, unsigned,
212                                 struct page *, void *);
213 int generic_write_end(struct file *, struct address_space *,
214                                 loff_t, unsigned, unsigned,
215                                 struct page *, void *);
216 void page_zero_new_buffers(struct page *page, unsigned from, unsigned to);
217 int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
218 int cont_write_begin(struct file *, struct address_space *, loff_t,
219                         unsigned, unsigned, struct page **, void **,
220                         get_block_t *, loff_t *);
221 int generic_cont_expand_simple(struct inode *inode, loff_t size);
222 int block_commit_write(struct page *page, unsigned from, unsigned to);
223 int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
224                                 get_block_t get_block);
225 void block_sync_page(struct page *);
226 sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
227 int block_truncate_page(struct address_space *, loff_t, get_block_t *);
228 int nobh_write_begin(struct address_space *, loff_t, unsigned, unsigned,
229                                 struct page **, void **, get_block_t*);
230 int nobh_write_end(struct file *, struct address_space *,
231                                 loff_t, unsigned, unsigned,
232                                 struct page *, void *);
233 int nobh_truncate_page(struct address_space *, loff_t, get_block_t *);
234 int nobh_writepage(struct page *page, get_block_t *get_block,
235                         struct writeback_control *wbc);
236
237 void buffer_init(void);
238
239 /*
240  * inline definitions
241  */
242
243 static inline void attach_page_buffers(struct page *page,
244                 struct buffer_head *head)
245 {
246         page_cache_get(page);
247         SetPagePrivate(page);
248         set_page_private(page, (unsigned long)head);
249 }
250
251 static inline void get_bh(struct buffer_head *bh)
252 {
253         atomic_inc(&bh->b_count);
254 }
255
256 static inline void put_bh(struct buffer_head *bh)
257 {
258         smp_mb__before_atomic_dec();
259         atomic_dec(&bh->b_count);
260 }
261
262 static inline void brelse(struct buffer_head *bh)
263 {
264         if (bh)
265                 __brelse(bh);
266 }
267
268 static inline void bforget(struct buffer_head *bh)
269 {
270         if (bh)
271                 __bforget(bh);
272 }
273
274 static inline struct buffer_head *
275 sb_bread(struct super_block *sb, sector_t block)
276 {
277         return __bread(sb->s_bdev, block, sb->s_blocksize);
278 }
279
280 static inline void
281 sb_breadahead(struct super_block *sb, sector_t block)
282 {
283         __breadahead(sb->s_bdev, block, sb->s_blocksize);
284 }
285
286 static inline struct buffer_head *
287 sb_getblk(struct super_block *sb, sector_t block)
288 {
289         return __getblk(sb->s_bdev, block, sb->s_blocksize);
290 }
291
292 static inline struct buffer_head *
293 sb_find_get_block(struct super_block *sb, sector_t block)
294 {
295         return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
296 }
297
298 static inline void
299 map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
300 {
301         set_buffer_mapped(bh);
302         bh->b_bdev = sb->s_bdev;
303         bh->b_blocknr = block;
304         bh->b_size = sb->s_blocksize;
305 }
306
307 static inline void wait_on_buffer(struct buffer_head *bh)
308 {
309         might_sleep();
310         if (buffer_locked(bh))
311                 __wait_on_buffer(bh);
312 }
313
314 static inline int trylock_buffer(struct buffer_head *bh)
315 {
316         return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));
317 }
318
319 static inline void lock_buffer(struct buffer_head *bh)
320 {
321         might_sleep();
322         if (!trylock_buffer(bh))
323                 __lock_buffer(bh);
324 }
325
326 extern int __set_page_dirty_buffers(struct page *page);
327
328 #else /* CONFIG_BLOCK */
329
330 static inline void buffer_init(void) {}
331 static inline int try_to_free_buffers(struct page *page) { return 1; }
332 static inline int inode_has_buffers(struct inode *inode) { return 0; }
333 static inline void invalidate_inode_buffers(struct inode *inode) {}
334 static inline int remove_inode_buffers(struct inode *inode) { return 1; }
335 static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
336
337 #endif /* CONFIG_BLOCK */
338 #endif /* _LINUX_BUFFER_HEAD_H */