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 1.76 2006/09/05 00:55:45 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 * This routine may only be called from outside this source module if 207 * nc_refs is already at least 1. 208 * 209 * This is a rare case where callers are allowed to hold a spinlock, 210 * so we can't ourselves. 211 */ 212 static __inline 213 struct namecache * 214 _cache_hold(struct namecache *ncp) 215 { 216 atomic_add_int(&ncp->nc_refs, 1); 217 return(ncp); 218 } 219 220 /* 221 * When dropping an entry, if only one ref remains and the entry has not 222 * been resolved, zap it. Since the one reference is being dropped the 223 * entry had better not be locked. 224 */ 225 static __inline 226 void 227 _cache_drop(struct namecache *ncp) 228 { 229 KKASSERT(ncp->nc_refs > 0); 230 if (ncp->nc_refs == 1 && 231 (ncp->nc_flag & NCF_UNRESOLVED) && 232 TAILQ_EMPTY(&ncp->nc_list) 233 ) { 234 KKASSERT(ncp->nc_exlocks == 0); 235 cache_lock(ncp); 236 cache_zap(ncp); 237 } else { 238 atomic_subtract_int(&ncp->nc_refs, 1); 239 } 240 } 241 242 /* 243 * Link a new namecache entry to its parent. Be careful to avoid races 244 * if vhold() blocks in the future. 245 */ 246 static void 247 cache_link_parent(struct namecache *ncp, struct namecache *par) 248 { 249 KKASSERT(ncp->nc_parent == NULL); 250 ncp->nc_parent = par; 251 if (TAILQ_EMPTY(&par->nc_list)) { 252 TAILQ_INSERT_HEAD(&par->nc_list, ncp, nc_entry); 253 /* 254 * Any vp associated with an ncp which has children must 255 * be held to prevent it from being recycled. 256 */ 257 if (par->nc_vp) 258 vhold(par->nc_vp); 259 } else { 260 TAILQ_INSERT_HEAD(&par->nc_list, ncp, nc_entry); 261 } 262 } 263 264 /* 265 * Remove the parent association from a namecache structure. If this is 266 * the last child of the parent the cache_drop(par) will attempt to 267 * recursively zap the parent. 268 */ 269 static void 270 cache_unlink_parent(struct namecache *ncp) 271 { 272 struct namecache *par; 273 274 if ((par = ncp->nc_parent) != NULL) { 275 ncp->nc_parent = NULL; 276 par = cache_hold(par); 277 TAILQ_REMOVE(&par->nc_list, ncp, nc_entry); 278 if (par->nc_vp && TAILQ_EMPTY(&par->nc_list)) 279 vdrop(par->nc_vp); 280 cache_drop(par); 281 } 282 } 283 284 /* 285 * Allocate a new namecache structure. Most of the code does not require 286 * zero-termination of the string but it makes vop_compat_ncreate() easier. 287 */ 288 static struct namecache * 289 cache_alloc(int nlen) 290 { 291 struct namecache *ncp; 292 293 ncp = kmalloc(sizeof(*ncp), M_VFSCACHE, M_WAITOK|M_ZERO); 294 if (nlen) 295 ncp->nc_name = kmalloc(nlen + 1, M_VFSCACHE, M_WAITOK); 296 ncp->nc_nlen = nlen; 297 ncp->nc_flag = NCF_UNRESOLVED; 298 ncp->nc_error = ENOTCONN; /* needs to be resolved */ 299 ncp->nc_refs = 1; 300 301 /* 302 * Construct a fake FSMID based on the time of day and a 32 bit 303 * roller for uniqueness. This is used to generate a useful 304 * FSMID for filesystems which do not support it. 305 */ 306 ncp->nc_fsmid = cache_getnewfsmid(); 307 TAILQ_INIT(&ncp->nc_list); 308 cache_lock(ncp); 309 return(ncp); 310 } 311 312 static void 313 cache_free(struct namecache *ncp) 314 { 315 KKASSERT(ncp->nc_refs == 1 && ncp->nc_exlocks == 1); 316 if (ncp->nc_name) 317 kfree(ncp->nc_name, M_VFSCACHE); 318 kfree(ncp, M_VFSCACHE); 319 } 320 321 /* 322 * Ref and deref a namecache structure. 323 * 324 * Warning: caller may hold an unrelated read spinlock, which means we can't 325 * use read spinlocks here. 326 */ 327 struct namecache * 328 cache_hold(struct namecache *ncp) 329 { 330 return(_cache_hold(ncp)); 331 } 332 333 void 334 cache_drop(struct namecache *ncp) 335 { 336 _cache_drop(ncp); 337 } 338 339 /* 340 * Namespace locking. The caller must already hold a reference to the 341 * namecache structure in order to lock/unlock it. This function prevents 342 * the namespace from being created or destroyed by accessors other then 343 * the lock holder. 344 * 345 * Note that holding a locked namecache structure prevents other threads 346 * from making namespace changes (e.g. deleting or creating), prevents 347 * vnode association state changes by other threads, and prevents the 348 * namecache entry from being resolved or unresolved by other threads. 349 * 350 * The lock owner has full authority to associate/disassociate vnodes 351 * and resolve/unresolve the locked ncp. 352 * 353 * WARNING! Holding a locked ncp will prevent a vnode from being destroyed 354 * or recycled, but it does NOT help you if the vnode had already initiated 355 * a recyclement. If this is important, use cache_get() rather then 356 * cache_lock() (and deal with the differences in the way the refs counter 357 * is handled). Or, alternatively, make an unconditional call to 358 * cache_validate() or cache_resolve() after cache_lock() returns. 359 */ 360 void 361 cache_lock(struct namecache *ncp) 362 { 363 thread_t td; 364 int didwarn; 365 366 KKASSERT(ncp->nc_refs != 0); 367 didwarn = 0; 368 td = curthread; 369 370 for (;;) { 371 if (ncp->nc_exlocks == 0) { 372 ncp->nc_exlocks = 1; 373 ncp->nc_locktd = td; 374 /* 375 * The vp associated with a locked ncp must be held 376 * to prevent it from being recycled (which would 377 * cause the ncp to become unresolved). 378 * 379 * WARNING! If VRECLAIMED is set the vnode could 380 * already be in the middle of a recycle. Callers 381 * should not assume that nc_vp is usable when 382 * not NULL. cache_vref() or cache_vget() must be 383 * called. 384 * 385 * XXX loop on race for later MPSAFE work. 386 */ 387 if (ncp->nc_vp) 388 vhold(ncp->nc_vp); 389 break; 390 } 391 if (ncp->nc_locktd == td) { 392 ++ncp->nc_exlocks; 393 break; 394 } 395 ncp->nc_flag |= NCF_LOCKREQ; 396 if (tsleep(ncp, 0, "clock", nclockwarn) == EWOULDBLOCK) { 397 if (didwarn) 398 continue; 399 didwarn = 1; 400 printf("[diagnostic] cache_lock: blocked on %p", ncp); 401 if ((ncp->nc_flag & NCF_MOUNTPT) && ncp->nc_mount) 402 printf(" [MOUNTFROM %s]\n", ncp->nc_mount->mnt_stat.f_mntfromname); 403 else 404 printf(" \"%*.*s\"\n", 405 ncp->nc_nlen, ncp->nc_nlen, 406 ncp->nc_name); 407 } 408 } 409 410 if (didwarn == 1) { 411 printf("[diagnostic] cache_lock: unblocked %*.*s\n", 412 ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name); 413 } 414 } 415 416 int 417 cache_lock_nonblock(struct namecache *ncp) 418 { 419 thread_t td; 420 421 KKASSERT(ncp->nc_refs != 0); 422 td = curthread; 423 if (ncp->nc_exlocks == 0) { 424 ncp->nc_exlocks = 1; 425 ncp->nc_locktd = td; 426 /* 427 * The vp associated with a locked ncp must be held 428 * to prevent it from being recycled (which would 429 * cause the ncp to become unresolved). 430 * 431 * WARNING! If VRECLAIMED is set the vnode could 432 * already be in the middle of a recycle. Callers 433 * should not assume that nc_vp is usable when 434 * not NULL. cache_vref() or cache_vget() must be 435 * called. 436 * 437 * XXX loop on race for later MPSAFE work. 438 */ 439 if (ncp->nc_vp) 440 vhold(ncp->nc_vp); 441 return(0); 442 } else { 443 return(EWOULDBLOCK); 444 } 445 } 446 447 void 448 cache_unlock(struct namecache *ncp) 449 { 450 thread_t td = curthread; 451 452 KKASSERT(ncp->nc_refs > 0); 453 KKASSERT(ncp->nc_exlocks > 0); 454 KKASSERT(ncp->nc_locktd == td); 455 if (--ncp->nc_exlocks == 0) { 456 if (ncp->nc_vp) 457 vdrop(ncp->nc_vp); 458 ncp->nc_locktd = NULL; 459 if (ncp->nc_flag & NCF_LOCKREQ) { 460 ncp->nc_flag &= ~NCF_LOCKREQ; 461 wakeup(ncp); 462 } 463 } 464 } 465 466 /* 467 * ref-and-lock, unlock-and-deref functions. 