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1/*
2 * NFS server file handle treatment.
3 *
4 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
5 * Portions Copyright (C) 1999 G. Allen Morris III <gam3@acm.org>
6 * Extensive rewrite by Neil Brown <neilb@cse.unsw.edu.au> Southern-Spring 1999
7 * ... and again Southern-Winter 2001 to support export_operations
8 */
9
10#include <linux/exportfs.h>
11
12#include <linux/sunrpc/svcauth_gss.h>
13#include "nfsd.h"
14#include "vfs.h"
15#include "auth.h"
16
17#define NFSDDBG_FACILITY		NFSDDBG_FH
18
19
20/*
21 * our acceptability function.
22 * if NOSUBTREECHECK, accept anything
23 * if not, require that we can walk up to exp->ex_dentry
24 * doing some checks on the 'x' bits
25 */
26static int nfsd_acceptable(void *expv, struct dentry *dentry)
27{
28	struct svc_export *exp = expv;
29	int rv;
30	struct dentry *tdentry;
31	struct dentry *parent;
32
33	if (exp->ex_flags & NFSEXP_NOSUBTREECHECK)
34		return 1;
35
36	tdentry = dget(dentry);
37	while (tdentry != exp->ex_path.dentry && !IS_ROOT(tdentry)) {
38		/* make sure parents give x permission to user */
39		int err;
40		parent = dget_parent(tdentry);
41		err = inode_permission(parent->d_inode, MAY_EXEC);
42		if (err < 0) {
43			dput(parent);
44			break;
45		}
46		dput(tdentry);
47		tdentry = parent;
48	}
49	if (tdentry != exp->ex_path.dentry)
50		dprintk("nfsd_acceptable failed at %p %s\n", tdentry, tdentry->d_name.name);
51	rv = (tdentry == exp->ex_path.dentry);
52	dput(tdentry);
53	return rv;
54}
55
56/* Type check. The correct error return for type mismatches does not seem to be
57 * generally agreed upon. SunOS seems to use EISDIR if file isn't S_IFREG; a
58 * comment in the NFSv3 spec says this is incorrect (implementation notes for
59 * the write call).
60 */
61static inline __be32
62nfsd_mode_check(struct svc_rqst *rqstp, umode_t mode, int type)
63{
64	/* Type can be negative when creating hardlinks - not to a dir */
65	if (type > 0 && (mode & S_IFMT) != type) {
66		if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK)
67			return nfserr_symlink;
68		else if (type == S_IFDIR)
69			return nfserr_notdir;
70		else if ((mode & S_IFMT) == S_IFDIR)
71			return nfserr_isdir;
72		else
73			return nfserr_inval;
74	}
75	if (type < 0 && (mode & S_IFMT) == -type) {
76		if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK)
77			return nfserr_symlink;
78		else if (type == -S_IFDIR)
79			return nfserr_isdir;
80		else
81			return nfserr_notdir;
82	}
83	return 0;
84}
85
86static __be32 nfsd_setuser_and_check_port(struct svc_rqst *rqstp,
87					  struct svc_export *exp)
88{
89	int flags = nfsexp_flags(rqstp, exp);
90
91	/* Check if the request originated from a secure port. */
92	if (!rqstp->rq_secure && !(flags & NFSEXP_INSECURE_PORT)) {
93		RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
94		dprintk(KERN_WARNING
95		       "nfsd: request from insecure port %s!\n",
96		       svc_print_addr(rqstp, buf, sizeof(buf)));
97		return nfserr_perm;
98	}
99
100	/* Set user creds for this exportpoint */
101	return nfserrno(nfsd_setuser(rqstp, exp));
102}
103
104static inline __be32 check_pseudo_root(struct svc_rqst *rqstp,
105	struct dentry *dentry, struct svc_export *exp)
106{
107	if (!(exp->ex_flags & NFSEXP_V4ROOT))
108		return nfs_ok;
109	/*
110	 * v2/v3 clients have no need for the V4ROOT export--they use
111	 * the mount protocl instead; also, further V4ROOT checks may be
112	 * in v4-specific code, in which case v2/v3 clients could bypass
113	 * them.
