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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 */
David Chinner33a266d2007-02-12 00:51:41 -080035 BH_Unwritten, /* Buffer is allocated on disk but not written */
Keith Mannthey08bafc02008-11-25 10:24:35 +010036 BH_Quiet, /* Buffer Error Prinks to be quiet */
Linus Torvalds1da177e2005-04-16 15:20:36 -070037
38 BH_PrivateStart,/* not a state bit, but the first bit available
39 * for private allocation by other entities
40 */
41};
42
43#define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512)
44
45struct page;
46struct buffer_head;
47struct address_space;
48typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
49
50/*
Badari Pulavarty205f87f2006-03-26 01:38:00 -080051 * Historically, a buffer_head was used to map a single block
52 * within a page, and of course as the unit of I/O through the
53 * filesystem and block layers. Nowadays the basic I/O unit
54 * is the bio, and buffer_heads are used for extracting block
55 * mappings (via a get_block_t call), for tracking state within
56 * a page (via a page_mapping) and for wrapping bio submission
57 * for backward compatibility reasons (e.g. submit_bh).
Linus Torvalds1da177e2005-04-16 15:20:36 -070058 */
59struct buffer_head {
Linus Torvalds1da177e2005-04-16 15:20:36 -070060 unsigned long b_state; /* buffer state bitmap (see above) */
61 struct buffer_head *b_this_page;/* circular list of page's buffers */
62 struct page *b_page; /* the page this bh is mapped to */
Linus Torvalds1da177e2005-04-16 15:20:36 -070063
Badari Pulavarty205f87f2006-03-26 01:38:00 -080064 sector_t b_blocknr; /* start block number */
65 size_t b_size; /* size of mapping */
66 char *b_data; /* pointer to data within the page */
Linus Torvalds1da177e2005-04-16 15:20:36 -070067
68 struct block_device *b_bdev;
69 bh_end_io_t *b_end_io; /* I/O completion */
70 void *b_private; /* reserved for b_end_io */
71 struct list_head b_assoc_buffers; /* associated with another mapping */
Jan Kara58ff4072006-10-17 00:10:19 -070072 struct address_space *b_assoc_map; /* mapping this buffer is
73 associated with */
Badari Pulavarty205f87f2006-03-26 01:38:00 -080074 atomic_t b_count; /* users using this buffer_head */
Linus Torvalds1da177e2005-04-16 15:20:36 -070075};
76
77/*
78 * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
79 * and buffer_foo() functions.
80 */
81#define BUFFER_FNS(bit, name) \
82static inline void set_buffer_##name(struct buffer_head *bh) \
83{ \
84 set_bit(BH_##bit, &(bh)->b_state); \
85} \
86static inline void clear_buffer_##name(struct buffer_head *bh) \
87{ \
88 clear_bit(BH_##bit, &(bh)->b_state); \
89} \
90static inline int buffer_##name(const struct buffer_head *bh) \
91{ \
92 return test_bit(BH_##bit, &(bh)->b_state); \
93}
94
95/*
96 * test_set_buffer_foo() and test_clear_buffer_foo()
97 */
98#define TAS_BUFFER_FNS(bit, name) \
99static inline int test_set_buffer_##name(struct buffer_head *bh) \
100{ \
101 return test_and_set_bit(BH_##bit, &(bh)->b_state); \
102} \
103static inline int test_clear_buffer_##name(struct buffer_head *bh) \
104{ \
105 return test_and_clear_bit(BH_##bit, &(bh)->b_state); \
106} \
107
108/*
109 * Emit the buffer bitops functions. Note that there are also functions
110 * of the form "mark_buffer_foo()". These are higher-level functions which
111 * do something in addition to setting a b_state bit.
