Line data Source code
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 :
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 :
46 : struct page;
47 : struct buffer_head;
48 : struct address_space;
49 : typedef 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 : */
60 : struct 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) \
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 72968 : BUFFER_FNS(Uptodate, uptodate)
121 40227 : BUFFER_FNS(Dirty, dirty)
122 11975 : TAS_BUFFER_FNS(Dirty, dirty)
123 25050 : BUFFER_FNS(Lock, locked)
124 0 : BUFFER_FNS(Req, req)
125 6715 : TAS_BUFFER_FNS(Req, req)
126 39088 : BUFFER_FNS(Mapped, mapped)
127 9255 : BUFFER_FNS(New, new)
128 4 : BUFFER_FNS(Async_Read, async_read)
129 5015 : BUFFER_FNS(Async_Write, async_write)
130 13527 : BUFFER_FNS(Delay, delay)
131 517 : BUFFER_FNS(Boundary, boundary)
132 6010 : BUFFER_FNS(Write_EIO, write_io_error)
133 7982 : BUFFER_FNS(Unwritten, unwritten)
134 21423 : BUFFER_FNS(Meta, meta)
135 21423 : 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 1607 : static inline void clean_bdev_bh_alias(struct buffer_head *bh)
178 : {
179 1607 : clean_bdev_aliases(bh->b_bdev, bh->b_blocknr, 1);
180 0 : }
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 */
247 304 : static inline vm_fault_t block_page_mkwrite_return(int err)
248 : {
249 304 : 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 0 : 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 61839 : static inline void get_bh(struct buffer_head *bh)
276 : {
277 61839 : atomic_inc(&bh->b_count);
278 61838 : }
279 :
280 64603 : static inline void put_bh(struct buffer_head *bh)
281 : {
282 64603 : smp_mb__before_atomic();
283 64603 : atomic_dec(&bh->b_count);
284 64603 : }
285 :
286 47718 : static inline void brelse(struct buffer_head *bh)
287 : {
288 37252 : if (bh)
289 44174 : __brelse(bh);
290 15 : }
291 :
292 0 : static inline void bforget(struct buffer_head *bh)
293 : {
294 0 : if (bh)
295 0 : __bforget(bh);
296 : }
297 :
298 : static inline struct buffer_head *
299 0 : sb_bread(struct super_block *sb, sector_t block)
300 : {
301 0 : return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
302 : }
303 :
304 : static inline struct buffer_head *
305 : sb_bread_unmovable(struct super_block *sb, sector_t block)
306 : {
307 : return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, 0);
308 : }
309 :
310 : static inline void
311 : sb_breadahead(struct super_block *sb, sector_t block)
312 : {
313 : __breadahead(sb->s_bdev, block, sb->s_blocksize);
314 : }
315 :
316 : static inline void
317 : sb_breadahead_unmovable(struct super_block *sb, sector_t block)
318 : {
319 : __breadahead_gfp(sb->s_bdev, block, sb->s_blocksize, 0);
320 : }
321 :
322 : static inline struct buffer_head *
323 29021 : sb_getblk(struct super_block *sb, sector_t block)
324 : {
325 29021 : return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
326 : }
327 :
328 :
329 : static inline struct buffer_head *
330 3427 : sb_getblk_gfp(struct super_block *sb, sector_t block, gfp_t gfp)
331 : {
332 3427 : return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, gfp);
333 : }
334 :
335 : static inline struct buffer_head *
336 77 : sb_find_get_block(struct super_block *sb, sector_t block)
337 : {
338 77 : return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
339 : }
340 :
341 : static inline void
342 1821 : map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
343 : {
344 1821 : set_buffer_mapped(bh);
345 1821 : bh->b_bdev = sb->s_bdev;
346 1821 : bh->b_blocknr = block;
347 1821 : bh->b_size = sb->s_blocksize;
348 1821 : }
349 :
350 6779 : static inline void wait_on_buffer(struct buffer_head *bh)
351 : {
352 6779 : might_sleep();
353 6779 : if (buffer_locked(bh))
354 799 : __wait_on_buffer(bh);
355 6779 : }
356 :
357 9921 : static inline int trylock_buffer(struct buffer_head *bh)
358 : {
359 13930 : return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));
360 : }
361 :
362 5097 : static inline void lock_buffer(struct buffer_head *bh)
363 : {
364 5097 : might_sleep();
365 5097 : if (!trylock_buffer(bh))
366 0 : __lock_buffer(bh);
367 5097 : }
368 :
369 1 : static inline struct buffer_head *getblk_unmovable(struct block_device *bdev,
370 : sector_t block,
371 : unsigned size)
372 : {
373 1 : return __getblk_gfp(bdev, block, size, 0);
374 : }
375 :
376 126 : static inline struct buffer_head *__getblk(struct block_device *bdev,
377 : sector_t block,
378 : unsigned size)
379 : {
380 126 : 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 0 : __bread(struct block_device *bdev, sector_t block, unsigned size)
395 : {
396 0 : 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 : #define buffer_heads_over_limit 0
410 :
411 : #endif /* CONFIG_BLOCK */
412 : #endif /* _LINUX_BUFFER_HEAD_H */
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