staging: lustre: create striped directory

1. client send create request to the master MDT, which
  will allocate FIDs and create slaves. for all of slaves.

2. Client needs to revalidate slaves during intent getattr
   and open request.

3. lmv_stripe_md will include attributes(size, nlink etc)
   from all of stripe, which will be protected by UPDATE lock.
   client needs to merge these attributes when update inode.

4. send create request to the MDT where the file is located,
   which can help creating master stripe of striped directory.

Signed-off-by: wang di <di.wang@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3529
Reviewed-on: http://review.whamcloud.com/7196


Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>