xref: /linux/fs/lockd/host.c (revision f3d9478b2ce468c3115b02ecae7e975990697f15) 
1 /*
2  * linux/fs/lockd/host.c
3  *
4  * Management for NLM peer hosts. The nlm_host struct is shared
5  * between client and server implementation. The only reason to
6  * do so is to reduce code bloat.
7  *
8  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
9  */
10 
11 #include <linux/types.h>
12 #include <linux/sched.h>
13 #include <linux/slab.h>
14 #include <linux/in.h>
15 #include <linux/sunrpc/clnt.h>
16 #include <linux/sunrpc/svc.h>
17 #include <linux/lockd/lockd.h>
18 #include <linux/lockd/sm_inter.h>
19 #include <linux/mutex.h>
20 
21 
22 #define NLMDBG_FACILITY		NLMDBG_HOSTCACHE
23 #define NLM_HOST_MAX		64
24 #define NLM_HOST_NRHASH		32
25 #define NLM_ADDRHASH(addr)	(ntohl(addr) & (NLM_HOST_NRHASH-1))
26 #define NLM_HOST_REBIND		(60 * HZ)
27 #define NLM_HOST_EXPIRE		((nrhosts > NLM_HOST_MAX)? 300 * HZ : 120 * HZ)
28 #define NLM_HOST_COLLECT	((nrhosts > NLM_HOST_MAX)? 120 * HZ :  60 * HZ)
29 #define NLM_HOST_ADDR(sv)	(&(sv)->s_nlmclnt->cl_xprt->addr)
30 
31 static struct nlm_host *	nlm_hosts[NLM_HOST_NRHASH];
32 static unsigned long		next_gc;
33 static int			nrhosts;
34 static DEFINE_MUTEX(nlm_host_mutex);
35 
36 
37 static void			nlm_gc_hosts(void);
38 
39 /*
40  * Find an NLM server handle in the cache. If there is none, create it.
41  */
42 struct nlm_host *
43 nlmclnt_lookup_host(struct sockaddr_in *sin, int proto, int version)
44 {
45 	return nlm_lookup_host(0, sin, proto, version);
46 }
47 
48 /*
49  * Find an NLM client handle in the cache. If there is none, create it.
50  */
51 struct nlm_host *
52 nlmsvc_lookup_host(struct svc_rqst *rqstp)
53 {
54 	return nlm_lookup_host(1, &rqstp->rq_addr,
55 			       rqstp->rq_prot, rqstp->rq_vers);
56 }
57 
58 /*
59  * Common host lookup routine for server & client
60  */
61 struct nlm_host *
62 nlm_lookup_host(int server, struct sockaddr_in *sin,
63 					int proto, int version)
64 {
65 	struct nlm_host	*host, **hp;
66 	u32		addr;
67 	int		hash;
68 
69 	dprintk("lockd: nlm_lookup_host(%08x, p=%d, v=%d)\n",
70 			(unsigned)(sin? ntohl(sin->sin_addr.s_addr) : 0), proto, version);
71 
72 	hash = NLM_ADDRHASH(sin->sin_addr.s_addr);
73 
74 	/* Lock hash table */
75 	mutex_lock(&nlm_host_mutex);
76 
77 	if (time_after_eq(jiffies, next_gc))
78 		nlm_gc_hosts();
79 
80 	for (hp = &nlm_hosts[hash]; (host = *hp) != 0; hp = &host->h_next) {
81 		if (host->h_proto != proto)
82 			continue;
83 		if (host->h_version != version)
84 			continue;
85 		if (host->h_server != server)
86 			continue;
87 
88 		if (nlm_cmp_addr(&host->h_addr, sin)) {
89 			if (hp != nlm_hosts + hash) {
90 				*hp = host->h_next;
91 				host->h_next = nlm_hosts[hash];
92 				nlm_hosts[hash] = host;
93 			}
94 			nlm_get_host(host);
95 			mutex_unlock(&nlm_host_mutex);
96 			return host;
97 		}
98 	}
99 
100 	/* Ooops, no host found, create it */
101 	dprintk("lockd: creating host entry\n");
102 
103 	if (!(host = (struct nlm_host *) kmalloc(sizeof(*host), GFP_KERNEL)))
104 		goto nohost;
105 	memset(host, 0, sizeof(*host));
106 
107 	addr = sin->sin_addr.s_addr;
108 	sprintf(host->h_name, "%u.%u.%u.%u", NIPQUAD(addr));
109 
110 	host->h_addr       = *sin;
111 	host->h_addr.sin_port = 0;	/* ouch! */
112 	host->h_version    = version;
113 	host->h_proto      = proto;
114 	host->h_rpcclnt    = NULL;
115 	init_MUTEX(&host->h_sema);
116 	host->h_nextrebind = jiffies + NLM_HOST_REBIND;
117 	host->h_expires    = jiffies + NLM_HOST_EXPIRE;
118 	atomic_set(&host->h_count, 1);
119 	init_waitqueue_head(&host->h_gracewait);
120 	host->h_state      = 0;			/* pseudo NSM state */
121 	host->h_nsmstate   = 0;			/* real NSM state */
122 	host->h_server	   = server;
123 	host->h_next       = nlm_hosts[hash];
124 	nlm_hosts[hash]    = host;
125 	INIT_LIST_HEAD(&host->h_lockowners);
126 	spin_lock_init(&host->h_lock);
127 	INIT_LIST_HEAD(&host->h_granted);
128 	INIT_LIST_HEAD(&host->h_reclaim);
129 
130 	if (++nrhosts > NLM_HOST_MAX)
131 		next_gc = 0;
132 
133 nohost:
134 	mutex_unlock(&nlm_host_mutex);
135 	return host;
136 }
137 
138 struct nlm_host *
139 nlm_find_client(void)
140 {
141 	/* find a nlm_host for a client for which h_killed == 0.
