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null.h revision 1.1.1.1 
      1 /*
      2  * Copyright (c) 1992, 1993
      3  *	The Regents of the University of California.  All rights reserved.
      4  *
      5  * This code is derived from software donated to Berkeley by
      6  * Jan-Simon Pendry.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in the
     15  *    documentation and/or other materials provided with the distribution.
     16  * 3. All advertising materials mentioning features or use of this software
     17  *    must display the following acknowledgement:
     18  *	This product includes software developed by the University of
     19  *	California, Berkeley and its contributors.
     20  * 4. Neither the name of the University nor the names of its contributors
     21  *    may be used to endorse or promote products derived from this software
     22  *    without specific prior written permission.
     23  *
     24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     34  * SUCH DAMAGE.
     35  *
     36  *	@(#)null.h	8.2 (Berkeley) 1/21/94
     37  *
     38  * $Id: null.h,v 1.1.1.1 1998/03/01 02:09:58 fvdl Exp $
     39  */
     40 
     41 struct null_args {
     42 	char		*target;	/* Target of loopback  */
     43 };
     44 
     45 struct null_mount {
     46 	struct mount	*nullm_vfs;
     47 	struct vnode	*nullm_rootvp;	/* Reference to root null_node */
     48 };
     49 
     50 #ifdef KERNEL
     51 /*
     52  * A cache of vnode references
     53  */
     54 struct null_node {
     55 	struct null_node	*null_forw;	/* Hash chain */
     56 	struct null_node	*null_back;
     57 	struct vnode	        *null_lowervp;	/* VREFed once */
     58 	struct vnode		*null_vnode;	/* Back pointer */
     59 };
     60 
     61 extern int null_node_create __P((struct mount *mp, struct vnode *target, struct vnode **vpp));
     62 
     63 #define	MOUNTTONULLMOUNT(mp) ((struct null_mount *)((mp)->mnt_data))
     64 #define	VTONULL(vp) ((struct null_node *)(vp)->v_data)
     65 #define	NULLTOV(xp) ((xp)->null_vnode)
     66 #ifdef NULLFS_DIAGNOSTIC
     67 extern struct vnode *null_checkvp __P((struct vnode *vp, char *fil, int lno));
     68 #define	NULLVPTOLOWERVP(vp) null_checkvp((vp), __FILE__, __LINE__)
     69 #else
     70 #define	NULLVPTOLOWERVP(vp) (VTONULL(vp)->null_lowervp)
     71 #endif
     72 
     73 extern int (**null_vnodeop_p)();
     74 extern struct vfsops null_vfsops;
     75 #endif /* KERNEL */
     76