Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_cache.c
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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: releng/12.0/sys/kern/vfs_cache.c 335437 2018-06-20 08:34:29Z bz $"); 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 (vp, name) where vp 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 /* 1133 * Lookup an entry in the cache 1134 * 1135 * Lookup is called with dvp pointing to the directory to search, 1136 * cnp pointing to the name of the entry being sought. If the lookup 1137 * succeeds, the vnode is returned in *vpp, and a status of -1 is 1138 * returned. If the lookup determines that the name does not exist 1139 * (negative caching), a status of ENOENT is returned. If the lookup 1140 * fails, a status of zero is returned. If the directory vnode is 1141 * recycled out from under us due to a forced unmount, a status of 1142 * ENOENT is returned. 1143 * 1144 * vpp is locked and ref'd on return. If we're looking up DOTDOT, dvp is 1145 * unlocked. If we're looking up . an extra ref is taken, but the lock is 1146 * not recursively acquired. 1147 */ 1148 1149 static __noinline int 1150 cache_lookup_nomakeentry(struct vnode *dvp, struct vnode **vpp, 1151 struct componentname *cnp, struct timespec *tsp, int *ticksp) 1152 { 1153 struct namecache *ncp; 1154 struct rwlock *blp; 1155 struct mtx *dvlp, *dvlp2; 1156 uint32_t hash; 1157 int error; 1158 1159 if (cnp->cn_namelen == 2 && 1160 cnp->cn_nameptr[0] == '.' && cnp->cn_nameptr[1] == '.') { 1161 counter_u64_add(dotdothits, 1); 1162 dvlp = VP2VNODELOCK(dvp); 1163 dvlp2 = NULL; 1164 mtx_lock(dvlp); 1165 retry_dotdot: 1166 ncp = dvp->v_cache_dd; 1167 if (ncp == NULL) { 1168 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, 1169 "..", NULL); 1170 mtx_unlock(dvlp); 1171 if (dvlp2 != NULL) 1172 mtx_unlock(dvlp2); 1173 return (0); 1174 } 1175 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) { 1176 if (ncp->nc_dvp != dvp) 1177 panic("dvp %p v_cache_dd %p\n", dvp, ncp); 1178 if (!cache_zap_locked_vnode_kl2(ncp, 1179 dvp, &dvlp2)) 1180 goto retry_dotdot; 1181 MPASS(dvp->v_cache_dd == NULL); 1182 mtx_unlock(dvlp); 1183 if (dvlp2 != NULL) 1184 mtx_unlock(dvlp2); 1185 cache_free(ncp); 1186 } else { 1187 dvp->v_cache_dd = NULL; 1188 mtx_unlock(dvlp); 1189 if (dvlp2 != NULL) 1190 mtx_unlock(dvlp2); 1191 } 1192 return (0); 1193 } 1194 1195 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp); 1196 blp = HASH2BUCKETLOCK(hash); 1197 retry: 1198 if (LIST_EMPTY(NCHHASH(hash))) 1199 goto out_no_entry; 1200 1201 rw_wlock(blp); 1202 1203 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 1204 counter_u64_add(numchecks, 1); 1205 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 1206 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 1207 break; 1208 } 1209 1210 /* We failed to find an entry */ 1211 if (ncp == NULL) { 1212 rw_wunlock(blp); 1213 goto out_no_entry; 1214 } 1215 1216 counter_u64_add(numposzaps, 1); 1217 1218 error = cache_zap_wlocked_bucket(ncp, blp); 1219 if (error != 0) { 1220 zap_and_exit_bucket_fail++; 1221 cache_maybe_yield(); 1222 goto retry; 1223 } 1224 cache_free(ncp); 1225 return (0); 1226 out_no_entry: 1227 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr, NULL); 1228 counter_u64_add(nummisszap, 1); 1229 return (0); 1230 } 1231 1232 int 1233 cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, 1234 struct timespec *tsp, int *ticksp) 1235 { 1236 struct namecache_ts *ncp_ts; 1237 struct namecache *ncp; 1238 struct rwlock *blp; 1239 struct mtx *dvlp; 1240 uint32_t hash; 1241 int error, ltype; 1242 1243 if (__predict_false(!doingcache)) { 1244 cnp->cn_flags &= ~MAKEENTRY; 1245 return (0); 1246 } 1247 1248 counter_u64_add(numcalls, 1); 1249 1250 if (__predict_false(cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.')) 1251 return (cache_lookup_dot(dvp, vpp, cnp, tsp, ticksp)); 1252 1253 if ((cnp->cn_flags & MAKEENTRY) == 0) 1254 return (cache_lookup_nomakeentry(dvp, vpp, cnp, tsp, ticksp)); 1255 1256 retry: 1257 blp = NULL; 1258 dvlp = NULL; 1259 error = 0; 1260 if (cnp->cn_namelen == 2 && 1261 cnp->cn_nameptr[0] == '.' && cnp->cn_nameptr[1] == '.') { 1262 counter_u64_add(dotdothits, 1); 1263 dvlp = VP2VNODELOCK(dvp); 1264 mtx_lock(dvlp); 1265 ncp = dvp->v_cache_dd; 1266 if (ncp == NULL) { 1267 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, 1268 "..", NULL); 1269 mtx_unlock(dvlp); 1270 return (0); 1271 } 1272 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) { 1273 if (ncp->nc_flag & NCF_NEGATIVE) 1274 *vpp = NULL; 1275 else 1276 *vpp = ncp->nc_vp; 1277 } else 1278 *vpp = ncp->nc_dvp; 1279 /* Return failure if negative entry was found. */ 1280 if (*vpp == NULL) 1281 goto negative_success; 1282 CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..", 1283 dvp, cnp->cn_nameptr, *vpp); 1284 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, "..", 1285 *vpp); 1286 cache_out_ts(ncp, tsp, ticksp); 1287 if ((ncp->nc_flag & (NCF_ISDOTDOT | NCF_DTS)) == 1288 NCF_DTS && tsp != NULL) { 1289 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); 1290 *tsp = ncp_ts->nc_dotdottime; 1291 } 1292 goto success; 1293 } 1294 1295 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp); 1296 blp = HASH2BUCKETLOCK(hash); 1297 rw_rlock(blp); 1298 1299 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 1300 counter_u64_add(numchecks, 1); 1301 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 1302 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 1303 break; 1304 } 1305 1306 /* We failed to find an entry */ 1307 if (ncp == NULL) { 1308 rw_runlock(blp); 1309 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr, 1310 NULL); 1311 counter_u64_add(nummiss, 1); 1312 return (0); 1313 } 1314 1315 /* We found a "positive" match, return the vnode */ 1316 if (!