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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 */
Christoph Hellwig7b7a8662013-09-04 15:04:39 +020039 BH_Defer_Completion, /* Defer AIO completion to workqueue */
Linus Torvalds1da177e2005-04-16 15:20:36 -070040
41 BH_PrivateStart,/* not a state bit, but the first bit available
42 * for private allocation by other entities
43 */
44};
45
46#define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512)
47
48struct page;
49struct buffer_head;
50struct address_space;
51typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
52
53/*
Badari Pulavarty205f87f2006-03-26 01:38:00 -080054 * Historically, a buffer_head was used to map a single block
55 * within a page, and of course as the unit of I/O through the
56 * filesystem and block layers. Nowadays the basic I/O unit
57 * is the bio, and buffer_heads are used for extracting block
58 * mappings (via a get_block_t call), for tracking state within
59 * a page (via a page_mapping) and for wrapping bio submission
60 * for backward compatibility reasons (e.g. submit_bh).
Linus Torvalds1da177e2005-04-16 15:20:36 -070061 */
62struct buffer_head {
Linus Torvalds1da177e2005-04-16 15:20:36 -070063 unsigned long b_state; /* buffer state bitmap (see above) */
64 struct buffer_head *b_this_page;/* circular list of page's buffers */
65 struct page *b_page; /* the page this bh is mapped to */
Linus Torvalds1da177e2005-04-16 15:20:36 -070066
Badari Pulavarty205f87f2006-03-26 01:38:00 -080067 sector_t b_blocknr; /* start block number */
68 size_t b_size; /* size of mapping */
69 char *b_data; /* pointer to data within the page */
Linus Torvalds1da177e2005-04-16 15:20:36 -070070
71 struct block_device *b_bdev;
72 bh_end_io_t *b_end_io; /* I/O completion */
73 void *b_private; /* reserved for b_end_io */
74 struct list_head b_assoc_buffers; /* associated with another mapping */
Jan Kara58ff4072006-10-17 00:10:19 -070075 struct address_space *b_assoc_map; /* mapping this buffer is
76 associated with */
Badari Pulavarty205f87f2006-03-26 01:38:00 -080077 atomic_t b_count; /* users using this buffer_head */
Linus Torvalds1da177e2005-04-16 15:20:36 -070078};
79
80/*
81 * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
82 * and buffer_foo() functions.
83 */
84#define BUFFER_FNS(bit, name) \
85static inline void set_buffer_##name(struct buffer_head *bh) \
86{ \
87 set_bit(BH_##bit, &(bh)->b_state); \
88} \
89static inline void clear_buffer_##name(struct buffer_head *bh) \
90{ \
91 clear_bit(BH_##bit, &(bh)->b_state); \
92} \
93static inline int buffer_##name(const struct buffer_head *bh) \
94{ \
95 return test_bit(BH_##bit, &(bh)->b_state); \
96}
97
98/*
99 * test_set_buffer_foo() and test_clear_buffer_foo()
100 */
101#define TAS_BUFFER_FNS(bit, name) \
102static inline int test_set_buffer_##name(struct buffer_head *bh) \
103{ \
104 return test_and_set_bit(BH_##bit, &(bh)->b_state); \
105} \
106static inline int test_clear_buffer_##name(struct buffer_head *bh) \
107{ \
108 return test_and_clear_bit(BH_##bit, &(bh)->b_state); \
109} \
110
111/*
112 * Emit the buffer bitops functions. Note that there are also functions
113 * of the form "mark_buffer_foo()". These are higher-level functions which
114 * do something in addition to setting a b_state bit.
