xref: /linux/fs/nfs/super.c (revision ba6e0e5cb5b2c2e736e16b4aead816450a8718e6)
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 	.count_objects	= nfs_access_cache_count,
134 	.scan_objects	= nfs_access_cache_scan,
135 	.seeks		= DEFAULT_SEEKS,
136 };
137 
138 /*
139  * Register the NFS filesystems
140  */
141 int __init register_nfs_fs(void)
142 {
143 	int ret;
144 
145         ret = register_filesystem(&nfs_fs_type);
146 	if (ret < 0)
147 		goto error_0;
148 
149 	ret = register_nfs4_fs();
150 	if (ret < 0)
151 		goto error_1;
152 
153 	ret = nfs_register_sysctl();
154 	if (ret < 0)
155 		goto error_2;
156 	ret = register_shrinker(&acl_shrinker, "nfs-acl");
157 	if (ret < 0)
158 		goto error_3;
159 #ifdef CONFIG_NFS_V4_2
160 	nfs_ssc_register_ops();
161 #endif
162 	return 0;
163 error_3:
164 	nfs_unregister_sysctl();
165 error_2:
166 	unregister_nfs4_fs();
167 error_1:
168 	unregister_filesystem(&nfs_fs_type);
169 error_0:
170 	return ret;
171 }
172 
173 /*
174  * Unregister the NFS filesystems
175  */
176 void __exit unregister_nfs_fs(void)
177 {
178 	unregister_shrinker(&acl_shrinker);
179 	nfs_unregister_sysctl();
180 	unregister_nfs4_fs();
181 #ifdef CONFIG_NFS_V4_2
182 	nfs_ssc_unregister_ops();
183 #endif
184 	unregister_filesystem(&nfs_fs_type);
185 }
186 
187 bool nfs_sb_active(struct super_block *sb)
188 {
189 	struct nfs_server *server = NFS_SB(sb);
190 
191 	if (!atomic_inc_not_zero(&sb->s_active))
192 		return false;
193 	if (atomic_inc_return(&server->active) != 1)
194 		atomic_dec(&sb->s_active);
195 	return true;
196 }
197 EXPORT_SYMBOL_GPL(nfs_sb_active);
198 
199 void nfs_sb_deactive(struct super_block *sb)
200 {
201 	struct nfs_server *server = NFS_SB(sb);
202 
203 	if (atomic_dec_and_test(&server->active))
204 		deactivate_super(sb);
205 }
206 EXPORT_SYMBOL_GPL(nfs_sb_deactive);
207 
208 static int __nfs_list_for_each_server(struct list_head *head,
209 		int (*fn)(struct nfs_server *, void *),
210 		void *data)
211 {
212 	struct nfs_server *server, *last = NULL;
213 	int ret = 0;
214 
215 	rcu_read_lock();
216 	list_for_each_entry_rcu(server, head, client_link) {
217 		if (!(server->super && nfs_sb_active(server->super)))
218 			continue;
219 		rcu_read_unlock();
220 		if (last)
221 			nfs_sb_deactive(last->super);
222 		last = server;
223 		ret = fn(server, data);
224 		if (ret)
225 			goto out;
226 		rcu_read_lock();
227 	}
228 	rcu_read_unlock();
229 out:
230 	if (last)
231 		nfs_sb_deactive(last->super);
232 	return ret;
233 }
234 
235 int nfs_client_for_each_server(struct nfs_client *clp,
236 		int (*fn)(struct nfs_server *, void *),
237 		void *data)
238 {
239 	return __nfs_list_for_each_server(&clp->cl_superblocks, fn, data);
240 }
241 EXPORT_SYMBOL_GPL(nfs_client_for_each_server);
242 
243 /*
244  * Deliver file system statistics to userspace
245  */
246 int nfs_statfs(struct dentry *dentry, struct kstatfs *buf)
247 {
248 	struct nfs_server *server = NFS_SB(dentry->d_sb);
249 	unsigned char blockbits;
250 	unsigned long blockres;
251 	struct nfs_fh *fh = NFS_FH(d_inode(dentry));
252 	struct nfs_fsstat res;
253 	int error = -ENOMEM;
254 
255 	res.fattr = nfs_alloc_fattr();
256 	if (res.fattr == NULL)
257 		goto out_err;
258 
259 	error = server->nfs_client->rpc_ops->statfs(server, fh, &res);
260 	if (unlikely(error == -ESTALE)) {
261 		struct dentry *pd_dentry;
262 
263 		pd_dentry = dget_parent(dentry);
264 		nfs_zap_caches(d_inode(pd_dentry));
265 		dput(pd_dentry);
266 	}
267 	nfs_free_fattr(res.fattr);
268 	if (error < 0)
269 		goto out_err;
270 
271 	buf->f_type = NFS_SUPER_MAGIC;
272 
273 	/*
274 	 * Current versions of glibc do not correctly handle the
275 	 * case where f_frsize != f_bsize.  Eventually we want to
276 	 * report the value of wtmult in this field.
277 	 */
278 	buf->f_frsize = dentry->d_sb->s_blocksize;
279 
280 	/*
281 	 * On most *nix systems, f_blocks, f_bfree, and f_bavail
282 	 * are reported in units of f_frsize.  Linux hasn't had
283 	 * an f_frsize field in its statfs struct until recently,
284 	 * thus historically Linux's sys_statfs reports these
285 	 * fields in units of f_bsize.
