null.h

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1992, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software donated to Berkeley by
 * Jan-Simon Pendry.
 *
 * 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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 */

#ifndef	FS_NULL_H
#define	FS_NULL_H

#include <sys/ck.h>
#include <vm/uma.h>

#define	NULLM_CACHE		0x0001
#define	NULLM_NOUNPBYPASS	0x0002

struct null_mount {
	struct mount	*nullm_vfs;
	struct vnode	*nullm_lowerrootvp;	/* Ref to lower root vnode */
	uint64_t	nullm_flags;
	struct mount_upper_node upper_node;
	struct mount_upper_node notify_node;
};

#ifdef _KERNEL
/*
 * A cache of vnode references
 */
struct null_node {
	CK_SLIST_ENTRY(null_node) null_hash;	/* Hash list */
	struct vnode	        *null_lowervp;	/* VREFed once */
	struct vnode		*null_vnode;	/* Back pointer */
	u_int			null_flags;
};

#define	NULLV_NOUNLOCK	0x0001
#define	NULLV_DROP	0x0002

#define	MOUNTTONULLMOUNT(mp) ((struct null_mount *)((mp)->mnt_data))
#define	VTONULL(vp) ((struct null_node *)(vp)->v_data)
#define	VTONULL_SMR(vp) ((struct null_node *)vn_load_v_data_smr(vp))
#define	NULLTOV(xp) ((xp)->null_vnode)

int nullfs_init(struct vfsconf *vfsp);
int nullfs_uninit(struct vfsconf *vfsp);
int null_nodeget(struct mount *mp, struct vnode *target, struct vnode **vpp);
struct vnode *null_hashget(struct mount *mp, struct vnode *lowervp);
void null_hashrem(struct null_node *xp);
int null_bypass(struct vop_generic_args *ap);

#ifdef DIAGNOSTIC
struct vnode *null_checkvp(struct vnode *vp, char *fil, int lno);
#define	NULLVPTOLOWERVP(vp) null_checkvp((vp), __FILE__, __LINE__)
#else
#define	NULLVPTOLOWERVP(vp) (VTONULL(vp)->null_lowervp)
#endif

extern struct vop_vector null_vnodeops;
extern struct vop_vector null_vnodeops_no_unp_bypass;

static inline bool
null_is_nullfs_vnode(struct vnode *vp)
{
	const struct vop_vector *op;

	op = vp->v_op;
	return (op == &null_vnodeops || op == &null_vnodeops_no_unp_bypass);
}

extern uma_zone_t null_node_zone;

#ifdef NULLFS_DEBUG
#define NULLFSDEBUG(format, args...) printf(format ,## args)
#else
#define NULLFSDEBUG(format, args...)
#endif /* NULLFS_DEBUG */

#endif /* _KERNEL */

#endif