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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 : :
20 : : enum 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 : : BH_Uptodate_Lock,/* Used by the first bh in a page, to serialise
26 : : * IO completion of other buffers in the page
27 : : */
28 : :
29 : : BH_Mapped, /* Has a disk mapping */
30 : : BH_New, /* Disk mapping was newly created by get_block */
31 : : BH_Async_Read, /* Is under end_buffer_async_read I/O */
32 : : BH_Async_Write, /* Is under end_buffer_async_write I/O */
33 : : BH_Delay, /* Buffer is not yet allocated on disk */
34 : : BH_Boundary, /* Block is followed by a discontiguity */
35 : : BH_Write_EIO, /* I/O error on write */
36 : : BH_Unwritten, /* Buffer is allocated on disk but not written */
37 : : BH_Quiet, /* Buffer Error Prinks to be quiet */
38 : : BH_Meta, /* Buffer contains metadata */
39 : : BH_Prio, /* Buffer should be submitted with REQ_PRIO */
40 : : BH_Defer_Completion, /* Defer AIO completion to workqueue */
41 : :
42 : : BH_PrivateStart,/* not a state bit, but the first bit available
43 : : * for private allocation by other entities
44 : : */
45 : : };
46 : :
47 : : #define MAX_BUF_PER_PAGE (PAGE_SIZE / 512)
48 : :
49 : : struct page;
50 : : struct buffer_head;
51 : : struct address_space;
52 : : typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
53 : :
54 : : /*
55 : : * Historically, a buffer_head was used to map a single block
56 : : * within a page, and of course as the unit of I/O through the
57 : : * filesystem and block layers. Nowadays the basic I/O unit
58 : : * is the bio, and buffer_heads are used for extracting block
59 : : * mappings (via a get_block_t call), for tracking state within
60 : : * a page (via a page_mapping) and for wrapping bio submission
61 : : * for backward compatibility reasons (e.g. submit_bh).
62 : : */
63 : : struct buffer_head {
64 : : unsigned long b_state; /* buffer state bitmap (see above) */
65 : : struct buffer_head *b_this_page;/* circular list of page's buffers */
66 : : struct page *b_page; /* the page this bh is mapped to */
67 : :
68 : : sector_t b_blocknr; /* start block number */
69 : : size_t b_size; /* size of mapping */
70 : : char *b_data; /* pointer to data within the page */
71 : :
72 : : struct block_device *b_bdev;
73 : : bh_end_io_t *b_end_io; /* I/O completion */
74 : : void *b_private; /* reserved for b_end_io */
75 : : struct list_head b_assoc_buffers; /* associated with another mapping */
76 : : struct address_space *b_assoc_map; /* mapping this buffer is
77 : : associated with */
78 : : atomic_t b_count; /* users using this buffer_head */
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) \
88 : : static __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 : : } \
93 : : static __always_inline void clear_buffer_##name(struct buffer_head *bh) \
94 : : { \
95 : : clear_bit(BH_##bit, &(bh)->b_state); \
96 : : } \
97 : : static __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) \
106 : : static __always_inline int test_set_buffer_##name(struct buffer_head *bh) \
107 : : { \
108 : : return test_and_set_bit(BH_##bit, &(bh)->b_state); \
109 : : } \
110 : : static __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 : : */
120 : 3 : BUFFER_FNS(Uptodate, uptodate)
121 : 3 : BUFFER_FNS(Dirty, dirty)
122 : 3 : TAS_BUFFER_FNS(Dirty, dirty)
123 : 3 : BUFFER_FNS(Lock, locked)
124 : 1 : BUFFER_FNS(Req, req)
125 : 3 : TAS_BUFFER_FNS(Req, req)
126 : 3 : BUFFER_FNS(Mapped, mapped)
127 : 3 : BUFFER_FNS(New, new)
128 : 3 : BUFFER_FNS(Async_Read, async_read)