(ncp->nc_flag & NCF_NEGATIVE)) { 1317 counter_u64_add(numposhits, 1); 1318 *vpp = ncp->nc_vp; 1319 CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p", 1320 dvp, cnp->cn_nameptr, *vpp, ncp); 1321 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ncp->nc_name, 1322 *vpp); 1323 cache_out_ts(ncp, tsp, ticksp); 1324 goto success; 1325 } 1326 1327 negative_success: 1328 /* We found a negative match, and want to create it, so purge */ 1329 if (cnp->cn_nameiop == CREATE) { 1330 counter_u64_add(numnegzaps, 1); 1331 goto zap_and_exit; 1332 } 1333 1334 counter_u64_add(numneghits, 1); 1335 cache_negative_hit(ncp); 1336 if (ncp->nc_flag & NCF_WHITE) 1337 cnp->cn_flags |= ISWHITEOUT; 1338 SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp, 1339 ncp->nc_name); 1340 cache_out_ts(ncp, tsp, ticksp); 1341 cache_lookup_unlock(blp, dvlp); 1342 return (ENOENT); 1343 1344 success: 1345 /* 1346 * On success we return a locked and ref'd vnode as per the lookup 1347 * protocol. 1348 */ 1349 MPASS(dvp != *vpp); 1350 ltype = 0; /* silence gcc warning */ 1351 if (cnp->cn_flags & ISDOTDOT) { 1352 ltype = VOP_ISLOCKED(dvp); 1353 VOP_UNLOCK(dvp, 0); 1354 } 1355 vhold(*vpp); 1356 cache_lookup_unlock(blp, dvlp); 1357 error = vget(*vpp, cnp->cn_lkflags | LK_VNHELD, cnp->cn_thread); 1358 if (cnp->cn_flags & ISDOTDOT) { 1359 vn_lock(dvp, ltype | LK_RETRY); 1360 if (dvp->v_iflag & VI_DOOMED) { 1361 if (error == 0) 1362 vput(*vpp); 1363 *vpp = NULL; 1364 return (ENOENT); 1365 } 1366 } 1367 if (error) { 1368 *vpp = NULL; 1369 goto retry; 1370 } 1371 if ((cnp->cn_flags & ISLASTCN) && 1372 (cnp->cn_lkflags & LK_TYPE_MASK) == LK_EXCLUSIVE) { 1373 ASSERT_VOP_ELOCKED(*vpp, "cache_lookup"); 1374 } 1375 return (-1); 1376 1377 zap_and_exit: 1378 if (blp != NULL) 1379 error = cache_zap_rlocked_bucket(ncp, blp); 1380 else 1381 error = cache_zap_locked_vnode(ncp, dvp); 1382 if (error != 0) { 1383 zap_and_exit_bucket_fail++; 1384 cache_maybe_yield(); 1385 goto retry; 1386 } 1387 cache_free(ncp); 1388 return (0); 1389 } 1390 1391 struct celockstate { 1392 struct mtx *vlp[3]; 1393 struct rwlock *blp[2]; 1394 }; 1395 CTASSERT((nitems(((struct celockstate *)0)->vlp) == 3)); 1396 CTASSERT((nitems(((struct celockstate *)0)->blp) == 2)); 1397 1398 static inline void 1399 cache_celockstate_init(struct celockstate *cel) 1400 { 1401 1402 bzero(cel, sizeof(*cel)); 1403 } 1404 1405 static void 1406 cache_lock_vnodes_cel(struct celockstate *cel, struct vnode *vp, 1407 struct vnode *dvp) 1408 { 1409 struct mtx *vlp1, *vlp2; 1410 1411 MPASS(cel->vlp[0] == NULL); 1412 MPASS(cel->vlp[1] == NULL); 1413 MPASS(cel->vlp[2] == NULL); 1414 1415 MPASS(vp != NULL || dvp != NULL); 1416 1417 vlp1 = VP2VNODELOCK(vp); 1418 vlp2 = VP2VNODELOCK(dvp); 1419 cache_sort(&vlp1, &vlp2); 1420 1421 if (vlp1 != NULL) { 1422 mtx_lock(vlp1); 1423 cel->vlp[0] = vlp1; 1424 } 1425 mtx_lock(vlp2); 1426 cel->vlp[1] = vlp2; 1427 } 1428 1429 static void 1430 cache_unlock_vnodes_cel(struct celockstate *cel) 1431 { 1432 1433 MPASS(cel->vlp[0] != NULL || cel->vlp[1] != NULL); 1434 1435 if (cel->vlp[0] != NULL) 1436 mtx_unlock(cel->vlp[0]); 1437 if (cel->vlp[1] != NULL) 1438 mtx_unlock(cel->vlp[1]); 1439 if (cel->vlp[2] != NULL) 1440 mtx_unlock(cel->vlp[2]); 1441 } 1442 1443 static bool 1444 cache_lock_vnodes_cel_3(struct celockstate *cel, struct vnode *vp) 1445 { 1446 struct mtx *vlp; 1447 bool ret; 1448 1449 cache_assert_vlp_locked(cel->vlp[0]); 1450 cache_assert_vlp_locked(cel->vlp[1]); 1451 MPASS(cel->vlp[2] == NULL); 1452 1453 MPASS(vp != NULL); 1454 vlp = VP2VNODELOCK(vp); 1455 1456 ret = true; 1457 if (vlp >= cel->vlp[1]) { 1458 mtx_lock(vlp); 1459 } else { 1460 if (mtx_trylock(vlp)) 1461 goto out; 1462 cache_lock_vnodes_cel_3_failures++; 1463 cache_unlock_vnodes_cel(cel); 1464 if (vlp < cel->vlp[0]) { 1465 mtx_lock(vlp); 1466 mtx_lock(cel->vlp[0]); 1467 mtx_lock(cel->vlp[1]); 1468 } else { 1469 if (cel->vlp[0] != NULL) 1470 mtx_lock(cel->vlp[0]); 1471 mtx_lock(vlp); 1472 mtx_lock(cel->vlp[1]); 1473 } 1474 ret = false; 1475 } 1476 out: 1477 cel->vlp[2] = vlp; 1478 return (ret); 1479 } 1480 1481 static void 1482 cache_lock_buckets_cel(struct celockstate *cel, struct rwlock *blp1, 1483 struct rwlock *blp2) 1484 { 1485 1486 MPASS(cel->blp[0] == NULL); 1487 MPASS(cel->blp[1] == NULL); 1488 1489 cache_sort(&blp1, &blp2); 1490 1491 if (blp1 != NULL) { 1492 rw_wlock(blp1); 1493 cel->blp[0] = blp1; 1494 } 1495 rw_wlock(blp2); 1496 cel->blp[1] = blp2; 1497 } 1498 1499 static void 1500 cache_unlock_buckets_cel(struct celockstate *cel) 1501 { 1502 1503 if (cel->blp[0] != NULL) 1504 rw_wunlock(cel->blp[0]); 1505 rw_wunlock(cel->blp[1]); 1506 } 1507 1508 /* 1509 * Lock part of the cache affected by the insertion. 