1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Request reply cache. This is currently a global cache, but this may
4 * change in the future and be a per-client cache.
5 *
6 * This code is heavily inspired by the 44BSD implementation, although
7 * it does things a bit differently.
8 *
9 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
10 */
11
12 #include <linux/sunrpc/svc_xprt.h>
13 #include <linux/slab.h>
14 #include <linux/vmalloc.h>
15 #include <linux/sunrpc/addr.h>
16 #include <linux/highmem.h>
17 #include <linux/log2.h>
18 #include <linux/hash.h>
19 #include <net/checksum.h>
20
21 #include "nfsd.h"
22 #include "cache.h"
23 #include "trace.h"
24
25 /*
26 * We use this value to determine the number of hash buckets from the max
27 * cache size, the idea being that when the cache is at its maximum number
28 * of entries, then this should be the average number of entries per bucket.
29 */
30 #define TARGET_BUCKET_SIZE 64
31
32 struct nfsd_drc_bucket {
33 struct rb_root rb_head;
34 struct list_head lru_head;
35 spinlock_t cache_lock;
36 };
37
38 static struct kmem_cache *drc_slab;
39
40 static int nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *vec);
41 static unsigned long nfsd_reply_cache_count(struct shrinker *shrink,
42 struct shrink_control *sc);
43 static unsigned long nfsd_reply_cache_scan(struct shrinker *shrink,
44 struct shrink_control *sc);
45
46 /*
47 * Put a cap on the size of the DRC based on the amount of available
48 * low memory in the machine.
49 *
50 * 64MB: 8192
51 * 128MB: 11585
52 * 256MB: 16384
53 * 512MB: 23170
54 * 1GB: 32768
55 * 2GB: 46340
56 * 4GB: 65536
57 * 8GB: 92681
58 * 16GB: 131072
59 *
60 * ...with a hard cap of 256k entries. In the worst case, each entry will be
61 * ~1k, so the above numbers should give a rough max of the amount of memory
62 * used in k.
63 *
64 * XXX: these limits are per-container, so memory used will increase
65 * linearly with number of containers. Maybe that's OK.
66 */
67 static unsigned int
nfsd_cache_size_limit(void)68 nfsd_cache_size_limit(void)
69 {
70 unsigned int limit;
71 unsigned long low_pages = totalram_pages() - totalhigh_pages();
72
73 limit = (16 * int_sqrt(low_pages)) << (PAGE_SHIFT-10);
74 return min_t(unsigned int, limit, 256*1024);
75 }
76
77 /*
78 * Compute the number of hash buckets we need. Divide the max cachesize by
79 * the "target" max bucket size, and round up to next power of two.
80 */
81 static unsigned int
nfsd_hashsize(unsigned int limit)82 nfsd_hashsize(unsigned int limit)
83 {
84 return roundup_pow_of_two(limit / TARGET_BUCKET_SIZE);
85 }
86
87 static u32
nfsd_cache_hash(__be32 xid,struct nfsd_net * nn)88 nfsd_cache_hash(__be32 xid, struct nfsd_net *nn)
89 {
90 return hash_32(be32_to_cpu(xid), nn->maskbits);
91 }
92
93 static struct svc_cacherep *
nfsd_reply_cache_alloc(struct svc_rqst * rqstp,__wsum csum,struct nfsd_net * nn)94 nfsd_reply_cache_alloc(struct svc_rqst *rqstp, __wsum csum,
95 struct nfsd_net *nn)
96 {
97 struct svc_cacherep *rp;
98
99 rp = kmem_cache_alloc(drc_slab, GFP_KERNEL);
100 if (rp) {
101 rp->c_state = RC_UNUSED;
102 rp->c_type = RC_NOCACHE;
103 RB_CLEAR_NODE(&rp->c_node);
104 INIT_LIST_HEAD(&rp->c_lru);
105
106 memset(&rp->c_key, 0, sizeof(rp->c_key));
107 rp->c_key.k_xid = rqstp->rq_xid;
108 rp->c_key.k_proc = rqstp->rq_proc;
109 rpc_copy_addr((struct sockaddr *)&rp->c_key.k_addr, svc_addr(rqstp));
110 rpc_set_port((struct sockaddr *)&rp->c_key.k_addr, rpc_get_port(svc_addr(rqstp)));
111 rp->c_key.k_prot = rqstp->rq_prot;
112 rp->c_key.k_vers = rqstp->rq_vers;
113 rp->c_key.k_len = rqstp->rq_arg.len;
114 rp->c_key.k_csum = csum;
115 }
116 return rp;
117 }
118
119 static void
