to #30030885

commit 614c026e8a46636198da93ec30719f93975bb26a upstream

We want cached data to synced with the userspace filesystem on close(), for
example to allow getting correct st_blocks value.  Do this regardless of
whether the userspace filesystem implements a FLUSH method or not.
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NEryu Guan <eguan@linux.alibaba.com>
Reviewed-by: NLiu Bo <bo.liu@linux.alibaba.com>