1 /*-
2 * Copyright (c) 2001 Dag-Erling Coïdan Smørgrav
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
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.
16 *
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.
27 *
28 * $FreeBSD: releng/5.4/sys/fs/pseudofs/pseudofs_vncache.c 133776 2004-08-15 21:58:02Z des $
29 */
30
31 #include <sys/param.h>
32 #include <sys/kernel.h>
33 #include <sys/systm.h>
34 #include <sys/eventhandler.h>
35 #include <sys/lock.h>
36 #include <sys/malloc.h>
37 #include <sys/mutex.h>
38 #include <sys/proc.h>
39 #include <sys/sysctl.h>
40 #include <sys/vnode.h>
41
42 #include <fs/pseudofs/pseudofs.h>
43 #include <fs/pseudofs/pseudofs_internal.h>
44
45 static MALLOC_DEFINE(M_PFSVNCACHE, "pfs_vncache", "pseudofs vnode cache");
46
47 static struct mtx pfs_vncache_mutex;
48 static struct pfs_vdata *pfs_vncache;
49 static eventhandler_tag pfs_exit_tag;
50 static void pfs_exit(void *arg, struct proc *p);
51
52 SYSCTL_NODE(_vfs_pfs, OID_AUTO, vncache, CTLFLAG_RW, 0,
53 "pseudofs vnode cache");
54
55 static int pfs_vncache_entries;
56 SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, entries, CTLFLAG_RD,
57 &pfs_vncache_entries, 0,
58 "number of entries in the vnode cache");
59
60 static int pfs_vncache_maxentries;
61 SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, maxentries, CTLFLAG_RD,
62 &pfs_vncache_maxentries, 0,
63 "highest number of entries in the vnode cache");
64
65 static int pfs_vncache_hits;
66 SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, hits, CTLFLAG_RD,
67 &pfs_vncache_hits, 0,
68 "number of cache hits since initialization");
69
70 static int pfs_vncache_misses;
71 SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, misses, CTLFLAG_RD,
72 &pfs_vncache_misses, 0,
73 "number of cache misses since initialization");
74
75 extern vop_t **pfs_vnodeop_p;
76
77 /*
78 * Initialize vnode cache
79 */
80 void
81 pfs_vncache_load(void)
82 {
83 mtx_init(&pfs_vncache_mutex, "pseudofs_vncache", NULL, MTX_DEF);
84 pfs_exit_tag = EVENTHANDLER_REGISTER(process_exit, pfs_exit, NULL,
85 EVENTHANDLER_PRI_ANY);
86 }
87
88 /*
89 * Tear down vnode cache
90 */
91 void
92 pfs_vncache_unload(void)
93 {
94 EVENTHANDLER_DEREGISTER(process_exit, pfs_exit_tag);
95 if (pfs_vncache_entries != 0)
96 printf("pfs_vncache_unload(): %d entries remaining\n",
97 pfs_vncache_entries);
98 mtx_destroy(&pfs_vncache_mutex);
99 }
100
101 /*
102 * Allocate a vnode
103 */
104 int
105 pfs_vncache_alloc(struct mount *mp, struct vnode **vpp,
106 struct pfs_node *pn, pid_t pid)
107 {
108 struct pfs_vdata *pvd;
109 int error;
110
111 /*
112 * See if the vnode is in the cache.
113 * XXX linear search is not very efficient.
114 */
115 mtx_lock(&pfs_vncache_mutex);
116 for (pvd = pfs_vncache; pvd; pvd = pvd->pvd_next) {
117 if (pvd->pvd_pn == pn && pvd->pvd_pid == pid &&
118 pvd->pvd_vnode->v_mount == mp) {
119 if (vget(pvd->pvd_vnode, 0, curthread) == 0) {
120 ++pfs_vncache_hits;
121 *vpp = pvd->pvd_vnode;
122 mtx_unlock(&pfs_vncache_mutex);
123 /* XXX see comment at top of pfs_lookup() */
124 cache_purge(*vpp);
125 vn_lock(*vpp, LK_RETRY | LK_EXCLUSIVE,
126 curthread);
127 return (0);
128 }
129 /* XXX if this can happen, we're in trouble */
130 break;
131 }
132 }
133 mtx_unlock(&pfs_vncache_mutex);
134 ++pfs_vncache_misses;
135
136 /* nope, get a new one */
137 MALLOC(pvd, struct pfs_vdata *, sizeof *pvd, M_PFSVNCACHE, M_WAITOK);
138 if (++pfs_vncache_entries > pfs_vncache_maxentries)
139 pfs_vncache_maxentries = pfs_vncache_entries;
140 error = getnewvnode("pseudofs", mp, pfs_vnodeop_p, vpp);
141 if (error) {
142 FREE(pvd, M_PFSVNCACHE);
143 return (error);
144 }
145 pvd->pvd_pn = pn;
146 pvd->pvd_pid = pid;
147 (*vpp)->v_data = pvd;
148 switch (pn->pn_type) {
149 case pfstype_root:
150 (*vpp)->v_vflag = VV_ROOT;
