xref: /openbmc/linux/fs/nfsd/nfsfh.c (revision 4beec1d7)
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(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  */
61 static inline __be32
62 nfsd_mode_check(struct svc_rqst *rqstp, struct dentry *dentry,
63 		umode_t requested)
64 {
65 	umode_t mode = d_inode(dentry)->i_mode & S_IFMT;
66 
67 	if (requested == 0) /* the caller doesn't care */
68 		return nfs_ok;
69 	if (mode == requested) {
70 		if (mode == S_IFDIR && !d_can_lookup(dentry)) {
71 			WARN_ON_ONCE(1);
72 			return nfserr_notdir;
73 		}
74 		return nfs_ok;
75 	}
76 	/*
77 	 * v4 has an error more specific than err_notdir which we should
78 	 * return in preference to err_notdir:
79 	 */
80 	if (rqstp->rq_vers == 4 && mode == S_IFLNK)
81 		return nfserr_symlink;
82 	if (requested == S_IFDIR)
83 		return nfserr_notdir;
84 	if (mode == S_IFDIR)
85 		return nfserr_isdir;
86 	return nfserr_inval;
87 }
88 
89 static __be32 nfsd_setuser_and_check_port(struct svc_rqst *rqstp,
90 					  struct svc_export *exp)
91 {
92 	int flags = nfsexp_flags(rqstp, exp);
93 
94 	/* Check if the request originated from a secure port. */
95 	if (!test_bit(RQ_SECURE, &rqstp->rq_flags) && !(flags & NFSEXP_INSECURE_PORT)) {
96 		RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
97 		dprintk("nfsd: request from insecure port %s!\n",
98 		        svc_print_addr(rqstp, buf, sizeof(buf)));
99 		return nfserr_perm;
100 	}
101 
102 	/* Set user creds for this exportpoint */
103 	return nfserrno(nfsd_setuser(rqstp, exp));
104 }
105 
106 static inline __be32 check_pseudo_root(struct svc_rqst *rqstp,
107 	struct dentry *dentry, struct svc_export *exp)
108 {
109 	if (!(exp->ex_flags & NFSEXP_V4ROOT))
110 		return nfs_ok;
111 	/*
112 	 * v2/v3 clients have no need for the V4ROOT export--they use
113 	 * the mount protocl instead; also, further V4ROOT checks may be
114 	 * in v4-specific code, in which case v2/v3 clients could bypass
115 	 * them.
116 	 */
117 	if (!nfsd_v4client(rqstp))
118 		return nfserr_stale;
119 	/*
120 	 * We're exposing only the directories and symlinks that have to be
121 	 * traversed on the way to real exports:
122 	 */
123 	if (unlikely(!d_is_dir(dentry) &&
124 		     !d_is_symlink(dentry)))
125 		return nfserr_stale;
126 	/*
127 	 * A pseudoroot export gives permission to access only one
128 	 * single directory; the kernel has to make another upcall
129 	 * before granting access to anything else under it:
130 	 */
131 	if (unlikely(dentry != exp->ex_path.dentry))
132 		return nfserr_stale;
133 	return nfs_ok;
134 }
135 
136 /*
137  * Use the given filehandle to look up the corresponding export and
138  * dentry.  On success, the results are used to set fh_export and
139  * fh_dentry.
140  */
141 static __be32 nfsd_set_fh_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp)
142 {
143 	struct knfsd_fh	*fh = &fhp->fh_handle;
144 	struct fid *fid = NULL, sfid;
145 	struct svc_export *exp;
146 	struct dentry *dentry;
147 	int fileid_type;
148 	int data_left = fh->fh_size/4;
149 	__be32 error;
150 
151 	error = nfserr_stale;
152 	if (rqstp->rq_vers > 2)
153 		error = nfserr_badhandle;
154 	if (rqstp->rq_vers == 4 && fh->fh_size == 0)
155 		return nfserr_nofilehandle;
156 
157 	if (fh->fh_version == 1) {
158 		int len;
159 
160 		if (--data_left < 0)
161 			return error;
162 		if (fh->fh_auth_type != 0)
163 			return error;
164 		len = key_len(fh->fh_fsid_type) / 4;
165 		if (len == 0)
166 			return error;
167 		if  (fh->fh_fsid_type == FSID_MAJOR_MINOR) {
168 			/* deprecated, convert to type 3 */
169 			len = key_len(FSID_ENCODE_DEV)/4;
170 			fh->fh_fsid_type = FSID_ENCODE_DEV;
171 			/*
172 			 * struct knfsd_fh uses host-endian fields, which are
173 			 * sometimes used to hold net-endian values. This
174 			 * confuses sparse, so we must use __force here to
175 			 * keep it from complaining.
