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/ktr.h> 50 #include <sys/lock.h> 51 #include <sys/malloc.h> 52 #include <sys/fcntl.h> 53 #include <sys/mount.h> 54 #include <sys/namei.h> 55 #include <sys/proc.h> 56 #include <sys/rwlock.h> 57 #include <sys/sdt.h> 58 #include <sys/smp.h> 59 #include <sys/syscallsubr.h> 60 #include <sys/sysctl.h> 61 #include <sys/sysproto.h> 62 #include <sys/vnode.h> 63 #ifdef KTRACE 64 #include <sys/ktrace.h> 65 #endif 66 67 #ifdef DDB 68 #include <ddb/ddb.h> 69 #endif 70 71 #include <vm/uma.h> 72 73 SDT_PROVIDER_DECLARE(vfs); 74 SDT_PROBE_DEFINE3(vfs, namecache, enter, done, "struct vnode *", "char *", 75 "struct vnode *"); 76 SDT_PROBE_DEFINE2(vfs, namecache, enter_negative, done, "struct vnode *", 77 "char *"); 78 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, entry, "struct vnode *"); 79 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, hit, "struct vnode *", 80 "char *", "struct vnode *"); 81 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, miss, "struct vnode *"); 82 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, return, "int", 83 "struct vnode *", "char *"); 84 SDT_PROBE_DEFINE3(vfs, namecache, lookup, hit, "struct vnode *", "char *", 85 "struct vnode *"); 86 SDT_PROBE_DEFINE2(vfs, namecache, lookup, hit__negative, 87 "struct vnode *", "char *"); 88 SDT_PROBE_DEFINE2(vfs, namecache, lookup, miss, "struct vnode *", 89 "char *"); 90 SDT_PROBE_DEFINE1(vfs, namecache, purge, done, "struct vnode *"); 91 SDT_PROBE_DEFINE1(vfs, namecache, purge_negative, done, "struct vnode *"); 92 SDT_PROBE_DEFINE1(vfs, namecache, purgevfs, done, "struct mount *"); 93 SDT_PROBE_DEFINE3(vfs, namecache, zap, done, "struct vnode *", "char *", 94 "struct vnode *"); 95 SDT_PROBE_DEFINE2(vfs, namecache, zap_negative, done, "struct vnode *", 96 "char *"); 97 SDT_PROBE_DEFINE2(vfs, namecache, shrink_negative, done, "struct vnode *", 98 "char *"); 99 100 /* 101 * This structure describes the elements in the cache of recent 102 * names looked up by namei. 103 */ 104 105 struct namecache { 106 LIST_ENTRY(namecache) nc_hash; /* hash chain */ 107 LIST_ENTRY(namecache) nc_src; /* source vnode list */ 108 TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */ 109 struct vnode *nc_dvp; /* vnode of parent of name */ 110 union { 111 struct vnode *nu_vp; /* vnode the name refers to */ 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 134 135 /* 136 * Flags in namecache.nc_flag 137 */ 138 #define NCF_WHITE 0x01 139 #define NCF_ISDOTDOT 0x02 140 #define NCF_TS 0x04 141 #define NCF_DTS 0x08 142 #define NCF_DVDROP 0x10 143 #define NCF_NEGATIVE 0x20 144 #define NCF_HOTNEGATIVE 0x40 145 146 /* 147 * Name caching works as follows: 148 * 149 * Names found by directory scans are retained in a cache 150 * for future reference. It is managed LRU, so frequently 151 * used names will hang around. Cache is indexed by hash value 152 * obtained from (dvp, name) where dvp refers to the directory 153 * containing name. 154 * 155 * If it is a "negative" entry, (i.e. for a name that is known NOT to 156 * exist) the vnode pointer will be NULL. 157 * 158 * Upon reaching the last segment of a path, if the reference 159 * is for DELETE, or NOCACHE is set (rewrite), and the 160 * name is located in the cache, it will be dropped. 161 * 162 * These locks are used (in the order in which they can be taken): 163 * NAME TYPE ROLE 164 * vnodelock mtx vnode lists and v_cache_dd field protection 165 * bucketlock rwlock for access to given set of hash buckets 166 * neglist mtx negative entry LRU management 167 * 168 * Additionally, ncneg_shrink_lock mtx is used to have at most one thread 169 * shrinking the LRU list. 170 * 171 * It is legal to take multiple vnodelock and bucketlock locks. The locking 172 * order is lower address first. Both are recursive. 173 * 174 * "." lookups are lockless. 175 * 176 * ".." and vnode -> name lookups require vnodelock. 177 * 178 * name -> vnode lookup requires the relevant bucketlock to be held for reading. 179 * 180 * Insertions and removals of entries require involved vnodes and bucketlocks 181 * to be write-locked to prevent other threads from seeing the entry. 182 * 183 * Some lookups result in removal of the found entry (e.g. getting rid of a 184 * negative entry with the intent to create a positive one), which poses a 185 * problem when multiple threads reach the state. Similarly, two different 186 * threads can purge two different vnodes and try to remove the same name. 187 * 188 * If the already held vnode lock is lower than the second required lock, we 189 * can just take the other lock. However, in the opposite case, this could 190 * deadlock. As such, this is resolved by trylocking and if that fails unlocking 191 * the first node, locking everything in order and revalidating the state. 192 */ 193 194 /* 195 * Structures associated with name caching. 196 */ 197 #define NCHHASH(hash) \ 198 (&nchashtbl[(hash) & nchash]) 199 static __read_mostly LIST_HEAD(nchashhead, namecache) *nchashtbl;/* Hash Table */ 200 static u_long __read_mostly nchash; /* size of hash table */ 201 SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, 202 "Size of namecache hash table"); 203 static u_long __read_mostly ncnegfactor = 5; /* ratio of negative entries */ 204 SYSCTL_ULONG(_vfs, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, 205 "Ratio of negative namecache entries"); 206 static u_long __exclusive_cache_line numneg; /* number of negative entries allocated */ 207 static u_long __exclusive_cache_line numcache;/* number of cache entries allocated */ 208 static u_long __exclusive_cache_line numcachehv;/* number of cache entries with vnodes held */ 209 u_int 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 ncsize; /* the size as computed on creation or resizing */ 216 217 struct nchstats nchstats; /* cache effectiveness statistics */ 218 219 static struct mtx __exclusive_cache_line ncneg_shrink_lock; 220 static int shrink_list_turn; 221 222 struct neglist { 223 struct mtx nl_lock; 224 TAILQ_HEAD(, namecache) nl_list; 225 } __aligned(CACHE_LINE_SIZE); 226 227 static struct neglist __read_mostly *neglists; 228 static struct neglist ncneg_hot; 229 static u_long numhotneg; 230 231 #define numneglists (ncneghash + 1) 232 static u_int __read_mostly ncneghash; 233 static inline struct neglist * 234 NCP2NEGLIST(struct namecache *ncp) 235 { 236 237 return (&neglists[(((uintptr_t)(ncp) >> 8) & ncneghash)]); 238 } 239 240 #define numbucketlocks (ncbuckethash + 1) 241 static u_int __read_mostly ncbuckethash; 242 static struct rwlock_padalign __read_mostly *bucketlocks; 243 #define HASH2BUCKETLOCK(hash) \ 244 ((struct rwlock *)(&bucketlocks[((hash) & ncbuckethash)])) 245 246 #define numvnodelocks (ncvnodehash + 1) 247 static u_int __read_mostly ncvnodehash; 248 static struct mtx __read_mostly *vnodelocks; 249 static inline struct mtx * 250 VP2VNODELOCK(struct vnode *vp) 251 { 252 253 return (&vnodelocks[(((uintptr_t)(vp) >> 8) & ncvnodehash)]); 254 } 255 256 /* 257 * UMA zones for the VFS cache. 258 * 259 * The small cache is used for entries with short names, which are the 260 * most common. The large cache is used for entries which are too big to 261 * fit in the small cache. 262 */ 263 static uma_zone_t __read_mostly cache_zone_small; 264 static uma_zone_t __read_mostly cache_zone_small_ts; 265 static uma_zone_t __read_mostly cache_zone_large; 266 static uma_zone_t __read_mostly cache_zone_large_ts; 267 268 #define CACHE_PATH_CUTOFF 35 269 270 static struct namecache * 271 cache_alloc(int len, int ts) 272 { 273 struct namecache_ts *ncp_ts; 274 struct namecache *ncp; 275 276 if (__predict_false(ts)) { 277 if (len <= CACHE_PATH_CUTOFF) 278 ncp_ts = uma_zalloc(cache_zone_small_ts, M_WAITOK); 279 else 280 ncp_ts = uma_zalloc(cache_zone_large_ts, M_WAITOK); 281 ncp = &ncp_ts->nc_nc; 282 } else { 283 if (len <= CACHE_PATH_CUTOFF) 284 ncp = uma_zalloc(cache_zone_small, M_WAITOK); 285 else 286 ncp = uma_zalloc(cache_zone_large, M_WAITOK); 287 } 288 return (ncp); 289 } 290 291 static void 292 cache_free(struct namecache *ncp) 293 { 294 struct namecache_ts *ncp_ts; 295 296 if (ncp == NULL) 297 return; 298 if ((ncp->nc_flag & NCF_DVDROP) != 0) 299 vdrop(ncp->nc_dvp); 300 if (__predict_false(ncp->nc_flag & NCF_TS)) { 301 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); 302 if (ncp->nc_nlen <= CACHE_PATH_CUTOFF) 303 uma_zfree(cache_zone_small_ts, ncp_ts); 304 else 305 uma_zfree(cache_zone_large_ts, ncp_ts); 306 } else { 307 if (ncp->nc_nlen <= CACHE_PATH_CUTOFF) 308 uma_zfree(cache_zone_small, ncp); 309 else 310 uma_zfree(cache_zone_large, ncp); 311 } 312 } 313 314 static void 315 cache_out_ts(struct namecache *ncp, struct timespec *tsp, int *ticksp) 316 { 317 struct namecache_ts *ncp_ts; 318 319 KASSERT((ncp->nc_flag & NCF_TS) != 0 || 320 (tsp == NULL && ticksp == NULL), 321 ("No NCF_TS")); 322 323 if (tsp == NULL && ticksp == NULL) 324 return; 325 326 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); 327 if (tsp != NULL) 328 *tsp = ncp_ts->nc_time; 329 if (ticksp != NULL) 330 *ticksp = ncp_ts->nc_ticks; 331 } 332 333 #ifdef DEBUG_CACHE 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 #endif 338 339 /* Export size information