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 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * @(#)vfs_cache.c 8.5 (Berkeley) 3/22/95 37 */ 38 39 #include <sys/cdefs.h> 40 __FBSDID("$FreeBSD$"); 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/kernel.h> 45 #include <sys/lock.h> 46 #include <sys/mutex.h> 47 #include <sys/sysctl.h> 48 #include <sys/mount.h> 49 #include <sys/vnode.h> 50 #include <sys/namei.h> 51 #include <sys/malloc.h> 52 #include <sys/syscallsubr.h> 53 #include <sys/sysproto.h> 54 #include <sys/proc.h> 55 #include <sys/filedesc.h> 56 #include <sys/fnv_hash.h> 57 58 #include <vm/uma.h> 59 60 /* 61 * This structure describes the elements in the cache of recent 62 * names looked up by namei. 63 */ 64 65 struct namecache { 66 LIST_ENTRY(namecache) nc_hash; /* hash chain */ 67 LIST_ENTRY(namecache) nc_src; /* source vnode list */ 68 TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */ 69 struct vnode *nc_dvp; /* vnode of parent of name */ 70 struct vnode *nc_vp; /* vnode the name refers to */ 71 u_char nc_flag; /* flag bits */ 72 u_char nc_nlen; /* length of name */ 73 char nc_name[0]; /* segment name */ 74 }; 75 76 /* 77 * Name caching works as follows: 78 * 79 * Names found by directory scans are retained in a cache 80 * for future reference. It is managed LRU, so frequently 81 * used names will hang around. Cache is indexed by hash value 82 * obtained from (vp, name) where vp refers to the directory 83 * containing name. 84 * 85 * If it is a "negative" entry, (i.e. for a name that is known NOT to 86 * exist) the vnode pointer will be NULL. 87 * 88 * Upon reaching the last segment of a path, if the reference 89 * is for DELETE, or NOCACHE is set (rewrite), and the 90 * name is located in the cache, it will be dropped. 91 */ 92 93 /* 94 * Structures associated with name cacheing. 95 */ 96 #define NCHHASH(hash) \ 97 (&nchashtbl[(hash) & nchash]) 98 static LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */ 99 static TAILQ_HEAD(, namecache) ncneg; /* Hash Table */ 100 static u_long nchash; /* size of hash table */ 101 SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, ""); 102 static u_long ncnegfactor = 16; /* ratio of negative entries */ 103 SYSCTL_ULONG(_debug, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, ""); 104 static u_long numneg; /* number of cache entries allocated */ 105 SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, ""); 106 static u_long numcache; /* number of cache entries allocated */ 107 SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, ""); 108 static u_long numcachehv; /* number of cache entries with vnodes held */ 109 SYSCTL_ULONG(_debug, OID_AUTO, numcachehv, CTLFLAG_RD, &numcachehv, 0, ""); 110 #if 0 111 static u_long numcachepl; /* number of cache purge for leaf entries */ 112 SYSCTL_ULONG(_debug, OID_AUTO, numcachepl, CTLFLAG_RD, &numcachepl, 0, ""); 113 #endif 114 struct nchstats nchstats; /* cache effectiveness statistics */ 115 116 /* 117 * UMA zones for the VFS cache. 118 * 119 * The small cache is used for entries with short names, which are the 120 * most common. The large cache is used for entries which are too big to 121 * fit in the small cache. 