[PATCH] Fix root hole in pktcdvd

ioctl_by_bdev may only be used INSIDE the kernel.  If the "arg" argument
refers to memory that is accessed by put_user/get_user in the ioctl
function, the memory needs to be in the kernel address space (that's the
set_fs(KERNEL_DS) doing in the ioctl_by_bdev).  This works on i386 because
even with set_fs(KERNEL_DS) the user space memory is still accessible with
put_user/get_user.  That is not true for s390.  In short the ioctl
implementation of the pktcdvd device driver is horribly broken.
Signed-off-by: NPeter Osterlund <petero2@telia.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/block/pktcdvd.c

@@ -2406,7 +2406,7 @@ static int pkt_ioctl(struct inode *inode, struct file *file, unsigned int cmd, u
 	case CDROM_LAST_WRITTEN:
 	case CDROM_SEND_PACKET:
 	case SCSI_IOCTL_SEND_COMMAND:
-		return ioctl_by_bdev(pd->bdev, cmd, arg);
+		return blkdev_ioctl(pd->bdev->bd_inode, file, cmd, arg);
 
 	case CDROMEJECT:
 		/*
@@ -2414,7 +2414,7 @@ static int pkt_ioctl(struct inode *inode, struct file *file, unsigned int cmd, u
 		 * have to unlock it or else the eject command fails.
 		 */
 		pkt_lock_door(pd, 0);
-		return ioctl_by_bdev(pd->bdev, cmd, arg);
+		return blkdev_ioctl(pd->bdev->bd_inode, file, cmd, arg);
 
 	default:
 		printk("pktcdvd: Unknown ioctl for %s (%x)\n", pd->name, cmd);