to userland */ 340 SYSCTL_INT(_debug_sizeof, OID_AUTO, namecache, CTLFLAG_RD, SYSCTL_NULL_INT_PTR, 341 sizeof(struct namecache), "sizeof(struct namecache)"); 342 343 /* 344 * The new name cache statistics 345 */ 346 static SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, 347 "Name cache statistics"); 348 #define STATNODE_ULONG(name, descr) \ 349 SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, descr); 350 #define STATNODE_COUNTER(name, descr) \ 351 static counter_u64_t __read_mostly name; \ 352 SYSCTL_COUNTER_U64(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, descr); 353 STATNODE_ULONG(numneg, "Number of negative cache entries"); 354 STATNODE_ULONG(numcache, "Number of cache entries"); 355 STATNODE_ULONG(numcachehv, "Number of namecache entries with vnodes held"); 356 STATNODE_COUNTER(numcalls, "Number of cache lookups"); 357 STATNODE_COUNTER(dothits, "Number of '.' hits"); 358 STATNODE_COUNTER(dotdothits, "Number of '..' hits"); 359 STATNODE_COUNTER(numchecks, "Number of checks in lookup"); 360 STATNODE_COUNTER(nummiss, "Number of cache misses"); 361 STATNODE_COUNTER(nummisszap, "Number of cache misses we do not want to cache"); 362 STATNODE_COUNTER(numposzaps, 363 "Number of cache hits (positive) we do not want to cache"); 364 STATNODE_COUNTER(numposhits, "Number of cache hits (positive)"); 365 STATNODE_COUNTER(numnegzaps, 366 "Number of cache hits (negative) we do not want to cache"); 367 STATNODE_COUNTER(numneghits, "Number of cache hits (negative)"); 368 /* These count for kern___getcwd(), too. */ 369 STATNODE_COUNTER(numfullpathcalls, "Number of fullpath search calls"); 370 STATNODE_COUNTER(numfullpathfail1, "Number of fullpath search errors (ENOTDIR)"); 371 STATNODE_COUNTER(numfullpathfail2, 372 "Number of fullpath search errors (VOP_VPTOCNP failures)"); 373 STATNODE_COUNTER(numfullpathfail4, "Number of fullpath search errors (ENOMEM)"); 374 STATNODE_COUNTER(numfullpathfound, "Number of successful fullpath calls"); 375 STATNODE_COUNTER(zap_and_exit_bucket_relock_success, 376 "Number of successful removals after relocking"); 377 static long zap_and_exit_bucket_fail; STATNODE_ULONG(zap_and_exit_bucket_fail, 378 "Number of times zap_and_exit failed to lock"); 379 static long zap_and_exit_bucket_fail2; STATNODE_ULONG(zap_and_exit_bucket_fail2, 380 "Number of times zap_and_exit failed to lock"); 381 static long cache_lock_vnodes_cel_3_failures; 382 STATNODE_ULONG(cache_lock_vnodes_cel_3_failures, 383 "Number of times 3-way vnode locking failed"); 384 STATNODE_ULONG(numhotneg, "Number of hot negative entries"); 385 STATNODE_COUNTER(numneg_evicted, 386 "Number of negative entries evicted when adding a new entry"); 387 STATNODE_COUNTER(shrinking_skipped, 388 "Number of times shrinking was already in progress"); 389 390 static void cache_zap_locked(struct namecache *ncp, bool neg_locked); 391 static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 392 char *buf, char **retbuf, u_int buflen); 393 394 static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); 395 396 static int cache_yield; 397 SYSCTL_INT(_vfs_cache, OID_AUTO, yield, CTLFLAG_RD, &cache_yield, 0, 398 "Number of times cache called yield"); 399 400 static void __noinline 401 cache_maybe_yield(void) 402 { 403 404 if (should_yield()) { 405 cache_yield++; 406 kern_yield(PRI_USER); 407 } 408 } 409 410 static inline void 411 cache_assert_vlp_locked(struct mtx *vlp) 412 { 413 414 if (vlp != NULL) 415 mtx_assert(vlp, MA_OWNED); 416 } 417 418 static inline void 419 cache_assert_vnode_locked(struct vnode *vp) 420 { 421 struct mtx *vlp; 422 423 vlp = VP2VNODELOCK(vp); 424 cache_assert_vlp_locked(vlp); 425 } 426 427 static uint32_t 428 cache_get_hash(char *name, u_char len, struct vnode *dvp) 429 { 430 uint32_t hash; 431 432 hash = fnv_32_buf(name, len, FNV1_32_INIT); 433 hash = fnv_32_buf(&dvp, sizeof(dvp), hash); 434 return (hash); 435 } 436 437 static inline struct rwlock * 438 NCP2BUCKETLOCK(struct namecache *ncp) 439 { 440 uint32_t hash; 441 442 hash = cache_get_hash(ncp->nc_name, ncp->nc_nlen, ncp->nc_dvp); 443 return (HASH2BUCKETLOCK(hash)); 444 } 445 446 #ifdef INVARIANTS 447 static void 448 cache_assert_bucket_locked(struct namecache *ncp, int mode) 449 { 450 struct rwlock *blp; 451 452 blp = NCP2BUCKETLOCK(ncp); 453 rw_assert(blp, mode); 454 } 455 #else 456 #define cache_assert_bucket_locked(x, y) do { } while (0) 457 #endif 458 459 #define cache_sort_vnodes(x, y) _cache_sort_vnodes((void **)(x), (void **)(y)) 460 static void 461 _cache_sort_vnodes(void **p1, void **p2) 462 { 463 void *tmp; 464 465 MPASS(*p1 != NULL || *p2 != NULL); 466 467 if (*p1 > *p2) { 468 tmp = *p2; 469 *p2 = *p1; 470 *p1 = tmp; 471 } 472 } 473 474 static void 475 cache_lock_all_buckets(void) 476 { 477 u_int i; 478 479 for (i = 0; i < numbucketlocks; i++) 480 rw_wlock(&bucketlocks[i]); 481 } 482 483 static void 484 cache_unlock_all_buckets(void) 485 { 486 u_int i; 487 488 for (i = 0; i < numbucketlocks; i++) 489 rw_wunlock(&bucketlocks[i]); 490 } 491 492 static void 493 cache_lock_all_vnodes(void) 494 { 495 u_int i; 496 497 for (i = 0; i < numvnodelocks; i++) 498 mtx_lock(&vnodelocks[i]); 499 } 500 501 static void 502 cache_unlock_all_vnodes(void) 503 { 504 u_int i; 505 506 for (i = 0; i < numvnodelocks; i++) 507 mtx_unlock(&vnodelocks[i]); 508 } 509 510 static int 511 cache_trylock_vnodes(struct mtx *vlp1, struct mtx *vlp2) 512 { 513 514 cache_sort_vnodes(&vlp1, &vlp2); 515 516 if (vlp1 != NULL) { 517 if (!mtx_trylock(vlp1)) 518 return (EAGAIN); 519 } 520 if (!mtx_trylock(vlp2)) { 521 if (vlp1 != NULL) 522 mtx_unlock(vlp1); 523 return (EAGAIN); 524 } 525 526 return (0); 527 } 528 529 static void 530 cache_lock_vnodes(struct mtx *vlp1, struct mtx *vlp2) 531 { 532 533 MPASS(vlp1 != NULL || vlp2 != NULL); 534 MPASS(vlp1 <= vlp2); 535 536 if (vlp1 != NULL) 537 mtx_lock(vlp1); 538 if (vlp2 != NULL) 539 mtx_lock(vlp2); 540 } 541 542 static void 543 cache_unlock_vnodes(struct mtx *vlp1, struct mtx *vlp2) 544 { 545 546 MPASS(vlp1 != NULL || vlp2 != NULL); 547 548 if (vlp1 != NULL) 549 mtx_unlock(vlp1); 550 if (vlp2 != NULL) 551 mtx_unlock(vlp2); 552 } 553 554 static int 555 sysctl_nchstats(SYSCTL_HANDLER_ARGS) 556 { 557 struct nchstats snap; 558 559 if (req->oldptr == NULL) 560 return (SYSCTL_OUT(req, 0, sizeof(snap))); 561 562 snap = nchstats; 563 snap.ncs_goodhits = counter_u64_fetch(numposhits); 564 snap.ncs_neghits = counter_u64_fetch(numneghits); 565 snap.ncs_badhits = counter_u64_fetch(numposzaps) + 566 counter_u64_fetch(numnegzaps); 567 snap.ncs_miss = counter_u64_fetch(nummisszap) + 568 counter_u64_fetch(nummiss); 569 570 return (SYSCTL_OUT(req, &snap, sizeof(snap))); 571 } 572 SYSCTL_PROC(_vfs_cache, OID_AUTO, nchstats, CTLTYPE_OPAQUE | CTLFLAG_RD | 573 CTLFLAG_MPSAFE, 0, 0, sysctl_nchstats, "LU", 574 "VFS cache effectiveness statistics"); 575 576 #ifdef DIAGNOSTIC 577 /* 578 * Grab an atomic snapshot of the name cache hash chain lengths 579 */ 580 static SYSCTL_NODE(_debug, OID_AUTO, hashstat, CTLFLAG_RW, NULL, 581 "hash table stats"); 582 583 static int 584 sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS) 585 { 586 struct nchashhead *ncpp; 587 struct namecache *ncp; 588 int i, error, n_nchash, *cntbuf; 589 590 retry: 591 n_nchash = nchash + 1; /* nchash is max index, not count */ 592 if (req->oldptr == NULL) 593 return SYSCTL_OUT(req, 0, n_nchash * sizeof(int)); 594 cntbuf = malloc(n_nchash * sizeof(int), M_TEMP, M_ZERO | M_WAITOK); 595 cache_lock_all_buckets(); 596 if (n_nchash != nchash + 1) { 597 cache_unlock_all_buckets(); 598 free(cntbuf, M_TEMP); 599 goto retry; 600 } 601 /* Scan hash tables counting entries */ 602 for (ncpp = nchashtbl, i = 0; i < n_nchash; ncpp++, i++) 603 LIST_FOREACH(ncp, ncpp, nc_hash) 604 cntbuf[i]++; 605 cache_unlock_all_buckets(); 606 for (error = 0, i = 0; i < n_nchash; i++) 607 if ((error = SYSCTL_OUT(req, &cntbuf[i], sizeof(int))) != 0) 608 break; 609 free(cntbuf, M_TEMP); 610 return (error); 611 } 612 SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD| 613 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_rawnchash, "S,int", 614 "nchash chain lengths"); 615 616 static int 617 sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS) 618 { 619 int error; 620 struct nchashhead *ncpp; 621 struct namecache *ncp; 622 int n_nchash; 623 int count, maxlength, used, pct; 624 625 if (!req->oldptr) 626 return SYSCTL_OUT(req, 0, 4 * sizeof(int)); 627 628 cache_lock_all_buckets(); 629 n_nchash = nchash + 1; /* nchash is max index, not count */ 630 used = 0; 631 maxlength = 0; 632 633 /* Scan hash tables for applicable entries */ 634 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { 635 count = 0; 636 LIST_FOREACH(ncp, ncpp, nc_hash) { 637 count++; 638 } 639 if (count) 640 used++; 641 if (maxlength < count) 642 maxlength = count; 643 } 644 n_nchash = nchash + 1; 645 cache_unlock_all_buckets(); 646 pct = (used * 100) / (n_nchash / 100); 647 error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash)); 648 if (error) 649 return (error); 650 error = SYSCTL_OUT(req, &used, sizeof(used)); 651 if (error) 652 return (error); 653 error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength)); 654 if (error) 655 return (error); 656 error = SYSCTL_OUT(req, &pct, sizeof(pct)); 657 if (error) 658 return (error); 659 return (0); 660 } 661 SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD| 662 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_nchash, "I", 663 "nchash statistics (number of total/used buckets, maximum chain length, usage percentage)"); 664 #endif 665 666 /* 667 * Negative entries management 668 * 669 * A variation of LRU scheme is used. New entries are hashed into one of 670 * numneglists cold lists. Entries get promoted to the hot list on first hit. 671 * 672 * The shrinker will demote hot list head and evict from the cold list in a 673 * round-robin manner. 