1 /* 2 * Copyright (c) 2003,2004 The DragonFly Project. All rights reserved. 3 * 4 * This code is derived from software contributed to The DragonFly Project 5 * by Matthew Dillon <dillon@backplane.com> 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 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 15 * the documentation and/or other materials provided with the 16 * distribution. 17 * 3. Neither the name of The DragonFly Project nor the names of its 18 * contributors may be used to endorse or promote products derived 19 * from this software without specific, prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * Copyright (c) 1989, 1993, 1995 35 * The Regents of the University of California. All rights reserved. 36 * 37 * This code is derived from software contributed to Berkeley by 38 * Poul-Henning Kamp of the FreeBSD Project. 39 * 40 * Redistribution and use in source and binary forms, with or without 41 * modification, are permitted provided that the following conditions 42 * are met: 43 * 1. Redistributions of source code must retain the above copyright 44 * notice, this list of conditions and the following disclaimer. 45 * 2. Redistributions in binary form must reproduce the above copyright 46 * notice, this list of conditions and the following disclaimer in the 47 * documentation and/or other materials provided with the distribution. 48 * 3. All advertising materials mentioning features or use of this software 49 * must display the following acknowledgement: 50 * This product includes software developed by the University of 51 * California, Berkeley and its contributors. 52 * 4. Neither the name of the University nor the names of its contributors 53 * may be used to endorse or promote products derived from this software 54 * without specific prior written permission. 55 * 56 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 57 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 58 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 59 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 60 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 61 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 62 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 63 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 64 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 65 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 66 * SUCH DAMAGE. 67 * 68 * @(#)vfs_cache.c 8.5 (Berkeley) 3/22/95 69 * $FreeBSD: src/sys/kern/vfs_cache.c,v 1.42.2.6 2001/10/05 20:07:03 dillon Exp $ 70 * $DragonFly: src/sys/kern/vfs_cache.c,v 1.59 2005/09/17 08:29:42 dillon Exp $ 71 */ 72 73 #include <sys/param.h> 74 #include <sys/systm.h> 75 #include <sys/kernel.h> 76 #include <sys/sysctl.h> 77 #include <sys/mount.h> 78 #include <sys/vnode.h> 79 #include <sys/malloc.h> 80 #include <sys/sysproto.h> 81 #include <sys/proc.h> 82 #include <sys/namei.h> 83 #include <sys/nlookup.h> 84 #include <sys/filedesc.h> 85 #include <sys/fnv_hash.h> 86 #include <sys/globaldata.h> 87 #include <sys/kern_syscall.h> 88 #include <sys/dirent.h> 89 #include <ddb/ddb.h> 90 91 /* 92 * Random lookups in the cache are accomplished with a hash table using 93 * a hash key of (nc_src_vp, name). 94 * 95 * Negative entries may exist and correspond to structures where nc_vp 96 * is NULL. In a negative entry, NCF_WHITEOUT will be set if the entry 97 * corresponds to a whited-out directory entry (verses simply not finding the 98 * entry at all). 99 * 100 * Upon reaching the last segment of a path, if the reference is for DELETE, 101 * or NOCACHE is set (rewrite), and the name is located in the cache, it 102 * will be dropped. 103 */ 104 105 /* 106 * Structures associated with name cacheing. 107 */ 108 #define NCHHASH(hash) (&nchashtbl[(hash) & nchash]) 109 #define MINNEG 1024 110 111 MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); 112 113 static LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */ 114 static struct namecache_list ncneglist; /* instead of vnode */ 115 116 /* 117 * ncvp_debug - debug cache_fromvp(). This is used by the NFS server 118 * to create the namecache infrastructure leading to a dangling vnode. 119 * 120 * 0 Only errors are reported 121 * 1 Successes are reported 122 * 2 Successes + the whole directory scan is reported 123 * 3 Force the directory scan code run as if the parent vnode did not 124 * have a namecache record, even if it does have one. 125 */ 126 static int ncvp_debug; 127 SYSCTL_INT(_debug, OID_AUTO, ncvp_debug, CTLFLAG_RW, &ncvp_debug, 0, ""); 128 129 static u_long nchash; /* size of hash table */ 130 SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, ""); 131 132 static u_long ncnegfactor = 16; /* ratio of negative entries */ 133 SYSCTL_ULONG(_debug, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, ""); 134 135 static int nclockwarn; /* warn on locked entries in ticks */ 136 SYSCTL_INT(_debug, OID_AUTO, nclockwarn, CTLFLAG_RW, &nclockwarn, 0, ""); 137 138 static u_long numneg; /* number of cache entries allocated */ 139 SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, ""); 140 141 static u_long numcache; /* number of cache entries allocated */ 142 SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, ""); 143 144 static u_long numunres; /* number of unresolved entries */ 145 SYSCTL_ULONG(_debug, OID_AUTO, numunres, CTLFLAG_RD, &numunres, 0, ""); 146 147 SYSCTL_INT(_debug, OID_AUTO, vnsize, CTLFLAG_RD, 0, sizeof(struct vnode), ""); 148 SYSCTL_INT(_debug, OID_AUTO, ncsize, CTLFLAG_RD, 0, sizeof(struct namecache), ""); 149 150 static int cache_resolve_mp(struct namecache *ncp); 151 static void cache_rehash(struct namecache *ncp); 152 153 /* 154 * The new name cache statistics 155 */ 156 SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, "Name cache statistics"); 157 #define STATNODE(mode, name, var) \ 158 SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, mode, var, 0, ""); 159 STATNODE(CTLFLAG_RD, numneg, &numneg); 160 STATNODE(CTLFLAG_RD, numcache, &numcache); 161 static u_long numcalls; STATNODE(CTLFLAG_RD, numcalls, &numcalls); 162 static u_long dothits; STATNODE(CTLFLAG_RD, dothits, &dothits); 163 static u_long dotdothits; STATNODE(CTLFLAG_RD, dotdothits, &dotdothits); 164 static u_long numchecks; STATNODE(CTLFLAG_RD, numchecks, &numchecks); 165 static u_long nummiss; STATNODE(CTLFLAG_RD, nummiss, &nummiss); 166 static u_long nummisszap; STATNODE(CTLFLAG_RD, nummisszap, &nummisszap); 167 static u_long numposzaps; STATNODE(CTLFLAG_RD, numposzaps, &numposzaps); 168 static u_long numposhits; STATNODE(CTLFLAG_RD, numposhits, &numposhits); 169 static u_long numnegzaps; STATNODE(CTLFLAG_RD, numnegzaps, &numnegzaps); 170 static u_long numneghits; STATNODE(CTLFLAG_RD, numneghits, &numneghits); 171 172 struct nchstats nchstats[SMP_MAXCPU]; 173 /* 174 * Export VFS cache effectiveness statistics to user-land. 175 * 176 * The statistics are left for aggregation to user-land so 177 * neat things can be achieved, like observing per-CPU cache 178 * distribution. 179 */ 180 static int 181 sysctl_nchstats(SYSCTL_HANDLER_ARGS) 182 { 183 struct globaldata *gd; 184 int i, error; 185 186 error = 0; 187 for (i = 0; i < ncpus; ++i) { 188 gd = globaldata_find(i); 189 if ((error = SYSCTL_OUT(req, (void *)&(*gd->gd_nchstats), 190 sizeof(struct nchstats)))) 191 break; 192 } 193 194 return (error); 195 } 196 SYSCTL_PROC(_vfs_cache, OID_AUTO, nchstats, CTLTYPE_OPAQUE|CTLFLAG_RD, 197 0, 0, sysctl_nchstats, "S,nchstats", "VFS cache effectiveness statistics"); 198 199 static void cache_zap(struct namecache *ncp); 200 201 /* 202 * cache_hold() and cache_drop() prevent the premature deletion of a 203 * namecache entry but do not prevent operations (such as zapping) on 204 * that namecache entry. 