xfs: define a flags field for the AG geometry ioctl structure

Define a flags field for the AG geometry ioctl structure.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

fs/xfs/xfs_ioctl.c

@@ -1038,6 +1038,10 @@ xfs_ioc_ag_geometry(
 
 	if (copy_from_user(&ageo, arg, sizeof(ageo)))
 		return -EFAULT;
+	if (ageo.ag_flags)
+		return -EINVAL;
+	if (memchr_inv(&ageo.ag_reserved, 0, sizeof(ageo.ag_reserved)))
+		return -EINVAL;
 
 	error = xfs_ag_get_geometry(mp, ageo.ag_number, &ageo);
 	if (error)