Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | |
David Howells | 9361401 | 2006-09-30 20:45:40 +0200 | [diff] [blame] | 17 | #ifdef CONFIG_BLOCK |
| 18 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 */ |
Nick Piggin | a397220 | 2005-07-07 17:56:56 -0700 | [diff] [blame] | 24 | BH_Uptodate_Lock,/* Used by the first bh in a page, to serialise |
| 25 | * IO completion of other buffers in the page |
| 26 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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) */ |
David Chinner | 33a266d | 2007-02-12 00:51:41 -0800 | [diff] [blame] | 37 | BH_Unwritten, /* Buffer is allocated on disk but not written */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 38 | |
| 39 | BH_PrivateStart,/* not a state bit, but the first bit available |
| 40 | * for private allocation by other entities |
| 41 | */ |
| 42 | }; |
| 43 | |
| 44 | #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512) |
| 45 | |
| 46 | struct page; |
| 47 | struct buffer_head; |
| 48 | struct address_space; |
| 49 | typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate); |
| 50 | |
| 51 | /* |
Badari Pulavarty | 205f87f | 2006-03-26 01:38:00 -0800 | [diff] [blame] | 52 | * Historically, a buffer_head was used to map a single block |
| 53 | * within a page, and of course as the unit of I/O through the |
| 54 | * filesystem and block layers. Nowadays the basic I/O unit |
| 55 | * is the bio, and buffer_heads are used for extracting block |
| 56 | * mappings (via a get_block_t call), for tracking state within |
| 57 | * a page (via a page_mapping) and for wrapping bio submission |
| 58 | * for backward compatibility reasons (e.g. submit_bh). |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 59 | */ |
| 60 | struct buffer_head { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 61 | unsigned long b_state; /* buffer state bitmap (see above) */ |
| 62 | struct buffer_head *b_this_page;/* circular list of page's buffers */ |
| 63 | struct page *b_page; /* the page this bh is mapped to */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 64 | |
Badari Pulavarty | 205f87f | 2006-03-26 01:38:00 -0800 | [diff] [blame] | 65 | sector_t b_blocknr; /* start block number */ |
| 66 | size_t b_size; /* size of mapping */ |
| 67 | char *b_data; /* pointer to data within the page */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 68 | |
| 69 | struct block_device *b_bdev; |
| 70 | bh_end_io_t *b_end_io; /* I/O completion */ |
| 71 | void *b_private; /* reserved for b_end_io */ |
| 72 | struct list_head b_assoc_buffers; /* associated with another mapping */ |
Jan Kara | 58ff407 | 2006-10-17 00:10:19 -0700 | [diff] [blame] | 73 | struct address_space *b_assoc_map; /* mapping this buffer is |
| 74 | associated with */ |
Badari Pulavarty | 205f87f | 2006-03-26 01:38:00 -0800 | [diff] [blame] | 75 | atomic_t b_count; /* users using this buffer_head */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 76 | }; |
| 77 | |
| 78 | /* |
| 79 | * macro tricks to expand the set_buffer_foo(), clear_buffer_foo() |
| 80 | * and buffer_foo() functions. |
| 81 | */ |
| 82 | #define BUFFER_FNS(bit, name) \ |
| 83 | static inline void set_buffer_##name(struct buffer_head *bh) \ |
| 84 | { \ |
| 85 | set_bit(BH_##bit, &(bh)->b_state); \ |
| 86 | } \ |
| 87 | static inline void clear_buffer_##name(struct buffer_head *bh) \ |
| 88 | { \ |
| 89 | clear_bit(BH_##bit, &(bh)->b_state); \ |
| 90 | } \ |
| 91 | static inline int buffer_##name(const struct buffer_head *bh) \ |
| 92 | { \ |
| 93 | return test_bit(BH_##bit, &(bh)->b_state); \ |
| 94 | } |
| 95 | |
| 96 | /* |
| 97 | * test_set_buffer_foo() and test_clear_buffer_foo() |
| 98 | */ |
| 99 | #define TAS_BUFFER_FNS(bit, name) \ |
| 100 | static inline int test_set_buffer_##name(struct buffer_head *bh) \ |
| 101 | { \ |
| 102 | return test_and_set_bit(BH_##bit, &(bh)->b_state); \ |
| 103 | } \ |
| 104 | static inline int test_clear_buffer_##name(struct buffer_head *bh) \ |
