296 lines
7.7 KiB
C
296 lines
7.7 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 8.4 (Berkeley) 1/21/94
|
|
*
|
|
* $Id: lofs_subr.c,v 1.11 1992/05/30 10:05:43 jsp Exp jsp $
|
|
*/
|
|
|
|
#include <sys/param.h>
|
|
#include <sys/systm.h>
|
|
#include <sys/time.h>
|
|
#include <sys/types.h>
|
|
#include <sys/vnode.h>
|
|
#include <sys/mount.h>
|
|
#include <sys/namei.h>
|
|
#include <sys/malloc.h>
|
|
#include <miscfs/nullfs/null.h>
|
|
|
|
#define LOG2_SIZEVNODE 7 /* log2(sizeof struct vnode) */
|
|
#define NNULLNODECACHE 16
|
|
#define NULL_NHASH(vp) ((((u_long)vp)>>LOG2_SIZEVNODE) & (NNULLNODECACHE-1))
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
|
|
/*
|
|
* Cache head
|
|
*/
|
|
struct null_node_cache {
|
|
struct null_node *ac_forw;
|
|
struct null_node *ac_back;
|
|
};
|
|
|
|
static struct null_node_cache null_node_cache[NNULLNODECACHE];
|
|
|
|
/*
|
|
* Initialise cache headers
|
|
*/
|
|
int
|
|
nullfs_init()
|
|
{
|
|
struct null_node_cache *ac;
|
|
#ifdef NULLFS_DIAGNOSTIC
|
|
printf("nullfs_init\n"); /* printed during system boot */
|
|
#endif
|
|
|
|
for (ac = null_node_cache; ac < null_node_cache + NNULLNODECACHE; ac++)
|
|
ac->ac_forw = ac->ac_back = (struct null_node *) ac;
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Compute hash list for given lower vnode
|
|
*/
|
|
static struct null_node_cache *
|
|
null_node_hash(lowervp)
|
|
struct vnode *lowervp;
|
|
{
|
|
|
|
return (&null_node_cache[NULL_NHASH(lowervp)]);
|
|
}
|
|
|
|
/*
|
|
* Return a VREF'ed alias for lower vnode if already exists, else 0.
|
|
*/
|
|
static struct vnode *
|
|
null_node_find(mp, lowervp)
|
|
struct mount *mp;
|
|
struct vnode *lowervp;
|
|
{
|
|
struct null_node_cache *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_node_hash(lowervp);
|
|
loop:
|
|
for (a = hd->ac_forw; a != (struct null_node *) hd; a = a->null_forw) {
|
|
if (a->null_lowervp == lowervp && NULLTOV(a)->v_mount == mp) {
|
|
vp = NULLTOV(a);
|
|
/*
|
|
* We need vget for the VXLOCK
|
|
* stuff, but we don't want to lock
|
|
* the lower node.
|
|
*/
|
|
if (vget(vp, 0)) {
|
|
printf ("null_node_find: vget failed.\n");
|
|
goto loop;
|
|
};
|
|
return (vp);
|
|
}
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
|
|
/*
|
|
* Make a new null_node node.
|
|
* Vp is the alias vnode, lofsvp is the lower vnode.
|
|
* Maintain a reference to (lowervp).
|
|
*/
|
|
static int
|
|
null_node_alloc(mp, lowervp, vpp)
|
|
struct mount *mp;
|
|
struct vnode *lowervp;
|
|
struct vnode **vpp;
|
|
{
|
|
struct null_node_cache *hd;
|
|
struct null_node *xp;
|
|
struct vnode *othervp, *vp;
|
|
int error;
|
|
|
|
if (error = getnewvnode(VT_NULL, mp, null_vnodeop_p, vpp))
|
|
return (error);
|
|
vp = *vpp;
|
|
|
|
MALLOC(xp, struct null_node *, sizeof(struct null_node), M_TEMP, M_WAITOK);
|
|
vp->v_type = lowervp->v_type;
|
|
xp->null_vnode = vp;
|
|
vp->v_data = xp;
|
|
xp->null_lowervp = lowervp;
|
|
/*
|
|
* Before we insert our new node onto the hash chains,
|
|
* check to see if someone else has beaten us to it.