468 * 469 * This function is primarily used by nlookup. Even though cache_lock 470 * holds the vnode, it is possible that the vnode may have already 471 * initiated a recyclement. We want cache_get() to return a definitively 472 * usable vnode or a definitively unresolved ncp. 473 */ 474 struct namecache * 475 cache_get(struct namecache *ncp) 476 { 477 _cache_hold(ncp); 478 cache_lock(ncp); 479 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) 480 cache_setunresolved(ncp); 481 return(ncp); 482 } 483 484 int 485 cache_get_nonblock(struct namecache *ncp) 486 { 487 /* XXX MP */ 488 if (ncp->nc_exlocks == 0 || ncp->nc_locktd == curthread) { 489 _cache_hold(ncp); 490 cache_lock(ncp); 491 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) 492 cache_setunresolved(ncp); 493 return(0); 494 } 495 return(EWOULDBLOCK); 496 } 497 498 void 499 cache_put(struct namecache *ncp) 500 { 501 cache_unlock(ncp); 502 _cache_drop(ncp); 503 } 504 505 /* 506 * Resolve an unresolved ncp by associating a vnode with it. If the 507 * vnode is NULL, a negative cache entry is created. 508 * 509 * The ncp should be locked on entry and will remain locked on return. 510 */ 511 void 512 cache_setvp(struct namecache *ncp, struct vnode *vp) 513 { 514 KKASSERT(ncp->nc_flag & NCF_UNRESOLVED); 515 ncp->nc_vp = vp; 516 if (vp != NULL) { 517 /* 518 * Any vp associated with an ncp which has children must 519 * be held. Any vp associated with a locked ncp must be held. 520 */ 521 if (!TAILQ_EMPTY(&ncp->nc_list)) 522 vhold(vp); 523 TAILQ_INSERT_HEAD(&vp->v_namecache, ncp, nc_vnode); 524 if (ncp->nc_exlocks) 525 vhold(vp); 526 527 /* 528 * Set auxillary flags 529 */ 530 switch(vp->v_type) { 531 case VDIR: 532 ncp->nc_flag |= NCF_ISDIR; 533 break; 534 case VLNK: 535 ncp->nc_flag |= NCF_ISSYMLINK; 536 /* XXX cache the contents of the symlink */ 537 break; 538 default: 539 break; 540 } 541 ++numcache; 542 ncp->nc_error = 0; 543 } else { 544 TAILQ_INSERT_TAIL(&ncneglist, ncp, nc_vnode); 545 ++numneg; 546 ncp->nc_error = ENOENT; 547 } 548 ncp->nc_flag &= ~NCF_UNRESOLVED; 549 } 550 551 void 552 cache_settimeout(struct namecache *ncp, int nticks) 553 { 554 if ((ncp->nc_timeout = ticks + nticks) == 0) 555 ncp->nc_timeout = 1; 556 } 557 558 /* 559 * Disassociate the vnode or negative-cache association and mark a 560 * namecache entry as unresolved again. Note that the ncp is still 561 * left in the hash table and still linked to its parent. 562 * 563 * The ncp should be locked and refd on entry and will remain locked and refd 564 * on return. 565 * 566 * This routine is normally never called on a directory containing children. 567 * However, NFS often does just that in its rename() code as a cop-out to 568 * avoid complex namespace operations. This disconnects a directory vnode 569 * from its namecache and can cause the OLDAPI and NEWAPI to get out of 570 * sync. 571 * 572 * NOTE: NCF_FSMID must be cleared so a refurbishment of the ncp, such as 573 * in a create, properly propogates flag up the chain. 574 */ 575 void 576 cache_setunresolved(struct namecache *ncp) 577 { 578 struct vnode *vp; 579 580 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) { 581 ncp->nc_flag |= NCF_UNRESOLVED; 582 ncp->nc_timeout = 0; 583 ncp->nc_error = ENOTCONN; 584 ++numunres; 585 if ((vp = ncp->nc_vp) != NULL) { 586 --numcache; 587 ncp->nc_vp = NULL; 588 TAILQ_REMOVE(&vp->v_namecache, ncp, nc_vnode); 589 590 /* 591 * Any vp associated with an ncp with children is 592 * held by that ncp. Any vp associated with a locked 593 * ncp is held by that ncp. These conditions must be 594 * undone when the vp is cleared out from the ncp. 595 */ 596 if (ncp->nc_flag & NCF_FSMID) 597 vupdatefsmid(vp); 598 if (!TAILQ_EMPTY(&ncp->nc_list)) 599 vdrop(vp); 600 if (ncp->nc_exlocks) 601 vdrop(vp); 602 } else { 603 TAILQ_REMOVE(&ncneglist, ncp, nc_vnode); 604 --numneg; 605 } 606 ncp->nc_flag &= ~(NCF_WHITEOUT|NCF_ISDIR|NCF_ISSYMLINK| 607 NCF_FSMID); 608 } 609 } 610 611 /* 612 * Invalidate portions of the namecache topology given a starting entry. 613 * The passed ncp is set to an unresolved state and: 614 * 615 * The passed ncp must be locked. 616 * 617 * CINV_DESTROY - Set a flag in the passed ncp entry indicating 618 * that the physical underlying nodes have been 619 * destroyed... as in deleted. For example, when 620 * a directory is removed. This will cause record 621 * lookups on the name to no longer be able to find 622 * the record and tells the resolver to return failure 623 * rather then trying to resolve through the parent. 624 * 625 * The topology itself, including ncp->nc_name, 626 * remains intact. 627 * 628 * This only applies to the passed ncp, if CINV_CHILDREN 629 * is specified the children are not flagged. 630 * 631 * CINV_CHILDREN - Set all children (recursively) to an unresolved 632 * state as well. 633 * 634 * Note that this will also have the side effect of 635 * cleaning out any unreferenced nodes in the topology 636 * from the leaves up as the recursion backs out. 637 * 638 * Note that the topology for any referenced nodes remains intact. 639 * 640 * It is possible for cache_inval() to race a cache_resolve(), meaning that 641 * the namecache entry may not actually be invalidated on return if it was 642 * revalidated while recursing down into its children. This code guarentees 643 * that the node(s) will go through an invalidation cycle, but does not 644 * guarentee that they will remain in an invalidated state. 645 * 646 * Returns non-zero if a revalidation was detected during the invalidation 647 * recursion, zero otherwise. Note that since only the original ncp is 648 * locked the revalidation ultimately can only indicate that the original ncp 649 * *MIGHT* no have been reresolved. 650 */ 651 int 652 cache_inval(struct namecache *ncp, int flags) 653 { 654 struct namecache *kid; 655 struct namecache *nextkid; 656 int rcnt = 0; 657 658 KKASSERT(ncp->nc_exlocks); 659 660 cache_setunresolved(ncp); 661 if (flags & CINV_DESTROY) 662 ncp->nc_flag |= NCF_DESTROYED; 663 664 if ((flags & CINV_CHILDREN) && 665 (kid = TAILQ_FIRST(&ncp->nc_list)) != NULL 666 ) { 667 cache_hold(kid); 668 cache_unlock(ncp); 669 while (kid) { 670 if ((nextkid = TAILQ_NEXT(kid, nc_entry)) != NULL) 671 cache_hold(nextkid); 672 if ((kid->nc_flag & NCF_UNRESOLVED) == 0 || 673 TAILQ_FIRST(&kid->nc_list) 674 ) { 675 cache_lock(kid); 676 rcnt += cache_inval(kid, flags & ~CINV_DESTROY); 677 cache_unlock(kid); 678 } 679 cache_drop(kid); 680 kid = nextkid; 681 } 682 cache_lock(ncp); 683 } 684 685 /* 686 * Someone could have gotten in there while ncp was unlocked, 687 * retry if so. 688 */ 689 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) 690 ++rcnt; 691 return (rcnt); 692 } 693 694 /* 695 * Invalidate a vnode's namecache associations. To avoid races against 696 * the resolver we do not invalidate a node which we previously invalidated 697 * but which was then re-resolved while we were in the invalidation loop. 698 * 699 * Returns non-zero if any namecache entries remain after the invalidation 700 * loop completed. 