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/filedesc.h> 40 #include <sys/fnv_hash.h> 41 #include <sys/kernel.h> 42 #include <sys/lock.h> 43 #include <sys/malloc.h> 44 #include <sys/mount.h> 45 #include <sys/mutex.h> 46 #include <sys/namei.h> 47 #include <sys/proc.h> 48 #include <sys/syscallsubr.h> 49 #include <sys/sysctl.h> 50 #include <sys/sysproto.h> 51 #include <sys/systm.h> 52 #include <sys/vnode.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 CACHE_LOCK(); 203 count = 0; 204 LIST_FOREACH(ncp, ncpp, nc_hash) { 205 count++; 206 } 207 CACHE_UNLOCK(); 208 error = SYSCTL_OUT(req, &count, sizeof(count)); 209 if (error) 210 return (error); 211 } 212 return (0); 213 } 214 SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD, 215 0, 0, sysctl_debug_hashstat_rawnchash, "S,int", "nchash chain lengths"); 216 217 static int 218 sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS) 219 { 220 int error; 221 struct nchashhead *ncpp; 222 struct namecache *ncp; 223 int n_nchash; 224 int count, maxlength, used, pct; 225 226 if (!req->oldptr) 227 return SYSCTL_OUT(req, 0, 4 * sizeof(int)); 228 229 n_nchash = nchash + 1; /* nchash is max index, not count */ 230 used = 0; 231 maxlength = 0; 232 233 /* Scan hash tables for applicable entries */ 234 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { 235 count = 0; 236 CACHE_LOCK(); 237 LIST_FOREACH(ncp, ncpp, nc_hash) { 238 count++; 239 } 240 CACHE_UNLOCK(); 241 if (count) 242 used++; 243 if (maxlength < count) 244 maxlength = count; 245 } 246 n_nchash = nchash + 1; 247 pct = (used * 100 * 100) / n_nchash; 248 error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash)); 249 if (error) 250 return (error); 251 error = SYSCTL_OUT(req, &used, sizeof(used)); 252 if (error) 253 return (error); 254 error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength)); 255 if (error) 256 return (error); 257 error = SYSCTL_OUT(req, &pct, sizeof(pct)); 258 if (error) 259 return (error); 260 return (0); 261 } 262 SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD, 263 0, 0, sysctl_debug_hashstat_nchash, "I", "nchash chain lengths"); 264 265 /* 266 * cache_zap(): 267 * 268 * Removes a namecache entry from cache, whether it contains an actual 269 * pointer to a vnode or if it is just a negative cache entry. 270 */ 271 static void 272 cache_zap(ncp) 273 struct namecache *ncp; 274 { 275 struct vnode *vp; 276 277 mtx_assert(&cache_lock, MA_OWNED); 278 CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp, ncp->nc_vp); 279 vp = NULL; 280 LIST_REMOVE(ncp, nc_hash); 281 LIST_REMOVE(ncp, nc_src); 282 if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) { 283 vp = ncp->nc_dvp; 284 numcachehv--; 285 } 286 if (ncp->nc_vp) { 287 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst); 288 ncp->nc_vp->v_dd = NULL; 289 } else { 290 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 291 numneg--; 292 } 293 numcache--; 294 cache_free(ncp); 295 if (vp) 296 vdrop(vp); 297 } 298 299 /* 300 * Lookup an entry in the cache 301 * 302 * Lookup is called with dvp pointing to the directory to search, 303 * cnp pointing to the name of the entry being sought. If the lookup 304 * succeeds, the vnode is returned in *vpp, and a status of -1 is 305 * returned. If the lookup determines that the name does not exist 306 * (negative cacheing), a status of ENOENT is returned. If the lookup 307 * fails, a status of zero is returned. If the directory vnode is 308 * recycled out from under us due to a forced unmount, a status of 309 * EBADF is returned. 