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Commit | Line | Data |
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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); |
b4e7f2c9 JL |
62 | static int nfsd_reply_cache_shrink(struct shrinker *shrink, |
63 | struct shrink_control *sc); | |
64 | ||
c8c797f9 | 65 | static struct shrinker nfsd_reply_cache_shrinker = { |
b4e7f2c9 JL |
66 | .shrink = nfsd_reply_cache_shrink, |
67 | .seeks = 1, | |
68 | }; | |
1da177e4 | 69 | |
fca4217c | 70 | /* |
1da177e4 LT |
71 | * locking for the reply cache: |
72 | * A cache entry is "single use" if c_state == RC_INPROG | |
73 | * Otherwise, it when accessing _prev or _next, the lock must be held. | |
74 | */ | |
75 | static DEFINE_SPINLOCK(cache_lock); | |
aca8a23d | 76 | static DECLARE_DELAYED_WORK(cache_cleaner, cache_cleaner_func); |
1da177e4 | 77 | |
0338dd15 JL |
78 | /* |
79 | * Put a cap on the size of the DRC based on the amount of available | |
80 | * low memory in the machine. | |
81 | * | |
82 | * 64MB: 8192 | |
83 | * 128MB: 11585 | |
84 | * 256MB: 16384 | |
85 | * 512MB: 23170 | |
86 | * 1GB: 32768 | |
87 | * 2GB: 46340 | |
88 | * 4GB: 65536 | |
89 | * 8GB: 92681 | |
90 | * 16GB: 131072 | |
91 | * | |
92 | * ...with a hard cap of 256k entries. In the worst case, each entry will be | |
93 | * ~1k, so the above numbers should give a rough max of the amount of memory | |
94 | * used in k. | |
95 | */ | |
96 | static unsigned int | |
97 | nfsd_cache_size_limit(void) | |
98 | { | |
99 | unsigned int limit; | |
100 | unsigned long low_pages = totalram_pages - totalhigh_pages; | |
101 | ||
102 | limit = (16 * int_sqrt(low_pages)) << (PAGE_SHIFT-10); | |
103 | return min_t(unsigned int, limit, 256*1024); | |
104 | } | |
105 | ||
0733c7ba JL |
106 | /* |
107 | * Compute the number of hash buckets we need. Divide the max cachesize by | |
108 | * the "target" max bucket size, and round up to next power of two. | |
109 | */ | |
110 | static unsigned int | |
111 | nfsd_hashsize(unsigned int limit) | |
112 | { | |
113 | return roundup_pow_of_two(limit / TARGET_BUCKET_SIZE); | |
114 | } | |
115 | ||
f09841fd JL |
116 | static struct svc_cacherep * |
117 | nfsd_reply_cache_alloc(void) | |
1da177e4 LT |
118 | { |
119 | struct svc_cacherep *rp; | |
1da177e4 | 120 | |
f09841fd JL |
121 | rp = kmem_cache_alloc(drc_slab, GFP_KERNEL); |
122 | if (rp) { | |
1da177e4 LT |
123 | rp->c_state = RC_UNUSED; |
124 | rp->c_type = RC_NOCACHE; | |
f09841fd | 125 | INIT_LIST_HEAD(&rp->c_lru); |
1da177e4 | 126 | INIT_HLIST_NODE(&rp->c_hash); |
1da177e4 | 127 | } |
f09841fd JL |
128 | return rp; |
129 | } | |
1da177e4 | 130 | |
f09841fd JL |
131 | static void |
132 | nfsd_reply_cache_free_locked(struct svc_cacherep *rp) | |
133 | { | |
6c6910cd JL |
134 | if (rp->c_type == RC_REPLBUFF && rp->c_replvec.iov_base) { |
135 | drc_mem_usage -= rp->c_replvec.iov_len; | |
f09841fd | 136 | kfree(rp->c_replvec.iov_base); |
6c6910cd | 137 | } |
a517b608 JL |
138 | if (!hlist_unhashed(&rp->c_hash)) |
