Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]
FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_cache.c
Version:
- FREEBSD - FREEBSD-13-STABLE - FREEBSD-13-0 - FREEBSD-12-STABLE - FREEBSD-12-0 - FREEBSD-11-STABLE - FREEBSD-11-0 - FREEBSD-10-STABLE - FREEBSD-10-0 - FREEBSD-9-STABLE - FREEBSD-9-0 - FREEBSD-8-STABLE - FREEBSD-8-0 - FREEBSD-7-STABLE - FREEBSD-7-0 - FREEBSD-6-STABLE - FREEBSD-6-0 - FREEBSD-5-STABLE - FREEBSD-5-0 - FREEBSD-4-STABLE - FREEBSD-3-STABLE - FREEBSD22 - l41 - OPENBSD - linux-2.6 - MK84 - PLAN9 - xnu-8792
SearchContext: - none - 3 - 10
SearchContext: - none - 3 - 10
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, 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 static SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, "Name cache statistics"); 151 #define STATNODE(mode, name, var) \ 152 SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, mode, var, 0, ""); 153 STATNODE(CTLFLAG_RD, numneg, &numneg); 154 STATNODE(CTLFLAG_RD, numcache, &numcache); 155 static u_long numcalls; STATNODE(CTLFLAG_RD, numcalls, &numcalls); 156 static u_long dothits; STATNODE(CTLFLAG_RD, dothits, &dothits); 157 static u_long dotdothits; STATNODE(CTLFLAG_RD, dotdothits, &dotdothits); 158 static u_long numchecks; STATNODE(CTLFLAG_RD, numchecks, &numchecks); 159 static u_long nummiss; STATNODE(CTLFLAG_RD, nummiss, &nummiss); 160 static u_long nummisszap; STATNODE(CTLFLAG_RD, nummisszap, &nummisszap); 161 static u_long numposzaps; STATNODE(CTLFLAG_RD, numposzaps, &numposzaps); 162 static u_long numposhits; STATNODE(CTLFLAG_RD, numposhits, &numposhits); 163 static u_long numnegzaps; STATNODE(CTLFLAG_RD, numnegzaps, &numnegzaps); 164 static u_long numneghits; STATNODE(CTLFLAG_RD, numneghits, &numneghits); 165 166 SYSCTL_OPAQUE(_vfs_cache, OID_AUTO, nchstats, CTLFLAG_RD, &nchstats, 167 sizeof(nchstats), "LU", "VFS cache effectiveness statistics"); 168 169 170 171 static void cache_zap(struct namecache *ncp); 172 static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 173 char *buf, char **retbuf, u_int buflen); 174 175 static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); 176 177 /* 178 * Flags in namecache.nc_flag 179 */ 180 #define NCF_WHITE 1 181 182 /* 183 * Grab an atomic snapshot of the name cache hash chain lengths 184 */ 185 SYSCTL_NODE(_debug, OID_AUTO, hashstat, CTLFLAG_RW, NULL, "hash table stats"); 186 187 static int 188 sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS) 189 { 190 int error; 191 struct nchashhead *ncpp; 192 struct namecache *ncp; 193 int n_nchash; 194 int count; 195 196 n_nchash = nchash + 1; /* nchash is max index, not count */ 197 if (!req->oldptr) 198 return SYSCTL_OUT(req, 0, n_nchash * sizeof(int)); 199 200 /* Scan hash tables for applicable entries */ 201 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { 202 count = 0; 203 LIST_FOREACH(ncp, ncpp, nc_hash) { 204 count++; 205 } 206 error = SYSCTL_OUT(req, &count, sizeof(count)); 207 if (error) 208 return (error); 209 } 210 return (0); 211 } 212 SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD, 213 0, 0, sysctl_debug_hashstat_rawnchash, "S,int", "nchash chain lengths"); 214 215 static int 216 sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS) 217 { 218 int error; 219 struct nchashhead *ncpp; 220 struct namecache *ncp; 221 int n_nchash; 222 int count, maxlength, used, pct; 