129 : 3 : BUFFER_FNS(Async_Write, async_write)
130 : 3 : BUFFER_FNS(Delay, delay)
131 : 3 : BUFFER_FNS(Boundary, boundary)
132 : 3 : BUFFER_FNS(Write_EIO, write_io_error)
133 : 3 : BUFFER_FNS(Unwritten, unwritten)
134 : 3 : BUFFER_FNS(Meta, meta)
135 : 3 : BUFFER_FNS(Prio, prio)
136 : 0 : BUFFER_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 : :
148 : : void buffer_check_dirty_writeback(struct page *page,
149 : : bool *dirty, bool *writeback);
150 : :
151 : : /*
152 : : * Declarations
153 : : */
154 : :
155 : : void mark_buffer_dirty(struct buffer_head *bh);
156 : : void mark_buffer_write_io_error(struct buffer_head *bh);
157 : : void touch_buffer(struct buffer_head *bh);
158 : : void set_bh_page(struct buffer_head *bh,
159 : : struct page *page, unsigned long offset);
160 : : int try_to_free_buffers(struct page *);
161 : : struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
162 : : bool retry);
163 : : void create_empty_buffers(struct page *, unsigned long,
164 : : unsigned long b_state);
165 : : void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
166 : : void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
167 : : void end_buffer_async_write(struct buffer_head *bh, int uptodate);
168 : :
169 : : /* Things to do with buffers at mapping->private_list */
170 : : void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
171 : : int inode_has_buffers(struct inode *);
172 : : void invalidate_inode_buffers(struct inode *);
173 : : int remove_inode_buffers(struct inode *inode);
174 : : int sync_mapping_buffers(struct address_space *mapping);
175 : : void clean_bdev_aliases(struct block_device *bdev, sector_t block,
176 : : sector_t len);
177 : 1 : static inline void clean_bdev_bh_alias(struct buffer_head *bh)
178 : : {
179 : 1 : clean_bdev_aliases(bh->b_bdev, bh->b_blocknr, 1);
180 : 1 : }
181 : :
182 : : void mark_buffer_async_write(struct buffer_head *bh);
183 : : void __wait_on_buffer(struct buffer_head *);
184 : : wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
185 : : struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block,
186 : : unsigned size);
187 : : struct buffer_head *__getblk_gfp(struct block_device *bdev, sector_t block,
188 : : unsigned size, gfp_t gfp);
189 : : void __brelse(struct buffer_head *);
190 : : void __bforget(struct buffer_head *);
191 : : void __breadahead(struct block_device *, sector_t block, unsigned int size);
192 : : void __breadahead_gfp(struct block_device *, sector_t block, unsigned int size,
193 : : gfp_t gfp);
194 : : struct buffer_head *__bread_gfp(struct block_device *,
195 : : sector_t block, unsigned size, gfp_t gfp);
196 : : void invalidate_bh_lrus(void);
197 : : struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
198 : : void free_buffer_head(struct buffer_head * bh);
199 : : void unlock_buffer(struct buffer_head *bh);
200 : : void __lock_buffer(struct buffer_head *bh);
201 : : void ll_rw_block(int, int, int, struct buffer_head * bh[]);
202 : : int sync_dirty_buffer(struct buffer_head *bh);
203 : : int __sync_dirty_buffer(struct buffer_head *bh, int op_flags);
204 : : void write_dirty_buffer(struct buffer_head *bh, int op_flags);
205 : : int submit_bh(int, int, struct buffer_head *);
206 : : void write_boundary_block(struct block_device *bdev,
207 : : sector_t bblock, unsigned blocksize);
208 : : int bh_uptodate_or_lock(struct buffer_head *bh);
209 : : int bh_submit_read(struct buffer_head *bh);
210 : :
211 : : extern int buffer_heads_over_limit;
212 : :
213 : : /*
214 : : * Generic address_space_operations implementations for buffer_head-backed
215 : : * address_spaces.
