#include <machine/rtems-bsd-kernel-space.h>
/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 2001 Dag-Erling Coïdan Smørgrav
* All rights reserved.
*
* 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
* in this position and unchanged.
* 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. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <rtems/bsd/local/opt_pseudofs.h>
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/eventhandler.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/sysctl.h>
#include <sys/vnode.h>
#include <fs/pseudofs/pseudofs.h>
#include <fs/pseudofs/pseudofs_internal.h>
static MALLOC_DEFINE(M_PFSVNCACHE, "pfs_vncache", "pseudofs vnode cache");
static struct mtx pfs_vncache_mutex;
static struct pfs_vdata *pfs_vncache;
static eventhandler_tag pfs_exit_tag;
static void pfs_exit(void *arg, struct proc *p);
static void pfs_purge_locked(struct pfs_node *pn, bool force);
static SYSCTL_NODE(_vfs_pfs, OID_AUTO, vncache, CTLFLAG_RW, 0,
"pseudofs vnode cache");
static int pfs_vncache_entries;
SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, entries, CTLFLAG_RD,
&pfs_vncache_entries, 0,
"number of entries in the vnode cache");
static int pfs_vncache_maxentries;
SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, maxentries, CTLFLAG_RD,
&pfs_vncache_maxentries, 0,
"highest number of entries in the vnode cache");
static int pfs_vncache_hits;
SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, hits, CTLFLAG_RD,
&pfs_vncache_hits, 0,
"number of cache hits since initialization");
static int pfs_vncache_misses;
SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, misses, CTLFLAG_RD,
&pfs_vncache_misses, 0,
"number of cache misses since initialization");
extern struct vop_vector pfs_vnodeops; /* XXX -> .h file */
/*
* Initialize vnode cache
*/
void
pfs_vncache_load(void)
{
mtx_init(&pfs_vncache_mutex, "pfs_vncache", NULL, MTX_DEF);
pfs_exit_tag = EVENTHANDLER_REGISTER(process_exit, pfs_exit, NULL,
EVENTHANDLER_PRI_ANY);
}
/*
* Tear down vnode cache
*/
void
pfs_vncache_unload(void)
{
EVENTHANDLER_DEREGISTER(process_exit, pfs_exit_tag);
mtx_lock(&pfs_vncache_mutex);
pfs_purge_locked(NULL, true);
mtx_unlock(&pfs_vncache_mutex);
KASSERT(pfs_vncache_entries == 0,
("%d vncache entries remaining", pfs_vncache_entries));
mtx_destroy(&pfs_vncache_mutex);
}
/*
* Allocate a vnode
*/
int
pfs_vncache_alloc(struct mount *mp, struct vnode **vpp,
struct pfs_node *pn, pid_t pid)
{
struct pfs_vdata *pvd, *pvd2;
struct vnode *vp;
int error;
/*
* See if the vnode is in the cache.
* XXX linear search is not very efficient.
*/
retry:
mtx_lock(&pfs_vncache_mutex);
for (pvd = pfs_vncache; pvd; pvd = pvd->pvd_next) {
if (pvd->pvd_pn == pn && pvd->pvd_pid == pid &&
pvd->pvd_vnode->v_mount == mp) {
vp = pvd->pvd_vnode;
VI_LOCK(vp);
mtx_unlock(&pfs_vncache_mutex);
if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK, curthread) == 0) {
++pfs_vncache_hits;
*vpp = vp;
/*
* Some callers cache_enter(vp) later, so
* we have to make sure it's not in the
* VFS cache so it doesn't get entered
* twice. A better solution would be to
* make pfs_vncache_alloc() responsible
* for entering the vnode in the VFS
* cache.
*/
cache_purge(vp);
return (0);
}
goto retry;
}
}
mtx_unlock(&pfs_vncache_mutex);
/* nope, get a new one */
pvd = malloc(sizeof *pvd, M_PFSVNCACHE, M_WAITOK);
pvd->pvd_next = pvd->pvd_prev = NULL;
error = getnewvnode("pseudofs", mp, &pfs_vnodeops, vpp);
if (error) {
free(pvd, M_PFSVNCACHE);
return (error);
}
pvd->pvd_pn = pn;
pvd->pvd_pid = pid;
(*vpp)->v_data = pvd;
switch (pn->pn_type) {
case pfstype_root:
(*vpp)->v_vflag = VV_ROOT;
#if 0
printf("root vnode allocated\n");
#endif
/* fall through */
case pfstype_dir:
case pfstype_this:
case pfstype_parent:
case pfstype_procdir:
(*vpp)->v_type = VDIR;
break;
case pfstype_file:
(*vpp)->v_type = VREG;
break;
case pfstype_symlink:
(*vpp)->v_type = VLNK;
break;
case pfstype_none:
KASSERT(0, ("pfs_vncache_alloc called for null node\n"));
default:
panic("%s has unexpected type: %d", pn->pn_name, pn->pn_type);
}
/*
* Propagate flag through to vnode so users know it can change
* if the process changes (i.e. execve)
*/
if ((pn->pn_flags & PFS_PROCDEP) != 0)
(*vpp)->v_vflag |= VV_PROCDEP;
pvd->pvd_vnode = *vpp;
vn_lock(*vpp, LK_EXCLUSIVE | LK_RETRY);
VN_LOCK_AREC(*vpp);
error = insmntque(*vpp, mp);
if (error != 0) {
free(pvd, M_PFSVNCACHE);
*vpp = NULLVP;
return (error);
}
retry2:
mtx_lock(&pfs_vncache_mutex);
/*
* Other thread may race with us, creating the entry we are
* going to insert into the cache. Recheck after
* pfs_vncache_mutex is reacquired.
