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 * 3. 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 "opt_ktrace.h" 39 40 #include <sys/param.h> 41 #include <sys/systm.h> 42 #include <sys/counter.h> 43 #include <sys/filedesc.h> 44 #include <sys/fnv_hash.h> 45 #include <sys/kernel.h> 46 #include <sys/lock.h> 47 #include <sys/malloc.h> 48 #include <sys/fcntl.h> 49 #include <sys/mount.h> 50 #include <sys/namei.h> 51 #include <sys/proc.h> 52 #include <sys/rwlock.h> 53 #include <sys/sdt.h> 54 #include <sys/smp.h> 55 #include <sys/syscallsubr.h> 56 #include <sys/sysctl.h> 57 #include <sys/sysproto.h> 58 #include <sys/vnode.h> 59 #ifdef KTRACE 60 #include <sys/ktrace.h> 61 #endif 62 63 #include <vm/uma.h> 64 65 SDT_PROVIDER_DECLARE(vfs); 66 SDT_PROBE_DEFINE3(vfs, namecache, enter, done, "struct vnode *", "char *", 67 "struct vnode *"); 68 SDT_PROBE_DEFINE2(vfs, namecache, enter_negative, done, "struct vnode *", 69 "char *"); 70 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, entry, "struct vnode *"); 71 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, hit, "struct vnode *", 72 "char *", "struct vnode *"); 73 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, miss, "struct vnode *"); 74 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, return, "int", 75 "struct vnode *", "char *"); 76 SDT_PROBE_DEFINE3(vfs, namecache, lookup, hit, "struct vnode *", "char *", 77 "struct vnode *"); 78 SDT_PROBE_DEFINE2(vfs, namecache, lookup, hit__negative, 79 "struct vnode *", "char *"); 80 SDT_PROBE_DEFINE2(vfs, namecache, lookup, miss, "struct vnode *", 81 "char *"); 82 SDT_PROBE_DEFINE1(vfs, namecache, purge, done, "struct vnode *"); 83 SDT_PROBE_DEFINE1(vfs, namecache, purge_negative, done, "struct vnode *"); 84 SDT_PROBE_DEFINE1(vfs, namecache, purgevfs, done, "struct mount *"); 85 SDT_PROBE_DEFINE3(vfs, namecache, zap, done, "struct vnode *", "char *", 86 "struct vnode *"); 87 SDT_PROBE_DEFINE3(vfs, namecache, zap_negative, done, "struct vnode *", 88 "char *", "int"); 89 SDT_PROBE_DEFINE3(vfs, namecache, shrink_negative, done, "struct vnode *", 90 "char *", "int"); 91 92 /* 93 * This structure describes the elements in the cache of recent 94 * names looked up by namei. 95 */ 96 97 struct namecache { 98 LIST_ENTRY(namecache) nc_hash; /* hash chain */ 99 LIST_ENTRY(namecache) nc_src; /* source vnode list */ 100 TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */ 101 struct vnode *nc_dvp; /* vnode of parent of name */ 102 union { 103 struct vnode *nu_vp; /* vnode the name refers to */ 104 u_int nu_neghits; /* negative entry hits */ 105 } n_un; 106 u_char nc_flag; /* flag bits */ 107 u_char nc_nlen; /* length of name */ 108 char nc_name[0]; /* segment name + nul */ 109 }; 110 111 /* 112 * struct namecache_ts repeats struct namecache layout up to the 113 * nc_nlen member. 114 * struct namecache_ts is used in place of struct namecache when time(s) need 115 * to be stored. The nc_dotdottime field is used when a cache entry is mapping 116 * both a non-dotdot directory name plus dotdot for the directory's 117 * parent. 118 */ 119 struct namecache_ts { 120 LIST_ENTRY(namecache) nc_hash; /* hash chain */ 121 LIST_ENTRY(namecache) nc_src; /* source vnode list */ 122 TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */ 123 struct vnode *nc_dvp; /* vnode of parent of name */ 124 union { 125 struct vnode *nu_vp; /* vnode the name refers to */ 126 u_int nu_neghits; /* negative entry hits */ 127 } n_un; 128 u_char nc_flag; /* flag bits */ 129 u_char nc_nlen; /* length of name */ 130 struct timespec nc_time; /* timespec provided by fs */ 131 struct timespec nc_dotdottime; /* dotdot timespec provided by fs */ 132 int nc_ticks; /* ticks value when entry was added */ 133 char nc_name[0]; /* segment name + nul */ 134 }; 135 136 #define nc_vp n_un.nu_vp 137 #define nc_neghits n_un.nu_neghits 138 139 /* 140 * Flags in namecache.nc_flag 141 */ 142 #define NCF_WHITE 0x01 143 #define NCF_ISDOTDOT 0x02 144 #define NCF_TS 0x04 145 #define NCF_DTS 0x08 146 #define NCF_DVDROP 0x10 147 #define NCF_NEGATIVE 0x20 148 #define NCF_HOTNEGATIVE 0x40 149 150 /* 151 * Name caching works as follows: 152 * 153 * Names found by directory scans are retained in a cache 154 * for future reference. It is managed LRU, so frequently 155 * used names will hang around. Cache is indexed by hash value 156 * obtained from (vp, name) where vp refers to the directory 157 * containing name. 158 * 159 * If it is a "negative" entry, (i.e. for a name that is known NOT to 160 * exist) the vnode pointer will be NULL. 161 * 162 * Upon reaching the last segment of a path, if the reference 163 * is for DELETE, or NOCACHE is set (rewrite), and the 164 * name is located in the cache, it will be dropped. 165 * 166 * These locks are used (in the order in which they can be taken): 167 * NAME TYPE ROLE 168 * vnodelock mtx vnode lists and v_cache_dd field protection 169 * bucketlock rwlock for access to given set of hash buckets 170 * neglist mtx negative entry LRU management 171 * 172 * Additionally, ncneg_shrink_lock mtx is used to have at most one thread 173 * shrinking the LRU list. 174 * 175 * It is legal to take multiple vnodelock and bucketlock locks. The locking 176 * order is lower address first. Both are recursive. 177 * 178 * "." lookups are lockless. 179 * 180 * ".." and vnode -> name lookups require vnodelock. 181 * 182 * name -> vnode lookup requires the relevant bucketlock to be held for reading. 183 * 184 * Insertions and removals of entries require involved vnodes and bucketlocks 185 * to be write-locked to prevent other threads from seeing the entry. 186 * 187 * Some lookups result in removal of the found entry (e.g. getting rid of a 188 * negative entry with the intent to create a positive one), which poses a 189 * problem when multiple threads reach the state. Similarly, two different 190 * threads can purge two different vnodes and try to remove the same name. 191 * 192 * If the already held vnode lock is lower than the second required lock, we 193 * can just take the other lock. However, in the opposite case, this could 194 * deadlock. As such, this is resolved by trylocking and if that fails unlocking 195 * the first node, locking everything in order and revalidating the state. 196 */ 197 198 /* 199 * Structures associated with name caching. 200 */ 201 #define NCHHASH(hash) \ 202 (&nchashtbl[(hash) & nchash]) 203 static LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */ 204 static u_long nchash; /* size of hash table */ 205 SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, 206 "Size of namecache hash table"); 207 static u_long ncnegfactor = 16; /* ratio of negative entries */ 208 SYSCTL_ULONG(_vfs, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, 209 "Ratio of negative namecache entries"); 210 static u_long numneg; /* number of negative entries allocated */ 211 SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, 212 "Number of negative entries in namecache"); 213 static u_long numcache; /* number of cache entries allocated */ 214 SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, 215 "Number of namecache entries"); 216 static u_long numcachehv; /* number of cache entries with vnodes held */ 217 SYSCTL_ULONG(_debug, OID_AUTO, numcachehv, CTLFLAG_RD, &numcachehv, 0, 218 "Number of namecache entries with vnodes held"); 219 u_int ncsizefactor = 2; 220 SYSCTL_UINT(_vfs, OID_AUTO, ncsizefactor, CTLFLAG_RW, &ncsizefactor, 0, 221 "Size factor for namecache"); 222 static u_int ncpurgeminvnodes; 223 SYSCTL_UINT(_vfs, OID_AUTO, ncpurgeminvnodes, CTLFLAG_RW, &ncpurgeminvnodes, 0, 224 "Number of vnodes below which purgevfs ignores the request"); 225 static u_int ncneghitsrequeue = 8; 226 SYSCTL_UINT(_vfs, OID_AUTO, ncneghitsrequeue, CTLFLAG_RW, &ncneghitsrequeue, 0, 227 "Number of hits to requeue a negative entry in the LRU list"); 228 229 struct nchstats nchstats; /* cache effectiveness statistics */ 230 231 static struct mtx ncneg_shrink_lock; 232 233 struct neglist { 234 struct mtx nl_lock; 235 TAILQ_HEAD(, namecache) nl_list; 236 } __aligned(CACHE_LINE_SIZE); 237 238 static struct neglist *neglists; 239 static struct neglist ncneg_hot; 240 241 static int shrink_list_turn; 242 243 #define numneglists (ncneghash + 1) 244 static u_int ncneghash; 245 static inline struct neglist * 246 NCP2NEGLIST(struct namecache *ncp) 247 { 248 249 return (&neglists[(((uintptr_t)(ncp) >> 8) & ncneghash)]); 250 } 251 252 #define numbucketlocks (ncbuckethash + 1) 253 static u_int ncbuckethash; 254 static struct rwlock_padalign *bucketlocks; 255 #define HASH2BUCKETLOCK(hash) \ 256 ((struct rwlock *)(&bucketlocks[((hash) & ncbuckethash)])) 257 258 #define numvnodelocks (ncvnodehash + 1) 259 static u_int ncvnodehash; 260 static struct mtx *vnodelocks; 261 static inline struct mtx * 262 VP2VNODELOCK(struct vnode *vp) 263 { 264 265 return (&vnodelocks[(((uintptr_t)(vp) >> 8) & ncvnodehash)]); 266 } 267 268 /* 269 * UMA zones for the VFS cache. 