xfs: merge _xfs_log_force_lsn and xfs_log_force_lsn

Switch to a single interface for flushing the log to a specific LSN, which
gives consistent trace point coverage and a less confusing interface.

The was only a single user of the previous xfs_log_force_lsn function,
which now also passes a NULL log_flushed argument.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index 2ad08ec..d6d8f9d 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -970,7 +970,7 @@ __xfs_trans_commit(
 	 * log out now and wait for it.
 	 */
 	if (sync) {
-		error = _xfs_log_force_lsn(mp, commit_lsn, XFS_LOG_SYNC, NULL);
+		error = xfs_log_force_lsn(mp, commit_lsn, XFS_LOG_SYNC, NULL);
 		XFS_STATS_INC(mp, xs_trans_sync);
 	} else {
 		XFS_STATS_INC(mp, xs_trans_async);