pseudofs_vncache.c revision 84246
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 84246 2001-10-01 04:22:20Z des $ 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/mount.h> 37#include <sys/mutex.h> 38#include <sys/proc.h> 39#include <sys/sbuf.h> 40#include <sys/sysctl.h> 41#include <sys/vnode.h> 42 43#include <fs/pseudofs/pseudofs.h> 44#include <fs/pseudofs/pseudofs_internal.h> 45 46static MALLOC_DEFINE(M_PFSVNCACHE, "pfs_vncache", "pseudofs vnode cache"); 47 48static struct mtx pfs_vncache_mutex; 49struct pfs_vdata *pfs_vncache; 50static void pfs_exit(struct proc *p); 51 52SYSCTL_NODE(_vfs_pfs, OID_AUTO, vncache, CTLFLAG_RW, 0, 53 "pseudofs vnode cache"); 54 55static int pfs_vncache_entries; 56SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, entries, CTLFLAG_RD, 57 &pfs_vncache_entries, 0, 58 "number of entries in the vnode cache"); 59 60static int pfs_vncache_maxentries; 61SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, maxentries, CTLFLAG_RD, 62 &pfs_vncache_maxentries, 0, 63 "highest number of entries in the vnode cache"); 64 65static int pfs_vncache_hits; 66SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, hits, CTLFLAG_RD, 67 &pfs_vncache_hits, 0, 68 "number of cache hits since initialization"); 69 70static int pfs_vncache_misses; 71SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, misses, CTLFLAG_RD, 72 &pfs_vncache_misses, 0, 73 "number of cache misses since initialization"); 74 75extern vop_t **pfs_vnodeop_p; 76 77/* 78 * Initialize vnode cache 79 */ 80void 81pfs_vncache_load(void) 82{ 83 mtx_init(&pfs_vncache_mutex, "pseudofs_vncache", MTX_DEF|MTX_RECURSE); 84 /* XXX at_exit() can fail with ENOMEN */ 85 at_exit(pfs_exit); 86} 87 88/* 89 * Tear down vnode cache 90 */ 91void 92pfs_vncache_unload(void) 93{ 94 rm_at_exit(pfs_exit); 95 mtx_destroy(&pfs_vncache_mutex); 96} 97 98/* 99 * Allocate a vnode 100 */ 101int 102pfs_vncache_alloc(struct mount *mp, struct vnode **vpp, 103 struct pfs_node *pn, pid_t pid) 104{ 105 struct pfs_vdata *pvd; 106 int error; 107 108 /* see if the vnode is in the cache */ 109 /* XXX linear search... not very efficient */ 110 mtx_lock(&pfs_vncache_mutex); 111 for (pvd = pfs_vncache; pvd; pvd = pvd->pvd_next) { 112 if (pvd->pvd_pn == pn && pvd->pvd_pid == pid) { 113 if (vget(pvd->pvd_vnode, 0, curthread) == 0) { 114 ++pfs_vncache_hits; 115 *vpp = pvd->pvd_vnode; 116 mtx_unlock(&pfs_vncache_mutex); 117 return (0); 118 } 119 /* XXX if this can happen, we're in trouble */ 120 break; 121 } 122 } 123 mtx_unlock(&pfs_vncache_mutex); 124 ++pfs_vncache_misses; 125 126 /* nope, get a new one */ 127 MALLOC(pvd, struct pfs_vdata *, sizeof *pvd, M_PFSVNCACHE, M_WAITOK); 128 if (++pfs_vncache_entries > pfs_vncache_maxentries) 129 pfs_vncache_maxentries = pfs_vncache_entries; 130 error = getnewvnode(VT_PSEUDOFS, mp, pfs_vnodeop_p, vpp); 131 if (error) 132 return (error); 133 pvd->pvd_pn = pn; 134 pvd->pvd_pid = pid; 135 (*vpp)->v_data = pvd; 136 switch (pn->pn_type) { 137 case pfstype_root: 138 (*vpp)->v_flag = VROOT; 139#if 0 140 printf("root vnode allocated\n"); 141#endif 142 /* fall through */ 143 case pfstype_dir: 144 case pfstype_this: 145 case pfstype_parent: 146 case pfstype_procdir: 147 (*vpp)->v_type = VDIR; 148 break; 149 case pfstype_file: 150 (*vpp)->v_type = VREG; 151 break; 152 case pfstype_symlink: 153 (*vpp)->v_type = VLNK; 154 break; 155 case pfstype_none: 156 KASSERT(0, ("pfs_vncache_alloc called for null node\n")); 157 default: 158 panic("%s has unexpected type: %d", pn->pn_name, pn->pn_type); 159 } 160 pvd->pvd_vnode = *vpp; 161 mtx_lock(&pfs_vncache_mutex); 162 pvd->pvd_prev = NULL; 163 pvd->pvd_next = pfs_vncache; 164 if (pvd->pvd_next) 165 pvd->pvd_next->pvd_prev = pvd; 166 pfs_vncache = pvd; 167 mtx_unlock(&pfs_vncache_mutex); 168 return (0); 169} 170 171/* 172 * Free a vnode 173 */ 174int 175pfs_vncache_free(struct vnode *vp) 176{ 177 struct pfs_vdata *pvd; 178 179 mtx_lock(&pfs_vncache_mutex); 180 pvd = (struct pfs_vdata *)vp->v_data; 181 KASSERT(pvd != NULL, ("pfs_vncache_free(): no vnode data\n")); 182 if (pvd->pvd_next) 183 pvd->pvd_next->pvd_prev = pvd->pvd_prev; 184 if (pvd->pvd_prev) 185 pvd->pvd_prev->pvd_next = pvd->pvd_next; 186 else 187 pfs_vncache = pvd->pvd_next; 188 mtx_unlock(&pfs_vncache_mutex); 189 190 --pfs_vncache_entries; 191 FREE(pvd, M_PFSVNCACHE); 192 vp->v_data = NULL; 193 return (0); 194} 195 196/* 197 * Free all vnodes associated with a defunct process 198 */ 199static void 200pfs_exit(struct proc *p) 201{ 202 struct pfs_vdata *pvd, *prev; 203 204 mtx_lock(&pfs_vncache_mutex); 205 /* 206 * The double loop is necessary because vgone() indirectly 207 * calls pfs_vncache_free() which frees pvd, so we have to 208 * backtrace one step every time we free a vnode. 209 */ 210 /* XXX linear search... not very efficient */ 211 for (pvd = pfs_vncache; pvd != NULL; pvd = pvd->pvd_next) { 212 while (pvd != NULL && pvd->pvd_pid == p->p_pid) { 213 prev = pvd->pvd_prev; 214 vgone(pvd->pvd_vnode); 215 pvd = prev ? prev->pvd_next : pfs_vncache; 216 } 217 } 218 mtx_unlock(&pfs_vncache_mutex); 219} 220