/*
 * Draft of a genfs-based ext2fs_rename.  Not tested, not even compiled.
 *
 * -- Riastradh, 2011-12-13
 */

static const struct genfs_rename_ops ext2fs_genfs_rename_ops;

/*
 * ext2fs_rename: The hairiest vop, with the insanest API.
 *
 * Arguments:
 *
 * . fdvp (from directory vnode),
 * . fvp (from vnode),
 * . fcnp (from component name),
 * . tdvp (to directory vnode),
 * . tvp (to vnode, or NULL), and
 * . tcnp (to component name).
 *
 * Any pair of vnode parameters may have the same vnode.
 *
 * On entry,
 *
 * . fdvp, fvp, tdvp, and tvp are referenced,
 * . fdvp and fvp are unlocked, and
 * . tdvp and tvp (if nonnull) are locked.
 *
 * On exit,
 *
 * . fdvp, fvp, tdvp, and tvp (if nonnull) are unreferenced, and
 * . tdvp and tvp are unlocked.
 */
int
ext2fs_rename(void *v)
{
	struct vop_rename_args  /* {
		struct vnode *a_fdvp;
		struct vnode *a_fvp;
		struct componentname *a_fcnp;
		struct vnode *a_tdvp;
		struct vnode *a_tvp;
		struct componentname *a_tcnp;
	} */ *ap = v;
	struct vnode *fdvp = ap->a_fdvp;
	struct vnode *fvp = ap->a_fvp;
	struct componentname *fcnp = ap->a_fcnp;
	struct vnode *tdvp = ap->a_tdvp;
	struct vnode *tvp = ap->a_tvp;
	struct componentname *tcnp = ap->a_tcnp;
	kauth_cred_t cred;
	int error;

	KASSERT(fdvp != NULL);
	KASSERT(fvp != NULL);
	KASSERT(fcnp != NULL);
	KASSERT(fcnp->cn_nameptr != NULL);
	KASSERT(tdvp != NULL);
	KASSERT(tcnp != NULL);
	KASSERT(fcnp->cn_nameptr != NULL);
	/* KASSERT(VOP_ISLOCKED(fdvp) != LK_EXCLUSIVE); */
	/* KASSERT(VOP_ISLOCKED(fvp) != LK_EXCLUSIVE); */
	KASSERT(VOP_ISLOCKED(tdvp) == LK_EXCLUSIVE);
	KASSERT((tvp == NULL) || (VOP_ISLOCKED(tvp) == LK_EXCLUSIVE));
	KASSERT(fdvp->v_type == VDIR);
	KASSERT(tdvp->v_type == VDIR);

	cred = fcnp->cn_cred;
	KASSERT(tcnp->cn_cred == cred);

	/*
	 * Sanitize our world from the VFS insanity.  Unlock the target
	 * directory and node, which are locked.  Release the children,
	 * which are referenced.  Check for rename("x", "y/."), which
	 * it is our responsibility to reject, not the caller's.  (But
	 * the caller does reject rename("x/.", "y").  Go figure.)
	 */

	VOP_UNLOCK(tdvp);
	if ((tvp != NULL) && (tvp != tdvp))
		VOP_UNLOCK(tvp);

	vrele(fvp);
	if (tvp != NULL)
		vrele(tvp);

	if (tvp == tdvp) {
		error = EINVAL;
		goto out;
	}

	error = ext2fs_sane_rename(fdvp, fcnp, tdvp, tcnp, cred, false);

out:	/*
	 * All done, whether with success or failure.  Release the
	 * directory nodes now, as the caller expects from the VFS
	 * protocol.
	 */
	vrele(fdvp);
	vrele(tdvp);

	return error;
}

/*
 * ext2fs_sane_rename: The hairiest vop, with the saner API.
 *
 * Arguments:
 *
 * . fdvp (from directory vnode),
 * . fcnp (from component name),
 * . tdvp (to directory vnode), and
 * . tcnp (to component name).
 *
 * fdvp and tdvp must be referenced and unlocked.
 */
static int
ext2fs_sane_rename(
    struct vnode *fdvp, struct componentname *fcnp,
    struct vnode *tdvp, struct componentname *tcnp,
    kauth_cred_t cred, bool posixly_correct)
{
	struct ufs_lookup_results fulr, tulr;

	return genfs_sane_rename(&ext2fs_genfs_rename_ops,
	    fdvp, fcnp, &fulr, tdvp, tcnp, &tulr,
	    cred, posixly_correct);
}

