xref: /openbmc/linux/fs/nfs/nfs4client.c (revision 0545810f)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
4  * Written by David Howells (dhowells@redhat.com)
5  */
6 #include <linux/module.h>
7 #include <linux/nfs_fs.h>
8 #include <linux/nfs_mount.h>
9 #include <linux/sunrpc/addr.h>
10 #include <linux/sunrpc/auth.h>
11 #include <linux/sunrpc/xprt.h>
12 #include <linux/sunrpc/bc_xprt.h>
13 #include <linux/sunrpc/rpc_pipe_fs.h>
14 #include "internal.h"
15 #include "callback.h"
16 #include "delegation.h"
17 #include "nfs4session.h"
18 #include "nfs4idmap.h"
19 #include "pnfs.h"
20 #include "netns.h"
21 
22 #define NFSDBG_FACILITY		NFSDBG_CLIENT
23 
24 /*
25  * Get a unique NFSv4.0 callback identifier which will be used
26  * by the V4.0 callback service to lookup the nfs_client struct
27  */
28 static int nfs_get_cb_ident_idr(struct nfs_client *clp, int minorversion)
29 {
30 	int ret = 0;
31 	struct nfs_net *nn = net_generic(clp->cl_net, nfs_net_id);
32 
33 	if (clp->rpc_ops->version != 4 || minorversion != 0)
34 		return ret;
35 	idr_preload(GFP_KERNEL);
36 	spin_lock(&nn->nfs_client_lock);
37 	ret = idr_alloc(&nn->cb_ident_idr, clp, 1, 0, GFP_NOWAIT);
38 	if (ret >= 0)
39 		clp->cl_cb_ident = ret;
40 	spin_unlock(&nn->nfs_client_lock);
41 	idr_preload_end();
42 	return ret < 0 ? ret : 0;
43 }
44 
45 #ifdef CONFIG_NFS_V4_1
46 /*
47  * Per auth flavor data server rpc clients
48  */
49 struct nfs4_ds_server {
50 	struct list_head	list;   /* ds_clp->cl_ds_clients */
51 	struct rpc_clnt		*rpc_clnt;
52 };
53 
54 /**
55  * nfs4_find_ds_client - Common lookup case for DS I/O
56  * @ds_clp: pointer to the DS's nfs_client
57  * @flavor: rpc auth flavour to match
58  */
59 static struct nfs4_ds_server *
60 nfs4_find_ds_client(struct nfs_client *ds_clp, rpc_authflavor_t flavor)
61 {
62 	struct nfs4_ds_server *dss;
63 
64 	rcu_read_lock();
65 	list_for_each_entry_rcu(dss, &ds_clp->cl_ds_clients, list) {
66 		if (dss->rpc_clnt->cl_auth->au_flavor != flavor)
67 			continue;
68 		goto out;
69 	}
70 	dss = NULL;
71 out:
72 	rcu_read_unlock();
73 	return dss;
74 }
75 
76 static struct nfs4_ds_server *
77 nfs4_add_ds_client(struct nfs_client *ds_clp, rpc_authflavor_t flavor,
78 			   struct nfs4_ds_server *new)
79 {
80 	struct nfs4_ds_server *dss;
81 
82 	spin_lock(&ds_clp->cl_lock);
83 	list_for_each_entry(dss, &ds_clp->cl_ds_clients, list) {
84 		if (dss->rpc_clnt->cl_auth->au_flavor != flavor)
85 			continue;
86 		goto out;
87 	}
88 	if (new)
89 		list_add_rcu(&new->list, &ds_clp->cl_ds_clients);
90 	dss = new;
91 out:
92 	spin_unlock(&ds_clp->cl_lock); /* need some lock to protect list */
93 	return dss;
94 }
95 
96 static struct nfs4_ds_server *
97 nfs4_alloc_ds_server(struct nfs_client *ds_clp, rpc_authflavor_t flavor)
98 {
99 	struct nfs4_ds_server *dss;
100 
101 	dss = kmalloc(sizeof(*dss), GFP_NOFS);
102 	if (dss == NULL)
103 		return ERR_PTR(-ENOMEM);
104 
105 	dss->rpc_clnt = rpc_clone_client_set_auth(ds_clp->cl_rpcclient, flavor);
106 	if (IS_ERR(dss->rpc_clnt)) {
107 		int err = PTR_ERR(dss->rpc_clnt);
108 		kfree (dss);
109 		return ERR_PTR(err);
110 	}
111 	INIT_LIST_HEAD(&dss->list);
112 
113 	return dss;
114 }
115 
116 static void
117 nfs4_free_ds_server(struct nfs4_ds_server *dss)
118 {
119 	rpc_release_client(dss->rpc_clnt);
120 	kfree(dss);
121 }
122 
123 /**
124  * nfs4_find_or_create_ds_client - Find or create a DS rpc client
125  * @ds_clp: pointer to the DS's nfs_client
126  * @inode: pointer to the inode
127  *
128  * Find or create a DS rpc client with th MDS server rpc client auth flavor
129  * in the nfs_client cl_ds_clients list.
