4451405fbd
Add correct support for v_object management, so mmap() operation should work properly. Add support for extattrctl() routine (submitted by semenu). At this point nullfs can be considered as functional and much more stable. In fact, it should behave as a "hard" "symlink" to underlying filesystem. Reviewed in general by: mckusick, dillon Parts of logic obtained from: NetBSD
342 lines
9.1 KiB
C
342 lines
9.1 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/kernel.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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struct lock null_hashlock;
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static MALLOC_DEFINE(M_NULLFSHASH, "NULLFS hash", "NULLFS hash table");
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MALLOC_DEFINE(M_NULLFSNODE, "NULLFS node", "NULLFS vnode private part");
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static int null_node_alloc(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(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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NULLFSDEBUG("nullfs_init\n"); /* printed during system boot */
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null_node_hashtbl = hashinit(NNULLNODECACHE, M_NULLFSHASH, &null_node_hash);
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lockinit(&null_hashlock, PVFS, "nullhs", 0, 0);
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return (0);
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}
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int
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nullfs_uninit(vfsp)
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struct vfsconf *vfsp;
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{
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if (null_node_hashtbl)
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free(null_node_hashtbl, M_NULLFSHASH);
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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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* Lower vnode should be locked on entry and will be left locked on exit.
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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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lockmgr(&null_hashlock, LK_EXCLUSIVE, NULL, p);
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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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lockmgr(&null_hashlock, LK_RELEASE, NULL, p);
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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, LK_EXCLUSIVE | LK_CANRECURSE, 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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/*
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* Now we got both vnodes locked, so release the
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* lower one.
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*/
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VOP_UNLOCK(lowervp, 0, p);
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return (vp);
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}
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}
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lockmgr(&null_hashlock, LK_RELEASE, NULL, p);
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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 proc *p = curproc; /* XXX */
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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),
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M_NULLFSNODE, 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_NULLFSNODE);
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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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vp->v_data = NULL;
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FREE(xp, M_NULLFSNODE);
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vp->v_type = VBAD; /* node is discarded */
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vrele(vp);
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*vpp = othervp;
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return 0;
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};
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/*
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* From NetBSD:
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* Now lock the new node. We rely on the fact that we were passed
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* a locked vnode. If the lower node is exporting a struct lock
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* (v_vnlock != NULL) then we just set the upper v_vnlock to the
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* lower one, and both are now locked. If the lower node is exporting
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* NULL, then we copy that up and manually lock the new vnode.
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*/
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lockmgr(&null_hashlock, LK_EXCLUSIVE, NULL, p);
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vp->v_vnlock = lowervp->v_vnlock;
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error = VOP_LOCK(vp, LK_EXCLUSIVE | LK_THISLAYER, p);
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if (error)
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panic("null_node_alloc: can't lock new vnode\n");
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VREF(lowervp);
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hd = NULL_NHASH(lowervp);
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LIST_INSERT_HEAD(hd, xp, null_hash);
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lockmgr(&null_hashlock, LK_RELEASE, NULL, p);
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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 to the given underlying
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* vnode (which should be locked). If no vnode found, create a new null_node
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* vnode which 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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vrele(lowervp);
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#ifdef NULLFS_DEBUG
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vprint("null_node_create: exists", aliasvp);
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#endif
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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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NULLFSDEBUG("null_node_create: create new alias vnode\n");
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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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#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 NULLFS_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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