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1/*
2 * Request reply cache. This is currently a global cache, but this may
3 * change in the future and be a per-client cache.
4 *
5 * This code is heavily inspired by the 44BSD implementation, although
6 * it does things a bit differently.
7 *
8 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
9 */
10
11#include <linux/slab.h>
12#include <linux/sunrpc/addr.h>
13#include <linux/highmem.h>
14#include <linux/log2.h>
15#include <linux/hash.h>
16#include <net/checksum.h>
17
18#include "nfsd.h"
19#include "cache.h"
20
21#define NFSDDBG_FACILITY NFSDDBG_REPCACHE
22
23/*
24 * We use this value to determine the number of hash buckets from the max
25 * cache size, the idea being that when the cache is at its maximum number
26 * of entries, then this should be the average number of entries per bucket.
27 */
28#define TARGET_BUCKET_SIZE 64
29
30static struct hlist_head * cache_hash;
31static struct list_head lru_head;
32static struct kmem_cache *drc_slab;
33
34/* max number of entries allowed in the cache */
35static unsigned int max_drc_entries;
36
37/* number of significant bits in the hash value */
38static unsigned int maskbits;
39
40/*
41 * Stats and other tracking of on the duplicate reply cache. All of these and
42 * the "rc" fields in nfsdstats are protected by the cache_lock
43 */
44
45/* total number of entries */
46static unsigned int num_drc_entries;
47
48/* cache misses due only to checksum comparison failures */
49static unsigned int payload_misses;
50
51/* amount of memory (in bytes) currently consumed by the DRC */
52static unsigned int drc_mem_usage;
53
54/* longest hash chain seen */
55static unsigned int longest_chain;
56
57/* size of cache when we saw the longest hash chain */
58static unsigned int longest_chain_cachesize;
59
60static int nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *vec);
61static void cache_cleaner_func(struct work_struct *unused);
62static unsigned long nfsd_reply_cache_count(struct shrinker *shrink,
63 struct shrink_control *sc);
64static unsigned long nfsd_reply_cache_scan(struct shrinker *shrink,
65 struct shrink_control *sc);
66
67static struct shrinker nfsd_reply_cache_shrinker = {
68 .scan_objects = nfsd_reply_cache_scan,
69 .count_objects = nfsd_reply_cache_count,
70 .seeks = 1,
71};
72
73/*
74 * locking for the reply cache:
75 * A cache entry is "single use" if c_state == RC_INPROG
76 * Otherwise, it when accessing _prev or _next, the lock must be held.
77 */
78static DEFINE_SPINLOCK(cache_lock);
79static DECLARE_DELAYED_WORK(cache_cleaner, cache_cleaner_func);
80
81/*
82 * Put a cap on the size of the DRC based on the amount of available
83 * low memory in the machine.
84 *
85 * 64MB: 8192
86 * 128MB: 11585
87 * 256MB: 16384
88 * 512MB: 23170
89 * 1GB: 32768
90 * 2GB: 46340
91 * 4GB: 65536
92 * 8GB: 92681
93 * 16GB: 131072
94 *
95 * ...with a hard cap of 256k entries. In the worst case, each entry will be
96 * ~1k, so the above numbers should give a rough max of the amount of memory
97 * used in k.
98 */
99static unsigned int
100nfsd_cache_size_limit(void)
101{
102 unsigned int limit;
103 unsigned long low_pages = totalram_pages - totalhigh_pages;
104
105 limit = (16 * int_sqrt(low_pages)) << (PAGE_SHIFT-10);
106 return min_t(unsigned int, limit, 256*1024);
107}
108
109/*
110 * Compute the number of hash buckets we need. Divide the max cachesize by
111 * the "target" max bucket size, and round up to next power of two.
