pseudofs_vncache.c revision 89071
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 89071 2002-01-08 11:15:57Z msmith $ 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", 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 /* 110 * See if the vnode is in the cache. 111 * XXX linear search is not very efficient. 112 */ 113 mtx_lock(&pfs_vncache_mutex); 114 for (pvd = pfs_vncache; pvd; pvd = pvd->pvd_next) { 115 if (pvd->pvd_pn == pn && pvd->pvd_pid == pid) { 116 if (vget(pvd->pvd_vnode, 0, curthread) == 0) { 117 ++pfs_vncache_hits; 118 *vpp = pvd->pvd_vnode; 119 mtx_unlock(&pfs_vncache_mutex); 120 /* XXX see comment at top of pfs_lookup() */ 121 cache_purge(*vpp); 122 return (0); 123 } 124 /* XXX if this can happen, we're in trouble */ 125 break; 126 } 127 } 128 mtx_unlock(&pfs_vncache_mutex); 129 ++pfs_vncache_misses; 130 131 /* nope, get a new one */ 132 MALLOC(pvd, struct pfs_vdata *, sizeof *pvd, M_PFSVNCACHE, M_WAITOK); 133 if (++pfs_vncache_entries > pfs_vncache_maxentries) 134 pfs_vncache_maxentries = pfs_vncache_entries; 135 error = getnewvnode(VT_PSEUDOFS, mp, pfs_vnodeop_p, vpp); 136 if (error) 137 return (error); 138 pvd->pvd_pn = pn; 139 pvd->pvd_pid = pid; 140 (*vpp)->v_data = pvd; 141 switch (pn->pn_type) { 142 case pfstype_root: 143 (*vpp)->v_flag = VROOT; 144#if 0 145 printf("root vnode allocated\n"); 146#endif 147 /* fall through */ 148 case pfstype_dir: 149 case pfstype_this: 150 case pfstype_parent: 151 case pfstype_procdir: 152 (*vpp)->v_type = VDIR; 153 break; 154 case pfstype_file: 155 (*vpp)->v_type = VREG; 156 break; 157 case pfstype_symlink: 158 (*vpp)->v_type = VLNK; 159 break; 160 case pfstype_none: 161 KASSERT(0, ("pfs_vncache_alloc called for null node\n")); 162 default: 163 panic("%s has unexpected type: %d", pn->pn_name, pn->pn_type); 164 } 165 pvd->pvd_vnode = *vpp; 166 mtx_lock(&pfs_vncache_mutex); 167 pvd->pvd_prev = NULL; 168 pvd->pvd_next = pfs_vncache; 169 if (pvd->pvd_next) 170 pvd->pvd_next->pvd_prev = pvd; 171 pfs_vncache = pvd; 172 mtx_unlock(&pfs_vncache_mutex); 173 return (0); 174} 175 176/* 177 * Free a vnode 178 */ 179int 180pfs_vncache_free(struct vnode *vp) 181{ 182 struct pfs_vdata *pvd; 183 184 cache_purge(vp); 185 186 mtx_lock(&pfs_vncache_mutex); 187 pvd = (struct pfs_vdata *)vp->v_data; 188 KASSERT(pvd != NULL, ("pfs_vncache_free(): no vnode data\n")); 189 if (pvd->pvd_next) 190 pvd->pvd_next->pvd_prev = pvd->pvd_prev; 191 if (pvd->pvd_prev) 192 pvd->pvd_prev->pvd_next = pvd->pvd_next; 193 else 194 pfs_vncache = pvd->pvd_next; 195 mtx_unlock(&pfs_vncache_mutex); 196 197 --pfs_vncache_entries; 198 FREE(pvd, M_PFSVNCACHE); 199 vp->v_data = NULL; 200 return (0); 201} 202 203/* 204 * Free all vnodes associated with a defunct process 205 */ 206static void 207pfs_exit(struct proc *p) 208{ 209 struct pfs_vdata *pvd, *prev; 210 211 mtx_lock(&pfs_vncache_mutex); 212 /* 213 * The double loop is necessary because vgone() indirectly 214 * calls pfs_vncache_free() which frees pvd, so we have to 215 * backtrace one step every time we free a vnode. 216 */ 217 /* XXX linear search... not very efficient */ 218 for (pvd = pfs_vncache; pvd != NULL; pvd = pvd->pvd_next) { 219 while (pvd != NULL && pvd->pvd_pid == p->p_pid) { 220 prev = pvd->pvd_prev; 221 vgone(pvd->pvd_vnode); 222 pvd = prev ? prev->pvd_next : pfs_vncache; 223 } 224 if (pvd == NULL) 225 break; 226 } 227 mtx_unlock(&pfs_vncache_mutex); 228} 229 230/* 231 * Disable a pseudofs node, and free all vnodes associated with it 232 */ 233int 234pfs_disable(struct pfs_node *pn) 235{ 236 struct pfs_vdata *pvd, *prev; 237 238 if (pn->pn_flags & PFS_DISABLED) 239 return (0); 240 mtx_lock(&pfs_vncache_mutex); 241 pn->pn_flags |= PFS_DISABLED; 242 /* see the comment about the double loop in pfs_exit() */ 243 /* XXX linear search... not very efficient */ 244 for (pvd = pfs_vncache; pvd != NULL; pvd = pvd->pvd_next) { 245 while (pvd != NULL && pvd->pvd_pn == pn) { 246 prev = pvd->pvd_prev; 247 vgone(pvd->pvd_vnode); 248 pvd = prev ? prev->pvd_next : pfs_vncache; 249 } 250 if (pvd == NULL) 251 break; 252 } 253 mtx_unlock(&pfs_vncache_mutex); 254 return (0); 255} 256 257/* 258 * Re-enable a disabled pseudofs node 259 */ 260int 261pfs_enable(struct pfs_node *pn) 262{ 263 pn->pn_flags &= ~PFS_DISABLED; 264 return (0); 265} 266