139 | hlist_del(&rp->c_hash); | |
f09841fd | 140 | list_del(&rp->c_lru); |
0ee0bf7e | 141 | --num_drc_entries; |
6c6910cd | 142 | drc_mem_usage -= sizeof(*rp); |
f09841fd JL |
143 | kmem_cache_free(drc_slab, rp); |
144 | } | |
145 | ||
2c6b691c JL |
146 | static void |
147 | nfsd_reply_cache_free(struct svc_cacherep *rp) | |
148 | { | |
149 | spin_lock(&cache_lock); | |
150 | nfsd_reply_cache_free_locked(rp); | |
151 | spin_unlock(&cache_lock); | |
152 | } | |
153 | ||
f09841fd JL |
154 | int nfsd_reply_cache_init(void) |
155 | { | |
0733c7ba JL |
156 | unsigned int hashsize; |
157 | ||
ac534ff2 JL |
158 | INIT_LIST_HEAD(&lru_head); |
159 | max_drc_entries = nfsd_cache_size_limit(); | |
160 | num_drc_entries = 0; | |
0733c7ba JL |
161 | hashsize = nfsd_hashsize(max_drc_entries); |
162 | maskbits = ilog2(hashsize); | |
ac534ff2 | 163 | |
b4e7f2c9 | 164 | register_shrinker(&nfsd_reply_cache_shrinker); |
8a8bc40d JL |
165 | drc_slab = kmem_cache_create("nfsd_drc", sizeof(struct svc_cacherep), |
166 | 0, 0, NULL); | |
167 | if (!drc_slab) | |
168 | goto out_nomem; | |
169 | ||
0733c7ba | 170 | cache_hash = kcalloc(hashsize, sizeof(struct hlist_head), GFP_KERNEL); |
fca4217c | 171 | if (!cache_hash) |
d5c3428b | 172 | goto out_nomem; |
1da177e4 | 173 | |
d5c3428b BF |
174 | return 0; |
175 | out_nomem: | |
176 | printk(KERN_ERR "nfsd: failed to allocate reply cache\n"); | |
177 | nfsd_reply_cache_shutdown(); | |
178 | return -ENOMEM; | |
1da177e4 LT |
179 | } |
180 | ||
d5c3428b | 181 | void nfsd_reply_cache_shutdown(void) |
1da177e4 LT |
182 | { |
183 | struct svc_cacherep *rp; | |
184 | ||
b4e7f2c9 | 185 | unregister_shrinker(&nfsd_reply_cache_shrinker); |
aca8a23d JL |
186 | cancel_delayed_work_sync(&cache_cleaner); |
187 | ||
1da177e4 LT |
188 | while (!list_empty(&lru_head)) { |
189 | rp = list_entry(lru_head.next, struct svc_cacherep, c_lru); | |
f09841fd | 190 | nfsd_reply_cache_free_locked(rp); |
1da177e4 LT |
191 | } |
192 | ||
fca4217c GB |
193 | kfree (cache_hash); |
194 | cache_hash = NULL; | |
8a8bc40d JL |
195 | |
196 | if (drc_slab) { | |
197 | kmem_cache_destroy(drc_slab); | |
198 | drc_slab = NULL; | |
199 | } | |
1da177e4 LT |
200 | } |
201 | ||
202 | /* | |
aca8a23d JL |
203 | * Move cache entry to end of LRU list, and queue the cleaner to run if it's |
204 | * not already scheduled. | |
1da177e4 LT |
205 | */ |
206 | static void | |
207 | lru_put_end(struct svc_cacherep *rp) | |
208 | { | |
56c2548b | 209 | rp->c_timestamp = jiffies; |
f116629d | 210 | list_move_tail(&rp->c_lru, &lru_head); |
aca8a23d | 211 | schedule_delayed_work(&cache_cleaner, RC_EXPIRE); |
1da177e4 LT |
212 | } |
213 | ||
214 | /* | |
215 | * Move a cache entry from one hash list to another | |
216 | */ | |
217 | static void | |
218 | hash_refile(struct svc_cacherep *rp) | |
219 | { | |
220 | hlist_del_init(&rp->c_hash); | |
0733c7ba | 221 | hlist_add_head(&rp->c_hash, cache_hash + hash_32(rp->c_xid, maskbits)); |
1da177e4 LT |
222 | } |
223 | ||
d1a0774d JL |
