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/10.3/sys/kern/vfs_cache.c 289798 2015-10-23 07:40:43Z avg $"); 37 38 #include "opt_kdtrace.h" 39 #include "opt_ktrace.h" 40 41 #include <sys/param.h> 42 #include <sys/systm.h> 43 #include <sys/filedesc.h> 44 #include <sys/fnv_hash.h> 45 #include <sys/kernel.h> 46 #include <sys/lock.h> 47 #include <sys/malloc.h> 48 #include <sys/fcntl.h> 49 #include <sys/mount.h> 50 #include <sys/namei.h> 51 #include <sys/proc.h> 52 #include <sys/rwlock.h> 53 #include <sys/sdt.h> 54 #include <sys/syscallsubr.h> 55 #include <sys/sysctl.h> 56 #include <sys/sysproto.h> 57 #include <sys/vnode.h> 58 #ifdef KTRACE 59 #include <sys/ktrace.h> 60 #endif 61 62 #include <vm/uma.h> 63 64 SDT_PROVIDER_DECLARE(vfs); 65 SDT_PROBE_DEFINE3(vfs, namecache, enter, done, "struct vnode *", "char *", 66 "struct vnode *"); 67 SDT_PROBE_DEFINE2(vfs, namecache, enter_negative, done, "struct vnode *", 68 "char *"); 69 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, entry, "struct vnode *"); 70 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, hit, "struct vnode *", 71 "char *", "struct vnode *"); 72 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, miss, "struct vnode *"); 73 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, return, "int", 74 "struct vnode *", "char *"); 75 SDT_PROBE_DEFINE3(vfs, namecache, lookup, hit, "struct vnode *", "char *", 76 "struct vnode *"); 77 SDT_PROBE_DEFINE2(vfs, namecache, lookup, hit__negative, 78 "struct vnode *", "char *"); 79 SDT_PROBE_DEFINE2(vfs, namecache, lookup, miss, "struct vnode *", 80 "char *"); 81 SDT_PROBE_DEFINE1(vfs, namecache, purge, done, "struct vnode *"); 82 SDT_PROBE_DEFINE1(vfs, namecache, purge_negative, done, "struct vnode *"); 83 SDT_PROBE_DEFINE1(vfs, namecache, purgevfs, done, "struct mount *"); 84 SDT_PROBE_DEFINE3(vfs, namecache, zap, done, "struct vnode *", "char *", 85 "struct vnode *"); 86 SDT_PROBE_DEFINE2(vfs, namecache, zap_negative, done, "struct vnode *", 87 "char *"); 88 89 /* 90 * This structure describes the elements in the cache of recent 91 * names looked up by namei. 92 */ 93 94 struct namecache { 95 LIST_ENTRY(namecache) nc_hash; /* hash chain */ 96 LIST_ENTRY(namecache) nc_src; /* source vnode list */ 97 TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */ 98 struct vnode *nc_dvp; /* vnode of parent of name */ 99 struct vnode *nc_vp; /* vnode the name refers to */ 100 u_char nc_flag; /* flag bits */ 101 u_char nc_nlen; /* length of name */ 102 char nc_name[0]; /* segment name + nul */ 103 }; 104 105 /* 106 * struct namecache_ts repeats struct namecache layout up to the 107 * nc_nlen member. 108 * struct namecache_ts is used in place of struct namecache when time(s) need 109 * to be stored. The nc_dotdottime field is used when a cache entry is mapping 110 * both a non-dotdot directory name plus dotdot for the directory's 111 * parent. 112 */ 113 struct namecache_ts { 114 LIST_ENTRY(namecache) nc_hash; /* hash chain */ 115 LIST_ENTRY(namecache) nc_src; /* source vnode list */ 116 TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */ 117 struct vnode *nc_dvp; /* vnode of parent of name */ 118 struct vnode *nc_vp; /* vnode the name refers to */ 119 u_char nc_flag; /* flag bits */ 120 u_char nc_nlen; /* length of name */ 121 struct timespec nc_time; /* timespec provided by fs */ 122 struct timespec nc_dotdottime; /* dotdot timespec provided by fs */ 123 int nc_ticks; /* ticks value when entry was added */ 124 char nc_name[0]; /* segment name + nul */ 125 }; 126 127 /* 128 * Flags in namecache.nc_flag 129 */ 130 #define NCF_WHITE 0x01 131 #define NCF_ISDOTDOT 0x02 132 #define NCF_TS 0x04 133 #define NCF_DTS 0x08 134 135 /* 136 * Name caching works as follows: 137 * 138 * Names found by directory scans are retained in a cache 139 * for future reference. It is managed LRU, so frequently 140 * used names will hang around. Cache is indexed by hash value 141 * obtained from (vp, name) where vp refers to the directory 142 * containing name. 143 * 144 * If it is a "negative" entry, (i.e. for a name that is known NOT to 145 * exist) the vnode pointer will be NULL. 146 * 147 * Upon reaching the last segment of a path, if the reference 148 * is for DELETE, or NOCACHE is set (rewrite), and the 149 * name is located in the cache, it will be dropped. 150 */ 151 152 /* 153 * Structures associated with name cacheing. 154 */ 155 #define NCHHASH(hash) \ 156 (&nchashtbl[(hash) & nchash]) 157 static LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */ 158 static TAILQ_HEAD(, namecache) ncneg; /* Hash Table */ 159 static u_long nchash; /* size of hash table */ 160 SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, 161 "Size of namecache hash table"); 162 static u_long ncnegfactor = 16; /* ratio of negative entries */ 163 SYSCTL_ULONG(_vfs, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, 164 "Ratio of negative namecache entries"); 165 static u_long numneg; /* number of negative entries allocated */ 166 SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, 167 "Number of negative entries in namecache"); 168 static u_long numcache; /* number of cache entries allocated */ 169 SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, 170 "Number of namecache entries"); 171 static u_long numcachehv; /* number of cache entries with vnodes held */ 172 SYSCTL_ULONG(_debug, OID_AUTO, numcachehv, CTLFLAG_RD, &numcachehv, 0, 173 "Number of namecache entries with vnodes held"); 174 static u_int ncsizefactor = 2; 175 SYSCTL_UINT(_vfs, OID_AUTO, ncsizefactor, CTLFLAG_RW, &ncsizefactor, 0, 176 "Size factor for namecache"); 177 178 struct nchstats nchstats; /* cache effectiveness statistics */ 179 180 static struct rwlock cache_lock; 181 RW_SYSINIT(vfscache, &cache_lock, "Name Cache"); 182 183 #define CACHE_UPGRADE_LOCK() rw_try_upgrade(&cache_lock) 184 #define CACHE_RLOCK() rw_rlock(&cache_lock) 185 #define CACHE_RUNLOCK() rw_runlock(&cache_lock) 186 #define CACHE_WLOCK() rw_wlock(&cache_lock) 187 #define CACHE_WUNLOCK() rw_wunlock(&cache_lock) 188 189 /* 190 * UMA zones for the VFS cache. 