112 */
113BUFFER_FNS(Uptodate, uptodate)
114BUFFER_FNS(Dirty, dirty)
115TAS_BUFFER_FNS(Dirty, dirty)
116BUFFER_FNS(Lock, locked)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117BUFFER_FNS(Req, req)
118TAS_BUFFER_FNS(Req, req)
119BUFFER_FNS(Mapped, mapped)
120BUFFER_FNS(New, new)
121BUFFER_FNS(Async_Read, async_read)
122BUFFER_FNS(Async_Write, async_write)
123BUFFER_FNS(Delay, delay)
124BUFFER_FNS(Boundary, boundary)
125BUFFER_FNS(Write_EIO, write_io_error)
David Chinner33a266d2007-02-12 00:51:41 -0800126BUFFER_FNS(Unwritten, unwritten)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127
128#define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK)
129#define touch_buffer(bh) mark_page_accessed(bh->b_page)
130
131/* If we *know* page->private refers to buffer_heads */
132#define page_buffers(page) \
133 ({ \
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700134 BUG_ON(!PagePrivate(page)); \
135 ((struct buffer_head *)page_private(page)); \
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136 })
137#define page_has_buffers(page) PagePrivate(page)
138
139/*
140 * Declarations
141 */
142
Harvey Harrisonb3c97522008-02-13 15:03:15 -0800143void mark_buffer_dirty(struct buffer_head *bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144void init_buffer(struct buffer_head *, bh_end_io_t *, void *);
145void set_bh_page(struct buffer_head *bh,
146 struct page *page, unsigned long offset);
147int try_to_free_buffers(struct page *);
148struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
149 int retry);
150void create_empty_buffers(struct page *, unsigned long,
151 unsigned long b_state);
152void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
153void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
Chris Mason35c80d52009-04-15 13:22:38 -0400154void end_buffer_async_write(struct buffer_head *bh, int uptodate);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155
156/* Things to do with buffers at mapping->private_list */
157void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
158int inode_has_buffers(struct inode *);
159void invalidate_inode_buffers(struct inode *);
160int remove_inode_buffers(struct inode *inode);
161int sync_mapping_buffers(struct address_space *mapping);
162void unmap_underlying_metadata(struct block_device *bdev, sector_t block);
163
164void mark_buffer_async_write(struct buffer_head *bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165void __wait_on_buffer(struct buffer_head *);
166wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -0800167struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block,
168 unsigned size);
169struct buffer_head *__getblk(struct block_device *bdev, sector_t block,
170 unsigned size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171void __brelse(struct buffer_head *);
172void __bforget(struct buffer_head *);
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -0800173void __breadahead(struct block_device *, sector_t block, unsigned int size);
174struct buffer_head *__bread(struct block_device *, sector_t block, unsigned size);
Peter Zijlstraf9a14392007-05-06 14:49:55 -0700175void invalidate_bh_lrus(void);
Al Virodd0fc662005-10-07 07:46:04 +0100176struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177void free_buffer_head(struct buffer_head * bh);
Harvey Harrisonb3c97522008-02-13 15:03:15 -0800178void unlock_buffer(struct buffer_head *bh);
179void __lock_buffer(struct buffer_head *bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180void ll_rw_block(int, int, struct buffer_head * bh[]);
181int sync_dirty_buffer(struct buffer_head *bh);
Christoph Hellwig87e99512010-08-11 17:05:45 +0200182int __sync_dirty_buffer(struct buffer_head *bh, int rw);
Christoph Hellwig9cb569d2010-08-11 17:06:24 +0200183void write_dirty_buffer(struct buffer_head *bh, int rw);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184int submit_bh(int, struct buffer_head *);
185void write_boundary_block(struct block_device *bdev,
186 sector_t bblock, unsigned blocksize);
Aneesh Kumar K.V389d1b02008-01-28 23:58:26 -0500187int bh_uptodate_or_lock(struct buffer_head *bh);
188int bh_submit_read(struct buffer_head *bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189
190extern int buffer_heads_over_limit;
191
192/*
193 * Generic address_space_operations implementations for buffer_head-backed
194 * address_spaces.
195 */
NeilBrown2ff28e22006-03-26 01:37:18 -0800196void block_invalidatepage(struct page *page, unsigned long offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197int block_write_full_page(struct page *page, get_block_t *get_block,
198 struct writeback_control *wbc);
Chris Mason35c80d52009-04-15 13:22:38 -0400199int block_write_full_page_endio(struct page *page, get_block_t *get_block,
200 struct writeback_control *wbc, bh_end_io_t *handler);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201int block_read_full_page(struct page*, get_block_t*);
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -0700202int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc,
203 unsigned long from);
Christoph Hellwig155130a2010-06-04 11:29:58 +0200204int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
205 unsigned flags, struct page **pagep, get_block_t *get_block);
Christoph Hellwig6e1db882010-06-04 11:29:57 +0200206int __block_write_begin(struct page *page, loff_t pos, unsigned len,