130  */
131 struct rpc_clnt *
132 nfs4_find_or_create_ds_client(struct nfs_client *ds_clp, struct inode *inode)
133 {
134 	struct nfs4_ds_server *dss, *new;
135 	rpc_authflavor_t flavor = NFS_SERVER(inode)->client->cl_auth->au_flavor;
136 
137 	dss = nfs4_find_ds_client(ds_clp, flavor);
138 	if (dss != NULL)
139 		goto out;
140 	new = nfs4_alloc_ds_server(ds_clp, flavor);
141 	if (IS_ERR(new))
142 		return ERR_CAST(new);
143 	dss = nfs4_add_ds_client(ds_clp, flavor, new);
144 	if (dss != new)
145 		nfs4_free_ds_server(new);
146 out:
147 	return dss->rpc_clnt;
148 }
149 EXPORT_SYMBOL_GPL(nfs4_find_or_create_ds_client);
150 
151 static void
152 nfs4_shutdown_ds_clients(struct nfs_client *clp)
153 {
154 	struct nfs4_ds_server *dss;
155 
156 	while (!list_empty(&clp->cl_ds_clients)) {
157 		dss = list_entry(clp->cl_ds_clients.next,
158 					struct nfs4_ds_server, list);
159 		list_del(&dss->list);
160 		rpc_shutdown_client(dss->rpc_clnt);
161 		kfree (dss);
162 	}
163 }
164 
165 static void
166 nfs4_cleanup_callback(struct nfs_client *clp)
167 {
168 	struct nfs4_copy_state *cp_state;
169 
170 	while (!list_empty(&clp->pending_cb_stateids)) {
171 		cp_state = list_entry(clp->pending_cb_stateids.next,
172 					struct nfs4_copy_state, copies);
173 		list_del(&cp_state->copies);
174 		kfree(cp_state);
175 	}
176 }
177 
178 void nfs41_shutdown_client(struct nfs_client *clp)
179 {
180 	if (nfs4_has_session(clp)) {
181 		nfs4_cleanup_callback(clp);
182 		nfs4_shutdown_ds_clients(clp);
183 		nfs4_destroy_session(clp->cl_session);
184 		nfs4_destroy_clientid(clp);
185 	}
186 
187 }
188 #endif	/* CONFIG_NFS_V4_1 */
189 
190 void nfs40_shutdown_client(struct nfs_client *clp)
191 {
192 	if (clp->cl_slot_tbl) {
193 		nfs4_shutdown_slot_table(clp->cl_slot_tbl);
194 		kfree(clp->cl_slot_tbl);
195 	}
196 }
197 
198 struct nfs_client *nfs4_alloc_client(const struct nfs_client_initdata *cl_init)
199 {
200 	char buf[INET6_ADDRSTRLEN + 1];
201 	const char *ip_addr = cl_init->ip_addr;
202 	struct nfs_client *clp = nfs_alloc_client(cl_init);
203 	int err;
204 
205 	if (IS_ERR(clp))
206 		return clp;
207 
208 	err = nfs_get_cb_ident_idr(clp, cl_init->minorversion);
209 	if (err)
210 		goto error;
211 
212 	if (cl_init->minorversion > NFS4_MAX_MINOR_VERSION) {
213 		err = -EINVAL;
214 		goto error;
215 	}
216 
217 	spin_lock_init(&clp->cl_lock);
218 	INIT_DELAYED_WORK(&clp->cl_renewd, nfs4_renew_state);
219 	INIT_LIST_HEAD(&clp->cl_ds_clients);
220 	rpc_init_wait_queue(&clp->cl_rpcwaitq, "NFS client");
221 	clp->cl_state = 1 << NFS4CLNT_LEASE_EXPIRED;
222 	clp->cl_mvops = nfs_v4_minor_ops[cl_init->minorversion];
223 	clp->cl_mig_gen = 1;
224 #if IS_ENABLED(CONFIG_NFS_V4_1)
225 	init_waitqueue_head(&clp->cl_lock_waitq);
226 #endif
227 	INIT_LIST_HEAD(&clp->pending_cb_stateids);
228 
229 	if (cl_init->minorversion != 0)
230 		__set_bit(NFS_CS_INFINITE_SLOTS, &clp->cl_flags);
231 	__set_bit(NFS_CS_DISCRTRY, &clp->cl_flags);
232 	__set_bit(NFS_CS_NO_RETRANS_TIMEOUT, &clp->cl_flags);
233 
234 	/*
235 	 * Set up the connection to the server before we add add to the
236 	 * global list.
237 	 */
238 	err = nfs_create_rpc_client(clp, cl_init, RPC_AUTH_GSS_KRB5I);
239 	if (err == -EINVAL)
240 		err = nfs_create_rpc_client(clp, cl_init, RPC_AUTH_UNIX);
241 	if (err < 0)
242 		goto error;
243 
244 	/* If no clientaddr= option was specified, find a usable cb address */
245 	if (ip_addr == NULL) {
246 		struct sockaddr_storage cb_addr;
247 		struct sockaddr *sap = (struct sockaddr *)&cb_addr;
248 
249 		err = rpc_localaddr(clp->cl_rpcclient, sap, sizeof(cb_addr));
250 		if (err < 0)
251 			goto error;
252 		err = rpc_ntop(sap, buf, sizeof(buf));
253 		if (err < 0)
254 			goto error;
255 		ip_addr = (const char *)buf;
256 	}
257 	strscpy(clp->cl_ipaddr, ip_addr, sizeof(clp->cl_ipaddr));
258 
259 	err = nfs_idmap_new(clp);
260 	if (err < 0) {
261 		dprintk("%s: failed to create idmapper. Error = %d\n",
262 			__func__, err);
263 		goto error;
264 	}
265 	__set_bit(NFS_CS_IDMAP, &clp->cl_res_state);
266 	return clp;
267 
268 error:
269 	nfs_free_client(clp);
270 	return ERR_PTR(err);
271 }
272 
273 /*
274  * Destroy the NFS4 callback service
275  */
276 static void nfs4_destroy_callback(struct nfs_client *clp)
277 {
278 	if (__test_and_clear_bit(NFS_CS_CALLBACK, &clp->cl_res_state))
279 		nfs_callback_down(clp->cl_mvops->minor_version, clp->cl_net);
280 }
281 
282 static void nfs4_shutdown_client(struct nfs_client *clp)
283 {
284 	if (__test_and_clear_bit(NFS_CS_RENEWD, &clp->cl_res_state))
285 		nfs4_kill_renewd(clp);
286 	clp->cl_mvops->shutdown_client(clp);
287 	nfs4_destroy_callback(clp);
288 	if (__test_and_clear_bit(NFS_CS_IDMAP, &clp->cl_res_state))
289 		nfs_idmap_delete(clp);
290 
291 	rpc_destroy_wait_queue(&clp->cl_rpcwaitq);
292 	kfree(clp->cl_serverowner);
293 	kfree(clp->cl_serverscope);
294 	kfree(clp->cl_implid);
295 	kfree(clp->cl_owner_id);
296 }
297 
298 void nfs4_free_client(struct nfs_client *clp)
299 {
300 	nfs4_shutdown_client(clp);
301 	nfs_free_client(clp);
302 }
303 
304 /*
305  * Initialize the NFS4 callback service
306  */
307 static int nfs4_init_callback(struct nfs_client *clp)
308 {
309 	struct rpc_xprt *xprt;
310 	int error;
311 
312 	xprt = rcu_dereference_raw(clp->cl_rpcclient->cl_xprt);
313 
314 	if (nfs4_has_session(clp)) {
315 		error = xprt_setup_backchannel(xprt, NFS41_BC_MIN_CALLBACKS);
316 		if (error < 0)
317 			return error;
318 	}
319 
320 	error = nfs_callback_up(clp->cl_mvops->minor_version, xprt);
321 	if (error < 0) {
322 		dprintk("%s: failed to start callback. Error = %d\n",
323 			__func__, error);
324 		return error;
325 	}
326 	__set_bit(NFS_CS_CALLBACK, &clp->cl_res_state);
327 
328 	return 0;
329 }
330 
331 /**
332  * nfs40_init_client - nfs_client initialization tasks for NFSv4.0
333  * @clp: nfs_client to initialize
334  *
335  * Returns zero on success, or a negative errno if some error occurred.
