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 1.86 2008/01/18 19:13:15 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 #include <sys/sysref2.h> 92 93 #define MAX_RECURSION_DEPTH 64 94 95 /* 96 * Random lookups in the cache are accomplished with a hash table using 97 * a hash key of (nc_src_vp, name). 98 * 99 * Negative entries may exist and correspond to structures where nc_vp 100 * is NULL. In a negative entry, NCF_WHITEOUT will be set if the entry 101 * corresponds to a whited-out directory entry (verses simply not finding the 102 * entry at all). 103 * 104 * Upon reaching the last segment of a path, if the reference is for DELETE, 105 * or NOCACHE is set (rewrite), and the name is located in the cache, it 106 * will be dropped. 107 */ 108 109 /* 110 * Structures associated with name cacheing. 111 */ 112 #define NCHHASH(hash) (&nchashtbl[(hash) & nchash]) 113 #define MINNEG 1024 114 115 MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); 116 117 static LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */ 118 static struct namecache_list ncneglist; /* instead of vnode */ 119 120 /* 121 * ncvp_debug - debug cache_fromvp(). This is used by the NFS server 122 * to create the namecache infrastructure leading to a dangling vnode. 123 * 124 * 0 Only errors are reported 125 * 1 Successes are reported 126 * 2 Successes + the whole directory scan is reported 127 * 3 Force the directory scan code run as if the parent vnode did not 128 * have a namecache record, even if it does have one. 129 */ 130 static int ncvp_debug; 131 SYSCTL_INT(_debug, OID_AUTO, ncvp_debug, CTLFLAG_RW, &ncvp_debug, 0, ""); 132 133 static u_long nchash; /* size of hash table */ 134 SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, ""); 135 136 static u_long ncnegfactor = 16; /* ratio of negative entries */ 137 SYSCTL_ULONG(_debug, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, ""); 138 139 static int nclockwarn; /* warn on locked entries in ticks */ 140 SYSCTL_INT(_debug, OID_AUTO, nclockwarn, CTLFLAG_RW, &nclockwarn, 0, ""); 141 142 static u_long numneg; /* number of cache entries allocated */ 143 SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, ""); 144 145 static u_long numcache; /* number of cache entries allocated */ 146 SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, ""); 147 148 static u_long numunres; /* number of unresolved entries */ 149 SYSCTL_ULONG(_debug, OID_AUTO, numunres, CTLFLAG_RD, &numunres, 0, ""); 150 151 SYSCTL_INT(_debug, OID_AUTO, vnsize, CTLFLAG_RD, 0, sizeof(struct vnode), ""); 152 SYSCTL_INT(_debug, OID_AUTO, ncsize, CTLFLAG_RD, 0, sizeof(struct namecache), ""); 153 154 static int cache_resolve_mp(struct mount *mp); 155 static void _cache_rehash(struct namecache *ncp); 156 static void _cache_lock(struct namecache *ncp); 157 static void _cache_setunresolved(struct namecache *ncp); 158 159 /* 160 * The new name cache statistics 161 */ 162 SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, "Name cache statistics"); 163 #define STATNODE(mode, name, var) \ 164 SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, mode, var, 0, ""); 165 STATNODE(CTLFLAG_RD, numneg, &numneg); 166 STATNODE(CTLFLAG_RD, numcache, &numcache); 167 static u_long numcalls; STATNODE(CTLFLAG_RD, numcalls, &numcalls); 168 static u_long dothits; STATNODE(CTLFLAG_RD, dothits, &dothits); 169 static u_long dotdothits; STATNODE(CTLFLAG_RD, dotdothits, &dotdothits); 170 static u_long numchecks; STATNODE(CTLFLAG_RD, numchecks, &numchecks); 171 static u_long nummiss; STATNODE(CTLFLAG_RD, nummiss, &nummiss); 172 static u_long nummisszap; STATNODE(CTLFLAG_RD, nummisszap, &nummisszap); 173 static u_long numposzaps; STATNODE(CTLFLAG_RD, numposzaps, &numposzaps); 174 static u_long numposhits; STATNODE(CTLFLAG_RD, numposhits, &numposhits); 175 static u_long numnegzaps; STATNODE(CTLFLAG_RD, numnegzaps, &numnegzaps); 176 static u_long numneghits; STATNODE(CTLFLAG_RD, numneghits, &numneghits); 177 178 struct nchstats nchstats[SMP_MAXCPU]; 179 /* 180 * Export VFS cache effectiveness statistics to user-land. 181 * 182 * The statistics are left for aggregation to user-land so 183 * neat things can be achieved, like observing per-CPU cache 184 * distribution. 185 */ 186 static int 187 sysctl_nchstats(SYSCTL_HANDLER_ARGS) 188 { 189 struct globaldata *gd; 190 int i, error; 191 192 error = 0; 193 for (i = 0; i < ncpus; ++i) { 194 gd = globaldata_find(i); 195 if ((error = SYSCTL_OUT(req, (void *)&(*gd->gd_nchstats), 196 sizeof(struct nchstats)))) 197 break; 198 } 199 200 return (error); 201 } 202 SYSCTL_PROC(_vfs_cache, OID_AUTO, nchstats, CTLTYPE_OPAQUE|CTLFLAG_RD, 203 0, 0, sysctl_nchstats, "S,nchstats", "VFS cache effectiveness statistics"); 204 205 static void cache_zap(struct namecache *ncp); 206 207 /* 208 * cache_hold() and cache_drop() prevent the premature deletion of a 209 * namecache entry but do not prevent operations (such as zapping) on 210 * that namecache entry. 211 * 212 * This routine may only be called from outside this source module if 213 * nc_refs is already at least 1. 214 * 215 * This is a rare case where callers are allowed to hold a spinlock, 216 * so we can't ourselves. 217 */ 218 static __inline 219 struct namecache * 220 _cache_hold(struct namecache *ncp) 221 { 222 atomic_add_int(&ncp->nc_refs, 1); 223 return(ncp); 224 } 225 226 /* 227 * When dropping an entry, if only one ref remains and the entry has not 228 * been resolved, zap it. Since the one reference is being dropped the 229 * entry had better not be locked. 230 */ 231 static __inline 232 void 233 _cache_drop(struct namecache *ncp) 234 { 235 KKASSERT(ncp->nc_refs > 0); 236 if (ncp->nc_refs == 1 && 237 (ncp->nc_flag & NCF_UNRESOLVED) && 238 TAILQ_EMPTY(&ncp->nc_list) 239 ) { 240 KKASSERT(ncp->nc_exlocks == 0); 241 _cache_lock(ncp); 242 cache_zap(ncp); 243 } else { 244 atomic_subtract_int(&ncp->nc_refs, 1); 245 } 246 } 247 248 /* 249 * Link a new namecache entry to its parent. Be careful to avoid races 250 * if vhold() blocks in the future. 251 */ 252 static void 253 cache_link_parent(struct namecache *ncp, struct namecache *par) 254 { 255 KKASSERT(ncp->nc_parent == NULL); 256 ncp->nc_parent = par; 257 if (TAILQ_EMPTY(&par->nc_list)) { 258 TAILQ_INSERT_HEAD(&par->nc_list, ncp, nc_entry); 259 /* 260 * Any vp associated with an ncp which has children must 261 * be held to prevent it from being recycled. 262 */ 263 if (par->nc_vp) 264 vhold(par->nc_vp); 265 } else { 266 TAILQ_INSERT_HEAD(&par->nc_list, ncp, nc_entry); 267 } 268 } 269 270 /* 271 * Remove the parent association from a namecache structure. If this is 272 * the last child of the parent the cache_drop(par) will attempt to 273 * recursively zap the parent. 274 */ 275 static void 276 cache_unlink_parent(struct namecache *ncp) 277 { 278 struct namecache *par; 279 280 if ((par = ncp->nc_parent) != NULL) { 281 ncp->nc_parent = NULL; 282 par = _cache_hold(par); 283 TAILQ_REMOVE(&par->nc_list, ncp, nc_entry); 284 if (par->nc_vp && TAILQ_EMPTY(&par->nc_list)) 285 vdrop(par->nc_vp); 286 _cache_drop(par); 287 } 288 } 289 290 /* 291 * Allocate a new namecache structure. Most of the code does not require 292 * zero-termination of the string but it makes vop_compat_ncreate() easier. 293 */ 294 static struct namecache * 295 cache_alloc(int nlen) 296 { 297 struct namecache *ncp; 298 299 ncp = kmalloc(sizeof(*ncp), M_VFSCACHE, M_WAITOK|M_ZERO); 300 if (nlen) 301 ncp->nc_name = kmalloc(nlen + 1, M_VFSCACHE, M_WAITOK); 302 ncp->nc_nlen = nlen; 303 ncp->nc_flag = NCF_UNRESOLVED; 304 ncp->nc_error = ENOTCONN; /* needs to be resolved */ 305 ncp->nc_refs = 1; 306 307 /* 308 * Construct a fake FSMID based on the time of day and a 32 bit 309 * roller for uniqueness. This is used to generate a useful 310 * FSMID for filesystems which do not support it. 311 */ 312 ncp->nc_fsmid = cache_getnewfsmid(); 313 TAILQ_INIT(&ncp->nc_list); 314 _cache_lock(ncp); 315 return(ncp); 316 } 317 318 static void 319 _cache_free(struct namecache *ncp) 320 { 321 KKASSERT(ncp->nc_refs == 1 && ncp->nc_exlocks == 1); 322 if (ncp->nc_name) 323 kfree(ncp->nc_name, M_VFSCACHE); 324 kfree(ncp, M_VFSCACHE); 325 } 326 327 void 328 cache_zero(struct nchandle *nch) 329 { 330 nch->ncp = NULL; 331 nch->mount = NULL; 332 } 333 334 /* 335 * Ref and deref a namecache structure. 336 * 337 * Warning: caller may hold an unrelated read spinlock, which means we can't 338 * use read spinlocks here. 339 */ 340 struct nchandle * 341 cache_hold(struct nchandle *nch) 342 { 343 _cache_hold(nch->ncp); 344 ++nch->mount->mnt_refs; 345 return(nch); 346 } 347 348 void 349 cache_copy(struct nchandle *nch, struct nchandle *target) 350 { 351 *target = *nch; 352 _cache_hold(target->ncp); 353 ++nch->mount->mnt_refs; 354 } 355 356 void 357 cache_changemount(struct nchandle *nch, struct mount *mp) 358 { 359 --nch->mount->mnt_refs; 360 nch->mount = mp; 361 ++nch->mount->mnt_refs; 362 } 363 364 void 365 cache_drop(struct nchandle *nch) 366 { 367 --nch->mount->mnt_refs; 368 _cache_drop(nch->ncp); 369 nch->ncp = NULL; 370 nch->mount = NULL; 371 } 372 373 /* 374 * Namespace locking. The caller must already hold a reference to the 375 * namecache structure in order to lock/unlock it. This function prevents 376 * the namespace from being created or destroyed by accessors other then 377 * the lock holder. 