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   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         BH_Uptodate_Lock,/* Used by the first bh in a page, to serialise
  23                           * IO completion of other buffers in the page
  24                           */
  25
  26         BH_Mapped,      /* Has a disk mapping */
  27         BH_New,         /* Disk mapping was newly created by get_block */
  28         BH_Async_Read,  /* Is under end_buffer_async_read I/O */
  29         BH_Async_Write, /* Is under end_buffer_async_write I/O */
  30         BH_Delay,       /* Buffer is not yet allocated on disk */
  31         BH_Boundary,    /* Block is followed by a discontiguity */
  32         BH_Write_EIO,   /* I/O error on write */
  33         BH_Ordered,     /* ordered write */
  34         BH_Eopnotsupp,  /* operation not supported (barrier) */
  35
  36         BH_PrivateStart,/* not a state bit, but the first bit available
  37                          * for private allocation by other entities
  38                          */
  39 };
  40
  41 #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512)
  42
  43 struct page;
  44 struct buffer_head;
  45 struct address_space;
  46 typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
  47
  48 /*
  49  * Keep related fields in common cachelines.  The most commonly accessed
  50  * field (b_state) goes at the start so the compiler does not generate
  51  * indexed addressing for it.
  52  */
  53 struct buffer_head {
  54         /* First cache line: */
  55         unsigned long b_state;          /* buffer state bitmap (see above) */
  56         struct buffer_head *b_this_page;/* circular list of page's buffers */
  57         struct page *b_page;            /* the page this bh is mapped to */
  58         atomic_t b_count;               /* users using this block */
  59         u32 b_size;                     /* block size */
  60
  61         sector_t b_blocknr;             /* block number */
  62         char *b_data;                   /* pointer to data block */
  63
  64         struct block_device *b_bdev;
  65         bh_end_io_t *b_end_io;          /* I/O completion */
  66         void *b_private;                /* reserved for b_end_io */
  67         struct list_head b_assoc_buffers; /* associated with another mapping */
  68 };
  69
  70 /*
  71  * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
  72  * and buffer_foo() functions.
  73  */
  74 #define BUFFER_FNS(bit, name)                                           \
  75 static inline void set_buffer_##name(struct buffer_head *bh)            \
  76 {                                                                       \
  77         set_bit(BH_##bit, &(bh)->b_state);                              \
  78 }                                                                       \
  79 static inline void clear_buffer_##name(struct buffer_head *bh)          \
  80 {                                                                       \
  81         clear_bit(BH_##bit, &(bh)->b_state);                            \
  82 }                                                                       \
  83 static inline int buffer_##name(const struct buffer_head *bh)           \
  84 {                                                                       \
  85         return test_bit(BH_##bit, &(bh)->b_state);                      \
  86 }
  87
  88 /*
  89  * test_set_buffer_foo() and test_clear_buffer_foo()
  90  */
  91 #define TAS_BUFFER_FNS(bit, name)                                       \
  92 static inline int test_set_buffer_##name(struct buffer_head *bh)        \
  93 {                                                                       \
  94         return test_and_set_bit(BH_##bit, &(bh)->b_state);              \
  95 }                                                                       \
  96 static inline int test_clear_buffer_##name(struct buffer_head *bh)      \
  97 {                                                                       \
  98         return test_and_clear_bit(BH_##bit, &(bh)->b_state);            \
  99 }                                                                       \
 100
 101 /*
 102  * Emit the buffer bitops functions.   Note that there are also functions
 103  * of the form "mark_buffer_foo()".  These are higher-level functions which
 104  * do something in addition to setting a b_state bit.