216 : : */
217 : : void block_invalidatepage(struct page *page, unsigned int offset,
218 : : unsigned int length);
219 : : int block_write_full_page(struct page *page, get_block_t *get_block,
220 : : struct writeback_control *wbc);
221 : : int __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);
224 : : int block_read_full_page(struct page*, get_block_t*);
225 : : int block_is_partially_uptodate(struct page *page, unsigned long from,
226 : : unsigned long count);
227 : : int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
228 : : unsigned flags, struct page **pagep, get_block_t *get_block);
229 : : int __block_write_begin(struct page *page, loff_t pos, unsigned len,
230 : : get_block_t *get_block);
231 : : int block_write_end(struct file *, struct address_space *,
232 : : loff_t, unsigned, unsigned,
233 : : struct page *, void *);
234 : : int generic_write_end(struct file *, struct address_space *,
235 : : loff_t, unsigned, unsigned,
236 : : struct page *, void *);
237 : : void page_zero_new_buffers(struct page *page, unsigned from, unsigned to);
238 : : void clean_page_buffers(struct page *page);
239 : : int cont_write_begin(struct file *, struct address_space *, loff_t,
240 : : unsigned, unsigned, struct page **, void **,
241 : : get_block_t *, loff_t *);
242 : : int generic_cont_expand_simple(struct inode *inode, loff_t size);
243 : : int block_commit_write(struct page *page, unsigned from, unsigned to);
244 : : int 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 */
247 : : static inline vm_fault_t block_page_mkwrite_return(int err)
248 : : {
249 : 3 : if (err == 0)
250 : : return VM_FAULT_LOCKED;
251 : 0 : if (err == -EFAULT || err == -EAGAIN)
252 : : return VM_FAULT_NOPAGE;
253 : 0 : if (err == -ENOMEM)
254 : : return VM_FAULT_OOM;
255 : : /* -ENOSPC, -EDQUOT, -EIO ... */
256 : : return VM_FAULT_SIGBUS;
257 : : }
258 : : sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
259 : : int block_truncate_page(struct address_space *, loff_t, get_block_t *);
260 : : int nobh_write_begin(struct address_space *, loff_t, unsigned, unsigned,
261 : : struct page **, void **, get_block_t*);
262 : : int nobh_write_end(struct file *, struct address_space *,
263 : : loff_t, unsigned, unsigned,
264 : : struct page *, void *);
265 : : int nobh_truncate_page(struct address_space *, loff_t, get_block_t *);
266 : : int nobh_writepage(struct page *page, get_block_t *get_block,
267 : : struct writeback_control *wbc);
268 : :
269 : : void buffer_init(void);
270 : :
271 : : /*
272 : : * inline definitions
273 : : */
274 : :
275 : : static inline void attach_page_buffers(struct page *page,
276 : : struct buffer_head *head)
277 : : {
278 : 3 : get_page(page);
279 : : SetPagePrivate(page);
280 : 3 : set_page_private(page, (unsigned long)head);
281 : : }
282 : :
283 : : static inline void get_bh(struct buffer_head *bh)
284 : : {
285 : 3 : atomic_inc(&bh->b_count);
286 : : }
287 : :
288 : 3 : static inline void put_bh(struct buffer_head *bh)
289 : : {
290 : 3 : smp_mb__before_atomic();
291 : 3 : atomic_dec(&bh->b_count);
292 : 3 : }
293 : :
294 : : static inline void brelse(struct buffer_head *bh)
295 : : {
296 : 3 : if (bh)
297 : 3 : __brelse(bh);
298 : : }
299 : :
300 : : static inline void bforget(struct buffer_head *bh)
301 : : {
302 : 0 : if (bh)
303 : 0 : __bforget(bh);
304 : : }
305 : :
306 : : static inline struct buffer_head *
307 : : sb_bread(struct super_block *sb, sector_t block)
308 : : {
309 : 3 : return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
310 : : }
311 : :
312 : : static inline struct buffer_head *
313 : : sb_bread_unmovable(struct super_block *sb, sector_t block)
314 : : {
