1 /*- 2 * Copyright (c) 1989, 1993, 1995 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Poul-Henning Kamp of the FreeBSD Project. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * @(#)vfs_cache.c 8.5 (Berkeley) 3/22/95 33 */ 34 35 #include <sys/cdefs.h> 36 __FBSDID("$FreeBSD$"); 37 38 #include "opt_ktrace.h" 39 40 #include <sys/param.h> 41 #include <sys/systm.h> 42 #include <sys/counter.h> 43 #include <sys/filedesc.h> 44 #include <sys/fnv_hash.h> 45 #include <sys/kernel.h> 46 #include <sys/lock.h> 47 #include <sys/malloc.h> 48 #include <sys/fcntl.h> 49 #include <sys/mount.h> 50 #include <sys/namei.h> 51 #include <sys/proc.h> 52 #include <sys/rwlock.h> 53 #include <sys/sdt.h> 54 #include <sys/smp.h> 55 #include <sys/syscallsubr.h> 56 #include <sys/sysctl.h> 57 #include <sys/sysproto.h> 58 #include <sys/vnode.h> 59 #ifdef KTRACE 60 #include <sys/ktrace.h> 61 #endif 62 63 #include <vm/uma.h> 64 65 SDT_PROVIDER_DECLARE(vfs); 66 SDT_PROBE_DEFINE3(vfs, namecache, enter, done, "struct vnode *", "char *", 67 "struct vnode *"); 68 SDT_PROBE_DEFINE2(vfs, namecache, enter_negative, done, "struct vnode *", 69 "char *"); 70 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, entry, "struct vnode *"); 71 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, hit, "struct vnode *", 72 "char *", "struct vnode *"); 73 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, miss, "struct vnode *"); 74 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, return, "int", 75 "struct vnode *", "char *"); 76 SDT_PROBE_DEFINE3(vfs, namecache, lookup, hit, "struct vnode *", "char *", 77 "struct vnode *"); 78 SDT_PROBE_DEFINE2(vfs, namecache, lookup, hit__negative, 79 "struct vnode *", "char *"); 80 SDT_PROBE_DEFINE2(vfs, namecache, lookup, miss, "struct vnode *", 81 "char *"); 82 SDT_PROBE_DEFINE1(vfs, namecache, purge, done, "struct vnode *"); 83 SDT_PROBE_DEFINE1(vfs, namecache, purge_negative, done, "struct vnode *"); 84 SDT_PROBE_DEFINE1(vfs, namecache, purgevfs, done, "struct mount *"); 85 SDT_PROBE_DEFINE3(vfs, namecache, zap, done, "struct vnode *", "char *", 86 "struct vnode *"); 87 SDT_PROBE_DEFINE2(vfs, namecache, zap_negative, done, "struct vnode *", 88 "char *"); 89 90 /* 91 * This structure describes the elements in the cache of recent 92 * names looked up by namei. 93 */ 94 95 struct namecache { 96 LIST_ENTRY(namecache) nc_hash; /* hash chain */ 97 LIST_ENTRY(namecache) nc_src; /* source vnode list */ 98 TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */ 99 struct vnode *nc_dvp; /* vnode of parent of name */ 100 struct vnode *nc_vp; /* vnode the name refers to */ 101 u_char nc_flag; /* flag bits */ 102 u_char nc_nlen; /* length of name */ 103 char nc_name[0]; /* segment name + nul */ 104 }; 105 106 /* 107 * struct namecache_ts repeats struct namecache layout up to the 108 * nc_nlen member. 109 * struct namecache_ts is used in place of struct namecache when time(s) need 110 * to be stored. The nc_dotdottime field is used when a cache entry is mapping 111 * both a non-dotdot directory name plus dotdot for the directory's 112 * parent. 113 */ 114 struct namecache_ts { 115 LIST_ENTRY(namecache) nc_hash; /* hash chain */ 116 LIST_ENTRY(namecache) nc_src; /* source vnode list */ 117 TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */ 118 struct vnode *nc_dvp; /* vnode of parent of name */ 119 struct vnode *nc_vp; /* vnode the name refers to */ 120 u_char nc_flag; /* flag bits */ 121 u_char nc_nlen; /* length of name */ 122 struct timespec nc_time; /* timespec provided by fs */ 123 struct timespec nc_dotdottime; /* dotdot timespec provided by fs */ 124 int nc_ticks; /* ticks value when entry was added */ 125 char nc_name[0]; /* segment name + nul */ 126 }; 127 128 /* 129 * Flags in namecache.nc_flag 130 */ 131 #define NCF_WHITE 0x01 132 #define NCF_ISDOTDOT 0x02 133 #define NCF_TS 0x04 134 #define NCF_DTS 0x08 135 #define NCF_DVDROP 0x10 136 137 /* 138 * Name caching works as follows: 139 * 140 * Names found by directory scans are retained in a cache 141 * for future reference. It is managed LRU, so frequently 142 * used names will hang around. Cache is indexed by hash value 143 * obtained from (vp, name) where vp refers to the directory 144 * containing name. 145 * 146 * If it is a "negative" entry, (i.e. for a name that is known NOT to 147 * exist) the vnode pointer will be NULL. 148 * 149 * Upon reaching the last segment of a path, if the reference 150 * is for DELETE, or NOCACHE is set (rewrite), and the 151 * name is located in the cache, it will be dropped. 152 * 153 * These locks are used (in the order in which they can be taken): 154 * NAME TYPE ROLE 155 * vnodelock mtx vnode lists and v_cache_dd field protection 156 * bucketlock rwlock for access to given set of hash buckets 157 * ncneg_mtx mtx negative entry LRU management 158 * 159 * Additionally, ncneg_shrink_lock mtx is used to have at most one thread 160 * shrinking the LRU list. 161 * 162 * It is legal to take multiple vnodelock and bucketlock locks. The locking 163 * order is lower address first. Both are recursive. 164 * 165 * "." lookups are lockless. 166 * 167 * ".." and vnode -> name lookups require vnodelock. 168 * 169 * name -> vnode lookup requires the relevant bucketlock to be held for reading. 170 * 171 * Insertions and removals of entries require involved vnodes and bucketlocks 172 * to be write-locked to prevent other threads from seeing the entry. 173 * 174 * Some lookups result in removal of the found entry (e.g. getting rid of a 175 * negative entry with the intent to create a positive one), which poses a 176 * problem when multiple threads reach the state. Similarly, two different 177 * threads can purge two different vnodes and try to remove the same name. 178 * 179 * If the already held vnode lock is lower than the second required lock, we 180 * can just take the other lock. However, in the opposite case, this could 181 * deadlock. As such, this is resolved by trylocking and if that fails unlocking 182 * the first node, locking everything in order and revalidating the state. 183 */ 184 185 /* 186 * Structures associated with name caching. 187 */ 188 #define NCHHASH(hash) \ 189 (&nchashtbl[(hash) & nchash]) 190 static LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */ 191 static TAILQ_HEAD(, namecache) ncneg; /* Hash Table */ 192 static u_long nchash; /* size of hash table */ 193 SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, 194 "Size of namecache hash table"); 195 static u_long ncnegfactor = 16; /* ratio of negative entries */ 196 SYSCTL_ULONG(_vfs, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, 197 "Ratio of negative namecache entries"); 198 static u_long numneg; /* number of negative entries allocated */ 199 SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, 200 "Number of negative entries in namecache"); 201 static u_long numcache; /* number of cache entries allocated */ 202 SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, 203 "Number of namecache entries"); 204 static u_long numcachehv; /* number of cache entries with vnodes held */ 205 SYSCTL_ULONG(_debug, OID_AUTO, numcachehv, CTLFLAG_RD, &numcachehv, 0, 206 "Number of namecache entries with vnodes held"); 207 u_int ncsizefactor = 2; 208 SYSCTL_UINT(_vfs, OID_AUTO, ncsizefactor, CTLFLAG_RW, &ncsizefactor, 0, 209 "Size factor for namecache"); 210 static u_int ncpurgeminvnodes; 211 SYSCTL_UINT(_vfs, OID_AUTO, ncpurgeminvnodes, CTLFLAG_RW, &ncpurgeminvnodes, 0, 212 "Number of vnodes below which purgevfs ignores the request"); 213 214 struct nchstats nchstats; /* cache effectiveness statistics */ 215 216 static struct mtx ncneg_shrink_lock; 217 MTX_SYSINIT(vfscache_shrink_neg, &ncneg_shrink_lock, "Name Cache shrink neg", 218 MTX_DEF); 219 220 static struct mtx_padalign ncneg_mtx; 221 MTX_SYSINIT(vfscache_neg, &ncneg_mtx, "ncneg", MTX_DEF); 222 223 static u_int numbucketlocks; 224 static struct rwlock_padalign *bucketlocks; 225 #define HASH2BUCKETLOCK(hash) \ 226 ((struct rwlock *)(&bucketlocks[((hash) % numbucketlocks)])) 227 228 static u_int numvnodelocks; 229 static struct mtx *vnodelocks; 230 static inline struct mtx * 231 VP2VNODELOCK(struct vnode *vp) 232 { 233 struct mtx *vlp; 234 235 if (vp == NULL) 236 return (NULL); 237 vlp = &vnodelocks[(((uintptr_t)(vp) >> 8) % numvnodelocks)]; 238 return (vlp); 239 } 240 241 /* 242 * UMA zones for the VFS cache. 