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_ktrace.h" 39 40 #include <sys/param.h> 41 #include <sys/systm.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/fcntl.h> 48 #include <sys/mount.h> 49 #include <sys/namei.h> 50 #include <sys/proc.h> 51 #include <sys/rwlock.h> 52 #include <sys/sdt.h> 53 #include <sys/syscallsubr.h> 54 #include <sys/sysctl.h> 55 #include <sys/sysproto.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, "struct vnode *", "char *", 65 "struct vnode *"); 66 SDT_PROBE_DEFINE2(vfs, namecache, enter_negative, done, "struct vnode *", 67 "char *"); 68 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, entry, "struct vnode *"); 69 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, hit, "struct vnode *", 70 "char *", "struct vnode *"); 71 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, miss, "struct vnode *"); 72 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, return, "int", 73 "struct vnode *", "char *"); 74 SDT_PROBE_DEFINE3(vfs, namecache, lookup, hit, "struct vnode *", "char *", 75 "struct vnode *"); 76 SDT_PROBE_DEFINE2(vfs, namecache, lookup, hit__negative, 77 "struct vnode *", "char *"); 78 SDT_PROBE_DEFINE2(vfs, namecache, lookup, miss, "struct vnode *", 79 "char *"); 80 SDT_PROBE_DEFINE1(vfs, namecache, purge, done, "struct vnode *"); 81 SDT_PROBE_DEFINE1(vfs, namecache, purge_negative, done, "struct vnode *"); 82 SDT_PROBE_DEFINE1(vfs, namecache, purgevfs, done, "struct mount *"); 83 SDT_PROBE_DEFINE3(vfs, namecache, zap, done, "struct vnode *", "char *", 84 "struct vnode *"); 85 SDT_PROBE_DEFINE2(vfs, namecache, zap_negative, 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 * struct namecache_ts repeats struct namecache layout up to the 106 * nc_nlen member. 107 * struct namecache_ts is used in place of struct namecache when time(s) need 108 * to be stored. The nc_dotdottime field is used when a cache entry is mapping 109 * both a non-dotdot directory name plus dotdot for the directory's 110 * parent. 111 */ 112 struct namecache_ts { 113 LIST_ENTRY(namecache) nc_hash; /* hash chain */ 114 LIST_ENTRY(namecache) nc_src; /* source vnode list */ 115 TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */ 116 struct vnode *nc_dvp; /* vnode of parent of name */ 117 struct vnode *nc_vp; /* vnode the name refers to */ 118 u_char nc_flag; /* flag bits */ 119 u_char nc_nlen; /* length of name */ 120 struct timespec nc_time; /* timespec provided by fs */ 121 struct timespec nc_dotdottime; /* dotdot timespec provided by fs */ 122 int nc_ticks; /* ticks value when entry was added */ 123 char nc_name[0]; /* segment name + nul */ 124 }; 125 126 /* 127 * Flags in namecache.nc_flag 128 */ 129 #define NCF_WHITE 0x01 130 #define NCF_ISDOTDOT 0x02 131 #define NCF_TS 0x04 132 #define NCF_DTS 0x08 133 134 /* 135 * Name caching works as follows: 136 * 137 * Names found by directory scans are retained in a cache 138 * for future reference. It is managed LRU, so frequently 139 * used names will hang around. Cache is indexed by hash value 140 * obtained from (vp, name) where vp refers to the directory 141 * containing name. 142 * 143 * If it is a "negative" entry, (i.e. for a name that is known NOT to 144 * exist) the vnode pointer will be NULL. 145 * 146 * Upon reaching the last segment of a path, if the reference 147 * is for DELETE, or NOCACHE is set (rewrite), and the 148 * name is located in the cache, it will be dropped. 149 */ 150 151 /* 152 * Structures associated with name cacheing. 153 */ 154 #define NCHHASH(hash) \ 155 (&nchashtbl[(hash) & nchash]) 156 static LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */ 157 static TAILQ_HEAD(, namecache) ncneg; /* Hash Table */ 158 static u_long nchash; /* size of hash table */ 159 SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, 160 "Size of namecache hash table"); 161 static u_long ncnegfactor = 16; /* ratio of negative entries */ 162 SYSCTL_ULONG(_vfs, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, 163 "Ratio of negative namecache entries"); 164 static u_long numneg; /* number of negative entries allocated */ 165 SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, 166 "Number of negative entries in namecache"); 167 static u_long numcache; /* number of cache entries allocated */ 168 SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, 169 "Number of namecache entries"); 170 static u_long numcachehv; /* number of cache entries with vnodes held */ 171 SYSCTL_ULONG(_debug, OID_AUTO, numcachehv, CTLFLAG_RD, &numcachehv, 0, 172 "Number of namecache entries with vnodes held"); 173 static u_int ncsizefactor = 2; 174 SYSCTL_UINT(_vfs, OID_AUTO, ncsizefactor, CTLFLAG_RW, &ncsizefactor, 0, 175 "Size factor for namecache"); 176 177 struct nchstats nchstats; /* cache effectiveness statistics */ 178 179 static struct rwlock cache_lock; 180 RW_SYSINIT(vfscache, &cache_lock, "Name Cache"); 181 182 #define CACHE_UPGRADE_LOCK() rw_try_upgrade(&cache_lock) 183 #define CACHE_RLOCK() rw_rlock(&cache_lock) 184 #define CACHE_RUNLOCK() rw_runlock(&cache_lock) 185 #define CACHE_WLOCK() rw_wlock(&cache_lock) 186 #define CACHE_WUNLOCK() rw_wunlock(&cache_lock) 187 188 /* 189 * UMA zones for the VFS cache. 