122 */ 123 static uma_zone_t cache_zone_small; 124 static uma_zone_t cache_zone_large; 125 126 #define CACHE_PATH_CUTOFF 32 127 #define CACHE_ZONE_SMALL (sizeof(struct namecache) + CACHE_PATH_CUTOFF) 128 #define CACHE_ZONE_LARGE (sizeof(struct namecache) + NAME_MAX) 129 130 #define cache_alloc(len) uma_zalloc(((len) <= CACHE_PATH_CUTOFF) ? \ 131 cache_zone_small : cache_zone_large, M_WAITOK) 132 #define cache_free(ncp) do { \ 133 if (ncp != NULL) \ 134 uma_zfree(((ncp)->nc_nlen <= CACHE_PATH_CUTOFF) ? \ 135 cache_zone_small : cache_zone_large, (ncp)); \ 136 } while (0) 137 138 static int doingcache = 1; /* 1 => enable the cache */ 139 SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0, ""); 140 141 /* Export size information to userland */ 142 SYSCTL_INT(_debug, OID_AUTO, vnsize, CTLFLAG_RD, 0, sizeof(struct vnode), ""); 143 SYSCTL_INT(_debug, OID_AUTO, ncsize, CTLFLAG_RD, 0, sizeof(struct namecache), ""); 144 145 /* 146 * The new name cache statistics 147 */ 148 SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, "Name cache statistics"); 149 #define STATNODE(mode, name, var) \ 150 SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, mode, var, 0, ""); 151 STATNODE(CTLFLAG_RD, numneg, &numneg); 152 STATNODE(CTLFLAG_RD, numcache, &numcache); 153 static u_long numcalls; STATNODE(CTLFLAG_RD, numcalls, &numcalls); 154 static u_long dothits; STATNODE(CTLFLAG_RD, dothits, &dothits); 155 static u_long dotdothits; STATNODE(CTLFLAG_RD, dotdothits, &dotdothits); 156 static u_long numchecks; STATNODE(CTLFLAG_RD, numchecks, &numchecks); 157 static u_long nummiss; STATNODE(CTLFLAG_RD, nummiss, &nummiss); 158 static u_long nummisszap; STATNODE(CTLFLAG_RD, nummisszap, &nummisszap); 159 static u_long numposzaps; STATNODE(CTLFLAG_RD, numposzaps, &numposzaps); 160 static u_long numposhits; STATNODE(CTLFLAG_RD, numposhits, &numposhits); 161 static u_long numnegzaps; STATNODE(CTLFLAG_RD, numnegzaps, &numnegzaps); 162 static u_long numneghits; STATNODE(CTLFLAG_RD, numneghits, &numneghits); 163 164 SYSCTL_OPAQUE(_vfs_cache, OID_AUTO, nchstats, CTLFLAG_RD, &nchstats, 165 sizeof(nchstats), "LU", "VFS cache effectiveness statistics"); 166 167 168 169 static void cache_zap(struct namecache *ncp); 170 171 static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); 172 173 /* 174 * Flags in namecache.nc_flag 175 */ 176 #define NCF_WHITE 1 177 178 /* 179 * Grab an atomic snapshot of the name cache hash chain lengths 180 */ 181 SYSCTL_NODE(_debug, OID_AUTO, hashstat, CTLFLAG_RW, NULL, "hash table stats"); 182 183 static int 184 sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS) 185 { 186 int error; 187 struct nchashhead *ncpp; 188 struct namecache *ncp; 189 int n_nchash; 190 int count; 191 192 n_nchash = nchash + 1; /* nchash is max index, not count */ 193 if (!req->oldptr) 194 return SYSCTL_OUT(req, 0, n_nchash * sizeof(int)); 195 196 /* Scan hash tables for applicable entries */ 197 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { 198 count = 0; 199 LIST_FOREACH(ncp, ncpp, nc_hash) { 200 count++; 201 } 202 error = SYSCTL_OUT(req, &count, sizeof(count)); 203 if (error) 204 return (error); 205 } 206 return (0); 207 } 208 SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD, 209 0, 