xref: /openbmc/linux/fs/nfsd/nfssvc.c (revision 9d56dd3b083a3bec56e9da35ce07baca81030b03)
1 /*
2  * Central processing for nfsd.
3  *
4  * Authors:	Olaf Kirch (okir@monad.swb.de)
5  *
6  * Copyright (C) 1995, 1996, 1997 Olaf Kirch <okir@monad.swb.de>
7  */
8 
9 #include <linux/sched.h>
10 #include <linux/freezer.h>
11 #include <linux/fs_struct.h>
12 #include <linux/swap.h>
13 
14 #include <linux/sunrpc/stats.h>
15 #include <linux/sunrpc/svcsock.h>
16 #include <linux/lockd/bind.h>
17 #include <linux/nfsacl.h>
18 #include <linux/seq_file.h>
19 #include "nfsd.h"
20 #include "cache.h"
21 #include "vfs.h"
22 
23 #define NFSDDBG_FACILITY	NFSDDBG_SVC
24 
25 extern struct svc_program	nfsd_program;
26 static int			nfsd(void *vrqstp);
27 struct timeval			nfssvc_boot;
28 
29 /*
30  * nfsd_mutex protects nfsd_serv -- both the pointer itself and the members
31  * of the svc_serv struct. In particular, ->sv_nrthreads but also to some
32  * extent ->sv_temp_socks and ->sv_permsocks. It also protects nfsdstats.th_cnt
33  *
34  * If (out side the lock) nfsd_serv is non-NULL, then it must point to a
35  * properly initialised 'struct svc_serv' with ->sv_nrthreads > 0. That number
36  * of nfsd threads must exist and each must listed in ->sp_all_threads in each
37  * entry of ->sv_pools[].
38  *
39  * Transitions of the thread count between zero and non-zero are of particular
40  * interest since the svc_serv needs to be created and initialized at that
41  * point, or freed.
42  *
43  * Finally, the nfsd_mutex also protects some of the global variables that are
44  * accessed when nfsd starts and that are settable via the write_* routines in
45  * nfsctl.c. In particular:
46  *
47  *	user_recovery_dirname
48  *	user_lease_time
49  *	nfsd_versions
50  */
51 DEFINE_MUTEX(nfsd_mutex);
52 struct svc_serv 		*nfsd_serv;
53 
54 /*
55  * nfsd_drc_lock protects nfsd_drc_max_pages and nfsd_drc_pages_used.
56  * nfsd_drc_max_pages limits the total amount of memory available for
57  * version 4.1 DRC caches.
58  * nfsd_drc_pages_used tracks the current version 4.1 DRC memory usage.
59  */
60 spinlock_t	nfsd_drc_lock;
61 unsigned int	nfsd_drc_max_mem;
62 unsigned int	nfsd_drc_mem_used;
63 
64 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
65 static struct svc_stat	nfsd_acl_svcstats;
66 static struct svc_version *	nfsd_acl_version[] = {
67 	[2] = &nfsd_acl_version2,
68 	[3] = &nfsd_acl_version3,
69 };
70 
71 #define NFSD_ACL_MINVERS            2
72 #define NFSD_ACL_NRVERS		ARRAY_SIZE(nfsd_acl_version)
73 static struct svc_version *nfsd_acl_versions[NFSD_ACL_NRVERS];
74 
75 static struct svc_program	nfsd_acl_program = {
76 	.pg_prog		= NFS_ACL_PROGRAM,
77 	.pg_nvers		= NFSD_ACL_NRVERS,
78 	.pg_vers		= nfsd_acl_versions,
79 	.pg_name		= "nfsacl",
80 	.pg_class		= "nfsd",
81 	.pg_stats		= &nfsd_acl_svcstats,
82 	.pg_authenticate	= &svc_set_client,
83 };
84 
85 static struct svc_stat	nfsd_acl_svcstats = {
86 	.program	= &nfsd_acl_program,
87 };
88 #endif /* defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL) */
89 
90 static struct svc_version *	nfsd_version[] = {
91 	[2] = &nfsd_version2,
92 #if defined(CONFIG_NFSD_V3)
93 	[3] = &nfsd_version3,
94 #endif
95 #if defined(CONFIG_NFSD_V4)
96 	[4] = &nfsd_version4,
97 #endif
98 };
99 
100 #define NFSD_MINVERS    	2
101 #define NFSD_NRVERS		ARRAY_SIZE(nfsd_version)
102 static struct svc_version *nfsd_versions[NFSD_NRVERS];
103 
104 struct svc_program		nfsd_program = {
105 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
106 	.pg_next		= &nfsd_acl_program,
107 #endif