270 * 271 * The small cache is used for entries with short names, which are the 272 * most common. The large cache is used for entries which are too big to 273 * fit in the small cache. 274 */ 275 static uma_zone_t cache_zone_small; 276 static uma_zone_t cache_zone_small_ts; 277 static uma_zone_t cache_zone_large; 278 static uma_zone_t cache_zone_large_ts; 279 280 #define CACHE_PATH_CUTOFF 35 281 282 static struct namecache * 283 cache_alloc(int len, int ts) 284 { 285 286 if (len > CACHE_PATH_CUTOFF) { 287 if (ts) 288 return (uma_zalloc(cache_zone_large_ts, M_WAITOK)); 289 else 290 return (uma_zalloc(cache_zone_large, M_WAITOK)); 291 } 292 if (ts) 293 return (uma_zalloc(cache_zone_small_ts, M_WAITOK)); 294 else 295 return (uma_zalloc(cache_zone_small, M_WAITOK)); 296 } 297 298 static void 299 cache_free(struct namecache *ncp) 300 { 301 int ts; 302 303 if (ncp == NULL) 304 return; 305 ts = ncp->nc_flag & NCF_TS; 306 if ((ncp->nc_flag & NCF_DVDROP) != 0) 307 vdrop(ncp->nc_dvp); 308 if (ncp->nc_nlen <= CACHE_PATH_CUTOFF) { 309 if (ts) 310 uma_zfree(cache_zone_small_ts, ncp); 311 else 312 uma_zfree(cache_zone_small, ncp); 313 } else if (ts) 314 uma_zfree(cache_zone_large_ts, ncp); 315 else 316 uma_zfree(cache_zone_large, ncp); 317 } 318 319 static char * 320 nc_get_name(struct namecache *ncp) 321 { 322 struct namecache_ts *ncp_ts; 323 324 if ((ncp->nc_flag & NCF_TS) == 0) 325 return (ncp->nc_name); 326 ncp_ts = (struct namecache_ts *)ncp; 327 return (ncp_ts->nc_name); 328 } 329 330 static void 331 cache_out_ts(struct namecache *ncp, struct timespec *tsp, int *ticksp) 332 { 333 334 KASSERT((ncp->nc_flag & NCF_TS) != 0 || 335 (tsp == NULL && ticksp == NULL), 336 ("No NCF_TS")); 337 338 if (tsp != NULL) 339 *tsp = ((struct namecache_ts *)ncp)->nc_time; 340 if (ticksp != NULL) 341 *ticksp = ((struct namecache_ts *)ncp)->nc_ticks; 342 } 343 344 static int doingcache = 1; /* 1 => enable the cache */ 345 SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0, 346 "VFS namecache enabled"); 347 348 /* Export size information to userland */ 349 SYSCTL_INT(_debug_sizeof, OID_AUTO, namecache, CTLFLAG_RD, SYSCTL_NULL_INT_PTR, 350 sizeof(struct namecache), "sizeof(struct namecache)"); 351 352 /* 353 * The new name cache statistics 354 */ 355 static SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, 356 "Name cache statistics"); 357 #define STATNODE_ULONG(name, descr) \ 358 SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, descr); 359 #define STATNODE_COUNTER(name, descr) \ 360 static counter_u64_t name; \ 361 SYSCTL_COUNTER_U64(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, descr); 362 STATNODE_ULONG(numneg, "Number of negative cache entries"); 363 STATNODE_ULONG(numcache, "Number of cache entries"); 364 STATNODE_COUNTER(numcalls, "Number of cache lookups"); 365 STATNODE_COUNTER(dothits, "Number of '.' hits"); 366 STATNODE_COUNTER(dotdothits, "Number of '..' hits"); 367 STATNODE_COUNTER(numchecks, "Number of checks in lookup"); 368 STATNODE_COUNTER(nummiss, "Number of cache misses"); 369 STATNODE_COUNTER(nummisszap, "Number of cache misses we do not want to cache"); 370 STATNODE_COUNTER(numposzaps, 371 "Number of cache hits (positive) we do not want to cache"); 372 STATNODE_COUNTER(numposhits, "Number of cache hits (positive)"); 373 STATNODE_COUNTER(numnegzaps, 374 "Number of cache hits (negative) we do not want to cache"); 375 STATNODE_COUNTER(numneghits, "Number of cache hits (negative)"); 376 /* These count for kern___getcwd(), too. */ 377 STATNODE_COUNTER(numfullpathcalls, "Number of fullpath search calls"); 378 STATNODE_COUNTER(numfullpathfail1, "Number of fullpath search errors (ENOTDIR)"); 379 STATNODE_COUNTER(numfullpathfail2, 380 "Number of fullpath search errors (VOP_VPTOCNP failures)"); 381 STATNODE_COUNTER(numfullpathfail4, "Number of fullpath search errors (ENOMEM)"); 382 STATNODE_COUNTER(numfullpathfound, "Number of successful fullpath calls"); 383 static long zap_and_exit_bucket_fail; STATNODE_ULONG(zap_and_exit_bucket_fail, 384 "Number of times zap_and_exit failed to lock"); 385 static long cache_lock_vnodes_cel_3_failures; 386 STATNODE_ULONG(cache_lock_vnodes_cel_3_failures, 387 "Number of times 3-way vnode locking failed"); 388 389 static void cache_zap_locked(struct namecache *ncp, bool neg_locked); 390 static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 391 char *buf, char **retbuf, u_int buflen); 392 393 static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); 394 395 static int cache_yield; 396 SYSCTL_INT(_vfs_cache, OID_AUTO, yield, CTLFLAG_RD, &cache_yield, 0, 397 "Number of times cache called yield"); 398 399 static void 400 cache_maybe_yield(void) 401 { 402 403 if (should_yield()) { 404 cache_yield++; 405 kern_yield(PRI_USER); 406 } 407 } 408 409 static inline void 410 cache_assert_vlp_locked(struct mtx *vlp) 411 { 412 413 if (vlp != NULL) 414 mtx_assert(vlp, MA_OWNED); 415 } 416 417 static inline void 418 cache_assert_vnode_locked(struct vnode *vp) 419 { 420 struct mtx *vlp; 421 422 vlp = VP2VNODELOCK(vp); 423 cache_assert_vlp_locked(vlp); 424 } 425 426 static uint32_t 427 cache_get_hash(char *name, u_char len, struct vnode *dvp) 428 { 429 uint32_t hash; 430 431 hash = fnv_32_buf(name, len, FNV1_32_INIT); 432 hash = fnv_32_buf(&dvp, sizeof(dvp), hash); 433 return (hash); 434 } 435 436 static inline struct rwlock * 437 NCP2BUCKETLOCK(struct namecache *ncp) 438 { 439 uint32_t hash; 440 441 hash = cache_get_hash(nc_get_name(ncp), ncp->nc_nlen, ncp->nc_dvp); 442 return (HASH2BUCKETLOCK(hash)); 443 } 444 445 #ifdef INVARIANTS 446 static void 447 cache_assert_bucket_locked(struct namecache *ncp, int mode) 448 { 449 struct rwlock *blp; 450 451 blp = NCP2BUCKETLOCK(ncp); 452 rw_assert(blp, mode); 453 } 454 #else 455 #define cache_assert_bucket_locked(x, y) do { } while (0) 456 #endif 457 458 #define cache_sort(x, y) _cache_sort((void **)(x), (void **)(y)) 459 static void 460 _cache_sort(void **p1, void **p2) 461 { 462 void *tmp; 463 464 if (*p1 > *p2) { 465 tmp = *p2; 466 *p2 = *p1; 467 *p1 = tmp; 468 } 469 } 470 471 static void 472 cache_lock_all_buckets(void) 473 { 474 u_int i; 475 476 for (i = 0; i < numbucketlocks; i++) 477 rw_wlock(&bucketlocks[i]); 478 } 479 480 static void 481 cache_unlock_all_buckets(void) 482 { 483 u_int i; 484 485 for (i = 0; i < numbucketlocks; i++) 486 rw_wunlock(&bucketlocks[i]); 487 } 488 489 static void 490 cache_lock_all_vnodes(void) 491 { 492 u_int i; 493 494 for (i = 0; i < numvnodelocks; i++) 495 mtx_lock(&vnodelocks[i]); 496 } 497 498 static void 499 cache_unlock_all_vnodes(void) 500 { 501 u_int i; 502 503 for (i = 0; i < numvnodelocks; i++) 504 mtx_unlock(&vnodelocks[i]); 505 } 506 507 static int 508 cache_trylock_vnodes(struct mtx *vlp1, struct mtx *vlp2) 509 { 510 511 cache_sort(&vlp1, &vlp2); 512 MPASS(vlp2 != NULL); 513 514 if (vlp1 != NULL) { 515 if (!mtx_trylock(vlp1)) 516 return (EAGAIN); 517 } 518 if (!mtx_trylock(vlp2)) { 519 if (vlp1 != NULL) 520 mtx_unlock(vlp1); 521 return (EAGAIN); 522 } 523 524 return (0); 525 } 526 527 static void 528 cache_unlock_vnodes(struct mtx *vlp1, struct mtx *vlp2) 529 { 530 531 MPASS(vlp1 != NULL || vlp2 != NULL); 532 533 if (vlp1 != NULL) 534 mtx_unlock(vlp1); 535 if (vlp2 != NULL) 536 mtx_unlock(vlp2); 537 } 538 539 static int 540 sysctl_nchstats(SYSCTL_HANDLER_ARGS) 541 { 542 struct nchstats snap; 543 544 if (req->oldptr == NULL) 545 return (SYSCTL_OUT(req, 0, sizeof(snap))); 546 547 snap = nchstats; 548 snap.ncs_goodhits = counter_u64_fetch(numposhits); 549 snap.ncs_neghits = counter_u64_fetch(numneghits); 550 snap.ncs_badhits = counter_u64_fetch(numposzaps) + 551 counter_u64_fetch(numnegzaps); 552 snap.ncs_miss = counter_u64_fetch(nummisszap) + 553 counter_u64_fetch(nummiss); 554 555 return (SYSCTL_OUT(req, &snap, sizeof(snap))); 556 } 557 SYSCTL_PROC(_vfs_cache, OID_AUTO, nchstats, CTLTYPE_OPAQUE | CTLFLAG_RD | 558 CTLFLAG_MPSAFE, 0, 0, sysctl_nchstats, "LU", 559 "VFS cache effectiveness statistics"); 560 561 #ifdef DIAGNOSTIC 562 /* 563 * Grab an atomic snapshot of the name cache hash chain lengths 564 */ 565 static SYSCTL_NODE(_debug, OID_AUTO, hashstat, CTLFLAG_RW, NULL, 566 "hash table stats"); 567 568 static int 569 sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS) 570 { 571 struct nchashhead *ncpp; 572 struct namecache *ncp; 573 int i, error, n_nchash, *cntbuf; 574 575 retry: 576 n_nchash = nchash + 1; /* nchash