coda_namecache.c revision 1.19
1/* $NetBSD: coda_namecache.c,v 1.19 2006/10/12 01:30:47 christos Exp $ */ 2 3/* 4 * 5 * Coda: an Experimental Distributed File System 6 * Release 3.1 7 * 8 * Copyright (c) 1987-1998 Carnegie Mellon University 9 * All Rights Reserved 10 * 11 * Permission to use, copy, modify and distribute this software and its 12 * documentation is hereby granted, provided that both the copyright 13 * notice and this permission notice appear in all copies of the 14 * software, derivative works or modified versions, and any portions 15 * thereof, and that both notices appear in supporting documentation, and 16 * that credit is given to Carnegie Mellon University in all documents 17 * and publicity pertaining to direct or indirect use of this code or its 18 * derivatives. 19 * 20 * CODA IS AN EXPERIMENTAL SOFTWARE SYSTEM AND IS KNOWN TO HAVE BUGS, 21 * SOME OF WHICH MAY HAVE SERIOUS CONSEQUENCES. CARNEGIE MELLON ALLOWS 22 * FREE USE OF THIS SOFTWARE IN ITS "AS IS" CONDITION. CARNEGIE MELLON 23 * DISCLAIMS ANY LIABILITY OF ANY KIND FOR ANY DAMAGES WHATSOEVER 24 * RESULTING DIRECTLY OR INDIRECTLY FROM THE USE OF THIS SOFTWARE OR OF 25 * ANY DERIVATIVE WORK. 26 * 27 * Carnegie Mellon encourages users of this software to return any 28 * improvements or extensions that they make, and to grant Carnegie 29 * Mellon the rights to redistribute these changes without encumbrance. 30 * 31 * @(#) coda/coda_namecache.c,v 1.1.1.1 1998/08/29 21:26:45 rvb Exp $ 32 */ 33 34/* 35 * Mach Operating System 36 * Copyright (c) 1990 Carnegie-Mellon University 37 * Copyright (c) 1989 Carnegie-Mellon University 38 * All rights reserved. The CMU software License Agreement specifies 39 * the terms and conditions for use and redistribution. 40 */ 41 42/* 43 * This code was written for the Coda file system at Carnegie Mellon University. 44 * Contributers include David Steere, James Kistler, and M. Satyanarayanan. 45 */ 46 47/* 48 * This module contains the routines to implement the CODA name cache. The 49 * purpose of this cache is to reduce the cost of translating pathnames 50 * into Vice FIDs. Each entry in the cache contains the name of the file, 51 * the vnode (FID) of the parent directory, and the cred structure of the 52 * user accessing the file. 53 * 54 * The first time a file is accessed, it is looked up by the local Venus 55 * which first insures that the user has access to the file. In addition 56 * we are guaranteed that Venus will invalidate any name cache entries in 57 * case the user no longer should be able to access the file. For these 58 * reasons we do not need to keep access list information as well as a 59 * cred structure for each entry. 60 * 61 * The table can be accessed through the routines cnc_init(), cnc_enter(), 62 * cnc_lookup(), cnc_rmfidcred(), cnc_rmfid(), cnc_rmcred(), and cnc_purge(). 63 * There are several other routines which aid in the implementation of the 64 * hash table. 65 */ 66 67/* 68 * NOTES: rvb@cs 69 * 1. The name cache holds a reference to every vnode in it. Hence files can not be 70 * closed or made inactive until they are released. 