112 */
113static unsigned int
114nfsd_hashsize(unsigned int limit)
115{
116 return roundup_pow_of_two(limit / TARGET_BUCKET_SIZE);
117}
118
119static struct svc_cacherep *
120nfsd_reply_cache_alloc(void)
121{
122 struct svc_cacherep *rp;
123
124 rp = kmem_cache_alloc(drc_slab, GFP_KERNEL);
125 if (rp) {
126 rp->c_state = RC_UNUSED;
127 rp->c_type = RC_NOCACHE;
128 INIT_LIST_HEAD(&rp->c_lru);
129 INIT_HLIST_NODE(&rp->c_hash);
130 }
131 return rp;
132}
133
134static void
135nfsd_reply_cache_free_locked(struct svc_cacherep *rp)
136{
137 if (rp->c_type == RC_REPLBUFF && rp->c_replvec.iov_base) {
138 drc_mem_usage -= rp->c_replvec.iov_len;
139 kfree(rp->c_replvec.iov_base);
140 }
141 if (!hlist_unhashed(&rp->c_hash))
142 hlist_del(&rp->c_hash);
143 list_del(&rp->c_lru);
144 --num_drc_entries;
145 drc_mem_usage -= sizeof(*rp);
146 kmem_cache_free(drc_slab, rp);
147}
148
149static void
150nfsd_reply_cache_free(struct svc_cacherep *rp)
151{
152 spin_lock(&cache_lock);
153 nfsd_reply_cache_free_locked(rp);
154 spin_unlock(&cache_lock);
155}
156
157int nfsd_reply_cache_init(void)
158{
159 unsigned int hashsize;
160
161 INIT_LIST_HEAD(&lru_head);
162 max_drc_entries = nfsd_cache_size_limit();
163 num_drc_entries = 0;
164 hashsize = nfsd_hashsize(max_drc_entries);
165 maskbits = ilog2(hashsize);
166
167 register_shrinker(&nfsd_reply_cache_shrinker);
168 drc_slab = kmem_cache_create("nfsd_drc", sizeof(struct svc_cacherep),
169 0, 0, NULL);
170 if (!drc_slab)
171 goto out_nomem;
172
173 cache_hash = kcalloc(hashsize, sizeof(struct hlist_head), GFP_KERNEL);
174 if (!cache_hash)
175 goto out_nomem;
176
177 return 0;
178out_nomem:
179 printk(KERN_ERR "nfsd: failed to allocate reply cache\n");
180 nfsd_reply_cache_shutdown();
181 return -ENOMEM;
182}
183
184void nfsd_reply_cache_shutdown(void)
185{
186 struct svc_cacherep *rp;
187
188 unregister_shrinker(&nfsd_reply_cache_shrinker);
189 cancel_delayed_work_sync(&cache_cleaner);
190
191 while (!list_empty(&lru_head)) {
192 rp = list_entry(lru_head.next, struct svc_cacherep, c_lru);
193 nfsd_reply_cache_free_locked(rp);
194 }
195
196 kfree (cache_hash);
197 cache_hash = NULL;
198
199 if (drc_slab) {
200 kmem_cache_destroy(drc_slab);
201 drc_slab = NULL;
202 }
203}
204
205/*
206 * Move cache entry to end of LRU list, and queue the cleaner to run if it's
207 * not already scheduled.
208 */
209static void
210lru_put_end(struct svc_cacherep *rp)
211{
212 rp->c_timestamp = jiffies;
213 list_move_tail(&rp->c_lru, &lru_head);
214 schedule_delayed_work(&cache_cleaner, RC_EXPIRE);
215}
216
217/*
218 * Move a cache entry from one hash list to another
219 */
220static void
221hash_refile(struct svc_cacherep *rp)
222{
223 hlist_del_init(&rp->c_hash);
224 hlist_add_head(&rp->c_hash, cache_hash + hash_32(rp->c_xid, maskbits));
225}
226
227static inline bool
228nfsd_cache_entry_expired(struct svc_cacherep *rp)
229{
230 return rp->c_state != RC_INPROG &&
231 time_after(jiffies, rp->c_timestamp + RC_EXPIRE);
232}
233
234/*
235 * Walk the LRU list and prune off entries that are older than RC_EXPIRE.
236 * Also prune the oldest ones when the total exceeds the max number of entries.
