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(d_inode(parent), 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 %pd\n", tdentry, tdentry);
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, umode_t requested)
63{
64	mode &= S_IFMT;
65
66	if (requested == 0) /* the caller doesn't care */
67		return nfs_ok;
68	if (mode == requested)
69		return nfs_ok;
70	/*
71	 * v4 has an error more specific than err_notdir which we should
72	 * return in preference to err_notdir:
73	 */
74	if (rqstp->rq_vers == 4 && mode == S_IFLNK)
75		return nfserr_symlink;
76	if (requested == S_IFDIR)
77		return nfserr_notdir;
78	if (mode == S_IFDIR)
79		return nfserr_isdir;
80	return nfserr_inval;
81}
82
83static __be32 nfsd_setuser_and_check_port(struct svc_rqst *rqstp,
84					  struct svc_export *exp)
85{
86	int flags = nfsexp_flags(rqstp, exp);
87
88	/* Check if the request originated from a secure port. */
89	if (!test_bit(RQ_SECURE, &rqstp->rq_flags) && !(flags & NFSEXP_INSECURE_PORT)) {
90		RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
91		dprintk("nfsd: request from insecure port %s!\n",
92		        svc_print_addr(rqstp, buf, sizeof(buf)));
93		return nfserr_perm;
94	}
95
96	/* Set user creds for this exportpoint */
97	return nfserrno(nfsd_setuser(rqstp, exp));
98}
99
100static inline __be32 check_pseudo_root(struct svc_rqst *rqstp,
101	struct dentry *dentry, struct svc_export *exp)
102{
103	if (!(exp->ex_flags & NFSEXP_V4ROOT))
104		return nfs_ok;
105	/*
106	 * v2/v3 clients have no need for the V4ROOT export--they use
107	 * the mount protocl instead; also, further V4ROOT checks may be
108	 * in v4-specific code, in which case v2/v3 clients could bypass
109	 * them.
110	 */
111	if (!nfsd_v4client(rqstp))
112		return nfserr_stale;
113	/*
114	 * We're exposing only the directories and symlinks that have to be
115	 * traversed on the way to real exports:
116	 */
117	if (unlikely(!d_is_dir(dentry) &&
118		     !d_is_symlink(dentry)))
119		return nfserr_stale;
120	/*
121	 * A pseudoroot export gives permission to access only one
122	 * single directory; the kernel has to make another upcall
123	 * before granting access to anything else under it:
124	 */
125	if (unlikely(dentry != exp->ex_path.dentry))
126		return nfserr_stale;
127	return nfs_ok;
128}
129
130/*
131 * Use the given filehandle to look up the corresponding export and
132 * dentry.  On success, the results are used to set fh_export and
133 * fh_dentry.
134 */
135static __be32 nfsd_set_fh_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp)
136{
137	struct knfsd_fh	*fh = &fhp->fh_handle;
138	struct fid *fid = NULL, sfid;
139	struct svc_export *exp;
140	struct dentry *dentry;
141	int fileid_type;
142	int data_left = fh->fh_size/4;
143	__be32 error;
144
145	error = nfserr_stale;
146	if (rqstp->rq_vers > 2)
147		error = nfserr_badhandle;
148	if (rqstp->rq_vers == 4 && fh->fh_size == 0)
149		return nfserr_nofilehandle;
150
151	if (fh->fh_version == 1) {
152		int len;
153
154		if (--data_left < 0)
155			return error;
156		if (fh->fh_auth_type != 0)
157			return error;
158		len = key_len(fh->fh_fsid_type) / 4;
159		if (len == 0)
160			return error;
161		if  (fh->fh_fsid_type == FSID_MAJOR_MINOR) {
162			/* deprecated, convert to type 3 */
163			len = key_len(FSID_ENCODE_DEV)/4;
164			fh->fh_fsid_type = FSID_ENCODE_DEV;
165			/*
166			 * struct knfsd_fh uses host-endian fields, which are
167			 * sometimes used to hold net-endian values. This
168			 * confuses sparse, so we must use __force here to
169			 * keep it from complaining.
