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