otherwise client umount can get stuck if MDS is down
for a reason. recovery-small/110k simulates this.

Signed-off-by: Alex Zhuravlev <bzzz@whamcloud.com>
Change-Id: I40f6059d429b51a877deb532c1d0302dba0d5c85
Reviewed-on: https://review.whamcloud.com/36297


Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Mike Pershin <mpershin@whamcloud.com>