378 * 379 * Note that holding a locked namecache structure prevents other threads 380 * from making namespace changes (e.g. deleting or creating), prevents 381 * vnode association state changes by other threads, and prevents the 382 * namecache entry from being resolved or unresolved by other threads. 383 * 384 * The lock owner has full authority to associate/disassociate vnodes 385 * and resolve/unresolve the locked ncp. 386 * 387 * WARNING! Holding a locked ncp will prevent a vnode from being destroyed 388 * or recycled, but it does NOT help you if the vnode had already initiated 389 * a recyclement. If this is important, use cache_get() rather then 390 * cache_lock() (and deal with the differences in the way the refs counter 391 * is handled). Or, alternatively, make an unconditional call to 392 * cache_validate() or cache_resolve() after cache_lock() returns. 393 */ 394 static 395 void 396 _cache_lock(struct namecache *ncp) 397 { 398 thread_t td; 399 int didwarn; 400 401 KKASSERT(ncp->nc_refs != 0); 402 didwarn = 0; 403 td = curthread; 404 405 for (;;) { 406 if (ncp->nc_exlocks == 0) { 407 ncp->nc_exlocks = 1; 408 ncp->nc_locktd = td; 409 /* 410 * The vp associated with a locked ncp must be held 411 * to prevent it from being recycled (which would 412 * cause the ncp to become unresolved). 413 * 414 * WARNING! If VRECLAIMED is set the vnode could 415 * already be in the middle of a recycle. Callers 416 * should not assume that nc_vp is usable when 417 * not NULL. cache_vref() or cache_vget() must be 418 * called. 419 * 420 * XXX loop on race for later MPSAFE work. 421 */ 422 if (ncp->nc_vp) 423 vhold(ncp->nc_vp); 424 break; 425 } 426 if (ncp->nc_locktd == td) { 427 ++ncp->nc_exlocks; 428 break; 429 } 430 ncp->nc_flag |= NCF_LOCKREQ; 431 if (tsleep(ncp, 0, "clock", nclockwarn) == EWOULDBLOCK) { 432 if (didwarn) 433 continue; 434 didwarn = 1; 435 kprintf("[diagnostic] cache_lock: blocked on %p", ncp); 436 kprintf(" \"%*.*s\"\n", 437 ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name); 438 } 439 } 440 441 if (didwarn == 1) { 442 kprintf("[diagnostic] cache_lock: unblocked %*.*s\n", 443 ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name); 444 } 445 } 446 447 void 448 cache_lock(struct nchandle *nch) 449 { 450 _cache_lock(nch->ncp); 451 } 452 453 static 454 int 455 _cache_lock_nonblock(struct namecache *ncp) 456 { 457 thread_t td; 458 459 KKASSERT(ncp->nc_refs != 0); 460 td = curthread; 461 if (ncp->nc_exlocks == 0) { 462 ncp->nc_exlocks = 1; 463 ncp->nc_locktd = td; 464 /* 465 * The vp associated with a locked ncp must be held 466 * to prevent it from being recycled (which would 467 * cause the ncp to become unresolved). 468 * 469 * WARNING! If VRECLAIMED is set the vnode could 470 * already be in the middle of a recycle. Callers 471 * should not assume that nc_vp is usable when 472 * not NULL. cache_vref() or cache_vget() must be 473 * called. 474 * 475 * XXX loop on race for later MPSAFE work. 476 */ 477 if (ncp->nc_vp) 478 vhold(ncp->nc_vp); 479 return(0); 480 } else { 481 return(EWOULDBLOCK); 482 } 483 } 484 485 int 486 cache_lock_nonblock(struct nchandle *nch) 487 { 488 return(_cache_lock_nonblock(nch->ncp)); 489 } 490 491 static 492 void 493 _cache_unlock(struct namecache *ncp) 494 { 495 thread_t td = curthread; 496 497 KKASSERT(ncp->nc_refs > 0); 498 KKASSERT(ncp->nc_exlocks > 0); 499 KKASSERT(ncp->nc_locktd == td); 500 if (--ncp->nc_exlocks == 0) { 501 if (ncp->nc_vp) 502 vdrop(ncp->nc_vp); 503 ncp->nc_locktd = NULL; 504 if (ncp->nc_flag & NCF_LOCKREQ) { 505 ncp->nc_flag &= ~NCF_LOCKREQ; 506 wakeup(ncp); 507 } 508 } 509 } 510 511 void 512 cache_unlock(struct nchandle *nch) 513 { 514 _cache_unlock(nch->ncp); 515 } 516 517 /* 518 * ref-and-lock, unlock-and-deref functions. 519 * 520 * This function is primarily used by nlookup. Even though cache_lock 521 * holds the vnode, it is possible that the vnode may have already 522 * initiated a recyclement. We want cache_get() to return a definitively 523 * usable vnode or a definitively unresolved ncp. 524 */ 525 static 526 struct namecache * 527 _cache_get(struct namecache *ncp) 528 { 529 _cache_hold(ncp); 530 _cache_lock(ncp); 531 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) 532 _cache_setunresolved(ncp); 533 return(ncp); 534 } 535 536 /* 537 * note: the same nchandle can be passed for both arguments. 538 */ 539 void 540 cache_get(struct nchandle *nch, struct nchandle *target) 541 { 542 target->mount = nch->mount; 543 target->ncp = _cache_get(nch->ncp); 544 ++target->mount->mnt_refs; 545 } 546 547 static int 548 _cache_get_nonblock(struct namecache *ncp) 549 { 550 /* XXX MP */ 551 if (ncp->nc_exlocks == 0 || ncp->nc_locktd == curthread) { 552 _cache_hold(ncp); 553 _cache_lock(ncp); 554 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) 555 _cache_setunresolved(ncp); 556 return(0); 557 } 558 return(EWOULDBLOCK); 559 } 560 561 int 562 cache_get_nonblock(struct nchandle *nch) 563 { 564 return(_cache_get_nonblock(nch->ncp)); 565 } 566 567 static __inline 568 void 569 _cache_put(struct namecache *ncp) 570 { 571 _cache_unlock(ncp); 572 _cache_drop(ncp); 573 } 574 575 void 576 cache_put(struct nchandle *nch) 577 { 578 --nch->mount->mnt_refs; 579 _cache_put(nch->ncp); 580 nch->ncp = NULL; 581 nch->mount = NULL; 582 } 583 584 /* 585 * Resolve an unresolved ncp by associating a vnode with it. If the 586 * vnode is NULL, a negative cache entry is created. 587 * 588 * The ncp should be locked on entry and will remain locked on return. 589 */ 590 static 591 void 592 _cache_setvp(struct namecache *ncp, struct vnode *vp) 593 { 594 KKASSERT(ncp->nc_flag & NCF_UNRESOLVED); 595 ncp->nc_vp = vp; 596 if (vp != NULL) { 597 /* 598 * Any vp associated with an ncp which has children must 599 * be held. Any vp associated with a locked ncp must be held. 600 */ 601 if (!TAILQ_EMPTY(&ncp->nc_list)) 602 vhold(vp); 603 TAILQ_INSERT_HEAD(&vp->v_namecache, ncp, nc_vnode); 604 if (ncp->nc_exlocks) 605 vhold(vp); 606 607 /* 608 * Set auxiliary flags 609 */ 610 switch(vp->v_type) { 611 case VDIR: 612 ncp->nc_flag |= NCF_ISDIR; 613 break; 614 case VLNK: 615 ncp->nc_flag |= NCF_ISSYMLINK; 616 /* XXX cache the contents of the symlink */ 617 break; 618 default: 619 break; 620 } 621 ++numcache; 622 ncp->nc_error = 0; 623 } else { 624 TAILQ_INSERT_TAIL(&ncneglist, ncp, nc_vnode); 625 ++numneg; 626 ncp->nc_error = ENOENT; 627 } 628 ncp->nc_flag &= ~NCF_UNRESOLVED; 629 } 630 631 void 632 cache_setvp(struct nchandle *nch, struct vnode *vp) 633 { 634 _cache_setvp(nch->ncp, vp); 635 } 636 637 void 638 cache_settimeout(struct nchandle *nch, int nticks) 639 { 640 struct namecache *ncp = nch->ncp; 641 642 if ((ncp->nc_timeout = ticks + nticks) == 0) 643 ncp->nc_timeout = 1; 644 } 645 646 /* 647 * Disassociate the vnode or negative-cache association and mark a 648 * namecache entry as unresolved again. Note that the ncp is still 649 * left in the hash table and still linked to its parent. 650 * 651 * The ncp should be locked and refd on entry and will remain locked and refd 652 * on return. 653 * 654 * This routine is normally never called on a directory containing children. 655 * However, NFS often does just that in its rename() code as a cop-out to 656 * avoid complex namespace operations. This disconnects a directory vnode 657 * from its namecache and can cause the OLDAPI and NEWAPI to get out of 658 * sync. 659 * 660 * NOTE: NCF_FSMID must be cleared so a refurbishment of the ncp, such as 661 * in a create, properly propogates flag up the chain. 662 */ 663 static 664 void 665 _cache_setunresolved(struct namecache *ncp) 666 { 667 struct vnode *vp; 668 669 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) { 670 ncp->nc_flag |= NCF_UNRESOLVED; 671 ncp->nc_timeout = 0; 672 ncp->nc_error = ENOTCONN; 673 ++numunres; 674 if ((vp = ncp->nc_vp) != NULL) { 675 --numcache; 676 ncp->nc_vp = NULL; 677 TAILQ_REMOVE(&vp->v_namecache, ncp, nc_vnode); 678 679 /* 680 * Any vp associated with an ncp with children is 681 * held by that ncp. Any vp associated with a locked 682 * ncp is held by that ncp. These conditions must be 683 * undone when the vp is cleared out from the ncp. 684 */ 685 if (ncp->nc_flag & NCF_FSMID) 686 vupdatefsmid(vp); 687 if (!TAILQ_EMPTY(&ncp->nc_list)) 688 vdrop(vp); 689 if (ncp->nc_exlocks) 690 vdrop(vp); 691 } else { 692 TAILQ_REMOVE(&ncneglist, ncp, nc_vnode); 693 --numneg; 694 } 695 ncp->nc_flag &= ~(NCF_WHITEOUT|NCF_ISDIR|NCF_ISSYMLINK| 696 NCF_FSMID); 697 } 698 } 699 700 void 701 cache_setunresolved(struct nchandle *nch) 702 { 703 _cache_setunresolved(nch->ncp); 704 } 705 706 /* 707 * Determine if we can clear NCF_ISMOUNTPT by scanning the mountlist 708 * looking for matches. This flag tells the lookup code when it must 709 * check for a mount linkage and also prevents the directories in question 710 * from being deleted or renamed. 