315 : 3 : return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, 0);
316 : : }
317 : :
318 : : static inline void
319 : : sb_breadahead(struct super_block *sb, sector_t block)
320 : : {
321 : 3 : __breadahead(sb->s_bdev, block, sb->s_blocksize);
322 : : }
323 : :
324 : : static inline void
325 : : sb_breadahead_unmovable(struct super_block *sb, sector_t block)
326 : : {
327 : 3 : __breadahead_gfp(sb->s_bdev, block, sb->s_blocksize, 0);
328 : : }
329 : :
330 : : static inline struct buffer_head *
331 : : sb_getblk(struct super_block *sb, sector_t block)
332 : : {
333 : 3 : return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
334 : : }
335 : :
336 : :
337 : : static inline struct buffer_head *
338 : : sb_getblk_gfp(struct super_block *sb, sector_t block, gfp_t gfp)
339 : : {
340 : 3 : return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, gfp);
341 : : }
342 : :
343 : : static inline struct buffer_head *
344 : : sb_find_get_block(struct super_block *sb, sector_t block)
345 : : {
346 : 3 : return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
347 : : }
348 : :
349 : : static inline void
350 : 3 : map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
351 : : {
352 : : set_buffer_mapped(bh);
353 : 3 : bh->b_bdev = sb->s_bdev;
354 : 3 : bh->b_blocknr = block;
355 : 3 : bh->b_size = sb->s_blocksize;
356 : 3 : }
357 : :
358 : 3 : static inline void wait_on_buffer(struct buffer_head *bh)
359 : : {
360 : 3 : might_sleep();
361 : 3 : if (buffer_locked(bh))
362 : 3 : __wait_on_buffer(bh);
363 : 3 : }
364 : :
365 : : static inline int trylock_buffer(struct buffer_head *bh)
366 : : {
367 : 3 : return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));
368 : : }
369 : :
370 : 3 : static inline void lock_buffer(struct buffer_head *bh)
371 : : {
372 : 3 : might_sleep();
373 : 3 : if (!trylock_buffer(bh))
374 : 3 : __lock_buffer(bh);
375 : 3 : }
376 : :
377 : : static inline struct buffer_head *getblk_unmovable(struct block_device *bdev,
378 : : sector_t block,
379 : : unsigned size)
380 : : {
381 : 3 : return __getblk_gfp(bdev, block, size, 0);
382 : : }
383 : :
384 : : static inline struct buffer_head *__getblk(struct block_device *bdev,
385 : : sector_t block,
386 : : unsigned size)
387 : : {
388 : 3 : return __getblk_gfp(bdev, block, size, __GFP_MOVABLE);
389 : : }
390 : :
391 : : /**
392 : : * __bread() - reads a specified block and returns the bh
393 : : * @bdev: the block_device to read from
394 : : * @block: number of block
395 : : * @size: size (in bytes) to read
396 : : *
397 : : * Reads a specified block, and returns buffer head that contains it.
398 : : * The page cache is allocated from movable area so that it can be migrated.
399 : : * It returns NULL if the block was unreadable.
400 : : */
401 : : static inline struct buffer_head *
402 : : __bread(struct block_device *bdev, sector_t block, unsigned size)
403 : : {
404 : 0 : return __bread_gfp(bdev, block, size, __GFP_MOVABLE);
405 : : }
406 : :
407 : : extern int __set_page_dirty_buffers(struct page *page);
408 : :
409 : : #else /* CONFIG_BLOCK */
410 : :
411 : : static inline void buffer_init(void) {}
412 : : static inline int try_to_free_buffers(struct page *page) { return 1; }
413 : : static inline int inode_has_buffers(struct inode *inode) { return 0; }
414 : : static inline void invalidate_inode_buffers(struct inode *inode) {}
415 : : static inline int remove_inode_buffers(struct inode *inode) { return 1; }
416 : : static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
417 : :
418 : : #endif /* CONFIG_BLOCK */
419 : : #endif /* _LINUX_BUFFER_HEAD_H */
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