xref: /linux/fs/nfs/client.c (revision af873fcecef567abf8a3468b06dd4e4aab46da6d)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* client.c: NFS client sharing and management code
3  *
4  * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
5  * Written by David Howells (dhowells@redhat.com)
6  */
7 
8 
9 #include <linux/module.h>
10 #include <linux/init.h>
11 #include <linux/sched.h>
12 #include <linux/time.h>
13 #include <linux/kernel.h>
14 #include <linux/mm.h>
15 #include <linux/string.h>
16 #include <linux/stat.h>
17 #include <linux/errno.h>
18 #include <linux/unistd.h>
19 #include <linux/sunrpc/addr.h>
20 #include <linux/sunrpc/clnt.h>
21 #include <linux/sunrpc/stats.h>
22 #include <linux/sunrpc/metrics.h>
23 #include <linux/sunrpc/xprtsock.h>
24 #include <linux/sunrpc/xprtrdma.h>
25 #include <linux/nfs_fs.h>
26 #include <linux/nfs_mount.h>
27 #include <linux/nfs4_mount.h>
28 #include <linux/lockd/bind.h>
29 #include <linux/seq_file.h>
30 #include <linux/mount.h>
31 #include <linux/vfs.h>
32 #include <linux/inet.h>
33 #include <linux/in6.h>
34 #include <linux/slab.h>
35 #include <linux/idr.h>
36 #include <net/ipv6.h>
37 #include <linux/nfs_xdr.h>
38 #include <linux/sunrpc/bc_xprt.h>
39 #include <linux/nsproxy.h>
40 #include <linux/pid_namespace.h>
41 
42 
43 #include "nfs4_fs.h"
44 #include "callback.h"
45 #include "delegation.h"
46 #include "iostat.h"
47 #include "internal.h"
48 #include "fscache.h"
49 #include "pnfs.h"
50 #include "nfs.h"
51 #include "netns.h"
52 
53 #define NFSDBG_FACILITY		NFSDBG_CLIENT
54 
55 static DECLARE_WAIT_QUEUE_HEAD(nfs_client_active_wq);
56 static DEFINE_SPINLOCK(nfs_version_lock);
57 static DEFINE_MUTEX(nfs_version_mutex);
58 static LIST_HEAD(nfs_versions);
59 
60 /*
61  * RPC cruft for NFS
62  */
63 static const struct rpc_version *nfs_version[5] = {
64 	[2] = NULL,
65 	[3] = NULL,
66 	[4] = NULL,
67 };
68 
69 const struct rpc_program nfs_program = {
70 	.name			= "nfs",
71 	.number			= NFS_PROGRAM,
72 	.nrvers			= ARRAY_SIZE(nfs_version),
73 	.version		= nfs_version,
74 	.stats			= &nfs_rpcstat,
75 	.pipe_dir_name		= NFS_PIPE_DIRNAME,
76 };
77 
78 struct rpc_stat nfs_rpcstat = {
79 	.program		= &nfs_program
80 };
81 
82 static struct nfs_subversion *find_nfs_version(unsigned int version)
83 {
84 	struct nfs_subversion *nfs;
85 	spin_lock(&nfs_version_lock);
86 
87 	list_for_each_entry(nfs, &nfs_versions, list) {
88 		if (nfs->rpc_ops->version == version) {
89 			spin_unlock(&nfs_version_lock);
90 			return nfs;
91 		}
92 	}
93 
94 	spin_unlock(&nfs_version_lock);
95 	return ERR_PTR(-EPROTONOSUPPORT);
96 }
97 
98 struct nfs_subversion *get_nfs_version(unsigned int version)
99 {
100 	struct nfs_subversion *nfs = find_nfs_version(version);
101 
102 	if (IS_ERR(nfs)) {
103 		mutex_lock(&nfs_version_mutex);
104 		request_module("nfsv%d", version);
105 		nfs = find_nfs_version(version);
106 		mutex_unlock(&nfs_version_mutex);
107 	}
108 
109 	if (!IS_ERR(nfs) && !try_module_get(nfs->owner))
110 		return ERR_PTR(-EAGAIN);
111 	return nfs;
112 }
113 
114 void put_nfs_version(struct nfs_subversion *nfs)
115 {
116 	module_put(nfs->owner);
117 }
118 
119 void register_nfs_version(struct nfs_subversion *nfs)
120 {
121 	spin_lock(&nfs_version_lock);
122 
123 	list_add(&nfs->list, &nfs_versions);
124 	nfs_version[nfs->rpc_ops->version] = nfs->rpc_vers;
125 
126 	spin_unlock(&nfs_version_lock);
127 }
128 EXPORT_SYMBOL_GPL(register_nfs_version);
129 
130 void unregister_nfs_version(struct nfs_subversion *nfs)
131 {
132 	spin_lock(&nfs_version_lock);
133 
134 	nfs_version[nfs->rpc_ops->version] = NULL;
135 	list_del(&nfs->list);
136 
137 	spin_unlock(&nfs_version_lock);
138 }
139 EXPORT_SYMBOL_GPL(unregister_nfs_version);
140 
141 /*
142  * Allocate a shared client record
143  *
144  * Since these are allocated/deallocated very rarely, we don't
145  * bother putting them in a slab cache...