223 224 if (!req->oldptr) 225 return SYSCTL_OUT(req, 0, 4 * sizeof(int)); 226 227 n_nchash = nchash + 1; /* nchash is max index, not count */ 228 used = 0; 229 maxlength = 0; 230 231 /* Scan hash tables for applicable entries */ 232 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { 233 count = 0; 234 LIST_FOREACH(ncp, ncpp, nc_hash) { 235 count++; 236 } 237 if (count) 238 used++; 239 if (maxlength < count) 240 maxlength = count; 241 } 242 n_nchash = nchash + 1; 243 pct = (used * 100 * 100) / n_nchash; 244 error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash)); 245 if (error) 246 return (error); 247 error = SYSCTL_OUT(req, &used, sizeof(used)); 248 if (error) 249 return (error); 250 error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength)); 251 if (error) 252 return (error); 253 error = SYSCTL_OUT(req, &pct, sizeof(pct)); 254 if (error) 255 return (error); 256 return (0); 257 } 258 SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD, 259 0, 0, sysctl_debug_hashstat_nchash, "I", "nchash chain lengths"); 260 261 /* 262 * cache_zap(): 263 * 264 * Removes a namecache entry from cache, whether it contains an actual 265 * pointer to a vnode or if it is just a negative cache entry. 266 */ 267 static void 268 cache_zap(ncp) 269 struct namecache *ncp; 270 { 271 struct vnode *vp; 272 273 mtx_assert(&cache_lock, MA_OWNED); 274 CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp, ncp->nc_vp); 275 vp = NULL; 276 LIST_REMOVE(ncp, nc_hash); 277 LIST_REMOVE(ncp, nc_src); 278 if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) { 279 vp = ncp->nc_dvp; 280 numcachehv--; 281 } 282 if (ncp->nc_vp) { 283 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst); 284 ncp->nc_vp->v_dd = NULL; 285 } else { 286 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 287 numneg--; 288 } 289 numcache--; 290 cache_free(ncp); 291 if (vp) 292 vdrop(vp); 293 } 294 295 /* 296 * cache_leaf_test() 297 * 298 * Test whether this (directory) vnode's namei cache entry contains 299 * subdirectories or not. Used to determine whether the directory is 300 * a leaf in the namei cache or not. Note: the directory may still 301 * contain files in the namei cache. 302 * 303 * Returns 0 if the directory is a leaf, -1 if it isn't. 304 */ 305 int 306 cache_leaf_test(struct vnode *vp) 307 { 308 struct namecache *ncpc; 309 int leaf; 310 311 leaf = 0; 312 CACHE_LOCK(); 313 for (ncpc = LIST_FIRST(&vp->v_cache_src); 314 ncpc != NULL; 315 ncpc = LIST_NEXT(ncpc, nc_src) 316 ) { 317 if (ncpc->nc_vp != NULL && ncpc->nc_vp->v_type == VDIR) { 318 leaf = -1; 319 break; 320 } 321 } 322 CACHE_UNLOCK(); 323 return (leaf); 324 } 325 326 /* 327 * Lookup an entry in the cache 328 * 329 * Lookup is called with dvp pointing to the directory to search, 330 * cnp pointing to the name of the entry being sought. If the lookup 331 * succeeds, the vnode is returned in *vpp, and a status of -1 is 332 * returned. If the lookup determines that the name does not exist 333 * (negative cacheing), a status of ENOENT is returned. If the lookup 334 * fails, a status of zero is returned. 335 * 336 * vpp is locked and ref'd on return. If we're looking up DOTDOT, dvp is 337 * unlocked. If we're looking up . an extra ref is taken, but the lock is 338 * not recursively acquired. 