71 * 2. coda_nc_name(cp) was added to get a name for a cnode pointer for debugging. 72 * 3. coda_nc_find() has debug code to detect when entries are stored with different 73 * credentials. We don't understand yet, if/how entries are NOT EQ but still 74 * EQUAL 75 * 4. I wonder if this name cache could be replace by the vnode name cache. 76 * The latter has no zapping functions, so probably not. 77 */ 78 79#include <sys/cdefs.h> 80__KERNEL_RCSID(0, "$NetBSD: coda_namecache.c,v 1.19 2006/10/12 01:30:47 christos Exp $"); 81 82#include <sys/param.h> 83#include <sys/errno.h> 84#include <sys/malloc.h> 85#include <sys/select.h> 86#include <sys/kauth.h> 87 88#include <coda/coda.h> 89#include <coda/cnode.h> 90#include <coda/coda_namecache.h> 91 92#ifdef DEBUG 93#include <coda/coda_vnops.h> 94#endif 95 96#ifndef insque 97#include <sys/systm.h> 98#endif /* insque */ 99 100/* 101 * Declaration of the name cache data structure. 102 */ 103 104int coda_nc_use = 1; /* Indicate use of CODA Name Cache */ 105 106int coda_nc_size = CODA_NC_CACHESIZE; /* size of the cache */ 107int coda_nc_hashsize = CODA_NC_HASHSIZE; /* size of the primary hash */ 108 109struct coda_cache *coda_nc_heap; /* pointer to the cache entries */ 110struct coda_hash *coda_nc_hash; /* hash table of cfscache pointers */ 111struct coda_lru coda_nc_lru; /* head of lru chain */ 112 113struct coda_nc_statistics coda_nc_stat; /* Keep various stats */ 114 115/* 116 * for testing purposes 117 */ 118int coda_nc_debug = 0; 119 120/* 121 * Entry points for the CODA Name Cache 122 */ 123static struct coda_cache * 124coda_nc_find(struct cnode *dcp, const char *name, int namelen, 125 kauth_cred_t cred, int hash); 126static void 127coda_nc_remove(struct coda_cache *cncp, enum dc_status dcstat); 128 129/* 130 * Initialize the cache, the LRU structure and the Hash structure(s) 131 */ 132 133#define TOTAL_CACHE_SIZE (sizeof(struct coda_cache) * coda_nc_size) 134#define TOTAL_HASH_SIZE (sizeof(struct coda_hash) * coda_nc_hashsize) 135 136int coda_nc_initialized = 0; /* Initially the cache has not been initialized */ 137 138void 139coda_nc_init(void) 140{ 141 int i; 142 143 /* zero the statistics structure */ 144 145 memset(&coda_nc_stat, 0, (sizeof(struct coda_nc_statistics))); 146 147#ifdef CODA_VERBOSE 148 printf("CODA NAME CACHE: CACHE %d, HASH TBL %d\n", CODA_NC_CACHESIZE, CODA_NC_HASHSIZE); 149#endif 150 CODA_ALLOC(coda_nc_heap, struct coda_cache *, TOTAL_CACHE_SIZE); 151 CODA_ALLOC(coda_nc_hash, struct coda_hash *, TOTAL_HASH_SIZE); 152 153 coda_nc_lru.lru_next = 154 coda_nc_lru.lru_prev = (struct coda_cache *)LRU_PART(&coda_nc_lru); 155 156 157 for (i=0; i < coda_nc_size; i++) { /* initialize the heap */ 158 CODA_NC_LRUINS(&coda_nc_heap[i], &coda_nc_lru); 159 CODA_NC_HSHNUL(&coda_nc_heap[i]); 160 coda_nc_heap[i].cp = coda_nc_heap[i].dcp = (struct cnode *)0; 161 } 162 163 for (i=0; i < coda_nc_hashsize; i++) { /* initialize the hashtable */ 164 CODA_NC_HSHNUL((struct coda_cache *)&coda_nc_hash[i]); 165 } 166 167 coda_nc_initialized++; 168} 169 170/* 171 * Auxillary routines -- shouldn't