xref: /linux/fs/nfs/super.c (revision 409c38d4f156740bf3165fd6ceae4fa6425eebf4)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  linux/fs/nfs/super.c
4  *
5  *  Copyright (C) 1992  Rick Sladkey
6  *
7  *  nfs superblock handling functions
8  *
9  *  Modularised by Alan Cox <alan@lxorguk.ukuu.org.uk>, while hacking some
10  *  experimental NFS changes. Modularisation taken straight from SYS5 fs.
11  *
12  *  Change to nfs_read_super() to permit NFS mounts to multi-homed hosts.
13  *  J.S.Peatfield@damtp.cam.ac.uk
14  *
15  *  Split from inode.c by David Howells <dhowells@redhat.com>
16  *
17  * - superblocks are indexed on server only - all inodes, dentries, etc. associated with a
18  *   particular server are held in the same superblock
19  * - NFS superblocks can have several effective roots to the dentry tree
20  * - directory type roots are spliced into the tree when a path from one root reaches the root
21  *   of another (see nfs_lookup())
22  */
23 
24 #include <linux/module.h>
25 #include <linux/init.h>
26 
27 #include <linux/time.h>
28 #include <linux/kernel.h>
29 #include <linux/mm.h>
30 #include <linux/string.h>
31 #include <linux/stat.h>
32 #include <linux/errno.h>
33 #include <linux/unistd.h>
34 #include <linux/sunrpc/clnt.h>
35 #include <linux/sunrpc/addr.h>
36 #include <linux/sunrpc/stats.h>
37 #include <linux/sunrpc/metrics.h>
38 #include <linux/sunrpc/xprtsock.h>
39 #include <linux/sunrpc/xprtrdma.h>
40 #include <linux/nfs_fs.h>
41 #include <linux/nfs_mount.h>
42 #include <linux/nfs4_mount.h>
43 #include <linux/lockd/bind.h>
44 #include <linux/seq_file.h>
45 #include <linux/mount.h>
46 #include <linux/namei.h>
47 #include <linux/vfs.h>
48 #include <linux/inet.h>
49 #include <linux/in6.h>
50 #include <linux/slab.h>
51 #include <net/ipv6.h>
52 #include <linux/netdevice.h>
53 #include <linux/nfs_xdr.h>
54 #include <linux/magic.h>
55 #include <linux/parser.h>
56 #include <linux/nsproxy.h>
57 #include <linux/rcupdate.h>
58 
59 #include <linux/uaccess.h>
60 #include <linux/nfs_ssc.h>
61 
62 #include <uapi/linux/tls.h>
63 
64 #include "nfs4_fs.h"
65 #include "callback.h"
66 #include "delegation.h"
67 #include "iostat.h"
68 #include "internal.h"
69 #include "fscache.h"
70 #include "nfs4session.h"
71 #include "pnfs.h"
72 #include "nfs.h"
73 #include "netns.h"
74 #include "sysfs.h"
75 
76 #define NFSDBG_FACILITY		NFSDBG_VFS
77 
78 const struct super_operations nfs_sops = {
79 	.alloc_inode	= nfs_alloc_inode,
80 	.free_inode	= nfs_free_inode,
81 	.write_inode	= nfs_write_inode,
82 	.drop_inode	= nfs_drop_inode,
83 	.statfs		= nfs_statfs,
84 	.evict_inode	= nfs_evict_inode,
85 	.umount_begin	= nfs_umount_begin,
86 	.show_options	= nfs_show_options,
87 	.show_devname	= nfs_show_devname,
88 	.show_path	= nfs_show_path,
89 	.show_stats	= nfs_show_stats,
90 };
91 EXPORT_SYMBOL_GPL(nfs_sops);
92 
93 #ifdef CONFIG_NFS_V4_2
94 static const struct nfs_ssc_client_ops nfs_ssc_clnt_ops_tbl = {
95 	.sco_sb_deactive = nfs_sb_deactive,
96 };
97 #endif
98 
99 #if IS_ENABLED(CONFIG_NFS_V4)
100 static int __init register_nfs4_fs(void)
101 {
102 	return register_filesystem(&nfs4_fs_type);
103 }
104 
105 static void unregister_nfs4_fs(void)
106 {
107 	unregister_filesystem(&nfs4_fs_type);
108 }
109 #else
110 static int __init register_nfs4_fs(void)
111 {
112 	return 0;
113 }
114 
115 static void unregister_nfs4_fs(void)
116 {
117 }
118 #endif
119 
120 #ifdef CONFIG_NFS_V4_2
121 static void nfs_ssc_register_ops(void)
122 {
123 	nfs_ssc_register(&nfs_ssc_clnt_ops_tbl);
124 }
125 
126 static void nfs_ssc_unregister_ops(void)
127 {
128 	nfs_ssc_unregister(&nfs_ssc_clnt_ops_tbl);
129 }
130 #endif /* CONFIG_NFS_V4_2 */
131 
132 static struct shrinker *acl_shrinker;
133 
134 /*
135  * Register the NFS filesystems
136  */
137 int __init register_nfs_fs(void)
138 {
139 	int ret;
140 
141         ret = register_filesystem(&nfs_fs_type);
142 	if (ret < 0)
143 		goto error_0;
144 
145 	ret = register_nfs4_fs();
146 	if (ret < 0)
147 		goto error_1;
148 
149 	ret = nfs_register_sysctl();
150 	if (ret < 0)
151 		goto error_2;
152 
153 	acl_shrinker = shrinker_alloc(0, "nfs-acl");
154 	if (!acl_shrinker) {
155 		ret = -ENOMEM;
156 		goto error_3;
157 	}
158 
159 	acl_shrinker->count_objects = nfs_access_cache_count;
160 	acl_shrinker->scan_objects = nfs_access_cache_scan;
161 
162 	shrinker_register(acl_shrinker);
163 
164 #ifdef CONFIG_NFS_V4_2
165 	nfs_ssc_register_ops();
166 #endif
167 	return 0;
168 error_3:
169 	nfs_unregister_sysctl();
170 error_2:
171 	unregister_nfs4_fs();
172 error_1:
173 	unregister_filesystem(&nfs_fs_type);
174 error_0:
175 	return ret;
176 }
177 
178 /*
179  * Unregister the NFS filesystems
180  */
181 void __exit unregister_nfs_fs(void)
182 {
183 	shrinker_free(acl_shrinker);
184 	nfs_unregister_sysctl();
185 	unregister_nfs4_fs();
186 #ifdef CONFIG_NFS_V4_2
187 	nfs_ssc_unregister_ops();
188 #endif
189 	unregister_filesystem(&nfs_fs_type);
190 }
191 
192 bool nfs_sb_active(struct super_block *sb)
193 {
194 	struct nfs_server *server = NFS_SB(sb);
195 
196 	if (!atomic_inc_not_zero(&sb->s_active))
197 		return false;
198 	if (atomic_inc_return(&server->active) != 1)
199 		atomic_dec(&sb->s_active);
200 	return true;
201 }
202 EXPORT_SYMBOL_GPL(nfs_sb_active);
203 
204 void nfs_sb_deactive(struct super_block *sb)
205 {
206 	struct nfs_server *server = NFS_SB(sb);
207 
208 	if (atomic_dec_and_test(&server->active))
209 		deactivate_super(sb);
210 }
211 EXPORT_SYMBOL_GPL(nfs_sb_deactive);
212 
213 static int __nfs_list_for_each_server(struct list_head *head,
214 		int (*fn)(struct nfs_server *, void *),
215 		void *data)
216 {
217 	struct nfs_server *server, *last = NULL;
218 	int ret = 0;
219 
220 	rcu_read_lock();
221 	list_for_each_entry_rcu(server, head, client_link) {
222 		if (!(server->super && nfs_sb_active(server->super)))
223 			continue;
224 		rcu_read_unlock();
225 		if (last)
226 			nfs_sb_deactive(last->super);
227 		last = server;
228 		ret = fn(server, data);
229 		if (ret)
230 			goto out;
231 		rcu_read_lock();
232 	}
233 	rcu_read_unlock();
234 out:
235 	if (last)
236 		nfs_sb_deactive(last->super);
237 	return ret;
238 }
239 
240 int nfs_client_for_each_server(struct nfs_client *clp,
241 		int (*fn)(struct nfs_server *, void *),
242 		void *data)
243 {
244 	return __nfs_list_for_each_server(&clp->cl_superblocks, fn, data);
245 }
246 EXPORT_SYMBOL_GPL(nfs_client_for_each_server);
247 
248 /*
249  * Deliver file system statistics to userspace
250  */
251 int nfs_statfs(struct dentry *dentry, struct kstatfs *buf)
252 {
253 	struct nfs_server *server = NFS_SB(dentry->d_sb);
254 	unsigned char blockbits;
255 	unsigned long blockres;
256 	struct nfs_fh *fh = NFS_FH(d_inode(dentry));
257 	struct nfs_fsstat res;
258 	int error = -ENOMEM;
259 
260 	res.fattr = nfs_alloc_fattr();
261 	if (res.fattr == NULL)
262 		goto out_err;
263 
264 	error = server->nfs_client->rpc_ops->statfs(server, fh, &res);
265 	if (unlikely(error == -ESTALE)) {
266 		struct dentry *pd_dentry;
267 
268 		pd_dentry = dget_parent(dentry);
269 		nfs_zap_caches(d_inode(pd_dentry));
270 		dput(pd_dentry);
271 	}
272 	nfs_free_fattr(res.fattr);
273 	if (error < 0)
274 		goto out_err;
275 
276 	buf->f_type = NFS_SUPER_MAGIC;
277 
278 	/*
279 	 * Current versions of glibc do not correctly handle the
280 	 * case where f_frsize != f_bsize.  Eventually we want to
281 	 * report the value of wtmult in this field.