108 	.pg_prog		= NFS_PROGRAM,		/* program number */
109 	.pg_nvers		= NFSD_NRVERS,		/* nr of entries in nfsd_version */
110 	.pg_vers		= nfsd_versions,	/* version table */
111 	.pg_name		= "nfsd",		/* program name */
112 	.pg_class		= "nfsd",		/* authentication class */
113 	.pg_stats		= &nfsd_svcstats,	/* version table */
114 	.pg_authenticate	= &svc_set_client,	/* export authentication */
115 
116 };
117 
118 u32 nfsd_supported_minorversion;
119 
120 int nfsd_vers(int vers, enum vers_op change)
121 {
122 	if (vers < NFSD_MINVERS || vers >= NFSD_NRVERS)
123 		return -1;
124 	switch(change) {
125 	case NFSD_SET:
126 		nfsd_versions[vers] = nfsd_version[vers];
127 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
128 		if (vers < NFSD_ACL_NRVERS)
129 			nfsd_acl_versions[vers] = nfsd_acl_version[vers];
130 #endif
131 		break;
132 	case NFSD_CLEAR:
133 		nfsd_versions[vers] = NULL;
134 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
135 		if (vers < NFSD_ACL_NRVERS)
136 			nfsd_acl_versions[vers] = NULL;
137 #endif
138 		break;
139 	case NFSD_TEST:
140 		return nfsd_versions[vers] != NULL;
141 	case NFSD_AVAIL:
142 		return nfsd_version[vers] != NULL;
143 	}
144 	return 0;
145 }
146 
147 int nfsd_minorversion(u32 minorversion, enum vers_op change)
148 {
149 	if (minorversion > NFSD_SUPPORTED_MINOR_VERSION)
150 		return -1;
151 	switch(change) {
152 	case NFSD_SET:
153 		nfsd_supported_minorversion = minorversion;
154 		break;
155 	case NFSD_CLEAR:
156 		if (minorversion == 0)
157 			return -1;
158 		nfsd_supported_minorversion = minorversion - 1;
159 		break;
160 	case NFSD_TEST:
161 		return minorversion <= nfsd_supported_minorversion;
162 	case NFSD_AVAIL:
163 		return minorversion <= NFSD_SUPPORTED_MINOR_VERSION;
164 	}
165 	return 0;
166 }
167 
168 /*
169  * Maximum number of nfsd processes
170  */
171 #define	NFSD_MAXSERVS		8192
172 
173 int nfsd_nrthreads(void)
174 {
175 	int rv = 0;
176 	mutex_lock(&nfsd_mutex);
177 	if (nfsd_serv)
178 		rv = nfsd_serv->sv_nrthreads;
179 	mutex_unlock(&nfsd_mutex);
180 	return rv;
181 }
182 
183 static void nfsd_last_thread(struct svc_serv *serv)
184 {
185 	/* When last nfsd thread exits we need to do some clean-up */
186 	struct svc_xprt *xprt;
187 	list_for_each_entry(xprt, &serv->sv_permsocks, xpt_list)
188 		lockd_down();
189 	nfsd_serv = NULL;
190 	nfsd_racache_shutdown();
191 	nfs4_state_shutdown();
192 
193 	printk(KERN_WARNING "nfsd: last server has exited, flushing export "
194 			    "cache\n");
195 	nfsd_export_flush();
196 }
197 
198 void nfsd_reset_versions(void)
199 {
200 	int found_one = 0;
201 	int i;
202 
203 	for (i = NFSD_MINVERS; i < NFSD_NRVERS; i++) {
204 		if (nfsd_program.pg_vers[i])
205 			found_one = 1;
206 	}
207 
208 	if (!found_one) {
209 		for (i = NFSD_MINVERS; i < NFSD_NRVERS; i++)
210 			nfsd_program.pg_vers[i] = nfsd_version[i];
211 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
212 		for (i = NFSD_ACL_MINVERS; i < NFSD_ACL_NRVERS; i++)
213 			nfsd_acl_program.pg_vers[i] =
214 				nfsd_acl_version[i];
215 #endif
216 	}
217 }
218 
219 /*
220  * Each session guarantees a negotiated per slot memory cache for replies
221  * which in turn consumes memory beyond the v2/v3/v4.0 server. A dedicated
222  * NFSv4.1 server might want to use more memory for a DRC than a machine
223  * with mutiple services.
224  *
225  * Impose a hard limit on the number of pages for the DRC which varies
226  * according to the machines free pages. This is of course only a default.
227  *
228  * For now this is a #defined shift which could be under admin control
229  * in the future.