is max index, not count */ 577 if (req->oldptr == NULL) 578 return SYSCTL_OUT(req, 0, n_nchash * sizeof(int)); 579 cntbuf = malloc(n_nchash * sizeof(int), M_TEMP, M_ZERO | M_WAITOK); 580 cache_lock_all_buckets(); 581 if (n_nchash != nchash + 1) { 582 cache_unlock_all_buckets(); 583 free(cntbuf, M_TEMP); 584 goto retry; 585 } 586 /* Scan hash tables counting entries */ 587 for (ncpp = nchashtbl, i = 0; i < n_nchash; ncpp++, i++) 588 LIST_FOREACH(ncp, ncpp, nc_hash) 589 cntbuf[i]++; 590 cache_unlock_all_buckets(); 591 for (error = 0, i = 0; i < n_nchash; i++) 592 if ((error = SYSCTL_OUT(req, &cntbuf[i], sizeof(int))) != 0) 593 break; 594 free(cntbuf, M_TEMP); 595 return (error); 596 } 597 SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD| 598 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_rawnchash, "S,int", 599 "nchash chain lengths"); 600 601 static int 602 sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS) 603 { 604 int error; 605 struct nchashhead *ncpp; 606 struct namecache *ncp; 607 int n_nchash; 608 int count, maxlength, used, pct; 609 610 if (!req->oldptr) 611 return SYSCTL_OUT(req, 0, 4 * sizeof(int)); 612 613 cache_lock_all_buckets(); 614 n_nchash = nchash + 1; /* nchash is max index, not count */ 615 used = 0; 616 maxlength = 0; 617 618 /* Scan hash tables for applicable entries */ 619 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { 620 count = 0; 621 LIST_FOREACH(ncp, ncpp, nc_hash) { 622 count++; 623 } 624 if (count) 625 used++; 626 if (maxlength < count) 627 maxlength = count; 628 } 629 n_nchash = nchash + 1; 630 cache_unlock_all_buckets(); 631 pct = (used * 100) / (n_nchash / 100); 632 error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash)); 633 if (error) 634 return (error); 635 error = SYSCTL_OUT(req, &used, sizeof(used)); 636 if (error) 637 return (error); 638 error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength)); 639 if (error) 640 return (error); 641 error = SYSCTL_OUT(req, &pct, sizeof(pct)); 642 if (error) 643 return (error); 644 return (0); 645 } 646 SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD| 647 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_nchash, "I", 648 "nchash statistics (number of total/used buckets, maximum chain length, usage percentage)"); 649 #endif 650 651 /* 652 * Negative entries management 653 * 654 * A variation of LRU scheme is used. New entries are hashed into one of 655 * numneglists cold lists. Entries get promoted to the hot list on first hit. 656 * Partial LRU for the hot list is maintained by requeueing them every 657 * ncneghitsrequeue hits. 658 * 659 * The shrinker will demote hot list head and evict from the cold list in a 660 * round-robin manner. 661 */ 662 static void 663 cache_negative_hit(struct namecache *ncp) 664 { 665 struct neglist *neglist; 666 u_int hits; 667 668 MPASS(ncp->nc_flag & NCF_NEGATIVE); 669 hits = atomic_fetchadd_int(&ncp->nc_neghits, 1); 670 if (ncp->nc_flag & NCF_HOTNEGATIVE) { 671 if ((hits % ncneghitsrequeue) != 0) 672 return; 673 mtx_lock(&ncneg_hot.nl_lock); 674 if (ncp->nc_flag & NCF_HOTNEGATIVE) { 675 TAILQ_REMOVE(&ncneg_hot.nl_list, ncp, nc_dst); 676 TAILQ_INSERT_TAIL(&ncneg_hot.nl_list, ncp, nc_dst); 677 mtx_unlock(&ncneg_hot.nl_lock); 678 return; 679 } 680 /* 681 * The shrinker cleared the flag and removed the entry from 682 * the hot list. Put it back. 683 */ 684 } else { 685 mtx_lock(&ncneg_hot.nl_lock); 686 } 687 neglist = NCP2NEGLIST(ncp); 688 mtx_lock(&neglist->nl_lock); 689 if (!(ncp->nc_flag & NCF_HOTNEGATIVE)) { 690 TAILQ_REMOVE(&neglist->nl_list, ncp, nc_dst); 691 TAILQ_INSERT_TAIL(&ncneg_hot.nl_list, ncp, nc_dst); 692 ncp->nc_flag |= NCF_HOTNEGATIVE; 693 } 694 mtx_unlock(&neglist->nl_lock); 695 mtx_unlock(&ncneg_hot.nl_lock); 696 } 697 698 static void 699 cache_negative_insert(struct namecache *ncp, bool neg_locked) 700 { 701 struct neglist *neglist; 702 703 MPASS(ncp->nc_flag & NCF_NEGATIVE); 704 cache_assert_bucket_locked(ncp, RA_WLOCKED); 705 neglist = NCP2NEGLIST(ncp); 706 if (!neg_locked) { 707 mtx_lock(&neglist->nl_lock); 708 } else { 709 mtx_assert(&neglist->nl_lock, MA_OWNED); 710 } 711 TAILQ_INSERT_TAIL(&neglist->nl_list, ncp, nc_dst); 712 if (!neg_locked) 713 mtx_unlock(&neglist->nl_lock); 714 atomic_add_rel_long(&numneg, 1); 715 } 716 717 static void 718 cache_negative_remove(struct namecache *ncp, bool neg_locked) 719 { 720 struct neglist *neglist; 721 bool hot_locked = false; 722 bool list_locked = false; 723 724 MPASS(ncp->nc_flag & NCF_NEGATIVE); 725 cache_assert_bucket_locked(ncp, RA_WLOCKED); 726 neglist = NCP2NEGLIST(ncp); 727 if (!neg_locked) { 728 if (ncp->nc_flag & NCF_HOTNEGATIVE) { 729 hot_locked = true; 730 mtx_lock(&ncneg_hot.nl_lock); 731 if (!(ncp->nc_flag & NCF_HOTNEGATIVE)) { 732 list_locked = true; 733 mtx_lock(&neglist->nl_lock); 734 } 735 } else { 736 list_locked = true; 737 mtx_lock(&neglist->nl_lock); 738 } 739 } else { 740 mtx_assert(&neglist->nl_lock, MA_OWNED); 741 mtx_assert(&ncneg_hot.nl_lock, MA_OWNED); 742 } 743 if (ncp->nc_flag & NCF_HOTNEGATIVE) { 744 TAILQ_REMOVE(&ncneg_hot.nl_list, ncp, nc_dst); 745 } else { 746 TAILQ_REMOVE(&neglist->nl_list, ncp, nc_dst); 747 } 748 if (list_locked) 749 mtx_unlock(&neglist->nl_lock); 750 if (hot_locked) 751 mtx_unlock(&ncneg_hot.nl_lock); 752 atomic_subtract_rel_long(&numneg, 1); 753 } 754 755 static void 756 cache_negative_shrink_select(int start, struct namecache **ncpp, 757 struct neglist **neglistpp) 758 { 759 struct neglist *neglist; 760 struct namecache *ncp; 761 int i; 762 763 *ncpp = ncp = NULL; 764 765 for (i = start; i < numneglists; i++) { 766 neglist = &neglists[i]; 767 if (TAILQ_FIRST(&neglist->nl_list) == NULL) 768 continue; 769 mtx_lock(&neglist->nl_lock); 770 ncp = TAILQ_FIRST(&neglist->nl_list); 771 if (ncp != NULL) 772 break; 773 mtx_unlock(&neglist->nl_lock); 774 } 775 776 *neglistpp = neglist; 777 *ncpp = ncp; 778 } 779 780 static void 781 cache_negative_zap_one(void) 782 { 783 struct namecache *ncp, *ncp2; 784 struct neglist *neglist; 785 struct mtx *dvlp; 786 struct rwlock *blp; 787 788 if (!mtx_trylock(&ncneg_shrink_lock)) 789 return; 790 791 mtx_lock(&ncneg_hot.nl_lock); 792 ncp = TAILQ_FIRST(&ncneg_hot.nl_list); 793 if (ncp != NULL) { 794 neglist = NCP2NEGLIST(ncp); 795 mtx_lock(&neglist->nl_lock); 796 TAILQ_REMOVE(&ncneg_hot.nl_list, ncp, nc_dst); 797 TAILQ_INSERT_TAIL(&neglist->nl_list, ncp, nc_dst); 798 ncp->nc_flag &= ~NCF_HOTNEGATIVE; 799 mtx_unlock(&neglist->nl_lock); 800 } 801 802 cache_negative_shrink_select(shrink_list_turn, &ncp, &neglist); 803 shrink_list_turn++; 804 if (shrink_list_turn == numneglists) 805 shrink_list_turn = 0; 806 if (ncp == NULL && shrink_list_turn == 0) 807 cache_negative_shrink_select(shrink_list_turn, &ncp, &neglist); 808 if (ncp == NULL) { 809 mtx_unlock(&ncneg_hot.nl_lock); 810 goto out; 811 } 812 813 MPASS(ncp->nc_flag & NCF_NEGATIVE); 814 dvlp = VP2VNODELOCK(ncp->nc_dvp); 815 blp = NCP2BUCKETLOCK(ncp); 816 mtx_unlock(&neglist->nl_lock); 817 mtx_unlock(&ncneg_hot.nl_lock); 818 mtx_lock(dvlp); 819 rw_wlock(blp); 820 mtx_lock(&ncneg_hot.nl_lock); 821 mtx_lock(&neglist->nl_lock); 822 ncp2 = TAILQ_FIRST(&neglist->nl_list); 823 if (ncp != ncp2 || dvlp != VP2VNODELOCK(ncp2->nc_dvp) || 824 blp != NCP2BUCKETLOCK(ncp2) || !(ncp2->nc_flag & NCF_NEGATIVE)) { 825 ncp = NULL; 826 goto out_unlock_all; 827 } 828 SDT_PROBE3(vfs, namecache, shrink_negative, done, ncp->nc_dvp, 829 nc_get_name(ncp), ncp->nc_neghits); 830 831 cache_zap_locked(ncp, true); 832 out_unlock_all: 833 mtx_unlock(&neglist->nl_lock); 834 mtx_unlock(&ncneg_hot.nl_lock); 835 rw_wunlock(blp); 836 mtx_unlock(dvlp); 837 out: 838 mtx_unlock(&ncneg_shrink_lock); 839 cache_free(ncp); 840 } 841 842 /* 843 * cache_zap_locked(): 844 * 845 * Removes a namecache entry from cache, whether it contains an actual 846 * pointer to a vnode or if it is just a negative cache entry. 847 */ 848 static void 849 cache_zap_locked(struct namecache *ncp, bool neg_locked) 850 { 851 852 if (!(ncp->nc_flag & NCF_NEGATIVE)) 853 cache_assert_vnode_locked(ncp->nc_vp); 854 cache_assert_vnode_locked(ncp->nc_dvp); 855 cache_assert_bucket_locked(ncp, RA_WLOCKED); 856 857 CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp, 858 (ncp->nc_flag & NCF_NEGATIVE) ? NULL : ncp->nc_vp); 859 if (!(ncp->nc_flag & NCF_NEGATIVE)) { 860 SDT_PROBE3(vfs, namecache, zap, done, ncp->nc_dvp, 861 nc_get_name(ncp), ncp->nc_vp); 862 } else { 863 SDT_PROBE3(vfs, namecache, zap_negative, done, ncp->nc_dvp, 864 nc_get_name(ncp), ncp->nc_neghits); 865 } 866 LIST_REMOVE(ncp, nc_hash); 867 if (!