243 * 244 * The small cache is used for entries with short names, which are the 245 * most common. The large cache is used for entries which are too big to 246 * fit in the small cache. 247 */ 248 static uma_zone_t cache_zone_small; 249 static uma_zone_t cache_zone_small_ts; 250 static uma_zone_t cache_zone_large; 251 static uma_zone_t cache_zone_large_ts; 252 253 #define CACHE_PATH_CUTOFF 35 254 255 static struct namecache * 256 cache_alloc(int len, int ts) 257 { 258 259 if (len > CACHE_PATH_CUTOFF) { 260 if (ts) 261 return (uma_zalloc(cache_zone_large_ts, M_WAITOK)); 262 else 263 return (uma_zalloc(cache_zone_large, M_WAITOK)); 264 } 265 if (ts) 266 return (uma_zalloc(cache_zone_small_ts, M_WAITOK)); 267 else 268 return (uma_zalloc(cache_zone_small, M_WAITOK)); 269 } 270 271 static void 272 cache_free(struct namecache *ncp) 273 { 274 int ts; 275 276 if (ncp == NULL) 277 return; 278 ts = ncp->nc_flag & NCF_TS; 279 if ((ncp->nc_flag & NCF_DVDROP) != 0) 280 vdrop(ncp->nc_dvp); 281 if (ncp->nc_nlen <= CACHE_PATH_CUTOFF) { 282 if (ts) 283 uma_zfree(cache_zone_small_ts, ncp); 284 else 285 uma_zfree(cache_zone_small, ncp); 286 } else if (ts) 287 uma_zfree(cache_zone_large_ts, ncp); 288 else 289 uma_zfree(cache_zone_large, ncp); 290 } 291 292 static char * 293 nc_get_name(struct namecache *ncp) 294 { 295 struct namecache_ts *ncp_ts; 296 297 if ((ncp->nc_flag & NCF_TS) == 0) 298 return (ncp->nc_name); 299 ncp_ts = (struct namecache_ts *)ncp; 300 return (ncp_ts->nc_name); 301 } 302 303 static void 304 cache_out_ts(struct namecache *ncp, struct timespec *tsp, int *ticksp) 305 { 306 307 KASSERT((ncp->nc_flag & NCF_TS) != 0 || 308 (tsp == NULL && ticksp == NULL), 309 ("No NCF_TS")); 310 311 if (tsp != NULL) 312 *tsp = ((struct namecache_ts *)ncp)->nc_time; 313 if (ticksp != NULL) 314 *ticksp = ((struct namecache_ts *)ncp)->nc_ticks; 315 } 316 317 static int doingcache = 1; /* 1 => enable the cache */ 318 SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0, 319 "VFS namecache enabled"); 320 321 /* Export size information to userland */ 322 SYSCTL_INT(_debug_sizeof, OID_AUTO, namecache, CTLFLAG_RD, SYSCTL_NULL_INT_PTR, 323 sizeof(struct namecache), "sizeof(struct namecache)"); 324 325 /* 326 * The new name cache statistics 327 */ 328 static SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, 329 "Name cache statistics"); 330 #define STATNODE_ULONG(name, descr) \ 331 SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, descr); 332 #define STATNODE_COUNTER(name, descr) \ 333 static counter_u64_t name; \ 334 SYSCTL_COUNTER_U64(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, descr); 335 STATNODE_ULONG(numneg, "Number of negative cache entries"); 336 STATNODE_ULONG(numcache, "Number of cache entries"); 337 STATNODE_COUNTER(numcalls, "Number of cache lookups"); 338 STATNODE_COUNTER(dothits, "Number of '.' hits"); 339 STATNODE_COUNTER(dotdothits, "Number of '..' hits"); 340 STATNODE_COUNTER(numchecks, "Number of checks in lookup"); 341 STATNODE_COUNTER(nummiss, "Number of cache misses"); 342 STATNODE_COUNTER(nummisszap, "Number of cache misses we do not want to cache"); 343 STATNODE_COUNTER(numposzaps, 344 "Number of cache hits (positive) we do not want to cache"); 345 STATNODE_COUNTER(numposhits, "Number of cache hits (positive)"); 346 STATNODE_COUNTER(numnegzaps, 347 "Number of cache hits (negative) we do not want to cache"); 348 STATNODE_COUNTER(numneghits, "Number of cache hits (negative)"); 349 /* These count for kern___getcwd(), too. */ 350 STATNODE_COUNTER(numfullpathcalls, "Number of fullpath search calls"); 351 STATNODE_COUNTER(numfullpathfail1, "Number of fullpath search errors (ENOTDIR)"); 352 STATNODE_COUNTER(numfullpathfail2, 353 "Number of fullpath search errors (VOP_VPTOCNP failures)"); 354 STATNODE_COUNTER(numfullpathfail4, "Number of fullpath search errors (ENOMEM)"); 355 STATNODE_COUNTER(numfullpathfound, "Number of successful fullpath calls"); 356 static long zap_and_exit_bucket_fail; STATNODE_ULONG(zap_and_exit_bucket_fail, 357 "Number of times zap_and_exit failed to lock"); 358 static long cache_lock_vnodes_cel_3_failures; 359 STATNODE_ULONG(cache_lock_vnodes_cel_3_failures, 360 "Number of times 3-way vnode locking failed"); 361 362 static void cache_zap_locked(struct namecache *ncp, bool neg_locked); 363 static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 364 char *buf, char **retbuf, u_int buflen); 365 366 static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); 367 368 static int cache_yield; 369 SYSCTL_INT(_vfs_cache, OID_AUTO, yield, CTLFLAG_RD, &cache_yield, 0, 370 "Number of times cache called yield"); 371 372 static void 373 cache_maybe_yield(void) 374 { 375 376 if (should_yield()) { 377 cache_yield++; 378 kern_yield(PRI_USER); 379 } 380 } 381 382 static inline void 383 cache_assert_vlp_locked(struct mtx *vlp) 384 { 385 386 if (vlp != NULL) 387 mtx_assert(vlp, MA_OWNED); 388 } 389 390 static inline void 391 cache_assert_vnode_locked(struct vnode *vp) 392 { 393 struct mtx *vlp; 394 395 vlp = VP2VNODELOCK(vp); 396 cache_assert_vlp_locked(vlp); 397 } 398 399 static uint32_t 400 cache_get_hash(char *name, u_char len, struct vnode *dvp) 401 { 402 uint32_t hash; 403 404 hash = fnv_32_buf(name, len, FNV1_32_INIT); 405 hash = fnv_32_buf(&dvp, sizeof(dvp), hash); 406 return (hash); 407 } 408 409 static inline struct rwlock * 410 NCP2BUCKETLOCK(struct namecache *ncp) 411 { 412 uint32_t hash; 413 414 hash = cache_get_hash(nc_get_name(ncp), ncp->nc_nlen, ncp->nc_dvp); 415 return (HASH2BUCKETLOCK(hash)); 416 } 417 418 #ifdef INVARIANTS 419 static void 420 cache_assert_bucket_locked(struct namecache *ncp, int mode) 421 { 422 struct rwlock *blp; 423 424 blp = NCP2BUCKETLOCK(ncp); 425 rw_assert(blp, mode); 426 } 427 #else 428 #define cache_assert_bucket_locked(x, y) do { } while (0) 429 #endif 430 431 #define cache_sort(x, y) _cache_sort((void **)(x), (void **)(y)) 432 static void 433 _cache_sort(void **p1, void **p2) 434 { 435 void *tmp; 436 437 if (*p1 > *p2) { 438 tmp = *p2; 439 *p2 = *p1; 440 *p1 = tmp; 441 } 442 } 443 444 static void 445 cache_lock_all_buckets(void) 446 { 447 u_int i; 448 449 for (i = 0; i < numbucketlocks; i++) 450 rw_wlock(&bucketlocks[i]); 451 } 452 453 static void 454 cache_unlock_all_buckets(void) 455 { 456 u_int i; 457 458 for (i = 0; i < numbucketlocks; i++) 459 rw_wunlock(&bucketlocks[i]); 460 } 461 462 static void 463 cache_lock_all_vnodes(void) 464 { 465 u_int i; 466 467 for (i = 0; i < numvnodelocks; i++) 468 mtx_lock(&vnodelocks[i]); 469 } 470 471 static void 472 cache_unlock_all_vnodes(void) 473 { 474 u_int i; 475 476 for (i = 0; i < numvnodelocks; i++) 477 mtx_unlock(&vnodelocks[i]); 478 } 479 480 static int 481 cache_trylock_vnodes(struct mtx *vlp1, struct mtx *vlp2) 482 { 483 484 cache_sort(&vlp1, &vlp2); 485 MPASS(vlp2 != NULL); 486 487 if (vlp1 != NULL) { 488 if (!mtx_trylock(vlp1)) 489 return (EAGAIN); 490 } 491 if (!mtx_trylock(vlp2)) { 492 if (vlp1 != NULL) 493 mtx_unlock(vlp1); 494 return (EAGAIN); 495 } 496 497 return (0); 498 } 499 500 static void 501 cache_unlock_vnodes(struct mtx *vlp1, struct mtx *vlp2) 502 { 503 504 MPASS(vlp1 != NULL || vlp2 != NULL); 505 506 if (vlp1 != NULL) 507 mtx_unlock(vlp1); 508 if (vlp2 != NULL) 509 mtx_unlock(vlp2); 510 } 511 512 static int 513 sysctl_nchstats(SYSCTL_HANDLER_ARGS) 