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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * include/linux/buffer_head.h
4 *
5 * Everything to do with buffer_heads.
6 */
7
8#ifndef _LINUX_BUFFER_HEAD_H
9#define _LINUX_BUFFER_HEAD_H
10
11#include <linux/types.h>
12#include <linux/fs.h>
13#include <linux/linkage.h>
14#include <linux/pagemap.h>
15#include <linux/wait.h>
16#include <linux/atomic.h>
17
18#ifdef CONFIG_BLOCK
19
20enum bh_state_bits {
21 BH_Uptodate, /* Contains valid data */
22 BH_Dirty, /* Is dirty */
23 BH_Lock, /* Is locked */
24 BH_Req, /* Has been submitted for I/O */
25
26 BH_Mapped, /* Has a disk mapping */
27 BH_New, /* Disk mapping was newly created by get_block */
28 BH_Async_Read, /* Is under end_buffer_async_read I/O */
29 BH_Async_Write, /* Is under end_buffer_async_write I/O */
30 BH_Delay, /* Buffer is not yet allocated on disk */
31 BH_Boundary, /* Block is followed by a discontiguity */
32 BH_Write_EIO, /* I/O error on write */
33 BH_Unwritten, /* Buffer is allocated on disk but not written */
34 BH_Quiet, /* Buffer Error Prinks to be quiet */
35 BH_Meta, /* Buffer contains metadata */
36 BH_Prio, /* Buffer should be submitted with REQ_PRIO */
37 BH_Defer_Completion, /* Defer AIO completion to workqueue */
38
39 BH_PrivateStart,/* not a state bit, but the first bit available
40 * for private allocation by other entities
41 */
42};
43
44#define MAX_BUF_PER_PAGE (PAGE_SIZE / 512)
45
46struct page;
47struct buffer_head;
48struct address_space;
49typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
50
51/*
52 * Historically, a buffer_head was used to map a single block
53 * within a page, and of course as the unit of I/O through the
54 * filesystem and block layers. Nowadays the basic I/O unit
55 * is the bio, and buffer_heads are used for extracting block
56 * mappings (via a get_block_t call), for tracking state within
57 * a page (via a page_mapping) and for wrapping bio submission
58 * for backward compatibility reasons (e.g. submit_bh).
59 */
60struct buffer_head {
61 unsigned long b_state; /* buffer state bitmap (see above) */
62 struct buffer_head *b_this_page;/* circular list of page's buffers */
63 struct page *b_page; /* the page this bh is mapped to */
64
65 sector_t b_blocknr; /* start block number */
66 size_t b_size; /* size of mapping */
67 char *b_data; /* pointer to data within the page */
68
69 struct block_device *b_bdev;
70 bh_end_io_t *b_end_io; /* I/O completion */
71 void *b_private; /* reserved for b_end_io */
72 struct list_head b_assoc_buffers; /* associated with another mapping */
73 struct address_space *b_assoc_map; /* mapping this buffer is
74 associated with */
75 atomic_t b_count; /* users using this buffer_head */
76 spinlock_t b_uptodate_lock; /* Used by the first bh in a page, to
77 * serialise IO completion of other
78 * buffers in the page */
79};
80
81/*
82 * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
83 * and buffer_foo() functions.
84 * To avoid reset buffer flags that are already set, because that causes
85 * a costly cache line transition, check the flag first.
86 */
87#define BUFFER_FNS(bit, name) \
88static __always_inline void set_buffer_##name(struct buffer_head *bh) \
89{ \
90 if (!test_bit(BH_##bit, &(bh)->b_state)) \
91 set_bit(BH_##bit, &(bh)->b_state); \
92} \
93static __always_inline void clear_buffer_##name(struct buffer_head *bh) \
94{ \
95 clear_bit(BH_##bit, &(bh)->b_state); \
96} \
97static __always_inline int buffer_##name(const struct buffer_head *bh) \
98{ \
99 return test_bit(BH_##bit, &(bh)->b_state); \
100}
101
102/*
103 * test_set_buffer_foo() and test_clear_buffer_foo()
104 */
105#define TAS_BUFFER_FNS(bit, name) \
106static __always_inline int test_set_buffer_##name(struct buffer_head *bh) \
107{ \
108 return test_and_set_bit(BH_##bit, &(bh)->b_state); \
109} \
110static __always_inline int test_clear_buffer_##name(struct buffer_head *bh) \
111{ \
112 return test_and_clear_bit(BH_##bit, &(bh)->b_state); \
113} \
114
115/*
116 * Emit the buffer bitops functions. Note that there are also functions
117 * of the form "mark_buffer_foo()". These are higher-level functions which
118 * do something in addition to setting a b_state bit.
