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 <sys/param.h> 39 #include <sys/systm.h> 40 #include <sys/kernel.h> 41 #include <sys/lock.h> 42 #include <sys/mutex.h> 43 #include <sys/sysctl.h> 44 #include <sys/mount.h> 45 #include <sys/vnode.h> 46 #include <sys/namei.h> 47 #include <sys/malloc.h> 48 #include <sys/syscallsubr.h> 49 #include <sys/sysproto.h> 50 #include <sys/proc.h> 51 #include <sys/filedesc.h> 52 #include <sys/fnv_hash.h> 53 54 #include <vm/uma.h> 55 56 /* 57 * This structure describes the elements in the cache of recent 58 * names looked up by namei. 59 */ 60 61 struct namecache { 62 LIST_ENTRY(namecache) nc_hash; /* hash chain */ 63 LIST_ENTRY(namecache) nc_src; /* source vnode list */ 64 TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */ 65 struct vnode *nc_dvp; /* vnode of parent of name */ 66 struct vnode *nc_vp; /* vnode the name refers to */ 67 u_char nc_flag; /* flag bits */ 68 u_char nc_nlen; /* length of name */ 69 char nc_name[0]; /* segment name */ 70 }; 71 72 /* 73 * Name caching works as follows: 74 * 75 * Names found by directory scans are retained in a cache 76 * for future reference. It is managed LRU, so frequently 77 * used names will hang around. Cache is indexed by hash value 78 * obtained from (vp, name) where vp refers to the directory 79 * containing name. 80 * 81 * If it is a "negative" entry, (i.e. for a name that is known NOT to 82 * exist) the vnode pointer will be NULL. 83 * 84 * Upon reaching the last segment of a path, if the reference 85 * is for DELETE, or NOCACHE is set (rewrite), and the 86 * name is located in the cache, it will be dropped. 87 */ 88 89 /* 90 * Structures associated with name cacheing. 91 */ 92 #define NCHHASH(hash) \ 93 (&nchashtbl[(hash) & nchash]) 94 static LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */ 95 static TAILQ_HEAD(, namecache) ncneg; /* Hash Table */ 96 static u_long nchash; /* size of hash table */ 97 SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, ""); 98 static u_long ncnegfactor = 16; /* ratio of negative entries */ 99 SYSCTL_ULONG(_debug, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, ""); 100 static u_long numneg; /* number of cache entries allocated */ 101 SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, ""); 102 static u_long numcache; /* number of cache entries allocated */ 103 SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, ""); 104 static u_long numcachehv; /* number of cache entries with vnodes held */ 105 SYSCTL_ULONG(_debug, OID_AUTO, numcachehv, CTLFLAG_RD, &numcachehv, 0, ""); 106 #if 0 107 static u_long numcachepl; /* number of cache purge for leaf entries */ 108 SYSCTL_ULONG(_debug, OID_AUTO, numcachepl, CTLFLAG_RD, &numcachepl, 0, ""); 109 #endif 110 struct nchstats nchstats; /* cache effectiveness statistics */ 111 112 static struct mtx cache_lock; 113 MTX_SYSINIT(vfscache, &cache_lock, "Name Cache", MTX_DEF); 114 115 #define CACHE_LOCK() mtx_lock(&cache_lock) 116 #define CACHE_UNLOCK() mtx_unlock(&cache_lock) 117 118 /* 119 * UMA zones for the VFS cache. 120 * 121 * The small cache is used for entries with short names, which are the 122 * most common. The large cache is used for entries which are too big to 123 * fit in the small cache. 