711 */ 712 static 713 int 714 cache_clrmountpt_callback(struct mount *mp, void *data) 715 { 716 struct nchandle *nch = data; 717 718 if (mp->mnt_ncmounton.ncp == nch->ncp) 719 return(1); 720 if (mp->mnt_ncmountpt.ncp == nch->ncp) 721 return(1); 722 return(0); 723 } 724 725 void 726 cache_clrmountpt(struct nchandle *nch) 727 { 728 int count; 729 730 count = mountlist_scan(cache_clrmountpt_callback, nch, 731 MNTSCAN_FORWARD|MNTSCAN_NOBUSY); 732 if (count == 0) 733 nch->ncp->nc_flag &= ~NCF_ISMOUNTPT; 734 } 735 736 /* 737 * Invalidate portions of the namecache topology given a starting entry. 738 * The passed ncp is set to an unresolved state and: 739 * 740 * The passed ncp must be locked. 741 * 742 * CINV_DESTROY - Set a flag in the passed ncp entry indicating 743 * that the physical underlying nodes have been 744 * destroyed... as in deleted. For example, when 745 * a directory is removed. This will cause record 746 * lookups on the name to no longer be able to find 747 * the record and tells the resolver to return failure 748 * rather then trying to resolve through the parent. 749 * 750 * The topology itself, including ncp->nc_name, 751 * remains intact. 752 * 753 * This only applies to the passed ncp, if CINV_CHILDREN 754 * is specified the children are not flagged. 755 * 756 * CINV_CHILDREN - Set all children (recursively) to an unresolved 757 * state as well. 758 * 759 * Note that this will also have the side effect of 760 * cleaning out any unreferenced nodes in the topology 761 * from the leaves up as the recursion backs out. 762 * 763 * Note that the topology for any referenced nodes remains intact. 764 * 765 * It is possible for cache_inval() to race a cache_resolve(), meaning that 766 * the namecache entry may not actually be invalidated on return if it was 767 * revalidated while recursing down into its children. This code guarentees 768 * that the node(s) will go through an invalidation cycle, but does not 769 * guarentee that they will remain in an invalidated state. 770 * 771 * Returns non-zero if a revalidation was detected during the invalidation 772 * recursion, zero otherwise. Note that since only the original ncp is 773 * locked the revalidation ultimately can only indicate that the original ncp 774 * *MIGHT* no have been reresolved. 775 * 776 * DEEP RECURSION HANDLING - If a recursive invalidation recurses deeply we 777 * have to avoid blowing out the kernel stack. We do this by saving the 778 * deep namecache node and aborting the recursion, then re-recursing at that 779 * node using a depth-first algorithm in order to allow multiple deep 780 * recursions to chain through each other, then we restart the invalidation 781 * from scratch. 782 */ 783 784 struct cinvtrack { 785 struct namecache *resume_ncp; 786 int depth; 787 }; 788 789 static int _cache_inval_internal(struct namecache *, int, struct cinvtrack *); 790 791 static 792 int 793 _cache_inval(struct namecache *ncp, int flags) 794 { 795 struct cinvtrack track; 796 struct namecache *ncp2; 797 int r; 798 799 track.depth = 0; 800 track.resume_ncp = NULL; 801 802 for (;;) { 803 r = _cache_inval_internal(ncp, flags, &track); 804 if (track.resume_ncp == NULL) 805 break; 806 kprintf("Warning: deep namecache recursion at %s\n", 807 ncp->nc_name); 808 _cache_unlock(ncp); 809 while ((ncp2 = track.resume_ncp) != NULL) { 810 track.resume_ncp = NULL; 811 _cache_lock(ncp2); 812 _cache_inval_internal(ncp2, flags & ~CINV_DESTROY, 813 &track); 814 _cache_put(ncp2); 815 } 816 _cache_lock(ncp); 817 } 818 return(r); 819 } 820 821 int 822 cache_inval(struct nchandle *nch, int flags) 823 { 824 return(_cache_inval(nch->ncp, flags)); 825 } 826 827 static int 828 _cache_inval_internal(struct namecache *ncp, int flags, struct cinvtrack *track) 829 { 830 struct namecache *kid; 831 struct namecache *nextkid; 832 int rcnt = 0; 833 834 KKASSERT(ncp->nc_exlocks); 835 836 _cache_setunresolved(ncp); 837 if (flags & CINV_DESTROY) 838 ncp->nc_flag |= NCF_DESTROYED; 839 840 if ((flags & CINV_CHILDREN) && 841 (kid = TAILQ_FIRST(&ncp->nc_list)) != NULL 842 ) { 843 if (++track->depth > MAX_RECURSION_DEPTH) { 844 track->resume_ncp = ncp; 845 _cache_hold(ncp); 846 ++rcnt; 847 } 848 _cache_hold(kid); 849 _cache_unlock(ncp); 850 while (kid) { 851 if (track->resume_ncp) { 852 _cache_drop(kid); 853 break; 854 } 855 if ((nextkid = TAILQ_NEXT(kid, nc_entry)) != NULL) 856 _cache_hold(nextkid); 857 if ((kid->nc_flag & NCF_UNRESOLVED) == 0 || 858 TAILQ_FIRST(&kid->nc_list) 859 ) { 860 _cache_lock(kid); 861 rcnt += _cache_inval_internal(kid, flags & ~CINV_DESTROY, track); 862 _cache_unlock(kid); 863 } 864 _cache_drop(kid); 865 kid = nextkid; 866 } 867 --track->depth; 868 _cache_lock(ncp); 869 } 870 871 /* 872 * Someone could have gotten in there while ncp was unlocked, 873 * retry if so. 874 */ 875 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) 876 ++rcnt; 877 return (rcnt); 878 } 879 880 /* 881 * Invalidate a vnode's namecache associations. To avoid races against 882 * the resolver we do not invalidate a node which we previously invalidated 883 * but which was then re-resolved while we were in the invalidation loop. 884 * 885 * Returns non-zero if any namecache entries remain after the invalidation 886 * loop completed. 887 * 888 * NOTE: unlike the namecache topology which guarentees that ncp's will not 889 * be ripped out of the topology while held, the vnode's v_namecache list 890 * has no such restriction. NCP's can be ripped out of the list at virtually 891 * any time if not locked, even if held. 892 */ 893 int 894 cache_inval_vp(struct vnode *vp, int flags) 895 { 896 struct namecache *ncp; 897 struct namecache *next; 898 899 restart: 900 ncp = TAILQ_FIRST(&vp->v_namecache); 901 if (ncp) 902 _cache_hold(ncp); 903 while (ncp) { 904 /* loop entered with ncp held */ 905 if ((next = TAILQ_NEXT(ncp, nc_vnode)) != NULL) 906 _cache_hold(next); 907 _cache_lock(ncp); 908 if (ncp->nc_vp != vp) { 909 kprintf("Warning: cache_inval_vp: race-A detected on " 910 "%s\n", ncp->nc_name); 911 _cache_put(ncp); 912 if (next) 913 _cache_drop(next); 914 goto restart; 915 } 916 _cache_inval(ncp, flags); 917 _cache_put(ncp); /* also releases reference */ 918 ncp = next; 919 if (ncp && ncp->nc_vp != vp) { 920 kprintf("Warning: cache_inval_vp: race-B detected on " 921 "%s\n", ncp->nc_name); 922 _cache_drop(ncp); 923 goto restart; 924 } 925 } 926 return(TAILQ_FIRST(&vp->v_namecache) != NULL); 927 } 928 929 /* 930 * This routine is used instead of the normal cache_inval_vp() when we 931 * are trying to recycle otherwise good vnodes. 932 * 933 * Return 0 on success, non-zero if not all namecache records could be 934 * disassociated from the vnode (for various reasons). 935 */ 936 int 937 cache_inval_vp_nonblock(struct vnode *vp) 938 { 939 struct namecache *ncp; 940 struct namecache *next; 941 942 ncp = TAILQ_FIRST(&vp->v_namecache); 943 if (ncp) 944 _cache_hold(ncp); 945 while (ncp) { 946 /* loop entered with ncp held */ 947 if ((next = TAILQ_NEXT(ncp, nc_vnode)) != NULL) 948 _cache_hold(next); 949 if (_cache_lock_nonblock(ncp)) { 950 _cache_drop(ncp); 951 if (next) 952 _cache_drop(next); 953 break; 954 } 955 if (ncp->nc_vp != vp) { 956 kprintf("Warning: cache_inval_vp: race-A detected on " 957 "%s\n", ncp->nc_name); 958 _cache_put(ncp); 959 if (next) 960 _cache_drop(next); 961 break; 962 } 963 _cache_inval(ncp, 0); 964 _cache_put(ncp); /* also releases reference */ 965 ncp = next; 966 if (ncp && ncp->nc_vp != vp) { 967 kprintf("Warning: cache_inval_vp: race-B detected on " 968 "%s\n", ncp->nc_name); 969 _cache_drop(ncp); 970 break; 971 } 972 } 973 return(TAILQ_FIRST(&vp->v_namecache) != NULL); 974 } 975 976 /* 977 * The source ncp has been renamed to the target ncp. Both fncp and tncp 978 * must be locked. The target ncp is destroyed (as a normal rename-over 979 * would destroy the target file or directory). 980 * 981 * Because there may be references to the source ncp we cannot copy its 982 * contents to the target. Instead the source ncp is relinked as the target 983 * and the target ncp is removed from the namecache topology. 