xref: /linux/fs/nfs/super.c (revision a67ff6a54095e27093ea501fb143fefe51a536c2)
1 /*
2  *  linux/fs/nfs/super.c
3  *
4  *  Copyright (C) 1992  Rick Sladkey
5  *
6  *  nfs superblock handling functions
7  *
8  *  Modularised by Alan Cox <alan@lxorguk.ukuu.org.uk>, while hacking some
9  *  experimental NFS changes. Modularisation taken straight from SYS5 fs.
10  *
11  *  Change to nfs_read_super() to permit NFS mounts to multi-homed hosts.
12  *  J.S.Peatfield@damtp.cam.ac.uk
13  *
14  *  Split from inode.c by David Howells <dhowells@redhat.com>
15  *
16  * - superblocks are indexed on server only - all inodes, dentries, etc. associated with a
17  *   particular server are held in the same superblock
18  * - NFS superblocks can have several effective roots to the dentry tree
19  * - directory type roots are spliced into the tree when a path from one root reaches the root
20  *   of another (see nfs_lookup())
21  */
22 
23 #include <linux/module.h>
24 #include <linux/init.h>
25 
26 #include <linux/time.h>
27 #include <linux/kernel.h>
28 #include <linux/mm.h>
29 #include <linux/string.h>
30 #include <linux/stat.h>
31 #include <linux/errno.h>
32 #include <linux/unistd.h>
33 #include <linux/sunrpc/clnt.h>
34 #include <linux/sunrpc/stats.h>
35 #include <linux/sunrpc/metrics.h>
36 #include <linux/sunrpc/xprtsock.h>
37 #include <linux/sunrpc/xprtrdma.h>
38 #include <linux/nfs_fs.h>
39 #include <linux/nfs_mount.h>
40 #include <linux/nfs4_mount.h>
41 #include <linux/lockd/bind.h>
42 #include <linux/seq_file.h>
43 #include <linux/mount.h>
44 #include <linux/mnt_namespace.h>
45 #include <linux/namei.h>
46 #include <linux/nfs_idmap.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 
57 #include <asm/system.h>
58 #include <asm/uaccess.h>
59 
60 #include "nfs4_fs.h"
61 #include "callback.h"
62 #include "delegation.h"
63 #include "iostat.h"
64 #include "internal.h"
65 #include "fscache.h"
66 #include "pnfs.h"
67 
68 #define NFSDBG_FACILITY		NFSDBG_VFS
69 
70 #ifdef CONFIG_NFS_V3
71 #define NFS_DEFAULT_VERSION 3
72 #else
73 #define NFS_DEFAULT_VERSION 2
74 #endif
75 
76 enum {
77 	/* Mount options that take no arguments */
78 	Opt_soft, Opt_hard,
79 	Opt_posix, Opt_noposix,
80 	Opt_cto, Opt_nocto,
81 	Opt_ac, Opt_noac,
82 	Opt_lock, Opt_nolock,
83 	Opt_v2, Opt_v3, Opt_v4,
84 	Opt_udp, Opt_tcp, Opt_rdma,
85 	Opt_acl, Opt_noacl,
86 	Opt_rdirplus, Opt_nordirplus,
87 	Opt_sharecache, Opt_nosharecache,
88 	Opt_resvport, Opt_noresvport,
89 	Opt_fscache, Opt_nofscache,
90 
91 	/* Mount options that take integer arguments */
92 	Opt_port,
93 	Opt_rsize, Opt_wsize, Opt_bsize,
94 	Opt_timeo, Opt_retrans,
95 	Opt_acregmin, Opt_acregmax,
96 	Opt_acdirmin, Opt_acdirmax,
97 	Opt_actimeo,
98 	Opt_namelen,
99 	Opt_mountport,
100 	Opt_mountvers,
101 	Opt_nfsvers,
102 	Opt_minorversion,
103 
104 	/* Mount options that take string arguments */
105 	Opt_sec, Opt_proto, Opt_mountproto, Opt_mounthost,
106 	Opt_addr, Opt_mountaddr, Opt_clientaddr,
107 	Opt_lookupcache,
108 	Opt_fscache_uniq,
109 	Opt_local_lock,
110 
111 	/* Special mount options */
112 	Opt_userspace, Opt_deprecated, Opt_sloppy,
113 
114 	Opt_err
115 };
116 
117 static const match_table_t nfs_mount_option_tokens = {
118 	{ Opt_userspace, "bg" },
119 	{ Opt_userspace, "fg" },
120 	{ Opt_userspace, "retry=%s" },
121 
122 	{ Opt_sloppy, "sloppy" },
123 
124 	{ Opt_soft, "soft" },
125 	{ Opt_hard, "hard" },
126 	{ Opt_deprecated, "intr" },
127 	{ Opt_deprecated, "nointr" },
128 	{ Opt_posix, "posix" },
129 	{ Opt_noposix, "noposix" },
130 	{ Opt_cto, "cto" },
131 	{ Opt_nocto, "nocto" },
132 	{ Opt_ac, "ac" },
133 	{ Opt_noac, "noac" },
134 	{ Opt_lock, "lock" },
135 	{ Opt_nolock, "nolock" },
136 	{ Opt_v2, "v2" },
137 	{ Opt_v3, "v3" },
138 	{ Opt_v4, "v4" },
139 	{ Opt_udp, "udp" },
140 	{ Opt_tcp, "tcp" },
141 	{ Opt_rdma, "rdma" },
142 	{ Opt_acl, "acl" },
143 	{ Opt_noacl, "noacl" },
144 	{ Opt_rdirplus, "rdirplus" },
145 	{ Opt_nordirplus, "nordirplus" },
146 	{ Opt_sharecache, "sharecache" },
147 	{ Opt_nosharecache, "nosharecache" },
148 	{ Opt_resvport, "resvport" },
149 	{ Opt_noresvport, "noresvport" },
150 	{ Opt_fscache, "fsc" },
151 	{ Opt_nofscache, "nofsc" },
152 
153 	{ Opt_port, "port=%s" },
154 	{ Opt_rsize, "rsize=%s" },
155 	{ Opt_wsize, "wsize=%s" },
156 	{ Opt_bsize, "bsize=%s" },
157 	{ Opt_timeo, "timeo=%s" },
158 	{ Opt_retrans, "retrans=%s" },
159 	{ Opt_acregmin, "acregmin=%s" },
160 	{ Opt_acregmax, "acregmax=%s" },
161 	{ Opt_acdirmin, "acdirmin=%s" },
162 	{ Opt_acdirmax, "acdirmax=%s" },
163 	{ Opt_actimeo, "actimeo=%s" },
164 	{ Opt_namelen, "namlen=%s" },
165 	{ Opt_mountport, "mountport=%s" },
166 	{ Opt_mountvers, "mountvers=%s" },
167 	{ Opt_nfsvers, "nfsvers=%s" },
168 	{ Opt_nfsvers, "vers=%s" },
169 	{ Opt_minorversion, "minorversion=%s" },
170 
171 	{ Opt_sec, "sec=%s" },
172 	{ Opt_proto, "proto=%s" },
173 	{ Opt_mountproto, "mountproto=%s" },
174 	{ Opt_addr, "addr=%s" },
175 	{ Opt_clientaddr, "clientaddr=%s" },
176 	{ Opt_mounthost, "mounthost=%s" },
177 	{ Opt_mountaddr, "mountaddr=%s" },
178 
179 	{ Opt_lookupcache, "lookupcache=%s" },
180 	{ Opt_fscache_uniq, "fsc=%s" },
181 	{ Opt_local_lock, "local_lock=%s" },
182 
183 	{ Opt_err, NULL }
184 };
185 
186 enum {
187 	Opt_xprt_udp, Opt_xprt_udp6, Opt_xprt_tcp, Opt_xprt_tcp6, Opt_xprt_rdma,
188 
189 	Opt_xprt_err
190 };
191 
192 static const match_table_t nfs_xprt_protocol_tokens = {
193 	{ Opt_xprt_udp, "udp" },
194 	{ Opt_xprt_udp6, "udp6" },
195 	{ Opt_xprt_tcp, "tcp" },
196 	{ Opt_xprt_tcp6, "tcp6" },
197 	{ Opt_xprt_rdma, "rdma" },
198 
199 	{ Opt_xprt_err, NULL }
200 };
201 
202 enum {
203 	Opt_sec_none, Opt_sec_sys,
204 	Opt_sec_krb5, Opt_sec_krb5i, Opt_sec_krb5p,
205 	Opt_sec_lkey, Opt_sec_lkeyi, Opt_sec_lkeyp,
206 	Opt_sec_spkm, Opt_sec_spkmi, Opt_sec_spkmp,
207 
208 	Opt_sec_err
209 };
210 
211 static const match_table_t nfs_secflavor_tokens = {
212 	{ Opt_sec_none, "none" },
213 	{ Opt_sec_none, "null" },
214 	{ Opt_sec_sys, "sys" },
215 
216 	{ Opt_sec_krb5, "krb5" },
217 	{ Opt_sec_krb5i, "krb5i" },
218 	{ Opt_sec_krb5p, "krb5p" },
219 
220 	{ Opt_sec_lkey, "lkey" },
221 	{ Opt_sec_lkeyi, "lkeyi" },
222 	{ Opt_sec_lkeyp, "lkeyp" },
223 
224 	{ Opt_sec_spkm, "spkm3" },
225 	{ Opt_sec_spkmi, "spkm3i" },
226 	{ Opt_sec_spkmp, "spkm3p" },
227 
228 	{ Opt_sec_err, NULL }
229 };
230 
231 enum {
232 	Opt_lookupcache_all, Opt_lookupcache_positive,
233 	Opt_lookupcache_none,
234 
235 	Opt_lookupcache_err
236 };
237 
238 static match_table_t nfs_lookupcache_tokens = {
239 	{ Opt_lookupcache_all, "all" },
240 	{ Opt_lookupcache_positive, "pos" },
241 	{ Opt_lookupcache_positive, "positive" },
242 	{ Opt_lookupcache_none, "none" },
243 
244 	{ Opt_lookupcache_err, NULL }
245 };
246 
247 enum {
248 	Opt_local_lock_all, Opt_local_lock_flock, Opt_local_lock_posix,
249 	Opt_local_lock_none,
250 
251 	Opt_local_lock_err
252 };
253 
254 static match_table_t nfs_local_lock_tokens = {
255 	{ Opt_local_lock_all, "all" },
256 	{ Opt_local_lock_flock, "flock" },
257 	{ Opt_local_lock_posix, "posix" },
258 	{ Opt_local_lock_none, "none" },
259 
260 	{ Opt_local_lock_err, NULL }
261 };
262 
263 
264 static void nfs_umount_begin(struct super_block *);
265 static int  nfs_statfs(struct dentry *, struct kstatfs *);
266 static int  nfs_show_options(struct seq_file *, struct vfsmount *);
267 static int  nfs_show_devname(struct seq_file *, struct vfsmount *);
268 static int  nfs_show_path(struct seq_file *, struct vfsmount *);
269 static int  nfs_show_stats(struct seq_file *, struct vfsmount *);
270 static struct dentry *nfs_fs_mount(struct file_system_type *,
271 		int, const char *, void *);
272 static struct dentry *nfs_xdev_mount(struct file_system_type *fs_type,
273 		int flags, const char *dev_name, void *raw_data);
274 static void nfs_put_super(struct super_block *);
275 static void nfs_kill_super(struct super_block *);
276 static int nfs_remount(struct super_block *sb, int *flags, char *raw_data);
277 
278 static struct file_system_type nfs_fs_type = {
279 	.owner		= THIS_MODULE,
280 	.name		= "nfs",
281 	.mount		= nfs_fs_mount,
282 	.kill_sb	= nfs_kill_super,
283 	.fs_flags	= FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
284 };
285 
286 struct file_system_type nfs_xdev_fs_type = {
287 	.owner		= THIS_MODULE,
288 	.name		= "nfs",
289 	.mount		= nfs_xdev_mount,
290 	.kill_sb	= nfs_kill_super,
291 	.fs_flags	= FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
292 };
293 
294 static const struct super_operations nfs_sops = {
295 	.alloc_inode	= nfs_alloc_inode,
296 	.destroy_inode	= nfs_destroy_inode,
297 	.write_inode	= nfs_write_inode,
298 	.put_super	= nfs_put_super,
299 	.statfs		= nfs_statfs,
300 	.evict_inode	= nfs_evict_inode,
301 	.umount_begin	= nfs_umount_begin,
302 	.show_options	= nfs_show_options,
303 	.show_devname	= nfs_show_devname,
304 	.show_path	= nfs_show_path,
305 	.show_stats	= nfs_show_stats,
306 	.remount_fs	= nfs_remount,
307 };
308 
309 #ifdef CONFIG_NFS_V4
310 static int nfs4_validate_text_mount_data(void *options,
311 	struct nfs_parsed_mount_data *args, const char *dev_name);
312 static struct dentry *nfs4_try_mount(int flags, const char *dev_name,
313 	struct nfs_parsed_mount_data *data);
314 static struct dentry *nfs4_mount(struct file_system_type *fs_type,
315 	int flags, const char *dev_name, void *raw_data);
316 static struct dentry *nfs4_remote_mount(struct file_system_type *fs_type,
317 	int flags, const char *dev_name, void *raw_data);
318 static struct dentry *nfs4_xdev_mount(struct file_system_type *fs_type,
319 	int flags, const char *dev_name, void *raw_data);
320 static struct dentry *nfs4_referral_mount(struct file_system_type *fs_type,
321 	int flags, const char *dev_name, void *raw_data);
322 static struct dentry *nfs4_remote_referral_mount(struct file_system_type *fs_type,
323 	int flags, const char *dev_name, void *raw_data);
324 static void nfs4_kill_super(struct super_block *sb);
325 
326 static struct file_system_type nfs4_fs_type = {
327 	.owner		= THIS_MODULE,
328 	.name		= "nfs4",
329 	.mount		= nfs4_mount,
330 	.kill_sb	= nfs4_kill_super,
331 	.fs_flags	= FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
332 };
333 
334 static struct file_system_type nfs4_remote_fs_type = {
335 	.owner		= THIS_MODULE,
336 	.name		= "nfs4",
337 	.mount		= nfs4_remote_mount,
338 	.kill_sb	= nfs4_kill_super,
339 	.fs_flags	= FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
340 };
341 
342 struct file_system_type nfs4_xdev_fs_type = {
343 	.owner		= THIS_MODULE,
344 	.name		= "nfs4",
345 	.mount		= nfs4_xdev_mount,
346 	.kill_sb	= nfs4_kill_super,
347 	.fs_flags	= FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
348 };
349 
350 static struct file_system_type nfs4_remote_referral_fs_type = {
351 	.owner		= THIS_MODULE,
352 	.name		= "nfs4",
353 	.mount		= nfs4_remote_referral_mount,
354 	.kill_sb	= nfs4_kill_super,
355 	.fs_flags	= FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
356 };
357 
358 struct file_system_type nfs4_referral_fs_type = {
359 	.owner		= THIS_MODULE,
360 	.name		= "nfs4",
361 	.mount		= nfs4_referral_mount,
362 	.kill_sb	= nfs4_kill_super,
363 	.fs_flags	= FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
364 };
365 
366 static const struct super_operations nfs4_sops = {
367 	.alloc_inode	= nfs_alloc_inode,
368 	.destroy_inode	= nfs_destroy_inode,
369 	.write_inode	= nfs_write_inode,
370 	.put_super	= nfs_put_super,
371 	.statfs		= nfs_statfs,
372 	.evict_inode	= nfs4_evict_inode,
373 	.umount_begin	= nfs_umount_begin,
374 	.show_options	= nfs_show_options,
375 	.show_devname	= nfs_show_devname,
376 	.show_path	= nfs_show_path,
377 	.show_stats	= nfs_show_stats,
378 	.remount_fs	= nfs_remount,
379 };
380 #endif
381 
382 static struct shrinker acl_shrinker = {
383 	.shrink		= nfs_access_cache_shrinker,
384 	.seeks		= DEFAULT_SEEKS,
385 };
386 
387 /*
388  * Register the NFS filesystems
389  */
390 int __init register_nfs_fs(void)
391 {
392 	int ret;
393 
394         ret = register_filesystem(&nfs_fs_type);
395 	if (ret < 0)
396 		goto error_0;
397 
398 	ret = nfs_register_sysctl();
399 	if (ret < 0)
400 		goto error_1;
401 #ifdef CONFIG_NFS_V4
402 	ret = register_filesystem(&nfs4_fs_type);
403 	if (ret < 0)
404 		goto error_2;
405 #endif
406 	register_shrinker(&acl_shrinker);
407 	return 0;
408 
409 #ifdef CONFIG_NFS_V4
410 error_2:
411 	nfs_unregister_sysctl();
412 #endif
413 error_1:
414 	unregister_filesystem(&nfs_fs_type);
415 error_0:
416 	return ret;
417 }
418 
419 /*
420  * Unregister the NFS filesystems
421  */
422 void __exit unregister_nfs_fs(void)
423 {
424 	unregister_shrinker(&acl_shrinker);
425 #ifdef CONFIG_NFS_V4
426 	unregister_filesystem(&nfs4_fs_type);
427 #endif
428 	nfs_unregister_sysctl();
429 	unregister_filesystem(&nfs_fs_type);
430 }
431 
432 void nfs_sb_active(struct super_block *sb)
433 {
434 	struct nfs_server *server = NFS_SB(sb);
435 
436 	if (atomic_inc_return(&server->active) == 1)
437 		atomic_inc(&sb->s_active);
438 }
439 
440 void nfs_sb_deactive(struct super_block *sb)
441 {
442 	struct nfs_server *server = NFS_SB(sb);
443 
444 	if (atomic_dec_and_test(&server->active))
445 		deactivate_super(sb);
446 }
447 
448 /*
449  * Deliver file system statistics to userspace
450  */
451 static int nfs_statfs(struct dentry *dentry, struct kstatfs *buf)
452 {
453 	struct nfs_server *server = NFS_SB(dentry->d_sb);
454 	unsigned char blockbits;
455 	unsigned long blockres;
456 	struct nfs_fh *fh = NFS_FH(dentry->d_inode);
457 	struct nfs_fsstat res;
458 	int error = -ENOMEM;
459 
460 	res.fattr = nfs_alloc_fattr();
461 	if (res.fattr == NULL)
462 		goto out_err;
463 
464 	error = server->nfs_client->rpc_ops->statfs(server, fh, &res);
465 	if (unlikely(error == -ESTALE)) {
466 		struct dentry *pd_dentry;
467 
468 		pd_dentry = dget_parent(dentry);
469 		if (pd_dentry != NULL) {
470 			nfs_zap_caches(pd_dentry->d_inode);
471 			dput(pd_dentry);
472 		}
473 	}
474 	nfs_free_fattr(res.fattr);
475 	if (error < 0)
476 		goto out_err;
477 
478 	buf->f_type = NFS_SUPER_MAGIC;
479 
480 	/*
481 	 * Current versions of glibc do not correctly handle the
482 	 * case where f_frsize != f_bsize.  Eventually we want to
483 	 * report the value of wtmult in this field.
