1 /*- 2 * Copyright (c) 1989, 1993, 1995 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Poul-Henning Kamp of the FreeBSD Project. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 4. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * @(#)vfs_cache.c 8.5 (Berkeley) 3/22/95 33 */ 34 35 #include <sys/cdefs.h> 36 __FBSDID("$FreeBSD$"); 37 38 #include <sys/param.h> 39 #include <sys/systm.h> 40 #include <sys/kernel.h> 41 #include <sys/lock.h> 42 #include <sys/mutex.h> 43 #include <sys/sysctl.h> 44 #include <sys/mount.h> 45 #include <sys/vnode.h> 46 #include <sys/namei.h> 47 #include <sys/malloc.h> 48 #include <sys/syscallsubr.h> 49 #include <sys/sysproto.h> 50 #include <sys/proc.h> 51 #include <sys/filedesc.h> 52 #include <sys/fnv_hash.h> 53 54 #include <vm/uma.h> 55 56 /* 57 * This structure describes the elements in the cache of recent 58 * names looked up by namei. 59 */ 60 61 struct namecache { 62 LIST_ENTRY(namecache) nc_hash; /* hash chain */ 63 LIST_ENTRY(namecache) nc_src; /* source vnode list */ 64 TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */ 65 struct vnode *nc_dvp; /* vnode of parent of name */ 66 struct vnode *nc_vp; /* vnode the name refers to */ 67 u_char nc_flag; /* flag bits */ 68 u_char nc_nlen; /* length of name */ 69 char nc_name[0]; /* segment name */ 70 }; 71 72 /* 73 * Name caching works as follows: 74 * 75 * Names found by directory scans are retained in a cache 76 * for future reference. It is managed LRU, so frequently 77 * used names will hang around. Cache is indexed by hash value 78 * obtained from (vp, name) where vp refers to the directory 79 * containing name. 80 * 81 * If it is a "negative" entry, (i.e. for a name that is known NOT to 82 * exist) the vnode pointer will be NULL. 83 * 84 * Upon reaching the last segment of a path, if the reference 85 * is for DELETE, or NOCACHE is set (rewrite), and the 86 * name is located in the cache, it will be dropped. 87 */ 88 89 /* 90 * Structures associated with name cacheing. 91 */ 92 #define NCHHASH(hash) \ 93 (&nchashtbl[(hash) & nchash]) 94 static LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */ 95 static TAILQ_HEAD(, namecache) ncneg; /* Hash Table */ 96 static u_long nchash; /* size of hash table */ 97 SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, ""); 98 static u_long ncnegfactor = 16; /* ratio of negative entries */ 99 SYSCTL_ULONG(_debug, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, ""); 100 static u_long numneg; /* number of cache entries allocated */ 101 SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, ""); 102 static u_long numcache; /* number of cache entries allocated */ 103 SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, ""); 104 static u_long numcachehv; /* number of cache entries with vnodes held */ 105 SYSCTL_ULONG(_debug, OID_AUTO, numcachehv, CTLFLAG_RD, &numcachehv, 0, ""); 106 #if 0 107 static u_long numcachepl; /* number of cache purge for leaf entries */ 108 SYSCTL_ULONG(_debug, OID_AUTO, numcachepl, CTLFLAG_RD, &numcachepl, 0, ""); 109 #endif 110 struct nchstats nchstats; /* cache effectiveness statistics */ 111 112 static struct mtx cache_lock; 113 MTX_SYSINIT(vfscache, &cache_lock, "Name Cache", MTX_DEF); 114 115 #define CACHE_LOCK() mtx_lock(&cache_lock) 116 #define CACHE_UNLOCK() mtx_unlock(&cache_lock) 117 118 /* 119 * UMA zones for the VFS cache. 