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 #ifdef CONFIG_BLOCK 18 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 26 */ 27 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_Ordered, /* ordered write */ 36 BH_Eopnotsupp, /* operation not supported (barrier) */ 37 38 BH_PrivateStart,/* not a state bit, but the first bit available 39 * for private allocation by other entities 40 */ 41 }; 42 43 #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512) 44 45 struct page; 46 struct buffer_head; 47 struct address_space; 48 typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate); 49 50 /* 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). 58 */ 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 */ 63 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 */ 67 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 */ 75 }; 76 77 /* 78 * macro tricks to expand the set_buffer_foo(), clear_buffer_foo() 79 * and buffer_foo() functions. 80 */ 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); \ 93 } 94 95 /* 96 * test_set_buffer_foo() and test_clear_buffer_foo() 97 */ 98 #define TAS_BUFFER_FNS(bit, name) \ 99 static inline int test_set_buffer_##name(struct buffer_head *bh) \ 100 { \ 101 return test_and_set_bit(BH_##bit, &(bh)->b_state); \ 102 } \ 103 static inline int test_clear_buffer_##name(struct buffer_head *bh) \ 104 { \ 105 return test_and_clear_bit(BH_##bit, &(bh)->b_state); \ 106 } \ 107 108 /* 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. 112 */ 113 BUFFER_FNS(Uptodate, uptodate) 114 BUFFER_FNS(Dirty, dirty) 115 TAS_BUFFER_FNS(Dirty, dirty) 116 BUFFER_FNS(Lock, locked) 117 TAS_BUFFER_FNS(Lock, locked) 118 BUFFER_FNS(Req, req) 119 TAS_BUFFER_FNS(Req, req) 120 BUFFER_FNS(Mapped, mapped) 121 BUFFER_FNS(New, new) 122 BUFFER_FNS(Async_Read, async_read) 123 BUFFER_FNS(Async_Write, async_write) 124 BUFFER_FNS(Delay, delay) 125 BUFFER_FNS(Boundary, boundary) 126 BUFFER_FNS(Write_EIO, write_io_error) 127 BUFFER_FNS(Ordered, ordered) 128 BUFFER_FNS(Eopnotsupp, eopnotsupp) 129 130 #define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK) 131 #define touch_buffer(bh) mark_page_accessed(bh->b_page) 132 133 /* If we *know* page->private refers to buffer_heads */ 134 #define page_buffers(page) \ 135 ({ \ 136 BUG_ON(!PagePrivate(page)); \ 137 ((struct buffer_head *)page_private(page)); \ 138 }) 139 #define page_has_buffers(page) PagePrivate(page) 140 141 /* 142 * Declarations 143 */ 144 145 void FASTCALL(mark_buffer_dirty(struct buffer_head *bh)); 146 void init_buffer(struct buffer_head *, bh_end_io_t *, void *); 147 void set_bh_page(struct buffer_head *bh, 148 struct page *page, unsigned long offset); 149 int try_to_free_buffers(struct page *); 150 struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, 151 int retry); 152 void create_empty_buffers(struct page *, unsigned long, 153 unsigned long b_state); 154 void end_buffer_read_sync(struct buffer_head *bh, int uptodate); 155 void end_buffer_write_sync(struct buffer_head *bh, int uptodate); 156 157 /* Things to do with buffers at mapping->private_list */ 158 void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode); 159 int inode_has_buffers(struct inode *); 160 void invalidate_inode_buffers(struct inode *); 161 int remove_inode_buffers(struct inode *inode); 162 int sync_mapping_buffers(struct address_space *mapping); 163 void unmap_underlying_metadata(struct block_device *bdev, sector_t block); 164 165 void mark_buffer_async_write(struct buffer_head *bh); 166 void invalidate_bdev(struct block_device *, int); 167 int sync_blockdev(struct block_device *bdev); 168 void __wait_on_buffer(struct buffer_head *); 169 wait_queue_head_t *bh_waitq_head(struct buffer_head *bh); 170 int fsync_bdev(struct block_device *); 171 struct super_block *freeze_bdev(struct block_device *); 172 void thaw_bdev(struct block_device *, struct super_block *); 173 int fsync_super(struct super_block *); 174 int fsync_no_super(struct block_device *); 175 struct buffer_head *__find_get_block(struct block_device *, sector_t, int); 176 struct buffer_head * __getblk(struct block_device *, sector_t, int); 177 void __brelse(struct buffer_head *); 178 void __bforget(struct buffer_head *); 179 void __breadahead(struct block_device *, sector_t block, int size); 180 struct buffer_head *__bread(struct block_device *, sector_t block, int size); 181 struct buffer_head *alloc_buffer_head(gfp_t gfp_flags); 182 void free_buffer_head(struct buffer_head * bh); 183 void FASTCALL(unlock_buffer(struct buffer_head *bh)); 184 void FASTCALL(__lock_buffer(struct buffer_head *bh)); 185 void ll_rw_block(int, int, struct buffer_head * bh[]); 186 int sync_dirty_buffer(struct buffer_head *bh); 187 int submit_bh(int, struct buffer_head *); 188 void write_boundary_block(struct block_device *bdev, 189 sector_t bblock, unsigned blocksize); 190 191 extern int buffer_heads_over_limit; 192 193 /* 194 * Generic address_space_operations implementations for buffer_head-backed 195 * address_spaces. 