1 /* 2 * Copyright (c) 2003,2004,2009 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 69 #include <sys/param.h> 70 #include <sys/systm.h> 71 #include <sys/kernel.h> 72 #include <sys/sysctl.h> 73 #include <sys/mount.h> 74 #include <sys/vnode.h> 75 #include <sys/malloc.h> 76 #include <sys/sysproto.h> 77 #include <sys/spinlock.h> 78 #include <sys/proc.h> 79 #include <sys/namei.h> 80 #include <sys/nlookup.h> 81 #include <sys/filedesc.h> 82 #include <sys/fnv_hash.h> 83 #include <sys/globaldata.h> 84 #include <sys/kern_syscall.h> 85 #include <sys/dirent.h> 86 #include <ddb/ddb.h> 87 88 #include <sys/sysref2.h> 89 #include <sys/spinlock2.h> 90 #include <sys/mplock2.h> 91 92 #define MAX_RECURSION_DEPTH 64 93 94 /* 95 * Random lookups in the cache are accomplished with a hash table using 96 * a hash key of (nc_src_vp, name). Each hash chain has its own spin lock. 97 * 98 * Negative entries may exist and correspond to resolved namecache 99 * structures where nc_vp is NULL. In a negative entry, NCF_WHITEOUT 100 * will be set if the entry corresponds to a whited-out directory entry 101 * (verses simply not finding the entry at all). ncneglist is locked 102 * with a global spinlock (ncspin). 103 * 104 * MPSAFE RULES: 105 * 106 * (1) A ncp must be referenced before it can be locked. 107 * 108 * (2) A ncp must be locked in order to modify it. 109 * 110 * (3) ncp locks are always ordered child -> parent. That may seem 111 * backwards but forward scans use the hash table and thus can hold 112 * the parent unlocked when traversing downward. 113 * 114 * This allows insert/rename/delete/dot-dot and other operations 115 * to use ncp->nc_parent links. 116 * 117 * This also prevents a locked up e.g. NFS node from creating a 118 * chain reaction all the way back to the root vnode / namecache. 119 * 120 * (4) parent linkages require both the parent and child to be locked. 121 */ 122 123 /* 124 * Structures associated with name cacheing. 125 */ 126 #define NCHHASH(hash) (&nchashtbl[(hash) & nchash]) 127 #define MINNEG 1024 128 129 MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); 130 131 LIST_HEAD(nchash_list, namecache); 132 133 struct nchash_head { 134 struct nchash_list list; 135 struct spinlock spin; 136 }; 137 138 static struct nchash_head *nchashtbl; 139 static struct namecache_list ncneglist; 140 static struct spinlock ncspin; 141 142 /* 143 * ncvp_debug - debug cache_fromvp(). This is used by the NFS server 144 * to create the namecache infrastructure leading to a dangling vnode. 145 * 146 * 0 Only errors are reported 147 * 1 Successes are reported 148 * 2 Successes + the whole directory scan is reported 149 * 3 Force the directory scan code run as if the parent vnode did not 150 * have a namecache record, even if it does have one. 151 */ 152 static int ncvp_debug; 153 SYSCTL_INT(_debug, OID_AUTO, ncvp_debug, CTLFLAG_RW, &ncvp_debug, 0, ""); 154 155 static u_long nchash; /* size of hash table */ 156 SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, ""); 157 158 static int ncnegfactor = 16; /* ratio of negative entries */ 159 SYSCTL_INT(_debug, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, ""); 160 161 static int nclockwarn; /* warn on locked entries in ticks */ 162 SYSCTL_INT(_debug, OID_AUTO, nclockwarn, CTLFLAG_RW, &nclockwarn, 0, ""); 163 164 static int numneg; /* number of cache entries allocated */ 165 SYSCTL_INT(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, ""); 166 167 static int numdefered; /* number of cache entries allocated */ 168 SYSCTL_INT(_debug, OID_AUTO, numdefered, CTLFLAG_RD, &numdefered, 0, ""); 169 170 static int numcache; /* number of cache entries allocated */ 171 SYSCTL_INT(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, ""); 172 173 SYSCTL_INT(_debug, OID_AUTO, vnsize, CTLFLAG_RD, 0, sizeof(struct vnode), ""); 174 SYSCTL_INT(_debug, OID_AUTO, ncsize, CTLFLAG_RD, 0, sizeof(struct namecache), ""); 175 176 int cache_mpsafe = 1; 177 SYSCTL_INT(_vfs, OID_AUTO, cache_mpsafe, CTLFLAG_RW, &cache_mpsafe, 0, ""); 178 179 static int cache_resolve_mp(struct mount *mp); 180 static struct vnode *cache_dvpref(struct namecache *ncp); 181 static void _cache_lock(struct namecache *ncp); 182 static void _cache_setunresolved(struct namecache *ncp); 183 static void _cache_cleanneg(int count); 184 static void _cache_cleandefered(void); 185 186 /* 187 * The new name cache statistics 188 */ 189 SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, "Name cache statistics"); 190 #define STATNODE(mode, name, var) \ 191 SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, mode, var, 0, ""); 192 STATNODE(CTLFLAG_RD, numneg, &numneg); 193 STATNODE(CTLFLAG_RD, numcache, &numcache); 194 static u_long numcalls; STATNODE(CTLFLAG_RD, numcalls, &numcalls); 195 static u_long dothits; STATNODE(CTLFLAG_RD, dothits, &dothits); 196 static u_long dotdothits; STATNODE(CTLFLAG_RD, dotdothits, &dotdothits); 197 static u_long numchecks; STATNODE(CTLFLAG_RD, numchecks, &numchecks); 198 static u_long nummiss; STATNODE(CTLFLAG_RD, nummiss, &nummiss); 199 static u_long nummisszap; STATNODE(CTLFLAG_RD, nummisszap, &nummisszap); 200 static u_long numposzaps; STATNODE(CTLFLAG_RD, numposzaps, &numposzaps); 201 static u_long numposhits; STATNODE(CTLFLAG_RD, numposhits, &numposhits); 202 static u_long numnegzaps; STATNODE(CTLFLAG_RD, numnegzaps, &numnegzaps); 203 static u_long numneghits; STATNODE(CTLFLAG_RD, numneghits, &numneghits); 204 205 struct nchstats nchstats[SMP_MAXCPU]; 206 /* 207 * Export VFS cache effectiveness statistics to user-land. 208 * 209 * The statistics are left for aggregation to user-land so 210 * neat things can be achieved, like observing per-CPU cache 211 * distribution. 212 */ 213 static int 214 sysctl_nchstats(SYSCTL_HANDLER_ARGS) 215 { 216 struct globaldata *gd; 217 int i, error; 218 219 error = 0; 220 for (i = 0; i < ncpus; ++i) { 221 gd = globaldata_find(i); 222 if ((error = SYSCTL_OUT(req, (void *)&(*gd->gd_nchstats), 223 sizeof(struct nchstats)))) 224 break; 225 } 226 227 return (error); 228 } 229 SYSCTL_PROC(_vfs_cache, OID_AUTO, nchstats, CTLTYPE_OPAQUE|CTLFLAG_RD, 230 0, 0, sysctl_nchstats, "S,nchstats", "VFS cache effectiveness statistics"); 231 232 static struct namecache *cache_zap(struct namecache *ncp, int nonblock); 233 234 /* 235 * Namespace locking. The caller must already hold a reference to the 236 * namecache structure in order to lock/unlock it. This function prevents 237 * the namespace from being created or destroyed by accessors other then 238 * the lock holder. 239 * 240 * Note that holding a locked namecache structure prevents other threads 241 * from making namespace changes (e.g. deleting or creating), prevents 242 * vnode association state changes by other threads, and prevents the 243 * namecache entry from being resolved or unresolved by other threads. 244 * 245 * The lock owner has full authority to associate/disassociate vnodes 246 * and resolve/unresolve the locked ncp. 247 * 248 * The primary lock field is nc_exlocks. nc_locktd is set after the 249 * fact (when locking) or cleared prior to unlocking. 250 * 251 * WARNING! Holding a locked ncp will prevent a vnode from being destroyed 252 * or recycled, but it does NOT help you if the vnode had already 253 * initiated a recyclement. If this is important, use cache_get() 254 * rather then cache_lock() (and deal with the differences in the 255 * way the refs counter is handled). Or, alternatively, make an 256 * unconditional call to cache_validate() or cache_resolve() 257 * after cache_lock() returns. 258 * 259 * MPSAFE 260 */ 261 static 262 void 263 _cache_lock(struct namecache *ncp) 264 { 265 thread_t td; 266 int didwarn; 267 int error; 268 u_int count; 269 270 KKASSERT(ncp->nc_refs != 0); 271 didwarn = 0; 272 td = curthread; 273 274 for (;;) { 275 count = ncp->nc_exlocks; 276 277 if (count == 0) { 278 if (atomic_cmpset_int(&ncp->nc_exlocks, 0, 1)) { 279 /* 280 * The vp associated with a locked ncp must 281 * be held to prevent it from being recycled. 282 * 283 * WARNING! If VRECLAIMED is set the vnode 284 * could already be in the middle of a recycle. 285 * Callers must use cache_vref() or 286 * cache_vget() on the locked ncp to 287 * validate the vp or set the cache entry 288 * to unresolved. 289 * 290 * NOTE! vhold() is allowed if we hold a 291 * lock on the ncp (which we do). 292 */ 293 ncp->nc_locktd = td; 294 if (ncp->nc_vp) 295 vhold(ncp->nc_vp); /* MPSAFE */ 296 break; 297 } 298 /* cmpset failed */ 299 continue; 300 } 301 if (ncp->nc_locktd == td) { 302 if (atomic_cmpset_int(&ncp->nc_exlocks, count, 303 count + 1)) { 304 break; 305 } 306 /* cmpset failed */ 307 continue; 308 } 309 tsleep_interlock(ncp, 0); 310 if (atomic_cmpset_int(&ncp->nc_exlocks, count, 311 count | NC_EXLOCK_REQ) == 0) { 312 /* cmpset failed */ 313 continue; 314 } 315 error = tsleep(ncp, PINTERLOCKED, "clock", nclockwarn); 316 if (error == EWOULDBLOCK) { 317 if (didwarn == 0) { 318 didwarn = ticks; 319 kprintf("[diagnostic] cache_lock: blocked " 320 "on %p", 321 ncp); 322 kprintf(" \"%*.*s\"\n", 323 ncp->nc_nlen, ncp->nc_nlen, 324 ncp->nc_name); 325 } 326 } 327 } 328 if (didwarn) { 329 kprintf("[diagnostic] cache_lock: unblocked %*.*s after " 330 "%d secs\n", 331 ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name, 332 (int)(ticks - didwarn) / hz); 333 } 334 } 335 336 /* 337 * NOTE: nc_refs may be zero if the ncp is interlocked by circumstance, 338 * such as the case where one of its children is locked. 339 * 340 * MPSAFE 341 */ 342 static 343 int 344 _cache_lock_nonblock(struct namecache *ncp) 345 { 346 thread_t td; 347 u_int count; 348 349 td = curthread; 350 351 for (;;) { 352 count = ncp->nc_exlocks; 353 354 if (count == 0) { 355 if (atomic_cmpset_int(&ncp->nc_exlocks, 0, 1)) { 356 /* 357 * The vp associated with a locked ncp must 358 * be held to prevent it from being recycled. 359 * 360 * WARNING! If VRECLAIMED is set the vnode 361 * could already be in the middle of a recycle. 362 * Callers must use cache_vref() or 363 * cache_vget() on the locked ncp to 364 * validate the vp or set the cache entry 365 * to unresolved. 366 * 367 * NOTE! vhold() is allowed if we hold a 368 * lock on the ncp (which we do). 369 */ 370 ncp->nc_locktd = td; 371 if (ncp->nc_vp) 372 vhold(ncp->nc_vp); /* MPSAFE */ 373 break; 374 } 375 /* cmpset failed */ 376 continue; 377 } 378 if (ncp->nc_locktd == td) { 379 if (atomic_cmpset_int(&ncp->nc_exlocks, count, 380 count + 1)) { 381 break; 382 } 383 /* cmpset failed */ 384 continue; 385 } 386 return(EWOULDBLOCK); 387 } 388 return(0); 389 } 390 391 /* 392 * Helper function 393 * 394 * NOTE: nc_refs can be 0 (degenerate case during _cache_drop). 395 * 396 * nc_locktd must be NULLed out prior to nc_exlocks getting cleared. 397 * 398 * MPSAFE 399 */ 400 static 401 void 402 _cache_unlock(struct namecache *ncp) 403 { 404 thread_t td __debugvar = curthread; 405 u_int count; 406 407 KKASSERT(ncp->nc_refs >= 0); 408 KKASSERT(ncp->nc_exlocks > 0); 409 KKASSERT(ncp->nc_locktd == td); 410 411 count = ncp->nc_exlocks; 412 if ((count & ~NC_EXLOCK_REQ) == 1) { 413 ncp->nc_locktd = NULL; 414 if (ncp->nc_vp) 415 vdrop(ncp->nc_vp); 416 } 417 for (;;) { 418 if ((count & ~NC_EXLOCK_REQ) == 1) { 419 if (atomic_cmpset_int(&ncp->nc_exlocks, count, 0)) { 420 if (count & NC_EXLOCK_REQ) 421 wakeup(ncp); 422 break; 423 } 424 } else { 425 if (atomic_cmpset_int(&ncp->nc_exlocks, count, 426 count - 1)) { 427 break; 428 } 429 } 430 count = ncp->nc_exlocks; 431 } 432 } 433 434 435 /* 436 * cache_hold() and cache_drop() prevent the premature deletion of a 437 * namecache entry but do not prevent operations (such as zapping) on 438 * that namecache entry. 