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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>
Arun Sharma600634972011-07-26 16:09:06 -070015#include <linux/atomic.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070016
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 */
Theodore Ts'o877f9622013-04-20 19:58:37 -040037 BH_Meta, /* Buffer contains metadata */
38 BH_Prio, /* Buffer should be submitted with REQ_PRIO */
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)
David Chinner33a266d2007-02-12 00:51:41 -0800128BUFFER_FNS(Unwritten, unwritten)
Theodore Ts'o877f9622013-04-20 19:58:37 -0400129BUFFER_FNS(Meta, meta)
130BUFFER_FNS(Prio, prio)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131
132#define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133
134/* If we *know* page->private refers to buffer_heads */
135#define page_buffers(page) \
136 ({ \
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700137 BUG_ON(!PagePrivate(page)); \
138 ((struct buffer_head *)page_private(page)); \
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139 })
140#define page_has_buffers(page) PagePrivate(page)
141
142/*
143 * Declarations
144 */
145
Harvey Harrisonb3c97522008-02-13 15:03:15 -0800146void mark_buffer_dirty(struct buffer_head *bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147void init_buffer(struct buffer_head *, bh_end_io_t *, void *);
Tejun Heof0059af2013-01-11 13:06:35 -0800148void touch_buffer(struct buffer_head *bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149void 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);
Christoph Hellwig87e99512010-08-11 17:05:45 +0200186int __sync_dirty_buffer(struct buffer_head *bh, int rw);
Christoph Hellwig9cb569d2010-08-11 17:06:24 +0200187void write_dirty_buffer(struct buffer_head *bh, int rw);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188int submit_bh(int, struct buffer_head *);
189void write_boundary_block(struct block_device *bdev,
190 sector_t bblock, unsigned blocksize);
Aneesh Kumar K.V389d1b02008-01-28 23:58:26 -0500191int bh_uptodate_or_lock(struct buffer_head *bh);
192int bh_submit_read(struct buffer_head *bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193
194extern int buffer_heads_over_limit;
195
196/*
197 * Generic address_space_operations implementations for buffer_head-backed
198 * address_spaces.
199 */
NeilBrown2ff28e22006-03-26 01:37:18 -0800200void block_invalidatepage(struct page *page, unsigned long offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201int block_write_full_page(struct page *page, get_block_t *get_block,
202 struct writeback_control *wbc);
Chris Mason35c80d52009-04-15 13:22:38 -0400203int block_write_full_page_endio(struct page *page, get_block_t *get_block,
204 struct writeback_control *wbc, bh_end_io_t *handler);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205int block_read_full_page(struct page*, get_block_t*);
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -0700206int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc,
207 unsigned long from);
Christoph Hellwig155130a2010-06-04 11:29:58 +0200208int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
209 unsigned flags, struct page **pagep, get_block_t *get_block);
Christoph Hellwig6e1db882010-06-04 11:29:57 +0200210int __block_write_begin(struct page *page, loff_t pos, unsigned len,
211 get_block_t *get_block);
Nick Pigginafddba42007-10-16 01:25:01 -0700212int block_write_end(struct file *, struct address_space *,
213 loff_t, unsigned, unsigned,
214 struct page *, void *);
215int generic_write_end(struct file *, struct address_space *,
216 loff_t, unsigned, unsigned,
217 struct page *, void *);
218void page_zero_new_buffers(struct page *page, unsigned from, unsigned to);
Nick Piggin89e10782007-10-16 01:25:07 -0700219int cont_write_begin(struct file *, struct address_space *, loff_t,
220 unsigned, unsigned, struct page **, void **,
221 get_block_t *, loff_t *);
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -0800222int generic_cont_expand_simple(struct inode *inode, loff_t size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223int block_commit_write(struct page *page, unsigned from, unsigned to);
Jan Kara24da4fa2011-05-24 00:23:34 +0200224int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
225 get_block_t get_block);
Nick Pigginc2ec1752009-03-31 15:23:21 -0700226int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
David Chinner54171692007-07-19 17:39:55 +1000227 get_block_t get_block);
Jan Kara24da4fa2011-05-24 00:23:34 +0200228/* Convert errno to return value from ->page_mkwrite() call */