nfsd_reply_cache_free_locked(struct nfsd_drc_bucket * b,struct svc_cacherep * rp,struct nfsd_net * nn)120 nfsd_reply_cache_free_locked(struct nfsd_drc_bucket *b, struct svc_cacherep *rp,
121 struct nfsd_net *nn)
122 {
123 if (rp->c_type == RC_REPLBUFF && rp->c_replvec.iov_base) {
124 nfsd_stats_drc_mem_usage_sub(nn, rp->c_replvec.iov_len);
125 kfree(rp->c_replvec.iov_base);
126 }
127 if (rp->c_state != RC_UNUSED) {
128 rb_erase(&rp->c_node, &b->rb_head);
129 list_del(&rp->c_lru);
130 atomic_dec(&nn->num_drc_entries);
131 nfsd_stats_drc_mem_usage_sub(nn, sizeof(*rp));
132 }
133 kmem_cache_free(drc_slab, rp);
134 }
135
136 static void
nfsd_reply_cache_free(struct nfsd_drc_bucket * b,struct svc_cacherep * rp,struct nfsd_net * nn)137 nfsd_reply_cache_free(struct nfsd_drc_bucket *b, struct svc_cacherep *rp,
138 struct nfsd_net *nn)
139 {
140 spin_lock(&b->cache_lock);
141 nfsd_reply_cache_free_locked(b, rp, nn);
142 spin_unlock(&b->cache_lock);
143 }
144
nfsd_drc_slab_create(void)145 int nfsd_drc_slab_create(void)
146 {
147 drc_slab = kmem_cache_create("nfsd_drc",
148 sizeof(struct svc_cacherep), 0, 0, NULL);
149 return drc_slab ? 0: -ENOMEM;
150 }
151
nfsd_drc_slab_free(void)152 void nfsd_drc_slab_free(void)
153 {
154 kmem_cache_destroy(drc_slab);
155 }
156
nfsd_reply_cache_stats_init(struct nfsd_net * nn)157 static int nfsd_reply_cache_stats_init(struct nfsd_net *nn)
158 {
159 return nfsd_percpu_counters_init(nn->counter, NFSD_NET_COUNTERS_NUM);
160 }
161
nfsd_reply_cache_stats_destroy(struct nfsd_net * nn)162 static void nfsd_reply_cache_stats_destroy(struct nfsd_net *nn)
163 {
164 nfsd_percpu_counters_destroy(nn->counter, NFSD_NET_COUNTERS_NUM);
165 }
166
nfsd_reply_cache_init(struct nfsd_net * nn)167 int nfsd_reply_cache_init(struct nfsd_net *nn)
168 {
169 unsigned int hashsize;
170 unsigned int i;
171 int status = 0;
172
173 nn->max_drc_entries = nfsd_cache_size_limit();
174 atomic_set(&nn->num_drc_entries, 0);
175 hashsize = nfsd_hashsize(nn->max_drc_entries);
176 nn->maskbits = ilog2(hashsize);
177
178 status = nfsd_reply_cache_stats_init(nn);
179 if (status)
180 goto out_nomem;
181
182 nn->nfsd_reply_cache_shrinker.scan_objects = nfsd_reply_cache_scan;
183 nn->nfsd_reply_cache_shrinker.count_objects = nfsd_reply_cache_count;
184 nn->nfsd_reply_cache_shrinker.seeks = 1;
185 status = register_shrinker(&nn->nfsd_reply_cache_shrinker);
186 if (status)
187 goto out_stats_destroy;
188
189 nn->drc_hashtbl = kvzalloc(array_size(hashsize,
190 sizeof(*nn->drc_hashtbl)), GFP_KERNEL);
191 if (!nn->drc_hashtbl)
192 goto out_shrinker;
193
194 for (i = 0; i < hashsize; i++) {
195 INIT_LIST_HEAD(&nn->drc_hashtbl[i].lru_head);
196 spin_lock_init(&nn->drc_hashtbl[i].cache_lock);
197 }
198 nn->drc_hashsize = hashsize;
199
200 return 0;
201 out_shrinker:
202 unregister_shrinker(&nn->nfsd_reply_cache_shrinker);
203 out_stats_destroy:
204 nfsd_reply_cache_stats_destroy(nn);
205 out_nomem:
206 printk(KERN_ERR "nfsd: failed to allocate reply cache\n");
207 return -ENOMEM;
208 }
209
nfsd_reply_cache_shutdown(struct nfsd_net * nn)210 void nfsd_reply_cache_shutdown(struct nfsd_net *nn)
211 {
212 struct svc_cacherep *rp;
213 unsigned int i;
214
215 nfsd_reply_cache_stats_destroy(nn);
216 unregister_shrinker(&nn->nfsd_reply_cache_shrinker);
217
218 for (i = 0; i < nn->drc_hashsize; i++) {
219 struct list_head *head = &nn->drc_hashtbl[i].lru_head;
220 while (!list_empty(head)) {
221 rp = list_first_entry(head, struct svc_cacherep, c_lru);
222 nfsd_reply_cache_free_locked(&nn->drc_hashtbl[i],
223 rp, nn);
224 }
225 }
226
227 kvfree(nn->drc_hashtbl);
228 nn->drc_hashtbl = NULL;
229 nn->drc_hashsize = 0;
230
231 }
232
233 /*
234 * Move cache entry to end of LRU list, and queue the cleaner to run if it's
235 * not already scheduled.
