xref: /openbmc/linux/fs/nfsd/nfsfh.c (revision 3932b9ca)
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  */
26 static 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 %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  */
61 static inline __be32
62 nfsd_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 
83 static __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 (!rqstp->rq_secure && !(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 
100 static 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(!S_ISDIR(dentry->d_inode->i_mode) &&
118 		     !S_ISLNK(dentry->d_inode->i_mode)))
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  */
135 static __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 			return nfserrno(-ENOMEM);
214 		new->cap_effective =
215 			cap_raise_nfsd_set(new->cap_effective,
216 					   new->cap_permitted);
217 		put_cred(override_creds(new));
218 		put_cred(new);
219 	} else {
220 		error = nfsd_setuser_and_check_port(rqstp, exp);
221 		if (error)
222 			goto out;
223 	}
224 
225 	/*
226 	 * Look up the dentry using the NFS file handle.
227 	 */
228 	error = nfserr_stale;
229 	if (rqstp->rq_vers > 2)
230 		error = nfserr_badhandle;
231 
232 	if (fh->fh_version != 1) {
233 		sfid.i32.ino = fh->ofh_ino;
234 		sfid.i32.gen = fh->ofh_generation;
235 		sfid.i32.parent_ino = fh->ofh_dirino;
236 		fid = &sfid;
237 		data_left = 3;
238 		if (fh->ofh_dirino == 0)
239 			fileid_type = FILEID_INO32_GEN;
240 		else
241 			fileid_type = FILEID_INO32_GEN_PARENT;
242 	} else
243 		fileid_type = fh->fh_fileid_type;
244 
245 	if (fileid_type == FILEID_ROOT)
246 		dentry = dget(exp->ex_path.dentry);
247 	else {
248 		dentry = exportfs_decode_fh(exp->ex_path.mnt, fid,
249 				data_left, fileid_type,
250 				nfsd_acceptable, exp);
251 	}
252 	if (dentry == NULL)
253 		goto out;
254 	if (IS_ERR(dentry)) {
255 		if (PTR_ERR(dentry) != -EINVAL)
256 			error = nfserrno(PTR_ERR(dentry));
257 		goto out;
258 	}
259 
260 	if (S_ISDIR(dentry->d_inode->i_mode) &&
261 			(dentry->d_flags & DCACHE_DISCONNECTED)) {
262 		printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %pd2\n",
263 				dentry);
264 	}
265 
266 	fhp->fh_dentry = dentry;
267 	fhp->fh_export = exp;
268 	return 0;
269 out:
270 	exp_put(exp);
271 	return error;
272 }
273 
274 /**
275  * fh_verify - filehandle lookup and access checking
276  * @rqstp: pointer to current rpc request
277  * @fhp: filehandle to be verified
278  * @type: expected type of object pointed to by filehandle
279  * @access: type of access needed to object
280  *
281  * Look up a dentry from the on-the-wire filehandle, check the client's
282  * access to the export, and set the current task's credentials.
283  *
284  * Regardless of success or failure of fh_verify(), fh_put() should be
285  * called on @fhp when the caller is finished with the filehandle.
286  *
287  * fh_verify() may be called multiple times on a given filehandle, for
288  * example, when processing an NFSv4 compound.  The first call will look
289  * up a dentry using the on-the-wire filehandle.  Subsequent calls will
290  * skip the lookup and just perform the other checks and possibly change
291  * the current task's credentials.
292  *
293  * @type specifies the type of object expected using one of the S_IF*
294  * constants defined in include/linux/stat.h.  The caller may use zero
295  * to indicate that it doesn't care, or a negative integer to indicate
296  * that it expects something not of the given type.
297  *
298  * @access is formed from the NFSD_MAY_* constants defined in
299  * include/linux/nfsd/nfsd.h.
300  */
301 __be32
302 fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, int access)
303 {
304 	struct svc_export *exp;
305 	struct dentry	*dentry;
306 	__be32		error;
307 
308 	dprintk("nfsd: fh_verify(%s)\n", SVCFH_fmt(fhp));
309 
310 	if (!fhp->fh_dentry) {
311 		error = nfsd_set_fh_dentry(rqstp, fhp);
312 		if (error)
313 			goto out;
314 	}
315 	dentry = fhp->fh_dentry;
316 	exp = fhp->fh_export;
317 	/*
318 	 * We still have to do all these permission checks, even when
319 	 * fh_dentry is already set:
320 	 * 	- fh_verify may be called multiple times with different
321 	 * 	  "access" arguments (e.g. nfsd_proc_create calls
322 	 * 	  fh_verify(...,NFSD_MAY_EXEC) first, then later (in
323 	 * 	  nfsd_create) calls fh_verify(...,NFSD_MAY_CREATE).
