1 /*- 2 * Copyright (c) 1989, 1993, 1995 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Poul-Henning Kamp of the FreeBSD Project. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 4. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * @(#)vfs_cache.c 8.5 (Berkeley) 3/22/95 33 */ 34 35 #include <sys/cdefs.h> 36 __FBSDID("$FreeBSD$"); 37 38 #include "opt_kdtrace.h" 39 #include "opt_ktrace.h" 40 41 #include <sys/param.h> 42 #include <sys/filedesc.h> 43 #include <sys/fnv_hash.h> 44 #include <sys/kernel.h> 45 #include <sys/lock.h> 46 #include <sys/malloc.h> 47 #include <sys/mount.h> 48 #include <sys/namei.h> 49 #include <sys/proc.h> 50 #include <sys/rwlock.h> 51 #include <sys/sdt.h> 52 #include <sys/syscallsubr.h> 53 #include <sys/sysctl.h> 54 #include <sys/sysproto.h> 55 #include <sys/systm.h> 56 #include <sys/vnode.h> 57 #ifdef KTRACE 58 #include <sys/ktrace.h> 59 #endif 60 61 #include <vm/uma.h> 62 63 SDT_PROVIDER_DECLARE(vfs); 64 SDT_PROBE_DEFINE3(vfs, namecache, enter, done, done, "struct vnode *", "char *", 65 "struct vnode *"); 66 SDT_PROBE_DEFINE2(vfs, namecache, enter_negative, done, done, "struct vnode *", 67 "char *"); 68 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, entry, entry, "struct vnode *"); 69 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, hit, hit, "struct vnode *", 70 "struct char *", "struct vnode *"); 71 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, miss, miss, "struct vnode *"); 72 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, return, return, "int", 73 "struct vnode *", "struct char *"); 74 SDT_PROBE_DEFINE3(vfs, namecache, lookup, hit, hit, "struct vnode *", "char *", 75 "struct vnode *"); 76 SDT_PROBE_DEFINE2(vfs, namecache, lookup, hit_negative, hit-negative, 77 "struct vnode *", "char *"); 78 SDT_PROBE_DEFINE2(vfs, namecache, lookup, miss, miss, "struct vnode *", 79 "char *"); 80 SDT_PROBE_DEFINE1(vfs, namecache, purge, done, done, "struct vnode *"); 81 SDT_PROBE_DEFINE1(vfs, namecache, purge_negative, done, done, "struct vnode *"); 82 SDT_PROBE_DEFINE1(vfs, namecache, purgevfs, done, done, "struct mount *"); 83 SDT_PROBE_DEFINE3(vfs, namecache, zap, done, done, "struct vnode *", "char *", 84 "struct vnode *"); 85 SDT_PROBE_DEFINE2(vfs, namecache, zap_negative, done, done, "struct vnode *", 86 "char *"); 87 88 /* 89 * This structure describes the elements in the cache of recent 90 * names looked up by namei. 91 */ 92 93 struct namecache { 94 LIST_ENTRY(namecache) nc_hash; /* hash chain */ 95 LIST_ENTRY(namecache) nc_src; /* source vnode list */ 96 TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */ 97 struct vnode *nc_dvp; /* vnode of parent of name */ 98 struct vnode *nc_vp; /* vnode the name refers to */ 99 u_char nc_flag; /* flag bits */ 100 u_char nc_nlen; /* length of name */ 101 char nc_name[0]; /* segment name + nul */ 102 }; 103 104 /* 105 * Name caching works as follows: 106 * 107 * Names found by directory scans are retained in a cache 108 * for future reference. It is managed LRU, so frequently 109 * used names will hang around. Cache is indexed by hash value 110 * obtained from (vp, name) where vp refers to the directory 111 * containing name. 112 * 113 * If it is a "negative" entry, (i.e. for a name that is known NOT to 114 * exist) the vnode pointer will be NULL. 115 * 116 * Upon reaching the last segment of a path, if the reference 117 * is for DELETE, or NOCACHE is set (rewrite), and the 118 * name is located in the cache, it will be dropped. 119 */ 120 121 /* 122 * Structures associated with name cacheing. 123 */ 124 #define NCHHASH(hash) \ 125 (&nchashtbl[(hash) & nchash]) 126 static LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */ 127 static TAILQ_HEAD(, namecache) ncneg; /* Hash Table */ 128 static u_long nchash; /* size of hash table */ 129 SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, 130 "Size of namecache hash table"); 131 static u_long ncnegfactor = 16; /* ratio of negative entries */ 132 /* _debug sysctl left for backward compatibility */ 133 SYSCTL_ULONG(_debug, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, ""); 134 SYSCTL_ULONG(_vfs, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, 135 "Ratio of negative namecache entries"); 136 static u_long numneg; /* number of negative entries allocated */ 137 SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, 138 "Number of negative entries in namecache"); 139 static u_long numcache; /* number of cache entries allocated */ 140 SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, 141 "Number of namecache entries"); 142 static u_long numcachehv; /* number of cache entries with vnodes held */ 143 SYSCTL_ULONG(_debug, OID_AUTO, numcachehv, CTLFLAG_RD, &numcachehv, 0, 144 "Number of namecache entries with vnodes held"); 145 static u_int ncsizefactor = 2; 146 SYSCTL_UINT(_vfs, OID_AUTO, ncsizefactor, CTLFLAG_RW, &ncsizefactor, 0, 147 "Size factor for namecache"); 148 149 struct nchstats nchstats; /* cache effectiveness statistics */ 150 151 static struct rwlock cache_lock; 152 RW_SYSINIT(vfscache, &cache_lock, "Name Cache"); 153 154 #define CACHE_UPGRADE_LOCK() rw_try_upgrade(&cache_lock) 155 #define CACHE_RLOCK() rw_rlock(&cache_lock) 156 #define CACHE_RUNLOCK() rw_runlock(&cache_lock) 157 #define CACHE_WLOCK() rw_wlock(&cache_lock) 158 #define CACHE_WUNLOCK() rw_wunlock(&cache_lock) 159 160 /* 161 * UMA zones for the VFS cache. 162 * 163 * The small cache is used for entries with short names, which are the 164 * most common. The large cache is used for entries which are too big to 165 * fit in the small cache. 166 */ 167 static uma_zone_t cache_zone_small; 168 static uma_zone_t cache_zone_large; 169 170 #define CACHE_PATH_CUTOFF 35 171 #define CACHE_ZONE_SMALL (sizeof(struct namecache) + CACHE_PATH_CUTOFF \ 172 + 1) 173 #define CACHE_ZONE_LARGE (sizeof(struct namecache) + NAME_MAX + 1) 174 175 #define cache_alloc(len) uma_zalloc(((len) <= CACHE_PATH_CUTOFF) ? \ 176 cache_zone_small : cache_zone_large, M_WAITOK) 177 #define cache_free(ncp) do { \ 178 if (ncp != NULL) \ 179 uma_zfree(((ncp)->nc_nlen <= CACHE_PATH_CUTOFF) ? \ 180 cache_zone_small : cache_zone_large, (ncp)); \ 181 } while (0) 182 183 static int doingcache = 1; /* 1 => enable the cache */ 184 SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0, 185 "VFS namecache enabled"); 186 187 /* Export size information to userland */ 188 SYSCTL_INT(_debug_sizeof, OID_AUTO, namecache, CTLFLAG_RD, 0, 189 sizeof(struct namecache), ""); 190 191 /* 192 * The new name cache statistics 193 */ 194 static SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, "Name cache statistics"); 195 #define STATNODE(mode, name, var) \ 196 SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, mode, var, 0, ""); 197 STATNODE(CTLFLAG_RD, numneg, &numneg); 198 STATNODE(CTLFLAG_RD, numcache, &numcache); 199 static u_long numcalls; STATNODE(CTLFLAG_RD, numcalls, &numcalls); 200 static u_long dothits; STATNODE(CTLFLAG_RD, dothits, &dothits); 201 static u_long dotdothits; STATNODE(CTLFLAG_RD, dotdothits, &dotdothits); 202 static u_long numchecks; STATNODE(CTLFLAG_RD, numchecks, &numchecks); 203 static u_long nummiss; STATNODE(CTLFLAG_RD, nummiss, &nummiss); 204 static u_long nummisszap; STATNODE(CTLFLAG_RD, nummisszap, &nummisszap); 205 static u_long numposzaps; STATNODE(CTLFLAG_RD, numposzaps, &numposzaps); 206 static u_long numposhits; STATNODE(CTLFLAG_RD, numposhits, &numposhits); 207 static u_long numnegzaps; STATNODE(CTLFLAG_RD, numnegzaps, &numnegzaps); 208 static u_long numneghits; STATNODE(CTLFLAG_RD, numneghits, &numneghits); 209 static u_long numupgrades; STATNODE(CTLFLAG_RD, numupgrades, &numupgrades); 210 211 SYSCTL_OPAQUE(_vfs_cache, OID_AUTO, nchstats, CTLFLAG_RD | CTLFLAG_MPSAFE, 212 &nchstats, sizeof(nchstats), "LU", "VFS cache effectiveness statistics"); 213 214 215 216 static void cache_zap(struct namecache *ncp); 217 static int vn_vptocnp_locked(struct vnode **vp, struct ucred *cred, char *buf, 218 u_int *buflen); 219 static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 220 char *buf, char **retbuf, u_int buflen); 221 222 static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); 223 224 /* 225 * Flags in namecache.nc_flag 226 */ 227 #define NCF_WHITE 0x01 228 #define NCF_ISDOTDOT 0x02 229 230 #ifdef DIAGNOSTIC 231 /* 232 * Grab an atomic snapshot of the name cache hash chain lengths 233 */ 234 SYSCTL_NODE(_debug, OID_AUTO, hashstat, CTLFLAG_RW, NULL, "hash table stats"); 235 236 static int 237 sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS) 238 { 239 int error; 240 struct nchashhead *ncpp; 241 struct namecache *ncp; 242 int n_nchash; 