be entry points 172 */ 173 174static struct coda_cache * 175coda_nc_find(struct cnode *dcp, const char *name, int namelen, 176 kauth_cred_t cred, int hash) 177{ 178 /* 179 * hash to find the appropriate bucket, look through the chain 180 * for the right entry (especially right cred, unless cred == 0) 181 */ 182 struct coda_cache *cncp; 183 int count = 1; 184 185 CODA_NC_DEBUG(CODA_NC_FIND, 186 myprintf(("coda_nc_find(dcp %p, name %s, len %d, cred %p, hash %d\n", 187 dcp, name, namelen, cred, hash));) 188 189 for (cncp = coda_nc_hash[hash].hash_next; 190 cncp != (struct coda_cache *)&coda_nc_hash[hash]; 191 cncp = cncp->hash_next, count++) 192 { 193 194 if ((CODA_NAMEMATCH(cncp, name, namelen, dcp)) && 195 ((cred == 0) || (cncp->cred == cred))) 196 { 197 /* compare cr_uid instead */ 198 coda_nc_stat.Search_len += count; 199 return(cncp); 200 } 201#ifdef DEBUG 202 else if (CODA_NAMEMATCH(cncp, name, namelen, dcp)) { 203 printf("coda_nc_find: name %s, new cred = %p, cred = %p\n", 204 name, cred, cncp->cred); 205 printf("nref %d, nuid %d, ngid %d // oref %d, ocred %d, ogid %d\n", 206 kauth_cred_getrefcnt(cred), 207 kauth_cred_geteuid(cred), 208 kauth_cred_getegid(cred), 209 kauth_cred_getrefcnt(cncp->cred), 210 kauth_cred_geteuid(cncp->cred), 211 kauth_cred_getegid(cncp->cred)); 212 print_cred(cred); 213 print_cred(cncp->cred); 214 } 215#endif 216 } 217 218 return((struct coda_cache *)0); 219} 220 221/* 222 * Enter a new (dir cnode, name) pair into the cache, updating the 223 * LRU and Hash as needed. 224 */ 225void 226coda_nc_enter(struct cnode *dcp, const char *name, int namelen, 227 kauth_cred_t cred, struct cnode *cp) 228{ 229 struct coda_cache *cncp; 230 int hash; 231 232 if (coda_nc_use == 0) /* Cache is off */ 233 return; 234 235 CODA_NC_DEBUG(CODA_NC_ENTER, 236 myprintf(("Enter: dcp %p cp %p name %s cred %p \n", 237 dcp, cp, name, cred)); ) 238 239 if (namelen > CODA_NC_NAMELEN) { 240 CODA_NC_DEBUG(CODA_NC_ENTER, 241 myprintf(("long name enter %s\n",name));) 242 coda_nc_stat.long_name_enters++; /* record stats */ 243 return; 244 } 245 246 hash = CODA_NC_HASH(name, namelen, dcp); 247 cncp = coda_nc_find(dcp, name, namelen, cred, hash); 248 if (cncp != (struct coda_cache *) 0) { 249 coda_nc_stat.dbl_enters++; /* duplicate entry */ 250 return; 251 } 252 253 coda_nc_stat.enters++; /* record the enters statistic */ 254 255 /* Grab the next element in the lru chain */ 256 cncp = CODA_NC_LRUGET(coda_nc_lru); 257 258 CODA_NC_LRUREM(cncp); /* remove it from the lists */ 259 260 if (CODA_NC_VALID(cncp)) { 261 /* Seems really ugly, but we have to decrement the appropriate 262 hash bucket length here, so we have to find the hash bucket 263 */ 264 coda_nc_hash[CODA_NC_HASH(cncp->name, cncp->namelen, cncp->dcp)].length--; 265 266 coda_nc_stat.lru_rm++; /* zapped a valid entry */ 267 CODA_NC_HSHREM(cncp); 268 vrele(CTOV(cncp->dcp)); 269 vrele(CTOV(cncp->cp)); 270 kauth_cred_free(cncp->cred); 271 } 272 273 /* 274 * Put a hold on the current vnodes and fill in the cache entry. 