176 			 */
177 			fh->fh_fsid[0] = new_encode_dev(MKDEV(ntohl((__force __be32)fh->fh_fsid[0]),
178 							ntohl((__force __be32)fh->fh_fsid[1])));
179 			fh->fh_fsid[1] = fh->fh_fsid[2];
180 		}
181 		data_left -= len;
182 		if (data_left < 0)
183 			return error;
184 		exp = rqst_exp_find(rqstp, fh->fh_fsid_type, fh->fh_fsid);
185 		fid = (struct fid *)(fh->fh_fsid + len);
186 	} else {
187 		__u32 tfh[2];
188 		dev_t xdev;
189 		ino_t xino;
190 
191 		if (fh->fh_size != NFS_FHSIZE)
192 			return error;
193 		/* assume old filehandle format */
194 		xdev = old_decode_dev(fh->ofh_xdev);
195 		xino = u32_to_ino_t(fh->ofh_xino);
196 		mk_fsid(FSID_DEV, tfh, xdev, xino, 0, NULL);
197 		exp = rqst_exp_find(rqstp, FSID_DEV, tfh);
198 	}
199 
200 	error = nfserr_stale;
201 	if (PTR_ERR(exp) == -ENOENT)
202 		return error;
203 
204 	if (IS_ERR(exp))
205 		return nfserrno(PTR_ERR(exp));
206 
207 	if (exp->ex_flags & NFSEXP_NOSUBTREECHECK) {
208 		/* Elevate privileges so that the lack of 'r' or 'x'
209 		 * permission on some parent directory will
210 		 * not stop exportfs_decode_fh from being able
211 		 * to reconnect a directory into the dentry cache.
212 		 * The same problem can affect "SUBTREECHECK" exports,
213 		 * but as nfsd_acceptable depends on correct
214 		 * access control settings being in effect, we cannot
215 		 * fix that case easily.
216 		 */
217 		struct cred *new = prepare_creds();
218 		if (!new) {
219 			error =  nfserrno(-ENOMEM);
220 			goto out;
221 		}
222 		new->cap_effective =
223 			cap_raise_nfsd_set(new->cap_effective,
224 					   new->cap_permitted);
225 		put_cred(override_creds(new));
226 		put_cred(new);
227 	} else {
228 		error = nfsd_setuser_and_check_port(rqstp, exp);
229 		if (error)
230 			goto out;
231 	}
232 
233 	/*
234 	 * Look up the dentry using the NFS file handle.
235 	 */
236 	error = nfserr_stale;
237 	if (rqstp->rq_vers > 2)
238 		error = nfserr_badhandle;
239 
240 	if (fh->fh_version != 1) {
241 		sfid.i32.ino = fh->ofh_ino;
242 		sfid.i32.gen = fh->ofh_generation;
243 		sfid.i32.parent_ino = fh->ofh_dirino;
244 		fid = &sfid;
245 		data_left = 3;
246 		if (fh->ofh_dirino == 0)
247 			fileid_type = FILEID_INO32_GEN;
248 		else
249 			fileid_type = FILEID_INO32_GEN_PARENT;
250 	} else
251 		fileid_type = fh->fh_fileid_type;
252 
253 	if (fileid_type == FILEID_ROOT)
254 		dentry = dget(exp->ex_path.dentry);
255 	else {
256 		dentry = exportfs_decode_fh(exp->ex_path.mnt, fid,
257 				data_left, fileid_type,
258 				nfsd_acceptable, exp);
259 	}
260 	if (dentry == NULL)
261 		goto out;
262 	if (IS_ERR(dentry)) {
263 		if (PTR_ERR(dentry) != -EINVAL)
264 			error = nfserrno(PTR_ERR(dentry));
265 		goto out;
266 	}
267 
268 	if (d_is_dir(dentry) &&
269 			(dentry->d_flags & DCACHE_DISCONNECTED)) {
270 		printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %pd2\n",
271 				dentry);
272 	}
273 
274 	fhp->fh_dentry = dentry;
275 	fhp->fh_export = exp;
276 	return 0;
277 out:
278 	exp_put(exp);
279 	return error;
280 }
281 
282 /**
283  * fh_verify - filehandle lookup and access checking
284  * @rqstp: pointer to current rpc request
285  * @fhp: filehandle to be verified
286  * @type: expected type of object pointed to by filehandle
287  * @access: type of access needed to object
288  *
289  * Look up a dentry from the on-the-wire filehandle, check the client's
290  * access to the export, and set the current task's credentials.