|
|
* (We could have slept in MALLOC.)
|
|
*/
|
|
if (othervp = null_node_find(lowervp)) {
|
|
FREE(xp, M_TEMP);
|
|
vp->v_type = VBAD; /* node is discarded */
|
|
vp->v_usecount = 0; /* XXX */
|
|
*vpp = othervp;
|
|
return 0;
|
|
};
|
|
VREF(lowervp); /* Extra VREF will be vrele'd in null_node_create */
|
|
hd = null_node_hash(lowervp);
|
|
insque(xp, hd);
|
|
return 0;
|
|
}
|
|
|
|
|
|
/*
|
|
* Try to find an existing null_node vnode refering
|
|
* to it, otherwise make a new null_node vnode which
|
|
* contains a reference to the lower vnode.
|
|
*/
|
|
int
|
|
null_node_create(mp, lowervp, newvpp)
|
|
struct mount *mp;
|
|
struct vnode *lowervp;
|
|
struct vnode **newvpp;
|
|
{
|
|
struct vnode *aliasvp;
|
|
|
|
if (aliasvp = null_node_find(mp, lowervp)) {
|
|
/*
|
|
* null_node_find has taken another reference
|
|
* to the alias vnode.
|
|
*/
|
|
#ifdef NULLFS_DIAGNOSTIC
|
|
vprint("null_node_create: exists", NULLTOV(ap));
|
|
#endif
|
|
/* VREF(aliasvp); --- done in null_node_find */
|
|
} else {
|
|
int error;
|
|
|
|
/*
|
|
* Get new vnode.
|
|
*/
|
|
#ifdef NULLFS_DIAGNOSTIC
|
|
printf("null_node_create: create new alias vnode\n");
|
|
#endif
|
|
|
|
/*
|
|
* Make new vnode reference the null_node.
|
|
*/
|
|
if (error = null_node_alloc(mp, lowervp, &aliasvp))
|
|
return error;
|
|
|
|
/*
|
|
* aliasvp is already VREF'd by getnewvnode()
|
|
*/
|
|
}
|
|
|
|
vrele(lowervp);
|
|
|
|
#ifdef DIAGNOSTIC
|
|
if (lowervp->v_usecount < 1) {
|
|
/* Should never happen... */
|
|
vprint ("null_node_create: alias ");
|
|
vprint ("null_node_create: lower ");
|
|
printf ("null_node_create: lower has 0 usecount.\n");
|
|
panic ("null_node_create: lower has 0 usecount.");
|
|
};
|
|
#endif
|
|
|
|
#ifdef NULLFS_DIAGNOSTIC
|
|
vprint("null_node_create: alias", aliasvp);
|
|
vprint("null_node_create: lower", lowervp);
|
|
#endif
|
|
|
|
*newvpp = aliasvp;
|
|
return (0);
|
|
}
|
|
#ifdef NULLFS_DIAGNOSTIC
|
|
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 == NULL) {
|
|
/* Should never happen */
|
|
int i; u_long *p;
|
|
printf("vp = %x, ZERO ptr\n", vp);
|
|
for (p = (u_long *) a, i = 0; i < 8; i++)
|
|
printf(" %x", p[i]);
|
|
printf("\n");
|
|
/* wait for debugger */
|
|
while (null_checkvp_barrier) /*WAIT*/ ;
|
|
panic("null_checkvp");
|
|
}
|
|
if (a->null_lowervp->v_usecount < 1) {
|
|
int i; u_long *p;
|
|
printf("vp = %x, unref'ed lowervp\n", vp);
|
|
for (p = (u_long *) a, i = 0; i < 8; i++)
|
|
printf(" %x", 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), NULLTOV(a)->v_usecount,
|
|
a->null_lowervp, a->null_lowervp->v_usecount,
|
|
fil, lno);
|
|
#endif
|
|
return a->null_lowervp;
|
|
}
|
|
#endif
|