xref: /openbmc/linux/fs/nfsd/nfsfh.c (revision 84d517f3)
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(KERN_WARNING
92 		       "nfsd: request from insecure port %s!\n",
93 		       svc_print_addr(rqstp, buf, sizeof(buf)));
94 		return nfserr_perm;
95 	}
96 
97 	/* Set user creds for this exportpoint */
98 	return nfserrno(nfsd_setuser(rqstp, exp));
99 }
100 
101 static inline __be32 check_pseudo_root(struct svc_rqst *rqstp,
102 	struct dentry *dentry, struct svc_export *exp)
103 {
104 	if (!(exp->ex_flags & NFSEXP_V4ROOT))
105 		return nfs_ok;
106 	/*
107 	 * v2/v3 clients have no need for the V4ROOT export--they use
108 	 * the mount protocl instead; also, further V4ROOT checks may be
109 	 * in v4-specific code, in which case v2/v3 clients could bypass
110 	 * them.
111 	 */
112 	if (!nfsd_v4client(rqstp))
113 		return nfserr_stale;
114 	/*
115 	 * We're exposing only the directories and symlinks that have to be
116 	 * traversed on the way to real exports:
117 	 */
118 	if (unlikely(!S_ISDIR(dentry->d_inode->i_mode) &&
119 		     !S_ISLNK(dentry->d_inode->i_mode)))
120 		return nfserr_stale;
121 	/*
122 	 * A pseudoroot export gives permission to access only one
123 	 * single directory; the kernel has to make another upcall
124 	 * before granting access to anything else under it:
125 	 */
126 	if (unlikely(dentry != exp->ex_path.dentry))
127 		return nfserr_stale;
128 	return nfs_ok;
129 }
130 
131 /*
132  * Use the given filehandle to look up the corresponding export and
133  * dentry.  On success, the results are used to set fh_export and
134  * fh_dentry.
135  */
136 static __be32 nfsd_set_fh_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp)
137 {
138 	struct knfsd_fh	*fh = &fhp->fh_handle;
139 	struct fid *fid = NULL, sfid;
140 	struct svc_export *exp;
141 	struct dentry *dentry;
142 	int fileid_type;
143 	int data_left = fh->fh_size/4;
144 	__be32 error;
145 
146 	error = nfserr_stale;
147 	if (rqstp->rq_vers > 2)
148 		error = nfserr_badhandle;
149 	if (rqstp->rq_vers == 4 && fh->fh_size == 0)
150 		return nfserr_nofilehandle;
151 
152 	if (fh->fh_version == 1) {
153 		int len;
154 
155 		if (--data_left < 0)
156 			return error;
157 		if (fh->fh_auth_type != 0)
158 			return error;
159 		len = key_len(fh->fh_fsid_type) / 4;
160 		if (len == 0)
161 			return error;
162 		if  (fh->fh_fsid_type == FSID_MAJOR_MINOR) {
163 			/* deprecated, convert to type 3 */
164 			len = key_len(FSID_ENCODE_DEV)/4;
165 			fh->fh_fsid_type = FSID_ENCODE_DEV;
166 			fh->fh_fsid[0] = new_encode_dev(MKDEV(ntohl(fh->fh_fsid[0]), ntohl(fh->fh_fsid[1])));
167 			fh->fh_fsid[1] = fh->fh_fsid[2];
168 		}
169 		data_left -= len;
170 		if (data_left < 0)
171 			return error;
172 		exp = rqst_exp_find(rqstp, fh->fh_fsid_type, fh->fh_auth);
173 		fid = (struct fid *)(fh->fh_auth + len);
174 	} else {
175 		__u32 tfh[2];
176 		dev_t xdev;
177 		ino_t xino;
178 
179 		if (fh->fh_size != NFS_FHSIZE)
180 			return error;
181 		/* assume old filehandle format */
182 		xdev = old_decode_dev(fh->ofh_xdev);
183 		xino = u32_to_ino_t(fh->ofh_xino);
184 		mk_fsid(FSID_DEV, tfh, xdev, xino, 0, NULL);
185 		exp = rqst_exp_find(rqstp, FSID_DEV, tfh);
186 	}
187 
188 	error = nfserr_stale;
189 	if (PTR_ERR(exp) == -ENOENT)
190 		return error;
191 
192 	if (IS_ERR(exp))
193 		return nfserrno(PTR_ERR(exp));
194 
195 	if (exp->ex_flags & NFSEXP_NOSUBTREECHECK) {
196 		/* Elevate privileges so that the lack of 'r' or 'x'
197 		 * permission on some parent directory will
198 		 * not stop exportfs_decode_fh from being able
199 		 * to reconnect a directory into the dentry cache.