674 */ 675 static void 676 cache_negative_hit(struct namecache *ncp) 677 { 678 struct neglist *neglist; 679 680 MPASS(ncp->nc_flag & NCF_NEGATIVE); 681 if (ncp->nc_flag & NCF_HOTNEGATIVE) 682 return; 683 neglist = NCP2NEGLIST(ncp); 684 mtx_lock(&ncneg_hot.nl_lock); 685 mtx_lock(&neglist->nl_lock); 686 if (!(ncp->nc_flag & NCF_HOTNEGATIVE)) { 687 numhotneg++; 688 TAILQ_REMOVE(&neglist->nl_list, ncp, nc_dst); 689 TAILQ_INSERT_TAIL(&ncneg_hot.nl_list, ncp, nc_dst); 690 ncp->nc_flag |= NCF_HOTNEGATIVE; 691 } 692 mtx_unlock(&neglist->nl_lock); 693 mtx_unlock(&ncneg_hot.nl_lock); 694 } 695 696 static void 697 cache_negative_insert(struct namecache *ncp, bool neg_locked) 698 { 699 struct neglist *neglist; 700 701 MPASS(ncp->nc_flag & NCF_NEGATIVE); 702 cache_assert_bucket_locked(ncp, RA_WLOCKED); 703 neglist = NCP2NEGLIST(ncp); 704 if (!neg_locked) { 705 mtx_lock(&neglist->nl_lock); 706 } else { 707 mtx_assert(&neglist->nl_lock, MA_OWNED); 708 } 709 TAILQ_INSERT_TAIL(&neglist->nl_list, ncp, nc_dst); 710 if (!neg_locked) 711 mtx_unlock(&neglist->nl_lock); 712 atomic_add_rel_long(&numneg, 1); 713 } 714 715 static void 716 cache_negative_remove(struct namecache *ncp, bool neg_locked) 717 { 718 struct neglist *neglist; 719 bool hot_locked = false; 720 bool list_locked = false; 721 722 MPASS(ncp->nc_flag & NCF_NEGATIVE); 723 cache_assert_bucket_locked(ncp, RA_WLOCKED); 724 neglist = NCP2NEGLIST(ncp); 725 if (!neg_locked) { 726 if (ncp->nc_flag & NCF_HOTNEGATIVE) { 727 hot_locked = true; 728 mtx_lock(&ncneg_hot.nl_lock); 729 if (!(ncp->nc_flag & NCF_HOTNEGATIVE)) { 730 list_locked = true; 731 mtx_lock(&neglist->nl_lock); 732 } 733 } else { 734 list_locked = true; 735 mtx_lock(&neglist->nl_lock); 736 } 737 } 738 if (ncp->nc_flag & NCF_HOTNEGATIVE) { 739 mtx_assert(&ncneg_hot.nl_lock, MA_OWNED); 740 TAILQ_REMOVE(&ncneg_hot.nl_list, ncp, nc_dst); 741 numhotneg--; 742 } else { 743 mtx_assert(&neglist->nl_lock, MA_OWNED); 744 TAILQ_REMOVE(&neglist->nl_list, ncp, nc_dst); 745 } 746 if (list_locked) 747 mtx_unlock(&neglist->nl_lock); 748 if (hot_locked) 749 mtx_unlock(&ncneg_hot.nl_lock); 750 atomic_subtract_rel_long(&numneg, 1); 751 } 752 753 static void 754 cache_negative_shrink_select(int start, struct namecache **ncpp, 755 struct neglist **neglistpp) 756 { 757 struct neglist *neglist; 758 struct namecache *ncp; 759 int i; 760 761 *ncpp = ncp = NULL; 762 neglist = NULL; 763 764 for (i = start; i < numneglists; i++) { 765 neglist = &neglists[i]; 766 if (TAILQ_FIRST(&neglist->nl_list) == NULL) 767 continue; 768 mtx_lock(&neglist->nl_lock); 769 ncp = TAILQ_FIRST(&neglist->nl_list); 770 if (ncp != NULL) 771 break; 772 mtx_unlock(&neglist->nl_lock); 773 } 774 775 *neglistpp = neglist; 776 *ncpp = ncp; 777 } 778 779 static void 780 cache_negative_zap_one(void) 781 { 782 struct namecache *ncp, *ncp2; 783 struct neglist *neglist; 784 struct mtx *dvlp; 785 struct rwlock *blp; 786 787 if (mtx_owner(&ncneg_shrink_lock) != NULL || 788 !mtx_trylock(&ncneg_shrink_lock)) { 789 counter_u64_add(shrinking_skipped, 1); 790 return; 791 } 792 793 mtx_lock(&ncneg_hot.nl_lock); 794 ncp = TAILQ_FIRST(&ncneg_hot.nl_list); 795 if (ncp != NULL) { 796 neglist = NCP2NEGLIST(ncp); 797 mtx_lock(&neglist->nl_lock); 798 TAILQ_REMOVE(&ncneg_hot.nl_list, ncp, nc_dst); 799 TAILQ_INSERT_TAIL(&neglist->nl_list, ncp, nc_dst); 800 ncp->nc_flag &= ~NCF_HOTNEGATIVE; 801 numhotneg--; 802 mtx_unlock(&neglist->nl_lock); 803 } 804 mtx_unlock(&ncneg_hot.nl_lock); 805 806 cache_negative_shrink_select(shrink_list_turn, &ncp, &neglist); 807 shrink_list_turn++; 808 if (shrink_list_turn == numneglists) 809 shrink_list_turn = 0; 810 if (ncp == NULL && shrink_list_turn == 0) 811 cache_negative_shrink_select(shrink_list_turn, &ncp, &neglist); 812 mtx_unlock(&ncneg_shrink_lock); 813 if (ncp == NULL) 814 return; 815 816 MPASS(ncp->nc_flag & NCF_NEGATIVE); 817 dvlp = VP2VNODELOCK(ncp->nc_dvp); 818 blp = NCP2BUCKETLOCK(ncp); 819 mtx_unlock(&neglist->nl_lock); 820 mtx_lock(dvlp); 821 rw_wlock(blp); 822 mtx_lock(&neglist->nl_lock); 823 ncp2 = TAILQ_FIRST(&neglist->nl_list); 824 if (ncp != ncp2 || dvlp != VP2VNODELOCK(ncp2->nc_dvp) || 825 blp != NCP2BUCKETLOCK(ncp2) || !(ncp2->nc_flag & NCF_NEGATIVE)) { 826 ncp = NULL; 827 } else { 828 SDT_PROBE2(vfs, namecache, shrink_negative, done, ncp->nc_dvp, 829 ncp->nc_name); 830 831 cache_zap_locked(ncp, true); 832 counter_u64_add(numneg_evicted, 1); 833 } 834 mtx_unlock(&neglist->nl_lock); 835 rw_wunlock(blp); 836 mtx_unlock(dvlp); 837 cache_free(ncp); 838 } 839 840 /* 841 * cache_zap_locked(): 842 * 843 * Removes a namecache entry from cache, whether it contains an actual 844 * pointer to a vnode or if it is just a negative cache entry. 845 */ 846 static void 847 cache_zap_locked(struct namecache *ncp, bool neg_locked) 848 { 849 850 if (!(ncp->nc_flag & NCF_NEGATIVE)) 851 cache_assert_vnode_locked(ncp->nc_vp); 852 cache_assert_vnode_locked(ncp->nc_dvp); 853 cache_assert_bucket_locked(ncp, RA_WLOCKED); 854 855 CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp, 856 (ncp->nc_flag & NCF_NEGATIVE) ? NULL : ncp->nc_vp); 857 LIST_REMOVE(ncp, nc_hash); 858 if (!(ncp->nc_flag & NCF_NEGATIVE)) { 859 SDT_PROBE3(vfs, namecache, zap, done, ncp->nc_dvp, 860 ncp->nc_name, ncp->nc_vp); 861 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst); 862 if (ncp == ncp->nc_vp->v_cache_dd) 863 ncp->nc_vp->v_cache_dd = NULL; 864 } else { 865 SDT_PROBE2(vfs, namecache, zap_negative, done, ncp->nc_dvp, 866 ncp->nc_name); 867 cache_negative_remove(ncp, neg_locked); 868 } 869 if (ncp->nc_flag & NCF_ISDOTDOT) { 870 if (ncp == ncp->nc_dvp->v_cache_dd) 871 ncp->nc_dvp->v_cache_dd = NULL; 872 } else { 873 LIST_REMOVE(ncp, nc_src); 874 if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) { 875 ncp->nc_flag |= NCF_DVDROP; 876 atomic_subtract_rel_long(&numcachehv, 1); 877 } 878 } 879 atomic_subtract_rel_long(&numcache, 1); 880 } 881 882 static void 883 cache_zap_negative_locked_vnode_kl(struct namecache *ncp, struct vnode *vp) 884 { 885 struct rwlock *blp; 886 887 MPASS(ncp->nc_dvp == vp); 888 MPASS(ncp->nc_flag & NCF_NEGATIVE); 889 cache_assert_vnode_locked(vp); 890 891 blp = NCP2BUCKETLOCK(ncp); 892 rw_wlock(blp); 893 cache_zap_locked(ncp, false); 894 rw_wunlock(blp); 895 } 896 897 static bool 898 cache_zap_locked_vnode_kl2(struct namecache *ncp, struct vnode *vp, 899 struct mtx **vlpp) 900 { 901 struct mtx *pvlp, *vlp1, *vlp2, *to_unlock; 902 struct rwlock *blp; 903 904 MPASS(vp == ncp->nc_dvp || vp == ncp->nc_vp); 905 cache_assert_vnode_locked(vp); 906 907 if (ncp->nc_flag & NCF_NEGATIVE) { 908 if (*vlpp != NULL) { 909 mtx_unlock(*vlpp); 910 *vlpp = NULL; 911 } 912 cache_zap_negative_locked_vnode_kl(ncp, vp); 913 return (true); 914 } 915 916 pvlp = VP2VNODELOCK(vp); 917 blp = NCP2BUCKETLOCK(ncp); 918 vlp1 = VP2VNODELOCK(ncp->nc_dvp); 919 vlp2 = VP2VNODELOCK(ncp->nc_vp); 920 921 if (*vlpp == vlp1 || *vlpp == vlp2) { 922 to_unlock = *vlpp; 923 *vlpp = NULL; 924 } else { 925 if (*vlpp != NULL) { 926 mtx_unlock(*vlpp); 927 *vlpp = NULL; 928 } 929 cache_sort_vnodes(&vlp1, &vlp2); 930 if (vlp1 == pvlp) { 931 mtx_lock(vlp2); 932 to_unlock = vlp2; 933 } else { 934 if (!mtx_trylock(vlp1)) 935 goto out_relock; 936 to_unlock = vlp1; 937 } 938 } 939 rw_wlock(blp); 940 cache_zap_locked(ncp, false); 941 rw_wunlock(blp); 942 if (to_unlock != NULL) 943 mtx_unlock(to_unlock); 944 return (true); 945 946 out_relock: 947 mtx_unlock(vlp2); 948 mtx_lock(vlp1); 949 mtx_lock(vlp2); 950 MPASS(*vlpp == NULL); 951 *vlpp = vlp1; 952 return (false); 953 } 954 955 static int __noinline 956 cache_zap_locked_vnode(struct namecache *ncp, struct vnode *vp) 957 { 958 struct mtx *pvlp, *vlp1, *vlp2, *to_unlock; 959 struct rwlock *blp; 960 int error = 0; 961 962 MPASS(vp == ncp->nc_dvp || vp == ncp->nc_vp); 963 cache_assert_vnode_locked(vp); 964 965 pvlp = VP2VNODELOCK(vp); 966 if (ncp->nc_flag & NCF_NEGATIVE) { 967 cache_zap_negative_locked_vnode_kl(ncp, vp); 968 goto out; 969 } 970 971 blp = NCP2BUCKETLOCK(ncp); 972 vlp1 = VP2VNODELOCK(ncp->nc_dvp); 973 vlp2 = VP2VNODELOCK(ncp->nc_vp); 974 cache_sort_vnodes(&vlp1, &vlp2); 975 if (vlp1 == pvlp) { 976 mtx_lock(vlp2); 977 to_unlock = vlp2; 978 } else { 979 if (!mtx_trylock(vlp1)) { 980 error = EAGAIN; 981 goto out; 982 } 983 to_unlock = vlp1; 984 } 985 rw_wlock(blp); 986 cache_zap_locked(ncp, false); 987 rw_wunlock(blp); 988 mtx_unlock(to_unlock); 989 out: 990 mtx_unlock(pvlp); 991 return (error); 992 } 993 994 /* 995 * If trylocking failed we can get here. We know enough to take all needed locks 996 * in the right order and re-lookup the entry. 