[PATCH] Fix IO error reporting on fsync()
[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
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 TAS_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(Ordered, ordered)
128 BUFFER_FNS(Eopnotsupp, eopnotsupp)
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 FASTCALL(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
157 /* Things to do with buffers at mapping->private_list */
158 void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
159 int inode_has_buffers(struct inode *);
160 void invalidate_inode_buffers(struct inode *);
161 int remove_inode_buffers(struct inode *inode);
162 int sync_mapping_buffers(struct address_space *mapping);
163 void unmap_underlying_metadata(struct block_device *bdev, sector_t block);
164
165 void mark_buffer_async_write(struct buffer_head *bh);
166 void invalidate_bdev(struct block_device *, int);
167 int sync_blockdev(struct block_device *bdev);
168 void __wait_on_buffer(struct buffer_head *);
169 wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
170 int fsync_bdev(struct block_device *);
171 struct super_block *freeze_bdev(struct block_device *);
172 void thaw_bdev(struct block_device *, struct super_block *);
173 int fsync_super(struct super_block *);
174 int fsync_no_super(struct block_device *);
175 struct buffer_head *__find_get_block(struct block_device *, sector_t, int);
176 struct buffer_head * __getblk(struct block_device *, sector_t, int);
177 void __brelse(struct buffer_head *);
178 void __bforget(struct buffer_head *);
179 void __breadahead(struct block_device *, sector_t block, int size);
180 struct buffer_head *__bread(struct block_device *, sector_t block, int size);
181 struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
182 void free_buffer_head(struct buffer_head * bh);
183 void FASTCALL(unlock_buffer(struct buffer_head *bh));
184 void FASTCALL(__lock_buffer(struct buffer_head *bh));
185 void ll_rw_block(int, int, struct buffer_head * bh[]);
186 int sync_dirty_buffer(struct buffer_head *bh);
187 int submit_bh(int, struct buffer_head *);
188 void write_boundary_block(struct block_device *bdev,
189                         sector_t bblock, unsigned blocksize);
190
191 extern int buffer_heads_over_limit;
192
193 /*
194  * Generic address_space_operations implementations for buffer_head-backed
195  * address_spaces.
196  */
197 void block_invalidatepage(struct page *page, unsigned long offset);
198 int block_write_full_page(struct page *page, get_block_t *get_block,
199                                 struct writeback_control *wbc);
200 int block_read_full_page(struct page*, get_block_t*);
201 int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
202 int cont_prepare_write(struct page*, unsigned, unsigned, get_block_t*,
203                                 loff_t *);
204 int generic_cont_expand(struct inode *inode, loff_t size);
205 int generic_cont_expand_simple(struct inode *inode, loff_t size);
206 int block_commit_write(struct page *page, unsigned from, unsigned to);
207 void block_sync_page(struct page *);
208 sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
209 int generic_commit_write(struct file *, struct page *, unsigned, unsigned);
210 int block_truncate_page(struct address_space *, loff_t, get_block_t *);
211 int file_fsync(struct file *, struct dentry *, int);
212 int nobh_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
213 int nobh_commit_write(struct file *, struct page *, unsigned, unsigned);
214 int nobh_truncate_page(struct address_space *, loff_t);
215 int nobh_writepage(struct page *page, get_block_t *get_block,
216                         struct writeback_control *wbc);
217
218 void buffer_init(void);
219
220 /*
221  * inline definitions
222  */
223
224 static inline void attach_page_buffers(struct page *page,
225                 struct buffer_head *head)
226 {
227         page_cache_get(page);
228         SetPagePrivate(page);
229         set_page_private(page, (unsigned long)head);
230 }
231
232 static inline void get_bh(struct buffer_head *bh)
233 {
234         atomic_inc(&bh->b_count);
235 }
236
237 static inline void put_bh(struct buffer_head *bh)
238 {
239         smp_mb__before_atomic_dec();
240         atomic_dec(&bh->b_count);
241 }
242
243 static inline void brelse(struct buffer_head *bh)
244 {
245         if (bh)
246                 __brelse(bh);
247 }
248
249 static inline void bforget(struct buffer_head *bh)
250 {
251         if (bh)
252                 __bforget(bh);
253 }
254
255 static inline struct buffer_head *
256 sb_bread(struct super_block *sb, sector_t block)
257 {
258         return __bread(sb->s_bdev, block, sb->s_blocksize);
259 }
260
261 static inline void
262 sb_breadahead(struct super_block *sb, sector_t block)
263 {
264         __breadahead(sb->s_bdev, block, sb->s_blocksize);
265 }
266
267 static inline struct buffer_head *
268 sb_getblk(struct super_block *sb, sector_t block)
269 {
270         return __getblk(sb->s_bdev, block, sb->s_blocksize);
271 }
272
273 static inline struct buffer_head *
274 sb_find_get_block(struct super_block *sb, sector_t block)
275 {
276         return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
277 }
278
279 static inline void
280 map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
281 {
282         set_buffer_mapped(bh);
283         bh->b_bdev = sb->s_bdev;
284         bh->b_blocknr = block;
285         bh->b_size = sb->s_blocksize;
286 }
287
288 /*
289  * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into
290  * __wait_on_buffer() just to trip a debug check.  Because debug code in inline
291  * functions is bloaty.
292  */
293 static inline void wait_on_buffer(struct buffer_head *bh)
294 {
295         might_sleep();
296         if (buffer_locked(bh) || atomic_read(&bh->b_count) == 0)
297                 __wait_on_buffer(bh);
298 }
299
300 static inline void lock_buffer(struct buffer_head *bh)
301 {
302         might_sleep();
303         if (test_set_buffer_locked(bh))
304                 __lock_buffer(bh);
305 }
306
307 extern int __set_page_dirty_buffers(struct page *page);
308
309 #else /* CONFIG_BLOCK */
310
311 static inline void buffer_init(void) {}
312 static inline int try_to_free_buffers(struct page *page) { return 1; }
313 static inline int sync_blockdev(struct block_device *bdev) { return 0; }
314 static inline int inode_has_buffers(struct inode *inode) { return 0; }
315 static inline void invalidate_inode_buffers(struct inode *inode) {}
316 static inline int remove_inode_buffers(struct inode *inode) { return 1; }
317 static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
318 static inline void invalidate_bdev(struct block_device *bdev, int destroy_dirty_buffers) {}
319
320
321 #endif /* CONFIG_BLOCK */
322 #endif /* _LINUX_BUFFER_HEAD_H */