191 * 192 * The small cache is used for entries with short names, which are the 193 * most common. The large cache is used for entries which are too big to 194 * fit in the small cache. 195 */ 196 static uma_zone_t cache_zone_small; 197 static uma_zone_t cache_zone_small_ts; 198 static uma_zone_t cache_zone_large; 199 static uma_zone_t cache_zone_large_ts; 200 201 #define CACHE_PATH_CUTOFF 35 202 203 static struct namecache * 204 cache_alloc(int len, int ts) 205 { 206 207 if (len > CACHE_PATH_CUTOFF) { 208 if (ts) 209 return (uma_zalloc(cache_zone_large_ts, M_WAITOK)); 210 else 211 return (uma_zalloc(cache_zone_large, M_WAITOK)); 212 } 213 if (ts) 214 return (uma_zalloc(cache_zone_small_ts, M_WAITOK)); 215 else 216 return (uma_zalloc(cache_zone_small, M_WAITOK)); 217 } 218 219 static void 220 cache_free(struct namecache *ncp) 221 { 222 int ts; 223 224 if (ncp == NULL) 225 return; 226 ts = ncp->nc_flag & NCF_TS; 227 if (ncp->nc_nlen <= CACHE_PATH_CUTOFF) { 228 if (ts) 229 uma_zfree(cache_zone_small_ts, ncp); 230 else 231 uma_zfree(cache_zone_small, ncp); 232 } else if (ts) 233 uma_zfree(cache_zone_large_ts, ncp); 234 else 235 uma_zfree(cache_zone_large, ncp); 236 } 237 238 static char * 239 nc_get_name(struct namecache *ncp) 240 { 241 struct namecache_ts *ncp_ts; 242 243 if ((ncp->nc_flag & NCF_TS) == 0) 244 return (ncp->nc_name); 245 ncp_ts = (struct namecache_ts *)ncp; 246 return (ncp_ts->nc_name); 247 } 248 249 static void 250 cache_out_ts(struct namecache *ncp, struct timespec *tsp, int *ticksp) 251 { 252 253 KASSERT((ncp->nc_flag & NCF_TS) != 0 || 254 (tsp == NULL && ticksp == NULL), 255 ("No NCF_TS")); 256 257 if (tsp != NULL) 258 *tsp = ((struct namecache_ts *)ncp)->nc_time; 259 if (ticksp != NULL) 260 *ticksp = ((struct namecache_ts *)ncp)->nc_ticks; 261 } 262 263 static int doingcache = 1; /* 1 => enable the cache */ 264 SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0, 265 "VFS namecache enabled"); 266 267 /* Export size information to userland */ 268 SYSCTL_INT(_debug_sizeof, OID_AUTO, namecache, CTLFLAG_RD, SYSCTL_NULL_INT_PTR, 269 sizeof(struct namecache), "sizeof(struct namecache)"); 270 271 /* 272 * The new name cache statistics 273 */ 274 static SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, 275 "Name cache statistics"); 276 #define STATNODE(mode, name, var, descr) \ 277 SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, mode, var, 0, descr); 278 STATNODE(CTLFLAG_RD, numneg, &numneg, "Number of negative cache entries"); 279 STATNODE(CTLFLAG_RD, numcache, &numcache, "Number of cache entries"); 280 static u_long numcalls; STATNODE(CTLFLAG_RD, numcalls, &numcalls, 281 "Number of cache lookups"); 282 static u_long dothits; STATNODE(CTLFLAG_RD, dothits, &dothits, 283 "Number of '.' hits"); 284 static u_long dotdothits; STATNODE(CTLFLAG_RD, dotdothits, &dotdothits, 285 "Number of '..' hits"); 286 static u_long numchecks; STATNODE(CTLFLAG_RD, numchecks, &numchecks, 287 "Number of checks in lookup"); 288 static u_long nummiss; STATNODE(CTLFLAG_RD, nummiss, &nummiss, 289 "Number of cache misses"); 290 static u_long nummisszap; STATNODE(CTLFLAG_RD, nummisszap, &nummisszap, 291 "Number of cache misses we do not want to cache"); 292 static u_long numposzaps; STATNODE(CTLFLAG_RD, numposzaps, &numposzaps, 293 "Number of cache hits (positive) we do not want to cache"); 294 static u_long numposhits; STATNODE(CTLFLAG_RD, numposhits, &numposhits, 295 "Number of cache hits (positive)"); 296 static u_long numnegzaps; STATNODE(CTLFLAG_RD, numnegzaps, &numnegzaps, 297 "Number of cache hits (negative) we do not want to cache"); 298 static u_long numneghits; STATNODE(CTLFLAG_RD, numneghits, &numneghits, 299 "Number of cache hits (negative)"); 300 static u_long numupgrades; STATNODE(CTLFLAG_RD, numupgrades, &numupgrades, 301 "Number of updates of the cache after lookup (write lock + retry)"); 302 303 SYSCTL_OPAQUE(_vfs_cache, OID_AUTO, nchstats, CTLFLAG_RD | CTLFLAG_MPSAFE, 304 &nchstats, sizeof(nchstats), "LU", 305 "VFS cache effectiveness statistics"); 306 307 308 309 static void cache_zap(struct namecache *ncp); 310 static int vn_vptocnp_locked(struct vnode **vp, struct ucred *cred, char *buf, 311 u_int *buflen); 312 static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 313 char *buf, char **retbuf, u_int buflen); 314 315 static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); 316 317 #ifdef DIAGNOSTIC 318 /* 319 * Grab an atomic snapshot of the name cache hash chain lengths 320 */ 321 static SYSCTL_NODE(_debug, OID_AUTO, hashstat, CTLFLAG_RW, NULL, 