224 | static inline bool |
225 | nfsd_cache_entry_expired(struct svc_cacherep *rp) | |
226 | { | |
227 | return rp->c_state != RC_INPROG && | |
228 | time_after(jiffies, rp->c_timestamp + RC_EXPIRE); | |
229 | } | |
230 | ||
aca8a23d JL |
231 | /* |
232 | * Walk the LRU list and prune off entries that are older than RC_EXPIRE. | |
233 | * Also prune the oldest ones when the total exceeds the max number of entries. | |
234 | */ | |
235 | static void | |
236 | prune_cache_entries(void) | |
237 | { | |
238 | struct svc_cacherep *rp, *tmp; | |
239 | ||
240 | list_for_each_entry_safe(rp, tmp, &lru_head, c_lru) { | |
241 | if (!nfsd_cache_entry_expired(rp) && | |
242 | num_drc_entries <= max_drc_entries) | |
243 | break; | |
244 | nfsd_reply_cache_free_locked(rp); | |
245 | } | |
246 | ||
247 | /* | |
248 | * Conditionally rearm the job. If we cleaned out the list, then | |
249 | * cancel any pending run (since there won't be any work to do). | |
250 | * Otherwise, we rearm the job or modify the existing one to run in | |
251 | * RC_EXPIRE since we just ran the pruner. | |
252 | */ | |
253 | if (list_empty(&lru_head)) | |
254 | cancel_delayed_work(&cache_cleaner); | |
255 | else | |
256 | mod_delayed_work(system_wq, &cache_cleaner, RC_EXPIRE); | |
257 | } | |
258 | ||
259 | static void | |
260 | cache_cleaner_func(struct work_struct *unused) | |
261 | { | |
262 | spin_lock(&cache_lock); | |
263 | prune_cache_entries(); | |
264 | spin_unlock(&cache_lock); | |
265 | } | |
266 | ||
b4e7f2c9 JL |
267 | static int |
268 | nfsd_reply_cache_shrink(struct shrinker *shrink, struct shrink_control *sc) | |
269 | { | |
270 | unsigned int num; | |
271 | ||
272 | spin_lock(&cache_lock); | |
273 | if (sc->nr_to_scan) | |
274 | prune_cache_entries(); | |
275 | num = num_drc_entries; | |
276 | spin_unlock(&cache_lock); | |
277 | ||
278 | return num; | |
279 | } | |
280 | ||
01a7decf JL |
281 | /* |
282 | * Walk an xdr_buf and get a CRC for at most the first RC_CSUMLEN bytes | |
283 | */ | |
284 | static __wsum | |
285 | nfsd_cache_csum(struct svc_rqst *rqstp) | |
286 | { | |
287 | int idx; | |
288 | unsigned int base; | |
289 | __wsum csum; | |
290 | struct xdr_buf *buf = &rqstp->rq_arg; | |
291 | const unsigned char *p = buf->head[0].iov_base; | |
292 | size_t csum_len = min_t(size_t, buf->head[0].iov_len + buf->page_len, | |
293 | RC_CSUMLEN); | |
294 | size_t len = min(buf->head[0].iov_len, csum_len); | |
295 | ||
296 | /* rq_arg.head first */ | |
297 | csum = csum_partial(p, len, 0); | |
298 | csum_len -= len; | |
299 | ||
300 | /* Continue into page array */ | |
301 | idx = buf->page_base / PAGE_SIZE; | |
302 | base = buf->page_base & ~PAGE_MASK; | |
303 | while (csum_len) { | |
304 | p = page_address(buf->pages[idx]) + base; | |
56edc86b | 305 | len = min_t(size_t, PAGE_SIZE - base, csum_len); |
01a7decf JL |
306 | csum = csum_partial(p, len, csum); |
307 | csum_len -= len; | |
308 | base = 0; | |
309 | ++idx; | |
310 | } | |
311 | return csum; | |
312 | } | |
313 | ||
9dc56143 JL |
