340 lines
8.9 KiB
C
340 lines
8.9 KiB
C
/*
|
|
* 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. All advertising materials mentioning features or use of this software
|
|
* must display the following acknowledgement:
|
|
* This product includes software developed by the University of
|
|
* California, Berkeley and its contributors.
|
|
* 4. 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.
|
|
*
|
|
* @(#)null_subr.c 8.7 (Berkeley) 5/14/95
|
|
*
|
|
* $FreeBSD$
|
|
*/
|
|
|
|
#include <sys/param.h>
|
|
#include <sys/systm.h>
|
|
#include <sys/kernel.h>
|
|
#include <sys/lock.h>
|
|
#include <sys/mutex.h>
|
|
#include <sys/malloc.h>
|
|
#include <sys/mount.h>
|
|
#include <sys/proc.h>
|
|
#include <sys/vnode.h>
|
|
|
|
#include <fs/nullfs/null.h>
|
|
|
|
#define LOG2_SIZEVNODE 7 /* log2(sizeof struct vnode) */
|
|
#define NNULLNODECACHE 16
|
|
|
|
/*
|
|
* Null 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.
|
|
*/
|
|
|
|
#define NULL_NHASH(vp) \
|
|
(&null_node_hashtbl[(((uintptr_t)vp)>>LOG2_SIZEVNODE) & null_node_hash])
|
|
|
|
static LIST_HEAD(null_node_hashhead, null_node) *null_node_hashtbl;
|
|
static u_long null_node_hash;
|
|
struct mtx null_hashmtx;
|
|
|
|
static MALLOC_DEFINE(M_NULLFSHASH, "NULLFS hash", "NULLFS hash table");
|
|
MALLOC_DEFINE(M_NULLFSNODE, "NULLFS node", "NULLFS vnode private part");
|
|
|
|
static struct vnode * null_hashget(struct vnode *);
|
|
static struct vnode * null_hashins(struct null_node *);
|
|
|
|
/*
|
|
* Initialise cache headers
|
|
*/
|
|
int
|
|
nullfs_init(vfsp)
|
|
struct vfsconf *vfsp;
|
|
{
|
|
|
|
NULLFSDEBUG("nullfs_init\n"); /* printed during system boot */
|
|
null_node_hashtbl = hashinit(NNULLNODECACHE, M_NULLFSHASH, &null_node_hash);
|
|
mtx_init(&null_hashmtx, "nullhs", NULL, MTX_DEF);
|
|
return (0);
|
|
}
|
|
|
|
int
|
|
nullfs_uninit(vfsp)
|
|
struct vfsconf *vfsp;
|
|
{
|
|
|
|
mtx_destroy(&null_hashmtx);
|
|
free(null_node_hashtbl, M_NULLFSHASH);
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Return a VREF'ed alias for lower vnode if already exists, else 0.
|
|
* Lower vnode should be locked on entry and will be left locked on exit.
|
|
*/
|
|
static struct vnode *
|
|
null_hashget(lowervp)
|
|
struct vnode *lowervp;
|
|
{
|
|
struct thread *td = curthread; /* XXX */
|
|
struct null_node_hashhead *hd;
|
|
struct null_node *a;
|
|
struct vnode *vp;
|
|
|
|
/*
|
|
* Find hash base, and then search the (two-way) linked
|
|
* list looking for a null_node structure which is referencing
|
|
* the lower vnode. If found, the increment the null_node
|
|
* reference count (but NOT the lower vnode's VREF counter).
|
|
*/
|
|
hd = NULL_NHASH(lowervp);
|
|
loop:
|
|
mtx_lock(&null_hashmtx);
|
|
LIST_FOREACH(a, hd, null_hash) {
|
|
if (a->null_lowervp == lowervp) {
|
|
vp = NULLTOV(a);
|
|
mtx_lock(&vp->v_interlock);
|
|
mtx_unlock(&null_hashmtx);
|
|
/*
|
|
* We need vget for the VXLOCK
|
|
* stuff, but we don't want to lock
|
|
* the lower node.
