188 lines
6.1 KiB
C
188 lines
6.1 KiB
C
/* $NetBSD: layer_subr.c,v 1.38 2020/04/13 19:23:19 ad Exp $ */
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/*
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* Copyright (c) 1999 National Aeronautics & Space Administration
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* All rights reserved.
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*
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* This software was written by William Studenmund of the
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* Numerical Aerospace Simulation Facility, NASA Ames Research Center.
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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. Neither the name of the National Aeronautics & Space Administration
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* nor the names of its contributors may be used to endorse or promote
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* products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NATIONAL AERONAUTICS & SPACE ADMINISTRATION
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE ADMINISTRATION OR CONTRIB-
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* UTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
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* OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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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. 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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* from: Id: lofs_subr.c,v 1.11 1992/05/30 10:05:43 jsp Exp
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* @(#)null_subr.c 8.7 (Berkeley) 5/14/95
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: layer_subr.c,v 1.38 2020/04/13 19:23:19 ad Exp $");
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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/time.h>
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#include <sys/vnode.h>
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#include <sys/mount.h>
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#include <sys/namei.h>
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#include <sys/kmem.h>
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#include <miscfs/genfs/layer.h>
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#include <miscfs/genfs/layer_extern.h>
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#ifdef LAYERFS_DIAGNOSTIC
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int layerfs_debug = 1;
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#endif
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/*
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* 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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void
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layerfs_init(void)
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{
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/* Nothing. */
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}
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void
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layerfs_done(void)
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{
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/* Nothing. */
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}
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/*
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* layer_node_create: try to find an existing layerfs vnode refering to it,
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* otherwise make a new vnode which contains a reference to the lower vnode.
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*/
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int
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layer_node_create(struct mount *mp, struct vnode *lowervp, struct vnode **nvpp)
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{
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int error;
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struct vnode *aliasvp;
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error = vcache_get(mp, &lowervp, sizeof(lowervp), &aliasvp);
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if (error)
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return error;
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/*
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* Now that we acquired a reference on the upper vnode, release one
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* on the lower node. The existence of the layer_node retains one
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* reference to the lower node.
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*/
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vrele(lowervp);
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KASSERT(vrefcnt(lowervp) > 0);
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#ifdef LAYERFS_DIAGNOSTIC
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if (layerfs_debug)
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vprint("layer_node_create: alias", aliasvp);
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#endif
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*nvpp = aliasvp;
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return 0;
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}
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#ifdef LAYERFS_DIAGNOSTIC
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struct vnode *
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layer_checkvp(struct vnode *vp, const char *fil, int lno)
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{
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struct layer_node *a = VTOLAYER(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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* WRS - no it doesnt...
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*/
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if (vp->v_op != layer_vnodeop_p) {
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printf ("layer_checkvp: on non-layer-node\n");
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#ifdef notyet
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while (layer_checkvp_barrier) /*WAIT*/ ;
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#endif
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panic("layer_checkvp");
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};
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#endif
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if (a->layer_lowervp == NULL) {
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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", 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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panic("layer_checkvp");
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}
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if (vrefcnt(a->layer_lowervp) < 1) {
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int i; u_long *p;
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printf("vp = %p, unref'ed lowervp\n", 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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panic ("layer with unref'ed lowervp");
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};
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#ifdef notnow
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printf("layer %p/%d -> %p/%d [%s, %d]\n",
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LAYERTOV(a), vrefcnt(LAYERTOV(a)),
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a->layer_lowervp, vrefcnt(a->layer_lowervp),
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fil, lno);
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#endif
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return a->layer_lowervp;
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}
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#endif
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