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 } else { 739 mtx_assert(&neglist->nl_lock, MA_OWNED); 740 mtx_assert(&ncneg_hot.nl_lock, MA_OWNED); 741 } 742 if (ncp->nc_flag & NCF_HOTNEGATIVE) { 743 TAILQ_REMOVE(&ncneg_hot.nl_list, ncp, nc_dst); 744 } else { 745 TAILQ_REMOVE(&neglist->nl_list, ncp, nc_dst); 746 } 747 if (list_locked) 748 mtx_unlock(&neglist->nl_lock); 749 if (hot_locked) 750 mtx_unlock(&ncneg_hot.nl_lock); 751 atomic_subtract_rel_long(&numneg, 1); 752 } 753 754 static void 755 cache_negative_shrink_select(int start, struct namecache **ncpp, 756 struct neglist **neglistpp) 757 { 758 struct neglist *neglist; 759 struct namecache *ncp; 760 int i; 761 762 *ncpp = ncp = NULL; 763 764 for (i = start; i < numneglists; i++) { 765 neglist = &neglists[i]; 766 if (TAILQ_FIRST(&neglist->nl_list) == NULL) 767 continue; 768 mtx_lock(&neglist->nl_lock); 769 ncp = TAILQ_FIRST(&neglist->nl_list); 770 if (ncp != NULL) 771 break; 772 mtx_unlock(&neglist->nl_lock); 773 } 774 775 *neglistpp = neglist; 776 *ncpp = ncp; 777 } 778 779 static void 780 cache_negative_zap_one(void) 781 { 782 struct namecache *ncp, *ncp2; 783 struct neglist *neglist; 784 struct mtx *dvlp; 785 struct rwlock *blp; 786 787 if (!mtx_trylock(&ncneg_shrink_lock)) 788 return; 789 790 mtx_lock(&ncneg_hot.nl_lock); 791 ncp = TAILQ_FIRST(&ncneg_hot.nl_list); 792 if (ncp != NULL) { 793 neglist = NCP2NEGLIST(ncp); 794 mtx_lock(&neglist->nl_lock); 795 TAILQ_REMOVE(&ncneg_hot.nl_list, ncp, nc_dst); 796 TAILQ_INSERT_TAIL(&neglist->nl_list, ncp, nc_dst); 797 ncp->nc_flag &= ~NCF_HOTNEGATIVE; 798 mtx_unlock(&neglist->nl_lock); 799 } 800 801 cache_negative_shrink_select(shrink_list_turn, &ncp, &neglist); 802 shrink_list_turn++; 803 if (shrink_list_turn == numneglists) 804 shrink_list_turn = 0; 805 if (ncp == NULL && shrink_list_turn == 0) 806 cache_negative_shrink_select(shrink_list_turn, &ncp, &neglist); 807 if (ncp == NULL) { 808 mtx_unlock(&ncneg_hot.nl_lock); 809 goto out; 810 } 811 812 MPASS(ncp->nc_flag & NCF_NEGATIVE); 813 dvlp = VP2VNODELOCK(ncp->nc_dvp); 814 blp = NCP2BUCKETLOCK(ncp); 815 mtx_unlock(&neglist->nl_lock); 816 mtx_unlock(&ncneg_hot.nl_lock); 817 mtx_lock(dvlp); 818 rw_wlock(blp); 819 mtx_lock(&ncneg_hot.nl_lock); 820 mtx_lock(&neglist->nl_lock); 821 ncp2 = TAILQ_FIRST(&neglist->nl_list); 822 if (ncp != ncp2 || dvlp != VP2VNODELOCK(ncp2->nc_dvp) || 823 blp != NCP2BUCKETLOCK(ncp2) || !(ncp2->nc_flag & NCF_NEGATIVE)) { 824 ncp = NULL; 825 goto out_unlock_all; 826 } 827 SDT_PROBE3(vfs, namecache, shrink_negative, done, ncp->nc_dvp, 828 nc_get_name(ncp), ncp->nc_neghits); 829 830 cache_zap_locked(ncp, true); 831 out_unlock_all: 832 mtx_unlock(&neglist->nl_lock); 833 mtx_unlock(&ncneg_hot.nl_lock); 834 rw_wunlock(blp); 835 mtx_unlock(dvlp); 836 out: 837 mtx_unlock(&ncneg_shrink_lock); 838 cache_free(ncp); 839 } 840 841 /* 842 * cache_zap_locked(): 843 * 844 * Removes a namecache entry from cache, whether it contains an actual 845 * pointer to a vnode or if it is just a negative cache entry. 846 */ 847 static void 848 cache_zap_locked(struct namecache *ncp, bool neg_locked) 849 { 850 851 if (!(ncp->nc_flag & NCF_NEGATIVE)) 852 cache_assert_vnode_locked(ncp->nc_vp); 853 cache_assert_vnode_locked(ncp->nc_dvp); 854 cache_assert_bucket_locked(ncp, RA_WLOCKED); 855 856 CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp, 857 (ncp->nc_flag & NCF_NEGATIVE) ? NULL : ncp->nc_vp); 858 if (!(ncp->nc_flag & NCF_NEGATIVE)) { 859 SDT_PROBE3(vfs, namecache, zap, done, ncp->nc_dvp, 860 nc_get_name(ncp), ncp->nc_vp); 861 } else { 862 SDT_PROBE3(vfs, namecache, zap_negative, done, ncp->nc_dvp, 863 nc_get_name(ncp), ncp->nc_neghits); 864 } 865 LIST_REMOVE(ncp, nc_hash); 866 if (!(ncp->nc_flag & NCF_NEGATIVE)) { 867 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst); 868 if (ncp == ncp->nc_vp->v_cache_dd) 869 ncp->nc_vp->v_cache_dd = NULL; 870 } else { 871 cache_negative_remove(ncp, neg_locked); 872 } 873 if (ncp->nc_flag & NCF_ISDOTDOT) { 874 if (ncp == ncp->nc_dvp->v_cache_dd) 875 ncp->nc_dvp->v_cache_dd = NULL; 876 } else { 877 LIST_REMOVE(ncp, nc_src); 878 if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) { 879 ncp->nc_flag |= NCF_DVDROP; 880 atomic_subtract_rel_long(&numcachehv, 1); 881 } 882 } 883 atomic_subtract_rel_long(&numcache, 1); 884 } 885 886 static void 887 cache_zap_negative_locked_vnode_kl(struct namecache *ncp, struct vnode *vp) 888 { 889 struct rwlock *blp; 890 891 MPASS(ncp->nc_dvp == vp); 892 MPASS(ncp->nc_flag & NCF_NEGATIVE); 893 cache_assert_vnode_locked(vp); 894 895 blp = NCP2BUCKETLOCK(ncp); 896 rw_wlock(blp); 897 cache_zap_locked(ncp, false); 898 rw_wunlock(blp); 899 } 900 901 static bool 902 cache_zap_locked_vnode_kl2(struct namecache *ncp, struct vnode *vp, 903 struct mtx **vlpp) 904 { 905 struct mtx *pvlp, *vlp1, *vlp2, *to_unlock; 906 struct rwlock *blp; 907 908 MPASS(vp == ncp->nc_dvp || vp == ncp->nc_vp); 909 cache_assert_vnode_locked(vp); 910 911 if (ncp->nc_flag & NCF_NEGATIVE) { 912 if (*vlpp != NULL) { 913 mtx_unlock(*vlpp); 914 *vlpp = NULL; 915 } 916 cache_zap_negative_locked_vnode_kl(ncp, vp); 917 return (true); 918 } 919 920 pvlp = VP2VNODELOCK(vp); 921 blp = NCP2BUCKETLOCK(ncp); 922 vlp1 = VP2VNODELOCK(ncp->nc_dvp); 923 vlp2 = VP2VNODELOCK(ncp->nc_vp); 924 925 if (*vlpp == vlp1 || *vlpp == vlp2) { 926 to_unlock = *vlpp; 927 *vlpp = NULL; 928 } else { 929 if (*vlpp != NULL) { 930 mtx_unlock(*vlpp); 931 *vlpp = NULL; 932 } 933 cache_sort(&vlp1, &vlp2); 934 if (vlp1 == pvlp) { 935 mtx_lock(vlp2); 936 to_unlock = vlp2; 937 } else { 938 if (!mtx_trylock(vlp1)) 939 goto out_relock; 940 to_unlock = vlp1; 941 } 942 } 943 rw_wlock(blp); 944 cache_zap_locked(ncp, false); 945 rw_wunlock(blp); 946 if (to_unlock != NULL) 947 mtx_unlock(to_unlock); 948 return (true); 949 950 out_relock: 951 mtx_unlock(vlp2); 952 mtx_lock(vlp1); 953 mtx_lock(vlp2); 954 MPASS(*vlpp == NULL); 955 *vlpp = vlp1; 956 return (false); 957 } 958 959 static int 960 cache_zap_locked_vnode(struct namecache *ncp, struct vnode *vp) 961 { 962 struct mtx *pvlp, *vlp1, *vlp2, *to_unlock; 963 struct rwlock *blp; 964 int error = 0; 965 966 MPASS(vp == ncp->nc_dvp || vp == ncp->nc_vp); 967 cache_assert_vnode_locked(vp); 968 969 pvlp = VP2VNODELOCK(vp); 970 if (ncp->nc_flag & NCF_NEGATIVE) { 971 cache_zap_negative_locked_vnode_kl(ncp, vp); 972 goto out; 973 } 974 975 blp = NCP2BUCKETLOCK(ncp); 976 vlp1 = VP2VNODELOCK(ncp->nc_dvp); 977 vlp2 = VP2VNODELOCK(ncp->nc_vp); 978 cache_sort(&vlp1, &vlp2); 979 if (vlp1 == pvlp) { 980 mtx_lock(vlp2); 981 to_unlock = vlp2; 982 } else { 983 if (!mtx_trylock(vlp1)) { 984 error = EAGAIN; 985 goto out; 986 } 987 to_unlock = vlp1; 988 } 989 rw_wlock(blp); 990 cache_zap_locked(ncp, false); 991 rw_wunlock(blp); 992 mtx_unlock(to_unlock); 993 out: 994 mtx_unlock(pvlp); 995 return (error); 996 } 997 998 static int 999 cache_zap_rlocked_bucket(struct namecache *ncp, struct rwlock *blp) 1000 { 1001 struct mtx *dvlp, *vlp; 1002 1003 cache_assert_bucket_locked(ncp, RA_RLOCKED); 1004 1005 dvlp = VP2VNODELOCK(ncp->nc_dvp); 1006 vlp = NULL; 1007 if (!(ncp->nc_flag & NCF_NEGATIVE)) 1008 vlp = VP2VNODELOCK(ncp->nc_vp); 1009 if (cache_trylock_vnodes(dvlp, vlp) == 0) { 1010 rw_runlock(blp); 1011 rw_wlock(blp); 1012 cache_zap_locked(ncp, false); 1013 rw_wunlock(blp); 1014 cache_unlock_vnodes(dvlp, vlp); 1015 return (0); 1016 } 1017 1018 rw_runlock(blp); 1019 return (EAGAIN); 1020 } 1021 1022 static int 1023 cache_zap_wlocked_bucket_kl(struct namecache *ncp, struct rwlock *blp, 1024 struct mtx **vlpp1, struct mtx **vlpp2) 1025 { 1026 struct mtx *dvlp, *vlp; 1027 1028 cache_assert_bucket_locked(ncp, RA_WLOCKED); 1029 1030 dvlp = VP2VNODELOCK(ncp->nc_dvp); 1031 vlp = NULL; 1032 if (!(ncp->nc_flag & NCF_NEGATIVE)) 1033 vlp = VP2VNODELOCK(ncp->nc_vp); 1034 cache_sort(&dvlp, &vlp); 1035 1036 if (*vlpp1 == dvlp && *vlpp2 == vlp) { 1037 cache_zap_locked(ncp, false); 1038 cache_unlock_vnodes(dvlp, vlp); 1039 *vlpp1 = NULL; 1040 *vlpp2 = NULL; 1041 return (0); 1042 } 1043 1044 if (*vlpp1 != NULL) 1045 mtx_unlock(*vlpp1); 1046 if (*vlpp2 != NULL) 1047 mtx_unlock(*vlpp2); 1048 *vlpp1 = NULL; 1049 *vlpp2 = NULL; 1050 1051 if (cache_trylock_vnodes(dvlp, vlp) == 0) { 1052 cache_zap_locked(ncp, false); 1053 cache_unlock_vnodes(dvlp, vlp); 1054 return (0); 1055 } 1056 1057 rw_wunlock(blp); 1058 *vlpp1 = dvlp; 1059 *vlpp2 = vlp; 1060 if (*vlpp1 != NULL) 1061 mtx_lock(*vlpp1); 1062 mtx_lock(*vlpp2); 1063 rw_wlock(blp); 1064 return (EAGAIN); 1065 } 1066 1067 static void 1068 cache_lookup_unlock(struct rwlock *blp, struct mtx *vlp) 1069 { 1070 1071 if (blp != NULL) { 1072 rw_runlock(blp); 1073 mtx_assert(vlp, MA_NOTOWNED); 1074 } else { 1075 mtx_unlock(vlp); 1076 } 1077 } 1078 1079 /* 1080 * Lookup an entry in the cache 1081 * 1082 * Lookup is called with dvp pointing to the directory to search, 1083 * cnp pointing to the name of the entry being sought. If the lookup 1084 * succeeds, the vnode is returned in *vpp, and a status of -1 is 1085 * returned. If the lookup determines that the name does not exist 1086 * (negative caching), a status of ENOENT is returned. If the lookup 1087 * fails, a status of zero is returned. If the directory vnode is 1088 * recycled out from under us due to a forced unmount, a status of 1089 * ENOENT is returned. 1090 * 1091 * vpp is locked and ref'd on return. If we're looking up DOTDOT, dvp is 1092 * unlocked. If we're looking up . an extra ref is taken, but the lock is 1093 * not recursively acquired. 1094 */ 1095 1096 int 1097 cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, 1098 struct timespec *tsp, int *ticksp) 1099 { 1100 struct namecache *ncp; 1101 struct rwlock *blp; 1102 struct mtx *dvlp, *dvlp2; 1103 uint32_t hash; 1104 int error, ltype; 1105 1106 if (__predict_false(!doingcache)) { 1107 cnp->cn_flags &= ~MAKEENTRY; 1108 return (0); 1109 } 1110 retry: 1111 blp = NULL; 1112 dvlp = VP2VNODELOCK(dvp); 1113 error = 0; 1114 counter_u64_add(numcalls, 1); 1115 1116 if (cnp->cn_nameptr[0] == '.') { 1117 if (cnp->cn_namelen == 1) { 1118 *vpp = dvp; 1119 CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .", 1120 dvp, cnp->cn_nameptr); 1121 counter_u64_add(dothits, 1); 1122 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ".", *vpp); 1123 if (tsp != NULL) 1124 timespecclear(tsp); 1125 if (ticksp != NULL) 1126 *ticksp = ticks; 1127 vrefact(*vpp); 1128 /* 1129 * When we lookup "." we still can be asked to lock it 1130 * differently... 1131 */ 1132 ltype = cnp->cn_lkflags & LK_TYPE_MASK; 1133 if (ltype != VOP_ISLOCKED(*vpp)) { 1134 if (ltype == LK_EXCLUSIVE) { 1135 vn_lock(*vpp, LK_UPGRADE | LK_RETRY); 1136 if ((*vpp)->v_iflag & VI_DOOMED) { 1137 /* forced unmount */ 1138 vrele(*vpp); 1139 *vpp = NULL; 1140 return (ENOENT); 1141 } 1142 } else 1143 vn_lock(*vpp, LK_DOWNGRADE | LK_RETRY); 1144 } 1145 return (-1); 1146 } 1147 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 1148 counter_u64_add(dotdothits, 1); 1149 dvlp2 = NULL; 1150 mtx_lock(dvlp); 1151 retry_dotdot: 1152 ncp = dvp->v_cache_dd; 1153 if (ncp == NULL) { 1154 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, 1155 "..", NULL); 1156 mtx_unlock(dvlp); 1157 return (0); 1158 } 1159 if ((cnp->cn_flags & MAKEENTRY) == 0) { 1160 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) { 1161 if (ncp->nc_dvp != dvp) 1162 panic("dvp %p v_cache_dd %p\n", dvp, ncp); 1163 if (!cache_zap_locked_vnode_kl2(ncp, 1164 dvp, &dvlp2)) 1165 goto retry_dotdot; 1166 MPASS(dvp->v_cache_dd == NULL); 1167 mtx_unlock(dvlp); 1168 if (dvlp2 != NULL) 1169 mtx_unlock(dvlp2); 1170 cache_free(ncp); 1171 } else { 1172 dvp->v_cache_dd = NULL; 1173 mtx_unlock(dvlp); 1174 if (dvlp2 != NULL) 1175 mtx_unlock(dvlp2); 1176 } 1177 return (0); 1178 } 1179 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) { 1180 if (ncp->nc_flag & NCF_NEGATIVE) 1181 *vpp = NULL; 1182 else 