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 BH_Uptodate_Lock,/* Used by the first bh in a page, to serialise 23 * IO completion of other buffers in the page 24 */ 25 26 BH_Mapped, /* Has a disk mapping */ 27 BH_New, /* Disk mapping was newly created by get_block */ 28 BH_Async_Read, /* Is under end_buffer_async_read I/O */ 29 BH_Async_Write, /* Is under end_buffer_async_write I/O */ 30 BH_Delay, /* Buffer is not yet allocated on disk */ 31 BH_Boundary, /* Block is followed by a discontiguity */ 32 BH_Write_EIO, /* I/O error on write */ 33 BH_Ordered, /* ordered write */ 34 BH_Eopnotsupp, /* operation not supported (barrier) */ 35 36 BH_PrivateStart,/* not a state bit, but the first bit available 37 * for private allocation by other entities 38 */ 39 }; 40 41 #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512) 42 43 struct page; 44 struct buffer_head; 45 struct address_space; 46 typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate); 47 48 /* 49 * Keep related fields in common cachelines. The most commonly accessed 50 * field (b_state) goes at the start so the compiler does not generate 51 * indexed addressing for it. 52 */ 53 struct buffer_head { 54 /* First cache line: */ 55 unsigned long b_state; /* buffer state bitmap (see above) */ 56 struct buffer_head *b_this_page;/* circular list of page's buffers */ 57 struct page *b_page; /* the page this bh is mapped to */ 58 atomic_t b_count; /* users using this block */ 59 u32 b_size; /* block size */ 60 61 sector_t b_blocknr; /* block number */ 62 char *b_data; /* pointer to data block */ 63 64 struct block_device *b_bdev; 65 bh_end_io_t *b_end_io; /* I/O completion */ 66 void *b_private; /* reserved for b_end_io */ 67 struct list_head b_assoc_buffers; /* associated with another mapping */ 68 }; 69 70 /* 71 * macro tricks to expand the set_buffer_foo(), clear_buffer_foo() 72 * and buffer_foo() functions. 73 */ 74 #define BUFFER_FNS(bit, name) \ 75 static inline void set_buffer_##name(struct buffer_head *bh) \ 76 { \ 77 set_bit(BH_##bit, &(bh)->b_state); \ 78 } \ 79 static inline void clear_buffer_##name(struct buffer_head *bh) \ 80 { \ 81 clear_bit(BH_##bit, &(bh)->b_state); \ 82 } \ 83 static inline int buffer_##name(const struct buffer_head *bh) \ 84 { \ 85 return test_bit(BH_##bit, &(bh)->b_state); \ 86 } 87 88 /* 89 * test_set_buffer_foo() and test_clear_buffer_foo() 90 */ 91 #define TAS_BUFFER_FNS(bit, name) \ 92 static inline int test_set_buffer_##name(struct buffer_head *bh) \ 93 { \ 94 return test_and_set_bit(BH_##bit, &(bh)->b_state); \ 95 } \ 96 static inline int test_clear_buffer_##name(struct buffer_head *bh) \ 97 { \ 98 return test_and_clear_bit(BH_##bit, &(bh)->b_state); \ 99 } \ 100 101 /* 102 * Emit the buffer bitops functions. Note that there are also functions 103 * of the form "mark_buffer_foo()". These are higher-level functions which 104 * do something in addition to setting a b_state bit. 105 */ 106 BUFFER_FNS(Uptodate, uptodate) 107 BUFFER_FNS(Dirty, dirty) 108 TAS_BUFFER_FNS(Dirty, dirty) 109 BUFFER_FNS(Lock, locked) 110 TAS_BUFFER_FNS(Lock, locked) 111 BUFFER_FNS(Req, req) 112 TAS_BUFFER_FNS(Req, req) 113 BUFFER_FNS(Mapped, mapped) 114 BUFFER_FNS(New, new) 115 BUFFER_FNS(Async_Read, async_read) 116 BUFFER_FNS(Async_Write, async_write) 117 BUFFER_FNS(Delay, delay) 118 BUFFER_FNS(Boundary, boundary) 119 BUFFER_FNS(Write_EIO, write_io_error) 120 BUFFER_FNS(Ordered, ordered) 121 BUFFER_FNS(Eopnotsupp, eopnotsupp) 122 123 #define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK) 124 #define touch_buffer(bh) mark_page_accessed(bh->b_page) 125 126 /* If we *know* page->private refers to buffer_heads */ 127 #define page_buffers(page) \ 128 ({ \ 129 BUG_ON(!PagePrivate(page)); \ 130 ((struct buffer_head *)(page)->private); \ 131 }) 132 #define page_has_buffers(page) PagePrivate(page) 133 134 /* 135 * Declarations 136 */ 137 138 void FASTCALL(mark_buffer_dirty(struct buffer_head *bh)); 139 void init_buffer(struct buffer_head *, bh_end_io_t *, void *); 140 void set_bh_page(struct buffer_head *bh, 141 struct page *page, unsigned long offset); 142 int try_to_free_buffers(struct page *); 143 struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, 144 int retry); 145 void create_empty_buffers(struct page *, unsigned long, 146 unsigned long b_state); 147 void end_buffer_read_sync(struct buffer_head *bh, int uptodate); 148 void end_buffer_write_sync(struct buffer_head *bh, int uptodate); 149 void end_buffer_async_write(struct buffer_head *bh, int uptodate); 150 151 /* Things to do with buffers at mapping->private_list */ 152 void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode); 153 int inode_has_buffers(struct inode *); 154 void invalidate_inode_buffers(struct inode *); 155 int remove_inode_buffers(struct inode *inode); 156 int sync_mapping_buffers(struct address_space *mapping); 157 void unmap_underlying_metadata(struct block_device *bdev, sector_t