My static checker marks everything from ntohl() as untrusted and it
complains we could have an underflow problem doing:

	return (u32 *)&ary->wc_array[nchunks];

Also on 32 bit systems the upper bound check could overflow.

Cc: stable@vger.kernel.org
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>