286 	 */
287 	buf->f_bsize = dentry->d_sb->s_blocksize;
288 	blockbits = dentry->d_sb->s_blocksize_bits;
289 	blockres = (1 << blockbits) - 1;
290 	buf->f_blocks = (res.tbytes + blockres) >> blockbits;
291 	buf->f_bfree = (res.fbytes + blockres) >> blockbits;
292 	buf->f_bavail = (res.abytes + blockres) >> blockbits;
293 
294 	buf->f_files = res.tfiles;
295 	buf->f_ffree = res.afiles;
296 
297 	buf->f_namelen = server->namelen;
298 
299 	return 0;
300 
301  out_err:
302 	dprintk("%s: statfs error = %d\n", __func__, -error);
303 	return error;
304 }
305 EXPORT_SYMBOL_GPL(nfs_statfs);
306 
307 /*
308  * Map the security flavour number to a name
309  */
310 static const char *nfs_pseudoflavour_to_name(rpc_authflavor_t flavour)
311 {
312 	static const struct {
313 		rpc_authflavor_t flavour;
314 		const char *str;
315 	} sec_flavours[NFS_AUTH_INFO_MAX_FLAVORS] = {
316 		/* update NFS_AUTH_INFO_MAX_FLAVORS when this list changes! */
317 		{ RPC_AUTH_NULL, "null" },
318 		{ RPC_AUTH_UNIX, "sys" },
319 		{ RPC_AUTH_GSS_KRB5, "krb5" },
320 		{ RPC_AUTH_GSS_KRB5I, "krb5i" },
321 		{ RPC_AUTH_GSS_KRB5P, "krb5p" },
322 		{ RPC_AUTH_GSS_LKEY, "lkey" },
323 		{ RPC_AUTH_GSS_LKEYI, "lkeyi" },
324 		{ RPC_AUTH_GSS_LKEYP, "lkeyp" },
325 		{ RPC_AUTH_GSS_SPKM, "spkm" },
326 		{ RPC_AUTH_GSS_SPKMI, "spkmi" },
327 		{ RPC_AUTH_GSS_SPKMP, "spkmp" },
328 		{ UINT_MAX, "unknown" }
329 	};
330 	int i;
331 
332 	for (i = 0; sec_flavours[i].flavour != UINT_MAX; i++) {
333 		if (sec_flavours[i].flavour == flavour)
334 			break;
335 	}
336 	return sec_flavours[i].str;
337 }
338 
339 static void nfs_show_mountd_netid(struct seq_file *m, struct nfs_server *nfss,
340 				  int showdefaults)
341 {
342 	struct sockaddr *sap = (struct sockaddr *) &nfss->mountd_address;
343 	char *proto = NULL;
344 
345 	switch (sap->sa_family) {
346 	case AF_INET:
347 		switch (nfss->mountd_protocol) {
348 		case IPPROTO_UDP:
349 			proto = RPCBIND_NETID_UDP;
350 			break;
351 		case IPPROTO_TCP:
352 			proto = RPCBIND_NETID_TCP;
353 			break;
354 		}
355 		break;
356 	case AF_INET6:
357 		switch (nfss->mountd_protocol) {
358 		case IPPROTO_UDP:
359 			proto = RPCBIND_NETID_UDP6;
360 			break;
361 		case IPPROTO_TCP:
362 			proto = RPCBIND_NETID_TCP6;
363 			break;
364 		}
365 		break;
366 	}
367 	if (proto || showdefaults)
368 		seq_printf(m, ",mountproto=%s", proto ?: "auto");
369 }
370 
371 static void nfs_show_mountd_options(struct seq_file *m, struct nfs_server *nfss,
372 				    int showdefaults)
373 {
374 	struct sockaddr *sap = (struct sockaddr *)&nfss->mountd_address;
375 
376 	if (nfss->flags & NFS_MOUNT_LEGACY_INTERFACE)
377 		return;
378 
379 	switch (sap->sa_family) {
380 	case AF_INET: {
381 		struct sockaddr_in *sin = (struct sockaddr_in *)sap;
382 		seq_printf(m, ",mountaddr=%pI4", &sin->sin_addr.s_addr);
383 		break;
384 	}
385 	case AF_INET6: {
386 		struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sap;
387 		seq_printf(m, ",mountaddr=%pI6c", &sin6->sin6_addr);
388 		break;
389 	}
390 	default:
391 		if (showdefaults)
392 			seq_puts(m, ",mountaddr=unspecified");
393 	}
394 
395 	if (nfss->mountd_version || showdefaults)
396 		seq_printf(m, ",mountvers=%u", nfss->mountd_version);
397 	if ((nfss->mountd_port &&
398 		nfss->mountd_port != (unsigned short)NFS_UNSPEC_PORT) ||
399 		showdefaults)
400 		seq_printf(m, ",mountport=%u", nfss->mountd_port);
401 
402 	nfs_show_mountd_netid(m, nfss, showdefaults);
403 }
404 
405 #if IS_ENABLED(CONFIG_NFS_V4)
406 static void nfs_show_nfsv4_options(struct seq_file *m, struct nfs_server *nfss,
407 				    int showdefaults)
408 {
409 	struct nfs_client *clp = nfss->nfs_client;
410 
411 	seq_printf(m, ",clientaddr=%s", clp->cl_ipaddr);
412 }
413 #else
414 static void nfs_show_nfsv4_options(struct seq_file *m, struct nfs_server *nfss,
415 				    int showdefaults)
416 {
417 }
418 #endif
419 
420 static void nfs_show_nfs_version(struct seq_file *m,
421 		unsigned int version,
422 		unsigned int minorversion)
423 {
424 	seq_printf(m, ",vers=%u", version);
425 	if (version == 4)
426 		seq_printf(m, ".%u", minorversion);
427 }
428 
429 /*
430  * Describe the mount options in force on this server representation
431  */
432 static void nfs_show_mount_options(struct seq_file *m, struct nfs_server *nfss,
433 				   int showdefaults)
434 {
435 	static const struct proc_nfs_info {
436 		int flag;
437 		const char *str;
438 		const char *nostr;
439 	} nfs_info[] = {
440 		{ NFS_MOUNT_SOFT, ",soft", "" },
441 		{ NFS_MOUNT_SOFTERR, ",softerr", "" },
442 		{ NFS_MOUNT_SOFTREVAL, ",softreval", "" },
443 		{ NFS_MOUNT_POSIX, ",posix", "" },
444 		{ NFS_MOUNT_NOCTO, ",nocto", "" },
445 		{ NFS_MOUNT_NOAC, ",noac", "" },
446 		{ NFS_MOUNT_NONLM, ",nolock", "" },
447 		{ NFS_MOUNT_NOACL, ",noacl", "" },
448 		{ NFS_MOUNT_NORDIRPLUS, ",nordirplus", "" },
449 		{ NFS_MOUNT_UNSHARED, ",nosharecache", "" },
450 		{ NFS_MOUNT_NORESVPORT, ",noresvport", "" },
451 		{ 0, NULL, NULL }
452 	};
453 	const struct proc_nfs_info *nfs_infop;
454 	struct nfs_client *clp = nfss->nfs_client;
455 	u32 version = clp->rpc_ops->version;
456 	int local_flock, local_fcntl;
457 
458 	nfs_show_nfs_version(m, version, clp->cl_minorversion);
459 	seq_printf(m, ",rsize=%u", nfss->rsize);
460 	seq_printf(m, ",wsize=%u", nfss->wsize);