484 	 */
485 	buf->f_frsize = dentry->d_sb->s_blocksize;
486 
487 	/*
488 	 * On most *nix systems, f_blocks, f_bfree, and f_bavail
489 	 * are reported in units of f_frsize.  Linux hasn't had
490 	 * an f_frsize field in its statfs struct until recently,
491 	 * thus historically Linux's sys_statfs reports these
492 	 * fields in units of f_bsize.
493 	 */
494 	buf->f_bsize = dentry->d_sb->s_blocksize;
495 	blockbits = dentry->d_sb->s_blocksize_bits;
496 	blockres = (1 << blockbits) - 1;
497 	buf->f_blocks = (res.tbytes + blockres) >> blockbits;
498 	buf->f_bfree = (res.fbytes + blockres) >> blockbits;
499 	buf->f_bavail = (res.abytes + blockres) >> blockbits;
500 
501 	buf->f_files = res.tfiles;
502 	buf->f_ffree = res.afiles;
503 
504 	buf->f_namelen = server->namelen;
505 
506 	return 0;
507 
508  out_err:
509 	dprintk("%s: statfs error = %d\n", __func__, -error);
510 	return error;
511 }
512 
513 /*
514  * Map the security flavour number to a name
515  */
516 static const char *nfs_pseudoflavour_to_name(rpc_authflavor_t flavour)
517 {
518 	static const struct {
519 		rpc_authflavor_t flavour;
520 		const char *str;
521 	} sec_flavours[] = {
522 		{ RPC_AUTH_NULL, "null" },
523 		{ RPC_AUTH_UNIX, "sys" },
524 		{ RPC_AUTH_GSS_KRB5, "krb5" },
525 		{ RPC_AUTH_GSS_KRB5I, "krb5i" },
526 		{ RPC_AUTH_GSS_KRB5P, "krb5p" },
527 		{ RPC_AUTH_GSS_LKEY, "lkey" },
528 		{ RPC_AUTH_GSS_LKEYI, "lkeyi" },
529 		{ RPC_AUTH_GSS_LKEYP, "lkeyp" },
530 		{ RPC_AUTH_GSS_SPKM, "spkm" },
531 		{ RPC_AUTH_GSS_SPKMI, "spkmi" },
532 		{ RPC_AUTH_GSS_SPKMP, "spkmp" },
533 		{ UINT_MAX, "unknown" }
534 	};
535 	int i;
536 
537 	for (i = 0; sec_flavours[i].flavour != UINT_MAX; i++) {
538 		if (sec_flavours[i].flavour == flavour)
539 			break;
540 	}
541 	return sec_flavours[i].str;
542 }
543 
544 static void nfs_show_mountd_netid(struct seq_file *m, struct nfs_server *nfss,
545 				  int showdefaults)
546 {
547 	struct sockaddr *sap = (struct sockaddr *) &nfss->mountd_address;
548 
549 	seq_printf(m, ",mountproto=");
550 	switch (sap->sa_family) {
551 	case AF_INET:
552 		switch (nfss->mountd_protocol) {
553 		case IPPROTO_UDP:
554 			seq_printf(m, RPCBIND_NETID_UDP);
555 			break;
556 		case IPPROTO_TCP:
557 			seq_printf(m, RPCBIND_NETID_TCP);
558 			break;
559 		default:
560 			if (showdefaults)
561 				seq_printf(m, "auto");
562 		}
563 		break;
564 	case AF_INET6:
565 		switch (nfss->mountd_protocol) {
566 		case IPPROTO_UDP:
567 			seq_printf(m, RPCBIND_NETID_UDP6);
568 			break;
569 		case IPPROTO_TCP:
570 			seq_printf(m, RPCBIND_NETID_TCP6);
571 			break;
572 		default:
573 			if (showdefaults)
574 				seq_printf(m, "auto");
575 		}
576 		break;
577 	default:
578 		if (showdefaults)
579 			seq_printf(m, "auto");
580 	}
581 }
582 
583 static void nfs_show_mountd_options(struct seq_file *m, struct nfs_server *nfss,
584 				    int showdefaults)
585 {
586 	struct sockaddr *sap = (struct sockaddr *)&nfss->mountd_address;
587 
588 	if (nfss->flags & NFS_MOUNT_LEGACY_INTERFACE)
589 		return;
590 
591 	switch (sap->sa_family) {
592 	case AF_INET: {
593 		struct sockaddr_in *sin = (struct sockaddr_in *)sap;
594 		seq_printf(m, ",mountaddr=%pI4", &sin->sin_addr.s_addr);
595 		break;
596 	}
597 	case AF_INET6: {
598 		struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sap;
599 		seq_printf(m, ",mountaddr=%pI6c", &sin6->sin6_addr);
600 		break;
601 	}
602 	default:
603 		if (showdefaults)
604 			seq_printf(m, ",mountaddr=unspecified");
605 	}
606 
607 	if (nfss->mountd_version || showdefaults)
608 		seq_printf(m, ",mountvers=%u", nfss->mountd_version);
609 	if ((nfss->mountd_port &&
610 		nfss->mountd_port != (unsigned short)NFS_UNSPEC_PORT) ||
611 		showdefaults)
612 		seq_printf(m, ",mountport=%u", nfss->mountd_port);
613 
614 	nfs_show_mountd_netid(m, nfss, showdefaults);
615 }
616 
617 #ifdef CONFIG_NFS_V4
618 static void nfs_show_nfsv4_options(struct seq_file *m, struct nfs_server *nfss,
619 				    int showdefaults)
620 {
621 	struct nfs_client *clp = nfss->nfs_client;
622 
623 	seq_printf(m, ",clientaddr=%s", clp->cl_ipaddr);
624 	seq_printf(m, ",minorversion=%u", clp->cl_minorversion);
625 }
626 #else
627 static void nfs_show_nfsv4_options(struct seq_file *m, struct nfs_server *nfss,
628 				    int showdefaults)
629 {
630 }
631 #endif
632 
633 /*
634  * Describe the mount options in force on this server representation
635  */
636 static void nfs_show_mount_options(struct seq_file *m, struct nfs_server *nfss,
637 				   int showdefaults)
638 {
639 	static const struct proc_nfs_info {
640 		int flag;
641 		const char *str;
642 		const char *nostr;
643 	} nfs_info[] = {
644 		{ NFS_MOUNT_SOFT, ",soft", ",hard" },
645 		{ NFS_MOUNT_POSIX, ",posix", "" },
646 		{ NFS_MOUNT_NOCTO, ",nocto", "" },
647 		{ NFS_MOUNT_NOAC, ",noac", "" },
648 		{ NFS_MOUNT_NONLM, ",nolock", "" },
649 		{ NFS_MOUNT_NOACL, ",noacl", "" },
650 		{ NFS_MOUNT_NORDIRPLUS, ",nordirplus", "" },
651 		{ NFS_MOUNT_UNSHARED, ",nosharecache", "" },
652 		{ NFS_MOUNT_NORESVPORT, ",noresvport", "" },
653 		{ 0, NULL, NULL }
654 	};
655 	const struct proc_nfs_info *nfs_infop;
656 	struct nfs_client *clp = nfss->nfs_client;
657 	u32 version = clp->rpc_ops->version;
658 	int local_flock, local_fcntl;
659 
660 	seq_printf(m, ",vers=%u", version);
661 	seq_printf(m, ",rsize=%u", nfss->rsize);
662 	seq_printf(m, ",wsize=%u", nfss->wsize);
663 	if (nfss->bsize != 0)
664 		seq_printf(m, ",bsize=%u", nfss->bsize);
665 	seq_printf(m, ",namlen=%u", nfss->namelen);
666 	if (nfss->acregmin != NFS_DEF_ACREGMIN*HZ || showdefaults)
667 		seq_printf(m, ",acregmin=%u", nfss->acregmin/HZ);
668 	if (nfss->acregmax != NFS_DEF_ACREGMAX*HZ || showdefaults)
669 		seq_printf(m, ",acregmax=%u", nfss->acregmax/HZ);
670 	if (nfss->acdirmin != NFS_DEF_ACDIRMIN*HZ || showdefaults)
671 		seq_printf(m, ",acdirmin=%u", nfss->acdirmin/HZ);
672 	if (nfss->acdirmax != NFS_DEF_ACDIRMAX*HZ || showdefaults)
673 		seq_printf(m, ",acdirmax=%u", nfss->acdirmax/HZ);
674 	for (nfs_infop = nfs_info; nfs_infop->flag; nfs_infop++) {
675 		if (nfss->flags & nfs_infop->flag)
676 			seq_puts(m, nfs_infop->str);
677 		else
678 			seq_puts(m, nfs_infop->nostr);
679 	}
680 	seq_printf(m, ",proto=%s",
681 		   rpc_peeraddr2str(nfss->client, RPC_DISPLAY_NETID));
682 	if (version == 4) {
683 		if (nfss->port != NFS_PORT)
684 			seq_printf(m, ",port=%u", nfss->port);
685 	} else
686 		if (nfss->port)
687 			seq_printf(m, ",port=%u", nfss->port);
688 
689 	seq_printf(m, ",timeo=%lu", 10U * nfss->client->cl_timeout->to_initval / HZ);
690 	seq_printf(m, ",retrans=%u", nfss->client->cl_timeout->to_retries);
691 	seq_printf(m, ",sec=%s", nfs_pseudoflavour_to_name(nfss->client->cl_auth->au_flavor));
692 
693 	if (version != 4)
694 		nfs_show_mountd_options(m, nfss, showdefaults);
695 	else
696 		nfs_show_nfsv4_options(m, nfss, showdefaults);
697 
698 	if (nfss->options & NFS_OPTION_FSCACHE)
699 		seq_printf(m, ",fsc");
700 
701 	if (nfss->flags & NFS_MOUNT_LOOKUP_CACHE_NONEG) {
702 		if (nfss->flags & NFS_MOUNT_LOOKUP_CACHE_NONE)
703 			seq_printf(m, ",lookupcache=none");
704 		else
705 			seq_printf(m, ",lookupcache=pos");
706 	}
707 
708 	local_flock = nfss->flags & NFS_MOUNT_LOCAL_FLOCK;
709 	local_fcntl = nfss->flags & NFS_MOUNT_LOCAL_FCNTL;
710 
711 	if (!local_flock && !local_fcntl)
712 		seq_printf(m, ",local_lock=none");
713 	else if (local_flock && local_fcntl)
714 		seq_printf(m, ",local_lock=all");
715 	else if (local_flock)
716 		seq_printf(m, ",local_lock=flock");
717 	else
718 		seq_printf(m, ",local_lock=posix");
719 }
720 
721 /*
722  * Describe the mount options on this VFS mountpoint
723  */
724 static int nfs_show_options(struct seq_file *m, struct vfsmount *mnt)
725 {
726 	struct nfs_server *nfss = NFS_SB(mnt->mnt_sb);
727 
728 	nfs_show_mount_options(m, nfss, 0);
729 
730 	seq_printf(m, ",addr=%s",
731 			rpc_peeraddr2str(nfss->nfs_client->cl_rpcclient,
732 							RPC_DISPLAY_ADDR));
733 
734 	return 0;
735 }
736 
737 #ifdef CONFIG_NFS_V4
738 #ifdef CONFIG_NFS_V4_1
739 static void show_sessions(struct seq_file *m, struct nfs_server *server)
740 {
741 	if (nfs4_has_session(server->nfs_client))
742 		seq_printf(m, ",sessions");
743 }
744 #else
745 static void show_sessions(struct seq_file *m, struct nfs_server *server) {}
746 #endif
747 #endif
748 
749 #ifdef CONFIG_NFS_V4
750 #ifdef CONFIG_NFS_V4_1
751 static void show_pnfs(struct seq_file *m, struct nfs_server *server)
752 {
753 	seq_printf(m, ",pnfs=");
754 	if (server->pnfs_curr_ld)
755 		seq_printf(m, "%s", server->pnfs_curr_ld->name);
756 	else
757 		seq_printf(m, "not configured");
758 }
759 #else
760 static void show_pnfs(struct seq_file *m, struct nfs_server *server) {}
761 #endif
762 #endif
763 
764 static int nfs_show_devname(struct seq_file *m, struct vfsmount *mnt)
765 {
766 	char *page = (char *) __get_free_page(GFP_KERNEL);
767 	char *devname, *dummy;
