1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1989, 1993, 1995 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Poul-Henning Kamp of the FreeBSD Project. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)vfs_cache.c 8.5 (Berkeley) 3/22/95 35 */ 36 37 #include <sys/cdefs.h> 38 __FBSDID("$FreeBSD$"); 39 40 #include "opt_ktrace.h" 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/counter.h> 45 #include <sys/filedesc.h> 46 #include <sys/fnv_hash.h> 47 #include <sys/kernel.h> 48 #include <sys/lock.h> 49 #include <sys/malloc.h> 50 #include <sys/fcntl.h> 51 #include <sys/mount.h> 52 #include <sys/namei.h> 53 #include <sys/proc.h> 54 #include <sys/rwlock.h> 55 #include <sys/sdt.h> 56 #include <sys/smp.h> 57 #include <sys/syscallsubr.h> 58 #include <sys/sysctl.h> 59 #include <sys/sysproto.h> 60 #include <sys/vnode.h> 61 #ifdef KTRACE 62 #include <sys/ktrace.h> 63 #endif 64 65 #include <vm/uma.h> 66 67 SDT_PROVIDER_DECLARE(vfs); 68 SDT_PROBE_DEFINE3(vfs, namecache, enter, done, "struct vnode *", "char *", 69 "struct vnode *"); 70 SDT_PROBE_DEFINE2(vfs, namecache, enter_negative, done, "struct vnode *", 71 "char *"); 72 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, entry, "struct vnode *"); 73 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, hit, "struct vnode *", 74 "char *", "struct vnode *"); 75 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, miss, "struct vnode *"); 76 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, return, "int", 77 "struct vnode *", "char *"); 78 SDT_PROBE_DEFINE3(vfs, namecache, lookup, hit, "struct vnode *", "char *", 79 "struct vnode *"); 80 SDT_PROBE_DEFINE2(vfs, namecache, lookup, hit__negative, 81 "struct vnode *", "char *"); 82 SDT_PROBE_DEFINE2(vfs, namecache, lookup, miss, "struct vnode *", 83 "char *"); 84 SDT_PROBE_DEFINE1(vfs, namecache, purge, done, "struct vnode *"); 85 SDT_PROBE_DEFINE1(vfs, namecache, purge_negative, done, "struct vnode *"); 86 SDT_PROBE_DEFINE1(vfs, namecache, purgevfs, done, "struct mount *"); 87 SDT_PROBE_DEFINE3(vfs, namecache, zap, done, "struct vnode *", "char *", 88 "struct vnode *"); 89 SDT_PROBE_DEFINE3(vfs, namecache, zap_negative, done, "struct vnode *", 90 "char *", "int"); 91 SDT_PROBE_DEFINE3(vfs, namecache, shrink_negative, done, "struct vnode *", 92 "char *", "int"); 93 94 /* 95 * This structure describes the elements in the cache of recent 96 * names looked up by namei. 97 */ 98 99 struct namecache { 100 LIST_ENTRY(namecache) nc_hash; /* hash chain */ 101 LIST_ENTRY(namecache) nc_src; /* source vnode list */ 102 TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */ 103 struct vnode *nc_dvp; /* vnode of parent of name */ 104 union { 105 struct vnode *nu_vp; /* vnode the name refers to */ 106 u_int nu_neghits; /* negative entry hits */ 107 } n_un; 108 u_char nc_flag; /* flag bits */ 109 u_char nc_nlen; /* length of name */ 110 char nc_name[0]; /* segment name + nul */ 111 }; 112 113 /* 114 * struct namecache_ts repeats struct namecache layout up to the 115 * nc_nlen member. 116 * struct namecache_ts is used in place of struct namecache when time(s) need 117 * to be stored. The nc_dotdottime field is used when a cache entry is mapping 118 * both a non-dotdot directory name plus dotdot for the directory's 119 * parent. 120 */ 121 struct namecache_ts { 122 struct timespec nc_time; /* timespec provided by fs */ 123 struct timespec nc_dotdottime; /* dotdot timespec provided by fs */ 124 int nc_ticks; /* ticks value when entry was added */ 125 struct namecache nc_nc; 126 }; 127 128 #define nc_vp n_un.nu_vp 129 #define nc_neghits n_un.nu_neghits 130 131 /* 132 * Flags in namecache.nc_flag 133 */ 134 #define NCF_WHITE 0x01 135 #define NCF_ISDOTDOT 0x02 136 #define NCF_TS 0x04 137 #define NCF_DTS 0x08 138 #define NCF_DVDROP 0x10 139 #define NCF_NEGATIVE 0x20 140 #define NCF_HOTNEGATIVE 0x40 141 142 /* 143 * Name caching works as follows: 144 * 145 * Names found by directory scans are retained in a cache 146 * for future reference. It is managed LRU, so frequently 147 * used names will hang around. Cache is indexed by hash value 148 * obtained from (vp, name) where vp refers to the directory 149 * containing name. 150 * 151 * If it is a "negative" entry, (i.e. for a name that is known NOT to 152 * exist) the vnode pointer will be NULL. 153 * 154 * Upon reaching the last segment of a path, if the reference 155 * is for DELETE, or NOCACHE is set (rewrite), and the 156 * name is located in the cache, it will be dropped. 157 * 158 * These locks are used (in the order in which they can be taken): 159 * NAME TYPE ROLE 160 * vnodelock mtx vnode lists and v_cache_dd field protection 161 * bucketlock rwlock for access to given set of hash buckets 162 * neglist mtx negative entry LRU management 163 * 164 * Additionally, ncneg_shrink_lock mtx is used to have at most one thread 165 * shrinking the LRU list. 166 * 167 * It is legal to take multiple vnodelock and bucketlock locks. The locking 168 * order is lower address first. Both are recursive. 169 * 170 * "." lookups are lockless. 171 * 172 * ".." and vnode -> name lookups require vnodelock. 173 * 174 * name -> vnode lookup requires the relevant bucketlock to be held for reading. 175 * 176 * Insertions and removals of entries require involved vnodes and bucketlocks 177 * to be write-locked to prevent other threads from seeing the entry. 178 * 179 * Some lookups result in removal of the found entry (e.g. getting rid of a 180 * negative entry with the intent to create a positive one), which poses a 181 * problem when multiple threads reach the state. Similarly, two different 182 * threads can purge two different vnodes and try to remove the same name. 183 * 184 * If the already held vnode lock is lower than the second required lock, we 185 * can just take the other lock. However, in the opposite case, this could 186 * deadlock. As such, this is resolved by trylocking and if that fails unlocking 187 * the first node, locking everything in order and revalidating the state. 188 */ 189 190 /* 191 * Structures associated with name caching. 192 */ 193 #define NCHHASH(hash) \ 194 (&nchashtbl[(hash) & nchash]) 195 static __read_mostly LIST_HEAD(nchashhead, namecache) *nchashtbl;/* Hash Table */ 196 static u_long __read_mostly nchash; /* size of hash table */ 197 SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, 198 "Size of namecache hash table"); 199 static u_long __read_mostly ncnegfactor = 12; /* ratio of negative entries */ 200 SYSCTL_ULONG(_vfs, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, 201 "Ratio of negative namecache entries"); 202 static u_long __exclusive_cache_line numneg; /* number of negative entries allocated */ 203 SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, 204 "Number of negative entries in namecache"); 205 static u_long __exclusive_cache_line numcache;/* number of cache entries allocated */ 206 SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, 207 "Number of namecache entries"); 208 static u_long __exclusive_cache_line numcachehv;/* number of cache entries with vnodes held */ 209 SYSCTL_ULONG(_debug, OID_AUTO, numcachehv, CTLFLAG_RD, &numcachehv, 0, 210 "Number of namecache entries with vnodes held"); 211 u_int __read_mostly ncsizefactor = 2; 212 SYSCTL_UINT(_vfs, OID_AUTO, ncsizefactor, CTLFLAG_RW, &ncsizefactor, 0, 213 "Size factor for namecache"); 214 static u_int __read_mostly ncpurgeminvnodes; 215 SYSCTL_UINT(_vfs, OID_AUTO, ncpurgeminvnodes, CTLFLAG_RW, &ncpurgeminvnodes, 0, 216 "Number of vnodes below which purgevfs ignores the request"); 217 static u_int __read_mostly ncneghitsrequeue = 8; 218 SYSCTL_UINT(_vfs, OID_AUTO, ncneghitsrequeue, CTLFLAG_RW, &ncneghitsrequeue, 0, 219 "Number of hits to requeue a negative entry in the LRU list"); 220 221 struct nchstats nchstats; /* cache effectiveness statistics */ 222 223 static struct mtx ncneg_shrink_lock; 224 static int shrink_list_turn; 225 226 struct neglist { 227 struct mtx nl_lock; 228 TAILQ_HEAD(, namecache) nl_list; 229 } __aligned(CACHE_LINE_SIZE); 230 231 static struct neglist __read_mostly *neglists; 232 static struct neglist ncneg_hot; 233 234 #define numneglists (ncneghash + 1) 235 static u_int __read_mostly ncneghash; 236 static inline struct neglist * 237 NCP2NEGLIST(struct namecache *ncp) 238 { 239 240 return (&neglists[(((uintptr_t)(ncp) >> 8) & ncneghash)]); 241 } 242 243 #define numbucketlocks (ncbuckethash + 1) 244 static u_int __read_mostly ncbuckethash; 245 static struct rwlock_padalign __read_mostly *bucketlocks; 246 #define HASH2BUCKETLOCK(hash) \ 247 ((struct rwlock *)(&bucketlocks[((hash) & ncbuckethash)])) 248 249 #define numvnodelocks (ncvnodehash + 1) 250 static u_int __read_mostly ncvnodehash; 251 static struct mtx __read_mostly *vnodelocks; 252 static inline struct mtx * 253 VP2VNODELOCK(struct vnode *vp) 254 { 255 256 return (&vnodelocks[(((uintptr_t)(vp) >> 8) & ncvnodehash)]); 257 } 258 259 /* 260 * UMA zones for the VFS cache. 