ovl: use O_LARGEFILE in ovl_copy_up()

ovl: use O_LARGEFILE in ovl_copy_up()

Orabug: 26619890

Open the lower file with O_LARGEFILE in ovl_copy_up().

Pass O_LARGEFILE unconditionally in ovl_copy_up_data() as it's purely for
catching 32-bit userspace dealing with a file large enough that it'll be
mishandled if the application isn't aware that there might be an integer
overflow.  Inside the kernel, there shouldn't be any problems.

Reported-by: Ulrich Obergfell <uobergfe@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Cc: <stable@vger.kernel.org> # v3.18+
(cherry picked from commit 0480334fa60488d12ae101a02d7d9e1a3d03d7dd)
Signed-off-by: Somasundaram Krishnasamy <somasundaram.krishnasamy@oracle.com>
Reviewed-by: Kirtikar Kashyap <kirtikar.kashyap@oracle.com>
Reviewed-by:  Ethan Zhao <ethan.zhao@oracle.com>