Provided by: linux-doc-2.6.15_2.6.15-23.39_all bug

NAME

       blk_rq_map_user_iov  -  map  user  data  to a request, for REQ_BLOCK_PC
       usage

SYNOPSIS

       int blk_rq_map_user_iov  (request_queue_t * q, struct request * rq,
                                  struct sg_iovec * iov, int iov_count);

ARGUMENTS

       q      request queue where request should be inserted

       rq     request to map data to

       iov    pointer to the iovec

       iov_count
              number of elements in the iovec

DESCRIPTION

       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.

NOTE

       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.