/*	$NetBSD$	*/

/*-
 * 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.
 */

int
layer_node_create(struct mount *mp, struct vnode *lowervp, struct vnode *vpp)
{
	struct layer_mount *lmp = MOUNTTOLAYERMOUNT(mp);
	struct vnode *vp = NULL;
	int error;

	/*
	 * Try to get an existing vnode for the lower vnode.
	 */
	error = vinotab_get(lmp->lm_vinotab, &lowervp, sizeof(lowervp),
	    VGET_INTR, &vp);
	KASSERT((error == 0) == (vp != NULL));
	if (error != ENOENT)
		goto out;

	/*
	 * Nothing there.  Try to allocate one.
	 */
	error = (*lmp->layerm_alloc)(mp, lowervp, &vp);
	KASSERT((error == 0) == (vp != NULL));
	if (error)
		goto out;

	/*
	 * vp has a reference to lowervp, and we shall use vp
	 * henceforth, so drop our reference to lowervp.
	 *
	 * XXX Caller should do this, not us...
	 */
	vrele(lowervp);
	KASSERT(0 < lowervp->v_usecount);
	error = 0;

out:	*vpp = vp;
	return error;
}

int
layer_node_alloc(struct mount *mp, struct vnode *lowervp,
    struct vnode *vpp)
{
	struct layer_mount *lmp = MOUNTTOLAYERMOUNT(mp);
	struct vnode *vp = NULL, *vp0 = NULL;
	struct layer_node *xp;
	int error;

	/*
	 * Create a new vnode for this lower vnode.
	 */
	error = getnewvnode(lmp->layerm_tag, mp, lmp->layerm_vnodeop_p,
	    lowervp->v_interlock, &vp);
	KASSERT((error == 0) == (vp != NULL));
	if (error)
		goto out;

	/*
	 * Create a layer node for it and fill it in just enough for a
	 * lookup.
	 */
	xp = kmem_zalloc(lmp->layerm_size, KM_SLEEP);
	KASSERT(xp != NULL);
	xp->layer_lowervp = lowervp;

	/*
	 * Try to put this vnode in the table for the lower vnode.  If
	 * someone else beat us to it, release ours and use theirs
	 * instead.
	 */
	error = vinotab_intern(lmp->lm_vinotab, &xp->layer_vinoent,
	    &xp->layer_lowervp, sizeof(xp->layer_lowervp), vp, &vp0);
	KASSERT((error == 0) == (vp0 != NULL));
	if (vp0 != vp) {
		kmem_free(xp, lmp->layerm_size);
		ungetnewvnode(vp);
		vp = vp0;
		goto out;
	}

	/*
	 * Set up the layer node.
	 */
	vref(lowervp);
	xp->layer_flags = 0;

	/*
	 * Set up the vnode.
	 */
	vp->v_data = xp;
	vp->v_vflag &= ~VV_MPSAFE;
	vp->v_vflag |= (lowervp->v_vflag && VV_MPSAFE);

	vp->v_type = lowervp->v_type;
	if ((vp->v_type == VBLK) || (vp->v_type == VCHR))
		spec_node_init(vp, lowervp->v_rdev);

	mutex_enter(vp->v_interlock);
	vp->v_iflag |= VI_LAYER;
	mutex_exit(vp->v_interlock);

	/*
	 * Set the inode size.  (XXX Why shouldn't we leave this
	 * VSIZENOTSET as it is initialized to be?  Are users
	 * guaranteed to reinitialize it?)
	 */
	uvm_vnp_setsize(vp, 0);

	/*
	 * All set.  Mark it ready to go and wake anyone waiting.
	 */
	vready(vp);
	error = 0;

out:	*vpp = vp;
	return error;
}

int
layer_reclaim(void *v)
{
	struct vop_reclaim_args /* {
		struct vnode *a_vp;
	} */ *ap = v;
	struct vnode *vp = ap->a_vp;
	struct layer_mount *lmp = MOUNTTOLAYERMOUNT(vp->v_mount);
	struct layer_node *xp = VTOLAYER(vp);
	struct vonde *lowervp = xp->layer_lowervp;

	/* XXX Nobody else does this.  Why should layerfs?  */
	if (vp == lmp->layerm_rootvp)
		lmp->layerm_rootvp = NULL;

	vinotab_remove(lmp->lm_vinotab, &xp->layer_vinoent);
	xp->layer_lowervp = NULL;

	kmem_free(xp, lmp->layerm_size);
	vp->v_data = NULL;

	vrele(lowervp);

	return 0;
}