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 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_Eopnotsupp, /* operation not supported (barrier) */ 36 BH_Unwritten, /* Buffer is allocated on disk but not written */ 37 BH_Quiet, /* Buffer Error Prinks to be quiet */ 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 46struct page; 47struct buffer_head; 48struct address_space; 49typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate); 50 51/* 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). 59 */ 60struct buffer_head { 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 */ 64 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 */ 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 */ 73 struct address_space *b_assoc_map; /* mapping this buffer is 74 associated with */ 75 atomic_t b_count; /* users using this buffer_head */ 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) \ 83static inline void set_buffer_##name(struct buffer_head *bh) \ 84{ \ 85 set_bit(BH_##bit, &(bh)->b_state); \ 86} \ 87static inline void clear_buffer_##name(struct buffer_head *bh) \ 88{ \ 89 clear_bit(BH_##bit, &(bh)->b_state); \ 90} \ 91static 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) \ 100static inline int test_set_buffer_##name(struct buffer_head *bh) \ 101{ \ 102 return test_and_set_bit(BH_##bit, &(bh)->b_state); \ 103} \ 104static 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 */ 114BUFFER_FNS(Uptodate, uptodate) 115BUFFER_FNS(Dirty, dirty) 116TAS_BUFFER_FNS(Dirty, dirty) 117BUFFER_FNS(Lock, locked) 118BUFFER_FNS(Req, req) 119TAS_BUFFER_FNS(Req, req) 120BUFFER_FNS(Mapped, mapped) 121BUFFER_FNS(New, new) 122BUFFER_FNS(Async_Read, async_read) 123BUFFER_FNS(Async_Write, async_write) 124BUFFER_FNS(Delay, delay) 125BUFFER_FNS(Boundary, boundary) 126BUFFER_FNS(Write_EIO, write_io_error) 127BUFFER_FNS(Eopnotsupp, eopnotsupp) 128BUFFER_FNS(Unwritten, unwritten) 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 145void mark_buffer_dirty(struct buffer_head *bh); 146void init_buffer(struct buffer_head *, bh_end_io_t *, void *); 147void set_bh_page(struct buffer_head *bh, 148 struct page *page, unsigned long offset); 149int try_to_free_buffers(struct page *); 150struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, 151 int retry); 152void create_empty_buffers(struct page *, unsigned long, 153 unsigned long b_state); 154void end_buffer_read_sync(struct buffer_head *bh, int uptodate); 155void end_buffer_write_sync(struct buffer_head *bh, int uptodate); 156void end_buffer_async_write(struct buffer_head *bh, int uptodate); 157 158/* Things to do with buffers at mapping->private_list */ 159void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode); 160int inode_has_buffers(struct inode *); 161void invalidate_inode_buffers(struct inode *); 162int remove_inode_buffers(struct inode *inode); 163int sync_mapping_buffers(struct address_space *mapping); 164void unmap_underlying_metadata(struct block_device *bdev, sector_t block); 165 166void mark_buffer_async_write(struct buffer_head *bh); 167void __wait_on_buffer(struct buffer_head *); 168wait_queue_head_t *bh_waitq_head(struct buffer_head *bh); 169struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block, 170 unsigned size); 171struct buffer_head *__getblk(struct block_device *bdev, sector_t block, 172 unsigned size); 173void __brelse(struct buffer_head *); 174void __bforget(struct buffer_head *); 175void __breadahead(struct block_device *, sector_t block, unsigned int size); 176struct buffer_head *__bread(struct block_device *, sector_t block, unsigned size); 177void invalidate_bh_lrus(void); 178struct buffer_head *alloc_buffer_head(gfp_t gfp_flags); 179void free_buffer_head(struct buffer_head * bh); 180void unlock_buffer(struct buffer_head *bh); 181void __lock_buffer(struct buffer_head *bh); 182void ll_rw_block(int, int, struct buffer_head * bh[]); 183int sync_dirty_buffer(struct buffer_head *bh); 184int __sync_dirty_buffer(struct buffer_head *bh, int rw); 185void write_dirty_buffer(struct buffer_head *bh, int rw); 186int submit_bh(int, struct buffer_head *); 187void write_boundary_block(struct block_device *bdev, 188 sector_t bblock, unsigned blocksize); 189int bh_uptodate_or_lock(struct buffer_head *bh); 190int bh_submit_read(struct buffer_head *bh); 191 192extern int buffer_heads_over_limit; 193 194/* 195 * Generic address_space_operations implementations for buffer_head-backed 196 * address_spaces. 