1 /* 2 * include/linux/buffer_head.h 3 * 4 * Everything to do with buffer_heads. 5 */ 6 7 #ifndef _LINUX_BUFFER_HEAD_H 8 #define _LINUX_BUFFER_HEAD_H 9 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 <asm/atomic.h> 16 17 enum bh_state_bits { 18 BH_Uptodate, /* Contains valid data */ 19 BH_Dirty, /* Is dirty */ 20 BH_Lock, /* Is locked */ 21 BH_Req, /* Has been submitted for I/O */ 22 23 BH_Mapped, /* Has a disk mapping */ 24 BH_New, /* Disk mapping was newly created by get_block */ 25 BH_Async_Read, /* Is under end_buffer_async_read I/O */ 26 BH_Async_Write, /* Is under end_buffer_async_write I/O */ 27 BH_Delay, /* Buffer is not yet allocated on disk */ 28 BH_Boundary, /* Block is followed by a discontiguity */ 29 BH_Write_EIO, /* I/O error on write */ 30 BH_Ordered, /* ordered write */ 31 BH_Eopnotsupp, /* operation not supported (barrier) */ 32 33 BH_PrivateStart,/* not a state bit, but the first bit available 34 * for private allocation by other entities 35 */ 36 }; 37 38 #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512) 39 40 struct page; 41 struct buffer_head; 42 struct address_space; 43 typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate); 44 45 /* 46 * Keep related fields in common cachelines. The most commonly accessed 47 * field (b_state) goes at the start so the compiler does not generate 48 * indexed addressing for it. 49 */ 50 struct buffer_head { 51 /* First cache line: */ 52 unsigned long b_state; /* buffer state bitmap (see above) */ 53 struct buffer_head *b_this_page;/* circular list of page's buffers */ 54 struct page *b_page; /* the page this bh is mapped to */ 55 atomic_t b_count; /* users using this block */ 56 u32 b_size; /* block size */ 57 58 sector_t b_blocknr; /* block number */ 59 char *b_data; /* pointer to data block */ 60 61 struct block_device *b_bdev; 62 bh_end_io_t *b_end_io; /* I/O completion */ 63 void *b_private; /* reserved for b_end_io */ 64 struct list_head b_assoc_buffers; /* associated with another mapping */ 65 }; 66 67 /* 68 * macro tricks to expand the set_buffer_foo(), clear_buffer_foo() 69 * and buffer_foo() functions. 70 */ 71 #define BUFFER_FNS(bit, name) \ 72 static inline void set_buffer_##name(struct buffer_head *bh) \ 73 { \ 74 set_bit(BH_##bit, &(bh)->b_state); \ 75 } \ 76 static inline void clear_buffer_##name(struct buffer_head *bh) \ 77 { \ 78 clear_bit(BH_##bit, &(bh)->b_state); \ 79 } \ 80 static inline int buffer_##name(const struct buffer_head *bh) \ 81 { \ 82 return test_bit(BH_##bit, &(bh)->b_state); \ 83 } 84 85 /* 86 * test_set_buffer_foo() and test_clear_buffer_foo() 87 */ 88 #define TAS_BUFFER_FNS(bit, name) \ 89 static inline int test_set_buffer_##name(struct buffer_head *bh) \ 90 { \ 91 return test_and_set_bit(BH_##bit, &(bh)->b_state); \ 92 } \ 93 static inline int test_clear_buffer_##name(struct buffer_head *bh) \ 94 { \ 95 return test_and_clear_bit(BH_##bit, &(bh)->b_state); \ 96 } \ 97 98 /* 99 * Emit the buffer bitops functions. Note that there are also functions 100 * of the form "mark_buffer_foo()". These are higher-level functions which 101 * do something in addition to setting a b_state bit. 102 */ 103 BUFFER_FNS(Uptodate, uptodate) 104 BUFFER_FNS(Dirty, dirty) 105 TAS_BUFFER_FNS(Dirty, dirty) 106 BUFFER_FNS(Lock, locked) 107 TAS_BUFFER_FNS(Lock, locked) 108 BUFFER_FNS(Req, req) 109 TAS_BUFFER_FNS(Req, req) 