119 */
120BUFFER_FNS(Uptodate, uptodate)
121BUFFER_FNS(Dirty, dirty)
122TAS_BUFFER_FNS(Dirty, dirty)
123BUFFER_FNS(Lock, locked)
124BUFFER_FNS(Req, req)
125TAS_BUFFER_FNS(Req, req)
126BUFFER_FNS(Mapped, mapped)
127BUFFER_FNS(New, new)
128BUFFER_FNS(Async_Read, async_read)
129BUFFER_FNS(Async_Write, async_write)
130BUFFER_FNS(Delay, delay)
131BUFFER_FNS(Boundary, boundary)
132BUFFER_FNS(Write_EIO, write_io_error)
133BUFFER_FNS(Unwritten, unwritten)
134BUFFER_FNS(Meta, meta)
135BUFFER_FNS(Prio, prio)
136BUFFER_FNS(Defer_Completion, defer_completion)
137
138#define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK)
139
140/* If we *know* page->private refers to buffer_heads */
141#define page_buffers(page) \
142 ({ \
143 BUG_ON(!PagePrivate(page)); \
144 ((struct buffer_head *)page_private(page)); \
145 })
146#define page_has_buffers(page) PagePrivate(page)
147
148void buffer_check_dirty_writeback(struct page *page,
149 bool *dirty, bool *writeback);
150
151/*
152 * Declarations
153 */
154
155void mark_buffer_dirty(struct buffer_head *bh);
156void mark_buffer_write_io_error(struct buffer_head *bh);
157void touch_buffer(struct buffer_head *bh);
158void set_bh_page(struct buffer_head *bh,
159 struct page *page, unsigned long offset);
160int try_to_free_buffers(struct page *);
161struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
162 bool retry);
163void create_empty_buffers(struct page *, unsigned long,
164 unsigned long b_state);
165void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
166void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
167void end_buffer_async_write(struct buffer_head *bh, int uptodate);
168
169/* Things to do with buffers at mapping->private_list */
170void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
171int inode_has_buffers(struct inode *);
172void invalidate_inode_buffers(struct inode *);
173int remove_inode_buffers(struct inode *inode);
174int sync_mapping_buffers(struct address_space *mapping);
175void clean_bdev_aliases(struct block_device *bdev, sector_t block,
176 sector_t len);
177static inline void clean_bdev_bh_alias(struct buffer_head *bh)
178{
179 clean_bdev_aliases(bh->b_bdev, bh->b_blocknr, 1);
180}
181
182void mark_buffer_async_write(struct buffer_head *bh);
183void __wait_on_buffer(struct buffer_head *);
184wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
185struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block,
186 unsigned size);
187struct buffer_head *__getblk_gfp(struct block_device *bdev, sector_t block,
188 unsigned size, gfp_t gfp);
189void __brelse(struct buffer_head *);
190void __bforget(struct buffer_head *);
191void __breadahead(struct block_device *, sector_t block, unsigned int size);
192void __breadahead_gfp(struct block_device *, sector_t block, unsigned int size,
193 gfp_t gfp);
194struct buffer_head *__bread_gfp(struct block_device *,
195 sector_t block, unsigned size, gfp_t gfp);
196void invalidate_bh_lrus(void);
197struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
198void free_buffer_head(struct buffer_head * bh);
199void unlock_buffer(struct buffer_head *bh);
200void __lock_buffer(struct buffer_head *bh);
201void ll_rw_block(int, int, int, struct buffer_head * bh[]);
202int sync_dirty_buffer(struct buffer_head *bh);
203int __sync_dirty_buffer(struct buffer_head *bh, int op_flags);
204void write_dirty_buffer(struct buffer_head *bh, int op_flags);
205int submit_bh(int, int, struct buffer_head *);
206void write_boundary_block(struct block_device *bdev,
207 sector_t bblock, unsigned blocksize);
208int bh_uptodate_or_lock(struct buffer_head *bh);
209int bh_submit_read(struct buffer_head *bh);
210
211extern int buffer_heads_over_limit;
212
213/*
214 * Generic address_space_operations implementations for buffer_head-backed
215 * address_spaces.
