blk_rq_map_kern — map kernel data to a request, for REQ_BLOCK_PC usage
int blk_rq_map_kern
(struct request_queue * q, struct request * rq, void * kbuf, unsigned int len, gfp_t gfp_mask);
request queue where request should be inserted
request to fill
the kernel buffer
length of user data
memory allocation flags
Data will be mapped directly if possible. Otherwise a bounce buffer is used.