190 * 191 * The small cache is used for entries with short names, which are the 192 * most common. The large cache is used for entries which are too big to 193 * fit in the small cache. 194 */ 195 static uma_zone_t cache_zone_small; 196 static uma_zone_t cache_zone_small_ts; 197 static uma_zone_t cache_zone_large; 198 static uma_zone_t cache_zone_large_ts; 199 200 #define CACHE_PATH_CUTOFF 35 201 202 static struct namecache * 203 cache_alloc(int len, int ts) 204 { 205 206 if (len > CACHE_PATH_CUTOFF) { 207 if (ts) 208 return (uma_zalloc(cache_zone_large_ts, M_WAITOK)); 209 else 210 return (uma_zalloc(cache_zone_large, M_WAITOK)); 211 } 212 if (ts) 213 return (uma_zalloc(cache_zone_small_ts, M_WAITOK)); 214 else 215 return (uma_zalloc(cache_zone_small, M_WAITOK)); 216 } 217 218 static void 219 cache_free(struct namecache *ncp) 220 { 221 int ts; 222 223 if (ncp == NULL) 224 return; 225 ts = ncp->nc_flag & NCF_TS; 226 if (ncp->nc_nlen <= CACHE_PATH_CUTOFF) { 227 if (ts) 228 uma_zfree(cache_zone_small_ts, ncp); 229 else 230 uma_zfree(cache_zone_small, ncp); 231 } else if (ts) 232 uma_zfree(cache_zone_large_ts, ncp); 233 else 234 uma_zfree(cache_zone_large, ncp); 235 } 236 237 static char * 238 nc_get_name(struct namecache *ncp) 239 { 240 struct namecache_ts *ncp_ts; 241 242 if ((ncp->nc_flag & NCF_TS) == 0) 243 return (ncp->nc_name); 244 ncp_ts = (struct namecache_ts *)ncp; 245 return (ncp_ts->nc_name); 246 } 247 248 static void 249 cache_out_ts(struct namecache *ncp, struct timespec *tsp, int *ticksp) 250 { 251 252 KASSERT((ncp->nc_flag & NCF_TS) != 0 || 253 (tsp == NULL && ticksp == NULL), 254 ("No NCF_TS")); 255 256 if (tsp != NULL) 257 *tsp = ((struct namecache_ts *)ncp)->nc_time; 258 if (ticksp != NULL) 259 *ticksp = ((struct namecache_ts *)ncp)->nc_ticks; 260 } 261 262 static int doingcache = 1; /* 1 => enable the cache */ 263 SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0, 264 "VFS namecache enabled"); 265 266 /* Export size information to userland */ 267 SYSCTL_INT(_debug_sizeof, OID_AUTO, namecache, CTLFLAG_RD, SYSCTL_NULL_INT_PTR, 268 sizeof(struct namecache), "sizeof(struct namecache)"); 269 270 /* 271 * The new name cache statistics 272 */ 273 static SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, 274 "Name cache statistics"); 275 #define STATNODE(mode, name, var, descr) \ 276 SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, mode, var, 0, descr); 277 STATNODE(CTLFLAG_RD, numneg, &numneg, "Number of negative cache entries"); 278 STATNODE(CTLFLAG_RD, numcache, &numcache, "Number of cache entries"); 279 static u_long numcalls; STATNODE(CTLFLAG_RD, numcalls, &numcalls, 280 "Number of cache lookups"); 281 static u_long dothits; STATNODE(CTLFLAG_RD, dothits, &dothits, 282 "Number of '.' hits"); 283 static u_long dotdothits; STATNODE(CTLFLAG_RD, dotdothits, &dotdothits, 284 "Number of '..' hits"); 285 static u_long numchecks; STATNODE(CTLFLAG_RD, numchecks, &numchecks, 286 "Number of checks in lookup"); 287 static u_long nummiss; STATNODE(CTLFLAG_RD, nummiss, &nummiss, 288 "Number of cache misses"); 289 static u_long nummisszap; STATNODE(CTLFLAG_RD, nummisszap, &nummisszap, 290 "Number of cache misses we do not want to cache"); 291 static u_long numposzaps; STATNODE(CTLFLAG_RD, numposzaps, &numposzaps, 292 "Number of cache hits (positive) we do not want to cache"); 293 static u_long numposhits; STATNODE(CTLFLAG_RD, numposhits, &numposhits, 294 "Number of cache hits (positive)"); 295 static u_long numnegzaps; STATNODE(CTLFLAG_RD, numnegzaps, &numnegzaps, 296 "Number of cache hits (negative) we do not want to cache"); 297 static u_long numneghits; STATNODE(CTLFLAG_RD, numneghits, &numneghits, 298 "Number of cache hits (negative)"); 299 static u_long numupgrades; STATNODE(CTLFLAG_RD, numupgrades, &numupgrades, 300 "Number of updates of the cache after lookup (write lock + retry)"); 301 302 SYSCTL_OPAQUE(_vfs_cache, OID_AUTO, nchstats, CTLFLAG_RD | CTLFLAG_MPSAFE, 303 &nchstats, sizeof(nchstats), "LU", 304 "VFS cache effectiveness statistics"); 305 306 307 308 static void cache_zap(struct namecache *ncp); 309 static int vn_vptocnp_locked(struct vnode **vp, struct ucred *cred, char *buf, 310 u_int *buflen); 311 static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 312 char *buf, char **retbuf, u_int buflen); 313 314 static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); 315 316 #ifdef DIAGNOSTIC 317 /* 318 * Grab an atomic snapshot of the name cache hash chain lengths 319 */ 320 static SYSCTL_NODE(_debug, OID_AUTO, hashstat, CTLFLAG_RW, NULL, 321 "hash table stats"); 322 323 static int 324 sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS) 325 { 326 struct nchashhead *ncpp; 327 struct namecache *ncp; 328 int i, error, n_nchash, *cntbuf; 329 330 retry: 331 n_nchash = nchash + 1; /* nchash is max index, not count */ 332 if (req->oldptr == NULL) 333 return SYSCTL_OUT(req, 0, n_nchash * sizeof(int)); 334 cntbuf = malloc(n_nchash * sizeof(int), M_TEMP, M_ZERO | M_WAITOK); 335 CACHE_RLOCK(); 336 if (n_nchash != nchash + 1) { 337 CACHE_RUNLOCK(); 338 free(cntbuf, M_TEMP); 339 goto retry; 340 } 341 /* Scan hash tables counting entries */ 342 for (ncpp = nchashtbl, i = 0; i < n_nchash; ncpp++, i++) 343 