243 int count; 244 245 n_nchash = nchash + 1; /* nchash is max index, not count */ 246 if (!req->oldptr) 247 return SYSCTL_OUT(req, 0, n_nchash * sizeof(int)); 248 249 /* Scan hash tables for applicable entries */ 250 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { 251 CACHE_RLOCK(); 252 count = 0; 253 LIST_FOREACH(ncp, ncpp, nc_hash) { 254 count++; 255 } 256 CACHE_RUNLOCK(); 257 error = SYSCTL_OUT(req, &count, sizeof(count)); 258 if (error) 259 return (error); 260 } 261 return (0); 262 } 263 SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD| 264 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_rawnchash, "S,int", 265 "nchash chain lengths"); 266 267 static int 268 sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS) 269 { 270 int error; 271 struct nchashhead *ncpp; 272 struct namecache *ncp; 273 int n_nchash; 274 int count, maxlength, used, pct; 275 276 if (!req->oldptr) 277 return SYSCTL_OUT(req, 0, 4 * sizeof(int)); 278 279 n_nchash = nchash + 1; /* nchash is max index, not count */ 280 used = 0; 281 maxlength = 0; 282 283 /* Scan hash tables for applicable entries */ 284 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { 285 count = 0; 286 CACHE_RLOCK(); 287 LIST_FOREACH(ncp, ncpp, nc_hash) { 288 count++; 289 } 290 CACHE_RUNLOCK(); 291 if (count) 292 used++; 293 if (maxlength < count) 294 maxlength = count; 295 } 296 n_nchash = nchash + 1; 297 pct = (used * 100 * 100) / n_nchash; 298 error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash)); 299 if (error) 300 return (error); 301 error = SYSCTL_OUT(req, &used, sizeof(used)); 302 if (error) 303 return (error); 304 error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength)); 305 if (error) 306 return (error); 307 error = SYSCTL_OUT(req, &pct, sizeof(pct)); 308 if (error) 309 return (error); 310 return (0); 311 } 312 SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD| 313 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_nchash, "I", 314 "nchash chain lengths"); 315 #endif 316 317 /* 318 * cache_zap(): 319 * 320 * Removes a namecache entry from cache, whether it contains an actual 321 * pointer to a vnode or if it is just a negative cache entry. 322 */ 323 static void 324 cache_zap(ncp) 325 struct namecache *ncp; 326 { 327 struct vnode *vp; 328 329 rw_assert(&cache_lock, RA_WLOCKED); 330 CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp, ncp->nc_vp); 331 #ifdef KDTRACE_HOOKS 332 if (ncp->nc_vp != NULL) { 333 SDT_PROBE(vfs, namecache, zap, done, ncp->nc_dvp, 334 ncp->nc_name, ncp->nc_vp, 0, 0); 335 } else { 336 SDT_PROBE(vfs, namecache, zap_negative, done, ncp->nc_dvp, 337 ncp->nc_name, 0, 0, 0); 338 } 339 #endif 340 vp = NULL; 341 LIST_REMOVE(ncp, nc_hash); 342 if (ncp->nc_flag & NCF_ISDOTDOT) { 343 if (ncp == ncp->nc_dvp->v_cache_dd) 344 ncp->nc_dvp->v_cache_dd = NULL; 345 } else { 346 LIST_REMOVE(ncp, nc_src); 347 if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) { 348 vp = ncp->nc_dvp; 349 numcachehv--; 350 } 351 } 352 if (ncp->nc_vp) { 353 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst); 354 if (ncp == ncp->nc_vp->v_cache_dd) 355 ncp->nc_vp->v_cache_dd = NULL; 356 } else { 357 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 358 numneg--; 359 } 360 numcache--; 361 cache_free(ncp); 362 if (vp) 363 vdrop(vp); 364 } 365 366 /* 367 * Lookup an entry in the cache 368 * 369 * Lookup is called with dvp pointing to the directory to search, 370 * cnp pointing to the name of the entry being sought. If the lookup 371 * succeeds, the vnode is returned in *vpp, and a status of -1 is 372 * returned. If the lookup determines that the name does not exist 373 * (negative cacheing), a status of ENOENT is returned. If the lookup 374 * fails, a status of zero is returned. If the directory vnode is 375 * recycled out from under us due to a forced unmount, a status of 376 * ENOENT is returned. 377 * 378 * vpp is locked and ref'd on return. If we're looking up DOTDOT, dvp is 379 * unlocked. If we're looking up . an extra ref is taken, but the lock is 380 * not recursively acquired. 