staging: lustre: llite: clear LLIF_DATA_MODIFIED in atomic

This flag should be cleared atomically after the op_data flag
MDS_DATA_MODIFIED is packed. Otherwise, if there exists an
operation to dirty the file again, the state may be missed on
the MDT.

Stop using spin lock lli_lock to protect operations of changing
file flags; using bit operations instead.

Signed-off-by: Jinshan Xiong <jinshan.xiong@intel.com>
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-6377
Reviewed-on: http://review.whamcloud.com/14100


Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>