| 105 | { \ |
| 106 | return test_and_clear_bit(BH_##bit, &(bh)->b_state); \ |
| 107 | } \ |
| 108 | |
| 109 | /* |
| 110 | * Emit the buffer bitops functions. Note that there are also functions |
| 111 | * of the form "mark_buffer_foo()". These are higher-level functions which |
| 112 | * do something in addition to setting a b_state bit. |
| 113 | */ |
| 114 | BUFFER_FNS(Uptodate, uptodate) |
| 115 | BUFFER_FNS(Dirty, dirty) |
| 116 | TAS_BUFFER_FNS(Dirty, dirty) |
| 117 | BUFFER_FNS(Lock, locked) |
| 118 | TAS_BUFFER_FNS(Lock, locked) |
| 119 | BUFFER_FNS(Req, req) |
| 120 | TAS_BUFFER_FNS(Req, req) |
| 121 | BUFFER_FNS(Mapped, mapped) |
| 122 | BUFFER_FNS(New, new) |
| 123 | BUFFER_FNS(Async_Read, async_read) |
| 124 | BUFFER_FNS(Async_Write, async_write) |
| 125 | BUFFER_FNS(Delay, delay) |
| 126 | BUFFER_FNS(Boundary, boundary) |
| 127 | BUFFER_FNS(Write_EIO, write_io_error) |
| 128 | BUFFER_FNS(Ordered, ordered) |
| 129 | BUFFER_FNS(Eopnotsupp, eopnotsupp) |
David Chinner | 33a266d | 2007-02-12 00:51:41 -0800 | [diff] [blame] | 130 | BUFFER_FNS(Unwritten, unwritten) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 131 | |
| 132 | #define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK) |
| 133 | #define touch_buffer(bh) mark_page_accessed(bh->b_page) |
| 134 | |
| 135 | /* If we *know* page->private refers to buffer_heads */ |
| 136 | #define page_buffers(page) \ |
| 137 | ({ \ |
Hugh Dickins | 4c21e2f | 2005-10-29 18:16:40 -0700 | [diff] [blame] | 138 | BUG_ON(!PagePrivate(page)); \ |
| 139 | ((struct buffer_head *)page_private(page)); \ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 140 | }) |
| 141 | #define page_has_buffers(page) PagePrivate(page) |
| 142 | |
| 143 | /* |
| 144 | * Declarations |
| 145 | */ |
| 146 | |
| 147 | void FASTCALL(mark_buffer_dirty(struct buffer_head *bh)); |
| 148 | void init_buffer(struct buffer_head *, bh_end_io_t *, void *); |
| 149 | void set_bh_page(struct buffer_head *bh, |
| 150 | struct page *page, unsigned long offset); |
| 151 | int try_to_free_buffers(struct page *); |
| 152 | struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, |
| 153 | int retry); |
| 154 | void create_empty_buffers(struct page *, unsigned long, |
| 155 | unsigned long b_state); |
| 156 | void end_buffer_read_sync(struct buffer_head *bh, int uptodate); |
| 157 | void end_buffer_write_sync(struct buffer_head *bh, int uptodate); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 158 | |
| 159 | /* Things to do with buffers at mapping->private_list */ |
| 160 | void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode); |
| 161 | int inode_has_buffers(struct inode *); |
| 162 | void invalidate_inode_buffers(struct inode *); |
| 163 | int remove_inode_buffers(struct inode *inode); |
| 164 | int sync_mapping_buffers(struct address_space *mapping); |
| 165 | void unmap_underlying_metadata(struct block_device *bdev, sector_t block); |
| 166 | |
| 167 | void mark_buffer_async_write(struct buffer_head *bh); |
Peter Zijlstra | f98393a | 2007-05-06 14:49:54 -0700 | [diff] [blame] | 168 | void invalidate_bdev(struct block_device *); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 169 | int sync_blockdev(struct block_device *bdev); |
| 170 | void __wait_on_buffer(struct buffer_head *); |
| 171 | wait_queue_head_t *bh_waitq_head(struct buffer_head *bh); |
| 172 | int fsync_bdev(struct block_device *); |
| 173 | struct super_block *freeze_bdev(struct block_device *); |
| 174 | void thaw_bdev(struct block_device *, struct super_block *); |
| 175 | int fsync_super(struct super_block *); |
| 176 | int fsync_no_super(struct block_device *); |
Tomasz Kvarsin | 3991d3b | 2007-02-12 00:52:14 -0800 | [diff] [blame] | 177 | struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block, |
| 178 | unsigned size); |
| 179 | struct buffer_head *__getblk(struct block_device *bdev, sector_t block, |
| 180 | unsigned size); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 181 | void __brelse(struct buffer_head *); |
