1/*	$NetBSD: coda_namecache.c,v 1.30 2024/05/17 23:57:46 thorpej 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 1.30 2024/05/17 23:57:46 thorpej Exp $");
81
82#include <sys/param.h>
83#include <sys/errno.h>
84#include <sys/select.h>
85#include <sys/kauth.h>
86
87#include <coda/coda.h>
88#include <coda/cnode.h>
89#include <coda/coda_namecache.h>
90#include <coda/coda_subr.h>
91
92/*
93 * Declaration of the name cache data structure.
94 */
95
96int 	coda_nc_use = 1;			 /* Indicate use of CODA Name Cache */
97
98int	coda_nc_size = CODA_NC_CACHESIZE;	 /* size of the cache */
99int	coda_nc_hashsize = CODA_NC_HASHSIZE; /* size of the primary hash */
100
101struct 	coda_cache *coda_nc_heap;	/* pointer to the cache entries */
102struct	coda_hash  *coda_nc_hash;	/* hash table of cfscache pointers */
103struct	coda_lru   coda_nc_lru;		/* head of lru chain */
104
105struct coda_nc_statistics coda_nc_stat;	/* Keep various stats */
106
107/*
108 * for testing purposes
109 */
110int coda_nc_debug = 0;
111
112/*
113 * Entry points for the CODA Name Cache
114 */
115static struct coda_cache *
116coda_nc_find(struct cnode *dcp, const char *name, int namelen,
117	kauth_cred_t cred, int hash);
118static void
119coda_nc_remove(struct coda_cache *cncp, enum dc_status dcstat);
120
121/*
122 * Initialize the cache, the LRU structure and the Hash structure(s)
123 */
124
125#define TOTAL_CACHE_SIZE 	(sizeof(struct coda_cache) * coda_nc_size)
126#define TOTAL_HASH_SIZE 	(sizeof(struct coda_hash)  * coda_nc_hashsize)
127
128int coda_nc_initialized = 0;      /* Initially the cache has not been initialized */
129
130void
131coda_nc_init(void)
132{
133    int i;
134
135    /* zero the statistics structure */
136
137    memset(&coda_nc_stat, 0, (sizeof(struct coda_nc_statistics)));
138
139#ifdef	CODA_VERBOSE
140    printf("CODA NAME CACHE: CACHE %d, HASH TBL %d\n", CODA_NC_CACHESIZE, CODA_NC_HASHSIZE);
141#endif
142    CODA_ALLOC(coda_nc_heap, struct coda_cache *, TOTAL_CACHE_SIZE);
143    CODA_ALLOC(coda_nc_hash, struct coda_hash *, TOTAL_HASH_SIZE);
144
145    memset(coda_nc_heap, 0, TOTAL_CACHE_SIZE);
146    memset(coda_nc_hash, 0, TOTAL_HASH_SIZE);
147
148    TAILQ_INIT(&coda_nc_lru.head);
149
150    for (i=0; i < coda_nc_size; i++) {	/* initialize the heap */
151	TAILQ_INSERT_HEAD(&coda_nc_lru.head, &coda_nc_heap[i], lru);
152    }
153
154    for (i=0; i < coda_nc_hashsize; i++) {	/* initialize the hashtable */
155	LIST_INIT(&coda_nc_hash[i].head);
156    }
157
158    coda_nc_initialized++;
159}
160
161/*
162 * Auxiliary routines -- shouldn't be entry points
163 */
164
165static struct coda_cache *
166coda_nc_find(struct cnode *dcp, const char *name, int namelen,
167	kauth_cred_t cred, int hash)
168{
169	/*
170	 * hash to find the appropriate bucket, look through the chain