115 */
116BUFFER_FNS(Uptodate, uptodate)
117BUFFER_FNS(Dirty, dirty)
118TAS_BUFFER_FNS(Dirty, dirty)
119BUFFER_FNS(Lock, locked)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120BUFFER_FNS(Req, req)
121TAS_BUFFER_FNS(Req, req)
122BUFFER_FNS(Mapped, mapped)
123BUFFER_FNS(New, new)
124BUFFER_FNS(Async_Read, async_read)
125BUFFER_FNS(Async_Write, async_write)
126BUFFER_FNS(Delay, delay)
127BUFFER_FNS(Boundary, boundary)
128BUFFER_FNS(Write_EIO, write_io_error)
David Chinner33a266d2007-02-12 00:51:41 -0800129BUFFER_FNS(Unwritten, unwritten)
Theodore Ts'o877f9622013-04-20 19:58:37 -0400130BUFFER_FNS(Meta, meta)
131BUFFER_FNS(Prio, prio)
Christoph Hellwig7b7a8662013-09-04 15:04:39 +0200132BUFFER_FNS(Defer_Completion, defer_completion)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133
134#define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135
136/* If we *know* page->private refers to buffer_heads */
137#define page_buffers(page) \
138 ({ \
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700139 BUG_ON(!PagePrivate(page)); \
140 ((struct buffer_head *)page_private(page)); \
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141 })
142#define page_has_buffers(page) PagePrivate(page)
143
Mel Gormanb4597222013-07-03 15:02:05 -0700144void buffer_check_dirty_writeback(struct page *page,
145 bool *dirty, bool *writeback);
146
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147/*
148 * Declarations
149 */
150
Harvey Harrisonb3c97522008-02-13 15:03:15 -0800151void mark_buffer_dirty(struct buffer_head *bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152void init_buffer(struct buffer_head *, bh_end_io_t *, void *);
Tejun Heof0059af2013-01-11 13:06:35 -0800153void touch_buffer(struct buffer_head *bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154void set_bh_page(struct buffer_head *bh,
155 struct page *page, unsigned long offset);
156int try_to_free_buffers(struct page *);
157struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
158 int retry);
159void create_empty_buffers(struct page *, unsigned long,
160 unsigned long b_state);
161void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
162void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
Chris Mason35c80d52009-04-15 13:22:38 -0400163void end_buffer_async_write(struct buffer_head *bh, int uptodate);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164
165/* Things to do with buffers at mapping->private_list */
166void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
167int inode_has_buffers(struct inode *);
168void invalidate_inode_buffers(struct inode *);
169int remove_inode_buffers(struct inode *inode);
170int sync_mapping_buffers(struct address_space *mapping);
171void unmap_underlying_metadata(struct block_device *bdev, sector_t block);
172
173void mark_buffer_async_write(struct buffer_head *bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174void __wait_on_buffer(struct buffer_head *);
175wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -0800176struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block,
177 unsigned size);
Gioh Kim3b5e6452014-09-04 22:04:42 -0400178struct buffer_head *__getblk_gfp(struct block_device *bdev, sector_t block,
179 unsigned size, gfp_t gfp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180void __brelse(struct buffer_head *);
181void __bforget(struct buffer_head *);
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -0800182void __breadahead(struct block_device *, sector_t block, unsigned int size);
Gioh Kim3b5e6452014-09-04 22:04:42 -0400183struct buffer_head *__bread_gfp(struct block_device *,
184 sector_t block, unsigned size, gfp_t gfp);
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);
Christoph Hellwig87e99512010-08-11 17:05:45 +0200192int __sync_dirty_buffer(struct buffer_head *bh, int rw);
Christoph Hellwig9cb569d2010-08-11 17:06:24 +0200193void write_dirty_buffer(struct buffer_head *bh, int rw);
Darrick J. Wong7136851112013-04-29 15:07:25 -0700194int _submit_bh(int rw, struct buffer_head *bh, unsigned long bio_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195int submit_bh(int, struct buffer_head *);
196void write_boundary_block(struct block_device *bdev,
197 sector_t bblock, unsigned blocksize);
Aneesh Kumar K.V389d1b02008-01-28 23:58:26 -0500198int bh_uptodate_or_lock(struct buffer_head *bh);
199int bh_submit_read(struct buffer_head *bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200
201extern int buffer_heads_over_limit;
202
203/*
204 * Generic address_space_operations implementations for buffer_head-backed
205 * address_spaces.
