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layer_subr.c
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layer_subr.c
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/* $NetBSD: layer_subr.c,v 1.39 2022/04/10 09:50:46 andvar Exp $ */
/*
* Copyright (c) 1999 National Aeronautics & Space Administration
* All rights reserved.
*
* This software was written by William Studenmund of the
* Numerical Aerospace Simulation Facility, NASA Ames Research Center.
*
* 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 National Aeronautics & Space Administration
* 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 NATIONAL AERONAUTICS & SPACE ADMINISTRATION
* ``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 ADMINISTRATION OR CONTRIB-
* UTORS 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.
*/
/*
* 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.
*
* from: Id: lofs_subr.c,v 1.11 1992/05/30 10:05:43 jsp Exp
* @(#)null_subr.c 8.7 (Berkeley) 5/14/95
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: layer_subr.c,v 1.39 2022/04/10 09:50:46 andvar Exp $");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/time.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/kmem.h>
#include <miscfs/genfs/layer.h>
#include <miscfs/genfs/layer_extern.h>
#ifdef LAYERFS_DIAGNOSTIC
int layerfs_debug = 1;
#endif
/*
* layer cache:
* Each cache entry holds a reference to the lower vnode
* along with a pointer to the alias vnode. When an
* entry is added the lower vnode is VREF'd. When the
* alias is removed the lower vnode is vrele'd.
*/
void
layerfs_init(void)
{
/* Nothing. */
}
void
layerfs_done(void)
{
/* Nothing. */
}
/*
* layer_node_create: try to find an existing layerfs vnode referring to it,
* otherwise make a new vnode which contains a reference to the lower vnode.
*/
int
layer_node_create(struct mount *mp, struct vnode *lowervp, struct vnode **nvpp)
{
int error;
struct vnode *aliasvp;
error = vcache_get(mp, &lowervp, sizeof(lowervp), &aliasvp);
if (error)
return error;
/*
* Now that we acquired a reference on the upper vnode, release one
* on the lower node. The existence of the layer_node retains one
* reference to the lower node.
*/
vrele(lowervp);
KASSERT(vrefcnt(lowervp) > 0);
#ifdef LAYERFS_DIAGNOSTIC
if (layerfs_debug)
vprint("layer_node_create: alias", aliasvp);
#endif
*nvpp = aliasvp;
return 0;
}
#ifdef LAYERFS_DIAGNOSTIC
struct vnode *
layer_checkvp(struct vnode *vp, const char *fil, int lno)
{
struct layer_node *a = VTOLAYER(vp);
#ifdef notyet
/*
* Can't do this check because vop_reclaim runs
* with a funny vop vector.
*
* WRS - no it doesnt...
*/
if (vp->v_op != layer_vnodeop_p) {
printf ("layer_checkvp: on non-layer-node\n");
#ifdef notyet
while (layer_checkvp_barrier) /*WAIT*/ ;
#endif
panic("layer_checkvp");
};
#endif
if (a->layer_lowervp == NULL) {
/* Should never happen */
int i; u_long *p;
printf("vp = %p, ZERO ptr\n", vp);
for (p = (u_long *) a, i = 0; i < 8; i++)
printf(" %lx", p[i]);
printf("\n");
/* wait for debugger */
panic("layer_checkvp");
}
if (vrefcnt(a->layer_lowervp) < 1) {
int i; u_long *p;
printf("vp = %p, unref'ed lowervp\n", vp);
for (p = (u_long *) a, i = 0; i < 8; i++)
printf(" %lx", p[i]);
printf("\n");
/* wait for debugger */
panic ("layer with unref'ed lowervp");
};
#ifdef notnow
printf("layer %p/%d -> %p/%d [%s, %d]\n",
LAYERTOV(a), vrefcnt(LAYERTOV(a)),
a->layer_lowervp, vrefcnt(a->layer_lowervp),
fil, lno);
#endif
return a->layer_lowervp;
}
#endif