236 */
237 static void
lru_put_end(struct nfsd_drc_bucket * b,struct svc_cacherep * rp)238 lru_put_end(struct nfsd_drc_bucket *b, struct svc_cacherep *rp)
239 {
240 rp->c_timestamp = jiffies;
241 list_move_tail(&rp->c_lru, &b->lru_head);
242 }
243
prune_bucket(struct nfsd_drc_bucket * b,struct nfsd_net * nn,unsigned int max)244 static long prune_bucket(struct nfsd_drc_bucket *b, struct nfsd_net *nn,
245 unsigned int max)
246 {
247 struct svc_cacherep *rp, *tmp;
248 long freed = 0;
249
250 list_for_each_entry_safe(rp, tmp, &b->lru_head, c_lru) {
251 /*
252 * Don't free entries attached to calls that are still
253 * in-progress, but do keep scanning the list.
254 */
255 if (rp->c_state == RC_INPROG)
256 continue;
257 if (atomic_read(&nn->num_drc_entries) <= nn->max_drc_entries &&
258 time_before(jiffies, rp->c_timestamp + RC_EXPIRE))
259 break;
260 nfsd_reply_cache_free_locked(b, rp, nn);
261 if (max && freed++ > max)
262 break;
263 }
264 return freed;
265 }
266
nfsd_prune_bucket(struct nfsd_drc_bucket * b,struct nfsd_net * nn)267 static long nfsd_prune_bucket(struct nfsd_drc_bucket *b, struct nfsd_net *nn)
268 {
269 return prune_bucket(b, nn, 3);
270 }
271
272 /*
273 * Walk the LRU list and prune off entries that are older than RC_EXPIRE.
274 * Also prune the oldest ones when the total exceeds the max number of entries.
275 */
276 static long
prune_cache_entries(struct nfsd_net * nn)277 prune_cache_entries(struct nfsd_net *nn)
278 {
279 unsigned int i;
280 long freed = 0;
281
282 for (i = 0; i < nn->drc_hashsize; i++) {
283 struct nfsd_drc_bucket *b = &nn->drc_hashtbl[i];
284
285 if (list_empty(&b->lru_head))
286 continue;
287 spin_lock(&b->cache_lock);
288 freed += prune_bucket(b, nn, 0);
289 spin_unlock(&b->cache_lock);
290 }
291 return freed;
292 }
293
294 static unsigned long
nfsd_reply_cache_count(struct shrinker * shrink,struct shrink_control * sc)295 nfsd_reply_cache_count(struct shrinker *shrink, struct shrink_control *sc)
296 {
297 struct nfsd_net *nn = container_of(shrink,
298 struct nfsd_net, nfsd_reply_cache_shrinker);
299
300 return atomic_read(&nn->num_drc_entries);
301 }
302
303 static unsigned long
nfsd_reply_cache_scan(struct shrinker * shrink,struct shrink_control * sc)304 nfsd_reply_cache_scan(struct shrinker *shrink, struct shrink_control *sc)
305 {
306 struct nfsd_net *nn = container_of(shrink,
307 struct nfsd_net, nfsd_reply_cache_shrinker);
308
309 return prune_cache_entries(nn);
310 }
311 /*
312 * Walk an xdr_buf and get a CRC for at most the first RC_CSUMLEN bytes
313 */
314 static __wsum
nfsd_cache_csum(struct svc_rqst * rqstp)315 nfsd_cache_csum(struct svc_rqst *rqstp)
316 {
317 int idx;
318 unsigned int base;
319 __wsum csum;
320 struct xdr_buf *buf = &rqstp->rq_arg;
321 const unsigned char *p = buf->head[0].iov_base;
322 size_t csum_len = min_t(size_t, buf->head[0].iov_len + buf->page_len,
323 RC_CSUMLEN);
