pseudofs_vncache.c revision 85940
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 85940 2001-11-03 03:07:09Z 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/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; 47struct 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", MTX_DEF|MTX_RECURSE); 82 /* XXX at_exit() can fail with ENOMEN */ 83 at_exit(pfs_exit); 84} 85 86/* 87 * Tear down vnode cache 88 */ 89void 90pfs_vncache_unload(void) 91{ 92 rm_at_exit(pfs_exit); 93 if (pfs_vncache_entries != 0) 94 printf("pfs_vncache_unload(): %d entries remaining\n", 95 pfs_vncache_entries); 96 mtx_destroy(&pfs_vncache_mutex); 97} 98 99/* 100 * Allocate a vnode 101 */ 102int 103pfs_vncache_alloc(struct mount *mp, struct vnode **vpp, 104 struct pfs_node *pn, pid_t pid) 105{ 106 struct pfs_vdata *pvd; 107 int error; 108 109 /* see if the vnode is in the cache */ 110 /* XXX linear search... not very efficient */ 111 mtx_lock(&pfs_vncache_mutex); 112 for (pvd = pfs_vncache; pvd; pvd = pvd->pvd_next) { 113 if (pvd->pvd_pn == pn && pvd->pvd_pid == pid) { 114 if (vget(pvd->pvd_vnode, 0, curthread) == 0) { 115 ++pfs_vncache_hits; 116 *vpp = pvd->pvd_vnode; 117 mtx_unlock(&pfs_vncache_mutex); 118 return (0); 119 } 120 /* XXX if this can happen, we're in trouble */ 121 break; 122 } 123 } 124 mtx_unlock(&pfs_vncache_mutex); 125 ++pfs_vncache_misses; 126 127 /* nope, get a new one */ 128 MALLOC(pvd, struct pfs_vdata *, sizeof *pvd, M_PFSVNCACHE, M_WAITOK); 129 if (++pfs_vncache_entries > pfs_vncache_maxentries) 130 pfs_vncache_maxentries = pfs_vncache_entries; 131 error = getnewvnode(VT_PSEUDOFS, mp, pfs_vnodeop_p, vpp); 132 if (error) 133 return (error); 134 pvd->pvd_pn = pn; 135 pvd->pvd_pid = pid; 136 (*vpp)->v_data = pvd; 137 switch (pn->pn_type) { 138 case pfstype_root: 139 (*vpp)->v_flag = VROOT; 140#if 0 141 printf("root vnode allocated\n"); 142#endif 143 /* fall through */ 144 case pfstype_dir: 145 case pfstype_this: 146 case pfstype_parent: 147 case pfstype_procdir: 148 (*vpp)->v_type = VDIR; 149 break; 150 case pfstype_file: 151 (*vpp)->v_type = VREG; 152 break; 153 case pfstype_symlink: 154 (*vpp)->v_type = VLNK; 155 break; 156 case pfstype_none: 157 KASSERT(0, ("pfs_vncache_alloc called for null node\n")); 158 default: 159 panic("%s has unexpected type: %d", pn->pn_name, pn->pn_type); 160 } 161 pvd->pvd_vnode = *vpp; 162 mtx_lock(&pfs_vncache_mutex); 163 pvd->pvd_prev = NULL; 164 pvd->pvd_next = pfs_vncache; 165 if (pvd->pvd_next) 166 pvd->pvd_next->pvd_prev = pvd; 167 pfs_vncache = pvd; 168 mtx_unlock(&pfs_vncache_mutex); 169 return (0); 170} 171 172/* 173 * Free a vnode 174 */ 175int 176pfs_vncache_free(struct vnode *vp) 177{ 178 struct pfs_vdata *pvd; 179 180 mtx_lock(&pfs_vncache_mutex); 181 pvd = (struct pfs_vdata *)vp->v_data; 182 KASSERT(pvd != NULL, ("pfs_vncache_free(): no vnode data\n")); 183 if (pvd->pvd_next) 184 pvd->pvd_next->pvd_prev = pvd->pvd_prev; 185 if (pvd->pvd_prev) 186 pvd->pvd_prev->pvd_next = pvd->pvd_next; 187 else 188 pfs_vncache = pvd->pvd_next; 189 mtx_unlock(&pfs_vncache_mutex); 190 191 --pfs_vncache_entries; 192 FREE(pvd, M_PFSVNCACHE); 193 vp->v_data = NULL; 194 return (0); 195} 196 197/* 198 * Free all vnodes associated with a defunct process 199 */ 200static void 201pfs_exit(struct proc *p) 202{ 203 struct pfs_vdata *pvd, *prev; 204 205 mtx_lock(&pfs_vncache_mutex); 206 /* 207 * The double loop is necessary because vgone() indirectly 208 * calls pfs_vncache_free() which frees pvd, so we have to 209 * backtrace one step every time we free a vnode. 210 */ 211 /* XXX linear search... not very efficient */ 212 for (pvd = pfs_vncache; pvd != NULL; pvd = pvd->pvd_next) { 213 while (pvd != NULL && pvd->pvd_pid == p->p_pid) { 214 prev = pvd->pvd_prev; 215 vgone(pvd->pvd_vnode); 216 pvd = prev ? prev->pvd_next : pfs_vncache; 217 } 218 } 219 mtx_unlock(&pfs_vncache_mutex); 220} 221 222/* 223 * Disable a pseudofs node, and free all vnodes associated with it 224 */ 225int 226pfs_disable(struct pfs_node *pn) 227{ 228 struct pfs_vdata *pvd, *prev; 229 230 if (pn->pn_flags & PFS_DISABLED) 231 return (0); 232 mtx_lock(&pfs_vncache_mutex); 233 pn->pn_flags |= PFS_DISABLED; 234 /* see the comment about the double loop in pfs_exit() */ 235 /* XXX linear search... not very efficient */ 236 for (pvd = pfs_vncache; pvd != NULL; pvd = pvd->pvd_next) { 237 while (pvd != NULL && pvd->pvd_pn == pn) { 238 prev = pvd->pvd_prev; 239 vgone(pvd->pvd_vnode); 240 pvd = prev ? prev->pvd_next : pfs_vncache; 241 } 242 } 243 mtx_unlock(&pfs_vncache_mutex); 244 return (0); 245} 246 247/* 248 * Re-enable a disabled pseudofs node 249 */ 250int 251pfs_enable(struct pfs_node *pn) 252{ 253 pn->pn_flags &= ~PFS_DISABLED; 254 return (0); 255} 256