461 	if (nfss->bsize != 0)
462 		seq_printf(m, ",bsize=%u", nfss->bsize);
463 	seq_printf(m, ",namlen=%u", nfss->namelen);
464 	if (nfss->acregmin != NFS_DEF_ACREGMIN*HZ || showdefaults)
465 		seq_printf(m, ",acregmin=%u", nfss->acregmin/HZ);
466 	if (nfss->acregmax != NFS_DEF_ACREGMAX*HZ || showdefaults)
467 		seq_printf(m, ",acregmax=%u", nfss->acregmax/HZ);
468 	if (nfss->acdirmin != NFS_DEF_ACDIRMIN*HZ || showdefaults)
469 		seq_printf(m, ",acdirmin=%u", nfss->acdirmin/HZ);
470 	if (nfss->acdirmax != NFS_DEF_ACDIRMAX*HZ || showdefaults)
471 		seq_printf(m, ",acdirmax=%u", nfss->acdirmax/HZ);
472 	if (!(nfss->flags & (NFS_MOUNT_SOFT|NFS_MOUNT_SOFTERR)))
473 			seq_puts(m, ",hard");
474 	for (nfs_infop = nfs_info; nfs_infop->flag; nfs_infop++) {
475 		if (nfss->flags & nfs_infop->flag)
476 			seq_puts(m, nfs_infop->str);
477 		else
478 			seq_puts(m, nfs_infop->nostr);
479 	}
480 	rcu_read_lock();
481 	seq_printf(m, ",proto=%s",
482 		   rpc_peeraddr2str(nfss->client, RPC_DISPLAY_NETID));
483 	rcu_read_unlock();
484 	if (clp->cl_nconnect > 0)
485 		seq_printf(m, ",nconnect=%u", clp->cl_nconnect);
486 	if (version == 4) {
487 		if (clp->cl_max_connect > 1)
488 			seq_printf(m, ",max_connect=%u", clp->cl_max_connect);
489 		if (nfss->port != NFS_PORT)
490 			seq_printf(m, ",port=%u", nfss->port);
491 	} else
492 		if (nfss->port)
493 			seq_printf(m, ",port=%u", nfss->port);
494 
495 	seq_printf(m, ",timeo=%lu", 10U * nfss->client->cl_timeout->to_initval / HZ);
496 	seq_printf(m, ",retrans=%u", nfss->client->cl_timeout->to_retries);
497 	seq_printf(m, ",sec=%s", nfs_pseudoflavour_to_name(nfss->client->cl_auth->au_flavor));
498 	switch (clp->cl_xprtsec.policy) {
499 	case RPC_XPRTSEC_TLS_ANON:
500 		seq_puts(m, ",xprtsec=tls");
501 		break;
502 	case RPC_XPRTSEC_TLS_X509:
503 		seq_puts(m, ",xprtsec=mtls");
504 		break;
505 	default:
506 		break;
507 	}
508 
509 	if (version != 4)
510 		nfs_show_mountd_options(m, nfss, showdefaults);
511 	else
512 		nfs_show_nfsv4_options(m, nfss, showdefaults);
513 
514 	if (nfss->options & NFS_OPTION_FSCACHE)
515 		seq_puts(m, ",fsc");
516 
517 	if (nfss->options & NFS_OPTION_MIGRATION)
518 		seq_puts(m, ",migration");
519 
520 	if (nfss->flags & NFS_MOUNT_LOOKUP_CACHE_NONEG) {
521 		if (nfss->flags & NFS_MOUNT_LOOKUP_CACHE_NONE)
522 			seq_puts(m, ",lookupcache=none");
523 		else
524 			seq_puts(m, ",lookupcache=pos");
525 	}
526 
527 	local_flock = nfss->flags & NFS_MOUNT_LOCAL_FLOCK;
528 	local_fcntl = nfss->flags & NFS_MOUNT_LOCAL_FCNTL;
529 
530 	if (!local_flock && !local_fcntl)
531 		seq_puts(m, ",local_lock=none");
532 	else if (local_flock && local_fcntl)
533 		seq_puts(m, ",local_lock=all");
534 	else if (local_flock)
535 		seq_puts(m, ",local_lock=flock");
536 	else
537 		seq_puts(m, ",local_lock=posix");
538 
539 	if (nfss->flags & NFS_MOUNT_WRITE_EAGER) {
540 		if (nfss->flags & NFS_MOUNT_WRITE_WAIT)
541 			seq_puts(m, ",write=wait");
542 		else
543 			seq_puts(m, ",write=eager");
544 	}
545 }
546 
547 /*
548  * Describe the mount options on this VFS mountpoint
549  */
550 int nfs_show_options(struct seq_file *m, struct dentry *root)
551 {
552 	struct nfs_server *nfss = NFS_SB(root->d_sb);
553 
554 	nfs_show_mount_options(m, nfss, 0);
555 
556 	rcu_read_lock();
557 	seq_printf(m, ",addr=%s",
558 			rpc_peeraddr2str(nfss->nfs_client->cl_rpcclient,
559 							RPC_DISPLAY_ADDR));
560 	rcu_read_unlock();
561 
562 	return 0;
563 }
564 EXPORT_SYMBOL_GPL(nfs_show_options);
565 
566 #if IS_ENABLED(CONFIG_NFS_V4)
567 static void show_lease(struct seq_file *m, struct nfs_server *server)
568 {
569 	struct nfs_client *clp = server->nfs_client;
570 	unsigned long expire;
571 
572 	seq_printf(m, ",lease_time=%ld", clp->cl_lease_time / HZ);
573 	expire = clp->cl_last_renewal + clp->cl_lease_time;
574 	seq_printf(m, ",lease_expired=%ld",
575 		   time_after(expire, jiffies) ?  0 : (jiffies - expire) / HZ);
576 }
577 #ifdef CONFIG_NFS_V4_1
578 static void show_sessions(struct seq_file *m, struct nfs_server *server)
579 {
580 	if (nfs4_has_session(server->nfs_client))
581 		seq_puts(m, ",sessions");
582 }
583 #else
584 static void show_sessions(struct seq_file *m, struct nfs_server *server) {}
585 #endif
586 #endif
587 
588 #ifdef CONFIG_NFS_V4_1
589 static void show_pnfs(struct seq_file *m, struct nfs_server *server)
590 {
591 	seq_printf(m, ",pnfs=");
592 	if (server->pnfs_curr_ld)
593 		seq_printf(m, "%s", server->pnfs_curr_ld->name);
594 	else
595 		seq_printf(m, "not configured");
596 }
597 
598 static void show_implementation_id(struct seq_file *m, struct nfs_server *nfss)
599 {
600 	if (nfss->nfs_client && nfss->nfs_client->cl_implid) {
601 		struct nfs41_impl_id *impl_id = nfss->nfs_client->cl_implid;
602 		seq_printf(m, "\n\timpl_id:\tname='%s',domain='%s',"
603 			   "date='%llu,%u'",
604 			   impl_id->name, impl_id->domain,
605 			   impl_id->date.seconds, impl_id->date.nseconds);
606 	}
607 }
608 #else
609 #if IS_ENABLED(CONFIG_NFS_V4)
610 static void show_pnfs(struct seq_file *m, struct nfs_server *server)
611 {
612 }
613 #endif
614 static void show_implementation_id(struct seq_file *m, struct nfs_server *nfss)
615 {
616 }
617 #endif
618 
619 int nfs_show_devname(struct seq_file *m, struct dentry *root)
620 {