216 */
217void block_invalidatepage(struct page *page, unsigned int offset,
218 unsigned int length);
219int block_write_full_page(struct page *page, get_block_t *get_block,
220 struct writeback_control *wbc);
221int __block_write_full_page(struct inode *inode, struct page *page,
222 get_block_t *get_block, struct writeback_control *wbc,
223 bh_end_io_t *handler);
224int block_read_full_page(struct page*, get_block_t*);
225int block_is_partially_uptodate(struct page *page, unsigned long from,
226 unsigned long count);
227int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
228 unsigned flags, struct page **pagep, get_block_t *get_block);
229int __block_write_begin(struct page *page, loff_t pos, unsigned len,
230 get_block_t *get_block);
231int block_write_end(struct file *, struct address_space *,
232 loff_t, unsigned, unsigned,
233 struct page *, void *);
234int generic_write_end(struct file *, struct address_space *,
235 loff_t, unsigned, unsigned,
236 struct page *, void *);
237void page_zero_new_buffers(struct page *page, unsigned from, unsigned to);
238void clean_page_buffers(struct page *page);
239int cont_write_begin(struct file *, struct address_space *, loff_t,
240 unsigned, unsigned, struct page **, void **,
241 get_block_t *, loff_t *);
242int generic_cont_expand_simple(struct inode *inode, loff_t size);
243int block_commit_write(struct page *page, unsigned from, unsigned to);
244int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
245 get_block_t get_block);
246/* Convert errno to return value from ->page_mkwrite() call */
247static inline vm_fault_t block_page_mkwrite_return(int err)
248{
249 if (err == 0)
250 return VM_FAULT_LOCKED;
251 if (err == -EFAULT || err == -EAGAIN)
252 return VM_FAULT_NOPAGE;
253 if (err == -ENOMEM)
254 return VM_FAULT_OOM;
255 /* -ENOSPC, -EDQUOT, -EIO ... */
256 return VM_FAULT_SIGBUS;
257}
258sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
259int block_truncate_page(struct address_space *, loff_t, get_block_t *);
260int nobh_write_begin(struct address_space *, loff_t, unsigned, unsigned,
261 struct page **, void **, get_block_t*);
262int nobh_write_end(struct file *, struct address_space *,
263 loff_t, unsigned, unsigned,
264 struct page *, void *);
265int nobh_truncate_page(struct address_space *, loff_t, get_block_t *);
266int nobh_writepage(struct page *page, get_block_t *get_block,
267 struct writeback_control *wbc);
268
269void buffer_init(void);
270
271/*
272 * inline definitions
273 */
274
275static inline void get_bh(struct buffer_head *bh)
276{
277 atomic_inc(&bh->b_count);
278}
279
280static inline void put_bh(struct buffer_head *bh)
281{
282 smp_mb__before_atomic();
283 atomic_dec(&bh->b_count);
284}
285
286static inline void brelse(struct buffer_head *bh)
287{
288 if (bh)
289 __brelse(bh);
290}
291
292static inline void bforget(struct buffer_head *bh)
293{
294 if (bh)
295 __bforget(bh);
296}
297
298static inline struct buffer_head *
299sb_bread(struct super_block *sb, sector_t block)
300{
301 return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
302}
303
304static inline struct buffer_head *
305sb_bread_unmovable(struct super_block *sb, sector_t block)
306{
307 return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, 0);
308}
309
310static inline void
311sb_breadahead(struct super_block *sb, sector_t block)
312{
313 __breadahead(sb->s_bdev, block, sb->s_blocksize);
314}
315
316static inline void
317sb_breadahead_unmovable(struct super_block *sb, sector_t block)
318{
319 __breadahead_gfp(sb->s_bdev, block, sb->s_blocksize, 0);
320}
321
322static inline struct buffer_head *
323sb_getblk(struct super_block *sb, sector_t block)
324{
325 return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
326}
327
328
329static inline struct buffer_head *
