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-rw-r--r--include/linux/buffer_head.h296
1 files changed, 296 insertions, 0 deletions
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
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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
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 */
22
23 BH_Mapped, /* Has a disk mapping */
24 BH_New, /* Disk mapping was newly created by get_block */
25 BH_Async_Read, /* Is under end_buffer_async_read I/O */
26 BH_Async_Write, /* Is under end_buffer_async_write I/O */
27 BH_Delay, /* Buffer is not yet allocated on disk */
28 BH_Boundary, /* Block is followed by a discontiguity */
29 BH_Write_EIO, /* I/O error on write */
30 BH_Ordered, /* ordered write */
31 BH_Eopnotsupp, /* operation not supported (barrier) */
32
33 BH_PrivateStart,/* not a state bit, but the first bit available
34 * for private allocation by other entities
35 */
36};
37
38#define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512)
39
40struct page;
41struct buffer_head;
42struct address_space;
43typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
44
45/*
46 * Keep related fields in common cachelines. The most commonly accessed
47 * field (b_state) goes at the start so the compiler does not generate
48 * indexed addressing for it.
49 */
50struct buffer_head {
51 /* First cache line: */
52 unsigned long b_state; /* buffer state bitmap (see above) */
53 struct buffer_head *b_this_page;/* circular list of page's buffers */
54 struct page *b_page; /* the page this bh is mapped to */
55 atomic_t b_count; /* users using this block */
56 u32 b_size; /* block size */
57
58 sector_t b_blocknr; /* block number */
59 char *b_data; /* pointer to data block */
60
61 struct block_device *b_bdev;
62 bh_end_io_t *b_end_io; /* I/O completion */
63 void *b_private; /* reserved for b_end_io */
64 struct list_head b_assoc_buffers; /* associated with another mapping */
65};
66
67/*
68 * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
69 * and buffer_foo() functions.
70 */
71#define BUFFER_FNS(bit, name) \
72static inline void set_buffer_##name(struct buffer_head *bh) \
73{ \
74 set_bit(BH_##bit, &(bh)->b_state); \
75} \
76static inline void clear_buffer_##name(struct buffer_head *bh) \
77{ \
78 clear_bit(BH_##bit, &(bh)->b_state); \
79} \
80static inline int buffer_##name(const struct buffer_head *bh) \
81{ \
82 return test_bit(BH_##bit, &(bh)->b_state); \
83}
84
85/*
86 * test_set_buffer_foo() and test_clear_buffer_foo()
87 */
88#define TAS_BUFFER_FNS(bit, name) \
89static inline int test_set_buffer_##name(struct buffer_head *bh) \
90{ \
91 return test_and_set_bit(BH_##bit, &(bh)->b_state); \
92} \
93static inline int test_clear_buffer_##name(struct buffer_head *bh) \
94{ \
95 return test_and_clear_bit(BH_##bit, &(bh)->b_state); \
96} \
97
98/*
99 * Emit the buffer bitops functions. Note that there are also functions
100 * of the form "mark_buffer_foo()". These are higher-level functions which
101 * do something in addition to setting a b_state bit.
102 */
103BUFFER_FNS(Uptodate, uptodate)
104BUFFER_FNS(Dirty, dirty)
105TAS_BUFFER_FNS(Dirty, dirty)
106BUFFER_FNS(Lock, locked)
107TAS_BUFFER_FNS(Lock, locked)
108BUFFER_FNS(Req, req)
109TAS_BUFFER_FNS(Req, req)
110BUFFER_FNS(Mapped, mapped)
111BUFFER_FNS(New, new)
112BUFFER_FNS(Async_Read, async_read)
113BUFFER_FNS(Async_Write, async_write)
114BUFFER_FNS(Delay, delay)
115BUFFER_FNS(Boundary, boundary)
116BUFFER_FNS(Write_EIO, write_io_error)
117BUFFER_FNS(Ordered, ordered)
118BUFFER_FNS(Eopnotsupp, eopnotsupp)
119
120#define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK)
121#define touch_buffer(bh) mark_page_accessed(bh->b_page)
122
123/* If we *know* page->private refers to buffer_heads */
124#define page_buffers(page) \
125 ({ \
126 BUG_ON(!PagePrivate(page)); \
127 ((struct buffer_head *)(page)->private); \
128 })
129#define page_has_buffers(page) PagePrivate(page)
130
131/*
132 * Declarations
133 */
134
135void FASTCALL(mark_buffer_dirty(struct buffer_head *bh));
136void init_buffer(struct buffer_head *, bh_end_io_t *, void *);
137void set_bh_page(struct buffer_head *bh,
138 struct page *page, unsigned long offset);
139int try_to_free_buffers(struct page *);
140struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
141 int retry);
142void create_empty_buffers(struct page *, unsigned long,
143 unsigned long b_state);
144void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
145void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
146void end_buffer_async_write(struct buffer_head *bh, int uptodate);
147
148/* Things to do with buffers at mapping->private_list */
149void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
150int inode_has_buffers(struct inode *);
151void invalidate_inode_buffers(struct inode *);
152int remove_inode_buffers(struct inode *inode);
153int sync_mapping_buffers(struct address_space *mapping);