984 */ 985 void 986 cache_rename(struct nchandle *fnch, struct nchandle *tnch) 987 { 988 struct namecache *fncp = fnch->ncp; 989 struct namecache *tncp = tnch->ncp; 990 char *oname; 991 992 _cache_setunresolved(tncp); 993 cache_unlink_parent(fncp); 994 cache_link_parent(fncp, tncp->nc_parent); 995 cache_unlink_parent(tncp); 996 oname = fncp->nc_name; 997 fncp->nc_name = tncp->nc_name; 998 fncp->nc_nlen = tncp->nc_nlen; 999 tncp->nc_name = NULL; 1000 tncp->nc_nlen = 0; 1001 if (fncp->nc_flag & NCF_HASHED) 1002 _cache_rehash(fncp); 1003 if (tncp->nc_flag & NCF_HASHED) 1004 _cache_rehash(tncp); 1005 if (oname) 1006 kfree(oname, M_VFSCACHE); 1007 } 1008 1009 /* 1010 * vget the vnode associated with the namecache entry. Resolve the namecache 1011 * entry if necessary and deal with namecache/vp races. The passed ncp must 1012 * be referenced and may be locked. The ncp's ref/locking state is not 1013 * effected by this call. 1014 * 1015 * lk_type may be LK_SHARED, LK_EXCLUSIVE. A ref'd, possibly locked 1016 * (depending on the passed lk_type) will be returned in *vpp with an error 1017 * of 0, or NULL will be returned in *vpp with a non-0 error code. The 1018 * most typical error is ENOENT, meaning that the ncp represents a negative 1019 * cache hit and there is no vnode to retrieve, but other errors can occur 1020 * too. 1021 * 1022 * The main race we have to deal with are namecache zaps. The ncp itself 1023 * will not disappear since it is referenced, and it turns out that the 1024 * validity of the vp pointer can be checked simply by rechecking the 1025 * contents of ncp->nc_vp. 1026 */ 1027 int 1028 cache_vget(struct nchandle *nch, struct ucred *cred, 1029 int lk_type, struct vnode **vpp) 1030 { 1031 struct namecache *ncp; 1032 struct vnode *vp; 1033 int error; 1034 1035 ncp = nch->ncp; 1036 again: 1037 vp = NULL; 1038 if (ncp->nc_flag & NCF_UNRESOLVED) { 1039 _cache_lock(ncp); 1040 error = cache_resolve(nch, cred); 1041 _cache_unlock(ncp); 1042 } else { 1043 error = 0; 1044 } 1045 if (error == 0 && (vp = ncp->nc_vp) != NULL) { 1046 /* 1047 * Accessing the vnode from the namecache is a bit 1048 * dangerous. Because there are no refs on the vnode, it 1049 * could be in the middle of a reclaim. 1050 */ 1051 if (vp->v_flag & VRECLAIMED) { 1052 kprintf("Warning: vnode reclaim race detected in cache_vget on %p (%s)\n", vp, ncp->nc_name); 1053 _cache_lock(ncp); 1054 _cache_setunresolved(ncp); 1055 _cache_unlock(ncp); 1056 goto again; 1057 } 1058 error = vget(vp, lk_type); 1059 if (error) { 1060 if (vp != ncp->nc_vp) 1061 goto again; 1062 vp = NULL; 1063 } else if (vp != ncp->nc_vp) { 1064 vput(vp); 1065 goto again; 1066 } else if (vp->v_flag & VRECLAIMED) { 1067 panic("vget succeeded on a VRECLAIMED node! vp %p", vp); 1068 } 1069 } 1070 if (error == 0 && vp == NULL) 1071 error = ENOENT; 1072 *vpp = vp; 1073 return(error); 1074 } 1075 1076 int 1077 cache_vref(struct nchandle *nch, struct ucred *cred, struct vnode **vpp) 1078 { 1079 struct namecache *ncp; 1080 struct vnode *vp; 1081 int error; 1082 1083 ncp = nch->ncp; 1084 1085 again: 1086 vp = NULL; 1087 if (ncp->nc_flag & NCF_UNRESOLVED) { 1088 _cache_lock(ncp); 1089 error = cache_resolve(nch, cred); 1090 _cache_unlock(ncp); 1091 } else { 1092 error = 0; 1093 } 1094 if (error == 0 && (vp = ncp->nc_vp) != NULL) { 1095 /* 1096 * Since we did not obtain any locks, a cache zap 1097 * race can occur here if the vnode is in the middle 1098 * of being reclaimed and has not yet been able to 1099 * clean out its cache node. If that case occurs, 1100 * we must lock and unresolve the cache, then loop 1101 * to retry. 1102 */ 1103 if ((error = vget(vp, LK_SHARED)) != 0) { 1104 if (error == ENOENT) { 1105 kprintf("Warning: vnode reclaim race detected on cache_vref %p (%s)\n", vp, ncp->nc_name); 1106 _cache_lock(ncp); 1107 _cache_setunresolved(ncp); 1108 _cache_unlock(ncp); 1109 goto again; 1110 } 1111 /* fatal error */ 1112 } else { 1113 /* caller does not want a lock */ 1114 vn_unlock(vp); 1115 } 1116 } 1117 if (error == 0 && vp == NULL) 1118 error = ENOENT; 1119 *vpp = vp; 1120 return(error); 1121 } 1122 1123 /* 1124 * Recursively set the FSMID update flag for namecache nodes leading 1125 * to root. This will cause the next getattr or reclaim to increment the 1126 * fsmid and mark the inode for lazy updating. 1127 * 1128 * Stop recursing when we hit a node whos NCF_FSMID flag is already set. 1129 * This makes FSMIDs work in an Einsteinian fashion - where the observation 1130 * effects the result. In this case a program monitoring a higher level 1131 * node will have detected some prior change and started its scan (clearing 1132 * NCF_FSMID in higher level nodes), but since it has not yet observed the 1133 * node where we find NCF_FSMID still set, we can safely make the related 1134 * modification without interfering with the theorized program. 1135 * 1136 * This also means that FSMIDs cannot represent time-domain quantities 1137 * in a hierarchical sense. But the main reason for doing it this way 1138 * is to reduce the amount of recursion that occurs in the critical path 1139 * when e.g. a program is writing to a file that sits deep in a directory 1140 * hierarchy. 1141 */ 1142 void 1143 cache_update_fsmid(struct nchandle *nch) 1144 { 1145 struct namecache *ncp; 1146 struct namecache *scan; 1147 struct vnode *vp; 1148 1149 ncp = nch->ncp; 1150 1151 /* 1152 * Warning: even if we get a non-NULL vp it could still be in the 1153 * middle of a recyclement. Don't do anything fancy, just set 1154 * NCF_FSMID. 1155 */ 1156 if ((vp = ncp->nc_vp) != NULL) { 1157 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) { 1158 for (scan = ncp; scan; scan = scan->nc_parent) { 1159 if (scan->nc_flag & NCF_FSMID) 1160 break; 1161 scan->nc_flag |= NCF_FSMID; 1162 } 1163 } 1164 } else { 1165 while (ncp && (ncp->nc_flag & NCF_FSMID) == 0) { 1166 ncp->nc_flag |= NCF_FSMID; 1167 ncp = ncp->nc_parent; 1168 } 1169 } 1170 } 1171 1172 void 1173 cache_update_fsmid_vp(struct vnode *vp) 1174 { 1175 struct namecache *ncp; 1176 struct namecache *scan; 1177 1178 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) { 1179 for (scan = ncp; scan; scan = scan->nc_parent) { 1180 if (scan->nc_flag & NCF_FSMID) 1181 break; 1182 scan->nc_flag |= NCF_FSMID; 1183 } 1184 } 1185 } 1186 1187 /* 1188 * If getattr is called on a vnode (e.g. a stat call), the filesystem 1189 * may call this routine to determine if the namecache has the hierarchical 1190 * change flag set, requiring the fsmid to be updated. 1191 * 1192 * Since 0 indicates no support, make sure the filesystem fsmid is at least 1193 * 1. 1194 */ 1195 int 1196 cache_check_fsmid_vp(struct vnode *vp, int64_t *fsmid) 1197 { 1198 struct namecache *ncp; 1199 int changed = 0; 1200 1201 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) { 1202 if (ncp->nc_flag & NCF_FSMID) { 1203 ncp->nc_flag &= ~NCF_FSMID; 1204 changed = 1; 1205 } 1206 } 1207 if (*fsmid == 0) 1208 ++*fsmid; 1209 if (changed) 1210 ++*fsmid; 1211 return(changed); 1212 } 1213 1214 /* 1215 * Obtain the FSMID for a vnode for filesystems which do not support 1216 * a built-in FSMID. 1217 */ 1218 int64_t 1219 cache_sync_fsmid_vp(struct vnode *vp) 1220 { 1221 struct namecache *ncp; 1222 1223 if ((ncp = TAILQ_FIRST(&vp->v_namecache)) != NULL) { 1224 if (ncp->nc_flag & NCF_FSMID) { 1225 ncp->nc_flag &= ~NCF_FSMID; 1226 ++ncp->nc_fsmid; 1227 } 1228 return(ncp->nc_fsmid); 1229 } 1230 return(VNOVAL); 1231 } 1232 1233 /* 1234 * Convert a directory vnode to a namecache record without any other 1235 * knowledge of the topology. This ONLY works with directory vnodes and 1236 * is ONLY used by the NFS server. dvp must be refd but unlocked, and the 1237 * returned ncp (if not NULL) will be held and unlocked. 1238 * 1239 * If 'makeit' is 0 and dvp has no existing namecache record, NULL is returned. 1240 * If 'makeit' is 1 we attempt to track-down and create the namecache topology 1241 * for dvp. This will fail only if the directory has been deleted out from 1242 * under the caller. 1243 * 1244 * Callers must always check for a NULL return no matter the value of 'makeit'. 1245 * 1246 * To avoid underflowing the kernel stack each recursive call increments 1247 * the makeit variable. 1248 */ 1249 1250 static int cache_inefficient_scan(struct nchandle *nch, struct ucred *cred, 1251 struct vnode *dvp); 1252 static int cache_fromdvp_try(struct vnode *dvp, struct ucred *cred, 1253 struct vnode **saved_dvp); 1254 1255 int 1256 cache_fromdvp(struct vnode *dvp, struct ucred *cred, int makeit, 1257 struct nchandle *nch) 1258 { 1259 struct vnode *saved_dvp; 1260 struct vnode *pvp; 1261 int error; 1262 1263 nch->ncp = NULL; 1264 nch->mount = dvp->v_mount; 1265 saved_dvp = NULL; 1266 1267 /* 1268 * Temporary debugging code to force the directory scanning code 1269 * to be exercised. 1270 */ 1271 if (ncvp_debug >= 3 && makeit && TAILQ_FIRST(&dvp->v_namecache)) { 1272 nch->ncp = TAILQ_FIRST(&dvp->v_namecache); 1273 kprintf("cache_fromdvp: forcing %s\n", nch->ncp->nc_name); 1274 goto force; 1275 } 1276 1277 /* 1278 * Loop until resolution, inside code will break out on error. 1279 */ 1280 while ((nch->ncp = TAILQ_FIRST(&dvp->v_namecache)) == NULL && makeit) { 1281 force: 1282 /* 1283 * If dvp is the root of its filesystem it should already 1284 * have a namecache pointer associated with it as a side 1285 * effect of the mount, but it may have been disassociated. 