322 "hash table stats"); 323 324 static int 325 sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS) 326 { 327 struct nchashhead *ncpp; 328 struct namecache *ncp; 329 int i, error, n_nchash, *cntbuf; 330 331 retry: 332 n_nchash = nchash + 1; /* nchash is max index, not count */ 333 if (!req->oldptr) 334 return SYSCTL_OUT(req, 0, n_nchash * sizeof(int)); 335 cntbuf = malloc(n_nchash * sizeof(int), M_TEMP, M_ZERO | M_WAITOK); 336 CACHE_RLOCK(); 337 if (n_nchash != nchash + 1) { 338 CACHE_RUNLOCK(); 339 free(cntbuf, M_TEMP); 340 goto retry; 341 } 342 /* Scan hash tables counting entries */ 343 for (ncpp = nchashtbl, i = 0; i < n_nchash; ncpp++, i++) 344 LIST_FOREACH(ncp, ncpp, nc_hash) 345 cntbuf[i]++; 346 CACHE_RUNLOCK(); 347 for (error = 0, i = 0; i < n_nchash; i++) 348 if ((error = SYSCTL_OUT(req, &cntbuf[i], sizeof(int))) != 0) 349 break; 350 free(cntbuf, M_TEMP); 351 return (error); 352 } 353 SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD| 354 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_rawnchash, "S,int", 355 "nchash chain lengths"); 356 357 static int 358 sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS) 359 { 360 int error; 361 struct nchashhead *ncpp; 362 struct namecache *ncp; 363 int n_nchash; 364 int count, maxlength, used, pct; 365 366 if (!req->oldptr) 367 return SYSCTL_OUT(req, 0, 4 * sizeof(int)); 368 369 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 CACHE_RLOCK(); 377 LIST_FOREACH(ncp, ncpp, nc_hash) { 378 count++; 379 } 380 CACHE_RUNLOCK(); 381 if (count) 382 used++; 383 if (maxlength < count) 384 maxlength = count; 385 } 386 n_nchash = nchash + 1; 387 pct = (used * 100) / (n_nchash / 100); 388 error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash)); 389 if (error) 390 return (error); 391 error = SYSCTL_OUT(req, &used, sizeof(used)); 392 if (error) 393 return (error); 394 error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength)); 395 if (error) 396 return (error); 397 error = SYSCTL_OUT(req, &pct, sizeof(pct)); 398 if (error) 399 return (error); 400 return (0); 401 } 402 SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD| 403 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_nchash, "I", 404 "nchash statistics (number of total/used buckets, maximum chain length, usage percentage)"); 405 #endif 406 407 /* 408 * cache_zap(): 409 * 410 * Removes a namecache entry from cache, whether it contains an actual 411 * pointer to a vnode or if it is just a negative cache entry. 412 */ 413 static void 414 cache_zap(ncp) 415 struct namecache *ncp; 416 { 417 struct vnode *vp; 418 419 rw_assert(&cache_lock, RA_WLOCKED); 420 CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp, ncp->nc_vp); 421 #ifdef KDTRACE_HOOKS 422 if (ncp->nc_vp != NULL) { 423 SDT_PROBE3(vfs, namecache, zap, done, ncp->nc_dvp, 424 nc_get_name(ncp), ncp->nc_vp); 425 } else { 426 SDT_PROBE2(vfs, namecache, zap_negative, done, ncp->nc_dvp, 427 nc_get_name(ncp)); 428 } 429 #endif 430 vp = NULL; 431 LIST_REMOVE(ncp, nc_hash); 432 if (ncp->nc_flag & NCF_ISDOTDOT) { 433 if (ncp == ncp->nc_dvp->v_cache_dd) 434 ncp->nc_dvp->v_cache_dd = NULL; 435 } else { 436 LIST_REMOVE(ncp, nc_src); 437 if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) { 438 vp = ncp->nc_dvp; 439 numcachehv--; 440 } 441 } 442 if (ncp->nc_vp) { 443 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst); 444 if (ncp == ncp->nc_vp->v_cache_dd) 445 ncp->nc_vp->v_cache_dd = NULL; 446 } else { 447 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 448 numneg--; 449 } 450 numcache--; 451 cache_free(ncp); 452 if (vp) 453 vdrop(vp); 454 } 455 456 /* 457 * Lookup an entry in the cache 458 * 459 * Lookup is called with dvp pointing to the directory to search, 460 * cnp pointing to the name of the entry being sought. If the lookup 461 * succeeds, the vnode is returned in *vpp, and a status of -1 is 462 * returned. If the lookup determines that the name does not exist 463 * (negative cacheing), a status of ENOENT is returned. If the lookup 464 * fails, a status of zero is returned. If the directory vnode is 465 * recycled out from under us due to a forced unmount, a status of 466 * ENOENT is returned. 467 * 468 * vpp is locked and ref'd on return. If we're looking up DOTDOT, dvp is 469 * unlocked. If we're looking up . an extra ref is taken, but the lock is 470 * not recursively acquired. 471 */ 472 473 int 474 cache_lookup(dvp, vpp, cnp, tsp, ticksp) 475 struct vnode *dvp; 476 struct vnode **vpp; 477 struct componentname *cnp; 478 struct timespec *tsp; 479 int *ticksp; 480 { 481 struct namecache *ncp; 482 uint32_t hash; 483 int error, ltype, wlocked; 484 485 if (!doingcache) { 486 cnp->cn_flags &= ~MAKEENTRY; 487 return (0); 488 } 489 retry: 490 CACHE_RLOCK(); 491 wlocked = 0; 492 numcalls++; 493 error = 0; 494 495 retry_wlocked: 496 if (cnp->cn_nameptr[0] == '.') { 497 if (cnp->cn_namelen == 1) { 498 *vpp = dvp; 499 CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .", 500 dvp, cnp->cn_nameptr); 501 dothits++; 502 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ".", *vpp); 503 if (tsp != NULL) 504 timespecclear(tsp); 505 if (ticksp != NULL) 506 *ticksp = ticks; 507 goto success; 508 } 509 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 510 dotdothits++; 511 if (dvp->v_cache_dd == NULL) { 512 