336  */
337 int nfs40_init_client(struct nfs_client *clp)
338 {
339 	struct nfs4_slot_table *tbl;
340 	int ret;
341 
342 	tbl = kzalloc(sizeof(*tbl), GFP_NOFS);
343 	if (tbl == NULL)
344 		return -ENOMEM;
345 
346 	ret = nfs4_setup_slot_table(tbl, NFS4_MAX_SLOT_TABLE,
347 					"NFSv4.0 transport Slot table");
348 	if (ret) {
349 		nfs4_shutdown_slot_table(tbl);
350 		kfree(tbl);
351 		return ret;
352 	}
353 
354 	clp->cl_slot_tbl = tbl;
355 	return 0;
356 }
357 
358 #if defined(CONFIG_NFS_V4_1)
359 
360 /**
361  * nfs41_init_client - nfs_client initialization tasks for NFSv4.1+
362  * @clp: nfs_client to initialize
363  *
364  * Returns zero on success, or a negative errno if some error occurred.
365  */
366 int nfs41_init_client(struct nfs_client *clp)
367 {
368 	struct nfs4_session *session = NULL;
369 
370 	/*
371 	 * Create the session and mark it expired.
372 	 * When a SEQUENCE operation encounters the expired session
373 	 * it will do session recovery to initialize it.
374 	 */
375 	session = nfs4_alloc_session(clp);
376 	if (!session)
377 		return -ENOMEM;
378 
379 	clp->cl_session = session;
380 
381 	/*
382 	 * The create session reply races with the server back
383 	 * channel probe. Mark the client NFS_CS_SESSION_INITING
384 	 * so that the client back channel can find the
385 	 * nfs_client struct
386 	 */
387 	nfs_mark_client_ready(clp, NFS_CS_SESSION_INITING);
388 	return 0;
389 }
390 
391 #endif	/* CONFIG_NFS_V4_1 */
392 
393 /*
394  * Initialize the minor version specific parts of an NFS4 client record
395  */
396 static int nfs4_init_client_minor_version(struct nfs_client *clp)
397 {
398 	int ret;
399 
400 	ret = clp->cl_mvops->init_client(clp);
401 	if (ret)
402 		return ret;
403 	return nfs4_init_callback(clp);
404 }
405 
406 static void nfs4_add_trunk(struct nfs_client *clp, struct nfs_client *old)
407 {
408 	struct sockaddr_storage clp_addr, old_addr;
409 	struct sockaddr *clp_sap = (struct sockaddr *)&clp_addr;
410 	struct sockaddr *old_sap = (struct sockaddr *)&old_addr;
411 	size_t clp_salen;
412 	struct xprt_create xprt_args = {
413 		.ident = old->cl_proto,
414 		.net = old->cl_net,
415 		.servername = old->cl_hostname,
416 	};
417 
418 	if (clp->cl_proto != old->cl_proto)
419 		return;
420 	clp_salen = rpc_peeraddr(clp->cl_rpcclient, clp_sap, sizeof(clp_addr));
421 	rpc_peeraddr(old->cl_rpcclient, old_sap, sizeof(old_addr));
422 
423 	if (clp_addr.ss_family != old_addr.ss_family)
424 		return;
425 
426 	xprt_args.dstaddr = clp_sap;
427 	xprt_args.addrlen = clp_salen;
428 
429 	rpc_clnt_add_xprt(old->cl_rpcclient, &xprt_args,
430 			  rpc_clnt_test_and_add_xprt, NULL);
431 }
432 
433 /**
434  * nfs4_init_client - Initialise an NFS4 client record
435  *
436  * @clp: nfs_client to initialise
437  * @cl_init: pointer to nfs_client_initdata
438  *
439  * Returns pointer to an NFS client, or an ERR_PTR value.
440  */
441 struct nfs_client *nfs4_init_client(struct nfs_client *clp,
442 				    const struct nfs_client_initdata *cl_init)
443 {
444 	struct nfs_client *old;
445 	int error;
446 
447 	if (clp->cl_cons_state == NFS_CS_READY)
448 		/* the client is initialised already */
449 		return clp;
450 
451 	error = nfs4_init_client_minor_version(clp);
452 	if (error < 0)
453 		goto error;
454 
455 	error = nfs4_discover_server_trunking(clp, &old);
456 	if (error < 0)
457 		goto error;
458 
459 	if (clp != old) {
460 		clp->cl_preserve_clid = true;
461 		/*
462 		 * Mark the client as having failed initialization so other
463 		 * processes walking the nfs_client_list in nfs_match_client()
464 		 * won't try to use it.
465 		 */
466 		nfs_mark_client_ready(clp, -EPERM);
467 		if (old->cl_mvops->session_trunk)
468 			nfs4_add_trunk(clp, old);
469 	}
470 	clear_bit(NFS_CS_TSM_POSSIBLE, &clp->cl_flags);
471 	nfs_put_client(clp);
472 	return old;
473 
474 error:
475 	nfs_mark_client_ready(clp, error);
476 	nfs_put_client(clp);
477 	return ERR_PTR(error);
478 }
479 
480 /*
481  * SETCLIENTID just did a callback update with the callback ident in
482  * "drop," but server trunking discovery claims "drop" and "keep" are
483  * actually the same server.  Swap the callback IDs so that "keep"
484  * will continue to use the callback ident the server now knows about,
485  * and so that "keep"'s original callback ident is destroyed when
486  * "drop" is freed.