1183 *vpp = ncp->nc_vp; 1184 } else 1185 *vpp = ncp->nc_dvp; 1186 /* Return failure if negative entry was found. */ 1187 if (*vpp == NULL) 1188 goto negative_success; 1189 CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..", 1190 dvp, cnp->cn_nameptr, *vpp); 1191 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, "..", 1192 *vpp); 1193 cache_out_ts(ncp, tsp, ticksp); 1194 if ((ncp->nc_flag & (NCF_ISDOTDOT | NCF_DTS)) == 1195 NCF_DTS && tsp != NULL) 1196 *tsp = ((struct namecache_ts *)ncp)-> 1197 nc_dotdottime; 1198 goto success; 1199 } 1200 } 1201 1202 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp); 1203 blp = HASH2BUCKETLOCK(hash); 1204 rw_rlock(blp); 1205 1206 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 1207 counter_u64_add(numchecks, 1); 1208 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 1209 !bcmp(nc_get_name(ncp), cnp->cn_nameptr, ncp->nc_nlen)) 1210 break; 1211 } 1212 1213 /* We failed to find an entry */ 1214 if (ncp == NULL) { 1215 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr, 1216 NULL); 1217 if ((cnp->cn_flags & MAKEENTRY) == 0) { 1218 counter_u64_add(nummisszap, 1); 1219 } else { 1220 counter_u64_add(nummiss, 1); 1221 } 1222 goto unlock; 1223 } 1224 1225 /* We don't want to have an entry, so dump it */ 1226 if ((cnp->cn_flags & MAKEENTRY) == 0) { 1227 counter_u64_add(numposzaps, 1); 1228 goto zap_and_exit; 1229 } 1230 1231 /* We found a "positive" match, return the vnode */ 1232 if (!(ncp->nc_flag & NCF_NEGATIVE)) { 1233 counter_u64_add(numposhits, 1); 1234 *vpp = ncp->nc_vp; 1235 CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p", 1236 dvp, cnp->cn_nameptr, *vpp, ncp); 1237 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, nc_get_name(ncp), 1238 *vpp); 1239 cache_out_ts(ncp, tsp, ticksp); 1240 goto success; 1241 } 1242 1243 negative_success: 1244 /* We found a negative match, and want to create it, so purge */ 1245 if (cnp->cn_nameiop == CREATE) { 1246 counter_u64_add(numnegzaps, 1); 1247 goto zap_and_exit; 1248 } 1249 1250 counter_u64_add(numneghits, 1); 1251 cache_negative_hit(ncp); 1252 if (ncp->nc_flag & NCF_WHITE) 1253 cnp->cn_flags |= ISWHITEOUT; 1254 SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp, 1255 nc_get_name(ncp)); 1256 cache_out_ts(ncp, tsp, ticksp); 1257 cache_lookup_unlock(blp, dvlp); 1258 return (ENOENT); 1259 1260 success: 1261 /* 1262 * On success we return a locked and ref'd vnode as per the lookup 1263 * protocol. 1264 */ 1265 MPASS(dvp != *vpp); 1266 ltype = 0; /* silence gcc warning */ 1267 if (cnp->cn_flags & ISDOTDOT) { 1268 ltype = VOP_ISLOCKED(dvp); 1269 VOP_UNLOCK(dvp, 0); 1270 } 1271 vhold(*vpp); 1272 cache_lookup_unlock(blp, dvlp); 1273 error = vget(*vpp, cnp->cn_lkflags | LK_VNHELD, cnp->cn_thread); 1274 if (cnp->cn_flags & ISDOTDOT) { 1275 vn_lock(dvp, ltype | LK_RETRY); 1276 if (dvp->v_iflag & VI_DOOMED) { 1277 if (error == 0) 1278 vput(*vpp); 1279 *vpp = NULL; 1280 return (ENOENT); 1281 } 1282 } 1283 if (error) { 1284 *vpp = NULL; 1285 goto retry; 1286 } 1287 if ((cnp->cn_flags & ISLASTCN) && 1288 (cnp->cn_lkflags & LK_TYPE_MASK) == LK_EXCLUSIVE) { 1289 ASSERT_VOP_ELOCKED(*vpp, "cache_lookup"); 1290 } 1291 return (-1); 1292 1293 unlock: 1294 cache_lookup_unlock(blp, dvlp); 1295 return (0); 1296 1297 zap_and_exit: 1298 if (blp != NULL) 1299 error = cache_zap_rlocked_bucket(ncp, blp); 1300 else 1301 error = cache_zap_locked_vnode(ncp, dvp); 1302 if (error != 0) { 1303 zap_and_exit_bucket_fail++; 1304 cache_maybe_yield(); 1305 goto retry; 1306 } 1307 cache_free(ncp); 1308 return (0); 1309 } 1310 1311 struct celockstate { 1312 struct mtx *vlp[3]; 1313 struct rwlock *blp[2]; 1314 }; 1315 CTASSERT((nitems(((struct celockstate *)0)->vlp) == 3)); 1316 CTASSERT((nitems(((struct celockstate *)0)->blp) == 2)); 1317 1318 static inline void 1319 cache_celockstate_init(struct celockstate *cel) 1320 { 1321 1322 bzero(cel, sizeof(*cel)); 1323 } 1324 1325 static void 1326 cache_lock_vnodes_cel(struct celockstate *cel, struct vnode *vp, 1327 struct vnode *dvp) 1328 { 1329 struct mtx *vlp1, *vlp2; 1330 1331 MPASS(cel->vlp[0] == NULL); 1332 MPASS(cel->vlp[1] == NULL); 1333 MPASS(cel->vlp[2] == NULL); 1334 1335 MPASS(vp != NULL || dvp != NULL); 1336 1337 vlp1 = VP2VNODELOCK(vp); 1338 vlp2 = VP2VNODELOCK(dvp); 1339 cache_sort(&vlp1, &vlp2); 1340 1341 if (vlp1 != NULL) { 1342 mtx_lock(vlp1); 1343 cel->vlp[0] = vlp1; 1344 } 1345 mtx_lock(vlp2); 1346 cel->vlp[1] = vlp2; 1347 } 1348 1349 static void 1350 cache_unlock_vnodes_cel(struct celockstate *cel) 1351 { 1352 1353 MPASS(cel->vlp[0] != NULL || cel->vlp[1] != NULL); 1354 1355 if (cel->vlp[0] != NULL) 1356 mtx_unlock(cel->vlp[0]); 1357 if (cel->vlp[1] != NULL) 1358 mtx_unlock(cel->vlp[1]); 1359 if (cel->vlp[2] != NULL) 1360 mtx_unlock(cel->vlp[2]); 1361 } 1362 1363 static bool 1364 cache_lock_vnodes_cel_3(struct celockstate *cel, struct vnode *vp) 1365 { 1366 struct mtx *vlp; 1367 bool ret; 1368 1369 cache_assert_vlp_locked(cel->vlp[0]); 1370 cache_assert_vlp_locked(cel->vlp[1]); 1371 MPASS(cel->vlp[2] == NULL); 1372 1373 MPASS(vp != NULL); 1374 vlp = VP2VNODELOCK(vp); 1375 1376 ret = true; 1377 if (vlp >= cel->vlp[1]) { 1378 mtx_lock(vlp); 1379 } else { 1380 if (mtx_trylock(vlp)) 1381 goto out; 1382 cache_lock_vnodes_cel_3_failures++; 1383 cache_unlock_vnodes_cel(cel); 1384 if (vlp < cel->vlp[0]) { 1385 mtx_lock(vlp); 1386 mtx_lock(cel->vlp[0]); 1387 mtx_lock(cel->vlp[1]); 1388 } else { 1389 if (cel->vlp[0] != NULL) 1390 mtx_lock(cel->vlp[0]); 1391 mtx_lock(vlp); 1392 mtx_lock(cel->vlp[1]); 1393 } 1394 ret = false; 1395 } 1396 out: 1397 cel->vlp[2] = vlp; 1398 return (ret); 1399 } 1400 1401 static void 1402 cache_lock_buckets_cel(struct celockstate *cel, struct rwlock *blp1, 1403 struct rwlock *blp2) 1404 { 1405 1406 MPASS(cel->blp[0] == NULL); 1407 MPASS(cel->blp[1] == NULL); 1408 1409 cache_sort(&blp1, &blp2); 1410 1411 if (blp1 != NULL) { 1412 rw_wlock(blp1); 1413 cel->blp[0] = blp1; 1414 } 1415 rw_wlock(blp2); 1416 cel->blp[1] = blp2; 1417 } 1418 1419 static void 1420 cache_unlock_buckets_cel(struct celockstate *cel) 1421 { 1422 1423 if (cel->blp[0] != NULL) 1424 rw_wunlock(cel->blp[0]); 1425 rw_wunlock(cel->blp[1]); 1426 } 1427 1428 /* 1429 * Lock part of the cache affected by the insertion. 