114	 */
115	if (!nfsd_v4client(rqstp))
116		return nfserr_stale;
117	/*
118	 * We're exposing only the directories and symlinks that have to be
119	 * traversed on the way to real exports:
120	 */
121	if (unlikely(!S_ISDIR(dentry->d_inode->i_mode) &&
122		     !S_ISLNK(dentry->d_inode->i_mode)))
123		return nfserr_stale;
124	/*
125	 * A pseudoroot export gives permission to access only one
126	 * single directory; the kernel has to make another upcall
127	 * before granting access to anything else under it:
128	 */
129	if (unlikely(dentry != exp->ex_path.dentry))
130		return nfserr_stale;
131	return nfs_ok;
132}
133
134/*
135 * Use the given filehandle to look up the corresponding export and
136 * dentry.  On success, the results are used to set fh_export and
137 * fh_dentry.
138 */
139static __be32 nfsd_set_fh_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp)
140{
141	struct knfsd_fh	*fh = &fhp->fh_handle;
142	struct fid *fid = NULL, sfid;
143	struct svc_export *exp;
144	struct dentry *dentry;
145	int fileid_type;
146	int data_left = fh->fh_size/4;
147	__be32 error;
148
149	error = nfserr_stale;
150	if (rqstp->rq_vers > 2)
151		error = nfserr_badhandle;
152	if (rqstp->rq_vers == 4 && fh->fh_size == 0)
153		return nfserr_nofilehandle;
154
155	if (fh->fh_version == 1) {
156		int len;
157
158		if (--data_left < 0)
159			return error;
160		if (fh->fh_auth_type != 0)
161			return error;
162		len = key_len(fh->fh_fsid_type) / 4;
163		if (len == 0)
164			return error;
165		if  (fh->fh_fsid_type == FSID_MAJOR_MINOR) {
166			/* deprecated, convert to type 3 */
167			len = key_len(FSID_ENCODE_DEV)/4;
168			fh->fh_fsid_type = FSID_ENCODE_DEV;
169			fh->fh_fsid[0] = new_encode_dev(MKDEV(ntohl(fh->fh_fsid[0]), ntohl(fh->fh_fsid[1])));
170			fh->fh_fsid[1] = fh->fh_fsid[2];
171		}
172		data_left -= len;
173		if (data_left < 0)
174			return error;
175		exp = rqst_exp_find(rqstp, fh->fh_fsid_type, fh->fh_auth);
176		fid = (struct fid *)(fh->fh_auth + len);
177	} else {
178		__u32 tfh[2];
179		dev_t xdev;
180		ino_t xino;
181
182		if (fh->fh_size != NFS_FHSIZE)
183			return error;
184		/* assume old filehandle format */
185		xdev = old_decode_dev(fh->ofh_xdev);
186		xino = u32_to_ino_t(fh->ofh_xino);
187		mk_fsid(FSID_DEV, tfh, xdev, xino, 0, NULL);
188		exp = rqst_exp_find(rqstp, FSID_DEV, tfh);
189	}
190
191	error = nfserr_stale;
192	if (PTR_ERR(exp) == -ENOENT)
193		return error;
194
195	if (IS_ERR(exp))
196		return nfserrno(PTR_ERR(exp));
197
198	if (exp->ex_flags & NFSEXP_NOSUBTREECHECK) {
199		/* Elevate privileges so that the lack of 'r' or 'x'
200		 * permission on some parent directory will
201		 * not stop exportfs_decode_fh from being able
202		 * to reconnect a directory into the dentry cache.
203		 * The same problem can affect "SUBTREECHECK" exports,
204		 * but as nfsd_acceptable depends on correct
205		 * access control settings being in effect, we cannot
206		 * fix that case easily.
207		 */
208		struct cred *new = prepare_creds();
209		if (!new)
210			return nfserrno(-ENOMEM);
211		new->cap_effective =
212			cap_raise_nfsd_set(new->cap_effective,
213					   new->cap_permitted);
214		put_cred(override_creds(new));
215		put_cred(new);
216	} else {
217		error = nfsd_setuser_and_check_port(rqstp, exp);
218		if (error)
219			goto out;
220	}
221
222	/*
223	 * Look up the dentry using the NFS file handle.
