Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/kern/vfs_cache.c
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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: releng/5.3/sys/kern/vfs_cache.c 136588 2004-10-16 08:43:07Z cvs2svn $"); 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 struct mtx cache_lock; 113 MTX_SYSINIT(vfscache, &cache_lock, "Name Cache", MTX_DEF); 114 115 #define CACHE_LOCK() mtx_lock(&cache_lock) 116 #define CACHE_UNLOCK() mtx_unlock(&cache_lock) 117 118 /* 119 * UMA zones for the VFS cache. 120 * 121 * The small cache is used for entries with short names, which are the 122 * most common. The large cache is used for entries which are too big to 123 * fit in the small cache. 124 */ 125 static uma_zone_t cache_zone_small; 126 static uma_zone_t cache_zone_large; 127 128 #define CACHE_PATH_CUTOFF 32 129 #define CACHE_ZONE_SMALL (sizeof(struct namecache) + CACHE_PATH_CUTOFF) 130 #define CACHE_ZONE_LARGE (sizeof(struct namecache) + NAME_MAX) 131 132 #define cache_alloc(len) uma_zalloc(((len) <= CACHE_PATH_CUTOFF) ? \ 133 cache_zone_small : cache_zone_large, M_WAITOK) 134 #define cache_free(ncp) do { \ 135 if (ncp != NULL) \ 136 uma_zfree(((ncp)->nc_nlen <= CACHE_PATH_CUTOFF) ? \ 137 cache_zone_small : cache_zone_large, (ncp)); \ 138 } while (0) 139 140 static int doingcache = 1; /* 1 => enable the cache */ 141 SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0, ""); 142 143 /* Export size information to userland */ 144 SYSCTL_INT(_debug, OID_AUTO, vnsize, CTLFLAG_RD, 0, sizeof(struct vnode), ""); 145 SYSCTL_INT(_debug, OID_AUTO, ncsize, CTLFLAG_RD, 0, sizeof(struct namecache), ""); 146 147 /* 148 * The new name cache statistics 149 */ 150 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, int locked); 172 173 static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); 174 175 /* 176 * Flags in namecache.nc_flag 177 */ 178 #define NCF_WHITE 1 179 180 /* 181 * Grab an atomic snapshot of the name cache hash chain lengths 182 */ 183 SYSCTL_NODE(_debug, OID_AUTO, hashstat, CTLFLAG_RW, NULL, "hash table stats"); 184 185 static int 186 sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS) 187 { 188 int error; 189 struct nchashhead *ncpp; 190 struct namecache *ncp; 191 int n_nchash; 192 int count; 193 194 n_nchash = nchash + 1; /* nchash is max index, not count */ 195 if (!req->oldptr) 196 return SYSCTL_OUT(req, 0, n_nchash * sizeof(int)); 197 198 /* Scan hash tables for applicable entries */ 199 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { 200 count = 0; 201 LIST_FOREACH(ncp, ncpp, nc_hash) { 202 count++; 203 } 204 error = SYSCTL_OUT(req, &count, sizeof(count)); 205 if (error) 206 return (error); 207 } 208 return (0); 209 } 210 SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD, 211 0, 0, sysctl_debug_hashstat_rawnchash, "S,int", "nchash chain lengths"); 212 213 static int 214 sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS) 215 { 216 int error; 217 struct nchashhead *ncpp; 218 struct namecache *ncp; 219 int n_nchash; 220 int count, maxlength, used, pct; 221 222 if (!req->oldptr) 223 return SYSCTL_OUT(req, 0, 4 * sizeof(int)); 224 225 n_nchash = nchash + 1; /* nchash is max index, not count */ 226 used = 0; 227 maxlength = 0; 228 229 /* Scan hash tables for applicable entries */ 230 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { 231 count = 0; 232 LIST_FOREACH(ncp, ncpp, nc_hash) { 233 count++; 234 } 235 if (count) 236 used++; 237 if (maxlength < count) 238 maxlength = count; 239 } 240 n_nchash = nchash + 1; 241 pct = (used * 100 * 100) / n_nchash; 242 error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash)); 243 if (error) 244 return (error); 245 error = SYSCTL_OUT(req, &used, sizeof(used)); 246 if (error) 247 return (error); 248 error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength)); 249 if (error) 250 return (error); 251 error = SYSCTL_OUT(req, &pct, sizeof(pct)); 252 if (error) 253 return (error); 254 return (0); 255 } 256 SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD, 257 0, 0, sysctl_debug_hashstat_nchash, "I", "nchash chain lengths"); 258 259 /* 260 * cache_zap(): 261 * 262 * Removes a namecache entry from cache, whether it contains an actual 263 * pointer to a vnode or if it is just a negative cache entry. 264 */ 265 static void 266 cache_zap(ncp, locked) 267 struct namecache *ncp; 268 int locked; 269 { 270 struct vnode *vp; 271 272 vp = NULL; 273 if (!locked) 274 CACHE_LOCK(); 275 LIST_REMOVE(ncp, nc_hash); 276 LIST_REMOVE(ncp, nc_src); 277 if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) { 278 vp = ncp->nc_dvp; 279 numcachehv--; 280 } 281 if (ncp->nc_vp) { 282 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst); 283 } else { 284 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 285 numneg--; 286 } 287 numcache--; 288 CACHE_UNLOCK(); 289 cache_free(ncp); 290 if (vp) 291 vdrop(vp); 292 if (locked) 293 CACHE_LOCK(); 294 } 295 296 /* 297 * cache_leaf_test() 298 * 299 * Test whether this (directory) vnode's namei cache entry contains 300 * subdirectories or not. Used to determine whether the directory is 301 * a leaf in the namei cache or not. Note: the directory may still 302 * contain files in the namei cache. 303 * 304 * Returns 0 if the directory is a leaf, -1 if it isn't. 305 */ 306 int 307 cache_leaf_test(struct vnode *vp) 308 { 309 struct namecache *ncpc; 310 int leaf; 311 312 leaf = 0; 313 CACHE_LOCK(); 314 for (ncpc = LIST_FIRST(&vp->v_cache_src); 315 ncpc != NULL; 316 ncpc = LIST_NEXT(ncpc, nc_src) 317 ) { 318 if (ncpc->nc_vp != NULL && ncpc->nc_vp->v_type == VDIR) { 319 leaf = -1; 320 break; 321 } 322 } 323 CACHE_UNLOCK(); 324 return (leaf); 325 } 326 327 /* 328 * Lookup an entry in the cache 329 * 330 * Lookup is called with dvp pointing to the directory to search, 331 * cnp pointing to the name of the entry being sought. If the lookup 332 * succeeds, the vnode is returned in *vpp, and a status of -1 is 333 * returned. If the lookup determines that the name does not exist 334 * (negative cacheing), a status of ENOENT is returned. If the lookup 335 * fails, a status of zero is returned. 336 */ 337 338 int 339 cache_lookup(dvp, vpp, cnp) 340 struct vnode *dvp; 341 struct vnode **vpp; 342 struct componentname *cnp; 343 { 344 struct namecache *ncp; 345 u_int32_t hash; 346 347 if (!doingcache) { 348 cnp->cn_flags &= ~MAKEENTRY; 349 return (0); 350 } 351 352 CACHE_LOCK(); 353 numcalls++; 354 355 if (cnp->cn_nameptr[0] == '.') { 356 if (cnp->cn_namelen == 1) { 357 *vpp = dvp; 358 dothits++; 359 CACHE_UNLOCK(); 360 return (-1); 361 } 362 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 363 dotdothits++; 364 if (dvp->v_dd->v_id != dvp->v_ddid || 365 (cnp->cn_flags & MAKEENTRY) == 0) { 366 dvp->v_ddid = 0; 367 CACHE_UNLOCK(); 368 return (0); 369 } 370 *vpp = dvp->v_dd; 371 CACHE_UNLOCK(); 372 return (-1); 373 } 374 } 375 376 hash = fnv_32_buf(cnp->cn_nameptr, cnp->cn_namelen, FNV1_32_INIT); 377 hash = fnv_32_buf(&dvp->v_id, sizeof(dvp->v_id), hash); 378 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 379 numchecks++; 380 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 381 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 382 break; 383 } 384 385 /* We failed to find an entry */ 386 if (ncp == 0) { 387 if ((cnp->cn_flags & MAKEENTRY) == 0) { 388 nummisszap++; 389 } else { 390 nummiss++; 391 } 392 nchstats.ncs_miss++; 393 CACHE_UNLOCK(); 394 return (0); 395 } 396 397 /* We don't want to have an entry, so dump it */ 398 if ((cnp->cn_flags & MAKEENTRY) == 0) { 399 numposzaps++; 400 nchstats.ncs_badhits++; 401 CACHE_UNLOCK(); 402 cache_zap(ncp, 0); 403 return (0); 404 } 405 406 /* We found a "positive" match, return the vnode */ 407 if (ncp->nc_vp) { 408 numposhits++; 409 nchstats.ncs_goodhits++; 410 *vpp = ncp->nc_vp; 411 CACHE_UNLOCK(); 412 return (-1); 413 } 414 415 /* We found a negative match, and want to create it, so purge */ 416 if (cnp->cn_nameiop == CREATE) { 417 numnegzaps++; 418 nchstats.ncs_badhits++; 419 CACHE_UNLOCK(); 420 cache_zap(ncp, 0); 421 return (0); 422 } 423 424 numneghits++; 425 /* 426 * We found a "negative" match, so we shift it to the end of 427 * the "negative" cache entries queue to satisfy LRU. Also, 428 * check to see if the entry is a whiteout; indicate this to 429 * the componentname, if so. 430 */ 431 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 432 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 433 nchstats.ncs_neghits++; 434 if (ncp->nc_flag & NCF_WHITE) 435 cnp->cn_flags |= ISWHITEOUT; 436 CACHE_UNLOCK(); 437 return (ENOENT); 438 } 439 440 /* 441 * Add an entry to the cache. 442 */ 443 void 444 cache_enter(dvp, vp, cnp) 445 struct vnode *dvp; 446 struct vnode *vp; 447 struct componentname *cnp; 448 { 449 struct namecache *ncp; 450 struct nchashhead *ncpp; 451 u_int32_t hash; 452 int hold; 453 int zap; 454 int len; 455 456 if (!doingcache) 457 return; 458 459 if (cnp->cn_nameptr[0] == '.') { 460 if (cnp->cn_namelen == 1) { 461 return; 462 } 463 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 464 if (vp) { 465 dvp->v_dd = vp; 466 dvp->v_ddid = vp->v_id; 467 } else { 468 dvp->v_dd = dvp; 469 dvp->v_ddid = 0; 470 } 471 return; 472 } 473 } 474 475 hold = 0; 476 zap = 0; 477 ncp = cache_alloc(cnp->cn_namelen); 478 CACHE_LOCK(); 479 numcache++; 480 if (!vp) { 481 numneg++; 482 ncp->nc_flag = cnp->cn_flags & ISWHITEOUT ? NCF_WHITE : 0; 483 } else if (vp->v_type == VDIR) { 484 vp->v_dd = dvp; 485 vp->v_ddid = dvp->v_id; 486 } 487 488 /* 489 * Set the rest of the namecache entry elements, calculate it's 490 * hash key and insert it into the appropriate chain within 491 * the cache entries table. 492 */ 493 ncp->nc_vp = vp; 494 ncp->nc_dvp = dvp; 495 len = ncp->nc_nlen = cnp->cn_namelen; 496 hash = fnv_32_buf(cnp->cn_nameptr, len, FNV1_32_INIT); 497 bcopy(cnp->cn_nameptr, ncp->nc_name, len); 498 hash = fnv_32_buf(&dvp->v_id, sizeof(dvp->v_id), hash); 499 ncpp = NCHHASH(hash); 500 LIST_INSERT_HEAD(ncpp, ncp, nc_hash); 501 if (LIST_EMPTY(&dvp->v_cache_src)) { 502 hold = 1; 503 numcachehv++; 504 } 505 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); 506 /* 507 * If the entry is "negative", we place it into the 508 * "negative" cache queue, otherwise, we place it into the 509 * destination vnode's cache entries queue. 