1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1989, 1993, 1995 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Poul-Henning Kamp of the FreeBSD Project. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)vfs_cache.c 8.5 (Berkeley) 3/22/95 35 */ 36 37 #include <sys/cdefs.h> 38 __FBSDID("$FreeBSD$"); 39 40 #include "opt_ddb.h" 41 #include "opt_ktrace.h" 42 43 #include <sys/param.h> 44 #include <sys/systm.h> 45 #include <sys/capsicum.h> 46 #include <sys/counter.h> 47 #include <sys/filedesc.h> 48 #include <sys/fnv_hash.h> 49 #include <sys/kernel.h> 50 #include <sys/ktr.h> 51 #include <sys/lock.h> 52 #include <sys/malloc.h> 53 #include <sys/fcntl.h> 54 #include <sys/jail.h> 55 #include <sys/mount.h> 56 #include <sys/namei.h> 57 #include <sys/proc.h> 58 #include <sys/seqc.h> 59 #include <sys/sdt.h> 60 #include <sys/smr.h> 61 #include <sys/smp.h> 62 #include <sys/syscallsubr.h> 63 #include <sys/sysctl.h> 64 #include <sys/sysproto.h> 65 #include <sys/vnode.h> 66 #include <ck_queue.h> 67 #ifdef KTRACE 68 #include <sys/ktrace.h> 69 #endif 70 #ifdef INVARIANTS 71 #include <machine/_inttypes.h> 72 #endif 73 74 #include <sys/capsicum.h> 75 76 #include <security/audit/audit.h> 77 #include <security/mac/mac_framework.h> 78 79 #ifdef DDB 80 #include <ddb/ddb.h> 81 #endif 82 83 #include <vm/uma.h> 84 85 static SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 86 "Name cache"); 87 88 SDT_PROVIDER_DECLARE(vfs); 89 SDT_PROBE_DEFINE3(vfs, namecache, enter, done, "struct vnode *", "char *", 90 "struct vnode *"); 91 SDT_PROBE_DEFINE3(vfs, namecache, enter, duplicate, "struct vnode *", "char *", 92 "struct vnode *"); 93 SDT_PROBE_DEFINE2(vfs, namecache, enter_negative, done, "struct vnode *", 94 "char *"); 95 SDT_PROBE_DEFINE2(vfs, namecache, fullpath_smr, hit, "struct vnode *", 96 "const char *"); 97 SDT_PROBE_DEFINE4(vfs, namecache, fullpath_smr, miss, "struct vnode *", 98 "struct namecache *", "int", "int"); 99 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, entry, "struct vnode *"); 100 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, hit, "struct vnode *", 101 "char *", "struct vnode *"); 102 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, miss, "struct vnode *"); 103 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, return, "int", 104 "struct vnode *", "char *"); 105 SDT_PROBE_DEFINE3(vfs, namecache, lookup, hit, "struct vnode *", "char *", 106 "struct vnode *"); 107 SDT_PROBE_DEFINE2(vfs, namecache, lookup, hit__negative, 108 "struct vnode *", "char *"); 109 SDT_PROBE_DEFINE2(vfs, namecache, lookup, miss, "struct vnode *", 110 "char *"); 111 SDT_PROBE_DEFINE2(vfs, namecache, removecnp, hit, "struct vnode *", 112 "struct componentname *"); 113 SDT_PROBE_DEFINE2(vfs, namecache, removecnp, miss, "struct vnode *", 114 "struct componentname *"); 115 SDT_PROBE_DEFINE1(vfs, namecache, purge, done, "struct vnode *"); 116 SDT_PROBE_DEFINE1(vfs, namecache, purge, batch, "int"); 117 SDT_PROBE_DEFINE1(vfs, namecache, purge_negative, done, "struct vnode *"); 118 SDT_PROBE_DEFINE1(vfs, namecache, purgevfs, done, "struct mount *"); 119 SDT_PROBE_DEFINE3(vfs, namecache, zap, done, "struct vnode *", "char *", 120 "struct vnode *"); 121 SDT_PROBE_DEFINE2(vfs, namecache, zap_negative, done, "struct vnode *", 122 "char *"); 123 SDT_PROBE_DEFINE2(vfs, namecache, evict_negative, done, "struct vnode *", 124 "char *"); 125 126 SDT_PROBE_DEFINE3(vfs, fplookup, lookup, done, "struct nameidata", "int", "bool"); 127 SDT_PROBE_DECLARE(vfs, namei, lookup, entry); 128 SDT_PROBE_DECLARE(vfs, namei, lookup, return); 129 130 /* 131 * This structure describes the elements in the cache of recent 132 * names looked up by namei. 133 */ 134 struct negstate { 135 u_char neg_flag; 136 u_char neg_hit; 137 }; 138 _Static_assert(sizeof(struct negstate) <= sizeof(struct vnode *), 139 "the state must fit in a union with a pointer without growing it"); 140 141 struct namecache { 142 LIST_ENTRY(namecache) nc_src; /* source vnode list */ 143 TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */ 144 CK_SLIST_ENTRY(namecache) nc_hash;/* hash chain */ 145 struct vnode *nc_dvp; /* vnode of parent of name */ 146 union { 147 struct vnode *nu_vp; /* vnode the name refers to */ 148 struct negstate nu_neg;/* negative entry state */ 149 } n_un; 150 u_char nc_flag; /* flag bits */ 151 u_char nc_nlen; /* length of name */ 152 char nc_name[0]; /* segment name + nul */ 153 }; 154 155 /* 156 * struct namecache_ts repeats struct namecache layout up to the 157 * nc_nlen member. 158 * struct namecache_ts is used in place of struct namecache when time(s) need 159 * to be stored. The nc_dotdottime field is used when a cache entry is mapping 160 * both a non-dotdot directory name plus dotdot for the directory's 161 * parent. 162 * 163 * See below for alignment requirement. 164 */ 165 struct namecache_ts { 166 struct timespec nc_time; /* timespec provided by fs */ 167 struct timespec nc_dotdottime; /* dotdot timespec provided by fs */ 168 int nc_ticks; /* ticks value when entry was added */ 169 int nc_pad; 170 struct namecache nc_nc; 171 }; 172 173 TAILQ_HEAD(cache_freebatch, namecache); 174 175 /* 176 * At least mips n32 performs 64-bit accesses to timespec as found 177 * in namecache_ts and requires them to be aligned. Since others 178 * may be in the same spot suffer a little bit and enforce the 179 * alignment for everyone. Note this is a nop for 64-bit platforms. 180 */ 181 #define CACHE_ZONE_ALIGNMENT UMA_ALIGNOF(time_t) 182 183 /* 184 * TODO: the initial value of CACHE_PATH_CUTOFF was inherited from the 185 * 4.4 BSD codebase. Later on struct namecache was tweaked to become 186 * smaller and the value was bumped to retain the total size, but it 187 * was never re-evaluated for suitability. A simple test counting 188 * lengths during package building shows that the value of 45 covers 189 * about 86% of all added entries, reaching 99% at 65. 190 * 191 * Regardless of the above, use of dedicated zones instead of malloc may be 192 * inducing additional waste. This may be hard to address as said zones are 193 * tied to VFS SMR. Even if retaining them, the current split should be 194 * re-evaluated. 195 */ 196 #ifdef __LP64__ 197 #define CACHE_PATH_CUTOFF 45 198 #define CACHE_LARGE_PAD 6 199 #else 200 #define CACHE_PATH_CUTOFF 41 201 #define CACHE_LARGE_PAD 2 202 #endif 203 204 #define CACHE_ZONE_SMALL_SIZE (offsetof(struct namecache, nc_name) + CACHE_PATH_CUTOFF + 1) 205 #define CACHE_ZONE_SMALL_TS_SIZE (offsetof(struct namecache_ts, nc_nc) + CACHE_ZONE_SMALL_SIZE) 206 #define CACHE_ZONE_LARGE_SIZE (offsetof(struct namecache, nc_name) + NAME_MAX + 1 + CACHE_LARGE_PAD) 207 #define CACHE_ZONE_LARGE_TS_SIZE (offsetof(struct namecache_ts, nc_nc) + CACHE_ZONE_LARGE_SIZE) 208 209 _Static_assert((CACHE_ZONE_SMALL_SIZE % (CACHE_ZONE_ALIGNMENT + 1)) == 0, "bad zone size"); 210 _Static_assert((CACHE_ZONE_SMALL_TS_SIZE % (CACHE_ZONE_ALIGNMENT + 1)) == 0, "bad zone size"); 211 _Static_assert((CACHE_ZONE_LARGE_SIZE % (CACHE_ZONE_ALIGNMENT + 1)) == 0, "bad zone size"); 212 _Static_assert((CACHE_ZONE_LARGE_TS_SIZE % (CACHE_ZONE_ALIGNMENT + 1)) == 0, "bad zone size"); 213 214 #define nc_vp n_un.nu_vp 215 #define nc_neg n_un.nu_neg 216 217 /* 218 * Flags in namecache.nc_flag 219 */ 220 #define NCF_WHITE 0x01 221 #define NCF_ISDOTDOT 0x02 222 #define NCF_TS 0x04 223 #define NCF_DTS 0x08 224 #define NCF_DVDROP 0x10 225 #define NCF_NEGATIVE 0x20 226 #define NCF_INVALID 0x40 227 #define NCF_WIP 0x80 228 229 /* 230 * Flags in negstate.neg_flag 231 */ 232 #define NEG_HOT 0x01 233 234 static bool cache_neg_evict_cond(u_long lnumcache); 235 236 /* 237 * Mark an entry as invalid. 238 * 239 * This is called before it starts getting deconstructed. 240 */ 241 static void 242 cache_ncp_invalidate(struct namecache *ncp) 243 { 244 245 KASSERT((ncp->nc_flag & NCF_INVALID) == 0, 246 ("%s: entry %p already invalid", __func__, ncp)); 247 atomic_store_char(&ncp->nc_flag, ncp->nc_flag | NCF_INVALID); 248 atomic_thread_fence_rel(); 249 } 250 251 /* 252 * Check whether the entry can be safely used. 253 * 254 * All places which elide locks are supposed to call this after they are 255 * done with reading from an entry. 256 */ 257 #define cache_ncp_canuse(ncp) ({ \ 258 struct namecache *_ncp = (ncp); \ 259 u_char _nc_flag; \ 260 \ 261 atomic_thread_fence_acq(); \ 262 _nc_flag = atomic_load_char(&_ncp->nc_flag); \ 263 __predict_true((_nc_flag & (NCF_INVALID | NCF_WIP)) == 0); \ 264 }) 265 266 /* 267 * Like the above but also checks NCF_WHITE. 268 */ 269 #define cache_fpl_neg_ncp_canuse(ncp) ({ \ 270 struct namecache *_ncp = (ncp); \ 271 u_char _nc_flag; \ 272 \ 273 atomic_thread_fence_acq(); \ 274 _nc_flag = atomic_load_char(&_ncp->nc_flag); \ 275 __predict_true((_nc_flag & (NCF_INVALID | NCF_WIP | NCF_WHITE)) == 0); \ 276 }) 277 278 /* 279 * Name caching works as follows: 280 * 281 * Names found by directory scans are retained in a cache 282 * for future reference. It is managed LRU, so frequently 283 * used names will hang around. Cache is indexed by hash value 284 * obtained from (dvp, name) where dvp refers to the directory 285 * containing name. 286 * 287 * If it is a "negative" entry, (i.e. for a name that is known NOT to 288 * exist) the vnode pointer will be NULL. 289 * 290 * Upon reaching the last segment of a path, if the reference 291 * is for DELETE, or NOCACHE is set (rewrite), and the 292 * name is located in the cache, it will be dropped. 293 * 294 * These locks are used (in the order in which they can be taken): 295 * NAME TYPE ROLE 296 * vnodelock mtx vnode lists and v_cache_dd field protection 297 * bucketlock mtx for access to given set of hash buckets 298 * neglist mtx negative entry LRU management 299 * 300 * It is legal to take multiple vnodelock and bucketlock locks. The locking 301 * order is lower address first. Both are recursive. 302 * 303 * "." lookups are lockless. 304 * 305 * ".." and vnode -> name lookups require vnodelock. 306 * 307 * name -> vnode lookup requires the relevant bucketlock to be held for reading. 308 * 309 * Insertions and removals of entries require involved vnodes and bucketlocks 310 * to be locked to provide safe operation against other threads modifying the 311 * cache. 312 * 313 * Some lookups result in removal of the found entry (e.g. getting rid of a 314 * negative entry with the intent to create a positive one), which poses a 315 * problem when multiple threads reach the state. Similarly, two different 316 * threads can purge two different vnodes and try to remove the same name. 317 * 318 * If the already held vnode lock is lower than the second required lock, we 319 * can just take the other lock. However, in the opposite case, this could 320 * deadlock. As such, this is resolved by trylocking and if that fails unlocking 321 * the first node, locking everything in order and revalidating the state. 322 */ 323 324 VFS_SMR_DECLARE; 325 326 static SYSCTL_NODE(_vfs_cache, OID_AUTO, param, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 327 "Name cache parameters"); 328 329 static u_int __read_mostly ncsize; /* the size as computed on creation or resizing */ 330 SYSCTL_UINT(_vfs_cache_param, OID_AUTO, size, CTLFLAG_RW, &ncsize, 0, 331 "Total namecache capacity"); 332 333 u_int ncsizefactor = 2; 334 SYSCTL_UINT(_vfs_cache_param, OID_AUTO, sizefactor, CTLFLAG_RW, &ncsizefactor, 0, 335 "Size factor for namecache"); 336 337 static u_long __read_mostly ncnegfactor = 5; /* ratio of negative entries */ 338 SYSCTL_ULONG(_vfs_cache_param, OID_AUTO, negfactor, CTLFLAG_RW, &ncnegfactor, 0, 339 "Ratio of negative namecache entries"); 340 341 /* 342 * Negative entry % of namecache capacity above which automatic eviction is allowed. 343 * 344 * Check cache_neg_evict_cond for details. 345 */ 346 static u_int ncnegminpct = 3; 347 348 static u_int __read_mostly neg_min; /* the above recomputed against ncsize */ 349 SYSCTL_UINT(_vfs_cache_param, OID_AUTO, negmin, CTLFLAG_RD, &neg_min, 0, 350 "Negative entry count above which automatic eviction is allowed"); 351 352 /* 353 * Structures associated with name caching. 354 */ 355 #define NCHHASH(hash) \ 356 (&nchashtbl[(hash) & nchash]) 357 static __read_mostly CK_SLIST_HEAD(nchashhead, namecache) *nchashtbl;/* Hash Table */ 358 static u_long __read_mostly nchash; /* size of hash table */ 359 SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, 360 "Size of namecache hash table"); 361 static u_long __exclusive_cache_line numneg; /* number of negative entries allocated */ 362 static u_long __exclusive_cache_line numcache;/* number of cache entries allocated */ 363 364 struct nchstats nchstats; /* cache effectiveness statistics */ 365 366 static bool __read_frequently cache_fast_revlookup = true; 367 SYSCTL_BOOL(_vfs, OID_AUTO, cache_fast_revlookup, CTLFLAG_RW, 368 &cache_fast_revlookup, 0, ""); 369 370 static u_int __exclusive_cache_line neg_cycle; 371 372 #define ncneghash 3 373 #define numneglists (ncneghash + 1) 374 375 struct neglist { 376 struct mtx nl_evict_lock; 377 struct mtx nl_lock __aligned(CACHE_LINE_SIZE); 378 TAILQ_HEAD(, namecache) nl_list; 379 TAILQ_HEAD(, namecache) nl_hotlist; 380 u_long nl_hotnum; 381 } __aligned(CACHE_LINE_SIZE); 382 383 static struct neglist neglists[numneglists]; 384 385 static inline struct neglist * 386 NCP2NEGLIST(struct namecache *ncp) 387 { 388 389 return (&neglists[(((uintptr_t)(ncp) >> 8) & ncneghash)]); 390 } 391 392 static inline struct negstate * 393 NCP2NEGSTATE(struct namecache *ncp) 394 { 395 396 MPASS(ncp->nc_flag & NCF_NEGATIVE); 397 return (&ncp->nc_neg); 398 } 399 400 #define numbucketlocks (ncbuckethash + 1) 401 static u_int __read_mostly ncbuckethash; 402 static struct mtx_padalign __read_mostly *bucketlocks; 403 #define HASH2BUCKETLOCK(hash) \ 404 ((struct mtx *)(&bucketlocks[((hash) & ncbuckethash)])) 405 406 #define numvnodelocks (ncvnodehash + 1) 407 static u_int __read_mostly ncvnodehash; 408 static struct mtx __read_mostly *vnodelocks; 409 static inline struct mtx * 410 VP2VNODELOCK(struct vnode *vp) 411 { 412 413 return (&vnodelocks[(((uintptr_t)(vp) >> 8) & ncvnodehash)]); 414 } 415 416 static void 417 cache_out_ts(struct namecache *ncp, struct timespec *tsp, int *ticksp) 418 { 419 struct namecache_ts *ncp_ts; 420 421 KASSERT((ncp->nc_flag & NCF_TS) != 0 || 422 (tsp == NULL && ticksp == NULL), 423 ("No NCF_TS")); 424 425 if (tsp == NULL) 426 return; 427 428 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); 429 *tsp = ncp_ts->nc_time; 430 *ticksp = ncp_ts->nc_ticks; 431 } 432 433 #ifdef DEBUG_CACHE 434 static int __read_mostly doingcache = 1; /* 1 => enable the cache */ 435 SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0, 436 "VFS namecache enabled"); 437 #endif 438 439 /* Export size information to userland */ 440 SYSCTL_INT(_debug_sizeof, OID_AUTO, namecache, CTLFLAG_RD, SYSCTL_NULL_INT_PTR, 441 sizeof(struct namecache), "sizeof(struct namecache)"); 442 443 /* 444 * The new name cache statistics 445 */ 446 static SYSCTL_NODE(_vfs_cache, OID_AUTO, stats, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 447 "Name cache statistics"); 448 449 #define STATNODE_ULONG(name, varname, descr) \ 450 SYSCTL_ULONG(_vfs_cache_stats, OID_AUTO, name, CTLFLAG_RD, &varname, 0, descr); 451 #define STATNODE_COUNTER(name, varname, descr) \ 452 static COUNTER_U64_DEFINE_EARLY(varname); \ 453 SYSCTL_COUNTER_U64(_vfs_cache_stats, OID_AUTO, name, CTLFLAG_RD, &varname, \ 454 descr); 455 STATNODE_ULONG(neg, numneg, "Number of negative cache entries"); 456 STATNODE_ULONG(count, numcache, "Number of cache entries"); 457 STATNODE_COUNTER(heldvnodes, numcachehv, "Number of namecache entries with vnodes held"); 458 STATNODE_COUNTER(drops, numdrops, "Number of dropped entries due to reaching the limit"); 459 STATNODE_COUNTER(dothits, dothits, "Number of '.' hits"); 460 STATNODE_COUNTER(dotdothis, dotdothits, "Number of '..' hits"); 461 STATNODE_COUNTER(miss, nummiss, "Number of cache misses"); 462 STATNODE_COUNTER(misszap, nummisszap, "Number of cache misses we do not want to cache"); 463 STATNODE_COUNTER(posszaps, numposzaps, 464 "Number of cache hits (positive) we do not want to cache"); 465 STATNODE_COUNTER(poshits, numposhits, "Number of cache hits (positive)"); 466 STATNODE_COUNTER(negzaps, numnegzaps, 467 "Number of cache hits (negative) we do not want to cache"); 468 STATNODE_COUNTER(neghits, numneghits, "Number of cache hits (negative)"); 469 /* These count for vn_getcwd(), too. */ 470 STATNODE_COUNTER(fullpathcalls, numfullpathcalls, "Number of fullpath search calls"); 471 STATNODE_COUNTER(fullpathfail1, numfullpathfail1, "Number of fullpath search errors (ENOTDIR)"); 472 STATNODE_COUNTER(fullpathfail2, numfullpathfail2, 473 "Number of fullpath search errors (VOP_VPTOCNP failures)"); 474 STATNODE_COUNTER(fullpathfail4, numfullpathfail4, "Number of fullpath search errors (ENOMEM)"); 475 STATNODE_COUNTER(fullpathfound, numfullpathfound, "Number of successful fullpath calls"); 476 477 /* 478 * Debug or developer statistics. 479 */ 480 static SYSCTL_NODE(_vfs_cache, OID_AUTO, debug, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 481 "Name cache debugging"); 482 #define DEBUGNODE_ULONG(name, varname, descr) \ 483 SYSCTL_ULONG(_vfs_cache_debug, OID_AUTO, name, CTLFLAG_RD, &varname, 0, descr); 484 #define DEBUGNODE_COUNTER(name, varname, descr) \ 485 static COUNTER_U64_DEFINE_EARLY(varname); \ 486 SYSCTL_COUNTER_U64(_vfs_cache_debug, OID_AUTO, name, CTLFLAG_RD, &varname, \ 487 descr); 488 DEBUGNODE_COUNTER(zap_bucket_relock_success, zap_bucket_relock_success, 489 "Number of successful removals after relocking"); 490 static long zap_bucket_fail; 491 DEBUGNODE_ULONG(zap_bucket_fail, zap_bucket_fail, ""); 492 static long zap_bucket_fail2; 493 DEBUGNODE_ULONG(zap_bucket_fail2, zap_bucket_fail2, ""); 494 static long cache_lock_vnodes_cel_3_failures; 495 DEBUGNODE_ULONG(vnodes_cel_3_failures, cache_lock_vnodes_cel_3_failures, 496 "Number of times 3-way vnode locking failed"); 497 498 static void cache_zap_locked(struct namecache *ncp); 499 static int vn_fullpath_hardlink(struct nameidata *ndp, char **retbuf, 500 char **freebuf, size_t *buflen); 501 static int vn_fullpath_any_smr(struct vnode *vp, struct vnode *rdir, char *buf, 502 char **retbuf, size_t *buflen, size_t addend); 503 static int vn_fullpath_any(struct vnode *vp, struct vnode *rdir, char *buf, 504 char **retbuf, size_t *buflen); 505 static int vn_fullpath_dir(struct vnode *vp, struct vnode *rdir, char *buf, 506 char **retbuf, size_t *len, size_t addend); 507 508 static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); 509 510 static inline void 511 cache_assert_vlp_locked(struct mtx *vlp) 512 { 513 514 if (vlp != NULL) 515 mtx_assert(vlp, MA_OWNED); 516 } 517 518 static inline void 519 cache_assert_vnode_locked(struct vnode *vp) 520 { 521 struct mtx *vlp; 522 523 vlp = VP2VNODELOCK(vp); 524 cache_assert_vlp_locked(vlp); 525 } 526 527 /* 528 * Directory vnodes with entries are held for two reasons: 529 * 1. make them less of a target for reclamation in vnlru 530 * 2. suffer smaller performance penalty in locked lookup as requeieing is avoided 531 * 532 * It will be feasible to stop doing it altogether if all filesystems start 533 * supporting lockless lookup. 