701 * 702 * NOTE: unlike the namecache topology which guarentees that ncp's will not 703 * be ripped out of the topology while held, the vnode's v_namecache list 704 * has no such restriction. NCP's can be ripped out of the list at virtually 705 * any time if not locked, even if held. 706 */ 707 int 708 cache_inval_vp(struct vnode *vp, int flags) 709 { 710 struct namecache *ncp; 711 struct namecache *next; 712 713 restart: 714 ncp = TAILQ_FIRST(&vp->v_namecache); 715 if (ncp) 716 cache_hold(ncp); 717 while (ncp) { 718 /* loop entered with ncp held */ 719 if ((next = TAILQ_NEXT(ncp, nc_vnode)) != NULL) 720 cache_hold(next); 721 cache_lock(ncp); 722 if (ncp->nc_vp != vp) { 723 printf("Warning: cache_inval_vp: race-A detected on " 724 "%s\n", ncp->nc_name); 725 cache_put(ncp); 726 if (next) 727 cache_drop(next); 728 goto restart; 729 } 730 cache_inval(ncp, flags); 731 cache_put(ncp); /* also releases reference */ 732 ncp = next; 733 if (ncp && ncp->nc_vp != vp) { 734 printf("Warning: cache_inval_vp: race-B detected on " 735 "%s\n", ncp->nc_name); 736 cache_drop(ncp); 737 goto restart; 738 } 739 } 740 return(TAILQ_FIRST(&vp->v_namecache) != NULL); 741 } 742 743 /* 744 * The source ncp has been renamed to the target ncp. Both fncp and tncp 745 * must be locked. Both will be set to unresolved, any children of tncp 746 * will be disconnected (the prior contents of the target is assumed to be 747 * destroyed by the rename operation, e.g. renaming over an empty directory), 748 * and all children of fncp will be moved to tncp. 749 * 750 * XXX the disconnection could pose a problem, check code paths to make 751 * sure any code that blocks can handle the parent being changed out from 752 * under it. Maybe we should lock the children (watch out for deadlocks) ? 753 * 754 * After we return the caller has the option of calling cache_setvp() if 755 * the vnode of the new target ncp is known. 756 * 757 * Any process CD'd into any of the children will no longer be able to ".." 758 * back out. An rm -rf can cause this situation to occur. 759 */ 760 void 761 cache_rename(struct namecache *fncp, struct namecache *tncp) 762 { 763 struct namecache *scan; 764 int didwarn = 0; 765 766 cache_setunresolved(fncp); 767 cache_setunresolved(tncp); 768 while (cache_inval(tncp, CINV_CHILDREN) != 0) { 769 if (didwarn++ % 10 == 0) { 770 printf("Warning: cache_rename: race during " 771 "rename %s->%s\n", 772 fncp->nc_name, tncp->nc_name); 773 } 774 tsleep(tncp, 0, "mvrace", hz / 10); 775 cache_setunresolved(tncp); 776 } 777 while ((scan = TAILQ_FIRST(&fncp->nc_list)) != NULL) { 778 cache_hold(scan); 779 cache_unlink_parent(scan); 780 cache_link_parent(scan, tncp); 781 if (scan->nc_flag & NCF_HASHED) 782 cache_rehash(scan); 783 cache_drop(scan); 784 } 785 } 786 787 /* 788 * vget the vnode associated with the namecache entry. Resolve the namecache 789 * entry if necessary and deal with namecache/vp races. The passed ncp must 790 * be referenced and may be locked. The ncp's ref/locking state is not 791 * effected by this call. 792 * 793 * lk_type may be LK_SHARED, LK_EXCLUSIVE. A ref'd, possibly locked 794 * (depending on the passed lk_type) will be returned in *vpp with an error 795 * of 0, or NULL will be returned in *vpp with a non-0 error code. The 796 * most typical error is ENOENT, meaning that the ncp represents a negative 797 * cache hit and there is no vnode to retrieve, but other errors can occur 798 * too. 799 * 800 * The main race we have to deal with are namecache zaps. The ncp itself 801 * will not disappear since it is referenced, and it turns out that the 802 * validity of the vp pointer can be checked simply by rechecking the 803 * contents of ncp->nc_vp. 804 */ 805 int 806 cache_vget(struct namecache *ncp, struct ucred *cred, 807 int lk_type, struct vnode **vpp) 808 { 809 struct vnode *vp; 810 int error; 811 812 again: 813 vp = NULL; 814 if (ncp->nc_flag & NCF_UNRESOLVED) { 815 cache_lock(ncp); 816 error = cache_resolve(ncp, cred); 817 cache_unlock(ncp); 818 } else { 819 error = 0; 820 } 821 if (error == 0 && (vp = ncp->nc_vp) != NULL) { 822 /* 823 * Accessing the vnode from the namecache is a bit 824 * dangerous. Because there are no refs on the vnode, it 825 * could be in the middle of a reclaim. 826 */ 827 if (vp->v_flag & VRECLAIMED) { 828 printf("Warning: vnode reclaim race detected in cache_vget on %p (%s)\n", vp, ncp->nc_name); 829 cache_lock(ncp); 830 cache_setunresolved(ncp); 831 cache_unlock(ncp); 832 goto again; 833 } 834 error = vget(vp, lk_type); 835 if (error) { 836 if (vp != ncp->nc_vp) 837 goto again; 838 vp = NULL; 839 } else if (vp != ncp->nc_vp) { 840 vput(vp); 841 goto again; 842 } else if (vp->v_flag & VRECLAIMED) { 843 panic("vget succeeded on a VRECLAIMED node! vp %p", vp); 844 } 845 } 846 if (error == 0 && vp == NULL) 847 error = ENOENT; 848 *vpp = vp; 849 return(error); 850 } 851 852 int 853 cache_vref(struct namecache *ncp, struct ucred *cred, struct vnode **vpp) 854 { 855 struct vnode *vp; 856 int error; 857 858 again: 859 vp = NULL; 860 if (ncp->nc_flag & NCF_UNRESOLVED) { 861 cache_lock(ncp); 862 error = cache_resolve(ncp, cred); 863 cache_unlock(ncp); 864 } else { 865 error = 0; 866 } 867 if (error == 0 && (vp = ncp->nc_vp) != NULL) { 868 /* 869 * Since we did not obtain any locks, a cache zap 870 * race can occur here if the vnode is in the middle 871 * of being reclaimed and has not yet been able to 872 * clean out its cache node. If that case occurs, 873 * we must lock and unresolve the cache, then loop 874 * to retry. 875 */ 876 if (vp->v_flag & VRECLAIMED) { 877 printf("Warning: vnode reclaim race detected on cache_vref %p (%s)\n", vp, ncp->nc_name); 878 cache_lock(ncp); 879 cache_setunresolved(ncp); 880 cache_unlock(ncp); 881 goto again; 882 } 883 vref_initial(vp, 1); 884 } 885 if (error == 0 && vp == NULL) 886 error = ENOENT; 887 *vpp = vp; 888 return(error); 889 } 890 891 /* 892 * Recursively set the FSMID update flag for namecache nodes leading 893 * to root. This will cause the next getattr or reclaim to increment the 894 * fsmid and mark the inode for lazy updating. 895 * 896 * Stop recursing when we hit a node whos NCF_FSMID flag is already set. 897 * This makes FSMIDs work in an Einsteinian fashion - where the observation 898 * effects the result. In this case a program monitoring a higher level 899 * node will have detected some prior change and started its scan (clearing 900 * NCF_FSMID in higher level nodes), but since it has not yet observed the 901 * node where we find NCF_FSMID still set, we can safely make the related 902 * modification without interfering with the theorized program. 903 * 904 * This also means that FSMIDs cannot represent time-domain quantities 905 * in a hierarchical sense. But the main reason for doing it this way 906 * is to reduce the amount of recursion that occurs in the critical path 907 * when e.g. a program is writing to a file that sits deep in a directory 908 * hierarchy. 909 */ 910 void 911 cache_update_fsmid(struct namecache *ncp) 912 { 913 struct vnode *vp; 914 struct namecache *scan; 915 916 /* 917 * Warning: even if we get a non-NULL vp it could still be in the 918 * middle of a recyclement. Don't do anything fancy, just set 919 * NCF_FSMID. 