6472ac3d8a
The SYSCTL_NODE macro defines a list that stores all child-elements of that node. If there's no SYSCTL_DECL macro anywhere else, there's no reason why it shouldn't be static.
329 lines
8.7 KiB
C
329 lines
8.7 KiB
C
/*-
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* Copyright (c) 2001 Dag-Erling Coïdan Smørgrav
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer
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* in this position and unchanged.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_pseudofs.h"
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#include <sys/param.h>
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#include <sys/kernel.h>
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#include <sys/systm.h>
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#include <sys/eventhandler.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#include <sys/mutex.h>
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#include <sys/proc.h>
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#include <sys/sysctl.h>
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#include <sys/vnode.h>
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#include <fs/pseudofs/pseudofs.h>
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#include <fs/pseudofs/pseudofs_internal.h>
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static MALLOC_DEFINE(M_PFSVNCACHE, "pfs_vncache", "pseudofs vnode cache");
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static struct mtx pfs_vncache_mutex;
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static struct pfs_vdata *pfs_vncache;
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static eventhandler_tag pfs_exit_tag;
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static void pfs_exit(void *arg, struct proc *p);
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static SYSCTL_NODE(_vfs_pfs, OID_AUTO, vncache, CTLFLAG_RW, 0,
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"pseudofs vnode cache");
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static int pfs_vncache_entries;
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SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, entries, CTLFLAG_RD,
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&pfs_vncache_entries, 0,
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"number of entries in the vnode cache");
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static int pfs_vncache_maxentries;
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SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, maxentries, CTLFLAG_RD,
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&pfs_vncache_maxentries, 0,
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"highest number of entries in the vnode cache");
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static int pfs_vncache_hits;
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SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, hits, CTLFLAG_RD,
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&pfs_vncache_hits, 0,
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"number of cache hits since initialization");
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static int pfs_vncache_misses;
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SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, misses, CTLFLAG_RD,
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&pfs_vncache_misses, 0,
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"number of cache misses since initialization");
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extern struct vop_vector pfs_vnodeops; /* XXX -> .h file */
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/*
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* Initialize vnode cache
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*/
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void
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pfs_vncache_load(void)
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{
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mtx_assert(&Giant, MA_OWNED);
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mtx_init(&pfs_vncache_mutex, "pfs_vncache", NULL, MTX_DEF);
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pfs_exit_tag = EVENTHANDLER_REGISTER(process_exit, pfs_exit, NULL,
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EVENTHANDLER_PRI_ANY);
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}
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/*
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* Tear down vnode cache
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*/
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void
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pfs_vncache_unload(void)
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{
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mtx_assert(&Giant, MA_OWNED);
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EVENTHANDLER_DEREGISTER(process_exit, pfs_exit_tag);
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KASSERT(pfs_vncache_entries == 0,
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("%d vncache entries remaining", pfs_vncache_entries));
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mtx_destroy(&pfs_vncache_mutex);
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}
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/*
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* Allocate a vnode
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*/
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int
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pfs_vncache_alloc(struct mount *mp, struct vnode **vpp,
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struct pfs_node *pn, pid_t pid)
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{
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struct pfs_vdata *pvd, *pvd2;
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struct vnode *vp;
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int error;
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/*
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* See if the vnode is in the cache.
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* XXX linear search is not very efficient.
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*/
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retry:
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mtx_lock(&pfs_vncache_mutex);
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for (pvd = pfs_vncache; pvd; pvd = pvd->pvd_next) {
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if (pvd->pvd_pn == pn && pvd->pvd_pid == pid &&
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pvd->pvd_vnode->v_mount == mp) {
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vp = pvd->pvd_vnode;
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VI_LOCK(vp);
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mtx_unlock(&pfs_vncache_mutex);
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if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK, curthread) == 0) {
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++pfs_vncache_hits;
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*vpp = vp;
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/*
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* Some callers cache_enter(vp) later, so
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* we have to make sure it's not in the
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* VFS cache so it doesn't get entered
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* twice. A better solution would be to
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* make pfs_vncache_alloc() responsible
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* for entering the vnode in the VFS
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* cache.
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*/
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cache_purge(vp);
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return (0);
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}
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goto retry;
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}
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}
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mtx_unlock(&pfs_vncache_mutex);
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/* nope, get a new one */
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pvd = malloc(sizeof *pvd, M_PFSVNCACHE, M_WAITOK);
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pvd->pvd_next = pvd->pvd_prev = NULL;
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error = getnewvnode("pseudofs", mp, &pfs_vnodeops, vpp);
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if (error) {
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free(pvd, M_PFSVNCACHE);
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return (error);
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}
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pvd->pvd_pn = pn;
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pvd->pvd_pid = pid;
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(*vpp)->v_data = pvd;
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switch (pn->pn_type) {
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case pfstype_root:
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(*vpp)->v_vflag = VV_ROOT;
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#if 0
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printf("root vnode allocated\n");
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#endif
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/* fall through */
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case pfstype_dir:
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case pfstype_this:
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case pfstype_parent:
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case pfstype_procdir:
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(*vpp)->v_type = VDIR;
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break;
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case pfstype_file:
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(*vpp)->v_type = VREG;
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break;
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case pfstype_symlink:
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(*vpp)->v_type = VLNK;
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break;
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case pfstype_none:
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KASSERT(0, ("pfs_vncache_alloc called for null node\n"));
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default:
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panic("%s has unexpected type: %d", pn->pn_name, pn->pn_type);
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}
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/*
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* Propagate flag through to vnode so users know it can change
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* if the process changes (i.e. execve)
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*/
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if ((pn->pn_flags & PFS_PROCDEP) != 0)
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(*vpp)->v_vflag |= VV_PROCDEP;
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pvd->pvd_vnode = *vpp;
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vn_lock(*vpp, LK_EXCLUSIVE | LK_RETRY);
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VN_LOCK_AREC(*vpp);
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error = insmntque(*vpp, mp);
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if (error != 0) {
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free(pvd, M_PFSVNCACHE);
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*vpp = NULLVP;
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return (error);
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}
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retry2:
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mtx_lock(&pfs_vncache_mutex);
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/*
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* Other thread may race with us, creating the entry we are
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* going to insert into the cache. Recheck after
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* pfs_vncache_mutex is reacquired.
