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 if (!(ncp->nc_flag & NCF_NEGATIVE)) { 855 SDT_PROBE3(vfs, namecache, zap, done, ncp->nc_dvp, 856 ncp->nc_name, ncp->nc_vp); 857 } else { 858 SDT_PROBE3(vfs, namecache, zap_negative, done, ncp->nc_dvp, 859 ncp->nc_name, ncp->nc_neghits); 860 } 861 LIST_REMOVE(ncp, nc_hash); 862 if (!(ncp->nc_flag & NCF_NEGATIVE)) { 863 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst); 864 if (ncp == ncp->nc_vp->v_cache_dd) 865 ncp->nc_vp->v_cache_dd = NULL; 866 } else { 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(&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 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(&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 static int 995 cache_zap_wlocked_bucket(struct namecache *ncp, struct rwlock *blp) 996 { 997 struct mtx *dvlp, *vlp; 998 999 cache_assert_bucket_locked(ncp, RA_WLOCKED); 1000 1001 dvlp = VP2VNODELOCK(ncp->nc_dvp); 1002 vlp = NULL; 1003 if (!(ncp->nc_flag & NCF_NEGATIVE)) 1004 vlp = VP2VNODELOCK(ncp->nc_vp); 1005 if (cache_trylock_vnodes(dvlp, vlp) == 0) { 1006 cache_zap_locked(ncp, false); 1007 rw_wunlock(blp); 1008 cache_unlock_vnodes(dvlp, vlp); 1009 return (0); 1010 } 1011 1012 rw_wunlock(blp); 1013 return (EAGAIN); 1014 } 1015 1016 static int 1017 cache_zap_rlocked_bucket(struct namecache *ncp, struct rwlock *blp) 1018 { 1019 struct mtx *dvlp, *vlp; 1020 1021 cache_assert_bucket_locked(ncp, RA_RLOCKED); 1022 1023 dvlp = VP2VNODELOCK(ncp->nc_dvp); 1024 vlp = NULL; 1025 if (!(ncp->nc_flag & NCF_NEGATIVE)) 1026 vlp = VP2VNODELOCK(ncp->nc_vp); 1027 if (cache_trylock_vnodes(dvlp, vlp) == 0) { 1028 rw_runlock(blp); 1029 rw_wlock(blp); 1030 cache_zap_locked(ncp, false); 1031 rw_wunlock(blp); 1032 cache_unlock_vnodes(dvlp, vlp); 1033 return (0); 1034 } 1035 1036 rw_runlock(blp); 1037 return (EAGAIN); 1038 } 1039 1040 static int 1041 cache_zap_wlocked_bucket_kl(struct namecache *ncp, struct rwlock *blp, 1042 struct mtx **vlpp1, struct mtx **vlpp2) 1043 { 1044 struct mtx *dvlp, *vlp; 1045 1046 cache_assert_bucket_locked(ncp, RA_WLOCKED); 1047 1048 dvlp = VP2VNODELOCK(ncp->nc_dvp); 1049 vlp = NULL; 1050 if (!(ncp->nc_flag & NCF_NEGATIVE)) 1051 vlp = VP2VNODELOCK(ncp->nc_vp); 1052 cache_sort(&dvlp, &vlp); 1053 1054 if (*vlpp1 == dvlp && *vlpp2 == vlp) { 1055 cache_zap_locked(ncp, false); 1056 cache_unlock_vnodes(dvlp, vlp); 1057 *vlpp1 = NULL; 1058 *vlpp2 = NULL; 1059 return (0); 1060 } 1061 1062 if (*vlpp1 != NULL) 1063 mtx_unlock(*vlpp1); 1064 if (*vlpp2 != NULL) 1065 mtx_unlock(*vlpp2); 1066 *vlpp1 = NULL; 1067 *vlpp2 = NULL; 1068 1069 if (cache_trylock_vnodes(dvlp, vlp) == 0) { 1070 cache_zap_locked(ncp, false); 1071 cache_unlock_vnodes(dvlp, vlp); 1072 return (0); 1073 } 1074 1075 rw_wunlock(blp); 1076 *vlpp1 = dvlp; 1077 *vlpp2 = vlp; 1078 if (*vlpp1 != NULL) 1079 mtx_lock(*vlpp1); 1080 mtx_lock(*vlpp2); 1081 rw_wlock(blp); 1082 return (EAGAIN); 1083 } 1084 1085 static void 1086 cache_lookup_unlock(struct rwlock *blp, struct mtx *vlp) 1087 { 1088 1089 if (blp != NULL) { 1090 rw_runlock(blp); 1091 } else { 1092 mtx_unlock(vlp); 1093 } 1094 } 1095 1096 static int __noinline 1097 cache_lookup_dot(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, 1098 struct timespec *tsp, int *ticksp) 1099 { 1100 int ltype; 1101 1102 *vpp = dvp; 1103 CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .", 1104 dvp, cnp->cn_nameptr); 1105 counter_u64_add(dothits, 1); 1106 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ".", *vpp); 1107 if (tsp != NULL) 1108 timespecclear(tsp); 1109 if (ticksp != NULL) 1110 *ticksp = ticks; 1111 vrefact(*vpp); 1112 /* 1113 * When we lookup "." we still can be asked to lock it 1114 * differently... 1115 */ 1116 ltype = cnp->cn_lkflags & LK_TYPE_MASK; 1117 if (ltype != VOP_ISLOCKED(*vpp)) { 1118 if (ltype == LK_EXCLUSIVE) { 1119 vn_lock(*vpp, LK_UPGRADE | LK_RETRY); 1120 if ((*vpp)->v_iflag & VI_DOOMED) { 1121 /* forced unmount */ 1122 vrele(*vpp); 1123 *vpp = NULL; 1124 return (ENOENT); 1125 } 1126 } else 1127 vn_lock(*vpp, LK_DOWNGRADE | LK_RETRY); 1128 } 1129 return (-1); 1130 } 1131 1132 static __noinline int 1133 cache_lookup_nomakeentry(struct vnode *dvp, struct vnode **vpp, 1134 struct componentname *cnp, struct timespec *tsp, int *ticksp) 1135 { 1136 struct namecache *ncp; 1137 struct rwlock *blp; 1138 struct mtx *dvlp, *dvlp2; 1139 uint32_t hash; 1140 int error; 1141 1142 if (cnp->cn_namelen == 2 && 1143 cnp->cn_nameptr[0] == '.' && cnp->cn_nameptr[1] == '.') { 1144 counter_u64_add(dotdothits, 1); 1145 dvlp = VP2VNODELOCK(dvp); 1146 dvlp2 = NULL; 1147 mtx_lock(dvlp); 1148 retry_dotdot: 1149 ncp = dvp->v_cache_dd; 1150 if (ncp == NULL) { 1151 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, 1152 "..", NULL); 1153 mtx_unlock(dvlp); 1154 if (dvlp2 != NULL) 1155 mtx_unlock(dvlp2); 1156 return (0); 1157 } 1158 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) { 1159 if (ncp->nc_dvp != dvp) 1160 panic("dvp %p v_cache_dd %p\n", dvp, ncp); 1161 if (!cache_zap_locked_vnode_kl2(ncp, 1162 dvp, &dvlp2)) 1163 goto retry_dotdot; 1164 MPASS(dvp->v_cache_dd == NULL); 1165 mtx_unlock(dvlp); 1166 if (dvlp2 != NULL) 1167 mtx_unlock(dvlp2); 1168 cache_free(ncp); 1169 } else { 1170 dvp->v_cache_dd = NULL; 1171 mtx_unlock(dvlp); 1172 if (dvlp2 != NULL) 1173 mtx_unlock(dvlp2); 1174 } 1175 return (0); 1176 } 1177 1178 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp); 1179 blp = HASH2BUCKETLOCK(hash); 1180 retry: 1181 if (LIST_EMPTY(NCHHASH(hash))) 1182 goto out_no_entry; 1183 1184 rw_wlock(blp); 1185 1186 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 1187 counter_u64_add(numchecks, 1); 1188 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 1189 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 1190 break; 1191 } 1192 1193 /* We failed to find an entry */ 1194 if (ncp == NULL) { 1195 rw_wunlock(blp); 1196 goto out_no_entry; 1197 } 1198 1199 counter_u64_add(numposzaps, 1); 1200 1201 error = cache_zap_wlocked_bucket(ncp, blp); 1202 if (error != 0) { 1203 zap_and_exit_bucket_fail++; 1204 cache_maybe_yield(); 1205 goto retry; 1206 } 1207 cache_free(ncp); 1208 return (0); 1209 out_no_entry: 1210 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr, NULL); 1211 counter_u64_add(nummisszap, 1); 1212 return (0); 1213 } 1214 1215 /** 1216 * Lookup a name in the name cache 1217 * 1218 * # Arguments 1219 * 1220 * - dvp: Parent directory in which to search. 1221 * - vpp: Return argument. Will contain desired vnode on cache hit. 1222 * - cnp: Parameters of the name search. The most interesting bits of 1223 * the cn_flags field have the following meanings: 1224 * - MAKEENTRY: If clear, free an entry from the cache rather than look 1225 * it up. 1226 * - ISDOTDOT: Must be set if and only if cn_nameptr == ".." 1227 * - tsp: Return storage for cache timestamp. On a successful (positive 1228 * or negative) lookup, tsp will be filled with any timespec that 1229 * was stored when this cache entry was created. However, it will 1230 * be clear for "." entries. 1231 * - ticks: Return storage for alternate cache timestamp. On a successful 1232 * (positive or negative) lookup, it will contain the ticks value 1233 * that was current when the cache entry was created, unless cnp 1234 * was ".". 1235 * 1236 * # Returns 1237 * 1238 * - -1: A positive cache hit. vpp will contain the desired vnode. 1239 * - ENOENT: A negative cache hit, or dvp was recycled out from under us due 1240 * to a forced unmount. vpp will not be modified. If the entry 1241 * is a whiteout, then the ISWHITEOUT flag will be set in 1242 * cnp->cn_flags. 1243 * - 0: A cache miss. vpp will not be modified. 1244 * 1245 * # Locking 1246 * 1247 * On a cache hit, vpp will be returned locked and ref'd. If we're looking up 1248 * .., dvp is unlocked. If we're looking up . an extra ref is taken, but the 1249 * lock is not recursively acquired. 1250 */ 1251 int 1252 cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, 1253 struct timespec *tsp, int *ticksp) 1254 { 1255 struct namecache_ts *ncp_ts; 1256 struct namecache *ncp; 1257 struct rwlock *blp; 1258 struct mtx *dvlp; 1259 uint32_t hash; 1260 int error, ltype; 1261 1262 if (__predict_false(!doingcache)) { 1263 cnp->cn_flags &= ~MAKEENTRY; 1264 return (0); 1265 } 1266 1267 counter_u64_add(numcalls, 1); 1268 1269 if (__predict_false(cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.')) 1270 return (cache_lookup_dot(dvp, vpp, cnp, tsp, ticksp)); 1271 1272 if ((cnp->cn_flags & MAKEENTRY) == 0) 1273 return (cache_lookup_nomakeentry(dvp, vpp, cnp, tsp, ticksp)); 1274 1275 retry: 1276 blp = NULL; 1277 dvlp = NULL; 1278 error = 0; 1279 if (cnp->cn_namelen == 2 && 1280 cnp->cn_nameptr[0] == '.' && cnp->cn_nameptr[1] == '.') { 1281 counter_u64_add(dotdothits, 1); 1282 dvlp = VP2VNODELOCK(dvp); 1283 mtx_lock(dvlp); 1284 ncp = dvp->v_cache_dd; 1285 if (ncp == NULL) { 1286 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, 1287 "..", NULL); 1288 mtx_unlock(dvlp); 1289 return (0); 1290 } 1291 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) { 1292 if (ncp->nc_flag & NCF_NEGATIVE) 1293 *vpp = NULL; 1294 else 1295 *vpp = ncp->nc_vp; 1296 } else 1297 *vpp = ncp->nc_dvp; 1298 /* Return failure if negative entry was found. */ 1299 if (*vpp == NULL) 1300 goto negative_success; 1301 CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..", 1302 dvp, cnp->cn_nameptr, *vpp); 1303 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, "..", 1304 *vpp); 1305 cache_out_ts(ncp, tsp, ticksp); 1306 if ((ncp->nc_flag & (NCF_ISDOTDOT | NCF_DTS)) == 1307 NCF_DTS && tsp != NULL) { 1308 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); 1309 *tsp = ncp_ts->nc_dotdottime; 1310 } 1311 goto success; 1312 } 1313 1314 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp); 1315 blp = HASH2BUCKETLOCK(hash); 1316 rw_rlock(blp); 1317 1318 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 1319 counter_u64_add(numchecks, 1); 1320 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 1321 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 1322 break; 1323 } 1324 1325 /* We failed to find an entry */ 1326 if (ncp == NULL) { 1327 rw_runlock(blp); 1328 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr, 1329 NULL); 1330 counter_u64_add(nummiss, 1); 1331 return (0); 1332 } 1333 1334 /* We found a "positive" match, return the vnode */ 1335 if (!