261 * 262 * The small cache is used for entries with short names, which are the 263 * most common. The large cache is used for entries which are too big to 264 * fit in the small cache. 265 */ 266 static uma_zone_t __read_mostly cache_zone_small; 267 static uma_zone_t __read_mostly cache_zone_small_ts; 268 static uma_zone_t __read_mostly cache_zone_large; 269 static uma_zone_t __read_mostly cache_zone_large_ts; 270 271 #define CACHE_PATH_CUTOFF 35 272 273 static struct namecache * 274 cache_alloc(int len, int ts) 275 { 276 struct namecache_ts *ncp_ts; 277 struct namecache *ncp; 278 279 if (__predict_false(ts)) { 280 if (len <= CACHE_PATH_CUTOFF) 281 ncp_ts = uma_zalloc(cache_zone_small_ts, M_WAITOK); 282 else 283 ncp_ts = uma_zalloc(cache_zone_large_ts, M_WAITOK); 284 ncp = &ncp_ts->nc_nc; 285 } else { 286 if (len <= CACHE_PATH_CUTOFF) 287 ncp = uma_zalloc(cache_zone_small, M_WAITOK); 288 else 289 ncp = uma_zalloc(cache_zone_large, M_WAITOK); 290 } 291 return (ncp); 292 } 293 294 static void 295 cache_free(struct namecache *ncp) 296 { 297 struct namecache_ts *ncp_ts; 298 299 if (ncp == NULL) 300 return; 301 if ((ncp->nc_flag & NCF_DVDROP) != 0) 302 vdrop(ncp->nc_dvp); 303 if (__predict_false(ncp->nc_flag & NCF_TS)) { 304 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); 305 if (ncp->nc_nlen <= CACHE_PATH_CUTOFF) 306 uma_zfree(cache_zone_small_ts, ncp_ts); 307 else 308 uma_zfree(cache_zone_large_ts, ncp_ts); 309 } else { 310 if (ncp->nc_nlen <= CACHE_PATH_CUTOFF) 311 uma_zfree(cache_zone_small, ncp); 312 else 313 uma_zfree(cache_zone_large, ncp); 314 } 315 } 316 317 static void 318 cache_out_ts(struct namecache *ncp, struct timespec *tsp, int *ticksp) 319 { 320 struct namecache_ts *ncp_ts; 321 322 KASSERT((ncp->nc_flag & NCF_TS) != 0 || 323 (tsp == NULL && ticksp == NULL), 324 ("No NCF_TS")); 325 326 if (tsp == NULL && ticksp == NULL) 327 return; 328 329 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); 330 if (tsp != NULL) 331 *tsp = ncp_ts->nc_time; 332 if (ticksp != NULL) 333 *ticksp = ncp_ts->nc_ticks; 334 } 335 336 static int __read_mostly doingcache = 1; /* 1 => enable the cache */ 337 SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0, 338 "VFS namecache enabled"); 339 340 /* Export size information to userland */ 341 SYSCTL_INT(_debug_sizeof, OID_AUTO, namecache, CTLFLAG_RD, SYSCTL_NULL_INT_PTR, 342 sizeof(struct namecache), "sizeof(struct namecache)"); 343 344 /* 345 * The new name cache statistics 346 */ 347 static SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, 348 "Name cache statistics"); 349 #define STATNODE_ULONG(name, descr) \ 350 SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, descr); 351 #define STATNODE_COUNTER(name, descr) \ 352 static counter_u64_t __read_mostly name; \ 353 SYSCTL_COUNTER_U64(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, descr); 354 STATNODE_ULONG(numneg, "Number of negative cache entries"); 355 STATNODE_ULONG(numcache, "Number of cache entries"); 356 STATNODE_COUNTER(numcalls, "Number of cache lookups"); 357 STATNODE_COUNTER(dothits, "Number of '.' hits"); 358 STATNODE_COUNTER(dotdothits, "Number of '..' hits"); 359 STATNODE_COUNTER(numchecks, "Number of checks in lookup"); 360 STATNODE_COUNTER(nummiss, "Number of cache misses"); 361 STATNODE_COUNTER(nummisszap, "Number of cache misses we do not want to cache"); 362 STATNODE_COUNTER(numposzaps, 363 "Number of cache hits (positive) we do not want to cache"); 364 STATNODE_COUNTER(numposhits, "Number of cache hits (positive)"); 365 STATNODE_COUNTER(numnegzaps, 366 "Number of cache hits (negative) we do not want to cache"); 367 STATNODE_COUNTER(numneghits, "Number of cache hits (negative)"); 368 /* These count for kern___getcwd(), too. */ 369 STATNODE_COUNTER(numfullpathcalls, "Number of fullpath search calls"); 370 STATNODE_COUNTER(numfullpathfail1, "Number of fullpath search errors (ENOTDIR)"); 371 STATNODE_COUNTER(numfullpathfail2, 372 "Number of fullpath search errors (VOP_VPTOCNP failures)"); 373 STATNODE_COUNTER(numfullpathfail4, "Number of fullpath search errors (ENOMEM)"); 374 STATNODE_COUNTER(numfullpathfound, "Number of successful fullpath calls"); 375 static long zap_and_exit_bucket_fail; STATNODE_ULONG(zap_and_exit_bucket_fail, 376 "Number of times zap_and_exit failed to lock"); 377 static long cache_lock_vnodes_cel_3_failures; 378 STATNODE_ULONG(cache_lock_vnodes_cel_3_failures, 379 "Number of times 3-way vnode locking failed"); 380 381 static void cache_zap_locked(struct namecache *ncp, bool neg_locked); 382 static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 383 char *buf, char **retbuf, u_int buflen); 384 385 static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); 386 387 static int cache_yield; 388 SYSCTL_INT(_vfs_cache, OID_AUTO, yield, CTLFLAG_RD, &cache_yield, 0, 389 "Number of times cache called yield"); 390 391 static void 392 cache_maybe_yield(void) 393 { 394 395 if (should_yield()) { 396 cache_yield++; 397 kern_yield(PRI_USER); 398 } 399 } 400 401 static inline void 402 cache_assert_vlp_locked(struct mtx *vlp) 403 { 404 405 if (vlp != NULL) 406 mtx_assert(vlp, MA_OWNED); 407 } 408 409 static inline void 410 cache_assert_vnode_locked(struct vnode *vp) 411 { 412 struct mtx *vlp; 413 414 vlp = VP2VNODELOCK(vp); 415 cache_assert_vlp_locked(vlp); 416 } 417 418 static uint32_t 419 cache_get_hash(char *name, u_char len, struct vnode *dvp) 420 { 421 uint32_t hash; 422 423 hash = fnv_32_buf(name, len, FNV1_32_INIT); 424 hash = fnv_32_buf(&dvp, sizeof(dvp), hash); 425 return (hash); 426 } 427 428 static inline struct rwlock * 429 NCP2BUCKETLOCK(struct namecache *ncp) 430 { 431 uint32_t hash; 432 433 hash = cache_get_hash(ncp->nc_name, ncp->nc_nlen, ncp->nc_dvp); 434 return (HASH2BUCKETLOCK(hash)); 435 } 436 437 #ifdef INVARIANTS 438 static void 439 cache_assert_bucket_locked(struct namecache *ncp, int mode) 440 { 441 struct rwlock *blp; 442 443 blp = NCP2BUCKETLOCK(ncp); 444 rw_assert(blp, mode); 445 } 446 #else 447 #define cache_assert_bucket_locked(x, y) do { } while (0) 448 #endif 449 450 #define cache_sort(x, y) _cache_sort((void **)(x), (void **)(y)) 451 static void 452 _cache_sort(void **p1, void **p2) 453 { 454 void *tmp; 455 456 if (*p1 > *p2) { 457 tmp = *p2; 458 *p2 = *p1; 459 *p1 = tmp; 460 } 461 } 462 463 static void 464 cache_lock_all_buckets(void) 465 { 466 u_int i; 467 468 for (i = 0; i < numbucketlocks; i++) 469 rw_wlock(&bucketlocks[i]); 470 } 471 472 static void 473 cache_unlock_all_buckets(void) 474 { 475 u_int i; 476 477 for (i = 0; i < numbucketlocks; i++) 478 rw_wunlock(&bucketlocks[i]); 479 } 480 481 static void 482 cache_lock_all_vnodes(void) 483 { 484 u_int i; 485 486 for (i = 0; i < numvnodelocks; i++) 487 mtx_lock(&vnodelocks[i]); 488 } 489 490 static void 491 cache_unlock_all_vnodes(void) 492 { 493 u_int i; 494 495 for (i = 0; i < numvnodelocks; i++) 496 mtx_unlock(&vnodelocks[i]); 497 } 498 499 static int 500 cache_trylock_vnodes(struct mtx *vlp1, struct mtx *vlp2) 501 { 502 503 cache_sort(&vlp1, &vlp2); 504 MPASS(vlp2 != NULL); 505 506 if (vlp1 != NULL) { 507 if (!mtx_trylock(vlp1)) 508 return (EAGAIN); 509 } 510 if (!mtx_trylock(vlp2)) { 511 if (vlp1 != NULL) 512 mtx_unlock(vlp1); 513 return (EAGAIN); 514 } 515 516 return (0); 517 } 518 519 static void 520 cache_unlock_vnodes(struct mtx *vlp1, struct mtx *vlp2) 521 { 522 523 MPASS(vlp1 != NULL || vlp2 != NULL); 524 525 if (vlp1 != NULL) 526 mtx_unlock(vlp1); 527 if (vlp2 != NULL) 528 mtx_unlock(vlp2); 529 } 530 531 static int 532 sysctl_nchstats(SYSCTL_HANDLER_ARGS) 533 { 534 struct nchstats snap; 535 536 if (req->oldptr == NULL) 537 return (SYSCTL_OUT(req, 0, sizeof(snap))); 538 539 snap = nchstats; 540 snap.ncs_goodhits = counter_u64_fetch(numposhits); 541 snap.ncs_neghits = counter_u64_fetch(numneghits); 542 snap.ncs_badhits = counter_u64_fetch(numposzaps) + 543 counter_u64_fetch(numnegzaps); 544 snap.ncs_miss = counter_u64_fetch(nummisszap) + 545 counter_u64_fetch(nummiss); 546 547 return (SYSCTL_OUT(req, &snap, sizeof(snap))); 548 } 549 SYSCTL_PROC(_vfs_cache, OID_AUTO, nchstats, CTLTYPE_OPAQUE | CTLFLAG_RD | 550 CTLFLAG_MPSAFE, 0, 0, sysctl_nchstats, "LU", 551 "VFS cache effectiveness statistics"); 552 553 #ifdef DIAGNOSTIC 554 /* 555 * Grab an atomic snapshot of the name cache hash chain lengths 556 */ 557 static SYSCTL_NODE(_debug, OID_AUTO, hashstat, CTLFLAG_RW, NULL, 558 "hash table stats"); 559 560 static int 561 sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS) 562 { 563 struct nchashhead *ncpp; 564 struct namecache *ncp; 565 int i, error, n_nchash, *cntbuf; 566 567 retry: 568 n_nchash = nchash + 1; /* nchash is max index, not count */ 569 if (req->oldptr == NULL) 570 return SYSCTL_OUT(req, 0, n_nchash * sizeof(int)); 571 cntbuf = malloc(n_nchash * sizeof(int), M_TEMP, M_ZERO | M_WAITOK); 572 cache_lock_all_buckets(); 573 if (n_nchash != nchash + 1) { 574 cache_unlock_all_buckets(); 575 free(cntbuf, M_TEMP); 576 goto retry; 577 } 578 /* Scan hash tables counting entries */ 579 for (ncpp = nchashtbl, i = 0; i < n_nchash; ncpp++, i++) 580 