Introduce btrfs_iget helper

Date: Mon, 21 Jul 2008 02:01:04 +0530
This patch introduces a btrfs_iget helper to be used in NFS support.

Signed-off-by: Balaji Rao <balajirrao@gmail.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>