LIST_FOREACH(ncp, ncpp, nc_hash) 344 cntbuf[i]++; 345 CACHE_RUNLOCK(); 346 for (error = 0, i = 0; i < n_nchash; i++) 347 if ((error = SYSCTL_OUT(req, &cntbuf[i], sizeof(int))) != 0) 348 break; 349 free(cntbuf, M_TEMP); 350 return (error); 351 } 352 SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD| 353 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_rawnchash, "S,int", 354 "nchash chain lengths"); 355 356 static int 357 sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS) 358 { 359 int error; 360 struct nchashhead *ncpp; 361 struct namecache *ncp; 362 int n_nchash; 363 int count, maxlength, used, pct; 364 365 if (!req->oldptr) 366 return SYSCTL_OUT(req, 0, 4 * sizeof(int)); 367 368 CACHE_RLOCK(); 369 n_nchash = nchash + 1; /* nchash is max index, not count */ 370 used = 0; 371 maxlength = 0; 372 373 /* Scan hash tables for applicable entries */ 374 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { 375 count = 0; 376 LIST_FOREACH(ncp, ncpp, nc_hash) { 377 count++; 378 } 379 if (count) 380 used++; 381 if (maxlength < count) 382 maxlength = count; 383 } 384 n_nchash = nchash + 1; 385 CACHE_RUNLOCK(); 386 pct = (used * 100) / (n_nchash / 100); 387 error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash)); 388 if (error) 389 return (error); 390 error = SYSCTL_OUT(req, &used, sizeof(used)); 391 if (error) 392 return (error); 393 error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength)); 394 if (error) 395 return (error); 396 error = SYSCTL_OUT(req, &pct, sizeof(pct)); 397 if (error) 398 return (error); 399 return (0); 400 } 401 SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD| 402 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_nchash, "I", 403 "nchash statistics (number of total/used buckets, maximum chain length, usage percentage)"); 404 #endif 405 406 /* 407 * cache_zap(): 408 * 409 * Removes a namecache entry from cache, whether it contains an actual 410 * pointer to a vnode or if it is just a negative cache entry. 411 */ 412 static void 413 cache_zap(ncp) 414 struct namecache *ncp; 415 { 416 struct vnode *vp; 417 418 rw_assert(&cache_lock, RA_WLOCKED); 419 CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp, ncp->nc_vp); 420 #ifdef KDTRACE_HOOKS 421 if (ncp->nc_vp != NULL) { 422 SDT_PROBE3(vfs, namecache, zap, done, ncp->nc_dvp, 423 nc_get_name(ncp), ncp->nc_vp); 424 } else { 425 SDT_PROBE2(vfs, namecache, zap_negative, done, ncp->nc_dvp, 426 nc_get_name(ncp)); 427 } 428 #endif 429 vp = NULL; 430 LIST_REMOVE(ncp, nc_hash); 431 if (ncp->nc_flag & NCF_ISDOTDOT) { 432 if (ncp == ncp->nc_dvp->v_cache_dd) 433 ncp->nc_dvp->v_cache_dd = NULL; 434 } else { 435 LIST_REMOVE(ncp, nc_src); 436 if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) { 437 vp = ncp->nc_dvp; 438 numcachehv--; 439 } 440 } 441 if (ncp->nc_vp) { 442 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst); 443 if (ncp == ncp->nc_vp->v_cache_dd) 444 ncp->nc_vp->v_cache_dd = NULL; 445 } else { 446 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 447 numneg--; 448 } 449 numcache--; 450 cache_free(ncp); 451 if (vp) 452 vdrop(vp); 453 } 454 455 /* 456 * Lookup an entry in the cache 457 * 458 * Lookup is called with dvp pointing to the directory to search, 459 * cnp pointing to the name of the entry being sought. If the lookup 460 * succeeds, the vnode is returned in *vpp, and a status of -1 is 461 * returned. If the lookup determines that the name does not exist 462 * (negative cacheing), a status of ENOENT is returned. If the lookup 463 * fails, a status of zero is returned. If the directory vnode is 464 * recycled out from under us due to a forced unmount, a status of 465 * ENOENT is returned. 466 * 467 * vpp is locked and ref'd on return. If we're looking up DOTDOT, dvp is 468 * unlocked. If we're looking up . an extra ref is taken, but the lock is 469 * not recursively acquired. 470 */ 471 472 int 473 cache_lookup(dvp, vpp, cnp, tsp, ticksp) 474 struct vnode *dvp; 475 struct vnode **vpp; 476 struct componentname *cnp; 477 struct timespec *tsp; 478 int *ticksp; 479 { 480 struct namecache *ncp; 481 uint32_t hash; 482 int error, ltype, wlocked; 483 484 if (!doingcache) { 485 cnp->cn_flags &= ~MAKEENTRY; 486 return (0); 487 } 488 retry: 489 CACHE_RLOCK(); 490 wlocked = 0; 491 numcalls++; 492 error = 0; 493 494 retry_wlocked: 495 if (cnp->cn_nameptr[0] == '.') { 496 if (cnp->cn_namelen == 1) { 497 *vpp = dvp; 498 CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .", 499 dvp, cnp->cn_nameptr); 500 dothits++; 501 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ".", *vpp); 502 if (tsp != NULL) 503 timespecclear(tsp); 504 if (ticksp != NULL) 505 *ticksp = ticks; 506 goto success; 507 } 508 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 509 dotdothits++; 510 if (dvp->v_cache_dd == NULL) { 511 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, 512 "..", NULL); 513 goto unlock; 514 } 515 if ((cnp->cn_flags & MAKEENTRY) == 0) { 516 if (!wlocked && !CACHE_UPGRADE_LOCK()) 517 goto wlock; 518 if (dvp->v_cache_dd->nc_flag & NCF_ISDOTDOT) 519 cache_zap(dvp->v_cache_dd); 520 dvp->v_cache_dd = NULL; 521 CACHE_WUNLOCK(); 522 return (0); 523 } 524 ncp = dvp->v_cache_dd; 525 if (ncp->nc_flag & NCF_ISDOTDOT) 526 *vpp = ncp->nc_vp; 527 else 528 *vpp = ncp->nc_dvp; 529 /* Return failure if negative entry was found. */ 530 if (*vpp == NULL) 531 goto negative_success; 532 CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..", 533 dvp, cnp->cn_nameptr, *vpp); 534 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, "..", 535 *vpp); 536 cache_out_ts(ncp, tsp, ticksp); 537 if ((ncp->nc_flag & (NCF_ISDOTDOT | NCF_DTS)) == 538 NCF_DTS && tsp != NULL) 539 *tsp = ((struct namecache_ts *)ncp)-> 540 nc_dotdottime; 541 goto success; 542 } 543 } 544 545 hash = fnv_32_buf(cnp->cn_nameptr, cnp->cn_namelen, FNV1_32_INIT); 546 hash = fnv_32_buf(&dvp, sizeof(dvp), hash); 547 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 548 numchecks++; 549 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 550 !bcmp(nc_get_name(ncp), cnp->cn_nameptr, ncp->nc_nlen)) 551 break; 552 } 553 554 /* We failed to find an entry */ 555 if (ncp == NULL) { 556 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr, 557 NULL); 558 if ((cnp->cn_flags & MAKEENTRY) == 0) { 559 nummisszap++; 560 } else { 561 nummiss++; 562 } 563 nchstats.ncs_miss++; 564 goto unlock; 565 } 566 567 /* We don't want to have an entry, so dump it */ 568 if ((cnp->cn_flags & MAKEENTRY) == 0) { 569 numposzaps++; 570 nchstats.ncs_badhits++; 571 if (!wlocked && !CACHE_UPGRADE_LOCK()) 572 goto wlock; 573 cache_zap(ncp); 574 CACHE_WUNLOCK(); 575 return (0); 576 } 577 578 /* We found a "positive" match, return the vnode */ 579 if (ncp->nc_vp) { 580 numposhits++; 581 nchstats.ncs_goodhits++; 582 *vpp = ncp->nc_vp; 583 CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p", 584 dvp, cnp->cn_nameptr, *vpp, ncp); 585 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, nc_get_name(ncp), 586 *vpp); 587 cache_out_ts(ncp, tsp, ticksp); 588 goto success; 589 } 590 591 negative_success: 592 /* We found a negative match, and want to create it, so purge */ 593 if (cnp->cn_nameiop == CREATE) { 594 numnegzaps++; 595 nchstats.ncs_badhits++; 596 if (!wlocked && !CACHE_UPGRADE_LOCK()) 597 goto wlock; 598 cache_zap(ncp); 599 CACHE_WUNLOCK(); 600 return (0); 601 } 602 603 if (!wlocked && !CACHE_UPGRADE_LOCK()) 604 goto wlock; 605 numneghits++; 606 /* 607 * We found a "negative" match, so we shift it to the end of 608 * the "negative" cache entries queue to satisfy LRU. Also, 609 * check to see if the entry is a whiteout; indicate this to 610 * the componentname, if so. 611 */ 612 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 613 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 614 nchstats.ncs_neghits++; 615 if (ncp->nc_flag & NCF_WHITE) 616 cnp->cn_flags |= ISWHITEOUT; 617 SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp, 618 nc_get_name(ncp)); 619 cache_out_ts(ncp, tsp, ticksp); 620 CACHE_WUNLOCK(); 621 return (ENOENT); 622 623 wlock: 624 /* 625 * We need to update the cache after our lookup, so upgrade to 626 * a write lock and retry the operation. 627 */ 628 CACHE_RUNLOCK(); 629 CACHE_WLOCK(); 630 numupgrades++; 631 wlocked = 1; 632 goto retry_wlocked; 633 634 success: 635 /* 636 * On success we return a locked and ref'd vnode as per the lookup 637 * protocol. 638 */ 639 if (dvp == *vpp) { /* lookup on "." */ 640 VREF(*vpp); 641 if (wlocked) 642 CACHE_WUNLOCK(); 643 else 644 CACHE_RUNLOCK(); 645 /* 646 * When we lookup "." we still can be asked to lock it 647 * differently... 648 */ 649 ltype = cnp->cn_lkflags & LK_TYPE_MASK; 650 if (ltype != VOP_ISLOCKED(*vpp)) { 651 if (ltype == LK_EXCLUSIVE) { 652 vn_lock(*vpp, LK_UPGRADE | LK_RETRY); 653 if ((*vpp)->v_iflag & VI_DOOMED) { 654 /* forced unmount */ 655 vrele(*vpp); 656 *vpp = NULL; 657 return (ENOENT); 658 } 659 } else 660 vn_lock(*vpp, LK_DOWNGRADE | LK_RETRY); 661 } 662 return (-1); 663 } 664 ltype = 0; /* silence gcc warning */ 665 if (cnp->cn_flags & ISDOTDOT) { 666 ltype = VOP_ISLOCKED(dvp); 667 VOP_UNLOCK(dvp, 0); 668 } 669 vhold(*vpp); 670 if (wlocked) 671 CACHE_WUNLOCK(); 672 else 673 CACHE_RUNLOCK(); 674 error = vget(*vpp, cnp->cn_lkflags | LK_VNHELD, cnp->cn_thread); 675 if (cnp->cn_flags & ISDOTDOT) { 676 vn_lock(dvp, ltype | LK_RETRY); 677 if (dvp->v_iflag & VI_DOOMED) { 678 if (error == 0) 679 vput(*vpp); 680 *vpp = NULL; 681 return (ENOENT); 682 } 683 } 684 if (error) { 685 *vpp = NULL; 686 goto retry; 687 } 688 if ((cnp->cn_flags & ISLASTCN) && 689 (cnp->cn_lkflags & LK_TYPE_MASK) == LK_EXCLUSIVE) { 690 ASSERT_VOP_ELOCKED(*vpp, "cache_lookup"); 691 } 692 return (-1); 693 694 unlock: 695 if (wlocked) 696 CACHE_WUNLOCK(); 697 else 698 CACHE_RUNLOCK(); 699 return (0); 700 } 701 702 /* 703 * Add an entry to the cache. 704 */ 705 void 706 cache_enter_time(dvp, vp, cnp, tsp, dtsp) 707 struct vnode *dvp; 708 struct vnode *vp; 709 struct componentname *cnp; 710 struct timespec *tsp; 711 struct timespec *dtsp; 712 { 713 struct namecache *ncp, *n2; 714 struct namecache_ts *n3; 715 struct nchashhead *ncpp; 716 uint32_t hash; 717 int flag; 718 int hold; 719 int zap; 720 int len; 721 722 CTR3(KTR_VFS, "cache_enter(%p, %p, %s)", dvp, vp, cnp->cn_nameptr); 723 VNASSERT(vp == NULL || (vp->v_iflag & VI_DOOMED) == 0, vp, 724 ("cache_enter: Adding a doomed vnode")); 725 VNASSERT(dvp == NULL || (dvp->v_iflag & VI_DOOMED) == 0, dvp, 726 ("cache_enter: Doomed vnode used as src")); 727 728 if (!doingcache) 729 return; 730 731 /* 732 * Avoid blowout in namecache entries. 