487  */
488 static void nfs4_swap_callback_idents(struct nfs_client *keep,
489 				      struct nfs_client *drop)
490 {
491 	struct nfs_net *nn = net_generic(keep->cl_net, nfs_net_id);
492 	unsigned int save = keep->cl_cb_ident;
493 
494 	if (keep->cl_cb_ident == drop->cl_cb_ident)
495 		return;
496 
497 	dprintk("%s: keeping callback ident %u and dropping ident %u\n",
498 		__func__, keep->cl_cb_ident, drop->cl_cb_ident);
499 
500 	spin_lock(&nn->nfs_client_lock);
501 
502 	idr_replace(&nn->cb_ident_idr, keep, drop->cl_cb_ident);
503 	keep->cl_cb_ident = drop->cl_cb_ident;
504 
505 	idr_replace(&nn->cb_ident_idr, drop, save);
506 	drop->cl_cb_ident = save;
507 
508 	spin_unlock(&nn->nfs_client_lock);
509 }
510 
511 static bool nfs4_match_client_owner_id(const struct nfs_client *clp1,
512 		const struct nfs_client *clp2)
513 {
514 	if (clp1->cl_owner_id == NULL || clp2->cl_owner_id == NULL)
515 		return true;
516 	return strcmp(clp1->cl_owner_id, clp2->cl_owner_id) == 0;
517 }
518 
519 static bool nfs4_same_verifier(nfs4_verifier *v1, nfs4_verifier *v2)
520 {
521 	return memcmp(v1->data, v2->data, sizeof(v1->data)) == 0;
522 }
523 
524 static int nfs4_match_client(struct nfs_client  *pos,  struct nfs_client *new,
525 			     struct nfs_client **prev, struct nfs_net *nn)
526 {
527 	int status;
528 
529 	if (pos->rpc_ops != new->rpc_ops)
530 		return 1;
531 
532 	if (pos->cl_minorversion != new->cl_minorversion)
533 		return 1;
534 
535 	/* If "pos" isn't marked ready, we can't trust the
536 	 * remaining fields in "pos", especially the client
537 	 * ID and serverowner fields.  Wait for CREATE_SESSION
538 	 * to finish. */
539 	if (pos->cl_cons_state > NFS_CS_READY) {
540 		refcount_inc(&pos->cl_count);
541 		spin_unlock(&nn->nfs_client_lock);
542 
543 		nfs_put_client(*prev);
544 		*prev = pos;
545 
546 		status = nfs_wait_client_init_complete(pos);
547 		spin_lock(&nn->nfs_client_lock);
548 
549 		if (status < 0)
550 			return status;
551 	}
552 
553 	if (pos->cl_cons_state != NFS_CS_READY)
554 		return 1;
555 
556 	if (pos->cl_clientid != new->cl_clientid)
557 		return 1;
558 
559 	/* NFSv4.1 always uses the uniform string, however someone
560 	 * might switch the uniquifier string on us.
561 	 */
562 	if (!nfs4_match_client_owner_id(pos, new))
563 		return 1;
564 
565 	return 0;
566 }
567 
568 /**
569  * nfs40_walk_client_list - Find server that recognizes a client ID
570  *
571  * @new: nfs_client with client ID to test
572  * @result: OUT: found nfs_client, or new
573  * @cred: credential to use for trunking test
574  *
575  * Returns zero, a negative errno, or a negative NFS4ERR status.
576  * If zero is returned, an nfs_client pointer is planted in "result."
577  *
578  * NB: nfs40_walk_client_list() relies on the new nfs_client being
579  *     the last nfs_client on the list.
580  */
581 int nfs40_walk_client_list(struct nfs_client *new,
582 			   struct nfs_client **result,
583 			   const struct cred *cred)
584 {
585 	struct nfs_net *nn = net_generic(new->cl_net, nfs_net_id);
586 	struct nfs_client *pos, *prev = NULL;
587 	struct nfs4_setclientid_res clid = {
588 		.clientid	= new->cl_clientid,
589 		.confirm	= new->cl_confirm,
590 	};
591 	int status = -NFS4ERR_STALE_CLIENTID;
592 
593 	spin_lock(&nn->nfs_client_lock);
594 	list_for_each_entry(pos, &nn->nfs_client_list, cl_share_link) {
595 
596 		if (pos == new)
597 			goto found;
598 
599 		status = nfs4_match_client(pos, new, &prev, nn);
600 		if (status < 0)
601 			goto out_unlock;
602 		if (status != 0)
603 			continue;
604 		/*
605 		 * We just sent a new SETCLIENTID, which should have
606 		 * caused the server to return a new cl_confirm.  So if
607 		 * cl_confirm is the same, then this is a different
608 		 * server that just returned the same cl_confirm by
609 		 * coincidence:
610 		 */
611 		if ((new != pos) && nfs4_same_verifier(&pos->cl_confirm,
612 						       &new->cl_confirm))
613 			continue;
614 		/*
615 		 * But if the cl_confirm's are different, then the only
616 		 * way that a SETCLIENTID_CONFIRM to pos can succeed is
617 		 * if new and pos point to the same server:
618 		 */
619 found:
620 		refcount_inc(&pos->cl_count);
621 		spin_unlock(&nn->nfs_client_lock);
622 
623 		nfs_put_client(prev);
624 		prev = pos;
625 
626 		status = nfs4_proc_setclientid_confirm(pos, &clid, cred);
627 		switch (status) {
628 		case -NFS4ERR_STALE_CLIENTID:
629 			break;
630 		case 0:
631 			nfs4_swap_callback_idents(pos, new);
632 			pos->cl_confirm = new->cl_confirm;
633 			nfs_mark_client_ready(pos, NFS_CS_READY);
634 
635 			prev = NULL;
636 			*result = pos;
637 			goto out;
638 		case -ERESTARTSYS:
639 		case -ETIMEDOUT:
640 			/* The callback path may have been inadvertently
641 			 * changed. Schedule recovery!
642 			 */
643 			nfs4_schedule_path_down_recovery(pos);
644 			goto out;
645 		default:
646 			goto out;
647 		}
648 
649 		spin_lock(&nn->nfs_client_lock);
650 	}
651 out_unlock:
652 	spin_unlock(&nn->nfs_client_lock);
653 
654 	/* No match found. The server lost our clientid */
655 out:
656 	nfs_put_client(prev);
657 	return status;
658 }
659 
660 #ifdef CONFIG_NFS_V4_1
661 /*
662  * Returns true if the server major ids match
663  */
664 bool
665 nfs4_check_serverowner_major_id(struct nfs41_server_owner *o1,
666 				struct nfs41_server_owner *o2)
667 {
668 	if (o1->major_id_sz != o2->major_id_sz)
669 		return false;
670 	return memcmp(o1->major_id, o2->major_id, o1->major_id_sz) == 0;
671 }
672 
673 /*
674  * Returns true if the server scopes match
675  */
676 static bool
677 nfs4_check_server_scope(struct nfs41_server_scope *s1,
678 			struct nfs41_server_scope *s2)
679 {
680 	if (s1->server_scope_sz != s2->server_scope_sz)
681 		return false;
682 	return memcmp(s1->server_scope, s2->server_scope,
683 					s1->server_scope_sz) == 0;
684 }
685 
686 /**
687  * nfs4_detect_session_trunking - Checks for session trunking.
688  * @clp:    original mount nfs_client
689  * @res:    result structure from an exchange_id using the original mount
690  *          nfs_client with a new multi_addr transport
691  * @xprt:   pointer to the transport to add.
692  *
693  * Called after a successful EXCHANGE_ID on a multi-addr connection.
694  * Upon success, add the transport.
695  *
696  * Returns zero on success, otherwise -EINVAL
697  *
698  * Note: since the exchange_id for the new multi_addr transport uses the
699  * same nfs_client from the original mount, the cl_owner_id is reused,
700  * so eir_clientowner is the same.