324 	 *	- in the NFSv4 case, the filehandle may have been filled
325 	 *	  in by fh_compose, and given a dentry, but further
326 	 *	  compound operations performed with that filehandle
327 	 *	  still need permissions checks.  In the worst case, a
328 	 *	  mountpoint crossing may have changed the export
329 	 *	  options, and we may now need to use a different uid
330 	 *	  (for example, if different id-squashing options are in
331 	 *	  effect on the new filesystem).
332 	 */
333 	error = check_pseudo_root(rqstp, dentry, exp);
334 	if (error)
335 		goto out;
336 
337 	error = nfsd_setuser_and_check_port(rqstp, exp);
338 	if (error)
339 		goto out;
340 
341 	error = nfsd_mode_check(rqstp, dentry->d_inode->i_mode, type);
342 	if (error)
343 		goto out;
344 
345 	/*
346 	 * pseudoflavor restrictions are not enforced on NLM,
347 	 * which clients virtually always use auth_sys for,
348 	 * even while using RPCSEC_GSS for NFS.
349 	 */
350 	if (access & NFSD_MAY_LOCK || access & NFSD_MAY_BYPASS_GSS)
351 		goto skip_pseudoflavor_check;
352 	/*
353 	 * Clients may expect to be able to use auth_sys during mount,
354 	 * even if they use gss for everything else; see section 2.3.2
355 	 * of rfc 2623.
356 	 */
357 	if (access & NFSD_MAY_BYPASS_GSS_ON_ROOT
358 			&& exp->ex_path.dentry == dentry)
359 		goto skip_pseudoflavor_check;
360 
361 	error = check_nfsd_access(exp, rqstp);
362 	if (error)
363 		goto out;
364 
365 skip_pseudoflavor_check:
366 	/* Finally, check access permissions. */
367 	error = nfsd_permission(rqstp, exp, dentry, access);
368 
369 	if (error) {
370 		dprintk("fh_verify: %pd2 permission failure, "
371 			"acc=%x, error=%d\n",
372 			dentry,
373 			access, ntohl(error));
374 	}
375 out:
376 	if (error == nfserr_stale)
377 		nfsdstats.fh_stale++;
378 	return error;
379 }
380 
381 
382 /*
383  * Compose a file handle for an NFS reply.
384  *
385  * Note that when first composed, the dentry may not yet have
386  * an inode.  In this case a call to fh_update should be made
387  * before the fh goes out on the wire ...
388  */
389 static void _fh_update(struct svc_fh *fhp, struct svc_export *exp,
390 		struct dentry *dentry)
391 {
392 	if (dentry != exp->ex_path.dentry) {
393 		struct fid *fid = (struct fid *)
394 			(fhp->fh_handle.fh_fsid + fhp->fh_handle.fh_size/4 - 1);
395 		int maxsize = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
396 		int subtreecheck = !(exp->ex_flags & NFSEXP_NOSUBTREECHECK);
397 
398 		fhp->fh_handle.fh_fileid_type =
399 			exportfs_encode_fh(dentry, fid, &maxsize, subtreecheck);
400 		fhp->fh_handle.fh_size += maxsize * 4;
401 	} else {
402 		fhp->fh_handle.fh_fileid_type = FILEID_ROOT;
403 	}
404 }
405 
406 /*
407  * for composing old style file handles
408  */
409 static inline void _fh_update_old(struct dentry *dentry,
410 				  struct svc_export *exp,
411 				  struct knfsd_fh *fh)
412 {
413 	fh->ofh_ino = ino_t_to_u32(dentry->d_inode->i_ino);
414 	fh->ofh_generation = dentry->d_inode->i_generation;
415 	if (S_ISDIR(dentry->d_inode->i_mode) ||
416 	    (exp->ex_flags & NFSEXP_NOSUBTREECHECK))
417 		fh->ofh_dirino = 0;
418 }
419 
420 static bool is_root_export(struct svc_export *exp)
421 {
422 	return exp->ex_path.dentry == exp->ex_path.dentry->d_sb->s_root;
423 }
424 
425 static struct super_block *exp_sb(struct svc_export *exp)
426 {
427 	return exp->ex_path.dentry->d_inode->i_sb;
428 }
429 
430 static bool fsid_type_ok_for_exp(u8 fsid_type, struct svc_export *exp)
431 {
432 	switch (fsid_type) {
433 	case FSID_DEV:
434 		if (!old_valid_dev(exp_sb(exp)->s_dev))
435 			return 0;
436 		/* FALL THROUGH */
437 	case FSID_MAJOR_MINOR:
438 	case FSID_ENCODE_DEV:
439 		return exp_sb(exp)->s_type->fs_flags & FS_REQUIRES_DEV;
440 	case FSID_NUM:
441 		return exp->ex_flags & NFSEXP_FSID;
442 	case FSID_UUID8:
443 	case FSID_UUID16:
444 		if (!is_root_export(exp))
445 			return 0;
446 		/* fall through */
