2 * include/linux/buffer_head.h
4 * Everything to do with buffer_heads.
7 #ifndef _LINUX_BUFFER_HEAD_H
8 #define _LINUX_BUFFER_HEAD_H
10 #include <linux/types.h>
12 #include <linux/linkage.h>
13 #include <linux/pagemap.h>
14 #include <linux/wait.h>
15 #include <linux/atomic.h>
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 BH_Uptodate_Lock,/* Used by the first bh in a page, to serialise
25 * IO completion of other buffers in the page
28 BH_Mapped, /* Has a disk mapping */
29 BH_New, /* Disk mapping was newly created by get_block */
30 BH_Async_Read, /* Is under end_buffer_async_read I/O */
31 BH_Async_Write, /* Is under end_buffer_async_write I/O */
32 BH_Delay, /* Buffer is not yet allocated on disk */
33 BH_Boundary, /* Block is followed by a discontiguity */
34 BH_Write_EIO, /* I/O error on write */
35 BH_Unwritten, /* Buffer is allocated on disk but not written */
36 BH_Quiet, /* Buffer Error Prinks to be quiet */
37 BH_Meta, /* Buffer contains metadata */
38 BH_Prio, /* Buffer should be submitted with REQ_PRIO */
39 BH_Defer_Completion, /* Defer AIO completion to workqueue */
41 BH_PrivateStart,/* not a state bit, but the first bit available
42 * for private allocation by other entities
46 #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512)
51 typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
54 * Historically, a buffer_head was used to map a single block
55 * within a page, and of course as the unit of I/O through the
56 * filesystem and block layers. Nowadays the basic I/O unit
57 * is the bio, and buffer_heads are used for extracting block
58 * mappings (via a get_block_t call), for tracking state within
59 * a page (via a page_mapping) and for wrapping bio submission
60 * for backward compatibility reasons (e.g. submit_bh).
63 unsigned long b_state; /* buffer state bitmap (see above) */
64 struct buffer_head *b_this_page;/* circular list of page's buffers */
65 struct page *b_page; /* the page this bh is mapped to */
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 */
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
77 atomic_t b_count; /* users using this buffer_head */
78 #ifdef CONFIG_PREEMPT_RT_BASE
79 spinlock_t b_uptodate_lock;
80 #if IS_ENABLED(CONFIG_JBD2)
81 spinlock_t b_state_lock;
82 spinlock_t b_journal_head_lock;
87 static inline unsigned long bh_uptodate_lock_irqsave(struct buffer_head *bh)
91 #ifndef CONFIG_PREEMPT_RT_BASE
92 local_irq_save(flags);
93 bit_spin_lock(BH_Uptodate_Lock, &bh->b_state);
95 spin_lock_irqsave(&bh->b_uptodate_lock, flags);
101 bh_uptodate_unlock_irqrestore(struct buffer_head *bh, unsigned long flags)
103 #ifndef CONFIG_PREEMPT_RT_BASE
104 bit_spin_unlock(BH_Uptodate_Lock, &bh->b_state);
105 local_irq_restore(flags);
107 spin_unlock_irqrestore(&bh->b_uptodate_lock, flags);
111 static inline void buffer_head_init_locks(struct buffer_head *bh)
113 #ifdef CONFIG_PREEMPT_RT_BASE
114 spin_lock_init(&bh->b_uptodate_lock);
115 #if IS_ENABLED(CONFIG_JBD2)
116 spin_lock_init(&bh->b_state_lock);
117 spin_lock_init(&bh->b_journal_head_lock);
123 * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
124 * and buffer_foo() functions.
126 #define BUFFER_FNS(bit, name) \
127 static inline void set_buffer_##name(struct buffer_head *bh) \
129 set_bit(BH_##bit, &(bh)->b_state); \
131 static inline void clear_buffer_##name(struct buffer_head *bh) \
133 clear_bit(BH_##bit, &(bh)->b_state); \
135 static inline int buffer_##name(const struct buffer_head *bh) \
137 return test_bit(BH_##bit, &(bh)->b_state); \
141 * test_set_buffer_foo() and test_clear_buffer_foo()
143 #define TAS_BUFFER_FNS(bit, name) \
144 static inline int test_set_buffer_##name(struct buffer_head *bh) \
146 return test_and_set_bit(BH_##bit, &(bh)->b_state); \
148 static inline int test_clear_buffer_##name(struct buffer_head *bh) \
150 return test_and_clear_bit(BH_##bit, &(bh)->b_state); \
154 * Emit the buffer bitops functions. Note that there are also functions
155 * of the form "mark_buffer_foo()". These are higher-level functions which
156 * do something in addition to setting a b_state bit.
