FreeBSD-5.3/sys/fs/umapfs/umap_subr.c
/*
* Copyright (c) 1992, 1993, 1995
* 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.
* 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.
*
* @(#)umap_subr.c 8.9 (Berkeley) 5/14/95
*
* $FreeBSD: src/sys/fs/umapfs/umap_subr.c,v 1.33 2004/04/07 20:46:02 imp Exp $
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mount.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <fs/umapfs/umap.h>
#define LOG2_SIZEVNODE 7 /* log2(sizeof struct vnode) */
#define NUMAPNODECACHE 16
/*
* Null layer cache:
* Each cache entry holds a reference to the target vnode
* along with a pointer to the alias vnode. When an
* entry is added the target vnode is VREF'd. When the
* alias is removed the target vnode is vrele'd.
*/
#define UMAP_NHASH(vp) \
(&umap_node_hashtbl \
[((uintptr_t)(void *)(vp) >> LOG2_SIZEVNODE) & umap_node_hash])
static LIST_HEAD(umap_node_hashhead, umap_node) *umap_node_hashtbl;
static u_long umap_node_hash;
static u_long umap_findid(u_long id, u_long map[][2], int nentries);
static int umap_node_alloc(struct mount *mp, struct vnode *lowervp,
struct vnode **vpp);
static struct vnode *
umap_node_find(struct mount *mp, struct vnode *targetvp);
/*
* Initialise cache headers
*/
int
umapfs_init(vfsp)
struct vfsconf *vfsp;
{
#ifdef DEBUG
printf("umapfs_init\n"); /* printed during system boot */
#endif
umap_node_hashtbl = hashinit(NUMAPNODECACHE, M_CACHE, &umap_node_hash);
return (0);
}
/*
* umap_findid is called by various routines in umap_vnodeops.c to
* find a user or group id in a map.
*/
static u_long
umap_findid(id, map, nentries)
u_long id;
u_long map[][2];
int nentries;
{
int i;
/* Find uid entry in map */
i = 0;
while ((i<nentries) && ((map[i][0]) != id))
i++;
if (i < nentries)
return (map[i][1]);
else
return (-1);
}
/*
* umap_reverse_findid is called by umap_getattr() in umap_vnodeops.c to
* find a user or group id in a map, in reverse.
*/
u_long
umap_reverse_findid(id, map, nentries)
u_long id;
u_long map[][2];
int nentries;
{
int i;
/* Find uid entry in map */
i = 0;
while ((i<nentries) && ((map[i][1]) != id))
i++;
if (i < nentries)
return (map[i][0]);
else
return (-1);
}
/*
* Return alias for target vnode if already exists, else 0.
*/
static struct vnode *
umap_node_find(mp, targetvp)
struct mount *mp;
struct vnode *targetvp;
{
struct thread *td = curthread; /* XXX */
struct umap_node_hashhead *hd;
struct umap_node *a;
struct vnode *vp;
#ifdef DEBUG
printf("umap_node_find(mp = %p, target = %p)\n",
(void *)mp, (void *)targetvp);
#endif
/*
* Find hash base, and then search the (two-way) linked
* list looking for a umap_node structure which is referencing
* the target vnode. If found, the increment the umap_node
* reference count (but NOT the target vnode's VREF counter).
*/
hd = UMAP_NHASH(targetvp);
loop:
LIST_FOREACH(a, hd, umap_hash) {
if (a->umap_lowervp == targetvp &&
a->umap_vnode->v_mount == mp) {
vp = UMAPTOV(a);
/*
* We need vget for the VXLOCK
* stuff, but we don't want to lock
* the lower node.
*/
if (vget(vp, 0, td)) {
#ifdef DEBUG
printf ("umap_node_find: vget failed.\n");
#endif
goto loop;
}
return (vp);
}
}
#ifdef DEBUG
printf("umap_node_find(%p, %p): NOT found\n",
(void *)mp, (void *)targetvp);
#endif
return (0);
}
/*
* Make a new umap_node node.
* Vp is the alias vnode, lofsvp is the target vnode.
* Maintain a reference to (targetvp).
*/
static int
umap_node_alloc(mp, lowervp, vpp)
struct mount *mp;
struct vnode *lowervp;
struct vnode **vpp;
{
struct umap_node_hashhead *hd;
struct umap_node *xp;
struct vnode *othervp, *vp;
int error;
/* XXX This routine probably needs a node_alloc lock */
/*
* 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 umap_node *, sizeof(struct umap_node),
M_TEMP, M_WAITOK);
error = getnewvnode("umap", mp, umap_vnodeop_p, vpp);
if (error) {
FREE(xp, M_TEMP);
return (error);
}
vp = *vpp;
vp->v_type = lowervp->v_type;
xp->umap_vnode = vp;
vp->v_data = xp;
xp->umap_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.)