205 */ 206 static __inline 207 struct namecache * 208 _cache_hold(struct namecache *ncp) 209 { 210 ++ncp->nc_refs; 211 return(ncp); 212 } 213 214 /* 215 * When dropping an entry, if only one ref remains and the entry has not 216 * been resolved, zap it. Since the one reference is being dropped the 217 * entry had better not be locked. 218 */ 219 static __inline 220 void 221 _cache_drop(struct namecache *ncp) 222 { 223 KKASSERT(ncp->nc_refs > 0); 224 if (ncp->nc_refs == 1 && 225 (ncp->nc_flag & NCF_UNRESOLVED) && 226 TAILQ_EMPTY(&ncp->nc_list) 227 ) { 228 KKASSERT(ncp->nc_exlocks == 0); 229 cache_lock(ncp); 230 cache_zap(ncp); 231 } else { 232 --ncp->nc_refs; 233 } 234 } 235 236 /* 237 * Link a new namecache entry to its parent. Be careful to avoid races 238 * if vhold() blocks in the future. 239 * 240 * If we are creating a child under an oldapi parent we must mark the 241 * child as being an oldapi entry as well. 242 */ 243 static void 244 cache_link_parent(struct namecache *ncp, struct namecache *par) 245 { 246 KKASSERT(ncp->nc_parent == NULL); 247 ncp->nc_parent = par; 248 if (TAILQ_EMPTY(&par->nc_list)) { 249 TAILQ_INSERT_HEAD(&par->nc_list, ncp, nc_entry); 250 /* 251 * Any vp associated with an ncp which has children must 252 * be held to prevent it from being recycled. 253 */ 254 if (par->nc_vp) 255 vhold(par->nc_vp); 256 } else { 257 TAILQ_INSERT_HEAD(&par->nc_list, ncp, nc_entry); 258 } 259 } 260 261 /* 262 * Remove the parent association from a namecache structure. If this is 263 * the last child of the parent the cache_drop(par) will attempt to 264 * recursively zap the parent. 265 */ 266 static void 267 cache_unlink_parent(struct namecache *ncp) 268 { 269 struct namecache *par; 270 271 if ((par = ncp->nc_parent) != NULL) { 272 ncp->nc_parent = NULL; 273 par = cache_hold(par); 274 TAILQ_REMOVE(&par->nc_list, ncp, nc_entry); 275 if (par->nc_vp && TAILQ_EMPTY(&par->nc_list)) 276 vdrop(par->nc_vp); 277 cache_drop(par); 278 } 279 } 280 281 /* 282 * Allocate a new namecache structure. Most of the code does not require 283 * zero-termination of the string but it makes vop_compat_ncreate() easier. 284 */ 285 static struct namecache * 286 cache_alloc(int nlen) 287 { 288 struct namecache *ncp; 289 290 ncp = malloc(sizeof(*ncp), M_VFSCACHE, M_WAITOK|M_ZERO); 291 if (nlen) 292 ncp->nc_name = malloc(nlen + 1, M_VFSCACHE, M_WAITOK); 293 ncp->nc_nlen = nlen; 294 ncp->nc_flag = NCF_UNRESOLVED; 295 ncp->nc_error = ENOTCONN; /* needs to be resolved */ 296 ncp->nc_refs = 1; 297 ncp->nc_fsmid = 1; 298 TAILQ_INIT(&ncp->nc_list); 299 cache_lock(ncp); 300 return(ncp); 301 } 302 303 static void 304 cache_free(struct namecache *ncp) 305 { 306 KKASSERT(ncp->nc_refs == 1 && ncp->nc_exlocks == 1); 307 if (ncp->nc_name) 308 free(ncp->nc_name, M_VFSCACHE); 309 free(ncp, M_VFSCACHE); 310 } 311 312 /* 313 * Ref and deref a namecache structure. 314 */ 315 struct namecache * 316 cache_hold(struct namecache *ncp) 317 { 318 return(_cache_hold(ncp)); 319 } 320 321 void 322 cache_drop(struct namecache *ncp) 323 { 324 _cache_drop(ncp); 325 } 326 327 /* 328 * Namespace locking. The caller must already hold a reference to the 329 * namecache structure in order to lock/unlock it. This function prevents 330 * the namespace from being created or destroyed by accessors other then 331 * the lock holder. 332 * 333 * Note that holding a locked namecache structure prevents other threads 334 * from making namespace changes (e.g. deleting or creating), prevents 335 * vnode association state changes by other threads, and prevents the 336 * namecache entry from being resolved or unresolved by other threads. 337 * 338 * The lock owner has full authority to associate/disassociate vnodes 339 * and resolve/unresolve the locked ncp. 340 * 341 * In particular, if a vnode is associated with a locked cache entry 342 * that vnode will *NOT* be recycled. We accomplish this by vhold()ing the 343 * vnode. XXX we should find a more efficient way to prevent the vnode 344 * from being recycled, but remember that any given vnode may have multiple 345 * namecache associations (think hardlinks). 346 */ 347 void 348 cache_lock(struct namecache *ncp) 349 { 350 thread_t td; 351 int didwarn; 352 353 KKASSERT(ncp->nc_refs != 0); 354 didwarn = 0; 355 td = curthread; 356 357 for (;;) { 358 if (ncp->nc_exlocks == 0) { 359 ncp->nc_exlocks = 1; 360 ncp->nc_locktd = td; 361 /* 362 * The vp associated with a locked ncp must be held 363 * to prevent it from being recycled (which would 364 * cause the ncp to become unresolved). 365 * 366 * XXX loop on race for later MPSAFE work. 367 */ 368 if (ncp->nc_vp) 369 vhold(ncp->nc_vp); 370 break; 371 } 372 if (ncp->nc_locktd == td) { 373 ++ncp->nc_exlocks; 374 break; 375 } 376 ncp->nc_flag |= NCF_LOCKREQ; 377 if (tsleep(ncp, 0, "clock", nclockwarn) == EWOULDBLOCK) { 378 if (didwarn) 379 continue; 380 didwarn = 1; 381 printf("[diagnostic] cache_lock: blocked on %p", ncp); 382 if ((ncp->nc_flag & NCF_MOUNTPT) && ncp->nc_mount) 383 printf(" [MOUNTFROM %s]\n", ncp->nc_mount->mnt_stat.f_mntfromname); 384 else 385 printf(" \"%*.*s\"\n", 386 ncp->nc_nlen, ncp->nc_nlen, 387 ncp->nc_name); 388 } 389 } 390 391 if (didwarn == 1) { 392 printf("[diagnostic] cache_lock: unblocked %*.*s\n", 393 ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name); 394 } 395 } 396 397 int 398 cache_lock_nonblock(struct namecache *ncp) 399 { 400 thread_t td; 401 402 KKASSERT(ncp->nc_refs != 0); 403 td = curthread; 404 if (ncp->nc_exlocks == 0) { 405 ncp->nc_exlocks = 1; 406 ncp->nc_locktd = td; 407 /* 408 * The vp associated with a locked ncp must be held 409 * to prevent it from being recycled (which would 410 * cause the ncp to become unresolved). 411 * 412 * XXX loop on race for later MPSAFE work. 413 */ 414 if (ncp->nc_vp) 415 vhold(ncp->nc_vp); 416 return(0); 417 } else { 418 return(EWOULDBLOCK); 419 } 420 } 421 422 void 423 cache_unlock(struct namecache *ncp) 424 { 425 thread_t td = curthread; 426 427 KKASSERT(ncp->nc_refs > 0); 428 KKASSERT(ncp->nc_exlocks > 0); 429 KKASSERT(ncp->nc_locktd == td); 430 if (--ncp->nc_exlocks == 0) { 431 if (ncp->nc_vp) 432 vdrop(ncp->nc_vp); 433 ncp->nc_locktd = NULL; 434 if (ncp->nc_flag & NCF_LOCKREQ) { 435 ncp->nc_flag &= ~NCF_LOCKREQ; 436 wakeup(ncp); 437 } 438 } 439 } 440 441 /* 442 * ref-and-lock, unlock-and-deref functions. 443 */ 444 struct namecache * 445 cache_get(struct namecache *ncp) 446 { 447 _cache_hold(ncp); 448 cache_lock(ncp); 449 return(ncp); 450 } 451 452 int 453 cache_get_nonblock(struct namecache *ncp) 454 { 455 /* XXX MP */ 456 if (ncp->nc_exlocks == 0 || ncp->nc_locktd == curthread) { 457 _cache_hold(ncp); 458 cache_lock(ncp); 459 return(0); 460 } 461 return(EWOULDBLOCK); 462 } 463 464 void 465 cache_put(struct namecache *ncp) 466 { 467 cache_unlock(ncp); 468 _cache_drop(ncp); 469 } 470 471 /* 472 * Resolve an unresolved ncp by associating a vnode with it. If the 473 * vnode is NULL, a negative cache entry is created. 474 * 475 * The ncp should be locked on entry and will remain locked on return. 