171	 * for the right entry (especially right cred, unless cred == 0)
172	 */
173	struct coda_cache *cncp;
174	int count = 1;
175
176	CODA_NC_DEBUG(CODA_NC_FIND,
177		myprintf(("coda_nc_find(dcp %p, name %s, len %d, cred %p, hash %d\n",
178			dcp, name, namelen, cred, hash));)
179
180	LIST_FOREACH(cncp, &coda_nc_hash[hash].head, hash)
181	{
182
183	    if ((CODA_NAMEMATCH(cncp, name, namelen, dcp)) &&
184		((cred == 0) || (cncp->cred == cred)))
185	    {
186		/* compare cr_uid instead */
187		coda_nc_stat.Search_len += count;
188		return(cncp);
189	    }
190#ifdef	DEBUG
191	    else if (CODA_NAMEMATCH(cncp, name, namelen, dcp)) {
192	    	printf("coda_nc_find: name %s, new cred = %p, cred = %p\n",
193			name, cred, cncp->cred);
194		printf("nref %d, nuid %d, ngid %d // oref %d, ocred %d, ogid %d\n",
195			kauth_cred_getrefcnt(cred),
196			kauth_cred_geteuid(cred),
197			kauth_cred_getegid(cred),
198			kauth_cred_getrefcnt(cncp->cred),
199			kauth_cred_geteuid(cncp->cred),
200			kauth_cred_getegid(cncp->cred));
201		coda_print_cred(cred);
202		coda_print_cred(cncp->cred);
203	    }
204#endif
205	    count++;
206	}
207
208	return((struct coda_cache *)0);
209}
210
211/*
212 * Enter a new (dir cnode, name) pair into the cache, updating the
213 * LRU and Hash as needed.
214 */
215void
216coda_nc_enter(struct cnode *dcp, const char *name, int namelen,
217	kauth_cred_t cred, struct cnode *cp)
218{
219    struct coda_cache *cncp;
220    int hash;
221
222    if (coda_nc_use == 0)			/* Cache is off */
223	return;
224
225    CODA_NC_DEBUG(CODA_NC_ENTER,
226		myprintf(("Enter: dcp %p cp %p name %s cred %p \n",
227		       dcp, cp, name, cred)); )
228
229    if (namelen > CODA_NC_NAMELEN) {
230	CODA_NC_DEBUG(CODA_NC_ENTER,
231		    myprintf(("long name enter %s\n",name));)
232	    coda_nc_stat.long_name_enters++;	/* record stats */
233	return;
234    }
235
236    hash = CODA_NC_HASH(name, namelen, dcp);
237    cncp = coda_nc_find(dcp, name, namelen, cred, hash);
238    if (cncp != (struct coda_cache *) 0) {
239	coda_nc_stat.dbl_enters++;		/* duplicate entry */
240	return;
241    }
242
243    coda_nc_stat.enters++;		/* record the enters statistic */
244
245    /* Grab the next element in the lru chain */
246    cncp = TAILQ_FIRST(&coda_nc_lru.head);
247    TAILQ_REMOVE(&coda_nc_lru.head, cncp, lru);
248
249    if (CODA_NC_VALID(cncp)) {
250	/* Seems really ugly, but we have to decrement the appropriate
251	   hash bucket length here, so we have to find the hash bucket
252	   */
253	coda_nc_hash[CODA_NC_HASH(cncp->name, cncp->namelen, cncp->dcp)].length--;
254
255	coda_nc_stat.lru_rm++;	/* zapped a valid entry */
256	LIST_REMOVE(cncp, hash);
257	vrele(CTOV(cncp->dcp));
258	vrele(CTOV(cncp->cp));
259	kauth_cred_free(cncp->cred);
260    }
261
262    /*
263     * Put a hold on the current vnodes and fill in the cache entry.