1430 * 1431 * This means vnodelocks for dvp, vp and the relevant bucketlock. 1432 * However, insertion can result in removal of an old entry. In this 1433 * case we have an additional vnode and bucketlock pair to lock. If the 1434 * entry is negative, ncelock is locked instead of the vnode. 1435 * 1436 * That is, in the worst case we have to lock 3 vnodes and 2 bucketlocks, while 1437 * preserving the locking order (smaller address first). 1438 */ 1439 static void 1440 cache_enter_lock(struct celockstate *cel, struct vnode *dvp, struct vnode *vp, 1441 uint32_t hash) 1442 { 1443 struct namecache *ncp; 1444 struct rwlock *blps[2]; 1445 1446 blps[0] = HASH2BUCKETLOCK(hash); 1447 for (;;) { 1448 blps[1] = NULL; 1449 cache_lock_vnodes_cel(cel, dvp, vp); 1450 if (vp == NULL || vp->v_type != VDIR) 1451 break; 1452 ncp = vp->v_cache_dd; 1453 if (ncp == NULL) 1454 break; 1455 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 1456 break; 1457 MPASS(ncp->nc_dvp == vp); 1458 blps[1] = NCP2BUCKETLOCK(ncp); 1459 if (ncp->nc_flag & NCF_NEGATIVE) 1460 break; 1461 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp)) 1462 break; 1463 /* 1464 * All vnodes got re-locked. Re-validate the state and if 1465 * nothing changed we are done. Otherwise restart. 1466 */ 1467 if (ncp == vp->v_cache_dd && 1468 (ncp->nc_flag & NCF_ISDOTDOT) != 0 && 1469 blps[1] == NCP2BUCKETLOCK(ncp) && 1470 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2]) 1471 break; 1472 cache_unlock_vnodes_cel(cel); 1473 cel->vlp[0] = NULL; 1474 cel->vlp[1] = NULL; 1475 cel->vlp[2] = NULL; 1476 } 1477 cache_lock_buckets_cel(cel, blps[0], blps[1]); 1478 } 1479 1480 static void 1481 cache_enter_lock_dd(struct celockstate *cel, struct vnode *dvp, struct vnode *vp, 1482 uint32_t hash) 1483 { 1484 struct namecache *ncp; 1485 struct rwlock *blps[2]; 1486 1487 blps[0] = HASH2BUCKETLOCK(hash); 1488 for (;;) { 1489 blps[1] = NULL; 1490 cache_lock_vnodes_cel(cel, dvp, vp); 1491 ncp = dvp->v_cache_dd; 1492 if (ncp == NULL) 1493 break; 1494 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 1495 break; 1496 MPASS(ncp->nc_dvp == dvp); 1497 blps[1] = NCP2BUCKETLOCK(ncp); 1498 if (ncp->nc_flag & NCF_NEGATIVE) 1499 break; 1500 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp)) 1501 break; 1502 if (ncp == dvp->v_cache_dd && 1503 (ncp->nc_flag & NCF_ISDOTDOT) != 0 && 1504 blps[1] == NCP2BUCKETLOCK(ncp) && 1505 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2]) 1506 break; 1507 cache_unlock_vnodes_cel(cel); 1508 cel->vlp[0] = NULL; 1509 cel->vlp[1] = NULL; 1510 cel->vlp[2] = NULL; 1511 } 1512 cache_lock_buckets_cel(cel, blps[0], blps[1]); 1513 } 1514 1515 static void 1516 cache_enter_unlock(struct celockstate *cel) 1517 { 1518 1519 cache_unlock_buckets_cel(cel); 1520 cache_unlock_vnodes_cel(cel); 1521 } 1522 1523 /* 1524 * Add an entry to the cache. 1525 */ 1526 void 1527 cache_enter_time(struct vnode *dvp, struct vnode *vp, struct componentname *cnp, 1528 struct timespec *tsp, struct timespec *dtsp) 1529 { 1530 struct celockstate cel; 1531 struct namecache *ncp, *n2, *ndd; 1532 struct namecache_ts *n3; 1533 struct nchashhead *ncpp; 1534 struct neglist *neglist; 1535 uint32_t hash; 1536 int flag; 1537 int len; 1538 bool neg_locked; 1539 1540 CTR3(KTR_VFS, "cache_enter(%p, %p, %s)", dvp, vp, cnp->cn_nameptr); 1541 VNASSERT(vp == NULL || (vp->v_iflag & VI_DOOMED) == 0, vp, 1542 ("cache_enter: Adding a doomed vnode")); 1543 VNASSERT(dvp == NULL || (dvp->v_iflag & VI_DOOMED) == 0, dvp, 1544 ("cache_enter: Doomed vnode used as src")); 1545 1546 if (__predict_false(!doingcache)) 1547 return; 1548 1549 /* 1550 * Avoid blowout in namecache entries. 1551 */ 1552 if (__predict_false(numcache >= desiredvnodes * ncsizefactor)) 1553 return; 1554 1555 cache_celockstate_init(&cel); 1556 ndd = NULL; 1557 flag = 0; 1558 if (cnp->cn_nameptr[0] == '.') { 1559 if (cnp->cn_namelen == 1) 1560 return; 1561 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 1562 len = cnp->cn_namelen; 1563 hash = cache_get_hash(cnp->cn_nameptr, len, dvp); 1564 cache_enter_lock_dd(&cel, dvp, vp, hash); 1565 /* 1566 * If dotdot entry already exists, just retarget it 1567 * to new parent vnode, otherwise continue with new 1568 * namecache entry allocation. 1569 */ 1570 if ((ncp = dvp->v_cache_dd) != NULL && 1571 ncp->nc_flag & NCF_ISDOTDOT) { 1572 KASSERT(ncp->nc_dvp == dvp, 1573 ("wrong isdotdot parent")); 1574 neg_locked = false; 1575 if (ncp->nc_flag & NCF_NEGATIVE || vp == NULL) { 1576 neglist = NCP2NEGLIST(ncp); 1577 mtx_lock(&ncneg_hot.nl_lock); 1578 mtx_lock(&neglist->nl_lock); 1579 neg_locked = true; 1580 } 1581 if (!(ncp->nc_flag & NCF_NEGATIVE)) { 1582 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, 1583 ncp, nc_dst); 1584 } else { 1585 cache_negative_remove(ncp, true); 1586 } 1587 if (vp != NULL) { 1588 TAILQ_INSERT_HEAD(&vp->v_cache_dst, 1589 ncp, nc_dst); 1590 ncp->nc_flag &= ~(NCF_NEGATIVE|NCF_HOTNEGATIVE); 1591 } else { 1592 ncp->nc_flag &= ~(NCF_HOTNEGATIVE); 1593 ncp->nc_flag |= NCF_NEGATIVE; 1594 cache_negative_insert(ncp, true); 1595 } 1596 if (neg_locked) { 1597 mtx_unlock(&neglist->nl_lock); 1598 mtx_unlock(&ncneg_hot.nl_lock); 1599 } 1600 ncp->nc_vp = vp; 1601 cache_enter_unlock(&cel); 1602 return; 1603 } 1604 dvp->v_cache_dd = NULL; 1605 cache_enter_unlock(&cel); 1606 cache_celockstate_init(&cel); 1607 SDT_PROBE3(vfs, namecache, enter, done, dvp, "..", vp); 1608 flag = NCF_ISDOTDOT; 1609 } 1610 } 1611 1612 /* 1613 * Calculate the hash key and setup as much of the new 1614 * namecache entry as possible before acquiring the lock. 1615 */ 1616 ncp = cache_alloc(cnp->cn_namelen, tsp != NULL); 1617 ncp->nc_flag = flag; 1618 ncp->nc_vp = vp; 1619 if (vp == NULL) 1620 ncp->nc_flag |= NCF_NEGATIVE; 1621 ncp->nc_dvp = dvp; 1622 if (tsp != NULL) { 1623 n3 = (struct namecache_ts *)ncp; 1624 n3->nc_time = *tsp; 1625 n3->nc_ticks = ticks; 1626 n3->nc_flag |= NCF_TS; 1627 if (dtsp != NULL) { 1628 n3->nc_dotdottime = *dtsp; 1629 n3->nc_flag |= NCF_DTS; 1630 } 1631 } 1632 len = ncp->nc_nlen = cnp->cn_namelen; 1633 hash = cache_get_hash(cnp->cn_nameptr, len, dvp); 1634 strlcpy(nc_get_name(ncp), cnp->cn_nameptr, len + 1); 1635 cache_enter_lock(&cel, dvp, vp, hash); 1636 1637 /* 1638 * See if this vnode or negative entry is already in the cache 1639 * with this name. This can happen with concurrent lookups of 1640 * the same path name. 1641 */ 1642 ncpp = NCHHASH(hash); 1643 LIST_FOREACH(n2, ncpp, nc_hash) { 1644 if (n2->nc_dvp == dvp && 1645 n2->nc_nlen == cnp->cn_namelen && 1646 !bcmp(nc_get_name(n2), cnp->cn_nameptr, n2->nc_nlen)) { 1647 if (tsp != NULL) { 1648 KASSERT((n2->nc_flag & NCF_TS) != 0, 1649 ("no NCF_TS")); 1650 n3 = (struct namecache_ts *)n2; 1651 n3->nc_time = 1652 ((struct namecache_ts *)ncp)->nc_time; 1653 n3->nc_ticks = 1654 ((struct namecache_ts *)ncp)->nc_ticks; 1655 if (dtsp != NULL) { 1656 n3->nc_dotdottime = 1657 ((struct namecache_ts *)ncp)-> 1658 nc_dotdottime; 1659 if (ncp->nc_flag & NCF_NEGATIVE) 1660 mtx_lock(&ncneg_hot.nl_lock); 1661 n3->nc_flag |= NCF_DTS; 1662 if (ncp->nc_flag & NCF_NEGATIVE) 1663 mtx_unlock(&ncneg_hot.nl_lock); 1664 } 1665 } 1666 goto out_unlock_free; 1667 } 1668 } 1669 1670 if (flag == NCF_ISDOTDOT) { 1671 /* 1672 * See if we are trying to add .. entry, but some other lookup 1673 * has populated v_cache_dd pointer already. 1674 */ 1675 if (dvp->v_cache_dd != NULL) 1676 goto out_unlock_free; 1677 KASSERT(vp == NULL || vp->v_type == VDIR, 1678 ("wrong vnode type %p", vp)); 1679 dvp->v_cache_dd = ncp; 1680 } 1681 1682 atomic_add_rel_long(&numcache, 1); 1683 if (vp != NULL) { 1684 if (vp->v_type == VDIR) { 1685 if (flag != NCF_ISDOTDOT) { 1686 /* 1687 * For this case, the cache entry maps both the 1688 * directory name in it and the name ".." for the 1689 * directory's parent. 1690 */ 1691 if ((ndd = vp->v_cache_dd) != NULL) { 1692 if ((ndd->nc_flag & NCF_ISDOTDOT) != 0) 1693 cache_zap_locked(ndd, false); 1694 else 1695 ndd = NULL; 1696 } 1697 vp->v_cache_dd = ncp; 1698 } 1699 } else { 1700 vp->v_cache_dd = NULL; 1701 } 1702 } 1703 1704 if (flag != NCF_ISDOTDOT) { 1705 if (LIST_EMPTY(&dvp->v_cache_src)) { 1706 vhold(dvp); 1707 atomic_add_rel_long(&numcachehv, 1); 1708 } 1709 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); 1710 } 1711 1712 /* 1713 * Insert the new namecache entry into the appropriate chain 1714 * within the cache entries table. 1715 */ 1716 LIST_INSERT_HEAD(ncpp, ncp, nc_hash); 1717 1718 /* 1719 * If the entry is "negative", we place it into the 1720 * "negative" cache queue, otherwise, we place it into the 1721 * destination vnode's cache entries queue. 1722 */ 1723 if (vp != NULL) { 1724 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); 1725 SDT_PROBE3(vfs, namecache, enter, done, dvp, nc_get_name(ncp), 1726 vp); 1727 } else { 1728 if (cnp->cn_flags & ISWHITEOUT) 1729 ncp->nc_flag |= NCF_WHITE; 1730 cache_negative_insert(ncp, false); 1731 SDT_PROBE2(vfs, namecache, enter_negative, done, dvp, 1732 nc_get_name(ncp)); 1733 } 1734 cache_enter_unlock(&cel); 1735 if (numneg * ncnegfactor > numcache) 1736 cache_negative_zap_one(); 1737 cache_free(ndd); 1738 return; 1739 out_unlock_free: 1740 cache_enter_unlock(&cel); 1741 cache_free(ncp); 1742 return; 1743 } 1744 1745 static u_int 1746 cache_roundup_2(u_int val) 1747 { 1748 u_int res; 1749 1750 for (res = 1; res <= val; res <<= 1) 1751 continue; 1752 1753 return (res); 1754 } 1755 1756 /* 1757 * Name cache initialization, from vfs_init() when we are booting 1758 */ 1759 static void 1760 nchinit(void *dummy __unused) 1761 { 1762 u_int i; 1763 1764 cache_zone_small = uma_zcreate("S VFS Cache", 1765 sizeof(struct namecache) + CACHE_PATH_CUTOFF + 1, 1766 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 1767 cache_zone_small_ts = uma_zcreate("STS VFS Cache", 1768 sizeof(struct namecache_ts) + CACHE_PATH_CUTOFF + 1, 1769 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 1770 cache_zone_large = uma_zcreate("L VFS Cache", 1771 sizeof(struct namecache) + NAME_MAX + 1, 1772 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 1773 cache_zone_large_ts = uma_zcreate("LTS VFS Cache", 1774 sizeof(struct namecache_ts) + NAME_MAX + 1, 1775 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 1776 1777 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash); 1778 ncbuckethash = cache_roundup_2(mp_ncpus * 64) - 1; 1779 if (ncbuckethash > nchash) 1780 ncbuckethash = nchash; 1781 bucketlocks = malloc(sizeof(*bucketlocks) * numbucketlocks, M_VFSCACHE, 1782 M_WAITOK | M_ZERO); 1783 for (i = 0; i < numbucketlocks; i++) 1784 rw_init_flags(&bucketlocks[i], "ncbuc", RW_DUPOK | RW_RECURSE); 1785 ncvnodehash = cache_roundup_2(mp_ncpus * 64) - 1; 1786 vnodelocks = malloc(sizeof(*vnodelocks) * numvnodelocks, M_VFSCACHE, 1787 M_WAITOK | M_ZERO); 1788 for (i = 0; i < numvnodelocks; i++) 1789 mtx_init(&vnodelocks[i], "ncvn", NULL, MTX_DUPOK | MTX_RECURSE); 1790 ncpurgeminvnodes = numbucketlocks; 1791 1792 ncneghash = 3; 1793 neglists = malloc(sizeof(*neglists) * numneglists, M_VFSCACHE, 1794 M_WAITOK | M_ZERO); 1795 for (i = 0; i < numneglists; i++) { 1796 mtx_init(&neglists[i].nl_lock, "ncnegl", NULL, MTX_DEF); 1797 TAILQ_INIT(&neglists[i].nl_list); 1798 } 1799 mtx_init(&ncneg_hot.nl_lock, "ncneglh", NULL, MTX_DEF); 1800 TAILQ_INIT(&ncneg_hot.nl_list); 1801 1802 mtx_init(&ncneg_shrink_lock, "ncnegs", NULL, MTX_DEF); 1803 1804 numcalls = counter_u64_alloc(M_WAITOK); 1805 dothits = counter_u64_alloc(M_WAITOK); 1806 dotdothits = counter_u64_alloc(M_WAITOK); 