1286 */ 1287 if (dvp->v_flag & VROOT) { 1288 nch->ncp = _cache_get(nch->mount->mnt_ncmountpt.ncp); 1289 error = cache_resolve_mp(nch->mount); 1290 _cache_put(nch->ncp); 1291 if (ncvp_debug) { 1292 kprintf("cache_fromdvp: resolve root of mount %p error %d", 1293 dvp->v_mount, error); 1294 } 1295 if (error) { 1296 if (ncvp_debug) 1297 kprintf(" failed\n"); 1298 nch->ncp = NULL; 1299 break; 1300 } 1301 if (ncvp_debug) 1302 kprintf(" succeeded\n"); 1303 continue; 1304 } 1305 1306 /* 1307 * If we are recursed too deeply resort to an O(n^2) 1308 * algorithm to resolve the namecache topology. The 1309 * resolved pvp is left referenced in saved_dvp to 1310 * prevent the tree from being destroyed while we loop. 1311 */ 1312 if (makeit > 20) { 1313 error = cache_fromdvp_try(dvp, cred, &saved_dvp); 1314 if (error) { 1315 kprintf("lookupdotdot(longpath) failed %d " 1316 "dvp %p\n", error, dvp); 1317 break; 1318 } 1319 continue; 1320 } 1321 1322 /* 1323 * Get the parent directory and resolve its ncp. 1324 */ 1325 error = vop_nlookupdotdot(*dvp->v_ops, dvp, &pvp, cred); 1326 if (error) { 1327 kprintf("lookupdotdot failed %d dvp %p\n", error, dvp); 1328 break; 1329 } 1330 vn_unlock(pvp); 1331 1332 /* 1333 * Reuse makeit as a recursion depth counter. 1334 */ 1335 cache_fromdvp(pvp, cred, makeit + 1, nch); 1336 vrele(pvp); 1337 if (nch->ncp == NULL) 1338 break; 1339 1340 /* 1341 * Do an inefficient scan of pvp (embodied by ncp) to look 1342 * for dvp. This will create a namecache record for dvp on 1343 * success. We loop up to recheck on success. 1344 * 1345 * ncp and dvp are both held but not locked. 1346 */ 1347 error = cache_inefficient_scan(nch, cred, dvp); 1348 _cache_drop(nch->ncp); 1349 if (error) { 1350 kprintf("cache_fromdvp: scan %p (%s) failed on dvp=%p\n", 1351 pvp, nch->ncp->nc_name, dvp); 1352 nch->ncp = NULL; 1353 break; 1354 } 1355 if (ncvp_debug) { 1356 kprintf("cache_fromdvp: scan %p (%s) succeeded\n", 1357 pvp, nch->ncp->nc_name); 1358 } 1359 } 1360 1361 /* 1362 * hold it for real so the mount gets a ref 1363 */ 1364 if (nch->ncp) 1365 cache_hold(nch); 1366 if (saved_dvp) 1367 vrele(saved_dvp); 1368 if (nch->ncp) 1369 return (0); 1370 return (EINVAL); 1371 } 1372 1373 /* 1374 * Go up the chain of parent directories until we find something 1375 * we can resolve into the namecache. This is very inefficient. 1376 */ 1377 static 1378 int 1379 cache_fromdvp_try(struct vnode *dvp, struct ucred *cred, 1380 struct vnode **saved_dvp) 1381 { 1382 struct nchandle nch; 1383 struct vnode *pvp; 1384 int error; 1385 static time_t last_fromdvp_report; 1386 1387 /* 1388 * Loop getting the parent directory vnode until we get something we 1389 * can resolve in the namecache. 1390 */ 1391 vref(dvp); 1392 nch.mount = dvp->v_mount; 1393 1394 for (;;) { 1395 error = vop_nlookupdotdot(*dvp->v_ops, dvp, &pvp, cred); 1396 if (error) { 1397 vrele(dvp); 1398 return (error); 1399 } 1400 vn_unlock(pvp); 1401 if ((nch.ncp = TAILQ_FIRST(&pvp->v_namecache)) != NULL) { 1402 _cache_hold(nch.ncp); 1403 vrele(pvp); 1404 break; 1405 } 1406 if (pvp->v_flag & VROOT) { 1407 nch.ncp = _cache_get(pvp->v_mount->mnt_ncmountpt.ncp); 1408 error = cache_resolve_mp(nch.mount); 1409 _cache_unlock(nch.ncp); 1410 vrele(pvp); 1411 if (error) { 1412 _cache_drop(nch.ncp); 1413 vrele(dvp); 1414 return (error); 1415 } 1416 break; 1417 } 1418 vrele(dvp); 1419 dvp = pvp; 1420 } 1421 if (last_fromdvp_report != time_second) { 1422 last_fromdvp_report = time_second; 1423 kprintf("Warning: extremely inefficient path resolution on %s\n", 1424 nch.ncp->nc_name); 1425 } 1426 error = cache_inefficient_scan(&nch, cred, dvp); 1427 1428 /* 1429 * Hopefully dvp now has a namecache record associated with it. 1430 * Leave it referenced to prevent the kernel from recycling the 1431 * vnode. Otherwise extremely long directory paths could result 1432 * in endless recycling. 1433 */ 1434 if (*saved_dvp) 1435 vrele(*saved_dvp); 1436 *saved_dvp = dvp; 1437 return (error); 1438 } 1439 1440 1441 /* 1442 * Do an inefficient scan of the directory represented by ncp looking for 1443 * the directory vnode dvp. ncp must be held but not locked on entry and 1444 * will be held on return. dvp must be refd but not locked on entry and 1445 * will remain refd on return. 1446 * 1447 * Why do this at all? Well, due to its stateless nature the NFS server 1448 * converts file handles directly to vnodes without necessarily going through 1449 * the namecache ops that would otherwise create the namecache topology 1450 * leading to the vnode. We could either (1) Change the namecache algorithms 1451 * to allow disconnect namecache records that are re-merged opportunistically, 1452 * or (2) Make the NFS server backtrack and scan to recover a connected 1453 * namecache topology in order to then be able to issue new API lookups. 1454 * 1455 * It turns out that (1) is a huge mess. It takes a nice clean set of 1456 * namecache algorithms and introduces a lot of complication in every subsystem 1457 * that calls into the namecache to deal with the re-merge case, especially 1458 * since we are using the namecache to placehold negative lookups and the 1459 * vnode might not be immediately assigned. (2) is certainly far less 1460 * efficient then (1), but since we are only talking about directories here 1461 * (which are likely to remain cached), the case does not actually run all 1462 * that often and has the supreme advantage of not polluting the namecache 1463 * algorithms. 1464 */ 1465 static int 1466 cache_inefficient_scan(struct nchandle *nch, struct ucred *cred, 1467 struct vnode *dvp) 1468 { 1469 struct nlcomponent nlc; 1470 struct nchandle rncp; 1471 struct dirent *den; 1472 struct vnode *pvp; 1473 struct vattr vat; 1474 struct iovec iov; 1475 struct uio uio; 1476 int blksize; 1477 int eofflag; 1478 int bytes; 1479 char *rbuf; 1480 int error; 1481 1482 vat.va_blocksize = 0; 1483 if ((error = VOP_GETATTR(dvp, &vat)) != 0) 1484 return (error); 1485 if ((error = cache_vref(nch, cred, &pvp)) != 0) 1486 return (error); 1487 if (ncvp_debug) 1488 kprintf("inefficient_scan: directory iosize %ld vattr fileid = %lld\n", vat.va_blocksize, vat.va_fileid); 1489 if ((blksize = vat.va_blocksize) == 0) 1490 blksize = DEV_BSIZE; 1491 rbuf = kmalloc(blksize, M_TEMP, M_WAITOK); 1492 rncp.ncp = NULL; 1493 1494 eofflag = 0; 1495 uio.uio_offset = 0; 1496 again: 1497 iov.iov_base = rbuf; 1498 iov.iov_len = blksize; 1499 uio.uio_iov = &iov; 1500 uio.uio_iovcnt = 1; 1501 uio.uio_resid = blksize; 1502 uio.uio_segflg = UIO_SYSSPACE; 1503 uio.uio_rw = UIO_READ; 1504 uio.uio_td = curthread; 1505 1506 if (ncvp_debug >= 2) 1507 kprintf("cache_inefficient_scan: readdir @ %08x\n", (int)uio.uio_offset); 1508 error = VOP_READDIR(pvp, &uio, cred, &eofflag, NULL, NULL); 1509 if (error == 0) { 1510 den = (struct dirent *)rbuf; 1511 bytes = blksize - uio.uio_resid; 1512 1513 while (bytes > 0) { 1514 if (ncvp_debug >= 2) { 1515 kprintf("cache_inefficient_scan: %*.*s\n", 1516 den->d_namlen, den->d_namlen, 1517 den->d_name); 1518 } 1519 if (den->d_type != DT_WHT && 1520 den->d_ino == vat.va_fileid) { 1521 if (ncvp_debug) { 1522 kprintf("cache_inefficient_scan: " 1523 "MATCHED inode %lld path %s/%*.*s\n", 1524 vat.va_fileid, nch->ncp->nc_name, 1525 den->d_namlen, den->d_namlen, 1526 den->d_name); 1527 } 1528 nlc.nlc_nameptr = den->d_name; 1529 nlc.nlc_namelen = den->d_namlen; 1530 rncp = cache_nlookup(nch, &nlc); 1531 KKASSERT(rncp.ncp != NULL); 1532 break; 1533 } 1534 bytes -= _DIRENT_DIRSIZ(den); 1535 den = _DIRENT_NEXT(den); 1536 } 1537 if (rncp.ncp == NULL && eofflag == 0 && uio.uio_resid != blksize) 1538 goto again; 1539 } 1540 vrele(pvp); 1541 if (rncp.ncp) { 1542 if (rncp.ncp->nc_flag & NCF_UNRESOLVED) { 1543 _cache_setvp(rncp.ncp, dvp); 1544 if (ncvp_debug >= 2) { 1545 kprintf("cache_inefficient_scan: setvp %s/%s = %p\n", 1546 nch->ncp->nc_name, rncp.ncp->nc_name, dvp); 1547 } 1548 } else { 1549 if (ncvp_debug >= 2) { 1550 kprintf("cache_inefficient_scan: setvp %s/%s already set %p/%p\n", 1551 nch->ncp->nc_name, rncp.ncp->nc_name, dvp, 1552 rncp.ncp->nc_vp); 1553 } 1554 } 1555 if (rncp.ncp->nc_vp == NULL) 1556 error = rncp.ncp->nc_error; 1557 _cache_put(rncp.ncp); 1558 } else { 1559 kprintf("cache_inefficient_scan: dvp %p NOT FOUND in %s\n", 1560 dvp, nch->ncp->nc_name); 1561 error = ENOENT; 1562 } 1563 kfree(rbuf, M_TEMP); 1564 return (error); 1565 } 1566 1567 /* 1568 * Zap a namecache entry. The ncp is unconditionally set to an unresolved 1569 * state, which disassociates it from its vnode or ncneglist. 1570 * 1571 * Then, if there are no additional references to the ncp and no children, 1572 * the ncp is removed from the topology and destroyed. This function will 1573 * also run through the nc_parent chain and destroy parent ncps if possible. 1574 * As a side benefit, it turns out the only conditions that allow running 1575 * up the chain are also the conditions to ensure no deadlock will occur. 1576 * 1577 * References and/or children may exist if the ncp is in the middle of the 1578 * topology, preventing the ncp from being destroyed. 