OMAPDSS: VENC: fix NULL pointer dereference in DSS2 VENC sysfs debug attr on OMAP4
[zen-stable.git] / include / linux / buffer_head.h
blob458f497738a445ec96bf2153f2e0f99ee49e3e8c
1 /*
2 * include/linux/buffer_head.h
4 * Everything to do with buffer_heads.
5 */
7 #ifndef _LINUX_BUFFER_HEAD_H
8 #define _LINUX_BUFFER_HEAD_H
10 #include <linux/types.h>
11 #include <linux/fs.h>
12 #include <linux/linkage.h>
13 #include <linux/pagemap.h>
14 #include <linux/wait.h>
15 #include <linux/atomic.h>
17 #ifdef CONFIG_BLOCK
19 enum bh_state_bits {
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 */
38 BH_PrivateStart,/* not a state bit, but the first bit available
39 * for private allocation by other entities
43 #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512)
45 struct page;
46 struct buffer_head;
47 struct address_space;
48 typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
51 * Historically, a buffer_head was used to map a single block
52 * within a page, and of course as the unit of I/O through the
53 * filesystem and block layers. Nowadays the basic I/O unit
54 * is the bio, and buffer_heads are used for extracting block
55 * mappings (via a get_block_t call), for tracking state within
56 * a page (via a page_mapping) and for wrapping bio submission
57 * for backward compatibility reasons (e.g. submit_bh).
59 struct buffer_head {
60 unsigned long b_state; /* buffer state bitmap (see above) */
61 struct buffer_head *b_this_page;/* circular list of page's buffers */
62 struct page *b_page; /* the page this bh is mapped to */
64 sector_t b_blocknr; /* start block number */
65 size_t b_size; /* size of mapping */
66 char *b_data; /* pointer to data within the page */
68 struct block_device *b_bdev;
69 bh_end_io_t *b_end_io; /* I/O completion */
70 void *b_private; /* reserved for b_end_io */
71 struct list_head b_assoc_buffers; /* associated with another mapping */
72 struct address_space *b_assoc_map; /* mapping this buffer is
73 associated with */
74 atomic_t b_count; /* users using this buffer_head */
78 * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
79 * and buffer_foo() functions.
81 #define BUFFER_FNS(bit, name) \
82 static inline void set_buffer_##name(struct buffer_head *bh) \
83 { \
84 set_bit(BH_##bit, &(bh)->b_state); \
85 } \
86 static inline void clear_buffer_##name(struct buffer_head *bh) \
87 { \
88 clear_bit(BH_##bit, &(bh)->b_state); \
89 } \
90 static inline int buffer_##name(const struct buffer_head *bh) \
91 { \
92 return test_bit(BH_##bit, &(bh)->b_state); \
96 * test_set_buffer_foo() and test_clear_buffer_foo()
98 #define TAS_BUFFER_FNS(bit, name) \
99 static inline int test_set_buffer_##name(struct buffer_head *bh) \
101 return test_and_set_bit(BH_##bit, &(bh)->b_state); \
103 static inline int test_clear_buffer_##name(struct buffer_head *bh) \
105 return test_and_clear_bit(BH_##bit, &(bh)->b_state); \
109 * Emit the buffer bitops functions. Note that there are also functions
110 * of the form "mark_buffer_foo()". These are higher-level functions which
111 * do something in addition to setting a b_state bit.