310 * 311 * vpp is locked and ref'd on return. If we're looking up DOTDOT, dvp is 312 * unlocked. If we're looking up . an extra ref is taken, but the lock is 313 * not recursively acquired. 314 */ 315 316 int 317 cache_lookup(dvp, vpp, cnp) 318 struct vnode *dvp; 319 struct vnode **vpp; 320 struct componentname *cnp; 321 { 322 struct namecache *ncp; 323 u_int32_t hash; 324 int error, ltype; 325 326 if (!doingcache) { 327 cnp->cn_flags &= ~MAKEENTRY; 328 return (0); 329 } 330 retry: 331 CACHE_LOCK(); 332 numcalls++; 333 334 if (cnp->cn_nameptr[0] == '.') { 335 if (cnp->cn_namelen == 1) { 336 *vpp = dvp; 337 CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .", 338 dvp, cnp->cn_nameptr); 339 dothits++; 340 goto success; 341 } 342 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 343 dotdothits++; 344 if (dvp->v_dd == NULL || 345 (cnp->cn_flags & MAKEENTRY) == 0) { 346 CACHE_UNLOCK(); 347 return (0); 348 } 349 *vpp = dvp->v_dd; 350 CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..", 351 dvp, cnp->cn_nameptr, *vpp); 352 goto success; 353 } 354 } 355 356 hash = fnv_32_buf(cnp->cn_nameptr, cnp->cn_namelen, FNV1_32_INIT); 357 hash = fnv_32_buf(&dvp, sizeof(dvp), hash); 358 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 359 numchecks++; 360 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 361 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 362 break; 363 } 364 365 /* We failed to find an entry */ 366 if (ncp == 0) { 367 if ((cnp->cn_flags & MAKEENTRY) == 0) { 368 nummisszap++; 369 } else { 370 nummiss++; 371 } 372 nchstats.ncs_miss++; 373 CACHE_UNLOCK(); 374 return (0); 375 } 376 377 /* We don't want to have an entry, so dump it */ 378 if ((cnp->cn_flags & MAKEENTRY) == 0) { 379 numposzaps++; 380 nchstats.ncs_badhits++; 381 cache_zap(ncp); 382 CACHE_UNLOCK(); 383 return (0); 384 } 385 386 /* We found a "positive" match, return the vnode */ 387 if (ncp->nc_vp) { 388 numposhits++; 389 nchstats.ncs_goodhits++; 390 *vpp = ncp->nc_vp; 391 CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p", 392 dvp, cnp->cn_nameptr, *vpp, ncp); 393 goto success; 394 } 395 396 /* We found a negative match, and want to create it, so purge */ 397 if (cnp->cn_nameiop == CREATE) { 398 numnegzaps++; 399 nchstats.ncs_badhits++; 400 cache_zap(ncp); 401 CACHE_UNLOCK(); 402 return (0); 403 } 404 405 numneghits++; 406 /* 407 * We found a "negative" match, so we shift it to the end of 408 * the "negative" cache entries queue to satisfy LRU. Also, 409 * check to see if the entry is a whiteout; indicate this to 410 * the componentname, if so. 411 */ 412 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 413 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 414 nchstats.ncs_neghits++; 415 if (ncp->nc_flag & NCF_WHITE) 416 cnp->cn_flags |= ISWHITEOUT; 417 CACHE_UNLOCK(); 418 return (ENOENT); 419 420 success: 421 /* 422 * On success we return a locked and ref'd vnode as per the lookup 423 * protocol. 