include/linux/buffer_head.h

   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 enum bh_state_bits {
  18         BH_Uptodate,    /* Contains valid data */
  19         BH_Dirty,       /* Is dirty */
  20         BH_Lock,        /* Is locked */
  21         BH_Req,         /* Has been submitted for I/O */
  22
  23         BH_Mapped,      /* Has a disk mapping */
  24         BH_New,         /* Disk mapping was newly created by get_block */
  25         BH_Async_Read,  /* Is under end_buffer_async_read I/O */
  26         BH_Async_Write, /* Is under end_buffer_async_write I/O */
  27         BH_Delay,       /* Buffer is not yet allocated on disk */
  28         BH_Boundary,    /* Block is followed by a discontiguity */
  29         BH_Write_EIO,   /* I/O error on write */
  30         BH_Ordered,     /* ordered write */
  31         BH_Eopnotsupp,  /* operation not supported (barrier) */
  32
  33         BH_PrivateStart,/* not a state bit, but the first bit available
  34                          * for private allocation by other entities
  35                          */
  36 };
  37
  38 #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512)
  39
  40 struct page;
  41 struct buffer_head;
  42 struct address_space;
  43 typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
  44
  45 /*
  46  * Keep related fields in common cachelines.  The most commonly accessed
  47  * field (b_state) goes at the start so the compiler does not generate
  48  * indexed addressing for it.
  49  */
  50 struct buffer_head {
  51         /* First cache line: */
  52         unsigned long b_state;          /* buffer state bitmap (see above) */
  53         struct buffer_head *b_this_page;/* circular list of page's buffers */
  54         struct page *b_page;            /* the page this bh is mapped to */
  55         atomic_t b_count;               /* users using this block */
  56         u32 b_size;                     /* block size */
  57
  58         sector_t b_blocknr;             /* block number */
  59         char *b_data;                   /* pointer to data block */
  60
  61         struct block_device *b_bdev;
  62         bh_end_io_t *b_end_io;          /* I/O completion */
  63         void *b_private;                /* reserved for b_end_io */
  64         struct list_head b_assoc_buffers; /* associated with another mapping */
  65 };
  66
  67 /*
  68  * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
  69  * and buffer_foo() functions.
  70  */
  71 #define BUFFER_FNS(bit, name)                                           \
  72 static inline void set_buffer_##name(struct buffer_head *bh)            \
  73 {                                                                       \
  74         set_bit(BH_##bit, &(bh)->b_state);                              \
  75 }                                                                       \
  76 static inline void clear_buffer_##name(struct buffer_head *bh)          \
  77 {                                                                       \
  78         clear_bit(BH_##bit, &(bh)->b_state);                            \
  79 }                                                                       \
  80 static inline int buffer_##name(const struct buffer_head *bh)           \
  81 {                                                                       \
  82         return test_bit(BH_##bit, &(bh)->b_state);                      \
  83 }
  84
  85 /*
  86  * test_set_buffer_foo() and test_clear_buffer_foo()
  87  */
  88 #define TAS_BUFFER_FNS(bit, name)                                       \
  89 static inline int test_set_buffer_##name(struct buffer_head *bh)        \
  90 {                                                                       \
  91         return test_and_set_bit(BH_##bit, &(bh)->b_state);              \
  92 }                                                                       \
  93 static inline int test_clear_buffer_##name(struct buffer_head *bh)      \
  94 {                                                                       \
  95         return test_and_clear_bit(BH_##bit, &(bh)->b_state);            \
  96 }                                                                       \
  97
  98 /*
  99  * Emit the buffer bitops functions.   Note that there are also functions
 100  * of the form "mark_buffer_foo()".  These are higher-level functions which
 101  * do something in addition to setting a b_state bit.