146  */
147 struct nfs_client *nfs_alloc_client(const struct nfs_client_initdata *cl_init)
148 {
149 	struct nfs_client *clp;
150 	int err = -ENOMEM;
151 
152 	if ((clp = kzalloc(sizeof(*clp), GFP_KERNEL)) == NULL)
153 		goto error_0;
154 
155 	clp->cl_nfs_mod = cl_init->nfs_mod;
156 	if (!try_module_get(clp->cl_nfs_mod->owner))
157 		goto error_dealloc;
158 
159 	clp->rpc_ops = clp->cl_nfs_mod->rpc_ops;
160 
161 	refcount_set(&clp->cl_count, 1);
162 	clp->cl_cons_state = NFS_CS_INITING;
163 
164 	memcpy(&clp->cl_addr, cl_init->addr, cl_init->addrlen);
165 	clp->cl_addrlen = cl_init->addrlen;
166 
167 	if (cl_init->hostname) {
168 		err = -ENOMEM;
169 		clp->cl_hostname = kstrdup(cl_init->hostname, GFP_KERNEL);
170 		if (!clp->cl_hostname)
171 			goto error_cleanup;
172 	}
173 
174 	INIT_LIST_HEAD(&clp->cl_superblocks);
175 	clp->cl_rpcclient = ERR_PTR(-EINVAL);
176 
177 	clp->cl_proto = cl_init->proto;
178 	clp->cl_net = get_net(cl_init->net);
179 
180 	clp->cl_principal = "*";
181 	nfs_fscache_get_client_cookie(clp);
182 
183 	return clp;
184 
185 error_cleanup:
186 	put_nfs_version(clp->cl_nfs_mod);
187 error_dealloc:
188 	kfree(clp);
189 error_0:
190 	return ERR_PTR(err);
191 }
192 EXPORT_SYMBOL_GPL(nfs_alloc_client);
193 
194 #if IS_ENABLED(CONFIG_NFS_V4)
195 void nfs_cleanup_cb_ident_idr(struct net *net)
196 {
197 	struct nfs_net *nn = net_generic(net, nfs_net_id);
198 
199 	idr_destroy(&nn->cb_ident_idr);
200 }
201 
202 /* nfs_client_lock held */
203 static void nfs_cb_idr_remove_locked(struct nfs_client *clp)
204 {
205 	struct nfs_net *nn = net_generic(clp->cl_net, nfs_net_id);
206 
207 	if (clp->cl_cb_ident)
208 		idr_remove(&nn->cb_ident_idr, clp->cl_cb_ident);
209 }
210 
211 static void pnfs_init_server(struct nfs_server *server)
212 {
213 	rpc_init_wait_queue(&server->roc_rpcwaitq, "pNFS ROC");
214 }
215 
216 #else
217 void nfs_cleanup_cb_ident_idr(struct net *net)
218 {
219 }
220 
221 static void nfs_cb_idr_remove_locked(struct nfs_client *clp)
222 {
223 }
224 
225 static void pnfs_init_server(struct nfs_server *server)
226 {
227 }
228 
229 #endif /* CONFIG_NFS_V4 */
230 
231 /*
232  * Destroy a shared client record
233  */
234 void nfs_free_client(struct nfs_client *clp)
235 {
236 	nfs_fscache_release_client_cookie(clp);
237 
238 	/* -EIO all pending I/O */
239 	if (!IS_ERR(clp->cl_rpcclient))
240 		rpc_shutdown_client(clp->cl_rpcclient);
241 
242 	put_net(clp->cl_net);
243 	put_nfs_version(clp->cl_nfs_mod);
244 	kfree(clp->cl_hostname);
245 	kfree(clp->cl_acceptor);
246 	kfree(clp);
247 }
248 EXPORT_SYMBOL_GPL(nfs_free_client);
249 
250 /*
251  * Release a reference to a shared client record
252  */
253 void nfs_put_client(struct nfs_client *clp)
254 {
255 	struct nfs_net *nn;
256 
257 	if (!clp)
258 		return;
259 
260 	nn = net_generic(clp->cl_net, nfs_net_id);
261 
262 	if (refcount_dec_and_lock(&clp->cl_count, &nn->nfs_client_lock)) {
263 		list_del(&clp->cl_share_link);
264 		nfs_cb_idr_remove_locked(clp);
265 		spin_unlock(&nn->nfs_client_lock);
266 
267 		WARN_ON_ONCE(!list_empty(&clp->cl_superblocks));
268 
269 		clp->rpc_ops->free_client(clp);
270 	}
271 }
272 EXPORT_SYMBOL_GPL(nfs_put_client);
273 
274 /*
275  * Find an nfs_client on the list that matches the initialisation data
276  * that is supplied.
277  */
278 static struct nfs_client *nfs_match_client(const struct nfs_client_initdata *data)
279 {
280 	struct nfs_client *clp;
281 	const struct sockaddr *sap = data->addr;
282 	struct nfs_net *nn = net_generic(data->net, nfs_net_id);
283 	int error;
284 
285 again:
286 	list_for_each_entry(clp, &nn->nfs_client_list, cl_share_link) {
287 	        const struct sockaddr *clap = (struct sockaddr *)&clp->cl_addr;
288 		/* Don't match clients that failed to initialise properly */
289 		if (clp->cl_cons_state < 0)
290 			continue;
291 
292 		/* If a client is still initializing then we need to wait */
293 		if (clp->cl_cons_state > NFS_CS_READY) {
294 			refcount_inc(&clp->cl_count);
295 			spin_unlock(&nn->nfs_client_lock);
296 			error = nfs_wait_client_init_complete(clp);
297 			nfs_put_client(clp);
298 			spin_lock(&nn->nfs_client_lock);
299 			if (error < 0)
300 				return ERR_PTR(error);
301 			goto again;
302 		}
303 
304 		/* Different NFS versions cannot share the same nfs_client */
305 		if (clp->rpc_ops != data->nfs_mod->rpc_ops)
306 			continue;
307 
308 		if (clp->cl_proto != data->proto)
309 			continue;
310 		/* Match nfsv4 minorversion */
311 		if (clp->cl_minorversion != data->minorversion)
312 			continue;
313 		/* Match the full socket address */
314 		if (!rpc_cmp_addr_port(sap, clap))
315 			/* Match all xprt_switch full socket addresses */
316 			if (IS_ERR(clp->cl_rpcclient) ||
317                             !rpc_clnt_xprt_switch_has_addr(clp->cl_rpcclient,
318 							   sap))
319 				continue;
320 
321 		refcount_inc(&clp->cl_count);
322 		return clp;
323 	}
324 	return NULL;
325 }
326 
327 /*
328  * Return true if @clp is done initializing, false if still working on it.
329  *
330  * Use nfs_client_init_status to check if it was successful.
331  */
332 bool nfs_client_init_is_complete(const struct nfs_client *clp)
333 {
334 	return clp->cl_cons_state <= NFS_CS_READY;
335 }
336 EXPORT_SYMBOL_GPL(nfs_client_init_is_complete);
337 
338 /*
339  * Return 0 if @clp was successfully initialized, -errno otherwise.
340  *
341  * This must be called *after* nfs_client_init_is_complete() returns true,
342  * otherwise it will pop WARN_ON_ONCE and return -EINVAL
343  */
344 int nfs_client_init_status(const struct nfs_client *clp)
345 {
346 	/* called without checking nfs_client_init_is_complete */
347 	if (clp->cl_cons_state > NFS_CS_READY) {
348 		WARN_ON_ONCE(1);
349 		return -EINVAL;
350 	}
351 	return clp->cl_cons_state;
352 }
353 EXPORT_SYMBOL_GPL(nfs_client_init_status);
354 
355 int nfs_wait_client_init_complete(const struct nfs_client *clp)
356 {
357 	return wait_event_killable(nfs_client_active_wq,
358 			nfs_client_init_is_complete(clp));
359 }
360 EXPORT_SYMBOL_GPL(nfs_wait_client_init_complete);
361 
362 /*
363  * Found an existing client.  Make sure it's ready before returning.