120 * 121 * The small cache is used for entries with short names, which are the 122 * most common. The large cache is used for entries which are too big to 123 * fit in the small cache. 124 */ 125 static uma_zone_t cache_zone_small; 126 static uma_zone_t cache_zone_large; 127 128 #define CACHE_PATH_CUTOFF 32 129 #define CACHE_ZONE_SMALL (sizeof(struct namecache) + CACHE_PATH_CUTOFF) 130 #define CACHE_ZONE_LARGE (sizeof(struct namecache) + NAME_MAX) 131 132 #define cache_alloc(len) uma_zalloc(((len) <= CACHE_PATH_CUTOFF) ? \ 133 cache_zone_small : cache_zone_large, M_WAITOK) 134 #define cache_free(ncp) do { \ 135 if (ncp != NULL) \ 136 uma_zfree(((ncp)->nc_nlen <= CACHE_PATH_CUTOFF) ? \ 137 cache_zone_small : cache_zone_large, (ncp)); \ 138 } while (0) 139 140 static int doingcache = 1; /* 1 => enable the cache */ 141 SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0, ""); 142 143 /* Export size information to userland */ 144 SYSCTL_INT(_debug_sizeof, OID_AUTO, namecache, CTLFLAG_RD, 0, 145 sizeof(struct namecache), ""); 146 147 /* 148 * The new name cache statistics 149 */ 150 static SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, "Name cache statistics"); 151 #define STATNODE(mode, name, var) \ 152 SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, mode, var, 0, ""); 153 STATNODE(CTLFLAG_RD, numneg, &numneg); 154 STATNODE(CTLFLAG_RD, numcache, &numcache); 155 static u_long numcalls; STATNODE(CTLFLAG_RD, numcalls, &numcalls); 156 static u_long dothits; STATNODE(CTLFLAG_RD, dothits, &dothits); 157 static u_long dotdothits; STATNODE(CTLFLAG_RD, dotdothits, &dotdothits); 158 static u_long numchecks; STATNODE(CTLFLAG_RD, numchecks, &numchecks); 159 static u_long nummiss; STATNODE(CTLFLAG_RD, nummiss, &nummiss); 160 static u_long nummisszap; STATNODE(CTLFLAG_RD, nummisszap, &nummisszap); 161 static u_long numposzaps; STATNODE(CTLFLAG_RD, numposzaps, &numposzaps); 162 static u_long numposhits; STATNODE(CTLFLAG_RD, numposhits, &numposhits); 163 static u_long numnegzaps; STATNODE(CTLFLAG_RD, numnegzaps, &numnegzaps); 164 static u_long numneghits; STATNODE(CTLFLAG_RD, numneghits, &numneghits); 165 166 SYSCTL_OPAQUE(_vfs_cache, OID_AUTO, nchstats, CTLFLAG_RD, &nchstats, 167 sizeof(nchstats), "LU", "VFS cache effectiveness statistics"); 168 169 170 171 static void cache_zap(struct namecache *ncp); 172 static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 173 char *buf, char **retbuf, u_int buflen); 174 175 static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); 176 177 /* 178 * Flags in namecache.nc_flag 179 */ 180 #define NCF_WHITE 1 181 182 /* 183 * Grab an atomic snapshot of the name cache hash chain lengths 184 */ 185 SYSCTL_NODE(_debug, OID_AUTO, hashstat, CTLFLAG_RW, NULL, "hash table stats"); 186 187 static int 188 sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS) 189 { 190 int error; 191 struct nchashhead *ncpp; 192 struct namecache *ncp; 193 int n_nchash; 194 int count; 195 196 n_nchash = nchash + 1; /* nchash is max index, not count */ 197 if (!req->oldptr) 198 return SYSCTL_OUT(req, 0, n_nchash * sizeof(int)); 199 200 /* Scan hash tables for applicable entries */ 201 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { 202 CACHE_LOCK(); 203 count = 0; 204 LIST_FOREACH(ncp, ncpp, nc_hash) { 205 count++; 206 } 207 CACHE_UNLOCK(); 208 error = SYSCTL_OUT(req, &count, sizeof(count)); 209 if (error) 210 return (error); 211 } 212 return (0); 213 } 214 SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD, 215 0, 0, sysctl_debug_hashstat_rawnchash, "S,int", "nchash chain lengths"); 216 217 static int 218 sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS) 219 { 220 int error; 221 struct nchashhead *ncpp; 222 struct namecache *ncp; 223 int n_nchash; 224 int count, maxlength, used, pct; 225 226 if (!req->oldptr) 227 return SYSCTL_OUT(req, 0, 4 * sizeof(int)); 228 229 n_nchash = nchash + 1; /* nchash is max index, not count */ 230 used = 0; 231 maxlength = 0; 232 233 /* Scan hash tables for applicable entries */ 234 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { 235 count = 0; 236 CACHE_LOCK(); 237 LIST_FOREACH(ncp, ncpp, nc_hash) { 238 count++; 239 } 240 CACHE_UNLOCK(); 241 if (count) 242 used++; 243 if (maxlength < count) 244 maxlength = count; 245 } 246 n_nchash = nchash + 1; 247 pct = (used * 100 * 100) / n_nchash; 248 error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash)); 249 if (error) 250 return (error); 251 error = SYSCTL_OUT(req, &used, sizeof(used)); 252 if (error) 253 return (error); 254 error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength)); 255 if (error) 256 return (error); 257 error = SYSCTL_OUT(req, &pct, sizeof(pct)); 258 if (error) 259 return (error); 260 return (0); 261 } 262 SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD, 263 0, 0, sysctl_debug_hashstat_nchash, "I", "nchash chain lengths"); 264 265 /* 266 * cache_zap(): 267 * 268 * Removes a namecache entry from cache, whether it contains an actual 269 * pointer to a vnode or if it is just a negative cache entry. 270 */ 271 static void 272 cache_zap(ncp) 273 struct namecache *ncp; 274 { 275 struct vnode *vp; 276 277 mtx_assert(&cache_lock, MA_OWNED); 278 CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp, ncp->nc_vp); 279 vp = NULL; 280 LIST_REMOVE(ncp, nc_hash); 281 LIST_REMOVE(ncp, nc_src); 282 if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) { 283 vp = ncp->nc_dvp; 284 numcachehv--; 285 } 286 if (ncp->nc_vp) { 287 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst); 288 ncp->nc_vp->v_dd = NULL; 289 } else { 290 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 291 numneg--; 292 } 293 numcache--; 294 cache_free(ncp); 295 if (vp) 296 vdrop(vp); 297 } 298 299 /* 300 * Lookup an entry in the cache 301 * 302 * Lookup is called with dvp pointing to the directory to search, 303 * cnp pointing to the name of the entry being sought. If the lookup 304 * succeeds, the vnode is returned in *vpp, and a status of -1 is 305 * returned. If the lookup determines that the name does not exist 306 * (negative cacheing), a status of ENOENT is returned. If the lookup 307 * fails, a status of zero is returned. 308 * 309 * vpp is locked and ref'd on return. If we're looking up DOTDOT, dvp is 310 * unlocked. If we're looking up . an extra ref is taken, but the lock is 311 * not recursively acquired. 