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   1 /*
   2  * linux/fs/nfsd/nfsfh.c
   3  *
   4  * NFS server file handle treatment.
   5  *
   6  * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
   7  * Portions Copyright (C) 1999 G. Allen Morris III <gam3@acm.org>
   8  * Extensive rewrite by Neil Brown <neilb@cse.unsw.edu.au> Southern-Spring 1999
   9  * ... and again Southern-Winter 2001 to support export_operations
  10  */
  11
  12 #include <linux/slab.h>
  13 #include <linux/fs.h>
  14 #include <linux/unistd.h>
  15 #include <linux/string.h>
  16 #include <linux/stat.h>
  17 #include <linux/dcache.h>
  18 #include <linux/exportfs.h>
  19 #include <linux/mount.h>
  20
  21 #include <linux/sunrpc/clnt.h>
  22 #include <linux/sunrpc/svc.h>
  23 #include <linux/sunrpc/svcauth_gss.h>
  24 #include <linux/nfsd/nfsd.h>
  25 #include "auth.h"
  26
  27 #define NFSDDBG_FACILITY                NFSDDBG_FH
  28
  29
  30 static int nfsd_nr_verified;
  31 static int nfsd_nr_put;
  32
  33 /*
  34  * our acceptability function.
  35  * if NOSUBTREECHECK, accept anything
  36  * if not, require that we can walk up to exp->ex_dentry
  37  * doing some checks on the 'x' bits
  38  */
  39 static int nfsd_acceptable(void *expv, struct dentry *dentry)
  40 {
  41         struct svc_export *exp = expv;
  42         int rv;
  43         struct dentry *tdentry;
  44         struct dentry *parent;
  45
  46         if (exp->ex_flags & NFSEXP_NOSUBTREECHECK)
  47                 return 1;
  48
  49         tdentry = dget(dentry);
  50         while (tdentry != exp->ex_path.dentry && !IS_ROOT(tdentry)) {
  51                 /* make sure parents give x permission to user */
  52                 int err;
  53                 parent = dget_parent(tdentry);
  54                 err = inode_permission(parent->d_inode, MAY_EXEC);
  55                 if (err < 0) {
  56                         dput(parent);
  57                         break;
  58                 }
  59                 dput(tdentry);
  60                 tdentry = parent;
  61         }
  62         if (tdentry != exp->ex_path.dentry)
  63                 dprintk("nfsd_acceptable failed at %p %s\n", tdentry, tdentry->d_name.name);
  64         rv = (tdentry == exp->ex_path.dentry);
  65         dput(tdentry);
  66         return rv;
  67 }
  68
  69 /* Type check. The correct error return for type mismatches does not seem to be
  70  * generally agreed upon. SunOS seems to use EISDIR if file isn't S_IFREG; a
  71  * comment in the NFSv3 spec says this is incorrect (implementation notes for
  72  * the write call).
  73  */
  74 static inline __be32
  75 nfsd_mode_check(struct svc_rqst *rqstp, umode_t mode, int type)
  76 {
  77         /* Type can be negative when creating hardlinks - not to a dir */
  78         if (type > 0 && (mode & S_IFMT) != type) {
  79                 if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK)
  80                         return nfserr_symlink;
  81                 else if (type == S_IFDIR)
  82                         return nfserr_notdir;
  83                 else if ((mode & S_IFMT) == S_IFDIR)
  84                         return nfserr_isdir;
  85                 else
  86                         return nfserr_inval;
  87         }
  88         if (type < 0 && (mode & S_IFMT) == -type) {
  89                 if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK)
  90                         return nfserr_symlink;
  91                 else if (type == -S_IFDIR)
  92                         return nfserr_isdir;
  93                 else
  94                         return nfserr_notdir;
  95         }
  96         return 0;
  97 }
  98
  99 static __be32 nfsd_setuser_and_check_port(struct svc_rqst *rqstp,
 100                                           struct svc_export *exp)
 101 {
 102         /* Check if the request originated from a secure port. */
 103         if (!rqstp->rq_secure && EX_SECURE(exp)) {
 104                 RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
 105                 dprintk(KERN_WARNING
 106                        "nfsd: request from insecure port %s!\n",
 107                        svc_print_addr(rqstp, buf, sizeof(buf)));
 108                 return nfserr_perm;
 109         }
 110
 111         /* Set user creds for this exportpoint */
 112         return nfserrno(nfsd_setuser(rqstp, exp));
 113 }
 114
 115 /*
 116  * Use the given filehandle to look up the corresponding export and
 117  * dentry.  On success, the results are used to set fh_export and
 118  * fh_dentry.
