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 19enum 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 48struct page; 49struct buffer_head; 50struct address_space; 51typedef 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 */ 62struct 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) \ 85static inline void set_buffer_##name(struct buffer_head *bh) \ 86{ \ 87 set_bit(BH_##bit, &(bh)->b_state); \ 88} \ 89static inline void clear_buffer_##name(struct buffer_head *bh) \ 90{ \ 91 clear_bit(BH_##bit, &(bh)->b_state); \ 92} \ 93static 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) \ 102static inline int test_set_buffer_##name(struct buffer_head *bh) \ 103{ \ 104 return test_and_set_bit(BH_##bit, &(bh)->b_state); \ 105} \ 106static 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 */ 116BUFFER_FNS(Uptodate, uptodate) 117BUFFER_FNS(Dirty, dirty) 118TAS_BUFFER_FNS(Dirty, dirty) 119BUFFER_FNS(Lock, locked) 120BUFFER_FNS(Req, req) 121TAS_BUFFER_FNS(Req, req) 122BUFFER_FNS(Mapped, mapped) 123BUFFER_FNS(New, new) 124BUFFER_FNS(Async_Read, async_read) 125BUFFER_FNS(Async_Write, async_write) 126BUFFER_FNS(Delay, delay) 127BUFFER_FNS(Boundary, boundary) 128BUFFER_FNS(Write_EIO, write_io_error) 129BUFFER_FNS(Unwritten, unwritten) 130BUFFER_FNS(Meta, meta) 131BUFFER_FNS(Prio, prio) 132BUFFER_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 144void buffer_check_dirty_writeback(struct page *page, 145 bool *dirty, bool *writeback); 146 147/* 148 * Declarations 149 */ 150 151void mark_buffer_dirty(struct buffer_head *bh); 152void init_buffer(struct buffer_head *, bh_end_io_t *, void *); 153void touch_buffer(struct buffer_head *bh); 154void set_bh_page(struct buffer_head *bh, 155 struct page *page, unsigned long offset); 156int try_to_free_buffers(struct page *); 157struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, 158 int retry); 159void create_empty_buffers(struct page *, unsigned long, 160 unsigned long b_state); 161void end_buffer_read_sync(struct buffer_head *bh, int uptodate); 162void end_buffer_write_sync(struct buffer_head *bh, int uptodate); 163void end_buffer_async_write(struct buffer_head *bh, int uptodate); 164 165/* Things to do with buffers at mapping->private_list */ 166void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode); 167int inode_has_buffers(struct inode *); 168void invalidate_inode_buffers(struct inode *); 169int remove_inode_buffers(struct inode *inode); 170int sync_mapping_buffers(struct address_space *mapping); 171void unmap_underlying_metadata(struct block_device *bdev, sector_t block); 172 173void mark_buffer_async_write(struct buffer_head *bh); 174void __wait_on_buffer(struct buffer_head *); 175wait_queue_head_t *bh_waitq_head(struct buffer_head *bh); 176struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block, 177 unsigned size); 178struct buffer_head *__getblk_gfp(struct block_device *bdev, sector_t block, 179 unsigned size, gfp_t gfp); 180void __brelse(struct buffer_head *); 181void __bforget(struct buffer_head *); 182void __breadahead(struct block_device *, sector_t block, unsigned int size); 183struct buffer_head *__bread_gfp(struct block_device *, 184 sector_t block, unsigned size, gfp_t gfp); 185void invalidate_bh_lrus(void); 186struct buffer_head *alloc_buffer_head(gfp_t gfp_flags); 187void free_buffer_head(struct buffer_head * bh); 188void unlock_buffer(struct buffer_head *bh); 189void __lock_buffer(struct buffer_head *bh); 190void ll_rw_block(int, int, struct buffer_head * bh[]); 191int sync_dirty_buffer(struct buffer_head *bh); 192int __sync_dirty_buffer(struct buffer_head *bh, int rw); 193void write_dirty_buffer(struct buffer_head *bh, int rw); 194int _submit_bh(int rw, struct buffer_head *bh, unsigned long bio_flags); 195int submit_bh(int, struct buffer_head *); 196void write_boundary_block(struct block_device *bdev, 197 sector_t bblock, unsigned blocksize); 198int bh_uptodate_or_lock(struct buffer_head *bh); 199int bh_submit_read(struct buffer_head *bh); 200 201extern int buffer_heads_over_limit; 202 203/* 204 * Generic address_space_operations implementations for buffer_head-backed 205 * address_spaces. 206 */ 207void block_invalidatepage(struct page *page, unsigned int offset, 208 unsigned int length); 209int block_write_full_page(struct page *page, get_block_t *get_block, 210 struct writeback_control *wbc); 211int block_read_full_page(struct page*, get_block_t*); 212int block_is_partially_uptodate(struct page *page, unsigned long from, 213 unsigned long count); 214int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len, 215 unsigned flags, struct page **pagep, get_block_t *get_block); 216int __block_write_begin(struct page *page, loff_t pos, unsigned len, 217 get_block_t *get_block); 218int block_write_end(struct file *, struct address_space *, 219 loff_t, unsigned, unsigned, 220 struct page *, void *); 221int generic_write_end(struct file *, struct address_space *, 222 loff_t, unsigned, unsigned, 223 struct page *, void *); 224void page_zero_new_buffers(struct page *page, unsigned from, unsigned to); 225int cont_write_begin(struct file *, struct address_space *, loff_t, 226 