447 	case FSID_UUID4_INUM:
448 	case FSID_UUID16_INUM:
449 		return exp->ex_uuid != NULL;
450 	}
451 	return 1;
452 }
453 
454 
455 static void set_version_and_fsid_type(struct svc_fh *fhp, struct svc_export *exp, struct svc_fh *ref_fh)
456 {
457 	u8 version;
458 	u8 fsid_type;
459 retry:
460 	version = 1;
461 	if (ref_fh && ref_fh->fh_export == exp) {
462 		version = ref_fh->fh_handle.fh_version;
463 		fsid_type = ref_fh->fh_handle.fh_fsid_type;
464 
465 		ref_fh = NULL;
466 
467 		switch (version) {
468 		case 0xca:
469 			fsid_type = FSID_DEV;
470 			break;
471 		case 1:
472 			break;
473 		default:
474 			goto retry;
475 		}
476 
477 		/*
478 		 * As the fsid -> filesystem mapping was guided by
479 		 * user-space, there is no guarantee that the filesystem
480 		 * actually supports that fsid type. If it doesn't we
481 		 * loop around again without ref_fh set.
482 		 */
483 		if (!fsid_type_ok_for_exp(fsid_type, exp))
484 			goto retry;
485 	} else if (exp->ex_flags & NFSEXP_FSID) {
486 		fsid_type = FSID_NUM;
487 	} else if (exp->ex_uuid) {
488 		if (fhp->fh_maxsize >= 64) {
489 			if (is_root_export(exp))
490 				fsid_type = FSID_UUID16;
491 			else
492 				fsid_type = FSID_UUID16_INUM;
493 		} else {
494 			if (is_root_export(exp))
495 				fsid_type = FSID_UUID8;
496 			else
497 				fsid_type = FSID_UUID4_INUM;
498 		}
499 	} else if (!old_valid_dev(exp_sb(exp)->s_dev))
500 		/* for newer device numbers, we must use a newer fsid format */
501 		fsid_type = FSID_ENCODE_DEV;
502 	else
503 		fsid_type = FSID_DEV;
504 	fhp->fh_handle.fh_version = version;
505 	if (version)
506 		fhp->fh_handle.fh_fsid_type = fsid_type;
507 }
508 
509 __be32
510 fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry,
511 	   struct svc_fh *ref_fh)
512 {
513 	/* ref_fh is a reference file handle.
514 	 * if it is non-null and for the same filesystem, then we should compose
515 	 * a filehandle which is of the same version, where possible.
516 	 * Currently, that means that if ref_fh->fh_handle.fh_version == 0xca
517 	 * Then create a 32byte filehandle using nfs_fhbase_old
518 	 *
519 	 */
520 
521 	struct inode * inode = dentry->d_inode;
522 	dev_t ex_dev = exp_sb(exp)->s_dev;
523 
524 	dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %pd2, ino=%ld)\n",
525 		MAJOR(ex_dev), MINOR(ex_dev),
526 		(long) exp->ex_path.dentry->d_inode->i_ino,
527 		dentry,
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 %pd2 not initialized!\n",
541 		       dentry);
542 	}
543 	if (fhp->fh_maxsize < NFS_FHSIZE)
544 		printk(KERN_ERR "fh_compose: called with maxsize %d! %pd2\n",
545 		       fhp->fh_maxsize,
546 		       dentry);
547 
548 	fhp->fh_dentry = dget(dentry); /* our internal copy */
549 	fhp->fh_export = exp_get(exp);
550 
551 	if (fhp->fh_handle.fh_version == 0xca) {
552 		/* old style filehandle please */
553 		memset(&fhp->fh_handle.fh_base, 0, NFS_FHSIZE);
554 		fhp->fh_handle.fh_size = NFS_FHSIZE;
555 		fhp->fh_handle.ofh_dcookie = 0xfeebbaca;
556 		fhp->fh_handle.ofh_dev =  old_encode_dev(ex_dev);
557 		fhp->fh_handle.ofh_xdev = fhp->fh_handle.ofh_dev;
558 		fhp->fh_handle.ofh_xino =
559 			ino_t_to_u32(exp->ex_path.dentry->d_inode->i_ino);
560 		fhp->fh_handle.ofh_dirino = ino_t_to_u32(parent_ino(dentry));
561 		if (inode)
562 			_fh_update_old(dentry, exp, &fhp->fh_handle);
563 	} else {
564 		fhp->fh_handle.fh_size =
565 			key_len(fhp->fh_handle.fh_fsid_type) + 4;
566 		fhp->fh_handle.fh_auth_type = 0;
567 
568 		mk_fsid(fhp->fh_handle.fh_fsid_type,
569 			fhp->fh_handle.fh_fsid,
570 			ex_dev,
571 			exp->ex_path.dentry->d_inode->i_ino,
572 			exp->ex_fsid, exp->ex_uuid);
573 
574 		if (inode)
575 			_fh_update(fhp, exp, dentry);
576 		if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID) {
577 			fh_put(fhp);
578 			return nfserr_opnotsupp;
579 		}
580 	}
581 
582 	return 0;
583 }
584 
585 /*
586  * Update file handle information after changing a dentry.
