xref: /linux/fs/nfs/super.c (revision 24ce659dcc02c21f8d6c0a7589c3320a4dfa8152)
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 
61 #include "nfs4_fs.h"
62 #include "callback.h"
63 #include "delegation.h"
64 #include "iostat.h"
65 #include "internal.h"
66 #include "fscache.h"
67 #include "nfs4session.h"
68 #include "pnfs.h"
69 #include "nfs.h"
70 
71 #define NFSDBG_FACILITY		NFSDBG_VFS
72 
73 const struct super_operations nfs_sops = {
74 	.alloc_inode	= nfs_alloc_inode,
75 	.free_inode	= nfs_free_inode,
76 	.write_inode	= nfs_write_inode,
77 	.drop_inode	= nfs_drop_inode,
78 	.statfs		= nfs_statfs,
79 	.evict_inode	= nfs_evict_inode,
80 	.umount_begin	= nfs_umount_begin,
81 	.show_options	= nfs_show_options,
82 	.show_devname	= nfs_show_devname,
83 	.show_path	= nfs_show_path,
84 	.show_stats	= nfs_show_stats,
85 };
86 EXPORT_SYMBOL_GPL(nfs_sops);
87 
88 #if IS_ENABLED(CONFIG_NFS_V4)
89 static int __init register_nfs4_fs(void)
90 {
91 	return register_filesystem(&nfs4_fs_type);
92 }
93 
94 static void unregister_nfs4_fs(void)
95 {
96 	unregister_filesystem(&nfs4_fs_type);
97 }
98 #else
99 static int __init register_nfs4_fs(void)
100 {
101 	return 0;
102 }
103 
104 static void unregister_nfs4_fs(void)
105 {
106 }
107 #endif
108 
109 static struct shrinker acl_shrinker = {
110 	.count_objects	= nfs_access_cache_count,
111 	.scan_objects	= nfs_access_cache_scan,
112 	.seeks		= DEFAULT_SEEKS,
113 };
114 
115 /*
116  * Register the NFS filesystems
117  */
118 int __init register_nfs_fs(void)
119 {
120 	int ret;
121 
122         ret = register_filesystem(&nfs_fs_type);
123 	if (ret < 0)
124 		goto error_0;
125 
126 	ret = register_nfs4_fs();
127 	if (ret < 0)
128 		goto error_1;
129 
130 	ret = nfs_register_sysctl();
131 	if (ret < 0)
132 		goto error_2;
133 	ret = register_shrinker(&acl_shrinker);
134 	if (ret < 0)
135 		goto error_3;
136 	return 0;
137 error_3:
138 	nfs_unregister_sysctl();
139 error_2:
140 	unregister_nfs4_fs();
141 error_1:
142 	unregister_filesystem(&nfs_fs_type);
143 error_0:
144 	return ret;
145 }
146 
147 /*
148  * Unregister the NFS filesystems
149  */
150 void __exit unregister_nfs_fs(void)
151 {
152 	unregister_shrinker(&acl_shrinker);
153 	nfs_unregister_sysctl();
154 	unregister_nfs4_fs();
155 	unregister_filesystem(&nfs_fs_type);
156 }
157 
158 bool nfs_sb_active(struct super_block *sb)
159 {
160 	struct nfs_server *server = NFS_SB(sb);
161 
162 	if (!atomic_inc_not_zero(&sb->s_active))
163 		return false;
164 	if (atomic_inc_return(&server->active) != 1)
165 		atomic_dec(&sb->s_active);
166 	return true;
167 }
168 EXPORT_SYMBOL_GPL(nfs_sb_active);
169 
170 void nfs_sb_deactive(struct super_block *sb)
171 {
172 	struct nfs_server *server = NFS_SB(sb);
173 
174 	if (atomic_dec_and_test(&server->active))
175 		deactivate_super(sb);
176 }
177 EXPORT_SYMBOL_GPL(nfs_sb_deactive);
178 
179 static int __nfs_list_for_each_server(struct list_head *head,
180 		int (*fn)(struct nfs_server *, void *),
181 		void *data)
182 {
183 	struct nfs_server *server, *last = NULL;
184 	int ret = 0;
185 
186 	rcu_read_lock();
187 	list_for_each_entry_rcu(server, head, client_link) {
188 		if (!nfs_sb_active(server->super))
189 			continue;
190 		rcu_read_unlock();
191 		if (last)
192 			nfs_sb_deactive(last->super);
193 		last = server;
194 		ret = fn(server, data);
195 		if (ret)
196 			goto out;
197 		rcu_read_lock();
198 	}
199 	rcu_read_unlock();
200 out:
201 	if (last)
202 		nfs_sb_deactive(last->super);
203 	return ret;
204 }
205 
206 int nfs_client_for_each_server(struct nfs_client *clp,
207 		int (*fn)(struct nfs_server *, void *),
208 		void *data)
209 {
210 	return __nfs_list_for_each_server(&clp->cl_superblocks, fn, data);
211 }
212 EXPORT_SYMBOL_GPL(nfs_client_for_each_server);
213 
214 /*
215  * Deliver file system statistics to userspace
216  */
217 int nfs_statfs(struct dentry *dentry, struct kstatfs *buf)
218 {
219 	struct nfs_server *server = NFS_SB(dentry->d_sb);
220 	unsigned char blockbits;
221 	unsigned long blockres;
222 	struct nfs_fh *fh = NFS_FH(d_inode(dentry));
223 	struct nfs_fsstat res;
224 	int error = -ENOMEM;
225 
226 	res.fattr = nfs_alloc_fattr();
227 	if (res.fattr == NULL)
228 		goto out_err;
229 
230 	error = server->nfs_client->rpc_ops->statfs(server, fh, &res);
231 	if (unlikely(error == -ESTALE)) {
232 		struct dentry *pd_dentry;
233 
234 		pd_dentry = dget_parent(dentry);
235 		nfs_zap_caches(d_inode(pd_dentry));
236 		dput(pd_dentry);
237 	}
238 	nfs_free_fattr(res.fattr);
239 	if (error < 0)
240 		goto out_err;
241 
242 	buf->f_type = NFS_SUPER_MAGIC;
243 
244 	/*
245 	 * Current versions of glibc do not correctly handle the
246 	 * case where f_frsize != f_bsize.  Eventually we want to
247 	 * report the value of wtmult in this field.
248 	 */
249 	buf->f_frsize = dentry->d_sb->s_blocksize;
250 
251 	/*
252 	 * On most *nix systems, f_blocks, f_bfree, and f_bavail
253 	 * are reported in units of f_frsize.  Linux hasn't had
254 	 * an f_frsize field in its statfs struct until recently,
255 	 * thus historically Linux's sys_statfs reports these
256 	 * fields in units of f_bsize.