 102  */
 103 BUFFER_FNS(Uptodate, uptodate)
 104 BUFFER_FNS(Dirty, dirty)
 105 TAS_BUFFER_FNS(Dirty, dirty)
 106 BUFFER_FNS(Lock, locked)
 107 TAS_BUFFER_FNS(Lock, locked)
 108 BUFFER_FNS(Req, req)
 109 TAS_BUFFER_FNS(Req, req)
 110 BUFFER_FNS(Mapped, mapped)
 111 BUFFER_FNS(New, new)
 112 BUFFER_FNS(Async_Read, async_read)
 113 BUFFER_FNS(Async_Write, async_write)
 114 BUFFER_FNS(Delay, delay)
 115 BUFFER_FNS(Boundary, boundary)
 116 BUFFER_FNS(Write_EIO, write_io_error)
 117 BUFFER_FNS(Ordered, ordered)
 118 BUFFER_FNS(Eopnotsupp, eopnotsupp)
 119
 120 #define bh_offset(bh)           ((unsigned long)(bh)->b_data & ~PAGE_MASK)
 121 #define touch_buffer(bh)        mark_page_accessed(bh->b_page)
 122
 123 /* If we *know* page->private refers to buffer_heads */
 124 #define page_buffers(page)                                      \
 125         ({                                                      \
 126                 BUG_ON(!PagePrivate(page));             \
 127                 ((struct buffer_head *)(page)->private);        \
 128         })
 129 #define page_has_buffers(page)  PagePrivate(page)
 130
 131 /*
 132  * Declarations
 133  */
 134
 135 void FASTCALL(mark_buffer_dirty(struct buffer_head *bh));
 136 void init_buffer(struct buffer_head *, bh_end_io_t *, void *);
 137 void set_bh_page(struct buffer_head *bh,
 138                 struct page *page, unsigned long offset);
 139 int try_to_free_buffers(struct page *);
 140 struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
 141                 int retry);
 142 void create_empty_buffers(struct page *, unsigned long,
 143                         unsigned long b_state);
 144 void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
 145 void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
 146 void end_buffer_async_write(struct buffer_head *bh, int uptodate);
 147
 148 /* Things to do with buffers at mapping->private_list */
 149 void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
 150 int inode_has_buffers(struct inode *);
 151 void invalidate_inode_buffers(struct inode *);
 152 int remove_inode_buffers(struct inode *inode);
 153 int sync_mapping_buffers(struct address_space *mapping);
 154 void unmap_underlying_metadata(struct block_device *bdev, sector_t block);
 155
 156 void mark_buffer_async_write(struct buffer_head *bh);
 157 void invalidate_bdev(struct block_device *, int);
 158 int sync_blockdev(struct block_device *bdev);
 159 void __wait_on_buffer(struct buffer_head *);
 160 wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
 161 int fsync_bdev(struct block_device *);
 162 struct super_block *freeze_bdev(struct block_device *);
 163 void thaw_bdev(struct block_device *, struct super_block *);
 164 int fsync_super(struct super_block *);
 165 int fsync_no_super(struct block_device *);
 166 struct buffer_head *__find_get_block(struct block_device *, sector_t, int);
 167 struct buffer_head * __getblk(struct block_device *, sector_t, int);
 168 void __brelse(struct buffer_head *);
 169 void __bforget(struct buffer_head *);
 170 void __breadahead(struct block_device *, sector_t block, int size);
 171 struct buffer_head *__bread(struct block_device *, sector_t block, int size);
 172 struct buffer_head *alloc_buffer_head(unsigned int __nocast gfp_flags);
 173 void free_buffer_head(struct buffer_head * bh);
 174 void FASTCALL(unlock_buffer(struct buffer_head *bh));
 175 void FASTCALL(__lock_buffer(struct buffer_head *bh));
 176 void ll_rw_block(int, int, struct buffer_head * bh[]);
 177 int sync_dirty_buffer(struct buffer_head *bh);
 178 int submit_bh(int, struct buffer_head *);
 179 void write_boundary_block(struct block_device *bdev,
 180                         sector_t bblock, unsigned blocksize);
 181
 182 extern int buffer_heads_over_limit;
 183
 184 /*
 185  * Generic address_space_operations implementations for buffer_head-backed
 186  * address_spaces.
