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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 | */ | |
85 | #define BUFFER_FNS(bit, name) \ | |
86 | static __always_inline void set_buffer_##name(struct buffer_head *bh) \ | |
87 | { \ | |
88 | set_bit(BH_##bit, &(bh)->b_state); \ | |
89 | } \ | |
90 | static __always_inline void clear_buffer_##name(struct buffer_head *bh) \ | |
91 | { \ | |
92 | clear_bit(BH_##bit, &(bh)->b_state); \ | |
93 | } \ | |
94 | static __always_inline int buffer_##name(const struct buffer_head *bh) \ | |
95 | { \ | |
96 | return test_bit(BH_##bit, &(bh)->b_state); \ | |
97 | } | |
98 | ||
99 | /* | |
100 | * test_set_buffer_foo() and test_clear_buffer_foo() | |
101 | */ | |
102 | #define TAS_BUFFER_FNS(bit, name) \ | |
103 | static __always_inline int test_set_buffer_##name(struct buffer_head *bh) \ | |
104 | { \ | |
105 | return test_and_set_bit(BH_##bit, &(bh)->b_state); \ | |
106 | } \ | |
107 | static __always_inline int test_clear_buffer_##name(struct buffer_head *bh) \ | |
108 | { \ | |
109 | return test_and_clear_bit(BH_##bit, &(bh)->b_state); \ | |
110 | } \ | |
111 | ||
112 | /* | |
113 | * Emit the buffer bitops functions. Note that there are also functions | |
114 | * of the form "mark_buffer_foo()". These are higher-level functions which | |
115 | * do something in addition to setting a b_state bit. | |
116 | */ | |
117 | BUFFER_FNS(Uptodate, uptodate) | |
118 | BUFFER_FNS(Dirty, dirty) | |
119 | TAS_BUFFER_FNS(Dirty, dirty) | |
120 | BUFFER_FNS(Lock, locked) | |
121 | BUFFER_FNS(Req, req) | |
122 | TAS_BUFFER_FNS(Req, req) | |
123 | BUFFER_FNS(Mapped, mapped) | |
124 | BUFFER_FNS(New, new) | |
125 | BUFFER_FNS(Async_Read, async_read) | |
126 | BUFFER_FNS(Async_Write, async_write) | |
127 | BUFFER_FNS(Delay, delay) | |
128 | BUFFER_FNS(Boundary, boundary) | |
129 | BUFFER_FNS(Write_EIO, write_io_error) | |
130 | BUFFER_FNS(Unwritten, unwritten) | |
131 | BUFFER_FNS(Meta, meta) | |
132 | BUFFER_FNS(Prio, prio) | |
133 | BUFFER_FNS(Defer_Completion, defer_completion) | |
134 | ||
135 | #define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK) | |
136 | ||
137 | /* If we *know* page->private refers to buffer_heads */ | |
138 | #define page_buffers(page) \ | |
139 | ({ \ | |
140 | BUG_ON(!PagePrivate(page)); \ | |
141 | ((struct buffer_head *)page_private(page)); \ | |
142 | }) | |
143 | #define page_has_buffers(page) PagePrivate(page) | |
144 | ||
145 | void buffer_check_dirty_writeback(struct page *page, | |
146 | bool *dirty, bool *writeback); | |
147 | ||
148 | /* | |
149 | * Declarations | |
150 | */ | |
151 | ||
152 | void mark_buffer_dirty(struct buffer_head *bh); | |
153 | void mark_buffer_write_io_error(struct buffer_head *bh); | |
154 | void init_buffer(struct buffer_head *, bh_end_io_t *, void *); | |
155 | void touch_buffer(struct buffer_head *bh); | |
156 | void set_bh_page(struct buffer_head *bh, | |
157 | struct page *page, unsigned long offset); | |
158 | int try_to_free_buffers(struct page *); | |
159 | struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, | |
160 | bool retry); | |
161 | void create_empty_buffers(struct page *, unsigned long, | |
162 | unsigned long b_state); | |
163 | void end_buffer_read_sync(struct buffer_head *bh, int uptodate); | |
164 | void end_buffer_write_sync(struct buffer_head *bh, int uptodate); | |
165 | void end_buffer_async_write(struct buffer_head *bh, int uptodate); | |
166 | ||
167 | /* Things to do with buffers at mapping->private_list */ | |
168 | void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode); | |
169 | int inode_has_buffers(struct inode *); | |
170 | void invalidate_inode_buffers(struct inode *); | |
171 | int remove_inode_buffers(struct inode *inode); | |
172 | int sync_mapping_buffers(struct address_space *mapping); | |
173 | void clean_bdev_aliases(struct block_device *bdev, sector_t block, | |
174 | sector_t len); | |
175 | static inline void clean_bdev_bh_alias(struct buffer_head *bh) | |