768 	int err = 0;
769 	if (!page)
770 		return -ENOMEM;
771 	devname = nfs_path(&dummy, mnt->mnt_root, page, PAGE_SIZE);
772 	if (IS_ERR(devname))
773 		err = PTR_ERR(devname);
774 	else
775 		seq_escape(m, devname, " \t\n\\");
776 	free_page((unsigned long)page);
777 	return err;
778 }
779 
780 static int nfs_show_path(struct seq_file *m, struct vfsmount *mnt)
781 {
782 	seq_puts(m, "/");
783 	return 0;
784 }
785 
786 /*
787  * Present statistical information for this VFS mountpoint
788  */
789 static int nfs_show_stats(struct seq_file *m, struct vfsmount *mnt)
790 {
791 	int i, cpu;
792 	struct nfs_server *nfss = NFS_SB(mnt->mnt_sb);
793 	struct rpc_auth *auth = nfss->client->cl_auth;
794 	struct nfs_iostats totals = { };
795 
796 	seq_printf(m, "statvers=%s", NFS_IOSTAT_VERS);
797 
798 	/*
799 	 * Display all mount option settings
800 	 */
801 	seq_printf(m, "\n\topts:\t");
802 	seq_puts(m, mnt->mnt_sb->s_flags & MS_RDONLY ? "ro" : "rw");
803 	seq_puts(m, mnt->mnt_sb->s_flags & MS_SYNCHRONOUS ? ",sync" : "");
804 	seq_puts(m, mnt->mnt_sb->s_flags & MS_NOATIME ? ",noatime" : "");
805 	seq_puts(m, mnt->mnt_sb->s_flags & MS_NODIRATIME ? ",nodiratime" : "");
806 	nfs_show_mount_options(m, nfss, 1);
807 
808 	seq_printf(m, "\n\tage:\t%lu", (jiffies - nfss->mount_time) / HZ);
809 
810 	seq_printf(m, "\n\tcaps:\t");
811 	seq_printf(m, "caps=0x%x", nfss->caps);
812 	seq_printf(m, ",wtmult=%u", nfss->wtmult);
813 	seq_printf(m, ",dtsize=%u", nfss->dtsize);
814 	seq_printf(m, ",bsize=%u", nfss->bsize);
815 	seq_printf(m, ",namlen=%u", nfss->namelen);
816 
817 #ifdef CONFIG_NFS_V4
818 	if (nfss->nfs_client->rpc_ops->version == 4) {
819 		seq_printf(m, "\n\tnfsv4:\t");
820 		seq_printf(m, "bm0=0x%x", nfss->attr_bitmask[0]);
821 		seq_printf(m, ",bm1=0x%x", nfss->attr_bitmask[1]);
822 		seq_printf(m, ",acl=0x%x", nfss->acl_bitmask);
823 		show_sessions(m, nfss);
824 		show_pnfs(m, nfss);
825 	}
826 #endif
827 
828 	/*
829 	 * Display security flavor in effect for this mount
830 	 */
831 	seq_printf(m, "\n\tsec:\tflavor=%u", auth->au_ops->au_flavor);
832 	if (auth->au_flavor)
833 		seq_printf(m, ",pseudoflavor=%u", auth->au_flavor);
834 
835 	/*
836 	 * Display superblock I/O counters
837 	 */
838 	for_each_possible_cpu(cpu) {
839 		struct nfs_iostats *stats;
840 
841 		preempt_disable();
842 		stats = per_cpu_ptr(nfss->io_stats, cpu);
843 
844 		for (i = 0; i < __NFSIOS_COUNTSMAX; i++)
845 			totals.events[i] += stats->events[i];
846 		for (i = 0; i < __NFSIOS_BYTESMAX; i++)
847 			totals.bytes[i] += stats->bytes[i];
848 #ifdef CONFIG_NFS_FSCACHE
849 		for (i = 0; i < __NFSIOS_FSCACHEMAX; i++)
850 			totals.fscache[i] += stats->fscache[i];
851 #endif
852 
853 		preempt_enable();
854 	}
855 
856 	seq_printf(m, "\n\tevents:\t");
857 	for (i = 0; i < __NFSIOS_COUNTSMAX; i++)
858 		seq_printf(m, "%lu ", totals.events[i]);
859 	seq_printf(m, "\n\tbytes:\t");
860 	for (i = 0; i < __NFSIOS_BYTESMAX; i++)
861 		seq_printf(m, "%Lu ", totals.bytes[i]);
862 #ifdef CONFIG_NFS_FSCACHE
863 	if (nfss->options & NFS_OPTION_FSCACHE) {
864 		seq_printf(m, "\n\tfsc:\t");
865 		for (i = 0; i < __NFSIOS_FSCACHEMAX; i++)
866 			seq_printf(m, "%Lu ", totals.bytes[i]);
867 	}
868 #endif
869 	seq_printf(m, "\n");
870 
871 	rpc_print_iostats(m, nfss->client);
872 
873 	return 0;
874 }
875 
876 /*
877  * Begin unmount by attempting to remove all automounted mountpoints we added
878  * in response to xdev traversals and referrals
879  */
880 static void nfs_umount_begin(struct super_block *sb)
881 {
882 	struct nfs_server *server;
883 	struct rpc_clnt *rpc;
884 
885 	server = NFS_SB(sb);
886 	/* -EIO all pending I/O */
887 	rpc = server->client_acl;
888 	if (!IS_ERR(rpc))
889 		rpc_killall_tasks(rpc);
890 	rpc = server->client;
891 	if (!IS_ERR(rpc))
892 		rpc_killall_tasks(rpc);
893 }
894 
895 static struct nfs_parsed_mount_data *nfs_alloc_parsed_mount_data(unsigned int version)
896 {
897 	struct nfs_parsed_mount_data *data;
898 
899 	data = kzalloc(sizeof(*data), GFP_KERNEL);
900 	if (data) {
901 		data->acregmin		= NFS_DEF_ACREGMIN;
902 		data->acregmax		= NFS_DEF_ACREGMAX;
903 		data->acdirmin		= NFS_DEF_ACDIRMIN;
904 		data->acdirmax		= NFS_DEF_ACDIRMAX;
905 		data->mount_server.port	= NFS_UNSPEC_PORT;
906 		data->nfs_server.port	= NFS_UNSPEC_PORT;
907 		data->nfs_server.protocol = XPRT_TRANSPORT_TCP;
908 		data->auth_flavors[0]	= RPC_AUTH_UNIX;
909 		data->auth_flavor_len	= 1;
910 		data->version		= version;
911 		data->minorversion	= 0;
912 	}
913 	return data;
914 }
915 
916 /*
917  * Sanity-check a server address provided by the mount command.
918  *
919  * Address family must be initialized, and address must not be
920  * the ANY address for that family.
921  */
922 static int nfs_verify_server_address(struct sockaddr *addr)
923 {
924 	switch (addr->sa_family) {
925 	case AF_INET: {
926 		struct sockaddr_in *sa = (struct sockaddr_in *)addr;
927 		return sa->sin_addr.s_addr != htonl(INADDR_ANY);
928 	}
929 	case AF_INET6: {
930 		struct in6_addr *sa = &((struct sockaddr_in6 *)addr)->sin6_addr;
931 		return !ipv6_addr_any(sa);
932 	}
933 	}
934 
935 	dfprintk(MOUNT, "NFS: Invalid IP address specified\n");
936 	return 0;
937 }
938 
939 /*
940  * Select between a default port value and a user-specified port value.
941  * If a zero value is set, then autobind will be used.
942  */
943 static void nfs_set_port(struct sockaddr *sap, int *port,
944 				 const unsigned short default_port)
945 {
946 	if (*port == NFS_UNSPEC_PORT)
947 		*port = default_port;
948 
949 	rpc_set_port(sap, *port);
950 }
951 
952 /*
953  * Sanity check the NFS transport protocol.
954  *
955  */
956 static void nfs_validate_transport_protocol(struct nfs_parsed_mount_data *mnt)
957 {
958 	switch (mnt->nfs_server.protocol) {
959 	case XPRT_TRANSPORT_UDP:
960 	case XPRT_TRANSPORT_TCP:
961 	case XPRT_TRANSPORT_RDMA:
962 		break;
963 	default:
964 		mnt->nfs_server.protocol = XPRT_TRANSPORT_TCP;
965 	}
966 }
967 
968 /*
969  * For text based NFSv2/v3 mounts, the mount protocol transport default
970  * settings should depend upon the specified NFS transport.
971  */
972 static void nfs_set_mount_transport_protocol(struct nfs_parsed_mount_data *mnt)
973 {
974 	nfs_validate_transport_protocol(mnt);
975 
976 	if (mnt->mount_server.protocol == XPRT_TRANSPORT_UDP ||
977 	    mnt->mount_server.protocol == XPRT_TRANSPORT_TCP)
978 			return;
979 	switch (mnt->nfs_server.protocol) {
980 	case XPRT_TRANSPORT_UDP:
981 		mnt->mount_server.protocol = XPRT_TRANSPORT_UDP;
982 		break;
983 	case XPRT_TRANSPORT_TCP:
984 	case XPRT_TRANSPORT_RDMA:
985 		mnt->mount_server.protocol = XPRT_TRANSPORT_TCP;
986 	}
987 }
988 
989 /*
990  * Parse the value of the 'sec=' option.
991  */
992 static int nfs_parse_security_flavors(char *value,
993 				      struct nfs_parsed_mount_data *mnt)
994 {
995 	substring_t args[MAX_OPT_ARGS];
996 
997 	dfprintk(MOUNT, "NFS: parsing sec=%s option\n", value);
998 
999 	switch (match_token(value, nfs_secflavor_tokens, args)) {
1000 	case Opt_sec_none:
1001 		mnt->auth_flavors[0] = RPC_AUTH_NULL;
1002 		break;
1003 	case Opt_sec_sys:
1004 		mnt->auth_flavors[0] = RPC_AUTH_UNIX;
1005 		break;
1006 	case Opt_sec_krb5:
1007 		mnt->auth_flavors[0] = RPC_AUTH_GSS_KRB5;
1008 		break;
1009 	case Opt_sec_krb5i:
1010 		mnt->auth_flavors[0] = RPC_AUTH_GSS_KRB5I;
1011 		break;
1012 	case Opt_sec_krb5p:
1013 		mnt->auth_flavors[0] = RPC_AUTH_GSS_KRB5P;
1014 		break;
1015 	case Opt_sec_lkey:
1016 		mnt->auth_flavors[0] = RPC_AUTH_GSS_LKEY;
1017 		break;
1018 	case Opt_sec_lkeyi:
1019 		mnt->auth_flavors[0] = RPC_AUTH_GSS_LKEYI;
1020 		break;
1021 	case Opt_sec_lkeyp:
1022 		mnt->auth_flavors[0] = RPC_AUTH_GSS_LKEYP;
1023 		break;
1024 	case Opt_sec_spkm:
1025 		mnt->auth_flavors[0] = RPC_AUTH_GSS_SPKM;
1026 		break;
1027 	case Opt_sec_spkmi:
1028 		mnt->auth_flavors[0] = RPC_AUTH_GSS_SPKMI;
1029 		break;
1030 	case Opt_sec_spkmp:
1031 		mnt->auth_flavors[0] = RPC_AUTH_GSS_SPKMP;
1032 		break;
1033 	default:
1034 		return 0;
1035 	}
1036 
1037 	mnt->flags |= NFS_MOUNT_SECFLAVOUR;
1038 	mnt->auth_flavor_len = 1;
1039 	return 1;
1040 }
1041 
1042 static int nfs_get_option_str(substring_t args[], char **option)
1043 {
1044 	kfree(*option);
1045 	*option = match_strdup(args);
1046 	return !option;
1047 }
1048 
1049 static int nfs_get_option_ul(substring_t args[], unsigned long *option)
1050 {
1051 	int rc;
1052 	char *string;
1053 
1054 	string = match_strdup(args);
1055 	if (string == NULL)
1056 		return -ENOMEM;
1057 	rc = strict_strtoul(string, 10, option);
1058 	kfree(string);
1059 
1060 	return rc;
1061 }
1062 
1063 /*
1064  * Error-check and convert a string of mount options from user space into
1065  * a data structure.  The whole mount string is processed; bad options are
1066  * skipped as they are encountered.  If there were no errors, return 1;
1067  * otherwise return 0 (zero).