330sb_getblk_gfp(struct super_block *sb, sector_t block, gfp_t gfp)
331{
332 return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, gfp);
333}
334
335static inline struct buffer_head *
336sb_find_get_block(struct super_block *sb, sector_t block)
337{
338 return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
339}
340
341static inline void
342map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
343{
344 set_buffer_mapped(bh);
345 bh->b_bdev = sb->s_bdev;
346 bh->b_blocknr = block;
347 bh->b_size = sb->s_blocksize;
348}
349
350static inline void wait_on_buffer(struct buffer_head *bh)
351{
352 might_sleep();
353 if (buffer_locked(bh))
354 __wait_on_buffer(bh);
355}
356
357static inline int trylock_buffer(struct buffer_head *bh)
358{
359 return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));
360}
361
362static inline void lock_buffer(struct buffer_head *bh)
363{
364 might_sleep();
365 if (!trylock_buffer(bh))
366 __lock_buffer(bh);
367}
368
369static inline struct buffer_head *getblk_unmovable(struct block_device *bdev,
370 sector_t block,
371 unsigned size)
372{
373 return __getblk_gfp(bdev, block, size, 0);
374}
375
376static inline struct buffer_head *__getblk(struct block_device *bdev,
377 sector_t block,
378 unsigned size)
379{
380 return __getblk_gfp(bdev, block, size, __GFP_MOVABLE);
381}
382
383/**
384 * __bread() - reads a specified block and returns the bh
385 * @bdev: the block_device to read from
386 * @block: number of block
387 * @size: size (in bytes) to read
388 *
389 * Reads a specified block, and returns buffer head that contains it.
390 * The page cache is allocated from movable area so that it can be migrated.
391 * It returns NULL if the block was unreadable.
392 */
393static inline struct buffer_head *
394__bread(struct block_device *bdev, sector_t block, unsigned size)
395{
396 return __bread_gfp(bdev, block, size, __GFP_MOVABLE);
397}
398
399extern int __set_page_dirty_buffers(struct page *page);
400
401#else /* CONFIG_BLOCK */
402
403static inline void buffer_init(void) {}
404static inline int try_to_free_buffers(struct page *page) { return 1; }
405static inline int inode_has_buffers(struct inode *inode) { return 0; }
406static inline void invalidate_inode_buffers(struct inode *inode) {}
407static inline int remove_inode_buffers(struct inode *inode) { return 1; }
408static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
409#define buffer_heads_over_limit 0
410
411#endif /* CONFIG_BLOCK */
412#endif /* _LINUX_BUFFER_HEAD_H */
1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * include/linux/buffer_head.h
4 *
5 * Everything to do with buffer_heads.
6 */
7
8#ifndef _LINUX_BUFFER_HEAD_H
9#define _LINUX_BUFFER_HEAD_H
10
11#include <linux/types.h>
12#include <linux/blk_types.h>
13#include <linux/fs.h>
14#include <linux/linkage.h>
15#include <linux/pagemap.h>
16#include <linux/wait.h>
17#include <linux/atomic.h>
18
19enum 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 */
24
25 BH_Mapped, /* Has a disk mapping */
26 BH_New, /* Disk mapping was newly created by get_block */
27 BH_Async_Read, /* Is under end_buffer_async_read I/O */
28 BH_Async_Write, /* Is under end_buffer_async_write I/O */
29 BH_Delay, /* Buffer is not yet allocated on disk */
30 BH_Boundary, /* Block is followed by a discontiguity */
31 BH_Write_EIO, /* I/O error on write */
32 BH_Unwritten, /* Buffer is allocated on disk but not written */
33 BH_Quiet, /* Buffer Error Prinks to be quiet */
34 BH_Meta, /* Buffer contains metadata */
35 BH_Prio, /* Buffer should be submitted with REQ_PRIO */
36 BH_Defer_Completion, /* Defer AIO completion to workqueue */
37
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_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/*
51 * 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).
