Btrfs: fix filemap_flush call in btrfs_file_release

Btrfs: fix filemap_flush call in btrfs_file_release

commit f6dc45c7a93a011dff6eb9b2ffda59c390c7705a upstream.

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: Chris Mason <clm@fb.com>
Reported-by: Miao Xie <miaox@cn.fujitsu.com>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>