312 */ 313 314 int 315 cache_lookup(dvp, vpp, cnp) 316 struct vnode *dvp; 317 struct vnode **vpp; 318 struct componentname *cnp; 319 { 320 struct namecache *ncp; 321 u_int32_t hash; 322 int error, ltype; 323 324 if (!doingcache) { 325 cnp->cn_flags &= ~MAKEENTRY; 326 return (0); 327 } 328 retry: 329 CACHE_LOCK(); 330 numcalls++; 331 332 if (cnp->cn_nameptr[0] == '.') { 333 if (cnp->cn_namelen == 1) { 334 *vpp = dvp; 335 CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .", 336 dvp, cnp->cn_nameptr); 337 dothits++; 338 goto success; 339 } 340 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 341 dotdothits++; 342 if (dvp->v_dd == NULL || 343 (cnp->cn_flags & MAKEENTRY) == 0) { 344 CACHE_UNLOCK(); 345 return (0); 346 } 347 *vpp = dvp->v_dd; 348 CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..", 349 dvp, cnp->cn_nameptr, *vpp); 350 goto success; 351 } 352 } 353 354 hash = fnv_32_buf(cnp->cn_nameptr, cnp->cn_namelen, FNV1_32_INIT); 355 hash = fnv_32_buf(&dvp, sizeof(dvp), hash); 356 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 357 numchecks++; 358 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 359 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 360 break; 361 } 362 363 /* We failed to find an entry */ 364 if (ncp == 0) { 365 if ((cnp->cn_flags & MAKEENTRY) == 0) { 366 nummisszap++; 367 } else { 368 nummiss++; 369 } 370 nchstats.ncs_miss++; 371 CACHE_UNLOCK(); 372 return (0); 373 } 374 375 /* We don't want to have an entry, so dump it */ 376 if ((cnp->cn_flags & MAKEENTRY) == 0) { 377 numposzaps++; 378 nchstats.ncs_badhits++; 379 cache_zap(ncp); 380 CACHE_UNLOCK(); 381 return (0); 382 } 383 384 /* We found a "positive" match, return the vnode */ 385 if (ncp->nc_vp) { 386 numposhits++; 387 nchstats.ncs_goodhits++; 388 *vpp = ncp->nc_vp; 389 CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p", 390 dvp, cnp->cn_nameptr, *vpp, ncp); 391 goto success; 392 } 393 394 /* We found a negative match, and want to create it, so purge */ 395 if (cnp->cn_nameiop == CREATE) { 396 numnegzaps++; 397 nchstats.ncs_badhits++; 398 cache_zap(ncp); 399 CACHE_UNLOCK(); 400 return (0); 401 } 402 403 numneghits++; 404 /* 405 * We found a "negative" match, so we shift it to the end of 406 * the "negative" cache entries queue to satisfy LRU. Also, 407 * check to see if the entry is a whiteout; indicate this to 408 * the componentname, if so. 409 */ 410 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 411 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 412 nchstats.ncs_neghits++; 413 if (ncp->nc_flag & NCF_WHITE) 414 cnp->cn_flags |= ISWHITEOUT; 415 CACHE_UNLOCK(); 416 return (ENOENT); 417 418 success: 419 /* 420 * On success we return a locked and ref'd vnode as per the lookup 421 * protocol. 422 */ 423 if (dvp == *vpp) { /* lookup on "." */ 424 VREF(*vpp); 425 CACHE_UNLOCK(); 426 /* 427 * When we lookup "." we still can be asked to lock it 428 * differently... 429 */ 430 ltype = cnp->cn_lkflags & LK_TYPE_MASK; 431 if (ltype == VOP_ISLOCKED(*vpp)) 432 return (-1); 433 else if (ltype == LK_EXCLUSIVE) 434 vn_lock(*vpp, LK_UPGRADE | LK_RETRY); 435 return (-1); 436 } 437 ltype = 0; /* silence gcc warning */ 438 if (cnp->cn_flags & ISDOTDOT) { 439 ltype = VOP_ISLOCKED(dvp); 440 VOP_UNLOCK(dvp, 0); 441 } 442 VI_LOCK(*vpp); 443 CACHE_UNLOCK(); 444 error = vget(*vpp, cnp->cn_lkflags | LK_INTERLOCK, cnp->cn_thread); 445 if (cnp->cn_flags & ISDOTDOT) 446 vn_lock(dvp, ltype | LK_RETRY); 447 if (error) { 448 *vpp = NULL; 449 goto retry; 450 } 451 if ((cnp->cn_flags & ISLASTCN) && 452 (cnp->cn_lkflags & LK_TYPE_MASK) == LK_EXCLUSIVE) { 453 ASSERT_VOP_ELOCKED(*vpp, "cache_lookup"); 454 } 455 return (-1); 456 } 457 458 /* 459 * Add an entry to the cache. 