275 */ 276 vref(CTOV(cp)); 277 vref(CTOV(dcp)); 278 kauth_cred_hold(cred); 279 cncp->dcp = dcp; 280 cncp->cp = cp; 281 cncp->namelen = namelen; 282 cncp->cred = cred; 283 284 bcopy(name, cncp->name, (unsigned)namelen); 285 286 /* Insert into the lru and hash chains. */ 287 288 CODA_NC_LRUINS(cncp, &coda_nc_lru); 289 CODA_NC_HSHINS(cncp, &coda_nc_hash[hash]); 290 coda_nc_hash[hash].length++; /* Used for tuning */ 291 292 CODA_NC_DEBUG(CODA_NC_PRINTCODA_NC, print_coda_nc(); ) 293} 294 295/* 296 * Find the (dir cnode, name) pair in the cache, if it's cred 297 * matches the input, return it, otherwise return 0 298 */ 299struct cnode * 300coda_nc_lookup(struct cnode *dcp, const char *name, int namelen, 301 kauth_cred_t cred) 302{ 303 int hash; 304 struct coda_cache *cncp; 305 306 if (coda_nc_use == 0) /* Cache is off */ 307 return((struct cnode *) 0); 308 309 if (namelen > CODA_NC_NAMELEN) { 310 CODA_NC_DEBUG(CODA_NC_LOOKUP, 311 myprintf(("long name lookup %s\n",name));) 312 coda_nc_stat.long_name_lookups++; /* record stats */ 313 return((struct cnode *) 0); 314 } 315 316 /* Use the hash function to locate the starting point, 317 then the search routine to go down the list looking for 318 the correct cred. 319 */ 320 321 hash = CODA_NC_HASH(name, namelen, dcp); 322 cncp = coda_nc_find(dcp, name, namelen, cred, hash); 323 if (cncp == (struct coda_cache *) 0) { 324 coda_nc_stat.misses++; /* record miss */ 325 return((struct cnode *) 0); 326 } 327 328 coda_nc_stat.hits++; 329 330 /* put this entry at the end of the LRU */ 331 CODA_NC_LRUREM(cncp); 332 CODA_NC_LRUINS(cncp, &coda_nc_lru); 333 334 /* move it to the front of the hash chain */ 335 /* don't need to change the hash bucket length */ 336 CODA_NC_HSHREM(cncp); 337 CODA_NC_HSHINS(cncp, &coda_nc_hash[hash]); 338 339 CODA_NC_DEBUG(CODA_NC_LOOKUP, 340 printf("lookup: dcp %p, name %s, cred %p = cp %p\n", 341 dcp, name, cred, cncp->cp); ) 342 343 return(cncp->cp); 344} 345 346static void 347coda_nc_remove(struct coda_cache *cncp, enum dc_status dcstat) 348{ 349 /* 350 * remove an entry -- vrele(cncp->dcp, cp), crfree(cred), 351 * remove it from it's hash chain, and 352 * place it at the head of the lru list. 353 */ 354 CODA_NC_DEBUG(CODA_NC_REMOVE, 355 myprintf(("coda_nc_remove %s from parent %s\n", 356 cncp->name, coda_f2s(&cncp->dcp->c_fid))); ) 357 358 359 CODA_NC_HSHREM(cncp); 360 361 CODA_NC_HSHNUL(cncp); /* have it be a null chain */ 362 if ((dcstat == IS_DOWNCALL) && (CTOV(cncp->dcp)->v_usecount == 1)) { 363 cncp->dcp->c_flags |= C_PURGING; 364 } 365 vrele(CTOV(cncp->dcp)); 366 367 if ((dcstat == IS_DOWNCALL) && (CTOV(cncp->cp)->v_usecount == 1)) { 368 cncp->cp->c_flags |= C_PURGING; 369 } 370 vrele(CTOV(cncp->cp)); 371 372 kauth_cred_free(cncp->cred); 373 memset(DATA_PART(cncp), 0, DATA_SIZE); 374 375 /* Put the null entry just after the least-recently-used entry */ 376 /* LRU_TOP adjusts the pointer to point to the top of the structure. */ 377 CODA_NC_LRUREM(cncp); 378 CODA_NC_LRUINS(cncp, LRU_TOP(coda_nc_lru.lru_prev)); 379} 380 381/* 382 * Remove all entries with a parent which has the input fid. 383 */ 384void 385coda_nc_zapParentfid(CodaFid *fid, enum dc_status dcstat) 386{ 387 /* To get to a specific fid, we might either have another hashing 388 function or do a sequential search through the cache for the 389 appropriate entries. The later may be acceptable since I don't 390 think callbacks or whatever Case 1 covers are frequent occurrences. 