xref: /openbmc/linux/fs/lockd/host.c (revision c21b37f6) 
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/slab.h>
13 #include <linux/in.h>
14 #include <linux/sunrpc/clnt.h>
15 #include <linux/sunrpc/svc.h>
16 #include <linux/lockd/lockd.h>
17 #include <linux/lockd/sm_inter.h>
18 #include <linux/mutex.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 
29 static struct hlist_head	nlm_hosts[NLM_HOST_NRHASH];
30 static unsigned long		next_gc;
31 static int			nrhosts;
32 static DEFINE_MUTEX(nlm_host_mutex);
33 
34 
35 static void			nlm_gc_hosts(void);
36 static struct nsm_handle *	__nsm_find(const struct sockaddr_in *,
37 					const char *, int, int);
38 static struct nsm_handle *	nsm_find(const struct sockaddr_in *sin,
39 					 const char *hostname,
40 					 int hostname_len);
41 
42 /*
43  * Common host lookup routine for server & client
44  */
45 static struct nlm_host *
46 nlm_lookup_host(int server, const struct sockaddr_in *sin,
47 		int proto, int version, const char *hostname,
48 		int hostname_len, const struct sockaddr_in *ssin)
49 {
50 	struct hlist_head *chain;
51 	struct hlist_node *pos;
52 	struct nlm_host	*host;
53 	struct nsm_handle *nsm = NULL;
54 	int		hash;
55 
56 	dprintk("lockd: nlm_lookup_host("NIPQUAD_FMT"->"NIPQUAD_FMT
57 			", p=%d, v=%d, my role=%s, name=%.*s)\n",
58 			NIPQUAD(ssin->sin_addr.s_addr),
59 			NIPQUAD(sin->sin_addr.s_addr), proto, version,
60 			server? "server" : "client",
61 			hostname_len,
62 			hostname? hostname : "<none>");
63 
64 
65 	hash = NLM_ADDRHASH(sin->sin_addr.s_addr);
66 
67 	/* Lock hash table */
68 	mutex_lock(&nlm_host_mutex);
69 
70 	if (time_after_eq(jiffies, next_gc))
71 		nlm_gc_hosts();
72 
73 	/* We may keep several nlm_host objects for a peer, because each
74 	 * nlm_host is identified by
75 	 * (address, protocol, version, server/client)
76 	 * We could probably simplify this a little by putting all those
77 	 * different NLM rpc_clients into one single nlm_host object.
78 	 * This would allow us to have one nlm_host per address.
79 	 */
80 	chain = &nlm_hosts[hash];
81 	hlist_for_each_entry(host, pos, chain, h_hash) {
82 		if (!nlm_cmp_addr(&host->h_addr, sin))
83 			continue;
84 
85 		/* See if we have an NSM handle for this client */
86 		if (!nsm)
87 			nsm = host->h_nsmhandle;
88 
89 		if (host->h_proto != proto)
90 			continue;
91 		if (host->h_version != version)
92 			continue;
93 		if (host->h_server != server)
94 			continue;
95 		if (!nlm_cmp_addr(&host->h_saddr, ssin))
96 			continue;
97 
98 		/* Move to head of hash chain. */
99 		hlist_del(&host->h_hash);
100 		hlist_add_head(&host->h_hash, chain);
101 
102 		nlm_get_host(host);
103 		goto out;
104 	}
105 	if (nsm)
106 		atomic_inc(&nsm->sm_count);
107 
108 	host = NULL;
109 
110 	/* Sadly, the host isn't in our hash table yet. See if
111 	 * we have an NSM handle for it. If not, create one.
112 	 */
113 	if (!nsm && !(nsm = nsm_find(sin, hostname, hostname_len)))
114 		goto out;
115 
116 	host = kzalloc(sizeof(*host), GFP_KERNEL);
117 	if (!host) {
118 		nsm_release(nsm);
119 		goto out;
120 	}
121 	host->h_name	   = nsm->sm_name;
122 	host->h_addr       = *sin;
123 	host->h_addr.sin_port = 0;	/* ouch! */
124 	host->h_saddr	   = *ssin;
125 	host->h_version    = version;
126 	host->h_proto      = proto;
127 	host->h_rpcclnt    = NULL;
128 	mutex_init(&host->h_mutex);
129 	host->h_nextrebind = jiffies + NLM_HOST_REBIND;
130 	host->h_expires    = jiffies + NLM_HOST_EXPIRE;
131 	atomic_set(&host->h_count, 1);
132 	init_waitqueue_head(&host->h_gracewait);
133 	init_rwsem(&host->h_rwsem);
134 	host->h_state      = 0;			/* pseudo NSM state */
135 	host->h_nsmstate   = 0;			/* real NSM state */
136 	host->h_nsmhandle  = nsm;
137 	host->h_server	   = server;
138 	hlist_add_head(&host->h_hash, chain);
139 	INIT_LIST_HEAD(&host->h_lockowners);
140 	spin_lock_init(&host->h_lock);
141 	INIT_LIST_HEAD(&host->h_granted);
142 	INIT_LIST_HEAD(&host->h_reclaim);
143 
144 	if (++nrhosts > NLM_HOST_MAX)
145 		next_gc = 0;
146 
147 out:
148 	mutex_unlock(&nlm_host_mutex);
149 	return host;
150 }
151 
152 /*
153  * Destroy a host
154  */
155 static void
156 nlm_destroy_host(struct nlm_host *host)
157 {
158 	struct rpc_clnt	*clnt;
159 
160 	BUG_ON(!list_empty(&host->h_lockowners));
161 	BUG_ON(atomic_read(&host->h_count));
162 
163 	/*
164 	 * Release NSM handle and unmonitor host.
