sg: set dxferp to NULL for READ with the older SG interface
With the older SG interface, we don't know a user-space address to
trasfer data when executing a SCSI command. So we can't pass a
user-space address to blk_rq_map_user.
This patch fixes sg to pass a NULL user-space address to
blk_rq_map_user so that it just sets up a request and bios with page
frames propely without data transfer.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index ed69292..50c07bc 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -615,7 +615,10 @@
else
hp->dxfer_direction = (mxsize > 0) ? SG_DXFER_FROM_DEV : SG_DXFER_NONE;
hp->dxfer_len = mxsize;
- hp->dxferp = (char __user *)buf + cmd_size;
+ if (hp->dxfer_direction == SG_DXFER_TO_DEV)
+ hp->dxferp = (char __user *)buf + cmd_size;
+ else
+ hp->dxferp = NULL;
hp->sbp = NULL;
hp->timeout = old_hdr.reply_len; /* structure abuse ... */
hp->flags = input_size; /* structure abuse ... */