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 | ||
9a74af21 BH |
11 | #include "nfsd.h" |
12 | #include "cache.h" | |
1da177e4 LT |
13 | |
14 | /* Size of reply cache. Common values are: | |
15 | * 4.3BSD: 128 | |
16 | * 4.4BSD: 256 | |
17 | * Solaris2: 1024 | |
18 | * DEC Unix: 512-4096 | |
19 | */ | |
20 | #define CACHESIZE 1024 | |
21 | #define HASHSIZE 64 | |
1da177e4 | 22 | |
fca4217c | 23 | static struct hlist_head * cache_hash; |
1da177e4 LT |
24 | static struct list_head lru_head; |
25 | static int cache_disabled = 1; | |
26 | ||
fca4217c GB |
27 | /* |
28 | * Calculate the hash index from an XID. | |
29 | */ | |
30 | static inline u32 request_hash(u32 xid) | |
31 | { | |
32 | u32 h = xid; | |
33 | h ^= (xid >> 24); | |
34 | return h & (HASHSIZE-1); | |
35 | } | |
36 | ||
1da177e4 LT |
37 | static int nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *vec); |
38 | ||
fca4217c | 39 | /* |
1da177e4 LT |
40 | * locking for the reply cache: |
41 | * A cache entry is "single use" if c_state == RC_INPROG | |
42 | * Otherwise, it when accessing _prev or _next, the lock must be held. | |
43 | */ | |
44 | static DEFINE_SPINLOCK(cache_lock); | |
45 | ||
d5c3428b | 46 | int nfsd_reply_cache_init(void) |
1da177e4 LT |
47 | { |
48 | struct svc_cacherep *rp; | |
49 | int i; | |
50 | ||
51 | INIT_LIST_HEAD(&lru_head); | |
52 | i = CACHESIZE; | |
d5c3428b | 53 | while (i) { |
1da177e4 | 54 | rp = kmalloc(sizeof(*rp), GFP_KERNEL); |
d5c3428b BF |
55 | if (!rp) |
56 | goto out_nomem; | |
1da177e4 LT |
57 | list_add(&rp->c_lru, &lru_head); |
58 | rp->c_state = RC_UNUSED; | |
59 | rp->c_type = RC_NOCACHE; | |
60 | INIT_HLIST_NODE(&rp->c_hash); | |
61 | i--; | |
62 | } | |
63 | ||
fca4217c GB |
64 | cache_hash = kcalloc (HASHSIZE, sizeof(struct hlist_head), GFP_KERNEL); |
65 | if (!cache_hash) | |
d5c3428b | 66 | goto out_nomem; |
1da177e4 LT |
67 | |
68 | cache_disabled = 0; | |
d5c3428b BF |
69 | return 0; |
70 | out_nomem: | |
71 | printk(KERN_ERR "nfsd: failed to allocate reply cache\n"); | |
72 | nfsd_reply_cache_shutdown(); | |
73 | return -ENOMEM; | |
1da177e4 LT |
74 | } |
75 | ||
d5c3428b | 76 | void nfsd_reply_cache_shutdown(void) |
1da177e4 LT |
77 | { |
78 | struct svc_cacherep *rp; | |
79 | ||
80 | while (!list_empty(&lru_head)) { | |
81 | rp = list_entry(lru_head.next, struct svc_cacherep, c_lru); | |
82 | if (rp->c_state == RC_DONE && rp->c_type == RC_REPLBUFF) | |
83 | kfree(rp->c_replvec.iov_base); | |
84 | list_del(&rp->c_lru); | |
85 | kfree(rp); | |
86 | } | |
87 | ||
88 | cache_disabled = 1; | |
89 | ||
fca4217c GB |
90 | kfree (cache_hash); |
91 | cache_hash = NULL; | |
1da177e4 LT |
92 | } |
93 | ||
94 | /* | |
95 | * Move cache entry to end of LRU list | |
96 | */ | |
97 | static void | |
98 | lru_put_end(struct svc_cacherep *rp) | |
99 | { | |
f116629d | 100 | list_move_tail(&rp->c_lru, &lru_head); |
1da177e4 LT |
101 | } |
102 | ||
103 | /* | |
104 | * Move a cache entry from one hash list to another | |
105 | */ | |
106 | static void | |
107 | hash_refile(struct svc_cacherep *rp) | |
108 | { | |
109 | hlist_del_init(&rp->c_hash); | |
fca4217c | 110 | hlist_add_head(&rp->c_hash, cache_hash + request_hash(rp->c_xid)); |
1da177e4 LT |
111 | } |
112 | ||
113 | /* | |
114 | * Try to find an entry matching the current call in the cache. When none | |
115 | * is found, we grab the oldest unlocked entry off the LRU list. | |
116 | * Note that no operation within the loop may sleep. | |
117 | */ | |
118 | int | |