920 */ 921 if ((vp = ncp->nc_vp) != NULL) { 922 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) { 923 for (scan = ncp; scan; scan = scan->nc_parent) { 924 if (scan->nc_flag & NCF_FSMID) 925 break; 926 scan->nc_flag |= NCF_FSMID; 927 } 928 } 929 } else { 930 while (ncp && (ncp->nc_flag & NCF_FSMID) == 0) { 931 ncp->nc_flag |= NCF_FSMID; 932 ncp = ncp->nc_parent; 933 } 934 } 935 } 936 937 void 938 cache_update_fsmid_vp(struct vnode *vp) 939 { 940 struct namecache *ncp; 941 struct namecache *scan; 942 943 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) { 944 for (scan = ncp; scan; scan = scan->nc_parent) { 945 if (scan->nc_flag & NCF_FSMID) 946 break; 947 scan->nc_flag |= NCF_FSMID; 948 } 949 } 950 } 951 952 /* 953 * If getattr is called on a vnode (e.g. a stat call), the filesystem 954 * may call this routine to determine if the namecache has the hierarchical 955 * change flag set, requiring the fsmid to be updated. 956 * 957 * Since 0 indicates no support, make sure the filesystem fsmid is at least 958 * 1. 959 */ 960 int 961 cache_check_fsmid_vp(struct vnode *vp, int64_t *fsmid) 962 { 963 struct namecache *ncp; 964 int changed = 0; 965 966 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) { 967 if (ncp->nc_flag & NCF_FSMID) { 968 ncp->nc_flag &= ~NCF_FSMID; 969 changed = 1; 970 } 971 } 972 if (*fsmid == 0) 973 ++*fsmid; 974 if (changed) 975 ++*fsmid; 976 return(changed); 977 } 978 979 /* 980 * Obtain the FSMID for a vnode for filesystems which do not support 981 * a built-in FSMID. 982 */ 983 int64_t 984 cache_sync_fsmid_vp(struct vnode *vp) 985 { 986 struct namecache *ncp; 987 988 if ((ncp = TAILQ_FIRST(&vp->v_namecache)) != NULL) { 989 if (ncp->nc_flag & NCF_FSMID) { 990 ncp->nc_flag &= ~NCF_FSMID; 991 ++ncp->nc_fsmid; 992 } 993 return(ncp->nc_fsmid); 994 } 995 return(VNOVAL); 996 } 997 998 /* 999 * Convert a directory vnode to a namecache record without any other 1000 * knowledge of the topology. This ONLY works with directory vnodes and 1001 * is ONLY used by the NFS server. dvp must be refd but unlocked, and the 1002 * returned ncp (if not NULL) will be held and unlocked. 1003 * 1004 * If 'makeit' is 0 and dvp has no existing namecache record, NULL is returned. 1005 * If 'makeit' is 1 we attempt to track-down and create the namecache topology 1006 * for dvp. This will fail only if the directory has been deleted out from 1007 * under the caller. 1008 * 1009 * Callers must always check for a NULL return no matter the value of 'makeit'. 1010 * 1011 * To avoid underflowing the kernel stack each recursive call increments 1012 * the makeit variable. 1013 */ 1014 1015 static int cache_inefficient_scan(struct namecache *ncp, struct ucred *cred, 1016 struct vnode *dvp); 1017 static int cache_fromdvp_try(struct vnode *dvp, struct ucred *cred, 1018 struct vnode **saved_dvp); 1019 1020 struct namecache * 1021 cache_fromdvp(struct vnode *dvp, struct ucred *cred, int makeit) 1022 { 1023 struct namecache *ncp; 1024 struct vnode *saved_dvp; 1025 struct vnode *pvp; 1026 int error; 1027 1028 ncp = NULL; 1029 saved_dvp = NULL; 1030 1031 /* 1032 * Temporary debugging code to force the directory scanning code 1033 * to be exercised. 1034 */ 1035 if (ncvp_debug >= 3 && makeit && TAILQ_FIRST(&dvp->v_namecache)) { 1036 ncp = TAILQ_FIRST(&dvp->v_namecache); 1037 printf("cache_fromdvp: forcing %s\n", ncp->nc_name); 1038 goto force; 1039 } 1040 1041 /* 1042 * Loop until resolution, inside code will break out on error. 1043 */ 1044 while ((ncp = TAILQ_FIRST(&dvp->v_namecache)) == NULL && makeit) { 1045 force: 1046 /* 1047 * If dvp is the root of its filesystem it should already 1048 * have a namecache pointer associated with it as a side 1049 * effect of the mount, but it may have been disassociated. 1050 */ 1051 if (dvp->v_flag & VROOT) { 1052 ncp = cache_get(dvp->v_mount->mnt_ncp); 1053 error = cache_resolve_mp(ncp); 1054 cache_put(ncp); 1055 if (ncvp_debug) { 1056 printf("cache_fromdvp: resolve root of mount %p error %d", 1057 dvp->v_mount, error); 1058 } 1059 if (error) { 1060 if (ncvp_debug) 1061 printf(" failed\n"); 1062 ncp = NULL; 1063 break; 1064 } 1065 if (ncvp_debug) 1066 printf(" succeeded\n"); 1067 continue; 1068 } 1069 1070 /* 1071 * If we are recursed too deeply resort to an O(n^2) 1072 * algorithm to resolve the namecache topology. The 1073 * resolved pvp is left referenced in saved_dvp to 1074 * prevent the tree from being destroyed while we loop. 1075 */ 1076 if (makeit > 20) { 1077 error = cache_fromdvp_try(dvp, cred, &saved_dvp); 1078 if (error) { 1079 printf("lookupdotdot(longpath) failed %d " 1080 "dvp %p\n", error, dvp); 1081 break; 1082 } 1083 continue; 1084 } 1085 1086 /* 1087 * Get the parent directory and resolve its ncp. 1088 */ 1089 error = vop_nlookupdotdot(*dvp->v_ops, dvp, &pvp, cred); 1090 if (error) { 1091 printf("lookupdotdot failed %d dvp %p\n", error, dvp); 1092 break; 1093 } 1094 vn_unlock(pvp); 1095 1096 /* 1097 * Reuse makeit as a recursion depth counter. 1098 */ 1099 ncp = cache_fromdvp(pvp, cred, makeit + 1); 1100 vrele(pvp); 1101 if (ncp == NULL) 1102 break; 1103 1104 /* 1105 * Do an inefficient scan of pvp (embodied by ncp) to look 1106 * for dvp. This will create a namecache record for dvp on 1107 * success. We loop up to recheck on success. 1108 * 1109 * ncp and dvp are both held but not locked. 1110 */ 1111 error = cache_inefficient_scan(ncp, cred, dvp); 1112 cache_drop(ncp); 1113 if (error) { 1114 printf("cache_fromdvp: scan %p (%s) failed on dvp=%p\n", 1115 pvp, ncp->nc_name, dvp); 1116 ncp = NULL; 1117 break; 1118 } 1119 if (ncvp_debug) { 1120 printf("cache_fromdvp: scan %p (%s) succeeded\n", 1121 pvp, ncp->nc_name); 1122 } 1123 } 1124 if (ncp) 1125 cache_hold(ncp); 1126 if (saved_dvp) 1127 vrele(saved_dvp); 1128 return (ncp); 1129 } 1130 1131 /* 1132 * Go up the chain of parent directories until we find something 1133 * we can resolve into the namecache. This is very inefficient. 1134 */ 1135 static 1136 int 1137 cache_fromdvp_try(struct vnode *dvp, struct ucred *cred, 1138 struct vnode **saved_dvp) 1139 { 1140 struct namecache *ncp; 1141 struct vnode *pvp; 1142 int error; 1143 static time_t last_fromdvp_report; 1144 1145 /* 1146 * Loop getting the parent directory vnode until we get something we 1147 * can resolve in the namecache. 1148 */ 1149 vref(dvp); 1150 for (;;) { 1151 error = vop_nlookupdotdot(*dvp->v_ops, dvp, &pvp, cred); 1152 if (error) { 1153 vrele(dvp); 1154 return (error); 1155 } 1156 vn_unlock(pvp); 1157 if ((ncp = TAILQ_FIRST(&pvp->v_namecache)) != NULL) { 1158 cache_hold(ncp); 1159 vrele(pvp); 1160 break; 1161 } 1162 if (pvp->v_flag & VROOT) { 1163 ncp = cache_get(pvp->v_mount->mnt_ncp); 1164 error = cache_resolve_mp(ncp); 1165 cache_unlock(ncp); 1166 vrele(pvp); 1167 if (error) { 1168 cache_drop(ncp); 1169 vrele(dvp); 1170 return (error); 1171 } 1172 break; 1173 } 1174 vrele(dvp); 1175 dvp = pvp; 1176 } 1177 if (last_fromdvp_report != time_second) { 1178 last_fromdvp_report = time_second; 1179 printf("Warning: extremely inefficient path resolution on %s\n", 1180 ncp->nc_name); 1181 } 1182 error = cache_inefficient_scan(ncp, cred, dvp); 1183 1184 /* 1185 * Hopefully dvp now has a namecache record associated with it. 1186 * Leave it referenced to prevent the kernel from recycling the 1187 * vnode. Otherwise extremely long directory paths could result 1188 * in endless recycling. 1189 */ 1190 if (*saved_dvp) 1191 vrele(*saved_dvp); 1192 *saved_dvp = dvp; 1193 return (error); 1194 } 1195 1196 1197 /* 1198 * Do an inefficient scan of the directory represented by ncp looking for 1199 * the directory vnode dvp. ncp must be held but not locked on entry and 1200 * will be held on return. dvp must be refd but not locked on entry and 1201 * will remain refd on return. 