*/
for (pvd2 = pfs_vncache; pvd2; pvd2 = pvd2->pvd_next) {
if (pvd2->pvd_pn == pn && pvd2->pvd_pid == pid &&
pvd2->pvd_vnode->v_mount == mp) {
vp = pvd2->pvd_vnode;
VI_LOCK(vp);
mtx_unlock(&pfs_vncache_mutex);
if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK, curthread) == 0) {
++pfs_vncache_hits;
vgone(*vpp);
vput(*vpp);
*vpp = vp;
cache_purge(vp);
return (0);
}
goto retry2;
}
}
++pfs_vncache_misses;
if (++pfs_vncache_entries > pfs_vncache_maxentries)
pfs_vncache_maxentries = pfs_vncache_entries;
pvd->pvd_prev = NULL;
pvd->pvd_next = pfs_vncache;
if (pvd->pvd_next)
pvd->pvd_next->pvd_prev = pvd;
pfs_vncache = pvd;
mtx_unlock(&pfs_vncache_mutex);
return (0);
}
/*
* Free a vnode
*/
int
pfs_vncache_free(struct vnode *vp)
{
struct pfs_vdata *pvd;
mtx_lock(&pfs_vncache_mutex);
pvd = (struct pfs_vdata *)vp->v_data;
KASSERT(pvd != NULL, ("pfs_vncache_free(): no vnode data\n"));
if (pvd->pvd_next)
pvd->pvd_next->pvd_prev = pvd->pvd_prev;
if (pvd->pvd_prev) {
pvd->pvd_prev->pvd_next = pvd->pvd_next;
--pfs_vncache_entries;
} else if (pfs_vncache == pvd) {
pfs_vncache = pvd->pvd_next;
--pfs_vncache_entries;
}
mtx_unlock(&pfs_vncache_mutex);
free(pvd, M_PFSVNCACHE);
vp->v_data = NULL;
return (0);
}
/*
* Purge the cache of dead entries
*
* This is extremely inefficient due to the fact that vgone() not only
* indirectly modifies the vnode cache, but may also sleep. We can
* neither hold pfs_vncache_mutex across a vgone() call, nor make any
* assumptions about the state of the cache after vgone() returns. In
* consequence, we must start over after every vgone() call, and keep
* trying until we manage to traverse the entire cache.
*
* The only way to improve this situation is to change the data structure
* used to implement the cache.
*/
static void
pfs_purge_locked(struct pfs_node *pn, bool force)
{
struct pfs_vdata *pvd;
struct vnode *vnp;
mtx_assert(&pfs_vncache_mutex, MA_OWNED);
pvd = pfs_vncache;
while (pvd != NULL) {
if (force || pvd->pvd_dead ||
(pn != NULL && pvd->pvd_pn == pn)) {
vnp = pvd->pvd_vnode;
vhold(vnp);
mtx_unlock(&pfs_vncache_mutex);
VOP_LOCK(vnp, LK_EXCLUSIVE);
vgone(vnp);
VOP_UNLOCK(vnp, 0);
mtx_lock(&pfs_vncache_mutex);
vdrop(vnp);
pvd = pfs_vncache;
} else {
pvd = pvd->pvd_next;
}
}
}
void
pfs_purge(struct pfs_node *pn)
{
mtx_lock(&pfs_vncache_mutex);
pfs_purge_locked(pn, false);
mtx_unlock(&pfs_vncache_mutex);
}
/*
* Free all vnodes associated with a defunct process
*/
static void
pfs_exit(void *arg, struct proc *p)
{
struct pfs_vdata *pvd;
int dead;
if (pfs_vncache == NULL)
return;
mtx_lock(&pfs_vncache_mutex);
for (pvd = pfs_vncache, dead = 0; pvd != NULL; pvd = pvd->pvd_next)
if (pvd->pvd_pid == p->p_pid)
dead = pvd->pvd_dead = 1;
if (dead)
pfs_purge_locked(NULL, false);
mtx_unlock(&pfs_vncache_mutex);
}