 105  */
 106 BUFFER_FNS(Uptodate, uptodate)
 107 BUFFER_FNS(Dirty, dirty)
 108 TAS_BUFFER_FNS(Dirty, dirty)
 109 BUFFER_FNS(Lock, locked)
 110 TAS_BUFFER_FNS(Lock, locked)
 111 BUFFER_FNS(Req, req)
 112 TAS_BUFFER_FNS(Req, req)
 113 BUFFER_FNS(Mapped, mapped)
 114 BUFFER_FNS(New, new)
 115 BUFFER_FNS(Async_Read, async_read)
 116 BUFFER_FNS(Async_Write, async_write)
 117 BUFFER_FNS(Delay, delay)
 118 BUFFER_FNS(Boundary, boundary)
 119 BUFFER_FNS(Write_EIO, write_io_error)
 120 BUFFER_FNS(Ordered, ordered)
 121 BUFFER_FNS(Eopnotsupp, eopnotsupp)
 122
 123 #define bh_offset(bh)           ((unsigned long)(bh)->b_data & ~PAGE_MASK)
 124 #define touch_buffer(bh)        mark_page_accessed(bh->b_page)
 125
 126 /* If we *know* page->private refers to buffer_heads */
 127 #define page_buffers(page)                                      \
 128         ({                                                      \
 129                 BUG_ON(!PagePrivate(page));             \
 130                 ((struct buffer_head *)(page)->private);        \
 131         })
 132 #define page_has_buffers(page)  PagePrivate(page)
 133
 134 /*
 135  * Declarations
 136  */
 137
 138 void FASTCALL(mark_buffer_dirty(struct buffer_head *bh));
 139 void init_buffer(struct buffer_head *, bh_end_io_t *, void *);
 140 void set_bh_page(struct buffer_head *bh,
 141                 struct page *page, unsigned long offset);
 142 int try_to_free_buffers(struct page *);
 143 struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
 144                 int retry);
 145 void create_empty_buffers(struct page *, unsigned long,
 146                         unsigned long b_state);
 147 void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
 148 void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
 149 void end_buffer_async_write(struct buffer_head *bh, int uptodate);
 150
 151 /* Things to do with buffers at mapping->private_list */
 152 void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
 153 int inode_has_buffers(struct inode *);
 154 void invalidate_inode_buffers(struct inode *);
 155 int remove_inode_buffers(struct inode *inode);
 156 int sync_mapping_buffers(struct address_space *mapping);
 157 void unmap_underlying_metadata(struct block_device *bdev, sector_t block);
 158
 159 void mark_buffer_async_write(struct buffer_head *bh);
 160 void invalidate_bdev(struct block_device *, int);
 161 int sync_blockdev(struct block_device *bdev);
 162 void __wait_on_buffer(struct buffer_head *);
 163 wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
 164 int fsync_bdev(struct block_device *);
 165 struct super_block *freeze_bdev(struct block_device *);
 166 void thaw_bdev(struct block_device *, struct super_block *);
 167 int fsync_super(struct super_block *);
 168 int fsync_no_super(struct block_device *);
 169 struct buffer_head *__find_get_block(struct block_device *, sector_t, int);
 170 struct buffer_head * __getblk(struct block_device *, sector_t, int);
 171 void __brelse(struct buffer_head *);
 172 void __bforget(struct buffer_head *);
 173 void __breadahead(struct block_device *, sector_t block, int size);
 174 struct buffer_head *__bread(struct block_device *, sector_t block, int size);
 175 struct buffer_head *alloc_buffer_head(unsigned int __nocast gfp_flags);
 176 void free_buffer_head(struct buffer_head * bh);
 177 void FASTCALL(unlock_buffer(struct buffer_head *bh));
 178 void FASTCALL(__lock_buffer(struct buffer_head *bh));
 179 void ll_rw_block(int, int, struct buffer_head * bh[]);
 180 int sync_dirty_buffer(struct buffer_head *bh);
 181 int submit_bh(int, struct buffer_head *);
 182 void write_boundary_block(struct block_device *bdev,
 183                         sector_t bblock, unsigned blocksize);
 184
 185 extern int buffer_heads_over_limit;
 186
 187 /*
 188  * Generic address_space_operations implementations for buffer_head-backed
 189  * address_spaces.