(ncp->nc_flag & NCF_NEGATIVE)) { 868 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst); 869 if (ncp == ncp->nc_vp->v_cache_dd) 870 ncp->nc_vp->v_cache_dd = NULL; 871 } else { 872 cache_negative_remove(ncp, neg_locked); 873 } 874 if (ncp->nc_flag & NCF_ISDOTDOT) { 875 if (ncp == ncp->nc_dvp->v_cache_dd) 876 ncp->nc_dvp->v_cache_dd = NULL; 877 } else { 878 LIST_REMOVE(ncp, nc_src); 879 if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) { 880 ncp->nc_flag |= NCF_DVDROP; 881 atomic_subtract_rel_long(&numcachehv, 1); 882 } 883 } 884 atomic_subtract_rel_long(&numcache, 1); 885 } 886 887 static void 888 cache_zap_negative_locked_vnode_kl(struct namecache *ncp, struct vnode *vp) 889 { 890 struct rwlock *blp; 891 892 MPASS(ncp->nc_dvp == vp); 893 MPASS(ncp->nc_flag & NCF_NEGATIVE); 894 cache_assert_vnode_locked(vp); 895 896 blp = NCP2BUCKETLOCK(ncp); 897 rw_wlock(blp); 898 cache_zap_locked(ncp, false); 899 rw_wunlock(blp); 900 } 901 902 static bool 903 cache_zap_locked_vnode_kl2(struct namecache *ncp, struct vnode *vp, 904 struct mtx **vlpp) 905 { 906 struct mtx *pvlp, *vlp1, *vlp2, *to_unlock; 907 struct rwlock *blp; 908 909 MPASS(vp == ncp->nc_dvp || vp == ncp->nc_vp); 910 cache_assert_vnode_locked(vp); 911 912 if (ncp->nc_flag & NCF_NEGATIVE) { 913 if (*vlpp != NULL) { 914 mtx_unlock(*vlpp); 915 *vlpp = NULL; 916 } 917 cache_zap_negative_locked_vnode_kl(ncp, vp); 918 return (true); 919 } 920 921 pvlp = VP2VNODELOCK(vp); 922 blp = NCP2BUCKETLOCK(ncp); 923 vlp1 = VP2VNODELOCK(ncp->nc_dvp); 924 vlp2 = VP2VNODELOCK(ncp->nc_vp); 925 926 if (*vlpp == vlp1 || *vlpp == vlp2) { 927 to_unlock = *vlpp; 928 *vlpp = NULL; 929 } else { 930 if (*vlpp != NULL) { 931 mtx_unlock(*vlpp); 932 *vlpp = NULL; 933 } 934 cache_sort(&vlp1, &vlp2); 935 if (vlp1 == pvlp) { 936 mtx_lock(vlp2); 937 to_unlock = vlp2; 938 } else { 939 if (!mtx_trylock(vlp1)) 940 goto out_relock; 941 to_unlock = vlp1; 942 } 943 } 944 rw_wlock(blp); 945 cache_zap_locked(ncp, false); 946 rw_wunlock(blp); 947 if (to_unlock != NULL) 948 mtx_unlock(to_unlock); 949 return (true); 950 951 out_relock: 952 mtx_unlock(vlp2); 953 mtx_lock(vlp1); 954 mtx_lock(vlp2); 955 MPASS(*vlpp == NULL); 956 *vlpp = vlp1; 957 return (false); 958 } 959 960 static int 961 cache_zap_locked_vnode(struct namecache *ncp, struct vnode *vp) 962 { 963 struct mtx *pvlp, *vlp1, *vlp2, *to_unlock; 964 struct rwlock *blp; 965 int error = 0; 966 967 MPASS(vp == ncp->nc_dvp || vp == ncp->nc_vp); 968 cache_assert_vnode_locked(vp); 969 970 pvlp = VP2VNODELOCK(vp); 971 if (ncp->nc_flag & NCF_NEGATIVE) { 972 cache_zap_negative_locked_vnode_kl(ncp, vp); 973 goto out; 974 } 975 976 blp = NCP2BUCKETLOCK(ncp); 977 vlp1 = VP2VNODELOCK(ncp->nc_dvp); 978 vlp2 = VP2VNODELOCK(ncp->nc_vp); 979 cache_sort(&vlp1, &vlp2); 980 if (vlp1 == pvlp) { 981 mtx_lock(vlp2); 982 to_unlock = vlp2; 983 } else { 984 if (!mtx_trylock(vlp1)) { 985 error = EAGAIN; 986 goto out; 987 } 988 to_unlock = vlp1; 989 } 990 rw_wlock(blp); 991 cache_zap_locked(ncp, false); 992 rw_wunlock(blp); 993 mtx_unlock(to_unlock); 994 out: 995 mtx_unlock(pvlp); 996 return (error); 997 } 998 999 static int 1000 cache_zap_rlocked_bucket(struct namecache *ncp, struct rwlock *blp) 1001 { 1002 struct mtx *dvlp, *vlp; 1003 1004 cache_assert_bucket_locked(ncp, RA_RLOCKED); 1005 1006 dvlp = VP2VNODELOCK(ncp->nc_dvp); 1007 vlp = NULL; 1008 if (!(ncp->nc_flag & NCF_NEGATIVE)) 1009 vlp = VP2VNODELOCK(ncp->nc_vp); 1010 if (cache_trylock_vnodes(dvlp, vlp) == 0) { 1011 rw_runlock(blp); 1012 rw_wlock(blp); 1013 cache_zap_locked(ncp, false); 1014 rw_wunlock(blp); 1015 cache_unlock_vnodes(dvlp, vlp); 1016 return (0); 1017 } 1018 1019 rw_runlock(blp); 1020 return (EAGAIN); 1021 } 1022 1023 static int 1024 cache_zap_wlocked_bucket_kl(struct namecache *ncp, struct rwlock *blp, 1025 struct mtx **vlpp1, struct mtx **vlpp2) 1026 { 1027 struct mtx *dvlp, *vlp; 1028 1029 cache_assert_bucket_locked(ncp, RA_WLOCKED); 1030 1031 dvlp = VP2VNODELOCK(ncp->nc_dvp); 1032 vlp = NULL; 1033 if (!(ncp->nc_flag & NCF_NEGATIVE)) 1034 vlp = VP2VNODELOCK(ncp->nc_vp); 1035 cache_sort(&dvlp, &vlp); 1036 1037 if (*vlpp1 == dvlp && *vlpp2 == vlp) { 1038 cache_zap_locked(ncp, false); 1039 cache_unlock_vnodes(dvlp, vlp); 1040 *vlpp1 = NULL; 1041 *vlpp2 = NULL; 1042 return (0); 1043 } 1044 1045 if (*vlpp1 != NULL) 1046 mtx_unlock(*vlpp1); 1047 if (*vlpp2 != NULL) 1048 mtx_unlock(*vlpp2); 1049 *vlpp1 = NULL; 1050 *vlpp2 = NULL; 1051 1052 if (cache_trylock_vnodes(dvlp, vlp) == 0) { 1053 cache_zap_locked(ncp, false); 1054 cache_unlock_vnodes(dvlp, vlp); 1055 return (0); 1056 } 1057 1058 rw_wunlock(blp); 1059 *vlpp1 = dvlp; 1060 *vlpp2 = vlp; 1061 if (*vlpp1 != NULL) 1062 mtx_lock(*vlpp1); 1063 mtx_lock(*vlpp2); 1064 rw_wlock(blp); 1065 return (EAGAIN); 1066 } 1067 1068 static void 1069 cache_lookup_unlock(struct rwlock *blp, struct mtx *vlp) 1070 { 1071 1072 if (blp != NULL) { 1073 rw_runlock(blp); 1074 mtx_assert(vlp, MA_NOTOWNED); 1075 } else { 1076 mtx_unlock(vlp); 1077 } 1078 } 1079 1080 /* 1081 * Lookup an entry in the cache 1082 * 1083 * Lookup is called with dvp pointing to the directory to search, 1084 * cnp pointing to the name of the entry being sought. If the lookup 1085 * succeeds, the vnode is returned in *vpp, and a status of -1 is 1086 * returned. If the lookup determines that the name does not exist 1087 * (negative caching), a status of ENOENT is returned. If the lookup 1088 * fails, a status of zero is returned. If the directory vnode is 1089 * recycled out from under us due to a forced unmount, a status of 1090 * ENOENT is returned. 1091 * 1092 * vpp is locked and ref'd on return. If we're looking up DOTDOT, dvp is 1093 * unlocked. If we're looking up . an extra ref is taken, but the lock is 1094 * not recursively acquired. 1095 */ 1096 1097 int 1098 cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, 1099 struct timespec *tsp, int *ticksp) 1100 { 1101 struct namecache *ncp; 1102 struct rwlock *blp; 1103 struct mtx *dvlp, *dvlp2; 1104 uint32_t hash; 1105 int error, ltype; 1106 1107 if (__predict_false(!doingcache)) { 1108 cnp->cn_flags &= ~MAKEENTRY; 1109 return (0); 1110 } 1111 retry: 1112 blp = NULL; 1113 dvlp = VP2VNODELOCK(dvp); 1114 error = 0; 1115 counter_u64_add(numcalls, 1); 1116 1117 if (cnp->cn_nameptr[0] == '.') { 1118 if (cnp->cn_namelen == 1) { 1119 *vpp = dvp; 1120 CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .", 1121 dvp, cnp->cn_nameptr); 1122 counter_u64_add(dothits, 1); 1123 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ".", *vpp); 1124 if (tsp != NULL) 1125 timespecclear(tsp); 1126 if (ticksp != NULL) 1127 *ticksp = ticks; 1128 VREF(*vpp); 1129 /* 1130 * When we lookup "." we still can be asked to lock it 1131 * differently... 1132 */ 1133 ltype = cnp->cn_lkflags & LK_TYPE_MASK; 1134 if (ltype != VOP_ISLOCKED(*vpp)) { 1135 if (ltype == LK_EXCLUSIVE) { 1136 vn_lock(*vpp, LK_UPGRADE | LK_RETRY); 1137 if ((*vpp)->v_iflag & VI_DOOMED) { 1138 /* forced unmount */ 1139 vrele(*vpp); 1140 *vpp = NULL; 1141 return (ENOENT); 1142 } 1143 } else 1144 vn_lock(*vpp, LK_DOWNGRADE | LK_RETRY); 1145 } 1146 return (-1); 1147 } 1148 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 1149 counter_u64_add(dotdothits, 1); 1150 dvlp2 = NULL; 1151 mtx_lock(dvlp); 1152 retry_dotdot: 1153 ncp = dvp->v_cache_dd; 1154 if (ncp == NULL) { 1155 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, 1156 "..", NULL); 1157 mtx_unlock(dvlp); 1158 return (0); 1159 } 1160 if ((cnp->cn_flags & MAKEENTRY) == 0) { 1161 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) { 1162 if (ncp->nc_dvp != dvp) 1163 panic("dvp %p v_cache_dd %p\n", dvp, ncp); 1164 if (!cache_zap_locked_vnode_kl2(ncp, 1165 dvp, &dvlp2)) 1166 goto retry_dotdot; 1167 MPASS(dvp->v_cache_dd == NULL); 1168 mtx_unlock(dvlp); 1169 if (dvlp2 != NULL) 1170 mtx_unlock(dvlp2); 1171 cache_free(ncp); 1172 } else { 1173 dvp->v_cache_dd = NULL; 1174 mtx_unlock(dvlp); 1175 if (dvlp2 != NULL) 1176 mtx_unlock(dvlp2); 1177 } 1178 return (0); 1179 } 1180 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) { 1181 if (ncp->nc_flag & NCF_NEGATIVE) 1182 *vpp = NULL; 1183 else 1184 *vpp = ncp->nc_vp; 1185 } else 1186 *vpp = ncp->nc_dvp; 1187 /* Return failure if negative entry was found. */ 1188 if (*vpp == NULL) 1189 goto negative_success; 1190 CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..", 1191 dvp, cnp->cn_nameptr, *vpp); 1192 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, "..", 1193 *vpp); 1194 cache_out_ts(ncp, tsp, ticksp); 1195 if ((ncp->nc_flag & (NCF_ISDOTDOT | NCF_DTS)) == 1196 NCF_DTS && tsp != NULL) 1197 *tsp = ((struct namecache_ts *)ncp)-> 1198 nc_dotdottime; 1199 goto success; 1200 } 1201 } 1202 1203 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp); 1204 blp = HASH2BUCKETLOCK(hash); 1205 rw_rlock(blp); 1206 1207 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 1208 counter_u64_add(numchecks, 1); 1209 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 1210 !bcmp(nc_get_name(ncp), cnp->cn_nameptr, ncp->nc_nlen)) 1211 break; 1212 } 1213 1214 /* We failed to find an entry */ 1215 if (ncp == NULL) { 1216 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr, 1217 NULL); 1218 if ((cnp->cn_flags & MAKEENTRY) == 0) { 1219 counter_u64_add(nummisszap, 1); 1220 } else { 1221 counter_u64_add(nummiss, 1); 1222 } 1223 goto unlock; 1224 } 1225 1226 /* We don't want to have an entry, so dump it */ 1227 if ((cnp->cn_flags & MAKEENTRY) == 0) { 1228 counter_u64_add(numposzaps, 1); 1229 goto zap_and_exit; 1230 } 1231 1232 /* We found a "positive" match, return the vnode */ 1233 if (!