510 */ 511 if (vp) { 512 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); 513 } else { 514 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 515 } 516 if (numneg * ncnegfactor > numcache) { 517 ncp = TAILQ_FIRST(&ncneg); 518 zap = 1; 519 } 520 CACHE_UNLOCK(); 521 if (hold) 522 vhold(dvp); 523 if (zap) 524 cache_zap(ncp, 0); 525 } 526 527 /* 528 * Name cache initialization, from vfs_init() when we are booting 529 */ 530 static void 531 nchinit(void *dummy __unused) 532 { 533 534 TAILQ_INIT(&ncneg); 535 536 cache_zone_small = uma_zcreate("S VFS Cache", CACHE_ZONE_SMALL, NULL, 537 NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 538 cache_zone_large = uma_zcreate("L VFS Cache", CACHE_ZONE_LARGE, NULL, 539 NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 540 541 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash); 542 } 543 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL) 544 545 546 /* 547 * Invalidate all entries to a particular vnode. 548 * 549 * Remove all entries in the namecache relating to this vnode and 550 * change the v_id. We take the v_id from a global counter, since 551 * it becomes a handy sequence number in crash-dumps that way. 552 * No valid vnode will ever have (v_id == 0). 553 * 554 * XXX: Only time and the size of v_id prevents this from failing: 555 * XXX: In theory we should hunt down all (struct vnode*, v_id) 556 * XXX: soft references and nuke them, at least on the global 557 * XXX: v_id wraparound. The period of resistance can be extended 558 * XXX: by incrementing each vnodes v_id individually instead of 559 * XXX: using the global v_id. 560 */ 561 562 /* 563 * XXX This is sometimes called when a vnode may still be re-used, in which 564 * case v_dd may be invalid. Need to look this up. 565 */ 566 void 567 cache_purge(vp) 568 struct vnode *vp; 569 { 570 static u_long nextid; 571 572 CACHE_LOCK(); 573 while (!LIST_EMPTY(&vp->v_cache_src)) 574 cache_zap(LIST_FIRST(&vp->v_cache_src), 1); 575 while (!TAILQ_EMPTY(&vp->v_cache_dst)) 576 cache_zap(TAILQ_FIRST(&vp->v_cache_dst), 1); 577 578 do 579 nextid++; 580 while (nextid == vp->v_id || !nextid); 581 vp->v_id = nextid; 582 vp->v_dd = vp; 583 vp->v_ddid = 0; 584 CACHE_UNLOCK(); 585 } 586 587 /* 588 * Flush all entries referencing a particular filesystem. 589 * 590 * Since we need to check it anyway, we will flush all the invalid 591 * entries at the same time. 592 */ 593 void 594 cache_purgevfs(mp) 595 struct mount *mp; 596 { 597 struct nchashhead *ncpp; 598 struct namecache *ncp, *nnp; 599 struct nchashhead mplist; 600 601 LIST_INIT(&mplist); 602 ncp = NULL; 603 604 /* Scan hash tables for applicable entries */ 605 CACHE_LOCK(); 606 for (ncpp = &nchashtbl[nchash]; ncpp >= nchashtbl; ncpp--) { 607 for (ncp = LIST_FIRST(ncpp); ncp != 0; ncp = nnp) { 608 nnp = LIST_NEXT(ncp, nc_hash); 609 if (ncp->nc_dvp->v_mount == mp) { 610 LIST_REMOVE(ncp, nc_hash); 611 LIST_INSERT_HEAD(&mplist, ncp, nc_hash); 612 } 613 } 614 } 615 CACHE_UNLOCK(); 616 while (!LIST_EMPTY(&mplist)) 617 cache_zap(LIST_FIRST(&mplist), 0); 618 } 619 620 /* 621 * Perform canonical checks and cache lookup and pass on to filesystem 622 * through the vop_cachedlookup only if needed. 