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_ddb.h" 41 #include "opt_ktrace.h" 42 43 #include <sys/param.h> 44 #include <sys/systm.h> 45 #include <sys/counter.h> 46 #include <sys/filedesc.h> 47 #include <sys/fnv_hash.h> 48 #include <sys/kernel.h> 49 #include <sys/lock.h> 50 #include <sys/malloc.h> 51 #include <sys/fcntl.h> 52 #include <sys/mount.h> 53 #include <sys/namei.h> 54 #include <sys/proc.h> 55 #include <sys/rwlock.h> 56 #include <sys/sdt.h> 57 #include <sys/smp.h> 58 #include <sys/syscallsubr.h> 59 #include <sys/sysctl.h> 60 #include <sys/sysproto.h> 61 #include <sys/vnode.h> 62 #ifdef KTRACE 63 #include <sys/ktrace.h> 64 #endif 65 66 #ifdef DDB 67 #include <ddb/ddb.h> 68 #endif 69 70 #include <vm/uma.h> 71 72 SDT_PROVIDER_DECLARE(vfs); 73 SDT_PROBE_DEFINE3(vfs, namecache, enter, done, "struct vnode *", "char *", 74 "struct vnode *"); 75 SDT_PROBE_DEFINE2(vfs, namecache, enter_negative, done, "struct vnode *", 76 "char *"); 77 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, entry, "struct vnode *"); 78 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, hit, "struct vnode *", 79 "char *", "struct vnode *"); 80 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, miss, "struct vnode *"); 81 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, return, "int", 82 "struct vnode *", "char *"); 83 SDT_PROBE_DEFINE3(vfs, namecache, lookup, hit, "struct vnode *", "char *", 84 "struct vnode *"); 85 SDT_PROBE_DEFINE2(vfs, namecache, lookup, hit__negative, 86 "struct vnode *", "char *"); 87 SDT_PROBE_DEFINE2(vfs, namecache, lookup, miss, "struct vnode *", 88 "char *"); 89 SDT_PROBE_DEFINE1(vfs, namecache, purge, done, "struct vnode *"); 90 SDT_PROBE_DEFINE1(vfs, namecache, purge_negative, done, "struct vnode *"); 91 SDT_PROBE_DEFINE1(vfs, namecache, purgevfs, done, "struct mount *"); 92 SDT_PROBE_DEFINE3(vfs, namecache, zap, done, "struct vnode *", "char *", 93 "struct vnode *"); 94 SDT_PROBE_DEFINE3(vfs, namecache, zap_negative, done, "struct vnode *", 95 "char *", "int"); 96 SDT_PROBE_DEFINE3(vfs, namecache, shrink_negative, done, "struct vnode *", 97 "char *", "int"); 98 99 /* 100 * This structure describes the elements in the cache of recent 101 * names looked up by namei. 102 */ 103 104 struct namecache { 105 LIST_ENTRY(namecache) nc_hash; /* hash chain */ 106 LIST_ENTRY(namecache) nc_src; /* source vnode list */ 107 TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */ 108 struct vnode *nc_dvp; /* vnode of parent of name */ 109 union { 110 struct vnode *nu_vp; /* vnode the name refers to */ 111 u_int nu_neghits; /* negative entry hits */ 112 } n_un; 113 u_char nc_flag; /* flag bits */ 114 u_char nc_nlen; /* length of name */ 115 char nc_name[0]; /* segment name + nul */ 116 }; 117 118 /* 119 * struct namecache_ts repeats struct namecache layout up to the 120 * nc_nlen member. 121 * struct namecache_ts is used in place of struct namecache when time(s) need 122 * to be stored. The nc_dotdottime field is used when a cache entry is mapping 123 * both a non-dotdot directory name plus dotdot for the directory's 124 * parent. 125 */ 126 struct namecache_ts { 127 struct timespec nc_time; /* timespec provided by fs */ 128 struct timespec nc_dotdottime; /* dotdot timespec provided by fs */ 129 int nc_ticks; /* ticks value when entry was added */ 130 struct namecache nc_nc; 131 }; 132 133 #define nc_vp n_un.nu_vp 134 #define nc_neghits n_un.nu_neghits 135 136 /* 137 * Flags in namecache.nc_flag 138 */ 139 #define NCF_WHITE 0x01 140 #define NCF_ISDOTDOT 0x02 141 #define NCF_TS 0x04 142 #define NCF_DTS 0x08 143 #define NCF_DVDROP 0x10 144 #define NCF_NEGATIVE 0x20 145 #define NCF_HOTNEGATIVE 0x40 146 147 /* 148 * Name caching works as follows: 149 * 150 * Names found by directory scans are retained in a cache 151 * for future reference. It is managed LRU, so frequently 152 * used names will hang around. Cache is indexed by hash value 153 * obtained from (dvp, name) where dvp refers to the directory 154 * containing name. 155 * 156 * If it is a "negative" entry, (i.e. for a name that is known NOT to 157 * exist) the vnode pointer will be NULL. 158 * 159 * Upon reaching the last segment of a path, if the reference 160 * is for DELETE, or NOCACHE is set (rewrite), and the 161 * name is located in the cache, it will be dropped. 162 * 163 * These locks are used (in the order in which they can be taken): 164 * NAME TYPE ROLE 165 * vnodelock mtx vnode lists and v_cache_dd field protection 166 * bucketlock rwlock for access to given set of hash buckets 167 * neglist mtx negative entry LRU management 168 * 169 * Additionally, ncneg_shrink_lock mtx is used to have at most one thread 170 * shrinking the LRU list. 171 * 172 * It is legal to take multiple vnodelock and bucketlock locks. The locking 173 * order is lower address first. Both are recursive. 174 * 175 * "." lookups are lockless. 176 * 177 * ".." and vnode -> name lookups require vnodelock. 178 * 179 * name -> vnode lookup requires the relevant bucketlock to be held for reading. 180 * 181 * Insertions and removals of entries require involved vnodes and bucketlocks 182 * to be write-locked to prevent other threads from seeing the entry. 183 * 184 * Some lookups result in removal of the found entry (e.g. getting rid of a 185 * negative entry with the intent to create a positive one), which poses a 186 * problem when multiple threads reach the state. Similarly, two different 187 * threads can purge two different vnodes and try to remove the same name. 188 * 189 * If the already held vnode lock is lower than the second required lock, we 190 * can just take the other lock. However, in the opposite case, this could 191 * deadlock. As such, this is resolved by trylocking and if that fails unlocking 192 * the first node, locking everything in order and revalidating the state. 193 */ 194 195 /* 196 * Structures associated with name caching. 197 */ 198 #define NCHHASH(hash) \ 199 (&nchashtbl[(hash) & nchash]) 200 static __read_mostly LIST_HEAD(nchashhead, namecache) *nchashtbl;/* Hash Table */ 201 static u_long __read_mostly nchash; /* size of hash table */ 202 SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, 203 "Size of namecache hash table"); 204 static u_long __read_mostly ncnegfactor = 12; /* ratio of negative entries */ 205 SYSCTL_ULONG(_vfs, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, 206 "Ratio of negative namecache entries"); 207 static u_long __exclusive_cache_line numneg; /* number of negative entries allocated */ 208 SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, 209 "Number of negative entries in namecache"); 210 static u_long __exclusive_cache_line numcache;/* number of cache entries allocated */ 211 SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, 212 "Number of namecache entries"); 213 static u_long __exclusive_cache_line numcachehv;/* number of cache entries with vnodes held */ 214 SYSCTL_ULONG(_debug, OID_AUTO, numcachehv, CTLFLAG_RD, &numcachehv, 0, 215 "Number of namecache entries with vnodes held"); 216 u_int __read_mostly ncsizefactor = 2; 217 SYSCTL_UINT(_vfs, OID_AUTO, ncsizefactor, CTLFLAG_RW, &ncsizefactor, 0, 218 "Size factor for namecache"); 219 static u_int __read_mostly ncpurgeminvnodes; 220 SYSCTL_UINT(_vfs, OID_AUTO, ncpurgeminvnodes, CTLFLAG_RW, &ncpurgeminvnodes, 0, 221 "Number of vnodes below which purgevfs ignores the request"); 222 static u_int __read_mostly ncneghitsrequeue = 8; 223 SYSCTL_UINT(_vfs, OID_AUTO, ncneghitsrequeue, CTLFLAG_RW, &ncneghitsrequeue, 0, 224 "Number of hits to requeue a negative entry in the LRU list"); 225 226 struct nchstats nchstats; /* cache effectiveness statistics */ 227 228 static struct mtx ncneg_shrink_lock; 229 static int shrink_list_turn; 230 231 struct neglist { 232 struct mtx nl_lock; 233 TAILQ_HEAD(, namecache) nl_list; 234 } __aligned(CACHE_LINE_SIZE); 235 236 static struct neglist __read_mostly *neglists; 237 static struct neglist ncneg_hot; 238 239 #define numneglists (ncneghash + 1) 240 static u_int __read_mostly ncneghash; 241 static inline struct neglist * 242 NCP2NEGLIST(struct namecache *ncp) 243 { 244 245 return (&neglists[(((uintptr_t)(ncp) >> 8) & ncneghash)]); 246 } 247 248 #define numbucketlocks (ncbuckethash + 1) 249 static u_int __read_mostly ncbuckethash; 250 static struct rwlock_padalign __read_mostly *bucketlocks; 251 #define HASH2BUCKETLOCK(hash) \ 252 ((struct rwlock *)(&bucketlocks[((hash) & ncbuckethash)])) 253 254 #define numvnodelocks (ncvnodehash + 1) 255 static u_int __read_mostly ncvnodehash; 256 static struct mtx __read_mostly *vnodelocks; 257 static inline struct mtx * 258 VP2VNODELOCK(struct vnode *vp) 259 { 260 261 return (&vnodelocks[(((uintptr_t)(vp) >> 8) & ncvnodehash)]); 262 } 263 264 /* 265 * UMA zones for the VFS cache. 266 * 267 * The small cache is used for entries with short names, which are the 268 * most common. The large cache is used for entries which are too big to 269 * fit in the small cache. 