(ncp->nc_flag & NCF_NEGATIVE)) { 1234 counter_u64_add(numposhits, 1); 1235 *vpp = ncp->nc_vp; 1236 CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p", 1237 dvp, cnp->cn_nameptr, *vpp, ncp); 1238 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, nc_get_name(ncp), 1239 *vpp); 1240 cache_out_ts(ncp, tsp, ticksp); 1241 goto success; 1242 } 1243 1244 negative_success: 1245 /* We found a negative match, and want to create it, so purge */ 1246 if (cnp->cn_nameiop == CREATE) { 1247 counter_u64_add(numnegzaps, 1); 1248 goto zap_and_exit; 1249 } 1250 1251 counter_u64_add(numneghits, 1); 1252 cache_negative_hit(ncp); 1253 if (ncp->nc_flag & NCF_WHITE) 1254 cnp->cn_flags |= ISWHITEOUT; 1255 SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp, 1256 nc_get_name(ncp)); 1257 cache_out_ts(ncp, tsp, ticksp); 1258 cache_lookup_unlock(blp, dvlp); 1259 return (ENOENT); 1260 1261 success: 1262 /* 1263 * On success we return a locked and ref'd vnode as per the lookup 1264 * protocol. 1265 */ 1266 MPASS(dvp != *vpp); 1267 ltype = 0; /* silence gcc warning */ 1268 if (cnp->cn_flags & ISDOTDOT) { 1269 ltype = VOP_ISLOCKED(dvp); 1270 VOP_UNLOCK(dvp, 0); 1271 } 1272 vhold(*vpp); 1273 cache_lookup_unlock(blp, dvlp); 1274 error = vget(*vpp, cnp->cn_lkflags | LK_VNHELD, cnp->cn_thread); 1275 if (cnp->cn_flags & ISDOTDOT) { 1276 vn_lock(dvp, ltype | LK_RETRY); 1277 if (dvp->v_iflag & VI_DOOMED) { 1278 if (error == 0) 1279 vput(*vpp); 1280 *vpp = NULL; 1281 return (ENOENT); 1282 } 1283 } 1284 if (error) { 1285 *vpp = NULL; 1286 goto retry; 1287 } 1288 if ((cnp->cn_flags & ISLASTCN) && 1289 (cnp->cn_lkflags & LK_TYPE_MASK) == LK_EXCLUSIVE) { 1290 ASSERT_VOP_ELOCKED(*vpp, "cache_lookup"); 1291 } 1292 return (-1); 1293 1294 unlock: 1295 cache_lookup_unlock(blp, dvlp); 1296 return (0); 1297 1298 zap_and_exit: 1299 if (blp != NULL) 1300 error = cache_zap_rlocked_bucket(ncp, blp); 1301 else 1302 error = cache_zap_locked_vnode(ncp, dvp); 1303 if (error != 0) { 1304 zap_and_exit_bucket_fail++; 1305 cache_maybe_yield(); 1306 goto retry; 1307 } 1308 cache_free(ncp); 1309 return (0); 1310 } 1311 1312 struct celockstate { 1313 struct mtx *vlp[3]; 1314 struct rwlock *blp[2]; 1315 }; 1316 CTASSERT((nitems(((struct celockstate *)0)->vlp) == 3)); 1317 CTASSERT((nitems(((struct celockstate *)0)->blp) == 2)); 1318 1319 static inline void 1320 cache_celockstate_init(struct celockstate *cel) 1321 { 1322 1323 bzero(cel, sizeof(*cel)); 1324 } 1325 1326 static void 1327 cache_lock_vnodes_cel(struct celockstate *cel, struct vnode *vp, 1328 struct vnode *dvp) 1329 { 1330 struct mtx *vlp1, *vlp2; 1331 1332 MPASS(cel->vlp[0] == NULL); 1333 MPASS(cel->vlp[1] == NULL); 1334 MPASS(cel->vlp[2] == NULL); 1335 1336 MPASS(vp != NULL || dvp != NULL); 1337 1338 vlp1 = VP2VNODELOCK(vp); 1339 vlp2 = VP2VNODELOCK(dvp); 1340 cache_sort(&vlp1, &vlp2); 1341 1342 if (vlp1 != NULL) { 1343 mtx_lock(vlp1); 1344 cel->vlp[0] = vlp1; 1345 } 1346 mtx_lock(vlp2); 1347 cel->vlp[1] = vlp2; 1348 } 1349 1350 static void 1351 cache_unlock_vnodes_cel(struct celockstate *cel) 1352 { 1353 1354 MPASS(cel->vlp[0] != NULL || cel->vlp[1] != NULL); 1355 1356 if (cel->vlp[0] != NULL) 1357 mtx_unlock(cel->vlp[0]); 1358 if (cel->vlp[1] != NULL) 1359 mtx_unlock(cel->vlp[1]); 1360 if (cel->vlp[2] != NULL) 1361 mtx_unlock(cel->vlp[2]); 1362 } 1363 1364 static bool 1365 cache_lock_vnodes_cel_3(struct celockstate *cel, struct vnode *vp) 1366 { 1367 struct mtx *vlp; 1368 bool ret; 1369 1370 cache_assert_vlp_locked(cel->vlp[0]); 1371 cache_assert_vlp_locked(cel->vlp[1]); 1372 MPASS(cel->vlp[2] == NULL); 1373 1374 MPASS(vp != NULL); 1375 vlp = VP2VNODELOCK(vp); 1376 1377 ret = true; 1378 if (vlp >= cel->vlp[1]) { 1379 mtx_lock(vlp); 1380 } else { 1381 if (mtx_trylock(vlp)) 1382 goto out; 1383 cache_lock_vnodes_cel_3_failures++; 1384 cache_unlock_vnodes_cel(cel); 1385 if (vlp < cel->vlp[0]) { 1386 mtx_lock(vlp); 1387 mtx_lock(cel->vlp[0]); 1388 mtx_lock(cel->vlp[1]); 1389 } else { 1390 if (cel->vlp[0] != NULL) 1391 mtx_lock(cel->vlp[0]); 1392 mtx_lock(vlp); 1393 mtx_lock(cel->vlp[1]); 1394 } 1395 ret = false; 1396 } 1397 out: 1398 cel->vlp[2] = vlp; 1399 return (ret); 1400 } 1401 1402 static void 1403 cache_lock_buckets_cel(struct celockstate *cel, struct rwlock *blp1, 1404 struct rwlock *blp2) 1405 { 1406 1407 MPASS(cel->blp[0] == NULL); 1408 MPASS(cel->blp[1] == NULL); 1409 1410 cache_sort(&blp1, &blp2); 1411 1412 if (blp1 != NULL) { 1413 rw_wlock(blp1); 1414 cel->blp[0] = blp1; 1415 } 1416 rw_wlock(blp2); 1417 cel->blp[1] = blp2; 1418 } 1419 1420 static void 1421 cache_unlock_buckets_cel(struct celockstate *cel) 1422 { 1423 1424 if (cel->blp[0] != NULL) 1425 rw_wunlock(cel->blp[0]); 1426 rw_wunlock(cel->blp[1]); 1427 } 1428 1429 /* 1430 * Lock part of the cache affected by the insertion. 1431 * 1432 * This means vnodelocks for dvp, vp and the relevant bucketlock. 1433 * However, insertion can result in removal of an old entry. In this 1434 * case we have an additional vnode and bucketlock pair to lock. If the 1435 * entry is negative, ncelock is locked instead of the vnode. 1436 * 1437 * That is, in the worst case we have to lock 3 vnodes and 2 bucketlocks, while 1438 * preserving the locking order (smaller address first). 1439 */ 1440 static void 1441 cache_enter_lock(struct celockstate *cel, struct vnode *dvp, struct vnode *vp, 1442 uint32_t hash) 1443 { 1444 struct namecache *ncp; 1445 struct rwlock *blps[2]; 1446 1447 blps[0] = HASH2BUCKETLOCK(hash); 1448 for (;;) { 1449 blps[1] = NULL; 1450 cache_lock_vnodes_cel(cel, dvp, vp); 1451 if (vp == NULL || vp->v_type != VDIR) 1452 break; 1453 ncp = vp->v_cache_dd; 1454 if (ncp == NULL) 1455 break; 1456 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 1457 break; 1458 MPASS(ncp->nc_dvp == vp); 1459 blps[1] = NCP2BUCKETLOCK(ncp); 1460 if (ncp->nc_flag & NCF_NEGATIVE) 1461 break; 1462 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp)) 1463 break; 1464 /* 1465 * All vnodes got re-locked. Re-validate the state and if 1466 * nothing changed we are done. Otherwise restart. 1467 */ 1468 if (ncp == vp->v_cache_dd && 1469 (ncp->nc_flag & NCF_ISDOTDOT) != 0 && 1470 blps[1] == NCP2BUCKETLOCK(ncp) && 1471 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2]) 1472 break; 1473 cache_unlock_vnodes_cel(cel); 1474 cel->vlp[0] = NULL; 1475 cel->vlp[1] = NULL; 1476 cel->vlp[2] = NULL; 1477 } 1478 cache_lock_buckets_cel(cel, blps[0], blps[1]); 1479 } 1480 1481 static void 1482 cache_enter_lock_dd(struct celockstate *cel, struct vnode *dvp, struct vnode *vp, 1483 uint32_t hash) 1484 { 1485 struct namecache *ncp; 1486 struct rwlock *blps[2]; 1487 1488 blps[0] = HASH2BUCKETLOCK(hash); 1489 for (;;) { 1490 blps[1] = NULL; 1491 cache_lock_vnodes_cel(cel, dvp, vp); 1492 ncp = dvp->v_cache_dd; 1493 if (ncp == NULL) 1494 break; 1495 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 1496 break; 1497 MPASS(ncp->nc_dvp == dvp); 1498 blps[1] = NCP2BUCKETLOCK(ncp); 1499 if (ncp->nc_flag & NCF_NEGATIVE) 1500 break; 1501 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp)) 1502 break; 1503 if (ncp == dvp->v_cache_dd && 1504 (ncp->nc_flag & NCF_ISDOTDOT) != 0 && 1505 blps[1] == NCP2BUCKETLOCK(ncp) && 1506 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2]) 1507 break; 1508 cache_unlock_vnodes_cel(cel); 1509 cel->vlp[0] = NULL; 1510 cel->vlp[1] = NULL; 1511 cel->vlp[2] = NULL; 1512 } 1513 cache_lock_buckets_cel(cel, blps[0], blps[1]); 1514 } 1515 1516 static void 1517 cache_enter_unlock(struct celockstate *cel) 1518 { 1519 1520 cache_unlock_buckets_cel(cel); 1521 cache_unlock_vnodes_cel(cel); 1522 } 1523 1524 /* 1525 * Add an entry to the cache. 