282 	 */
283 	buf->f_frsize = dentry->d_sb->s_blocksize;
284 
285 	/*
286 	 * On most *nix systems, f_blocks, f_bfree, and f_bavail
287 	 * are reported in units of f_frsize.  Linux hasn't had
288 	 * an f_frsize field in its statfs struct until recently,
289 	 * thus historically Linux's sys_statfs reports these
290 	 * fields in units of f_bsize.
291 	 */
292 	buf->f_bsize = dentry->d_sb->s_blocksize;
293 	blockbits = dentry->d_sb->s_blocksize_bits;
294 	blockres = (1 << blockbits) - 1;
295 	buf->f_blocks = (res.tbytes + blockres) >> blockbits;
296 	buf->f_bfree = (res.fbytes + blockres) >> blockbits;
297 	buf->f_bavail = (res.abytes + blockres) >> blockbits;
298 
299 	buf->f_files = res.tfiles;
300 	buf->f_ffree = res.afiles;
301 
302 	buf->f_namelen = server->namelen;
303 
304 	return 0;
305 
306  out_err:
307 	dprintk("%s: statfs error = %d\n", __func__, -error);
308 	return error;
309 }
310 EXPORT_SYMBOL_GPL(nfs_statfs);
311 
312 /*
313  * Map the security flavour number to a name
314  */
315 static const char *nfs_pseudoflavour_to_name(rpc_authflavor_t flavour)
316 {
317 	static const struct {
318 		rpc_authflavor_t flavour;
319 		const char *str;
320 	} sec_flavours[NFS_AUTH_INFO_MAX_FLAVORS] = {
321 		/* update NFS_AUTH_INFO_MAX_FLAVORS when this list changes! */
322 		{ RPC_AUTH_NULL, "null" },
323 		{ RPC_AUTH_UNIX, "sys" },
324 		{ RPC_AUTH_GSS_KRB5, "krb5" },
325 		{ RPC_AUTH_GSS_KRB5I, "krb5i" },
326 		{ RPC_AUTH_GSS_KRB5P, "krb5p" },
327 		{ RPC_AUTH_GSS_LKEY, "lkey" },
328 		{ RPC_AUTH_GSS_LKEYI, "lkeyi" },
329 		{ RPC_AUTH_GSS_LKEYP, "lkeyp" },
330 		{ RPC_AUTH_GSS_SPKM, "spkm" },
331 		{ RPC_AUTH_GSS_SPKMI, "spkmi" },
332 		{ RPC_AUTH_GSS_SPKMP, "spkmp" },
333 		{ UINT_MAX, "unknown" }
334 	};
335 	int i;
336 
337 	for (i = 0; sec_flavours[i].flavour != UINT_MAX; i++) {
338 		if (sec_flavours[i].flavour == flavour)
339 			break;
340 	}
341 	return sec_flavours[i].str;
342 }
343 
344 static void nfs_show_mountd_netid(struct seq_file *m, struct nfs_server *nfss,
345 				  int showdefaults)
346 {
347 	struct sockaddr *sap = (struct sockaddr *) &nfss->mountd_address;
348 	char *proto = NULL;
349 
350 	switch (sap->sa_family) {
351 	case AF_INET:
352 		switch (nfss->mountd_protocol) {
353 		case IPPROTO_UDP:
354 			proto = RPCBIND_NETID_UDP;
355 			break;
356 		case IPPROTO_TCP:
357 			proto = RPCBIND_NETID_TCP;
358 			break;
359 		}
360 		break;
361 	case AF_INET6:
362 		switch (nfss->mountd_protocol) {
363 		case IPPROTO_UDP:
364 			proto = RPCBIND_NETID_UDP6;
365 			break;
366 		case IPPROTO_TCP:
367 			proto = RPCBIND_NETID_TCP6;
368 			break;
369 		}
370 		break;
371 	}
372 	if (proto || showdefaults)
373 		seq_printf(m, ",mountproto=%s", proto ?: "auto");
374 }
375 
376 static void nfs_show_mountd_options(struct seq_file *m, struct nfs_server *nfss,
377 				    int showdefaults)
378 {
379 	struct sockaddr *sap = (struct sockaddr *)&nfss->mountd_address;
380 
381 	if (nfss->flags & NFS_MOUNT_LEGACY_INTERFACE)
382 		return;
383 
384 	switch (sap->sa_family) {
385 	case AF_INET: {
386 		struct sockaddr_in *sin = (struct sockaddr_in *)sap;
387 		seq_printf(m, ",mountaddr=%pI4", &sin->sin_addr.s_addr);
388 		break;
389 	}
390 	case AF_INET6: {
391 		struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sap;
392 		seq_printf(m, ",mountaddr=%pI6c", &sin6->sin6_addr);
393 		break;
394 	}
395 	default:
396 		if (showdefaults)
397 			seq_puts(m, ",mountaddr=unspecified");
398 	}
399 
400 	if (nfss->mountd_version || showdefaults)
401 		seq_printf(m, ",mountvers=%u", nfss->mountd_version);
402 	if ((nfss->mountd_port &&
403 		nfss->mountd_port != (unsigned short)NFS_UNSPEC_PORT) ||
404 		showdefaults)
405 		seq_printf(m, ",mountport=%u", nfss->mountd_port);
406 
407 	nfs_show_mountd_netid(m, nfss, showdefaults);
408 }
409 
410 #if IS_ENABLED(CONFIG_NFS_V4)
411 static void nfs_show_nfsv4_options(struct seq_file *m, struct nfs_server *nfss,
412 				    int showdefaults)
413 {
414 	struct nfs_client *clp = nfss->nfs_client;
415 
416 	seq_printf(m, ",clientaddr=%s", clp->cl_ipaddr);
417 }
418 #else
419 static void nfs_show_nfsv4_options(struct seq_file *m, struct nfs_server *nfss,
420 				    int showdefaults)
421 {
422 }
423 #endif
424 
425 static void nfs_show_nfs_version(struct seq_file *m,
426 		unsigned int version,
427 		unsigned int minorversion)
428 {
429 	seq_printf(m, ",vers=%u", version);
430 	if (version == 4)
431 		seq_printf(m, ".%u", minorversion);
432 }
433 
434 /*
435  * Describe the mount options in force on this server representation
436  */
437 static void nfs_show_mount_options(struct seq_file *m, struct nfs_server *nfss,
438 				   int showdefaults)
439 {
440 	static const struct proc_nfs_info {
441 		int flag;
442 		const char *str;
443 		const char *nostr;
444 	} nfs_info[] = {
445 		{ NFS_MOUNT_SOFT, ",soft", "" },
446 		{ NFS_MOUNT_SOFTERR, ",softerr", "" },
447 		{ NFS_MOUNT_SOFTREVAL, ",softreval", "" },
