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_sizeof, OID_AUTO, namecache, CTLFLAG_RD, 0, 145 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 CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp, ncp->nc_vp); 275 vp = NULL; 276 LIST_REMOVE(ncp, nc_hash); 277 LIST_REMOVE(ncp, nc_src); 278 if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) { 279 vp = ncp->nc_dvp; 280 numcachehv--; 281 } 282 if (ncp->nc_vp) { 283 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst); 284 ncp->nc_vp->v_dd = NULL; 285 } else { 286 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 287 numneg--; 288 } 289 numcache--; 290 cache_free(ncp); 291 if (vp) 292 vdrop(vp); 293 } 294 295 /* 296 * cache_leaf_test() 297 * 298 * Test whether this (directory) vnode's namei cache entry contains 299 * subdirectories or not. Used to determine whether the directory is 300 * a leaf in the namei cache or not. Note: the directory may still 301 * contain files in the namei cache. 302 * 303 * Returns 0 if the directory is a leaf, -1 if it isn't. 304 */ 305 int 306 cache_leaf_test(struct vnode *vp) 307 { 308 struct namecache *ncpc; 309 int leaf; 310 311 leaf = 0; 312 CACHE_LOCK(); 313 for (ncpc = LIST_FIRST(&vp->v_cache_src); 314 ncpc != NULL; 315 ncpc = LIST_NEXT(ncpc, nc_src) 316 ) { 317 if (ncpc->nc_vp != NULL && ncpc->nc_vp->v_type == VDIR) { 318 leaf = -1; 319 break; 320 } 321 } 322 CACHE_UNLOCK(); 323 return (leaf); 324 } 325 326 /* 327 * Lookup an entry in the cache 328 * 329 * Lookup is called with dvp pointing to the directory to search, 330 * cnp pointing to the name of the entry being sought. If the lookup 331 * succeeds, the vnode is returned in *vpp, and a status of -1 is 332 * returned. If the lookup determines that the name does not exist 333 * (negative cacheing), a status of ENOENT is returned. If the lookup 334 * fails, a status of zero is returned. 335 * 336 * vpp is locked and ref'd on return. If we're looking up DOTDOT, dvp is 337 * unlocked. If we're looking up . an extra ref is taken, but the lock is 338 * not recursively acquired. 339 */ 340 341 int 342 cache_lookup(dvp, vpp, cnp) 343 struct vnode *dvp; 344 struct vnode **vpp; 345 struct componentname *cnp; 346 { 347 struct namecache *ncp; 348 u_int32_t hash; 349 int error; 350 351 if (!doingcache) { 352 cnp->cn_flags &= ~MAKEENTRY; 353 return (0); 354 } 355 retry: 356 CACHE_LOCK(); 357 numcalls++; 358 359 if (cnp->cn_nameptr[0] == '.') { 360 if (cnp->cn_namelen == 1) { 361 *vpp = dvp; 362 CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .", 363 dvp, cnp->cn_nameptr); 364 dothits++; 365 goto success; 366 } 367 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 368 dotdothits++; 369 if (dvp->v_dd == NULL || 370 (cnp->cn_flags & MAKEENTRY) == 0) { 371 CACHE_UNLOCK(); 372 return (0); 373 } 374 *vpp = dvp->v_dd; 375 CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..", 376 dvp, cnp->cn_nameptr, *vpp); 377 goto success; 378 } 379 } 380 381 hash = fnv_32_buf(cnp->cn_nameptr, cnp->cn_namelen, FNV1_32_INIT); 382 hash = fnv_32_buf(&dvp, sizeof(dvp), hash); 383 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 384 numchecks++; 385 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 386 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 387 break; 388 } 389 390 /* We failed to find an entry */ 391 if (ncp == 0) { 392 if ((cnp->cn_flags & MAKEENTRY) == 0) { 393 nummisszap++; 394 } else { 395 nummiss++; 396 } 397 nchstats.ncs_miss++; 398 CACHE_UNLOCK(); 399 return (0); 400 } 401 402 /* We don't want to have an entry, so dump it */ 403 if ((cnp->cn_flags & MAKEENTRY) == 0) { 404 numposzaps++; 405 nchstats.ncs_badhits++; 406 cache_zap(ncp); 407 CACHE_UNLOCK(); 408 return (0); 409 } 410 411 /* We found a "positive" match, return