124 */ 125 static uma_zone_t cache_zone_small; 126 static uma_zone_t cache_zone_large; 127 128 #define CACHE_PATH_CUTOFF 32 129 #define CACHE_ZONE_SMALL (sizeof(struct namecache) + CACHE_PATH_CUTOFF) 130 #define CACHE_ZONE_LARGE (sizeof(struct namecache) + NAME_MAX) 131 132 #define cache_alloc(len) uma_zalloc(((len) <= CACHE_PATH_CUTOFF) ? \ 133 cache_zone_small : cache_zone_large, M_WAITOK) 134 #define cache_free(ncp) do { \ 135 if (ncp != NULL) \ 136 uma_zfree(((ncp)->nc_nlen <= CACHE_PATH_CUTOFF) ? \ 137 cache_zone_small : cache_zone_large, (ncp)); \ 138 } while (0) 139 140 static int doingcache = 1; /* 1 => enable the cache */ 141 SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0, ""); 142 143 /* Export size information to userland */ 144 SYSCTL_INT(_debug, OID_AUTO, vnsize, CTLFLAG_RD, 0, sizeof(struct vnode), ""); 145 SYSCTL_INT(_debug, OID_AUTO, ncsize, CTLFLAG_RD, 0, sizeof(struct namecache), ""); 146 147 /* 148 * The new name cache statistics 149 */ 150 static SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, "Name cache statistics"); 151 #define STATNODE(mode, name, var) \ 152 SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, mode, var, 0, ""); 153 STATNODE(CTLFLAG_RD, numneg, &numneg); 154 STATNODE(CTLFLAG_RD, numcache, &numcache); 155 static u_long numcalls; STATNODE(CTLFLAG_RD, numcalls, &numcalls); 156 static u_long dothits; STATNODE(CTLFLAG_RD, dothits, &dothits); 157 static u_long dotdothits; STATNODE(CTLFLAG_RD, dotdothits, &dotdothits); 158 static u_long numchecks; STATNODE(CTLFLAG_RD, numchecks, &numchecks); 159 static u_long nummiss; STATNODE(CTLFLAG_RD, nummiss, &nummiss); 160 static u_long nummisszap; STATNODE(CTLFLAG_RD, nummisszap, &nummisszap); 161 static u_long numposzaps; STATNODE(CTLFLAG_RD, numposzaps, &numposzaps); 162 static u_long numposhits; STATNODE(CTLFLAG_RD, numposhits, &numposhits); 163 static u_long numnegzaps; STATNODE(CTLFLAG_RD, numnegzaps, &numnegzaps); 164 static u_long numneghits; STATNODE(CTLFLAG_RD, numneghits, &numneghits); 165 166 SYSCTL_OPAQUE(_vfs_cache, OID_AUTO, nchstats, CTLFLAG_RD, &nchstats, 167 sizeof(nchstats), "LU", "VFS cache effectiveness statistics"); 168 169 170 171 static void cache_zap(struct namecache *ncp); 172 static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 173 char *buf, char **retbuf, u_int buflen); 174 175 static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); 176 177 /* 178 * Flags in namecache.nc_flag 179 */ 180 #define NCF_WHITE 1 181 182 /* 183 * Grab an atomic snapshot of the name cache hash chain lengths 184 */ 185 SYSCTL_NODE(_debug, OID_AUTO, hashstat, CTLFLAG_RW, NULL, "hash table stats"); 186 187 static int 188 sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS) 189 { 190 int error; 191 struct nchashhead *ncpp; 192 struct namecache *ncp; 193 int n_nchash; 194 int count; 195 196 n_nchash = nchash + 1; /* nchash is max index, not count */ 197 if (!req->oldptr) 198 return SYSCTL_OUT(req, 0, n_nchash * sizeof(int)); 199 200 /* Scan hash tables for applicable entries */ 201 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { 202 count = 0; 203 LIST_FOREACH(ncp, ncpp, nc_hash) { 204 count++; 