170			 */
171			fh->fh_fsid[0] = new_encode_dev(MKDEV(ntohl((__force __be32)fh->fh_fsid[0]),
172							ntohl((__force __be32)fh->fh_fsid[1])));
173			fh->fh_fsid[1] = fh->fh_fsid[2];
174		}
175		data_left -= len;
176		if (data_left < 0)
177			return error;
178		exp = rqst_exp_find(rqstp, fh->fh_fsid_type, fh->fh_fsid);
179		fid = (struct fid *)(fh->fh_fsid + len);
180	} else {
181		__u32 tfh[2];
182		dev_t xdev;
183		ino_t xino;
184
185		if (fh->fh_size != NFS_FHSIZE)
186			return error;
187		/* assume old filehandle format */
188		xdev = old_decode_dev(fh->ofh_xdev);
189		xino = u32_to_ino_t(fh->ofh_xino);
190		mk_fsid(FSID_DEV, tfh, xdev, xino, 0, NULL);
191		exp = rqst_exp_find(rqstp, FSID_DEV, tfh);
192	}
193
194	error = nfserr_stale;
195	if (PTR_ERR(exp) == -ENOENT)
196		return error;
197
198	if (IS_ERR(exp))
199		return nfserrno(PTR_ERR(exp));
200
201	if (exp->ex_flags & NFSEXP_NOSUBTREECHECK) {
202		/* Elevate privileges so that the lack of 'r' or 'x'
203		 * permission on some parent directory will
204		 * not stop exportfs_decode_fh from being able
205		 * to reconnect a directory into the dentry cache.
206		 * The same problem can affect "SUBTREECHECK" exports,
207		 * but as nfsd_acceptable depends on correct
208		 * access control settings being in effect, we cannot
209		 * fix that case easily.
210		 */
211		struct cred *new = prepare_creds();
212		if (!new) {
213			error =  nfserrno(-ENOMEM);
214			goto out;
215		}
216		new->cap_effective =
217			cap_raise_nfsd_set(new->cap_effective,
218					   new->cap_permitted);
219		put_cred(override_creds(new));
220		put_cred(new);
221	} else {
222		error = nfsd_setuser_and_check_port(rqstp, exp);
223		if (error)
224			goto out;
225	}
226
227	/*
228	 * Look up the dentry using the NFS file handle.
229	 */
230	error = nfserr_stale;
231	if (rqstp->rq_vers > 2)
232		error = nfserr_badhandle;
233
234	if (fh->fh_version != 1) {
235		sfid.i32.ino = fh->ofh_ino;
236		sfid.i32.gen = fh->ofh_generation;
237		sfid.i32.parent_ino = fh->ofh_dirino;
238		fid = &sfid;
239		data_left = 3;
240		if (fh->ofh_dirino == 0)
241			fileid_type = FILEID_INO32_GEN;
242		else
243			fileid_type = FILEID_INO32_GEN_PARENT;
244	} else
245		fileid_type = fh->fh_fileid_type;
246
247	if (fileid_type == FILEID_ROOT)
248		dentry = dget(exp->ex_path.dentry);
249	else {
250		dentry = exportfs_decode_fh(exp->ex_path.mnt, fid,
251				data_left, fileid_type,
252				nfsd_acceptable, exp);
253	}
254	if (dentry == NULL)
255		goto out;
256	if (IS_ERR(dentry)) {
257		if (PTR_ERR(dentry) != -EINVAL)
258			error = nfserrno(PTR_ERR(dentry));
259		goto out;
260	}
261
262	if (d_is_dir(dentry) &&
263			(dentry->d_flags & DCACHE_DISCONNECTED)) {
264		printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %pd2\n",
265				dentry);
266	}
267
268	fhp->fh_dentry = dentry;
269	fhp->fh_export = exp;
270	return 0;
271out:
272	exp_put(exp);
273	return error;
274}
275
276/**
277 * fh_verify - filehandle lookup and access checking
278 * @rqstp: pointer to current rpc request
279 * @fhp: filehandle to be verified
280 * @type: expected type of object pointed to by filehandle
281 * @access: type of access needed to object
282 *
283 * Look up a dentry from the on-the-wire filehandle, check the client's
284 * access to the export, and set the current task's credentials.
285 *
286 * Regardless of success or failure of fh_verify(), fh_put() should be
287 * called on @fhp when the caller is finished with the filehandle.
288 *
289 * fh_verify() may be called multiple times on a given filehandle, for
290 * example, when processing an NFSv4 compound.  The first call will look
291 * up a dentry using the on-the-wire filehandle.  Subsequent calls will
292 * skip the lookup and just perform the other checks and possibly change
293 * the current task's credentials.
294 *
295 * @type specifies the type of object expected using one of the S_IF*
296 * constants defined in include/linux/stat.h.  The caller may use zero
297 * to indicate that it doesn't care, or a negative integer to indicate
298 * that it expects something not of the given type.
299 *
300 * @access is formed from the NFSD_MAY_* constants defined in
301 * include/linux/nfsd/nfsd.h.