391 */ 392 struct coda_cache *cncp, *ncncp; 393 int i; 394 395 if (coda_nc_use == 0) /* Cache is off */ 396 return; 397 398 CODA_NC_DEBUG(CODA_NC_ZAPPFID, 399 myprintf(("ZapParent: fid %s\n", coda_f2s(fid))); ) 400 401 coda_nc_stat.zapPfids++; 402 403 for (i = 0; i < coda_nc_hashsize; i++) { 404 405 /* 406 * Need to save the hash_next pointer in case we remove the 407 * entry. remove causes hash_next to point to itself. 408 */ 409 410 for (cncp = coda_nc_hash[i].hash_next; 411 cncp != (struct coda_cache *)&coda_nc_hash[i]; 412 cncp = ncncp) { 413 ncncp = cncp->hash_next; 414 if (coda_fid_eq(&(cncp->dcp->c_fid), fid)) { 415 coda_nc_hash[i].length--; /* Used for tuning */ 416 coda_nc_remove(cncp, dcstat); 417 } 418 } 419 } 420} 421 422/* 423 * Remove all entries which have the same fid as the input 424 */ 425void 426coda_nc_zapfid(CodaFid *fid, enum dc_status dcstat) 427{ 428 /* See comment for zapParentfid. This routine will be used 429 if attributes are being cached. 430 */ 431 struct coda_cache *cncp, *ncncp; 432 int i; 433 434 if (coda_nc_use == 0) /* Cache is off */ 435 return; 436 437 CODA_NC_DEBUG(CODA_NC_ZAPFID, 438 myprintf(("Zapfid: fid %s\n", coda_f2s(fid))); ) 439 440 coda_nc_stat.zapFids++; 441 442 for (i = 0; i < coda_nc_hashsize; i++) { 443 for (cncp = coda_nc_hash[i].hash_next; 444 cncp != (struct coda_cache *)&coda_nc_hash[i]; 445 cncp = ncncp) { 446 ncncp = cncp->hash_next; 447 if (coda_fid_eq(&cncp->cp->c_fid, fid)) { 448 coda_nc_hash[i].length--; /* Used for tuning */ 449 coda_nc_remove(cncp, dcstat); 450 } 451 } 452 } 453} 454 455/* 456 * Remove all entries which match the fid and the cred 457 */ 458void 459coda_nc_zapvnode(CodaFid *fid, kauth_cred_t cred, 460 enum dc_status dcstat __unused) 461{ 462 /* See comment for zapfid. I don't think that one would ever 463 want to zap a file with a specific cred from the kernel. 464 We'll leave this one unimplemented. 465 */ 466 if (coda_nc_use == 0) /* Cache is off */ 467 return; 468 469 CODA_NC_DEBUG(CODA_NC_ZAPVNODE, 470 myprintf(("Zapvnode: fid %s cred %p\n", 471 coda_f2s(fid), cred)); ) 472} 473 474/* 475 * Remove all entries which have the (dir vnode, name) pair 476 */ 477void 478coda_nc_zapfile(struct cnode *dcp, const char *name, int namelen) 479{ 480 /* use the hash function to locate the file, then zap all 481 entries of it regardless of the cred. 482 */ 483 struct coda_cache *cncp; 484 int hash; 485 486 if (coda_nc_use == 0) /* Cache is off */ 487 return; 488 489 CODA_NC_DEBUG(CODA_NC_ZAPFILE, 490 myprintf(("Zapfile: dcp %p name %s \n", 491 dcp, name)); ) 492 493 if (namelen > CODA_NC_NAMELEN) { 494 coda_nc_stat.long_remove++; /* record stats */ 495 return; 496 } 497 498 coda_nc_stat.zapFile++; 499 500 hash = CODA_NC_HASH(name, namelen, dcp); 501 cncp = coda_nc_find(dcp, name, namelen, 0, hash); 502 503 while (cncp) { 504 coda_nc_hash[hash].length--; /* Used for tuning */ 505/* 1.3 */ 506 coda_nc_remove(cncp, NOT_DOWNCALL); 507 cncp = coda_nc_find(dcp, name, namelen, 0, hash); 508 } 509} 510 511/* 512 * Remove all the entries for a particular user. Used when tokens expire. 