142 	 * and return it
143 	 */
144 	int hash;
145 	mutex_lock(&nlm_host_mutex);
146 	for (hash = 0 ; hash < NLM_HOST_NRHASH; hash++) {
147 		struct nlm_host *host, **hp;
148 		for (hp = &nlm_hosts[hash]; (host = *hp) != 0; hp = &host->h_next) {
149 			if (host->h_server &&
150 			    host->h_killed == 0) {
151 				nlm_get_host(host);
152 				mutex_unlock(&nlm_host_mutex);
153 				return host;
154 			}
155 		}
156 	}
157 	mutex_unlock(&nlm_host_mutex);
158 	return NULL;
159 }
160 
161 
162 /*
163  * Create the NLM RPC client for an NLM peer
164  */
165 struct rpc_clnt *
166 nlm_bind_host(struct nlm_host *host)
167 {
168 	struct rpc_clnt	*clnt;
169 	struct rpc_xprt	*xprt;
170 
171 	dprintk("lockd: nlm_bind_host(%08x)\n",
172 			(unsigned)ntohl(host->h_addr.sin_addr.s_addr));
173 
174 	/* Lock host handle */
175 	down(&host->h_sema);
176 
177 	/* If we've already created an RPC client, check whether
178 	 * RPC rebind is required
179 	 */
180 	if ((clnt = host->h_rpcclnt) != NULL) {
181 		xprt = clnt->cl_xprt;
182 		if (time_after_eq(jiffies, host->h_nextrebind)) {
183 			rpc_force_rebind(clnt);
184 			host->h_nextrebind = jiffies + NLM_HOST_REBIND;
185 			dprintk("lockd: next rebind in %ld jiffies\n",
186 					host->h_nextrebind - jiffies);
187 		}
188 	} else {
189 		xprt = xprt_create_proto(host->h_proto, &host->h_addr, NULL);
190 		if (IS_ERR(xprt))
191 			goto forgetit;
192 
193 		xprt_set_timeout(&xprt->timeout, 5, nlmsvc_timeout);
194 		xprt->resvport = 1;	/* NLM requires a reserved port */
195 
196 		/* Existing NLM servers accept AUTH_UNIX only */
197 		clnt = rpc_new_client(xprt, host->h_name, &nlm_program,
198 					host->h_version, RPC_AUTH_UNIX);
199 		if (IS_ERR(clnt))
200 			goto forgetit;
201 		clnt->cl_autobind = 1;	/* turn on pmap queries */
202 		clnt->cl_softrtry = 1; /* All queries are soft */
203 
204 		host->h_rpcclnt = clnt;
205 	}
206 
207 	up(&host->h_sema);
208 	return clnt;
209 
210 forgetit:
211 	printk("lockd: couldn't create RPC handle for %s\n", host->h_name);
212 	up(&host->h_sema);
213 	return NULL;
214 }
215 
216 /*
217  * Force a portmap lookup of the remote lockd port
218  */
219 void
220 nlm_rebind_host(struct nlm_host *host)
221 {
222 	dprintk("lockd: rebind host %s\n", host->h_name);
223 	if (host->h_rpcclnt && time_after_eq(jiffies, host->h_nextrebind)) {
224 		rpc_force_rebind(host->h_rpcclnt);
225 		host->h_nextrebind = jiffies + NLM_HOST_REBIND;
226 	}
227 }
228 
229 /*
230  * Increment NLM host count
231  */
232 struct nlm_host * nlm_get_host(struct nlm_host *host)
233 {
234 	if (host) {
235 		dprintk("lockd: get host %s\n", host->h_name);
236 		atomic_inc(&host->h_count);
237 		host->h_expires = jiffies + NLM_HOST_EXPIRE;
238 	}
239 	return host;
240 }
241 
242 /*
243  * Release NLM host after use
244  */
245 void nlm_release_host(struct nlm_host *host)
246 {
247 	if (host != NULL) {
248 		dprintk("lockd: release host %s\n", host->h_name);
249 		BUG_ON(atomic_read(&host->h_count) < 0);
250 		if (atomic_dec_and_test(&host->h_count)) {
251 			BUG_ON(!list_empty(&host->h_lockowners));
252 			BUG_ON(!list_empty(&host->h_granted));
253 			BUG_ON(!list_empty(&host->h_reclaim));
254 		}
255 	}
256 }
257 
258 /*
259  * Shut down the hosts module.
