Commit | Line | Data |
---|---|---|
1da177e4 | 1 | /* |
1da177e4 LT |
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 | ||
5a0e3ad6 | 11 | #include <linux/slab.h> |
5976687a | 12 | #include <linux/sunrpc/addr.h> |
0338dd15 | 13 | #include <linux/highmem.h> |
0733c7ba JL |
14 | #include <linux/log2.h> |
15 | #include <linux/hash.h> | |
01a7decf | 16 | #include <net/checksum.h> |
5a0e3ad6 | 17 | |
9a74af21 BH |
18 | #include "nfsd.h" |
19 | #include "cache.h" | |
1da177e4 | 20 | |
0338dd15 JL |
21 | #define NFSDDBG_FACILITY NFSDDBG_REPCACHE |
22 | ||
0733c7ba JL |
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 | |
1da177e4 | 29 | |
fca4217c | 30 | static struct hlist_head * cache_hash; |
1da177e4 | 31 | static struct list_head lru_head; |
8a8bc40d | 32 | static struct kmem_cache *drc_slab; |
9dc56143 JL |
33 | |
34 | /* max number of entries allowed in the cache */ | |
0338dd15 | 35 | static unsigned int max_drc_entries; |
1da177e4 | 36 | |
0733c7ba JL |
37 | /* number of significant bits in the hash value */ |
38 | static unsigned int maskbits; | |
39 | ||
9dc56143 JL |
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 */ | |
46 | static unsigned int num_drc_entries; | |
47 | ||
48 | /* cache misses due only to checksum comparison failures */ | |
49 | static unsigned int payload_misses; | |
50 | ||
6c6910cd JL |
51 | /* amount of memory (in bytes) currently consumed by the DRC */ |
52 | static unsigned int drc_mem_usage; | |
53 | ||
98d821bd JL |
54 | /* longest hash chain seen */ |
55 | static unsigned int longest_chain; | |
56 | ||
57 | /* size of cache when we saw the longest hash chain */ | |
58 | static unsigned int longest_chain_cachesize; | |
59 | ||
1da177e4 | 60 | static int nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *vec); |
aca8a23d | 61 | static void cache_cleaner_func(struct work_struct *unused); |
1ab6c499 DC |
62 | static unsigned long nfsd_reply_cache_count(struct shrinker *shrink, |
63 | struct shrink_control *sc); | |
64 | static unsigned long nfsd_reply_cache_scan(struct shrinker *shrink, | |
65 | struct shrink_control *sc); | |
b4e7f2c9 | 66 | |
c8c797f9 | 67 | static struct shrinker nfsd_reply_cache_shrinker = { |
1ab6c499 DC |
68 | .scan_objects = nfsd_reply_cache_scan, |
69 | .count_objects = nfsd_reply_cache_count, | |
b4e7f2c9 JL |
70 | .seeks = 1, |
71 | }; | |
1da177e4 | 72 | |
fca4217c | 73 | /* |
1da177e4 LT |
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 | */ | |
78 | static DEFINE_SPINLOCK(cache_lock); | |
aca8a23d | 79 | static DECLARE_DELAYED_WORK(cache_cleaner, cache_cleaner_func); |
1da177e4 | 80 | |
0338dd15 JL |
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 | */ | |
99 | static unsigned int | |
100 | nfsd_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 | ||
0733c7ba JL |
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 | */ | |
113 | static unsigned int | |
114 | nfsd_hashsize(unsigned int limit) | |
115 | { | |
116 | return roundup_pow_of_two(limit / TARGET_BUCKET_SIZE); | |
117 | } | |
118 | ||
f09841fd JL |
119 | static struct svc_cacherep * |
