Unlike on some other architectures ino_t is an unsigned int on s390.
So add an explicit cast to avoid lots of compile warnings:
In file included from include/trace/ftrace.h:285,
from include/trace/define_trace.h:61,
from include/trace/events/ext4.h:711,
from fs/ext4/super.c:50:
include/trace/events/ext4.h: In function 'ftrace_raw_output_ext4_free_inode':
include/trace/events/ext4.h:12: warning: format '%lu' expects type 'long unsigned int', but argument 4 has type 'ino_t'