229static inline int block_page_mkwrite_return(int err)
230{
231 if (err == 0)
232 return VM_FAULT_LOCKED;
233 if (err == -EFAULT)
234 return VM_FAULT_NOPAGE;
235 if (err == -ENOMEM)
236 return VM_FAULT_OOM;
Jan Karaea13a862011-05-24 00:23:35 +0200237 if (err == -EAGAIN)
238 return VM_FAULT_RETRY;
Jan Kara24da4fa2011-05-24 00:23:34 +0200239 /* -ENOSPC, -EDQUOT, -EIO ... */
240 return VM_FAULT_SIGBUS;
241}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700243int block_truncate_page(struct address_space *, loff_t, get_block_t *);
Christoph Hellwigea0f04e2010-06-04 11:29:54 +0200244int nobh_write_begin(struct address_space *, loff_t, unsigned, unsigned,
Nick Piggin03158cd2007-10-16 01:25:25 -0700245 struct page **, void **, get_block_t*);
246int nobh_write_end(struct file *, struct address_space *,
247 loff_t, unsigned, unsigned,
248 struct page *, void *);
249int nobh_truncate_page(struct address_space *, loff_t, get_block_t *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250int nobh_writepage(struct page *page, get_block_t *get_block,
251 struct writeback_control *wbc);
252
Adrian Bunkb6cd0b72006-06-27 02:53:54 -0700253void buffer_init(void);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254
255/*
256 * inline definitions
257 */
258
259static inline void attach_page_buffers(struct page *page,
260 struct buffer_head *head)
261{
262 page_cache_get(page);
263 SetPagePrivate(page);
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700264 set_page_private(page, (unsigned long)head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265}
266
267static inline void get_bh(struct buffer_head *bh)
268{
269 atomic_inc(&bh->b_count);
270}
271
272static inline void put_bh(struct buffer_head *bh)
273{
274 smp_mb__before_atomic_dec();
275 atomic_dec(&bh->b_count);
276}
277
278static inline void brelse(struct buffer_head *bh)
279{
280 if (bh)
281 __brelse(bh);
282}
283
284static inline void bforget(struct buffer_head *bh)
285{
286 if (bh)
287 __bforget(bh);
288}
289
290static inline struct buffer_head *
291sb_bread(struct super_block *sb, sector_t block)
292{
293 return __bread(sb->s_bdev, block, sb->s_blocksize);
294}
295
296static inline void
297sb_breadahead(struct super_block *sb, sector_t block)
298{
299 __breadahead(sb->s_bdev, block, sb->s_blocksize);
300}
301
302static inline struct buffer_head *
303sb_getblk(struct super_block *sb, sector_t block)
304{
305 return __getblk(sb->s_bdev, block, sb->s_blocksize);
306}
307
308static inline struct buffer_head *
309sb_find_get_block(struct super_block *sb, sector_t block)
310{
311 return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
312}
313
314static inline void
315map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
316{
317 set_buffer_mapped(bh);
318 bh->b_bdev = sb->s_bdev;
319 bh->b_blocknr = block;
Badari Pulavartyb0cf2322006-03-26 01:38:00 -0800320 bh->b_size = sb->s_blocksize;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700321}
322
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323static inline void wait_on_buffer(struct buffer_head *bh)
324{
325 might_sleep();
Richard Kennedya9877cc2010-08-09 17:18:42 -0700326 if (buffer_locked(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700327 __wait_on_buffer(bh);
328}
329
Nick Pigginca5de402008-08-02 12:02:13 +0200330static inline int trylock_buffer(struct buffer_head *bh)
331{
Nick Piggin51b07fc2008-10-18 20:27:00 -0700332 return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));
Nick Pigginca5de402008-08-02 12:02:13 +0200333}
334
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335static inline void lock_buffer(struct buffer_head *bh)
336{
337 might_sleep();
Nick Pigginca5de402008-08-02 12:02:13 +0200338 if (!trylock_buffer(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339 __lock_buffer(bh);
340}
341
David Howellscf9a2ae2006-08-29 19:05:54 +0100342extern int __set_page_dirty_buffers(struct page *page);
David Howells93614012006-09-30 20:45:40 +0200343
344#else /* CONFIG_BLOCK */
345
346static inline void buffer_init(void) {}
347static inline int try_to_free_buffers(struct page *page) { return 1; }
David Howells93614012006-09-30 20:45:40 +0200348static inline int inode_has_buffers(struct inode *inode) { return 0; }
349static inline void invalidate_inode_buffers(struct inode *inode) {}
350static inline int remove_inode_buffers(struct inode *inode) { return 1; }
351static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
David Howells93614012006-09-30 20:45:40 +0200352
353#endif /* CONFIG_BLOCK */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354#endif /* _LINUX_BUFFER_HEAD_H */