block: add and use scsi_blk_cmd_ioctl

Introduce a wrapper around scsi_cmd_ioctl that takes a block device.

The function will then be enhanced to detect partition block devices
and, in that case, subject the ioctls to whitelisting.

Cc: linux-scsi@vger.kernel.org
Cc: Jens Axboe <axboe@kernel.dk>
Cc: James Bottomley <JBottomley@parallels.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/block/ub.c b/drivers/block/ub.c
index 0e376d4..7333b9e 100644
--- a/drivers/block/ub.c
+++ b/drivers/block/ub.c
@@ -1744,12 +1744,11 @@
 static int ub_bd_ioctl(struct block_device *bdev, fmode_t mode,
     unsigned int cmd, unsigned long arg)
 {
-	struct gendisk *disk = bdev->bd_disk;
 	void __user *usermem = (void __user *) arg;
 	int ret;
 
 	mutex_lock(&ub_mutex);
-	ret = scsi_cmd_ioctl(disk->queue, disk, mode, cmd, usermem);
+	ret = scsi_cmd_blk_ioctl(bdev, mode, cmd, usermem);
 	mutex_unlock(&ub_mutex);
 
 	return ret;