1807 numchecks = counter_u64_alloc(M_WAITOK); 1808 nummiss = counter_u64_alloc(M_WAITOK); 1809 nummisszap = counter_u64_alloc(M_WAITOK); 1810 numposzaps = counter_u64_alloc(M_WAITOK); 1811 numposhits = counter_u64_alloc(M_WAITOK); 1812 numnegzaps = counter_u64_alloc(M_WAITOK); 1813 numneghits = counter_u64_alloc(M_WAITOK); 1814 numfullpathcalls = counter_u64_alloc(M_WAITOK); 1815 numfullpathfail1 = counter_u64_alloc(M_WAITOK); 1816 numfullpathfail2 = counter_u64_alloc(M_WAITOK); 1817 numfullpathfail4 = counter_u64_alloc(M_WAITOK); 1818 numfullpathfound = counter_u64_alloc(M_WAITOK); 1819 } 1820 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL); 1821 1822 void 1823 cache_changesize(int newmaxvnodes) 1824 { 1825 struct nchashhead *new_nchashtbl, *old_nchashtbl; 1826 u_long new_nchash, old_nchash; 1827 struct namecache *ncp; 1828 uint32_t hash; 1829 int i; 1830 1831 newmaxvnodes = cache_roundup_2(newmaxvnodes * 2); 1832 if (newmaxvnodes < numbucketlocks) 1833 newmaxvnodes = numbucketlocks; 1834 1835 new_nchashtbl = hashinit(newmaxvnodes, M_VFSCACHE, &new_nchash); 1836 /* If same hash table size, nothing to do */ 1837 if (nchash == new_nchash) { 1838 free(new_nchashtbl, M_VFSCACHE); 1839 return; 1840 } 1841 /* 1842 * Move everything from the old hash table to the new table. 1843 * None of the namecache entries in the table can be removed 1844 * because to do so, they have to be removed from the hash table. 1845 */ 1846 cache_lock_all_vnodes(); 1847 cache_lock_all_buckets(); 1848 old_nchashtbl = nchashtbl; 1849 old_nchash = nchash; 1850 nchashtbl = new_nchashtbl; 1851 nchash = new_nchash; 1852 for (i = 0; i <= old_nchash; i++) { 1853 while ((ncp = LIST_FIRST(&old_nchashtbl[i])) != NULL) { 1854 hash = cache_get_hash(nc_get_name(ncp), ncp->nc_nlen, 1855 ncp->nc_dvp); 1856 LIST_REMOVE(ncp, nc_hash); 1857 LIST_INSERT_HEAD(NCHHASH(hash), ncp, nc_hash); 1858 } 1859 } 1860 cache_unlock_all_buckets(); 1861 cache_unlock_all_vnodes(); 1862 free(old_nchashtbl, M_VFSCACHE); 1863 } 1864 1865 /* 1866 * Invalidate all entries to a particular vnode. 1867 */ 1868 void 1869 cache_purge(struct vnode *vp) 1870 { 1871 TAILQ_HEAD(, namecache) ncps; 1872 struct namecache *ncp, *nnp; 1873 struct mtx *vlp, *vlp2; 1874 1875 CTR1(KTR_VFS, "cache_purge(%p)", vp); 1876 SDT_PROBE1(vfs, namecache, purge, done, vp); 1877 if (LIST_EMPTY(&vp->v_cache_src) && TAILQ_EMPTY(&vp->v_cache_dst) && 1878 vp->v_cache_dd == NULL) 1879 return; 1880 TAILQ_INIT(&ncps); 1881 vlp = VP2VNODELOCK(vp); 1882 vlp2 = NULL; 1883 mtx_lock(vlp); 1884 retry: 1885 while (!LIST_EMPTY(&vp->v_cache_src)) { 1886 ncp = LIST_FIRST(&vp->v_cache_src); 1887 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 1888 goto retry; 1889 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 1890 } 1891 while (!TAILQ_EMPTY(&vp->v_cache_dst)) { 1892 ncp = TAILQ_FIRST(&vp->v_cache_dst); 1893 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 1894 goto retry; 1895 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 1896 } 1897 ncp = vp->v_cache_dd; 1898 if (ncp != NULL) { 1899 KASSERT(ncp->nc_flag & NCF_ISDOTDOT, 1900 ("lost dotdot link")); 1901 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 1902 goto retry; 1903 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 1904 } 1905 KASSERT(vp->v_cache_dd == NULL, ("incomplete purge")); 1906 mtx_unlock(vlp); 1907 if (vlp2 != NULL) 1908 mtx_unlock(vlp2); 1909 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { 1910 cache_free(ncp); 1911 } 1912 } 1913 1914 /* 1915 * Invalidate all negative entries for a particular directory vnode. 1916 */ 1917 void 1918 cache_purge_negative(struct vnode *vp) 1919 { 1920 TAILQ_HEAD(, namecache) ncps; 1921 struct namecache *ncp, *nnp; 1922 struct mtx *vlp; 1923 1924 CTR1(KTR_VFS, "cache_purge_negative(%p)", vp); 1925 SDT_PROBE1(vfs, namecache, purge_negative, done, vp); 1926 TAILQ_INIT(&ncps); 1927 vlp = VP2VNODELOCK(vp); 1928 mtx_lock(vlp); 1929 LIST_FOREACH_SAFE(ncp, &vp->v_cache_src, nc_src, nnp) { 1930 if (!(ncp->nc_flag & NCF_NEGATIVE)) 1931 continue; 1932 cache_zap_negative_locked_vnode_kl(ncp, vp); 1933 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 1934 } 1935 mtx_unlock(vlp); 1936 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { 1937 cache_free(ncp); 1938 } 1939 } 1940 1941 /* 1942 * Flush all entries referencing a particular filesystem. 1943 */ 1944 void 1945 cache_purgevfs(struct mount *mp, bool force) 1946 { 1947 TAILQ_HEAD(, namecache) ncps; 1948 struct mtx *vlp1, *vlp2; 1949 struct rwlock *blp; 1950 struct nchashhead *bucket; 1951 struct namecache *ncp, *nnp; 1952 u_long i, j, n_nchash; 1953 int error; 1954 1955 /* Scan hash tables for applicable entries */ 1956 SDT_PROBE1(vfs, namecache, purgevfs, done, mp); 1957 if (!force && mp->mnt_nvnodelistsize <= ncpurgeminvnodes) 1958 return; 1959 TAILQ_INIT(&ncps); 1960 n_nchash = nchash + 1; 1961 vlp1 = vlp2 = NULL; 1962 for (i = 0; i < numbucketlocks; i++) { 1963 blp = (struct rwlock *)&bucketlocks[i]; 1964 rw_wlock(blp); 1965 for (j = i; j < n_nchash; j += numbucketlocks) { 1966 retry: 1967 bucket = &nchashtbl[j]; 1968 LIST_FOREACH_SAFE(ncp, bucket, nc_hash, nnp) { 1969 cache_assert_bucket_locked(ncp, RA_WLOCKED); 1970 if (ncp->nc_dvp->v_mount != mp) 1971 continue; 1972 error = cache_zap_wlocked_bucket_kl(ncp, blp, 1973 &vlp1, &vlp2); 1974 if (error != 0) 1975 goto retry; 1976 TAILQ_INSERT_HEAD(&ncps, ncp, nc_dst); 1977 } 1978 } 1979 rw_wunlock(blp); 1980 if (vlp1 == NULL && vlp2 == NULL) 1981 cache_maybe_yield(); 1982 } 1983 if (vlp1 != NULL) 1984 mtx_unlock(vlp1); 1985 if (vlp2 != NULL) 1986 mtx_unlock(vlp2); 1987 1988 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { 1989 cache_free(ncp); 1990 } 1991 } 1992 1993 /* 1994 * Perform canonical checks and cache lookup and pass on to filesystem 1995 * through the vop_cachedlookup only if needed. 