291  *
292  * Regardless of success or failure of fh_verify(), fh_put() should be
293  * called on @fhp when the caller is finished with the filehandle.
294  *
295  * fh_verify() may be called multiple times on a given filehandle, for
296  * example, when processing an NFSv4 compound.  The first call will look
297  * up a dentry using the on-the-wire filehandle.  Subsequent calls will
298  * skip the lookup and just perform the other checks and possibly change
299  * the current task's credentials.
300  *
301  * @type specifies the type of object expected using one of the S_IF*
302  * constants defined in include/linux/stat.h.  The caller may use zero
303  * to indicate that it doesn't care, or a negative integer to indicate
304  * that it expects something not of the given type.
305  *
306  * @access is formed from the NFSD_MAY_* constants defined in
307  * fs/nfsd/vfs.h.
308  */
309 __be32
310 fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, int access)
311 {
312 	struct svc_export *exp;
313 	struct dentry	*dentry;
314 	__be32		error;
315 
316 	dprintk("nfsd: fh_verify(%s)\n", SVCFH_fmt(fhp));
317 
318 	if (!fhp->fh_dentry) {
319 		error = nfsd_set_fh_dentry(rqstp, fhp);
320 		if (error)
321 			goto out;
322 	}
323 	dentry = fhp->fh_dentry;
324 	exp = fhp->fh_export;
325 	/*
326 	 * We still have to do all these permission checks, even when
327 	 * fh_dentry is already set:
328 	 * 	- fh_verify may be called multiple times with different
329 	 * 	  "access" arguments (e.g. nfsd_proc_create calls
330 	 * 	  fh_verify(...,NFSD_MAY_EXEC) first, then later (in
331 	 * 	  nfsd_create) calls fh_verify(...,NFSD_MAY_CREATE).
332 	 *	- in the NFSv4 case, the filehandle may have been filled
333 	 *	  in by fh_compose, and given a dentry, but further
334 	 *	  compound operations performed with that filehandle
335 	 *	  still need permissions checks.  In the worst case, a
336 	 *	  mountpoint crossing may have changed the export
337 	 *	  options, and we may now need to use a different uid
338 	 *	  (for example, if different id-squashing options are in
339 	 *	  effect on the new filesystem).
340 	 */
341 	error = check_pseudo_root(rqstp, dentry, exp);
342 	if (error)
343 		goto out;
344 
345 	error = nfsd_setuser_and_check_port(rqstp, exp);
346 	if (error)
347 		goto out;
348 
349 	error = nfsd_mode_check(rqstp, dentry, type);
350 	if (error)
351 		goto out;
352 
353 	/*
354 	 * pseudoflavor restrictions are not enforced on NLM,
355 	 * which clients virtually always use auth_sys for,
356 	 * even while using RPCSEC_GSS for NFS.
357 	 */
358 	if (access & NFSD_MAY_LOCK || access & NFSD_MAY_BYPASS_GSS)
359 		goto skip_pseudoflavor_check;
360 	/*
361 	 * Clients may expect to be able to use auth_sys during mount,
362 	 * even if they use gss for everything else; see section 2.3.2
363 	 * of rfc 2623.
