Name
__bread — 
     reads a specified block and returns the bh
 
Synopsis
struct buffer_head * __bread ( | struct block_device * bdev,  | 
|   | sector_t block,  | 
|   | unsigned size); | 
 
Arguments
bdev
     the block_device to read from
    
block
     number of block
    
size
     size (in bytes) to read
    
Description
   Reads a specified block, and returns buffer head that contains it.
   It returns NULL if the block was unreadable.