424 */ 425 if (dvp == *vpp) { /* lookup on "." */ 426 VREF(*vpp); 427 CACHE_UNLOCK(); 428 /* 429 * When we lookup "." we still can be asked to lock it 430 * differently... 431 */ 432 ltype = cnp->cn_lkflags & LK_TYPE_MASK; 433 if (ltype != VOP_ISLOCKED(*vpp)) { 434 if (ltype == LK_EXCLUSIVE) { 435 vn_lock(*vpp, LK_UPGRADE | LK_RETRY); 436 if ((*vpp)->v_iflag & VI_DOOMED) { 437 /* forced unmount */ 438 vrele(*vpp); 439 *vpp = NULL; 440 return (EBADF); 441 } 442 } else 443 vn_lock(*vpp, LK_DOWNGRADE | LK_RETRY); 444 } 445 return (-1); 446 } 447 ltype = 0; /* silence gcc warning */ 448 if (cnp->cn_flags & ISDOTDOT) { 449 ltype = VOP_ISLOCKED(dvp); 450 VOP_UNLOCK(dvp, 0); 451 } 452 VI_LOCK(*vpp); 453 CACHE_UNLOCK(); 454 error = vget(*vpp, cnp->cn_lkflags | LK_INTERLOCK, cnp->cn_thread); 455 if (cnp->cn_flags & ISDOTDOT) 456 vn_lock(dvp, ltype | LK_RETRY); 457 if (error) { 458 *vpp = NULL; 459 goto retry; 460 } 461 if ((cnp->cn_flags & ISLASTCN) && 462 (cnp->cn_lkflags & LK_TYPE_MASK) == LK_EXCLUSIVE) { 463 ASSERT_VOP_ELOCKED(*vpp, "cache_lookup"); 464 } 465 return (-1); 466 } 467 468 /* 469 * Add an entry to the cache. 470 */ 471 void 472 cache_enter(dvp, vp, cnp) 473 struct vnode *dvp; 474 struct vnode *vp; 475 struct componentname *cnp; 476 { 477 struct namecache *ncp, *n2; 478 struct nchashhead *ncpp; 479 u_int32_t hash; 480 int hold; 481 int zap; 482 int len; 483 484 CTR3(KTR_VFS, "cache_enter(%p, %p, %s)", dvp, vp, cnp->cn_nameptr); 485 VNASSERT(vp == NULL || (vp->v_iflag & VI_DOOMED) == 0, vp, 486 ("cahe_enter: Adding a doomed vnode")); 487 488 if (!doingcache) 489 return; 490 491 if (cnp->cn_nameptr[0] == '.') { 492 if (cnp->cn_namelen == 1) { 493 return; 494 } 495 /* 496 * For dotdot lookups only cache the v_dd pointer if the 497 * directory has a link back to its parent via v_cache_dst. 498 * Without this an unlinked directory would keep a soft 499 * reference to its parent which could not be NULLd at 500 * cache_purge() time. 501 */ 502 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 503 CACHE_LOCK(); 504 if (!TAILQ_EMPTY(&dvp->v_cache_dst)) 505 dvp->v_dd = vp; 506 CACHE_UNLOCK(); 507 return; 508 } 509 } 510 511 hold = 0; 512 zap = 0; 513 514 /* 515 * Calculate the hash key and setup as much of the new 516 * namecache entry as possible before acquiring the lock. 517 */ 518 ncp = cache_alloc(cnp->cn_namelen); 519 ncp->nc_vp = vp; 520 ncp->nc_dvp = dvp; 521 len = ncp->nc_nlen = cnp->cn_namelen; 522 hash = fnv_32_buf(cnp->cn_nameptr, len, FNV1_32_INIT); 523 bcopy(cnp->cn_nameptr, ncp->nc_name, len); 524 hash = fnv_32_buf(&dvp, sizeof(dvp), hash); 525 CACHE_LOCK(); 526 527 /* 528 * See if this vnode is already in the cache with this name. 529 * This can happen with concurrent lookups of the same path 530 * name. 531 */ 532 if (vp) { 533 TAILQ_FOREACH(n2, &vp->v_cache_dst, nc_dst) { 534 if (n2->nc_dvp == dvp && 535 n2->nc_nlen == cnp->cn_namelen && 536 !bcmp(n2->nc_name, cnp->cn_nameptr, n2->nc_nlen)) { 537 CACHE_UNLOCK(); 538 cache_free(ncp); 539 return; 540 } 541 } 542 } else { 543 TAILQ_FOREACH(n2, &ncneg, nc_dst) { 544 if (n2->nc_nlen == cnp->cn_namelen && 545 !bcmp(n2->nc_name, cnp->cn_nameptr, n2->nc_nlen)) { 546 CACHE_UNLOCK(); 547 cache_free(ncp); 548 return; 549 } 550 } 551 } 552 553 numcache++; 554 if (!vp) { 555 numneg++; 556 ncp->nc_flag = cnp->cn_flags & ISWHITEOUT ? NCF_WHITE : 0; 557 } else if (vp->v_type == VDIR) { 558 vp->v_dd = dvp; 559 } else { 560 vp->v_dd = NULL; 561 } 562 563 /* 564 * Insert the new namecache entry into the appropriate chain 565 * within the cache entries table. 