[GFS2] gfs2 knows of directories which it chooses not to display

This is for Red Hat bugzilla bug bz #222302:

Moving a virtual IP from node to node between two NFS-over-GFS2
servers was causing one of the GFS2 servers to become confused and
reference a deleted inode.  The problem was due to vfs dentries that did
not reference the gfs2_dops and therefore didn't call the gfs2 revalidate
code to revalidate a dentry after a directory had been deleted & recreated.
This patch is a crosswrite from a RHEL4 bug found in GFS1 as
bz #190756 and it is against the latest -nmw git tree.

Signed-off-by: Robert Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>