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