364  */
365 static struct nfs_client *
366 nfs_found_client(const struct nfs_client_initdata *cl_init,
367 		 struct nfs_client *clp)
368 {
369 	int error;
370 
371 	error = nfs_wait_client_init_complete(clp);
372 	if (error < 0) {
373 		nfs_put_client(clp);
374 		return ERR_PTR(-ERESTARTSYS);
375 	}
376 
377 	if (clp->cl_cons_state < NFS_CS_READY) {
378 		error = clp->cl_cons_state;
379 		nfs_put_client(clp);
380 		return ERR_PTR(error);
381 	}
382 
383 	smp_rmb();
384 	return clp;
385 }
386 
387 /*
388  * Look up a client by IP address and protocol version
389  * - creates a new record if one doesn't yet exist
390  */
391 struct nfs_client *nfs_get_client(const struct nfs_client_initdata *cl_init)
392 {
393 	struct nfs_client *clp, *new = NULL;
394 	struct nfs_net *nn = net_generic(cl_init->net, nfs_net_id);
395 	const struct nfs_rpc_ops *rpc_ops = cl_init->nfs_mod->rpc_ops;
396 
397 	if (cl_init->hostname == NULL) {
398 		WARN_ON(1);
399 		return NULL;
400 	}
401 
402 	/* see if the client already exists */
403 	do {
404 		spin_lock(&nn->nfs_client_lock);
405 
406 		clp = nfs_match_client(cl_init);
407 		if (clp) {
408 			spin_unlock(&nn->nfs_client_lock);
409 			if (IS_ERR(clp))
410 				return clp;
411 			if (new)
412 				new->rpc_ops->free_client(new);
413 			return nfs_found_client(cl_init, clp);
414 		}
415 		if (new) {
416 			list_add_tail(&new->cl_share_link,
417 					&nn->nfs_client_list);
418 			spin_unlock(&nn->nfs_client_lock);
419 			new->cl_flags = cl_init->init_flags;
420 			return rpc_ops->init_client(new, cl_init);
421 		}
422 
423 		spin_unlock(&nn->nfs_client_lock);
424 
425 		new = rpc_ops->alloc_client(cl_init);
426 	} while (!IS_ERR(new));
427 
428 	return new;
429 }
430 EXPORT_SYMBOL_GPL(nfs_get_client);
431 
432 /*
433  * Mark a server as ready or failed
434  */
435 void nfs_mark_client_ready(struct nfs_client *clp, int state)
436 {
437 	smp_wmb();
438 	clp->cl_cons_state = state;
439 	wake_up_all(&nfs_client_active_wq);
440 }
441 EXPORT_SYMBOL_GPL(nfs_mark_client_ready);
442 
443 /*
444  * Initialise the timeout values for a connection
445  */
446 void nfs_init_timeout_values(struct rpc_timeout *to, int proto,
447 				    int timeo, int retrans)
448 {
449 	to->to_initval = timeo * HZ / 10;
450 	to->to_retries = retrans;
451 
452 	switch (proto) {
453 	case XPRT_TRANSPORT_TCP:
454 	case XPRT_TRANSPORT_RDMA:
455 		if (retrans == NFS_UNSPEC_RETRANS)
456 			to->to_retries = NFS_DEF_TCP_RETRANS;
457 		if (timeo == NFS_UNSPEC_TIMEO || to->to_initval == 0)
458 			to->to_initval = NFS_DEF_TCP_TIMEO * HZ / 10;
459 		if (to->to_initval > NFS_MAX_TCP_TIMEOUT)
460 			to->to_initval = NFS_MAX_TCP_TIMEOUT;
461 		to->to_increment = to->to_initval;
462 		to->to_maxval = to->to_initval + (to->to_increment * to->to_retries);
463 		if (to->to_maxval > NFS_MAX_TCP_TIMEOUT)
464 			to->to_maxval = NFS_MAX_TCP_TIMEOUT;
465 		if (to->to_maxval < to->to_initval)
466 			to->to_maxval = to->to_initval;
467 		to->to_exponential = 0;
468 		break;
469 	case XPRT_TRANSPORT_UDP:
470 		if (retrans == NFS_UNSPEC_RETRANS)
471 			to->to_retries = NFS_DEF_UDP_RETRANS;
472 		if (timeo == NFS_UNSPEC_TIMEO || to->to_initval == 0)
473 			to->to_initval = NFS_DEF_UDP_TIMEO * HZ / 10;
474 		if (to->to_initval > NFS_MAX_UDP_TIMEOUT)
475 			to->to_initval = NFS_MAX_UDP_TIMEOUT;
476 		to->to_maxval = NFS_MAX_UDP_TIMEOUT;
477 		to->to_exponential = 1;
478 		break;
479 	default:
480 		BUG();
481 	}
482 }
483 EXPORT_SYMBOL_GPL(nfs_init_timeout_values);
484 
485 /*
486  * Create an RPC client handle
487  */
488 int nfs_create_rpc_client(struct nfs_client *clp,
489 			  const struct nfs_client_initdata *cl_init,
490 			  rpc_authflavor_t flavor)
491 {
492 	struct rpc_clnt		*clnt = NULL;
493 	struct rpc_create_args args = {
494 		.net		= clp->cl_net,
495 		.protocol	= clp->cl_proto,
496 		.address	= (struct sockaddr *)&clp->cl_addr,
497 		.addrsize	= clp->cl_addrlen,
498 		.timeout	= cl_init->timeparms,
499 		.servername	= clp->cl_hostname,
500 		.nodename	= cl_init->nodename,
501 		.program	= &nfs_program,
502 		.version	= clp->rpc_ops->version,
503 		.authflavor	= flavor,
504 		.cred		= cl_init->cred,
505 	};
506 
507 	if (test_bit(NFS_CS_DISCRTRY, &clp->cl_flags))
508 		args.flags |= RPC_CLNT_CREATE_DISCRTRY;
509 	if (test_bit(NFS_CS_NO_RETRANS_TIMEOUT, &clp->cl_flags))
510 		args.flags |= RPC_CLNT_CREATE_NO_RETRANS_TIMEOUT;
511 	if (test_bit(NFS_CS_NORESVPORT, &clp->cl_flags))
512 		args.flags |= RPC_CLNT_CREATE_NONPRIVPORT;
513 	if (test_bit(NFS_CS_INFINITE_SLOTS, &clp->cl_flags))
514 		args.flags |= RPC_CLNT_CREATE_INFINITE_SLOTS;
515 
516 	if (!IS_ERR(clp->cl_rpcclient))
517 		return 0;
518 
519 	clnt = rpc_create(&args);
520 	if (IS_ERR(clnt)) {
521 		dprintk("%s: cannot create RPC client. Error = %ld\n",
522 				__func__, PTR_ERR(clnt));
523 		return PTR_ERR(clnt);
524 	}
525 
526 	clnt->cl_principal = clp->cl_principal;
527 	clp->cl_rpcclient = clnt;
528 	return 0;
529 }
530 EXPORT_SYMBOL_GPL(nfs_create_rpc_client);
531 
532 /*
533  * Version 2 or 3 client destruction
534  */
535 static void nfs_destroy_server(struct nfs_server *server)
536 {
537 	if (server->nlm_host)
538 		nlmclnt_done(server->nlm_host);
539 }
540 
541 /*
542  * Version 2 or 3 lockd setup
543  */
544 static int nfs_start_lockd(struct nfs_server *server)
545 {
546 	struct nlm_host *host;
547 	struct nfs_client *clp = server->nfs_client;
548 	struct nlmclnt_initdata nlm_init = {
549 		.hostname	= clp->cl_hostname,
550 		.address	= (struct sockaddr *)&clp->cl_addr,
551 		.addrlen	= clp->cl_addrlen,
552 		.nfs_version	= clp->rpc_ops->version,
553 		.noresvport	= server->flags & NFS_MOUNT_NORESVPORT ?
