LU-10406 mdt: invalidate cache upon LDLM lock

LU-10406 mdt: invalidate cache upon LDLM lock

given new components (like LFSCK) can access storage w/o LDLM
locking, it's possible to find cache stale. so MDT should
invalidate local cache explicitly once LDLM lock is granted.

also, OSP should invdalite any state requested before invalidation
request as LDLM lock and request can be handled in different
order on the target and source MDTs. for example, get_attr was
sent first, the target MDT serviced it first, but the reply got
delayed for a reason. in the meantime LDLM lock was requested,
granted and received by the source MDT before reply for get_attr.
IOW, we get a state with old (potentially stale) state and LDLM
lock granted.

Change-Id: I7b96465d98960617c96a45accfb30dbfbd0e1576
Signed-off-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-on: https://review.whamcloud.com/31194
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Fan Yong <fan.yong@intel.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>