1 /*- 2 * Copyright (c) 2001 Dag-Erling Co�dan Sm�rgrav 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 29 #include <sys/cdefs.h> 30 __FBSDID("$FreeBSD$"); 31 32 #include "opt_pseudofs.h" 33 34 #include <sys/param.h> 35 #include <sys/kernel.h> 36 #include <sys/systm.h> 37 #include <sys/eventhandler.h> 38 #include <sys/lock.h> 39 #include <sys/malloc.h> 40 #include <sys/mutex.h> 41 #include <sys/proc.h> 42 #include <sys/sysctl.h> 43 #include <sys/vnode.h> 44 45 #include <fs/pseudofs/pseudofs.h> 46 #include <fs/pseudofs/pseudofs_internal.h> 47 48 static MALLOC_DEFINE(M_PFSVNCACHE, "pfs_vncache", "pseudofs vnode cache"); 49 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); 54 55 SYSCTL_NODE(_vfs_pfs, OID_AUTO, vncache, CTLFLAG_RW, 0, 56 "pseudofs vnode cache"); 57 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"); 62 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"); 67 68 static int pfs_vncache_hits; 69 SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, hits, CTLFLAG_RD, 70 &pfs_vncache_hits, 0, 71 "number of cache hits since initialization"); 72 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"); 77 78 extern struct vop_vector pfs_vnodeops; /* XXX -> .h file */ 79 80 /* 81 * Initialize vnode cache 82 */ 83 void 84 pfs_vncache_load(void) 85 { 86 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); 91 } 92 93 /* 94 * Tear down vnode cache 95 */ 96 void 97 pfs_vncache_unload(void) 98 { 99 100 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); 105 } 106 107 /* 108 * Allocate a vnode 109 */ 110 int 111 pfs_vncache_alloc(struct mount *mp, struct vnode **vpp, 112 struct pfs_node *pn, pid_t pid) 113 { 114 struct pfs_vdata *pvd; 115 struct vnode *vp; 116 int error; 117 118 /* 119 * See if the vnode is in the cache. 120 * XXX linear search is not very efficient. 121 */ 122 retry: 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) { 127 vp = pvd->pvd_vnode; 128 VI_LOCK(vp); 129 mtx_unlock(&pfs_vncache_mutex); 130 if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK, curthread) == 0) { 131 ++pfs_vncache_hits; 132 *vpp = vp; 133 /* 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 140 * cache. 141 */ 142 cache_purge(vp); 143 return (0); 144 } 145 goto retry; 146 } 147 } 148 mtx_unlock(&pfs_vncache_mutex); 149 ++pfs_vncache_misses; 150 151 /* nope, get a new one */ 152 MALLOC(pvd, struct pfs_vdata *, sizeof *pvd, M_PFSVNCACHE, M_WAITOK); 153 mtx_lock(&pfs_vncache_mutex); 154 if (++pfs_vncache_entries > pfs_vncache_maxentries) 155 pfs_vncache_maxentries = pfs_vncache_entries; 156 mtx_unlock(&pfs_vncache_mutex); 157 error = getnewvnode("pseudofs", mp, &pfs_vnodeops, vpp); 158 if (error) { 159 mtx_lock(&pfs_vncache_mutex); 160 --pfs_vncache_entries; 161 mtx_unlock(&pfs_vncache_mutex); 162 FREE(pvd, M_PFSVNCACHE); 163 return (error); 164 } 165 pvd->pvd_pn = pn; 166 pvd->pvd_pid = pid; 167 (*vpp)->v_data = pvd; 168 switch (pn->pn_type) { 169 case pfstype_root: 170 (*vpp)->v_vflag = VV_ROOT; 171 #if 0 172 printf("root vnode allocated\n"); 173 #endif 174 /* fall through */ 175 case pfstype_dir: 176 case pfstype_this: 177 case pfstype_parent: 178 case pfstype_procdir: 179 (*vpp)->v_type = VDIR; 180 break; 181 case pfstype_file: 182 (*vpp)->v_type = VREG; 183 break; 184 case pfstype_symlink: 185 (*vpp)->v_type = VLNK; 186 break; 187 case pfstype_none: 188 