514 { 515 struct nchstats snap; 516 517 if (req->oldptr == NULL) 518 return (SYSCTL_OUT(req, 0, sizeof(snap))); 519 520 snap = nchstats; 521 snap.ncs_goodhits = counter_u64_fetch(numposhits); 522 snap.ncs_neghits = counter_u64_fetch(numneghits); 523 snap.ncs_badhits = counter_u64_fetch(numposzaps) + 524 counter_u64_fetch(numnegzaps); 525 snap.ncs_miss = counter_u64_fetch(nummisszap) + 526 counter_u64_fetch(nummiss); 527 528 return (SYSCTL_OUT(req, &snap, sizeof(snap))); 529 } 530 SYSCTL_PROC(_vfs_cache, OID_AUTO, nchstats, CTLTYPE_OPAQUE | CTLFLAG_RD | 531 CTLFLAG_MPSAFE, 0, 0, sysctl_nchstats, "LU", 532 "VFS cache effectiveness statistics"); 533 534 #ifdef DIAGNOSTIC 535 /* 536 * Grab an atomic snapshot of the name cache hash chain lengths 537 */ 538 static SYSCTL_NODE(_debug, OID_AUTO, hashstat, CTLFLAG_RW, NULL, 539 "hash table stats"); 540 541 static int 542 sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS) 543 { 544 struct nchashhead *ncpp; 545 struct namecache *ncp; 546 int i, error, n_nchash, *cntbuf; 547 548 retry: 549 n_nchash = nchash + 1; /* nchash is max index, not count */ 550 if (req->oldptr == NULL) 551 return SYSCTL_OUT(req, 0, n_nchash * sizeof(int)); 552 cntbuf = malloc(n_nchash * sizeof(int), M_TEMP, M_ZERO | M_WAITOK); 553 cache_lock_all_buckets(); 554 if (n_nchash != nchash + 1) { 555 cache_unlock_all_buckets(); 556 free(cntbuf, M_TEMP); 557 goto retry; 558 } 559 /* Scan hash tables counting entries */ 560 for (ncpp = nchashtbl, i = 0; i < n_nchash; ncpp++, i++) 561 LIST_FOREACH(ncp, ncpp, nc_hash) 562 cntbuf[i]++; 563 cache_unlock_all_buckets(); 564 for (error = 0, i = 0; i < n_nchash; i++) 565 if ((error = SYSCTL_OUT(req, &cntbuf[i], sizeof(int))) != 0) 566 break; 567 free(cntbuf, M_TEMP); 568 return (error); 569 } 570 SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD| 571 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_rawnchash, "S,int", 572 "nchash chain lengths"); 573 574 static int 575 sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS) 576 { 577 int error; 578 struct nchashhead *ncpp; 579 struct namecache *ncp; 580 int n_nchash; 581 int count, maxlength, used, pct; 582 583 if (!req->oldptr) 584 return SYSCTL_OUT(req, 0, 4 * sizeof(int)); 585 586 cache_lock_all_buckets(); 587 n_nchash = nchash + 1; /* nchash is max index, not count */ 588 used = 0; 589 maxlength = 0; 590 591 /* Scan hash tables for applicable entries */ 592 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { 593 count = 0; 594 LIST_FOREACH(ncp, ncpp, nc_hash) { 595 count++; 596 } 597 if (count) 598 used++; 599 if (maxlength < count) 600 maxlength = count; 601 } 602 n_nchash = nchash + 1; 603 cache_unlock_all_buckets(); 604 pct = (used * 100) / (n_nchash / 100); 605 error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash)); 606 if (error) 607 return (error); 608 error = SYSCTL_OUT(req, &used, sizeof(used)); 609 if (error) 610 return (error); 611 error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength)); 612 if (error) 613 return (error); 614 error = SYSCTL_OUT(req, &pct, sizeof(pct)); 615 if (error) 616 return (error); 617 return (0); 618 } 619 SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD| 620 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_nchash, "I", 621 "nchash statistics (number of total/used buckets, maximum chain length, usage percentage)"); 622 #endif 623 624 /* 625 * Negative entries management 626 */ 627 static void 628 cache_negative_hit(struct namecache *ncp) 629 { 630 631 MPASS(ncp->nc_vp == NULL); 632 mtx_lock(&ncneg_mtx); 633 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 634 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 635 mtx_unlock(&ncneg_mtx); 636 } 637 638 static void 639 cache_negative_insert(struct namecache *ncp) 640 { 641 642 MPASS(ncp->nc_vp == NULL); 643 cache_assert_bucket_locked(ncp, RA_WLOCKED); 644 mtx_lock(&ncneg_mtx); 645 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 646 numneg++; 647 mtx_unlock(&ncneg_mtx); 648 } 649 650 static void 651 cache_negative_remove(struct namecache *ncp, bool neg_locked) 652 { 653 654 MPASS(ncp->nc_vp == NULL); 655 cache_assert_bucket_locked(ncp, RA_WLOCKED); 656 if (!neg_locked) 657 mtx_lock(&ncneg_mtx); 658 else 659 mtx_assert(&ncneg_mtx, MA_OWNED); 660 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 661 numneg--; 662 if (!neg_locked) 663 mtx_unlock(&ncneg_mtx); 664 } 665 666 static void 667 cache_negative_zap_one(void) 668 { 669 struct namecache *ncp, *ncp2; 670 struct mtx *dvlp; 671 struct rwlock *blp; 672 673 if (!mtx_trylock(&ncneg_shrink_lock)) 674 return; 675 676 mtx_lock(&ncneg_mtx); 677 ncp = TAILQ_FIRST(&ncneg); 678 if (ncp == NULL) { 679 mtx_unlock(&ncneg_mtx); 680 goto out; 681 } 682 MPASS(ncp->nc_vp == NULL); 683 dvlp = VP2VNODELOCK(ncp->nc_dvp); 684 blp = NCP2BUCKETLOCK(ncp); 685 mtx_unlock(&ncneg_mtx); 686 mtx_lock(dvlp); 687 rw_wlock(blp); 688 mtx_lock(&ncneg_mtx); 689 ncp2 = TAILQ_FIRST(&ncneg); 690 if (ncp != ncp2 || dvlp != VP2VNODELOCK(ncp2->nc_dvp) || 691 blp != NCP2BUCKETLOCK(ncp2) || ncp2->nc_vp != NULL) { 692 ncp = NULL; 693 goto out_unlock_all; 694 } 695 cache_zap_locked(ncp, true); 696 out_unlock_all: 697 mtx_unlock(&ncneg_mtx); 698 rw_wunlock(blp); 699 mtx_unlock(dvlp); 700 out: 701 mtx_unlock(&ncneg_shrink_lock); 702 cache_free(ncp); 703 } 704 705 /* 706 * cache_zap_locked(): 707 * 708 * Removes a namecache entry from cache, whether it contains an actual 709 * pointer to a vnode or if it is just a negative cache entry. 710 */ 711 static void 712 cache_zap_locked(struct namecache *ncp, bool neg_locked) 713 { 714 715 cache_assert_vnode_locked(ncp->nc_vp); 716 cache_assert_vnode_locked(ncp->nc_dvp); 717 cache_assert_bucket_locked(ncp, RA_WLOCKED); 718 719 CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp, ncp->nc_vp); 720 if (ncp->nc_vp != NULL) { 721 SDT_PROBE3(vfs, namecache, zap, done, ncp->nc_dvp, 722 nc_get_name(ncp), ncp->nc_vp); 723 } else { 724 SDT_PROBE2(vfs, namecache, zap_negative, done, ncp->nc_dvp, 725 nc_get_name(ncp)); 726 } 727 LIST_REMOVE(ncp, nc_hash); 728 if (ncp->nc_flag & NCF_ISDOTDOT) { 729 if (ncp == ncp->nc_dvp->v_cache_dd) 730 ncp->nc_dvp->v_cache_dd = NULL; 731 } else { 732 LIST_REMOVE(ncp, nc_src); 733 if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) { 734 ncp->nc_flag |= NCF_DVDROP; 735 atomic_subtract_rel_long(&numcachehv, 1); 736 } 737 } 738 if (ncp->nc_vp) { 739 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst); 740 if (ncp == ncp->nc_vp->v_cache_dd) 741 ncp->nc_vp->v_cache_dd = NULL; 742 } else { 743 cache_negative_remove(ncp, neg_locked); 744 } 745 atomic_subtract_rel_long(&numcache, 1); 746 } 747 748 static void 749 cache_zap_negative_locked_vnode_kl(struct namecache *ncp, struct vnode *vp) 750 { 751 struct rwlock *blp; 752 753 MPASS(ncp->nc_dvp == vp); 754 MPASS(ncp->nc_vp == NULL); 755 cache_assert_vnode_locked(vp); 756 757 blp = NCP2BUCKETLOCK(ncp); 758 rw_wlock(blp); 759 cache_zap_locked(ncp, false); 760 rw_wunlock(blp); 761 } 762 763 static bool 764 cache_zap_locked_vnode_kl2(struct namecache *ncp, struct vnode *vp, 765 struct mtx **vlpp) 766 { 767 struct mtx *pvlp, *vlp1, *vlp2, *to_unlock; 768 struct rwlock *blp; 769 770 MPASS(vp == ncp->nc_dvp || vp == ncp->nc_vp); 771 cache_assert_vnode_locked(vp); 772 773 if (ncp->nc_vp == NULL) { 774 if (*vlpp != NULL) { 775 mtx_unlock(*vlpp); 776 *vlpp = NULL; 777 } 778 cache_zap_negative_locked_vnode_kl(ncp, vp); 779 return (true); 780 } 781 782 pvlp = VP2VNODELOCK(vp); 783 blp = NCP2BUCKETLOCK(ncp); 784 vlp1 = VP2VNODELOCK(ncp->nc_dvp); 785 vlp2 = VP2VNODELOCK(ncp->nc_vp); 786 787 if (*vlpp == vlp1 || *vlpp == vlp2) { 788 to_unlock = *vlpp; 789 *vlpp = NULL; 790 } else { 791 if (*vlpp != NULL) { 792 mtx_unlock(*vlpp); 793 *vlpp = NULL; 794 } 795 cache_sort(&vlp1, &vlp2); 796 if (vlp1 == pvlp) { 797 mtx_lock(vlp2); 798 