58 */
59struct buffer_head {
60 unsigned long b_state; /* buffer state bitmap (see above) */
61 struct buffer_head *b_this_page;/* circular list of page's buffers */
62 union {
63 struct page *b_page; /* the page this bh is mapped to */
64 struct folio *b_folio; /* the folio this bh is mapped to */
65 };
66
67 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 */
70
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 */
75 struct address_space *b_assoc_map; /* mapping this buffer is
76 associated with */
77 atomic_t b_count; /* users using this buffer_head */
78 spinlock_t b_uptodate_lock; /* Used by the first bh in a page, to
79 * serialise IO completion of other
80 * buffers in the page */
81};
82
83/*
84 * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
85 * and buffer_foo() functions.
86 * To avoid reset buffer flags that are already set, because that causes
87 * a costly cache line transition, check the flag first.
88 */
89#define BUFFER_FNS(bit, name) \
90static __always_inline void set_buffer_##name(struct buffer_head *bh) \
91{ \
92 if (!test_bit(BH_##bit, &(bh)->b_state)) \
93 set_bit(BH_##bit, &(bh)->b_state); \
94} \
95static __always_inline void clear_buffer_##name(struct buffer_head *bh) \
96{ \
97 clear_bit(BH_##bit, &(bh)->b_state); \
98} \
99static __always_inline int buffer_##name(const struct buffer_head *bh) \
100{ \
101 return test_bit(BH_##bit, &(bh)->b_state); \
102}
103
104/*
105 * test_set_buffer_foo() and test_clear_buffer_foo()
106 */
107#define TAS_BUFFER_FNS(bit, name) \
108static __always_inline int test_set_buffer_##name(struct buffer_head *bh) \
109{ \
110 return test_and_set_bit(BH_##bit, &(bh)->b_state); \
111} \
112static __always_inline int test_clear_buffer_##name(struct buffer_head *bh) \
113{ \
114 return test_and_clear_bit(BH_##bit, &(bh)->b_state); \
115} \
116
117/*
118 * Emit the buffer bitops functions. Note that there are also functions
119 * of the form "mark_buffer_foo()". These are higher-level functions which
120 * do something in addition to setting a b_state bit.
121 */
122BUFFER_FNS(Dirty, dirty)
123TAS_BUFFER_FNS(Dirty, dirty)
124BUFFER_FNS(Lock, locked)
125BUFFER_FNS(Req, req)
126TAS_BUFFER_FNS(Req, req)
127BUFFER_FNS(Mapped, mapped)
128BUFFER_FNS(New, new)
129BUFFER_FNS(Async_Read, async_read)
130BUFFER_FNS(Async_Write, async_write)
131BUFFER_FNS(Delay, delay)
132BUFFER_FNS(Boundary, boundary)
133BUFFER_FNS(Write_EIO, write_io_error)
134BUFFER_FNS(Unwritten, unwritten)
135BUFFER_FNS(Meta, meta)
136BUFFER_FNS(Prio, prio)
137BUFFER_FNS(Defer_Completion, defer_completion)
138
139static __always_inline void set_buffer_uptodate(struct buffer_head *bh)
140{
141 /*
142 * If somebody else already set this uptodate, they will
143 * have done the memory barrier, and a reader will thus
144 * see *some* valid buffer state.
145 *
146 * Any other serialization (with IO errors or whatever that
147 * might clear the bit) has to come from other state (eg BH_Lock).