1996 */ 1997 1998 int 1999 vfs_cache_lookup(struct vop_lookup_args *ap) 2000 { 2001 struct vnode *dvp; 2002 int error; 2003 struct vnode **vpp = ap->a_vpp; 2004 struct componentname *cnp = ap->a_cnp; 2005 struct ucred *cred = cnp->cn_cred; 2006 int flags = cnp->cn_flags; 2007 struct thread *td = cnp->cn_thread; 2008 2009 *vpp = NULL; 2010 dvp = ap->a_dvp; 2011 2012 if (dvp->v_type != VDIR) 2013 return (ENOTDIR); 2014 2015 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && 2016 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 2017 return (EROFS); 2018 2019 error = VOP_ACCESS(dvp, VEXEC, cred, td); 2020 if (error) 2021 return (error); 2022 2023 error = cache_lookup(dvp, vpp, cnp, NULL, NULL); 2024 if (error == 0) 2025 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); 2026 if (error == -1) 2027 return (0); 2028 return (error); 2029 } 2030 2031 /* 2032 * XXX All of these sysctls would probably be more productive dead. 2033 */ 2034 static int __read_mostly disablecwd; 2035 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, 2036 "Disable the getcwd syscall"); 2037 2038 /* Implementation of the getcwd syscall. */ 2039 int 2040 sys___getcwd(struct thread *td, struct __getcwd_args *uap) 2041 { 2042 2043 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen, 2044 MAXPATHLEN)); 2045 } 2046 2047 int 2048 kern___getcwd(struct thread *td, char *buf, enum uio_seg bufseg, u_int buflen, 2049 u_int path_max) 2050 { 2051 char *bp, *tmpbuf; 2052 struct filedesc *fdp; 2053 struct vnode *cdir, *rdir; 2054 int error; 2055 2056 if (__predict_false(disablecwd)) 2057 return (ENODEV); 2058 if (__predict_false(buflen < 2)) 2059 return (EINVAL); 2060 if (buflen > path_max) 2061 buflen = path_max; 2062 2063 tmpbuf = malloc(buflen, M_TEMP, M_WAITOK); 2064 fdp = td->td_proc->p_fd; 2065 FILEDESC_SLOCK(fdp); 2066 cdir = fdp->fd_cdir; 2067 vrefact(cdir); 2068 rdir = fdp->fd_rdir; 2069 vrefact(rdir); 2070 FILEDESC_SUNLOCK(fdp); 2071 error = vn_fullpath1(td, cdir, rdir, tmpbuf, &bp, buflen); 2072 vrele(rdir); 2073 vrele(cdir); 2074 2075 if (!error) { 2076 if (bufseg == UIO_SYSSPACE) 2077 bcopy(bp, buf, strlen(bp) + 1); 2078 else 2079 error = copyout(bp, buf, strlen(bp) + 1); 2080 #ifdef KTRACE 2081 if (KTRPOINT(curthread, KTR_NAMEI)) 2082 ktrnamei(bp); 2083 #endif 2084 } 2085 free(tmpbuf, M_TEMP); 2086 return (error); 2087 } 2088 2089 /* 2090 * Thus begins the fullpath magic. 2091 */ 2092 2093 static int __read_mostly disablefullpath; 2094 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0, 2095 "Disable the vn_fullpath function"); 2096 2097 /* 2098 * Retrieve the full filesystem path that correspond to a vnode from the name 2099 * cache (if available) 2100 */ 2101 int 2102 vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf) 2103 { 2104 char *buf; 2105 struct filedesc *fdp; 2106 struct vnode *rdir; 2107 int error; 2108 2109 if (__predict_false(disablefullpath)) 2110 return (ENODEV); 2111 if (__predict_false(vn == NULL)) 2112 return (EINVAL); 2113 2114 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 2115 fdp = td->td_proc->p_fd; 2116 FILEDESC_SLOCK(fdp); 2117 rdir = fdp->fd_rdir; 2118 vrefact(rdir); 2119 FILEDESC_SUNLOCK(fdp); 2120 error = vn_fullpath1(td, vn, rdir, buf, retbuf, MAXPATHLEN); 2121 vrele(rdir); 2122 2123 if (!error) 2124 *freebuf = buf; 2125 else 2126 free(buf, M_TEMP); 2127 return (error); 2128 } 2129 2130 /* 2131 * This function is similar to vn_fullpath, but it attempts to lookup the 2132 * pathname relative to the global root mount point. This is required for the 2133 * auditing sub-system, as audited pathnames must be absolute, relative to the 2134 * global root mount point. 2135 */ 2136 int 2137 vn_fullpath_global(struct thread *td, struct vnode *vn, 2138 char **retbuf, char **freebuf) 2139 { 2140 char *buf; 2141 int error; 2142 2143 if (__predict_false(disablefullpath)) 2144 return (ENODEV); 2145 if (__predict_false(vn == NULL)) 2146 return (EINVAL); 2147 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 2148 error = vn_fullpath1(td, vn, rootvnode, buf, retbuf, MAXPATHLEN); 2149 if (!error) 2150 *freebuf = buf; 2151 else 2152 free(buf, M_TEMP); 2153 return (error); 2154 } 2155 2156 int 2157 vn_vptocnp(struct vnode **vp, struct ucred *cred, char *buf, u_int *buflen) 2158 { 2159 struct vnode *dvp; 2160 struct namecache *ncp; 2161 struct mtx *vlp; 2162 int error; 2163 2164 vlp = VP2VNODELOCK(*vp); 2165 mtx_lock(vlp); 2166 TAILQ_FOREACH(ncp, &((*vp)->v_cache_dst), nc_dst) { 2167 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 2168 break; 2169 } 2170 if (ncp != NULL) { 2171 if (*buflen < ncp->nc_nlen) { 2172 mtx_unlock(vlp); 2173 vrele(*vp); 2174 counter_u64_add(numfullpathfail4, 1); 2175 error = ENOMEM; 2176 SDT_PROBE3(vfs, namecache, fullpath, return, error, 2177 vp, NULL); 2178 return (error); 2179 } 2180 *buflen -= ncp->nc_nlen; 2181 memcpy(buf + *buflen, nc_get_name(ncp), ncp->nc_nlen); 2182 SDT_PROBE3(vfs, namecache, fullpath, hit, ncp->nc_dvp, 2183 nc_get_name(ncp), vp); 2184 dvp = *vp; 2185 *vp = ncp->nc_dvp; 2186 vref(*vp); 2187 mtx_unlock(vlp); 2188 vrele(dvp); 2189 return (0); 2190 } 2191 SDT_PROBE1(vfs, namecache, fullpath, miss, vp); 2192 2193 mtx_unlock(vlp); 2194 vn_lock(*vp, LK_SHARED | LK_RETRY); 2195 error = VOP_VPTOCNP(*vp, &dvp, cred, buf, buflen); 2196 vput(*vp); 2197 if (error) { 2198 counter_u64_add(numfullpathfail2, 1); 2199 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); 2200 return (error); 2201 } 2202 2203 *vp = dvp; 2204 if (dvp->v_iflag & VI_DOOMED) { 2205 /* forced unmount */ 2206 vrele(dvp); 2207 error = ENOENT; 2208 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); 2209 return (error); 2210 } 2211 /* 2212 * *vp has its use count incremented still. 2213 */ 2214 2215 return (0); 2216 } 2217 2218 /* 2219 * The magic behind kern___getcwd() and vn_fullpath(). 