Use igrab_fs to hod refcounts on the inodes of orphans.

Use igrab_fs to hod refcounts on the inodes of orphans.

We currently hold a refcount on the inodes of dir orphans.
We need the filesystem (super_block) as well.

Also, while we don't really need a similar refcount for inode orphans,
it doesn't hurt.

So simplify the tracking of whether we need to take such a refcount,
use iget_fs to grab the super_block as well, and also take a ref in
lafs_add_orphans, which was missing.

Signed-off-by: NeilBrown <neilb@suse.de>