200 		 * The same problem can affect "SUBTREECHECK" exports,
201 		 * but as nfsd_acceptable depends on correct
202 		 * access control settings being in effect, we cannot
203 		 * fix that case easily.
204 		 */
205 		struct cred *new = prepare_creds();
206 		if (!new)
207 			return nfserrno(-ENOMEM);
208 		new->cap_effective =
209 			cap_raise_nfsd_set(new->cap_effective,
210 					   new->cap_permitted);
211 		put_cred(override_creds(new));
212 		put_cred(new);
213 	} else {
214 		error = nfsd_setuser_and_check_port(rqstp, exp);
215 		if (error)
216 			goto out;
217 	}
218 
219 	/*
220 	 * Look up the dentry using the NFS file handle.
221 	 */
222 	error = nfserr_stale;
223 	if (rqstp->rq_vers > 2)
224 		error = nfserr_badhandle;
225 
226 	if (fh->fh_version != 1) {
227 		sfid.i32.ino = fh->ofh_ino;
228 		sfid.i32.gen = fh->ofh_generation;
229 		sfid.i32.parent_ino = fh->ofh_dirino;
230 		fid = &sfid;
231 		data_left = 3;
232 		if (fh->ofh_dirino == 0)
233 			fileid_type = FILEID_INO32_GEN;
234 		else
235 			fileid_type = FILEID_INO32_GEN_PARENT;
236 	} else
237 		fileid_type = fh->fh_fileid_type;
238 
239 	if (fileid_type == FILEID_ROOT)
240 		dentry = dget(exp->ex_path.dentry);
241 	else {
242 		dentry = exportfs_decode_fh(exp->ex_path.mnt, fid,
243 				data_left, fileid_type,
244 				nfsd_acceptable, exp);
245 	}
246 	if (dentry == NULL)
247 		goto out;
248 	if (IS_ERR(dentry)) {
249 		if (PTR_ERR(dentry) != -EINVAL)
250 			error = nfserrno(PTR_ERR(dentry));
251 		goto out;
252 	}
253 
254 	if (S_ISDIR(dentry->d_inode->i_mode) &&
255 			(dentry->d_flags & DCACHE_DISCONNECTED)) {
256 		printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %pd2\n",
257 				dentry);
258 	}
259 
260 	fhp->fh_dentry = dentry;
261 	fhp->fh_export = exp;
262 	return 0;
263 out:
264 	exp_put(exp);
265 	return error;
266 }
267 
268 /**
269  * fh_verify - filehandle lookup and access checking
270  * @rqstp: pointer to current rpc request
271  * @fhp: filehandle to be verified
272  * @type: expected type of object pointed to by filehandle
273  * @access: type of access needed to object
274  *
275  * Look up a dentry from the on-the-wire filehandle, check the client's
276  * access to the export, and set the current task's credentials.
277  *
278  * Regardless of success or failure of fh_verify(), fh_put() should be
279  * called on @fhp when the caller is finished with the filehandle.
280  *
281  * fh_verify() may be called multiple times on a given filehandle, for
282  * example, when processing an NFSv4 compound.  The first call will look
283  * up a dentry using the on-the-wire filehandle.  Subsequent calls will
284  * skip the lookup and just perform the other checks and possibly change
285  * the current task's credentials.