to_unlock = vlp2; 799 } else { 800 if (!mtx_trylock(vlp1)) 801 goto out_relock; 802 to_unlock = vlp1; 803 } 804 } 805 rw_wlock(blp); 806 cache_zap_locked(ncp, false); 807 rw_wunlock(blp); 808 if (to_unlock != NULL) 809 mtx_unlock(to_unlock); 810 return (true); 811 812 out_relock: 813 mtx_unlock(vlp2); 814 mtx_lock(vlp1); 815 mtx_lock(vlp2); 816 MPASS(*vlpp == NULL); 817 *vlpp = vlp1; 818 return (false); 819 } 820 821 static int 822 cache_zap_locked_vnode(struct namecache *ncp, struct vnode *vp) 823 { 824 struct mtx *pvlp, *vlp1, *vlp2, *to_unlock; 825 struct rwlock *blp; 826 int error = 0; 827 828 MPASS(vp == ncp->nc_dvp || vp == ncp->nc_vp); 829 cache_assert_vnode_locked(vp); 830 831 pvlp = VP2VNODELOCK(vp); 832 if (ncp->nc_vp == NULL) { 833 cache_zap_negative_locked_vnode_kl(ncp, vp); 834 goto out; 835 } 836 837 blp = NCP2BUCKETLOCK(ncp); 838 vlp1 = VP2VNODELOCK(ncp->nc_dvp); 839 vlp2 = VP2VNODELOCK(ncp->nc_vp); 840 cache_sort(&vlp1, &vlp2); 841 if (vlp1 == pvlp) { 842 mtx_lock(vlp2); 843 to_unlock = vlp2; 844 } else { 845 if (!mtx_trylock(vlp1)) { 846 error = EAGAIN; 847 goto out; 848 } 849 to_unlock = vlp1; 850 } 851 rw_wlock(blp); 852 cache_zap_locked(ncp, false); 853 rw_wunlock(blp); 854 mtx_unlock(to_unlock); 855 out: 856 mtx_unlock(pvlp); 857 return (error); 858 } 859 860 static int 861 cache_zap_rlocked_bucket(struct namecache *ncp, struct rwlock *blp) 862 { 863 struct mtx *dvlp, *vlp; 864 865 cache_assert_bucket_locked(ncp, RA_RLOCKED); 866 867 dvlp = VP2VNODELOCK(ncp->nc_dvp); 868 vlp = VP2VNODELOCK(ncp->nc_vp); 869 if (cache_trylock_vnodes(dvlp, vlp) == 0) { 870 rw_runlock(blp); 871 rw_wlock(blp); 872 cache_zap_locked(ncp, false); 873 rw_wunlock(blp); 874 cache_unlock_vnodes(dvlp, vlp); 875 return (0); 876 } 877 878 rw_runlock(blp); 879 return (EAGAIN); 880 } 881 882 static int 883 cache_zap_wlocked_bucket_kl(struct namecache *ncp, struct rwlock *blp, 884 struct mtx **vlpp1, struct mtx **vlpp2) 885 { 886 struct mtx *dvlp, *vlp; 887 888 cache_assert_bucket_locked(ncp, RA_WLOCKED); 889 890 dvlp = VP2VNODELOCK(ncp->nc_dvp); 891 vlp = VP2VNODELOCK(ncp->nc_vp); 892 cache_sort(&dvlp, &vlp); 893 894 if (*vlpp1 == dvlp && *vlpp2 == vlp) { 895 cache_zap_locked(ncp, false); 896 cache_unlock_vnodes(dvlp, vlp); 897 *vlpp1 = NULL; 898 *vlpp2 = NULL; 899 return (0); 900 } 901 902 if (*vlpp1 != NULL) 903 mtx_unlock(*vlpp1); 904 if (*vlpp2 != NULL) 905 mtx_unlock(*vlpp2); 906 *vlpp1 = NULL; 907 *vlpp2 = NULL; 908 909 if (cache_trylock_vnodes(dvlp, vlp) == 0) { 910 cache_zap_locked(ncp, false); 911 cache_unlock_vnodes(dvlp, vlp); 912 return (0); 913 } 914 915 rw_wunlock(blp); 916 *vlpp1 = dvlp; 917 *vlpp2 = vlp; 918 if (*vlpp1 != NULL) 919 mtx_lock(*vlpp1); 920 mtx_lock(*vlpp2); 921 rw_wlock(blp); 922 return (EAGAIN); 923 } 924 925 static void 926 cache_lookup_unlock(struct rwlock *blp, struct mtx *vlp) 927 { 928 929 if (blp != NULL) { 930 rw_runlock(blp); 931 mtx_assert(vlp, MA_NOTOWNED); 932 } else { 933 mtx_unlock(vlp); 934 } 935 } 936 937 /* 938 * Lookup an entry in the cache 939 * 940 * Lookup is called with dvp pointing to the directory to search, 941 * cnp pointing to the name of the entry being sought. If the lookup 942 * succeeds, the vnode is returned in *vpp, and a status of -1 is 943 * returned. If the lookup determines that the name does not exist 944 * (negative caching), a status of ENOENT is returned. If the lookup 945 * fails, a status of zero is returned. If the directory vnode is 946 * recycled out from under us due to a forced unmount, a status of 947 * ENOENT is returned. 948 * 949 * vpp is locked and ref'd on return. If we're looking up DOTDOT, dvp is 950 * unlocked. If we're looking up . an extra ref is taken, but the lock is 951 * not recursively acquired. 952 */ 953 954 int 955 cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, 956 struct timespec *tsp, int *ticksp) 957 { 958 struct namecache *ncp; 959 struct rwlock *blp; 960 struct mtx *dvlp, *dvlp2; 961 uint32_t hash; 962 int error, ltype; 963 964 if (!doingcache) { 965 cnp->cn_flags &= ~MAKEENTRY; 966 return (0); 967 } 968 retry: 969 blp = NULL; 970 dvlp = VP2VNODELOCK(dvp); 971 error = 0; 972 counter_u64_add(numcalls, 1); 973 974 if (cnp->cn_nameptr[0] == '.') { 975 if (cnp->cn_namelen == 1) { 976 *vpp = dvp; 977 CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .", 978 dvp, cnp->cn_nameptr); 979 counter_u64_add(dothits, 1); 980 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ".", *vpp); 981 if (tsp != NULL) 982 timespecclear(tsp); 983 if (ticksp != NULL) 984 *ticksp = ticks; 985 VREF(*vpp); 986 /* 987 * When we lookup "." we still can be asked to lock it 988 * differently... 989 */ 990 ltype = cnp->cn_lkflags & LK_TYPE_MASK; 991 if (ltype != VOP_ISLOCKED(*vpp)) { 992 if (ltype == LK_EXCLUSIVE) { 993 vn_lock(*vpp, LK_UPGRADE | LK_RETRY); 994 if ((*vpp)->v_iflag & VI_DOOMED) { 995 /* forced unmount */ 996 vrele(*vpp); 997 *vpp = NULL; 998 return (ENOENT); 999 } 1000 } else 1001 vn_lock(*vpp, LK_DOWNGRADE | LK_RETRY); 1002 } 1003 return (-1); 1004 } 1005 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 1006 counter_u64_add(dotdothits, 1); 1007 dvlp2 = NULL; 1008 mtx_lock(dvlp); 1009 retry_dotdot: 1010 ncp = dvp->v_cache_dd; 1011 if (ncp == NULL) { 1012 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, 1013 "..", NULL); 1014 mtx_unlock(dvlp); 1015 return (0); 1016 } 1017 if ((cnp->cn_flags & MAKEENTRY) == 0) { 1018 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) { 1019 if (ncp->nc_dvp != dvp) 1020 panic("dvp %p v_cache_dd %p\n", dvp, ncp); 1021 if (!cache_zap_locked_vnode_kl2(ncp, 1022 dvp, &dvlp2)) 1023 goto retry_dotdot; 1024 MPASS(dvp->v_cache_dd == NULL); 1025 mtx_unlock(dvlp); 1026 if (dvlp2 != NULL) 1027 mtx_unlock(dvlp2); 1028 cache_free(ncp); 1029 } else { 1030 dvp->v_cache_dd = NULL; 1031 mtx_unlock(dvlp); 1032 if (dvlp2 != NULL) 1033 mtx_unlock(dvlp2); 1034 } 1035 return (0); 1036 } 1037 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) 1038 *vpp = ncp->nc_vp; 1039 else 1040 *vpp = ncp->nc_dvp; 1041 /* Return failure if negative entry was found. */ 1042 if (*vpp == NULL) 1043 goto negative_success; 1044 CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..", 1045 dvp, cnp->cn_nameptr, *vpp); 1046 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, "..", 1047 *vpp); 1048 cache_out_ts(ncp, tsp, ticksp); 1049 if ((ncp->nc_flag & (NCF_ISDOTDOT | NCF_DTS)) == 1050 NCF_DTS && tsp != NULL) 1051 *tsp = ((struct namecache_ts *)ncp)-> 1052 nc_dotdottime; 1053 goto success; 1054 } 1055 } 1056 1057 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp); 1058 blp = HASH2BUCKETLOCK(hash); 1059 rw_rlock(blp); 1060 1061 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 1062 counter_u64_add(numchecks, 1); 1063 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 1064 !bcmp(nc_get_name(ncp), cnp->cn_nameptr, ncp->nc_nlen)) 1065 break; 1066 } 1067 1068 /* We failed to find an entry */ 1069 if (ncp == NULL) { 1070 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr, 1071 NULL); 1072 if ((cnp->cn_flags & MAKEENTRY) == 0) { 1073 counter_u64_add(nummisszap, 1); 1074 } else { 1075 counter_u64_add(nummiss, 1); 1076 } 1077 goto unlock; 1078 } 1079 1080 /* We don't want to have an entry, so dump it */ 1081 if ((cnp->cn_flags & MAKEENTRY) == 0) { 1082 counter_u64_add(numposzaps, 1); 1083 goto zap_and_exit; 1084 } 1085 1086 /* We found a "positive" match, return the vnode */ 1087 if (ncp->nc_vp) { 1088 counter_u64_add(numposhits, 1); 1089 *vpp = ncp->nc_vp; 1090 CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p", 1091 dvp, cnp->cn_nameptr, *vpp, ncp); 1092 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, nc_get_name(ncp), 1093 *vpp); 1094 cache_out_ts(ncp, tsp, ticksp); 1095 goto success; 1096 } 1097 1098 negative_success: 1099 /* We found a negative match, and want to create it, so purge */ 1100 if (cnp->cn_nameiop == CREATE) { 1101 counter_u64_add(numnegzaps, 1); 1102 goto zap_and_exit; 1103 } 1104 1105 counter_u64_add(numneghits, 1); 1106 cache_negative_hit(ncp); 1107 if (ncp->nc_flag & NCF_WHITE) 1108 cnp->cn_flags |= ISWHITEOUT; 1109 SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp, 1110 nc_get_name(ncp)); 1111 cache_out_ts(ncp, tsp, ticksp); 1112 cache_lookup_unlock(blp, dvlp); 1113 return (ENOENT); 1114 1115 success: 1116 /* 1117 * On success we return a locked and ref'd vnode as per the lookup 1118 * protocol. 