230  */
231 static void set_max_drc(void)
232 {
233 	#define NFSD_DRC_SIZE_SHIFT	10
234 	nfsd_drc_max_mem = (nr_free_buffer_pages()
235 					>> NFSD_DRC_SIZE_SHIFT) * PAGE_SIZE;
236 	nfsd_drc_mem_used = 0;
237 	spin_lock_init(&nfsd_drc_lock);
238 	dprintk("%s nfsd_drc_max_mem %u \n", __func__, nfsd_drc_max_mem);
239 }
240 
241 int nfsd_create_serv(void)
242 {
243 	int err = 0;
244 
245 	WARN_ON(!mutex_is_locked(&nfsd_mutex));
246 	if (nfsd_serv) {
247 		svc_get(nfsd_serv);
248 		return 0;
249 	}
250 	if (nfsd_max_blksize == 0) {
251 		/* choose a suitable default */
252 		struct sysinfo i;
253 		si_meminfo(&i);
254 		/* Aim for 1/4096 of memory per thread
255 		 * This gives 1MB on 4Gig machines
256 		 * But only uses 32K on 128M machines.
257 		 * Bottom out at 8K on 32M and smaller.
258 		 * Of course, this is only a default.
259 		 */
260 		nfsd_max_blksize = NFSSVC_MAXBLKSIZE;
261 		i.totalram <<= PAGE_SHIFT - 12;
262 		while (nfsd_max_blksize > i.totalram &&
263 		       nfsd_max_blksize >= 8*1024*2)
264 			nfsd_max_blksize /= 2;
265 	}
266 
267 	nfsd_serv = svc_create_pooled(&nfsd_program, nfsd_max_blksize,
268 				      nfsd_last_thread, nfsd, THIS_MODULE);
269 	if (nfsd_serv == NULL)
270 		err = -ENOMEM;
271 	else
272 		set_max_drc();
273 
274 	do_gettimeofday(&nfssvc_boot);		/* record boot time */
275 	return err;
276 }
277 
278 static int nfsd_init_socks(int port)
279 {
280 	int error;
281 	if (!list_empty(&nfsd_serv->sv_permsocks))
282 		return 0;
283 
284 	error = svc_create_xprt(nfsd_serv, "udp", PF_INET, port,
285 					SVC_SOCK_DEFAULTS);
286 	if (error < 0)
287 		return error;
288 
289 	error = lockd_up();
290 	if (error < 0)
291 		return error;
292 
293 	error = svc_create_xprt(nfsd_serv, "tcp", PF_INET, port,
294 					SVC_SOCK_DEFAULTS);
295 	if (error < 0)
296 		return error;
297 
298 	error = lockd_up();
299 	if (error < 0)
300 		return error;
301 
302 	return 0;
303 }
304 
305 int nfsd_nrpools(void)
306 {
307 	if (nfsd_serv == NULL)
308 		return 0;
309 	else
310 		return nfsd_serv->sv_nrpools;
311 }
312 
313 int nfsd_get_nrthreads(int n, int *nthreads)
314 {
315 	int i = 0;
316 
317 	if (nfsd_serv != NULL) {
318 		for (i = 0; i < nfsd_serv->sv_nrpools && i < n; i++)
319 			nthreads[i] = nfsd_serv->sv_pools[i].sp_nrthreads;
320 	}
321 
322 	return 0;
323 }
324 
325 int nfsd_set_nrthreads(int n, int *nthreads)
326 {
327 	int i = 0;
328 	int tot = 0;
329 	int err = 0;
330 
331 	WARN_ON(!mutex_is_locked(&nfsd_mutex));
332 
333 	if (nfsd_serv == NULL || n <= 0)
334 		return 0;
335 
336 	if (n > nfsd_serv->sv_nrpools)
337 		n = nfsd_serv->sv_nrpools;
338 
339 	/* enforce a global maximum number of threads */
340 	tot = 0;
341 	for (i = 0; i < n; i++) {
342 		if (nthreads[i] > NFSD_MAXSERVS)
343 			nthreads[i] = NFSD_MAXSERVS;
344 		tot += nthreads[i];
345 	}
346 	if (tot > NFSD_MAXSERVS) {
347 		/* total too large: scale down requested numbers */
348 		for (i = 0; i < n && tot > 0; i++) {
349 		    	int new = nthreads[i] * NFSD_MAXSERVS / tot;
350 			tot -= (nthreads[i] - new);
351 			nthreads[i] = new;
352 		}
353 		for (i = 0; i < n && tot > 0; i++) {
354 			nthreads[i]--;
355 			tot--;
356 		}
357 	}
358 
359 	/*
360 	 * There must always be a thread in pool 0; the admin
361 	 * can't shut down NFS completely using pool_threads.