270 */ 271 static uma_zone_t __read_mostly cache_zone_small; 272 static uma_zone_t __read_mostly cache_zone_small_ts; 273 static uma_zone_t __read_mostly cache_zone_large; 274 static uma_zone_t __read_mostly cache_zone_large_ts; 275 276 #define CACHE_PATH_CUTOFF 35 277 278 static struct namecache * 279 cache_alloc(int len, int ts) 280 { 281 struct namecache_ts *ncp_ts; 282 struct namecache *ncp; 283 284 if (__predict_false(ts)) { 285 if (len <= CACHE_PATH_CUTOFF) 286 ncp_ts = uma_zalloc(cache_zone_small_ts, M_WAITOK); 287 else 288 ncp_ts = uma_zalloc(cache_zone_large_ts, M_WAITOK); 289 ncp = &ncp_ts->nc_nc; 290 } else { 291 if (len <= CACHE_PATH_CUTOFF) 292 ncp = uma_zalloc(cache_zone_small, M_WAITOK); 293 else 294 ncp = uma_zalloc(cache_zone_large, M_WAITOK); 295 } 296 return (ncp); 297 } 298 299 static void 300 cache_free(struct namecache *ncp) 301 { 302 struct namecache_ts *ncp_ts; 303 304 if (ncp == NULL) 305 return; 306 if ((ncp->nc_flag & NCF_DVDROP) != 0) 307 vdrop(ncp->nc_dvp); 308 if (__predict_false(ncp->nc_flag & NCF_TS)) { 309 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); 310 if (ncp->nc_nlen <= CACHE_PATH_CUTOFF) 311 uma_zfree(cache_zone_small_ts, ncp_ts); 312 else 313 uma_zfree(cache_zone_large_ts, ncp_ts); 314 } else { 315 if (ncp->nc_nlen <= CACHE_PATH_CUTOFF) 316 uma_zfree(cache_zone_small, ncp); 317 else 318 uma_zfree(cache_zone_large, ncp); 319 } 320 } 321 322 static void 323 cache_out_ts(struct namecache *ncp, struct timespec *tsp, int *ticksp) 324 { 325 struct namecache_ts *ncp_ts; 326 327 KASSERT((ncp->nc_flag & NCF_TS) != 0 || 328 (tsp == NULL && ticksp == NULL), 329 ("No NCF_TS")); 330 331 if (tsp == NULL && ticksp == NULL) 332 return; 333 334 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); 335 if (tsp != NULL) 336 *tsp = ncp_ts->nc_time; 337 if (ticksp != NULL) 338 *ticksp = ncp_ts->nc_ticks; 339 } 340 341 static int __read_mostly doingcache = 1; /* 1 => enable the cache */ 342 SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0, 343 "VFS namecache enabled"); 344 345 /* Export size information to userland */ 346 SYSCTL_INT(_debug_sizeof, OID_AUTO, namecache, CTLFLAG_RD, SYSCTL_NULL_INT_PTR, 347 sizeof(struct namecache), "sizeof(struct namecache)"); 348 349 /* 350 * The new name cache statistics 351 */ 352 static SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, 353 "Name cache statistics"); 354 #define STATNODE_ULONG(name, descr) \ 355 SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, descr); 356 #define STATNODE_COUNTER(name, descr) \ 357 static counter_u64_t __read_mostly name; \ 358 SYSCTL_COUNTER_U64(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, descr); 359 STATNODE_ULONG(numneg, "Number of negative cache entries"); 360 STATNODE_ULONG(numcache, "Number of cache entries"); 361 STATNODE_COUNTER(numcalls, "Number of cache lookups"); 362 STATNODE_COUNTER(dothits, "Number of '.' hits"); 363 STATNODE_COUNTER(dotdothits, "Number of '..' hits"); 364 STATNODE_COUNTER(numchecks, "Number of checks in lookup"); 365 STATNODE_COUNTER(nummiss, "Number of cache misses"); 366 STATNODE_COUNTER(nummisszap, "Number of cache misses we do not want to cache"); 367 STATNODE_COUNTER(numposzaps, 368 "Number of cache hits (positive) we do not want to cache"); 369 STATNODE_COUNTER(numposhits, "Number of cache hits (positive)"); 370 STATNODE_COUNTER(numnegzaps, 371 "Number of cache hits (negative) we do not want to cache"); 372 STATNODE_COUNTER(numneghits, "Number of cache hits (negative)"); 373 /* These count for kern___getcwd(), too. */ 374 STATNODE_COUNTER(numfullpathcalls, "Number of fullpath search calls"); 375 STATNODE_COUNTER(numfullpathfail1, "Number of fullpath search errors (ENOTDIR)"); 376 STATNODE_COUNTER(numfullpathfail2, 377 "Number of fullpath search errors (VOP_VPTOCNP failures)"); 378 STATNODE_COUNTER(numfullpathfail4, "Number of fullpath search errors (ENOMEM)"); 379 STATNODE_COUNTER(numfullpathfound, "Number of successful fullpath calls"); 380 static long zap_and_exit_bucket_fail; STATNODE_ULONG(zap_and_exit_bucket_fail, 381 "Number of times zap_and_exit failed to lock"); 382 static long cache_lock_vnodes_cel_3_failures; 383 STATNODE_ULONG(cache_lock_vnodes_cel_3_failures, 384 "Number of times 3-way vnode locking failed"); 385 386 static void cache_zap_locked(struct namecache *ncp, bool neg_locked); 387 static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 388 char *buf, char **retbuf, u_int buflen); 389 390 static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); 391 392 static int cache_yield; 393 SYSCTL_INT(_vfs_cache, OID_AUTO, yield, CTLFLAG_RD, &cache_yield, 0, 394 "Number of times cache called yield"); 395 396 static void 397 cache_maybe_yield(void) 398 { 399 400 if (should_yield()) { 401 cache_yield++; 402 kern_yield(PRI_USER); 403 } 404 } 405 406 static inline void 407 cache_assert_vlp_locked(struct mtx *vlp) 408 { 409 410 if (vlp != NULL) 411 mtx_assert(vlp, MA_OWNED); 412 } 413 414 static inline void 415 cache_assert_vnode_locked(struct vnode *vp) 416 { 417 struct mtx *vlp; 418 419 vlp = VP2VNODELOCK(vp); 420 cache_assert_vlp_locked(vlp); 421 } 422 423 static uint32_t 424 cache_get_hash(char *name, u_char len, struct vnode *dvp) 425 { 426 uint32_t hash; 427 428 hash = fnv_32_buf(name, len, FNV1_32_INIT); 429 hash = fnv_32_buf(&dvp, sizeof(dvp), hash); 430 return (hash); 431 } 432 433 static inline struct rwlock * 434 NCP2BUCKETLOCK(struct namecache *ncp) 435 { 436 uint32_t hash; 437 438 hash = cache_get_hash(ncp->nc_name, ncp->nc_nlen, ncp->nc_dvp); 439 return (HASH2BUCKETLOCK(hash)); 440 } 441 442 #ifdef INVARIANTS 443 static void 444 cache_assert_bucket_locked(struct namecache *ncp, int mode) 445 { 446 struct rwlock *blp; 447 448 blp = NCP2BUCKETLOCK(ncp); 449 rw_assert(blp, mode); 450 } 451 #else 452 #define cache_assert_bucket_locked(x, y) do { } while (0) 453 #endif 454 455 #define cache_sort(x, y) _cache_sort((void **)(x), (void **)(y)) 456 static void 457 _cache_sort(void **p1, void **p2) 458 { 459 void *tmp; 460 461 if (*p1 > *p2) { 462 tmp = *p2; 463 *p2 = *p1; 464 *p1 = tmp; 465 } 466 } 467 468 static void 469 cache_lock_all_buckets(void) 470 { 471 u_int i; 472 473 for (i = 0; i < numbucketlocks; i++) 474 rw_wlock(&bucketlocks[i]); 475 } 476 477 static void 478 cache_unlock_all_buckets(void) 479 { 480 u_int i; 481 482 for (i = 0; i < numbucketlocks; i++) 483 rw_wunlock(&bucketlocks[i]); 484 } 485 486 static void 487 cache_lock_all_vnodes(void) 488 { 489 u_int i; 490 491 for (i = 0; i < numvnodelocks; i++) 492 mtx_lock(&vnodelocks[i]); 493 } 494 495 static void 496 cache_unlock_all_vnodes(void) 497 { 498 u_int i; 499 500 for (i = 0; i < numvnodelocks; i++) 501 mtx_unlock(&vnodelocks[i]); 502 } 503 504 static int 505 cache_trylock_vnodes(struct mtx *vlp1, struct mtx *vlp2) 506 { 507 508 cache_sort(&vlp1, &vlp2); 509 MPASS(vlp2 != NULL); 510 511 if (vlp1 != NULL) { 512 if (!mtx_trylock(vlp1)) 513 return (EAGAIN); 514 } 515 if (!mtx_trylock(vlp2)) { 516 if (vlp1 != NULL) 517 mtx_unlock(vlp1); 518 return (EAGAIN); 519 } 520 521 return (0); 522 } 523 524 static void 525 cache_unlock_vnodes(struct mtx *vlp1, struct mtx *vlp2) 526 { 527 528 MPASS(vlp1 != NULL || vlp2 != NULL); 529 530 if (vlp1 != NULL) 531 mtx_unlock(vlp1); 532 if (vlp2 != NULL) 533 mtx_unlock(vlp2); 534 } 535 536 static int 537 sysctl_nchstats(SYSCTL_HANDLER_ARGS) 538 { 539 struct nchstats snap; 540 541 if (req->oldptr == NULL) 542 return (SYSCTL_OUT(req, 0, sizeof(snap))); 543 544 snap = nchstats; 545 snap.ncs_goodhits = counter_u64_fetch(numposhits); 546 snap.ncs_neghits = counter_u64_fetch(numneghits); 547 snap.ncs_badhits = counter_u64_fetch(numposzaps) + 548 counter_u64_fetch(numnegzaps); 549 snap.ncs_miss = counter_u64_fetch(nummisszap) + 550 counter_u64_fetch(nummiss); 551 552 return (SYSCTL_OUT(req, &snap, sizeof(snap))); 553 } 554 SYSCTL_PROC(_vfs_cache, OID_AUTO, nchstats, CTLTYPE_OPAQUE | CTLFLAG_RD | 555 CTLFLAG_MPSAFE, 0, 0, sysctl_nchstats, "LU", 556 "VFS cache effectiveness statistics"); 557 558 #ifdef DIAGNOSTIC 559 /* 560 * Grab an atomic snapshot of the name cache hash chain lengths 561 */ 562 static SYSCTL_NODE(_debug, OID_AUTO, hashstat, CTLFLAG_RW, NULL, 563 "hash table stats"); 564 565 static int 566 sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS) 567 { 568 struct nchashhead *ncpp; 569 struct namecache *ncp; 570 int i, error, n_nchash, *cntbuf; 571 572 retry: 573 n_nchash = nchash + 1; /* nchash is max index, not count */ 574 if (req->oldptr == NULL) 575 return SYSCTL_OUT(req, 0, n_nchash * sizeof(int)); 576 cntbuf = malloc(n_nchash * sizeof(int), M_TEMP, M_ZERO | M_WAITOK); 577 cache_lock_all_buckets(); 578 if (n_nchash != nchash + 1) { 579 cache_unlock_all_buckets(); 580 free(cntbuf, M_TEMP); 581 goto retry; 582 } 583 /* Scan hash tables counting entries */ 584 for (ncpp = nchashtbl, i = 0; i < n_nchash; ncpp++, i++) 585 LIST_FOREACH(ncp, ncpp, nc_hash) 586 cntbuf[i]++; 587 cache_unlock_all_buckets(); 588 for (error = 0, i = 0; i < n_nchash; i++) 589 if ((error = SYSCTL_OUT(req, &cntbuf[i], sizeof(int))) != 0) 590 break; 591 free(cntbuf, M_TEMP); 592 return (error); 593 } 594 SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD| 595 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_rawnchash, "S,int", 596 "nchash chain lengths"); 597 598 static int 599 sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS) 600 { 601 int error; 602 struct nchashhead *ncpp; 603 struct namecache *ncp; 604 int n_nchash; 605 int count, maxlength, used, pct; 606 607 if (!req->oldptr) 608 return SYSCTL_OUT(req, 0, 4 * sizeof(int)); 609 610 cache_lock_all_buckets(); 611 n_nchash = nchash + 1; /* nchash is max index, not count */ 612 used = 0; 613 maxlength = 0; 614 615 /* Scan hash tables for applicable entries */ 616 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { 617 count = 0; 618 LIST_FOREACH(ncp, ncpp, nc_hash) { 619 count++; 620 } 621 if (count) 622 used++; 623 if (maxlength < count) 624 maxlength = count; 625 } 626 n_nchash = nchash + 1; 627 cache_unlock_all_buckets(); 628 pct = (used * 100) / (n_nchash / 100); 629 error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash)); 630 if (error) 631 return (error); 632 error = SYSCTL_OUT(req, &used, sizeof(used)); 633 if (error) 634 return (error); 635 error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength)); 636 if (error) 637 return (error); 638 error = SYSCTL_OUT(req, &pct, sizeof(pct)); 639 if (error) 640 return (error); 641 return (0); 642 } 643 SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD| 644 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_nchash, "I", 645 "nchash statistics (number of total/used buckets, maximum chain length, usage percentage)"); 646 #endif 647 648 /* 649 * Negative entries management 650 * 651 * A variation of LRU scheme is used. New entries are hashed into one of 652 * numneglists cold lists. Entries get promoted to the hot list on first hit. 653 * Partial LRU for the hot list is maintained by requeueing them every 654 * ncneghitsrequeue hits. 655 * 656 * The shrinker will demote hot list head and evict from the cold list in a 657 * round-robin manner. 658 */ 659 static void 660 cache_negative_hit(struct namecache *ncp) 661 { 662 struct neglist *neglist; 663 u_int hits; 664 665 MPASS(ncp->nc_flag & NCF_NEGATIVE); 666 hits = atomic_fetchadd_int(&ncp->nc_neghits, 1); 667 if (ncp->nc_flag & NCF_HOTNEGATIVE) { 668 if ((hits % ncneghitsrequeue) != 0) 669 return; 670 mtx_lock(&ncneg_hot.nl_lock); 671 if (ncp->nc_flag & NCF_HOTNEGATIVE) { 672 TAILQ_REMOVE(&ncneg_hot.nl_list, ncp, nc_dst); 673 TAILQ_INSERT_TAIL(&ncneg_hot.nl_list, ncp, nc_dst); 674 mtx_unlock(&ncneg_hot.nl_lock); 675 return; 676 } 677 /* 678 * The shrinker cleared the flag and removed the entry from 679 * the hot list. Put it back. 680 */ 681 } else { 682 mtx_lock(&ncneg_hot.nl_lock); 683 } 684 neglist = NCP2NEGLIST(ncp); 685 mtx_lock(&neglist->nl_lock); 686 if (!(ncp->nc_flag & NCF_HOTNEGATIVE)) { 687 TAILQ_REMOVE(&neglist->nl_list, ncp, nc_dst); 688 TAILQ_INSERT_TAIL(&ncneg_hot.nl_list, ncp, nc_dst); 689 ncp->nc_flag |= NCF_HOTNEGATIVE; 690 } 691 mtx_unlock(&neglist->nl_lock); 692 mtx_unlock(&ncneg_hot.nl_lock); 693 } 694 695 static void 696 cache_negative_insert(struct namecache *ncp, bool neg_locked) 697 { 698 struct neglist *neglist; 699 700 MPASS(ncp->nc_flag & NCF_NEGATIVE); 701 cache_assert_bucket_locked(ncp, RA_WLOCKED); 702 neglist = NCP2NEGLIST(ncp); 703 if (!neg_locked) { 704 mtx_lock(&neglist->nl_lock); 705 } else { 706 mtx_assert(&neglist->nl_lock, MA_OWNED); 707 } 708 TAILQ_INSERT_TAIL(&neglist->nl_list, ncp, nc_dst); 709 if (!neg_locked) 710 mtx_unlock(&neglist->nl_lock); 711 atomic_add_rel_long(&numneg, 1); 712 } 713 714 static void 715 cache_negative_remove(struct namecache *ncp, bool neg_locked) 716 { 717 struct neglist *neglist; 718 bool hot_locked = false; 719 bool list_locked = false; 720 721 MPASS(ncp->nc_flag & NCF_NEGATIVE); 722 cache_assert_bucket_locked(ncp, RA_WLOCKED); 723 neglist = NCP2NEGLIST(ncp); 724 if (!neg_locked) { 725 if (ncp->nc_flag & NCF_HOTNEGATIVE) { 726 hot_locked = true; 727 mtx_lock(&ncneg_hot.nl_lock); 728 if (!(ncp->nc_flag & NCF_HOTNEGATIVE)) { 729 list_locked = true; 730 mtx_lock(&neglist->nl_lock); 731 } 732 } else { 733 list_locked = true; 734 mtx_lock(&neglist->nl_lock); 735 } 736 } 737 if (ncp->nc_flag & NCF_HOTNEGATIVE) { 738 mtx_assert(&ncneg_hot.nl_lock, MA_OWNED); 739 TAILQ_REMOVE(&ncneg_hot.nl_list, ncp, nc_dst); 740 } else { 741 mtx_assert(&neglist->nl_lock, MA_OWNED); 742 TAILQ_REMOVE(&neglist->nl_list, ncp, nc_dst); 743 } 744 if (list_locked) 745 mtx_unlock(&neglist->nl_lock); 746 if (hot_locked) 747 mtx_unlock(&ncneg_hot.nl_lock); 748 atomic_subtract_rel_long(&numneg, 1); 749 } 750 751 static void 752 cache_negative_shrink_select(int start, struct namecache **ncpp, 753 struct neglist **neglistpp) 754 { 755 struct neglist *neglist; 756 struct namecache *ncp; 757 int i; 758 759 *ncpp = ncp = NULL; 760 neglist = NULL; 761 762 for (i = start; i < numneglists; i++) { 763 neglist = &neglists[i]; 764 if (TAILQ_FIRST(&neglist->nl_list) == NULL) 765 continue; 766 mtx_lock(&neglist->nl_lock); 767 ncp = TAILQ_FIRST(&neglist->nl_list); 768 if (ncp != NULL) 769 break; 770 mtx_unlock(&neglist->nl_lock); 771 } 772 773 *neglistpp = neglist; 774 *ncpp = ncp; 775 } 776 777 static void 778 cache_negative_zap_one(void) 779 { 780 struct namecache *ncp, *ncp2; 781 struct neglist *neglist; 782 struct mtx *dvlp; 783 struct rwlock *blp; 784 785 if (!mtx_trylock(&ncneg_shrink_lock)) 786 return; 787 788 mtx_lock(&ncneg_hot.nl_lock); 789 ncp = TAILQ_FIRST(&ncneg_hot.nl_list); 790 if (ncp != NULL) { 791 neglist = NCP2NEGLIST(ncp); 792 mtx_lock(&neglist->nl_lock); 793 TAILQ_REMOVE(&ncneg_hot.nl_list, ncp, nc_dst); 794 TAILQ_INSERT_TAIL(&neglist->nl_list, ncp, nc_dst); 795 ncp->nc_flag &= ~NCF_HOTNEGATIVE; 796 mtx_unlock(&neglist->nl_lock); 797 } 798 799 cache_negative_shrink_select(shrink_list_turn, &ncp, &neglist); 800 shrink_list_turn++; 801 if (shrink_list_turn == numneglists) 802 shrink_list_turn = 0; 803 if (ncp == NULL && shrink_list_turn == 0) 804 cache_negative_shrink_select(shrink_list_turn, &ncp, &neglist); 805 if (ncp == NULL) { 806 mtx_unlock(&ncneg_hot.nl_lock); 807 goto out; 808 } 809 810 MPASS(ncp->nc_flag & NCF_NEGATIVE); 811 dvlp = VP2VNODELOCK(ncp->nc_dvp); 812 blp = NCP2BUCKETLOCK(ncp); 813 mtx_unlock(&neglist->nl_lock); 814 mtx_unlock(&ncneg_hot.nl_lock); 815 mtx_lock(dvlp); 816 rw_wlock(blp); 817 mtx_lock(&neglist->nl_lock); 818 ncp2 = TAILQ_FIRST(&neglist->nl_list); 819 if (ncp != ncp2 || dvlp != VP2VNODELOCK(ncp2->nc_dvp) || 820 blp != NCP2BUCKETLOCK(ncp2) || !(ncp2->nc_flag & NCF_NEGATIVE)) { 821 ncp = NULL; 822 goto out_unlock_all; 823 } 824 SDT_PROBE3(vfs, namecache, shrink_negative, done, ncp->nc_dvp, 825 ncp->nc_name, ncp->nc_neghits); 826 827 cache_zap_locked(ncp, true); 828 out_unlock_all: 829 mtx_unlock(&neglist->nl_lock); 830 rw_wunlock(blp); 831 mtx_unlock(dvlp); 832 out: 833 mtx_unlock(&ncneg_shrink_lock); 834 cache_free(ncp); 835 } 836 837 /* 838 * cache_zap_locked(): 839 * 840 * Removes a namecache entry from cache, whether it contains an actual 841 * pointer to a vnode or if it is just a negative cache entry. 842 */ 843 static void 844 cache_zap_locked(struct namecache *ncp, bool neg_locked) 845 { 846 847 if (!(ncp->nc_flag & NCF_NEGATIVE)) 848 cache_assert_vnode_locked(ncp->nc_vp); 849 cache_assert_vnode_locked(ncp->nc_dvp); 850 cache_assert_bucket_locked(ncp, RA_WLOCKED); 851 852 CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp, 853 (ncp->nc_flag & NCF_NEGATIVE) ? NULL : ncp->nc_vp); 854 LIST_REMOVE(ncp, nc_hash); 855 if (!(ncp->nc_flag & NCF_NEGATIVE)) { 856 SDT_PROBE3(vfs, namecache, zap, done, ncp->nc_dvp, 857 ncp->nc_name, ncp->nc_vp); 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 SDT_PROBE3(vfs, namecache, zap_negative, done, ncp->nc_dvp, 863 ncp->nc_name, ncp->nc_neghits); 864 cache_negative_remove(ncp, neg_locked); 865 } 866 if (ncp->nc_flag & NCF_ISDOTDOT) { 867 if (ncp == ncp->nc_dvp->v_cache_dd) 868 ncp->nc_dvp->v_cache_dd = NULL; 869 } else { 870 LIST_REMOVE(ncp, nc_src); 871 if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) { 872 ncp->nc_flag |= NCF_DVDROP; 873 atomic_subtract_rel_long(&numcachehv, 1); 874 } 875 } 876 atomic_subtract_rel_long(&numcache, 1); 877 } 878 879 static void 880 cache_zap_negative_locked_vnode_kl(struct namecache *ncp, struct vnode *vp) 881 { 882 struct rwlock *blp; 883 884 MPASS(ncp->nc_dvp == vp); 885 MPASS(ncp->nc_flag & NCF_NEGATIVE); 886 cache_assert_vnode_locked(vp); 887 888 blp = NCP2BUCKETLOCK(ncp); 889 rw_wlock(blp); 890 cache_zap_locked(ncp, false); 891 rw_wunlock(blp); 892 } 893 894 static bool 895 cache_zap_locked_vnode_kl2(struct namecache *ncp, struct vnode *vp, 896 struct mtx **vlpp) 897 { 898 struct mtx *pvlp, *vlp1, *vlp2, *to_unlock; 899 struct rwlock *blp; 900 901 MPASS(vp == ncp->nc_dvp || vp == ncp->nc_vp); 902 cache_assert_vnode_locked(vp); 903 904 if (ncp->nc_flag & NCF_NEGATIVE) { 905 if (*vlpp != NULL) { 906 mtx_unlock(*vlpp); 907 *vlpp = NULL; 908 } 909 cache_zap_negative_locked_vnode_kl(ncp, vp); 910 return (true); 911 } 912 913 pvlp = VP2VNODELOCK(vp); 914 blp = NCP2BUCKETLOCK(ncp); 915 vlp1 = VP2VNODELOCK(ncp->nc_dvp); 916 vlp2 = VP2VNODELOCK(ncp->nc_vp); 917 918 if (*vlpp == vlp1 || *vlpp == vlp2) { 919 to_unlock = *vlpp; 920 *vlpp = NULL; 921 } else { 922 if (*vlpp != NULL) { 923 mtx_unlock(*vlpp); 924 *vlpp = NULL; 925 } 926 cache_sort(&vlp1, &vlp2); 927 if (vlp1 == pvlp) { 928 mtx_lock(vlp2); 929 to_unlock = vlp2; 930 } else { 931 if (!mtx_trylock(vlp1)) 932 goto out_relock; 933 to_unlock = vlp1; 934 } 935 } 936 rw_wlock(blp); 937 cache_zap_locked(ncp, false); 938 rw_wunlock(blp); 939 if (to_unlock != NULL) 940 mtx_unlock(to_unlock); 941 return (true); 942 943 out_relock: 944 mtx_unlock(vlp2); 945 mtx_lock(vlp1); 946 mtx_lock(vlp2); 947 MPASS(*vlpp == NULL); 948 *vlpp = vlp1; 949 return (false); 950 } 951 952 static int 953 cache_zap_locked_vnode(struct namecache *ncp, struct vnode *vp) 954 { 955 struct mtx *pvlp, *vlp1, *vlp2, *to_unlock; 956 struct rwlock *blp; 957 int error = 0; 958 959 MPASS(vp == ncp->nc_dvp || vp == ncp->nc_vp); 960 cache_assert_vnode_locked(vp); 961 962 pvlp = VP2VNODELOCK(vp); 963 if (ncp->nc_flag & NCF_NEGATIVE) { 964 cache_zap_negative_locked_vnode_kl(ncp, vp); 965 goto out; 966 } 967 968 blp = NCP2BUCKETLOCK(ncp); 969 vlp1 = VP2VNODELOCK(ncp->nc_dvp); 970 vlp2 = VP2VNODELOCK(ncp->nc_vp); 971 cache_sort(&vlp1, &vlp2); 972 if (vlp1 == pvlp) { 973 mtx_lock(vlp2); 974 to_unlock = vlp2; 975 } else { 976 if (!mtx_trylock(vlp1)) { 977 error = EAGAIN; 978 goto out; 979 } 980 to_unlock = vlp1; 981 } 982 rw_wlock(blp); 983 cache_zap_locked(ncp, false); 984 rw_wunlock(blp); 985 mtx_unlock(to_unlock); 986 out: 987 mtx_unlock(pvlp); 988 return (error); 989 } 990 991 static int 992 cache_zap_wlocked_bucket(struct namecache *ncp, struct rwlock *blp) 993 { 994 struct mtx *dvlp, *vlp; 995 996 cache_assert_bucket_locked(ncp, RA_WLOCKED); 997 998 dvlp = VP2VNODELOCK(ncp->nc_dvp); 999 vlp = NULL; 1000 if (!(ncp->nc_flag & NCF_NEGATIVE)) 1001 vlp = VP2VNODELOCK(ncp->nc_vp); 1002 if (cache_trylock_vnodes(dvlp, vlp) == 0) { 1003 cache_zap_locked(ncp, false); 1004 rw_wunlock(blp); 1005 cache_unlock_vnodes(dvlp, vlp); 1006 return (0); 1007 } 1008 1009 rw_wunlock(blp); 1010 return (EAGAIN); 1011 } 1012 1013 static int 1014 cache_zap_rlocked_bucket(struct namecache *ncp, struct rwlock *blp) 1015 { 1016 struct mtx *dvlp, *vlp; 1017 1018 cache_assert_bucket_locked(ncp, RA_RLOCKED); 1019 1020 dvlp = VP2VNODELOCK(ncp->nc_dvp); 1021 vlp = NULL; 1022 if (!(ncp->nc_flag & NCF_NEGATIVE)) 1023 vlp = VP2VNODELOCK(ncp->nc_vp); 1024 if (cache_trylock_vnodes(dvlp, vlp) == 0) { 1025 rw_runlock(blp); 1026 rw_wlock(blp); 1027 cache_zap_locked(ncp, false); 1028 rw_wunlock(blp); 1029 cache_unlock_vnodes(dvlp, vlp); 1030 return (0); 1031 } 1032 1033 rw_runlock(blp); 1034 return (EAGAIN); 1035 } 1036 1037 static int 1038 cache_zap_wlocked_bucket_kl(struct namecache *ncp, struct rwlock *blp, 1039 struct mtx **vlpp1, struct mtx **vlpp2) 1040 { 1041 struct mtx *dvlp, *vlp; 1042 1043 cache_assert_bucket_locked(ncp, RA_WLOCKED); 1044 1045 dvlp = VP2VNODELOCK(ncp->nc_dvp); 1046 vlp = NULL; 1047 if (!(ncp->nc_flag & NCF_NEGATIVE)) 1048 vlp = VP2VNODELOCK(ncp->nc_vp); 1049 cache_sort(&dvlp, &vlp); 1050 1051 if (*vlpp1 == dvlp && *vlpp2 == vlp) { 1052 cache_zap_locked(ncp, false); 1053 cache_unlock_vnodes(dvlp, vlp); 1054 *vlpp1 = NULL; 1055 *vlpp2 = NULL; 1056 return (0); 1057 } 1058 1059 if (*vlpp1 != NULL) 1060 mtx_unlock(*vlpp1); 1061 if (*vlpp2 != NULL) 1062 mtx_unlock(*vlpp2); 1063 *vlpp1 = NULL; 1064 *vlpp2 = NULL; 1065 1066 if (cache_trylock_vnodes(dvlp, vlp) == 0) { 1067 cache_zap_locked(ncp, false); 1068 cache_unlock_vnodes(dvlp, vlp); 1069 return (0); 1070 } 1071 1072 rw_wunlock(blp); 1073 *vlpp1 = dvlp; 1074 *vlpp2 = vlp; 1075 if (*vlpp1 != NULL) 1076 mtx_lock(*vlpp1); 1077 mtx_lock(*vlpp2); 1078 rw_wlock(blp); 1079 return (EAGAIN); 1080 } 1081 1082 static void 1083 cache_lookup_unlock(struct rwlock *blp, struct mtx *vlp) 1084 { 1085 1086 if (blp != NULL) { 1087 rw_runlock(blp); 1088 } else { 1089 mtx_unlock(vlp); 1090 } 1091 } 1092 1093 static int __noinline 1094 cache_lookup_dot(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, 1095 struct timespec *tsp, int *ticksp) 1096 { 1097 int ltype; 1098 1099 *vpp = dvp; 1100 CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .", 1101 dvp, cnp->cn_nameptr); 1102 counter_u64_add(dothits, 1); 1103 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ".", *vpp); 1104 if (tsp != NULL) 1105 timespecclear(tsp); 1106 if (ticksp != NULL) 1107 *ticksp = ticks; 1108 vrefact(*vpp); 1109 /* 1110 * When we lookup "." we still can be asked to lock it 1111 * differently... 1112 */ 1113 ltype = cnp->cn_lkflags & LK_TYPE_MASK; 1114 if (ltype != VOP_ISLOCKED(*vpp)) { 1115 if (ltype == LK_EXCLUSIVE) { 1116 vn_lock(*vpp, LK_UPGRADE | LK_RETRY); 1117 if ((*vpp)->v_iflag & VI_DOOMED) { 1118 /* forced unmount */ 1119 vrele(*vpp); 1120 *vpp = NULL; 1121 return (ENOENT); 1122 } 1123 } else 1124 vn_lock(*vpp, LK_DOWNGRADE | LK_RETRY); 1125 } 1126 return (-1); 1127 } 1128 1129 static __noinline int 1130 cache_lookup_nomakeentry(struct vnode *dvp, struct vnode **vpp, 1131 struct componentname *cnp, struct timespec *tsp, int *ticksp) 1132 { 1133 struct namecache *ncp; 1134 struct rwlock *blp; 1135 struct mtx *dvlp, *dvlp2; 1136 uint32_t hash; 1137 int error; 1138 1139 if (cnp->cn_namelen == 2 && 1140 cnp->cn_nameptr[0] == '.' && cnp->cn_nameptr[1] == '.') { 1141 counter_u64_add(dotdothits, 1); 1142 dvlp = VP2VNODELOCK(dvp); 1143 dvlp2 = NULL; 1144 mtx_lock(dvlp); 1145 retry_dotdot: 1146 ncp = dvp->v_cache_dd; 1147 if (ncp == NULL) { 1148 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, 1149 "..", NULL); 1150 mtx_unlock(dvlp); 1151 if (dvlp2 != NULL) 1152 mtx_unlock(dvlp2); 1153 return (0); 1154 } 1155 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) { 1156 if (ncp->nc_dvp != dvp) 1157 panic("dvp %p v_cache_dd %p\n", dvp, ncp); 1158 if (!cache_zap_locked_vnode_kl2(ncp, 1159 dvp, &dvlp2)) 1160 goto retry_dotdot; 1161 MPASS(dvp->v_cache_dd == NULL); 1162 mtx_unlock(dvlp); 1163 if (dvlp2 != NULL) 1164 mtx_unlock(dvlp2); 1165 cache_free(ncp); 1166 } else { 1167 dvp->v_cache_dd = NULL; 1168 mtx_unlock(dvlp); 1169 if (dvlp2 != NULL) 1170 mtx_unlock(dvlp2); 1171 } 1172 return (0); 1173 } 1174 1175 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp); 1176 blp = HASH2BUCKETLOCK(hash); 1177 retry: 1178 if (LIST_EMPTY(NCHHASH(hash))) 1179 goto out_no_entry; 1180 1181 rw_wlock(blp); 1182 1183 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 1184 counter_u64_add(numchecks, 1); 1185 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 1186 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 1187 break; 1188 } 1189 1190 /* We failed to find an entry */ 1191 if (ncp == NULL) { 1192 rw_wunlock(blp); 1193 goto out_no_entry; 1194 } 1195 1196 counter_u64_add(numposzaps, 1); 1197 1198 error = cache_zap_wlocked_bucket(ncp, blp); 1199 if (error != 0) { 1200 zap_and_exit_bucket_fail++; 1201 cache_maybe_yield(); 1202 goto retry; 1203 } 1204 cache_free(ncp); 1205 return (0); 1206 out_no_entry: 1207 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr, NULL); 1208 counter_u64_add(nummisszap, 1); 1209 return (0); 1210 } 1211 1212 /** 1213 * Lookup a name in the name cache 1214 * 1215 * # Arguments 1216 * 1217 * - dvp: Parent directory in which to search. 1218 * - vpp: Return argument. Will contain desired vnode on cache hit. 1219 * - cnp: Parameters of the name search. The most interesting bits of 1220 * the cn_flags field have the following meanings: 1221 * - MAKEENTRY: If clear, free an entry from the cache rather than look 1222 * it up. 1223 * - ISDOTDOT: Must be set if and only if cn_nameptr == ".." 1224 * - tsp: Return storage for cache timestamp. On a successful (positive 1225 * or negative) lookup, tsp will be filled with any timespec that 1226 * was stored when this cache entry was created. However, it will 1227 * be clear for "." entries. 1228 * - ticks: Return storage for alternate cache timestamp. On a successful 1229 * (positive or negative) lookup, it will contain the ticks value 1230 * that was current when the cache entry was created, unless cnp 1231 * was ".". 1232 * 1233 * # Returns 1234 * 1235 * - -1: A positive cache hit. vpp will contain the desired vnode. 1236 * - ENOENT: A negative cache hit, or dvp was recycled out from under us due 1237 * to a forced unmount. vpp will not be modified. If the entry 1238 * is a whiteout, then the ISWHITEOUT flag will be set in 1239 * cnp->cn_flags. 1240 * - 0: A cache miss. vpp will not be modified. 1241 * 1242 * # Locking 1243 * 1244 * On a cache hit, vpp will be returned locked and ref'd. If we're looking up 1245 * .., dvp is unlocked. If we're looking up . an extra ref is taken, but the 1246 * lock is not recursively acquired. 1247 */ 1248 int 1249 cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, 1250 struct timespec *tsp, int *ticksp) 1251 { 1252 struct namecache_ts *ncp_ts; 1253 struct namecache *ncp; 1254 struct rwlock *blp; 1255 struct mtx *dvlp; 1256 uint32_t hash; 1257 int error, ltype; 1258 1259 if (__predict_false(!doingcache)) { 1260 cnp->cn_flags &= ~MAKEENTRY; 1261 return (0); 1262 } 1263 1264 counter_u64_add(numcalls, 1); 1265 1266 if (__predict_false(cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.')) 