/*
 * ext2fs_gro_de_equal_p: Return true if a_de and b_de represent the
 * same directory entries in a common directory.
 */
static int
ext2fs_gro_de_equal_p(struct mount *mp, void *a_de, void *b_de)
{
	struct ufs_lookup_results *a_ulr = a_de;
	struct ufs_lookup_results *b_ulr = b_de;

	(void)mp;
	KASSERT(mp != NULL);
	KASSERT(a_ulr != NULL);
	KASSERT(b_ulr != NULL);

	return (a_ulr->ulr_offset == b_ulr->ulr_offset);
}

/*
 * ext2fs_gro_directory_empty_p: Return true if the directory vp is
 * empty.  dvp is its parent.
 *
 * vp and dvp must be locked and referenced.
 */
static int
ext2fs_gro_directory_empty_p(struct mount *mp, kauth_cred_t cred,
    struct vnode *vp, struct vnode *dvp)
{

	(void)mp;
	KASSERT(mp != NULL);
	KASSERT(vp != NULL);
	KASSERT(dvp != NULL);
	KASSERT(vp != dvp);
	KASSERT(vp->v_mount == mp);
	KASSERT(dvp->v_mount == mp);
	KASSERT(VOP_ISLOCKED(vp) == LK_EXCLUSIVE);
	KASSERT(VOP_ISLOCKED(dvp) == LK_EXCLUSIVE);

	return ext2fs_dirempty(VTOI(vp), VTOI(dvp)->i_number, cred);
}

/*
 * ext2fs_gro_rename_check_possible: Check whether renaming fvp in fdvp
 * to tvp in tdvp is possible independent of credentials.
 */
static int
ext2fs_gro_rename_check_possible(struct mount *mp,
    struct vnode *fdvp, struct vnode *fvp,
    struct vnode *tdvp, struct vnode *tvp)
{

	KASSERT(mp != NULL);
	KASSERT(fdvp != NULL);
	KASSERT(fvp != NULL);
	KASSERT(tdvp != NULL);
	KASSERT(fdvp != fvp);
	KASSERT(fdvp != tvp);
	KASSERT(tdvp != fvp);
	KASSERT(tdvp != tvp);
	KASSERT(fvp != tvp);
	KASSERT(fdvp->v_mount == mp);
	KASSERT(fvp->v_mount == mp);
	KASSERT(tdvp->v_mount == mp);
	KASSERT((tvp == NULL) || (tvp->v_mount == mp));
	KASSERT(VOP_ISLOCKED(fdvp) == LK_EXCLUSIVE);
	KASSERT(VOP_ISLOCKED(fvp) == LK_EXCLUSIVE);
	KASSERT(VOP_ISLOCKED(tdvp) == LK_EXCLUSIVE);
	KASSERT((tvp == NULL) || (VOP_ISLOCKED(tvp) == LK_EXCLUSIVE));

	return genfs_ufslike_rename_check_possible(mp,
	    VTOI(fdvp)->i_e2fs_flags, VTOI(fvp)->i_e2fs_flags,
	    VTOI(tdvp)->i_e2fs_flags, VTOI(tvp)->i_e2fs_flags,
	    EXT2_IMMUTABLE, EXT2_APPEND);
}

/*
 * ext2fs_gro_rename_check_permitted: ...
 */
static int
ext2fs_gro_rename_check_permitted(struct mount *mp, kauth_cred_t cred,
    struct vnode *fdvp, struct vnode *fvp,
    struct vnode *tdvp, struct vnode *tvp)
{

	KASSERT(mp != NULL);
	KASSERT(fdvp != NULL);
	KASSERT(fvp != NULL);
	KASSERT(tdvp != NULL);
	KASSERT(fdvp != fvp);
	KASSERT(fdvp != tvp);
	KASSERT(tdvp != fvp);
	KASSERT(tdvp != tvp);
	KASSERT(fvp != tvp);
	KASSERT(fdvp->v_mount == mp);
	KASSERT(fvp->v_mount == mp);
	KASSERT(tdvp->v_mount == mp);
	KASSERT((tvp == NULL) || (tvp->v_mount == mp));
	KASSERT(VOP_ISLOCKED(fdvp) == LK_EXCLUSIVE);
	KASSERT(VOP_ISLOCKED(fvp) == LK_EXCLUSIVE);
	KASSERT(VOP_ISLOCKED(tdvp) == LK_EXCLUSIVE);
	KASSERT((tvp == NULL) || (VOP_ISLOCKED(tvp) == LK_EXCLUSIVE));