623 */ 624 625 int 626 vfs_cache_lookup(ap) 627 struct vop_lookup_args /* { 628 struct vnode *a_dvp; 629 struct vnode **a_vpp; 630 struct componentname *a_cnp; 631 } */ *ap; 632 { 633 struct vnode *dvp, *vp; 634 int lockparent; 635 int error; 636 struct vnode **vpp = ap->a_vpp; 637 struct componentname *cnp = ap->a_cnp; 638 struct ucred *cred = cnp->cn_cred; 639 int flags = cnp->cn_flags; 640 struct thread *td = cnp->cn_thread; 641 u_long vpid; /* capability number of vnode */ 642 643 *vpp = NULL; 644 dvp = ap->a_dvp; 645 lockparent = flags & LOCKPARENT; 646 647 if (dvp->v_type != VDIR) 648 return (ENOTDIR); 649 650 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && 651 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 652 return (EROFS); 653 654 error = VOP_ACCESS(dvp, VEXEC, cred, td); 655 656 if (error) 657 return (error); 658 659 error = cache_lookup(dvp, vpp, cnp); 660 661 #ifdef LOOKUP_SHARED 662 if (!error) { 663 /* We do this because the rest of the system now expects to get 664 * a shared lock, which is later upgraded if LOCKSHARED is not 665 * set. We have so many cases here because of bugs that yield 666 * inconsistant lock states. This all badly needs to be fixed 667 */ 668 error = VOP_CACHEDLOOKUP(dvp, vpp, cnp); 669 if (!error) { 670 int flock; 671 672 flock = VOP_ISLOCKED(*vpp, td); 673 if (flock != LK_EXCLUSIVE) { 674 if (flock == 0) { 675 if ((flags & ISLASTCN) && 676 (flags & LOCKSHARED)) 677 VOP_LOCK(*vpp, LK_SHARED, td); 678 else 679 VOP_LOCK(*vpp, LK_EXCLUSIVE, td); 680 } 681 } else if ((flags & ISLASTCN) && (flags & LOCKSHARED)) 682 VOP_LOCK(*vpp, LK_DOWNGRADE, td); 683 } 684 return (error); 685 } 686 #else 687 if (!error) 688 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); 689 #endif 690 691 if (error == ENOENT) 692 return (error); 693 694 vp = *vpp; 695 vpid = vp->v_id; 696 cnp->cn_flags &= ~PDIRUNLOCK; 697 if (dvp == vp) { /* lookup on "." */ 698 VREF(vp); 699 error = 0; 700 } else if (flags & ISDOTDOT) { 701 VOP_UNLOCK(dvp, 0, td); 702 cnp->cn_flags |= PDIRUNLOCK; 703 #ifdef LOOKUP_SHARED 704 if ((flags & ISLASTCN) && (flags & LOCKSHARED)) 705 error = vget(vp, LK_SHARED, td); 706 else 707 error = vget(vp, LK_EXCLUSIVE, td); 708 #else 709 error = vget(vp, LK_EXCLUSIVE, td); 710 #endif 711 712 if (!error && lockparent && (flags & ISLASTCN)) { 713 if ((error = vn_lock(dvp, LK_EXCLUSIVE, td)) == 0) 714 cnp->cn_flags &= ~PDIRUNLOCK; 715 } 716 } else { 717 #ifdef LOOKUP_SHARED 718 if ((flags & ISLASTCN) && (flags & LOCKSHARED)) 719 error = vget(vp, LK_SHARED, td); 720 else 721 error = vget(vp, LK_EXCLUSIVE, td); 722 #else 723 error = vget(vp, LK_EXCLUSIVE, td); 724 #endif 725 if (!lockparent || error || !(flags & ISLASTCN)) { 726 VOP_UNLOCK(dvp, 0, td); 727 cnp->cn_flags |= PDIRUNLOCK; 728 } 729 } 730 /* 731 * Check that the capability number did not change 732 * while we were waiting for the lock. 733 */ 734 if (!error) { 735 if (vpid == vp->v_id) 736 return (0); 737 vput(vp); 738 if (lockparent && dvp != vp && (flags & ISLASTCN)) { 739 VOP_UNLOCK(dvp, 0, td); 740 cnp->cn_flags |= PDIRUNLOCK; 741 } 742 } 743 if (cnp->cn_flags & PDIRUNLOCK) { 744 error = vn_lock(dvp, LK_EXCLUSIVE, td); 745 if (error) 746 return (error); 747 cnp->cn_flags &= ~PDIRUNLOCK; 748 } 749 #ifdef LOOKUP_SHARED 750 error = VOP_CACHEDLOOKUP(dvp, vpp, cnp); 751 752 if (!error) { 753 int flock = 0; 754 755 flock = VOP_ISLOCKED(*vpp, td); 756 if (flock != LK_EXCLUSIVE) { 757 if (flock == 0) { 758 if ((flags & ISLASTCN) && (flags & LOCKSHARED)) 759 VOP_LOCK(*vpp, LK_SHARED, td); 760 else 761 VOP_LOCK(*vpp, LK_EXCLUSIVE, td); 762 } 763 } else if ((flags & ISLASTCN) && (flags & LOCKSHARED)) 764 VOP_LOCK(*vpp, LK_DOWNGRADE, td); 765 } 766 767 return (error); 768 #else 769 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); 770 #endif 771 } 772 773 774 #ifndef _SYS_SYSPROTO_H_ 775 struct __getcwd_args { 776 u_char *buf; 777 u_int buflen; 778 }; 779 #endif 780 781 /* 782 * XXX All of these sysctls would probably be more productive dead. 783 */ 784 static int disablecwd; 785 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, 786 "Disable the getcwd syscall"); 787 788 /* Various statistics for the getcwd syscall */ 789 static u_long numcwdcalls; STATNODE(CTLFLAG_RD, numcwdcalls, &numcwdcalls); 790 static u_long numcwdfail1; STATNODE(CTLFLAG_RD, numcwdfail1, &numcwdfail1); 791 static u_long numcwdfail2; STATNODE(CTLFLAG_RD, numcwdfail2, &numcwdfail2); 792 static u_long numcwdfail3; STATNODE(CTLFLAG_RD, numcwdfail3, &numcwdfail3); 793 static u_long numcwdfail4; STATNODE(CTLFLAG_RD, numcwdfail4, &numcwdfail4); 794 static u_long numcwdfound; STATNODE(CTLFLAG_RD, numcwdfound, &numcwdfound); 795 796 /* Implementation of the getcwd syscall */ 797 int 798 __getcwd(td, uap) 799 struct thread *td; 800 struct __getcwd_args *uap; 801 { 802 803 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen)); 804 } 805 806 int 807 kern___getcwd(struct thread *td, u_char *buf, enum uio_seg bufseg, u_int buflen) 808 { 809 char *bp, *tmpbuf; 810 int error, i, slash_prefixed; 811 struct filedesc *fdp; 812 struct namecache *ncp; 813 struct vnode *vp; 814 815 numcwdcalls++; 816 if (disablecwd) 817 return (ENODEV); 818 if (buflen < 2) 819 return (EINVAL); 820 if (buflen > MAXPATHLEN) 821 buflen = MAXPATHLEN; 822 error = 0; 823 tmpbuf = bp = malloc(buflen, M_TEMP, M_WAITOK); 824 bp += buflen - 1; 825 *bp = '\0'; 826 fdp = td->td_proc->p_fd; 827 slash_prefixed = 0; 828 FILEDESC_LOCK(fdp); 829 for (vp = fdp->fd_cdir; vp != fdp->fd_rdir && vp != rootvnode;) { 830 if (vp->v_vflag & VV_ROOT) { 831 if (vp->v_mount == NULL) { /* forced unmount */ 832 FILEDESC_UNLOCK(fdp); 833 free(tmpbuf, M_TEMP); 834 return (EBADF); 835 } 836 vp = vp->v_mount->mnt_vnodecovered; 837 continue; 838 } 839 if (vp->v_dd->v_id != vp->v_ddid) { 840 FILEDESC_UNLOCK(fdp); 841 numcwdfail1++; 842 free(tmpbuf, M_TEMP); 843 return (ENOTDIR); 844 } 845 CACHE_LOCK(); 846 ncp = TAILQ_FIRST(&vp->v_cache_dst); 847 if (!ncp) { 848 numcwdfail2++; 849 CACHE_UNLOCK(); 850 FILEDESC_UNLOCK(fdp); 851 free(tmpbuf, M_TEMP); 852 return (ENOENT); 853 } 854 if (ncp->nc_dvp != vp->v_dd) { 855 numcwdfail3++; 856 CACHE_UNLOCK(); 857 FILEDESC_UNLOCK(fdp); 858 free(tmpbuf, M_TEMP); 859 return (EBADF); 860 } 861 for (i = ncp->nc_nlen - 1; i >= 0; i--) { 862 if (bp == tmpbuf) { 863 numcwdfail4++; 864 CACHE_UNLOCK(); 865 FILEDESC_UNLOCK(fdp); 866 free(tmpbuf, M_TEMP); 867 return (ENOMEM); 868 } 869 *--bp = ncp->nc_name[i]; 870 } 871 if (bp == tmpbuf) { 872 numcwdfail4++; 873 CACHE_UNLOCK(); 874 FILEDESC_UNLOCK(fdp); 