Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/kern/vfs_cache.c
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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: releng/9.0/sys/kern/vfs_cache.c 225617 2011-09-16 13:58:51Z kmacy $"); 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 SYSCTL_ULONG(_vfs, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, 133 "Ratio of negative namecache entries"); 134 static u_long numneg; /* number of negative entries allocated */ 135 SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, 136 "Number of negative entries in namecache"); 137 static u_long numcache; /* number of cache entries allocated */ 138 SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, 139 "Number of namecache entries"); 140 static u_long numcachehv; /* number of cache entries with vnodes held */ 141 SYSCTL_ULONG(_debug, OID_AUTO, numcachehv, CTLFLAG_RD, &numcachehv, 0, 142 "Number of namecache entries with vnodes held"); 143 static u_int ncsizefactor = 2; 144 SYSCTL_UINT(_vfs, OID_AUTO, ncsizefactor, CTLFLAG_RW, &ncsizefactor, 0, 145 "Size factor for namecache"); 146 147 struct nchstats nchstats; /* cache effectiveness statistics */ 148 149 static struct rwlock cache_lock; 150 RW_SYSINIT(vfscache, &cache_lock, "Name Cache"); 151 152 #define CACHE_UPGRADE_LOCK() rw_try_upgrade(&cache_lock) 153 #define CACHE_RLOCK() rw_rlock(&cache_lock) 154 #define CACHE_RUNLOCK() rw_runlock(&cache_lock) 155 #define CACHE_WLOCK() rw_wlock(&cache_lock) 156 #define CACHE_WUNLOCK() rw_wunlock(&cache_lock) 157 158 /* 159 * UMA zones for the VFS cache. 160 * 161 * The small cache is used for entries with short names, which are the 162 * most common. The large cache is used for entries which are too big to 163 * fit in the small cache. 164 */ 165 static uma_zone_t cache_zone_small; 166 static uma_zone_t cache_zone_large; 167 168 #define CACHE_PATH_CUTOFF 35 169 #define CACHE_ZONE_SMALL (sizeof(struct namecache) + CACHE_PATH_CUTOFF \ 170 + 1) 171 #define CACHE_ZONE_LARGE (sizeof(struct namecache) + NAME_MAX + 1) 172 173 #define cache_alloc(len) uma_zalloc(((len) <= CACHE_PATH_CUTOFF) ? \ 174 cache_zone_small : cache_zone_large, M_WAITOK) 175 #define cache_free(ncp) do { \ 176 if (ncp != NULL) \ 177 uma_zfree(((ncp)->nc_nlen <= CACHE_PATH_CUTOFF) ? \ 178 cache_zone_small : cache_zone_large, (ncp)); \ 179 } while (0) 180 181 static int doingcache = 1; /* 1 => enable the cache */ 182 SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0, 183 "VFS namecache enabled"); 184 185 /* Export size information to userland */ 186 SYSCTL_INT(_debug_sizeof, OID_AUTO, namecache, CTLFLAG_RD, 0, 187 sizeof(struct namecache), "sizeof(struct namecache)"); 188 189 /* 190 * The new name cache statistics 191 */ 192 static SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, 193 "Name cache statistics"); 194 #define STATNODE(mode, name, var, descr) \ 195 SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, mode, var, 0, descr); 196 STATNODE(CTLFLAG_RD, numneg, &numneg, "Number of negative cache entries"); 197 STATNODE(CTLFLAG_RD, numcache, &numcache, "Number of cache entries"); 198 static u_long numcalls; STATNODE(CTLFLAG_RD, numcalls, &numcalls, 199 "Number of cache lookups"); 200 static u_long dothits; STATNODE(CTLFLAG_RD, dothits, &dothits, 201 "Number of '.' hits"); 202 static u_long dotdothits; STATNODE(CTLFLAG_RD, dotdothits, &dotdothits, 203 "Number of '..' hits"); 204 static u_long numchecks; STATNODE(CTLFLAG_RD, numchecks, &numchecks, 205 "Number of checks in lookup"); 206 static u_long nummiss; STATNODE(CTLFLAG_RD, nummiss, &nummiss, 207 "Number of cache misses"); 208 static u_long nummisszap; STATNODE(CTLFLAG_RD, nummisszap, &nummisszap, 209 "Number of cache misses we do not want to cache"); 210 static u_long numposzaps; STATNODE(CTLFLAG_RD, numposzaps, &numposzaps, 211 "Number of cache hits (positive) we do not want to cache"); 212 static u_long numposhits; STATNODE(CTLFLAG_RD, numposhits, &numposhits, 