120 | nfsd_reply_cache_alloc(void) | |
1da177e4 LT |
121 | { |
122 | struct svc_cacherep *rp; | |
1da177e4 | 123 | |
f09841fd JL |
124 | rp = kmem_cache_alloc(drc_slab, GFP_KERNEL); |
125 | if (rp) { | |
1da177e4 LT |
126 | rp->c_state = RC_UNUSED; |
127 | rp->c_type = RC_NOCACHE; | |
f09841fd | 128 | INIT_LIST_HEAD(&rp->c_lru); |
1da177e4 | 129 | INIT_HLIST_NODE(&rp->c_hash); |
1da177e4 | 130 | } |
f09841fd JL |
131 | return rp; |
132 | } | |
1da177e4 | 133 | |
f09841fd JL |
134 | static void |
135 | nfsd_reply_cache_free_locked(struct svc_cacherep *rp) | |
136 | { | |
6c6910cd JL |
137 | if (rp->c_type == RC_REPLBUFF && rp->c_replvec.iov_base) { |
138 | drc_mem_usage -= rp->c_replvec.iov_len; | |
f09841fd | 139 | kfree(rp->c_replvec.iov_base); |
6c6910cd | 140 | } |
a517b608 JL |
141 | if (!hlist_unhashed(&rp->c_hash)) |
142 | hlist_del(&rp->c_hash); | |
f09841fd | 143 | list_del(&rp->c_lru); |
0ee0bf7e | 144 | --num_drc_entries; |
6c6910cd | 145 | drc_mem_usage -= sizeof(*rp); |
f09841fd JL |
146 | kmem_cache_free(drc_slab, rp); |
147 | } | |
148 | ||
2c6b691c JL |
149 | static void |
150 | nfsd_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 | ||
f09841fd JL |
157 | int nfsd_reply_cache_init(void) |
158 | { | |
0733c7ba JL |
159 | unsigned int hashsize; |
160 | ||
ac534ff2 JL |
161 | INIT_LIST_HEAD(&lru_head); |
162 | max_drc_entries = nfsd_cache_size_limit(); | |
163 | num_drc_entries = 0; | |
0733c7ba JL |
164 | hashsize = nfsd_hashsize(max_drc_entries); |
165 | maskbits = ilog2(hashsize); | |
ac534ff2 | 166 | |
b4e7f2c9 | 167 | register_shrinker(&nfsd_reply_cache_shrinker); |
8a8bc40d JL |
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 | ||
0733c7ba | 173 | cache_hash = kcalloc(hashsize, sizeof(struct hlist_head), GFP_KERNEL); |
fca4217c | 174 | if (!cache_hash) |
d5c3428b | 175 | goto out_nomem; |
1da177e4 | 176 | |
d5c3428b BF |
177 | return 0; |
178 | out_nomem: | |
179 | printk(KERN_ERR "nfsd: failed to allocate reply cache\n"); | |
180 | nfsd_reply_cache_shutdown(); | |
181 | return -ENOMEM; | |
1da177e4 LT |
182 | } |
183 | ||
d5c3428b | 184 | void nfsd_reply_cache_shutdown(void) |
1da177e4 LT |
185 | { |
186 | struct svc_cacherep *rp; | |
187 | ||
b4e7f2c9 | 188 | unregister_shrinker(&nfsd_reply_cache_shrinker); |
aca8a23d JL |
189 | cancel_delayed_work_sync(&cache_cleaner); |
190 | ||
1da177e4 LT |
191 | while (!list_empty(&lru_head)) { |
192 | rp = list_entry(lru_head.next, struct svc_cacherep, c_lru); | |
f09841fd | 193 | nfsd_reply_cache_free_locked(rp); |
1da177e4 LT |
194 | } |
195 | ||
fca4217c GB |
196 | kfree (cache_hash); |
197 | cache_hash = NULL; | |
8a8bc40d JL |
198 | |
199 | if (drc_slab) { | |
200 | kmem_cache_destroy(drc_slab); | |
201 | drc_slab = NULL; | |
202 | } | |
1da177e4 LT |
203 | } |
204 | ||
205 | /* | |
aca8a23d JL |
206 | * Move cache entry to end of LRU list, and queue the cleaner to run if it's |
207 | * not already scheduled. | |
1da177e4 LT |
208 | */ |
209 | static void | |
210 | lru_put_end(struct svc_cacherep *rp) | |
211 | { | |
56c2548b | 212 | rp->c_timestamp = jiffies; |