513 * A user is determined by his/her effective user id (id_uid). 514 */ 515void 516coda_nc_purge_user(uid_t uid, enum dc_status dcstat) 517{ 518 /* 519 * I think the best approach is to go through the entire cache 520 * via HASH or whatever and zap all entries which match the 521 * input cred. Or just flush the whole cache. It might be 522 * best to go through on basis of LRU since cache will almost 523 * always be full and LRU is more straightforward. 524 */ 525 526 struct coda_cache *cncp, *ncncp; 527 int hash; 528 529 if (coda_nc_use == 0) /* Cache is off */ 530 return; 531 532 CODA_NC_DEBUG(CODA_NC_PURGEUSER, 533 myprintf(("ZapDude: uid %x\n", uid)); ) 534 coda_nc_stat.zapUsers++; 535 536 for (cncp = CODA_NC_LRUGET(coda_nc_lru); 537 cncp != (struct coda_cache *)(&coda_nc_lru); 538 cncp = ncncp) { 539 ncncp = CODA_NC_LRUGET(*cncp); 540 541 if ((CODA_NC_VALID(cncp)) && 542 (kauth_cred_geteuid(cncp->cred) == uid)) { 543 /* Seems really ugly, but we have to decrement the appropriate 544 hash bucket length here, so we have to find the hash bucket 545 */ 546 hash = CODA_NC_HASH(cncp->name, cncp->namelen, cncp->dcp); 547 coda_nc_hash[hash].length--; /* For performance tuning */ 548 549 coda_nc_remove(cncp, dcstat); 550 } 551 } 552} 553 554/* 555 * Flush the entire name cache. In response to a flush of the Venus cache. 556 */ 557void 558coda_nc_flush(enum dc_status dcstat) 559{ 560 /* One option is to deallocate the current name cache and 561 call init to start again. Or just deallocate, then rebuild. 562 Or again, we could just go through the array and zero the 563 appropriate fields. 564 */ 565 566 /* 567 * Go through the whole lru chain and kill everything as we go. 568 * I don't use remove since that would rebuild the lru chain 569 * as it went and that seemed unneccesary. 570 */ 571 struct coda_cache *cncp; 572 int i; 573 574 if (coda_nc_use == 0) /* Cache is off */ 575 return; 576 577 coda_nc_stat.Flushes++; 578 579 for (cncp = CODA_NC_LRUGET(coda_nc_lru); 580 cncp != (struct coda_cache *)&coda_nc_lru; 581 cncp = CODA_NC_LRUGET(*cncp)) { 582 if (CODA_NC_VALID(cncp)) { 583 584 CODA_NC_HSHREM(cncp); /* only zero valid nodes */ 585 CODA_NC_HSHNUL(cncp); 586 if ((dcstat == IS_DOWNCALL) 587 && (CTOV(cncp->dcp)->v_usecount == 1)) 588 { 589 cncp->dcp->c_flags |= C_PURGING; 590 } 591 vrele(CTOV(cncp->dcp)); 592 593 if (CTOV(cncp->cp)->v_flag & VTEXT) { 594 if (coda_vmflush(cncp->cp)) 595 CODADEBUG(CODA_FLUSH, 596 myprintf(("coda_nc_flush: %s busy\n", 597 coda_f2s(&cncp->cp->c_fid))); ) 598 } 599 600 if ((dcstat == IS_DOWNCALL) 601 && (CTOV(cncp->cp)->v_usecount == 1)) 602 { 603 cncp->cp->c_flags |= C_PURGING; 604 } 605 vrele(CTOV(cncp->cp)); 606 607 kauth_cred_free(cncp->cred); 608 memset(DATA_PART(cncp), 0, DATA_SIZE); 609 } 610 } 611 612 for (i = 0; i < coda_nc_hashsize; i++) 613 coda_nc_hash[i].length = 0; 614} 615 616/* 617 * Debugging routines 618 */ 619 620/* 621 * This routine should print out all the hash chains to the console. 