339 */ 340 341 int 342 cache_lookup(dvp, vpp, cnp) 343 struct vnode *dvp; 344 struct vnode **vpp; 345 struct componentname *cnp; 346 { 347 struct namecache *ncp; 348 u_int32_t hash; 349 int error; 350 351 if (!doingcache) { 352 cnp->cn_flags &= ~MAKEENTRY; 353 return (0); 354 } 355 retry: 356 CACHE_LOCK(); 357 numcalls++; 358 359 if (cnp->cn_nameptr[0] == '.') { 360 if (cnp->cn_namelen == 1) { 361 *vpp = dvp; 362 CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .", 363 dvp, cnp->cn_nameptr); 364 dothits++; 365 goto success; 366 } 367 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 368 dotdothits++; 369 if (dvp->v_dd == NULL || 370 (cnp->cn_flags & MAKEENTRY) == 0) { 371 CACHE_UNLOCK(); 372 return (0); 373 } 374 *vpp = dvp->v_dd; 375 CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..", 376 dvp, cnp->cn_nameptr, *vpp); 377 goto success; 378 } 379 } 380 381 hash = fnv_32_buf(cnp->cn_nameptr, cnp->cn_namelen, FNV1_32_INIT); 382 hash = fnv_32_buf(&dvp, sizeof(dvp), hash); 383 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 384 numchecks++; 385 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 386 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 387 break; 388 } 389 390 /* We failed to find an entry */ 391 if (ncp == 0) { 392 if ((cnp->cn_flags & MAKEENTRY) == 0) { 393 nummisszap++; 394 } else { 395 nummiss++; 396 } 397 nchstats.ncs_miss++; 398 CACHE_UNLOCK(); 399 return (0); 400 } 401 402 /* We don't want to have an entry, so dump it */ 403 if ((cnp->cn_flags & MAKEENTRY) == 0) { 404 numposzaps++; 405 nchstats.ncs_badhits++; 406 cache_zap(ncp); 407 CACHE_UNLOCK(); 408 return (0); 409 } 410 411 /* We found a "positive" match, return the vnode */ 412 if (ncp->nc_vp) { 413 numposhits++; 414 nchstats.ncs_goodhits++; 415 *vpp = ncp->nc_vp; 416 CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p", 417 dvp, cnp->cn_nameptr, *vpp, ncp); 418 goto success; 419 } 420 421 /* We found a negative match, and want to create it, so purge */ 422 if (cnp->cn_nameiop == CREATE) { 423 numnegzaps++; 424 nchstats.ncs_badhits++; 425 cache_zap(ncp); 426 CACHE_UNLOCK(); 427 return (0); 428 } 429 430 numneghits++; 431 /* 432 * We found a "negative" match, so we shift it to the end of 433 * the "negative" cache entries queue to satisfy LRU. Also, 434 * check to see if the entry is a whiteout; indicate this to 435 * the componentname, if so. 436 */ 437 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 438 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 439 nchstats.ncs_neghits++; 440 if (ncp->nc_flag & NCF_WHITE) 441 cnp->cn_flags |= ISWHITEOUT; 442 CACHE_UNLOCK(); 443 return (ENOENT); 444 445 success: 446 /* 447 * On success we return a locked and ref'd vnode as per the lookup 448 * protocol. 449 */ 450 if (dvp == *vpp) { /* lookup on "." */ 451 VREF(*vpp); 452 CACHE_UNLOCK(); 453 return (-1); 454 } 455 if (cnp->cn_flags & ISDOTDOT) 456 VOP_UNLOCK(dvp, 0, cnp->cn_thread); 457 VI_LOCK(*vpp); 458 CACHE_UNLOCK(); 459 error = vget(*vpp, cnp->cn_lkflags | LK_INTERLOCK, cnp->cn_thread); 460 if (cnp->cn_flags & ISDOTDOT) 461 vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY, cnp->cn_thread); 462 if (error) { 463 *vpp = NULL; 464 goto retry; 465 } 466 return (-1); 467 } 468 469 /* 470 * Add an entry to the cache. 