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/wait.h>
  14 #include <asm/atomic.h>
  15
  16 enum bh_state_bits {
  17         BH_Uptodate,    /* Contains valid data */
  18         BH_Dirty,       /* Is dirty */
  19         BH_Lock,        /* Is locked */
  20         BH_Req,         /* Has been submitted for I/O */
  21
  22         BH_Mapped,      /* Has a disk mapping */
  23         BH_New,         /* Disk mapping was newly created by get_block */
  24         BH_Async_Read,  /* Is under end_buffer_async_read I/O */
  25         BH_Async_Write, /* Is under end_buffer_async_write I/O */
  26         BH_Delay,       /* Buffer is not yet allocated on disk */
  27         BH_Boundary,    /* Block is followed by a discontiguity */
  28         BH_Write_EIO,   /* I/O error on write */
  29         BH_Ordered,     /* ordered write */
  30         BH_Eopnotsupp,  /* operation not supported (barrier) */
  31
  32         BH_PrivateStart,/* not a state bit, but the first bit available
  33                          * for private allocation by other entities
  34                          */
  35 };
  36
  37 #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512)
  38
  39 struct page;
  40 struct buffer_head;
  41 struct address_space;
  42 typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
  43
  44 /*
  45  * Keep related fields in common cachelines.  The most commonly accessed
  46  * field (b_state) goes at the start so the compiler does not generate
  47  * indexed addressing for it.
  48  */
  49 struct buffer_head {
  50         /* First cache line: */
  51         unsigned long b_state;          /* buffer state bitmap (see above) */
  52         struct buffer_head *b_this_page;/* circular list of page's buffers */
  53         struct page *b_page;            /* the page this bh is mapped to */
  54         atomic_t b_count;               /* users using this block */
  55         u32 b_size;                     /* block size */
  56
  57         sector_t b_blocknr;             /* block number */
  58         char *b_data;                   /* pointer to data block */
  59
  60         struct block_device *b_bdev;
  61         bh_end_io_t *b_end_io;          /* I/O completion */
  62         void *b_private;                /* reserved for b_end_io */
  63         struct list_head b_assoc_buffers; /* associated with another mapping */
  64 };
  65
  66 /*
  67  * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
  68  * and buffer_foo() functions.
  69  */
  70 #define BUFFER_FNS(bit, name)                                           \
  71 static inline void set_buffer_##name(struct buffer_head *bh)            \
  72 {                                                                       \
  73         set_bit(BH_##bit, &(bh)->b_state);                              \
  74 }                                                                       \
  75 static inline void clear_buffer_##name(struct buffer_head *bh)          \
  76 {                                                                       \
  77         clear_bit(BH_##bit, &(bh)->b_state);                            \
  78 }                                                                       \
  79 static inline int buffer_##name(struct buffer_head *bh)                 \
  80 {                                                                       \
  81         return test_bit(BH_##bit, &(bh)->b_state);                      \
  82 }
  83
  84 /*
  85  * test_set_buffer_foo() and test_clear_buffer_foo()
  86  */
  87 #define TAS_BUFFER_FNS(bit, name)                                       \
  88 static inline int test_set_buffer_##name(struct buffer_head *bh)        \
  89 {                                                                       \
  90         return test_and_set_bit(BH_##bit, &(bh)->b_state);              \
  91 }                                                                       \
  92 static inline int test_clear_buffer_##name(struct buffer_head *bh)      \
  93 {                                                                       \
  94         return test_and_clear_bit(BH_##bit, &(bh)->b_state);            \
  95 }                                                                       \
  96
  97 /*
  98  * Emit the buffer bitops functions.   Note that there are also functions
  99  * of the form "mark_buffer_foo()".  These are higher-level functions which
 100  * do something in addition to setting a b_state bit.
 101  */
 102 BUFFER_FNS(Uptodate, uptodate)
 103 BUFFER_FNS(Dirty, dirty)
 104 TAS_BUFFER_FNS(Dirty, dirty)
 105 BUFFER_FNS(Lock, locked)
 106 TAS_BUFFER_FNS(Lock, locked)
 107 BUFFER_FNS(Req, req)
 108 TAS_BUFFER_FNS(Req, req)
 109 BUFFER_FNS(Mapped, mapped)
 110 BUFFER_FNS(New, new)
 111 BUFFER_FNS(Async_Read, async_read)
 112 BUFFER_FNS(Async_Write, async_write)
 113 BUFFER_FNS(Delay, delay)
 114 BUFFER_FNS(Boundary, boundary)
 115 BUFFER_FNS(Write_EIO, write_io_error)
 116 BUFFER_FNS(Ordered, ordered)
 117 BUFFER_FNS(Eopnotsupp, eopnotsupp)
 118
 119 #define bh_offset(bh)           ((unsigned long)(bh)->b_data & ~PAGE_MASK)
 120 #define touch_buffer(bh)        mark_page_accessed(bh->b_page)
 121
 122 /* If we *know* page->private refers to buffer_heads */
 123 #define page_buffers(page)                                      \
 124         ({                                                      \
 125                 BUG_ON(!PagePrivate(page));             \
 126                 ((struct buffer_head *)(page)->private);        \
 127         })
 128 #define page_has_buffers(page)  PagePrivate(page)
 129
 130 /*
 131  * Declarations
 132  */
 133
 134 void FASTCALL(mark_buffer_dirty(struct buffer_head *bh));
 135 void init_buffer(struct buffer_head *, bh_end_io_t *, void *);
 136 void set_bh_page(struct buffer_head *bh,