f116629d | 213 | list_move_tail(&rp->c_lru, &lru_head); |
aca8a23d | 214 | schedule_delayed_work(&cache_cleaner, RC_EXPIRE); |
1da177e4 LT |
215 | } |
216 | ||
217 | /* | |
218 | * Move a cache entry from one hash list to another | |
219 | */ | |
220 | static void | |
221 | hash_refile(struct svc_cacherep *rp) | |
222 | { | |
223 | hlist_del_init(&rp->c_hash); | |
b3d8d128 JL |
224 | /* |
225 | * No point in byte swapping c_xid since we're just using it to pick | |
226 | * a hash bucket. | |
227 | */ | |
228 | hlist_add_head(&rp->c_hash, cache_hash + | |
229 | hash_32((__force u32)rp->c_xid, maskbits)); | |
1da177e4 LT |
230 | } |
231 | ||
aca8a23d JL |
232 | /* |
233 | * Walk the LRU list and prune off entries that are older than RC_EXPIRE. | |
234 | * Also prune the oldest ones when the total exceeds the max number of entries. | |
235 | */ | |
1ab6c499 | 236 | static long |
aca8a23d JL |
237 | prune_cache_entries(void) |
238 | { | |
239 | struct svc_cacherep *rp, *tmp; | |
1ab6c499 | 240 | long freed = 0; |
aca8a23d JL |
241 | |
242 | list_for_each_entry_safe(rp, tmp, &lru_head, c_lru) { | |
1b19453d JL |
243 | /* |
244 | * Don't free entries attached to calls that are still | |
245 | * in-progress, but do keep scanning the list. | |
246 | */ | |
247 | if (rp->c_state == RC_INPROG) | |
248 | continue; | |
249 | if (num_drc_entries <= max_drc_entries && | |
250 | time_before(jiffies, rp->c_timestamp + RC_EXPIRE)) | |
aca8a23d JL |
251 | break; |
252 | nfsd_reply_cache_free_locked(rp); | |
1ab6c499 | 253 | freed++; |
aca8a23d JL |
254 | } |
255 | ||
256 | /* | |
257 | * Conditionally rearm the job. If we cleaned out the list, then | |
258 | * cancel any pending run (since there won't be any work to do). | |
259 | * Otherwise, we rearm the job or modify the existing one to run in | |
260 | * RC_EXPIRE since we just ran the pruner. | |
261 | */ | |
262 | if (list_empty(&lru_head)) | |
263 | cancel_delayed_work(&cache_cleaner); | |
264 | else | |
265 | mod_delayed_work(system_wq, &cache_cleaner, RC_EXPIRE); | |
1ab6c499 | 266 | return freed; |
aca8a23d JL |
267 | } |
268 | ||
269 | static void | |
270 | cache_cleaner_func(struct work_struct *unused) | |
271 | { | |
272 | spin_lock(&cache_lock); | |
273 | prune_cache_entries(); | |
274 | spin_unlock(&cache_lock); | |
275 | } | |
276 | ||
1ab6c499 DC |
277 | static unsigned long |
278 | nfsd_reply_cache_count(struct shrinker *shrink, struct shrink_control *sc) | |
b4e7f2c9 | 279 | { |
1ab6c499 | 280 | unsigned long num; |
b4e7f2c9 JL |
281 | |
282 | spin_lock(&cache_lock); | |
b4e7f2c9 JL |
283 | num = num_drc_entries; |
284 | spin_unlock(&cache_lock); | |
285 | ||
286 | return num; | |
287 | } | |
288 | ||
1ab6c499 DC |
289 | static unsigned long |
290 | nfsd_reply_cache_scan(struct shrinker *shrink, struct shrink_control *sc) | |
291 | { | |
292 | unsigned long freed; | |
293 | ||
294 | spin_lock(&cache_lock); | |
295 | freed = prune_cache_entries(); | |
296 | spin_unlock(&cache_lock); | |
297 | return freed; | |
298 | } | |
01a7decf JL |
299 | /* |