1510 * 1511 * This means vnodelocks for dvp, vp and the relevant bucketlock. 1512 * However, insertion can result in removal of an old entry. In this 1513 * case we have an additional vnode and bucketlock pair to lock. If the 1514 * entry is negative, ncelock is locked instead of the vnode. 1515 * 1516 * That is, in the worst case we have to lock 3 vnodes and 2 bucketlocks, while 1517 * preserving the locking order (smaller address first). 1518 */ 1519 static void 1520 cache_enter_lock(struct celockstate *cel, struct vnode *dvp, struct vnode *vp, 1521 uint32_t hash) 1522 { 1523 struct namecache *ncp; 1524 struct rwlock *blps[2]; 1525 1526 blps[0] = HASH2BUCKETLOCK(hash); 1527 for (;;) { 1528 blps[1] = NULL; 1529 cache_lock_vnodes_cel(cel, dvp, vp); 1530 if (vp == NULL || vp->v_type != VDIR) 1531 break; 1532 ncp = vp->v_cache_dd; 1533 if (ncp == NULL) 1534 break; 1535 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 1536 break; 1537 MPASS(ncp->nc_dvp == vp); 1538 blps[1] = NCP2BUCKETLOCK(ncp); 1539 if (ncp->nc_flag & NCF_NEGATIVE) 1540 break; 1541 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp)) 1542 break; 1543 /* 1544 * All vnodes got re-locked. Re-validate the state and if 1545 * nothing changed we are done. Otherwise restart. 1546 */ 1547 if (ncp == vp->v_cache_dd && 1548 (ncp->nc_flag & NCF_ISDOTDOT) != 0 && 1549 blps[1] == NCP2BUCKETLOCK(ncp) && 1550 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2]) 1551 break; 1552 cache_unlock_vnodes_cel(cel); 1553 cel->vlp[0] = NULL; 1554 cel->vlp[1] = NULL; 1555 cel->vlp[2] = NULL; 1556 } 1557 cache_lock_buckets_cel(cel, blps[0], blps[1]); 1558 } 1559 1560 static void 1561 cache_enter_lock_dd(struct celockstate *cel, struct vnode *dvp, struct vnode *vp, 1562 uint32_t hash) 1563 { 1564 struct namecache *ncp; 1565 struct rwlock *blps[2]; 1566 1567 blps[0] = HASH2BUCKETLOCK(hash); 1568 for (;;) { 1569 blps[1] = NULL; 1570 cache_lock_vnodes_cel(cel, dvp, vp); 1571 ncp = dvp->v_cache_dd; 1572 if (ncp == NULL) 1573 break; 1574 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 1575 break; 1576 MPASS(ncp->nc_dvp == dvp); 1577 blps[1] = NCP2BUCKETLOCK(ncp); 1578 if (ncp->nc_flag & NCF_NEGATIVE) 1579 break; 1580 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp)) 1581 break; 1582 if (ncp == dvp->v_cache_dd && 1583 (ncp->nc_flag & NCF_ISDOTDOT) != 0 && 1584 blps[1] == NCP2BUCKETLOCK(ncp) && 1585 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2]) 1586 break; 1587 cache_unlock_vnodes_cel(cel); 1588 cel->vlp[0] = NULL; 1589 cel->vlp[1] = NULL; 1590 cel->vlp[2] = NULL; 1591 } 1592 cache_lock_buckets_cel(cel, blps[0], blps[1]); 1593 } 1594 1595 static void 1596 cache_enter_unlock(struct celockstate *cel) 1597 { 1598 1599 cache_unlock_buckets_cel(cel); 1600 cache_unlock_vnodes_cel(cel); 1601 } 1602 1603 /* 1604 * Add an entry to the cache. 1605 */ 1606 void 1607 cache_enter_time(struct vnode *dvp, struct vnode *vp, struct componentname *cnp, 1608 struct timespec *tsp, struct timespec *dtsp) 1609 { 1610 struct celockstate cel; 1611 struct namecache *ncp, *n2, *ndd; 1612 struct namecache_ts *ncp_ts, *n2_ts; 1613 struct nchashhead *ncpp; 1614 struct neglist *neglist; 1615 uint32_t hash; 1616 int flag; 1617 int len; 1618 bool neg_locked; 1619 int lnumcache; 1620 1621 CTR3(KTR_VFS, "cache_enter(%p, %p, %s)", dvp, vp, cnp->cn_nameptr); 1622 VNASSERT(vp == NULL || (vp->v_iflag & VI_DOOMED) == 0, vp, 1623 ("cache_enter: Adding a doomed vnode")); 1624 VNASSERT(dvp == NULL || (dvp->v_iflag & VI_DOOMED) == 0, dvp, 1625 ("cache_enter: Doomed vnode used as src")); 1626 1627 if (__predict_false(!doingcache)) 1628 return; 1629 1630 /* 1631 * Avoid blowout in namecache entries. 1632 */ 1633 if (__predict_false(numcache >= desiredvnodes * ncsizefactor)) 1634 return; 1635 1636 cache_celockstate_init(&cel); 1637 ndd = NULL; 1638 ncp_ts = NULL; 1639 flag = 0; 1640 if (cnp->cn_nameptr[0] == '.') { 1641 if (cnp->cn_namelen == 1) 1642 return; 1643 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 1644 len = cnp->cn_namelen; 1645 hash = cache_get_hash(cnp->cn_nameptr, len, dvp); 1646 cache_enter_lock_dd(&cel, dvp, vp, hash); 1647 /* 1648 * If dotdot entry already exists, just retarget it 1649 * to new parent vnode, otherwise continue with new 1650 * namecache entry allocation. 1651 */ 1652 if ((ncp = dvp->v_cache_dd) != NULL && 1653 ncp->nc_flag & NCF_ISDOTDOT) { 1654 KASSERT(ncp->nc_dvp == dvp, 1655 ("wrong isdotdot parent")); 1656 neg_locked = false; 1657 if (ncp->nc_flag & NCF_NEGATIVE || vp == NULL) { 1658 neglist = NCP2NEGLIST(ncp); 1659 mtx_lock(&ncneg_hot.nl_lock); 1660 mtx_lock(&neglist->nl_lock); 1661 neg_locked = true; 1662 } 1663 if (!