197 */ 198void block_invalidatepage(struct page *page, unsigned long offset); 199int block_write_full_page(struct page *page, get_block_t *get_block, 200 struct writeback_control *wbc); 201int block_write_full_page_endio(struct page *page, get_block_t *get_block, 202 struct writeback_control *wbc, bh_end_io_t *handler); 203int block_read_full_page(struct page*, get_block_t*); 204int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc, 205 unsigned long from); 206int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len, 207 unsigned flags, struct page **pagep, get_block_t *get_block); 208int __block_write_begin(struct page *page, loff_t pos, unsigned len, 209 get_block_t *get_block); 210int block_write_end(struct file *, struct address_space *, 211 loff_t, unsigned, unsigned, 212 struct page *, void *); 213int generic_write_end(struct file *, struct address_space *, 214 loff_t, unsigned, unsigned, 215 struct page *, void *); 216void page_zero_new_buffers(struct page *page, unsigned from, unsigned to); 217int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*); 218int cont_write_begin(struct file *, struct address_space *, loff_t, 219 unsigned, unsigned, struct page **, void **, 220 get_block_t *, loff_t *); 221int generic_cont_expand_simple(struct inode *inode, loff_t size); 222int block_commit_write(struct page *page, unsigned from, unsigned to); 223int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, 224 get_block_t get_block); 225void block_sync_page(struct page *); 226sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *); 227int block_truncate_page(struct address_space *, loff_t, get_block_t *); 228int nobh_write_begin(struct address_space *, loff_t, unsigned, unsigned, 229 struct page **, void **, get_block_t*); 230int nobh_write_end(struct file *, struct address_space *, 231 loff_t, unsigned, unsigned, 232 struct page *, void *); 233int nobh_truncate_page(struct address_space *, loff_t, get_block_t *); 234int nobh_writepage(struct page *page, get_block_t *get_block, 235 struct writeback_control *wbc); 236 237void buffer_init(void); 238 239/* 240 * inline definitions 241 */ 242 243static inline void attach_page_buffers(struct page *page, 244 struct buffer_head *head) 245{ 246 page_cache_get(page); 247 SetPagePrivate(page); 248 set_page_private(page, (unsigned long)head); 249} 250 251static inline void get_bh(struct buffer_head *bh) 252{ 253 atomic_inc(&bh->b_count); 254} 255 256static inline void put_bh(struct buffer_head *bh) 257{ 258 smp_mb__before_atomic_dec(); 259 atomic_dec(&bh->b_count); 260} 261 262static inline void brelse(struct buffer_head *bh) 263{ 264 if (bh) 265 __brelse(bh); 266} 267 268static inline void bforget(struct buffer_head *bh) 269{ 270 if (bh) 271 __bforget(bh); 272} 273 274static inline struct buffer_head * 275sb_bread(struct super_block *sb, sector_t block) 276{ 277 return __bread(sb->s_bdev, block, sb->s_blocksize); 278} 279 280static inline void 281sb_breadahead(struct super_block *sb, sector_t block) 282{ 283 __breadahead(sb->s_bdev, block, sb->s_blocksize); 284} 285 286static inline struct buffer_head * 287sb_getblk(struct super_block *sb, sector_t block) 288{ 289 return __getblk(sb->s_bdev, block, sb->s_blocksize); 290} 291 292static inline struct buffer_head * 293sb_find_get_block(struct super_block *sb, sector_t block) 294{ 295 return __find_get_block(sb->s_bdev, block, sb->s_blocksize); 296} 297 298static inline void 299map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block) 300{ 301 set_buffer_mapped(bh); 302 bh->b_bdev = sb->s_bdev; 303 bh->b_blocknr = block; 304 bh->b_size = sb->s_blocksize; 305} 306 307static inline void wait_on_buffer(struct buffer_head *bh) 308{ 309 might_sleep(); 310 if (buffer_locked(bh)) 311 __wait_on_buffer(bh); 312} 313 314static inline int trylock_buffer(struct buffer_head *bh) 315{ 316 return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state)); 317} 318 319static inline void lock_buffer(struct buffer_head *bh) 320{ 321 might_sleep(); 322 if (!trylock_buffer(bh)) 323 __lock_buffer(bh); 324} 325 326extern int __set_page_dirty_buffers(struct page *page); 327 328#else /* CONFIG_BLOCK */ 329 330static inline void buffer_init(void) {} 331static inline int try_to_free_buffers(struct page *page) { return 1; } 332static inline int inode_has_buffers(struct inode *inode) { return 0; } 333static inline void invalidate_inode_buffers(struct inode *inode) {} 334static inline int remove_inode_buffers(struct inode *inode) { return 1; } 335static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; } 336 337#endif /* CONFIG_BLOCK */ 338#endif /* _LINUX_BUFFER_HEAD_H */ 339