| 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 <linux/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_Unwritten, /* Buffer is allocated on disk but not written */ |
| 36 | BH_Quiet, /* Buffer Error Prinks to be quiet */ |
| 37 | BH_Meta, /* Buffer contains metadata */ |
| 38 | BH_Prio, /* Buffer should be submitted with REQ_PRIO */ |
| 39 | BH_Defer_Completion, /* Defer AIO completion to workqueue */ |
| 40 | |
| 41 | BH_PrivateStart,/* not a state bit, but the first bit available |
| 42 | * for private allocation by other entities |
| 43 | */ |
| 44 | }; |
| 45 | |
| 46 | #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512) |
| 47 | |
| 48 | struct page; |
| 49 | struct buffer_head; |
| 50 | struct address_space; |
| 51 | typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate); |
| 52 | |
| 53 | /* |
| 54 | * Historically, a buffer_head was used to map a single block |
| 55 | * within a page, and of course as the unit of I/O through the |
| 56 | * filesystem and block layers. Nowadays the basic I/O unit |
| 57 | * is the bio, and buffer_heads are used for extracting block |
| 58 | * mappings (via a get_block_t call), for tracking state within |
| 59 | * a page (via a page_mapping) and for wrapping bio submission |
| 60 | * for backward compatibility reasons (e.g. submit_bh). |
| 61 | */ |
| 62 | struct buffer_head { |
| 63 | unsigned long b_state; /* buffer state bitmap (see above) */ |
| 64 | struct buffer_head *b_this_page;/* circular list of page's buffers */ |
| 65 | struct page *b_page; /* the page this bh is mapped to */ |
| 66 | |
| 67 | sector_t b_blocknr; /* start block number */ |
| 68 | size_t b_size; /* size of mapping */ |
| 69 | char *b_data; /* pointer to data within the page */ |
| 70 | |
| 71 | struct block_device *b_bdev; |
| 72 | bh_end_io_t *b_end_io; /* I/O completion */ |
| 73 | void *b_private; /* reserved for b_end_io */ |
| 74 | struct list_head b_assoc_buffers; /* associated with another mapping */ |
| 75 | struct address_space *b_assoc_map; /* mapping this buffer is |
| 76 | associated with */ |
| 77 | atomic_t b_count; /* users using this buffer_head */ |
| 78 | }; |
| 79 | |
| 80 | /* |
| 81 | * macro tricks to expand the set_buffer_foo(), clear_buffer_foo() |
| 82 | * and buffer_foo() functions. |
| 83 | */ |
| 84 | #define BUFFER_FNS(bit, name) \ |
| 85 | static inline void set_buffer_##name(struct buffer_head *bh) \ |
| 86 | { \ |
| 87 | set_bit(BH_##bit, &(bh)->b_state); \ |
| 88 | } \ |
| 89 | static inline void clear_buffer_##name(struct buffer_head *bh) \ |
| 90 | { \ |
| 91 | clear_bit(BH_##bit, &(bh)->b_state); \ |
| 92 | } \ |
| 93 | static inline int buffer_##name(const struct buffer_head *bh) \ |
| 94 | { \ |
| 95 | return test_bit(BH_##bit, &(bh)->b_state); \ |
| 96 | } |
| 97 | |
| 98 | /* |
| 99 | * test_set_buffer_foo() and test_clear_buffer_foo() |
| 100 | */ |
| 101 | #define TAS_BUFFER_FNS(bit, name) \ |
| 102 | static inline int test_set_buffer_##name(struct buffer_head *bh) \ |
| 103 | { \ |
| 104 | return test_and_set_bit(BH_##bit, &(bh)->b_state); \ |
| 105 | } \ |
| 106 | static inline int test_clear_buffer_##name(struct buffer_head *bh) \ |
| 107 | { \ |
| 108 | return test_and_clear_bit(BH_##bit, &(bh)->b_state); \ |
| 109 | } \ |
| 110 | |
| 111 | /* |
| 112 | * Emit the buffer bitops functions. Note that there are also functions |
| 113 | * of the form "mark_buffer_foo()". These are higher-level functions which |