286  *
287  * @type specifies the type of object expected using one of the S_IF*
288  * constants defined in include/linux/stat.h.  The caller may use zero
289  * to indicate that it doesn't care, or a negative integer to indicate
290  * that it expects something not of the given type.
291  *
292  * @access is formed from the NFSD_MAY_* constants defined in
293  * include/linux/nfsd/nfsd.h.
294  */
295 __be32
296 fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, int access)
297 {
298 	struct svc_export *exp;
299 	struct dentry	*dentry;
300 	__be32		error;
301 
302 	dprintk("nfsd: fh_verify(%s)\n", SVCFH_fmt(fhp));
303 
304 	if (!fhp->fh_dentry) {
305 		error = nfsd_set_fh_dentry(rqstp, fhp);
306 		if (error)
307 			goto out;
308 	}
309 	dentry = fhp->fh_dentry;
310 	exp = fhp->fh_export;
311 	/*
312 	 * We still have to do all these permission checks, even when
313 	 * fh_dentry is already set:
314 	 * 	- fh_verify may be called multiple times with different
315 	 * 	  "access" arguments (e.g. nfsd_proc_create calls
316 	 * 	  fh_verify(...,NFSD_MAY_EXEC) first, then later (in
317 	 * 	  nfsd_create) calls fh_verify(...,NFSD_MAY_CREATE).
318 	 *	- in the NFSv4 case, the filehandle may have been filled
319 	 *	  in by fh_compose, and given a dentry, but further
320 	 *	  compound operations performed with that filehandle
321 	 *	  still need permissions checks.  In the worst case, a
322 	 *	  mountpoint crossing may have changed the export
323 	 *	  options, and we may now need to use a different uid
324 	 *	  (for example, if different id-squashing options are in
325 	 *	  effect on the new filesystem).
326 	 */
327 	error = check_pseudo_root(rqstp, dentry, exp);
328 	if (error)
329 		goto out;
330 
331 	error = nfsd_setuser_and_check_port(rqstp, exp);
332 	if (error)
333 		goto out;
334 
335 	error = nfsd_mode_check(rqstp, dentry->d_inode->i_mode, type);
336 	if (error)
337 		goto out;
338 
339 	/*
340 	 * pseudoflavor restrictions are not enforced on NLM,
341 	 * which clients virtually always use auth_sys for,
342 	 * even while using RPCSEC_GSS for NFS.
343 	 */
344 	if (access & NFSD_MAY_LOCK || access & NFSD_MAY_BYPASS_GSS)
345 		goto skip_pseudoflavor_check;
346 	/*
347 	 * Clients may expect to be able to use auth_sys during mount,
348 	 * even if they use gss for everything else; see section 2.3.2
349 	 * of rfc 2623.
350 	 */
351 	if (access & NFSD_MAY_BYPASS_GSS_ON_ROOT
352 			&& exp->ex_path.dentry == dentry)
353 		goto skip_pseudoflavor_check;
354 
355 	error = check_nfsd_access(exp, rqstp);
356 	if (error)
357 		goto out;
358 
359 skip_pseudoflavor_check:
360 	/* Finally, check access permissions. */
361 	error = nfsd_permission(rqstp, exp, dentry, access);
362 
363 	if (error) {
364 		dprintk("fh_verify: %pd2 permission failure, "
365 			"acc=%x, error=%d\n",
366 			dentry,
367 			access, ntohl(error));
368 	}
369 out:
370 	if (error == nfserr_stale)
371 		nfsdstats.fh_stale++;
372 	return error;
373 }
374 
375 
376 /*
377  * Compose a file handle for an NFS reply.
378  *
379  * Note that when first composed, the dentry may not yet have
380  * an inode.  In this case a call to fh_update should be made
381  * before the fh goes out on the wire ...