257 	 */
258 	buf->f_bsize = dentry->d_sb->s_blocksize;
259 	blockbits = dentry->d_sb->s_blocksize_bits;
260 	blockres = (1 << blockbits) - 1;
261 	buf->f_blocks = (res.tbytes + blockres) >> blockbits;
262 	buf->f_bfree = (res.fbytes + blockres) >> blockbits;
263 	buf->f_bavail = (res.abytes + blockres) >> blockbits;
264 
265 	buf->f_files = res.tfiles;
266 	buf->f_ffree = res.afiles;
267 
268 	buf->f_namelen = server->namelen;
269 
270 	return 0;
271 
272  out_err:
273 	dprintk("%s: statfs error = %d\n", __func__, -error);
274 	return error;
275 }
276 EXPORT_SYMBOL_GPL(nfs_statfs);
277 
278 /*
279  * Map the security flavour number to a name
280  */
281 static const char *nfs_pseudoflavour_to_name(rpc_authflavor_t flavour)
282 {
283 	static const struct {
284 		rpc_authflavor_t flavour;
285 		const char *str;
286 	} sec_flavours[NFS_AUTH_INFO_MAX_FLAVORS] = {
287 		/* update NFS_AUTH_INFO_MAX_FLAVORS when this list changes! */
288 		{ RPC_AUTH_NULL, "null" },
289 		{ RPC_AUTH_UNIX, "sys" },
290 		{ RPC_AUTH_GSS_KRB5, "krb5" },
291 		{ RPC_AUTH_GSS_KRB5I, "krb5i" },
292 		{ RPC_AUTH_GSS_KRB5P, "krb5p" },
293 		{ RPC_AUTH_GSS_LKEY, "lkey" },
294 		{ RPC_AUTH_GSS_LKEYI, "lkeyi" },
295 		{ RPC_AUTH_GSS_LKEYP, "lkeyp" },
296 		{ RPC_AUTH_GSS_SPKM, "spkm" },
297 		{ RPC_AUTH_GSS_SPKMI, "spkmi" },
298 		{ RPC_AUTH_GSS_SPKMP, "spkmp" },
299 		{ UINT_MAX, "unknown" }
300 	};
301 	int i;
302 
303 	for (i = 0; sec_flavours[i].flavour != UINT_MAX; i++) {
304 		if (sec_flavours[i].flavour == flavour)
305 			break;
306 	}
307 	return sec_flavours[i].str;
308 }
309 
310 static void nfs_show_mountd_netid(struct seq_file *m, struct nfs_server *nfss,
311 				  int showdefaults)
312 {
313 	struct sockaddr *sap = (struct sockaddr *) &nfss->mountd_address;
314 	char *proto = NULL;
315 
316 	switch (sap->sa_family) {
317 	case AF_INET:
318 		switch (nfss->mountd_protocol) {
319 		case IPPROTO_UDP:
320 			proto = RPCBIND_NETID_UDP;
321 			break;
322 		case IPPROTO_TCP:
323 			proto = RPCBIND_NETID_TCP;
324 			break;
325 		}
326 		break;
327 	case AF_INET6:
328 		switch (nfss->mountd_protocol) {
329 		case IPPROTO_UDP:
330 			proto = RPCBIND_NETID_UDP6;
331 			break;
332 		case IPPROTO_TCP:
333 			proto = RPCBIND_NETID_TCP6;
334 			break;
335 		}
336 		break;
337 	}
338 	if (proto || showdefaults)
339 		seq_printf(m, ",mountproto=%s", proto ?: "auto");
340 }
341 
342 static void nfs_show_mountd_options(struct seq_file *m, struct nfs_server *nfss,
343 				    int showdefaults)
344 {
345 	struct sockaddr *sap = (struct sockaddr *)&nfss->mountd_address;
346 
347 	if (nfss->flags & NFS_MOUNT_LEGACY_INTERFACE)
348 		return;
349 
350 	switch (sap->sa_family) {
351 	case AF_INET: {
352 		struct sockaddr_in *sin = (struct sockaddr_in *)sap;
353 		seq_printf(m, ",mountaddr=%pI4", &sin->sin_addr.s_addr);
354 		break;
355 	}
356 	case AF_INET6: {
357 		struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sap;
358 		seq_printf(m, ",mountaddr=%pI6c", &sin6->sin6_addr);
359 		break;
360 	}
361 	default:
362 		if (showdefaults)
363 			seq_puts(m, ",mountaddr=unspecified");
364 	}
365 
366 	if (nfss->mountd_version || showdefaults)
367 		seq_printf(m, ",mountvers=%u", nfss->mountd_version);
368 	if ((nfss->mountd_port &&
369 		nfss->mountd_port != (unsigned short)NFS_UNSPEC_PORT) ||
370 		showdefaults)
371 		seq_printf(m, ",mountport=%u", nfss->mountd_port);
372 
373 	nfs_show_mountd_netid(m, nfss, showdefaults);
374 }
375 
376 #if IS_ENABLED(CONFIG_NFS_V4)
377 static void nfs_show_nfsv4_options(struct seq_file *m, struct nfs_server *nfss,
378 				    int showdefaults)
379 {
380 	struct nfs_client *clp = nfss->nfs_client;
381 
382 	seq_printf(m, ",clientaddr=%s", clp->cl_ipaddr);
383 }
384 #else
385 static void nfs_show_nfsv4_options(struct seq_file *m, struct nfs_server *nfss,
386 				    int showdefaults)
387 {
388 }
389 #endif
390 
391 static void nfs_show_nfs_version(struct seq_file *m,
392 		unsigned int version,
393 		unsigned int minorversion)
394 {
395 	seq_printf(m, ",vers=%u", version);
396 	if (version == 4)
397 		seq_printf(m, ".%u", minorversion);
398 }
399 
400 /*
401  * Describe the mount options in force on this server representation
402  */
403 static void nfs_show_mount_options(struct seq_file *m, struct nfs_server *nfss,
404 				   int showdefaults)
405 {
406 	static const struct proc_nfs_info {
407 		int flag;
408 		const char *str;
409 		const char *nostr;
410 	} nfs_info[] = {
411 		{ NFS_MOUNT_SOFT, ",soft", "" },
412 		{ NFS_MOUNT_SOFTERR, ",softerr", "" },
413 		{ NFS_MOUNT_SOFTREVAL, ",softreval", "" },
414 		{ NFS_MOUNT_POSIX, ",posix", "" },
415 		{ NFS_MOUNT_NOCTO, ",nocto", "" },
416 		{ NFS_MOUNT_NOAC, ",noac", "" },
417 		{ NFS_MOUNT_NONLM, ",nolock", "" },
418 		{ NFS_MOUNT_NOACL, ",noacl", "" },
419 		{ NFS_MOUNT_NORDIRPLUS, ",nordirplus", "" },
420 		{ NFS_MOUNT_UNSHARED, ",nosharecache", "" },
421 		{ NFS_MOUNT_NORESVPORT, ",noresvport", "" },
422 		{ 0, NULL, NULL }
423 	};
424 	const struct proc_nfs_info *nfs_infop;
425 	struct nfs_client *clp = nfss->nfs_client;
426 	u32 version = clp->rpc_ops->version;