476 */ 477 void 478 cache_setvp(struct namecache *ncp, struct vnode *vp) 479 { 480 KKASSERT(ncp->nc_flag & NCF_UNRESOLVED); 481 ncp->nc_vp = vp; 482 if (vp != NULL) { 483 /* 484 * Any vp associated with an ncp which has children must 485 * be held. Any vp associated with a locked ncp must be held. 486 */ 487 if (!TAILQ_EMPTY(&ncp->nc_list)) 488 vhold(vp); 489 TAILQ_INSERT_HEAD(&vp->v_namecache, ncp, nc_vnode); 490 if (ncp->nc_exlocks) 491 vhold(vp); 492 493 /* 494 * Set auxillary flags 495 */ 496 switch(vp->v_type) { 497 case VDIR: 498 ncp->nc_flag |= NCF_ISDIR; 499 break; 500 case VLNK: 501 ncp->nc_flag |= NCF_ISSYMLINK; 502 /* XXX cache the contents of the symlink */ 503 break; 504 default: 505 break; 506 } 507 ++numcache; 508 ncp->nc_error = 0; 509 } else { 510 TAILQ_INSERT_TAIL(&ncneglist, ncp, nc_vnode); 511 ++numneg; 512 ncp->nc_error = ENOENT; 513 } 514 ncp->nc_flag &= ~NCF_UNRESOLVED; 515 } 516 517 void 518 cache_settimeout(struct namecache *ncp, int nticks) 519 { 520 if ((ncp->nc_timeout = ticks + nticks) == 0) 521 ncp->nc_timeout = 1; 522 } 523 524 /* 525 * Disassociate the vnode or negative-cache association and mark a 526 * namecache entry as unresolved again. Note that the ncp is still 527 * left in the hash table and still linked to its parent. 528 * 529 * The ncp should be locked and refd on entry and will remain locked and refd 530 * on return. 531 * 532 * This routine is normally never called on a directory containing children. 533 * However, NFS often does just that in its rename() code as a cop-out to 534 * avoid complex namespace operations. This disconnects a directory vnode 535 * from its namecache and can cause the OLDAPI and NEWAPI to get out of 536 * sync. 537 * 538 * NOTE: NCF_FSMID must be cleared so a refurbishment of the ncp, such as 539 * in a create, properly propogates flag up the chain. 540 */ 541 void 542 cache_setunresolved(struct namecache *ncp) 543 { 544 struct vnode *vp; 545 546 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) { 547 ncp->nc_flag |= NCF_UNRESOLVED; 548 ncp->nc_flag &= ~(NCF_WHITEOUT|NCF_ISDIR|NCF_ISSYMLINK| 549 NCF_FSMID); 550 ncp->nc_timeout = 0; 551 ncp->nc_error = ENOTCONN; 552 ++numunres; 553 if ((vp = ncp->nc_vp) != NULL) { 554 --numcache; 555 ncp->nc_vp = NULL; 556 TAILQ_REMOVE(&vp->v_namecache, ncp, nc_vnode); 557 558 /* 559 * Any vp associated with an ncp with children is 560 * held by that ncp. Any vp associated with a locked 561 * ncp is held by that ncp. These conditions must be 562 * undone when the vp is cleared out from the ncp. 563 */ 564 if (!TAILQ_EMPTY(&ncp->nc_list)) 565 vdrop(vp); 566 if (ncp->nc_exlocks) 567 vdrop(vp); 568 } else { 569 TAILQ_REMOVE(&ncneglist, ncp, nc_vnode); 570 --numneg; 571 } 572 } 573 } 574 575 /* 576 * Invalidate portions of the namecache topology given a starting entry. 577 * The passed ncp is set to an unresolved state and: 578 * 579 * The passed ncp must be locked. 580 * 581 * CINV_DESTROY - Set a flag in the passed ncp entry indicating 582 * that the physical underlying nodes have been 583 * destroyed... as in deleted. For example, when 584 * a directory is removed. This will cause record 585 * lookups on the name to no longer be able to find 586 * the record and tells the resolver to return failure 587 * rather then trying to resolve through the parent. 588 * 589 * The topology itself, including ncp->nc_name, 590 * remains intact. 591 * 592 * This only applies to the passed ncp, if CINV_CHILDREN 593 * is specified the children are not flagged. 594 * 595 * CINV_CHILDREN - Set all children (recursively) to an unresolved 596 * state as well. 597 * 598 * Note that this will also have the side effect of 599 * cleaning out any unreferenced nodes in the topology 600 * from the leaves up as the recursion backs out. 601 * 602 * Note that the topology for any referenced nodes remains intact. 603 * 604 * It is possible for cache_inval() to race a cache_resolve(), meaning that 605 * the namecache entry may not actually be invalidated on return if it was 606 * revalidated while recursing down into its children. This code guarentees 607 * that the node(s) will go through an invalidation cycle, but does not 608 * guarentee that they will remain in an invalidated state. 609 * 610 * Returns non-zero if a revalidation was detected during the invalidation 611 * recursion, zero otherwise. Note that since only the original ncp is 612 * locked the revalidation ultimately can only indicate that the original ncp 613 * *MIGHT* no have been reresolved. 614 */ 615 int 616 cache_inval(struct namecache *ncp, int flags) 617 { 618 struct namecache *kid; 619 struct namecache *nextkid; 620 int rcnt = 0; 621 622 KKASSERT(ncp->nc_exlocks); 623 624 cache_setunresolved(ncp); 625 if (flags & CINV_DESTROY) 626 ncp->nc_flag |= NCF_DESTROYED; 627 628 if ((flags & CINV_CHILDREN) && 629 (kid = TAILQ_FIRST(&ncp->nc_list)) != NULL 630 ) { 631 cache_hold(kid); 632 cache_unlock(ncp); 633 while (kid) { 634 if ((nextkid = TAILQ_NEXT(kid, nc_entry)) != NULL) 635 cache_hold(nextkid); 636 if ((kid->nc_flag & NCF_UNRESOLVED) == 0 || 637 TAILQ_FIRST(&kid->nc_list) 638 ) { 639 cache_lock(kid); 640 rcnt += cache_inval(kid, flags & ~CINV_DESTROY); 641 cache_unlock(kid); 642 } 643 cache_drop(kid); 644 kid = nextkid; 645 } 646 cache_lock(ncp); 647 } 648 649 /* 650 * Someone could have gotten in there while ncp was unlocked, 651 * retry if so. 652 */ 653 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) 654 ++rcnt; 655 return (rcnt); 656 } 657 658 /* 659 * Invalidate a vnode's namecache associations. To avoid races against 660 * the resolver we do not invalidate a node which we previously invalidated 661 * but which was then re-resolved while we were in the invalidation loop. 662 * 663 * Returns non-zero if any namecache entries remain after the invalidation 664 * loop completed. 665 * 666 * NOTE: unlike the namecache topology which guarentees that ncp's will not 667 * be ripped out of the topology while held, the vnode's v_namecache list 668 * has no such restriction. NCP's can be ripped out of the list at virtually 669 * any time if not locked, even if held. 670 */ 671 int 672 cache_inval_vp(struct vnode *vp, int flags, int *retflags) 673 { 674 struct namecache *ncp; 675 struct namecache *next; 676 677 restart: 678 ncp = TAILQ_FIRST(&vp->v_namecache); 679 if (ncp) 680 cache_hold(ncp); 681 while (ncp) { 682 /* loop entered with ncp held */ 683 if ((next = TAILQ_NEXT(ncp, nc_vnode)) != NULL) 684 cache_hold(next); 685 cache_lock(ncp); 686 if (ncp->nc_vp != vp) { 687 printf("Warning: cache_inval_vp: race-A detected on " 688 "%s\n", ncp->nc_name); 689 cache_put(ncp); 690 if (next) 691 cache_drop(next); 692 goto restart; 693 } 694 *retflags |= ncp->nc_flag & NCF_FSMID; 695 cache_inval(ncp, flags); 696 cache_put(ncp); /* also releases reference */ 697 ncp = next; 698 if (ncp && ncp->nc_vp != vp) { 699 printf("Warning: cache_inval_vp: race-B detected on " 700 "%s\n", ncp->nc_name); 701 cache_drop(ncp); 702 goto restart; 703 } 704 } 705 return(TAILQ_FIRST(&vp->v_namecache) != NULL); 706 } 707 708 /* 709 * The source ncp has been renamed to the target ncp. Both fncp and tncp 710 * must be locked. Both will be set to unresolved, any children of tncp 711 * will be disconnected (the prior contents of the target is assumed to be 712 * destroyed by the rename operation, e.g. renaming over an empty directory), 713 * and all children of fncp will be moved to tncp. 714 * 715 * XXX the disconnection could pose a problem, check code paths to make 716 * sure any code that blocks can handle the parent being changed out from 717 * under it. Maybe we should lock the children (watch out for deadlocks) ? 718 * 719 * After we return the caller has the option of calling cache_setvp() if 720 * the vnode of the new target ncp is known. 721 * 722 * Any process CD'd into any of the children will no longer be able to ".." 723 * back out. An rm -rf can cause this situation to occur. 