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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
17enum bh_state_bits {
18 BH_Uptodate, /* Contains valid data */
19 BH_Dirty, /* Is dirty */
20 BH_Lock, /* Is locked */
21 BH_Req, /* Has been submitted for I/O */
Nick Piggina3972202005-07-07 17:56:56 -070022 BH_Uptodate_Lock,/* Used by the first bh in a page, to serialise
23 * IO completion of other buffers in the page
24 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070025
26 BH_Mapped, /* Has a disk mapping */
27 BH_New, /* Disk mapping was newly created by get_block */
28 BH_Async_Read, /* Is under end_buffer_async_read I/O */
29 BH_Async_Write, /* Is under end_buffer_async_write I/O */
30 BH_Delay, /* Buffer is not yet allocated on disk */
31 BH_Boundary, /* Block is followed by a discontiguity */
32 BH_Write_EIO, /* I/O error on write */
33 BH_Ordered, /* ordered write */
34 BH_Eopnotsupp, /* operation not supported (barrier) */
35
36 BH_PrivateStart,/* not a state bit, but the first bit available
37 * for private allocation by other entities
38 */
39};
40
41#define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512)
42
43struct page;
44struct buffer_head;
45struct address_space;
46typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
47
48/*
49 * Keep related fields in common cachelines. The most commonly accessed
50 * field (b_state) goes at the start so the compiler does not generate
51 * indexed addressing for it.
52 */
53struct buffer_head {
54 /* First cache line: */
55 unsigned long b_state; /* buffer state bitmap (see above) */
56 struct buffer_head *b_this_page;/* circular list of page's buffers */
57 struct page *b_page; /* the page this bh is mapped to */
58 atomic_t b_count; /* users using this block */
59 u32 b_size; /* block size */
60
61 sector_t b_blocknr; /* block number */
62 char *b_data; /* pointer to data block */
63
64 struct block_device *b_bdev;
65 bh_end_io_t *b_end_io; /* I/O completion */
66 void *b_private; /* reserved for b_end_io */
67 struct list_head b_assoc_buffers; /* associated with another mapping */
68};
69
70/*
71 * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
72 * and buffer_foo() functions.
73 */
74#define BUFFER_FNS(bit, name) \
75static inline void set_buffer_##name(struct buffer_head *bh) \
76{ \
77 set_bit(BH_##bit, &(bh)->b_state); \
78} \
79static inline void clear_buffer_##name(struct buffer_head *bh) \
80{ \
81 clear_bit(BH_##bit, &(bh)->b_state); \
82} \
83static inline int buffer_##name(const struct buffer_head *bh) \
84{ \
85 return test_bit(BH_##bit, &(bh)->b_state); \
86}
87
88/*
89 * test_set_buffer_foo() and test_clear_buffer_foo()
90 */
91#define TAS_BUFFER_FNS(bit, name) \
92static inline int test_set_buffer_##name(struct buffer_head *bh) \
93{ \
94 return test_and_set_bit(BH_##bit, &(bh)->b_state); \
95} \
96static inline int test_clear_buffer_##name(struct buffer_head *bh) \
97{ \
98 return test_and_clear_bit(BH_##bit, &(bh)->b_state); \
99} \
100
101/*
102 * Emit the buffer bitops functions. Note that there are also functions
103 * of the form "mark_buffer_foo()". These are higher-level functions which
104 * do something in addition to setting a b_state bit.
105 */
106BUFFER_FNS(Uptodate, uptodate)
107BUFFER_FNS(Dirty, dirty)
108TAS_BUFFER_FNS(Dirty, dirty)
109BUFFER_FNS(Lock, locked)
110TAS_BUFFER_FNS(Lock, locked)
111BUFFER_FNS(Req, req)
112TAS_BUFFER_FNS(Req, req)
113BUFFER_FNS(Mapped, mapped)
114BUFFER_FNS(New, new)
115BUFFER_FNS(Async_Read, async_read)
116BUFFER_FNS(Async_Write, async_write)
117BUFFER_FNS(Delay, delay)
118BUFFER_FNS(Boundary, boundary)
119BUFFER_FNS(Write_EIO, write_io_error)
120BUFFER_FNS(Ordered, ordered)
121BUFFER_FNS(Eopnotsupp, eopnotsupp)
122
123#define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK)
124#define touch_buffer(bh) mark_page_accessed(bh->b_page)
125
126/* If we *know* page->private refers to buffer_heads */
127#define page_buffers(page) \
128 ({ \
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700129 BUG_ON(!PagePrivate(page)); \
130 ((struct buffer_head *)page_private(page)); \
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131 })
132#define page_has_buffers(page) PagePrivate(page)
133
134/*
135 * Declarations
136 */
137
138void FASTCALL(mark_buffer_dirty(struct buffer_head *bh));
139void init_buffer(struct buffer_head *, bh_end_io_t *, void *);
140void set_bh_page(struct buffer_head *bh,
141 struct page *page, unsigned long offset);
142int try_to_free_buffers(struct page *);
143struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
144 int retry);
145void create_empty_buffers(struct page *, unsigned long,
146 unsigned long b_state);
147void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
148void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
149void end_buffer_async_write(struct buffer_head *bh, int uptodate);
150
151/* Things to do with buffers at mapping->private_list */
152void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
153int inode_has_buffers(struct inode *);
154void invalidate_inode_buffers(struct inode *);
155int remove_inode_buffers(struct inode *inode);
156int sync_mapping_buffers(struct address_space *mapping);