*/
othervp = umap_node_find(mp, lowervp);
if (othervp) {
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 umap_node_create */
hd = UMAP_NHASH(lowervp);
LIST_INSERT_HEAD(hd, xp, umap_hash);
return (0);
}
/*
* Try to find an existing umap_node vnode refering
* to it, otherwise make a new umap_node vnode which
* contains a reference to the target vnode.
*/
int
umap_node_create(mp, targetvp, newvpp)
struct mount *mp;
struct vnode *targetvp;
struct vnode **newvpp;
{
struct vnode *aliasvp;
aliasvp = umap_node_find(mp, targetvp);
if (aliasvp) {
/*
* Take another reference to the alias vnode
*/
#ifdef DEBUG
vprint("umap_node_create: exists", aliasvp);
#endif
/* VREF(aliasvp); */
} else {
int error;
/*
* Get new vnode.
*/
#ifdef DEBUG
printf("umap_node_create: create new alias vnode\n");
#endif
/*
* Make new vnode reference the umap_node.
*/
error = umap_node_alloc(mp, targetvp, &aliasvp);
if (error)
return (error);
/*
* aliasvp is already VREF'd by getnewvnode()
*/
}
vrele(targetvp);
#ifdef DEBUG
vprint("umap_node_create: alias", aliasvp);
vprint("umap_node_create: target", targetvp);
#endif
*newvpp = aliasvp;
return (0);
}
#ifdef DIAGNOSTIC
int umap_checkvp_barrier = 1;
struct vnode *
umap_checkvp(vp, fil, lno)
struct vnode *vp;
char *fil;
int lno;
{
struct umap_node *a = VTOUMAP(vp);
#if 0
/*
* Can't do this check because vop_reclaim runs
* with funny vop vector.
*/
if (vp->v_op != umap_vnodeop_p) {
printf ("umap_checkvp: on non-umap-node\n");
while (umap_checkvp_barrier) /*WAIT*/ ;
panic("umap_checkvp");
}
#endif
if (a->umap_lowervp == NULL) {
/* 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(" %p", (void *)p[i]);
printf("\n");
/* wait for debugger */
while (umap_checkvp_barrier) /*WAIT*/ ;
panic("umap_checkvp");
}
if (vrefcnt(a->umap_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(" %p", (void *)p[i]);
printf("\n");
/* wait for debugger */
while (umap_checkvp_barrier) /*WAIT*/ ;
panic ("umap with unref'ed lowervp");
}
#if 0
printf("umap %x/%d -> %x/%d [%s, %d]\n",
a->umap_vnode, a->umap_vnode->v_usecount,
a->umap_lowervp, a->umap_lowervp->v_usecount,
fil, lno);
#endif
return (a->umap_lowervp);
}
#endif /* DIAGNOSTIC */
/* umap_mapids maps all of the ids in a credential, both user and group. */
void
umap_mapids(v_mount, credp)
struct mount *v_mount;
struct ucred *credp;
{
int i;
uid_t uid;
gid_t gid;
if (credp == NOCRED)
return;
KASSERT(!crshared(credp), ("remapping a shared cred"));
/* Find uid entry in map */
uid = (uid_t) umap_findid(credp->cr_uid,
MOUNTTOUMAPMOUNT(v_mount)->info_mapdata,
MOUNTTOUMAPMOUNT(v_mount)->info_nentries);
if (uid != -1)
credp->cr_uid = uid;
else
credp->cr_uid = (uid_t) NOBODY;
#ifdef notdef
/* cr_gid is the same as cr_groups[0] in 4BSD */
/* Find gid entry in map */
gid = (gid_t) umap_findid(credp->cr_gid,
MOUNTTOUMAPMOUNT(v_mount)->info_gmapdata,
MOUNTTOUMAPMOUNT(v_mount)->info_gnentries);
if (gid != -1)
credp->cr_gid = gid;
else
credp->cr_gid = NULLGROUP;
#endif
/* Now we must map each of the set of groups in the cr_groups
structure. */
i = 0;
while (credp->cr_groups[i] != 0) {
gid = (gid_t) umap_findid(credp->cr_groups[i],
MOUNTTOUMAPMOUNT(v_mount)->info_gmapdata,
MOUNTTOUMAPMOUNT(v_mount)->info_gnentries);
if (gid != -1)
credp->cr_groups[i++] = gid;
else
credp->cr_groups[i++] = NULLGROUP;
}
}