381 */ 382 383 int 384 cache_lookup(dvp, vpp, cnp) 385 struct vnode *dvp; 386 struct vnode **vpp; 387 struct componentname *cnp; 388 { 389 struct namecache *ncp; 390 uint32_t hash; 391 int error, ltype, wlocked; 392 393 if (!doingcache) { 394 cnp->cn_flags &= ~MAKEENTRY; 395 return (0); 396 } 397 retry: 398 CACHE_RLOCK(); 399 wlocked = 0; 400 numcalls++; 401 error = 0; 402 403 retry_wlocked: 404 if (cnp->cn_nameptr[0] == '.') { 405 if (cnp->cn_namelen == 1) { 406 *vpp = dvp; 407 CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .", 408 dvp, cnp->cn_nameptr); 409 dothits++; 410 SDT_PROBE(vfs, namecache, lookup, hit, dvp, ".", 411 *vpp, 0, 0); 412 goto success; 413 } 414 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 415 dotdothits++; 416 if (dvp->v_cache_dd == NULL) { 417 SDT_PROBE(vfs, namecache, lookup, miss, dvp, 418 "..", NULL, 0, 0); 419 goto unlock; 420 } 421 if ((cnp->cn_flags & MAKEENTRY) == 0) { 422 if (!wlocked && !CACHE_UPGRADE_LOCK()) 423 goto wlock; 424 if (dvp->v_cache_dd->nc_flag & NCF_ISDOTDOT) 425 cache_zap(dvp->v_cache_dd); 426 dvp->v_cache_dd = NULL; 427 CACHE_WUNLOCK(); 428 return (0); 429 } 430 if (dvp->v_cache_dd->nc_flag & NCF_ISDOTDOT) 431 *vpp = dvp->v_cache_dd->nc_vp; 432 else 433 *vpp = dvp->v_cache_dd->nc_dvp; 434 /* Return failure if negative entry was found. */ 435 if (*vpp == NULL) { 436 ncp = dvp->v_cache_dd; 437 goto negative_success; 438 } 439 CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..", 440 dvp, cnp->cn_nameptr, *vpp); 441 SDT_PROBE(vfs, namecache, lookup, hit, dvp, "..", 442 *vpp, 0, 0); 443 goto success; 444 } 445 } 446 447 hash = fnv_32_buf(cnp->cn_nameptr, cnp->cn_namelen, FNV1_32_INIT); 448 hash = fnv_32_buf(&dvp, sizeof(dvp), hash); 449 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 450 numchecks++; 451 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 452 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 453 break; 454 } 455 456 /* We failed to find an entry */ 457 if (ncp == NULL) { 458 SDT_PROBE(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr, 459 NULL, 0, 0); 460 if ((cnp->cn_flags & MAKEENTRY) == 0) { 461 nummisszap++; 462 } else { 463 nummiss++; 464 } 465 nchstats.ncs_miss++; 466 goto unlock; 467 } 468 469 /* We don't want to have an entry, so dump it */ 470 if ((cnp->cn_flags & MAKEENTRY) == 0) { 471 numposzaps++; 472 nchstats.ncs_badhits++; 473 if (!wlocked && !CACHE_UPGRADE_LOCK()) 474 goto wlock; 475 cache_zap(ncp); 476 CACHE_WUNLOCK(); 477 return (0); 478 } 479 480 /* We found a "positive" match, return the vnode */ 481 if (ncp->nc_vp) { 482 numposhits++; 483 nchstats.ncs_goodhits++; 484 *vpp = ncp->nc_vp; 485 CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p", 486 dvp, cnp->cn_nameptr, *vpp, ncp); 487 SDT_PROBE(vfs, namecache, lookup, hit, dvp, ncp->nc_name, 488 *vpp, 0, 0); 489 goto success; 490 } 491 492 negative_success: 493 /* We found a negative match, and want to create it, so purge */ 494 if (cnp->cn_nameiop == CREATE) { 495 numnegzaps++; 496 nchstats.ncs_badhits++; 497 if (!wlocked && !CACHE_UPGRADE_LOCK()) 498 goto wlock; 499 cache_zap(ncp); 500 CACHE_WUNLOCK(); 501 return (0); 502 } 503 504 if (!wlocked && !CACHE_UPGRADE_LOCK()) 505 goto wlock; 506 numneghits++; 507 /* 508 * We found a "negative" match, so we shift it to the end of 509 * the "negative" cache entries queue to satisfy LRU. Also, 510 * check to see if the entry is a whiteout; indicate this to 511 * the componentname, if so. 512 */ 513 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 514 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 515 nchstats.ncs_neghits++; 516 if (ncp->nc_flag & NCF_WHITE) 517 cnp->cn_flags |= ISWHITEOUT; 518 SDT_PROBE(vfs, namecache, lookup, hit_negative, dvp, ncp->nc_name, 519 0, 0, 0); 520 CACHE_WUNLOCK(); 521 return (ENOENT); 522 523 wlock: 524 /* 525 * We need to update the cache after our lookup, so upgrade to 526 * a write lock and retry the operation. 527 */ 528 CACHE_RUNLOCK(); 529 CACHE_WLOCK(); 530 numupgrades++; 531 wlocked = 1; 532 goto retry_wlocked; 533 534 success: 535 /* 536 * On success we return a locked and ref'd vnode as per the lookup 537 * protocol. 538 */ 539 if (dvp == *vpp) { /* lookup on "." */ 540 VREF(*vpp); 541 if (wlocked) 542 CACHE_WUNLOCK(); 543 else 544 CACHE_RUNLOCK(); 545 /* 546 * When we lookup "." we still can be asked to lock it 547 * differently... 