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*/
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for (pvd2 = pfs_vncache; pvd2; pvd2 = pvd2->pvd_next) {
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if (pvd2->pvd_pn == pn && pvd2->pvd_pid == pid &&
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pvd2->pvd_vnode->v_mount == mp) {
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vp = pvd2->pvd_vnode;
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VI_LOCK(vp);
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mtx_unlock(&pfs_vncache_mutex);
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if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK, curthread) == 0) {
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++pfs_vncache_hits;
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vgone(*vpp);
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vput(*vpp);
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*vpp = vp;
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cache_purge(vp);
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return (0);
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}
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goto retry2;
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}
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}
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++pfs_vncache_misses;
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if (++pfs_vncache_entries > pfs_vncache_maxentries)
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pfs_vncache_maxentries = pfs_vncache_entries;
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pvd->pvd_prev = NULL;
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pvd->pvd_next = pfs_vncache;
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if (pvd->pvd_next)
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pvd->pvd_next->pvd_prev = pvd;
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pfs_vncache = pvd;
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mtx_unlock(&pfs_vncache_mutex);
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return (0);
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}
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/*
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* Free a vnode
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*/
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int
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pfs_vncache_free(struct vnode *vp)
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{
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struct pfs_vdata *pvd;
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mtx_lock(&pfs_vncache_mutex);
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pvd = (struct pfs_vdata *)vp->v_data;
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KASSERT(pvd != NULL, ("pfs_vncache_free(): no vnode data\n"));
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if (pvd->pvd_next)
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pvd->pvd_next->pvd_prev = pvd->pvd_prev;
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if (pvd->pvd_prev) {
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pvd->pvd_prev->pvd_next = pvd->pvd_next;
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--pfs_vncache_entries;
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} else if (pfs_vncache == pvd) {
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pfs_vncache = pvd->pvd_next;
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--pfs_vncache_entries;
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}
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mtx_unlock(&pfs_vncache_mutex);
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free(pvd, M_PFSVNCACHE);
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vp->v_data = NULL;
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return (0);
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}
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/*
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* Purge the cache of dead entries
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*
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* This is extremely inefficient due to the fact that vgone() not only
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* indirectly modifies the vnode cache, but may also sleep. We can
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* neither hold pfs_vncache_mutex across a vgone() call, nor make any
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* assumptions about the state of the cache after vgone() returns. In
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* consequence, we must start over after every vgone() call, and keep
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* trying until we manage to traverse the entire cache.
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*
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* The only way to improve this situation is to change the data structure
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* used to implement the cache.
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*/
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static void
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pfs_purge_locked(struct pfs_node *pn)
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{
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struct pfs_vdata *pvd;
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struct vnode *vnp;
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mtx_assert(&pfs_vncache_mutex, MA_OWNED);
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pvd = pfs_vncache;
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while (pvd != NULL) {
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if (pvd->pvd_dead || (pn != NULL && pvd->pvd_pn == pn)) {
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vnp = pvd->pvd_vnode;
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vhold(vnp);
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mtx_unlock(&pfs_vncache_mutex);
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VOP_LOCK(vnp, LK_EXCLUSIVE);
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vgone(vnp);
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VOP_UNLOCK(vnp, 0);
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mtx_lock(&pfs_vncache_mutex);
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vdrop(vnp);
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pvd = pfs_vncache;
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} else {
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pvd = pvd->pvd_next;
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}
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}
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}
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void
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pfs_purge(struct pfs_node *pn)
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{
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mtx_lock(&pfs_vncache_mutex);
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pfs_purge_locked(pn);
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mtx_unlock(&pfs_vncache_mutex);
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}
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/*
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* Free all vnodes associated with a defunct process
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*/
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static void
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pfs_exit(void *arg, struct proc *p)
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{
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struct pfs_vdata *pvd;
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int dead;
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if (pfs_vncache == NULL)
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return;
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mtx_lock(&pfs_vncache_mutex);
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for (pvd = pfs_vncache, dead = 0; pvd != NULL; pvd = pvd->pvd_next)
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if (pvd->pvd_pid == p->p_pid)
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dead = pvd->pvd_dead = 1;
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if (dead)
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pfs_purge_locked(NULL);
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mtx_unlock(&pfs_vncache_mutex);
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}
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