364 	 */
365 	if (access & NFSD_MAY_BYPASS_GSS_ON_ROOT
366 			&& exp->ex_path.dentry == dentry)
367 		goto skip_pseudoflavor_check;
368 
369 	error = check_nfsd_access(exp, rqstp);
370 	if (error)
371 		goto out;
372 
373 skip_pseudoflavor_check:
374 	/* Finally, check access permissions. */
375 	error = nfsd_permission(rqstp, exp, dentry, access);
376 
377 	if (error) {
378 		dprintk("fh_verify: %pd2 permission failure, "
379 			"acc=%x, error=%d\n",
380 			dentry,
381 			access, ntohl(error));
382 	}
383 out:
384 	if (error == nfserr_stale)
385 		nfsdstats.fh_stale++;
386 	return error;
387 }
388 
389 
390 /*
391  * Compose a file handle for an NFS reply.
392  *
393  * Note that when first composed, the dentry may not yet have
394  * an inode.  In this case a call to fh_update should be made
395  * before the fh goes out on the wire ...
396  */
397 static void _fh_update(struct svc_fh *fhp, struct svc_export *exp,
398 		struct dentry *dentry)
399 {
400 	if (dentry != exp->ex_path.dentry) {
401 		struct fid *fid = (struct fid *)
402 			(fhp->fh_handle.fh_fsid + fhp->fh_handle.fh_size/4 - 1);
403 		int maxsize = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
404 		int subtreecheck = !(exp->ex_flags & NFSEXP_NOSUBTREECHECK);
405 
406 		fhp->fh_handle.fh_fileid_type =
407 			exportfs_encode_fh(dentry, fid, &maxsize, subtreecheck);
408 		fhp->fh_handle.fh_size += maxsize * 4;
409 	} else {
410 		fhp->fh_handle.fh_fileid_type = FILEID_ROOT;
411 	}
412 }
413 
414 /*
415  * for composing old style file handles
416  */
417 static inline void _fh_update_old(struct dentry *dentry,
418 				  struct svc_export *exp,
419 				  struct knfsd_fh *fh)
420 {
421 	fh->ofh_ino = ino_t_to_u32(d_inode(dentry)->i_ino);
422 	fh->ofh_generation = d_inode(dentry)->i_generation;
423 	if (d_is_dir(dentry) ||
424 	    (exp->ex_flags & NFSEXP_NOSUBTREECHECK))
425 		fh->ofh_dirino = 0;
426 }
427 
428 static bool is_root_export(struct svc_export *exp)
429 {
430 	return exp->ex_path.dentry == exp->ex_path.dentry->d_sb->s_root;
431 }
432 
433 static struct super_block *exp_sb(struct svc_export *exp)
434 {
435 	return exp->ex_path.dentry->d_sb;
436 }
437 
438 static bool fsid_type_ok_for_exp(u8 fsid_type, struct svc_export *exp)
439 {
440 	switch (fsid_type) {
441 	case FSID_DEV:
442 		if (!old_valid_dev(exp_sb(exp)->s_dev))
443 			return 0;
444 		/* FALL THROUGH */
445 	case FSID_MAJOR_MINOR:
446 	case FSID_ENCODE_DEV:
447 		return exp_sb(exp)->s_type->fs_flags & FS_REQUIRES_DEV;
448 	case FSID_NUM:
449 		return exp->ex_flags & NFSEXP_FSID;
450 	case FSID_UUID8:
451 	case FSID_UUID16:
452 		if (!is_root_export(exp))
453 			return 0;
454 		/* fall through */
455 	case FSID_UUID4_INUM:
456 	case FSID_UUID16_INUM:
457 		return exp->ex_uuid != NULL;
458 	}
459 	return 1;
460 }
461 
462 
463 static void set_version_and_fsid_type(struct svc_fh *fhp, struct svc_export *exp, struct svc_fh *ref_fh)
464 {
465 	u8 version;
466 	u8 fsid_type;
467 retry:
468 	version = 1;
469 	if (ref_fh && ref_fh->fh_export == exp) {
470 		version = ref_fh->fh_handle.fh_version;
471 		fsid_type = ref_fh->fh_handle.fh_fsid_type;
472 
473 		ref_fh = NULL;
474 
475 		switch (version) {
476 		case 0xca:
477 			fsid_type = FSID_DEV;
478 			break;
479 		case 1:
480 			break;
481 		default:
482 			goto retry;
483 		}
484 
485 		/*
486 		 * As the fsid -> filesystem mapping was guided by
487 		 * user-space, there is no guarantee that the filesystem
488 		 * actually supports that fsid type. If it doesn't we
489 		 * loop around again without ref_fh set.
