tree 694d09728733e65d604bf3e1f13679db73fc1d9a
parent 839e96afba87117befd39cf4e43f156edc8047a7
author FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> 1220340019 +0900
committer Jens Axboe <jens.axboe@oracle.com> 1223535371 +0200

block: make blk_rq_map_user take a NULL user-space buffer

This patch changes blk_rq_map_user to accept a NULL user-space buffer
with a READ command if rq_map_data is not NULL. Thus a caller can pass
page frames to lk_rq_map_user to just set up a request and bios with
page frames propely. bio_uncopy_user (called via blk_rq_unmap_user)
doesn't copy data to user space with such request.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>