314 | static bool |
315 | nfsd_cache_match(struct svc_rqst *rqstp, __wsum csum, struct svc_cacherep *rp) | |
316 | { | |
317 | /* Check RPC header info first */ | |
318 | if (rqstp->rq_xid != rp->c_xid || rqstp->rq_proc != rp->c_proc || | |
319 | rqstp->rq_prot != rp->c_prot || rqstp->rq_vers != rp->c_vers || | |
320 | rqstp->rq_arg.len != rp->c_len || | |
321 | !rpc_cmp_addr(svc_addr(rqstp), (struct sockaddr *)&rp->c_addr) || | |
322 | rpc_get_port(svc_addr(rqstp)) != rpc_get_port((struct sockaddr *)&rp->c_addr)) | |
323 | return false; | |
324 | ||
325 | /* compare checksum of NFS data */ | |
326 | if (csum != rp->c_csum) { | |
327 | ++payload_misses; | |
328 | return false; | |
329 | } | |
330 | ||
331 | return true; | |
332 | } | |
333 | ||
a4a3ec32 JL |
334 | /* |
335 | * Search the request hash for an entry that matches the given rqstp. | |
336 | * Must be called with cache_lock held. Returns the found entry or | |
337 | * NULL on failure. | |
338 | */ | |
339 | static struct svc_cacherep * | |
01a7decf | 340 | nfsd_cache_search(struct svc_rqst *rqstp, __wsum csum) |
a4a3ec32 | 341 | { |
98d821bd | 342 | struct svc_cacherep *rp, *ret = NULL; |
a4a3ec32 | 343 | struct hlist_head *rh; |
98d821bd | 344 | unsigned int entries = 0; |
a4a3ec32 | 345 | |
0733c7ba | 346 | rh = &cache_hash[hash_32(rqstp->rq_xid, maskbits)]; |
b6669737 | 347 | hlist_for_each_entry(rp, rh, c_hash) { |
98d821bd JL |
348 | ++entries; |
349 | if (nfsd_cache_match(rqstp, csum, rp)) { | |
350 | ret = rp; | |
351 | break; | |
352 | } | |
353 | } | |
354 | ||
355 | /* tally hash chain length stats */ | |
356 | if (entries > longest_chain) { | |
357 | longest_chain = entries; | |
358 | longest_chain_cachesize = num_drc_entries; | |
359 | } else if (entries == longest_chain) { | |
360 | /* prefer to keep the smallest cachesize possible here */ | |
361 | longest_chain_cachesize = min(longest_chain_cachesize, | |
362 | num_drc_entries); | |
a4a3ec32 | 363 | } |
98d821bd JL |
364 | |
365 | return ret; | |
a4a3ec32 JL |
366 | } |
367 | ||
1da177e4 LT |
368 | /* |
369 | * Try to find an entry matching the current call in the cache. When none | |
1ac83629 JL |
370 | * is found, we try to grab the oldest expired entry off the LRU list. If |
371 | * a suitable one isn't there, then drop the cache_lock and allocate a | |
372 | * new one, then search again in case one got inserted while this thread | |
373 | * didn't hold the lock. | |
1da177e4 LT |
374 | */ |
375 | int | |
1091006c | 376 | nfsd_cache_lookup(struct svc_rqst *rqstp) |
1da177e4 | 377 | { |
0338dd15 | 378 | struct svc_cacherep *rp, *found; |
c7afef1f AV |
379 | __be32 xid = rqstp->rq_xid; |
380 | u32 proto = rqstp->rq_prot, | |
1da177e4 LT |
381 | vers = rqstp->rq_vers, |
382 | proc = rqstp->rq_proc; | |
01a7decf | 383 | __wsum csum; |
1da177e4 | 384 | unsigned long age; |
1091006c | 385 | int type = rqstp->rq_cachetype; |
0b9ea37f | 386 | int rtn = RC_DOIT; |
1da177e4 LT |
387 | |
388 | rqstp->rq_cacherep = NULL; | |
