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.
Itīs the callers responsibility to make sure this happens. The original
bio must be passed back in to blk_rq_unmap_user for proper unmapping.