1579 * 1580 * This function must be called with the ncp held and locked and will unlock 1581 * and drop it during zapping. 1582 */ 1583 static void 1584 cache_zap(struct namecache *ncp) 1585 { 1586 struct namecache *par; 1587 1588 /* 1589 * Disassociate the vnode or negative cache ref and set NCF_UNRESOLVED. 1590 */ 1591 _cache_setunresolved(ncp); 1592 1593 /* 1594 * Try to scrap the entry and possibly tail-recurse on its parent. 1595 * We only scrap unref'd (other then our ref) unresolved entries, 1596 * we do not scrap 'live' entries. 1597 */ 1598 while (ncp->nc_flag & NCF_UNRESOLVED) { 1599 /* 1600 * Someone other then us has a ref, stop. 1601 */ 1602 if (ncp->nc_refs > 1) 1603 goto done; 1604 1605 /* 1606 * We have children, stop. 1607 */ 1608 if (!TAILQ_EMPTY(&ncp->nc_list)) 1609 goto done; 1610 1611 /* 1612 * Remove ncp from the topology: hash table and parent linkage. 1613 */ 1614 if (ncp->nc_flag & NCF_HASHED) { 1615 ncp->nc_flag &= ~NCF_HASHED; 1616 LIST_REMOVE(ncp, nc_hash); 1617 } 1618 if ((par = ncp->nc_parent) != NULL) { 1619 par = _cache_hold(par); 1620 TAILQ_REMOVE(&par->nc_list, ncp, nc_entry); 1621 ncp->nc_parent = NULL; 1622 if (par->nc_vp && TAILQ_EMPTY(&par->nc_list)) 1623 vdrop(par->nc_vp); 1624 } 1625 1626 /* 1627 * ncp should not have picked up any refs. Physically 1628 * destroy the ncp. 1629 */ 1630 KKASSERT(ncp->nc_refs == 1); 1631 --numunres; 1632 /* _cache_unlock(ncp) not required */ 1633 ncp->nc_refs = -1; /* safety */ 1634 if (ncp->nc_name) 1635 kfree(ncp->nc_name, M_VFSCACHE); 1636 kfree(ncp, M_VFSCACHE); 1637 1638 /* 1639 * Loop on the parent (it may be NULL). Only bother looping 1640 * if the parent has a single ref (ours), which also means 1641 * we can lock it trivially. 1642 */ 1643 ncp = par; 1644 if (ncp == NULL) 1645 return; 1646 if (ncp->nc_refs != 1) { 1647 _cache_drop(ncp); 1648 return; 1649 } 1650 KKASSERT(par->nc_exlocks == 0); 1651 _cache_lock(ncp); 1652 } 1653 done: 1654 _cache_unlock(ncp); 1655 atomic_subtract_int(&ncp->nc_refs, 1); 1656 } 1657 1658 static enum { CHI_LOW, CHI_HIGH } cache_hysteresis_state = CHI_LOW; 1659 1660 static __inline 1661 void 1662 cache_hysteresis(void) 1663 { 1664 /* 1665 * Don't cache too many negative hits. We use hysteresis to reduce 1666 * the impact on the critical path. 1667 */ 1668 switch(cache_hysteresis_state) { 1669 case CHI_LOW: 1670 if (numneg > MINNEG && numneg * ncnegfactor > numcache) { 1671 cache_cleanneg(10); 1672 cache_hysteresis_state = CHI_HIGH; 1673 } 1674 break; 1675 case CHI_HIGH: 1676 if (numneg > MINNEG * 9 / 10 && 1677 numneg * ncnegfactor * 9 / 10 > numcache 1678 ) { 1679 cache_cleanneg(10); 1680 } else { 1681 cache_hysteresis_state = CHI_LOW; 1682 } 1683 break; 1684 } 1685 } 1686 1687 /* 1688 * NEW NAMECACHE LOOKUP API 1689 * 1690 * Lookup an entry in the cache. A locked, referenced, non-NULL 1691 * entry is *always* returned, even if the supplied component is illegal. 1692 * The resulting namecache entry should be returned to the system with 1693 * cache_put() or _cache_unlock() + cache_drop(). 1694 * 1695 * namecache locks are recursive but care must be taken to avoid lock order 1696 * reversals. 1697 * 1698 * Nobody else will be able to manipulate the associated namespace (e.g. 1699 * create, delete, rename, rename-target) until the caller unlocks the 1700 * entry. 1701 * 1702 * The returned entry will be in one of three states: positive hit (non-null 1703 * vnode), negative hit (null vnode), or unresolved (NCF_UNRESOLVED is set). 1704 * Unresolved entries must be resolved through the filesystem to associate the 1705 * vnode and/or determine whether a positive or negative hit has occured. 1706 * 1707 * It is not necessary to lock a directory in order to lock namespace under 1708 * that directory. In fact, it is explicitly not allowed to do that. A 1709 * directory is typically only locked when being created, renamed, or 1710 * destroyed. 1711 * 1712 * The directory (par) may be unresolved, in which case any returned child 1713 * will likely also be marked unresolved. Likely but not guarenteed. Since 1714 * the filesystem lookup requires a resolved directory vnode the caller is 1715 * responsible for resolving the namecache chain top-down. This API 1716 * specifically allows whole chains to be created in an unresolved state. 1717 */ 1718 struct nchandle 1719 cache_nlookup(struct nchandle *par_nch, struct nlcomponent *nlc) 1720 { 1721 struct nchandle nch; 1722 struct namecache *ncp; 1723 struct namecache *new_ncp; 1724 struct nchashhead *nchpp; 1725 u_int32_t hash; 1726 globaldata_t gd; 1727 1728 numcalls++; 1729 gd = mycpu; 1730 1731 /* 1732 * Try to locate an existing entry 1733 */ 1734 hash = fnv_32_buf(nlc->nlc_nameptr, nlc->nlc_namelen, FNV1_32_INIT); 1735 hash = fnv_32_buf(&par_nch->ncp, sizeof(par_nch->ncp), hash); 1736 new_ncp = NULL; 1737 restart: 1738 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 1739 numchecks++; 1740 1741 /* 1742 * Try to zap entries that have timed out. We have 1743 * to be careful here because locked leafs may depend 1744 * on the vnode remaining intact in a parent, so only 1745 * do this under very specific conditions. 1746 */ 1747 if (ncp->nc_timeout && 1748 (int)(ncp->nc_timeout - ticks) < 0 && 1749 (ncp->nc_flag & NCF_UNRESOLVED) == 0 && 1750 ncp->nc_exlocks == 0 && 1751 TAILQ_EMPTY(&ncp->nc_list) 1752 ) { 1753 cache_zap(_cache_get(ncp)); 1754 goto restart; 1755 } 1756 1757 /* 1758 * Break out if we find a matching entry. Note that 1759 * UNRESOLVED entries may match, but DESTROYED entries 1760 * do not. 1761 */ 1762 if (ncp->nc_parent == par_nch->ncp && 1763 ncp->nc_nlen == nlc->nlc_namelen && 1764 bcmp(ncp->nc_name, nlc->nlc_nameptr, ncp->nc_nlen) == 0 && 1765 (ncp->nc_flag & NCF_DESTROYED) == 0 1766 ) { 1767 if (_cache_get_nonblock(ncp) == 0) { 1768 if (new_ncp) 1769 _cache_free(new_ncp); 1770 goto found; 1771 } 1772 _cache_get(ncp); 1773 _cache_put(ncp); 1774 goto restart; 1775 } 1776 } 1777 1778 /* 1779 * We failed to locate an entry, create a new entry and add it to 1780 * the cache. We have to relookup after possibly blocking in 1781 * malloc. 1782 */ 1783 if (new_ncp == NULL) { 1784 new_ncp = cache_alloc(nlc->nlc_namelen); 1785 goto restart; 1786 } 1787 1788 ncp = new_ncp; 1789 1790 /* 1791 * Initialize as a new UNRESOLVED entry, lock (non-blocking), 1792 * and link to the parent. The mount point is usually inherited 1793 * from the parent unless this is a special case such as a mount 1794 * point where nlc_namelen is 0. If nlc_namelen is 0 nc_name will 1795 * be NULL. 1796 */ 1797 if (nlc->nlc_namelen) { 1798 bcopy(nlc->nlc_nameptr, ncp->nc_name, nlc->nlc_namelen); 1799 ncp->nc_name[nlc->nlc_namelen] = 0; 1800 } 1801 nchpp = NCHHASH(hash); 1802 LIST_INSERT_HEAD(nchpp, ncp, nc_hash); 1803 ncp->nc_flag |= NCF_HASHED; 1804 cache_link_parent(ncp, par_nch->ncp); 1805 found: 1806 /* 1807 * stats and namecache size management 1808 */ 1809 if (ncp->nc_flag & NCF_UNRESOLVED) 1810 ++gd->gd_nchstats->ncs_miss; 1811 else if (ncp->nc_vp) 1812 ++gd->gd_nchstats->ncs_goodhits; 1813 else 1814 ++gd->gd_nchstats->ncs_neghits; 1815 cache_hysteresis(); 1816 nch.mount = par_nch->mount; 1817 nch.ncp = ncp; 1818 ++nch.mount->mnt_refs; 1819 return(nch); 1820 } 1821 1822 /* 1823 * The namecache entry is marked as being used as a mount point. 1824 * Locate the mount if it is visible to the caller. 1825 */ 1826 struct findmount_info { 1827 struct mount *result; 1828 struct mount *nch_mount; 1829 struct namecache *nch_ncp; 1830 }; 1831 1832 static 1833 int 1834 cache_findmount_callback(struct mount *mp, void *data) 1835 { 1836 struct findmount_info *info = data; 1837 1838 /* 1839 * Check the mount's mounted-on point against the passed nch. 1840 */ 1841 if (mp->mnt_ncmounton.mount == info->nch_mount && 1842 mp->mnt_ncmounton.ncp == info->nch_ncp 1843 ) { 1844 info->result = mp; 1845 return(-1); 1846 } 1847 return(0); 1848 } 1849 1850 struct mount * 1851 cache_findmount(struct nchandle *nch) 1852 { 1853 struct findmount_info info; 1854 1855 info.result = NULL; 1856 info.nch_mount = nch->mount; 1857 info.nch_ncp = nch->ncp; 1858 mountlist_scan(cache_findmount_callback, &info, 1859 MNTSCAN_FORWARD|MNTSCAN_NOBUSY); 1860 return(info.result); 1861 } 1862 1863 /* 1864 * Resolve an unresolved namecache entry, generally by looking it up. 1865 * The passed ncp must be locked and refd. 1866 * 1867 * Theoretically since a vnode cannot be recycled while held, and since 1868 * the nc_parent chain holds its vnode as long as children exist, the 1869 * direct parent of the cache entry we are trying to resolve should 1870 * have a valid vnode. If not then generate an error that we can 1871 * determine is related to a resolver bug. 1872 * 1873 * However, if a vnode was in the middle of a recyclement when the NCP 1874 * got locked, ncp->nc_vp might point to a vnode that is about to become 1875 * invalid. cache_resolve() handles this case by unresolving the entry 1876 * and then re-resolving it. 1877 * 1878 * Note that successful resolution does not necessarily return an error 1879 * code of 0. If the ncp resolves to a negative cache hit then ENOENT 1880 * will be returned. 