176 | { | |
177 | clean_bdev_aliases(bh->b_bdev, bh->b_blocknr, 1); | |
178 | } | |
179 | ||
180 | void mark_buffer_async_write(struct buffer_head *bh); | |
181 | void __wait_on_buffer(struct buffer_head *); | |
182 | wait_queue_head_t *bh_waitq_head(struct buffer_head *bh); | |
183 | struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block, | |
184 | unsigned size); | |
185 | struct buffer_head *__getblk_gfp(struct block_device *bdev, sector_t block, | |
186 | unsigned size, gfp_t gfp); | |
187 | void __brelse(struct buffer_head *); | |
188 | void __bforget(struct buffer_head *); | |
189 | void __breadahead(struct block_device *, sector_t block, unsigned int size); | |
190 | struct buffer_head *__bread_gfp(struct block_device *, | |
191 | sector_t block, unsigned size, gfp_t gfp); | |
192 | void invalidate_bh_lrus(void); | |
193 | struct buffer_head *alloc_buffer_head(gfp_t gfp_flags); | |
194 | void free_buffer_head(struct buffer_head * bh); | |
195 | void unlock_buffer(struct buffer_head *bh); | |
196 | void __lock_buffer(struct buffer_head *bh); | |
197 | void ll_rw_block(int, int, int, struct buffer_head * bh[]); | |
198 | int sync_dirty_buffer(struct buffer_head *bh); | |
199 | int __sync_dirty_buffer(struct buffer_head *bh, int op_flags); | |
200 | void write_dirty_buffer(struct buffer_head *bh, int op_flags); | |
201 | int submit_bh(int, int, struct buffer_head *); | |
202 | void write_boundary_block(struct block_device *bdev, | |
203 | sector_t bblock, unsigned blocksize); | |
204 | int bh_uptodate_or_lock(struct buffer_head *bh); | |
205 | int bh_submit_read(struct buffer_head *bh); | |
206 | loff_t page_cache_seek_hole_data(struct inode *inode, loff_t offset, | |
207 | loff_t length, int whence); | |
208 | ||
209 | extern int buffer_heads_over_limit; | |
210 | ||
211 | /* | |
212 | * Generic address_space_operations implementations for buffer_head-backed | |
213 | * address_spaces. | |
214 | */ | |
215 | void block_invalidatepage(struct page *page, unsigned int offset, | |
216 | unsigned int length); | |
217 | int block_write_full_page(struct page *page, get_block_t *get_block, | |
218 | struct writeback_control *wbc); | |
219 | int __block_write_full_page(struct inode *inode, struct page *page, | |
220 | get_block_t *get_block, struct writeback_control *wbc, | |
221 | bh_end_io_t *handler); | |
222 | int block_read_full_page(struct page*, get_block_t*); | |
223 | int block_is_partially_uptodate(struct page *page, unsigned long from, | |
224 | unsigned long count); | |
225 | int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len, | |
226 | unsigned flags, struct page **pagep, get_block_t *get_block); | |
227 | int __block_write_begin(struct page *page, loff_t pos, unsigned len, | |
228 | get_block_t *get_block); | |
229 | int block_write_end(struct file *, struct address_space *, | |
230 | loff_t, unsigned, unsigned, | |
231 | struct page *, void *); | |
232 | int generic_write_end(struct file *, struct address_space *, | |
233 | loff_t, unsigned, unsigned, | |
234 | struct page *, void *); | |
235 | void page_zero_new_buffers(struct page *page, unsigned from, unsigned to); | |
236 | void clean_page_buffers(struct page *page); | |
237 | int cont_write_begin(struct file *, struct address_space *, loff_t, | |
238 | unsigned, unsigned, struct page **, void **, | |
239 | get_block_t *, loff_t *); | |
240 | int generic_cont_expand_simple(struct inode *inode, loff_t size); | |
241 | int block_commit_write(struct page *page, unsigned from, unsigned to); | |
242 | int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, | |
243 | get_block_t get_block); | |
244 | /* Convert errno to return value from ->page_mkwrite() call */ | |
245 | static inline int block_page_mkwrite_return(int err) | |
246 | { | |
247 | if (err == 0) | |
248 | return VM_FAULT_LOCKED; | |
249 | if (err == -EFAULT || err == -EAGAIN) | |
250 | return VM_FAULT_NOPAGE; | |
251 | if (err == -ENOMEM) | |
252 | return VM_FAULT_OOM; | |