1267 return (cache_lookup_dot(dvp, vpp, cnp, tsp, ticksp)); 1268 1269 if ((cnp->cn_flags & MAKEENTRY) == 0) 1270 return (cache_lookup_nomakeentry(dvp, vpp, cnp, tsp, ticksp)); 1271 1272 retry: 1273 blp = NULL; 1274 dvlp = NULL; 1275 error = 0; 1276 if (cnp->cn_namelen == 2 && 1277 cnp->cn_nameptr[0] == '.' && cnp->cn_nameptr[1] == '.') { 1278 counter_u64_add(dotdothits, 1); 1279 dvlp = VP2VNODELOCK(dvp); 1280 mtx_lock(dvlp); 1281 ncp = dvp->v_cache_dd; 1282 if (ncp == NULL) { 1283 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, 1284 "..", NULL); 1285 mtx_unlock(dvlp); 1286 return (0); 1287 } 1288 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) { 1289 if (ncp->nc_flag & NCF_NEGATIVE) 1290 *vpp = NULL; 1291 else 1292 *vpp = ncp->nc_vp; 1293 } else 1294 *vpp = ncp->nc_dvp; 1295 /* Return failure if negative entry was found. */ 1296 if (*vpp == NULL) 1297 goto negative_success; 1298 CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..", 1299 dvp, cnp->cn_nameptr, *vpp); 1300 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, "..", 1301 *vpp); 1302 cache_out_ts(ncp, tsp, ticksp); 1303 if ((ncp->nc_flag & (NCF_ISDOTDOT | NCF_DTS)) == 1304 NCF_DTS && tsp != NULL) { 1305 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); 1306 *tsp = ncp_ts->nc_dotdottime; 1307 } 1308 goto success; 1309 } 1310 1311 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp); 1312 blp = HASH2BUCKETLOCK(hash); 1313 rw_rlock(blp); 1314 1315 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 1316 counter_u64_add(numchecks, 1); 1317 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 1318 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 1319 break; 1320 } 1321 1322 /* We failed to find an entry */ 1323 if (ncp == NULL) { 1324 rw_runlock(blp); 1325 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr, 1326 NULL); 1327 counter_u64_add(nummiss, 1); 1328 return (0); 1329 } 1330 1331 /* We found a "positive" match, return the vnode */ 1332 if (!(ncp->nc_flag & NCF_NEGATIVE)) { 1333 counter_u64_add(numposhits, 1); 1334 *vpp = ncp->nc_vp; 1335 CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p", 1336 dvp, cnp->cn_nameptr, *vpp, ncp); 1337 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ncp->nc_name, 1338 *vpp); 1339 cache_out_ts(ncp, tsp, ticksp); 1340 goto success; 1341 } 1342 1343 negative_success: 1344 /* We found a negative match, and want to create it, so purge */ 1345 if (cnp->cn_nameiop == CREATE) { 1346 counter_u64_add(numnegzaps, 1); 1347 goto zap_and_exit; 1348 } 1349 1350 counter_u64_add(numneghits, 1); 1351 cache_negative_hit(ncp); 1352 if (ncp->nc_flag & NCF_WHITE) 1353 cnp->cn_flags |= ISWHITEOUT; 1354 SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp, 1355 ncp->nc_name); 1356 cache_out_ts(ncp, tsp, ticksp); 1357 cache_lookup_unlock(blp, dvlp); 1358 return (ENOENT); 1359 1360 success: 1361 /* 1362 * On success we return a locked and ref'd vnode as per the lookup 1363 * protocol. 1364 */ 1365 MPASS(dvp != *vpp); 1366 ltype = 0; /* silence gcc warning */ 1367 if (cnp->cn_flags & ISDOTDOT) { 1368 ltype = VOP_ISLOCKED(dvp); 1369 VOP_UNLOCK(dvp, 0); 1370 } 1371 vhold(*vpp); 1372 cache_lookup_unlock(blp, dvlp); 1373 error = vget(*vpp, cnp->cn_lkflags | LK_VNHELD, cnp->cn_thread); 1374 if (cnp->cn_flags & ISDOTDOT) { 1375 vn_lock(dvp, ltype | LK_RETRY); 1376 if (dvp->v_iflag & VI_DOOMED) { 1377 if (error == 0) 1378 vput(*vpp); 1379 *vpp = NULL; 1380 return (ENOENT); 1381 } 1382 } 1383 if (error) { 1384 *vpp = NULL; 1385 goto retry; 1386 } 1387 if ((cnp->cn_flags & ISLASTCN) && 1388 (cnp->cn_lkflags & LK_TYPE_MASK) == LK_EXCLUSIVE) { 1389 ASSERT_VOP_ELOCKED(*vpp, "cache_lookup"); 1390 } 1391 return (-1); 1392 1393 zap_and_exit: 1394 if (blp != NULL) 1395 error = cache_zap_rlocked_bucket(ncp, blp); 1396 else 1397 error = cache_zap_locked_vnode(ncp, dvp); 1398 if (error != 0) { 1399 zap_and_exit_bucket_fail++; 1400 cache_maybe_yield(); 1401 goto retry; 1402 } 1403 cache_free(ncp); 1404 return (0); 1405 } 1406 1407 struct celockstate { 1408 struct mtx *vlp[3]; 1409 struct rwlock *blp[2]; 1410 }; 1411 CTASSERT((nitems(((struct celockstate *)0)->vlp) == 3)); 1412 CTASSERT((nitems(((struct celockstate *)0)->blp) == 2)); 1413 1414 static inline void 1415 cache_celockstate_init(struct celockstate *cel) 1416 { 1417 1418 bzero(cel, sizeof(*cel)); 1419 } 1420 1421 static void 1422 cache_lock_vnodes_cel(struct celockstate *cel, struct vnode *vp, 1423 struct vnode *dvp) 1424 { 1425 struct mtx *vlp1, *vlp2; 1426 1427 MPASS(cel->vlp[0] == NULL); 1428 MPASS(cel->vlp[1] == NULL); 1429 MPASS(cel->vlp[2] == NULL); 1430 1431 MPASS(vp != NULL || dvp != NULL); 1432 1433 vlp1 = VP2VNODELOCK(vp); 1434 vlp2 = VP2VNODELOCK(dvp); 1435 cache_sort(&vlp1, &vlp2); 1436 1437 if (vlp1 != NULL) { 1438 mtx_lock(vlp1); 1439 cel->vlp[0] = vlp1; 1440 } 1441 mtx_lock(vlp2); 1442 cel->vlp[1] = vlp2; 1443 } 1444 1445 static void 1446 cache_unlock_vnodes_cel(struct celockstate *cel) 1447 { 1448 1449 MPASS(cel->vlp[0] != NULL || cel->vlp[1] != NULL); 1450 1451 if (cel->vlp[0] != NULL) 1452 mtx_unlock(cel->vlp[0]); 1453 if (cel->vlp[1] != NULL) 1454 mtx_unlock(cel->vlp[1]); 1455 if (cel->vlp[2] != NULL) 1456 mtx_unlock(cel->vlp[2]); 1457 } 1458 1459 static bool 1460 cache_lock_vnodes_cel_3(struct celockstate *cel, struct vnode *vp) 1461 { 1462 struct mtx *vlp; 1463 bool ret; 1464 1465 cache_assert_vlp_locked(cel->vlp[0]); 1466 cache_assert_vlp_locked(cel->vlp[1]); 1467 MPASS(cel->vlp[2] == NULL); 1468 1469 MPASS(vp != NULL); 1470 vlp = VP2VNODELOCK(vp); 1471 1472 ret = true; 1473 if (vlp >= cel->vlp[1]) { 1474 mtx_lock(vlp); 1475 } else { 1476 if (mtx_trylock(vlp)) 1477 goto out; 1478 cache_lock_vnodes_cel_3_failures++; 1479 cache_unlock_vnodes_cel(cel); 1480 if (vlp < cel->vlp[0]) { 1481 mtx_lock(vlp); 1482 mtx_lock(cel->vlp[0]); 1483 mtx_lock(cel->vlp[1]); 1484 } else { 1485 if (cel->vlp[0] != NULL) 1486 mtx_lock(cel->vlp[0]); 1487 mtx_lock(vlp); 1488 mtx_lock(cel->vlp[1]); 1489 } 1490 ret = false; 1491 } 1492 out: 1493 cel->vlp[2] = vlp; 1494 return (ret); 1495 } 1496 1497 static void 1498 cache_lock_buckets_cel(struct celockstate *cel, struct rwlock *blp1, 1499 struct rwlock *blp2) 1500 { 1501 1502 MPASS(cel->blp[0] == NULL); 1503 MPASS(cel->blp[1] == NULL); 1504 1505 cache_sort(&blp1, &blp2); 1506 1507 if (blp1 != NULL) { 1508 rw_wlock(blp1); 1509 cel->blp[0] = blp1; 1510 } 1511 rw_wlock(blp2); 1512 cel->blp[1] = blp2; 1513 } 1514 1515 static void 1516 cache_unlock_buckets_cel(struct celockstate *cel) 1517 { 1518 1519 if (cel->blp[0] != NULL) 1520 rw_wunlock(cel->blp[0]); 1521 rw_wunlock(cel->blp[1]); 1522 } 1523 1524 /* 1525 * Lock part of the cache affected by the insertion. 1526 * 1527 * This means vnodelocks for dvp, vp and the relevant bucketlock. 1528 * However, insertion can result in removal of an old entry. In this 1529 * case we have an additional vnode and bucketlock pair to lock. If the 1530 * entry is negative, ncelock is locked instead of the vnode. 1531 * 1532 * That is, in the worst case we have to lock 3 vnodes and 2 bucketlocks, while 1533 * preserving the locking order (smaller address first). 1534 */ 1535 static void 1536 cache_enter_lock(struct celockstate *cel, struct vnode *dvp, struct vnode *vp, 1537 uint32_t hash) 1538 { 1539 struct namecache *ncp; 1540 struct rwlock *blps[2]; 1541 1542 blps[0] = HASH2BUCKETLOCK(hash); 1543 for (;;) { 1544 blps[1] = NULL; 1545 cache_lock_vnodes_cel(cel, dvp, vp); 1546 if (vp == NULL || vp->v_type != VDIR) 1547 break; 1548 ncp = vp->v_cache_dd; 1549 if (ncp == NULL) 1550 break; 1551 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 1552 break; 1553 MPASS(ncp->nc_dvp == vp); 1554 blps[1] = NCP2BUCKETLOCK(ncp); 1555 if (ncp->nc_flag & NCF_NEGATIVE) 1556 break; 1557 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp)) 1558 break; 1559 /* 1560 * All vnodes got re-locked. Re-validate the state and if 1561 * nothing changed we are done. Otherwise restart. 1562 */ 1563 if (ncp == vp->v_cache_dd && 1564 (ncp->nc_flag & NCF_ISDOTDOT) != 0 && 1565 blps[1] == NCP2BUCKETLOCK(ncp) && 1566 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2]) 1567 break; 1568 cache_unlock_vnodes_cel(cel); 1569 cel->vlp[0] = NULL; 1570 cel->vlp[1] = NULL; 1571 cel->vlp[2] = NULL; 1572 } 1573 cache_lock_buckets_cel(cel, blps[0], blps[1]); 1574 } 1575 1576 static void 1577 cache_enter_lock_dd(struct celockstate *cel, struct vnode *dvp, struct vnode *vp, 1578 uint32_t hash) 1579 { 1580 struct namecache *ncp; 1581 struct rwlock *blps[2]; 1582 1583 blps[0] = HASH2BUCKETLOCK(hash); 1584 for (;;) { 1585 blps[1] = NULL; 1586 cache_lock_vnodes_cel(cel, dvp, vp); 1587 ncp = dvp->v_cache_dd; 1588 if (ncp == NULL) 1589 break; 1590 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 1591 break; 1592 MPASS(ncp->nc_dvp == dvp); 1593 blps[1] = NCP2BUCKETLOCK(ncp); 1594 if (ncp->nc_flag & NCF_NEGATIVE) 1595 break; 1596 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp)) 1597 break; 1598 if (ncp == dvp->v_cache_dd && 1599 (ncp->nc_flag & NCF_ISDOTDOT) != 0 && 1600 blps[1] == NCP2BUCKETLOCK(ncp) && 1601 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2]) 1602 break; 1603 cache_unlock_vnodes_cel(cel); 1604 cel->vlp[0] = NULL; 1605 cel->vlp[1] = NULL; 1606 cel->vlp[2] = NULL; 1607 } 1608 cache_lock_buckets_cel(cel, blps[0], blps[1]); 1609 } 1610 1611 static void 1612 cache_enter_unlock(struct celockstate *cel) 1613 { 1614 1615 cache_unlock_buckets_cel(cel); 1616 cache_unlock_vnodes_cel(cel); 1617 } 1618 1619 /* 1620 * Add an entry to the cache. 