554 					1 : 0,
555 		.net		= clp->cl_net,
556 		.nlmclnt_ops 	= clp->cl_nfs_mod->rpc_ops->nlmclnt_ops,
557 		.cred		= current_cred(),
558 	};
559 
560 	if (nlm_init.nfs_version > 3)
561 		return 0;
562 	if ((server->flags & NFS_MOUNT_LOCAL_FLOCK) &&
563 			(server->flags & NFS_MOUNT_LOCAL_FCNTL))
564 		return 0;
565 
566 	switch (clp->cl_proto) {
567 		default:
568 			nlm_init.protocol = IPPROTO_TCP;
569 			break;
570 		case XPRT_TRANSPORT_UDP:
571 			nlm_init.protocol = IPPROTO_UDP;
572 	}
573 
574 	host = nlmclnt_init(&nlm_init);
575 	if (IS_ERR(host))
576 		return PTR_ERR(host);
577 
578 	server->nlm_host = host;
579 	server->destroy = nfs_destroy_server;
580 	return 0;
581 }
582 
583 /*
584  * Create a general RPC client
585  */
586 int nfs_init_server_rpcclient(struct nfs_server *server,
587 		const struct rpc_timeout *timeo,
588 		rpc_authflavor_t pseudoflavour)
589 {
590 	struct nfs_client *clp = server->nfs_client;
591 
592 	server->client = rpc_clone_client_set_auth(clp->cl_rpcclient,
593 							pseudoflavour);
594 	if (IS_ERR(server->client)) {
595 		dprintk("%s: couldn't create rpc_client!\n", __func__);
596 		return PTR_ERR(server->client);
597 	}
598 
599 	memcpy(&server->client->cl_timeout_default,
600 			timeo,
601 			sizeof(server->client->cl_timeout_default));
602 	server->client->cl_timeout = &server->client->cl_timeout_default;
603 	server->client->cl_softrtry = 0;
604 	if (server->flags & NFS_MOUNT_SOFTERR)
605 		server->client->cl_softerr = 1;
606 	if (server->flags & NFS_MOUNT_SOFT)
607 		server->client->cl_softrtry = 1;
608 
609 	return 0;
610 }
611 EXPORT_SYMBOL_GPL(nfs_init_server_rpcclient);
612 
613 /**
614  * nfs_init_client - Initialise an NFS2 or NFS3 client
615  *
616  * @clp: nfs_client to initialise
617  * @cl_init: Initialisation parameters
618  *
619  * Returns pointer to an NFS client, or an ERR_PTR value.
620  */
621 struct nfs_client *nfs_init_client(struct nfs_client *clp,
622 				   const struct nfs_client_initdata *cl_init)
623 {
624 	int error;
625 
626 	/* the client is already initialised */
627 	if (clp->cl_cons_state == NFS_CS_READY)
628 		return clp;
629 
630 	/*
631 	 * Create a client RPC handle for doing FSSTAT with UNIX auth only
632 	 * - RFC 2623, sec 2.3.2
633 	 */
634 	error = nfs_create_rpc_client(clp, cl_init, RPC_AUTH_UNIX);
635 	nfs_mark_client_ready(clp, error == 0 ? NFS_CS_READY : error);
636 	if (error < 0) {
637 		nfs_put_client(clp);
638 		clp = ERR_PTR(error);
639 	}
640 	return clp;
641 }
642 EXPORT_SYMBOL_GPL(nfs_init_client);
643 
644 /*
645  * Create a version 2 or 3 client
646  */
647 static int nfs_init_server(struct nfs_server *server,
648 			   const struct nfs_parsed_mount_data *data,
649 			   struct nfs_subversion *nfs_mod)
650 {
651 	struct rpc_timeout timeparms;
652 	struct nfs_client_initdata cl_init = {
653 		.hostname = data->nfs_server.hostname,
654 		.addr = (const struct sockaddr *)&data->nfs_server.address,
655 		.addrlen = data->nfs_server.addrlen,
656 		.nfs_mod = nfs_mod,
657 		.proto = data->nfs_server.protocol,
658 		.net = data->net,
659 		.timeparms = &timeparms,
660 		.cred = server->cred,
661 	};
662 	struct nfs_client *clp;
663 	int error;
664 
665 	nfs_init_timeout_values(&timeparms, data->nfs_server.protocol,
666 			data->timeo, data->retrans);
667 	if (data->flags & NFS_MOUNT_NORESVPORT)
668 		set_bit(NFS_CS_NORESVPORT, &cl_init.init_flags);
669 
670 	/* Allocate or find a client reference we can use */
671 	clp = nfs_get_client(&cl_init);
672 	if (IS_ERR(clp))
673 		return PTR_ERR(clp);
674 
675 	server->nfs_client = clp;
676 
677 	/* Initialise the client representation from the mount data */
678 	server->flags = data->flags;
679 	server->options = data->options;
680 	server->caps |= NFS_CAP_HARDLINKS|NFS_CAP_SYMLINKS|NFS_CAP_FILEID|
681 		NFS_CAP_MODE|NFS_CAP_NLINK|NFS_CAP_OWNER|NFS_CAP_OWNER_GROUP|
682 		NFS_CAP_ATIME|NFS_CAP_CTIME|NFS_CAP_MTIME;
683 
684 	if (data->rsize)
685 		server->rsize = nfs_block_size(data->rsize, NULL);
686 	if (data->wsize)
687 		server->wsize = nfs_block_size(data->wsize, NULL);
688 
689 	server->acregmin = data->acregmin * HZ;
690 	server->acregmax = data->acregmax * HZ;
691 	server->acdirmin = data->acdirmin * HZ;
692 	server->acdirmax = data->acdirmax * HZ;
693 
694 	/* Start lockd here, before we might error out */
695 	error = nfs_start_lockd(server);
696 	if (error < 0)
697 		goto error;
698 
699 	server->port = data->nfs_server.port;
700 	server->auth_info = data->auth_info;
701 
702 	error = nfs_init_server_rpcclient(server, &timeparms,
703 					  data->selected_flavor);
704 	if (error < 0)
705 		goto error;
706 
707 	/* Preserve the values of mount_server-related mount options */
