exfat_cluster_walk
ret = exfat_cluster_walk(sb, &clu, exfat_bytes_to_cluster(sbi, off),
if (exfat_cluster_walk(sb, &clu, 1, p_dir->flags))
exfat_cluster_walk(sb, (pclu), 1, ALLOC_FAT_CHAIN)
if (exfat_cluster_walk(sb, &clu, step, chain->flags))