1621 */ 1622 void 1623 cache_enter_time(struct vnode *dvp, struct vnode *vp, struct componentname *cnp, 1624 struct timespec *tsp, struct timespec *dtsp) 1625 { 1626 struct celockstate cel; 1627 struct namecache *ncp, *n2, *ndd; 1628 struct namecache_ts *ncp_ts, *n2_ts; 1629 struct nchashhead *ncpp; 1630 struct neglist *neglist; 1631 uint32_t hash; 1632 int flag; 1633 int len; 1634 bool neg_locked; 1635 u_long lnumcache; 1636 1637 CTR3(KTR_VFS, "cache_enter(%p, %p, %s)", dvp, vp, cnp->cn_nameptr); 1638 VNASSERT(vp == NULL || (vp->v_iflag & VI_DOOMED) == 0, vp, 1639 ("cache_enter: Adding a doomed vnode")); 1640 VNASSERT(dvp == NULL || (dvp->v_iflag & VI_DOOMED) == 0, dvp, 1641 ("cache_enter: Doomed vnode used as src")); 1642 1643 if (__predict_false(!doingcache)) 1644 return; 1645 1646 /* 1647 * Avoid blowout in namecache entries. 1648 */ 1649 lnumcache = atomic_fetchadd_long(&numcache, 1) + 1; 1650 if (__predict_false(lnumcache >= desiredvnodes * ncsizefactor)) { 1651 atomic_add_long(&numcache, -1); 1652 return; 1653 } 1654 1655 cache_celockstate_init(&cel); 1656 ndd = NULL; 1657 ncp_ts = NULL; 1658 flag = 0; 1659 if (cnp->cn_nameptr[0] == '.') { 1660 if (cnp->cn_namelen == 1) 1661 return; 1662 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 1663 len = cnp->cn_namelen; 1664 hash = cache_get_hash(cnp->cn_nameptr, len, dvp); 1665 cache_enter_lock_dd(&cel, dvp, vp, hash); 1666 /* 1667 * If dotdot entry already exists, just retarget it 1668 * to new parent vnode, otherwise continue with new 1669 * namecache entry allocation. 1670 */ 1671 if ((ncp = dvp->v_cache_dd) != NULL && 1672 ncp->nc_flag & NCF_ISDOTDOT) { 1673 KASSERT(ncp->nc_dvp == dvp, 1674 ("wrong isdotdot parent")); 1675 neg_locked = false; 1676 if (ncp->nc_flag & NCF_NEGATIVE || vp == NULL) { 1677 neglist = NCP2NEGLIST(ncp); 1678 mtx_lock(&ncneg_hot.nl_lock); 1679 mtx_lock(&neglist->nl_lock); 1680 neg_locked = true; 1681 } 1682 if (!(ncp->nc_flag & NCF_NEGATIVE)) { 1683 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, 1684 ncp, nc_dst); 1685 } else { 1686 cache_negative_remove(ncp, true); 1687 } 1688 if (vp != NULL) { 1689 TAILQ_INSERT_HEAD(&vp->v_cache_dst, 1690 ncp, nc_dst); 1691 ncp->nc_flag &= ~(NCF_NEGATIVE|NCF_HOTNEGATIVE); 1692 } else { 1693 ncp->nc_flag &= ~(NCF_HOTNEGATIVE); 1694 ncp->nc_flag |= NCF_NEGATIVE; 1695 cache_negative_insert(ncp, true); 1696 } 1697 if (neg_locked) { 1698 mtx_unlock(&neglist->nl_lock); 1699 mtx_unlock(&ncneg_hot.nl_lock); 1700 } 1701 ncp->nc_vp = vp; 1702 cache_enter_unlock(&cel); 1703 return; 1704 } 1705 dvp->v_cache_dd = NULL; 1706 cache_enter_unlock(&cel); 1707 cache_celockstate_init(&cel); 1708 SDT_PROBE3(vfs, namecache, enter, done, dvp, "..", vp); 1709 flag = NCF_ISDOTDOT; 1710 } 1711 } 1712 1713 /* 1714 * Calculate the hash key and setup as much of the new 1715 * namecache entry as possible before acquiring the lock. 1716 */ 1717 ncp = cache_alloc(cnp->cn_namelen, tsp != NULL); 1718 ncp->nc_flag = flag; 1719 ncp->nc_vp = vp; 1720 if (vp == NULL) 1721 ncp->nc_flag |= NCF_NEGATIVE; 1722 ncp->nc_dvp = dvp; 1723 if (tsp != NULL) { 1724 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); 1725 ncp_ts->nc_time = *tsp; 1726 ncp_ts->nc_ticks = ticks; 1727 ncp_ts->nc_nc.nc_flag |= NCF_TS; 1728 if (dtsp != NULL) { 1729 ncp_ts->nc_dotdottime = *dtsp; 1730 ncp_ts->nc_nc.nc_flag |= NCF_DTS; 1731 } 1732 } 1733 len = ncp->nc_nlen = cnp->cn_namelen; 1734 hash = cache_get_hash(cnp->cn_nameptr, len, dvp); 1735 strlcpy(ncp->nc_name, cnp->cn_nameptr, len + 1); 1736 cache_enter_lock(&cel, dvp, vp, hash); 1737 1738 /* 1739 * See if this vnode or negative entry is already in the cache 1740 * with this name. This can happen with concurrent lookups of 1741 * the same path name. 1742 */ 1743 ncpp = NCHHASH(hash); 1744 LIST_FOREACH(n2, ncpp, nc_hash) { 1745 if (n2->nc_dvp == dvp && 1746 n2->nc_nlen == cnp->cn_namelen && 1747 !bcmp(n2->nc_name, cnp->cn_nameptr, n2->nc_nlen)) { 1748 if (tsp != NULL) { 1749 KASSERT((n2->nc_flag & NCF_TS) != 0, 1750 ("no NCF_TS")); 1751 n2_ts = __containerof(n2, struct namecache_ts, nc_nc); 1752 n2_ts->nc_time = ncp_ts->nc_time; 1753 n2_ts->nc_ticks = ncp_ts->nc_ticks; 1754 if (dtsp != NULL) { 1755 n2_ts->nc_dotdottime = ncp_ts->nc_dotdottime; 1756 if (ncp->nc_flag & NCF_NEGATIVE) 1757 mtx_lock(&ncneg_hot.nl_lock); 1758 n2_ts->nc_nc.nc_flag |= NCF_DTS; 1759 if (ncp->nc_flag & NCF_NEGATIVE) 1760 mtx_unlock(&ncneg_hot.nl_lock); 1761 } 1762 } 1763 goto out_unlock_free; 1764 } 1765 } 1766 1767 if (flag == NCF_ISDOTDOT) { 1768 /* 1769 * See if we are trying to add .. entry, but some other lookup 1770 * has populated v_cache_dd pointer already. 1771 */ 1772 if (dvp->v_cache_dd != NULL) 1773 goto out_unlock_free; 1774 KASSERT(vp == NULL || vp->v_type == VDIR, 1775 ("wrong vnode type %p", vp)); 1776 dvp->v_cache_dd = ncp; 1777 } 1778 1779 if (vp != NULL) { 1780 if (vp->v_type == VDIR) { 1781 if (flag != NCF_ISDOTDOT) { 1782 /* 1783 * For this case, the cache entry maps both the 1784 * directory name in it and the name ".." for the 1785 * directory's parent. 1786 */ 1787 if ((ndd = vp->v_cache_dd) != NULL) { 1788 if ((ndd->nc_flag & NCF_ISDOTDOT) != 0) 1789 cache_zap_locked(ndd, false); 1790 else 1791 ndd = NULL; 1792 } 1793 vp->v_cache_dd = ncp; 1794 } 1795 } else { 1796 vp->v_cache_dd = NULL; 1797 } 1798 } 1799 1800 if (flag != NCF_ISDOTDOT) { 1801 if (LIST_EMPTY(&dvp->v_cache_src)) { 1802 vhold(dvp); 1803 atomic_add_rel_long(&numcachehv, 1); 1804 } 1805 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); 1806 } 1807 1808 /* 1809 * Insert the new namecache entry into the appropriate chain 1810 * within the cache entries table. 1811 */ 1812 LIST_INSERT_HEAD(ncpp, ncp, nc_hash); 1813 1814 /* 1815 * If the entry is "negative", we place it into the 1816 * "negative" cache queue, otherwise, we place it into the 1817 * destination vnode's cache entries queue. 1818 */ 1819 if (vp != NULL) { 1820 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); 1821 SDT_PROBE3(vfs, namecache, enter, done, dvp, ncp->nc_name, 1822 vp); 1823 } else { 1824 if (cnp->cn_flags & ISWHITEOUT) 1825 ncp->nc_flag |= NCF_WHITE; 1826 cache_negative_insert(ncp, false); 1827 SDT_PROBE2(vfs, namecache, enter_negative, done, dvp, 1828 ncp->nc_name); 1829 } 1830 cache_enter_unlock(&cel); 1831 if (numneg * ncnegfactor > lnumcache) 1832 cache_negative_zap_one(); 1833 cache_free(ndd); 1834 return; 1835 out_unlock_free: 1836 cache_enter_unlock(&cel); 1837 cache_free(ncp); 1838 return; 1839 } 1840 1841 static u_int 1842 cache_roundup_2(u_int val) 1843 { 1844 u_int res; 1845 1846 for (res = 1; res <= val; res <<= 1) 1847 continue; 1848 1849 return (res); 1850 } 1851 1852 /* 1853 * Name cache initialization, from vfs_init() when we are booting 1854 */ 1855 static void 1856 nchinit(void *dummy __unused) 1857 { 1858 u_int i; 1859 1860 cache_zone_small = uma_zcreate("S VFS Cache", 1861 sizeof(struct namecache) + CACHE_PATH_CUTOFF + 1, 1862 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache), 1863 UMA_ZONE_ZINIT); 1864 cache_zone_small_ts = uma_zcreate("STS VFS Cache", 1865 sizeof(struct namecache_ts) + CACHE_PATH_CUTOFF + 1, 1866 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache_ts), 1867 UMA_ZONE_ZINIT); 1868 cache_zone_large = uma_zcreate("L VFS Cache", 1869 sizeof(struct namecache) + NAME_MAX + 1, 1870 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache), 1871 UMA_ZONE_ZINIT); 1872 cache_zone_large_ts = uma_zcreate("LTS VFS Cache", 1873 sizeof(struct namecache_ts) + NAME_MAX + 1, 1874 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache_ts), 1875 UMA_ZONE_ZINIT); 1876 1877 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash); 1878 ncbuckethash = cache_roundup_2(mp_ncpus * 64) - 1; 1879 if (ncbuckethash > nchash) 1880 ncbuckethash = nchash; 1881 bucketlocks = malloc(sizeof(*bucketlocks) * numbucketlocks, M_VFSCACHE, 1882 M_WAITOK | M_ZERO); 1883 for (i = 0; i < numbucketlocks; i++) 1884 rw_init_flags(&bucketlocks[i], "ncbuc", RW_DUPOK | RW_RECURSE); 1885 ncvnodehash = cache_roundup_2(mp_ncpus * 64) - 1; 1886 vnodelocks = malloc(sizeof(*vnodelocks) * numvnodelocks, M_VFSCACHE, 1887 M_WAITOK | M_ZERO); 1888 for (i = 0; i < numvnodelocks; i++) 1889 mtx_init(&vnodelocks[i], "ncvn", NULL, MTX_DUPOK | MTX_RECURSE); 1890 ncpurgeminvnodes = numbucketlocks; 1891 1892 ncneghash = 3; 1893 neglists = malloc(sizeof(*neglists) * numneglists, M_VFSCACHE, 1894 M_WAITOK | M_ZERO); 1895 for (i = 0; i < numneglists; i++) { 1896 mtx_init(&neglists[i].nl_lock, "ncnegl", NULL, MTX_DEF); 1897 TAILQ_INIT(&neglists[i].nl_list); 1898 } 1899 mtx_init(&ncneg_hot.nl_lock, "ncneglh", NULL, MTX_DEF); 1900 TAILQ_INIT(&ncneg_hot.nl_list); 1901 1902 mtx_init(&ncneg_shrink_lock, "ncnegs", NULL, MTX_DEF); 1903 1904 numcalls = counter_u64_alloc(M_WAITOK); 1905 dothits = counter_u64_alloc(M_WAITOK); 1906 dotdothits = counter_u64_alloc(M_WAITOK); 1907 numchecks = counter_u64_alloc(M_WAITOK); 1908 nummiss = counter_u64_alloc(M_WAITOK); 1909 nummisszap = counter_u64_alloc(M_WAITOK); 1910 numposzaps = counter_u64_alloc(M_WAITOK); 1911 numposhits = counter_u64_alloc(M_WAITOK); 1912 numnegzaps = counter_u64_alloc(M_WAITOK); 1913 numneghits = counter_u64_alloc(M_WAITOK); 1914 numfullpathcalls = counter_u64_alloc(M_WAITOK); 1915 numfullpathfail1 = counter_u64_alloc(M_WAITOK); 1916 numfullpathfail2 = counter_u64_alloc(M_WAITOK); 1917 numfullpathfail4 = counter_u64_alloc(M_WAITOK); 1918 numfullpathfound = counter_u64_alloc(M_WAITOK); 1919 } 1920 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL); 1921 1922 void 1923 cache_changesize(int newmaxvnodes) 1924 { 1925 struct nchashhead *new_nchashtbl, *old_nchashtbl; 1926 u_long new_nchash, old_nchash; 1927 struct namecache *ncp; 1928 uint32_t hash; 1929 int i; 1930 1931 newmaxvnodes = cache_roundup_2(newmaxvnodes * 2); 1932 if (newmaxvnodes < numbucketlocks) 1933 newmaxvnodes = numbucketlocks; 1934 1935 new_nchashtbl = hashinit(newmaxvnodes, M_VFSCACHE, &new_nchash); 1936 /* If same hash table size, nothing to do */ 1937 if (nchash == new_nchash) { 1938 free(new_nchashtbl, M_VFSCACHE); 1939 return; 1940 } 1941 /* 1942 * Move everything from the old hash table to the new table. 