	return genfs_ufslike_rename_check_permitted(mp, cred,
	    fdvp, VTOI(fdvp)->i_e2fs_mode, VTOI(fdvp)->i_uid,
	    fvp, VTOI(fvp)->i_uid,
	    tdvp, VTOI(tdvp)->i_e2fs_mode, VTOI(tdvp)->i_uid,
	    tvp, (tvp? VTOI(tvp)->i_uid : 0));
}

/*
 * ext2fs_gro_remove_check_possible: ...
 */
static int
ext2fs_gro_remove_check_possible(struct mount *mp,
    struct vnode *dvp, struct vnode *vp)
{

	KASSERT(mp != NULL);
	KASSERT(dvp != NULL);
	KASSERT(vp != NULL);
	KASSERT(dvp != vp);
	KASSERT(dvp->v_mount == mp);
	KASSERT(vp->v_mount == mp);
	KASSERT(VOP_ISLOCKED(dvp) == LK_EXCLUSIVE);
	KASSERT(VOP_ISLOCKED(vp) == LK_EXCLUSIVE);

	return genfs_ufslike_remove_check_possible(mp,
	    VTOI(fdvp)->i_e2fs_flags, VTOI(fvp)->i_e2fs_flags,
	    EXT2_IMMUTABLE, EXT2_APPEND);
}

/*
 * ext2fs_gro_remove_check_permitted: ...
 */
static int
ext2fs_gro_remove_check_permitted(struct mount *mp, kauth_cred_t cred,
    struct vnode *dvp, struct vnode *vp)
{

	KASSERT(mp != NULL);
	KASSERT(dvp != NULL);
	KASSERT(vp != NULL);
	KASSERT(dvp != vp);
	KASSERT(dvp->v_mount == mp);
	KASSERT(vp->v_mount == mp);
	KASSERT(VOP_ISLOCKED(dvp) == LK_EXCLUSIVE);
	KASSERT(VOP_ISLOCKED(vp) == LK_EXCLUSIVE);

	return genfs_ufslike_remove_check_permitted(mp, cred,
	    dvp, VTOI(dvp)->i_e2fs_mode, VTOI(dvp)->i_uid, vp, VTOI(vp)->i_uid);
}

/*
 * ext2fs_gro_rename: Actually perform the rename operation.
 */
static int
ext2fs_gro_rename(struct mount *mp, kauth_cred_t cred,
    struct vnode *fdvp, struct componentname *fcnp,
    void *fde, struct vnode *fvp,
    struct vnode *tdvp, struct componentname *tcnp,
    void *tde, struct vnode *tvp)
{
	struct ufs_lookup_results *fulr = fde;
	struct ufs_lookup_results *tulr = tde;
	bool directory_p, reparent_p;

	KASSERT(mp != NULL);
	KASSERT(fdvp != NULL);
	KASSERT(fcnp != NULL);
	KASSERT(fulr != NULL);
	KASSERT(fvp != NULL);
	KASSERT(tdvp != NULL);
	KASSERT(tcnp != NULL);
	KASSERT(tulr != NULL);
	KASSERT(fdvp != fvp);
	KASSERT(fdvp != tvp);
	KASSERT(tdvp != fvp);
	KASSERT(tdvp != tvp);
	KASSERT(fvp != tvp);
	KASSERT(fdvp->v_mount == mp);
	KASSERT(fvp->v_mount == mp);
	KASSERT(tdvp->v_mount == mp);
	KASSERT((tvp == NULL) || (tvp->v_mount == mp));
	KASSERT(VOP_ISLOCKED(fdvp) == LK_EXCLUSIVE);
	KASSERT(VOP_ISLOCKED(fvp) == LK_EXCLUSIVE);
	KASSERT(VOP_ISLOCKED(tdvp) == LK_EXCLUSIVE);
	KASSERT((tvp == NULL) || (VOP_ISLOCKED(tvp) == LK_EXCLUSIVE));

	/*
	 * We will need to temporarily bump the link count, so make
	 * sure there is room to do so.
	 */
	if ((nlink_t)VTOI(fvp)->i_e2fs_nlink >= LINK_MAX)
		return EMLINK;