237 */
238static long
239prune_cache_entries(void)
240{
241 struct svc_cacherep *rp, *tmp;
242 long freed = 0;
243
244 list_for_each_entry_safe(rp, tmp, &lru_head, c_lru) {
245 if (!nfsd_cache_entry_expired(rp) &&
246 num_drc_entries <= max_drc_entries)
247 break;
248 nfsd_reply_cache_free_locked(rp);
249 freed++;
250 }
251
252 /*
253 * Conditionally rearm the job. If we cleaned out the list, then
254 * cancel any pending run (since there won't be any work to do).
255 * Otherwise, we rearm the job or modify the existing one to run in
256 * RC_EXPIRE since we just ran the pruner.
257 */
258 if (list_empty(&lru_head))
259 cancel_delayed_work(&cache_cleaner);
260 else
261 mod_delayed_work(system_wq, &cache_cleaner, RC_EXPIRE);
262 return freed;
263}
264
265static void
266cache_cleaner_func(struct work_struct *unused)
267{
268 spin_lock(&cache_lock);
269 prune_cache_entries();
270 spin_unlock(&cache_lock);
271}
272
273static unsigned long
274nfsd_reply_cache_count(struct shrinker *shrink, struct shrink_control *sc)
275{
276 unsigned long num;
277
278 spin_lock(&cache_lock);
279 num = num_drc_entries;
280 spin_unlock(&cache_lock);
281
282 return num;
283}
284
285static unsigned long
286nfsd_reply_cache_scan(struct shrinker *shrink, struct shrink_control *sc)
287{
288 unsigned long freed;
289
290 spin_lock(&cache_lock);
291 freed = prune_cache_entries();
292 spin_unlock(&cache_lock);
293 return freed;
294}
295/*
296 * Walk an xdr_buf and get a CRC for at most the first RC_CSUMLEN bytes
297 */
298static __wsum
299nfsd_cache_csum(struct svc_rqst *rqstp)
300{
301 int idx;
302 unsigned int base;
303 __wsum csum;
304 struct xdr_buf *buf = &rqstp->rq_arg;
305 const unsigned char *p = buf->head[0].iov_base;
306 size_t csum_len = min_t(size_t, buf->head[0].iov_len + buf->page_len,
307 RC_CSUMLEN);
308 size_t len = min(buf->head[0].iov_len, csum_len);
309
310 /* rq_arg.head first */
311 csum = csum_partial(p, len, 0);
312 csum_len -= len;
313
314 /* Continue into page array */
315 idx = buf->page_base / PAGE_SIZE;
316 base = buf->page_base & ~PAGE_MASK;
317 while (csum_len) {
318 p = page_address(buf->pages[idx]) + base;
319 len = min_t(size_t, PAGE_SIZE - base, csum_len);
320 csum = csum_partial(p, len, csum);
321 csum_len -= len;
322 base = 0;
323 ++idx;
324 }
325 return csum;
326}
327
328static bool
329nfsd_cache_match(struct svc_rqst *rqstp, __wsum csum, struct svc_cacherep *rp)
330{
331 /* Check RPC header info first */
332 if (rqstp->rq_xid != rp->c_xid || rqstp->rq_proc != rp->c_proc ||
333 rqstp->rq_prot != rp->c_prot || rqstp->rq_vers != rp->c_vers ||
334 rqstp->rq_arg.len != rp->c_len ||
335 !rpc_cmp_addr(svc_addr(rqstp), (struct sockaddr *)&rp->c_addr) ||
336 rpc_get_port(svc_addr(rqstp)) != rpc_get_port((struct sockaddr *)&rp->c_addr))
337 return false;
338
339 /* compare checksum of NFS data */
340 if (csum != rp->c_csum) {
341 ++payload_misses;
342 return false;
343 }
344
345 return true;
346}
347
348/*
349 * Search the request hash for an entry that matches the given rqstp.
350 * Must be called with cache_lock held. Returns the found entry or
351 * NULL on failure.