0, sysctl_debug_hashstat_rawnchash, "S,int", "nchash chain lengths"); 210 211 static int 212 sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS) 213 { 214 int error; 215 struct nchashhead *ncpp; 216 struct namecache *ncp; 217 int n_nchash; 218 int count, maxlength, used, pct; 219 220 if (!req->oldptr) 221 return SYSCTL_OUT(req, 0, 4 * sizeof(int)); 222 223 n_nchash = nchash + 1; /* nchash is max index, not count */ 224 used = 0; 225 maxlength = 0; 226 227 /* Scan hash tables for applicable entries */ 228 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { 229 count = 0; 230 LIST_FOREACH(ncp, ncpp, nc_hash) { 231 count++; 232 } 233 if (count) 234 used++; 235 if (maxlength < count) 236 maxlength = count; 237 } 238 n_nchash = nchash + 1; 239 pct = (used * 100 * 100) / n_nchash; 240 error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash)); 241 if (error) 242 return (error); 243 error = SYSCTL_OUT(req, &used, sizeof(used)); 244 if (error) 245 return (error); 246 error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength)); 247 if (error) 248 return (error); 249 error = SYSCTL_OUT(req, &pct, sizeof(pct)); 250 if (error) 251 return (error); 252 return (0); 253 } 254 SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD, 255 0, 0, sysctl_debug_hashstat_nchash, "I", "nchash chain lengths"); 256 257 /* 258 * cache_zap(): 259 * 260 * Removes a namecache entry from cache, whether it contains an actual 261 * pointer to a vnode or if it is just a negative cache entry. 262 */ 263 static void 264 cache_zap(ncp) 265 struct namecache *ncp; 266 { 267 LIST_REMOVE(ncp, nc_hash); 268 LIST_REMOVE(ncp, nc_src); 269 if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) { 270 vdrop(ncp->nc_dvp); 271 numcachehv--; 272 } 273 if (ncp->nc_vp) { 274 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst); 275 } else { 276 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 277 numneg--; 278 } 279 numcache--; 280 cache_free(ncp); 281 } 282 283 /* 284 * cache_leaf_test() 285 * 286 * Test whether this (directory) vnode's namei cache entry contains 287 * subdirectories or not. Used to determine whether the directory is 288 * a leaf in the namei cache or not. Note: the directory may still 289 * contain files in the namei cache. 290 * 291 * Returns 0 if the directory is a leaf, -1 if it isn't. 292 */ 293 int 294 cache_leaf_test(struct vnode *vp) 295 { 296 struct namecache *ncpc; 297 298 for (ncpc = LIST_FIRST(&vp->v_cache_src); 299 ncpc != NULL; 300 ncpc = LIST_NEXT(ncpc, nc_src) 301 ) { 302 if (ncpc->nc_vp != NULL && ncpc->nc_vp->v_type == VDIR) 303 return(-1); 304 } 305 return(0); 306 } 307 308 /* 309 * Lookup an entry in the cache 310 * 311 * Lookup is called with dvp pointing to the directory to search, 312 * cnp pointing to the name of the entry being sought. If the lookup 313 * succeeds, the vnode is returned in *vpp, and a status of -1 is 314 * returned. If the lookup determines that the name does not exist 315 * (negative cacheing), a status of ENOENT is returned. If the lookup 316 * fails, a status of zero is returned. 