[PATCH] Make BH_Unwritten a first class bufferhead flag V2
[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
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 TAS_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 FASTCALL(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
159 /* Things to do with buffers at mapping->private_list */
160 void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
161 int inode_has_buffers(struct inode *);
162 void invalidate_inode_buffers(struct inode *);
163 int remove_inode_buffers(struct inode *inode);
164 int sync_mapping_buffers(struct address_space *mapping);
165 void unmap_underlying_metadata(struct block_device *bdev, sector_t block);
166
167 void mark_buffer_async_write(struct buffer_head *bh);
168 void invalidate_bdev(struct block_device *, int);
169 int sync_blockdev(struct block_device *bdev);
170 void __wait_on_buffer(struct buffer_head *);
171 wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
172 int fsync_bdev(struct block_device *);
173 struct super_block *freeze_bdev(struct block_device *);
174 void thaw_bdev(struct block_device *, struct super_block *);
175 int fsync_super(struct super_block *);
176 int fsync_no_super(struct block_device *);
177 struct buffer_head *__find_get_block(struct block_device *, sector_t, int);
178 struct buffer_head * __getblk(struct block_device *, sector_t, int);
179 void __brelse(struct buffer_head *);
180 void __bforget(struct buffer_head *);
181 void __breadahead(struct block_device *, sector_t block, int size);
182 struct buffer_head *__bread(struct block_device *, sector_t block, int size);
183 struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
184 void free_buffer_head(struct buffer_head * bh);
185 void FASTCALL(unlock_buffer(struct buffer_head *bh));
186 void FASTCALL(__lock_buffer(struct buffer_head *bh));
187 void ll_rw_block(int, int, struct buffer_head * bh[]);
188 int sync_dirty_buffer(struct buffer_head *bh);
189 int submit_bh(int, struct buffer_head *);
190 void write_boundary_block(struct block_device *bdev,
191                         sector_t bblock, unsigned blocksize);
192
193 extern int buffer_heads_over_limit;
194
195 /*
196  * Generic address_space_operations implementations for buffer_head-backed
197  * address_spaces.
198  */
199 void block_invalidatepage(struct page *page, unsigned long offset);
200 int block_write_full_page(struct page *page, get_block_t *get_block,
201                                 struct writeback_control *wbc);
202 int block_read_full_page(struct page*, get_block_t*);
203 int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
204 int cont_prepare_write(struct page*, unsigned, unsigned, get_block_t*,
205                                 loff_t *);
206 int generic_cont_expand(struct inode *inode, loff_t size);
207 int generic_cont_expand_simple(struct inode *inode, loff_t size);
208 int block_commit_write(struct page *page, unsigned from, unsigned to);
209 void block_sync_page(struct page *);
210 sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
211 int generic_commit_write(struct file *, struct page *, unsigned, unsigned);
212 int block_truncate_page(struct address_space *, loff_t, get_block_t *);
213 int file_fsync(struct file *, struct dentry *, int);
214 int nobh_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
215 int nobh_commit_write(struct file *, struct page *, unsigned, unsigned);
216 int nobh_truncate_page(struct address_space *, loff_t);
217 int nobh_writepage(struct page *page, get_block_t *get_block,
218                         struct writeback_control *wbc);
219
220 void buffer_init(void);
221
222 /*
223  * inline definitions
224  */
225
226 static inline void attach_page_buffers(struct page *page,
227                 struct buffer_head *head)
228 {
229         page_cache_get(page);
230         SetPagePrivate(page);
231         set_page_private(page, (unsigned long)head);
232 }
233
234 static inline void get_bh(struct buffer_head *bh)
235 {
236         atomic_inc(&bh->b_count);
237 }
238
239 static inline void put_bh(struct buffer_head *bh)
240 {
241         smp_mb__before_atomic_dec();
242         atomic_dec(&bh->b_count);
243 }
244
245 static inline void brelse(struct buffer_head *bh)
246 {
247         if (bh)
248                 __brelse(bh);
249 }
250
251 static inline void bforget(struct buffer_head *bh)
252 {
253         if (bh)
254                 __bforget(bh);
255 }
256
257 static inline struct buffer_head *
258 sb_bread(struct super_block *sb, sector_t block)
259 {
260         return __bread(sb->s_bdev, block, sb->s_blocksize);
261 }
262
263 static inline void
264 sb_breadahead(struct super_block *sb, sector_t block)
265 {
266         __breadahead(sb->s_bdev, block, sb->s_blocksize);
267 }
268
269 static inline struct buffer_head *
270 sb_getblk(struct super_block *sb, sector_t block)
271 {
272         return __getblk(sb->s_bdev, block, sb->s_blocksize);
273 }
274
275 static inline struct buffer_head *
276 sb_find_get_block(struct super_block *sb, sector_t block)
277 {
278         return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
279 }
280
281 static inline void
282 map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
283 {
284         set_buffer_mapped(bh);
285         bh->b_bdev = sb->s_bdev;
286         bh->b_blocknr = block;
287         bh->b_size = sb->s_blocksize;
288 }
289
290 /*
291  * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into
292  * __wait_on_buffer() just to trip a debug check.  Because debug code in inline
293  * functions is bloaty.
294  */
295 static inline void wait_on_buffer(struct buffer_head *bh)
296 {
297         might_sleep();
298         if (buffer_locked(bh) || atomic_read(&bh->b_count) == 0)
299                 __wait_on_buffer(bh);
300 }
301
302 static inline void lock_buffer(struct buffer_head *bh)
303 {
304         might_sleep();
305         if (test_set_buffer_locked(bh))
306                 __lock_buffer(bh);
307 }
308
309 extern int __set_page_dirty_buffers(struct page *page);
310
311 #else /* CONFIG_BLOCK */
312
313 static inline void buffer_init(void) {}
314 static inline int try_to_free_buffers(struct page *page) { return 1; }
315 static inline int sync_blockdev(struct block_device *bdev) { return 0; }
316 static inline int inode_has_buffers(struct inode *inode) { return 0; }
317 static inline void invalidate_inode_buffers(struct inode *inode) {}
318 static inline int remove_inode_buffers(struct inode *inode) { return 1; }
319 static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
320 static inline void invalidate_bdev(struct block_device *bdev, int destroy_dirty_buffers) {}
321
322
323 #endif /* CONFIG_BLOCK */
324 #endif /* _LINUX_BUFFER_HEAD_H */