427 	int local_flock, local_fcntl;
428 
429 	nfs_show_nfs_version(m, version, clp->cl_minorversion);
430 	seq_printf(m, ",rsize=%u", nfss->rsize);
431 	seq_printf(m, ",wsize=%u", nfss->wsize);
432 	if (nfss->bsize != 0)
433 		seq_printf(m, ",bsize=%u", nfss->bsize);
434 	seq_printf(m, ",namlen=%u", nfss->namelen);
435 	if (nfss->acregmin != NFS_DEF_ACREGMIN*HZ || showdefaults)
436 		seq_printf(m, ",acregmin=%u", nfss->acregmin/HZ);
437 	if (nfss->acregmax != NFS_DEF_ACREGMAX*HZ || showdefaults)
438 		seq_printf(m, ",acregmax=%u", nfss->acregmax/HZ);
439 	if (nfss->acdirmin != NFS_DEF_ACDIRMIN*HZ || showdefaults)
440 		seq_printf(m, ",acdirmin=%u", nfss->acdirmin/HZ);
441 	if (nfss->acdirmax != NFS_DEF_ACDIRMAX*HZ || showdefaults)
442 		seq_printf(m, ",acdirmax=%u", nfss->acdirmax/HZ);
443 	if (!(nfss->flags & (NFS_MOUNT_SOFT|NFS_MOUNT_SOFTERR)))
444 			seq_puts(m, ",hard");
445 	for (nfs_infop = nfs_info; nfs_infop->flag; nfs_infop++) {
446 		if (nfss->flags & nfs_infop->flag)
447 			seq_puts(m, nfs_infop->str);
448 		else
449 			seq_puts(m, nfs_infop->nostr);
450 	}
451 	rcu_read_lock();
452 	seq_printf(m, ",proto=%s",
453 		   rpc_peeraddr2str(nfss->client, RPC_DISPLAY_NETID));
454 	rcu_read_unlock();
455 	if (clp->cl_nconnect > 0)
456 		seq_printf(m, ",nconnect=%u", clp->cl_nconnect);
457 	if (version == 4) {
458 		if (nfss->port != NFS_PORT)
459 			seq_printf(m, ",port=%u", nfss->port);
460 	} else
461 		if (nfss->port)
462 			seq_printf(m, ",port=%u", nfss->port);
463 
464 	seq_printf(m, ",timeo=%lu", 10U * nfss->client->cl_timeout->to_initval / HZ);
465 	seq_printf(m, ",retrans=%u", nfss->client->cl_timeout->to_retries);
466 	seq_printf(m, ",sec=%s", nfs_pseudoflavour_to_name(nfss->client->cl_auth->au_flavor));
467 
468 	if (version != 4)
469 		nfs_show_mountd_options(m, nfss, showdefaults);
470 	else
471 		nfs_show_nfsv4_options(m, nfss, showdefaults);
472 
473 	if (nfss->options & NFS_OPTION_FSCACHE)
474 		seq_puts(m, ",fsc");
475 
476 	if (nfss->options & NFS_OPTION_MIGRATION)
477 		seq_puts(m, ",migration");
478 
479 	if (nfss->flags & NFS_MOUNT_LOOKUP_CACHE_NONEG) {
480 		if (nfss->flags & NFS_MOUNT_LOOKUP_CACHE_NONE)
481 			seq_puts(m, ",lookupcache=none");
482 		else
483 			seq_puts(m, ",lookupcache=pos");
484 	}
485 
486 	local_flock = nfss->flags & NFS_MOUNT_LOCAL_FLOCK;
487 	local_fcntl = nfss->flags & NFS_MOUNT_LOCAL_FCNTL;
488 
489 	if (!local_flock && !local_fcntl)
490 		seq_puts(m, ",local_lock=none");
491 	else if (local_flock && local_fcntl)
492 		seq_puts(m, ",local_lock=all");
493 	else if (local_flock)
494 		seq_puts(m, ",local_lock=flock");
495 	else
496 		seq_puts(m, ",local_lock=posix");
497 }
498 
499 /*
500  * Describe the mount options on this VFS mountpoint
501  */
502 int nfs_show_options(struct seq_file *m, struct dentry *root)
503 {
504 	struct nfs_server *nfss = NFS_SB(root->d_sb);
505 
506 	nfs_show_mount_options(m, nfss, 0);
507 
508 	rcu_read_lock();
509 	seq_printf(m, ",addr=%s",
510 			rpc_peeraddr2str(nfss->nfs_client->cl_rpcclient,
511 							RPC_DISPLAY_ADDR));
512 	rcu_read_unlock();
513 
514 	return 0;
515 }
516 EXPORT_SYMBOL_GPL(nfs_show_options);
517 
518 #if IS_ENABLED(CONFIG_NFS_V4)
519 static void show_lease(struct seq_file *m, struct nfs_server *server)
520 {
521 	struct nfs_client *clp = server->nfs_client;
522 	unsigned long expire;
523 
524 	seq_printf(m, ",lease_time=%ld", clp->cl_lease_time / HZ);
525 	expire = clp->cl_last_renewal + clp->cl_lease_time;
526 	seq_printf(m, ",lease_expired=%ld",
527 		   time_after(expire, jiffies) ?  0 : (jiffies - expire) / HZ);
528 }
529 #ifdef CONFIG_NFS_V4_1
530 static void show_sessions(struct seq_file *m, struct nfs_server *server)
531 {
532 	if (nfs4_has_session(server->nfs_client))
533 		seq_puts(m, ",sessions");
534 }
535 #else
536 static void show_sessions(struct seq_file *m, struct nfs_server *server) {}
537 #endif
538 #endif
539 
540 #ifdef CONFIG_NFS_V4_1
541 static void show_pnfs(struct seq_file *m, struct nfs_server *server)
542 {
543 	seq_printf(m, ",pnfs=");
544 	if (server->pnfs_curr_ld)
545 		seq_printf(m, "%s", server->pnfs_curr_ld->name);
546 	else
547 		seq_printf(m, "not configured");
548 }
549 
550 static void show_implementation_id(struct seq_file *m, struct nfs_server *nfss)
551 {
552 	if (nfss->nfs_client && nfss->nfs_client->cl_implid) {
553 		struct nfs41_impl_id *impl_id = nfss->nfs_client->cl_implid;
554 		seq_printf(m, "\n\timpl_id:\tname='%s',domain='%s',"
555 			   "date='%llu,%u'",
556 			   impl_id->name, impl_id->domain,
557 			   impl_id->date.seconds, impl_id->date.nseconds);
558 	}
559 }
560 #else
561 #if IS_ENABLED(CONFIG_NFS_V4)
562 static void show_pnfs(struct seq_file *m, struct nfs_server *server)
563 {
564 }
565 #endif
566 static void show_implementation_id(struct seq_file *m, struct nfs_server *nfss)
567 {
568 }
569 #endif
570 
571 int nfs_show_devname(struct seq_file *m, struct dentry *root)
572 {
573 	char *page = (char *) __get_free_page(GFP_KERNEL);
574 	char *devname, *dummy;
575 	int err = 0;
576 	if (!page)
577 		return -ENOMEM;