621 	char *page = (char *) __get_free_page(GFP_KERNEL);
622 	char *devname, *dummy;
623 	int err = 0;
624 	if (!page)
625 		return -ENOMEM;
626 	devname = nfs_path(&dummy, root, page, PAGE_SIZE, 0);
627 	if (IS_ERR(devname))
628 		err = PTR_ERR(devname);
629 	else
630 		seq_escape(m, devname, " \t\n\\");
631 	free_page((unsigned long)page);
632 	return err;
633 }
634 EXPORT_SYMBOL_GPL(nfs_show_devname);
635 
636 int nfs_show_path(struct seq_file *m, struct dentry *dentry)
637 {
638 	seq_puts(m, "/");
639 	return 0;
640 }
641 EXPORT_SYMBOL_GPL(nfs_show_path);
642 
643 /*
644  * Present statistical information for this VFS mountpoint
645  */
646 int nfs_show_stats(struct seq_file *m, struct dentry *root)
647 {
648 	int i, cpu;
649 	struct nfs_server *nfss = NFS_SB(root->d_sb);
650 	struct rpc_auth *auth = nfss->client->cl_auth;
651 	struct nfs_iostats totals = { };
652 
653 	seq_printf(m, "statvers=%s", NFS_IOSTAT_VERS);
654 
655 	/*
656 	 * Display all mount option settings
657 	 */
658 	seq_puts(m, "\n\topts:\t");
659 	seq_puts(m, sb_rdonly(root->d_sb) ? "ro" : "rw");
660 	seq_puts(m, root->d_sb->s_flags & SB_SYNCHRONOUS ? ",sync" : "");
661 	seq_puts(m, root->d_sb->s_flags & SB_NOATIME ? ",noatime" : "");
662 	seq_puts(m, root->d_sb->s_flags & SB_NODIRATIME ? ",nodiratime" : "");
663 	nfs_show_mount_options(m, nfss, 1);
664 
665 	seq_printf(m, "\n\tage:\t%lu", (jiffies - nfss->mount_time) / HZ);
666 
667 	show_implementation_id(m, nfss);
668 
669 	seq_puts(m, "\n\tcaps:\t");
670 	seq_printf(m, "caps=0x%x", nfss->caps);
671 	seq_printf(m, ",wtmult=%u", nfss->wtmult);
672 	seq_printf(m, ",dtsize=%u", nfss->dtsize);
673 	seq_printf(m, ",bsize=%u", nfss->bsize);
674 	seq_printf(m, ",namlen=%u", nfss->namelen);
675 
676 #if IS_ENABLED(CONFIG_NFS_V4)
677 	if (nfss->nfs_client->rpc_ops->version == 4) {
678 		seq_puts(m, "\n\tnfsv4:\t");
679 		seq_printf(m, "bm0=0x%x", nfss->attr_bitmask[0]);
680 		seq_printf(m, ",bm1=0x%x", nfss->attr_bitmask[1]);
681 		seq_printf(m, ",bm2=0x%x", nfss->attr_bitmask[2]);
682 		seq_printf(m, ",acl=0x%x", nfss->acl_bitmask);
683 		show_sessions(m, nfss);
684 		show_pnfs(m, nfss);
685 		show_lease(m, nfss);
686 	}
687 #endif
688 
689 	/*
690 	 * Display security flavor in effect for this mount
691 	 */
692 	seq_printf(m, "\n\tsec:\tflavor=%u", auth->au_ops->au_flavor);
693 	if (auth->au_flavor)
694 		seq_printf(m, ",pseudoflavor=%u", auth->au_flavor);
695 
696 	/*
697 	 * Display superblock I/O counters
698 	 */
699 	for_each_possible_cpu(cpu) {
700 		struct nfs_iostats *stats;
701 
702 		preempt_disable();
703 		stats = per_cpu_ptr(nfss->io_stats, cpu);
704 
705 		for (i = 0; i < __NFSIOS_COUNTSMAX; i++)
706 			totals.events[i] += stats->events[i];
707 		for (i = 0; i < __NFSIOS_BYTESMAX; i++)
708 			totals.bytes[i] += stats->bytes[i];
709 
710 		preempt_enable();
711 	}
712 
713 	seq_puts(m, "\n\tevents:\t");
714 	for (i = 0; i < __NFSIOS_COUNTSMAX; i++)
715 		seq_printf(m, "%lu ", totals.events[i]);
716 	seq_puts(m, "\n\tbytes:\t");
717 	for (i = 0; i < __NFSIOS_BYTESMAX; i++)
718 		seq_printf(m, "%Lu ", totals.bytes[i]);
719 	seq_putc(m, '\n');
720 
721 	rpc_clnt_show_stats(m, nfss->client);
722 
723 	return 0;
724 }
725 EXPORT_SYMBOL_GPL(nfs_show_stats);
726 
727 /*
728  * Begin unmount by attempting to remove all automounted mountpoints we added
729  * in response to xdev traversals and referrals
730  */
731 void nfs_umount_begin(struct super_block *sb)
732 {
733 	struct nfs_server *server;
734 	struct rpc_clnt *rpc;
735 
736 	server = NFS_SB(sb);
737 	/* -EIO all pending I/O */
738 	rpc = server->client_acl;
739 	if (!IS_ERR(rpc))
740 		rpc_killall_tasks(rpc);
741 	rpc = server->client;
742 	if (!IS_ERR(rpc))
743 		rpc_killall_tasks(rpc);
744 }
745 EXPORT_SYMBOL_GPL(nfs_umount_begin);
746 
747 /*
748  * Return true if 'match' is in auth_info or auth_info is empty.
749  * Return false otherwise.
750  */
751 bool nfs_auth_info_match(const struct nfs_auth_info *auth_info,
752 			 rpc_authflavor_t match)
753 {
754 	int i;
755 
756 	if (!auth_info->flavor_len)
757 		return true;
758 
759 	for (i = 0; i < auth_info->flavor_len; i++) {
760 		if (auth_info->flavors[i] == match)
761 			return true;
762 	}
763 	return false;
764 }
765 EXPORT_SYMBOL_GPL(nfs_auth_info_match);
766 
767 /*
768  * Ensure that a specified authtype in ctx->auth_info is supported by
769  * the server. Returns 0 and sets ctx->selected_flavor if it's ok, and
770  * -EACCES if not.
771  */
772 static int nfs_verify_authflavors(struct nfs_fs_context *ctx,
773 				  rpc_authflavor_t *server_authlist,
774 				  unsigned int count)
775 {
776 	rpc_authflavor_t flavor = RPC_AUTH_MAXFLAVOR;
777 	bool found_auth_null = false;
778 	unsigned int i;
779 
780 	/*
781 	 * If the sec= mount option is used, the specified flavor or AUTH_NULL
782 	 * must be in the list returned by the server.
783 	 *
784 	 * AUTH_NULL has a special meaning when it's in the server list - it
785 	 * means that the server will ignore the rpc creds, so any flavor
786 	 * can be used but still use the sec= that was specified.
787 	 *
788 	 * Note also that the MNT procedure in MNTv1 does not return a list
789 	 * of supported security flavors. In this case, nfs_mount() fabricates
790 	 * a security flavor list containing just AUTH_NULL.
