[SCSI] block: make blk_rq_map_user take a NULL user-space buffer for WRITE

The commit 818827669d85b84241696ffef2de485db46b0b5e (block: make
blk_rq_map_user take a NULL user-space buffer) extended
blk_rq_map_user to accept a NULL user-space buffer with a READ
command. It was necessary to convert sg to use the block layer mapping
API.

This patch extends blk_rq_map_user again for a WRITE command. It is
necessary to convert st and osst drivers to use the block layer
apping API.

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/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 7d0b3d9ee43b..8f0bd3f7a59f 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -1670,6 +1670,7 @@ static int sg_start_req(Sg_request *srp, unsigned char *cmd)
                 md->page_order = req_schp->page_order;
                 md->nr_entries = req_schp->k_use_sg;
                 md->offset = 0;
+                md->null_mapped = hp->dxferp ? 0 : 1;
         }
 
         if (iov_count)