566 */ 567 ncpp = NCHHASH(hash); 568 LIST_INSERT_HEAD(ncpp, ncp, nc_hash); 569 if (LIST_EMPTY(&dvp->v_cache_src)) { 570 hold = 1; 571 numcachehv++; 572 } 573 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); 574 /* 575 * If the entry is "negative", we place it into the 576 * "negative" cache queue, otherwise, we place it into the 577 * destination vnode's cache entries queue. 578 */ 579 if (vp) { 580 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); 581 } else { 582 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 583 } 584 if (numneg * ncnegfactor > numcache) { 585 ncp = TAILQ_FIRST(&ncneg); 586 zap = 1; 587 } 588 if (hold) 589 vhold(dvp); 590 if (zap) 591 cache_zap(ncp); 592 CACHE_UNLOCK(); 593 } 594 595 /* 596 * Name cache initialization, from vfs_init() when we are booting 597 */ 598 static void 599 nchinit(void *dummy __unused) 600 { 601 602 TAILQ_INIT(&ncneg); 603 604 cache_zone_small = uma_zcreate("S VFS Cache", CACHE_ZONE_SMALL, NULL, 605 NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 606 cache_zone_large = uma_zcreate("L VFS Cache", CACHE_ZONE_LARGE, NULL, 607 NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 608 609 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash); 610 } 611 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL); 612 613 614 /* 615 * Invalidate all entries to a particular vnode. 616 */ 617 void 618 cache_purge(vp) 619 struct vnode *vp; 620 { 621 622 CTR1(KTR_VFS, "cache_purge(%p)", vp); 623 CACHE_LOCK(); 624 while (!LIST_EMPTY(&vp->v_cache_src)) 625 cache_zap(LIST_FIRST(&vp->v_cache_src)); 626 while (!TAILQ_EMPTY(&vp->v_cache_dst)) 627 cache_zap(TAILQ_FIRST(&vp->v_cache_dst)); 628 vp->v_dd = NULL; 629 CACHE_UNLOCK(); 630 } 631 632 /* 633 * Flush all entries referencing a particular filesystem. 634 */ 635 void 636 cache_purgevfs(mp) 637 struct mount *mp; 638 { 639 struct nchashhead *ncpp; 640 struct namecache *ncp, *nnp; 641 642 /* Scan hash tables for applicable entries */ 643 CACHE_LOCK(); 644 for (ncpp = &nchashtbl[nchash]; ncpp >= nchashtbl; ncpp--) { 645 LIST_FOREACH_SAFE(ncp, ncpp, nc_hash, nnp) { 646 if (ncp->nc_dvp->v_mount == mp) 647 cache_zap(ncp); 648 } 649 } 650 CACHE_UNLOCK(); 651 } 652 653 /* 654 * Perform canonical checks and cache lookup and pass on to filesystem 655 * through the vop_cachedlookup only if needed. 