213 "Number of cache hits (positive)"); 214 static u_long numnegzaps; STATNODE(CTLFLAG_RD, numnegzaps, &numnegzaps, 215 "Number of cache hits (negative) we do not want to cache"); 216 static u_long numneghits; STATNODE(CTLFLAG_RD, numneghits, &numneghits, 217 "Number of cache hits (negative)"); 218 static u_long numupgrades; STATNODE(CTLFLAG_RD, numupgrades, &numupgrades, 219 "Number of updates of the cache after lookup (write lock + retry)"); 220 221 SYSCTL_OPAQUE(_vfs_cache, OID_AUTO, nchstats, CTLFLAG_RD | CTLFLAG_MPSAFE, 222 &nchstats, sizeof(nchstats), "LU", 223 "VFS cache effectiveness statistics"); 224 225 226 227 static void cache_zap(struct namecache *ncp); 228 static int vn_vptocnp_locked(struct vnode **vp, struct ucred *cred, char *buf, 229 u_int *buflen); 230 static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 231 char *buf, char **retbuf, u_int buflen); 232 233 static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); 234 235 /* 236 * Flags in namecache.nc_flag 237 */ 238 #define NCF_WHITE 0x01 239 #define NCF_ISDOTDOT 0x02 240 241 #ifdef DIAGNOSTIC 242 /* 243 * Grab an atomic snapshot of the name cache hash chain lengths 244 */ 245 SYSCTL_NODE(_debug, OID_AUTO, hashstat, CTLFLAG_RW, NULL, "hash table stats"); 246 247 static int 248 sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS) 249 { 250 int error; 251 struct nchashhead *ncpp; 252 struct namecache *ncp; 253 int n_nchash; 254 int count; 255 256 n_nchash = nchash + 1; /* nchash is max index, not count */ 257 if (!req->oldptr) 258 return SYSCTL_OUT(req, 0, n_nchash * sizeof(int)); 259 260 /* Scan hash tables for applicable entries */ 261 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { 262 CACHE_RLOCK(); 263 count = 0; 264 LIST_FOREACH(ncp, ncpp, nc_hash) { 265 count++; 266 } 267 CACHE_RUNLOCK(); 268 error = SYSCTL_OUT(req, &count, sizeof(count)); 269 if (error) 270 return (error); 271 } 272 return (0); 273 } 274 SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD| 275 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_rawnchash, "S,int", 276 "nchash chain lengths"); 277 278 static int 279 sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS) 280 { 281 int error; 282 struct nchashhead *ncpp; 283 struct namecache *ncp; 284 int n_nchash; 285 int count, maxlength, used, pct; 286 287 if (!req->oldptr) 288 return SYSCTL_OUT(req, 0, 4 * sizeof(int)); 289 290 n_nchash = nchash + 1; /* nchash is max index, not count */ 291 used = 0; 292 maxlength = 0; 293 294 /* Scan hash tables for applicable entries */ 295 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { 296 count = 0; 297 CACHE_RLOCK(); 298 LIST_FOREACH(ncp, ncpp, nc_hash) { 299 count++; 300 } 301 CACHE_RUNLOCK(); 302 if (count) 303 used++; 304 if (maxlength < count) 305 maxlength = count; 306 } 307 n_nchash = nchash + 1; 308 pct = (used * 100 * 100) / n_nchash; 309 error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash)); 310 if (error) 311 return (error); 312 error = SYSCTL_OUT(req, &used, sizeof(used)); 313 if (error) 314 return (error); 315 error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength)); 316 if (error) 317 return (error); 318 error = SYSCTL_OUT(req, &pct, sizeof(pct)); 319 if (error) 320 return (error); 321 return (0); 322 } 323 SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD| 324 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_nchash, "I", 325 "nchash chain lengths"); 326 #endif 327 328 /* 329 * cache_zap(): 330 * 331 * Removes a namecache entry from cache, whether it contains an actual 332 * pointer to a vnode or if it is just a negative cache entry. 