xref: /openbmc/linux/fs/nfsd/nfssvc.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
1 /*
2  * linux/fs/nfsd/nfssvc.c
3  *
4  * Central processing for nfsd.
5  *
6  * Authors:	Olaf Kirch (okir@monad.swb.de)
7  *
8  * Copyright (C) 1995, 1996, 1997 Olaf Kirch <okir@monad.swb.de>
9  */
10 
11 #include <linux/config.h>
12 #include <linux/module.h>
13 
14 #include <linux/time.h>
15 #include <linux/errno.h>
16 #include <linux/nfs.h>
17 #include <linux/in.h>
18 #include <linux/uio.h>
19 #include <linux/unistd.h>
20 #include <linux/slab.h>
21 #include <linux/smp.h>
22 #include <linux/smp_lock.h>
23 #include <linux/fs_struct.h>
24 
25 #include <linux/sunrpc/types.h>
26 #include <linux/sunrpc/stats.h>
27 #include <linux/sunrpc/svc.h>
28 #include <linux/sunrpc/svcsock.h>
29 #include <linux/sunrpc/cache.h>
30 #include <linux/nfsd/nfsd.h>
31 #include <linux/nfsd/stats.h>
32 #include <linux/nfsd/cache.h>
33 #include <linux/lockd/bind.h>
34 #include <linux/nfsacl.h>
35 
36 #define NFSDDBG_FACILITY	NFSDDBG_SVC
37 
38 /* these signals will be delivered to an nfsd thread
39  * when handling a request
40  */
41 #define ALLOWED_SIGS	(sigmask(SIGKILL))
42 /* these signals will be delivered to an nfsd thread
43  * when not handling a request. i.e. when waiting
44  */
45 #define SHUTDOWN_SIGS	(sigmask(SIGKILL) | sigmask(SIGHUP) | sigmask(SIGINT) | sigmask(SIGQUIT))
46 /* if the last thread dies with SIGHUP, then the exports table is
47  * left unchanged ( like 2.4-{0-9} ).  Any other signal will clear
48  * the exports table (like 2.2).
49  */
50 #define	SIG_NOCLEAN	SIGHUP
51 
52 extern struct svc_program	nfsd_program;
53 static void			nfsd(struct svc_rqst *rqstp);
54 struct timeval			nfssvc_boot;
55 static struct svc_serv 		*nfsd_serv;
56 static atomic_t			nfsd_busy;
57 static unsigned long		nfsd_last_call;
58 static DEFINE_SPINLOCK(nfsd_call_lock);
59 
60 struct nfsd_list {
61 	struct list_head 	list;
62 	struct task_struct	*task;
63 };
64 static struct list_head nfsd_list = LIST_HEAD_INIT(nfsd_list);
65 
66 /*
67  * Maximum number of nfsd processes
68  */
69 #define	NFSD_MAXSERVS		8192
70 
71 int nfsd_nrthreads(void)
72 {
73 	if (nfsd_serv == NULL)
74 		return 0;
75 	else
76 		return nfsd_serv->sv_nrthreads;
77 }
78 
79 int
80 nfsd_svc(unsigned short port, int nrservs)
81 {
82 	int	error;
83 	int	none_left;
84 	struct list_head *victim;
85 
86 	lock_kernel();
87 	dprintk("nfsd: creating service\n");
88 	error = -EINVAL;
89 	if (nrservs <= 0)
90 		nrservs = 0;
91 	if (nrservs > NFSD_MAXSERVS)
92 		nrservs = NFSD_MAXSERVS;
93 
94 	/* Readahead param cache - will no-op if it already exists */
95 	error =	nfsd_racache_init(2*nrservs);
96 	if (error<0)
97 		goto out;
98 	error = nfs4_state_start();
99 	if (error<0)
100 		goto out;
101 	if (!nfsd_serv) {
102 		atomic_set(&nfsd_busy, 0);
103 		error = -ENOMEM;
104 		nfsd_serv = svc_create(&nfsd_program, NFSD_BUFSIZE);
105 		if (nfsd_serv == NULL)
106 			goto out;