791 	 */
792 	for (i = 0; i < count; i++) {
793 		flavor = server_authlist[i];
794 
795 		if (nfs_auth_info_match(&ctx->auth_info, flavor))
796 			goto out;
797 
798 		if (flavor == RPC_AUTH_NULL)
799 			found_auth_null = true;
800 	}
801 
802 	if (found_auth_null) {
803 		flavor = ctx->auth_info.flavors[0];
804 		goto out;
805 	}
806 
807 	dfprintk(MOUNT,
808 		 "NFS: specified auth flavors not supported by server\n");
809 	return -EACCES;
810 
811 out:
812 	ctx->selected_flavor = flavor;
813 	dfprintk(MOUNT, "NFS: using auth flavor %u\n", ctx->selected_flavor);
814 	return 0;
815 }
816 
817 /*
818  * Use the remote server's MOUNT service to request the NFS file handle
819  * corresponding to the provided path.
820  */
821 static int nfs_request_mount(struct fs_context *fc,
822 			     struct nfs_fh *root_fh,
823 			     rpc_authflavor_t *server_authlist,
824 			     unsigned int *server_authlist_len)
825 {
826 	struct nfs_fs_context *ctx = nfs_fc2context(fc);
827 	struct nfs_mount_request request = {
828 		.sap		= &ctx->mount_server._address,
829 		.dirpath	= ctx->nfs_server.export_path,
830 		.protocol	= ctx->mount_server.protocol,
831 		.fh		= root_fh,
832 		.noresvport	= ctx->flags & NFS_MOUNT_NORESVPORT,
833 		.auth_flav_len	= server_authlist_len,
834 		.auth_flavs	= server_authlist,
835 		.net		= fc->net_ns,
836 	};
837 	int status;
838 
839 	if (ctx->mount_server.version == 0) {
840 		switch (ctx->version) {
841 			default:
842 				ctx->mount_server.version = NFS_MNT3_VERSION;
843 				break;
844 			case 2:
845 				ctx->mount_server.version = NFS_MNT_VERSION;
846 		}
847 	}
848 	request.version = ctx->mount_server.version;
849 
850 	if (ctx->mount_server.hostname)
851 		request.hostname = ctx->mount_server.hostname;
852 	else
853 		request.hostname = ctx->nfs_server.hostname;
854 
855 	/*
856 	 * Construct the mount server's address.
857 	 */
858 	if (ctx->mount_server.address.sa_family == AF_UNSPEC) {
859 		memcpy(request.sap, &ctx->nfs_server._address,
860 		       ctx->nfs_server.addrlen);
861 		ctx->mount_server.addrlen = ctx->nfs_server.addrlen;
862 	}
863 	request.salen = ctx->mount_server.addrlen;
864 	nfs_set_port(request.sap, &ctx->mount_server.port, 0);
865 
866 	/*
867 	 * Now ask the mount server to map our export path
868 	 * to a file handle.
869 	 */
870 	status = nfs_mount(&request, ctx->timeo, ctx->retrans);
871 	if (status != 0) {
872 		dfprintk(MOUNT, "NFS: unable to mount server %s, error %d\n",
873 				request.hostname, status);
874 		return status;
875 	}
876 
877 	return 0;
878 }
879 
880 static struct nfs_server *nfs_try_mount_request(struct fs_context *fc)
881 {
882 	struct nfs_fs_context *ctx = nfs_fc2context(fc);
883 	int status;
884 	unsigned int i;
885 	bool tried_auth_unix = false;
886 	bool auth_null_in_list = false;
887 	struct nfs_server *server = ERR_PTR(-EACCES);
888 	rpc_authflavor_t authlist[NFS_MAX_SECFLAVORS];
889 	unsigned int authlist_len = ARRAY_SIZE(authlist);
890 
891 	status = nfs_request_mount(fc, ctx->mntfh, authlist, &authlist_len);
892 	if (status)
893 		return ERR_PTR(status);
894 
895 	/*
896 	 * Was a sec= authflavor specified in the options? First, verify
897 	 * whether the server supports it, and then just try to use it if so.
898 	 */
899 	if (ctx->auth_info.flavor_len > 0) {
900 		status = nfs_verify_authflavors(ctx, authlist, authlist_len);
901 		dfprintk(MOUNT, "NFS: using auth flavor %u\n",
902 			 ctx->selected_flavor);
903 		if (status)
904 			return ERR_PTR(status);
905 		return ctx->nfs_mod->rpc_ops->create_server(fc);
906 	}
907 
908 	/*
909 	 * No sec= option was provided. RFC 2623, section 2.7 suggests we
910 	 * SHOULD prefer the flavor listed first. However, some servers list
911 	 * AUTH_NULL first. Avoid ever choosing AUTH_NULL.
912 	 */
913 	for (i = 0; i < authlist_len; ++i) {
914 		rpc_authflavor_t flavor;
915 		struct rpcsec_gss_info info;
916 
917 		flavor = authlist[i];
918 		switch (flavor) {
919 		case RPC_AUTH_UNIX:
920 			tried_auth_unix = true;
921 			break;
922 		case RPC_AUTH_NULL:
923 			auth_null_in_list = true;
924 			continue;
925 		default:
926 			if (rpcauth_get_gssinfo(flavor, &info) != 0)
927 				continue;
928 			break;
929 		}
930 		dfprintk(MOUNT, "NFS: attempting to use auth flavor %u\n", flavor);
931 		ctx->selected_flavor = flavor;
932 		server = ctx->nfs_mod->rpc_ops->create_server(fc);
933 		if (!IS_ERR(server))
934 			return server;
935 	}
936 
937 	/*
938 	 * Nothing we tried so far worked. At this point, give up if we've
939 	 * already tried AUTH_UNIX or if the server's list doesn't contain
940 	 * AUTH_NULL
941 	 */
942 	if (tried_auth_unix || !auth_null_in_list)
943 		return server;
944 
945 	/* Last chance! Try AUTH_UNIX */
946 	dfprintk(MOUNT, "NFS: attempting to use auth flavor %u\n", RPC_AUTH_UNIX);
947 	ctx->selected_flavor = RPC_AUTH_UNIX;
948 	return ctx->nfs_mod->rpc_ops->create_server(fc);
949 }
950 
951 int nfs_try_get_tree(struct fs_context *fc)
952 {
953 	struct nfs_fs_context *ctx = nfs_fc2context(fc);
954 
955 	if (ctx->need_mount)
956 		ctx->server = nfs_try_mount_request(fc);
957 	else
