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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
David Howells93614012006-09-30 20:45:40 +020017#ifdef CONFIG_BLOCK
18
Linus Torvalds1da177e2005-04-16 15:20:36 -070019enum 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 */
Nick Piggina3972202005-07-07 17:56:56 -070024 BH_Uptodate_Lock,/* Used by the first bh in a page, to serialise
25 * IO completion of other buffers in the page
26 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070027
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) */
David Chinner33a266d2007-02-12 00:51:41 -080037 BH_Unwritten, /* Buffer is allocated on disk but not written */
Keith Mannthey08bafc02008-11-25 10:24:35 +010038 BH_Quiet, /* Buffer Error Prinks to be quiet */
Linus Torvalds1da177e2005-04-16 15:20:36 -070039
40 BH_PrivateStart,/* not a state bit, but the first bit available
41 * for private allocation by other entities
42 */
43};
44
45#define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512)
46
47struct page;
48struct buffer_head;
49struct address_space;
50typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
51
52/*
Badari Pulavarty205f87f2006-03-26 01:38:00 -080053 * Historically, a buffer_head was used to map a single block
54 * within a page, and of course as the unit of I/O through the
55 * filesystem and block layers. Nowadays the basic I/O unit
56 * is the bio, and buffer_heads are used for extracting block
57 * mappings (via a get_block_t call), for tracking state within
58 * a page (via a page_mapping) and for wrapping bio submission
59 * for backward compatibility reasons (e.g. submit_bh).
Linus Torvalds1da177e2005-04-16 15:20:36 -070060 */
61struct buffer_head {
Linus Torvalds1da177e2005-04-16 15:20:36 -070062 unsigned long b_state; /* buffer state bitmap (see above) */
63 struct buffer_head *b_this_page;/* circular list of page's buffers */
64 struct page *b_page; /* the page this bh is mapped to */
Linus Torvalds1da177e2005-04-16 15:20:36 -070065
Badari Pulavarty205f87f2006-03-26 01:38:00 -080066 sector_t b_blocknr; /* start block number */
67 size_t b_size; /* size of mapping */
68 char *b_data; /* pointer to data within the page */
Linus Torvalds1da177e2005-04-16 15:20:36 -070069
70 struct block_device *b_bdev;
71 bh_end_io_t *b_end_io; /* I/O completion */
72 void *b_private; /* reserved for b_end_io */
73 struct list_head b_assoc_buffers; /* associated with another mapping */
Jan Kara58ff4072006-10-17 00:10:19 -070074 struct address_space *b_assoc_map; /* mapping this buffer is
75 associated with */
Badari Pulavarty205f87f2006-03-26 01:38:00 -080076 atomic_t b_count; /* users using this buffer_head */
Linus Torvalds1da177e2005-04-16 15:20:36 -070077};
78
79/*
80 * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
81 * and buffer_foo() functions.
82 */
83#define BUFFER_FNS(bit, name) \
84static inline void set_buffer_##name(struct buffer_head *bh) \
85{ \
86 set_bit(BH_##bit, &(bh)->b_state); \
87} \
88static inline void clear_buffer_##name(struct buffer_head *bh) \
89{ \
90 clear_bit(BH_##bit, &(bh)->b_state); \
91} \
92static inline int buffer_##name(const struct buffer_head *bh) \
93{ \
94 return test_bit(BH_##bit, &(bh)->b_state); \
95}
96
97/*
98 * test_set_buffer_foo() and test_clear_buffer_foo()
99 */
100#define TAS_BUFFER_FNS(bit, name) \
101static inline int test_set_buffer_##name(struct buffer_head *bh) \
102{ \
103 return test_and_set_bit(BH_##bit, &(bh)->b_state); \
104} \
105static inline int test_clear_buffer_##name(struct buffer_head *bh) \
106{ \
107 return test_and_clear_bit(BH_##bit, &(bh)->b_state); \
108} \
109
110/*
111 * Emit the buffer bitops functions. Note that there are also functions
112 * of the form "mark_buffer_foo()". These are higher-level functions which
113 * do something in addition to setting a b_state bit.