 119  */
 120 static __be32 nfsd_set_fh_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp)
 121 {
 122         struct knfsd_fh *fh = &fhp->fh_handle;
 123         struct fid *fid = NULL, sfid;
 124         struct svc_export *exp;
 125         struct dentry *dentry;
 126         int fileid_type;
 127         int data_left = fh->fh_size/4;
 128         __be32 error;
 129
 130         error = nfserr_stale;
 131         if (rqstp->rq_vers > 2)
 132                 error = nfserr_badhandle;
 133         if (rqstp->rq_vers == 4 && fh->fh_size == 0)
 134                 return nfserr_nofilehandle;
 135
 136         if (fh->fh_version == 1) {
 137                 int len;
 138
 139                 if (--data_left < 0)
 140                         return error;
 141                 if (fh->fh_auth_type != 0)
 142                         return error;
 143                 len = key_len(fh->fh_fsid_type) / 4;
 144                 if (len == 0)
 145                         return error;
 146                 if  (fh->fh_fsid_type == FSID_MAJOR_MINOR) {
 147                         /* deprecated, convert to type 3 */
 148                         len = key_len(FSID_ENCODE_DEV)/4;
 149                         fh->fh_fsid_type = FSID_ENCODE_DEV;
 150                         fh->fh_fsid[0] = new_encode_dev(MKDEV(ntohl(fh->fh_fsid[0]), ntohl(fh->fh_fsid[1])));
 151                         fh->fh_fsid[1] = fh->fh_fsid[2];
 152                 }
 153                 data_left -= len;
 154                 if (data_left < 0)
 155                         return error;
 156                 exp = rqst_exp_find(rqstp, fh->fh_fsid_type, fh->fh_auth);
 157                 fid = (struct fid *)(fh->fh_auth + len);
 158         } else {
 159                 __u32 tfh[2];
 160                 dev_t xdev;
 161                 ino_t xino;
 162
 163                 if (fh->fh_size != NFS_FHSIZE)
 164                         return error;
 165                 /* assume old filehandle format */
 166                 xdev = old_decode_dev(fh->ofh_xdev);
 167                 xino = u32_to_ino_t(fh->ofh_xino);
 168                 mk_fsid(FSID_DEV, tfh, xdev, xino, 0, NULL);
 169                 exp = rqst_exp_find(rqstp, FSID_DEV, tfh);
 170         }
 171
 172         error = nfserr_stale;
 173         if (PTR_ERR(exp) == -ENOENT)
 174                 return error;
 175
 176         if (IS_ERR(exp))
 177                 return nfserrno(PTR_ERR(exp));
 178
 179         if (exp->ex_flags & NFSEXP_NOSUBTREECHECK) {
 180                 /* Elevate privileges so that the lack of 'r' or 'x'
 181                  * permission on some parent directory will
 182                  * not stop exportfs_decode_fh from being able
 183                  * to reconnect a directory into the dentry cache.
 184                  * The same problem can affect "SUBTREECHECK" exports,
 185                  * but as nfsd_acceptable depends on correct
 186                  * access control settings being in effect, we cannot
 187                  * fix that case easily.
 188                  */
 189                 struct cred *new = prepare_creds();
 190                 if (!new)
 191                         return nfserrno(-ENOMEM);
 192                 new->cap_effective =
 193                         cap_raise_nfsd_set(new->cap_effective,
 194                                            new->cap_permitted);
 195                 put_cred(override_creds(new));
 196                 put_cred(new);
 197         } else {
 198                 error = nfsd_setuser_and_check_port(rqstp, exp);
 199                 if (error)
 200                         goto out;
 201         }
 202
 203         /*
 204          * Look up the dentry using the NFS file handle.