333 */ 334 static void 335 cache_zap(ncp) 336 struct namecache *ncp; 337 { 338 struct vnode *vp; 339 340 rw_assert(&cache_lock, RA_WLOCKED); 341 CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp, ncp->nc_vp); 342 #ifdef KDTRACE_HOOKS 343 if (ncp->nc_vp != NULL) { 344 SDT_PROBE(vfs, namecache, zap, done, ncp->nc_dvp, 345 ncp->nc_name, ncp->nc_vp, 0, 0); 346 } else { 347 SDT_PROBE(vfs, namecache, zap_negative, done, ncp->nc_dvp, 348 ncp->nc_name, 0, 0, 0); 349 } 350 #endif 351 vp = NULL; 352 LIST_REMOVE(ncp, nc_hash); 353 if (ncp->nc_flag & NCF_ISDOTDOT) { 354 if (ncp == ncp->nc_dvp->v_cache_dd) 355 ncp->nc_dvp->v_cache_dd = NULL; 356 } else { 357 LIST_REMOVE(ncp, nc_src); 358 if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) { 359 vp = ncp->nc_dvp; 360 numcachehv--; 361 } 362 } 363 if (ncp->nc_vp) { 364 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst); 365 if (ncp == ncp->nc_vp->v_cache_dd) 366 ncp->nc_vp->v_cache_dd = NULL; 367 } else { 368 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 369 numneg--; 370 } 371 numcache--; 372 cache_free(ncp); 373 if (vp) 374 vdrop(vp); 375 } 376 377 /* 378 * Lookup an entry in the cache 379 * 380 * Lookup is called with dvp pointing to the directory to search, 381 * cnp pointing to the name of the entry being sought. If the lookup 382 * succeeds, the vnode is returned in *vpp, and a status of -1 is 383 * returned. If the lookup determines that the name does not exist 384 * (negative cacheing), a status of ENOENT is returned. If the lookup 385 * fails, a status of zero is returned. If the directory vnode is 386 * recycled out from under us due to a forced unmount, a status of 387 * ENOENT is returned. 388 * 389 * vpp is locked and ref'd on return. If we're looking up DOTDOT, dvp is 390 * unlocked. If we're looking up . an extra ref is taken, but the lock is 391 * not recursively acquired. 392 */ 393 394 int 395 cache_lookup(dvp, vpp, cnp) 396 struct vnode *dvp; 397 struct vnode **vpp; 398 struct componentname *cnp; 399 { 400 struct namecache *ncp; 401 uint32_t hash; 402 int error, ltype, wlocked; 403 404 if (!doingcache) { 405 cnp->cn_flags &= ~MAKEENTRY; 406 return (0); 407 } 408 retry: 409 CACHE_RLOCK(); 410 wlocked = 0; 411 numcalls++; 412 error = 0; 413 414 retry_wlocked: 415 if (cnp->cn_nameptr[0] == '.') { 416 if (cnp->cn_namelen == 1) { 417 *vpp = dvp; 418 CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .", 419 dvp, cnp->cn_nameptr); 420 dothits++; 421 SDT_PROBE(vfs, namecache, lookup, hit, dvp, ".", 422 *vpp, 0, 0); 423 goto success; 424 } 425 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 426 dotdothits++; 427 if (dvp->v_cache_dd == NULL) { 428 SDT_PROBE(vfs, namecache, lookup, miss, dvp, 429 "..", NULL, 0, 0); 430 goto unlock; 431 } 432 if ((cnp->cn_flags & MAKEENTRY) == 0) { 433 if (!wlocked && !CACHE_UPGRADE_LOCK()) 434 goto wlock; 435 if (dvp->v_cache_dd->nc_flag & NCF_ISDOTDOT) 436 cache_zap(dvp->v_cache_dd); 437 dvp->v_cache_dd = NULL; 438 CACHE_WUNLOCK(); 439 return (0); 440 } 441 if (dvp->v_cache_dd->nc_flag & NCF_ISDOTDOT) 442 *vpp = dvp->v_cache_dd->nc_vp; 443 else 444 *vpp = dvp->v_cache_dd->nc_dvp; 445 /* Return failure if negative entry was found. */ 446 if (*vpp == NULL) { 447 ncp = dvp->v_cache_dd; 448 goto negative_success; 449 } 450 CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..", 451 dvp, cnp->cn_nameptr, *vpp); 452 SDT_PROBE(vfs, namecache, lookup, hit, dvp, "..", 453 *vpp, 0, 0); 454 goto success; 455 } 456 } 457 458 hash = fnv_32_buf(cnp->cn_nameptr, cnp->cn_namelen, FNV1_32_INIT); 459 hash = fnv_32_buf(&dvp, sizeof(dvp), hash); 460 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 461 numchecks++; 462 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 463 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 464 break; 465 } 466 467 /* We failed to find an entry */ 468 if (ncp == NULL) { 469 SDT_PROBE(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr, 470 NULL, 0, 0); 471 if ((cnp->cn_flags & MAKEENTRY) == 0) { 472 nummisszap++; 473 } else { 474 nummiss++; 475 } 476 nchstats.ncs_miss++; 477 goto unlock; 478 } 479 480 /* We don't want to have an entry, so dump it */ 481 if ((cnp->cn_flags & MAKEENTRY) == 0) { 482 numposzaps++; 483 nchstats.ncs_badhits++; 484 if (!wlocked && !CACHE_UPGRADE_LOCK()) 485 goto wlock; 486 cache_zap(ncp); 487 CACHE_WUNLOCK(); 488 return (0); 489 } 490 491 /* We found a "positive" match, return the vnode */ 492 if (ncp->nc_vp) { 493 numposhits++; 494 nchstats.ncs_goodhits++; 495 *vpp = ncp->nc_vp; 496 CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p", 497 dvp, cnp->cn_nameptr, *vpp, ncp); 498 SDT_PROBE(vfs, namecache, lookup, hit, dvp, ncp->nc_name, 499 *vpp, 0, 0); 500 goto success; 501 } 502 503 negative_success: 504 /* We found a negative match, and want to create it, so purge */ 505 if (cnp->cn_nameiop == CREATE) { 506 numnegzaps++; 507 nchstats.ncs_badhits++; 508 if (!wlocked && !CACHE_UPGRADE_LOCK()) 509 goto wlock; 510 cache_zap(ncp); 511 CACHE_WUNLOCK(); 512 return (0); 513 } 514 515 if (!wlocked && !CACHE_UPGRADE_LOCK()) 516 goto wlock; 517 numneghits++; 518 /* 519 * We found a "negative" match, so we shift it to the end of 520 * the "negative" cache entries queue to satisfy LRU. Also, 521 * check to see if the entry is a whiteout; indicate this to 522 * the componentname, if so. 523 */ 524 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 525 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 526 nchstats.ncs_neghits++; 527 if (ncp->nc_flag & NCF_WHITE) 528 cnp->cn_flags |= ISWHITEOUT; 529 SDT_PROBE(vfs, namecache, lookup, hit_negative, dvp, ncp->nc_name, 530 0, 0, 0); 531 CACHE_WUNLOCK(); 532 return (ENOENT); 533 534 wlock: 535 /* 536 * We need to update the cache after our lookup, so upgrade to 537 * a write lock and retry the operation. 538 */ 539 CACHE_RUNLOCK(); 540 CACHE_WLOCK(); 541 numupgrades++; 542 wlocked = 1; 543 goto retry_wlocked; 544 545 success: 546 /* 547 * On success we return a locked and ref'd vnode as per the lookup 548 * protocol. 549 */ 550 if (dvp == *vpp) { /* lookup on "." */ 551 VREF(*vpp); 552 if (wlocked) 553 CACHE_WUNLOCK(); 554 else 555 CACHE_RUNLOCK(); 556 /* 557 * When we lookup "." we still can be asked to lock it 558 * differently... 559 */ 560 ltype = cnp->cn_lkflags & LK_TYPE_MASK; 561 if (ltype != VOP_ISLOCKED(*vpp)) { 562 if (ltype == LK_EXCLUSIVE) { 563 vn_lock(*vpp, LK_UPGRADE | LK_RETRY); 564 if ((*vpp)->v_iflag & VI_DOOMED) { 565 /* forced unmount */ 566 vrele(*vpp); 567 *vpp = NULL; 568 return (ENOENT); 569 } 570 } else 571 vn_lock(*vpp, LK_DOWNGRADE | LK_RETRY); 572 } 573 return (-1); 574 } 575 ltype = 0; /* silence gcc warning */ 576 if (cnp->cn_flags & ISDOTDOT) { 577 ltype = VOP_ISLOCKED(dvp); 578 VOP_UNLOCK(dvp, 0); 579 } 580 VI_LOCK(*vpp); 581 if (wlocked) 582 CACHE_WUNLOCK(); 583 else 584 CACHE_RUNLOCK(); 585 error = vget(*vpp, cnp->cn_lkflags | LK_INTERLOCK, cnp->cn_thread); 586 if (cnp->cn_flags & ISDOTDOT) { 587 vn_lock(dvp, ltype | LK_RETRY); 588 if (dvp->v_iflag & VI_DOOMED) { 589 if (error == 0) 590 vput(*vpp); 591 *vpp = NULL; 592 return (ENOENT); 593 } 594 } 595 if (error) { 596 *vpp = NULL; 597 goto retry; 598 } 599 if ((cnp->cn_flags & ISLASTCN) && 600 (cnp->cn_lkflags & LK_TYPE_MASK) == LK_EXCLUSIVE) { 601 ASSERT_VOP_ELOCKED(*vpp, "cache_lookup"); 602 } 603 return (-1); 604 605 unlock: 606 if (wlocked) 607 CACHE_WUNLOCK(); 608 else 609 CACHE_RUNLOCK(); 610 return (0); 611 } 612 613 /* 614 * Add an entry to the cache. 615 */ 616 void 617 cache_enter(dvp, vp, cnp) 618 struct vnode *dvp; 619 struct vnode *vp; 620 struct componentname *cnp; 621 { 622 struct namecache *ncp, *n2; 623 struct nchashhead *ncpp; 624 uint32_t hash; 625 int flag; 626 int hold; 627 int zap; 628 int len; 629 630 CTR3(KTR_VFS, "cache_enter(%p, %p, %s)", dvp, vp, cnp->cn_nameptr); 631 VNASSERT(vp == NULL || (vp->v_iflag & VI_DOOMED) == 0, vp, 632 ("cache_enter: Adding a doomed vnode")); 633 VNASSERT(dvp == NULL || (dvp->v_iflag & VI_DOOMED) == 0, dvp, 634 ("cache_enter: Doomed vnode used as src")); 635 636 if (!doingcache) 637 return; 638 639 /* 640 * Avoid blowout in namecache entries. 