13cc8a78 | 389 | if (type == RC_NOCACHE) { |
1da177e4 | 390 | nfsdstats.rcnocache++; |
0b9ea37f | 391 | return rtn; |
1da177e4 LT |
392 | } |
393 | ||
01a7decf JL |
394 | csum = nfsd_cache_csum(rqstp); |
395 | ||
0b9ea37f JL |
396 | /* |
397 | * Since the common case is a cache miss followed by an insert, | |
398 | * preallocate an entry. First, try to reuse the first entry on the LRU | |
399 | * if it works, then go ahead and prune the LRU list. | |
400 | */ | |
1da177e4 | 401 | spin_lock(&cache_lock); |
0338dd15 JL |
402 | if (!list_empty(&lru_head)) { |
403 | rp = list_first_entry(&lru_head, struct svc_cacherep, c_lru); | |
404 | if (nfsd_cache_entry_expired(rp) || | |
aca8a23d JL |
405 | num_drc_entries >= max_drc_entries) { |
406 | lru_put_end(rp); | |
407 | prune_cache_entries(); | |
0b9ea37f | 408 | goto search_cache; |
1da177e4 LT |
409 | } |
410 | } | |
1da177e4 | 411 | |
0b9ea37f | 412 | /* No expired ones available, allocate a new one. */ |
0338dd15 JL |
413 | spin_unlock(&cache_lock); |
414 | rp = nfsd_reply_cache_alloc(); | |
0338dd15 | 415 | spin_lock(&cache_lock); |
6c6910cd | 416 | if (likely(rp)) { |
0b9ea37f | 417 | ++num_drc_entries; |
6c6910cd JL |
418 | drc_mem_usage += sizeof(*rp); |
419 | } | |
0338dd15 | 420 | |
0b9ea37f | 421 | search_cache: |
01a7decf | 422 | found = nfsd_cache_search(rqstp, csum); |
0338dd15 | 423 | if (found) { |
0b9ea37f JL |
424 | if (likely(rp)) |
425 | nfsd_reply_cache_free_locked(rp); | |
0338dd15 JL |
426 | rp = found; |
427 | goto found_entry; | |
1da177e4 LT |
428 | } |
429 | ||
0b9ea37f JL |
430 | if (!rp) { |
431 | dprintk("nfsd: unable to allocate DRC entry!\n"); | |
432 | goto out; | |
433 | } | |
434 | ||
0338dd15 JL |
435 | /* |
436 | * We're keeping the one we just allocated. Are we now over the | |
437 | * limit? Prune one off the tip of the LRU in trade for the one we | |
438 | * just allocated if so. | |
439 | */ | |
440 | if (num_drc_entries >= max_drc_entries) | |
441 | nfsd_reply_cache_free_locked(list_first_entry(&lru_head, | |
442 | struct svc_cacherep, c_lru)); | |
1da177e4 | 443 | |
0338dd15 | 444 | nfsdstats.rcmisses++; |
1da177e4 LT |
445 | rqstp->rq_cacherep = rp; |
446 | rp->c_state = RC_INPROG; | |
447 | rp->c_xid = xid; | |
448 | rp->c_proc = proc; | |
7b9e8522 JL |
449 | rpc_copy_addr((struct sockaddr *)&rp->c_addr, svc_addr(rqstp)); |
450 | rpc_set_port((struct sockaddr *)&rp->c_addr, rpc_get_port(svc_addr(rqstp))); | |
1da177e4 LT |
451 | rp->c_prot = proto; |
452 | rp->c_vers = vers; | |
01a7decf JL |
453 | rp->c_len = rqstp->rq_arg.len; |
454 | rp->c_csum = csum; | |
1da177e4 LT |
455 | |
456 | hash_refile(rp); | |
56c2548b | 457 | lru_put_end(rp); |
1da177e4 LT |
458 | |
459 | /* release any buffer */ | |
460 | if (rp->c_type == RC_REPLBUFF) { | |
6c6910cd | 461 | drc_mem_usage -= rp->c_replvec.iov_len; |
1da177e4 LT |
462 | kfree(rp->c_replvec.iov_base); |
463 | rp->c_replvec.iov_base = NULL; | |
464 | } | |
465 | rp->c_type = RC_NOCACHE; | |
466 | out: | |
467 | spin_unlock(&cache_lock); | |