148 */
149 if (test_bit(BH_Uptodate, &bh->b_state))
150 return;
151
152 /*
153 * make it consistent with folio_mark_uptodate
154 * pairs with smp_load_acquire in buffer_uptodate
155 */
156 smp_mb__before_atomic();
157 set_bit(BH_Uptodate, &bh->b_state);
158}
159
160static __always_inline void clear_buffer_uptodate(struct buffer_head *bh)
161{
162 clear_bit(BH_Uptodate, &bh->b_state);
163}
164
165static __always_inline int buffer_uptodate(const struct buffer_head *bh)
166{
167 /*
168 * make it consistent with folio_test_uptodate
169 * pairs with smp_mb__before_atomic in set_buffer_uptodate
170 */
171 return test_bit_acquire(BH_Uptodate, &bh->b_state);
172}
173
174static inline unsigned long bh_offset(const struct buffer_head *bh)
175{
176 return (unsigned long)(bh)->b_data & (page_size(bh->b_page) - 1);
177}
178
179/* If we *know* page->private refers to buffer_heads */
180#define page_buffers(page) \
181 ({ \
182 BUG_ON(!PagePrivate(page)); \
183 ((struct buffer_head *)page_private(page)); \
184 })
185#define page_has_buffers(page) PagePrivate(page)
186#define folio_buffers(folio) folio_get_private(folio)
187
188void buffer_check_dirty_writeback(struct folio *folio,
189 bool *dirty, bool *writeback);
190
191/*
192 * Declarations
193 */
194
195void mark_buffer_dirty(struct buffer_head *bh);
196void mark_buffer_write_io_error(struct buffer_head *bh);
197void touch_buffer(struct buffer_head *bh);
198void folio_set_bh(struct buffer_head *bh, struct folio *folio,
199 unsigned long offset);
200struct buffer_head *folio_alloc_buffers(struct folio *folio, unsigned long size,
201 gfp_t gfp);
202struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
203 bool retry);
204struct buffer_head *create_empty_buffers(struct folio *folio,
205 unsigned long blocksize, unsigned long b_state);
206void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
207void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
208
209/* Things to do with buffers at mapping->private_list */
210void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
211int generic_buffers_fsync_noflush(struct file *file, loff_t start, loff_t end,
212 bool datasync);
213int generic_buffers_fsync(struct file *file, loff_t start, loff_t end,
214 bool datasync);
215void clean_bdev_aliases(struct block_device *bdev, sector_t block,
216 sector_t len);
217static inline void clean_bdev_bh_alias(struct buffer_head *bh)
218{
219 clean_bdev_aliases(bh->b_bdev, bh->b_blocknr, 1);
220}
221
222void mark_buffer_async_write(struct buffer_head *bh);
223void __wait_on_buffer(struct buffer_head *);
224wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
225struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block,
226 unsigned size);
227struct buffer_head *bdev_getblk(struct block_device *bdev, sector_t block,
228 unsigned size, gfp_t gfp);
229void __brelse(struct buffer_head *);
230void __bforget(struct buffer_head *);
231void __breadahead(struct block_device *, sector_t block, unsigned int size);
232struct buffer_head *__bread_gfp(struct block_device *,
233 sector_t block, unsigned size, gfp_t gfp);
234struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
235void free_buffer_head(struct buffer_head * bh);
236void unlock_buffer(struct buffer_head *bh);
237void __lock_buffer(struct buffer_head *bh);
238int sync_dirty_buffer(struct buffer_head *bh);
239int __sync_dirty_buffer(struct buffer_head *bh, blk_opf_t op_flags);
240void write_dirty_buffer(struct buffer_head *bh, blk_opf_t op_flags);
241void submit_bh(blk_opf_t, struct buffer_head *);
242void write_boundary_block(struct block_device *bdev,
243 sector_t bblock, unsigned blocksize);
244int bh_uptodate_or_lock(struct buffer_head *bh);
245int __bh_read(struct buffer_head *bh, blk_opf_t op_flags, bool wait);
246void __bh_read_batch(int nr, struct buffer_head *bhs[],
247 blk_opf_t op_flags, bool force_lock);
248
249/*
250 * Generic address_space_operations implementations for buffer_head-backed
251 * address_spaces.