(ncp->nc_flag & NCF_NEGATIVE)) { 1664 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, 1665 ncp, nc_dst); 1666 } else { 1667 cache_negative_remove(ncp, true); 1668 } 1669 if (vp != NULL) { 1670 TAILQ_INSERT_HEAD(&vp->v_cache_dst, 1671 ncp, nc_dst); 1672 ncp->nc_flag &= ~(NCF_NEGATIVE|NCF_HOTNEGATIVE); 1673 } else { 1674 ncp->nc_flag &= ~(NCF_HOTNEGATIVE); 1675 ncp->nc_flag |= NCF_NEGATIVE; 1676 cache_negative_insert(ncp, true); 1677 } 1678 if (neg_locked) { 1679 mtx_unlock(&neglist->nl_lock); 1680 mtx_unlock(&ncneg_hot.nl_lock); 1681 } 1682 ncp->nc_vp = vp; 1683 cache_enter_unlock(&cel); 1684 return; 1685 } 1686 dvp->v_cache_dd = NULL; 1687 cache_enter_unlock(&cel); 1688 cache_celockstate_init(&cel); 1689 SDT_PROBE3(vfs, namecache, enter, done, dvp, "..", vp); 1690 flag = NCF_ISDOTDOT; 1691 } 1692 } 1693 1694 /* 1695 * Calculate the hash key and setup as much of the new 1696 * namecache entry as possible before acquiring the lock. 1697 */ 1698 ncp = cache_alloc(cnp->cn_namelen, tsp != NULL); 1699 ncp->nc_flag = flag; 1700 ncp->nc_vp = vp; 1701 if (vp == NULL) 1702 ncp->nc_flag |= NCF_NEGATIVE; 1703 ncp->nc_dvp = dvp; 1704 if (tsp != NULL) { 1705 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); 1706 ncp_ts->nc_time = *tsp; 1707 ncp_ts->nc_ticks = ticks; 1708 ncp_ts->nc_nc.nc_flag |= NCF_TS; 1709 if (dtsp != NULL) { 1710 ncp_ts->nc_dotdottime = *dtsp; 1711 ncp_ts->nc_nc.nc_flag |= NCF_DTS; 1712 } 1713 } 1714 len = ncp->nc_nlen = cnp->cn_namelen; 1715 hash = cache_get_hash(cnp->cn_nameptr, len, dvp); 1716 strlcpy(ncp->nc_name, cnp->cn_nameptr, len + 1); 1717 cache_enter_lock(&cel, dvp, vp, hash); 1718 1719 /* 1720 * See if this vnode or negative entry is already in the cache 1721 * with this name. This can happen with concurrent lookups of 1722 * the same path name. 1723 */ 1724 ncpp = NCHHASH(hash); 1725 LIST_FOREACH(n2, ncpp, nc_hash) { 1726 if (n2->nc_dvp == dvp && 1727 n2->nc_nlen == cnp->cn_namelen && 1728 !bcmp(n2->nc_name, cnp->cn_nameptr, n2->nc_nlen)) { 1729 if (tsp != NULL) { 1730 KASSERT((n2->nc_flag & NCF_TS) != 0, 1731 ("no NCF_TS")); 1732 n2_ts = __containerof(n2, struct namecache_ts, nc_nc); 1733 n2_ts->nc_time = ncp_ts->nc_time; 1734 n2_ts->nc_ticks = ncp_ts->nc_ticks; 1735 if (dtsp != NULL) { 1736 n2_ts->nc_dotdottime = ncp_ts->nc_dotdottime; 1737 if (ncp->nc_flag & NCF_NEGATIVE) 1738 mtx_lock(&ncneg_hot.nl_lock); 1739 n2_ts->nc_nc.nc_flag |= NCF_DTS; 1740 if (ncp->nc_flag & NCF_NEGATIVE) 1741 mtx_unlock(&ncneg_hot.nl_lock); 1742 } 1743 } 1744 goto out_unlock_free; 1745 } 1746 } 1747 1748 if (flag == NCF_ISDOTDOT) { 1749 /* 1750 * See if we are trying to add .. entry, but some other lookup 1751 * has populated v_cache_dd pointer already. 1752 */ 1753 if (dvp->v_cache_dd != NULL) 1754 goto out_unlock_free; 1755 KASSERT(vp == NULL || vp->v_type == VDIR, 1756 ("wrong vnode type %p", vp)); 1757 dvp->v_cache_dd = ncp; 1758 } 1759 1760 if (vp != NULL) { 1761 if (vp->v_type == VDIR) { 1762 if (flag != NCF_ISDOTDOT) { 1763 /* 1764 * For this case, the cache entry maps both the 1765 * directory name in it and the name ".." for the 1766 * directory's parent. 1767 */ 1768 if ((ndd = vp->v_cache_dd) != NULL) { 1769 if ((ndd->nc_flag & NCF_ISDOTDOT) != 0) 1770 cache_zap_locked(ndd, false); 1771 else 1772 ndd = NULL; 1773 } 1774 vp->v_cache_dd = ncp; 1775 } 1776 } else { 1777 vp->v_cache_dd = NULL; 1778 } 1779 } 1780 1781 if (flag != NCF_ISDOTDOT) { 1782 if (LIST_EMPTY(&dvp->v_cache_src)) { 1783 vhold(dvp); 1784 atomic_add_rel_long(&numcachehv, 1); 1785 } 1786 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); 1787 } 1788 1789 /* 1790 * Insert the new namecache entry into the appropriate chain 1791 * within the cache entries table. 1792 */ 1793 LIST_INSERT_HEAD(ncpp, ncp, nc_hash); 1794 1795 /* 1796 * If the entry is "negative", we place it into the 1797 * "negative" cache queue, otherwise, we place it into the 1798 * destination vnode's cache entries queue. 1799 */ 1800 if (vp != NULL) { 1801 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); 1802 SDT_PROBE3(vfs, namecache, enter, done, dvp, ncp->nc_name, 1803 vp); 1804 } else { 1805 if (cnp->cn_flags & ISWHITEOUT) 1806 ncp->nc_flag |= NCF_WHITE; 1807 cache_negative_insert(ncp, false); 1808 SDT_PROBE2(vfs, namecache, enter_negative, done, dvp, 1809 ncp->nc_name); 1810 } 1811 cache_enter_unlock(&cel); 1812 lnumcache = atomic_fetchadd_long(&numcache, 1) + 1; 1813 if (numneg * ncnegfactor > lnumcache) 1814 cache_negative_zap_one(); 1815 cache_free(ndd); 1816 return; 1817 out_unlock_free: 1818 cache_enter_unlock(&cel); 1819 cache_free(ncp); 1820 return; 1821 } 1822 1823 static u_int 1824 cache_roundup_2(u_int val) 1825 { 1826 u_int res; 1827 1828 for (res = 1; res <= val; res <<= 1) 1829 continue; 1830 1831 return (res); 1832 } 1833 1834 /* 1835 * Name cache initialization, from vfs_init() when we are booting 1836 */ 1837 static void 1838 nchinit(void *dummy __unused) 1839 { 1840 u_int i; 1841 1842 cache_zone_small = uma_zcreate("S VFS Cache", 1843 sizeof(struct namecache) + CACHE_PATH_CUTOFF + 1, 1844 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache), 1845 UMA_ZONE_ZINIT); 1846 cache_zone_small_ts = uma_zcreate("STS VFS Cache", 1847 sizeof(struct namecache_ts) + CACHE_PATH_CUTOFF + 1, 1848 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache_ts), 