1068  */
1069 static int nfs_parse_mount_options(char *raw,
1070 				   struct nfs_parsed_mount_data *mnt)
1071 {
1072 	char *p, *string, *secdata;
1073 	int rc, sloppy = 0, invalid_option = 0;
1074 	unsigned short protofamily = AF_UNSPEC;
1075 	unsigned short mountfamily = AF_UNSPEC;
1076 
1077 	if (!raw) {
1078 		dfprintk(MOUNT, "NFS: mount options string was NULL.\n");
1079 		return 1;
1080 	}
1081 	dfprintk(MOUNT, "NFS: nfs mount opts='%s'\n", raw);
1082 
1083 	secdata = alloc_secdata();
1084 	if (!secdata)
1085 		goto out_nomem;
1086 
1087 	rc = security_sb_copy_data(raw, secdata);
1088 	if (rc)
1089 		goto out_security_failure;
1090 
1091 	rc = security_sb_parse_opts_str(secdata, &mnt->lsm_opts);
1092 	if (rc)
1093 		goto out_security_failure;
1094 
1095 	free_secdata(secdata);
1096 
1097 	while ((p = strsep(&raw, ",")) != NULL) {
1098 		substring_t args[MAX_OPT_ARGS];
1099 		unsigned long option;
1100 		int token;
1101 
1102 		if (!*p)
1103 			continue;
1104 
1105 		dfprintk(MOUNT, "NFS:   parsing nfs mount option '%s'\n", p);
1106 
1107 		token = match_token(p, nfs_mount_option_tokens, args);
1108 		switch (token) {
1109 
1110 		/*
1111 		 * boolean options:  foo/nofoo
1112 		 */
1113 		case Opt_soft:
1114 			mnt->flags |= NFS_MOUNT_SOFT;
1115 			break;
1116 		case Opt_hard:
1117 			mnt->flags &= ~NFS_MOUNT_SOFT;
1118 			break;
1119 		case Opt_posix:
1120 			mnt->flags |= NFS_MOUNT_POSIX;
1121 			break;
1122 		case Opt_noposix:
1123 			mnt->flags &= ~NFS_MOUNT_POSIX;
1124 			break;
1125 		case Opt_cto:
1126 			mnt->flags &= ~NFS_MOUNT_NOCTO;
1127 			break;
1128 		case Opt_nocto:
1129 			mnt->flags |= NFS_MOUNT_NOCTO;
1130 			break;
1131 		case Opt_ac:
1132 			mnt->flags &= ~NFS_MOUNT_NOAC;
1133 			break;
1134 		case Opt_noac:
1135 			mnt->flags |= NFS_MOUNT_NOAC;
1136 			break;
1137 		case Opt_lock:
1138 			mnt->flags &= ~NFS_MOUNT_NONLM;
1139 			mnt->flags &= ~(NFS_MOUNT_LOCAL_FLOCK |
1140 					NFS_MOUNT_LOCAL_FCNTL);
1141 			break;
1142 		case Opt_nolock:
1143 			mnt->flags |= NFS_MOUNT_NONLM;
1144 			mnt->flags |= (NFS_MOUNT_LOCAL_FLOCK |
1145 				       NFS_MOUNT_LOCAL_FCNTL);
1146 			break;
1147 		case Opt_v2:
1148 			mnt->flags &= ~NFS_MOUNT_VER3;
1149 			mnt->version = 2;
1150 			break;
1151 		case Opt_v3:
1152 			mnt->flags |= NFS_MOUNT_VER3;
1153 			mnt->version = 3;
1154 			break;
1155 		case Opt_v4:
1156 			mnt->flags &= ~NFS_MOUNT_VER3;
1157 			mnt->version = 4;
1158 			break;
1159 		case Opt_udp:
1160 			mnt->flags &= ~NFS_MOUNT_TCP;
1161 			mnt->nfs_server.protocol = XPRT_TRANSPORT_UDP;
1162 			break;
1163 		case Opt_tcp:
1164 			mnt->flags |= NFS_MOUNT_TCP;
1165 			mnt->nfs_server.protocol = XPRT_TRANSPORT_TCP;
1166 			break;
1167 		case Opt_rdma:
1168 			mnt->flags |= NFS_MOUNT_TCP; /* for side protocols */
1169 			mnt->nfs_server.protocol = XPRT_TRANSPORT_RDMA;
1170 			xprt_load_transport(p);
1171 			break;
1172 		case Opt_acl:
1173 			mnt->flags &= ~NFS_MOUNT_NOACL;
1174 			break;
1175 		case Opt_noacl:
1176 			mnt->flags |= NFS_MOUNT_NOACL;
1177 			break;
1178 		case Opt_rdirplus:
1179 			mnt->flags &= ~NFS_MOUNT_NORDIRPLUS;
1180 			break;
1181 		case Opt_nordirplus:
1182 			mnt->flags |= NFS_MOUNT_NORDIRPLUS;
1183 			break;
1184 		case Opt_sharecache:
1185 			mnt->flags &= ~NFS_MOUNT_UNSHARED;
1186 			break;
1187 		case Opt_nosharecache:
1188 			mnt->flags |= NFS_MOUNT_UNSHARED;
1189 			break;
1190 		case Opt_resvport:
1191 			mnt->flags &= ~NFS_MOUNT_NORESVPORT;
1192 			break;
1193 		case Opt_noresvport:
1194 			mnt->flags |= NFS_MOUNT_NORESVPORT;
1195 			break;
1196 		case Opt_fscache:
1197 			mnt->options |= NFS_OPTION_FSCACHE;
1198 			kfree(mnt->fscache_uniq);
1199 			mnt->fscache_uniq = NULL;
1200 			break;
1201 		case Opt_nofscache:
1202 			mnt->options &= ~NFS_OPTION_FSCACHE;
1203 			kfree(mnt->fscache_uniq);
1204 			mnt->fscache_uniq = NULL;
1205 			break;
1206 
1207 		/*
1208 		 * options that take numeric values
1209 		 */
1210 		case Opt_port:
1211 			if (nfs_get_option_ul(args, &option) ||
1212 			    option > USHRT_MAX)
1213 				goto out_invalid_value;
1214 			mnt->nfs_server.port = option;
1215 			break;
1216 		case Opt_rsize:
1217 			if (nfs_get_option_ul(args, &option))
1218 				goto out_invalid_value;
1219 			mnt->rsize = option;
1220 			break;
1221 		case Opt_wsize:
1222 			if (nfs_get_option_ul(args, &option))
1223 				goto out_invalid_value;
1224 			mnt->wsize = option;
1225 			break;
1226 		case Opt_bsize:
1227 			if (nfs_get_option_ul(args, &option))
1228 				goto out_invalid_value;
1229 			mnt->bsize = option;
1230 			break;
1231 		case Opt_timeo:
1232 			if (nfs_get_option_ul(args, &option) || option == 0)
1233 				goto out_invalid_value;
1234 			mnt->timeo = option;
1235 			break;
1236 		case Opt_retrans:
1237 			if (nfs_get_option_ul(args, &option) || option == 0)
1238 				goto out_invalid_value;
1239 			mnt->retrans = option;
1240 			break;
1241 		case Opt_acregmin:
1242 			if (nfs_get_option_ul(args, &option))
1243 				goto out_invalid_value;
1244 			mnt->acregmin = option;
1245 			break;
1246 		case Opt_acregmax:
1247 			if (nfs_get_option_ul(args, &option))
1248 				goto out_invalid_value;
1249 			mnt->acregmax = option;
1250 			break;
1251 		case Opt_acdirmin:
1252 			if (nfs_get_option_ul(args, &option))
1253 				goto out_invalid_value;
1254 			mnt->acdirmin = option;
1255 			break;
1256 		case Opt_acdirmax:
1257 			if (nfs_get_option_ul(args, &option))
1258 				goto out_invalid_value;
1259 			mnt->acdirmax = option;
1260 			break;
1261 		case Opt_actimeo:
1262 			if (nfs_get_option_ul(args, &option))
1263 				goto out_invalid_value;
1264 			mnt->acregmin = mnt->acregmax =
1265 			mnt->acdirmin = mnt->acdirmax = option;
1266 			break;
1267 		case Opt_namelen:
1268 			if (nfs_get_option_ul(args, &option))
1269 				goto out_invalid_value;
1270 			mnt->namlen = option;
1271 			break;
1272 		case Opt_mountport:
1273 			if (nfs_get_option_ul(args, &option) ||
1274 			    option > USHRT_MAX)
1275 				goto out_invalid_value;
1276 			mnt->mount_server.port = option;
1277 			break;
1278 		case Opt_mountvers:
1279 			if (nfs_get_option_ul(args, &option) ||
1280 			    option < NFS_MNT_VERSION ||
1281 			    option > NFS_MNT3_VERSION)
1282 				goto out_invalid_value;
1283 			mnt->mount_server.version = option;
1284 			break;
1285 		case Opt_nfsvers:
1286 			if (nfs_get_option_ul(args, &option))
1287 				goto out_invalid_value;
1288 			switch (option) {
1289 			case NFS2_VERSION:
1290 				mnt->flags &= ~NFS_MOUNT_VER3;
1291 				mnt->version = 2;
1292 				break;
1293 			case NFS3_VERSION:
1294 				mnt->flags |= NFS_MOUNT_VER3;
1295 				mnt->version = 3;
1296 				break;
1297 			case NFS4_VERSION:
1298 				mnt->flags &= ~NFS_MOUNT_VER3;
1299 				mnt->version = 4;
1300 				break;
1301 			default:
1302 				goto out_invalid_value;
1303 			}
1304 			break;
1305 		case Opt_minorversion:
1306 			if (nfs_get_option_ul(args, &option))
1307 				goto out_invalid_value;
1308 			if (option > NFS4_MAX_MINOR_VERSION)
1309 				goto out_invalid_value;
1310 			mnt->minorversion = option;
1311 			break;
1312 
1313 		/*
1314 		 * options that take text values
1315 		 */
1316 		case Opt_sec:
1317 			string = match_strdup(args);
1318 			if (string == NULL)
1319 				goto out_nomem;
1320 			rc = nfs_parse_security_flavors(string, mnt);
1321 			kfree(string);
1322 			if (!rc) {
1323 				dfprintk(MOUNT, "NFS:   unrecognized "
1324 						"security flavor\n");
1325 				return 0;
1326 			}
1327 			break;
1328 		case Opt_proto:
1329 			string = match_strdup(args);
1330 			if (string == NULL)
1331 				goto out_nomem;
1332 			token = match_token(string,
1333 					    nfs_xprt_protocol_tokens, args);
1334 
1335 			protofamily = AF_INET;
1336 			switch (token) {
1337 			case Opt_xprt_udp6:
1338 				protofamily = AF_INET6;
1339 			case Opt_xprt_udp:
1340 				mnt->flags &= ~NFS_MOUNT_TCP;
1341 				mnt->nfs_server.protocol = XPRT_TRANSPORT_UDP;
1342 				break;
1343 			case Opt_xprt_tcp6:
1344 				protofamily = AF_INET6;
1345 			case Opt_xprt_tcp:
1346 				mnt->flags |= NFS_MOUNT_TCP;
1347 				mnt->nfs_server.protocol = XPRT_TRANSPORT_TCP;
1348 				break;
1349 			case Opt_xprt_rdma:
1350 				/* vector side protocols to TCP */
1351 				mnt->flags |= NFS_MOUNT_TCP;
1352 				mnt->nfs_server.protocol = XPRT_TRANSPORT_RDMA;
1353 				xprt_load_transport(string);
1354 				break;
1355 			default:
1356 				dfprintk(MOUNT, "NFS:   unrecognized "
1357 						"transport protocol\n");
1358 				kfree(string);
1359 				return 0;
1360 			}
1361 			kfree(string);
1362 			break;
1363 		case Opt_mountproto:
1364 			string = match_strdup(args);
1365 			if (string == NULL)
1366 				goto out_nomem;
1367 			token = match_token(string,
1368 					    nfs_xprt_protocol_tokens, args);
1369 			kfree(string);
1370 
1371 			mountfamily = AF_INET;
1372 			switch (token) {
1373 			case Opt_xprt_udp6:
1374 				mountfamily = AF_INET6;
1375 			case Opt_xprt_udp:
1376 				mnt->mount_server.protocol = XPRT_TRANSPORT_UDP;
1377 				break;
1378 			case Opt_xprt_tcp6:
1379 				mountfamily = AF_INET6;
1380 			case Opt_xprt_tcp:
1381 				mnt->mount_server.protocol = XPRT_TRANSPORT_TCP;
1382 				break;
1383 			case Opt_xprt_rdma: /* not used for side protocols */
1384 			default:
1385 				dfprintk(MOUNT, "NFS:   unrecognized "
1386 						"transport protocol\n");
1387 				return 0;
1388 			}
1389 			break;
1390 		case Opt_addr:
1391 			string = match_strdup(args);
1392 			if (string == NULL)
1393 				goto out_nomem;
1394 			mnt->nfs_server.addrlen =
1395 				rpc_pton(string, strlen(string),
1396 					(struct sockaddr *)
1397 					&mnt->nfs_server.address,
1398 					sizeof(mnt->nfs_server.address));
1399 			kfree(string);
1400 			if (mnt->nfs_server.addrlen == 0)
1401 				goto out_invalid_address;
1402 			break;
1403 		case Opt_clientaddr:
1404 			if (nfs_get_option_str(args, &mnt->client_address))
1405 				goto out_nomem;
1406 			break;
1407 		case Opt_mounthost:
1408 			if (nfs_get_option_str(args,
1409 					       &mnt->mount_server.hostname))
1410 				goto out_nomem;
1411 			break;
1412 		case Opt_mountaddr:
1413 			string = match_strdup(args);
1414 			if (string == NULL)
1415 				goto out_nomem;
1416 			mnt->mount_server.addrlen =
1417 				rpc_pton(string, strlen(string),
1418 					(struct sockaddr *)
1419 					&mnt->mount_server.address,
1420 					sizeof(mnt->mount_server.address));
1421 			kfree(string);
1422 			if (mnt->mount_server.addrlen == 0)
1423 				goto out_invalid_address;
1424 			break;
1425 		case Opt_lookupcache:
1426 			string = match_strdup(args);
1427 			if (string == NULL)
1428 				goto out_nomem;
1429 			token = match_token(string,
1430 					nfs_lookupcache_tokens, args);
1431 			kfree(string);
1432 			switch (token) {
1433 				case Opt_lookupcache_all:
1434 					mnt->flags &= ~(NFS_MOUNT_LOOKUP_CACHE_NONEG|NFS_MOUNT_LOOKUP_CACHE_NONE);
1435 					break;
1436 				case Opt_lookupcache_positive:
1437 					mnt->flags &= ~NFS_MOUNT_LOOKUP_CACHE_NONE;
1438 					mnt->flags |= NFS_MOUNT_LOOKUP_CACHE_NONEG;
1439 					break;
1440 				case Opt_lookupcache_none:
1441 					mnt->flags |= NFS_MOUNT_LOOKUP_CACHE_NONEG|NFS_MOUNT_LOOKUP_CACHE_NONE;
1442 					break;
1443 				default:
1444 					dfprintk(MOUNT, "NFS:   invalid "
1445 							"lookupcache argument\n");
1446 					return 0;
1447 			};
1448 			break;
1449 		case Opt_fscache_uniq:
1450 			if (nfs_get_option_str(args, &mnt->fscache_uniq))
1451 				goto out_nomem;
1452 			mnt->options |= NFS_OPTION_FSCACHE;
1453 			break;
1454 		case Opt_local_lock:
1455 			string = match_strdup(args);
1456 			if (string == NULL)
1457 				goto out_nomem;
1458 			token = match_token(string, nfs_local_lock_tokens,
1459 					args);
1460 			kfree(string);
1461 			switch (token) {
1462 			case Opt_local_lock_all:
1463 				mnt->flags |= (NFS_MOUNT_LOCAL_FLOCK |
1464 					       NFS_MOUNT_LOCAL_FCNTL);
1465 				break;
1466 			case Opt_local_lock_flock:
1467 				mnt->flags |= NFS_MOUNT_LOCAL_FLOCK;
1468 				break;
1469 			case Opt_local_lock_posix:
1470 				mnt->flags |= NFS_MOUNT_LOCAL_FCNTL;
1471 				break;
1472 			case Opt_local_lock_none:
1473 				mnt->flags &= ~(NFS_MOUNT_LOCAL_FLOCK |
1474 						NFS_MOUNT_LOCAL_FCNTL);
1475 				break;
1476 			default:
1477 				dfprintk(MOUNT, "NFS:	invalid	"
1478 						"local_lock argument\n");
1479 				return 0;
1480 			};
1481 			break;
1482 
1483 		/*
1484 		 * Special options
1485 		 */
1486 		case Opt_sloppy:
1487 			sloppy = 1;
1488 			dfprintk(MOUNT, "NFS:   relaxing parsing rules\n");
1489 			break;
1490 		case Opt_userspace:
1491 		case Opt_deprecated:
1492 			dfprintk(MOUNT, "NFS:   ignoring mount option "
1493 					"'%s'\n", p);
1494 			break;
1495 
1496 		default:
1497 			invalid_option = 1;
1498 			dfprintk(MOUNT, "NFS:   unrecognized mount option "
1499 					"'%s'\n", p);
1500 		}
1501 	}
1502 
1503 	if (!sloppy && invalid_option)
1504 		return 0;
1505 
1506 	/*
1507 	 * verify that any proto=/mountproto= options match the address
1508 	 * familiies in the addr=/mountaddr= options.
1509 	 */
1510 	if (protofamily != AF_UNSPEC &&
1511 	    protofamily != mnt->nfs_server.address.ss_family)
1512 		goto out_proto_mismatch;
1513 
1514 	if (mountfamily != AF_UNSPEC) {
1515 		if (mnt->mount_server.addrlen) {
1516 			if (mountfamily != mnt->mount_server.address.ss_family)
1517 				goto out_mountproto_mismatch;
1518 		} else {
1519 			if (mountfamily != mnt->nfs_server.address.ss_family)
1520 				goto out_mountproto_mismatch;
1521 		}
1522 	}
1523 
1524 	return 1;
1525 
1526 out_mountproto_mismatch:
1527 	printk(KERN_INFO "NFS: mount server address does not match mountproto= "
1528 			 "option\n");
1529 	return 0;
1530 out_proto_mismatch:
1531 	printk(KERN_INFO "NFS: server address does not match proto= option\n");
1532 	return 0;
1533 out_invalid_address:
1534 	printk(KERN_INFO "NFS: bad IP address specified: %s\n", p);
1535 	return 0;
1536 out_invalid_value:
1537 	printk(KERN_INFO "NFS: bad mount option value specified: %s\n", p);
1538 	return 0;
1539 out_nomem:
1540 	printk(KERN_INFO "NFS: not enough memory to parse option\n");
1541 	return 0;
1542 out_security_failure:
1543 	free_secdata(secdata);
1544 	printk(KERN_INFO "NFS: security options invalid: %d\n", rc);
1545 	return 0;
1546 }
1547 
1548 /*
1549  * Match the requested auth flavors with the list returned by
1550  * the server.  Returns zero and sets the mount's authentication
1551  * flavor on success; returns -EACCES if server does not support
1552  * the requested flavor.
