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