534 */ 535 static void 536 cache_hold_vnode(struct vnode *vp) 537 { 538 539 cache_assert_vnode_locked(vp); 540 VNPASS(LIST_EMPTY(&vp->v_cache_src), vp); 541 vhold(vp); 542 counter_u64_add(numcachehv, 1); 543 } 544 545 static void 546 cache_drop_vnode(struct vnode *vp) 547 { 548 549 /* 550 * Called after all locks are dropped, meaning we can't assert 551 * on the state of v_cache_src. 552 */ 553 vdrop(vp); 554 counter_u64_add(numcachehv, -1); 555 } 556 557 /* 558 * UMA zones. 559 */ 560 static uma_zone_t __read_mostly cache_zone_small; 561 static uma_zone_t __read_mostly cache_zone_small_ts; 562 static uma_zone_t __read_mostly cache_zone_large; 563 static uma_zone_t __read_mostly cache_zone_large_ts; 564 565 static struct namecache * 566 cache_alloc_uma(int len, bool ts) 567 { 568 struct namecache_ts *ncp_ts; 569 struct namecache *ncp; 570 571 if (__predict_false(ts)) { 572 if (len <= CACHE_PATH_CUTOFF) 573 ncp_ts = uma_zalloc_smr(cache_zone_small_ts, M_WAITOK); 574 else 575 ncp_ts = uma_zalloc_smr(cache_zone_large_ts, M_WAITOK); 576 ncp = &ncp_ts->nc_nc; 577 } else { 578 if (len <= CACHE_PATH_CUTOFF) 579 ncp = uma_zalloc_smr(cache_zone_small, M_WAITOK); 580 else 581 ncp = uma_zalloc_smr(cache_zone_large, M_WAITOK); 582 } 583 return (ncp); 584 } 585 586 static void 587 cache_free_uma(struct namecache *ncp) 588 { 589 struct namecache_ts *ncp_ts; 590 591 if (__predict_false(ncp->nc_flag & NCF_TS)) { 592 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); 593 if (ncp->nc_nlen <= CACHE_PATH_CUTOFF) 594 uma_zfree_smr(cache_zone_small_ts, ncp_ts); 595 else 596 uma_zfree_smr(cache_zone_large_ts, ncp_ts); 597 } else { 598 if (ncp->nc_nlen <= CACHE_PATH_CUTOFF) 599 uma_zfree_smr(cache_zone_small, ncp); 600 else 601 uma_zfree_smr(cache_zone_large, ncp); 602 } 603 } 604 605 static struct namecache * 606 cache_alloc(int len, bool ts) 607 { 608 u_long lnumcache; 609 610 /* 611 * Avoid blowout in namecache entries. 612 * 613 * Bugs: 614 * 1. filesystems may end up trying to add an already existing entry 615 * (for example this can happen after a cache miss during concurrent 616 * lookup), in which case we will call cache_neg_evict despite not 617 * adding anything. 618 * 2. the routine may fail to free anything and no provisions are made 619 * to make it try harder (see the inside for failure modes) 620 * 3. it only ever looks at negative entries. 621 */ 622 lnumcache = atomic_fetchadd_long(&numcache, 1) + 1; 623 if (cache_neg_evict_cond(lnumcache)) { 624 lnumcache = atomic_load_long(&numcache); 625 } 626 if (__predict_false(lnumcache >= ncsize)) { 627 atomic_subtract_long(&numcache, 1); 628 counter_u64_add(numdrops, 1); 629 return (NULL); 630 } 631 return (cache_alloc_uma(len, ts)); 632 } 633 634 static void 635 cache_free(struct namecache *ncp) 636 { 637 638 MPASS(ncp != NULL); 639 if ((ncp->nc_flag & NCF_DVDROP) != 0) { 640 cache_drop_vnode(ncp->nc_dvp); 641 } 642 cache_free_uma(ncp); 643 atomic_subtract_long(&numcache, 1); 644 } 645 646 static void 647 cache_free_batch(struct cache_freebatch *batch) 648 { 649 struct namecache *ncp, *nnp; 650 int i; 651 652 i = 0; 653 if (TAILQ_EMPTY(batch)) 654 goto out; 655 TAILQ_FOREACH_SAFE(ncp, batch, nc_dst, nnp) { 656 if ((ncp->nc_flag & NCF_DVDROP) != 0) { 657 cache_drop_vnode(ncp->nc_dvp); 658 } 659 cache_free_uma(ncp); 660 i++; 661 } 662 atomic_subtract_long(&numcache, i); 663 out: 664 SDT_PROBE1(vfs, namecache, purge, batch, i); 665 } 666 667 /* 668 * TODO: With the value stored we can do better than computing the hash based 669 * on the address. The choice of FNV should also be revisited. 670 */ 671 static void 672 cache_prehash(struct vnode *vp) 673 { 674 675 vp->v_nchash = fnv_32_buf(&vp, sizeof(vp), FNV1_32_INIT); 676 } 677 678 static uint32_t 679 cache_get_hash(char *name, u_char len, struct vnode *dvp) 680 { 681 682 return (fnv_32_buf(name, len, dvp->v_nchash)); 683 } 684 685 static inline struct nchashhead * 686 NCP2BUCKET(struct namecache *ncp) 687 { 688 uint32_t hash; 689 690 hash = cache_get_hash(ncp->nc_name, ncp->nc_nlen, ncp->nc_dvp); 691 return (NCHHASH(hash)); 692 } 693 694 static inline struct mtx * 695 NCP2BUCKETLOCK(struct namecache *ncp) 696 { 697 uint32_t hash; 698 699 hash = cache_get_hash(ncp->nc_name, ncp->nc_nlen, ncp->nc_dvp); 700 return (HASH2BUCKETLOCK(hash)); 701 } 702 703 #ifdef INVARIANTS 704 static void 705 cache_assert_bucket_locked(struct namecache *ncp) 706 { 707 struct mtx *blp; 708 709 blp = NCP2BUCKETLOCK(ncp); 710 mtx_assert(blp, MA_OWNED); 711 } 712 713 static void 714 cache_assert_bucket_unlocked(struct namecache *ncp) 715 { 716 struct mtx *blp; 717 718 blp = NCP2BUCKETLOCK(ncp); 719 mtx_assert(blp, MA_NOTOWNED); 720 } 721 #else 722 #define cache_assert_bucket_locked(x) do { } while (0) 723 #define cache_assert_bucket_unlocked(x) do { } while (0) 724 #endif 725 726 #define cache_sort_vnodes(x, y) _cache_sort_vnodes((void **)(x), (void **)(y)) 727 static void 728 _cache_sort_vnodes(void **p1, void **p2) 729 { 730 void *tmp; 731 732 MPASS(*p1 != NULL || *p2 != NULL); 733 734 if (*p1 > *p2) { 735 tmp = *p2; 736 *p2 = *p1; 737 *p1 = tmp; 738 } 739 } 740 741 static void 742 cache_lock_all_buckets(void) 743 { 744 u_int i; 745 746 for (i = 0; i < numbucketlocks; i++) 747 mtx_lock(&bucketlocks[i]); 748 } 749 750 static void 751 cache_unlock_all_buckets(void) 752 { 753 u_int i; 754 755 for (i = 0; i < numbucketlocks; i++) 756 mtx_unlock(&bucketlocks[i]); 757 } 758 759 static void 760 cache_lock_all_vnodes(void) 761 { 762 u_int i; 763 764 for (i = 0; i < numvnodelocks; i++) 765 mtx_lock(&vnodelocks[i]); 766 } 767 768 static void 769 cache_unlock_all_vnodes(void) 770 { 771 u_int i; 772 773 for (i = 0; i < numvnodelocks; i++) 774 mtx_unlock(&vnodelocks[i]); 775 } 776 777 static int 778 cache_trylock_vnodes(struct mtx *vlp1, struct mtx *vlp2) 779 { 780 781 cache_sort_vnodes(&vlp1, &vlp2); 782 783 if (vlp1 != NULL) { 784 if (!mtx_trylock(vlp1)) 785 return (EAGAIN); 786 } 787 if (!mtx_trylock(vlp2)) { 788 if (vlp1 != NULL) 789 mtx_unlock(vlp1); 790 return (EAGAIN); 791 } 792 793 return (0); 794 } 795 796 static void 797 cache_lock_vnodes(struct mtx *vlp1, struct mtx *vlp2) 798 { 799 800 MPASS(vlp1 != NULL || vlp2 != NULL); 801 MPASS(vlp1 <= vlp2); 802 803 if (vlp1 != NULL) 804 mtx_lock(vlp1); 805 if (vlp2 != NULL) 806 mtx_lock(vlp2); 807 } 808 809 static void 810 cache_unlock_vnodes(struct mtx *vlp1, struct mtx *vlp2) 811 { 812 813 MPASS(vlp1 != NULL || vlp2 != NULL); 814 815 if (vlp1 != NULL) 816 mtx_unlock(vlp1); 817 if (vlp2 != NULL) 818 mtx_unlock(vlp2); 819 } 820 821 static int 822 sysctl_nchstats(SYSCTL_HANDLER_ARGS) 823 { 824 struct nchstats snap; 825 826 if (req->oldptr == NULL) 827 return (SYSCTL_OUT(req, 0, sizeof(snap))); 828 829 snap = nchstats; 830 snap.ncs_goodhits = counter_u64_fetch(numposhits); 831 snap.ncs_neghits = counter_u64_fetch(numneghits); 832 snap.ncs_badhits = counter_u64_fetch(numposzaps) + 833 counter_u64_fetch(numnegzaps); 834 snap.ncs_miss = counter_u64_fetch(nummisszap) + 835 counter_u64_fetch(nummiss); 836 837 return (SYSCTL_OUT(req, &snap, sizeof(snap))); 838 } 839 SYSCTL_PROC(_vfs_cache, OID_AUTO, nchstats, CTLTYPE_OPAQUE | CTLFLAG_RD | 840 CTLFLAG_MPSAFE, 0, 0, sysctl_nchstats, "LU", 841 "VFS cache effectiveness statistics"); 842 843 static void 844 cache_recalc_neg_min(u_int val) 845 { 846 847 neg_min = (ncsize * val) / 100; 848 } 849 850 static int 851 sysctl_negminpct(SYSCTL_HANDLER_ARGS) 852 { 853 u_int val; 854 int error; 855 856 val = ncnegminpct; 857 error = sysctl_handle_int(oidp, &val, 0, req); 858 if (error != 0 || req->newptr == NULL) 859 return (error); 860 861 if (val == ncnegminpct) 862 return (0); 863 if (val < 0 || val > 99) 864 return (EINVAL); 865 ncnegminpct = val; 866 cache_recalc_neg_min(val); 867 return (0); 868 } 869 870 SYSCTL_PROC(_vfs_cache_param, OID_AUTO, negminpct, 871 CTLTYPE_INT | CTLFLAG_MPSAFE | CTLFLAG_RW, NULL, 0, sysctl_negminpct, 872 "I", "Negative entry \% of namecache capacity above which automatic eviction is allowed"); 873 874 #ifdef DIAGNOSTIC 875 /* 876 * Grab an atomic snapshot of the name cache hash chain lengths 877 */ 878 static SYSCTL_NODE(_debug, OID_AUTO, hashstat, 879 CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 880 "hash table stats"); 881 882 static int 883 sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS) 884 { 885 struct nchashhead *ncpp; 886 struct namecache *ncp; 887 int i, error, n_nchash, *cntbuf; 888 889 retry: 890 n_nchash = nchash + 1; /* nchash is max index, not count */ 891 if (req->oldptr == NULL) 892 return SYSCTL_OUT(req, 0, n_nchash * sizeof(int)); 893 cntbuf = malloc(n_nchash * sizeof(int), M_TEMP, M_ZERO | M_WAITOK); 894 cache_lock_all_buckets(); 895 if (n_nchash != nchash + 1) { 896 cache_unlock_all_buckets(); 897 free(cntbuf, M_TEMP); 898 goto retry; 899 } 900 /* Scan hash tables counting entries */ 901 for (ncpp = nchashtbl, i = 0; i < n_nchash; ncpp++, i++) 902 CK_SLIST_FOREACH(ncp, ncpp, nc_hash) 903 cntbuf[i]++; 904 cache_unlock_all_buckets(); 905 for (error = 0, i = 0; i < n_nchash; i++) 906 if ((error = SYSCTL_OUT(req, &cntbuf[i], sizeof(int))) != 0) 907 break; 908 free(cntbuf, M_TEMP); 909 return (error); 910 } 911 SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD| 912 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_rawnchash, "S,int", 913 "nchash chain lengths"); 914 915 static int 916 sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS) 917 { 918 int error; 919 struct nchashhead *ncpp; 920 struct namecache *ncp; 921 int n_nchash; 922 int count, maxlength, used, pct; 923 924 if (!req->oldptr) 925 return SYSCTL_OUT(req, 0, 4 * sizeof(int)); 926 927 cache_lock_all_buckets(); 928 n_nchash = nchash + 1; /* nchash is max index, not count */ 929 used = 0; 930 maxlength = 0; 931 932 /* Scan hash tables for applicable entries */ 933 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { 934 count = 0; 935 CK_SLIST_FOREACH(ncp, ncpp, nc_hash) { 936 count++; 937 } 938 if (count) 939 used++; 940 if (maxlength < count) 941 maxlength = count; 942 } 943 n_nchash = nchash + 1; 944 cache_unlock_all_buckets(); 945 pct = (used * 100) / (n_nchash / 100); 946 error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash)); 947 if (error) 948 return (error); 949 error = SYSCTL_OUT(req, &used, sizeof(used)); 950 if (error) 951 return (error); 952 error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength)); 953 if (error) 954 return (error); 955 error = SYSCTL_OUT(req, &pct, sizeof(pct)); 956 if (error) 957 return (error); 958 return (0); 959 } 960 SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD| 961 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_nchash, "I", 962 "nchash statistics (number of total/used buckets, maximum chain length, usage percentage)"); 963 #endif 964 965 /* 966 * Negative entries management 967 * 968 * Various workloads create plenty of negative entries and barely use them 969 * afterwards. Moreover malicious users can keep performing bogus lookups 970 * adding even more entries. For example "make tinderbox" as of writing this 971 * comment ends up with 2.6M namecache entries in total, 1.2M of which are 972 * negative. 973 * 974 * As such, a rather aggressive eviction method is needed. The currently 975 * employed method is a placeholder. 976 * 977 * Entries are split over numneglists separate lists, each of which is further 978 * split into hot and cold entries. Entries get promoted after getting a hit. 979 * Eviction happens on addition of new entry. 980 */ 981 static SYSCTL_NODE(_vfs_cache, OID_AUTO, neg, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 982 "Name cache negative entry statistics"); 983 984 SYSCTL_ULONG(_vfs_cache_neg, OID_AUTO, count, CTLFLAG_RD, &numneg, 0, 985 "Number of negative cache entries"); 986 987 static COUNTER_U64_DEFINE_EARLY(neg_created); 988 SYSCTL_COUNTER_U64(_vfs_cache_neg, OID_AUTO, created, CTLFLAG_RD, &neg_created, 989 "Number of created negative entries"); 990 991 static COUNTER_U64_DEFINE_EARLY(neg_evicted); 992 SYSCTL_COUNTER_U64(_vfs_cache_neg, OID_AUTO, evicted, CTLFLAG_RD, &neg_evicted, 993 "Number of evicted negative entries"); 994 995 static COUNTER_U64_DEFINE_EARLY(neg_evict_skipped_empty); 996 SYSCTL_COUNTER_U64(_vfs_cache_neg, OID_AUTO, evict_skipped_empty, CTLFLAG_RD, 997 &neg_evict_skipped_empty, 998 "Number of times evicting failed due to lack of entries"); 999 1000 static COUNTER_U64_DEFINE_EARLY(neg_evict_skipped_missed); 1001 SYSCTL_COUNTER_U64(_vfs_cache_neg, OID_AUTO, evict_skipped_missed, CTLFLAG_RD, 1002 &neg_evict_skipped_missed, 1003 "Number of times evicting failed due to target entry disappearing"); 1004 1005 static COUNTER_U64_DEFINE_EARLY(neg_evict_skipped_contended); 1006 SYSCTL_COUNTER_U64(_vfs_cache_neg, OID_AUTO, evict_skipped_contended, CTLFLAG_RD, 1007 &neg_evict_skipped_contended, 1008 "Number of times evicting failed due to contention"); 1009 1010 SYSCTL_COUNTER_U64(_vfs_cache_neg, OID_AUTO, hits, CTLFLAG_RD, &numneghits, 1011 "Number of cache hits (negative)"); 1012 1013 static int 1014 sysctl_neg_hot(SYSCTL_HANDLER_ARGS) 1015 { 1016 int i, out; 1017 1018 out = 0; 1019 for (i = 0; i < numneglists; i++) 1020 out += neglists[i].nl_hotnum; 1021 1022 return (SYSCTL_OUT(req, &out, sizeof(out))); 1023 } 1024 SYSCTL_PROC(_vfs_cache_neg, OID_AUTO, hot, CTLTYPE_INT | CTLFLAG_RD | 1025 CTLFLAG_MPSAFE, 0, 0, sysctl_neg_hot, "I", 1026 "Number of hot negative entries"); 1027 1028 static void 1029 cache_neg_init(struct namecache *ncp) 1030 { 1031 struct negstate *ns; 1032 1033 ncp->nc_flag |= NCF_NEGATIVE; 1034 ns = NCP2NEGSTATE(ncp); 1035 ns->neg_flag = 0; 1036 ns->neg_hit = 0; 1037 counter_u64_add(neg_created, 1); 1038 } 1039 1040 #define CACHE_NEG_PROMOTION_THRESH 2 1041 1042 static bool 1043 cache_neg_hit_prep(struct namecache *ncp) 1044 { 1045 struct negstate *ns; 1046 u_char n; 1047 1048 ns = NCP2NEGSTATE(ncp); 1049 n = atomic_load_char(&ns->neg_hit); 1050 for (;;) { 1051 if (n >= CACHE_NEG_PROMOTION_THRESH) 1052 return (false); 1053 if (atomic_fcmpset_8(&ns->neg_hit, &n, n + 1)) 1054 break; 1055 } 1056 return (n + 1 == CACHE_NEG_PROMOTION_THRESH); 1057 } 1058 1059 /* 1060 * Nothing to do here but it is provided for completeness as some 1061 * cache_neg_hit_prep callers may end up returning without even 1062 * trying to promote. 1063 */ 1064 #define cache_neg_hit_abort(ncp) do { } while (0) 1065 1066 static void 1067 cache_neg_hit_finish(struct namecache *ncp) 1068 { 1069 1070 SDT_PROBE2(vfs, namecache, lookup, hit__negative, ncp->nc_dvp, ncp->nc_name); 1071 counter_u64_add(numneghits, 1); 1072 } 1073 1074 /* 1075 * Move a negative entry to the hot list. 1076 */ 1077 static void 1078 cache_neg_promote_locked(struct namecache *ncp) 1079 { 1080 struct neglist *nl; 1081 struct negstate *ns; 1082 1083 ns = NCP2NEGSTATE(ncp); 1084 nl = NCP2NEGLIST(ncp); 1085 mtx_assert(&nl->nl_lock, MA_OWNED); 1086 if ((ns->neg_flag & NEG_HOT) == 0) { 1087 TAILQ_REMOVE(&nl->nl_list, ncp, nc_dst); 1088 TAILQ_INSERT_TAIL(&nl->nl_hotlist, ncp, nc_dst); 1089 nl->nl_hotnum++; 1090 ns->neg_flag |= NEG_HOT; 1091 } 1092 } 1093 1094 /* 1095 * Move a hot negative entry to the cold list. 1096 */ 1097 static void 1098 cache_neg_demote_locked(struct namecache *ncp) 1099 { 1100 struct neglist *nl; 1101 struct negstate *ns; 1102 1103 ns = NCP2NEGSTATE(ncp); 1104 nl = NCP2NEGLIST(ncp); 1105 mtx_assert(&nl->nl_lock, MA_OWNED); 1106 MPASS(ns->neg_flag & NEG_HOT); 1107 TAILQ_REMOVE(&nl->nl_hotlist, ncp, nc_dst); 1108 TAILQ_INSERT_TAIL(&nl->nl_list, ncp, nc_dst); 1109 nl->nl_hotnum--; 1110 ns->neg_flag &= ~NEG_HOT; 1111 atomic_store_char(&ns->neg_hit, 0); 1112 } 1113 1114 /* 1115 * Move a negative entry to the hot list if it matches the lookup. 1116 * 1117 * We have to take locks, but they may be contended and in the worst 1118 * case we may need to go off CPU. We don't want to spin within the 1119 * smr section and we can't block with it. Exiting the section means 1120 * the found entry could have been evicted. We are going to look it 1121 * up again. 1122 */ 1123 static bool 1124 cache_neg_promote_cond(struct vnode *dvp, struct componentname *cnp, 1125 struct namecache *oncp, uint32_t hash) 1126 { 1127 struct namecache *ncp; 1128 struct neglist *nl; 1129 u_char nc_flag; 1130 1131 nl = NCP2NEGLIST(oncp); 1132 1133 mtx_lock(&nl->nl_lock); 1134 /* 1135 * For hash iteration. 1136 */ 1137 vfs_smr_enter(); 1138 1139 /* 1140 * Avoid all surprises by only succeeding if we got the same entry and 1141 * bailing completely otherwise. 1142 * XXX There are no provisions to keep the vnode around, meaning we may 1143 * end up promoting a negative entry for a *new* vnode and returning 1144 * ENOENT on its account. This is the error we want to return anyway 1145 * and promotion is harmless. 1146 * 1147 * In particular at this point there can be a new ncp which matches the 1148 * search but hashes to a different neglist. 1149 */ 1150 CK_SLIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 1151 if (ncp == oncp) 1152 break; 1153 } 1154 1155 /* 1156 * No match to begin with. 1157 */ 1158 if (__predict_false(ncp == NULL)) { 1159 goto out_abort; 1160 } 1161 1162 /* 1163 * The newly found entry may be something different... 1164 */ 1165 if (!(ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 1166 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen))) { 1167 goto out_abort; 1168 } 1169 1170 /* 1171 * ... and not even negative. 