	/*
	 * XXX There is a pile of logic here to handle a voodoo flag
	 * IN_RENAME.  I think this is a vestige of days when the file
	 * system hackers didn't understand concurrency or race
	 * conditions; I believe it serves no useful function
	 * whatsoever.
	 */

	directory_p = (fvp->v_type == VDIR);
	KASSERT(directory_p == ((VTOI(fvp)->i_e2fs_mode & IFMT) == IFDIR));
	KASSERT((tvp == NULL) || (directory_p == (tvp->v_type == VDIR)));
	KASSERT((tvp == NULL) || (directory_p ==
		((VTOI(fvp)->i_e2fs_mode & IFMT) == IFDIR)));
	if (directory_p) {
		if (VTOI(fvp)->i_flag & IN_RENAME)
			return EINVAL;
		VTOI(fvp)->i_flag |= IN_RENAME;
	}

	reparent_p = (fdvp != tdvp);
	KASSERT(reparent_p == (VTOI(fdvp)->i_number != VTOI(tdvp)->i_number));

	/*
	 * 1) Bump link count while we're moving stuff
	 *    around.  If we crash somewhere before
	 *    completing our work, the link count
	 *    may be wrong, but correctable.
	 */

	KASSERT((nlink_t)VTOI(fvp)->i_e2fs_nlink < LINK_MAX);
	VTOI(fvp)->i_e2fs_nlink++;
	VTOI(fvp)->i_flag |= IN_CHANGE;
	error = ext2fs_update(fvp, NULL, NULL, UPDATE_WAIT);
	if (error)
		goto whymustithurtsomuch;

	/*
	 * 2) If target doesn't exist, link the target
	 *    to the source and unlink the source.
	 *    Otherwise, rewrite the target directory
	 *    entry to reference the source inode and
	 *    expunge the original entry's existence.
	 */

	if (tvp == NULL) {
		/*
		 * XXX WTF?  Why check here and not earlier?  Is this
		 * covered by checking v_mount earlier?
		 */
		KASSERT(VTOI(tdvp)->i_dev == VTOI(fvp)->i_dev);

		/*
		 * Account for ".." in new directory.
		 * When source and destination have the same
		 * parent we don't fool with the link count.
		 */
		if (directory_p && reparent_p) {
			if ((nlink_t)VTOI(tdvp)->i_e2fs_nlink >= LINK_MAX) {
				error = EMLINK;
				goto whymustithurtsomuch;
			}
			KASSERT((nlink_t)VTOI(tdvp)->i_e2fs_nlink < LINK_MAX);
			VTOI(tdvp)->i_e2fs_nlink++;
			VTOI(tdvp)->i_flag |= IN_CHANGE;
			error = ext2fs_update(tdvp, NULL, NULL, UPDATE_WAIT);
			if (error) {
				KASSERT(0 < VTOI(tdvp)->i_e2fs_nlink);
				VTOI(tdvp)->i_e2fs_nlink--;
				VTOI(tdvp)->i_flag |= IN_CHANGE;
				goto whymustithurtsomuch;
			}
		}

		error = ext2fs_direnter(VTOI(fvp), tdvp, tulr, tcnp);
		if (error) {
			if (directory_p && reparent_p) {
				KASSERT(0 < VTOI(tdvp)->i_e2fs_nlink);
				VTOI(tdvp)->i_e2fs_nlink--;
				VTOI(tdvp)->i_flag |= IN_CHANGE;
				(void)ext2fs_update(tdvp, NULL, NULL,
				    UPDATE_WAIT);
			}
			goto whymustithurtsomuch;
		}
	} else {
		/* XXX WTF?  Why check here and not earlier?  Is this
		 * covered by checking v_mount earlier?  */
		KASSERT(VTOI(tvp)->i_dev == VTOI(tdvp)->i_dev);
		KASSERT(VTOI(fvp)->i_dev == VTOI(fdvp)->i_dev);
		KASSERT(VTOI(tvp)->i_dev == VTOI(fvp)->i_dev);

		if (directory_p)
			/* XXX WTF?  Why purge here?  Why not purge others?  */
			cache_purge(tdvp);

		/*
		 * Make the target directory's entry for tcnp point at
		 * the source node.
		 */
		error = ext2fs_dirrewrite(VTOI(tdvp), tulr, VTOI(fvp), tcnp);
		if (error)
			goto whymustithurtsomuch;