352 */
353static struct svc_cacherep *
354nfsd_cache_search(struct svc_rqst *rqstp, __wsum csum)
355{
356 struct svc_cacherep *rp, *ret = NULL;
357 struct hlist_head *rh;
358 unsigned int entries = 0;
359
360 rh = &cache_hash[hash_32(rqstp->rq_xid, maskbits)];
361 hlist_for_each_entry(rp, rh, c_hash) {
362 ++entries;
363 if (nfsd_cache_match(rqstp, csum, rp)) {
364 ret = rp;
365 break;
366 }
367 }
368
369 /* tally hash chain length stats */
370 if (entries > longest_chain) {
371 longest_chain = entries;
372 longest_chain_cachesize = num_drc_entries;
373 } else if (entries == longest_chain) {
374 /* prefer to keep the smallest cachesize possible here */
375 longest_chain_cachesize = min(longest_chain_cachesize,
376 num_drc_entries);
377 }
378
379 return ret;
380}
381
382/*
383 * Try to find an entry matching the current call in the cache. When none
384 * is found, we try to grab the oldest expired entry off the LRU list. If
385 * a suitable one isn't there, then drop the cache_lock and allocate a
386 * new one, then search again in case one got inserted while this thread
387 * didn't hold the lock.
388 */
389int
390nfsd_cache_lookup(struct svc_rqst *rqstp)
391{
392 struct svc_cacherep *rp, *found;
393 __be32 xid = rqstp->rq_xid;
394 u32 proto = rqstp->rq_prot,
395 vers = rqstp->rq_vers,
396 proc = rqstp->rq_proc;
397 __wsum csum;
398 unsigned long age;
399 int type = rqstp->rq_cachetype;
400 int rtn = RC_DOIT;
401
402 rqstp->rq_cacherep = NULL;
403 if (type == RC_NOCACHE) {
404 nfsdstats.rcnocache++;
405 return rtn;
406 }
407
408 csum = nfsd_cache_csum(rqstp);
409
410 /*
411 * Since the common case is a cache miss followed by an insert,
412 * preallocate an entry.
413 */
414 rp = nfsd_reply_cache_alloc();
415 spin_lock(&cache_lock);
416 if (likely(rp)) {
417 ++num_drc_entries;
418 drc_mem_usage += sizeof(*rp);
419 }
420
421 /* go ahead and prune the cache */
422 prune_cache_entries();
423
424 found = nfsd_cache_search(rqstp, csum);
425 if (found) {
426 if (likely(rp))
427 nfsd_reply_cache_free_locked(rp);
428 rp = found;
429 goto found_entry;
430 }
431
432 if (!rp) {
433 dprintk("nfsd: unable to allocate DRC entry!\n");
434 goto out;
435 }
436
437 nfsdstats.rcmisses++;
438 rqstp->rq_cacherep = rp;
439 rp->c_state = RC_INPROG;
440 rp->c_xid = xid;
441 rp->c_proc = proc;
442 rpc_copy_addr((struct sockaddr *)&rp->c_addr, svc_addr(rqstp));
443 rpc_set_port((struct sockaddr *)&rp->c_addr, rpc_get_port(svc_addr(rqstp)));
444 rp->c_prot = proto;
445 rp->c_vers = vers;
446 rp->c_len = rqstp->rq_arg.len;
447 rp->c_csum = csum;
448
449 hash_refile(rp);
450 lru_put_end(rp);
451
452 /* release any buffer */
453 if (rp->c_type == RC_REPLBUFF) {
454 drc_mem_usage -= rp->c_replvec.iov_len;
455 kfree(rp->c_replvec.iov_base);
456 rp->c_replvec.iov_base = NULL;
457 }
458 rp->c_type = RC_NOCACHE;
459 out:
460 spin_unlock(&cache_lock);
461 return rtn;
462
463found_entry:
464 nfsdstats.rchits++;
465 /* We found a matching entry which is either in progress or done. */
466 age = jiffies - rp->c_timestamp;
467 lru_put_end(rp);
468
469 rtn = RC_DROPIT;
470 /* Request being processed or excessive rexmits */
471 if (rp->c_state == RC_INPROG || age < RC_DELAY)
472 goto out;
473
474 /* From the hall of fame of impractical attacks:
475 * Is this a user who tries to snoop on the cache? */
476 rtn = RC_DOIT;
477 if (!rqstp->rq_secure && rp->c_secure)
478 goto out;
479
480 /* Compose RPC reply header */
481 switch (rp->c_type) {
482 case RC_NOCACHE:
483 break;
484 case RC_REPLSTAT:
485 svc_putu32(&rqstp->rq_res.head[0], rp->c_replstat);
486 rtn = RC_REPLY;
487 break;
488 case RC_REPLBUFF:
489 if (!nfsd_cache_append(rqstp, &rp->c_replvec))
490 goto out; /* should not happen */
491 rtn = RC_REPLY;
492 break;
493 default:
494 printk(KERN_WARNING "nfsd: bad repcache type %d\n", rp->c_type);
495 nfsd_reply_cache_free_locked(rp);
496 }
497
498 goto out;
499}
500
501/*
502 * Update a cache entry. This is called from nfsd_dispatch when
503 * the procedure has been executed and the complete reply is in
504 * rqstp->rq_res.