 137                 struct page *page, unsigned long offset);
 138 int try_to_free_buffers(struct page *);
 139 void create_empty_buffers(struct page *, unsigned long,
 140                         unsigned long b_state);
 141 void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
 142 void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
 143 void end_buffer_async_write(struct buffer_head *bh, int uptodate);
 144
 145 /* Things to do with buffers at mapping->private_list */
 146 void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
 147 int inode_has_buffers(struct inode *);
 148 void invalidate_inode_buffers(struct inode *);
 149 int remove_inode_buffers(struct inode *inode);
 150 int sync_mapping_buffers(struct address_space *mapping);
 151 void unmap_underlying_metadata(struct block_device *bdev, sector_t block);
 152
 153 void mark_buffer_async_write(struct buffer_head *bh);
 154 void invalidate_bdev(struct block_device *, int);
 155 int sync_blockdev(struct block_device *bdev);
 156 void __wait_on_buffer(struct buffer_head *);
 157 wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
 158 void wake_up_buffer(struct buffer_head *bh);
 159 int fsync_bdev(struct block_device *);
 160 struct super_block *freeze_bdev(struct block_device *);
 161 void thaw_bdev(struct block_device *, struct super_block *);
 162 int fsync_super(struct super_block *);
 163 int fsync_no_super(struct block_device *);
 164 struct buffer_head *__find_get_block(struct block_device *, sector_t, int);
 165 struct buffer_head * __getblk(struct block_device *, sector_t, int);
 166 void __brelse(struct buffer_head *);
 167 void __bforget(struct buffer_head *);
 168 void __breadahead(struct block_device *, sector_t block, int size);
 169 struct buffer_head *__bread(struct block_device *, sector_t block, int size);
 170 struct buffer_head *alloc_buffer_head(int gfp_flags);
 171 void free_buffer_head(struct buffer_head * bh);
 172 void FASTCALL(unlock_buffer(struct buffer_head *bh));
 173 void FASTCALL(__lock_buffer(struct buffer_head *bh));
 174 void ll_rw_block(int, int, struct buffer_head * bh[]);
 175 int sync_dirty_buffer(struct buffer_head *bh);
 176 int submit_bh(int, struct buffer_head *);
 177 void write_boundary_block(struct block_device *bdev,
 178                         sector_t bblock, unsigned blocksize);
 179
 180 extern int buffer_heads_over_limit;
 181
 182 /*
 183  * Generic address_space_operations implementations for buffer_head-backed
 184  * address_spaces.
 185  */
 186 int try_to_release_page(struct page * page, int gfp_mask);
 187 int block_invalidatepage(struct page *page, unsigned long offset);
 188 int block_write_full_page(struct page *page, get_block_t *get_block,
 189                                 struct writeback_control *wbc);
 190 int block_read_full_page(struct page*, get_block_t*);
 191 int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
 192 int cont_prepare_write(struct page*, unsigned, unsigned, get_block_t*,
 193                                 loff_t *);
 194 int generic_cont_expand(struct inode *inode, loff_t size) ;
 195 int block_commit_write(struct page *page, unsigned from, unsigned to);
 196 int block_sync_page(struct page *);
 197 sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
 198 int generic_commit_write(struct file *, struct page *, unsigned, unsigned);
 199 int block_truncate_page(struct address_space *, loff_t, get_block_t *);
 200 int file_fsync(struct file *, struct dentry *, int);
 201 int nobh_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
 202 int nobh_commit_write(struct file *, struct page *, unsigned, unsigned);
 203 int nobh_truncate_page(struct address_space *, loff_t);
 204
 205 /*
 206  * inline definitions
 207  */
 208
 209 static inline void get_bh(struct buffer_head *bh)
 210 {
 211         atomic_inc(&bh->b_count);
 212 }
 213
 214 static inline void put_bh(struct buffer_head *bh)
 215 {
 216         smp_mb__before_atomic_dec();
 217         atomic_dec(&bh->b_count);
 218 }
 219
 220 static inline void brelse(struct buffer_head *bh)
 221 {
 222         if (bh)
 223                 __brelse(bh);
 224 }
 225
 226 static inline void bforget(struct buffer_head *bh)
 227 {
 228         if (bh)
 229                 __bforget(bh);
 230 }
 231
 232 static inline struct buffer_head *
 233 sb_bread(struct super_block *sb, sector_t block)
 234 {
 235         return __bread(sb->s_bdev, block, sb->s_blocksize);
 236 }
 237
 238 static inline void
 239 sb_breadahead(struct super_block *sb, sector_t block)
 240 {
 241         __breadahead(sb->s_bdev, block, sb->s_blocksize);
 242 }
 243
 244 static inline struct buffer_head *
 245 sb_getblk(struct super_block *sb, sector_t block)
 246 {
 247         return __getblk(sb->s_bdev, block, sb->s_blocksize);
 248 }
 249
 250 static inline struct buffer_head *
 251 sb_find_get_block(struct super_block *sb, sector_t block)
 252 {
 253         return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
 254 }
 255
 256 static inline void
 257 map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
 258 {
 259         set_buffer_mapped(bh);
 260         bh->b_bdev = sb->s_bdev;
 261         bh->b_blocknr = block;
 262 }
 263
 264 /*
 265  * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into
 266  * __wait_on_buffer() just to trip a debug check.  Because debug code in inline
 267  * functions is bloaty.
 268  */
 269 static inline void wait_on_buffer(struct buffer_head *bh)
 270 {
 271         might_sleep();
 272         if (buffer_locked(bh) || atomic_read(&bh->b_count) == 0)
 273                 __wait_on_buffer(bh);
 274 }
 275
 276 static inline void lock_buffer(struct buffer_head *bh)
 277 {
 278         might_sleep();
 279         if (test_set_buffer_locked(bh))
 280                 __lock_buffer(bh);
 281 }
 282
 283 #endif /* _LINUX_BUFFER_HEAD_H */