460 */ 461 void 462 cache_enter(dvp, vp, cnp) 463 struct vnode *dvp; 464 struct vnode *vp; 465 struct componentname *cnp; 466 { 467 struct namecache *ncp; 468 struct nchashhead *ncpp; 469 u_int32_t hash; 470 int hold; 471 int zap; 472 int len; 473 474 CTR3(KTR_VFS, "cache_enter(%p, %p, %s)", dvp, vp, cnp->cn_nameptr); 475 VNASSERT(vp == NULL || (vp->v_iflag & VI_DOOMED) == 0, vp, 476 ("cahe_enter: Adding a doomed vnode")); 477 478 if (!doingcache) 479 return; 480 481 if (cnp->cn_nameptr[0] == '.') { 482 if (cnp->cn_namelen == 1) { 483 return; 484 } 485 /* 486 * For dotdot lookups only cache the v_dd pointer if the 487 * directory has a link back to its parent via v_cache_dst. 488 * Without this an unlinked directory would keep a soft 489 * reference to its parent which could not be NULLd at 490 * cache_purge() time. 491 */ 492 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 493 CACHE_LOCK(); 494 if (!TAILQ_EMPTY(&dvp->v_cache_dst)) 495 dvp->v_dd = vp; 496 CACHE_UNLOCK(); 497 return; 498 } 499 } 500 501 hold = 0; 502 zap = 0; 503 ncp = cache_alloc(cnp->cn_namelen); 504 CACHE_LOCK(); 505 numcache++; 506 if (!vp) { 507 numneg++; 508 ncp->nc_flag = cnp->cn_flags & ISWHITEOUT ? NCF_WHITE : 0; 509 } else if (vp->v_type == VDIR) { 510 vp->v_dd = dvp; 511 } else { 512 vp->v_dd = NULL; 513 } 514 515 /* 516 * Set the rest of the namecache entry elements, calculate it's 517 * hash key and insert it into the appropriate chain within 518 * the cache entries table. 519 */ 520 ncp->nc_vp = vp; 521 ncp->nc_dvp = dvp; 522 len = ncp->nc_nlen = cnp->cn_namelen; 523 hash = fnv_32_buf(cnp->cn_nameptr, len, FNV1_32_INIT); 524 bcopy(cnp->cn_nameptr, ncp->nc_name, len); 525 hash = fnv_32_buf(&dvp, sizeof(dvp), hash); 526 ncpp = NCHHASH(hash); 527 LIST_INSERT_HEAD(ncpp, ncp, nc_hash); 528 if (LIST_EMPTY(&dvp->v_cache_src)) { 529 hold = 1; 530 numcachehv++; 531 } 532 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); 533 /* 534 * If the entry is "negative", we place it into the 535 * "negative" cache queue, otherwise, we place it into the 536 * destination vnode's cache entries queue. 537 */ 538 if (vp) { 539 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); 540 } else { 541 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 542 } 543 if (numneg * ncnegfactor > numcache) { 544 ncp = TAILQ_FIRST(&ncneg); 545 zap = 1; 546 } 547 if (hold) 548 vhold(dvp); 549 if (zap) 550 cache_zap(ncp); 551 CACHE_UNLOCK(); 552 } 553 554 /* 555 * Name cache initialization, from vfs_init() when we are booting 556 */ 557 static void 558 nchinit(void *dummy __unused) 559 { 560 561 TAILQ_INIT(&ncneg); 562 563 cache_zone_small = uma_zcreate("S VFS Cache", CACHE_ZONE_SMALL, NULL, 564 NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 565 cache_zone_large = uma_zcreate("L VFS Cache", CACHE_ZONE_LARGE, NULL, 566 NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 567 568 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash); 569 } 570 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL); 571 572 573 /* 574 * Invalidate all entries to a particular vnode. 575 */ 576 void 577 cache_purge(vp) 578 struct vnode *vp; 579 { 580 581 CTR1(KTR_VFS, "cache_purge(%p)", vp); 582 CACHE_LOCK(); 583 while (!LIST_EMPTY(&vp->v_cache_src)) 584 cache_zap(LIST_FIRST(&vp->v_cache_src)); 585 while (!TAILQ_EMPTY(&vp->v_cache_dst)) 586 cache_zap(TAILQ_FIRST(&vp->v_cache_dst)); 587 vp->v_dd = NULL; 588 CACHE_UNLOCK(); 589 } 590 591 /* 592 * Flush all entries referencing a particular filesystem. 