448 		{ NFS_MOUNT_POSIX, ",posix", "" },
449 		{ NFS_MOUNT_NOCTO, ",nocto", "" },
450 		{ NFS_MOUNT_NOAC, ",noac", "" },
451 		{ NFS_MOUNT_NONLM, ",nolock", "" },
452 		{ NFS_MOUNT_NOACL, ",noacl", "" },
453 		{ NFS_MOUNT_NORDIRPLUS, ",nordirplus", "" },
454 		{ NFS_MOUNT_UNSHARED, ",nosharecache", "" },
455 		{ NFS_MOUNT_NORESVPORT, ",noresvport", "" },
456 		{ 0, NULL, NULL }
457 	};
458 	const struct proc_nfs_info *nfs_infop;
459 	struct nfs_client *clp = nfss->nfs_client;
460 	u32 version = clp->rpc_ops->version;
461 	int local_flock, local_fcntl;
462 
463 	nfs_show_nfs_version(m, version, clp->cl_minorversion);
464 	seq_printf(m, ",rsize=%u", nfss->rsize);
465 	seq_printf(m, ",wsize=%u", nfss->wsize);
466 	if (nfss->bsize != 0)
467 		seq_printf(m, ",bsize=%u", nfss->bsize);
468 	seq_printf(m, ",namlen=%u", nfss->namelen);
469 	if (nfss->acregmin != NFS_DEF_ACREGMIN*HZ || showdefaults)
470 		seq_printf(m, ",acregmin=%u", nfss->acregmin/HZ);
471 	if (nfss->acregmax != NFS_DEF_ACREGMAX*HZ || showdefaults)
472 		seq_printf(m, ",acregmax=%u", nfss->acregmax/HZ);
473 	if (nfss->acdirmin != NFS_DEF_ACDIRMIN*HZ || showdefaults)
474 		seq_printf(m, ",acdirmin=%u", nfss->acdirmin/HZ);
475 	if (nfss->acdirmax != NFS_DEF_ACDIRMAX*HZ || showdefaults)
476 		seq_printf(m, ",acdirmax=%u", nfss->acdirmax/HZ);
477 	if (!(nfss->flags & (NFS_MOUNT_SOFT|NFS_MOUNT_SOFTERR)))
478 			seq_puts(m, ",hard");
479 	for (nfs_infop = nfs_info; nfs_infop->flag; nfs_infop++) {
480 		if (nfss->flags & nfs_infop->flag)
481 			seq_puts(m, nfs_infop->str);
482 		else
483 			seq_puts(m, nfs_infop->nostr);
484 	}
485 	rcu_read_lock();
486 	seq_printf(m, ",proto=%s",
487 		   rpc_peeraddr2str(nfss->client, RPC_DISPLAY_NETID));
488 	rcu_read_unlock();
489 	if (clp->cl_nconnect > 0)
490 		seq_printf(m, ",nconnect=%u", clp->cl_nconnect);
491 	if (version == 4) {
492 		if (clp->cl_max_connect > 1)
493 			seq_printf(m, ",max_connect=%u", clp->cl_max_connect);
494 		if (nfss->port != NFS_PORT)
495 			seq_printf(m, ",port=%u", nfss->port);
496 	} else
497 		if (nfss->port)
498 			seq_printf(m, ",port=%u", nfss->port);
499 
500 	seq_printf(m, ",timeo=%lu", 10U * nfss->client->cl_timeout->to_initval / HZ);
501 	seq_printf(m, ",retrans=%u", nfss->client->cl_timeout->to_retries);
502 	seq_printf(m, ",sec=%s", nfs_pseudoflavour_to_name(nfss->client->cl_auth->au_flavor));
503 	switch (clp->cl_xprtsec.policy) {
504 	case RPC_XPRTSEC_TLS_ANON:
505 		seq_puts(m, ",xprtsec=tls");
506 		break;
507 	case RPC_XPRTSEC_TLS_X509:
508 		seq_puts(m, ",xprtsec=mtls");
509 		break;
510 	default:
511 		break;
512 	}
513 
514 	if (version != 4)
515 		nfs_show_mountd_options(m, nfss, showdefaults);
516 	else
517 		nfs_show_nfsv4_options(m, nfss, showdefaults);
518 
519 	if (nfss->options & NFS_OPTION_FSCACHE)
520 		seq_puts(m, ",fsc");
521 
522 	if (nfss->options & NFS_OPTION_MIGRATION)
523 		seq_puts(m, ",migration");
524 
525 	if (nfss->flags & NFS_MOUNT_LOOKUP_CACHE_NONEG) {
526 		if (nfss->flags & NFS_MOUNT_LOOKUP_CACHE_NONE)
527 			seq_puts(m, ",lookupcache=none");
528 		else
529 			seq_puts(m, ",lookupcache=pos");
530 	}
531 
532 	local_flock = nfss->flags & NFS_MOUNT_LOCAL_FLOCK;
533 	local_fcntl = nfss->flags & NFS_MOUNT_LOCAL_FCNTL;
534 
535 	if (!local_flock && !local_fcntl)
536 		seq_puts(m, ",local_lock=none");
537 	else if (local_flock && local_fcntl)
538 		seq_puts(m, ",local_lock=all");
539 	else if (local_flock)
540 		seq_puts(m, ",local_lock=flock");
541 	else
542 		seq_puts(m, ",local_lock=posix");
543 
544 	if (nfss->flags & NFS_MOUNT_WRITE_EAGER) {
545 		if (nfss->flags & NFS_MOUNT_WRITE_WAIT)
546 			seq_puts(m, ",write=wait");
547 		else
548 			seq_puts(m, ",write=eager");
549 	}
550 }
551 
552 /*
553  * Describe the mount options on this VFS mountpoint
554  */
555 int nfs_show_options(struct seq_file *m, struct dentry *root)
556 {
557 	struct nfs_server *nfss = NFS_SB(root->d_sb);
558 
559 	nfs_show_mount_options(m, nfss, 0);
560 
561 	rcu_read_lock();
562 	seq_printf(m, ",addr=%s",
563 			rpc_peeraddr2str(nfss->nfs_client->cl_rpcclient,
564 							RPC_DISPLAY_ADDR));
565 	rcu_read_unlock();
566 
567 	return 0;
568 }
569 EXPORT_SYMBOL_GPL(nfs_show_options);
570 
571 #if IS_ENABLED(CONFIG_NFS_V4)
572 static void show_lease(struct seq_file *m, struct nfs_server *server)
573 {
574 	struct nfs_client *clp = server->nfs_client;
575 	unsigned long expire;
576 
577 	seq_printf(m, ",lease_time=%ld", clp->cl_lease_time / HZ);
578 	expire = clp->cl_last_renewal + clp->cl_lease_time;
579 	seq_printf(m, ",lease_expired=%ld",
580 		   time_after(expire, jiffies) ?  0 : (jiffies - expire) / HZ);
581 }
582 #ifdef CONFIG_NFS_V4_1
583 static void show_sessions(struct seq_file *m, struct nfs_server *server)
584 {
585 	if (nfs4_has_session(server->nfs_client))
586 		seq_puts(m, ",sessions");
587 }
588 #else
589 static void show_sessions(struct seq_file *m, struct nfs_server *server) {}