439 * 440 * This routine may only be called from outside this source module if 441 * nc_refs is already at least 1. 442 * 443 * This is a rare case where callers are allowed to hold a spinlock, 444 * so we can't ourselves. 445 * 446 * MPSAFE 447 */ 448 static __inline 449 struct namecache * 450 _cache_hold(struct namecache *ncp) 451 { 452 atomic_add_int(&ncp->nc_refs, 1); 453 return(ncp); 454 } 455 456 /* 457 * Drop a cache entry, taking care to deal with races. 458 * 459 * For potential 1->0 transitions we must hold the ncp lock to safely 460 * test its flags. An unresolved entry with no children must be zapped 461 * to avoid leaks. 462 * 463 * The call to cache_zap() itself will handle all remaining races and 464 * will decrement the ncp's refs regardless. If we are resolved or 465 * have children nc_refs can safely be dropped to 0 without having to 466 * zap the entry. 467 * 468 * NOTE: cache_zap() will re-check nc_refs and nc_list in a MPSAFE fashion. 469 * 470 * NOTE: cache_zap() may return a non-NULL referenced parent which must 471 * be dropped in a loop. 472 * 473 * MPSAFE 474 */ 475 static __inline 476 void 477 _cache_drop(struct namecache *ncp) 478 { 479 int refs; 480 481 while (ncp) { 482 KKASSERT(ncp->nc_refs > 0); 483 refs = ncp->nc_refs; 484 485 if (refs == 1) { 486 if (_cache_lock_nonblock(ncp) == 0) { 487 ncp->nc_flag &= ~NCF_DEFEREDZAP; 488 if ((ncp->nc_flag & NCF_UNRESOLVED) && 489 TAILQ_EMPTY(&ncp->nc_list)) { 490 ncp = cache_zap(ncp, 1); 491 continue; 492 } 493 if (atomic_cmpset_int(&ncp->nc_refs, 1, 0)) { 494 _cache_unlock(ncp); 495 break; 496 } 497 _cache_unlock(ncp); 498 } 499 } else { 500 if (atomic_cmpset_int(&ncp->nc_refs, refs, refs - 1)) 501 break; 502 } 503 cpu_pause(); 504 } 505 } 506 507 /* 508 * Link a new namecache entry to its parent and to the hash table. Be 509 * careful to avoid races if vhold() blocks in the future. 510 * 511 * Both ncp and par must be referenced and locked. 512 * 513 * NOTE: The hash table spinlock is likely held during this call, we 514 * can't do anything fancy. 515 * 516 * MPSAFE 517 */ 518 static void 519 _cache_link_parent(struct namecache *ncp, struct namecache *par, 520 struct nchash_head *nchpp) 521 { 522 KKASSERT(ncp->nc_parent == NULL); 523 ncp->nc_parent = par; 524 ncp->nc_head = nchpp; 525 526 /* 527 * Set inheritance flags. Note that the parent flags may be 528 * stale due to getattr potentially not having been run yet 529 * (it gets run during nlookup()'s). 530 */ 531 ncp->nc_flag &= ~(NCF_SF_PNOCACHE | NCF_UF_PCACHE); 532 if (par->nc_flag & (NCF_SF_NOCACHE | NCF_SF_PNOCACHE)) 533 ncp->nc_flag |= NCF_SF_PNOCACHE; 534 if (par->nc_flag & (NCF_UF_CACHE | NCF_UF_PCACHE)) 535 ncp->nc_flag |= NCF_UF_PCACHE; 536 537 LIST_INSERT_HEAD(&nchpp->list, ncp, nc_hash); 538 539 if (TAILQ_EMPTY(&par->nc_list)) { 540 TAILQ_INSERT_HEAD(&par->nc_list, ncp, nc_entry); 541 /* 542 * Any vp associated with an ncp which has children must 543 * be held to prevent it from being recycled. 544 */ 545 if (par->nc_vp) 546 vhold(par->nc_vp); 547 } else { 548 TAILQ_INSERT_HEAD(&par->nc_list, ncp, nc_entry); 549 } 550 } 551 552 /* 553 * Remove the parent and hash associations from a namecache structure. 554 * If this is the last child of the parent the cache_drop(par) will 555 * attempt to recursively zap the parent. 556 * 557 * ncp must be locked. This routine will acquire a temporary lock on 558 * the parent as wlel as the appropriate hash chain. 559 * 560 * MPSAFE 561 */ 562 static void 563 _cache_unlink_parent(struct namecache *ncp) 564 { 565 struct namecache *par; 566 struct vnode *dropvp; 567 568 if ((par = ncp->nc_parent) != NULL) { 569 KKASSERT(ncp->nc_parent == par); 570 _cache_hold(par); 571 _cache_lock(par); 572 spin_lock_wr(&ncp->nc_head->spin); 573 LIST_REMOVE(ncp, nc_hash); 574 TAILQ_REMOVE(&par->nc_list, ncp, nc_entry); 575 dropvp = NULL; 576 if (par->nc_vp && TAILQ_EMPTY(&par->nc_list)) 577 dropvp = par->nc_vp; 578 spin_unlock_wr(&ncp->nc_head->spin); 579 ncp->nc_parent = NULL; 580 ncp->nc_head = NULL; 581 _cache_unlock(par); 582 _cache_drop(par); 583 584 /* 585 * We can only safely vdrop with no spinlocks held. 586 */ 587 if (dropvp) 588 vdrop(dropvp); 589 } 590 } 591 592 /* 593 * Allocate a new namecache structure. Most of the code does not require 594 * zero-termination of the string but it makes vop_compat_ncreate() easier. 595 * 596 * MPSAFE 597 */ 598 static struct namecache * 599 cache_alloc(int nlen) 600 { 601 struct namecache *ncp; 602 603 ncp = kmalloc(sizeof(*ncp), M_VFSCACHE, M_WAITOK|M_ZERO); 604 if (nlen) 605 ncp->nc_name = kmalloc(nlen + 1, M_VFSCACHE, M_WAITOK); 606 ncp->nc_nlen = nlen; 607 ncp->nc_flag = NCF_UNRESOLVED; 608 ncp->nc_error = ENOTCONN; /* needs to be resolved */ 609 ncp->nc_refs = 1; 610 611 TAILQ_INIT(&ncp->nc_list); 612 _cache_lock(ncp); 613 return(ncp); 614 } 615 616 /* 617 * Can only be called for the case where the ncp has never been 618 * associated with anything (so no spinlocks are needed). 619 * 620 * MPSAFE 621 */ 622 static void 623 _cache_free(struct namecache *ncp) 624 { 625 KKASSERT(ncp->nc_refs == 1 && ncp->nc_exlocks == 1); 626 if (ncp->nc_name) 627 kfree(ncp->nc_name, M_VFSCACHE); 628 kfree(ncp, M_VFSCACHE); 629 } 630 631 /* 632 * MPSAFE 633 */ 634 void 635 cache_zero(struct nchandle *nch) 636 { 637 nch->ncp = NULL; 638 nch->mount = NULL; 639 } 640 641 /* 642 * Ref and deref a namecache structure. 643 * 644 * The caller must specify a stable ncp pointer, typically meaning the 645 * ncp is already referenced but this can also occur indirectly through 646 * e.g. holding a lock on a direct child. 647 * 648 * WARNING: Caller may hold an unrelated read spinlock, which means we can't 649 * use read spinlocks here. 650 * 651 * MPSAFE if nch is 652 */ 653 struct nchandle * 654 cache_hold(struct nchandle *nch) 655 { 656 _cache_hold(nch->ncp); 657 atomic_add_int(&nch->mount->mnt_refs, 1); 658 return(nch); 659 } 660 661 /* 662 * Create a copy of a namecache handle for an already-referenced 663 * entry. 664 * 665 * MPSAFE if nch is 666 */ 667 void 668 cache_copy(struct nchandle *nch, struct nchandle *target) 669 { 670 *target = *nch; 671 if (target->ncp) 672 _cache_hold(target->ncp); 673 atomic_add_int(&nch->mount->mnt_refs, 1); 674 } 675 676 /* 677 * MPSAFE if nch is 678 */ 679 void 680 cache_changemount(struct nchandle *nch, struct mount *mp) 681 { 682 atomic_add_int(&nch->mount->mnt_refs, -1); 683 nch->mount = mp; 684 atomic_add_int(&nch->mount->mnt_refs, 1); 685 } 686 687 /* 688 * MPSAFE 689 */ 690 void 691 cache_drop(struct nchandle *nch) 692 { 693 atomic_add_int(&nch->mount->mnt_refs, -1); 694 _cache_drop(nch->ncp); 695 nch->ncp = NULL; 696 nch->mount = NULL; 697 } 698 699 /* 700 * MPSAFE 701 */ 702 void 703 cache_lock(struct nchandle *nch) 704 { 705 _cache_lock(nch->ncp); 706 } 707 708 /* 709 * Relock nch1 given an unlocked nch1 and a locked nch2. The caller 710 * is responsible for checking both for validity on return as they 711 * may have become invalid. 712 * 713 * We have to deal with potential deadlocks here, just ping pong 714 * the lock until we get it (we will always block somewhere when 715 * looping so this is not cpu-intensive). 716 * 717 * which = 0 nch1 not locked, nch2 is locked 718 * which = 1 nch1 is locked, nch2 is not locked 719 */ 720 void 721 cache_relock(struct nchandle *nch1, struct ucred *cred1, 722 struct nchandle *nch2, struct ucred *cred2) 723 { 724 int which; 725 726 which = 0; 727 728 for (;;) { 729 if (which == 0) { 730 if (cache_lock_nonblock(nch1) == 0) { 731 cache_resolve(nch1, cred1); 732 break; 733 } 734 cache_unlock(nch2); 735 cache_lock(nch1); 736 cache_resolve(nch1, cred1); 737 which = 1; 738 } else { 739 if (cache_lock_nonblock(nch2) == 0) { 740 cache_resolve(nch2, cred2); 741 break; 742 } 743 cache_unlock(nch1); 744 cache_lock(nch2); 745 cache_resolve(nch2, cred2); 746 which = 0; 747 } 748 } 749 } 750 751 /* 752 * MPSAFE 753 */ 754 int 755 cache_lock_nonblock(struct nchandle *nch) 756 { 757 return(_cache_lock_nonblock(nch->ncp)); 758 } 759 760 761 /* 762 * MPSAFE 763 */ 764 void 765 cache_unlock(struct nchandle *nch) 766 { 767 _cache_unlock(nch->ncp); 768 } 769 770 /* 771 * ref-and-lock, unlock-and-deref functions. 772 * 773 * This function is primarily used by nlookup. Even though cache_lock 774 * holds the vnode, it is possible that the vnode may have already 775 * initiated a recyclement. 776 * 777 * We want cache_get() to return a definitively usable vnode or a 778 * definitively unresolved ncp. 779 * 780 * MPSAFE 781 */ 782 static 783 struct namecache * 784 _cache_get(struct namecache *ncp) 785 { 786 _cache_hold(ncp); 787 _cache_lock(ncp); 788 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) 789 _cache_setunresolved(ncp); 790 return(ncp); 791 } 792 793 /* 794 * This is a special form of _cache_lock() which only succeeds if 795 * it can get a pristine, non-recursive lock. The caller must have 796 * already ref'd the ncp. 797 * 798 * On success the ncp will be locked, on failure it will not. The 799 * ref count does not change either way. 800 * 801 * We want _cache_lock_special() (on success) to return a definitively 802 * usable vnode or a definitively unresolved ncp. 803 * 804 * MPSAFE 805 */ 806 static int 807 _cache_lock_special(struct namecache *ncp) 808 { 809 if (_cache_lock_nonblock(ncp) == 0) { 810 if ((ncp->nc_exlocks & ~NC_EXLOCK_REQ) == 1) { 811 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) 812 _cache_setunresolved(ncp); 813 return(0); 814 } 815 _cache_unlock(ncp); 816 } 817 return(EWOULDBLOCK); 818 } 819 820 821 /* 822 * NOTE: The same nchandle can be passed for both arguments. 823 * 824 * MPSAFE 825 */ 826 void 827 cache_get(struct nchandle *nch, struct nchandle *target) 828 { 829 KKASSERT(nch->ncp->nc_refs > 0); 830 target->mount = nch->mount; 831 target->ncp = _cache_get(nch->ncp); 832 atomic_add_int(&target->mount->mnt_refs, 1); 833 } 834 835 /* 836 * MPSAFE 837 */ 838 static __inline 839 void 840 _cache_put(struct namecache *ncp) 841 { 842 _cache_unlock(ncp); 843 _cache_drop(ncp); 844 } 845 846 /* 847 * MPSAFE 848 */ 849 void 850 cache_put(struct nchandle *nch) 851 { 852 atomic_add_int(&nch->mount->mnt_refs, -1); 853 _cache_put(nch->ncp); 854 nch->ncp = NULL; 855 nch->mount = NULL; 856 } 857 858 /* 859 * Resolve an unresolved ncp by associating a vnode with it. If the 860 * vnode is NULL, a negative cache entry is created. 861 * 862 * The ncp should be locked on entry and will remain locked on return. 