(ncp->nc_flag & NCF_NEGATIVE)) { 1336 counter_u64_add(numposhits, 1); 1337 *vpp = ncp->nc_vp; 1338 CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p", 1339 dvp, cnp->cn_nameptr, *vpp, ncp); 1340 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ncp->nc_name, 1341 *vpp); 1342 cache_out_ts(ncp, tsp, ticksp); 1343 goto success; 1344 } 1345 1346 negative_success: 1347 /* We found a negative match, and want to create it, so purge */ 1348 if (cnp->cn_nameiop == CREATE) { 1349 counter_u64_add(numnegzaps, 1); 1350 goto zap_and_exit; 1351 } 1352 1353 counter_u64_add(numneghits, 1); 1354 cache_negative_hit(ncp); 1355 if (ncp->nc_flag & NCF_WHITE) 1356 cnp->cn_flags |= ISWHITEOUT; 1357 SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp, 1358 ncp->nc_name); 1359 cache_out_ts(ncp, tsp, ticksp); 1360 cache_lookup_unlock(blp, dvlp); 1361 return (ENOENT); 1362 1363 success: 1364 /* 1365 * On success we return a locked and ref'd vnode as per the lookup 1366 * protocol. 1367 */ 1368 MPASS(dvp != *vpp); 1369 ltype = 0; /* silence gcc warning */ 1370 if (cnp->cn_flags & ISDOTDOT) { 1371 ltype = VOP_ISLOCKED(dvp); 1372 VOP_UNLOCK(dvp, 0); 1373 } 1374 vhold(*vpp); 1375 cache_lookup_unlock(blp, dvlp); 1376 error = vget(*vpp, cnp->cn_lkflags | LK_VNHELD, cnp->cn_thread); 1377 if (cnp->cn_flags & ISDOTDOT) { 1378 vn_lock(dvp, ltype | LK_RETRY); 1379 if (dvp->v_iflag & VI_DOOMED) { 1380 if (error == 0) 1381 vput(*vpp); 1382 *vpp = NULL; 1383 return (ENOENT); 1384 } 1385 } 1386 if (error) { 1387 *vpp = NULL; 1388 goto retry; 1389 } 1390 if ((cnp->cn_flags & ISLASTCN) && 1391 (cnp->cn_lkflags & LK_TYPE_MASK) == LK_EXCLUSIVE) { 1392 ASSERT_VOP_ELOCKED(*vpp, "cache_lookup"); 1393 } 1394 return (-1); 1395 1396 zap_and_exit: 1397 if (blp != NULL) 1398 error = cache_zap_rlocked_bucket(ncp, blp); 1399 else 1400 error = cache_zap_locked_vnode(ncp, dvp); 1401 if (error != 0) { 1402 zap_and_exit_bucket_fail++; 1403 cache_maybe_yield(); 1404 goto retry; 1405 } 1406 cache_free(ncp); 1407 return (0); 1408 } 1409 1410 struct celockstate { 1411 struct mtx *vlp[3]; 1412 struct rwlock *blp[2]; 1413 }; 1414 CTASSERT((nitems(((struct celockstate *)0)->vlp) == 3)); 1415 CTASSERT((nitems(((struct celockstate *)0)->blp) == 2)); 1416 1417 static inline void 1418 cache_celockstate_init(struct celockstate *cel) 1419 { 1420 1421 bzero(cel, sizeof(*cel)); 1422 } 1423 1424 static void 1425 cache_lock_vnodes_cel(struct celockstate *cel, struct vnode *vp, 1426 struct vnode *dvp) 1427 { 1428 struct mtx *vlp1, *vlp2; 1429 1430 MPASS(cel->vlp[0] == NULL); 1431 MPASS(cel->vlp[1] == NULL); 1432 MPASS(cel->vlp[2] == NULL); 1433 1434 MPASS(vp != NULL || dvp != NULL); 1435 1436 vlp1 = VP2VNODELOCK(vp); 1437 vlp2 = VP2VNODELOCK(dvp); 1438 cache_sort(&vlp1, &vlp2); 1439 1440 if (vlp1 != NULL) { 1441 mtx_lock(vlp1); 1442 cel->vlp[0] = vlp1; 1443 } 1444 mtx_lock(vlp2); 1445 cel->vlp[1] = vlp2; 1446 } 1447 1448 static void 1449 cache_unlock_vnodes_cel(struct celockstate *cel) 1450 { 1451 1452 MPASS(cel->vlp[0] != NULL || cel->vlp[1] != NULL); 1453 1454 if (cel->vlp[0] != NULL) 1455 mtx_unlock(cel->vlp[0]); 1456 if (cel->vlp[1] != NULL) 1457 mtx_unlock(cel->vlp[1]); 1458 if (cel->vlp[2] != NULL) 1459 mtx_unlock(cel->vlp[2]); 1460 } 1461 1462 static bool 1463 cache_lock_vnodes_cel_3(struct celockstate *cel, struct vnode *vp) 1464 { 1465 struct mtx *vlp; 1466 bool ret; 1467 1468 cache_assert_vlp_locked(cel->vlp[0]); 1469 cache_assert_vlp_locked(cel->vlp[1]); 1470 MPASS(cel->vlp[2] == NULL); 1471 1472 MPASS(vp != NULL); 1473 vlp = VP2VNODELOCK(vp); 1474 1475 ret = true; 1476 if (vlp >= cel->vlp[1]) { 1477 mtx_lock(vlp); 1478 } else { 1479 if (mtx_trylock(vlp)) 1480 goto out; 1481 cache_lock_vnodes_cel_3_failures++; 1482 cache_unlock_vnodes_cel(cel); 1483 if (vlp < cel->vlp[0]) { 1484 mtx_lock(vlp); 1485 mtx_lock(cel->vlp[0]); 1486 mtx_lock(cel->vlp[1]); 1487 } else { 1488 if (cel->vlp[0] != NULL) 1489 mtx_lock(cel->vlp[0]); 1490 mtx_lock(vlp); 1491 mtx_lock(cel->vlp[1]); 1492 } 1493 ret = false; 1494 } 1495 out: 1496 cel->vlp[2] = vlp; 1497 return (ret); 1498 } 1499 1500 static void 1501 cache_lock_buckets_cel(struct celockstate *cel, struct rwlock *blp1, 1502 struct rwlock *blp2) 1503 { 1504 1505 MPASS(cel->blp[0] == NULL); 1506 MPASS(cel->blp[1] == NULL); 1507 1508 cache_sort(&blp1, &blp2); 1509 1510 if (blp1 != NULL) { 1511 rw_wlock(blp1); 1512 cel->blp[0] = blp1; 1513 } 1514 rw_wlock(blp2); 1515 cel->blp[1] = blp2; 1516 } 1517 1518 static void 1519 cache_unlock_buckets_cel(struct celockstate *cel) 1520 { 1521 1522 if (cel->blp[0] != NULL) 1523 rw_wunlock(cel->blp[0]); 1524 rw_wunlock(cel->blp[1]); 1525 } 1526 1527 /* 1528 * Lock part of the cache affected by the insertion. 