114 */
115BUFFER_FNS(Uptodate, uptodate)
116BUFFER_FNS(Dirty, dirty)
117TAS_BUFFER_FNS(Dirty, dirty)
118BUFFER_FNS(Lock, locked)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119BUFFER_FNS(Req, req)
120TAS_BUFFER_FNS(Req, req)
121BUFFER_FNS(Mapped, mapped)
122BUFFER_FNS(New, new)
123BUFFER_FNS(Async_Read, async_read)
124BUFFER_FNS(Async_Write, async_write)
125BUFFER_FNS(Delay, delay)
126BUFFER_FNS(Boundary, boundary)
127BUFFER_FNS(Write_EIO, write_io_error)
128BUFFER_FNS(Ordered, ordered)
129BUFFER_FNS(Eopnotsupp, eopnotsupp)
David Chinner33a266d2007-02-12 00:51:41 -0800130BUFFER_FNS(Unwritten, unwritten)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131
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 ({ \
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700138 BUG_ON(!PagePrivate(page)); \
139 ((struct buffer_head *)page_private(page)); \
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140 })
141#define page_has_buffers(page) PagePrivate(page)
142
143/*
144 * Declarations
145 */
146
Harvey Harrisonb3c97522008-02-13 15:03:15 -0800147void mark_buffer_dirty(struct buffer_head *bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700148void init_buffer(struct buffer_head *, bh_end_io_t *, void *);
149void set_bh_page(struct buffer_head *bh,
150 struct page *page, unsigned long offset);
151int try_to_free_buffers(struct page *);
152struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
153 int retry);
154void create_empty_buffers(struct page *, unsigned long,
155 unsigned long b_state);
156void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
157void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158
159/* Things to do with buffers at mapping->private_list */
160void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
161int inode_has_buffers(struct inode *);
162void invalidate_inode_buffers(struct inode *);
163int remove_inode_buffers(struct inode *inode);
164int sync_mapping_buffers(struct address_space *mapping);
165void unmap_underlying_metadata(struct block_device *bdev, sector_t block);
166
167void mark_buffer_async_write(struct buffer_head *bh);
Peter Zijlstraf98393a2007-05-06 14:49:54 -0700168void invalidate_bdev(struct block_device *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169int sync_blockdev(struct block_device *bdev);
170void __wait_on_buffer(struct buffer_head *);
171wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
172int fsync_bdev(struct block_device *);
173struct super_block *freeze_bdev(struct block_device *);
174void thaw_bdev(struct block_device *, struct super_block *);
175int fsync_super(struct super_block *);
176int fsync_no_super(struct block_device *);
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -0800177struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block,
178 unsigned size);
179struct buffer_head *__getblk(struct block_device *bdev, sector_t block,
180 unsigned size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181void __brelse(struct buffer_head *);
182void __bforget(struct buffer_head *);
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -0800183void __breadahead(struct block_device *, sector_t block, unsigned int size);
184struct buffer_head *__bread(struct block_device *, sector_t block, unsigned size);
Peter Zijlstraf9a14392007-05-06 14:49:55 -0700185void invalidate_bh_lrus(void);
Al Virodd0fc662005-10-07 07:46:04 +0100186struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187void free_buffer_head(struct buffer_head * bh);
Harvey Harrisonb3c97522008-02-13 15:03:15 -0800188void unlock_buffer(struct buffer_head *bh);
189void __lock_buffer(struct buffer_head *bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190void ll_rw_block(int, int, struct buffer_head * bh[]);
191int sync_dirty_buffer(struct buffer_head *bh);
192int submit_bh(int, struct buffer_head *);
193void write_boundary_block(struct block_device *bdev,
194 sector_t bblock, unsigned blocksize);
Aneesh Kumar K.V389d1b02008-01-28 23:58:26 -0500195int bh_uptodate_or_lock(struct buffer_head *bh);
196int bh_submit_read(struct buffer_head *bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197
198extern int buffer_heads_over_limit;
199
200/*
201 * Generic address_space_operations implementations for buffer_head-backed
202 * address_spaces.