708 	if (data->mount_server.addrlen) {
709 		memcpy(&server->mountd_address, &data->mount_server.address,
710 			data->mount_server.addrlen);
711 		server->mountd_addrlen = data->mount_server.addrlen;
712 	}
713 	server->mountd_version = data->mount_server.version;
714 	server->mountd_port = data->mount_server.port;
715 	server->mountd_protocol = data->mount_server.protocol;
716 
717 	server->namelen  = data->namlen;
718 	return 0;
719 
720 error:
721 	server->nfs_client = NULL;
722 	nfs_put_client(clp);
723 	return error;
724 }
725 
726 /*
727  * Load up the server record from information gained in an fsinfo record
728  */
729 static void nfs_server_set_fsinfo(struct nfs_server *server,
730 				  struct nfs_fsinfo *fsinfo)
731 {
732 	unsigned long max_rpc_payload;
733 
734 	/* Work out a lot of parameters */
735 	if (server->rsize == 0)
736 		server->rsize = nfs_block_size(fsinfo->rtpref, NULL);
737 	if (server->wsize == 0)
738 		server->wsize = nfs_block_size(fsinfo->wtpref, NULL);
739 
740 	if (fsinfo->rtmax >= 512 && server->rsize > fsinfo->rtmax)
741 		server->rsize = nfs_block_size(fsinfo->rtmax, NULL);
742 	if (fsinfo->wtmax >= 512 && server->wsize > fsinfo->wtmax)
743 		server->wsize = nfs_block_size(fsinfo->wtmax, NULL);
744 
745 	max_rpc_payload = nfs_block_size(rpc_max_payload(server->client), NULL);
746 	if (server->rsize > max_rpc_payload)
747 		server->rsize = max_rpc_payload;
748 	if (server->rsize > NFS_MAX_FILE_IO_SIZE)
749 		server->rsize = NFS_MAX_FILE_IO_SIZE;
750 	server->rpages = (server->rsize + PAGE_SIZE - 1) >> PAGE_SHIFT;
751 
752 	if (server->wsize > max_rpc_payload)
753 		server->wsize = max_rpc_payload;
754 	if (server->wsize > NFS_MAX_FILE_IO_SIZE)
755 		server->wsize = NFS_MAX_FILE_IO_SIZE;
756 	server->wpages = (server->wsize + PAGE_SIZE - 1) >> PAGE_SHIFT;
757 
758 	server->wtmult = nfs_block_bits(fsinfo->wtmult, NULL);
759 
760 	server->dtsize = nfs_block_size(fsinfo->dtpref, NULL);
761 	if (server->dtsize > PAGE_SIZE * NFS_MAX_READDIR_PAGES)
762 		server->dtsize = PAGE_SIZE * NFS_MAX_READDIR_PAGES;
763 	if (server->dtsize > server->rsize)
764 		server->dtsize = server->rsize;
765 
766 	if (server->flags & NFS_MOUNT_NOAC) {
767 		server->acregmin = server->acregmax = 0;
768 		server->acdirmin = server->acdirmax = 0;
769 	}
770 
771 	server->maxfilesize = fsinfo->maxfilesize;
772 
773 	server->time_delta = fsinfo->time_delta;
774 
775 	server->clone_blksize = fsinfo->clone_blksize;
776 	/* We're airborne Set socket buffersize */
777 	rpc_setbufsize(server->client, server->wsize + 100, server->rsize + 100);
778 }
779 
780 /*
781  * Probe filesystem information, including the FSID on v2/v3
782  */
783 int nfs_probe_fsinfo(struct nfs_server *server, struct nfs_fh *mntfh, struct nfs_fattr *fattr)
784 {
785 	struct nfs_fsinfo fsinfo;
786 	struct nfs_client *clp = server->nfs_client;
787 	int error;
788 
789 	if (clp->rpc_ops->set_capabilities != NULL) {
790 		error = clp->rpc_ops->set_capabilities(server, mntfh);
791 		if (error < 0)
792 			return error;
793 	}
794 
795 	fsinfo.fattr = fattr;
796 	fsinfo.nlayouttypes = 0;
797 	memset(fsinfo.layouttype, 0, sizeof(fsinfo.layouttype));
798 	error = clp->rpc_ops->fsinfo(server, mntfh, &fsinfo);
799 	if (error < 0)
800 		return error;
801 
802 	nfs_server_set_fsinfo(server, &fsinfo);
803 
804 	/* Get some general file system info */
805 	if (server->namelen == 0) {
806 		struct nfs_pathconf pathinfo;
807 
808 		pathinfo.fattr = fattr;
809 		nfs_fattr_init(fattr);
810 
811 		if (clp->rpc_ops->pathconf(server, mntfh, &pathinfo) >= 0)
812 			server->namelen = pathinfo.max_namelen;
813 	}
814 
815 	return 0;
816 }
817 EXPORT_SYMBOL_GPL(nfs_probe_fsinfo);
818 
819 /*
820  * Copy useful information when duplicating a server record
821  */
822 void nfs_server_copy_userdata(struct nfs_server *target, struct nfs_server *source)
823 {
824 	target->flags = source->flags;
825 	target->rsize = source->rsize;
826 	target->wsize = source->wsize;
827 	target->acregmin = source->acregmin;
828 	target->acregmax = source->acregmax;
829 	target->acdirmin = source->acdirmin;
830 	target->acdirmax = source->acdirmax;
831 	target->caps = source->caps;
832 	target->options = source->options;
833 	target->auth_info = source->auth_info;
834 	target->port = source->port;
835 }
836 EXPORT_SYMBOL_GPL(nfs_server_copy_userdata);
837 
838 void nfs_server_insert_lists(struct nfs_server *server)
839 {
840 	struct nfs_client *clp = server->nfs_client;
841 	struct nfs_net *nn = net_generic(clp->cl_net, nfs_net_id);
842 
843 	spin_lock(&nn->nfs_client_lock);
844 	list_add_tail_rcu(&server->client_link, &clp->cl_superblocks);
845 	list_add_tail(&server->master_link, &nn->nfs_volume_list);