260  * Note that this routine is called only at server shutdown time.
261  */
262 void
263 nlm_shutdown_hosts(void)
264 {
265 	struct nlm_host	*host;
266 	int		i;
267 
268 	dprintk("lockd: shutting down host module\n");
269 	mutex_lock(&nlm_host_mutex);
270 
271 	/* First, make all hosts eligible for gc */
272 	dprintk("lockd: nuking all hosts...\n");
273 	for (i = 0; i < NLM_HOST_NRHASH; i++) {
274 		for (host = nlm_hosts[i]; host; host = host->h_next)
275 			host->h_expires = jiffies - 1;
276 	}
277 
278 	/* Then, perform a garbage collection pass */
279 	nlm_gc_hosts();
280 	mutex_unlock(&nlm_host_mutex);
281 
282 	/* complain if any hosts are left */
283 	if (nrhosts) {
284 		printk(KERN_WARNING "lockd: couldn't shutdown host module!\n");
285 		dprintk("lockd: %d hosts left:\n", nrhosts);
286 		for (i = 0; i < NLM_HOST_NRHASH; i++) {
287 			for (host = nlm_hosts[i]; host; host = host->h_next) {
288 				dprintk("       %s (cnt %d use %d exp %ld)\n",
289 					host->h_name, atomic_read(&host->h_count),
290 					host->h_inuse, host->h_expires);
291 			}
292 		}
293 	}
294 }
295 
296 /*
297  * Garbage collect any unused NLM hosts.
298  * This GC combines reference counting for async operations with
299  * mark & sweep for resources held by remote clients.
300  */
301 static void
302 nlm_gc_hosts(void)
303 {
304 	struct nlm_host	**q, *host;
305 	struct rpc_clnt	*clnt;
306 	int		i;
307 
308 	dprintk("lockd: host garbage collection\n");
309 	for (i = 0; i < NLM_HOST_NRHASH; i++) {
310 		for (host = nlm_hosts[i]; host; host = host->h_next)
311 			host->h_inuse = 0;
312 	}
313 
314 	/* Mark all hosts that hold locks, blocks or shares */
315 	nlmsvc_mark_resources();
316 
317 	for (i = 0; i < NLM_HOST_NRHASH; i++) {
318 		q = &nlm_hosts[i];
319 		while ((host = *q) != NULL) {
320 			if (atomic_read(&host->h_count) || host->h_inuse
321 			 || time_before(jiffies, host->h_expires)) {
322 				dprintk("nlm_gc_hosts skipping %s (cnt %d use %d exp %ld)\n",
323 					host->h_name, atomic_read(&host->h_count),
324 					host->h_inuse, host->h_expires);
325 				q = &host->h_next;
326 				continue;
327 			}
328 			dprintk("lockd: delete host %s\n", host->h_name);
329 			*q = host->h_next;
330 			/* Don't unmonitor hosts that have been invalidated */
331 			if (host->h_monitored && !host->h_killed)
332 				nsm_unmonitor(host);
333 			if ((clnt = host->h_rpcclnt) != NULL) {
334 				if (atomic_read(&clnt->cl_users)) {
335 					printk(KERN_WARNING
336 						"lockd: active RPC handle\n");
337 					clnt->cl_dead = 1;
338 				} else {
339 					rpc_destroy_client(host->h_rpcclnt);
340 				}
341 			}
342 			kfree(host);
343 			nrhosts--;
344 		}
345 	}
346 
347 	next_gc = jiffies + NLM_HOST_COLLECT;
348 }
349 
350