724 */ 725 void 726 cache_rename(struct namecache *fncp, struct namecache *tncp) 727 { 728 struct namecache *scan; 729 int didwarn = 0; 730 731 cache_setunresolved(fncp); 732 cache_setunresolved(tncp); 733 while (cache_inval(tncp, CINV_CHILDREN) != 0) { 734 if (didwarn++ % 10 == 0) { 735 printf("Warning: cache_rename: race during " 736 "rename %s->%s\n", 737 fncp->nc_name, tncp->nc_name); 738 } 739 tsleep(tncp, 0, "mvrace", hz / 10); 740 cache_setunresolved(tncp); 741 } 742 while ((scan = TAILQ_FIRST(&fncp->nc_list)) != NULL) { 743 cache_hold(scan); 744 cache_unlink_parent(scan); 745 cache_link_parent(scan, tncp); 746 if (scan->nc_flag & NCF_HASHED) 747 cache_rehash(scan); 748 cache_drop(scan); 749 } 750 } 751 752 /* 753 * vget the vnode associated with the namecache entry. Resolve the namecache 754 * entry if necessary and deal with namecache/vp races. The passed ncp must 755 * be referenced and may be locked. The ncp's ref/locking state is not 756 * effected by this call. 757 * 758 * lk_type may be LK_SHARED, LK_EXCLUSIVE. A ref'd, possibly locked 759 * (depending on the passed lk_type) will be returned in *vpp with an error 760 * of 0, or NULL will be returned in *vpp with a non-0 error code. The 761 * most typical error is ENOENT, meaning that the ncp represents a negative 762 * cache hit and there is no vnode to retrieve, but other errors can occur 763 * too. 764 * 765 * The main race we have to deal with are namecache zaps. The ncp itself 766 * will not disappear since it is referenced, and it turns out that the 767 * validity of the vp pointer can be checked simply by rechecking the 768 * contents of ncp->nc_vp. 769 */ 770 int 771 cache_vget(struct namecache *ncp, struct ucred *cred, 772 int lk_type, struct vnode **vpp) 773 { 774 struct vnode *vp; 775 int error; 776 777 again: 778 vp = NULL; 779 if (ncp->nc_flag & NCF_UNRESOLVED) { 780 cache_lock(ncp); 781 error = cache_resolve(ncp, cred); 782 cache_unlock(ncp); 783 } else { 784 error = 0; 785 } 786 if (error == 0 && (vp = ncp->nc_vp) != NULL) { 787 error = vget(vp, lk_type, curthread); 788 if (error) { 789 if (vp != ncp->nc_vp) /* handle cache_zap race */ 790 goto again; 791 vp = NULL; 792 } else if (vp != ncp->nc_vp) { /* handle cache_zap race */ 793 vput(vp); 794 goto again; 795 } 796 } 797 if (error == 0 && vp == NULL) 798 error = ENOENT; 799 *vpp = vp; 800 return(error); 801 } 802 803 int 804 cache_vref(struct namecache *ncp, struct ucred *cred, struct vnode **vpp) 805 { 806 struct vnode *vp; 807 int error; 808 809 again: 810 vp = NULL; 811 if (ncp->nc_flag & NCF_UNRESOLVED) { 812 cache_lock(ncp); 813 error = cache_resolve(ncp, cred); 814 cache_unlock(ncp); 815 } else { 816 error = 0; 817 } 818 if (error == 0 && (vp = ncp->nc_vp) != NULL) { 819 vref(vp); 820 if (vp != ncp->nc_vp) { /* handle cache_zap race */ 821 vrele(vp); 822 goto again; 823 } 824 } 825 if (error == 0 && vp == NULL) 826 error = ENOENT; 827 *vpp = vp; 828 return(error); 829 } 830 831 /* 832 * Recursively set the FSMID update flag for namecache nodes leading 833 * to root. This will cause the next getattr or reclaim to increment the 834 * fsmid and mark the inode for lazy updating. 835 * 836 * Stop recursing when we hit a node whos NCF_FSMID flag is already set. 837 * This makes FSMIDs work in an Einsteinian fashion - where the observation 838 * effects the result. In this case a program monitoring a higher level 839 * node will have detected some prior change and started its scan (clearing 840 * NCF_FSMID in higher level nodes), but since it has not yet observed the 841 * node where we find NCF_FSMID still set, we can safely make the related 842 * modification without interfering with the theorized program. 843 * 844 * This also means that FSMIDs cannot represent time-domain quantities 845 * in a hierarchical sense. But the main reason for doing it this way 846 * is to reduce the amount of recursion that occurs in the critical path 847 * when e.g. a program is writing to a file that sits deep in a directory 848 * hierarchy. 849 */ 850 void 851 cache_update_fsmid(struct namecache *ncp) 852 { 853 struct vnode *vp; 854 struct namecache *scan; 855 856 if ((vp = ncp->nc_vp) != NULL) { 857 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) { 858 for (scan = ncp; scan; scan = scan->nc_parent) { 859 if (scan->nc_flag & NCF_FSMID) 860 break; 861 scan->nc_flag |= NCF_FSMID; 862 } 863 } 864 } else { 865 while (ncp && (ncp->nc_flag & NCF_FSMID) == 0) { 866 ncp->nc_flag |= NCF_FSMID; 867 ncp = ncp->nc_parent; 868 } 869 } 870 } 871 872 void 873 cache_update_fsmid_vp(struct vnode *vp) 874 { 875 struct namecache *ncp; 876 struct namecache *scan; 877 878 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) { 879 for (scan = ncp; scan; scan = scan->nc_parent) { 880 if (scan->nc_flag & NCF_FSMID) 881 break; 882 scan->nc_flag |= NCF_FSMID; 883 } 884 } 885 } 886 887 /* 888 * If getattr is called on a vnode (e.g. a stat call), the filesystem 889 * may call this routine to determine if the namecache has the hierarchical 890 * change flag set, requiring the fsmid to be updated. 891 * 892 * Since 0 indicates no support, make sure the filesystem fsmid is at least 893 * 1. 894 */ 895 int 896 cache_check_fsmid_vp(struct vnode *vp, int64_t *fsmid) 897 { 898 struct namecache *ncp; 899 int changed = 0; 900 901 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) { 902 if (ncp->nc_flag & NCF_FSMID) { 903 ncp->nc_flag &= ~NCF_FSMID; 904 changed = 1; 905 } 906 } 907 if (*fsmid == 0) 908 ++*fsmid; 909 if (changed) 910 ++*fsmid; 911 return(changed); 912 } 913 914 /* 915 * Convert a directory vnode to a namecache record without any other 916 * knowledge of the topology. This ONLY works with directory vnodes and 917 * is ONLY used by the NFS server. dvp must be refd but unlocked, and the 918 * returned ncp (if not NULL) will be held and unlocked. 919 * 920 * If 'makeit' is 0 and dvp has no existing namecache record, NULL is returned. 921 * If 'makeit' is 1 we attempt to track-down and create the namecache topology 922 * for dvp. This will fail only if the directory has been deleted out from 923 * under the caller. 924 * 925 * Callers must always check for a NULL return no matter the value of 'makeit'. 926 */ 927 928 static int cache_inefficient_scan(struct namecache *ncp, struct ucred *cred, 929 struct vnode *dvp); 930 931 struct namecache * 932 cache_fromdvp(struct vnode *dvp, struct ucred *cred, int makeit) 933 { 934 struct namecache *ncp; 935 struct vnode *pvp; 936 int error; 937 938 /* 939 * Temporary debugging code to force the directory scanning code 940 * to be exercised. 941 */ 942 ncp = NULL; 943 if (ncvp_debug >= 3 && makeit && TAILQ_FIRST(&dvp->v_namecache)) { 944 ncp = TAILQ_FIRST(&dvp->v_namecache); 945 printf("cache_fromdvp: forcing %s\n", ncp->nc_name); 946 goto force; 947 } 948 949 /* 950 * Loop until resolution, inside code will break out on error. 951 */ 952 while ((ncp = TAILQ_FIRST(&dvp->v_namecache)) == NULL && makeit) { 953 force: 954 /* 955 * If dvp is the root of its filesystem it should already 956 * have a namecache pointer associated with it as a side 957 * effect of the mount, but it may have been disassociated. 958 */ 959 if (dvp->v_flag & VROOT) { 960 ncp = cache_get(dvp->v_mount->mnt_ncp); 961 error = cache_resolve_mp(ncp); 962 cache_put(ncp); 963 if (ncvp_debug) { 964 printf("cache_fromdvp: resolve root of mount %p error %d", 965 dvp->v_mount, error); 966 } 967 if (error) { 968 if (ncvp_debug) 969 printf(" failed\n"); 970 ncp = NULL; 971 break; 972 } 973 if (ncvp_debug) 974 printf(" succeeded\n"); 975 continue; 976 } 977 978 /* 979 * Get the parent directory and resolve its ncp. 980 */ 981 error = vop_nlookupdotdot(*dvp->v_ops, dvp, &pvp, cred); 982 if (error) { 983 printf("lookupdotdot failed %d %p\n", error, pvp); 984 break; 985 } 986 VOP_UNLOCK(pvp, 0, curthread); 987 988 /* 989 * XXX this recursion could run the kernel out of stack, 990 * change to a less efficient algorithm if we get too deep 991 * (use 'makeit' for a depth counter?) 