324 size_t len = min(buf->head[0].iov_len, csum_len);
325
326 /* rq_arg.head first */
327 csum = csum_partial(p, len, 0);
328 csum_len -= len;
329
330 /* Continue into page array */
331 idx = buf->page_base / PAGE_SIZE;
332 base = buf->page_base & ~PAGE_MASK;
333 while (csum_len) {
334 p = page_address(buf->pages[idx]) + base;
335 len = min_t(size_t, PAGE_SIZE - base, csum_len);
336 csum = csum_partial(p, len, csum);
337 csum_len -= len;
338 base = 0;
339 ++idx;
340 }
341 return csum;
342 }
343
344 static int
nfsd_cache_key_cmp(const struct svc_cacherep * key,const struct svc_cacherep * rp,struct nfsd_net * nn)345 nfsd_cache_key_cmp(const struct svc_cacherep *key,
346 const struct svc_cacherep *rp, struct nfsd_net *nn)
347 {
348 if (key->c_key.k_xid == rp->c_key.k_xid &&
349 key->c_key.k_csum != rp->c_key.k_csum) {
350 nfsd_stats_payload_misses_inc(nn);
351 trace_nfsd_drc_mismatch(nn, key, rp);
352 }
353
354 return memcmp(&key->c_key, &rp->c_key, sizeof(key->c_key));
355 }
356
357 /*
358 * Search the request hash for an entry that matches the given rqstp.
359 * Must be called with cache_lock held. Returns the found entry or
360 * inserts an empty key on failure.
361 */
362 static struct svc_cacherep *
nfsd_cache_insert(struct nfsd_drc_bucket * b,struct svc_cacherep * key,struct nfsd_net * nn)363 nfsd_cache_insert(struct nfsd_drc_bucket *b, struct svc_cacherep *key,
364 struct nfsd_net *nn)
365 {
366 struct svc_cacherep *rp, *ret = key;
367 struct rb_node **p = &b->rb_head.rb_node,
368 *parent = NULL;
369 unsigned int entries = 0;
370 int cmp;
371
372 while (*p != NULL) {
373 ++entries;
374 parent = *p;
375 rp = rb_entry(parent, struct svc_cacherep, c_node);
376
377 cmp = nfsd_cache_key_cmp(key, rp, nn);
378 if (cmp < 0)
379 p = &parent->rb_left;
380 else if (cmp > 0)
381 p = &parent->rb_right;
382 else {
383 ret = rp;
384 goto out;
385 }
386 }
387 rb_link_node(&key->c_node, parent, p);
388 rb_insert_color(&key->c_node, &b->rb_head);
389 out:
390 /* tally hash chain length stats */
391 if (entries > nn->longest_chain) {
392 nn->longest_chain = entries;
393 nn->longest_chain_cachesize = atomic_read(&nn->num_drc_entries);
394 } else if (entries == nn->longest_chain) {
395 /* prefer to keep the smallest cachesize possible here */
396 nn->longest_chain_cachesize = min_t(unsigned int,
397 nn->longest_chain_cachesize,
398 atomic_read(&nn->num_drc_entries));
399 }
400
401 lru_put_end(b, ret);
402 return ret;
403 }
404
405 /**
406 * nfsd_cache_lookup - Find an entry in the duplicate reply cache
407 * @rqstp: Incoming Call to find
408 *
409 * Try to find an entry matching the current call in the cache. When none
410 * is found, we try to grab the oldest expired entry off the LRU list. If
411 * a suitable one isn't there, then drop the cache_lock and allocate a
412 * new one, then search again in case one got inserted while this thread
413 * didn't hold the lock.