958 		ctx->server = ctx->nfs_mod->rpc_ops->create_server(fc);
959 
960 	return nfs_get_tree_common(fc);
961 }
962 EXPORT_SYMBOL_GPL(nfs_try_get_tree);
963 
964 
965 #define NFS_REMOUNT_CMP_FLAGMASK ~(NFS_MOUNT_INTR \
966 		| NFS_MOUNT_SECURE \
967 		| NFS_MOUNT_TCP \
968 		| NFS_MOUNT_VER3 \
969 		| NFS_MOUNT_KERBEROS \
970 		| NFS_MOUNT_NONLM \
971 		| NFS_MOUNT_BROKEN_SUID \
972 		| NFS_MOUNT_STRICTLOCK \
973 		| NFS_MOUNT_LEGACY_INTERFACE)
974 
975 #define NFS_MOUNT_CMP_FLAGMASK (NFS_REMOUNT_CMP_FLAGMASK & \
976 		~(NFS_MOUNT_UNSHARED | NFS_MOUNT_NORESVPORT))
977 
978 static int
979 nfs_compare_remount_data(struct nfs_server *nfss,
980 			 struct nfs_fs_context *ctx)
981 {
982 	if ((ctx->flags ^ nfss->flags) & NFS_REMOUNT_CMP_FLAGMASK ||
983 	    ctx->rsize != nfss->rsize ||
984 	    ctx->wsize != nfss->wsize ||
985 	    ctx->version != nfss->nfs_client->rpc_ops->version ||
986 	    ctx->minorversion != nfss->nfs_client->cl_minorversion ||
987 	    ctx->retrans != nfss->client->cl_timeout->to_retries ||
988 	    !nfs_auth_info_match(&ctx->auth_info, nfss->client->cl_auth->au_flavor) ||
989 	    ctx->acregmin != nfss->acregmin / HZ ||
990 	    ctx->acregmax != nfss->acregmax / HZ ||
991 	    ctx->acdirmin != nfss->acdirmin / HZ ||
992 	    ctx->acdirmax != nfss->acdirmax / HZ ||
993 	    ctx->timeo != (10U * nfss->client->cl_timeout->to_initval / HZ) ||
994 	    (ctx->options & NFS_OPTION_FSCACHE) != (nfss->options & NFS_OPTION_FSCACHE) ||
995 	    ctx->nfs_server.port != nfss->port ||
996 	    ctx->nfs_server.addrlen != nfss->nfs_client->cl_addrlen ||
997 	    !rpc_cmp_addr((struct sockaddr *)&ctx->nfs_server.address,
998 			  (struct sockaddr *)&nfss->nfs_client->cl_addr))
999 		return -EINVAL;
1000 
1001 	return 0;
1002 }
1003 
1004 int nfs_reconfigure(struct fs_context *fc)
1005 {
1006 	struct nfs_fs_context *ctx = nfs_fc2context(fc);
1007 	struct super_block *sb = fc->root->d_sb;
1008 	struct nfs_server *nfss = sb->s_fs_info;
1009 	int ret;
1010 
1011 	sync_filesystem(sb);
1012 
1013 	/*
1014 	 * Userspace mount programs that send binary options generally send
1015 	 * them populated with default values. We have no way to know which
1016 	 * ones were explicitly specified. Fall back to legacy behavior and
1017 	 * just return success.
1018 	 */
1019 	if (ctx->skip_reconfig_option_check)
1020 		return 0;
1021 
1022 	/*
1023 	 * noac is a special case. It implies -o sync, but that's not
1024 	 * necessarily reflected in the mtab options. reconfigure_super
1025 	 * will clear SB_SYNCHRONOUS if -o sync wasn't specified in the
1026 	 * remount options, so we have to explicitly reset it.
1027 	 */
1028 	if (ctx->flags & NFS_MOUNT_NOAC) {
1029 		fc->sb_flags |= SB_SYNCHRONOUS;
1030 		fc->sb_flags_mask |= SB_SYNCHRONOUS;
1031 	}
1032 
1033 	/* compare new mount options with old ones */
1034 	ret = nfs_compare_remount_data(nfss, ctx);
1035 	if (ret)
1036 		return ret;
1037 
1038 	return nfs_probe_server(nfss, NFS_FH(d_inode(fc->root)));
1039 }
1040 EXPORT_SYMBOL_GPL(nfs_reconfigure);
1041 
1042 /*
1043  * Finish setting up an NFS superblock
1044  */
1045 static void nfs_fill_super(struct super_block *sb, struct nfs_fs_context *ctx)
1046 {
1047 	struct nfs_server *server = NFS_SB(sb);
1048 
1049 	sb->s_blocksize_bits = 0;
1050 	sb->s_blocksize = 0;
1051 	sb->s_xattr = server->nfs_client->cl_nfs_mod->xattr;
1052 	sb->s_op = server->nfs_client->cl_nfs_mod->sops;
1053 	if (ctx->bsize)
1054 		sb->s_blocksize = nfs_block_size(ctx->bsize, &sb->s_blocksize_bits);
1055 
1056 	switch (server->nfs_client->rpc_ops->version) {
1057 	case 2:
1058 		sb->s_time_gran = 1000;
1059 		sb->s_time_min = 0;
1060 		sb->s_time_max = U32_MAX;
1061 		break;
1062 	case 3:
1063 		/*
1064 		 * The VFS shouldn't apply the umask to mode bits.
1065 		 * We will do so ourselves when necessary.
1066 		 */
1067 		sb->s_flags |= SB_POSIXACL;
1068 		sb->s_time_gran = 1;
1069 		sb->s_time_min = 0;
1070 		sb->s_time_max = U32_MAX;
1071 		sb->s_export_op = &nfs_export_ops;
1072 		break;
1073 	case 4:
1074 		sb->s_flags |= SB_POSIXACL;
1075 		sb->s_time_gran = 1;
1076 		sb->s_time_min = S64_MIN;
1077 		sb->s_time_max = S64_MAX;
1078 		if (server->caps & NFS_CAP_ATOMIC_OPEN_V1)
1079 			sb->s_export_op = &nfs_export_ops;
1080 		break;
1081 	}
1082 
1083 	sb->s_magic = NFS_SUPER_MAGIC;
1084 
1085 	/* We probably want something more informative here */
1086 	snprintf(sb->s_id, sizeof(sb->s_id),
1087 		 "%u:%u", MAJOR(sb->s_dev), MINOR(sb->s_dev));
1088 
1089 	if (sb->s_blocksize == 0)
1090 		sb->s_blocksize = nfs_block_bits(server->wsize,
1091 						 &sb->s_blocksize_bits);
1092 
1093 	nfs_super_set_maxbytes(sb, server->maxfilesize);
1094 	nfs_sysfs_move_server_to_sb(sb);
1095 	server->has_sec_mnt_opts = ctx->has_sec_mnt_opts;
1096 }
1097 
1098 static int nfs_compare_mount_options(const struct super_block *s, const struct nfs_server *b,
1099 				     const struct fs_context *fc)
1100 {
1101 	const struct nfs_server *a = s->s_fs_info;
1102 	const struct rpc_clnt *clnt_a = a->client;
1103 	const struct rpc_clnt *clnt_b = b->client;
1104 
1105 	if ((s->s_flags & NFS_SB_MASK) != (fc->sb_flags & NFS_SB_MASK))
1106 		goto Ebusy;