590 #endif
591 #endif
592 
593 #ifdef CONFIG_NFS_V4_1
594 static void show_pnfs(struct seq_file *m, struct nfs_server *server)
595 {
596 	seq_printf(m, ",pnfs=");
597 	if (server->pnfs_curr_ld)
598 		seq_printf(m, "%s", server->pnfs_curr_ld->name);
599 	else
600 		seq_printf(m, "not configured");
601 }
602 
603 static void show_implementation_id(struct seq_file *m, struct nfs_server *nfss)
604 {
605 	if (nfss->nfs_client && nfss->nfs_client->cl_implid) {
606 		struct nfs41_impl_id *impl_id = nfss->nfs_client->cl_implid;
607 		seq_printf(m, "\n\timpl_id:\tname='%s',domain='%s',"
608 			   "date='%llu,%u'",
609 			   impl_id->name, impl_id->domain,
610 			   impl_id->date.seconds, impl_id->date.nseconds);
611 	}
612 }
613 #else
614 #if IS_ENABLED(CONFIG_NFS_V4)
615 static void show_pnfs(struct seq_file *m, struct nfs_server *server)
616 {
617 }
618 #endif
619 static void show_implementation_id(struct seq_file *m, struct nfs_server *nfss)
620 {
621 }
622 #endif
623 
624 int nfs_show_devname(struct seq_file *m, struct dentry *root)
625 {
626 	char *page = (char *) __get_free_page(GFP_KERNEL);
627 	char *devname, *dummy;
628 	int err = 0;
629 	if (!page)
630 		return -ENOMEM;
631 	devname = nfs_path(&dummy, root, page, PAGE_SIZE, 0);
632 	if (IS_ERR(devname))
633 		err = PTR_ERR(devname);
634 	else
635 		seq_escape(m, devname, " \t\n\\");
636 	free_page((unsigned long)page);
637 	return err;
638 }
639 EXPORT_SYMBOL_GPL(nfs_show_devname);
640 
641 int nfs_show_path(struct seq_file *m, struct dentry *dentry)
642 {
643 	seq_puts(m, "/");
644 	return 0;
645 }
646 EXPORT_SYMBOL_GPL(nfs_show_path);
647 
648 /*
649  * Present statistical information for this VFS mountpoint
650  */
651 int nfs_show_stats(struct seq_file *m, struct dentry *root)
652 {
653 	int i, cpu;
654 	struct nfs_server *nfss = NFS_SB(root->d_sb);
655 	struct rpc_auth *auth = nfss->client->cl_auth;
656 	struct nfs_iostats totals = { };
657 
658 	seq_printf(m, "statvers=%s", NFS_IOSTAT_VERS);
659 
660 	/*
661 	 * Display all mount option settings
662 	 */
663 	seq_puts(m, "\n\topts:\t");
664 	seq_puts(m, sb_rdonly(root->d_sb) ? "ro" : "rw");
665 	seq_puts(m, root->d_sb->s_flags & SB_SYNCHRONOUS ? ",sync" : "");
666 	seq_puts(m, root->d_sb->s_flags & SB_NOATIME ? ",noatime" : "");
667 	seq_puts(m, root->d_sb->s_flags & SB_NODIRATIME ? ",nodiratime" : "");
668 	nfs_show_mount_options(m, nfss, 1);
669 
670 	seq_printf(m, "\n\tage:\t%lu", (jiffies - nfss->mount_time) / HZ);
671 
672 	show_implementation_id(m, nfss);
673 
674 	seq_puts(m, "\n\tcaps:\t");
675 	seq_printf(m, "caps=0x%x", nfss->caps);
676 	seq_printf(m, ",wtmult=%u", nfss->wtmult);
677 	seq_printf(m, ",dtsize=%u", nfss->dtsize);
678 	seq_printf(m, ",bsize=%u", nfss->bsize);
679 	seq_printf(m, ",namlen=%u", nfss->namelen);
680 
681 #if IS_ENABLED(CONFIG_NFS_V4)
682 	if (nfss->nfs_client->rpc_ops->version == 4) {
683 		seq_puts(m, "\n\tnfsv4:\t");
684 		seq_printf(m, "bm0=0x%x", nfss->attr_bitmask[0]);
685 		seq_printf(m, ",bm1=0x%x", nfss->attr_bitmask[1]);
686 		seq_printf(m, ",bm2=0x%x", nfss->attr_bitmask[2]);
687 		seq_printf(m, ",acl=0x%x", nfss->acl_bitmask);
688 		show_sessions(m, nfss);
689 		show_pnfs(m, nfss);
690 		show_lease(m, nfss);
691 	}
692 #endif
693 
694 	/*
695 	 * Display security flavor in effect for this mount
696 	 */
697 	seq_printf(m, "\n\tsec:\tflavor=%u", auth->au_ops->au_flavor);
698 	if (auth->au_flavor)
699 		seq_printf(m, ",pseudoflavor=%u", auth->au_flavor);
700 
701 	/*
702 	 * Display superblock I/O counters
703 	 */
704 	for_each_possible_cpu(cpu) {
705 		struct nfs_iostats *stats;
706 
707 		preempt_disable();
708 		stats = per_cpu_ptr(nfss->io_stats, cpu);
709 
710 		for (i = 0; i < __NFSIOS_COUNTSMAX; i++)
711 			totals.events[i] += stats->events[i];
712 		for (i = 0; i < __NFSIOS_BYTESMAX; i++)
713 			totals.bytes[i] += stats->bytes[i];
714 
715 		preempt_enable();
716 	}
717 
718 	seq_puts(m, "\n\tevents:\t");
719 	for (i = 0; i < __NFSIOS_COUNTSMAX; i++)
720 		seq_printf(m, "%lu ", totals.events[i]);
721 	seq_puts(m, "\n\tbytes:\t");
722 	for (i = 0; i < __NFSIOS_BYTESMAX; i++)
723 		seq_printf(m, "%Lu ", totals.bytes[i]);
724 	seq_putc(m, '\n');
725 
726 	rpc_clnt_show_stats(m, nfss->client);
727 
728 	return 0;
729 }
730 EXPORT_SYMBOL_GPL(nfs_show_stats);
731 
732 /*
733  * Begin unmount by attempting to remove all automounted mountpoints we added
734  * in response to xdev traversals and referrals
735  */
736 void nfs_umount_begin(struct super_block *sb)
737 {
738 	struct nfs_server *server;
739 	struct rpc_clnt *rpc;
740 
741 	server = NFS_SB(sb);
742 	/* -EIO all pending I/O */
743 	rpc = server->client_acl;
744 	if (!IS_ERR(rpc))
745 		rpc_killall_tasks(rpc);
746 	rpc = server->client;
747 	if (!IS_ERR(rpc))
748 		rpc_killall_tasks(rpc);
749 }
750 EXPORT_SYMBOL_GPL(nfs_umount_begin);
751 
752 /*
753  * Return true if 'match' is in auth_info or auth_info is empty.