196 */ 197 void block_invalidatepage(struct page *page, unsigned long offset); 198 int block_write_full_page(struct page *page, get_block_t *get_block, 199 struct writeback_control *wbc); 200 int block_read_full_page(struct page*, get_block_t*); 201 int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*); 202 int cont_prepare_write(struct page*, unsigned, unsigned, get_block_t*, 203 loff_t *); 204 int generic_cont_expand(struct inode *inode, loff_t size); 205 int generic_cont_expand_simple(struct inode *inode, loff_t size); 206 int block_commit_write(struct page *page, unsigned from, unsigned to); 207 void block_sync_page(struct page *); 208 sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *); 209 int generic_commit_write(struct file *, struct page *, unsigned, unsigned); 210 int block_truncate_page(struct address_space *, loff_t, get_block_t *); 211 int file_fsync(struct file *, struct dentry *, int); 212 int nobh_prepare_write(struct page*, unsigned, unsigned, get_block_t*); 213 int nobh_commit_write(struct file *, struct page *, unsigned, unsigned); 214 int nobh_truncate_page(struct address_space *, loff_t); 215 int nobh_writepage(struct page *page, get_block_t *get_block, 216 struct writeback_control *wbc); 217 218 void buffer_init(void); 219 220 /* 221 * inline definitions 222 */ 223 224 static inline void attach_page_buffers(struct page *page, 225 struct buffer_head *head) 226 { 227 page_cache_get(page); 228 SetPagePrivate(page); 229 set_page_private(page, (unsigned long)head); 230 } 231 232 static inline void get_bh(struct buffer_head *bh) 233 { 234 atomic_inc(&bh->b_count); 235 } 236 237 static inline void put_bh(struct buffer_head *bh) 238 { 239 smp_mb__before_atomic_dec(); 240 atomic_dec(&bh->b_count); 241 } 242 243 static inline void brelse(struct buffer_head *bh) 244 { 245 if (bh) 246 __brelse(bh); 247 } 248 249 static inline void bforget(struct buffer_head *bh) 250 { 251 if (bh) 252 __bforget(bh); 253 } 254 255 static inline struct buffer_head * 256 sb_bread(struct super_block *sb, sector_t block) 257 { 258 return __bread(sb->s_bdev, block, sb->s_blocksize); 259 } 260 261 static inline void 262 sb_breadahead(struct super_block *sb, sector_t block) 263 { 264 __breadahead(sb->s_bdev, block, sb->s_blocksize); 265 } 266 267 static inline struct buffer_head * 268 sb_getblk(struct super_block *sb, sector_t block) 269 { 270 return __getblk(sb->s_bdev, block, sb->s_blocksize); 271 } 272 273 static inline struct buffer_head * 274 sb_find_get_block(struct super_block *sb, sector_t block) 275 { 276 return __find_get_block(sb->s_bdev, block, sb->s_blocksize); 277 } 278 279 static inline void 280 map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block) 281 { 282 set_buffer_mapped(bh); 283 bh->b_bdev = sb->s_bdev; 284 bh->b_blocknr = block; 285 bh->b_size = sb->s_blocksize; 286 } 287 288 /* 289 * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into 290 * __wait_on_buffer() just to trip a debug check. Because debug code in inline 291 * functions is bloaty. 292 */ 293 static inline void wait_on_buffer(struct buffer_head *bh) 294 { 295 might_sleep(); 296 if (buffer_locked(bh) || atomic_read(&bh->b_count) == 0) 297 __wait_on_buffer(bh); 298 } 299 300 static inline void lock_buffer(struct buffer_head *bh) 301 { 302 might_sleep(); 303 if (test_set_buffer_locked(bh)) 304 __lock_buffer(bh); 305 } 306 307 extern int __set_page_dirty_buffers(struct page *page); 308 309 #else /* CONFIG_BLOCK */ 310 311 static inline void buffer_init(void) {} 312 static inline int try_to_free_buffers(struct page *page) { return 1; } 313 static inline int sync_blockdev(struct block_device *bdev) { return 0; } 314 static inline int inode_has_buffers(struct inode *inode) { return 0; } 315 static inline void invalidate_inode_buffers(struct inode *inode) {} 316 static inline int remove_inode_buffers(struct inode *inode) { return 1; } 317 static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; } 318 static inline void invalidate_bdev(struct block_device *bdev, int destroy_dirty_buffers) {} 319 320 321 #endif /* CONFIG_BLOCK */ 322 #endif /* _LINUX_BUFFER_HEAD_H */ 323