unsigned, unsigned, struct page **, void **, 227 get_block_t *, loff_t *); 228int generic_cont_expand_simple(struct inode *inode, loff_t size); 229int block_commit_write(struct page *page, unsigned from, unsigned to); 230int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, 231 get_block_t get_block); 232/* Convert errno to return value from ->page_mkwrite() call */ 233static inline int block_page_mkwrite_return(int err) 234{ 235 if (err == 0) 236 return VM_FAULT_LOCKED; 237 if (err == -EFAULT) 238 return VM_FAULT_NOPAGE; 239 if (err == -ENOMEM) 240 return VM_FAULT_OOM; 241 if (err == -EAGAIN) 242 return VM_FAULT_RETRY; 243 /* -ENOSPC, -EDQUOT, -EIO ... */ 244 return VM_FAULT_SIGBUS; 245} 246sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *); 247int block_truncate_page(struct address_space *, loff_t, get_block_t *); 248int nobh_write_begin(struct address_space *, loff_t, unsigned, unsigned, 249 struct page **, void **, get_block_t*); 250int nobh_write_end(struct file *, struct address_space *, 251 loff_t, unsigned, unsigned, 252 struct page *, void *); 253int nobh_truncate_page(struct address_space *, loff_t, get_block_t *); 254int nobh_writepage(struct page *page, get_block_t *get_block, 255 struct writeback_control *wbc); 256 257void buffer_init(void); 258 259/* 260 * inline definitions 261 */ 262 263static inline void attach_page_buffers(struct page *page, 264 struct buffer_head *head) 265{ 266 page_cache_get(page); 267 SetPagePrivate(page); 268 set_page_private(page, (unsigned long)head); 269} 270 271static inline void get_bh(struct buffer_head *bh) 272{ 273 atomic_inc(&bh->b_count); 274} 275 276static inline void put_bh(struct buffer_head *bh) 277{ 278 smp_mb__before_atomic(); 279 atomic_dec(&bh->b_count); 280} 281 282static inline void brelse(struct buffer_head *bh) 283{ 284 if (bh) 285 __brelse(bh); 286} 287 288static inline void bforget(struct buffer_head *bh) 289{ 290 if (bh) 291 __bforget(bh); 292} 293 294static inline struct buffer_head * 295sb_bread(struct super_block *sb, sector_t block) 296{ 297 return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE); 298} 299 300static inline struct buffer_head * 301sb_bread_unmovable(struct super_block *sb, sector_t block) 302{ 303 return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, 0); 304} 305 306static inline void 307sb_breadahead(struct super_block *sb, sector_t block) 308{ 309 __breadahead(sb->s_bdev, block, sb->s_blocksize); 310} 311 312static inline struct buffer_head * 313sb_getblk(struct super_block *sb, sector_t block) 314{ 315 return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE); 316} 317 318 319static inline struct buffer_head * 320sb_getblk_gfp(struct super_block *sb, sector_t block, gfp_t gfp) 321{ 322 return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, gfp); 323} 324 325static inline struct buffer_head * 326sb_find_get_block(struct super_block *sb, sector_t block) 327{ 328 return __find_get_block(sb->s_bdev, block, sb->s_blocksize); 329} 330 331static inline void 332map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block) 333{ 334 set_buffer_mapped(bh); 335 bh->b_bdev = sb->s_bdev; 336 bh->b_blocknr = block; 337 bh->b_size = sb->s_blocksize; 338} 339 340static inline void wait_on_buffer(struct buffer_head *bh) 341{ 342 might_sleep(); 343 if (buffer_locked(bh)) 344 __wait_on_buffer(bh); 345} 346 347static inline int trylock_buffer(struct buffer_head *bh) 348{ 349 return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state)); 350} 351 352static inline void lock_buffer(struct buffer_head *bh) 353{ 354 might_sleep(); 355 if (!trylock_buffer(bh)) 356 __lock_buffer(bh); 357} 358 359static inline struct buffer_head *getblk_unmovable(struct block_device *bdev, 360 sector_t block, 361 unsigned size) 362{ 363 return __getblk_gfp(bdev, block, size, 0); 364} 365 366static inline struct buffer_head *__getblk(struct block_device *bdev, 367 sector_t block, 368 unsigned size) 369{ 370 return __getblk_gfp(bdev, block, size, __GFP_MOVABLE); 371} 372 373/** 374 * __bread() - reads a specified block and returns the bh 375 * @bdev: the block_device to read from 376 * @block: number of block 377 * @size: size (in bytes) to read 378 * 379 * Reads a specified block, and returns buffer head that contains it. 380 * The page cache is allocated from movable area so that it can be migrated. 381 * It returns NULL if the block was unreadable. 382 */ 383static inline struct buffer_head * 384__bread(struct block_device *bdev, sector_t block, unsigned size) 385{ 386 return __bread_gfp(bdev, block, size, __GFP_MOVABLE); 387} 388 389extern int __set_page_dirty_buffers(struct page *page); 390 391#else /* CONFIG_BLOCK */ 392 393static inline void buffer_init(void) {} 394static inline int try_to_free_buffers(struct page *page) { return 1; } 395static inline int inode_has_buffers(struct inode *inode) { return 0; } 396static inline void invalidate_inode_buffers(struct inode *inode) {} 397static inline int remove_inode_buffers(struct inode *inode) { return 1; } 398static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; } 399 400#endif /* CONFIG_BLOCK */ 401#endif /* _LINUX_BUFFER_HEAD_H */ 402