LIST_FOREACH(ncp, ncpp, nc_hash) 581 cntbuf[i]++; 582 cache_unlock_all_buckets(); 583 for (error = 0, i = 0; i < n_nchash; i++) 584 if ((error = SYSCTL_OUT(req, &cntbuf[i], sizeof(int))) != 0) 585 break; 586 free(cntbuf, M_TEMP); 587 return (error); 588 } 589 SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD| 590 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_rawnchash, "S,int", 591 "nchash chain lengths"); 592 593 static int 594 sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS) 595 { 596 int error; 597 struct nchashhead *ncpp; 598 struct namecache *ncp; 599 int n_nchash; 600 int count, maxlength, used, pct; 601 602 if (!req->oldptr) 603 return SYSCTL_OUT(req, 0, 4 * sizeof(int)); 604 605 cache_lock_all_buckets(); 606 n_nchash = nchash + 1; /* nchash is max index, not count */ 607 used = 0; 608 maxlength = 0; 609 610 /* Scan hash tables for applicable entries */ 611 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { 612 count = 0; 613 LIST_FOREACH(ncp, ncpp, nc_hash) { 614 count++; 615 } 616 if (count) 617 used++; 618 if (maxlength < count) 619 maxlength = count; 620 } 621 n_nchash = nchash + 1; 622 cache_unlock_all_buckets(); 623 pct = (used * 100) / (n_nchash / 100); 624 error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash)); 625 if (error) 626 return (error); 627 error = SYSCTL_OUT(req, &used, sizeof(used)); 628 if (error) 629 return (error); 630 error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength)); 631 if (error) 632 return (error); 633 error = SYSCTL_OUT(req, &pct, sizeof(pct)); 634 if (error) 635 return (error); 636 return (0); 637 } 638 SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD| 639 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_nchash, "I", 640 "nchash statistics (number of total/used buckets, maximum chain length, usage percentage)"); 641 #endif 642 643 /* 644 * Negative entries management 645 * 646 * A variation of LRU scheme is used. New entries are hashed into one of 647 * numneglists cold lists. Entries get promoted to the hot list on first hit. 648 * Partial LRU for the hot list is maintained by requeueing them every 649 * ncneghitsrequeue hits. 650 * 651 * The shrinker will demote hot list head and evict from the cold list in a 652 * round-robin manner. 653 */ 654 static void 655 cache_negative_hit(struct namecache *ncp) 656 { 657 struct neglist *neglist; 658 u_int hits; 659 660 MPASS(ncp->nc_flag & NCF_NEGATIVE); 661 hits = atomic_fetchadd_int(&ncp->nc_neghits, 1); 662 if (ncp->nc_flag & NCF_HOTNEGATIVE) { 663 if ((hits % ncneghitsrequeue) != 0) 664 return; 665 mtx_lock(&ncneg_hot.nl_lock); 666 if (ncp->nc_flag & NCF_HOTNEGATIVE) { 667 TAILQ_REMOVE(&ncneg_hot.nl_list, ncp, nc_dst); 668 TAILQ_INSERT_TAIL(&ncneg_hot.nl_list, ncp, nc_dst); 669 mtx_unlock(&ncneg_hot.nl_lock); 670 return; 671 } 672 /* 673 * The shrinker cleared the flag and removed the entry from 674 * the hot list. Put it back. 675 */ 676 } else { 677 mtx_lock(&ncneg_hot.nl_lock); 678 } 679 neglist = NCP2NEGLIST(ncp); 680 mtx_lock(&neglist->nl_lock); 681 if (!(ncp->nc_flag & NCF_HOTNEGATIVE)) { 682 TAILQ_REMOVE(&neglist->nl_list, ncp, nc_dst); 683 TAILQ_INSERT_TAIL(&ncneg_hot.nl_list, ncp, nc_dst); 684 ncp->nc_flag |= NCF_HOTNEGATIVE; 685 } 686 mtx_unlock(&neglist->nl_lock); 687 mtx_unlock(&ncneg_hot.nl_lock); 688 } 689 690 static void 691 cache_negative_insert(struct namecache *ncp, bool neg_locked) 692 { 693 struct neglist *neglist; 694 695 MPASS(ncp->nc_flag & NCF_NEGATIVE); 696 cache_assert_bucket_locked(ncp, RA_WLOCKED); 697 neglist = NCP2NEGLIST(ncp); 698 if (!neg_locked) { 699 mtx_lock(&neglist->nl_lock); 700 } else { 701 mtx_assert(&neglist->nl_lock, MA_OWNED); 702 } 703 TAILQ_INSERT_TAIL(&neglist->nl_list, ncp, nc_dst); 704 if (!neg_locked) 705 mtx_unlock(&neglist->nl_lock); 706 atomic_add_rel_long(&numneg, 1); 707 } 708 709 static void 710 cache_negative_remove(struct namecache *ncp, bool neg_locked) 711 { 712 struct neglist *neglist; 713 bool hot_locked = false; 714 bool list_locked = false; 715 716 MPASS(ncp->nc_flag & NCF_NEGATIVE); 717 cache_assert_bucket_locked(ncp, RA_WLOCKED); 718 neglist = NCP2NEGLIST(ncp); 719 if (!neg_locked) { 720 if (ncp->nc_flag & NCF_HOTNEGATIVE) { 721 hot_locked = true; 722 mtx_lock(&ncneg_hot.nl_lock); 723 if (!(ncp->nc_flag & NCF_HOTNEGATIVE)) { 724 list_locked = true; 725 mtx_lock(&neglist->nl_lock); 726 } 727 } else { 728 list_locked = true; 729 mtx_lock(&neglist->nl_lock); 730 } 731 } 732 if (ncp->nc_flag & NCF_HOTNEGATIVE) { 733 mtx_assert(&ncneg_hot.nl_lock, MA_OWNED); 734 TAILQ_REMOVE(&ncneg_hot.nl_list, ncp, nc_dst); 735 } else { 736 mtx_assert(&neglist->nl_lock, MA_OWNED); 737 TAILQ_REMOVE(&neglist->nl_list, ncp, nc_dst); 738 } 739 if (list_locked) 740 mtx_unlock(&neglist->nl_lock); 741 if (hot_locked) 742 mtx_unlock(&ncneg_hot.nl_lock); 743 atomic_subtract_rel_long(&numneg, 1); 744 } 745 746 static void 747 cache_negative_shrink_select(int start, struct namecache **ncpp, 748 struct neglist **neglistpp) 749 { 750 struct neglist *neglist; 751 struct namecache *ncp; 752 int i; 753 754 *ncpp = ncp = NULL; 755 neglist = NULL; 756 757 for (i = start; i < numneglists; i++) { 758 neglist = &neglists[i]; 759 if (TAILQ_FIRST(&neglist->nl_list) == NULL) 760 continue; 761 mtx_lock(&neglist->nl_lock); 762 ncp = TAILQ_FIRST(&neglist->nl_list); 763 if (ncp != NULL) 764 break; 765 mtx_unlock(&neglist->nl_lock); 766 } 767 768 *neglistpp = neglist; 769 *ncpp = ncp; 770 } 771 772 static void 773 cache_negative_zap_one(void) 774 { 775 struct namecache *ncp, *ncp2; 776 struct neglist *neglist; 777 struct mtx *dvlp; 778 struct rwlock *blp; 779 780 if (!mtx_trylock(&ncneg_shrink_lock)) 781 return; 782 783 mtx_lock(&ncneg_hot.nl_lock); 784 ncp = TAILQ_FIRST(&ncneg_hot.nl_list); 785 if (ncp != NULL) { 786 neglist = NCP2NEGLIST(ncp); 787 mtx_lock(&neglist->nl_lock); 788 TAILQ_REMOVE(&ncneg_hot.nl_list, ncp, nc_dst); 789 TAILQ_INSERT_TAIL(&neglist->nl_list, ncp, nc_dst); 790 ncp->nc_flag &= ~NCF_HOTNEGATIVE; 791 mtx_unlock(&neglist->nl_lock); 792 } 793 794 cache_negative_shrink_select(shrink_list_turn, &ncp, &neglist); 795 shrink_list_turn++; 796 if (shrink_list_turn == numneglists) 797 shrink_list_turn = 0; 798 if (ncp == NULL && shrink_list_turn == 0) 799 cache_negative_shrink_select(shrink_list_turn, &ncp, &neglist); 800 if (ncp == NULL) { 801 mtx_unlock(&ncneg_hot.nl_lock); 802 goto out; 803 } 804 805 MPASS(ncp->nc_flag & NCF_NEGATIVE); 806 dvlp = VP2VNODELOCK(ncp->nc_dvp); 807 blp = NCP2BUCKETLOCK(ncp); 808 mtx_unlock(&neglist->nl_lock); 809 mtx_unlock(&ncneg_hot.nl_lock); 810 mtx_lock(dvlp); 811 rw_wlock(blp); 812 mtx_lock(&neglist->nl_lock); 813 ncp2 = TAILQ_FIRST(&neglist->nl_list); 814 if (ncp != ncp2 || dvlp != VP2VNODELOCK(ncp2->nc_dvp) || 815 blp != NCP2BUCKETLOCK(ncp2) || !(ncp2->nc_flag & NCF_NEGATIVE)) { 816 ncp = NULL; 817 goto out_unlock_all; 818 } 819 SDT_PROBE3(vfs, namecache, shrink_negative, done, ncp->nc_dvp, 820 ncp->nc_name, ncp->nc_neghits); 821 822 cache_zap_locked(ncp, true); 823 out_unlock_all: 824 mtx_unlock(&neglist->nl_lock); 825 rw_wunlock(blp); 826 mtx_unlock(dvlp); 827 out: 828 mtx_unlock(&ncneg_shrink_lock); 829 cache_free(ncp); 830 } 831 832 /* 833 * cache_zap_locked(): 834 * 835 * Removes a namecache entry from cache, whether it contains an actual 836 * pointer to a vnode or if it is just a negative cache entry. 837 */ 838 static void 839 cache_zap_locked(struct namecache *ncp, bool neg_locked) 840 { 841 842 if (!(ncp->nc_flag & NCF_NEGATIVE)) 843 cache_assert_vnode_locked(ncp->nc_vp); 844 cache_assert_vnode_locked(ncp->nc_dvp); 845 cache_assert_bucket_locked(ncp, RA_WLOCKED); 846 847 CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp, 848 (ncp->nc_flag & NCF_NEGATIVE) ? NULL : ncp->nc_vp); 849 if (!(ncp->nc_flag & NCF_NEGATIVE)) { 850 SDT_PROBE3(vfs, namecache, zap, done, ncp->nc_dvp, 851 ncp->nc_name, ncp->nc_vp); 852 } else { 853 SDT_PROBE3(vfs, namecache, zap_negative, done, ncp->nc_dvp, 854 ncp->nc_name, ncp->nc_neghits); 855 } 856 LIST_REMOVE(ncp, nc_hash); 857 if (!