157void unmap_underlying_metadata(struct block_device *bdev, sector_t block);
158
159void mark_buffer_async_write(struct buffer_head *bh);
160void invalidate_bdev(struct block_device *, int);
161int sync_blockdev(struct block_device *bdev);
162void __wait_on_buffer(struct buffer_head *);
163wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
164int fsync_bdev(struct block_device *);
165struct super_block *freeze_bdev(struct block_device *);
166void thaw_bdev(struct block_device *, struct super_block *);
167int fsync_super(struct super_block *);
168int fsync_no_super(struct block_device *);
169struct buffer_head *__find_get_block(struct block_device *, sector_t, int);
170struct buffer_head * __getblk(struct block_device *, sector_t, int);
171void __brelse(struct buffer_head *);
172void __bforget(struct buffer_head *);
173void __breadahead(struct block_device *, sector_t block, int size);
174struct buffer_head *__bread(struct block_device *, sector_t block, int size);
Al Virodd0fc662005-10-07 07:46:04 +0100175struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176void free_buffer_head(struct buffer_head * bh);
177void FASTCALL(unlock_buffer(struct buffer_head *bh));
178void FASTCALL(__lock_buffer(struct buffer_head *bh));
179void ll_rw_block(int, int, struct buffer_head * bh[]);
180int sync_dirty_buffer(struct buffer_head *bh);
181int submit_bh(int, struct buffer_head *);
182void write_boundary_block(struct block_device *bdev,
183 sector_t bblock, unsigned blocksize);
184
185extern int buffer_heads_over_limit;
186
187/*
188 * Generic address_space_operations implementations for buffer_head-backed
189 * address_spaces.
190 */
Al Viro27496a82005-10-21 03:20:48 -0400191int try_to_release_page(struct page * page, gfp_t gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192int block_invalidatepage(struct page *page, unsigned long offset);
Jan Karaaaa40592005-10-30 15:00:16 -0800193int do_invalidatepage(struct page *page, unsigned long offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194int block_write_full_page(struct page *page, get_block_t *get_block,
195 struct writeback_control *wbc);
196int block_read_full_page(struct page*, get_block_t*);
197int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
198int cont_prepare_write(struct page*, unsigned, unsigned, get_block_t*,
199 loff_t *);
200int generic_cont_expand(struct inode *inode, loff_t size) ;
201int block_commit_write(struct page *page, unsigned from, unsigned to);
202int block_sync_page(struct page *);
203sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
204int generic_commit_write(struct file *, struct page *, unsigned, unsigned);
205int block_truncate_page(struct address_space *, loff_t, get_block_t *);
206int file_fsync(struct file *, struct dentry *, int);
207int nobh_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
208int nobh_commit_write(struct file *, struct page *, unsigned, unsigned);
209int nobh_truncate_page(struct address_space *, loff_t);
210int nobh_writepage(struct page *page, get_block_t *get_block,
211 struct writeback_control *wbc);
212
213
214/*
215 * inline definitions
216 */
217
218static inline void attach_page_buffers(struct page *page,
219 struct buffer_head *head)
220{
221 page_cache_get(page);
222 SetPagePrivate(page);
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700223 set_page_private(page, (unsigned long)head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224}
225
226static inline void get_bh(struct buffer_head *bh)
227{
228 atomic_inc(&bh->b_count);
229}
230
231static inline void put_bh(struct buffer_head *bh)
232{
233 smp_mb__before_atomic_dec();
234 atomic_dec(&bh->b_count);
235}
236
237static inline void brelse(struct buffer_head *bh)
238{
239 if (bh)
240 __brelse(bh);
241}
242
243static inline void bforget(struct buffer_head *bh)
244{
245 if (bh)
246 __bforget(bh);
247}
248
249static inline struct buffer_head *
250sb_bread(struct super_block *sb, sector_t block)
251{
252 return __bread(sb->s_bdev, block, sb->s_blocksize);
253}
254
255static inline void
256sb_breadahead(struct super_block *sb, sector_t block)
257{
258 __breadahead(sb->s_bdev, block, sb->s_blocksize);
259}
260
261static inline struct buffer_head *
262sb_getblk(struct super_block *sb, sector_t block)
263{
264 return __getblk(sb->s_bdev, block, sb->s_blocksize);
265}
266
267static inline struct buffer_head *
268sb_find_get_block(struct super_block *sb, sector_t block)
269{
270 return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
271}
272
273static inline void
274map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
275{
276 set_buffer_mapped(bh);
277 bh->b_bdev = sb->s_bdev;
278 bh->b_blocknr = block;
279}
280
281/*
282 * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into
283 * __wait_on_buffer() just to trip a debug check. Because debug code in inline
284 * functions is bloaty.
285 */
286static inline void wait_on_buffer(struct buffer_head *bh)
287{
288 might_sleep();
289 if (buffer_locked(bh) || atomic_read(&bh->b_count) == 0)
290 __wait_on_buffer(bh);
291}
292
293static inline void lock_buffer(struct buffer_head *bh)
294{
295 might_sleep();
296 if (test_set_buffer_locked(bh))
297 __lock_buffer(bh);
298}
299
300#endif /* _LINUX_BUFFER_HEAD_H */