593 */ 594 void 595 cache_purgevfs(mp) 596 struct mount *mp; 597 { 598 struct nchashhead *ncpp; 599 struct namecache *ncp, *nnp; 600 601 /* Scan hash tables for applicable entries */ 602 CACHE_LOCK(); 603 for (ncpp = &nchashtbl[nchash]; ncpp >= nchashtbl; ncpp--) { 604 LIST_FOREACH_SAFE(ncp, ncpp, nc_hash, nnp) { 605 if (ncp->nc_dvp->v_mount == mp) 606 cache_zap(ncp); 607 } 608 } 609 CACHE_UNLOCK(); 610 } 611 612 /* 613 * Perform canonical checks and cache lookup and pass on to filesystem 614 * through the vop_cachedlookup only if needed. 615 */ 616 617 int 618 vfs_cache_lookup(ap) 619 struct vop_lookup_args /* { 620 struct vnode *a_dvp; 621 struct vnode **a_vpp; 622 struct componentname *a_cnp; 623 } */ *ap; 624 { 625 struct vnode *dvp; 626 int error; 627 struct vnode **vpp = ap->a_vpp; 628 struct componentname *cnp = ap->a_cnp; 629 struct ucred *cred = cnp->cn_cred; 630 int flags = cnp->cn_flags; 631 struct thread *td = cnp->cn_thread; 632 633 *vpp = NULL; 634 dvp = ap->a_dvp; 635 636 if (dvp->v_type != VDIR) 637 return (ENOTDIR); 638 639 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && 640 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 641 return (EROFS); 642 643 error = VOP_ACCESS(dvp, VEXEC, cred, td); 644 if (error) 645 return (error); 646 647 error = cache_lookup(dvp, vpp, cnp); 648 if (error == 0) 649 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); 650 if (error == ENOENT) 651 return (error); 652 return (0); 653 } 654 655 656 #ifndef _SYS_SYSPROTO_H_ 657 struct __getcwd_args { 658 u_char *buf; 659 u_int buflen; 660 }; 661 #endif 662 663 /* 664 * XXX All of these sysctls would probably be more productive dead. 665 */ 666 static int disablecwd; 667 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, 668 "Disable the getcwd syscall"); 669 670 /* Implementation of the getcwd syscall. */ 671 int 672 __getcwd(td, uap) 673 struct thread *td; 674 struct __getcwd_args *uap; 675 { 676 677 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen)); 678 } 679 680 int 681 kern___getcwd(struct thread *td, u_char *buf, enum uio_seg bufseg, u_int buflen) 682 { 683 char *bp, *tmpbuf; 684 struct filedesc *fdp; 685 int error; 686 687 if (disablecwd) 688 return (ENODEV); 689 if (buflen < 2) 690 return (EINVAL); 691 if (buflen > MAXPATHLEN) 692 buflen = MAXPATHLEN; 693 694 tmpbuf = malloc(buflen, M_TEMP, M_WAITOK); 695 fdp = td->td_proc->p_fd; 696 FILEDESC_SLOCK(fdp); 697 error = vn_fullpath1(td, fdp->fd_cdir, fdp->fd_rdir, tmpbuf, 698 &bp, buflen); 699 FILEDESC_SUNLOCK(fdp); 700 701 if (!error) { 702 if (bufseg == UIO_SYSSPACE) 703 bcopy(bp, buf, strlen(bp) + 1); 704 else 705 error = copyout(bp, buf, strlen(bp) + 1); 706 } 707 free(tmpbuf, M_TEMP); 708 return (error); 709 } 710 711 /* 712 * Thus begins the fullpath magic. 713 */ 714 715 #undef STATNODE 716 #define STATNODE(name) \ 717 static u_int name; \ 718 SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, "") 719 720 static int disablefullpath; 721 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0, 722 "Disable the vn_fullpath function"); 723 724 /* These count for kern___getcwd(), too. */ 725 STATNODE(numfullpathcalls); 726 STATNODE(numfullpathfail1); 727 STATNODE(numfullpathfail2); 728 STATNODE(numfullpathfail4); 729 STATNODE(numfullpathfound); 730 731 /* 732 * Retrieve the full filesystem path that correspond to a vnode from the name 733 * cache (if available) 734 */ 735 int 736 vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf) 737 { 738 char *buf; 739 struct filedesc *fdp; 740 int error; 741 742 if (disablefullpath) 743 return (ENODEV); 744 if (vn == NULL) 745 return (EINVAL); 746 747 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 748 fdp = td->td_proc->p_fd; 749 FILEDESC_SLOCK(fdp); 750 error = vn_fullpath1(td, vn, fdp->fd_rdir, buf, retbuf, MAXPATHLEN); 751 FILEDESC_SUNLOCK(fdp); 752 753 if (!error) 754 *freebuf = buf; 755 else 756 free(buf, M_TEMP); 757 return (error); 758 } 759 760 /* 761 * This function is similar to vn_fullpath, but it attempts to lookup the 762 * pathname relative to the global root mount point. This is required for the 763 * auditing sub-system, as audited pathnames must be absolute, relative to the 764 * global root mount point. 765 */ 766 int 767 vn_fullpath_global(struct thread *td, struct vnode *vn, 768 char **retbuf, char **freebuf) 769 { 770 char *buf; 771 int error; 772 773 if (disablefullpath) 774 return (ENODEV); 775 if (vn == NULL) 776 return (EINVAL); 777 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 778 error = vn_fullpath1(td, vn, rootvnode, buf, retbuf, MAXPATHLEN); 779 if (!error) 780 *freebuf = buf; 781 else 782 free(buf, M_TEMP); 783 return (error); 784 } 785 786 /* 787 * The magic behind kern___getcwd() and vn_fullpath(). 788 */ 789 static int 790 vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 791 char *buf, char **retbuf, u_int buflen) 792 { 793 char *bp; 794 int error, i, slash_prefixed; 795 struct namecache *ncp; 796 797 bp = buf + buflen - 1; 798 *bp = '\0'; 799 error = 0; 800 slash_prefixed = 0; 801 802 CACHE_LOCK(); 803 numfullpathcalls++; 804 if (vp->v_type != VDIR) { 805 ncp = TAILQ_FIRST(&vp->v_cache_dst); 806 if (!ncp) { 807 numfullpathfail2++; 808 CACHE_UNLOCK(); 809 return (ENOENT); 810 } 811 for (i = ncp->nc_nlen - 1; i >= 0 && bp > buf; i--) 812 *--bp = ncp->nc_name[i]; 813 if (bp == buf) { 814 numfullpathfail4++; 815 CACHE_UNLOCK(); 816 return (ENOMEM); 817 } 818 *--bp = '/'; 819 slash_prefixed = 1; 820 vp = ncp->nc_dvp; 821 } 822 while (vp != rdir && vp != rootvnode) { 823 if (vp->v_vflag & VV_ROOT) { 824 if (vp->v_iflag & VI_DOOMED) { /* forced unmount */ 825 error = EBADF; 826 break; 827 } 828 vp = vp->v_mount->mnt_vnodecovered; 829 continue; 830 } 831 if (vp->v_dd == NULL) { 832 numfullpathfail1++; 833 error = ENOTDIR; 834 break; 835 } 836 ncp = TAILQ_FIRST(&vp->v_cache_dst); 837 if (!ncp) { 838 numfullpathfail2++; 839 error = ENOENT; 840 break; 841 } 842 MPASS(ncp->nc_dvp == vp->v_dd); 843 for (i = ncp->nc_nlen - 1; i >= 0 && bp != buf; i--) 844 *--bp = ncp->nc_name[i]; 845 if (bp == buf) { 846 numfullpathfail4++; 847 error = ENOMEM; 848 break; 849 } 850 *--bp = '/'; 851 slash_prefixed = 1; 852 vp = ncp->nc_dvp; 853 } 854 if (error) { 855 CACHE_UNLOCK(); 856 return (error); 857 } 858 if (!slash_prefixed) { 859 if (bp == buf) { 860 numfullpathfail4++; 861 CACHE_UNLOCK(); 862 return (ENOMEM); 863 } else { 864 *--bp = '/'; 865 } 866 } 867 numfullpathfound++; 868 CACHE_UNLOCK(); 869 870 *retbuf = bp; 871 return (0); 872 } 873 874 int 875 vn_commname(struct vnode *vp, char *buf, u_int buflen) 876 { 877 struct namecache *ncp; 878 int l; 879 880 CACHE_LOCK(); 881 ncp = TAILQ_FIRST(&vp->v_cache_dst); 882 if (!ncp) { 883 CACHE_UNLOCK(); 884 return (ENOENT); 885 } 886 l = min(ncp->nc_nlen, buflen - 1); 887 memcpy(buf, ncp->nc_name, l); 888 CACHE_UNLOCK(); 889 buf[l] = '\0'; 890 return (0); 891 } 892