blk_rq_map_user(9)
NAME
blk_rq_map_user - map user data to a request, for REQ_BLOCK_PC usage
SYNOPSIS
int blk_rq_map_user(struct request_queue * q, struct request * rq,
void __user * ubuf, unsigned long len);
ARGUMENTS
- q
- request queue where request should be inserted
- rq
- request structure to fill
- ubuf
- the user buffer
- len
- length of user data
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.