ceph: just skip unrecognized info in ceph_reply_info_extra

ceph: just skip unrecognized info in ceph_reply_info_extra

commit 1d3f87233e26362fc3d4e59f0f31a71b570f90b9 upstream.

In the future, we're going to want to extend the ceph_reply_info_extra
for create replies. Currently though, the kernel code doesn't accept an
extra blob that is larger than the expected data.

Change the code to skip over any unrecognized fields at the end of the
extra blob, rather than returning -EIO.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>