107 		error = svc_makesock(nfsd_serv, IPPROTO_UDP, port);
108 		if (error < 0)
109 			goto failure;
110 
111 #ifdef CONFIG_NFSD_TCP
112 		error = svc_makesock(nfsd_serv, IPPROTO_TCP, port);
113 		if (error < 0)
114 			goto failure;
115 #endif
116 		do_gettimeofday(&nfssvc_boot);		/* record boot time */
117 	} else
118 		nfsd_serv->sv_nrthreads++;
119 	nrservs -= (nfsd_serv->sv_nrthreads-1);
120 	while (nrservs > 0) {
121 		nrservs--;
122 		__module_get(THIS_MODULE);
123 		error = svc_create_thread(nfsd, nfsd_serv);
124 		if (error < 0) {
125 			module_put(THIS_MODULE);
126 			break;
127 		}
128 	}
129 	victim = nfsd_list.next;
130 	while (nrservs < 0 && victim != &nfsd_list) {
131 		struct nfsd_list *nl =
132 			list_entry(victim,struct nfsd_list, list);
133 		victim = victim->next;
134 		send_sig(SIG_NOCLEAN, nl->task, 1);
135 		nrservs++;
136 	}
137  failure:
138 	none_left = (nfsd_serv->sv_nrthreads == 1);
139 	svc_destroy(nfsd_serv);		/* Release server */
140 	if (none_left) {
141 		nfsd_serv = NULL;
142 		nfsd_racache_shutdown();
143 		nfs4_state_shutdown();
144 	}
145  out:
146 	unlock_kernel();
147 	return error;
148 }
149 
150 static inline void
151 update_thread_usage(int busy_threads)
152 {
153 	unsigned long prev_call;
154 	unsigned long diff;
155 	int decile;
156 
157 	spin_lock(&nfsd_call_lock);
158 	prev_call = nfsd_last_call;
159 	nfsd_last_call = jiffies;
160 	decile = busy_threads*10/nfsdstats.th_cnt;
161 	if (decile>0 && decile <= 10) {
162 		diff = nfsd_last_call - prev_call;
163 		if ( (nfsdstats.th_usage[decile-1] += diff) >= NFSD_USAGE_WRAP)
164 			nfsdstats.th_usage[decile-1] -= NFSD_USAGE_WRAP;
165 		if (decile == 10)
166 			nfsdstats.th_fullcnt++;
167 	}
168 	spin_unlock(&nfsd_call_lock);
169 }
170 
171 /*
172  * This is the NFS server kernel thread
173  */
174 static void
175 nfsd(struct svc_rqst *rqstp)
176 {
177 	struct svc_serv	*serv = rqstp->rq_server;
178 	struct fs_struct *fsp;
179 	int		err;
180 	struct nfsd_list me;
181 	sigset_t shutdown_mask, allowed_mask;
182 
183 	/* Lock module and set up kernel thread */
184 	lock_kernel();
185 	daemonize("nfsd");
186 
187 	/* After daemonize() this kernel thread shares current->fs
188 	 * with the init process. We need to create files with a
189 	 * umask of 0 instead of init's umask. */
190 	fsp = copy_fs_struct(current->fs);
191 	if (!fsp) {
192 		printk("Unable to start nfsd thread: out of memory\n");
193 		goto out;
194 	}
195 	exit_fs(current);
196 	current->fs = fsp;
197 	current->fs->umask = 0;
198 
199 	siginitsetinv(&shutdown_mask, SHUTDOWN_SIGS);
200 	siginitsetinv(&allowed_mask, ALLOWED_SIGS);
201 
202 	nfsdstats.th_cnt++;
203 
204 	lockd_up();				/* start lockd */
205 
206 	me.task = current;
207 	list_add(&me.list, &nfsd_list);
208 
209 	unlock_kernel();
210 
211 	/*
212 	 * We want less throttling in balance_dirty_pages() so that nfs to
213 	 * localhost doesn't cause nfsd to lock up due to all the client's
214 	 * dirty pages.