| 114 | * do something in addition to setting a b_state bit. |
| 115 | */ |
| 116 | BUFFER_FNS(Uptodate, uptodate) |
| 117 | BUFFER_FNS(Dirty, dirty) |
| 118 | TAS_BUFFER_FNS(Dirty, dirty) |
| 119 | BUFFER_FNS(Lock, locked) |
| 120 | BUFFER_FNS(Req, req) |
| 121 | TAS_BUFFER_FNS(Req, req) |
| 122 | BUFFER_FNS(Mapped, mapped) |
| 123 | BUFFER_FNS(New, new) |
| 124 | BUFFER_FNS(Async_Read, async_read) |
| 125 | BUFFER_FNS(Async_Write, async_write) |
| 126 | BUFFER_FNS(Delay, delay) |
| 127 | BUFFER_FNS(Boundary, boundary) |
| 128 | BUFFER_FNS(Write_EIO, write_io_error) |
| 129 | BUFFER_FNS(Unwritten, unwritten) |
| 130 | BUFFER_FNS(Meta, meta) |
| 131 | BUFFER_FNS(Prio, prio) |
| 132 | BUFFER_FNS(Defer_Completion, defer_completion) |
| 133 | |
| 134 | #define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK) |
| 135 | |
| 136 | /* If we *know* page->private refers to buffer_heads */ |
| 137 | #define page_buffers(page) \ |
| 138 | ({ \ |
| 139 | BUG_ON(!PagePrivate(page)); \ |
| 140 | ((struct buffer_head *)page_private(page)); \ |
| 141 | }) |
| 142 | #define page_has_buffers(page) PagePrivate(page) |
| 143 | |
| 144 | void buffer_check_dirty_writeback(struct page *page, |
| 145 | bool *dirty, bool *writeback); |
| 146 | |
| 147 | /* |
| 148 | * Declarations |
| 149 | */ |
| 150 | |
| 151 | void mark_buffer_dirty(struct buffer_head *bh); |
| 152 | void init_buffer(struct buffer_head *, bh_end_io_t *, void *); |
| 153 | void touch_buffer(struct buffer_head *bh); |
| 154 | void set_bh_page(struct buffer_head *bh, |
| 155 | struct page *page, unsigned long offset); |
| 156 | int try_to_free_buffers(struct page *); |
| 157 | struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, |
| 158 | int retry); |
| 159 | void create_empty_buffers(struct page *, unsigned long, |
| 160 | unsigned long b_state); |
| 161 | void end_buffer_read_sync(struct buffer_head *bh, int uptodate); |
| 162 | void end_buffer_write_sync(struct buffer_head *bh, int uptodate); |
| 163 | void end_buffer_async_write(struct buffer_head *bh, int uptodate); |
| 164 | |
| 165 | /* Things to do with buffers at mapping->private_list */ |
| 166 | void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode); |
| 167 | int inode_has_buffers(struct inode *); |
| 168 | void invalidate_inode_buffers(struct inode *); |
| 169 | int remove_inode_buffers(struct inode *inode); |
| 170 | int sync_mapping_buffers(struct address_space *mapping); |
| 171 | void unmap_underlying_metadata(struct block_device *bdev, sector_t block); |
| 172 | |
| 173 | void mark_buffer_async_write(struct buffer_head *bh); |
| 174 | void __wait_on_buffer(struct buffer_head *); |
| 175 | wait_queue_head_t *bh_waitq_head(struct buffer_head *bh); |
| 176 | struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block, |
| 177 | unsigned size); |
| 178 | struct buffer_head *__getblk(struct block_device *bdev, sector_t block, |
| 179 | unsigned size); |
| 180 | void __brelse(struct buffer_head *); |
| 181 | void __bforget(struct buffer_head *); |
| 182 | void __breadahead(struct block_device *, sector_t block, unsigned int size); |
| 183 | struct buffer_head *__bread(struct block_device *, sector_t block, unsigned size); |
| 184 | void invalidate_bh_lrus(void); |
| 185 | struct buffer_head *alloc_buffer_head(gfp_t gfp_flags); |
| 186 | void free_buffer_head(struct buffer_head * bh); |
