2 * Copyright (c) 2001 Dag-Erling Coïdan Smørgrav
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer
10 * in this position and unchanged.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. The name of the author may not be used to endorse or promote products
15 * derived from this software without specific prior written permission.
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
32 #include "opt_pseudofs.h"
34 #include <sys/param.h>
35 #include <sys/kernel.h>
36 #include <sys/systm.h>
37 #include <sys/eventhandler.h>
39 #include <sys/malloc.h>
40 #include <sys/mutex.h>
42 #include <sys/sysctl.h>
43 #include <sys/vnode.h>
45 #include <fs/pseudofs/pseudofs.h>
46 #include <fs/pseudofs/pseudofs_internal.h>
48 static MALLOC_DEFINE(M_PFSVNCACHE, "pfs_vncache", "pseudofs vnode cache");
50 static struct mtx pfs_vncache_mutex;
51 static struct pfs_vdata *pfs_vncache;
52 static eventhandler_tag pfs_exit_tag;
53 static void pfs_exit(void *arg, struct proc *p);
55 static SYSCTL_NODE(_vfs_pfs, OID_AUTO, vncache, CTLFLAG_RW, 0,
56 "pseudofs vnode cache");
58 static int pfs_vncache_entries;
59 SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, entries, CTLFLAG_RD,
60 &pfs_vncache_entries, 0,
61 "number of entries in the vnode cache");
63 static int pfs_vncache_maxentries;
64 SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, maxentries, CTLFLAG_RD,
65 &pfs_vncache_maxentries, 0,
66 "highest number of entries in the vnode cache");
68 static int pfs_vncache_hits;
69 SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, hits, CTLFLAG_RD,
71 "number of cache hits since initialization");
73 static int pfs_vncache_misses;
74 SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, misses, CTLFLAG_RD,
75 &pfs_vncache_misses, 0,
76 "number of cache misses since initialization");
78 extern struct vop_vector pfs_vnodeops; /* XXX -> .h file */
81 * Initialize vnode cache
84 pfs_vncache_load(void)
87 mtx_assert(&Giant, MA_OWNED);
88 mtx_init(&pfs_vncache_mutex, "pfs_vncache", NULL, MTX_DEF);
89 pfs_exit_tag = EVENTHANDLER_REGISTER(process_exit, pfs_exit, NULL,
90 EVENTHANDLER_PRI_ANY);
94 * Tear down vnode cache
97 pfs_vncache_unload(void)
100 mtx_assert(&Giant, MA_OWNED);
101 EVENTHANDLER_DEREGISTER(process_exit, pfs_exit_tag);
102 KASSERT(pfs_vncache_entries == 0,
103 ("%d vncache entries remaining", pfs_vncache_entries));
104 mtx_destroy(&pfs_vncache_mutex);
111 pfs_vncache_alloc(struct mount *mp, struct vnode **vpp,
112 struct pfs_node *pn, pid_t pid)
114 struct pfs_vdata *pvd, *pvd2;
119 * See if the vnode is in the cache.
120 * XXX linear search is not very efficient.
123 mtx_lock(&pfs_vncache_mutex);
124 for (pvd = pfs_vncache; pvd; pvd = pvd->pvd_next) {
125 if (pvd->pvd_pn == pn && pvd->pvd_pid == pid &&
126 pvd->pvd_vnode->v_mount == mp) {
129 mtx_unlock(&pfs_vncache_mutex);
130 if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK, curthread) == 0) {
134 * Some callers cache_enter(vp) later, so
135 * we have to make sure it's not in the
136 * VFS cache so it doesn't get entered
137 * twice. A better solution would be to
138 * make pfs_vncache_alloc() responsible
139 * for entering the vnode in the VFS
148 mtx_unlock(&pfs_vncache_mutex);
150 /* nope, get a new one */
151 pvd = malloc(sizeof *pvd, M_PFSVNCACHE, M_WAITOK);
152 pvd->pvd_next = pvd->pvd_prev = NULL;
153 error = getnewvnode("pseudofs", mp, &pfs_vnodeops, vpp);
155 free(pvd, M_PFSVNCACHE);
160 (*vpp)->v_data = pvd;
161 switch (pn->pn_type) {
163 (*vpp)->v_vflag = VV_ROOT;
165 printf("root vnode allocated\n");
171 case pfstype_procdir:
172 (*vpp)->v_type = VDIR;
175 (*vpp)->v_type = VREG;
177 case pfstype_symlink:
178 (*vpp)->v_type = VLNK;
181 KASSERT(0, ("pfs_vncache_alloc called for null node\n"));
183 panic("%s has unexpected type: %d", pn->pn_name, pn->pn_type);
186 * Propagate flag through to vnode so users know it can change
187 * if the process changes (i.e. execve)
189 if ((pn->pn_flags & PFS_PROCDEP) != 0)
190 (*vpp)->v_vflag |= VV_PROCDEP;
191 pvd->pvd_vnode = *vpp;
192 vn_lock(*vpp, LK_EXCLUSIVE | LK_RETRY);
194 error = insmntque(*vpp, mp);
196 free(pvd, M_PFSVNCACHE);
201 mtx_lock(&pfs_vncache_mutex);
203 * Other thread may race with us, creating the entry we are
204 * going to insert into the cache. Recheck after
205 * pfs_vncache_mutex is reacquired.