158 BUFFER_FNS(Uptodate, uptodate)
159 BUFFER_FNS(Dirty, dirty)
160 TAS_BUFFER_FNS(Dirty, dirty)
161 BUFFER_FNS(Lock, locked)
163 TAS_BUFFER_FNS(Req, req)
164 BUFFER_FNS(Mapped, mapped)
166 BUFFER_FNS(Async_Read, async_read)
167 BUFFER_FNS(Async_Write, async_write)
168 BUFFER_FNS(Delay, delay)
169 BUFFER_FNS(Boundary, boundary)
170 BUFFER_FNS(Write_EIO, write_io_error)
171 BUFFER_FNS(Unwritten, unwritten)
172 BUFFER_FNS(Meta, meta)
173 BUFFER_FNS(Prio, prio)
174 BUFFER_FNS(Defer_Completion, defer_completion)
176 #define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK)
178 /* If we *know* page->private refers to buffer_heads */
179 #define page_buffers(page) \
181 BUG_ON(!PagePrivate(page)); \
182 ((struct buffer_head *)page_private(page)); \
184 #define page_has_buffers(page) PagePrivate(page)
186 void buffer_check_dirty_writeback(struct page *page,
187 bool *dirty, bool *writeback);
193 void mark_buffer_dirty(struct buffer_head *bh);
194 void init_buffer(struct buffer_head *, bh_end_io_t *, void *);
195 void touch_buffer(struct buffer_head *bh);
196 void set_bh_page(struct buffer_head *bh,
197 struct page *page, unsigned long offset);
198 int try_to_free_buffers(struct page *);
199 struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
201 void create_empty_buffers(struct page *, unsigned long,
202 unsigned long b_state);
203 void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
204 void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
205 void end_buffer_async_write(struct buffer_head *bh, int uptodate);
207 /* Things to do with buffers at mapping->private_list */
208 void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
209 int inode_has_buffers(struct inode *);
210 void invalidate_inode_buffers(struct inode *);
211 int remove_inode_buffers(struct inode *inode);
212 int sync_mapping_buffers(struct address_space *mapping);
213 void unmap_underlying_metadata(struct block_device *bdev, sector_t block);
215 void mark_buffer_async_write(struct buffer_head *bh);
216 void __wait_on_buffer(struct buffer_head *);
217 wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
218 struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block,
220 struct buffer_head *__getblk_gfp(struct block_device *bdev, sector_t block,
221 unsigned size, gfp_t gfp);
222 void __brelse(struct buffer_head *);
223 void __bforget(struct buffer_head *);
224 void __breadahead(struct block_device *, sector_t block, unsigned int size);
225 struct buffer_head *__bread_gfp(struct block_device *,
226 sector_t block, unsigned size, gfp_t gfp);
227 void invalidate_bh_lrus(void);
228 struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
229 void free_buffer_head(struct buffer_head * bh);
230 void unlock_buffer(struct buffer_head *bh);
231 void __lock_buffer(struct buffer_head *bh);
232 void ll_rw_block(int, int, struct buffer_head * bh[]);
233 int sync_dirty_buffer(struct buffer_head *bh);
234 int __sync_dirty_buffer(struct buffer_head *bh, int rw);
235 void write_dirty_buffer(struct buffer_head *bh, int rw);
236 int _submit_bh(int rw, struct buffer_head *bh, unsigned long bio_flags);
237 int submit_bh(int, struct buffer_head *);
238 void write_boundary_block(struct block_device *bdev,
239 sector_t bblock, unsigned blocksize);
240 int bh_uptodate_or_lock(struct buffer_head *bh);
241 int bh_submit_read(struct buffer_head *bh);
243 extern int buffer_heads_over_limit;
246 * Generic address_space_operations implementations for buffer_head-backed
249 void block_invalidatepage(struct page *page, unsigned int offset,
250 unsigned int length);
251 int block_write_full_page(struct page *page, get_block_t *get_block,
252 struct writeback_control *wbc);
253 int block_read_full_page(struct page*, get_block_t*);
254 int block_is_partially_uptodate(struct page *page, unsigned long from,
255 unsigned long count);
256 int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
257 unsigned flags, struct page **pagep, get_block_t *get_block);
258 int __block_write_begin(struct page *page, loff_t pos, unsigned len,
259 get_block_t *get_block);
260 int block_write_end(struct file *, struct address_space *,
261 loff_t, unsigned, unsigned,
262 struct page *, void *);
263 int generic_write_end(struct file *, struct address_space *,
264 loff_t, unsigned, unsigned,
265 struct page *, void *);
266 void page_zero_new_buffers(struct page *page, unsigned from, unsigned to);
267 int cont_write_begin(struct file *, struct address_space *, loff_t,