264     */
265    vref(CTOV(cp));
266    vref(CTOV(dcp));
267    kauth_cred_hold(cred);
268    cncp->dcp = dcp;
269    cncp->cp = cp;
270    cncp->namelen = namelen;
271    cncp->cred = cred;
272
273    memcpy(cncp->name, name, (unsigned)namelen);
274
275    /* Insert into the lru and hash chains. */
276    TAILQ_INSERT_TAIL(&coda_nc_lru.head, cncp, lru);
277    LIST_INSERT_HEAD(&coda_nc_hash[hash].head, cncp, hash);
278    coda_nc_hash[hash].length++;                      /* Used for tuning */
279
280    CODA_NC_DEBUG(CODA_NC_PRINTCODA_NC, print_coda_nc(); )
281}
282
283/*
284 * Find the (dir cnode, name) pair in the cache, if its cred
285 * matches the input, return it, otherwise return 0
286 */
287struct cnode *
288coda_nc_lookup(struct cnode *dcp, const char *name, int namelen,
289	kauth_cred_t cred)
290{
291	int hash;
292	struct coda_cache *cncp;
293
294	if (coda_nc_use == 0)			/* Cache is off */
295		return((struct cnode *) 0);
296
297	if (namelen > CODA_NC_NAMELEN) {
298	        CODA_NC_DEBUG(CODA_NC_LOOKUP,
299			    myprintf(("long name lookup %s\n",name));)
300		coda_nc_stat.long_name_lookups++;		/* record stats */
301		return((struct cnode *) 0);
302	}
303
304	/* Use the hash function to locate the starting point,
305	   then the search routine to go down the list looking for
306	   the correct cred.
307 	 */
308
309	hash = CODA_NC_HASH(name, namelen, dcp);
310	cncp = coda_nc_find(dcp, name, namelen, cred, hash);
311	if (cncp == (struct coda_cache *) 0) {
312		coda_nc_stat.misses++;			/* record miss */
313		return((struct cnode *) 0);
314	}
315
316	coda_nc_stat.hits++;
317
318	/* put this entry at the end of the LRU */
319	TAILQ_REMOVE(&coda_nc_lru.head, cncp, lru);
320	TAILQ_INSERT_TAIL(&coda_nc_lru.head, cncp, lru);
321
322	/* move it to the front of the hash chain */
323	/* don't need to change the hash bucket length */
324	LIST_REMOVE(cncp, hash);
325	LIST_INSERT_HEAD(&coda_nc_hash[hash].head, cncp, hash);
326
327	CODA_NC_DEBUG(CODA_NC_LOOKUP,
328		printf("lookup: dcp %p, name %s, cred %p = cp %p\n",
329			dcp, name, cred, cncp->cp); )
330
331	return(cncp->cp);
332}
333
334static void
335coda_nc_remove(struct coda_cache *cncp, enum dc_status dcstat)
336{
337	/*
338	 * remove an entry -- vrele(cncp->dcp, cp), crfree(cred),
339	 * remove it from its hash chain, and
340	 * place it at the head of the lru list.
341	 */
342        CODA_NC_DEBUG(CODA_NC_REMOVE,
343		    myprintf(("coda_nc_remove %s from parent %s\n",
344			      cncp->name, coda_f2s(&cncp->dcp->c_fid))); )
345
346
347	LIST_REMOVE(cncp, hash);
348	memset(&cncp->hash, 0, sizeof(cncp->hash));
349
350	if ((dcstat == IS_DOWNCALL) && (vrefcnt(CTOV(cncp->dcp)) == 1)) {
351		cncp->dcp->c_flags |= C_PURGING;
352	}
353	vrele(CTOV(cncp->dcp));
354
355	if ((dcstat == IS_DOWNCALL) && (vrefcnt(CTOV(cncp->cp)) == 1)) {
356		cncp->cp->c_flags |= C_PURGING;
357	}
358	vrele(CTOV(cncp->cp));
359
360	kauth_cred_free(cncp->cred);
361	memset(DATA_PART(cncp), 0, DATA_SIZE);
362
363	/* move the null entry to the front for reuse */
364	TAILQ_REMOVE(&coda_nc_lru.head, cncp, lru);
365	TAILQ_INSERT_HEAD(&coda_nc_lru.head, cncp, lru);
366}
367
368/*
369 * Remove all entries with a parent which has the input fid.
370 */
371void
372coda_nc_zapParentfid(CodaFid *fid, enum dc_status dcstat)
373{
374	/* To get to a specific fid, we might either have another hashing
375	   function or do a sequential search through the cache for the
376	   appropriate entries. The later may be acceptable since I don't
377	   think callbacks or whatever Case 1 covers are frequent occurrences.