1172 */ 1173 nc_flag = atomic_load_char(&ncp->nc_flag); 1174 if ((nc_flag & NCF_NEGATIVE) == 0) { 1175 goto out_abort; 1176 } 1177 1178 if (!cache_ncp_canuse(ncp)) { 1179 goto out_abort; 1180 } 1181 1182 cache_neg_promote_locked(ncp); 1183 cache_neg_hit_finish(ncp); 1184 vfs_smr_exit(); 1185 mtx_unlock(&nl->nl_lock); 1186 return (true); 1187 out_abort: 1188 vfs_smr_exit(); 1189 mtx_unlock(&nl->nl_lock); 1190 return (false); 1191 } 1192 1193 static void 1194 cache_neg_promote(struct namecache *ncp) 1195 { 1196 struct neglist *nl; 1197 1198 nl = NCP2NEGLIST(ncp); 1199 mtx_lock(&nl->nl_lock); 1200 cache_neg_promote_locked(ncp); 1201 mtx_unlock(&nl->nl_lock); 1202 } 1203 1204 static void 1205 cache_neg_insert(struct namecache *ncp) 1206 { 1207 struct neglist *nl; 1208 1209 MPASS(ncp->nc_flag & NCF_NEGATIVE); 1210 cache_assert_bucket_locked(ncp); 1211 nl = NCP2NEGLIST(ncp); 1212 mtx_lock(&nl->nl_lock); 1213 TAILQ_INSERT_TAIL(&nl->nl_list, ncp, nc_dst); 1214 mtx_unlock(&nl->nl_lock); 1215 atomic_add_long(&numneg, 1); 1216 } 1217 1218 static void 1219 cache_neg_remove(struct namecache *ncp) 1220 { 1221 struct neglist *nl; 1222 struct negstate *ns; 1223 1224 cache_assert_bucket_locked(ncp); 1225 nl = NCP2NEGLIST(ncp); 1226 ns = NCP2NEGSTATE(ncp); 1227 mtx_lock(&nl->nl_lock); 1228 if ((ns->neg_flag & NEG_HOT) != 0) { 1229 TAILQ_REMOVE(&nl->nl_hotlist, ncp, nc_dst); 1230 nl->nl_hotnum--; 1231 } else { 1232 TAILQ_REMOVE(&nl->nl_list, ncp, nc_dst); 1233 } 1234 mtx_unlock(&nl->nl_lock); 1235 atomic_subtract_long(&numneg, 1); 1236 } 1237 1238 static struct neglist * 1239 cache_neg_evict_select_list(void) 1240 { 1241 struct neglist *nl; 1242 u_int c; 1243 1244 c = atomic_fetchadd_int(&neg_cycle, 1) + 1; 1245 nl = &neglists[c % numneglists]; 1246 if (!mtx_trylock(&nl->nl_evict_lock)) { 1247 counter_u64_add(neg_evict_skipped_contended, 1); 1248 return (NULL); 1249 } 1250 return (nl); 1251 } 1252 1253 static struct namecache * 1254 cache_neg_evict_select_entry(struct neglist *nl) 1255 { 1256 struct namecache *ncp, *lncp; 1257 struct negstate *ns, *lns; 1258 int i; 1259 1260 mtx_assert(&nl->nl_evict_lock, MA_OWNED); 1261 mtx_assert(&nl->nl_lock, MA_OWNED); 1262 ncp = TAILQ_FIRST(&nl->nl_list); 1263 if (ncp == NULL) 1264 return (NULL); 1265 lncp = ncp; 1266 lns = NCP2NEGSTATE(lncp); 1267 for (i = 1; i < 4; i++) { 1268 ncp = TAILQ_NEXT(ncp, nc_dst); 1269 if (ncp == NULL) 1270 break; 1271 ns = NCP2NEGSTATE(ncp); 1272 if (ns->neg_hit < lns->neg_hit) { 1273 lncp = ncp; 1274 lns = ns; 1275 } 1276 } 1277 return (lncp); 1278 } 1279 1280 static bool 1281 cache_neg_evict(void) 1282 { 1283 struct namecache *ncp, *ncp2; 1284 struct neglist *nl; 1285 struct vnode *dvp; 1286 struct mtx *dvlp; 1287 struct mtx *blp; 1288 uint32_t hash; 1289 u_char nlen; 1290 bool evicted; 1291 1292 nl = cache_neg_evict_select_list(); 1293 if (nl == NULL) { 1294 return (false); 1295 } 1296 1297 mtx_lock(&nl->nl_lock); 1298 ncp = TAILQ_FIRST(&nl->nl_hotlist); 1299 if (ncp != NULL) { 1300 cache_neg_demote_locked(ncp); 1301 } 1302 ncp = cache_neg_evict_select_entry(nl); 1303 if (ncp == NULL) { 1304 counter_u64_add(neg_evict_skipped_empty, 1); 1305 mtx_unlock(&nl->nl_lock); 1306 mtx_unlock(&nl->nl_evict_lock); 1307 return (false); 1308 } 1309 nlen = ncp->nc_nlen; 1310 dvp = ncp->nc_dvp; 1311 hash = cache_get_hash(ncp->nc_name, nlen, dvp); 1312 dvlp = VP2VNODELOCK(dvp); 1313 blp = HASH2BUCKETLOCK(hash); 1314 mtx_unlock(&nl->nl_lock); 1315 mtx_unlock(&nl->nl_evict_lock); 1316 mtx_lock(dvlp); 1317 mtx_lock(blp); 1318 /* 1319 * Note that since all locks were dropped above, the entry may be 1320 * gone or reallocated to be something else. 1321 */ 1322 CK_SLIST_FOREACH(ncp2, (NCHHASH(hash)), nc_hash) { 1323 if (ncp2 == ncp && ncp2->nc_dvp == dvp && 1324 ncp2->nc_nlen == nlen && (ncp2->nc_flag & NCF_NEGATIVE) != 0) 1325 break; 1326 } 1327 if (ncp2 == NULL) { 1328 counter_u64_add(neg_evict_skipped_missed, 1); 1329 ncp = NULL; 1330 evicted = false; 1331 } else { 1332 MPASS(dvlp == VP2VNODELOCK(ncp->nc_dvp)); 1333 MPASS(blp == NCP2BUCKETLOCK(ncp)); 1334 SDT_PROBE2(vfs, namecache, evict_negative, done, ncp->nc_dvp, 1335 ncp->nc_name); 1336 cache_zap_locked(ncp); 1337 counter_u64_add(neg_evicted, 1); 1338 evicted = true; 1339 } 1340 mtx_unlock(blp); 1341 mtx_unlock(dvlp); 1342 if (ncp != NULL) 1343 cache_free(ncp); 1344 return (evicted); 1345 } 1346 1347 /* 1348 * Maybe evict a negative entry to create more room. 1349 * 1350 * The ncnegfactor parameter limits what fraction of the total count 1351 * can comprise of negative entries. However, if the cache is just 1352 * warming up this leads to excessive evictions. As such, ncnegminpct 1353 * (recomputed to neg_min) dictates whether the above should be 1354 * applied. 1355 * 1356 * Try evicting if the cache is close to full capacity regardless of 1357 * other considerations. 1358 */ 1359 static bool 1360 cache_neg_evict_cond(u_long lnumcache) 1361 { 1362 u_long lnumneg; 1363 1364 if (ncsize - 1000 < lnumcache) 1365 goto out_evict; 1366 lnumneg = atomic_load_long(&numneg); 1367 if (lnumneg < neg_min) 1368 return (false); 1369 if (lnumneg * ncnegfactor < lnumcache) 1370 return (false); 1371 out_evict: 1372 return (cache_neg_evict()); 1373 } 1374 1375 /* 1376 * cache_zap_locked(): 1377 * 1378 * Removes a namecache entry from cache, whether it contains an actual 1379 * pointer to a vnode or if it is just a negative cache entry. 1380 */ 1381 static void 1382 cache_zap_locked(struct namecache *ncp) 1383 { 1384 struct nchashhead *ncpp; 1385 1386 if (!(ncp->nc_flag & NCF_NEGATIVE)) 1387 cache_assert_vnode_locked(ncp->nc_vp); 1388 cache_assert_vnode_locked(ncp->nc_dvp); 1389 cache_assert_bucket_locked(ncp); 1390 1391 cache_ncp_invalidate(ncp); 1392 1393 ncpp = NCP2BUCKET(ncp); 1394 CK_SLIST_REMOVE(ncpp, ncp, namecache, nc_hash); 1395 if (!(ncp->nc_flag & NCF_NEGATIVE)) { 1396 SDT_PROBE3(vfs, namecache, zap, done, ncp->nc_dvp, 1397 ncp->nc_name, ncp->nc_vp); 1398 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst); 1399 if (ncp == ncp->nc_vp->v_cache_dd) { 1400 vn_seqc_write_begin_unheld(ncp->nc_vp); 1401 ncp->nc_vp->v_cache_dd = NULL; 1402 vn_seqc_write_end(ncp->nc_vp); 1403 } 1404 } else { 1405 SDT_PROBE2(vfs, namecache, zap_negative, done, ncp->nc_dvp, 1406 ncp->nc_name); 1407 cache_neg_remove(ncp); 1408 } 1409 if (ncp->nc_flag & NCF_ISDOTDOT) { 1410 if (ncp == ncp->nc_dvp->v_cache_dd) { 1411 vn_seqc_write_begin_unheld(ncp->nc_dvp); 1412 ncp->nc_dvp->v_cache_dd = NULL; 1413 vn_seqc_write_end(ncp->nc_dvp); 1414 } 1415 } else { 1416 LIST_REMOVE(ncp, nc_src); 1417 if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) { 1418 ncp->nc_flag |= NCF_DVDROP; 1419 } 1420 } 1421 } 1422 1423 static void 1424 cache_zap_negative_locked_vnode_kl(struct namecache *ncp, struct vnode *vp) 1425 { 1426 struct mtx *blp; 1427 1428 MPASS(ncp->nc_dvp == vp); 1429 MPASS(ncp->nc_flag & NCF_NEGATIVE); 1430 cache_assert_vnode_locked(vp); 1431 1432 blp = NCP2BUCKETLOCK(ncp); 1433 mtx_lock(blp); 1434 cache_zap_locked(ncp); 1435 mtx_unlock(blp); 1436 } 1437 1438 static bool 1439 cache_zap_locked_vnode_kl2(struct namecache *ncp, struct vnode *vp, 1440 struct mtx **vlpp) 1441 { 1442 struct mtx *pvlp, *vlp1, *vlp2, *to_unlock; 1443 struct mtx *blp; 1444 1445 MPASS(vp == ncp->nc_dvp || vp == ncp->nc_vp); 1446 cache_assert_vnode_locked(vp); 1447 1448 if (ncp->nc_flag & NCF_NEGATIVE) { 1449 if (*vlpp != NULL) { 1450 mtx_unlock(*vlpp); 1451 *vlpp = NULL; 1452 } 1453 cache_zap_negative_locked_vnode_kl(ncp, vp); 1454 return (true); 1455 } 1456 1457 pvlp = VP2VNODELOCK(vp); 1458 blp = NCP2BUCKETLOCK(ncp); 1459 vlp1 = VP2VNODELOCK(ncp->nc_dvp); 1460 vlp2 = VP2VNODELOCK(ncp->nc_vp); 1461 1462 if (*vlpp == vlp1 || *vlpp == vlp2) { 1463 to_unlock = *vlpp; 1464 *vlpp = NULL; 1465 } else { 1466 if (*vlpp != NULL) { 1467 mtx_unlock(*vlpp); 1468 *vlpp = NULL; 1469 } 1470 cache_sort_vnodes(&vlp1, &vlp2); 1471 if (vlp1 == pvlp) { 1472 mtx_lock(vlp2); 1473 to_unlock = vlp2; 1474 } else { 1475 if (!mtx_trylock(vlp1)) 1476 goto out_relock; 1477 to_unlock = vlp1; 1478 } 1479 } 1480 mtx_lock(blp); 1481 cache_zap_locked(ncp); 1482 mtx_unlock(blp); 1483 if (to_unlock != NULL) 1484 mtx_unlock(to_unlock); 1485 return (true); 1486 1487 out_relock: 1488 mtx_unlock(vlp2); 1489 mtx_lock(vlp1); 1490 mtx_lock(vlp2); 1491 MPASS(*vlpp == NULL); 1492 *vlpp = vlp1; 1493 return (false); 1494 } 1495 1496 /* 1497 * If trylocking failed we can get here. We know enough to take all needed locks 1498 * in the right order and re-lookup the entry. 1499 */ 1500 static int 1501 cache_zap_unlocked_bucket(struct namecache *ncp, struct componentname *cnp, 1502 struct vnode *dvp, struct mtx *dvlp, struct mtx *vlp, uint32_t hash, 1503 struct mtx *blp) 1504 { 1505 struct namecache *rncp; 1506 1507 cache_assert_bucket_unlocked(ncp); 1508 1509 cache_sort_vnodes(&dvlp, &vlp); 1510 cache_lock_vnodes(dvlp, vlp); 1511 mtx_lock(blp); 1512 CK_SLIST_FOREACH(rncp, (NCHHASH(hash)), nc_hash) { 1513 if (rncp == ncp && rncp->nc_dvp == dvp && 1514 rncp->nc_nlen == cnp->cn_namelen && 1515 !bcmp(rncp->nc_name, cnp->cn_nameptr, rncp->nc_nlen)) 1516 break; 1517 } 1518 if (rncp != NULL) { 1519 cache_zap_locked(rncp); 1520 mtx_unlock(blp); 1521 cache_unlock_vnodes(dvlp, vlp); 1522 counter_u64_add(zap_bucket_relock_success, 1); 1523 return (0); 1524 } 1525 1526 mtx_unlock(blp); 1527 cache_unlock_vnodes(dvlp, vlp); 1528 return (EAGAIN); 1529 } 1530 1531 static int __noinline 1532 cache_zap_locked_bucket(struct namecache *ncp, struct componentname *cnp, 1533 uint32_t hash, struct mtx *blp) 1534 { 1535 struct mtx *dvlp, *vlp; 1536 struct vnode *dvp; 1537 1538 cache_assert_bucket_locked(ncp); 1539 1540 dvlp = VP2VNODELOCK(ncp->nc_dvp); 1541 vlp = NULL; 1542 if (!(ncp->nc_flag & NCF_NEGATIVE)) 1543 vlp = VP2VNODELOCK(ncp->nc_vp); 1544 if (cache_trylock_vnodes(dvlp, vlp) == 0) { 1545 cache_zap_locked(ncp); 1546 mtx_unlock(blp); 1547 cache_unlock_vnodes(dvlp, vlp); 1548 return (0); 1549 } 1550 1551 dvp = ncp->nc_dvp; 1552 mtx_unlock(blp); 1553 return (cache_zap_unlocked_bucket(ncp, cnp, dvp, dvlp, vlp, hash, blp)); 1554 } 1555 1556 static __noinline int 1557 cache_remove_cnp(struct vnode *dvp, struct componentname *cnp) 1558 { 1559 struct namecache *ncp; 1560 struct mtx *blp; 1561 struct mtx *dvlp, *dvlp2; 1562 uint32_t hash; 1563 int error; 1564 1565 if (cnp->cn_namelen == 2 && 1566 cnp->cn_nameptr[0] == '.' && cnp->cn_nameptr[1] == '.') { 1567 dvlp = VP2VNODELOCK(dvp); 1568 dvlp2 = NULL; 1569 mtx_lock(dvlp); 1570 retry_dotdot: 1571 ncp = dvp->v_cache_dd; 1572 if (ncp == NULL) { 1573 mtx_unlock(dvlp); 1574 if (dvlp2 != NULL) 1575 mtx_unlock(dvlp2); 1576 SDT_PROBE2(vfs, namecache, removecnp, miss, dvp, cnp); 1577 return (0); 1578 } 1579 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) { 1580 if (!cache_zap_locked_vnode_kl2(ncp, dvp, &dvlp2)) 1581 goto retry_dotdot; 1582 MPASS(dvp->v_cache_dd == NULL); 1583 mtx_unlock(dvlp); 1584 if (dvlp2 != NULL) 1585 mtx_unlock(dvlp2); 1586 cache_free(ncp); 1587 } else { 1588 vn_seqc_write_begin(dvp); 1589 dvp->v_cache_dd = NULL; 1590 vn_seqc_write_end(dvp); 1591 mtx_unlock(dvlp); 1592 if (dvlp2 != NULL) 1593 mtx_unlock(dvlp2); 1594 } 1595 SDT_PROBE2(vfs, namecache, removecnp, hit, dvp, cnp); 1596 return (1); 1597 } 1598 1599 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp); 1600 blp = HASH2BUCKETLOCK(hash); 1601 retry: 1602 if (CK_SLIST_EMPTY(NCHHASH(hash))) 1603 goto out_no_entry; 1604 1605 mtx_lock(blp); 1606 1607 CK_SLIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 1608 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 1609 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 1610 break; 1611 } 1612 1613 if (ncp == NULL) { 1614 mtx_unlock(blp); 1615 goto out_no_entry; 1616 } 1617 1618 error = cache_zap_locked_bucket(ncp, cnp, hash, blp); 1619 if (__predict_false(error != 0)) { 1620 zap_bucket_fail++; 1621 goto retry; 1622 } 1623 counter_u64_add(numposzaps, 1); 1624 SDT_PROBE2(vfs, namecache, removecnp, hit, dvp, cnp); 1625 cache_free(ncp); 1626 return (1); 1627 out_no_entry: 1628 counter_u64_add(nummisszap, 1); 1629 SDT_PROBE2(vfs, namecache, removecnp, miss, dvp, cnp); 1630 return (0); 1631 } 1632 1633 static int __noinline 1634 cache_lookup_dot(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, 1635 struct timespec *tsp, int *ticksp) 1636 { 1637 int ltype; 1638 1639 *vpp = dvp; 1640 counter_u64_add(dothits, 1); 1641 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ".", *vpp); 1642 if (tsp != NULL) 1643 timespecclear(tsp); 1644 if (ticksp != NULL) 1645 *ticksp = ticks; 1646 vrefact(*vpp); 1647 /* 1648 * When we lookup "." we still can be asked to lock it 1649 * differently... 1650 */ 1651 ltype = cnp->cn_lkflags & LK_TYPE_MASK; 1652 if (ltype != VOP_ISLOCKED(*vpp)) { 1653 if (ltype == LK_EXCLUSIVE) { 1654 vn_lock(*vpp, LK_UPGRADE | LK_RETRY); 1655 if (VN_IS_DOOMED((*vpp))) { 1656 /* forced unmount */ 1657 vrele(*vpp); 1658 *vpp = NULL; 1659 return (ENOENT); 1660 } 1661 } else 1662 vn_lock(*vpp, LK_DOWNGRADE | LK_RETRY); 1663 } 1664 return (-1); 1665 } 1666 1667 static int __noinline 1668 cache_lookup_dotdot(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, 1669 struct timespec *tsp, int *ticksp) 1670 { 1671 struct namecache_ts *ncp_ts; 1672 struct namecache *ncp; 1673 struct mtx *dvlp; 1674 enum vgetstate vs; 1675 int error, ltype; 1676 bool whiteout; 1677 1678 MPASS((cnp->cn_flags & ISDOTDOT) != 0); 1679 1680 if ((cnp->cn_flags & MAKEENTRY) == 0) { 1681 cache_remove_cnp(dvp, cnp); 1682 return (0); 1683 } 1684 1685 counter_u64_add(dotdothits, 1); 1686 retry: 1687 dvlp = VP2VNODELOCK(dvp); 1688 mtx_lock(dvlp); 1689 ncp = dvp->v_cache_dd; 1690 if (ncp == NULL) { 1691 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, "..", NULL); 1692 mtx_unlock(dvlp); 1693 return (0); 1694 } 1695 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) { 1696 if (ncp->nc_flag & NCF_NEGATIVE) 1697 *vpp = NULL; 1698 else 1699 *vpp = ncp->nc_vp; 1700 } else 1701 *vpp = ncp->nc_dvp; 1702 if (*vpp == NULL) 1703 goto negative_success; 1704 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, "..", *vpp); 1705 cache_out_ts(ncp, tsp, ticksp); 1706 if ((ncp->nc_flag & (NCF_ISDOTDOT | NCF_DTS)) == 1707 NCF_DTS && tsp != NULL) { 1708 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); 1709 *tsp = ncp_ts->nc_dotdottime; 1710 } 1711 1712 MPASS(dvp != *vpp); 1713 ltype = VOP_ISLOCKED(dvp); 1714 VOP_UNLOCK(dvp); 1715 vs = vget_prep(*vpp); 1716 mtx_unlock(dvlp); 1717 error = vget_finish(*vpp, cnp->cn_lkflags, vs); 1718 vn_lock(dvp, ltype | LK_RETRY); 1719 if (VN_IS_DOOMED(dvp)) { 1720 if (error == 0) 1721 vput(*vpp); 1722 *vpp = NULL; 1723 return (ENOENT); 1724 } 1725 if (error) { 1726 *vpp = NULL; 1727 goto retry; 1728 } 1729 return (-1); 1730 negative_success: 1731 if (__predict_false(cnp->cn_nameiop == CREATE)) { 1732 if (cnp->cn_flags & ISLASTCN) { 1733 counter_u64_add(numnegzaps, 1); 1734 cache_zap_negative_locked_vnode_kl(ncp, dvp); 1735 mtx_unlock(dvlp); 1736 cache_free(ncp); 1737 return (0); 1738 } 1739 } 1740 1741 whiteout = (ncp->nc_flag & NCF_WHITE); 1742 cache_out_ts(ncp, tsp, ticksp); 1743 if (cache_neg_hit_prep(ncp)) 1744 cache_neg_promote(ncp); 1745 else 1746 cache_neg_hit_finish(ncp); 1747 mtx_unlock(dvlp); 1748 if (whiteout) 1749 cnp->cn_flags |= ISWHITEOUT; 1750 return (ENOENT); 1751 } 1752 1753 /** 1754 * Lookup a name in the name cache 1755 * 1756 * # Arguments 1757 * 1758 * - dvp: Parent directory in which to search. 1759 * - vpp: Return argument. Will contain desired vnode on cache hit. 1760 * - cnp: Parameters of the name search. The most interesting bits of 1761 * the cn_flags field have the following meanings: 1762 * - MAKEENTRY: If clear, free an entry from the cache rather than look 1763 * it up. 1764 * - ISDOTDOT: Must be set if and only if cn_nameptr == ".." 1765 * - tsp: Return storage for cache timestamp. On a successful (positive 1766 * or negative) lookup, tsp will be filled with any timespec that 1767 * was stored when this cache entry was created. However, it will 1768 * be clear for "." entries. 1769 * - ticks: Return storage for alternate cache timestamp. On a successful 1770 * (positive or negative) lookup, it will contain the ticks value 1771 * that was current when the cache entry was created, unless cnp 1772 * was ".". 1773 * 1774 * Either both tsp and ticks have to be provided or neither of them. 1775 * 1776 * # Returns 1777 * 1778 * - -1: A positive cache hit. vpp will contain the desired vnode. 1779 * - ENOENT: A negative cache hit, or dvp was recycled out from under us due 1780 * to a forced unmount. vpp will not be modified. If the entry 1781 * is a whiteout, then the ISWHITEOUT flag will be set in 1782 * cnp->cn_flags. 1783 * - 0: A cache miss. vpp will not be modified. 1784 * 1785 * # Locking 1786 * 1787 * On a cache hit, vpp will be returned locked and ref'd. If we're looking up 1788 * .., dvp is unlocked. If we're looking up . an extra ref is taken, but the 1789 * lock is not recursively acquired. 1790 */ 1791 static int __noinline 1792 cache_lookup_fallback(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, 1793 struct timespec *tsp, int *ticksp) 1794 { 1795 struct namecache *ncp; 1796 struct mtx *blp; 1797 uint32_t hash; 1798 enum vgetstate vs; 1799 int error; 1800 bool whiteout; 1801 1802 MPASS((cnp->cn_flags & ISDOTDOT) == 0); 1803 MPASS((cnp->cn_flags & (MAKEENTRY | NC_KEEPPOSENTRY)) != 0); 1804 1805 retry: 1806 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp); 1807 blp = HASH2BUCKETLOCK(hash); 1808 mtx_lock(blp); 1809 1810 CK_SLIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 1811 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 1812 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 1813 break; 1814 } 1815 1816 if (__predict_false(ncp == NULL)) { 1817 mtx_unlock(blp); 1818 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr, 1819 NULL); 1820 counter_u64_add(nummiss, 1); 1821 return (0); 1822 } 1823 1824 if (ncp->nc_flag & NCF_NEGATIVE) 1825 goto negative_success; 1826 1827 counter_u64_add(numposhits, 1); 1828 *vpp = ncp->nc_vp; 1829 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ncp->nc_name, *vpp); 1830 cache_out_ts(ncp, tsp, ticksp); 1831 MPASS(dvp != *vpp); 1832 vs = vget_prep(*vpp); 1833 mtx_unlock(blp); 1834 error = vget_finish(*vpp, cnp->cn_lkflags, vs); 1835 if (error) { 1836 *vpp = NULL; 1837 goto retry; 1838 } 1839 return (-1); 1840 negative_success: 1841 /* 1842 * We don't get here with regular lookup apart from corner cases. 