1529 * 1530 * This means vnodelocks for dvp, vp and the relevant bucketlock. 1531 * However, insertion can result in removal of an old entry. In this 1532 * case we have an additional vnode and bucketlock pair to lock. If the 1533 * entry is negative, ncelock is locked instead of the vnode. 1534 * 1535 * That is, in the worst case we have to lock 3 vnodes and 2 bucketlocks, while 1536 * preserving the locking order (smaller address first). 1537 */ 1538 static void 1539 cache_enter_lock(struct celockstate *cel, struct vnode *dvp, struct vnode *vp, 1540 uint32_t hash) 1541 { 1542 struct namecache *ncp; 1543 struct rwlock *blps[2]; 1544 1545 blps[0] = HASH2BUCKETLOCK(hash); 1546 for (;;) { 1547 blps[1] = NULL; 1548 cache_lock_vnodes_cel(cel, dvp, vp); 1549 if (vp == NULL || vp->v_type != VDIR) 1550 break; 1551 ncp = vp->v_cache_dd; 1552 if (ncp == NULL) 1553 break; 1554 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 1555 break; 1556 MPASS(ncp->nc_dvp == vp); 1557 blps[1] = NCP2BUCKETLOCK(ncp); 1558 if (ncp->nc_flag & NCF_NEGATIVE) 1559 break; 1560 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp)) 1561 break; 1562 /* 1563 * All vnodes got re-locked. Re-validate the state and if 1564 * nothing changed we are done. Otherwise restart. 1565 */ 1566 if (ncp == vp->v_cache_dd && 1567 (ncp->nc_flag & NCF_ISDOTDOT) != 0 && 1568 blps[1] == NCP2BUCKETLOCK(ncp) && 1569 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2]) 1570 break; 1571 cache_unlock_vnodes_cel(cel); 1572 cel->vlp[0] = NULL; 1573 cel->vlp[1] = NULL; 1574 cel->vlp[2] = NULL; 1575 } 1576 cache_lock_buckets_cel(cel, blps[0], blps[1]); 1577 } 1578 1579 static void 1580 cache_enter_lock_dd(struct celockstate *cel, struct vnode *dvp, struct vnode *vp, 1581 uint32_t hash) 1582 { 1583 struct namecache *ncp; 1584 struct rwlock *blps[2]; 1585 1586 blps[0] = HASH2BUCKETLOCK(hash); 1587 for (;;) { 1588 blps[1] = NULL; 1589 cache_lock_vnodes_cel(cel, dvp, vp); 1590 ncp = dvp->v_cache_dd; 1591 if (ncp == NULL) 1592 break; 1593 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 1594 break; 1595 MPASS(ncp->nc_dvp == dvp); 1596 blps[1] = NCP2BUCKETLOCK(ncp); 1597 if (ncp->nc_flag & NCF_NEGATIVE) 1598 break; 1599 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp)) 1600 break; 1601 if (ncp == dvp->v_cache_dd && 1602 (ncp->nc_flag & NCF_ISDOTDOT) != 0 && 1603 blps[1] == NCP2BUCKETLOCK(ncp) && 1604 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2]) 1605 break; 1606 cache_unlock_vnodes_cel(cel); 1607 cel->vlp[0] = NULL; 1608 cel->vlp[1] = NULL; 1609 cel->vlp[2] = NULL; 1610 } 1611 cache_lock_buckets_cel(cel, blps[0], blps[1]); 1612 } 1613 1614 static void 1615 cache_enter_unlock(struct celockstate *cel) 1616 { 1617 1618 cache_unlock_buckets_cel(cel); 1619 cache_unlock_vnodes_cel(cel); 1620 } 1621 1622 /* 1623 * Add an entry to the cache. 1624 */ 1625 void 1626 cache_enter_time(struct vnode *dvp, struct vnode *vp, struct componentname *cnp, 1627 struct timespec *tsp, struct timespec *dtsp) 1628 { 1629 struct celockstate cel; 1630 struct namecache *ncp, *n2, *ndd; 1631 struct namecache_ts *ncp_ts, *n2_ts; 1632 struct nchashhead *ncpp; 1633 struct neglist *neglist; 1634 uint32_t hash; 1635 int flag; 1636 int len; 1637 bool neg_locked; 1638 int lnumcache; 1639 1640 CTR3(KTR_VFS, "cache_enter(%p, %p, %s)", dvp, vp, cnp->cn_nameptr); 1641 VNASSERT(vp == NULL || (vp->v_iflag & VI_DOOMED) == 0, vp, 1642 ("cache_enter: Adding a doomed vnode")); 1643 VNASSERT(dvp == NULL || (dvp->v_iflag & VI_DOOMED) == 0, dvp, 1644 ("cache_enter: Doomed vnode used as src")); 1645 1646 if (__predict_false(!doingcache)) 1647 return; 1648 1649 /* 1650 * Avoid blowout in namecache entries. 1651 */ 1652 if (__predict_false(numcache >= desiredvnodes * ncsizefactor)) 1653 return; 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 lnumcache = atomic_fetchadd_long(&numcache, 1) + 1; 1832 if (numneg * ncnegfactor > lnumcache) 1833 cache_negative_zap_one(); 1834 cache_free(ndd); 1835 return; 1836 out_unlock_free: 1837 cache_enter_unlock(&cel); 1838 cache_free(ncp); 1839 return; 1840 } 1841 1842 static u_int 1843 cache_roundup_2(u_int val) 1844 { 1845 u_int res; 1846 1847 for (res = 1; res <= val; res <<= 1) 1848 continue; 1849 1850 return (res); 1851 } 1852 1853 /* 1854 * Name cache initialization, from vfs_init() when we are booting 1855 */ 1856 static void 1857 nchinit(void *dummy __unused) 1858 { 1859 u_int i; 1860 1861 cache_zone_small = uma_zcreate("S VFS Cache", 1862 sizeof(struct namecache) + CACHE_PATH_CUTOFF + 1, 1863 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache), 1864 UMA_ZONE_ZINIT); 1865 cache_zone_small_ts = uma_zcreate("STS VFS Cache", 1866 sizeof(struct namecache_ts) + CACHE_PATH_CUTOFF + 1, 1867 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache_ts), 1868 UMA_ZONE_ZINIT); 1869 cache_zone_large = uma_zcreate("L VFS Cache", 1870 sizeof(struct