224	 */
225	error = nfserr_stale;
226	if (rqstp->rq_vers > 2)
227		error = nfserr_badhandle;
228
229	if (fh->fh_version != 1) {
230		sfid.i32.ino = fh->ofh_ino;
231		sfid.i32.gen = fh->ofh_generation;
232		sfid.i32.parent_ino = fh->ofh_dirino;
233		fid = &sfid;
234		data_left = 3;
235		if (fh->ofh_dirino == 0)
236			fileid_type = FILEID_INO32_GEN;
237		else
238			fileid_type = FILEID_INO32_GEN_PARENT;
239	} else
240		fileid_type = fh->fh_fileid_type;
241
242	if (fileid_type == FILEID_ROOT)
243		dentry = dget(exp->ex_path.dentry);
244	else {
245		dentry = exportfs_decode_fh(exp->ex_path.mnt, fid,
246				data_left, fileid_type,
247				nfsd_acceptable, exp);
248	}
249	if (dentry == NULL)
250		goto out;
251	if (IS_ERR(dentry)) {
252		if (PTR_ERR(dentry) != -EINVAL)
253			error = nfserrno(PTR_ERR(dentry));
254		goto out;
255	}
256
257	if (S_ISDIR(dentry->d_inode->i_mode) &&
258			(dentry->d_flags & DCACHE_DISCONNECTED)) {
259		printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %s/%s\n",
260				dentry->d_parent->d_name.name, dentry->d_name.name);
261	}
262
263	fhp->fh_dentry = dentry;
264	fhp->fh_export = exp;
265	return 0;
266out:
267	exp_put(exp);
268	return error;
269}
270
271/**
272 * fh_verify - filehandle lookup and access checking
273 * @rqstp: pointer to current rpc request
274 * @fhp: filehandle to be verified
275 * @type: expected type of object pointed to by filehandle
276 * @access: type of access needed to object
277 *
278 * Look up a dentry from the on-the-wire filehandle, check the client's
279 * access to the export, and set the current task's credentials.
280 *
281 * Regardless of success or failure of fh_verify(), fh_put() should be
282 * called on @fhp when the caller is finished with the filehandle.
283 *
284 * fh_verify() may be called multiple times on a given filehandle, for
285 * example, when processing an NFSv4 compound.  The first call will look
286 * up a dentry using the on-the-wire filehandle.  Subsequent calls will
287 * skip the lookup and just perform the other checks and possibly change
288 * the current task's credentials.
289 *
290 * @type specifies the type of object expected using one of the S_IF*
291 * constants defined in include/linux/stat.h.  The caller may use zero
292 * to indicate that it doesn't care, or a negative integer to indicate
293 * that it expects something not of the given type.
294 *
295 * @access is formed from the NFSD_MAY_* constants defined in
296 * include/linux/nfsd/nfsd.h.
297 */
298__be32
299fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access)
300{
301	struct svc_export *exp;
302	struct dentry	*dentry;
303	__be32		error;
304
305	dprintk("nfsd: fh_verify(%s)\n", SVCFH_fmt(fhp));
306
307	if (!fhp->fh_dentry) {
308		error = nfsd_set_fh_dentry(rqstp, fhp);
309		if (error)
310			goto out;
311	}
312	dentry = fhp->fh_dentry;
313	exp = fhp->fh_export;
314	/*
315	 * We still have to do all these permission checks, even when
316	 * fh_dentry is already set:
317	 * 	- fh_verify may be called multiple times with different
318	 * 	  "access" arguments (e.g. nfsd_proc_create calls
319	 * 	  fh_verify(...,NFSD_MAY_EXEC) first, then later (in
320	 * 	  nfsd_create) calls fh_verify(...,NFSD_MAY_CREATE).
321	 *	- in the NFSv4 case, the filehandle may have been filled
322	 *	  in by fh_compose, and given a dentry, but further
323	 *	  compound operations performed with that filehandle
324	 *	  still need permissions checks.  In the worst case, a
325	 *	  mountpoint crossing may have changed the export
326	 *	  options, and we may now need to use a different uid
327	 *	  (for example, if different id-squashing options are in
328	 *	  effect on the new filesystem).
329	 */
330	error = check_pseudo_root(rqstp, dentry, exp);
331	if (error)
332		goto out;
333
334	error = nfsd_setuser_and_check_port(rqstp, exp);
335	if (error)
336		goto out;
337
338	error = nfsd_mode_check(rqstp, dentry->d_inode->i_mode, type);
339	if (error)
340		goto out;
341
342	/*
343	 * pseudoflavor restrictions are not enforced on NLM,
344	 * which clients virtually always use auth_sys for,
345	 * even while using RPCSEC_GSS for NFS.
