59f305606c
initializations but we did have lofty goals and big ideals. Adjust to more contemporary circumstances and gain type checking. Replace the entire vop_t frobbing thing with properly typed structures. The only casualty is that we can not add a new VOP_ method with a loadable module. History has not given us reason to belive this would ever be feasible in the the first place. Eliminate in toto VOCALL(), vop_t, VNODEOP_SET() etc. Give coda correct prototypes and function definitions for all vop_()s. Generate a bit more data from the vnode_if.src file: a struct vop_vector and protype typedefs for all vop methods. Add a new vop_bypass() and make vop_default be a pointer to another struct vop_vector. Remove a lot of vfs_init since vop_vector is ready to use from the compiler. Cast various vop_mumble() to void * with uppercase name, for instance VOP_PANIC, VOP_NULL etc. Implement VCALL() by making vdesc_offset the offsetof() the relevant function pointer in vop_vector. This is disgusting but since the code is generated by a script comparatively safe. The alternative for nullfs etc. would be much worse. Fix up all vnode method vectors to remove casts so they become typesafe. (The bulk of this is generated by scripts)
362 lines
9.6 KiB
C
362 lines
9.6 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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* 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/lock.h>
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#include <sys/mutex.h>
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#include <sys/malloc.h>
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#include <sys/mount.h>
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#include <sys/proc.h>
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#include <sys/vnode.h>
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#include <fs/nullfs/null.h>
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#define LOG2_SIZEVNODE 8 /* 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 mtx null_hashmtx;
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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 struct vnode * null_hashget(struct mount *, struct vnode *);
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static struct vnode * null_hashins(struct mount *, struct null_node *);
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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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mtx_init(&null_hashmtx, "nullhs", NULL, MTX_DEF);
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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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mtx_destroy(&null_hashmtx);
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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_hashget(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 thread *td = curthread; /* 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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mtx_lock(&null_hashmtx);
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LIST_FOREACH(a, hd, null_hash) {
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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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mtx_lock(&vp->v_interlock);
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/*
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* Don't block if nullfs vnode is being recycled.
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* We already hold a lock on the lower vnode, thus
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* waiting might deadlock against the thread
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* recycling the nullfs vnode or another thread
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* in vrele() waiting for the vnode lock.
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*/
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if ((vp->v_iflag & VI_XLOCK) != 0) {
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VI_UNLOCK(vp);
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continue;
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}
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mtx_unlock(&null_hashmtx);
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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_THISLAYER | LK_INTERLOCK, td))
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goto loop;
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return (vp);
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}
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}
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mtx_unlock(&null_hashmtx);
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return (NULLVP);
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}
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/*
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* Act like null_hashget, but add passed null_node to hash if no existing
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* node found.
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*/
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static struct vnode *
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null_hashins(mp, xp)
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struct mount *mp;
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struct null_node *xp;
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{
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struct thread *td = curthread; /* XXX */
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struct null_node_hashhead *hd;
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struct null_node *oxp;
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struct vnode *ovp;
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hd = NULL_NHASH(xp->null_lowervp);
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loop:
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mtx_lock(&null_hashmtx);
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LIST_FOREACH(oxp, hd, null_hash) {
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if (oxp->null_lowervp == xp->null_lowervp &&
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NULLTOV(oxp)->v_mount == mp) {
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ovp = NULLTOV(oxp);
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mtx_lock(&ovp->v_interlock);
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/*
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* Don't block if nullfs vnode is being recycled.
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* We already hold a lock on the lower vnode, thus
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* waiting might deadlock against the thread
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* recycling the nullfs vnode or another thread
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* in vrele() waiting for the vnode lock.
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*/
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if ((ovp->v_iflag & VI_XLOCK) != 0) {
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VI_UNLOCK(ovp);
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continue;
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}
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mtx_unlock(&null_hashmtx);
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if (vget(ovp, LK_EXCLUSIVE | LK_THISLAYER | LK_INTERLOCK, td))
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goto loop;
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return (ovp);
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}
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}
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LIST_INSERT_HEAD(hd, xp, null_hash);
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mtx_unlock(&null_hashmtx);
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return (NULLVP);
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}
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/*
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* Make a new or get existing nullfs node.
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* Vp is the alias vnode, lowervp is the lower vnode.
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*
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* The lowervp assumed to be locked and having "spare" reference. This routine
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* vrele lowervp if nullfs node was taken from hash. Otherwise it "transfers"
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* the caller's "spare" reference to created nullfs vnode.
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*/
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int
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null_nodeget(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 thread *td = curthread; /* XXX */
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struct null_node *xp;
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struct vnode *vp;
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int error;
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/* Lookup the hash firstly */
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*vpp = null_hashget(mp, lowervp);
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if (*vpp != NULL) {
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vrele(lowervp);
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return (0);
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}
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/*
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* We do not serialize vnode creation, instead we will check for
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* duplicates later, when adding new vnode to hash.
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*
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* Note that duplicate can only appear in hash if the lowervp is
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* locked LK_SHARED.
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*/
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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("null", mp, &null_vnodeops, &vp);
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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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xp->null_vnode = vp;
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xp->null_lowervp = lowervp;
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xp->null_pending_locks = 0;
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xp->null_drain_wakeup = 0;
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vp->v_type = lowervp->v_type;
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vp->v_data = xp;
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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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vp->v_vnlock = lowervp->v_vnlock;
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error = VOP_LOCK(vp, LK_EXCLUSIVE | LK_THISLAYER, td);
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if (error)
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panic("null_nodeget: can't lock new vnode\n");
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/*
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* Atomically insert our new node into the hash or vget existing
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* if someone else has beaten us to it.
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*/
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*vpp = null_hashins(mp, xp);
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if (*vpp != NULL) {
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vrele(lowervp);
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VOP_UNLOCK(vp, LK_THISLAYER, td);
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vp->v_vnlock = NULL;
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xp->null_lowervp = NULL;
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vrele(vp);
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return (0);
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}
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/*
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* XXX We take extra vref just to workaround UFS's XXX:
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* UFS can vrele() vnode in VOP_CLOSE() in some cases. Luckily, this
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* can only happen if v_usecount == 1. To workaround, we just don't
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* let v_usecount be 1, it will be 2 or more.
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*/
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VREF(lowervp);
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*vpp = vp;
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return (0);
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}
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/*
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* Remove node from hash.
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*/
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void
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null_hashrem(xp)
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struct null_node *xp;
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{
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mtx_lock(&null_hashmtx);
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LIST_REMOVE(xp, null_hash);
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mtx_unlock(&null_hashmtx);
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}
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#ifdef DIAGNOSTIC
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#ifdef KDB
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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 (vrefcnt(a->null_lowervp) < 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), vrefcnt(NULLTOV(a)),
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a->null_lowervp, vrefcnt(a->null_lowervp),
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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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