| 182 | void __bforget(struct buffer_head *); |
Tomasz Kvarsin | 3991d3b | 2007-02-12 00:52:14 -0800 | [diff] [blame] | 183 | void __breadahead(struct block_device *, sector_t block, unsigned int size); |
| 184 | struct buffer_head *__bread(struct block_device *, sector_t block, unsigned size); |
Peter Zijlstra | f9a1439 | 2007-05-06 14:49:55 -0700 | [diff] [blame] | 185 | void invalidate_bh_lrus(void); |
Al Viro | dd0fc66 | 2005-10-07 07:46:04 +0100 | [diff] [blame] | 186 | struct buffer_head *alloc_buffer_head(gfp_t gfp_flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 187 | void free_buffer_head(struct buffer_head * bh); |
| 188 | void FASTCALL(unlock_buffer(struct buffer_head *bh)); |
| 189 | void FASTCALL(__lock_buffer(struct buffer_head *bh)); |
| 190 | void ll_rw_block(int, int, struct buffer_head * bh[]); |
| 191 | int sync_dirty_buffer(struct buffer_head *bh); |
| 192 | int submit_bh(int, struct buffer_head *); |
| 193 | void write_boundary_block(struct block_device *bdev, |
| 194 | sector_t bblock, unsigned blocksize); |
| 195 | |
| 196 | extern int buffer_heads_over_limit; |
| 197 | |
| 198 | /* |
| 199 | * Generic address_space_operations implementations for buffer_head-backed |
| 200 | * address_spaces. |
| 201 | */ |
NeilBrown | 2ff28e2 | 2006-03-26 01:37:18 -0800 | [diff] [blame] | 202 | void block_invalidatepage(struct page *page, unsigned long offset); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 203 | int block_write_full_page(struct page *page, get_block_t *get_block, |
| 204 | struct writeback_control *wbc); |
| 205 | int block_read_full_page(struct page*, get_block_t*); |
Nick Piggin | afddba4 | 2007-10-16 01:25:01 -0700 | [diff] [blame^] | 206 | int block_write_begin(struct file *, struct address_space *, |
| 207 | loff_t, unsigned, unsigned, |
| 208 | struct page **, void **, get_block_t*); |
| 209 | int block_write_end(struct file *, struct address_space *, |
| 210 | loff_t, unsigned, unsigned, |
| 211 | struct page *, void *); |
| 212 | int generic_write_end(struct file *, struct address_space *, |
| 213 | loff_t, unsigned, unsigned, |
| 214 | struct page *, void *); |
| 215 | void page_zero_new_buffers(struct page *page, unsigned from, unsigned to); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 216 | int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*); |
| 217 | int cont_prepare_write(struct page*, unsigned, unsigned, get_block_t*, |
| 218 | loff_t *); |
OGAWA Hirofumi | 05eb0b5 | 2006-01-08 01:02:13 -0800 | [diff] [blame] | 219 | int generic_cont_expand(struct inode *inode, loff_t size); |
| 220 | int generic_cont_expand_simple(struct inode *inode, loff_t size); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 221 | int block_commit_write(struct page *page, unsigned from, unsigned to); |
David Chinner | 5417169 | 2007-07-19 17:39:55 +1000 | [diff] [blame] | 222 | int block_page_mkwrite(struct vm_area_struct *vma, struct page *page, |
| 223 | get_block_t get_block); |
NeilBrown | 3978d71 | 2006-03-26 01:37:17 -0800 | [diff] [blame] | 224 | void block_sync_page(struct page *); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 225 | sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *); |
| 226 | int generic_commit_write(struct file *, struct page *, unsigned, unsigned); |
| 227 | int block_truncate_page(struct address_space *, loff_t, get_block_t *); |
| 228 | int file_fsync(struct file *, struct dentry *, int); |
| 229 | int nobh_prepare_write(struct page*, unsigned, unsigned, get_block_t*); |
| 230 | int nobh_commit_write(struct file *, struct page *, unsigned, unsigned); |
| 231 | int nobh_truncate_page(struct address_space *, loff_t); |
| 232 | int nobh_writepage(struct page *page, get_block_t *get_block, |
| 233 | struct writeback_control *wbc); |
| 234 | |
Adrian Bunk | b6cd0b7 | 2006-06-27 02:53:54 -0700 | [diff] [blame] | 235 | void buffer_init(void); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 236 | |
| 237 | /* |