110 BUFFER_FNS(Mapped, mapped) 111 BUFFER_FNS(New, new) 112 BUFFER_FNS(Async_Read, async_read) 113 BUFFER_FNS(Async_Write, async_write) 114 BUFFER_FNS(Delay, delay) 115 BUFFER_FNS(Boundary, boundary) 116 BUFFER_FNS(Write_EIO, write_io_error) 117 BUFFER_FNS(Ordered, ordered) 118 BUFFER_FNS(Eopnotsupp, eopnotsupp) 119 120 #define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK) 121 #define touch_buffer(bh) mark_page_accessed(bh->b_page) 122 123 /* If we *know* page->private refers to buffer_heads */ 124 #define page_buffers(page) \ 125 ({ \ 126 BUG_ON(!PagePrivate(page)); \ 127 ((struct buffer_head *)(page)->private); \ 128 }) 129 #define page_has_buffers(page) PagePrivate(page) 130 131 /* 132 * Declarations 133 */ 134 135 void FASTCALL(mark_buffer_dirty(struct buffer_head *bh)); 136 void init_buffer(struct buffer_head *, bh_end_io_t *, void *); 137 void set_bh_page(struct buffer_head *bh, 138 struct page *page, unsigned long offset); 139 int try_to_free_buffers(struct page *); 140 struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, 141 int retry); 142 void create_empty_buffers(struct page *, unsigned long, 143 unsigned long b_state); 144 void end_buffer_read_sync(struct buffer_head *bh, int uptodate); 145 void end_buffer_write_sync(struct buffer_head *bh, int uptodate); 146 void end_buffer_async_write(struct buffer_head *bh, int uptodate); 147 148 /* Things to do with buffers at mapping->private_list */ 149 void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode); 150 int inode_has_buffers(struct inode *); 151 void invalidate_inode_buffers(struct inode *); 152 int remove_inode_buffers(struct inode *inode); 153 int sync_mapping_buffers(struct address_space *mapping); 154 void unmap_underlying_metadata(struct block_device *bdev, sector_t block); 155 156 void mark_buffer_async_write(struct buffer_head *bh); 157 void invalidate_bdev(struct block_device *, int); 158 int sync_blockdev(struct block_device *bdev); 159 void __wait_on_buffer(struct buffer_head *); 160 wait_queue_head_t *bh_waitq_head(struct buffer_head *bh); 161 int fsync_bdev(struct block_device *); 162 struct super_block *freeze_bdev(struct block_device *); 163 void thaw_bdev(struct block_device *, struct super_block *); 164 int fsync_super(struct super_block *); 165 int fsync_no_super(struct block_device *); 166 struct buffer_head *__find_get_block(struct block_device *, sector_t, int); 167 struct buffer_head * __getblk(struct block_device *, sector_t, int); 168 void __brelse(struct buffer_head *); 169 void __bforget(struct buffer_head *); 170 void __breadahead(struct block_device *, sector_t block, int size); 171 struct buffer_head *__bread(struct block_device *, sector_t block, int size); 172 struct buffer_head *alloc_buffer_head(unsigned int __nocast gfp_flags); 173 void free_buffer_head(struct buffer_head * bh); 174 void FASTCALL(unlock_buffer(struct buffer_head *bh)); 175 void FASTCALL(__lock_buffer(struct buffer_head *bh)); 176 void ll_rw_block(int, int, struct buffer_head * bh[]); 177 int sync_dirty_buffer(struct buffer_head *bh); 178 int submit_bh(int, struct buffer_head *); 179 void write_boundary_block(struct block_device *bdev, 180 sector_t bblock, unsigned blocksize); 181 182 extern int buffer_heads_over_limit; 183 184 /* 185 * Generic address_space_operations implementations for buffer_head-backed 186 * address_spaces. 