struct bio

struct bio:

struct block_device  *bi_bdev;

struct bio_vec          *bi_io_vec;     /* the actual vec list */

unsigned short          bi_vcnt;        /* how many bio_vec's */

unsigned int            bi_size;        /* residual I/O count */

struct bio_vec:

  struct page     *bv_page;

  unsigned int    bv_len;

  unsigned int    bv_offset;