215 	 */
216 	current->flags |= PF_LESS_THROTTLE;
217 
218 	/*
219 	 * The main request loop
220 	 */
221 	for (;;) {
222 		/* Block all but the shutdown signals */
223 		sigprocmask(SIG_SETMASK, &shutdown_mask, NULL);
224 
225 		/*
226 		 * Find a socket with data available and call its
227 		 * recvfrom routine.
228 		 */
229 		while ((err = svc_recv(serv, rqstp,
230 				       60*60*HZ)) == -EAGAIN)
231 			;
232 		if (err < 0)
233 			break;
234 		update_thread_usage(atomic_read(&nfsd_busy));
235 		atomic_inc(&nfsd_busy);
236 
237 		/* Lock the export hash tables for reading. */
238 		exp_readlock();
239 
240 		/* Process request with signals blocked.  */
241 		sigprocmask(SIG_SETMASK, &allowed_mask, NULL);
242 
243 		svc_process(serv, rqstp);
244 
245 		/* Unlock export hash tables */
246 		exp_readunlock();
247 		update_thread_usage(atomic_read(&nfsd_busy));
248 		atomic_dec(&nfsd_busy);
249 	}
250 
251 	if (err != -EINTR) {
252 		printk(KERN_WARNING "nfsd: terminating on error %d\n", -err);
253 	} else {
254 		unsigned int	signo;
255 
256 		for (signo = 1; signo <= _NSIG; signo++)
257 			if (sigismember(&current->pending.signal, signo) &&
258 			    !sigismember(&current->blocked, signo))
259 				break;
260 		err = signo;
261 	}
262 	/* Clear signals before calling lockd_down() and svc_exit_thread() */
263 	flush_signals(current);
264 
265 	lock_kernel();
266 
267 	/* Release lockd */
268 	lockd_down();
269 
270 	/* Check if this is last thread */
271 	if (serv->sv_nrthreads==1) {
272 
273 		printk(KERN_WARNING "nfsd: last server has exited\n");
274 		if (err != SIG_NOCLEAN) {
275 			printk(KERN_WARNING "nfsd: unexporting all filesystems\n");
276 			nfsd_export_flush();
277 		}
278 		nfsd_serv = NULL;
279 	        nfsd_racache_shutdown();	/* release read-ahead cache */
280 		nfs4_state_shutdown();
281 	}
282 	list_del(&me.list);
283 	nfsdstats.th_cnt --;
284 
285 out:
286 	/* Release the thread */
287 	svc_exit_thread(rqstp);
288 
289 	/* Release module */
290 	unlock_kernel();
291 	module_put_and_exit(0);
292 }
293 
294 int
295 nfsd_dispatch(struct svc_rqst *rqstp, u32 *statp)
296 {
297 	struct svc_procedure	*proc;
298 	kxdrproc_t		xdr;
299 	u32			nfserr;
300 	u32			*nfserrp;
301 
302 	dprintk("nfsd_dispatch: vers %d proc %d\n",
303 				rqstp->rq_vers, rqstp->rq_proc);
304 	proc = rqstp->rq_procinfo;
305 
306 	/* Check whether we have this call in the cache. */
307 	switch (nfsd_cache_lookup(rqstp, proc->pc_cachetype)) {
308 	case RC_INTR:
309 	case RC_DROPIT:
310 		return 0;
311 	case RC_REPLY:
312 		return 1;
313 	case RC_DOIT:;
314 		/* do it */
315 	}
316 
317 	/* Decode arguments */
318 	xdr = proc->pc_decode;
319 	if (xdr && !xdr(rqstp, (u32*)rqstp->rq_arg.head[0].iov_base,
320 			rqstp->rq_argp)) {
321 		dprintk("nfsd: failed to decode arguments!\n");
322 		nfsd_cache_update(rqstp, RC_NOCACHE, NULL);
323 		*statp = rpc_garbage_args;
324 		return 1;
325 	}
326 
327 	/* need to grab the location to store the status, as
328 	 * nfsv4 does some encoding while processing
329 	 */
330 	nfserrp = rqstp->rq_res.head[0].iov_base
331 		+ rqstp->rq_res.head[0].iov_len;
332 	rqstp->rq_res.head[0].iov_len += sizeof(u32);
333 
334 	/* Now call the procedure handler, and encode NFS status. */
335 	nfserr = proc->pc_func(rqstp, rqstp->rq_argp, rqstp->rq_resp);
336 	if (nfserr == nfserr_jukebox && rqstp->rq_vers == 2)
337 		nfserr = nfserr_dropit;
338 	if (nfserr == nfserr_dropit) {
339 		dprintk("nfsd: Dropping request due to malloc failure!\n");
340 		nfsd_cache_update(rqstp, RC_NOCACHE, NULL);
341 		return 0;
342 	}
343 
344 	if (rqstp->rq_proc != 0)
345 		*nfserrp++ = nfserr;
346 
347 	/* Encode result.