205 } 206 error = SYSCTL_OUT(req, &count, sizeof(count)); 207 if (error) 208 return (error); 209 } 210 return (0); 211 } 212 SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD, 213 0, 0, sysctl_debug_hashstat_rawnchash, "S,int", "nchash chain lengths"); 214 215 static int 216 sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS) 217 { 218 int error; 219 struct nchashhead *ncpp; 220 struct namecache *ncp; 221 int n_nchash; 222 int count, maxlength, used, pct; 223 224 if (!req->oldptr) 225 return SYSCTL_OUT(req, 0, 4 * sizeof(int)); 226 227 n_nchash = nchash + 1; /* nchash is max index, not count */ 228 used = 0; 229 maxlength = 0; 230 231 /* Scan hash tables for applicable entries */ 232 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { 233 count = 0; 234 LIST_FOREACH(ncp, ncpp, nc_hash) { 235 count++; 236 } 237 if (count) 238 used++; 239 if (maxlength < count) 240 maxlength = count; 241 } 242 n_nchash = nchash + 1; 243 pct = (used * 100 * 100) / n_nchash; 244 error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash)); 245 if (error) 246 return (error); 247 error = SYSCTL_OUT(req, &used, sizeof(used)); 248 if (error) 249 return (error); 250 error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength)); 251 if (error) 252 return (error); 253 error = SYSCTL_OUT(req, &pct, sizeof(pct)); 254 if (error) 255 return (error); 256 return (0); 257 } 258 SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD, 259 0, 0, sysctl_debug_hashstat_nchash, "I", "nchash chain lengths"); 260 261 /* 262 * cache_zap(): 263 * 264 * Removes a namecache entry from cache, whether it contains an actual 265 * pointer to a vnode or if it is just a negative cache entry. 266 */ 267 static void 268 cache_zap(ncp) 269 struct namecache *ncp; 270 { 271 struct vnode *vp; 272 273 mtx_assert(&cache_lock, MA_OWNED); 274 vp = NULL; 275 LIST_REMOVE(ncp, nc_hash); 276 LIST_REMOVE(ncp, nc_src); 277 if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) { 278 vp = ncp->nc_dvp; 279 numcachehv--; 280 } 281 if (ncp->nc_vp) { 282 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst); 283 } else { 284 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 285 numneg--; 286 } 287 numcache--; 288 cache_free(ncp); 289 if (vp) 290 vdrop(vp); 291 } 292 293 /* 294 * cache_leaf_test() 295 * 296 * Test whether this (directory) vnode's namei cache entry contains 297 * subdirectories or not. Used to determine whether the directory is 298 * a leaf in the namei cache or not. Note: the directory may still 299 * contain files in the namei cache. 300 * 301 * Returns 0 if the directory is a leaf, -1 if it isn't. 302 */ 303 int 304 cache_leaf_test(struct vnode *vp) 305 { 306 struct namecache *ncpc; 307 int leaf; 308 309 leaf = 0; 310 CACHE_LOCK(); 311 for (ncpc = LIST_FIRST(&vp->v_cache_src); 312 ncpc != NULL; 313 ncpc = LIST_NEXT(ncpc, nc_src) 314 ) { 315 if (ncpc->nc_vp != NULL && ncpc->nc_vp->v_type == VDIR) { 316 leaf = -1; 317 break; 318 } 319 } 320 CACHE_UNLOCK(); 321 return (leaf); 322 } 323 324 /* 325 * Lookup an entry in the cache 326 * 327 * Lookup is called with dvp pointing to the directory to search, 328 * cnp pointing to the name of the entry being sought. If the lookup 329 * succeeds, the vnode is returned in *vpp, and a status of -1 is 330 * returned. If the lookup determines that the name does not exist 331 * (negative cacheing), a status of ENOENT is returned. If the lookup 332 * fails, a status of zero is returned. 