187 */ 188 int try_to_release_page(struct page * page, int gfp_mask); 189 int block_invalidatepage(struct page *page, unsigned long offset); 190 int block_write_full_page(struct page *page, get_block_t *get_block, 191 struct writeback_control *wbc); 192 int block_read_full_page(struct page*, get_block_t*); 193 int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*); 194 int cont_prepare_write(struct page*, unsigned, unsigned, get_block_t*, 195 loff_t *); 196 int generic_cont_expand(struct inode *inode, loff_t size) ; 197 int block_commit_write(struct page *page, unsigned from, unsigned to); 198 int block_sync_page(struct page *); 199 sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *); 200 int generic_commit_write(struct file *, struct page *, unsigned, unsigned); 201 int block_truncate_page(struct address_space *, loff_t, get_block_t *); 202 int file_fsync(struct file *, struct dentry *, int); 203 int nobh_prepare_write(struct page*, unsigned, unsigned, get_block_t*); 204 int nobh_commit_write(struct file *, struct page *, unsigned, unsigned); 205 int nobh_truncate_page(struct address_space *, loff_t); 206 int nobh_writepage(struct page *page, get_block_t *get_block, 207 struct writeback_control *wbc); 208 209 210 /* 211 * inline definitions 212 */ 213 214 static inline void attach_page_buffers(struct page *page, 215 struct buffer_head *head) 216 { 217 page_cache_get(page); 218 SetPagePrivate(page); 219 page->private = (unsigned long)head; 220 } 221 222 static inline void get_bh(struct buffer_head *bh) 223 { 224 atomic_inc(&bh->b_count); 225 } 226 227 static inline void put_bh(struct buffer_head *bh) 228 { 229 smp_mb__before_atomic_dec(); 230 atomic_dec(&bh->b_count); 231 } 232 233 static inline void brelse(struct buffer_head *bh) 234 { 235 if (bh) 236 __brelse(bh); 237 } 238 239 static inline void bforget(struct buffer_head *bh) 240 { 241 if (bh) 242 __bforget(bh); 243 } 244 245 static inline struct buffer_head * 246 sb_bread(struct super_block *sb, sector_t block) 247 { 248 return __bread(sb->s_bdev, block, sb->s_blocksize); 249 } 250 251 static inline void 252 sb_breadahead(struct super_block *sb, sector_t block) 253 { 254 __breadahead(sb->s_bdev, block, sb->s_blocksize); 255 } 256 257 static inline struct buffer_head * 258 sb_getblk(struct super_block *sb, sector_t block) 259 { 260 return __getblk(sb->s_bdev, block, sb->s_blocksize); 261 } 262 263 static inline struct buffer_head * 264 sb_find_get_block(struct super_block *sb, sector_t block) 265 { 266 return __find_get_block(sb->s_bdev, block, sb->s_blocksize); 267 } 268 269 static inline void 270 map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block) 271 { 272 set_buffer_mapped(bh); 273 bh->b_bdev = sb->s_bdev; 274 bh->b_blocknr = block; 275 } 276 277 /* 278 * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into 279 * __wait_on_buffer() just to trip a debug check. Because debug code in inline 280 * functions is bloaty. 281 */ 282 static inline void wait_on_buffer(struct buffer_head *bh) 283 { 284 might_sleep(); 285 if (buffer_locked(bh) || atomic_read(&bh->b_count) == 0) 286 __wait_on_buffer(bh); 287 } 288 289 static inline void lock_buffer(struct buffer_head *bh) 290 { 291 might_sleep(); 292 if (test_set_buffer_locked(bh)) 293 __lock_buffer(bh); 294 } 295 296 #endif /* _LINUX_BUFFER_HEAD_H */ 297