1943 * None of the namecache entries in the table can be removed 1944 * because to do so, they have to be removed from the hash table. 1945 */ 1946 cache_lock_all_vnodes(); 1947 cache_lock_all_buckets(); 1948 old_nchashtbl = nchashtbl; 1949 old_nchash = nchash; 1950 nchashtbl = new_nchashtbl; 1951 nchash = new_nchash; 1952 for (i = 0; i <= old_nchash; i++) { 1953 while ((ncp = LIST_FIRST(&old_nchashtbl[i])) != NULL) { 1954 hash = cache_get_hash(ncp->nc_name, ncp->nc_nlen, 1955 ncp->nc_dvp); 1956 LIST_REMOVE(ncp, nc_hash); 1957 LIST_INSERT_HEAD(NCHHASH(hash), ncp, nc_hash); 1958 } 1959 } 1960 cache_unlock_all_buckets(); 1961 cache_unlock_all_vnodes(); 1962 free(old_nchashtbl, M_VFSCACHE); 1963 } 1964 1965 /* 1966 * Invalidate all entries to a particular vnode. 1967 */ 1968 void 1969 cache_purge(struct vnode *vp) 1970 { 1971 TAILQ_HEAD(, namecache) ncps; 1972 struct namecache *ncp, *nnp; 1973 struct mtx *vlp, *vlp2; 1974 1975 CTR1(KTR_VFS, "cache_purge(%p)", vp); 1976 SDT_PROBE1(vfs, namecache, purge, done, vp); 1977 if (LIST_EMPTY(&vp->v_cache_src) && TAILQ_EMPTY(&vp->v_cache_dst) && 1978 vp->v_cache_dd == NULL) 1979 return; 1980 TAILQ_INIT(&ncps); 1981 vlp = VP2VNODELOCK(vp); 1982 vlp2 = NULL; 1983 mtx_lock(vlp); 1984 retry: 1985 while (!LIST_EMPTY(&vp->v_cache_src)) { 1986 ncp = LIST_FIRST(&vp->v_cache_src); 1987 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 1988 goto retry; 1989 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 1990 } 1991 while (!TAILQ_EMPTY(&vp->v_cache_dst)) { 1992 ncp = TAILQ_FIRST(&vp->v_cache_dst); 1993 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 1994 goto retry; 1995 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 1996 } 1997 ncp = vp->v_cache_dd; 1998 if (ncp != NULL) { 1999 KASSERT(ncp->nc_flag & NCF_ISDOTDOT, 2000 ("lost dotdot link")); 2001 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 2002 goto retry; 2003 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 2004 } 2005 KASSERT(vp->v_cache_dd == NULL, ("incomplete purge")); 2006 mtx_unlock(vlp); 2007 if (vlp2 != NULL) 2008 mtx_unlock(vlp2); 2009 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { 2010 cache_free(ncp); 2011 } 2012 } 2013 2014 /* 2015 * Invalidate all negative entries for a particular directory vnode. 2016 */ 2017 void 2018 cache_purge_negative(struct vnode *vp) 2019 { 2020 TAILQ_HEAD(, namecache) ncps; 2021 struct namecache *ncp, *nnp; 2022 struct mtx *vlp; 2023 2024 CTR1(KTR_VFS, "cache_purge_negative(%p)", vp); 2025 SDT_PROBE1(vfs, namecache, purge_negative, done, vp); 2026 if (LIST_EMPTY(&vp->v_cache_src)) 2027 return; 2028 TAILQ_INIT(&ncps); 2029 vlp = VP2VNODELOCK(vp); 2030 mtx_lock(vlp); 2031 LIST_FOREACH_SAFE(ncp, &vp->v_cache_src, nc_src, nnp) { 2032 if (!(ncp->nc_flag & NCF_NEGATIVE)) 2033 continue; 2034 cache_zap_negative_locked_vnode_kl(ncp, vp); 2035 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 2036 } 2037 mtx_unlock(vlp); 2038 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { 2039 cache_free(ncp); 2040 } 2041 } 2042 2043 /* 2044 * Flush all entries referencing a particular filesystem. 2045 */ 2046 void 2047 cache_purgevfs(struct mount *mp, bool force) 2048 { 2049 TAILQ_HEAD(, namecache) ncps; 2050 struct mtx *vlp1, *vlp2; 2051 struct rwlock *blp; 2052 struct nchashhead *bucket; 2053 struct namecache *ncp, *nnp; 2054 u_long i, j, n_nchash; 2055 int error; 2056 2057 /* Scan hash tables for applicable entries */ 2058 SDT_PROBE1(vfs, namecache, purgevfs, done, mp); 2059 if (!force && mp->mnt_nvnodelistsize <= ncpurgeminvnodes) 2060 return; 2061 TAILQ_INIT(&ncps); 2062 n_nchash = nchash + 1; 2063 vlp1 = vlp2 = NULL; 2064 for (i = 0; i < numbucketlocks; i++) { 2065 blp = (struct rwlock *)&bucketlocks[i]; 2066 rw_wlock(blp); 2067 for (j = i; j < n_nchash; j += numbucketlocks) { 2068 retry: 2069 bucket = &nchashtbl[j]; 2070 LIST_FOREACH_SAFE(ncp, bucket, nc_hash, nnp) { 2071 cache_assert_bucket_locked(ncp, RA_WLOCKED); 2072 if (ncp->nc_dvp->v_mount != mp) 2073 continue; 2074 error = cache_zap_wlocked_bucket_kl(ncp, blp, 2075 &vlp1, &vlp2); 2076 if (error != 0) 2077 goto retry; 2078 TAILQ_INSERT_HEAD(&ncps, ncp, nc_dst); 2079 } 2080 } 2081 rw_wunlock(blp); 2082 if (vlp1 == NULL && vlp2 == NULL) 2083 cache_maybe_yield(); 2084 } 2085 if (vlp1 != NULL) 2086 mtx_unlock(vlp1); 2087 if (vlp2 != NULL) 2088 mtx_unlock(vlp2); 2089 2090 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { 2091 cache_free(ncp); 2092 } 2093 } 2094 2095 /* 2096 * Perform canonical checks and cache lookup and pass on to filesystem 2097 * through the vop_cachedlookup only if needed. 2098 */ 2099 2100 int 2101 vfs_cache_lookup(struct vop_lookup_args *ap) 2102 { 2103 struct vnode *dvp; 2104 int error; 2105 struct vnode **vpp = ap->a_vpp; 2106 struct componentname *cnp = ap->a_cnp; 2107 struct ucred *cred = cnp->cn_cred; 2108 int flags = cnp->cn_flags; 2109 struct thread *td = cnp->cn_thread; 2110 2111 *vpp = NULL; 2112 dvp = ap->a_dvp; 2113 2114 if (dvp->v_type != VDIR) 2115 return (ENOTDIR); 2116 2117 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && 2118 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 2119 return (EROFS); 2120 2121 error = VOP_ACCESS(dvp, VEXEC, cred, td); 2122 if (error) 2123 return (error); 2124 2125 error = cache_lookup(dvp, vpp, cnp, NULL, NULL); 2126 if (error == 0) 2127 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); 2128 if (error == -1) 2129 return (0); 2130 return (error); 2131 } 2132 2133 /* 2134 * XXX All of these sysctls would probably be more productive dead. 2135 */ 2136 static int __read_mostly disablecwd; 2137 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, 2138 "Disable the getcwd syscall"); 2139 2140 /* Implementation of the getcwd syscall. */ 2141 int 2142 sys___getcwd(struct thread *td, struct __getcwd_args *uap) 2143 { 2144 2145 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen, 2146 MAXPATHLEN)); 2147 } 2148 2149 int 2150 kern___getcwd(struct thread *td, char *buf, enum uio_seg bufseg, size_t buflen, 2151 size_t path_max) 2152 { 2153 char *bp, *tmpbuf; 2154 struct filedesc *fdp; 2155 struct vnode *cdir, *rdir; 2156 int error; 2157 2158 if (__predict_false(disablecwd)) 2159 return (ENODEV); 2160 if (__predict_false(buflen < 2)) 2161 return (EINVAL); 2162 if (buflen > path_max) 2163 buflen = path_max; 2164 2165 tmpbuf = malloc(buflen, M_TEMP, M_WAITOK); 2166 fdp = td->td_proc->p_fd; 2167 FILEDESC_SLOCK(fdp); 2168 cdir = fdp->fd_cdir; 2169 vrefact(cdir); 2170 rdir = fdp->fd_rdir; 2171 vrefact(rdir); 2172 FILEDESC_SUNLOCK(fdp); 2173 error = vn_fullpath1(td, cdir, rdir, tmpbuf, &bp, buflen); 2174 vrele(rdir); 2175 vrele(cdir); 2176 2177 if (!error) { 2178 if (bufseg == UIO_SYSSPACE) 2179 bcopy(bp, buf, strlen(bp) + 1); 2180 else 2181 error = copyout(bp, buf, strlen(bp) + 1); 2182 #ifdef KTRACE 2183 if (KTRPOINT(curthread, KTR_NAMEI)) 2184 ktrnamei(bp); 2185 #endif 2186 } 2187 free(tmpbuf, M_TEMP); 2188 return (error); 2189 } 2190 2191 /* 2192 * Thus begins the fullpath magic. 2193 */ 2194 2195 static int __read_mostly disablefullpath; 2196 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0, 2197 "Disable the vn_fullpath function"); 2198 2199 /* 2200 * Retrieve the full filesystem path that correspond to a vnode from the name 2201 * cache (if available) 2202 */ 2203 int 2204 vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf) 2205 { 2206 char *buf; 2207 struct filedesc *fdp; 2208 struct vnode *rdir; 2209 int error; 2210 2211 if (__predict_false(disablefullpath)) 2212 return (ENODEV); 2213 if (__predict_false(vn == NULL)) 2214 return (EINVAL); 2215 2216 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 2217 fdp = td->td_proc->p_fd; 2218 FILEDESC_SLOCK(fdp); 2219 rdir = fdp->fd_rdir; 2220 vrefact(rdir); 2221 FILEDESC_SUNLOCK(fdp); 2222 error = vn_fullpath1(td, vn, rdir, buf, retbuf, MAXPATHLEN); 2223 vrele(rdir); 2224 2225 if (!error) 2226 *freebuf = buf; 2227 else 2228 free(buf, M_TEMP); 2229 return (error); 2230 } 2231 2232 /* 2233 * This function is similar to vn_fullpath, but it attempts to lookup the 2234 * pathname relative to the global root mount point. This is required for the 2235 * auditing sub-system, as audited pathnames must be absolute, relative to the 2236 * global root mount point. 