252 */
253void block_invalidate_folio(struct folio *folio, size_t offset, size_t length);
254int block_write_full_folio(struct folio *folio, struct writeback_control *wbc,
255 void *get_block);
256int __block_write_full_folio(struct inode *inode, struct folio *folio,
257 get_block_t *get_block, struct writeback_control *wbc);
258int block_read_full_folio(struct folio *, get_block_t *);
259bool block_is_partially_uptodate(struct folio *, size_t from, size_t count);
260int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
261 struct page **pagep, get_block_t *get_block);
262int __block_write_begin(struct page *page, loff_t pos, unsigned len,
263 get_block_t *get_block);
264int block_write_end(struct file *, struct address_space *,
265 loff_t, unsigned, unsigned,
266 struct page *, void *);
267int generic_write_end(struct file *, struct address_space *,
268 loff_t, unsigned, unsigned,
269 struct page *, void *);
270void folio_zero_new_buffers(struct folio *folio, size_t from, size_t to);
271int cont_write_begin(struct file *, struct address_space *, loff_t,
272 unsigned, struct page **, void **,
273 get_block_t *, loff_t *);
274int generic_cont_expand_simple(struct inode *inode, loff_t size);
275void block_commit_write(struct page *page, unsigned int from, unsigned int to);
276int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
277 get_block_t get_block);
278sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
279int block_truncate_page(struct address_space *, loff_t, get_block_t *);
280
281#ifdef CONFIG_MIGRATION
282extern int buffer_migrate_folio(struct address_space *,
283 struct folio *dst, struct folio *src, enum migrate_mode);
284extern int buffer_migrate_folio_norefs(struct address_space *,
285 struct folio *dst, struct folio *src, enum migrate_mode);
286#else
287#define buffer_migrate_folio NULL
288#define buffer_migrate_folio_norefs NULL
289#endif
290
291/*
292 * inline definitions
293 */
294
295static inline void get_bh(struct buffer_head *bh)
296{
297 atomic_inc(&bh->b_count);
298}
299
300static inline void put_bh(struct buffer_head *bh)
301{
302 smp_mb__before_atomic();
303 atomic_dec(&bh->b_count);
304}
305
306static inline void brelse(struct buffer_head *bh)
307{
308 if (bh)
309 __brelse(bh);
310}
311
312static inline void bforget(struct buffer_head *bh)
313{
314 if (bh)
315 __bforget(bh);
316}
317
318static inline struct buffer_head *
319sb_bread(struct super_block *sb, sector_t block)
320{
321 return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
322}
323
324static inline struct buffer_head *
325sb_bread_unmovable(struct super_block *sb, sector_t block)
326{
327 return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, 0);
328}
329
330static inline void
331sb_breadahead(struct super_block *sb, sector_t block)
332{
333 __breadahead(sb->s_bdev, block, sb->s_blocksize);
334}
335
336static inline struct buffer_head *getblk_unmovable(struct block_device *bdev,
337 sector_t block, unsigned size)
338{
339 gfp_t gfp;
340
341 gfp = mapping_gfp_constraint(bdev->bd_inode->i_mapping, ~__GFP_FS);
342 gfp |= __GFP_NOFAIL;
343
344 return bdev_getblk(bdev, block, size, gfp);
345}
346
347static inline struct buffer_head *__getblk(struct block_device *bdev,
348 sector_t block, unsigned size)
349{
350 gfp_t gfp;
351
352 gfp = mapping_gfp_constraint(bdev->bd_inode->i_mapping, ~__GFP_FS);
353 gfp |= __GFP_MOVABLE | __GFP_NOFAIL;
354
355 return bdev_getblk(bdev, block, size, gfp);
356}
357
358static inline struct buffer_head *sb_getblk(struct super_block *sb,
359 sector_t block)
360{
361 return __getblk(sb->s_bdev, block, sb->s_blocksize);
362}
363
364static inline struct buffer_head *sb_getblk_gfp(struct super_block *sb,
365 sector_t block, gfp_t gfp)
366{
367 return bdev_getblk(sb->s_bdev, block, sb->s_blocksize, gfp);
368}
369
370static inline struct buffer_head *
371sb_find_get_block(struct super_block *sb, sector_t block)
372{
373 return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
374}
375
376static inline void
377map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
378{
379 set_buffer_mapped(bh);
380 bh->b_bdev = sb->s_bdev;