548 */ 549 ltype = cnp->cn_lkflags & LK_TYPE_MASK; 550 if (ltype != VOP_ISLOCKED(*vpp)) { 551 if (ltype == LK_EXCLUSIVE) { 552 vn_lock(*vpp, LK_UPGRADE | LK_RETRY); 553 if ((*vpp)->v_iflag & VI_DOOMED) { 554 /* forced unmount */ 555 vrele(*vpp); 556 *vpp = NULL; 557 return (ENOENT); 558 } 559 } else 560 vn_lock(*vpp, LK_DOWNGRADE | LK_RETRY); 561 } 562 return (-1); 563 } 564 ltype = 0; /* silence gcc warning */ 565 if (cnp->cn_flags & ISDOTDOT) { 566 ltype = VOP_ISLOCKED(dvp); 567 VOP_UNLOCK(dvp, 0); 568 } 569 VI_LOCK(*vpp); 570 if (wlocked) 571 CACHE_WUNLOCK(); 572 else 573 CACHE_RUNLOCK(); 574 error = vget(*vpp, cnp->cn_lkflags | LK_INTERLOCK, cnp->cn_thread); 575 if (cnp->cn_flags & ISDOTDOT) { 576 vn_lock(dvp, ltype | LK_RETRY); 577 if (dvp->v_iflag & VI_DOOMED) { 578 if (error == 0) 579 vput(*vpp); 580 *vpp = NULL; 581 return (ENOENT); 582 } 583 } 584 if (error) { 585 *vpp = NULL; 586 goto retry; 587 } 588 if ((cnp->cn_flags & ISLASTCN) && 589 (cnp->cn_lkflags & LK_TYPE_MASK) == LK_EXCLUSIVE) { 590 ASSERT_VOP_ELOCKED(*vpp, "cache_lookup"); 591 } 592 return (-1); 593 594 unlock: 595 if (wlocked) 596 CACHE_WUNLOCK(); 597 else 598 CACHE_RUNLOCK(); 599 return (0); 600 } 601 602 /* 603 * Add an entry to the cache. 604 */ 605 void 606 cache_enter(dvp, vp, cnp) 607 struct vnode *dvp; 608 struct vnode *vp; 609 struct componentname *cnp; 610 { 611 struct namecache *ncp, *n2; 612 struct nchashhead *ncpp; 613 uint32_t hash; 614 int flag; 615 int hold; 616 int zap; 617 int len; 618 619 CTR3(KTR_VFS, "cache_enter(%p, %p, %s)", dvp, vp, cnp->cn_nameptr); 620 VNASSERT(vp == NULL || (vp->v_iflag & VI_DOOMED) == 0, vp, 621 ("cache_enter: Adding a doomed vnode")); 622 VNASSERT(dvp == NULL || (dvp->v_iflag & VI_DOOMED) == 0, dvp, 623 ("cache_enter: Doomed vnode used as src")); 624 625 if (!doingcache) 626 return; 627 628 /* 629 * Avoid blowout in namecache entries. 630 */ 631 if (numcache >= desiredvnodes * ncsizefactor) 632 return; 633 634 flag = 0; 635 if (cnp->cn_nameptr[0] == '.') { 636 if (cnp->cn_namelen == 1) 637 return; 638 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 639 CACHE_WLOCK(); 640 /* 641 * If dotdot entry already exists, just retarget it 642 * to new parent vnode, otherwise continue with new 643 * namecache entry allocation. 644 */ 645 if ((ncp = dvp->v_cache_dd) != NULL && 646 ncp->nc_flag & NCF_ISDOTDOT) { 647 KASSERT(ncp->nc_dvp == dvp, 648 ("wrong isdotdot parent")); 649 if (ncp->nc_vp != NULL) 650 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, 651 ncp, nc_dst); 652 else 653 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 654 if (vp != NULL) 655 TAILQ_INSERT_HEAD(&vp->v_cache_dst, 656 ncp, nc_dst); 657 else 658 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 659 ncp->nc_vp = vp; 660 CACHE_WUNLOCK(); 661 return; 662 } 663 dvp->v_cache_dd = NULL; 664 SDT_PROBE(vfs, namecache, enter, done, dvp, "..", vp, 665 0, 0); 666 CACHE_WUNLOCK(); 667 flag = NCF_ISDOTDOT; 668 } 669 } 670 671 hold = 0; 672 zap = 0; 673 674 /* 675 * Calculate the hash key and setup as much of the new 676 * namecache entry as possible before acquiring the lock. 677 */ 678 ncp = cache_alloc(cnp->cn_namelen); 679 ncp->nc_vp = vp; 680 ncp->nc_dvp = dvp; 681 ncp->nc_flag = flag; 682 len = ncp->nc_nlen = cnp->cn_namelen; 683 hash = fnv_32_buf(cnp->cn_nameptr, len, FNV1_32_INIT); 684 strlcpy(ncp->nc_name, cnp->cn_nameptr, len + 1); 685 hash = fnv_32_buf(&dvp, sizeof(dvp), hash); 686 CACHE_WLOCK(); 687 688 /* 689 * See if this vnode or negative entry is already in the cache 690 * with this name. This can happen with concurrent lookups of 691 * the same path name. 692 */ 693 ncpp = NCHHASH(hash); 694 LIST_FOREACH(n2, ncpp, nc_hash) { 695 if (n2->nc_dvp == dvp && 696 n2->nc_nlen == cnp->cn_namelen && 697 !bcmp(n2->nc_name, cnp->cn_nameptr, n2->nc_nlen)) { 698 CACHE_WUNLOCK(); 699 cache_free(ncp); 700 return; 701 } 702 } 703 704 if (flag == NCF_ISDOTDOT) { 705 /* 706 * See if we are trying to add .. entry, but some other lookup 707 * has populated v_cache_dd pointer already. 708 */ 709 if (dvp->v_cache_dd != NULL) { 710 CACHE_WUNLOCK(); 711 cache_free(ncp); 712 return; 713 } 714 KASSERT(vp == NULL || vp->v_type == VDIR, 715 ("wrong vnode type %p", vp)); 716 dvp->v_cache_dd = ncp; 717 } 718 719 numcache++; 720 if (!vp) { 721 numneg++; 722 if (cnp->cn_flags & ISWHITEOUT) 723 ncp->nc_flag |= NCF_WHITE; 724 } else if (vp->v_type == VDIR) { 725 if (flag != NCF_ISDOTDOT) { 726 if ((n2 = vp->v_cache_dd) != NULL && 727 (n2->nc_flag & NCF_ISDOTDOT) != 0) 728 cache_zap(n2); 729 vp->v_cache_dd = ncp; 730 } 731 } else { 732 vp->v_cache_dd = NULL; 733 } 734 735 /* 736 * Insert the new namecache entry into the appropriate chain 737 * within the cache entries table. 