pseudofs_vncache.c revision 84386
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 84386 2001-10-02 22:22:42Z 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 if (pfs_vncache_entries != 0) 96 printf("pfs_vncache_unload(): %d entries remaining\n", 97 pfs_vncache_entries); 98 mtx_destroy(&pfs_vncache_mutex); 99} 100 101/* 102 * Allocate a vnode 103 */ 104int 105pfs_vncache_alloc(struct mount *mp, struct vnode **vpp, 106 struct pfs_node *pn, pid_t pid) 107{ 108 struct pfs_vdata *pvd; 109 int error; 110 111 /* see if the vnode is in the cache */ 112 /* XXX linear search... not very efficient */ 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 return (0); 121 } 122 /* XXX if this can happen, we're in trouble */ 123 break; 124 } 125 } 126 mtx_unlock(&pfs_vncache_mutex); 127 ++pfs_vncache_misses; 128 129 /* nope, get a new one */ 130 MALLOC(pvd, struct pfs_vdata *, sizeof *pvd, M_PFSVNCACHE, M_WAITOK); 131 if (++pfs_vncache_entries > pfs_vncache_maxentries) 132 pfs_vncache_maxentries = pfs_vncache_entries; 133 error = getnewvnode(VT_PSEUDOFS, mp, pfs_vnodeop_p, vpp); 134 if (error) 135 return (error); 136 pvd->pvd_pn = pn; 137 pvd->pvd_pid = pid; 138 (*vpp)->v_data = pvd; 139 switch (pn->pn_type) { 140 case pfstype_root: 141 (*vpp)->v_flag = VROOT; 142#if 0 143 printf("root vnode allocated\n"); 144#endif 145 /* fall through */ 146 case pfstype_dir: 147 case pfstype_this: 148 case pfstype_parent: 149 case pfstype_procdir: 150 (*vpp)->v_type = VDIR; 151 break; 152 case pfstype_file: 153 (*vpp)->v_type = VREG; 154 break; 155 case pfstype_symlink: 156 (*vpp)->v_type = VLNK; 157 break; 158 case pfstype_none: 159 KASSERT(0, ("pfs_vncache_alloc called for null node\n")); 160 default: 161 panic("%s has unexpected type: %d", pn->pn_name, pn->pn_type); 162 } 163 pvd->pvd_vnode = *vpp; 164 mtx_lock(&pfs_vncache_mutex); 165 pvd->pvd_prev = NULL; 166 pvd->pvd_next = pfs_vncache; 167 if (pvd->pvd_next) 168 pvd->pvd_next->pvd_prev = pvd; 169 pfs_vncache = pvd; 170 mtx_unlock(&pfs_vncache_mutex); 171 return (0); 172} 173 174/* 175 * Free a vnode 176 */ 177int 178pfs_vncache_free(struct vnode *vp) 179{ 180 struct pfs_vdata *pvd; 181 182 mtx_lock(&pfs_vncache_mutex); 183 pvd = (struct pfs_vdata *)vp->v_data; 184 KASSERT(pvd != NULL, ("pfs_vncache_free(): no vnode data\n")); 185 if (pvd->pvd_next) 186 pvd->pvd_next->pvd_prev = pvd->pvd_prev; 187 if (pvd->pvd_prev) 188 pvd->pvd_prev->pvd_next = pvd->pvd_next; 189 else 190 pfs_vncache = pvd->pvd_next; 191 mtx_unlock(&pfs_vncache_mutex); 192 193 --pfs_vncache_entries; 194 FREE(pvd, M_PFSVNCACHE); 195 vp->v_data = NULL; 196 return (0); 197} 198 199/* 200 * Free all vnodes associated with a defunct process 201 */ 202static void 203pfs_exit(struct proc *p) 204{ 205 struct pfs_vdata *pvd, *prev; 206 207 mtx_lock(&pfs_vncache_mutex); 208 /* 209 * The double loop is necessary because vgone() indirectly 210 * calls pfs_vncache_free() which frees pvd, so we have to 211 * backtrace one step every time we free a vnode. 212 */ 213 /* XXX linear search... not very efficient */ 214 for (pvd = pfs_vncache; pvd != NULL; pvd = pvd->pvd_next) { 215 while (pvd != NULL && pvd->pvd_pid == p->p_pid) { 216 prev = pvd->pvd_prev; 217 vgone(pvd->pvd_vnode); 218 pvd = prev ? prev->pvd_next : pfs_vncache; 219 } 220 } 221 mtx_unlock(&pfs_vncache_mutex); 222} 223 224/* 225 * Disable a pseudofs node, and free all vnodes associated with it 226 */ 227int 228pfs_disable(struct pfs_node *pn) 229{ 230 struct pfs_vdata *pvd, *prev; 231 232 if (pn->pn_flags & PFS_DISABLED) 233 return (0); 234 mtx_lock(&pfs_vncache_mutex); 235 pn->pn_flags |= PFS_DISABLED; 236 /* see the comment about the double loop in pfs_exit() */ 237 /* XXX linear search... not very efficient */ 238 for (pvd = pfs_vncache; pvd != NULL; pvd = pvd->pvd_next) { 239 while (pvd != NULL && pvd->pvd_pn == pn) { 240 prev = pvd->pvd_prev; 241 vgone(pvd->pvd_vnode); 242 pvd = prev ? prev->pvd_next : pfs_vncache; 243 } 244 } 245 mtx_unlock(&pfs_vncache_mutex); 246 return (0); 247} 248 249/* 250 * Re-enable a disabled pseudofs node 251 */ 252int 253pfs_enable(struct pfs_node *pn) 254{ 255 pn->pn_flags &= ~PFS_DISABLED; 256 return (0); 257} 258