733 */ 734 if (numcache >= desiredvnodes * ncsizefactor) 735 return; 736 737 flag = 0; 738 if (cnp->cn_nameptr[0] == '.') { 739 if (cnp->cn_namelen == 1) 740 return; 741 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 742 CACHE_WLOCK(); 743 /* 744 * If dotdot entry already exists, just retarget it 745 * to new parent vnode, otherwise continue with new 746 * namecache entry allocation. 747 */ 748 if ((ncp = dvp->v_cache_dd) != NULL && 749 ncp->nc_flag & NCF_ISDOTDOT) { 750 KASSERT(ncp->nc_dvp == dvp, 751 ("wrong isdotdot parent")); 752 if (ncp->nc_vp != NULL) { 753 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, 754 ncp, nc_dst); 755 } else { 756 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 757 numneg--; 758 } 759 if (vp != NULL) { 760 TAILQ_INSERT_HEAD(&vp->v_cache_dst, 761 ncp, nc_dst); 762 } else { 763 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 764 numneg++; 765 } 766 ncp->nc_vp = vp; 767 CACHE_WUNLOCK(); 768 return; 769 } 770 dvp->v_cache_dd = NULL; 771 SDT_PROBE3(vfs, namecache, enter, done, dvp, "..", vp); 772 CACHE_WUNLOCK(); 773 flag = NCF_ISDOTDOT; 774 } 775 } 776 777 hold = 0; 778 zap = 0; 779 780 /* 781 * Calculate the hash key and setup as much of the new 782 * namecache entry as possible before acquiring the lock. 783 */ 784 ncp = cache_alloc(cnp->cn_namelen, tsp != NULL); 785 ncp->nc_vp = vp; 786 ncp->nc_dvp = dvp; 787 ncp->nc_flag = flag; 788 if (tsp != NULL) { 789 n3 = (struct namecache_ts *)ncp; 790 n3->nc_time = *tsp; 791 n3->nc_ticks = ticks; 792 n3->nc_flag |= NCF_TS; 793 if (dtsp != NULL) { 794 n3->nc_dotdottime = *dtsp; 795 n3->nc_flag |= NCF_DTS; 796 } 797 } 798 len = ncp->nc_nlen = cnp->cn_namelen; 799 hash = fnv_32_buf(cnp->cn_nameptr, len, FNV1_32_INIT); 800 strlcpy(nc_get_name(ncp), cnp->cn_nameptr, len + 1); 801 hash = fnv_32_buf(&dvp, sizeof(dvp), hash); 802 CACHE_WLOCK(); 803 804 /* 805 * See if this vnode or negative entry is already in the cache 806 * with this name. This can happen with concurrent lookups of 807 * the same path name. 808 */ 809 ncpp = NCHHASH(hash); 810 LIST_FOREACH(n2, ncpp, nc_hash) { 811 if (n2->nc_dvp == dvp && 812 n2->nc_nlen == cnp->cn_namelen && 813 !bcmp(nc_get_name(n2), cnp->cn_nameptr, n2->nc_nlen)) { 814 if (tsp != NULL) { 815 KASSERT((n2->nc_flag & NCF_TS) != 0, 816 ("no NCF_TS")); 817 n3 = (struct namecache_ts *)n2; 818 n3->nc_time = 819 ((struct namecache_ts *)ncp)->nc_time; 820 n3->nc_ticks = 821 ((struct namecache_ts *)ncp)->nc_ticks; 822 if (dtsp != NULL) { 823 n3->nc_dotdottime = 824 ((struct namecache_ts *)ncp)-> 825 nc_dotdottime; 826 n3->nc_flag |= NCF_DTS; 827 } 828 } 829 CACHE_WUNLOCK(); 830 cache_free(ncp); 831 return; 832 } 833 } 834 835 if (flag == NCF_ISDOTDOT) { 836 /* 837 * See if we are trying to add .. entry, but some other lookup 838 * has populated v_cache_dd pointer already. 839 */ 840 if (dvp->v_cache_dd != NULL) { 841 CACHE_WUNLOCK(); 842 cache_free(ncp); 843 return; 844 } 845 KASSERT(vp == NULL || vp->v_type == VDIR, 846 ("wrong vnode type %p", vp)); 847 dvp->v_cache_dd = ncp; 848 } 849 850 numcache++; 851 if (!vp) { 852 numneg++; 853 if (cnp->cn_flags & ISWHITEOUT) 854 ncp->nc_flag |= NCF_WHITE; 855 } else if (vp->v_type == VDIR) { 856 if (flag != NCF_ISDOTDOT) { 857 /* 858 * For this case, the cache entry maps both the 859 * directory name in it and the name ".." for the 860 * directory's parent. 861 */ 862 if ((n2 = vp->v_cache_dd) != NULL && 863 (n2->nc_flag & NCF_ISDOTDOT) != 0) 864 cache_zap(n2); 865 vp->v_cache_dd = ncp; 866 } 867 } else { 868 vp->v_cache_dd = NULL; 869 } 870 871 /* 872 * Insert the new namecache entry into the appropriate chain 873 * within the cache entries table. 874 */ 875 LIST_INSERT_HEAD(ncpp, ncp, nc_hash); 876 if (flag != NCF_ISDOTDOT) { 877 if (LIST_EMPTY(&dvp->v_cache_src)) { 878 hold = 1; 879 numcachehv++; 880 } 881 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); 882 } 883 884 /* 885 * If the entry is "negative", we place it into the 886 * "negative" cache queue, otherwise, we place it into the 887 * destination vnode's cache entries queue. 888 */ 889 if (vp) { 890 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); 891 SDT_PROBE3(vfs, namecache, enter, done, dvp, nc_get_name(ncp), 892 vp); 893 } else { 894 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 895 SDT_PROBE2(vfs, namecache, enter_negative, done, dvp, 896 nc_get_name(ncp)); 897 } 898 if (numneg * ncnegfactor > numcache) { 899 ncp = TAILQ_FIRST(&ncneg); 900 KASSERT(ncp->nc_vp == NULL, ("ncp %p vp %p on ncneg", 901 ncp, ncp->nc_vp)); 902 zap = 1; 903 } 904 if (hold) 905 vhold(dvp); 906 if (zap) 907 cache_zap(ncp); 908 CACHE_WUNLOCK(); 909 } 910 911 /* 912 * Name cache initialization, from vfs_init() when we are booting 913 */ 914 static void 915 nchinit(void *dummy __unused) 916 { 917 918 TAILQ_INIT(&ncneg); 919 920 cache_zone_small = uma_zcreate("S VFS Cache", 921 sizeof(struct namecache) + CACHE_PATH_CUTOFF + 1, 922 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 923 cache_zone_small_ts = uma_zcreate("STS VFS Cache", 924 sizeof(struct namecache_ts) + CACHE_PATH_CUTOFF + 1, 925 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 926 cache_zone_large = uma_zcreate("L VFS Cache", 927 sizeof(struct namecache) + NAME_MAX + 1, 928 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 929 cache_zone_large_ts = uma_zcreate("LTS VFS Cache", 930 sizeof(struct namecache_ts) + NAME_MAX + 1, 931 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 932 933 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash); 934 } 935 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL); 936 937 void 938 cache_changesize(int newmaxvnodes) 939 { 940 struct nchashhead *new_nchashtbl, *old_nchashtbl; 941 u_long new_nchash, old_nchash; 942 struct namecache *ncp; 943 uint32_t hash; 944 int i; 945 946 new_nchashtbl = hashinit(newmaxvnodes * 2, M_VFSCACHE, &new_nchash); 947 /* If same hash table size, nothing to do */ 948 if (nchash == new_nchash) { 949 free(new_nchashtbl, M_VFSCACHE); 950 return; 951 } 952 /* 953 * Move everything from the old hash table to the new table. 954 * None of the namecache entries in the table can be removed 955 * because to do so, they have to be removed from the hash table. 956 */ 957 CACHE_WLOCK(); 958 old_nchashtbl = nchashtbl; 959 old_nchash = nchash; 960 nchashtbl = new_nchashtbl; 961 nchash = new_nchash; 962 for (i = 0; i <= old_nchash; i++) { 963 while ((ncp = LIST_FIRST(&old_nchashtbl[i])) != NULL) { 964 hash = fnv_32_buf(nc_get_name(ncp), ncp->nc_nlen, 965 FNV1_32_INIT); 966 hash = fnv_32_buf(&ncp->nc_dvp, sizeof(ncp->nc_dvp), 967 hash); 968 LIST_REMOVE(ncp, nc_hash); 969 LIST_INSERT_HEAD(NCHHASH(hash), ncp, nc_hash); 970 } 971 } 972 CACHE_WUNLOCK(); 973 free(old_nchashtbl, M_VFSCACHE); 974 } 975 976 /* 977 * Invalidate all entries to a particular vnode. 978 */ 979 void 980 cache_purge(vp) 981 struct vnode *vp; 982 { 983 984 CTR1(KTR_VFS, "cache_purge(%p)", vp); 985 SDT_PROBE1(vfs, namecache, purge, done, vp); 986 CACHE_WLOCK(); 987 while (!LIST_EMPTY(&vp->v_cache_src)) 988 cache_zap(LIST_FIRST(&vp->v_cache_src)); 989 while (!TAILQ_EMPTY(&vp->v_cache_dst)) 990 cache_zap(TAILQ_FIRST(&vp->v_cache_dst)); 991 if (vp->v_cache_dd != NULL) { 992 KASSERT(vp->v_cache_dd->nc_flag & NCF_ISDOTDOT, 993 ("lost dotdot link")); 994 cache_zap(vp->v_cache_dd); 995 } 996 KASSERT(vp->v_cache_dd == NULL, ("incomplete purge")); 997 CACHE_WUNLOCK(); 998 } 999 1000 /* 1001 * Invalidate all negative entries for a particular directory vnode. 1002 */ 1003 void 1004 cache_purge_negative(vp) 1005 struct vnode *vp; 1006 { 1007 struct namecache *cp, *ncp; 1008 1009 CTR1(KTR_VFS, "cache_purge_negative(%p)", vp); 1010 SDT_PROBE1(vfs, namecache, purge_negative, done, vp); 1011 CACHE_WLOCK(); 1012 LIST_FOREACH_SAFE(cp, &vp->v_cache_src, nc_src, ncp) { 1013 if (cp->nc_vp == NULL) 1014 cache_zap(cp); 1015 } 1016 CACHE_WUNLOCK(); 1017 } 1018 1019 /* 1020 * Flush all entries referencing a particular filesystem. 1021 */ 1022 void 1023 cache_purgevfs(mp) 1024 struct mount *mp; 1025 { 1026 struct nchashhead *ncpp; 1027 struct namecache *ncp, *nnp; 1028 1029 /* Scan hash tables for applicable entries */ 1030 SDT_PROBE1(vfs, namecache, purgevfs, done, mp); 1031 CACHE_WLOCK(); 1032 for (ncpp = &nchashtbl[nchash]; ncpp >= nchashtbl; ncpp--) { 1033 LIST_FOREACH_SAFE(ncp, ncpp, nc_hash, nnp) { 1034 if (ncp->nc_dvp->v_mount == mp) 1035 cache_zap(ncp); 1036 } 1037 } 1038 CACHE_WUNLOCK(); 1039 } 1040 1041 /* 1042 * Perform canonical checks and cache lookup and pass on to filesystem 1043 * through the vop_cachedlookup only if needed. 1044 */ 1045 1046 int 1047 vfs_cache_lookup(ap) 1048 struct vop_lookup_args /* { 1049 struct vnode *a_dvp; 1050 struct vnode **a_vpp; 1051 struct componentname *a_cnp; 1052 } */ *ap; 1053 { 1054 struct vnode *dvp; 1055 int error; 1056 struct vnode **vpp = ap->a_vpp; 1057 struct componentname *cnp = ap->a_cnp; 1058 struct ucred *cred = cnp->cn_cred; 1059 int flags = cnp->cn_flags; 1060 struct thread *td = cnp->cn_thread; 1061 1062 *vpp = NULL; 1063 dvp = ap->a_dvp; 1064 1065 if (dvp->v_type != VDIR) 1066 return (ENOTDIR); 1067 1068 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && 1069 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 1070 return (EROFS); 1071 1072 error = VOP_ACCESS(dvp, VEXEC, cred, td); 1073 if (error) 1074 return (error); 1075 1076 error = cache_lookup(dvp, vpp, cnp, NULL, NULL); 1077 if (error == 0) 1078 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); 1079 if (error == -1) 1080 return (0); 1081 return (error); 1082 } 1083 1084 /* 1085 * XXX All of these sysctls would probably be more productive dead. 1086 */ 1087 static int disablecwd; 1088 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, 1089 "Disable the getcwd syscall"); 1090 1091 /* Implementation of the getcwd syscall. */ 1092 int 1093 sys___getcwd(td, uap) 1094 struct thread *td; 1095 struct __getcwd_args *uap; 1096 { 1097 1098 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen, 1099 MAXPATHLEN)); 1100 } 1101 1102 int 1103 kern___getcwd(struct thread *td, char *buf, enum uio_seg bufseg, u_int buflen, 1104 u_int path_max) 1105 { 1106 char *bp, *tmpbuf; 1107 struct filedesc *fdp; 1108 struct vnode *cdir, *rdir; 1109 int error; 1110 1111 if (disablecwd) 1112 return (ENODEV); 1113 if (buflen < 2) 1114 return (EINVAL); 1115 if (buflen > path_max) 1116 buflen = path_max; 1117 1118 tmpbuf = malloc(buflen, M_TEMP, M_WAITOK); 1119 fdp = td->td_proc->p_fd; 1120 FILEDESC_SLOCK(fdp); 1121 cdir = fdp->fd_cdir; 1122 VREF(cdir); 1123 rdir = fdp->fd_rdir; 1124 VREF(rdir); 1125 FILEDESC_SUNLOCK(fdp); 1126 error = vn_fullpath1(td, cdir, rdir, tmpbuf, &bp, buflen); 1127 vrele(rdir); 1128 vrele(cdir); 1129 1130 if (!error) { 1131 if (bufseg == UIO_SYSSPACE) 1132 bcopy(bp, buf, strlen(bp) + 1); 1133 else 1134 error = copyout(bp, buf, strlen(bp) + 1); 1135 #ifdef KTRACE 1136 if (KTRPOINT(curthread, KTR_NAMEI)) 1137 ktrnamei(bp); 1138 #endif 1139 } 1140 free(tmpbuf, M_TEMP); 1141 return (error); 1142 } 1143 1144 /* 1145 * Thus begins the fullpath magic. 