1849 UMA_ZONE_ZINIT); 1850 cache_zone_large = uma_zcreate("L VFS Cache", 1851 sizeof(struct namecache) + NAME_MAX + 1, 1852 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache), 1853 UMA_ZONE_ZINIT); 1854 cache_zone_large_ts = uma_zcreate("LTS VFS Cache", 1855 sizeof(struct namecache_ts) + NAME_MAX + 1, 1856 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache_ts), 1857 UMA_ZONE_ZINIT); 1858 1859 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash); 1860 ncbuckethash = cache_roundup_2(mp_ncpus * 64) - 1; 1861 if (ncbuckethash > nchash) 1862 ncbuckethash = nchash; 1863 bucketlocks = malloc(sizeof(*bucketlocks) * numbucketlocks, M_VFSCACHE, 1864 M_WAITOK | M_ZERO); 1865 for (i = 0; i < numbucketlocks; i++) 1866 rw_init_flags(&bucketlocks[i], "ncbuc", RW_DUPOK | RW_RECURSE); 1867 ncvnodehash = cache_roundup_2(mp_ncpus * 64) - 1; 1868 vnodelocks = malloc(sizeof(*vnodelocks) * numvnodelocks, M_VFSCACHE, 1869 M_WAITOK | M_ZERO); 1870 for (i = 0; i < numvnodelocks; i++) 1871 mtx_init(&vnodelocks[i], "ncvn", NULL, MTX_DUPOK | MTX_RECURSE); 1872 ncpurgeminvnodes = numbucketlocks; 1873 1874 ncneghash = 3; 1875 neglists = malloc(sizeof(*neglists) * numneglists, M_VFSCACHE, 1876 M_WAITOK | M_ZERO); 1877 for (i = 0; i < numneglists; i++) { 1878 mtx_init(&neglists[i].nl_lock, "ncnegl", NULL, MTX_DEF); 1879 TAILQ_INIT(&neglists[i].nl_list); 1880 } 1881 mtx_init(&ncneg_hot.nl_lock, "ncneglh", NULL, MTX_DEF); 1882 TAILQ_INIT(&ncneg_hot.nl_list); 1883 1884 mtx_init(&ncneg_shrink_lock, "ncnegs", NULL, MTX_DEF); 1885 1886 numcalls = counter_u64_alloc(M_WAITOK); 1887 dothits = counter_u64_alloc(M_WAITOK); 1888 dotdothits = counter_u64_alloc(M_WAITOK); 1889 numchecks = counter_u64_alloc(M_WAITOK); 1890 nummiss = counter_u64_alloc(M_WAITOK); 1891 nummisszap = counter_u64_alloc(M_WAITOK); 1892 numposzaps = counter_u64_alloc(M_WAITOK); 1893 numposhits = counter_u64_alloc(M_WAITOK); 1894 numnegzaps = counter_u64_alloc(M_WAITOK); 1895 numneghits = counter_u64_alloc(M_WAITOK); 1896 numfullpathcalls = counter_u64_alloc(M_WAITOK); 1897 numfullpathfail1 = counter_u64_alloc(M_WAITOK); 1898 numfullpathfail2 = counter_u64_alloc(M_WAITOK); 1899 numfullpathfail4 = counter_u64_alloc(M_WAITOK); 1900 numfullpathfound = counter_u64_alloc(M_WAITOK); 1901 } 1902 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL); 1903 1904 void 1905 cache_changesize(int newmaxvnodes) 1906 { 1907 struct nchashhead *new_nchashtbl, *old_nchashtbl; 1908 u_long new_nchash, old_nchash; 1909 struct namecache *ncp; 1910 uint32_t hash; 1911 int i; 1912 1913 newmaxvnodes = cache_roundup_2(newmaxvnodes * 2); 1914 if (newmaxvnodes < numbucketlocks) 1915 newmaxvnodes = numbucketlocks; 1916 1917 new_nchashtbl = hashinit(newmaxvnodes, M_VFSCACHE, &new_nchash); 1918 /* If same hash table size, nothing to do */ 1919 if (nchash == new_nchash) { 1920 free(new_nchashtbl, M_VFSCACHE); 1921 return; 1922 } 1923 /* 1924 * Move everything from the old hash table to the new table. 1925 * None of the namecache entries in the table can be removed 1926 * because to do so, they have to be removed from the hash table. 1927 */ 1928 cache_lock_all_vnodes(); 1929 cache_lock_all_buckets(); 1930 old_nchashtbl = nchashtbl; 1931 old_nchash = nchash; 1932 nchashtbl = new_nchashtbl; 1933 nchash = new_nchash; 1934 for (i = 0; i <= old_nchash; i++) { 1935 while ((ncp = LIST_FIRST(&old_nchashtbl[i])) != NULL) { 1936 hash = cache_get_hash(ncp->nc_name, ncp->nc_nlen, 1937 ncp->nc_dvp); 1938 LIST_REMOVE(ncp, nc_hash); 1939 LIST_INSERT_HEAD(NCHHASH(hash), ncp, nc_hash); 1940 } 1941 } 1942 cache_unlock_all_buckets(); 1943 cache_unlock_all_vnodes(); 1944 free(old_nchashtbl, M_VFSCACHE); 1945 } 1946 1947 /* 1948 * Invalidate all entries to a particular vnode. 1949 */ 1950 void 1951 cache_purge(struct vnode *vp) 1952 { 1953 TAILQ_HEAD(, namecache) ncps; 1954 struct namecache *ncp, *nnp; 1955 struct mtx *vlp, *vlp2; 1956 1957 CTR1(KTR_VFS, "cache_purge(%p)", vp); 1958 SDT_PROBE1(vfs, namecache, purge, done, vp); 1959 if (LIST_EMPTY(&vp->v_cache_src) && TAILQ_EMPTY(&vp->v_cache_dst) && 1960 vp->v_cache_dd == NULL) 1961 return; 1962 TAILQ_INIT(&ncps); 1963 vlp = VP2VNODELOCK(vp); 1964 vlp2 = NULL; 1965 mtx_lock(vlp); 1966 retry: 1967 while (!LIST_EMPTY(&vp->v_cache_src)) { 1968 ncp = LIST_FIRST(&vp->v_cache_src); 1969 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 1970 goto retry; 1971 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 1972 } 1973 while (!TAILQ_EMPTY(&vp->v_cache_dst)) { 1974 ncp = TAILQ_FIRST(&vp->v_cache_dst); 1975 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 1976 goto retry; 1977 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 1978 } 1979 ncp = vp->v_cache_dd; 1980 if (ncp != NULL) { 1981 KASSERT(ncp->nc_flag & NCF_ISDOTDOT, 1982 ("lost dotdot link")); 1983 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 1984 goto retry; 1985 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 1986 } 1987 KASSERT(vp->v_cache_dd == NULL, ("incomplete purge")); 1988 mtx_unlock(vlp); 1989 if (vlp2 != NULL) 1990 mtx_unlock(vlp2); 1991 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { 1992 cache_free(ncp); 1993 } 1994 } 1995 1996 /* 1997 * Invalidate all negative entries for a particular directory vnode. 