333 * 334 * vpp is locked and ref'd on return. If we're looking up DOTDOT, dvp is 335 * unlocked. If we're looking up . an extra ref is taken, but the lock is 336 * not recursively acquired. 337 */ 338 339 int 340 cache_lookup(dvp, vpp, cnp) 341 struct vnode *dvp; 342 struct vnode **vpp; 343 struct componentname *cnp; 344 { 345 struct namecache *ncp; 346 u_int32_t hash; 347 348 if (!doingcache) { 349 cnp->cn_flags &= ~MAKEENTRY; 350 return (0); 351 } 352 retry: 353 CACHE_LOCK(); 354 numcalls++; 355 356 if (cnp->cn_nameptr[0] == '.') { 357 if (cnp->cn_namelen == 1) { 358 *vpp = dvp; 359 dothits++; 360 goto success; 361 } 362 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 363 dotdothits++; 364 if (dvp->v_dd == NULL || 365 (cnp->cn_flags & MAKEENTRY) == 0) { 366 CACHE_UNLOCK(); 367 return (0); 368 } 369 *vpp = dvp->v_dd; 370 goto success; 371 } 372 } 373 374 hash = fnv_32_buf(cnp->cn_nameptr, cnp->cn_namelen, FNV1_32_INIT); 375 hash = fnv_32_buf(&dvp, sizeof(dvp), hash); 376 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 377 numchecks++; 378 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 379 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 380 break; 381 } 382 383 /* We failed to find an entry */ 384 if (ncp == 0) { 385 if ((cnp->cn_flags & MAKEENTRY) == 0) { 386 nummisszap++; 387 } else { 388 nummiss++; 389 } 390 nchstats.ncs_miss++; 391 CACHE_UNLOCK(); 392 return (0); 393 } 394 395 /* We don't want to have an entry, so dump it */ 396 if ((cnp->cn_flags & MAKEENTRY) == 0) { 397 numposzaps++; 398 nchstats.ncs_badhits++; 399 cache_zap(ncp); 400 CACHE_UNLOCK(); 401 return (0); 402 } 403 404 /* We found a "positive" match, return the vnode */ 405 if (ncp->nc_vp) { 406 numposhits++; 407 nchstats.ncs_goodhits++; 408 *vpp = ncp->nc_vp; 409 goto success; 410 } 411 412 /* We found a negative match, and want to create it, so purge */ 413 if (cnp->cn_nameiop == CREATE) { 414 numnegzaps++; 415 nchstats.ncs_badhits++; 416 cache_zap(ncp); 417 CACHE_UNLOCK(); 418 return (0); 419 } 420 421 numneghits++; 422 /* 423 * We found a "negative" match, so we shift it to the end of 424 * the "negative" cache entries queue to satisfy LRU. Also, 425 * check to see if the entry is a whiteout; indicate this to 426 * the componentname, if so. 427 */ 428 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 429 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 430 nchstats.ncs_neghits++; 431 if (ncp->nc_flag & NCF_WHITE) 432 cnp->cn_flags |= ISWHITEOUT; 433 CACHE_UNLOCK(); 434 return (ENOENT); 435 436 success: 437 /* 438 * On success we return a locked and ref'd vnode as per the lookup 439 * protocol. 440 */ 441 if (dvp == *vpp) { /* lookup on "." */ 442 VREF(*vpp); 443 CACHE_UNLOCK(); 444 return (-1); 445 } 446 if (cnp->cn_flags & ISDOTDOT) 447 VOP_UNLOCK(dvp, 0, cnp->cn_thread); 448 VI_LOCK(*vpp); 449 CACHE_UNLOCK(); 450 if (vget(*vpp, cnp->cn_lkflags | LK_INTERLOCK, cnp->cn_thread)) { 451 if (cnp->cn_flags & ISDOTDOT) 452 vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY, cnp->cn_thread); 453 *vpp = NULL; 454 goto retry; 455 } 456 return (-1); 457 } 458 459 /* 460 * Add an entry to the cache. 