863 * 864 * MPSAFE 865 */ 866 static 867 void 868 _cache_setvp(struct mount *mp, struct namecache *ncp, struct vnode *vp) 869 { 870 KKASSERT(ncp->nc_flag & NCF_UNRESOLVED); 871 872 if (vp != NULL) { 873 /* 874 * Any vp associated with an ncp which has children must 875 * be held. Any vp associated with a locked ncp must be held. 876 */ 877 if (!TAILQ_EMPTY(&ncp->nc_list)) 878 vhold(vp); 879 spin_lock_wr(&vp->v_spinlock); 880 ncp->nc_vp = vp; 881 TAILQ_INSERT_HEAD(&vp->v_namecache, ncp, nc_vnode); 882 spin_unlock_wr(&vp->v_spinlock); 883 if (ncp->nc_exlocks) 884 vhold(vp); 885 886 /* 887 * Set auxiliary flags 888 */ 889 switch(vp->v_type) { 890 case VDIR: 891 ncp->nc_flag |= NCF_ISDIR; 892 break; 893 case VLNK: 894 ncp->nc_flag |= NCF_ISSYMLINK; 895 /* XXX cache the contents of the symlink */ 896 break; 897 default: 898 break; 899 } 900 atomic_add_int(&numcache, 1); 901 ncp->nc_error = 0; 902 } else { 903 /* 904 * When creating a negative cache hit we set the 905 * namecache_gen. A later resolve will clean out the 906 * negative cache hit if the mount point's namecache_gen 907 * has changed. Used by devfs, could also be used by 908 * other remote FSs. 909 */ 910 ncp->nc_vp = NULL; 911 spin_lock_wr(&ncspin); 912 TAILQ_INSERT_TAIL(&ncneglist, ncp, nc_vnode); 913 ++numneg; 914 spin_unlock_wr(&ncspin); 915 ncp->nc_error = ENOENT; 916 if (mp) 917 ncp->nc_namecache_gen = mp->mnt_namecache_gen; 918 } 919 ncp->nc_flag &= ~(NCF_UNRESOLVED | NCF_DEFEREDZAP); 920 } 921 922 /* 923 * MPSAFE 924 */ 925 void 926 cache_setvp(struct nchandle *nch, struct vnode *vp) 927 { 928 _cache_setvp(nch->mount, nch->ncp, vp); 929 } 930 931 /* 932 * MPSAFE 933 */ 934 void 935 cache_settimeout(struct nchandle *nch, int nticks) 936 { 937 struct namecache *ncp = nch->ncp; 938 939 if ((ncp->nc_timeout = ticks + nticks) == 0) 940 ncp->nc_timeout = 1; 941 } 942 943 /* 944 * Disassociate the vnode or negative-cache association and mark a 945 * namecache entry as unresolved again. Note that the ncp is still 946 * left in the hash table and still linked to its parent. 947 * 948 * The ncp should be locked and refd on entry and will remain locked and refd 949 * on return. 950 * 951 * This routine is normally never called on a directory containing children. 952 * However, NFS often does just that in its rename() code as a cop-out to 953 * avoid complex namespace operations. This disconnects a directory vnode 954 * from its namecache and can cause the OLDAPI and NEWAPI to get out of 955 * sync. 956 * 957 * MPSAFE 958 */ 959 static 960 void 961 _cache_setunresolved(struct namecache *ncp) 962 { 963 struct vnode *vp; 964 965 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) { 966 ncp->nc_flag |= NCF_UNRESOLVED; 967 ncp->nc_timeout = 0; 968 ncp->nc_error = ENOTCONN; 969 if ((vp = ncp->nc_vp) != NULL) { 970 atomic_add_int(&numcache, -1); 971 spin_lock_wr(&vp->v_spinlock); 972 ncp->nc_vp = NULL; 973 TAILQ_REMOVE(&vp->v_namecache, ncp, nc_vnode); 974 spin_unlock_wr(&vp->v_spinlock); 975 976 /* 977 * Any vp associated with an ncp with children is 978 * held by that ncp. Any vp associated with a locked 979 * ncp is held by that ncp. These conditions must be 980 * undone when the vp is cleared out from the ncp. 981 */ 982 if (!TAILQ_EMPTY(&ncp->nc_list)) 983 vdrop(vp); 984 if (ncp->nc_exlocks) 985 vdrop(vp); 986 } else { 987 spin_lock_wr(&ncspin); 988 TAILQ_REMOVE(&ncneglist, ncp, nc_vnode); 989 --numneg; 990 spin_unlock_wr(&ncspin); 991 } 992 ncp->nc_flag &= ~(NCF_WHITEOUT|NCF_ISDIR|NCF_ISSYMLINK); 993 } 994 } 995 996 /* 997 * The cache_nresolve() code calls this function to automatically 998 * set a resolved cache element to unresolved if it has timed out 999 * or if it is a negative cache hit and the mount point namecache_gen 1000 * has changed. 1001 * 1002 * MPSAFE 1003 */ 1004 static __inline void 1005 _cache_auto_unresolve(struct mount *mp, struct namecache *ncp) 1006 { 1007 /* 1008 * Already in an unresolved state, nothing to do. 1009 */ 1010 if (ncp->nc_flag & NCF_UNRESOLVED) 1011 return; 1012 1013 /* 1014 * Try to zap entries that have timed out. We have 1015 * to be careful here because locked leafs may depend 1016 * on the vnode remaining intact in a parent, so only 1017 * do this under very specific conditions. 1018 */ 1019 if (ncp->nc_timeout && (int)(ncp->nc_timeout - ticks) < 0 && 1020 TAILQ_EMPTY(&ncp->nc_list)) { 1021 _cache_setunresolved(ncp); 1022 return; 1023 } 1024 1025 /* 1026 * If a resolved negative cache hit is invalid due to 1027 * the mount's namecache generation being bumped, zap it. 1028 */ 1029 if (ncp->nc_vp == NULL && 1030 ncp->nc_namecache_gen != mp->mnt_namecache_gen) { 1031 _cache_setunresolved(ncp); 1032 return; 1033 } 1034 } 1035 1036 /* 1037 * MPSAFE 1038 */ 1039 void 1040 cache_setunresolved(struct nchandle *nch) 1041 { 1042 _cache_setunresolved(nch->ncp); 1043 } 1044 1045 /* 1046 * Determine if we can clear NCF_ISMOUNTPT by scanning the mountlist 1047 * looking for matches. This flag tells the lookup code when it must 1048 * check for a mount linkage and also prevents the directories in question 1049 * from being deleted or renamed. 1050 * 1051 * MPSAFE 1052 */ 1053 static 1054 int 1055 cache_clrmountpt_callback(struct mount *mp, void *data) 1056 { 1057 struct nchandle *nch = data; 1058 1059 if (mp->mnt_ncmounton.ncp == nch->ncp) 1060 return(1); 1061 if (mp->mnt_ncmountpt.ncp == nch->ncp) 1062 return(1); 1063 return(0); 1064 } 1065 1066 /* 1067 * MPSAFE 1068 */ 1069 void 1070 cache_clrmountpt(struct nchandle *nch) 1071 { 1072 int count; 1073 1074 count = mountlist_scan(cache_clrmountpt_callback, nch, 1075 MNTSCAN_FORWARD|MNTSCAN_NOBUSY); 1076 if (count == 0) 1077 nch->ncp->nc_flag &= ~NCF_ISMOUNTPT; 1078 } 1079 1080 /* 1081 * Invalidate portions of the namecache topology given a starting entry. 1082 * The passed ncp is set to an unresolved state and: 1083 * 1084 * The passed ncp must be referencxed and locked. The routine may unlock 1085 * and relock ncp several times, and will recheck the children and loop 1086 * to catch races. When done the passed ncp will be returned with the 1087 * reference and lock intact. 1088 * 1089 * CINV_DESTROY - Set a flag in the passed ncp entry indicating 1090 * that the physical underlying nodes have been 1091 * destroyed... as in deleted. For example, when 1092 * a directory is removed. This will cause record 1093 * lookups on the name to no longer be able to find 1094 * the record and tells the resolver to return failure 1095 * rather then trying to resolve through the parent. 1096 * 1097 * The topology itself, including ncp->nc_name, 1098 * remains intact. 1099 * 1100 * This only applies to the passed ncp, if CINV_CHILDREN 1101 * is specified the children are not flagged. 1102 * 1103 * CINV_CHILDREN - Set all children (recursively) to an unresolved 1104 * state as well. 1105 * 1106 * Note that this will also have the side effect of 1107 * cleaning out any unreferenced nodes in the topology 1108 * from the leaves up as the recursion backs out. 1109 * 1110 * Note that the topology for any referenced nodes remains intact, but 1111 * the nodes will be marked as having been destroyed and will be set 1112 * to an unresolved state. 1113 * 1114 * It is possible for cache_inval() to race a cache_resolve(), meaning that 1115 * the namecache entry may not actually be invalidated on return if it was 1116 * revalidated while recursing down into its children. This code guarentees 1117 * that the node(s) will go through an invalidation cycle, but does not 1118 * guarentee that they will remain in an invalidated state. 1119 * 1120 * Returns non-zero if a revalidation was detected during the invalidation 1121 * recursion, zero otherwise. Note that since only the original ncp is 1122 * locked the revalidation ultimately can only indicate that the original ncp 1123 * *MIGHT* no have been reresolved. 1124 * 1125 * DEEP RECURSION HANDLING - If a recursive invalidation recurses deeply we 1126 * have to avoid blowing out the kernel stack. We do this by saving the 1127 * deep namecache node and aborting the recursion, then re-recursing at that 1128 * node using a depth-first algorithm in order to allow multiple deep 1129 * recursions to chain through each other, then we restart the invalidation 1130 * from scratch. 1131 * 1132 * MPSAFE 1133 */ 1134 1135 struct cinvtrack { 1136 struct namecache *resume_ncp; 1137 int depth; 1138 }; 1139 1140 static int _cache_inval_internal(struct namecache *, int, struct cinvtrack *); 1141 1142 static 1143 int 1144 _cache_inval(struct namecache *ncp, int flags) 1145 { 1146 struct cinvtrack track; 1147 struct namecache *ncp2; 1148 int r; 1149 1150 track.depth = 0; 1151 track.resume_ncp = NULL; 1152 1153 for (;;) { 1154 r = _cache_inval_internal(ncp, flags, &track); 1155 if (track.resume_ncp == NULL) 1156 break; 1157 kprintf("Warning: deep namecache recursion at %s\n", 1158 ncp->nc_name); 1159 _cache_unlock(ncp); 1160 while ((ncp2 = track.resume_ncp) != NULL) { 1161 track.resume_ncp = NULL; 1162 _cache_lock(ncp2); 1163 _cache_inval_internal(ncp2, flags & ~CINV_DESTROY, 1164 &track); 1165 _cache_put(ncp2); 1166 } 1167 _cache_lock(ncp); 1168 } 1169 return(r); 1170 } 1171 1172 int 1173 cache_inval(struct nchandle *nch, int flags) 1174 { 1175 return(_cache_inval(nch->ncp, flags)); 1176 } 1177 1178 /* 1179 * Helper for _cache_inval(). The passed ncp is refd and locked and 1180 * remains that way on return, but may be unlocked/relocked multiple 1181 * times by the routine. 1182 */ 1183 static int 1184 _cache_inval_internal(struct namecache *ncp, int flags, struct cinvtrack *track) 1185 { 1186 struct namecache *kid; 1187 struct namecache *nextkid; 1188 int rcnt = 0; 1189 1190 KKASSERT(ncp->nc_exlocks); 1191 1192 _cache_setunresolved(ncp); 1193 if (flags & CINV_DESTROY) 1194 ncp->nc_flag |= NCF_DESTROYED; 1195 if ((flags & CINV_CHILDREN) && 1196 (kid = TAILQ_FIRST(&ncp->nc_list)) != NULL 1197 ) { 1198 _cache_hold(kid); 1199 if (++track->depth > MAX_RECURSION_DEPTH) { 1200 track->resume_ncp = ncp; 1201 _cache_hold(ncp); 1202 ++rcnt; 1203 } 1204 _cache_unlock(ncp); 1205 while (kid) { 1206 if (track->resume_ncp) { 1207 _cache_drop(kid); 1208 break; 1209 } 1210 if ((nextkid = TAILQ_NEXT(kid, nc_entry)) != NULL) 1211 _cache_hold(nextkid); 1212 if ((kid->nc_flag & NCF_UNRESOLVED) == 0 || 1213 TAILQ_FIRST(&kid->nc_list) 1214 ) { 1215 _cache_lock(kid); 1216 rcnt += _cache_inval_internal(kid, flags & ~CINV_DESTROY, track); 1217 _cache_unlock(kid); 1218 } 1219 _cache_drop(kid); 1220 kid = nextkid; 1221 } 1222 --track->depth; 1223 _cache_lock(ncp); 1224 } 1225 1226 /* 1227 * Someone could have gotten in there while ncp was unlocked, 1228 * retry if so. 1229 */ 1230 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) 1231 ++rcnt; 1232 return (rcnt); 1233 } 1234 1235 /* 1236 * Invalidate a vnode's namecache associations. To avoid races against 1237 * the resolver we do not invalidate a node which we previously invalidated 1238 * but which was then re-resolved while we were in the invalidation loop. 1239 * 1240 * Returns non-zero if any namecache entries remain after the invalidation 1241 * loop completed. 1242 * 1243 * NOTE: Unlike the namecache topology which guarentees that ncp's will not 1244 * be ripped out of the topology while held, the vnode's v_namecache 1245 * list has no such restriction. NCP's can be ripped out of the list 1246 * at virtually any time if not locked, even if held. 1247 * 1248 * In addition, the v_namecache list itself must be locked via 1249 * the vnode's spinlock. 