1553  */
1554 static int nfs_walk_authlist(struct nfs_parsed_mount_data *args,
1555 			     struct nfs_mount_request *request)
1556 {
1557 	unsigned int i, j, server_authlist_len = *(request->auth_flav_len);
1558 
1559 	/*
1560 	 * Certain releases of Linux's mountd return an empty
1561 	 * flavor list.  To prevent behavioral regression with
1562 	 * these servers (ie. rejecting mounts that used to
1563 	 * succeed), revert to pre-2.6.32 behavior (no checking)
1564 	 * if the returned flavor list is empty.
1565 	 */
1566 	if (server_authlist_len == 0)
1567 		return 0;
1568 
1569 	/*
1570 	 * We avoid sophisticated negotiating here, as there are
1571 	 * plenty of cases where we can get it wrong, providing
1572 	 * either too little or too much security.
1573 	 *
1574 	 * RFC 2623, section 2.7 suggests we SHOULD prefer the
1575 	 * flavor listed first.  However, some servers list
1576 	 * AUTH_NULL first.  Our caller plants AUTH_SYS, the
1577 	 * preferred default, in args->auth_flavors[0] if user
1578 	 * didn't specify sec= mount option.
1579 	 */
1580 	for (i = 0; i < args->auth_flavor_len; i++)
1581 		for (j = 0; j < server_authlist_len; j++)
1582 			if (args->auth_flavors[i] == request->auth_flavs[j]) {
1583 				dfprintk(MOUNT, "NFS: using auth flavor %d\n",
1584 					request->auth_flavs[j]);
1585 				args->auth_flavors[0] = request->auth_flavs[j];
1586 				return 0;
1587 			}
1588 
1589 	dfprintk(MOUNT, "NFS: server does not support requested auth flavor\n");
1590 	nfs_umount(request);
1591 	return -EACCES;
1592 }
1593 
1594 /*
1595  * Use the remote server's MOUNT service to request the NFS file handle
1596  * corresponding to the provided path.
1597  */
1598 static int nfs_try_mount(struct nfs_parsed_mount_data *args,
1599 			 struct nfs_fh *root_fh)
1600 {
1601 	rpc_authflavor_t server_authlist[NFS_MAX_SECFLAVORS];
1602 	unsigned int server_authlist_len = ARRAY_SIZE(server_authlist);
1603 	struct nfs_mount_request request = {
1604 		.sap		= (struct sockaddr *)
1605 						&args->mount_server.address,
1606 		.dirpath	= args->nfs_server.export_path,
1607 		.protocol	= args->mount_server.protocol,
1608 		.fh		= root_fh,
1609 		.noresvport	= args->flags & NFS_MOUNT_NORESVPORT,
1610 		.auth_flav_len	= &server_authlist_len,
1611 		.auth_flavs	= server_authlist,
1612 	};
1613 	int status;
1614 
1615 	if (args->mount_server.version == 0) {
1616 		switch (args->version) {
1617 			default:
1618 				args->mount_server.version = NFS_MNT3_VERSION;
1619 				break;
1620 			case 2:
1621 				args->mount_server.version = NFS_MNT_VERSION;
1622 		}
1623 	}
1624 	request.version = args->mount_server.version;
1625 
1626 	if (args->mount_server.hostname)
1627 		request.hostname = args->mount_server.hostname;
1628 	else
1629 		request.hostname = args->nfs_server.hostname;
1630 
1631 	/*
1632 	 * Construct the mount server's address.
1633 	 */
1634 	if (args->mount_server.address.ss_family == AF_UNSPEC) {
1635 		memcpy(request.sap, &args->nfs_server.address,
1636 		       args->nfs_server.addrlen);
1637 		args->mount_server.addrlen = args->nfs_server.addrlen;
1638 	}
1639 	request.salen = args->mount_server.addrlen;
1640 	nfs_set_port(request.sap, &args->mount_server.port, 0);
1641 
1642 	/*
1643 	 * Now ask the mount server to map our export path
1644 	 * to a file handle.
1645 	 */
1646 	status = nfs_mount(&request);
1647 	if (status != 0) {
1648 		dfprintk(MOUNT, "NFS: unable to mount server %s, error %d\n",
1649 				request.hostname, status);
1650 		return status;
1651 	}
1652 
1653 	/*
1654 	 * MNTv1 (NFSv2) does not support auth flavor negotiation.
1655 	 */
1656 	if (args->mount_server.version != NFS_MNT3_VERSION)
1657 		return 0;
1658 	return nfs_walk_authlist(args, &request);
1659 }
1660 
1661 /*
1662  * Split "dev_name" into "hostname:export_path".
1663  *
1664  * The leftmost colon demarks the split between the server's hostname
1665  * and the export path.  If the hostname starts with a left square
1666  * bracket, then it may contain colons.
1667  *
1668  * Note: caller frees hostname and export path, even on error.
1669  */
1670 static int nfs_parse_devname(const char *dev_name,
1671 			     char **hostname, size_t maxnamlen,
1672 			     char **export_path, size_t maxpathlen)
1673 {
1674 	size_t len;
1675 	char *end;
1676 
1677 	/* Is the host name protected with square brakcets? */
1678 	if (*dev_name == '[') {
1679 		end = strchr(++dev_name, ']');
1680 		if (end == NULL || end[1] != ':')
1681 			goto out_bad_devname;
1682 
1683 		len = end - dev_name;
1684 		end++;
1685 	} else {
1686 		char *comma;
1687 
1688 		end = strchr(dev_name, ':');
1689 		if (end == NULL)
1690 			goto out_bad_devname;
1691 		len = end - dev_name;
1692 
1693 		/* kill possible hostname list: not supported */
1694 		comma = strchr(dev_name, ',');
1695 		if (comma != NULL && comma < end)
1696 			*comma = 0;
1697 	}
1698 
1699 	if (len > maxnamlen)
1700 		goto out_hostname;
1701 
1702 	/* N.B. caller will free nfs_server.hostname in all cases */
1703 	*hostname = kstrndup(dev_name, len, GFP_KERNEL);
1704 	if (*hostname == NULL)
1705 		goto out_nomem;
1706 	len = strlen(++end);
1707 	if (len > maxpathlen)
1708 		goto out_path;
1709 	*export_path = kstrndup(end, len, GFP_KERNEL);
1710 	if (!*export_path)
1711 		goto out_nomem;
1712 
1713 	dfprintk(MOUNT, "NFS: MNTPATH: '%s'\n", *export_path);
1714 	return 0;
1715 
1716 out_bad_devname:
1717 	dfprintk(MOUNT, "NFS: device name not in host:path format\n");
1718 	return -EINVAL;
1719 
1720 out_nomem:
1721 	dfprintk(MOUNT, "NFS: not enough memory to parse device name\n");
1722 	return -ENOMEM;
1723 
1724 out_hostname:
1725 	dfprintk(MOUNT, "NFS: server hostname too long\n");
1726 	return -ENAMETOOLONG;
1727 
1728 out_path:
1729 	dfprintk(MOUNT, "NFS: export pathname too long\n");
1730 	return -ENAMETOOLONG;
1731 }
1732 
1733 /*
1734  * Validate the NFS2/NFS3 mount data
1735  * - fills in the mount root filehandle
1736  *
1737  * For option strings, user space handles the following behaviors:
1738  *
1739  * + DNS: mapping server host name to IP address ("addr=" option)
1740  *
1741  * + failure mode: how to behave if a mount request can't be handled
1742  *   immediately ("fg/bg" option)
1743  *
1744  * + retry: how often to retry a mount request ("retry=" option)
1745  *
1746  * + breaking back: trying proto=udp after proto=tcp, v2 after v3,
1747  *   mountproto=tcp after mountproto=udp, and so on
1748  */
1749 static int nfs_validate_mount_data(void *options,
1750 				   struct nfs_parsed_mount_data *args,
1751 				   struct nfs_fh *mntfh,
1752 				   const char *dev_name)
1753 {
1754 	struct nfs_mount_data *data = (struct nfs_mount_data *)options;
1755 	struct sockaddr *sap = (struct sockaddr *)&args->nfs_server.address;
1756 
1757 	if (data == NULL)
1758 		goto out_no_data;
1759 
1760 	switch (data->version) {
1761 	case 1:
1762 		data->namlen = 0;
1763 	case 2:
1764 		data->bsize = 0;
1765 	case 3:
1766 		if (data->flags & NFS_MOUNT_VER3)
1767 			goto out_no_v3;
1768 		data->root.size = NFS2_FHSIZE;
1769 		memcpy(data->root.data, data->old_root.data, NFS2_FHSIZE);
1770 	case 4:
1771 		if (data->flags & NFS_MOUNT_SECFLAVOUR)
1772 			goto out_no_sec;
1773 	case 5:
1774 		memset(data->context, 0, sizeof(data->context));
1775 	case 6:
1776 		if (data->flags & NFS_MOUNT_VER3) {
1777 			if (data->root.size > NFS3_FHSIZE || data->root.size == 0)
1778 				goto out_invalid_fh;
1779 			mntfh->size = data->root.size;
1780 			args->version = 3;
1781 		} else {
1782 			mntfh->size = NFS2_FHSIZE;
1783 			args->version = 2;
1784 		}
1785 
1786 
1787 		memcpy(mntfh->data, data->root.data, mntfh->size);
1788 		if (mntfh->size < sizeof(mntfh->data))
1789 			memset(mntfh->data + mntfh->size, 0,
1790 			       sizeof(mntfh->data) - mntfh->size);
1791 
1792 		/*
1793 		 * Translate to nfs_parsed_mount_data, which nfs_fill_super
1794 		 * can deal with.
1795 		 */
1796 		args->flags		= data->flags & NFS_MOUNT_FLAGMASK;
1797 		args->flags		|= NFS_MOUNT_LEGACY_INTERFACE;
1798 		args->rsize		= data->rsize;
1799 		args->wsize		= data->wsize;
1800 		args->timeo		= data->timeo;
1801 		args->retrans		= data->retrans;
1802 		args->acregmin		= data->acregmin;
1803 		args->acregmax		= data->acregmax;
1804 		args->acdirmin		= data->acdirmin;
1805 		args->acdirmax		= data->acdirmax;
1806 
1807 		memcpy(sap, &data->addr, sizeof(data->addr));
1808 		args->nfs_server.addrlen = sizeof(data->addr);
1809 		if (!nfs_verify_server_address(sap))
1810 			goto out_no_address;
1811 
1812 		if (!(data->flags & NFS_MOUNT_TCP))
1813 			args->nfs_server.protocol = XPRT_TRANSPORT_UDP;
1814 		/* N.B. caller will free nfs_server.hostname in all cases */
1815 		args->nfs_server.hostname = kstrdup(data->hostname, GFP_KERNEL);
1816 		args->namlen		= data->namlen;
1817 		args->bsize		= data->bsize;
1818 
1819 		if (data->flags & NFS_MOUNT_SECFLAVOUR)
1820 			args->auth_flavors[0] = data->pseudoflavor;
1821 		if (!args->nfs_server.hostname)
1822 			goto out_nomem;
1823 
1824 		if (!(data->flags & NFS_MOUNT_NONLM))
1825 			args->flags &= ~(NFS_MOUNT_LOCAL_FLOCK|
1826 					 NFS_MOUNT_LOCAL_FCNTL);
1827 		else
1828 			args->flags |= (NFS_MOUNT_LOCAL_FLOCK|
1829 					NFS_MOUNT_LOCAL_FCNTL);
1830 		/*
1831 		 * The legacy version 6 binary mount data from userspace has a
1832 		 * field used only to transport selinux information into the
1833 		 * the kernel.  To continue to support that functionality we
1834 		 * have a touch of selinux knowledge here in the NFS code. The
1835 		 * userspace code converted context=blah to just blah so we are
1836 		 * converting back to the full string selinux understands.
1837 		 */
1838 		if (data->context[0]){
1839 #ifdef CONFIG_SECURITY_SELINUX
1840 			int rc;
1841 			char *opts_str = kmalloc(sizeof(data->context) + 8, GFP_KERNEL);
1842 			if (!opts_str)
1843 				return -ENOMEM;
1844 			strcpy(opts_str, "context=");
1845 			data->context[NFS_MAX_CONTEXT_LEN] = '\0';
1846 			strcat(opts_str, &data->context[0]);
1847 			rc = security_sb_parse_opts_str(opts_str, &args->lsm_opts);
1848 			kfree(opts_str);
1849 			if (rc)
1850 				return rc;
1851 #else
1852 			return -EINVAL;
1853 #endif
1854 		}
1855 
1856 		break;
1857 	default: {
1858 		int status;
1859 
1860 		if (nfs_parse_mount_options((char *)options, args) == 0)
1861 			return -EINVAL;
1862 
1863 		if (!nfs_verify_server_address(sap))
1864 			goto out_no_address;
1865 
1866 		if (args->version == 4)
1867 #ifdef CONFIG_NFS_V4
1868 			return nfs4_validate_text_mount_data(options,
1869 							     args, dev_name);
1870 #else
1871 			goto out_v4_not_compiled;
1872 #endif
1873 
1874 		nfs_set_port(sap, &args->nfs_server.port, 0);
1875 
1876 		nfs_set_mount_transport_protocol(args);
1877 
1878 		status = nfs_parse_devname(dev_name,
1879 					   &args->nfs_server.hostname,
1880 					   PAGE_SIZE,
1881 					   &args->nfs_server.export_path,
1882 					   NFS_MAXPATHLEN);
1883 		if (!status)
1884 			status = nfs_try_mount(args, mntfh);
1885 
1886 		kfree(args->nfs_server.export_path);
1887 		args->nfs_server.export_path = NULL;
1888 
1889 		if (status)
1890 			return status;
1891 
1892 		break;
1893 		}
1894 	}
1895 
1896 #ifndef CONFIG_NFS_V3
1897 	if (args->version == 3)
1898 		goto out_v3_not_compiled;
1899 #endif /* !CONFIG_NFS_V3 */
1900 
1901 	return 0;
1902 
1903 out_no_data:
1904 	dfprintk(MOUNT, "NFS: mount program didn't pass any mount data\n");
1905 	return -EINVAL;
1906 
1907 out_no_v3:
1908 	dfprintk(MOUNT, "NFS: nfs_mount_data version %d does not support v3\n",
1909 		 data->version);
1910 	return -EINVAL;
1911 
1912 out_no_sec:
1913 	dfprintk(MOUNT, "NFS: nfs_mount_data version supports only AUTH_SYS\n");
1914 	return -EINVAL;
1915 
1916 #ifndef CONFIG_NFS_V3
1917 out_v3_not_compiled:
1918 	dfprintk(MOUNT, "NFS: NFSv3 is not compiled into kernel\n");
1919 	return -EPROTONOSUPPORT;
1920 #endif /* !CONFIG_NFS_V3 */
1921 
1922 #ifndef CONFIG_NFS_V4
1923 out_v4_not_compiled:
1924 	dfprintk(MOUNT, "NFS: NFSv4 is not compiled into kernel\n");
1925 	return -EPROTONOSUPPORT;
1926 #endif /* !CONFIG_NFS_V4 */
1927 
1928 out_nomem:
1929 	dfprintk(MOUNT, "NFS: not enough memory to handle mount options\n");
1930 	return -ENOMEM;
1931 
1932 out_no_address:
1933 	dfprintk(MOUNT, "NFS: mount program didn't pass remote address\n");
1934 	return -EINVAL;
1935 
1936 out_invalid_fh:
1937 	dfprintk(MOUNT, "NFS: invalid root filehandle\n");
1938 	return -EINVAL;
1939 }
1940 
1941 static int
1942 nfs_compare_remount_data(struct nfs_server *nfss,
1943 			 struct nfs_parsed_mount_data *data)
1944 {
1945 	if (data->flags != nfss->flags ||
1946 	    data->rsize != nfss->rsize ||
1947 	    data->wsize != nfss->wsize ||
1948 	    data->retrans != nfss->client->cl_timeout->to_retries ||
1949 	    data->auth_flavors[0] != nfss->client->cl_auth->au_flavor ||
1950 	    data->acregmin != nfss->acregmin / HZ ||
1951 	    data->acregmax != nfss->acregmax / HZ ||
1952 	    data->acdirmin != nfss->acdirmin / HZ ||
1953 	    data->acdirmax != nfss->acdirmax / HZ ||
1954 	    data->timeo != (10U * nfss->client->cl_timeout->to_initval / HZ) ||
1955 	    data->nfs_server.port != nfss->port ||
1956 	    data->nfs_server.addrlen != nfss->nfs_client->cl_addrlen ||
1957 	    !rpc_cmp_addr((struct sockaddr *)&data->nfs_server.address,
1958 			  (struct sockaddr *)&nfss->nfs_client->cl_addr))
1959 		return -EINVAL;
1960 
1961 	return 0;
1962 }
1963 
1964 static int
1965 nfs_remount(struct super_block *sb, int *flags, char *raw_data)
1966 {
1967 	int error;
1968 	struct nfs_server *nfss = sb->s_fs_info;
1969 	struct nfs_parsed_mount_data *data;
1970 	struct nfs_mount_data *options = (struct nfs_mount_data *)raw_data;
1971 	struct nfs4_mount_data *options4 = (struct nfs4_mount_data *)raw_data;
1972 	u32 nfsvers = nfss->nfs_client->rpc_ops->version;
1973 
1974 	/*
1975 	 * Userspace mount programs that send binary options generally send
1976 	 * them populated with default values. We have no way to know which
1977 	 * ones were explicitly specified. Fall back to legacy behavior and
1978 	 * just return success.