346	 */
347	if (access & NFSD_MAY_LOCK)
348		goto skip_pseudoflavor_check;
349	/*
350	 * Clients may expect to be able to use auth_sys during mount,
351	 * even if they use gss for everything else; see section 2.3.2
352	 * of rfc 2623.
353	 */
354	if (access & NFSD_MAY_BYPASS_GSS_ON_ROOT
355			&& exp->ex_path.dentry == dentry)
356		goto skip_pseudoflavor_check;
357
358	error = check_nfsd_access(exp, rqstp);
359	if (error)
360		goto out;
361
362skip_pseudoflavor_check:
363	/* Finally, check access permissions. */
364	error = nfsd_permission(rqstp, exp, dentry, access);
365
366	if (error) {
367		dprintk("fh_verify: %s/%s permission failure, "
368			"acc=%x, error=%d\n",
369			dentry->d_parent->d_name.name,
370			dentry->d_name.name,
371			access, ntohl(error));
372	}
373out:
374	if (error == nfserr_stale)
375		nfsdstats.fh_stale++;
376	return error;
377}
378
379
380/*
381 * Compose a file handle for an NFS reply.
382 *
383 * Note that when first composed, the dentry may not yet have
384 * an inode.  In this case a call to fh_update should be made
385 * before the fh goes out on the wire ...
386 */
387static void _fh_update(struct svc_fh *fhp, struct svc_export *exp,
388		struct dentry *dentry)
389{
390	if (dentry != exp->ex_path.dentry) {
391		struct fid *fid = (struct fid *)
392			(fhp->fh_handle.fh_auth + fhp->fh_handle.fh_size/4 - 1);
393		int maxsize = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
394		int subtreecheck = !(exp->ex_flags & NFSEXP_NOSUBTREECHECK);
395
396		fhp->fh_handle.fh_fileid_type =
397			exportfs_encode_fh(dentry, fid, &maxsize, subtreecheck);
398		fhp->fh_handle.fh_size += maxsize * 4;
399	} else {
400		fhp->fh_handle.fh_fileid_type = FILEID_ROOT;
401	}
402}
403
404/*
405 * for composing old style file handles
406 */
407static inline void _fh_update_old(struct dentry *dentry,
408				  struct svc_export *exp,
409				  struct knfsd_fh *fh)
410{
411	fh->ofh_ino = ino_t_to_u32(dentry->d_inode->i_ino);
412	fh->ofh_generation = dentry->d_inode->i_generation;
413	if (S_ISDIR(dentry->d_inode->i_mode) ||
414	    (exp->ex_flags & NFSEXP_NOSUBTREECHECK))
415		fh->ofh_dirino = 0;
416}
417
418static bool is_root_export(struct svc_export *exp)
419{
420	return exp->ex_path.dentry == exp->ex_path.dentry->d_sb->s_root;
421}
422
423static struct super_block *exp_sb(struct svc_export *exp)
424{
425	return exp->ex_path.dentry->d_inode->i_sb;
426}
427
428static bool fsid_type_ok_for_exp(u8 fsid_type, struct svc_export *exp)
429{
430	switch (fsid_type) {
431	case FSID_DEV:
432		if (!old_valid_dev(exp_sb(exp)->s_dev))
433			return 0;
434		/* FALL THROUGH */
435	case FSID_MAJOR_MINOR:
436	case FSID_ENCODE_DEV:
437		return exp_sb(exp)->s_type->fs_flags & FS_REQUIRES_DEV;
438	case FSID_NUM:
439		return exp->ex_flags & NFSEXP_FSID;
440	case FSID_UUID8:
441	case FSID_UUID16:
442		if (!is_root_export(exp))
443			return 0;
444		/* fall through */
445	case FSID_UUID4_INUM:
446	case FSID_UUID16_INUM:
447		return exp->ex_uuid != NULL;
448	}
449	return 1;
450}
451
452
453static void set_version_and_fsid_type(struct svc_fh *fhp, struct svc_export *exp, struct svc_fh *ref_fh)
454{
455	u8 version;
456	u8 fsid_type;
457retry:
458	version = 1;
459	if (ref_fh && ref_fh->fh_export == exp) {
460		version = ref_fh->fh_handle.fh_version;
461		fsid_type = ref_fh->fh_handle.fh_fsid_type;
462
463		ref_fh = NULL;
464
465		switch (version) {
466		case 0xca:
467			fsid_type = FSID_DEV;
468			break;
469		case 1:
470			break;
471		default:
472			goto retry;
473		}
474
475		/*
476		 * As the fsid -> filesystem mapping was guided by
477		 * user-space, there is no guarantee that the filesystem
478		 * actually supports that fsid type. If it doesn't we
479		 * loop around again without ref_fh set.