1250 * 1251 * MPSAFE 1252 */ 1253 int 1254 cache_inval_vp(struct vnode *vp, int flags) 1255 { 1256 struct namecache *ncp; 1257 struct namecache *next; 1258 1259 restart: 1260 spin_lock_wr(&vp->v_spinlock); 1261 ncp = TAILQ_FIRST(&vp->v_namecache); 1262 if (ncp) 1263 _cache_hold(ncp); 1264 while (ncp) { 1265 /* loop entered with ncp held and vp spin-locked */ 1266 if ((next = TAILQ_NEXT(ncp, nc_vnode)) != NULL) 1267 _cache_hold(next); 1268 spin_unlock_wr(&vp->v_spinlock); 1269 _cache_lock(ncp); 1270 if (ncp->nc_vp != vp) { 1271 kprintf("Warning: cache_inval_vp: race-A detected on " 1272 "%s\n", ncp->nc_name); 1273 _cache_put(ncp); 1274 if (next) 1275 _cache_drop(next); 1276 goto restart; 1277 } 1278 _cache_inval(ncp, flags); 1279 _cache_put(ncp); /* also releases reference */ 1280 ncp = next; 1281 spin_lock_wr(&vp->v_spinlock); 1282 if (ncp && ncp->nc_vp != vp) { 1283 spin_unlock_wr(&vp->v_spinlock); 1284 kprintf("Warning: cache_inval_vp: race-B detected on " 1285 "%s\n", ncp->nc_name); 1286 _cache_drop(ncp); 1287 goto restart; 1288 } 1289 } 1290 spin_unlock_wr(&vp->v_spinlock); 1291 return(TAILQ_FIRST(&vp->v_namecache) != NULL); 1292 } 1293 1294 /* 1295 * This routine is used instead of the normal cache_inval_vp() when we 1296 * are trying to recycle otherwise good vnodes. 1297 * 1298 * Return 0 on success, non-zero if not all namecache records could be 1299 * disassociated from the vnode (for various reasons). 1300 * 1301 * MPSAFE 1302 */ 1303 int 1304 cache_inval_vp_nonblock(struct vnode *vp) 1305 { 1306 struct namecache *ncp; 1307 struct namecache *next; 1308 1309 spin_lock_wr(&vp->v_spinlock); 1310 ncp = TAILQ_FIRST(&vp->v_namecache); 1311 if (ncp) 1312 _cache_hold(ncp); 1313 while (ncp) { 1314 /* loop entered with ncp held */ 1315 if ((next = TAILQ_NEXT(ncp, nc_vnode)) != NULL) 1316 _cache_hold(next); 1317 spin_unlock_wr(&vp->v_spinlock); 1318 if (_cache_lock_nonblock(ncp)) { 1319 _cache_drop(ncp); 1320 if (next) 1321 _cache_drop(next); 1322 goto done; 1323 } 1324 if (ncp->nc_vp != vp) { 1325 kprintf("Warning: cache_inval_vp: race-A detected on " 1326 "%s\n", ncp->nc_name); 1327 _cache_put(ncp); 1328 if (next) 1329 _cache_drop(next); 1330 goto done; 1331 } 1332 _cache_inval(ncp, 0); 1333 _cache_put(ncp); /* also releases reference */ 1334 ncp = next; 1335 spin_lock_wr(&vp->v_spinlock); 1336 if (ncp && ncp->nc_vp != vp) { 1337 spin_unlock_wr(&vp->v_spinlock); 1338 kprintf("Warning: cache_inval_vp: race-B detected on " 1339 "%s\n", ncp->nc_name); 1340 _cache_drop(ncp); 1341 goto done; 1342 } 1343 } 1344 spin_unlock_wr(&vp->v_spinlock); 1345 done: 1346 return(TAILQ_FIRST(&vp->v_namecache) != NULL); 1347 } 1348 1349 /* 1350 * The source ncp has been renamed to the target ncp. Both fncp and tncp 1351 * must be locked. The target ncp is destroyed (as a normal rename-over 1352 * would destroy the target file or directory). 1353 * 1354 * Because there may be references to the source ncp we cannot copy its 1355 * contents to the target. Instead the source ncp is relinked as the target 1356 * and the target ncp is removed from the namecache topology. 1357 * 1358 * MPSAFE 1359 */ 1360 void 1361 cache_rename(struct nchandle *fnch, struct nchandle *tnch) 1362 { 1363 struct namecache *fncp = fnch->ncp; 1364 struct namecache *tncp = tnch->ncp; 1365 struct namecache *tncp_par; 1366 struct nchash_head *nchpp; 1367 u_int32_t hash; 1368 char *oname; 1369 1370 /* 1371 * Rename fncp (unlink) 1372 */ 1373 _cache_unlink_parent(fncp); 1374 oname = fncp->nc_name; 1375 fncp->nc_name = tncp->nc_name; 1376 fncp->nc_nlen = tncp->nc_nlen; 1377 tncp_par = tncp->nc_parent; 1378 _cache_hold(tncp_par); 1379 _cache_lock(tncp_par); 1380 1381 /* 1382 * Rename fncp (relink) 1383 */ 1384 hash = fnv_32_buf(fncp->nc_name, fncp->nc_nlen, FNV1_32_INIT); 1385 hash = fnv_32_buf(&tncp_par, sizeof(tncp_par), hash); 1386 nchpp = NCHHASH(hash); 1387 1388 spin_lock_wr(&nchpp->spin); 1389 _cache_link_parent(fncp, tncp_par, nchpp); 1390 spin_unlock_wr(&nchpp->spin); 1391 1392 _cache_put(tncp_par); 1393 1394 /* 1395 * Get rid of the overwritten tncp (unlink) 1396 */ 1397 _cache_setunresolved(tncp); 1398 _cache_unlink_parent(tncp); 1399 tncp->nc_name = NULL; 1400 tncp->nc_nlen = 0; 1401 1402 if (oname) 1403 kfree(oname, M_VFSCACHE); 1404 } 1405 1406 /* 1407 * vget the vnode associated with the namecache entry. Resolve the namecache 1408 * entry if necessary. The passed ncp must be referenced and locked. 1409 * 1410 * lk_type may be LK_SHARED, LK_EXCLUSIVE. A ref'd, possibly locked 1411 * (depending on the passed lk_type) will be returned in *vpp with an error 1412 * of 0, or NULL will be returned in *vpp with a non-0 error code. The 1413 * most typical error is ENOENT, meaning that the ncp represents a negative 1414 * cache hit and there is no vnode to retrieve, but other errors can occur 1415 * too. 1416 * 1417 * The vget() can race a reclaim. If this occurs we re-resolve the 1418 * namecache entry. 1419 * 1420 * There are numerous places in the kernel where vget() is called on a 1421 * vnode while one or more of its namecache entries is locked. Releasing 1422 * a vnode never deadlocks against locked namecache entries (the vnode 1423 * will not get recycled while referenced ncp's exist). This means we 1424 * can safely acquire the vnode. In fact, we MUST NOT release the ncp 1425 * lock when acquiring the vp lock or we might cause a deadlock. 1426 * 1427 * MPSAFE 1428 */ 1429 int 1430 cache_vget(struct nchandle *nch, struct ucred *cred, 1431 int lk_type, struct vnode **vpp) 1432 { 1433 struct namecache *ncp; 1434 struct vnode *vp; 1435 int error; 1436 1437 ncp = nch->ncp; 1438 KKASSERT(ncp->nc_locktd == curthread); 1439 again: 1440 vp = NULL; 1441 if (ncp->nc_flag & NCF_UNRESOLVED) 1442 error = cache_resolve(nch, cred); 1443 else 1444 error = 0; 1445 1446 if (error == 0 && (vp = ncp->nc_vp) != NULL) { 1447 error = vget(vp, lk_type); 1448 if (error) { 1449 /* 1450 * VRECLAIM race 1451 */ 1452 if (error == ENOENT) { 1453 kprintf("Warning: vnode reclaim race detected " 1454 "in cache_vget on %p (%s)\n", 1455 vp, ncp->nc_name); 1456 _cache_setunresolved(ncp); 1457 goto again; 1458 } 1459 1460 /* 1461 * Not a reclaim race, some other error. 1462 */ 1463 KKASSERT(ncp->nc_vp == vp); 1464 vp = NULL; 1465 } else { 1466 KKASSERT(ncp->nc_vp == vp); 1467 KKASSERT((vp->v_flag & VRECLAIMED) == 0); 1468 } 1469 } 1470 if (error == 0 && vp == NULL) 1471 error = ENOENT; 1472 *vpp = vp; 1473 return(error); 1474 } 1475 1476 int 1477 cache_vref(struct nchandle *nch, struct ucred *cred, struct vnode **vpp) 1478 { 1479 struct namecache *ncp; 1480 struct vnode *vp; 1481 int error; 1482 1483 ncp = nch->ncp; 1484 KKASSERT(ncp->nc_locktd == curthread); 1485 again: 1486 vp = NULL; 1487 if (ncp->nc_flag & NCF_UNRESOLVED) 1488 error = cache_resolve(nch, cred); 1489 else 1490 error = 0; 1491 1492 if (error == 0 && (vp = ncp->nc_vp) != NULL) { 1493 error = vget(vp, LK_SHARED); 1494 if (error) { 1495 /* 1496 * VRECLAIM race 1497 */ 1498 if (error == ENOENT) { 1499 kprintf("Warning: vnode reclaim race detected " 1500 "in cache_vget on %p (%s)\n", 1501 vp, ncp->nc_name); 1502 _cache_setunresolved(ncp); 1503 goto again; 1504 } 1505 1506 /* 1507 * Not a reclaim race, some other error. 1508 */ 1509 KKASSERT(ncp->nc_vp == vp); 1510 vp = NULL; 1511 } else { 1512 KKASSERT(ncp->nc_vp == vp); 1513 KKASSERT((vp->v_flag & VRECLAIMED) == 0); 1514 /* caller does not want a lock */ 1515 vn_unlock(vp); 1516 } 1517 } 1518 if (error == 0 && vp == NULL) 1519 error = ENOENT; 1520 *vpp = vp; 1521 return(error); 1522 } 1523 1524 /* 1525 * Return a referenced vnode representing the parent directory of 1526 * ncp. 1527 * 1528 * Because the caller has locked the ncp it should not be possible for 1529 * the parent ncp to go away. However, the parent can unresolve its 1530 * dvp at any time so we must be able to acquire a lock on the parent 1531 * to safely access nc_vp. 1532 * 1533 * We have to leave par unlocked when vget()ing dvp to avoid a deadlock, 1534 * so use vhold()/vdrop() while holding the lock to prevent dvp from 1535 * getting destroyed. 1536 * 1537 * MPSAFE - Note vhold() is allowed when dvp has 0 refs if we hold a 1538 * lock on the ncp in question.. 1539 */ 1540 static struct vnode * 1541 cache_dvpref(struct namecache *ncp) 1542 { 1543 struct namecache *par; 1544 struct vnode *dvp; 1545 1546 dvp = NULL; 1547 if ((par = ncp->nc_parent) != NULL) { 1548 _cache_hold(par); 1549 _cache_lock(par); 1550 if ((par->nc_flag & NCF_UNRESOLVED) == 0) { 1551 if ((dvp = par->nc_vp) != NULL) 1552 vhold(dvp); 1553 } 1554 _cache_unlock(par); 1555 if (dvp) { 1556 if (vget(dvp, LK_SHARED) == 0) { 1557 vn_unlock(dvp); 1558 vdrop(dvp); 1559 /* return refd, unlocked dvp */ 1560 } else { 1561 vdrop(dvp); 1562 dvp = NULL; 1563 } 1564 } 1565 _cache_drop(par); 1566 } 1567 return(dvp); 1568 } 1569 1570 /* 1571 * Convert a directory vnode to a namecache record without any other 1572 * knowledge of the topology. This ONLY works with directory vnodes and 1573 * is ONLY used by the NFS server. dvp must be refd but unlocked, and the 1574 * returned ncp (if not NULL) will be held and unlocked. 1575 * 1576 * If 'makeit' is 0 and dvp has no existing namecache record, NULL is returned. 1577 * If 'makeit' is 1 we attempt to track-down and create the namecache topology 1578 * for dvp. This will fail only if the directory has been deleted out from 1579 * under the caller. 1580 * 1581 * Callers must always check for a NULL return no matter the value of 'makeit'. 1582 * 1583 * To avoid underflowing the kernel stack each recursive call increments 1584 * the makeit variable. 1585 */ 1586 1587 static int cache_inefficient_scan(struct nchandle *nch, struct ucred *cred, 1588 struct vnode *dvp, char *fakename); 1589 static int cache_fromdvp_try(struct vnode *dvp, struct ucred *cred, 1590 struct vnode **saved_dvp); 1591 1592 int 1593 cache_fromdvp(struct vnode *dvp, struct ucred *cred, int makeit, 1594 struct nchandle *nch) 1595 { 1596 struct vnode *saved_dvp; 1597 struct vnode *pvp; 1598 char *fakename; 1599 int error; 1600 1601 nch->ncp = NULL; 1602 nch->mount = dvp->v_mount; 1603 saved_dvp = NULL; 1604 fakename = NULL; 1605 1606 /* 1607 * Handle the makeit == 0 degenerate case 1608 */ 1609 if (makeit == 0) { 1610 spin_lock_wr(&dvp->v_spinlock); 1611 nch->ncp = TAILQ_FIRST(&dvp->v_namecache); 1612 if (nch->ncp) 1613 cache_hold(nch); 1614 spin_unlock_wr(&dvp->v_spinlock); 1615 } 1616 1617 /* 1618 * Loop until resolution, inside code will break out on error. 1619 */ 1620 while (makeit) { 1621 /* 1622 * Break out if we successfully acquire a working ncp. 1623 */ 1624 spin_lock_wr(&dvp->v_spinlock); 1625 nch->ncp = TAILQ_FIRST(&dvp->v_namecache); 1626 if (nch->ncp) { 1627 cache_hold(nch); 1628 spin_unlock_wr(&dvp->v_spinlock); 1629 break; 1630 } 1631 spin_unlock_wr(&dvp->v_spinlock); 1632 1633 /* 1634 * If dvp is the root of its filesystem it should already 1635 * have a namecache pointer associated with it as a side 1636 * effect of the mount, but it may have been disassociated. 1637 */ 1638 if (dvp->v_flag & VROOT) { 1639 nch->ncp = _cache_get(nch->mount->mnt_ncmountpt.ncp); 1640 error = cache_resolve_mp(nch->mount); 1641 _cache_put(nch->ncp); 1642 if (ncvp_debug) { 1643 kprintf("cache_fromdvp: resolve root of mount %p error %d", 1644 dvp->v_mount, error); 1645 } 1646 if (error) { 1647 if (ncvp_debug) 1648 kprintf(" failed\n"); 1649 nch->ncp = NULL; 1650 break; 1651 } 1652 if (ncvp_debug) 1653 kprintf(" succeeded\n"); 1654 continue; 1655 } 1656 1657 /* 1658 * If we are recursed too deeply resort to an O(n^2) 1659 * algorithm to resolve the namecache topology. The 1660 * resolved pvp is left referenced in saved_dvp to 1661 * prevent the tree from being destroyed while we loop. 1662 */ 1663 if (makeit > 20) { 1664 error = cache_fromdvp_try(dvp, cred, &saved_dvp); 1665 if (error) { 1666 kprintf("lookupdotdot(longpath) failed %d " 1667 "dvp %p\n", error, dvp); 1668 nch->ncp = NULL; 1669 break; 1670 } 1671 continue; 1672 } 1673 1674 /* 1675 * Get the parent directory and resolve its ncp. 1676 */ 1677 if (fakename) { 1678 kfree(fakename, M_TEMP); 1679 fakename = NULL; 1680 } 1681 error = vop_nlookupdotdot(*dvp->v_ops, dvp, &pvp, cred, 1682 &fakename); 1683 if (error) { 1684 kprintf("lookupdotdot failed %d dvp %p\n", error, dvp); 1685 break; 1686 } 1687 vn_unlock(pvp); 1688 1689 /* 1690 * Reuse makeit as a recursion depth counter. On success 1691 * nch will be fully referenced. 