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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);
Chris Mason35c80d52009-04-15 13:22:38 -0400158void end_buffer_async_write(struct buffer_head *bh, int uptodate);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159
160/* Things to do with buffers at mapping->private_list */
161void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
162int inode_has_buffers(struct inode *);
163void invalidate_inode_buffers(struct inode *);
164int remove_inode_buffers(struct inode *inode);
165int sync_mapping_buffers(struct address_space *mapping);
166void unmap_underlying_metadata(struct block_device *bdev, sector_t block);
167
168void mark_buffer_async_write(struct buffer_head *bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169void __wait_on_buffer(struct buffer_head *);
170wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -0800171struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block,
172 unsigned size);
173struct buffer_head *__getblk(struct block_device *bdev, sector_t block,
174 unsigned size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175void __brelse(struct buffer_head *);
176void __bforget(struct buffer_head *);
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -0800177void __breadahead(struct block_device *, sector_t block, unsigned int size);
178struct buffer_head *__bread(struct block_device *, sector_t block, unsigned size);
Peter Zijlstraf9a14392007-05-06 14:49:55 -0700179void invalidate_bh_lrus(void);
Al Virodd0fc662005-10-07 07:46:04 +0100180struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181void free_buffer_head(struct buffer_head * bh);
Harvey Harrisonb3c97522008-02-13 15:03:15 -0800182void unlock_buffer(struct buffer_head *bh);
183void __lock_buffer(struct buffer_head *bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184void ll_rw_block(int, int, struct buffer_head * bh[]);
185int sync_dirty_buffer(struct buffer_head *bh);
186int submit_bh(int, struct buffer_head *);
187void write_boundary_block(struct block_device *bdev,
188 sector_t bblock, unsigned blocksize);
Aneesh Kumar K.V389d1b02008-01-28 23:58:26 -0500189int bh_uptodate_or_lock(struct buffer_head *bh);
190int bh_submit_read(struct buffer_head *bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191
192extern int buffer_heads_over_limit;
193
194/*
195 * Generic address_space_operations implementations for buffer_head-backed
196 * address_spaces.
197 */
NeilBrown2ff28e22006-03-26 01:37:18 -0800198void block_invalidatepage(struct page *page, unsigned long offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199int block_write_full_page(struct page *page, get_block_t *get_block,
200 struct writeback_control *wbc);
Chris Mason35c80d52009-04-15 13:22:38 -0400201int block_write_full_page_endio(struct page *page, get_block_t *get_block,
202 struct writeback_control *wbc, bh_end_io_t *handler);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203int block_read_full_page(struct page*, get_block_t*);
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -0700204int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc,
205 unsigned long from);
Nick Pigginafddba42007-10-16 01:25:01 -0700206int block_write_begin(struct file *, struct address_space *,
207 loff_t, unsigned, unsigned,
208 struct page **, void **, get_block_t*);
209int block_write_end(struct file *, struct address_space *,
210 loff_t, unsigned, unsigned,
211 struct page *, void *);
212int generic_write_end(struct file *, struct address_space *,
213 loff_t, unsigned, unsigned,
214 struct page *, void *);
215void page_zero_new_buffers(struct page *page, unsigned from, unsigned to);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
Nick Piggin89e10782007-10-16 01:25:07 -0700217int cont_write_begin(struct file *, struct address_space *, loff_t,
218 unsigned, unsigned, struct page **, void **,
219 get_block_t *, loff_t *);
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -0800220int generic_cont_expand_simple(struct inode *inode, loff_t size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221int block_commit_write(struct page *page, unsigned from, unsigned to);
Nick Pigginc2ec1752009-03-31 15:23:21 -0700222int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
David Chinner54171692007-07-19 17:39:55 +1000223 get_block_t get_block);