1843 */ 1844 if (__predict_true(cnp->cn_nameiop == CREATE)) { 1845 if (cnp->cn_flags & ISLASTCN) { 1846 counter_u64_add(numnegzaps, 1); 1847 error = cache_zap_locked_bucket(ncp, cnp, hash, blp); 1848 if (__predict_false(error != 0)) { 1849 zap_bucket_fail2++; 1850 goto retry; 1851 } 1852 cache_free(ncp); 1853 return (0); 1854 } 1855 } 1856 1857 whiteout = (ncp->nc_flag & NCF_WHITE); 1858 cache_out_ts(ncp, tsp, ticksp); 1859 if (cache_neg_hit_prep(ncp)) 1860 cache_neg_promote(ncp); 1861 else 1862 cache_neg_hit_finish(ncp); 1863 mtx_unlock(blp); 1864 if (whiteout) 1865 cnp->cn_flags |= ISWHITEOUT; 1866 return (ENOENT); 1867 } 1868 1869 int 1870 cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, 1871 struct timespec *tsp, int *ticksp) 1872 { 1873 struct namecache *ncp; 1874 uint32_t hash; 1875 enum vgetstate vs; 1876 int error; 1877 bool whiteout, neg_promote; 1878 u_short nc_flag; 1879 1880 MPASS((tsp == NULL && ticksp == NULL) || (tsp != NULL && ticksp != NULL)); 1881 1882 #ifdef DEBUG_CACHE 1883 if (__predict_false(!doingcache)) { 1884 cnp->cn_flags &= ~MAKEENTRY; 1885 return (0); 1886 } 1887 #endif 1888 1889 if (__predict_false(cnp->cn_nameptr[0] == '.')) { 1890 if (cnp->cn_namelen == 1) 1891 return (cache_lookup_dot(dvp, vpp, cnp, tsp, ticksp)); 1892 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') 1893 return (cache_lookup_dotdot(dvp, vpp, cnp, tsp, ticksp)); 1894 } 1895 1896 MPASS((cnp->cn_flags & ISDOTDOT) == 0); 1897 1898 if ((cnp->cn_flags & (MAKEENTRY | NC_KEEPPOSENTRY)) == 0) { 1899 cache_remove_cnp(dvp, cnp); 1900 return (0); 1901 } 1902 1903 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp); 1904 vfs_smr_enter(); 1905 1906 CK_SLIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 1907 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 1908 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 1909 break; 1910 } 1911 1912 if (__predict_false(ncp == NULL)) { 1913 vfs_smr_exit(); 1914 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr, 1915 NULL); 1916 counter_u64_add(nummiss, 1); 1917 return (0); 1918 } 1919 1920 nc_flag = atomic_load_char(&ncp->nc_flag); 1921 if (nc_flag & NCF_NEGATIVE) 1922 goto negative_success; 1923 1924 counter_u64_add(numposhits, 1); 1925 *vpp = ncp->nc_vp; 1926 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ncp->nc_name, *vpp); 1927 cache_out_ts(ncp, tsp, ticksp); 1928 MPASS(dvp != *vpp); 1929 if (!cache_ncp_canuse(ncp)) { 1930 vfs_smr_exit(); 1931 *vpp = NULL; 1932 goto out_fallback; 1933 } 1934 vs = vget_prep_smr(*vpp); 1935 vfs_smr_exit(); 1936 if (__predict_false(vs == VGET_NONE)) { 1937 *vpp = NULL; 1938 goto out_fallback; 1939 } 1940 error = vget_finish(*vpp, cnp->cn_lkflags, vs); 1941 if (error) { 1942 *vpp = NULL; 1943 goto out_fallback; 1944 } 1945 return (-1); 1946 negative_success: 1947 if (cnp->cn_nameiop == CREATE) { 1948 if (cnp->cn_flags & ISLASTCN) { 1949 vfs_smr_exit(); 1950 goto out_fallback; 1951 } 1952 } 1953 1954 cache_out_ts(ncp, tsp, ticksp); 1955 whiteout = (ncp->nc_flag & NCF_WHITE); 1956 neg_promote = cache_neg_hit_prep(ncp); 1957 if (!cache_ncp_canuse(ncp)) { 1958 cache_neg_hit_abort(ncp); 1959 vfs_smr_exit(); 1960 goto out_fallback; 1961 } 1962 if (neg_promote) { 1963 vfs_smr_exit(); 1964 if (!cache_neg_promote_cond(dvp, cnp, ncp, hash)) 1965 goto out_fallback; 1966 } else { 1967 cache_neg_hit_finish(ncp); 1968 vfs_smr_exit(); 1969 } 1970 if (whiteout) 1971 cnp->cn_flags |= ISWHITEOUT; 1972 return (ENOENT); 1973 out_fallback: 1974 return (cache_lookup_fallback(dvp, vpp, cnp, tsp, ticksp)); 1975 } 1976 1977 struct celockstate { 1978 struct mtx *vlp[3]; 1979 struct mtx *blp[2]; 1980 }; 1981 CTASSERT((nitems(((struct celockstate *)0)->vlp) == 3)); 1982 CTASSERT((nitems(((struct celockstate *)0)->blp) == 2)); 1983 1984 static inline void 1985 cache_celockstate_init(struct celockstate *cel) 1986 { 1987 1988 bzero(cel, sizeof(*cel)); 1989 } 1990 1991 static void 1992 cache_lock_vnodes_cel(struct celockstate *cel, struct vnode *vp, 1993 struct vnode *dvp) 1994 { 1995 struct mtx *vlp1, *vlp2; 1996 1997 MPASS(cel->vlp[0] == NULL); 1998 MPASS(cel->vlp[1] == NULL); 1999 MPASS(cel->vlp[2] == NULL); 2000 2001 MPASS(vp != NULL || dvp != NULL); 2002 2003 vlp1 = VP2VNODELOCK(vp); 2004 vlp2 = VP2VNODELOCK(dvp); 2005 cache_sort_vnodes(&vlp1, &vlp2); 2006 2007 if (vlp1 != NULL) { 2008 mtx_lock(vlp1); 2009 cel->vlp[0] = vlp1; 2010 } 2011 mtx_lock(vlp2); 2012 cel->vlp[1] = vlp2; 2013 } 2014 2015 static void 2016 cache_unlock_vnodes_cel(struct celockstate *cel) 2017 { 2018 2019 MPASS(cel->vlp[0] != NULL || cel->vlp[1] != NULL); 2020 2021 if (cel->vlp[0] != NULL) 2022 mtx_unlock(cel->vlp[0]); 2023 if (cel->vlp[1] != NULL) 2024 mtx_unlock(cel->vlp[1]); 2025 if (cel->vlp[2] != NULL) 2026 mtx_unlock(cel->vlp[2]); 2027 } 2028 2029 static bool 2030 cache_lock_vnodes_cel_3(struct celockstate *cel, struct vnode *vp) 2031 { 2032 struct mtx *vlp; 2033 bool ret; 2034 2035 cache_assert_vlp_locked(cel->vlp[0]); 2036 cache_assert_vlp_locked(cel->vlp[1]); 2037 MPASS(cel->vlp[2] == NULL); 2038 2039 MPASS(vp != NULL); 2040 vlp = VP2VNODELOCK(vp); 2041 2042 ret = true; 2043 if (vlp >= cel->vlp[1]) { 2044 mtx_lock(vlp); 2045 } else { 2046 if (mtx_trylock(vlp)) 2047 goto out; 2048 cache_lock_vnodes_cel_3_failures++; 2049 cache_unlock_vnodes_cel(cel); 2050 if (vlp < cel->vlp[0]) { 2051 mtx_lock(vlp); 2052 mtx_lock(cel->vlp[0]); 2053 mtx_lock(cel->vlp[1]); 2054 } else { 2055 if (cel->vlp[0] != NULL) 2056 mtx_lock(cel->vlp[0]); 2057 mtx_lock(vlp); 2058 mtx_lock(cel->vlp[1]); 2059 } 2060 ret = false; 2061 } 2062 out: 2063 cel->vlp[2] = vlp; 2064 return (ret); 2065 } 2066 2067 static void 2068 cache_lock_buckets_cel(struct celockstate *cel, struct mtx *blp1, 2069 struct mtx *blp2) 2070 { 2071 2072 MPASS(cel->blp[0] == NULL); 2073 MPASS(cel->blp[1] == NULL); 2074 2075 cache_sort_vnodes(&blp1, &blp2); 2076 2077 if (blp1 != NULL) { 2078 mtx_lock(blp1); 2079 cel->blp[0] = blp1; 2080 } 2081 mtx_lock(blp2); 2082 cel->blp[1] = blp2; 2083 } 2084 2085 static void 2086 cache_unlock_buckets_cel(struct celockstate *cel) 2087 { 2088 2089 if (cel->blp[0] != NULL) 2090 mtx_unlock(cel->blp[0]); 2091 mtx_unlock(cel->blp[1]); 2092 } 2093 2094 /* 2095 * Lock part of the cache affected by the insertion. 2096 * 2097 * This means vnodelocks for dvp, vp and the relevant bucketlock. 2098 * However, insertion can result in removal of an old entry. In this 2099 * case we have an additional vnode and bucketlock pair to lock. 2100 * 2101 * That is, in the worst case we have to lock 3 vnodes and 2 bucketlocks, while 2102 * preserving the locking order (smaller address first). 2103 */ 2104 static void 2105 cache_enter_lock(struct celockstate *cel, struct vnode *dvp, struct vnode *vp, 2106 uint32_t hash) 2107 { 2108 struct namecache *ncp; 2109 struct mtx *blps[2]; 2110 2111 blps[0] = HASH2BUCKETLOCK(hash); 2112 for (;;) { 2113 blps[1] = NULL; 2114 cache_lock_vnodes_cel(cel, dvp, vp); 2115 if (vp == NULL || vp->v_type != VDIR) 2116 break; 2117 ncp = vp->v_cache_dd; 2118 if (ncp == NULL) 2119 break; 2120 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 2121 break; 2122 MPASS(ncp->nc_dvp == vp); 2123 blps[1] = NCP2BUCKETLOCK(ncp); 2124 if (ncp->nc_flag & NCF_NEGATIVE) 2125 break; 2126 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp)) 2127 break; 2128 /* 2129 * All vnodes got re-locked. Re-validate the state and if 2130 * nothing changed we are done. Otherwise restart. 2131 */ 2132 if (ncp == vp->v_cache_dd && 2133 (ncp->nc_flag & NCF_ISDOTDOT) != 0 && 2134 blps[1] == NCP2BUCKETLOCK(ncp) && 2135 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2]) 2136 break; 2137 cache_unlock_vnodes_cel(cel); 2138 cel->vlp[0] = NULL; 2139 cel->vlp[1] = NULL; 2140 cel->vlp[2] = NULL; 2141 } 2142 cache_lock_buckets_cel(cel, blps[0], blps[1]); 2143 } 2144 2145 static void 2146 cache_enter_lock_dd(struct celockstate *cel, struct vnode *dvp, struct vnode *vp, 2147 uint32_t hash) 2148 { 2149 struct namecache *ncp; 2150 struct mtx *blps[2]; 2151 2152 blps[0] = HASH2BUCKETLOCK(hash); 2153 for (;;) { 2154 blps[1] = NULL; 2155 cache_lock_vnodes_cel(cel, dvp, vp); 2156 ncp = dvp->v_cache_dd; 2157 if (ncp == NULL) 2158 break; 2159 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 2160 break; 2161 MPASS(ncp->nc_dvp == dvp); 2162 blps[1] = NCP2BUCKETLOCK(ncp); 2163 if (ncp->nc_flag & NCF_NEGATIVE) 2164 break; 2165 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp)) 2166 break; 2167 if (ncp == dvp->v_cache_dd && 2168 (ncp->nc_flag & NCF_ISDOTDOT) != 0 && 2169 blps[1] == NCP2BUCKETLOCK(ncp) && 2170 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2]) 2171 break; 2172 cache_unlock_vnodes_cel(cel); 2173 cel->vlp[0] = NULL; 2174 cel->vlp[1] = NULL; 2175 cel->vlp[2] = NULL; 2176 } 2177 cache_lock_buckets_cel(cel, blps[0], blps[1]); 2178 } 2179 2180 static void 2181 cache_enter_unlock(struct celockstate *cel) 2182 { 2183 2184 cache_unlock_buckets_cel(cel); 2185 cache_unlock_vnodes_cel(cel); 2186 } 2187 2188 static void __noinline 2189 cache_enter_dotdot_prep(struct vnode *dvp, struct vnode *vp, 2190 struct componentname *cnp) 2191 { 2192 struct celockstate cel; 2193 struct namecache *ncp; 2194 uint32_t hash; 2195 int len; 2196 2197 if (dvp->v_cache_dd == NULL) 2198 return; 2199 len = cnp->cn_namelen; 2200 cache_celockstate_init(&cel); 2201 hash = cache_get_hash(cnp->cn_nameptr, len, dvp); 2202 cache_enter_lock_dd(&cel, dvp, vp, hash); 2203 vn_seqc_write_begin(dvp); 2204 ncp = dvp->v_cache_dd; 2205 if (ncp != NULL && (ncp->nc_flag & NCF_ISDOTDOT)) { 2206 KASSERT(ncp->nc_dvp == dvp, ("wrong isdotdot parent")); 2207 cache_zap_locked(ncp); 2208 } else { 2209 ncp = NULL; 2210 } 2211 dvp->v_cache_dd = NULL; 2212 vn_seqc_write_end(dvp); 2213 cache_enter_unlock(&cel); 2214 if (ncp != NULL) 2215 cache_free(ncp); 2216 } 2217 2218 /* 2219 * Add an entry to the cache. 2220 */ 2221 void 2222 cache_enter_time(struct vnode *dvp, struct vnode *vp, struct componentname *cnp, 2223 struct timespec *tsp, struct timespec *dtsp) 2224 { 2225 struct celockstate cel; 2226 struct namecache *ncp, *n2, *ndd; 2227 struct namecache_ts *ncp_ts; 2228 struct nchashhead *ncpp; 2229 uint32_t hash; 2230 int flag; 2231 int len; 2232 2233 KASSERT(cnp->cn_namelen <= NAME_MAX, 2234 ("%s: passed len %ld exceeds NAME_MAX (%d)", __func__, cnp->cn_namelen, 2235 NAME_MAX)); 2236 VNPASS(dvp != vp, dvp); 2237 VNPASS(!VN_IS_DOOMED(dvp), dvp); 2238 VNPASS(dvp->v_type != VNON, dvp); 2239 if (vp != NULL) { 2240 VNPASS(!VN_IS_DOOMED(vp), vp); 2241 VNPASS(vp->v_type != VNON, vp); 2242 } 2243 2244 #ifdef DEBUG_CACHE 2245 if (__predict_false(!doingcache)) 2246 return; 2247 #endif 2248 2249 flag = 0; 2250 if (__predict_false(cnp->cn_nameptr[0] == '.')) { 2251 if (cnp->cn_namelen == 1) 2252 return; 2253 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 2254 cache_enter_dotdot_prep(dvp, vp, cnp); 2255 flag = NCF_ISDOTDOT; 2256 } 2257 } 2258 2259 ncp = cache_alloc(cnp->cn_namelen, tsp != NULL); 2260 if (ncp == NULL) 2261 return; 2262 2263 cache_celockstate_init(&cel); 2264 ndd = NULL; 2265 ncp_ts = NULL; 2266 2267 /* 2268 * Calculate the hash key and setup as much of the new 2269 * namecache entry as possible before acquiring the lock. 2270 */ 2271 ncp->nc_flag = flag | NCF_WIP; 2272 ncp->nc_vp = vp; 2273 if (vp == NULL) 2274 cache_neg_init(ncp); 2275 ncp->nc_dvp = dvp; 2276 if (tsp != NULL) { 2277 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); 2278 ncp_ts->nc_time = *tsp; 2279 ncp_ts->nc_ticks = ticks; 2280 ncp_ts->nc_nc.nc_flag |= NCF_TS; 2281 if (dtsp != NULL) { 2282 ncp_ts->nc_dotdottime = *dtsp; 2283 ncp_ts->nc_nc.nc_flag |= NCF_DTS; 2284 } 2285 } 2286 len = ncp->nc_nlen = cnp->cn_namelen; 2287 hash = cache_get_hash(cnp->cn_nameptr, len, dvp); 2288 memcpy(ncp->nc_name, cnp->cn_nameptr, len); 2289 ncp->nc_name[len] = '\0'; 2290 cache_enter_lock(&cel, dvp, vp, hash); 2291 2292 /* 2293 * See if this vnode or negative entry is already in the cache 2294 * with this name. This can happen with concurrent lookups of 2295 * the same path name. 2296 */ 2297 ncpp = NCHHASH(hash); 2298 CK_SLIST_FOREACH(n2, ncpp, nc_hash) { 2299 if (n2->nc_dvp == dvp && 2300 n2->nc_nlen == cnp->cn_namelen && 2301 !bcmp(n2->nc_name, cnp->cn_nameptr, n2->nc_nlen)) { 2302 MPASS(cache_ncp_canuse(n2)); 2303 if ((n2->nc_flag & NCF_NEGATIVE) != 0) 2304 KASSERT(vp == NULL, 2305 ("%s: found entry pointing to a different vnode (%p != %p)", 2306 __func__, NULL, vp)); 2307 else 2308 KASSERT(n2->nc_vp == vp, 2309 ("%s: found entry pointing to a different vnode (%p != %p)", 2310 __func__, n2->nc_vp, vp)); 2311 /* 2312 * Entries are supposed to be immutable unless in the 2313 * process of getting destroyed. Accommodating for 2314 * changing timestamps is possible but not worth it. 2315 * This should be harmless in terms of correctness, in 2316 * the worst case resulting in an earlier expiration. 2317 * Alternatively, the found entry can be replaced 2318 * altogether. 2319 */ 2320 MPASS((n2->nc_flag & (NCF_TS | NCF_DTS)) == (ncp->nc_flag & (NCF_TS | NCF_DTS))); 2321 #if 0 2322 if (tsp != NULL) { 2323 KASSERT((n2->nc_flag & NCF_TS) != 0, 2324 ("no NCF_TS")); 2325 n2_ts = __containerof(n2, struct namecache_ts, nc_nc); 2326 n2_ts->nc_time = ncp_ts->nc_time; 2327 n2_ts->nc_ticks = ncp_ts->nc_ticks; 2328 if (dtsp != NULL) { 2329 n2_ts->nc_dotdottime = ncp_ts->nc_dotdottime; 2330 n2_ts->nc_nc.nc_flag |= NCF_DTS; 2331 } 2332 } 2333 #endif 2334 SDT_PROBE3(vfs, namecache, enter, duplicate, dvp, ncp->nc_name, 2335 vp); 2336 goto out_unlock_free; 2337 } 2338 } 2339 2340 if (flag == NCF_ISDOTDOT) { 2341 /* 2342 * See if we are trying to add .. entry, but some other lookup 2343 * has populated v_cache_dd pointer already. 2344 */ 2345 if (dvp->v_cache_dd != NULL) 2346 goto out_unlock_free; 2347 KASSERT(vp == NULL || vp->v_type == VDIR, 2348 ("wrong vnode type %p", vp)); 2349 vn_seqc_write_begin(dvp); 2350 dvp->v_cache_dd = ncp; 2351 vn_seqc_write_end(dvp); 2352 } 2353 2354 if (vp != NULL) { 2355 if (flag != NCF_ISDOTDOT) { 2356 /* 2357 * For this case, the cache entry maps both the 2358 * directory name in it and the name ".." for the 2359 * directory's parent. 2360 */ 2361 vn_seqc_write_begin(vp); 2362 if ((ndd = vp->v_cache_dd) != NULL) { 2363 if ((ndd->nc_flag & NCF_ISDOTDOT) != 0) 2364 cache_zap_locked(ndd); 2365 else 2366 ndd = NULL; 2367 } 2368 vp->v_cache_dd = ncp; 2369 vn_seqc_write_end(vp); 2370 } else if (vp->v_type != VDIR) { 2371 if (vp->v_cache_dd != NULL) { 2372 vn_seqc_write_begin(vp); 2373 vp->v_cache_dd = NULL; 2374 vn_seqc_write_end(vp); 2375 } 2376 } 2377 } 2378 2379 if (flag != NCF_ISDOTDOT) { 2380 if (LIST_EMPTY(&dvp->v_cache_src)) { 2381 cache_hold_vnode(dvp); 2382 } 2383 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); 2384 } 2385 2386 /* 2387 * If the entry is "negative", we place it into the 2388 * "negative" cache queue, otherwise, we place it into the 2389 * destination vnode's cache entries queue. 2390 */ 2391 if (vp != NULL) { 2392 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); 2393 SDT_PROBE3(vfs, namecache, enter, done, dvp, ncp->nc_name, 2394 vp); 2395 } else { 2396 if (cnp->cn_flags & ISWHITEOUT) 2397 ncp->nc_flag |= NCF_WHITE; 2398 cache_neg_insert(ncp); 2399 SDT_PROBE2(vfs, namecache, enter_negative, done, dvp, 2400 ncp->nc_name); 2401 } 2402 2403 /* 2404 * Insert the new namecache entry into the appropriate chain 2405 * within the cache entries table. 2406 */ 2407 CK_SLIST_INSERT_HEAD(ncpp, ncp, nc_hash); 2408 2409 atomic_thread_fence_rel(); 2410 /* 2411 * Mark the entry as fully constructed. 2412 * It is immutable past this point until its removal. 2413 */ 2414 atomic_store_char(&ncp->nc_flag, ncp->nc_flag & ~NCF_WIP); 2415 2416 cache_enter_unlock(&cel); 2417 if (ndd != NULL) 2418 cache_free(ndd); 2419 return; 2420 out_unlock_free: 2421 cache_enter_unlock(&cel); 2422 cache_free(ncp); 2423 return; 2424 } 2425 2426 static u_int 2427 cache_roundup_2(u_int val) 2428 { 2429 u_int res; 2430 2431 for (res = 1; res <= val; res <<= 1) 2432 continue; 2433 2434 return (res); 2435 } 2436 2437 static struct nchashhead * 2438 nchinittbl(u_long elements, u_long *hashmask) 2439 { 2440 struct nchashhead *hashtbl; 2441 u_long hashsize, i; 2442 2443 hashsize = cache_roundup_2(elements) / 2; 2444 2445 hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), M_VFSCACHE, M_WAITOK); 2446 for (i = 0; i < hashsize; i++) 2447 CK_SLIST_INIT(&hashtbl[i]); 2448 *hashmask = hashsize - 1; 2449 return (hashtbl); 2450 } 2451 2452 static void 2453 ncfreetbl(struct nchashhead *hashtbl) 2454 { 2455 2456 free(hashtbl, M_VFSCACHE); 2457 } 2458 2459 /* 2460 * Name cache initialization, from vfs_init() when we are booting 2461 */ 2462 static void 2463 nchinit(void *dummy __unused) 2464 { 2465 u_int i; 2466 2467 cache_zone_small = uma_zcreate("S VFS Cache", CACHE_ZONE_SMALL_SIZE, 2468 NULL, NULL, NULL, NULL, CACHE_ZONE_ALIGNMENT, UMA_ZONE_ZINIT); 2469 cache_zone_small_ts = uma_zcreate("STS VFS Cache", CACHE_ZONE_SMALL_TS_SIZE, 2470 NULL, NULL, NULL, NULL, CACHE_ZONE_ALIGNMENT, UMA_ZONE_ZINIT); 2471 cache_zone_large = uma_zcreate("L VFS Cache", CACHE_ZONE_LARGE_SIZE, 2472 NULL, NULL, NULL, NULL, CACHE_ZONE_ALIGNMENT, UMA_ZONE_ZINIT); 2473 cache_zone_large_ts = uma_zcreate("LTS VFS Cache", CACHE_ZONE_LARGE_TS_SIZE, 2474 NULL, NULL, NULL, NULL, CACHE_ZONE_ALIGNMENT, UMA_ZONE_ZINIT); 2475 2476 VFS_SMR_ZONE_SET(cache_zone_small); 2477 VFS_SMR_ZONE_SET(cache_zone_small_ts); 2478 VFS_SMR_ZONE_SET(cache_zone_large); 2479 VFS_SMR_ZONE_SET(cache_zone_large_ts); 2480 2481 ncsize = desiredvnodes * ncsizefactor; 2482 cache_recalc_neg_min(ncnegminpct); 2483 nchashtbl = nchinittbl(desiredvnodes * 2, &nchash); 2484 ncbuckethash = cache_roundup_2(mp_ncpus * mp_ncpus) - 1; 2485 if (ncbuckethash < 7) /* arbitrarily chosen to avoid having one lock */ 2486 ncbuckethash = 7; 2487 if (ncbuckethash > nchash) 2488 ncbuckethash = nchash; 2489 bucketlocks = malloc(sizeof(*bucketlocks) * numbucketlocks, M_VFSCACHE, 2490 M_WAITOK | M_ZERO); 2491 for (i = 0; i < numbucketlocks; i++) 2492 mtx_init(&bucketlocks[i], "ncbuc", NULL, MTX_DUPOK | MTX_RECURSE); 2493 ncvnodehash = ncbuckethash; 2494 vnodelocks = malloc(sizeof(*vnodelocks) * numvnodelocks, M_VFSCACHE, 2495 M_WAITOK | M_ZERO); 2496 for (i = 0; i < numvnodelocks; i++) 2497 mtx_init(&vnodelocks[i], "ncvn", NULL, MTX_DUPOK | MTX_RECURSE); 2498 2499 for (i = 0; i < numneglists; i++) { 2500 mtx_init(&neglists[i].nl_evict_lock, "ncnege", NULL, MTX_DEF); 2501 mtx_init(&neglists[i].nl_lock, "ncnegl", NULL, MTX_DEF); 2502 TAILQ_INIT(&neglists[i].nl_list); 2503 TAILQ_INIT(&neglists[i].nl_hotlist); 2504 } 2505 } 2506 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL); 2507 2508 void 2509 cache_vnode_init(struct vnode *vp) 2510 { 2511 2512 LIST_INIT(&vp->v_cache_src); 2513 TAILQ_INIT(&vp->v_cache_dst); 2514 vp->v_cache_dd = NULL; 2515 cache_prehash(vp); 2516 } 2517 2518 void 2519 cache_changesize(u_long newmaxvnodes) 2520 { 2521 struct nchashhead *new_nchashtbl, *old_nchashtbl; 2522 u_long new_nchash, old_nchash; 2523 struct namecache *ncp; 2524 uint32_t hash; 2525 u_long newncsize; 2526 int i; 2527 2528 newncsize = newmaxvnodes * ncsizefactor; 2529 newmaxvnodes = cache_roundup_2(newmaxvnodes * 2); 2530 if (newmaxvnodes < numbucketlocks) 2531 newmaxvnodes = numbucketlocks; 2532 2533 new_nchashtbl = nchinittbl(newmaxvnodes, &new_nchash); 2534 /* If same hash table size, nothing to do */ 2535 if (nchash == new_nchash) { 2536 ncfreetbl(new_nchashtbl); 2537 return; 2538 } 2539 /* 2540 * Move everything from the old hash table to the new table. 