a0f40f54aa
the other XXXFS_DIAGNOSTIC options (not very) and mostly controlled tracing of normal operation. Use `#ifdef DEBUG' for non-diagnostics and `#ifdef DIAGNOSTIC' for diagnostics.
302 lines
7.8 KiB
C
302 lines
7.8 KiB
C
/*
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* Copyright (c) 1992, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software donated to Berkeley by
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* Jan-Simon Pendry.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)null_subr.c 8.7 (Berkeley) 5/14/95
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*
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* $FreeBSD$
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/proc.h>
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#include <sys/vnode.h>
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#include <sys/mount.h>
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#include <sys/malloc.h>
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#include <miscfs/nullfs/null.h>
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#define LOG2_SIZEVNODE 7 /* log2(sizeof struct vnode) */
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#define NNULLNODECACHE 16
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/*
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* Null layer cache:
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* Each cache entry holds a reference to the lower vnode
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* along with a pointer to the alias vnode. When an
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* entry is added the lower vnode is VREF'd. When the
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* alias is removed the lower vnode is vrele'd.
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*/
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#define NULL_NHASH(vp) \
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(&null_node_hashtbl[(((uintptr_t)vp)>>LOG2_SIZEVNODE) & null_node_hash])
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static LIST_HEAD(null_node_hashhead, null_node) *null_node_hashtbl;
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static u_long null_node_hash;
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static int null_node_alloc __P((struct mount *mp, struct vnode *lowervp,
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struct vnode **vpp));
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static struct vnode *
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null_node_find __P((struct mount *mp, struct vnode *lowervp));
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/*
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* Initialise cache headers
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*/
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int
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nullfs_init(vfsp)
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struct vfsconf *vfsp;
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{
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#ifdef DEBUG
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printf("nullfs_init\n"); /* printed during system boot */
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#endif
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null_node_hashtbl = hashinit(NNULLNODECACHE, M_CACHE, &null_node_hash);
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return (0);
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}
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/*
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* Return a VREF'ed alias for lower vnode if already exists, else 0.
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*/
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static struct vnode *
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null_node_find(mp, lowervp)
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struct mount *mp;
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struct vnode *lowervp;
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{
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struct proc *p = curproc; /* XXX */
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struct null_node_hashhead *hd;
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struct null_node *a;
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struct vnode *vp;
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/*
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* Find hash base, and then search the (two-way) linked
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* list looking for a null_node structure which is referencing
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* the lower vnode. If found, the increment the null_node
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* reference count (but NOT the lower vnode's VREF counter).
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*/
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hd = NULL_NHASH(lowervp);
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loop:
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for (a = hd->lh_first; a != 0; a = a->null_hash.le_next) {
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if (a->null_lowervp == lowervp && NULLTOV(a)->v_mount == mp) {
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vp = NULLTOV(a);
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/*
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* We need vget for the VXLOCK
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* stuff, but we don't want to lock
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* the lower node.
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*/
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if (vget(vp, 0, p)) {
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printf ("null_node_find: vget failed.\n");
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goto loop;
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};
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return (vp);
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}
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}
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return NULLVP;
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}
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/*
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* Make a new null_node node.
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* Vp is the alias vnode, lofsvp is the lower vnode.
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* Maintain a reference to (lowervp).
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*/
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static int
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null_node_alloc(mp, lowervp, vpp)
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struct mount *mp;
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struct vnode *lowervp;
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struct vnode **vpp;
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{
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struct null_node_hashhead *hd;
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struct null_node *xp;
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struct vnode *othervp, *vp;
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int error;
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/*
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* Do the MALLOC before the getnewvnode since doing so afterward
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* might cause a bogus v_data pointer to get dereferenced
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* elsewhere if MALLOC should block.
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*/
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MALLOC(xp, struct null_node *, sizeof(struct null_node), M_TEMP, M_WAITOK);
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error = getnewvnode(VT_NULL, mp, null_vnodeop_p, vpp);
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if (error) {
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FREE(xp, M_TEMP);
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return (error);
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}
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vp = *vpp;
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vp->v_type = lowervp->v_type;
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xp->null_vnode = vp;
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vp->v_data = xp;
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xp->null_lowervp = lowervp;
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/*
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* Before we insert our new node onto the hash chains,
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* check to see if someone else has beaten us to it.
