exfat_find_empty_entry
ret = exfat_find_empty_entry(root_inode, &clu, 1, &es);
int exfat_find_empty_entry(struct inode *inode,
newentry = exfat_find_empty_entry(parent_inode, &dir,
newentry = exfat_find_empty_entry(parent_inode, &newdir,
dentry = exfat_find_empty_entry(inode, &info->dir, num_entries, &es);