xfs: flush data dev on external log write

mainline-inclusion
from mainline-v5.14-rc1
commit b1e27239
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4KIAO
CVE: NA

Reference:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b1e27239b9169f07edba0ca0e52805645a1768ba



-------------------------------------------------

We incorrectly flush the log device instead of the data device when
trying to ensure metadata is correctly on disk before writing the
unmount record.

Fixes: eef983ff ("xfs: journal IO cache flush reductions")
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Guo Xuenan <guoxuenan@huawei.com>
Reviewed-by: Lihong Kou <koulihong@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>