656 */ 657 658 int 659 vfs_cache_lookup(ap) 660 struct vop_lookup_args /* { 661 struct vnode *a_dvp; 662 struct vnode **a_vpp; 663 struct componentname *a_cnp; 664 } */ *ap; 665 { 666 struct vnode *dvp; 667 int error; 668 struct vnode **vpp = ap->a_vpp; 669 struct componentname *cnp = ap->a_cnp; 670 struct ucred *cred = cnp->cn_cred; 671 int flags = cnp->cn_flags; 672 struct thread *td = cnp->cn_thread; 673 674 *vpp = NULL; 675 dvp = ap->a_dvp; 676 677 if (dvp->v_type != VDIR) 678 return (ENOTDIR); 679 680 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && 681 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 682 return (EROFS); 683 684 error = VOP_ACCESS(dvp, VEXEC, cred, td); 685 if (error) 686 return (error); 687 688 error = cache_lookup(dvp, vpp, cnp); 689 if (error == 0) 690 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); 691 if (error == -1) 692 return (0); 693 return (error); 694 } 695 696 697 #ifndef _SYS_SYSPROTO_H_ 698 struct __getcwd_args { 699 u_char *buf; 700 u_int buflen; 701 }; 702 #endif 703 704 /* 705 * XXX All of these sysctls would probably be more productive dead. 706 */ 707 static int disablecwd; 708 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, 709 "Disable the getcwd syscall"); 710 711 /* Implementation of the getcwd syscall. */ 712 int 713 __getcwd(td, uap) 714 struct thread *td; 715 struct __getcwd_args *uap; 716 { 717 718 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen)); 719 } 720 721 int 722 kern___getcwd(struct thread *td, u_char *buf, enum uio_seg bufseg, u_int buflen) 723 { 724 char *bp, *tmpbuf; 725 struct filedesc *fdp; 726 struct vnode *cdir, *rdir; 727 int error, vfslocked; 728 729 if (disablecwd) 730 return (ENODEV); 731 if (buflen < 2) 732 return (EINVAL); 733 if (buflen > MAXPATHLEN) 734 buflen = MAXPATHLEN; 735 736 tmpbuf = malloc(buflen, M_TEMP, M_WAITOK); 737 fdp = td->td_proc->p_fd; 738 FILEDESC_SLOCK(fdp); 739 cdir = fdp->fd_cdir; 740 VREF(cdir); 741 rdir = fdp->fd_rdir; 742 VREF(rdir); 743 FILEDESC_SUNLOCK(fdp); 744 error = vn_fullpath1(td, cdir, rdir, tmpbuf, &bp, buflen); 745 vfslocked = VFS_LOCK_GIANT(rdir->v_mount); 746 vrele(rdir); 747 VFS_UNLOCK_GIANT(vfslocked); 748 vfslocked = VFS_LOCK_GIANT(cdir->v_mount); 749 vrele(cdir); 750 VFS_UNLOCK_GIANT(vfslocked); 751 752 if (!error) { 753 if (bufseg == UIO_SYSSPACE) 754 bcopy(bp, buf, strlen(bp) + 1); 755 else 756 error = copyout(bp, buf, strlen(bp) + 1); 757 } 758 free(tmpbuf, M_TEMP); 759 return (error); 760 } 761 762 /* 763 * Thus begins the fullpath magic. 764 */ 765 766 #undef STATNODE 767 #define STATNODE(name) \ 768 static u_int name; \ 769 SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, "") 770 771 static int disablefullpath; 772 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0, 773 "Disable the vn_fullpath function"); 774 775 /* These count for kern___getcwd(), too. */ 776 STATNODE(numfullpathcalls); 777 STATNODE(numfullpathfail1); 778 STATNODE(numfullpathfail2); 779 STATNODE(numfullpathfail4); 780 STATNODE(numfullpathfound); 781 782 /* 783 * Retrieve the full filesystem path that correspond to a vnode from the name 784 * cache (if available) 785 */ 786 int 787 vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf) 788 { 789 char *buf; 790 struct filedesc *fdp; 791 struct vnode *rdir; 792 int error, vfslocked; 793 794 if (disablefullpath) 795 return (ENODEV); 796 if (vn == NULL) 797 return (EINVAL); 798 799 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 800 fdp = td->td_proc->p_fd; 801 FILEDESC_SLOCK(fdp); 802 rdir = fdp->fd_rdir; 803 VREF(rdir); 804 FILEDESC_SUNLOCK(fdp); 805 