505 *
506 * We're copying around data here rather than swapping buffers because
507 * the toplevel loop requires max-sized buffers, which would be a waste
508 * of memory for a cache with a max reply size of 100 bytes (diropokres).
509 *
510 * If we should start to use different types of cache entries tailored
511 * specifically for attrstat and fh's, we may save even more space.
512 *
513 * Also note that a cachetype of RC_NOCACHE can legally be passed when
514 * nfsd failed to encode a reply that otherwise would have been cached.
515 * In this case, nfsd_cache_update is called with statp == NULL.
516 */
517void
518nfsd_cache_update(struct svc_rqst *rqstp, int cachetype, __be32 *statp)
519{
520 struct svc_cacherep *rp = rqstp->rq_cacherep;
521 struct kvec *resv = &rqstp->rq_res.head[0], *cachv;
522 int len;
523 size_t bufsize = 0;
524
525 if (!rp)
526 return;
527
528 len = resv->iov_len - ((char*)statp - (char*)resv->iov_base);
529 len >>= 2;
530
531 /* Don't cache excessive amounts of data and XDR failures */
532 if (!statp || len > (256 >> 2)) {
533 nfsd_reply_cache_free(rp);
534 return;
535 }
536
537 switch (cachetype) {
538 case RC_REPLSTAT:
539 if (len != 1)
540 printk("nfsd: RC_REPLSTAT/reply len %d!\n",len);
541 rp->c_replstat = *statp;
542 break;
543 case RC_REPLBUFF:
544 cachv = &rp->c_replvec;
545 bufsize = len << 2;
546 cachv->iov_base = kmalloc(bufsize, GFP_KERNEL);
547 if (!cachv->iov_base) {
548 nfsd_reply_cache_free(rp);
549 return;
550 }
551 cachv->iov_len = bufsize;
552 memcpy(cachv->iov_base, statp, bufsize);
553 break;
554 case RC_NOCACHE:
555 nfsd_reply_cache_free(rp);
556 return;
557 }
558 spin_lock(&cache_lock);
559 drc_mem_usage += bufsize;
560 lru_put_end(rp);
561 rp->c_secure = rqstp->rq_secure;
562 rp->c_type = cachetype;
563 rp->c_state = RC_DONE;
564 spin_unlock(&cache_lock);
565 return;
566}
567
568/*
569 * Copy cached reply to current reply buffer. Should always fit.
570 * FIXME as reply is in a page, we should just attach the page, and
571 * keep a refcount....
572 */
573static int
574nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *data)
575{
576 struct kvec *vec = &rqstp->rq_res.head[0];
577
578 if (vec->iov_len + data->iov_len > PAGE_SIZE) {
579 printk(KERN_WARNING "nfsd: cached reply too large (%Zd).\n",
580 data->iov_len);
581 return 0;
582 }
583 memcpy((char*)vec->iov_base + vec->iov_len, data->iov_base, data->iov_len);
584 vec->iov_len += data->iov_len;
585 return 1;
586}
587
588/*
589 * Note that fields may be added, removed or reordered in the future. Programs
590 * scraping this file for info should test the labels to ensure they're
591 * getting the correct field.