992 */ 993 ncp = cache_fromdvp(pvp, cred, makeit); 994 vrele(pvp); 995 if (ncp == NULL) 996 break; 997 998 /* 999 * Do an inefficient scan of pvp (embodied by ncp) to look 1000 * for dvp. This will create a namecache record for dvp on 1001 * success. We loop up to recheck on success. 1002 * 1003 * ncp and dvp are both held but not locked. 1004 */ 1005 error = cache_inefficient_scan(ncp, cred, dvp); 1006 cache_drop(ncp); 1007 if (error) { 1008 printf("cache_fromdvp: scan %p (%s) failed on dvp=%p\n", 1009 pvp, ncp->nc_name, dvp); 1010 ncp = NULL; 1011 break; 1012 } 1013 if (ncvp_debug) { 1014 printf("cache_fromdvp: scan %p (%s) succeeded\n", 1015 pvp, ncp->nc_name); 1016 } 1017 } 1018 if (ncp) 1019 cache_hold(ncp); 1020 return (ncp); 1021 } 1022 1023 /* 1024 * Do an inefficient scan of the directory represented by ncp looking for 1025 * the directory vnode dvp. ncp must be held but not locked on entry and 1026 * will be held on return. dvp must be refd but not locked on entry and 1027 * will remain refd on return. 1028 * 1029 * Why do this at all? Well, due to its stateless nature the NFS server 1030 * converts file handles directly to vnodes without necessarily going through 1031 * the namecache ops that would otherwise create the namecache topology 1032 * leading to the vnode. We could either (1) Change the namecache algorithms 1033 * to allow disconnect namecache records that are re-merged opportunistically, 1034 * or (2) Make the NFS server backtrack and scan to recover a connected 1035 * namecache topology in order to then be able to issue new API lookups. 1036 * 1037 * It turns out that (1) is a huge mess. It takes a nice clean set of 1038 * namecache algorithms and introduces a lot of complication in every subsystem 1039 * that calls into the namecache to deal with the re-merge case, especially 1040 * since we are using the namecache to placehold negative lookups and the 1041 * vnode might not be immediately assigned. (2) is certainly far less 1042 * efficient then (1), but since we are only talking about directories here 1043 * (which are likely to remain cached), the case does not actually run all 1044 * that often and has the supreme advantage of not polluting the namecache 1045 * algorithms. 1046 */ 1047 static int 1048 cache_inefficient_scan(struct namecache *ncp, struct ucred *cred, 1049 struct vnode *dvp) 1050 { 1051 struct nlcomponent nlc; 1052 struct namecache *rncp; 1053 struct dirent *den; 1054 struct vnode *pvp; 1055 struct vattr vat; 1056 struct iovec iov; 1057 struct uio uio; 1058 int blksize; 1059 int eofflag; 1060 int bytes; 1061 char *rbuf; 1062 int error; 1063 1064 vat.va_blocksize = 0; 1065 if ((error = VOP_GETATTR(dvp, &vat, curthread)) != 0) 1066 return (error); 1067 if ((error = cache_vget(ncp, cred, LK_SHARED, &pvp)) != 0) 1068 return (error); 1069 if (ncvp_debug) 1070 printf("inefficient_scan: directory iosize %ld vattr fileid = %ld\n", vat.va_blocksize, (long)vat.va_fileid); 1071 if ((blksize = vat.va_blocksize) == 0) 1072 blksize = DEV_BSIZE; 1073 rbuf = malloc(blksize, M_TEMP, M_WAITOK); 1074 rncp = NULL; 1075 1076 eofflag = 0; 1077 uio.uio_offset = 0; 1078 again: 1079 iov.iov_base = rbuf; 1080 iov.iov_len = blksize; 1081 uio.uio_iov = &iov; 1082 uio.uio_iovcnt = 1; 1083 uio.uio_resid = blksize; 1084 uio.uio_segflg = UIO_SYSSPACE; 1085 uio.uio_rw = UIO_READ; 1086 uio.uio_td = curthread; 1087 1088 if (ncvp_debug >= 2) 1089 printf("cache_inefficient_scan: readdir @ %08x\n", (int)uio.uio_offset); 1090 error = VOP_READDIR(pvp, &uio, cred, &eofflag, NULL, NULL); 1091 if (error == 0) { 1092 den = (struct dirent *)rbuf; 1093 bytes = blksize - uio.uio_resid; 1094 1095 while (bytes > 0) { 1096 if (ncvp_debug >= 2) { 1097 printf("cache_inefficient_scan: %*.*s\n", 1098 den->d_namlen, den->d_namlen, 1099 den->d_name); 1100 } 1101 if (den->d_type != DT_WHT && 1102 den->d_ino == vat.va_fileid) { 1103 if (ncvp_debug) { 1104 printf("cache_inefficient_scan: " 1105 "MATCHED inode %ld path %s/%*.*s\n", 1106 vat.va_fileid, ncp->nc_name, 1107 den->d_namlen, den->d_namlen, 1108 den->d_name); 1109 } 1110 nlc.nlc_nameptr = den->d_name; 1111 nlc.nlc_namelen = den->d_namlen; 1112 VOP_UNLOCK(pvp, 0, curthread); 1113 rncp = cache_nlookup(ncp, &nlc); 1114 KKASSERT(rncp != NULL); 1115 break; 1116 } 1117 bytes -= _DIRENT_DIRSIZ(den); 1118 den = _DIRENT_NEXT(den); 1119 } 1120 if (rncp == NULL && eofflag == 0 && uio.uio_resid != blksize) 1121 goto again; 1122 } 1123 if (rncp) { 1124 vrele(pvp); 1125 if (rncp->nc_flag & NCF_UNRESOLVED) { 1126 cache_setvp(rncp, dvp); 1127 if (ncvp_debug >= 2) { 1128 printf("cache_inefficient_scan: setvp %s/%s = %p\n", 1129 ncp->nc_name, rncp->nc_name, dvp); 1130 } 1131 } else { 1132 if (ncvp_debug >= 2) { 1133 printf("cache_inefficient_scan: setvp %s/%s already set %p/%p\n", 1134 ncp->nc_name, rncp->nc_name, dvp, 1135 rncp->nc_vp); 1136 } 1137 } 1138 if (rncp->nc_vp == NULL) 1139 error = rncp->nc_error; 1140 cache_put(rncp); 1141 } else { 1142 printf("cache_inefficient_scan: dvp %p NOT FOUND in %s\n", 1143 dvp, ncp->nc_name); 1144 vput(pvp); 1145 error = ENOENT; 1146 } 1147 free(rbuf, M_TEMP); 1148 return (error); 1149 } 1150 1151 /* 1152 * Zap a namecache entry. The ncp is unconditionally set to an unresolved 1153 * state, which disassociates it from its vnode or ncneglist. 1154 * 1155 * Then, if there are no additional references to the ncp and no children, 1156 * the ncp is removed from the topology and destroyed. This function will 1157 * also run through the nc_parent chain and destroy parent ncps if possible. 1158 * As a side benefit, it turns out the only conditions that allow running 1159 * up the chain are also the conditions to ensure no deadlock will occur. 1160 * 1161 * References and/or children may exist if the ncp is in the middle of the 1162 * topology, preventing the ncp from being destroyed. 1163 * 1164 * This function must be called with the ncp held and locked and will unlock 1165 * and drop it during zapping. 1166 */ 1167 static void 1168 cache_zap(struct namecache *ncp) 1169 { 1170 struct namecache *par; 1171 1172 /* 1173 * Disassociate the vnode or negative cache ref and set NCF_UNRESOLVED. 1174 */ 1175 cache_setunresolved(ncp); 1176 1177 /* 1178 * Try to scrap the entry and possibly tail-recurse on its parent. 1179 * We only scrap unref'd (other then our ref) unresolved entries, 1180 * we do not scrap 'live' entries. 1181 */ 1182 while (ncp->nc_flag & NCF_UNRESOLVED) { 1183 /* 1184 * Someone other then us has a ref, stop. 1185 */ 1186 if (ncp->nc_refs > 1) 1187 goto done; 1188 1189 /* 1190 * We have children, stop. 1191 */ 1192 if (!TAILQ_EMPTY(&ncp->nc_list)) 1193 goto done; 1194 1195 /* 1196 * Remove ncp from the topology: hash table and parent linkage. 1197 */ 1198 if (ncp->nc_flag & NCF_HASHED) { 1199 ncp->nc_flag &= ~NCF_HASHED; 1200 LIST_REMOVE(ncp, nc_hash); 1201 } 1202 if ((par = ncp->nc_parent) != NULL) { 1203 par = cache_hold(par); 1204 TAILQ_REMOVE(&par->nc_list, ncp, nc_entry); 1205 ncp->nc_parent = NULL; 1206 if (par->nc_vp && TAILQ_EMPTY(&par->nc_list)) 1207 vdrop(par->nc_vp); 1208 } 1209 1210 /* 1211 * ncp should not have picked up any refs. Physically 1212 * destroy the ncp. 1213 */ 1214 KKASSERT(ncp->nc_refs == 1); 1215 --numunres; 1216 /* cache_unlock(ncp) not required */ 1217 ncp->nc_refs = -1; /* safety */ 1218 if (ncp->nc_name) 1219 free(ncp->nc_name, M_VFSCACHE); 1220 free(ncp, M_VFSCACHE); 1221 1222 /* 1223 * Loop on the parent (it may be NULL). Only bother looping 1224 * if the parent has a single ref (ours), which also means 1225 * we can lock it trivially. 