Man page 9 : bio_map_user

bio_map_user - map user address into bio

struct bio * bio_map_user(struct request_queue *  q , struct block_device *  bdev , unsigned long  uaddr , unsigned int  len , int  write_to_vm , gfp_t  gfp_mask );

q
    the struct request_queue for the bio

bdev
    destination block device

uaddr
    start of user address

len
    length in bytes

write_to_vm
    bool indicating writing to pages or not

gfp_mask
    memory allocation flags

Map the user space address into a bio suitable for io to a block device. Returns an error pointer in case of error.