1107 	if (a->nfs_client != b->nfs_client)
1108 		goto Ebusy;
1109 	if ((a->flags ^ b->flags) & NFS_MOUNT_CMP_FLAGMASK)
1110 		goto Ebusy;
1111 	if (a->wsize != b->wsize)
1112 		goto Ebusy;
1113 	if (a->rsize != b->rsize)
1114 		goto Ebusy;
1115 	if (a->acregmin != b->acregmin)
1116 		goto Ebusy;
1117 	if (a->acregmax != b->acregmax)
1118 		goto Ebusy;
1119 	if (a->acdirmin != b->acdirmin)
1120 		goto Ebusy;
1121 	if (a->acdirmax != b->acdirmax)
1122 		goto Ebusy;
1123 	if (clnt_a->cl_auth->au_flavor != clnt_b->cl_auth->au_flavor)
1124 		goto Ebusy;
1125 	return 1;
1126 Ebusy:
1127 	return 0;
1128 }
1129 
1130 static int nfs_set_super(struct super_block *s, struct fs_context *fc)
1131 {
1132 	struct nfs_server *server = fc->s_fs_info;
1133 	int ret;
1134 
1135 	s->s_d_op = server->nfs_client->rpc_ops->dentry_ops;
1136 	ret = set_anon_super(s, server);
1137 	if (ret == 0)
1138 		server->s_dev = s->s_dev;
1139 	return ret;
1140 }
1141 
1142 static int nfs_compare_super_address(struct nfs_server *server1,
1143 				     struct nfs_server *server2)
1144 {
1145 	struct sockaddr *sap1, *sap2;
1146 	struct rpc_xprt *xprt1 = server1->client->cl_xprt;
1147 	struct rpc_xprt *xprt2 = server2->client->cl_xprt;
1148 
1149 	if (!net_eq(xprt1->xprt_net, xprt2->xprt_net))
1150 		return 0;
1151 
1152 	sap1 = (struct sockaddr *)&server1->nfs_client->cl_addr;
1153 	sap2 = (struct sockaddr *)&server2->nfs_client->cl_addr;
1154 
1155 	if (sap1->sa_family != sap2->sa_family)
1156 		return 0;
1157 
1158 	switch (sap1->sa_family) {
1159 	case AF_INET: {
1160 		struct sockaddr_in *sin1 = (struct sockaddr_in *)sap1;
1161 		struct sockaddr_in *sin2 = (struct sockaddr_in *)sap2;
1162 		if (sin1->sin_addr.s_addr != sin2->sin_addr.s_addr)
1163 			return 0;
1164 		if (sin1->sin_port != sin2->sin_port)
1165 			return 0;
1166 		break;
1167 	}
1168 	case AF_INET6: {
1169 		struct sockaddr_in6 *sin1 = (struct sockaddr_in6 *)sap1;
1170 		struct sockaddr_in6 *sin2 = (struct sockaddr_in6 *)sap2;
1171 		if (!ipv6_addr_equal(&sin1->sin6_addr, &sin2->sin6_addr))
1172 			return 0;
1173 		if (sin1->sin6_port != sin2->sin6_port)
1174 			return 0;
1175 		break;
1176 	}
1177 	default:
1178 		return 0;
1179 	}
1180 
1181 	return 1;
1182 }
1183 
1184 static int nfs_compare_userns(const struct nfs_server *old,
1185 		const struct nfs_server *new)
1186 {
1187 	const struct user_namespace *oldns = &init_user_ns;
1188 	const struct user_namespace *newns = &init_user_ns;
1189 
1190 	if (old->client && old->client->cl_cred)
1191 		oldns = old->client->cl_cred->user_ns;
1192 	if (new->client && new->client->cl_cred)
1193 		newns = new->client->cl_cred->user_ns;
1194 	if (oldns != newns)
1195 		return 0;
1196 	return 1;
1197 }
1198 
1199 static int nfs_compare_super(struct super_block *sb, struct fs_context *fc)
1200 {
1201 	struct nfs_server *server = fc->s_fs_info, *old = NFS_SB(sb);
1202 
1203 	if (!nfs_compare_super_address(old, server))
1204 		return 0;
1205 	/* Note: NFS_MOUNT_UNSHARED == NFS4_MOUNT_UNSHARED */
1206 	if (old->flags & NFS_MOUNT_UNSHARED)
1207 		return 0;
1208 	if (memcmp(&old->fsid, &server->fsid, sizeof(old->fsid)) != 0)
1209 		return 0;
1210 	if (!nfs_compare_userns(old, server))
1211 		return 0;
1212 	if ((old->has_sec_mnt_opts || fc->security) &&
1213 			security_sb_mnt_opts_compat(sb, fc->security))
1214 		return 0;
1215 	return nfs_compare_mount_options(sb, server, fc);
1216 }
1217 
1218 #ifdef CONFIG_NFS_FSCACHE
1219 static int nfs_get_cache_cookie(struct super_block *sb,
1220 				struct nfs_fs_context *ctx)
1221 {
1222 	struct nfs_server *nfss = NFS_SB(sb);
1223 	char *uniq = NULL;
1224 	int ulen = 0;
1225 
1226 	nfss->fscache = NULL;
1227 
1228 	if (!ctx)
1229 		return 0;
1230 
1231 	if (ctx->clone_data.sb) {
1232 		struct nfs_server *mnt_s = NFS_SB(ctx->clone_data.sb);
1233 		if (!(mnt_s->options & NFS_OPTION_FSCACHE))
1234 			return 0;
1235 		if (mnt_s->fscache_uniq) {
1236 			uniq = mnt_s->fscache_uniq;
1237 			ulen = strlen(uniq);
1238 		}
1239 	} else {
1240 		if (!(ctx->options & NFS_OPTION_FSCACHE))
1241 			return 0;
1242 		if (ctx->fscache_uniq) {
1243 			uniq = ctx->fscache_uniq;
1244 			ulen = strlen(ctx->fscache_uniq);
1245 		}
1246 	}
1247 
1248 	return nfs_fscache_get_super_cookie(sb, uniq, ulen);
1249 }
1250 #else
1251 static int nfs_get_cache_cookie(struct super_block *sb,
1252 				struct nfs_fs_context *ctx)
1253 {
1254 	return 0;
1255 }
1256 #endif
1257 
1258 int nfs_get_tree_common(struct fs_context *fc)
1259 {
1260 	struct nfs_fs_context *ctx = nfs_fc2context(fc);
1261 	struct super_block *s;
1262 	int (*compare_super)(struct super_block *, struct fs_context *) = nfs_compare_super;
1263 	struct nfs_server *server = ctx->server;
1264 	int error;
1265 
1266 	ctx->server = NULL;
1267 	if (IS_ERR(server))
1268 		return PTR_ERR(server);
1269 
1270 	if (server->flags & NFS_MOUNT_UNSHARED)
1271 		compare_super = NULL;
1272 
1273 	/* -o noac implies -o sync */
1274 	if (server->flags & NFS_MOUNT_NOAC)
1275 		fc->sb_flags |= SB_SYNCHRONOUS;
1276 
1277 	if (ctx->clone_data.sb)
1278 		if (ctx->clone_data.sb->s_flags & SB_SYNCHRONOUS)
1279 			fc->sb_flags |= SB_SYNCHRONOUS;