461 */ 462 void 463 cache_enter(dvp, vp, cnp) 464 struct vnode *dvp; 465 struct vnode *vp; 466 struct componentname *cnp; 467 { 468 struct namecache *ncp; 469 struct nchashhead *ncpp; 470 u_int32_t hash; 471 int hold; 472 int zap; 473 int len; 474 475 if (!doingcache) 476 return; 477 478 if (cnp->cn_nameptr[0] == '.') { 479 if (cnp->cn_namelen == 1) { 480 return; 481 } 482 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 483 dvp->v_dd = vp; 484 return; 485 } 486 } 487 488 hold = 0; 489 zap = 0; 490 ncp = cache_alloc(cnp->cn_namelen); 491 CACHE_LOCK(); 492 numcache++; 493 if (!vp) { 494 numneg++; 495 ncp->nc_flag = cnp->cn_flags & ISWHITEOUT ? NCF_WHITE : 0; 496 } else if (vp->v_type == VDIR) { 497 vp->v_dd = dvp; 498 } else { 499 vp->v_dd = NULL; 500 } 501 502 /* 503 * Set the rest of the namecache entry elements, calculate it's 504 * hash key and insert it into the appropriate chain within 505 * the cache entries table. 506 */ 507 ncp->nc_vp = vp; 508 ncp->nc_dvp = dvp; 509 len = ncp->nc_nlen = cnp->cn_namelen; 510 hash = fnv_32_buf(cnp->cn_nameptr, len, FNV1_32_INIT); 511 bcopy(cnp->cn_nameptr, ncp->nc_name, len); 512 hash = fnv_32_buf(&dvp, sizeof(dvp), hash); 513 ncpp = NCHHASH(hash); 514 LIST_INSERT_HEAD(ncpp, ncp, nc_hash); 515 if (LIST_EMPTY(&dvp->v_cache_src)) { 516 hold = 1; 517 numcachehv++; 518 } 519 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); 520 /* 521 * If the entry is "negative", we place it into the 522 * "negative" cache queue, otherwise, we place it into the 523 * destination vnode's cache entries queue. 524 */ 525 if (vp) { 526 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); 527 } else { 528 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 529 } 530 if (numneg * ncnegfactor > numcache) { 531 ncp = TAILQ_FIRST(&ncneg); 532 zap = 1; 533 } 534 if (hold) 535 vhold(dvp); 536 if (zap) 537 cache_zap(ncp); 538 CACHE_UNLOCK(); 539 } 540 541 /* 542 * Name cache initialization, from vfs_init() when we are booting 543 */ 544 static void 545 nchinit(void *dummy __unused) 546 { 547 548 TAILQ_INIT(&ncneg); 549 550 cache_zone_small = uma_zcreate("S VFS Cache", CACHE_ZONE_SMALL, NULL, 551 NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 552 cache_zone_large = uma_zcreate("L VFS Cache", CACHE_ZONE_LARGE, NULL, 553 NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 554 555 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash); 556 } 557 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL) 558 559 560 /* 561 * Invalidate all entries to a particular vnode. 562 */ 563 void 564 cache_purge(vp) 565 struct vnode *vp; 566 { 567 struct namecache *ncp; 568 569 CACHE_LOCK(); 570 while (!LIST_EMPTY(&vp->v_cache_src)) { 571 struct vnode *cvp; 572 573 ncp = LIST_FIRST(&vp->v_cache_src); 574 /* 575 * We must reset v_dd of any children so they don't 576 * continue to point to us. 577 */ 578 if ((cvp = ncp->nc_vp) && cvp->v_dd == vp) 579 cvp->v_dd = NULL; 580 cache_zap(ncp); 581 } 582 while (!TAILQ_EMPTY(&vp->v_cache_dst)) 583 cache_zap(TAILQ_FIRST(&vp->v_cache_dst)); 584 vp->v_dd = NULL; 585 CACHE_UNLOCK(); 586 } 587 588 /* 589 * Flush all entries referencing a particular filesystem. 