641 */ 642 if (numcache >= desiredvnodes * ncsizefactor) 643 return; 644 645 flag = 0; 646 if (cnp->cn_nameptr[0] == '.') { 647 if (cnp->cn_namelen == 1) 648 return; 649 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 650 CACHE_WLOCK(); 651 /* 652 * If dotdot entry already exists, just retarget it 653 * to new parent vnode, otherwise continue with new 654 * namecache entry allocation. 655 */ 656 if ((ncp = dvp->v_cache_dd) != NULL && 657 ncp->nc_flag & NCF_ISDOTDOT) { 658 KASSERT(ncp->nc_dvp == dvp, 659 ("wrong isdotdot parent")); 660 if (ncp->nc_vp != NULL) 661 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, 662 ncp, nc_dst); 663 else 664 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 665 if (vp != NULL) 666 TAILQ_INSERT_HEAD(&vp->v_cache_dst, 667 ncp, nc_dst); 668 else 669 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 670 ncp->nc_vp = vp; 671 CACHE_WUNLOCK(); 672 return; 673 } 674 dvp->v_cache_dd = NULL; 675 SDT_PROBE(vfs, namecache, enter, done, dvp, "..", vp, 676 0, 0); 677 CACHE_WUNLOCK(); 678 flag = NCF_ISDOTDOT; 679 } 680 } 681 682 hold = 0; 683 zap = 0; 684 685 /* 686 * Calculate the hash key and setup as much of the new 687 * namecache entry as possible before acquiring the lock. 688 */ 689 ncp = cache_alloc(cnp->cn_namelen); 690 ncp->nc_vp = vp; 691 ncp->nc_dvp = dvp; 692 ncp->nc_flag = flag; 693 len = ncp->nc_nlen = cnp->cn_namelen; 694 hash = fnv_32_buf(cnp->cn_nameptr, len, FNV1_32_INIT); 695 strlcpy(ncp->nc_name, cnp->cn_nameptr, len + 1); 696 hash = fnv_32_buf(&dvp, sizeof(dvp), hash); 697 CACHE_WLOCK(); 698 699 /* 700 * See if this vnode or negative entry is already in the cache 701 * with this name. This can happen with concurrent lookups of 702 * the same path name. 703 */ 704 ncpp = NCHHASH(hash); 705 LIST_FOREACH(n2, ncpp, nc_hash) { 706 if (n2->nc_dvp == dvp && 707 n2->nc_nlen == cnp->cn_namelen && 708 !bcmp(n2->nc_name, cnp->cn_nameptr, n2->nc_nlen)) { 709 CACHE_WUNLOCK(); 710 cache_free(ncp); 711 return; 712 } 713 } 714 715 if (flag == NCF_ISDOTDOT) { 716 /* 717 * See if we are trying to add .. entry, but some other lookup 718 * has populated v_cache_dd pointer already. 719 */ 720 if (dvp->v_cache_dd != NULL) { 721 CACHE_WUNLOCK(); 722 cache_free(ncp); 723 return; 724 } 725 KASSERT(vp == NULL || vp->v_type == VDIR, 726 ("wrong vnode type %p", vp)); 727 dvp->v_cache_dd = ncp; 728 } 729 730 numcache++; 731 if (!vp) { 732 numneg++; 733 if (cnp->cn_flags & ISWHITEOUT) 734 ncp->nc_flag |= NCF_WHITE; 735 } else if (vp->v_type == VDIR) { 736 if (flag != NCF_ISDOTDOT) { 737 if ((n2 = vp->v_cache_dd) != NULL && 738 (n2->nc_flag & NCF_ISDOTDOT) != 0) 739 cache_zap(n2); 740 vp->v_cache_dd = ncp; 741 } 742 } else { 743 vp->v_cache_dd = NULL; 744 } 745 746 /* 747 * Insert the new namecache entry into the appropriate chain 748 * within the cache entries table. 749 */ 750 LIST_INSERT_HEAD(ncpp, ncp, nc_hash); 751 if (flag != NCF_ISDOTDOT) { 752 if (LIST_EMPTY(&dvp->v_cache_src)) { 753 hold = 1; 754 numcachehv++; 755 } 756 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); 757 } 758 759 /* 760 * If the entry is "negative", we place it into the 761 * "negative" cache queue, otherwise, we place it into the 762 * destination vnode's cache entries queue. 763 */ 764 if (vp) { 765 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); 766 SDT_PROBE(vfs, namecache, enter, done, dvp, ncp->nc_name, vp, 767 0, 0); 768 } else { 769 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 770 SDT_PROBE(vfs, namecache, enter_negative, done, dvp, 771 ncp->nc_name, 0, 0, 0); 772 } 773 if (numneg * ncnegfactor > numcache) { 774 ncp = TAILQ_FIRST(&ncneg); 775 zap = 1; 776 } 777 if (hold) 778 vhold(dvp); 779 if (zap) 780 cache_zap(ncp); 781 CACHE_WUNLOCK(); 782 } 783 784 /* 785 * Name cache initialization, from vfs_init() when we are booting 786 */ 787 static void 788 nchinit(void *dummy __unused) 789 { 790 791 TAILQ_INIT(&ncneg); 792 793 cache_zone_small = uma_zcreate("S VFS Cache", CACHE_ZONE_SMALL, NULL, 794 NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 795 cache_zone_large = uma_zcreate("L VFS Cache", CACHE_ZONE_LARGE, NULL, 796 NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 797 798 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash); 799 } 800 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL); 801 802 803 /* 804 * Invalidate all entries to a particular vnode. 