165 	 */
166 	nsm_unmonitor(host);
167 
168 	clnt = host->h_rpcclnt;
169 	if (clnt != NULL)
170 		rpc_shutdown_client(clnt);
171 	kfree(host);
172 }
173 
174 /*
175  * Find an NLM server handle in the cache. If there is none, create it.
176  */
177 struct nlm_host *
178 nlmclnt_lookup_host(const struct sockaddr_in *sin, int proto, int version,
179 			const char *hostname, int hostname_len)
180 {
181 	struct sockaddr_in ssin = {0};
182 
183 	return nlm_lookup_host(0, sin, proto, version,
184 			       hostname, hostname_len, &ssin);
185 }
186 
187 /*
188  * Find an NLM client handle in the cache. If there is none, create it.
189  */
190 struct nlm_host *
191 nlmsvc_lookup_host(struct svc_rqst *rqstp,
192 			const char *hostname, int hostname_len)
193 {
194 	struct sockaddr_in ssin = {0};
195 
196 	ssin.sin_addr = rqstp->rq_daddr.addr;
197 	return nlm_lookup_host(1, svc_addr_in(rqstp),
198 			       rqstp->rq_prot, rqstp->rq_vers,
199 			       hostname, hostname_len, &ssin);
200 }
201 
202 /*
203  * Create the NLM RPC client for an NLM peer
204  */
205 struct rpc_clnt *
206 nlm_bind_host(struct nlm_host *host)
207 {
208 	struct rpc_clnt	*clnt;
209 
210 	dprintk("lockd: nlm_bind_host("NIPQUAD_FMT"->"NIPQUAD_FMT")\n",
211 			NIPQUAD(host->h_saddr.sin_addr),
212 			NIPQUAD(host->h_addr.sin_addr));
213 
214 	/* Lock host handle */
215 	mutex_lock(&host->h_mutex);
216 
217 	/* If we've already created an RPC client, check whether
218 	 * RPC rebind is required
219 	 */
220 	if ((clnt = host->h_rpcclnt) != NULL) {
221 		if (time_after_eq(jiffies, host->h_nextrebind)) {
222 			rpc_force_rebind(clnt);
223 			host->h_nextrebind = jiffies + NLM_HOST_REBIND;
224 			dprintk("lockd: next rebind in %ld jiffies\n",
225 					host->h_nextrebind - jiffies);
226 		}
227 	} else {
228 		unsigned long increment = nlmsvc_timeout;
229 		struct rpc_timeout timeparms = {
230 			.to_initval	= increment,
231 			.to_increment	= increment,
232 			.to_maxval	= increment * 6UL,
233 			.to_retries	= 5U,
234 		};
235 		struct rpc_create_args args = {
236 			.protocol	= host->h_proto,
237 			.address	= (struct sockaddr *)&host->h_addr,
238 			.addrsize	= sizeof(host->h_addr),
239 			.saddress	= (struct sockaddr *)&host->h_saddr,
240 			.timeout	= &timeparms,
241 			.servername	= host->h_name,
242 			.program	= &nlm_program,
243 			.version	= host->h_version,
244 			.authflavor	= RPC_AUTH_UNIX,
245 			.flags		= (RPC_CLNT_CREATE_HARDRTRY |
246 					   RPC_CLNT_CREATE_AUTOBIND),
247 		};
248 
249 		clnt = rpc_create(&args);
250 		if (!IS_ERR(clnt))
251 			host->h_rpcclnt = clnt;
252 		else {
253 			printk("lockd: couldn't create RPC handle for %s\n", host->h_name);
254 			clnt = NULL;
255 		}
256 	}
257 
258 	mutex_unlock(&host->h_mutex);
259 	return clnt;
260 }
261 
262 /*
263  * Force a portmap lookup of the remote lockd port
264  */
265 void
266 nlm_rebind_host(struct nlm_host *host)
267 {
268 	dprintk("lockd: rebind host %s\n", host->h_name);
269 	if (host->h_rpcclnt && time_after_eq(jiffies, host->h_nextrebind)) {
270 		rpc_force_rebind(host->h_rpcclnt);
271 		host->h_nextrebind = jiffies + NLM_HOST_REBIND;
272 	}
273 }
274 
275 /*
276  * Increment NLM host count
277  */
278 struct nlm_host * nlm_get_host(struct nlm_host *host)
279 {
280 	if (host) {
281 		dprintk("lockd: get host %s\n", host->h_name);
282 		atomic_inc(&host->h_count);
283 		host->h_expires = jiffies + NLM_HOST_EXPIRE;
284 	}
285 	return host;
286 }
287 
288 /*
289  * Release NLM host after use