302 */
303__be32
304fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, int access)
305{
306	struct svc_export *exp;
307	struct dentry	*dentry;
308	__be32		error;
309
310	dprintk("nfsd: fh_verify(%s)\n", SVCFH_fmt(fhp));
311
312	if (!fhp->fh_dentry) {
313		error = nfsd_set_fh_dentry(rqstp, fhp);
314		if (error)
315			goto out;
316	}
317	dentry = fhp->fh_dentry;
318	exp = fhp->fh_export;
319	/*
320	 * We still have to do all these permission checks, even when
321	 * fh_dentry is already set:
322	 * 	- fh_verify may be called multiple times with different
323	 * 	  "access" arguments (e.g. nfsd_proc_create calls
324	 * 	  fh_verify(...,NFSD_MAY_EXEC) first, then later (in
325	 * 	  nfsd_create) calls fh_verify(...,NFSD_MAY_CREATE).
326	 *	- in the NFSv4 case, the filehandle may have been filled
327	 *	  in by fh_compose, and given a dentry, but further
328	 *	  compound operations performed with that filehandle
329	 *	  still need permissions checks.  In the worst case, a
330	 *	  mountpoint crossing may have changed the export
331	 *	  options, and we may now need to use a different uid
332	 *	  (for example, if different id-squashing options are in
333	 *	  effect on the new filesystem).
334	 */
335	error = check_pseudo_root(rqstp, dentry, exp);
336	if (error)
337		goto out;
338
339	error = nfsd_setuser_and_check_port(rqstp, exp);
340	if (error)
341		goto out;
342
343	error = nfsd_mode_check(rqstp, d_inode(dentry)->i_mode, type);
344	if (error)
345		goto out;
346
347	/*
348	 * pseudoflavor restrictions are not enforced on NLM,
349	 * which clients virtually always use auth_sys for,
350	 * even while using RPCSEC_GSS for NFS.
351	 */
352	if (access & NFSD_MAY_LOCK || access & NFSD_MAY_BYPASS_GSS)
353		goto skip_pseudoflavor_check;
354	/*
355	 * Clients may expect to be able to use auth_sys during mount,
356	 * even if they use gss for everything else; see section 2.3.2
357	 * of rfc 2623.
358	 */
359	if (access & NFSD_MAY_BYPASS_GSS_ON_ROOT
360			&& exp->ex_path.dentry == dentry)
361		goto skip_pseudoflavor_check;
362
363	error = check_nfsd_access(exp, rqstp);
364	if (error)
365		goto out;
366
367skip_pseudoflavor_check:
368	/* Finally, check access permissions. */
369	error = nfsd_permission(rqstp, exp, dentry, access);
370
371	if (error) {
372		dprintk("fh_verify: %pd2 permission failure, "
373			"acc=%x, error=%d\n",
374			dentry,
375			access, ntohl(error));
376	}
377out:
378	if (error == nfserr_stale)
379		nfsdstats.fh_stale++;
380	return error;
381}
382
383
384/*
385 * Compose a file handle for an NFS reply.
386 *
387 * Note that when first composed, the dentry may not yet have
388 * an inode.  In this case a call to fh_update should be made
389 * before the fh goes out on the wire ...
390 */
391static void _fh_update(struct svc_fh *fhp, struct svc_export *exp,
392		struct dentry *dentry)
393{
394	if (dentry != exp->ex_path.dentry) {
395		struct fid *fid = (struct fid *)
396			(fhp->fh_handle.fh_fsid + fhp->fh_handle.fh_size/4 - 1);
397		int maxsize = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
398		int subtreecheck = !(exp->ex_flags & NFSEXP_NOSUBTREECHECK);
399
400		fhp->fh_handle.fh_fileid_type =
401			exportfs_encode_fh(dentry, fid, &maxsize, subtreecheck);
402		fhp->fh_handle.fh_size += maxsize * 4;
403	} else {
404		fhp->fh_handle.fh_fileid_type = FILEID_ROOT;
405	}
406}
407
408/*
409 * for composing old style file handles
410 */
411static inline void _fh_update_old(struct dentry *dentry,
412				  struct svc_export *exp,