805 */ 806 void 807 cache_purge(vp) 808 struct vnode *vp; 809 { 810 811 CTR1(KTR_VFS, "cache_purge(%p)", vp); 812 SDT_PROBE(vfs, namecache, purge, done, vp, 0, 0, 0, 0); 813 CACHE_WLOCK(); 814 while (!LIST_EMPTY(&vp->v_cache_src)) 815 cache_zap(LIST_FIRST(&vp->v_cache_src)); 816 while (!TAILQ_EMPTY(&vp->v_cache_dst)) 817 cache_zap(TAILQ_FIRST(&vp->v_cache_dst)); 818 if (vp->v_cache_dd != NULL) { 819 KASSERT(vp->v_cache_dd->nc_flag & NCF_ISDOTDOT, 820 ("lost dotdot link")); 821 cache_zap(vp->v_cache_dd); 822 } 823 KASSERT(vp->v_cache_dd == NULL, ("incomplete purge")); 824 CACHE_WUNLOCK(); 825 } 826 827 /* 828 * Invalidate all negative entries for a particular directory vnode. 829 */ 830 void 831 cache_purge_negative(vp) 832 struct vnode *vp; 833 { 834 struct namecache *cp, *ncp; 835 836 CTR1(KTR_VFS, "cache_purge_negative(%p)", vp); 837 SDT_PROBE(vfs, namecache, purge_negative, done, vp, 0, 0, 0, 0); 838 CACHE_WLOCK(); 839 LIST_FOREACH_SAFE(cp, &vp->v_cache_src, nc_src, ncp) { 840 if (cp->nc_vp == NULL) 841 cache_zap(cp); 842 } 843 CACHE_WUNLOCK(); 844 } 845 846 /* 847 * Flush all entries referencing a particular filesystem. 848 */ 849 void 850 cache_purgevfs(mp) 851 struct mount *mp; 852 { 853 struct nchashhead *ncpp; 854 struct namecache *ncp, *nnp; 855 856 /* Scan hash tables for applicable entries */ 857 SDT_PROBE(vfs, namecache, purgevfs, done, mp, 0, 0, 0, 0); 858 CACHE_WLOCK(); 859 for (ncpp = &nchashtbl[nchash]; ncpp >= nchashtbl; ncpp--) { 860 LIST_FOREACH_SAFE(ncp, ncpp, nc_hash, nnp) { 861 if (ncp->nc_dvp->v_mount == mp) 862 cache_zap(ncp); 863 } 864 } 865 CACHE_WUNLOCK(); 866 } 867 868 /* 869 * Perform canonical checks and cache lookup and pass on to filesystem 870 * through the vop_cachedlookup only if needed. 871 */ 872 873 int 874 vfs_cache_lookup(ap) 875 struct vop_lookup_args /* { 876 struct vnode *a_dvp; 877 struct vnode **a_vpp; 878 struct componentname *a_cnp; 879 } */ *ap; 880 { 881 struct vnode *dvp; 882 int error; 883 struct vnode **vpp = ap->a_vpp; 884 struct componentname *cnp = ap->a_cnp; 885 struct ucred *cred = cnp->cn_cred; 886 int flags = cnp->cn_flags; 887 struct thread *td = cnp->cn_thread; 888 889 *vpp = NULL; 890 dvp = ap->a_dvp; 891 892 if (dvp->v_type != VDIR) 893 return (ENOTDIR); 894 895 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && 896 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 897 return (EROFS); 898 899 error = VOP_ACCESS(dvp, VEXEC, cred, td); 900 if (error) 901 return (error); 902 903 error = cache_lookup(dvp, vpp, cnp); 904 if (error == 0) 905 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); 906 if (error == -1) 907 return (0); 908 return (error); 909 } 910 911 912 #ifndef _SYS_SYSPROTO_H_ 913 struct __getcwd_args { 914 u_char *buf; 915 u_int buflen; 916 }; 917 #endif 918 919 /* 920 * XXX All of these sysctls would probably be more productive dead. 921 */ 922 static int disablecwd; 923 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, 924 "Disable the getcwd syscall"); 925 926 /* Implementation of the getcwd syscall. */ 927 int 928 sys___getcwd(td, uap) 929 struct thread *td; 930 struct __getcwd_args *uap; 931 { 932 933 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen)); 934 } 935 936 int 937 kern___getcwd(struct thread *td, u_char *buf, enum uio_seg bufseg, u_int buflen) 938 { 939 char *bp, *tmpbuf; 940 struct filedesc *fdp; 941 struct vnode *cdir, *rdir; 942 int error, vfslocked; 943 944 if (disablecwd) 945 return (ENODEV); 946 if (buflen < 2) 947 return (EINVAL); 948 if (buflen > MAXPATHLEN) 949 buflen = MAXPATHLEN; 950 951 tmpbuf = malloc(buflen, M_TEMP, M_WAITOK); 952 