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, 513 "..", NULL); 514 goto unlock; 515 } 516 if ((cnp->cn_flags & MAKEENTRY) == 0) { 517 if (!wlocked && !CACHE_UPGRADE_LOCK()) 518 goto wlock; 519 if (dvp->v_cache_dd->nc_flag & NCF_ISDOTDOT) 520 cache_zap(dvp->v_cache_dd); 521 dvp->v_cache_dd = NULL; 522 CACHE_WUNLOCK(); 523 return (0); 524 } 525 ncp = dvp->v_cache_dd; 526 if (ncp->nc_flag & NCF_ISDOTDOT) 527 *vpp = ncp->nc_vp; 528 else 529 *vpp = ncp->nc_dvp; 530 /* Return failure if negative entry was found. */ 531 if (*vpp == NULL) 532 goto negative_success; 533 CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..", 534 dvp, cnp->cn_nameptr, *vpp); 535 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, "..", 536 *vpp); 537 cache_out_ts(ncp, tsp, ticksp); 538 if ((ncp->nc_flag & (NCF_ISDOTDOT | NCF_DTS)) == 539 NCF_DTS && tsp != NULL) 540 *tsp = ((struct namecache_ts *)ncp)-> 541 nc_dotdottime; 542 goto success; 543 } 544 } 545 546 hash = fnv_32_buf(cnp->cn_nameptr, cnp->cn_namelen, FNV1_32_INIT); 547 hash = fnv_32_buf(&dvp, sizeof(dvp), hash); 548 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 549 numchecks++; 550 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 551 !bcmp(nc_get_name(ncp), cnp->cn_nameptr, ncp->nc_nlen)) 552 break; 553 } 554 555 /* We failed to find an entry */ 556 if (ncp == NULL) { 557 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr, 558 NULL); 559 if ((cnp->cn_flags & MAKEENTRY) == 0) { 560 nummisszap++; 561 } else { 562 nummiss++; 563 } 564 nchstats.ncs_miss++; 565 goto unlock; 566 } 567 568 /* We don't want to have an entry, so dump it */ 569 if ((cnp->cn_flags & MAKEENTRY) == 0) { 570 numposzaps++; 571 nchstats.ncs_badhits++; 572 if (!wlocked && !CACHE_UPGRADE_LOCK()) 573 goto wlock; 574 cache_zap(ncp); 575 CACHE_WUNLOCK(); 576 return (0); 577 } 578 579 /* We found a "positive" match, return the vnode */ 580 if (ncp->nc_vp) { 581 numposhits++; 582 nchstats.ncs_goodhits++; 583 *vpp = ncp->nc_vp; 584 CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p", 585 dvp, cnp->cn_nameptr, *vpp, ncp); 586 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, nc_get_name(ncp), 587 *vpp); 588 cache_out_ts(ncp, tsp, ticksp); 589 goto success; 590 } 591 592 negative_success: 593 /* We found a negative match, and want to create it, so purge */ 594 if (cnp->cn_nameiop == CREATE) { 595 numnegzaps++; 596 nchstats.ncs_badhits++; 597 if (!wlocked && !CACHE_UPGRADE_LOCK()) 598 goto wlock; 599 cache_zap(ncp); 600 CACHE_WUNLOCK(); 601 return (0); 602 } 603 604 if (!wlocked && !CACHE_UPGRADE_LOCK()) 605 goto wlock; 606 numneghits++; 607 /* 608 * We found a "negative" match, so we shift it to the end of 609 * the "negative" cache entries queue to satisfy LRU. Also, 610 * check to see if the entry is a whiteout; indicate this to 611 * the componentname, if so. 612 */ 613 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 614 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 615 nchstats.ncs_neghits++; 616 if (ncp->nc_flag & NCF_WHITE) 617 cnp->cn_flags |= ISWHITEOUT; 618 SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp, 619 nc_get_name(ncp)); 620 cache_out_ts(ncp, tsp, ticksp); 621 CACHE_WUNLOCK(); 622 return (ENOENT); 623 624 wlock: 625 /* 626 * We need to update the cache after our lookup, so upgrade to 627 * a write lock and retry the operation. 628 */ 629 CACHE_RUNLOCK(); 630 CACHE_WLOCK(); 631 numupgrades++; 632 wlocked = 1; 633 goto retry_wlocked; 634 635 success: 636 /* 637 * On success we return a locked and ref'd vnode as per the lookup 638 * protocol. 639 */ 640 if (dvp == *vpp) { /* lookup on "." */ 641 VREF(*vpp); 642 if (wlocked) 643 CACHE_WUNLOCK(); 644 else 645 CACHE_RUNLOCK(); 646 /* 647 * When we lookup "." we still can be asked to lock it 648 * differently... 649 */ 650 ltype = cnp->cn_lkflags & LK_TYPE_MASK; 651 if (ltype != VOP_ISLOCKED(*vpp)) { 652 if (ltype == LK_EXCLUSIVE) { 653 vn_lock(*vpp, LK_UPGRADE | LK_RETRY); 654 if ((*vpp)->v_iflag & VI_DOOMED) { 655 /* forced unmount */ 656 vrele(*vpp); 657 *vpp = NULL; 658 return (ENOENT); 659 } 660 } else 661 vn_lock(*vpp, LK_DOWNGRADE | LK_RETRY); 662 } 663 return (-1); 664 } 665 ltype = 0; /* silence gcc warning */ 666 if (cnp->cn_flags & ISDOTDOT) { 667 ltype = VOP_ISLOCKED(dvp); 668 VOP_UNLOCK(dvp, 0); 669 } 670 VI_LOCK(*vpp); 671 if (wlocked) 672 CACHE_WUNLOCK(); 673 else 674 CACHE_RUNLOCK(); 675 error = vget(*vpp, cnp->cn_lkflags | LK_INTERLOCK, cnp->cn_thread); 676 if (cnp->cn_flags & ISDOTDOT) { 677 vn_lock(dvp, ltype | LK_RETRY); 678 if (dvp->v_iflag & VI_DOOMED) { 679 if (error == 0) 680 vput(*vpp); 681 *vpp = NULL; 682 return (ENOENT); 683 } 684 } 685 if (error) { 686 *vpp = NULL; 687 goto retry; 688 } 689 if ((cnp->cn_flags & ISLASTCN) && 690 (cnp->cn_lkflags & LK_TYPE_MASK) == LK_EXCLUSIVE) { 691 ASSERT_VOP_ELOCKED(*vpp, "cache_lookup"); 692 } 693 return (-1); 694 695 unlock: 696 if (wlocked) 697 CACHE_WUNLOCK(); 698 else 699 CACHE_RUNLOCK(); 700 return (0); 701 } 702 703 /* 704 * Add an entry to the cache. 