317 */ 318 319 int 320 cache_lookup(dvp, vpp, cnp) 321 struct vnode *dvp; 322 struct vnode **vpp; 323 struct componentname *cnp; 324 { 325 struct namecache *ncp; 326 u_int32_t hash; 327 328 if (!doingcache) { 329 cnp->cn_flags &= ~MAKEENTRY; 330 return (0); 331 } 332 333 numcalls++; 334 335 if (cnp->cn_nameptr[0] == '.') { 336 if (cnp->cn_namelen == 1) { 337 *vpp = dvp; 338 dothits++; 339 return (-1); 340 } 341 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 342 dotdothits++; 343 if (dvp->v_dd->v_id != dvp->v_ddid || 344 (cnp->cn_flags & MAKEENTRY) == 0) { 345 dvp->v_ddid = 0; 346 return (0); 347 } 348 *vpp = dvp->v_dd; 349 return (-1); 350 } 351 } 352 353 hash = fnv_32_buf(cnp->cn_nameptr, cnp->cn_namelen, FNV1_32_INIT); 354 hash = fnv_32_buf(&dvp->v_id, sizeof(dvp->v_id), hash); 355 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 356 numchecks++; 357 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 358 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 359 break; 360 } 361 362 /* We failed to find an entry */ 363 if (ncp == 0) { 364 if ((cnp->cn_flags & MAKEENTRY) == 0) { 365 nummisszap++; 366 } else { 367 nummiss++; 368 } 369 nchstats.ncs_miss++; 370 return (0); 371 } 372 373 /* We don't want to have an entry, so dump it */ 374 if ((cnp->cn_flags & MAKEENTRY) == 0) { 375 numposzaps++; 376 nchstats.ncs_badhits++; 377 cache_zap(ncp); 378 return (0); 379 } 380 381 /* We found a "positive" match, return the vnode */ 382 if (ncp->nc_vp) { 383 numposhits++; 384 nchstats.ncs_goodhits++; 385 *vpp = ncp->nc_vp; 386 return (-1); 387 } 388 389 /* We found a negative match, and want to create it, so purge */ 390 if (cnp->cn_nameiop == CREATE) { 391 numnegzaps++; 392 nchstats.ncs_badhits++; 393 cache_zap(ncp); 394 return (0); 395 } 396 397 numneghits++; 398 /* 399 * We found a "negative" match, so we shift it to the end of 400 * the "negative" cache entries queue to satisfy LRU. Also, 401 * check to see if the entry is a whiteout; indicate this to 402 * the componentname, if so. 403 */ 404 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 405 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 406 nchstats.ncs_neghits++; 407 if (ncp->nc_flag & NCF_WHITE) 408 cnp->cn_flags |= ISWHITEOUT; 409 return (ENOENT); 410 } 411 412 /* 413 * Add an entry to the cache. 414 */ 415 void 416 cache_enter(dvp, vp, cnp) 417 struct vnode *dvp; 418 struct vnode *vp; 419 struct componentname *cnp; 420 { 421 struct namecache *ncp; 422 struct nchashhead *ncpp; 423 u_int32_t hash; 424 int len; 425 426 if (!doingcache) 427 return; 428 429 if (cnp->cn_nameptr[0] == '.') { 430 if (cnp->cn_namelen == 1) { 431 return; 432 } 433 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 434 if (vp) { 435 dvp->v_dd = vp; 436 dvp->v_ddid = vp->v_id; 437 } else { 438 dvp->v_dd = dvp; 439 dvp->v_ddid = 0; 440 } 441 return; 442 } 443 } 444 445 ncp = cache_alloc(cnp->cn_namelen); 446 /* XXX can uma_zalloc(..., M_WAITOK) fail? */ 447 numcache++; 448 if (!vp) { 449 numneg++; 450 ncp->nc_flag = cnp->cn_flags & ISWHITEOUT ? NCF_WHITE : 0; 451 } else if (vp->v_type == VDIR) { 452 vp->v_dd = dvp; 453 vp->v_ddid = dvp->v_id; 454 } 455 456 /* 457 * Set the rest of the namecache entry elements, calculate it's 458 * hash key and insert it into the appropriate chain within 459 * the cache entries table. 