		/*
		 * If the source and target are directories, and the
		 * target is in the same directory as the source,
		 * decrement the link count of the common parent
		 * directory, since we are removing the target from
		 * that directory.
		 */
		if (directory_p && !reparent_p) {
			KASSERT(fdvp == tdvp);
			/* XXX check, don't kassert */
			KASSERT(0 < VTOI(tdvp)->i_e2fs_nlink);
			VTOI(tdvp)->i_e2fs_nlink--;
			VTOI(tdvp)->i_flag |= IN_CHANGE;
		}

		/*
		 * Adjust the link count of the target to
		 * reflect the dirrewrite above.  If this is
		 * a directory it is empty and there are
		 * no links to it, so we can squash the inode and
		 * any space associated with it.  We disallowed
		 * renaming over top of a directory with links to
		 * it above, as the remaining link would point to
		 * a directory without "." or ".." entries.
		 */
		/* XXX check, don't kassert */
		KASSERT(0 < VTOI(tvp)->i_e2fs_nlink);
		VTOI(tvp)->i_e2fs_nlink--;
		if (directory_p) {
			/*
			 * XXX The ext2fs_dirempty call earlier does
			 * not guarantee anything about nlink.
			 */
			if (VTOI(tvp)->i_e2fs_nlink != 1)
				ufs_dirbad(VTOI(tvp), (doff_t)0,
				    "hard-linked directory");
			VTOI(tvp)->i_e2fs_nlink = 0;
			error = ext2fs_truncate(tvp, (off_t)0, IO_SYNC, cred);
		}
		VTOI(tvp)->i_flag |= IN_CHANGE;
	}

	/*
	 * ext2fs_direnter may compact the directory in the process of
	 * inserting a new entry.  That may invalidate fulr, which we
	 * need in order to remove the old entry.  In that case, we
	 * need to recalculate what fulr should be.
	 */
	if (!reparent_p && ulr_overlap(fulr, tulr))
		ext2fs_rename_unbotch_ulr_overlap(fdvp, fulr, tulr);

	/*
	 * 3) Unlink the source.
	 */

	/*
	 * If the source is a directory with a new parent, the link
	 * count of the old parent directory must be decremented and
	 * ".." set to point to the new parent.
	 */
	if (directory_p && reparent_p) {
		error = ext2fs_rename_replace_dotdot(fvp, fdvp, tdvp, cred);
		if (error)
			goto whymustithurtsomuch;

		/* XXX WTF?  Why purge here?  Why not purge others?  */
		cache_purge(fdvp);
	}

	error = ext2fs_dirremove(fdvp, fulr, fcnp);
	if (error)
		goto whymustithurtsomuch;

	genfs_rename_knote(fdvp, fvp, tdvp, tvp);

whymustithurtsomuch:
	KASSERT(0 < VTOI(fvp)->i_e2fs_nlink);
	VTOI(fvp)->i_e2fs_nlink--;
	VTOI(fvp)->i_flag |= IN_CHANGE;
	if (directory_p)
		VTOI(fvp)->i_flag &=~ IN_RENAME;
	return error;
}

static int
ext2fs_rename_unbotch_ulr_overlap(struct vnode *dvp,
    struct ufs_lookup_results *fulr, struct ufs_lookup_results *tulr)
{
	XXX			/* XXX */
}

/*
 * ext2fs_gro_remove: Rename an object over another link to itself,
 * effectively removing just the original link.
 */
static int
ext2fs_gro_remove(struct mount *mp, kauth_cred_t cred,
    struct vnode *dvp, struct componentname *cnp, void *de, struct vnode *vp)
{
	struct ufs_lookup_results *ulr = de;
	int error;

	KASSERT(mp != NULL);
	KASSERT(dvp != NULL);
	KASSERT(cnp != NULL);
	KASSERT(ulr != NULL);
	KASSERT(vp != NULL);
	KASSERT(dvp != vp);
	KASSERT(VOP_ISLOCKED(dvp) == LK_EXCLUSIVE);
	KASSERT(VOP_ISLOCKED(vp) == LK_EXCLUSIVE);

	error = ext2fs_dirremove(dvp, ulr, cnp);
	if (error)
		return error;