300 | * Walk an xdr_buf and get a CRC for at most the first RC_CSUMLEN bytes | |
301 | */ | |
302 | static __wsum | |
303 | nfsd_cache_csum(struct svc_rqst *rqstp) | |
304 | { | |
305 | int idx; | |
306 | unsigned int base; | |
307 | __wsum csum; | |
308 | struct xdr_buf *buf = &rqstp->rq_arg; | |
309 | const unsigned char *p = buf->head[0].iov_base; | |
310 | size_t csum_len = min_t(size_t, buf->head[0].iov_len + buf->page_len, | |
311 | RC_CSUMLEN); | |
312 | size_t len = min(buf->head[0].iov_len, csum_len); | |
313 | ||
314 | /* rq_arg.head first */ | |
315 | csum = csum_partial(p, len, 0); | |
316 | csum_len -= len; | |
317 | ||
318 | /* Continue into page array */ | |
319 | idx = buf->page_base / PAGE_SIZE; | |
320 | base = buf->page_base & ~PAGE_MASK; | |
321 | while (csum_len) { | |
322 | p = page_address(buf->pages[idx]) + base; | |
56edc86b | 323 | len = min_t(size_t, PAGE_SIZE - base, csum_len); |
01a7decf JL |
324 | csum = csum_partial(p, len, csum); |
325 | csum_len -= len; | |
326 | base = 0; | |
327 | ++idx; | |
328 | } | |
329 | return csum; | |
330 | } | |
331 | ||
9dc56143 JL |
332 | static bool |
333 | nfsd_cache_match(struct svc_rqst *rqstp, __wsum csum, struct svc_cacherep *rp) | |
334 | { | |
335 | /* Check RPC header info first */ | |
336 | if (rqstp->rq_xid != rp->c_xid || rqstp->rq_proc != rp->c_proc || | |
337 | rqstp->rq_prot != rp->c_prot || rqstp->rq_vers != rp->c_vers || | |
338 | rqstp->rq_arg.len != rp->c_len || | |
339 | !rpc_cmp_addr(svc_addr(rqstp), (struct sockaddr *)&rp->c_addr) || | |
340 | rpc_get_port(svc_addr(rqstp)) != rpc_get_port((struct sockaddr *)&rp->c_addr)) | |
341 | return false; | |
342 | ||
343 | /* compare checksum of NFS data */ | |
344 | if (csum != rp->c_csum) { | |
345 | ++payload_misses; | |
346 | return false; | |
347 | } | |
348 | ||
349 | return true; | |
350 | } | |
351 | ||
a4a3ec32 JL |
352 | /* |
353 | * Search the request hash for an entry that matches the given rqstp. | |
354 | * Must be called with cache_lock held. Returns the found entry or | |
355 | * NULL on failure. | |
356 | */ | |
357 | static struct svc_cacherep * | |
01a7decf | 358 | nfsd_cache_search(struct svc_rqst *rqstp, __wsum csum) |
a4a3ec32 | 359 | { |
98d821bd | 360 | struct svc_cacherep *rp, *ret = NULL; |
a4a3ec32 | 361 | struct hlist_head *rh; |
98d821bd | 362 | unsigned int entries = 0; |
a4a3ec32 | 363 | |
b3d8d128 JL |
364 | /* |
365 | * No point in byte swapping rq_xid since we're just using it to pick | |
366 | * a hash bucket. | |
367 | */ | |
368 | rh = &cache_hash[hash_32((__force u32)rqstp->rq_xid, maskbits)]; | |
b6669737 | 369 | hlist_for_each_entry(rp, rh, c_hash) { |
98d821bd JL |
370 | ++entries; |
371 | if (nfsd_cache_match(rqstp, csum, rp)) { | |
372 | ret = rp; | |
373 | break; | |
374 | } | |
375 | } | |
376 | ||
377 | /* tally hash chain length stats */ | |
378 | if (entries > longest_chain) { | |
379 | longest_chain = entries; | |
380 | longest_chain_cachesize = num_drc_entries; | |
381 | } else if (entries == longest_chain) { | |
382 | /* prefer to keep the smallest cachesize possible here */ | |