705 */ 706 void 707 cache_enter_time(dvp, vp, cnp, tsp, dtsp) 708 struct vnode *dvp; 709 struct vnode *vp; 710 struct componentname *cnp; 711 struct timespec *tsp; 712 struct timespec *dtsp; 713 { 714 struct namecache *ncp, *n2; 715 struct namecache_ts *n3; 716 struct nchashhead *ncpp; 717 uint32_t hash; 718 int flag; 719 int hold; 720 int zap; 721 int len; 722 723 CTR3(KTR_VFS, "cache_enter(%p, %p, %s)", dvp, vp, cnp->cn_nameptr); 724 VNASSERT(vp == NULL || (vp->v_iflag & VI_DOOMED) == 0, vp, 725 ("cache_enter: Adding a doomed vnode")); 726 VNASSERT(dvp == NULL || (dvp->v_iflag & VI_DOOMED) == 0, dvp, 727 ("cache_enter: Doomed vnode used as src")); 728 729 if (!doingcache) 730 return; 731 732 /* 733 * Avoid blowout in namecache entries. 734 */ 735 if (numcache >= desiredvnodes * ncsizefactor) 736 return; 737 738 flag = 0; 739 if (cnp->cn_nameptr[0] == '.') { 740 if (cnp->cn_namelen == 1) 741 return; 742 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 743 CACHE_WLOCK(); 744 /* 745 * If dotdot entry already exists, just retarget it 746 * to new parent vnode, otherwise continue with new 747 * namecache entry allocation. 748 */ 749 if ((ncp = dvp->v_cache_dd) != NULL && 750 ncp->nc_flag & NCF_ISDOTDOT) { 751 KASSERT(ncp->nc_dvp == dvp, 752 ("wrong isdotdot parent")); 753 if (ncp->nc_vp != NULL) { 754 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, 755 ncp, nc_dst); 756 } else { 757 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 758 numneg--; 759 } 760 if (vp != NULL) { 761 TAILQ_INSERT_HEAD(&vp->v_cache_dst, 762 ncp, nc_dst); 763 } else { 764 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 765 numneg++; 766 } 767 ncp->nc_vp = vp; 768 CACHE_WUNLOCK(); 769 return; 770 } 771 dvp->v_cache_dd = NULL; 772 SDT_PROBE3(vfs, namecache, enter, done, dvp, "..", vp); 773 CACHE_WUNLOCK(); 774 flag = NCF_ISDOTDOT; 775 } 776 } 777 778 hold = 0; 779 zap = 0; 780 781 /* 782 * Calculate the hash key and setup as much of the new 783 * namecache entry as possible before acquiring the lock. 784 */ 785 ncp = cache_alloc(cnp->cn_namelen, tsp != NULL); 786 ncp->nc_vp = vp; 787 ncp->nc_dvp = dvp; 788 ncp->nc_flag = flag; 789 if (tsp != NULL) { 790 n3 = (struct namecache_ts *)ncp; 791 n3->nc_time = *tsp; 792 n3->nc_ticks = ticks; 793 n3->nc_flag |= NCF_TS; 794 if (dtsp != NULL) { 795 n3->nc_dotdottime = *dtsp; 796 n3->nc_flag |= NCF_DTS; 797 } 798 } 799 len = ncp->nc_nlen = cnp->cn_namelen; 800 hash = fnv_32_buf(cnp->cn_nameptr, len, FNV1_32_INIT); 801 strlcpy(nc_get_name(ncp), cnp->cn_nameptr, len + 1); 802 hash = fnv_32_buf(&dvp, sizeof(dvp), hash); 803 CACHE_WLOCK(); 804 805 /* 806 * See if this vnode or negative entry is already in the cache 807 * with this name. This can happen with concurrent lookups of 808 * the same path name. 809 */ 810 ncpp = NCHHASH(hash); 811 LIST_FOREACH(n2, ncpp, nc_hash) { 812 if (n2->nc_dvp == dvp && 813 n2->nc_nlen == cnp->cn_namelen && 814 !bcmp(nc_get_name(n2), cnp->cn_nameptr, n2->nc_nlen)) { 815 if (tsp != NULL) { 816 KASSERT((n2->nc_flag & NCF_TS) != 0, 817 ("no NCF_TS")); 818 n3 = (struct namecache_ts *)n2; 819 n3->nc_time = 820 ((struct namecache_ts *)ncp)->nc_time; 821 n3->nc_ticks = 822 ((struct namecache_ts *)ncp)->nc_ticks; 823 if (dtsp != NULL) { 824 n3->nc_dotdottime = 825 ((struct namecache_ts *)ncp)-> 826 nc_dotdottime; 827 n3->nc_flag |= NCF_DTS; 828 } 829 } 830 CACHE_WUNLOCK(); 831 cache_free(ncp); 832 return; 833 } 834 } 835 836 if (flag == NCF_ISDOTDOT) { 837 /* 838 * See if we are trying to add .. entry, but some other lookup 839 * has populated v_cache_dd pointer already. 840 */ 841 if (dvp->v_cache_dd != NULL) { 842 CACHE_WUNLOCK(); 843 cache_free(ncp); 844 return; 845 } 846 KASSERT(vp == NULL || vp->v_type == VDIR, 847 ("wrong vnode type %p", vp)); 848 dvp->v_cache_dd = ncp; 849 } 850 851 numcache++; 852 if (!vp) { 853 numneg++; 854 if (cnp->cn_flags & ISWHITEOUT) 855 ncp->nc_flag |= NCF_WHITE; 856 } else if (vp->v_type == VDIR) { 857 if (flag != NCF_ISDOTDOT) { 858 /* 859 * For this case, the cache entry maps both the 860 * directory name in it and the name ".." for the 861 * directory's parent. 862 */ 863 if ((n2 = vp->v_cache_dd) != NULL && 864 (n2->nc_flag & NCF_ISDOTDOT) != 0) 865 cache_zap(n2); 866 vp->v_cache_dd = ncp; 867 } 868 } else { 869 vp->v_cache_dd = NULL; 870 } 871 872 /* 873 * Insert the new namecache entry into the appropriate chain 874 * within the cache entries table. 875 */ 876 LIST_INSERT_HEAD(ncpp, ncp, nc_hash); 877 if (flag != NCF_ISDOTDOT) { 878 if (LIST_EMPTY(&dvp->v_cache_src)) { 879 hold = 1; 880 numcachehv++; 881 } 882 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); 883 } 884 885 /* 886 * If the entry is "negative", we place it into the 887 * "negative" cache queue, otherwise, we place it into the 888 * destination vnode's cache entries queue. 