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