 190  */
 191 int try_to_release_page(struct page * page, int gfp_mask);
 192 int block_invalidatepage(struct page *page, unsigned long offset);
 193 int block_write_full_page(struct page *page, get_block_t *get_block,
 194                                 struct writeback_control *wbc);
 195 int block_read_full_page(struct page*, get_block_t*);
 196 int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
 197 int cont_prepare_write(struct page*, unsigned, unsigned, get_block_t*,
 198                                 loff_t *);
 199 int generic_cont_expand(struct inode *inode, loff_t size) ;
 200 int block_commit_write(struct page *page, unsigned from, unsigned to);
 201 int block_sync_page(struct page *);
 202 sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
 203 int generic_commit_write(struct file *, struct page *, unsigned, unsigned);
 204 int block_truncate_page(struct address_space *, loff_t, get_block_t *);
 205 int file_fsync(struct file *, struct dentry *, int);
 206 int nobh_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
 207 int nobh_commit_write(struct file *, struct page *, unsigned, unsigned);
 208 int nobh_truncate_page(struct address_space *, loff_t);
 209 int nobh_writepage(struct page *page, get_block_t *get_block,
 210                         struct writeback_control *wbc);
 211
 212
 213 /*
 214  * inline definitions
 215  */
 216
 217 static inline void attach_page_buffers(struct page *page,
 218                 struct buffer_head *head)
 219 {
 220         page_cache_get(page);
 221         SetPagePrivate(page);
 222         page->private = (unsigned long)head;
 223 }
 224
 225 static inline void get_bh(struct buffer_head *bh)
 226 {
 227         atomic_inc(&bh->b_count);
 228 }
 229
 230 static inline void put_bh(struct buffer_head *bh)
 231 {
 232         smp_mb__before_atomic_dec();
 233         atomic_dec(&bh->b_count);
 234 }
 235
 236 static inline void brelse(struct buffer_head *bh)
 237 {
 238         if (bh)
 239                 __brelse(bh);
 240 }
 241
 242 static inline void bforget(struct buffer_head *bh)
 243 {
 244         if (bh)
 245                 __bforget(bh);
 246 }
 247
 248 static inline struct buffer_head *
 249 sb_bread(struct super_block *sb, sector_t block)
 250 {
 251         return __bread(sb->s_bdev, block, sb->s_blocksize);
 252 }
 253
 254 static inline void
 255 sb_breadahead(struct super_block *sb, sector_t block)
 256 {
 257         __breadahead(sb->s_bdev, block, sb->s_blocksize);
 258 }
 259
 260 static inline struct buffer_head *
 261 sb_getblk(struct super_block *sb, sector_t block)
 262 {
 263         return __getblk(sb->s_bdev, block, sb->s_blocksize);
 264 }
 265
 266 static inline struct buffer_head *
 267 sb_find_get_block(struct super_block *sb, sector_t block)
 268 {
 269         return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
 270 }
 271
 272 static inline void
 273 map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
 274 {
 275         set_buffer_mapped(bh);
 276         bh->b_bdev = sb->s_bdev;
 277         bh->b_blocknr = block;
 278 }
 279
 280 /*
 281  * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into
 282  * __wait_on_buffer() just to trip a debug check.  Because debug code in inline
 283  * functions is bloaty.
 284  */
 285 static inline void wait_on_buffer(struct buffer_head *bh)
 286 {
 287         might_sleep();
 288         if (buffer_locked(bh) || atomic_read(&bh->b_count) == 0)
 289                 __wait_on_buffer(bh);
 290 }
 291
 292 static inline void lock_buffer(struct buffer_head *bh)
 293 {
 294         might_sleep();
 295         if (test_set_buffer_locked(bh))
 296                 __lock_buffer(bh);
 297 }
 298
 299 #endif /* _LINUX_BUFFER_HEAD_H */