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 defined(CONFIG_JBD) || defined(CONFIG_JBD_MODULE) || \
81 defined(CONFIG_JBD2) || defined(CONFIG_JBD2_MODULE)
82 spinlock_t b_state_lock;
83 spinlock_t b_journal_head_lock;
88 static inline unsigned long bh_uptodate_lock_irqsave(struct buffer_head *bh)
92 #ifndef CONFIG_PREEMPT_RT_BASE
93 local_irq_save(flags);
94 bit_spin_lock(BH_Uptodate_Lock, &bh->b_state);
96 spin_lock_irqsave(&bh->b_uptodate_lock, flags);
102 bh_uptodate_unlock_irqrestore(struct buffer_head *bh, unsigned long flags)
104 #ifndef CONFIG_PREEMPT_RT_BASE
105 bit_spin_unlock(BH_Uptodate_Lock, &bh->b_state);
106 local_irq_restore(flags);
108 spin_unlock_irqrestore(&bh->b_uptodate_lock, flags);
112 static inline void buffer_head_init_locks(struct buffer_head *bh)
114 #ifdef CONFIG_PREEMPT_RT_BASE
115 spin_lock_init(&bh->b_uptodate_lock);
116 #if defined(CONFIG_JBD) || defined(CONFIG_JBD_MODULE) || \
117 defined(CONFIG_JBD2) || defined(CONFIG_JBD2_MODULE)
118 spin_lock_init(&bh->b_state_lock);
119 spin_lock_init(&bh->b_journal_head_lock);
125 * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
126 * and buffer_foo() functions.
128 #define BUFFER_FNS(bit, name) \
129 static inline void set_buffer_##name(struct buffer_head *bh) \
131 set_bit(BH_##bit, &(bh)->b_state); \
133 static inline void clear_buffer_##name(struct buffer_head *bh) \
135 clear_bit(BH_##bit, &(bh)->b_state); \
137 static inline int buffer_##name(const struct buffer_head *bh) \
139 return test_bit(BH_##bit, &(bh)->b_state); \
143 * test_set_buffer_foo() and test_clear_buffer_foo()
145 #define TAS_BUFFER_FNS(bit, name) \
146 static inline int test_set_buffer_##name(struct buffer_head *bh) \
148 return test_and_set_bit(BH_##bit, &(bh)->b_state); \
150 static inline int test_clear_buffer_##name(struct buffer_head *bh) \
152 return test_and_clear_bit(BH_##bit, &(bh)->b_state); \
156 * Emit the buffer bitops functions. Note that there are also functions
157 * of the form "mark_buffer_foo()". These are higher-level functions which
158 * do something in addition to setting a b_state bit.
160 BUFFER_FNS(Uptodate, uptodate)
161 BUFFER_FNS(Dirty, dirty)
162 TAS_BUFFER_FNS(Dirty, dirty)
163 BUFFER_FNS(Lock, locked)
165 TAS_BUFFER_FNS(Req, req)
166 BUFFER_FNS(Mapped, mapped)
168 BUFFER_FNS(Async_Read, async_read)
169 BUFFER_FNS(Async_Write, async_write)
170 BUFFER_FNS(Delay, delay)
171 BUFFER_FNS(Boundary, boundary)
172 BUFFER_FNS(Write_EIO, write_io_error)
173 BUFFER_FNS(Unwritten, unwritten)
174 BUFFER_FNS(Meta, meta)
175 BUFFER_FNS(Prio, prio)
176 BUFFER_FNS(Defer_Completion, defer_completion)
178 #define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK)
180 /* If we *know* page->private refers to buffer_heads */
181 #define page_buffers(page) \
183 BUG_ON(!PagePrivate(page)); \
184 ((struct buffer_head *)page_private(page)); \
186 #define page_has_buffers(page) PagePrivate(page)
188 void buffer_check_dirty_writeback(struct page *page,
189 bool *dirty, bool *writeback);
195 void mark_buffer_dirty(struct buffer_head *bh);
196 void init_buffer(struct buffer_head *, bh_end_io_t *, void *);
197 void touch_buffer(struct buffer_head *bh);
198 void set_bh_page(struct buffer_head *bh,
199 struct page *page, unsigned long offset);
200 int try_to_free_buffers(struct page *);
201 struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
203 void create_empty_buffers(struct page *, unsigned long,
204 unsigned long b_state);
205 void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
206 void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
207 void end_buffer_async_write(struct buffer_head *bh, int uptodate);
209 /* Things to do with buffers at mapping->private_list */