592 */
593static int nfsd_reply_cache_stats_show(struct seq_file *m, void *v)
594{
595 spin_lock(&cache_lock);
596 seq_printf(m, "max entries: %u\n", max_drc_entries);
597 seq_printf(m, "num entries: %u\n", num_drc_entries);
598 seq_printf(m, "hash buckets: %u\n", 1 << maskbits);
599 seq_printf(m, "mem usage: %u\n", drc_mem_usage);
600 seq_printf(m, "cache hits: %u\n", nfsdstats.rchits);
601 seq_printf(m, "cache misses: %u\n", nfsdstats.rcmisses);
602 seq_printf(m, "not cached: %u\n", nfsdstats.rcnocache);
603 seq_printf(m, "payload misses: %u\n", payload_misses);
604 seq_printf(m, "longest chain len: %u\n", longest_chain);
605 seq_printf(m, "cachesize at longest: %u\n", longest_chain_cachesize);
606 spin_unlock(&cache_lock);
607 return 0;
608}
609
610int nfsd_reply_cache_stats_open(struct inode *inode, struct file *file)
611{
612 return single_open(file, nfsd_reply_cache_stats_show, NULL);
613}
1/*
2 * Request reply cache. This is currently a global cache, but this may
3 * change in the future and be a per-client cache.
4 *
5 * This code is heavily inspired by the 44BSD implementation, although
6 * it does things a bit differently.
7 *
8 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
9 */
10
11#include <linux/slab.h>
12
13#include "nfsd.h"
14#include "cache.h"
15
16/* Size of reply cache. Common values are:
17 * 4.3BSD: 128
18 * 4.4BSD: 256
19 * Solaris2: 1024
20 * DEC Unix: 512-4096
21 */
22#define CACHESIZE 1024
23#define HASHSIZE 64
24
25static struct hlist_head * cache_hash;
26static struct list_head lru_head;
27static int cache_disabled = 1;
28
29/*
30 * Calculate the hash index from an XID.
31 */
32static inline u32 request_hash(u32 xid)
33{
34 u32 h = xid;
35 h ^= (xid >> 24);
36 return h & (HASHSIZE-1);
37}
38
39static int nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *vec);
40
41/*
42 * locking for the reply cache:
43 * A cache entry is "single use" if c_state == RC_INPROG
44 * Otherwise, it when accessing _prev or _next, the lock must be held.
45 */
46static DEFINE_SPINLOCK(cache_lock);
47
48int nfsd_reply_cache_init(void)
49{
50 struct svc_cacherep *rp;
51 int i;
52
53 INIT_LIST_HEAD(&lru_head);
54 i = CACHESIZE;
55 while (i) {
56 rp = kmalloc(sizeof(*rp), GFP_KERNEL);
57 if (!rp)
58 goto out_nomem;
59 list_add(&rp->c_lru, &lru_head);
60 rp->c_state = RC_UNUSED;
61 rp->c_type = RC_NOCACHE;
62 INIT_HLIST_NODE(&rp->c_hash);
63 i--;
64 }
65
66 cache_hash = kcalloc (HASHSIZE, sizeof(struct hlist_head), GFP_KERNEL);
67 if (!cache_hash)
68 goto out_nomem;
69
70 cache_disabled = 0;
71 return 0;
72out_nomem:
73 printk(KERN_ERR "nfsd: failed to allocate reply cache\n");
74 nfsd_reply_cache_shutdown();
75 return -ENOMEM;
76}
77
78void nfsd_reply_cache_shutdown(void)
79{
80 struct svc_cacherep *rp;
81
82 while (!list_empty(&lru_head)) {
83 rp = list_entry(lru_head.next, struct svc_cacherep, c_lru);
84 if (rp->c_state == RC_DONE && rp->c_type == RC_REPLBUFF)
85 kfree(rp->c_replvec.iov_base);
86 list_del(&rp->c_lru);
87 kfree(rp);
88 }
89
90 cache_disabled = 1;
91
92 kfree (cache_hash);
93 cache_hash = NULL;
94}
95
96/*
97 * Move cache entry to end of LRU list
98 */
99static void
100lru_put_end(struct svc_cacherep *rp)
101{
102 list_move_tail(&rp->c_lru, &lru_head);
103}
104
105/*
106 * Move a cache entry from one hash list to another
107 */
108static void
109hash_refile(struct svc_cacherep *rp)
110{
111 hlist_del_init(&rp->c_hash);
112 hlist_add_head(&rp->c_hash, cache_hash + request_hash(rp->c_xid));
113}
114
115/*
116 * Try to find an entry matching the current call in the cache. When none
117 * is found, we grab the oldest unlocked entry off the LRU list.