1526 */ 1527 void 1528 cache_enter_time(struct vnode *dvp, struct vnode *vp, struct componentname *cnp, 1529 struct timespec *tsp, struct timespec *dtsp) 1530 { 1531 struct celockstate cel; 1532 struct namecache *ncp, *n2, *ndd; 1533 struct namecache_ts *n3; 1534 struct nchashhead *ncpp; 1535 struct neglist *neglist; 1536 uint32_t hash; 1537 int flag; 1538 int len; 1539 bool neg_locked; 1540 1541 CTR3(KTR_VFS, "cache_enter(%p, %p, %s)", dvp, vp, cnp->cn_nameptr); 1542 VNASSERT(vp == NULL || (vp->v_iflag & VI_DOOMED) == 0, vp, 1543 ("cache_enter: Adding a doomed vnode")); 1544 VNASSERT(dvp == NULL || (dvp->v_iflag & VI_DOOMED) == 0, dvp, 1545 ("cache_enter: Doomed vnode used as src")); 1546 1547 if (__predict_false(!doingcache)) 1548 return; 1549 1550 /* 1551 * Avoid blowout in namecache entries. 1552 */ 1553 if (__predict_false(numcache >= desiredvnodes * ncsizefactor)) 1554 return; 1555 1556 cache_celockstate_init(&cel); 1557 ndd = NULL; 1558 flag = 0; 1559 if (cnp->cn_nameptr[0] == '.') { 1560 if (cnp->cn_namelen == 1) 1561 return; 1562 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 1563 len = cnp->cn_namelen; 1564 hash = cache_get_hash(cnp->cn_nameptr, len, dvp); 1565 cache_enter_lock_dd(&cel, dvp, vp, hash); 1566 /* 1567 * If dotdot entry already exists, just retarget it 1568 * to new parent vnode, otherwise continue with new 1569 * namecache entry allocation. 1570 */ 1571 if ((ncp = dvp->v_cache_dd) != NULL && 1572 ncp->nc_flag & NCF_ISDOTDOT) { 1573 KASSERT(ncp->nc_dvp == dvp, 1574 ("wrong isdotdot parent")); 1575 neg_locked = false; 1576 if (ncp->nc_flag & NCF_NEGATIVE || vp == NULL) { 1577 neglist = NCP2NEGLIST(ncp); 1578 mtx_lock(&ncneg_hot.nl_lock); 1579 mtx_lock(&neglist->nl_lock); 1580 neg_locked = true; 1581 } 1582 if (!(ncp->nc_flag & NCF_NEGATIVE)) { 1583 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, 1584 ncp, nc_dst); 1585 } else { 1586 cache_negative_remove(ncp, true); 1587 } 1588 if (vp != NULL) { 1589 TAILQ_INSERT_HEAD(&vp->v_cache_dst, 1590 ncp, nc_dst); 1591 ncp->nc_flag &= ~(NCF_NEGATIVE|NCF_HOTNEGATIVE); 1592 } else { 1593 ncp->nc_flag &= ~(NCF_HOTNEGATIVE); 1594 ncp->nc_flag |= NCF_NEGATIVE; 1595 cache_negative_insert(ncp, true); 1596 } 1597 if (neg_locked) { 1598 mtx_unlock(&neglist->nl_lock); 1599 mtx_unlock(&ncneg_hot.nl_lock); 1600 } 1601 ncp->nc_vp = vp; 1602 cache_enter_unlock(&cel); 1603 return; 1604 } 1605 dvp->v_cache_dd = NULL; 1606 cache_enter_unlock(&cel); 1607 cache_celockstate_init(&cel); 1608 SDT_PROBE3(vfs, namecache, enter, done, dvp, "..", vp); 1609 flag = NCF_ISDOTDOT; 1610 } 1611 } 1612 1613 /* 1614 * Calculate the hash key and setup as much of the new 1615 * namecache entry as possible before acquiring the lock. 1616 */ 1617 ncp = cache_alloc(cnp->cn_namelen, tsp != NULL); 1618 ncp->nc_flag = flag; 1619 ncp->nc_vp = vp; 1620 if (vp == NULL) 1621 ncp->nc_flag |= NCF_NEGATIVE; 1622 ncp->nc_dvp = dvp; 1623 if (tsp != NULL) { 1624 n3 = (struct namecache_ts *)ncp; 1625 n3->nc_time = *tsp; 1626 n3->nc_ticks = ticks; 1627 n3->nc_flag |= NCF_TS; 1628 if (dtsp != NULL) { 1629 n3->nc_dotdottime = *dtsp; 1630 n3->nc_flag |= NCF_DTS; 1631 } 1632 } 1633 len = ncp->nc_nlen = cnp->cn_namelen; 1634 hash = cache_get_hash(cnp->cn_nameptr, len, dvp); 1635 strlcpy(nc_get_name(ncp), cnp->cn_nameptr, len + 1); 1636 cache_enter_lock(&cel, dvp, vp, hash); 1637 1638 /* 1639 * See if this vnode or negative entry is already in the cache 1640 * with this name. This can happen with concurrent lookups of 1641 * the same path name. 1642 */ 1643 ncpp = NCHHASH(hash); 1644 LIST_FOREACH(n2, ncpp, nc_hash) { 1645 if (n2->nc_dvp == dvp && 1646 n2->nc_nlen == cnp->cn_namelen && 1647 !bcmp(nc_get_name(n2), cnp->cn_nameptr, n2->nc_nlen)) { 1648 if (tsp != NULL) { 1649 KASSERT((n2->nc_flag & NCF_TS) != 0, 1650 ("no NCF_TS")); 1651 n3 = (struct namecache_ts *)n2; 1652 n3->nc_time = 1653 ((struct namecache_ts *)ncp)->nc_time; 1654 n3->nc_ticks = 1655 ((struct namecache_ts *)ncp)->nc_ticks; 1656 if (dtsp != NULL) { 1657 n3->nc_dotdottime = 1658 ((struct namecache_ts *)ncp)-> 1659 nc_dotdottime; 1660 if (ncp->nc_flag & NCF_NEGATIVE) 1661 mtx_lock(&ncneg_hot.nl_lock); 1662 n3->nc_flag |= NCF_DTS; 1663 if (ncp->nc_flag & NCF_NEGATIVE) 1664 mtx_unlock(&ncneg_hot.nl_lock); 1665 } 1666 } 1667 goto out_unlock_free; 1668 } 1669 } 1670 1671 if (flag == NCF_ISDOTDOT) { 1672 /* 1673 * See if we are trying to add .. entry, but some other lookup 1674 * has populated v_cache_dd pointer already. 1675 */ 1676 if (dvp->v_cache_dd != NULL) 1677 goto out_unlock_free; 1678 KASSERT(vp == NULL || vp->v_type == VDIR, 1679 ("wrong vnode type %p", vp)); 1680 dvp->v_cache_dd = ncp; 1681 } 1682 1683 atomic_add_rel_long(&numcache, 1); 1684 if (vp != NULL) { 1685 if (vp->v_type == VDIR) { 1686 if (flag != NCF_ISDOTDOT) { 1687 /* 1688 * For this case, the cache entry maps both the 1689 * directory name in it and the name ".." for the 1690 * directory's parent. 1691 */ 1692 if ((ndd = vp->v_cache_dd) != NULL) { 1693 if ((ndd->nc_flag & NCF_ISDOTDOT) != 0) 1694 cache_zap_locked(ndd, false); 1695 else 1696 ndd = NULL; 1697 } 1698 vp->v_cache_dd = ncp; 1699 } 1700 } else { 1701 vp->v_cache_dd = NULL; 1702 } 1703 } 1704 1705 if (flag != NCF_ISDOTDOT) { 1706 if (LIST_EMPTY(&dvp->v_cache_src)) { 1707 vhold(dvp); 1708 atomic_add_rel_long(&numcachehv, 1); 1709 } 1710 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); 1711 } 1712 1713 /* 1714 * Insert the new namecache entry into the appropriate chain 1715 * within the cache entries table. 1716 */ 1717 LIST_INSERT_HEAD(ncpp, ncp, nc_hash); 1718 1719 /* 1720 * If the entry is "negative", we place it into the 1721 * "negative" cache queue, otherwise, we place it into the 1722 * destination vnode's cache entries queue. 1723 */ 1724 if (vp != NULL) { 1725 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); 1726 SDT_PROBE3(vfs, namecache, enter, done, dvp, nc_get_name(ncp), 1727 vp); 1728 } else { 1729 if (cnp->cn_flags & ISWHITEOUT) 1730 ncp->nc_flag |= NCF_WHITE; 1731 cache_negative_insert(ncp, false); 1732 SDT_PROBE2(vfs, namecache, enter_negative, done, dvp, 1733 nc_get_name(ncp)); 1734 } 1735 cache_enter_unlock(&cel); 1736 if (numneg * ncnegfactor > numcache) 1737 cache_negative_zap_one(); 1738 cache_free(ndd); 1739 return; 1740 out_unlock_free: 1741 cache_enter_unlock(&cel); 1742 cache_free(ncp); 1743 return; 1744 } 1745 1746 static u_int 1747 cache_roundup_2(u_int val) 1748 { 1749 u_int res; 1750 1751 for (res = 1; res <= val; res <<= 1) 1752 continue; 1753 1754 return (res); 1755 } 1756 1757 /* 1758 * Name cache initialization, from vfs_init() when we are booting 1759 */ 1760 static void 1761 nchinit(void *dummy __unused) 1762 { 1763 u_int i; 1764 1765 cache_zone_small = uma_zcreate("S VFS Cache", 1766 sizeof(struct namecache) + CACHE_PATH_CUTOFF + 1, 1767 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 1768 cache_zone_small_ts = uma_zcreate("STS VFS Cache", 1769 sizeof(struct namecache_ts) + CACHE_PATH_CUTOFF + 1, 1770 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 1771 cache_zone_large = uma_zcreate("L VFS Cache", 1772 sizeof(struct namecache) + NAME_MAX + 1, 1773 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 1774 cache_zone_large_ts = uma_zcreate("LTS VFS Cache", 1775 sizeof(struct namecache_ts) + NAME_MAX + 1, 1776 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 1777 1778 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash); 1779 ncbuckethash = cache_roundup_2(mp_ncpus * 64) - 1; 1780 if (ncbuckethash > nchash) 1781 ncbuckethash = nchash; 1782 bucketlocks = malloc(sizeof(*bucketlocks) * numbucketlocks, M_VFSCACHE, 1783 M_WAITOK | M_ZERO); 1784 for (i = 0; i < numbucketlocks; i++) 1785 rw_init_flags(&bucketlocks[i], "ncbuc", RW_DUPOK | RW_RECURSE); 1786 ncvnodehash = cache_roundup_2(mp_ncpus * 64) - 1; 1787 vnodelocks = malloc(sizeof(*vnodelocks) * numvnodelocks, M_VFSCACHE, 1788 M_WAITOK | M_ZERO); 1789 for (i = 0; i < numvnodelocks; i++) 1790 mtx_init(&vnodelocks[i], "ncvn", NULL, MTX_DUPOK | MTX_RECURSE); 1791 ncpurgeminvnodes = numbucketlocks; 1792 1793 ncneghash = 3; 1794 neglists = malloc(sizeof(*neglists) * numneglists, M_VFSCACHE, 1795 M_WAITOK | M_ZERO); 1796 for (i = 0; i < numneglists; i++) { 1797 mtx_init(&neglists[i].nl_lock, "ncnegl", NULL, MTX_DEF); 1798 TAILQ_INIT(&neglists[i].nl_list); 1799 } 1800 mtx_init(&ncneg_hot.nl_lock, "ncneglh", NULL, MTX_DEF); 1801 TAILQ_INIT(&ncneg_hot.nl_list); 1802 1803 mtx_init(&ncneg_shrink_lock, "ncnegs", NULL, MTX_DEF); 1804 1805 numcalls = counter_u64_alloc(M_WAITOK); 1806 dothits = counter_u64_alloc(M_WAITOK); 1807 dotdothits = counter_u64_alloc(M_WAITOK); 1808 numchecks = counter_u64_alloc(M_WAITOK); 1809 nummiss = counter_u64_alloc(M_WAITOK); 1810 nummisszap = counter_u64_alloc(M_WAITOK); 1811 numposzaps = counter_u64_alloc(M_WAITOK); 1812 numposhits = counter_u64_alloc(M_WAITOK); 1813 numnegzaps = counter_u64_alloc(M_WAITOK); 1814 numneghits = counter_u64_alloc(M_WAITOK); 1815 numfullpathcalls = counter_u64_alloc(M_WAITOK); 1816 numfullpathfail1 = counter_u64_alloc(M_WAITOK); 1817 numfullpathfail2 = counter_u64_alloc(M_WAITOK); 1818 numfullpathfail4 = counter_u64_alloc(M_WAITOK); 1819 numfullpathfound = counter_u64_alloc(M_WAITOK); 1820 } 1821 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL); 1822 1823 void 1824 cache_changesize(int newmaxvnodes) 1825 { 1826 struct nchashhead *new_nchashtbl, *old_nchashtbl; 1827 u_long new_nchash, old_nchash; 1828 struct namecache *ncp; 1829 uint32_t hash; 1830 int i; 1831 1832 newmaxvnodes = cache_roundup_2(newmaxvnodes * 2); 1833 if (newmaxvnodes < numbucketlocks) 1834 newmaxvnodes = numbucketlocks; 1835 1836 new_nchashtbl = hashinit(newmaxvnodes, M_VFSCACHE, &new_nchash); 1837 /* If same hash table size, nothing to do */ 1838 if (nchash == new_nchash) { 1839 free(new_nchashtbl, M_VFSCACHE); 1840 return; 1841 } 1842 /* 1843 * Move everything from the old hash table to the new table. 