1692 */ 1693 cache_fromdvp(pvp, cred, makeit + 1, nch); 1694 vrele(pvp); 1695 if (nch->ncp == NULL) 1696 break; 1697 1698 /* 1699 * Do an inefficient scan of pvp (embodied by ncp) to look 1700 * for dvp. This will create a namecache record for dvp on 1701 * success. We loop up to recheck on success. 1702 * 1703 * ncp and dvp are both held but not locked. 1704 */ 1705 error = cache_inefficient_scan(nch, cred, dvp, fakename); 1706 if (error) { 1707 kprintf("cache_fromdvp: scan %p (%s) failed on dvp=%p\n", 1708 pvp, nch->ncp->nc_name, dvp); 1709 cache_drop(nch); 1710 /* nch was NULLed out, reload mount */ 1711 nch->mount = dvp->v_mount; 1712 break; 1713 } 1714 if (ncvp_debug) { 1715 kprintf("cache_fromdvp: scan %p (%s) succeeded\n", 1716 pvp, nch->ncp->nc_name); 1717 } 1718 cache_drop(nch); 1719 /* nch was NULLed out, reload mount */ 1720 nch->mount = dvp->v_mount; 1721 } 1722 1723 /* 1724 * If nch->ncp is non-NULL it will have been held already. 1725 */ 1726 if (fakename) 1727 kfree(fakename, M_TEMP); 1728 if (saved_dvp) 1729 vrele(saved_dvp); 1730 if (nch->ncp) 1731 return (0); 1732 return (EINVAL); 1733 } 1734 1735 /* 1736 * Go up the chain of parent directories until we find something 1737 * we can resolve into the namecache. This is very inefficient. 1738 */ 1739 static 1740 int 1741 cache_fromdvp_try(struct vnode *dvp, struct ucred *cred, 1742 struct vnode **saved_dvp) 1743 { 1744 struct nchandle nch; 1745 struct vnode *pvp; 1746 int error; 1747 static time_t last_fromdvp_report; 1748 char *fakename; 1749 1750 /* 1751 * Loop getting the parent directory vnode until we get something we 1752 * can resolve in the namecache. 1753 */ 1754 vref(dvp); 1755 nch.mount = dvp->v_mount; 1756 nch.ncp = NULL; 1757 fakename = NULL; 1758 1759 for (;;) { 1760 if (fakename) { 1761 kfree(fakename, M_TEMP); 1762 fakename = NULL; 1763 } 1764 error = vop_nlookupdotdot(*dvp->v_ops, dvp, &pvp, cred, 1765 &fakename); 1766 if (error) { 1767 vrele(dvp); 1768 break; 1769 } 1770 vn_unlock(pvp); 1771 spin_lock_wr(&pvp->v_spinlock); 1772 if ((nch.ncp = TAILQ_FIRST(&pvp->v_namecache)) != NULL) { 1773 _cache_hold(nch.ncp); 1774 spin_unlock_wr(&pvp->v_spinlock); 1775 vrele(pvp); 1776 break; 1777 } 1778 spin_unlock_wr(&pvp->v_spinlock); 1779 if (pvp->v_flag & VROOT) { 1780 nch.ncp = _cache_get(pvp->v_mount->mnt_ncmountpt.ncp); 1781 error = cache_resolve_mp(nch.mount); 1782 _cache_unlock(nch.ncp); 1783 vrele(pvp); 1784 if (error) { 1785 _cache_drop(nch.ncp); 1786 nch.ncp = NULL; 1787 vrele(dvp); 1788 } 1789 break; 1790 } 1791 vrele(dvp); 1792 dvp = pvp; 1793 } 1794 if (error == 0) { 1795 if (last_fromdvp_report != time_second) { 1796 last_fromdvp_report = time_second; 1797 kprintf("Warning: extremely inefficient path " 1798 "resolution on %s\n", 1799 nch.ncp->nc_name); 1800 } 1801 error = cache_inefficient_scan(&nch, cred, dvp, fakename); 1802 1803 /* 1804 * Hopefully dvp now has a namecache record associated with 1805 * it. Leave it referenced to prevent the kernel from 1806 * recycling the vnode. Otherwise extremely long directory 1807 * paths could result in endless recycling. 1808 */ 1809 if (*saved_dvp) 1810 vrele(*saved_dvp); 1811 *saved_dvp = dvp; 1812 _cache_drop(nch.ncp); 1813 } 1814 if (fakename) 1815 kfree(fakename, M_TEMP); 1816 return (error); 1817 } 1818 1819 /* 1820 * Do an inefficient scan of the directory represented by ncp looking for 1821 * the directory vnode dvp. ncp must be held but not locked on entry and 1822 * will be held on return. dvp must be refd but not locked on entry and 1823 * will remain refd on return. 1824 * 1825 * Why do this at all? Well, due to its stateless nature the NFS server 1826 * converts file handles directly to vnodes without necessarily going through 1827 * the namecache ops that would otherwise create the namecache topology 1828 * leading to the vnode. We could either (1) Change the namecache algorithms 1829 * to allow disconnect namecache records that are re-merged opportunistically, 1830 * or (2) Make the NFS server backtrack and scan to recover a connected 1831 * namecache topology in order to then be able to issue new API lookups. 1832 * 1833 * It turns out that (1) is a huge mess. It takes a nice clean set of 1834 * namecache algorithms and introduces a lot of complication in every subsystem 1835 * that calls into the namecache to deal with the re-merge case, especially 1836 * since we are using the namecache to placehold negative lookups and the 1837 * vnode might not be immediately assigned. (2) is certainly far less 1838 * efficient then (1), but since we are only talking about directories here 1839 * (which are likely to remain cached), the case does not actually run all 1840 * that often and has the supreme advantage of not polluting the namecache 1841 * algorithms. 1842 * 1843 * If a fakename is supplied just construct a namecache entry using the 1844 * fake name. 1845 */ 1846 static int 1847 cache_inefficient_scan(struct nchandle *nch, struct ucred *cred, 1848 struct vnode *dvp, char *fakename) 1849 { 1850 struct nlcomponent nlc; 1851 struct nchandle rncp; 1852 struct dirent *den; 1853 struct vnode *pvp; 1854 struct vattr vat; 1855 struct iovec iov; 1856 struct uio uio; 1857 int blksize; 1858 int eofflag; 1859 int bytes; 1860 char *rbuf; 1861 int error; 1862 1863 vat.va_blocksize = 0; 1864 if ((error = VOP_GETATTR(dvp, &vat)) != 0) 1865 return (error); 1866 cache_lock(nch); 1867 error = cache_vref(nch, cred, &pvp); 1868 cache_unlock(nch); 1869 if (error) 1870 return (error); 1871 if (ncvp_debug) { 1872 kprintf("inefficient_scan: directory iosize %ld " 1873 "vattr fileid = %lld\n", 1874 vat.va_blocksize, 1875 (long long)vat.va_fileid); 1876 } 1877 1878 /* 1879 * Use the supplied fakename if not NULL. Fake names are typically 1880 * not in the actual filesystem hierarchy. This is used by HAMMER 1881 * to glue @@timestamp recursions together. 1882 */ 1883 if (fakename) { 1884 nlc.nlc_nameptr = fakename; 1885 nlc.nlc_namelen = strlen(fakename); 1886 rncp = cache_nlookup(nch, &nlc); 1887 goto done; 1888 } 1889 1890 if ((blksize = vat.va_blocksize) == 0) 1891 blksize = DEV_BSIZE; 1892 rbuf = kmalloc(blksize, M_TEMP, M_WAITOK); 1893 rncp.ncp = NULL; 1894 1895 eofflag = 0; 1896 uio.uio_offset = 0; 1897 again: 1898 iov.iov_base = rbuf; 1899 iov.iov_len = blksize; 1900 uio.uio_iov = &iov; 1901 uio.uio_iovcnt = 1; 1902 uio.uio_resid = blksize; 1903 uio.uio_segflg = UIO_SYSSPACE; 1904 uio.uio_rw = UIO_READ; 1905 uio.uio_td = curthread; 1906 1907 if (ncvp_debug >= 2) 1908 kprintf("cache_inefficient_scan: readdir @ %08x\n", (int)uio.uio_offset); 1909 error = VOP_READDIR(pvp, &uio, cred, &eofflag, NULL, NULL); 1910 if (error == 0) { 1911 den = (struct dirent *)rbuf; 1912 bytes = blksize - uio.uio_resid; 1913 1914 while (bytes > 0) { 1915 if (ncvp_debug >= 2) { 1916 kprintf("cache_inefficient_scan: %*.*s\n", 1917 den->d_namlen, den->d_namlen, 1918 den->d_name); 1919 } 1920 if (den->d_type != DT_WHT && 1921 den->d_ino == vat.va_fileid) { 1922 if (ncvp_debug) { 1923 kprintf("cache_inefficient_scan: " 1924 "MATCHED inode %lld path %s/%*.*s\n", 1925 (long long)vat.va_fileid, 1926 nch->ncp->nc_name, 1927 den->d_namlen, den->d_namlen, 1928 den->d_name); 1929 } 1930 nlc.nlc_nameptr = den->d_name; 1931 nlc.nlc_namelen = den->d_namlen; 1932 rncp = cache_nlookup(nch, &nlc); 1933 KKASSERT(rncp.ncp != NULL); 1934 break; 1935 } 1936 bytes -= _DIRENT_DIRSIZ(den); 1937 den = _DIRENT_NEXT(den); 1938 } 1939 if (rncp.ncp == NULL && eofflag == 0 && uio.uio_resid != blksize) 1940 goto again; 1941 } 1942 kfree(rbuf, M_TEMP); 1943 done: 1944 vrele(pvp); 1945 if (rncp.ncp) { 1946 if (rncp.ncp->nc_flag & NCF_UNRESOLVED) { 1947 _cache_setvp(rncp.mount, rncp.ncp, dvp); 1948 if (ncvp_debug >= 2) { 1949 kprintf("cache_inefficient_scan: setvp %s/%s = %p\n", 1950 nch->ncp->nc_name, rncp.ncp->nc_name, dvp); 1951 } 1952 } else { 1953 if (ncvp_debug >= 2) { 1954 kprintf("cache_inefficient_scan: setvp %s/%s already set %p/%p\n", 1955 nch->ncp->nc_name, rncp.ncp->nc_name, dvp, 1956 rncp.ncp->nc_vp); 1957 } 1958 } 1959 if (rncp.ncp->nc_vp == NULL) 1960 error = rncp.ncp->nc_error; 1961 /* 1962 * Release rncp after a successful nlookup. rncp was fully 1963 * referenced. 1964 */ 1965 cache_put(&rncp); 1966 } else { 1967 kprintf("cache_inefficient_scan: dvp %p NOT FOUND in %s\n", 1968 dvp, nch->ncp->nc_name); 1969 error = ENOENT; 1970 } 1971 return (error); 1972 } 1973 1974 /* 1975 * Zap a namecache entry. The ncp is unconditionally set to an unresolved 1976 * state, which disassociates it from its vnode or ncneglist. 1977 * 1978 * Then, if there are no additional references to the ncp and no children, 1979 * the ncp is removed from the topology and destroyed. 1980 * 1981 * References and/or children may exist if the ncp is in the middle of the 1982 * topology, preventing the ncp from being destroyed. 1983 * 1984 * This function must be called with the ncp held and locked and will unlock 1985 * and drop it during zapping. 1986 * 1987 * If nonblock is non-zero and the parent ncp cannot be locked we give up. 1988 * This case can occur in the cache_drop() path. 1989 * 1990 * This function may returned a held (but NOT locked) parent node which the 1991 * caller must drop. We do this so _cache_drop() can loop, to avoid 1992 * blowing out the kernel stack. 1993 * 1994 * WARNING! For MPSAFE operation this routine must acquire up to three 1995 * spin locks to be able to safely test nc_refs. Lock order is 1996 * very important. 1997 * 1998 * hash spinlock if on hash list 1999 * parent spinlock if child of parent 2000 * (the ncp is unresolved so there is no vnode association) 2001 */ 2002 static struct namecache * 2003 cache_zap(struct namecache *ncp, int nonblock) 2004 { 2005 struct namecache *par; 2006 struct vnode *dropvp; 2007 int refs; 2008 2009 /* 2010 * Disassociate the vnode or negative cache ref and set NCF_UNRESOLVED. 2011 */ 2012 _cache_setunresolved(ncp); 2013 2014 /* 2015 * Try to scrap the entry and possibly tail-recurse on its parent. 2016 * We only scrap unref'd (other then our ref) unresolved entries, 2017 * we do not scrap 'live' entries. 2018 * 2019 * Note that once the spinlocks are acquired if nc_refs == 1 no 2020 * other references are possible. If it isn't, however, we have 2021 * to decrement but also be sure to avoid a 1->0 transition. 2022 */ 2023 KKASSERT(ncp->nc_flag & NCF_UNRESOLVED); 2024 KKASSERT(ncp->nc_refs > 0); 2025 2026 /* 2027 * Acquire locks. Note that the parent can't go away while we hold 2028 * a child locked. 