846 	clear_bit(NFS_CS_STOP_RENEW, &clp->cl_res_state);
847 	spin_unlock(&nn->nfs_client_lock);
848 
849 }
850 EXPORT_SYMBOL_GPL(nfs_server_insert_lists);
851 
852 void nfs_server_remove_lists(struct nfs_server *server)
853 {
854 	struct nfs_client *clp = server->nfs_client;
855 	struct nfs_net *nn;
856 
857 	if (clp == NULL)
858 		return;
859 	nn = net_generic(clp->cl_net, nfs_net_id);
860 	spin_lock(&nn->nfs_client_lock);
861 	list_del_rcu(&server->client_link);
862 	if (list_empty(&clp->cl_superblocks))
863 		set_bit(NFS_CS_STOP_RENEW, &clp->cl_res_state);
864 	list_del(&server->master_link);
865 	spin_unlock(&nn->nfs_client_lock);
866 
867 	synchronize_rcu();
868 }
869 EXPORT_SYMBOL_GPL(nfs_server_remove_lists);
870 
871 /*
872  * Allocate and initialise a server record
873  */
874 struct nfs_server *nfs_alloc_server(void)
875 {
876 	struct nfs_server *server;
877 
878 	server = kzalloc(sizeof(struct nfs_server), GFP_KERNEL);
879 	if (!server)
880 		return NULL;
881 
882 	server->client = server->client_acl = ERR_PTR(-EINVAL);
883 
884 	/* Zero out the NFS state stuff */
885 	INIT_LIST_HEAD(&server->client_link);
886 	INIT_LIST_HEAD(&server->master_link);
887 	INIT_LIST_HEAD(&server->delegations);
888 	INIT_LIST_HEAD(&server->layouts);
889 	INIT_LIST_HEAD(&server->state_owners_lru);
890 	INIT_LIST_HEAD(&server->ss_copies);
891 
892 	atomic_set(&server->active, 0);
893 
894 	server->io_stats = nfs_alloc_iostats();
895 	if (!server->io_stats) {
896 		kfree(server);
897 		return NULL;
898 	}
899 
900 	ida_init(&server->openowner_id);
901 	ida_init(&server->lockowner_id);
902 	pnfs_init_server(server);
903 	rpc_init_wait_queue(&server->uoc_rpcwaitq, "NFS UOC");
904 
905 	return server;
906 }
907 EXPORT_SYMBOL_GPL(nfs_alloc_server);
908 
909 /*
910  * Free up a server record
911  */
912 void nfs_free_server(struct nfs_server *server)
913 {
914 	nfs_server_remove_lists(server);
915 
916 	if (server->destroy != NULL)
917 		server->destroy(server);
918 
919 	if (!IS_ERR(server->client_acl))
920 		rpc_shutdown_client(server->client_acl);
921 	if (!IS_ERR(server->client))
922 		rpc_shutdown_client(server->client);
923 
924 	nfs_put_client(server->nfs_client);
925 
926 	ida_destroy(&server->lockowner_id);
927 	ida_destroy(&server->openowner_id);
928 	nfs_free_iostats(server->io_stats);
929 	put_cred(server->cred);
930 	kfree(server);
931 	nfs_release_automount_timer();
932 }
933 EXPORT_SYMBOL_GPL(nfs_free_server);
934 
935 /*
936  * Create a version 2 or 3 volume record
937  * - keyed on server and FSID
938  */
939 struct nfs_server *nfs_create_server(struct nfs_mount_info *mount_info,
940 				     struct nfs_subversion *nfs_mod)
941 {
942 	struct nfs_server *server;
943 	struct nfs_fattr *fattr;
944 	int error;
945 
946 	server = nfs_alloc_server();
947 	if (!server)
948 		return ERR_PTR(-ENOMEM);
949 
950 	server->cred = get_cred(current_cred());
951 
952 	error = -ENOMEM;
953 	fattr = nfs_alloc_fattr();
954 	if (fattr == NULL)
955 		goto error;
956 
957 	/* Get a client representation */
958 	error = nfs_init_server(server, mount_info->parsed, nfs_mod);
959 	if (error < 0)
960 		goto error;
961 
962 	/* Probe the root fh to retrieve its FSID */
963 	error = nfs_probe_fsinfo(server, mount_info->mntfh, fattr);
964 	if (error < 0)
965 		goto error;
966 	if (server->nfs_client->rpc_ops->version == 3) {
967 		if (server->namelen == 0 || server->namelen > NFS3_MAXNAMLEN)
968 			server->namelen = NFS3_MAXNAMLEN;
969 		if (!(mount_info->parsed->flags & NFS_MOUNT_NORDIRPLUS))
970 			server->caps |= NFS_CAP_READDIRPLUS;
971 	} else {
972 		if (server->namelen == 0 || server->namelen > NFS2_MAXNAMLEN)
973 			server->namelen = NFS2_MAXNAMLEN;
974 	}
975 
976 	if (!(fattr->valid & NFS_ATTR_FATTR)) {
977 		error = nfs_mod->rpc_ops->getattr(server, mount_info->mntfh,
978 				fattr, NULL, NULL);
979 		if (error < 0) {
980 			dprintk("nfs_create_server: getattr error = %d\n", -error);
981 			goto error;
982 		}
983 	}
984 	memcpy(&server->fsid, &fattr->fsid, sizeof(server->fsid));
985 
986 	dprintk("Server FSID: %llx:%llx\n",
987 		(unsigned long long) server->fsid.major,
988 		(unsigned long long) server->fsid.minor);
989 
990 	nfs_server_insert_lists(server);
991 	server->mount_time = jiffies;
992 	nfs_free_fattr(fattr);
993 	return server;
994 
995 error:
996 	nfs_free_fattr(fattr);
997 	nfs_free_server(server);
998 	return ERR_PTR(error);
999 }
1000 EXPORT_SYMBOL_GPL(nfs_create_server);
1001 
1002 /*
1003  * Clone an NFS2, NFS3 or NFS4 server record
1004  */
1005 struct nfs_server *nfs_clone_server(struct nfs_server *source,
1006 				    struct nfs_fh *fh,
1007 				    struct nfs_fattr *fattr,