 205          */
 206         error = nfserr_stale;
 207         if (rqstp->rq_vers > 2)
 208                 error = nfserr_badhandle;
 209
 210         if (fh->fh_version != 1) {
 211                 sfid.i32.ino = fh->ofh_ino;
 212                 sfid.i32.gen = fh->ofh_generation;
 213                 sfid.i32.parent_ino = fh->ofh_dirino;
 214                 fid = &sfid;
 215                 data_left = 3;
 216                 if (fh->ofh_dirino == 0)
 217                         fileid_type = FILEID_INO32_GEN;
 218                 else
 219                         fileid_type = FILEID_INO32_GEN_PARENT;
 220         } else
 221                 fileid_type = fh->fh_fileid_type;
 222
 223         if (fileid_type == FILEID_ROOT)
 224                 dentry = dget(exp->ex_path.dentry);
 225         else {
 226                 dentry = exportfs_decode_fh(exp->ex_path.mnt, fid,
 227                                 data_left, fileid_type,
 228                                 nfsd_acceptable, exp);
 229         }
 230         if (dentry == NULL)
 231                 goto out;
 232         if (IS_ERR(dentry)) {
 233                 if (PTR_ERR(dentry) != -EINVAL)
 234                         error = nfserrno(PTR_ERR(dentry));
 235                 goto out;
 236         }
 237
 238         if (exp->ex_flags & NFSEXP_NOSUBTREECHECK) {
 239                 error = nfsd_setuser_and_check_port(rqstp, exp);
 240                 if (error) {
 241                         dput(dentry);
 242                         goto out;
 243                 }
 244         }
 245
 246         if (S_ISDIR(dentry->d_inode->i_mode) &&
 247                         (dentry->d_flags & DCACHE_DISCONNECTED)) {
 248                 printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %s/%s\n",
 249                                 dentry->d_parent->d_name.name, dentry->d_name.name);
 250         }
 251
 252         fhp->fh_dentry = dentry;
 253         fhp->fh_export = exp;
 254         nfsd_nr_verified++;
 255         return 0;
 256 out:
 257         exp_put(exp);
 258         return error;
 259 }
 260
 261 /*
 262  * Perform sanity checks on the dentry in a client's file handle.
 263  *
 264  * Note that the file handle dentry may need to be freed even after
 265  * an error return.
 266  *
 267  * This is only called at the start of an nfsproc call, so fhp points to
 268  * a svc_fh which is all 0 except for the over-the-wire file handle.
 269  */
 270 __be32
 271 fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access)
 272 {
 273         struct svc_export *exp;
 274         struct dentry   *dentry;
 275         __be32          error;
 276
 277         dprintk("nfsd: fh_verify(%s)\n", SVCFH_fmt(fhp));
 278
 279         if (!fhp->fh_dentry) {
 280                 error = nfsd_set_fh_dentry(rqstp, fhp);
 281                 if (error)
 282                         goto out;
 283                 dentry = fhp->fh_dentry;
 284                 exp = fhp->fh_export;
 285         } else {
 286                 /*
 287                  * just rechecking permissions
 288                  * (e.g. nfsproc_create calls fh_verify, then nfsd_create
 289                  * does as well)
 290                  */
 291                 dprintk("nfsd: fh_verify - just checking\n");
 292                 dentry = fhp->fh_dentry;
 293                 exp = fhp->fh_export;
 294                 /*
 295                  * Set user creds for this exportpoint; necessary even
 296                  * in the "just checking" case because this may be a
 297                  * filehandle that was created by fh_compose, and that
 298                  * is about to be used in another nfsv4 compound
 299                  * operation.
 300                  */
 301                 error = nfsd_setuser_and_check_port(rqstp, exp);
 302                 if (error)
 303                         goto out;
 304         }
 305
 306         error = nfsd_mode_check(rqstp, dentry->d_inode->i_mode, type);
 307         if (error)
 308                 goto out;
 309
 310         /*
 311          * pseudoflavor restrictions are not enforced on NLM,
 312          * which clients virtually always use auth_sys for,
 313          * even while using RPCSEC_GSS for NFS.
 314          */
 315         if (access & NFSD_MAY_LOCK)
 316                 goto skip_pseudoflavor_check;
 317         /*
 318          * Clients may expect to be able to use auth_sys during mount,
 319          * even if they use gss for everything else; see section 2.3.2
 320          * of rfc 2623.