590 * 591 * Since we need to check it anyway, we will flush all the invalid 592 * entries at the same time. 593 */ 594 void 595 cache_purgevfs(mp) 596 struct mount *mp; 597 { 598 struct nchashhead *ncpp; 599 struct namecache *ncp, *nnp; 600 struct nchashhead mplist; 601 602 LIST_INIT(&mplist); 603 ncp = NULL; 604 605 /* Scan hash tables for applicable entries */ 606 CACHE_LOCK(); 607 for (ncpp = &nchashtbl[nchash]; ncpp >= nchashtbl; ncpp--) { 608 for (ncp = LIST_FIRST(ncpp); ncp != 0; ncp = nnp) { 609 nnp = LIST_NEXT(ncp, nc_hash); 610 if (ncp->nc_dvp->v_mount == mp) { 611 LIST_REMOVE(ncp, nc_hash); 612 LIST_INSERT_HEAD(&mplist, ncp, nc_hash); 613 } 614 } 615 } 616 while (!LIST_EMPTY(&mplist)) 617 cache_zap(LIST_FIRST(&mplist)); 618 CACHE_UNLOCK(); 619 } 620 621 /* 622 * Perform canonical checks and cache lookup and pass on to filesystem 623 * through the vop_cachedlookup only if needed. 624 */ 625 626 int 627 vfs_cache_lookup(ap) 628 struct vop_lookup_args /* { 629 struct vnode *a_dvp; 630 struct vnode **a_vpp; 631 struct componentname *a_cnp; 632 } */ *ap; 633 { 634 struct vnode *dvp; 635 int error; 636 struct vnode **vpp = ap->a_vpp; 637 struct componentname *cnp = ap->a_cnp; 638 struct ucred *cred = cnp->cn_cred; 639 int flags = cnp->cn_flags; 640 struct thread *td = cnp->cn_thread; 641 642 *vpp = NULL; 643 dvp = ap->a_dvp; 644 645 if (dvp->v_type != VDIR) 646 return (ENOTDIR); 647 648 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && 649 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 650 return (EROFS); 651 652 error = VOP_ACCESS(dvp, VEXEC, cred, td); 653 if (error) 654 return (error); 655 656 error = cache_lookup(dvp, vpp, cnp); 657 if (error == 0) 658 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); 659 if (error == ENOENT) 660 return (error); 661 return (0); 662 } 663 664 665 #ifndef _SYS_SYSPROTO_H_ 666 struct __getcwd_args { 667 u_char *buf; 668 u_int buflen; 669 }; 670 #endif 671 672 /* 673 * XXX All of these sysctls would probably be more productive dead. 674 */ 675 static int disablecwd; 676 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, 677 "Disable the getcwd syscall"); 678 679 /* Implementation of the getcwd syscall */ 680 int 681 __getcwd(td, uap) 682 struct thread *td; 683 struct __getcwd_args *uap; 684 { 685 686 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen)); 687 } 688 689 int 690 kern___getcwd(struct thread *td, u_char *buf, enum uio_seg bufseg, u_int buflen) 691 { 692 char *bp, *tmpbuf; 693 struct filedesc *fdp; 694 int error; 695 696 if (disablecwd) 697 return (ENODEV); 698 if (buflen < 2) 699 return (EINVAL); 700 if (buflen > MAXPATHLEN) 701 buflen = MAXPATHLEN; 702 703 tmpbuf = malloc(buflen, M_TEMP, M_WAITOK); 704 fdp = td->td_proc->p_fd; 705 mtx_lock(&Giant); 706 FILEDESC_LOCK(fdp); 707 error = vn_fullpath1(td, fdp->fd_cdir, fdp->fd_rdir, tmpbuf, 708 &bp, buflen); 709 FILEDESC_UNLOCK(fdp); 710 mtx_unlock(&Giant); 711 712 if (!error) { 713 if (bufseg == UIO_SYSSPACE) 714 bcopy(bp, buf, strlen(bp) + 1); 715 else 716 error = copyout(bp, buf, strlen(bp) + 1); 717 } 718 free(tmpbuf, M_TEMP); 719 return (error); 720 } 721 722 /* 723 * Thus begins the fullpath magic. 