1008 				    rpc_authflavor_t flavor)
1009 {
1010 	struct nfs_server *server;
1011 	struct nfs_fattr *fattr_fsinfo;
1012 	int error;
1013 
1014 	server = nfs_alloc_server();
1015 	if (!server)
1016 		return ERR_PTR(-ENOMEM);
1017 
1018 	server->cred = get_cred(source->cred);
1019 
1020 	error = -ENOMEM;
1021 	fattr_fsinfo = nfs_alloc_fattr();
1022 	if (fattr_fsinfo == NULL)
1023 		goto out_free_server;
1024 
1025 	/* Copy data from the source */
1026 	server->nfs_client = source->nfs_client;
1027 	server->destroy = source->destroy;
1028 	refcount_inc(&server->nfs_client->cl_count);
1029 	nfs_server_copy_userdata(server, source);
1030 
1031 	server->fsid = fattr->fsid;
1032 
1033 	error = nfs_init_server_rpcclient(server,
1034 			source->client->cl_timeout,
1035 			flavor);
1036 	if (error < 0)
1037 		goto out_free_server;
1038 
1039 	/* probe the filesystem info for this server filesystem */
1040 	error = nfs_probe_fsinfo(server, fh, fattr_fsinfo);
1041 	if (error < 0)
1042 		goto out_free_server;
1043 
1044 	if (server->namelen == 0 || server->namelen > NFS4_MAXNAMLEN)
1045 		server->namelen = NFS4_MAXNAMLEN;
1046 
1047 	error = nfs_start_lockd(server);
1048 	if (error < 0)
1049 		goto out_free_server;
1050 
1051 	nfs_server_insert_lists(server);
1052 	server->mount_time = jiffies;
1053 
1054 	nfs_free_fattr(fattr_fsinfo);
1055 	return server;
1056 
1057 out_free_server:
1058 	nfs_free_fattr(fattr_fsinfo);
1059 	nfs_free_server(server);
1060 	return ERR_PTR(error);
1061 }
1062 EXPORT_SYMBOL_GPL(nfs_clone_server);
1063 
1064 void nfs_clients_init(struct net *net)
1065 {
1066 	struct nfs_net *nn = net_generic(net, nfs_net_id);
1067 
1068 	INIT_LIST_HEAD(&nn->nfs_client_list);
1069 	INIT_LIST_HEAD(&nn->nfs_volume_list);
1070 #if IS_ENABLED(CONFIG_NFS_V4)
1071 	idr_init(&nn->cb_ident_idr);
1072 #endif
1073 	spin_lock_init(&nn->nfs_client_lock);
1074 	nn->boot_time = ktime_get_real();
1075 }
1076 
1077 #ifdef CONFIG_PROC_FS
1078 static void *nfs_server_list_start(struct seq_file *p, loff_t *pos);
1079 static void *nfs_server_list_next(struct seq_file *p, void *v, loff_t *pos);
1080 static void nfs_server_list_stop(struct seq_file *p, void *v);
1081 static int nfs_server_list_show(struct seq_file *m, void *v);
1082 
1083 static const struct seq_operations nfs_server_list_ops = {
1084 	.start	= nfs_server_list_start,
1085 	.next	= nfs_server_list_next,
1086 	.stop	= nfs_server_list_stop,
1087 	.show	= nfs_server_list_show,
1088 };
1089 
1090 static void *nfs_volume_list_start(struct seq_file *p, loff_t *pos);
1091 static void *nfs_volume_list_next(struct seq_file *p, void *v, loff_t *pos);
1092 static void nfs_volume_list_stop(struct seq_file *p, void *v);
1093 static int nfs_volume_list_show(struct seq_file *m, void *v);
1094 
1095 static const struct seq_operations nfs_volume_list_ops = {
1096 	.start	= nfs_volume_list_start,
1097 	.next	= nfs_volume_list_next,
1098 	.stop	= nfs_volume_list_stop,
1099 	.show	= nfs_volume_list_show,
1100 };
1101 
1102 /*
1103  * set up the iterator to start reading from the server list and return the first item
1104  */
1105 static void *nfs_server_list_start(struct seq_file *m, loff_t *_pos)
1106 				__acquires(&nn->nfs_client_lock)
1107 {
1108 	struct nfs_net *nn = net_generic(seq_file_net(m), nfs_net_id);
1109 
1110 	/* lock the list against modification */
1111 	spin_lock(&nn->nfs_client_lock);
1112 	return seq_list_start_head(&nn->nfs_client_list, *_pos);
1113 }
1114 
1115 /*
1116  * move to next server
1117  */
1118 static void *nfs_server_list_next(struct seq_file *p, void *v, loff_t *pos)
1119 {
1120 	struct nfs_net *nn = net_generic(seq_file_net(p), nfs_net_id);
1121 
1122 	return seq_list_next(v, &nn->nfs_client_list, pos);
1123 }
1124 
1125 /*
1126  * clean up after reading from the transports list
1127  */
1128 static void nfs_server_list_stop(struct seq_file *p, void *v)
1129 				__releases(&nn->nfs_client_lock)
1130 {
1131 	struct nfs_net *nn = net_generic(seq_file_net(p), nfs_net_id);
1132 
1133 	spin_unlock(&nn->nfs_client_lock);
1134 }
1135 
1136 /*
1137  * display a header line followed by a load of call lines
1138  */
1139 static int nfs_server_list_show(struct seq_file *m, void *v)
1140 {
1141 	struct nfs_client *clp;
1142 	struct nfs_net *nn = net_generic(seq_file_net(m), nfs_net_id);
1143 
1144 	/* display header on line 1 */
1145 	if (v == &nn->nfs_client_list) {
1146 		seq_puts(m, "NV SERVER   PORT USE HOSTNAME\n");
1147 		return 0;
1148 	}
1149 
1150 	/* display one transport per line on subsequent lines */
1151 	clp = list_entry(v, struct nfs_client, cl_share_link);
1152 
1153 	/* Check if the client is initialized */
1154 	if (clp->cl_cons_state != NFS_CS_READY)