 321          */
 322         if (access & NFSD_MAY_BYPASS_GSS_ON_ROOT
 323                         && exp->ex_path.dentry == dentry)
 324                 goto skip_pseudoflavor_check;
 325
 326         error = check_nfsd_access(exp, rqstp);
 327         if (error)
 328                 goto out;
 329
 330 skip_pseudoflavor_check:
 331         /* Finally, check access permissions. */
 332         error = nfsd_permission(rqstp, exp, dentry, access);
 333
 334         if (error) {
 335                 dprintk("fh_verify: %s/%s permission failure, "
 336                         "acc=%x, error=%d\n",
 337                         dentry->d_parent->d_name.name,
 338                         dentry->d_name.name,
 339                         access, ntohl(error));
 340         }
 341 out:
 342         if (error == nfserr_stale)
 343                 nfsdstats.fh_stale++;
 344         return error;
 345 }
 346
 347
 348 /*
 349  * Compose a file handle for an NFS reply.
 350  *
 351  * Note that when first composed, the dentry may not yet have
 352  * an inode.  In this case a call to fh_update should be made
 353  * before the fh goes out on the wire ...
 354  */
 355 static void _fh_update(struct svc_fh *fhp, struct svc_export *exp,
 356                 struct dentry *dentry)
 357 {
 358         if (dentry != exp->ex_path.dentry) {
 359                 struct fid *fid = (struct fid *)
 360                         (fhp->fh_handle.fh_auth + fhp->fh_handle.fh_size/4 - 1);
 361                 int maxsize = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
 362                 int subtreecheck = !(exp->ex_flags & NFSEXP_NOSUBTREECHECK);
 363
 364                 fhp->fh_handle.fh_fileid_type =
 365                         exportfs_encode_fh(dentry, fid, &maxsize, subtreecheck);
 366                 fhp->fh_handle.fh_size += maxsize * 4;
 367         } else {
 368                 fhp->fh_handle.fh_fileid_type = FILEID_ROOT;
 369         }
 370 }
 371
 372 /*
 373  * for composing old style file handles
 374  */
 375 static inline void _fh_update_old(struct dentry *dentry,
 376                                   struct svc_export *exp,
 377                                   struct knfsd_fh *fh)
 378 {
 379         fh->ofh_ino = ino_t_to_u32(dentry->d_inode->i_ino);
 380         fh->ofh_generation = dentry->d_inode->i_generation;
 381         if (S_ISDIR(dentry->d_inode->i_mode) ||
 382             (exp->ex_flags & NFSEXP_NOSUBTREECHECK))
 383                 fh->ofh_dirino = 0;
 384 }
 385
 386 __be32
 387 fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry,
 388            struct svc_fh *ref_fh)
 389 {
 390         /* ref_fh is a reference file handle.
 391          * if it is non-null and for the same filesystem, then we should compose
 392          * a filehandle which is of the same version, where possible.
 393          * Currently, that means that if ref_fh->fh_handle.fh_version == 0xca
 394          * Then create a 32byte filehandle using nfs_fhbase_old
 395          *
 396          */
 397
 398         u8 version;
 399         u8 fsid_type = 0;
 400         struct inode * inode = dentry->d_inode;
 401         struct dentry *parent = dentry->d_parent;
 402         __u32 *datap;
 403         dev_t ex_dev = exp->ex_path.dentry->d_inode->i_sb->s_dev;
 404         int root_export = (exp->ex_path.dentry == exp->ex_path.dentry->d_sb->s_root);
 405
 406         dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %s/%s, ino=%ld)\n",
 407                 MAJOR(ex_dev), MINOR(ex_dev),
 408                 (long) exp->ex_path.dentry->d_inode->i_ino,
 409                 parent->d_name.name, dentry->d_name.name,
 410                 (inode ? inode->i_ino : 0));
 411
 412         /* Choose filehandle version and fsid type based on
 413          * the reference filehandle (if it is in the same export)
 414          * or the export options.
 415          */
 416  retry:
 417         version = 1;
 418         if (ref_fh && ref_fh->fh_export == exp) {
 419                 version = ref_fh->fh_handle.fh_version;
 420                 fsid_type = ref_fh->fh_handle.fh_fsid_type;
 421
 422                 if (ref_fh == fhp)
 423                         fh_put(ref_fh);
 424                 ref_fh = NULL;
 425
 426                 switch (version) {
 427                 case 0xca:
 428                         fsid_type = FSID_DEV;
 429                         break;
 430                 case 1:
 431                         break;
 432                 default:
 433                         goto retry;
 434                 }
 435
 436                 /* Need to check that this type works for this
 437                  * export point.  As the fsid -> filesystem mapping
 438                  * was guided by user-space, there is no guarantee
 439                  * that the filesystem actually supports that fsid
 440                  * type. If it doesn't we loop around again without
 441                  * ref_fh set.