namecache) + NAME_MAX + 1, 1871 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache), 1872 UMA_ZONE_ZINIT); 1873 cache_zone_large_ts = uma_zcreate("LTS VFS Cache", 1874 sizeof(struct namecache_ts) + NAME_MAX + 1, 1875 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache_ts), 1876 UMA_ZONE_ZINIT); 1877 1878 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash); 1879 ncbuckethash = cache_roundup_2(mp_ncpus * 64) - 1; 1880 if (ncbuckethash > nchash) 1881 ncbuckethash = nchash; 1882 bucketlocks = malloc(sizeof(*bucketlocks) * numbucketlocks, M_VFSCACHE, 1883 M_WAITOK | M_ZERO); 1884 for (i = 0; i < numbucketlocks; i++) 1885 rw_init_flags(&bucketlocks[i], "ncbuc", RW_DUPOK | RW_RECURSE); 1886 ncvnodehash = cache_roundup_2(mp_ncpus * 64) - 1; 1887 vnodelocks = malloc(sizeof(*vnodelocks) * numvnodelocks, M_VFSCACHE, 1888 M_WAITOK | M_ZERO); 1889 for (i = 0; i < numvnodelocks; i++) 1890 mtx_init(&vnodelocks[i], "ncvn", NULL, MTX_DUPOK | MTX_RECURSE); 1891 ncpurgeminvnodes = numbucketlocks; 1892 1893 ncneghash = 3; 1894 neglists = malloc(sizeof(*neglists) * numneglists, M_VFSCACHE, 1895 M_WAITOK | M_ZERO); 1896 for (i = 0; i < numneglists; i++) { 1897 mtx_init(&neglists[i].nl_lock, "ncnegl", NULL, MTX_DEF); 1898 TAILQ_INIT(&neglists[i].nl_list); 1899 } 1900 mtx_init(&ncneg_hot.nl_lock, "ncneglh", NULL, MTX_DEF); 1901 TAILQ_INIT(&ncneg_hot.nl_list); 1902 1903 mtx_init(&ncneg_shrink_lock, "ncnegs", NULL, MTX_DEF); 1904 1905 numcalls = counter_u64_alloc(M_WAITOK); 1906 dothits = counter_u64_alloc(M_WAITOK); 1907 dotdothits = counter_u64_alloc(M_WAITOK); 1908 numchecks = counter_u64_alloc(M_WAITOK); 1909 nummiss = counter_u64_alloc(M_WAITOK); 1910 nummisszap = counter_u64_alloc(M_WAITOK); 1911 numposzaps = counter_u64_alloc(M_WAITOK); 1912 numposhits = counter_u64_alloc(M_WAITOK); 1913 numnegzaps = counter_u64_alloc(M_WAITOK); 1914 numneghits = counter_u64_alloc(M_WAITOK); 1915 numfullpathcalls = counter_u64_alloc(M_WAITOK); 1916 numfullpathfail1 = counter_u64_alloc(M_WAITOK); 1917 numfullpathfail2 = counter_u64_alloc(M_WAITOK); 1918 numfullpathfail4 = counter_u64_alloc(M_WAITOK); 1919 numfullpathfound = counter_u64_alloc(M_WAITOK); 1920 } 1921 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL); 1922 1923 void 1924 cache_changesize(int newmaxvnodes) 1925 { 1926 struct nchashhead *new_nchashtbl, *old_nchashtbl; 1927 u_long new_nchash, old_nchash; 1928 struct namecache *ncp; 1929 uint32_t hash; 1930 int i; 1931 1932 newmaxvnodes = cache_roundup_2(newmaxvnodes * 2); 1933 if (newmaxvnodes < numbucketlocks) 1934 newmaxvnodes = numbucketlocks; 1935 1936 new_nchashtbl = hashinit(newmaxvnodes, M_VFSCACHE, &new_nchash); 1937 /* If same hash table size, nothing to do */ 1938 if (nchash == new_nchash) { 1939 free(new_nchashtbl, M_VFSCACHE); 1940 return; 1941 } 1942 /* 1943 * Move everything from the old hash table to the new table. 1944 * None of the namecache entries in the table can be removed 1945 * because to do so, they have to be removed from the hash table. 1946 */ 1947 cache_lock_all_vnodes(); 1948 cache_lock_all_buckets(); 1949 old_nchashtbl = nchashtbl; 1950 old_nchash = nchash; 1951 nchashtbl = new_nchashtbl; 1952 nchash = new_nchash; 1953 for (i = 0; i <= old_nchash; i++) { 1954 while ((ncp = LIST_FIRST(&old_nchashtbl[i])) != NULL) { 1955 hash = cache_get_hash(ncp->nc_name, ncp->nc_nlen, 1956 ncp->nc_dvp); 1957 LIST_REMOVE(ncp, nc_hash); 1958 LIST_INSERT_HEAD(NCHHASH(hash), ncp, nc_hash); 1959 } 1960 } 1961 cache_unlock_all_buckets(); 1962 cache_unlock_all_vnodes(); 1963 free(old_nchashtbl, M_VFSCACHE); 1964 } 1965 1966 /* 1967 * Invalidate all entries to a particular vnode. 1968 */ 1969 void 1970 cache_purge(struct vnode *vp) 1971 { 1972 TAILQ_HEAD(, namecache) ncps; 1973 struct namecache *ncp, *nnp; 1974 struct mtx *vlp, *vlp2; 1975 1976 CTR1(KTR_VFS, "cache_purge(%p)", vp); 1977 SDT_PROBE1(vfs, namecache, purge, done, vp); 1978 if (LIST_EMPTY(&vp->v_cache_src) && TAILQ_EMPTY(&vp->v_cache_dst) && 1979 vp->v_cache_dd == NULL) 1980 return; 1981 TAILQ_INIT(&ncps); 1982 vlp = VP2VNODELOCK(vp); 1983 vlp2 = NULL; 1984 mtx_lock(vlp); 1985 retry: 1986 while (!LIST_EMPTY(&vp->v_cache_src)) { 1987 ncp = LIST_FIRST(&vp->v_cache_src); 1988 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 1989 goto retry; 1990 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 1991 } 1992 while (!TAILQ_EMPTY(&vp->v_cache_dst)) { 1993 ncp = TAILQ_FIRST(&vp->v_cache_dst); 1994 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 1995 goto retry; 1996 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 1997 } 1998 ncp = vp->v_cache_dd; 1999 if (ncp != NULL) { 2000 KASSERT(ncp->nc_flag & NCF_ISDOTDOT, 2001 ("lost dotdot link")); 2002 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 2003 goto retry; 2004 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 2005 } 2006 KASSERT(vp->v_cache_dd == NULL, ("incomplete purge")); 2007 mtx_unlock(vlp); 2008 if (vlp2 != NULL) 2009 mtx_unlock(vlp2); 2010 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { 2011 cache_free(ncp); 2012 } 2013 } 2014 2015 /* 2016 * Invalidate all negative entries for a particular directory vnode. 