|
|
*/
|
|
if (vget(vp, LK_EXCLUSIVE | LK_THISLAYER | LK_INTERLOCK, td))
|
|
goto loop;
|
|
|
|
return (vp);
|
|
}
|
|
}
|
|
mtx_unlock(&null_hashmtx);
|
|
return (NULLVP);
|
|
}
|
|
|
|
/*
|
|
* Act like null_hashget, but add passed null_node to hash if no existing
|
|
* node found.
|
|
*/
|
|
static struct vnode *
|
|
null_hashins(xp)
|
|
struct null_node *xp;
|
|
{
|
|
struct thread *td = curthread; /* XXX */
|
|
struct null_node_hashhead *hd;
|
|
struct null_node *oxp;
|
|
struct vnode *ovp;
|
|
|
|
hd = NULL_NHASH(xp->null_lowervp);
|
|
loop:
|
|
mtx_lock(&null_hashmtx);
|
|
LIST_FOREACH(oxp, hd, null_hash) {
|
|
if (oxp->null_lowervp == xp->null_lowervp) {
|
|
ovp = NULLTOV(oxp);
|
|
mtx_lock(&ovp->v_interlock);
|
|
mtx_unlock(&null_hashmtx);
|
|
if (vget(ovp, LK_EXCLUSIVE | LK_THISLAYER | LK_INTERLOCK, td))
|
|
goto loop;
|
|
|
|
return (ovp);
|
|
}
|
|
}
|
|
LIST_INSERT_HEAD(hd, xp, null_hash);
|
|
mtx_unlock(&null_hashmtx);
|
|
return (NULLVP);
|
|
}
|
|
|
|
/*
|
|
* Make a new or get existing nullfs node.
|
|
* Vp is the alias vnode, lowervp is the lower vnode.
|
|
*
|
|
* The lowervp assumed to be locked and having "spare" reference. This routine
|
|
* vrele lowervp if nullfs node was taken from hash. Otherwise it "transfers"
|
|
* the caller's "spare" reference to created nullfs vnode.
|
|
*/
|
|
int
|
|
null_nodeget(mp, lowervp, vpp)
|
|
struct mount *mp;
|
|
struct vnode *lowervp;
|
|
struct vnode **vpp;
|
|
{
|
|
struct thread *td = curthread; /* XXX */
|
|
struct null_node *xp;
|
|
struct vnode *vp;
|
|
int error;
|
|
|
|
/* Lookup the hash firstly */
|
|
*vpp = null_hashget(lowervp);
|
|
if (*vpp != NULL) {
|
|
vrele(lowervp);
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* We do not serialize vnode creation, instead we will check for
|
|
* duplicates later, when adding new vnode to hash.
|
|
*
|
|
* Note that duplicate can only appear in hash if the lowervp is
|
|
* locked LK_SHARED.
|
|
*/
|
|
|
|
/*
|
|
* Do the MALLOC before the getnewvnode since doing so afterward
|
|
* might cause a bogus v_data pointer to get dereferenced
|
|
* elsewhere if MALLOC should block.
|
|
*/
|
|
MALLOC(xp, struct null_node *, sizeof(struct null_node),
|
|
M_NULLFSNODE, M_WAITOK);
|
|
|
|
error = getnewvnode("null", mp, null_vnodeop_p, &vp);
|
|
if (error) {
|
|
FREE(xp, M_NULLFSNODE);
|
|
return (error);
|
|
}
|
|
|
|
xp->null_vnode = vp;
|
|
xp->null_lowervp = lowervp;
|
|
|
|
vp->v_type = lowervp->v_type;
|
|
vp->v_data = xp;
|
|
|
|
/*
|
|
* From NetBSD:
|
|
* Now lock the new node. We rely on the fact that we were passed
|
|
* a locked vnode. If the lower node is exporting a struct lock
|
|
* (v_vnlock != NULL) then we just set the upper v_vnlock to the
|
|
* lower one, and both are now locked. If the lower node is exporting
|
|
* NULL, then we copy that up and manually lock the new vnode.