754  * Return false otherwise.
755  */
756 bool nfs_auth_info_match(const struct nfs_auth_info *auth_info,
757 			 rpc_authflavor_t match)
758 {
759 	int i;
760 
761 	if (!auth_info->flavor_len)
762 		return true;
763 
764 	for (i = 0; i < auth_info->flavor_len; i++) {
765 		if (auth_info->flavors[i] == match)
766 			return true;
767 	}
768 	return false;
769 }
770 EXPORT_SYMBOL_GPL(nfs_auth_info_match);
771 
772 /*
773  * Ensure that a specified authtype in ctx->auth_info is supported by
774  * the server. Returns 0 and sets ctx->selected_flavor if it's ok, and
775  * -EACCES if not.
776  */
777 static int nfs_verify_authflavors(struct nfs_fs_context *ctx,
778 				  rpc_authflavor_t *server_authlist,
779 				  unsigned int count)
780 {
781 	rpc_authflavor_t flavor = RPC_AUTH_MAXFLAVOR;
782 	bool found_auth_null = false;
783 	unsigned int i;
784 
785 	/*
786 	 * If the sec= mount option is used, the specified flavor or AUTH_NULL
787 	 * must be in the list returned by the server.
788 	 *
789 	 * AUTH_NULL has a special meaning when it's in the server list - it
790 	 * means that the server will ignore the rpc creds, so any flavor
791 	 * can be used but still use the sec= that was specified.
792 	 *
793 	 * Note also that the MNT procedure in MNTv1 does not return a list
794 	 * of supported security flavors. In this case, nfs_mount() fabricates
795 	 * a security flavor list containing just AUTH_NULL.
796 	 */
797 	for (i = 0; i < count; i++) {
798 		flavor = server_authlist[i];
799 
800 		if (nfs_auth_info_match(&ctx->auth_info, flavor))
801 			goto out;
802 
803 		if (flavor == RPC_AUTH_NULL)
804 			found_auth_null = true;
805 	}
806 
807 	if (found_auth_null) {
808 		flavor = ctx->auth_info.flavors[0];
809 		goto out;
810 	}
811 
812 	dfprintk(MOUNT,
813 		 "NFS: specified auth flavors not supported by server\n");
814 	return -EACCES;
815 
816 out:
817 	ctx->selected_flavor = flavor;
818 	dfprintk(MOUNT, "NFS: using auth flavor %u\n", ctx->selected_flavor);
819 	return 0;
820 }
821 
822 /*
823  * Use the remote server's MOUNT service to request the NFS file handle
824  * corresponding to the provided path.
825  */
826 static int nfs_request_mount(struct fs_context *fc,
827 			     struct nfs_fh *root_fh,
828 			     rpc_authflavor_t *server_authlist,
829 			     unsigned int *server_authlist_len)
830 {
831 	struct nfs_fs_context *ctx = nfs_fc2context(fc);
832 	struct nfs_mount_request request = {
833 		.sap		= &ctx->mount_server._address,
834 		.dirpath	= ctx->nfs_server.export_path,
835 		.protocol	= ctx->mount_server.protocol,
836 		.fh		= root_fh,
837 		.noresvport	= ctx->flags & NFS_MOUNT_NORESVPORT,
838 		.auth_flav_len	= server_authlist_len,
839 		.auth_flavs	= server_authlist,
840 		.net		= fc->net_ns,
841 	};
842 	int status;
843 
844 	if (ctx->mount_server.version == 0) {
845 		switch (ctx->version) {
846 			default:
847 				ctx->mount_server.version = NFS_MNT3_VERSION;
848 				break;
849 			case 2:
850 				ctx->mount_server.version = NFS_MNT_VERSION;
851 		}
852 	}
853 	request.version = ctx->mount_server.version;
854 
855 	if (ctx->mount_server.hostname)
856 		request.hostname = ctx->mount_server.hostname;
857 	else
858 		request.hostname = ctx->nfs_server.hostname;
859 
860 	/*
861 	 * Construct the mount server's address.
862 	 */
863 	if (ctx->mount_server.address.sa_family == AF_UNSPEC) {
864 		memcpy(request.sap, &ctx->nfs_server._address,
865 		       ctx->nfs_server.addrlen);
866 		ctx->mount_server.addrlen = ctx->nfs_server.addrlen;
867 	}
868 	request.salen = ctx->mount_server.addrlen;
869 	nfs_set_port(request.sap, &ctx->mount_server.port, 0);
870 
871 	/*
872 	 * Now ask the mount server to map our export path
873 	 * to a file handle.
874 	 */
875 	status = nfs_mount(&request, ctx->timeo, ctx->retrans);
876 	if (status != 0) {
877 		dfprintk(MOUNT, "NFS: unable to mount server %s, error %d\n",
878 				request.hostname, status);
879 		return status;
880 	}
881 
882 	return 0;
883 }
884 
885 static struct nfs_server *nfs_try_mount_request(struct fs_context *fc)
886 {
887 	struct nfs_fs_context *ctx = nfs_fc2context(fc);
888 	int status;
889 	unsigned int i;
890 	bool tried_auth_unix = false;
891 	bool auth_null_in_list = false;
892 	struct nfs_server *server = ERR_PTR(-EACCES);
893 	rpc_authflavor_t authlist[NFS_MAX_SECFLAVORS];
894 	unsigned int authlist_len = ARRAY_SIZE(authlist);
895 
896 	status = nfs_request_mount(fc, ctx->mntfh, authlist, &authlist_len);
897 	if (status)
898 		return ERR_PTR(status);
899 
900 	/*
901 	 * Was a sec= authflavor specified in the options? First, verify
902 	 * whether the server supports it, and then just try to use it if so.
903 	 */
904 	if (ctx->auth_info.flavor_len > 0) {
905 		status = nfs_verify_authflavors(ctx, authlist, authlist_len);
906 		dfprintk(MOUNT, "NFS: using auth flavor %u\n",
907 			 ctx->selected_flavor);
908 		if (status)
909 			return ERR_PTR(status);
910 		return ctx->nfs_mod->rpc_ops->create_server(fc);
911 	}
912 
913 	/*
914 	 * No sec= option was provided. RFC 2623, section 2.7 suggests we
915 	 * SHOULD prefer the flavor listed first. However, some servers list
916 	 * AUTH_NULL first. Avoid ever choosing AUTH_NULL.