1280 
1281 	/* Get a superblock - note that we may end up sharing one that already exists */
1282 	fc->s_fs_info = server;
1283 	s = sget_fc(fc, compare_super, nfs_set_super);
1284 	fc->s_fs_info = NULL;
1285 	if (IS_ERR(s)) {
1286 		error = PTR_ERR(s);
1287 		nfs_errorf(fc, "NFS: Couldn't get superblock");
1288 		goto out_err_nosb;
1289 	}
1290 
1291 	if (s->s_fs_info != server) {
1292 		nfs_free_server(server);
1293 		server = NULL;
1294 	} else {
1295 		error = super_setup_bdi_name(s, "%u:%u", MAJOR(server->s_dev),
1296 					     MINOR(server->s_dev));
1297 		if (error)
1298 			goto error_splat_super;
1299 		s->s_bdi->io_pages = server->rpages;
1300 		server->super = s;
1301 	}
1302 
1303 	if (!s->s_root) {
1304 		unsigned bsize = ctx->clone_data.inherited_bsize;
1305 		/* initial superblock/root creation */
1306 		nfs_fill_super(s, ctx);
1307 		if (bsize) {
1308 			s->s_blocksize_bits = bsize;
1309 			s->s_blocksize = 1U << bsize;
1310 		}
1311 		error = nfs_get_cache_cookie(s, ctx);
1312 		if (error < 0)
1313 			goto error_splat_super;
1314 	}
1315 
1316 	error = nfs_get_root(s, fc);
1317 	if (error < 0) {
1318 		nfs_errorf(fc, "NFS: Couldn't get root dentry");
1319 		goto error_splat_super;
1320 	}
1321 
1322 	s->s_flags |= SB_ACTIVE;
1323 	error = 0;
1324 
1325 out:
1326 	return error;
1327 
1328 out_err_nosb:
1329 	nfs_free_server(server);
1330 	goto out;
1331 error_splat_super:
1332 	deactivate_locked_super(s);
1333 	goto out;
1334 }
1335 
1336 /*
1337  * Destroy an NFS superblock
1338  */
1339 void nfs_kill_super(struct super_block *s)
1340 {
1341 	struct nfs_server *server = NFS_SB(s);
1342 
1343 	nfs_sysfs_move_sb_to_server(server);
1344 	kill_anon_super(s);
1345 
1346 	nfs_fscache_release_super_cookie(s);
1347 
1348 	nfs_free_server(server);
1349 }
1350 EXPORT_SYMBOL_GPL(nfs_kill_super);
1351 
1352 #if IS_ENABLED(CONFIG_NFS_V4)
1353 
1354 /*
1355  * NFS v4 module parameters need to stay in the
1356  * NFS client for backwards compatibility
1357  */
1358 unsigned int nfs_callback_set_tcpport;
1359 unsigned short nfs_callback_nr_threads;
1360 /* Default cache timeout is 10 minutes */
1361 unsigned int nfs_idmap_cache_timeout = 600;
1362 /* Turn off NFSv4 uid/gid mapping when using AUTH_SYS */
1363 bool nfs4_disable_idmapping = true;
1364 unsigned short max_session_slots = NFS4_DEF_SLOT_TABLE_SIZE;
1365 unsigned short max_session_cb_slots = NFS4_DEF_CB_SLOT_TABLE_SIZE;
1366 unsigned short send_implementation_id = 1;
1367 char nfs4_client_id_uniquifier[NFS4_CLIENT_ID_UNIQ_LEN] = "";
1368 bool recover_lost_locks = false;
1369 
1370 EXPORT_SYMBOL_GPL(nfs_callback_nr_threads);
1371 EXPORT_SYMBOL_GPL(nfs_callback_set_tcpport);
1372 EXPORT_SYMBOL_GPL(nfs_idmap_cache_timeout);
1373 EXPORT_SYMBOL_GPL(nfs4_disable_idmapping);
1374 EXPORT_SYMBOL_GPL(max_session_slots);
1375 EXPORT_SYMBOL_GPL(max_session_cb_slots);
1376 EXPORT_SYMBOL_GPL(send_implementation_id);
1377 EXPORT_SYMBOL_GPL(nfs4_client_id_uniquifier);
1378 EXPORT_SYMBOL_GPL(recover_lost_locks);
1379 
1380 #define NFS_CALLBACK_MAXPORTNR (65535U)
1381 
1382 static int param_set_portnr(const char *val, const struct kernel_param *kp)
1383 {
1384 	unsigned long num;
1385 	int ret;
1386 
1387 	if (!val)
1388 		return -EINVAL;
1389 	ret = kstrtoul(val, 0, &num);
1390 	if (ret || num > NFS_CALLBACK_MAXPORTNR)
1391 		return -EINVAL;
1392 	*((unsigned int *)kp->arg) = num;
1393 	return 0;
1394 }
1395 static const struct kernel_param_ops param_ops_portnr = {
1396 	.set = param_set_portnr,
1397 	.get = param_get_uint,
1398 };
1399 #define param_check_portnr(name, p) __param_check(name, p, unsigned int)
1400 
1401 module_param_named(callback_tcpport, nfs_callback_set_tcpport, portnr, 0644);
1402 module_param_named(callback_nr_threads, nfs_callback_nr_threads, ushort, 0644);
1403 MODULE_PARM_DESC(callback_nr_threads, "Number of threads that will be "
1404 		"assigned to the NFSv4 callback channels.");
1405 module_param(nfs_idmap_cache_timeout, int, 0644);
1406 module_param(nfs4_disable_idmapping, bool, 0644);
1407 module_param_string(nfs4_unique_id, nfs4_client_id_uniquifier,
1408 			NFS4_CLIENT_ID_UNIQ_LEN, 0600);
1409 MODULE_PARM_DESC(nfs4_disable_idmapping,
1410 		"Turn off NFSv4 idmapping when using 'sec=sys'");
1411 module_param(max_session_slots, ushort, 0644);
1412 MODULE_PARM_DESC(max_session_slots, "Maximum number of outstanding NFSv4.1 "
1413 		"requests the client will negotiate");
1414 module_param(max_session_cb_slots, ushort, 0644);
1415 MODULE_PARM_DESC(max_session_cb_slots, "Maximum number of parallel NFSv4.1 "
1416 		"callbacks the client will process for a given server");
1417 module_param(send_implementation_id, ushort, 0644);
1418 MODULE_PARM_DESC(send_implementation_id,
1419 		"Send implementation ID with NFSv4.1 exchange_id");
1420 MODULE_PARM_DESC(nfs4_unique_id, "nfs_client_id4 uniquifier string");
1421 
1422 module_param(recover_lost_locks, bool, 0644);
1423 MODULE_PARM_DESC(recover_lost_locks,
1424 		 "If the server reports that a lock might be lost, "
1425 		 "try to recover it risking data corruption.");
1426 
1427 
1428 #endif /* CONFIG_NFS_V4 */
1429