1881 */ 1882 int 1883 cache_resolve(struct nchandle *nch, struct ucred *cred) 1884 { 1885 struct namecache *par; 1886 struct namecache *ncp; 1887 struct nchandle nctmp; 1888 struct mount *mp; 1889 struct vnode *dvp; 1890 int error; 1891 1892 ncp = nch->ncp; 1893 mp = nch->mount; 1894 restart: 1895 /* 1896 * If the ncp is already resolved we have nothing to do. However, 1897 * we do want to guarentee that a usable vnode is returned when 1898 * a vnode is present, so make sure it hasn't been reclaimed. 1899 */ 1900 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) { 1901 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) 1902 _cache_setunresolved(ncp); 1903 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) 1904 return (ncp->nc_error); 1905 } 1906 1907 /* 1908 * Mount points need special handling because the parent does not 1909 * belong to the same filesystem as the ncp. 1910 */ 1911 if (ncp == mp->mnt_ncmountpt.ncp) 1912 return (cache_resolve_mp(mp)); 1913 1914 /* 1915 * We expect an unbroken chain of ncps to at least the mount point, 1916 * and even all the way to root (but this code doesn't have to go 1917 * past the mount point). 1918 */ 1919 if (ncp->nc_parent == NULL) { 1920 kprintf("EXDEV case 1 %p %*.*s\n", ncp, 1921 ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name); 1922 ncp->nc_error = EXDEV; 1923 return(ncp->nc_error); 1924 } 1925 1926 /* 1927 * The vp's of the parent directories in the chain are held via vhold() 1928 * due to the existance of the child, and should not disappear. 1929 * However, there are cases where they can disappear: 1930 * 1931 * - due to filesystem I/O errors. 1932 * - due to NFS being stupid about tracking the namespace and 1933 * destroys the namespace for entire directories quite often. 1934 * - due to forced unmounts. 1935 * - due to an rmdir (parent will be marked DESTROYED) 1936 * 1937 * When this occurs we have to track the chain backwards and resolve 1938 * it, looping until the resolver catches up to the current node. We 1939 * could recurse here but we might run ourselves out of kernel stack 1940 * so we do it in a more painful manner. This situation really should 1941 * not occur all that often, or if it does not have to go back too 1942 * many nodes to resolve the ncp. 1943 */ 1944 while (ncp->nc_parent->nc_vp == NULL) { 1945 /* 1946 * This case can occur if a process is CD'd into a 1947 * directory which is then rmdir'd. If the parent is marked 1948 * destroyed there is no point trying to resolve it. 1949 */ 1950 if (ncp->nc_parent->nc_flag & NCF_DESTROYED) 1951 return(ENOENT); 1952 1953 par = ncp->nc_parent; 1954 while (par->nc_parent && par->nc_parent->nc_vp == NULL) 1955 par = par->nc_parent; 1956 if (par->nc_parent == NULL) { 1957 kprintf("EXDEV case 2 %*.*s\n", 1958 par->nc_nlen, par->nc_nlen, par->nc_name); 1959 return (EXDEV); 1960 } 1961 kprintf("[diagnostic] cache_resolve: had to recurse on %*.*s\n", 1962 par->nc_nlen, par->nc_nlen, par->nc_name); 1963 /* 1964 * The parent is not set in stone, ref and lock it to prevent 1965 * it from disappearing. Also note that due to renames it 1966 * is possible for our ncp to move and for par to no longer 1967 * be one of its parents. We resolve it anyway, the loop 1968 * will handle any moves. 1969 */ 1970 _cache_get(par); 1971 if (par == nch->mount->mnt_ncmountpt.ncp) { 1972 cache_resolve_mp(nch->mount); 1973 } else if ((dvp = par->nc_parent->nc_vp) == NULL) { 1974 kprintf("[diagnostic] cache_resolve: raced on %*.*s\n", par->nc_nlen, par->nc_nlen, par->nc_name); 1975 _cache_put(par); 1976 continue; 1977 } else if (par->nc_flag & NCF_UNRESOLVED) { 1978 /* vhold(dvp); - DVP can't go away */ 1979 nctmp.mount = mp; 1980 nctmp.ncp = par; 1981 par->nc_error = VOP_NRESOLVE(&nctmp, dvp, cred); 1982 /* vdrop(dvp); */ 1983 } 1984 if ((error = par->nc_error) != 0) { 1985 if (par->nc_error != EAGAIN) { 1986 kprintf("EXDEV case 3 %*.*s error %d\n", 1987 par->nc_nlen, par->nc_nlen, par->nc_name, 1988 par->nc_error); 1989 _cache_put(par); 1990 return(error); 1991 } 1992 kprintf("[diagnostic] cache_resolve: EAGAIN par %p %*.*s\n", 1993 par, par->nc_nlen, par->nc_nlen, par->nc_name); 1994 } 1995 _cache_put(par); 1996 /* loop */ 1997 } 1998 1999 /* 2000 * Call VOP_NRESOLVE() to get the vp, then scan for any disconnected 2001 * ncp's and reattach them. If this occurs the original ncp is marked 2002 * EAGAIN to force a relookup. 2003 * 2004 * NOTE: in order to call VOP_NRESOLVE(), the parent of the passed 2005 * ncp must already be resolved. 2006 */ 2007 dvp = ncp->nc_parent->nc_vp; 2008 /* vhold(dvp); - dvp can't go away */ 2009 nctmp.mount = mp; 2010 nctmp.ncp = ncp; 2011 ncp->nc_error = VOP_NRESOLVE(&nctmp, dvp, cred); 2012 /* vdrop(dvp); */ 2013 if (ncp->nc_error == EAGAIN) { 2014 kprintf("[diagnostic] cache_resolve: EAGAIN ncp %p %*.*s\n", 2015 ncp, ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name); 2016 goto restart; 2017 } 2018 return(ncp->nc_error); 2019 } 2020 2021 /* 2022 * Resolve the ncp associated with a mount point. Such ncp's almost always 2023 * remain resolved and this routine is rarely called. NFS MPs tends to force 2024 * re-resolution more often due to its mac-truck-smash-the-namecache 2025 * method of tracking namespace changes. 2026 * 2027 * The semantics for this call is that the passed ncp must be locked on 2028 * entry and will be locked on return. However, if we actually have to 2029 * resolve the mount point we temporarily unlock the entry in order to 2030 * avoid race-to-root deadlocks due to e.g. dead NFS mounts. Because of 2031 * the unlock we have to recheck the flags after we relock. 2032 */ 2033 static int 2034 cache_resolve_mp(struct mount *mp) 2035 { 2036 struct namecache *ncp = mp->mnt_ncmountpt.ncp; 2037 struct vnode *vp; 2038 int error; 2039 2040 KKASSERT(mp != NULL); 2041 2042 /* 2043 * If the ncp is already resolved we have nothing to do. However, 2044 * we do want to guarentee that a usable vnode is returned when 2045 * a vnode is present, so make sure it hasn't been reclaimed. 2046 */ 2047 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) { 2048 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) 2049 _cache_setunresolved(ncp); 2050 } 2051 2052 if (ncp->nc_flag & NCF_UNRESOLVED) { 2053 _cache_unlock(ncp); 2054 while (vfs_busy(mp, 0)) 2055 ; 2056 error = VFS_ROOT(mp, &vp); 2057 _cache_lock(ncp); 2058 2059 /* 2060 * recheck the ncp state after relocking. 2061 */ 2062 if (ncp->nc_flag & NCF_UNRESOLVED) { 2063 ncp->nc_error = error; 2064 if (error == 0) { 2065 _cache_setvp(ncp, vp); 2066 vput(vp); 2067 } else { 2068 kprintf("[diagnostic] cache_resolve_mp: failed to resolve mount %p\n", mp); 2069 _cache_setvp(ncp, NULL); 2070 } 2071 } else if (error == 0) { 2072 vput(vp); 2073 } 2074 vfs_unbusy(mp); 2075 } 2076 return(ncp->nc_error); 2077 } 2078 2079 void 2080 cache_cleanneg(int count) 2081 { 2082 struct namecache *ncp; 2083 2084 /* 2085 * Automode from the vnlru proc - clean out 10% of the negative cache 2086 * entries. 2087 */ 2088 if (count == 0) 2089 count = numneg / 10 + 1; 2090 2091 /* 2092 * Attempt to clean out the specified number of negative cache 2093 * entries. 2094 */ 2095 while (count) { 2096 ncp = TAILQ_FIRST(&ncneglist); 2097 if (ncp == NULL) { 2098 KKASSERT(numneg == 0); 2099 break; 2100 } 2101 TAILQ_REMOVE(&ncneglist, ncp, nc_vnode); 2102 TAILQ_INSERT_TAIL(&ncneglist, ncp, nc_vnode); 2103 if (_cache_get_nonblock(ncp) == 0) 2104 cache_zap(ncp); 2105 --count; 2106 } 2107 } 2108 2109 /* 2110 * Rehash a ncp. Rehashing is typically required if the name changes (should 2111 * not generally occur) or the parent link changes. This function will 2112 * unhash the ncp if the ncp is no longer hashable. 2113 */ 2114 static void 2115 _cache_rehash(struct namecache *ncp) 2116 { 2117 struct nchashhead *nchpp; 2118 u_int32_t hash; 2119 2120 if (ncp->nc_flag & NCF_HASHED) { 2121 ncp->nc_flag &= ~NCF_HASHED; 2122 LIST_REMOVE(ncp, nc_hash); 2123 } 2124 if (ncp->nc_nlen && ncp->nc_parent) { 2125 hash = fnv_32_buf(ncp->nc_name, ncp->nc_nlen, FNV1_32_INIT); 2126 hash = fnv_32_buf(&ncp->nc_parent, 2127 sizeof(ncp->nc_parent), hash); 2128 nchpp = NCHHASH(hash); 2129 LIST_INSERT_HEAD(nchpp, ncp, nc_hash); 2130 ncp->nc_flag |= NCF_HASHED; 2131 } 2132 } 2133 2134 /* 2135 * Name cache initialization, from vfsinit() when we are booting 2136 */ 2137 void 2138 nchinit(void) 2139 { 2140 int i; 2141 globaldata_t gd; 2142 2143 /* initialise per-cpu namecache effectiveness statistics. */ 2144 for (i = 0; i < ncpus; ++i) { 2145 gd = globaldata_find(i); 2146 gd->gd_nchstats = &nchstats[i]; 2147 } 2148 TAILQ_INIT(&ncneglist); 2149 nchashtbl = hashinit(desiredvnodes*2, M_VFSCACHE, &nchash); 2150 nclockwarn = 1 * hz; 2151 } 2152 2153 /* 2154 * Called from start_init() to bootstrap the root filesystem. Returns 2155 * a referenced, unlocked namecache record. 