210 void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
211 int inode_has_buffers(struct inode *);
212 void invalidate_inode_buffers(struct inode *);
213 int remove_inode_buffers(struct inode *inode);
214 int sync_mapping_buffers(struct address_space *mapping);
215 void unmap_underlying_metadata(struct block_device *bdev, sector_t block);
217 void mark_buffer_async_write(struct buffer_head *bh);
218 void __wait_on_buffer(struct buffer_head *);
219 wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
220 struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block,
222 struct buffer_head *__getblk_gfp(struct block_device *bdev, sector_t block,
223 unsigned size, gfp_t gfp);
224 void __brelse(struct buffer_head *);
225 void __bforget(struct buffer_head *);
226 void __breadahead(struct block_device *, sector_t block, unsigned int size);
227 struct buffer_head *__bread_gfp(struct block_device *,
228 sector_t block, unsigned size, gfp_t gfp);
229 void invalidate_bh_lrus(void);
230 struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
231 void free_buffer_head(struct buffer_head * bh);
232 void unlock_buffer(struct buffer_head *bh);
233 void __lock_buffer(struct buffer_head *bh);
234 void ll_rw_block(int, int, struct buffer_head * bh[]);
235 int sync_dirty_buffer(struct buffer_head *bh);
236 int __sync_dirty_buffer(struct buffer_head *bh, int rw);
237 void write_dirty_buffer(struct buffer_head *bh, int rw);
238 int _submit_bh(int rw, struct buffer_head *bh, unsigned long bio_flags);
239 int submit_bh(int, struct buffer_head *);
240 void write_boundary_block(struct block_device *bdev,
241 sector_t bblock, unsigned blocksize);
242 int bh_uptodate_or_lock(struct buffer_head *bh);
243 int bh_submit_read(struct buffer_head *bh);
245 extern int buffer_heads_over_limit;
248 * Generic address_space_operations implementations for buffer_head-backed
251 void block_invalidatepage(struct page *page, unsigned int offset,
252 unsigned int length);
253 int block_write_full_page(struct page *page, get_block_t *get_block,
254 struct writeback_control *wbc);
255 int block_read_full_page(struct page*, get_block_t*);
256 int block_is_partially_uptodate(struct page *page, unsigned long from,
257 unsigned long count);
258 int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
259 unsigned flags, struct page **pagep, get_block_t *get_block);
260 int __block_write_begin(struct page *page, loff_t pos, unsigned len,
261 get_block_t *get_block);
262 int block_write_end(struct file *, struct address_space *,
263 loff_t, unsigned, unsigned,
264 struct page *, void *);
265 int generic_write_end(struct file *, struct address_space *,
266 loff_t, unsigned, unsigned,
267 struct page *, void *);
268 void page_zero_new_buffers(struct page *page, unsigned from, unsigned to);
269 int cont_write_begin(struct file *, struct address_space *, loff_t,
270 unsigned, unsigned, struct page **, void **,
271 get_block_t *, loff_t *);
272 int generic_cont_expand_simple(struct inode *inode, loff_t size);
273 int block_commit_write(struct page *page, unsigned from, unsigned to);
274 int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
275 get_block_t get_block);
276 int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
277 get_block_t get_block);
278 /* Convert errno to return value from ->page_mkwrite() call */
279 static inline int block_page_mkwrite_return(int err)
282 return VM_FAULT_LOCKED;
284 return VM_FAULT_NOPAGE;
288 return VM_FAULT_RETRY;
289 /* -ENOSPC, -EDQUOT, -EIO ... */
290 return VM_FAULT_SIGBUS;
292 sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
293 int block_truncate_page(struct address_space *, loff_t, get_block_t *);
294 int nobh_write_begin(struct address_space *, loff_t, unsigned, unsigned,