206 */
Lukas Czernerd47992f2013-05-21 23:17:23 -0400207void block_invalidatepage(struct page *page, unsigned int offset,
208 unsigned int length);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209int block_write_full_page(struct page *page, get_block_t *get_block,
210 struct writeback_control *wbc);
211int block_read_full_page(struct page*, get_block_t*);
Al Viroc186afb42014-02-02 21:16:54 -0500212int block_is_partially_uptodate(struct page *page, unsigned long from,
213 unsigned long count);
Christoph Hellwig155130a2010-06-04 11:29:58 +0200214int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
215 unsigned flags, struct page **pagep, get_block_t *get_block);
Christoph Hellwig6e1db882010-06-04 11:29:57 +0200216int __block_write_begin(struct page *page, loff_t pos, unsigned len,
217 get_block_t *get_block);
Nick Pigginafddba42007-10-16 01:25:01 -0700218int block_write_end(struct file *, struct address_space *,
219 loff_t, unsigned, unsigned,
220 struct page *, void *);
221int generic_write_end(struct file *, struct address_space *,
222 loff_t, unsigned, unsigned,
223 struct page *, void *);
224void page_zero_new_buffers(struct page *page, unsigned from, unsigned to);
Nick Piggin89e10782007-10-16 01:25:07 -0700225int cont_write_begin(struct file *, struct address_space *, loff_t,
226 unsigned, unsigned, struct page **, void **,
227 get_block_t *, loff_t *);
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -0800228int generic_cont_expand_simple(struct inode *inode, loff_t size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229int block_commit_write(struct page *page, unsigned from, unsigned to);
Nick Pigginc2ec1752009-03-31 15:23:21 -0700230int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
David Chinner54171692007-07-19 17:39:55 +1000231 get_block_t get_block);
Jan Kara24da4fa2011-05-24 00:23:34 +0200232/* Convert errno to return value from ->page_mkwrite() call */
233static inline int block_page_mkwrite_return(int err)
234{
235 if (err == 0)
236 return VM_FAULT_LOCKED;
237 if (err == -EFAULT)
238 return VM_FAULT_NOPAGE;
239 if (err == -ENOMEM)
240 return VM_FAULT_OOM;
Jan Karaea13a862011-05-24 00:23:35 +0200241 if (err == -EAGAIN)
242 return VM_FAULT_RETRY;
Jan Kara24da4fa2011-05-24 00:23:34 +0200243 /* -ENOSPC, -EDQUOT, -EIO ... */
244 return VM_FAULT_SIGBUS;
245}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247int block_truncate_page(struct address_space *, loff_t, get_block_t *);
Christoph Hellwigea0f04e2010-06-04 11:29:54 +0200248int nobh_write_begin(struct address_space *, loff_t, unsigned, unsigned,
Nick Piggin03158cd2007-10-16 01:25:25 -0700249 struct page **, void **, get_block_t*);
250int nobh_write_end(struct file *, struct address_space *,
251 loff_t, unsigned, unsigned,
252 struct page *, void *);
253int nobh_truncate_page(struct address_space *, loff_t, get_block_t *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254int nobh_writepage(struct page *page, get_block_t *get_block,
255 struct writeback_control *wbc);
256
Adrian Bunkb6cd0b72006-06-27 02:53:54 -0700257void buffer_init(void);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258
259/*
260 * inline definitions
261 */
262
263static inline void attach_page_buffers(struct page *page,
264 struct buffer_head *head)
265{
266 page_cache_get(page);
267 SetPagePrivate(page);
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700268 set_page_private(page, (unsigned long)head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269}
270
271static inline void get_bh(struct buffer_head *bh)
272{
273 atomic_inc(&bh->b_count);
274}
275
276static inline void put_bh(struct buffer_head *bh)
277{
Peter Zijlstra4e857c52014-03-17 18:06:10 +0100278 smp_mb__before_atomic();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279 atomic_dec(&bh->b_count);
280}
281
282static inline void brelse(struct buffer_head *bh)
283{
284 if (bh)
285 __brelse(bh);
286}
287
288static inline void bforget(struct buffer_head *bh)
289{
290 if (bh)
291 __bforget(bh);
292}
293
294static inline struct buffer_head *
295sb_bread(struct super_block *sb, sector_t block)