1226 */ 1227 ncp = par; 1228 if (ncp == NULL) 1229 return; 1230 if (ncp->nc_refs != 1) { 1231 cache_drop(ncp); 1232 return; 1233 } 1234 KKASSERT(par->nc_exlocks == 0); 1235 cache_lock(ncp); 1236 } 1237 done: 1238 cache_unlock(ncp); 1239 --ncp->nc_refs; 1240 } 1241 1242 static enum { CHI_LOW, CHI_HIGH } cache_hysteresis_state = CHI_LOW; 1243 1244 static __inline 1245 void 1246 cache_hysteresis(void) 1247 { 1248 /* 1249 * Don't cache too many negative hits. We use hysteresis to reduce 1250 * the impact on the critical path. 1251 */ 1252 switch(cache_hysteresis_state) { 1253 case CHI_LOW: 1254 if (numneg > MINNEG && numneg * ncnegfactor > numcache) { 1255 cache_cleanneg(10); 1256 cache_hysteresis_state = CHI_HIGH; 1257 } 1258 break; 1259 case CHI_HIGH: 1260 if (numneg > MINNEG * 9 / 10 && 1261 numneg * ncnegfactor * 9 / 10 > numcache 1262 ) { 1263 cache_cleanneg(10); 1264 } else { 1265 cache_hysteresis_state = CHI_LOW; 1266 } 1267 break; 1268 } 1269 } 1270 1271 /* 1272 * NEW NAMECACHE LOOKUP API 1273 * 1274 * Lookup an entry in the cache. A locked, referenced, non-NULL 1275 * entry is *always* returned, even if the supplied component is illegal. 1276 * The resulting namecache entry should be returned to the system with 1277 * cache_put() or cache_unlock() + cache_drop(). 1278 * 1279 * namecache locks are recursive but care must be taken to avoid lock order 1280 * reversals. 1281 * 1282 * Nobody else will be able to manipulate the associated namespace (e.g. 1283 * create, delete, rename, rename-target) until the caller unlocks the 1284 * entry. 1285 * 1286 * The returned entry will be in one of three states: positive hit (non-null 1287 * vnode), negative hit (null vnode), or unresolved (NCF_UNRESOLVED is set). 1288 * Unresolved entries must be resolved through the filesystem to associate the 1289 * vnode and/or determine whether a positive or negative hit has occured. 1290 * 1291 * It is not necessary to lock a directory in order to lock namespace under 1292 * that directory. In fact, it is explicitly not allowed to do that. A 1293 * directory is typically only locked when being created, renamed, or 1294 * destroyed. 1295 * 1296 * The directory (par) may be unresolved, in which case any returned child 1297 * will likely also be marked unresolved. Likely but not guarenteed. Since 1298 * the filesystem lookup requires a resolved directory vnode the caller is 1299 * responsible for resolving the namecache chain top-down. This API 1300 * specifically allows whole chains to be created in an unresolved state. 1301 */ 1302 struct namecache * 1303 cache_nlookup(struct namecache *par, struct nlcomponent *nlc) 1304 { 1305 struct namecache *ncp; 1306 struct namecache *new_ncp; 1307 struct nchashhead *nchpp; 1308 u_int32_t hash; 1309 globaldata_t gd; 1310 1311 numcalls++; 1312 gd = mycpu; 1313 1314 /* 1315 * Try to locate an existing entry 1316 */ 1317 hash = fnv_32_buf(nlc->nlc_nameptr, nlc->nlc_namelen, FNV1_32_INIT); 1318 hash = fnv_32_buf(&par, sizeof(par), hash); 1319 new_ncp = NULL; 1320 restart: 1321 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 1322 numchecks++; 1323 1324 /* 1325 * Zap entries that have timed out. 1326 */ 1327 if (ncp->nc_timeout && 1328 (int)(ncp->nc_timeout - ticks) < 0 && 1329 (ncp->nc_flag & NCF_UNRESOLVED) == 0 && 1330 ncp->nc_exlocks == 0 1331 ) { 1332 cache_zap(cache_get(ncp)); 1333 goto restart; 1334 } 1335 1336 /* 1337 * Break out if we find a matching entry. Note that 1338 * UNRESOLVED entries may match, but DESTROYED entries 1339 * do not. 1340 */ 1341 if (ncp->nc_parent == par && 1342 ncp->nc_nlen == nlc->nlc_namelen && 1343 bcmp(ncp->nc_name, nlc->nlc_nameptr, ncp->nc_nlen) == 0 && 1344 (ncp->nc_flag & NCF_DESTROYED) == 0 1345 ) { 1346 if (cache_get_nonblock(ncp) == 0) { 1347 if (new_ncp) 1348 cache_free(new_ncp); 1349 goto found; 1350 } 1351 cache_get(ncp); 1352 cache_put(ncp); 1353 goto restart; 1354 } 1355 } 1356 1357 /* 1358 * We failed to locate an entry, create a new entry and add it to 1359 * the cache. We have to relookup after possibly blocking in 1360 * malloc. 1361 */ 1362 if (new_ncp == NULL) { 1363 new_ncp = cache_alloc(nlc->nlc_namelen); 1364 goto restart; 1365 } 1366 1367 ncp = new_ncp; 1368 1369 /* 1370 * Initialize as a new UNRESOLVED entry, lock (non-blocking), 1371 * and link to the parent. The mount point is usually inherited 1372 * from the parent unless this is a special case such as a mount 1373 * point where nlc_namelen is 0. The caller is responsible for 1374 * setting nc_mount in that case. If nlc_namelen is 0 nc_name will 1375 * be NULL. 1376 */ 1377 if (nlc->nlc_namelen) { 1378 bcopy(nlc->nlc_nameptr, ncp->nc_name, nlc->nlc_namelen); 1379 ncp->nc_name[nlc->nlc_namelen] = 0; 1380 ncp->nc_mount = par->nc_mount; 1381 } 1382 nchpp = NCHHASH(hash); 1383 LIST_INSERT_HEAD(nchpp, ncp, nc_hash); 1384 ncp->nc_flag |= NCF_HASHED; 1385 cache_link_parent(ncp, par); 1386 found: 1387 /* 1388 * stats and namecache size management 1389 */ 1390 if (ncp->nc_flag & NCF_UNRESOLVED) 1391 ++gd->gd_nchstats->ncs_miss; 1392 else if (ncp->nc_vp) 1393 ++gd->gd_nchstats->ncs_goodhits; 1394 else 1395 ++gd->gd_nchstats->ncs_neghits; 1396 cache_hysteresis(); 1397 return(ncp); 1398 } 1399 1400 /* 1401 * Resolve an unresolved namecache entry, generally by looking it up. 1402 * The passed ncp must be locked and refd. 1403 * 1404 * Theoretically since a vnode cannot be recycled while held, and since 1405 * the nc_parent chain holds its vnode as long as children exist, the 1406 * direct parent of the cache entry we are trying to resolve should 1407 * have a valid vnode. If not then generate an error that we can 1408 * determine is related to a resolver bug. 1409 * 1410 * Note that successful resolution does not necessarily return an error 1411 * code of 0. If the ncp resolves to a negative cache hit then ENOENT 1412 * will be returned. 1413 */ 1414 int 1415 cache_resolve(struct namecache *ncp, struct ucred *cred) 1416 { 1417 struct namecache *par; 1418 int error; 1419 1420 restart: 1421 /* 1422 * If the ncp is already resolved we have nothing to do. 1423 */ 1424 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) 1425 return (ncp->nc_error); 1426 1427 /* 1428 * Mount points need special handling because the parent does not 1429 * belong to the same filesystem as the ncp. 1430 */ 1431 if (ncp->nc_flag & NCF_MOUNTPT) 1432 return (cache_resolve_mp(ncp)); 1433 1434 /* 1435 * We expect an unbroken chain of ncps to at least the mount point, 1436 * and even all the way to root (but this code doesn't have to go 1437 * past the mount point). 1438 */ 1439 if (ncp->nc_parent == NULL) { 1440 printf("EXDEV case 1 %p %*.*s\n", ncp, 1441 ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name); 1442 ncp->nc_error = EXDEV; 1443 return(ncp->nc_error); 1444 } 1445 1446 /* 1447 * The vp's of the parent directories in the chain are held via vhold() 1448 * due to the existance of the child, and should not disappear. 1449 * However, there are cases where they can disappear: 1450 * 1451 * - due to filesystem I/O errors. 1452 * - due to NFS being stupid about tracking the namespace and 1453 * destroys the namespace for entire directories quite often. 