378	 */
379	struct coda_cache *cncp, *ncncp;
380	int i;
381
382	if (coda_nc_use == 0)			/* Cache is off */
383		return;
384
385	CODA_NC_DEBUG(CODA_NC_ZAPPFID,
386		myprintf(("ZapParent: fid %s\n", coda_f2s(fid))); )
387
388	coda_nc_stat.zapPfids++;
389
390	for (i = 0; i < coda_nc_hashsize; i++) {
391
392		/*
393		 * Need to save the hash_next pointer in case we remove the
394		 * entry. remove causes hash_next to point to itself.
395		 */
396
397		ncncp = LIST_FIRST(&coda_nc_hash[i].head);
398		while ((cncp = ncncp) != NULL) {
399			ncncp = LIST_NEXT(cncp, hash);
400
401			if (coda_fid_eq(&(cncp->dcp->c_fid), fid)) {
402			        coda_nc_hash[i].length--;      /* Used for tuning */
403				coda_nc_remove(cncp, dcstat);
404			}
405		}
406	}
407}
408
409/*
410 * Remove all entries which have the same fid as the input
411 */
412void
413coda_nc_zapfid(CodaFid *fid, enum dc_status dcstat)
414{
415	/* See comment for zapParentfid. This routine will be used
416	   if attributes are being cached.
417	 */
418	struct coda_cache *cncp, *ncncp;
419	int i;
420
421	if (coda_nc_use == 0)			/* Cache is off */
422		return;
423
424	CODA_NC_DEBUG(CODA_NC_ZAPFID,
425		myprintf(("Zapfid: fid %s\n", coda_f2s(fid))); )
426
427	coda_nc_stat.zapFids++;
428
429	for (i = 0; i < coda_nc_hashsize; i++) {
430
431		ncncp = LIST_FIRST(&coda_nc_hash[i].head);
432		while ((cncp = ncncp) != NULL) {
433			ncncp = LIST_NEXT(cncp, hash);
434
435			if (coda_fid_eq(&cncp->cp->c_fid, fid)) {
436			        coda_nc_hash[i].length--;     /* Used for tuning */
437				coda_nc_remove(cncp, dcstat);
438			}
439		}
440	}
441}
442
443/*
444 * Remove all entries which match the fid and the cred
445 */
446void
447coda_nc_zapvnode(CodaFid *fid, kauth_cred_t cred,
448    enum dc_status dcstat)
449{
450	/* See comment for zapfid. I don't think that one would ever
451	   want to zap a file with a specific cred from the kernel.
452	   We'll leave this one unimplemented.
453	 */
454	if (coda_nc_use == 0)			/* Cache is off */
455		return;
456
457	CODA_NC_DEBUG(CODA_NC_ZAPVNODE,
458		myprintf(("Zapvnode: fid %s cred %p\n",
459			  coda_f2s(fid), cred)); )
460}
461
462/*
463 * Remove all entries which have the (dir vnode, name) pair
464 */
465void
466coda_nc_zapfile(struct cnode *dcp, const char *name, int namelen)
467{
468	/* use the hash function to locate the file, then zap all
469 	   entries of it regardless of the cred.
470	 */
471	struct coda_cache *cncp;
472	int hash;
473
474	if (coda_nc_use == 0)			/* Cache is off */
475		return;
476
477	CODA_NC_DEBUG(CODA_NC_ZAPFILE,
478		myprintf(("Zapfile: dcp %p name %s \n",
479			  dcp, name)); )
480
481	if (namelen > CODA_NC_NAMELEN) {
482		coda_nc_stat.long_remove++;		/* record stats */
483		return;
484	}
485
486	coda_nc_stat.zapFile++;
487
488	hash = CODA_NC_HASH(name, namelen, dcp);
489	cncp = coda_nc_find(dcp, name, namelen, 0, hash);
490
491	while (cncp) {
492	  coda_nc_hash[hash].length--;                 /* Used for tuning */
493/* 1.3 */
494	  coda_nc_remove(cncp, NOT_DOWNCALL);
495	  cncp = coda_nc_find(dcp, name, namelen, 0, hash);
496	}
497}
498
499/*
500 * Remove all the entries for a particular user. Used when tokens expire.