296{
Gioh Kim3b5e6452014-09-04 22:04:42 -0400297 return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
298}
299
300static inline struct buffer_head *
301sb_bread_unmovable(struct super_block *sb, sector_t block)
302{
303 return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304}
305
306static inline void
307sb_breadahead(struct super_block *sb, sector_t block)
308{
309 __breadahead(sb->s_bdev, block, sb->s_blocksize);
310}
311
312static inline struct buffer_head *
313sb_getblk(struct super_block *sb, sector_t block)
314{
Gioh Kim3b5e6452014-09-04 22:04:42 -0400315 return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316}
317
Nikolay Borisovbd7ade32015-07-02 01:32:44 -0400318
319static inline struct buffer_head *
320sb_getblk_gfp(struct super_block *sb, sector_t block, gfp_t gfp)
321{
322 return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, gfp);
323}
324
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325static inline struct buffer_head *
326sb_find_get_block(struct super_block *sb, sector_t block)
327{
328 return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
329}
330
331static inline void
332map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
333{
334 set_buffer_mapped(bh);
335 bh->b_bdev = sb->s_bdev;
336 bh->b_blocknr = block;
Badari Pulavartyb0cf2322006-03-26 01:38:00 -0800337 bh->b_size = sb->s_blocksize;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338}
339
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340static inline void wait_on_buffer(struct buffer_head *bh)
341{
342 might_sleep();
Richard Kennedya9877cc2010-08-09 17:18:42 -0700343 if (buffer_locked(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344 __wait_on_buffer(bh);
345}
346
Nick Pigginca5de402008-08-02 12:02:13 +0200347static inline int trylock_buffer(struct buffer_head *bh)
348{
Nick Piggin51b07fc2008-10-18 20:27:00 -0700349 return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));
Nick Pigginca5de402008-08-02 12:02:13 +0200350}
351
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352static inline void lock_buffer(struct buffer_head *bh)
353{
354 might_sleep();
Nick Pigginca5de402008-08-02 12:02:13 +0200355 if (!trylock_buffer(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356 __lock_buffer(bh);
357}
358
Gioh Kim3b5e6452014-09-04 22:04:42 -0400359static inline struct buffer_head *getblk_unmovable(struct block_device *bdev,
360 sector_t block,
361 unsigned size)
362{
363 return __getblk_gfp(bdev, block, size, 0);
364}
365
366static inline struct buffer_head *__getblk(struct block_device *bdev,
367 sector_t block,
368 unsigned size)
369{
370 return __getblk_gfp(bdev, block, size, __GFP_MOVABLE);
371}
372
373/**
374 * __bread() - reads a specified block and returns the bh
375 * @bdev: the block_device to read from
376 * @block: number of block
377 * @size: size (in bytes) to read
378 *
379 * Reads a specified block, and returns buffer head that contains it.
380 * The page cache is allocated from movable area so that it can be migrated.
381 * It returns NULL if the block was unreadable.
382 */
383static inline struct buffer_head *
384__bread(struct block_device *bdev, sector_t block, unsigned size)
385{
386 return __bread_gfp(bdev, block, size, __GFP_MOVABLE);
387}
388
David Howellscf9a2ae2006-08-29 19:05:54 +0100389extern int __set_page_dirty_buffers(struct page *page);
David Howells93614012006-09-30 20:45:40 +0200390
391#else /* CONFIG_BLOCK */
392
393static inline void buffer_init(void) {}
394static inline int try_to_free_buffers(struct page *page) { return 1; }
David Howells93614012006-09-30 20:45:40 +0200395static inline int inode_has_buffers(struct inode *inode) { return 0; }
396static inline void invalidate_inode_buffers(struct inode *inode) {}
397static inline int remove_inode_buffers(struct inode *inode) { return 1; }
398static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
David Howells93614012006-09-30 20:45:40 +0200399
400#endif /* CONFIG_BLOCK */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700401#endif /* _LINUX_BUFFER_HEAD_H */