2237 */ 2238 int 2239 vn_fullpath_global(struct thread *td, struct vnode *vn, 2240 char **retbuf, char **freebuf) 2241 { 2242 char *buf; 2243 int error; 2244 2245 if (__predict_false(disablefullpath)) 2246 return (ENODEV); 2247 if (__predict_false(vn == NULL)) 2248 return (EINVAL); 2249 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 2250 error = vn_fullpath1(td, vn, rootvnode, buf, retbuf, MAXPATHLEN); 2251 if (!error) 2252 *freebuf = buf; 2253 else 2254 free(buf, M_TEMP); 2255 return (error); 2256 } 2257 2258 int 2259 vn_vptocnp(struct vnode **vp, struct ucred *cred, char *buf, u_int *buflen) 2260 { 2261 struct vnode *dvp; 2262 struct namecache *ncp; 2263 struct mtx *vlp; 2264 int error; 2265 2266 vlp = VP2VNODELOCK(*vp); 2267 mtx_lock(vlp); 2268 TAILQ_FOREACH(ncp, &((*vp)->v_cache_dst), nc_dst) { 2269 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 2270 break; 2271 } 2272 if (ncp != NULL) { 2273 if (*buflen < ncp->nc_nlen) { 2274 mtx_unlock(vlp); 2275 vrele(*vp); 2276 counter_u64_add(numfullpathfail4, 1); 2277 error = ENOMEM; 2278 SDT_PROBE3(vfs, namecache, fullpath, return, error, 2279 vp, NULL); 2280 return (error); 2281 } 2282 *buflen -= ncp->nc_nlen; 2283 memcpy(buf + *buflen, ncp->nc_name, ncp->nc_nlen); 2284 SDT_PROBE3(vfs, namecache, fullpath, hit, ncp->nc_dvp, 2285 ncp->nc_name, vp); 2286 dvp = *vp; 2287 *vp = ncp->nc_dvp; 2288 vref(*vp); 2289 mtx_unlock(vlp); 2290 vrele(dvp); 2291 return (0); 2292 } 2293 SDT_PROBE1(vfs, namecache, fullpath, miss, vp); 2294 2295 mtx_unlock(vlp); 2296 vn_lock(*vp, LK_SHARED | LK_RETRY); 2297 error = VOP_VPTOCNP(*vp, &dvp, cred, buf, buflen); 2298 vput(*vp); 2299 if (error) { 2300 counter_u64_add(numfullpathfail2, 1); 2301 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); 2302 return (error); 2303 } 2304 2305 *vp = dvp; 2306 if (dvp->v_iflag & VI_DOOMED) { 2307 /* forced unmount */ 2308 vrele(dvp); 2309 error = ENOENT; 2310 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); 2311 return (error); 2312 } 2313 /* 2314 * *vp has its use count incremented still. 2315 */ 2316 2317 return (0); 2318 } 2319 2320 /* 2321 * The magic behind kern___getcwd() and vn_fullpath(). 2322 */ 2323 static int 2324 vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 2325 char *buf, char **retbuf, u_int buflen) 2326 { 2327 int error, slash_prefixed; 2328 #ifdef KDTRACE_HOOKS 2329 struct vnode *startvp = vp; 2330 #endif 2331 struct vnode *vp1; 2332 2333 buflen--; 2334 buf[buflen] = '\0'; 2335 error = 0; 2336 slash_prefixed = 0; 2337 2338 SDT_PROBE1(vfs, namecache, fullpath, entry, vp); 2339 counter_u64_add(numfullpathcalls, 1); 2340 vref(vp); 2341 if (vp->v_type != VDIR) { 2342 error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen); 2343 if (error) 2344 return (error); 2345 if (buflen == 0) { 2346 vrele(vp); 2347 return (ENOMEM); 2348 } 2349 buf[--buflen] = '/'; 2350 slash_prefixed = 1; 2351 } 2352 while (vp != rdir && vp != rootvnode) { 2353 /* 2354 * The vp vnode must be already fully constructed, 2355 * since it is either found in namecache or obtained 2356 * from VOP_VPTOCNP(). We may test for VV_ROOT safely 2357 * without obtaining the vnode lock. 2358 */ 2359 if ((vp->v_vflag & VV_ROOT) != 0) { 2360 vn_lock(vp, LK_RETRY | LK_SHARED); 2361 2362 /* 2363 * With the vnode locked, check for races with 2364 * unmount, forced or not. Note that we 2365 * already verified that vp is not equal to 2366 * the root vnode, which means that 2367 * mnt_vnodecovered can be NULL only for the 2368 * case of unmount. 2369 */ 2370 if ((vp->v_iflag & VI_DOOMED) != 0 || 2371 (vp1 = vp->v_mount->mnt_vnodecovered) == NULL || 2372 vp1->v_mountedhere != vp->v_mount) { 2373 vput(vp); 2374 error = ENOENT; 2375 SDT_PROBE3(vfs, namecache, fullpath, return, 2376 error, vp, NULL); 2377 break; 2378 } 2379 2380 vref(vp1); 2381 vput(vp); 2382 vp = vp1; 2383 continue; 2384 } 2385 if (vp->v_type != VDIR) { 2386 vrele(vp); 2387 counter_u64_add(numfullpathfail1, 1); 2388 error = ENOTDIR; 2389 SDT_PROBE3(vfs, namecache, fullpath, return, 2390 error, vp, NULL); 2391 break; 2392 } 2393 error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen); 2394 if (error) 2395 break; 2396 if (buflen == 0) { 2397 vrele(vp); 2398 error = ENOMEM; 2399 SDT_PROBE3(vfs, namecache, fullpath, return, error, 2400 startvp, NULL); 2401 break; 2402 } 2403 buf[--buflen] = '/'; 2404 slash_prefixed = 1; 2405 } 2406 if (error) 2407 return (error); 2408 if (!slash_prefixed) { 2409 if (buflen == 0) { 2410 vrele(vp); 2411 counter_u64_add(numfullpathfail4, 1); 2412 SDT_PROBE3(vfs, namecache, fullpath, return, ENOMEM, 2413 startvp, NULL); 2414 return (ENOMEM); 2415 } 2416 buf[--buflen] = '/'; 2417 } 2418 counter_u64_add(numfullpathfound, 1); 2419 vrele(vp); 2420 2421 SDT_PROBE3(vfs, namecache, fullpath, return, 0, startvp, buf + buflen); 2422 *retbuf = buf + buflen; 2423 return (0); 2424 } 2425 2426 struct vnode * 2427 vn_dir_dd_ino(struct vnode *vp) 2428 { 2429 struct namecache *ncp; 2430 struct vnode *ddvp; 2431 struct mtx *vlp; 2432 2433 ASSERT_VOP_LOCKED(vp, "vn_dir_dd_ino"); 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 continue; 2439 ddvp = ncp->nc_dvp; 2440 vhold(ddvp); 2441 mtx_unlock(vlp); 2442 if (vget(ddvp, LK_SHARED | LK_NOWAIT | LK_VNHELD, curthread)) 2443 return (NULL); 2444 return (ddvp); 2445 } 2446 mtx_unlock(vlp); 2447 return (NULL); 2448 } 2449 2450 int 2451 vn_commname(struct vnode *vp, char *buf, u_int buflen) 2452 { 2453 struct namecache *ncp; 2454 struct mtx *vlp; 2455 int l; 2456 2457 vlp = VP2VNODELOCK(vp); 2458 mtx_lock(vlp); 2459 TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst) 2460 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 2461 break; 2462 if (ncp == NULL) { 2463 mtx_unlock(vlp); 2464 return (ENOENT); 2465 } 2466 l = min(ncp->nc_nlen, buflen - 1); 2467 memcpy(buf, ncp->nc_name, l); 2468 mtx_unlock(vlp); 2469 buf[l] = '\0'; 2470 return (0); 2471 } 2472 2473 /* 2474 * This function updates path string to vnode's full global path 2475 * and checks the size of the new path string against the pathlen argument. 2476 * 2477 * Requires a locked, referenced vnode. 2478 * Vnode is re-locked on success or ENODEV, otherwise unlocked. 2479 * 2480 * If sysctl debug.disablefullpath is set, ENODEV is returned, 2481 * vnode is left locked and path remain untouched. 2482 * 2483 * If vp is a directory, the call to vn_fullpath_global() always succeeds 2484 * because it falls back to the ".." lookup if the namecache lookup fails. 2485 */ 2486 int 2487 vn_path_to_global_path(struct thread *td, struct vnode *vp, char *path, 2488 u_int pathlen) 2489 { 2490 struct nameidata nd; 2491 struct vnode *vp1; 2492 char *rpath, *fbuf; 2493 int error; 2494 2495 ASSERT_VOP_ELOCKED(vp, __func__); 2496 2497 /* Return ENODEV if sysctl debug.disablefullpath==1 */ 2498 if (__predict_false(disablefullpath)) 2499 return (ENODEV); 2500 2501 /* Construct global filesystem path from vp. */ 2502 VOP_UNLOCK(vp, 0); 2503 error = vn_fullpath_global(td, vp, &rpath, &fbuf); 2504 2505 if (error != 0) { 2506 vrele(vp); 2507 return (error); 2508 } 2509 2510 if (strlen(rpath) >= pathlen) { 2511 vrele(vp); 2512 error = ENAMETOOLONG; 2513 goto out; 2514 } 2515 2516 /* 2517 * Re-lookup the vnode by path to detect a possible rename. 2518 * As a side effect, the vnode is relocked. 2519 * If vnode was renamed, return ENOENT. 2520 */ 2521 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1, 2522 UIO_SYSSPACE, path, td); 2523 error = namei(&nd); 2524 if (error != 0) { 2525 vrele(vp); 2526 goto out; 2527 } 2528 NDFREE(&nd, NDF_ONLY_PNBUF); 2529 vp1 = nd.ni_vp; 2530 vrele(vp); 2531 if (vp1 == vp) 2532 strcpy(path, rpath); 2533 else { 2534 vput(vp1); 2535 error = ENOENT; 2536 } 2537 2538 out: 2539 free(fbuf, M_TEMP); 2540 return (error); 2541 } 2542 2543 #ifdef DDB 2544 static void 2545 db_print_vpath(struct vnode *vp) 2546 { 2547 2548 while (vp != NULL) { 2549 db_printf("%p: ", vp); 2550 if (vp == rootvnode) { 2551 db_printf("/"); 2552 vp = NULL; 2553 } else { 2554 if (vp->v_vflag & VV_ROOT) { 2555 db_printf("<mount point>"); 2556 vp = vp->v_mount->mnt_vnodecovered; 2557 } else { 2558 struct namecache *ncp; 2559 char *ncn; 2560 int i; 2561 2562 ncp = TAILQ_FIRST(&vp->v_cache_dst); 2563 if (ncp != NULL) { 2564 ncn = ncp->nc_name; 2565 for (i = 0; i < ncp->nc_nlen; i++) 2566 db_printf("%c", *ncn++); 2567 vp = ncp->nc_dvp; 2568 } else { 2569 vp = NULL; 2570 } 2571 } 2572 } 2573 db_printf("\n"); 2574 } 2575 2576 return; 2577 } 2578 2579 DB_SHOW_COMMAND(vpath, db_show_vpath) 2580 { 2581 struct vnode *vp; 2582 2583 if (!have_addr) { 2584 db_printf("usage: show vpath <struct vnode *>\n"); 2585 return; 2586 } 2587 2588 vp = (struct vnode *)addr; 2589 db_print_vpath(vp); 2590 } 2591 2592 #endif 2593