414 *
415 * Return values:
416 * %RC_DOIT: Process the request normally
417 * %RC_REPLY: Reply from cache
418 * %RC_DROPIT: Do not process the request further
419 */
nfsd_cache_lookup(struct svc_rqst * rqstp)420 int nfsd_cache_lookup(struct svc_rqst *rqstp)
421 {
422 struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
423 struct svc_cacherep *rp, *found;
424 __be32 xid = rqstp->rq_xid;
425 __wsum csum;
426 u32 hash = nfsd_cache_hash(xid, nn);
427 struct nfsd_drc_bucket *b = &nn->drc_hashtbl[hash];
428 int type = rqstp->rq_cachetype;
429 int rtn = RC_DOIT;
430
431 rqstp->rq_cacherep = NULL;
432 if (type == RC_NOCACHE) {
433 nfsd_stats_rc_nocache_inc();
434 goto out;
435 }
436
437 csum = nfsd_cache_csum(rqstp);
438
439 /*
440 * Since the common case is a cache miss followed by an insert,
441 * preallocate an entry.
442 */
443 rp = nfsd_reply_cache_alloc(rqstp, csum, nn);
444 if (!rp)
445 goto out;
446
447 spin_lock(&b->cache_lock);
448 found = nfsd_cache_insert(b, rp, nn);
449 if (found != rp) {
450 nfsd_reply_cache_free_locked(NULL, rp, nn);
451 rp = found;
452 goto found_entry;
453 }
454
455 nfsd_stats_rc_misses_inc();
456 rqstp->rq_cacherep = rp;
457 rp->c_state = RC_INPROG;
458
459 atomic_inc(&nn->num_drc_entries);
460 nfsd_stats_drc_mem_usage_add(nn, sizeof(*rp));
461
462 nfsd_prune_bucket(b, nn);
463
464 out_unlock:
465 spin_unlock(&b->cache_lock);
466 out:
467 return rtn;
468
469 found_entry:
470 /* We found a matching entry which is either in progress or done. */
471 nfsd_stats_rc_hits_inc();
472 rtn = RC_DROPIT;
473
474 /* Request being processed */
475 if (rp->c_state == RC_INPROG)
476 goto out_trace;
477
478 /* From the hall of fame of impractical attacks:
479 * Is this a user who tries to snoop on the cache? */
480 rtn = RC_DOIT;
481 if (!test_bit(RQ_SECURE, &rqstp->rq_flags) && rp->c_secure)
482 goto out_trace;
483
484 /* Compose RPC reply header */
485 switch (rp->c_type) {
486 case RC_NOCACHE:
487 break;
488 case RC_REPLSTAT:
489 svc_putu32(&rqstp->rq_res.head[0], rp->c_replstat);
490 rtn = RC_REPLY;
491 break;
492 case RC_REPLBUFF:
493 if (!nfsd_cache_append(rqstp, &rp->c_replvec))
494 goto out_unlock; /* should not happen */
495 rtn = RC_REPLY;
496 break;
497 default:
498 WARN_ONCE(1, "nfsd: bad repcache type %d\n", rp->c_type);
499 }
500
501 out_trace:
502 trace_nfsd_drc_found(nn, rqstp, rtn);
503 goto out_unlock;
504 }
505
506 /**
507 * nfsd_cache_update - Update an entry in the duplicate reply cache.
508 * @rqstp: svc_rqst with a finished Reply
509 * @cachetype: which cache to update
510 * @statp: Reply's status code
511 *
512 * This is called from nfsd_dispatch when the procedure has been
513 * executed and the complete reply is in rqstp->rq_res.
514 *
515 * We're copying around data here rather than swapping buffers because
516 * the toplevel loop requires max-sized buffers, which would be a waste
517 * of memory for a cache with a max reply size of 100 bytes (diropokres).
518 *
519 * If we should start to use different types of cache entries tailored
520 * specifically for attrstat and fh's, we may save even more space.
521 *
522 * Also note that a cachetype of RC_NOCACHE can legally be passed when
523 * nfsd failed to encode a reply that otherwise would have been cached.
524 * In this case, nfsd_cache_update is called with statp == NULL.