118 * Note that no operation within the loop may sleep.
119 */
120int
121nfsd_cache_lookup(struct svc_rqst *rqstp)
122{
123 struct hlist_node *hn;
124 struct hlist_head *rh;
125 struct svc_cacherep *rp;
126 __be32 xid = rqstp->rq_xid;
127 u32 proto = rqstp->rq_prot,
128 vers = rqstp->rq_vers,
129 proc = rqstp->rq_proc;
130 unsigned long age;
131 int type = rqstp->rq_cachetype;
132 int rtn;
133
134 rqstp->rq_cacherep = NULL;
135 if (cache_disabled || type == RC_NOCACHE) {
136 nfsdstats.rcnocache++;
137 return RC_DOIT;
138 }
139
140 spin_lock(&cache_lock);
141 rtn = RC_DOIT;
142
143 rh = &cache_hash[request_hash(xid)];
144 hlist_for_each_entry(rp, hn, rh, c_hash) {
145 if (rp->c_state != RC_UNUSED &&
146 xid == rp->c_xid && proc == rp->c_proc &&
147 proto == rp->c_prot && vers == rp->c_vers &&
148 time_before(jiffies, rp->c_timestamp + 120*HZ) &&
149 memcmp((char*)&rqstp->rq_addr, (char*)&rp->c_addr, sizeof(rp->c_addr))==0) {
150 nfsdstats.rchits++;
151 goto found_entry;
152 }
153 }
154 nfsdstats.rcmisses++;
155
156 /* This loop shouldn't take more than a few iterations normally */
157 {
158 int safe = 0;
159 list_for_each_entry(rp, &lru_head, c_lru) {
160 if (rp->c_state != RC_INPROG)
161 break;
162 if (safe++ > CACHESIZE) {
163 printk("nfsd: loop in repcache LRU list\n");
164 cache_disabled = 1;
165 goto out;
166 }
167 }
168 }
169
170 /* All entries on the LRU are in-progress. This should not happen */
171 if (&rp->c_lru == &lru_head) {
172 static int complaints;
173
174 printk(KERN_WARNING "nfsd: all repcache entries locked!\n");
175 if (++complaints > 5) {
176 printk(KERN_WARNING "nfsd: disabling repcache.\n");
177 cache_disabled = 1;
178 }
179 goto out;
180 }
181
182 rqstp->rq_cacherep = rp;
183 rp->c_state = RC_INPROG;
184 rp->c_xid = xid;
185 rp->c_proc = proc;
186 memcpy(&rp->c_addr, svc_addr_in(rqstp), sizeof(rp->c_addr));
187 rp->c_prot = proto;
188 rp->c_vers = vers;
189 rp->c_timestamp = jiffies;
190
191 hash_refile(rp);
192
193 /* release any buffer */
194 if (rp->c_type == RC_REPLBUFF) {
195 kfree(rp->c_replvec.iov_base);
196 rp->c_replvec.iov_base = NULL;
197 }
198 rp->c_type = RC_NOCACHE;
199 out:
200 spin_unlock(&cache_lock);
201 return rtn;
202
203found_entry:
204 /* We found a matching entry which is either in progress or done. */
205 age = jiffies - rp->c_timestamp;
206 rp->c_timestamp = jiffies;
207 lru_put_end(rp);
208
209 rtn = RC_DROPIT;
210 /* Request being processed or excessive rexmits */
211 if (rp->c_state == RC_INPROG || age < RC_DELAY)
212 goto out;
213
214 /* From the hall of fame of impractical attacks:
215 * Is this a user who tries to snoop on the cache? */
216 rtn = RC_DOIT;
217 if (!rqstp->rq_secure && rp->c_secure)
218 goto out;
219
220 /* Compose RPC reply header */
221 switch (rp->c_type) {
222 case RC_NOCACHE:
223 break;
224 case RC_REPLSTAT:
225 svc_putu32(&rqstp->rq_res.head[0], rp->c_replstat);
226 rtn = RC_REPLY;
227 break;
228 case RC_REPLBUFF:
229 if (!nfsd_cache_append(rqstp, &rp->c_replvec))
230 goto out; /* should not happen */
231 rtn = RC_REPLY;
232 break;
233 default:
234 printk(KERN_WARNING "nfsd: bad repcache type %d\n", rp->c_type);
235 rp->c_state = RC_UNUSED;
236 }
237
238 goto out;
239}
240
241/*
242 * Update a cache entry. This is called from nfsd_dispatch when
243 * the procedure has been executed and the complete reply is in
244 * rqstp->rq_res.