578 	devname = nfs_path(&dummy, root, page, PAGE_SIZE, 0);
579 	if (IS_ERR(devname))
580 		err = PTR_ERR(devname);
581 	else
582 		seq_escape(m, devname, " \t\n\\");
583 	free_page((unsigned long)page);
584 	return err;
585 }
586 EXPORT_SYMBOL_GPL(nfs_show_devname);
587 
588 int nfs_show_path(struct seq_file *m, struct dentry *dentry)
589 {
590 	seq_puts(m, "/");
591 	return 0;
592 }
593 EXPORT_SYMBOL_GPL(nfs_show_path);
594 
595 /*
596  * Present statistical information for this VFS mountpoint
597  */
598 int nfs_show_stats(struct seq_file *m, struct dentry *root)
599 {
600 	int i, cpu;
601 	struct nfs_server *nfss = NFS_SB(root->d_sb);
602 	struct rpc_auth *auth = nfss->client->cl_auth;
603 	struct nfs_iostats totals = { };
604 
605 	seq_printf(m, "statvers=%s", NFS_IOSTAT_VERS);
606 
607 	/*
608 	 * Display all mount option settings
609 	 */
610 	seq_puts(m, "\n\topts:\t");
611 	seq_puts(m, sb_rdonly(root->d_sb) ? "ro" : "rw");
612 	seq_puts(m, root->d_sb->s_flags & SB_SYNCHRONOUS ? ",sync" : "");
613 	seq_puts(m, root->d_sb->s_flags & SB_NOATIME ? ",noatime" : "");
614 	seq_puts(m, root->d_sb->s_flags & SB_NODIRATIME ? ",nodiratime" : "");
615 	nfs_show_mount_options(m, nfss, 1);
616 
617 	seq_printf(m, "\n\tage:\t%lu", (jiffies - nfss->mount_time) / HZ);
618 
619 	show_implementation_id(m, nfss);
620 
621 	seq_puts(m, "\n\tcaps:\t");
622 	seq_printf(m, "caps=0x%x", nfss->caps);
623 	seq_printf(m, ",wtmult=%u", nfss->wtmult);
624 	seq_printf(m, ",dtsize=%u", nfss->dtsize);
625 	seq_printf(m, ",bsize=%u", nfss->bsize);
626 	seq_printf(m, ",namlen=%u", nfss->namelen);
627 
628 #if IS_ENABLED(CONFIG_NFS_V4)
629 	if (nfss->nfs_client->rpc_ops->version == 4) {
630 		seq_puts(m, "\n\tnfsv4:\t");
631 		seq_printf(m, "bm0=0x%x", nfss->attr_bitmask[0]);
632 		seq_printf(m, ",bm1=0x%x", nfss->attr_bitmask[1]);
633 		seq_printf(m, ",bm2=0x%x", nfss->attr_bitmask[2]);
634 		seq_printf(m, ",acl=0x%x", nfss->acl_bitmask);
635 		show_sessions(m, nfss);
636 		show_pnfs(m, nfss);
637 		show_lease(m, nfss);
638 	}
639 #endif
640 
641 	/*
642 	 * Display security flavor in effect for this mount
643 	 */
644 	seq_printf(m, "\n\tsec:\tflavor=%u", auth->au_ops->au_flavor);
645 	if (auth->au_flavor)
646 		seq_printf(m, ",pseudoflavor=%u", auth->au_flavor);
647 
648 	/*
649 	 * Display superblock I/O counters
650 	 */
651 	for_each_possible_cpu(cpu) {
652 		struct nfs_iostats *stats;
653 
654 		preempt_disable();
655 		stats = per_cpu_ptr(nfss->io_stats, cpu);
656 
657 		for (i = 0; i < __NFSIOS_COUNTSMAX; i++)
658 			totals.events[i] += stats->events[i];
659 		for (i = 0; i < __NFSIOS_BYTESMAX; i++)
660 			totals.bytes[i] += stats->bytes[i];
661 #ifdef CONFIG_NFS_FSCACHE
662 		for (i = 0; i < __NFSIOS_FSCACHEMAX; i++)
663 			totals.fscache[i] += stats->fscache[i];
664 #endif
665 
666 		preempt_enable();
667 	}
668 
669 	seq_puts(m, "\n\tevents:\t");
670 	for (i = 0; i < __NFSIOS_COUNTSMAX; i++)
671 		seq_printf(m, "%lu ", totals.events[i]);
672 	seq_puts(m, "\n\tbytes:\t");
673 	for (i = 0; i < __NFSIOS_BYTESMAX; i++)
674 		seq_printf(m, "%Lu ", totals.bytes[i]);
675 #ifdef CONFIG_NFS_FSCACHE
676 	if (nfss->options & NFS_OPTION_FSCACHE) {
677 		seq_puts(m, "\n\tfsc:\t");
678 		for (i = 0; i < __NFSIOS_FSCACHEMAX; i++)
679 			seq_printf(m, "%Lu ", totals.fscache[i]);
680 	}
681 #endif
682 	seq_putc(m, '\n');
683 
684 	rpc_clnt_show_stats(m, nfss->client);
685 
686 	return 0;
687 }
688 EXPORT_SYMBOL_GPL(nfs_show_stats);
689 
690 /*
691  * Begin unmount by attempting to remove all automounted mountpoints we added
692  * in response to xdev traversals and referrals
693  */
694 void nfs_umount_begin(struct super_block *sb)
695 {
696 	struct nfs_server *server;
697 	struct rpc_clnt *rpc;
698 
699 	server = NFS_SB(sb);
700 	/* -EIO all pending I/O */
701 	rpc = server->client_acl;
702 	if (!IS_ERR(rpc))
703 		rpc_killall_tasks(rpc);
704 	rpc = server->client;
705 	if (!IS_ERR(rpc))
706 		rpc_killall_tasks(rpc);
707 }
708 EXPORT_SYMBOL_GPL(nfs_umount_begin);
709 
710 /*
711  * Return true if 'match' is in auth_info or auth_info is empty.
712  * Return false otherwise.
713  */
714 bool nfs_auth_info_match(const struct nfs_auth_info *auth_info,
715 			 rpc_authflavor_t match)
716 {
717 	int i;
718 
719 	if (!auth_info->flavor_len)
720 		return true;
721 
722 	for (i = 0; i < auth_info->flavor_len; i++) {
723 		if (auth_info->flavors[i] == match)
724 			return true;
725 	}
726 	return false;
727 }
728 EXPORT_SYMBOL_GPL(nfs_auth_info_match);
729 
730 /*
731  * Ensure that a specified authtype in ctx->auth_info is supported by
732  * the server. Returns 0 and sets ctx->selected_flavor if it's ok, and
733  * -EACCES if not.
734  */
735 static int nfs_verify_authflavors(struct nfs_fs_context *ctx,
736 				  rpc_authflavor_t *server_authlist,
737 				  unsigned int count)
738 {
739 	rpc_authflavor_t flavor = RPC_AUTH_MAXFLAVOR;
740 	bool found_auth_null = false;
741 	unsigned int i;
742 
743 	/*
744 	 * If the sec= mount option is used, the specified flavor or AUTH_NULL
745 	 * must be in the list returned by the server.