889 */ 890 if (vp) { 891 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); 892 SDT_PROBE3(vfs, namecache, enter, done, dvp, nc_get_name(ncp), 893 vp); 894 } else { 895 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 896 SDT_PROBE2(vfs, namecache, enter_negative, done, dvp, 897 nc_get_name(ncp)); 898 } 899 if (numneg * ncnegfactor > numcache) { 900 ncp = TAILQ_FIRST(&ncneg); 901 KASSERT(ncp->nc_vp == NULL, ("ncp %p vp %p on ncneg", 902 ncp, ncp->nc_vp)); 903 zap = 1; 904 } 905 if (hold) 906 vhold(dvp); 907 if (zap) 908 cache_zap(ncp); 909 CACHE_WUNLOCK(); 910 } 911 912 /* 913 * Name cache initialization, from vfs_init() when we are booting 914 */ 915 static void 916 nchinit(void *dummy __unused) 917 { 918 919 TAILQ_INIT(&ncneg); 920 921 cache_zone_small = uma_zcreate("S VFS Cache", 922 sizeof(struct namecache) + CACHE_PATH_CUTOFF + 1, 923 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 924 cache_zone_small_ts = uma_zcreate("STS VFS Cache", 925 sizeof(struct namecache_ts) + CACHE_PATH_CUTOFF + 1, 926 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 927 cache_zone_large = uma_zcreate("L VFS Cache", 928 sizeof(struct namecache) + NAME_MAX + 1, 929 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 930 cache_zone_large_ts = uma_zcreate("LTS VFS Cache", 931 sizeof(struct namecache_ts) + NAME_MAX + 1, 932 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 933 934 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash); 935 } 936 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL); 937 938 void 939 cache_changesize(int newmaxvnodes) 940 { 941 struct nchashhead *new_nchashtbl, *old_nchashtbl; 942 u_long new_nchash, old_nchash; 943 struct namecache *ncp; 944 uint32_t hash; 945 int i; 946 947 new_nchashtbl = hashinit(newmaxvnodes * 2, M_VFSCACHE, &new_nchash); 948 /* If same hash table size, nothing to do */ 949 if (nchash == new_nchash) { 950 free(new_nchashtbl, M_VFSCACHE); 951 return; 952 } 953 /* 954 * Move everything from the old hash table to the new table. 955 * None of the namecache entries in the table can be removed 956 * because to do so, they have to be removed from the hash table. 957 */ 958 CACHE_WLOCK(); 959 old_nchashtbl = nchashtbl; 960 old_nchash = nchash; 961 nchashtbl = new_nchashtbl; 962 nchash = new_nchash; 963 for (i = 0; i <= old_nchash; i++) { 964 while ((ncp = LIST_FIRST(&old_nchashtbl[i])) != NULL) { 965 hash = fnv_32_buf(nc_get_name(ncp), ncp->nc_nlen, 966 FNV1_32_INIT); 967 hash = fnv_32_buf(&ncp->nc_dvp, sizeof(ncp->nc_dvp), 968 hash); 969 LIST_REMOVE(ncp, nc_hash); 970 LIST_INSERT_HEAD(NCHHASH(hash), ncp, nc_hash); 971 } 972 } 973 CACHE_WUNLOCK(); 974 free(old_nchashtbl, M_VFSCACHE); 975 } 976 977 /* 978 * Invalidate all entries to a particular vnode. 979 */ 980 void 981 cache_purge(vp) 982 struct vnode *vp; 983 { 984 985 CTR1(KTR_VFS, "cache_purge(%p)", vp); 986 SDT_PROBE1(vfs, namecache, purge, done, vp); 987 CACHE_WLOCK(); 988 while (!LIST_EMPTY(&vp->v_cache_src)) 989 cache_zap(LIST_FIRST(&vp->v_cache_src)); 990 while (!TAILQ_EMPTY(&vp->v_cache_dst)) 991 cache_zap(TAILQ_FIRST(&vp->v_cache_dst)); 992 if (vp->v_cache_dd != NULL) { 993 KASSERT(vp->v_cache_dd->nc_flag & NCF_ISDOTDOT, 994 ("lost dotdot link")); 995 cache_zap(vp->v_cache_dd); 996 } 997 KASSERT(vp->v_cache_dd == NULL, ("incomplete purge")); 998 CACHE_WUNLOCK(); 999 } 1000 1001 /* 1002 * Invalidate all negative entries for a particular directory vnode. 1003 */ 1004 void 1005 cache_purge_negative(vp) 1006 struct vnode *vp; 1007 { 1008 struct namecache *cp, *ncp; 1009 1010 CTR1(KTR_VFS, "cache_purge_negative(%p)", vp); 1011 SDT_PROBE1(vfs, namecache, purge_negative, done, vp); 1012 CACHE_WLOCK(); 1013 LIST_FOREACH_SAFE(cp, &vp->v_cache_src, nc_src, ncp) { 1014 if (cp->nc_vp == NULL) 1015 cache_zap(cp); 1016 } 1017 CACHE_WUNLOCK(); 1018 } 1019 1020 /* 1021 * Flush all entries referencing a particular filesystem. 1022 */ 1023 void 1024 cache_purgevfs(mp) 1025 struct mount *mp; 1026 { 1027 struct nchashhead *ncpp; 1028 struct namecache *ncp, *nnp; 1029 1030 /* Scan hash tables for applicable entries */ 1031 SDT_PROBE1(vfs, namecache, purgevfs, done, mp); 1032 CACHE_WLOCK(); 1033 for (ncpp = &nchashtbl[nchash]; ncpp >= nchashtbl; ncpp--) { 1034 LIST_FOREACH_SAFE(ncp, ncpp, nc_hash, nnp) { 1035 if (ncp->nc_dvp->v_mount == mp) 1036 cache_zap(ncp); 1037 } 1038 } 1039 CACHE_WUNLOCK(); 1040 } 1041 1042 /* 1043 * Perform canonical checks and cache lookup and pass on to filesystem 1044 * through the vop_cachedlookup only if needed. 1045 */ 1046 1047 int 1048 vfs_cache_lookup(ap) 1049 struct vop_lookup_args /* { 1050 struct vnode *a_dvp; 1051 struct vnode **a_vpp; 1052 struct componentname *a_cnp; 1053 } */ *ap; 1054 { 1055 struct vnode *dvp; 1056 int error; 1057 struct vnode **vpp = ap->a_vpp; 1058 struct componentname *cnp = ap->a_cnp; 1059 struct ucred *cred = cnp->cn_cred; 1060 int flags = cnp->cn_flags; 1061 struct thread *td = cnp->cn_thread; 1062 1063 *vpp = NULL; 1064 dvp = ap->a_dvp; 1065 1066 if (dvp->v_type != VDIR) 1067 return (ENOTDIR); 1068 1069 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && 1070 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 1071 return (EROFS); 1072 1073 error = VOP_ACCESS(dvp, VEXEC, cred, td); 1074 if (error) 1075 return (error); 1076 1077 error = cache_lookup(dvp, vpp, cnp, NULL, NULL); 1078 if (error == 0) 1079 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); 1080 if (error == -1) 1081 return (0); 1082 return (error); 1083 } 1084 1085 /* 1086 * XXX All of these sysctls would probably be more productive dead. 1087 */ 1088 static int disablecwd; 1089 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, 1090 "Disable the getcwd syscall"); 1091 1092 /* Implementation of the getcwd syscall. */ 1093 int 1094 sys___getcwd(td, uap) 1095 struct thread *td; 1096 struct __getcwd_args *uap; 1097 { 1098 1099 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen)); 1100 } 1101 1102 int 1103 kern___getcwd(struct thread *td, char *buf, enum uio_seg bufseg, u_int buflen) 1104 { 1105 char *bp, *tmpbuf; 1106 struct filedesc *fdp; 1107 struct vnode *cdir, *rdir; 1108 int error; 1109 1110 if (disablecwd) 1111 return (ENODEV); 1112 if (buflen < 2) 1113 return (EINVAL); 1114 if (buflen > MAXPATHLEN) 1115 buflen = MAXPATHLEN; 1116 1117 tmpbuf = malloc(buflen, M_TEMP, M_WAITOK); 1118 fdp = td->td_proc->p_fd; 1119 FILEDESC_SLOCK(fdp); 1120 cdir = fdp->fd_cdir; 1121 VREF(cdir); 1122 rdir = fdp->fd_rdir; 1123 VREF(rdir); 1124 FILEDESC_SUNLOCK(fdp); 1125 error = vn_fullpath1(td, cdir, rdir, tmpbuf, &bp, buflen); 1126 vrele(rdir); 1127 vrele(cdir); 1128 1129 if (!error) { 1130 if (bufseg == UIO_SYSSPACE) 1131 bcopy(bp, buf, strlen(bp) + 1); 1132 else 1133 error = copyout(bp, buf, strlen(bp) + 1); 1134 #ifdef KTRACE 1135 if (KTRPOINT(curthread, KTR_NAMEI)) 1136 ktrnamei(bp); 1137 #endif 1138 } 1139 free(tmpbuf, M_TEMP); 1140 return (error); 1141 } 1142 1143 /* 1144 * Thus begins the fullpath magic. 1145 */ 1146 1147 #undef STATNODE 1148 #define STATNODE(name, descr) \ 1149 static u_int name; \ 1150 SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, descr) 1151 1152 static int disablefullpath; 1153 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0, 1154 "Disable the vn_fullpath function"); 1155 1156 /* These count for kern___getcwd(), too. */ 1157 STATNODE(numfullpathcalls, "Number of fullpath search calls"); 1158 STATNODE(numfullpathfail1, "Number of fullpath search errors (ENOTDIR)"); 1159 STATNODE(numfullpathfail2, 1160 "Number of fullpath search errors (VOP_VPTOCNP failures)"); 1161 STATNODE(numfullpathfail4, "Number of fullpath search errors (ENOMEM)"); 1162 STATNODE(numfullpathfound, "Number of successful fullpath calls"); 1163 1164 /* 1165 * Retrieve the full filesystem path that correspond to a vnode from the name 1166 * cache (if available) 1167 */ 1168 int 1169 vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf) 1170 { 1171 char *buf; 1172 struct filedesc *fdp; 1173 struct vnode *rdir; 1174 int error; 1175 1176 if (disablefullpath) 1177 return (ENODEV); 1178 if (vn == NULL) 1179 return (EINVAL); 1180 1181 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 1182 fdp = td->td_proc->p_fd; 1183 FILEDESC_SLOCK(fdp); 1184 rdir = fdp->fd_rdir; 1185 VREF(rdir); 1186 FILEDESC_SUNLOCK(fdp); 1187 error = vn_fullpath1(td, vn, rdir, buf, retbuf, MAXPATHLEN); 1188 vrele(rdir); 1189 1190 if (!error) 1191 *freebuf = buf; 1192 else 1193 free(buf, M_TEMP); 1194 return (error); 1195 } 1196 1197 /* 1198 * This function is similar to vn_fullpath, but it attempts to lookup the 1199 * pathname relative to the global root mount point. This is required for the 1200 * auditing sub-system, as audited pathnames must be absolute, relative to the 1201 * global root mount point. 1202 */ 1203 int 1204 vn_fullpath_global(struct thread *td, struct vnode *vn, 1205 char **retbuf, char **freebuf) 1206 { 1207 char *buf; 1208 int error; 1209 1210 if (disablefullpath) 1211 return (ENODEV); 1212 if (vn == NULL) 1213 return (EINVAL); 1214 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 1215 error = vn_fullpath1(td, vn, rootvnode, buf, retbuf, MAXPATHLEN); 1216 if (!error) 1217 *freebuf = buf; 1218 else 1219 free(buf, M_TEMP); 1220 return (error); 1221 } 1222 1223 int 1224 vn_vptocnp(struct vnode **vp, struct ucred *cred, char *buf, u_int *buflen) 1225 { 1226 int error; 1227 1228 CACHE_RLOCK(); 1229 error = vn_vptocnp_locked(vp, cred, buf, buflen); 1230 if (error == 0) 1231 CACHE_RUNLOCK(); 1232 return (error); 1233 } 1234 1235 static int 1236 vn_vptocnp_locked(struct vnode **vp, struct ucred *cred, char *buf, 1237 u_int *buflen) 1238 { 1239 struct vnode *dvp; 1240 struct namecache *ncp; 1241 int error; 1242 1243 TAILQ_FOREACH(ncp, &((*vp)->v_cache_dst), nc_dst) { 1244 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 1245 break; 1246 } 1247 if (ncp != NULL) { 1248 if (*buflen < ncp->nc_nlen) { 1249 CACHE_RUNLOCK(); 1250 vrele(*vp); 1251 numfullpathfail4++; 1252 error = ENOMEM; 1253 SDT_PROBE3(vfs, namecache, fullpath, return, error, 1254 vp, NULL); 1255 return (error); 1256 } 1257 *buflen -= ncp->nc_nlen; 1258 memcpy(buf + *buflen, nc_get_name(ncp), ncp->nc_nlen); 1259 SDT_PROBE3(vfs, namecache, fullpath, hit, ncp->nc_dvp, 1260 nc_get_name(ncp), vp); 1261 dvp = *vp; 1262 *vp = ncp->nc_dvp; 1263 vref(*vp); 1264 CACHE_RUNLOCK(); 1265 vrele(dvp); 1266 CACHE_RLOCK(); 1267 return (0); 1268 } 1269 SDT_PROBE1(vfs, namecache, fullpath, miss, vp); 1270 1271 CACHE_RUNLOCK(); 1272 vn_lock(*vp, LK_SHARED | LK_RETRY); 1273 error = VOP_VPTOCNP(*vp, &dvp, cred, buf, buflen); 1274 vput(*vp); 1275 if (error) { 1276 numfullpathfail2++; 1277 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); 1278 return (error); 1279 } 1280 1281 *vp = dvp; 1282 CACHE_RLOCK(); 1283 if (dvp->v_iflag & VI_DOOMED) { 1284 /* forced unmount */ 1285 CACHE_RUNLOCK(); 1286 vrele(dvp); 1287 error = ENOENT; 1288 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); 1289 return (error); 1290 } 1291 /* 1292 * *vp has its use count incremented still. 1293 */ 1294 1295 return (0); 1296 } 1297 1298 /* 1299 * The magic behind kern___getcwd() and vn_fullpath(). 