203 */
NeilBrown2ff28e22006-03-26 01:37:18 -0800204void block_invalidatepage(struct page *page, unsigned long offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205int block_write_full_page(struct page *page, get_block_t *get_block,
206 struct writeback_control *wbc);
207int block_read_full_page(struct page*, get_block_t*);
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -0700208int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc,
209 unsigned long from);
Nick Pigginafddba42007-10-16 01:25:01 -0700210int block_write_begin(struct file *, struct address_space *,
211 loff_t, unsigned, unsigned,
212 struct page **, void **, get_block_t*);
213int block_write_end(struct file *, struct address_space *,
214 loff_t, unsigned, unsigned,
215 struct page *, void *);
216int generic_write_end(struct file *, struct address_space *,
217 loff_t, unsigned, unsigned,
218 struct page *, void *);
219void page_zero_new_buffers(struct page *page, unsigned from, unsigned to);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
Nick Piggin89e10782007-10-16 01:25:07 -0700221int cont_write_begin(struct file *, struct address_space *, loff_t,
222 unsigned, unsigned, struct page **, void **,
223 get_block_t *, loff_t *);
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -0800224int generic_cont_expand_simple(struct inode *inode, loff_t size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225int block_commit_write(struct page *page, unsigned from, unsigned to);
David Chinner54171692007-07-19 17:39:55 +1000226int block_page_mkwrite(struct vm_area_struct *vma, struct page *page,
227 get_block_t get_block);
NeilBrown3978d7172006-03-26 01:37:17 -0800228void block_sync_page(struct page *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700230int block_truncate_page(struct address_space *, loff_t, get_block_t *);
231int file_fsync(struct file *, struct dentry *, int);
Nick Piggin03158cd2007-10-16 01:25:25 -0700232int nobh_write_begin(struct file *, struct address_space *,
233 loff_t, unsigned, unsigned,
234 struct page **, void **, get_block_t*);
235int nobh_write_end(struct file *, struct address_space *,
236 loff_t, unsigned, unsigned,
237 struct page *, void *);
238int nobh_truncate_page(struct address_space *, loff_t, get_block_t *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239int nobh_writepage(struct page *page, get_block_t *get_block,
240 struct writeback_control *wbc);
241
Adrian Bunkb6cd0b72006-06-27 02:53:54 -0700242void buffer_init(void);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700243
244/*
245 * inline definitions
246 */
247
248static inline void attach_page_buffers(struct page *page,
249 struct buffer_head *head)
250{
251 page_cache_get(page);
252 SetPagePrivate(page);
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700253 set_page_private(page, (unsigned long)head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254}
255
256static inline void get_bh(struct buffer_head *bh)
257{
258 atomic_inc(&bh->b_count);
259}
260
261static inline void put_bh(struct buffer_head *bh)
262{
263 smp_mb__before_atomic_dec();
264 atomic_dec(&bh->b_count);
265}
266
267static inline void brelse(struct buffer_head *bh)
268{
269 if (bh)
270 __brelse(bh);
271}
272
273static inline void bforget(struct buffer_head *bh)
274{
275 if (bh)
276 __bforget(bh);
277}
278
279static inline struct buffer_head *
280sb_bread(struct super_block *sb, sector_t block)
281{
282 return __bread(sb->s_bdev, block, sb->s_blocksize);
283}
284
285static inline void
286sb_breadahead(struct super_block *sb, sector_t block)
287{
288 __breadahead(sb->s_bdev, block, sb->s_blocksize);
289}
290
291static inline struct buffer_head *
292sb_getblk(struct super_block *sb, sector_t block)
293{
294 return __getblk(sb->s_bdev, block, sb->s_blocksize);
295}
296
297static inline struct buffer_head *
298sb_find_get_block(struct super_block *sb, sector_t block)
299{
300 return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
301}
302
303static inline void
304map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
305{
306 set_buffer_mapped(bh);
307 bh->b_bdev = sb->s_bdev;
308 bh->b_blocknr = block;
Badari Pulavartyb0cf2322006-03-26 01:38:00 -0800309 bh->b_size = sb->s_blocksize;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310}
311
312/*
313 * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into
314 * __wait_on_buffer() just to trip a debug check. Because debug code in inline
315 * functions is bloaty.
316 */
317static inline void wait_on_buffer(struct buffer_head *bh)
318{
319 might_sleep();
320 if (buffer_locked(bh) || atomic_read(&bh->b_count) == 0)
321 __wait_on_buffer(bh);
322}
323
Nick Pigginca5de402008-08-02 12:02:13 +0200324static inline int trylock_buffer(struct buffer_head *bh)
325{
Nick Piggin51b07fc2008-10-18 20:27:00 -0700326 return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));
Nick Pigginca5de402008-08-02 12:02:13 +0200327}
328
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329static inline void lock_buffer(struct buffer_head *bh)
330{
331 might_sleep();
Nick Pigginca5de402008-08-02 12:02:13 +0200332 if (!trylock_buffer(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333 __lock_buffer(bh);
334}
335
David Howellscf9a2ae2006-08-29 19:05:54 +0100336extern int __set_page_dirty_buffers(struct page *page);
David Howells93614012006-09-30 20:45:40 +0200337
338#else /* CONFIG_BLOCK */
339
340static inline void buffer_init(void) {}
341static inline int try_to_free_buffers(struct page *page) { return 1; }
342static inline int sync_blockdev(struct block_device *bdev) { return 0; }
343static inline int inode_has_buffers(struct inode *inode) { return 0; }
344static inline void invalidate_inode_buffers(struct inode *inode) {}
345static inline int remove_inode_buffers(struct inode *inode) { return 1; }
346static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
Peter Zijlstraf98393a2007-05-06 14:49:54 -0700347static inline void invalidate_bdev(struct block_device *bdev) {}
David Howells93614012006-09-30 20:45:40 +0200348
349
350#endif /* CONFIG_BLOCK */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351#endif /* _LINUX_BUFFER_HEAD_H */