362 	 */
363 	if (nthreads[0] == 0)
364 		nthreads[0] = 1;
365 
366 	/* apply the new numbers */
367 	svc_get(nfsd_serv);
368 	for (i = 0; i < n; i++) {
369 		err = svc_set_num_threads(nfsd_serv, &nfsd_serv->sv_pools[i],
370 				    	  nthreads[i]);
371 		if (err)
372 			break;
373 	}
374 	svc_destroy(nfsd_serv);
375 
376 	return err;
377 }
378 
379 int
380 nfsd_svc(unsigned short port, int nrservs)
381 {
382 	int	error;
383 
384 	mutex_lock(&nfsd_mutex);
385 	dprintk("nfsd: creating service\n");
386 	if (nrservs <= 0)
387 		nrservs = 0;
388 	if (nrservs > NFSD_MAXSERVS)
389 		nrservs = NFSD_MAXSERVS;
390 	error = 0;
391 	if (nrservs == 0 && nfsd_serv == NULL)
392 		goto out;
393 
394 	/* Readahead param cache - will no-op if it already exists */
395 	error =	nfsd_racache_init(2*nrservs);
396 	if (error<0)
397 		goto out;
398 	error = nfs4_state_start();
399 	if (error)
400 		goto out;
401 
402 	nfsd_reset_versions();
403 
404 	error = nfsd_create_serv();
405 
406 	if (error)
407 		goto out;
408 	error = nfsd_init_socks(port);
409 	if (error)
410 		goto failure;
411 
412 	error = svc_set_num_threads(nfsd_serv, NULL, nrservs);
413 	if (error == 0)
414 		/* We are holding a reference to nfsd_serv which
415 		 * we don't want to count in the return value,
416 		 * so subtract 1
417 		 */
418 		error = nfsd_serv->sv_nrthreads - 1;
419  failure:
420 	svc_destroy(nfsd_serv);		/* Release server */
421  out:
422 	mutex_unlock(&nfsd_mutex);
423 	return error;
424 }
425 
426 
427 /*
428  * This is the NFS server kernel thread
429  */
430 static int
431 nfsd(void *vrqstp)
432 {
433 	struct svc_rqst *rqstp = (struct svc_rqst *) vrqstp;
434 	int err, preverr = 0;
435 
436 	/* Lock module and set up kernel thread */
437 	mutex_lock(&nfsd_mutex);
438 
439 	/* At this point, the thread shares current->fs
440 	 * with the init process. We need to create files with a
441 	 * umask of 0 instead of init's umask. */
442 	if (unshare_fs_struct() < 0) {
443 		printk("Unable to start nfsd thread: out of memory\n");
444 		goto out;
445 	}
446 
447 	current->fs->umask = 0;
448 
449 	/*
450 	 * thread is spawned with all signals set to SIG_IGN, re-enable
451 	 * the ones that will bring down the thread
452 	 */
453 	allow_signal(SIGKILL);
454 	allow_signal(SIGHUP);
455 	allow_signal(SIGINT);
456 	allow_signal(SIGQUIT);
457 
458 	nfsdstats.th_cnt++;
459 	mutex_unlock(&nfsd_mutex);
460 
461 	/*
462 	 * We want less throttling in balance_dirty_pages() so that nfs to
463 	 * localhost doesn't cause nfsd to lock up due to all the client's
464 	 * dirty pages.
465 	 */
466 	current->flags |= PF_LESS_THROTTLE;
467 	set_freezable();
468 
469 	/*
470 	 * The main request loop
471 	 */
472 	for (;;) {
473 		/*
474 		 * Find a socket with data available and call its
475 		 * recvfrom routine.
