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
  30         BH_PrivateStart,/* not a state bit, but the first bit available
  31                          * for private allocation by other entities
  32                          */
  33 };
  34
  35 #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512)
  36
  37 struct page;
  38 struct buffer_head;
  39 struct address_space;
  40 typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
  41
  42 /*
  43  * Keep related fields in common cachelines.  The most commonly accessed
  44  * field (b_state) goes at the start so the compiler does not generate
  45  * indexed addressing for it.
  46  */
  47 struct buffer_head {
  48         /* First cache line: */
  49         unsigned long b_state;          /* buffer state bitmap (see above) */
  50         atomic_t b_count;               /* users using this block */
  51         struct buffer_head *b_this_page;/* circular list of page's buffers */
  52         struct page *b_page;            /* the page this bh is mapped to */
  53
  54         sector_t b_blocknr;             /* block number */
  55         u32 b_size;                     /* block size */
  56         char *b_data;                   /* pointer to data block */
  57
  58         struct block_device *b_bdev;
  59         bh_end_io_t *b_end_io;          /* I/O completion */
  60         void *b_private;                /* reserved for b_end_io */
  61         struct list_head b_assoc_buffers; /* associated with another mapping */
  62 };
  63
  64 /*
  65  * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
  66  * and buffer_foo() functions.
  67  */
  68 #define BUFFER_FNS(bit, name)                                           \
  69 static inline void set_buffer_##name(struct buffer_head *bh)            \
  70 {                                                                       \
  71         set_bit(BH_##bit, &(bh)->b_state);                              \
  72 }                                                                       \
  73 static inline void clear_buffer_##name(struct buffer_head *bh)          \
  74 {                                                                       \
  75         clear_bit(BH_##bit, &(bh)->b_state);                            \
  76 }                                                                       \
  77 static inline int buffer_##name(struct buffer_head *bh)                 \
  78 {                                                                       \
  79         return test_bit(BH_##bit, &(bh)->b_state);                      \
  80 }
  81
  82 /*
  83  * test_set_buffer_foo() and test_clear_buffer_foo()
  84  */
  85 #define TAS_BUFFER_FNS(bit, name)                                       \
  86 static inline int test_set_buffer_##name(struct buffer_head *bh)        \
  87 {                                                                       \
  88         return test_and_set_bit(BH_##bit, &(bh)->b_state);              \
  89 }                                                                       \
  90 static inline int test_clear_buffer_##name(struct buffer_head *bh)      \
  91 {                                                                       \
  92         return test_and_clear_bit(BH_##bit, &(bh)->b_state);            \
  93 }                                                                       \
  94
  95 /*
  96  * Emit the buffer bitops functions.   Note that there are also functions
  97  * of the form "mark_buffer_foo()".  These are higher-level functions which
  98  * do something in addition to setting a b_state bit.
  99  */
 100 BUFFER_FNS(Uptodate, uptodate)
 101 BUFFER_FNS(Dirty, dirty)
 102 TAS_BUFFER_FNS(Dirty, dirty)
 103 BUFFER_FNS(Lock, locked)
 104 TAS_BUFFER_FNS(Lock, locked)
 105 BUFFER_FNS(Req, req)
 106 TAS_BUFFER_FNS(Req, req)
 107 BUFFER_FNS(Mapped, mapped)
 108 BUFFER_FNS(New, new)
 109 BUFFER_FNS(Async_Read, async_read)
 110 BUFFER_FNS(Async_Write, async_write)
 111 BUFFER_FNS(Delay, delay)
 112 BUFFER_FNS(Boundary, boundary)
 113 BUFFER_FNS(Write_EIO,write_io_error)
 114
 115 #define bh_offset(bh)           ((unsigned long)(bh)->b_data & ~PAGE_MASK)
 116 #define touch_buffer(bh)        mark_page_accessed(bh->b_page)
 117
 118 /* If we *know* page->private refers to buffer_heads */
 119 #define page_buffers(page)                                      \
 120         ({                                                      \
 121                 BUG_ON(!PagePrivate(page));             \
 122                 ((struct buffer_head *)(page)->private);        \
 123         })
 124 #define page_has_buffers(page)  PagePrivate(page)
 125
 126 /*
 127  * Declarations
 128  */
 129
 130 void FASTCALL(mark_buffer_dirty(struct buffer_head *bh));
 131 void init_buffer(struct buffer_head *, bh_end_io_t *, void *);
 132 void set_bh_page(struct buffer_head *bh,
 133                 struct page *page, unsigned long offset);
 134 int try_to_free_buffers(struct page *);
 135 void create_empty_buffers(struct page *, unsigned long,
 136                         unsigned long b_state);
 137 void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
 138 void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
 139 void end_buffer_async_write(struct buffer_head *bh, int uptodate);
 140
 141 /* Things to do with buffers at mapping->private_list */
 142 void buffer_insert_list(spinlock_t *lock,
 143                         struct buffer_head *, struct list_head *);
 144 void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
 145 int inode_has_buffers(struct inode *);
 146 void invalidate_inode_buffers(struct inode *);
 147 int remove_inode_buffers(struct inode *inode);
 148 int fsync_buffers_list(spinlock_t *lock, struct list_head *);
 149 int sync_mapping_buffers(struct address_space *mapping);
 150 void unmap_underlying_metadata(struct block_device *bdev, sector_t block);
 151
 152 void mark_buffer_async_read(struct buffer_head *bh);
 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 ll_rw_block(int, int, struct buffer_head * bh[]);
 174 void sync_dirty_buffer(struct buffer_head *bh);
 175 void submit_bh(int, struct buffer_head *);
 176 void write_boundary_block(struct block_device *bdev,
 177                         sector_t bblock, unsigned blocksize);
 178
 179 extern int buffer_heads_over_limit;
 180
 181 /*
 182  * Generic address_space_operations implementations for buffer_head-backed
 183  * address_spaces.