501 * A user is determined by his/her effective user id (id_uid).
502 */
503void
504coda_nc_purge_user(uid_t uid, enum dc_status dcstat)
505{
506	/*
507	 * I think the best approach is to go through the entire cache
508	 * via HASH or whatever and zap all entries which match the
509	 * input cred. Or just flush the whole cache.  It might be
510	 * best to go through on basis of LRU since cache will almost
511	 * always be full and LRU is more straightforward.
512	 */
513
514	struct coda_cache *cncp, *ncncp;
515	int hash;
516
517	if (coda_nc_use == 0)			/* Cache is off */
518		return;
519
520	CODA_NC_DEBUG(CODA_NC_PURGEUSER,
521		myprintf(("ZapDude: uid %x\n", uid)); )
522	coda_nc_stat.zapUsers++;
523
524	ncncp = TAILQ_FIRST(&coda_nc_lru.head);
525	while ((cncp = ncncp) != NULL) {
526		ncncp = TAILQ_NEXT(cncp, lru);
527
528		if ((CODA_NC_VALID(cncp)) &&
529		   (kauth_cred_geteuid(cncp->cred) == uid)) {
530		        /* Seems really ugly, but we have to decrement the appropriate
531			   hash bucket length here, so we have to find the hash bucket
532			   */
533		        hash = CODA_NC_HASH(cncp->name, cncp->namelen, cncp->dcp);
534			coda_nc_hash[hash].length--;     /* For performance tuning */
535
536			coda_nc_remove(cncp, dcstat);
537		}
538	}
539}
540
541/*
542 * Flush the entire name cache. In response to a flush of the Venus cache.
543 */
544void
545coda_nc_flush(enum dc_status dcstat)
546{
547	/* One option is to deallocate the current name cache and
548	   call init to start again. Or just deallocate, then rebuild.
549	   Or again, we could just go through the array and zero the
550	   appropriate fields.
551	 */
552
553	/*
554	 * Go through the whole lru chain and kill everything as we go.
555	 * I don't use remove since that would rebuild the lru chain
556	 * as it went and that seemed unnecessary.
557	 */
558	struct coda_cache *cncp;
559	int i;
560
561	if (coda_nc_use == 0)			/* Cache is off */
562		return;
563
564	coda_nc_stat.Flushes++;
565
566	TAILQ_FOREACH(cncp, &coda_nc_lru.head, lru) {
567		if (CODA_NC_VALID(cncp)) {	/* only zero valid nodes */
568			LIST_REMOVE(cncp, hash);
569			memset(&cncp->hash, 0, sizeof(cncp->hash));
570
571			if ((dcstat == IS_DOWNCALL)
572			    && (vrefcnt(CTOV(cncp->dcp)) == 1))
573			{
574				cncp->dcp->c_flags |= C_PURGING;
575			}
576			vrele(CTOV(cncp->dcp));
577
578			if (CTOV(cncp->cp)->v_iflag & VI_TEXT) {
579			    if (coda_vmflush(cncp->cp))
580				CODADEBUG(CODA_FLUSH,
581					myprintf(("coda_nc_flush: %s busy\n",
582						coda_f2s(&cncp->cp->c_fid))); )
583			}
584
585			if ((dcstat == IS_DOWNCALL)
586			    && (vrefcnt(CTOV(cncp->cp)) == 1))
587			{
588				cncp->cp->c_flags |= C_PURGING;
589			}
590			vrele(CTOV(cncp->cp));
591
592			kauth_cred_free(cncp->cred);
593			memset(DATA_PART(cncp), 0, DATA_SIZE);
594		}
595	}
596
597	for (i = 0; i < coda_nc_hashsize; i++)
598	  coda_nc_hash[i].length = 0;
599}
600
601/*
602 * Debugging routines
603 */
604
605/*
606 * This routine should print out all the hash chains to the console.