917 	 */
918 	for (i = 0; i < authlist_len; ++i) {
919 		rpc_authflavor_t flavor;
920 		struct rpcsec_gss_info info;
921 
922 		flavor = authlist[i];
923 		switch (flavor) {
924 		case RPC_AUTH_UNIX:
925 			tried_auth_unix = true;
926 			break;
927 		case RPC_AUTH_NULL:
928 			auth_null_in_list = true;
929 			continue;
930 		default:
931 			if (rpcauth_get_gssinfo(flavor, &info) != 0)
932 				continue;
933 			break;
934 		}
935 		dfprintk(MOUNT, "NFS: attempting to use auth flavor %u\n", flavor);
936 		ctx->selected_flavor = flavor;
937 		server = ctx->nfs_mod->rpc_ops->create_server(fc);
938 		if (!IS_ERR(server))
939 			return server;
940 	}
941 
942 	/*
943 	 * Nothing we tried so far worked. At this point, give up if we've
944 	 * already tried AUTH_UNIX or if the server's list doesn't contain
945 	 * AUTH_NULL
946 	 */
947 	if (tried_auth_unix || !auth_null_in_list)
948 		return server;
949 
950 	/* Last chance! Try AUTH_UNIX */
951 	dfprintk(MOUNT, "NFS: attempting to use auth flavor %u\n", RPC_AUTH_UNIX);
952 	ctx->selected_flavor = RPC_AUTH_UNIX;
953 	return ctx->nfs_mod->rpc_ops->create_server(fc);
954 }
955 
956 int nfs_try_get_tree(struct fs_context *fc)
957 {
958 	struct nfs_fs_context *ctx = nfs_fc2context(fc);
959 
960 	if (ctx->need_mount)
961 		ctx->server = nfs_try_mount_request(fc);
962 	else
963 		ctx->server = ctx->nfs_mod->rpc_ops->create_server(fc);
964 
965 	return nfs_get_tree_common(fc);
966 }
967 EXPORT_SYMBOL_GPL(nfs_try_get_tree);
968 
969 
970 #define NFS_REMOUNT_CMP_FLAGMASK ~(NFS_MOUNT_INTR \
971 		| NFS_MOUNT_SECURE \
972 		| NFS_MOUNT_TCP \
973 		| NFS_MOUNT_VER3 \
974 		| NFS_MOUNT_KERBEROS \
975 		| NFS_MOUNT_NONLM \
976 		| NFS_MOUNT_BROKEN_SUID \
977 		| NFS_MOUNT_STRICTLOCK \
978 		| NFS_MOUNT_LEGACY_INTERFACE)
979 
980 #define NFS_MOUNT_CMP_FLAGMASK (NFS_REMOUNT_CMP_FLAGMASK & \
981 		~(NFS_MOUNT_UNSHARED | NFS_MOUNT_NORESVPORT))
982 
983 static int
984 nfs_compare_remount_data(struct nfs_server *nfss,
985 			 struct nfs_fs_context *ctx)
986 {
987 	if ((ctx->flags ^ nfss->flags) & NFS_REMOUNT_CMP_FLAGMASK ||
988 	    ctx->rsize != nfss->rsize ||
989 	    ctx->wsize != nfss->wsize ||
990 	    ctx->version != nfss->nfs_client->rpc_ops->version ||
991 	    ctx->minorversion != nfss->nfs_client->cl_minorversion ||
992 	    ctx->retrans != nfss->client->cl_timeout->to_retries ||
993 	    !nfs_auth_info_match(&ctx->auth_info, nfss->client->cl_auth->au_flavor) ||
994 	    ctx->acregmin != nfss->acregmin / HZ ||
995 	    ctx->acregmax != nfss->acregmax / HZ ||
996 	    ctx->acdirmin != nfss->acdirmin / HZ ||
997 	    ctx->acdirmax != nfss->acdirmax / HZ ||
998 	    ctx->timeo != (10U * nfss->client->cl_timeout->to_initval / HZ) ||
999 	    (ctx->options & NFS_OPTION_FSCACHE) != (nfss->options & NFS_OPTION_FSCACHE) ||
1000 	    ctx->nfs_server.port != nfss->port ||
1001 	    ctx->nfs_server.addrlen != nfss->nfs_client->cl_addrlen ||
1002 	    !rpc_cmp_addr((struct sockaddr *)&ctx->nfs_server.address,
1003 			  (struct sockaddr *)&nfss->nfs_client->cl_addr))
1004 		return -EINVAL;
1005 
1006 	return 0;
1007 }
1008 
1009 int nfs_reconfigure(struct fs_context *fc)
1010 {
1011 	struct nfs_fs_context *ctx = nfs_fc2context(fc);
1012 	struct super_block *sb = fc->root->d_sb;
1013 	struct nfs_server *nfss = sb->s_fs_info;
1014 	int ret;
1015 
1016 	sync_filesystem(sb);
1017 
1018 	/*
1019 	 * Userspace mount programs that send binary options generally send
1020 	 * them populated with default values. We have no way to know which
1021 	 * ones were explicitly specified. Fall back to legacy behavior and
1022 	 * just return success.
1023 	 */
1024 	if (ctx->skip_reconfig_option_check)
1025 		return 0;
1026 
1027 	/*
1028 	 * noac is a special case. It implies -o sync, but that's not
1029 	 * necessarily reflected in the mtab options. reconfigure_super
1030 	 * will clear SB_SYNCHRONOUS if -o sync wasn't specified in the
1031 	 * remount options, so we have to explicitly reset it.
1032 	 */
1033 	if (ctx->flags & NFS_MOUNT_NOAC) {
1034 		fc->sb_flags |= SB_SYNCHRONOUS;
1035 		fc->sb_flags_mask |= SB_SYNCHRONOUS;
1036 	}
1037 
1038 	/* compare new mount options with old ones */
1039 	ret = nfs_compare_remount_data(nfss, ctx);
1040 	if (ret)
1041 		return ret;
1042 
1043 	return nfs_probe_server(nfss, NFS_FH(d_inode(fc->root)));
1044 }
1045 EXPORT_SYMBOL_GPL(nfs_reconfigure);
1046 
1047 /*
1048  * Finish setting up an NFS superblock
1049  */
1050 static void nfs_fill_super(struct super_block *sb, struct nfs_fs_context *ctx)
1051 {
1052 	struct nfs_server *server = NFS_SB(sb);
1053 
1054 	sb->s_blocksize_bits = 0;
1055 	sb->s_blocksize = 0;
1056 	sb->s_xattr = server->nfs_client->cl_nfs_mod->xattr;
1057 	sb->s_op = server->nfs_client->cl_nfs_mod->sops;
1058 	if (ctx->bsize)
1059 		sb->s_blocksize = nfs_block_size(ctx->bsize, &sb->s_blocksize_bits);
1060 
1061 	switch (server->nfs_client->rpc_ops->version) {
1062 	case 2:
1063 		sb->s_time_gran = 1000;
1064 		sb->s_time_min = 0;
1065 		sb->s_time_max = U32_MAX;
1066 		break;
1067 	case 3:
1068 		/*
1069 		 * The VFS shouldn't apply the umask to mode bits.
1070 		 * We will do so ourselves when necessary.