268 unsigned, unsigned, struct page **, void **,
269 get_block_t *, loff_t *);
270 int generic_cont_expand_simple(struct inode *inode, loff_t size);
271 int block_commit_write(struct page *page, unsigned from, unsigned to);
272 int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
273 get_block_t get_block);
274 /* Convert errno to return value from ->page_mkwrite() call */
275 static inline int block_page_mkwrite_return(int err)
278 return VM_FAULT_LOCKED;
280 return VM_FAULT_NOPAGE;
284 return VM_FAULT_RETRY;
285 /* -ENOSPC, -EDQUOT, -EIO ... */
286 return VM_FAULT_SIGBUS;
288 sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
289 int block_truncate_page(struct address_space *, loff_t, get_block_t *);
290 int nobh_write_begin(struct address_space *, loff_t, unsigned, unsigned,
291 struct page **, void **, get_block_t*);
292 int nobh_write_end(struct file *, struct address_space *,
293 loff_t, unsigned, unsigned,
294 struct page *, void *);
295 int nobh_truncate_page(struct address_space *, loff_t, get_block_t *);
296 int nobh_writepage(struct page *page, get_block_t *get_block,
297 struct writeback_control *wbc);
299 void buffer_init(void);
305 static inline void attach_page_buffers(struct page *page,
306 struct buffer_head *head)
308 page_cache_get(page);
309 SetPagePrivate(page);
310 set_page_private(page, (unsigned long)head);
313 static inline void get_bh(struct buffer_head *bh)
315 atomic_inc(&bh->b_count);
318 static inline void put_bh(struct buffer_head *bh)
320 smp_mb__before_atomic();
321 atomic_dec(&bh->b_count);
324 static inline void brelse(struct buffer_head *bh)
330 static inline void bforget(struct buffer_head *bh)
336 static inline struct buffer_head *
337 sb_bread(struct super_block *sb, sector_t block)
339 return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
342 static inline struct buffer_head *
343 sb_bread_unmovable(struct super_block *sb, sector_t block)
345 return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, 0);
349 sb_breadahead(struct super_block *sb, sector_t block)
351 __breadahead(sb->s_bdev, block, sb->s_blocksize);
354 static inline struct buffer_head *
355 sb_getblk(struct super_block *sb, sector_t block)
357 return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
361 static inline struct buffer_head *
362 sb_getblk_gfp(struct super_block *sb, sector_t block, gfp_t gfp)
364 return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, gfp);
367 static inline struct buffer_head *
368 sb_find_get_block(struct super_block *sb, sector_t block)
370 return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
374 map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
376 set_buffer_mapped(bh);
377 bh->b_bdev = sb->s_bdev;
378 bh->b_blocknr = block;
379 bh->b_size = sb->s_blocksize;
382 static inline void wait_on_buffer(struct buffer_head *bh)
385 if (buffer_locked(bh))
386 __wait_on_buffer(bh);
389 static inline int trylock_buffer(struct buffer_head *bh)
391 return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));
394 static inline void lock_buffer(struct buffer_head *bh)
397 if (!trylock_buffer(bh))
401 static inline struct buffer_head *getblk_unmovable(struct block_device *bdev,
405 return __getblk_gfp(bdev, block, size, 0);
408 static inline struct buffer_head *__getblk(struct block_device *bdev,
412 return __getblk_gfp(bdev, block, size, __GFP_MOVABLE);
416 * __bread() - reads a specified block and returns the bh
417 * @bdev: the block_device to read from
418 * @block: number of block
419 * @size: size (in bytes) to read
421 * Reads a specified block, and returns buffer head that contains it.
422 * The page cache is allocated from movable area so that it can be migrated.
423 * It returns NULL if the block was unreadable.
425 static inline struct buffer_head *
426 __bread(struct block_device *bdev, sector_t block, unsigned size)
428 return __bread_gfp(bdev, block, size, __GFP_MOVABLE);
431 extern int __set_page_dirty_buffers(struct page *page);
433 #else /* CONFIG_BLOCK */
435 static inline void buffer_init(void) {}
436 static inline int try_to_free_buffers(struct page *page) { return 1; }
437 static inline int inode_has_buffers(struct inode *inode) { return 0; }
438 static inline void invalidate_inode_buffers(struct inode *inode) {}
439 static inline int remove_inode_buffers(struct inode *inode) { return 1; }
440 static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
442 #endif /* CONFIG_BLOCK */
443 #endif /* _LINUX_BUFFER_HEAD_H */