1202 * 1203 * Why do this at all? Well, due to its stateless nature the NFS server 1204 * converts file handles directly to vnodes without necessarily going through 1205 * the namecache ops that would otherwise create the namecache topology 1206 * leading to the vnode. We could either (1) Change the namecache algorithms 1207 * to allow disconnect namecache records that are re-merged opportunistically, 1208 * or (2) Make the NFS server backtrack and scan to recover a connected 1209 * namecache topology in order to then be able to issue new API lookups. 1210 * 1211 * It turns out that (1) is a huge mess. It takes a nice clean set of 1212 * namecache algorithms and introduces a lot of complication in every subsystem 1213 * that calls into the namecache to deal with the re-merge case, especially 1214 * since we are using the namecache to placehold negative lookups and the 1215 * vnode might not be immediately assigned. (2) is certainly far less 1216 * efficient then (1), but since we are only talking about directories here 1217 * (which are likely to remain cached), the case does not actually run all 1218 * that often and has the supreme advantage of not polluting the namecache 1219 * algorithms. 1220 */ 1221 static int 1222 cache_inefficient_scan(struct namecache *ncp, struct ucred *cred, 1223 struct vnode *dvp) 1224 { 1225 struct nlcomponent nlc; 1226 struct namecache *rncp; 1227 struct dirent *den; 1228 struct vnode *pvp; 1229 struct vattr vat; 1230 struct iovec iov; 1231 struct uio uio; 1232 int blksize; 1233 int eofflag; 1234 int bytes; 1235 char *rbuf; 1236 int error; 1237 1238 vat.va_blocksize = 0; 1239 if ((error = VOP_GETATTR(dvp, &vat)) != 0) 1240 return (error); 1241 if ((error = cache_vref(ncp, cred, &pvp)) != 0) 1242 return (error); 1243 if (ncvp_debug) 1244 printf("inefficient_scan: directory iosize %ld vattr fileid = %ld\n", vat.va_blocksize, (long)vat.va_fileid); 1245 if ((blksize = vat.va_blocksize) == 0) 1246 blksize = DEV_BSIZE; 1247 rbuf = kmalloc(blksize, M_TEMP, M_WAITOK); 1248 rncp = NULL; 1249 1250 eofflag = 0; 1251 uio.uio_offset = 0; 1252 again: 1253 iov.iov_base = rbuf; 1254 iov.iov_len = blksize; 1255 uio.uio_iov = &iov; 1256 uio.uio_iovcnt = 1; 1257 uio.uio_resid = blksize; 1258 uio.uio_segflg = UIO_SYSSPACE; 1259 uio.uio_rw = UIO_READ; 1260 uio.uio_td = curthread; 1261 1262 if (ncvp_debug >= 2) 1263 printf("cache_inefficient_scan: readdir @ %08x\n", (int)uio.uio_offset); 1264 error = VOP_READDIR(pvp, &uio, cred, &eofflag, NULL, NULL); 1265 if (error == 0) { 1266 den = (struct dirent *)rbuf; 1267 bytes = blksize - uio.uio_resid; 1268 1269 while (bytes > 0) { 1270 if (ncvp_debug >= 2) { 1271 printf("cache_inefficient_scan: %*.*s\n", 1272 den->d_namlen, den->d_namlen, 1273 den->d_name); 1274 } 1275 if (den->d_type != DT_WHT && 1276 den->d_ino == vat.va_fileid) { 1277 if (ncvp_debug) { 1278 printf("cache_inefficient_scan: " 1279 "MATCHED inode %ld path %s/%*.*s\n", 1280 vat.va_fileid, ncp->nc_name, 1281 den->d_namlen, den->d_namlen, 1282 den->d_name); 1283 } 1284 nlc.nlc_nameptr = den->d_name; 1285 nlc.nlc_namelen = den->d_namlen; 1286 rncp = cache_nlookup(ncp, &nlc); 1287 KKASSERT(rncp != NULL); 1288 break; 1289 } 1290 bytes -= _DIRENT_DIRSIZ(den); 1291 den = _DIRENT_NEXT(den); 1292 } 1293 if (rncp == NULL && eofflag == 0 && uio.uio_resid != blksize) 1294 goto again; 1295 } 1296 vrele(pvp); 1297 if (rncp) { 1298 if (rncp->nc_flag & NCF_UNRESOLVED) { 1299 cache_setvp(rncp, dvp); 1300 if (ncvp_debug >= 2) { 1301 printf("cache_inefficient_scan: setvp %s/%s = %p\n", 1302 ncp->nc_name, rncp->nc_name, dvp); 1303 } 1304 } else { 1305 if (ncvp_debug >= 2) { 1306 printf("cache_inefficient_scan: setvp %s/%s already set %p/%p\n", 1307 ncp->nc_name, rncp->nc_name, dvp, 1308 rncp->nc_vp); 1309 } 1310 } 1311 if (rncp->nc_vp == NULL) 1312 error = rncp->nc_error; 1313 cache_put(rncp); 1314 } else { 1315 printf("cache_inefficient_scan: dvp %p NOT FOUND in %s\n", 1316 dvp, ncp->nc_name); 1317 error = ENOENT; 1318 } 1319 kfree(rbuf, M_TEMP); 1320 return (error); 1321 } 1322 1323 /* 1324 * Zap a namecache entry. The ncp is unconditionally set to an unresolved 1325 * state, which disassociates it from its vnode or ncneglist. 1326 * 1327 * Then, if there are no additional references to the ncp and no children, 1328 * the ncp is removed from the topology and destroyed. This function will 1329 * also run through the nc_parent chain and destroy parent ncps if possible. 1330 * As a side benefit, it turns out the only conditions that allow running 1331 * up the chain are also the conditions to ensure no deadlock will occur. 1332 * 1333 * References and/or children may exist if the ncp is in the middle of the 1334 * topology, preventing the ncp from being destroyed. 1335 * 1336 * This function must be called with the ncp held and locked and will unlock 1337 * and drop it during zapping. 1338 */ 1339 static void 1340 cache_zap(struct namecache *ncp) 1341 { 1342 struct namecache *par; 1343 1344 /* 1345 * Disassociate the vnode or negative cache ref and set NCF_UNRESOLVED. 1346 */ 1347 cache_setunresolved(ncp); 1348 1349 /* 1350 * Try to scrap the entry and possibly tail-recurse on its parent. 1351 * We only scrap unref'd (other then our ref) unresolved entries, 1352 * we do not scrap 'live' entries. 1353 */ 1354 while (ncp->nc_flag & NCF_UNRESOLVED) { 1355 /* 1356 * Someone other then us has a ref, stop. 1357 */ 1358 if (ncp->nc_refs > 1) 1359 goto done; 1360 1361 /* 1362 * We have children, stop. 1363 */ 1364 if (!TAILQ_EMPTY(&ncp->nc_list)) 1365 goto done; 1366 1367 /* 1368 * Remove ncp from the topology: hash table and parent linkage. 1369 */ 1370 if (ncp->nc_flag & NCF_HASHED) { 1371 ncp->nc_flag &= ~NCF_HASHED; 1372 LIST_REMOVE(ncp, nc_hash); 1373 } 1374 if ((par = ncp->nc_parent) != NULL) { 1375 par = cache_hold(par); 1376 TAILQ_REMOVE(&par->nc_list, ncp, nc_entry); 1377 ncp->nc_parent = NULL; 1378 if (par->nc_vp && TAILQ_EMPTY(&par->nc_list)) 1379 vdrop(par->nc_vp); 1380 } 1381 1382 /* 1383 * ncp should not have picked up any refs. Physically 1384 * destroy the ncp. 1385 */ 1386 KKASSERT(ncp->nc_refs == 1); 1387 --numunres; 1388 /* cache_unlock(ncp) not required */ 1389 ncp->nc_refs = -1; /* safety */ 1390 if (ncp->nc_name) 1391 kfree(ncp->nc_name, M_VFSCACHE); 1392 kfree(ncp, M_VFSCACHE); 1393 1394 /* 1395 * Loop on the parent (it may be NULL). Only bother looping 1396 * if the parent has a single ref (ours), which also means 1397 * we can lock it trivially. 1398 */ 1399 ncp = par; 1400 if (ncp == NULL) 1401 return; 1402 if (ncp->nc_refs != 1) { 1403 cache_drop(ncp); 1404 return; 1405 } 1406 KKASSERT(par->nc_exlocks == 0); 1407 cache_lock(ncp); 1408 } 1409 done: 1410 cache_unlock(ncp); 1411 atomic_subtract_int(&ncp->nc_refs, 1); 1412 } 1413 1414 static enum { CHI_LOW, CHI_HIGH } cache_hysteresis_state = CHI_LOW; 1415 1416 static __inline 1417 void 1418 cache_hysteresis(void) 1419 { 1420 /* 1421 * Don't cache too many negative hits. We use hysteresis to reduce 1422 * the impact on the critical path. 1423 */ 1424 switch(cache_hysteresis_state) { 1425 case CHI_LOW: 1426 if (numneg > MINNEG && numneg * ncnegfactor > numcache) { 1427 cache_cleanneg(10); 1428 cache_hysteresis_state = CHI_HIGH; 1429 } 1430 break; 1431 case CHI_HIGH: 1432 if (numneg > MINNEG * 9 / 10 && 1433 numneg * ncnegfactor * 9 / 10 > numcache 1434 ) { 1435 cache_cleanneg(10); 1436 } else { 1437 cache_hysteresis_state = CHI_LOW; 1438 } 1439 break; 1440 } 1441 } 1442 1443 /* 1444 * NEW NAMECACHE LOOKUP API 1445 * 1446 * Lookup an entry in the cache. A locked, referenced, non-NULL 1447 * entry is *always* returned, even if the supplied component is illegal. 