NAME
__bread - reads a specified block and returns the bh
SYNOPSIS
struct buffer_head * __bread (struct block_device * bdev,
sector_t block, int 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.