701  */
702 int nfs4_detect_session_trunking(struct nfs_client *clp,
703 				 struct nfs41_exchange_id_res *res,
704 				 struct rpc_xprt *xprt)
705 {
706 	/* Check eir_clientid */
707 	if (clp->cl_clientid != res->clientid)
708 		goto out_err;
709 
710 	/* Check eir_server_owner so_major_id */
711 	if (!nfs4_check_serverowner_major_id(clp->cl_serverowner,
712 					     res->server_owner))
713 		goto out_err;
714 
715 	/* Check eir_server_owner so_minor_id */
716 	if (clp->cl_serverowner->minor_id != res->server_owner->minor_id)
717 		goto out_err;
718 
719 	/* Check eir_server_scope */
720 	if (!nfs4_check_server_scope(clp->cl_serverscope, res->server_scope))
721 		goto out_err;
722 
723 	pr_info("NFS:  %s: Session trunking succeeded for %s\n",
724 		clp->cl_hostname,
725 		xprt->address_strings[RPC_DISPLAY_ADDR]);
726 
727 	return 0;
728 out_err:
729 	pr_info("NFS:  %s: Session trunking failed for %s\n", clp->cl_hostname,
730 		xprt->address_strings[RPC_DISPLAY_ADDR]);
731 
732 	return -EINVAL;
733 }
734 
735 /**
736  * nfs41_walk_client_list - Find nfs_client that matches a client/server owner
737  *
738  * @new: nfs_client with client ID to test
739  * @result: OUT: found nfs_client, or new
740  * @cred: credential to use for trunking test
741  *
742  * Returns zero, a negative errno, or a negative NFS4ERR status.
743  * If zero is returned, an nfs_client pointer is planted in "result."
744  *
745  * NB: nfs41_walk_client_list() relies on the new nfs_client being
746  *     the last nfs_client on the list.
747  */
748 int nfs41_walk_client_list(struct nfs_client *new,
749 			   struct nfs_client **result,
750 			   const struct cred *cred)
751 {
752 	struct nfs_net *nn = net_generic(new->cl_net, nfs_net_id);
753 	struct nfs_client *pos, *prev = NULL;
754 	int status = -NFS4ERR_STALE_CLIENTID;
755 
756 	spin_lock(&nn->nfs_client_lock);
757 	list_for_each_entry(pos, &nn->nfs_client_list, cl_share_link) {
758 
759 		if (pos == new)
760 			goto found;
761 
762 		status = nfs4_match_client(pos, new, &prev, nn);
763 		if (status < 0)
764 			goto out;
765 		if (status != 0)
766 			continue;
767 
768 		/*
769 		 * Note that session trunking is just a special subcase of
770 		 * client id trunking. In either case, we want to fall back
771 		 * to using the existing nfs_client.
772 		 */
773 		if (!nfs4_check_serverowner_major_id(pos->cl_serverowner,
774 						     new->cl_serverowner))
775 			continue;
776 
777 found:
778 		refcount_inc(&pos->cl_count);
779 		*result = pos;
780 		status = 0;
781 		break;
782 	}
783 
784 out:
785 	spin_unlock(&nn->nfs_client_lock);
786 	nfs_put_client(prev);
787 	return status;
788 }
789 #endif	/* CONFIG_NFS_V4_1 */
790 
791 static void nfs4_destroy_server(struct nfs_server *server)
792 {
793 	LIST_HEAD(freeme);
794 
795 	nfs_server_return_all_delegations(server);
796 	unset_pnfs_layoutdriver(server);
797 	nfs4_purge_state_owners(server, &freeme);
798 	nfs4_free_state_owners(&freeme);
799 }
800 
801 /*
802  * NFSv4.0 callback thread helper
803  *
804  * Find a client by callback identifier
805  */
806 struct nfs_client *
807 nfs4_find_client_ident(struct net *net, int cb_ident)
808 {
809 	struct nfs_client *clp;
810 	struct nfs_net *nn = net_generic(net, nfs_net_id);
811 
812 	spin_lock(&nn->nfs_client_lock);
813 	clp = idr_find(&nn->cb_ident_idr, cb_ident);
814 	if (clp)
815 		refcount_inc(&clp->cl_count);
816 	spin_unlock(&nn->nfs_client_lock);
817 	return clp;
818 }
819 
820 #if defined(CONFIG_NFS_V4_1)
821 /* Common match routine for v4.0 and v4.1 callback services */
822 static bool nfs4_cb_match_client(const struct sockaddr *addr,
823 		struct nfs_client *clp, u32 minorversion)
824 {
825 	struct sockaddr *clap = (struct sockaddr *)&clp->cl_addr;
826 
827 	/* Don't match clients that failed to initialise */
828 	if (!(clp->cl_cons_state == NFS_CS_READY ||
829 	    clp->cl_cons_state == NFS_CS_SESSION_INITING))
830 		return false;
831 
832 	smp_rmb();
833 
834 	/* Match the version and minorversion */
835 	if (clp->rpc_ops->version != 4 ||
836 	    clp->cl_minorversion != minorversion)
837 		return false;
838 
839 	/* Match only the IP address, not the port number */
840 	return rpc_cmp_addr(addr, clap);
841 }
842 
843 /*
844  * NFSv4.1 callback thread helper
845  * For CB_COMPOUND calls, find a client by IP address, protocol version,
846  * minorversion, and sessionID
847  *
848  * Returns NULL if no such client
849  */
850 struct nfs_client *
851 nfs4_find_client_sessionid(struct net *net, const struct sockaddr *addr,
852 			   struct nfs4_sessionid *sid, u32 minorversion)
853 {
854 	struct nfs_client *clp;
855 	struct nfs_net *nn = net_generic(net, nfs_net_id);
856 
857 	spin_lock(&nn->nfs_client_lock);
858 	list_for_each_entry(clp, &nn->nfs_client_list, cl_share_link) {
859 		if (!nfs4_cb_match_client(addr, clp, minorversion))
860 			continue;
861 
862 		if (!nfs4_has_session(clp))
863 			continue;
864 
865 		/* Match sessionid*/
866 		if (memcmp(clp->cl_session->sess_id.data,
867 		    sid->data, NFS4_MAX_SESSIONID_LEN) != 0)
868 			continue;
869 
870 		refcount_inc(&clp->cl_count);
871 		spin_unlock(&nn->nfs_client_lock);
872 		return clp;