the vnode */ 412 if (ncp->nc_vp) { 413 numposhits++; 414 nchstats.ncs_goodhits++; 415 *vpp = ncp->nc_vp; 416 CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p", 417 dvp, cnp->cn_nameptr, *vpp, ncp); 418 goto success; 419 } 420 421 /* We found a negative match, and want to create it, so purge */ 422 if (cnp->cn_nameiop == CREATE) { 423 numnegzaps++; 424 nchstats.ncs_badhits++; 425 cache_zap(ncp); 426 CACHE_UNLOCK(); 427 return (0); 428 } 429 430 numneghits++; 431 /* 432 * We found a "negative" match, so we shift it to the end of 433 * the "negative" cache entries queue to satisfy LRU. Also, 434 * check to see if the entry is a whiteout; indicate this to 435 * the componentname, if so. 436 */ 437 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 438 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 439 nchstats.ncs_neghits++; 440 if (ncp->nc_flag & NCF_WHITE) 441 cnp->cn_flags |= ISWHITEOUT; 442 CACHE_UNLOCK(); 443 return (ENOENT); 444 445 success: 446 /* 447 * On success we return a locked and ref'd vnode as per the lookup 448 * protocol. 449 */ 450 if (dvp == *vpp) { /* lookup on "." */ 451 VREF(*vpp); 452 CACHE_UNLOCK(); 453 return (-1); 454 } 455 if (cnp->cn_flags & ISDOTDOT) 456 VOP_UNLOCK(dvp, 0, cnp->cn_thread); 457 VI_LOCK(*vpp); 458 CACHE_UNLOCK(); 459 error = vget(*vpp, cnp->cn_lkflags | LK_INTERLOCK, cnp->cn_thread); 460 if (cnp->cn_flags & ISDOTDOT) 461 vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY, cnp->cn_thread); 462 if (error) { 463 *vpp = NULL; 464 goto retry; 465 } 466 return (-1); 467 } 468 469 /* 470 * Add an entry to the cache. 471 */ 472 void 473 cache_enter(dvp, vp, cnp) 474 struct vnode *dvp; 475 struct vnode *vp; 476 struct componentname *cnp; 477 { 478 struct namecache *ncp; 479 struct nchashhead *ncpp; 480 u_int32_t hash; 481 int hold; 482 int zap; 483 int len; 484 485 CTR3(KTR_VFS, "cache_enter(%p, %p, %s)", dvp, vp, cnp->cn_nameptr); 486 VNASSERT(vp == NULL || (vp->v_iflag & VI_DOOMED) == 0, vp, 487 ("cahe_enter: Adding a doomed vnode")); 488 489 if (!doingcache) 490 return; 491 492 if (cnp->cn_nameptr[0] == '.') { 493 if (cnp->cn_namelen == 1) { 494 return; 495 } 496 /* 497 * For dotdot lookups only cache the v_dd pointer if the 498 * directory has a link back to its parent via v_cache_dst. 499 * Without this an unlinked directory would keep a soft 500 * reference to its parent which could not be NULLd at 501 * cache_purge() time. 502 */ 503 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 504 CACHE_LOCK(); 505 if (!TAILQ_EMPTY(&dvp->v_cache_dst)) 506 dvp->v_dd = vp; 507 CACHE_UNLOCK(); 508 return; 509 } 510 } 511 512 hold = 0; 513 zap = 0; 514 ncp = cache_alloc(cnp->cn_namelen); 515 CACHE_LOCK(); 516 numcache++; 517 if (!vp) { 518 numneg++; 519 ncp->nc_flag = cnp->cn_flags & ISWHITEOUT ? NCF_WHITE : 0; 520 } else if (vp->v_type == VDIR) { 521 vp->v_dd = dvp; 522 } else { 523 vp->v_dd = NULL; 524 } 525 526 /* 527 * Set the rest of the namecache entry elements, calculate it's 528 * hash key and insert it into the appropriate chain within 529 * the cache entries table. 530 */ 531 ncp->nc_vp = vp; 532 ncp->nc_dvp = dvp; 533 len = ncp->nc_nlen = cnp->cn_namelen; 534 hash = fnv_32_buf(cnp->cn_nameptr, len, FNV1_32_INIT); 535 bcopy(cnp->cn_nameptr, ncp->nc_name, len); 536 hash = fnv_32_buf(&dvp, sizeof(dvp), hash); 537 ncpp = NCHHASH(hash); 538 LIST_INSERT_HEAD(ncpp, ncp, nc_hash); 539 if (LIST_EMPTY(&dvp->v_cache_src)) { 540 hold = 1; 541 numcachehv++; 542 } 543 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); 544 /* 545 * If the entry is "negative", we place it into the 546 * "negative" cache queue, otherwise, we place it into the 547 * destination vnode's cache entries queue. 