Do not revalidate slave stripes while holding master lock.
Otherwise if the revalidating slaves are blocked, then the
master lock can not be released in time.

Remove some unnecesary merging in ll_revalidate_slave(), and
the attributes will be stored in each stripe, only
merging them if required.

Signed-off-by: wang di <di.wang@intel.com>
Change-Id: I57c43236894e2bbbf9a20b1d90c5ab2a5dc62ef1
Reviewed-on: http://review.whamcloud.com/13432


Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>