1119 */ 1120 MPASS(dvp != *vpp); 1121 ltype = 0; /* silence gcc warning */ 1122 if (cnp->cn_flags & ISDOTDOT) { 1123 ltype = VOP_ISLOCKED(dvp); 1124 VOP_UNLOCK(dvp, 0); 1125 } 1126 vhold(*vpp); 1127 cache_lookup_unlock(blp, dvlp); 1128 error = vget(*vpp, cnp->cn_lkflags | LK_VNHELD, cnp->cn_thread); 1129 if (cnp->cn_flags & ISDOTDOT) { 1130 vn_lock(dvp, ltype | LK_RETRY); 1131 if (dvp->v_iflag & VI_DOOMED) { 1132 if (error == 0) 1133 vput(*vpp); 1134 *vpp = NULL; 1135 return (ENOENT); 1136 } 1137 } 1138 if (error) { 1139 *vpp = NULL; 1140 goto retry; 1141 } 1142 if ((cnp->cn_flags & ISLASTCN) && 1143 (cnp->cn_lkflags & LK_TYPE_MASK) == LK_EXCLUSIVE) { 1144 ASSERT_VOP_ELOCKED(*vpp, "cache_lookup"); 1145 } 1146 return (-1); 1147 1148 unlock: 1149 cache_lookup_unlock(blp, dvlp); 1150 return (0); 1151 1152 zap_and_exit: 1153 if (blp != NULL) 1154 error = cache_zap_rlocked_bucket(ncp, blp); 1155 else 1156 error = cache_zap_locked_vnode(ncp, dvp); 1157 if (error != 0) { 1158 zap_and_exit_bucket_fail++; 1159 cache_maybe_yield(); 1160 goto retry; 1161 } 1162 cache_free(ncp); 1163 return (0); 1164 } 1165 1166 struct celockstate { 1167 struct mtx *vlp[3]; 1168 struct rwlock *blp[2]; 1169 }; 1170 CTASSERT((nitems(((struct celockstate *)0)->vlp) == 3)); 1171 CTASSERT((nitems(((struct celockstate *)0)->blp) == 2)); 1172 1173 static inline void 1174 cache_celockstate_init(struct celockstate *cel) 1175 { 1176 1177 bzero(cel, sizeof(*cel)); 1178 } 1179 1180 static void 1181 cache_lock_vnodes_cel(struct celockstate *cel, struct vnode *vp, 1182 struct vnode *dvp) 1183 { 1184 struct mtx *vlp1, *vlp2; 1185 1186 MPASS(cel->vlp[0] == NULL); 1187 MPASS(cel->vlp[1] == NULL); 1188 MPASS(cel->vlp[2] == NULL); 1189 1190 MPASS(vp != NULL || dvp != NULL); 1191 1192 vlp1 = VP2VNODELOCK(vp); 1193 vlp2 = VP2VNODELOCK(dvp); 1194 cache_sort(&vlp1, &vlp2); 1195 1196 if (vlp1 != NULL) { 1197 mtx_lock(vlp1); 1198 cel->vlp[0] = vlp1; 1199 } 1200 mtx_lock(vlp2); 1201 cel->vlp[1] = vlp2; 1202 } 1203 1204 static void 1205 cache_unlock_vnodes_cel(struct celockstate *cel) 1206 { 1207 1208 MPASS(cel->vlp[0] != NULL || cel->vlp[1] != NULL); 1209 1210 if (cel->vlp[0] != NULL) 1211 mtx_unlock(cel->vlp[0]); 1212 if (cel->vlp[1] != NULL) 1213 mtx_unlock(cel->vlp[1]); 1214 if (cel->vlp[2] != NULL) 1215 mtx_unlock(cel->vlp[2]); 1216 } 1217 1218 static bool 1219 cache_lock_vnodes_cel_3(struct celockstate *cel, struct vnode *vp) 1220 { 1221 struct mtx *vlp; 1222 bool ret; 1223 1224 cache_assert_vlp_locked(cel->vlp[0]); 1225 cache_assert_vlp_locked(cel->vlp[1]); 1226 MPASS(cel->vlp[2] == NULL); 1227 1228 vlp = VP2VNODELOCK(vp); 1229 if (vlp == NULL) 1230 return (true); 1231 1232 ret = true; 1233 if (vlp >= cel->vlp[1]) { 1234 mtx_lock(vlp); 1235 } else { 1236 if (mtx_trylock(vlp)) 1237 goto out; 1238 cache_lock_vnodes_cel_3_failures++; 1239 cache_unlock_vnodes_cel(cel); 1240 if (vlp < cel->vlp[0]) { 1241 mtx_lock(vlp); 1242 mtx_lock(cel->vlp[0]); 1243 mtx_lock(cel->vlp[1]); 1244 } else { 1245 if (cel->vlp[0] != NULL) 1246 mtx_lock(cel->vlp[0]); 1247 mtx_lock(vlp); 1248 mtx_lock(cel->vlp[1]); 1249 } 1250 ret = false; 1251 } 1252 out: 1253 cel->vlp[2] = vlp; 1254 return (ret); 1255 } 1256 1257 static void 1258 cache_lock_buckets_cel(struct celockstate *cel, struct rwlock *blp1, 1259 struct rwlock *blp2) 1260 { 1261 1262 MPASS(cel->blp[0] == NULL); 1263 MPASS(cel->blp[1] == NULL); 1264 1265 cache_sort(&blp1, &blp2); 1266 1267 if (blp1 != NULL) { 1268 rw_wlock(blp1); 1269 cel->blp[0] = blp1; 1270 } 1271 rw_wlock(blp2); 1272 cel->blp[1] = blp2; 1273 } 1274 1275 static void 1276 cache_unlock_buckets_cel(struct celockstate *cel) 1277 { 1278 1279 if (cel->blp[0] != NULL) 1280 rw_wunlock(cel->blp[0]); 1281 rw_wunlock(cel->blp[1]); 1282 } 1283 1284 /* 1285 * Lock part of the cache affected by the insertion. 1286 * 1287 * This means vnodelocks for dvp, vp and the relevant bucketlock. 1288 * However, insertion can result in removal of an old entry. In this 1289 * case we have an additional vnode and bucketlock pair to lock. If the 1290 * entry is negative, ncelock is locked instead of the vnode. 1291 * 1292 * That is, in the worst case we have to lock 3 vnodes and 2 bucketlocks, while 1293 * preserving the locking order (smaller address first). 1294 */ 1295 static void 1296 cache_enter_lock(struct celockstate *cel, struct vnode *dvp, struct vnode *vp, 1297 uint32_t hash) 1298 { 1299 struct namecache *ncp; 1300 struct rwlock *blps[2]; 1301 1302 blps[0] = HASH2BUCKETLOCK(hash); 1303 for (;;) { 1304 blps[1] = NULL; 1305 cache_lock_vnodes_cel(cel, dvp, vp); 1306 if (vp == NULL || vp->v_type != VDIR) 1307 break; 1308 ncp = vp->v_cache_dd; 1309 if (ncp == NULL) 1310 break; 1311 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 1312 break; 1313 MPASS(ncp->nc_dvp == vp); 1314 blps[1] = NCP2BUCKETLOCK(ncp); 1315 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp)) 1316 break; 1317 /* 1318 * All vnodes got re-locked. Re-validate the state and if 1319 * nothing changed we are done. Otherwise restart. 1320 */ 1321 if (ncp == vp->v_cache_dd && 1322 (ncp->nc_flag & NCF_ISDOTDOT) != 0 && 1323 blps[1] == NCP2BUCKETLOCK(ncp) && 1324 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2]) 1325 break; 1326 cache_unlock_vnodes_cel(cel); 1327 cel->vlp[0] = NULL; 1328 cel->vlp[1] = NULL; 1329 cel->vlp[2] = NULL; 1330 } 1331 cache_lock_buckets_cel(cel, blps[0], blps[1]); 1332 } 1333 1334 static void 1335 cache_enter_lock_dd(struct celockstate *cel, struct vnode *dvp, struct vnode *vp, 1336 uint32_t hash) 1337 { 1338 struct namecache *ncp; 1339 struct rwlock *blps[2]; 1340 1341 blps[0] = HASH2BUCKETLOCK(hash); 1342 for (;;) { 1343 blps[1] = NULL; 1344 cache_lock_vnodes_cel(cel, dvp, vp); 1345 ncp = dvp->v_cache_dd; 1346 if (ncp == NULL) 1347 break; 1348 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 1349 break; 1350 MPASS(ncp->nc_dvp == dvp); 1351 blps[1] = NCP2BUCKETLOCK(ncp); 1352 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp)) 1353 break; 1354 if (ncp == dvp->v_cache_dd && 1355 (ncp->nc_flag & NCF_ISDOTDOT) != 0 && 1356 blps[1] == NCP2BUCKETLOCK(ncp) && 1357 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2]) 1358 break; 1359 cache_unlock_vnodes_cel(cel); 1360 cel->vlp[0] = NULL; 1361 cel->vlp[1] = NULL; 1362 cel->vlp[2] = NULL; 1363 } 1364 cache_lock_buckets_cel(cel, blps[0], blps[1]); 1365 } 1366 1367 static void 1368 cache_enter_unlock(struct celockstate *cel) 1369 { 1370 1371 cache_unlock_buckets_cel(cel); 1372 cache_unlock_vnodes_cel(cel); 1373 } 1374 1375 /* 1376 * Add an entry to the cache. 1377 */ 1378 void 1379 cache_enter_time(struct vnode *dvp, struct vnode *vp, struct componentname *cnp, 1380 struct timespec *tsp, struct timespec *dtsp) 1381 { 1382 struct celockstate cel; 1383 struct namecache *ncp, *n2, *ndd; 1384 struct namecache_ts *n3; 1385 struct nchashhead *ncpp; 1386 uint32_t hash; 1387 int flag; 1388 int len; 1389 1390 CTR3(KTR_VFS, "cache_enter(%p, %p, %s)", dvp, vp, cnp->cn_nameptr); 1391 VNASSERT(vp == NULL || (vp->v_iflag & VI_DOOMED) == 0, vp, 1392 ("cache_enter: Adding a doomed vnode")); 1393 VNASSERT(dvp == NULL || (dvp->v_iflag & VI_DOOMED) == 0, dvp, 1394 ("cache_enter: Doomed vnode used as src")); 1395 1396 if (!doingcache) 1397 return; 1398 1399 /* 1400 * Avoid blowout in namecache entries. 