875 free(tmpbuf, M_TEMP); 876 return (ENOMEM); 877 } 878 *--bp = '/'; 879 slash_prefixed = 1; 880 vp = vp->v_dd; 881 CACHE_UNLOCK(); 882 } 883 FILEDESC_UNLOCK(fdp); 884 if (!slash_prefixed) { 885 if (bp == tmpbuf) { 886 numcwdfail4++; 887 free(tmpbuf, M_TEMP); 888 return (ENOMEM); 889 } 890 *--bp = '/'; 891 } 892 numcwdfound++; 893 if (bufseg == UIO_SYSSPACE) 894 bcopy(bp, buf, strlen(bp) + 1); 895 else 896 error = copyout(bp, buf, strlen(bp) + 1); 897 free(tmpbuf, M_TEMP); 898 return (error); 899 } 900 901 /* 902 * Thus begins the fullpath magic. 903 */ 904 905 #undef STATNODE 906 #define STATNODE(name) \ 907 static u_int name; \ 908 SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, "") 909 910 static int disablefullpath; 911 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0, 912 "Disable the vn_fullpath function"); 913 914 STATNODE(numfullpathcalls); 915 STATNODE(numfullpathfail1); 916 STATNODE(numfullpathfail2); 917 STATNODE(numfullpathfail3); 918 STATNODE(numfullpathfail4); 919 STATNODE(numfullpathfound); 920 921 /* 922 * Retrieve the full filesystem path that correspond to a vnode from the name 923 * cache (if available) 924 */ 925 int 926 vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf) 927 { 928 char *bp, *buf; 929 int i, slash_prefixed; 930 struct filedesc *fdp; 931 struct namecache *ncp; 932 struct vnode *vp; 933 934 numfullpathcalls++; 935 if (disablefullpath) 936 return (ENODEV); 937 if (vn == NULL) 938 return (EINVAL); 939 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 940 bp = buf + MAXPATHLEN - 1; 941 *bp = '\0'; 942 fdp = td->td_proc->p_fd; 943 slash_prefixed = 0; 944 ASSERT_VOP_LOCKED(vn, "vn_fullpath"); 945 FILEDESC_LOCK(fdp); 946 for (vp = vn; vp != fdp->fd_rdir && vp != rootvnode;) { 947 if (vp->v_vflag & VV_ROOT) { 948 if (vp->v_mount == NULL) { /* forced unmount */ 949 FILEDESC_UNLOCK(fdp); 950 free(buf, M_TEMP); 951 return (EBADF); 952 } 953 vp = vp->v_mount->mnt_vnodecovered; 954 continue; 955 } 956 if (vp != vn && vp->v_dd->v_id != vp->v_ddid) { 957 FILEDESC_UNLOCK(fdp); 958 free(buf, M_TEMP); 959 numfullpathfail1++; 960 return (ENOTDIR); 961 } 962 CACHE_LOCK(); 963 ncp = TAILQ_FIRST(&vp->v_cache_dst); 964 if (!ncp) { 965 numfullpathfail2++; 966 CACHE_UNLOCK(); 967 FILEDESC_UNLOCK(fdp); 968 free(buf, M_TEMP); 969 return (ENOENT); 970 } 971 if (vp != vn && ncp->nc_dvp != vp->v_dd) { 972 numfullpathfail3++; 973 CACHE_UNLOCK(); 974 FILEDESC_UNLOCK(fdp); 975 free(buf, M_TEMP); 976 return (EBADF); 977 } 978 for (i = ncp->nc_nlen - 1; i >= 0; i--) { 979 if (bp == buf) { 980 numfullpathfail4++; 981 CACHE_UNLOCK(); 982 FILEDESC_UNLOCK(fdp); 983 free(buf, M_TEMP); 984 return (ENOMEM); 985 } 986 *--bp = ncp->nc_name[i]; 987 } 988 if (bp == buf) { 989 numfullpathfail4++; 990 CACHE_UNLOCK(); 991 FILEDESC_UNLOCK(fdp); 992 free(buf, M_TEMP); 993 return (ENOMEM); 994 } 995 *--bp = '/'; 996 slash_prefixed = 1; 997 vp = ncp->nc_dvp; 998 CACHE_UNLOCK(); 999 } 1000 if (!slash_prefixed) { 1001 if (bp == buf) { 1002 numfullpathfail4++; 1003 FILEDESC_UNLOCK(fdp); 1004 free(buf, M_TEMP); 1005 return (ENOMEM); 1006 } 1007 *--bp = '/'; 1008 } 1009 FILEDESC_UNLOCK(fdp); 1010 numfullpathfound++; 1011 *retbuf = bp; 1012 *freebuf = buf; 1013 return (0); 1014 }
Cache object: 068faf5d7d84e72668b6ecd336d6e365
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