1448 * The resulting namecache entry should be returned to the system with 1449 * cache_put() or cache_unlock() + cache_drop(). 1450 * 1451 * namecache locks are recursive but care must be taken to avoid lock order 1452 * reversals. 1453 * 1454 * Nobody else will be able to manipulate the associated namespace (e.g. 1455 * create, delete, rename, rename-target) until the caller unlocks the 1456 * entry. 1457 * 1458 * The returned entry will be in one of three states: positive hit (non-null 1459 * vnode), negative hit (null vnode), or unresolved (NCF_UNRESOLVED is set). 1460 * Unresolved entries must be resolved through the filesystem to associate the 1461 * vnode and/or determine whether a positive or negative hit has occured. 1462 * 1463 * It is not necessary to lock a directory in order to lock namespace under 1464 * that directory. In fact, it is explicitly not allowed to do that. A 1465 * directory is typically only locked when being created, renamed, or 1466 * destroyed. 1467 * 1468 * The directory (par) may be unresolved, in which case any returned child 1469 * will likely also be marked unresolved. Likely but not guarenteed. Since 1470 * the filesystem lookup requires a resolved directory vnode the caller is 1471 * responsible for resolving the namecache chain top-down. This API 1472 * specifically allows whole chains to be created in an unresolved state. 1473 */ 1474 struct namecache * 1475 cache_nlookup(struct namecache *par, struct nlcomponent *nlc) 1476 { 1477 struct namecache *ncp; 1478 struct namecache *new_ncp; 1479 struct nchashhead *nchpp; 1480 u_int32_t hash; 1481 globaldata_t gd; 1482 1483 numcalls++; 1484 gd = mycpu; 1485 1486 /* 1487 * Try to locate an existing entry 1488 */ 1489 hash = fnv_32_buf(nlc->nlc_nameptr, nlc->nlc_namelen, FNV1_32_INIT); 1490 hash = fnv_32_buf(&par, sizeof(par), hash); 1491 new_ncp = NULL; 1492 restart: 1493 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 1494 numchecks++; 1495 1496 /* 1497 * Zap entries that have timed out. 1498 */ 1499 if (ncp->nc_timeout && 1500 (int)(ncp->nc_timeout - ticks) < 0 && 1501 (ncp->nc_flag & NCF_UNRESOLVED) == 0 && 1502 ncp->nc_exlocks == 0 1503 ) { 1504 cache_zap(cache_get(ncp)); 1505 goto restart; 1506 } 1507 1508 /* 1509 * Break out if we find a matching entry. Note that 1510 * UNRESOLVED entries may match, but DESTROYED entries 1511 * do not. 1512 */ 1513 if (ncp->nc_parent == par && 1514 ncp->nc_nlen == nlc->nlc_namelen && 1515 bcmp(ncp->nc_name, nlc->nlc_nameptr, ncp->nc_nlen) == 0 && 1516 (ncp->nc_flag & NCF_DESTROYED) == 0 1517 ) { 1518 if (cache_get_nonblock(ncp) == 0) { 1519 if (new_ncp) 1520 cache_free(new_ncp); 1521 goto found; 1522 } 1523 cache_get(ncp); 1524 cache_put(ncp); 1525 goto restart; 1526 } 1527 } 1528 1529 /* 1530 * We failed to locate an entry, create a new entry and add it to 1531 * the cache. We have to relookup after possibly blocking in 1532 * malloc. 1533 */ 1534 if (new_ncp == NULL) { 1535 new_ncp = cache_alloc(nlc->nlc_namelen); 1536 goto restart; 1537 } 1538 1539 ncp = new_ncp; 1540 1541 /* 1542 * Initialize as a new UNRESOLVED entry, lock (non-blocking), 1543 * and link to the parent. The mount point is usually inherited 1544 * from the parent unless this is a special case such as a mount 1545 * point where nlc_namelen is 0. The caller is responsible for 1546 * setting nc_mount in that case. If nlc_namelen is 0 nc_name will 1547 * be NULL. 1548 */ 1549 if (nlc->nlc_namelen) { 1550 bcopy(nlc->nlc_nameptr, ncp->nc_name, nlc->nlc_namelen); 1551 ncp->nc_name[nlc->nlc_namelen] = 0; 1552 ncp->nc_mount = par->nc_mount; 1553 } 1554 nchpp = NCHHASH(hash); 1555 LIST_INSERT_HEAD(nchpp, ncp, nc_hash); 1556 ncp->nc_flag |= NCF_HASHED; 1557 cache_link_parent(ncp, par); 1558 found: 1559 /* 1560 * stats and namecache size management 1561 */ 1562 if (ncp->nc_flag & NCF_UNRESOLVED) 1563 ++gd->gd_nchstats->ncs_miss; 1564 else if (ncp->nc_vp) 1565 ++gd->gd_nchstats->ncs_goodhits; 1566 else 1567 ++gd->gd_nchstats->ncs_neghits; 1568 cache_hysteresis(); 1569 return(ncp); 1570 } 1571 1572 /* 1573 * Given a locked ncp, validate that the vnode, if present, is actually 1574 * usable. If it is not usable set the ncp to an unresolved state. 1575 */ 1576 void 1577 cache_validate(struct namecache *ncp) 1578 { 1579 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) { 1580 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) 1581 cache_setunresolved(ncp); 1582 } 1583 } 1584 1585 /* 1586 * Resolve an unresolved namecache entry, generally by looking it up. 1587 * The passed ncp must be locked and refd. 1588 * 1589 * Theoretically since a vnode cannot be recycled while held, and since 1590 * the nc_parent chain holds its vnode as long as children exist, the 1591 * direct parent of the cache entry we are trying to resolve should 1592 * have a valid vnode. If not then generate an error that we can 1593 * determine is related to a resolver bug. 1594 * 1595 * However, if a vnode was in the middle of a recyclement when the NCP 1596 * got locked, ncp->nc_vp might point to a vnode that is about to become 1597 * invalid. cache_resolve() handles this case by unresolving the entry 1598 * and then re-resolving it. 1599 * 1600 * Note that successful resolution does not necessarily return an error 1601 * code of 0. If the ncp resolves to a negative cache hit then ENOENT 1602 * will be returned. 1603 */ 1604 int 1605 cache_resolve(struct namecache *ncp, struct ucred *cred) 1606 { 1607 struct namecache *par; 1608 int error; 1609 1610 restart: 1611 /* 1612 * If the ncp is already resolved we have nothing to do. However, 1613 * we do want to guarentee that a usable vnode is returned when 1614 * a vnode is present, so make sure it hasn't been reclaimed. 1615 */ 1616 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) { 1617 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) 1618 cache_setunresolved(ncp); 1619 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) 1620 return (ncp->nc_error); 1621 } 1622 1623 /* 1624 * Mount points need special handling because the parent does not 1625 * belong to the same filesystem as the ncp. 1626 */ 1627 if (ncp->nc_flag & NCF_MOUNTPT) 1628 return (cache_resolve_mp(ncp)); 1629 1630 /* 1631 * We expect an unbroken chain of ncps to at least the mount point, 1632 * and even all the way to root (but this code doesn't have to go 1633 * past the mount point). 1634 */ 1635 if (ncp->nc_parent == NULL) { 1636 printf("EXDEV case 1 %p %*.*s\n", ncp, 1637 ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name); 1638 ncp->nc_error = EXDEV; 1639 return(ncp->nc_error); 1640 } 1641 1642 /* 1643 * The vp's of the parent directories in the chain are held via vhold() 1644 * due to the existance of the child, and should not disappear. 1645 * However, there are cases where they can disappear: 1646 * 1647 * - due to filesystem I/O errors. 1648 * - due to NFS being stupid about tracking the namespace and 1649 * destroys the namespace for entire directories quite often. 1650 * - due to forced unmounts. 