471 */ 472 void 473 cache_enter(dvp, vp, cnp) 474 struct vnode *dvp; 475 struct vnode *vp; 476 struct componentname *cnp; 477 { 478 struct namecache *ncp, *n2; 479 struct nchashhead *ncpp; 480 u_int32_t hash; 481 int hold; 482 int zap; 483 int len; 484 485 CTR3(KTR_VFS, "cache_enter(%p, %p, %s)", dvp, vp, cnp->cn_nameptr); 486 VNASSERT(vp == NULL || (vp->v_iflag & VI_DOOMED) == 0, vp, 487 ("cahe_enter: Adding a doomed vnode")); 488 489 if (!doingcache) 490 return; 491 492 if (cnp->cn_nameptr[0] == '.') { 493 if (cnp->cn_namelen == 1) { 494 return; 495 } 496 /* 497 * For dotdot lookups only cache the v_dd pointer if the 498 * directory has a link back to its parent via v_cache_dst. 499 * Without this an unlinked directory would keep a soft 500 * reference to its parent which could not be NULLd at 501 * cache_purge() time. 502 */ 503 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 504 CACHE_LOCK(); 505 if (!TAILQ_EMPTY(&dvp->v_cache_dst)) 506 dvp->v_dd = vp; 507 CACHE_UNLOCK(); 508 return; 509 } 510 } 511 512 hold = 0; 513 zap = 0; 514 515 /* 516 * Calculate the hash key and setup as much of the new 517 * namecache entry as possible before acquiring the lock. 518 */ 519 ncp = cache_alloc(cnp->cn_namelen); 520 ncp->nc_vp = vp; 521 ncp->nc_dvp = dvp; 522 len = ncp->nc_nlen = cnp->cn_namelen; 523 hash = fnv_32_buf(cnp->cn_nameptr, len, FNV1_32_INIT); 524 bcopy(cnp->cn_nameptr, ncp->nc_name, len); 525 hash = fnv_32_buf(&dvp, sizeof(dvp), hash); 526 CACHE_LOCK(); 527 528 /* 529 * See if this vnode or negative entry is already in the cache 530 * with this name. This can happen with concurrent lookups of 531 * the same path name. 532 */ 533 ncpp = NCHHASH(hash); 534 LIST_FOREACH(n2, ncpp, nc_hash) { 535 if (n2->nc_dvp == dvp && 536 n2->nc_nlen == cnp->cn_namelen && 537 !bcmp(n2->nc_name, cnp->cn_nameptr, n2->nc_nlen)) { 538 CACHE_UNLOCK(); 539 cache_free(ncp); 540 return; 541 } 542 } 543 544 numcache++; 545 if (!vp) { 546 numneg++; 547 ncp->nc_flag = cnp->cn_flags & ISWHITEOUT ? NCF_WHITE : 0; 548 } else if (vp->v_type == VDIR) { 549 vp->v_dd = dvp; 550 } else { 551 vp->v_dd = NULL; 552 } 553 554 /* 555 * Insert the new namecache entry into the appropriate chain 556 * within the cache entries table. 557 */ 558 LIST_INSERT_HEAD(ncpp, ncp, nc_hash); 559 if (LIST_EMPTY(&dvp->v_cache_src)) { 560 hold = 1; 561 numcachehv++; 562 } 563 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); 564 /* 565 * If the entry is "negative", we place it into the 566 * "negative" cache queue, otherwise, we place it into the 567 * destination vnode's cache entries queue. 568 */ 569 if (vp) { 570 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); 571 } else { 572 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 573 } 574 if (numneg * ncnegfactor > numcache) { 575 ncp = TAILQ_FIRST(&ncneg); 576 zap = 1; 577 } 578 if (hold) 579 vhold(dvp); 580 if (zap) 581 cache_zap(ncp); 582 CACHE_UNLOCK(); 583 } 584 585 /* 586 * Name cache initialization, from vfs_init() when we are booting 587 */ 588 static void 589 nchinit(void *dummy __unused) 590 { 591 592 TAILQ_INIT(&ncneg); 593 594 cache_zone_small = uma_zcreate("S VFS Cache", CACHE_ZONE_SMALL, NULL, 595 NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 596 cache_zone_large = uma_zcreate("L VFS Cache", CACHE_ZONE_LARGE, NULL, 597 NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); 598 599 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash); 600 } 601 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL) 602 603 604 /* 605 * Invalidate all entries to a particular vnode. 