1998 */ 1999 void 2000 cache_purge_negative(struct vnode *vp) 2001 { 2002 TAILQ_HEAD(, namecache) ncps; 2003 struct namecache *ncp, *nnp; 2004 struct mtx *vlp; 2005 2006 CTR1(KTR_VFS, "cache_purge_negative(%p)", vp); 2007 SDT_PROBE1(vfs, namecache, purge_negative, done, vp); 2008 if (LIST_EMPTY(&vp->v_cache_src)) 2009 return; 2010 TAILQ_INIT(&ncps); 2011 vlp = VP2VNODELOCK(vp); 2012 mtx_lock(vlp); 2013 LIST_FOREACH_SAFE(ncp, &vp->v_cache_src, nc_src, nnp) { 2014 if (!(ncp->nc_flag & NCF_NEGATIVE)) 2015 continue; 2016 cache_zap_negative_locked_vnode_kl(ncp, vp); 2017 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 2018 } 2019 mtx_unlock(vlp); 2020 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { 2021 cache_free(ncp); 2022 } 2023 } 2024 2025 /* 2026 * Flush all entries referencing a particular filesystem. 2027 */ 2028 void 2029 cache_purgevfs(struct mount *mp, bool force) 2030 { 2031 TAILQ_HEAD(, namecache) ncps; 2032 struct mtx *vlp1, *vlp2; 2033 struct rwlock *blp; 2034 struct nchashhead *bucket; 2035 struct namecache *ncp, *nnp; 2036 u_long i, j, n_nchash; 2037 int error; 2038 2039 /* Scan hash tables for applicable entries */ 2040 SDT_PROBE1(vfs, namecache, purgevfs, done, mp); 2041 if (!force && mp->mnt_nvnodelistsize <= ncpurgeminvnodes) 2042 return; 2043 TAILQ_INIT(&ncps); 2044 n_nchash = nchash + 1; 2045 vlp1 = vlp2 = NULL; 2046 for (i = 0; i < numbucketlocks; i++) { 2047 blp = (struct rwlock *)&bucketlocks[i]; 2048 rw_wlock(blp); 2049 for (j = i; j < n_nchash; j += numbucketlocks) { 2050 retry: 2051 bucket = &nchashtbl[j]; 2052 LIST_FOREACH_SAFE(ncp, bucket, nc_hash, nnp) { 2053 cache_assert_bucket_locked(ncp, RA_WLOCKED); 2054 if (ncp->nc_dvp->v_mount != mp) 2055 continue; 2056 error = cache_zap_wlocked_bucket_kl(ncp, blp, 2057 &vlp1, &vlp2); 2058 if (error != 0) 2059 goto retry; 2060 TAILQ_INSERT_HEAD(&ncps, ncp, nc_dst); 2061 } 2062 } 2063 rw_wunlock(blp); 2064 if (vlp1 == NULL && vlp2 == NULL) 2065 cache_maybe_yield(); 2066 } 2067 if (vlp1 != NULL) 2068 mtx_unlock(vlp1); 2069 if (vlp2 != NULL) 2070 mtx_unlock(vlp2); 2071 2072 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { 2073 cache_free(ncp); 2074 } 2075 } 2076 2077 /* 2078 * Perform canonical checks and cache lookup and pass on to filesystem 2079 * through the vop_cachedlookup only if needed. 2080 */ 2081 2082 int 2083 vfs_cache_lookup(struct vop_lookup_args *ap) 2084 { 2085 struct vnode *dvp; 2086 int error; 2087 struct vnode **vpp = ap->a_vpp; 2088 struct componentname *cnp = ap->a_cnp; 2089 struct ucred *cred = cnp->cn_cred; 2090 int flags = cnp->cn_flags; 2091 struct thread *td = cnp->cn_thread; 2092 2093 *vpp = NULL; 2094 dvp = ap->a_dvp; 2095 2096 if (dvp->v_type != VDIR) 2097 return (ENOTDIR); 2098 2099 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && 2100 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 2101 return (EROFS); 2102 2103 error = VOP_ACCESS(dvp, VEXEC, cred, td); 2104 if (error) 2105 return (error); 2106 2107 error = cache_lookup(dvp, vpp, cnp, NULL, NULL); 2108 if (error == 0) 2109 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); 2110 if (error == -1) 2111 return (0); 2112 return (error); 2113 } 2114 2115 /* 2116 * XXX All of these sysctls would probably be more productive dead. 2117 */ 2118 static int __read_mostly disablecwd; 2119 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, 2120 "Disable the getcwd syscall"); 2121 2122 /* Implementation of the getcwd syscall. */ 2123 int 2124 sys___getcwd(struct thread *td, struct __getcwd_args *uap) 2125 { 2126 2127 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen, 2128 MAXPATHLEN)); 2129 } 2130 2131 int 2132 kern___getcwd(struct thread *td, char *buf, enum uio_seg bufseg, size_t buflen, 2133 size_t path_max) 2134 { 2135 char *bp, *tmpbuf; 2136 struct filedesc *fdp; 2137 struct vnode *cdir, *rdir; 2138 int error; 2139 2140 if (__predict_false(disablecwd)) 2141 return (ENODEV); 2142 if (__predict_false(buflen < 2)) 2143 return (EINVAL); 2144 if (buflen > path_max) 2145 buflen = path_max; 2146 2147 tmpbuf = malloc(buflen, M_TEMP, M_WAITOK); 2148 fdp = td->td_proc->p_fd; 2149 FILEDESC_SLOCK(fdp); 2150 cdir = fdp->fd_cdir; 2151 vrefact(cdir); 2152 rdir = fdp->fd_rdir; 2153 vrefact(rdir); 2154 FILEDESC_SUNLOCK(fdp); 2155 error = vn_fullpath1(td, cdir, rdir, tmpbuf, &bp, buflen); 2156 vrele(rdir); 2157 vrele(cdir); 2158 2159 if (!error) { 2160 if (bufseg == UIO_SYSSPACE) 2161 bcopy(bp, buf, strlen(bp) + 1); 2162 else 2163 error = copyout(bp, buf, strlen(bp) + 1); 2164 #ifdef KTRACE 2165 if (KTRPOINT(curthread, KTR_NAMEI)) 2166 ktrnamei(bp); 2167 #endif 2168 } 2169 free(tmpbuf, M_TEMP); 2170 return (error); 2171 } 2172 2173 /* 2174 * Thus begins the fullpath magic. 