We should only be flushing on close if the file was flagged as needing
it during truncate.  I broke this with my ordered data vs transaction
commit deadlock fix.

Thanks to Miao Xie for catching this.
Signed-off-by: NChris Mason <clm@fb.com>
Reported-by: NMiao Xie <miaox@cn.fujitsu.com>
Reported-by: NFengguang Wu <fengguang.wu@intel.com>