151 #if 0
152 printf("root vnode allocated\n");
153 #endif
154 /* fall through */
155 case pfstype_dir:
156 case pfstype_this:
157 case pfstype_parent:
158 case pfstype_procdir:
159 (*vpp)->v_type = VDIR;
160 break;
161 case pfstype_file:
162 (*vpp)->v_type = VREG;
163 break;
164 case pfstype_symlink:
165 (*vpp)->v_type = VLNK;
166 break;
167 case pfstype_none:
168 KASSERT(0, ("pfs_vncache_alloc called for null node\n"));
169 default:
170 panic("%s has unexpected type: %d", pn->pn_name, pn->pn_type);
171 }
172 /*
173 * Propagate flag through to vnode so users know it can change
174 * if the process changes (i.e. execve)
175 */
176 if ((pn->pn_flags & PFS_PROCDEP) != 0)
177 (*vpp)->v_vflag |= VV_PROCDEP;
178 pvd->pvd_vnode = *vpp;
179 mtx_lock(&pfs_vncache_mutex);
180 pvd->pvd_prev = NULL;
181 pvd->pvd_next = pfs_vncache;
182 if (pvd->pvd_next)
183 pvd->pvd_next->pvd_prev = pvd;
184 pfs_vncache = pvd;
185 mtx_unlock(&pfs_vncache_mutex);
186 (*vpp)->v_vnlock->lk_flags |= LK_CANRECURSE;
187 vn_lock(*vpp, LK_RETRY | LK_EXCLUSIVE, curthread);
188 return (0);
189 }
190
191 /*
192 * Free a vnode
193 */
194 int
195 pfs_vncache_free(struct vnode *vp)
196 {
197 struct pfs_vdata *pvd;
198
199 mtx_lock(&pfs_vncache_mutex);
200 pvd = (struct pfs_vdata *)vp->v_data;
201 KASSERT(pvd != NULL, ("pfs_vncache_free(): no vnode data\n"));
202 if (pvd->pvd_next)
203 pvd->pvd_next->pvd_prev = pvd->pvd_prev;
204 if (pvd->pvd_prev)
205 pvd->pvd_prev->pvd_next = pvd->pvd_next;
206 else
207 pfs_vncache = pvd->pvd_next;
208 mtx_unlock(&pfs_vncache_mutex);
209
210 --pfs_vncache_entries;
211 FREE(pvd, M_PFSVNCACHE);
212 vp->v_data = NULL;
213 return (0);
214 }
215
216 /*
217 * Free all vnodes associated with a defunct process
218 */
219 static void
220 pfs_exit(void *arg, struct proc *p)
221 {
222 struct pfs_vdata *pvd;
223 struct vnode *vnp;
224
225 mtx_lock(&Giant);
226 /*
227 * This is extremely inefficient due to the fact that vgone() not
228 * only indirectly modifies the vnode cache, but may also sleep.
229 * We can neither hold pfs_vncache_mutex across a vgone() call,
230 * nor make any assumptions about the state of the cache after
231 * vgone() returns. In consequence, we must start over after
232 * every vgone() call, and keep trying until we manage to traverse
233 * the entire cache.
234 *
235 * The only way to improve this situation is to change the data
236 * structure used to implement the cache. An obvious choice in
237 * this particular case would be a BST sorted by PID.
238 */
239 mtx_lock(&pfs_vncache_mutex);
240 pvd = pfs_vncache;
241 while (pvd != NULL) {
242 if (pvd->pvd_pid == p->p_pid) {
243 vnp = pvd->pvd_vnode;
244 mtx_unlock(&pfs_vncache_mutex);
245 vgone(vnp);
246 mtx_lock(&pfs_vncache_mutex);
247 pvd = pfs_vncache;
248 } else {
249 pvd = pvd->pvd_next;
250 }
251 }
252 mtx_unlock(&pfs_vncache_mutex);
253 mtx_unlock(&Giant);
254 }
255
256 /*
257 * Disable a pseudofs node, and free all vnodes associated with it
258 */
259 int
260 pfs_disable(struct pfs_node *pn)
261 {
262 struct pfs_vdata *pvd;
263 struct vnode *vnp;
264
265 if (pn->pn_flags & PFS_DISABLED)
266 return (0);
267 pn->pn_flags |= PFS_DISABLED;
268 /* XXX see comment above nearly identical code in pfs_exit() */
269 mtx_lock(&pfs_vncache_mutex);
270 pvd = pfs_vncache;
271 while (pvd != NULL) {
272 if (pvd->pvd_pn == pn) {
273 vnp = pvd->pvd_vnode;
274 mtx_unlock(&pfs_vncache_mutex);
275 vgone(vnp);
276 mtx_lock(&pfs_vncache_mutex);
277 pvd = pfs_vncache;
278 } else {
279 pvd = pvd->pvd_next;
280 }
281 }
282 mtx_unlock(&pfs_vncache_mutex);
283 return (0);
284 }
285
286 /*
287 * Re-enable a disabled pseudofs node
288 */
289 int
290 pfs_enable(struct pfs_node *pn)
291 {
292 pn->pn_flags &= ~PFS_DISABLED;
293 return (0);
294 }
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