746 	 *
747 	 * AUTH_NULL has a special meaning when it's in the server list - it
748 	 * means that the server will ignore the rpc creds, so any flavor
749 	 * can be used but still use the sec= that was specified.
750 	 *
751 	 * Note also that the MNT procedure in MNTv1 does not return a list
752 	 * of supported security flavors. In this case, nfs_mount() fabricates
753 	 * a security flavor list containing just AUTH_NULL.
754 	 */
755 	for (i = 0; i < count; i++) {
756 		flavor = server_authlist[i];
757 
758 		if (nfs_auth_info_match(&ctx->auth_info, flavor))
759 			goto out;
760 
761 		if (flavor == RPC_AUTH_NULL)
762 			found_auth_null = true;
763 	}
764 
765 	if (found_auth_null) {
766 		flavor = ctx->auth_info.flavors[0];
767 		goto out;
768 	}
769 
770 	dfprintk(MOUNT,
771 		 "NFS: specified auth flavors not supported by server\n");
772 	return -EACCES;
773 
774 out:
775 	ctx->selected_flavor = flavor;
776 	dfprintk(MOUNT, "NFS: using auth flavor %u\n", ctx->selected_flavor);
777 	return 0;
778 }
779 
780 /*
781  * Use the remote server's MOUNT service to request the NFS file handle
782  * corresponding to the provided path.
783  */
784 static int nfs_request_mount(struct fs_context *fc,
785 			     struct nfs_fh *root_fh,
786 			     rpc_authflavor_t *server_authlist,
787 			     unsigned int *server_authlist_len)
788 {
789 	struct nfs_fs_context *ctx = nfs_fc2context(fc);
790 	struct nfs_mount_request request = {
791 		.sap		= (struct sockaddr *)
792 						&ctx->mount_server.address,
793 		.dirpath	= ctx->nfs_server.export_path,
794 		.protocol	= ctx->mount_server.protocol,
795 		.fh		= root_fh,
796 		.noresvport	= ctx->flags & NFS_MOUNT_NORESVPORT,
797 		.auth_flav_len	= server_authlist_len,
798 		.auth_flavs	= server_authlist,
799 		.net		= fc->net_ns,
800 	};
801 	int status;
802 
803 	if (ctx->mount_server.version == 0) {
804 		switch (ctx->version) {
805 			default:
806 				ctx->mount_server.version = NFS_MNT3_VERSION;
807 				break;
808 			case 2:
809 				ctx->mount_server.version = NFS_MNT_VERSION;
810 		}
811 	}
812 	request.version = ctx->mount_server.version;
813 
814 	if (ctx->mount_server.hostname)
815 		request.hostname = ctx->mount_server.hostname;
816 	else
817 		request.hostname = ctx->nfs_server.hostname;
818 
819 	/*
820 	 * Construct the mount server's address.
821 	 */
822 	if (ctx->mount_server.address.sa_family == AF_UNSPEC) {
823 		memcpy(request.sap, &ctx->nfs_server.address,
824 		       ctx->nfs_server.addrlen);
825 		ctx->mount_server.addrlen = ctx->nfs_server.addrlen;
826 	}
827 	request.salen = ctx->mount_server.addrlen;
828 	nfs_set_port(request.sap, &ctx->mount_server.port, 0);
829 
830 	/*
831 	 * Now ask the mount server to map our export path
832 	 * to a file handle.
833 	 */
834 	status = nfs_mount(&request);
835 	if (status != 0) {
836 		dfprintk(MOUNT, "NFS: unable to mount server %s, error %d\n",
837 				request.hostname, status);
838 		return status;
839 	}
840 
841 	return 0;
842 }
843 
844 static struct nfs_server *nfs_try_mount_request(struct fs_context *fc)
845 {
846 	struct nfs_fs_context *ctx = nfs_fc2context(fc);
847 	int status;
848 	unsigned int i;
849 	bool tried_auth_unix = false;
850 	bool auth_null_in_list = false;
851 	struct nfs_server *server = ERR_PTR(-EACCES);
852 	rpc_authflavor_t authlist[NFS_MAX_SECFLAVORS];
853 	unsigned int authlist_len = ARRAY_SIZE(authlist);
854 
855 	status = nfs_request_mount(fc, ctx->mntfh, authlist, &authlist_len);
856 	if (status)
857 		return ERR_PTR(status);
858 
859 	/*
860 	 * Was a sec= authflavor specified in the options? First, verify
861 	 * whether the server supports it, and then just try to use it if so.
862 	 */
863 	if (ctx->auth_info.flavor_len > 0) {
864 		status = nfs_verify_authflavors(ctx, authlist, authlist_len);
865 		dfprintk(MOUNT, "NFS: using auth flavor %u\n",
866 			 ctx->selected_flavor);
867 		if (status)
868 			return ERR_PTR(status);
869 		return ctx->nfs_mod->rpc_ops->create_server(fc);
870 	}
871 
872 	/*
873 	 * No sec= option was provided. RFC 2623, section 2.7 suggests we
874 	 * SHOULD prefer the flavor listed first. However, some servers list
875 	 * AUTH_NULL first. Avoid ever choosing AUTH_NULL.