207 for (pvd2 = pfs_vncache; pvd2; pvd2 = pvd2->pvd_next) {
208 if (pvd2->pvd_pn == pn && pvd2->pvd_pid == pid &&
209 pvd2->pvd_vnode->v_mount == mp) {
210 vp = pvd2->pvd_vnode;
212 mtx_unlock(&pfs_vncache_mutex);
213 if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK, curthread) == 0) {
224 ++pfs_vncache_misses;
225 if (++pfs_vncache_entries > pfs_vncache_maxentries)
226 pfs_vncache_maxentries = pfs_vncache_entries;
227 pvd->pvd_prev = NULL;
228 pvd->pvd_next = pfs_vncache;
230 pvd->pvd_next->pvd_prev = pvd;
232 mtx_unlock(&pfs_vncache_mutex);
240 pfs_vncache_free(struct vnode *vp)
242 struct pfs_vdata *pvd;
244 mtx_lock(&pfs_vncache_mutex);
245 pvd = (struct pfs_vdata *)vp->v_data;
246 KASSERT(pvd != NULL, ("pfs_vncache_free(): no vnode data\n"));
248 pvd->pvd_next->pvd_prev = pvd->pvd_prev;
250 pvd->pvd_prev->pvd_next = pvd->pvd_next;
251 --pfs_vncache_entries;
252 } else if (pfs_vncache == pvd) {
253 pfs_vncache = pvd->pvd_next;
254 --pfs_vncache_entries;
256 mtx_unlock(&pfs_vncache_mutex);
258 free(pvd, M_PFSVNCACHE);
264 * Purge the cache of dead entries
266 * This is extremely inefficient due to the fact that vgone() not only
267 * indirectly modifies the vnode cache, but may also sleep. We can
268 * neither hold pfs_vncache_mutex across a vgone() call, nor make any
269 * assumptions about the state of the cache after vgone() returns. In
270 * consequence, we must start over after every vgone() call, and keep
271 * trying until we manage to traverse the entire cache.
273 * The only way to improve this situation is to change the data structure
274 * used to implement the cache.
277 pfs_purge_locked(struct pfs_node *pn)
279 struct pfs_vdata *pvd;
282 mtx_assert(&pfs_vncache_mutex, MA_OWNED);
284 while (pvd != NULL) {
285 if (pvd->pvd_dead || (pn != NULL && pvd->pvd_pn == pn)) {
286 vnp = pvd->pvd_vnode;
288 mtx_unlock(&pfs_vncache_mutex);
289 VOP_LOCK(vnp, LK_EXCLUSIVE);
292 mtx_lock(&pfs_vncache_mutex);
302 pfs_purge(struct pfs_node *pn)
305 mtx_lock(&pfs_vncache_mutex);
306 pfs_purge_locked(pn);
307 mtx_unlock(&pfs_vncache_mutex);
311 * Free all vnodes associated with a defunct process
314 pfs_exit(void *arg, struct proc *p)
316 struct pfs_vdata *pvd;
319 if (pfs_vncache == NULL)
321 mtx_lock(&pfs_vncache_mutex);
322 for (pvd = pfs_vncache, dead = 0; pvd != NULL; pvd = pvd->pvd_next)
323 if (pvd->pvd_pid == p->p_pid)
324 dead = pvd->pvd_dead = 1;
326 pfs_purge_locked(NULL);
327 mtx_unlock(&pfs_vncache_mutex);