block); 158 159 void mark_buffer_async_write(struct buffer_head *bh); 160 void invalidate_bdev(struct block_device *, int); 161 int sync_blockdev(struct block_device *bdev); 162 void __wait_on_buffer(struct buffer_head *); 163 wait_queue_head_t *bh_waitq_head(struct buffer_head *bh); 164 int fsync_bdev(struct block_device *); 165 struct super_block *freeze_bdev(struct block_device *); 166 void thaw_bdev(struct block_device *, struct super_block *); 167 int fsync_super(struct super_block *); 168 int fsync_no_super(struct block_device *); 169 struct buffer_head *__find_get_block(struct block_device *, sector_t, int); 170 struct buffer_head * __getblk(struct block_device *, sector_t, int); 171 void __brelse(struct buffer_head *); 172 void __bforget(struct buffer_head *); 173 void __breadahead(struct block_device *, sector_t block, int size); 174 struct buffer_head *__bread(struct block_device *, sector_t block, int size); 175 struct buffer_head *alloc_buffer_head(unsigned int __nocast gfp_flags); 176 void free_buffer_head(struct buffer_head * bh); 177 void FASTCALL(unlock_buffer(struct buffer_head *bh)); 178 void FASTCALL(__lock_buffer(struct buffer_head *bh)); 179 void ll_rw_block(int, int, struct buffer_head * bh[]); 180 int sync_dirty_buffer(struct buffer_head *bh); 181 int submit_bh(int, struct buffer_head *); 182 void write_boundary_block(struct block_device *bdev, 183 sector_t bblock, unsigned blocksize); 184 185 extern int buffer_heads_over_limit; 186 187 /* 188 * Generic address_space_operations implementations for buffer_head-backed 189 * address_spaces. 190 */ 191 int try_to_release_page(struct page * page, int gfp_mask); 192 int block_invalidatepage(struct page *page, unsigned long offset); 193 int block_write_full_page(struct page *page, get_block_t *get_block, 194 struct writeback_control *wbc); 195 int block_read_full_page(struct page*, get_block_t*); 196 int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*); 197 int cont_prepare_write(struct page*, unsigned, unsigned, get_block_t*, 198 loff_t *); 199 int generic_cont_expand(struct inode *inode, loff_t size) ; 200 int block_commit_write(struct page *page, unsigned from, unsigned to); 201 int block_sync_page(struct page *); 202 sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *); 203 int generic_commit_write(struct file *, struct page *, unsigned, unsigned); 204 int block_truncate_page(struct address_space *, loff_t, get_block_t *); 205 int file_fsync(struct file *, struct dentry *, int); 206 int nobh_prepare_write(struct page*, unsigned, unsigned, get_block_t*); 207 int nobh_commit_write(struct file *, struct page *, unsigned, unsigned); 208 int nobh_truncate_page(struct address_space *, loff_t); 209 int nobh_writepage(struct page *page, get_block_t *get_block, 210 struct writeback_control *wbc); 211 212 213 /* 214 * inline definitions 215 */ 216 217 static inline void attach_page_buffers(struct page *page, 218 struct buffer_head *head) 219 { 220 page_cache_get(page); 221 SetPagePrivate(page); 222 page->private = (unsigned long)head; 223 } 224 225 static inline void get_bh(struct buffer_head *bh) 226 { 227 atomic_inc(&bh->b_count); 228 } 229 230 static inline void put_bh(struct buffer_head *bh) 231 { 232 smp_mb__before_atomic_dec(); 233 atomic_dec(&bh->b_count); 234 } 235 236 static inline void brelse(struct buffer_head *bh) 237 { 238 if (bh) 239 __brelse(bh); 240 } 241 242 static inline void bforget(struct buffer_head *bh) 243 { 244 if (bh) 245 __bforget(bh); 246 } 247 248 static inline struct buffer_head * 249 sb_bread(struct super_block *sb, sector_t block) 250 { 251 return __bread(sb->s_bdev, block, sb->s_blocksize); 252 } 253 254 static inline void 255 sb_breadahead(struct super_block *sb, sector_t block) 256 { 257 __breadahead(sb->s_bdev, block, sb->s_blocksize); 258 } 259 260 static inline struct buffer_head * 261 sb_getblk(struct super_block *sb, sector_t block) 262 { 263 return __getblk(sb->s_bdev, block, sb->s_blocksize); 264 } 265 266 static inline struct buffer_head * 267 sb_find_get_block(struct super_block *sb, sector_t block) 268 { 269 return __find_get_block(sb->s_bdev, block, sb->s_blocksize); 270 } 271 272 static inline void 273 map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block) 274 { 275 set_buffer_mapped(bh); 276 bh->b_bdev = sb->s_bdev; 277 bh->b_blocknr = block; 278 } 279 280 /* 281 * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into 282 * __wait_on_buffer() just to trip a debug check. Because debug code in inline 283 * functions is bloaty. 284 */ 285 static inline void wait_on_buffer(struct buffer_head *bh) 286 { 287 might_sleep(); 288 if (buffer_locked(bh) || atomic_read(&bh->b_count) == 0) 289 __wait_on_buffer(bh); 290 } 291 292 static inline void lock_buffer(struct buffer_head *bh) 293 { 294 might_sleep(); 295 if (test_set_buffer_locked(bh)) 296 __lock_buffer(bh); 297 } 298 299 #endif /* _LINUX_BUFFER_HEAD_H */ 300