607 */
608void
609print_coda_nc(void)
610{
611	int hash;
612	struct coda_cache *cncp;
613
614	for (hash = 0; hash < coda_nc_hashsize; hash++) {
615		myprintf(("\nhash %d\n",hash));
616
617		LIST_FOREACH(cncp, &coda_nc_hash[hash].head, hash) {
618			myprintf(("cp %p dcp %p cred %p name %s\n",
619				  cncp->cp, cncp->dcp,
620				  cncp->cred, cncp->name));
621		     }
622	}
623}
624
625void
626coda_nc_gather_stats(void)
627{
628    int i, xmax = 0, sum = 0, temp, zeros = 0, ave, n;
629
630	for (i = 0; i < coda_nc_hashsize; i++) {
631	  if (coda_nc_hash[i].length) {
632	    sum += coda_nc_hash[i].length;
633	  } else {
634	    zeros++;
635	  }
636
637	  if (coda_nc_hash[i].length > xmax)
638	    xmax = coda_nc_hash[i].length;
639	}
640
641	/*
642	 * When computing the Arithmetic mean, only count slots which
643	 * are not empty in the distribution.
644	 */
645        coda_nc_stat.Sum_bucket_len = sum;
646        coda_nc_stat.Num_zero_len = zeros;
647        coda_nc_stat.Max_bucket_len = xmax;
648
649	if ((n = coda_nc_hashsize - zeros) > 0)
650	  ave = sum / n;
651	else
652	  ave = 0;
653
654	sum = 0;
655	for (i = 0; i < coda_nc_hashsize; i++) {
656	  if (coda_nc_hash[i].length) {
657	    temp = coda_nc_hash[i].length - ave;
658	    sum += temp * temp;
659	  }
660	}
661        coda_nc_stat.Sum2_bucket_len = sum;
662}
663
664/*
665 * The purpose of this routine is to allow the hash and cache sizes to be
666 * changed dynamically. This should only be used in controlled environments,
667 * it makes no effort to lock other users from accessing the cache while it
668 * is in an improper state (except by turning the cache off).
669 */
670int
671coda_nc_resize(int hashsize, int heapsize, enum dc_status dcstat)
672{
673    if ((hashsize % 2) || (heapsize % 2)) { /* Illegal hash or cache sizes */
674	return(EINVAL);
675    }
676
677    coda_nc_use = 0;                       /* Turn the cache off */
678
679    coda_nc_flush(dcstat);                 /* free any cnodes in the cache */
680
681    /* WARNING: free must happen *before* size is reset */
682    CODA_FREE(coda_nc_heap,TOTAL_CACHE_SIZE);
683    CODA_FREE(coda_nc_hash,TOTAL_HASH_SIZE);
684
685    coda_nc_hashsize = hashsize;
686    coda_nc_size = heapsize;
687
688    coda_nc_init();                        /* Set up a cache with the new size */
689
690    coda_nc_use = 1;                       /* Turn the cache back on */
691    return(0);
692}
693
694char coda_nc_name_buf[CODA_MAXNAMLEN+1];
695
696void
697coda_nc_name(struct cnode *cp)
698{
699	struct coda_cache *cncp;
700	int i;
701
702	if (coda_nc_use == 0)			/* Cache is off */
703		return;
704
705	for (i = 0; i < coda_nc_hashsize; i++) {
706
707		LIST_FOREACH(cncp, &coda_nc_hash[i].head, hash) {
708			if (cncp->cp == cp) {
709				memcpy(coda_nc_name_buf, cncp->name, cncp->namelen);
710				coda_nc_name_buf[cncp->namelen] = 0;
711				printf(" is %s (%p,%p)@%p",
712					coda_nc_name_buf, cncp->cp, cncp->dcp, cncp);
713			}
714
715		}
716	}
717}
718