997 */ 998 static int 999 cache_zap_unlocked_bucket(struct namecache *ncp, struct componentname *cnp, 1000 struct vnode *dvp, struct mtx *dvlp, struct mtx *vlp, uint32_t hash, 1001 struct rwlock *blp) 1002 { 1003 struct namecache *rncp; 1004 1005 cache_assert_bucket_locked(ncp, RA_UNLOCKED); 1006 1007 cache_sort_vnodes(&dvlp, &vlp); 1008 cache_lock_vnodes(dvlp, vlp); 1009 rw_wlock(blp); 1010 LIST_FOREACH(rncp, (NCHHASH(hash)), nc_hash) { 1011 if (rncp == ncp && rncp->nc_dvp == dvp && 1012 rncp->nc_nlen == cnp->cn_namelen && 1013 !bcmp(rncp->nc_name, cnp->cn_nameptr, rncp->nc_nlen)) 1014 break; 1015 } 1016 if (rncp != NULL) { 1017 cache_zap_locked(rncp, false); 1018 rw_wunlock(blp); 1019 cache_unlock_vnodes(dvlp, vlp); 1020 counter_u64_add(zap_and_exit_bucket_relock_success, 1); 1021 return (0); 1022 } 1023 1024 rw_wunlock(blp); 1025 cache_unlock_vnodes(dvlp, vlp); 1026 return (EAGAIN); 1027 } 1028 1029 static int __noinline 1030 cache_zap_wlocked_bucket(struct namecache *ncp, struct componentname *cnp, 1031 uint32_t hash, struct rwlock *blp) 1032 { 1033 struct mtx *dvlp, *vlp; 1034 struct vnode *dvp; 1035 1036 cache_assert_bucket_locked(ncp, RA_WLOCKED); 1037 1038 dvlp = VP2VNODELOCK(ncp->nc_dvp); 1039 vlp = NULL; 1040 if (!(ncp->nc_flag & NCF_NEGATIVE)) 1041 vlp = VP2VNODELOCK(ncp->nc_vp); 1042 if (cache_trylock_vnodes(dvlp, vlp) == 0) { 1043 cache_zap_locked(ncp, false); 1044 rw_wunlock(blp); 1045 cache_unlock_vnodes(dvlp, vlp); 1046 return (0); 1047 } 1048 1049 dvp = ncp->nc_dvp; 1050 rw_wunlock(blp); 1051 return (cache_zap_unlocked_bucket(ncp, cnp, dvp, dvlp, vlp, hash, blp)); 1052 } 1053 1054 static int __noinline 1055 cache_zap_rlocked_bucket(struct namecache *ncp, struct componentname *cnp, 1056 uint32_t hash, struct rwlock *blp) 1057 { 1058 struct mtx *dvlp, *vlp; 1059 struct vnode *dvp; 1060 1061 cache_assert_bucket_locked(ncp, RA_RLOCKED); 1062 1063 dvlp = VP2VNODELOCK(ncp->nc_dvp); 1064 vlp = NULL; 1065 if (!(ncp->nc_flag & NCF_NEGATIVE)) 1066 vlp = VP2VNODELOCK(ncp->nc_vp); 1067 if (cache_trylock_vnodes(dvlp, vlp) == 0) { 1068 rw_runlock(blp); 1069 rw_wlock(blp); 1070 cache_zap_locked(ncp, false); 1071 rw_wunlock(blp); 1072 cache_unlock_vnodes(dvlp, vlp); 1073 return (0); 1074 } 1075 1076 dvp = ncp->nc_dvp; 1077 rw_runlock(blp); 1078 return (cache_zap_unlocked_bucket(ncp, cnp, dvp, dvlp, vlp, hash, blp)); 1079 } 1080 1081 static int 1082 cache_zap_wlocked_bucket_kl(struct namecache *ncp, struct rwlock *blp, 1083 struct mtx **vlpp1, struct mtx **vlpp2) 1084 { 1085 struct mtx *dvlp, *vlp; 1086 1087 cache_assert_bucket_locked(ncp, RA_WLOCKED); 1088 1089 dvlp = VP2VNODELOCK(ncp->nc_dvp); 1090 vlp = NULL; 1091 if (!(ncp->nc_flag & NCF_NEGATIVE)) 1092 vlp = VP2VNODELOCK(ncp->nc_vp); 1093 cache_sort_vnodes(&dvlp, &vlp); 1094 1095 if (*vlpp1 == dvlp && *vlpp2 == vlp) { 1096 cache_zap_locked(ncp, false); 1097 cache_unlock_vnodes(dvlp, vlp); 1098 *vlpp1 = NULL; 1099 *vlpp2 = NULL; 1100 return (0); 1101 } 1102 1103 if (*vlpp1 != NULL) 1104 mtx_unlock(*vlpp1); 1105 if (*vlpp2 != NULL) 1106 mtx_unlock(*vlpp2); 1107 *vlpp1 = NULL; 1108 *vlpp2 = NULL; 1109 1110 if (cache_trylock_vnodes(dvlp, vlp) == 0) { 1111 cache_zap_locked(ncp, false); 1112 cache_unlock_vnodes(dvlp, vlp); 1113 return (0); 1114 } 1115 1116 rw_wunlock(blp); 1117 *vlpp1 = dvlp; 1118 *vlpp2 = vlp; 1119 if (*vlpp1 != NULL) 1120 mtx_lock(*vlpp1); 1121 mtx_lock(*vlpp2); 1122 rw_wlock(blp); 1123 return (EAGAIN); 1124 } 1125 1126 static void 1127 cache_lookup_unlock(struct rwlock *blp, struct mtx *vlp) 1128 { 1129 1130 if (blp != NULL) { 1131 rw_runlock(blp); 1132 } else { 1133 mtx_unlock(vlp); 1134 } 1135 } 1136 1137 static int __noinline 1138 cache_lookup_dot(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, 1139 struct timespec *tsp, int *ticksp) 1140 { 1141 int ltype; 1142 1143 *vpp = dvp; 1144 CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .", 1145 dvp, cnp->cn_nameptr); 1146 counter_u64_add(dothits, 1); 1147 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ".", *vpp); 1148 if (tsp != NULL) 1149 timespecclear(tsp); 1150 if (ticksp != NULL) 1151 *ticksp = ticks; 1152 vrefact(*vpp); 1153 /* 1154 * When we lookup "." we still can be asked to lock it 1155 * differently... 1156 */ 1157 ltype = cnp->cn_lkflags & LK_TYPE_MASK; 1158 if (ltype != VOP_ISLOCKED(*vpp)) { 1159 if (ltype == LK_EXCLUSIVE) { 1160 vn_lock(*vpp, LK_UPGRADE | LK_RETRY); 1161 if (VN_IS_DOOMED((*vpp))) { 1162 /* forced unmount */ 1163 vrele(*vpp); 1164 *vpp = NULL; 1165 return (ENOENT); 1166 } 1167 } else 1168 vn_lock(*vpp, LK_DOWNGRADE | LK_RETRY); 1169 } 1170 return (-1); 1171 } 1172 1173 static __noinline int 1174 cache_lookup_nomakeentry(struct vnode *dvp, struct vnode **vpp, 1175 struct componentname *cnp, struct timespec *tsp, int *ticksp) 1176 { 1177 struct namecache *ncp; 1178 struct rwlock *blp; 1179 struct mtx *dvlp, *dvlp2; 1180 uint32_t hash; 1181 int error; 1182 1183 if (cnp->cn_namelen == 2 && 1184 cnp->cn_nameptr[0] == '.' && cnp->cn_nameptr[1] == '.') { 1185 counter_u64_add(dotdothits, 1); 1186 dvlp = VP2VNODELOCK(dvp); 1187 dvlp2 = NULL; 1188 mtx_lock(dvlp); 1189 retry_dotdot: 1190 ncp = dvp->v_cache_dd; 1191 if (ncp == NULL) { 1192 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, 1193 "..", NULL); 1194 mtx_unlock(dvlp); 1195 if (dvlp2 != NULL) 1196 mtx_unlock(dvlp2); 1197 return (0); 1198 } 1199 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) { 1200 if (ncp->nc_dvp != dvp) 1201 panic("dvp %p v_cache_dd %p\n", dvp, ncp); 1202 if (!cache_zap_locked_vnode_kl2(ncp, 1203 dvp, &dvlp2)) 1204 goto retry_dotdot; 1205 MPASS(dvp->v_cache_dd == NULL); 1206 mtx_unlock(dvlp); 1207 if (dvlp2 != NULL) 1208 mtx_unlock(dvlp2); 1209 cache_free(ncp); 1210 } else { 1211 dvp->v_cache_dd = NULL; 1212 mtx_unlock(dvlp); 1213 if (dvlp2 != NULL) 1214 mtx_unlock(dvlp2); 1215 } 1216 return (0); 1217 } 1218 1219 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp); 1220 blp = HASH2BUCKETLOCK(hash); 1221 retry: 1222 if (LIST_EMPTY(NCHHASH(hash))) 1223 goto out_no_entry; 1224 1225 rw_wlock(blp); 1226 1227 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 1228 counter_u64_add(numchecks, 1); 1229 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 1230 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 1231 break; 1232 } 1233 1234 /* We failed to find an entry */ 1235 if (ncp == NULL) { 1236 rw_wunlock(blp); 1237 goto out_no_entry; 1238 } 1239 1240 error = cache_zap_wlocked_bucket(ncp, cnp, hash, blp); 1241 if (__predict_false(error != 0)) { 1242 zap_and_exit_bucket_fail++; 1243 cache_maybe_yield(); 1244 goto retry; 1245 } 1246 counter_u64_add(numposzaps, 1); 1247 cache_free(ncp); 1248 return (0); 1249 out_no_entry: 1250 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr, NULL); 1251 counter_u64_add(nummisszap, 1); 1252 return (0); 1253 } 1254 1255 /** 1256 * Lookup a name in the name cache 1257 * 1258 * # Arguments 1259 * 1260 * - dvp: Parent directory in which to search. 1261 * - vpp: Return argument. Will contain desired vnode on cache hit. 1262 * - cnp: Parameters of the name search. The most interesting bits of 1263 * the cn_flags field have the following meanings: 1264 * - MAKEENTRY: If clear, free an entry from the cache rather than look 1265 * it up. 1266 * - ISDOTDOT: Must be set if and only if cn_nameptr == ".." 1267 * - tsp: Return storage for cache timestamp. On a successful (positive 1268 * or negative) lookup, tsp will be filled with any timespec that 1269 * was stored when this cache entry was created. However, it will 1270 * be clear for "." entries. 1271 * - ticks: Return storage for alternate cache timestamp. On a successful 1272 * (positive or negative) lookup, it will contain the ticks value 1273 * that was current when the cache entry was created, unless cnp 1274 * was ".". 1275 * 1276 * # Returns 1277 * 1278 * - -1: A positive cache hit. vpp will contain the desired vnode. 1279 * - ENOENT: A negative cache hit, or dvp was recycled out from under us due 1280 * to a forced unmount. vpp will not be modified. If the entry 1281 * is a whiteout, then the ISWHITEOUT flag will be set in 1282 * cnp->cn_flags. 1283 * - 0: A cache miss. vpp will not be modified. 1284 * 1285 * # Locking 1286 * 1287 * On a cache hit, vpp will be returned locked and ref'd. If we're looking up 1288 * .., dvp is unlocked. If we're looking up . an extra ref is taken, but the 1289 * lock is not recursively acquired. 1290 */ 1291 int 1292 cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, 1293 struct timespec *tsp, int *ticksp) 1294 { 1295 struct namecache_ts *ncp_ts; 1296 struct namecache *ncp; 1297 struct rwlock *blp; 1298 struct mtx *dvlp; 1299 uint32_t hash; 1300 enum vgetstate vs; 1301 int error, ltype; 1302 1303 #ifdef DEBUG_CACHE 1304 if (__predict_false(!doingcache)) { 1305 cnp->cn_flags &= ~MAKEENTRY; 1306 return (0); 1307 } 1308 #endif 1309 1310 counter_u64_add(numcalls, 1); 1311 1312 if (__predict_false(cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.')) 