2220 */ 2221 static int 2222 vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 2223 char *buf, char **retbuf, u_int buflen) 2224 { 2225 int error, slash_prefixed; 2226 #ifdef KDTRACE_HOOKS 2227 struct vnode *startvp = vp; 2228 #endif 2229 struct vnode *vp1; 2230 2231 buflen--; 2232 buf[buflen] = '\0'; 2233 error = 0; 2234 slash_prefixed = 0; 2235 2236 SDT_PROBE1(vfs, namecache, fullpath, entry, vp); 2237 counter_u64_add(numfullpathcalls, 1); 2238 vref(vp); 2239 if (vp->v_type != VDIR) { 2240 error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen); 2241 if (error) 2242 return (error); 2243 if (buflen == 0) { 2244 vrele(vp); 2245 return (ENOMEM); 2246 } 2247 buf[--buflen] = '/'; 2248 slash_prefixed = 1; 2249 } 2250 while (vp != rdir && vp != rootvnode) { 2251 /* 2252 * The vp vnode must be already fully constructed, 2253 * since it is either found in namecache or obtained 2254 * from VOP_VPTOCNP(). We may test for VV_ROOT safely 2255 * without obtaining the vnode lock. 2256 */ 2257 if ((vp->v_vflag & VV_ROOT) != 0) { 2258 vn_lock(vp, LK_RETRY | LK_SHARED); 2259 2260 /* 2261 * With the vnode locked, check for races with 2262 * unmount, forced or not. Note that we 2263 * already verified that vp is not equal to 2264 * the root vnode, which means that 2265 * mnt_vnodecovered can be NULL only for the 2266 * case of unmount. 2267 */ 2268 if ((vp->v_iflag & VI_DOOMED) != 0 || 2269 (vp1 = vp->v_mount->mnt_vnodecovered) == NULL || 2270 vp1->v_mountedhere != vp->v_mount) { 2271 vput(vp); 2272 error = ENOENT; 2273 SDT_PROBE3(vfs, namecache, fullpath, return, 2274 error, vp, NULL); 2275 break; 2276 } 2277 2278 vref(vp1); 2279 vput(vp); 2280 vp = vp1; 2281 continue; 2282 } 2283 if (vp->v_type != VDIR) { 2284 vrele(vp); 2285 counter_u64_add(numfullpathfail1, 1); 2286 error = ENOTDIR; 2287 SDT_PROBE3(vfs, namecache, fullpath, return, 2288 error, vp, NULL); 2289 break; 2290 } 2291 error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen); 2292 if (error) 2293 break; 2294 if (buflen == 0) { 2295 vrele(vp); 2296 error = ENOMEM; 2297 SDT_PROBE3(vfs, namecache, fullpath, return, error, 2298 startvp, NULL); 2299 break; 2300 } 2301 buf[--buflen] = '/'; 2302 slash_prefixed = 1; 2303 } 2304 if (error) 2305 return (error); 2306 if (!slash_prefixed) { 2307 if (buflen == 0) { 2308 vrele(vp); 2309 counter_u64_add(numfullpathfail4, 1); 2310 SDT_PROBE3(vfs, namecache, fullpath, return, ENOMEM, 2311 startvp, NULL); 2312 return (ENOMEM); 2313 } 2314 buf[--buflen] = '/'; 2315 } 2316 counter_u64_add(numfullpathfound, 1); 2317 vrele(vp); 2318 2319 SDT_PROBE3(vfs, namecache, fullpath, return, 0, startvp, buf + buflen); 2320 *retbuf = buf + buflen; 2321 return (0); 2322 } 2323 2324 struct vnode * 2325 vn_dir_dd_ino(struct vnode *vp) 2326 { 2327 struct namecache *ncp; 2328 struct vnode *ddvp; 2329 struct mtx *vlp; 2330 2331 ASSERT_VOP_LOCKED(vp, "vn_dir_dd_ino"); 2332 vlp = VP2VNODELOCK(vp); 2333 mtx_lock(vlp); 2334 TAILQ_FOREACH(ncp, &(vp->v_cache_dst), nc_dst) { 2335 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) 2336 continue; 2337 ddvp = ncp->nc_dvp; 2338 vhold(ddvp); 2339 mtx_unlock(vlp); 2340 if (vget(ddvp, LK_SHARED | LK_NOWAIT | LK_VNHELD, curthread)) 2341 return (NULL); 2342 return (ddvp); 2343 } 2344 mtx_unlock(vlp); 2345 return (NULL); 2346 } 2347 2348 int 2349 vn_commname(struct vnode *vp, char *buf, u_int buflen) 2350 { 2351 struct namecache *ncp; 2352 struct mtx *vlp; 2353 int l; 2354 2355 vlp = VP2VNODELOCK(vp); 2356 mtx_lock(vlp); 2357 TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst) 2358 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 2359 break; 2360 if (ncp == NULL) { 2361 mtx_unlock(vlp); 2362 return (ENOENT); 2363 } 2364 l = min(ncp->nc_nlen, buflen - 1); 2365 memcpy(buf, nc_get_name(ncp), l); 2366 mtx_unlock(vlp); 2367 buf[l] = '\0'; 2368 return (0); 2369 } 2370 2371 /* ABI compat shims for old kernel modules. */ 2372 #undef cache_enter 2373 2374 void cache_enter(struct vnode *dvp, struct vnode *vp, 2375 struct componentname *cnp); 2376 2377 void 2378 cache_enter(struct vnode *dvp, struct vnode *vp, struct componentname *cnp) 2379 { 2380 2381 cache_enter_time(dvp, vp, cnp, NULL, NULL); 2382 } 2383 2384 /* 2385 * This function updates path string to vnode's full global path 2386 * and checks the size of the new path string against the pathlen argument. 2387 * 2388 * Requires a locked, referenced vnode. 2389 * Vnode is re-locked on success or ENODEV, otherwise unlocked. 2390 * 2391 * If sysctl debug.disablefullpath is set, ENODEV is returned, 2392 * vnode is left locked and path remain untouched. 2393 * 2394 * If vp is a directory, the call to vn_fullpath_global() always succeeds 2395 * because it falls back to the ".." lookup if the namecache lookup fails. 2396 */ 2397 int 2398 vn_path_to_global_path(struct thread *td, struct vnode *vp, char *path, 2399 u_int pathlen) 2400 { 2401 struct nameidata nd; 2402 struct vnode *vp1; 2403 char *rpath, *fbuf; 2404 int error; 2405 2406 ASSERT_VOP_ELOCKED(vp, __func__); 2407 2408 /* Return ENODEV if sysctl debug.disablefullpath==1 */ 2409 if (__predict_false(disablefullpath)) 2410 return (ENODEV); 2411 2412 /* Construct global filesystem path from vp. */ 2413 VOP_UNLOCK(vp, 0); 2414 error = vn_fullpath_global(td, vp, &rpath, &fbuf); 2415 2416 if (error != 0) { 2417 vrele(vp); 2418 return (error); 2419 } 2420 2421 if (strlen(rpath) >= pathlen) { 2422 vrele(vp); 2423 error = ENAMETOOLONG; 2424 goto out; 2425 } 2426 2427 /* 2428 * Re-lookup the vnode by path to detect a possible rename. 2429 * As a side effect, the vnode is relocked. 2430 * If vnode was renamed, return ENOENT. 2431 */ 2432 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1, 2433 UIO_SYSSPACE, path, td); 2434 error = namei(&nd); 2435 if (error != 0) { 2436 vrele(vp); 2437 goto out; 2438 } 2439 NDFREE(&nd, NDF_ONLY_PNBUF); 2440 vp1 = nd.ni_vp; 2441 vrele(vp); 2442 if (vp1 == vp) 2443 strcpy(path, rpath); 2444 else { 2445 vput(vp1); 2446 error = ENOENT; 2447 } 2448 2449 out: 2450 free(fbuf, M_TEMP); 2451 return (error); 2452 } 2453