113 BUFFER_FNS(Uptodate, uptodate)
114 BUFFER_FNS(Dirty, dirty)
115 TAS_BUFFER_FNS(Dirty, dirty)
116 BUFFER_FNS(Lock, locked)
117 BUFFER_FNS(Req, req)
118 TAS_BUFFER_FNS(Req, req)
119 BUFFER_FNS(Mapped, mapped)
120 BUFFER_FNS(New, new)
121 BUFFER_FNS(Async_Read, async_read)
122 BUFFER_FNS(Async_Write, async_write)
123 BUFFER_FNS(Delay, delay)
124 BUFFER_FNS(Boundary, boundary)
125 BUFFER_FNS(Write_EIO, write_io_error)
126 BUFFER_FNS(Unwritten, unwritten)
128 #define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK)
129 #define touch_buffer(bh) mark_page_accessed(bh->b_page)
131 /* If we *know* page->private refers to buffer_heads */
132 #define page_buffers(page) \
133 ({ \
134 BUG_ON(!PagePrivate(page)); \
135 ((struct buffer_head *)page_private(page)); \
137 #define page_has_buffers(page) PagePrivate(page)
140 * Declarations
143 void mark_buffer_dirty(struct buffer_head *bh);
144 void init_buffer(struct buffer_head *, bh_end_io_t *, void *);
145 void set_bh_page(struct buffer_head *bh,
146 struct page *page, unsigned long offset);
147 int try_to_free_buffers(struct page *);
148 struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
149 int retry);
150 void create_empty_buffers(struct page *, unsigned long,
151 unsigned long b_state);
152 void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
153 void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
154 void end_buffer_async_write(struct buffer_head *bh, int uptodate);
156 /* Things to do with buffers at mapping->private_list */
157 void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
158 int inode_has_buffers(struct inode *);
159 void invalidate_inode_buffers(struct inode *);
160 int remove_inode_buffers(struct inode *inode);
161 int sync_mapping_buffers(struct address_space *mapping);
162 void unmap_underlying_metadata(struct block_device *bdev, sector_t block);
164 void mark_buffer_async_write(struct buffer_head *bh);
165 void __wait_on_buffer(struct buffer_head *);
166 wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
167 struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block,
168 unsigned size);
169 struct buffer_head *__getblk(struct block_device *bdev, sector_t block,
170 unsigned size);
171 void __brelse(struct buffer_head *);
172 void __bforget(struct buffer_head *);
173 void __breadahead(struct block_device *, sector_t block, unsigned int size);
174 struct buffer_head *__bread(struct block_device *, sector_t block, unsigned size);
175 void invalidate_bh_lrus(void);
176 struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
177 void free_buffer_head(struct buffer_head * bh);
178 void unlock_buffer(struct buffer_head *bh);
179 void __lock_buffer(struct buffer_head *bh);
180 void ll_rw_block(int, int, struct buffer_head * bh[]);
181 int sync_dirty_buffer(struct buffer_head *bh);
182 int __sync_dirty_buffer(struct buffer_head *bh, int rw);
183 void write_dirty_buffer(struct buffer_head *bh, int rw);
184 int submit_bh(int, struct buffer_head *);
185 void write_boundary_block(struct block_device *bdev,
186 sector_t bblock, unsigned blocksize);
187 int bh_uptodate_or_lock(struct buffer_head *bh);
188 int bh_submit_read(struct buffer_head *bh);
190 extern int buffer_heads_over_limit;
193 * Generic address_space_operations implementations for buffer_head-backed
194 * address_spaces.