876 	 */
877 	for (i = 0; i < authlist_len; ++i) {
878 		rpc_authflavor_t flavor;
879 		struct rpcsec_gss_info info;
880 
881 		flavor = authlist[i];
882 		switch (flavor) {
883 		case RPC_AUTH_UNIX:
884 			tried_auth_unix = true;
885 			break;
886 		case RPC_AUTH_NULL:
887 			auth_null_in_list = true;
888 			continue;
889 		default:
890 			if (rpcauth_get_gssinfo(flavor, &info) != 0)
891 				continue;
892 			/* Fallthrough */
893 		}
894 		dfprintk(MOUNT, "NFS: attempting to use auth flavor %u\n", flavor);
895 		ctx->selected_flavor = flavor;
896 		server = ctx->nfs_mod->rpc_ops->create_server(fc);
897 		if (!IS_ERR(server))
898 			return server;
899 	}
900 
901 	/*
902 	 * Nothing we tried so far worked. At this point, give up if we've
903 	 * already tried AUTH_UNIX or if the server's list doesn't contain
904 	 * AUTH_NULL
905 	 */
906 	if (tried_auth_unix || !auth_null_in_list)
907 		return server;
908 
909 	/* Last chance! Try AUTH_UNIX */
910 	dfprintk(MOUNT, "NFS: attempting to use auth flavor %u\n", RPC_AUTH_UNIX);
911 	ctx->selected_flavor = RPC_AUTH_UNIX;
912 	return ctx->nfs_mod->rpc_ops->create_server(fc);
913 }
914 
915 int nfs_try_get_tree(struct fs_context *fc)
916 {
917 	struct nfs_fs_context *ctx = nfs_fc2context(fc);
918 
919 	if (ctx->need_mount)
920 		ctx->server = nfs_try_mount_request(fc);
921 	else
922 		ctx->server = ctx->nfs_mod->rpc_ops->create_server(fc);
923 
924 	return nfs_get_tree_common(fc);
925 }
926 EXPORT_SYMBOL_GPL(nfs_try_get_tree);
927 
928 
929 #define NFS_REMOUNT_CMP_FLAGMASK ~(NFS_MOUNT_INTR \
930 		| NFS_MOUNT_SECURE \
931 		| NFS_MOUNT_TCP \
932 		| NFS_MOUNT_VER3 \
933 		| NFS_MOUNT_KERBEROS \
934 		| NFS_MOUNT_NONLM \
935 		| NFS_MOUNT_BROKEN_SUID \
936 		| NFS_MOUNT_STRICTLOCK \
937 		| NFS_MOUNT_LEGACY_INTERFACE)
938 
939 #define NFS_MOUNT_CMP_FLAGMASK (NFS_REMOUNT_CMP_FLAGMASK & \
940 		~(NFS_MOUNT_UNSHARED | NFS_MOUNT_NORESVPORT))
941 
942 static int
943 nfs_compare_remount_data(struct nfs_server *nfss,
944 			 struct nfs_fs_context *ctx)
945 {
946 	if ((ctx->flags ^ nfss->flags) & NFS_REMOUNT_CMP_FLAGMASK ||
947 	    ctx->rsize != nfss->rsize ||
948 	    ctx->wsize != nfss->wsize ||
949 	    ctx->version != nfss->nfs_client->rpc_ops->version ||
950 	    ctx->minorversion != nfss->nfs_client->cl_minorversion ||
951 	    ctx->retrans != nfss->client->cl_timeout->to_retries ||
952 	    !nfs_auth_info_match(&ctx->auth_info, nfss->client->cl_auth->au_flavor) ||
953 	    ctx->acregmin != nfss->acregmin / HZ ||
954 	    ctx->acregmax != nfss->acregmax / HZ ||
955 	    ctx->acdirmin != nfss->acdirmin / HZ ||
956 	    ctx->acdirmax != nfss->acdirmax / HZ ||
957 	    ctx->timeo != (10U * nfss->client->cl_timeout->to_initval / HZ) ||
958 	    (ctx->options & NFS_OPTION_FSCACHE) != (nfss->options & NFS_OPTION_FSCACHE) ||
959 	    ctx->nfs_server.port != nfss->port ||
960 	    ctx->nfs_server.addrlen != nfss->nfs_client->cl_addrlen ||
961 	    !rpc_cmp_addr((struct sockaddr *)&ctx->nfs_server.address,
962 			  (struct sockaddr *)&nfss->nfs_client->cl_addr))
963 		return -EINVAL;
964 
965 	return 0;
966 }
967 
968 int nfs_reconfigure(struct fs_context *fc)
969 {
970 	struct nfs_fs_context *ctx = nfs_fc2context(fc);
971 	struct super_block *sb = fc->root->d_sb;
972 	struct nfs_server *nfss = sb->s_fs_info;
973 
974 	sync_filesystem(sb);
975 
976 	/*
977 	 * Userspace mount programs that send binary options generally send
978 	 * them populated with default values. We have no way to know which
979 	 * ones were explicitly specified. Fall back to legacy behavior and
980 	 * just return success.
981 	 */
982 	if (ctx->skip_reconfig_option_check)
983 		return 0;
984 
985 	/*
986 	 * noac is a special case. It implies -o sync, but that's not
987 	 * necessarily reflected in the mtab options. reconfigure_super
988 	 * will clear SB_SYNCHRONOUS if -o sync wasn't specified in the
989 	 * remount options, so we have to explicitly reset it.
990 	 */
991 	if (ctx->flags & NFS_MOUNT_NOAC) {
992 		fc->sb_flags |= SB_SYNCHRONOUS;
993 		fc->sb_flags_mask |= SB_SYNCHRONOUS;
994 	}
995 
996 	/* compare new mount options with old ones */
997 	return nfs_compare_remount_data(nfss, ctx);
998 }
999 EXPORT_SYMBOL_GPL(nfs_reconfigure);
1000 
1001 /*
1002  * Finish setting up an NFS superblock
1003  */
1004 static void nfs_fill_super(struct super_block *sb, struct nfs_fs_context *ctx)
1005 {
1006 	struct nfs_server *server = NFS_SB(sb);
1007 
1008 	sb->s_blocksize_bits = 0;
1009 	sb->s_blocksize = 0;
1010 	sb->s_xattr = server->nfs_client->cl_nfs_mod->xattr;
1011 	sb->s_op = server->nfs_client->cl_nfs_mod->sops;
1012 	if (ctx && ctx->bsize)
1013 		sb->s_blocksize = nfs_block_size(ctx->bsize, &sb->s_blocksize_bits);
1014 
1015 	if (server->nfs_client->rpc_ops->version != 2) {
1016 		/* The VFS shouldn't apply the umask to mode bits. We will do
1017 		 * so ourselves when necessary.
1018 		 */
1019 		sb->s_flags |= SB_POSIXACL;
1020 		sb->s_time_gran = 1;
1021 		sb->s_export_op = &nfs_export_ops;
1022 	} else
1023 		sb->s_time_gran = 1000;
1024 
1025 	if (server->nfs_client->rpc_ops->version != 4) {
1026 		sb->s_time_min = 0;
1027 		sb->s_time_max = U32_MAX;
1028 	} else {
1029 		sb->s_time_min = S64_MIN;
1030 		sb->s_time_max = S64_MAX;
1031 	}
1032 
1033 	sb->s_magic = NFS_SUPER_MAGIC;
1034 
1035 	/* We probably want something more informative here */
1036 	snprintf(sb->s_id, sizeof(sb->s_id),
1037 		 "%u:%u", MAJOR(sb->s_dev), MINOR(sb->s_dev));
1038 
1039 	if (sb->s_blocksize == 0)