1401 */ 1402 if (numcache >= desiredvnodes * ncsizefactor) 1403 return; 1404 1405 cache_celockstate_init(&cel); 1406 ndd = NULL; 1407 flag = 0; 1408 if (cnp->cn_nameptr[0] == '.') { 1409 if (cnp->cn_namelen == 1) 1410 return; 1411 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 1412 len = cnp->cn_namelen; 1413 hash = cache_get_hash(cnp->cn_nameptr, len, dvp); 1414 cache_enter_lock_dd(&cel, dvp, vp, hash); 1415 /* 1416 * If dotdot entry already exists, just retarget it 1417 * to new parent vnode, otherwise continue with new 1418 * namecache entry allocation. 1419 */ 1420 if ((ncp = dvp->v_cache_dd) != NULL && 1421 ncp->nc_flag & NCF_ISDOTDOT) { 1422 KASSERT(ncp->nc_dvp == dvp, 1423 ("wrong isdotdot parent")); 1424 if (ncp->nc_vp != NULL) { 1425 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, 1426 ncp, nc_dst); 1427 } else { 1428 cache_negative_remove(ncp, false); 1429 } 1430 if (vp != NULL) { 1431 TAILQ_INSERT_HEAD(&vp->v_cache_dst, 1432 ncp, nc_dst); 1433 } else { 1434 cache_negative_insert(ncp); 1435 } 1436 ncp->nc_vp = vp; 1437 cache_enter_unlock(&cel); 1438 return; 1439 } 1440 dvp->v_cache_dd = NULL; 1441 cache_enter_unlock(&cel); 1442 cache_celockstate_init(&cel); 1443 SDT_PROBE3(vfs, namecache, enter, done, dvp, "..", vp); 1444 flag = NCF_ISDOTDOT; 1445 } 1446 } 1447 1448 /* 1449 * Calculate the hash key and setup as much of the new 1450 * namecache entry as possible before acquiring the lock. 1451 */ 1452 ncp = cache_alloc(cnp->cn_namelen, tsp != NULL); 1453 ncp->nc_vp = vp; 1454 ncp->nc_dvp = dvp; 1455 ncp->nc_flag = flag; 1456 if (tsp != NULL) { 1457 n3 = (struct namecache_ts *)ncp; 1458 n3->nc_time = *tsp; 1459 n3->nc_ticks = ticks; 1460 n3->nc_flag |= NCF_TS; 1461 if (dtsp != NULL) { 1462 n3->nc_dotdottime = *dtsp; 1463 n3->nc_flag |= NCF_DTS; 1464 } 1465 } 1466 len = ncp->nc_nlen = cnp->cn_namelen; 1467 hash = cache_get_hash(cnp->cn_nameptr, len, dvp); 1468 strlcpy(nc_get_name(ncp), cnp->cn_nameptr, len + 1); 1469 cache_enter_lock(&cel, dvp, vp, hash); 1470 1471 /* 1472 * See if this vnode or negative entry is already in the cache 1473 * with this name. This can happen with concurrent lookups of 1474 * the same path name. 1475 */ 1476 ncpp = NCHHASH(hash); 1477 LIST_FOREACH(n2, ncpp, nc_hash) { 1478 if (n2->nc_dvp == dvp && 1479 n2->nc_nlen == cnp->cn_namelen && 1480 !bcmp(nc_get_name(n2), cnp->cn_nameptr, n2->nc_nlen)) { 1481 if (tsp != NULL) { 1482 KASSERT((n2->nc_flag & NCF_TS) != 0, 1483 ("no NCF_TS")); 1484 n3 = (struct namecache_ts *)n2; 1485 n3->nc_time = 1486 ((struct namecache_ts *)ncp)->nc_time; 1487 n3->nc_ticks = 1488 ((struct namecache_ts *)ncp)->nc_ticks; 1489 if (dtsp != NULL) { 1490 n3->nc_dotdottime = 1491 ((struct namecache_ts *)ncp)-> 1492 nc_dotdottime; 1493 n3->nc_flag |= NCF_DTS; 1494 } 1495 } 1496 goto out_unlock_free; 1497 } 1498 } 1499 1500 if (flag == NCF_ISDOTDOT) { 1501 /* 1502 * See if we are trying to add .. entry, but some other lookup 1503 * has populated v_cache_dd pointer already. 1504 */ 1505 if (dvp->v_cache_dd != NULL) 1506 goto out_unlock_free; 1507 KASSERT(vp == NULL || vp->v_type == VDIR, 1508 ("wrong vnode type %p", vp)); 1509 dvp->v_cache_dd = ncp; 1510 } 1511 1512 atomic_add_rel_long(&numcache, 1); 1513 if (vp != NULL) { 1514 if (vp->v_type == VDIR) { 1515 if (flag != NCF_ISDOTDOT) { 1516 /* 1517 * For this case, the cache entry maps both the 1518 * directory name in it and the name ".." for the 1519 * directory's parent. 1520 */ 1521 if ((ndd = vp->v_cache_dd) != NULL) { 1522 if ((ndd->nc_flag & NCF_ISDOTDOT) != 0) 1523 cache_zap_locked(ndd, false); 1524 else 1525 ndd = NULL; 1526 } 1527 vp->v_cache_dd = ncp; 1528 } 1529 } else { 1530 vp->v_cache_dd = NULL; 1531 } 1532 } 1533 1534 if (flag != NCF_ISDOTDOT) { 1535 if (LIST_EMPTY(&dvp->v_cache_src)) { 1536 vhold(dvp); 1537 atomic_add_rel_long(&numcachehv, 1); 1538 } 1539 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); 1540 } 1541 1542 /* 1543 * Insert the new namecache entry into the appropriate chain 1544 * within the cache entries table. 1545 */ 1546 LIST_INSERT_HEAD(ncpp, ncp, nc_hash); 1547 1548 /* 1549 * If the entry is "negative", we place it into the 1550 * "negative" cache queue, otherwise, we place it into the 1551 * destination vnode's cache entries queue. 1552 */ 1553 if (vp != NULL) { 1554 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); 1555 SDT_PROBE3(vfs, namecache, enter, done, dvp, nc_get_name(ncp), 1556 vp); 1557 } else { 1558 if (cnp->cn_flags & ISWHITEOUT) 1559 ncp->nc_flag |= NCF_WHITE; 1560 cache_negative_insert(ncp); 1561 SDT_PROBE2(vfs, namecache, enter_negative, done, dvp, 1562 nc_get_name(ncp)); 1563 } 1564 cache_enter_unlock(&cel); 1565 if (numneg * ncnegfactor > numcache) 1566 cache_negative_zap_one(); 1567 cache_free(ndd); 1568 return; 1569 out_unlock_free: 1570 cache_enter_unlock(&cel); 1571 cache_free(ncp); 1572 return; 1573 } 1574 1575 static u_int 1576 cache_roundup_2(u_int val) 1577 { 1578 u_int res; 1579 1580 for (res = 1; res <= val; res <<= 1) 1581 continue; 1582 1583 return (res); 1584 } 1585 1586 /* 1587 * Name cache initialization, from vfs_init() when we are booting 1588 */ 1589 static void 1590 nchinit(void *dummy __unused) 1591 { 1592 u_int i; 1593 1594 TAILQ_INIT(&ncneg); 1595 1596 cache_zone_small = uma_zcreate("S VFS Cache", 1597 sizeof(struct namecache) + CACHE_PATH_CUTOFF + 1, 1598 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 1599 cache_zone_small_ts = uma_zcreate("STS VFS Cache", 1600 sizeof(struct namecache_ts) + CACHE_PATH_CUTOFF + 1, 1601 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 1602 cache_zone_large = uma_zcreate("L VFS Cache", 1603 sizeof(struct namecache) + NAME_MAX + 1, 1604 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 1605 cache_zone_large_ts = uma_zcreate("LTS VFS Cache", 1606 sizeof(struct namecache_ts) + NAME_MAX + 1, 1607 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 1608 1609 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash); 1610 numbucketlocks = cache_roundup_2(mp_ncpus * 64); 1611 bucketlocks = malloc(sizeof(*bucketlocks) * numbucketlocks, M_VFSCACHE, 1612 M_WAITOK | M_ZERO); 1613 for (i = 0; i < numbucketlocks; i++) 1614 rw_init_flags(&bucketlocks[i], "ncbuc", RW_DUPOK | RW_RECURSE); 1615 numvnodelocks = cache_roundup_2(mp_ncpus * 64); 1616 vnodelocks = malloc(sizeof(*vnodelocks) * numvnodelocks, M_VFSCACHE, 1617 M_WAITOK | M_ZERO); 1618 for (i = 0; i < numvnodelocks; i++) 1619 mtx_init(&vnodelocks[i], "ncvn", NULL, MTX_DUPOK | MTX_RECURSE); 1620 ncpurgeminvnodes = numbucketlocks; 1621 1622 numcalls = counter_u64_alloc(M_WAITOK); 1623 dothits = counter_u64_alloc(M_WAITOK); 1624 dotdothits = counter_u64_alloc(M_WAITOK); 1625 numchecks = counter_u64_alloc(M_WAITOK); 1626 nummiss = counter_u64_alloc(M_WAITOK); 1627 nummisszap = counter_u64_alloc(M_WAITOK); 1628 numposzaps = counter_u64_alloc(M_WAITOK); 1629 numposhits = counter_u64_alloc(M_WAITOK); 1630 numnegzaps = counter_u64_alloc(M_WAITOK); 1631 numneghits = counter_u64_alloc(M_WAITOK); 1632 numfullpathcalls = counter_u64_alloc(M_WAITOK); 1633 numfullpathfail1 = counter_u64_alloc(M_WAITOK); 1634 numfullpathfail2 = counter_u64_alloc(M_WAITOK); 1635 numfullpathfail4 = counter_u64_alloc(M_WAITOK); 1636 numfullpathfound = counter_u64_alloc(M_WAITOK); 1637 } 1638 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL); 1639 1640 void 1641 cache_changesize(int newmaxvnodes) 1642 { 1643 struct nchashhead *new_nchashtbl, *old_nchashtbl; 1644 u_long new_nchash, old_nchash; 1645 struct namecache *ncp; 1646 uint32_t hash; 1647 int i; 1648 1649 new_nchashtbl = hashinit(newmaxvnodes * 2, M_VFSCACHE, &new_nchash); 1650 /* If same hash table size, nothing to do */ 1651 if (nchash == new_nchash) { 1652 free(new_nchashtbl, M_VFSCACHE); 1653 return; 1654 } 1655 /* 1656 * Move everything from the old hash table to the new table. 