Provided by: linux-doc-2.6.15_2.6.15-23.39_all
blk_rq_map_user_iov - map user data to a request, for REQ_BLOCK_PC
int blk_rq_map_user_iov (request_queue_t * q, struct request * rq,
struct sg_iovec * iov, int iov_count);
q request queue where request should be inserted
rq request to map data to
iov pointer to the iovec
number of elements in the iovec
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.