freebsd-nq/sys/fs/umapfs/umap_subr.c
Tor Egge 61b9d89ff0 Make insmntque() externally visibile and allow it to fail (e.g. during
late stages of unmount).  On failure, the vnode is recycled.

Add insmntque1(), to allow for file system specific cleanup when
recycling vnode on failure.

Change getnewvnode() to no longer call insmntque().  Previously,
embryonic vnodes were put onto the list of vnode belonging to a file
system, which is unsafe for a file system marked MPSAFE.

Change vfs_hash_insert() to no longer lock the vnode.  The caller now
has that responsibility.

Change most file systems to lock the vnode and call insmntque() or
insmntque1() after a new vnode has been sufficiently setup.  Handle
failed insmntque*() calls by propagating errors to callers, possibly
after some file system specific cleanup.

Approved by:	re (kensmith)
Reviewed by:	kib
In collaboration with:	kib
2007-03-13 01:50:27 +00:00

410 lines
9.6 KiB
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
*
* $FreeBSD$
*/
#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;
error = insmntque(vp, mp); /* XXX: Too early for mpsafe fs */
if (error != 0) {
FREE(xp, M_TEMP);
*vpp = NULLVP;
return (error);
}
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;
}
}