196 void block_invalidatepage(struct page *page, unsigned long offset);
197 int block_write_full_page(struct page *page, get_block_t *get_block,
198 struct writeback_control *wbc);
199 int block_write_full_page_endio(struct page *page, get_block_t *get_block,
200 struct writeback_control *wbc, bh_end_io_t *handler);
201 int block_read_full_page(struct page*, get_block_t*);
202 int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc,
203 unsigned long from);
204 int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
205 unsigned flags, struct page **pagep, get_block_t *get_block);
206 int __block_write_begin(struct page *page, loff_t pos, unsigned len,
207 get_block_t *get_block);
208 int block_write_end(struct file *, struct address_space *,
209 loff_t, unsigned, unsigned,
210 struct page *, void *);
211 int generic_write_end(struct file *, struct address_space *,
212 loff_t, unsigned, unsigned,
213 struct page *, void *);
214 void page_zero_new_buffers(struct page *page, unsigned from, unsigned to);
215 int cont_write_begin(struct file *, struct address_space *, loff_t,
216 unsigned, unsigned, struct page **, void **,
217 get_block_t *, loff_t *);
218 int generic_cont_expand_simple(struct inode *inode, loff_t size);
219 int block_commit_write(struct page *page, unsigned from, unsigned to);
220 int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
221 get_block_t get_block);
222 int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
223 get_block_t get_block);
224 /* Convert errno to return value from ->page_mkwrite() call */
225 static inline int block_page_mkwrite_return(int err)
227 if (err == 0)
228 return VM_FAULT_LOCKED;
229 if (err == -EFAULT)
230 return VM_FAULT_NOPAGE;
231 if (err == -ENOMEM)
232 return VM_FAULT_OOM;
233 if (err == -EAGAIN)
234 return VM_FAULT_RETRY;
235 /* -ENOSPC, -EDQUOT, -EIO ... */
236 return VM_FAULT_SIGBUS;
238 sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
239 int block_truncate_page(struct address_space *, loff_t, get_block_t *);
240 int nobh_write_begin(struct address_space *, loff_t, unsigned, unsigned,
241 struct page **, void **, get_block_t*);
242 int nobh_write_end(struct file *, struct address_space *,
243 loff_t, unsigned, unsigned,
244 struct page *, void *);
245 int nobh_truncate_page(struct address_space *, loff_t, get_block_t *);
246 int nobh_writepage(struct page *page, get_block_t *get_block,
247 struct writeback_control *wbc);
249 void buffer_init(void);
252 * inline definitions
255 static inline void attach_page_buffers(struct page *page,
256 struct buffer_head *head)
258 page_cache_get(page);
259 SetPagePrivate(page);
260 set_page_private(page, (unsigned long)head);
263 static inline void get_bh(struct buffer_head *bh)
265 atomic_inc(&bh->b_count);
268 static inline void put_bh(struct buffer_head *bh)
270 smp_mb__before_atomic_dec();
271 atomic_dec(&bh->b_count);
274 static inline void brelse(struct buffer_head *bh)
276 if (bh)
277 __brelse(bh);
280 static inline void bforget(struct buffer_head *bh)
282 if (bh)
283 __bforget(bh);
286 static inline struct buffer_head *
287 sb_bread(struct super_block *sb, sector_t block)
289 return __bread(sb->s_bdev, block, sb->s_blocksize);
292 static inline void
293 sb_breadahead(struct super_block *sb, sector_t block)
295 __breadahead(sb->s_bdev, block, sb->s_blocksize);
298 static inline struct buffer_head *
299 sb_getblk(struct super_block *sb, sector_t block)
301 return __getblk(sb->s_bdev, block, sb->s_blocksize);
304 static inline struct buffer_head *
305 sb_find_get_block(struct super_block *sb, sector_t block)
307 return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
310 static inline void
311 map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
313 set_buffer_mapped(bh);
314 bh->b_bdev = sb->s_bdev;
315 bh->b_blocknr = block;
316 bh->b_size = sb->s_blocksize;
319 static inline void wait_on_buffer(struct buffer_head *bh)
321 might_sleep();
322 if (buffer_locked(bh))
323 __wait_on_buffer(bh);
326 static inline int trylock_buffer(struct buffer_head *bh)
328 return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));
331 static inline void lock_buffer(struct buffer_head *bh)
333 might_sleep();
334 if (!trylock_buffer(bh))
335 __lock_buffer(bh);
338 extern int __set_page_dirty_buffers(struct page *page);
340 #else /* CONFIG_BLOCK */
342 static inline void buffer_init(void) {}
343 static inline int try_to_free_buffers(struct page *page) { return 1; }
344 static inline int inode_has_buffers(struct inode *inode) { return 0; }
345 static inline void invalidate_inode_buffers(struct inode *inode) {}
346 static inline int remove_inode_buffers(struct inode *inode) { return 1; }
347 static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
349 #endif /* CONFIG_BLOCK */
350 #endif /* _LINUX_BUFFER_HEAD_H */