382  */
383 static void _fh_update(struct svc_fh *fhp, struct svc_export *exp,
384 		struct dentry *dentry)
385 {
386 	if (dentry != exp->ex_path.dentry) {
387 		struct fid *fid = (struct fid *)
388 			(fhp->fh_handle.fh_auth + fhp->fh_handle.fh_size/4 - 1);
389 		int maxsize = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
390 		int subtreecheck = !(exp->ex_flags & NFSEXP_NOSUBTREECHECK);
391 
392 		fhp->fh_handle.fh_fileid_type =
393 			exportfs_encode_fh(dentry, fid, &maxsize, subtreecheck);
394 		fhp->fh_handle.fh_size += maxsize * 4;
395 	} else {
396 		fhp->fh_handle.fh_fileid_type = FILEID_ROOT;
397 	}
398 }
399 
400 /*
401  * for composing old style file handles
402  */
403 static inline void _fh_update_old(struct dentry *dentry,
404 				  struct svc_export *exp,
405 				  struct knfsd_fh *fh)
406 {
407 	fh->ofh_ino = ino_t_to_u32(dentry->d_inode->i_ino);
408 	fh->ofh_generation = dentry->d_inode->i_generation;
409 	if (S_ISDIR(dentry->d_inode->i_mode) ||
410 	    (exp->ex_flags & NFSEXP_NOSUBTREECHECK))
411 		fh->ofh_dirino = 0;
412 }
413 
414 static bool is_root_export(struct svc_export *exp)
415 {
416 	return exp->ex_path.dentry == exp->ex_path.dentry->d_sb->s_root;
417 }
418 
419 static struct super_block *exp_sb(struct svc_export *exp)
420 {
421 	return exp->ex_path.dentry->d_inode->i_sb;
422 }
423 
424 static bool fsid_type_ok_for_exp(u8 fsid_type, struct svc_export *exp)
425 {
426 	switch (fsid_type) {
427 	case FSID_DEV:
428 		if (!old_valid_dev(exp_sb(exp)->s_dev))
429 			return 0;
430 		/* FALL THROUGH */
431 	case FSID_MAJOR_MINOR:
432 	case FSID_ENCODE_DEV:
433 		return exp_sb(exp)->s_type->fs_flags & FS_REQUIRES_DEV;
434 	case FSID_NUM:
435 		return exp->ex_flags & NFSEXP_FSID;
436 	case FSID_UUID8:
437 	case FSID_UUID16:
438 		if (!is_root_export(exp))
439 			return 0;
440 		/* fall through */
441 	case FSID_UUID4_INUM:
442 	case FSID_UUID16_INUM:
443 		return exp->ex_uuid != NULL;
444 	}
445 	return 1;
446 }
447 
448 
449 static void set_version_and_fsid_type(struct svc_fh *fhp, struct svc_export *exp, struct svc_fh *ref_fh)
450 {
451 	u8 version;
452 	u8 fsid_type;
453 retry:
454 	version = 1;
455 	if (ref_fh && ref_fh->fh_export == exp) {
456 		version = ref_fh->fh_handle.fh_version;
457 		fsid_type = ref_fh->fh_handle.fh_fsid_type;
458 
459 		ref_fh = NULL;
460 
461 		switch (version) {
462 		case 0xca:
463 			fsid_type = FSID_DEV;
464 			break;
465 		case 1:
466 			break;
467 		default:
468 			goto retry;
469 		}
470 
471 		/*
472 		 * As the fsid -> filesystem mapping was guided by
473 		 * user-space, there is no guarantee that the filesystem
474 		 * actually supports that fsid type. If it doesn't we
475 		 * loop around again without ref_fh set.