(ncp->nc_flag & NCF_NEGATIVE)) { 858 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst); 859 if (ncp == ncp->nc_vp->v_cache_dd) 860 ncp->nc_vp->v_cache_dd = NULL; 861 } else { 862 cache_negative_remove(ncp, neg_locked); 863 } 864 if (ncp->nc_flag & NCF_ISDOTDOT) { 865 if (ncp == ncp->nc_dvp->v_cache_dd) 866 ncp->nc_dvp->v_cache_dd = NULL; 867 } else { 868 LIST_REMOVE(ncp, nc_src); 869 if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) { 870 ncp->nc_flag |= NCF_DVDROP; 871 atomic_subtract_rel_long(&numcachehv, 1); 872 } 873 } 874 atomic_subtract_rel_long(&numcache, 1); 875 } 876 877 static void 878 cache_zap_negative_locked_vnode_kl(struct namecache *ncp, struct vnode *vp) 879 { 880 struct rwlock *blp; 881 882 MPASS(ncp->nc_dvp == vp); 883 MPASS(ncp->nc_flag & NCF_NEGATIVE); 884 cache_assert_vnode_locked(vp); 885 886 blp = NCP2BUCKETLOCK(ncp); 887 rw_wlock(blp); 888 cache_zap_locked(ncp, false); 889 rw_wunlock(blp); 890 } 891 892 static bool 893 cache_zap_locked_vnode_kl2(struct namecache *ncp, struct vnode *vp, 894 struct mtx **vlpp) 895 { 896 struct mtx *pvlp, *vlp1, *vlp2, *to_unlock; 897 struct rwlock *blp; 898 899 MPASS(vp == ncp->nc_dvp || vp == ncp->nc_vp); 900 cache_assert_vnode_locked(vp); 901 902 if (ncp->nc_flag & NCF_NEGATIVE) { 903 if (*vlpp != NULL) { 904 mtx_unlock(*vlpp); 905 *vlpp = NULL; 906 } 907 cache_zap_negative_locked_vnode_kl(ncp, vp); 908 return (true); 909 } 910 911 pvlp = VP2VNODELOCK(vp); 912 blp = NCP2BUCKETLOCK(ncp); 913 vlp1 = VP2VNODELOCK(ncp->nc_dvp); 914 vlp2 = VP2VNODELOCK(ncp->nc_vp); 915 916 if (*vlpp == vlp1 || *vlpp == vlp2) { 917 to_unlock = *vlpp; 918 *vlpp = NULL; 919 } else { 920 if (*vlpp != NULL) { 921 mtx_unlock(*vlpp); 922 *vlpp = NULL; 923 } 924 cache_sort(&vlp1, &vlp2); 925 if (vlp1 == pvlp) { 926 mtx_lock(vlp2); 927 to_unlock = vlp2; 928 } else { 929 if (!mtx_trylock(vlp1)) 930 goto out_relock; 931 to_unlock = vlp1; 932 } 933 } 934 rw_wlock(blp); 935 cache_zap_locked(ncp, false); 936 rw_wunlock(blp); 937 if (to_unlock != NULL) 938 mtx_unlock(to_unlock); 939 return (true); 940 941 out_relock: 942 mtx_unlock(vlp2); 943 mtx_lock(vlp1); 944 mtx_lock(vlp2); 945 MPASS(*vlpp == NULL); 946 *vlpp = vlp1; 947 return (false); 948 } 949 950 static int 951 cache_zap_locked_vnode(struct namecache *ncp, struct vnode *vp) 952 { 953 struct mtx *pvlp, *vlp1, *vlp2, *to_unlock; 954 struct rwlock *blp; 955 int error = 0; 956 957 MPASS(vp == ncp->nc_dvp || vp == ncp->nc_vp); 958 cache_assert_vnode_locked(vp); 959 960 pvlp = VP2VNODELOCK(vp); 961 if (ncp->nc_flag & NCF_NEGATIVE) { 962 cache_zap_negative_locked_vnode_kl(ncp, vp); 963 goto out; 964 } 965 966 blp = NCP2BUCKETLOCK(ncp); 967 vlp1 = VP2VNODELOCK(ncp->nc_dvp); 968 vlp2 = VP2VNODELOCK(ncp->nc_vp); 969 cache_sort(&vlp1, &vlp2); 970 if (vlp1 == pvlp) { 971 mtx_lock(vlp2); 972 to_unlock = vlp2; 973 } else { 974 if (!mtx_trylock(vlp1)) { 975 error = EAGAIN; 976 goto out; 977 } 978 to_unlock = vlp1; 979 } 980 rw_wlock(blp); 981 cache_zap_locked(ncp, false); 982 rw_wunlock(blp); 983 mtx_unlock(to_unlock); 984 out: 985 mtx_unlock(pvlp); 986 return (error); 987 } 988 989 static int 990 cache_zap_wlocked_bucket(struct namecache *ncp, struct rwlock *blp) 991 { 992 struct mtx *dvlp, *vlp; 993 994 cache_assert_bucket_locked(ncp, RA_WLOCKED); 995 996 dvlp = VP2VNODELOCK(ncp->nc_dvp); 997 vlp = NULL; 998 if (!(ncp->nc_flag & NCF_NEGATIVE)) 999 vlp = VP2VNODELOCK(ncp->nc_vp); 1000 if (cache_trylock_vnodes(dvlp, vlp) == 0) { 1001 cache_zap_locked(ncp, false); 1002 rw_wunlock(blp); 1003 cache_unlock_vnodes(dvlp, vlp); 1004 return (0); 1005 } 1006 1007 rw_wunlock(blp); 1008 return (EAGAIN); 1009 } 1010 1011 static int 1012 cache_zap_rlocked_bucket(struct namecache *ncp, struct rwlock *blp) 1013 { 1014 struct mtx *dvlp, *vlp; 1015 1016 cache_assert_bucket_locked(ncp, RA_RLOCKED); 1017 1018 dvlp = VP2VNODELOCK(ncp->nc_dvp); 1019 vlp = NULL; 1020 if (!(ncp->nc_flag & NCF_NEGATIVE)) 1021 vlp = VP2VNODELOCK(ncp->nc_vp); 1022 if (cache_trylock_vnodes(dvlp, vlp) == 0) { 1023 rw_runlock(blp); 1024 rw_wlock(blp); 1025 cache_zap_locked(ncp, false); 1026 rw_wunlock(blp); 1027 cache_unlock_vnodes(dvlp, vlp); 1028 return (0); 1029 } 1030 1031 rw_runlock(blp); 1032 return (EAGAIN); 1033 } 1034 1035 static int 1036 cache_zap_wlocked_bucket_kl(struct namecache *ncp, struct rwlock *blp, 1037 struct mtx **vlpp1, struct mtx **vlpp2) 1038 { 1039 struct mtx *dvlp, *vlp; 1040 1041 cache_assert_bucket_locked(ncp, RA_WLOCKED); 1042 1043 dvlp = VP2VNODELOCK(ncp->nc_dvp); 1044 vlp = NULL; 1045 if (!(ncp->nc_flag & NCF_NEGATIVE)) 1046 vlp = VP2VNODELOCK(ncp->nc_vp); 1047 cache_sort(&dvlp, &vlp); 1048 1049 if (*vlpp1 == dvlp && *vlpp2 == vlp) { 1050 cache_zap_locked(ncp, false); 1051 cache_unlock_vnodes(dvlp, vlp); 1052 *vlpp1 = NULL; 1053 *vlpp2 = NULL; 1054 return (0); 1055 } 1056 1057 if (*vlpp1 != NULL) 1058 mtx_unlock(*vlpp1); 1059 if (*vlpp2 != NULL) 1060 mtx_unlock(*vlpp2); 1061 *vlpp1 = NULL; 1062 *vlpp2 = NULL; 1063 1064 if (cache_trylock_vnodes(dvlp, vlp) == 0) { 1065 cache_zap_locked(ncp, false); 1066 cache_unlock_vnodes(dvlp, vlp); 1067 return (0); 1068 } 1069 1070 rw_wunlock(blp); 1071 *vlpp1 = dvlp; 1072 *vlpp2 = vlp; 1073 if (*vlpp1 != NULL) 1074 mtx_lock(*vlpp1); 1075 mtx_lock(*vlpp2); 1076 rw_wlock(blp); 1077 return (EAGAIN); 1078 } 1079 1080 static void 1081 cache_lookup_unlock(struct rwlock *blp, struct mtx *vlp) 1082 { 1083 1084 if (blp != NULL) { 1085 rw_runlock(blp); 1086 } else { 1087 mtx_unlock(vlp); 1088 } 1089 } 1090 1091 static int __noinline 1092 cache_lookup_dot(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, 1093 struct timespec *tsp, int *ticksp) 1094 { 1095 int ltype; 1096 1097 *vpp = dvp; 1098 CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .", 1099 dvp, cnp->cn_nameptr); 1100 counter_u64_add(dothits, 1); 1101 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ".", *vpp); 1102 if (tsp != NULL) 1103 timespecclear(tsp); 1104 if (ticksp != NULL) 1105 *ticksp = ticks; 1106 vrefact(*vpp); 1107 /* 1108 * When we lookup "." we still can be asked to lock it 1109 * differently... 1110 */ 1111 ltype = cnp->cn_lkflags & LK_TYPE_MASK; 1112 if (ltype != VOP_ISLOCKED(*vpp)) { 1113 if (ltype == LK_EXCLUSIVE) { 1114 vn_lock(*vpp, LK_UPGRADE | LK_RETRY); 1115 if ((*vpp)->v_iflag & VI_DOOMED) { 1116 /* forced unmount */ 1117 vrele(*vpp); 1118 *vpp = NULL; 1119 return (ENOENT); 1120 } 1121 } else 1122 vn_lock(*vpp, LK_DOWNGRADE | LK_RETRY); 1123 } 1124 return (-1); 1125 } 1126 1127 /* 1128 * Lookup an entry in the cache 1129 * 1130 * Lookup is called with dvp pointing to the directory to search, 1131 * cnp pointing to the name of the entry being sought. If the lookup 1132 * succeeds, the vnode is returned in *vpp, and a status of -1 is 1133 * returned. If the lookup determines that the name does not exist 1134 * (negative caching), a status of ENOENT is returned. If the lookup 1135 * fails, a status of zero is returned. If the directory vnode is 1136 * recycled out from under us due to a forced unmount, a status of 1137 * ENOENT is returned. 1138 * 1139 * vpp is locked and ref'd on return. If we're looking up DOTDOT, dvp is 1140 * unlocked. If we're looking up . an extra ref is taken, but the lock is 1141 * not recursively acquired. 1142 */ 1143 1144 static __noinline int 1145 cache_lookup_nomakeentry(struct vnode *dvp, struct vnode **vpp, 1146 struct componentname *cnp, struct timespec *tsp, int *ticksp) 1147 { 1148 struct namecache *ncp; 1149 struct rwlock *blp; 1150 struct mtx *dvlp, *dvlp2; 1151 uint32_t hash; 1152 int error; 1153 1154 if (cnp->cn_namelen == 2 && 1155 cnp->cn_nameptr[0] == '.' && cnp->cn_nameptr[1] == '.') { 1156 counter_u64_add(dotdothits, 1); 1157 dvlp = VP2VNODELOCK(dvp); 1158 dvlp2 = NULL; 1159 mtx_lock(dvlp); 1160 retry_dotdot: 1161 ncp = dvp->v_cache_dd; 1162 if (ncp == NULL) { 1163 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, 1164 "..", NULL); 1165 mtx_unlock(dvlp); 1166 if (dvlp2 != NULL) 1167 mtx_unlock(dvlp2); 1168 return (0); 1169 } 1170 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) { 1171 if (ncp->nc_dvp != dvp) 1172 panic("dvp %p v_cache_dd %p\n", dvp, ncp); 1173 if (!cache_zap_locked_vnode_kl2(ncp, 1174 dvp, &dvlp2)) 1175 goto retry_dotdot; 1176 MPASS(dvp->v_cache_dd == NULL); 1177 mtx_unlock(dvlp); 1178 if (dvlp2 != NULL) 1179 mtx_unlock(dvlp2); 1180 cache_free(ncp); 1181 } else { 1182 dvp->v_cache_dd = NULL; 1183 mtx_unlock(dvlp); 1184 if (dvlp2 != NULL) 1185 mtx_unlock(dvlp2); 1186 } 1187 return (0); 1188 } 1189 1190 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp); 1191 blp = HASH2BUCKETLOCK(hash); 1192 retry: 1193 if (LIST_EMPTY(NCHHASH(hash))) 1194 goto out_no_entry; 1195 1196 rw_wlock(blp); 1197 1198 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 1199 counter_u64_add(numchecks, 1); 1200 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 1201 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 1202 break; 1203 } 1204 1205 /* We failed to find an entry */ 1206 if (ncp == NULL) { 1207 rw_wunlock(blp); 1208 goto out_no_entry; 1209 } 1210 1211 counter_u64_add(numposzaps, 1); 1212 1213 error = cache_zap_wlocked_bucket(ncp, blp); 1214 if (error != 0) { 1215 zap_and_exit_bucket_fail++; 1216 cache_maybe_yield(); 1217 goto retry; 1218 } 1219 cache_free(ncp); 1220 return (0); 1221 out_no_entry: 1222 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr, NULL); 1223 counter_u64_add(nummisszap, 1); 1224 return (0); 1225 } 1226 1227 int 1228 cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, 1229 struct timespec *tsp, int *ticksp) 1230 { 1231 struct namecache_ts *ncp_ts; 1232 struct namecache *ncp; 1233 struct rwlock *blp; 1234 struct mtx *dvlp; 1235 uint32_t hash; 1236 int error, ltype; 1237 1238 if (__predict_false(!doingcache)) { 1239 cnp->cn_flags &= ~MAKEENTRY; 1240 return (0); 1241 } 1242 1243 counter_u64_add(numcalls, 1); 1244 1245 if (__predict_false(cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.')) 