2175 */ 2176 2177 static int __read_mostly disablefullpath; 2178 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0, 2179 "Disable the vn_fullpath function"); 2180 2181 /* 2182 * Retrieve the full filesystem path that correspond to a vnode from the name 2183 * cache (if available) 2184 */ 2185 int 2186 vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf) 2187 { 2188 char *buf; 2189 struct filedesc *fdp; 2190 struct vnode *rdir; 2191 int error; 2192 2193 if (__predict_false(disablefullpath)) 2194 return (ENODEV); 2195 if (__predict_false(vn == NULL)) 2196 return (EINVAL); 2197 2198 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 2199 fdp = td->td_proc->p_fd; 2200 FILEDESC_SLOCK(fdp); 2201 rdir = fdp->fd_rdir; 2202 vrefact(rdir); 2203 FILEDESC_SUNLOCK(fdp); 2204 error = vn_fullpath1(td, vn, rdir, buf, retbuf, MAXPATHLEN); 2205 vrele(rdir); 2206 2207 if (!error) 2208 *freebuf = buf; 2209 else 2210 free(buf, M_TEMP); 2211 return (error); 2212 } 2213 2214 /* 2215 * This function is similar to vn_fullpath, but it attempts to lookup the 2216 * pathname relative to the global root mount point. This is required for the 2217 * auditing sub-system, as audited pathnames must be absolute, relative to the 2218 * global root mount point. 2219 */ 2220 int 2221 vn_fullpath_global(struct thread *td, struct vnode *vn, 2222 char **retbuf, char **freebuf) 2223 { 2224 char *buf; 2225 int error; 2226 2227 if (__predict_false(disablefullpath)) 2228 return (ENODEV); 2229 if (__predict_false(vn == NULL)) 2230 return (EINVAL); 2231 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 2232 error = vn_fullpath1(td, vn, rootvnode, buf, retbuf, MAXPATHLEN); 2233 if (!error) 2234 *freebuf = buf; 2235 else 2236 free(buf, M_TEMP); 2237 return (error); 2238 } 2239 2240 int 2241 vn_vptocnp(struct vnode **vp, struct ucred *cred, char *buf, u_int *buflen) 2242 { 2243 struct vnode *dvp; 2244 struct namecache *ncp; 2245 struct mtx *vlp; 2246 int error; 2247 2248 vlp = VP2VNODELOCK(*vp); 2249 mtx_lock(vlp); 2250 TAILQ_FOREACH(ncp, &((*vp)->v_cache_dst), nc_dst) { 2251 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 2252 break; 2253 } 2254 if (ncp != NULL) { 2255 if (*buflen < ncp->nc_nlen) { 2256 mtx_unlock(vlp); 2257 vrele(*vp); 2258 counter_u64_add(numfullpathfail4, 1); 2259 error = ENOMEM; 2260 SDT_PROBE3(vfs, namecache, fullpath, return, error, 2261 vp, NULL); 2262 return (error); 2263 } 2264 *buflen -= ncp->nc_nlen; 2265 memcpy(buf + *buflen, ncp->nc_name, ncp->nc_nlen); 2266 SDT_PROBE3(vfs, namecache, fullpath, hit, ncp->nc_dvp, 2267 ncp->nc_name, vp); 2268 dvp = *vp; 2269 *vp = ncp->nc_dvp; 2270 vref(*vp); 2271 mtx_unlock(vlp); 2272 vrele(dvp); 2273 return (0); 2274 } 2275 SDT_PROBE1(vfs, namecache, fullpath, miss, vp); 2276 2277 mtx_unlock(vlp); 2278 vn_lock(*vp, LK_SHARED | LK_RETRY); 2279 error = VOP_VPTOCNP(*vp, &dvp, cred, buf, buflen); 2280 vput(*vp); 2281 if (error) { 2282 counter_u64_add(numfullpathfail2, 1); 2283 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); 2284 return (error); 2285 } 2286 2287 *vp = dvp; 2288 if (dvp->v_iflag & VI_DOOMED) { 2289 /* forced unmount */ 2290 vrele(dvp); 2291 error = ENOENT; 2292 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); 2293 return (error); 2294 } 2295 /* 2296 * *vp has its use count incremented still. 2297 */ 2298 2299 return (0); 2300 } 2301 2302 /* 2303 * The magic behind kern___getcwd() and vn_fullpath(). 2304 */ 2305 static int 2306 vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 2307 char *buf, char **retbuf, u_int buflen) 2308 { 2309 int error, slash_prefixed; 2310 #ifdef KDTRACE_HOOKS 2311 struct vnode *startvp = vp; 2312 #endif 2313 struct vnode *vp1; 2314 2315 buflen--; 2316 buf[buflen] = '\0'; 2317 error = 0; 2318 slash_prefixed = 0; 2319 2320 SDT_PROBE1(vfs, namecache, fullpath, entry, vp); 2321 counter_u64_add(numfullpathcalls, 1); 2322 vref(vp); 2323 if (vp->v_type != VDIR) { 2324 error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen); 2325 if (error) 2326 return (error); 2327 if (buflen == 0) { 2328 vrele(vp); 2329 return (ENOMEM); 2330 } 2331 buf[--buflen] = '/'; 2332 slash_prefixed = 1; 2333 } 2334 while (vp != rdir && vp != rootvnode) { 2335 /* 2336 * The vp vnode must be already fully constructed, 2337 * since it is either found in namecache or obtained 2338 * from VOP_VPTOCNP(). We may test for VV_ROOT safely 2339 * without obtaining the vnode lock. 2340 */ 2341 if ((vp->v_vflag & VV_ROOT) != 0) { 2342 vn_lock(vp, LK_RETRY | LK_SHARED); 2343 2344 /* 2345 * With the vnode locked, check for races with 2346 * unmount, forced or not. Note that we 2347 * already verified that vp is not equal to 2348 * the root vnode, which means that 2349 * mnt_vnodecovered can be NULL only for the 2350 * case of unmount. 