2029 */ 2030 if ((par = ncp->nc_parent) != NULL) { 2031 if (nonblock) { 2032 for (;;) { 2033 if (_cache_lock_nonblock(par) == 0) 2034 break; 2035 refs = ncp->nc_refs; 2036 ncp->nc_flag |= NCF_DEFEREDZAP; 2037 ++numdefered; /* MP race ok */ 2038 if (atomic_cmpset_int(&ncp->nc_refs, 2039 refs, refs - 1)) { 2040 _cache_unlock(ncp); 2041 return(NULL); 2042 } 2043 cpu_pause(); 2044 } 2045 _cache_hold(par); 2046 } else { 2047 _cache_hold(par); 2048 _cache_lock(par); 2049 } 2050 spin_lock_wr(&ncp->nc_head->spin); 2051 } 2052 2053 /* 2054 * If someone other then us has a ref or we have children 2055 * we cannot zap the entry. The 1->0 transition and any 2056 * further list operation is protected by the spinlocks 2057 * we have acquired but other transitions are not. 2058 */ 2059 for (;;) { 2060 refs = ncp->nc_refs; 2061 if (refs == 1 && TAILQ_EMPTY(&ncp->nc_list)) 2062 break; 2063 if (atomic_cmpset_int(&ncp->nc_refs, refs, refs - 1)) { 2064 if (par) { 2065 spin_unlock_wr(&ncp->nc_head->spin); 2066 _cache_put(par); 2067 } 2068 _cache_unlock(ncp); 2069 return(NULL); 2070 } 2071 cpu_pause(); 2072 } 2073 2074 /* 2075 * We are the only ref and with the spinlocks held no further 2076 * refs can be acquired by others. 2077 * 2078 * Remove us from the hash list and parent list. We have to 2079 * drop a ref on the parent's vp if the parent's list becomes 2080 * empty. 2081 */ 2082 dropvp = NULL; 2083 if (par) { 2084 struct nchash_head *nchpp = ncp->nc_head; 2085 2086 KKASSERT(nchpp != NULL); 2087 LIST_REMOVE(ncp, nc_hash); 2088 TAILQ_REMOVE(&par->nc_list, ncp, nc_entry); 2089 if (par->nc_vp && TAILQ_EMPTY(&par->nc_list)) 2090 dropvp = par->nc_vp; 2091 ncp->nc_head = NULL; 2092 ncp->nc_parent = NULL; 2093 spin_unlock_wr(&nchpp->spin); 2094 _cache_unlock(par); 2095 } else { 2096 KKASSERT(ncp->nc_head == NULL); 2097 } 2098 2099 /* 2100 * ncp should not have picked up any refs. Physically 2101 * destroy the ncp. 2102 */ 2103 KKASSERT(ncp->nc_refs == 1); 2104 /* _cache_unlock(ncp) not required */ 2105 ncp->nc_refs = -1; /* safety */ 2106 if (ncp->nc_name) 2107 kfree(ncp->nc_name, M_VFSCACHE); 2108 kfree(ncp, M_VFSCACHE); 2109 2110 /* 2111 * Delayed drop (we had to release our spinlocks) 2112 * 2113 * The refed parent (if not NULL) must be dropped. The 2114 * caller is responsible for looping. 2115 */ 2116 if (dropvp) 2117 vdrop(dropvp); 2118 return(par); 2119 } 2120 2121 /* 2122 * Clean up dangling negative cache and defered-drop entries in the 2123 * namecache. 2124 */ 2125 static enum { CHI_LOW, CHI_HIGH } cache_hysteresis_state = CHI_LOW; 2126 2127 void 2128 cache_hysteresis(void) 2129 { 2130 /* 2131 * Don't cache too many negative hits. We use hysteresis to reduce 2132 * the impact on the critical path. 2133 */ 2134 switch(cache_hysteresis_state) { 2135 case CHI_LOW: 2136 if (numneg > MINNEG && numneg * ncnegfactor > numcache) { 2137 _cache_cleanneg(10); 2138 cache_hysteresis_state = CHI_HIGH; 2139 } 2140 break; 2141 case CHI_HIGH: 2142 if (numneg > MINNEG * 9 / 10 && 2143 numneg * ncnegfactor * 9 / 10 > numcache 2144 ) { 2145 _cache_cleanneg(10); 2146 } else { 2147 cache_hysteresis_state = CHI_LOW; 2148 } 2149 break; 2150 } 2151 2152 /* 2153 * Clean out dangling defered-zap ncps which could not 2154 * be cleanly dropped if too many build up. Note 2155 * that numdefered is not an exact number as such ncps 2156 * can be reused and the counter is not handled in a MP 2157 * safe manner by design. 2158 */ 2159 if (numdefered * ncnegfactor > numcache) { 2160 _cache_cleandefered(); 2161 } 2162 } 2163 2164 /* 2165 * NEW NAMECACHE LOOKUP API 2166 * 2167 * Lookup an entry in the namecache. The passed par_nch must be referenced 2168 * and unlocked. A referenced and locked nchandle with a non-NULL nch.ncp 2169 * is ALWAYS returned, eve if the supplied component is illegal. 2170 * 2171 * The resulting namecache entry should be returned to the system with 2172 * cache_put() or cache_unlock() + cache_drop(). 2173 * 2174 * namecache locks are recursive but care must be taken to avoid lock order 2175 * reversals (hence why the passed par_nch must be unlocked). Locking 2176 * rules are to order for parent traversals, not for child traversals. 2177 * 2178 * Nobody else will be able to manipulate the associated namespace (e.g. 2179 * create, delete, rename, rename-target) until the caller unlocks the 2180 * entry. 2181 * 2182 * The returned entry will be in one of three states: positive hit (non-null 2183 * vnode), negative hit (null vnode), or unresolved (NCF_UNRESOLVED is set). 2184 * Unresolved entries must be resolved through the filesystem to associate the 2185 * vnode and/or determine whether a positive or negative hit has occured. 2186 * 2187 * It is not necessary to lock a directory in order to lock namespace under 2188 * that directory. In fact, it is explicitly not allowed to do that. A 2189 * directory is typically only locked when being created, renamed, or 2190 * destroyed. 2191 * 2192 * The directory (par) may be unresolved, in which case any returned child 2193 * will likely also be marked unresolved. Likely but not guarenteed. Since 2194 * the filesystem lookup requires a resolved directory vnode the caller is 2195 * responsible for resolving the namecache chain top-down. This API 2196 * specifically allows whole chains to be created in an unresolved state. 2197 */ 2198 struct nchandle 2199 cache_nlookup(struct nchandle *par_nch, struct nlcomponent *nlc) 2200 { 2201 struct nchandle nch; 2202 struct namecache *ncp; 2203 struct namecache *new_ncp; 2204 struct nchash_head *nchpp; 2205 struct mount *mp; 2206 u_int32_t hash; 2207 globaldata_t gd; 2208 int par_locked; 2209 2210 numcalls++; 2211 gd = mycpu; 2212 mp = par_nch->mount; 2213 par_locked = 0; 2214 2215 /* 2216 * This is a good time to call it, no ncp's are locked by 2217 * the caller or us. 2218 */ 2219 cache_hysteresis(); 2220 2221 /* 2222 * Try to locate an existing entry 2223 */ 2224 hash = fnv_32_buf(nlc->nlc_nameptr, nlc->nlc_namelen, FNV1_32_INIT); 2225 hash = fnv_32_buf(&par_nch->ncp, sizeof(par_nch->ncp), hash); 2226 new_ncp = NULL; 2227 nchpp = NCHHASH(hash); 2228 restart: 2229 spin_lock_wr(&nchpp->spin); 2230 LIST_FOREACH(ncp, &nchpp->list, nc_hash) { 2231 numchecks++; 2232 2233 /* 2234 * Break out if we find a matching entry. Note that 2235 * UNRESOLVED entries may match, but DESTROYED entries 2236 * do not. 2237 */ 2238 if (ncp->nc_parent == par_nch->ncp && 2239 ncp->nc_nlen == nlc->nlc_namelen && 2240 bcmp(ncp->nc_name, nlc->nlc_nameptr, ncp->nc_nlen) == 0 && 2241 (ncp->nc_flag & NCF_DESTROYED) == 0 2242 ) { 2243 _cache_hold(ncp); 2244 spin_unlock_wr(&nchpp->spin); 2245 if (par_locked) { 2246 _cache_unlock(par_nch->ncp); 2247 par_locked = 0; 2248 } 2249 if (_cache_lock_special(ncp) == 0) { 2250 _cache_auto_unresolve(mp, ncp); 2251 if (new_ncp) 2252 _cache_free(new_ncp); 2253 goto found; 2254 } 2255 _cache_get(ncp); 2256 _cache_put(ncp); 2257 _cache_drop(ncp); 2258 goto restart; 2259 } 2260 } 2261 2262 /* 2263 * We failed to locate an entry, create a new entry and add it to 2264 * the cache. The parent ncp must also be locked so we 2265 * can link into it. 2266 * 2267 * We have to relookup after possibly blocking in kmalloc or 2268 * when locking par_nch. 2269 * 2270 * NOTE: nlc_namelen can be 0 and nlc_nameptr NULL as a special 2271 * mount case, in which case nc_name will be NULL. 2272 */ 2273 if (new_ncp == NULL) { 2274 spin_unlock_wr(&nchpp->spin); 2275 new_ncp = cache_alloc(nlc->nlc_namelen); 2276 if (nlc->nlc_namelen) { 2277 bcopy(nlc->nlc_nameptr, new_ncp->nc_name, 2278 nlc->nlc_namelen); 2279 new_ncp->nc_name[nlc->nlc_namelen] = 0; 2280 } 2281 goto restart; 2282 } 2283 if (par_locked == 0) { 2284 spin_unlock_wr(&nchpp->spin); 2285 _cache_lock(par_nch->ncp); 2286 par_locked = 1; 2287 goto restart; 2288 } 2289 2290 /* 2291 * WARNING! We still hold the spinlock. We have to set the hash 2292 * table entry atomically. 2293 */ 2294 ncp = new_ncp; 2295 _cache_link_parent(ncp, par_nch->ncp, nchpp); 2296 spin_unlock_wr(&nchpp->spin); 2297 _cache_unlock(par_nch->ncp); 2298 /* par_locked = 0 - not used */ 2299 found: 2300 /* 2301 * stats and namecache size management 2302 */ 2303 if (ncp->nc_flag & NCF_UNRESOLVED) 2304 ++gd->gd_nchstats->ncs_miss; 2305 else if (ncp->nc_vp) 2306 ++gd->gd_nchstats->ncs_goodhits; 2307 else 2308 ++gd->gd_nchstats->ncs_neghits; 2309 nch.mount = mp; 2310 nch.ncp = ncp; 2311 atomic_add_int(&nch.mount->mnt_refs, 1); 2312 return(nch); 2313 } 2314 2315 /* 2316 * This is a non-blocking verison of cache_nlookup() used by 2317 * nfs_readdirplusrpc_uio(). It can fail for any reason and 2318 * will return nch.ncp == NULL in that case. 2319 */ 2320 struct nchandle 2321 cache_nlookup_nonblock(struct nchandle *par_nch, struct nlcomponent *nlc) 2322 { 2323 struct nchandle nch; 2324 struct namecache *ncp; 2325 struct namecache *new_ncp; 2326 struct nchash_head *nchpp; 2327 struct mount *mp; 2328 u_int32_t hash; 2329 globaldata_t gd; 2330 int par_locked; 2331 2332 numcalls++; 2333 gd = mycpu; 2334 mp = par_nch->mount; 2335 par_locked = 0; 2336 2337 /* 2338 * Try to locate an existing entry 2339 */ 2340 hash = fnv_32_buf(nlc->nlc_nameptr, nlc->nlc_namelen, FNV1_32_INIT); 2341 hash = fnv_32_buf(&par_nch->ncp, sizeof(par_nch->ncp), hash); 2342 new_ncp = NULL; 2343 nchpp = NCHHASH(hash); 2344 restart: 2345 spin_lock_wr(&nchpp->spin); 2346 LIST_FOREACH(ncp, &nchpp->list, nc_hash) { 2347 numchecks++; 2348 2349 /* 2350 * Break out if we find a matching entry. Note that 2351 * UNRESOLVED entries may match, but DESTROYED entries 2352 * do not. 2353 */ 2354 if (ncp->nc_parent == par_nch->ncp && 2355 ncp->nc_nlen == nlc->nlc_namelen && 2356 bcmp(ncp->nc_name, nlc->nlc_nameptr, ncp->nc_nlen) == 0 && 2357 (ncp->nc_flag & NCF_DESTROYED) == 0 2358 ) { 2359 _cache_hold(ncp); 2360 spin_unlock_wr(&nchpp->spin); 2361 if (par_locked) { 2362 _cache_unlock(par_nch->ncp); 2363 par_locked = 0; 2364 } 2365 if (_cache_lock_special(ncp) == 0) { 2366 _cache_auto_unresolve(mp, ncp); 2367 if (new_ncp) { 2368 _cache_free(new_ncp); 2369 new_ncp = NULL; 2370 } 2371 goto found; 2372 } 2373 _cache_drop(ncp); 2374 goto failed; 2375 } 2376 } 2377 2378 /* 2379 * We failed to locate an entry, create a new entry and add it to 2380 * the cache. The parent ncp must also be locked so we 2381 * can link into it. 2382 * 2383 * We have to relookup after possibly blocking in kmalloc or 2384 * when locking par_nch. 2385 * 2386 * NOTE: nlc_namelen can be 0 and nlc_nameptr NULL as a special 2387 * mount case, in which case nc_name will be NULL. 2388 */ 2389 if (new_ncp == NULL) { 2390 spin_unlock_wr(&nchpp->spin); 2391 new_ncp = cache_alloc(nlc->nlc_namelen); 2392 if (nlc->nlc_namelen) { 2393 bcopy(nlc->nlc_nameptr, new_ncp->nc_name, 2394 nlc->nlc_namelen); 2395 new_ncp->nc_name[nlc->nlc_namelen] = 0; 2396 } 2397 goto restart; 2398 } 2399 if (par_locked == 0) { 2400 spin_unlock_wr(&nchpp->spin); 2401 if (_cache_lock_nonblock(par_nch->ncp) == 0) { 2402 par_locked = 1; 2403 goto restart; 2404 } 2405 goto failed; 2406 } 2407 2408 /* 2409 * WARNING! We still hold the spinlock. We have to set the hash 2410 * table entry atomically. 2411 */ 2412 ncp = new_ncp; 2413 _cache_link_parent(ncp, par_nch->ncp, nchpp); 2414 spin_unlock_wr(&nchpp->spin); 2415 _cache_unlock(par_nch->ncp); 2416 /* par_locked = 0 - not used */ 2417 found: 2418 /* 2419 * stats and namecache size management 2420 */ 2421 if (ncp->nc_flag & NCF_UNRESOLVED) 2422 ++gd->gd_nchstats->ncs_miss; 2423 else if (ncp->nc_vp) 2424 ++gd->gd_nchstats->ncs_goodhits; 2425 else 2426 ++gd->gd_nchstats->ncs_neghits; 2427 nch.mount = mp; 2428 nch.ncp = ncp; 2429 atomic_add_int(&nch.mount->mnt_refs, 1); 2430 return(nch); 2431 failed: 2432 if (new_ncp) { 2433 _cache_free(new_ncp); 2434 new_ncp = NULL; 2435 } 2436 nch.mount = NULL; 2437 nch.ncp = NULL; 2438 return(nch); 2439 } 2440 2441 /* 2442 * The namecache entry is marked as being used as a mount point. 