1246 return (cache_lookup_dot(dvp, vpp, cnp, tsp, ticksp)); 1247 1248 if ((cnp->cn_flags & MAKEENTRY) == 0) 1249 return (cache_lookup_nomakeentry(dvp, vpp, cnp, tsp, ticksp)); 1250 1251 retry: 1252 blp = NULL; 1253 dvlp = NULL; 1254 error = 0; 1255 if (cnp->cn_namelen == 2 && 1256 cnp->cn_nameptr[0] == '.' && cnp->cn_nameptr[1] == '.') { 1257 counter_u64_add(dotdothits, 1); 1258 dvlp = VP2VNODELOCK(dvp); 1259 mtx_lock(dvlp); 1260 ncp = dvp->v_cache_dd; 1261 if (ncp == NULL) { 1262 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, 1263 "..", NULL); 1264 mtx_unlock(dvlp); 1265 return (0); 1266 } 1267 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) { 1268 if (ncp->nc_flag & NCF_NEGATIVE) 1269 *vpp = NULL; 1270 else 1271 *vpp = ncp->nc_vp; 1272 } else 1273 *vpp = ncp->nc_dvp; 1274 /* Return failure if negative entry was found. */ 1275 if (*vpp == NULL) 1276 goto negative_success; 1277 CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..", 1278 dvp, cnp->cn_nameptr, *vpp); 1279 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, "..", 1280 *vpp); 1281 cache_out_ts(ncp, tsp, ticksp); 1282 if ((ncp->nc_flag & (NCF_ISDOTDOT | NCF_DTS)) == 1283 NCF_DTS && tsp != NULL) { 1284 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); 1285 *tsp = ncp_ts->nc_dotdottime; 1286 } 1287 goto success; 1288 } 1289 1290 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp); 1291 blp = HASH2BUCKETLOCK(hash); 1292 rw_rlock(blp); 1293 1294 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 1295 counter_u64_add(numchecks, 1); 1296 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 1297 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 1298 break; 1299 } 1300 1301 /* We failed to find an entry */ 1302 if (ncp == NULL) { 1303 rw_runlock(blp); 1304 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr, 1305 NULL); 1306 counter_u64_add(nummiss, 1); 1307 return (0); 1308 } 1309 1310 /* We found a "positive" match, return the vnode */ 1311 if (!(ncp->nc_flag & NCF_NEGATIVE)) { 1312 counter_u64_add(numposhits, 1); 1313 *vpp = ncp->nc_vp; 1314 CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p", 1315 dvp, cnp->cn_nameptr, *vpp, ncp); 1316 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ncp->nc_name, 1317 *vpp); 1318 cache_out_ts(ncp, tsp, ticksp); 1319 goto success; 1320 } 1321 1322 negative_success: 1323 /* We found a negative match, and want to create it, so purge */ 1324 if (cnp->cn_nameiop == CREATE) { 1325 counter_u64_add(numnegzaps, 1); 1326 goto zap_and_exit; 1327 } 1328 1329 counter_u64_add(numneghits, 1); 1330 cache_negative_hit(ncp); 1331 if (ncp->nc_flag & NCF_WHITE) 1332 cnp->cn_flags |= ISWHITEOUT; 1333 SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp, 1334 ncp->nc_name); 1335 cache_out_ts(ncp, tsp, ticksp); 1336 cache_lookup_unlock(blp, dvlp); 1337 return (ENOENT); 1338 1339 success: 1340 /* 1341 * On success we return a locked and ref'd vnode as per the lookup 1342 * protocol. 1343 */ 1344 MPASS(dvp != *vpp); 1345 ltype = 0; /* silence gcc warning */ 1346 if (cnp->cn_flags & ISDOTDOT) { 1347 ltype = VOP_ISLOCKED(dvp); 1348 VOP_UNLOCK(dvp, 0); 1349 } 1350 vhold(*vpp); 1351 cache_lookup_unlock(blp, dvlp); 1352 error = vget(*vpp, cnp->cn_lkflags | LK_VNHELD, cnp->cn_thread); 1353 if (cnp->cn_flags & ISDOTDOT) { 1354 vn_lock(dvp, ltype | LK_RETRY); 1355 if (dvp->v_iflag & VI_DOOMED) { 1356 if (error == 0) 1357 vput(*vpp); 1358 *vpp = NULL; 1359 return (ENOENT); 1360 } 1361 } 1362 if (error) { 1363 *vpp = NULL; 1364 goto retry; 1365 } 1366 if ((cnp->cn_flags & ISLASTCN) && 1367 (cnp->cn_lkflags & LK_TYPE_MASK) == LK_EXCLUSIVE) { 1368 ASSERT_VOP_ELOCKED(*vpp, "cache_lookup"); 1369 } 1370 return (-1); 1371 1372 zap_and_exit: 1373 if (blp != NULL) 1374 error = cache_zap_rlocked_bucket(ncp, blp); 1375 else 1376 error = cache_zap_locked_vnode(ncp, dvp); 1377 if (error != 0) { 1378 zap_and_exit_bucket_fail++; 1379 cache_maybe_yield(); 1380 goto retry; 1381 } 1382 cache_free(ncp); 1383 return (0); 1384 } 1385 1386 struct celockstate { 1387 struct mtx *vlp[3]; 1388 struct rwlock *blp[2]; 1389 }; 1390 CTASSERT((nitems(((struct celockstate *)0)->vlp) == 3)); 1391 CTASSERT((nitems(((struct celockstate *)0)->blp) == 2)); 1392 1393 static inline void 1394 cache_celockstate_init(struct celockstate *cel) 1395 { 1396 1397 bzero(cel, sizeof(*cel)); 1398 } 1399 1400 static void 1401 cache_lock_vnodes_cel(struct celockstate *cel, struct vnode *vp, 1402 struct vnode *dvp) 1403 { 1404 struct mtx *vlp1, *vlp2; 1405 1406 MPASS(cel->vlp[0] == NULL); 1407 MPASS(cel->vlp[1] == NULL); 1408 MPASS(cel->vlp[2] == NULL); 1409 1410 MPASS(vp != NULL || dvp != NULL); 1411 1412 vlp1 = VP2VNODELOCK(vp); 1413 vlp2 = VP2VNODELOCK(dvp); 1414 cache_sort(&vlp1, &vlp2); 1415 1416 if (vlp1 != NULL) { 1417 mtx_lock(vlp1); 1418 cel->vlp[0] = vlp1; 1419 } 1420 mtx_lock(vlp2); 1421 cel->vlp[1] = vlp2; 1422 } 1423 1424 static void 1425 cache_unlock_vnodes_cel(struct celockstate *cel) 1426 { 1427 1428 MPASS(cel->vlp[0] != NULL || cel->vlp[1] != NULL); 1429 1430 if (cel->vlp[0] != NULL) 1431 mtx_unlock(cel->vlp[0]); 1432 if (cel->vlp[1] != NULL) 1433 mtx_unlock(cel->vlp[1]); 1434 if (cel->vlp[2] != NULL) 1435 mtx_unlock(cel->vlp[2]); 1436 } 1437 1438 static bool 1439 cache_lock_vnodes_cel_3(struct celockstate *cel, struct vnode *vp) 1440 { 1441 struct mtx *vlp; 1442 bool ret; 1443 1444 cache_assert_vlp_locked(cel->vlp[0]); 1445 cache_assert_vlp_locked(cel->vlp[1]); 1446 MPASS(cel->vlp[2] == NULL); 1447 1448 MPASS(vp != NULL); 1449 vlp = VP2VNODELOCK(vp); 1450 1451 ret = true; 1452 if (vlp >= cel->vlp[1]) { 1453 mtx_lock(vlp); 1454 } else { 1455 if (mtx_trylock(vlp)) 1456 goto out; 1457 cache_lock_vnodes_cel_3_failures++; 1458 cache_unlock_vnodes_cel(cel); 1459 if (vlp < cel->vlp[0]) { 1460 mtx_lock(vlp); 1461 mtx_lock(cel->vlp[0]); 1462 mtx_lock(cel->vlp[1]); 1463 } else { 1464 if (cel->vlp[0] != NULL) 1465 mtx_lock(cel->vlp[0]); 1466 mtx_lock(vlp); 1467 mtx_lock(cel->vlp[1]); 1468 } 1469 ret = false; 1470 } 1471 out: 1472 cel->vlp[2] = vlp; 1473 return (ret); 1474 } 1475 1476 static void 1477 cache_lock_buckets_cel(struct celockstate *cel, struct rwlock *blp1, 1478 struct rwlock *blp2) 1479 { 1480 1481 MPASS(cel->blp[0] == NULL); 1482 MPASS(cel->blp[1] == NULL); 1483 1484 cache_sort(&blp1, &blp2); 1485 1486 if (blp1 != NULL) { 1487 rw_wlock(blp1); 1488 cel->blp[0] = blp1; 1489 } 1490 rw_wlock(blp2); 1491 cel->blp[1] = blp2; 1492 } 1493 1494 static void 1495 cache_unlock_buckets_cel(struct celockstate *cel) 1496 { 1497 1498 if (cel->blp[0] != NULL) 1499 rw_wunlock(cel->blp[0]); 1500 rw_wunlock(cel->blp[1]); 1501 } 1502 1503 /* 1504 * Lock part of the cache affected by the insertion. 1505 * 1506 * This means vnodelocks for dvp, vp and the relevant bucketlock. 1507 * However, insertion can result in removal of an old entry. In this 1508 * case we have an additional vnode and bucketlock pair to lock. If the 1509 * entry is negative, ncelock is locked instead of the vnode. 1510 * 1511 * That is, in the worst case we have to lock 3 vnodes and 2 bucketlocks, while 1512 * preserving the locking order (smaller address first). 1513 */ 1514 static void 1515 cache_enter_lock(struct celockstate *cel, struct vnode *dvp, struct vnode *vp, 1516 uint32_t hash) 1517 { 1518 struct namecache *ncp; 1519 struct rwlock *blps[2]; 1520 1521 blps[0] = HASH2BUCKETLOCK(hash); 1522 for (;;) { 1523 blps[1] = NULL; 1524 cache_lock_vnodes_cel(cel, dvp, vp); 1525 if (vp == NULL || vp->v_type != VDIR) 1526 break; 1527 ncp = vp->v_cache_dd; 1528 if (ncp == NULL) 1529 break; 1530 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 1531 break; 1532 MPASS(ncp->nc_dvp == vp); 1533 blps[1] = NCP2BUCKETLOCK(ncp); 1534 if (ncp->nc_flag & NCF_NEGATIVE) 1535 break; 1536 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp)) 1537 break; 1538 /* 1539 * All vnodes got re-locked. Re-validate the state and if 1540 * nothing changed we are done. Otherwise restart. 1541 */ 1542 if (ncp == vp->v_cache_dd && 1543 (ncp->nc_flag & NCF_ISDOTDOT) != 0 && 1544 blps[1] == NCP2BUCKETLOCK(ncp) && 1545 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2]) 1546 break; 1547 cache_unlock_vnodes_cel(cel); 1548 cel->vlp[0] = NULL; 1549 cel->vlp[1] = NULL; 1550 cel->vlp[2] = NULL; 1551 } 1552 cache_lock_buckets_cel(cel, blps[0], blps[1]); 1553 } 1554 1555 static void 1556 cache_enter_lock_dd(struct celockstate *cel, struct vnode *dvp, struct vnode *vp, 1557 uint32_t hash) 1558 { 1559 struct namecache *ncp; 1560 struct rwlock *blps[2]; 1561 1562 blps[0] = HASH2BUCKETLOCK(hash); 1563 for (;;) { 1564 blps[1] = NULL; 1565 cache_lock_vnodes_cel(cel, dvp, vp); 1566 ncp = dvp->v_cache_dd; 1567 if (ncp == NULL) 1568 break; 1569 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 1570 break; 1571 MPASS(ncp->nc_dvp == dvp); 1572 blps[1] = NCP2BUCKETLOCK(ncp); 1573 if (ncp->nc_flag & NCF_NEGATIVE) 1574 break; 1575 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp)) 1576 break; 1577 if (ncp == dvp->v_cache_dd && 1578 (ncp->nc_flag & NCF_ISDOTDOT) != 0 && 1579 blps[1] == NCP2BUCKETLOCK(ncp) && 1580 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2]) 1581 break; 1582 cache_unlock_vnodes_cel(cel); 1583 cel->vlp[0] = NULL; 1584 cel->vlp[1] = NULL; 1585 cel->vlp[2] = NULL; 1586 } 1587 cache_lock_buckets_cel(cel, blps[0], blps[1]); 1588 } 1589 1590 static void 1591 cache_enter_unlock(struct celockstate *cel) 1592 { 1593 1594 cache_unlock_buckets_cel(cel); 1595 cache_unlock_vnodes_cel(cel); 1596 } 1597 1598 /* 1599 * Add an entry to the cache. 