490 		 */
491 		if (!fsid_type_ok_for_exp(fsid_type, exp))
492 			goto retry;
493 	} else if (exp->ex_flags & NFSEXP_FSID) {
494 		fsid_type = FSID_NUM;
495 	} else if (exp->ex_uuid) {
496 		if (fhp->fh_maxsize >= 64) {
497 			if (is_root_export(exp))
498 				fsid_type = FSID_UUID16;
499 			else
500 				fsid_type = FSID_UUID16_INUM;
501 		} else {
502 			if (is_root_export(exp))
503 				fsid_type = FSID_UUID8;
504 			else
505 				fsid_type = FSID_UUID4_INUM;
506 		}
507 	} else if (!old_valid_dev(exp_sb(exp)->s_dev))
508 		/* for newer device numbers, we must use a newer fsid format */
509 		fsid_type = FSID_ENCODE_DEV;
510 	else
511 		fsid_type = FSID_DEV;
512 	fhp->fh_handle.fh_version = version;
513 	if (version)
514 		fhp->fh_handle.fh_fsid_type = fsid_type;
515 }
516 
517 __be32
518 fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry,
519 	   struct svc_fh *ref_fh)
520 {
521 	/* ref_fh is a reference file handle.
522 	 * if it is non-null and for the same filesystem, then we should compose
523 	 * a filehandle which is of the same version, where possible.
524 	 * Currently, that means that if ref_fh->fh_handle.fh_version == 0xca
525 	 * Then create a 32byte filehandle using nfs_fhbase_old
526 	 *
527 	 */
528 
529 	struct inode * inode = d_inode(dentry);
530 	dev_t ex_dev = exp_sb(exp)->s_dev;
531 
532 	dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %pd2, ino=%ld)\n",
533 		MAJOR(ex_dev), MINOR(ex_dev),
534 		(long) d_inode(exp->ex_path.dentry)->i_ino,
535 		dentry,
536 		(inode ? inode->i_ino : 0));
537 
538 	/* Choose filehandle version and fsid type based on
539 	 * the reference filehandle (if it is in the same export)
540 	 * or the export options.
541 	 */
542 	set_version_and_fsid_type(fhp, exp, ref_fh);
543 
544 	if (ref_fh == fhp)
545 		fh_put(ref_fh);
546 
547 	if (fhp->fh_locked || fhp->fh_dentry) {
548 		printk(KERN_ERR "fh_compose: fh %pd2 not initialized!\n",
549 		       dentry);
550 	}
551 	if (fhp->fh_maxsize < NFS_FHSIZE)
552 		printk(KERN_ERR "fh_compose: called with maxsize %d! %pd2\n",
553 		       fhp->fh_maxsize,
554 		       dentry);
555 
556 	fhp->fh_dentry = dget(dentry); /* our internal copy */
557 	fhp->fh_export = exp_get(exp);
558 
559 	if (fhp->fh_handle.fh_version == 0xca) {
560 		/* old style filehandle please */
561 		memset(&fhp->fh_handle.fh_base, 0, NFS_FHSIZE);
562 		fhp->fh_handle.fh_size = NFS_FHSIZE;
563 		fhp->fh_handle.ofh_dcookie = 0xfeebbaca;
564 		fhp->fh_handle.ofh_dev =  old_encode_dev(ex_dev);
565 		fhp->fh_handle.ofh_xdev = fhp->fh_handle.ofh_dev;
566 		fhp->fh_handle.ofh_xino =
567 			ino_t_to_u32(d_inode(exp->ex_path.dentry)->i_ino);
568 		fhp->fh_handle.ofh_dirino = ino_t_to_u32(parent_ino(dentry));
569 		if (inode)
570 			_fh_update_old(dentry, exp, &fhp->fh_handle);
571 	} else {
572 		fhp->fh_handle.fh_size =
573 			key_len(fhp->fh_handle.fh_fsid_type) + 4;
574 		fhp->fh_handle.fh_auth_type = 0;
575 
576 		mk_fsid(fhp->fh_handle.fh_fsid_type,
577 			fhp->fh_handle.fh_fsid,
578 			ex_dev,
579 			d_inode(exp->ex_path.dentry)->i_ino,
580 			exp->ex_fsid, exp->ex_uuid);
581 
582 		if (inode)
583 			_fh_update(fhp, exp, dentry);
584 		if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID) {
585 			fh_put(fhp);
586 			return nfserr_opnotsupp;
587 		}
588 	}
589 
590 	return 0;
591 }
592 
593 /*
594  * Update file handle information after changing a dentry.