460 */ 461 ncp->nc_vp = vp; 462 ncp->nc_dvp = dvp; 463 len = ncp->nc_nlen = cnp->cn_namelen; 464 hash = fnv_32_buf(cnp->cn_nameptr, len, FNV1_32_INIT); 465 bcopy(cnp->cn_nameptr, ncp->nc_name, len); 466 hash = fnv_32_buf(&dvp->v_id, sizeof(dvp->v_id), hash); 467 ncpp = NCHHASH(hash); 468 LIST_INSERT_HEAD(ncpp, ncp, nc_hash); 469 if (LIST_EMPTY(&dvp->v_cache_src)) { 470 vhold(dvp); 471 numcachehv++; 472 } 473 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); 474 /* 475 * If the entry is "negative", we place it into the 476 * "negative" cache queue, otherwise, we place it into the 477 * destination vnode's cache entries queue. 478 */ 479 if (vp) { 480 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); 481 } else { 482 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 483 } 484 if (numneg * ncnegfactor > numcache) { 485 ncp = TAILQ_FIRST(&ncneg); 486 cache_zap(ncp); 487 } 488 } 489 490 /* 491 * Name cache initialization, from vfs_init() when we are booting 492 */ 493 static void 494 nchinit(void *dummy __unused) 495 { 496 497 TAILQ_INIT(&ncneg); 498 499 cache_zone_small = uma_zcreate("S VFS Cache", CACHE_ZONE_SMALL, NULL, 500 NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 501 cache_zone_large = uma_zcreate("L VFS Cache", CACHE_ZONE_LARGE, NULL, 502 NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 503 504 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash); 505 } 506 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL) 507 508 509 /* 510 * Invalidate all entries to a particular vnode. 511 * 512 * Remove all entries in the namecache relating to this vnode and 513 * change the v_id. We take the v_id from a global counter, since 514 * it becomes a handy sequence number in crash-dumps that way. 515 * No valid vnode will ever have (v_id == 0). 516 * 517 * XXX: Only time and the size of v_id prevents this from failing: 518 * XXX: In theory we should hunt down all (struct vnode*, v_id) 519 * XXX: soft references and nuke them, at least on the global 520 * XXX: v_id wraparound. The period of resistance can be extended 521 * XXX: by incrementing each vnodes v_id individually instead of 522 * XXX: using the global v_id. 523 */ 524 525 void 526 cache_purge(vp) 527 struct vnode *vp; 528 { 529 static u_long nextid; 530 531 while (!LIST_EMPTY(&vp->v_cache_src)) 532 cache_zap(LIST_FIRST(&vp->v_cache_src)); 533 while (!TAILQ_EMPTY(&vp->v_cache_dst)) 534 cache_zap(TAILQ_FIRST(&vp->v_cache_dst)); 535 536 do 537 nextid++; 538 while (nextid == vp->v_id || !nextid); 539 vp->v_id = nextid; 540 vp->v_dd = vp; 541 vp->v_ddid = 0; 542 } 543 544 /* 545 * Flush all entries referencing a particular filesystem. 546 * 547 * Since we need to check it anyway, we will flush all the invalid 548 * entries at the same time. 549 */ 550 void 551 cache_purgevfs(mp) 552 struct mount *mp; 553 { 554 struct nchashhead *ncpp; 555 struct namecache *ncp, *nnp; 556 557 /* Scan hash tables for applicable entries */ 558 for (ncpp = &nchashtbl[nchash]; ncpp >= nchashtbl; ncpp--) { 559 for (ncp = LIST_FIRST(ncpp); ncp != 0; ncp = nnp) { 560 nnp = LIST_NEXT(ncp, nc_hash); 561 if (ncp->nc_dvp->v_mount == mp) { 562 cache_zap(ncp); 563 } 564 } 565 } 566 } 567 568 /* 569 * Perform canonical checks and cache lookup and pass on to filesystem 570 * through the vop_cachedlookup only if needed. 