 184  */
 185 int try_to_release_page(struct page * page, int gfp_mask);
 186 int block_invalidatepage(struct page *page, unsigned long offset);
 187 int block_write_full_page(struct page *page, get_block_t *get_block,
 188                                 struct writeback_control *wbc);
 189 int block_read_full_page(struct page*, get_block_t*);
 190 int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
 191 int cont_prepare_write(struct page*, unsigned, unsigned, get_block_t*,
 192                                 loff_t *);
 193 int generic_cont_expand(struct inode *inode, loff_t size) ;
 194 int block_commit_write(struct page *page, unsigned from, unsigned to);
 195 int block_sync_page(struct page *);
 196 sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
 197 int generic_commit_write(struct file *, struct page *, unsigned, unsigned);
 198 int block_truncate_page(struct address_space *, loff_t, get_block_t *);
 199 int file_fsync(struct file *, struct dentry *, int);
 200 int nobh_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
 201 int nobh_commit_write(struct file *, struct page *, unsigned, unsigned);
 202 int nobh_truncate_page(struct address_space *, loff_t);
 203
 204 #define OSYNC_METADATA  (1<<0)
 205 #define OSYNC_DATA      (1<<1)
 206 #define OSYNC_INODE     (1<<2)
 207 int generic_osync_inode(struct inode *, struct address_space *, int);
 208
 209
 210 /*
 211  * inline definitions
 212  */
 213
 214 static inline void get_bh(struct buffer_head *bh)
 215 {
 216         atomic_inc(&bh->b_count);
 217 }
 218
 219 static inline void put_bh(struct buffer_head *bh)
 220 {
 221         smp_mb__before_atomic_dec();
 222         atomic_dec(&bh->b_count);
 223 }
 224
 225 static inline void brelse(struct buffer_head *bh)
 226 {
 227         if (bh)
 228                 __brelse(bh);
 229 }
 230
 231 static inline void bforget(struct buffer_head *bh)
 232 {
 233         if (bh)
 234                 __bforget(bh);
 235 }
 236
 237 static inline struct buffer_head *
 238 sb_bread(struct super_block *sb, sector_t block)
 239 {
 240         return __bread(sb->s_bdev, block, sb->s_blocksize);
 241 }
 242
 243 static inline void
 244 sb_breadahead(struct super_block *sb, sector_t block)
 245 {
 246         __breadahead(sb->s_bdev, block, sb->s_blocksize);
 247 }
 248
 249 static inline struct buffer_head *
 250 sb_getblk(struct super_block *sb, sector_t block)
 251 {
 252         return __getblk(sb->s_bdev, block, sb->s_blocksize);
 253 }
 254
 255 static inline struct buffer_head *
 256 sb_find_get_block(struct super_block *sb, sector_t block)
 257 {
 258         return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
 259 }
 260
 261 static inline void
 262 map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
 263 {
 264         set_buffer_mapped(bh);
 265         bh->b_bdev = sb->s_bdev;
 266         bh->b_blocknr = block;
 267 }
 268
 269 /*
 270  * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into
 271  * __wait_on_buffer() just to trip a debug check.  Because debug code in inline
 272  * functions is bloaty.
 273  */
 274 static inline void wait_on_buffer(struct buffer_head *bh)
 275 {
 276         if (buffer_locked(bh) || atomic_read(&bh->b_count) == 0)
 277                 __wait_on_buffer(bh);
 278 }
 279
 280 static inline void lock_buffer(struct buffer_head *bh)
 281 {
 282         while (test_set_buffer_locked(bh))
 283                 __wait_on_buffer(bh);
 284 }
 285
 286 #endif /* _LINUX_BUFFER_HEAD_H */