/*	$NetBSD$	*/

/*-
 * Copyright (c) 2014 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Taylor R Campbell.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * XXX NOTE NOTE NOTE XXX
 *
 * This code does not actually work.  It is a draft of an idea.  It
 * probably won't even compile, even if you make it include the right
 * header files.
 */

/* inode->vnode table */

struct vinotab {
	krwlock_t	vit_lock;
	rb_tree_t	vit_tree;
};

struct vinokey {
	const void	*vik_key;
	unsigned int	vik_keysize;
};

static int
compare_vinoents(void *context __unused, const void *va, const void *vb)
{
	const struct vinoent *const a = va;
	const struct vinoent *const b = vb;

	if (a->vie_keysize < b->vie_keysize)
		return -1;
	if (a->vie_keysize > b->vie_keysize)
		return +1;
	return memcmp(a->vie_key, b->vie_key, a->vie_keysize);
}

static int
compare_vinoent_key(void *context __unused, const void *ve, const void *vk)
{
	const struct vionent *const e = ve;
	const struct vinokey *const k = vk;

	if (e->vie_keysize < k->vik_keysize)
		return -1;
	if (e->vie_keysize > k->vik_keysize)
		return +1;
	return memcmp(e->vie_key, k->vik_key, e->vie_keysize);
}

static const rb_tree_ops_t viontab_rb_ops = {
	.rbto_compare_nodes_fn = &compare_vinoents,
	.rbto_compare_key_fn = &compare_vinoent_key,
	.rbto_node_offset = offsetof(struct vinoent, vie_rb_node),
	.rbto_context = NULL,
};

struct vinotab *
vinotab_create(void)
{
	struct vinotab *const vinotab = kmem_alloc(sizeof(*vinotab), KM_SLEEP);

	rw_init(&vinotab->vit_lock);
	rb_tree_init(&vinotab->vit_tree, &vinotab_rb_ops);

	return vinotab;
}

void
vinotab_destroy(struct vinotab *vinotab)
{

	KASSERT(RB_TREE_MIN(vinotab->vit_tree) == NULL);

#if 0
	rb_tree_destroy(&vinotab->vit_tree);
#endif
	rw_destroy(&vinotab->vit_lock);

	kmem_free(vinotab, sizeof(*vinotab));
}

void
vinotab_reinit(struct vinotab *vinotab __unused)
{
}

int
vinotab_get(struct vinotab *vinotab, const void *key, unsigned int keysize,
    int flags, struct vnode *vpp)
{
	struct vinoent *vinoent;
	struct vinokey vinokey = { .vik_key = key, .vik_keysize = keysize };
	int error;

	rw_enter(&vinotab->vit_lock, RW_READER);
	vinoent = rb_tree_find_node(&vinotab->vit_tree, &vinokey);
	if (vinoent != NULL) {
		vpreget(vinoent->vie_vnode);
		rw_exit(&vinotab->vit_lock);
		error = vget(vinoent->vie_vnode, flags);
		if (error) {
			*vpp = NULL;
			return error;
		}
		*vpp = vinoent->vie_vnode;
		return 0;
	}
	rw_exit(&vinotab->vit_lock);

	*vpp = NULL;
	return ENOENT;
}

int
vinotab_intern(struct vinotab *vinotab, struct vinoent *new_vinoent,
    const void *key, unsigned int keysize, struct vnode *vp, int flags,
    struct vnode **vpp)
{
	struct vinoent *vinoent;

	new_vinoent->vie_vnode = vp;
	new_vinoent->vie_key = key;
	new_vinoent->vie_keysize = keysize;

retry:	rw_enter(&vinotab->vit_lock, RW_WRITER);
	vinoent = rb_tree_insert_node(&vinotab->vit_tree, new_vinoent);
	if (vinoent != NULL) {
		vpreget(vinoent->vie_vnode);
		rw_exit(&vinotab->vit_lock);
		error = vget(vinoent->vie_node, flags);
		if (error) {
			if (error == ENOENT)
				goto retry;
			*vpp = NULL;
			return error;
		}
		*vpp = vinoent->vie_node;
		return 0;
	}
	rw_exit(&vinotab->vit_lock);

	*vpp = vp;
	return 0;
}

void
vinotab_remove(struct vinotab *vinotab, struct vinoent *vinoent)
{

	rw_enter(&vinotab->vit_lock, RW_WRITER);
	rb_tree_remove_node(&viontab->vit_tree, vinoent);
	rw_exit(&vinotab->vit_lock);
}