[RFC] weirdness in f2fs_rename() with RENAME_WHITEOUT

[Al Viro <viro@zeniv.linux.org.uk>]

[f2fs folks Cc'd]

	There's something very odd in f2fs_rename();
this:
        f2fs_down_write(&F2FS_I(old_inode)->i_sem);
        if (!old_dir_entry || whiteout)
                file_lost_pino(old_inode);
        else   
                /* adjust dir's i_pino to pass fsck check */
                f2fs_i_pino_write(old_inode, new_dir->i_ino);
        f2fs_up_write(&F2FS_I(old_inode)->i_sem);
and this:
                if (old_dir != new_dir && !whiteout)
                        f2fs_set_link(old_inode, old_dir_entry,
                                                old_dir_page, new_dir);
                else
                        f2fs_put_page(old_dir_page, 0);
The latter really stinks, especially considering
struct dentry *f2fs_get_parent(struct dentry *child)
{
        struct page *page;
        unsigned long ino = f2fs_inode_by_name(d_inode(child), &dotdot_name, &page);

        if (!ino) {
                if (IS_ERR(page))
                        return ERR_CAST(page);
                return ERR_PTR(-ENOENT);
        }
        return d_obtain_alias(f2fs_iget(child->d_sb, ino));
}

You want correct inumber in the ".." link.  And cross-directory
rename does move the source to new parent, even if you'd been asked
to leave a whiteout in the old place.

Why is that stuff conditional on whiteout?  AFAICS, that went into the
tree in the same commit that added RENAME_WHITEOUT support on f2fs,
mentioning "For now, we just try to follow the way that xfs/ext4 use"
in commit message.  But ext4 does *NOT* do anything of that sort -
at the time of that commit the relevant piece had been
        if (old.dir_bh) {
		retval = ext4_rename_dir_finish(handle, &old, new.dir->i_ino);
and old.dir_bh is set by
                retval = ext4_rename_dir_prepare(handle, &old);
a few lines prior, which is not conditional upon the whiteout.

What am I missing there?