NeilBrown3978d712006-03-26 01:37:17 -0800224void block_sync_page(struct page *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700226int block_truncate_page(struct address_space *, loff_t, get_block_t *);
227int file_fsync(struct file *, struct dentry *, int);
Nick Piggin03158cd2007-10-16 01:25:25 -0700228int nobh_write_begin(struct file *, struct address_space *,
229 loff_t, unsigned, unsigned,
230 struct page **, void **, get_block_t*);
231int nobh_write_end(struct file *, struct address_space *,
232 loff_t, unsigned, unsigned,
233 struct page *, void *);
234int nobh_truncate_page(struct address_space *, loff_t, get_block_t *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235int nobh_writepage(struct page *page, get_block_t *get_block,
236 struct writeback_control *wbc);
237
Adrian Bunkb6cd0b72006-06-27 02:53:54 -0700238void buffer_init(void);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239
240/*
241 * inline definitions
242 */
243
244static inline void attach_page_buffers(struct page *page,
245 struct buffer_head *head)
246{
247 page_cache_get(page);
248 SetPagePrivate(page);
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700249 set_page_private(page, (unsigned long)head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250}
251
252static inline void get_bh(struct buffer_head *bh)
253{
254 atomic_inc(&bh->b_count);
255}
256
257static inline void put_bh(struct buffer_head *bh)
258{
259 smp_mb__before_atomic_dec();
260 atomic_dec(&bh->b_count);
261}
262
263static inline void brelse(struct buffer_head *bh)
264{
265 if (bh)
266 __brelse(bh);
267}
268
269static inline void bforget(struct buffer_head *bh)
270{
271 if (bh)
272 __bforget(bh);
273}
274
275static inline struct buffer_head *
276sb_bread(struct super_block *sb, sector_t block)
277{
278 return __bread(sb->s_bdev, block, sb->s_blocksize);
279}
280
281static inline void
282sb_breadahead(struct super_block *sb, sector_t block)
283{
284 __breadahead(sb->s_bdev, block, sb->s_blocksize);
285}
286
287static inline struct buffer_head *
288sb_getblk(struct super_block *sb, sector_t block)
289{
290 return __getblk(sb->s_bdev, block, sb->s_blocksize);
291}
292
293static inline struct buffer_head *
294sb_find_get_block(struct super_block *sb, sector_t block)
295{
296 return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
297}
298
299static inline void
300map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
301{
302 set_buffer_mapped(bh);
303 bh->b_bdev = sb->s_bdev;
304 bh->b_blocknr = block;
Badari Pulavartyb0cf2322006-03-26 01:38:00 -0800305 bh->b_size = sb->s_blocksize;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306}
307
308/*
309 * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into
310 * __wait_on_buffer() just to trip a debug check. Because debug code in inline
311 * functions is bloaty.
312 */
313static inline void wait_on_buffer(struct buffer_head *bh)
314{
315 might_sleep();
316 if (buffer_locked(bh) || atomic_read(&bh->b_count) == 0)
317 __wait_on_buffer(bh);
318}
319
Nick Pigginca5de402008-08-02 12:02:13 +0200320static inline int trylock_buffer(struct buffer_head *bh)
321{
Nick Piggin51b07fc2008-10-18 20:27:00 -0700322 return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));
Nick Pigginca5de402008-08-02 12:02:13 +0200323}
324
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325static inline void lock_buffer(struct buffer_head *bh)
326{
327 might_sleep();
Nick Pigginca5de402008-08-02 12:02:13 +0200328 if (!trylock_buffer(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329 __lock_buffer(bh);
330}
331
David Howellscf9a2ae2006-08-29 19:05:54 +0100332extern int __set_page_dirty_buffers(struct page *page);
David Howells93614012006-09-30 20:45:40 +0200333
334#else /* CONFIG_BLOCK */
335
336static inline void buffer_init(void) {}
337static inline int try_to_free_buffers(struct page *page) { return 1; }
David Howells93614012006-09-30 20:45:40 +0200338static inline int inode_has_buffers(struct inode *inode) { return 0; }
339static inline void invalidate_inode_buffers(struct inode *inode) {}
340static inline int remove_inode_buffers(struct inode *inode) { return 1; }
341static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
David Howells93614012006-09-30 20:45:40 +0200342
343#endif /* CONFIG_BLOCK */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344#endif /* _LINUX_BUFFER_HEAD_H */