fdp = td->td_proc->p_fd; 953 FILEDESC_SLOCK(fdp); 954 cdir = fdp->fd_cdir; 955 VREF(cdir); 956 rdir = fdp->fd_rdir; 957 VREF(rdir); 958 FILEDESC_SUNLOCK(fdp); 959 error = vn_fullpath1(td, cdir, rdir, tmpbuf, &bp, buflen); 960 vfslocked = VFS_LOCK_GIANT(rdir->v_mount); 961 vrele(rdir); 962 VFS_UNLOCK_GIANT(vfslocked); 963 vfslocked = VFS_LOCK_GIANT(cdir->v_mount); 964 vrele(cdir); 965 VFS_UNLOCK_GIANT(vfslocked); 966 967 if (!error) { 968 if (bufseg == UIO_SYSSPACE) 969 bcopy(bp, buf, strlen(bp) + 1); 970 else 971 error = copyout(bp, buf, strlen(bp) + 1); 972 #ifdef KTRACE 973 if (KTRPOINT(curthread, KTR_NAMEI)) 974 ktrnamei(bp); 975 #endif 976 } 977 free(tmpbuf, M_TEMP); 978 return (error); 979 } 980 981 /* 982 * Thus begins the fullpath magic. 983 */ 984 985 #undef STATNODE 986 #define STATNODE(name, descr) \ 987 static u_int name; \ 988 SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, descr) 989 990 static int disablefullpath; 991 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0, 992 "Disable the vn_fullpath function"); 993 994 /* These count for kern___getcwd(), too. */ 995 STATNODE(numfullpathcalls, "Number of fullpath search calls"); 996 STATNODE(numfullpathfail1, "Number of fullpath search errors (ENOTDIR)"); 997 STATNODE(numfullpathfail2, 998 "Number of fullpath search errors (VOP_VPTOCNP failures)"); 999 STATNODE(numfullpathfail4, "Number of fullpath search errors (ENOMEM)"); 1000 STATNODE(numfullpathfound, "Number of successful fullpath calls"); 1001 1002 /* 1003 * Retrieve the full filesystem path that correspond to a vnode from the name 1004 * cache (if available) 1005 */ 1006 int 1007 vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf) 1008 { 1009 char *buf; 1010 struct filedesc *fdp; 1011 struct vnode *rdir; 1012 int error, vfslocked; 1013 1014 if (disablefullpath) 1015 return (ENODEV); 1016 if (vn == NULL) 1017 return (EINVAL); 1018 1019 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 1020 fdp = td->td_proc->p_fd; 1021 FILEDESC_SLOCK(fdp); 1022 rdir = fdp->fd_rdir; 1023 VREF(rdir); 1024 FILEDESC_SUNLOCK(fdp); 1025 error = vn_fullpath1(td, vn, rdir, buf, retbuf, MAXPATHLEN); 1026 vfslocked = VFS_LOCK_GIANT(rdir->v_mount); 1027 vrele(rdir); 1028 VFS_UNLOCK_GIANT(vfslocked); 1029 1030 if (!error) 1031 *freebuf = buf; 1032 else 1033 free(buf, M_TEMP); 1034 return (error); 1035 } 1036 1037 /* 1038 * This function is similar to vn_fullpath, but it attempts to lookup the 1039 * pathname relative to the global root mount point. This is required for the 1040 * auditing sub-system, as audited pathnames must be absolute, relative to the 1041 * global root mount point. 1042 */ 1043 int 1044 vn_fullpath_global(struct thread *td, struct vnode *vn, 1045 char **retbuf, char **freebuf) 1046 { 1047 char *buf; 1048 int error; 1049 1050 if (disablefullpath) 1051 return (ENODEV); 1052 if (vn == NULL) 1053 return (EINVAL); 1054 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 1055 error = vn_fullpath1(td, vn, rootvnode, buf, retbuf, MAXPATHLEN); 1056 if (!error) 1057 *freebuf = buf; 1058 else 1059 free(buf, M_TEMP); 1060 return (error); 1061 } 1062 1063 int 1064 vn_vptocnp(struct vnode **vp, struct ucred *cred, char *buf, u_int *buflen) 1065 { 1066 int error; 1067 1068 CACHE_RLOCK(); 1069 error = vn_vptocnp_locked(vp, cred, buf, buflen); 1070 if (error == 0) { 1071 /* 1072 * vn_vptocnp_locked() dropped hold acquired by 1073 * VOP_VPTOCNP immediately after locking the 1074 * cache. Since we are going to drop the cache rlock, 1075 * re-hold the result. 