blk_rq_map_sg doesn't initialize sg->dma_address/length to zero
anymore. Some low level drivers reuse sg lists without initializing so
IOMMUs might get non-zero dma_address/length. If map_sg fails, we need
pass the number of the mapped entries to gart_unmap_sg.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
map_sg could copy the last sg element to another position (if merging
some elements). It breaks sg chaining. This copies only
dma_address/length instead of the whole sg element.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