290  */
291 void nlm_release_host(struct nlm_host *host)
292 {
293 	if (host != NULL) {
294 		dprintk("lockd: release host %s\n", host->h_name);
295 		BUG_ON(atomic_read(&host->h_count) < 0);
296 		if (atomic_dec_and_test(&host->h_count)) {
297 			BUG_ON(!list_empty(&host->h_lockowners));
298 			BUG_ON(!list_empty(&host->h_granted));
299 			BUG_ON(!list_empty(&host->h_reclaim));
300 		}
301 	}
302 }
303 
304 /*
305  * We were notified that the host indicated by address &sin
306  * has rebooted.
307  * Release all resources held by that peer.
308  */
309 void nlm_host_rebooted(const struct sockaddr_in *sin,
310 				const char *hostname, int hostname_len,
311 				u32 new_state)
312 {
313 	struct hlist_head *chain;
314 	struct hlist_node *pos;
315 	struct nsm_handle *nsm;
316 	struct nlm_host	*host;
317 
318 	dprintk("lockd: nlm_host_rebooted(%s, %u.%u.%u.%u)\n",
319 			hostname, NIPQUAD(sin->sin_addr));
320 
321 	/* Find the NSM handle for this peer */
322 	if (!(nsm = __nsm_find(sin, hostname, hostname_len, 0)))
323 		return;
324 
325 	/* When reclaiming locks on this peer, make sure that
326 	 * we set up a new notification */
327 	nsm->sm_monitored = 0;
328 
329 	/* Mark all hosts tied to this NSM state as having rebooted.
330 	 * We run the loop repeatedly, because we drop the host table
331 	 * lock for this.
332 	 * To avoid processing a host several times, we match the nsmstate.
333 	 */
334 again:	mutex_lock(&nlm_host_mutex);
335 	for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
336 		hlist_for_each_entry(host, pos, chain, h_hash) {
337 			if (host->h_nsmhandle == nsm
338 			 && host->h_nsmstate != new_state) {
339 				host->h_nsmstate = new_state;
340 				host->h_state++;
341 
342 				nlm_get_host(host);
343 				mutex_unlock(&nlm_host_mutex);
344 
345 				if (host->h_server) {
346 					/* We're server for this guy, just ditch
347 					 * all the locks he held. */
348 					nlmsvc_free_host_resources(host);
349 				} else {
350 					/* He's the server, initiate lock recovery. */
351 					nlmclnt_recovery(host);
352 				}
353 
354 				nlm_release_host(host);
355 				goto again;
356 			}
357 		}
358 	}
359 
360 	mutex_unlock(&nlm_host_mutex);
361 }
362 
363 /*
364  * Shut down the hosts module.
365  * Note that this routine is called only at server shutdown time.
366  */
367 void
368 nlm_shutdown_hosts(void)
369 {
370 	struct hlist_head *chain;
371 	struct hlist_node *pos;
372 	struct nlm_host	*host;
373 
374 	dprintk("lockd: shutting down host module\n");
375 	mutex_lock(&nlm_host_mutex);
376 
377 	/* First, make all hosts eligible for gc */
378 	dprintk("lockd: nuking all hosts...\n");
379 	for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
380 		hlist_for_each_entry(host, pos, chain, h_hash)
381 			host->h_expires = jiffies - 1;
382 	}
383 
384 	/* Then, perform a garbage collection pass */
385 	nlm_gc_hosts();
386 	mutex_unlock(&nlm_host_mutex);
387 
388 	/* complain if any hosts are left */
389 	if (nrhosts) {
390 		printk(KERN_WARNING "lockd: couldn't shutdown host module!\n");
391 		dprintk("lockd: %d hosts left:\n", nrhosts);
392 		for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
393 			hlist_for_each_entry(host, pos, chain, h_hash) {
394 				dprintk("       %s (cnt %d use %d exp %ld)\n",
395 					host->h_name, atomic_read(&host->h_count),
396 					host->h_inuse, host->h_expires);
397 			}
398 		}
399 	}
400 }
401 
402 /*
403  * Garbage collect any unused NLM hosts.