| 238 | * inline definitions |
| 239 | */ |
| 240 | |
| 241 | static inline void attach_page_buffers(struct page *page, |
| 242 | struct buffer_head *head) |
| 243 | { |
| 244 | page_cache_get(page); |
| 245 | SetPagePrivate(page); |
Hugh Dickins | 4c21e2f | 2005-10-29 18:16:40 -0700 | [diff] [blame] | 246 | set_page_private(page, (unsigned long)head); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 247 | } |
| 248 | |
| 249 | static inline void get_bh(struct buffer_head *bh) |
| 250 | { |
| 251 | atomic_inc(&bh->b_count); |
| 252 | } |
| 253 | |
| 254 | static inline void put_bh(struct buffer_head *bh) |
| 255 | { |
| 256 | smp_mb__before_atomic_dec(); |
| 257 | atomic_dec(&bh->b_count); |
| 258 | } |
| 259 | |
| 260 | static inline void brelse(struct buffer_head *bh) |
| 261 | { |
| 262 | if (bh) |
| 263 | __brelse(bh); |
| 264 | } |
| 265 | |
| 266 | static inline void bforget(struct buffer_head *bh) |
| 267 | { |
| 268 | if (bh) |
| 269 | __bforget(bh); |
| 270 | } |
| 271 | |
| 272 | static inline struct buffer_head * |
| 273 | sb_bread(struct super_block *sb, sector_t block) |
| 274 | { |
| 275 | return __bread(sb->s_bdev, block, sb->s_blocksize); |
| 276 | } |
| 277 | |
| 278 | static inline void |
| 279 | sb_breadahead(struct super_block *sb, sector_t block) |
| 280 | { |
| 281 | __breadahead(sb->s_bdev, block, sb->s_blocksize); |
| 282 | } |
| 283 | |
| 284 | static inline struct buffer_head * |
| 285 | sb_getblk(struct super_block *sb, sector_t block) |
| 286 | { |
| 287 | return __getblk(sb->s_bdev, block, sb->s_blocksize); |
| 288 | } |
| 289 | |
| 290 | static inline struct buffer_head * |
| 291 | sb_find_get_block(struct super_block *sb, sector_t block) |
| 292 | { |
| 293 | return __find_get_block(sb->s_bdev, block, sb->s_blocksize); |
| 294 | } |
| 295 | |
| 296 | static inline void |
| 297 | map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block) |
| 298 | { |
| 299 | set_buffer_mapped(bh); |
| 300 | bh->b_bdev = sb->s_bdev; |
| 301 | bh->b_blocknr = block; |
Badari Pulavarty | b0cf232 | 2006-03-26 01:38:00 -0800 | [diff] [blame] | 302 | bh->b_size = sb->s_blocksize; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 303 | } |
| 304 | |
| 305 | /* |
| 306 | * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into |
| 307 | * __wait_on_buffer() just to trip a debug check. Because debug code in inline |
| 308 | * functions is bloaty. |
| 309 | */ |
| 310 | static inline void wait_on_buffer(struct buffer_head *bh) |
| 311 | { |
| 312 | might_sleep(); |
| 313 | if (buffer_locked(bh) || atomic_read(&bh->b_count) == 0) |
| 314 | __wait_on_buffer(bh); |
| 315 | } |
| 316 | |
| 317 | static inline void lock_buffer(struct buffer_head *bh) |
| 318 | { |
| 319 | might_sleep(); |
| 320 | if (test_set_buffer_locked(bh)) |
| 321 | __lock_buffer(bh); |
| 322 | } |
| 323 | |
David Howells | cf9a2ae | 2006-08-29 19:05:54 +0100 | [diff] [blame] | 324 | extern int __set_page_dirty_buffers(struct page *page); |
David Howells | 9361401 | 2006-09-30 20:45:40 +0200 | [diff] [blame] | 325 | |
| 326 | #else /* CONFIG_BLOCK */ |
| 327 | |
| 328 | static inline void buffer_init(void) {} |
| 329 | static inline int try_to_free_buffers(struct page *page) { return 1; } |
| 330 | static inline int sync_blockdev(struct block_device *bdev) { return 0; } |
| 331 | static inline int inode_has_buffers(struct inode *inode) { return 0; } |
| 332 | static inline void invalidate_inode_buffers(struct inode *inode) {} |
| 333 | static inline int remove_inode_buffers(struct inode *inode) { return 1; } |
| 334 | static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; } |
Peter Zijlstra | f98393a | 2007-05-06 14:49:54 -0700 | [diff] [blame] | 335 | static inline void invalidate_bdev(struct block_device *bdev) {} |
David Howells | 9361401 | 2006-09-30 20:45:40 +0200 | [diff] [blame] | 336 | |
| 337 | |
| 338 | #endif /* CONFIG_BLOCK */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 339 | #endif /* _LINUX_BUFFER_HEAD_H */ |