480		 */
481		if (!fsid_type_ok_for_exp(fsid_type, exp))
482			goto retry;
483	} else if (exp->ex_flags & NFSEXP_FSID) {
484		fsid_type = FSID_NUM;
485	} else if (exp->ex_uuid) {
486		if (fhp->fh_maxsize >= 64) {
487			if (is_root_export(exp))
488				fsid_type = FSID_UUID16;
489			else
490				fsid_type = FSID_UUID16_INUM;
491		} else {
492			if (is_root_export(exp))
493				fsid_type = FSID_UUID8;
494			else
495				fsid_type = FSID_UUID4_INUM;
496		}
497	} else if (!old_valid_dev(exp_sb(exp)->s_dev))
498		/* for newer device numbers, we must use a newer fsid format */
499		fsid_type = FSID_ENCODE_DEV;
500	else
501		fsid_type = FSID_DEV;
502	fhp->fh_handle.fh_version = version;
503	if (version)
504		fhp->fh_handle.fh_fsid_type = fsid_type;
505}
506
507__be32
508fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry,
509	   struct svc_fh *ref_fh)
510{
511	/* ref_fh is a reference file handle.
512	 * if it is non-null and for the same filesystem, then we should compose
513	 * a filehandle which is of the same version, where possible.
514	 * Currently, that means that if ref_fh->fh_handle.fh_version == 0xca
515	 * Then create a 32byte filehandle using nfs_fhbase_old
516	 *
517	 */
518
519	struct inode * inode = dentry->d_inode;
520	struct dentry *parent = dentry->d_parent;
521	__u32 *datap;
522	dev_t ex_dev = exp_sb(exp)->s_dev;
523
524	dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %s/%s, ino=%ld)\n",
525		MAJOR(ex_dev), MINOR(ex_dev),
526		(long) exp->ex_path.dentry->d_inode->i_ino,
527		parent->d_name.name, dentry->d_name.name,
528		(inode ? inode->i_ino : 0));
529
530	/* Choose filehandle version and fsid type based on
531	 * the reference filehandle (if it is in the same export)
532	 * or the export options.
533	 */
534	 set_version_and_fsid_type(fhp, exp, ref_fh);
535
536	if (ref_fh == fhp)
537		fh_put(ref_fh);
538
539	if (fhp->fh_locked || fhp->fh_dentry) {
540		printk(KERN_ERR "fh_compose: fh %s/%s not initialized!\n",
541		       parent->d_name.name, dentry->d_name.name);
542	}
543	if (fhp->fh_maxsize < NFS_FHSIZE)
544		printk(KERN_ERR "fh_compose: called with maxsize %d! %s/%s\n",
545		       fhp->fh_maxsize,
546		       parent->d_name.name, dentry->d_name.name);
547
548	fhp->fh_dentry = dget(dentry); /* our internal copy */
549	fhp->fh_export = exp;
550	cache_get(&exp->h);
551
552	if (fhp->fh_handle.fh_version == 0xca) {
553		/* old style filehandle please */
554		memset(&fhp->fh_handle.fh_base, 0, NFS_FHSIZE);
555		fhp->fh_handle.fh_size = NFS_FHSIZE;
556		fhp->fh_handle.ofh_dcookie = 0xfeebbaca;
557		fhp->fh_handle.ofh_dev =  old_encode_dev(ex_dev);
558		fhp->fh_handle.ofh_xdev = fhp->fh_handle.ofh_dev;
559		fhp->fh_handle.ofh_xino =
560			ino_t_to_u32(exp->ex_path.dentry->d_inode->i_ino);
561		fhp->fh_handle.ofh_dirino = ino_t_to_u32(parent_ino(dentry));
562		if (inode)
563			_fh_update_old(dentry, exp, &fhp->fh_handle);
564	} else {
565		int len;
566		fhp->fh_handle.fh_auth_type = 0;
567		datap = fhp->fh_handle.fh_auth+0;
568		mk_fsid(fhp->fh_handle.fh_fsid_type, datap, ex_dev,
569			exp->ex_path.dentry->d_inode->i_ino,
570			exp->ex_fsid, exp->ex_uuid);
571
572		len = key_len(fhp->fh_handle.fh_fsid_type);
573		datap += len/4;
574		fhp->fh_handle.fh_size = 4 + len;
575
576		if (inode)
577			_fh_update(fhp, exp, dentry);
578		if (fhp->fh_handle.fh_fileid_type == 255) {
579			fh_put(fhp);
580			return nfserr_opnotsupp;
581		}
582	}
583
584	return 0;
585}
586
587/*
588 * Update file handle information after changing a dentry.