1313 return (cache_lookup_dot(dvp, vpp, cnp, tsp, ticksp)); 1314 1315 if ((cnp->cn_flags & MAKEENTRY) == 0) 1316 return (cache_lookup_nomakeentry(dvp, vpp, cnp, tsp, ticksp)); 1317 1318 retry: 1319 blp = NULL; 1320 dvlp = NULL; 1321 error = 0; 1322 if (cnp->cn_namelen == 2 && 1323 cnp->cn_nameptr[0] == '.' && cnp->cn_nameptr[1] == '.') { 1324 counter_u64_add(dotdothits, 1); 1325 dvlp = VP2VNODELOCK(dvp); 1326 mtx_lock(dvlp); 1327 ncp = dvp->v_cache_dd; 1328 if (ncp == NULL) { 1329 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, 1330 "..", NULL); 1331 mtx_unlock(dvlp); 1332 return (0); 1333 } 1334 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) { 1335 if (ncp->nc_flag & NCF_NEGATIVE) 1336 *vpp = NULL; 1337 else 1338 *vpp = ncp->nc_vp; 1339 } else 1340 *vpp = ncp->nc_dvp; 1341 /* Return failure if negative entry was found. */ 1342 if (*vpp == NULL) 1343 goto negative_success; 1344 CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..", 1345 dvp, cnp->cn_nameptr, *vpp); 1346 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, "..", 1347 *vpp); 1348 cache_out_ts(ncp, tsp, ticksp); 1349 if ((ncp->nc_flag & (NCF_ISDOTDOT | NCF_DTS)) == 1350 NCF_DTS && tsp != NULL) { 1351 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); 1352 *tsp = ncp_ts->nc_dotdottime; 1353 } 1354 goto success; 1355 } 1356 1357 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp); 1358 blp = HASH2BUCKETLOCK(hash); 1359 rw_rlock(blp); 1360 1361 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 1362 counter_u64_add(numchecks, 1); 1363 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 1364 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 1365 break; 1366 } 1367 1368 /* We failed to find an entry */ 1369 if (__predict_false(ncp == NULL)) { 1370 rw_runlock(blp); 1371 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr, 1372 NULL); 1373 counter_u64_add(nummiss, 1); 1374 return (0); 1375 } 1376 1377 if (ncp->nc_flag & NCF_NEGATIVE) 1378 goto negative_success; 1379 1380 /* We found a "positive" match, return the vnode */ 1381 counter_u64_add(numposhits, 1); 1382 *vpp = ncp->nc_vp; 1383 CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p", 1384 dvp, cnp->cn_nameptr, *vpp, ncp); 1385 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ncp->nc_name, 1386 *vpp); 1387 cache_out_ts(ncp, tsp, ticksp); 1388 success: 1389 /* 1390 * On success we return a locked and ref'd vnode as per the lookup 1391 * protocol. 1392 */ 1393 MPASS(dvp != *vpp); 1394 ltype = 0; /* silence gcc warning */ 1395 if (cnp->cn_flags & ISDOTDOT) { 1396 ltype = VOP_ISLOCKED(dvp); 1397 VOP_UNLOCK(dvp); 1398 } 1399 vs = vget_prep(*vpp); 1400 cache_lookup_unlock(blp, dvlp); 1401 error = vget_finish(*vpp, cnp->cn_lkflags, vs); 1402 if (cnp->cn_flags & ISDOTDOT) { 1403 vn_lock(dvp, ltype | LK_RETRY); 1404 if (VN_IS_DOOMED(dvp)) { 1405 if (error == 0) 1406 vput(*vpp); 1407 *vpp = NULL; 1408 return (ENOENT); 1409 } 1410 } 1411 if (error) { 1412 *vpp = NULL; 1413 goto retry; 1414 } 1415 if ((cnp->cn_flags & ISLASTCN) && 1416 (cnp->cn_lkflags & LK_TYPE_MASK) == LK_EXCLUSIVE) { 1417 ASSERT_VOP_ELOCKED(*vpp, "cache_lookup"); 1418 } 1419 return (-1); 1420 1421 negative_success: 1422 /* We found a negative match, and want to create it, so purge */ 1423 if (cnp->cn_nameiop == CREATE) { 1424 counter_u64_add(numnegzaps, 1); 1425 goto zap_and_exit; 1426 } 1427 1428 counter_u64_add(numneghits, 1); 1429 cache_negative_hit(ncp); 1430 if (ncp->nc_flag & NCF_WHITE) 1431 cnp->cn_flags |= ISWHITEOUT; 1432 SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp, 1433 ncp->nc_name); 1434 cache_out_ts(ncp, tsp, ticksp); 1435 cache_lookup_unlock(blp, dvlp); 1436 return (ENOENT); 1437 1438 zap_and_exit: 1439 if (blp != NULL) 1440 error = cache_zap_rlocked_bucket(ncp, cnp, hash, blp); 1441 else 1442 error = cache_zap_locked_vnode(ncp, dvp); 1443 if (__predict_false(error != 0)) { 1444 zap_and_exit_bucket_fail2++; 1445 cache_maybe_yield(); 1446 goto retry; 1447 } 1448 cache_free(ncp); 1449 return (0); 1450 } 1451 1452 struct celockstate { 1453 struct mtx *vlp[3]; 1454 struct rwlock *blp[2]; 1455 }; 1456 CTASSERT((nitems(((struct celockstate *)0)->vlp) == 3)); 1457 CTASSERT((nitems(((struct celockstate *)0)->blp) == 2)); 1458 1459 static inline void 1460 cache_celockstate_init(struct celockstate *cel) 1461 { 1462 1463 bzero(cel, sizeof(*cel)); 1464 } 1465 1466 static void 1467 cache_lock_vnodes_cel(struct celockstate *cel, struct vnode *vp, 1468 struct vnode *dvp) 1469 { 1470 struct mtx *vlp1, *vlp2; 1471 1472 MPASS(cel->vlp[0] == NULL); 1473 MPASS(cel->vlp[1] == NULL); 1474 MPASS(cel->vlp[2] == NULL); 1475 1476 MPASS(vp != NULL || dvp != NULL); 1477 1478 vlp1 = VP2VNODELOCK(vp); 1479 vlp2 = VP2VNODELOCK(dvp); 1480 cache_sort_vnodes(&vlp1, &vlp2); 1481 1482 if (vlp1 != NULL) { 1483 mtx_lock(vlp1); 1484 cel->vlp[0] = vlp1; 1485 } 1486 mtx_lock(vlp2); 1487 cel->vlp[1] = vlp2; 1488 } 1489 1490 static void 1491 cache_unlock_vnodes_cel(struct celockstate *cel) 1492 { 1493 1494 MPASS(cel->vlp[0] != NULL || cel->vlp[1] != NULL); 1495 1496 if (cel->vlp[0] != NULL) 1497 mtx_unlock(cel->vlp[0]); 1498 if (cel->vlp[1] != NULL) 1499 mtx_unlock(cel->vlp[1]); 1500 if (cel->vlp[2] != NULL) 1501 mtx_unlock(cel->vlp[2]); 1502 } 1503 1504 static bool 1505 cache_lock_vnodes_cel_3(struct celockstate *cel, struct vnode *vp) 1506 { 1507 struct mtx *vlp; 1508 bool ret; 1509 1510 cache_assert_vlp_locked(cel->vlp[0]); 1511 cache_assert_vlp_locked(cel->vlp[1]); 1512 MPASS(cel->vlp[2] == NULL); 1513 1514 MPASS(vp != NULL); 1515 vlp = VP2VNODELOCK(vp); 1516 1517 ret = true; 1518 if (vlp >= cel->vlp[1]) { 1519 mtx_lock(vlp); 1520 } else { 1521 if (mtx_trylock(vlp)) 1522 goto out; 1523 cache_lock_vnodes_cel_3_failures++; 1524 cache_unlock_vnodes_cel(cel); 1525 if (vlp < cel->vlp[0]) { 1526 mtx_lock(vlp); 1527 mtx_lock(cel->vlp[0]); 1528 mtx_lock(cel->vlp[1]); 1529 } else { 1530 if (cel->vlp[0] != NULL) 1531 mtx_lock(cel->vlp[0]); 1532 mtx_lock(vlp); 1533 mtx_lock(cel->vlp[1]); 1534 } 1535 ret = false; 1536 } 1537 out: 1538 cel->vlp[2] = vlp; 1539 return (ret); 1540 } 1541 1542 static void 1543 cache_lock_buckets_cel(struct celockstate *cel, struct rwlock *blp1, 1544 struct rwlock *blp2) 1545 { 1546 1547 MPASS(cel->blp[0] == NULL); 1548 MPASS(cel->blp[1] == NULL); 1549 1550 cache_sort_vnodes(&blp1, &blp2); 1551 1552 if (blp1 != NULL) { 1553 rw_wlock(blp1); 1554 cel->blp[0] = blp1; 1555 } 1556 rw_wlock(blp2); 1557 cel->blp[1] = blp2; 1558 } 1559 1560 static void 1561 cache_unlock_buckets_cel(struct celockstate *cel) 1562 { 1563 1564 if (cel->blp[0] != NULL) 1565 rw_wunlock(cel->blp[0]); 1566 rw_wunlock(cel->blp[1]); 1567 } 1568 1569 /* 1570 * Lock part of the cache affected by the insertion. 1571 * 1572 * This means vnodelocks for dvp, vp and the relevant bucketlock. 1573 * However, insertion can result in removal of an old entry. In this 1574 * case we have an additional vnode and bucketlock pair to lock. If the 1575 * entry is negative, ncelock is locked instead of the vnode. 1576 * 1577 * That is, in the worst case we have to lock 3 vnodes and 2 bucketlocks, while 1578 * preserving the locking order (smaller address first). 1579 */ 1580 static void 1581 cache_enter_lock(struct celockstate *cel, struct vnode *dvp, struct vnode *vp, 1582 uint32_t hash) 1583 { 1584 struct namecache *ncp; 1585 struct rwlock *blps[2]; 1586 1587 blps[0] = HASH2BUCKETLOCK(hash); 1588 for (;;) { 1589 blps[1] = NULL; 1590 cache_lock_vnodes_cel(cel, dvp, vp); 1591 if (vp == NULL || vp->v_type != VDIR) 1592 break; 1593 ncp = vp->v_cache_dd; 1594 if (ncp == NULL) 1595 break; 1596 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 1597 break; 1598 MPASS(ncp->nc_dvp == vp); 1599 blps[1] = NCP2BUCKETLOCK(ncp); 1600 if (ncp->nc_flag & NCF_NEGATIVE) 1601 break; 1602 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp)) 1603 break; 1604 /* 1605 * All vnodes got re-locked. Re-validate the state and if 1606 * nothing changed we are done. Otherwise restart. 1607 */ 1608 if (ncp == vp->v_cache_dd && 1609 (ncp->nc_flag & NCF_ISDOTDOT) != 0 && 1610 blps[1] == NCP2BUCKETLOCK(ncp) && 1611 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2]) 1612 break; 1613 cache_unlock_vnodes_cel(cel); 1614 cel->vlp[0] = NULL; 1615 cel->vlp[1] = NULL; 1616 cel->vlp[2] = NULL; 1617 } 1618 cache_lock_buckets_cel(cel, blps[0], blps[1]); 1619 } 1620 1621 static void 1622 cache_enter_lock_dd(struct celockstate *cel, struct vnode *dvp, struct vnode *vp, 1623 uint32_t hash) 1624 { 1625 struct namecache *ncp; 1626 struct rwlock *blps[2]; 1627 1628 blps[0] = HASH2BUCKETLOCK(hash); 1629 for (;;) { 1630 blps[1] = NULL; 1631 cache_lock_vnodes_cel(cel, dvp, vp); 1632 ncp = dvp->v_cache_dd; 1633 if (ncp == NULL) 1634 break; 1635 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 1636 break; 1637 MPASS(ncp->nc_dvp == dvp); 1638 blps[1] = NCP2BUCKETLOCK(ncp); 1639 if (ncp->nc_flag & NCF_NEGATIVE) 1640 break; 1641 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp)) 1642 break; 1643 if (ncp == dvp->v_cache_dd && 1644 (ncp->nc_flag & NCF_ISDOTDOT) != 0 && 1645 blps[1] == NCP2BUCKETLOCK(ncp) && 1646 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2]) 1647 break; 1648 cache_unlock_vnodes_cel(cel); 1649 cel->vlp[0] = NULL; 1650 cel->vlp[1] = NULL; 1651 cel->vlp[2] = NULL; 1652 } 1653 cache_lock_buckets_cel(cel, blps[0], blps[1]); 1654 } 1655 1656 static void 1657 cache_enter_unlock(struct celockstate *cel) 1658 { 1659 1660 cache_unlock_buckets_cel(cel); 1661 cache_unlock_vnodes_cel(cel); 1662 } 1663 1664 static void __noinline 1665 cache_enter_dotdot_prep(struct vnode *dvp, struct vnode *vp, 1666 struct componentname *cnp) 1667 { 1668 struct celockstate cel; 1669 struct namecache *ncp; 1670 uint32_t hash; 1671 int len; 1672 1673 if (dvp->v_cache_dd == NULL) 1674 return; 1675 len = cnp->cn_namelen; 1676 cache_celockstate_init(&cel); 1677 hash = cache_get_hash(cnp->cn_nameptr, len, dvp); 1678 cache_enter_lock_dd(&cel, dvp, vp, hash); 1679 ncp = dvp->v_cache_dd; 1680 if (ncp != NULL && (ncp->nc_flag & NCF_ISDOTDOT)) { 1681 KASSERT(ncp->nc_dvp == dvp, ("wrong isdotdot parent")); 1682 cache_zap_locked(ncp, false); 1683 } else { 1684 ncp = NULL; 1685 } 1686 dvp->v_cache_dd = NULL; 1687 cache_enter_unlock(&cel); 1688 cache_free(ncp); 1689 } 1690 1691 /* 1692 * Add an entry to the cache. 