1600 */ 1601 void 1602 cache_enter_time(struct vnode *dvp, struct vnode *vp, struct componentname *cnp, 1603 struct timespec *tsp, struct timespec *dtsp) 1604 { 1605 struct celockstate cel; 1606 struct namecache *ncp, *n2, *ndd; 1607 struct namecache_ts *ncp_ts, *n2_ts; 1608 struct nchashhead *ncpp; 1609 struct neglist *neglist; 1610 uint32_t hash; 1611 int flag; 1612 int len; 1613 bool neg_locked; 1614 int lnumcache; 1615 1616 CTR3(KTR_VFS, "cache_enter(%p, %p, %s)", dvp, vp, cnp->cn_nameptr); 1617 VNASSERT(vp == NULL || (vp->v_iflag & VI_DOOMED) == 0, vp, 1618 ("cache_enter: Adding a doomed vnode")); 1619 VNASSERT(dvp == NULL || (dvp->v_iflag & VI_DOOMED) == 0, dvp, 1620 ("cache_enter: Doomed vnode used as src")); 1621 1622 if (__predict_false(!doingcache)) 1623 return; 1624 1625 /* 1626 * Avoid blowout in namecache entries. 1627 */ 1628 if (__predict_false(numcache >= desiredvnodes * ncsizefactor)) 1629 return; 1630 1631 cache_celockstate_init(&cel); 1632 ndd = NULL; 1633 ncp_ts = NULL; 1634 flag = 0; 1635 if (cnp->cn_nameptr[0] == '.') { 1636 if (cnp->cn_namelen == 1) 1637 return; 1638 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 1639 len = cnp->cn_namelen; 1640 hash = cache_get_hash(cnp->cn_nameptr, len, dvp); 1641 cache_enter_lock_dd(&cel, dvp, vp, hash); 1642 /* 1643 * If dotdot entry already exists, just retarget it 1644 * to new parent vnode, otherwise continue with new 1645 * namecache entry allocation. 1646 */ 1647 if ((ncp = dvp->v_cache_dd) != NULL && 1648 ncp->nc_flag & NCF_ISDOTDOT) { 1649 KASSERT(ncp->nc_dvp == dvp, 1650 ("wrong isdotdot parent")); 1651 neg_locked = false; 1652 if (ncp->nc_flag & NCF_NEGATIVE || vp == NULL) { 1653 neglist = NCP2NEGLIST(ncp); 1654 mtx_lock(&ncneg_hot.nl_lock); 1655 mtx_lock(&neglist->nl_lock); 1656 neg_locked = true; 1657 } 1658 if (!(ncp->nc_flag & NCF_NEGATIVE)) { 1659 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, 1660 ncp, nc_dst); 1661 } else { 1662 cache_negative_remove(ncp, true); 1663 } 1664 if (vp != NULL) { 1665 TAILQ_INSERT_HEAD(&vp->v_cache_dst, 1666 ncp, nc_dst); 1667 ncp->nc_flag &= ~(NCF_NEGATIVE|NCF_HOTNEGATIVE); 1668 } else { 1669 ncp->nc_flag &= ~(NCF_HOTNEGATIVE); 1670 ncp->nc_flag |= NCF_NEGATIVE; 1671 cache_negative_insert(ncp, true); 1672 } 1673 if (neg_locked) { 1674 mtx_unlock(&neglist->nl_lock); 1675 mtx_unlock(&ncneg_hot.nl_lock); 1676 } 1677 ncp->nc_vp = vp; 1678 cache_enter_unlock(&cel); 1679 return; 1680 } 1681 dvp->v_cache_dd = NULL; 1682 cache_enter_unlock(&cel); 1683 cache_celockstate_init(&cel); 1684 SDT_PROBE3(vfs, namecache, enter, done, dvp, "..", vp); 1685 flag = NCF_ISDOTDOT; 1686 } 1687 } 1688 1689 /* 1690 * Calculate the hash key and setup as much of the new 1691 * namecache entry as possible before acquiring the lock. 1692 */ 1693 ncp = cache_alloc(cnp->cn_namelen, tsp != NULL); 1694 ncp->nc_flag = flag; 1695 ncp->nc_vp = vp; 1696 if (vp == NULL) 1697 ncp->nc_flag |= NCF_NEGATIVE; 1698 ncp->nc_dvp = dvp; 1699 if (tsp != NULL) { 1700 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); 1701 ncp_ts->nc_time = *tsp; 1702 ncp_ts->nc_ticks = ticks; 1703 ncp_ts->nc_nc.nc_flag |= NCF_TS; 1704 if (dtsp != NULL) { 1705 ncp_ts->nc_dotdottime = *dtsp; 1706 ncp_ts->nc_nc.nc_flag |= NCF_DTS; 1707 } 1708 } 1709 len = ncp->nc_nlen = cnp->cn_namelen; 1710 hash = cache_get_hash(cnp->cn_nameptr, len, dvp); 1711 strlcpy(ncp->nc_name, cnp->cn_nameptr, len + 1); 1712 cache_enter_lock(&cel, dvp, vp, hash); 1713 1714 /* 1715 * See if this vnode or negative entry is already in the cache 1716 * with this name. This can happen with concurrent lookups of 1717 * the same path name. 1718 */ 1719 ncpp = NCHHASH(hash); 1720 LIST_FOREACH(n2, ncpp, nc_hash) { 1721 if (n2->nc_dvp == dvp && 1722 n2->nc_nlen == cnp->cn_namelen && 1723 !bcmp(n2->nc_name, cnp->cn_nameptr, n2->nc_nlen)) { 1724 if (tsp != NULL) { 1725 KASSERT((n2->nc_flag & NCF_TS) != 0, 1726 ("no NCF_TS")); 1727 n2_ts = __containerof(n2, struct namecache_ts, nc_nc); 1728 n2_ts->nc_time = ncp_ts->nc_time; 1729 n2_ts->nc_ticks = ncp_ts->nc_ticks; 1730 if (dtsp != NULL) { 1731 n2_ts->nc_dotdottime = ncp_ts->nc_dotdottime; 1732 if (ncp->nc_flag & NCF_NEGATIVE) 1733 mtx_lock(&ncneg_hot.nl_lock); 1734 n2_ts->nc_nc.nc_flag |= NCF_DTS; 1735 if (ncp->nc_flag & NCF_NEGATIVE) 1736 mtx_unlock(&ncneg_hot.nl_lock); 1737 } 1738 } 1739 goto out_unlock_free; 1740 } 1741 } 1742 1743 if (flag == NCF_ISDOTDOT) { 1744 /* 1745 * See if we are trying to add .. entry, but some other lookup 1746 * has populated v_cache_dd pointer already. 1747 */ 1748 if (dvp->v_cache_dd != NULL) 1749 goto out_unlock_free; 1750 KASSERT(vp == NULL || vp->v_type == VDIR, 1751 ("wrong vnode type %p", vp)); 1752 dvp->v_cache_dd = ncp; 1753 } 1754 1755 if (vp != NULL) { 1756 if (vp->v_type == VDIR) { 1757 if (flag != NCF_ISDOTDOT) { 1758 /* 1759 * For this case, the cache entry maps both the 1760 * directory name in it and the name ".." for the 1761 * directory's parent. 1762 */ 1763 if ((ndd = vp->v_cache_dd) != NULL) { 1764 if ((ndd->nc_flag & NCF_ISDOTDOT) != 0) 1765 cache_zap_locked(ndd, false); 1766 else 1767 ndd = NULL; 1768 } 1769 vp->v_cache_dd = ncp; 1770 } 1771 } else { 1772 vp->v_cache_dd = NULL; 1773 } 1774 } 1775 1776 if (flag != NCF_ISDOTDOT) { 1777 if (LIST_EMPTY(&dvp->v_cache_src)) { 1778 vhold(dvp); 1779 atomic_add_rel_long(&numcachehv, 1); 1780 } 1781 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); 1782 } 1783 1784 /* 1785 * Insert the new namecache entry into the appropriate chain 1786 * within the cache entries table. 1787 */ 1788 LIST_INSERT_HEAD(ncpp, ncp, nc_hash); 1789 1790 /* 1791 * If the entry is "negative", we place it into the 1792 * "negative" cache queue, otherwise, we place it into the 1793 * destination vnode's cache entries queue. 1794 */ 1795 if (vp != NULL) { 1796 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); 1797 SDT_PROBE3(vfs, namecache, enter, done, dvp, ncp->nc_name, 1798 vp); 1799 } else { 1800 if (cnp->cn_flags & ISWHITEOUT) 1801 ncp->nc_flag |= NCF_WHITE; 1802 cache_negative_insert(ncp, false); 1803 SDT_PROBE2(vfs, namecache, enter_negative, done, dvp, 1804 ncp->nc_name); 1805 } 1806 cache_enter_unlock(&cel); 1807 lnumcache = atomic_fetchadd_long(&numcache, 1) + 1; 1808 if (numneg * ncnegfactor > lnumcache) 1809 cache_negative_zap_one(); 1810 cache_free(ndd); 1811 return; 1812 out_unlock_free: 1813 cache_enter_unlock(&cel); 1814 cache_free(ncp); 1815 return; 1816 } 1817 1818 static u_int 1819 cache_roundup_2(u_int val) 1820 { 1821 u_int res; 1822 1823 for (res = 1; res <= val; res <<= 1) 1824 continue; 1825 1826 return (res); 1827 } 1828 1829 /* 1830 * Name cache initialization, from vfs_init() when we are booting 1831 */ 1832 static void 1833 nchinit(void *dummy __unused) 1834 { 1835 u_int i; 1836 1837 cache_zone_small = uma_zcreate("S VFS Cache", 1838 sizeof(struct namecache) + CACHE_PATH_CUTOFF + 1, 1839 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache), 1840 UMA_ZONE_ZINIT); 1841 cache_zone_small_ts = uma_zcreate("STS VFS Cache", 1842 sizeof(struct namecache_ts) + CACHE_PATH_CUTOFF + 1, 1843 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache_ts), 1844 UMA_ZONE_ZINIT); 1845 cache_zone_large = uma_zcreate("L VFS Cache", 1846 sizeof(struct namecache) + NAME_MAX + 1, 1847 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache), 1848 UMA_ZONE_ZINIT); 1849 cache_zone_large_ts = uma_zcreate("LTS VFS Cache", 1850 sizeof(struct namecache_ts) + NAME_MAX + 1, 1851 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache_ts), 1852 UMA_ZONE_ZINIT); 1853 1854 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash); 1855 ncbuckethash = cache_roundup_2(mp_ncpus * 64) - 1; 1856 if (ncbuckethash > nchash) 1857 ncbuckethash = nchash; 1858 bucketlocks = malloc(sizeof(*bucketlocks) * numbucketlocks, M_VFSCACHE, 1859 M_WAITOK | M_ZERO); 1860 for (i = 0; i < numbucketlocks; i++) 1861 rw_init_flags(&bucketlocks[i], "ncbuc", RW_DUPOK | RW_RECURSE); 1862 ncvnodehash = cache_roundup_2(mp_ncpus * 64) - 1; 1863 vnodelocks = malloc(sizeof(*vnodelocks) * numvnodelocks, M_VFSCACHE, 1864 M_WAITOK | M_ZERO); 1865 for (i = 0; i < numvnodelocks; i++) 1866 mtx_init(&vnodelocks[i], "ncvn", NULL, MTX_DUPOK | MTX_RECURSE); 1867 ncpurgeminvnodes = numbucketlocks; 1868 1869 ncneghash = 3; 1870 neglists = malloc(sizeof(*neglists) * numneglists, M_VFSCACHE, 1871 M_WAITOK | M_ZERO); 1872 for (i = 0; i < numneglists; i++) { 1873 mtx_init(&neglists[i].nl_lock, "ncnegl", NULL, MTX_DEF); 1874 TAILQ_INIT(&neglists[i].nl_list); 1875 } 1876 mtx_init(&ncneg_hot.nl_lock, "ncneglh", NULL, MTX_DEF); 