2156 */ 2157 void 2158 cache_allocroot(struct nchandle *nch, struct mount *mp, struct vnode *vp) 2159 { 2160 nch->ncp = cache_alloc(0); 2161 nch->mount = mp; 2162 ++mp->mnt_refs; 2163 if (vp) 2164 _cache_setvp(nch->ncp, vp); 2165 } 2166 2167 /* 2168 * vfs_cache_setroot() 2169 * 2170 * Create an association between the root of our namecache and 2171 * the root vnode. This routine may be called several times during 2172 * booting. 2173 * 2174 * If the caller intends to save the returned namecache pointer somewhere 2175 * it must cache_hold() it. 2176 */ 2177 void 2178 vfs_cache_setroot(struct vnode *nvp, struct nchandle *nch) 2179 { 2180 struct vnode *ovp; 2181 struct nchandle onch; 2182 2183 ovp = rootvnode; 2184 onch = rootnch; 2185 rootvnode = nvp; 2186 if (nch) 2187 rootnch = *nch; 2188 else 2189 cache_zero(&rootnch); 2190 if (ovp) 2191 vrele(ovp); 2192 if (onch.ncp) 2193 cache_drop(&onch); 2194 } 2195 2196 /* 2197 * XXX OLD API COMPAT FUNCTION. This really messes up the new namecache 2198 * topology and is being removed as quickly as possible. The new VOP_N*() 2199 * API calls are required to make specific adjustments using the supplied 2200 * ncp pointers rather then just bogusly purging random vnodes. 2201 * 2202 * Invalidate all namecache entries to a particular vnode as well as 2203 * any direct children of that vnode in the namecache. This is a 2204 * 'catch all' purge used by filesystems that do not know any better. 2205 * 2206 * Note that the linkage between the vnode and its namecache entries will 2207 * be removed, but the namecache entries themselves might stay put due to 2208 * active references from elsewhere in the system or due to the existance of 2209 * the children. The namecache topology is left intact even if we do not 2210 * know what the vnode association is. Such entries will be marked 2211 * NCF_UNRESOLVED. 2212 */ 2213 void 2214 cache_purge(struct vnode *vp) 2215 { 2216 cache_inval_vp(vp, CINV_DESTROY | CINV_CHILDREN); 2217 } 2218 2219 /* 2220 * Flush all entries referencing a particular filesystem. 2221 * 2222 * Since we need to check it anyway, we will flush all the invalid 2223 * entries at the same time. 2224 */ 2225 #if 0 2226 2227 void 2228 cache_purgevfs(struct mount *mp) 2229 { 2230 struct nchashhead *nchpp; 2231 struct namecache *ncp, *nnp; 2232 2233 /* 2234 * Scan hash tables for applicable entries. 2235 */ 2236 for (nchpp = &nchashtbl[nchash]; nchpp >= nchashtbl; nchpp--) { 2237 ncp = LIST_FIRST(nchpp); 2238 if (ncp) 2239 _cache_hold(ncp); 2240 while (ncp) { 2241 nnp = LIST_NEXT(ncp, nc_hash); 2242 if (nnp) 2243 _cache_hold(nnp); 2244 if (ncp->nc_mount == mp) { 2245 _cache_lock(ncp); 2246 cache_zap(ncp); 2247 } else { 2248 _cache_drop(ncp); 2249 } 2250 ncp = nnp; 2251 } 2252 } 2253 } 2254 2255 #endif 2256 2257 /* 2258 * Create a new (theoretically) unique fsmid 2259 */ 2260 int64_t 2261 cache_getnewfsmid(void) 2262 { 2263 static int fsmid_roller; 2264 int64_t fsmid; 2265 2266 ++fsmid_roller; 2267 fsmid = ((int64_t)time_second << 32) | 2268 (fsmid_roller & 0x7FFFFFFF); 2269 return (fsmid); 2270 } 2271 2272 2273 static int disablecwd; 2274 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, ""); 2275 2276 static u_long numcwdcalls; STATNODE(CTLFLAG_RD, numcwdcalls, &numcwdcalls); 2277 static u_long numcwdfail1; STATNODE(CTLFLAG_RD, numcwdfail1, &numcwdfail1); 2278 static u_long numcwdfail2; STATNODE(CTLFLAG_RD, numcwdfail2, &numcwdfail2); 2279 static u_long numcwdfail3; STATNODE(CTLFLAG_RD, numcwdfail3, &numcwdfail3); 2280 static u_long numcwdfail4; STATNODE(CTLFLAG_RD, numcwdfail4, &numcwdfail4); 2281 static u_long numcwdfound; STATNODE(CTLFLAG_RD, numcwdfound, &numcwdfound); 2282 2283 int 2284 sys___getcwd(struct __getcwd_args *uap) 2285 { 2286 int buflen; 2287 int error; 2288 char *buf; 2289 char *bp; 2290 2291 if (disablecwd) 2292 return (ENODEV); 2293 2294 buflen = uap->buflen; 2295 if (buflen < 2) 2296 return (EINVAL); 2297 if (buflen > MAXPATHLEN) 2298 buflen = MAXPATHLEN; 2299 2300 buf = kmalloc(buflen, M_TEMP, M_WAITOK); 2301 bp = kern_getcwd(buf, buflen, &error); 2302 if (error == 0) 2303 error = copyout(bp, uap->buf, strlen(bp) + 1); 2304 kfree(buf, M_TEMP); 2305 return (error); 2306 } 2307 2308 char * 2309 kern_getcwd(char *buf, size_t buflen, int *error) 2310 { 2311 struct proc *p = curproc; 2312 char *bp; 2313 int i, slash_prefixed; 2314 struct filedesc *fdp; 2315 struct nchandle nch; 2316 2317 numcwdcalls++; 2318 bp = buf; 2319 bp += buflen - 1; 2320 *bp = '\0'; 2321 fdp = p->p_fd; 2322 slash_prefixed = 0; 2323 2324 nch = fdp->fd_ncdir; 2325 while (nch.ncp && (nch.ncp != fdp->fd_nrdir.ncp || 2326 nch.mount != fdp->fd_nrdir.mount) 2327 ) { 2328 /* 2329 * While traversing upwards if we encounter the root 2330 * of the current mount we have to skip to the mount point 2331 * in the underlying filesystem. 2332 */ 2333 if (nch.ncp == nch.mount->mnt_ncmountpt.ncp) { 2334 nch = nch.mount->mnt_ncmounton; 2335 continue; 2336 } 2337 2338 /* 2339 * Prepend the path segment 2340 */ 2341 for (i = nch.ncp->nc_nlen - 1; i >= 0; i--) { 2342 if (bp == buf) { 2343 numcwdfail4++; 2344 *error = ENOMEM; 2345 return(NULL); 2346 } 2347 *--bp = nch.ncp->nc_name[i]; 2348 } 2349 if (bp == buf) { 2350 numcwdfail4++; 2351 *error = ENOMEM; 2352 return(NULL); 2353 } 2354 *--bp = '/'; 2355 slash_prefixed = 1; 2356 2357 /* 2358 * Go up a directory. This isn't a mount point so we don't 2359 * have to check again. 2360 */ 2361 nch.ncp = nch.ncp->nc_parent; 2362 } 2363 if (nch.ncp == NULL) { 2364 numcwdfail2++; 2365 *error = ENOENT; 2366 return(NULL); 2367 } 2368 if (!slash_prefixed) { 2369 if (bp == buf) { 2370 numcwdfail4++; 2371 *error = ENOMEM; 2372 return(NULL); 2373 } 2374 *--bp = '/'; 2375 } 2376 numcwdfound++; 2377 *error = 0; 2378 return (bp); 2379 } 2380 2381 /* 2382 * Thus begins the fullpath magic. 2383 */ 2384 2385 #undef STATNODE 2386 #define STATNODE(name) \ 2387 static u_int name; \ 2388 SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, "") 2389 2390 static int disablefullpath; 2391 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, 2392 &disablefullpath, 0, ""); 2393 2394 STATNODE(numfullpathcalls); 2395 STATNODE(numfullpathfail1); 2396 STATNODE(numfullpathfail2); 2397 STATNODE(numfullpathfail3); 2398 STATNODE(numfullpathfail4); 2399 STATNODE(numfullpathfound); 2400 2401 int 2402 cache_fullpath(struct proc *p, struct nchandle *nchp, char **retbuf, char **freebuf) 2403 { 2404 char *bp, *buf; 2405 int i, slash_prefixed; 2406 struct nchandle fd_nrdir; 2407 struct nchandle nch; 2408 2409 numfullpathcalls--; 2410 2411 *retbuf = NULL; 2412 *freebuf = NULL; 2413 2414 buf = kmalloc(MAXPATHLEN, M_TEMP, M_WAITOK); 2415 bp = buf + MAXPATHLEN - 1; 2416 *bp = '\0'; 2417 if (p != NULL) 2418 fd_nrdir = p->p_fd->fd_nrdir; 2419 else 2420 fd_nrdir = rootnch; 2421 slash_prefixed = 0; 2422 nch = *nchp; 2423 2424 while (nch.ncp && 2425 (nch.ncp != fd_nrdir.ncp || nch.mount != fd_nrdir.mount) 2426 ) { 2427 /* 2428 * While traversing upwards if we encounter the root 2429 * of the current mount we have to skip to the mount point. 2430 */ 2431 if (nch.ncp == nch.mount->mnt_ncmountpt.ncp) { 2432 nch = nch.mount->mnt_ncmounton; 2433 continue; 2434 } 2435 2436 /* 2437 * Prepend the path segment 2438 */ 2439 for (i = nch.ncp->nc_nlen - 1; i >= 0; i--) { 2440 if (bp == buf) { 2441 numfullpathfail4++; 2442 kfree(buf, M_TEMP); 2443 return(ENOMEM); 2444 } 2445 *--bp = nch.ncp->nc_name[i]; 2446 } 2447 if (bp == buf) { 2448 numfullpathfail4++; 2449 kfree(buf, M_TEMP); 2450 return(ENOMEM); 2451 } 2452 *--bp = '/'; 2453 slash_prefixed = 1; 2454 2455 /* 2456 * Go up a directory. This isn't a mount point so we don't 2457 * have to check again. 2458 */ 2459 nch.ncp = nch.ncp->nc_parent; 2460 } 2461 if (nch.ncp == NULL) { 2462 numfullpathfail2++; 2463 kfree(buf, M_TEMP); 2464 return(ENOENT); 2465 } 2466 2467 if (!slash_prefixed) { 2468 if (bp == buf) { 2469 numfullpathfail4++; 2470 kfree(buf, M_TEMP); 2471 return(ENOMEM); 2472 } 2473 *--bp = '/'; 2474 } 2475 numfullpathfound++; 2476 *retbuf = bp; 2477 *freebuf = buf; 2478 2479 return(0); 2480 } 2481 2482 int 2483 vn_fullpath(struct proc *p, struct vnode *vn, char **retbuf, char **freebuf) 2484 { 2485 struct namecache *ncp; 2486 struct nchandle nch; 2487 2488 numfullpathcalls++; 2489 if (disablefullpath) 2490 return (ENODEV); 2491 2492 if (p == NULL) 2493 return (EINVAL); 2494 2495 /* vn is NULL, client wants us to use p->p_textvp */ 2496 if (vn == NULL) { 2497 if ((vn = p->p_textvp) == NULL) 2498 return (EINVAL); 2499 } 2500 TAILQ_FOREACH(ncp, &vn->v_namecache, nc_vnode) { 2501 if (ncp->nc_nlen) 2502 break; 2503 } 2504 if (ncp == NULL) 2505 return (EINVAL); 2506 2507 numfullpathcalls--; 2508 nch.ncp = ncp;; 2509 nch.mount = vn->v_mount; 2510 return(cache_fullpath(p, &nch, retbuf, freebuf)); 2511 } 2512