1693 */ 1694 void 1695 cache_enter_time(struct vnode *dvp, struct vnode *vp, struct componentname *cnp, 1696 struct timespec *tsp, struct timespec *dtsp) 1697 { 1698 struct celockstate cel; 1699 struct namecache *ncp, *n2, *ndd; 1700 struct namecache_ts *ncp_ts, *n2_ts; 1701 struct nchashhead *ncpp; 1702 uint32_t hash; 1703 int flag; 1704 int len; 1705 bool held_dvp; 1706 u_long lnumcache; 1707 1708 CTR3(KTR_VFS, "cache_enter(%p, %p, %s)", dvp, vp, cnp->cn_nameptr); 1709 VNASSERT(vp == NULL || !VN_IS_DOOMED(vp), vp, 1710 ("cache_enter: Adding a doomed vnode")); 1711 VNASSERT(dvp == NULL || !VN_IS_DOOMED(dvp), dvp, 1712 ("cache_enter: Doomed vnode used as src")); 1713 1714 #ifdef DEBUG_CACHE 1715 if (__predict_false(!doingcache)) 1716 return; 1717 #endif 1718 1719 flag = 0; 1720 if (__predict_false(cnp->cn_nameptr[0] == '.')) { 1721 if (cnp->cn_namelen == 1) 1722 return; 1723 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 1724 cache_enter_dotdot_prep(dvp, vp, cnp); 1725 flag = NCF_ISDOTDOT; 1726 } 1727 } 1728 1729 /* 1730 * Avoid blowout in namecache entries. 1731 */ 1732 lnumcache = atomic_fetchadd_long(&numcache, 1) + 1; 1733 if (__predict_false(lnumcache >= ncsize)) { 1734 atomic_add_long(&numcache, -1); 1735 return; 1736 } 1737 1738 cache_celockstate_init(&cel); 1739 ndd = NULL; 1740 ncp_ts = NULL; 1741 1742 held_dvp = false; 1743 if (LIST_EMPTY(&dvp->v_cache_src) && flag != NCF_ISDOTDOT) { 1744 vhold(dvp); 1745 atomic_add_long(&numcachehv, 1); 1746 held_dvp = true; 1747 } 1748 1749 /* 1750 * Calculate the hash key and setup as much of the new 1751 * namecache entry as possible before acquiring the lock. 1752 */ 1753 ncp = cache_alloc(cnp->cn_namelen, tsp != NULL); 1754 ncp->nc_flag = flag; 1755 ncp->nc_vp = vp; 1756 if (vp == NULL) 1757 ncp->nc_flag |= NCF_NEGATIVE; 1758 ncp->nc_dvp = dvp; 1759 if (tsp != NULL) { 1760 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); 1761 ncp_ts->nc_time = *tsp; 1762 ncp_ts->nc_ticks = ticks; 1763 ncp_ts->nc_nc.nc_flag |= NCF_TS; 1764 if (dtsp != NULL) { 1765 ncp_ts->nc_dotdottime = *dtsp; 1766 ncp_ts->nc_nc.nc_flag |= NCF_DTS; 1767 } 1768 } 1769 len = ncp->nc_nlen = cnp->cn_namelen; 1770 hash = cache_get_hash(cnp->cn_nameptr, len, dvp); 1771 strlcpy(ncp->nc_name, cnp->cn_nameptr, len + 1); 1772 cache_enter_lock(&cel, dvp, vp, hash); 1773 1774 /* 1775 * See if this vnode or negative entry is already in the cache 1776 * with this name. This can happen with concurrent lookups of 1777 * the same path name. 1778 */ 1779 ncpp = NCHHASH(hash); 1780 LIST_FOREACH(n2, ncpp, nc_hash) { 1781 if (n2->nc_dvp == dvp && 1782 n2->nc_nlen == cnp->cn_namelen && 1783 !bcmp(n2->nc_name, cnp->cn_nameptr, n2->nc_nlen)) { 1784 if (tsp != NULL) { 1785 KASSERT((n2->nc_flag & NCF_TS) != 0, 1786 ("no NCF_TS")); 1787 n2_ts = __containerof(n2, struct namecache_ts, nc_nc); 1788 n2_ts->nc_time = ncp_ts->nc_time; 1789 n2_ts->nc_ticks = ncp_ts->nc_ticks; 1790 if (dtsp != NULL) { 1791 n2_ts->nc_dotdottime = ncp_ts->nc_dotdottime; 1792 if (ncp->nc_flag & NCF_NEGATIVE) 1793 mtx_lock(&ncneg_hot.nl_lock); 1794 n2_ts->nc_nc.nc_flag |= NCF_DTS; 1795 if (ncp->nc_flag & NCF_NEGATIVE) 1796 mtx_unlock(&ncneg_hot.nl_lock); 1797 } 1798 } 1799 goto out_unlock_free; 1800 } 1801 } 1802 1803 if (flag == NCF_ISDOTDOT) { 1804 /* 1805 * See if we are trying to add .. entry, but some other lookup 1806 * has populated v_cache_dd pointer already. 1807 */ 1808 if (dvp->v_cache_dd != NULL) 1809 goto out_unlock_free; 1810 KASSERT(vp == NULL || vp->v_type == VDIR, 1811 ("wrong vnode type %p", vp)); 1812 dvp->v_cache_dd = ncp; 1813 } 1814 1815 if (vp != NULL) { 1816 if (vp->v_type == VDIR) { 1817 if (flag != NCF_ISDOTDOT) { 1818 /* 1819 * For this case, the cache entry maps both the 1820 * directory name in it and the name ".." for the 1821 * directory's parent. 1822 */ 1823 if ((ndd = vp->v_cache_dd) != NULL) { 1824 if ((ndd->nc_flag & NCF_ISDOTDOT) != 0) 1825 cache_zap_locked(ndd, false); 1826 else 1827 ndd = NULL; 1828 } 1829 vp->v_cache_dd = ncp; 1830 } 1831 } else { 1832 vp->v_cache_dd = NULL; 1833 } 1834 } 1835 1836 if (flag != NCF_ISDOTDOT) { 1837 if (LIST_EMPTY(&dvp->v_cache_src)) { 1838 if (!held_dvp) { 1839 vhold(dvp); 1840 atomic_add_long(&numcachehv, 1); 1841 } 1842 } else { 1843 if (held_dvp) { 1844 /* 1845 * This will not take the interlock as someone 1846 * else already holds the vnode on account of 1847 * the namecache and we hold locks preventing 1848 * this from changing. 1849 */ 1850 vdrop(dvp); 1851 atomic_subtract_long(&numcachehv, 1); 1852 } 1853 } 1854 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); 1855 } 1856 1857 /* 1858 * Insert the new namecache entry into the appropriate chain 1859 * within the cache entries table. 1860 */ 1861 LIST_INSERT_HEAD(ncpp, ncp, nc_hash); 1862 1863 /* 1864 * If the entry is "negative", we place it into the 1865 * "negative" cache queue, otherwise, we place it into the 1866 * destination vnode's cache entries queue. 1867 */ 1868 if (vp != NULL) { 1869 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); 1870 SDT_PROBE3(vfs, namecache, enter, done, dvp, ncp->nc_name, 1871 vp); 1872 } else { 1873 if (cnp->cn_flags & ISWHITEOUT) 1874 ncp->nc_flag |= NCF_WHITE; 1875 cache_negative_insert(ncp, false); 1876 SDT_PROBE2(vfs, namecache, enter_negative, done, dvp, 1877 ncp->nc_name); 1878 } 1879 cache_enter_unlock(&cel); 1880 if (numneg * ncnegfactor > lnumcache) 1881 cache_negative_zap_one(); 1882 cache_free(ndd); 1883 return; 1884 out_unlock_free: 1885 cache_enter_unlock(&cel); 1886 cache_free(ncp); 1887 if (held_dvp) { 1888 vdrop(dvp); 1889 atomic_subtract_long(&numcachehv, 1); 1890 } 1891 return; 1892 } 1893 1894 static u_int 1895 cache_roundup_2(u_int val) 1896 { 1897 u_int res; 1898 1899 for (res = 1; res <= val; res <<= 1) 1900 continue; 1901 1902 return (res); 1903 } 1904 1905 /* 1906 * Name cache initialization, from vfs_init() when we are booting 1907 */ 1908 static void 1909 nchinit(void *dummy __unused) 1910 { 1911 u_int i; 1912 1913 cache_zone_small = uma_zcreate("S VFS Cache", 1914 sizeof(struct namecache) + CACHE_PATH_CUTOFF + 1, 1915 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache), 1916 UMA_ZONE_ZINIT); 1917 cache_zone_small_ts = uma_zcreate("STS VFS Cache", 1918 sizeof(struct namecache_ts) + CACHE_PATH_CUTOFF + 1, 1919 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache_ts), 1920 UMA_ZONE_ZINIT); 1921 cache_zone_large = uma_zcreate("L VFS Cache", 1922 sizeof(struct namecache) + NAME_MAX + 1, 1923 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache), 1924 UMA_ZONE_ZINIT); 1925 cache_zone_large_ts = uma_zcreate("LTS VFS Cache", 1926 sizeof(struct namecache_ts) + NAME_MAX + 1, 1927 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache_ts), 1928 UMA_ZONE_ZINIT); 1929 1930 ncsize = desiredvnodes * ncsizefactor; 1931 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash); 1932 ncbuckethash = cache_roundup_2(mp_ncpus * mp_ncpus) - 1; 1933 if (ncbuckethash < 7) /* arbitrarily chosen to avoid having one lock */ 1934 ncbuckethash = 7; 1935 if (ncbuckethash > nchash) 1936 ncbuckethash = nchash; 1937 bucketlocks = malloc(sizeof(*bucketlocks) * numbucketlocks, M_VFSCACHE, 1938 M_WAITOK | M_ZERO); 1939 for (i = 0; i < numbucketlocks; i++) 1940 rw_init_flags(&bucketlocks[i], "ncbuc", RW_DUPOK | RW_RECURSE); 1941 ncvnodehash = ncbuckethash; 1942 vnodelocks = malloc(sizeof(*vnodelocks) * numvnodelocks, M_VFSCACHE, 1943 M_WAITOK | M_ZERO); 1944 for (i = 0; i < numvnodelocks; i++) 1945 mtx_init(&vnodelocks[i], "ncvn", NULL, MTX_DUPOK | MTX_RECURSE); 1946 ncpurgeminvnodes = numbucketlocks * 2; 1947 1948 ncneghash = 3; 1949 neglists = malloc(sizeof(*neglists) * numneglists, M_VFSCACHE, 1950 M_WAITOK | M_ZERO); 1951 for (i = 0; i < numneglists; i++) { 1952 mtx_init(&neglists[i].nl_lock, "ncnegl", NULL, MTX_DEF); 1953 TAILQ_INIT(&neglists[i].nl_list); 1954 } 1955 mtx_init(&ncneg_hot.nl_lock, "ncneglh", NULL, MTX_DEF); 1956 TAILQ_INIT(&ncneg_hot.nl_list); 1957 1958 mtx_init(&ncneg_shrink_lock, "ncnegs", NULL, MTX_DEF); 1959 1960 numcalls = counter_u64_alloc(M_WAITOK); 1961 dothits = counter_u64_alloc(M_WAITOK); 1962 dotdothits = counter_u64_alloc(M_WAITOK); 1963 numchecks = counter_u64_alloc(M_WAITOK); 1964 nummiss = counter_u64_alloc(M_WAITOK); 1965 nummisszap = counter_u64_alloc(M_WAITOK); 1966 numposzaps = counter_u64_alloc(M_WAITOK); 1967 numposhits = counter_u64_alloc(M_WAITOK); 1968 numnegzaps = counter_u64_alloc(M_WAITOK); 1969 numneghits = counter_u64_alloc(M_WAITOK); 1970 numfullpathcalls = counter_u64_alloc(M_WAITOK); 1971 numfullpathfail1 = counter_u64_alloc(M_WAITOK); 1972 numfullpathfail2 = counter_u64_alloc(M_WAITOK); 1973 numfullpathfail4 = counter_u64_alloc(M_WAITOK); 1974 numfullpathfound = counter_u64_alloc(M_WAITOK); 1975 zap_and_exit_bucket_relock_success = counter_u64_alloc(M_WAITOK); 1976 numneg_evicted = counter_u64_alloc(M_WAITOK); 1977 shrinking_skipped = counter_u64_alloc(M_WAITOK); 1978 } 1979 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL); 1980 1981 void 1982 cache_changesize(u_long newmaxvnodes) 1983 { 1984 struct nchashhead *new_nchashtbl, *old_nchashtbl; 1985 u_long new_nchash, old_nchash; 1986 struct namecache *ncp; 1987 uint32_t hash; 1988 u_long newncsize; 1989 int i; 1990 1991 newncsize = newmaxvnodes * ncsizefactor; 1992 newmaxvnodes = cache_roundup_2(newmaxvnodes * 2); 1993 if (newmaxvnodes < numbucketlocks) 1994 newmaxvnodes = numbucketlocks; 1995 1996 new_nchashtbl = hashinit(newmaxvnodes, M_VFSCACHE, &new_nchash); 1997 /* If same hash table size, nothing to do */ 1998 if (nchash == new_nchash) { 1999 free(new_nchashtbl, M_VFSCACHE); 2000 return; 2001 } 2002 /* 2003 * Move everything from the old hash table to the new table. 