| 187 | void unlock_buffer(struct buffer_head *bh); |
| 188 | void __lock_buffer(struct buffer_head *bh); |
| 189 | void ll_rw_block(int, int, struct buffer_head * bh[]); |
| 190 | int sync_dirty_buffer(struct buffer_head *bh); |
| 191 | int __sync_dirty_buffer(struct buffer_head *bh, int rw); |
| 192 | void write_dirty_buffer(struct buffer_head *bh, int rw); |
| 193 | int _submit_bh(int rw, struct buffer_head *bh, unsigned long bio_flags); |
| 194 | int submit_bh(int, struct buffer_head *); |
| 195 | void write_boundary_block(struct block_device *bdev, |
| 196 | sector_t bblock, unsigned blocksize); |
| 197 | int bh_uptodate_or_lock(struct buffer_head *bh); |
| 198 | int bh_submit_read(struct buffer_head *bh); |
| 199 | |
| 200 | extern int buffer_heads_over_limit; |
| 201 | |
| 202 | /* |
| 203 | * Generic address_space_operations implementations for buffer_head-backed |
| 204 | * address_spaces. |
| 205 | */ |
| 206 | void block_invalidatepage(struct page *page, unsigned int offset, |
| 207 | unsigned int length); |
| 208 | int block_write_full_page(struct page *page, get_block_t *get_block, |
| 209 | struct writeback_control *wbc); |
| 210 | int block_read_full_page(struct page*, get_block_t*); |
| 211 | int block_is_partially_uptodate(struct page *page, unsigned long from, |
| 212 | unsigned long count); |
| 213 | int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len, |
| 214 | unsigned flags, struct page **pagep, get_block_t *get_block); |
| 215 | int __block_write_begin(struct page *page, loff_t pos, unsigned len, |
| 216 | get_block_t *get_block); |
| 217 | int block_write_end(struct file *, struct address_space *, |
| 218 | loff_t, unsigned, unsigned, |
| 219 | struct page *, void *); |
| 220 | int generic_write_end(struct file *, struct address_space *, |
| 221 | loff_t, unsigned, unsigned, |
| 222 | struct page *, void *); |
| 223 | void page_zero_new_buffers(struct page *page, unsigned from, unsigned to); |
| 224 | int cont_write_begin(struct file *, struct address_space *, loff_t, |
| 225 | unsigned, unsigned, struct page **, void **, |
| 226 | get_block_t *, loff_t *); |
| 227 | int generic_cont_expand_simple(struct inode *inode, loff_t size); |
| 228 | int block_commit_write(struct page *page, unsigned from, unsigned to); |
| 229 | int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, |
| 230 | get_block_t get_block); |
| 231 | int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, |
| 232 | get_block_t get_block); |
| 233 | /* Convert errno to return value from ->page_mkwrite() call */ |
| 234 | static inline int block_page_mkwrite_return(int err) |
| 235 | { |
| 236 | if (err == 0) |
| 237 | return VM_FAULT_LOCKED; |
| 238 | if (err == -EFAULT) |
| 239 | return VM_FAULT_NOPAGE; |
| 240 | if (err == -ENOMEM) |
| 241 | return VM_FAULT_OOM; |
| 242 | if (err == -EAGAIN) |
| 243 | return VM_FAULT_RETRY; |
| 244 | /* -ENOSPC, -EDQUOT, -EIO ... */ |
| 245 | return VM_FAULT_SIGBUS; |
| 246 | } |
| 247 | sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *); |
| 248 | int block_truncate_page(struct address_space *, loff_t, get_block_t *); |
| 249 | int nobh_write_begin(struct address_space *, loff_t, unsigned, unsigned, |
| 250 | struct page **, void **, get_block_t*); |
| 251 | int nobh_write_end(struct file *, struct address_space *, |
| 252 | loff_t, unsigned, unsigned, |
| 253 | struct page *, void *); |