1071 		 */
1072 		sb->s_flags |= SB_POSIXACL;
1073 		sb->s_time_gran = 1;
1074 		sb->s_time_min = 0;
1075 		sb->s_time_max = U32_MAX;
1076 		sb->s_export_op = &nfs_export_ops;
1077 		break;
1078 	case 4:
1079 		sb->s_iflags |= SB_I_NOUMASK;
1080 		sb->s_time_gran = 1;
1081 		sb->s_time_min = S64_MIN;
1082 		sb->s_time_max = S64_MAX;
1083 		if (server->caps & NFS_CAP_ATOMIC_OPEN_V1)
1084 			sb->s_export_op = &nfs_export_ops;
1085 		break;
1086 	}
1087 
1088 	sb->s_magic = NFS_SUPER_MAGIC;
1089 
1090 	/* We probably want something more informative here */
1091 	snprintf(sb->s_id, sizeof(sb->s_id),
1092 		 "%u:%u", MAJOR(sb->s_dev), MINOR(sb->s_dev));
1093 
1094 	if (sb->s_blocksize == 0)
1095 		sb->s_blocksize = nfs_block_bits(server->wsize,
1096 						 &sb->s_blocksize_bits);
1097 
1098 	nfs_super_set_maxbytes(sb, server->maxfilesize);
1099 	nfs_sysfs_move_server_to_sb(sb);
1100 	server->has_sec_mnt_opts = ctx->has_sec_mnt_opts;
1101 }
1102 
1103 static int nfs_compare_mount_options(const struct super_block *s, const struct nfs_server *b,
1104 				     const struct fs_context *fc)
1105 {
1106 	const struct nfs_server *a = s->s_fs_info;
1107 	const struct rpc_clnt *clnt_a = a->client;
1108 	const struct rpc_clnt *clnt_b = b->client;
1109 
1110 	if ((s->s_flags & NFS_SB_MASK) != (fc->sb_flags & NFS_SB_MASK))
1111 		goto Ebusy;
1112 	if (a->nfs_client != b->nfs_client)
1113 		goto Ebusy;
1114 	if ((a->flags ^ b->flags) & NFS_MOUNT_CMP_FLAGMASK)
1115 		goto Ebusy;
1116 	if (a->wsize != b->wsize)
1117 		goto Ebusy;
1118 	if (a->rsize != b->rsize)
1119 		goto Ebusy;
1120 	if (a->acregmin != b->acregmin)
1121 		goto Ebusy;
1122 	if (a->acregmax != b->acregmax)
1123 		goto Ebusy;
1124 	if (a->acdirmin != b->acdirmin)
1125 		goto Ebusy;
1126 	if (a->acdirmax != b->acdirmax)
1127 		goto Ebusy;
1128 	if (clnt_a->cl_auth->au_flavor != clnt_b->cl_auth->au_flavor)
1129 		goto Ebusy;
1130 	return 1;
1131 Ebusy:
1132 	return 0;
1133 }
1134 
1135 static int nfs_set_super(struct super_block *s, struct fs_context *fc)
1136 {
1137 	struct nfs_server *server = fc->s_fs_info;
1138 	int ret;
1139 
1140 	s->s_d_op = server->nfs_client->rpc_ops->dentry_ops;
1141 	ret = set_anon_super(s, server);
1142 	if (ret == 0)
1143 		server->s_dev = s->s_dev;
1144 	return ret;
1145 }
1146 
1147 static int nfs_compare_super_address(struct nfs_server *server1,
1148 				     struct nfs_server *server2)
1149 {
1150 	struct sockaddr *sap1, *sap2;
1151 	struct rpc_xprt *xprt1 = server1->client->cl_xprt;
1152 	struct rpc_xprt *xprt2 = server2->client->cl_xprt;
1153 
1154 	if (!net_eq(xprt1->xprt_net, xprt2->xprt_net))
1155 		return 0;
1156 
1157 	sap1 = (struct sockaddr *)&server1->nfs_client->cl_addr;
1158 	sap2 = (struct sockaddr *)&server2->nfs_client->cl_addr;
1159 
1160 	if (sap1->sa_family != sap2->sa_family)
1161 		return 0;
1162 
1163 	switch (sap1->sa_family) {
1164 	case AF_INET: {
1165 		struct sockaddr_in *sin1 = (struct sockaddr_in *)sap1;
1166 		struct sockaddr_in *sin2 = (struct sockaddr_in *)sap2;
1167 		if (sin1->sin_addr.s_addr != sin2->sin_addr.s_addr)
1168 			return 0;
1169 		if (sin1->sin_port != sin2->sin_port)
1170 			return 0;
1171 		break;
1172 	}
1173 	case AF_INET6: {
1174 		struct sockaddr_in6 *sin1 = (struct sockaddr_in6 *)sap1;
1175 		struct sockaddr_in6 *sin2 = (struct sockaddr_in6 *)sap2;
1176 		if (!ipv6_addr_equal(&sin1->sin6_addr, &sin2->sin6_addr))
1177 			return 0;
1178 		if (sin1->sin6_port != sin2->sin6_port)
1179 			return 0;
1180 		break;
1181 	}
1182 	default:
1183 		return 0;
1184 	}
1185 
1186 	return 1;
1187 }
1188 
1189 static int nfs_compare_userns(const struct nfs_server *old,
1190 		const struct nfs_server *new)
1191 {
1192 	const struct user_namespace *oldns = &init_user_ns;
1193 	const struct user_namespace *newns = &init_user_ns;
1194 
1195 	if (old->client && old->client->cl_cred)
1196 		oldns = old->client->cl_cred->user_ns;
1197 	if (new->client && new->client->cl_cred)
1198 		newns = new->client->cl_cred->user_ns;
1199 	if (oldns != newns)
1200 		return 0;
1201 	return 1;
1202 }
1203 
1204 static int nfs_compare_super(struct super_block *sb, struct fs_context *fc)
1205 {
1206 	struct nfs_server *server = fc->s_fs_info, *old = NFS_SB(sb);
1207 
1208 	if (!nfs_compare_super_address(old, server))
1209 		return 0;
1210 	/* Note: NFS_MOUNT_UNSHARED == NFS4_MOUNT_UNSHARED */
1211 	if (old->flags & NFS_MOUNT_UNSHARED)
1212 		return 0;
1213 	if (memcmp(&old->fsid, &server->fsid, sizeof(old->fsid)) != 0)
1214 		return 0;
1215 	if (!nfs_compare_userns(old, server))
1216 		return 0;
1217 	if ((old->has_sec_mnt_opts || fc->security) &&
1218 			security_sb_mnt_opts_compat(sb, fc->security))
1219 		return 0;
1220 	return nfs_compare_mount_options(sb, server, fc);
1221 }
1222 
1223 #ifdef CONFIG_NFS_FSCACHE
1224 static int nfs_get_cache_cookie(struct super_block *sb,
1225 				struct nfs_fs_context *ctx)
1226 {
1227 	struct nfs_server *nfss = NFS_SB(sb);
1228 	char *uniq = NULL;
1229 	int ulen = 0;
1230 
1231 	nfss->fscache = NULL;
1232 
1233 	if (!ctx)
1234 		return 0;
1235 
1236 	if (ctx->clone_data.sb) {
1237 		struct nfs_server *mnt_s = NFS_SB(ctx->clone_data.sb);
1238 		if (!(mnt_s->options & NFS_OPTION_FSCACHE))
1239 			return 0;
1240 		if (mnt_s->fscache_uniq) {
1241 			uniq = mnt_s->fscache_uniq;
1242 			ulen = strlen(uniq);
1243 		}
1244 	} else {
1245 		if (!(ctx->options & NFS_OPTION_FSCACHE))
1246 			return 0;
1247 		if (ctx->fscache_uniq) {
1248 			uniq = ctx->fscache_uniq;
1249 			ulen = strlen(ctx->fscache_uniq);
1250 		}
1251 	}
1252 
1253 	return nfs_fscache_get_super_cookie(sb, uniq, ulen);
1254 }
1255 #else
1256 static int nfs_get_cache_cookie(struct super_block *sb,
1257 				struct nfs_fs_context *ctx)
1258 {
1259 	return 0;
1260 }
1261 #endif
1262 
1263 int nfs_get_tree_common(struct fs_context *fc)
1264 {
1265 	struct nfs_fs_context *ctx = nfs_fc2context(fc);
1266 	struct super_block *s;
1267 	int (*compare_super)(struct super_block *, struct fs_context *) = nfs_compare_super;