1040 		sb->s_blocksize = nfs_block_bits(server->wsize,
1041 						 &sb->s_blocksize_bits);
1042 
1043 	nfs_super_set_maxbytes(sb, server->maxfilesize);
1044 }
1045 
1046 static int nfs_compare_mount_options(const struct super_block *s, const struct nfs_server *b,
1047 				     const struct fs_context *fc)
1048 {
1049 	const struct nfs_server *a = s->s_fs_info;
1050 	const struct rpc_clnt *clnt_a = a->client;
1051 	const struct rpc_clnt *clnt_b = b->client;
1052 
1053 	if ((s->s_flags & NFS_SB_MASK) != (fc->sb_flags & NFS_SB_MASK))
1054 		goto Ebusy;
1055 	if (a->nfs_client != b->nfs_client)
1056 		goto Ebusy;
1057 	if ((a->flags ^ b->flags) & NFS_MOUNT_CMP_FLAGMASK)
1058 		goto Ebusy;
1059 	if (a->wsize != b->wsize)
1060 		goto Ebusy;
1061 	if (a->rsize != b->rsize)
1062 		goto Ebusy;
1063 	if (a->acregmin != b->acregmin)
1064 		goto Ebusy;
1065 	if (a->acregmax != b->acregmax)
1066 		goto Ebusy;
1067 	if (a->acdirmin != b->acdirmin)
1068 		goto Ebusy;
1069 	if (a->acdirmax != b->acdirmax)
1070 		goto Ebusy;
1071 	if (clnt_a->cl_auth->au_flavor != clnt_b->cl_auth->au_flavor)
1072 		goto Ebusy;
1073 	return 1;
1074 Ebusy:
1075 	return 0;
1076 }
1077 
1078 static int nfs_set_super(struct super_block *s, struct fs_context *fc)
1079 {
1080 	struct nfs_server *server = fc->s_fs_info;
1081 	int ret;
1082 
1083 	s->s_d_op = server->nfs_client->rpc_ops->dentry_ops;
1084 	ret = set_anon_super(s, server);
1085 	if (ret == 0)
1086 		server->s_dev = s->s_dev;
1087 	return ret;
1088 }
1089 
1090 static int nfs_compare_super_address(struct nfs_server *server1,
1091 				     struct nfs_server *server2)
1092 {
1093 	struct sockaddr *sap1, *sap2;
1094 	struct rpc_xprt *xprt1 = server1->client->cl_xprt;
1095 	struct rpc_xprt *xprt2 = server2->client->cl_xprt;
1096 
1097 	if (!net_eq(xprt1->xprt_net, xprt2->xprt_net))
1098 		return 0;
1099 
1100 	sap1 = (struct sockaddr *)&server1->nfs_client->cl_addr;
1101 	sap2 = (struct sockaddr *)&server2->nfs_client->cl_addr;
1102 
1103 	if (sap1->sa_family != sap2->sa_family)
1104 		return 0;
1105 
1106 	switch (sap1->sa_family) {
1107 	case AF_INET: {
1108 		struct sockaddr_in *sin1 = (struct sockaddr_in *)sap1;
1109 		struct sockaddr_in *sin2 = (struct sockaddr_in *)sap2;
1110 		if (sin1->sin_addr.s_addr != sin2->sin_addr.s_addr)
1111 			return 0;
1112 		if (sin1->sin_port != sin2->sin_port)
1113 			return 0;
1114 		break;
1115 	}
1116 	case AF_INET6: {
1117 		struct sockaddr_in6 *sin1 = (struct sockaddr_in6 *)sap1;
1118 		struct sockaddr_in6 *sin2 = (struct sockaddr_in6 *)sap2;
1119 		if (!ipv6_addr_equal(&sin1->sin6_addr, &sin2->sin6_addr))
1120 			return 0;
1121 		if (sin1->sin6_port != sin2->sin6_port)
1122 			return 0;
1123 		break;
1124 	}
1125 	default:
1126 		return 0;
1127 	}
1128 
1129 	return 1;
1130 }
1131 
1132 static int nfs_compare_userns(const struct nfs_server *old,
1133 		const struct nfs_server *new)
1134 {
1135 	const struct user_namespace *oldns = &init_user_ns;
1136 	const struct user_namespace *newns = &init_user_ns;
1137 
1138 	if (old->client && old->client->cl_cred)
1139 		oldns = old->client->cl_cred->user_ns;
1140 	if (new->client && new->client->cl_cred)
1141 		newns = new->client->cl_cred->user_ns;
1142 	if (oldns != newns)
1143 		return 0;
1144 	return 1;
1145 }
1146 
1147 static int nfs_compare_super(struct super_block *sb, struct fs_context *fc)
1148 {
1149 	struct nfs_server *server = fc->s_fs_info, *old = NFS_SB(sb);
1150 
1151 	if (!nfs_compare_super_address(old, server))
1152 		return 0;
1153 	/* Note: NFS_MOUNT_UNSHARED == NFS4_MOUNT_UNSHARED */
1154 	if (old->flags & NFS_MOUNT_UNSHARED)
1155 		return 0;
1156 	if (memcmp(&old->fsid, &server->fsid, sizeof(old->fsid)) != 0)
1157 		return 0;
1158 	if (!nfs_compare_userns(old, server))
1159 		return 0;
1160 	return nfs_compare_mount_options(sb, server, fc);
1161 }
1162 
1163 #ifdef CONFIG_NFS_FSCACHE
1164 static void nfs_get_cache_cookie(struct super_block *sb,
1165 				 struct nfs_fs_context *ctx)
1166 {
1167 	struct nfs_server *nfss = NFS_SB(sb);
1168 	char *uniq = NULL;
1169 	int ulen = 0;
1170 
1171 	nfss->fscache_key = NULL;
1172 	nfss->fscache = NULL;
1173 
1174 	if (!ctx)
1175 		return;
1176 
1177 	if (ctx->clone_data.sb) {
1178 		struct nfs_server *mnt_s = NFS_SB(ctx->clone_data.sb);
1179 		if (!(mnt_s->options & NFS_OPTION_FSCACHE))
1180 			return;
1181 		if (mnt_s->fscache_key) {
1182 			uniq = mnt_s->fscache_key->key.uniquifier;
1183 			ulen = mnt_s->fscache_key->key.uniq_len;
1184 		}
1185 	} else {
1186 		if (!(ctx->options & NFS_OPTION_FSCACHE))
1187 			return;
1188 		if (ctx->fscache_uniq) {
1189 			uniq = ctx->fscache_uniq;
1190 			ulen = strlen(ctx->fscache_uniq);
1191 		}
1192 		return;
1193 	}
1194 
1195 	nfs_fscache_get_super_cookie(sb, uniq, ulen);
1196 }
1197 #else
1198 static void nfs_get_cache_cookie(struct super_block *sb,
1199 				 struct nfs_fs_context *ctx)
1200 {
1201 }
1202 #endif
1203 
1204 static void nfs_set_readahead(struct backing_dev_info *bdi,
1205 			      unsigned long iomax_pages)
1206 {
1207 	bdi->ra_pages = VM_READAHEAD_PAGES;
1208 	bdi->io_pages = iomax_pages;
1209 }
1210 
1211 int nfs_get_tree_common(struct fs_context *fc)
1212 {
1213 	struct nfs_fs_context *ctx = nfs_fc2context(fc);
1214 	struct super_block *s;
1215 	int (*compare_super)(struct super_block *, struct fs_context *) = nfs_compare_super;
1216 	struct nfs_server *server = ctx->server;
1217 	int error;
1218 
1219 	ctx->server = NULL;
1220 	if (IS_ERR(server))
1221 		return PTR_ERR(server);
1222 