1155 		return 0;
1156 
1157 	rcu_read_lock();
1158 	seq_printf(m, "v%u %s %s %3d %s\n",
1159 		   clp->rpc_ops->version,
1160 		   rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_HEX_ADDR),
1161 		   rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_HEX_PORT),
1162 		   refcount_read(&clp->cl_count),
1163 		   clp->cl_hostname);
1164 	rcu_read_unlock();
1165 
1166 	return 0;
1167 }
1168 
1169 /*
1170  * set up the iterator to start reading from the volume list and return the first item
1171  */
1172 static void *nfs_volume_list_start(struct seq_file *m, loff_t *_pos)
1173 				__acquires(&nn->nfs_client_lock)
1174 {
1175 	struct nfs_net *nn = net_generic(seq_file_net(m), nfs_net_id);
1176 
1177 	/* lock the list against modification */
1178 	spin_lock(&nn->nfs_client_lock);
1179 	return seq_list_start_head(&nn->nfs_volume_list, *_pos);
1180 }
1181 
1182 /*
1183  * move to next volume
1184  */
1185 static void *nfs_volume_list_next(struct seq_file *p, void *v, loff_t *pos)
1186 {
1187 	struct nfs_net *nn = net_generic(seq_file_net(p), nfs_net_id);
1188 
1189 	return seq_list_next(v, &nn->nfs_volume_list, pos);
1190 }
1191 
1192 /*
1193  * clean up after reading from the transports list
1194  */
1195 static void nfs_volume_list_stop(struct seq_file *p, void *v)
1196 				__releases(&nn->nfs_client_lock)
1197 {
1198 	struct nfs_net *nn = net_generic(seq_file_net(p), nfs_net_id);
1199 
1200 	spin_unlock(&nn->nfs_client_lock);
1201 }
1202 
1203 /*
1204  * display a header line followed by a load of call lines
1205  */
1206 static int nfs_volume_list_show(struct seq_file *m, void *v)
1207 {
1208 	struct nfs_server *server;
1209 	struct nfs_client *clp;
1210 	char dev[13];	// 8 for 2^24, 1 for ':', 3 for 2^8, 1 for '\0'
1211 	char fsid[34];	// 2 * 16 for %llx, 1 for ':', 1 for '\0'
1212 	struct nfs_net *nn = net_generic(seq_file_net(m), nfs_net_id);
1213 
1214 	/* display header on line 1 */
1215 	if (v == &nn->nfs_volume_list) {
1216 		seq_puts(m, "NV SERVER   PORT DEV          FSID"
1217 			    "                              FSC\n");
1218 		return 0;
1219 	}
1220 	/* display one transport per line on subsequent lines */
1221 	server = list_entry(v, struct nfs_server, master_link);
1222 	clp = server->nfs_client;
1223 
1224 	snprintf(dev, sizeof(dev), "%u:%u",
1225 		 MAJOR(server->s_dev), MINOR(server->s_dev));
1226 
1227 	snprintf(fsid, sizeof(fsid), "%llx:%llx",
1228 		 (unsigned long long) server->fsid.major,
1229 		 (unsigned long long) server->fsid.minor);
1230 
1231 	rcu_read_lock();
1232 	seq_printf(m, "v%u %s %s %-12s %-33s %s\n",
1233 		   clp->rpc_ops->version,
1234 		   rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_HEX_ADDR),
1235 		   rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_HEX_PORT),
1236 		   dev,
1237 		   fsid,
1238 		   nfs_server_fscache_state(server));
1239 	rcu_read_unlock();
1240 
1241 	return 0;
1242 }
1243 
1244 int nfs_fs_proc_net_init(struct net *net)
1245 {
1246 	struct nfs_net *nn = net_generic(net, nfs_net_id);
1247 	struct proc_dir_entry *p;
1248 
1249 	nn->proc_nfsfs = proc_net_mkdir(net, "nfsfs", net->proc_net);
1250 	if (!nn->proc_nfsfs)
1251 		goto error_0;
1252 
1253 	/* a file of servers with which we're dealing */
1254 	p = proc_create_net("servers", S_IFREG|S_IRUGO, nn->proc_nfsfs,
1255 			&nfs_server_list_ops, sizeof(struct seq_net_private));
1256 	if (!p)
1257 		goto error_1;
1258 
1259 	/* a file of volumes that we have mounted */
1260 	p = proc_create_net("volumes", S_IFREG|S_IRUGO, nn->proc_nfsfs,
1261 			&nfs_volume_list_ops, sizeof(struct seq_net_private));
1262 	if (!p)
1263 		goto error_1;
1264 	return 0;
1265 
1266 error_1:
1267 	remove_proc_subtree("nfsfs", net->proc_net);
1268 error_0:
1269 	return -ENOMEM;
1270 }
1271 
1272 void nfs_fs_proc_net_exit(struct net *net)
1273 {
1274 	remove_proc_subtree("nfsfs", net->proc_net);
1275 }
1276 
1277 /*
1278  * initialise the /proc/fs/nfsfs/ directory
1279  */
1280 int __init nfs_fs_proc_init(void)
1281 {
1282 	if (!proc_mkdir("fs/nfsfs", NULL))
1283 		goto error_0;
1284 
1285 	/* a file of servers with which we're dealing */
1286 	if (!proc_symlink("fs/nfsfs/servers", NULL, "../../net/nfsfs/servers"))
1287 		goto error_1;
1288 
1289 	/* a file of volumes that we have mounted */
1290 	if (!proc_symlink("fs/nfsfs/volumes", NULL, "../../net/nfsfs/volumes"))
1291 		goto error_1;
1292 
1293 	return 0;
1294 error_1:
1295 	remove_proc_subtree("fs/nfsfs", NULL);
1296 error_0:
1297 	return -ENOMEM;
1298 }
1299 
1300 /*
1301  * clean up the /proc/fs/nfsfs/ directory
1302  */
1303 void nfs_fs_proc_exit(void)
1304 {
1305 	remove_proc_subtree("fs/nfsfs", NULL);
1306 }
1307 
1308 #endif /* CONFIG_PROC_FS */
1309