	KASSERT(0 < VTOI(vp)->i_e2fs_nlink);
	VTOI(vp)->i_e2fs_nlink--;
	VTOI(vp)->i_flag |= IN_CHANGE;

	return 0;
}

/*
 * ext2fs_gro_lookup: Look up and save the lookup results.
 */
static int
ext2fs_gro_lookup(struct mount *mp, struct vnode *dvp,
    struct componentname *cnp, void *de_ret, struct vnode **vp_ret)
{
	struct ufs_lookup_results *ulr_ret = de_ret;
	struct vnode *vp;
	int error;

	(void)mp;
	KASSERT(mp != NULL);
	KASSERT(dvp != NULL);
	KASSERT(cnp != NULL);
	KASSERT(ulr_ret != NULL);
	KASSERT(vp_ret != NULL);
	KASSERT(VOP_ISLOCKED(dvp) == LK_EXCLUSIVE);

	/* Kludge cargo-culted from dholland's ufs_rename.  */
	cnp->cn_flags |= (LOCKPARENT | LOCKLEAF);

	error = relookup(dvp, &vp, cnp);
	if ((error == 0) && (vp == NULL))
		error = ENOENT;
	if (error)
		return error;

	/*
	 * Thanks to VFS insanity, relookup locks vp, which screws us
	 * in various ways.
	 */
	VOP_UNLOCK(vp);

	*ulr_ret = VTOI(dvp)->i_crap;
	*vp_ret = vp;
	return 0;
}

/*
 * ext2fs_rmdired_p: Check whether the directory vp has been rmdired.
 *
 * vp must be locked and referenced.
 */
static bool
ext2fs_rmdired_p(struct vnode *vp)
{

	KASSERT(vp != NULL);
	KASSERT(VOP_ISLOCKED(vp) == LK_EXCLUSIVE);
	KASSERT(vp->v_type == VDIR);

	/* XXX Is this correct?  */
	return (VTOI(vp)->i_size == 0);
}

/*
 * ext2fs_gro_genealogy: Analyze the genealogy of the source and target
 * directories.
 */
static int
ext2fs_gro_genealogy(struct mount *mp,
    struct vnode *fdvp, struct vnode *tdvp,
    struct vnode **intermediate_node_ret)
{
	struct vnode *vp, *dvp;
	ino_t dotdot_ino;
	int error;

	KASSERT(mp != NULL);
	KASSERT(fdvp != NULL);
	KASSERT(tdvp != NULL);
	KASSERT(fdvp != tdvp);
	KASSERT(intermediate_node_ret != NULL);
	KASSERT(fdvp->v_mount == mp);
	KASSERT(tdvp->v_mount == mp);
	KASSERT(fdvp->v_type == VDIR);
	KASSERT(tdvp->v_type == VDIR);

	/*
	 * We need to provisionally lock tdvp to keep rmdir from
	 * deleting it -- or any ancestor -- at an inopportune moment.
	 * XXX This doesn't do the same thing as in tmpfs.  What to do?
	 */
	error = ext2fs_gro_lock_directory(mp, tdvp);
	if (error)
		return error;

	vp = tdvp;
	vref(vp);

	for (;;) {
		KASSERT(vp->v_type == VDIR);

		/* Did we hit the root without finding fdvp?  */
		if (VTOI(vp)->i_number == ROOTINO) {
			*intermediate_node_ret = NULL;
			break;
		}

		error = ext2fs_read_dotdot(vp, cred, &dotdot_ino);
		if (error)
			goto out;

		/* Did we find that fdvp is an ancestor?  */
		if (VTOI(fdvp)->i_number == dotdot_ino) {
			*intermediate_node_ret = vp;
			break;
		}

		/* Neither -- keep ascending.  */

		/*
		 * vput(vp);
		 * error = VFS_VGET(mp, dotdot_ino, &vp);
		 */

		/*
		 * XXX Cargo-culted from ufs_parentcheck...  Isn't
		 * there a race condition here?
		 */
		VOP_UNLOCK(vp);
		error = VFS_VGET(mp, dotdot_ino, &dvp);
		vrele(vp);
		if (error)
			return error;