571 */ 572 573 int 574 vfs_cache_lookup(ap) 575 struct vop_lookup_args /* { 576 struct vnode *a_dvp; 577 struct vnode **a_vpp; 578 struct componentname *a_cnp; 579 } */ *ap; 580 { 581 struct vnode *dvp, *vp; 582 int lockparent; 583 int error; 584 struct vnode **vpp = ap->a_vpp; 585 struct componentname *cnp = ap->a_cnp; 586 struct ucred *cred = cnp->cn_cred; 587 int flags = cnp->cn_flags; 588 struct thread *td = cnp->cn_thread; 589 u_long vpid; /* capability number of vnode */ 590 591 *vpp = NULL; 592 dvp = ap->a_dvp; 593 lockparent = flags & LOCKPARENT; 594 595 if (dvp->v_type != VDIR) 596 return (ENOTDIR); 597 598 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && 599 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 600 return (EROFS); 601 602 error = VOP_ACCESS(dvp, VEXEC, cred, td); 603 604 if (error) 605 return (error); 606 607 error = cache_lookup(dvp, vpp, cnp); 608 609 #ifdef LOOKUP_SHARED 610 if (!error) { 611 /* We do this because the rest of the system now expects to get 612 * a shared lock, which is later upgraded if LOCKSHARED is not 613 * set. We have so many cases here because of bugs that yield 614 * inconsistant lock states. This all badly needs to be fixed 615 */ 616 error = VOP_CACHEDLOOKUP(dvp, vpp, cnp); 617 if (!error) { 618 int flock; 619 620 flock = VOP_ISLOCKED(*vpp, td); 621 if (flock != LK_EXCLUSIVE) { 622 if (flock == 0) { 623 if ((flags & ISLASTCN) && 624 (flags & LOCKSHARED)) 625 VOP_LOCK(*vpp, LK_SHARED, td); 626 else 627 VOP_LOCK(*vpp, LK_EXCLUSIVE, td); 628 } 629 } else if ((flags & ISLASTCN) && (flags & LOCKSHARED)) 630 VOP_LOCK(*vpp, LK_DOWNGRADE, td); 631 } 632 return (error); 633 } 634 #else 635 if (!error) 636 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); 637 #endif 638 639 if (error == ENOENT) 640 return (error); 641 642 vp = *vpp; 643 vpid = vp->v_id; 644 cnp->cn_flags &= ~PDIRUNLOCK; 645 if (dvp == vp) { /* lookup on "." */ 646 VREF(vp); 647 error = 0; 648 } else if (flags & ISDOTDOT) { 649 VOP_UNLOCK(dvp, 0, td); 650 cnp->cn_flags |= PDIRUNLOCK; 651 #ifdef LOOKUP_SHARED 652 if ((flags & ISLASTCN) && (flags & LOCKSHARED)) 653 error = vget(vp, LK_SHARED, td); 654 else 655 error = vget(vp, LK_EXCLUSIVE, td); 656 #else 657 error = vget(vp, LK_EXCLUSIVE, td); 658 #endif 659 660 if (!error && lockparent && (flags & ISLASTCN)) { 661 if ((error = vn_lock(dvp, LK_EXCLUSIVE, td)) == 0) 662 cnp->cn_flags &= ~PDIRUNLOCK; 663 } 664 } else { 665 #ifdef LOOKUP_SHARED 666 if ((flags & ISLASTCN) && (flags & LOCKSHARED)) 667 error = vget(vp, LK_SHARED, td); 668 else 669 error = vget(vp, LK_EXCLUSIVE, td); 670 #else 671 error = vget(vp, LK_EXCLUSIVE, td); 672 #endif 673 if (!lockparent || error || !