1076 */ 1077 vhold(*vp); 1078 CACHE_RUNLOCK(); 1079 } 1080 return (error); 1081 } 1082 1083 static int 1084 vn_vptocnp_locked(struct vnode **vp, struct ucred *cred, char *buf, 1085 u_int *buflen) 1086 { 1087 struct vnode *dvp; 1088 struct namecache *ncp; 1089 int error, vfslocked; 1090 1091 TAILQ_FOREACH(ncp, &((*vp)->v_cache_dst), nc_dst) { 1092 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 1093 break; 1094 } 1095 if (ncp != NULL) { 1096 if (*buflen < ncp->nc_nlen) { 1097 CACHE_RUNLOCK(); 1098 numfullpathfail4++; 1099 error = ENOMEM; 1100 SDT_PROBE(vfs, namecache, fullpath, return, error, 1101 vp, NULL, 0, 0); 1102 return (error); 1103 } 1104 *buflen -= ncp->nc_nlen; 1105 memcpy(buf + *buflen, ncp->nc_name, ncp->nc_nlen); 1106 SDT_PROBE(vfs, namecache, fullpath, hit, ncp->nc_dvp, 1107 ncp->nc_name, vp, 0, 0); 1108 *vp = ncp->nc_dvp; 1109 return (0); 1110 } 1111 SDT_PROBE(vfs, namecache, fullpath, miss, vp, 0, 0, 0, 0); 1112 1113 vhold(*vp); 1114 CACHE_RUNLOCK(); 1115 vfslocked = VFS_LOCK_GIANT((*vp)->v_mount); 1116 vn_lock(*vp, LK_SHARED | LK_RETRY); 1117 error = VOP_VPTOCNP(*vp, &dvp, cred, buf, buflen); 1118 VOP_UNLOCK(*vp, 0); 1119 vdrop(*vp); 1120 VFS_UNLOCK_GIANT(vfslocked); 1121 if (error) { 1122 numfullpathfail2++; 1123 SDT_PROBE(vfs, namecache, fullpath, return, error, vp, 1124 NULL, 0, 0); 1125 return (error); 1126 } 1127 1128 *vp = dvp; 1129 CACHE_RLOCK(); 1130 if ((*vp)->v_iflag & VI_DOOMED) { 1131 /* forced unmount */ 1132 CACHE_RUNLOCK(); 1133 vdrop(*vp); 1134 error = ENOENT; 1135 SDT_PROBE(vfs, namecache, fullpath, return, error, vp, 1136 NULL, 0, 0); 1137 return (error); 1138 } 1139 vdrop(*vp); 1140 1141 return (0); 1142 } 1143 1144 /* 1145 * The magic behind kern___getcwd() and vn_fullpath(). 1146 */ 1147 static int 1148 vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 1149 char *buf, char **retbuf, u_int buflen) 1150 { 1151 int error, slash_prefixed; 1152 #ifdef KDTRACE_HOOKS 1153 struct vnode *startvp = vp; 1154 #endif 1155 1156 buflen--; 1157 buf[buflen] = '\0'; 1158 error = 0; 1159 slash_prefixed = 0; 1160 1161 SDT_PROBE(vfs, namecache, fullpath, entry, vp, 0, 0, 0, 0); 1162 numfullpathcalls++; 1163 CACHE_RLOCK(); 1164 if (vp->v_type != VDIR) { 1165 error = vn_vptocnp_locked(&vp, td->td_ucred, buf, &buflen); 1166 if (error) 1167 return (error); 1168 if (buflen == 0) { 1169 CACHE_RUNLOCK(); 1170 return (ENOMEM); 1171 } 1172 buf[--buflen] = '/'; 1173 slash_prefixed = 1; 1174 } 1175 while (vp != rdir && vp != rootvnode) { 1176 if (vp->v_vflag & VV_ROOT) { 1177 if (vp->v_iflag & VI_DOOMED) { /* forced unmount */ 1178 CACHE_RUNLOCK(); 1179 error = ENOENT; 1180 SDT_PROBE(vfs, namecache, fullpath, return, 1181 error, vp, NULL, 0, 0); 1182 break; 1183 } 1184 vp = vp->v_mount->mnt_vnodecovered; 1185 continue; 1186 } 1187 if (vp->v_type != VDIR) { 1188 CACHE_RUNLOCK(); 1189 numfullpathfail1++; 1190 error = ENOTDIR; 1191 SDT_PROBE(vfs, namecache, fullpath, return, 1192 error, vp, NULL, 0, 0); 1193 break; 1194 } 1195 error = vn_vptocnp_locked(&vp, td->td_ucred, buf, &buflen); 1196 if (error) 1197 break; 1198 if (buflen == 0) { 1199 CACHE_RUNLOCK(); 1200 error = ENOMEM; 1201 SDT_PROBE(vfs, namecache, fullpath, return, error, 1202 startvp, NULL, 0, 0); 1203 break; 1204 } 1205 buf[--buflen] = '/'; 1206 slash_prefixed = 1; 1207 } 1208 if (error) 1209 return (error); 1210 if (!slash_prefixed) { 1211 if (buflen == 0) { 1212 CACHE_RUNLOCK(); 1213 numfullpathfail4++; 1214 SDT_PROBE(vfs, namecache, fullpath, return, ENOMEM, 1215 startvp, NULL, 0, 0); 1216 return (ENOMEM); 1217 } 1218 buf[--buflen] = '/'; 1219 } 1220 numfullpathfound++; 1221 CACHE_RUNLOCK(); 1222 1223 SDT_PROBE(vfs, namecache, fullpath, return, 0, startvp, buf + buflen, 1224 0, 0); 1225 *retbuf = buf + buflen; 1226 return (0); 1227 } 1228 1229 int 1230 vn_commname(struct vnode *vp, char *buf, u_int buflen) 1231 { 1232 struct namecache *ncp; 1233 int l; 1234 1235 CACHE_RLOCK(); 1236 TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst) 1237 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 1238 break; 1239 if (ncp == NULL) { 1240 CACHE_RUNLOCK(); 1241 return (ENOENT); 1242 } 1243 l = min(ncp->nc_nlen, buflen - 1); 1244 memcpy(buf, ncp->nc_name, l); 1245 CACHE_RUNLOCK(); 1246 buf[l] = '\0'; 1247 return (0); 1248 }
Cache object: 319906fea80ecd331344000de24b2dfd
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