119 | nfsd_cache_lookup(struct svc_rqst *rqstp, int type) | |
120 | { | |
121 | struct hlist_node *hn; | |
122 | struct hlist_head *rh; | |
123 | struct svc_cacherep *rp; | |
c7afef1f AV |
124 | __be32 xid = rqstp->rq_xid; |
125 | u32 proto = rqstp->rq_prot, | |
1da177e4 LT |
126 | vers = rqstp->rq_vers, |
127 | proc = rqstp->rq_proc; | |
128 | unsigned long age; | |
129 | int rtn; | |
130 | ||
131 | rqstp->rq_cacherep = NULL; | |
132 | if (cache_disabled || type == RC_NOCACHE) { | |
133 | nfsdstats.rcnocache++; | |
134 | return RC_DOIT; | |
135 | } | |
136 | ||
137 | spin_lock(&cache_lock); | |
138 | rtn = RC_DOIT; | |
139 | ||
fca4217c | 140 | rh = &cache_hash[request_hash(xid)]; |
1da177e4 LT |
141 | hlist_for_each_entry(rp, hn, rh, c_hash) { |
142 | if (rp->c_state != RC_UNUSED && | |
143 | xid == rp->c_xid && proc == rp->c_proc && | |
144 | proto == rp->c_prot && vers == rp->c_vers && | |
145 | time_before(jiffies, rp->c_timestamp + 120*HZ) && | |
146 | memcmp((char*)&rqstp->rq_addr, (char*)&rp->c_addr, sizeof(rp->c_addr))==0) { | |
147 | nfsdstats.rchits++; | |
148 | goto found_entry; | |
149 | } | |
150 | } | |
151 | nfsdstats.rcmisses++; | |
152 | ||
153 | /* This loop shouldn't take more than a few iterations normally */ | |
154 | { | |
155 | int safe = 0; | |
156 | list_for_each_entry(rp, &lru_head, c_lru) { | |
157 | if (rp->c_state != RC_INPROG) | |
158 | break; | |
159 | if (safe++ > CACHESIZE) { | |
160 | printk("nfsd: loop in repcache LRU list\n"); | |
161 | cache_disabled = 1; | |
162 | goto out; | |
163 | } | |
164 | } | |
165 | } | |
166 | ||
cf0a586c GB |
167 | /* All entries on the LRU are in-progress. This should not happen */ |
168 | if (&rp->c_lru == &lru_head) { | |
1da177e4 LT |
169 | static int complaints; |
170 | ||
171 | printk(KERN_WARNING "nfsd: all repcache entries locked!\n"); | |
172 | if (++complaints > 5) { | |
173 | printk(KERN_WARNING "nfsd: disabling repcache.\n"); | |
174 | cache_disabled = 1; | |
175 | } | |
176 | goto out; | |
177 | } | |
178 | ||
179 | rqstp->rq_cacherep = rp; | |
180 | rp->c_state = RC_INPROG; | |
181 | rp->c_xid = xid; | |
182 | rp->c_proc = proc; | |
27459f09 | 183 | memcpy(&rp->c_addr, svc_addr_in(rqstp), sizeof(rp->c_addr)); |
1da177e4 LT |
184 | rp->c_prot = proto; |
185 | rp->c_vers = vers; | |
186 | rp->c_timestamp = jiffies; | |
187 | ||
188 | hash_refile(rp); | |
189 | ||
190 | /* release any buffer */ | |
191 | if (rp->c_type == RC_REPLBUFF) { | |
192 | kfree(rp->c_replvec.iov_base); | |
193 | rp->c_replvec.iov_base = NULL; | |
194 | } | |
195 | rp->c_type = RC_NOCACHE; | |
196 | out: | |
197 | spin_unlock(&cache_lock); | |
198 | return rtn; | |
199 | ||
200 | found_entry: | |
201 | /* We found a matching entry which is either in progress or done. */ | |
202 | age = jiffies - rp->c_timestamp; | |
203 | rp->c_timestamp = jiffies; | |
204 | lru_put_end(rp); | |
205 | ||
206 | rtn = RC_DROPIT; | |
207 | /* Request being processed or excessive rexmits */ | |
208 | if (rp->c_state == RC_INPROG || age < RC_DELAY) | |
209 | goto out; | |
210 | ||
211 | /* From the hall of fame of impractical attacks: | |
212 | * Is this a user who tries to snoop on the cache? */ | |
213 | rtn = RC_DOIT; | |
214 | if (!rqstp->rq_secure && rp->c_secure) | |
215 | goto out; | |
216 | ||
217 | /* Compose RPC reply header */ | |
218 | switch (rp->c_type) { | |
219 | case RC_NOCACHE: | |
220 | break; | |
221 | case RC_REPLSTAT: | |
222 | svc_putu32(&rqstp->rq_res.head[0], rp->c_replstat); | |
223 | rtn = RC_REPLY; | |