(flags & ISLASTCN)) { 674 VOP_UNLOCK(dvp, 0, td); 675 cnp->cn_flags |= PDIRUNLOCK; 676 } 677 } 678 /* 679 * Check that the capability number did not change 680 * while we were waiting for the lock. 681 */ 682 if (!error) { 683 if (vpid == vp->v_id) 684 return (0); 685 vput(vp); 686 if (lockparent && dvp != vp && (flags & ISLASTCN)) { 687 VOP_UNLOCK(dvp, 0, td); 688 cnp->cn_flags |= PDIRUNLOCK; 689 } 690 } 691 if (cnp->cn_flags & PDIRUNLOCK) { 692 error = vn_lock(dvp, LK_EXCLUSIVE, td); 693 if (error) 694 return (error); 695 cnp->cn_flags &= ~PDIRUNLOCK; 696 } 697 #ifdef LOOKUP_SHARED 698 error = VOP_CACHEDLOOKUP(dvp, vpp, cnp); 699 700 if (!error) { 701 int flock = 0; 702 703 flock = VOP_ISLOCKED(*vpp, td); 704 if (flock != LK_EXCLUSIVE) { 705 if (flock == 0) { 706 if ((flags & ISLASTCN) && (flags & LOCKSHARED)) 707 VOP_LOCK(*vpp, LK_SHARED, td); 708 else 709 VOP_LOCK(*vpp, LK_EXCLUSIVE, td); 710 } 711 } else if ((flags & ISLASTCN) && (flags & LOCKSHARED)) 712 VOP_LOCK(*vpp, LK_DOWNGRADE, td); 713 } 714 715 return (error); 716 #else 717 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); 718 #endif 719 } 720 721 722 #ifndef _SYS_SYSPROTO_H_ 723 struct __getcwd_args { 724 u_char *buf; 725 u_int buflen; 726 }; 727 #endif 728 729 /* 730 * XXX All of these sysctls would probably be more productive dead. 731 */ 732 static int disablecwd; 733 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, 734 "Disable the getcwd syscall"); 735 736 /* Various statistics for the getcwd syscall */ 737 static u_long numcwdcalls; STATNODE(CTLFLAG_RD, numcwdcalls, &numcwdcalls); 738 static u_long numcwdfail1; STATNODE(CTLFLAG_RD, numcwdfail1, &numcwdfail1); 739 static u_long numcwdfail2; STATNODE(CTLFLAG_RD, numcwdfail2, &numcwdfail2); 740 static u_long numcwdfail3; STATNODE(CTLFLAG_RD, numcwdfail3, &numcwdfail3); 741 static u_long numcwdfail4; STATNODE(CTLFLAG_RD, numcwdfail4, &numcwdfail4); 742 static u_long numcwdfound; STATNODE(CTLFLAG_RD, numcwdfound, &numcwdfound); 743 744 /* Implementation of the getcwd syscall */ 745 int 746 __getcwd(td, uap) 747 struct thread *td; 748 struct __getcwd_args *uap; 749 { 750 751 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen)); 752 } 753 754 int 755 kern___getcwd(struct thread *td, u_char *buf, enum uio_seg bufseg, u_int buflen) 756 { 757 char *bp, *tmpbuf; 758 int error, i, slash_prefixed; 759 struct filedesc *fdp; 760 struct namecache *ncp; 761 struct vnode *vp; 762 763 numcwdcalls++; 764 if (disablecwd) 765 return (ENODEV); 766 if (buflen < 2) 767 return (EINVAL); 768 if (buflen > MAXPATHLEN) 769 buflen = MAXPATHLEN; 770 error = 0; 771 tmpbuf = bp = malloc(buflen, M_TEMP, M_WAITOK); 772 bp += buflen - 1; 773 *bp = '\0'; 774 fdp = td->td_proc->p_fd; 775 slash_prefixed = 0; 776 FILEDESC_LOCK(fdp); 777 mp_fixme("No vnode locking done!"); 778 for (vp = fdp->fd_cdir; vp != fdp->fd_rdir && vp != rootvnode;) { 779 if (vp->v_vflag & VV_ROOT) { 780 if (vp->v_mount == NULL) { /* forced unmount */ 781 FILEDESC_UNLOCK(fdp); 782 free(tmpbuf, M_TEMP); 783 return (EBADF); 784 } 785 vp = vp->v_mount->mnt_vnodecovered; 786 continue; 787 } 788 if (vp->v_dd->v_id != vp->v_ddid) { 789 FILEDESC_UNLOCK(fdp); 790 numcwdfail1++; 791 free(tmpbuf, M_TEMP); 792 return (ENOTDIR); 793 } 794 ncp = TAILQ_FIRST(&vp->v_cache_dst); 795 if (!ncp) { 796 FILEDESC_UNLOCK(fdp); 797 numcwdfail2++; 798 free(tmpbuf, M_TEMP); 799 return (ENOENT); 800 } 801 if (ncp->nc_dvp != vp->v_dd) { 802 FILEDESC_UNLOCK(fdp); 803 numcwdfail3++; 804 free(tmpbuf, M_TEMP); 805 return (EBADF); 806 } 807 for (i = ncp->nc_nlen - 1; i >= 0; i--) { 808 if (bp == tmpbuf) { 809 FILEDESC_UNLOCK(fdp); 810 numcwdfail4++; 811 free(tmpbuf, M_TEMP); 