Provided by:
linux-doc-2.6.15_2.6.15-23.39_all 
NAME
bio_copy_user - copy user data to bio
SYNOPSIS
struct bio * bio_copy_user (request_queue_t * q, unsigned long uaddr,
unsigned int len, int write_to_vm);
ARGUMENTS
q destination block queue
uaddr start of user address
len length in bytes
write_to_vm
bool indicating writing to pages or not
DESCRIPTION
Prepares and returns a bio for indirect user io, bouncing data to/from
kernel pages as necessary. Must be paired with call bio_uncopy_user on
io completion.