Revert "Merge branch 'odirect'"

This reverts ccf01ef7 commit.

No idea how git managed this one: when I asked it to merge the odirect
topic branch it actually generated a patch which reverted the change.

Reverting the 'merge' will once again reveal Chuck's recent NFS/O_DIRECT
work to the world.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>