1979 	 */
1980 	if ((nfsvers == 4 && (!options4 || options4->version == 1)) ||
1981 	    (nfsvers <= 3 && (!options || (options->version >= 1 &&
1982 					   options->version <= 6))))
1983 		return 0;
1984 
1985 	data = kzalloc(sizeof(*data), GFP_KERNEL);
1986 	if (data == NULL)
1987 		return -ENOMEM;
1988 
1989 	/* fill out struct with values from existing mount */
1990 	data->flags = nfss->flags;
1991 	data->rsize = nfss->rsize;
1992 	data->wsize = nfss->wsize;
1993 	data->retrans = nfss->client->cl_timeout->to_retries;
1994 	data->auth_flavors[0] = nfss->client->cl_auth->au_flavor;
1995 	data->acregmin = nfss->acregmin / HZ;
1996 	data->acregmax = nfss->acregmax / HZ;
1997 	data->acdirmin = nfss->acdirmin / HZ;
1998 	data->acdirmax = nfss->acdirmax / HZ;
1999 	data->timeo = 10U * nfss->client->cl_timeout->to_initval / HZ;
2000 	data->nfs_server.port = nfss->port;
2001 	data->nfs_server.addrlen = nfss->nfs_client->cl_addrlen;
2002 	memcpy(&data->nfs_server.address, &nfss->nfs_client->cl_addr,
2003 		data->nfs_server.addrlen);
2004 
2005 	/* overwrite those values with any that were specified */
2006 	error = nfs_parse_mount_options((char *)options, data);
2007 	if (error < 0)
2008 		goto out;
2009 
2010 	/*
2011 	 * noac is a special case. It implies -o sync, but that's not
2012 	 * necessarily reflected in the mtab options. do_remount_sb
2013 	 * will clear MS_SYNCHRONOUS if -o sync wasn't specified in the
2014 	 * remount options, so we have to explicitly reset it.
2015 	 */
2016 	if (data->flags & NFS_MOUNT_NOAC)
2017 		*flags |= MS_SYNCHRONOUS;
2018 
2019 	/* compare new mount options with old ones */
2020 	error = nfs_compare_remount_data(nfss, data);
2021 out:
2022 	kfree(data);
2023 	return error;
2024 }
2025 
2026 /*
2027  * Initialise the common bits of the superblock
2028  */
2029 static inline void nfs_initialise_sb(struct super_block *sb)
2030 {
2031 	struct nfs_server *server = NFS_SB(sb);
2032 
2033 	sb->s_magic = NFS_SUPER_MAGIC;
2034 
2035 	/* We probably want something more informative here */
2036 	snprintf(sb->s_id, sizeof(sb->s_id),
2037 		 "%x:%x", MAJOR(sb->s_dev), MINOR(sb->s_dev));
2038 
2039 	if (sb->s_blocksize == 0)
2040 		sb->s_blocksize = nfs_block_bits(server->wsize,
2041 						 &sb->s_blocksize_bits);
2042 
2043 	sb->s_bdi = &server->backing_dev_info;
2044 
2045 	nfs_super_set_maxbytes(sb, server->maxfilesize);
2046 }
2047 
2048 /*
2049  * Finish setting up an NFS2/3 superblock
2050  */
2051 static void nfs_fill_super(struct super_block *sb,
2052 			   struct nfs_parsed_mount_data *data)
2053 {
2054 	struct nfs_server *server = NFS_SB(sb);
2055 
2056 	sb->s_blocksize_bits = 0;
2057 	sb->s_blocksize = 0;
2058 	if (data->bsize)
2059 		sb->s_blocksize = nfs_block_size(data->bsize, &sb->s_blocksize_bits);
2060 
2061 	if (server->nfs_client->rpc_ops->version == 3) {
2062 		/* The VFS shouldn't apply the umask to mode bits. We will do
2063 		 * so ourselves when necessary.
2064 		 */
2065 		sb->s_flags |= MS_POSIXACL;
2066 		sb->s_time_gran = 1;
2067 	}
2068 
2069 	sb->s_op = &nfs_sops;
2070  	nfs_initialise_sb(sb);
2071 }
2072 
2073 /*
2074  * Finish setting up a cloned NFS2/3 superblock
2075  */
2076 static void nfs_clone_super(struct super_block *sb,
2077 			    const struct super_block *old_sb)
2078 {
2079 	struct nfs_server *server = NFS_SB(sb);
2080 
2081 	sb->s_blocksize_bits = old_sb->s_blocksize_bits;
2082 	sb->s_blocksize = old_sb->s_blocksize;
2083 	sb->s_maxbytes = old_sb->s_maxbytes;
2084 
2085 	if (server->nfs_client->rpc_ops->version == 3) {
2086 		/* The VFS shouldn't apply the umask to mode bits. We will do
2087 		 * so ourselves when necessary.
2088 		 */
2089 		sb->s_flags |= MS_POSIXACL;
2090 		sb->s_time_gran = 1;
2091 	}
2092 
2093 	sb->s_op = old_sb->s_op;
2094  	nfs_initialise_sb(sb);
2095 }
2096 
2097 static int nfs_compare_mount_options(const struct super_block *s, const struct nfs_server *b, int flags)
2098 {
2099 	const struct nfs_server *a = s->s_fs_info;
2100 	const struct rpc_clnt *clnt_a = a->client;
2101 	const struct rpc_clnt *clnt_b = b->client;
2102 
2103 	if ((s->s_flags & NFS_MS_MASK) != (flags & NFS_MS_MASK))
2104 		goto Ebusy;
2105 	if (a->nfs_client != b->nfs_client)
2106 		goto Ebusy;
2107 	if (a->flags != b->flags)
2108 		goto Ebusy;
2109 	if (a->wsize != b->wsize)
2110 		goto Ebusy;
2111 	if (a->rsize != b->rsize)
2112 		goto Ebusy;
2113 	if (a->acregmin != b->acregmin)
2114 		goto Ebusy;
2115 	if (a->acregmax != b->acregmax)
2116 		goto Ebusy;
2117 	if (a->acdirmin != b->acdirmin)
2118 		goto Ebusy;
2119 	if (a->acdirmax != b->acdirmax)
2120 		goto Ebusy;
2121 	if (clnt_a->cl_auth->au_flavor != clnt_b->cl_auth->au_flavor)
2122 		goto Ebusy;
2123 	return 1;
2124 Ebusy:
2125 	return 0;
2126 }
2127 
2128 struct nfs_sb_mountdata {
2129 	struct nfs_server *server;
2130 	int mntflags;
2131 };
2132 
2133 static int nfs_set_super(struct super_block *s, void *data)
2134 {
2135 	struct nfs_sb_mountdata *sb_mntdata = data;
2136 	struct nfs_server *server = sb_mntdata->server;
2137 	int ret;
2138 
2139 	s->s_flags = sb_mntdata->mntflags;
2140 	s->s_fs_info = server;
2141 	s->s_d_op = server->nfs_client->rpc_ops->dentry_ops;
2142 	ret = set_anon_super(s, server);
2143 	if (ret == 0)
2144 		server->s_dev = s->s_dev;
2145 	return ret;
2146 }
2147 
2148 static int nfs_compare_super_address(struct nfs_server *server1,
2149 				     struct nfs_server *server2)
2150 {
2151 	struct sockaddr *sap1, *sap2;
2152 
2153 	sap1 = (struct sockaddr *)&server1->nfs_client->cl_addr;
2154 	sap2 = (struct sockaddr *)&server2->nfs_client->cl_addr;
2155 
2156 	if (sap1->sa_family != sap2->sa_family)
2157 		return 0;
2158 
2159 	switch (sap1->sa_family) {
2160 	case AF_INET: {
2161 		struct sockaddr_in *sin1 = (struct sockaddr_in *)sap1;
2162 		struct sockaddr_in *sin2 = (struct sockaddr_in *)sap2;
2163 		if (sin1->sin_addr.s_addr != sin2->sin_addr.s_addr)
2164 			return 0;
2165 		if (sin1->sin_port != sin2->sin_port)
2166 			return 0;
2167 		break;
2168 	}
2169 	case AF_INET6: {
2170 		struct sockaddr_in6 *sin1 = (struct sockaddr_in6 *)sap1;
2171 		struct sockaddr_in6 *sin2 = (struct sockaddr_in6 *)sap2;
2172 		if (!ipv6_addr_equal(&sin1->sin6_addr, &sin2->sin6_addr))
2173 			return 0;
2174 		if (sin1->sin6_port != sin2->sin6_port)
2175 			return 0;
2176 		break;
2177 	}
2178 	default:
2179 		return 0;
2180 	}
2181 
2182 	return 1;
2183 }
2184 
2185 static int nfs_compare_super(struct super_block *sb, void *data)
2186 {
2187 	struct nfs_sb_mountdata *sb_mntdata = data;
2188 	struct nfs_server *server = sb_mntdata->server, *old = NFS_SB(sb);
2189 	int mntflags = sb_mntdata->mntflags;
2190 
2191 	if (!nfs_compare_super_address(old, server))
2192 		return 0;
2193 	/* Note: NFS_MOUNT_UNSHARED == NFS4_MOUNT_UNSHARED */
2194 	if (old->flags & NFS_MOUNT_UNSHARED)
2195 		return 0;
2196 	if (memcmp(&old->fsid, &server->fsid, sizeof(old->fsid)) != 0)
2197 		return 0;
2198 	return nfs_compare_mount_options(sb, server, mntflags);
2199 }
2200 
2201 static int nfs_bdi_register(struct nfs_server *server)
2202 {
2203 	return bdi_register_dev(&server->backing_dev_info, server->s_dev);
2204 }
2205 
2206 static struct dentry *nfs_fs_mount(struct file_system_type *fs_type,
2207 	int flags, const char *dev_name, void *raw_data)
2208 {
2209 	struct nfs_server *server = NULL;
2210 	struct super_block *s;
2211 	struct nfs_parsed_mount_data *data;
2212 	struct nfs_fh *mntfh;
2213 	struct dentry *mntroot = ERR_PTR(-ENOMEM);
2214 	int (*compare_super)(struct super_block *, void *) = nfs_compare_super;
2215 	struct nfs_sb_mountdata sb_mntdata = {
2216 		.mntflags = flags,
2217 	};
2218 	int error;
2219 
2220 	data = nfs_alloc_parsed_mount_data(NFS_DEFAULT_VERSION);
2221 	mntfh = nfs_alloc_fhandle();
2222 	if (data == NULL || mntfh == NULL)
2223 		goto out_free_fh;
2224 
2225 	security_init_mnt_opts(&data->lsm_opts);
2226 
2227 	/* Validate the mount data */
2228 	error = nfs_validate_mount_data(raw_data, data, mntfh, dev_name);
2229 	if (error < 0) {
2230 		mntroot = ERR_PTR(error);
2231 		goto out;
2232 	}
2233 
2234 #ifdef CONFIG_NFS_V4
2235 	if (data->version == 4) {
2236 		mntroot = nfs4_try_mount(flags, dev_name, data);
2237 		kfree(data->client_address);
2238 		kfree(data->nfs_server.export_path);
2239 		goto out;
2240 	}
2241 #endif	/* CONFIG_NFS_V4 */
2242 
2243 	/* Get a volume representation */
2244 	server = nfs_create_server(data, mntfh);
2245 	if (IS_ERR(server)) {
2246 		mntroot = ERR_CAST(server);
2247 		goto out;
2248 	}
2249 	sb_mntdata.server = server;
2250 
2251 	if (server->flags & NFS_MOUNT_UNSHARED)
2252 		compare_super = NULL;
2253 
2254 	/* -o noac implies -o sync */
2255 	if (server->flags & NFS_MOUNT_NOAC)
2256 		sb_mntdata.mntflags |= MS_SYNCHRONOUS;
2257 
2258 	/* Get a superblock - note that we may end up sharing one that already exists */
2259 	s = sget(fs_type, compare_super, nfs_set_super, &sb_mntdata);
2260 	if (IS_ERR(s)) {
2261 		mntroot = ERR_CAST(s);
2262 		goto out_err_nosb;
2263 	}
2264 
2265 	if (s->s_fs_info != server) {
2266 		nfs_free_server(server);
2267 		server = NULL;
2268 	} else {
2269 		error = nfs_bdi_register(server);
2270 		if (error) {
2271 			mntroot = ERR_PTR(error);
2272 			goto error_splat_bdi;
2273 		}
2274 	}
2275 
2276 	if (!s->s_root) {
2277 		/* initial superblock/root creation */
2278 		nfs_fill_super(s, data);
2279 		nfs_fscache_get_super_cookie(s, data->fscache_uniq, NULL);
2280 	}
2281 
2282 	mntroot = nfs_get_root(s, mntfh, dev_name);
2283 	if (IS_ERR(mntroot))
2284 		goto error_splat_super;
2285 
2286 	error = security_sb_set_mnt_opts(s, &data->lsm_opts);
2287 	if (error)
2288 		goto error_splat_root;
2289 
2290 	s->s_flags |= MS_ACTIVE;
2291 
2292 out:
2293 	kfree(data->nfs_server.hostname);
2294 	kfree(data->mount_server.hostname);
2295 	kfree(data->fscache_uniq);
2296 	security_free_mnt_opts(&data->lsm_opts);
2297 out_free_fh:
2298 	nfs_free_fhandle(mntfh);
2299 	kfree(data);
2300 	return mntroot;
2301 
2302 out_err_nosb:
2303 	nfs_free_server(server);
2304 	goto out;
2305 
2306 error_splat_root:
2307 	dput(mntroot);
2308 	mntroot = ERR_PTR(error);
2309 error_splat_super:
2310 	if (server && !s->s_root)
2311 		bdi_unregister(&server->backing_dev_info);
2312 error_splat_bdi:
2313 	deactivate_locked_super(s);
2314 	goto out;
2315 }
2316 
2317 /*
2318  * Ensure that we unregister the bdi before kill_anon_super
2319  * releases the device name
2320  */
2321 static void nfs_put_super(struct super_block *s)
2322 {
2323 	struct nfs_server *server = NFS_SB(s);
2324 
2325 	bdi_unregister(&server->backing_dev_info);
2326 }
2327 
2328 /*
2329  * Destroy an NFS2/3 superblock
2330  */
2331 static void nfs_kill_super(struct super_block *s)
2332 {
2333 	struct nfs_server *server = NFS_SB(s);
2334 
2335 	kill_anon_super(s);
2336 	nfs_fscache_release_super_cookie(s);
2337 	nfs_free_server(server);
2338 }
2339 
2340 /*
2341  * Clone an NFS2/3 server record on xdev traversal (FSID-change)
2342  */
2343 static struct dentry *
2344 nfs_xdev_mount(struct file_system_type *fs_type, int flags,
2345 		const char *dev_name, void *raw_data)
2346 {