207 get_block_t *get_block);
Nick Pigginafddba42007-10-16 01:25:01 -0700208int block_write_end(struct file *, struct address_space *,
209 loff_t, unsigned, unsigned,
210 struct page *, void *);
211int generic_write_end(struct file *, struct address_space *,
212 loff_t, unsigned, unsigned,
213 struct page *, void *);
214void page_zero_new_buffers(struct page *page, unsigned from, unsigned to);
Nick Piggin89e10782007-10-16 01:25:07 -0700215int cont_write_begin(struct file *, struct address_space *, loff_t,
216 unsigned, unsigned, struct page **, void **,
217 get_block_t *, loff_t *);
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -0800218int generic_cont_expand_simple(struct inode *inode, loff_t size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219int block_commit_write(struct page *page, unsigned from, unsigned to);
Nick Pigginc2ec1752009-03-31 15:23:21 -0700220int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
David Chinner54171692007-07-19 17:39:55 +1000221 get_block_t get_block);
NeilBrown3978d7172006-03-26 01:37:17 -0800222void block_sync_page(struct page *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224int block_truncate_page(struct address_space *, loff_t, get_block_t *);
Christoph Hellwigea0f04e2010-06-04 11:29:54 +0200225int nobh_write_begin(struct address_space *, loff_t, unsigned, unsigned,
Nick Piggin03158cd2007-10-16 01:25:25 -0700226 struct page **, void **, get_block_t*);
227int nobh_write_end(struct file *, struct address_space *,
228 loff_t, unsigned, unsigned,
229 struct page *, void *);
230int nobh_truncate_page(struct address_space *, loff_t, get_block_t *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231int nobh_writepage(struct page *page, get_block_t *get_block,
232 struct writeback_control *wbc);
233
Adrian Bunkb6cd0b72006-06-27 02:53:54 -0700234void buffer_init(void);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235
236/*
237 * inline definitions
238 */
239
240static inline void attach_page_buffers(struct page *page,
241 struct buffer_head *head)
242{
243 page_cache_get(page);
244 SetPagePrivate(page);
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700245 set_page_private(page, (unsigned long)head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246}
247
248static inline void get_bh(struct buffer_head *bh)
249{
250 atomic_inc(&bh->b_count);
251}
252
253static inline void put_bh(struct buffer_head *bh)
254{
255 smp_mb__before_atomic_dec();
256 atomic_dec(&bh->b_count);
257}
258
259static inline void brelse(struct buffer_head *bh)
260{
261 if (bh)
262 __brelse(bh);
263}
264
265static inline void bforget(struct buffer_head *bh)
266{
267 if (bh)
268 __bforget(bh);
269}
270
271static inline struct buffer_head *
272sb_bread(struct super_block *sb, sector_t block)
273{
274 return __bread(sb->s_bdev, block, sb->s_blocksize);
275}
276
277static inline void
278sb_breadahead(struct super_block *sb, sector_t block)
279{
280 __breadahead(sb->s_bdev, block, sb->s_blocksize);
281}
282
283static inline struct buffer_head *
284sb_getblk(struct super_block *sb, sector_t block)
285{
286 return __getblk(sb->s_bdev, block, sb->s_blocksize);
287}
288
289static inline struct buffer_head *
290sb_find_get_block(struct super_block *sb, sector_t block)
291{
292 return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
293}
294
295static inline void
296map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
297{
298 set_buffer_mapped(bh);
299 bh->b_bdev = sb->s_bdev;
300 bh->b_blocknr = block;
Badari Pulavartyb0cf2322006-03-26 01:38:00 -0800301 bh->b_size = sb->s_blocksize;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302}
303
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304static inline void wait_on_buffer(struct buffer_head *bh)
305{
306 might_sleep();
Richard Kennedya9877cc2010-08-09 17:18:42 -0700307 if (buffer_locked(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308 __wait_on_buffer(bh);
309}
310
Nick Pigginca5de402008-08-02 12:02:13 +0200311static inline int trylock_buffer(struct buffer_head *bh)
312{
Nick Piggin51b07fc2008-10-18 20:27:00 -0700313 return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));
Nick Pigginca5de402008-08-02 12:02:13 +0200314}
315
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316static inline void lock_buffer(struct buffer_head *bh)
317{
318 might_sleep();
Nick Pigginca5de402008-08-02 12:02:13 +0200319 if (!trylock_buffer(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320 __lock_buffer(bh);
321}
322
David Howellscf9a2ae2006-08-29 19:05:54 +0100323extern int __set_page_dirty_buffers(struct page *page);
David Howells93614012006-09-30 20:45:40 +0200324
325#else /* CONFIG_BLOCK */
326
327static inline void buffer_init(void) {}
328static inline int try_to_free_buffers(struct page *page) { return 1; }
David Howells93614012006-09-30 20:45:40 +0200329static inline int inode_has_buffers(struct inode *inode) { return 0; }
330static inline void invalidate_inode_buffers(struct inode *inode) {}
331static inline int remove_inode_buffers(struct inode *inode) { return 1; }
332static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
David Howells93614012006-09-30 20:45:40 +0200333
334#endif /* CONFIG_BLOCK */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335#endif /* _LINUX_BUFFER_HEAD_H */