383 | longest_chain_cachesize = min(longest_chain_cachesize, | |
384 | num_drc_entries); | |
a4a3ec32 | 385 | } |
98d821bd JL |
386 | |
387 | return ret; | |
a4a3ec32 JL |
388 | } |
389 | ||
1da177e4 LT |
390 | /* |
391 | * Try to find an entry matching the current call in the cache. When none | |
1ac83629 JL |
392 | * is found, we try to grab the oldest expired entry off the LRU list. If |
393 | * a suitable one isn't there, then drop the cache_lock and allocate a | |
394 | * new one, then search again in case one got inserted while this thread | |
395 | * didn't hold the lock. | |
1da177e4 LT |
396 | */ |
397 | int | |
1091006c | 398 | nfsd_cache_lookup(struct svc_rqst *rqstp) |
1da177e4 | 399 | { |
0338dd15 | 400 | struct svc_cacherep *rp, *found; |
c7afef1f AV |
401 | __be32 xid = rqstp->rq_xid; |
402 | u32 proto = rqstp->rq_prot, | |
1da177e4 LT |
403 | vers = rqstp->rq_vers, |
404 | proc = rqstp->rq_proc; | |
01a7decf | 405 | __wsum csum; |
1da177e4 | 406 | unsigned long age; |
1091006c | 407 | int type = rqstp->rq_cachetype; |
0b9ea37f | 408 | int rtn = RC_DOIT; |
1da177e4 LT |
409 | |
410 | rqstp->rq_cacherep = NULL; | |
13cc8a78 | 411 | if (type == RC_NOCACHE) { |
1da177e4 | 412 | nfsdstats.rcnocache++; |
0b9ea37f | 413 | return rtn; |
1da177e4 LT |
414 | } |
415 | ||
01a7decf JL |
416 | csum = nfsd_cache_csum(rqstp); |
417 | ||
0b9ea37f JL |
418 | /* |
419 | * Since the common case is a cache miss followed by an insert, | |
a0ef5e19 | 420 | * preallocate an entry. |
0b9ea37f | 421 | */ |
0338dd15 | 422 | rp = nfsd_reply_cache_alloc(); |
0338dd15 | 423 | spin_lock(&cache_lock); |
6c6910cd | 424 | if (likely(rp)) { |
0b9ea37f | 425 | ++num_drc_entries; |
6c6910cd JL |
426 | drc_mem_usage += sizeof(*rp); |
427 | } | |
0338dd15 | 428 | |
a0ef5e19 JL |
429 | /* go ahead and prune the cache */ |
430 | prune_cache_entries(); | |
431 | ||
01a7decf | 432 | found = nfsd_cache_search(rqstp, csum); |
0338dd15 | 433 | if (found) { |
0b9ea37f JL |
434 | if (likely(rp)) |
435 | nfsd_reply_cache_free_locked(rp); | |
0338dd15 JL |
436 | rp = found; |
437 | goto found_entry; | |
1da177e4 LT |
438 | } |
439 | ||
0b9ea37f JL |
440 | if (!rp) { |
441 | dprintk("nfsd: unable to allocate DRC entry!\n"); | |
442 | goto out; | |
443 | } | |
444 | ||
0338dd15 | 445 | nfsdstats.rcmisses++; |
1da177e4 LT |
446 | rqstp->rq_cacherep = rp; |
447 | rp->c_state = RC_INPROG; | |
448 | rp->c_xid = xid; | |
449 | rp->c_proc = proc; | |
7b9e8522 JL |
450 | rpc_copy_addr((struct sockaddr *)&rp->c_addr, svc_addr(rqstp)); |
451 | rpc_set_port((struct sockaddr *)&rp->c_addr, rpc_get_port(svc_addr(rqstp))); | |
1da177e4 LT |
452 | rp->c_prot = proto; |
453 | rp->c_vers = vers; | |
01a7decf JL |
454 | rp->c_len = rqstp->rq_arg.len; |
455 | rp->c_csum = csum; | |
1da177e4 LT |
456 | |
457 | hash_refile(rp); | |
56c2548b | 458 | lru_put_end(rp); |
1da177e4 LT |
459 | |
460 | /* release any buffer */ | |
461 | if (rp->c_type == RC_REPLBUFF) { | |
6c6910cd | 462 | drc_mem_usage -= rp->c_replvec.iov_len; |
1da177e4 LT |
463 | kfree(rp->c_replvec.iov_base); |