2347 	struct nfs_clone_mount *data = raw_data;
2348 	struct super_block *s;
2349 	struct nfs_server *server;
2350 	struct dentry *mntroot;
2351 	int (*compare_super)(struct super_block *, void *) = nfs_compare_super;
2352 	struct nfs_sb_mountdata sb_mntdata = {
2353 		.mntflags = flags,
2354 	};
2355 	int error;
2356 
2357 	dprintk("--> nfs_xdev_mount()\n");
2358 
2359 	/* create a new volume representation */
2360 	server = nfs_clone_server(NFS_SB(data->sb), data->fh, data->fattr);
2361 	if (IS_ERR(server)) {
2362 		error = PTR_ERR(server);
2363 		goto out_err_noserver;
2364 	}
2365 	sb_mntdata.server = server;
2366 
2367 	if (server->flags & NFS_MOUNT_UNSHARED)
2368 		compare_super = NULL;
2369 
2370 	/* -o noac implies -o sync */
2371 	if (server->flags & NFS_MOUNT_NOAC)
2372 		sb_mntdata.mntflags |= MS_SYNCHRONOUS;
2373 
2374 	/* Get a superblock - note that we may end up sharing one that already exists */
2375 	s = sget(&nfs_fs_type, compare_super, nfs_set_super, &sb_mntdata);
2376 	if (IS_ERR(s)) {
2377 		error = PTR_ERR(s);
2378 		goto out_err_nosb;
2379 	}
2380 
2381 	if (s->s_fs_info != server) {
2382 		nfs_free_server(server);
2383 		server = NULL;
2384 	} else {
2385 		error = nfs_bdi_register(server);
2386 		if (error)
2387 			goto error_splat_bdi;
2388 	}
2389 
2390 	if (!s->s_root) {
2391 		/* initial superblock/root creation */
2392 		nfs_clone_super(s, data->sb);
2393 		nfs_fscache_get_super_cookie(s, NULL, data);
2394 	}
2395 
2396 	mntroot = nfs_get_root(s, data->fh, dev_name);
2397 	if (IS_ERR(mntroot)) {
2398 		error = PTR_ERR(mntroot);
2399 		goto error_splat_super;
2400 	}
2401 	if (mntroot->d_inode->i_op != NFS_SB(s)->nfs_client->rpc_ops->dir_inode_ops) {
2402 		dput(mntroot);
2403 		error = -ESTALE;
2404 		goto error_splat_super;
2405 	}
2406 
2407 	s->s_flags |= MS_ACTIVE;
2408 
2409 	/* clone any lsm security options from the parent to the new sb */
2410 	security_sb_clone_mnt_opts(data->sb, s);
2411 
2412 	dprintk("<-- nfs_xdev_mount() = 0\n");
2413 	return mntroot;
2414 
2415 out_err_nosb:
2416 	nfs_free_server(server);
2417 out_err_noserver:
2418 	dprintk("<-- nfs_xdev_mount() = %d [error]\n", error);
2419 	return ERR_PTR(error);
2420 
2421 error_splat_super:
2422 	if (server && !s->s_root)
2423 		bdi_unregister(&server->backing_dev_info);
2424 error_splat_bdi:
2425 	deactivate_locked_super(s);
2426 	dprintk("<-- nfs_xdev_mount() = %d [splat]\n", error);
2427 	return ERR_PTR(error);
2428 }
2429 
2430 #ifdef CONFIG_NFS_V4
2431 
2432 /*
2433  * Finish setting up a cloned NFS4 superblock
2434  */
2435 static void nfs4_clone_super(struct super_block *sb,
2436 			    const struct super_block *old_sb)
2437 {
2438 	sb->s_blocksize_bits = old_sb->s_blocksize_bits;
2439 	sb->s_blocksize = old_sb->s_blocksize;
2440 	sb->s_maxbytes = old_sb->s_maxbytes;
2441 	sb->s_time_gran = 1;
2442 	sb->s_op = old_sb->s_op;
2443 	/*
2444 	 * The VFS shouldn't apply the umask to mode bits. We will do
2445 	 * so ourselves when necessary.
2446 	 */
2447 	sb->s_flags  |= MS_POSIXACL;
2448 	sb->s_xattr  = old_sb->s_xattr;
2449 	nfs_initialise_sb(sb);
2450 }
2451 
2452 /*
2453  * Set up an NFS4 superblock
2454  */
2455 static void nfs4_fill_super(struct super_block *sb)
2456 {
2457 	sb->s_time_gran = 1;
2458 	sb->s_op = &nfs4_sops;
2459 	/*
2460 	 * The VFS shouldn't apply the umask to mode bits. We will do
2461 	 * so ourselves when necessary.
2462 	 */
2463 	sb->s_flags  |= MS_POSIXACL;
2464 	sb->s_xattr = nfs4_xattr_handlers;
2465 	nfs_initialise_sb(sb);
2466 }
2467 
2468 static void nfs4_validate_mount_flags(struct nfs_parsed_mount_data *args)
2469 {
2470 	args->flags &= ~(NFS_MOUNT_NONLM|NFS_MOUNT_NOACL|NFS_MOUNT_VER3|
2471 			 NFS_MOUNT_LOCAL_FLOCK|NFS_MOUNT_LOCAL_FCNTL);
2472 }
2473 
2474 static int nfs4_validate_text_mount_data(void *options,
2475 					 struct nfs_parsed_mount_data *args,
2476 					 const char *dev_name)
2477 {
2478 	struct sockaddr *sap = (struct sockaddr *)&args->nfs_server.address;
2479 
2480 	nfs_set_port(sap, &args->nfs_server.port, NFS_PORT);
2481 
2482 	nfs_validate_transport_protocol(args);
2483 
2484 	nfs4_validate_mount_flags(args);
2485 
2486 	if (args->version != 4) {
2487 		dfprintk(MOUNT,
2488 			 "NFS4: Illegal mount version\n");
2489 		return -EINVAL;
2490 	}
2491 
2492 	if (args->auth_flavor_len > 1) {
2493 		dfprintk(MOUNT,
2494 			 "NFS4: Too many RPC auth flavours specified\n");
2495 		return -EINVAL;
2496 	}
2497 
2498 	if (args->client_address == NULL) {
2499 		dfprintk(MOUNT,
2500 			 "NFS4: mount program didn't pass callback address\n");
2501 		return -EINVAL;
2502 	}
2503 
2504 	return nfs_parse_devname(dev_name,
2505 				   &args->nfs_server.hostname,
2506 				   NFS4_MAXNAMLEN,
2507 				   &args->nfs_server.export_path,
2508 				   NFS4_MAXPATHLEN);
2509 }
2510 
2511 /*
2512  * Validate NFSv4 mount options
2513  */
2514 static int nfs4_validate_mount_data(void *options,
2515 				    struct nfs_parsed_mount_data *args,
2516 				    const char *dev_name)
2517 {
2518 	struct sockaddr *sap = (struct sockaddr *)&args->nfs_server.address;
2519 	struct nfs4_mount_data *data = (struct nfs4_mount_data *)options;
2520 	char *c;
2521 
2522 	if (data == NULL)
2523 		goto out_no_data;
2524 
2525 	switch (data->version) {
2526 	case 1:
2527 		if (data->host_addrlen > sizeof(args->nfs_server.address))
2528 			goto out_no_address;
2529 		if (data->host_addrlen == 0)
2530 			goto out_no_address;
2531 		args->nfs_server.addrlen = data->host_addrlen;
2532 		if (copy_from_user(sap, data->host_addr, data->host_addrlen))
2533 			return -EFAULT;
2534 		if (!nfs_verify_server_address(sap))
2535 			goto out_no_address;
2536 
2537 		if (data->auth_flavourlen) {
2538 			if (data->auth_flavourlen > 1)
2539 				goto out_inval_auth;
2540 			if (copy_from_user(&args->auth_flavors[0],
2541 					   data->auth_flavours,
2542 					   sizeof(args->auth_flavors[0])))
2543 				return -EFAULT;
2544 		}
2545 
2546 		c = strndup_user(data->hostname.data, NFS4_MAXNAMLEN);
2547 		if (IS_ERR(c))
2548 			return PTR_ERR(c);
2549 		args->nfs_server.hostname = c;
2550 
2551 		c = strndup_user(data->mnt_path.data, NFS4_MAXPATHLEN);
2552 		if (IS_ERR(c))
2553 			return PTR_ERR(c);
2554 		args->nfs_server.export_path = c;
2555 		dfprintk(MOUNT, "NFS: MNTPATH: '%s'\n", c);
2556 
2557 		c = strndup_user(data->client_addr.data, 16);
2558 		if (IS_ERR(c))
2559 			return PTR_ERR(c);
2560 		args->client_address = c;
2561 
2562 		/*
2563 		 * Translate to nfs_parsed_mount_data, which nfs4_fill_super
2564 		 * can deal with.
2565 		 */
2566 
2567 		args->flags	= data->flags & NFS4_MOUNT_FLAGMASK;
2568 		args->rsize	= data->rsize;
2569 		args->wsize	= data->wsize;
2570 		args->timeo	= data->timeo;
2571 		args->retrans	= data->retrans;
2572 		args->acregmin	= data->acregmin;
2573 		args->acregmax	= data->acregmax;
2574 		args->acdirmin	= data->acdirmin;
2575 		args->acdirmax	= data->acdirmax;
2576 		args->nfs_server.protocol = data->proto;
2577 		nfs_validate_transport_protocol(args);
2578 
2579 		break;
2580 	default:
2581 		if (nfs_parse_mount_options((char *)options, args) == 0)
2582 			return -EINVAL;
2583 
2584 		if (!nfs_verify_server_address(sap))
2585 			return -EINVAL;
2586 
2587 		return nfs4_validate_text_mount_data(options, args, dev_name);
2588 	}
2589 
2590 	return 0;
2591 
2592 out_no_data:
2593 	dfprintk(MOUNT, "NFS4: mount program didn't pass any mount data\n");
2594 	return -EINVAL;
2595 
2596 out_inval_auth:
2597 	dfprintk(MOUNT, "NFS4: Invalid number of RPC auth flavours %d\n",
2598 		 data->auth_flavourlen);
2599 	return -EINVAL;
2600 
2601 out_no_address:
2602 	dfprintk(MOUNT, "NFS4: mount program didn't pass remote address\n");
2603 	return -EINVAL;
2604 }
2605 
2606 /*
2607  * Get the superblock for the NFS4 root partition
2608  */
2609 static struct dentry *
2610 nfs4_remote_mount(struct file_system_type *fs_type, int flags,
2611 		  const char *dev_name, void *raw_data)
2612 {
2613 	struct nfs_parsed_mount_data *data = raw_data;
2614 	struct super_block *s;
2615 	struct nfs_server *server;
2616 	struct nfs_fh *mntfh;
2617 	struct dentry *mntroot;
2618 	int (*compare_super)(struct super_block *, void *) = nfs_compare_super;
2619 	struct nfs_sb_mountdata sb_mntdata = {
2620 		.mntflags = flags,
2621 	};
2622 	int error = -ENOMEM;
2623 
2624 	mntfh = nfs_alloc_fhandle();
2625 	if (data == NULL || mntfh == NULL)
2626 		goto out_free_fh;
2627 
2628 	security_init_mnt_opts(&data->lsm_opts);
2629 
2630 	/* Get a volume representation */
2631 	server = nfs4_create_server(data, mntfh);
2632 	if (IS_ERR(server)) {
2633 		error = PTR_ERR(server);
2634 		goto out;
2635 	}
2636 	sb_mntdata.server = server;
2637 
2638 	if (server->flags & NFS4_MOUNT_UNSHARED)
2639 		compare_super = NULL;
2640 
2641 	/* -o noac implies -o sync */
2642 	if (server->flags & NFS_MOUNT_NOAC)
2643 		sb_mntdata.mntflags |= MS_SYNCHRONOUS;
2644 
2645 	/* Get a superblock - note that we may end up sharing one that already exists */
2646 	s = sget(&nfs4_fs_type, compare_super, nfs_set_super, &sb_mntdata);
2647 	if (IS_ERR(s)) {
2648 		error = PTR_ERR(s);
2649 		goto out_free;
2650 	}
2651 
2652 	if (s->s_fs_info != server) {
2653 		nfs_free_server(server);
2654 		server = NULL;
2655 	} else {
2656 		error = nfs_bdi_register(server);
2657 		if (error)
2658 			goto error_splat_bdi;
2659 	}
2660 
2661 	if (!s->s_root) {
2662 		/* initial superblock/root creation */
2663 		nfs4_fill_super(s);
2664 		nfs_fscache_get_super_cookie(
2665 			s, data ? data->fscache_uniq : NULL, NULL);
2666 	}
2667 
2668 	mntroot = nfs4_get_root(s, mntfh, dev_name);
2669 	if (IS_ERR(mntroot)) {
2670 		error = PTR_ERR(mntroot);
2671 		goto error_splat_super;
2672 	}
2673 
2674 	error = security_sb_set_mnt_opts(s, &data->lsm_opts);
2675 	if (error)
2676 		goto error_splat_root;
2677 
2678 	s->s_flags |= MS_ACTIVE;
2679 
2680 	security_free_mnt_opts(&data->lsm_opts);
2681 	nfs_free_fhandle(mntfh);
2682 	return mntroot;
2683 
2684 out:
2685 	security_free_mnt_opts(&data->lsm_opts);
2686 out_free_fh:
2687 	nfs_free_fhandle(mntfh);
2688 	return ERR_PTR(error);
2689 
2690 out_free:
2691 	nfs_free_server(server);
2692 	goto out;
2693 
2694 error_splat_root:
2695 	dput(mntroot);
2696 error_splat_super:
2697 	if (server && !s->s_root)
2698 		bdi_unregister(&server->backing_dev_info);
2699 error_splat_bdi:
2700 	deactivate_locked_super(s);
2701 	goto out;
2702 }
2703 
2704 static struct vfsmount *nfs_do_root_mount(struct file_system_type *fs_type,
2705 		int flags, void *data, const char *hostname)
2706 {
2707 	struct vfsmount *root_mnt;
2708 	char *root_devname;
2709 	size_t len;
2710 
2711 	len = strlen(hostname) + 3;
2712 	root_devname = kmalloc(len, GFP_KERNEL);
2713 	if (root_devname == NULL)
2714 		return ERR_PTR(-ENOMEM);
2715 	snprintf(root_devname, len, "%s:/", hostname);
2716 	root_mnt = vfs_kern_mount(fs_type, flags, root_devname, data);
2717 	kfree(root_devname);
2718 	return root_mnt;
2719 }
2720 
2721 struct nfs_referral_count {
2722 	struct list_head list;
2723 	const struct task_struct *task;
2724 	unsigned int referral_count;
2725 };
2726 
2727 static LIST_HEAD(nfs_referral_count_list);