738 */ 739 LIST_INSERT_HEAD(ncpp, ncp, nc_hash); 740 if (flag != NCF_ISDOTDOT) { 741 if (LIST_EMPTY(&dvp->v_cache_src)) { 742 hold = 1; 743 numcachehv++; 744 } 745 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); 746 } 747 748 /* 749 * If the entry is "negative", we place it into the 750 * "negative" cache queue, otherwise, we place it into the 751 * destination vnode's cache entries queue. 752 */ 753 if (vp) { 754 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); 755 SDT_PROBE(vfs, namecache, enter, done, dvp, ncp->nc_name, vp, 756 0, 0); 757 } else { 758 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 759 SDT_PROBE(vfs, namecache, enter_negative, done, dvp, 760 ncp->nc_name, 0, 0, 0); 761 } 762 if (numneg * ncnegfactor > numcache) { 763 ncp = TAILQ_FIRST(&ncneg); 764 zap = 1; 765 } 766 if (hold) 767 vhold(dvp); 768 if (zap) 769 cache_zap(ncp); 770 CACHE_WUNLOCK(); 771 } 772 773 /* 774 * Name cache initialization, from vfs_init() when we are booting 775 */ 776 static void 777 nchinit(void *dummy __unused) 778 { 779 780 TAILQ_INIT(&ncneg); 781 782 cache_zone_small = uma_zcreate("S VFS Cache", CACHE_ZONE_SMALL, NULL, 783 NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 784 cache_zone_large = uma_zcreate("L VFS Cache", CACHE_ZONE_LARGE, NULL, 785 NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 786 787 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash); 788 } 789 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL); 790 791 792 /* 793 * Invalidate all entries to a particular vnode. 794 */ 795 void 796 cache_purge(vp) 797 struct vnode *vp; 798 { 799 800 CTR1(KTR_VFS, "cache_purge(%p)", vp); 801 SDT_PROBE(vfs, namecache, purge, done, vp, 0, 0, 0, 0); 802 CACHE_WLOCK(); 803 while (!LIST_EMPTY(&vp->v_cache_src)) 804 cache_zap(LIST_FIRST(&vp->v_cache_src)); 805 while (!TAILQ_EMPTY(&vp->v_cache_dst)) 806 cache_zap(TAILQ_FIRST(&vp->v_cache_dst)); 807 if (vp->v_cache_dd != NULL) { 808 KASSERT(vp->v_cache_dd->nc_flag & NCF_ISDOTDOT, 809 ("lost dotdot link")); 810 cache_zap(vp->v_cache_dd); 811 } 812 KASSERT(vp->v_cache_dd == NULL, ("incomplete purge")); 813 CACHE_WUNLOCK(); 814 } 815 816 /* 817 * Invalidate all negative entries for a particular directory vnode. 818 */ 819 void 820 cache_purge_negative(vp) 821 struct vnode *vp; 822 { 823 struct namecache *cp, *ncp; 824 825 CTR1(KTR_VFS, "cache_purge_negative(%p)", vp); 826 SDT_PROBE(vfs, namecache, purge_negative, done, vp, 0, 0, 0, 0); 827 CACHE_WLOCK(); 828 LIST_FOREACH_SAFE(cp, &vp->v_cache_src, nc_src, ncp) { 829 if (cp->nc_vp == NULL) 830 cache_zap(cp); 831 } 832 CACHE_WUNLOCK(); 833 } 834 835 /* 836 * Flush all entries referencing a particular filesystem. 837 */ 838 void 839 cache_purgevfs(mp) 840 struct mount *mp; 841 { 842 struct nchashhead *ncpp; 843 struct namecache *ncp, *nnp; 844 845 /* Scan hash tables for applicable entries */ 846 SDT_PROBE(vfs, namecache, purgevfs, done, mp, 0, 0, 0, 0); 847 CACHE_WLOCK(); 848 for (ncpp = &nchashtbl[nchash]; ncpp >= nchashtbl; ncpp--) { 849 LIST_FOREACH_SAFE(ncp, ncpp, nc_hash, nnp) { 850 if (ncp->nc_dvp->v_mount == mp) 851 cache_zap(ncp); 852 } 853 } 854 CACHE_WUNLOCK(); 855 } 856 857 /* 858 * Perform canonical checks and cache lookup and pass on to filesystem 859 * through the vop_cachedlookup only if needed. 860 */ 861 862 int 863 vfs_cache_lookup(ap) 864 struct vop_lookup_args /* { 865 struct vnode *a_dvp; 866 struct vnode **a_vpp; 867 struct componentname *a_cnp; 868 } */ *ap; 869 { 870 struct vnode *dvp; 871 int error; 872 struct vnode **vpp = ap->a_vpp; 873 struct componentname *cnp = ap->a_cnp; 874 struct ucred *cred = cnp->cn_cred; 875 int flags = cnp->cn_flags; 876 struct thread *td = cnp->cn_thread; 877 878 *vpp = NULL; 879 dvp = ap->a_dvp; 880 881 if (dvp->v_type != VDIR) 882 return (ENOTDIR); 883 884 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && 885 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 886 return (EROFS); 887 888 error = VOP_ACCESS(dvp, VEXEC, cred, td); 889 if (error) 890 return (error); 891 892 error = cache_lookup(dvp, vpp, cnp); 893 if (error == 0) 