2443 * Locate the mount if it is visible to the caller. 2444 */ 2445 struct findmount_info { 2446 struct mount *result; 2447 struct mount *nch_mount; 2448 struct namecache *nch_ncp; 2449 }; 2450 2451 static 2452 int 2453 cache_findmount_callback(struct mount *mp, void *data) 2454 { 2455 struct findmount_info *info = data; 2456 2457 /* 2458 * Check the mount's mounted-on point against the passed nch. 2459 */ 2460 if (mp->mnt_ncmounton.mount == info->nch_mount && 2461 mp->mnt_ncmounton.ncp == info->nch_ncp 2462 ) { 2463 info->result = mp; 2464 return(-1); 2465 } 2466 return(0); 2467 } 2468 2469 struct mount * 2470 cache_findmount(struct nchandle *nch) 2471 { 2472 struct findmount_info info; 2473 2474 info.result = NULL; 2475 info.nch_mount = nch->mount; 2476 info.nch_ncp = nch->ncp; 2477 mountlist_scan(cache_findmount_callback, &info, 2478 MNTSCAN_FORWARD|MNTSCAN_NOBUSY); 2479 return(info.result); 2480 } 2481 2482 /* 2483 * Resolve an unresolved namecache entry, generally by looking it up. 2484 * The passed ncp must be locked and refd. 2485 * 2486 * Theoretically since a vnode cannot be recycled while held, and since 2487 * the nc_parent chain holds its vnode as long as children exist, the 2488 * direct parent of the cache entry we are trying to resolve should 2489 * have a valid vnode. If not then generate an error that we can 2490 * determine is related to a resolver bug. 2491 * 2492 * However, if a vnode was in the middle of a recyclement when the NCP 2493 * got locked, ncp->nc_vp might point to a vnode that is about to become 2494 * invalid. cache_resolve() handles this case by unresolving the entry 2495 * and then re-resolving it. 2496 * 2497 * Note that successful resolution does not necessarily return an error 2498 * code of 0. If the ncp resolves to a negative cache hit then ENOENT 2499 * will be returned. 2500 * 2501 * MPSAFE 2502 */ 2503 int 2504 cache_resolve(struct nchandle *nch, struct ucred *cred) 2505 { 2506 struct namecache *par_tmp; 2507 struct namecache *par; 2508 struct namecache *ncp; 2509 struct nchandle nctmp; 2510 struct mount *mp; 2511 struct vnode *dvp; 2512 int error; 2513 2514 ncp = nch->ncp; 2515 mp = nch->mount; 2516 restart: 2517 /* 2518 * If the ncp is already resolved we have nothing to do. However, 2519 * we do want to guarentee that a usable vnode is returned when 2520 * a vnode is present, so make sure it hasn't been reclaimed. 2521 */ 2522 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) { 2523 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) 2524 _cache_setunresolved(ncp); 2525 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) 2526 return (ncp->nc_error); 2527 } 2528 2529 /* 2530 * Mount points need special handling because the parent does not 2531 * belong to the same filesystem as the ncp. 2532 */ 2533 if (ncp == mp->mnt_ncmountpt.ncp) 2534 return (cache_resolve_mp(mp)); 2535 2536 /* 2537 * We expect an unbroken chain of ncps to at least the mount point, 2538 * and even all the way to root (but this code doesn't have to go 2539 * past the mount point). 2540 */ 2541 if (ncp->nc_parent == NULL) { 2542 kprintf("EXDEV case 1 %p %*.*s\n", ncp, 2543 ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name); 2544 ncp->nc_error = EXDEV; 2545 return(ncp->nc_error); 2546 } 2547 2548 /* 2549 * The vp's of the parent directories in the chain are held via vhold() 2550 * due to the existance of the child, and should not disappear. 2551 * However, there are cases where they can disappear: 2552 * 2553 * - due to filesystem I/O errors. 2554 * - due to NFS being stupid about tracking the namespace and 2555 * destroys the namespace for entire directories quite often. 2556 * - due to forced unmounts. 2557 * - due to an rmdir (parent will be marked DESTROYED) 2558 * 2559 * When this occurs we have to track the chain backwards and resolve 2560 * it, looping until the resolver catches up to the current node. We 2561 * could recurse here but we might run ourselves out of kernel stack 2562 * so we do it in a more painful manner. This situation really should 2563 * not occur all that often, or if it does not have to go back too 2564 * many nodes to resolve the ncp. 2565 */ 2566 while ((dvp = cache_dvpref(ncp)) == NULL) { 2567 /* 2568 * This case can occur if a process is CD'd into a 2569 * directory which is then rmdir'd. If the parent is marked 2570 * destroyed there is no point trying to resolve it. 2571 */ 2572 if (ncp->nc_parent->nc_flag & NCF_DESTROYED) 2573 return(ENOENT); 2574 par = ncp->nc_parent; 2575 _cache_hold(par); 2576 _cache_lock(par); 2577 while ((par_tmp = par->nc_parent) != NULL && 2578 par_tmp->nc_vp == NULL) { 2579 _cache_hold(par_tmp); 2580 _cache_lock(par_tmp); 2581 _cache_put(par); 2582 par = par_tmp; 2583 } 2584 if (par->nc_parent == NULL) { 2585 kprintf("EXDEV case 2 %*.*s\n", 2586 par->nc_nlen, par->nc_nlen, par->nc_name); 2587 _cache_put(par); 2588 return (EXDEV); 2589 } 2590 kprintf("[diagnostic] cache_resolve: had to recurse on %*.*s\n", 2591 par->nc_nlen, par->nc_nlen, par->nc_name); 2592 /* 2593 * The parent is not set in stone, ref and lock it to prevent 2594 * it from disappearing. Also note that due to renames it 2595 * is possible for our ncp to move and for par to no longer 2596 * be one of its parents. We resolve it anyway, the loop 2597 * will handle any moves. 2598 */ 2599 _cache_get(par); /* additional hold/lock */ 2600 _cache_put(par); /* from earlier hold/lock */ 2601 if (par == nch->mount->mnt_ncmountpt.ncp) { 2602 cache_resolve_mp(nch->mount); 2603 } else if ((dvp = cache_dvpref(par)) == NULL) { 2604 kprintf("[diagnostic] cache_resolve: raced on %*.*s\n", par->nc_nlen, par->nc_nlen, par->nc_name); 2605 _cache_put(par); 2606 continue; 2607 } else { 2608 if (par->nc_flag & NCF_UNRESOLVED) { 2609 nctmp.mount = mp; 2610 nctmp.ncp = par; 2611 par->nc_error = VOP_NRESOLVE(&nctmp, dvp, cred); 2612 } 2613 vrele(dvp); 2614 } 2615 if ((error = par->nc_error) != 0) { 2616 if (par->nc_error != EAGAIN) { 2617 kprintf("EXDEV case 3 %*.*s error %d\n", 2618 par->nc_nlen, par->nc_nlen, par->nc_name, 2619 par->nc_error); 2620 _cache_put(par); 2621 return(error); 2622 } 2623 kprintf("[diagnostic] cache_resolve: EAGAIN par %p %*.*s\n", 2624 par, par->nc_nlen, par->nc_nlen, par->nc_name); 2625 } 2626 _cache_put(par); 2627 /* loop */ 2628 } 2629 2630 /* 2631 * Call VOP_NRESOLVE() to get the vp, then scan for any disconnected 2632 * ncp's and reattach them. If this occurs the original ncp is marked 2633 * EAGAIN to force a relookup. 2634 * 2635 * NOTE: in order to call VOP_NRESOLVE(), the parent of the passed 2636 * ncp must already be resolved. 2637 */ 2638 if (dvp) { 2639 nctmp.mount = mp; 2640 nctmp.ncp = ncp; 2641 ncp->nc_error = VOP_NRESOLVE(&nctmp, dvp, cred); 2642 vrele(dvp); 2643 } else { 2644 ncp->nc_error = EPERM; 2645 } 2646 if (ncp->nc_error == EAGAIN) { 2647 kprintf("[diagnostic] cache_resolve: EAGAIN ncp %p %*.*s\n", 2648 ncp, ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name); 2649 goto restart; 2650 } 2651 return(ncp->nc_error); 2652 } 2653 2654 /* 2655 * Resolve the ncp associated with a mount point. Such ncp's almost always 2656 * remain resolved and this routine is rarely called. NFS MPs tends to force 2657 * re-resolution more often due to its mac-truck-smash-the-namecache 2658 * method of tracking namespace changes. 2659 * 2660 * The semantics for this call is that the passed ncp must be locked on 2661 * entry and will be locked on return. However, if we actually have to 2662 * resolve the mount point we temporarily unlock the entry in order to 2663 * avoid race-to-root deadlocks due to e.g. dead NFS mounts. Because of 2664 * the unlock we have to recheck the flags after we relock. 2665 */ 2666 static int 2667 cache_resolve_mp(struct mount *mp) 2668 { 2669 struct namecache *ncp = mp->mnt_ncmountpt.ncp; 2670 struct vnode *vp; 2671 int error; 2672 2673 KKASSERT(mp != NULL); 2674 2675 /* 2676 * If the ncp is already resolved we have nothing to do. However, 2677 * we do want to guarentee that a usable vnode is returned when 2678 * a vnode is present, so make sure it hasn't been reclaimed. 2679 */ 2680 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) { 2681 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) 2682 _cache_setunresolved(ncp); 2683 } 2684 2685 if (ncp->nc_flag & NCF_UNRESOLVED) { 2686 _cache_unlock(ncp); 2687 while (vfs_busy(mp, 0)) 2688 ; 2689 error = VFS_ROOT(mp, &vp); 2690 _cache_lock(ncp); 2691 2692 /* 2693 * recheck the ncp state after relocking. 2694 */ 2695 if (ncp->nc_flag & NCF_UNRESOLVED) { 2696 ncp->nc_error = error; 2697 if (error == 0) { 2698 _cache_setvp(mp, ncp, vp); 2699 vput(vp); 2700 } else { 2701 kprintf("[diagnostic] cache_resolve_mp: failed" 2702 " to resolve mount %p err=%d ncp=%p\n", 2703 mp, error, ncp); 2704 _cache_setvp(mp, ncp, NULL); 2705 } 2706 } else if (error == 0) { 2707 vput(vp); 2708 } 2709 vfs_unbusy(mp); 2710 } 2711 return(ncp->nc_error); 2712 } 2713 2714 /* 2715 * Clean out negative cache entries when too many have accumulated. 2716 * 2717 * MPSAFE 2718 */ 2719 static void 2720 _cache_cleanneg(int count) 2721 { 2722 struct namecache *ncp; 2723 2724 /* 2725 * Automode from the vnlru proc - clean out 10% of the negative cache 2726 * entries. 2727 */ 2728 if (count == 0) 2729 count = numneg / 10 + 1; 2730 2731 /* 2732 * Attempt to clean out the specified number of negative cache 2733 * entries. 2734 */ 2735 while (count) { 2736 spin_lock_wr(&ncspin); 2737 ncp = TAILQ_FIRST(&ncneglist); 2738 if (ncp == NULL) { 2739 spin_unlock_wr(&ncspin); 2740 break; 2741 } 2742 TAILQ_REMOVE(&ncneglist, ncp, nc_vnode); 2743 TAILQ_INSERT_TAIL(&ncneglist, ncp, nc_vnode); 2744 _cache_hold(ncp); 2745 spin_unlock_wr(&ncspin); 2746 if (_cache_lock_special(ncp) == 0) { 2747 ncp = cache_zap(ncp, 0); 2748 if (ncp) 2749 _cache_drop(ncp); 2750 } else { 2751 _cache_drop(ncp); 2752 } 2753 --count; 2754 } 2755 } 2756 2757 /* 2758 * This is a kitchen sink function to clean out ncps which we 2759 * tried to zap from cache_drop() but failed because we were 2760 * unable to acquire the parent lock. 2761 * 2762 * Such entries can also be removed via cache_inval_vp(), such 2763 * as when unmounting. 2764 * 2765 * MPSAFE 2766 */ 2767 static void 2768 _cache_cleandefered(void) 2769 { 2770 struct nchash_head *nchpp; 2771 struct namecache *ncp; 2772 struct namecache dummy; 2773 int i; 2774 2775 numdefered = 0; 2776 bzero(&dummy, sizeof(dummy)); 2777 dummy.nc_flag = NCF_DESTROYED; 2778 2779 for (i = 0; i <= nchash; ++i) { 2780 nchpp = &nchashtbl[i]; 2781 2782 spin_lock_wr(&nchpp->spin); 2783 LIST_INSERT_HEAD(&nchpp->list, &dummy, nc_hash); 2784 ncp = &dummy; 2785 while ((ncp = LIST_NEXT(ncp, nc_hash)) != NULL) { 2786 if ((ncp->nc_flag & NCF_DEFEREDZAP) == 0) 2787 continue; 2788 LIST_REMOVE(&dummy, nc_hash); 2789 LIST_INSERT_AFTER(ncp, &dummy, nc_hash); 2790 _cache_hold(ncp); 2791 spin_unlock_wr(&nchpp->spin); 2792 if (_cache_lock_nonblock(ncp) == 0) { 2793 ncp->nc_flag &= ~NCF_DEFEREDZAP; 2794 _cache_unlock(ncp); 2795 } 2796 _cache_drop(ncp); 2797 spin_lock_wr(&nchpp->spin); 2798 ncp = &dummy; 2799 } 2800 LIST_REMOVE(&dummy, nc_hash); 2801 spin_unlock_wr(&nchpp->spin); 2802 } 2803 } 2804 2805 /* 2806 * Name cache initialization, from vfsinit() when we are booting 2807 */ 2808 void 2809 nchinit(void) 2810 { 2811 int i; 2812 globaldata_t gd; 2813 2814 /* initialise per-cpu namecache effectiveness statistics. */ 2815 for (i = 0; i < ncpus; ++i) { 2816 gd = globaldata_find(i); 2817 gd->gd_nchstats = &nchstats[i]; 2818 } 2819 TAILQ_INIT(&ncneglist); 2820 spin_init(&ncspin); 2821 nchashtbl = hashinit_ext(desiredvnodes*2, sizeof(struct nchash_head), 2822 M_VFSCACHE, &nchash); 2823 for (i = 0; i <= (int)nchash; ++i) { 2824 LIST_INIT(&nchashtbl[i].list); 2825 spin_init(&nchashtbl[i].spin); 2826 } 2827 nclockwarn = 5 * hz; 2828 } 2829 2830 /* 2831 * Called from start_init() to bootstrap the root filesystem. Returns 2832 * a referenced, unlocked namecache record. 