[SCSI] block: fix the partial mappings with struct rq_map_data

This fixes bio_copy_user_iov to properly handle the partial mappings
with struct rq_map_data (which only sg uses for now but st and osst
will shortly). It adds the offset member to struct rq_map_data and
changes blk_rq_map_user to update it so that bio_copy_user_iov can add
an appropriate page frame via bio_add_pc_page().

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

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 7035cec583b6..811e5342c452 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -690,6 +690,7 @@ struct rq_map_data {
         struct page **pages;
         int page_order;
         int nr_entries;
+        unsigned long offset;
 };
 
 struct req_iterator {