525 */
nfsd_cache_update(struct svc_rqst * rqstp,int cachetype,__be32 * statp)526 void nfsd_cache_update(struct svc_rqst *rqstp, int cachetype, __be32 *statp)
527 {
528 struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
529 struct svc_cacherep *rp = rqstp->rq_cacherep;
530 struct kvec *resv = &rqstp->rq_res.head[0], *cachv;
531 u32 hash;
532 struct nfsd_drc_bucket *b;
533 int len;
534 size_t bufsize = 0;
535
536 if (!rp)
537 return;
538
539 hash = nfsd_cache_hash(rp->c_key.k_xid, nn);
540 b = &nn->drc_hashtbl[hash];
541
542 len = resv->iov_len - ((char*)statp - (char*)resv->iov_base);
543 len >>= 2;
544
545 /* Don't cache excessive amounts of data and XDR failures */
546 if (!statp || len > (256 >> 2)) {
547 nfsd_reply_cache_free(b, rp, nn);
548 return;
549 }
550
551 switch (cachetype) {
552 case RC_REPLSTAT:
553 if (len != 1)
554 printk("nfsd: RC_REPLSTAT/reply len %d!\n",len);
555 rp->c_replstat = *statp;
556 break;
557 case RC_REPLBUFF:
558 cachv = &rp->c_replvec;
559 bufsize = len << 2;
560 cachv->iov_base = kmalloc(bufsize, GFP_KERNEL);
561 if (!cachv->iov_base) {
562 nfsd_reply_cache_free(b, rp, nn);
563 return;
564 }
565 cachv->iov_len = bufsize;
566 memcpy(cachv->iov_base, statp, bufsize);
567 break;
568 case RC_NOCACHE:
569 nfsd_reply_cache_free(b, rp, nn);
570 return;
571 }
572 spin_lock(&b->cache_lock);
573 nfsd_stats_drc_mem_usage_add(nn, bufsize);
574 lru_put_end(b, rp);
575 rp->c_secure = test_bit(RQ_SECURE, &rqstp->rq_flags);
576 rp->c_type = cachetype;
577 rp->c_state = RC_DONE;
578 spin_unlock(&b->cache_lock);
579 return;
580 }
581
582 /*
583 * Copy cached reply to current reply buffer. Should always fit.
584 * FIXME as reply is in a page, we should just attach the page, and
585 * keep a refcount....
586 */
587 static int
nfsd_cache_append(struct svc_rqst * rqstp,struct kvec * data)588 nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *data)
589 {
590 struct kvec *vec = &rqstp->rq_res.head[0];
591
592 if (vec->iov_len + data->iov_len > PAGE_SIZE) {
593 printk(KERN_WARNING "nfsd: cached reply too large (%zd).\n",
594 data->iov_len);
595 return 0;
596 }
597 memcpy((char*)vec->iov_base + vec->iov_len, data->iov_base, data->iov_len);
598 vec->iov_len += data->iov_len;
599 return 1;
600 }
601
602 /*
603 * Note that fields may be added, removed or reordered in the future. Programs
604 * scraping this file for info should test the labels to ensure they're
605 * getting the correct field.
606 */
nfsd_reply_cache_stats_show(struct seq_file * m,void * v)607 static int nfsd_reply_cache_stats_show(struct seq_file *m, void *v)
608 {
609 struct nfsd_net *nn = m->private;
610
611 seq_printf(m, "max entries: %u\n", nn->max_drc_entries);
612 seq_printf(m, "num entries: %u\n",
613 atomic_read(&nn->num_drc_entries));
614 seq_printf(m, "hash buckets: %u\n", 1 << nn->maskbits);
615 seq_printf(m, "mem usage: %lld\n",
616 percpu_counter_sum_positive(&nn->counter[NFSD_NET_DRC_MEM_USAGE]));
617 seq_printf(m, "cache hits: %lld\n",
618 percpu_counter_sum_positive(&nfsdstats.counter[NFSD_STATS_RC_HITS]));
619 seq_printf(m, "cache misses: %lld\n",
620 percpu_counter_sum_positive(&nfsdstats.counter[NFSD_STATS_RC_MISSES]));
621 seq_printf(m, "not cached: %lld\n",
622 percpu_counter_sum_positive(&nfsdstats.counter[NFSD_STATS_RC_NOCACHE]));
623 seq_printf(m, "payload misses: %lld\n",
624 percpu_counter_sum_positive(&nn->counter[NFSD_NET_PAYLOAD_MISSES]));
625 seq_printf(m, "longest chain len: %u\n", nn->longest_chain);
626 seq_printf(m, "cachesize at longest: %u\n", nn->longest_chain_cachesize);
627 return 0;
628 }
629
nfsd_reply_cache_stats_open(struct inode * inode,struct file * file)630 int nfsd_reply_cache_stats_open(struct inode *inode, struct file *file)
631 {
632 struct nfsd_net *nn = net_generic(file_inode(file)->i_sb->s_fs_info,
633 nfsd_net_id);
634
635 return single_open(file, nfsd_reply_cache_stats_show, nn);
636 }
637