LU-11020 osd: use right sync

LU-11020 osd: use right sync

use a sync_fs instead of journal flush only.
ext4 commit with similar change

commit 06a407f13daf9e48f0ef7189c7e54082b53940c7
Author: Dmitry Monakhov <dmonakhov@openvz.org>
Date:   Wed Jun 12 22:25:07 2013 -0400

ext4: fix data integrity for ext4_sync_fs

Inode's data or non journaled quota may be written w/o jounral so we
 _must_ send a barrier at the end of ext4_sync_fs. But it can be
skipped if journal commit will do it for us.

Cray-bug-id: LUS-5993
Signed-off-by: Alexey Lyashkov <c17817@cray.com>
Change-Id: Ie242b48d0b8ad61cf4d38ac0fb173176193716d9
Reviewed-on: https://review.whamcloud.com/32866
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Wang Shilong <wshilong@ddn.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>