1657 * None of the namecache entries in the table can be removed 1658 * because to do so, they have to be removed from the hash table. 1659 */ 1660 cache_lock_all_vnodes(); 1661 cache_lock_all_buckets(); 1662 old_nchashtbl = nchashtbl; 1663 old_nchash = nchash; 1664 nchashtbl = new_nchashtbl; 1665 nchash = new_nchash; 1666 for (i = 0; i <= old_nchash; i++) { 1667 while ((ncp = LIST_FIRST(&old_nchashtbl[i])) != NULL) { 1668 hash = cache_get_hash(nc_get_name(ncp), ncp->nc_nlen, 1669 ncp->nc_dvp); 1670 LIST_REMOVE(ncp, nc_hash); 1671 LIST_INSERT_HEAD(NCHHASH(hash), ncp, nc_hash); 1672 } 1673 } 1674 cache_unlock_all_buckets(); 1675 cache_unlock_all_vnodes(); 1676 free(old_nchashtbl, M_VFSCACHE); 1677 } 1678 1679 /* 1680 * Invalidate all entries to a particular vnode. 1681 */ 1682 void 1683 cache_purge(struct vnode *vp) 1684 { 1685 TAILQ_HEAD(, namecache) ncps; 1686 struct namecache *ncp, *nnp; 1687 struct mtx *vlp, *vlp2; 1688 1689 CTR1(KTR_VFS, "cache_purge(%p)", vp); 1690 SDT_PROBE1(vfs, namecache, purge, done, vp); 1691 if (LIST_EMPTY(&vp->v_cache_src) && TAILQ_EMPTY(&vp->v_cache_dst) && 1692 vp->v_cache_dd == NULL) 1693 return; 1694 TAILQ_INIT(&ncps); 1695 vlp = VP2VNODELOCK(vp); 1696 vlp2 = NULL; 1697 mtx_lock(vlp); 1698 retry: 1699 while (!LIST_EMPTY(&vp->v_cache_src)) { 1700 ncp = LIST_FIRST(&vp->v_cache_src); 1701 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 1702 goto retry; 1703 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 1704 } 1705 while (!TAILQ_EMPTY(&vp->v_cache_dst)) { 1706 ncp = TAILQ_FIRST(&vp->v_cache_dst); 1707 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 1708 goto retry; 1709 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 1710 } 1711 ncp = vp->v_cache_dd; 1712 if (ncp != NULL) { 1713 KASSERT(ncp->nc_flag & NCF_ISDOTDOT, 1714 ("lost dotdot link")); 1715 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 1716 goto retry; 1717 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 1718 } 1719 KASSERT(vp->v_cache_dd == NULL, ("incomplete purge")); 1720 mtx_unlock(vlp); 1721 if (vlp2 != NULL) 1722 mtx_unlock(vlp2); 1723 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { 1724 cache_free(ncp); 1725 } 1726 } 1727 1728 /* 1729 * Invalidate all negative entries for a particular directory vnode. 1730 */ 1731 void 1732 cache_purge_negative(struct vnode *vp) 1733 { 1734 TAILQ_HEAD(, namecache) ncps; 1735 struct namecache *ncp, *nnp; 1736 struct mtx *vlp; 1737 1738 CTR1(KTR_VFS, "cache_purge_negative(%p)", vp); 1739 SDT_PROBE1(vfs, namecache, purge_negative, done, vp); 1740 TAILQ_INIT(&ncps); 1741 vlp = VP2VNODELOCK(vp); 1742 mtx_lock(vlp); 1743 LIST_FOREACH_SAFE(ncp, &vp->v_cache_src, nc_src, nnp) { 1744 if (ncp->nc_vp != NULL) 1745 continue; 1746 cache_zap_negative_locked_vnode_kl(ncp, vp); 1747 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst); 1748 } 1749 mtx_unlock(vlp); 1750 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { 1751 cache_free(ncp); 1752 } 1753 } 1754 1755 /* 1756 * Flush all entries referencing a particular filesystem. 1757 */ 1758 void 1759 cache_purgevfs(struct mount *mp, bool force) 1760 { 1761 TAILQ_HEAD(, namecache) ncps; 1762 struct mtx *vlp1, *vlp2; 1763 struct rwlock *blp; 1764 struct nchashhead *bucket; 1765 struct namecache *ncp, *nnp; 1766 u_long i, j, n_nchash; 1767 int error; 1768 1769 /* Scan hash tables for applicable entries */ 1770 SDT_PROBE1(vfs, namecache, purgevfs, done, mp); 1771 if (!force && mp->mnt_nvnodelistsize <= ncpurgeminvnodes) 1772 return; 1773 TAILQ_INIT(&ncps); 1774 n_nchash = nchash + 1; 1775 vlp1 = vlp2 = NULL; 1776 for (i = 0; i < numbucketlocks; i++) { 1777 blp = (struct rwlock *)&bucketlocks[i]; 1778 rw_wlock(blp); 1779 for (j = i; j < n_nchash; j += numbucketlocks) { 1780 retry: 1781 bucket = &nchashtbl[j]; 1782 LIST_FOREACH_SAFE(ncp, bucket, nc_hash, nnp) { 1783 cache_assert_bucket_locked(ncp, RA_WLOCKED); 1784 if (ncp->nc_dvp->v_mount != mp) 1785 continue; 1786 error = cache_zap_wlocked_bucket_kl(ncp, blp, 1787 &vlp1, &vlp2); 1788 if (error != 0) 1789 goto retry; 1790 TAILQ_INSERT_HEAD(&ncps, ncp, nc_dst); 1791 } 1792 } 1793 rw_wunlock(blp); 1794 if (vlp1 == NULL && vlp2 == NULL) 1795 cache_maybe_yield(); 1796 } 1797 if (vlp1 != NULL) 1798 mtx_unlock(vlp1); 1799 if (vlp2 != NULL) 1800 mtx_unlock(vlp2); 1801 1802 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) { 1803 cache_free(ncp); 1804 } 1805 } 1806 1807 /* 1808 * Perform canonical checks and cache lookup and pass on to filesystem 1809 * through the vop_cachedlookup only if needed. 1810 */ 1811 1812 int 1813 vfs_cache_lookup(struct vop_lookup_args *ap) 1814 { 1815 struct vnode *dvp; 1816 int error; 1817 struct vnode **vpp = ap->a_vpp; 1818 struct componentname *cnp = ap->a_cnp; 1819 struct ucred *cred = cnp->cn_cred; 1820 int flags = cnp->cn_flags; 1821 struct thread *td = cnp->cn_thread; 1822 1823 *vpp = NULL; 1824 dvp = ap->a_dvp; 1825 1826 if (dvp->v_type != VDIR) 1827 return (ENOTDIR); 1828 1829 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && 1830 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 1831 return (EROFS); 1832 1833 error = VOP_ACCESS(dvp, VEXEC, cred, td); 1834 if (error) 1835 return (error); 1836 1837 error = cache_lookup(dvp, vpp, cnp, NULL, NULL); 1838 if (error == 0) 1839 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); 1840 if (error == -1) 1841 return (0); 1842 return (error); 1843 } 1844 1845 /* 1846 * XXX All of these sysctls would probably be more productive dead. 1847 */ 1848 static int disablecwd; 1849 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, 1850 "Disable the getcwd syscall"); 1851 1852 /* Implementation of the getcwd syscall. */ 1853 int 1854 sys___getcwd(struct thread *td, struct __getcwd_args *uap) 1855 { 1856 1857 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen, 1858 MAXPATHLEN)); 1859 } 1860 1861 int 1862 kern___getcwd(struct thread *td, char *buf, enum uio_seg bufseg, u_int buflen, 1863 u_int path_max) 1864 { 1865 char *bp, *tmpbuf; 1866 struct filedesc *fdp; 1867 struct vnode *cdir, *rdir; 1868 int error; 1869 1870 if (disablecwd) 1871 return (ENODEV); 1872 if (buflen < 2) 1873 return (EINVAL); 1874 if (buflen > path_max) 1875 buflen = path_max; 1876 1877 tmpbuf = malloc(buflen, M_TEMP, M_WAITOK); 1878 fdp = td->td_proc->p_fd; 1879 FILEDESC_SLOCK(fdp); 1880 cdir = fdp->fd_cdir; 1881 VREF(cdir); 1882 rdir = fdp->fd_rdir; 1883 VREF(rdir); 1884 FILEDESC_SUNLOCK(fdp); 1885 error = vn_fullpath1(td, cdir, rdir, tmpbuf, &bp, buflen); 1886 vrele(rdir); 1887 vrele(cdir); 1888 1889 if (!error) { 1890 if (bufseg == UIO_SYSSPACE) 1891 bcopy(bp, buf, strlen(bp) + 1); 1892 else 1893 error = copyout(bp, buf, strlen(bp) + 1); 1894 #ifdef KTRACE 1895 if (KTRPOINT(curthread, KTR_NAMEI)) 1896 ktrnamei(bp); 1897 #endif 1898 } 1899 free(tmpbuf, M_TEMP); 1900 return (error); 1901 } 1902 1903 /* 1904 * Thus begins the fullpath magic. 1905 */ 1906 1907 static int disablefullpath; 1908 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0, 1909 "Disable the vn_fullpath function"); 1910 1911 /* 1912 * Retrieve the full filesystem path that correspond to a vnode from the name 1913 * cache (if available) 1914 */ 1915 int 1916 vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf) 1917 { 1918 char *buf; 1919 struct filedesc *fdp; 1920 struct vnode *rdir; 1921 int error; 1922 1923 if (disablefullpath) 1924 return (ENODEV); 1925 if (vn == NULL) 1926 return (EINVAL); 1927 1928 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 1929 fdp = td->td_proc->p_fd; 1930 FILEDESC_SLOCK(fdp); 1931 rdir = fdp->fd_rdir; 1932 VREF(rdir); 1933 FILEDESC_SUNLOCK(fdp); 1934 error = vn_fullpath1(td, vn, rdir, buf, retbuf, MAXPATHLEN); 1935 vrele(rdir); 1936 1937 if (!error) 1938 *freebuf = buf; 1939 else 1940 free(buf, M_TEMP); 1941 return (error); 1942 } 1943 1944 /* 1945 * This function is similar to vn_fullpath, but it attempts to lookup the 1946 * pathname relative to the global root mount point. This is required for the 1947 * auditing sub-system, as audited pathnames must be absolute, relative to the 1948 * global root mount point. 