873 	}
874 	spin_unlock(&nn->nfs_client_lock);
875 	return NULL;
876 }
877 
878 #else /* CONFIG_NFS_V4_1 */
879 
880 struct nfs_client *
881 nfs4_find_client_sessionid(struct net *net, const struct sockaddr *addr,
882 			   struct nfs4_sessionid *sid, u32 minorversion)
883 {
884 	return NULL;
885 }
886 #endif /* CONFIG_NFS_V4_1 */
887 
888 /*
889  * Set up an NFS4 client
890  */
891 static int nfs4_set_client(struct nfs_server *server,
892 		const char *hostname,
893 		const struct sockaddr_storage *addr,
894 		const size_t addrlen,
895 		const char *ip_addr,
896 		int proto, const struct rpc_timeout *timeparms,
897 		u32 minorversion, unsigned int nconnect,
898 		unsigned int max_connect,
899 		struct net *net)
900 {
901 	struct nfs_client_initdata cl_init = {
902 		.hostname = hostname,
903 		.addr = addr,
904 		.addrlen = addrlen,
905 		.ip_addr = ip_addr,
906 		.nfs_mod = &nfs_v4,
907 		.proto = proto,
908 		.minorversion = minorversion,
909 		.net = net,
910 		.timeparms = timeparms,
911 		.cred = server->cred,
912 	};
913 	struct nfs_client *clp;
914 
915 	if (minorversion == 0)
916 		__set_bit(NFS_CS_REUSEPORT, &cl_init.init_flags);
917 	else
918 		cl_init.max_connect = max_connect;
919 	if (proto == XPRT_TRANSPORT_TCP)
920 		cl_init.nconnect = nconnect;
921 
922 	if (server->flags & NFS_MOUNT_NORESVPORT)
923 		__set_bit(NFS_CS_NORESVPORT, &cl_init.init_flags);
924 	if (server->options & NFS_OPTION_MIGRATION)
925 		__set_bit(NFS_CS_MIGRATION, &cl_init.init_flags);
926 	if (test_bit(NFS_MIG_TSM_POSSIBLE, &server->mig_status))
927 		__set_bit(NFS_CS_TSM_POSSIBLE, &cl_init.init_flags);
928 	server->port = rpc_get_port((struct sockaddr *)addr);
929 
930 	/* Allocate or find a client reference we can use */
931 	clp = nfs_get_client(&cl_init);
932 	if (IS_ERR(clp))
933 		return PTR_ERR(clp);
934 
935 	if (server->nfs_client == clp) {
936 		nfs_put_client(clp);
937 		return -ELOOP;
938 	}
939 
940 	/*
941 	 * Query for the lease time on clientid setup or renewal
942 	 *
943 	 * Note that this will be set on nfs_clients that were created
944 	 * only for the DS role and did not set this bit, but now will
945 	 * serve a dual role.
946 	 */
947 	set_bit(NFS_CS_CHECK_LEASE_TIME, &clp->cl_res_state);
948 
949 	server->nfs_client = clp;
950 	return 0;
951 }
952 
953 /*
954  * Set up a pNFS Data Server client.
955  *
956  * Return any existing nfs_client that matches server address,port,version
957  * and minorversion.
958  *
959  * For a new nfs_client, use a soft mount (default), a low retrans and a
960  * low timeout interval so that if a connection is lost, we retry through
961  * the MDS.
962  */
963 struct nfs_client *nfs4_set_ds_client(struct nfs_server *mds_srv,
964 		const struct sockaddr_storage *ds_addr, int ds_addrlen,
965 		int ds_proto, unsigned int ds_timeo, unsigned int ds_retrans,
966 		u32 minor_version)
967 {
968 	struct rpc_timeout ds_timeout;
969 	struct nfs_client *mds_clp = mds_srv->nfs_client;
970 	struct nfs_client_initdata cl_init = {
971 		.addr = ds_addr,
972 		.addrlen = ds_addrlen,
973 		.nodename = mds_clp->cl_rpcclient->cl_nodename,
974 		.ip_addr = mds_clp->cl_ipaddr,
975 		.nfs_mod = &nfs_v4,
976 		.proto = ds_proto,
977 		.minorversion = minor_version,
978 		.net = mds_clp->cl_net,
979 		.timeparms = &ds_timeout,
980 		.cred = mds_srv->cred,
981 	};
982 	char buf[INET6_ADDRSTRLEN + 1];
983 
984 	if (rpc_ntop((struct sockaddr *)ds_addr, buf, sizeof(buf)) <= 0)
985 		return ERR_PTR(-EINVAL);
986 	cl_init.hostname = buf;
987 
988 	if (mds_clp->cl_nconnect > 1 && ds_proto == XPRT_TRANSPORT_TCP) {
989 		cl_init.nconnect = mds_clp->cl_nconnect;
990 		cl_init.max_connect = NFS_MAX_TRANSPORTS;
991 	}
992 
993 	if (mds_srv->flags & NFS_MOUNT_NORESVPORT)
994 		__set_bit(NFS_CS_NORESVPORT, &cl_init.init_flags);
995 
996 	/*
997 	 * Set an authflavor equual to the MDS value. Use the MDS nfs_client
998 	 * cl_ipaddr so as to use the same EXCHANGE_ID co_ownerid as the MDS
999 	 * (section 13.1 RFC 5661).
1000 	 */
1001 	nfs_init_timeout_values(&ds_timeout, ds_proto, ds_timeo, ds_retrans);
1002 	return nfs_get_client(&cl_init);
1003 }
1004 EXPORT_SYMBOL_GPL(nfs4_set_ds_client);
1005 
1006 /*
1007  * Session has been established, and the client marked ready.
1008  * Limit the mount rsize, wsize and dtsize using negotiated fore
1009  * channel attributes.
1010  */
1011 static void nfs4_session_limit_rwsize(struct nfs_server *server)
1012 {
1013 #ifdef CONFIG_NFS_V4_1
1014 	struct nfs4_session *sess;
1015 	u32 server_resp_sz;
1016 	u32 server_rqst_sz;
1017 
1018 	if (!nfs4_has_session(server->nfs_client))
1019 		return;
1020 	sess = server->nfs_client->cl_session;
1021 	server_resp_sz = sess->fc_attrs.max_resp_sz - nfs41_maxread_overhead;
1022 	server_rqst_sz = sess->fc_attrs.max_rqst_sz - nfs41_maxwrite_overhead;
1023 
1024 	if (server->dtsize > server_resp_sz)
1025 		server->dtsize = server_resp_sz;
1026 	if (server->rsize > server_resp_sz)
1027 		server->rsize = server_resp_sz;
1028 	if (server->wsize > server_rqst_sz)
1029 		server->wsize = server_rqst_sz;
1030 #endif /* CONFIG_NFS_V4_1 */
1031 }
1032 
1033 /*
1034  * Limit xattr sizes using the channel attributes.