404  * This GC combines reference counting for async operations with
405  * mark & sweep for resources held by remote clients.
406  */
407 static void
408 nlm_gc_hosts(void)
409 {
410 	struct hlist_head *chain;
411 	struct hlist_node *pos, *next;
412 	struct nlm_host	*host;
413 
414 	dprintk("lockd: host garbage collection\n");
415 	for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
416 		hlist_for_each_entry(host, pos, chain, h_hash)
417 			host->h_inuse = 0;
418 	}
419 
420 	/* Mark all hosts that hold locks, blocks or shares */
421 	nlmsvc_mark_resources();
422 
423 	for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
424 		hlist_for_each_entry_safe(host, pos, next, chain, h_hash) {
425 			if (atomic_read(&host->h_count) || host->h_inuse
426 			 || time_before(jiffies, host->h_expires)) {
427 				dprintk("nlm_gc_hosts skipping %s (cnt %d use %d exp %ld)\n",
428 					host->h_name, atomic_read(&host->h_count),
429 					host->h_inuse, host->h_expires);
430 				continue;
431 			}
432 			dprintk("lockd: delete host %s\n", host->h_name);
433 			hlist_del_init(&host->h_hash);
434 
435 			nlm_destroy_host(host);
436 			nrhosts--;
437 		}
438 	}
439 
440 	next_gc = jiffies + NLM_HOST_COLLECT;
441 }
442 
443 
444 /*
445  * Manage NSM handles
446  */
447 static LIST_HEAD(nsm_handles);
448 static DEFINE_MUTEX(nsm_mutex);
449 
450 static struct nsm_handle *
451 __nsm_find(const struct sockaddr_in *sin,
452 		const char *hostname, int hostname_len,
453 		int create)
454 {
455 	struct nsm_handle *nsm = NULL;
456 	struct list_head *pos;
457 
458 	if (!sin)
459 		return NULL;
460 
461 	if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
462 		if (printk_ratelimit()) {
463 			printk(KERN_WARNING "Invalid hostname \"%.*s\" "
464 					    "in NFS lock request\n",
465 				hostname_len, hostname);
466 		}
467 		return NULL;
468 	}
469 
470 	mutex_lock(&nsm_mutex);
471 	list_for_each(pos, &nsm_handles) {
472 		nsm = list_entry(pos, struct nsm_handle, sm_link);
473 
474 		if (hostname && nsm_use_hostnames) {
475 			if (strlen(nsm->sm_name) != hostname_len
476 			 || memcmp(nsm->sm_name, hostname, hostname_len))
477 				continue;
478 		} else if (!nlm_cmp_addr(&nsm->sm_addr, sin))
479 			continue;
480 		atomic_inc(&nsm->sm_count);
481 		goto out;
482 	}
483 
484 	if (!create) {
485 		nsm = NULL;
486 		goto out;
487 	}
488 
489 	nsm = kzalloc(sizeof(*nsm) + hostname_len + 1, GFP_KERNEL);
490 	if (nsm != NULL) {
491 		nsm->sm_addr = *sin;
492 		nsm->sm_name = (char *) (nsm + 1);
493 		memcpy(nsm->sm_name, hostname, hostname_len);
494 		nsm->sm_name[hostname_len] = '\0';
495 		atomic_set(&nsm->sm_count, 1);
496 
497 		list_add(&nsm->sm_link, &nsm_handles);
498 	}
499 
500 out:
501 	mutex_unlock(&nsm_mutex);
502 	return nsm;
503 }
504 
505 static struct nsm_handle *
506 nsm_find(const struct sockaddr_in *sin, const char *hostname, int hostname_len)
507 {
508 	return __nsm_find(sin, hostname, hostname_len, 1);
509 }
510 
511 /*
512  * Release an NSM handle
513  */
514 void
515 nsm_release(struct nsm_handle *nsm)
516 {
517 	if (!nsm)
518 		return;
519 	if (atomic_dec_and_test(&nsm->sm_count)) {
520 		mutex_lock(&nsm_mutex);
521 		if (atomic_read(&nsm->sm_count) == 0) {
522 			list_del(&nsm->sm_link);
523 			kfree(nsm);
524 		}
525 		mutex_unlock(&nsm_mutex);
526 	}
527 }
528