ceph: fix file offset wrapping at 4GB on 32-bit archs

Cast the value before shifting so that we don't run out of bits with a
32-bit unsigned long.  This fixes wrapping of high file offsets into the
low 4GB of a file on disk, and the subsequent data corruption for large
files.

Signed-off-by: Sage Weil <sage@newdream.net>

diff --cc fs/ceph/addr.c
Simple merge