2833 */ 2834 void 2835 cache_allocroot(struct nchandle *nch, struct mount *mp, struct vnode *vp) 2836 { 2837 nch->ncp = cache_alloc(0); 2838 nch->mount = mp; 2839 atomic_add_int(&mp->mnt_refs, 1); 2840 if (vp) 2841 _cache_setvp(nch->mount, nch->ncp, vp); 2842 } 2843 2844 /* 2845 * vfs_cache_setroot() 2846 * 2847 * Create an association between the root of our namecache and 2848 * the root vnode. This routine may be called several times during 2849 * booting. 2850 * 2851 * If the caller intends to save the returned namecache pointer somewhere 2852 * it must cache_hold() it. 2853 */ 2854 void 2855 vfs_cache_setroot(struct vnode *nvp, struct nchandle *nch) 2856 { 2857 struct vnode *ovp; 2858 struct nchandle onch; 2859 2860 ovp = rootvnode; 2861 onch = rootnch; 2862 rootvnode = nvp; 2863 if (nch) 2864 rootnch = *nch; 2865 else 2866 cache_zero(&rootnch); 2867 if (ovp) 2868 vrele(ovp); 2869 if (onch.ncp) 2870 cache_drop(&onch); 2871 } 2872 2873 /* 2874 * XXX OLD API COMPAT FUNCTION. This really messes up the new namecache 2875 * topology and is being removed as quickly as possible. The new VOP_N*() 2876 * API calls are required to make specific adjustments using the supplied 2877 * ncp pointers rather then just bogusly purging random vnodes. 2878 * 2879 * Invalidate all namecache entries to a particular vnode as well as 2880 * any direct children of that vnode in the namecache. This is a 2881 * 'catch all' purge used by filesystems that do not know any better. 2882 * 2883 * Note that the linkage between the vnode and its namecache entries will 2884 * be removed, but the namecache entries themselves might stay put due to 2885 * active references from elsewhere in the system or due to the existance of 2886 * the children. The namecache topology is left intact even if we do not 2887 * know what the vnode association is. Such entries will be marked 2888 * NCF_UNRESOLVED. 2889 */ 2890 void 2891 cache_purge(struct vnode *vp) 2892 { 2893 cache_inval_vp(vp, CINV_DESTROY | CINV_CHILDREN); 2894 } 2895 2896 /* 2897 * Flush all entries referencing a particular filesystem. 2898 * 2899 * Since we need to check it anyway, we will flush all the invalid 2900 * entries at the same time. 2901 */ 2902 #if 0 2903 2904 void 2905 cache_purgevfs(struct mount *mp) 2906 { 2907 struct nchash_head *nchpp; 2908 struct namecache *ncp, *nnp; 2909 2910 /* 2911 * Scan hash tables for applicable entries. 2912 */ 2913 for (nchpp = &nchashtbl[nchash]; nchpp >= nchashtbl; nchpp--) { 2914 spin_lock_wr(&nchpp->spin); XXX 2915 ncp = LIST_FIRST(&nchpp->list); 2916 if (ncp) 2917 _cache_hold(ncp); 2918 while (ncp) { 2919 nnp = LIST_NEXT(ncp, nc_hash); 2920 if (nnp) 2921 _cache_hold(nnp); 2922 if (ncp->nc_mount == mp) { 2923 _cache_lock(ncp); 2924 ncp = cache_zap(ncp, 0); 2925 if (ncp) 2926 _cache_drop(ncp); 2927 } else { 2928 _cache_drop(ncp); 2929 } 2930 ncp = nnp; 2931 } 2932 spin_unlock_wr(&nchpp->spin); XXX 2933 } 2934 } 2935 2936 #endif 2937 2938 static int disablecwd; 2939 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, ""); 2940 2941 static u_long numcwdcalls; STATNODE(CTLFLAG_RD, numcwdcalls, &numcwdcalls); 2942 static u_long numcwdfail1; STATNODE(CTLFLAG_RD, numcwdfail1, &numcwdfail1); 2943 static u_long numcwdfail2; STATNODE(CTLFLAG_RD, numcwdfail2, &numcwdfail2); 2944 static u_long numcwdfail3; STATNODE(CTLFLAG_RD, numcwdfail3, &numcwdfail3); 2945 static u_long numcwdfail4; STATNODE(CTLFLAG_RD, numcwdfail4, &numcwdfail4); 2946 static u_long numcwdfound; STATNODE(CTLFLAG_RD, numcwdfound, &numcwdfound); 2947 2948 /* 2949 * MPALMOSTSAFE 2950 */ 2951 int 2952 sys___getcwd(struct __getcwd_args *uap) 2953 { 2954 u_int buflen; 2955 int error; 2956 char *buf; 2957 char *bp; 2958 2959 if (disablecwd) 2960 return (ENODEV); 2961 2962 buflen = uap->buflen; 2963 if (buflen == 0) 2964 return (EINVAL); 2965 if (buflen > MAXPATHLEN) 2966 buflen = MAXPATHLEN; 2967 2968 buf = kmalloc(buflen, M_TEMP, M_WAITOK); 2969 get_mplock(); 2970 bp = kern_getcwd(buf, buflen, &error); 2971 rel_mplock(); 2972 if (error == 0) 2973 error = copyout(bp, uap->buf, strlen(bp) + 1); 2974 kfree(buf, M_TEMP); 2975 return (error); 2976 } 2977 2978 char * 2979 kern_getcwd(char *buf, size_t buflen, int *error) 2980 { 2981 struct proc *p = curproc; 2982 char *bp; 2983 int i, slash_prefixed; 2984 struct filedesc *fdp; 2985 struct nchandle nch; 2986 struct namecache *ncp; 2987 2988 numcwdcalls++; 2989 bp = buf; 2990 bp += buflen - 1; 2991 *bp = '\0'; 2992 fdp = p->p_fd; 2993 slash_prefixed = 0; 2994 2995 nch = fdp->fd_ncdir; 2996 ncp = nch.ncp; 2997 if (ncp) 2998 _cache_hold(ncp); 2999 3000 while (ncp && (ncp != fdp->fd_nrdir.ncp || 3001 nch.mount != fdp->fd_nrdir.mount) 3002 ) { 3003 /* 3004 * While traversing upwards if we encounter the root 3005 * of the current mount we have to skip to the mount point 3006 * in the underlying filesystem. 3007 */ 3008 if (ncp == nch.mount->mnt_ncmountpt.ncp) { 3009 nch = nch.mount->mnt_ncmounton; 3010 _cache_drop(ncp); 3011 ncp = nch.ncp; 3012 if (ncp) 3013 _cache_hold(ncp); 3014 continue; 3015 } 3016 3017 /* 3018 * Prepend the path segment 3019 */ 3020 for (i = ncp->nc_nlen - 1; i >= 0; i--) { 3021 if (bp == buf) { 3022 numcwdfail4++; 3023 *error = ERANGE; 3024 bp = NULL; 3025 goto done; 3026 } 3027 *--bp = ncp->nc_name[i]; 3028 } 3029 if (bp == buf) { 3030 numcwdfail4++; 3031 *error = ERANGE; 3032 bp = NULL; 3033 goto done; 3034 } 3035 *--bp = '/'; 3036 slash_prefixed = 1; 3037 3038 /* 3039 * Go up a directory. This isn't a mount point so we don't 3040 * have to check again. 3041 */ 3042 while ((nch.ncp = ncp->nc_parent) != NULL) { 3043 _cache_lock(ncp); 3044 if (nch.ncp != ncp->nc_parent) { 3045 _cache_unlock(ncp); 3046 continue; 3047 } 3048 _cache_hold(nch.ncp); 3049 _cache_unlock(ncp); 3050 break; 3051 } 3052 _cache_drop(ncp); 3053 ncp = nch.ncp; 3054 } 3055 if (ncp == NULL) { 3056 numcwdfail2++; 3057 *error = ENOENT; 3058 bp = NULL; 3059 goto done; 3060 } 3061 if (!slash_prefixed) { 3062 if (bp == buf) { 3063 numcwdfail4++; 3064 *error = ERANGE; 3065 bp = NULL; 3066 goto done; 3067 } 3068 *--bp = '/'; 3069 } 3070 numcwdfound++; 3071 *error = 0; 3072 done: 3073 if (ncp) 3074 _cache_drop(ncp); 3075 return (bp); 3076 } 3077 3078 /* 3079 * Thus begins the fullpath magic. 3080 * 3081 * The passed nchp is referenced but not locked. 3082 */ 3083 #undef STATNODE 3084 #define STATNODE(name) \ 3085 static u_int name; \ 3086 SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, "") 3087 3088 static int disablefullpath; 3089 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, 3090 &disablefullpath, 0, ""); 3091 3092 STATNODE(numfullpathcalls); 3093 STATNODE(numfullpathfail1); 3094 STATNODE(numfullpathfail2); 3095 STATNODE(numfullpathfail3); 3096 STATNODE(numfullpathfail4); 3097 STATNODE(numfullpathfound); 3098 3099 int 3100 cache_fullpath(struct proc *p, struct nchandle *nchp, 3101 char **retbuf, char **freebuf, int guess) 3102 { 3103 struct nchandle fd_nrdir; 3104 struct nchandle nch; 3105 struct namecache *ncp; 3106 struct mount *mp, *new_mp; 3107 char *bp, *buf; 3108 int slash_prefixed; 3109 int error = 0; 3110 int i; 3111 3112 atomic_add_int(&numfullpathcalls, -1); 3113 3114 *retbuf = NULL; 3115 *freebuf = NULL; 3116 3117 buf = kmalloc(MAXPATHLEN, M_TEMP, M_WAITOK); 3118 bp = buf + MAXPATHLEN - 1; 3119 *bp = '\0'; 3120 if (p != NULL) 3121 fd_nrdir = p->p_fd->fd_nrdir; 3122 else 3123 fd_nrdir = rootnch; 3124 slash_prefixed = 0; 3125 nch = *nchp; 3126 ncp = nch.ncp; 3127 if (ncp) 3128 _cache_hold(ncp); 3129 mp = nch.mount; 3130 3131 while (ncp && (ncp != fd_nrdir.ncp || mp != fd_nrdir.mount)) { 3132 new_mp = NULL; 3133 3134 /* 3135 * If we are asked to guess the upwards path, we do so whenever 3136 * we encounter an ncp marked as a mountpoint. We try to find 3137 * the actual mountpoint by finding the mountpoint with this ncp. 3138 */ 3139 if (guess && (ncp->nc_flag & NCF_ISMOUNTPT)) { 3140 new_mp = mount_get_by_nc(ncp); 3141 } 3142 /* 3143 * While traversing upwards if we encounter the root 3144 * of the current mount we have to skip to the mount point. 3145 */ 3146 if (ncp == mp->mnt_ncmountpt.ncp) { 3147 new_mp = mp; 3148 } 3149 if (new_mp) { 3150 nch = new_mp->mnt_ncmounton; 3151 _cache_drop(ncp); 3152 ncp = nch.ncp; 3153 if (ncp) 3154 _cache_hold(ncp); 3155 mp = nch.mount; 3156 continue; 3157 } 3158 3159 /* 3160 * Prepend the path segment 3161 */ 3162 for (i = ncp->nc_nlen - 1; i >= 0; i--) { 3163 if (bp == buf) { 3164 numfullpathfail4++; 3165 kfree(buf, M_TEMP); 3166 error = ENOMEM; 3167 goto done; 3168 } 3169 *--bp = ncp->nc_name[i]; 3170 } 3171 if (bp == buf) { 3172 numfullpathfail4++; 3173 kfree(buf, M_TEMP); 3174 error = ENOMEM; 3175 goto done; 3176 } 3177 *--bp = '/'; 3178 slash_prefixed = 1; 3179 3180 /* 3181 * Go up a directory. This isn't a mount point so we don't 3182 * have to check again. 3183 * 3184 * We can only safely access nc_parent with ncp held locked. 3185 */ 3186 while ((nch.ncp = ncp->nc_parent) != NULL) { 3187 _cache_lock(ncp); 3188 if (nch.ncp != ncp->nc_parent) { 3189 _cache_unlock(ncp); 3190 continue; 3191 } 3192 _cache_hold(nch.ncp); 3193 _cache_unlock(ncp); 3194 break; 3195 } 3196 _cache_drop(ncp); 3197 ncp = nch.ncp; 3198 } 3199 if (ncp == NULL) { 3200 numfullpathfail2++; 3201 kfree(buf, M_TEMP); 3202 error = ENOENT; 3203 goto done; 3204 } 3205 3206 if (!slash_prefixed) { 3207 if (bp == buf) { 3208 numfullpathfail4++; 3209 kfree(buf, M_TEMP); 3210 error = ENOMEM; 3211 goto done; 3212 } 3213 *--bp = '/'; 3214 } 3215 numfullpathfound++; 3216 *retbuf = bp; 3217 *freebuf = buf; 3218 error = 0; 3219 done: 3220 if (ncp) 3221 _cache_drop(ncp); 3222 return(error); 3223 } 3224 3225 int 3226 vn_fullpath(struct proc *p, struct vnode *vn, char **retbuf, char **freebuf, int guess) 3227 { 3228 struct namecache *ncp; 3229 struct nchandle nch; 3230 int error; 3231 3232 atomic_add_int(&numfullpathcalls, 1); 3233 if (disablefullpath) 3234 return (ENODEV); 3235 3236 if (p == NULL) 3237 return (EINVAL); 3238 3239 /* vn is NULL, client wants us to use p->p_textvp */ 3240 if (vn == NULL) { 3241 if ((vn = p->p_textvp) == NULL) 3242 return (EINVAL); 3243 } 3244 spin_lock_wr(&vn->v_spinlock); 3245 TAILQ_FOREACH(ncp, &vn->v_namecache, nc_vnode) { 3246 if (ncp->nc_nlen) 3247 break; 3248 } 3249 if (ncp == NULL) { 3250 spin_unlock_wr(&vn->v_spinlock); 3251 return (EINVAL); 3252 } 3253 _cache_hold(ncp); 3254 spin_unlock_wr(&vn->v_spinlock); 3255 3256 atomic_add_int(&numfullpathcalls, -1); 3257 nch.ncp = ncp;; 3258 nch.mount = vn->v_mount; 3259 error = cache_fullpath(p, &nch, retbuf, freebuf, guess); 3260 _cache_drop(ncp); 3261 return (error); 3262 } 3263