1949 */ 1950 int 1951 vn_fullpath_global(struct thread *td, struct vnode *vn, 1952 char **retbuf, char **freebuf) 1953 { 1954 char *buf; 1955 int error; 1956 1957 if (disablefullpath) 1958 return (ENODEV); 1959 if (vn == NULL) 1960 return (EINVAL); 1961 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 1962 error = vn_fullpath1(td, vn, rootvnode, buf, retbuf, MAXPATHLEN); 1963 if (!error) 1964 *freebuf = buf; 1965 else 1966 free(buf, M_TEMP); 1967 return (error); 1968 } 1969 1970 int 1971 vn_vptocnp(struct vnode **vp, struct ucred *cred, char *buf, u_int *buflen) 1972 { 1973 struct vnode *dvp; 1974 struct namecache *ncp; 1975 struct mtx *vlp; 1976 int error; 1977 1978 vlp = VP2VNODELOCK(*vp); 1979 mtx_lock(vlp); 1980 TAILQ_FOREACH(ncp, &((*vp)->v_cache_dst), nc_dst) { 1981 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 1982 break; 1983 } 1984 if (ncp != NULL) { 1985 if (*buflen < ncp->nc_nlen) { 1986 mtx_unlock(vlp); 1987 vrele(*vp); 1988 counter_u64_add(numfullpathfail4, 1); 1989 error = ENOMEM; 1990 SDT_PROBE3(vfs, namecache, fullpath, return, error, 1991 vp, NULL); 1992 return (error); 1993 } 1994 *buflen -= ncp->nc_nlen; 1995 memcpy(buf + *buflen, nc_get_name(ncp), ncp->nc_nlen); 1996 SDT_PROBE3(vfs, namecache, fullpath, hit, ncp->nc_dvp, 1997 nc_get_name(ncp), vp); 1998 dvp = *vp; 1999 *vp = ncp->nc_dvp; 2000 vref(*vp); 2001 mtx_unlock(vlp); 2002 vrele(dvp); 2003 return (0); 2004 } 2005 SDT_PROBE1(vfs, namecache, fullpath, miss, vp); 2006 2007 mtx_unlock(vlp); 2008 vn_lock(*vp, LK_SHARED | LK_RETRY); 2009 error = VOP_VPTOCNP(*vp, &dvp, cred, buf, buflen); 2010 vput(*vp); 2011 if (error) { 2012 counter_u64_add(numfullpathfail2, 1); 2013 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); 2014 return (error); 2015 } 2016 2017 *vp = dvp; 2018 if (dvp->v_iflag & VI_DOOMED) { 2019 /* forced unmount */ 2020 vrele(dvp); 2021 error = ENOENT; 2022 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); 2023 return (error); 2024 } 2025 /* 2026 * *vp has its use count incremented still. 2027 */ 2028 2029 return (0); 2030 } 2031 2032 /* 2033 * The magic behind kern___getcwd() and vn_fullpath(). 2034 */ 2035 static int 2036 vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 2037 char *buf, char **retbuf, u_int buflen) 2038 { 2039 int error, slash_prefixed; 2040 #ifdef KDTRACE_HOOKS 2041 struct vnode *startvp = vp; 2042 #endif 2043 struct vnode *vp1; 2044 2045 buflen--; 2046 buf[buflen] = '\0'; 2047 error = 0; 2048 slash_prefixed = 0; 2049 2050 SDT_PROBE1(vfs, namecache, fullpath, entry, vp); 2051 counter_u64_add(numfullpathcalls, 1); 2052 vref(vp); 2053 if (vp->v_type != VDIR) { 2054 error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen); 2055 if (error) 2056 return (error); 2057 if (buflen == 0) { 2058 vrele(vp); 2059 return (ENOMEM); 2060 } 2061 buf[--buflen] = '/'; 2062 slash_prefixed = 1; 2063 } 2064 while (vp != rdir && vp != rootvnode) { 2065 if (vp->v_vflag & VV_ROOT) { 2066 if (vp->v_iflag & VI_DOOMED) { /* forced unmount */ 2067 vrele(vp); 2068 error = ENOENT; 2069 SDT_PROBE3(vfs, namecache, fullpath, return, 2070 error, vp, NULL); 2071 break; 2072 } 2073 vp1 = vp->v_mount->mnt_vnodecovered; 2074 vref(vp1); 2075 vrele(vp); 2076 vp = vp1; 2077 continue; 2078 } 2079 if (vp->v_type != VDIR) { 2080 vrele(vp); 2081 counter_u64_add(numfullpathfail1, 1); 2082 error = ENOTDIR; 2083 SDT_PROBE3(vfs, namecache, fullpath, return, 2084 error, vp, NULL); 2085 break; 2086 } 2087 error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen); 2088 if (error) 2089 break; 2090 if (buflen == 0) { 2091 vrele(vp); 2092 error = ENOMEM; 2093 SDT_PROBE3(vfs, namecache, fullpath, return, error, 2094 startvp, NULL); 2095 break; 2096 } 2097 buf[--buflen] = '/'; 2098 slash_prefixed = 1; 2099 } 2100 if (error) 2101 return (error); 2102 if (!slash_prefixed) { 2103 if (buflen == 0) { 2104 vrele(vp); 2105 counter_u64_add(numfullpathfail4, 1); 2106 SDT_PROBE3(vfs, namecache, fullpath, return, ENOMEM, 2107 startvp, NULL); 2108 return (ENOMEM); 2109 } 2110 buf[--buflen] = '/'; 2111 } 2112 counter_u64_add(numfullpathfound, 1); 2113 vrele(vp); 2114 2115 SDT_PROBE3(vfs, namecache, fullpath, return, 0, startvp, buf + buflen); 2116 *retbuf = buf + buflen; 2117 return (0); 2118 } 2119 2120 struct vnode * 2121 vn_dir_dd_ino(struct vnode *vp) 2122 { 2123 struct namecache *ncp; 2124 struct vnode *ddvp; 2125 struct mtx *vlp; 2126 2127 ASSERT_VOP_LOCKED(vp, "vn_dir_dd_ino"); 2128 vlp = VP2VNODELOCK(vp); 2129 mtx_lock(vlp); 2130 TAILQ_FOREACH(ncp, &(vp->v_cache_dst), nc_dst) { 2131 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) 2132 continue; 2133 ddvp = ncp->nc_dvp; 2134 vhold(ddvp); 2135 mtx_unlock(vlp); 2136 if (vget(ddvp, LK_SHARED | LK_NOWAIT | LK_VNHELD, curthread)) 2137 return (NULL); 2138 return (ddvp); 2139 } 2140 mtx_unlock(vlp); 2141 return (NULL); 2142 } 2143 2144 int 2145 vn_commname(struct vnode *vp, char *buf, u_int buflen) 2146 { 2147 struct namecache *ncp; 2148 struct mtx *vlp; 2149 int l; 2150 2151 vlp = VP2VNODELOCK(vp); 2152 mtx_lock(vlp); 2153 TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst) 2154 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 2155 break; 2156 if (ncp == NULL) { 2157 mtx_unlock(vlp); 2158 return (ENOENT); 2159 } 2160 l = min(ncp->nc_nlen, buflen - 1); 2161 memcpy(buf, nc_get_name(ncp), l); 2162 mtx_unlock(vlp); 2163 buf[l] = '\0'; 2164 return (0); 2165 } 2166 2167 /* ABI compat shims for old kernel modules. */ 2168 #undef cache_enter 2169 2170 void cache_enter(struct vnode *dvp, struct vnode *vp, 2171 struct componentname *cnp); 2172 2173 void 2174 cache_enter(struct vnode *dvp, struct vnode *vp, struct componentname *cnp) 2175 { 2176 2177 cache_enter_time(dvp, vp, cnp, NULL, NULL); 2178 } 2179 2180 /* 2181 * This function updates path string to vnode's full global path 2182 * and checks the size of the new path string against the pathlen argument. 2183 * 2184 * Requires a locked, referenced vnode. 2185 * Vnode is re-locked on success or ENODEV, otherwise unlocked. 2186 * 2187 * If sysctl debug.disablefullpath is set, ENODEV is returned, 2188 * vnode is left locked and path remain untouched. 2189 * 2190 * If vp is a directory, the call to vn_fullpath_global() always succeeds 2191 * because it falls back to the ".." lookup if the namecache lookup fails. 2192 */ 2193 int 2194 vn_path_to_global_path(struct thread *td, struct vnode *vp, char *path, 2195 u_int pathlen) 2196 { 2197 struct nameidata nd; 2198 struct vnode *vp1; 2199 char *rpath, *fbuf; 2200 int error; 2201 2202 ASSERT_VOP_ELOCKED(vp, __func__); 2203 2204 /* Return ENODEV if sysctl debug.disablefullpath==1 */ 2205 if (disablefullpath) 2206 return (ENODEV); 2207 2208 /* Construct global filesystem path from vp. */ 2209 VOP_UNLOCK(vp, 0); 2210 error = vn_fullpath_global(td, vp, &rpath, &fbuf); 2211 2212 if (error != 0) { 2213 vrele(vp); 2214 return (error); 2215 } 2216 2217 if (strlen(rpath) >= pathlen) { 2218 vrele(vp); 2219 error = ENAMETOOLONG; 2220 goto out; 2221 } 2222 2223 /* 2224 * Re-lookup the vnode by path to detect a possible rename. 2225 * As a side effect, the vnode is relocked. 2226 * If vnode was renamed, return ENOENT. 2227 */ 2228 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1, 2229 UIO_SYSSPACE, path, td); 2230 error = namei(&nd); 2231 if (error != 0) { 2232 vrele(vp); 2233 goto out; 2234 } 2235 NDFREE(&nd, NDF_ONLY_PNBUF); 2236 vp1 = nd.ni_vp; 2237 vrele(vp); 2238 if (vp1 == vp) 2239 strcpy(path, rpath); 2240 else { 2241 vput(vp1); 2242 error = ENOENT; 2243 } 2244 2245 out: 2246 free(fbuf, M_TEMP); 2247 return (error); 2248 } 2249