295 struct page **, void **, get_block_t*);
296 int nobh_write_end(struct file *, struct address_space *,
297 loff_t, unsigned, unsigned,
298 struct page *, void *);
299 int nobh_truncate_page(struct address_space *, loff_t, get_block_t *);
300 int nobh_writepage(struct page *page, get_block_t *get_block,
301 struct writeback_control *wbc);
303 void buffer_init(void);
309 static inline void attach_page_buffers(struct page *page,
310 struct buffer_head *head)
312 page_cache_get(page);
313 SetPagePrivate(page);
314 set_page_private(page, (unsigned long)head);
317 static inline void get_bh(struct buffer_head *bh)
319 atomic_inc(&bh->b_count);
322 static inline void put_bh(struct buffer_head *bh)
324 smp_mb__before_atomic();
325 atomic_dec(&bh->b_count);
328 static inline void brelse(struct buffer_head *bh)
334 static inline void bforget(struct buffer_head *bh)
340 static inline struct buffer_head *
341 sb_bread(struct super_block *sb, sector_t block)
343 return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
346 static inline struct buffer_head *
347 sb_bread_unmovable(struct super_block *sb, sector_t block)
349 return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, 0);
353 sb_breadahead(struct super_block *sb, sector_t block)
355 __breadahead(sb->s_bdev, block, sb->s_blocksize);
358 static inline struct buffer_head *
359 sb_getblk(struct super_block *sb, sector_t block)
361 return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
365 static inline struct buffer_head *
366 sb_getblk_gfp(struct super_block *sb, sector_t block, gfp_t gfp)
368 return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, gfp);
371 static inline struct buffer_head *
372 sb_find_get_block(struct super_block *sb, sector_t block)
374 return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
378 map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
380 set_buffer_mapped(bh);
381 bh->b_bdev = sb->s_bdev;
382 bh->b_blocknr = block;
383 bh->b_size = sb->s_blocksize;
386 static inline void wait_on_buffer(struct buffer_head *bh)
389 if (buffer_locked(bh))
390 __wait_on_buffer(bh);
393 static inline int trylock_buffer(struct buffer_head *bh)
395 return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));
398 static inline void lock_buffer(struct buffer_head *bh)
401 if (!trylock_buffer(bh))
405 static inline struct buffer_head *getblk_unmovable(struct block_device *bdev,
409 return __getblk_gfp(bdev, block, size, 0);
412 static inline struct buffer_head *__getblk(struct block_device *bdev,
416 return __getblk_gfp(bdev, block, size, __GFP_MOVABLE);
420 * __bread() - reads a specified block and returns the bh
421 * @bdev: the block_device to read from
422 * @block: number of block
423 * @size: size (in bytes) to read
425 * Reads a specified block, and returns buffer head that contains it.
426 * The page cache is allocated from movable area so that it can be migrated.
427 * It returns NULL if the block was unreadable.
429 static inline struct buffer_head *
430 __bread(struct block_device *bdev, sector_t block, unsigned size)
432 return __bread_gfp(bdev, block, size, __GFP_MOVABLE);
435 extern int __set_page_dirty_buffers(struct page *page);
437 #else /* CONFIG_BLOCK */
439 static inline void buffer_init(void) {}
440 static inline int try_to_free_buffers(struct page *page) { return 1; }
441 static inline int inode_has_buffers(struct inode *inode) { return 0; }
442 static inline void invalidate_inode_buffers(struct inode *inode) {}
443 static inline int remove_inode_buffers(struct inode *inode) { return 1; }
444 static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
446 #endif /* CONFIG_BLOCK */
447 #endif /* _LINUX_BUFFER_HEAD_H */