476 		 */
477 		if (!fsid_type_ok_for_exp(fsid_type, exp))
478 			goto retry;
479 	} else if (exp->ex_flags & NFSEXP_FSID) {
480 		fsid_type = FSID_NUM;
481 	} else if (exp->ex_uuid) {
482 		if (fhp->fh_maxsize >= 64) {
483 			if (is_root_export(exp))
484 				fsid_type = FSID_UUID16;
485 			else
486 				fsid_type = FSID_UUID16_INUM;
487 		} else {
488 			if (is_root_export(exp))
489 				fsid_type = FSID_UUID8;
490 			else
491 				fsid_type = FSID_UUID4_INUM;
492 		}
493 	} else if (!old_valid_dev(exp_sb(exp)->s_dev))
494 		/* for newer device numbers, we must use a newer fsid format */
495 		fsid_type = FSID_ENCODE_DEV;
496 	else
497 		fsid_type = FSID_DEV;
498 	fhp->fh_handle.fh_version = version;
499 	if (version)
500 		fhp->fh_handle.fh_fsid_type = fsid_type;
501 }
502 
503 __be32
504 fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry,
505 	   struct svc_fh *ref_fh)
506 {
507 	/* ref_fh is a reference file handle.
508 	 * if it is non-null and for the same filesystem, then we should compose
509 	 * a filehandle which is of the same version, where possible.
510 	 * Currently, that means that if ref_fh->fh_handle.fh_version == 0xca
511 	 * Then create a 32byte filehandle using nfs_fhbase_old
512 	 *
513 	 */
514 
515 	struct inode * inode = dentry->d_inode;
516 	__u32 *datap;
517 	dev_t ex_dev = exp_sb(exp)->s_dev;
518 
519 	dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %pd2, ino=%ld)\n",
520 		MAJOR(ex_dev), MINOR(ex_dev),
521 		(long) exp->ex_path.dentry->d_inode->i_ino,
522 		dentry,
523 		(inode ? inode->i_ino : 0));
524 
525 	/* Choose filehandle version and fsid type based on
526 	 * the reference filehandle (if it is in the same export)
527 	 * or the export options.
528 	 */
529 	 set_version_and_fsid_type(fhp, exp, ref_fh);
530 
531 	if (ref_fh == fhp)
532 		fh_put(ref_fh);
533 
534 	if (fhp->fh_locked || fhp->fh_dentry) {
535 		printk(KERN_ERR "fh_compose: fh %pd2 not initialized!\n",
536 		       dentry);
537 	}
538 	if (fhp->fh_maxsize < NFS_FHSIZE)
539 		printk(KERN_ERR "fh_compose: called with maxsize %d! %pd2\n",
540 		       fhp->fh_maxsize,
541 		       dentry);
542 
543 	fhp->fh_dentry = dget(dentry); /* our internal copy */
544 	fhp->fh_export = exp;
545 	cache_get(&exp->h);
546 
547 	if (fhp->fh_handle.fh_version == 0xca) {
548 		/* old style filehandle please */
549 		memset(&fhp->fh_handle.fh_base, 0, NFS_FHSIZE);
550 		fhp->fh_handle.fh_size = NFS_FHSIZE;
551 		fhp->fh_handle.ofh_dcookie = 0xfeebbaca;
552 		fhp->fh_handle.ofh_dev =  old_encode_dev(ex_dev);
553 		fhp->fh_handle.ofh_xdev = fhp->fh_handle.ofh_dev;
554 		fhp->fh_handle.ofh_xino =
555 			ino_t_to_u32(exp->ex_path.dentry->d_inode->i_ino);
556 		fhp->fh_handle.ofh_dirino = ino_t_to_u32(parent_ino(dentry));
557 		if (inode)
558 			_fh_update_old(dentry, exp, &fhp->fh_handle);
559 	} else {
560 		int len;
561 		fhp->fh_handle.fh_auth_type = 0;
562 		datap = fhp->fh_handle.fh_auth+0;
563 		mk_fsid(fhp->fh_handle.fh_fsid_type, datap, ex_dev,
564 			exp->ex_path.dentry->d_inode->i_ino,
565 			exp->ex_fsid, exp->ex_uuid);
566 
567 		len = key_len(fhp->fh_handle.fh_fsid_type);
568 		datap += len/4;
569 		fhp->fh_handle.fh_size = 4 + len;
570 
571 		if (inode)
572 			_fh_update(fhp, exp, dentry);
573 		if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID) {
574 			fh_put(fhp);
575 			return nfserr_opnotsupp;
576 		}
577 	}
578 
579 	return 0;
580 }
581 
582 /*
583  * Update file handle information after changing a dentry.