1844 * None of the namecache entries in the table can be removed 1845 * because to do so, they have to be removed from the hash table. 1846 */ 1847 cache_lock_all_vnodes(); 1848 cache_lock_all_buckets(); 1849 old_nchashtbl = nchashtbl; 1850 old_nchash = nchash; 1851 nchashtbl = new_nchashtbl; 1852 nchash = new_nchash; 1853 for (i = 0; i <= old_nchash; i++) { 1854 while ((ncp = LIST_FIRST(&old_nchashtbl[i])) != NULL) { 1855 hash = cache_get_hash(nc_get_name(ncp), ncp->nc_nlen, 1856 ncp->nc_dvp); 1857 LIST_REMOVE(ncp, nc_hash); 1858 LIST_INSERT_HEAD(NCHHASH(hash), ncp, nc_hash); 1859 } 1860 } 1861 cache_unlock_all_buckets(); 1862 cache_unlock_all_vnodes(); 1863 free(old_nchashtbl, M_VFSCACHE); 1864 } 1865 1866 /* 1867 * Invalidate all entries to a particular vnode. 1868 */ 1869 void 1870 cache_purge(struct vnode *vp) 1871 { 1872 TAILQ_HEAD(, namecache) ncps; 1873 struct namecache *ncp, *nnp; 1874 struct mtx *vlp, *vlp2; 1875 1876 CTR1(KTR_VFS, "cache_purge(%p)", vp); 1877 SDT_PROBE1(vfs, namecache, purge, done, vp); 1878 if (LIST_EMPTY(&vp->v_cache_src) && TAILQ_EMPTY(&vp->v_cache_dst) && 1879 vp->v_cache_dd == NULL) 1880 return; 1881 TAILQ_INIT(&ncps); 1882 vlp = VP2VNODELOCK(vp); 1883 vlp2 = NULL; 1884 mtx_lock(vlp); 1885 retry: 1886 while (!LIST_EMPTY(&vp->v_cache_src)) { 1887 ncp = LIST_FIRST(&vp->v_cache_src); 1888 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 1889 goto retry; 1890 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 1891 } 1892 while (!TAILQ_EMPTY(&vp->v_cache_dst)) { 1893 ncp = TAILQ_FIRST(&vp->v_cache_dst); 1894 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 1895 goto retry; 1896 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 1897 } 1898 ncp = vp->v_cache_dd; 1899 if (ncp != NULL) { 1900 KASSERT(ncp->nc_flag & NCF_ISDOTDOT, 1901 ("lost dotdot link")); 1902 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 1903 goto retry; 1904 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 1905 } 1906 KASSERT(vp->v_cache_dd == NULL, ("incomplete purge")); 1907 mtx_unlock(vlp); 1908 if (vlp2 != NULL) 1909 mtx_unlock(vlp2); 1910 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { 1911 cache_free(ncp); 1912 } 1913 } 1914 1915 /* 1916 * Invalidate all negative entries for a particular directory vnode. 1917 */ 1918 void 1919 cache_purge_negative(struct vnode *vp) 1920 { 1921 TAILQ_HEAD(, namecache) ncps; 1922 struct namecache *ncp, *nnp; 1923 struct mtx *vlp; 1924 1925 CTR1(KTR_VFS, "cache_purge_negative(%p)", vp); 1926 SDT_PROBE1(vfs, namecache, purge_negative, done, vp); 1927 TAILQ_INIT(&ncps); 1928 vlp = VP2VNODELOCK(vp); 1929 mtx_lock(vlp); 1930 LIST_FOREACH_SAFE(ncp, &vp->v_cache_src, nc_src, nnp) { 1931 if (!(ncp->nc_flag & NCF_NEGATIVE)) 1932 continue; 1933 cache_zap_negative_locked_vnode_kl(ncp, vp); 1934 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 1935 } 1936 mtx_unlock(vlp); 1937 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { 1938 cache_free(ncp); 1939 } 1940 } 1941 1942 /* 1943 * Flush all entries referencing a particular filesystem. 1944 */ 1945 void 1946 cache_purgevfs(struct mount *mp, bool force) 1947 { 1948 TAILQ_HEAD(, namecache) ncps; 1949 struct mtx *vlp1, *vlp2; 1950 struct rwlock *blp; 1951 struct nchashhead *bucket; 1952 struct namecache *ncp, *nnp; 1953 u_long i, j, n_nchash; 1954 int error; 1955 1956 /* Scan hash tables for applicable entries */ 1957 SDT_PROBE1(vfs, namecache, purgevfs, done, mp); 1958 if (!force && mp->mnt_nvnodelistsize <= ncpurgeminvnodes) 1959 return; 1960 TAILQ_INIT(&ncps); 1961 n_nchash = nchash + 1; 1962 vlp1 = vlp2 = NULL; 1963 for (i = 0; i < numbucketlocks; i++) { 1964 blp = (struct rwlock *)&bucketlocks[i]; 1965 rw_wlock(blp); 1966 for (j = i; j < n_nchash; j += numbucketlocks) { 1967 retry: 1968 bucket = &nchashtbl[j]; 1969 LIST_FOREACH_SAFE(ncp, bucket, nc_hash, nnp) { 1970 cache_assert_bucket_locked(ncp, RA_WLOCKED); 1971 if (ncp->nc_dvp->v_mount != mp) 1972 continue; 1973 error = cache_zap_wlocked_bucket_kl(ncp, blp, 1974 &vlp1, &vlp2); 1975 if (error != 0) 1976 goto retry; 1977 TAILQ_INSERT_HEAD(&ncps, ncp, nc_dst); 1978 } 1979 } 1980 rw_wunlock(blp); 1981 if (vlp1 == NULL && vlp2 == NULL) 1982 cache_maybe_yield(); 1983 } 1984 if (vlp1 != NULL) 1985 mtx_unlock(vlp1); 1986 if (vlp2 != NULL) 1987 mtx_unlock(vlp2); 1988 1989 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { 1990 cache_free(ncp); 1991 } 1992 } 1993 1994 /* 1995 * Perform canonical checks and cache lookup and pass on to filesystem 1996 * through the vop_cachedlookup only if needed. 1997 */ 1998 1999 int 2000 vfs_cache_lookup(struct vop_lookup_args *ap) 2001 { 2002 struct vnode *dvp; 2003 int error; 2004 struct vnode **vpp = ap->a_vpp; 2005 struct componentname *cnp = ap->a_cnp; 2006 struct ucred *cred = cnp->cn_cred; 2007 int flags = cnp->cn_flags; 2008 struct thread *td = cnp->cn_thread; 2009 2010 *vpp = NULL; 2011 dvp = ap->a_dvp; 2012 2013 if (dvp->v_type != VDIR) 2014 return (ENOTDIR); 2015 2016 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && 2017 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 2018 return (EROFS); 2019 2020 error = VOP_ACCESS(dvp, VEXEC, cred, td); 2021 if (error) 2022 return (error); 2023 2024 error = cache_lookup(dvp, vpp, cnp, NULL, NULL); 2025 if (error == 0) 2026 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); 2027 if (error == -1) 2028 return (0); 2029 return (error); 2030 } 2031 2032 /* 2033 * XXX All of these sysctls would probably be more productive dead. 2034 */ 2035 static int disablecwd; 2036 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, 2037 "Disable the getcwd syscall"); 2038 2039 /* Implementation of the getcwd syscall. */ 2040 int 2041 sys___getcwd(struct thread *td, struct __getcwd_args *uap) 2042 { 2043 2044 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen, 2045 MAXPATHLEN)); 2046 } 2047 2048 int 2049 kern___getcwd(struct thread *td, char *buf, enum uio_seg bufseg, u_int buflen, 2050 u_int path_max) 2051 { 2052 char *bp, *tmpbuf; 2053 struct filedesc *fdp; 2054 struct vnode *cdir, *rdir; 2055 int error; 2056 2057 if (__predict_false(disablecwd)) 2058 return (ENODEV); 2059 if (__predict_false(buflen < 2)) 2060 return (EINVAL); 2061 if (buflen > path_max) 2062 buflen = path_max; 2063 2064 tmpbuf = malloc(buflen, M_TEMP, M_WAITOK); 2065 fdp = td->td_proc->p_fd; 2066 FILEDESC_SLOCK(fdp); 2067 cdir = fdp->fd_cdir; 2068 vrefact(cdir); 2069 rdir = fdp->fd_rdir; 2070 vrefact(rdir); 2071 FILEDESC_SUNLOCK(fdp); 2072 error = vn_fullpath1(td, cdir, rdir, tmpbuf, &bp, buflen); 2073 vrele(rdir); 2074 vrele(cdir); 2075 2076 if (!error) { 2077 if (bufseg == UIO_SYSSPACE) 2078 bcopy(bp, buf, strlen(bp) + 1); 2079 else 2080 error = copyout(bp, buf, strlen(bp) + 1); 2081 #ifdef KTRACE 2082 if (KTRPOINT(curthread, KTR_NAMEI)) 2083 ktrnamei(bp); 2084 #endif 2085 } 2086 free(tmpbuf, M_TEMP); 2087 return (error); 2088 } 2089 2090 /* 2091 * Thus begins the fullpath magic. 2092 */ 2093 2094 static int disablefullpath; 2095 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0, 2096 "Disable the vn_fullpath function"); 2097 2098 /* 2099 * Retrieve the full filesystem path that correspond to a vnode from the name 2100 * cache (if available) 2101 */ 2102 int 2103 vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf) 2104 { 2105 char *buf; 2106 struct filedesc *fdp; 2107 struct vnode *rdir; 2108 int error; 2109 2110 if (__predict_false(disablefullpath)) 2111 return (ENODEV); 2112 if (__predict_false(vn == NULL)) 2113 return (EINVAL); 2114 2115 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 2116 fdp = td->td_proc->p_fd; 2117 FILEDESC_SLOCK(fdp); 2118 rdir = fdp->fd_rdir; 2119 VREF(rdir); 2120 FILEDESC_SUNLOCK(fdp); 2121 error = vn_fullpath1(td, vn, rdir, buf, retbuf, MAXPATHLEN); 2122 vrele(rdir); 2123 2124 if (!error) 2125 *freebuf = buf; 2126 else 2127 free(buf, M_TEMP); 2128 return (error); 2129 } 2130 2131 /* 2132 * This function is similar to vn_fullpath, but it attempts to lookup the 2133 * pathname relative to the global root mount point. This is required for the 2134 * auditing sub-system, as audited pathnames must be absolute, relative to the 2135 * global root mount point. 