548 */ 549 if (vp) { 550 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); 551 } else { 552 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 553 } 554 if (numneg * ncnegfactor > numcache) { 555 ncp = TAILQ_FIRST(&ncneg); 556 zap = 1; 557 } 558 if (hold) 559 vhold(dvp); 560 if (zap) 561 cache_zap(ncp); 562 CACHE_UNLOCK(); 563 } 564 565 /* 566 * Name cache initialization, from vfs_init() when we are booting 567 */ 568 static void 569 nchinit(void *dummy __unused) 570 { 571 572 TAILQ_INIT(&ncneg); 573 574 cache_zone_small = uma_zcreate("S VFS Cache", CACHE_ZONE_SMALL, NULL, 575 NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 576 cache_zone_large = uma_zcreate("L VFS Cache", CACHE_ZONE_LARGE, NULL, 577 NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 578 579 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash); 580 } 581 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL) 582 583 584 /* 585 * Invalidate all entries to a particular vnode. 586 */ 587 void 588 cache_purge(vp) 589 struct vnode *vp; 590 { 591 592 CTR1(KTR_VFS, "cache_purge(%p)", vp); 593 CACHE_LOCK(); 594 while (!LIST_EMPTY(&vp->v_cache_src)) 595 cache_zap(LIST_FIRST(&vp->v_cache_src)); 596 while (!TAILQ_EMPTY(&vp->v_cache_dst)) 597 cache_zap(TAILQ_FIRST(&vp->v_cache_dst)); 598 vp->v_dd = NULL; 599 CACHE_UNLOCK(); 600 } 601 602 /* 603 * Flush all entries referencing a particular filesystem. 604 * 605 * Since we need to check it anyway, we will flush all the invalid 606 * entries at the same time. 607 */ 608 void 609 cache_purgevfs(mp) 610 struct mount *mp; 611 { 612 struct nchashhead *ncpp; 613 struct namecache *ncp, *nnp; 614 struct nchashhead mplist; 615 616 LIST_INIT(&mplist); 617 ncp = NULL; 618 619 /* Scan hash tables for applicable entries */ 620 CACHE_LOCK(); 621 for (ncpp = &nchashtbl[nchash]; ncpp >= nchashtbl; ncpp--) { 622 for (ncp = LIST_FIRST(ncpp); ncp != 0; ncp = nnp) { 623 nnp = LIST_NEXT(ncp, nc_hash); 624 if (ncp->nc_dvp->v_mount == mp) { 625 LIST_REMOVE(ncp, nc_hash); 626 LIST_INSERT_HEAD(&mplist, ncp, nc_hash); 627 } 628 } 629 } 630 while (!LIST_EMPTY(&mplist)) 631 cache_zap(LIST_FIRST(&mplist)); 632 CACHE_UNLOCK(); 633 } 634 635 /* 636 * Perform canonical checks and cache lookup and pass on to filesystem 637 * through the vop_cachedlookup only if needed. 638 */ 639 640 int 641 vfs_cache_lookup(ap) 642 struct vop_lookup_args /* { 643 struct vnode *a_dvp; 644 struct vnode **a_vpp; 645 struct componentname *a_cnp; 646 } */ *ap; 647 { 648 struct vnode *dvp; 649 int error; 650 struct vnode **vpp = ap->a_vpp; 651 struct componentname *cnp = ap->a_cnp; 652 struct ucred *cred = cnp->cn_cred; 653 int flags = cnp->cn_flags; 654 struct thread *td = cnp->cn_thread; 655 656 *vpp = NULL; 657 dvp = ap->a_dvp; 658 659 if (dvp->v_type != VDIR) 660 return (ENOTDIR); 661 662 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && 663 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 664 return (EROFS); 665 666 error = VOP_ACCESS(dvp, VEXEC, cred, td); 667 if (error) 668 return (error); 669 670 error = cache_lookup(dvp, vpp, cnp); 671 if (error == 0) 672 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); 673 if (error == ENOENT) 674 return (error); 675 return (0); 676 } 677 678 679 #ifndef _SYS_SYSPROTO_H_ 680 struct __getcwd_args { 681 u_char *buf; 682 u_int buflen; 683 }; 684 #endif 685 686 /* 687 * XXX All of these sysctls would probably be more productive dead. 688 */ 689 static int disablecwd; 690 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, 691 "Disable the getcwd syscall"); 692 693 /* Implementation of the getcwd syscall. */ 694 int 695 __getcwd(td, uap) 696 struct thread *td; 697 struct __getcwd_args *uap; 698 { 699 700 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen)); 701 } 702 703 int 704 kern___getcwd(struct thread *td, u_char *buf, enum uio_seg bufseg, u_int buflen) 705 { 706 char *bp, *tmpbuf; 707 struct filedesc *fdp; 708 int error; 709 710 if (disablecwd) 711 return (ENODEV); 712 if (buflen < 2) 713 return (EINVAL); 714 if (buflen > MAXPATHLEN) 715 buflen = MAXPATHLEN; 716 717 tmpbuf = malloc(buflen, M_TEMP, M_WAITOK); 718 fdp = td->td_proc->p_fd; 719 mtx_lock(&Giant); 720 FILEDESC_SLOCK(fdp); 721 error = vn_fullpath1(td, fdp->fd_cdir, fdp->fd_rdir, tmpbuf, 722 &bp, buflen); 723 FILEDESC_SUNLOCK(fdp); 724 mtx_unlock(&Giant); 725 726 if (!error) { 727 if (bufseg == UIO_SYSSPACE) 728 bcopy(bp, buf, strlen(bp) + 1); 729 else 730 error = copyout(bp, buf, strlen(bp) + 1); 731 } 732 free(tmpbuf, M_TEMP); 733 return (error); 734 } 735 736 /* 737 * Thus begins the fullpath magic. 738 */ 739 740 #undef STATNODE 741 #define STATNODE(name) \ 742 static u_int name; \ 743 SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, "") 744 745 static int disablefullpath; 746 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0, 747 "Disable the vn_fullpath function"); 748 749 /* These count for kern___getcwd(), too. */ 750 STATNODE(numfullpathcalls); 751 STATNODE(numfullpathfail1); 752 STATNODE(numfullpathfail2); 753 STATNODE(numfullpathfail4); 754 STATNODE(numfullpathfound); 755 756 /* 757 * Retrieve the full filesystem path that correspond to a vnode from the name 758 * cache (if available) 759 */ 760 int 761 vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf) 762 { 763 char *buf; 764 struct filedesc *fdp; 765 int error; 766 767 if (disablefullpath) 768 return (ENODEV); 769 if (vn == NULL) 770 return (EINVAL); 771 772 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 773 fdp = td->td_proc->p_fd; 774 FILEDESC_SLOCK(fdp); 775 error = vn_fullpath1(td, vn, fdp->fd_rdir, buf, retbuf, MAXPATHLEN); 776 FILEDESC_SUNLOCK(fdp); 777 778 if (!error) 779 *freebuf = buf; 780 else 781 free(buf, M_TEMP); 782 return (error); 783 } 784 785 /* 786 * The magic behind kern___getcwd() and vn_fullpath(). 787 */ 788 static int 789 vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 790 char *buf, char **retbuf, u_int buflen) 791 { 792 char *bp; 793 int error, i, slash_prefixed; 794 struct namecache *ncp; 795 796 bp = buf + buflen - 1; 797 *bp = '\0'; 798 error = 0; 799 slash_prefixed = 0; 800 801 CACHE_LOCK(); 802 numfullpathcalls++; 803 if (vp->v_type != VDIR) { 804 ncp = TAILQ_FIRST(&vp->v_cache_dst); 805 if (!ncp) { 806 numfullpathfail2++; 807 CACHE_UNLOCK(); 808 return (ENOENT); 809 } 810 for (i = ncp->nc_nlen - 1; i >= 0 && bp > buf; i--) 811 *--bp = ncp->nc_name[i]; 812 if (bp == buf) { 813 numfullpathfail4++; 814 CACHE_UNLOCK(); 815 return (ENOMEM); 816 } 817 *--bp = '/'; 818 slash_prefixed = 1; 819 vp = ncp->nc_dvp; 820 } 821 while (vp != rdir && vp != rootvnode) { 822 if (vp->v_vflag & VV_ROOT) { 823 if (vp->v_iflag & VI_DOOMED) { /* forced unmount */ 824 error = EBADF; 825 break; 826 } 827 vp = vp->v_mount->mnt_vnodecovered; 828 continue; 829 } 830 if (vp->v_dd == NULL) { 831 numfullpathfail1++; 832 error = ENOTDIR; 833 break; 834 } 835 ncp = TAILQ_FIRST(&vp->v_cache_dst); 836 if (!ncp) { 837 numfullpathfail2++; 838 error = ENOENT; 839 break; 840 } 841 MPASS(ncp->nc_dvp == vp->v_dd); 842 for (i = ncp->nc_nlen - 1; i >= 0 && bp != buf; i--) 843 *--bp = ncp->nc_name[i]; 844 if (bp == buf) { 845 numfullpathfail4++; 846 error = ENOMEM; 847 break; 848 } 849 *--bp = '/'; 850 slash_prefixed = 1; 851 vp = ncp->nc_dvp; 852 } 853 if (error) { 854 CACHE_UNLOCK(); 855 return (error); 856 } 857 if (!slash_prefixed) { 858 if (bp == buf) { 859 numfullpathfail4++; 860 CACHE_UNLOCK(); 861 return (ENOMEM); 862 } else { 863 *--bp = '/'; 864 } 865 } 866 numfullpathfound++; 867 CACHE_UNLOCK(); 868 869 *retbuf = bp; 870 return (0); 871 } 872