1035  */
1036 static void nfs4_session_limit_xasize(struct nfs_server *server)
1037 {
1038 #ifdef CONFIG_NFS_V4_2
1039 	struct nfs4_session *sess;
1040 	u32 server_gxa_sz;
1041 	u32 server_sxa_sz;
1042 	u32 server_lxa_sz;
1043 
1044 	if (!nfs4_has_session(server->nfs_client))
1045 		return;
1046 
1047 	sess = server->nfs_client->cl_session;
1048 
1049 	server_gxa_sz = sess->fc_attrs.max_resp_sz - nfs42_maxgetxattr_overhead;
1050 	server_sxa_sz = sess->fc_attrs.max_rqst_sz - nfs42_maxsetxattr_overhead;
1051 	server_lxa_sz = sess->fc_attrs.max_resp_sz -
1052 	    nfs42_maxlistxattrs_overhead;
1053 
1054 	if (server->gxasize > server_gxa_sz)
1055 		server->gxasize = server_gxa_sz;
1056 	if (server->sxasize > server_sxa_sz)
1057 		server->sxasize = server_sxa_sz;
1058 	if (server->lxasize > server_lxa_sz)
1059 		server->lxasize = server_lxa_sz;
1060 #endif
1061 }
1062 
1063 void nfs4_server_set_init_caps(struct nfs_server *server)
1064 {
1065 	/* Set the basic capabilities */
1066 	server->caps |= server->nfs_client->cl_mvops->init_caps;
1067 	if (server->flags & NFS_MOUNT_NORDIRPLUS)
1068 			server->caps &= ~NFS_CAP_READDIRPLUS;
1069 	if (server->nfs_client->cl_proto == XPRT_TRANSPORT_RDMA)
1070 		server->caps &= ~NFS_CAP_READ_PLUS;
1071 
1072 	/*
1073 	 * Don't use NFS uid/gid mapping if we're using AUTH_SYS or lower
1074 	 * authentication.
1075 	 */
1076 	if (nfs4_disable_idmapping &&
1077 			server->client->cl_auth->au_flavor == RPC_AUTH_UNIX)
1078 		server->caps |= NFS_CAP_UIDGID_NOMAP;
1079 }
1080 
1081 static int nfs4_server_common_setup(struct nfs_server *server,
1082 		struct nfs_fh *mntfh, bool auth_probe)
1083 {
1084 	int error;
1085 
1086 	/* data servers support only a subset of NFSv4.1 */
1087 	if (is_ds_only_client(server->nfs_client))
1088 		return -EPROTONOSUPPORT;
1089 
1090 	/* We must ensure the session is initialised first */
1091 	error = nfs4_init_session(server->nfs_client);
1092 	if (error < 0)
1093 		goto out;
1094 
1095 	nfs4_server_set_init_caps(server);
1096 
1097 	/* Probe the root fh to retrieve its FSID and filehandle */
1098 	error = nfs4_get_rootfh(server, mntfh, auth_probe);
1099 	if (error < 0)
1100 		goto out;
1101 
1102 	dprintk("Server FSID: %llx:%llx\n",
1103 			(unsigned long long) server->fsid.major,
1104 			(unsigned long long) server->fsid.minor);
1105 	nfs_display_fhandle(mntfh, "Pseudo-fs root FH");
1106 
1107 	error = nfs_probe_server(server, mntfh);
1108 	if (error < 0)
1109 		goto out;
1110 
1111 	nfs4_session_limit_rwsize(server);
1112 	nfs4_session_limit_xasize(server);
1113 
1114 	if (server->namelen == 0 || server->namelen > NFS4_MAXNAMLEN)
1115 		server->namelen = NFS4_MAXNAMLEN;
1116 
1117 	nfs_server_insert_lists(server);
1118 	server->mount_time = jiffies;
1119 	server->destroy = nfs4_destroy_server;
1120 out:
1121 	return error;
1122 }
1123 
1124 /*
1125  * Create a version 4 volume record
1126  */
1127 static int nfs4_init_server(struct nfs_server *server, struct fs_context *fc)
1128 {
1129 	struct nfs_fs_context *ctx = nfs_fc2context(fc);
1130 	struct rpc_timeout timeparms;
1131 	int error;
1132 
1133 	nfs_init_timeout_values(&timeparms, ctx->nfs_server.protocol,
1134 				ctx->timeo, ctx->retrans);
1135 
1136 	/* Initialise the client representation from the mount data */
1137 	server->flags = ctx->flags;
1138 	server->options = ctx->options;
1139 	server->auth_info = ctx->auth_info;
1140 
1141 	/* Use the first specified auth flavor. If this flavor isn't
1142 	 * allowed by the server, use the SECINFO path to try the
1143 	 * other specified flavors */
1144 	if (ctx->auth_info.flavor_len >= 1)
1145 		ctx->selected_flavor = ctx->auth_info.flavors[0];
1146 	else
1147 		ctx->selected_flavor = RPC_AUTH_UNIX;
1148 
1149 	/* Get a client record */
1150 	error = nfs4_set_client(server,
1151 				ctx->nfs_server.hostname,
1152 				&ctx->nfs_server._address,
1153 				ctx->nfs_server.addrlen,
1154 				ctx->client_address,
1155 				ctx->nfs_server.protocol,
1156 				&timeparms,
1157 				ctx->minorversion,
1158 				ctx->nfs_server.nconnect,
1159 				ctx->nfs_server.max_connect,
1160 				fc->net_ns);
1161 	if (error < 0)
1162 		return error;
1163 
1164 	if (ctx->rsize)
1165 		server->rsize = nfs_io_size(ctx->rsize, server->nfs_client->cl_proto);
1166 	if (ctx->wsize)
1167 		server->wsize = nfs_io_size(ctx->wsize, server->nfs_client->cl_proto);
1168 
1169 	server->acregmin = ctx->acregmin * HZ;
1170 	server->acregmax = ctx->acregmax * HZ;
1171 	server->acdirmin = ctx->acdirmin * HZ;
1172 	server->acdirmax = ctx->acdirmax * HZ;
1173 	server->port     = ctx->nfs_server.port;
1174 
1175 	return nfs_init_server_rpcclient(server, &timeparms,
1176 					 ctx->selected_flavor);
1177 }
1178 
1179 /*
1180  * Create a version 4 volume record
1181  * - keyed on server and FSID
1182  */
1183 struct nfs_server *nfs4_create_server(struct fs_context *fc)
1184 {
1185 	struct nfs_fs_context *ctx = nfs_fc2context(fc);
1186 	struct nfs_server *server;
1187 	bool auth_probe;
1188 	int error;
1189 
1190 	server = nfs_alloc_server();
1191 	if (!server)
1192 		return ERR_PTR(-ENOMEM);
1193 
1194 	server->cred = get_cred(fc->cred);
1195 