1454 * - due to forced unmounts. 1455 * - due to an rmdir (parent will be marked DESTROYED) 1456 * 1457 * When this occurs we have to track the chain backwards and resolve 1458 * it, looping until the resolver catches up to the current node. We 1459 * could recurse here but we might run ourselves out of kernel stack 1460 * so we do it in a more painful manner. This situation really should 1461 * not occur all that often, or if it does not have to go back too 1462 * many nodes to resolve the ncp. 1463 */ 1464 while (ncp->nc_parent->nc_vp == NULL) { 1465 /* 1466 * This case can occur if a process is CD'd into a 1467 * directory which is then rmdir'd. If the parent is marked 1468 * destroyed there is no point trying to resolve it. 1469 */ 1470 if (ncp->nc_parent->nc_flag & NCF_DESTROYED) 1471 return(ENOENT); 1472 1473 par = ncp->nc_parent; 1474 while (par->nc_parent && par->nc_parent->nc_vp == NULL) 1475 par = par->nc_parent; 1476 if (par->nc_parent == NULL) { 1477 printf("EXDEV case 2 %*.*s\n", 1478 par->nc_nlen, par->nc_nlen, par->nc_name); 1479 return (EXDEV); 1480 } 1481 printf("[diagnostic] cache_resolve: had to recurse on %*.*s\n", 1482 par->nc_nlen, par->nc_nlen, par->nc_name); 1483 /* 1484 * The parent is not set in stone, ref and lock it to prevent 1485 * it from disappearing. Also note that due to renames it 1486 * is possible for our ncp to move and for par to no longer 1487 * be one of its parents. We resolve it anyway, the loop 1488 * will handle any moves. 1489 */ 1490 cache_get(par); 1491 if (par->nc_flag & NCF_MOUNTPT) { 1492 cache_resolve_mp(par); 1493 } else if (par->nc_parent->nc_vp == NULL) { 1494 printf("[diagnostic] cache_resolve: raced on %*.*s\n", par->nc_nlen, par->nc_nlen, par->nc_name); 1495 cache_put(par); 1496 continue; 1497 } else if (par->nc_flag & NCF_UNRESOLVED) { 1498 par->nc_error = VOP_NRESOLVE(par, cred); 1499 } 1500 if ((error = par->nc_error) != 0) { 1501 if (par->nc_error != EAGAIN) { 1502 printf("EXDEV case 3 %*.*s error %d\n", 1503 par->nc_nlen, par->nc_nlen, par->nc_name, 1504 par->nc_error); 1505 cache_put(par); 1506 return(error); 1507 } 1508 printf("[diagnostic] cache_resolve: EAGAIN par %p %*.*s\n", 1509 par, par->nc_nlen, par->nc_nlen, par->nc_name); 1510 } 1511 cache_put(par); 1512 /* loop */ 1513 } 1514 1515 /* 1516 * Call VOP_NRESOLVE() to get the vp, then scan for any disconnected 1517 * ncp's and reattach them. If this occurs the original ncp is marked 1518 * EAGAIN to force a relookup. 1519 * 1520 * NOTE: in order to call VOP_NRESOLVE(), the parent of the passed 1521 * ncp must already be resolved. 1522 */ 1523 KKASSERT((ncp->nc_flag & NCF_MOUNTPT) == 0); 1524 ncp->nc_error = VOP_NRESOLVE(ncp, cred); 1525 /*vop_nresolve(*ncp->nc_parent->nc_vp->v_ops, ncp, cred);*/ 1526 if (ncp->nc_error == EAGAIN) { 1527 printf("[diagnostic] cache_resolve: EAGAIN ncp %p %*.*s\n", 1528 ncp, ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name); 1529 goto restart; 1530 } 1531 return(ncp->nc_error); 1532 } 1533 1534 /* 1535 * Resolve the ncp associated with a mount point. Such ncp's almost always 1536 * remain resolved and this routine is rarely called. NFS MPs tends to force 1537 * re-resolution more often due to its mac-truck-smash-the-namecache 1538 * method of tracking namespace changes. 1539 * 1540 * The semantics for this call is that the passed ncp must be locked on 1541 * entry and will be locked on return. However, if we actually have to 1542 * resolve the mount point we temporarily unlock the entry in order to 1543 * avoid race-to-root deadlocks due to e.g. dead NFS mounts. Because of 1544 * the unlock we have to recheck the flags after we relock. 1545 */ 1546 static int 1547 cache_resolve_mp(struct namecache *ncp) 1548 { 1549 struct vnode *vp; 1550 struct mount *mp = ncp->nc_mount; 1551 int error; 1552 1553 KKASSERT(mp != NULL); 1554 if (ncp->nc_flag & NCF_UNRESOLVED) { 1555 cache_unlock(ncp); 1556 while (vfs_busy(mp, 0, curthread)) 1557 ; 1558 error = VFS_ROOT(mp, &vp); 1559 cache_lock(ncp); 1560 1561 /* 1562 * recheck the ncp state after relocking. 1563 */ 1564 if (ncp->nc_flag & NCF_UNRESOLVED) { 1565 ncp->nc_error = error; 1566 if (error == 0) { 1567 cache_setvp(ncp, vp); 1568 vput(vp); 1569 } else { 1570 printf("[diagnostic] cache_resolve_mp: failed to resolve mount %p\n", mp); 1571 cache_setvp(ncp, NULL); 1572 } 1573 } else if (error == 0) { 1574 vput(vp); 1575 } 1576 vfs_unbusy(mp, curthread); 1577 } 1578 return(ncp->nc_error); 1579 } 1580 1581 void 1582 cache_cleanneg(int count) 1583 { 1584 struct namecache *ncp; 1585 1586 /* 1587 * Automode from the vnlru proc - clean out 10% of the negative cache 1588 * entries. 1589 */ 1590 if (count == 0) 1591 count = numneg / 10 + 1; 1592 1593 /* 1594 * Attempt to clean out the specified number of negative cache 1595 * entries. 1596 */ 1597 while (count) { 1598 ncp = TAILQ_FIRST(&ncneglist); 1599 if (ncp == NULL) { 1600 KKASSERT(numneg == 0); 1601 break; 1602 } 1603 TAILQ_REMOVE(&ncneglist, ncp, nc_vnode); 1604 TAILQ_INSERT_TAIL(&ncneglist, ncp, nc_vnode); 1605 if (cache_get_nonblock(ncp) == 0) 1606 cache_zap(ncp); 1607 --count; 1608 } 1609 } 1610 1611 /* 1612 * Rehash a ncp. Rehashing is typically required if the name changes (should 1613 * not generally occur) or the parent link changes. This function will 1614 * unhash the ncp if the ncp is no longer hashable. 1615 */ 1616 static void 1617 cache_rehash(struct namecache *ncp) 1618 { 1619 struct nchashhead *nchpp; 1620 u_int32_t hash; 1621 1622 if (ncp->nc_flag & NCF_HASHED) { 1623 ncp->nc_flag &= ~NCF_HASHED; 1624 LIST_REMOVE(ncp, nc_hash); 1625 } 1626 if (ncp->nc_nlen && ncp->nc_parent) { 1627 hash = fnv_32_buf(ncp->nc_name, ncp->nc_nlen, FNV1_32_INIT); 1628 hash = fnv_32_buf(&ncp->nc_parent, 1629 sizeof(ncp->nc_parent), hash); 1630 nchpp = NCHHASH(hash); 1631 LIST_INSERT_HEAD(nchpp, ncp, nc_hash); 1632 ncp->nc_flag |= NCF_HASHED; 1633 } 1634 } 1635 1636 /* 1637 * Name cache initialization, from vfsinit() when we are booting 1638 */ 1639 void 1640 nchinit(void) 1641 { 1642 int i; 1643 globaldata_t gd; 1644 1645 /* initialise per-cpu namecache effectiveness statistics. */ 1646 for (i = 0; i < ncpus; ++i) { 1647 gd = globaldata_find(i); 1648 gd->gd_nchstats = &nchstats[i]; 1649 } 1650 TAILQ_INIT(&ncneglist); 1651 nchashtbl = hashinit(desiredvnodes*2, M_VFSCACHE, &nchash); 1652 nclockwarn = 1 * hz; 1653 } 1654 1655 /* 1656 * Called from start_init() to bootstrap the root filesystem. Returns 1657 * a referenced, unlocked namecache record. 1658 */ 1659 struct namecache * 1660 cache_allocroot(struct mount *mp, struct vnode *vp) 1661 { 1662 struct namecache *ncp = cache_alloc(0); 1663 1664 ncp->nc_flag |= NCF_MOUNTPT | NCF_ROOT; 1665 ncp->nc_mount = mp; 1666 cache_setvp(ncp, vp); 1667 return(ncp); 1668 } 1669 1670 /* 1671 * vfs_cache_setroot() 1672 * 1673 * Create an association between the root of our namecache and 1674 * the root vnode. This routine may be called several times during 1675 * booting. 1676 * 1677 * If the caller intends to save the returned namecache pointer somewhere 1678 * it must cache_hold() it. 1679 */ 1680 void 1681 vfs_cache_setroot(struct vnode *nvp, struct namecache *ncp) 1682 { 1683 struct vnode *ovp; 1684 struct namecache *oncp; 1685 1686 ovp = rootvnode; 1687 oncp = rootncp; 1688 rootvnode = nvp; 1689 rootncp = ncp; 1690 1691 if (ovp) 1692 vrele(ovp); 1693 if (oncp) 1694 cache_drop(oncp); 1695 } 1696 1697 /* 1698 * XXX OLD API COMPAT FUNCTION. This really messes up the new namecache 1699 * topology and is being removed as quickly as possible. The new VOP_N*() 1700 * API calls are required to make specific adjustments using the supplied 1701 * ncp pointers rather then just bogusly purging random vnodes. 