606 */ 607 void 608 cache_purge(vp) 609 struct vnode *vp; 610 { 611 612 CTR1(KTR_VFS, "cache_purge(%p)", vp); 613 CACHE_LOCK(); 614 while (!LIST_EMPTY(&vp->v_cache_src)) 615 cache_zap(LIST_FIRST(&vp->v_cache_src)); 616 while (!TAILQ_EMPTY(&vp->v_cache_dst)) 617 cache_zap(TAILQ_FIRST(&vp->v_cache_dst)); 618 vp->v_dd = NULL; 619 CACHE_UNLOCK(); 620 } 621 622 /* 623 * Flush all entries referencing a particular filesystem. 624 * 625 * Since we need to check it anyway, we will flush all the invalid 626 * entries at the same time. 627 */ 628 void 629 cache_purgevfs(mp) 630 struct mount *mp; 631 { 632 struct nchashhead *ncpp; 633 struct namecache *ncp, *nnp; 634 struct nchashhead mplist; 635 636 LIST_INIT(&mplist); 637 ncp = NULL; 638 639 /* Scan hash tables for applicable entries */ 640 CACHE_LOCK(); 641 for (ncpp = &nchashtbl[nchash]; ncpp >= nchashtbl; ncpp--) { 642 for (ncp = LIST_FIRST(ncpp); ncp != 0; ncp = nnp) { 643 nnp = LIST_NEXT(ncp, nc_hash); 644 if (ncp->nc_dvp->v_mount == mp) { 645 LIST_REMOVE(ncp, nc_hash); 646 LIST_INSERT_HEAD(&mplist, ncp, nc_hash); 647 } 648 } 649 } 650 while (!LIST_EMPTY(&mplist)) 651 cache_zap(LIST_FIRST(&mplist)); 652 CACHE_UNLOCK(); 653 } 654 655 /* 656 * Perform canonical checks and cache lookup and pass on to filesystem 657 * through the vop_cachedlookup only if needed. 658 */ 659 660 int 661 vfs_cache_lookup(ap) 662 struct vop_lookup_args /* { 663 struct vnode *a_dvp; 664 struct vnode **a_vpp; 665 struct componentname *a_cnp; 666 } */ *ap; 667 { 668 struct vnode *dvp; 669 int error; 670 struct vnode **vpp = ap->a_vpp; 671 struct componentname *cnp = ap->a_cnp; 672 struct ucred *cred = cnp->cn_cred; 673 int flags = cnp->cn_flags; 674 struct thread *td = cnp->cn_thread; 675 676 *vpp = NULL; 677 dvp = ap->a_dvp; 678 679 if (dvp->v_type != VDIR) 680 return (ENOTDIR); 681 682 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && 683 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 684 return (EROFS); 685 686 error = VOP_ACCESS(dvp, VEXEC, cred, td); 687 if (error) 688 return (error); 689 690 error = cache_lookup(dvp, vpp, cnp); 691 if (error == 0) 692 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); 693 if (error == ENOENT) 694 return (error); 695 return (0); 696 } 697 698 699 #ifndef _SYS_SYSPROTO_H_ 700 struct __getcwd_args { 701 u_char *buf; 702 u_int buflen; 703 }; 704 #endif 705 706 /* 707 * XXX All of these sysctls would probably be more productive dead. 708 */ 709 static int disablecwd; 710 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, 711 "Disable the getcwd syscall"); 712 713 /* Implementation of the getcwd syscall */ 714 int 715 __getcwd(td, uap) 716 struct thread *td; 717 struct __getcwd_args *uap; 718 { 719 720 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen)); 721 } 722 723 int 724 kern___getcwd(struct thread *td, u_char *buf, enum uio_seg bufseg, u_int buflen) 725 { 726 char *bp, *tmpbuf; 727 struct filedesc *fdp; 728 int error; 729 730 if (disablecwd) 731 return (ENODEV); 732 if (buflen < 2) 733 return (EINVAL); 734 if (buflen > MAXPATHLEN) 735 buflen = MAXPATHLEN; 736 737 tmpbuf = malloc(buflen, M_TEMP, M_WAITOK); 738 fdp = td->td_proc->p_fd; 739 mtx_lock(&Giant); 740 FILEDESC_LOCK(fdp); 741 error = vn_fullpath1(td, fdp->fd_cdir, fdp->fd_rdir, tmpbuf, 742 &bp, buflen); 743 FILEDESC_UNLOCK(fdp); 744 mtx_unlock(&Giant); 745 746 if (!error) { 747 if (bufseg == UIO_SYSSPACE) 748 bcopy(bp, buf, strlen(bp) + 1); 749 else 750 error = copyout(bp, buf, strlen(bp) + 1); 751 } 752 free(tmpbuf, M_TEMP); 753 return (error); 754 } 755 756 /* 757 * Thus begins the fullpath magic. 