468 | return rtn; | |
469 | ||
470 | found_entry: | |
0338dd15 | 471 | nfsdstats.rchits++; |
1da177e4 LT |
472 | /* We found a matching entry which is either in progress or done. */ |
473 | age = jiffies - rp->c_timestamp; | |
1da177e4 LT |
474 | lru_put_end(rp); |
475 | ||
476 | rtn = RC_DROPIT; | |
477 | /* Request being processed or excessive rexmits */ | |
478 | if (rp->c_state == RC_INPROG || age < RC_DELAY) | |
479 | goto out; | |
480 | ||
481 | /* From the hall of fame of impractical attacks: | |
482 | * Is this a user who tries to snoop on the cache? */ | |
483 | rtn = RC_DOIT; | |
484 | if (!rqstp->rq_secure && rp->c_secure) | |
485 | goto out; | |
486 | ||
487 | /* Compose RPC reply header */ | |
488 | switch (rp->c_type) { | |
489 | case RC_NOCACHE: | |
490 | break; | |
491 | case RC_REPLSTAT: | |
492 | svc_putu32(&rqstp->rq_res.head[0], rp->c_replstat); | |
493 | rtn = RC_REPLY; | |
494 | break; | |
495 | case RC_REPLBUFF: | |
496 | if (!nfsd_cache_append(rqstp, &rp->c_replvec)) | |
497 | goto out; /* should not happen */ | |
498 | rtn = RC_REPLY; | |
499 | break; | |
500 | default: | |
501 | printk(KERN_WARNING "nfsd: bad repcache type %d\n", rp->c_type); | |
0338dd15 | 502 | nfsd_reply_cache_free_locked(rp); |
1da177e4 LT |
503 | } |
504 | ||
505 | goto out; | |
506 | } | |
507 | ||
508 | /* | |
509 | * Update a cache entry. This is called from nfsd_dispatch when | |
510 | * the procedure has been executed and the complete reply is in | |
511 | * rqstp->rq_res. | |
512 | * | |
513 | * We're copying around data here rather than swapping buffers because | |
514 | * the toplevel loop requires max-sized buffers, which would be a waste | |
515 | * of memory for a cache with a max reply size of 100 bytes (diropokres). | |
516 | * | |
517 | * If we should start to use different types of cache entries tailored | |
518 | * specifically for attrstat and fh's, we may save even more space. | |
519 | * | |
520 | * Also note that a cachetype of RC_NOCACHE can legally be passed when | |
521 | * nfsd failed to encode a reply that otherwise would have been cached. | |
522 | * In this case, nfsd_cache_update is called with statp == NULL. | |
523 | */ | |
524 | void | |
c7afef1f | 525 | nfsd_cache_update(struct svc_rqst *rqstp, int cachetype, __be32 *statp) |
1da177e4 | 526 | { |
13cc8a78 | 527 | struct svc_cacherep *rp = rqstp->rq_cacherep; |
1da177e4 LT |
528 | struct kvec *resv = &rqstp->rq_res.head[0], *cachv; |
529 | int len; | |
6c6910cd | 530 | size_t bufsize = 0; |
1da177e4 | 531 | |
13cc8a78 | 532 | if (!rp) |
1da177e4 LT |
533 | return; |
534 | ||
535 | len = resv->iov_len - ((char*)statp - (char*)resv->iov_base); | |
536 | len >>= 2; | |
fca4217c | 537 | |
1da177e4 LT |
538 | /* Don't cache excessive amounts of data and XDR failures */ |
539 | if (!statp || len > (256 >> 2)) { | |
2c6b691c | 540 | nfsd_reply_cache_free(rp); |
1da177e4 LT |
541 | return; |
542 | } | |
543 | ||
544 | switch (cachetype) { | |
545 | case RC_REPLSTAT: | |
546 | if (len != 1) | |