2541 * None of the namecache entries in the table can be removed 2542 * because to do so, they have to be removed from the hash table. 2543 */ 2544 cache_lock_all_vnodes(); 2545 cache_lock_all_buckets(); 2546 old_nchashtbl = nchashtbl; 2547 old_nchash = nchash; 2548 nchashtbl = new_nchashtbl; 2549 nchash = new_nchash; 2550 for (i = 0; i <= old_nchash; i++) { 2551 while ((ncp = CK_SLIST_FIRST(&old_nchashtbl[i])) != NULL) { 2552 hash = cache_get_hash(ncp->nc_name, ncp->nc_nlen, 2553 ncp->nc_dvp); 2554 CK_SLIST_REMOVE(&old_nchashtbl[i], ncp, namecache, nc_hash); 2555 CK_SLIST_INSERT_HEAD(NCHHASH(hash), ncp, nc_hash); 2556 } 2557 } 2558 ncsize = newncsize; 2559 cache_recalc_neg_min(ncnegminpct); 2560 cache_unlock_all_buckets(); 2561 cache_unlock_all_vnodes(); 2562 ncfreetbl(old_nchashtbl); 2563 } 2564 2565 /* 2566 * Invalidate all entries from and to a particular vnode. 2567 */ 2568 static void 2569 cache_purge_impl(struct vnode *vp) 2570 { 2571 struct cache_freebatch batch; 2572 struct namecache *ncp; 2573 struct mtx *vlp, *vlp2; 2574 2575 TAILQ_INIT(&batch); 2576 vlp = VP2VNODELOCK(vp); 2577 vlp2 = NULL; 2578 mtx_lock(vlp); 2579 retry: 2580 while (!LIST_EMPTY(&vp->v_cache_src)) { 2581 ncp = LIST_FIRST(&vp->v_cache_src); 2582 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 2583 goto retry; 2584 TAILQ_INSERT_TAIL(&batch, ncp, nc_dst); 2585 } 2586 while (!TAILQ_EMPTY(&vp->v_cache_dst)) { 2587 ncp = TAILQ_FIRST(&vp->v_cache_dst); 2588 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 2589 goto retry; 2590 TAILQ_INSERT_TAIL(&batch, ncp, nc_dst); 2591 } 2592 ncp = vp->v_cache_dd; 2593 if (ncp != NULL) { 2594 KASSERT(ncp->nc_flag & NCF_ISDOTDOT, 2595 ("lost dotdot link")); 2596 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 2597 goto retry; 2598 TAILQ_INSERT_TAIL(&batch, ncp, nc_dst); 2599 } 2600 KASSERT(vp->v_cache_dd == NULL, ("incomplete purge")); 2601 mtx_unlock(vlp); 2602 if (vlp2 != NULL) 2603 mtx_unlock(vlp2); 2604 cache_free_batch(&batch); 2605 } 2606 2607 /* 2608 * Opportunistic check to see if there is anything to do. 2609 */ 2610 static bool 2611 cache_has_entries(struct vnode *vp) 2612 { 2613 2614 if (LIST_EMPTY(&vp->v_cache_src) && TAILQ_EMPTY(&vp->v_cache_dst) && 2615 vp->v_cache_dd == NULL) 2616 return (false); 2617 return (true); 2618 } 2619 2620 void 2621 cache_purge(struct vnode *vp) 2622 { 2623 2624 SDT_PROBE1(vfs, namecache, purge, done, vp); 2625 if (!cache_has_entries(vp)) 2626 return; 2627 cache_purge_impl(vp); 2628 } 2629 2630 /* 2631 * Only to be used by vgone. 2632 */ 2633 void 2634 cache_purge_vgone(struct vnode *vp) 2635 { 2636 struct mtx *vlp; 2637 2638 VNPASS(VN_IS_DOOMED(vp), vp); 2639 if (cache_has_entries(vp)) { 2640 cache_purge_impl(vp); 2641 return; 2642 } 2643 2644 /* 2645 * Serialize against a potential thread doing cache_purge. 2646 */ 2647 vlp = VP2VNODELOCK(vp); 2648 mtx_wait_unlocked(vlp); 2649 if (cache_has_entries(vp)) { 2650 cache_purge_impl(vp); 2651 return; 2652 } 2653 return; 2654 } 2655 2656 /* 2657 * Invalidate all negative entries for a particular directory vnode. 2658 */ 2659 void 2660 cache_purge_negative(struct vnode *vp) 2661 { 2662 struct cache_freebatch batch; 2663 struct namecache *ncp, *nnp; 2664 struct mtx *vlp; 2665 2666 SDT_PROBE1(vfs, namecache, purge_negative, done, vp); 2667 if (LIST_EMPTY(&vp->v_cache_src)) 2668 return; 2669 TAILQ_INIT(&batch); 2670 vlp = VP2VNODELOCK(vp); 2671 mtx_lock(vlp); 2672 LIST_FOREACH_SAFE(ncp, &vp->v_cache_src, nc_src, nnp) { 2673 if (!(ncp->nc_flag & NCF_NEGATIVE)) 2674 continue; 2675 cache_zap_negative_locked_vnode_kl(ncp, vp); 2676 TAILQ_INSERT_TAIL(&batch, ncp, nc_dst); 2677 } 2678 mtx_unlock(vlp); 2679 cache_free_batch(&batch); 2680 } 2681 2682 /* 2683 * Entry points for modifying VOP operations. 2684 */ 2685 void 2686 cache_vop_rename(struct vnode *fdvp, struct vnode *fvp, struct vnode *tdvp, 2687 struct vnode *tvp, struct componentname *fcnp, struct componentname *tcnp) 2688 { 2689 2690 ASSERT_VOP_IN_SEQC(fdvp); 2691 ASSERT_VOP_IN_SEQC(fvp); 2692 ASSERT_VOP_IN_SEQC(tdvp); 2693 if (tvp != NULL) 2694 ASSERT_VOP_IN_SEQC(tvp); 2695 2696 cache_purge(fvp); 2697 if (tvp != NULL) { 2698 cache_purge(tvp); 2699 KASSERT(!cache_remove_cnp(tdvp, tcnp), 2700 ("%s: lingering negative entry", __func__)); 2701 } else { 2702 cache_remove_cnp(tdvp, tcnp); 2703 } 2704 } 2705 2706 void 2707 cache_vop_rmdir(struct vnode *dvp, struct vnode *vp) 2708 { 2709 2710 ASSERT_VOP_IN_SEQC(dvp); 2711 ASSERT_VOP_IN_SEQC(vp); 2712 cache_purge(vp); 2713 } 2714 2715 #ifdef INVARIANTS 2716 /* 2717 * Validate that if an entry exists it matches. 2718 */ 2719 void 2720 cache_validate(struct vnode *dvp, struct vnode *vp, struct componentname *cnp) 2721 { 2722 struct namecache *ncp; 2723 struct mtx *blp; 2724 uint32_t hash; 2725 2726 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp); 2727 if (CK_SLIST_EMPTY(NCHHASH(hash))) 2728 return; 2729 blp = HASH2BUCKETLOCK(hash); 2730 mtx_lock(blp); 2731 CK_SLIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 2732 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 2733 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) { 2734 if (ncp->nc_vp != vp) 2735 panic("%s: mismatch (%p != %p); ncp %p [%s] dvp %p vp %p\n", 2736 __func__, vp, ncp->nc_vp, ncp, ncp->nc_name, ncp->nc_dvp, 2737 ncp->nc_vp); 2738 } 2739 } 2740 mtx_unlock(blp); 2741 } 2742 #endif 2743 2744 /* 2745 * Flush all entries referencing a particular filesystem. 2746 */ 2747 void 2748 cache_purgevfs(struct mount *mp) 2749 { 2750 struct vnode *vp, *mvp; 2751 2752 SDT_PROBE1(vfs, namecache, purgevfs, done, mp); 2753 /* 2754 * Somewhat wasteful iteration over all vnodes. Would be better to 2755 * support filtering and avoid the interlock to begin with. 2756 */ 2757 MNT_VNODE_FOREACH_ALL(vp, mp, mvp) { 2758 if (!cache_has_entries(vp)) { 2759 VI_UNLOCK(vp); 2760 continue; 2761 } 2762 vholdl(vp); 2763 VI_UNLOCK(vp); 2764 cache_purge(vp); 2765 vdrop(vp); 2766 } 2767 } 2768 2769 /* 2770 * Perform canonical checks and cache lookup and pass on to filesystem 2771 * through the vop_cachedlookup only if needed. 2772 */ 2773 2774 int 2775 vfs_cache_lookup(struct vop_lookup_args *ap) 2776 { 2777 struct vnode *dvp; 2778 int error; 2779 struct vnode **vpp = ap->a_vpp; 2780 struct componentname *cnp = ap->a_cnp; 2781 int flags = cnp->cn_flags; 2782 2783 *vpp = NULL; 2784 dvp = ap->a_dvp; 2785 2786 if (dvp->v_type != VDIR) 2787 return (ENOTDIR); 2788 2789 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && 2790 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 2791 return (EROFS); 2792 2793 error = vn_dir_check_exec(dvp, cnp); 2794 if (error != 0) 2795 return (error); 2796 2797 error = cache_lookup(dvp, vpp, cnp, NULL, NULL); 2798 if (error == 0) 2799 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); 2800 if (error == -1) 2801 return (0); 2802 return (error); 2803 } 2804 2805 /* Implementation of the getcwd syscall. */ 2806 int 2807 sys___getcwd(struct thread *td, struct __getcwd_args *uap) 2808 { 2809 char *buf, *retbuf; 2810 size_t buflen; 2811 int error; 2812 2813 buflen = uap->buflen; 2814 if (__predict_false(buflen < 2)) 2815 return (EINVAL); 2816 if (buflen > MAXPATHLEN) 2817 buflen = MAXPATHLEN; 2818 2819 buf = uma_zalloc(namei_zone, M_WAITOK); 2820 error = vn_getcwd(buf, &retbuf, &buflen); 2821 if (error == 0) 2822 error = copyout(retbuf, uap->buf, buflen); 2823 uma_zfree(namei_zone, buf); 2824 return (error); 2825 } 2826 2827 int 2828 vn_getcwd(char *buf, char **retbuf, size_t *buflen) 2829 { 2830 struct pwd *pwd; 2831 int error; 2832 2833 vfs_smr_enter(); 2834 pwd = pwd_get_smr(); 2835 error = vn_fullpath_any_smr(pwd->pwd_cdir, pwd->pwd_rdir, buf, retbuf, 2836 buflen, 0); 2837 VFS_SMR_ASSERT_NOT_ENTERED(); 2838 if (error < 0) { 2839 pwd = pwd_hold(curthread); 2840 error = vn_fullpath_any(pwd->pwd_cdir, pwd->pwd_rdir, buf, 2841 retbuf, buflen); 2842 pwd_drop(pwd); 2843 } 2844 2845 #ifdef KTRACE 2846 if (KTRPOINT(curthread, KTR_NAMEI) && error == 0) 2847 ktrnamei(*retbuf); 2848 #endif 2849 return (error); 2850 } 2851 2852 static int 2853 kern___realpathat(struct thread *td, int fd, const char *path, char *buf, 2854 size_t size, int flags, enum uio_seg pathseg) 2855 { 2856 struct nameidata nd; 2857 char *retbuf, *freebuf; 2858 int error; 2859 2860 if (flags != 0) 2861 return (EINVAL); 2862 NDINIT_ATRIGHTS(&nd, LOOKUP, FOLLOW | SAVENAME | WANTPARENT | AUDITVNODE1, 2863 pathseg, path, fd, &cap_fstat_rights, td); 2864 if ((error = namei(&nd)) != 0) 2865 return (error); 2866 error = vn_fullpath_hardlink(&nd, &retbuf, &freebuf, &size); 2867 if (error == 0) { 2868 error = copyout(retbuf, buf, size); 2869 free(freebuf, M_TEMP); 2870 } 2871 NDFREE(&nd, 0); 2872 return (error); 2873 } 2874 2875 int 2876 sys___realpathat(struct thread *td, struct __realpathat_args *uap) 2877 { 2878 2879 return (kern___realpathat(td, uap->fd, uap->path, uap->buf, uap->size, 2880 uap->flags, UIO_USERSPACE)); 2881 } 2882 2883 /* 2884 * Retrieve the full filesystem path that correspond to a vnode from the name 2885 * cache (if available) 2886 */ 2887 int 2888 vn_fullpath(struct vnode *vp, char **retbuf, char **freebuf) 2889 { 2890 struct pwd *pwd; 2891 char *buf; 2892 size_t buflen; 2893 int error; 2894 2895 if (__predict_false(vp == NULL)) 2896 return (EINVAL); 2897 2898 buflen = MAXPATHLEN; 2899 buf = malloc(buflen, M_TEMP, M_WAITOK); 2900 vfs_smr_enter(); 2901 pwd = pwd_get_smr(); 2902 error = vn_fullpath_any_smr(vp, pwd->pwd_rdir, buf, retbuf, &buflen, 0); 2903 VFS_SMR_ASSERT_NOT_ENTERED(); 2904 if (error < 0) { 2905 pwd = pwd_hold(curthread); 2906 error = vn_fullpath_any(vp, pwd->pwd_rdir, buf, retbuf, &buflen); 2907 pwd_drop(pwd); 2908 } 2909 if (error == 0) 2910 *freebuf = buf; 2911 else 2912 free(buf, M_TEMP); 2913 return (error); 2914 } 2915 2916 /* 2917 * This function is similar to vn_fullpath, but it attempts to lookup the 2918 * pathname relative to the global root mount point. This is required for the 2919 * auditing sub-system, as audited pathnames must be absolute, relative to the 2920 * global root mount point. 2921 */ 2922 int 2923 vn_fullpath_global(struct vnode *vp, char **retbuf, char **freebuf) 2924 { 2925 char *buf; 2926 size_t buflen; 2927 int error; 2928 2929 if (__predict_false(vp == NULL)) 2930 return (EINVAL); 2931 buflen = MAXPATHLEN; 2932 buf = malloc(buflen, M_TEMP, M_WAITOK); 2933 vfs_smr_enter(); 2934 error = vn_fullpath_any_smr(vp, rootvnode, buf, retbuf, &buflen, 0); 2935 VFS_SMR_ASSERT_NOT_ENTERED(); 2936 if (error < 0) { 2937 error = vn_fullpath_any(vp, rootvnode, buf, retbuf, &buflen); 2938 } 2939 if (error == 0) 2940 *freebuf = buf; 2941 else 2942 free(buf, M_TEMP); 2943 return (error); 2944 } 2945 2946 static struct namecache * 2947 vn_dd_from_dst(struct vnode *vp) 2948 { 2949 struct namecache *ncp; 2950 2951 cache_assert_vnode_locked(vp); 2952 TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst) { 2953 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 2954 return (ncp); 2955 } 2956 return (NULL); 2957 } 2958 2959 int 2960 vn_vptocnp(struct vnode **vp, char *buf, size_t *buflen) 2961 { 2962 struct vnode *dvp; 2963 struct namecache *ncp; 2964 struct mtx *vlp; 2965 int error; 2966 2967 vlp = VP2VNODELOCK(*vp); 2968 mtx_lock(vlp); 2969 ncp = (*vp)->v_cache_dd; 2970 if (ncp != NULL && (ncp->nc_flag & NCF_ISDOTDOT) == 0) { 2971 KASSERT(ncp == vn_dd_from_dst(*vp), 2972 ("%s: mismatch for dd entry (%p != %p)", __func__, 2973 ncp, vn_dd_from_dst(*vp))); 2974 } else { 2975 ncp = vn_dd_from_dst(*vp); 2976 } 2977 if (ncp != NULL) { 2978 if (*buflen < ncp->nc_nlen) { 2979 mtx_unlock(vlp); 2980 vrele(*vp); 2981 counter_u64_add(numfullpathfail4, 1); 2982 error = ENOMEM; 2983 SDT_PROBE3(vfs, namecache, fullpath, return, error, 2984 vp, NULL); 2985 return (error); 2986 } 2987 *buflen -= ncp->nc_nlen; 2988 memcpy(buf + *buflen, ncp->nc_name, ncp->nc_nlen); 2989 SDT_PROBE3(vfs, namecache, fullpath, hit, ncp->nc_dvp, 2990 ncp->nc_name, vp); 2991 dvp = *vp; 2992 *vp = ncp->nc_dvp; 2993 vref(*vp); 2994 mtx_unlock(vlp); 2995 vrele(dvp); 2996 return (0); 2997 } 2998 SDT_PROBE1(vfs, namecache, fullpath, miss, vp); 2999 3000 mtx_unlock(vlp); 3001 vn_lock(*vp, LK_SHARED | LK_RETRY); 3002 error = VOP_VPTOCNP(*vp, &dvp, buf, buflen); 3003 vput(*vp); 3004 if (error) { 3005 counter_u64_add(numfullpathfail2, 1); 3006 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); 3007 return (error); 3008 } 3009 3010 *vp = dvp; 3011 if (VN_IS_DOOMED(dvp)) { 3012 /* forced unmount */ 3013 vrele(dvp); 3014 error = ENOENT; 3015 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); 3016 return (error); 3017 } 3018 /* 3019 * *vp has its use count incremented still. 3020 */ 3021 3022 return (0); 3023 } 3024 3025 /* 3026 * Resolve a directory to a pathname. 3027 * 3028 * The name of the directory can always be found in the namecache or fetched 3029 * from the filesystem. There is also guaranteed to be only one parent, meaning 3030 * we can just follow vnodes up until we find the root. 3031 * 3032 * The vnode must be referenced. 3033 */ 3034 static int 3035 vn_fullpath_dir(struct vnode *vp, struct vnode *rdir, char *buf, char **retbuf, 3036 size_t *len, size_t addend) 3037 { 3038 #ifdef KDTRACE_HOOKS 3039 struct vnode *startvp = vp; 3040 #endif 3041 struct vnode *vp1; 3042 size_t buflen; 3043 int error; 3044 bool slash_prefixed; 3045 3046 VNPASS(vp->v_type == VDIR || VN_IS_DOOMED(vp), vp); 3047 VNPASS(vp->v_usecount > 0, vp); 3048 3049 buflen = *len; 3050 3051 slash_prefixed = true; 3052 if (addend == 0) { 3053 MPASS(*len >= 2); 3054 buflen--; 3055 buf[buflen] = '\0'; 3056 slash_prefixed = false; 3057 } 3058 3059 error = 0; 3060 3061 SDT_PROBE1(vfs, namecache, fullpath, entry, vp); 3062 counter_u64_add(numfullpathcalls, 1); 3063 while (vp != rdir && vp != rootvnode) { 3064 /* 3065 * The vp vnode must be already fully constructed, 3066 * since it is either found in namecache or obtained 3067 * from VOP_VPTOCNP(). We may test for VV_ROOT safely 3068 * without obtaining the vnode lock. 3069 */ 3070 if ((vp->v_vflag & VV_ROOT) != 0) { 3071 vn_lock(vp, LK_RETRY | LK_SHARED); 3072 3073 /* 3074 * With the vnode locked, check for races with 3075 * unmount, forced or not. Note that we 3076 * already verified that vp is not equal to 3077 * the root vnode, which means that 3078 * mnt_vnodecovered can be NULL only for the 3079 * case of unmount. 3080 */ 3081 if (VN_IS_DOOMED(vp) || 3082 (vp1 = vp->v_mount->mnt_vnodecovered) == NULL || 3083 vp1->v_mountedhere != vp->v_mount) { 3084 vput(vp); 3085 error = ENOENT; 3086 SDT_PROBE3(vfs, namecache, fullpath, return, 3087 error, vp, NULL); 3088 break; 3089 } 3090 3091 vref(vp1); 3092 vput(vp); 3093 vp = vp1; 3094 continue; 3095 } 3096 if (vp->v_type != VDIR) { 3097 vrele(vp); 3098 counter_u64_add(numfullpathfail1, 1); 3099 error = ENOTDIR; 3100 SDT_PROBE3(vfs, namecache, fullpath, return, 3101 error, vp, NULL); 3102 break; 3103 } 3104 error = vn_vptocnp(&vp, buf, &buflen); 3105 if (error) 3106 break; 3107 if (buflen == 0) { 3108 vrele(vp); 3109 error = ENOMEM; 3110 SDT_PROBE3(vfs, namecache, fullpath, return, error, 3111 startvp, NULL); 3112 break; 3113 } 3114 buf[--buflen] = '/'; 3115 slash_prefixed = true; 3116 } 3117 if (error) 3118 return (error); 3119 if (!slash_prefixed) { 3120 if (buflen == 0) { 3121 vrele(vp); 3122 counter_u64_add(numfullpathfail4, 1); 3123 SDT_PROBE3(vfs, namecache, fullpath, return, ENOMEM, 3124 startvp, NULL); 3125 return (ENOMEM); 3126 } 3127 buf[--buflen] = '/'; 3128 } 3129 counter_u64_add(numfullpathfound, 1); 3130 vrele(vp); 3131 3132 *retbuf = buf + buflen; 3133 SDT_PROBE3(vfs, namecache, fullpath, return, 0, startvp, *retbuf); 3134 *len -= buflen; 3135 *len += addend; 3136 return (0); 3137 } 3138 3139 /* 3140 * Resolve an arbitrary vnode to a pathname. 