464 | rp->c_replvec.iov_base = NULL; | |
465 | } | |
466 | rp->c_type = RC_NOCACHE; | |
467 | out: | |
468 | spin_unlock(&cache_lock); | |
469 | return rtn; | |
470 | ||
471 | found_entry: | |
0338dd15 | 472 | nfsdstats.rchits++; |
1da177e4 LT |
473 | /* We found a matching entry which is either in progress or done. */ |
474 | age = jiffies - rp->c_timestamp; | |
1da177e4 LT |
475 | lru_put_end(rp); |
476 | ||
477 | rtn = RC_DROPIT; | |
478 | /* Request being processed or excessive rexmits */ | |
479 | if (rp->c_state == RC_INPROG || age < RC_DELAY) | |
480 | goto out; | |
481 | ||
482 | /* From the hall of fame of impractical attacks: | |
483 | * Is this a user who tries to snoop on the cache? */ | |
484 | rtn = RC_DOIT; | |
485 | if (!rqstp->rq_secure && rp->c_secure) | |
486 | goto out; | |
487 | ||
488 | /* Compose RPC reply header */ | |
489 | switch (rp->c_type) { | |
490 | case RC_NOCACHE: | |
491 | break; | |
492 | case RC_REPLSTAT: | |
493 | svc_putu32(&rqstp->rq_res.head[0], rp->c_replstat); | |
494 | rtn = RC_REPLY; | |
495 | break; | |
496 | case RC_REPLBUFF: | |
497 | if (!nfsd_cache_append(rqstp, &rp->c_replvec)) | |
498 | goto out; /* should not happen */ | |
499 | rtn = RC_REPLY; | |
500 | break; | |
501 | default: | |
502 | printk(KERN_WARNING "nfsd: bad repcache type %d\n", rp->c_type); | |
0338dd15 | 503 | nfsd_reply_cache_free_locked(rp); |
1da177e4 LT |
504 | } |
505 | ||
506 | goto out; | |
507 | } | |
508 | ||
509 | /* | |
510 | * Update a cache entry. This is called from nfsd_dispatch when | |
511 | * the procedure has been executed and the complete reply is in | |
512 | * rqstp->rq_res. | |
513 | * | |
514 | * We're copying around data here rather than swapping buffers because | |
515 | * the toplevel loop requires max-sized buffers, which would be a waste | |
516 | * of memory for a cache with a max reply size of 100 bytes (diropokres). | |
517 | * | |
518 | * If we should start to use different types of cache entries tailored | |
519 | * specifically for attrstat and fh's, we may save even more space. | |
520 | * | |
521 | * Also note that a cachetype of RC_NOCACHE can legally be passed when | |
522 | * nfsd failed to encode a reply that otherwise would have been cached. | |
523 | * In this case, nfsd_cache_update is called with statp == NULL. | |
524 | */ | |
525 | void | |
c7afef1f | 526 | nfsd_cache_update(struct svc_rqst *rqstp, int cachetype, __be32 *statp) |
1da177e4 | 527 | { |
13cc8a78 | 528 | struct svc_cacherep *rp = rqstp->rq_cacherep; |
1da177e4 LT |
529 | struct kvec *resv = &rqstp->rq_res.head[0], *cachv; |
530 | int len; | |
6c6910cd | 531 | size_t bufsize = 0; |
1da177e4 | 532 | |
13cc8a78 | 533 | if (!rp) |
1da177e4 LT |
534 | return; |
535 | ||
536 | len = resv->iov_len - ((char*)statp - (char*)resv->iov_base); | |
537 | len >>= 2; | |
fca4217c | 538 | |
1da177e4 LT |
539 | /* Don't cache excessive amounts of data and XDR failures */ |
540 | if (!statp || len > (256 >> 2)) { | |
2c6b691c | 541 | nfsd_reply_cache_free(rp); |
1da177e4 LT |
542 | return; |
543 | } | |
544 | ||