 442                  */
 443                 switch(fsid_type) {
 444                 case FSID_DEV:
 445                         if (!old_valid_dev(ex_dev))
 446                                 goto retry;
 447                         /* FALL THROUGH */
 448                 case FSID_MAJOR_MINOR:
 449                 case FSID_ENCODE_DEV:
 450                         if (!(exp->ex_path.dentry->d_inode->i_sb->s_type->fs_flags
 451                               & FS_REQUIRES_DEV))
 452                                 goto retry;
 453                         break;
 454                 case FSID_NUM:
 455                         if (! (exp->ex_flags & NFSEXP_FSID))
 456                                 goto retry;
 457                         break;
 458                 case FSID_UUID8:
 459                 case FSID_UUID16:
 460                         if (!root_export)
 461                                 goto retry;
 462                         /* fall through */
 463                 case FSID_UUID4_INUM:
 464                 case FSID_UUID16_INUM:
 465                         if (exp->ex_uuid == NULL)
 466                                 goto retry;
 467                         break;
 468                 }
 469         } else if (exp->ex_uuid) {
 470                 if (fhp->fh_maxsize >= 64) {
 471                         if (root_export)
 472                                 fsid_type = FSID_UUID16;
 473                         else
 474                                 fsid_type = FSID_UUID16_INUM;
 475                 } else {
 476                         if (root_export)
 477                                 fsid_type = FSID_UUID8;
 478                         else
 479                                 fsid_type = FSID_UUID4_INUM;
 480                 }
 481         } else if (exp->ex_flags & NFSEXP_FSID)
 482                 fsid_type = FSID_NUM;
 483         else if (!old_valid_dev(ex_dev))
 484                 /* for newer device numbers, we must use a newer fsid format */
 485                 fsid_type = FSID_ENCODE_DEV;
 486         else
 487                 fsid_type = FSID_DEV;
 488
 489         if (ref_fh == fhp)
 490                 fh_put(ref_fh);
 491
 492         if (fhp->fh_locked || fhp->fh_dentry) {
 493                 printk(KERN_ERR "fh_compose: fh %s/%s not initialized!\n",
 494                        parent->d_name.name, dentry->d_name.name);
 495         }
 496         if (fhp->fh_maxsize < NFS_FHSIZE)
 497                 printk(KERN_ERR "fh_compose: called with maxsize %d! %s/%s\n",
 498                        fhp->fh_maxsize,
 499                        parent->d_name.name, dentry->d_name.name);
 500
 501         fhp->fh_dentry = dget(dentry); /* our internal copy */
 502         fhp->fh_export = exp;
 503         cache_get(&exp->h);
 504
 505         if (version == 0xca) {
 506                 /* old style filehandle please */
 507                 memset(&fhp->fh_handle.fh_base, 0, NFS_FHSIZE);
 508                 fhp->fh_handle.fh_size = NFS_FHSIZE;
 509                 fhp->fh_handle.ofh_dcookie = 0xfeebbaca;
 510                 fhp->fh_handle.ofh_dev =  old_encode_dev(ex_dev);
 511                 fhp->fh_handle.ofh_xdev = fhp->fh_handle.ofh_dev;
 512                 fhp->fh_handle.ofh_xino =
 513                         ino_t_to_u32(exp->ex_path.dentry->d_inode->i_ino);
 514                 fhp->fh_handle.ofh_dirino = ino_t_to_u32(parent_ino(dentry));
 515                 if (inode)
 516                         _fh_update_old(dentry, exp, &fhp->fh_handle);
 517         } else {
 518                 int len;
 519                 fhp->fh_handle.fh_version = 1;
 520                 fhp->fh_handle.fh_auth_type = 0;
 521                 datap = fhp->fh_handle.fh_auth+0;
 522                 fhp->fh_handle.fh_fsid_type = fsid_type;
 523                 mk_fsid(fsid_type, datap, ex_dev,
 524                         exp->ex_path.dentry->d_inode->i_ino,
 525                         exp->ex_fsid, exp->ex_uuid);
 526
 527                 len = key_len(fsid_type);
 528                 datap += len/4;
 529                 fhp->fh_handle.fh_size = 4 + len;
 530
 531                 if (inode)
 532                         _fh_update(fhp, exp, dentry);
 533                 if (fhp->fh_handle.fh_fileid_type == 255)
 534                         return nfserr_opnotsupp;
 535         }
 536
 537         nfsd_nr_verified++;
 538         return 0;
 539 }
 540
 541 /*
 542  * Update file handle information after changing a dentry.