KASSERT(0, ("pfs_vncache_alloc called for null node\n")); 189 default: 190 panic("%s has unexpected type: %d", pn->pn_name, pn->pn_type); 191 } 192 /* 193 * Propagate flag through to vnode so users know it can change 194 * if the process changes (i.e. execve) 195 */ 196 if ((pn->pn_flags & PFS_PROCDEP) != 0) 197 (*vpp)->v_vflag |= VV_PROCDEP; 198 pvd->pvd_vnode = *vpp; 199 VN_LOCK_AREC(*vpp); 200 vn_lock(*vpp, LK_EXCLUSIVE | LK_RETRY); 201 error = insmntque(*vpp, mp); 202 if (error != 0) { 203 mtx_lock(&pfs_vncache_mutex); 204 --pfs_vncache_entries; 205 mtx_unlock(&pfs_vncache_mutex); 206 FREE(pvd, M_PFSVNCACHE); 207 *vpp = NULLVP; 208 return (error); 209 } 210 mtx_lock(&pfs_vncache_mutex); 211 pvd->pvd_prev = NULL; 212 pvd->pvd_next = pfs_vncache; 213 if (pvd->pvd_next) 214 pvd->pvd_next->pvd_prev = pvd; 215 pfs_vncache = pvd; 216 mtx_unlock(&pfs_vncache_mutex); 217 return (0); 218 } 219 220 /* 221 * Free a vnode 222 */ 223 int 224 pfs_vncache_free(struct vnode *vp) 225 { 226 struct pfs_vdata *pvd; 227 228 mtx_lock(&pfs_vncache_mutex); 229 pvd = (struct pfs_vdata *)vp->v_data; 230 KASSERT(pvd != NULL, ("pfs_vncache_free(): no vnode data\n")); 231 if (pvd->pvd_next) 232 pvd->pvd_next->pvd_prev = pvd->pvd_prev; 233 if (pvd->pvd_prev) 234 pvd->pvd_prev->pvd_next = pvd->pvd_next; 235 else 236 pfs_vncache = pvd->pvd_next; 237 --pfs_vncache_entries; 238 mtx_unlock(&pfs_vncache_mutex); 239 240 FREE(pvd, M_PFSVNCACHE); 241 vp->v_data = NULL; 242 return (0); 243 } 244 245 /* 246 * Purge the cache of dead entries 247 * 248 * This is extremely inefficient due to the fact that vgone() not only 249 * indirectly modifies the vnode cache, but may also sleep. We can 250 * neither hold pfs_vncache_mutex across a vgone() call, nor make any 251 * assumptions about the state of the cache after vgone() returns. In 252 * consequence, we must start over after every vgone() call, and keep 253 * trying until we manage to traverse the entire cache. 254 * 255 * The only way to improve this situation is to change the data structure 256 * used to implement the cache. 257 */ 258 void 259 pfs_purge(struct pfs_node *pn) 260 { 261 struct pfs_vdata *pvd; 262 struct vnode *vnp; 263 264 mtx_lock(&pfs_vncache_mutex); 265 pvd = pfs_vncache; 266 while (pvd != NULL) { 267 if (pvd->pvd_dead || (pn != NULL && pvd->pvd_pn == pn)) { 268 vnp = pvd->pvd_vnode; 269 vhold(vnp); 270 mtx_unlock(&pfs_vncache_mutex); 271 VOP_LOCK(vnp, LK_EXCLUSIVE); 272 vgone(vnp); 273 VOP_UNLOCK(vnp, 0); 274 vdrop(vnp); 275 mtx_lock(&pfs_vncache_mutex); 276 pvd = pfs_vncache; 277 } else { 278 pvd = pvd->pvd_next; 279 } 280 } 281 mtx_unlock(&pfs_vncache_mutex); 282 } 283 284 /* 285 * Free all vnodes associated with a defunct process 286 * 287 * XXXRW: It is unfortunate that pfs_exit() always acquires and releases two 288 * mutexes (one of which is Giant) for every process exit, even if procfs 289 * isn't mounted. 290 */ 291 static void 292 pfs_exit(void *arg, struct proc *p) 293 { 294 struct pfs_vdata *pvd; 295 int dead; 296 297 if (pfs_vncache == NULL) 298 return; 299 mtx_lock(&Giant); 300 mtx_lock(&pfs_vncache_mutex); 301 for (pvd = pfs_vncache, dead = 0; pvd != NULL; pvd = pvd->pvd_next) 302 if (pvd->pvd_pid == p->p_pid) 303 dead = pvd->pvd_dead = 1; 304 mtx_unlock(&pfs_vncache_mutex); 305 if (dead) 306 pfs_purge(NULL); 307 mtx_unlock(&Giant); 308 } 309