595  * This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create
596  */
597 __be32
598 fh_update(struct svc_fh *fhp)
599 {
600 	struct dentry *dentry;
601 
602 	if (!fhp->fh_dentry)
603 		goto out_bad;
604 
605 	dentry = fhp->fh_dentry;
606 	if (d_really_is_negative(dentry))
607 		goto out_negative;
608 	if (fhp->fh_handle.fh_version != 1) {
609 		_fh_update_old(dentry, fhp->fh_export, &fhp->fh_handle);
610 	} else {
611 		if (fhp->fh_handle.fh_fileid_type != FILEID_ROOT)
612 			return 0;
613 
614 		_fh_update(fhp, fhp->fh_export, dentry);
615 		if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID)
616 			return nfserr_opnotsupp;
617 	}
618 	return 0;
619 out_bad:
620 	printk(KERN_ERR "fh_update: fh not verified!\n");
621 	return nfserr_serverfault;
622 out_negative:
623 	printk(KERN_ERR "fh_update: %pd2 still negative!\n",
624 		dentry);
625 	return nfserr_serverfault;
626 }
627 
628 /*
629  * Release a file handle.
630  */
631 void
632 fh_put(struct svc_fh *fhp)
633 {
634 	struct dentry * dentry = fhp->fh_dentry;
635 	struct svc_export * exp = fhp->fh_export;
636 	if (dentry) {
637 		fh_unlock(fhp);
638 		fhp->fh_dentry = NULL;
639 		dput(dentry);
640 		fh_clear_wcc(fhp);
641 	}
642 	fh_drop_write(fhp);
643 	if (exp) {
644 		exp_put(exp);
645 		fhp->fh_export = NULL;
646 	}
647 	return;
648 }
649 
650 /*
651  * Shorthand for dprintk()'s
652  */
653 char * SVCFH_fmt(struct svc_fh *fhp)
654 {
655 	struct knfsd_fh *fh = &fhp->fh_handle;
656 
657 	static char buf[80];
658 	sprintf(buf, "%d: %08x %08x %08x %08x %08x %08x",
659 		fh->fh_size,
660 		fh->fh_base.fh_pad[0],
661 		fh->fh_base.fh_pad[1],
662 		fh->fh_base.fh_pad[2],
663 		fh->fh_base.fh_pad[3],
664 		fh->fh_base.fh_pad[4],
665 		fh->fh_base.fh_pad[5]);
666 	return buf;
667 }
668 
669 enum fsid_source fsid_source(struct svc_fh *fhp)
670 {
671 	if (fhp->fh_handle.fh_version != 1)
672 		return FSIDSOURCE_DEV;
673 	switch(fhp->fh_handle.fh_fsid_type) {
674 	case FSID_DEV:
675 	case FSID_ENCODE_DEV:
676 	case FSID_MAJOR_MINOR:
677 		if (exp_sb(fhp->fh_export)->s_type->fs_flags & FS_REQUIRES_DEV)
678 			return FSIDSOURCE_DEV;
679 		break;
680 	case FSID_NUM:
681 		if (fhp->fh_export->ex_flags & NFSEXP_FSID)
682 			return FSIDSOURCE_FSID;
683 		break;
684 	default:
685 		break;
686 	}
687 	/* either a UUID type filehandle, or the filehandle doesn't
688 	 * match the export.
689 	 */
690 	if (fhp->fh_export->ex_flags & NFSEXP_FSID)
691 		return FSIDSOURCE_FSID;
692 	if (fhp->fh_export->ex_uuid)
693 		return FSIDSOURCE_UUID;
694 	return FSIDSOURCE_DEV;
695 }
696