2728 static DEFINE_SPINLOCK(nfs_referral_count_list_lock);
2729 
2730 static struct nfs_referral_count *nfs_find_referral_count(void)
2731 {
2732 	struct nfs_referral_count *p;
2733 
2734 	list_for_each_entry(p, &nfs_referral_count_list, list) {
2735 		if (p->task == current)
2736 			return p;
2737 	}
2738 	return NULL;
2739 }
2740 
2741 #define NFS_MAX_NESTED_REFERRALS 2
2742 
2743 static int nfs_referral_loop_protect(void)
2744 {
2745 	struct nfs_referral_count *p, *new;
2746 	int ret = -ENOMEM;
2747 
2748 	new = kmalloc(sizeof(*new), GFP_KERNEL);
2749 	if (!new)
2750 		goto out;
2751 	new->task = current;
2752 	new->referral_count = 1;
2753 
2754 	ret = 0;
2755 	spin_lock(&nfs_referral_count_list_lock);
2756 	p = nfs_find_referral_count();
2757 	if (p != NULL) {
2758 		if (p->referral_count >= NFS_MAX_NESTED_REFERRALS)
2759 			ret = -ELOOP;
2760 		else
2761 			p->referral_count++;
2762 	} else {
2763 		list_add(&new->list, &nfs_referral_count_list);
2764 		new = NULL;
2765 	}
2766 	spin_unlock(&nfs_referral_count_list_lock);
2767 	kfree(new);
2768 out:
2769 	return ret;
2770 }
2771 
2772 static void nfs_referral_loop_unprotect(void)
2773 {
2774 	struct nfs_referral_count *p;
2775 
2776 	spin_lock(&nfs_referral_count_list_lock);
2777 	p = nfs_find_referral_count();
2778 	p->referral_count--;
2779 	if (p->referral_count == 0)
2780 		list_del(&p->list);
2781 	else
2782 		p = NULL;
2783 	spin_unlock(&nfs_referral_count_list_lock);
2784 	kfree(p);
2785 }
2786 
2787 static struct dentry *nfs_follow_remote_path(struct vfsmount *root_mnt,
2788 		const char *export_path)
2789 {
2790 	struct mnt_namespace *ns_private;
2791 	struct super_block *s;
2792 	struct dentry *dentry;
2793 	struct path path;
2794 	int ret;
2795 
2796 	ns_private = create_mnt_ns(root_mnt);
2797 	ret = PTR_ERR(ns_private);
2798 	if (IS_ERR(ns_private))
2799 		goto out_mntput;
2800 
2801 	ret = nfs_referral_loop_protect();
2802 	if (ret != 0)
2803 		goto out_put_mnt_ns;
2804 
2805 	ret = vfs_path_lookup(root_mnt->mnt_root, root_mnt,
2806 			export_path, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path);
2807 
2808 	nfs_referral_loop_unprotect();
2809 	put_mnt_ns(ns_private);
2810 
2811 	if (ret != 0)
2812 		goto out_err;
2813 
2814 	s = path.mnt->mnt_sb;
2815 	atomic_inc(&s->s_active);
2816 	dentry = dget(path.dentry);
2817 
2818 	path_put(&path);
2819 	down_write(&s->s_umount);
2820 	return dentry;
2821 out_put_mnt_ns:
2822 	put_mnt_ns(ns_private);
2823 out_mntput:
2824 	mntput(root_mnt);
2825 out_err:
2826 	return ERR_PTR(ret);
2827 }
2828 
2829 static struct dentry *nfs4_try_mount(int flags, const char *dev_name,
2830 			 struct nfs_parsed_mount_data *data)
2831 {
2832 	char *export_path;
2833 	struct vfsmount *root_mnt;
2834 	struct dentry *res;
2835 
2836 	dfprintk(MOUNT, "--> nfs4_try_mount()\n");
2837 
2838 	export_path = data->nfs_server.export_path;
2839 	data->nfs_server.export_path = "/";
2840 	root_mnt = nfs_do_root_mount(&nfs4_remote_fs_type, flags, data,
2841 			data->nfs_server.hostname);
2842 	data->nfs_server.export_path = export_path;
2843 
2844 	res = ERR_CAST(root_mnt);
2845 	if (!IS_ERR(root_mnt))
2846 		res = nfs_follow_remote_path(root_mnt, export_path);
2847 
2848 	dfprintk(MOUNT, "<-- nfs4_try_mount() = %ld%s\n",
2849 			IS_ERR(res) ? PTR_ERR(res) : 0,
2850 			IS_ERR(res) ? " [error]" : "");
2851 	return res;
2852 }
2853 
2854 /*
2855  * Get the superblock for an NFS4 mountpoint
2856  */
2857 static struct dentry *nfs4_mount(struct file_system_type *fs_type,
2858 	int flags, const char *dev_name, void *raw_data)
2859 {
2860 	struct nfs_parsed_mount_data *data;
2861 	int error = -ENOMEM;
2862 	struct dentry *res = ERR_PTR(-ENOMEM);
2863 
2864 	data = nfs_alloc_parsed_mount_data(4);
2865 	if (data == NULL)
2866 		goto out_free_data;
2867 
2868 	/* Validate the mount data */
2869 	error = nfs4_validate_mount_data(raw_data, data, dev_name);
2870 	if (error < 0) {
2871 		res = ERR_PTR(error);
2872 		goto out;
2873 	}
2874 
2875 	res = nfs4_try_mount(flags, dev_name, data);
2876 	if (IS_ERR(res))
2877 		error = PTR_ERR(res);
2878 
2879 out:
2880 	kfree(data->client_address);
2881 	kfree(data->nfs_server.export_path);
2882 	kfree(data->nfs_server.hostname);
2883 	kfree(data->fscache_uniq);
2884 out_free_data:
2885 	kfree(data);
2886 	dprintk("<-- nfs4_mount() = %d%s\n", error,
2887 			error != 0 ? " [error]" : "");
2888 	return res;
2889 }
2890 
2891 static void nfs4_kill_super(struct super_block *sb)
2892 {
2893 	struct nfs_server *server = NFS_SB(sb);
2894 
2895 	dprintk("--> %s\n", __func__);
2896 	nfs_super_return_all_delegations(sb);
2897 	kill_anon_super(sb);
2898 	nfs_fscache_release_super_cookie(sb);
2899 	nfs_free_server(server);
2900 	dprintk("<-- %s\n", __func__);
2901 }
2902 
2903 /*
2904  * Clone an NFS4 server record on xdev traversal (FSID-change)
2905  */
2906 static struct dentry *
2907 nfs4_xdev_mount(struct file_system_type *fs_type, int flags,
2908 		 const char *dev_name, void *raw_data)
2909 {
2910 	struct nfs_clone_mount *data = raw_data;
2911 	struct super_block *s;
2912 	struct nfs_server *server;
2913 	struct dentry *mntroot;
2914 	int (*compare_super)(struct super_block *, void *) = nfs_compare_super;
2915 	struct nfs_sb_mountdata sb_mntdata = {
2916 		.mntflags = flags,
2917 	};
2918 	int error;
2919 
2920 	dprintk("--> nfs4_xdev_mount()\n");
2921 
2922 	/* create a new volume representation */
2923 	server = nfs_clone_server(NFS_SB(data->sb), data->fh, data->fattr);
2924 	if (IS_ERR(server)) {
2925 		error = PTR_ERR(server);
2926 		goto out_err_noserver;
2927 	}
2928 	sb_mntdata.server = server;
2929 
2930 	if (server->flags & NFS4_MOUNT_UNSHARED)
2931 		compare_super = NULL;
2932 
2933 	/* -o noac implies -o sync */
2934 	if (server->flags & NFS_MOUNT_NOAC)
2935 		sb_mntdata.mntflags |= MS_SYNCHRONOUS;
2936 
2937 	/* Get a superblock - note that we may end up sharing one that already exists */
2938 	s = sget(&nfs4_fs_type, compare_super, nfs_set_super, &sb_mntdata);
2939 	if (IS_ERR(s)) {
2940 		error = PTR_ERR(s);
2941 		goto out_err_nosb;
2942 	}
2943 
2944 	if (s->s_fs_info != server) {
2945 		nfs_free_server(server);
2946 		server = NULL;
2947 	} else {
2948 		error = nfs_bdi_register(server);
2949 		if (error)
2950 			goto error_splat_bdi;
2951 	}
2952 
2953 	if (!s->s_root) {
2954 		/* initial superblock/root creation */
2955 		nfs4_clone_super(s, data->sb);
2956 		nfs_fscache_get_super_cookie(s, NULL, data);
2957 	}
2958 
2959 	mntroot = nfs4_get_root(s, data->fh, dev_name);
2960 	if (IS_ERR(mntroot)) {
2961 		error = PTR_ERR(mntroot);
2962 		goto error_splat_super;
2963 	}
2964 	if (mntroot->d_inode->i_op != NFS_SB(s)->nfs_client->rpc_ops->dir_inode_ops) {
2965 		dput(mntroot);
2966 		error = -ESTALE;
2967 		goto error_splat_super;
2968 	}
2969 
2970 	s->s_flags |= MS_ACTIVE;
2971 
2972 	security_sb_clone_mnt_opts(data->sb, s);
2973 
2974 	dprintk("<-- nfs4_xdev_mount() = 0\n");
2975 	return mntroot;
2976 
2977 out_err_nosb:
2978 	nfs_free_server(server);
2979 out_err_noserver:
2980 	dprintk("<-- nfs4_xdev_mount() = %d [error]\n", error);
2981 	return ERR_PTR(error);
2982 
2983 error_splat_super:
2984 	if (server && !s->s_root)
2985 		bdi_unregister(&server->backing_dev_info);
2986 error_splat_bdi:
2987 	deactivate_locked_super(s);
2988 	dprintk("<-- nfs4_xdev_mount() = %d [splat]\n", error);
2989 	return ERR_PTR(error);
2990 }
2991 
2992 static struct dentry *
2993 nfs4_remote_referral_mount(struct file_system_type *fs_type, int flags,
2994 			   const char *dev_name, void *raw_data)
2995 {
2996 	struct nfs_clone_mount *data = raw_data;
2997 	struct super_block *s;
2998 	struct nfs_server *server;
2999 	struct dentry *mntroot;
3000 	struct nfs_fh *mntfh;
3001 	int (*compare_super)(struct super_block *, void *) = nfs_compare_super;
3002 	struct nfs_sb_mountdata sb_mntdata = {
3003 		.mntflags = flags,
3004 	};
3005 	int error = -ENOMEM;
3006 
3007 	dprintk("--> nfs4_referral_get_sb()\n");
3008 
3009 	mntfh = nfs_alloc_fhandle();
3010 	if (mntfh == NULL)
3011 		goto out_err_nofh;
3012 
3013 	/* create a new volume representation */
3014 	server = nfs4_create_referral_server(data, mntfh);
3015 	if (IS_ERR(server)) {
3016 		error = PTR_ERR(server);
3017 		goto out_err_noserver;
3018 	}
3019 	sb_mntdata.server = server;
3020 
3021 	if (server->flags & NFS4_MOUNT_UNSHARED)
3022 		compare_super = NULL;
3023 
3024 	/* -o noac implies -o sync */
3025 	if (server->flags & NFS_MOUNT_NOAC)
3026 		sb_mntdata.mntflags |= MS_SYNCHRONOUS;
3027 
3028 	/* Get a superblock - note that we may end up sharing one that already exists */
3029 	s = sget(&nfs4_fs_type, compare_super, nfs_set_super, &sb_mntdata);
3030 	if (IS_ERR(s)) {
3031 		error = PTR_ERR(s);
3032 		goto out_err_nosb;
3033 	}
3034 
3035 	if (s->s_fs_info != server) {
3036 		nfs_free_server(server);
3037 		server = NULL;
3038 	} else {
3039 		error = nfs_bdi_register(server);
3040 		if (error)
3041 			goto error_splat_bdi;
3042 	}
3043 
3044 	if (!s->s_root) {
3045 		/* initial superblock/root creation */
3046 		nfs4_fill_super(s);
3047 		nfs_fscache_get_super_cookie(s, NULL, data);
3048 	}
3049 
3050 	mntroot = nfs4_get_root(s, mntfh, dev_name);
3051 	if (IS_ERR(mntroot)) {
3052 		error = PTR_ERR(mntroot);
3053 		goto error_splat_super;
3054 	}
3055 	if (mntroot->d_inode->i_op != NFS_SB(s)->nfs_client->rpc_ops->dir_inode_ops) {
3056 		dput(mntroot);
3057 		error = -ESTALE;
3058 		goto error_splat_super;
3059 	}
3060 
3061 	s->s_flags |= MS_ACTIVE;
3062 
3063 	security_sb_clone_mnt_opts(data->sb, s);
3064 
3065 	nfs_free_fhandle(mntfh);
3066 	dprintk("<-- nfs4_referral_get_sb() = 0\n");
3067 	return mntroot;
3068 
3069 out_err_nosb:
3070 	nfs_free_server(server);
3071 out_err_noserver:
3072 	nfs_free_fhandle(mntfh);
3073 out_err_nofh:
3074 	dprintk("<-- nfs4_referral_get_sb() = %d [error]\n", error);
3075 	return ERR_PTR(error);
3076 
3077 error_splat_super:
3078 	if (server && !s->s_root)
3079 		bdi_unregister(&server->backing_dev_info);
3080 error_splat_bdi:
3081 	deactivate_locked_super(s);
3082 	nfs_free_fhandle(mntfh);
3083 	dprintk("<-- nfs4_referral_get_sb() = %d [splat]\n", error);
3084 	return ERR_PTR(error);
3085 }
3086 
3087 /*
3088  * Create an NFS4 server record on referral traversal
3089  */
3090 static struct dentry *nfs4_referral_mount(struct file_system_type *fs_type,
3091 		int flags, const char *dev_name, void *raw_data)
3092 {
3093 	struct nfs_clone_mount *data = raw_data;
3094 	char *export_path;
3095 	struct vfsmount *root_mnt;
3096 	struct dentry *res;
3097 
3098 	dprintk("--> nfs4_referral_mount()\n");
3099 
3100 	export_path = data->mnt_path;
3101 	data->mnt_path = "/";
3102 
3103 	root_mnt = nfs_do_root_mount(&nfs4_remote_referral_fs_type,
3104 			flags, data, data->hostname);
3105 	data->mnt_path = export_path;
3106 
3107 	res = ERR_CAST(root_mnt);
3108 	if (!IS_ERR(root_mnt))
3109 		res = nfs_follow_remote_path(root_mnt, export_path);
3110 	dprintk("<-- nfs4_referral_mount() = %ld%s\n",
3111 			IS_ERR(res) ? PTR_ERR(res) : 0,
3112 			IS_ERR(res) ? " [error]" : "");
3113 	return res;
3114 }
3115 
3116 #endif /* CONFIG_NFS_V4 */
3117