1877 TAILQ_INIT(&ncneg_hot.nl_list); 1878 1879 mtx_init(&ncneg_shrink_lock, "ncnegs", NULL, MTX_DEF); 1880 1881 numcalls = counter_u64_alloc(M_WAITOK); 1882 dothits = counter_u64_alloc(M_WAITOK); 1883 dotdothits = counter_u64_alloc(M_WAITOK); 1884 numchecks = counter_u64_alloc(M_WAITOK); 1885 nummiss = counter_u64_alloc(M_WAITOK); 1886 nummisszap = counter_u64_alloc(M_WAITOK); 1887 numposzaps = counter_u64_alloc(M_WAITOK); 1888 numposhits = counter_u64_alloc(M_WAITOK); 1889 numnegzaps = counter_u64_alloc(M_WAITOK); 1890 numneghits = counter_u64_alloc(M_WAITOK); 1891 numfullpathcalls = counter_u64_alloc(M_WAITOK); 1892 numfullpathfail1 = counter_u64_alloc(M_WAITOK); 1893 numfullpathfail2 = counter_u64_alloc(M_WAITOK); 1894 numfullpathfail4 = counter_u64_alloc(M_WAITOK); 1895 numfullpathfound = counter_u64_alloc(M_WAITOK); 1896 } 1897 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL); 1898 1899 void 1900 cache_changesize(int newmaxvnodes) 1901 { 1902 struct nchashhead *new_nchashtbl, *old_nchashtbl; 1903 u_long new_nchash, old_nchash; 1904 struct namecache *ncp; 1905 uint32_t hash; 1906 int i; 1907 1908 newmaxvnodes = cache_roundup_2(newmaxvnodes * 2); 1909 if (newmaxvnodes < numbucketlocks) 1910 newmaxvnodes = numbucketlocks; 1911 1912 new_nchashtbl = hashinit(newmaxvnodes, M_VFSCACHE, &new_nchash); 1913 /* If same hash table size, nothing to do */ 1914 if (nchash == new_nchash) { 1915 free(new_nchashtbl, M_VFSCACHE); 1916 return; 1917 } 1918 /* 1919 * Move everything from the old hash table to the new table. 1920 * None of the namecache entries in the table can be removed 1921 * because to do so, they have to be removed from the hash table. 1922 */ 1923 cache_lock_all_vnodes(); 1924 cache_lock_all_buckets(); 1925 old_nchashtbl = nchashtbl; 1926 old_nchash = nchash; 1927 nchashtbl = new_nchashtbl; 1928 nchash = new_nchash; 1929 for (i = 0; i <= old_nchash; i++) { 1930 while ((ncp = LIST_FIRST(&old_nchashtbl[i])) != NULL) { 1931 hash = cache_get_hash(ncp->nc_name, ncp->nc_nlen, 1932 ncp->nc_dvp); 1933 LIST_REMOVE(ncp, nc_hash); 1934 LIST_INSERT_HEAD(NCHHASH(hash), ncp, nc_hash); 1935 } 1936 } 1937 cache_unlock_all_buckets(); 1938 cache_unlock_all_vnodes(); 1939 free(old_nchashtbl, M_VFSCACHE); 1940 } 1941 1942 /* 1943 * Invalidate all entries to a particular vnode. 1944 */ 1945 void 1946 cache_purge(struct vnode *vp) 1947 { 1948 TAILQ_HEAD(, namecache) ncps; 1949 struct namecache *ncp, *nnp; 1950 struct mtx *vlp, *vlp2; 1951 1952 CTR1(KTR_VFS, "cache_purge(%p)", vp); 1953 SDT_PROBE1(vfs, namecache, purge, done, vp); 1954 if (LIST_EMPTY(&vp->v_cache_src) && TAILQ_EMPTY(&vp->v_cache_dst) && 1955 vp->v_cache_dd == NULL) 1956 return; 1957 TAILQ_INIT(&ncps); 1958 vlp = VP2VNODELOCK(vp); 1959 vlp2 = NULL; 1960 mtx_lock(vlp); 1961 retry: 1962 while (!LIST_EMPTY(&vp->v_cache_src)) { 1963 ncp = LIST_FIRST(&vp->v_cache_src); 1964 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 1965 goto retry; 1966 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 1967 } 1968 while (!TAILQ_EMPTY(&vp->v_cache_dst)) { 1969 ncp = TAILQ_FIRST(&vp->v_cache_dst); 1970 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 1971 goto retry; 1972 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 1973 } 1974 ncp = vp->v_cache_dd; 1975 if (ncp != NULL) { 1976 KASSERT(ncp->nc_flag & NCF_ISDOTDOT, 1977 ("lost dotdot link")); 1978 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 1979 goto retry; 1980 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 1981 } 1982 KASSERT(vp->v_cache_dd == NULL, ("incomplete purge")); 1983 mtx_unlock(vlp); 1984 if (vlp2 != NULL) 1985 mtx_unlock(vlp2); 1986 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { 1987 cache_free(ncp); 1988 } 1989 } 1990 1991 /* 1992 * Invalidate all negative entries for a particular directory vnode. 1993 */ 1994 void 1995 cache_purge_negative(struct vnode *vp) 1996 { 1997 TAILQ_HEAD(, namecache) ncps; 1998 struct namecache *ncp, *nnp; 1999 struct mtx *vlp; 2000 2001 CTR1(KTR_VFS, "cache_purge_negative(%p)", vp); 2002 SDT_PROBE1(vfs, namecache, purge_negative, done, vp); 2003 if (LIST_EMPTY(&vp->v_cache_src)) 2004 return; 2005 TAILQ_INIT(&ncps); 2006 vlp = VP2VNODELOCK(vp); 2007 mtx_lock(vlp); 2008 LIST_FOREACH_SAFE(ncp, &vp->v_cache_src, nc_src, nnp) { 2009 if (!(ncp->nc_flag & NCF_NEGATIVE)) 2010 continue; 2011 cache_zap_negative_locked_vnode_kl(ncp, vp); 2012 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 2013 } 2014 mtx_unlock(vlp); 2015 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { 2016 cache_free(ncp); 2017 } 2018 } 2019 2020 /* 2021 * Flush all entries referencing a particular filesystem. 2022 */ 2023 void 2024 cache_purgevfs(struct mount *mp, bool force) 2025 { 2026 TAILQ_HEAD(, namecache) ncps; 2027 struct mtx *vlp1, *vlp2; 2028 struct rwlock *blp; 2029 struct nchashhead *bucket; 2030 struct namecache *ncp, *nnp; 2031 u_long i, j, n_nchash; 2032 int error; 2033 2034 /* Scan hash tables for applicable entries */ 2035 SDT_PROBE1(vfs, namecache, purgevfs, done, mp); 2036 if (!force && mp->mnt_nvnodelistsize <= ncpurgeminvnodes) 2037 return; 2038 TAILQ_INIT(&ncps); 2039 n_nchash = nchash + 1; 2040 vlp1 = vlp2 = NULL; 2041 for (i = 0; i < numbucketlocks; i++) { 2042 blp = (struct rwlock *)&bucketlocks[i]; 2043 rw_wlock(blp); 2044 for (j = i; j < n_nchash; j += numbucketlocks) { 2045 retry: 2046 bucket = &nchashtbl[j]; 2047 LIST_FOREACH_SAFE(ncp, bucket, nc_hash, nnp) { 2048 cache_assert_bucket_locked(ncp, RA_WLOCKED); 2049 if (ncp->nc_dvp->v_mount != mp) 2050 continue; 2051 error = cache_zap_wlocked_bucket_kl(ncp, blp, 2052 &vlp1, &vlp2); 2053 if (error != 0) 2054 goto retry; 2055 TAILQ_INSERT_HEAD(&ncps, ncp, nc_dst); 2056 } 2057 } 2058 rw_wunlock(blp); 2059 if (vlp1 == NULL && vlp2 == NULL) 2060 cache_maybe_yield(); 2061 } 2062 if (vlp1 != NULL) 2063 mtx_unlock(vlp1); 2064 if (vlp2 != NULL) 2065 mtx_unlock(vlp2); 2066 2067 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { 2068 cache_free(ncp); 2069 } 2070 } 2071 2072 /* 2073 * Perform canonical checks and cache lookup and pass on to filesystem 2074 * through the vop_cachedlookup only if needed. 2075 */ 2076 2077 int 2078 vfs_cache_lookup(struct vop_lookup_args *ap) 2079 { 2080 struct vnode *dvp; 2081 int error; 2082 struct vnode **vpp = ap->a_vpp; 2083 struct componentname *cnp = ap->a_cnp; 2084 struct ucred *cred = cnp->cn_cred; 2085 int flags = cnp->cn_flags; 2086 struct thread *td = cnp->cn_thread; 2087 2088 *vpp = NULL; 2089 dvp = ap->a_dvp; 2090 2091 if (dvp->v_type != VDIR) 2092 return (ENOTDIR); 2093 2094 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && 2095 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 2096 return (EROFS); 2097 2098 error = VOP_ACCESS(dvp, VEXEC, cred, td); 2099 if (error) 2100 return (error); 2101 2102 error = cache_lookup(dvp, vpp, cnp, NULL, NULL); 2103 if (error == 0) 2104 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); 2105 if (error == -1) 2106 return (0); 2107 return (error); 2108 } 2109 2110 /* 2111 * XXX All of these sysctls would probably be more productive dead. 2112 */ 2113 static int __read_mostly disablecwd; 2114 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, 2115 "Disable the getcwd syscall"); 2116 2117 /* Implementation of the getcwd syscall. */ 2118 int 2119 sys___getcwd(struct thread *td, struct __getcwd_args *uap) 2120 { 2121 2122 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen, 2123 MAXPATHLEN)); 2124 } 2125 2126 int 2127 kern___getcwd(struct thread *td, char *buf, enum uio_seg bufseg, size_t buflen, 2128 size_t path_max) 2129 { 2130 char *bp, *tmpbuf; 2131 struct filedesc *fdp; 2132 struct vnode *cdir, *rdir; 2133 int error; 2134 2135 if (__predict_false(disablecwd)) 2136 return (ENODEV); 2137 if (__predict_false(buflen < 2)) 2138 return (EINVAL); 2139 if (buflen > path_max) 2140 buflen = path_max; 2141 2142 tmpbuf = malloc(buflen, M_TEMP, M_WAITOK); 2143 fdp = td->td_proc->p_fd; 2144 FILEDESC_SLOCK(fdp); 2145 cdir = fdp->fd_cdir; 2146 vrefact(cdir); 2147 rdir = fdp->fd_rdir; 2148 vrefact(rdir); 2149 FILEDESC_SUNLOCK(fdp); 2150 error = vn_fullpath1(td, cdir, rdir, tmpbuf, &bp, buflen); 2151 vrele(rdir); 2152 vrele(cdir); 2153 2154 if (!error) { 2155 if (bufseg == UIO_SYSSPACE) 2156 bcopy(bp, buf, strlen(bp) + 1); 2157 else 2158 error = copyout(bp, buf, strlen(bp) + 1); 2159 #ifdef KTRACE 2160 if (KTRPOINT(curthread, KTR_NAMEI)) 2161 ktrnamei(bp); 2162 #endif 2163 } 2164 free(tmpbuf, M_TEMP); 2165 return (error); 2166 } 2167 2168 /* 2169 * Thus begins the fullpath magic. 