error = vn_fullpath1(td, vn, rdir, buf, retbuf, MAXPATHLEN); 806 vfslocked = VFS_LOCK_GIANT(rdir->v_mount); 807 vrele(rdir); 808 VFS_UNLOCK_GIANT(vfslocked); 809 810 if (!error) 811 *freebuf = buf; 812 else 813 free(buf, M_TEMP); 814 return (error); 815 } 816 817 /* 818 * This function is similar to vn_fullpath, but it attempts to lookup the 819 * pathname relative to the global root mount point. This is required for the 820 * auditing sub-system, as audited pathnames must be absolute, relative to the 821 * global root mount point. 822 */ 823 int 824 vn_fullpath_global(struct thread *td, struct vnode *vn, 825 char **retbuf, char **freebuf) 826 { 827 char *buf; 828 int error; 829 830 if (disablefullpath) 831 return (ENODEV); 832 if (vn == NULL) 833 return (EINVAL); 834 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 835 error = vn_fullpath1(td, vn, rootvnode, buf, retbuf, MAXPATHLEN); 836 if (!error) 837 *freebuf = buf; 838 else 839 free(buf, M_TEMP); 840 return (error); 841 } 842 843 /* 844 * The magic behind kern___getcwd() and vn_fullpath(). 845 */ 846 static int 847 vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 848 char *buf, char **retbuf, u_int buflen) 849 { 850 char *bp; 851 int error, i, slash_prefixed; 852 struct namecache *ncp; 853 854 bp = buf + buflen - 1; 855 *bp = '\0'; 856 error = 0; 857 slash_prefixed = 0; 858 859 CACHE_LOCK(); 860 numfullpathcalls++; 861 if (vp->v_type != VDIR) { 862 ncp = TAILQ_FIRST(&vp->v_cache_dst); 863 if (!ncp) { 864 numfullpathfail2++; 865 CACHE_UNLOCK(); 866 return (ENOENT); 867 } 868 for (i = ncp->nc_nlen - 1; i >= 0 && bp > buf; i--) 869 *--bp = ncp->nc_name[i]; 870 if (bp == buf) { 871 numfullpathfail4++; 872 CACHE_UNLOCK(); 873 return (ENOMEM); 874 } 875 *--bp = '/'; 876 slash_prefixed = 1; 877 vp = ncp->nc_dvp; 878 } 879 while (vp != rdir && vp != rootvnode) { 880 if (vp->v_vflag & VV_ROOT) { 881 if (vp->v_iflag & VI_DOOMED) { /* forced unmount */ 882 error = EBADF; 883 break; 884 } 885 vp = vp->v_mount->mnt_vnodecovered; 886 continue; 887 } 888 if (vp->v_dd == NULL) { 889 numfullpathfail1++; 890 error = ENOTDIR; 891 break; 892 } 893 ncp = TAILQ_FIRST(&vp->v_cache_dst); 894 if (!ncp) { 895 numfullpathfail2++; 896 error = ENOENT; 897 break; 898 } 899 MPASS(ncp->nc_dvp == vp->v_dd); 900 for (i = ncp->nc_nlen - 1; i >= 0 && bp != buf; i--) 901 *--bp = ncp->nc_name[i]; 902 if (bp == buf) { 903 numfullpathfail4++; 904 error = ENOMEM; 905 break; 906 } 907 *--bp = '/'; 908 slash_prefixed = 1; 909 vp = ncp->nc_dvp; 910 } 911 if (error) { 912 CACHE_UNLOCK(); 913 return (error); 914 } 915 if (!slash_prefixed) { 916 if (bp == buf) { 917 numfullpathfail4++; 918 CACHE_UNLOCK(); 919 return (ENOMEM); 920 } else { 921 *--bp = '/'; 922 } 923 } 924 numfullpathfound++; 925 CACHE_UNLOCK(); 926 927 *retbuf = bp; 928 return (0); 929 } 930 931 int 932 vn_commname(struct vnode *vp, char *buf, u_int buflen) 933 { 934 struct namecache *ncp; 935 int l; 936 937 CACHE_LOCK(); 938 ncp = TAILQ_FIRST(&vp->v_cache_dst); 939 if (!ncp) { 940 CACHE_UNLOCK(); 941 return (ENOENT); 942 } 943 l = min(ncp->nc_nlen, buflen - 1); 944 memcpy(buf, ncp->nc_name, l); 945 CACHE_UNLOCK(); 946 buf[l] = '\0'; 947 return (0); 948 } 949