gcc gets a bit confused by the logic in ovl_setup_trap() and
can't figure out whether the local 'trap' variable in the caller
was initialized or not:
fs/overlayfs/super.c: In function 'ovl_fill_super':
fs/overlayfs/super.c:1333:4: error: 'trap' may be used uninitialized in this function [-Werror=maybe-uninitialized]
iput(trap);
^~~~~~~~~~
fs/overlayfs/super.c:1312:17: note: 'trap' was declared here
Reword slightly to make it easier for the compiler to understand.