348 	 * For NFSv2, additional info is never returned in case of an error.
349 	 */
350 	if (!(nfserr && rqstp->rq_vers == 2)) {
351 		xdr = proc->pc_encode;
352 		if (xdr && !xdr(rqstp, nfserrp,
353 				rqstp->rq_resp)) {
354 			/* Failed to encode result. Release cache entry */
355 			dprintk("nfsd: failed to encode result!\n");
356 			nfsd_cache_update(rqstp, RC_NOCACHE, NULL);
357 			*statp = rpc_system_err;
358 			return 1;
359 		}
360 	}
361 
362 	/* Store reply in cache. */
363 	nfsd_cache_update(rqstp, proc->pc_cachetype, statp + 1);
364 	return 1;
365 }
366 
367 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
368 static struct svc_stat	nfsd_acl_svcstats;
369 static struct svc_version *	nfsd_acl_version[] = {
370 	[2] = &nfsd_acl_version2,
371 	[3] = &nfsd_acl_version3,
372 };
373 
374 #define NFSD_ACL_NRVERS		(sizeof(nfsd_acl_version)/sizeof(nfsd_acl_version[0]))
375 static struct svc_program	nfsd_acl_program = {
376 	.pg_prog		= NFS_ACL_PROGRAM,
377 	.pg_nvers		= NFSD_ACL_NRVERS,
378 	.pg_vers		= nfsd_acl_version,
379 	.pg_name		= "nfsd",
380 	.pg_class		= "nfsd",
381 	.pg_stats		= &nfsd_acl_svcstats,
382 };
383 
384 static struct svc_stat	nfsd_acl_svcstats = {
385 	.program	= &nfsd_acl_program,
386 };
387 
388 #define nfsd_acl_program_p	&nfsd_acl_program
389 #else
390 #define nfsd_acl_program_p	NULL
391 #endif /* defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL) */
392 
393 extern struct svc_version nfsd_version2, nfsd_version3, nfsd_version4;
394 
395 static struct svc_version *	nfsd_version[] = {
396 	[2] = &nfsd_version2,
397 #if defined(CONFIG_NFSD_V3)
398 	[3] = &nfsd_version3,
399 #endif
400 #if defined(CONFIG_NFSD_V4)
401 	[4] = &nfsd_version4,
402 #endif
403 };
404 
405 #define NFSD_NRVERS		(sizeof(nfsd_version)/sizeof(nfsd_version[0]))
406 struct svc_program		nfsd_program = {
407 	.pg_next		= nfsd_acl_program_p,
408 	.pg_prog		= NFS_PROGRAM,		/* program number */
409 	.pg_nvers		= NFSD_NRVERS,		/* nr of entries in nfsd_version */
410 	.pg_vers		= nfsd_version,		/* version table */
411 	.pg_name		= "nfsd",		/* program name */
412 	.pg_class		= "nfsd",		/* authentication class */
413 	.pg_stats		= &nfsd_svcstats,	/* version table */
414 	.pg_authenticate	= &svc_set_client,	/* export authentication */
415 
416 };
417