2004 * None of the namecache entries in the table can be removed 2005 * because to do so, they have to be removed from the hash table. 2006 */ 2007 cache_lock_all_vnodes(); 2008 cache_lock_all_buckets(); 2009 old_nchashtbl = nchashtbl; 2010 old_nchash = nchash; 2011 nchashtbl = new_nchashtbl; 2012 nchash = new_nchash; 2013 for (i = 0; i <= old_nchash; i++) { 2014 while ((ncp = LIST_FIRST(&old_nchashtbl[i])) != NULL) { 2015 hash = cache_get_hash(ncp->nc_name, ncp->nc_nlen, 2016 ncp->nc_dvp); 2017 LIST_REMOVE(ncp, nc_hash); 2018 LIST_INSERT_HEAD(NCHHASH(hash), ncp, nc_hash); 2019 } 2020 } 2021 ncsize = newncsize; 2022 cache_unlock_all_buckets(); 2023 cache_unlock_all_vnodes(); 2024 free(old_nchashtbl, M_VFSCACHE); 2025 } 2026 2027 /* 2028 * Invalidate all entries from and to a particular vnode. 2029 */ 2030 void 2031 cache_purge(struct vnode *vp) 2032 { 2033 TAILQ_HEAD(, namecache) ncps; 2034 struct namecache *ncp, *nnp; 2035 struct mtx *vlp, *vlp2; 2036 2037 CTR1(KTR_VFS, "cache_purge(%p)", vp); 2038 SDT_PROBE1(vfs, namecache, purge, done, vp); 2039 if (LIST_EMPTY(&vp->v_cache_src) && TAILQ_EMPTY(&vp->v_cache_dst) && 2040 vp->v_cache_dd == NULL) 2041 return; 2042 TAILQ_INIT(&ncps); 2043 vlp = VP2VNODELOCK(vp); 2044 vlp2 = NULL; 2045 mtx_lock(vlp); 2046 retry: 2047 while (!LIST_EMPTY(&vp->v_cache_src)) { 2048 ncp = LIST_FIRST(&vp->v_cache_src); 2049 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 2050 goto retry; 2051 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 2052 } 2053 while (!TAILQ_EMPTY(&vp->v_cache_dst)) { 2054 ncp = TAILQ_FIRST(&vp->v_cache_dst); 2055 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 2056 goto retry; 2057 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 2058 } 2059 ncp = vp->v_cache_dd; 2060 if (ncp != NULL) { 2061 KASSERT(ncp->nc_flag & NCF_ISDOTDOT, 2062 ("lost dotdot link")); 2063 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 2064 goto retry; 2065 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 2066 } 2067 KASSERT(vp->v_cache_dd == NULL, ("incomplete purge")); 2068 mtx_unlock(vlp); 2069 if (vlp2 != NULL) 2070 mtx_unlock(vlp2); 2071 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { 2072 cache_free(ncp); 2073 } 2074 } 2075 2076 /* 2077 * Invalidate all negative entries for a particular directory vnode. 2078 */ 2079 void 2080 cache_purge_negative(struct vnode *vp) 2081 { 2082 TAILQ_HEAD(, namecache) ncps; 2083 struct namecache *ncp, *nnp; 2084 struct mtx *vlp; 2085 2086 CTR1(KTR_VFS, "cache_purge_negative(%p)", vp); 2087 SDT_PROBE1(vfs, namecache, purge_negative, done, vp); 2088 if (LIST_EMPTY(&vp->v_cache_src)) 2089 return; 2090 TAILQ_INIT(&ncps); 2091 vlp = VP2VNODELOCK(vp); 2092 mtx_lock(vlp); 2093 LIST_FOREACH_SAFE(ncp, &vp->v_cache_src, nc_src, nnp) { 2094 if (!(ncp->nc_flag & NCF_NEGATIVE)) 2095 continue; 2096 cache_zap_negative_locked_vnode_kl(ncp, vp); 2097 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 2098 } 2099 mtx_unlock(vlp); 2100 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { 2101 cache_free(ncp); 2102 } 2103 } 2104 2105 /* 2106 * Flush all entries referencing a particular filesystem. 2107 */ 2108 void 2109 cache_purgevfs(struct mount *mp, bool force) 2110 { 2111 TAILQ_HEAD(, namecache) ncps; 2112 struct mtx *vlp1, *vlp2; 2113 struct rwlock *blp; 2114 struct nchashhead *bucket; 2115 struct namecache *ncp, *nnp; 2116 u_long i, j, n_nchash; 2117 int error; 2118 2119 /* Scan hash tables for applicable entries */ 2120 SDT_PROBE1(vfs, namecache, purgevfs, done, mp); 2121 if (!force && mp->mnt_nvnodelistsize <= ncpurgeminvnodes) 2122 return; 2123 TAILQ_INIT(&ncps); 2124 n_nchash = nchash + 1; 2125 vlp1 = vlp2 = NULL; 2126 for (i = 0; i < numbucketlocks; i++) { 2127 blp = (struct rwlock *)&bucketlocks[i]; 2128 rw_wlock(blp); 2129 for (j = i; j < n_nchash; j += numbucketlocks) { 2130 retry: 2131 bucket = &nchashtbl[j]; 2132 LIST_FOREACH_SAFE(ncp, bucket, nc_hash, nnp) { 2133 cache_assert_bucket_locked(ncp, RA_WLOCKED); 2134 if (ncp->nc_dvp->v_mount != mp) 2135 continue; 2136 error = cache_zap_wlocked_bucket_kl(ncp, blp, 2137 &vlp1, &vlp2); 2138 if (error != 0) 2139 goto retry; 2140 TAILQ_INSERT_HEAD(&ncps, ncp, nc_dst); 2141 } 2142 } 2143 rw_wunlock(blp); 2144 if (vlp1 == NULL && vlp2 == NULL) 2145 cache_maybe_yield(); 2146 } 2147 if (vlp1 != NULL) 2148 mtx_unlock(vlp1); 2149 if (vlp2 != NULL) 2150 mtx_unlock(vlp2); 2151 2152 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { 2153 cache_free(ncp); 2154 } 2155 } 2156 2157 /* 2158 * Perform canonical checks and cache lookup and pass on to filesystem 2159 * through the vop_cachedlookup only if needed. 2160 */ 2161 2162 int 2163 vfs_cache_lookup(struct vop_lookup_args *ap) 2164 { 2165 struct vnode *dvp; 2166 int error; 2167 struct vnode **vpp = ap->a_vpp; 2168 struct componentname *cnp = ap->a_cnp; 2169 struct ucred *cred = cnp->cn_cred; 2170 int flags = cnp->cn_flags; 2171 struct thread *td = cnp->cn_thread; 2172 2173 *vpp = NULL; 2174 dvp = ap->a_dvp; 2175 2176 if (dvp->v_type != VDIR) 2177 return (ENOTDIR); 2178 2179 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && 2180 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 2181 return (EROFS); 2182 2183 error = VOP_ACCESS(dvp, VEXEC, cred, td); 2184 if (error) 2185 return (error); 2186 2187 error = cache_lookup(dvp, vpp, cnp, NULL, NULL); 2188 if (error == 0) 2189 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); 2190 if (error == -1) 2191 return (0); 2192 return (error); 2193 } 2194 2195 /* 2196 * XXX All of these sysctls would probably be more productive dead. 2197 */ 2198 static int __read_mostly disablecwd; 2199 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, 2200 "Disable the getcwd syscall"); 2201 2202 /* Implementation of the getcwd syscall. */ 2203 int 2204 sys___getcwd(struct thread *td, struct __getcwd_args *uap) 2205 { 2206 2207 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen, 2208 MAXPATHLEN)); 2209 } 2210 2211 int 2212 kern___getcwd(struct thread *td, char *buf, enum uio_seg bufseg, size_t buflen, 2213 size_t path_max) 2214 { 2215 char *bp, *tmpbuf; 2216 struct filedesc *fdp; 2217 struct vnode *cdir, *rdir; 2218 int error; 2219 2220 if (__predict_false(disablecwd)) 2221 return (ENODEV); 2222 if (__predict_false(buflen < 2)) 2223 return (EINVAL); 2224 if (buflen > path_max) 2225 buflen = path_max; 2226 2227 tmpbuf = malloc(buflen, M_TEMP, M_WAITOK); 2228 fdp = td->td_proc->p_fd; 2229 FILEDESC_SLOCK(fdp); 2230 cdir = fdp->fd_cdir; 2231 vrefact(cdir); 2232 rdir = fdp->fd_rdir; 2233 vrefact(rdir); 2234 FILEDESC_SUNLOCK(fdp); 2235 error = vn_fullpath1(td, cdir, rdir, tmpbuf, &bp, buflen); 2236 vrele(rdir); 2237 vrele(cdir); 2238 2239 if (!error) { 2240 if (bufseg == UIO_SYSSPACE) 2241 bcopy(bp, buf, strlen(bp) + 1); 2242 else 2243 error = copyout(bp, buf, strlen(bp) + 1); 2244 #ifdef KTRACE 2245 if (KTRPOINT(curthread, KTR_NAMEI)) 2246 ktrnamei(bp); 2247 #endif 2248 } 2249 free(tmpbuf, M_TEMP); 2250 return (error); 2251 } 2252 2253 /* 2254 * Thus begins the fullpath magic. 2255 */ 2256 2257 static int __read_mostly disablefullpath; 2258 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0, 2259 "Disable the vn_fullpath function"); 2260 2261 /* 2262 * Retrieve the full filesystem path that correspond to a vnode from the name 2263 * cache (if available) 2264 */ 2265 int 2266 vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf) 2267 { 2268 char *buf; 2269 struct filedesc *fdp; 2270 struct vnode *rdir; 2271 int error; 2272 2273 if (__predict_false(disablefullpath)) 2274 return (ENODEV); 2275 if (__predict_false(vn == NULL)) 2276 return (EINVAL); 2277 2278 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 2279 fdp = td->td_proc->p_fd; 2280 FILEDESC_SLOCK(fdp); 2281 rdir = fdp->fd_rdir; 2282 vrefact(rdir); 2283 FILEDESC_SUNLOCK(fdp); 2284 error = vn_fullpath1(td, vn, rdir, buf, retbuf, MAXPATHLEN); 2285 vrele(rdir); 2286 2287 if (!error) 2288 *freebuf = buf; 2289 else 2290 free(buf, M_TEMP); 2291 return (error); 2292 } 2293 2294 /* 2295 * This function is similar to vn_fullpath, but it attempts to lookup the 2296 * pathname relative to the global root mount point. This is required for the 2297 * auditing sub-system, as audited pathnames must be absolute, relative to the 2298 * global root mount point. 