1146 */ 1147 1148 #undef STATNODE 1149 #define STATNODE(name, descr) \ 1150 static u_int name; \ 1151 SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, descr) 1152 1153 static int disablefullpath; 1154 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0, 1155 "Disable the vn_fullpath function"); 1156 1157 /* These count for kern___getcwd(), too. */ 1158 STATNODE(numfullpathcalls, "Number of fullpath search calls"); 1159 STATNODE(numfullpathfail1, "Number of fullpath search errors (ENOTDIR)"); 1160 STATNODE(numfullpathfail2, 1161 "Number of fullpath search errors (VOP_VPTOCNP failures)"); 1162 STATNODE(numfullpathfail4, "Number of fullpath search errors (ENOMEM)"); 1163 STATNODE(numfullpathfound, "Number of successful fullpath calls"); 1164 1165 /* 1166 * Retrieve the full filesystem path that correspond to a vnode from the name 1167 * cache (if available) 1168 */ 1169 int 1170 vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf) 1171 { 1172 char *buf; 1173 struct filedesc *fdp; 1174 struct vnode *rdir; 1175 int error; 1176 1177 if (disablefullpath) 1178 return (ENODEV); 1179 if (vn == NULL) 1180 return (EINVAL); 1181 1182 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 1183 fdp = td->td_proc->p_fd; 1184 FILEDESC_SLOCK(fdp); 1185 rdir = fdp->fd_rdir; 1186 VREF(rdir); 1187 FILEDESC_SUNLOCK(fdp); 1188 error = vn_fullpath1(td, vn, rdir, buf, retbuf, MAXPATHLEN); 1189 vrele(rdir); 1190 1191 if (!error) 1192 *freebuf = buf; 1193 else 1194 free(buf, M_TEMP); 1195 return (error); 1196 } 1197 1198 /* 1199 * This function is similar to vn_fullpath, but it attempts to lookup the 1200 * pathname relative to the global root mount point. This is required for the 1201 * auditing sub-system, as audited pathnames must be absolute, relative to the 1202 * global root mount point. 1203 */ 1204 int 1205 vn_fullpath_global(struct thread *td, struct vnode *vn, 1206 char **retbuf, char **freebuf) 1207 { 1208 char *buf; 1209 int error; 1210 1211 if (disablefullpath) 1212 return (ENODEV); 1213 if (vn == NULL) 1214 return (EINVAL); 1215 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 1216 error = vn_fullpath1(td, vn, rootvnode, buf, retbuf, MAXPATHLEN); 1217 if (!error) 1218 *freebuf = buf; 1219 else 1220 free(buf, M_TEMP); 1221 return (error); 1222 } 1223 1224 int 1225 vn_vptocnp(struct vnode **vp, struct ucred *cred, char *buf, u_int *buflen) 1226 { 1227 int error; 1228 1229 CACHE_RLOCK(); 1230 error = vn_vptocnp_locked(vp, cred, buf, buflen); 1231 if (error == 0) 1232 CACHE_RUNLOCK(); 1233 return (error); 1234 } 1235 1236 static int 1237 vn_vptocnp_locked(struct vnode **vp, struct ucred *cred, char *buf, 1238 u_int *buflen) 1239 { 1240 struct vnode *dvp; 1241 struct namecache *ncp; 1242 int error; 1243 1244 TAILQ_FOREACH(ncp, &((*vp)->v_cache_dst), nc_dst) { 1245 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 1246 break; 1247 } 1248 if (ncp != NULL) { 1249 if (*buflen < ncp->nc_nlen) { 1250 CACHE_RUNLOCK(); 1251 vrele(*vp); 1252 numfullpathfail4++; 1253 error = ENOMEM; 1254 SDT_PROBE3(vfs, namecache, fullpath, return, error, 1255 vp, NULL); 1256 return (error); 1257 } 1258 *buflen -= ncp->nc_nlen; 1259 memcpy(buf + *buflen, nc_get_name(ncp), ncp->nc_nlen); 1260 SDT_PROBE3(vfs, namecache, fullpath, hit, ncp->nc_dvp, 1261 nc_get_name(ncp), vp); 1262 dvp = *vp; 1263 *vp = ncp->nc_dvp; 1264 vref(*vp); 1265 CACHE_RUNLOCK(); 1266 vrele(dvp); 1267 CACHE_RLOCK(); 1268 return (0); 1269 } 1270 SDT_PROBE1(vfs, namecache, fullpath, miss, vp); 1271 1272 CACHE_RUNLOCK(); 1273 vn_lock(*vp, LK_SHARED | LK_RETRY); 1274 error = VOP_VPTOCNP(*vp, &dvp, cred, buf, buflen); 1275 vput(*vp); 1276 if (error) { 1277 numfullpathfail2++; 1278 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); 1279 return (error); 1280 } 1281 1282 *vp = dvp; 1283 CACHE_RLOCK(); 1284 if (dvp->v_iflag & VI_DOOMED) { 1285 /* forced unmount */ 1286 CACHE_RUNLOCK(); 1287 vrele(dvp); 1288 error = ENOENT; 1289 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); 1290 return (error); 1291 } 1292 /* 1293 * *vp has its use count incremented still. 1294 */ 1295 1296 return (0); 1297 } 1298 1299 /* 1300 * The magic behind kern___getcwd() and vn_fullpath(). 