1268 	struct nfs_server *server = ctx->server;
1269 	int error;
1270 
1271 	ctx->server = NULL;
1272 	if (IS_ERR(server))
1273 		return PTR_ERR(server);
1274 
1275 	if (server->flags & NFS_MOUNT_UNSHARED)
1276 		compare_super = NULL;
1277 
1278 	/* -o noac implies -o sync */
1279 	if (server->flags & NFS_MOUNT_NOAC)
1280 		fc->sb_flags |= SB_SYNCHRONOUS;
1281 
1282 	if (ctx->clone_data.sb)
1283 		if (ctx->clone_data.sb->s_flags & SB_SYNCHRONOUS)
1284 			fc->sb_flags |= SB_SYNCHRONOUS;
1285 
1286 	/* Get a superblock - note that we may end up sharing one that already exists */
1287 	fc->s_fs_info = server;
1288 	s = sget_fc(fc, compare_super, nfs_set_super);
1289 	fc->s_fs_info = NULL;
1290 	if (IS_ERR(s)) {
1291 		error = PTR_ERR(s);
1292 		nfs_errorf(fc, "NFS: Couldn't get superblock");
1293 		goto out_err_nosb;
1294 	}
1295 
1296 	if (s->s_fs_info != server) {
1297 		nfs_free_server(server);
1298 		server = NULL;
1299 	} else {
1300 		error = super_setup_bdi_name(s, "%u:%u", MAJOR(server->s_dev),
1301 					     MINOR(server->s_dev));
1302 		if (error)
1303 			goto error_splat_super;
1304 		s->s_bdi->io_pages = server->rpages;
1305 		server->super = s;
1306 	}
1307 
1308 	if (!s->s_root) {
1309 		unsigned bsize = ctx->clone_data.inherited_bsize;
1310 		/* initial superblock/root creation */
1311 		nfs_fill_super(s, ctx);
1312 		if (bsize) {
1313 			s->s_blocksize_bits = bsize;
1314 			s->s_blocksize = 1U << bsize;
1315 		}
1316 		error = nfs_get_cache_cookie(s, ctx);
1317 		if (error < 0)
1318 			goto error_splat_super;
1319 	}
1320 
1321 	error = nfs_get_root(s, fc);
1322 	if (error < 0) {
1323 		nfs_errorf(fc, "NFS: Couldn't get root dentry");
1324 		goto error_splat_super;
1325 	}
1326 
1327 	s->s_flags |= SB_ACTIVE;
1328 	error = 0;
1329 
1330 out:
1331 	return error;
1332 
1333 out_err_nosb:
1334 	nfs_free_server(server);
1335 	goto out;
1336 error_splat_super:
1337 	deactivate_locked_super(s);
1338 	goto out;
1339 }
1340 
1341 /*
1342  * Destroy an NFS superblock
1343  */
1344 void nfs_kill_super(struct super_block *s)
1345 {
1346 	struct nfs_server *server = NFS_SB(s);
1347 
1348 	nfs_sysfs_move_sb_to_server(server);
1349 	kill_anon_super(s);
1350 
1351 	nfs_fscache_release_super_cookie(s);
1352 
1353 	nfs_free_server(server);
1354 }
1355 EXPORT_SYMBOL_GPL(nfs_kill_super);
1356 
1357 #if IS_ENABLED(CONFIG_NFS_V4)
1358 
1359 /*
1360  * NFS v4 module parameters need to stay in the
1361  * NFS client for backwards compatibility
1362  */
1363 unsigned int nfs_callback_set_tcpport;
1364 unsigned short nfs_callback_nr_threads;
1365 /* Default cache timeout is 10 minutes */
1366 unsigned int nfs_idmap_cache_timeout = 600;
1367 /* Turn off NFSv4 uid/gid mapping when using AUTH_SYS */
1368 bool nfs4_disable_idmapping = true;
1369 unsigned short max_session_slots = NFS4_DEF_SLOT_TABLE_SIZE;
1370 unsigned short max_session_cb_slots = NFS4_DEF_CB_SLOT_TABLE_SIZE;
1371 unsigned short send_implementation_id = 1;
1372 char nfs4_client_id_uniquifier[NFS4_CLIENT_ID_UNIQ_LEN] = "";
1373 bool recover_lost_locks = false;
1374 short nfs_delay_retrans = -1;
1375 
1376 EXPORT_SYMBOL_GPL(nfs_callback_nr_threads);
1377 EXPORT_SYMBOL_GPL(nfs_callback_set_tcpport);
1378 EXPORT_SYMBOL_GPL(nfs_idmap_cache_timeout);
1379 EXPORT_SYMBOL_GPL(nfs4_disable_idmapping);
1380 EXPORT_SYMBOL_GPL(max_session_slots);
1381 EXPORT_SYMBOL_GPL(max_session_cb_slots);
1382 EXPORT_SYMBOL_GPL(send_implementation_id);
1383 EXPORT_SYMBOL_GPL(nfs4_client_id_uniquifier);
1384 EXPORT_SYMBOL_GPL(recover_lost_locks);
1385 EXPORT_SYMBOL_GPL(nfs_delay_retrans);
1386 
1387 #define NFS_CALLBACK_MAXPORTNR (65535U)
1388 
1389 static int param_set_portnr(const char *val, const struct kernel_param *kp)
1390 {
1391 	unsigned long num;
1392 	int ret;
1393 
1394 	if (!val)
1395 		return -EINVAL;
1396 	ret = kstrtoul(val, 0, &num);
1397 	if (ret || num > NFS_CALLBACK_MAXPORTNR)
1398 		return -EINVAL;
1399 	*((unsigned int *)kp->arg) = num;
1400 	return 0;
1401 }
1402 static const struct kernel_param_ops param_ops_portnr = {
1403 	.set = param_set_portnr,
1404 	.get = param_get_uint,
1405 };
1406 #define param_check_portnr(name, p) __param_check(name, p, unsigned int)
1407 
1408 module_param_named(callback_tcpport, nfs_callback_set_tcpport, portnr, 0644);
1409 module_param_named(callback_nr_threads, nfs_callback_nr_threads, ushort, 0644);
1410 MODULE_PARM_DESC(callback_nr_threads, "Number of threads that will be "
1411 		"assigned to the NFSv4 callback channels.");
1412 module_param(nfs_idmap_cache_timeout, int, 0644);
1413 module_param(nfs4_disable_idmapping, bool, 0644);
1414 module_param_string(nfs4_unique_id, nfs4_client_id_uniquifier,
1415 			NFS4_CLIENT_ID_UNIQ_LEN, 0600);
1416 MODULE_PARM_DESC(nfs4_disable_idmapping,
1417 		"Turn off NFSv4 idmapping when using 'sec=sys'");
1418 module_param(max_session_slots, ushort, 0644);
1419 MODULE_PARM_DESC(max_session_slots, "Maximum number of outstanding NFSv4.1 "
1420 		"requests the client will negotiate");
1421 module_param(max_session_cb_slots, ushort, 0644);
1422 MODULE_PARM_DESC(max_session_cb_slots, "Maximum number of parallel NFSv4.1 "
1423 		"callbacks the client will process for a given server");
1424 module_param(send_implementation_id, ushort, 0644);
1425 MODULE_PARM_DESC(send_implementation_id,
1426 		"Send implementation ID with NFSv4.1 exchange_id");
1427 MODULE_PARM_DESC(nfs4_unique_id, "nfs_client_id4 uniquifier string");
1428 
1429 module_param(recover_lost_locks, bool, 0644);
1430 MODULE_PARM_DESC(recover_lost_locks,
1431 		 "If the server reports that a lock might be lost, "
1432 		 "try to recover it risking data corruption.");
1433 
1434 module_param_named(delay_retrans, nfs_delay_retrans, short, 0644);
1435 MODULE_PARM_DESC(delay_retrans,
1436 		 "Unless negative, specifies the number of times the NFSv4 "
1437 		 "client retries a request before returning an EAGAIN error, "
1438 		 "after a reply of NFS4ERR_DELAY from the server.");
1439 #endif /* CONFIG_NFS_V4 */
1440