2351 */ 2352 if ((vp->v_iflag & VI_DOOMED) != 0 || 2353 (vp1 = vp->v_mount->mnt_vnodecovered) == NULL || 2354 vp1->v_mountedhere != vp->v_mount) { 2355 vput(vp); 2356 error = ENOENT; 2357 SDT_PROBE3(vfs, namecache, fullpath, return, 2358 error, vp, NULL); 2359 break; 2360 } 2361 2362 vref(vp1); 2363 vput(vp); 2364 vp = vp1; 2365 continue; 2366 } 2367 if (vp->v_type != VDIR) { 2368 vrele(vp); 2369 counter_u64_add(numfullpathfail1, 1); 2370 error = ENOTDIR; 2371 SDT_PROBE3(vfs, namecache, fullpath, return, 2372 error, vp, NULL); 2373 break; 2374 } 2375 error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen); 2376 if (error) 2377 break; 2378 if (buflen == 0) { 2379 vrele(vp); 2380 error = ENOMEM; 2381 SDT_PROBE3(vfs, namecache, fullpath, return, error, 2382 startvp, NULL); 2383 break; 2384 } 2385 buf[--buflen] = '/'; 2386 slash_prefixed = 1; 2387 } 2388 if (error) 2389 return (error); 2390 if (!slash_prefixed) { 2391 if (buflen == 0) { 2392 vrele(vp); 2393 counter_u64_add(numfullpathfail4, 1); 2394 SDT_PROBE3(vfs, namecache, fullpath, return, ENOMEM, 2395 startvp, NULL); 2396 return (ENOMEM); 2397 } 2398 buf[--buflen] = '/'; 2399 } 2400 counter_u64_add(numfullpathfound, 1); 2401 vrele(vp); 2402 2403 SDT_PROBE3(vfs, namecache, fullpath, return, 0, startvp, buf + buflen); 2404 *retbuf = buf + buflen; 2405 return (0); 2406 } 2407 2408 struct vnode * 2409 vn_dir_dd_ino(struct vnode *vp) 2410 { 2411 struct namecache *ncp; 2412 struct vnode *ddvp; 2413 struct mtx *vlp; 2414 2415 ASSERT_VOP_LOCKED(vp, "vn_dir_dd_ino"); 2416 vlp = VP2VNODELOCK(vp); 2417 mtx_lock(vlp); 2418 TAILQ_FOREACH(ncp, &(vp->v_cache_dst), nc_dst) { 2419 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) 2420 continue; 2421 ddvp = ncp->nc_dvp; 2422 vhold(ddvp); 2423 mtx_unlock(vlp); 2424 if (vget(ddvp, LK_SHARED | LK_NOWAIT | LK_VNHELD, curthread)) 2425 return (NULL); 2426 return (ddvp); 2427 } 2428 mtx_unlock(vlp); 2429 return (NULL); 2430 } 2431 2432 int 2433 vn_commname(struct vnode *vp, char *buf, u_int buflen) 2434 { 2435 struct namecache *ncp; 2436 struct mtx *vlp; 2437 int l; 2438 2439 vlp = VP2VNODELOCK(vp); 2440 mtx_lock(vlp); 2441 TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst) 2442 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 2443 break; 2444 if (ncp == NULL) { 2445 mtx_unlock(vlp); 2446 return (ENOENT); 2447 } 2448 l = min(ncp->nc_nlen, buflen - 1); 2449 memcpy(buf, ncp->nc_name, l); 2450 mtx_unlock(vlp); 2451 buf[l] = '\0'; 2452 return (0); 2453 } 2454 2455 /* ABI compat shims for old kernel modules. */ 2456 #undef cache_enter 2457 2458 void cache_enter(struct vnode *dvp, struct vnode *vp, 2459 struct componentname *cnp); 2460 2461 void 2462 cache_enter(struct vnode *dvp, struct vnode *vp, struct componentname *cnp) 2463 { 2464 2465 cache_enter_time(dvp, vp, cnp, NULL, NULL); 2466 } 2467 2468 /* 2469 * This function updates path string to vnode's full global path 2470 * and checks the size of the new path string against the pathlen argument. 2471 * 2472 * Requires a locked, referenced vnode. 2473 * Vnode is re-locked on success or ENODEV, otherwise unlocked. 2474 * 2475 * If sysctl debug.disablefullpath is set, ENODEV is returned, 2476 * vnode is left locked and path remain untouched. 2477 * 2478 * If vp is a directory, the call to vn_fullpath_global() always succeeds 2479 * because it falls back to the ".." lookup if the namecache lookup fails. 2480 */ 2481 int 2482 vn_path_to_global_path(struct thread *td, struct vnode *vp, char *path, 2483 u_int pathlen) 2484 { 2485 struct nameidata nd; 2486 struct vnode *vp1; 2487 char *rpath, *fbuf; 2488 int error; 2489 2490 ASSERT_VOP_ELOCKED(vp, __func__); 2491 2492 /* Return ENODEV if sysctl debug.disablefullpath==1 */ 2493 if (__predict_false(disablefullpath)) 2494 return (ENODEV); 2495 2496 /* Construct global filesystem path from vp. */ 2497 VOP_UNLOCK(vp, 0); 2498 error = vn_fullpath_global(td, vp, &rpath, &fbuf); 2499 2500 if (error != 0) { 2501 vrele(vp); 2502 return (error); 2503 } 2504 2505 if (strlen(rpath) >= pathlen) { 2506 vrele(vp); 2507 error = ENAMETOOLONG; 2508 goto out; 2509 } 2510 2511 /* 2512 * Re-lookup the vnode by path to detect a possible rename. 2513 * As a side effect, the vnode is relocked. 2514 * If vnode was renamed, return ENOENT. 2515 */ 2516 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1, 2517 UIO_SYSSPACE, path, td); 2518 error = namei(&nd); 2519 if (error != 0) { 2520 vrele(vp); 2521 goto out; 2522 } 2523 NDFREE(&nd, NDF_ONLY_PNBUF); 2524 vp1 = nd.ni_vp; 2525 vrele(vp); 2526 if (vp1 == vp) 2527 strcpy(path, rpath); 2528 else { 2529 vput(vp1); 2530 error = ENOENT; 2531 } 2532 2533 out: 2534 free(fbuf, M_TEMP); 2535 return (error); 2536 } 2537 2538 #ifdef DDB 2539 static void 2540 db_print_vpath(struct vnode *vp) 2541 { 2542 2543 while (vp != NULL) { 2544 db_printf("%p: ", vp); 2545 if (vp == rootvnode) { 2546 db_printf("/"); 2547 vp = NULL; 2548 } else { 2549 if (vp->v_vflag & VV_ROOT) { 2550 db_printf("<mount point>"); 2551 vp = vp->v_mount->mnt_vnodecovered; 2552 } else { 2553 struct namecache *ncp; 2554 char *ncn; 2555 int i; 2556 2557 ncp = TAILQ_FIRST(&vp->v_cache_dst); 2558 if (ncp != NULL) { 2559 ncn = ncp->nc_name; 2560 for (i = 0; i < ncp->nc_nlen; i++) 2561 db_printf("%c", *ncn++); 2562 vp = ncp->nc_dvp; 2563 } else { 2564 vp = NULL; 2565 } 2566 } 2567 } 2568 db_printf("\n"); 2569 } 2570 2571 return; 2572 } 2573 2574 DB_SHOW_COMMAND(vpath, db_show_vpath) 2575 { 2576 struct vnode *vp; 2577 2578 if (!have_addr) { 2579 db_printf("usage: show vpath <struct vnode *>\n"); 2580 return; 2581 } 2582 2583 vp = (struct vnode *)addr; 2584 db_print_vpath(vp); 2585 } 2586 2587 #endif
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