1702 * 1703 * Invalidate all namecache entries to a particular vnode as well as 1704 * any direct children of that vnode in the namecache. This is a 1705 * 'catch all' purge used by filesystems that do not know any better. 1706 * 1707 * A new vnode v_id is generated. Note that no vnode will ever have a 1708 * v_id of 0. 1709 * 1710 * Note that the linkage between the vnode and its namecache entries will 1711 * be removed, but the namecache entries themselves might stay put due to 1712 * active references from elsewhere in the system or due to the existance of 1713 * the children. The namecache topology is left intact even if we do not 1714 * know what the vnode association is. Such entries will be marked 1715 * NCF_UNRESOLVED. 1716 * 1717 * XXX: Only time and the size of v_id prevents this from failing: 1718 * XXX: In theory we should hunt down all (struct vnode*, v_id) 1719 * XXX: soft references and nuke them, at least on the global 1720 * XXX: v_id wraparound. The period of resistance can be extended 1721 * XXX: by incrementing each vnodes v_id individually instead of 1722 * XXX: using the global v_id. 1723 * 1724 * Does not support NCP_FSMID accumulation on invalidation (retflags is 1725 * not used). 1726 */ 1727 void 1728 cache_purge(struct vnode *vp) 1729 { 1730 static u_long nextid; 1731 int retflags = 0; 1732 1733 cache_inval_vp(vp, CINV_DESTROY | CINV_CHILDREN, &retflags); 1734 1735 /* 1736 * Calculate a new unique id for ".." handling 1737 */ 1738 do { 1739 nextid++; 1740 } while (nextid == vp->v_id || nextid == 0); 1741 vp->v_id = nextid; 1742 } 1743 1744 /* 1745 * Flush all entries referencing a particular filesystem. 1746 * 1747 * Since we need to check it anyway, we will flush all the invalid 1748 * entries at the same time. 1749 */ 1750 void 1751 cache_purgevfs(struct mount *mp) 1752 { 1753 struct nchashhead *nchpp; 1754 struct namecache *ncp, *nnp; 1755 1756 /* 1757 * Scan hash tables for applicable entries. 1758 */ 1759 for (nchpp = &nchashtbl[nchash]; nchpp >= nchashtbl; nchpp--) { 1760 ncp = LIST_FIRST(nchpp); 1761 if (ncp) 1762 cache_hold(ncp); 1763 while (ncp) { 1764 nnp = LIST_NEXT(ncp, nc_hash); 1765 if (nnp) 1766 cache_hold(nnp); 1767 if (ncp->nc_mount == mp) { 1768 cache_lock(ncp); 1769 cache_zap(ncp); 1770 } else { 1771 cache_drop(ncp); 1772 } 1773 ncp = nnp; 1774 } 1775 } 1776 } 1777 1778 static int disablecwd; 1779 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, ""); 1780 1781 static u_long numcwdcalls; STATNODE(CTLFLAG_RD, numcwdcalls, &numcwdcalls); 1782 static u_long numcwdfail1; STATNODE(CTLFLAG_RD, numcwdfail1, &numcwdfail1); 1783 static u_long numcwdfail2; STATNODE(CTLFLAG_RD, numcwdfail2, &numcwdfail2); 1784 static u_long numcwdfail3; STATNODE(CTLFLAG_RD, numcwdfail3, &numcwdfail3); 1785 static u_long numcwdfail4; STATNODE(CTLFLAG_RD, numcwdfail4, &numcwdfail4); 1786 static u_long numcwdfound; STATNODE(CTLFLAG_RD, numcwdfound, &numcwdfound); 1787 1788 int 1789 __getcwd(struct __getcwd_args *uap) 1790 { 1791 int buflen; 1792 int error; 1793 char *buf; 1794 char *bp; 1795 1796 if (disablecwd) 1797 return (ENODEV); 1798 1799 buflen = uap->buflen; 1800 if (buflen < 2) 1801 return (EINVAL); 1802 if (buflen > MAXPATHLEN) 1803 buflen = MAXPATHLEN; 1804 1805 buf = malloc(buflen, M_TEMP, M_WAITOK); 1806 bp = kern_getcwd(buf, buflen, &error); 1807 if (error == 0) 1808 error = copyout(bp, uap->buf, strlen(bp) + 1); 1809 free(buf, M_TEMP); 1810 return (error); 1811 } 1812 1813 char * 1814 kern_getcwd(char *buf, size_t buflen, int *error) 1815 { 1816 struct proc *p = curproc; 1817 char *bp; 1818 int i, slash_prefixed; 1819 struct filedesc *fdp; 1820 struct namecache *ncp; 1821 1822 numcwdcalls++; 1823 bp = buf; 1824 bp += buflen - 1; 1825 *bp = '\0'; 1826 fdp = p->p_fd; 1827 slash_prefixed = 0; 1828 1829 ncp = fdp->fd_ncdir; 1830 while (ncp && ncp != fdp->fd_nrdir && (ncp->nc_flag & NCF_ROOT) == 0) { 1831 if (ncp->nc_flag & NCF_MOUNTPT) { 1832 if (ncp->nc_mount == NULL) { 1833 *error = EBADF; /* forced unmount? */ 1834 return(NULL); 1835 } 1836 ncp = ncp->nc_parent; 1837 continue; 1838 } 1839 for (i = ncp->nc_nlen - 1; i >= 0; i--) { 1840 if (bp == buf) { 1841 numcwdfail4++; 1842 *error = ENOMEM; 1843 return(NULL); 1844 } 1845 *--bp = ncp->nc_name[i]; 1846 } 1847 if (bp == buf) { 1848 numcwdfail4++; 1849 *error = ENOMEM; 1850 return(NULL); 1851 } 1852 *--bp = '/'; 1853 slash_prefixed = 1; 1854 ncp = ncp->nc_parent; 1855 } 1856 if (ncp == NULL) { 1857 numcwdfail2++; 1858 *error = ENOENT; 1859 return(NULL); 1860 } 1861 if (!slash_prefixed) { 1862 if (bp == buf) { 1863 numcwdfail4++; 1864 *error = ENOMEM; 1865 return(NULL); 1866 } 1867 *--bp = '/'; 1868 } 1869 numcwdfound++; 1870 *error = 0; 1871 return (bp); 1872 } 1873 1874 /* 1875 * Thus begins the fullpath magic. 1876 */ 1877 1878 #undef STATNODE 1879 #define STATNODE(name) \ 1880 static u_int name; \ 1881 SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, "") 1882 1883 static int disablefullpath; 1884 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, 1885 &disablefullpath, 0, ""); 1886 1887 STATNODE(numfullpathcalls); 1888 STATNODE(numfullpathfail1); 1889 STATNODE(numfullpathfail2); 1890 STATNODE(numfullpathfail3); 1891 STATNODE(numfullpathfail4); 1892 STATNODE(numfullpathfound); 1893 1894 int 1895 cache_fullpath(struct proc *p, struct namecache *ncp, char **retbuf, char **freebuf) 1896 { 1897 char *bp, *buf; 1898 int i, slash_prefixed; 1899 struct namecache *fd_nrdir; 1900 1901 numfullpathcalls--; 1902 1903 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 1904 bp = buf + MAXPATHLEN - 1; 1905 *bp = '\0'; 1906 if (p != NULL) 1907 fd_nrdir = p->p_fd->fd_nrdir; 1908 else 1909 fd_nrdir = NULL; 1910 slash_prefixed = 0; 1911 while (ncp && ncp != fd_nrdir && (ncp->nc_flag & NCF_ROOT) == 0) { 1912 if (ncp->nc_flag & NCF_MOUNTPT) { 1913 if (ncp->nc_mount == NULL) { 1914 free(buf, M_TEMP); 1915 return(EBADF); 1916 } 1917 ncp = ncp->nc_parent; 1918 continue; 1919 } 1920 for (i = ncp->nc_nlen - 1; i >= 0; i--) { 1921 if (bp == buf) { 1922 numfullpathfail4++; 1923 free(buf, M_TEMP); 1924 return(ENOMEM); 1925 } 1926 *--bp = ncp->nc_name[i]; 1927 } 1928 if (bp == buf) { 1929 numfullpathfail4++; 1930 free(buf, M_TEMP); 1931 return(ENOMEM); 1932 } 1933 *--bp = '/'; 1934 slash_prefixed = 1; 1935 ncp = ncp->nc_parent; 1936 } 1937 if (ncp == NULL) { 1938 numfullpathfail2++; 1939 free(buf, M_TEMP); 1940 return(ENOENT); 1941 } 1942 if (p != NULL && (ncp->nc_flag & NCF_ROOT) && ncp != fd_nrdir) { 1943 bp = buf + MAXPATHLEN - 1; 1944 *bp = '\0'; 1945 slash_prefixed = 0; 1946 } 1947 if (!slash_prefixed) { 1948 if (bp == buf) { 1949 numfullpathfail4++; 1950 free(buf, M_TEMP); 1951 return(ENOMEM); 1952 } 1953 *--bp = '/'; 1954 } 1955 numfullpathfound++; 1956 *retbuf = bp; 1957 *freebuf = buf; 1958 1959 return(0); 1960 } 1961 1962 int 1963 vn_fullpath(struct proc *p, struct vnode *vn, char **retbuf, char **freebuf) 1964 { 1965 struct namecache *ncp; 1966 1967 numfullpathcalls++; 1968 if (disablefullpath) 1969 return (ENODEV); 1970 1971 if (p == NULL) 1972 return (EINVAL); 1973 1974 /* vn is NULL, client wants us to use p->p_textvp */ 1975 if (vn == NULL) { 1976 if ((vn = p->p_textvp) == NULL) 1977 return (EINVAL); 1978 } 1979 TAILQ_FOREACH(ncp, &vn->v_namecache, nc_vnode) { 1980 if (ncp->nc_nlen) 1981 break; 1982 } 1983 if (ncp == NULL) 1984 return (EINVAL); 1985 1986 numfullpathcalls--; 1987 return(cache_fullpath(p, ncp, retbuf, freebuf)); 1988 } 1989