1196 	auth_probe = ctx->auth_info.flavor_len < 1;
1197 
1198 	/* set up the general RPC client */
1199 	error = nfs4_init_server(server, fc);
1200 	if (error < 0)
1201 		goto error;
1202 
1203 	error = nfs4_server_common_setup(server, ctx->mntfh, auth_probe);
1204 	if (error < 0)
1205 		goto error;
1206 
1207 	return server;
1208 
1209 error:
1210 	nfs_free_server(server);
1211 	return ERR_PTR(error);
1212 }
1213 
1214 /*
1215  * Create an NFS4 referral server record
1216  */
1217 struct nfs_server *nfs4_create_referral_server(struct fs_context *fc)
1218 {
1219 	struct nfs_fs_context *ctx = nfs_fc2context(fc);
1220 	struct nfs_client *parent_client;
1221 	struct nfs_server *server, *parent_server;
1222 	bool auth_probe;
1223 	int error;
1224 
1225 	server = nfs_alloc_server();
1226 	if (!server)
1227 		return ERR_PTR(-ENOMEM);
1228 
1229 	parent_server = NFS_SB(ctx->clone_data.sb);
1230 	parent_client = parent_server->nfs_client;
1231 
1232 	server->cred = get_cred(parent_server->cred);
1233 
1234 	/* Initialise the client representation from the parent server */
1235 	nfs_server_copy_userdata(server, parent_server);
1236 
1237 	/* Get a client representation */
1238 #if IS_ENABLED(CONFIG_SUNRPC_XPRT_RDMA)
1239 	rpc_set_port(&ctx->nfs_server.address, NFS_RDMA_PORT);
1240 	error = nfs4_set_client(server,
1241 				ctx->nfs_server.hostname,
1242 				&ctx->nfs_server._address,
1243 				ctx->nfs_server.addrlen,
1244 				parent_client->cl_ipaddr,
1245 				XPRT_TRANSPORT_RDMA,
1246 				parent_server->client->cl_timeout,
1247 				parent_client->cl_mvops->minor_version,
1248 				parent_client->cl_nconnect,
1249 				parent_client->cl_max_connect,
1250 				parent_client->cl_net);
1251 	if (!error)
1252 		goto init_server;
1253 #endif	/* IS_ENABLED(CONFIG_SUNRPC_XPRT_RDMA) */
1254 
1255 	rpc_set_port(&ctx->nfs_server.address, NFS_PORT);
1256 	error = nfs4_set_client(server,
1257 				ctx->nfs_server.hostname,
1258 				&ctx->nfs_server._address,
1259 				ctx->nfs_server.addrlen,
1260 				parent_client->cl_ipaddr,
1261 				XPRT_TRANSPORT_TCP,
1262 				parent_server->client->cl_timeout,
1263 				parent_client->cl_mvops->minor_version,
1264 				parent_client->cl_nconnect,
1265 				parent_client->cl_max_connect,
1266 				parent_client->cl_net);
1267 	if (error < 0)
1268 		goto error;
1269 
1270 #if IS_ENABLED(CONFIG_SUNRPC_XPRT_RDMA)
1271 init_server:
1272 #endif
1273 	error = nfs_init_server_rpcclient(server, parent_server->client->cl_timeout,
1274 					  ctx->selected_flavor);
1275 	if (error < 0)
1276 		goto error;
1277 
1278 	auth_probe = parent_server->auth_info.flavor_len < 1;
1279 
1280 	error = nfs4_server_common_setup(server, ctx->mntfh, auth_probe);
1281 	if (error < 0)
1282 		goto error;
1283 
1284 	return server;
1285 
1286 error:
1287 	nfs_free_server(server);
1288 	return ERR_PTR(error);
1289 }
1290 
1291 /**
1292  * nfs4_update_server - Move an nfs_server to a different nfs_client
1293  *
1294  * @server: represents FSID to be moved
1295  * @hostname: new end-point's hostname
1296  * @sap: new end-point's socket address
1297  * @salen: size of "sap"
1298  * @net: net namespace
1299  *
1300  * The nfs_server must be quiescent before this function is invoked.
1301  * Either its session is drained (NFSv4.1+), or its transport is
1302  * plugged and drained (NFSv4.0).
1303  *
1304  * Returns zero on success, or a negative errno value.
1305  */
1306 int nfs4_update_server(struct nfs_server *server, const char *hostname,
1307 		       struct sockaddr_storage *sap, size_t salen, struct net *net)
1308 {
1309 	struct nfs_client *clp = server->nfs_client;
1310 	struct rpc_clnt *clnt = server->client;
1311 	struct xprt_create xargs = {
1312 		.ident		= clp->cl_proto,
1313 		.net		= net,
1314 		.dstaddr	= (struct sockaddr *)sap,
1315 		.addrlen	= salen,
1316 		.servername	= hostname,
1317 	};
1318 	char buf[INET6_ADDRSTRLEN + 1];
1319 	struct sockaddr_storage address;
1320 	struct sockaddr *localaddr = (struct sockaddr *)&address;
1321 	int error;
1322 
1323 	error = rpc_switch_client_transport(clnt, &xargs, clnt->cl_timeout);
1324 	if (error != 0)
1325 		return error;
1326 
1327 	error = rpc_localaddr(clnt, localaddr, sizeof(address));
1328 	if (error != 0)
1329 		return error;
1330 
1331 	if (rpc_ntop(localaddr, buf, sizeof(buf)) == 0)
1332 		return -EAFNOSUPPORT;
1333 
1334 	nfs_server_remove_lists(server);
1335 	set_bit(NFS_MIG_TSM_POSSIBLE, &server->mig_status);
1336 	error = nfs4_set_client(server, hostname, sap, salen, buf,
1337 				clp->cl_proto, clnt->cl_timeout,
1338 				clp->cl_minorversion,
1339 				clp->cl_nconnect, clp->cl_max_connect, net);
1340 	clear_bit(NFS_MIG_TSM_POSSIBLE, &server->mig_status);
1341 	if (error != 0) {
1342 		nfs_server_insert_lists(server);
1343 		return error;
1344 	}
1345 	nfs_put_client(clp);
1346 
1347 	if (server->nfs_client->cl_hostname == NULL) {
1348 		server->nfs_client->cl_hostname = kstrdup(hostname, GFP_KERNEL);
1349 		if (server->nfs_client->cl_hostname == NULL)
1350 			return -ENOMEM;
1351 	}
1352 	nfs_server_insert_lists(server);
1353 
1354 	return nfs_probe_server(server, NFS_FH(d_inode(server->super->s_root)));
1355 }
1356