224 | break; | |
225 | case RC_REPLBUFF: | |
226 | if (!nfsd_cache_append(rqstp, &rp->c_replvec)) | |
227 | goto out; /* should not happen */ | |
228 | rtn = RC_REPLY; | |
229 | break; | |
230 | default: | |
231 | printk(KERN_WARNING "nfsd: bad repcache type %d\n", rp->c_type); | |
232 | rp->c_state = RC_UNUSED; | |
233 | } | |
234 | ||
235 | goto out; | |
236 | } | |
237 | ||
238 | /* | |
239 | * Update a cache entry. This is called from nfsd_dispatch when | |
240 | * the procedure has been executed and the complete reply is in | |
241 | * rqstp->rq_res. | |
242 | * | |
243 | * We're copying around data here rather than swapping buffers because | |
244 | * the toplevel loop requires max-sized buffers, which would be a waste | |
245 | * of memory for a cache with a max reply size of 100 bytes (diropokres). | |
246 | * | |
247 | * If we should start to use different types of cache entries tailored | |
248 | * specifically for attrstat and fh's, we may save even more space. | |
249 | * | |
250 | * Also note that a cachetype of RC_NOCACHE can legally be passed when | |
251 | * nfsd failed to encode a reply that otherwise would have been cached. | |
252 | * In this case, nfsd_cache_update is called with statp == NULL. | |
253 | */ | |
254 | void | |
c7afef1f | 255 | nfsd_cache_update(struct svc_rqst *rqstp, int cachetype, __be32 *statp) |
1da177e4 LT |
256 | { |
257 | struct svc_cacherep *rp; | |
258 | struct kvec *resv = &rqstp->rq_res.head[0], *cachv; | |
259 | int len; | |
260 | ||
261 | if (!(rp = rqstp->rq_cacherep) || cache_disabled) | |
262 | return; | |
263 | ||
264 | len = resv->iov_len - ((char*)statp - (char*)resv->iov_base); | |
265 | len >>= 2; | |
fca4217c | 266 | |
1da177e4 LT |
267 | /* Don't cache excessive amounts of data and XDR failures */ |
268 | if (!statp || len > (256 >> 2)) { | |
269 | rp->c_state = RC_UNUSED; | |
270 | return; | |
271 | } | |
272 | ||
273 | switch (cachetype) { | |
274 | case RC_REPLSTAT: | |
275 | if (len != 1) | |
276 | printk("nfsd: RC_REPLSTAT/reply len %d!\n",len); | |
277 | rp->c_replstat = *statp; | |
278 | break; | |
279 | case RC_REPLBUFF: | |
280 | cachv = &rp->c_replvec; | |
281 | cachv->iov_base = kmalloc(len << 2, GFP_KERNEL); | |
282 | if (!cachv->iov_base) { | |
283 | spin_lock(&cache_lock); | |
284 | rp->c_state = RC_UNUSED; | |
285 | spin_unlock(&cache_lock); | |
286 | return; | |
287 | } | |
288 | cachv->iov_len = len << 2; | |
289 | memcpy(cachv->iov_base, statp, len << 2); | |
290 | break; | |
291 | } | |
292 | spin_lock(&cache_lock); | |
293 | lru_put_end(rp); | |
294 | rp->c_secure = rqstp->rq_secure; | |
295 | rp->c_type = cachetype; | |
296 | rp->c_state = RC_DONE; | |
297 | rp->c_timestamp = jiffies; | |
298 | spin_unlock(&cache_lock); | |
299 | return; | |
300 | } | |
301 | ||
302 | /* | |
303 | * Copy cached reply to current reply buffer. Should always fit. | |
304 | * FIXME as reply is in a page, we should just attach the page, and | |
305 | * keep a refcount.... | |
306 | */ | |
307 | static int | |
308 | nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *data) | |
309 | { | |
310 | struct kvec *vec = &rqstp->rq_res.head[0]; | |
311 | ||
312 | if (vec->iov_len + data->iov_len > PAGE_SIZE) { | |
313 | printk(KERN_WARNING "nfsd: cached reply too large (%Zd).\n", | |
314 | data->iov_len); | |
315 | return 0; | |
316 | } | |
317 | memcpy((char*)vec->iov_base + vec->iov_len, data->iov_base, data->iov_len); | |
318 | vec->iov_len += data->iov_len; | |
319 | return 1; | |
320 | } |