xref: /openbmc/linux/fs/lockd/host.c (revision 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2) 
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 
20 
21 #define NLMDBG_FACILITY		NLMDBG_HOSTCACHE
22 #define NLM_HOST_MAX		64
23 #define NLM_HOST_NRHASH		32
24 #define NLM_ADDRHASH(addr)	(ntohl(addr) & (NLM_HOST_NRHASH-1))
25 #define NLM_HOST_REBIND		(60 * HZ)
26 #define NLM_HOST_EXPIRE		((nrhosts > NLM_HOST_MAX)? 300 * HZ : 120 * HZ)
27 #define NLM_HOST_COLLECT	((nrhosts > NLM_HOST_MAX)? 120 * HZ :  60 * HZ)
28 #define NLM_HOST_ADDR(sv)	(&(sv)->s_nlmclnt->cl_xprt->addr)
29 
30 static struct nlm_host *	nlm_hosts[NLM_HOST_NRHASH];
31 static unsigned long		next_gc;
32 static int			nrhosts;
33 static DECLARE_MUTEX(nlm_host_sema);
34 
35 
36 static void			nlm_gc_hosts(void);
37 
38 /*
39  * Find an NLM server handle in the cache. If there is none, create it.
40  */
41 struct nlm_host *
42 nlmclnt_lookup_host(struct sockaddr_in *sin, int proto, int version)
43 {
44 	return nlm_lookup_host(0, sin, proto, version);
45 }
46 
47 /*
48  * Find an NLM client handle in the cache. If there is none, create it.
49  */
50 struct nlm_host *
51 nlmsvc_lookup_host(struct svc_rqst *rqstp)
52 {
53 	return nlm_lookup_host(1, &rqstp->rq_addr,
54 			       rqstp->rq_prot, rqstp->rq_vers);
55 }
56 
57 /*
58  * Common host lookup routine for server & client
59  */
60 struct nlm_host *
61 nlm_lookup_host(int server, struct sockaddr_in *sin,
62 					int proto, int version)
63 {
64 	struct nlm_host	*host, **hp;
65 	u32		addr;
66 	int		hash;
67 
68 	dprintk("lockd: nlm_lookup_host(%08x, p=%d, v=%d)\n",
69 			(unsigned)(sin? ntohl(sin->sin_addr.s_addr) : 0), proto, version);
70 
71 	hash = NLM_ADDRHASH(sin->sin_addr.s_addr);
72 
73 	/* Lock hash table */
74 	down(&nlm_host_sema);
75 
76 	if (time_after_eq(jiffies, next_gc))
77 		nlm_gc_hosts();
78 
79 	for (hp = &nlm_hosts[hash]; (host = *hp) != 0; hp = &host->h_next) {
80 		if (host->h_proto != proto)
81 			continue;
82 		if (host->h_version != version)
83 			continue;
84 		if (host->h_server != server)
85 			continue;
86 
87 		if (nlm_cmp_addr(&host->h_addr, sin)) {
88 			if (hp != nlm_hosts + hash) {
89 				*hp = host->h_next;
90 				host->h_next = nlm_hosts[hash];
91 				nlm_hosts[hash] = host;
92 			}
93 			nlm_get_host(host);
94 			up(&nlm_host_sema);
95 			return host;
96 		}
97 	}
98 
99 	/* Ooops, no host found, create it */
100 	dprintk("lockd: creating host entry\n");
101 
102 	if (!(host = (struct nlm_host *) kmalloc(sizeof(*host), GFP_KERNEL)))
103 		goto nohost;
104 	memset(host, 0, sizeof(*host));
105 
106 	addr = sin->sin_addr.s_addr;
107 	sprintf(host->h_name, "%u.%u.%u.%u", NIPQUAD(addr));
108 
109 	host->h_addr       = *sin;
110 	host->h_addr.sin_port = 0;	/* ouch! */
111 	host->h_version    = version;
112 	host->h_proto      = proto;
113 	host->h_rpcclnt    = NULL;
114 	init_MUTEX(&host->h_sema);
115 	host->h_nextrebind = jiffies + NLM_HOST_REBIND;
116 	host->h_expires    = jiffies + NLM_HOST_EXPIRE;
117 	atomic_set(&host->h_count, 1);
118 	init_waitqueue_head(&host->h_gracewait);
119 	host->h_state      = 0;			/* pseudo NSM state */
120 	host->h_nsmstate   = 0;			/* real NSM state */
121 	host->h_server	   = server;
122 	host->h_next       = nlm_hosts[hash];
123 	nlm_hosts[hash]    = host;
124 	INIT_LIST_HEAD(&host->h_lockowners);
125 	spin_lock_init(&host->h_lock);
126 
127 	if (++nrhosts > NLM_HOST_MAX)
128 		next_gc = 0;
129 
130 nohost:
131 	up(&nlm_host_sema);
132 	return host;
133 }
134 
135 struct nlm_host *
136 nlm_find_client(void)
137 {
138 	/* find a nlm_host for a client for which h_killed == 0.
139 	 * and return it
140 	 */
141 	int hash;
142 	down(&nlm_host_sema);
143 	for (hash = 0 ; hash < NLM_HOST_NRHASH; hash++) {
144 		struct nlm_host *host, **hp;
145 		for (hp = &nlm_hosts[hash]; (host = *hp) != 0; hp = &host->h_next) {
146 			if (host->h_server &&
147 			    host->h_killed == 0) {
148 				nlm_get_host(host);
149 				up(&nlm_host_sema);
150 				return host;
151 			}
152 		}
153 	}
154 	up(&nlm_host_sema);
155 	return NULL;
156 }
157 
158 
159 /*
160  * Create the NLM RPC client for an NLM peer
161  */
162 struct rpc_clnt *
163 nlm_bind_host(struct nlm_host *host)
164 {
165 	struct rpc_clnt	*clnt;
166 	struct rpc_xprt	*xprt;
167 
168 	dprintk("lockd: nlm_bind_host(%08x)\n",
169 			(unsigned)ntohl(host->h_addr.sin_addr.s_addr));
170 
171 	/* Lock host handle */
172 	down(&host->h_sema);
173 
174 	/* If we've already created an RPC client, check whether
175 	 * RPC rebind is required
176 	 * Note: why keep rebinding if we're on a tcp connection?
