UBUNTU: SAUCE: NFSv4: Ensure that we check lock exclusive/shared type against open...

UBUNTU: SAUCE: NFSv4: Ensure that we check lock exclusive/shared type against open modes

BugLink: http://bugs.launchpad.net/bugs/974664

Since we may be simulating flock() locks using NFS byte range locks,
we can't rely on the VFS having checked the file open mode for us.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@vger.kernel.org
(cherry picked from commit 5de4815015e550bdd33f39650554325540356f0c git://git.linux-nfs.org/projects/trondmy/linux-nfs.git)

Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Signed-off-by: Leann Ogasawara <leann.ogasawara@canonical.com>