LU-12026 mdt: MDS stores atime|mtime|ctime during close

LU-12026 mdt: MDS stores atime|mtime|ctime during close

In order to make direct inode scanning on the MDT useful, in
addition to storing the file size/blocks via LSOM on the MDT, we
also need to store the atime/mtime/ctime on the MDT inodes.

Currently the atime is already lazily updated on the MDS (at
close time). In this patch, the final mtime/ctime are sent to the
MDS at close time and updated on the MDT inode, and make MDT-only
scanning workable.

Signed-off-by: Qian Yingjin <qian@ddn.com>
Change-Id: I4465281a03d70919c388cb241c16eebcb03e850f
Reviewed-on: https://review.whamcloud.com/36286
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Li Xi <lixi@ddn.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>