1301 */ 1302 static int 1303 vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 1304 char *buf, char **retbuf, u_int buflen) 1305 { 1306 int error, slash_prefixed; 1307 #ifdef KDTRACE_HOOKS 1308 struct vnode *startvp = vp; 1309 #endif 1310 struct vnode *vp1; 1311 1312 buflen--; 1313 buf[buflen] = '\0'; 1314 error = 0; 1315 slash_prefixed = 0; 1316 1317 SDT_PROBE1(vfs, namecache, fullpath, entry, vp); 1318 numfullpathcalls++; 1319 vref(vp); 1320 CACHE_RLOCK(); 1321 if (vp->v_type != VDIR) { 1322 error = vn_vptocnp_locked(&vp, td->td_ucred, buf, &buflen); 1323 if (error) 1324 return (error); 1325 if (buflen == 0) { 1326 CACHE_RUNLOCK(); 1327 vrele(vp); 1328 return (ENOMEM); 1329 } 1330 buf[--buflen] = '/'; 1331 slash_prefixed = 1; 1332 } 1333 while (vp != rdir && vp != rootvnode) { 1334 if (vp->v_vflag & VV_ROOT) { 1335 if (vp->v_iflag & VI_DOOMED) { /* forced unmount */ 1336 CACHE_RUNLOCK(); 1337 vrele(vp); 1338 error = ENOENT; 1339 SDT_PROBE3(vfs, namecache, fullpath, return, 1340 error, vp, NULL); 1341 break; 1342 } 1343 vp1 = vp->v_mount->mnt_vnodecovered; 1344 vref(vp1); 1345 CACHE_RUNLOCK(); 1346 vrele(vp); 1347 vp = vp1; 1348 CACHE_RLOCK(); 1349 continue; 1350 } 1351 if (vp->v_type != VDIR) { 1352 CACHE_RUNLOCK(); 1353 vrele(vp); 1354 numfullpathfail1++; 1355 error = ENOTDIR; 1356 SDT_PROBE3(vfs, namecache, fullpath, return, 1357 error, vp, NULL); 1358 break; 1359 } 1360 error = vn_vptocnp_locked(&vp, td->td_ucred, buf, &buflen); 1361 if (error) 1362 break; 1363 if (buflen == 0) { 1364 CACHE_RUNLOCK(); 1365 vrele(vp); 1366 error = ENOMEM; 1367 SDT_PROBE3(vfs, namecache, fullpath, return, error, 1368 startvp, NULL); 1369 break; 1370 } 1371 buf[--buflen] = '/'; 1372 slash_prefixed = 1; 1373 } 1374 if (error) 1375 return (error); 1376 if (!slash_prefixed) { 1377 if (buflen == 0) { 1378 CACHE_RUNLOCK(); 1379 vrele(vp); 1380 numfullpathfail4++; 1381 SDT_PROBE3(vfs, namecache, fullpath, return, ENOMEM, 1382 startvp, NULL); 1383 return (ENOMEM); 1384 } 1385 buf[--buflen] = '/'; 1386 } 1387 numfullpathfound++; 1388 CACHE_RUNLOCK(); 1389 vrele(vp); 1390 1391 SDT_PROBE3(vfs, namecache, fullpath, return, 0, startvp, buf + buflen); 1392 *retbuf = buf + buflen; 1393 return (0); 1394 } 1395 1396 struct vnode * 1397 vn_dir_dd_ino(struct vnode *vp) 1398 { 1399 struct namecache *ncp; 1400 struct vnode *ddvp; 1401 1402 ASSERT_VOP_LOCKED(vp, "vn_dir_dd_ino"); 1403 CACHE_RLOCK(); 1404 TAILQ_FOREACH(ncp, &(vp->v_cache_dst), nc_dst) { 1405 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) 1406 continue; 1407 ddvp = ncp->nc_dvp; 1408 vhold(ddvp); 1409 CACHE_RUNLOCK(); 1410 if (vget(ddvp, LK_SHARED | LK_NOWAIT | LK_VNHELD, curthread)) 1411 return (NULL); 1412 return (ddvp); 1413 } 1414 CACHE_RUNLOCK(); 1415 return (NULL); 1416 } 1417 1418 int 1419 vn_commname(struct vnode *vp, char *buf, u_int buflen) 1420 { 1421 struct namecache *ncp; 1422 int l; 1423 1424 CACHE_RLOCK(); 1425 TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst) 1426 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 1427 break; 1428 if (ncp == NULL) { 1429 CACHE_RUNLOCK(); 1430 return (ENOENT); 1431 } 1432 l = min(ncp->nc_nlen, buflen - 1); 1433 memcpy(buf, nc_get_name(ncp), l); 1434 CACHE_RUNLOCK(); 1435 buf[l] = '\0'; 1436 return (0); 1437 } 1438 1439 /* ABI compat shims for old kernel modules. */ 1440 #undef cache_enter 1441 1442 void cache_enter(struct vnode *dvp, struct vnode *vp, 1443 struct componentname *cnp); 1444 1445 void 1446 cache_enter(struct vnode *dvp, struct vnode *vp, struct componentname *cnp) 1447 { 1448 1449 cache_enter_time(dvp, vp, cnp, NULL, NULL); 1450 } 1451 1452 /* 1453 * This function updates path string to vnode's full global path 1454 * and checks the size of the new path string against the pathlen argument. 1455 * 1456 * Requires a locked, referenced vnode. 1457 * Vnode is re-locked on success or ENODEV, otherwise unlocked. 1458 * 1459 * If sysctl debug.disablefullpath is set, ENODEV is returned, 1460 * vnode is left locked and path remain untouched. 1461 * 1462 * If vp is a directory, the call to vn_fullpath_global() always succeeds 1463 * because it falls back to the ".." lookup if the namecache lookup fails. 1464 */ 1465 int 1466 vn_path_to_global_path(struct thread *td, struct vnode *vp, char *path, 1467 u_int pathlen) 1468 { 1469 struct nameidata nd; 1470 struct vnode *vp1; 1471 char *rpath, *fbuf; 1472 int error; 1473 1474 ASSERT_VOP_ELOCKED(vp, __func__); 1475 1476 /* Return ENODEV if sysctl debug.disablefullpath==1 */ 1477 if (disablefullpath) 1478 return (ENODEV); 1479 1480 /* Construct global filesystem path from vp. */ 1481 VOP_UNLOCK(vp, 0); 1482 error = vn_fullpath_global(td, vp, &rpath, &fbuf); 1483 1484 if (error != 0) { 1485 vrele(vp); 1486 return (error); 1487 } 1488 1489 if (strlen(rpath) >= pathlen) { 1490 vrele(vp); 1491 error = ENAMETOOLONG; 1492 goto out; 1493 } 1494 1495 /* 1496 * Re-lookup the vnode by path to detect a possible rename. 1497 * As a side effect, the vnode is relocked. 1498 * If vnode was renamed, return ENOENT. 1499 */ 1500 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1, 1501 UIO_SYSSPACE, path, td); 1502 error = namei(&nd); 1503 if (error != 0) { 1504 vrele(vp); 1505 goto out; 1506 } 1507 NDFREE(&nd, NDF_ONLY_PNBUF); 1508 vp1 = nd.ni_vp; 1509 vrele(vp); 1510 if (vp1 == vp) 1511 strcpy(path, rpath); 1512 else { 1513 vput(vp1); 1514 error = ENOENT; 1515 } 1516 1517 out: 1518 free(fbuf, M_TEMP); 1519 return (error); 1520 } 1521