413				  struct knfsd_fh *fh)
414{
415	fh->ofh_ino = ino_t_to_u32(d_inode(dentry)->i_ino);
416	fh->ofh_generation = d_inode(dentry)->i_generation;
417	if (d_is_dir(dentry) ||
418	    (exp->ex_flags & NFSEXP_NOSUBTREECHECK))
419		fh->ofh_dirino = 0;
420}
421
422static bool is_root_export(struct svc_export *exp)
423{
424	return exp->ex_path.dentry == exp->ex_path.dentry->d_sb->s_root;
425}
426
427static struct super_block *exp_sb(struct svc_export *exp)
428{
429	return d_inode(exp->ex_path.dentry)->i_sb;
430}
431
432static bool fsid_type_ok_for_exp(u8 fsid_type, struct svc_export *exp)
433{
434	switch (fsid_type) {
435	case FSID_DEV:
436		if (!old_valid_dev(exp_sb(exp)->s_dev))
437			return 0;
438		/* FALL THROUGH */
439	case FSID_MAJOR_MINOR:
440	case FSID_ENCODE_DEV:
441		return exp_sb(exp)->s_type->fs_flags & FS_REQUIRES_DEV;
442	case FSID_NUM:
443		return exp->ex_flags & NFSEXP_FSID;
444	case FSID_UUID8:
445	case FSID_UUID16:
446		if (!is_root_export(exp))
447			return 0;
448		/* fall through */
449	case FSID_UUID4_INUM:
450	case FSID_UUID16_INUM:
451		return exp->ex_uuid != NULL;
452	}
453	return 1;
454}
455
456
457static void set_version_and_fsid_type(struct svc_fh *fhp, struct svc_export *exp, struct svc_fh *ref_fh)
458{
459	u8 version;
460	u8 fsid_type;
461retry:
462	version = 1;
463	if (ref_fh && ref_fh->fh_export == exp) {
464		version = ref_fh->fh_handle.fh_version;
465		fsid_type = ref_fh->fh_handle.fh_fsid_type;
466
467		ref_fh = NULL;
468
469		switch (version) {
470		case 0xca:
471			fsid_type = FSID_DEV;
472			break;
473		case 1:
474			break;
475		default:
476			goto retry;
477		}
478
479		/*
480		 * As the fsid -> filesystem mapping was guided by
481		 * user-space, there is no guarantee that the filesystem
482		 * actually supports that fsid type. If it doesn't we
483		 * loop around again without ref_fh set.
484		 */
485		if (!fsid_type_ok_for_exp(fsid_type, exp))
486			goto retry;
487	} else if (exp->ex_flags & NFSEXP_FSID) {
488		fsid_type = FSID_NUM;
489	} else if (exp->ex_uuid) {
490		if (fhp->fh_maxsize >= 64) {
491			if (is_root_export(exp))
492				fsid_type = FSID_UUID16;
493			else
494				fsid_type = FSID_UUID16_INUM;
495		} else {
496			if (is_root_export(exp))
497				fsid_type = FSID_UUID8;
498			else
499				fsid_type = FSID_UUID4_INUM;
500		}
501	} else if (!old_valid_dev(exp_sb(exp)->s_dev))
502		/* for newer device numbers, we must use a newer fsid format */
503		fsid_type = FSID_ENCODE_DEV;
504	else
505		fsid_type = FSID_DEV;
506	fhp->fh_handle.fh_version = version;
507	if (version)
508		fhp->fh_handle.fh_fsid_type = fsid_type;
509}
510
511__be32
512fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry,
513	   struct svc_fh *ref_fh)
514{
515	/* ref_fh is a reference file handle.
516	 * if it is non-null and for the same filesystem, then we should compose
517	 * a filehandle which is of the same version, where possible.
518	 * Currently, that means that if ref_fh->fh_handle.fh_version == 0xca
519	 * Then create a 32byte filehandle using nfs_fhbase_old
520	 *
521	 */
522
523	struct inode * inode = d_inode(dentry);
524	dev_t ex_dev = exp_sb(exp)->s_dev;
525
526	dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %pd2, ino=%ld)\n",
527		MAJOR(ex_dev), MINOR(ex_dev),
528		(long) d_inode(exp->ex_path.dentry)->i_ino,
529		dentry,
530		(inode ? inode->i_ino : 0));
531
532	/* Choose filehandle version and fsid type based on
533	 * the reference filehandle (if it is in the same export)
534	 * or the export options.