1651 * - due to an rmdir (parent will be marked DESTROYED) 1652 * 1653 * When this occurs we have to track the chain backwards and resolve 1654 * it, looping until the resolver catches up to the current node. We 1655 * could recurse here but we might run ourselves out of kernel stack 1656 * so we do it in a more painful manner. This situation really should 1657 * not occur all that often, or if it does not have to go back too 1658 * many nodes to resolve the ncp. 1659 */ 1660 while (ncp->nc_parent->nc_vp == NULL) { 1661 /* 1662 * This case can occur if a process is CD'd into a 1663 * directory which is then rmdir'd. If the parent is marked 1664 * destroyed there is no point trying to resolve it. 1665 */ 1666 if (ncp->nc_parent->nc_flag & NCF_DESTROYED) 1667 return(ENOENT); 1668 1669 par = ncp->nc_parent; 1670 while (par->nc_parent && par->nc_parent->nc_vp == NULL) 1671 par = par->nc_parent; 1672 if (par->nc_parent == NULL) { 1673 printf("EXDEV case 2 %*.*s\n", 1674 par->nc_nlen, par->nc_nlen, par->nc_name); 1675 return (EXDEV); 1676 } 1677 printf("[diagnostic] cache_resolve: had to recurse on %*.*s\n", 1678 par->nc_nlen, par->nc_nlen, par->nc_name); 1679 /* 1680 * The parent is not set in stone, ref and lock it to prevent 1681 * it from disappearing. Also note that due to renames it 1682 * is possible for our ncp to move and for par to no longer 1683 * be one of its parents. We resolve it anyway, the loop 1684 * will handle any moves. 1685 */ 1686 cache_get(par); 1687 if (par->nc_flag & NCF_MOUNTPT) { 1688 cache_resolve_mp(par); 1689 } else if (par->nc_parent->nc_vp == NULL) { 1690 printf("[diagnostic] cache_resolve: raced on %*.*s\n", par->nc_nlen, par->nc_nlen, par->nc_name); 1691 cache_put(par); 1692 continue; 1693 } else if (par->nc_flag & NCF_UNRESOLVED) { 1694 par->nc_error = VOP_NRESOLVE(par, cred); 1695 } 1696 if ((error = par->nc_error) != 0) { 1697 if (par->nc_error != EAGAIN) { 1698 printf("EXDEV case 3 %*.*s error %d\n", 1699 par->nc_nlen, par->nc_nlen, par->nc_name, 1700 par->nc_error); 1701 cache_put(par); 1702 return(error); 1703 } 1704 printf("[diagnostic] cache_resolve: EAGAIN par %p %*.*s\n", 1705 par, par->nc_nlen, par->nc_nlen, par->nc_name); 1706 } 1707 cache_put(par); 1708 /* loop */ 1709 } 1710 1711 /* 1712 * Call VOP_NRESOLVE() to get the vp, then scan for any disconnected 1713 * ncp's and reattach them. If this occurs the original ncp is marked 1714 * EAGAIN to force a relookup. 1715 * 1716 * NOTE: in order to call VOP_NRESOLVE(), the parent of the passed 1717 * ncp must already be resolved. 1718 */ 1719 KKASSERT((ncp->nc_flag & NCF_MOUNTPT) == 0); 1720 ncp->nc_error = VOP_NRESOLVE(ncp, cred); 1721 /*vop_nresolve(*ncp->nc_parent->nc_vp->v_ops, ncp, cred);*/ 1722 if (ncp->nc_error == EAGAIN) { 1723 printf("[diagnostic] cache_resolve: EAGAIN ncp %p %*.*s\n", 1724 ncp, ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name); 1725 goto restart; 1726 } 1727 return(ncp->nc_error); 1728 } 1729 1730 /* 1731 * Resolve the ncp associated with a mount point. Such ncp's almost always 1732 * remain resolved and this routine is rarely called. NFS MPs tends to force 1733 * re-resolution more often due to its mac-truck-smash-the-namecache 1734 * method of tracking namespace changes. 1735 * 1736 * The semantics for this call is that the passed ncp must be locked on 1737 * entry and will be locked on return. However, if we actually have to 1738 * resolve the mount point we temporarily unlock the entry in order to 1739 * avoid race-to-root deadlocks due to e.g. dead NFS mounts. Because of 1740 * the unlock we have to recheck the flags after we relock. 1741 */ 1742 static int 1743 cache_resolve_mp(struct namecache *ncp) 1744 { 1745 struct vnode *vp; 1746 struct mount *mp = ncp->nc_mount; 1747 int error; 1748 1749 KKASSERT(mp != NULL); 1750 1751 /* 1752 * If the ncp is already resolved we have nothing to do. However, 1753 * we do want to guarentee that a usable vnode is returned when 1754 * a vnode is present, so make sure it hasn't been reclaimed. 1755 */ 1756 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) { 1757 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) 1758 cache_setunresolved(ncp); 1759 } 1760 1761 if (ncp->nc_flag & NCF_UNRESOLVED) { 1762 cache_unlock(ncp); 1763 while (vfs_busy(mp, 0)) 1764 ; 1765 error = VFS_ROOT(mp, &vp); 1766 cache_lock(ncp); 1767 1768 /* 1769 * recheck the ncp state after relocking. 1770 */ 1771 if (ncp->nc_flag & NCF_UNRESOLVED) { 1772 ncp->nc_error = error; 1773 if (error == 0) { 1774 cache_setvp(ncp, vp); 1775 vput(vp); 1776 } else { 1777 printf("[diagnostic] cache_resolve_mp: failed to resolve mount %p\n", mp); 1778 cache_setvp(ncp, NULL); 1779 } 1780 } else if (error == 0) { 1781 vput(vp); 1782 } 1783 vfs_unbusy(mp); 1784 } 1785 return(ncp->nc_error); 1786 } 1787 1788 void 1789 cache_cleanneg(int count) 1790 { 1791 struct namecache *ncp; 1792 1793 /* 1794 * Automode from the vnlru proc - clean out 10% of the negative cache 1795 * entries. 1796 */ 1797 if (count == 0) 1798 count = numneg / 10 + 1; 1799 1800 /* 1801 * Attempt to clean out the specified number of negative cache 1802 * entries. 1803 */ 1804 while (count) { 1805 ncp = TAILQ_FIRST(&ncneglist); 1806 if (ncp == NULL) { 1807 KKASSERT(numneg == 0); 1808 break; 1809 } 1810 TAILQ_REMOVE(&ncneglist, ncp, nc_vnode); 1811 TAILQ_INSERT_TAIL(&ncneglist, ncp, nc_vnode); 1812 if (cache_get_nonblock(ncp) == 0) 1813 cache_zap(ncp); 1814 --count; 1815 } 1816 } 1817 1818 /* 1819 * Rehash a ncp. Rehashing is typically required if the name changes (should 1820 * not generally occur) or the parent link changes. This function will 1821 * unhash the ncp if the ncp is no longer hashable. 1822 */ 1823 static void 1824 cache_rehash(struct namecache *ncp) 1825 { 1826 struct nchashhead *nchpp; 1827 u_int32_t hash; 1828 1829 if (ncp->nc_flag & NCF_HASHED) { 1830 ncp->nc_flag &= ~NCF_HASHED; 1831 LIST_REMOVE(ncp, nc_hash); 1832 } 1833 if (ncp->nc_nlen && ncp->nc_parent) { 1834 hash = fnv_32_buf(ncp->nc_name, ncp->nc_nlen, FNV1_32_INIT); 1835 hash = fnv_32_buf(&ncp->nc_parent, 1836 sizeof(ncp->nc_parent), hash); 1837 nchpp = NCHHASH(hash); 1838 LIST_INSERT_HEAD(nchpp, ncp, nc_hash); 1839 ncp->nc_flag |= NCF_HASHED; 1840 } 1841 } 1842 1843 /* 1844 * Name cache initialization, from vfsinit() when we are booting 1845 */ 1846 void 1847 nchinit(void) 1848 { 1849 int i; 1850 globaldata_t gd; 1851 1852 /* initialise per-cpu namecache effectiveness statistics. */ 1853 for (i = 0; i < ncpus; ++i) { 1854 gd = globaldata_find(i); 1855 gd->gd_nchstats = &nchstats[i]; 1856 } 1857 TAILQ_INIT(&ncneglist); 1858 nchashtbl = hashinit(desiredvnodes*2, M_VFSCACHE, &nchash); 1859 nclockwarn = 1 * hz; 1860 } 1861 1862 /* 1863 * Called from start_init() to bootstrap the root filesystem. Returns 1864 * a referenced, unlocked namecache record. 1865 */ 1866 struct namecache * 1867 cache_allocroot(struct mount *mp, struct vnode *vp) 1868 { 1869 struct namecache *ncp = cache_alloc(0); 1870 1871 ncp->nc_flag |= NCF_MOUNTPT | NCF_ROOT; 1872 ncp->nc_mount = mp; 1873 cache_setvp(ncp, vp); 1874 return(ncp); 1875 } 1876 1877 /* 1878 * vfs_cache_setroot() 1879 * 1880 * Create an association between the root of our namecache and 1881 * the root vnode. This routine may be called several times during 1882 * booting. 