1223 	if (server->flags & NFS_MOUNT_UNSHARED)
1224 		compare_super = NULL;
1225 
1226 	/* -o noac implies -o sync */
1227 	if (server->flags & NFS_MOUNT_NOAC)
1228 		fc->sb_flags |= SB_SYNCHRONOUS;
1229 
1230 	if (ctx->clone_data.sb)
1231 		if (ctx->clone_data.sb->s_flags & SB_SYNCHRONOUS)
1232 			fc->sb_flags |= SB_SYNCHRONOUS;
1233 
1234 	if (server->caps & NFS_CAP_SECURITY_LABEL)
1235 		fc->lsm_flags |= SECURITY_LSM_NATIVE_LABELS;
1236 
1237 	/* Get a superblock - note that we may end up sharing one that already exists */
1238 	fc->s_fs_info = server;
1239 	s = sget_fc(fc, compare_super, nfs_set_super);
1240 	fc->s_fs_info = NULL;
1241 	if (IS_ERR(s)) {
1242 		error = PTR_ERR(s);
1243 		nfs_errorf(fc, "NFS: Couldn't get superblock");
1244 		goto out_err_nosb;
1245 	}
1246 
1247 	if (s->s_fs_info != server) {
1248 		nfs_free_server(server);
1249 		server = NULL;
1250 	} else {
1251 		error = super_setup_bdi_name(s, "%u:%u", MAJOR(server->s_dev),
1252 					     MINOR(server->s_dev));
1253 		if (error)
1254 			goto error_splat_super;
1255 		nfs_set_readahead(s->s_bdi, server->rpages);
1256 		server->super = s;
1257 	}
1258 
1259 	if (!s->s_root) {
1260 		unsigned bsize = ctx->clone_data.inherited_bsize;
1261 		/* initial superblock/root creation */
1262 		nfs_fill_super(s, ctx);
1263 		if (bsize) {
1264 			s->s_blocksize_bits = bsize;
1265 			s->s_blocksize = 1U << bsize;
1266 		}
1267 		nfs_get_cache_cookie(s, ctx);
1268 	}
1269 
1270 	error = nfs_get_root(s, fc);
1271 	if (error < 0) {
1272 		nfs_errorf(fc, "NFS: Couldn't get root dentry");
1273 		goto error_splat_super;
1274 	}
1275 
1276 	s->s_flags |= SB_ACTIVE;
1277 	error = 0;
1278 
1279 out:
1280 	return error;
1281 
1282 out_err_nosb:
1283 	nfs_free_server(server);
1284 	goto out;
1285 error_splat_super:
1286 	deactivate_locked_super(s);
1287 	goto out;
1288 }
1289 
1290 /*
1291  * Destroy an NFS2/3 superblock
1292  */
1293 void nfs_kill_super(struct super_block *s)
1294 {
1295 	struct nfs_server *server = NFS_SB(s);
1296 	dev_t dev = s->s_dev;
1297 
1298 	generic_shutdown_super(s);
1299 
1300 	nfs_fscache_release_super_cookie(s);
1301 
1302 	nfs_free_server(server);
1303 	free_anon_bdev(dev);
1304 }
1305 EXPORT_SYMBOL_GPL(nfs_kill_super);
1306 
1307 #if IS_ENABLED(CONFIG_NFS_V4)
1308 
1309 /*
1310  * NFS v4 module parameters need to stay in the
1311  * NFS client for backwards compatibility
1312  */
1313 unsigned int nfs_callback_set_tcpport;
1314 unsigned short nfs_callback_nr_threads;
1315 /* Default cache timeout is 10 minutes */
1316 unsigned int nfs_idmap_cache_timeout = 600;
1317 /* Turn off NFSv4 uid/gid mapping when using AUTH_SYS */
1318 bool nfs4_disable_idmapping = true;
1319 unsigned short max_session_slots = NFS4_DEF_SLOT_TABLE_SIZE;
1320 unsigned short max_session_cb_slots = NFS4_DEF_CB_SLOT_TABLE_SIZE;
1321 unsigned short send_implementation_id = 1;
1322 char nfs4_client_id_uniquifier[NFS4_CLIENT_ID_UNIQ_LEN] = "";
1323 bool recover_lost_locks = false;
1324 
1325 EXPORT_SYMBOL_GPL(nfs_callback_nr_threads);
1326 EXPORT_SYMBOL_GPL(nfs_callback_set_tcpport);
1327 EXPORT_SYMBOL_GPL(nfs_idmap_cache_timeout);
1328 EXPORT_SYMBOL_GPL(nfs4_disable_idmapping);
1329 EXPORT_SYMBOL_GPL(max_session_slots);
1330 EXPORT_SYMBOL_GPL(max_session_cb_slots);
1331 EXPORT_SYMBOL_GPL(send_implementation_id);
1332 EXPORT_SYMBOL_GPL(nfs4_client_id_uniquifier);
1333 EXPORT_SYMBOL_GPL(recover_lost_locks);
1334 
1335 #define NFS_CALLBACK_MAXPORTNR (65535U)
1336 
1337 static int param_set_portnr(const char *val, const struct kernel_param *kp)
1338 {
1339 	unsigned long num;
1340 	int ret;
1341 
1342 	if (!val)
1343 		return -EINVAL;
1344 	ret = kstrtoul(val, 0, &num);
1345 	if (ret || num > NFS_CALLBACK_MAXPORTNR)
1346 		return -EINVAL;
1347 	*((unsigned int *)kp->arg) = num;
1348 	return 0;
1349 }
1350 static const struct kernel_param_ops param_ops_portnr = {
1351 	.set = param_set_portnr,
1352 	.get = param_get_uint,
1353 };
1354 #define param_check_portnr(name, p) __param_check(name, p, unsigned int);
1355 
1356 module_param_named(callback_tcpport, nfs_callback_set_tcpport, portnr, 0644);
1357 module_param_named(callback_nr_threads, nfs_callback_nr_threads, ushort, 0644);
1358 MODULE_PARM_DESC(callback_nr_threads, "Number of threads that will be "
1359 		"assigned to the NFSv4 callback channels.");
1360 module_param(nfs_idmap_cache_timeout, int, 0644);
1361 module_param(nfs4_disable_idmapping, bool, 0644);
1362 module_param_string(nfs4_unique_id, nfs4_client_id_uniquifier,
1363 			NFS4_CLIENT_ID_UNIQ_LEN, 0600);
1364 MODULE_PARM_DESC(nfs4_disable_idmapping,
1365 		"Turn off NFSv4 idmapping when using 'sec=sys'");
1366 module_param(max_session_slots, ushort, 0644);
1367 MODULE_PARM_DESC(max_session_slots, "Maximum number of outstanding NFSv4.1 "
1368 		"requests the client will negotiate");
1369 module_param(max_session_cb_slots, ushort, 0644);
1370 MODULE_PARM_DESC(max_session_cb_slots, "Maximum number of parallel NFSv4.1 "
1371 		"callbacks the client will process for a given server");
1372 module_param(send_implementation_id, ushort, 0644);
1373 MODULE_PARM_DESC(send_implementation_id,
1374 		"Send implementation ID with NFSv4.1 exchange_id");
1375 MODULE_PARM_DESC(nfs4_unique_id, "nfs_client_id4 uniquifier string");
1376 
1377 module_param(recover_lost_locks, bool, 0644);
1378 MODULE_PARM_DESC(recover_lost_locks,
1379 		 "If the server reports that a lock might be lost, "
1380 		 "try to recover it risking data corruption.");
1381 
1382 
1383 #endif /* CONFIG_NFS_V4 */
1384