758 */ 759 760 #undef STATNODE 761 #define STATNODE(name) \ 762 static u_int name; \ 763 SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, "") 764 765 static int disablefullpath; 766 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0, 767 "Disable the vn_fullpath function"); 768 769 /* These count for kern___getcwd(), too. */ 770 STATNODE(numfullpathcalls); 771 STATNODE(numfullpathfail1); 772 STATNODE(numfullpathfail2); 773 STATNODE(numfullpathfail4); 774 STATNODE(numfullpathfound); 775 776 /* 777 * Retrieve the full filesystem path that correspond to a vnode from the name 778 * cache (if available) 779 */ 780 int 781 vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf) 782 { 783 char *buf; 784 struct filedesc *fdp; 785 int error; 786 787 if (disablefullpath) 788 return (ENODEV); 789 if (vn == NULL) 790 return (EINVAL); 791 792 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 793 fdp = td->td_proc->p_fd; 794 FILEDESC_LOCK(fdp); 795 error = vn_fullpath1(td, vn, fdp->fd_rdir, buf, retbuf, MAXPATHLEN); 796 FILEDESC_UNLOCK(fdp); 797 798 if (!error) 799 *freebuf = buf; 800 else 801 free(buf, M_TEMP); 802 return (error); 803 } 804 805 /* 806 * The magic behind kern___getcwd() and vn_fullpath(). 807 */ 808 static int 809 vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, 810 char *buf, char **retbuf, u_int buflen) 811 { 812 char *bp; 813 int error, i, slash_prefixed; 814 struct namecache *ncp; 815 816 bp = buf + buflen - 1; 817 *bp = '\0'; 818 error = 0; 819 slash_prefixed = 0; 820 821 CACHE_LOCK(); 822 numfullpathcalls++; 823 if (vp->v_type != VDIR) { 824 ncp = TAILQ_FIRST(&vp->v_cache_dst); 825 if (!ncp) { 826 numfullpathfail2++; 827 CACHE_UNLOCK(); 828 return (ENOENT); 829 } 830 for (i = ncp->nc_nlen - 1; i >= 0 && bp > buf; i--) 831 *--bp = ncp->nc_name[i]; 832 if (bp == buf) { 833 numfullpathfail4++; 834 CACHE_UNLOCK(); 835 return (ENOMEM); 836 } 837 *--bp = '/'; 838 slash_prefixed = 1; 839 vp = ncp->nc_dvp; 840 } 841 while (vp != rdir && vp != rootvnode) { 842 if (vp->v_vflag & VV_ROOT) { 843 if (vp->v_iflag & VI_DOOMED) { /* forced unmount */ 844 error = EBADF; 845 break; 846 } 847 vp = vp->v_mount->mnt_vnodecovered; 848 continue; 849 } 850 if (vp->v_dd == NULL) { 851 numfullpathfail1++; 852 error = ENOTDIR; 853 break; 854 } 855 ncp = TAILQ_FIRST(&vp->v_cache_dst); 856 if (!ncp) { 857 numfullpathfail2++; 858 error = ENOENT; 859 break; 860 } 861 MPASS(ncp->nc_dvp == vp->v_dd); 862 for (i = ncp->nc_nlen - 1; i >= 0 && bp != buf; i--) 863 *--bp = ncp->nc_name[i]; 864 if (bp == buf) { 865 numfullpathfail4++; 866 error = ENOMEM; 867 break; 868 } 869 *--bp = '/'; 870 slash_prefixed = 1; 871 vp = ncp->nc_dvp; 872 } 873 if (error) { 874 CACHE_UNLOCK(); 875 return (error); 876 } 877 if (!slash_prefixed) { 878 if (bp == buf) { 879 numfullpathfail4++; 880 CACHE_UNLOCK(); 881 return (ENOMEM); 882 } else { 883 *--bp = '/'; 884 } 885 } 886 numfullpathfound++; 887 CACHE_UNLOCK(); 888 889 *retbuf = bp; 890 return (0); 891 }
Cache object: 2bf9eb527aa042517aa87e27c67b424f
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]