Man page 9 : bio_copy_kern

bio_copy_kern - copy kernel address into bio

struct bio * bio_copy_kern(struct request_queue *  q , void *  data , unsigned int  len , gfp_t  gfp_mask , int  reading );

q
    the struct request_queue for the bio

data
    pointer to buffer to copy

len
    length in bytes

gfp_mask
    allocation flags for bio and page allocation

reading
    data direction is READ

copy the kernel address into a bio suitable for io to a block device. Returns an error pointer in case of error.