1883 * 1884 * If the caller intends to save the returned namecache pointer somewhere 1885 * it must cache_hold() it. 1886 */ 1887 void 1888 vfs_cache_setroot(struct vnode *nvp, struct namecache *ncp) 1889 { 1890 struct vnode *ovp; 1891 struct namecache *oncp; 1892 1893 ovp = rootvnode; 1894 oncp = rootncp; 1895 rootvnode = nvp; 1896 rootncp = ncp; 1897 1898 if (ovp) 1899 vrele(ovp); 1900 if (oncp) 1901 cache_drop(oncp); 1902 } 1903 1904 /* 1905 * XXX OLD API COMPAT FUNCTION. This really messes up the new namecache 1906 * topology and is being removed as quickly as possible. The new VOP_N*() 1907 * API calls are required to make specific adjustments using the supplied 1908 * ncp pointers rather then just bogusly purging random vnodes. 1909 * 1910 * Invalidate all namecache entries to a particular vnode as well as 1911 * any direct children of that vnode in the namecache. This is a 1912 * 'catch all' purge used by filesystems that do not know any better. 1913 * 1914 * Note that the linkage between the vnode and its namecache entries will 1915 * be removed, but the namecache entries themselves might stay put due to 1916 * active references from elsewhere in the system or due to the existance of 1917 * the children. The namecache topology is left intact even if we do not 1918 * know what the vnode association is. Such entries will be marked 1919 * NCF_UNRESOLVED. 1920 */ 1921 void 1922 cache_purge(struct vnode *vp) 1923 { 1924 cache_inval_vp(vp, CINV_DESTROY | CINV_CHILDREN); 1925 } 1926 1927 /* 1928 * Flush all entries referencing a particular filesystem. 1929 * 1930 * Since we need to check it anyway, we will flush all the invalid 1931 * entries at the same time. 1932 */ 1933 void 1934 cache_purgevfs(struct mount *mp) 1935 { 1936 struct nchashhead *nchpp; 1937 struct namecache *ncp, *nnp; 1938 1939 /* 1940 * Scan hash tables for applicable entries. 1941 */ 1942 for (nchpp = &nchashtbl[nchash]; nchpp >= nchashtbl; nchpp--) { 1943 ncp = LIST_FIRST(nchpp); 1944 if (ncp) 1945 cache_hold(ncp); 1946 while (ncp) { 1947 nnp = LIST_NEXT(ncp, nc_hash); 1948 if (nnp) 1949 cache_hold(nnp); 1950 if (ncp->nc_mount == mp) { 1951 cache_lock(ncp); 1952 cache_zap(ncp); 1953 } else { 1954 cache_drop(ncp); 1955 } 1956 ncp = nnp; 1957 } 1958 } 1959 } 1960 1961 /* 1962 * Create a new (theoretically) unique fsmid 1963 */ 1964 int64_t 1965 cache_getnewfsmid(void) 1966 { 1967 static int fsmid_roller; 1968 int64_t fsmid; 1969 1970 ++fsmid_roller; 1971 fsmid = ((int64_t)time_second << 32) | 1972 (fsmid_roller & 0x7FFFFFFF); 1973 return (fsmid); 1974 } 1975 1976 1977 static int disablecwd; 1978 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, ""); 1979 1980 static u_long numcwdcalls; STATNODE(CTLFLAG_RD, numcwdcalls, &numcwdcalls); 1981 static u_long numcwdfail1; STATNODE(CTLFLAG_RD, numcwdfail1, &numcwdfail1); 1982 static u_long numcwdfail2; STATNODE(CTLFLAG_RD, numcwdfail2, &numcwdfail2); 1983 static u_long numcwdfail3; STATNODE(CTLFLAG_RD, numcwdfail3, &numcwdfail3); 1984 static u_long numcwdfail4; STATNODE(CTLFLAG_RD, numcwdfail4, &numcwdfail4); 1985 static u_long numcwdfound; STATNODE(CTLFLAG_RD, numcwdfound, &numcwdfound); 1986 1987 int 1988 sys___getcwd(struct __getcwd_args *uap) 1989 { 1990 int buflen; 1991 int error; 1992 char *buf; 1993 char *bp; 1994 1995 if (disablecwd) 1996 return (ENODEV); 1997 1998 buflen = uap->buflen; 1999 if (buflen < 2) 2000 return (EINVAL); 2001 if (buflen > MAXPATHLEN) 2002 buflen = MAXPATHLEN; 2003 2004 buf = kmalloc(buflen, M_TEMP, M_WAITOK); 2005 bp = kern_getcwd(buf, buflen, &error); 2006 if (error == 0) 2007 error = copyout(bp, uap->buf, strlen(bp) + 1); 2008 kfree(buf, M_TEMP); 2009 return (error); 2010 } 2011 2012 char * 2013 kern_getcwd(char *buf, size_t buflen, int *error) 2014 { 2015 struct proc *p = curproc; 2016 char *bp; 2017 int i, slash_prefixed; 2018 struct filedesc *fdp; 2019 struct namecache *ncp; 2020 2021 numcwdcalls++; 2022 bp = buf; 2023 bp += buflen - 1; 2024 *bp = '\0'; 2025 fdp = p->p_fd; 2026 slash_prefixed = 0; 2027 2028 ncp = fdp->fd_ncdir; 2029 while (ncp && ncp != fdp->fd_nrdir && (ncp->nc_flag & NCF_ROOT) == 0) { 2030 if (ncp->nc_flag & NCF_MOUNTPT) { 2031 if (ncp->nc_mount == NULL) { 2032 *error = EBADF; /* forced unmount? */ 2033 return(NULL); 2034 } 2035 ncp = ncp->nc_parent; 2036 continue; 2037 } 2038 for (i = ncp->nc_nlen - 1; i >= 0; i--) { 2039 if (bp == buf) { 2040 numcwdfail4++; 2041 *error = ENOMEM; 2042 return(NULL); 2043 } 2044 *--bp = ncp->nc_name[i]; 2045 } 2046 if (bp == buf) { 2047 numcwdfail4++; 2048 *error = ENOMEM; 2049 return(NULL); 2050 } 2051 *--bp = '/'; 2052 slash_prefixed = 1; 2053 ncp = ncp->nc_parent; 2054 } 2055 if (ncp == NULL) { 2056 numcwdfail2++; 2057 *error = ENOENT; 2058 return(NULL); 2059 } 2060 if (!slash_prefixed) { 2061 if (bp == buf) { 2062 numcwdfail4++; 2063 *error = ENOMEM; 2064 return(NULL); 2065 } 2066 *--bp = '/'; 2067 } 2068 numcwdfound++; 2069 *error = 0; 2070 return (bp); 2071 } 2072 2073 /* 2074 * Thus begins the fullpath magic. 2075 */ 2076 2077 #undef STATNODE 2078 #define STATNODE(name) \ 2079 static u_int name; \ 2080 SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, "") 2081 2082 static int disablefullpath; 2083 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, 2084 &disablefullpath, 0, ""); 2085 2086 STATNODE(numfullpathcalls); 2087 STATNODE(numfullpathfail1); 2088 STATNODE(numfullpathfail2); 2089 STATNODE(numfullpathfail3); 2090 STATNODE(numfullpathfail4); 2091 STATNODE(numfullpathfound); 2092 2093 int 2094 cache_fullpath(struct proc *p, struct namecache *ncp, char **retbuf, char **freebuf) 2095 { 2096 char *bp, *buf; 2097 int i, slash_prefixed; 2098 struct namecache *fd_nrdir; 2099 2100 numfullpathcalls--; 2101 2102 buf = kmalloc(MAXPATHLEN, M_TEMP, M_WAITOK); 2103 bp = buf + MAXPATHLEN - 1; 2104 *bp = '\0'; 2105 if (p != NULL) 2106 fd_nrdir = p->p_fd->fd_nrdir; 2107 else 2108 fd_nrdir = NULL; 2109 slash_prefixed = 0; 2110 while (ncp && ncp != fd_nrdir && (ncp->nc_flag & NCF_ROOT) == 0) { 2111 if (ncp->nc_flag & NCF_MOUNTPT) { 2112 if (ncp->nc_mount == NULL) { 2113 kfree(buf, M_TEMP); 2114 return(EBADF); 2115 } 2116 ncp = ncp->nc_parent; 2117 continue; 2118 } 2119 for (i = ncp->nc_nlen - 1; i >= 0; i--) { 2120 if (bp == buf) { 2121 numfullpathfail4++; 2122 kfree(buf, M_TEMP); 2123 return(ENOMEM); 2124 } 2125 *--bp = ncp->nc_name[i]; 2126 } 2127 if (bp == buf) { 2128 numfullpathfail4++; 2129 kfree(buf, M_TEMP); 2130 return(ENOMEM); 2131 } 2132 *--bp = '/'; 2133 slash_prefixed = 1; 2134 ncp = ncp->nc_parent; 2135 } 2136 if (ncp == NULL) { 2137 numfullpathfail2++; 2138 kfree(buf, M_TEMP); 2139 return(ENOENT); 2140 } 2141 if (p != NULL && (ncp->nc_flag & NCF_ROOT) && ncp != fd_nrdir) { 2142 bp = buf + MAXPATHLEN - 1; 2143 *bp = '\0'; 2144 slash_prefixed = 0; 2145 } 2146 if (!slash_prefixed) { 2147 if (bp == buf) { 2148 numfullpathfail4++; 2149 kfree(buf, M_TEMP); 2150 return(ENOMEM); 2151 } 2152 *--bp = '/'; 2153 } 2154 numfullpathfound++; 2155 *retbuf = bp; 2156 *freebuf = buf; 2157 2158 return(0); 2159 } 2160 2161 int 2162 vn_fullpath(struct proc *p, struct vnode *vn, char **retbuf, char **freebuf) 2163 { 2164 struct namecache *ncp; 2165 2166 numfullpathcalls++; 2167 if (disablefullpath) 2168 return (ENODEV); 2169 2170 if (p == NULL) 2171 return (EINVAL); 2172 2173 /* vn is NULL, client wants us to use p->p_textvp */ 2174 if (vn == NULL) { 2175 if ((vn = p->p_textvp) == NULL) 2176 return (EINVAL); 2177 } 2178 TAILQ_FOREACH(ncp, &vn->v_namecache, nc_vnode) { 2179 if (ncp->nc_nlen) 2180 break; 2181 } 2182 if (ncp == NULL) 2183 return (EINVAL); 2184 2185 numfullpathcalls--; 2186 return(cache_fullpath(p, ncp, retbuf, freebuf)); 2187 } 2188