2017 */ 2018 void 2019 cache_purge_negative(struct vnode *vp) 2020 { 2021 TAILQ_HEAD(, namecache) ncps; 2022 struct namecache *ncp, *nnp; 2023 struct mtx *vlp; 2024 2025 CTR1(KTR_VFS, "cache_purge_negative(%p)", vp); 2026 SDT_PROBE1(vfs, namecache, purge_negative, done, vp); 2027 if (LIST_EMPTY(&vp->v_cache_src)) 2028 return; 2029 TAILQ_INIT(&ncps); 2030 vlp = VP2VNODELOCK(vp); 2031 mtx_lock(vlp); 2032 LIST_FOREACH_SAFE(ncp, &vp->v_cache_src, nc_src, nnp) { 2033 if (!(ncp->nc_flag & NCF_NEGATIVE)) 2034 continue; 2035 cache_zap_negative_locked_vnode_kl(ncp, vp); 2036 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 2037 } 2038 mtx_unlock(vlp); 2039 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { 2040 cache_free(ncp); 2041 } 2042 } 2043 2044 /* 2045 * Flush all entries referencing a particular filesystem. 2046 */ 2047 void 2048 cache_purgevfs(struct mount *mp, bool force) 2049 { 2050 TAILQ_HEAD(, namecache) ncps; 2051 struct mtx *vlp1, *vlp2; 2052 struct rwlock *blp; 2053 struct nchashhead *bucket; 2054 struct namecache *ncp, *nnp; 2055 u_long i, j, n_nchash; 2056 int error; 2057 2058 /* Scan hash tables for applicable entries */ 2059 SDT_PROBE1(vfs, namecache, purgevfs, done, mp); 2060 if (!force && mp->mnt_nvnodelistsize <= ncpurgeminvnodes) 2061 return; 2062 TAILQ_INIT(&ncps); 2063 n_nchash = nchash + 1; 2064 vlp1 = vlp2 = NULL; 2065 for (i = 0; i < numbucketlocks; i++) { 2066 blp = (struct rwlock *)&bucketlocks[i]; 2067 rw_wlock(blp); 2068 for (j = i; j < n_nchash; j += numbucketlocks) { 2069 retry: 2070 bucket = &nchashtbl[j]; 2071 LIST_FOREACH_SAFE(ncp, bucket, nc_hash, nnp) { 2072 cache_assert_bucket_locked(ncp, RA_WLOCKED); 2073 if (ncp->nc_dvp->v_mount != mp) 2074 continue; 2075 error = cache_zap_wlocked_bucket_kl(ncp, blp, 2076 &vlp1, &vlp2); 2077 if (error != 0) 2078 goto retry; 2079 TAILQ_INSERT_HEAD(&ncps, ncp, nc_dst); 2080 } 2081 } 2082 rw_wunlock(blp); 2083 if (vlp1 == NULL && vlp2 == NULL) 2084 cache_maybe_yield(); 2085 } 2086 if (vlp1 != NULL) 2087 mtx_unlock(vlp1); 2088 if (vlp2 != NULL) 2089 mtx_unlock(vlp2); 2090 2091 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { 2092 cache_free(ncp); 2093 } 2094 } 2095 2096 /* 2097 * Perform canonical checks and cache lookup and pass on to filesystem 2098 * through the vop_cachedlookup only if needed. 2099 */ 2100 2101 int 2102 vfs_cache_lookup(struct vop_lookup_args *ap) 2103 { 2104 struct vnode *dvp; 2105 int error; 2106 struct vnode **vpp = ap->a_vpp; 2107 struct componentname *cnp = ap->a_cnp; 2108 struct ucred *cred = cnp->cn_cred; 2109 int flags = cnp->cn_flags; 2110 struct thread *td = cnp->cn_thread; 2111 2112 *vpp = NULL; 2113 dvp = ap->a_dvp; 2114 2115 if (dvp->v_type != VDIR) 2116 return (ENOTDIR); 2117 2118 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && 2119 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 2120 return (EROFS); 2121 2122 error = VOP_ACCESS(dvp, VEXEC, cred, td); 2123 if (error) 2124 return (error); 2125 2126 error = cache_lookup(dvp, vpp, cnp, NULL, NULL); 2127 if (error == 0) 2128 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); 2129 if (error == -1) 2130 return (0); 2131 return (error); 2132 } 2133 2134 /* 2135 * XXX All of these sysctls would probably be more productive dead. 2136 */ 2137 static int __read_mostly disablecwd; 2138 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, 2139 "Disable the getcwd syscall"); 2140 2141 /* Implementation of the getcwd syscall. */ 2142 int 2143 sys___getcwd(struct thread *td, struct __getcwd_args *uap) 2144 { 2145 2146 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen, 2147 MAXPATHLEN)); 2148 } 2149 2150 int 2151 kern___getcwd(struct thread *td, char *buf, enum uio_seg bufseg, size_t buflen, 2152 size_t path_max) 2153 { 2154 char *bp, *tmpbuf; 2155 struct filedesc *fdp; 2156 struct vnode *cdir, *rdir; 2157 int error; 2158 2159 if (__predict_false(disablecwd)) 2160 return (ENODEV); 2161 if (__predict_false(buflen < 2)) 2162 return (EINVAL); 2163 if (buflen > path_max) 2164 buflen = path_max; 2165 2166 tmpbuf = malloc(buflen, M_TEMP, M_WAITOK); 2167 fdp = td->td_proc->p_fd; 2168 FILEDESC_SLOCK(fdp); 2169 cdir = fdp->fd_cdir; 2170 vrefact(cdir); 2171 rdir = fdp->fd_rdir; 2172 vrefact(rdir); 2173 FILEDESC_SUNLOCK(fdp); 2174 error = vn_fullpath1(td, cdir, rdir, tmpbuf, &bp, buflen); 2175 vrele(rdir); 2176 vrele(cdir); 2177 2178 if (!error) { 2179 if (bufseg == UIO_SYSSPACE) 2180 bcopy(bp, buf, strlen(bp) + 1); 2181 else 2182 error = copyout(bp, buf, strlen(bp) + 1); 2183 #ifdef KTRACE 2184 if (KTRPOINT(curthread, KTR_NAMEI)) 2185 ktrnamei(bp); 2186 #endif 2187 } 2188 free(tmpbuf, M_TEMP); 2189 return (error); 2190 } 2191 2192 /* 2193 * Thus begins the fullpath magic. 