2299 */ 2300 int 2301 vn_fullpath_global(struct thread *td, struct vnode *vn, 2302 char **retbuf, char **freebuf) 2303 { 2304 char *buf; 2305 int error; 2306 2307 if (__predict_false(disablefullpath)) 2308 return (ENODEV); 2309 if (__predict_false(vn == NULL)) 2310 return (EINVAL); 2311 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 2312 error = vn_fullpath1(td, vn, rootvnode, buf, retbuf, MAXPATHLEN); 2313 if (!error) 2314 *freebuf = buf; 2315 else 2316 free(buf, M_TEMP); 2317 return (error); 2318 } 2319 2320 int 2321 vn_vptocnp(struct vnode **vp, struct ucred *cred, char *buf, u_int *buflen) 2322 { 2323 struct vnode *dvp; 2324 struct namecache *ncp; 2325 struct mtx *vlp; 2326 int error; 2327 2328 vlp = VP2VNODELOCK(*vp); 2329 mtx_lock(vlp); 2330 TAILQ_FOREACH(ncp, &((*vp)->v_cache_dst), nc_dst) { 2331 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 2332 break; 2333 } 2334 if (ncp != NULL) { 2335 if (*buflen < ncp->nc_nlen) { 2336 mtx_unlock(vlp); 2337 vrele(*vp); 2338 counter_u64_add(numfullpathfail4, 1); 2339 error = ENOMEM; 2340 SDT_PROBE3(vfs, namecache, fullpath, return, error, 2341 vp, NULL); 2342 return (error); 2343 } 2344 *buflen -= ncp->nc_nlen; 2345 memcpy(buf + *buflen, ncp->nc_name, ncp->nc_nlen); 2346 SDT_PROBE3(vfs, namecache, fullpath, hit, ncp->nc_dvp, 2347 ncp->nc_name, vp); 2348 dvp = *vp; 2349 *vp = ncp->nc_dvp; 2350 vref(*vp); 2351 mtx_unlock(vlp); 2352 vrele(dvp); 2353 return (0); 2354 } 2355 SDT_PROBE1(vfs, namecache, fullpath, miss, vp); 2356 2357 mtx_unlock(vlp); 2358 vn_lock(*vp, LK_SHARED | LK_RETRY); 2359 error = VOP_VPTOCNP(*vp, &dvp, cred, buf, buflen); 2360 vput(*vp); 2361 if (error) { 2362 counter_u64_add(numfullpathfail2, 1); 2363 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); 2364 return (error); 2365 } 2366 2367 *vp = dvp; 2368 if (VN_IS_DOOMED(dvp)) { 2369 /* forced unmount */ 2370 vrele(dvp); 2371 error = ENOENT; 2372 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); 2373 return (error); 2374 } 2375 /* 2376 * *vp has its use count incremented still. 2377 */ 2378 2379 return (0); 2380 } 2381 2382 /* 2383 * The magic behind kern___getcwd() and vn_fullpath(). 2384 */ 2385 static int 2386 vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 2387 char *buf, char **retbuf, u_int buflen) 2388 { 2389 int error, slash_prefixed; 2390 #ifdef KDTRACE_HOOKS 2391 struct vnode *startvp = vp; 2392 #endif 2393 struct vnode *vp1; 2394 2395 buflen--; 2396 buf[buflen] = '\0'; 2397 error = 0; 2398 slash_prefixed = 0; 2399 2400 SDT_PROBE1(vfs, namecache, fullpath, entry, vp); 2401 counter_u64_add(numfullpathcalls, 1); 2402 vref(vp); 2403 if (vp->v_type != VDIR) { 2404 error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen); 2405 if (error) 2406 return (error); 2407 if (buflen == 0) { 2408 vrele(vp); 2409 return (ENOMEM); 2410 } 2411 buf[--buflen] = '/'; 2412 slash_prefixed = 1; 2413 } 2414 while (vp != rdir && vp != rootvnode) { 2415 /* 2416 * The vp vnode must be already fully constructed, 2417 * since it is either found in namecache or obtained 2418 * from VOP_VPTOCNP(). We may test for VV_ROOT safely 2419 * without obtaining the vnode lock. 2420 */ 2421 if ((vp->v_vflag & VV_ROOT) != 0) { 2422 vn_lock(vp, LK_RETRY | LK_SHARED); 2423 2424 /* 2425 * With the vnode locked, check for races with 2426 * unmount, forced or not. Note that we 2427 * already verified that vp is not equal to 2428 * the root vnode, which means that 2429 * mnt_vnodecovered can be NULL only for the 2430 * case of unmount. 2431 */ 2432 if (VN_IS_DOOMED(vp) || 2433 (vp1 = vp->v_mount->mnt_vnodecovered) == NULL || 2434 vp1->v_mountedhere != vp->v_mount) { 2435 vput(vp); 2436 error = ENOENT; 2437 SDT_PROBE3(vfs, namecache, fullpath, return, 2438 error, vp, NULL); 2439 break; 2440 } 2441 2442 vref(vp1); 2443 vput(vp); 2444 vp = vp1; 2445 continue; 2446 } 2447 if (vp->v_type != VDIR) { 2448 vrele(vp); 2449 counter_u64_add(numfullpathfail1, 1); 2450 error = ENOTDIR; 2451 SDT_PROBE3(vfs, namecache, fullpath, return, 2452 error, vp, NULL); 2453 break; 2454 } 2455 error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen); 2456 if (error) 2457 break; 2458 if (buflen == 0) { 2459 vrele(vp); 2460 error = ENOMEM; 2461 SDT_PROBE3(vfs, namecache, fullpath, return, error, 2462 startvp, NULL); 2463 break; 2464 } 2465 buf[--buflen] = '/'; 2466 slash_prefixed = 1; 2467 } 2468 if (error) 2469 return (error); 2470 if (!slash_prefixed) { 2471 if (buflen == 0) { 2472 vrele(vp); 2473 counter_u64_add(numfullpathfail4, 1); 2474 SDT_PROBE3(vfs, namecache, fullpath, return, ENOMEM, 2475 startvp, NULL); 2476 return (ENOMEM); 2477 } 2478 buf[--buflen] = '/'; 2479 } 2480 counter_u64_add(numfullpathfound, 1); 2481 vrele(vp); 2482 2483 SDT_PROBE3(vfs, namecache, fullpath, return, 0, startvp, buf + buflen); 2484 *retbuf = buf + buflen; 2485 return (0); 2486 } 2487 2488 struct vnode * 2489 vn_dir_dd_ino(struct vnode *vp) 2490 { 2491 struct namecache *ncp; 2492 struct vnode *ddvp; 2493 struct mtx *vlp; 2494 enum vgetstate vs; 2495 2496 ASSERT_VOP_LOCKED(vp, "vn_dir_dd_ino"); 2497 vlp = VP2VNODELOCK(vp); 2498 mtx_lock(vlp); 2499 TAILQ_FOREACH(ncp, &(vp->v_cache_dst), nc_dst) { 2500 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) 2501 continue; 2502 ddvp = ncp->nc_dvp; 2503 vs = vget_prep(ddvp); 2504 mtx_unlock(vlp); 2505 if (vget_finish(ddvp, LK_SHARED | LK_NOWAIT, vs)) 2506 return (NULL); 2507 return (ddvp); 2508 } 2509 mtx_unlock(vlp); 2510 return (NULL); 2511 } 2512 2513 int 2514 vn_commname(struct vnode *vp, char *buf, u_int buflen) 2515 { 2516 struct namecache *ncp; 2517 struct mtx *vlp; 2518 int l; 2519 2520 vlp = VP2VNODELOCK(vp); 2521 mtx_lock(vlp); 2522 TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst) 2523 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 2524 break; 2525 if (ncp == NULL) { 2526 mtx_unlock(vlp); 2527 return (ENOENT); 2528 } 2529 l = min(ncp->nc_nlen, buflen - 1); 2530 memcpy(buf, ncp->nc_name, l); 2531 mtx_unlock(vlp); 2532 buf[l] = '\0'; 2533 return (0); 2534 } 2535 2536 /* 2537 * This function updates path string to vnode's full global path 2538 * and checks the size of the new path string against the pathlen argument. 2539 * 2540 * Requires a locked, referenced vnode. 2541 * Vnode is re-locked on success or ENODEV, otherwise unlocked. 2542 * 2543 * If sysctl debug.disablefullpath is set, ENODEV is returned, 2544 * vnode is left locked and path remain untouched. 2545 * 2546 * If vp is a directory, the call to vn_fullpath_global() always succeeds 2547 * because it falls back to the ".." lookup if the namecache lookup fails. 2548 */ 2549 int 2550 vn_path_to_global_path(struct thread *td, struct vnode *vp, char *path, 2551 u_int pathlen) 2552 { 2553 struct nameidata nd; 2554 struct vnode *vp1; 2555 char *rpath, *fbuf; 2556 int error; 2557 2558 ASSERT_VOP_ELOCKED(vp, __func__); 2559 2560 /* Return ENODEV if sysctl debug.disablefullpath==1 */ 2561 if (__predict_false(disablefullpath)) 2562 return (ENODEV); 2563 2564 /* Construct global filesystem path from vp. */ 2565 VOP_UNLOCK(vp); 2566 error = vn_fullpath_global(td, vp, &rpath, &fbuf); 2567 2568 if (error != 0) { 2569 vrele(vp); 2570 return (error); 2571 } 2572 2573 if (strlen(rpath) >= pathlen) { 2574 vrele(vp); 2575 error = ENAMETOOLONG; 2576 goto out; 2577 } 2578 2579 /* 2580 * Re-lookup the vnode by path to detect a possible rename. 2581 * As a side effect, the vnode is relocked. 2582 * If vnode was renamed, return ENOENT. 2583 */ 2584 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1, 2585 UIO_SYSSPACE, path, td); 2586 error = namei(&nd); 2587 if (error != 0) { 2588 vrele(vp); 2589 goto out; 2590 } 2591 NDFREE(&nd, NDF_ONLY_PNBUF); 2592 vp1 = nd.ni_vp; 2593 vrele(vp); 2594 if (vp1 == vp) 2595 strcpy(path, rpath); 2596 else { 2597 vput(vp1); 2598 error = ENOENT; 2599 } 2600 2601 out: 2602 free(fbuf, M_TEMP); 2603 return (error); 2604 } 2605 2606 #ifdef DDB 2607 static void 2608 db_print_vpath(struct vnode *vp) 2609 { 2610 2611 while (vp != NULL) { 2612 db_printf("%p: ", vp); 2613 if (vp == rootvnode) { 2614 db_printf("/"); 2615 vp = NULL; 2616 } else { 2617 if (vp->v_vflag & VV_ROOT) { 2618 db_printf("<mount point>"); 2619 vp = vp->v_mount->mnt_vnodecovered; 2620 } else { 2621 struct namecache *ncp; 2622 char *ncn; 2623 int i; 2624 2625 ncp = TAILQ_FIRST(&vp->v_cache_dst); 2626 if (ncp != NULL) { 2627 ncn = ncp->nc_name; 2628 for (i = 0; i < ncp->nc_nlen; i++) 2629 db_printf("%c", *ncn++); 2630 vp = ncp->nc_dvp; 2631 } else { 2632 vp = NULL; 2633 } 2634 } 2635 } 2636 db_printf("\n"); 2637 } 2638 2639 return; 2640 } 2641 2642 DB_SHOW_COMMAND(vpath, db_show_vpath) 2643 { 2644 struct vnode *vp; 2645 2646 if (!have_addr) { 2647 db_printf("usage: show vpath <struct vnode *>\n"); 2648 return; 2649 } 2650 2651 vp = (struct vnode *)addr; 2652 db_print_vpath(vp); 2653 } 2654 2655 #endif 2656