3141 * 3142 * Note 2 caveats: 3143 * - hardlinks are not tracked, thus if the vnode is not a directory this can 3144 * resolve to a different path than the one used to find it 3145 * - namecache is not mandatory, meaning names are not guaranteed to be added 3146 * (in which case resolving fails) 3147 */ 3148 static void __inline 3149 cache_rev_failed_impl(int *reason, int line) 3150 { 3151 3152 *reason = line; 3153 } 3154 #define cache_rev_failed(var) cache_rev_failed_impl((var), __LINE__) 3155 3156 static int 3157 vn_fullpath_any_smr(struct vnode *vp, struct vnode *rdir, char *buf, 3158 char **retbuf, size_t *buflen, size_t addend) 3159 { 3160 #ifdef KDTRACE_HOOKS 3161 struct vnode *startvp = vp; 3162 #endif 3163 struct vnode *tvp; 3164 struct mount *mp; 3165 struct namecache *ncp; 3166 size_t orig_buflen; 3167 int reason; 3168 int error; 3169 #ifdef KDTRACE_HOOKS 3170 int i; 3171 #endif 3172 seqc_t vp_seqc, tvp_seqc; 3173 u_char nc_flag; 3174 3175 VFS_SMR_ASSERT_ENTERED(); 3176 3177 if (!cache_fast_revlookup) { 3178 vfs_smr_exit(); 3179 return (-1); 3180 } 3181 3182 orig_buflen = *buflen; 3183 3184 if (addend == 0) { 3185 MPASS(*buflen >= 2); 3186 *buflen -= 1; 3187 buf[*buflen] = '\0'; 3188 } 3189 3190 if (vp == rdir || vp == rootvnode) { 3191 if (addend == 0) { 3192 *buflen -= 1; 3193 buf[*buflen] = '/'; 3194 } 3195 goto out_ok; 3196 } 3197 3198 #ifdef KDTRACE_HOOKS 3199 i = 0; 3200 #endif 3201 error = -1; 3202 ncp = NULL; /* for sdt probe down below */ 3203 vp_seqc = vn_seqc_read_any(vp); 3204 if (seqc_in_modify(vp_seqc)) { 3205 cache_rev_failed(&reason); 3206 goto out_abort; 3207 } 3208 3209 for (;;) { 3210 #ifdef KDTRACE_HOOKS 3211 i++; 3212 #endif 3213 if ((vp->v_vflag & VV_ROOT) != 0) { 3214 mp = atomic_load_ptr(&vp->v_mount); 3215 if (mp == NULL) { 3216 cache_rev_failed(&reason); 3217 goto out_abort; 3218 } 3219 tvp = atomic_load_ptr(&mp->mnt_vnodecovered); 3220 tvp_seqc = vn_seqc_read_any(tvp); 3221 if (seqc_in_modify(tvp_seqc)) { 3222 cache_rev_failed(&reason); 3223 goto out_abort; 3224 } 3225 if (!vn_seqc_consistent(vp, vp_seqc)) { 3226 cache_rev_failed(&reason); 3227 goto out_abort; 3228 } 3229 vp = tvp; 3230 vp_seqc = tvp_seqc; 3231 continue; 3232 } 3233 ncp = atomic_load_ptr(&vp->v_cache_dd); 3234 if (ncp == NULL) { 3235 cache_rev_failed(&reason); 3236 goto out_abort; 3237 } 3238 nc_flag = atomic_load_char(&ncp->nc_flag); 3239 if ((nc_flag & NCF_ISDOTDOT) != 0) { 3240 cache_rev_failed(&reason); 3241 goto out_abort; 3242 } 3243 if (!cache_ncp_canuse(ncp)) { 3244 cache_rev_failed(&reason); 3245 goto out_abort; 3246 } 3247 if (ncp->nc_nlen >= *buflen) { 3248 cache_rev_failed(&reason); 3249 error = ENOMEM; 3250 goto out_abort; 3251 } 3252 *buflen -= ncp->nc_nlen; 3253 memcpy(buf + *buflen, ncp->nc_name, ncp->nc_nlen); 3254 *buflen -= 1; 3255 buf[*buflen] = '/'; 3256 tvp = ncp->nc_dvp; 3257 tvp_seqc = vn_seqc_read_any(tvp); 3258 if (seqc_in_modify(tvp_seqc)) { 3259 cache_rev_failed(&reason); 3260 goto out_abort; 3261 } 3262 if (!vn_seqc_consistent(vp, vp_seqc)) { 3263 cache_rev_failed(&reason); 3264 goto out_abort; 3265 } 3266 vp = tvp; 3267 vp_seqc = tvp_seqc; 3268 if (vp == rdir || vp == rootvnode) 3269 break; 3270 } 3271 out_ok: 3272 vfs_smr_exit(); 3273 *retbuf = buf + *buflen; 3274 *buflen = orig_buflen - *buflen + addend; 3275 SDT_PROBE2(vfs, namecache, fullpath_smr, hit, startvp, *retbuf); 3276 return (0); 3277 3278 out_abort: 3279 *buflen = orig_buflen; 3280 SDT_PROBE4(vfs, namecache, fullpath_smr, miss, startvp, ncp, reason, i); 3281 vfs_smr_exit(); 3282 return (error); 3283 } 3284 3285 static int 3286 vn_fullpath_any(struct vnode *vp, struct vnode *rdir, char *buf, char **retbuf, 3287 size_t *buflen) 3288 { 3289 size_t orig_buflen, addend; 3290 int error; 3291 3292 if (*buflen < 2) 3293 return (EINVAL); 3294 3295 orig_buflen = *buflen; 3296 3297 vref(vp); 3298 addend = 0; 3299 if (vp->v_type != VDIR) { 3300 *buflen -= 1; 3301 buf[*buflen] = '\0'; 3302 error = vn_vptocnp(&vp, buf, buflen); 3303 if (error) 3304 return (error); 3305 if (*buflen == 0) { 3306 vrele(vp); 3307 return (ENOMEM); 3308 } 3309 *buflen -= 1; 3310 buf[*buflen] = '/'; 3311 addend = orig_buflen - *buflen; 3312 } 3313 3314 return (vn_fullpath_dir(vp, rdir, buf, retbuf, buflen, addend)); 3315 } 3316 3317 /* 3318 * Resolve an arbitrary vnode to a pathname (taking care of hardlinks). 3319 * 3320 * Since the namecache does not track hardlinks, the caller is expected to first 3321 * look up the target vnode with SAVENAME | WANTPARENT flags passed to namei. 3322 * 3323 * Then we have 2 cases: 3324 * - if the found vnode is a directory, the path can be constructed just by 3325 * following names up the chain 3326 * - otherwise we populate the buffer with the saved name and start resolving 3327 * from the parent 3328 */ 3329 static int 3330 vn_fullpath_hardlink(struct nameidata *ndp, char **retbuf, char **freebuf, 3331 size_t *buflen) 3332 { 3333 char *buf, *tmpbuf; 3334 struct pwd *pwd; 3335 struct componentname *cnp; 3336 struct vnode *vp; 3337 size_t addend; 3338 int error; 3339 enum vtype type; 3340 3341 if (*buflen < 2) 3342 return (EINVAL); 3343 if (*buflen > MAXPATHLEN) 3344 *buflen = MAXPATHLEN; 3345 3346 buf = malloc(*buflen, M_TEMP, M_WAITOK); 3347 3348 addend = 0; 3349 vp = ndp->ni_vp; 3350 /* 3351 * Check for VBAD to work around the vp_crossmp bug in lookup(). 3352 * 3353 * For example consider tmpfs on /tmp and realpath /tmp. ni_vp will be 3354 * set to mount point's root vnode while ni_dvp will be vp_crossmp. 3355 * If the type is VDIR (like in this very case) we can skip looking 3356 * at ni_dvp in the first place. However, since vnodes get passed here 3357 * unlocked the target may transition to doomed state (type == VBAD) 3358 * before we get to evaluate the condition. If this happens, we will 3359 * populate part of the buffer and descend to vn_fullpath_dir with 3360 * vp == vp_crossmp. Prevent the problem by checking for VBAD. 3361 * 3362 * This should be atomic_load(&vp->v_type) but it is illegal to take 3363 * an address of a bit field, even if said field is sized to char. 3364 * Work around the problem by reading the value into a full-sized enum 3365 * and then re-reading it with atomic_load which will still prevent 3366 * the compiler from re-reading down the road. 3367 */ 3368 type = vp->v_type; 3369 type = atomic_load_int(&type); 3370 if (type == VBAD) { 3371 error = ENOENT; 3372 goto out_bad; 3373 } 3374 if (type != VDIR) { 3375 cnp = &ndp->ni_cnd; 3376 addend = cnp->cn_namelen + 2; 3377 if (*buflen < addend) { 3378 error = ENOMEM; 3379 goto out_bad; 3380 } 3381 *buflen -= addend; 3382 tmpbuf = buf + *buflen; 3383 tmpbuf[0] = '/'; 3384 memcpy(&tmpbuf[1], cnp->cn_nameptr, cnp->cn_namelen); 3385 tmpbuf[addend - 1] = '\0'; 3386 vp = ndp->ni_dvp; 3387 } 3388 3389 vfs_smr_enter(); 3390 pwd = pwd_get_smr(); 3391 error = vn_fullpath_any_smr(vp, pwd->pwd_rdir, buf, retbuf, buflen, 3392 addend); 3393 VFS_SMR_ASSERT_NOT_ENTERED(); 3394 if (error < 0) { 3395 pwd = pwd_hold(curthread); 3396 vref(vp); 3397 error = vn_fullpath_dir(vp, pwd->pwd_rdir, buf, retbuf, buflen, 3398 addend); 3399 pwd_drop(pwd); 3400 if (error != 0) 3401 goto out_bad; 3402 } 3403 3404 *freebuf = buf; 3405 3406 return (0); 3407 out_bad: 3408 free(buf, M_TEMP); 3409 return (error); 3410 } 3411 3412 struct vnode * 3413 vn_dir_dd_ino(struct vnode *vp) 3414 { 3415 struct namecache *ncp; 3416 struct vnode *ddvp; 3417 struct mtx *vlp; 3418 enum vgetstate vs; 3419 3420 ASSERT_VOP_LOCKED(vp, "vn_dir_dd_ino"); 3421 vlp = VP2VNODELOCK(vp); 3422 mtx_lock(vlp); 3423 TAILQ_FOREACH(ncp, &(vp->v_cache_dst), nc_dst) { 3424 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) 3425 continue; 3426 ddvp = ncp->nc_dvp; 3427 vs = vget_prep(ddvp); 3428 mtx_unlock(vlp); 3429 if (vget_finish(ddvp, LK_SHARED | LK_NOWAIT, vs)) 3430 return (NULL); 3431 return (ddvp); 3432 } 3433 mtx_unlock(vlp); 3434 return (NULL); 3435 } 3436 3437 int 3438 vn_commname(struct vnode *vp, char *buf, u_int buflen) 3439 { 3440 struct namecache *ncp; 3441 struct mtx *vlp; 3442 int l; 3443 3444 vlp = VP2VNODELOCK(vp); 3445 mtx_lock(vlp); 3446 TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst) 3447 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 3448 break; 3449 if (ncp == NULL) { 3450 mtx_unlock(vlp); 3451 return (ENOENT); 3452 } 3453 l = min(ncp->nc_nlen, buflen - 1); 3454 memcpy(buf, ncp->nc_name, l); 3455 mtx_unlock(vlp); 3456 buf[l] = '\0'; 3457 return (0); 3458 } 3459 3460 /* 3461 * This function updates path string to vnode's full global path 3462 * and checks the size of the new path string against the pathlen argument. 3463 * 3464 * Requires a locked, referenced vnode. 3465 * Vnode is re-locked on success or ENODEV, otherwise unlocked. 3466 * 3467 * If vp is a directory, the call to vn_fullpath_global() always succeeds 3468 * because it falls back to the ".." lookup if the namecache lookup fails. 3469 */ 3470 int 3471 vn_path_to_global_path(struct thread *td, struct vnode *vp, char *path, 3472 u_int pathlen) 3473 { 3474 struct nameidata nd; 3475 struct vnode *vp1; 3476 char *rpath, *fbuf; 3477 int error; 3478 3479 ASSERT_VOP_ELOCKED(vp, __func__); 3480 3481 /* Construct global filesystem path from vp. */ 3482 VOP_UNLOCK(vp); 3483 error = vn_fullpath_global(vp, &rpath, &fbuf); 3484 3485 if (error != 0) { 3486 vrele(vp); 3487 return (error); 3488 } 3489 3490 if (strlen(rpath) >= pathlen) { 3491 vrele(vp); 3492 error = ENAMETOOLONG; 3493 goto out; 3494 } 3495 3496 /* 3497 * Re-lookup the vnode by path to detect a possible rename. 3498 * As a side effect, the vnode is relocked. 3499 * If vnode was renamed, return ENOENT. 3500 */ 3501 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1, 3502 UIO_SYSSPACE, path, td); 3503 error = namei(&nd); 3504 if (error != 0) { 3505 vrele(vp); 3506 goto out; 3507 } 3508 NDFREE(&nd, NDF_ONLY_PNBUF); 3509 vp1 = nd.ni_vp; 3510 vrele(vp); 3511 if (vp1 == vp) 3512 strcpy(path, rpath); 3513 else { 3514 vput(vp1); 3515 error = ENOENT; 3516 } 3517 3518 out: 3519 free(fbuf, M_TEMP); 3520 return (error); 3521 } 3522 3523 #ifdef DDB 3524 static void 3525 db_print_vpath(struct vnode *vp) 3526 { 3527 3528 while (vp != NULL) { 3529 db_printf("%p: ", vp); 3530 if (vp == rootvnode) { 3531 db_printf("/"); 3532 vp = NULL; 3533 } else { 3534 if (vp->v_vflag & VV_ROOT) { 3535 db_printf("<mount point>"); 3536 vp = vp->v_mount->mnt_vnodecovered; 3537 } else { 3538 struct namecache *ncp; 3539 char *ncn; 3540 int i; 3541 3542 ncp = TAILQ_FIRST(&vp->v_cache_dst); 3543 if (ncp != NULL) { 3544 ncn = ncp->nc_name; 3545 for (i = 0; i < ncp->nc_nlen; i++) 3546 db_printf("%c", *ncn++); 3547 vp = ncp->nc_dvp; 3548 } else { 3549 vp = NULL; 3550 } 3551 } 3552 } 3553 db_printf("\n"); 3554 } 3555 3556 return; 3557 } 3558 3559 DB_SHOW_COMMAND(vpath, db_show_vpath) 3560 { 3561 struct vnode *vp; 3562 3563 if (!have_addr) { 3564 db_printf("usage: show vpath <struct vnode *>\n"); 3565 return; 3566 } 3567 3568 vp = (struct vnode *)addr; 3569 db_print_vpath(vp); 3570 } 3571 3572 #endif 3573 3574 static bool __read_frequently cache_fast_lookup = true; 3575 SYSCTL_BOOL(_vfs, OID_AUTO, cache_fast_lookup, CTLFLAG_RW, 3576 &cache_fast_lookup, 0, ""); 3577 3578 #define CACHE_FPL_FAILED -2020 3579 3580 /* 3581 * Components of nameidata (or objects it can point to) which may 3582 * need restoring in case fast path lookup fails. 3583 */ 3584 struct nameidata_saved { 3585 char *cn_nameptr; 3586 size_t ni_pathlen; 3587 int cn_flags; 3588 }; 3589 3590 struct cache_fpl { 3591 struct nameidata *ndp; 3592 struct componentname *cnp; 3593 struct pwd *pwd; 3594 struct vnode *dvp; 3595 struct vnode *tvp; 3596 seqc_t dvp_seqc; 3597 seqc_t tvp_seqc; 3598 struct nameidata_saved snd; 3599 int line; 3600 enum cache_fpl_status status:8; 3601 bool in_smr; 3602 bool fsearch; 3603 }; 3604 3605 static void 3606 cache_fpl_cleanup_cnp(struct componentname *cnp) 3607 { 3608 3609 uma_zfree(namei_zone, cnp->cn_pnbuf); 3610 #ifdef DIAGNOSTIC 3611 cnp->cn_pnbuf = NULL; 3612 cnp->cn_nameptr = NULL; 3613 #endif 3614 } 3615 3616 static struct vnode * 3617 cache_fpl_handle_root(struct cache_fpl *fpl) 3618 { 3619 struct nameidata *ndp; 3620 struct componentname *cnp; 3621 3622 ndp = fpl->ndp; 3623 cnp = fpl->cnp; 3624 3625 MPASS(*(cnp->cn_nameptr) == '/'); 3626 cnp->cn_nameptr++; 3627 ndp->ni_pathlen--; 3628 3629 if (__predict_false(*(cnp->cn_nameptr) == '/')) { 3630 do { 3631 cnp->cn_nameptr++; 3632 ndp->ni_pathlen--; 3633 } while (*(cnp->cn_nameptr) == '/'); 3634 } 3635 3636 return (ndp->ni_rootdir); 3637 } 3638 3639 static void 3640 cache_fpl_checkpoint(struct cache_fpl *fpl, struct nameidata_saved *snd) 3641 { 3642 3643 snd->cn_flags = fpl->ndp->ni_cnd.cn_flags; 3644 snd->cn_nameptr = fpl->ndp->ni_cnd.cn_nameptr; 3645 snd->ni_pathlen = fpl->ndp->ni_pathlen; 3646 } 3647 3648 static void 3649 cache_fpl_restore_partial(struct cache_fpl *fpl, struct nameidata_saved *snd) 3650 { 3651 3652 fpl->ndp->ni_cnd.cn_flags = snd->cn_flags; 3653 fpl->ndp->ni_cnd.cn_nameptr = snd->cn_nameptr; 3654 fpl->ndp->ni_pathlen = snd->ni_pathlen; 3655 } 3656 3657 static void 3658 cache_fpl_restore_abort(struct cache_fpl *fpl, struct nameidata_saved *snd) 3659 { 3660 3661 cache_fpl_restore_partial(fpl, snd); 3662 /* 3663 * It is 0 on entry by API contract. 3664 */ 3665 fpl->ndp->ni_resflags = 0; 3666 } 3667 3668 #ifdef INVARIANTS 3669 #define cache_fpl_smr_assert_entered(fpl) ({ \ 3670 struct cache_fpl *_fpl = (fpl); \ 3671 MPASS(_fpl->in_smr == true); \ 3672 VFS_SMR_ASSERT_ENTERED(); \ 3673 }) 3674 #define cache_fpl_smr_assert_not_entered(fpl) ({ \ 3675 struct cache_fpl *_fpl = (fpl); \ 3676 MPASS(_fpl->in_smr == false); \ 3677 VFS_SMR_ASSERT_NOT_ENTERED(); \ 3678 }) 3679 #else 3680 #define cache_fpl_smr_assert_entered(fpl) do { } while (0) 3681 #define cache_fpl_smr_assert_not_entered(fpl) do { } while (0) 3682 #endif 3683 3684 #define cache_fpl_smr_enter_initial(fpl) ({ \ 3685 struct cache_fpl *_fpl = (fpl); \ 3686 vfs_smr_enter(); \ 3687 _fpl->in_smr = true; \ 3688 }) 3689 3690 #define cache_fpl_smr_enter(fpl) ({ \ 3691 struct cache_fpl *_fpl = (fpl); \ 3692 MPASS(_fpl->in_smr == false); \ 3693 vfs_smr_enter(); \ 3694 _fpl->in_smr = true; \ 3695 }) 3696 3697 #define cache_fpl_smr_exit(fpl) ({ \ 3698 struct cache_fpl *_fpl = (fpl); \ 3699 MPASS(_fpl->in_smr == true); \ 3700 vfs_smr_exit(); \ 3701 _fpl->in_smr = false; \ 3702 }) 3703 3704 static int 3705 cache_fpl_aborted_impl(struct cache_fpl *fpl, int line) 3706 { 3707 3708 if (fpl->status != CACHE_FPL_STATUS_UNSET) { 3709 KASSERT(fpl->status == CACHE_FPL_STATUS_PARTIAL, 3710 ("%s: converting to abort from %d at %d, set at %d\n", 3711 __func__, fpl->status, line, fpl->line)); 3712 } 3713 fpl->status = CACHE_FPL_STATUS_ABORTED; 3714 fpl->line = line; 3715 return (CACHE_FPL_FAILED); 3716 } 3717 3718 #define cache_fpl_aborted(x) cache_fpl_aborted_impl((x), __LINE__) 3719 3720 static int 3721 cache_fpl_partial_impl(struct cache_fpl *fpl, int line) 3722 { 3723 3724 KASSERT(fpl->status == CACHE_FPL_STATUS_UNSET, 3725 ("%s: setting to partial at %d, but already set to %d at %d\n", 3726 __func__, line, fpl->status, fpl->line)); 3727 cache_fpl_smr_assert_entered(fpl); 3728 fpl->status = CACHE_FPL_STATUS_PARTIAL; 3729 fpl->line = line; 3730 return (CACHE_FPL_FAILED); 3731 } 3732 3733 #define cache_fpl_partial(x) cache_fpl_partial_impl((x), __LINE__) 3734 3735 static int 3736 cache_fpl_handled_impl(struct cache_fpl *fpl, int error, int line) 3737 { 3738 3739 KASSERT(fpl->status == CACHE_FPL_STATUS_UNSET, 3740 ("%s: setting to handled at %d, but already set to %d at %d\n", 3741 __func__, line, fpl->status, fpl->line)); 3742 cache_fpl_smr_assert_not_entered(fpl); 3743 MPASS(error != CACHE_FPL_FAILED); 3744 fpl->status = CACHE_FPL_STATUS_HANDLED; 3745 fpl->line = line; 3746 return (error); 3747 } 3748 3749 #define cache_fpl_handled(x, e) cache_fpl_handled_impl((x), (e), __LINE__) 3750 3751 static bool 3752 cache_fpl_terminated(struct cache_fpl *fpl) 3753 { 3754 3755 return (fpl->status != CACHE_FPL_STATUS_UNSET); 3756 } 3757 3758 #define CACHE_FPL_SUPPORTED_CN_FLAGS \ 3759 (NC_NOMAKEENTRY | NC_KEEPPOSENTRY | LOCKLEAF | LOCKPARENT | WANTPARENT | \ 3760 FAILIFEXISTS | FOLLOW | LOCKSHARED | SAVENAME | SAVESTART | WILLBEDIR | \ 3761 ISOPEN | NOMACCHECK | AUDITVNODE1 | AUDITVNODE2 | NOCAPCHECK) 3762 3763 #define CACHE_FPL_INTERNAL_CN_FLAGS \ 3764 (ISDOTDOT | MAKEENTRY | ISLASTCN) 3765 3766 _Static_assert((CACHE_FPL_SUPPORTED_CN_FLAGS & CACHE_FPL_INTERNAL_CN_FLAGS) == 0, 3767 "supported and internal flags overlap"); 3768 3769 static bool cache_fplookup_is_mp(struct cache_fpl *fpl); 3770 static int cache_fplookup_cross_mount(struct cache_fpl *fpl); 3771 3772 static bool 3773 cache_fpl_islastcn(struct nameidata *ndp) 3774 { 3775 3776 return (*ndp->ni_next == 0); 3777 } 3778 3779 static bool 3780 cache_fpl_isdotdot(struct componentname *cnp) 3781 { 3782 3783 if (cnp->cn_namelen == 2 && 3784 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.') 3785 return (true); 3786 return (false); 3787 } 3788 3789 static bool 3790 cache_can_fplookup(struct cache_fpl *fpl) 3791 { 3792 struct nameidata *ndp; 3793 struct componentname *cnp; 3794 struct thread *td; 3795 3796 ndp = fpl->ndp; 3797 cnp = fpl->cnp; 3798 td = cnp->cn_thread; 3799 3800 if (!cache_fast_lookup) { 3801 cache_fpl_aborted(fpl); 3802 return (false); 3803 } 3804 #ifdef MAC 3805 if (mac_vnode_check_lookup_enabled()) { 3806 cache_fpl_aborted(fpl); 3807 return (false); 3808 } 3809 #endif 3810 if ((cnp->cn_flags & ~CACHE_FPL_SUPPORTED_CN_FLAGS) != 0) { 3811 cache_fpl_aborted(fpl); 3812 return (false); 3813 } 3814 if (IN_CAPABILITY_MODE(td)) { 3815 cache_fpl_aborted(fpl); 3816 return (false); 3817 } 3818 if (AUDITING_TD(td)) { 3819 cache_fpl_aborted(fpl); 3820 return (false); 3821 } 3822 if (ndp->ni_startdir != NULL) { 3823 cache_fpl_aborted(fpl); 3824 return (false); 3825 } 3826 return (true); 3827 } 3828 3829 static int 3830 cache_fplookup_dirfd(struct cache_fpl *fpl, struct vnode **vpp) 3831 { 3832 struct nameidata *ndp; 3833 int error; 3834 bool fsearch; 3835 3836 ndp = fpl->ndp; 3837 error = fgetvp_lookup_smr(ndp->ni_dirfd, ndp, vpp, &fsearch); 3838 if (__predict_false(error != 0)) { 3839 cache_fpl_smr_exit(fpl); 3840 return (cache_fpl_aborted(fpl)); 3841 } 3842 fpl->fsearch = fsearch; 3843 return (0); 3844 } 3845 3846 static bool 3847 cache_fplookup_vnode_supported(struct vnode *vp) 3848 { 3849 3850 return (vp->v_type != VLNK); 3851 } 3852 3853 static int __noinline 3854 cache_fplookup_negative_promote(struct cache_fpl *fpl, struct namecache *oncp, 3855 uint32_t hash) 3856 { 3857 struct componentname *cnp; 3858 struct vnode *dvp; 3859 3860 cnp = fpl->cnp; 3861 dvp = fpl->dvp; 3862 3863 cache_fpl_smr_exit(fpl); 3864 if (cache_neg_promote_cond(dvp, cnp, oncp, hash)) 3865 return (cache_fpl_handled(fpl, ENOENT)); 3866 else 3867 return (cache_fpl_aborted(fpl)); 3868 } 3869 3870 /* 3871 * The target vnode is not supported, prepare for the slow path to take over. 3872 */ 3873 static int __noinline 3874 cache_fplookup_partial_setup(struct cache_fpl *fpl) 3875 { 3876 struct nameidata *ndp; 3877 struct componentname *cnp; 3878 enum vgetstate dvs; 3879 struct vnode *dvp; 3880 struct pwd *pwd; 3881 seqc_t dvp_seqc; 3882 3883 ndp = fpl->ndp; 3884 cnp = fpl->cnp; 3885 pwd = fpl->pwd; 3886 dvp = fpl->dvp; 3887 dvp_seqc = fpl->dvp_seqc; 3888 3889 if (!pwd_hold_smr(pwd)) { 3890 cache_fpl_smr_exit(fpl); 3891 return (cache_fpl_aborted(fpl)); 3892 } 3893 3894 /* 3895 * Note that seqc is checked before the vnode is locked, so by 3896 * the time regular lookup gets to it it may have moved. 3897 * 3898 * Ultimately this does not affect correctness, any lookup errors 3899 * are userspace racing with itself. It is guaranteed that any 3900 * path which ultimatley gets found could also have been found 3901 * by regular lookup going all the way in absence of concurrent 3902 * modifications. 3903 */ 3904 dvs = vget_prep_smr(dvp); 3905 cache_fpl_smr_exit(fpl); 3906 if (__predict_false(dvs == VGET_NONE)) { 3907 pwd_drop(pwd); 3908 return (cache_fpl_aborted(fpl)); 3909 } 3910 3911 vget_finish_ref(dvp, dvs); 3912 if (!vn_seqc_consistent(dvp, dvp_seqc)) { 3913 vrele(dvp); 3914 pwd_drop(pwd); 3915 return (cache_fpl_aborted(fpl)); 3916 } 3917 3918 cache_fpl_restore_partial(fpl, &fpl->snd); 3919 3920 ndp->ni_startdir = dvp; 3921 cnp->cn_flags |= MAKEENTRY; 3922 if (cache_fpl_islastcn(ndp)) 3923 cnp->cn_flags |= ISLASTCN; 3924 if (cache_fpl_isdotdot(cnp)) 3925 cnp->cn_flags |= ISDOTDOT; 3926 3927 return (0); 3928 } 3929 3930 static int 3931 cache_fplookup_final_child(struct cache_fpl *fpl, enum vgetstate tvs) 3932 { 3933 struct componentname *cnp; 3934 struct vnode *tvp; 3935 seqc_t tvp_seqc; 3936 int error, lkflags; 3937 3938 cnp = fpl->cnp; 3939 tvp = fpl->tvp; 3940 tvp_seqc = fpl->tvp_seqc; 3941 3942 if ((cnp->cn_flags & LOCKLEAF) != 0) { 3943 lkflags = LK_SHARED; 3944 if ((cnp->cn_flags & LOCKSHARED) == 0) 3945 lkflags = LK_EXCLUSIVE; 3946 error = vget_finish(tvp, lkflags, tvs); 3947 if (__predict_false(error != 0)) { 3948 return (cache_fpl_aborted(fpl)); 3949 } 3950 } else { 3951 vget_finish_ref(tvp, tvs); 3952 } 3953 3954 if (!vn_seqc_consistent(tvp, tvp_seqc)) { 3955 if ((cnp->cn_flags & LOCKLEAF) != 0) 3956 vput(tvp); 3957 else 3958 vrele(tvp); 3959 return (cache_fpl_aborted(fpl)); 3960 } 3961 3962 return (cache_fpl_handled(fpl, 0)); 3963 } 3964 3965 /* 3966 * They want to possibly modify the state of the namecache. 