535	 */
536	 set_version_and_fsid_type(fhp, exp, ref_fh);
537
538	if (ref_fh == fhp)
539		fh_put(ref_fh);
540
541	if (fhp->fh_locked || fhp->fh_dentry) {
542		printk(KERN_ERR "fh_compose: fh %pd2 not initialized!\n",
543		       dentry);
544	}
545	if (fhp->fh_maxsize < NFS_FHSIZE)
546		printk(KERN_ERR "fh_compose: called with maxsize %d! %pd2\n",
547		       fhp->fh_maxsize,
548		       dentry);
549
550	fhp->fh_dentry = dget(dentry); /* our internal copy */
551	fhp->fh_export = exp_get(exp);
552
553	if (fhp->fh_handle.fh_version == 0xca) {
554		/* old style filehandle please */
555		memset(&fhp->fh_handle.fh_base, 0, NFS_FHSIZE);
556		fhp->fh_handle.fh_size = NFS_FHSIZE;
557		fhp->fh_handle.ofh_dcookie = 0xfeebbaca;
558		fhp->fh_handle.ofh_dev =  old_encode_dev(ex_dev);
559		fhp->fh_handle.ofh_xdev = fhp->fh_handle.ofh_dev;
560		fhp->fh_handle.ofh_xino =
561			ino_t_to_u32(d_inode(exp->ex_path.dentry)->i_ino);
562		fhp->fh_handle.ofh_dirino = ino_t_to_u32(parent_ino(dentry));
563		if (inode)
564			_fh_update_old(dentry, exp, &fhp->fh_handle);
565	} else {
566		fhp->fh_handle.fh_size =
567			key_len(fhp->fh_handle.fh_fsid_type) + 4;
568		fhp->fh_handle.fh_auth_type = 0;
569
570		mk_fsid(fhp->fh_handle.fh_fsid_type,
571			fhp->fh_handle.fh_fsid,
572			ex_dev,
573			d_inode(exp->ex_path.dentry)->i_ino,
574			exp->ex_fsid, exp->ex_uuid);
575
576		if (inode)
577			_fh_update(fhp, exp, dentry);
578		if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID) {
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 (d_really_is_negative(dentry))
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			return 0;
607
608		_fh_update(fhp, fhp->fh_export, dentry);
609		if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID)
610			return nfserr_opnotsupp;
611	}
612	return 0;
613out_bad:
614	printk(KERN_ERR "fh_update: fh not verified!\n");
615	return nfserr_serverfault;
616out_negative:
617	printk(KERN_ERR "fh_update: %pd2 still negative!\n",
618		dentry);
619	return nfserr_serverfault;
620}
621
622/*
623 * Release a file handle.
624 */
625void
626fh_put(struct svc_fh *fhp)
627{
628	struct dentry * dentry = fhp->fh_dentry;
629	struct svc_export * exp = fhp->fh_export;
630	if (dentry) {
631		fh_unlock(fhp);
632		fhp->fh_dentry = NULL;
633		dput(dentry);
634#ifdef CONFIG_NFSD_V3
635		fhp->fh_pre_saved = 0;
636		fhp->fh_post_saved = 0;
637#endif
638	}
639	fh_drop_write(fhp);
640	if (exp) {
641		exp_put(exp);
642		fhp->fh_export = NULL;
643	}
644	return;
645}
646
647/*
648 * Shorthand for dprintk()'s
649 */
650char * SVCFH_fmt(struct svc_fh *fhp)
651{
652	struct knfsd_fh *fh = &fhp->fh_handle;
653
654	static char buf[80];
655	sprintf(buf, "%d: %08x %08x %08x %08x %08x %08x",
656		fh->fh_size,
657		fh->fh_base.fh_pad[0],
658		fh->fh_base.fh_pad[1],
659		fh->fh_base.fh_pad[2],
660		fh->fh_base.fh_pad[3],
661		fh->fh_base.fh_pad[4],
662		fh->fh_base.fh_pad[5]);
663	return buf;
664}
665
666enum fsid_source fsid_source(struct svc_fh *fhp)
667{
668	if (fhp->fh_handle.fh_version != 1)
669		return FSIDSOURCE_DEV;
670	switch(fhp->fh_handle.fh_fsid_type) {
671	case FSID_DEV:
672	case FSID_ENCODE_DEV:
673	case FSID_MAJOR_MINOR:
674		if (exp_sb(fhp->fh_export)->s_type->fs_flags & FS_REQUIRES_DEV)
675			return FSIDSOURCE_DEV;
676		break;
677	case FSID_NUM:
678		if (fhp->fh_export->ex_flags & NFSEXP_FSID)
679			return FSIDSOURCE_FSID;
680		break;
681	default:
682		break;
683	}
684	/* either a UUID type filehandle, or the filehandle doesn't
685	 * match the export.
686	 */
687	if (fhp->fh_export->ex_flags & NFSEXP_FSID)
688		return FSIDSOURCE_FSID;
689	if (fhp->fh_export->ex_uuid)
690		return FSIDSOURCE_UUID;
691	return FSIDSOURCE_DEV;
692}
693