1 /* SPDX-License-Identifier: GPL-2.0 */
3 * include/linux/buffer_head.h
5 * Everything to do with buffer_heads.
8 #ifndef _LINUX_BUFFER_HEAD_H
9 #define _LINUX_BUFFER_HEAD_H
11 #include <linux/types.h>
13 #include <linux/linkage.h>
14 #include <linux/pagemap.h>
15 #include <linux/wait.h>
16 #include <linux/atomic.h>
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
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 */
42 BH_PrivateStart,/* not a state bit, but the first bit available
43 * for private allocation by other entities
47 #define MAX_BUF_PER_PAGE (PAGE_SIZE / 512)
52 typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
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).
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 */
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 */
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
78 atomic_t b_count; /* users using this buffer_head */
82 * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
83 * and buffer_foo() functions.
85 #define BUFFER_FNS(bit, name) \
86 static __always_inline void set_buffer_##name(struct buffer_head *bh) \
88 set_bit(BH_##bit, &(bh)->b_state); \
90 static __always_inline void clear_buffer_##name(struct buffer_head *bh) \
92 clear_bit(BH_##bit, &(bh)->b_state); \
94 static __always_inline int buffer_##name(const struct buffer_head *bh) \
96 return test_bit(BH_##bit, &(bh)->b_state); \
100 * test_set_buffer_foo() and test_clear_buffer_foo()
102 #define TAS_BUFFER_FNS(bit, name) \
103 static __always_inline int test_set_buffer_##name(struct buffer_head *bh) \
105 return test_and_set_bit(BH_##bit, &(bh)->b_state); \
107 static __always_inline int test_clear_buffer_##name(struct buffer_head *bh) \
109 return test_and_clear_bit(BH_##bit, &(bh)->b_state); \
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.
117 BUFFER_FNS(Uptodate, uptodate)
118 BUFFER_FNS(Dirty, dirty)
119 TAS_BUFFER_FNS(Dirty, dirty)
120 BUFFER_FNS(Lock, locked)
122 TAS_BUFFER_FNS(Req, req)
123 BUFFER_FNS(Mapped, mapped)
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)
135 #define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK)
137 /* If we *know* page->private refers to buffer_heads */
138 #define page_buffers(page) \
140 BUG_ON(!PagePrivate(page)); \
141 ((struct buffer_head *)page_private(page)); \
143 #define page_has_buffers(page) PagePrivate(page)
145 void buffer_check_dirty_writeback(struct page *page,
146 bool *dirty, bool *writeback);
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,
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);
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,
175 static inline void clean_bdev_bh_alias(struct buffer_head *bh)
177 clean_bdev_aliases(bh->b_bdev, bh->b_blocknr, 1);
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,
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 void __breadahead_gfp(struct block_device *, sector_t block, unsigned int size,
192 struct buffer_head *__bread_gfp(struct block_device *,
193 sector_t block, unsigned size, gfp_t gfp);
194 void invalidate_bh_lrus(void);
195 struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
196 void free_buffer_head(struct buffer_head * bh);
197 void unlock_buffer(struct buffer_head *bh);
198 void __lock_buffer(struct buffer_head *bh);
199 void ll_rw_block(int, int, int, struct buffer_head * bh[]);
200 int sync_dirty_buffer(struct buffer_head *bh);
201 int __sync_dirty_buffer(struct buffer_head *bh, int op_flags);
202 void write_dirty_buffer(struct buffer_head *bh, int op_flags);
203 int submit_bh(int, int, struct buffer_head *);
204 void write_boundary_block(struct block_device *bdev,
205 sector_t bblock, unsigned blocksize);
206 int bh_uptodate_or_lock(struct buffer_head *bh);
207 int bh_submit_read(struct buffer_head *bh);
208 loff_t page_cache_seek_hole_data(struct inode *inode, loff_t offset,
209 loff_t length, int whence);
211 extern int buffer_heads_over_limit;
214 * Generic address_space_operations implementations for buffer_head-backed
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 int block_page_mkwrite_return(int err)
250 return VM_FAULT_LOCKED;
251 if (err == -EFAULT || err == -EAGAIN)
252 return VM_FAULT_NOPAGE;
255 /* -ENOSPC, -EDQUOT, -EIO ... */
256 return VM_FAULT_SIGBUS;
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);
269 void buffer_init(void);
275 static inline void attach_page_buffers(struct page *page,
276 struct buffer_head *head)
279 SetPagePrivate(page);
280 set_page_private(page, (unsigned long)head);
283 static inline void get_bh(struct buffer_head *bh)
285 atomic_inc(&bh->b_count);
288 static inline void put_bh(struct buffer_head *bh)
290 smp_mb__before_atomic();
291 atomic_dec(&bh->b_count);
294 static inline void brelse(struct buffer_head *bh)
300 static inline void bforget(struct buffer_head *bh)
306 static inline struct buffer_head *
307 sb_bread(struct super_block *sb, sector_t block)
309 return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
312 static inline struct buffer_head *
313 sb_bread_unmovable(struct super_block *sb, sector_t block)
315 return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, 0);
319 sb_breadahead(struct super_block *sb, sector_t block)
321 __breadahead(sb->s_bdev, block, sb->s_blocksize);
325 sb_breadahead_unmovable(struct super_block *sb, sector_t block)
327 __breadahead_gfp(sb->s_bdev, block, sb->s_blocksize, 0);
330 static inline struct buffer_head *
331 sb_getblk(struct super_block *sb, sector_t block)
333 return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
337 static inline struct buffer_head *
338 sb_getblk_gfp(struct super_block *sb, sector_t block, gfp_t gfp)
340 return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, gfp);
343 static inline struct buffer_head *
344 sb_find_get_block(struct super_block *sb, sector_t block)
346 return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
350 map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
352 set_buffer_mapped(bh);
353 bh->b_bdev = sb->s_bdev;
354 bh->b_blocknr = block;
355 bh->b_size = sb->s_blocksize;
358 static inline void wait_on_buffer(struct buffer_head *bh)
361 if (buffer_locked(bh))
362 __wait_on_buffer(bh);
365 static inline int trylock_buffer(struct buffer_head *bh)
367 return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));
370 static inline void lock_buffer(struct buffer_head *bh)
373 if (!trylock_buffer(bh))
377 static inline struct buffer_head *getblk_unmovable(struct block_device *bdev,
381 return __getblk_gfp(bdev, block, size, 0);
384 static inline struct buffer_head *__getblk(struct block_device *bdev,
388 return __getblk_gfp(bdev, block, size, __GFP_MOVABLE);
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
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.
401 static inline struct buffer_head *
402 __bread(struct block_device *bdev, sector_t block, unsigned size)
404 return __bread_gfp(bdev, block, size, __GFP_MOVABLE);
407 extern int __set_page_dirty_buffers(struct page *page);
409 #else /* CONFIG_BLOCK */
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; }
418 #endif /* CONFIG_BLOCK */
419 #endif /* _LINUX_BUFFER_HEAD_H */