tree 0f81015c01834b97fdb5646a63c3fe1a24936d81
parent 56c819df77f96c3fc0c2a979e12b478403728790
author Tejun Heo <htejun@gmail.com> 1203417338 +0100
committer Jens Axboe <jens.axboe@oracle.com> 1203417338 +0100

block: update bio according to DMA alignment padding

DMA start address and transfer size alignment for PC requests are
achieved using bio_copy_user() instead of bio_map_user().  This works
because bio_copy_user() always uses full pages and block DMA alignment
isn't allowed to go over PAGE_SIZE.

However, the implementation didn't update the last bio of the request
to make this padding visible to lower layers.  This patch makes
blk_rq_map_user() extend the last bio such that it includes the
padding area and the size of area pointed to by the request is
properly aligned.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>