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* (We could have slept in MALLOC.)
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*/
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othervp = null_node_find(mp, lowervp);
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if (othervp) {
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FREE(xp, M_TEMP);
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vp->v_type = VBAD; /* node is discarded */
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vp->v_usecount = 0; /* XXX */
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*vpp = othervp;
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return 0;
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};
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VREF(lowervp); /* Extra VREF will be vrele'd in null_node_create */
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hd = NULL_NHASH(lowervp);
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LIST_INSERT_HEAD(hd, xp, null_hash);
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return 0;
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}
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/*
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* Try to find an existing null_node vnode refering
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* to it, otherwise make a new null_node vnode which
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* contains a reference to the lower vnode.
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*/
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int
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null_node_create(mp, lowervp, newvpp)
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struct mount *mp;
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struct vnode *lowervp;
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struct vnode **newvpp;
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{
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struct vnode *aliasvp;
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aliasvp = null_node_find(mp, lowervp);
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if (aliasvp) {
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/*
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* null_node_find has taken another reference
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* to the alias vnode.
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*/
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#ifdef DEBUG
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vprint("null_node_create: exists", aliasvp);
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#endif
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/* VREF(aliasvp); --- done in null_node_find */
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} else {
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int error;
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/*
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* Get new vnode.
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*/
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#ifdef DEBUG
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printf("null_node_create: create new alias vnode\n");
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#endif
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/*
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* Make new vnode reference the null_node.
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*/
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error = null_node_alloc(mp, lowervp, &aliasvp);
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if (error)
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return error;
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/*
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* aliasvp is already VREF'd by getnewvnode()
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*/
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}
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vrele(lowervp);
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#ifdef DIAGNOSTIC
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if (lowervp->v_usecount < 1) {
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/* Should never happen... */
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vprint ("null_node_create: alias ", aliasvp);
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vprint ("null_node_create: lower ", lowervp);
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panic ("null_node_create: lower has 0 usecount.");
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};
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#endif
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#ifdef DEBUG
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vprint("null_node_create: alias", aliasvp);
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vprint("null_node_create: lower", lowervp);
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#endif
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*newvpp = aliasvp;
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return (0);
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}
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#ifdef DIAGNOSTIC
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#include "opt_ddb.h"
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#ifdef DDB
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#define null_checkvp_barrier 1
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#else
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#define null_checkvp_barrier 0
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#endif
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struct vnode *
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null_checkvp(vp, fil, lno)
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struct vnode *vp;
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char *fil;
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int lno;
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{
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struct null_node *a = VTONULL(vp);
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#ifdef notyet
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/*
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* Can't do this check because vop_reclaim runs
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* with a funny vop vector.
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*/
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if (vp->v_op != null_vnodeop_p) {
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printf ("null_checkvp: on non-null-node\n");
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while (null_checkvp_barrier) /*WAIT*/ ;
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panic("null_checkvp");
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};
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#endif
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if (a->null_lowervp == NULLVP) {
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/* Should never happen */
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int i; u_long *p;
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printf("vp = %p, ZERO ptr\n", (void *)vp);
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for (p = (u_long *) a, i = 0; i < 8; i++)
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printf(" %lx", p[i]);
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printf("\n");
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/* wait for debugger */
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while (null_checkvp_barrier) /*WAIT*/ ;
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panic("null_checkvp");
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}
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if (a->null_lowervp->v_usecount < 1) {
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int i; u_long *p;
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printf("vp = %p, unref'ed lowervp\n", (void *)vp);
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for (p = (u_long *) a, i = 0; i < 8; i++)
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printf(" %lx", p[i]);
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printf("\n");
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/* wait for debugger */
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while (null_checkvp_barrier) /*WAIT*/ ;
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panic ("null with unref'ed lowervp");
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};
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#ifdef notyet
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printf("null %x/%d -> %x/%d [%s, %d]\n",
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NULLTOV(a), NULLTOV(a)->v_usecount,
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a->null_lowervp, a->null_lowervp->v_usecount,
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fil, lno);
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#endif
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return a->null_lowervp;
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}
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#endif
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