pseudofs_vncache.c revision 105165
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 * $FreeBSD: head/sys/fs/pseudofs/pseudofs_vncache.c 105165 2002-10-15 18:51:02Z phk $ 29 */ 30 31#include <sys/param.h> 32#include <sys/kernel.h> 33#include <sys/systm.h> 34#include <sys/lock.h> 35#include <sys/malloc.h> 36#include <sys/mutex.h> 37#include <sys/proc.h> 38#include <sys/sysctl.h> 39#include <sys/vnode.h> 40 41#include <fs/pseudofs/pseudofs.h> 42#include <fs/pseudofs/pseudofs_internal.h> 43 44static MALLOC_DEFINE(M_PFSVNCACHE, "pfs_vncache", "pseudofs vnode cache"); 45 46static struct mtx pfs_vncache_mutex; 47static struct pfs_vdata *pfs_vncache; 48static void pfs_exit(struct proc *p); 49 50SYSCTL_NODE(_vfs_pfs, OID_AUTO, vncache, CTLFLAG_RW, 0, 51 "pseudofs vnode cache"); 52 53static int pfs_vncache_entries; 54SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, entries, CTLFLAG_RD, 55 &pfs_vncache_entries, 0, 56 "number of entries in the vnode cache"); 57 58static int pfs_vncache_maxentries; 59SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, maxentries, CTLFLAG_RD, 60 &pfs_vncache_maxentries, 0, 61 "highest number of entries in the vnode cache"); 62 63static int pfs_vncache_hits; 64SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, hits, CTLFLAG_RD, 65 &pfs_vncache_hits, 0, 66 "number of cache hits since initialization"); 67 68static int pfs_vncache_misses; 69SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, misses, CTLFLAG_RD, 70 &pfs_vncache_misses, 0, 71 "number of cache misses since initialization"); 72 73extern vop_t **pfs_vnodeop_p; 74 75/* 76 * Initialize vnode cache 77 */ 78void 79pfs_vncache_load(void) 80{ 81 mtx_init(&pfs_vncache_mutex, "pseudofs_vncache", NULL, 82 MTX_DEF | MTX_RECURSE); 83 /* XXX at_exit() can fail with ENOMEN */ 84 at_exit(pfs_exit); 85} 86 87/* 88 * Tear down vnode cache 89 */ 90void 91pfs_vncache_unload(void) 92{ 93 rm_at_exit(pfs_exit); 94 if (pfs_vncache_entries != 0) 95 printf("pfs_vncache_unload(): %d entries remaining\n", 96 pfs_vncache_entries); 97 mtx_destroy(&pfs_vncache_mutex); 98} 99 100/* 101 * Allocate a vnode 102 */ 103int 104pfs_vncache_alloc(struct mount *mp, struct vnode **vpp, 105 struct pfs_node *pn, pid_t pid) 106{ 107 struct pfs_vdata *pvd; 108 int error; 109 110 /* 111 * See if the vnode is in the cache. 112 * XXX linear search is not very efficient. 113 */ 114 mtx_lock(&pfs_vncache_mutex); 115 for (pvd = pfs_vncache; pvd; pvd = pvd->pvd_next) { 116 if (pvd->pvd_pn == pn && pvd->pvd_pid == pid) { 117 if (vget(pvd->pvd_vnode, 0, curthread) == 0) { 118 ++pfs_vncache_hits; 119 *vpp = pvd->pvd_vnode; 120 mtx_unlock(&pfs_vncache_mutex); 121 /* XXX see comment at top of pfs_lookup() */ 122 cache_purge(*vpp); 123 vn_lock(*vpp, LK_RETRY | LK_EXCLUSIVE, 124 curthread); 125 return (0); 126 } 127 /* XXX if this can happen, we're in trouble */ 128 break; 129 } 130 } 131 mtx_unlock(&pfs_vncache_mutex); 132 ++pfs_vncache_misses; 133 134 /* nope, get a new one */ 135 MALLOC(pvd, struct pfs_vdata *, sizeof *pvd, M_PFSVNCACHE, M_WAITOK); 136 if (++pfs_vncache_entries > pfs_vncache_maxentries) 137 pfs_vncache_maxentries = pfs_vncache_entries; 138 error = getnewvnode("pseudofs", mp, pfs_vnodeop_p, vpp); 139 if (error) { 140 FREE(pvd, M_PFSVNCACHE); 141 return (error); 142 } 143 pvd->pvd_pn = pn; 144 pvd->pvd_pid = pid; 145 (*vpp)->v_data = pvd; 146 switch (pn->pn_type) { 147 case pfstype_root: 148 (*vpp)->v_vflag = VV_ROOT; 149#if 0 150 printf("root vnode allocated\n"); 151#endif 152 /* fall through */ 153 case pfstype_dir: 154 case pfstype_this: 155 case pfstype_parent: 156 case pfstype_procdir: 157 (*vpp)->v_type = VDIR; 158 break; 159 case pfstype_file: 160 (*vpp)->v_type = VREG; 161 break; 162 case pfstype_symlink: 163 (*vpp)->v_type = VLNK; 164 break; 165 case pfstype_none: 166 KASSERT(0, ("pfs_vncache_alloc called for null node\n")); 167 default: 168 panic("%s has unexpected type: %d", pn->pn_name, pn->pn_type); 169 } 170 /* 171 * Propagate flag through to vnode so users know it can change 172 * if the process changes (i.e. execve) 173 */ 174 if ((pn->pn_flags & PFS_PROCDEP) != 0) 175 (*vpp)->v_vflag |= VV_PROCDEP; 176 pvd->pvd_vnode = *vpp; 177 mtx_lock(&pfs_vncache_mutex); 178 pvd->pvd_prev = NULL; 179 pvd->pvd_next = pfs_vncache; 180 if (pvd->pvd_next) 181 pvd->pvd_next->pvd_prev = pvd; 182 pfs_vncache = pvd; 183 mtx_unlock(&pfs_vncache_mutex); 184 (*vpp)->v_vnlock->lk_flags |= LK_CANRECURSE; 185 vn_lock(*vpp, LK_RETRY | LK_EXCLUSIVE, curthread); 186 return (0); 187} 188 189/* 190 * Free a vnode 191 */ 192int 193pfs_vncache_free(struct vnode *vp) 194{ 195 struct pfs_vdata *pvd; 196 197 cache_purge(vp); 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 */ 219static void 220pfs_exit(struct proc *p) 221{ 222 struct pfs_vdata *pvd, *prev; 223 224 mtx_lock(&pfs_vncache_mutex); 225 /* 226 * The double loop is necessary because vgone() indirectly 227 * calls pfs_vncache_free() which frees pvd, so we have to 228 * backtrace one step every time we free a vnode. 229 */ 230 /* XXX linear search... not very efficient */ 231 for (pvd = pfs_vncache; pvd != NULL; pvd = pvd->pvd_next) { 232 while (pvd != NULL && pvd->pvd_pid == p->p_pid) { 233 prev = pvd->pvd_prev; 234 vgone(pvd->pvd_vnode); 235 pvd = prev ? prev->pvd_next : pfs_vncache; 236 } 237 if (pvd == NULL) 238 break; 239 } 240 mtx_unlock(&pfs_vncache_mutex); 241} 242 243/* 244 * Disable a pseudofs node, and free all vnodes associated with it 245 */ 246int 247pfs_disable(struct pfs_node *pn) 248{ 249 struct pfs_vdata *pvd, *prev; 250 251 if (pn->pn_flags & PFS_DISABLED) 252 return (0); 253 mtx_lock(&pfs_vncache_mutex); 254 pn->pn_flags |= PFS_DISABLED; 255 /* see the comment about the double loop in pfs_exit() */ 256 /* XXX linear search... not very efficient */ 257 for (pvd = pfs_vncache; pvd != NULL; pvd = pvd->pvd_next) { 258 while (pvd != NULL && pvd->pvd_pn == pn) { 259 prev = pvd->pvd_prev; 260 vgone(pvd->pvd_vnode); 261 pvd = prev ? prev->pvd_next : pfs_vncache; 262 } 263 if (pvd == NULL) 264 break; 265 } 266 mtx_unlock(&pfs_vncache_mutex); 267 return (0); 268} 269 270/* 271 * Re-enable a disabled pseudofs node 272 */ 273int 274pfs_enable(struct pfs_node *pn) 275{ 276 pn->pn_flags &= ~PFS_DISABLED; 277 return (0); 278} 279