|
|
*/
|
|
|
|
vp->v_vnlock = lowervp->v_vnlock;
|
|
error = VOP_LOCK(vp, LK_EXCLUSIVE | LK_THISLAYER, td);
|
|
if (error)
|
|
panic("null_nodeget: can't lock new vnode\n");
|
|
|
|
/*
|
|
* Atomically insert our new node into the hash or vget existing
|
|
* if someone else has beaten us to it.
|
|
*/
|
|
*vpp = null_hashins(xp);
|
|
if (*vpp != NULL) {
|
|
vrele(lowervp);
|
|
VOP_UNLOCK(vp, LK_THISLAYER, td);
|
|
vp->v_vnlock = NULL;
|
|
xp->null_lowervp = NULL;
|
|
vrele(vp);
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* XXX We take extra vref just to workaround UFS's XXX:
|
|
* UFS can vrele() vnode in VOP_CLOSE() in some cases. Luckily, this
|
|
* can only happen if v_usecount == 1. To workaround, we just don't
|
|
* let v_usecount be 1, it will be 2 or more.
|
|
*/
|
|
VREF(lowervp);
|
|
|
|
*vpp = vp;
|
|
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Remove node from hash.
|
|
*/
|
|
void
|
|
null_hashrem(xp)
|
|
struct null_node *xp;
|
|
{
|
|
|
|
mtx_lock(&null_hashmtx);
|
|
LIST_REMOVE(xp, null_hash);
|
|
mtx_unlock(&null_hashmtx);
|
|
}
|
|
|
|
#ifdef DIAGNOSTIC
|
|
#include "opt_ddb.h"
|
|
|
|
#ifdef DDB
|
|
#define null_checkvp_barrier 1
|
|
#else
|
|
#define null_checkvp_barrier 0
|
|
#endif
|
|
|
|
struct vnode *
|
|
null_checkvp(vp, fil, lno)
|
|
struct vnode *vp;
|
|
char *fil;
|
|
int lno;
|
|
{
|
|
struct null_node *a = VTONULL(vp);
|
|
#ifdef notyet
|
|
/*
|
|
* Can't do this check because vop_reclaim runs
|
|
* with a funny vop vector.
|
|
*/
|
|
if (vp->v_op != null_vnodeop_p) {
|
|
printf ("null_checkvp: on non-null-node\n");
|
|
while (null_checkvp_barrier) /*WAIT*/ ;
|
|
panic("null_checkvp");
|
|
};
|
|
#endif
|
|
if (a->null_lowervp == NULLVP) {
|
|
/* Should never happen */
|
|
int i; u_long *p;
|
|
printf("vp = %p, ZERO ptr\n", (void *)vp);
|
|
for (p = (u_long *) a, i = 0; i < 8; i++)
|
|
printf(" %lx", p[i]);
|
|
printf("\n");
|
|
/* wait for debugger */
|
|
while (null_checkvp_barrier) /*WAIT*/ ;
|
|
panic("null_checkvp");
|
|
}
|
|
if (vrefcnt(a->null_lowervp) < 1) {
|
|
int i; u_long *p;
|
|
printf("vp = %p, unref'ed lowervp\n", (void *)vp);
|
|
for (p = (u_long *) a, i = 0; i < 8; i++)
|
|
printf(" %lx", p[i]);
|
|
printf("\n");
|
|
/* wait for debugger */
|
|
while (null_checkvp_barrier) /*WAIT*/ ;
|
|
panic ("null with unref'ed lowervp");
|
|
};
|
|
#ifdef notyet
|
|
printf("null %x/%d -> %x/%d [%s, %d]\n",
|
|
NULLTOV(a), vrefcnt(NULLTOV(a)),
|
|
a->null_lowervp, vrefcnt(a->null_lowervp),
|
|
fil, lno);
|
|
#endif
|
|
return a->null_lowervp;
|
|
}
|
|
#endif
|