2136 */ 2137 int 2138 vn_fullpath_global(struct thread *td, struct vnode *vn, 2139 char **retbuf, char **freebuf) 2140 { 2141 char *buf; 2142 int error; 2143 2144 if (__predict_false(disablefullpath)) 2145 return (ENODEV); 2146 if (__predict_false(vn == NULL)) 2147 return (EINVAL); 2148 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 2149 error = vn_fullpath1(td, vn, rootvnode, buf, retbuf, MAXPATHLEN); 2150 if (!error) 2151 *freebuf = buf; 2152 else 2153 free(buf, M_TEMP); 2154 return (error); 2155 } 2156 2157 int 2158 vn_vptocnp(struct vnode **vp, struct ucred *cred, char *buf, u_int *buflen) 2159 { 2160 struct vnode *dvp; 2161 struct namecache *ncp; 2162 struct mtx *vlp; 2163 int error; 2164 2165 vlp = VP2VNODELOCK(*vp); 2166 mtx_lock(vlp); 2167 TAILQ_FOREACH(ncp, &((*vp)->v_cache_dst), nc_dst) { 2168 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 2169 break; 2170 } 2171 if (ncp != NULL) { 2172 if (*buflen < ncp->nc_nlen) { 2173 mtx_unlock(vlp); 2174 vrele(*vp); 2175 counter_u64_add(numfullpathfail4, 1); 2176 error = ENOMEM; 2177 SDT_PROBE3(vfs, namecache, fullpath, return, error, 2178 vp, NULL); 2179 return (error); 2180 } 2181 *buflen -= ncp->nc_nlen; 2182 memcpy(buf + *buflen, nc_get_name(ncp), ncp->nc_nlen); 2183 SDT_PROBE3(vfs, namecache, fullpath, hit, ncp->nc_dvp, 2184 nc_get_name(ncp), vp); 2185 dvp = *vp; 2186 *vp = ncp->nc_dvp; 2187 vref(*vp); 2188 mtx_unlock(vlp); 2189 vrele(dvp); 2190 return (0); 2191 } 2192 SDT_PROBE1(vfs, namecache, fullpath, miss, vp); 2193 2194 mtx_unlock(vlp); 2195 vn_lock(*vp, LK_SHARED | LK_RETRY); 2196 error = VOP_VPTOCNP(*vp, &dvp, cred, buf, buflen); 2197 vput(*vp); 2198 if (error) { 2199 counter_u64_add(numfullpathfail2, 1); 2200 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); 2201 return (error); 2202 } 2203 2204 *vp = dvp; 2205 if (dvp->v_iflag & VI_DOOMED) { 2206 /* forced unmount */ 2207 vrele(dvp); 2208 error = ENOENT; 2209 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); 2210 return (error); 2211 } 2212 /* 2213 * *vp has its use count incremented still. 2214 */ 2215 2216 return (0); 2217 } 2218 2219 /* 2220 * The magic behind kern___getcwd() and vn_fullpath(). 2221 */ 2222 static int 2223 vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 2224 char *buf, char **retbuf, u_int buflen) 2225 { 2226 int error, slash_prefixed; 2227 #ifdef KDTRACE_HOOKS 2228 struct vnode *startvp = vp; 2229 #endif 2230 struct vnode *vp1; 2231 2232 buflen--; 2233 buf[buflen] = '\0'; 2234 error = 0; 2235 slash_prefixed = 0; 2236 2237 SDT_PROBE1(vfs, namecache, fullpath, entry, vp); 2238 counter_u64_add(numfullpathcalls, 1); 2239 vref(vp); 2240 if (vp->v_type != VDIR) { 2241 error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen); 2242 if (error) 2243 return (error); 2244 if (buflen == 0) { 2245 vrele(vp); 2246 return (ENOMEM); 2247 } 2248 buf[--buflen] = '/'; 2249 slash_prefixed = 1; 2250 } 2251 while (vp != rdir && vp != rootvnode) { 2252 /* 2253 * The vp vnode must be already fully constructed, 2254 * since it is either found in namecache or obtained 2255 * from VOP_VPTOCNP(). We may test for VV_ROOT safely 2256 * without obtaining the vnode lock. 2257 */ 2258 if ((vp->v_vflag & VV_ROOT) != 0) { 2259 vn_lock(vp, LK_RETRY | LK_SHARED); 2260 2261 /* 2262 * With the vnode locked, check for races with 2263 * unmount, forced or not. Note that we 2264 * already verified that vp is not equal to 2265 * the root vnode, which means that 2266 * mnt_vnodecovered can be NULL only for the 2267 * case of unmount. 2268 */ 2269 if ((vp->v_iflag & VI_DOOMED) != 0 || 2270 (vp1 = vp->v_mount->mnt_vnodecovered) == NULL || 2271 vp1->v_mountedhere != vp->v_mount) { 2272 vput(vp); 2273 error = ENOENT; 2274 SDT_PROBE3(vfs, namecache, fullpath, return, 2275 error, vp, NULL); 2276 break; 2277 } 2278 2279 vref(vp1); 2280 vput(vp); 2281 vp = vp1; 2282 continue; 2283 } 2284 if (vp->v_type != VDIR) { 2285 vrele(vp); 2286 counter_u64_add(numfullpathfail1, 1); 2287 error = ENOTDIR; 2288 SDT_PROBE3(vfs, namecache, fullpath, return, 2289 error, vp, NULL); 2290 break; 2291 } 2292 error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen); 2293 if (error) 2294 break; 2295 if (buflen == 0) { 2296 vrele(vp); 2297 error = ENOMEM; 2298 SDT_PROBE3(vfs, namecache, fullpath, return, error, 2299 startvp, NULL); 2300 break; 2301 } 2302 buf[--buflen] = '/'; 2303 slash_prefixed = 1; 2304 } 2305 if (error) 2306 return (error); 2307 if (!slash_prefixed) { 2308 if (buflen == 0) { 2309 vrele(vp); 2310 counter_u64_add(numfullpathfail4, 1); 2311 SDT_PROBE3(vfs, namecache, fullpath, return, ENOMEM, 2312 startvp, NULL); 2313 return (ENOMEM); 2314 } 2315 buf[--buflen] = '/'; 2316 } 2317 counter_u64_add(numfullpathfound, 1); 2318 vrele(vp); 2319 2320 SDT_PROBE3(vfs, namecache, fullpath, return, 0, startvp, buf + buflen); 2321 *retbuf = buf + buflen; 2322 return (0); 2323 } 2324 2325 struct vnode * 2326 vn_dir_dd_ino(struct vnode *vp) 2327 { 2328 struct namecache *ncp; 2329 struct vnode *ddvp; 2330 struct mtx *vlp; 2331 2332 ASSERT_VOP_LOCKED(vp, "vn_dir_dd_ino"); 2333 vlp = VP2VNODELOCK(vp); 2334 mtx_lock(vlp); 2335 TAILQ_FOREACH(ncp, &(vp->v_cache_dst), nc_dst) { 2336 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) 2337 continue; 2338 ddvp = ncp->nc_dvp; 2339 vhold(ddvp); 2340 mtx_unlock(vlp); 2341 if (vget(ddvp, LK_SHARED | LK_NOWAIT | LK_VNHELD, curthread)) 2342 return (NULL); 2343 return (ddvp); 2344 } 2345 mtx_unlock(vlp); 2346 return (NULL); 2347 } 2348 2349 int 2350 vn_commname(struct vnode *vp, char *buf, u_int buflen) 2351 { 2352 struct namecache *ncp; 2353 struct mtx *vlp; 2354 int l; 2355 2356 vlp = VP2VNODELOCK(vp); 2357 mtx_lock(vlp); 2358 TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst) 2359 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 2360 break; 2361 if (ncp == NULL) { 2362 mtx_unlock(vlp); 2363 return (ENOENT); 2364 } 2365 l = min(ncp->nc_nlen, buflen - 1); 2366 memcpy(buf, nc_get_name(ncp), l); 2367 mtx_unlock(vlp); 2368 buf[l] = '\0'; 2369 return (0); 2370 } 2371 2372 /* ABI compat shims for old kernel modules. */ 2373 #undef cache_enter 2374 2375 void cache_enter(struct vnode *dvp, struct vnode *vp, 2376 struct componentname *cnp); 2377 2378 void 2379 cache_enter(struct vnode *dvp, struct vnode *vp, struct componentname *cnp) 2380 { 2381 2382 cache_enter_time(dvp, vp, cnp, NULL, NULL); 2383 } 2384 2385 /* 2386 * This function updates path string to vnode's full global path 2387 * and checks the size of the new path string against the pathlen argument. 2388 * 2389 * Requires a locked, referenced vnode. 2390 * Vnode is re-locked on success or ENODEV, otherwise unlocked. 2391 * 2392 * If sysctl debug.disablefullpath is set, ENODEV is returned, 2393 * vnode is left locked and path remain untouched. 2394 * 2395 * If vp is a directory, the call to vn_fullpath_global() always succeeds 2396 * because it falls back to the ".." lookup if the namecache lookup fails. 2397 */ 2398 int 2399 vn_path_to_global_path(struct thread *td, struct vnode *vp, char *path, 2400 u_int pathlen) 2401 { 2402 struct nameidata nd; 2403 struct vnode *vp1; 2404 char *rpath, *fbuf; 2405 int error; 2406 2407 ASSERT_VOP_ELOCKED(vp, __func__); 2408 2409 /* Return ENODEV if sysctl debug.disablefullpath==1 */ 2410 if (__predict_false(disablefullpath)) 2411 return (ENODEV); 2412 2413 /* Construct global filesystem path from vp. */ 2414 VOP_UNLOCK(vp, 0); 2415 error = vn_fullpath_global(td, vp, &rpath, &fbuf); 2416 2417 if (error != 0) { 2418 vrele(vp); 2419 return (error); 2420 } 2421 2422 if (strlen(rpath) >= pathlen) { 2423 vrele(vp); 2424 error = ENAMETOOLONG; 2425 goto out; 2426 } 2427 2428 /* 2429 * Re-lookup the vnode by path to detect a possible rename. 2430 * As a side effect, the vnode is relocked. 2431 * If vnode was renamed, return ENOENT. 2432 */ 2433 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1, 2434 UIO_SYSSPACE, path, td); 2435 error = namei(&nd); 2436 if (error != 0) { 2437 vrele(vp); 2438 goto out; 2439 } 2440 NDFREE(&nd, NDF_ONLY_PNBUF); 2441 vp1 = nd.ni_vp; 2442 vrele(vp); 2443 if (vp1 == vp) 2444 strcpy(path, rpath); 2445 else { 2446 vput(vp1); 2447 error = ENOENT; 2448 } 2449 2450 out: 2451 free(fbuf, M_TEMP); 2452 return (error); 2453 } 2454