381 bh->b_blocknr = block;
382 bh->b_size = sb->s_blocksize;
383}
384
385static inline void wait_on_buffer(struct buffer_head *bh)
386{
387 might_sleep();
388 if (buffer_locked(bh))
389 __wait_on_buffer(bh);
390}
391
392static inline int trylock_buffer(struct buffer_head *bh)
393{
394 return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));
395}
396
397static inline void lock_buffer(struct buffer_head *bh)
398{
399 might_sleep();
400 if (!trylock_buffer(bh))
401 __lock_buffer(bh);
402}
403
404static inline void bh_readahead(struct buffer_head *bh, blk_opf_t op_flags)
405{
406 if (!buffer_uptodate(bh) && trylock_buffer(bh)) {
407 if (!buffer_uptodate(bh))
408 __bh_read(bh, op_flags, false);
409 else
410 unlock_buffer(bh);
411 }
412}
413
414static inline void bh_read_nowait(struct buffer_head *bh, blk_opf_t op_flags)
415{
416 if (!bh_uptodate_or_lock(bh))
417 __bh_read(bh, op_flags, false);
418}
419
420/* Returns 1 if buffer uptodated, 0 on success, and -EIO on error. */
421static inline int bh_read(struct buffer_head *bh, blk_opf_t op_flags)
422{
423 if (bh_uptodate_or_lock(bh))
424 return 1;
425 return __bh_read(bh, op_flags, true);
426}
427
428static inline void bh_read_batch(int nr, struct buffer_head *bhs[])
429{
430 __bh_read_batch(nr, bhs, 0, true);
431}
432
433static inline void bh_readahead_batch(int nr, struct buffer_head *bhs[],
434 blk_opf_t op_flags)
435{
436 __bh_read_batch(nr, bhs, op_flags, false);
437}
438
439/**
440 * __bread() - reads a specified block and returns the bh
441 * @bdev: the block_device to read from
442 * @block: number of block
443 * @size: size (in bytes) to read
444 *
445 * Reads a specified block, and returns buffer head that contains it.
446 * The page cache is allocated from movable area so that it can be migrated.
447 * It returns NULL if the block was unreadable.
448 */
449static inline struct buffer_head *
450__bread(struct block_device *bdev, sector_t block, unsigned size)
451{
452 return __bread_gfp(bdev, block, size, __GFP_MOVABLE);
453}
454
455/**
456 * get_nth_bh - Get a reference on the n'th buffer after this one.
457 * @bh: The buffer to start counting from.
458 * @count: How many buffers to skip.
459 *
460 * This is primarily useful for finding the nth buffer in a folio; in
461 * that case you pass the head buffer and the byte offset in the folio
462 * divided by the block size. It can be used for other purposes, but
463 * it will wrap at the end of the folio rather than returning NULL or
464 * proceeding to the next folio for you.
465 *
466 * Return: The requested buffer with an elevated refcount.
467 */
468static inline __must_check
469struct buffer_head *get_nth_bh(struct buffer_head *bh, unsigned int count)
470{
471 while (count--)
472 bh = bh->b_this_page;
473 get_bh(bh);
474 return bh;
475}
476
477bool block_dirty_folio(struct address_space *mapping, struct folio *folio);
478
479#ifdef CONFIG_BUFFER_HEAD
480
481void buffer_init(void);
482bool try_to_free_buffers(struct folio *folio);
483int inode_has_buffers(struct inode *inode);
484void invalidate_inode_buffers(struct inode *inode);
485int remove_inode_buffers(struct inode *inode);
486int sync_mapping_buffers(struct address_space *mapping);
487void invalidate_bh_lrus(void);
488void invalidate_bh_lrus_cpu(void);
489bool has_bh_in_lru(int cpu, void *dummy);
490extern int buffer_heads_over_limit;
491
492#else /* CONFIG_BUFFER_HEAD */
493
494static inline void buffer_init(void) {}
495static inline bool try_to_free_buffers(struct folio *folio) { return true; }
496static inline int inode_has_buffers(struct inode *inode) { return 0; }
497static inline void invalidate_inode_buffers(struct inode *inode) {}
498static inline int remove_inode_buffers(struct inode *inode) { return 1; }
499static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
500static inline void invalidate_bh_lrus(void) {}
501static inline void invalidate_bh_lrus_cpu(void) {}
502static inline bool has_bh_in_lru(int cpu, void *dummy) { return false; }
503#define buffer_heads_over_limit 0
504
505#endif /* CONFIG_BUFFER_HEAD */
506#endif /* _LINUX_BUFFER_HEAD_H */