3967 */ 3968 static int __noinline 3969 cache_fplookup_final_modifying(struct cache_fpl *fpl) 3970 { 3971 struct nameidata *ndp; 3972 struct componentname *cnp; 3973 enum vgetstate dvs; 3974 struct vnode *dvp, *tvp; 3975 struct mount *mp; 3976 seqc_t dvp_seqc; 3977 int error; 3978 bool docache; 3979 3980 ndp = fpl->ndp; 3981 cnp = fpl->cnp; 3982 dvp = fpl->dvp; 3983 dvp_seqc = fpl->dvp_seqc; 3984 3985 MPASS(cache_fpl_islastcn(ndp)); 3986 if ((cnp->cn_flags & LOCKPARENT) == 0) 3987 MPASS((cnp->cn_flags & WANTPARENT) != 0); 3988 MPASS((cnp->cn_flags & TRAILINGSLASH) == 0); 3989 MPASS(cnp->cn_nameiop == CREATE || cnp->cn_nameiop == DELETE || 3990 cnp->cn_nameiop == RENAME); 3991 MPASS((cnp->cn_flags & MAKEENTRY) == 0); 3992 MPASS((cnp->cn_flags & ISDOTDOT) == 0); 3993 3994 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE; 3995 if (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME) 3996 docache = false; 3997 3998 mp = atomic_load_ptr(&dvp->v_mount); 3999 if (__predict_false(mp == NULL)) { 4000 return (cache_fpl_aborted(fpl)); 4001 } 4002 4003 if (__predict_false(mp->mnt_flag & MNT_RDONLY)) { 4004 cache_fpl_smr_exit(fpl); 4005 /* 4006 * Original code keeps not checking for CREATE which 4007 * might be a bug. For now let the old lookup decide. 4008 */ 4009 if (cnp->cn_nameiop == CREATE) { 4010 return (cache_fpl_aborted(fpl)); 4011 } 4012 return (cache_fpl_handled(fpl, EROFS)); 4013 } 4014 4015 if (fpl->tvp != NULL && (cnp->cn_flags & FAILIFEXISTS) != 0) { 4016 cache_fpl_smr_exit(fpl); 4017 return (cache_fpl_handled(fpl, EEXIST)); 4018 } 4019 4020 /* 4021 * Secure access to dvp; check cache_fplookup_partial_setup for 4022 * reasoning. 4023 * 4024 * XXX At least UFS requires its lookup routine to be called for 4025 * the last path component, which leads to some level of complicaton 4026 * and inefficiency: 4027 * - the target routine always locks the target vnode, but our caller 4028 * may not need it locked 4029 * - some of the VOP machinery asserts that the parent is locked, which 4030 * once more may be not required 4031 * 4032 * TODO: add a flag for filesystems which don't need this. 4033 */ 4034 dvs = vget_prep_smr(dvp); 4035 cache_fpl_smr_exit(fpl); 4036 if (__predict_false(dvs == VGET_NONE)) { 4037 return (cache_fpl_aborted(fpl)); 4038 } 4039 4040 vget_finish_ref(dvp, dvs); 4041 if (!vn_seqc_consistent(dvp, dvp_seqc)) { 4042 vrele(dvp); 4043 return (cache_fpl_aborted(fpl)); 4044 } 4045 4046 error = vn_lock(dvp, LK_EXCLUSIVE); 4047 if (__predict_false(error != 0)) { 4048 vrele(dvp); 4049 return (cache_fpl_aborted(fpl)); 4050 } 4051 4052 tvp = NULL; 4053 cnp->cn_flags |= ISLASTCN; 4054 if (docache) 4055 cnp->cn_flags |= MAKEENTRY; 4056 if (cache_fpl_isdotdot(cnp)) 4057 cnp->cn_flags |= ISDOTDOT; 4058 cnp->cn_lkflags = LK_EXCLUSIVE; 4059 error = VOP_LOOKUP(dvp, &tvp, cnp); 4060 switch (error) { 4061 case EJUSTRETURN: 4062 case 0: 4063 break; 4064 case ENOTDIR: 4065 case ENOENT: 4066 vput(dvp); 4067 return (cache_fpl_handled(fpl, error)); 4068 default: 4069 vput(dvp); 4070 return (cache_fpl_aborted(fpl)); 4071 } 4072 4073 fpl->tvp = tvp; 4074 4075 if (tvp == NULL) { 4076 if ((cnp->cn_flags & SAVESTART) != 0) { 4077 ndp->ni_startdir = dvp; 4078 vrefact(ndp->ni_startdir); 4079 cnp->cn_flags |= SAVENAME; 4080 } 4081 MPASS(error == EJUSTRETURN); 4082 if ((cnp->cn_flags & LOCKPARENT) == 0) { 4083 VOP_UNLOCK(dvp); 4084 } 4085 return (cache_fpl_handled(fpl, 0)); 4086 } 4087 4088 /* 4089 * There are very hairy corner cases concerning various flag combinations 4090 * and locking state. In particular here we only hold one lock instead of 4091 * two. 4092 * 4093 * Skip the complexity as it is of no significance for normal workloads. 4094 */ 4095 if (__predict_false(tvp == dvp)) { 4096 vput(dvp); 4097 vrele(tvp); 4098 return (cache_fpl_aborted(fpl)); 4099 } 4100 4101 /* 4102 * Check if the target is either a symlink or a mount point. 4103 * Since we expect this to be the terminal vnode it should 4104 * almost never be true. 4105 */ 4106 if (__predict_false(!cache_fplookup_vnode_supported(tvp) || 4107 cache_fplookup_is_mp(fpl))) { 4108 vput(dvp); 4109 vput(tvp); 4110 return (cache_fpl_aborted(fpl)); 4111 } 4112 4113 if ((cnp->cn_flags & FAILIFEXISTS) != 0) { 4114 vput(dvp); 4115 vput(tvp); 4116 return (cache_fpl_handled(fpl, EEXIST)); 4117 } 4118 4119 if ((cnp->cn_flags & LOCKLEAF) == 0) { 4120 VOP_UNLOCK(tvp); 4121 } 4122 4123 if ((cnp->cn_flags & LOCKPARENT) == 0) { 4124 VOP_UNLOCK(dvp); 4125 } 4126 4127 if ((cnp->cn_flags & SAVESTART) != 0) { 4128 ndp->ni_startdir = dvp; 4129 vrefact(ndp->ni_startdir); 4130 cnp->cn_flags |= SAVENAME; 4131 } 4132 4133 return (cache_fpl_handled(fpl, 0)); 4134 } 4135 4136 static int __noinline 4137 cache_fplookup_modifying(struct cache_fpl *fpl) 4138 { 4139 struct nameidata *ndp; 4140 4141 ndp = fpl->ndp; 4142 4143 if (!cache_fpl_islastcn(ndp)) { 4144 return (cache_fpl_partial(fpl)); 4145 } 4146 return (cache_fplookup_final_modifying(fpl)); 4147 } 4148 4149 static int __noinline 4150 cache_fplookup_final_withparent(struct cache_fpl *fpl) 4151 { 4152 struct componentname *cnp; 4153 enum vgetstate dvs, tvs; 4154 struct vnode *dvp, *tvp; 4155 seqc_t dvp_seqc; 4156 int error; 4157 4158 cnp = fpl->cnp; 4159 dvp = fpl->dvp; 4160 dvp_seqc = fpl->dvp_seqc; 4161 tvp = fpl->tvp; 4162 4163 MPASS((cnp->cn_flags & (LOCKPARENT|WANTPARENT)) != 0); 4164 4165 /* 4166 * This is less efficient than it can be for simplicity. 4167 */ 4168 dvs = vget_prep_smr(dvp); 4169 if (__predict_false(dvs == VGET_NONE)) { 4170 return (cache_fpl_aborted(fpl)); 4171 } 4172 tvs = vget_prep_smr(tvp); 4173 if (__predict_false(tvs == VGET_NONE)) { 4174 cache_fpl_smr_exit(fpl); 4175 vget_abort(dvp, dvs); 4176 return (cache_fpl_aborted(fpl)); 4177 } 4178 4179 cache_fpl_smr_exit(fpl); 4180 4181 if ((cnp->cn_flags & LOCKPARENT) != 0) { 4182 error = vget_finish(dvp, LK_EXCLUSIVE, dvs); 4183 if (__predict_false(error != 0)) { 4184 vget_abort(tvp, tvs); 4185 return (cache_fpl_aborted(fpl)); 4186 } 4187 } else { 4188 vget_finish_ref(dvp, dvs); 4189 } 4190 4191 if (!vn_seqc_consistent(dvp, dvp_seqc)) { 4192 vget_abort(tvp, tvs); 4193 if ((cnp->cn_flags & LOCKPARENT) != 0) 4194 vput(dvp); 4195 else 4196 vrele(dvp); 4197 return (cache_fpl_aborted(fpl)); 4198 } 4199 4200 error = cache_fplookup_final_child(fpl, tvs); 4201 if (__predict_false(error != 0)) { 4202 MPASS(fpl->status == CACHE_FPL_STATUS_ABORTED); 4203 if ((cnp->cn_flags & LOCKPARENT) != 0) 4204 vput(dvp); 4205 else 4206 vrele(dvp); 4207 return (error); 4208 } 4209 4210 MPASS(fpl->status == CACHE_FPL_STATUS_HANDLED); 4211 return (0); 4212 } 4213 4214 static int 4215 cache_fplookup_final(struct cache_fpl *fpl) 4216 { 4217 struct componentname *cnp; 4218 enum vgetstate tvs; 4219 struct vnode *dvp, *tvp; 4220 seqc_t dvp_seqc; 4221 4222 cnp = fpl->cnp; 4223 dvp = fpl->dvp; 4224 dvp_seqc = fpl->dvp_seqc; 4225 tvp = fpl->tvp; 4226 4227 if (cnp->cn_nameiop != LOOKUP) { 4228 return (cache_fplookup_final_modifying(fpl)); 4229 } 4230 4231 if ((cnp->cn_flags & (LOCKPARENT|WANTPARENT)) != 0) 4232 return (cache_fplookup_final_withparent(fpl)); 4233 4234 tvs = vget_prep_smr(tvp); 4235 if (__predict_false(tvs == VGET_NONE)) { 4236 return (cache_fpl_partial(fpl)); 4237 } 4238 4239 if (!vn_seqc_consistent(dvp, dvp_seqc)) { 4240 cache_fpl_smr_exit(fpl); 4241 vget_abort(tvp, tvs); 4242 return (cache_fpl_aborted(fpl)); 4243 } 4244 4245 cache_fpl_smr_exit(fpl); 4246 return (cache_fplookup_final_child(fpl, tvs)); 4247 } 4248 4249 /* 4250 * Comment from locked lookup: 4251 * Check for degenerate name (e.g. / or "") which is a way of talking about a 4252 * directory, e.g. like "/." or ".". 4253 */ 4254 static int __noinline 4255 cache_fplookup_degenerate(struct cache_fpl *fpl) 4256 { 4257 struct componentname *cnp; 4258 struct vnode *dvp; 4259 enum vgetstate dvs; 4260 int error, lkflags; 4261 4262 fpl->tvp = fpl->dvp; 4263 fpl->tvp_seqc = fpl->dvp_seqc; 4264 4265 cnp = fpl->cnp; 4266 dvp = fpl->dvp; 4267 4268 if (__predict_false(cnp->cn_nameiop != LOOKUP)) { 4269 cache_fpl_smr_exit(fpl); 4270 return (cache_fpl_handled(fpl, EISDIR)); 4271 } 4272 4273 MPASS((cnp->cn_flags & SAVESTART) == 0); 4274 4275 if ((cnp->cn_flags & (LOCKPARENT|WANTPARENT)) != 0) { 4276 return (cache_fplookup_final_withparent(fpl)); 4277 } 4278 4279 dvs = vget_prep_smr(dvp); 4280 cache_fpl_smr_exit(fpl); 4281 if (__predict_false(dvs == VGET_NONE)) { 4282 return (cache_fpl_aborted(fpl)); 4283 } 4284 4285 if ((cnp->cn_flags & LOCKLEAF) != 0) { 4286 lkflags = LK_SHARED; 4287 if ((cnp->cn_flags & LOCKSHARED) == 0) 4288 lkflags = LK_EXCLUSIVE; 4289 error = vget_finish(dvp, lkflags, dvs); 4290 if (__predict_false(error != 0)) { 4291 return (cache_fpl_aborted(fpl)); 4292 } 4293 } else { 4294 vget_finish_ref(dvp, dvs); 4295 } 4296 return (cache_fpl_handled(fpl, 0)); 4297 } 4298 4299 static int __noinline 4300 cache_fplookup_noentry(struct cache_fpl *fpl) 4301 { 4302 struct nameidata *ndp; 4303 struct componentname *cnp; 4304 enum vgetstate dvs; 4305 struct vnode *dvp, *tvp; 4306 seqc_t dvp_seqc; 4307 int error; 4308 bool docache; 4309 4310 ndp = fpl->ndp; 4311 cnp = fpl->cnp; 4312 dvp = fpl->dvp; 4313 dvp_seqc = fpl->dvp_seqc; 4314 4315 MPASS((cnp->cn_flags & MAKEENTRY) == 0); 4316 MPASS((cnp->cn_flags & ISDOTDOT) == 0); 4317 MPASS(!cache_fpl_isdotdot(cnp)); 4318 4319 /* 4320 * Hack: delayed name len checking. 4321 */ 4322 if (__predict_false(cnp->cn_namelen > NAME_MAX)) { 4323 cache_fpl_smr_exit(fpl); 4324 return (cache_fpl_handled(fpl, ENAMETOOLONG)); 4325 } 4326 4327 if (cnp->cn_nameiop != LOOKUP) { 4328 fpl->tvp = NULL; 4329 return (cache_fplookup_modifying(fpl)); 4330 } 4331 4332 MPASS((cnp->cn_flags & SAVESTART) == 0); 4333 4334 /* 4335 * Only try to fill in the component if it is the last one, 4336 * otherwise not only there may be several to handle but the 4337 * walk may be complicated. 4338 */ 4339 if (!cache_fpl_islastcn(ndp)) { 4340 return (cache_fpl_partial(fpl)); 4341 } 4342 4343 /* 4344 * Secure access to dvp; check cache_fplookup_partial_setup for 4345 * reasoning. 4346 */ 4347 dvs = vget_prep_smr(dvp); 4348 cache_fpl_smr_exit(fpl); 4349 if (__predict_false(dvs == VGET_NONE)) { 4350 return (cache_fpl_aborted(fpl)); 4351 } 4352 4353 vget_finish_ref(dvp, dvs); 4354 if (!vn_seqc_consistent(dvp, dvp_seqc)) { 4355 vrele(dvp); 4356 return (cache_fpl_aborted(fpl)); 4357 } 4358 4359 error = vn_lock(dvp, LK_SHARED); 4360 if (__predict_false(error != 0)) { 4361 vrele(dvp); 4362 return (cache_fpl_aborted(fpl)); 4363 } 4364 4365 tvp = NULL; 4366 /* 4367 * TODO: provide variants which don't require locking either vnode. 4368 */ 4369 cnp->cn_flags |= ISLASTCN; 4370 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE; 4371 if (docache) 4372 cnp->cn_flags |= MAKEENTRY; 4373 cnp->cn_lkflags = LK_SHARED; 4374 if ((cnp->cn_flags & LOCKSHARED) == 0) { 4375 cnp->cn_lkflags = LK_EXCLUSIVE; 4376 } 4377 error = VOP_LOOKUP(dvp, &tvp, cnp); 4378 switch (error) { 4379 case EJUSTRETURN: 4380 case 0: 4381 break; 4382 case ENOTDIR: 4383 case ENOENT: 4384 vput(dvp); 4385 return (cache_fpl_handled(fpl, error)); 4386 default: 4387 vput(dvp); 4388 return (cache_fpl_aborted(fpl)); 4389 } 4390 4391 fpl->tvp = tvp; 4392 4393 if (tvp == NULL) { 4394 MPASS(error == EJUSTRETURN); 4395 if ((cnp->cn_flags & (WANTPARENT | LOCKPARENT)) == 0) { 4396 vput(dvp); 4397 } else if ((cnp->cn_flags & LOCKPARENT) == 0) { 4398 VOP_UNLOCK(dvp); 4399 } 4400 return (cache_fpl_handled(fpl, 0)); 4401 } 4402 4403 if (__predict_false(!cache_fplookup_vnode_supported(tvp) || 4404 cache_fplookup_is_mp(fpl))) { 4405 vput(dvp); 4406 vput(tvp); 4407 return (cache_fpl_aborted(fpl)); 4408 } 4409 4410 if ((cnp->cn_flags & LOCKLEAF) == 0) { 4411 VOP_UNLOCK(tvp); 4412 } 4413 4414 if ((cnp->cn_flags & (WANTPARENT | LOCKPARENT)) == 0) { 4415 vput(dvp); 4416 } else if ((cnp->cn_flags & LOCKPARENT) == 0) { 4417 VOP_UNLOCK(dvp); 4418 } 4419 return (cache_fpl_handled(fpl, 0)); 4420 } 4421 4422 static int __noinline 4423 cache_fplookup_dot(struct cache_fpl *fpl) 4424 { 4425 int error; 4426 4427 MPASS(!seqc_in_modify(fpl->dvp_seqc)); 4428 /* 4429 * Just re-assign the value. seqc will be checked later for the first 4430 * non-dot path component in line and/or before deciding to return the 4431 * vnode. 4432 */ 4433 fpl->tvp = fpl->dvp; 4434 fpl->tvp_seqc = fpl->dvp_seqc; 4435 if (cache_fplookup_is_mp(fpl)) { 4436 error = cache_fplookup_cross_mount(fpl); 4437 if (__predict_false(error != 0)) { 4438 return (error); 4439 } 4440 } 4441 4442 counter_u64_add(dothits, 1); 4443 SDT_PROBE3(vfs, namecache, lookup, hit, fpl->dvp, ".", fpl->dvp); 4444 return (0); 4445 } 4446 4447 static int __noinline 4448 cache_fplookup_dotdot(struct cache_fpl *fpl) 4449 { 4450 struct nameidata *ndp; 4451 struct componentname *cnp; 4452 struct namecache *ncp; 4453 struct vnode *dvp; 4454 struct prison *pr; 4455 u_char nc_flag; 4456 4457 ndp = fpl->ndp; 4458 cnp = fpl->cnp; 4459 dvp = fpl->dvp; 4460 4461 MPASS(cache_fpl_isdotdot(cnp)); 4462 4463 /* 4464 * XXX this is racy the same way regular lookup is 4465 */ 4466 for (pr = cnp->cn_cred->cr_prison; pr != NULL; 4467 pr = pr->pr_parent) 4468 if (dvp == pr->pr_root) 4469 break; 4470 4471 if (dvp == ndp->ni_rootdir || 4472 dvp == ndp->ni_topdir || 4473 dvp == rootvnode || 4474 pr != NULL) { 4475 fpl->tvp = dvp; 4476 fpl->tvp_seqc = vn_seqc_read_any(dvp); 4477 if (seqc_in_modify(fpl->tvp_seqc)) { 4478 return (cache_fpl_aborted(fpl)); 4479 } 4480 return (0); 4481 } 4482 4483 if ((dvp->v_vflag & VV_ROOT) != 0) { 4484 /* 4485 * TODO 4486 * The opposite of climb mount is needed here. 4487 */ 4488 return (cache_fpl_aborted(fpl)); 4489 } 4490 4491 ncp = atomic_load_ptr(&dvp->v_cache_dd); 4492 if (ncp == NULL) { 4493 return (cache_fpl_aborted(fpl)); 4494 } 4495 4496 nc_flag = atomic_load_char(&ncp->nc_flag); 4497 if ((nc_flag & NCF_ISDOTDOT) != 0) { 4498 if ((nc_flag & NCF_NEGATIVE) != 0) 4499 return (cache_fpl_aborted(fpl)); 4500 fpl->tvp = ncp->nc_vp; 4501 } else { 4502 fpl->tvp = ncp->nc_dvp; 4503 } 4504 4505 if (!cache_ncp_canuse(ncp)) { 4506 return (cache_fpl_aborted(fpl)); 4507 } 4508 4509 fpl->tvp_seqc = vn_seqc_read_any(fpl->tvp); 4510 if (seqc_in_modify(fpl->tvp_seqc)) { 4511 return (cache_fpl_partial(fpl)); 4512 } 4513 4514 counter_u64_add(dotdothits, 1); 4515 return (0); 4516 } 4517 4518 static int __noinline 4519 cache_fplookup_neg(struct cache_fpl *fpl, struct namecache *ncp, uint32_t hash) 4520 { 4521 u_char nc_flag; 4522 bool neg_promote; 4523 4524 nc_flag = atomic_load_char(&ncp->nc_flag); 4525 MPASS((nc_flag & NCF_NEGATIVE) != 0); 4526 /* 4527 * If they want to create an entry we need to replace this one. 4528 */ 4529 if (__predict_false(fpl->cnp->cn_nameiop != LOOKUP)) { 4530 fpl->tvp = NULL; 4531 return (cache_fplookup_modifying(fpl)); 4532 } 4533 neg_promote = cache_neg_hit_prep(ncp); 4534 if (!cache_fpl_neg_ncp_canuse(ncp)) { 4535 cache_neg_hit_abort(ncp); 4536 return (cache_fpl_partial(fpl)); 4537 } 4538 if (neg_promote) { 4539 return (cache_fplookup_negative_promote(fpl, ncp, hash)); 4540 } 4541 cache_neg_hit_finish(ncp); 4542 cache_fpl_smr_exit(fpl); 4543 return (cache_fpl_handled(fpl, ENOENT)); 4544 } 4545 4546 static int 4547 cache_fplookup_next(struct cache_fpl *fpl) 4548 { 4549 struct componentname *cnp; 4550 struct namecache *ncp; 4551 struct vnode *dvp, *tvp; 4552 u_char nc_flag; 4553 uint32_t hash; 4554 int error; 4555 4556 cnp = fpl->cnp; 4557 dvp = fpl->dvp; 4558 4559 if (__predict_false(cnp->cn_nameptr[0] == '.')) { 4560 if (cnp->cn_namelen == 1) { 4561 return (cache_fplookup_dot(fpl)); 4562 } 4563 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 4564 return (cache_fplookup_dotdot(fpl)); 4565 } 4566 } 4567 4568 MPASS(!cache_fpl_isdotdot(cnp)); 4569 4570 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp); 4571 4572 CK_SLIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 4573 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 4574 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 4575 break; 4576 } 4577 4578 if (__predict_false(ncp == NULL)) { 4579 return (cache_fplookup_noentry(fpl)); 4580 } 4581 4582 tvp = atomic_load_ptr(&ncp->nc_vp); 4583 nc_flag = atomic_load_char(&ncp->nc_flag); 4584 if ((nc_flag & NCF_NEGATIVE) != 0) { 4585 return (cache_fplookup_neg(fpl, ncp, hash)); 4586 } 4587 4588 if (!cache_ncp_canuse(ncp)) { 4589 return (cache_fpl_partial(fpl)); 4590 } 4591 4592 fpl->tvp = tvp; 4593 fpl->tvp_seqc = vn_seqc_read_any(tvp); 4594 if (seqc_in_modify(fpl->tvp_seqc)) { 4595 return (cache_fpl_partial(fpl)); 4596 } 4597 4598 if (!cache_fplookup_vnode_supported(tvp)) { 4599 return (cache_fpl_partial(fpl)); 4600 } 4601 4602 if (cache_fplookup_is_mp(fpl)) { 4603 error = cache_fplookup_cross_mount(fpl); 4604 if (__predict_false(error != 0)) { 4605 return (error); 4606 } 4607 } 4608 4609 counter_u64_add(numposhits, 1); 4610 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ncp->nc_name, tvp); 4611 return (0); 4612 } 4613 4614 static bool 4615 cache_fplookup_mp_supported(struct mount *mp) 4616 { 4617 4618 MPASS(mp != NULL); 4619 if ((mp->mnt_kern_flag & MNTK_FPLOOKUP) == 0) 4620 return (false); 4621 return (true); 4622 } 4623 4624 /* 4625 * Walk up the mount stack (if any). 4626 * 4627 * Correctness is provided in the following ways: 4628 * - all vnodes are protected from freeing with SMR 4629 * - struct mount objects are type stable making them always safe to access 4630 * - stability of the particular mount is provided by busying it 4631 * - relationship between the vnode which is mounted on and the mount is 4632 * verified with the vnode sequence counter after busying 4633 * - association between root vnode of the mount and the mount is protected 4634 * by busy 4635 * 4636 * From that point on we can read the sequence counter of the root vnode 4637 * and get the next mount on the stack (if any) using the same protection. 