177 	 */
178 	if ((clnt = host->h_rpcclnt) != NULL) {
179 		xprt = clnt->cl_xprt;
180 		if (!xprt->stream && time_after_eq(jiffies, host->h_nextrebind)) {
181 			clnt->cl_port = 0;
182 			host->h_nextrebind = jiffies + NLM_HOST_REBIND;
183 			dprintk("lockd: next rebind in %ld jiffies\n",
184 					host->h_nextrebind - jiffies);
185 		}
186 	} else {
187 		xprt = xprt_create_proto(host->h_proto, &host->h_addr, NULL);
188 		if (IS_ERR(xprt))
189 			goto forgetit;
190 
191 		xprt_set_timeout(&xprt->timeout, 5, nlmsvc_timeout);
192 
193 		/* Existing NLM servers accept AUTH_UNIX only */
194 		clnt = rpc_create_client(xprt, host->h_name, &nlm_program,
195 					host->h_version, RPC_AUTH_UNIX);
196 		if (IS_ERR(clnt)) {
197 			xprt_destroy(xprt);
198 			goto forgetit;
199 		}
200 		clnt->cl_autobind = 1;	/* turn on pmap queries */
201 		xprt->nocong = 1;	/* No congestion control for NLM */
202 		xprt->resvport = 1;	/* NLM requires a reserved port */
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 		host->h_rpcclnt->cl_port = 0;
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 		atomic_dec(&host->h_count);
250 		BUG_ON(atomic_read(&host->h_count) < 0);
251 	}
252 }
253 
254 /*
255  * Shut down the hosts module.
256  * Note that this routine is called only at server shutdown time.
257  */
258 void
259 nlm_shutdown_hosts(void)
260 {
261 	struct nlm_host	*host;
262 	int		i;
263 
264 	dprintk("lockd: shutting down host module\n");
265 	down(&nlm_host_sema);
266 
267 	/* First, make all hosts eligible for gc */
268 	dprintk("lockd: nuking all hosts...\n");
269 	for (i = 0; i < NLM_HOST_NRHASH; i++) {
270 		for (host = nlm_hosts[i]; host; host = host->h_next)
271 			host->h_expires = jiffies - 1;
272 	}
273 
274 	/* Then, perform a garbage collection pass */
275 	nlm_gc_hosts();
276 	up(&nlm_host_sema);
277 
278 	/* complain if any hosts are left */
279 	if (nrhosts) {
280 		printk(KERN_WARNING "lockd: couldn't shutdown host module!\n");
281 		dprintk("lockd: %d hosts left:\n", nrhosts);
282 		for (i = 0; i < NLM_HOST_NRHASH; i++) {
283 			for (host = nlm_hosts[i]; host; host = host->h_next) {
284 				dprintk("       %s (cnt %d use %d exp %ld)\n",
285 					host->h_name, atomic_read(&host->h_count),
286 					host->h_inuse, host->h_expires);
287 			}
288 		}
289 	}
290 }
291 
292 /*
293  * Garbage collect any unused NLM hosts.
294  * This GC combines reference counting for async operations with
295  * mark & sweep for resources held by remote clients.
296  */
297 static void
298 nlm_gc_hosts(void)
299 {
300 	struct nlm_host	**q, *host;
301 	struct rpc_clnt	*clnt;
302 	int		i;
303 
304 	dprintk("lockd: host garbage collection\n");
305 	for (i = 0; i < NLM_HOST_NRHASH; i++) {
306 		for (host = nlm_hosts[i]; host; host = host->h_next)
307 			host->h_inuse = 0;
308 	}
309 
310 	/* Mark all hosts that hold locks, blocks or shares */
311 	nlmsvc_mark_resources();
312 
313 	for (i = 0; i < NLM_HOST_NRHASH; i++) {
314 		q = &nlm_hosts[i];
315 		while ((host = *q) != NULL) {
316 			if (atomic_read(&host->h_count) || host->h_inuse
317 			 || time_before(jiffies, host->h_expires)) {
318 				dprintk("nlm_gc_hosts skipping %s (cnt %d use %d exp %ld)\n",
319 					host->h_name, atomic_read(&host->h_count),
320 					host->h_inuse, host->h_expires);
321 				q = &host->h_next;
322 				continue;
323 			}
324 			dprintk("lockd: delete host %s\n", host->h_name);
325 			*q = host->h_next;
326 			/* Don't unmonitor hosts that have been invalidated */
327 			if (host->h_monitored && !host->h_killed)
328 				nsm_unmonitor(host);
329 			if ((clnt = host->h_rpcclnt) != NULL) {
330 				if (atomic_read(&clnt->cl_users)) {
331 					printk(KERN_WARNING
332 						"lockd: active RPC handle\n");
333 					clnt->cl_dead = 1;
334 				} else {
335 					rpc_destroy_client(host->h_rpcclnt);
336 				}
337 			}
338 			BUG_ON(!list_empty(&host->h_lockowners));
339 			kfree(host);
340 			nrhosts--;
341 		}
342 	}
343 
344 	next_gc = jiffies + NLM_HOST_COLLECT;
345 }
346 
347