Provided by: linux-doc-2.6.15_2.6.15-23.39_all
blk_rq_map_user - map user data to a request, for REQ_BLOCK_PC usage
int blk_rq_map_user (request_queue_t * q, struct request * rq,
void __user * ubuf, unsigned int len);
q request queue where request should be inserted
rq request structure to fill
ubuf the user buffer
len length of user data
Data will be mapped directly for zero copy io, if possible. Otherwise a
kernel bounce buffer is used.
A matching blk_rq_unmap_user must be issued at the end of io, while
still in process context.
The mapped bio may need to be bounced through blk_queue_bounce before
being submitted to the device, as pages mapped may be out of reach.
It’s the callers responsibility to make sure this happens. The original
bio must be passed back in to blk_rq_unmap_user for proper unmapping.