812 return (ENOMEM); 813 } 814 *--bp = ncp->nc_name[i]; 815 } 816 if (bp == tmpbuf) { 817 FILEDESC_UNLOCK(fdp); 818 numcwdfail4++; 819 free(tmpbuf, M_TEMP); 820 return (ENOMEM); 821 } 822 *--bp = '/'; 823 slash_prefixed = 1; 824 vp = vp->v_dd; 825 } 826 FILEDESC_UNLOCK(fdp); 827 if (!slash_prefixed) { 828 if (bp == tmpbuf) { 829 numcwdfail4++; 830 free(tmpbuf, M_TEMP); 831 return (ENOMEM); 832 } 833 *--bp = '/'; 834 } 835 numcwdfound++; 836 if (bufseg == UIO_SYSSPACE) 837 bcopy(bp, buf, strlen(bp) + 1); 838 else 839 error = copyout(bp, buf, strlen(bp) + 1); 840 free(tmpbuf, M_TEMP); 841 return (error); 842 } 843 844 /* 845 * Thus begins the fullpath magic. 846 */ 847 848 #undef STATNODE 849 #define STATNODE(name) \ 850 static u_int name; \ 851 SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, "") 852 853 static int disablefullpath; 854 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0, 855 "Disable the vn_fullpath function"); 856 857 STATNODE(numfullpathcalls); 858 STATNODE(numfullpathfail1); 859 STATNODE(numfullpathfail2); 860 STATNODE(numfullpathfail3); 861 STATNODE(numfullpathfail4); 862 STATNODE(numfullpathfound); 863 864 /* 865 * Retrieve the full filesystem path that correspond to a vnode from the name 866 * cache (if available) 867 */ 868 int 869 vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf) 870 { 871 char *bp, *buf; 872 int i, slash_prefixed; 873 struct filedesc *fdp; 874 struct namecache *ncp; 875 struct vnode *vp; 876 877 numfullpathcalls++; 878 if (disablefullpath) 879 return (ENODEV); 880 if (vn == NULL) 881 return (EINVAL); 882 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 883 bp = buf + MAXPATHLEN - 1; 884 *bp = '\0'; 885 fdp = td->td_proc->p_fd; 886 slash_prefixed = 0; 887 FILEDESC_LOCK(fdp); 888 for (vp = vn; vp != fdp->fd_rdir && vp != rootvnode;) { 889 ASSERT_VOP_LOCKED(vp, "vn_fullpath"); 890 if (vp->v_vflag & VV_ROOT) { 891 if (vp->v_mount == NULL) { /* forced unmount */ 892 FILEDESC_UNLOCK(fdp); 893 free(buf, M_TEMP); 894 return (EBADF); 895 } 896 vp = vp->v_mount->mnt_vnodecovered; 897 continue; 898 } 899 if (vp != vn && vp->v_dd->v_id != vp->v_ddid) { 900 FILEDESC_UNLOCK(fdp); 901 numfullpathfail1++; 902 free(buf, M_TEMP); 903 return (ENOTDIR); 904 } 905 ncp = TAILQ_FIRST(&vp->v_cache_dst); 906 if (!ncp) { 907 FILEDESC_UNLOCK(fdp); 908 numfullpathfail2++; 909 free(buf, M_TEMP); 910 return (ENOENT); 911 } 912 if (vp != vn && ncp->nc_dvp != vp->v_dd) { 913 FILEDESC_UNLOCK(fdp); 914 numfullpathfail3++; 915 free(buf, M_TEMP); 916 return (EBADF); 917 } 918 for (i = ncp->nc_nlen - 1; i >= 0; i--) { 919 if (bp == buf) { 920 FILEDESC_UNLOCK(fdp); 921 numfullpathfail4++; 922 free(buf, M_TEMP); 923 return (ENOMEM); 924 } 925 *--bp = ncp->nc_name[i]; 926 } 927 if (bp == buf) { 928 FILEDESC_UNLOCK(fdp); 929 numfullpathfail4++; 930 free(buf, M_TEMP); 931 return (ENOMEM); 932 } 933 *--bp = '/'; 934 slash_prefixed = 1; 935 vp = ncp->nc_dvp; 936 } 937 if (!slash_prefixed) { 938 if (bp == buf) { 939 FILEDESC_UNLOCK(fdp); 940 numfullpathfail4++; 941 free(buf, M_TEMP); 942 return (ENOMEM); 943 } 944 *--bp = '/'; 945 } 946 FILEDESC_UNLOCK(fdp); 947 numfullpathfound++; 948 *retbuf = bp; 949 *freebuf = buf; 950 return (0); 951 } 952