| 254 | int nobh_truncate_page(struct address_space *, loff_t, get_block_t *); |
| 255 | int nobh_writepage(struct page *page, get_block_t *get_block, |
| 256 | struct writeback_control *wbc); |
| 257 | |
| 258 | void buffer_init(void); |
| 259 | |
| 260 | /* |
| 261 | * inline definitions |
| 262 | */ |
| 263 | |
| 264 | static inline void attach_page_buffers(struct page *page, |
| 265 | struct buffer_head *head) |
| 266 | { |
| 267 | page_cache_get(page); |
| 268 | SetPagePrivate(page); |
| 269 | set_page_private(page, (unsigned long)head); |
| 270 | } |
| 271 | |
| 272 | static inline void get_bh(struct buffer_head *bh) |
| 273 | { |
| 274 | atomic_inc(&bh->b_count); |
| 275 | } |
| 276 | |
| 277 | static inline void put_bh(struct buffer_head *bh) |
| 278 | { |
| 279 | smp_mb__before_atomic(); |
| 280 | atomic_dec(&bh->b_count); |
| 281 | } |
| 282 | |
| 283 | static inline void brelse(struct buffer_head *bh) |
| 284 | { |
| 285 | if (bh) |
| 286 | __brelse(bh); |
| 287 | } |
| 288 | |
| 289 | static inline void bforget(struct buffer_head *bh) |
| 290 | { |
| 291 | if (bh) |
| 292 | __bforget(bh); |
| 293 | } |
| 294 | |
| 295 | static inline struct buffer_head * |
| 296 | sb_bread(struct super_block *sb, sector_t block) |
| 297 | { |
| 298 | return __bread(sb->s_bdev, block, sb->s_blocksize); |
| 299 | } |
| 300 | |
| 301 | static inline void |
| 302 | sb_breadahead(struct super_block *sb, sector_t block) |
| 303 | { |
| 304 | __breadahead(sb->s_bdev, block, sb->s_blocksize); |
| 305 | } |
| 306 | |
| 307 | static inline struct buffer_head * |
| 308 | sb_getblk(struct super_block *sb, sector_t block) |
| 309 | { |
| 310 | return __getblk(sb->s_bdev, block, sb->s_blocksize); |
| 311 | } |
| 312 | |
| 313 | static inline struct buffer_head * |
| 314 | sb_find_get_block(struct super_block *sb, sector_t block) |
| 315 | { |
| 316 | return __find_get_block(sb->s_bdev, block, sb->s_blocksize); |
| 317 | } |
| 318 | |
| 319 | static inline void |
| 320 | map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block) |
| 321 | { |
| 322 | set_buffer_mapped(bh); |
| 323 | bh->b_bdev = sb->s_bdev; |
| 324 | bh->b_blocknr = block; |
| 325 | bh->b_size = sb->s_blocksize; |
| 326 | } |
| 327 | |
| 328 | static inline void wait_on_buffer(struct buffer_head *bh) |
| 329 | { |
| 330 | might_sleep(); |
| 331 | if (buffer_locked(bh)) |
| 332 | __wait_on_buffer(bh); |
| 333 | } |
| 334 | |
| 335 | static inline int trylock_buffer(struct buffer_head *bh) |
| 336 | { |
| 337 | return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state)); |
| 338 | } |
| 339 | |
| 340 | static inline void lock_buffer(struct buffer_head *bh) |
| 341 | { |
| 342 | might_sleep(); |
| 343 | if (!trylock_buffer(bh)) |
| 344 | __lock_buffer(bh); |
| 345 | } |
| 346 | |
| 347 | extern int __set_page_dirty_buffers(struct page *page); |
| 348 | |
| 349 | #else /* CONFIG_BLOCK */ |
| 350 | |
| 351 | static inline void buffer_init(void) {} |
| 352 | static inline int try_to_free_buffers(struct page *page) { return 1; } |
| 353 | static inline int inode_has_buffers(struct inode *inode) { return 0; } |
| 354 | static inline void invalidate_inode_buffers(struct inode *inode) {} |
| 355 | static inline int remove_inode_buffers(struct inode *inode) { return 1; } |
| 356 | static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; } |
| 357 | |
| 358 | #endif /* CONFIG_BLOCK */ |
| 359 | #endif /* _LINUX_BUFFER_HEAD_H */ |