547 | printk("nfsd: RC_REPLSTAT/reply len %d!\n",len); | |
548 | rp->c_replstat = *statp; | |
549 | break; | |
550 | case RC_REPLBUFF: | |
551 | cachv = &rp->c_replvec; | |
6c6910cd JL |
552 | bufsize = len << 2; |
553 | cachv->iov_base = kmalloc(bufsize, GFP_KERNEL); | |
1da177e4 | 554 | if (!cachv->iov_base) { |
2c6b691c | 555 | nfsd_reply_cache_free(rp); |
1da177e4 LT |
556 | return; |
557 | } | |
6c6910cd JL |
558 | cachv->iov_len = bufsize; |
559 | memcpy(cachv->iov_base, statp, bufsize); | |
1da177e4 | 560 | break; |
2c6b691c JL |
561 | case RC_NOCACHE: |
562 | nfsd_reply_cache_free(rp); | |
563 | return; | |
1da177e4 LT |
564 | } |
565 | spin_lock(&cache_lock); | |
6c6910cd | 566 | drc_mem_usage += bufsize; |
1da177e4 LT |
567 | lru_put_end(rp); |
568 | rp->c_secure = rqstp->rq_secure; | |
569 | rp->c_type = cachetype; | |
570 | rp->c_state = RC_DONE; | |
1da177e4 LT |
571 | spin_unlock(&cache_lock); |
572 | return; | |
573 | } | |
574 | ||
575 | /* | |
576 | * Copy cached reply to current reply buffer. Should always fit. | |
577 | * FIXME as reply is in a page, we should just attach the page, and | |
578 | * keep a refcount.... | |
579 | */ | |
580 | static int | |
581 | nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *data) | |
582 | { | |
583 | struct kvec *vec = &rqstp->rq_res.head[0]; | |
584 | ||
585 | if (vec->iov_len + data->iov_len > PAGE_SIZE) { | |
586 | printk(KERN_WARNING "nfsd: cached reply too large (%Zd).\n", | |
587 | data->iov_len); | |
588 | return 0; | |
589 | } | |
590 | memcpy((char*)vec->iov_base + vec->iov_len, data->iov_base, data->iov_len); | |
591 | vec->iov_len += data->iov_len; | |
592 | return 1; | |
593 | } | |
a2f999a3 JL |
594 | |
595 | /* | |
596 | * Note that fields may be added, removed or reordered in the future. Programs | |
597 | * scraping this file for info should test the labels to ensure they're | |
598 | * getting the correct field. | |
599 | */ | |
600 | static int nfsd_reply_cache_stats_show(struct seq_file *m, void *v) | |
601 | { | |
602 | spin_lock(&cache_lock); | |
603 | seq_printf(m, "max entries: %u\n", max_drc_entries); | |
604 | seq_printf(m, "num entries: %u\n", num_drc_entries); | |
0733c7ba | 605 | seq_printf(m, "hash buckets: %u\n", 1 << maskbits); |
a2f999a3 JL |
606 | seq_printf(m, "mem usage: %u\n", drc_mem_usage); |
607 | seq_printf(m, "cache hits: %u\n", nfsdstats.rchits); | |
608 | seq_printf(m, "cache misses: %u\n", nfsdstats.rcmisses); | |
609 | seq_printf(m, "not cached: %u\n", nfsdstats.rcnocache); | |
610 | seq_printf(m, "payload misses: %u\n", payload_misses); | |
98d821bd JL |
611 | seq_printf(m, "longest chain len: %u\n", longest_chain); |
612 | seq_printf(m, "cachesize at longest: %u\n", longest_chain_cachesize); | |
a2f999a3 JL |
613 | spin_unlock(&cache_lock); |
614 | return 0; | |
615 | } | |
616 | ||
617 | int nfsd_reply_cache_stats_open(struct inode *inode, struct file *file) | |
618 | { | |
619 | return single_open(file, nfsd_reply_cache_stats_show, NULL); | |
620 | } |