622 */ 623void 624print_coda_nc(void) 625{ 626 int hash; 627 struct coda_cache *cncp; 628 629 for (hash = 0; hash < coda_nc_hashsize; hash++) { 630 myprintf(("\nhash %d\n",hash)); 631 632 for (cncp = coda_nc_hash[hash].hash_next; 633 cncp != (struct coda_cache *)&coda_nc_hash[hash]; 634 cncp = cncp->hash_next) { 635 myprintf(("cp %p dcp %p cred %p name %s\n", 636 cncp->cp, cncp->dcp, 637 cncp->cred, cncp->name)); 638 } 639 } 640} 641 642void 643coda_nc_gather_stats(void) 644{ 645 int i, xmax = 0, sum = 0, temp, zeros = 0, ave, n; 646 647 for (i = 0; i < coda_nc_hashsize; i++) { 648 if (coda_nc_hash[i].length) { 649 sum += coda_nc_hash[i].length; 650 } else { 651 zeros++; 652 } 653 654 if (coda_nc_hash[i].length > xmax) 655 xmax = coda_nc_hash[i].length; 656 } 657 658 /* 659 * When computing the Arithmetic mean, only count slots which 660 * are not empty in the distribution. 661 */ 662 coda_nc_stat.Sum_bucket_len = sum; 663 coda_nc_stat.Num_zero_len = zeros; 664 coda_nc_stat.Max_bucket_len = xmax; 665 666 if ((n = coda_nc_hashsize - zeros) > 0) 667 ave = sum / n; 668 else 669 ave = 0; 670 671 sum = 0; 672 for (i = 0; i < coda_nc_hashsize; i++) { 673 if (coda_nc_hash[i].length) { 674 temp = coda_nc_hash[i].length - ave; 675 sum += temp * temp; 676 } 677 } 678 coda_nc_stat.Sum2_bucket_len = sum; 679} 680 681/* 682 * The purpose of this routine is to allow the hash and cache sizes to be 683 * changed dynamically. This should only be used in controlled environments, 684 * it makes no effort to lock other users from accessing the cache while it 685 * is in an improper state (except by turning the cache off). 686 */ 687int 688coda_nc_resize(int hashsize, int heapsize, enum dc_status dcstat) 689{ 690 if ((hashsize % 2) || (heapsize % 2)) { /* Illegal hash or cache sizes */ 691 return(EINVAL); 692 } 693 694 coda_nc_use = 0; /* Turn the cache off */ 695 696 coda_nc_flush(dcstat); /* free any cnodes in the cache */ 697 698 /* WARNING: free must happen *before* size is reset */ 699 CODA_FREE(coda_nc_heap,TOTAL_CACHE_SIZE); 700 CODA_FREE(coda_nc_hash,TOTAL_HASH_SIZE); 701 702 coda_nc_hashsize = hashsize; 703 coda_nc_size = heapsize; 704 705 coda_nc_init(); /* Set up a cache with the new size */ 706 707 coda_nc_use = 1; /* Turn the cache back on */ 708 return(0); 709} 710 711char coda_nc_name_buf[CODA_MAXNAMLEN+1]; 712 713void 714coda_nc_name(struct cnode *cp) 715{ 716 struct coda_cache *cncp, *ncncp; 717 int i; 718 719 if (coda_nc_use == 0) /* Cache is off */ 720 return; 721 722 for (i = 0; i < coda_nc_hashsize; i++) { 723 for (cncp = coda_nc_hash[i].hash_next; 724 cncp != (struct coda_cache *)&coda_nc_hash[i]; 725 cncp = ncncp) { 726 ncncp = cncp->hash_next; 727 if (cncp->cp == cp) { 728 bcopy(cncp->name, coda_nc_name_buf, cncp->namelen); 729 coda_nc_name_buf[cncp->namelen] = 0; 730 printf(" is %s (%p,%p)@%p", 731 coda_nc_name_buf, cncp->cp, cncp->dcp, cncp); 732 } 733 734 } 735 } 736} 737