476 		 */
477 		while ((err = svc_recv(rqstp, 60*60*HZ)) == -EAGAIN)
478 			;
479 		if (err == -EINTR)
480 			break;
481 		else if (err < 0) {
482 			if (err != preverr) {
483 				printk(KERN_WARNING "%s: unexpected error "
484 					"from svc_recv (%d)\n", __func__, -err);
485 				preverr = err;
486 			}
487 			schedule_timeout_uninterruptible(HZ);
488 			continue;
489 		}
490 
491 
492 		/* Lock the export hash tables for reading. */
493 		exp_readlock();
494 
495 		validate_process_creds();
496 		svc_process(rqstp);
497 		validate_process_creds();
498 
499 		/* Unlock export hash tables */
500 		exp_readunlock();
501 	}
502 
503 	/* Clear signals before calling svc_exit_thread() */
504 	flush_signals(current);
505 
506 	mutex_lock(&nfsd_mutex);
507 	nfsdstats.th_cnt --;
508 
509 out:
510 	/* Release the thread */
511 	svc_exit_thread(rqstp);
512 
513 	/* Release module */
514 	mutex_unlock(&nfsd_mutex);
515 	module_put_and_exit(0);
516 	return 0;
517 }
518 
519 static __be32 map_new_errors(u32 vers, __be32 nfserr)
520 {
521 	if (nfserr == nfserr_jukebox && vers == 2)
522 		return nfserr_dropit;
523 	if (nfserr == nfserr_wrongsec && vers < 4)
524 		return nfserr_acces;
525 	return nfserr;
526 }
527 
528 int
529 nfsd_dispatch(struct svc_rqst *rqstp, __be32 *statp)
530 {
531 	struct svc_procedure	*proc;
532 	kxdrproc_t		xdr;
533 	__be32			nfserr;
534 	__be32			*nfserrp;
535 
536 	dprintk("nfsd_dispatch: vers %d proc %d\n",
537 				rqstp->rq_vers, rqstp->rq_proc);
538 	proc = rqstp->rq_procinfo;
539 
540 	/* Check whether we have this call in the cache. */
541 	switch (nfsd_cache_lookup(rqstp, proc->pc_cachetype)) {
542 	case RC_INTR:
543 	case RC_DROPIT:
544 		return 0;
545 	case RC_REPLY:
546 		return 1;
547 	case RC_DOIT:;
548 		/* do it */
549 	}
550 
551 	/* Decode arguments */
552 	xdr = proc->pc_decode;
553 	if (xdr && !xdr(rqstp, (__be32*)rqstp->rq_arg.head[0].iov_base,
554 			rqstp->rq_argp)) {
555 		dprintk("nfsd: failed to decode arguments!\n");
556 		nfsd_cache_update(rqstp, RC_NOCACHE, NULL);
557 		*statp = rpc_garbage_args;
558 		return 1;
559 	}
560 
561 	/* need to grab the location to store the status, as
562 	 * nfsv4 does some encoding while processing
563 	 */
564 	nfserrp = rqstp->rq_res.head[0].iov_base
565 		+ rqstp->rq_res.head[0].iov_len;
566 	rqstp->rq_res.head[0].iov_len += sizeof(__be32);
567 
568 	/* Now call the procedure handler, and encode NFS status. */
569 	nfserr = proc->pc_func(rqstp, rqstp->rq_argp, rqstp->rq_resp);
570 	nfserr = map_new_errors(rqstp->rq_vers, nfserr);
571 	if (nfserr == nfserr_dropit) {
572 		dprintk("nfsd: Dropping request; may be revisited later\n");
573 		nfsd_cache_update(rqstp, RC_NOCACHE, NULL);
574 		return 0;
575 	}
576 
577 	if (rqstp->rq_proc != 0)
578 		*nfserrp++ = nfserr;
579 
580 	/* Encode result.
581 	 * For NFSv2, additional info is never returned in case of an error.
582 	 */
583 	if (!(nfserr && rqstp->rq_vers == 2)) {
584 		xdr = proc->pc_encode;
585 		if (xdr && !xdr(rqstp, nfserrp,
586 				rqstp->rq_resp)) {
587 			/* Failed to encode result. Release cache entry */
588 			dprintk("nfsd: failed to encode result!\n");
589 			nfsd_cache_update(rqstp, RC_NOCACHE, NULL);
590 			*statp = rpc_system_err;
591 			return 1;
592 		}
593 	}
594 
595 	/* Store reply in cache. */
596 	nfsd_cache_update(rqstp, proc->pc_cachetype, statp + 1);
597 	return 1;
598 }
599 
600 int nfsd_pool_stats_open(struct inode *inode, struct file *file)
601 {
602 	int ret;
603 	mutex_lock(&nfsd_mutex);
604 	if (nfsd_serv == NULL) {
605 		mutex_unlock(&nfsd_mutex);
606 		return -ENODEV;
607 	}
608 	/* bump up the psudo refcount while traversing */
609 	svc_get(nfsd_serv);
610 	ret = svc_pool_stats_open(nfsd_serv, file);
611 	mutex_unlock(&nfsd_mutex);
612 	return ret;
613 }
614 
615 int nfsd_pool_stats_release(struct inode *inode, struct file *file)
616 {
617 	int ret = seq_release(inode, file);
618 	mutex_lock(&nfsd_mutex);
619 	/* this function really, really should have been called svc_put() */
620 	svc_destroy(nfsd_serv);
621 	mutex_unlock(&nfsd_mutex);
622 	return ret;
623 }
624