894 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); 895 if (error == -1) 896 return (0); 897 return (error); 898 } 899 900 901 #ifndef _SYS_SYSPROTO_H_ 902 struct __getcwd_args { 903 u_char *buf; 904 u_int buflen; 905 }; 906 #endif 907 908 /* 909 * XXX All of these sysctls would probably be more productive dead. 910 */ 911 static int disablecwd; 912 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, 913 "Disable the getcwd syscall"); 914 915 /* Implementation of the getcwd syscall. */ 916 int 917 __getcwd(td, uap) 918 struct thread *td; 919 struct __getcwd_args *uap; 920 { 921 922 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen)); 923 } 924 925 int 926 kern___getcwd(struct thread *td, u_char *buf, enum uio_seg bufseg, u_int buflen) 927 { 928 char *bp, *tmpbuf; 929 struct filedesc *fdp; 930 struct vnode *cdir, *rdir; 931 int error, vfslocked; 932 933 if (disablecwd) 934 return (ENODEV); 935 if (buflen < 2) 936 return (EINVAL); 937 if (buflen > MAXPATHLEN) 938 buflen = MAXPATHLEN; 939 940 tmpbuf = malloc(buflen, M_TEMP, M_WAITOK); 941 fdp = td->td_proc->p_fd; 942 FILEDESC_SLOCK(fdp); 943 cdir = fdp->fd_cdir; 944 VREF(cdir); 945 rdir = fdp->fd_rdir; 946 VREF(rdir); 947 FILEDESC_SUNLOCK(fdp); 948 error = vn_fullpath1(td, cdir, rdir, tmpbuf, &bp, buflen); 949 vfslocked = VFS_LOCK_GIANT(rdir->v_mount); 950 vrele(rdir); 951 VFS_UNLOCK_GIANT(vfslocked); 952 vfslocked = VFS_LOCK_GIANT(cdir->v_mount); 953 vrele(cdir); 954 VFS_UNLOCK_GIANT(vfslocked); 955 956 if (!error) { 957 if (bufseg == UIO_SYSSPACE) 958 bcopy(bp, buf, strlen(bp) + 1); 959 else 960 error = copyout(bp, buf, strlen(bp) + 1); 961 #ifdef KTRACE 962 if (KTRPOINT(curthread, KTR_NAMEI)) 963 ktrnamei(bp); 964 #endif 965 } 966 free(tmpbuf, M_TEMP); 967 return (error); 968 } 969 970 /* 971 * Thus begins the fullpath magic. 972 */ 973 974 #undef STATNODE 975 #define STATNODE(name) \ 976 static u_int name; \ 977 SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, "") 978 979 static int disablefullpath; 980 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0, 981 "Disable the vn_fullpath function"); 982 983 /* These count for kern___getcwd(), too. */ 984 STATNODE(numfullpathcalls); 985 STATNODE(numfullpathfail1); 986 STATNODE(numfullpathfail2); 987 STATNODE(numfullpathfail4); 988 STATNODE(numfullpathfound); 989 990 /* 991 * Retrieve the full filesystem path that correspond to a vnode from the name 992 * cache (if available) 993 */ 994 int 995 vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf) 996 { 997 char *buf; 998 struct filedesc *fdp; 999 struct vnode *rdir; 1000 int error, vfslocked; 1001 1002 if (disablefullpath) 1003 return (ENODEV); 1004 if (vn == NULL) 1005 return (EINVAL); 1006 1007 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 1008 fdp = td->td_proc->p_fd; 1009 FILEDESC_SLOCK(fdp); 1010 rdir = fdp->fd_rdir; 1011 VREF(rdir); 1012 FILEDESC_SUNLOCK(fdp); 1013 error = vn_fullpath1(td, vn, rdir, buf, retbuf, MAXPATHLEN); 1014 vfslocked = VFS_LOCK_GIANT(rdir->v_mount); 1015 vrele(rdir); 1016 VFS_UNLOCK_GIANT(vfslocked); 1017 1018 if (!error) 1019 *freebuf = buf; 1020 else 1021 free(buf, M_TEMP); 1022 return (error); 1023 } 1024 1025 /* 1026 * This function is similar to vn_fullpath, but it attempts to lookup the 1027 * pathname relative to the global root mount point. This is required for the 1028 * auditing sub-system, as audited pathnames must be absolute, relative to the 1029 * global root mount point. 1030 */ 1031 int 1032 vn_fullpath_global(struct thread *td, struct vnode *vn, 1033 char **retbuf, char **freebuf) 1034 { 1035 char *buf; 1036 int error; 1037 1038 if (disablefullpath) 1039 return (ENODEV); 1040 if (vn == NULL) 1041 return (EINVAL); 1042 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 1043 error = vn_fullpath1(td, vn, rootvnode, buf, retbuf, MAXPATHLEN); 1044 if (!error) 1045 *freebuf = buf; 1046 else 1047 free(buf, M_TEMP); 1048 return (error); 1049 } 1050 1051 int 1052 vn_vptocnp(struct vnode **vp, struct ucred *cred, char *buf, u_int *buflen) 1053 { 1054 int error; 1055 1056 CACHE_RLOCK(); 1057 error = vn_vptocnp_locked(vp, cred, buf, buflen); 1058 if (error == 0) { 1059 /* 1060 * vn_vptocnp_locked() dropped hold acquired by 1061 * VOP_VPTOCNP immediately after locking the 1062 * cache. Since we are going to drop the cache rlock, 1063 * re-hold the result. 