4638 * 4639 * By the end of successful walk we are guaranteed the reached state was 4640 * indeed present at least at some point which matches the regular lookup. 4641 */ 4642 static int __noinline 4643 cache_fplookup_climb_mount(struct cache_fpl *fpl) 4644 { 4645 struct mount *mp, *prev_mp; 4646 struct mount_pcpu *mpcpu, *prev_mpcpu; 4647 struct vnode *vp; 4648 seqc_t vp_seqc; 4649 4650 vp = fpl->tvp; 4651 vp_seqc = fpl->tvp_seqc; 4652 4653 VNPASS(vp->v_type == VDIR || vp->v_type == VBAD, vp); 4654 mp = atomic_load_ptr(&vp->v_mountedhere); 4655 if (__predict_false(mp == NULL)) { 4656 return (0); 4657 } 4658 4659 prev_mp = NULL; 4660 for (;;) { 4661 if (!vfs_op_thread_enter_crit(mp, mpcpu)) { 4662 if (prev_mp != NULL) 4663 vfs_op_thread_exit_crit(prev_mp, prev_mpcpu); 4664 return (cache_fpl_partial(fpl)); 4665 } 4666 if (prev_mp != NULL) 4667 vfs_op_thread_exit_crit(prev_mp, prev_mpcpu); 4668 if (!vn_seqc_consistent(vp, vp_seqc)) { 4669 vfs_op_thread_exit_crit(mp, mpcpu); 4670 return (cache_fpl_partial(fpl)); 4671 } 4672 if (!cache_fplookup_mp_supported(mp)) { 4673 vfs_op_thread_exit_crit(mp, mpcpu); 4674 return (cache_fpl_partial(fpl)); 4675 } 4676 vp = atomic_load_ptr(&mp->mnt_rootvnode); 4677 if (vp == NULL || VN_IS_DOOMED(vp)) { 4678 vfs_op_thread_exit_crit(mp, mpcpu); 4679 return (cache_fpl_partial(fpl)); 4680 } 4681 vp_seqc = vn_seqc_read_any(vp); 4682 if (seqc_in_modify(vp_seqc)) { 4683 vfs_op_thread_exit_crit(mp, mpcpu); 4684 return (cache_fpl_partial(fpl)); 4685 } 4686 prev_mp = mp; 4687 prev_mpcpu = mpcpu; 4688 mp = atomic_load_ptr(&vp->v_mountedhere); 4689 if (mp == NULL) 4690 break; 4691 } 4692 4693 vfs_op_thread_exit_crit(prev_mp, prev_mpcpu); 4694 fpl->tvp = vp; 4695 fpl->tvp_seqc = vp_seqc; 4696 return (0); 4697 } 4698 4699 static int __noinline 4700 cache_fplookup_cross_mount(struct cache_fpl *fpl) 4701 { 4702 struct mount *mp; 4703 struct mount_pcpu *mpcpu; 4704 struct vnode *vp; 4705 seqc_t vp_seqc; 4706 4707 vp = fpl->tvp; 4708 vp_seqc = fpl->tvp_seqc; 4709 4710 VNPASS(vp->v_type == VDIR || vp->v_type == VBAD, vp); 4711 mp = atomic_load_ptr(&vp->v_mountedhere); 4712 if (__predict_false(mp == NULL)) { 4713 return (0); 4714 } 4715 4716 if (!vfs_op_thread_enter_crit(mp, mpcpu)) { 4717 return (cache_fpl_partial(fpl)); 4718 } 4719 if (!vn_seqc_consistent(vp, vp_seqc)) { 4720 vfs_op_thread_exit_crit(mp, mpcpu); 4721 return (cache_fpl_partial(fpl)); 4722 } 4723 if (!cache_fplookup_mp_supported(mp)) { 4724 vfs_op_thread_exit_crit(mp, mpcpu); 4725 return (cache_fpl_partial(fpl)); 4726 } 4727 vp = atomic_load_ptr(&mp->mnt_rootvnode); 4728 if (__predict_false(vp == NULL || VN_IS_DOOMED(vp))) { 4729 vfs_op_thread_exit_crit(mp, mpcpu); 4730 return (cache_fpl_partial(fpl)); 4731 } 4732 vp_seqc = vn_seqc_read_any(vp); 4733 vfs_op_thread_exit_crit(mp, mpcpu); 4734 if (seqc_in_modify(vp_seqc)) { 4735 return (cache_fpl_partial(fpl)); 4736 } 4737 mp = atomic_load_ptr(&vp->v_mountedhere); 4738 if (__predict_false(mp != NULL)) { 4739 /* 4740 * There are possibly more mount points on top. 4741 * Normally this does not happen so for simplicity just start 4742 * over. 4743 */ 4744 return (cache_fplookup_climb_mount(fpl)); 4745 } 4746 4747 fpl->tvp = vp; 4748 fpl->tvp_seqc = vp_seqc; 4749 return (0); 4750 } 4751 4752 /* 4753 * Check if a vnode is mounted on. 4754 */ 4755 static bool 4756 cache_fplookup_is_mp(struct cache_fpl *fpl) 4757 { 4758 struct vnode *vp; 4759 4760 vp = fpl->tvp; 4761 return ((vn_irflag_read(vp) & VIRF_MOUNTPOINT) != 0); 4762 } 4763 4764 /* 4765 * Parse the path. 4766 * 4767 * The code was originally copy-pasted from regular lookup and despite 4768 * clean ups leaves performance on the table. Any modifications here 4769 * must take into account that in case off fallback the resulting 4770 * nameidata state has to be compatible with the original. 4771 */ 4772 static int 4773 cache_fplookup_preparse(struct cache_fpl *fpl) 4774 { 4775 struct nameidata *ndp; 4776 struct componentname *cnp; 4777 4778 ndp = fpl->ndp; 4779 cnp = fpl->cnp; 4780 4781 if (__predict_false(cnp->cn_nameptr[0] == '\0')) { 4782 return (cache_fplookup_degenerate(fpl)); 4783 } 4784 4785 /* 4786 * By this point the shortest possible pathname is one character + nul 4787 * terminator, hence 2. 4788 */ 4789 KASSERT(ndp->ni_pathlen >= 2, ("%s: ni_pathlen %zu\n", __func__, 4790 ndp->ni_pathlen)); 4791 4792 if (__predict_false(cnp->cn_nameptr[ndp->ni_pathlen - 2] == '/')) { 4793 /* 4794 * TODO 4795 * Regular lookup performs the following: 4796 * *ndp->ni_next = '\0'; 4797 * cnp->cn_flags |= TRAILINGSLASH; 4798 * 4799 * Which is problematic since it modifies data read 4800 * from userspace. Then if fast path lookup was to 4801 * abort we would have to either restore it or convey 4802 * the flag. Since this is a corner case just ignore 4803 * it for simplicity. 4804 */ 4805 return (cache_fpl_aborted(fpl)); 4806 } 4807 return (0); 4808 } 4809 4810 static int 4811 cache_fplookup_parse(struct cache_fpl *fpl) 4812 { 4813 struct nameidata *ndp; 4814 struct componentname *cnp; 4815 char *cp; 4816 4817 ndp = fpl->ndp; 4818 cnp = fpl->cnp; 4819 4820 /* 4821 * Find the end of this path component, it is either / or nul. 4822 * 4823 * Store / as a temporary sentinel so that we only have one character 4824 * to test for. Pathnames tend to be short so this should not be 4825 * resulting in cache misses. 4826 */ 4827 KASSERT(cnp->cn_nameptr[ndp->ni_pathlen - 1] == '\0', 4828 ("%s: expected nul at %p + %zu; string [%s]\n", __func__, 4829 cnp->cn_nameptr, ndp->ni_pathlen - 1, cnp->cn_nameptr)); 4830 cnp->cn_nameptr[ndp->ni_pathlen - 1] = '/'; 4831 for (cp = cnp->cn_nameptr; *cp != '/'; cp++) { 4832 KASSERT(*cp != '\0', 4833 ("%s: encountered unexpected nul; string [%s]\n", __func__, 4834 cnp->cn_nameptr)); 4835 continue; 4836 } 4837 cnp->cn_nameptr[ndp->ni_pathlen - 1] = '\0'; 4838 4839 cnp->cn_namelen = cp - cnp->cn_nameptr; 4840 ndp->ni_pathlen -= cnp->cn_namelen; 4841 KASSERT(ndp->ni_pathlen <= PATH_MAX, 4842 ("%s: ni_pathlen underflow to %zd\n", __func__, ndp->ni_pathlen)); 4843 /* 4844 * Hack: we have to check if the found path component's length exceeds 4845 * NAME_MAX. However, the condition is very rarely true and check can 4846 * be elided in the common case -- if an entry was found in the cache, 4847 * then it could not have been too long to begin with. 4848 */ 4849 ndp->ni_next = cp; 4850 4851 #ifdef INVARIANTS 4852 /* 4853 * Code below is only here to assure compatibility with regular lookup. 4854 * It covers handling of trailing slashles and names like "/", both of 4855 * which of can be taken care of upfront which lockless lookup does 4856 * in cache_fplookup_preparse. Regular lookup performs these for each 4857 * path component. 4858 */ 4859 while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) { 4860 cp++; 4861 if (*cp == '\0') { 4862 panic("%s: ran into TRAILINGSLASH handling from [%s]\n", 4863 __func__, cnp->cn_pnbuf); 4864 } 4865 } 4866 4867 if (cnp->cn_nameptr[0] == '\0') { 4868 panic("%s: ran into degenerate name from [%s]\n", __func__, cnp->cn_pnbuf); 4869 } 4870 #endif 4871 return (0); 4872 } 4873 4874 static void 4875 cache_fplookup_parse_advance(struct cache_fpl *fpl) 4876 { 4877 struct nameidata *ndp; 4878 struct componentname *cnp; 4879 4880 ndp = fpl->ndp; 4881 cnp = fpl->cnp; 4882 4883 cnp->cn_nameptr = ndp->ni_next; 4884 while (*cnp->cn_nameptr == '/') { 4885 cnp->cn_nameptr++; 4886 ndp->ni_pathlen--; 4887 } 4888 } 4889 4890 /* 4891 * See the API contract for VOP_FPLOOKUP_VEXEC. 4892 */ 4893 static int __noinline 4894 cache_fplookup_failed_vexec(struct cache_fpl *fpl, int error) 4895 { 4896 struct componentname *cnp; 4897 struct vnode *dvp; 4898 seqc_t dvp_seqc; 4899 4900 cnp = fpl->cnp; 4901 dvp = fpl->dvp; 4902 dvp_seqc = fpl->dvp_seqc; 4903 4904 /* 4905 * Hack: delayed name len checking. 4906 */ 4907 if (__predict_false(cnp->cn_namelen > NAME_MAX)) { 4908 cache_fpl_smr_exit(fpl); 4909 return (cache_fpl_handled(fpl, ENAMETOOLONG)); 4910 } 4911 4912 /* 4913 * Hack: they may be looking up foo/bar, where foo is a 4914 * regular file. In such a case we need to turn ENOTDIR, 4915 * but we may happen to get here with a different error. 4916 */ 4917 if (dvp->v_type != VDIR) { 4918 /* 4919 * The check here is predominantly to catch 4920 * EOPNOTSUPP from dead_vnodeops. If the vnode 4921 * gets doomed past this point it is going to 4922 * fail seqc verification. 4923 */ 4924 if (VN_IS_DOOMED(dvp)) { 4925 return (cache_fpl_aborted(fpl)); 4926 } 4927 error = ENOTDIR; 4928 } 4929 4930 /* 4931 * Hack: handle O_SEARCH. 4932 * 4933 * Open Group Base Specifications Issue 7, 2018 edition states: 4934 * If the access mode of the open file description associated with the 4935 * file descriptor is not O_SEARCH, the function shall check whether 4936 * directory searches are permitted using the current permissions of 4937 * the directory underlying the file descriptor. If the access mode is 4938 * O_SEARCH, the function shall not perform the check. 4939 * 4940 * Regular lookup tests for the NOEXECCHECK flag for every path 4941 * component to decide whether to do the permission check. However, 4942 * since most lookups never have the flag (and when they do it is only 4943 * present for the first path component), lockless lookup only acts on 4944 * it if there is a permission problem. Here the flag is represented 4945 * with a boolean so that we don't have to clear it on the way out. 4946 * 4947 * For simplicity this always aborts. 4948 * TODO: check if this is the first lookup and ignore the permission 4949 * problem. Note the flag has to survive fallback (if it happens to be 4950 * performed). 4951 */ 4952 if (fpl->fsearch) { 4953 return (cache_fpl_aborted(fpl)); 4954 } 4955 4956 switch (error) { 4957 case EAGAIN: 4958 if (!vn_seqc_consistent(dvp, dvp_seqc)) { 4959 error = cache_fpl_aborted(fpl); 4960 } else { 4961 cache_fpl_partial(fpl); 4962 } 4963 break; 4964 default: 4965 if (!vn_seqc_consistent(dvp, dvp_seqc)) { 4966 error = cache_fpl_aborted(fpl); 4967 } else { 4968 cache_fpl_smr_exit(fpl); 4969 cache_fpl_handled(fpl, error); 4970 } 4971 break; 4972 } 4973 return (error); 4974 } 4975 4976 static int 4977 cache_fplookup_impl(struct vnode *dvp, struct cache_fpl *fpl) 4978 { 4979 struct nameidata *ndp; 4980 struct componentname *cnp; 4981 struct mount *mp; 4982 int error; 4983 4984 error = CACHE_FPL_FAILED; 4985 ndp = fpl->ndp; 4986 cnp = fpl->cnp; 4987 4988 cache_fpl_checkpoint(fpl, &fpl->snd); 4989 4990 fpl->dvp = dvp; 4991 fpl->dvp_seqc = vn_seqc_read_any(fpl->dvp); 4992 if (seqc_in_modify(fpl->dvp_seqc)) { 4993 cache_fpl_aborted(fpl); 4994 goto out; 4995 } 4996 mp = atomic_load_ptr(&dvp->v_mount); 4997 if (__predict_false(mp == NULL || !cache_fplookup_mp_supported(mp))) { 4998 cache_fpl_aborted(fpl); 4999 goto out; 5000 } 5001 5002 VNPASS(cache_fplookup_vnode_supported(fpl->dvp), fpl->dvp); 5003 5004 error = cache_fplookup_preparse(fpl); 5005 if (__predict_false(cache_fpl_terminated(fpl))) { 5006 goto out; 5007 } 5008 5009 for (;;) { 5010 error = cache_fplookup_parse(fpl); 5011 if (__predict_false(error != 0)) { 5012 break; 5013 } 5014 5015 VNPASS(cache_fplookup_vnode_supported(fpl->dvp), fpl->dvp); 5016 5017 error = VOP_FPLOOKUP_VEXEC(fpl->dvp, cnp->cn_cred); 5018 if (__predict_false(error != 0)) { 5019 error = cache_fplookup_failed_vexec(fpl, error); 5020 break; 5021 } 5022 5023 error = cache_fplookup_next(fpl); 5024 if (__predict_false(cache_fpl_terminated(fpl))) { 5025 break; 5026 } 5027 5028 VNPASS(!seqc_in_modify(fpl->tvp_seqc), fpl->tvp); 5029 5030 if (cache_fpl_islastcn(ndp)) { 5031 error = cache_fplookup_final(fpl); 5032 break; 5033 } 5034 5035 if (!vn_seqc_consistent(fpl->dvp, fpl->dvp_seqc)) { 5036 error = cache_fpl_aborted(fpl); 5037 break; 5038 } 5039 5040 fpl->dvp = fpl->tvp; 5041 fpl->dvp_seqc = fpl->tvp_seqc; 5042 5043 cache_fplookup_parse_advance(fpl); 5044 cache_fpl_checkpoint(fpl, &fpl->snd); 5045 } 5046 out: 5047 switch (fpl->status) { 5048 case CACHE_FPL_STATUS_UNSET: 5049 __assert_unreachable(); 5050 break; 5051 case CACHE_FPL_STATUS_PARTIAL: 5052 cache_fpl_smr_assert_entered(fpl); 5053 return (cache_fplookup_partial_setup(fpl)); 5054 case CACHE_FPL_STATUS_ABORTED: 5055 if (fpl->in_smr) 5056 cache_fpl_smr_exit(fpl); 5057 return (CACHE_FPL_FAILED); 5058 case CACHE_FPL_STATUS_HANDLED: 5059 MPASS(error != CACHE_FPL_FAILED); 5060 cache_fpl_smr_assert_not_entered(fpl); 5061 /* 5062 * A common error is ENOENT. 5063 */ 5064 if (error != 0) { 5065 ndp->ni_dvp = NULL; 5066 ndp->ni_vp = NULL; 5067 cache_fpl_cleanup_cnp(cnp); 5068 return (error); 5069 } 5070 ndp->ni_dvp = fpl->dvp; 5071 ndp->ni_vp = fpl->tvp; 5072 if (cnp->cn_flags & SAVENAME) 5073 cnp->cn_flags |= HASBUF; 5074 else 5075 cache_fpl_cleanup_cnp(cnp); 5076 return (error); 5077 } 5078 __assert_unreachable(); 5079 } 5080 5081 /* 5082 * Fast path lookup protected with SMR and sequence counters. 5083 * 5084 * Note: all VOP_FPLOOKUP_VEXEC routines have a comment referencing this one. 5085 * 5086 * Filesystems can opt in by setting the MNTK_FPLOOKUP flag and meeting criteria 5087 * outlined below. 5088 * 5089 * Traditional vnode lookup conceptually looks like this: 5090 * 5091 * vn_lock(current); 5092 * for (;;) { 5093 * next = find(); 5094 * vn_lock(next); 5095 * vn_unlock(current); 5096 * current = next; 5097 * if (last) 5098 * break; 5099 * } 5100 * return (current); 5101 * 5102 * Each jump to the next vnode is safe memory-wise and atomic with respect to 5103 * any modifications thanks to holding respective locks. 5104 * 5105 * The same guarantee can be provided with a combination of safe memory 5106 * reclamation and sequence counters instead. If all operations which affect 5107 * the relationship between the current vnode and the one we are looking for 5108 * also modify the counter, we can verify whether all the conditions held as 5109 * we made the jump. This includes things like permissions, mount points etc. 5110 * Counter modification is provided by enclosing relevant places in 5111 * vn_seqc_write_begin()/end() calls. 5112 * 5113 * Thus this translates to: 5114 * 5115 * vfs_smr_enter(); 5116 * dvp_seqc = seqc_read_any(dvp); 5117 * if (seqc_in_modify(dvp_seqc)) // someone is altering the vnode 5118 * abort(); 5119 * for (;;) { 5120 * tvp = find(); 5121 * tvp_seqc = seqc_read_any(tvp); 5122 * if (seqc_in_modify(tvp_seqc)) // someone is altering the target vnode 5123 * abort(); 5124 * if (!seqc_consistent(dvp, dvp_seqc) // someone is altering the vnode 5125 * abort(); 5126 * dvp = tvp; // we know nothing of importance has changed 5127 * dvp_seqc = tvp_seqc; // store the counter for the tvp iteration 5128 * if (last) 5129 * break; 5130 * } 5131 * vget(); // secure the vnode 5132 * if (!seqc_consistent(tvp, tvp_seqc) // final check 5133 * abort(); 5134 * // at this point we know nothing has changed for any parent<->child pair 5135 * // as they were crossed during the lookup, meaning we matched the guarantee 5136 * // of the locked variant 5137 * return (tvp); 5138 * 5139 * The API contract for VOP_FPLOOKUP_VEXEC routines is as follows: 5140 * - they are called while within vfs_smr protection which they must never exit 5141 * - EAGAIN can be returned to denote checking could not be performed, it is 5142 * always valid to return it 5143 * - if the sequence counter has not changed the result must be valid 5144 * - if the sequence counter has changed both false positives and false negatives 5145 * are permitted (since the result will be rejected later) 5146 * - for simple cases of unix permission checks vaccess_vexec_smr can be used 5147 * 5148 * Caveats to watch out for: 5149 * - vnodes are passed unlocked and unreferenced with nothing stopping 5150 * VOP_RECLAIM, in turn meaning that ->v_data can become NULL. It is advised 5151 * to use atomic_load_ptr to fetch it. 5152 * - the aforementioned object can also get freed, meaning absent other means it 5153 * should be protected with vfs_smr 5154 * - either safely checking permissions as they are modified or guaranteeing 5155 * their stability is left to the routine 5156 */ 5157 int 5158 cache_fplookup(struct nameidata *ndp, enum cache_fpl_status *status, 5159 struct pwd **pwdp) 5160 { 5161 struct cache_fpl fpl; 5162 struct pwd *pwd; 5163 struct vnode *dvp; 5164 struct componentname *cnp; 5165 struct nameidata_saved orig; 5166 int error; 5167 5168 MPASS(ndp->ni_lcf == 0); 5169 5170 fpl.status = CACHE_FPL_STATUS_UNSET; 5171 fpl.ndp = ndp; 5172 fpl.cnp = &ndp->ni_cnd; 5173 MPASS(curthread == fpl.cnp->cn_thread); 5174 KASSERT ((fpl.cnp->cn_flags & CACHE_FPL_INTERNAL_CN_FLAGS) == 0, 5175 ("%s: internal flags found in cn_flags %" PRIx64, __func__, 5176 fpl.cnp->cn_flags)); 5177 5178 if ((fpl.cnp->cn_flags & SAVESTART) != 0) 5179 MPASS(fpl.cnp->cn_nameiop != LOOKUP); 5180 5181 if (!cache_can_fplookup(&fpl)) { 5182 SDT_PROBE3(vfs, fplookup, lookup, done, ndp, fpl.line, fpl.status); 5183 *status = fpl.status; 5184 return (EOPNOTSUPP); 5185 } 5186 5187 cache_fpl_checkpoint(&fpl, &orig); 5188 5189 cache_fpl_smr_enter_initial(&fpl); 5190 fpl.fsearch = false; 5191 pwd = pwd_get_smr(); 5192 fpl.pwd = pwd; 5193 ndp->ni_rootdir = pwd->pwd_rdir; 5194 ndp->ni_topdir = pwd->pwd_jdir; 5195 5196 cnp = fpl.cnp; 5197 cnp->cn_nameptr = cnp->cn_pnbuf; 5198 if (cnp->cn_pnbuf[0] == '/') { 5199 dvp = cache_fpl_handle_root(&fpl); 5200 ndp->ni_resflags |= NIRES_ABS; 5201 } else { 5202 if (ndp->ni_dirfd == AT_FDCWD) { 5203 dvp = pwd->pwd_cdir; 5204 } else { 5205 error = cache_fplookup_dirfd(&fpl, &dvp); 5206 if (__predict_false(error != 0)) { 5207 goto out; 5208 } 5209 } 5210 } 5211 5212 SDT_PROBE4(vfs, namei, lookup, entry, dvp, cnp->cn_pnbuf, cnp->cn_flags, true); 5213 5214 error = cache_fplookup_impl(dvp, &fpl); 5215 out: 5216 cache_fpl_smr_assert_not_entered(&fpl); 5217 SDT_PROBE3(vfs, fplookup, lookup, done, ndp, fpl.line, fpl.status); 5218 5219 *status = fpl.status; 5220 switch (fpl.status) { 5221 case CACHE_FPL_STATUS_UNSET: 5222 __assert_unreachable(); 5223 break; 5224 case CACHE_FPL_STATUS_HANDLED: 5225 if (error != 0) 5226 MPASS(ndp->ni_vp == NULL); 5227 SDT_PROBE3(vfs, namei, lookup, return, error, ndp->ni_vp, true); 5228 break; 5229 case CACHE_FPL_STATUS_PARTIAL: 5230 *pwdp = fpl.pwd; 5231 /* 5232 * Status restored by cache_fplookup_partial_setup. 5233 */ 5234 break; 5235 case CACHE_FPL_STATUS_ABORTED: 5236 cache_fpl_restore_abort(&fpl, &orig); 5237 break; 5238 } 5239 return (error); 5240 } 5241