584  * This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create
585  */
586 __be32
587 fh_update(struct svc_fh *fhp)
588 {
589 	struct dentry *dentry;
590 
591 	if (!fhp->fh_dentry)
592 		goto out_bad;
593 
594 	dentry = fhp->fh_dentry;
595 	if (!dentry->d_inode)
596 		goto out_negative;
597 	if (fhp->fh_handle.fh_version != 1) {
598 		_fh_update_old(dentry, fhp->fh_export, &fhp->fh_handle);
599 	} else {
600 		if (fhp->fh_handle.fh_fileid_type != FILEID_ROOT)
601 			return 0;
602 
603 		_fh_update(fhp, fhp->fh_export, dentry);
604 		if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID)
605 			return nfserr_opnotsupp;
606 	}
607 	return 0;
608 out_bad:
609 	printk(KERN_ERR "fh_update: fh not verified!\n");
610 	return nfserr_serverfault;
611 out_negative:
612 	printk(KERN_ERR "fh_update: %pd2 still negative!\n",
613 		dentry);
614 	return nfserr_serverfault;
615 }
616 
617 /*
618  * Release a file handle.
619  */
620 void
621 fh_put(struct svc_fh *fhp)
622 {
623 	struct dentry * dentry = fhp->fh_dentry;
624 	struct svc_export * exp = fhp->fh_export;
625 	if (dentry) {
626 		fh_unlock(fhp);
627 		fhp->fh_dentry = NULL;
628 		dput(dentry);
629 #ifdef CONFIG_NFSD_V3
630 		fhp->fh_pre_saved = 0;
631 		fhp->fh_post_saved = 0;
632 #endif
633 	}
634 	fh_drop_write(fhp);
635 	if (exp) {
636 		exp_put(exp);
637 		fhp->fh_export = NULL;
638 	}
639 	return;
640 }
641 
642 /*
643  * Shorthand for dprintk()'s
644  */
645 char * SVCFH_fmt(struct svc_fh *fhp)
646 {
647 	struct knfsd_fh *fh = &fhp->fh_handle;
648 
649 	static char buf[80];
650 	sprintf(buf, "%d: %08x %08x %08x %08x %08x %08x",
651 		fh->fh_size,
652 		fh->fh_base.fh_pad[0],
653 		fh->fh_base.fh_pad[1],
654 		fh->fh_base.fh_pad[2],
655 		fh->fh_base.fh_pad[3],
656 		fh->fh_base.fh_pad[4],
657 		fh->fh_base.fh_pad[5]);
658 	return buf;
659 }
660 
661 enum fsid_source fsid_source(struct svc_fh *fhp)
662 {
663 	if (fhp->fh_handle.fh_version != 1)
664 		return FSIDSOURCE_DEV;
665 	switch(fhp->fh_handle.fh_fsid_type) {
666 	case FSID_DEV:
667 	case FSID_ENCODE_DEV:
668 	case FSID_MAJOR_MINOR:
669 		if (exp_sb(fhp->fh_export)->s_type->fs_flags & FS_REQUIRES_DEV)
670 			return FSIDSOURCE_DEV;
671 		break;
672 	case FSID_NUM:
673 		if (fhp->fh_export->ex_flags & NFSEXP_FSID)
674 			return FSIDSOURCE_FSID;
675 		break;
676 	default:
677 		break;
678 	}
679 	/* either a UUID type filehandle, or the filehandle doesn't
680 	 * match the export.
681 	 */
682 	if (fhp->fh_export->ex_flags & NFSEXP_FSID)
683 		return FSIDSOURCE_FSID;
684 	if (fhp->fh_export->ex_uuid)
685 		return FSIDSOURCE_UUID;
686 	return FSIDSOURCE_DEV;
687 }
688