545 | switch (cachetype) { | |
546 | case RC_REPLSTAT: | |
547 | if (len != 1) | |
548 | printk("nfsd: RC_REPLSTAT/reply len %d!\n",len); | |
549 | rp->c_replstat = *statp; | |
550 | break; | |
551 | case RC_REPLBUFF: | |
552 | cachv = &rp->c_replvec; | |
6c6910cd JL |
553 | bufsize = len << 2; |
554 | cachv->iov_base = kmalloc(bufsize, GFP_KERNEL); | |
1da177e4 | 555 | if (!cachv->iov_base) { |
2c6b691c | 556 | nfsd_reply_cache_free(rp); |
1da177e4 LT |
557 | return; |
558 | } | |
6c6910cd JL |
559 | cachv->iov_len = bufsize; |
560 | memcpy(cachv->iov_base, statp, bufsize); | |
1da177e4 | 561 | break; |
2c6b691c JL |
562 | case RC_NOCACHE: |
563 | nfsd_reply_cache_free(rp); | |
564 | return; | |
1da177e4 LT |
565 | } |
566 | spin_lock(&cache_lock); | |
6c6910cd | 567 | drc_mem_usage += bufsize; |
1da177e4 LT |
568 | lru_put_end(rp); |
569 | rp->c_secure = rqstp->rq_secure; | |
570 | rp->c_type = cachetype; | |
571 | rp->c_state = RC_DONE; | |
1da177e4 LT |
572 | spin_unlock(&cache_lock); |
573 | return; | |
574 | } | |
575 | ||
576 | /* | |
577 | * Copy cached reply to current reply buffer. Should always fit. | |
578 | * FIXME as reply is in a page, we should just attach the page, and | |
579 | * keep a refcount.... | |
580 | */ | |
581 | static int | |
582 | nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *data) | |
583 | { | |
584 | struct kvec *vec = &rqstp->rq_res.head[0]; | |
585 | ||
586 | if (vec->iov_len + data->iov_len > PAGE_SIZE) { | |
587 | printk(KERN_WARNING "nfsd: cached reply too large (%Zd).\n", | |
588 | data->iov_len); | |
589 | return 0; | |
590 | } | |
591 | memcpy((char*)vec->iov_base + vec->iov_len, data->iov_base, data->iov_len); | |
592 | vec->iov_len += data->iov_len; | |
593 | return 1; | |
594 | } | |
a2f999a3 JL |
595 | |
596 | /* | |
597 | * Note that fields may be added, removed or reordered in the future. Programs | |
598 | * scraping this file for info should test the labels to ensure they're | |
599 | * getting the correct field. | |
600 | */ | |
601 | static int nfsd_reply_cache_stats_show(struct seq_file *m, void *v) | |
602 | { | |
603 | spin_lock(&cache_lock); | |
604 | seq_printf(m, "max entries: %u\n", max_drc_entries); | |
605 | seq_printf(m, "num entries: %u\n", num_drc_entries); | |
0733c7ba | 606 | seq_printf(m, "hash buckets: %u\n", 1 << maskbits); |
a2f999a3 JL |
607 | seq_printf(m, "mem usage: %u\n", drc_mem_usage); |
608 | seq_printf(m, "cache hits: %u\n", nfsdstats.rchits); | |
609 | seq_printf(m, "cache misses: %u\n", nfsdstats.rcmisses); | |
610 | seq_printf(m, "not cached: %u\n", nfsdstats.rcnocache); | |
611 | seq_printf(m, "payload misses: %u\n", payload_misses); | |
98d821bd JL |
612 | seq_printf(m, "longest chain len: %u\n", longest_chain); |
613 | seq_printf(m, "cachesize at longest: %u\n", longest_chain_cachesize); | |
a2f999a3 JL |
614 | spin_unlock(&cache_lock); |
615 | return 0; | |
616 | } | |
617 | ||
618 | int nfsd_reply_cache_stats_open(struct inode *inode, struct file *file) | |
619 | { | |
620 | return single_open(file, nfsd_reply_cache_stats_show, NULL); | |
621 | } |