xfs: factor out a new xfs_log_force_inode helper

xfs: factor out a new xfs_log_force_inode helper

commit fd7796afc3c18a0f441d02e0488afd166fc938dc upstream.

Create a new helper to force the log up to the last LSN touching an
inode.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandan.babu@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>