724 */ 725 726 #undef STATNODE 727 #define STATNODE(name) \ 728 static u_int name; \ 729 SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, "") 730 731 static int disablefullpath; 732 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0, 733 "Disable the vn_fullpath function"); 734 735 /* These count for kern___getcwd(), too. */ 736 STATNODE(numfullpathcalls); 737 STATNODE(numfullpathfail1); 738 STATNODE(numfullpathfail2); 739 STATNODE(numfullpathfail4); 740 STATNODE(numfullpathfound); 741 742 /* 743 * Retrieve the full filesystem path that correspond to a vnode from the name 744 * cache (if available) 745 */ 746 int 747 vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf) 748 { 749 char *buf; 750 struct filedesc *fdp; 751 int error; 752 753 if (disablefullpath) 754 return (ENODEV); 755 if (vn == NULL) 756 return (EINVAL); 757 758 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 759 fdp = td->td_proc->p_fd; 760 mtx_lock(&Giant); 761 FILEDESC_LOCK(fdp); 762 error = vn_fullpath1(td, vn, fdp->fd_rdir, buf, retbuf, MAXPATHLEN); 763 FILEDESC_UNLOCK(fdp); 764 mtx_unlock(&Giant); 765 766 if (!error) 767 *freebuf = buf; 768 else 769 free(buf, M_TEMP); 770 return (error); 771 } 772 773 /* 774 * The magic behind kern___getcwd() and vn_fullpath(). 775 */ 776 static int 777 vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 778 char *buf, char **retbuf, u_int buflen) 779 { 780 char *bp; 781 int error, i, slash_prefixed; 782 struct namecache *ncp; 783 784 mtx_assert(&Giant, MA_OWNED); 785 786 bp = buf + buflen - 1; 787 *bp = '\0'; 788 error = 0; 789 slash_prefixed = 0; 790 791 CACHE_LOCK(); 792 numfullpathcalls++; 793 if (vp->v_type != VDIR) { 794 ncp = TAILQ_FIRST(&vp->v_cache_dst); 795 if (!ncp) { 796 numfullpathfail2++; 797 CACHE_UNLOCK(); 798 return (ENOENT); 799 } 800 for (i = ncp->nc_nlen - 1; i >= 0 && bp > buf; i--) 801 *--bp = ncp->nc_name[i]; 802 if (bp == buf) { 803 numfullpathfail4++; 804 CACHE_UNLOCK(); 805 return (ENOMEM); 806 } 807 *--bp = '/'; 808 slash_prefixed = 1; 809 vp = ncp->nc_dvp; 810 } 811 while (vp != rdir && vp != rootvnode) { 812 if (vp->v_vflag & VV_ROOT) { 813 if (vp->v_mount == NULL) { /* forced unmount */ 814 error = EBADF; 815 break; 816 } 817 vp = vp->v_mount->mnt_vnodecovered; 818 continue; 819 } 820 if (vp->v_dd == NULL) { 821 numfullpathfail1++; 822 error = ENOTDIR; 823 break; 824 } 825 ncp = TAILQ_FIRST(&vp->v_cache_dst); 826 if (!ncp) { 827 numfullpathfail2++; 828 error = ENOENT; 829 break; 830 } 831 MPASS(ncp->nc_dvp == vp->v_dd); 832 for (i = ncp->nc_nlen - 1; i >= 0 && bp != buf; i--) 833 *--bp = ncp->nc_name[i]; 834 if (bp == buf) { 835 numfullpathfail4++; 836 error = ENOMEM; 837 break; 838 } 839 *--bp = '/'; 840 slash_prefixed = 1; 841 vp = ncp->nc_dvp; 842 } 843 if (error) { 844 CACHE_UNLOCK(); 845 return (error); 846 } 847 if (!slash_prefixed) { 848 if (bp == buf) { 849 numfullpathfail4++; 850 CACHE_UNLOCK(); 851 return (ENOMEM); 852 } else { 853 *--bp = '/'; 854 } 855 } 856 numfullpathfound++; 857 CACHE_UNLOCK(); 858 859 *retbuf = bp; 860 return (0); 861 } 862