2194 */ 2195 2196 static int __read_mostly disablefullpath; 2197 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0, 2198 "Disable the vn_fullpath function"); 2199 2200 /* 2201 * Retrieve the full filesystem path that correspond to a vnode from the name 2202 * cache (if available) 2203 */ 2204 int 2205 vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf) 2206 { 2207 char *buf; 2208 struct filedesc *fdp; 2209 struct vnode *rdir; 2210 int error; 2211 2212 if (__predict_false(disablefullpath)) 2213 return (ENODEV); 2214 if (__predict_false(vn == NULL)) 2215 return (EINVAL); 2216 2217 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 2218 fdp = td->td_proc->p_fd; 2219 FILEDESC_SLOCK(fdp); 2220 rdir = fdp->fd_rdir; 2221 vrefact(rdir); 2222 FILEDESC_SUNLOCK(fdp); 2223 error = vn_fullpath1(td, vn, rdir, buf, retbuf, MAXPATHLEN); 2224 vrele(rdir); 2225 2226 if (!error) 2227 *freebuf = buf; 2228 else 2229 free(buf, M_TEMP); 2230 return (error); 2231 } 2232 2233 /* 2234 * This function is similar to vn_fullpath, but it attempts to lookup the 2235 * pathname relative to the global root mount point. This is required for the 2236 * auditing sub-system, as audited pathnames must be absolute, relative to the 2237 * global root mount point. 2238 */ 2239 int 2240 vn_fullpath_global(struct thread *td, struct vnode *vn, 2241 char **retbuf, char **freebuf) 2242 { 2243 char *buf; 2244 int error; 2245 2246 if (__predict_false(disablefullpath)) 2247 return (ENODEV); 2248 if (__predict_false(vn == NULL)) 2249 return (EINVAL); 2250 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 2251 error = vn_fullpath1(td, vn, rootvnode, buf, retbuf, MAXPATHLEN); 2252 if (!error) 2253 *freebuf = buf; 2254 else 2255 free(buf, M_TEMP); 2256 return (error); 2257 } 2258 2259 int 2260 vn_vptocnp(struct vnode **vp, struct ucred *cred, char *buf, u_int *buflen) 2261 { 2262 struct vnode *dvp; 2263 struct namecache *ncp; 2264 struct mtx *vlp; 2265 int error; 2266 2267 vlp = VP2VNODELOCK(*vp); 2268 mtx_lock(vlp); 2269 TAILQ_FOREACH(ncp, &((*vp)->v_cache_dst), nc_dst) { 2270 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 2271 break; 2272 } 2273 if (ncp != NULL) { 2274 if (*buflen < ncp->nc_nlen) { 2275 mtx_unlock(vlp); 2276 vrele(*vp); 2277 counter_u64_add(numfullpathfail4, 1); 2278 error = ENOMEM; 2279 SDT_PROBE3(vfs, namecache, fullpath, return, error, 2280 vp, NULL); 2281 return (error); 2282 } 2283 *buflen -= ncp->nc_nlen; 2284 memcpy(buf + *buflen, ncp->nc_name, ncp->nc_nlen); 2285 SDT_PROBE3(vfs, namecache, fullpath, hit, ncp->nc_dvp, 2286 ncp->nc_name, vp); 2287 dvp = *vp; 2288 *vp = ncp->nc_dvp; 2289 vref(*vp); 2290 mtx_unlock(vlp); 2291 vrele(dvp); 2292 return (0); 2293 } 2294 SDT_PROBE1(vfs, namecache, fullpath, miss, vp); 2295 2296 mtx_unlock(vlp); 2297 vn_lock(*vp, LK_SHARED | LK_RETRY); 2298 error = VOP_VPTOCNP(*vp, &dvp, cred, buf, buflen); 2299 vput(*vp); 2300 if (error) { 2301 counter_u64_add(numfullpathfail2, 1); 2302 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); 2303 return (error); 2304 } 2305 2306 *vp = dvp; 2307 if (dvp->v_iflag & VI_DOOMED) { 2308 /* forced unmount */ 2309 vrele(dvp); 2310 error = ENOENT; 2311 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); 2312 return (error); 2313 } 2314 /* 2315 * *vp has its use count incremented still. 2316 */ 2317 2318 return (0); 2319 } 2320 2321 /* 2322 * The magic behind kern___getcwd() and vn_fullpath(). 2323 */ 2324 static int 2325 vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 2326 char *buf, char **retbuf, u_int buflen) 2327 { 2328 int error, slash_prefixed; 2329 #ifdef KDTRACE_HOOKS 2330 struct vnode *startvp = vp; 2331 #endif 2332 struct vnode *vp1; 2333 2334 buflen--; 2335 buf[buflen] = '\0'; 2336 error = 0; 2337 slash_prefixed = 0; 2338 2339 SDT_PROBE1(vfs, namecache, fullpath, entry, vp); 2340 counter_u64_add(numfullpathcalls, 1); 2341 vref(vp); 2342 if (vp->v_type != VDIR) { 2343 error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen); 2344 if (error) 2345 return (error); 2346 if (buflen == 0) { 2347 vrele(vp); 2348 return (ENOMEM); 2349 } 2350 buf[--buflen] = '/'; 2351 slash_prefixed = 1; 2352 } 2353 while (vp != rdir && vp != rootvnode) { 2354 /* 2355 * The vp vnode must be already fully constructed, 2356 * since it is either found in namecache or obtained 2357 * from VOP_VPTOCNP(). We may test for VV_ROOT safely 2358 * without obtaining the vnode lock. 2359 */ 2360 if ((vp->v_vflag & VV_ROOT) != 0) { 2361 vn_lock(vp, LK_RETRY | LK_SHARED); 2362 2363 /* 2364 * With the vnode locked, check for races with 2365 * unmount, forced or not. Note that we 2366 * already verified that vp is not equal to 2367 * the root vnode, which means that 2368 * mnt_vnodecovered can be NULL only for the 2369 * case of unmount. 