154void unmap_underlying_metadata(struct block_device *bdev, sector_t block);
155
156void mark_buffer_async_write(struct buffer_head *bh);
157void invalidate_bdev(struct block_device *, int);
158int sync_blockdev(struct block_device *bdev);
159void __wait_on_buffer(struct buffer_head *);
160wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
161int fsync_bdev(struct block_device *);
162struct super_block *freeze_bdev(struct block_device *);
163void thaw_bdev(struct block_device *, struct super_block *);
164int fsync_super(struct super_block *);
165int fsync_no_super(struct block_device *);
166struct buffer_head *__find_get_block(struct block_device *, sector_t, int);
167struct buffer_head * __getblk(struct block_device *, sector_t, int);
168void __brelse(struct buffer_head *);
169void __bforget(struct buffer_head *);
170void __breadahead(struct block_device *, sector_t block, int size);
171struct buffer_head *__bread(struct block_device *, sector_t block, int size);
172struct buffer_head *alloc_buffer_head(unsigned int __nocast gfp_flags);
173void free_buffer_head(struct buffer_head * bh);
174void FASTCALL(unlock_buffer(struct buffer_head *bh));
175void FASTCALL(__lock_buffer(struct buffer_head *bh));
176void ll_rw_block(int, int, struct buffer_head * bh[]);
177int sync_dirty_buffer(struct buffer_head *bh);
178int submit_bh(int, struct buffer_head *);
179void write_boundary_block(struct block_device *bdev,
180 sector_t bblock, unsigned blocksize);
181
182extern int buffer_heads_over_limit;
183
184/*
185 * Generic address_space_operations implementations for buffer_head-backed
186 * address_spaces.
187 */
188int try_to_release_page(struct page * page, int gfp_mask);
189int block_invalidatepage(struct page *page, unsigned long offset);
190int block_write_full_page(struct page *page, get_block_t *get_block,
191 struct writeback_control *wbc);
192int block_read_full_page(struct page*, get_block_t*);
193int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
194int cont_prepare_write(struct page*, unsigned, unsigned, get_block_t*,
195 loff_t *);
196int generic_cont_expand(struct inode *inode, loff_t size) ;
197int block_commit_write(struct page *page, unsigned from, unsigned to);
198int block_sync_page(struct page *);
199sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
200int generic_commit_write(struct file *, struct page *, unsigned, unsigned);
201int block_truncate_page(struct address_space *, loff_t, get_block_t *);
202int file_fsync(struct file *, struct dentry *, int);
203int nobh_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
204int nobh_commit_write(struct file *, struct page *, unsigned, unsigned);
205int nobh_truncate_page(struct address_space *, loff_t);
206int nobh_writepage(struct page *page, get_block_t *get_block,
207 struct writeback_control *wbc);
208
209
210/*
211 * inline definitions
212 */
213
214static inline void attach_page_buffers(struct page *page,
215 struct buffer_head *head)
216{
217 page_cache_get(page);
218 SetPagePrivate(page);
219 page->private = (unsigned long)head;
220}
221
222static inline void get_bh(struct buffer_head *bh)
223{
224 atomic_inc(&bh->b_count);
225}
226
227static inline void put_bh(struct buffer_head *bh)
228{
229 smp_mb__before_atomic_dec();
230 atomic_dec(&bh->b_count);
231}
232
233static inline void brelse(struct buffer_head *bh)
234{
235 if (bh)
236 __brelse(bh);
237}
238
239static inline void bforget(struct buffer_head *bh)
240{
241 if (bh)
242 __bforget(bh);
243}
244
245static inline struct buffer_head *
246sb_bread(struct super_block *sb, sector_t block)
247{
248 return __bread(sb->s_bdev, block, sb->s_blocksize);
249}
250
251static inline void
252sb_breadahead(struct super_block *sb, sector_t block)
253{
254 __breadahead(sb->s_bdev, block, sb->s_blocksize);
255}
256
257static inline struct buffer_head *
258sb_getblk(struct super_block *sb, sector_t block)
259{
260 return __getblk(sb->s_bdev, block, sb->s_blocksize);
261}
262
263static inline struct buffer_head *
264sb_find_get_block(struct super_block *sb, sector_t block)
265{
266 return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
267}
268
269static inline void
270map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
271{
272 set_buffer_mapped(bh);
273 bh->b_bdev = sb->s_bdev;
274 bh->b_blocknr = block;
275}
276
277/*
278 * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into
279 * __wait_on_buffer() just to trip a debug check. Because debug code in inline
280 * functions is bloaty.
281 */
282static inline void wait_on_buffer(struct buffer_head *bh)
283{
284 might_sleep();
285 if (buffer_locked(bh) || atomic_read(&bh->b_count) == 0)
286 __wait_on_buffer(bh);
287}
288
289static inline void lock_buffer(struct buffer_head *bh)
290{
291 might_sleep();
292 if (test_set_buffer_locked(bh))
293 __lock_buffer(bh);
294}
295
296#endif /* _LINUX_BUFFER_HEAD_H */
generated by cgit v1.2.2 (git 2.25.0) at 2026-04-17 06:23:13 -0400