 543  * This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create
 544  */
 545 __be32
 546 fh_update(struct svc_fh *fhp)
 547 {
 548         struct dentry *dentry;
 549
 550         if (!fhp->fh_dentry)
 551                 goto out_bad;
 552
 553         dentry = fhp->fh_dentry;
 554         if (!dentry->d_inode)
 555                 goto out_negative;
 556         if (fhp->fh_handle.fh_version != 1) {
 557                 _fh_update_old(dentry, fhp->fh_export, &fhp->fh_handle);
 558         } else {
 559                 if (fhp->fh_handle.fh_fileid_type != FILEID_ROOT)
 560                         goto out;
 561
 562                 _fh_update(fhp, fhp->fh_export, dentry);
 563                 if (fhp->fh_handle.fh_fileid_type == 255)
 564                         return nfserr_opnotsupp;
 565         }
 566 out:
 567         return 0;
 568
 569 out_bad:
 570         printk(KERN_ERR "fh_update: fh not verified!\n");
 571         goto out;
 572 out_negative:
 573         printk(KERN_ERR "fh_update: %s/%s still negative!\n",
 574                 dentry->d_parent->d_name.name, dentry->d_name.name);
 575         goto out;
 576 }
 577
 578 /*
 579  * Release a file handle.
 580  */
 581 void
 582 fh_put(struct svc_fh *fhp)
 583 {
 584         struct dentry * dentry = fhp->fh_dentry;
 585         struct svc_export * exp = fhp->fh_export;
 586         if (dentry) {
 587                 fh_unlock(fhp);
 588                 fhp->fh_dentry = NULL;
 589                 dput(dentry);
 590 #ifdef CONFIG_NFSD_V3
 591                 fhp->fh_pre_saved = 0;
 592                 fhp->fh_post_saved = 0;
 593 #endif
 594                 nfsd_nr_put++;
 595         }
 596         if (exp) {
 597                 cache_put(&exp->h, &svc_export_cache);
 598                 fhp->fh_export = NULL;
 599         }
 600         return;
 601 }
 602
 603 /*
 604  * Shorthand for dprintk()'s
 605  */
 606 char * SVCFH_fmt(struct svc_fh *fhp)
 607 {
 608         struct knfsd_fh *fh = &fhp->fh_handle;
 609
 610         static char buf[80];
 611         sprintf(buf, "%d: %08x %08x %08x %08x %08x %08x",
 612                 fh->fh_size,
 613                 fh->fh_base.fh_pad[0],
 614                 fh->fh_base.fh_pad[1],
 615                 fh->fh_base.fh_pad[2],
 616                 fh->fh_base.fh_pad[3],
 617                 fh->fh_base.fh_pad[4],
 618                 fh->fh_base.fh_pad[5]);
 619         return buf;
 620 }
 621
 622 enum fsid_source fsid_source(struct svc_fh *fhp)
 623 {
 624         if (fhp->fh_handle.fh_version != 1)
 625                 return FSIDSOURCE_DEV;
 626         switch(fhp->fh_handle.fh_fsid_type) {
 627         case FSID_DEV:
 628         case FSID_ENCODE_DEV:
 629         case FSID_MAJOR_MINOR:
 630                 if (fhp->fh_export->ex_path.dentry->d_inode->i_sb->s_type->fs_flags
 631                     & FS_REQUIRES_DEV)
 632                         return FSIDSOURCE_DEV;
 633                 break;
 634         case FSID_NUM:
 635                 if (fhp->fh_export->ex_flags & NFSEXP_FSID)
 636                         return FSIDSOURCE_FSID;
 637                 break;
 638         default:
 639                 break;
 640         }
 641         /* either a UUID type filehandle, or the filehandle doesn't
 642          * match the export.
 643          */
 644         if (fhp->fh_export->ex_flags & NFSEXP_FSID)
 645                 return FSIDSOURCE_FSID;
 646         if (fhp->fh_export->ex_uuid)
 647                 return FSIDSOURCE_UUID;
 648         return FSIDSOURCE_DEV;
 649 }