587  * This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create
588  */
589 __be32
590 fh_update(struct svc_fh *fhp)
591 {
592 	struct dentry *dentry;
593 
594 	if (!fhp->fh_dentry)
595 		goto out_bad;
596 
597 	dentry = fhp->fh_dentry;
598 	if (!dentry->d_inode)
599 		goto out_negative;
600 	if (fhp->fh_handle.fh_version != 1) {
601 		_fh_update_old(dentry, fhp->fh_export, &fhp->fh_handle);
602 	} else {
603 		if (fhp->fh_handle.fh_fileid_type != FILEID_ROOT)
604 			return 0;
605 
606 		_fh_update(fhp, fhp->fh_export, dentry);
607 		if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID)
608 			return nfserr_opnotsupp;
609 	}
610 	return 0;
611 out_bad:
612 	printk(KERN_ERR "fh_update: fh not verified!\n");
613 	return nfserr_serverfault;
614 out_negative:
615 	printk(KERN_ERR "fh_update: %pd2 still negative!\n",
616 		dentry);
617 	return nfserr_serverfault;
618 }
619 
620 /*
621  * Release a file handle.
622  */
623 void
624 fh_put(struct svc_fh *fhp)
625 {
626 	struct dentry * dentry = fhp->fh_dentry;
627 	struct svc_export * exp = fhp->fh_export;
628 	if (dentry) {
629 		fh_unlock(fhp);
630 		fhp->fh_dentry = NULL;
631 		dput(dentry);
632 #ifdef CONFIG_NFSD_V3
633 		fhp->fh_pre_saved = 0;
634 		fhp->fh_post_saved = 0;
635 #endif
636 	}
637 	fh_drop_write(fhp);
638 	if (exp) {
639 		exp_put(exp);
640 		fhp->fh_export = NULL;
641 	}
642 	return;
643 }
644 
645 /*
646  * Shorthand for dprintk()'s
647  */
648 char * SVCFH_fmt(struct svc_fh *fhp)
649 {
650 	struct knfsd_fh *fh = &fhp->fh_handle;
651 
652 	static char buf[80];
653 	sprintf(buf, "%d: %08x %08x %08x %08x %08x %08x",
654 		fh->fh_size,
655 		fh->fh_base.fh_pad[0],
656 		fh->fh_base.fh_pad[1],
657 		fh->fh_base.fh_pad[2],
658 		fh->fh_base.fh_pad[3],
659 		fh->fh_base.fh_pad[4],
660 		fh->fh_base.fh_pad[5]);
661 	return buf;
662 }
663 
664 enum fsid_source fsid_source(struct svc_fh *fhp)
665 {
666 	if (fhp->fh_handle.fh_version != 1)
667 		return FSIDSOURCE_DEV;
668 	switch(fhp->fh_handle.fh_fsid_type) {
669 	case FSID_DEV:
670 	case FSID_ENCODE_DEV:
671 	case FSID_MAJOR_MINOR:
672 		if (exp_sb(fhp->fh_export)->s_type->fs_flags & FS_REQUIRES_DEV)
673 			return FSIDSOURCE_DEV;
674 		break;
675 	case FSID_NUM:
676 		if (fhp->fh_export->ex_flags & NFSEXP_FSID)
677 			return FSIDSOURCE_FSID;
678 		break;
679 	default:
680 		break;
681 	}
682 	/* either a UUID type filehandle, or the filehandle doesn't
683 	 * match the export.
684 	 */
685 	if (fhp->fh_export->ex_flags & NFSEXP_FSID)
686 		return FSIDSOURCE_FSID;
687 	if (fhp->fh_export->ex_uuid)
688 		return FSIDSOURCE_UUID;
689 	return FSIDSOURCE_DEV;
690 }
691