2170 */ 2171 2172 static int __read_mostly disablefullpath; 2173 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0, 2174 "Disable the vn_fullpath function"); 2175 2176 /* 2177 * Retrieve the full filesystem path that correspond to a vnode from the name 2178 * cache (if available) 2179 */ 2180 int 2181 vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf) 2182 { 2183 char *buf; 2184 struct filedesc *fdp; 2185 struct vnode *rdir; 2186 int error; 2187 2188 if (__predict_false(disablefullpath)) 2189 return (ENODEV); 2190 if (__predict_false(vn == NULL)) 2191 return (EINVAL); 2192 2193 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 2194 fdp = td->td_proc->p_fd; 2195 FILEDESC_SLOCK(fdp); 2196 rdir = fdp->fd_rdir; 2197 vrefact(rdir); 2198 FILEDESC_SUNLOCK(fdp); 2199 error = vn_fullpath1(td, vn, rdir, buf, retbuf, MAXPATHLEN); 2200 vrele(rdir); 2201 2202 if (!error) 2203 *freebuf = buf; 2204 else 2205 free(buf, M_TEMP); 2206 return (error); 2207 } 2208 2209 /* 2210 * This function is similar to vn_fullpath, but it attempts to lookup the 2211 * pathname relative to the global root mount point. This is required for the 2212 * auditing sub-system, as audited pathnames must be absolute, relative to the 2213 * global root mount point. 2214 */ 2215 int 2216 vn_fullpath_global(struct thread *td, struct vnode *vn, 2217 char **retbuf, char **freebuf) 2218 { 2219 char *buf; 2220 int error; 2221 2222 if (__predict_false(disablefullpath)) 2223 return (ENODEV); 2224 if (__predict_false(vn == NULL)) 2225 return (EINVAL); 2226 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 2227 error = vn_fullpath1(td, vn, rootvnode, buf, retbuf, MAXPATHLEN); 2228 if (!error) 2229 *freebuf = buf; 2230 else 2231 free(buf, M_TEMP); 2232 return (error); 2233 } 2234 2235 int 2236 vn_vptocnp(struct vnode **vp, struct ucred *cred, char *buf, u_int *buflen) 2237 { 2238 struct vnode *dvp; 2239 struct namecache *ncp; 2240 struct mtx *vlp; 2241 int error; 2242 2243 vlp = VP2VNODELOCK(*vp); 2244 mtx_lock(vlp); 2245 TAILQ_FOREACH(ncp, &((*vp)->v_cache_dst), nc_dst) { 2246 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 2247 break; 2248 } 2249 if (ncp != NULL) { 2250 if (*buflen < ncp->nc_nlen) { 2251 mtx_unlock(vlp); 2252 vrele(*vp); 2253 counter_u64_add(numfullpathfail4, 1); 2254 error = ENOMEM; 2255 SDT_PROBE3(vfs, namecache, fullpath, return, error, 2256 vp, NULL); 2257 return (error); 2258 } 2259 *buflen -= ncp->nc_nlen; 2260 memcpy(buf + *buflen, ncp->nc_name, ncp->nc_nlen); 2261 SDT_PROBE3(vfs, namecache, fullpath, hit, ncp->nc_dvp, 2262 ncp->nc_name, vp); 2263 dvp = *vp; 2264 *vp = ncp->nc_dvp; 2265 vref(*vp); 2266 mtx_unlock(vlp); 2267 vrele(dvp); 2268 return (0); 2269 } 2270 SDT_PROBE1(vfs, namecache, fullpath, miss, vp); 2271 2272 mtx_unlock(vlp); 2273 vn_lock(*vp, LK_SHARED | LK_RETRY); 2274 error = VOP_VPTOCNP(*vp, &dvp, cred, buf, buflen); 2275 vput(*vp); 2276 if (error) { 2277 counter_u64_add(numfullpathfail2, 1); 2278 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); 2279 return (error); 2280 } 2281 2282 *vp = dvp; 2283 if (dvp->v_iflag & VI_DOOMED) { 2284 /* forced unmount */ 2285 vrele(dvp); 2286 error = ENOENT; 2287 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); 2288 return (error); 2289 } 2290 /* 2291 * *vp has its use count incremented still. 2292 */ 2293 2294 return (0); 2295 } 2296 2297 /* 2298 * The magic behind kern___getcwd() and vn_fullpath(). 2299 */ 2300 static int 2301 vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 2302 char *buf, char **retbuf, u_int buflen) 2303 { 2304 int error, slash_prefixed; 2305 #ifdef KDTRACE_HOOKS 2306 struct vnode *startvp = vp; 2307 #endif 2308 struct vnode *vp1; 2309 2310 buflen--; 2311 buf[buflen] = '\0'; 2312 error = 0; 2313 slash_prefixed = 0; 2314 2315 SDT_PROBE1(vfs, namecache, fullpath, entry, vp); 2316 counter_u64_add(numfullpathcalls, 1); 2317 vref(vp); 2318 if (vp->v_type != VDIR) { 2319 error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen); 2320 if (error) 2321 return (error); 2322 if (buflen == 0) { 2323 vrele(vp); 2324 return (ENOMEM); 2325 } 2326 buf[--buflen] = '/'; 2327 slash_prefixed = 1; 2328 } 2329 while (vp != rdir && vp != rootvnode) { 2330 /* 2331 * The vp vnode must be already fully constructed, 2332 * since it is either found in namecache or obtained 2333 * from VOP_VPTOCNP(). We may test for VV_ROOT safely 2334 * without obtaining the vnode lock. 2335 */ 2336 if ((vp->v_vflag & VV_ROOT) != 0) { 2337 vn_lock(vp, LK_RETRY | LK_SHARED); 2338 2339 /* 2340 * With the vnode locked, check for races with 2341 * unmount, forced or not. Note that we 2342 * already verified that vp is not equal to 2343 * the root vnode, which means that 2344 * mnt_vnodecovered can be NULL only for the 2345 * case of unmount. 2346 */ 2347 if ((vp->v_iflag & VI_DOOMED) != 0 || 2348 (vp1 = vp->v_mount->mnt_vnodecovered) == NULL || 2349 vp1->v_mountedhere != vp->v_mount) { 2350 vput(vp); 2351 error = ENOENT; 2352 SDT_PROBE3(vfs, namecache, fullpath, return, 2353 error, vp, NULL); 2354 break; 2355 } 2356 2357 vref(vp1); 2358 vput(vp); 2359 vp = vp1; 2360 continue; 2361 } 2362 if (vp->v_type != VDIR) { 2363 vrele(vp); 2364 counter_u64_add(numfullpathfail1, 1); 2365 error = ENOTDIR; 2366 SDT_PROBE3(vfs, namecache, fullpath, return, 2367 error, vp, NULL); 2368 break; 2369 } 2370 error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen); 2371 if (error) 2372 break; 2373 if (buflen == 0) { 2374 vrele(vp); 2375 error = ENOMEM; 2376 SDT_PROBE3(vfs, namecache, fullpath, return, error, 2377 startvp, NULL); 2378 break; 2379 } 2380 buf[--buflen] = '/'; 2381 slash_prefixed = 1; 2382 } 2383 if (error) 2384 return (error); 2385 if (!slash_prefixed) { 2386 if (buflen == 0) { 2387 vrele(vp); 2388 counter_u64_add(numfullpathfail4, 1); 2389 SDT_PROBE3(vfs, namecache, fullpath, return, ENOMEM, 2390 startvp, NULL); 2391 return (ENOMEM); 2392 } 2393 buf[--buflen] = '/'; 2394 } 2395 counter_u64_add(numfullpathfound, 1); 2396 vrele(vp); 2397 2398 SDT_PROBE3(vfs, namecache, fullpath, return, 0, startvp, buf + buflen); 2399 *retbuf = buf + buflen; 2400 return (0); 2401 } 2402 2403 struct vnode * 2404 vn_dir_dd_ino(struct vnode *vp) 2405 { 2406 struct namecache *ncp; 2407 struct vnode *ddvp; 2408 struct mtx *vlp; 2409 2410 ASSERT_VOP_LOCKED(vp, "vn_dir_dd_ino"); 2411 vlp = VP2VNODELOCK(vp); 2412 mtx_lock(vlp); 2413 TAILQ_FOREACH(ncp, &(vp->v_cache_dst), nc_dst) { 2414 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) 2415 continue; 2416 ddvp = ncp->nc_dvp; 2417 vhold(ddvp); 2418 mtx_unlock(vlp); 2419 if (vget(ddvp, LK_SHARED | LK_NOWAIT | LK_VNHELD, curthread)) 2420 return (NULL); 2421 return (ddvp); 2422 } 2423 mtx_unlock(vlp); 2424 return (NULL); 2425 } 2426 2427 int 2428 vn_commname(struct vnode *vp, char *buf, u_int buflen) 2429 { 2430 struct namecache *ncp; 2431 struct mtx *vlp; 2432 int l; 2433 2434 vlp = VP2VNODELOCK(vp); 2435 mtx_lock(vlp); 2436 TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst) 2437 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 2438 break; 2439 if (ncp == NULL) { 2440 mtx_unlock(vlp); 2441 return (ENOENT); 2442 } 2443 l = min(ncp->nc_nlen, buflen - 1); 2444 memcpy(buf, ncp->nc_name, l); 2445 mtx_unlock(vlp); 2446 buf[l] = '\0'; 2447 return (0); 2448 } 2449 2450 /* ABI compat shims for old kernel modules. */ 2451 #undef cache_enter 2452 2453 void cache_enter(struct vnode *dvp, struct vnode *vp, 2454 struct componentname *cnp); 2455 2456 void 2457 cache_enter(struct vnode *dvp, struct vnode *vp, struct componentname *cnp) 2458 { 2459 2460 cache_enter_time(dvp, vp, cnp, NULL, NULL); 2461 } 2462 2463 /* 2464 * This function updates path string to vnode's full global path 2465 * and checks the size of the new path string against the pathlen argument. 2466 * 2467 * Requires a locked, referenced vnode. 2468 * Vnode is re-locked on success or ENODEV, otherwise unlocked. 2469 * 2470 * If sysctl debug.disablefullpath is set, ENODEV is returned, 2471 * vnode is left locked and path remain untouched. 2472 * 2473 * If vp is a directory, the call to vn_fullpath_global() always succeeds 2474 * because it falls back to the ".." lookup if the namecache lookup fails. 2475 */ 2476 int 2477 vn_path_to_global_path(struct thread *td, struct vnode *vp, char *path, 2478 u_int pathlen) 2479 { 2480 struct nameidata nd; 2481 struct vnode *vp1; 2482 char *rpath, *fbuf; 2483 int error; 2484 2485 ASSERT_VOP_ELOCKED(vp, __func__); 2486 2487 /* Return ENODEV if sysctl debug.disablefullpath==1 */ 2488 if (__predict_false(disablefullpath)) 2489 return (ENODEV); 2490 2491 /* Construct global filesystem path from vp. */ 2492 VOP_UNLOCK(vp, 0); 2493 error = vn_fullpath_global(td, vp, &rpath, &fbuf); 2494 2495 if (error != 0) { 2496 vrele(vp); 2497 return (error); 2498 } 2499 2500 if (strlen(rpath) >= pathlen) { 2501 vrele(vp); 2502 error = ENAMETOOLONG; 2503 goto out; 2504 } 2505 2506 /* 2507 * Re-lookup the vnode by path to detect a possible rename. 2508 * As a side effect, the vnode is relocked. 2509 * If vnode was renamed, return ENOENT. 2510 */ 2511 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1, 2512 UIO_SYSSPACE, path, td); 2513 error = namei(&nd); 2514 if (error != 0) { 2515 vrele(vp); 2516 goto out; 2517 } 2518 NDFREE(&nd, NDF_ONLY_PNBUF); 2519 vp1 = nd.ni_vp; 2520 vrele(vp); 2521 if (vp1 == vp) 2522 strcpy(path, rpath); 2523 else { 2524 vput(vp1); 2525 error = ENOENT; 2526 } 2527 2528 out: 2529 free(fbuf, M_TEMP); 2530 return (error); 2531 } 2532