253 | /* -ENOSPC, -EDQUOT, -EIO ... */ | |
254 | return VM_FAULT_SIGBUS; | |
255 | } | |
256 | sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *); | |
257 | int block_truncate_page(struct address_space *, loff_t, get_block_t *); | |
258 | int nobh_write_begin(struct address_space *, loff_t, unsigned, unsigned, | |
259 | struct page **, void **, get_block_t*); | |
260 | int nobh_write_end(struct file *, struct address_space *, | |
261 | loff_t, unsigned, unsigned, | |
262 | struct page *, void *); | |
263 | int nobh_truncate_page(struct address_space *, loff_t, get_block_t *); | |
264 | int nobh_writepage(struct page *page, get_block_t *get_block, | |
265 | struct writeback_control *wbc); | |
266 | ||
267 | void buffer_init(void); | |
268 | ||
269 | /* | |
270 | * inline definitions | |
271 | */ | |
272 | ||
273 | static inline void attach_page_buffers(struct page *page, | |
274 | struct buffer_head *head) | |
275 | { | |
276 | get_page(page); | |
277 | SetPagePrivate(page); | |
278 | set_page_private(page, (unsigned long)head); | |
279 | } | |
280 | ||
281 | static inline void get_bh(struct buffer_head *bh) | |
282 | { | |
283 | atomic_inc(&bh->b_count); | |
284 | } | |
285 | ||
286 | static inline void put_bh(struct buffer_head *bh) | |
287 | { | |
288 | smp_mb__before_atomic(); | |
289 | atomic_dec(&bh->b_count); | |
290 | } | |
291 | ||
292 | static inline void brelse(struct buffer_head *bh) | |
293 | { | |
294 | if (bh) | |
295 | __brelse(bh); | |
296 | } | |
297 | ||
298 | static inline void bforget(struct buffer_head *bh) | |
299 | { | |
300 | if (bh) | |
301 | __bforget(bh); | |
302 | } | |
303 | ||
304 | static inline struct buffer_head * | |
305 | sb_bread(struct super_block *sb, sector_t block) | |
306 | { | |
307 | return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE); | |
308 | } | |
309 | ||
310 | static inline struct buffer_head * | |
311 | sb_bread_unmovable(struct super_block *sb, sector_t block) | |
312 | { | |
313 | return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, 0); | |
314 | } | |
315 | ||
316 | static inline void | |
317 | sb_breadahead(struct super_block *sb, sector_t block) | |
318 | { | |
319 | __breadahead(sb->s_bdev, block, sb->s_blocksize); | |
320 | } | |
321 | ||
322 | static inline struct buffer_head * | |
323 | sb_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 | ||
329 | static inline struct buffer_head * | |
330 | sb_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 | ||
335 | static inline struct buffer_head * | |
336 | sb_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 | ||
341 | static inline void | |
342 | map_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 | ||
350 | static 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 | ||
357 | static inline int trylock_buffer(struct buffer_head *bh) | |
358 | { | |
359 | return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state)); | |
360 | } | |
361 | ||
362 | static inline void lock_buffer(struct buffer_head *bh) | |
363 | { | |
364 | might_sleep(); | |
365 | if (!trylock_buffer(bh)) | |
366 | __lock_buffer(bh); | |
367 | } | |
368 | ||
369 | static 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 | ||
376 | static 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 | */ | |
393 | static 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 | ||
399 | extern int __set_page_dirty_buffers(struct page *page); | |
400 | ||
401 | #else /* CONFIG_BLOCK */ | |
402 | ||
403 | static inline void buffer_init(void) {} | |
404 | static inline int try_to_free_buffers(struct page *page) { return 1; } | |
405 | static inline int inode_has_buffers(struct inode *inode) { return 0; } | |
406 | static inline void invalidate_inode_buffers(struct inode *inode) {} | |
407 | static inline int remove_inode_buffers(struct inode *inode) { return 1; } | |
408 | static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; } | |
409 | ||
410 | #endif /* CONFIG_BLOCK */ | |
411 | #endif /* _LINUX_BUFFER_HEAD_H */ |