245 *
246 * We're copying around data here rather than swapping buffers because
247 * the toplevel loop requires max-sized buffers, which would be a waste
248 * of memory for a cache with a max reply size of 100 bytes (diropokres).
249 *
250 * If we should start to use different types of cache entries tailored
251 * specifically for attrstat and fh's, we may save even more space.
252 *
253 * Also note that a cachetype of RC_NOCACHE can legally be passed when
254 * nfsd failed to encode a reply that otherwise would have been cached.
255 * In this case, nfsd_cache_update is called with statp == NULL.
256 */
257void
258nfsd_cache_update(struct svc_rqst *rqstp, int cachetype, __be32 *statp)
259{
260 struct svc_cacherep *rp;
261 struct kvec *resv = &rqstp->rq_res.head[0], *cachv;
262 int len;
263
264 if (!(rp = rqstp->rq_cacherep) || cache_disabled)
265 return;
266
267 len = resv->iov_len - ((char*)statp - (char*)resv->iov_base);
268 len >>= 2;
269
270 /* Don't cache excessive amounts of data and XDR failures */
271 if (!statp || len > (256 >> 2)) {
272 rp->c_state = RC_UNUSED;
273 return;
274 }
275
276 switch (cachetype) {
277 case RC_REPLSTAT:
278 if (len != 1)
279 printk("nfsd: RC_REPLSTAT/reply len %d!\n",len);
280 rp->c_replstat = *statp;
281 break;
282 case RC_REPLBUFF:
283 cachv = &rp->c_replvec;
284 cachv->iov_base = kmalloc(len << 2, GFP_KERNEL);
285 if (!cachv->iov_base) {
286 spin_lock(&cache_lock);
287 rp->c_state = RC_UNUSED;
288 spin_unlock(&cache_lock);
289 return;
290 }
291 cachv->iov_len = len << 2;
292 memcpy(cachv->iov_base, statp, len << 2);
293 break;
294 }
295 spin_lock(&cache_lock);
296 lru_put_end(rp);
297 rp->c_secure = rqstp->rq_secure;
298 rp->c_type = cachetype;
299 rp->c_state = RC_DONE;
300 rp->c_timestamp = jiffies;
301 spin_unlock(&cache_lock);
302 return;
303}
304
305/*
306 * Copy cached reply to current reply buffer. Should always fit.
307 * FIXME as reply is in a page, we should just attach the page, and
308 * keep a refcount....
309 */
310static int
311nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *data)
312{
313 struct kvec *vec = &rqstp->rq_res.head[0];
314
315 if (vec->iov_len + data->iov_len > PAGE_SIZE) {
316 printk(KERN_WARNING "nfsd: cached reply too large (%Zd).\n",
317 data->iov_len);
318 return 0;
319 }
320 memcpy((char*)vec->iov_base + vec->iov_len, data->iov_base, data->iov_len);
321 vec->iov_len += data->iov_len;
322 return 1;
323}