 187  */
 188 int try_to_release_page(struct page * page, int gfp_mask);
 189 int block_invalidatepage(struct page *page, unsigned long offset);
 190 int block_write_full_page(struct page *page, get_block_t *get_block,
 191                                 struct writeback_control *wbc);
 192 int block_read_full_page(struct page*, get_block_t*);
 193 int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
 194 int cont_prepare_write(struct page*, unsigned, unsigned, get_block_t*,
 195                                 loff_t *);
 196 int generic_cont_expand(struct inode *inode, loff_t size) ;
 197 int block_commit_write(struct page *page, unsigned from, unsigned to);
 198 int block_sync_page(struct page *);
 199 sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
 200 int generic_commit_write(struct file *, struct page *, unsigned, unsigned);
 201 int block_truncate_page(struct address_space *, loff_t, get_block_t *);
 202 int file_fsync(struct file *, struct dentry *, int);
 203 int nobh_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
 204 int nobh_commit_write(struct file *, struct page *, unsigned, unsigned);
 205 int nobh_truncate_page(struct address_space *, loff_t);
 206 int nobh_writepage(struct page *page, get_block_t *get_block,
 207                         struct writeback_control *wbc);
 208
 209
 210 /*
 211  * inline definitions
 212  */
 213
 214 static inline void attach_page_buffers(struct page *page,
 215                 struct buffer_head *head)
 216 {
 217         page_cache_get(page);
 218         SetPagePrivate(page);
 219         page->private = (unsigned long)head;
 220 }
 221
 222 static inline void get_bh(struct buffer_head *bh)
 223 {
 224         atomic_inc(&bh->b_count);
 225 }
 226
 227 static inline void put_bh(struct buffer_head *bh)
 228 {
 229         smp_mb__before_atomic_dec();
 230         atomic_dec(&bh->b_count);
 231 }
 232
 233 static inline void brelse(struct buffer_head *bh)
 234 {
 235         if (bh)
 236                 __brelse(bh);
 237 }
 238
 239 static inline void bforget(struct buffer_head *bh)
 240 {
 241         if (bh)
 242                 __bforget(bh);
 243 }
 244
 245 static inline struct buffer_head *
 246 sb_bread(struct super_block *sb, sector_t block)
 247 {
 248         return __bread(sb->s_bdev, block, sb->s_blocksize);
 249 }
 250
 251 static inline void
 252 sb_breadahead(struct super_block *sb, sector_t block)
 253 {
 254         __breadahead(sb->s_bdev, block, sb->s_blocksize);
 255 }
 256
 257 static inline struct buffer_head *
 258 sb_getblk(struct super_block *sb, sector_t block)
 259 {
 260         return __getblk(sb->s_bdev, block, sb->s_blocksize);
 261 }
 262
 263 static inline struct buffer_head *
 264 sb_find_get_block(struct super_block *sb, sector_t block)
 265 {
 266         return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
 267 }
 268
 269 static inline void
 270 map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
 271 {
 272         set_buffer_mapped(bh);
 273         bh->b_bdev = sb->s_bdev;
 274         bh->b_blocknr = block;
 275 }
 276
 277 /*
 278  * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into
 279  * __wait_on_buffer() just to trip a debug check.  Because debug code in inline
 280  * functions is bloaty.
 281  */
 282 static inline void wait_on_buffer(struct buffer_head *bh)
 283 {
 284         might_sleep();
 285         if (buffer_locked(bh) || atomic_read(&bh->b_count) == 0)
 286                 __wait_on_buffer(bh);
 287 }
 288
 289 static inline void lock_buffer(struct buffer_head *bh)
 290 {
 291         might_sleep();
 292         if (test_set_buffer_locked(bh))
 293                 __lock_buffer(bh);
 294 }
 295
 296 #endif /* _LINUX_BUFFER_HEAD_H */