1300 */ 1301 static int 1302 vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 1303 char *buf, char **retbuf, u_int buflen) 1304 { 1305 int error, slash_prefixed; 1306 #ifdef KDTRACE_HOOKS 1307 struct vnode *startvp = vp; 1308 #endif 1309 struct vnode *vp1; 1310 1311 buflen--; 1312 buf[buflen] = '\0'; 1313 error = 0; 1314 slash_prefixed = 0; 1315 1316 SDT_PROBE1(vfs, namecache, fullpath, entry, vp); 1317 numfullpathcalls++; 1318 vref(vp); 1319 CACHE_RLOCK(); 1320 if (vp->v_type != VDIR) { 1321 error = vn_vptocnp_locked(&vp, td->td_ucred, buf, &buflen); 1322 if (error) 1323 return (error); 1324 if (buflen == 0) { 1325 CACHE_RUNLOCK(); 1326 vrele(vp); 1327 return (ENOMEM); 1328 } 1329 buf[--buflen] = '/'; 1330 slash_prefixed = 1; 1331 } 1332 while (vp != rdir && vp != rootvnode) { 1333 if (vp->v_vflag & VV_ROOT) { 1334 if (vp->v_iflag & VI_DOOMED) { /* forced unmount */ 1335 CACHE_RUNLOCK(); 1336 vrele(vp); 1337 error = ENOENT; 1338 SDT_PROBE3(vfs, namecache, fullpath, return, 1339 error, vp, NULL); 1340 break; 1341 } 1342 vp1 = vp->v_mount->mnt_vnodecovered; 1343 vref(vp1); 1344 CACHE_RUNLOCK(); 1345 vrele(vp); 1346 vp = vp1; 1347 CACHE_RLOCK(); 1348 continue; 1349 } 1350 if (vp->v_type != VDIR) { 1351 CACHE_RUNLOCK(); 1352 vrele(vp); 1353 numfullpathfail1++; 1354 error = ENOTDIR; 1355 SDT_PROBE3(vfs, namecache, fullpath, return, 1356 error, vp, NULL); 1357 break; 1358 } 1359 error = vn_vptocnp_locked(&vp, td->td_ucred, buf, &buflen); 1360 if (error) 1361 break; 1362 if (buflen == 0) { 1363 CACHE_RUNLOCK(); 1364 vrele(vp); 1365 error = ENOMEM; 1366 SDT_PROBE3(vfs, namecache, fullpath, return, error, 1367 startvp, NULL); 1368 break; 1369 } 1370 buf[--buflen] = '/'; 1371 slash_prefixed = 1; 1372 } 1373 if (error) 1374 return (error); 1375 if (!slash_prefixed) { 1376 if (buflen == 0) { 1377 CACHE_RUNLOCK(); 1378 vrele(vp); 1379 numfullpathfail4++; 1380 SDT_PROBE3(vfs, namecache, fullpath, return, ENOMEM, 1381 startvp, NULL); 1382 return (ENOMEM); 1383 } 1384 buf[--buflen] = '/'; 1385 } 1386 numfullpathfound++; 1387 CACHE_RUNLOCK(); 1388 vrele(vp); 1389 1390 SDT_PROBE3(vfs, namecache, fullpath, return, 0, startvp, buf + buflen); 1391 *retbuf = buf + buflen; 1392 return (0); 1393 } 1394 1395 struct vnode * 1396 vn_dir_dd_ino(struct vnode *vp) 1397 { 1398 struct namecache *ncp; 1399 struct vnode *ddvp; 1400 1401 ASSERT_VOP_LOCKED(vp, "vn_dir_dd_ino"); 1402 CACHE_RLOCK(); 1403 TAILQ_FOREACH(ncp, &(vp->v_cache_dst), nc_dst) { 1404 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) 1405 continue; 1406 ddvp = ncp->nc_dvp; 1407 VI_LOCK(ddvp); 1408 CACHE_RUNLOCK(); 1409 if (vget(ddvp, LK_INTERLOCK | LK_SHARED | LK_NOWAIT, curthread)) 1410 return (NULL); 1411 return (ddvp); 1412 } 1413 CACHE_RUNLOCK(); 1414 return (NULL); 1415 } 1416 1417 int 1418 vn_commname(struct vnode *vp, char *buf, u_int buflen) 1419 { 1420 struct namecache *ncp; 1421 int l; 1422 1423 CACHE_RLOCK(); 1424 TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst) 1425 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 1426 break; 1427 if (ncp == NULL) { 1428 CACHE_RUNLOCK(); 1429 return (ENOENT); 1430 } 1431 l = min(ncp->nc_nlen, buflen - 1); 1432 memcpy(buf, nc_get_name(ncp), l); 1433 CACHE_RUNLOCK(); 1434 buf[l] = '\0'; 1435 return (0); 1436 } 1437 1438 /* ABI compat shims for old kernel modules. */ 1439 #undef cache_enter 1440 1441 void cache_enter(struct vnode *dvp, struct vnode *vp, 1442 struct componentname *cnp); 1443 1444 void 1445 cache_enter(struct vnode *dvp, struct vnode *vp, struct componentname *cnp) 1446 { 1447 1448 cache_enter_time(dvp, vp, cnp, NULL, NULL); 1449 } 1450 1451 /* 1452 * This function updates path string to vnode's full global path 1453 * and checks the size of the new path string against the pathlen argument. 1454 * 1455 * Requires a locked, referenced vnode and GIANT lock held. 1456 * Vnode is re-locked on success or ENODEV, otherwise unlocked. 1457 * 1458 * If sysctl debug.disablefullpath is set, ENODEV is returned, 1459 * vnode is left locked and path remain untouched. 1460 * 1461 * If vp is a directory, the call to vn_fullpath_global() always succeeds 1462 * because it falls back to the ".." lookup if the namecache lookup fails. 1463 */ 1464 int 1465 vn_path_to_global_path(struct thread *td, struct vnode *vp, char *path, 1466 u_int pathlen) 1467 { 1468 struct nameidata nd; 1469 struct vnode *vp1; 1470 char *rpath, *fbuf; 1471 int error; 1472 1473 ASSERT_VOP_ELOCKED(vp, __func__); 1474 1475 /* Return ENODEV if sysctl debug.disablefullpath==1 */ 1476 if (disablefullpath) 1477 return (ENODEV); 1478 1479 /* Construct global filesystem path from vp. */ 1480 VOP_UNLOCK(vp, 0); 1481 error = vn_fullpath_global(td, vp, &rpath, &fbuf); 1482 1483 if (error != 0) { 1484 vrele(vp); 1485 return (error); 1486 } 1487 1488 if (strlen(rpath) >= pathlen) { 1489 vrele(vp); 1490 error = ENAMETOOLONG; 1491 goto out; 1492 } 1493 1494 /* 1495 * Re-lookup the vnode by path to detect a possible rename. 1496 * As a side effect, the vnode is relocked. 1497 * If vnode was renamed, return ENOENT. 1498 */ 1499 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1, 1500 UIO_SYSSPACE, path, td); 1501 error = namei(&nd); 1502 if (error != 0) { 1503 vrele(vp); 1504 goto out; 1505 } 1506 NDFREE(&nd, NDF_ONLY_PNBUF); 1507 vp1 = nd.ni_vp; 1508 vrele(vp); 1509 if (vp1 == vp) 1510 strcpy(path, rpath); 1511 else { 1512 vput(vp1); 1513 error = ENOENT; 1514 } 1515 1516 out: 1517 free(fbuf, M_TEMP); 1518 return (error); 1519 }
Cache object: 6994d809520096802064b02782c0777c
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