2370 */ 2371 if ((vp->v_iflag & VI_DOOMED) != 0 || 2372 (vp1 = vp->v_mount->mnt_vnodecovered) == NULL || 2373 vp1->v_mountedhere != vp->v_mount) { 2374 vput(vp); 2375 error = ENOENT; 2376 SDT_PROBE3(vfs, namecache, fullpath, return, 2377 error, vp, NULL); 2378 break; 2379 } 2380 2381 vref(vp1); 2382 vput(vp); 2383 vp = vp1; 2384 continue; 2385 } 2386 if (vp->v_type != VDIR) { 2387 vrele(vp); 2388 counter_u64_add(numfullpathfail1, 1); 2389 error = ENOTDIR; 2390 SDT_PROBE3(vfs, namecache, fullpath, return, 2391 error, vp, NULL); 2392 break; 2393 } 2394 error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen); 2395 if (error) 2396 break; 2397 if (buflen == 0) { 2398 vrele(vp); 2399 error = ENOMEM; 2400 SDT_PROBE3(vfs, namecache, fullpath, return, error, 2401 startvp, NULL); 2402 break; 2403 } 2404 buf[--buflen] = '/'; 2405 slash_prefixed = 1; 2406 } 2407 if (error) 2408 return (error); 2409 if (!slash_prefixed) { 2410 if (buflen == 0) { 2411 vrele(vp); 2412 counter_u64_add(numfullpathfail4, 1); 2413 SDT_PROBE3(vfs, namecache, fullpath, return, ENOMEM, 2414 startvp, NULL); 2415 return (ENOMEM); 2416 } 2417 buf[--buflen] = '/'; 2418 } 2419 counter_u64_add(numfullpathfound, 1); 2420 vrele(vp); 2421 2422 SDT_PROBE3(vfs, namecache, fullpath, return, 0, startvp, buf + buflen); 2423 *retbuf = buf + buflen; 2424 return (0); 2425 } 2426 2427 struct vnode * 2428 vn_dir_dd_ino(struct vnode *vp) 2429 { 2430 struct namecache *ncp; 2431 struct vnode *ddvp; 2432 struct mtx *vlp; 2433 2434 ASSERT_VOP_LOCKED(vp, "vn_dir_dd_ino"); 2435 vlp = VP2VNODELOCK(vp); 2436 mtx_lock(vlp); 2437 TAILQ_FOREACH(ncp, &(vp->v_cache_dst), nc_dst) { 2438 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) 2439 continue; 2440 ddvp = ncp->nc_dvp; 2441 vhold(ddvp); 2442 mtx_unlock(vlp); 2443 if (vget(ddvp, LK_SHARED | LK_NOWAIT | LK_VNHELD, curthread)) 2444 return (NULL); 2445 return (ddvp); 2446 } 2447 mtx_unlock(vlp); 2448 return (NULL); 2449 } 2450 2451 int 2452 vn_commname(struct vnode *vp, char *buf, u_int buflen) 2453 { 2454 struct namecache *ncp; 2455 struct mtx *vlp; 2456 int l; 2457 2458 vlp = VP2VNODELOCK(vp); 2459 mtx_lock(vlp); 2460 TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst) 2461 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 2462 break; 2463 if (ncp == NULL) { 2464 mtx_unlock(vlp); 2465 return (ENOENT); 2466 } 2467 l = min(ncp->nc_nlen, buflen - 1); 2468 memcpy(buf, ncp->nc_name, l); 2469 mtx_unlock(vlp); 2470 buf[l] = '\0'; 2471 return (0); 2472 } 2473 2474 /* 2475 * This function updates path string to vnode's full global path 2476 * and checks the size of the new path string against the pathlen argument. 2477 * 2478 * Requires a locked, referenced vnode. 2479 * Vnode is re-locked on success or ENODEV, otherwise unlocked. 2480 * 2481 * If sysctl debug.disablefullpath is set, ENODEV is returned, 2482 * vnode is left locked and path remain untouched. 2483 * 2484 * If vp is a directory, the call to vn_fullpath_global() always succeeds 2485 * because it falls back to the ".." lookup if the namecache lookup fails. 2486 */ 2487 int 2488 vn_path_to_global_path(struct thread *td, struct vnode *vp, char *path, 2489 u_int pathlen) 2490 { 2491 struct nameidata nd; 2492 struct vnode *vp1; 2493 char *rpath, *fbuf; 2494 int error; 2495 2496 ASSERT_VOP_ELOCKED(vp, __func__); 2497 2498 /* Return ENODEV if sysctl debug.disablefullpath==1 */ 2499 if (__predict_false(disablefullpath)) 2500 return (ENODEV); 2501 2502 /* Construct global filesystem path from vp. */ 2503 VOP_UNLOCK(vp, 0); 2504 error = vn_fullpath_global(td, vp, &rpath, &fbuf); 2505 2506 if (error != 0) { 2507 vrele(vp); 2508 return (error); 2509 } 2510 2511 if (strlen(rpath) >= pathlen) { 2512 vrele(vp); 2513 error = ENAMETOOLONG; 2514 goto out; 2515 } 2516 2517 /* 2518 * Re-lookup the vnode by path to detect a possible rename. 2519 * As a side effect, the vnode is relocked. 2520 * If vnode was renamed, return ENOENT. 2521 */ 2522 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1, 2523 UIO_SYSSPACE, path, td); 2524 error = namei(&nd); 2525 if (error != 0) { 2526 vrele(vp); 2527 goto out; 2528 } 2529 NDFREE(&nd, NDF_ONLY_PNBUF); 2530 vp1 = nd.ni_vp; 2531 vrele(vp); 2532 if (vp1 == vp) 2533 strcpy(path, rpath); 2534 else { 2535 vput(vp1); 2536 error = ENOENT; 2537 } 2538 2539 out: 2540 free(fbuf, M_TEMP); 2541 return (error); 2542 } 2543 2544 #ifdef DDB 2545 static void 2546 db_print_vpath(struct vnode *vp) 2547 { 2548 2549 while (vp != NULL) { 2550 db_printf("%p: ", vp); 2551 if (vp == rootvnode) { 2552 db_printf("/"); 2553 vp = NULL; 2554 } else { 2555 if (vp->v_vflag & VV_ROOT) { 2556 db_printf("<mount point>"); 2557 vp = vp->v_mount->mnt_vnodecovered; 2558 } else { 2559 struct namecache *ncp; 2560 char *ncn; 2561 int i; 2562 2563 ncp = TAILQ_FIRST(&vp->v_cache_dst); 2564 if (ncp != NULL) { 2565 ncn = ncp->nc_name; 2566 for (i = 0; i < ncp->nc_nlen; i++) 2567 db_printf("%c", *ncn++); 2568 vp = ncp->nc_dvp; 2569 } else { 2570 vp = NULL; 2571 } 2572 } 2573 } 2574 db_printf("\n"); 2575 } 2576 2577 return; 2578 } 2579 2580 DB_SHOW_COMMAND(vpath, db_show_vpath) 2581 { 2582 struct vnode *vp; 2583 2584 if (!have_addr) { 2585 db_printf("usage: show vpath <struct vnode *>\n"); 2586 return; 2587 } 2588 2589 vp = (struct vnode *)addr; 2590 db_print_vpath(vp); 2591 } 2592 2593 #endif 2594