1064 */ 1065 vhold(*vp); 1066 CACHE_RUNLOCK(); 1067 } 1068 return (error); 1069 } 1070 1071 static int 1072 vn_vptocnp_locked(struct vnode **vp, struct ucred *cred, char *buf, 1073 u_int *buflen) 1074 { 1075 struct vnode *dvp; 1076 struct namecache *ncp; 1077 int error, vfslocked; 1078 1079 TAILQ_FOREACH(ncp, &((*vp)->v_cache_dst), nc_dst) { 1080 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 1081 break; 1082 } 1083 if (ncp != NULL) { 1084 if (*buflen < ncp->nc_nlen) { 1085 CACHE_RUNLOCK(); 1086 numfullpathfail4++; 1087 error = ENOMEM; 1088 SDT_PROBE(vfs, namecache, fullpath, return, error, 1089 vp, NULL, 0, 0); 1090 return (error); 1091 } 1092 *buflen -= ncp->nc_nlen; 1093 memcpy(buf + *buflen, ncp->nc_name, ncp->nc_nlen); 1094 SDT_PROBE(vfs, namecache, fullpath, hit, ncp->nc_dvp, 1095 ncp->nc_name, vp, 0, 0); 1096 *vp = ncp->nc_dvp; 1097 return (0); 1098 } 1099 SDT_PROBE(vfs, namecache, fullpath, miss, vp, 0, 0, 0, 0); 1100 1101 vhold(*vp); 1102 CACHE_RUNLOCK(); 1103 vfslocked = VFS_LOCK_GIANT((*vp)->v_mount); 1104 vn_lock(*vp, LK_SHARED | LK_RETRY); 1105 error = VOP_VPTOCNP(*vp, &dvp, cred, buf, buflen); 1106 VOP_UNLOCK(*vp, 0); 1107 vdrop(*vp); 1108 VFS_UNLOCK_GIANT(vfslocked); 1109 if (error) { 1110 numfullpathfail2++; 1111 SDT_PROBE(vfs, namecache, fullpath, return, error, vp, 1112 NULL, 0, 0); 1113 return (error); 1114 } 1115 1116 *vp = dvp; 1117 CACHE_RLOCK(); 1118 if ((*vp)->v_iflag & VI_DOOMED) { 1119 /* forced unmount */ 1120 CACHE_RUNLOCK(); 1121 vdrop(*vp); 1122 error = ENOENT; 1123 SDT_PROBE(vfs, namecache, fullpath, return, error, vp, 1124 NULL, 0, 0); 1125 return (error); 1126 } 1127 vdrop(*vp); 1128 1129 return (0); 1130 } 1131 1132 /* 1133 * The magic behind kern___getcwd() and vn_fullpath(). 1134 */ 1135 static int 1136 vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 1137 char *buf, char **retbuf, u_int buflen) 1138 { 1139 int error, slash_prefixed; 1140 #ifdef KDTRACE_HOOKS 1141 struct vnode *startvp = vp; 1142 #endif 1143 1144 buflen--; 1145 buf[buflen] = '\0'; 1146 error = 0; 1147 slash_prefixed = 0; 1148 1149 SDT_PROBE(vfs, namecache, fullpath, entry, vp, 0, 0, 0, 0); 1150 numfullpathcalls++; 1151 CACHE_RLOCK(); 1152 if (vp->v_type != VDIR) { 1153 error = vn_vptocnp_locked(&vp, td->td_ucred, buf, &buflen); 1154 if (error) 1155 return (error); 1156 if (buflen == 0) { 1157 CACHE_RUNLOCK(); 1158 return (ENOMEM); 1159 } 1160 buf[--buflen] = '/'; 1161 slash_prefixed = 1; 1162 } 1163 while (vp != rdir && vp != rootvnode) { 1164 if (vp->v_vflag & VV_ROOT) { 1165 if (vp->v_iflag & VI_DOOMED) { /* forced unmount */ 1166 CACHE_RUNLOCK(); 1167 error = ENOENT; 1168 SDT_PROBE(vfs, namecache, fullpath, return, 1169 error, vp, NULL, 0, 0); 1170 break; 1171 } 1172 vp = vp->v_mount->mnt_vnodecovered; 1173 continue; 1174 } 1175 if (vp->v_type != VDIR) { 1176 CACHE_RUNLOCK(); 1177 numfullpathfail1++; 1178 error = ENOTDIR; 1179 SDT_PROBE(vfs, namecache, fullpath, return, 1180 error, vp, NULL, 0, 0); 1181 break; 1182 } 1183 error = vn_vptocnp_locked(&vp, td->td_ucred, buf, &buflen); 1184 if (error) 1185 break; 1186 if (buflen == 0) { 1187 CACHE_RUNLOCK(); 1188 error = ENOMEM; 1189 SDT_PROBE(vfs, namecache, fullpath, return, error, 1190 startvp, NULL, 0, 0); 1191 break; 1192 } 1193 buf[--buflen] = '/'; 1194 slash_prefixed = 1; 1195 } 1196 if (error) 1197 return (error); 1198 if (!slash_prefixed) { 1199 if (buflen == 0) { 1200 CACHE_RUNLOCK(); 1201 numfullpathfail4++; 1202 SDT_PROBE(vfs, namecache, fullpath, return, ENOMEM, 1203 startvp, NULL, 0, 0); 1204 return (ENOMEM); 1205 } 1206 buf[--buflen] = '/'; 1207 } 1208 numfullpathfound++; 1209 CACHE_RUNLOCK(); 1210 1211 SDT_PROBE(vfs, namecache, fullpath, return, 0, startvp, buf + buflen, 1212 0, 0); 1213 *retbuf = buf + buflen; 1214 return (0); 1215 } 1216 1217 int 1218 vn_commname(struct vnode *vp, char *buf, u_int buflen) 1219 { 1220 struct namecache *ncp; 1221 int l; 1222 1223 CACHE_RLOCK(); 1224 TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst) 1225 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 1226 break; 1227 if (ncp == NULL) { 1228 CACHE_RUNLOCK(); 1229 return (ENOENT); 1230 } 1231 l = min(ncp->nc_nlen, buflen - 1); 1232 memcpy(buf, ncp->nc_name, l); 1233 CACHE_RUNLOCK(); 1234 buf[l] = '\0'; 1235 return (0); 1236 } 1237