589 * This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create
590 */
591__be32
592fh_update(struct svc_fh *fhp)
593{
594	struct dentry *dentry;
595
596	if (!fhp->fh_dentry)
597		goto out_bad;
598
599	dentry = fhp->fh_dentry;
600	if (!dentry->d_inode)
601		goto out_negative;
602	if (fhp->fh_handle.fh_version != 1) {
603		_fh_update_old(dentry, fhp->fh_export, &fhp->fh_handle);
604	} else {
605		if (fhp->fh_handle.fh_fileid_type != FILEID_ROOT)
606			goto out;
607
608		_fh_update(fhp, fhp->fh_export, dentry);
609		if (fhp->fh_handle.fh_fileid_type == 255)
610			return nfserr_opnotsupp;
611	}
612out:
613	return 0;
614
615out_bad:
616	printk(KERN_ERR "fh_update: fh not verified!\n");
617	goto out;
618out_negative:
619	printk(KERN_ERR "fh_update: %s/%s still negative!\n",
620		dentry->d_parent->d_name.name, dentry->d_name.name);
621	goto out;
622}
623
624/*
625 * Release a file handle.
626 */
627void
628fh_put(struct svc_fh *fhp)
629{
630	struct dentry * dentry = fhp->fh_dentry;
631	struct svc_export * exp = fhp->fh_export;
632	if (dentry) {
633		fh_unlock(fhp);
634		fhp->fh_dentry = NULL;
635		dput(dentry);
636#ifdef CONFIG_NFSD_V3
637		fhp->fh_pre_saved = 0;
638		fhp->fh_post_saved = 0;
639#endif
640	}
641	if (exp) {
642		cache_put(&exp->h, &svc_export_cache);
643		fhp->fh_export = NULL;
644	}
645	return;
646}
647
648/*
649 * Shorthand for dprintk()'s
650 */
651char * SVCFH_fmt(struct svc_fh *fhp)
652{
653	struct knfsd_fh *fh = &fhp->fh_handle;
654
655	static char buf[80];
656	sprintf(buf, "%d: %08x %08x %08x %08x %08x %08x",
657		fh->fh_size,
658		fh->fh_base.fh_pad[0],
659		fh->fh_base.fh_pad[1],
660		fh->fh_base.fh_pad[2],
661		fh->fh_base.fh_pad[3],
662		fh->fh_base.fh_pad[4],
663		fh->fh_base.fh_pad[5]);
664	return buf;
665}
666
667enum fsid_source fsid_source(struct svc_fh *fhp)
668{
669	if (fhp->fh_handle.fh_version != 1)
670		return FSIDSOURCE_DEV;
671	switch(fhp->fh_handle.fh_fsid_type) {
672	case FSID_DEV:
673	case FSID_ENCODE_DEV:
674	case FSID_MAJOR_MINOR:
675		if (exp_sb(fhp->fh_export)->s_type->fs_flags & FS_REQUIRES_DEV)
676			return FSIDSOURCE_DEV;
677		break;
678	case FSID_NUM:
679		if (fhp->fh_export->ex_flags & NFSEXP_FSID)
680			return FSIDSOURCE_FSID;
681		break;
682	default:
683		break;
684	}
685	/* either a UUID type filehandle, or the filehandle doesn't
686	 * match the export.
687	 */
688	if (fhp->fh_export->ex_flags & NFSEXP_FSID)
689		return FSIDSOURCE_FSID;
690	if (fhp->fh_export->ex_uuid)
691		return FSIDSOURCE_UUID;
692	return FSIDSOURCE_DEV;
693}
694