		KASSERT(dvp != NULL);
		KASSERT(VOP_ISLOCKED(dvp) == LK_EXCLUSIVE);
		vp = dvp;

		if (vp->v_type != VDIR) {
			error = ENOTDIR;
			goto out;
		}

		/* XXX Is this the right way to test for rmdir?  */
		if (ext2fs_rmdired_p(vp)) {
			error = ENOENT;
			goto out;
		}
	}

	error = 0;
out:	vput(vp);
	return error;
}

/*
 * ext2fs_read_dotdot: Store in *ino_ret the inode number of the parent
 * of the directory vp.
 */
static int
ext2fs_read_dotdot(struct vnode *vp, kauth_cred_t cred, ino_t *ino_ret)
{
	struct ext2fs_dirtemplate dirbuf;
	int error;

	KASSERT(vp != NULL);
	KASSERT(ino_ret != NULL);
	KASSERT(vp->v_type == VDIR);

	error = vn_rdwr(UIO_READ, vp, &dirbuf, sizeof dirbuf, (off_t)0,
	    UIO_SYSSPACE, IO_NODELOCKED, cred, NULL, NULL);
	if (error)
		return error;

	if (dirbuf.dotdot_namlen != 2 ||
	    dirbuf.dotdot_name[0] != '.' ||
	    dirbuf.dotdot_name[1] != '.')
		return ENOTDIR;

	*ino_ret = fs2h32(dirbuf.dotdot_ino);
	return 0;
}

/*
 * ext2fs_rename_replace_dotdot: Change the target of the `..' entry of
 * the directory vp from fdvp to tdvp.
 */
static int
ext2fs_rename_replace_dotdot(struct vnode *vp,
    struct vnode *fdvp, struct vnode *tdvp,
    kauth_cred_t cred)
{
	struct ext2fs_dirtemplate dirbuf;
	int error;

	/* XXX Does it make sense to do this before the sanity checks below?  */
	KASSERT(0 < VTOI(fdvp)->i_e2fs_nlink);
	VTOI(fdvp)->i_e2fs_nlink--;
	VTOI(fdvp)->i_flag |= IN_CHANGE;

	error = vn_rdwr(UIO_READ, vp, &dirbuf, sizeof dirbuf, (off_t)0,
	    UIO_SYSSPACE, IO_NODELOCKED, cred, NULL, NULL);
	if (error)
		return error;

	if (dirbuf.dotdot_namlen != 2 ||
	    dirbuf.dotdot_name[0] != '.' ||
	    dirbuf.dotdot_name[1] != '.') {
		ufs_dirbad(VTOI(vp), (doff_t)12, "bad `..' entry");
		return 0;
	}

	if (fs2h32(dirbuf.dotdot_ino) != VTOI(fdvp)->i_number) {
		ufs_dirbad(VTOI(vp), (doff_t)12,
		    "`..' does not point at parent");
		return 0;
	}

	dirbuf.dotdot_ino = h2fs32(VTOI(tdvp)->i_number);
	/* XXX WTF?  Why not check error?  */
	(void)vn_rdwr(UIO_WRITE, vp, &dirbuf, sizeof dirbuf, (off_t)0,
	    UIO_SYSSPACE, (IO_NODELOCKED | IO_SYNC), cred, NULL, NULL);

	return 0;
}

/*
 * ext2fs_gro_lock_directory: Lock the directory vp, but fail if it has
 * been rmdir'd.
 */
static int
ext2fs_gro_lock_directory(struct mount *mp, struct vnode *vp)
{

	(void)mp;
	KASSERT(mp != NULL);
	KASSERT(vp != NULL);
	KASSERT(vp->v_mount == mp);

	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);

	if (ext2fs_rmdired_p(vp)) {
		VOP_UNLOCK(vp);
		return ENOENT;
	}

	return 0;
}

static const struct genfs_rename_ops ext2fs_genfs_rename_ops = {
	.gro_de_equal_p			= ext2fs_gro_de_equal_p,
	.gro_directory_empty_p		= ext2fs_gro_directory_empty_p,
	.gro_rename_check_possible	= ext2fs_gro_rename_check_possible,
	.gro_rename_check_permitted	= ext2fs_gro_rename_check_permitted,
	.gro_remove_check_possible	= ext2fs_gro_remove_check_possible,
	.gro_remove_check_permitted	= ext2fs_gro_remove_check_permitted,
	.gro_rename			= ext2fs_gro_rename,
	.gro_remove			= ext2fs_gro_remove,
	.gro_lookup			= ext2fs_gro_lookup,
	.gro_genealogy			= ext2fs_gro_genealogy,
	.gro_lock_directory		= ext2fs_gro_lock_directory,
};